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Chemistry
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Electrocatalysis / PEM Electrolysis
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Numerical Values
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Unveiling Iridium Degradation Pathways during Intermittent Operation of a Proton Exchange Membrane Water Electrolyzer
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https://chemrxiv.org/engage/chemrxiv/article-details/68de8208dfd0d042d1a6002d
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October 6, 2025
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Researchers investigated iridium (Ir) loss and identified its deposition sites--namely, the anode water line (AWL), cathode water line (CWL), and cathode catalyst layer (CCL)--in a proton exchange membrane (PEM) electrolyzer subjected to three different accelerated stress tests (ASTs).
To achieve this, inductively coupled plasma mass spectrometry (ICP-MS) was employed to quantify dissolved Ir species and determine their distribution under varying operating conditions.
The experimental setup employed a custom-built electrolyzer cell with an active surface area of 5cm2. The membrane electrode assemblies (MEAs) were constructed using a PFSA (perfluorosulfonic acid) membrane, with a Pt black cathode (0.6 mg/cm2) and an Ir black anode (1.2mg/cm2). The porous transport layers (PTLs): a 280um carbon felt fiber paper was applied to the cathode side, while a 280um sintered titanium sheet with approximately 50% porosity was used for the anode. MEAs were tested at 60C and atmospheric pressure with 5ml/min of deionized water supplied to the anode side of the electrolyzer in a closed loop. Prior to any testing the electrolyzer was conditioned for 1 hour at 1A/cm2.
The two AST protocols simulated intermittent power supply conditions: a mitigated test (AST_1.3V) and an unmitigated test (AST_0V). In both cases, each AST cycle consisted of a 10-minute galvanostatic hold at 1 A cm⁻², followed by a 10-minute potentiostatic idle period. The idle potential was maintained at 1.3 V for AST_1.3V and 0 V for AST_0V. The ASTs consisted of 500 cycles in total. A chronopotentiometry (CP) method at 1 A cm⁻² for 20 minutes was used as reference.
Water samples were collected after the 500-cycle ASTs from both the anode and cathode lines. The quantification of dissolved Ir in these samples was performed ex-situ using an ICP-MS instrument (PerkinElmer, NexION 350). To assess Ir accumulation in the cathode catalyst layer, the cathodes were chemically digested in aqua regia and the resulting bulk solutions were analyzed by ICP-MS. For each experimental condition, at least two post-mortem digestion analyses were conducted to verify the reproducibility of the measured Ir content.
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-ICPMS of anode water line (AWL), cathode water line (CWL), and cathode catalyst layer (CCL) from electrolyzer after each AST protocol
-AWL dissolved Ir mass (µg) normalized to the geometric surface area of the MEA for AST_1.3V, AST_0V, and AST_CP
-CWL dissolved Ir mass (µg) normalized to the geometric surface area of the MEA for AST_1.3V, AST_0V, and AST_CP
-CCL dissolved Ir mass (µg) normalized to the geometric surface area of the MEA for AST_1.3V, AST_0V, and AST_CP
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Researchers utilized a custom-built proton exchange membrane (PEM) electrolyzer cell (5cm^2 active area) featuring a PFSA membrane, a Pt black cathode (0.6mg/cm2), and an Ir black anode (1.2mg/cm2) to study iridium loss and deposition under accelerated stress conditions. The cell, which used carbon felt paper (cathode) and sintered titanium (anode) as porous transport layers (PTLs), was conditioned and then subjected to three 500-cycle Accelerated Stress Tests (ASTs)—one mitigated (AST_1.3V) and one unmitigated (AST_0V)—that simulated intermittent power supply by cycling between a 1A/cm-2 load (10 min) and a 1.3V or 0V idle period (10 min). Additionally a chronopotentiometry (CP) method at 1 A cm⁻² for 20 minutes was used as reference. After 500 cycles, Inductively Coupled Plasma Mass Spectrometry (ICP-MS) was employed ex-situ to quantify the dissolved Ir in the water samples from the anode and cathode lines, and to determine the amount of Ir accumulated in the cathode catalyst layer (CCL) following chemical digestion. What is the expected difference of dissolved Ir (in ug/cm2) between the AST_1.3V AWL and AST_0V CWL?
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0.9-1.1 ug/cm2
(pm 10% fallback used)
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- An accelerated stress test (AST) is a procedure in which a full single cell or an individual component of an electrolyzer is subjected to elevated stress conditions--such as higher current densities, temperatures, or pressures--beyond normal operating levels, with the aim of accelerating and replicating the same degradation mechanisms that occur during regular operation.
- Dissolution and transport of catalysts within an electrolyzer are determined by the interplay between electro-migration and diffusion between the electrodes as intermittent current loading is applied.
- Studies have shown that in in AMS MEA systems less than 10% of the total dissolved Ir is found in the AWL and CWL under standard operating conditions
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[{"label":"RBK Item","value":"An accelerated stress test (AST) is a procedure in which a full single cell or an individual component of an electrolyzer is subjected to elevated stress conditions--such as higher current densities, temperatures, or pressures--beyond normal operating levels, with the aim of accelerating and replicating the same degradation mechanisms that occur during regular operation."},{"label":"Title","value":"Electrolyzer Performance Loss from Accelerated Stress Tests and Corresponding Changes to Catalyst Layers and Interfaces"},{"label":"URL","value":"https://iopscience.iop.org/article/10.1149/1945-7111/ac697e"},{"label":"Date","value":"May 16, 2022"},{"label":"Justification (\"Paywalled\", \"OA\", \"Other (justify)\")","value":"Paywalled"},{"label":"RBK Item","value":"Dissolution and transport of catalysts within an electrolyzer are determined by the interplay between electro-migration and diffusion between the electrodes as intermittent current loading is applied."},{"label":"Title","value":"Dynamic Neutron Imaging and Modeling of Cationic Impurities in Polymer Electrolyte Water Electrolyzer"},{"label":"URL","value":"https://iopscience.iop.org/article/10.1149/1945-7111/abc83b"},{"label":"Date","value":"November 17, 2020"},{"label":"Justification (\"Paywalled\", \"OA\", \"Other (justify)\")","value":"OA"},{"label":"RBK Item","value":"Studies have shown that in in AMS MEA systems less than 10% of the total dissolved Ir is found in the AWL and CWL under standard operating conditions"},{"label":"Title","value":"Microscopic insights on the degradation of a PEM water electrolyzer with ultra-low catalyst loading"},{"label":"URL","value":"https://www.sciencedirect.com/science/article/pii/S0926337319309415"},{"label":"Date","value":"September 16, 2019"},{"label":"Justification (\"Paywalled\", \"OA\", \"Other (justify)\")","value":"Paywalled"}]
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Chemistry
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Inorganic Chemistry
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MCQ
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Size-Dependent Optical Gaps in Metal-Organic Framework Nanoparticles
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https://chemrxiv.org/engage/chemrxiv/article-details/68f7ca1f3e6156d3be2de9d3
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Aug 19, 2025
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Researchers synthesized nanoparticles of M(TA)₂ (M = Mn, Fe, Cd, Cr, Co, Zn) using metal precursors, triazolate ligands, and modulator-controlled or stoichiometry-controlled routes that produced samples spanning different crystalline domain sizes. For each metal variant, several particle sizes were generated by adjusting metal:ligand stoichiometry, modulator identity, or precursor concentration, and crystallite sizes were confirmed by Scherrer analysis. High-resolution powder X-ray diffraction (PXRD) patterns were collected for each M(TA)₂ sample across its particle-size series. Crystalline domain size (nm) and unit cell parameters were determined from Pawley refinements of the PXRD data. To quantify changes in lattice structure as particle size decreased, unit cell volume, strain (ε, %), and microstrain (e, %) were extracted using double-Voigt integral breadth methods implemented in TOPAS Academic V6 with corrections for instrument-dependent line broadening.
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- Crystalline domain size (nm) for each M(TA)₂ sample, determined from PXRD line broadening under high-resolution powder X-ray diffraction (HRPXRD) conditions (Cu Kα radiation).
- Unit cell parameters and unit cell volume (ų) for each M(TA)₂ sample, obtained from Pawley refinement of high-resolution PXRD patterns.
- Strain (ε, %) and microstrain (e, %) for each M(TA)₂ sample, extracted using double-Voigt integral breadth methods.
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Nanoparticles of M(TA)₂ (M = Mn, Fe, Cd, Cr, Co, Zn) were synthesized in different size regimes, and their unit cell parameters were extracted from high-resolution PXRD followed by Pawley refinement. The analysis reports whether decreasing crystalline domain size is associated with a contraction or an expansion of the unit cell volume for each metal variant.
Which of the following outcomes is most likely?
A. Mn(TA)₂ nanoparticles show unit cell contraction with decreasing size, while Fe(TA)₂ nanoparticles show unit cell expansion.
B. Mn(TA)₂ nanoparticles show unit cell expansion with decreasing size, while Fe(TA)₂ nanoparticles show unit cell contraction.
C. Both Mn(TA)₂ and Fe(TA)₂ nanoparticles show unit cell expansion with decreasing size.
D. Both Mn(TA)₂ and Fe(TA)₂ nanoparticles show unit cell contraction with decreasing size.
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A. Mn(TA)₂ nanoparticles show unit cell contraction with decreasing size, while Fe(TA)₂ nanoparticles show unit cell expansion.
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- Colloidal nanocrystals of the metal-organic framework (MOF) Fe(1,2,3-triazolate)2 (Fe(TA)2) exhibit size-dependent optical behavior that eludes explanation by conventional models such as quantum confinement, or by unintentional effects such as Fe oxidation or change of spin state.
- Emerging evidence suggests that metal-linker bonding in MOFs becomes more labile and tolerant to structural distortion as particle sizes decrease. We have argued previously24 that this behavior may relate, at a fundamental level, to the observation that lattice constants generally increase while phase change critical
temperatures decrease as semiconductor particle diameters diminish in size.
|
[{"label":"RBK Item","value":"Colloidal nanocrystals of the metal-organic framework (MOF) Fe(1,2,3-triazolate)2 (Fe(TA)2) exhibit size-dependent optical behavior that eludes explanation by conventional models such as quantum confinement, or by unintentional effects such as Fe oxidation or change of spin state."},{"label":"Title","value":"Size-Dependent Properties of Solution-Processable Conductive MOF Nanocrystals"},{"label":"URL","value":"https://pubs.acs.org/doi/abs/10.1021/jacs.1c10800"},{"label":"Date","value":"March 28, 2022"},{"label":"Justification (\"Paywalled\", \"OA\", \"Other (justify)\")","value":"Paywalled"},{"label":"RBK Item","value":"Emerging evidence suggests that metal-linker bonding in MOFs becomes more labile and tolerant to structural distortion as particle sizes decrease. We have argued previously24 that this behavior may relate, at a fundamental level, to the observation that lattice constants generally increase while phase change critical\ntemperatures decrease as semiconductor particle diameters diminish in size."},{"label":"Title","value":"‘Madelung model’ prediction for dependence of lattice parameter on nanocrystal size"},{"label":"URL","value":"https://www.sciencedirect.com/science/article/abs/pii/S0038109802002661"},{"label":"Date","value":"August 27, 2002"},{"label":"Justification (\"Paywalled\", \"OA\", \"Other (justify)\")","value":"Paywalled"}]
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Chemistry
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Chemistry, Spectroscopy, Chemometrics and Statistics
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MCQ
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Semi-Targeted Nuclear Magnetic Resonance Metabolomics via Parahydrogen-Induced Hyperpolarization for Enhanced Sensitivity to Metabolic Composition
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https://pmc.ncbi.nlm.nih.gov/articles/PMC12426882/pdf/ja5c11226.pdf
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August 26, 2025
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Researchers investigated whether non-hydrogenative para-hydrogen-induced polarization (nhPHIP) NMR could improve metabolite detection in urine compared to conventional ¹H NMR. Urine samples from ten pyridoxine-dependent epilepsy (PDE) patients and nineteen healthy controls were analyzed to assess group discrimination based on metabolic composition. For nhPHIP measurements, samples were prepared with an Ir-IMes catalyst (0.43-0.85 mM concentration), pyridine as cosubstrate (7.3-15 mM), and either piperidine (10.2mM, pH=11.1) or triethylamine buffer (20 mM). Para-enriched hydrogen gas (51%) was bubbled through the solution at 5 bar pressure. Spectra were acquired at 10 °C using a 600 MHz NMR spectrometer. Two nhPHIP datasets were collected, corresponding to the recorded signals: one-dimensional (1D) hydride spectra and two-dimensional (2D) zero-quantum (ZQ) spectra. The 1D spectra required approximately 2 min per sample, while 2D ZQ spectra required about 1 h. For comparison, conventional 1D ¹H NMR spectra were acquired on both groups under same conditions (H₂O/D₂O 90:10 v/v, pH 2.5, 298 K, 600 MHz-H). Principal Component Analysis (PCA) was performed on all datasets to evaluate whether each method could separate PDE and control samples.
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- Signals from 1D nhPHIP ¹H NMR, 2D nhPHIP zero-quantum (ZQ), and conventional 1D ¹H NMR spectra for urine samples from pyridoxine-dependent epilepsy (PDE) patients and healthy controls.
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Urine samples were studied with NMR for two groups, 10 samples for pyridoxine-dependent epilepsy (PDE) patients group and a control group. Different NMR methodlogies were used, 1D nhPHIP NMR spectroscopy, 2D nhPHIP zero quantum (ZQ) NMR spectroscopy and conventional 1D ¹H NMR spectroscopy. After acquiring the spectra, Principal Component Analysis (PCA) was performed on all three datasets to determine if the methods could discriminate between PDE patients and healthy controls based on their urinary metabolite profiles.
Which of the following outcomes is most likely regarding the separation between PDE and control groups?:
A) The 2D nhPHIP ZQ method partially separated the two groups, while the 1D nhPHIP and conventional ¹H NMR methods showed no clear discrimination.
B) Both the 1D nhPHIP and 2D nhPHIP ZQ methods achieved clear and statistically significant separation between the PDE and control groups, whereas the conventional ¹H NMR data showed no separation.
C) Only the 2D nhPHIP ZQ method achieved separation between groups, while both the 1D nhPHIP and conventional ¹H NMR spectra produced overlapping clusters.
D) All three methods successfully separated PDE from control samples, although the nhPHIP approaches showed slightly better resolution.
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B) Both the 1D nhPHIP and 2D nhPHIP ZQ methods achieved clear and statistically significant separation between the PDE and control groups, whereas the conventional ¹H NMR data showed no separation.
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- Pyridoxine-Dependent Epilepsy (PDE): an inherited metabolic disorder, derives from mutations in the gene encoding α-aminoadipic semialdehyde (α-AASA) dehydrogenase, also known as antiquitin, and currently diagnosed by the presence of dilute unique biomarkers.
- NMR: has gained an important role in metabolomics, for a large part due to its wide analyte scope, the minimal sample preparation, its reproducibility, and unique quantitative character.
- Nonhydrogenative parahydrogen-induced hyperpolarization (nhPHIP): The selective character of nhPHIP-NMR makes it suitable for semi-targeted metabolomics to access low concentrations of the aforementioned classes of metabolites.
-1D nhPHIP NMR: afford sensitivity and wide applicability, thanks to the ubiquitous presence of proton spins in bioorganic molecules. However, analytes at low- or submicromolar concentrations remain generally below the NMR detection limit.
- 2D nhPHIP zero quantum (ZQ) NMR: When dealing with complex mixtures, such as biological samples, the overlap of the hydride resonances can be resolved by 2D zero quantum (ZQ) spectroscopy: hydride signals corresponding to different α-amino acids can be spread in the indirect dimension.
|
[{"label":"RBK Item","value":"- Pyridoxine-Dependent Epilepsy (PDE): an inherited metabolic disorder, derives from mutations in the gene encoding α-aminoadipic semialdehyde (α-AASA) dehydrogenase, also known as antiquitin, and currently diagnosed by the presence of dilute unique biomarkers."},{"label":"Title","value":"Mutations in antiquitin in individuals with pyridoxine-dependent seizures"},{"label":"URL","value":"https://www.nature.com/articles/nm1366"},{"label":"Date","value":"February 19, 2006"},{"label":"Justification (\"Paywalled\", \"OA\", \"Other (justify)\")","value":"Paywalled"},{"label":"RBK Item","value":"NMR: has gained an important role in metabolomics, for a large part due to its wide analyte scope, the minimal sample preparation, its reproducibility, and unique quantitative character."},{"label":"Title","value":"High-Throughput Metabolomics by 1D NMR"},{"label":"URL","value":"https://onlinelibrary.wiley.com/doi/full/10.1002/anie.201804736"},{"label":"Date","value":"July 12, 2018"},{"label":"Justification (\"Paywalled\", \"OA\", \"Other (justify)\")","value":"OA"},{"label":"RBK Item","value":"Nonhydrogenative parahydrogen-induced hyperpolarization (nhPHIP): The selective character of nhPHIP-NMR makes it suitable for semi-targeted metabolomics to access low concentrations of the aforementioned classes of metabolites."},{"label":"Title","value":"Analysis of Complex Mixtures by Chemosensing NMR Using para-Hydrogen-Induced Hyperpolarization"},{"label":"URL","value":"https://pubs.acs.org/doi/full/10.1021/acs.accounts.1c00796"},{"label":"Date","value":"June 16, 2022"},{"label":"Justification (\"Paywalled\", \"OA\", \"Other (justify)\")","value":"OA"}]
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Chemistry
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Materials Science, Electrochemistry
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MCQ
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Enhanced voltage and capacitance in flexible supercapacitors using electrospun nanofiber electrolytes and CuNi2O3@N‑Doped omnichannel carbon electrodes
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https://nanoconvergencejournal.springeropen.com/articles/10.1186/s40580-025-00485-2
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April 29, 2025
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Researchers prepared CuNi2O3@N-OCCF electrodes and investigated their electrochemical properties. The fabrication of CuNi2O3@N-OCCFs was a two-step process starting with electrospinning, which required preparing two precursor solutions. Solution A contained 8 wt% PAN and 12 wt% PMMA (1:1.5 w/w) in DMF. Solution B consisted of 1.5 wt% SDS (sodium dodecyl sulfate), 2.0 mmol Cu(CH3CO2)2, and 4.0 mmol Ni(CH3CO2)2 in DMF. After 6 hours of individual agitation, Solution B was added to Solution A, and the mixture was stirred for 6 more hours to create the working liquid. This liquid was electrospun at 15 kV onto aluminum foil, maintaining an 18 cm distance, and the collected nanofibers were vacuum-dried at 70 °C for 12 hours. The final material, CuNi2O3@N-OCCFs-1.5, was achieved by subjecting the film to stabilization in air at 270 °C for 2 hours, followed by carbonization at 600-900 °C for 2 hours in a high-purity N2 environment. The SDS additive facilitated the migration of the CuNi2O3 particles to the nanofiber surface during annealing. Other compositions of CuNi2O3@N-OCCFs were prepared by adjusting the PAN-to-PMMA ratio, while the metal-free N-OCCFs (0.5 to 2) were prepared using the same electrospinning and 900 °C carbonization procedure but without the addition of SDS, copper, or nickel salts in the precursor solution.
The electrode preparation began with purifying the carbon cloth (CC), which was sequentially washed with 3 M HCl, acetone, ethanol, and deionized water for 10 minutes, and then dried at 60 °C for 6 hours. The CC was cut into 2×1.5 cm pieces and further cleaned with acetone. The final electrode composite was fabricated by blending the active material (CuNi2O3@N-OCCFs-1.5 or N-OCCFs-1.5), Super B, and polyvinylidene difluoride in an 8:1:1 weight ratio using a mortar and pestle, and then adding NMP solvent to form a slurry. This slurry was coated evenly onto the CC with a loading mass of about 2.0 mg/cm2 and allowed to dry for 5 hours at room temperature. The resulting CuNi2O3@N-OCCFs-1.5/CC and N-OCCFs-1.5/CC served as the working electrodes for electrochemical measurements. The full setup for a three-electrode system used an Ag/AgCl (saturated KCl) reference electrode and a platinum wire counter electrode, with 2.0 M KCl, NaCl, or LiCl as the aqueous electrolyte. Electrochemical Impedance Spectroscopy (EIS) was measured using a multichannel potentiostat in the frequency range of 0.01 Hz to 100 kHz.
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- Cyclic voltammetry (CV) of CuNi2O3@N-OCCFs-1.5 symmetric supercapacitors in 2.0 M LiCl, NaCl, and KCl at scan rates between 5 and 100 mV/s over a potential window of 0–0.6 V.
- Galvanostatic charge–discharge (GCD) curves of CuNi2O3@N-OCCFs-1.5 symmetric supercapacitors in 2.0 M LiCl, NaCl, and KCl at current densities between 1 and 8 A/g over a potential window of 0–0.45 V.
- Specific capacitance of CuNi2O3@N-OCCFs-1.5 symmetric supercapacitors in 2.0 M LiCl, NaCl, and KCl as a function of current density from 1 to 8 A/g, extracted from the GCD profiles.
|
Researchers fabricated CuNi2O3@N-OCCF active materials using a two-step process involving the electrospinning of two precursor solutions (one containing PAN/PMMA and the other metal salts/SDS) followed by high-temperature stabilization and carbonization in N2. The final working electrodes were prepared by mixing the active material with Super B and PVDF (in an 8:1:1 ratio) to form a slurry, which was then coated onto a cleaned carbon cloth (CC) substrate. These electrodes were subjected to electrochemical measurements (such as EIS) in a three-electrode system utilizing an aqueous 2.0 M electrolyte and Ag/AgCl and Pt wire as reference and counter electrodes, respectively. Cyclic voltammetry between 0 and 0.6V at scan rates between 5-100mV/s and galvanostatic charge-discharge curves were collected between 1A/g and 8A/g in 2M LiCl, NaCl, and KCl electrolytes. The specific capacitance was calculated in the three electrolytes as a function of current density between 1A/g and 8A/g. In which of the 3 electrolytes is the specific capacitance of the electrodes expected to be the least at 2A/g current density?
A. LiCl
B. NaCl
C. KCl
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C. KCl
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-The selection and design of electrolyte plays a critical role in supercapacitor performance by shuttling ions between electrodes over wide potential windows
- Li+ ions can intercalate and deintercalated within the electrode material during charge and discharge cycles can be attributed to more efficient ion storage and utilization
|
[{"label":"RBK Item","value":"Li+ ions can intercalate and deintercalated within the electrode material during charge and discharge cycles can be attributed to more efficient ion storage and utilization"},{"label":"Title","value":"Low-grade heat recycling of vertical thermoelectric cells based on thermal-induced electric double layer"},{"label":"URL","value":"https://www.sciencedirect.com/science/article/pii/S2468217924000339?via%3Dihub"},{"label":"Date","value":"March 4, 2024"},{"label":"Justification (\"Paywalled\", \"OA\", \"Other (justify)\")","value":"OA"}]
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Chemistry
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Electrochemistry
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MCQ
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Selective CO2-to-Formate Electroreduction Using Cu3Sn Gas Diffusion Electrodes Synthesized via a Scalable Electrochemical Route
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https://chemrxiv.org/engage/chemrxiv/article-details/68e619b5dfd0d042d16d2281
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October 10, 2025
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Researchers examined electrochemical CO2 reduction using CuSn gas diffusion electrodes (GDEs) in a flow cell electrolyser. The preparation of CuSn GDE electrode was as follows. Commercial Cu2O particles were brush coated onto the surface of a 1cm×1cm commercial carbon gas diffusion layer, using ink consisting of 15 mg of Cu2O, 200 μL of isopropanol and 66 μL of a 5 wt% Nafion suspension (all sonicated for 20 minutes). Each applied coating layer was dried for 1-3 minutes at at 40-50C until 4-5mg/cm2 mass loading was achieved. In the second step Sn is deposited onto Cu2O-based gas diffusion electrodes using an in-situ electrochemical simultaneous deposition (ESD) method. The setup involved Cu2O GDE as the cathode and a tin foil as the anode, both immersed in an electrolyte containing 0.1 M SnCl4·5H2O and 0.05 M citric acid, running against a 2ohm potential. The deposition times of Sn on Cu2O GDE were 15, 28, and 35 minutes.
Electrochemical measurements were conducted using an Autolab potentiostat/galvanostat (Metrohm Autolab PGSTAT302N) in a lab-customized 3D-printed electrolyser flow cell to investigate electrocatalytic CO2 reduction (ECR) catalysts. The setup utilized Ag/AgCl as the reference electrode, which was converted to the Reversible Hydrogen Electrode (RHE) potential using the equation E_RHE = E_Ag/AgCl + 0.1976 + 0.0591 x pH, and a Pt mesh as the counter electrode. The catalysts were deposited on a carbon paper GDL substrate. CO2 gas was continuously supplied to the gas chamber at a constant flow rate of 22 mL min-1, diffusing across the GDL to the catalyst layer. A Fumasem FBM bipolar membrane separated the cathodic and anodic compartments, with Platinum mesh serving as the anode. To investigate ECR behavior of CuSn electrodes, chronoamperometry (CA) tests were performed for 1 hour at various potentials: -0.5 V, -0.65 V, -0.75 V, -0.85 V, and -1.00 V vs. RHE. The Faradaic efficiency (FE) was estimated from the CA measurements by accounting for the input charge, reaction duration, and the quantified molar masses of the gaseous and liquid products.
After electrolysis, 1 mL gas samples were taken via a septum port using a gas-tight syringe and injected into a Shimadzu 2014 Gas Chromatograph (GC) for the quantification of CO, H2, and hydrocarbons. Liquid products were analyzed using Thermo-Fisher Dionex ICS-1600 Ion Chromatography. The GC was equipped with a Thermal Conductivity Detector (TCD) to detect H2, and a Flame Ionization Detector (FID) with a methanizer to detect CO and other carbon-based gaseous products, using Argon as the carrier gas.
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-Normalized faradaic efficiencies for hydrogen, formic acid, carbon monoxide, methane, and ethylene for Cu2O, CuSn15min, CuSn28min, CuSn35min, and Sn foil, at -0.75 V vs. RHE
-Faradaic efficiency of formic acid and hydrogen production for Cu2O, Sn foil, CuSn15, CuSn28, and CuSn35 (Cu3Sn) during ECR between -0.5 and -1.00 V vs. RHE
-Partial current density of formic acid and hydrogen production for Cu2O, Sn foil, CuSn15, CuSn28, and CuSn35 (Cu3Sn) during ECR at -0.5 and -1.00 V vs. RHE
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Researchers prepared CuSn gas diffusion electrodes (GDEs) for electrochemical CO2 reduction (ECR) in a flow cell electrolyser. The preparation involved brush-coating Cu2O particles in a Nafion ink onto a carbon GDL, achieving a mass loading of 4-5 mg/cm2. Sn was then deposited onto the Cu2O GDE using an in-situ electrochemical deposition method at a 2 ohm potential against a Tin foil anode, with deposition times of 15, 28, and 35 minutes. ECR testing was conducted in a customized 3D-printed flow cell using a potentiostat/galvanostat, with the CuSn catalyst tested against a Pt mesh counter electrode and an Ag/AgCl reference electrode (potential converted to RHE). The cell utilized a bipolar membrane, a Pt anode, and a constant flow of CO2 gas at 22 mL min-1. ECR performance was studied via 1 hour chronoamperometry (CA) tests across potentials from -0.5 V to -1.00 V vs. RHE. Product analysis after electrolysis involved quantifying gaseous products (CO, H2, and hydrocarbons) using gas chromatography (GC with TCD and FID detectors) and liquid products using ion chromatography. How do the formic acid faradaic efficiencies of Cu2O, Sn foil, CuSn15, CuSn28, and CuSn35 compare at ~-0.9V vs. RHE?
A. Cu2O<Sn foil<CuSn15<CuSn28<CuSn35
B. Cu2O<Sn foil<CuSn28<CuSn15<CuSn35
C. Cu2O<CuSn28<Sn foil<CuSn15<CuSn35
D. Sn foil<CuSn28<Cu2O<CuSn15<CuSn35
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C. Cu2O<CuSn28<Sn foil<CuSn15<CuSn35
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-Sn-based GDE have excellent formate selectivity at relatively low overpotentials
-Bimetallic Cu-Sn systems combine Cu's ability to activate CO2 with Sn's selectivity for the *OCHO intermediate pathway
|
[{"label":"RBK Item","value":"-Sn-based GDE have excellent formate selectivity at relatively low overpotentials"},{"label":"Title","value":"CO2 to Formic Acid Using Cu–Sn on Laser-Induced Graphene"},{"label":"URL","value":"https://pubs.acs.org/doi/10.1021/acsami.0c08964"},{"label":"Date","value":"August 24, 2020"},{"label":"Justification (\"Paywalled\", \"OA\", \"Other (justify)\")","value":"Paywalled"},{"label":"RBK Item","value":"-Bimetallic Cu-Sn systems combine Cu's ability to activate CO2 with Sn's selectivity for the *OCHO intermediate pathway"},{"label":"Title","value":"Heterostructured intermetallic CuSn catalysts: high performance towards the electrochemical reduction of CO2 to formate"},{"label":"URL","value":"https://pubs.rsc.org/en/content/articlelanding/2019/ta/c9ta11140a"},{"label":"Date","value":"November 22, 2019"},{"label":"Justification (\"Paywalled\", \"OA\", \"Other (justify)\")","value":"Paywalled"}]
|
Chemistry
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Chemistry, Catalysis
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MCQ
|
CO2 methanation with MOF-derived hierarchically porous spherical carbon nanocomposite incorporating cobalt nanoparticles
|
https://chemrxiv.org/engage/chemrxiv/article-details/68ee235abc2ac3a0e0e2a488
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September 8, 2025
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Investigators compared the CO₂ conversion performance and CH4 selectivity of CoNDC catalysts prepared from a metal–organic framework (MOF) precursor. The CoNDC material was synthesized by reacting Co(II)(acac)₂ with 2,6-naphthalene dicarboxylic acid in a microwave reactor at 160 °C for 40 minutes, followed by carbonization at 600 °C or 700 °C for 2 h under argon with a heating rate of 5 °C min⁻¹, yielding CoNDC-600 and CoNDC-700. Catalytic tests for CO₂ methanation were conducted in a continuous-flow fixed-bed reactor at atmospheric pressure using 100 mg of catalyst. For each catalyst, two conditions were evaluated: one using the as-prepared material and another using samples reduced in situ in 50 % (v/v) H₂ diluted in Ar at 400 °C for 1 h (20 mL min⁻¹). The feed consisted of 10 % CO₂ and 40 % H₂ (balance Ar) at a total flow rate of 20 mL min⁻¹, with temperature steps from 200 °C to 400 °C in 50 °C increments. The outlet gases were analyzed by gas chromatography (SCION 456-GC) using TCD and FID detectors to quantify reaction products.
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- CO₂ conversion (%) calculated from outlet gas composition using a gas chromatograph (SCION 456-GC), under total flow rate of 20 mL/min, (10 % CO₂ + 40 % H₂ in Ar) and temperatures between 200–400 °C.
-CH4 selectivity (%) calculated from outlet gas composition using a gas chromatograph (SCION 456-GC), under total flow rate of 20 mL/min, (10 % CO₂ + 40 % H₂ in Ar) and temperatures between 200–400 °C.
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Metal–organic framework (MOF)–derived CoNDC catalysts were prepared by carbonizing a Co-based MOF precursor at 600 °C (CoNDC-600) and 700 °C (CoNDC-700) for 2 h under an argon atmosphere with a heating rate of 5 °C min⁻¹. Some samples of each catalyst were reduced in situ in 50 % (v/v) H₂ diluted in Ar at 400 °C for 1 h before being tested for CO₂ methanation. The reaction was carried out in a continuous-flow fixed-bed reactor at atmospheric pressure, using a feed mixture of 10 % CO₂ and 40 % H₂ (balance Ar) at a total flow rate of 20 mL min⁻¹, with temperature steps from 200 °C to 400 °C in 50 °C increments. Which of the following outcomes is most likely?
A. Reduced CoNDC-700 shows the highest CO₂ conversion and CH₄ selectivity in the 250–350 °C range.
B. Reduced CoNDC-600 shows the highest CO₂ conversion and CH₄ selectivity in the 250–350 °C range.
C. Unreduced CoNDC-700 shows the highest CO₂ conversion and CH₄ selectivity in the 250–350 °C range.
D. Reduced CoNDC-600 shows the highest CO₂ conversion, whereas all catalysts exhibit similar CH₄ selectivity in the 250–350 °C range.
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D. Reduced CoNDC-600 shows the highest CO₂ conversion, whereas all catalysts exhibit similar CH₄ selectivity in the 250–350 °C range.
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- Metal–organic framework (MOF): a porous crystalline material constructed from metal ions or clusters coordinated to organic ligands, serving as a precursor that, upon carbonization, yields the CoNDC catalysts.
- CoNDC material: is a hierarchically porous spherical carbon nanocomposite incorporating cobalt nanoparticles, obtained by carbonization of a cobalt-based metal–organic framework precursor.
- CoNDC-600: Obtained catalysis carbonized material corresponding to the carbonization temperature of 600 °C.
- CoNDC-700: Obtained catalysis carbonized material corresponding to the carbonization temperature of 700 °C.
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[{"label":"RBK Item","value":"Cobalt oxide (CoO) and metallic cobalt (Co) nanoparticles exhibit distinct catalytic behaviors, with the former being active in the hydrogenation of CO2 to CO or hydrocarbons, and the latter in the hydrogenation to methane."},{"label":"Title","value":"Uncovering the reaction mechanism behind CoO as active phase for CO2 hydrogenation"},{"label":"URL","value":"https://doi.org/10.1038/s41467-022-27981-x"},{"label":"Date","value":"January 14, 2022"},{"label":"Justification (\"Paywalled\", \"OA\", \"Other (justify)\")","value":"OA"},{"label":"RBK Item","value":"Metal-organic framework (MOF)-derived cobalt carbon composite catalysts have emerged as promising materials for heterogeneous thermocatalysis."},{"label":"Title","value":"Metal‐Organic Framework–Specific Catalysis"},{"label":"URL","value":"https://doi.org/10.1002/cctc.202402102"},{"label":"Date","value":"February 19, 2025"},{"label":"Justification (\"Paywalled\", \"OA\", \"Other (justify)\")","value":"OA"},{"label":"RBK Item","value":"Co-based catalysts derived from various MOFs have been utilized to create Co nanoparticles embedded in a nitrogen-doped carbon framework. This configuration promotes CO2 adsorption but also enhances the overall methanation catalytic activity."},{"label":"Title","value":"Metal–Carbon Composite Catalysts by One-Step Conversion of MOF Crystals in a Sealed-Tube Reactor"},{"label":"URL","value":"https://doi.org/10.1021/acsaem.0c02208"},{"label":"Date","value":"November 25, 2020"},{"label":"Justification (\"Paywalled\", \"OA\", \"Other (justify)\")","value":"No OA version available; paywalled source is the canonical reference for this RBK item."}]
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Chemistry
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Nanotechnology / Catalysis
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Free-Format Question
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Tuning Nanostructure of Flame-made Palladium deposited on Cerium Oxide: Unveiling Pd Loading–Activity Relationships in Suzuki–Miyaura Cross-Coupling
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https://chemrxiv.org/engage/chemrxiv/article-details/68d4f0953e708a7649229138
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September 24, 2025
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Researchers evaluated the catalytic reaction performance of the Suzuki-Miyaura cross-coupling reaction by synthesizing a palladium-deposited cerium oxide (Pd/CeO2) catalyst with different Pd proportions (0.1, 5, 10, 20 and 50%wt) and then evaluating the conversion rate of 4-iodobenzonitrile to 4-phenylbenzonitrile when adding the catalyst. They loaded a round-bottom flask equipped with a magnetic stir bar with potassium hydroxide (28.1 mg), 4-iodobenzonitrile (57.3 mg), phenylboronic acid (45.7 mg), methanol (3.75 mL) and tetrahydrofuran (3.75 mL), tetradecane (49.6 mg) as an internal standard, and palladium-deposited cerium oxide (Pd 5 mol, % relative to 4-iodobenzonitrile). The reaction mixture was stirred at room temperature under open-air atmosphere for 6 hours. The yield of the formed product (4-phenylbenzonitrile) was obtained with gas chromatography (SHIMADZU GC-2014 with column, Restek Rtx-200; 0.25 mm x 30 m). The target product was isolated and identified by NMR using a JEOL JNM-ECZ400 spectrometer (1H: 400 MHz, referenced to tetramethylsilane at 0.0 ppm; 13C: 100 MHz, referenced to the central peak of CDCl3 at 77.0 ppm).
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- Conversion yields from 4-iodobenzonitrile and phenylboronic acid to 4-phenylbenzonitrile, in percentage.
- Turnover number of Pd/CeO2 catalysts.
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Researchers evaluated the catalytic reaction performance of the Suzuki-Miyaura cross-coupling reaction by synthesizing a palladium-deposited cerium oxide (Pd/CeO2) catalyst with different Pd proportions (0.1, 5, 10, 20 and 50%wt) and then evaluating the conversion rate of 4-iodobenzonitrile to 4-phenylbenzonitrile when adding the catalyst. They loaded a round-bottom flask equipped with a magnetic stir bar with potassium hydroxide (28.1 mg), 4-iodobenzonitrile (57.3 mg), phenylboronic acid (45.7 mg), methanol (3.75 mL) and tetrahydrofuran (3.75 mL), tetradecane (49.6 mg) as an internal standard, and palladium-deposited cerium oxide (Pd 5 mol, % relative to 4-iodobenzonitrile). The reaction mixture was stirred at room temperature under open-air atmosphere for 6 hours. The yield of the formed product (4-phenylbenzonitrile) was obtained with gas chromatography. The target product was isolated and identified by NMR using a JEOL JNM-ECZ400 spectrometer. What proportion of Pd in the Pd/CeO2 catalyst will result in a larger turnover number (TONs)?
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The 5Pd/CeO2 system, since proportions greater than 10 % of Pd in the Pd/CeO2 catalyst have a lower surface enrichment of Pd in the CeO2 due to the lack of free spaces for anchoring, and this reduces its turnover number (TONs).
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- The Suzuki–Miyaura cross-coupling (SMC) reaction is a method for constructing C–C bonds.
- Cerium oxide (CeO2) is used as a support for Pd catalysts since the facile Ce4+/Ce3+ redox cycling and abundant surface oxygen vacancies of CeO2 enable it to stabilize dispersed Pd species and to participate actively in catalytic processes
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[{"label":"RBK Item","value":"The Suzuki–Miyaura cross-coupling (SMC) reaction is a method for constructing C–C bonds."},{"label":"Title","value":"State-of-the-Art in Metal-Catalyzed Cross-Coupling Reactions of Organoboron Compounds with Organic Electrophiles"},{"label":"URL","value":"https://doi.org/10.1002/9783527655588.ch2"},{"label":"Date","value":"November 30, 2013"},{"label":"Justification (\"Paywalled\", \"OA\", \"Other (justify)\")","value":"Paywalled"},{"label":"RBK Item","value":"Cerium oxide (CeO2) is used as a support for Pd catalysts since the facile Ce4+/Ce3+ redox cycling and abundant surface oxygen vacancies of CeO2 enable it to stabilize dispersed Pd species and to participate actively in catalytic processes\n"},{"label":"Title","value":"Effect of Support on CO Oxidation Performance over the Pd/CeO2 and Pd/CeO2–ZrO2 Catalyst"},{"label":"URL","value":"https://doi.org/10.1021/acs.iecr.9b05351"},{"label":"Date","value":"January 7, 2020"},{"label":"Justification (\"Paywalled\", \"OA\", \"Other (justify)\")","value":"Paywalled"},{"label":"RBK Item","value":"Cerium oxide (CeO2) is used as a support for Pd catalysts since the facile Ce4+/Ce3+ redox cycling and abundant surface oxygen vacancies of CeO2 enable it to stabilize dispersed Pd species and to participate actively in catalytic processes\n"},{"label":"Title","value":"Metallic palladium, PdO, and palladium supported on metal oxides for the Suzuki–Miyaura cross-coupling reaction: a unified view of the process of formation of the catalytically active species in solution"},{"label":"URL","value":"https://doi.org/10.1039/C7CY01201B"},{"label":"Date","value":"August 01, 2017"},{"label":"Justification (\"Paywalled\", \"OA\", \"Other (justify)\")","value":"Paywalled"}]
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Chemistry
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Organic chemistry
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Free-Format Question
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Transient π-Coordination Enables Nucleophilic Borylation of Simple Arenes
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https://chemrxiv.org/engage/chemrxiv/article-details/68f5874d3e6156d3bee5586a
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April 21, 2025
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In an argon-filled glove box, a J-Young-type Schlenk tube (φ16 mm) equipped with a glass-covered stir bar was charged with [Cr(arene)(CO)₃] (0.20 mmol), B₂(pin)₂ (101.6 mg, 0.40 mmol, 2 equiv), and one of several additives: K₂CO₃ (27.6 mg, 0.20 mmol), Na₂CO₃, Li₂CO₃, KOMe, KOtBu, KF, or CsF with or without [Cr(acac)₃] (3.5 mg, 0.01 mmol, 0.05 equiv) as a catalytic additive. The mixture was prepared under nitrogen, THF (1.0 mL) was added, and the system was degassed by three freeze pump thaw cycles. The reaction was stirred at 100 °C for 24 h (ca. 500 rpm) in a preheated metal block and then cooled to room temperature. Afterward, AcOH (0.8 mL) and MnO₂ (54–58 mg, ca. 0.6 mmol, 3 equiv) were successively added, and the mixture was stirred for 3 h at room temperature. The reaction was diluted with EtOAc (≈5 mL), and tridecane (18–20 mg, ca. 0.1 mmol) was introduced as an internal standard for GC analysis. An aliquot was filtered through Florisil with EtOAc and analyzed by GC and GC/MS to estimate the yield of the borylated product (2a).
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- Yield of the borylated product (%) by GC (tridecane IS) for additives K₂CO₃/Na₂CO₃/Li₂CO₃/KOMe/KOtBu/KF/CsF with/without [Cr(acac)₃] (24 h, 100 °C, THF).
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Researchers performed the borylation of [Cr(arene)(CO)₃](0.20 mmol) with B₂(pin)₂ (101.6 mg, 0.40 mmol, 2 equiv) in THF (1.0 mL) at 100 °C for 24 h in a J-Young-type Schlenk tube under nitrogen, using various additives including K₂CO₃ (27.6 mg, 0.20 mmol), Na₂CO₃, Li₂CO₃, KOMe, KOtBu, KF, and CsF. The yield of the borylated product 2a was determined by GC analysis using tridecane as an internal standard. Under these conditions, which additive without catalytic assistance afforded the highest yield of the borylated product, and what qualitative effect was observed when [Cr(acac)₃] (3.5 mg, 0.01 mmol, 0.05 equiv) was added together with this most efficient additive?
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K₂CO₃ gave the highest yield among the additives tested, and the presence of [Cr(acac)₃] led to a further increase in yield.
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- [Cr(arene)(CO)₃]: transient π-coordination to chromium activates 1 equiv of a simple arene towards nucleophilic borylation.
- Arene: functionalization of the C–H bond in an arene enables rapid construction of molecular complexity.
- B₂(pin)₂: 1 equiv of a simple arene can be borylated with B₂(pin)₂ in the presence of a base such as K₂CO₃
- Additives: additive such as K₂CO₃, enable the reaction proceeds well without the need of the catalyst.
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[{"label":"RBK Item","value":"Arene: functionalization of the C–H bond in an arene enables rapid construction of molecular complexity. "},{"label":"Title","value":"Handbook of C–H Transformations: Applications in Organic Synthesis"},{"label":"URL","value":"https://onlinelibrary.wiley.com/doi/book/10.1002/9783527619450"},{"label":"Date","value":"August 24, 2005"},{"label":"Justification (\"Paywalled\", \"OA\", \"Other (justify)\")","value":"Paywalled"}]
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Chemistry
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Organic Chemistry / Catalysis
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Numerical Values
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Enantioselective Cobalt(III)-Catalyzed [4 + 1] Annulation of Benzamides: Cyclopropenes as One-Carbon Synthons
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https://pubs.acs.org/doi/10.1021/jacs.4c16953
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April 28, 2025
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Researches aimed to explore the use of cyclopropenes as coupling partners in the annulation of benzamides under CpxCoIII catalysis. For that purpose, they investigated the production of a [4 + 1] annulated isoindolinone (3aa) through an annulation reaction with N-chlorobenzamide (1a), a 3,3-disubstituted cyclopropene (with -CH3 and benzene groups as substituents) (2a), carbonyldiiodo(pentamethylcyclopentadienyl)cobalt(III) (Cp*Co(CO)I2), silver triflate (AgOTf), and sodium acetate (NaOAc), in 1,2-dichloroethane (DCE) and 2,2,2-Trifluoroethanol (TFE).
N-chlorobenzamide (0.05 mmol, 1 eq.) (1a), (Cp*Co(CO)I2) catalyst (10 mol%), AgOTf (20 mol%), and NaOAc ( 1.2 equiv) were added to an oven-dried 5 mL microwave tube. The reaction vessel was evacuated with vacuum and refilled with nitrogen (3 cycles) while connected to Schlenk line. Degassed trifluoroethanol (0.35 mL) was added and stirred for 5 - 10 min, cyclopropene 2a (2 eq.) was dissolved in degassed dichloroethane (0.15 mL) and added to the vessel (TFE:DCE → 7:3 (0.1 M). The reaction mixture was stirred at 30 ºC for 36 hours. Acetic acid (0.1 mL) and ethylacetate (0.5 mL) were added for quenching the reaction mixture, which was afterwards stirred for 10 min at 23 °C, and filtered using silica gel. The resulting crude reaction mixture was analyzed by quantitative NMR with 1,3,5-trimethoxy benzene as the internal standard, and the reaction yield (%) of the annulated isoindolinone (3aa) was determined.
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- Reaction yield (%) of the [4+1] annulated isoindolinone (3aa) (quantitative NMR).
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Researchers investigated the production of a [4 + 1] annulated isoindolinone (3aa) through an annulation reaction with N-chlorobenzamide (0.05 mmol, 1 eq.) (1a), a 3,3-disubstituted cyclopropene (with -CH3 and benzene groups as substituents) (2 eq.) (2a), Cp*Co(CO)I2 as catalyst (10 mol%), silver triflate (AgOTf) (20 mol%), and sodium acetate (NaOAc) (1.2 equiv), in 1,2-dichloroethane (DCE) and 2,2,2-Trifluoroethanol (TFE) (TFE:DCE → 7:3 (0.1 M), at 30 ºC for 36 hours. The reaction mixture was analyzed by quantitative NMR with 1,3,5-trimethoxy benzene as the internal standard, and the reaction yield (%) of the annulated isoindolinone (3aa) was determined. What is the expected yield (%) of the annulated isoindolinone (3aa) product?
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Reaction yield (3aa) = 31- 41 %. Note: No CI/SE/SD reported → Fallback ± 5 percent points applied over the value of 36 %.
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- Cyclopropenes are strained unsaturated cycles and are valuable synthetic building blocks with diverse reactivity profiles.
- CoIII complexes bearing chiral cyclopentadienyl (Cpx) ligands are highly selective transition-metal catalysts for enantioselective C–H functionalization.
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[{"label":"RBK Item","value":"- Cyclopropenes are strained unsaturated cycles and are valuable synthetic building blocks with diverse reactivity profiles."},{"label":"Title","value":"Recent developments in cyclopropene chemistry"},{"label":"URL","value":"https://pubs.acs.org/doi/10.1021/jacs.9b02569"},{"label":"Date","value":"May 2, 2020"},{"label":"Justification (\"Paywalled\", \"OA\", \"Other (justify)\")","value":"Paywalled version is the one cited for the given RBK item in this paper."},{"label":"RBK Item","value":"- CoIII complexes bearing chiral cyclopentadienyl (Cpx) ligands are highly selective transition-metal catalysts for enantioselective C–H functionalization."},{"label":"Title","value":"Chiral Cyclopentadienyl Cobalt(III) Complexes Enable Highly Enantioselective 3d-Metal-Catalyzed C–H Functionalizations"},{"label":"URL","value":"https://pubs.acs.org/doi/10.1021/jacs.9b02569"},{"label":"Date","value":"March 22, 2019\n"},{"label":"Justification (\"Paywalled\", \"OA\", \"Other (justify)\")","value":"Paywalled version is the one cited for the given RBK item in this paper"}]
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Chemistry
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Materials Chemistry / Catalysis
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Free-Format Question
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CO2 methanation with MOF-derived hierarchically porous spherical carbon nanocomposite incorporating cobalt nanoparticles
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https://chemrxiv.org/engage/chemrxiv/article-details/68ee235abc2ac3a0e0e2a488
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September 08, 2025
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Researchers synthesized and tested various carbon-based cobalt-containing nanocomposites as catalysts for the methanation of carbon dioxide.
To synthesize the nanocomposites, 0.395 g of cobalt(II) acetylacetonate (Co(II)(acac)2 (1.53 mmol) was dissolved in N,N’-dimethylformamide ([DMF] 60 mL) in a Teflon reaction vessel under ambient atmosphere. Subsequently, 0.446 g 2,6-naphthalene dicarboxylic acid (2.06 mmol) was added, the reaction was vessel placed into a microwave reactor, and the reaction mixture was heated to 160 ºC under microwave irradiation (microwave power: 60 %; 360 W). The reaction was stopped after 40 minutes and once cooled to 50 ºC, the resulting precipitate was filtered on a Büchner funnel and washed with chloroform. The powder product was oven-dried at 80 ºC, and the as-prepared product was carbonized at 600 ºC or 700 ºC in a tubular furnace for 2 hours under argon atmosphere (heating ramp of 5 ºC/min) The resulting catalysts are denoted as CoNDC-600 and CoNDC-700, according to the carbonization temperature employed.
A CO2 methanation assay was performed to assess CoNDC-600 and CoNDC-700 CO2 methanation performance. For this purpose, a continuous flow fixed-bed reactor (stainless steel tube; 6 mm internal diameter) was loaded with 100 mg of the corresponding catalyst (CoNDC-600 or CoNDC-700), and catalysts were subject to 400 ºC for 1 h under 20 mL/min of 50% (v/v) H2 diluted in Ar. Following 1 h purge with Ar and cooling down to 200 ºC, 10% CO2 and 40% H2 diluted in Ar was introduced into the reactor at 20 mL/min, and the reaction proceeded in step mode, from 200 ºC to 400 ºC, with 50 ºC temperature increments, at atmospheric pressure. At least four gas chromatography (GC) injections were performed at each temperature step, after reaching a steady state. A SCION 456-GC chromatograph equipped with Hayesep Q, Molsieve 5A, Porapak R, and SCION-1 columns was employed to analyze the outlet gases. A thermal conductivity detector was employed to quantify CO and CO2, while a flame ionization detector was used to quantify CH4. All gas transfer lines were maintained at 125 ºC. CO2 conversion [(XCO2); (%)] was calculated according to: XCO2(%) = [(FCO2,in − FCO2,out)/FCO2,in] × 100%; where F is the molar flow rate.
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- CO2 conversion [(XCO2); (%)] by CoNDC-600 and CoNDC-700 at 200, 250, 300, 350 and 400 ºC (CO2 methanation assay).
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Researchers synthesized and tested various carbon-based cobalt-containing as catalysts for the methanation of carbon dioxide. To synthesize the nanocomposites, cobalt(II) acetylacetonate (Co(II) and 2,6-naphthalene dicarboxylic acid were dissolved in DMF and reacted into a microwave reactor (160 ºC; microwave power: 60 %; 360 W) during 40 minutes. Once cooled to 50 ºC, the resulting precipitate was filtered, washed with chloroform, oven-dried at 80 ºC, and carbonized at either 600 ºC or 700 ºC for 2 hours (Ar atmosphere; 5 ºC/min); the resulting catalysts being denoted as CoNDC-600 and CoNDC-700, according to the corresponding carbonization temperatures. The CO2 methanation performance of CoNDC-600 and CoNDC-700 was determined in a continuous flow fixed-bed reactor loaded with 100 mg of the corresponding catalyst. After in situ catalysts pre-treatment (400 ºC, 1 h, 20 mL/min 50% (v/v) H2 in Ar), Ar purge and cooling to 200 ºC, 20 mL/min reaction mixture (10% CO2 and 40% H2 in Ar) was introduced into the reactor and the reaction proceeded at atmospheric pressure from 200 ºC to 400 ºC in step mode, with 50 ºC temperature increments, and products and reactants were monitored by gas chromatography. The CO2 conversion [(XCO2); (%)] was calculated according to: XCO2(%) = [(FCO2,in − FCO2,out)/FCO2,in] × 100%; where F is the molar flow rate. What is the expected XCO2(%) for CoNDC-600 and CoNDC-700 at 350 ºC?
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XCO2 [CoNDC-600; 350 ºC] = 65 - 75 %; XCO2 [CoNDC-700; 350 ºC] = 58 - 68 %. Note: no CI/SE/SD reported → fallback ± 5 percent points applied to the values of 70 % [CoNDC-600] and 63 % [CoNDC-700].
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- The CO2 methanation reaction is the process of converting carbon dioxide (CO₂) and hydrogen (H₂) into methane (CH₄), serving as a carbon recycling route that aligns with sustainable energy goals.
- Cobalt nanoparticles are catalysts for CO2 methanation, with cobalt oxide (CoO) promoting the hydrogenation of CO2 to CO or hydrocarbons, and and metallic cobalt (Co) promoting the hydrogenation of CO2 to CH4.
- Metal-organic framework (MOF)-derived cobalt carbon composite catalysts are functional materials with applications in heterogeneous thermocatalysis [18, 19]: Metal-Organic Framework–Specific Catalysis; https://chemistry-europe.onlinelibrary.wiley.com/doi/10.1002/cctc.202402102; February 19, 2025; OA.
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[{"label":"RBK Item","value":"- The CO2 methanation reaction is the process of converting carbon dioxide (CO₂) and hydrogen (H₂) into methane (CH₄), serving as a carbon recycling route that aligns with sustainable energy goals.\n"},{"label":"Title","value":" Recent Advancements, Fundamental Challenges, and Opportunities in Catalytic Methanation of CO2"},{"label":"URL","value":"https://pubs.acs.org/doi/10.1021/acs.energyfuels.6b01723"},{"label":"Date","value":"October 18, 2016"},{"label":"Justification (\"Paywalled\", \"OA\", \"Other (justify)\")","value":"Paywalled version is the RBK item cited by this paper"},{"label":"RBK Item","value":"- Cobalt nanoparticles are catalysts for CO2 methanation, with cobalt oxide (CoO) promoting the hydrogenation of CO2 to CO or hydrocarbons, and and metallic cobalt (Co) promoting the hydrogenation of CO2 to CH4.\n"},{"label":"Title","value":"CO2 hydrogenation over cobalt-containing catalysts"},{"label":"URL","value":"https://link.springer.com/article/10.1134/S0023158415050183"},{"label":"Date","value":"September 23, 2015"},{"label":"Justification (\"Paywalled\", \"OA\", \"Other (justify)\")","value":"Paywalled version is the RBK item cited by this paper"},{"label":"RBK Item","value":"- Metal-organic framework (MOF)-derived cobalt carbon composite catalysts are functional materials with applications in heterogeneous thermocatalysis.\n"},{"label":"Title","value":"Metal-Organic Framework–Specific Catalysis"},{"label":"URL","value":"https://chemistry-europe.onlinelibrary.wiley.com/doi/10.1002/cctc.202402102"},{"label":"Date","value":"February 19, 2025"},{"label":"Justification (\"Paywalled\", \"OA\", \"Other (justify)\")","value":"OA"}]
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Chemistry
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Nanomaterials Chemistry
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Numerical Values
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Pathway-Resolved Hierarchical Self-Assembly of Biomimetic Double-Walled Nanotubes
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https://chemrxiv.org/engage/chemrxiv/article-details/68e3c106bc2ac3a0e09c2f71
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October 9, 2025
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Researchers studied in real time the formation of double-walled nanotubes (DWNTs) from the amphiphilic cyanine dye C8S3 (3,3′-bis(2-sulfopropyl)-5,5′,6,6-tetrachloro-1,1′-dioctylbenzimidacarbocyanine; MW = 903 g/mol). For this purpose, 2 mg of C8S3 were dissolved in 4 mL of methanol, resulting in a stock concentration of 0.55 mM. Self-assembly was initiated by manually mixing the stock solution with water in a cuvette at a stock-to-water volume ratio of 1:2.5. Absorption spectra were recorded at various time points after mixing (first at 15 s, 40 s, and 60 s; followed by subsequent measurements at 30 s intervals up to 10 min, and a final measurement after 1440 min (24h)) using a PerkinElmer Lambda 900 UV/Vis/NIR spectrometer. The narrow peaks at ~ 589 nm and ~ 599 nm were assigned to the outer and inner nanotubes (NTs) of DWNTs, respectively. To estimate the fraction of molecules residing in the inner and outer NTs, the ratio of the maximum optical density (OD) of the inner NT (~ 599 nm) to the outer NT (~ 589 nm) (ODmax[outer/inner] = [ODmax ~ 589 nm, outer]/[ODmax ~ 599 nm, inner]) was calculated (at the different indicated times after mixing.
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- UV-Visible absorption spectra of the 1:2.5 C8S3:water solution 15 s, 40 s, 60 to 600 s (30 s increments), and 24h after mixing (PerkinElmer Lambda 900 UV/Vis/NIR spectrometer).
- Ratio ODmax[outer/inner] = ODmax at ~589 nm (outer NT) divided by ODmax at ~599 nm (inner NT), evaluated at 15 s, 40 s, 60–600 s (30 s increments), and 24 h after mixing.
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Researchers studied the real-time formation of C8S3 (3,3′-bis(2-sulfopropyl)-5,5′,6,6-tetrachloro-1,1′-dioctylbenzimidacarbocyanine) double-walled nanotubes (DWNTs). For this purpose, a 0.55 mM C8S3 solution in methanol was manually mixed with water at 1:2.5 ratio (C8S3:water) to initiate self-assembly, and absorption spectra were recorded at 15 s, 40 s, 60 to 600 s (30 s increments), and 24h after mixing, using a PerkinElmer Lambda 900 UV/Vis/NIR spectrometer. The fraction of molecules residing in the inner and outer nanotubes (NTs) was estimated by the ratio of the maximum optical density of the inner NT (~ 599 nm) to the outer NT (~ 589 nm) (ODmax[outer/inner] = [ODmax ~ 589 nm, outer]/[ODmax ~ 599 nm, inner]), calculated for the different measured times after mixing. What is the predicted value of the ODmax[outer/inner] measured 24h after mixing?
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ODmax[outer/inner] = 1.5 → [1.35 - 1.65]. Note: no CI/SE/SD reported → fallback ± 10% applied.
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- Molecular self-assembly is the spontaneous organization of disordered molecular components into ordered, functional structures without external guidance.
- Carbocyanine dyes such as C8S3 are able to form double-walled nanotubes (DWNTs) through self-assembly.
- Double-walled nanotubes DWNTs are characterized by narrow excitonic peaks around 589 nm and 599 nm, which have been attributed to the lower-energy exciton transitions of the outer and inner nanotubes.
|
[{"label":"RBK Item","value":"- Molecular self-assembly is the spontaneous organization of disordered molecular components into ordered, functional structures without external guidance.\n"},{"label":"Title","value":"Replicating shear-mediated self-assembly of spider silk through microfluidics"},{"label":"URL","value":"https://www.nature.com/articles/s41467-024-44733-1"},{"label":"Date","value":"January 15, 2024"},{"label":"Justification (\"Paywalled\", \"OA\", \"Other (justify)\")","value":"OA"},{"label":"RBK Item","value":"- Carbocyanine dyes such as C8S3 are able to form double-walled nanotubes (DWNTs) through self-assembly.\n"},{"label":"Title","value":"Synthesis and UV/Vis Spectra of J-Aggregating 5,5′,6,6′-Tetrachlorobenzimidacarbocyanine Dyes for Artificial Light-Harvesting Systems and for Asymmetrical Generation of Supramolecular Helices"},{"label":"URL","value":"https://chemistry-europe.onlinelibrary.wiley.com/doi/abs/10.1002/ejoc.200300095"},{"label":"Date","value":"July 22, 2003"},{"label":"Justification (\"Paywalled\", \"OA\", \"Other (justify)\")","value":"Paywalled version is the one cited by the paper"},{"label":"RBK Item","value":"- Double-walled nanotubes DWNTs are characterized by narrow excitonic peaks around 589 nm and 599 nm, which have been attributed to the lower-energy exciton transitions of the outer and inner nanotubes."},{"label":"Title","value":"Utilizing redox-chemistry to elucidate the nature of exciton transitions in supramolecular dye nanotubes"},{"label":"URL","value":"https://www.nature.com/articles/nchem.1380"},{"label":"Date","value":"July 1, 2012"},{"label":"Justification (\"Paywalled\", \"OA\", \"Other (justify)\")","value":"Paywalled version is the one cited by the paper"}]
|
Chemistry
|
Biological chemistry
|
MCQ
|
The ASNS inhibitor ASX-173 potentiates L-asparaginase anticancer activity
|
https://www.biorxiv.org/content/10.1101/2025.07.03.662851v1
|
July 7, 2025
|
The cell lines were prepared as follows: MTT Assays were used to prepare adherent cells, which were seeded in 96-well black, clear-bottom plates. These cells were left overnight to attach to the plate before they were treated with ASX-173, L-asparaginase (ASNase), or a combination of both. After treating the cells with ASX-173, ASNase, or the combination, they were left for 72 hours, where the MTT reagent (Sigma, M5655) (0.50 mg/mL) was added, before incubating the cells for 4 hours. Afterwards, the plates were centrifuged (550 × g, 12 min, 4°C), followed by the removal of supernatants and the addition of DMSO (100 μL) per well. Next, the plates were shaken for one hour at room temperature, then the absorbance was measured at 570 nm. Blanks without MTT assay were also used for background subtraction. Finally, wells with the control treatment were set to 100% to calculate the IC50 values using GraphPad Prism 8.0.
Suspension cells were also attempted to be prepared in the MTT assay, similarly as mentioned above, but had to undergo rapid treatments of ASX-173, ASNase, or a combination of both.
On the other hand, the Resazurin assay was used more for preparing suspension cells, where these cells were seeded and treated as mentioned in the MTT assay. After 72 hours, resazurin reagent (Sigma, R7017) was added (40 μM) and incubated for 4 to 6 hours. Fluorescence was measured (Ex: 560 nm, Em: 590) on this assay to determine the IC50 values of ASX-173, as calculated in the MTT assay.
|
- Absorbance measurement at 570 nm, to determine the IC50 values of ASX-173
- Fluorescence measurement (Ex: 560 nm, Em: 590), to determine the IC50 values of ASX-173
- IC50 nanomolar concentrations of ASX-173 were tested against cancer cell lines ASPC1, H1299, CaCo2, HPF-hTERT, HT1080, RKO, HCT116, HT29, MDA-MB-231, SW620, MCF7, A375, and A172 with an Asn-free medium.
- IC50 nanomolar concentrations of ASX-173 were tested against cancer cell lines B16, H929, THP1, 4T1, OPM-2, AMO1, MOLP8, H1299, Jurkat, and MV4;11 with an Asn-depleted medium.
|
The anticancer small molecule drug ASX-173 can potentiate the anticancer activity of L-asparaginase, which may be a potential cancer therapy for acute lymphoblastic leukaemia (ALL). ASX-173 and L-asparaginase help inhibit the asparagine metabolism, an essential function in ALL cells. Excluding the use of L-asparginase anticancer activity, ASX-173 acts as a potent and selective asparagine synthetase (ASNS) at concentrations of 6 – 500 nM. Based on the broad-spectrum anticancer activity of ASX-173 against this panel of cancer cell lines: RKO, A375, ASPC1, and SW620, which of these cell lines treated with Asn-free medium shows the highest anticancer activity of ASX-173?
A) Cell line RKO
B) Cell line A375
C) Cell line ASPC1
D) Cell line SW620
|
B) Cell Line A375
|
-Acute lymphoblastic leukaemia (ALL) is the most common cancer found in children. In 2015, an estimated 6000 new cases of ALL were diagnosed every year in the United States of America, where 60 % of cases are children aged younger than 20 years old.
-L-asparaginase (ASNase) was the first treatment for childhood acute lymphoblastic leukaemia (ALL) that showed potential for cancer therapy by targeting asparagine metabolism in cancer cells.
-Asparagine synthetase (ASNS) is an enzyme that upregulates asparagine metabolism in cancer cells. This metabolism serves to drive cell proliferation, chemoresistance, and metastasis in these cells.
-ASX-173 is a small molecule which was shown to have superior cell permeability, target specificity, and potency. Furthermore, its combination with ASNase achieves further blockade of asparagine.
|
[{"label":"RBK Item","value":"Acute lymphoblastic leukaemia (ALL) is the most common cancer found in children. In 2015, an estimated 6000 new cases of ALL were diagnosed every year in the United States of America, where 60 % of cases are children aged younger than 20 years old."},{"label":"Title","value":"Asparaginase Therapy in Pediatric Acute Lymphoblastic Leukemia: A Focus on the Mode of Drug Resistance"},{"label":"URL","value":"https://www.sciencedirect.com/science/article/pii/S1875957214001983"},{"label":"Date","value":"December 23, 2014"},{"label":"Justification (\"Paywalled\", \"OA\", \"Other (justify)\")","value":"OA"},{"label":"RBK Item","value":"L-asparaginase (ASNase) was the first treatment for childhood acute lymphoblastic leukaemia (ALL) that showed potential for cancer therapy by targeting asparagine metabolism in cancer cells."},{"label":"Title","value":"Asparaginase in Acute Lymphoblastic Leukemia"},{"label":"URL","value":"https://www.clinical-lymphoma-myeloma-leukemia.com/article/S2152-2650(14)00172-4/abstract"},{"label":"Date","value":"September, 2014"},{"label":"Justification (\"Paywalled\", \"OA\", \"Other (justify)\")","value":"Paywalled"},{"label":"RBK Item","value":"Asparagine synthetase (ASNS) is an enzyme that upregulates asparagine metabolism in cancer cells. This metabolism serves to drive cell proliferation, chemoresistance, and metastasis in these cells."},{"label":"Title","value":"Asparaginase Therapy in Pediatric Acute Lymphoblastic Leukemia: A Focus on the Mode of Drug Resistance"},{"label":"URL","value":"https://www.sciencedirect.com/science/article/pii/S1875957214001983"},{"label":"Date","value":"December 23, 2014"},{"label":"Justification (\"Paywalled\", \"OA\", \"Other (justify)\")","value":"OA"}]
|
Chemistry
|
Catalysis
|
MCQ
|
Catalytic quantitative formation of gamma-valerolactone from furfural aldehyde by PNP-Ru catalyst under a H2 atmosphere with a recyclable acidic system
|
https://chemrxiv.org/engage/chemrxiv/article-details/68f2530ebc2ac3a0e08e72e5
|
October 21, 2025
|
Researchers investigated the catalytic conversion of furfural aldehyde (FA) to γ-valerolactone (GVL) using a homogeneous ruthenium PNP-type catalyst under a hydrogen atmosphere. The reaction medium consisted of ethanol–water mixtures with varying solvent ratios (0–100% EtOH). The primary hydrogenation catalyst was Ru-MACHO-BH (Ru-2), used at 2 mol% loading, with Amberlyst-36 resin (5 mol%) as the recyclable acidic co-catalyst. Reactions were performed under 30 bar H₂ pressure at 120 °C for 24 hours. Catalyst and acid concentrations, solvent composition, temperature, and reaction duration were systematically varied to evaluate their influence on GVL yield and selectivity. Product yields and conversions were determined by nuclear magnetic resonance (NMR) spectroscopy.
|
* Product yields and selectivity for the GVL formation route, determined by nuclear magnetic resonance (NMR) spectroscopy.
|
Researchers examined the hydrogenation of furfural aldehyde (FA) to γ-valerolactone (GVL) using the Ru-MACHO-BH (Ru-2) 2 mol% catalyst with 5 mol% Amberlyst-36 under 30 bar H₂ at 120 °C for 24 hours. Reactions were performed with varying solvent compositions (EtOH:H₂O = 10:0, 9.5:0.5, 7:3, 5:5).
What is the optimal solvent ratio of EtOH to H₂O, among the options provided, that will result in the quantitative 100% yield of gamma-valerolactone (GVL) when using 2 mol% Ru-2 and 5 mol% Amberlyst-36 at 120 °C for 24 hours under 30 bar H₂?
A. 9.5:0.5 EtOH:H₂O
B. 10:0 EtOH:H₂O
C. 7:3 EtOH:H₂O
D. 5:5 EtOH:H₂O
|
B. 10:0 EtOH:H₂O
|
* Furfural aldehyde (FA) is a biogenic compound derived from carbohydrate sources such as xylose and hemicellulose.
* γ-Valerolactone (GVL) is a chemical product that can be generated from furfural under reductive and acidic conditions.
|
[{"label":"RBK Item","value":"Furfural aldehyde (FA) is a biogenic compound derived from carbohydrate sources such as xylose and hemicellulose."},{"label":"Title","value":"Furfural: A Sustainable Platform Chemical and Fuel"},{"label":"URL","value":"https://ojs.kmutnb.ac.th/index.php/ijst/article/view/2509"},{"label":"Date","value":"January 21, 2020"},{"label":"Justification (\"Paywalled\", \"OA\", \"Other (justify)\")","value":"OA"},{"label":"RBK Item","value":"γ-Valerolactone (GVL) is a chemical product that can be generated from furfural under reductive and acidic conditions."},{"label":"Title","value":"Green Polymer Precursors from Biomass-Based Levulinic Acid"},{"label":"URL","value":"https://www.sciencedirect.com/science/article/pii/S187661961200037X"},{"label":"Date","value":"August 8, 2012"},{"label":"Justification (\"Paywalled\", \"OA\", \"Other (justify)\")","value":"OA"}]
|
Chemistry
|
Organic Chemistry
|
MCQ
|
An Inverse Electron-Demand Diels−Alder Approach to Selective Activity-Based Sensing of Acetaldehyde in Living Cells
|
https://pubs.acs.org/doi/10.1021/jacs.5c14058
|
October 10, 2025
|
The researchers synthesized acetaldehyde probes (AAPs) through the condensation of a coumarin-derived nitrile and Boc-protected 2-(pyrrolidin-2-yl)acetonitrile in the presence of hydrazine, followed by the Boc deprotection. 9-Methyl-10-(3-(6-(pyrrolidin-2-ylmethyl)-1,2,4,5-tetrazin-3-yl)phenyl)-2,3,6,7-tetrahydro-1H,5H, 11H-pyrano[2,3-f]pyrido[3,2,1-ij]quinolin-11-one (Acetaldehyde Probe-1, AAP-1), 9-Methyl-10-(3-(6-(pyrrolidin-2-ylmethyl)-1,2,4,5-tetrazin-3-yl)phenyl)-2,3,6,7-tetrahydro-1H,5H, 11H-pyrano[2,3-f]pyrido[3,2,1-ij]quinolin-11-one (Acetaldehyde Probe-2, AAP-2), (E)-9-Methyl-10-(2-(6-(pyrrolidin-2-ylmethyl)-1,2,4,5-tetrazin-3-yl)vinyl)-2,3,6,7-tetrahydro-1H,5H, 11H-pyrano[2,3-f]pyrido[3,2,1-ij]quinolin-11-one (Acetaldehyde Probe-3, AAP-3) were obtained.
Fluorescence turn-on responses of AAP were monitored at different time points. In detail, 100 μM AAP was dissolved in HBSS (pH 7.4) containing 5% DMSO at 37°C, made from a DMSO stock of the probe. Meanwhile, acetaldehyde stock was made by diluting 5 M stock solution in THF (commercial stock) in HBSS (pH 7.4) containing 5% DMSO. After adding acetaldehyde solution to bring the concentration of acetaldehyde to 1 mM, the fluorescence signals were monitored at 0 min, 30 min, 60 min, 90 min, and 120 min. The excitation wavelength was 410 nm, and the emission data was collected between 450-600 nm.
Yields of reactions of AAP-1, AAP-2, and AAP-3 with acetaldehyde were determined by integration of LC-MS signals at 254 nm.
|
-Yields of reactions of AAP-1, AAP-2, and AAP-3 with acetaldehyde were determined by integration of LC-MS signals at 254 nm.
|
Acetaldehyde (AA) is a highly reactive carbon compound of physiological relevance and researchers have developed chemical tools to measure its concentration in solution as well as in living cells. AAP-1, AAP-2, and AAP-3 were synthesized through the condensation of a coumarin-derived nitrile and Boc-protected 2-(pyrrolidin-2-yl)-
acetonitrile in the presence of hydrazine, followed by the Boc deprotection. Based on the use of these probes targeting acetaldehyde, which of the following outcomes is most likely?
A. AAP-1 has the highest yield targeting acetaldehyde across the time
B. AAP-2 has the highest yield targeting acetaldehyde across the time
C. AAP-3 displays markedly different behavior compared to AAP-1 and AAP-2
D. A and C are both correct
|
D. A and C are both correct
|
- Acetaldehyde (AA) is a highly reactive and toxic two-carbon metabolite that can cause extensive cellular damage when not efficiently metabolized. It readily forms covalent adducts with DNA, proteins, and lipids, leading to impaired biomolecular function, oxidative stress, and genomic instability and ultimately promoting carcinogenesis
- The precise monitoring of aldehydes has emerged as a critical area of research for elucidating their roles in various disease processes, with activity-based sensing (ABS) as a powerful approach toward this end
- Despite notable progress in the field, the selective monitoring of acetaldehyde, a major product of ethanol metabolism, remains elusive
|
[{"label":"RBK Item","value":"Acetaldehyde (AA) is a highly reactive and toxic two-carbon metabolite that can cause extensive cellular damage when not efficiently metabolized. It readily forms covalent adducts with DNA, proteins, and lipids, leading to impaired biomolecular function, oxidative stress, and genomic instability and ultimately promoting carcinogenesis"},{"label":"Title","value":"Aldehyde-induced DNA-protein crosslinks- DNA damage, repair and mutagenesis"},{"label":"URL","value":"https://pubmed.ncbi.nlm.nih.gov/39328207/"},{"label":"Date","value":"September 12, 2024"},{"label":"Justification (\"Paywalled\", \"OA\", \"Other (justify)\")","value":"OA"},{"label":"RBK Item","value":"The precise monitoring of aldehydes has emerged as a critical area of research for elucidating their roles in various disease processes, with activity-based sensing (ABS) as a powerful approach toward this end"},{"label":"Title","value":"Activity-Based Sensing: A Synthetic Methods Approach for Selective Molecular Imaging and Beyond"},{"label":"URL","value":"https://pubmed.ncbi.nlm.nih.gov/31605413/"},{"label":"Date","value":"August 10, 2020"},{"label":"Justification (\"Paywalled\", \"OA\", \"Other (justify)\")","value":"OA"},{"label":"RBK Item","value":"Despite notable progress in the field, the selective monitoring of acetaldehyde, a major product of ethanol metabolism, remains elusive"},{"label":"Title","value":"Imaging Acetaldehyde Formation During Ethanol Metabolism in Living Cells using a Hydrazinyl Naphthalimide Fluorescent Probe"},{"label":"URL","value":"https://pubmed.ncbi.nlm.nih.gov/29109756/"},{"label":"Date","value":"May 29, 2017"},{"label":"Justification (\"Paywalled\", \"OA\", \"Other (justify)\")","value":"OA"}]
|
Chemistry
|
Inorganic Chemistry, Spectroscopy
|
Numerical Values
|
Quantifying the Lewis Acidity of Mono-, Di-, and Trivalent Cations in Anhydrous Bis(trifluoromethylsulfonyl)imide Salts
|
https://chemrxiv.org/engage/chemrxiv/article-details/688a460d23be8e43d6e7a94f
|
August 01, 2025
|
Researchers organized a series of experiments by titration in anhydrous acetonitrile (CH₃CN) to quantify and compare the effective Lewis acidity of the sodium cation (Na⁺) when paired with different weakly coordinating anions. The experiments used a modified methodology using oxide of triphenylphosphine (TPPO) as a spectroscopic probe. Each titration started with a 10 mM solution of triphenylphosphine. To this solution, increasing amounts of either sodium trifluoromethanesulfonate (NaOTf), sodium bis(trifluoromethylsulfonyl)imide (NaTFSI), sodium hexafluorophosphate (NaPF₆), or sodium tetrakis[3,5-bis(trifluoromethyl)phenyl]borate (NaBArF₂₄)—were dropped, resulting in normality between 0 and 20N. The interaction between the Na⁺ cation and the Lewis oxygen (basic) atom of TPPO was monitored using ³¹P{¹H} Nuclear Magnetic Resonance (NMR) spectroscopy, which recorded the variation in the shift of the phosphorus nucleus. For each salt, the resulting titration data, plotting the change in the ³¹P chemical shift versus the equivalent proportions of added Sodium cation salt, were fitted to a 1:1 binding isotherm model. This analysis assumed the formation of a single, dominant 1:1 in ratio adduct between TPPO and the cation. All experiments were conducted in inert atmosphere at 298K (room temperature) and all chemicals were dried with heat and vacuum prior to use.
|
- Change in the ³¹P NMR chemical shift ($Δδ^{31}P$) of TPPO as a function of the equivalents of added sodium salt (NaOTf, NaTFSI, NaPF₆, or NaBArF₂₄).
- Association constant (Kₐ) for the formation of the 1:1 TPPO-cation bound complex, derived from fitting the titration data to Langmuir type isotherm.
- Maximum change in the ³¹P NMR chemical shift of TPPO at infinite excess of cation ($Δδ_{max}^{31}P$), derived from fitting the titration data.
|
Researchers conducted titrations of ³¹P NMR of a 10 mM triphenylphosphine oxide (TPPO) solution in acetonitrile with various salts of sodium to quantify the effective Lewis acidity of the Sodium cation. The titration data for each salt were fitted to a 1:1 in ratio binding isotherm to determine the maximum change in the ³¹P chemical shift at saturation ($Δδ_{max}^{31}P$). What would be the difference (in ppm) in the $Δδ_{max}^{31}P$ value between the sodium hexafluorophosphate (NaPF₆) salt and the sodium trifluoromethanesulfonate (NaOTf) salt?
|
0.88-1.12 ppm
|
- Lewis Acidity is the ability of a chemical species, such as a metal cation, to act as an electron-pair acceptor. It is quantified by the strength of the electrostatic interaction between the cation and an electron-pair donor.
- Weakly Coordinating Anion is an anion with a delocalized negative charge, designed to have minimal interaction with its corresponding cation. The use of WCAs allows the cation to express its intrinsic Lewis acidity more fully.
-The anions studied include sulfonyl-based OTf⁻ and TFSI⁻, and the generally weaker coordinating P- and B-based PF₆⁻ and BArF₂₄⁻.
- ³¹P NMR Probe (TPPO) is where Triphenylphosphine oxide (TPPO) serves as a ³¹P NMR probe, as its Lewis basic oxygen atom can donate electron density to a cation. This interaction causes a downfield shift in its ³¹P NMR signal proportional to the Lewis acid's strength.
-The Gutmann-Beckett methodology is a standard technique for quantifying Lewis acidity. It measures the change in the ³¹P NMR chemical shift of a phosphine oxide probe, where a larger downfield shift indicates a stronger Lewis acidic interaction.
- 1:1 Binding Isotherm is a mathematical model describing a chemical equilibrium where one molecule of a probe (TPPO) binds to one cation (Na⁺). Fitting experimental titration data to this model yields key thermodynamic and spectroscopic parameters.
- Maximum Chemical Shift ($Δδ_{max}^{31}P$) is a parameter from the binding isotherm fit representing the theoretical chemical shift change when the probe is fully bound to the cation. A larger $Δδ_{max}^{31}P$ value indicates a more electron-poor cation, implying a less coordinating, or weaker, counter-anion.
|
[{"label":"RBK Item","value":"-The Gutmann-Beckett methodology is a standard technique for quantifying Lewis acidity. It measures the change in the ³¹P NMR chemical shift of a phosphine oxide probe, where a larger downfield shift indicates a stronger Lewis acidic interaction."},{"label":"Title","value":"Molecular Influences on the Quantification of Lewis Acidity with Phosphine Oxide Probes"},{"label":"URL","value":"https://pubmed.ncbi.nlm.nih.gov/36943934/"},{"label":"Date","value":"March 21, 2023"},{"label":"Justification (\"Paywalled\", \"OA\", \"Other (justify)\")","value":"OA"}]
|
Chemistry
|
Materials Chemistry
|
Free-Format Question
|
Fast-Track Remediation: N-Doped Carbon Derived from Banana Stem for Efficient Water Treatment
|
https://chemrxiv.org/engage/chemrxiv/article-details/6889e17dfc5f0acb52cf26f2
|
August 1, 2025
|
Researchers explored the development of hierarchical porous nitrogen-doped carbon (HPNC) materials synthesized from banana plant stems (Musa acuminata). Banana stems were washed, peeled, sliced, sun-dried, and ground into powder. Banana stem powder (7 g) was placed into a 100 mL Teflon-lined autoclave filled with distilled water (70 mL), and subject to 150ºC for 10 hours in a hot air oven. The resulting product was washed with distilled water and dried at 100 ºC, rendering carbonized banana stem powder. Urea and carbonized banana stem powder (a 1:1 mass ratio) were mixed and treated at 400°C for 1 hour in a muffle furnace. The product was mixed with KOH powder in a 1:1 mass ratio, and further processed for 1 hour in a tubular furnace under an inert nitrogen atmosphere at 400, 550, 700, and 800°C. The resultant products were washed with HCl (0.01M) solution and with distilled water until reaching a neutral pH. The product was dried afterwards at 80°C for 12 h in a hot air oven. The prepared samples were labelled as HPNC- followed by the corresponding temperature value (ºC) employed in the last thermal processing step (i.e. HPNC-400, HPNC-550, HPNC-700, and HPNC-800).
X-ray diffraction (XRD) spectra were obtained to determine the degree of graphitization (26.5º and 42.6º peaks), by subjecting the samples to phase analysis of using a Panalytical Xpert Pro X-ray diffractometer, with data collection ranging from 2θ = 10º to 80º and an increment of 0.025º with Cu Kα line with a wavelength of 0.154 nm.
|
- XRD spectra of HPNC-400, HPNC-550, HPNC-700, and HPNC-800 samples from 2θ = 10º to 80º (0.025º increment; Cu Kα line at 0.154 nm) (Panalytical Xpert Pro X-ray diffractometer).
|
Researchers explored the development of hierarchical porous nitrogen-doped carbon (HPNC) materials synthesized from banana plant stems (Musa acuminata). Banana stem powder (7g) was placed into a Teflon-lined autoclave filled with distilled water (70 mL), subject to 150ºC for 10 hours in a hot air oven, washed with distilled water and dried at 100 ºC, mixed with urea (1:1 mass ratio) and treated at 400°C for 1 hour in a muffle furnace, subsequently mixed with KOH powder (1:1 mass ratio), and further processed for 1 hour in a tubular furnace under an inert nitrogen atmosphere at 400, 550, 700, and 800°C temperatures. All resulting products were washed with HCl (0.01M) and distilled water (until neutral pH was reached), and dried afterwards at 80°C in a hot air oven for 12 h. Samples were labeled as HPNC-400, HPNC-550, HPNC-700, and HPNC-800; according to the temperature employed during the tubular furnace processing. X-ray diffraction (XRD) spectra were obtained from 2θ = 10º to 80º (0.025º increment; Cu Kα line at 0.154 nm). What is the expected outcome, regarding the degree of graphitization (26.5º and 42.6º XRD peaks), in relation with the increasing processing temperature of the samples (i.e. HPNC-400 vs HPNC-800)?
|
XRD spectra (26.5º and 42.6º XRD peaks) demonstrated a decrease of graphitization as the processing temperature increased from 400 to 800 ºC.
|
- Musa acuminata, commonly known as the banana plant, is a widely available agricultural byproduct in tropical and subtropical regions.
- The banana plant stem is rich in lignocellulosic content and carbon precursors, making it a promising raw material for activated carbon synthesis.
- Nitrogen-doped activated carbon is prepared by introducing nitrogen-containing functional groups into activated carbon, enhancing its adsorption property and surface features.
- The degree of graphitization of a material can be determined by the diffraction peaks found at 26.5º and 42.5º in their X-ray diffraction spectra.
|
[{"label":"RBK Item","value":"- Nitrogen-doped activated carbon is prepared by introducing nitrogen-containing functional groups into activated carbon, enhancing its adsorption property and surface features."},{"label":"Title","value":"Nitrogen-doped biochars as adsorbents for mitigation of heavy metals and organics from water: a review"},{"label":"URL","value":"https://link.springer.com/article/10.1007/s42773-022-00145-2"},{"label":"Date","value":"March 8, 2022"},{"label":"Justification (\"Paywalled\", \"OA\", \"Other (justify)\")","value":"OA"},{"label":"RBK Item","value":"- The degree of graphitization of a material can be determined by the diffraction peaks found at 26.5º and 42.5º in their X-ray diffraction spectra."},{"label":"Title","value":"Investigation of PF6− and TFSI− anion intercalation into graphitized carbon blacks and its influence on high voltage lithium ion batteries"},{"label":"URL","value":"https://pubs.rsc.org/en/content/articlelanding/2014/cp/c4cp04113e"},{"label":"Date","value":"October 14, 2014"},{"label":"Justification (\"Paywalled\", \"OA\", \"Other (justify)\")","value":"Paywalled version is the external reference cited by the paper"}]
|
Chemistry
|
Organometallic Chemistry
|
Free-Format Question
|
Reactivity of Gold and Copper Acetylide with a Secondary Borane
|
https://chemrxiv.org/engage/chemrxiv/article-details/68f19e1c5dd091524ff3efba
|
October 21, 2025
|
Researchers prepared an equimolar solution of Ph3PAuCCPh (32.1mg) and HBMeoCb2 (18.3mg) in 4mL toluene at 23°C.
Changes in the 11B, 1H and 31P NMR spectra were seen after 30 minutes of reaction under stirring, suggesting complete reaction. After full precursor consumption, vacuum drying and work up a new species (1) was isolated and studied by single crystal X-ray diffraction on crystals grown from n-pentane vapor diffusion into the concentrated toluene solution at -35°C .
Similarly, researchers prepared an equimolar solution of Ph3PCuCCPh (20.9mg) and HBMeoCb2(16.1mg) in 4mL toluene at 23 °C and monitored it by NMR spectroscopy.
Changes in the 11B, 1H and 31P NMR spectra were used to track the consumption of the two starting materials. The solution was stirred and allowed to react for 30 minutes and a species (2) was isolated. 2 was studied by single crystal x-ray diffraction on crystals grown from vapor diffusion of n-pentane into a concentrated dichloromethane solution at 23 °C.
|
• 11B, 1H and 31P NMR spectra of compounds 1 and 2
• Single crystal X-ray diffraction of crystallized compounds 1 and 2
• Structure determination (atomic arrangements, bond angles, and bond lengths) of 1 and 2
• Fourier transform infrared spectroscopy of compound 2
|
Researchers prepared two equimolar solutions of Ph3PAuCCPh/HBMeoCb2 (1) and Ph3PCuCCPh/HBMeoCb2 (2) respectively in 4mL toluene each at 23°C. 11B, 1H and 31P NMR spectra were collected to track the reaction progress. (1) was isolated and studied by single crystal X-ray diffraction on crystals grown from n-pentane vapor diffusion into the concentrated toluene solution at -35°C. 2 was studied by single crystal x-ray diffraction on crystals grown from vapor diffusion of n-pentane into a concentrated dichloromethane solution at 23 °C. What is the origin of the difference in the expected coordination and geometry between compound 1 and compound 2?
|
The gold complex can be considered an η2-coordinated 1-boratallene gold complex while the copper center is an alkynylborate complexed to CuPPh3+ via the alkyne.
A bridging hydride between boron and the Cu metal center suggests intermediates in the metal catalyzed hydroboration.
The difference between the geometries of compounds 1 and 2 originates from the smaller size of the Cu compared to Au and the superior affinity of Cu-H bonds compared to Au-H bonds which makes it possible for compound 2 to adopt the distorted tetrahedron structure.
|
-Secondary boranes have pi-bond donors that suppress reactivity in the absence of a catalyst, where metal catalysts increase boron electrophilicity and promote hydroboration.
-d10 metal centers engage in Z-type (2 electrons from metal to ligand) interactions with tricoordinate boron centers
|
[{"label":"RBK Item","value":"-d10 metal centers engage in Z-type (2 electrons from metal to ligand) interactions with tricoordinate boron centers "},{"label":"Title","value":"A neutral, acyclic, borataalkene-like ligand for group 11 metals: L- and Z-type ligands side by side"},{"label":"URL","value":"https://pubs.rsc.org/en/content/articlelanding/2022/cc/d2cc00199c"},{"label":"Date","value":"February 21, 2022"},{"label":"Justification (\"Paywalled\", \"OA\", \"Other (justify)\")","value":"Paywalled"},{"label":"RBK Item","value":"-Secondary boranes have pi-bond donors that suppress reactivity in the absence of a catalyst, to increase boron electrophilicity and promote hydroboration."},{"label":"Title","value":"Hydroboration of Terminal Alkynes Catalyzed by a Mn(I) Alkyl PCP Pincer Complex Following Two Diverging Pathways"},{"label":"URL","value":"https://pubs.acs.org/doi/10.1021/acscatal.4c03805"},{"label":"Date","value":"August 5, 2024"},{"label":"Justification (\"Paywalled\", \"OA\", \"Other (justify)\")","value":"Paywalled"}]
|
Chemistry
|
Material Chemistry
|
Free-Format Question
|
Solid-State NMR Provides Location-Specific Information on the Chemical Environment Inside MOF Pores
|
https://chemrxiv.org/engage/chemrxiv/article-details/68efb163dfd0d042d1a1ba9d
|
Oct 15, 2025
|
The researchers focus on the Zr₆ MOFs PCN-222 (PCN = porous coordination network) and PCN224. PCN-222 comprises 8-connected Zr₆-nodes and TCPP (5,10,15,20-tetrakis(4-carboxyphenyl)porphyrin) linkers, which are arranged in a csq net with 3.7 nm diameter mesopores and 1.3 nm micropores. PCN-224 is composed of the same nodes and linkers, but it only features a single type of pore within a 6-connected she topology. To probe the chemical environments present within the pores PCN-222 and PCN-224, they targeted a range of derivatives of the MOF linker in which a sensitive NMR nucleus, such as ¹H and ¹⁹F, extends into the pore space by different and known amounts. To that end, they prepared Rh(III)-porphyrin derivatives of the TCPP linker for which methyl, ethyl, or 4-fluoroaryl groups are bound to the axial position of Rh(III).
RhMe-1: PCN-222 prepared with Rh(III)-porphyrin methyl derivative of the TCPP
RhMe-2: PCN-224 prepared with Rh(III)-porphyrin methyl derivative of the TCPP
RhEt-1: PCN-222 prepared with Rh(III)-porphyrin ethyl derivative of the TCPP
RhEt-2: PCN-224 prepared with Rh(III)-porphyrin ethyl derivative of the TCPP
RhC₆H₄F-1: PCN-222 prepared with Rh(III)-porphyrin 4-fluoroaryl derivative of the TCPP
RhC₆H₄F-2: PCN-224 prepared with Rh(III)-porphyrin 4-fluoroaryl derivative of the TCPP
They analyse their phase purity and crystallinity using Powder X-ray diffraction (PXRD)
|
Phase purity and crystallinity using Powder X-ray diffraction (PXRD), on a STOE STADI P diffractometer operating in Debye Scherrer geometry with a Cu Kα radiation source and a primary germanium monochromator
|
Given RhMe-1, RhEt-1 and RhC₆H₄F-1, a Powder X-ray diffraction analysis was made. In which order (lowest to highest) do you expect the intensity obtained for these compounds?
|
RhC₆H₄F-1< RhEt-1 <RhMe-1
|
-The chemical environment inside a MOF pore determines which molecules can enter the pore, how strongly they bind, and which guests are preferred over others
-Both the structure of the empty framework pores, as well as the spatial positioning of guest molecules, can furthermore be resolved with exquisite precision by diffraction-based experimental techniques
|
[{"label":"RBK Item","value":"The chemical environment inside a MOF pore determines which molecules can enter the pore, how strongly they bind, and which guests are preferred over others"},{"label":"Title","value":"Metal-Organic Frameworks in Heterogeneous Catalysis: Recent Progress, New Trends, and Future Perspectives"},{"label":"URL","value":"https://pubs.acs.org/doi/10.1021/acs.chemrev.9b00685"},{"label":"Date","value":"March 30, 2020"},{"label":"Justification (\"Paywalled\", \"OA\", \"Other (justify)\")","value":"Paywalled"},{"label":"RBK Item","value":"Both the structure of the empty framework pores, as well as the spatial positioning of guest molecules, can furthermore be resolved with exquisite precision by diffraction-based experimental techniques\n"},{"label":"Title","value":"Study of Guest Molecules in Metal Organic Frameworks by Powder X-ray Diffraction: Analysis of Difference Envelope Density\n"},{"label":"URL","value":"https://www.researchgate.net/publication/278081910_Study_of_Guest_Molecules_in_Metal_Organic_Frameworks_by_Powder_X-ray_Diffraction_Analysis_of_Difference_Envelope_Density"},{"label":"Date","value":"November 2014"},{"label":"Justification (\"Paywalled\", \"OA\", \"Other (justify)\")","value":"Paywalled"}]
|
Chemistry
|
Organic Chemistry
|
Numerical Values
|
Thiourea-Functionalized Ligands for Tunable Solid-State Photoluminescence and Quenching-Based Metal Sensing
|
https://chemrxiv.org/engage/chemrxiv/article-details/68fb743c5dd091524f3fe77a
|
October 28, 2025
|
Researchers synthesised and characterised an aminopyrazole ligand, referred to as compound #2, as a precursor to thiourea-functionalized ligands for tunable solid-state photoluminescence and quenching-based metal sensing. For the synthesis of compound #2, 3-oxo-3-(pyridin-2-yl)propanenitrile (3.65 g, 25.5 mmol, 1.0 eq) was added to a single-neck 100 mL round-bottomed flask equipped with a condenser and oil bath, together with isopropanol (iPrOH, 40 mL) and 2-hydrazinopyridine (2.86 g, 26.2 mmol, 1.05 eq). Concentrated HCl (12 M, 3 drops) was added to the suspension, and the mixture was heated to reflux for 7 h until complete consumption of the α-cyano ketone was observed by TLC (SiO₂, 50% EtOAc/hexanes), at which point a clear red solution was obtained. After slight cooling, H₂O was added to the reaction mixture until a slight cloudiness persisted, and the mixture was cooled to 5 ºC to induce crystallisation. The resulting dark brown solid was collected by suction filtration and recrystallised from methanol to give light brown crystals of compound #2 (1.97 g, 8.3 mmol, 41% yield). The phase behaviour of compound #2 above room temperature was investigated by differential scanning calorimetry (DSC). DSC measurements were carried out on a TA Instruments DSC Q200 using repeated heating–cooling cycles between 20 ºC and 200 ºC at a scanning rate of 5 ºC/min, allowing determination of its melting temperature (Tm; ºC) and glass transition temperature (Tg; ºC).
|
- DSC measurements were carried out on a TA Instruments DSC Q200 using repeated heating–cooling cycles between 20 ºC and 200 ºC at a scanning rate of 5 ºC/min, allowing determination of its melting temperature (Tm; ºC) and glass transition temperature (Tg; ºC).
|
Researchers synthesized an aminopyrazole ligand, referred to as compound #2, which serves as a precursor to thiourea-functionalized ligands. The phase behavior of compound #2 above room temperature was investigated by differential scanning calorimetry (DSC), using repeated heating–cooling cycles to determine its glass transition temperature (Tg; ºC). Which is the expected Tg (ºC) value obtained for compound #2?
|
Glass transition temperature (Tg) = 56 ºC -> [50 - 62 ºC]
|
- Predicting how molecules will pack, and how that packing will influence emergent properties, is still limited by the availability of well-defined, systematically tunable ligand frameworks.
- Intermolecular interactions often compete in unpredictable hierarchies, for example, a large number of weaker forces (dipole-dipole, van der Waals, 𝜋 − 𝜋) may compete with a smaller number of stronger forces (hydrogen and halogen bonds) to orient the molecules in unanticipated spatial arrangements (self-assembly) to produce ordered structures; or where multiple stronger forces are present, these may compete with each other to produce different ordered structures (ie. polymorphs).
- Thioureas offer promising design features as they also incorporate amine-based hydrogen bond donors and as such, have been widely used in anion sensing and crystal engineering
|
[{"label":"RBK Item","value":"- Predicting how molecules will pack, and how that packing will influence emergent properties, is still limited by the availability of well-defined, systematically tunable ligand frameworks."},{"label":"Title","value":"Supramolecular Coordination: Self-Assembly of Finite Two- and Three-Dimensional Ensembles"},{"label":"URL","value":"https://pubs.acs.org/doi/full/10.1021/cr200077m"},{"label":"Date","value":"August 24, 2011"},{"label":"Justification (\"Paywalled\", \"OA\", \"Other (justify)\")","value":"Paywalled"},{"label":"RBK Item","value":"Intermolecular interactions often compete in unpredictable hierarchies, for example, a large number of weaker forces (dipole-dipole, van der Waals, 𝜋 − 𝜋) may compete with a smaller number of stronger forces (hydrogen and halogen bonds) to orient the molecules in unanticipated spatial arrangements (self-assembly) to produce ordered structures; or where multiple stronger forces are present, these may compete with each other to produce different ordered structures (ie. polymorphs)."},{"label":"Title","value":"Competitive Hydrogen Bonding and Unprecedented Polymorphism in Selected Chiral Phosphorylated Thioureas"},{"label":"URL","value":"https://pubs.acs.org/doi/abs/10.1021/acs.cgd.1c00758"},{"label":"Date","value":"August 17, 2021"},{"label":"Justification (\"Paywalled\", \"OA\", \"Other (justify)\")","value":"Paywalled"},{"label":"RBK Item","value":"- Thioureas offer promising design features as they also incorporate amine-based hydrogen bond donors and as such, have been widely used in anion sensing and crystal engineering"},{"label":"Title","value":"Thiourea-Based Receptors for Anion Recognition and Signaling"},{"label":"URL","value":"https://pubs.acs.org/doi/full/10.1021/acsomega.3c06861"},{"label":"Date","value":"January 17, 2024"},{"label":"Justification (\"Paywalled\", \"OA\", \"Other (justify)\")","value":"OA"}]
|
Chemistry
|
Physical Chemistry, Analytical Chemistry
|
Numerical Values
|
Time-resolved study of in-situ generated protein subcomplexes by tandem-trapped ion mobility spectrometry
|
https://chemrxiv.org/engage/chemrxiv/article-details/68fb73583e6156d3bec22a9a
|
October 28, 2025
|
Researchers investigated the stability of in-situ generated streptavidin subcomplexes using a tandem-trapped ion mobility spectrometer (Tandem-TIMS). Streptavidin tetramers (15+ charge state) were separated by ion mobility in the TIMS-1 cell under gentle conditions to preserve intact structures.
Streptavidin samples (2.5 µM) were analyzed by nanoelectrospray, introducing desolvation gas at 2.5 L min⁻¹ and applying a voltage of 3500 V. The TIMS instrument operated at temperatures of 323 K and controlled pressures between 3.1 and 0.4 mbar, using radiofrequency potentials of 566 and 443 kHz. Mobility separation was achieved using linear voltage ramps in the TIMS-1 and TIMS-2 analyzers, acquiring the spectra in positive ion mode.
Tetramers of the selected charge state were mobility-selected and exposed to a high electric field between TIMS-1 and TIMS-2, inducing fragmentation into monomers (3+), dimers (7+), and trimers (7+ and 8+) via collision-induced dissociation (CID). The resulting subcomplexes were transferred into TIMS-2 and trapped for different times, after which ion mobility measurements were used to monitor time-dependent structural changes. This assessment was conducted to monitor time-dependent structural changes in the in-situ generated streptavidin subcomplexes. Cross-section distributions over time spectra were obtained.
|
- Time-resolved ion mobility spectrometry measurements of in situ generated
streptavidin subcomplexes in Tandem-TIMS, to obtain the structural stability monitored over time (cross-section distributions).
|
Using Tandem-TIMS, streptavidin tetramers (native-like 15+ charge state) were mobility-selected in TIMS-1 and fragmented into monomers (3+), dimers (7+), and trimers (7+ and 8+) via collision-induced dissociation (CID) at the interface between TIMS-1 and TIMS-2. The resulting subcomplexes were trapped in TIMS-2 for varying durations. Based on these time-resolved ion mobility measurements, for how many seconds did the collision cross-section distributions of the monomers remain unchanged, indicating structural stability in the gas phase?
|
Time: [9.8-10.8] s
±5% Time Durations fallback applied
|
- Tandem-ion mobility spectrometry (tandem-IMS) enables novel experimental workflows by allowing ions to be mobility-selected, activated, and reseparated.
- Tandem-TIMS features two sequential trapped ion mobility spectrometry cells, each capable of performing mobility separation and gas phase trapping for up to 20
seconds. The interface between TIMS-1 and TIMS-2 cells consists of two ion apertures that facilitate the selection of ions with specific mobilities.
- Streptavidin forms native-like tetramers that can be mobility-selected in Tandem-TIMS.
|
[{"label":"RBK Item","value":"Tandem-ion mobility spectrometry (tandem-IMS) enables novel experimental workflows by allowing ions to be mobility-selected, activated, and reseparated "},{"label":"Title","value":"An IMS−IMS Analogue of MS−MS"},{"label":"URL","value":"https://pubs.acs.org/doi/10.1021/ac051060w"},{"label":"Date","value":"May 11, 2006"},{"label":"Justification (\"Paywalled\", \"OA\", \"Other (justify)\")","value":"Paywalled"},{"label":"RBK Item","value":"Tandem-TIMS features two sequential trapped ion mobility spectrometry cells, each capable of performing mobility separation and gas phase trapping for up to 20\nseconds. The interface between TIMS-1 and TIMS-2 cells consists of two ion apertures that facilitate the selection of ions with specific mobilities."},{"label":"Title","value":"Tandem-trapped ion mobility spectrometry/mass spectrometry coupled with ultraviolet photodissociation"},{"label":"URL","value":"https://analyticalsciencejournals.onlinelibrary.wiley.com/doi/10.1002/rcm.9192"},{"label":"Date","value":"September 8, 2021"},{"label":"Justification (\"Paywalled\", \"OA\", \"Other (justify)\")","value":"Paywalled"},{"label":"RBK Item","value":"Streptavidin forms native-like tetramers that can be mobility-selected in Tandem-TIMS."},{"label":"Title","value":"Elucidating Structures of Protein Complexes by Collision-Induced Dissociation at Elevated Gas Pressures"},{"label":"URL","value":"https://pubs.acs.org/doi/10.1021/jasms.3c00191"},{"label":"Date","value":"September 20, 2023"},{"label":"Justification (\"Paywalled\", \"OA\", \"Other (justify)\")","value":"Paywalled"}]
|
Chemistry
|
Nanoparticles
|
MCQ
|
Solvent-Dependent Stabilization of Gold Nanoparticles: A Comparative Study on Polymers and the Influence of Their Molecular Weight in Water and Ethanol
|
https://www.mdpi.com/2624-8549/7/5/159
|
Oct 01, 2025
|
The researchers performed a systematic comparison of different polymers, synthesis methods and solvents in regards to Gold nanoparticles (AuNPs). The AuNPs were synthesized using the ligand exchange reaction/post-synthetic addition reaction (PAR) and the one-pot synthesis with the polymers poly(vinyl alcohol) (PVA), poly(ethylene glycol) (PEG), poly(vinylpyrrolidone) (PVP) and poly(acrylic acid) (PAA), each with different molar weight averages.
For the PAR, in a 500 mL Erlenmeyer flask with a glass stopper, a total of 20 mg (52.9 µmol) of KAuCl₄ was dispersed in 200 mL ultrapure water and heated to 100 °C. 90 mg (350 µmol) of NaCit was then added and the solution was heated to 100 °C for 15 min. During this time, the solution changed color from light yellow to dark red. Finally, the solution was cooled to room temperature, 4.3 µmol of polymer was added and stirring for 12 h. DLS and UV-Vis measurements were taken directly after the 12 h. The DLS measurements were taken without dilution, and for the UV-Vis measurements, the solution was diluted with water in a ratio of 50:50.
For the One-Pot Synthesis, in a 500 mL round bottom flask, the amount of 20 mg (52.9 µmol) of KAuCl₄ and 4.3 µmol of polymer were dissolved in 200 mL of ultrapure water and the solution was heated to 90 °C under stirring.. Then, 90 mg (350 µmol) of NaCit was added and the solution continued to be stirred for 30 min. The color changed from light yellow to dark red. The DLS and UV-Vis measurements were taken directly after cooling to room temperature.
|
• TEM analysis of the AuNPs made by PAR method and by one-pot synthesis in water, to determine their size. Graphical analysis of the TEM-derived AuNP core size and their standard deviation of the conjugates in water: (a) AuNP@PVA, (b) AuNP@PEG, (c) AuNP@PVP and (d) AuNP@PAA in water.
• Hydrodynamic diameters and the polydispersity index using DLS. Graphical analysis of all the DLS results in water of (a) AuNP@PVA, (b) AuNP@PEG, (c) AuNP@PVP and (d) AuNP@PAA.
• Comparative analysis of the TEM size from PAR in water and ethanol of (a) AuNP@PVA, (b) AuNP@PEG, (c) AuNP@PVPand(d) AuNP@PAA.
• Comparative overview of the hydrodynamic diameter from DLS from PAR in water and ethanol of (a) AuNP@PVA, (b) AuNP@PEG, (c) AuNP@PVP and (d) AuNP@PAA.
|
The colloidal stability of Gold Nanoparticles (AuNPs) depends on the nature of the polymer used in their synthesis. Based on this research work, which of the following polymers shows the best stability in water and after transfer to ethanol, irrespective of whether they are synthesized by the post-synthetic addition reaction method (PAR) or the one-pot method?
(a) AuNP@PVA
(b) AuNP@PEG
(c) AuNP@PVP
(d) AuNP@PAA
|
(a) AuNP@PVA
|
• The targeted control of size, shape, monodispersity and surface functionalization of AuNPs plays a central role in their successful use in nanomedicine.
• Polymers are used for AuNP stabilization.
• The molecular weight of the polymers plays a decisive role, as it significantly influences the density, thickness, and stability of the polymer shell and thus directly determines the stability of the AuNPs.
• Various synthesis methods are often used to produce stabilized AuNPs.
• A knowledge and comparison of different polymer-based stabilization and optimized synthesis methods are crucial to prepare stable AuNPs and to avoid unwanted agglomeration with loss of functionality.
• The molecular weight of individual polymers can influence on the stability of AuNPs.
|
[{"label":"RBK Item","value":"The targeted control of size, shape, monodispersity and surface functionalization of AuNPs plays a central role in their successful use in nanomedicine."},{"label":"Title","value":"Nanoparticles in microelectronics advancements and biomedical applications."},{"label":"URL","value":"https://doi.org/10.1016/j.mseb.2024.117191"},{"label":"Date","value":"March, 2024"},{"label":"Justification (\"Paywalled\", \"OA\", \"Other (justify)\")","value":"Paywalled"},{"label":"RBK Item","value":"Polymers are used for AuNP stabilization."},{"label":"Title","value":"The Effects of Polymer Coating of Gold Nanoparticles on Oxidative Stress and DNA Damage."},{"label":"URL","value":"https://doi.org/10.1177/1091581820927646"},{"label":"Date","value":"June, 2020"},{"label":"Justification (\"Paywalled\", \"OA\", \"Other (justify)\")","value":"OA"},{"label":"RBK Item","value":"The molecular weight of the polymers also plays a decisive role, as it significantly influences the density, thickness, and stability of the polymer shell and thus directly determines the stability of the AuNPs."},{"label":"Title","value":"Highly Stable Au Nanoparticles with Double Hydrophilic Block Copolymer Templates: Correlation between Structure and Stability"},{"label":"URL","value":"https://doi.org/10.1039/c7py00773f"},{"label":"Date","value":"August, 2017"},{"label":"Justification (\"Paywalled\", \"OA\", \"Other (justify)\")","value":"Paywalled"},{"label":"RBK Item","value":"Various synthesis methods are often used to produce stabilized AuNPs."},{"label":"Title","value":"Direct Bottom-Up In Situ Growth: A Paradigm Shift for Studies in Wet-Chemical Synthesis of Gold Nanoparticles."},{"label":"URL","value":"https://doi.org/10.1021/acs.chemrev.2c00914"},{"label":"Date","value":"June, 2023"},{"label":"Justification (\"Paywalled\", \"OA\", \"Other (justify)\")","value":"OA"},{"label":"RBK Item","value":"A knowledge and comparison of different polymer-based stabilization and optimized synthesis methods are crucial to prepare stable AuNPs and to avoid unwanted agglomeration with loss of functionality"},{"label":"Title","value":"Preparation, aging and temperature stability of PEGylated gold nanoparticles. "},{"label":"URL","value":"https://doi.org/10.1016/j.colsurfa.2017.04.005"},{"label":"Date","value":"June, 2017"},{"label":"Justification (\"Paywalled\", \"OA\", \"Other (justify)\")","value":"Paywalled"},{"label":"RBK Item","value":"The molecular weight of individual polymers can influence on the stability of AuNPs."},{"label":"Title","value":"Enhanced dispersion stability of gold nanoparticles by the physisorption of cyclic poly(ethylene glycol)"},{"label":"URL","value":"https://doi.org/10.1038/s41467-020-19947-8"},{"label":"Date","value":"November, 2020"},{"label":"Justification (\"Paywalled\", \"OA\", \"Other (justify)\")","value":"OA"}]
|
Chemistry
|
Organic chemistry, metabolic/biocompatible catalysis
|
MCQ
|
A biocompatible Lossen rearrangement in Escherichia coli
|
https://www.nature.com/articles/s41557-025-01845-5
|
June 23, 2025
|
A one-pot two-step procedure was optimized to enhance the synthetic utility of paracetamol synthesis from polyethylene terephthalate (0.5 mM), which is incubated at 50 °C in aqueous phosphate buffer (200 mM, 50 °C, pH 8.0), followed by the addition of induced E. coli BW25113ΔpabB_p354 and E. coli BW25113ΔpabB_p350 whole cells expressing panat and abh60, respectively (1:200, 37 °C, OD600 of 12.5–25). L-arabinose was used for induction by default. Under these conditions, the quantitative yield of paracetamol was observed from para-aminobenzoate (PABA).
|
-Final paracetamol yield (%) at the end of the one-pot sequence quantified by ¹H NMR or HPLC versus an internal standard.
|
Using a one-pot two-step procedure, a sponsor requires enabling a reduction in the ratio of panat and abh60 expressing strains to 1:100. What modification can be made to further produce a higher final yield of paracetamol?
A) Increase L-arabinose during the protein-expression phase, leave all other parameters unchanged.
B) Decrease L-arabinose during the protein-expression phase, leaving PET loading, buffer identity/strength/pH, and analytics unchanged.
C) Decrease L-arabinose during the protein-expression, leave all other parameters unchanged except durations.
D) Keep L-arabinose and shorten the Lossen stage, all else unchanged.
|
B) Decrease L-arabinose during the protein-expression phase, leaving PET loading, buffer identity/strength/pH, and analytics unchanged.
|
-Biocompatible reactions are non-enzymatic chemical transformations that can be interfaced with cellular metabolism.
-The field of synthetic organic chemistry can access reactivity not observed in nature, and integration of these abiotic reactions within living systems offers a solution to the sustainable synthesis of many industrial chemicals from renewable feedstocks.
-The Lossen rearrangement is characterized by the thermal- or metal-catalysed expulsion of a carboxylate from a bis-acylated hydroxylamine substrate. Overall, the reaction generates primary amines from carboxylate substrates with an accompanying one-carbon contraction, contrasting with the enzymatic chemistry enabled by ammonia lyases and aminotransferases
|
[{"label":"RBK Item","value":"Biocompatible reactions are non-enzymatic chemical transformations that can be interfaced with cellular metabolism."},{"label":"Title","value":"Using non-enzymatic chemistry to influence microbial metabolism."},{"label":"URL","value":"https://www.sciencedirect.com/science/article/abs/pii/S136759311400194X"},{"label":"Date","value":"January 8, 2015"},{"label":"Justification (\"Paywalled\", \"OA\", \"Other (justify)\")","value":"Paywalled"},{"label":"RBK Item","value":"The field of synthetic organic chemistry can access reactivity not observed in nature, and integration of these abiotic reactions within living systems offers a solution to the sustainable synthesis of many industrial chemicals from renewable feedstocks.\n"},{"label":"Title","value":"Opportunities for merging chemical and biological synthesis"},{"label":"URL","value":"https://pubmed.ncbi.nlm.nih.gov/24747284/"},{"label":"Date","value":"April 14, 2018"},{"label":"Justification (\"Paywalled\", \"OA\", \"Other (justify)\")","value":"OA"},{"label":"RBK Item","value":"The Lossen rearrangement is characterized by the thermal- or metal-catalysed expulsion of a carboxylate from a bis-acylated hydroxylamine substrate. Overall, the reaction generates primary amines from carboxylate substrates with an accompanying one-carbon contraction, contrasting with the enzymatic chemistry enabled by ammonia lyases and aminotransferases."},{"label":"Title","value":"Ueber Benzoylderivate des Hydroxylamins"},{"label":"URL","value":"https://chemistry-europe.onlinelibrary.wiley.com/doi/10.1002/jlac.18721610219"},{"label":"Date","value":"1872"},{"label":"Justification (\"Paywalled\", \"OA\", \"Other (justify)\")","value":"OA"}]
|
Chemistry
|
Materials Science / Optoelectronic Devices
|
Numerical Values
|
Improved operating voltage in InGaN-capped AlGaN-based DUV LEDs on bulk AlN substrates
|
https://arxiv.org/abs/2510.24892
|
Oct 28, 2025
|
Epitaxial growth: All samples grown by nitrogen plasma-assisted molecular beam epitaxy (MBE) on +c-plane single-crystal bulk AlN substrates.
Contact metallurgy & anneals: p-contacts — Ni/Au (15/20 nm), rapid thermal anneal (RTA) at 450 °C for 30 s in O₂ ambient. n-contacts — V/Al/Ni/Au (20/80/40/100 nm) deposited by e-beam evaporation; RTA for n-contacts performed at varied temperatures (600 °C, 700 °C, 800 °C) for 30 s in N₂ ambient. In integrated LED processing, p-contacts are deposited after the n-contact anneal.
SiO₂ capping process: For the SiO₂-protected experiments, a 50 nm SiO₂ cap was deposited by plasma-enhanced atomic layer deposition (PE-ALD) prior to high-temperature n-contact anneal to protect the p-InGaN surface during the n-contact anneal.
Device fabrication: Mesa formation by ICP-RIE etching (~50 nm into n-Al₀.₇₆Ga₀.₂₄N), contact deposition as above, dicing into 1×1 cm² samples for comparative studies. Diode devices fabricated and characterized; LED emission at ~268 nm reported.
|
Diode J–V (current density vs voltage) characteristics and differential ON-resistance (R_on): measured for LEDs fabricated with and without SiO₂ cap; R_on extracted at a specified current density (400 A/cm²). Comparison dimension: SiO₂-capped LED vs uncapped LED (same wafer).
|
Two DUV LED samples were fabricated from the same epitaxial wafer. One sample used the SiO₂ capping technique and the other did not. Diodes were tested randomly from
each sample. At room temperature, the current density vs. voltage was analyzed of the best-performing diode from each group (selected based on the lowest ON-resistance at 10 V). At 400 A/cm², what is the approximate difference (in voltage) obtained from the SiO₂-capped diode compared to the uncapped diode?
|
3.8 V → [3.42 V - 4.2 V]
|
-Dielectric (SiO2, SiNx) or epitaxial cap layers (GaN, AlN) are used to protect the device before contact deposition
|
[{"label":"RBK Item","value":"Molecular beam epitaxy (MBE) growth of III-nitride heterostructures and typical stack used for DUV LEDs"},{"label":"Title","value":"Demonstration of AlGaN-on-AlN pn diodes with dopant-free distributed polarization doping"},{"label":"URL","value":"https://www.researchgate.net/publication/378506332_Demonstration_of_AlGaN-on-AlN_p-n_Diodes_With_Dopant-Free_Distributed_Polarization_Doping"},{"label":"Date","value":"February 26, 2024"},{"label":"Justification (\"Paywalled\", \"OA\", \"Other (justify)\")","value":"OA"}]
|
Chemistry
|
Analytical Chemistry / Electrochemistry
|
Numerical Values
|
Determination of Caffeine in Energy Drinks Using a Composite Modified Sensor Based on Magnetic Nanoparticles
|
https://www.mdpi.com/1420-3049/30/10/2219
|
May 20, 2025
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Researchers developed a new voltammetric sensor for detecting and measuring caffeine (CAF) levels in solution. For that purpose, 0.5 mg of Fe3O4 nanoparticles (nanopowder, 50–100 nm particle size, Sigma-Aldrich, Germany) were mixed with 100 µL of 3% (w/v) nafion (etrafluoroethylene-perfluoro-3,6-dioxa-4-methyl-7-octenesulfonic acid copolymer) in ethanol and placed in an ultrasonic bath for 2 h, to render a nanocomposite, which was further employed to coat a boron-doped diamond electrode (BDDE). The BDDE was commercially available (Windsor Scientific Ltd., Slough, Berkshire, UK) and acquired in an inert polytetrafluoroethylene (PTFE, Teflon) body with an inner diameter of 3 mm (D-086-SA, boron doping level of 1000 ppm, electrical resistivity of 0.075 Wm). The surface of the BDDE was polished using 0.3 µm alumina slurry on a Buehler polishing pad (Lake Bluff, IL, USA) before applying the nanocomposite layer. After polishing, 0.5 µL of nanocomposite was applied to the BDDE surface and after 5 min at room temperature, the electrode was submerged into a solution of 0.1 M H2SO4, 6 µM Bi(III), and 0.1 µM CAF. Simultaneous bismuth film deposition and CAF accumulation in the electrode occured at a potential of −0.95 V (Edep.Bi+acc.CAF) for 60 s (tdep.Bi+acc.CAF) under stirring. Voltammetric studies were performed with the as prepared electrode (BDDE/Nafion@Fe3O4/BiF), using an electrochemical analyzer µAutolab (Eco Chemie, Utrecht, The Netherlands), an electrochemical cell with a silver chloride electrode (3 M KCl, reference) and a Pt wire (auxiliary electrode). Differential-pulse adsorptive stripping voltammograms (DPAdSVs) were registered in the range of 0.25 to 1.85 V with the amplitude (ΔEA) of 75 mV, the scan rate (υ) of 175 mV/s, and the modulation time (tm) of 4 ms. The background was subtracted from each measurement.
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- Current (I, µA) measured with the BDDE/Nafion@Fe3O4/BiF electrode at 0.1 µM caffeine concentration, from 0.25 to 1.85 V, at amplitude (ΔEA) of 75 mV, scan rate (υ) of 175 mV/s, and modulation time (tm) of 4 ms (Differential-pulse adsorptive stripping voltammetry).
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Researchers developed a new voltammetric sensor for detecting and measuring caffeine (CAF) levels in solution by depositing 0.5 µL of nanocomposite (0.5 mg of Fe3O4 nanopowder [50–100 nm particle size] in 100 µL of 3% (w/v) nafion [etrafluoroethylene-perfluoro-3,6-dioxa-4-methyl-7-octenesulfonic acid copolymer] in ethanol) onto the polished surface of a boron-doped diamond electrode ([BDDE] inner diameter: 3 mm; boron doping: 1000 ppm; electrical resistivity: 0.075 Wm). After nanocomposite drying, the as modified BDDE was submerged in 0.1 M H2SO4, 6 µM Bi(III), and 0.1 µM CAF for simultaneous bismuth film deposition and CAF accumulation at −0.95 V for 60 s under stirring. Differential-pulse adsorptive stripping voltammograms (DPAdSVs) were registered with the as-prepared electrode (BDDE/Nafion@Fe3O4/BiF) using an electrochemical analyzer equipped with an electrochemical cell with a silver chloride electrode (3 M KCl, reference) and a Pt wire (auxiliary electrode), in the range of 0.25 to 1.85 V with the amplitude (ΔEA) of 75 mV, the scan rate (υ) of 175 mV/s, and the modulation time (tm) of 4 ms. The background was subtracted from each measurement. What is the expected current value (I, µA) given by the BDDE/Nafion@Fe3O4/BiF electrode, at the voltage (V) value of 1.4V?
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Current (I) for 0.1 µM caffeine measured with BDDE/Nafion@Fe3O4/BiF electrode at 1.4V, amplitude (ΔEA) of 75 mV, scan rate (υ) of 175 mV/s, and modulation time (tm) of 4 ms = 2.25 - 2.75 µA. Note: no CI/SE/SD reported → fallback ±10% applied over the value of 2.5 µA.
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- Voltammetry is a method that can be employed to determine caffeine concentrations in solution.
- Nafion (etrafluoroethylene-perfluoro-3,6-dioxa-4-methyl-7-octenesulfonic acid copolymer) is a cation exchanger that is used to coat the surface of electrodes.
- Fe3O4 nanoparticles are magnetic nanoparticles that promote a very fast electron transfer between the sensor and the active site of the redox reaction.
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[{"label":"RBK Item","value":"- Voltammetry is a method that can be employed to determine caffeine concentrations in solution."},{"label":"Title","value":"Bismuth particles Nafion covered boron-doped diamond electrode for simultaneous and individual voltammetric assays of paracetamol and caffeine"},{"label":"URL","value":"https://doi.org/10.1016/j.snb.2016.05.087"},{"label":"Date","value":"May 17, 2016"},{"label":"Justification (\"Paywalled\", \"OA\", \"Other (justify)\")","value":"Paywalled version is the one cited by the paper"},{"label":"RBK Item","value":"- Nafion (etrafluoroethylene-perfluoro-3,6-dioxa-4-methyl-7-octenesulfonic acid copolymer) is a cation exchanger that is used to coat the surface of electrodes.\n"},{"label":"URL","value":"Simultaneous Determination of Caffeine and Pyridoxine in Energy Drinks using Differential Pulse Voltammetry at Glassy Carbon Electrode Modified with Nafion®"},{"label":"URL","value":"https://analyticalsciencejournals.onlinelibrary.wiley.com/doi/10.1002/elan.201800646"},{"label":"Date","value":"May 22, 2019"},{"label":"Justification (\"Paywalled\", \"OA\", \"Other (justify)\")","value":"Paywalled version is the one cited by the paper"},{"label":"RBK Item","value":"- Fe3O4 nanoparticles are magnetic nanoparticles that promote a very fast electron transfer between the sensor and the active site of the redox reaction."},{"label":"Title","value":"DNA Modified Fe3O4@Au Magnetic Nanoparticles as Selective Probes for Simultaneous Detection of Heavy Metal Ions"},{"label":"URL","value":"https://pubs.acs.org/doi/10.1021/acsami.6b14247"},{"label":"Date","value":"January 12, 2017"},{"label":"Justification (\"Paywalled\", \"OA\", \"Other (justify)\")","value":"Paywalled version is the one cited by the paper"}]
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Chemistry
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Analytical Chemistry
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MCQ
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Cross-Platform Ion Mobility-Mass Spectrometry of Cationized Imidacloprid and Chlorpyrifos
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https://chemrxiv.org/engage/chemrxiv/article-details/68f051915dd091524fb24491
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Oct 15, 2025
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Researchers investigated how cationization with different metal ions affects the gas-phase structure and ion mobility of two pesticide molecules, imidacloprid and chlorpyrifos. Analytical standards of both compounds were dissolved in methanol/water (1:1, v/v) at a final concentration of approximately 10 µM. To generate protonated, sodiated, and potassiated species, 100 µM NaCl or KCl was added to form [Imi+cation]⁺ and [CPF+cation]⁺ (where cation = H⁺, Na⁺, or K⁺) under positive-mode electrospray ionization (ESI) conditions. Samples were analyzed using four ion mobility–mass spectrometry (IM–MS) platforms: drift tube (DTIM), traveling wave (TWIM), trapped ion (TIMS), and cyclic ion mobility (cIM), with nitrogen as the drift gas to determine the experimental collision cross sections (CCS) for each adduct type.
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- Collision cross sections (CCS) of protonated, sodiated, and potassiated imidacloprid and chlorpyrifos measured by drift tube (DTIM), traveling wave (TWIM), trapped ion (TIMS), and cyclic ion mobility (cIM) mass spectrometry in nitrogen gas.
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Researchers investigated how cationization with different metal ions affects the gas-phase structure and ion mobility of imidacloprid and chlorpyrifos using four ion mobility mass spectrometry (IM–MS) platforms: drift tube (DTIM), traveling wave (TWIM), trapped ion (TIMS), and cyclic ion mobility (cIM). Protonated, sodiated, and potassiated adducts were generated under positive-mode electrospray ionization (ESI) to measure their experimental collision cross sections (CCS) in nitrogen. Which of the following outcomes is most likely? (Mark all correct)
A. Both imidacloprid and chlorpyrifos show increasing CCS values from protonated to sodiated to potassiated forms.
B. Chlorpyrifos exhibits a larger CCS increase than imidacloprid upon cationization with Na⁺ and K⁺.
C. Significant differences are observed in CCS values among the four IM–MS platforms.
D. Sodiated [Imi+Na]+ and [CPF+Na]+ species are the most abundant in the mass spectra compared to their potassiated analogues
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A. Both imidacloprid and chlorpyrifos show increasing CCS values from protonated to sodiated to potassiated forms.
B. Chlorpyrifos exhibits a larger CCS increase than imidacloprid upon cationization with Na⁺ and K⁺.
D. Sodiated [Imi+Na]+ and [CPF+Na]+ species are the most abundant in the mass spectra compared to their potassiated analogues.
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- Imidacloprid: (1-(6-chloro-3-pyridylmethyl)-N-nitroimidazolidin-2-ylideneamine, an organochlorine neonicotinoid is almost harmless to humans. However, it can adversely impact beneficial pollinators or have less obvious side effects.
- Chlorpyrifos: (O,O-diethyl O-(3,5,6-trichloro-2-pyridyl) phosphorothioate) is an organothiophosphate capable of disrupting an insect’s nervous system, resulting in paralysis and (eventually) death.
- Ion mobility–mass spectrometry (IM–MS): can potentially separate any isomers based on their mobility.
-Collision Cross Section (CCS): could help act as a molecular identifier combined with mass to charge ratio (m/z).
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[{"label":"RBK Item","value":"Chlorpyrifos: (O,O-diethyl O-(3,5,6-trichloro-2-pyridyl) phosphorothioate is an organothiophosphate capable of disrupting an insect’s nervous system, resulting in paralysis and (eventually) death."},{"label":"Title","value":"A comprehensive review on chlorpyrifos toxicity with special reference to endocrine disruption: Evidence of mechanisms, exposures and mitigation strategies"},{"label":"URL","value":"https://www.sciencedirect.com/science/article/abs/pii/S0048969720361787"},{"label":"Date","value":"February 10, 2021"},{"label":"Justification (\"Paywalled\", \"OA\", \"Other (justify)\")","value":"Paywalled"}]
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Chemistry
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Environmental Chemistry / Catalysis
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Numerical Values
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Catalytic Ozonation of Diclofenac Using CuO/Al2O3- and MnO2/Al2O3-Supported Catalysts
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https://www.mdpi.com/2624-8549/7/4/107
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June 25, 2025
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Researchers evaluated the catalytic ozonation of diclofenac (DFC) using a CuO/Al₂O₃-supported catalyst. The catalyst was prepared by incipient wetness impregnation. Al2O3 was dried at 110 ºC for 2 h in a drying oven. Dry Al2O3 powder was weighed, denoting the mass as m1. The carrier was submerged with distilled water by dropwise addition to a beaker, and the mass denoted as m2. The following equation was used to calculate the saturated water absorption rate: Water absorption of carrier = [(m2 − m1)/m1] × 100%. The quasi-loading rate of CuO was 10%. The water absorption rate of Al2O3 and the quasi-loading rate of CuO were employed to calculate the Cu(NO3)2·3H2O solution requirements for the impregnation method. The determined mass of Al2O3 was added to the corresponding volume of Cu(NO3)2·3H2O and stirred. After standing for 24 h, the solution was dried at 110 ºC for 10 h to obtain a bulk solid, which was further calcined at 450 ºC for 5 h and ground into powder.
Catalytic ozonation studies were carried out in batch mode at ambient temperature using a glass flat-bottom flask. A 100 mg/L DFC water solution (pH: 7.35) containing 1.0 g/L catalyst (Catalyst active component loading: 10%) was treated with O3 at a constant flow-rate of 0.2 m^3/h under magnetic stirring. Samples were collected from the reactor every 10 min up to a total reaction time of 60 min. Samples were filtered immediately after collection, and the content of DFC in supernatants was detected by HPLC. A chromatographic column (5 μm, 4.6 mm × 250 mm) was used with a mobile phase of methanol-4% glacial acetic acid solution (70:30), at a flow rate of 1.0 mL/min, 35 ºC, and a detection wavelength of 276 nm. The DCF removal rate was calculated as η = [(Co − Ct/Co] × 100%; where η represents the removal rate of DCF at time t (%); Co represents the initial concentration of diclofenac in the reaction solution (mg/L), and Ct represents the concentration of diclofenac in the reaction solution at time t (mg/L).
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- Diclofenac removal rate (%) after 10, 20, 30, 40, 50 and 60 minutes of CuO/Al₂O₃-supported catalysis at pH 7.35 and 1.0 g/L catalyst concentration (HPLC).
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Researchers evaluated the catalytic ozonation of diclofenac (DFC) using a CuO/Al₂O₃-supported catalyst. The catalyst was prepared by incipient wetness impregnation, with a quasi-loading rate of CuO of 10%. Catalytic ozonation studies were carried out in batch mode at ambient temperature with a 100 mg/L DFC water solution (pH: 7.35) containing 1.0 g/L catalyst and a O3 constant flow-rate of 0.2 m^3/h under magnetic stirring. Samples were collected from the reactor every 10 min up to a total reaction time of 60 min, the content of DFC in the samples was detected by HPLC, and the DCF removal rate (%) was calculated. What is the expected DFC removal rate (%) after 60 minutes of reaction time?
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Diclofecnac removal rate (t = 60 min) = 68.99 - 78.99 %. Note: No CI/SE/SD reported → fallback ± 5 percent points applied over the value of 73.99 %.
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- Diclofenac (DCF) is a widely used non-steroidal anti-inflammatory drug (NSAID), frequently detected in surface water, groundwater, and drinking water.
- Ozonation is an advanced oxidation process employed for the degradation of refractory organic contaminants.
- Al2O3 is a widely used catalyst support with high surface area, thermal stability, and inherent Lewis acidity.
- The incipient wetness impregnation method is a catalyst preparation method that relies on saturating a catalyst support (e.g. Al2O3) with a catalyst-containing solution (e.g. Cu(NO3)2) at proportions determined to reach a given catalyst loading rate (i.e. 10%).
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[{"label":"RBK Item","value":"- Diclofenac (DCF) is a widely used non-steroidal anti-inflammatory drug (NSAID), frequently detected in surface water, groundwater, and drinking water."},{"label":"Title","value":"Improving management and antimicrobial stewardship for bacterial and fungal infections in hospitalized patients with COVID-19"},{"label":"URL","value":" https://journals.sagepub.com/doi/10.1177/20499361221095732\n"},{"label":"Date","value":"May 14, 2022"},{"label":"Justification (\"Paywalled\", \"OA\", \"Other (justify)\")","value":"OA"},{"label":"RBK Item","value":"- Ozonation is an advanced oxidation process employed for the degradation of refractory organic contaminants."},{"label":"Title","value":"Degradation of prometryn in Ruditapes philippinarum using ozonation: Influencing factors, degradation mechanism, pathway and toxicity assessment"},{"label":"URL","value":"https://www.sciencedirect.com/science/article/abs/pii/S0045653520302113?via%3Dihub\n"},{"label":"Date","value":"January 28, 2020"},{"label":"Justification (\"Paywalled\", \"OA\", \"Other (justify)\")","value":"Paywalled version is the RBK item cited by this paper"}]
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Chemistry
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Catalysis
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Free-Format Question
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Polyester (PET) Degradation in Mild-Alkaline Solutions Assisted by Ultrasonication and UV-Activated Metal Oxides
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https://chemrxiv.org/engage/chemrxiv/article-details/68f676603e6156d3be019570
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October 23, 2025
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In this experiment, researchers investigated the effect of five metal oxide catalysts: zinc oxide (ZnO), zinc ferrite (ZnFe₂O₄), yttrium oxide (Y₂O₃), iron(III) oxide (Fe₂O₃), and strontium oxide (SrO) on the alkaline depolymerization of polyethylene terephthalate (PET). For each run, 5 g of PET flakes were placed in a flat-bottom quartz tube with 0.1 M NaOH and the selected catalyst at concentration of 1% by weight of PET. The reaction was conducted inside a sound-insulated box containing an ultrasonic dismembrator probe (amplitude 103.6 μm), six UV grow light panels (10 W each, total 60 W), and a magnetic stirrer. To prevent overheating, a multi-stage cooling system was installed, consisting of a water coil around the ultrasonic converter head, a fan directed at the probe, and a refrigeration system along the box walls. An airline from an air pump was introduced to enhance mixing and oxidation, while a thermocouple continuously monitored temperature. The reaction proceeded for 2 hours under constant ultrasonic amplitude, after which the mixture was cooled to room temperature. Unreacted PET (UnPET) was separated by sieving and rinsed with deionized water to remove residual NaOH. The filtrate, containing disodium terephthalate (Na-TPA), was acidified with concentrated H₂SO₄ added dropwise under ice cooling until the pH reached 1–2, yielding precipitated terephthalic acid (TPA). The TPA was collected by vacuum filtration, washed with deionized water until neutral, and dried at 110 °C for 12 hours. Catalysts were recovered from the filtrate via centrifugation and vacuum filtration, then dried overnight and calcined at 600 °C to remove any micro-residual PET. The amount of UnPET was weighed to calculate PET conversion.
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- PET conversion (%) using five metal oxide catalysts in a 1% by weight of PET under ultrasonication at an amplitude of 103.6 μm and UV light.
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Researchers conduct an alkaline depolymerization of PET using 0.1 M NaOH under ultrasonication (amplitude 103.6 μm) and UV irradiation to investigate the catalytic performance of five metal oxides zinc oxide (ZnO), zinc ferrite (ZnFe₂O₄), yttrium oxide (Y₂O₃), iron(III) oxide (Fe₂O₃), and strontium oxide (SrO) each applied at a 1% loading based on PET weight. What order (from highest to lowest) would you expect for the PET conversion among these catalysts under the described conditions?
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From highest to lowest: SrO, Y₂O₃, ZnO, ZnFe₂O₄ and Fe₂O₃
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- Alkaline depolymerization: is a chemical reaction that occurs in the presence of alkaline medium (0.1 M NaOH), breaking down polymer chains.
- PET conversion: is the ratio of initial weight of PET before the reaction, and weight of unreacted PET after the reaction and sieve separation.
-Ultrasonication: a physical technique that applies high-frequency sound to creates microbubbles that continuously collapse due to compression and expansion phases, leading to the generation of shock waves and shear forces on the PET surface; which further enhances the continuous stretching and/or elongation of the polymer chains promoting chain scission.
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[{"label":"RBK Item","value":"-Ultrasonication: a physical technique that applies high-frequency sound to creates microbubbles that continuously collapse due to compression and expansion phases, leading to the generation of shock waves and shear forces on the PET surface; which further enhances the continuous stretching and/or elongation of the polymer chains promoting chain scission."},{"label":"Title","value":"Mechanochemical Degradation and Recycling of Synthetic Polymers"},{"label":"URL","value":"https://onlinelibrary.wiley.com/doi/full/10.1002/anie.202300768"},{"label":"Date","value":"April 01, 2023"},{"label":"Justification (\"Paywalled\", \"OA\", \"Other (justify)\")","value":"OA"}]
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Chemistry
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Physical Chemistry
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Numerical Values
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Computing Nucleation Rates from Confined Equilibria: The Critical ClusterEquivalence Principle
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https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/68efa3e5dfd0d042d19fbe4b/original/computing-nucleation-rates-from-confined-equilibria-the-critical-cluster-equivalence-principle.pdf
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Oct 17, 2025
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Eight molecular dynamics simulations of sodium chloride (NaCl) crystallization from aqueous solution were conducted. The simulations were performed in the NVT (canonical) ensemble at T = 298 K, using the Joung and Cheatham force field with the SPC/E water model (JC-SPC/E). To identify the steady-state crystalline clusters ($n_{ss}$), a classification criterion was used based on the local bond-order parameter ($\overline{q}_{6} \ge 0.2$) and ionic coordination number ($CN \ge 3$). These simulations were used to test the Critical Cluster Equivalence Principle (CEP) for multi-component solutions by solving an optimization problem based on the first derivative of the Helmholtz free energy, $d\beta\Delta F/dn$.
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-Steady-state crystalline cluster size ($n_{ss,i}$) for eight different simulations.Solute mole fraction ($x(n_{ss,i})$) corresponding to each steady-state cluster.
-Equilibrium solute mole fraction ($x^{*}$) determined by solving the optimization problem.
Effective surface energy parameter ($\sigma^{\prime}$) determined by solving the optimization problem.
-Equilibrium molality ($m^{*}$) derived from the predicted equilibrium mole fraction ($x^{*}$).
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Eight NVT molecular dynamics simulations of NaCl solutions were performed at 298 K, using the JC-SPC/E force field. By identifying the steady-state cluster size ($n_{ss}$) and corresponding solute mole fraction ($x(n_{ss})$) for each simulation, the Critical Cluster Equivalence Principle (CEP) was applied. Using a minimization algorithm based on the Helmholtz free energy derivative, the equilibrium solute mole fraction ($x^{*}$) was determined for this specific force field. Based on this analysis, what is the predicted equilibrium solubility (molality, $m^{*}$) in mol kg$^{-1}$ for the JC-SPC/E NaCl model?
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$m^{*} = [3.70 - 4.10]$ mol kg$^{-1}$ (derived from $3.90 \pm 0.20$ mol kg$^{-1}$).
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-Nucleation is the process where a new, stable phase (like a crystal) forms from a metastable parent phase (like a solution).
-Classical Nucleation Theory (CNT) describes the free energy of forming a cluster, balancing a favorable bulk term (driving force) against an unfavorable surface energy cost.
-The Critical Cluster Equivalence Principle (CEP) is a framework stating that stable equilibrium clusters in confined simulations (like NVT) are equivalent to unstable critical nuclei in open, macroscopic systems.
-NaCl (sodium chloride) is a model system used for studying crystal nucleation.
The Joung and Cheatham (JC-SPC/E) model is a specific empirical force field used to simulate aqueous NaCl solutions.
-Solubility (often given as $m^{*}$ in molality) is the equilibrium concentration of a solute in a solvent at a given temperature.
-The Helmholtz free energy ($\Delta F$) is the relevant thermodynamic potential for a system at constant volume and temperature (NVT ensemble).
-The local bond-order parameter ($\overline{q}_{6}$) is a computational metric used to identify and distinguish crystalline (ordered) structures from disordered (liquid) environments.
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Chemistry
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Materials Chemistry
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Free-Format Question
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Preparation of Poly(vinylidene fluoride-co-hexafluoropropylene) Doped Cellulose Acetate Films for the Treatment of Calcium-Based Hardness from Aqueous Solution
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https://www.mdpi.com/2673-7167/5/4/45
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October 20, 2025
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Researchers fabricated cellulose acetate (CA), poly(vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP), and PVDF-HFP/CA films for the removal of Ca2+ ions from water. All chemical compounds employed for film synthesis were analytical-grade (Merck Life Sciences, South Africa).
First, CA films were prepared using a phase inversion method in which CA (0.900 g) and polyethylene glycol (PEG) (0.2 g) were dissolved in dimethylformamide (DMF) (10 mL) and stirred at 80°C for 2 h. The solution was kept overnight in a silica gel desiccator, then cast onto a glass plate using a 180 µm thick casting knife (Elcometer 3580, Elcometer Limited, UK), washed with deionized water, and air-dried at room temperature.
Similarly, PVDF-HFP films were fabricated by dissolving PVDF-HFP (1.00 g) and PEG (0.2 g) in DMF (10 mL), stirring at 80°C for 2 h, and settlling overnight in a silica gel desiccator. The mixture was cast onto a glass plate using a using an Elcometer 3580 casting knife (Elcometer Limited, UK) with a 180 µm gap, partially dried at 80°C for 30 s, and immersed in 5°C deionized water to induce phase inversion. The produced films were then rinsed with deionized water and air-dried at room temperature.
For the 3 wt.% PVDF-HFP/CA films, CA (0.97 g) was dissolved in DMF (9 mL) with PEG (1 mL) by stirring at 600 rpm at 60 ºC, to render a cellulose acetate solution. Subsequently, PVDF-HFP polymer (0.03 g) was incorportaed into the cellulose acetate solution to form a 3 wt.% PVDF-HFP/CA solution. 3 wt.% PVDF-HFP/CA films were produced from the given solution by following the same steps as for the PVDF-HFP films.
The films produced were characterized by thermogravimetric analysis (TGA), using a Perkin Elmer STA 4000 analyser, assessing mass changes in the films (% initial weight) across various temperatures (0 - 900 ºC), thereby evaluating the thermal stability of the specimens.
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- Weight (% initial weight) of CA, PVDF-HFP and 3 wt.% PVDF-HFP/CA films across the temperature range of 0 - 900 ºC (Thermogravimetric analysis).
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Researchers fabricated cellulose acetate (CA), poly(vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP), and PVDF-HFP/CA films through a phase inversion technique. CA films were prepared with 0.9 g CA and 0.2 g polyethylene glycol (PEG). PVDF-HFP films were prepared with 1 g PVDF-HFP and 0.2 g PEG. 3 wt.% PVDF-HFP/CA films were prepared with 0.97 g CA, 0.03 g of PVDF-HFP polymer and 1 mL PEG. All film components were dissolved in dimethylformamide (DMF), at a final volume of 10 mL. Solutions were settled overnight in a silica gel desiccator, then cast onto a glass plate using a 180 µm thick casting knife (Elcometer 3580, Elcometer Limited, UK). After casting, PVDF-HFP-containing films were partially dried at 80°C for 30 s, and immersed in 5°C deionized water to induce phase inversion. All films were washed with deionized water, and air-dried at room temperature. The films produced were characterized by thermogravimetric analysis (TGA), and mass changes (% initial weight) were recorded across various temperatures (0 - 900 ºC). Which are the expected mass change values (% initial weight) at 500 ºC for the CA and PVDF-HFP films?
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Mass change (% initial weight) at 500 ºC: CA = 7.5 - 17.5%; PVDF-HFP = 20 - 30%. Note: No CI/SE/SD reported → fallback ±5 percent points applied over the values of 12.5% (CA) and 25% (PVDF-HFP).
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- Poly(vinylidene fluoride-hexafluoropropylene) (PVDF-HFP) is a polymer with excellent dielectric properties, mechanical strength, and elevated ionic conductivity that has been employed for manufacturing membranes for water disinfection.
- Cellulose acetate (CA) is a polymer that when incorporated into PVDF-HFP membranes significantly enhances their porosity, electrolyte uptake, ionic conductivity, and hydrophilicity.
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[{"label":"RBK Item","value":"- Poly(vinylidene fluoride-hexafluoropropylene) (PVDF-HFP) is a polymer with excellent dielectric properties, mechanical strength, and elevated ionic conductivity that has been employed for manufacturing membranes for water disinfection."},{"label":"Title","value":"Characterization of poly(vinylidene fluoride–hexafluoropropylene) (PVdF–HFP) electrolytes complexed with different lithium salts"},{"label":"URL","value":"https://www.sciencedirect.com/science/article/abs/pii/S0014305704003106"},{"label":"Date","value":"October 14, 2004"},{"label":"Justification (\"Paywalled\", \"OA\", \"Other (justify)\")","value":"Paywalled version is the external reference cited by the paper for the given RBK item"},{"label":"RBK Item","value":"- Cellulose acetate (CA) is a polymer that when incorporated into PVDF-HFP membranes significantly enhances their porosity, electrolyte uptake, ionic conductivity, and hydrophilicity."},{"label":"Title","value":"Cellulose-based Li-ion batteries: a review"},{"label":"URL","value":"https://link.springer.com/article/10.1007/s10570-013-9973-8"},{"label":"Date","value":"June 19, 2013"},{"label":"Justification (\"Paywalled\", \"OA\", \"Other (justify)\")","value":"Paywalled version is the external reference cited by the paper for the given RBK item"}]
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Physics
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Photonics
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Numerical Values
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Reversing Annealing-Induced Optical Loss in Diamond Microcavities
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https://arxiv.org/abs/2510.03585
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October 4, 2025
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Diamond microdisk optical resonators were fabricated from an optical grade single crystal (<100>-orientation) diamond synthesized by chemical vapor deposition. The micro disk optical cavities were patterned using quasi-isotropic etching with an O$_2$-plasma to diameters ranging 5 to 8 µm and ~940 nm thickness, supported by thin pedestals. The sample was subjected to annealing in a home-built vacuum setup consisting of a vacuum chamber housing a heater. It was set in a custom-made molybdenum holder sitting on top of the heating element, and a molybdenum heat shield was placed on top of the heater to avoid excessive heating due to radiation. The chamber was brought to a base vacuum level of 10$^{−9}$ mbar, and the heater temperature was slowly ramped from room temperature to 1200 °C in 200 °C intervals at a rate of 1 °C per minute, with intermediate wait times of 120 minutes between intervals.
The diamond sample was cleaned pre and post annealing using an equal mixture of H$_2$SO$_4$, HNO$_3$, and HClO$_4$. The bath was applied at a constant temperature of 250 °C for 120 minutes in a glass flask fitted with a water-cooled reflux condenser in a dedicated fume hood. After extraction, the sample was repeatedly rinsed in ultra pure water (ASTM type II grade) and blow-dried with N$_2$. Characterization of microdisk optical modes was performed on the clean sample pre and post annealing using a swept wavelength laser (Santec TSL-710) in the 1480-1640 nm wavelength range to measure the transmission spectra of a dimpled fiber taper evanescently coupled to individual devices.
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- Fiber taper transmission spectra in the 1480-1640 nm probed for microdisks of 5, 6, 7 and 8 µm diameters
|
Microdisk optical resonators were etched on a single optical-grade diamond using O$_2$ plasma to diameters of 5 to 8 µm and a thickness of ~940 nm. The sample was cleaned in a tri-acid bath (equal mixture of H$_2$SO$_4$, HNO$_3$, and HClO$_4$) at 250 °C bath for two hours, then rinsed with ultrapure water and blow-tried with N$_2$. The sample was then slowly annealed from room temperature to 1200 °C in a custom vacuum chamber housing a heater and previously evacuated to 10$^{−9}$ mbar. After annealing, the sample was cleaned once again using the same procedure. Characterization of microdisk optical modes was performed on the clean sample pre and post annealing using a swept wavelength laser operating in the 1480 to 1640 nm range. Based on the resulting transmission spectra, what is the average blue-shift magnitude (in nm) of the optical resonance after annealing, if any?
|
[0.18-0.22] nm
Note: No CI/SE/SD provided, so a ±10% fallback was applied to the 0.2 nm value reported on page 4.
|
- Diamond demands aggressive etching recipes for device patterning, which can promote surface damage and increase lattice strain.
- Annealing steps can harm resonator performance by inducing additional losses from changes to surface morphology and other material characteristics.
- Non-diamond (amorphous carbon) layers can be created on the diamond surface from background gas or out-gassing of the annealing system at high temperatures, which can act as a source of optical loss.
- Tri-acid boiling creates an oxygen-terminated diamond surface through oxidation at 250 °C, crucial for the stabilization of spin, charge, and optical properties of nitrogen-vacancy (NV) centers.
|
[{"label":"RBK Item","value":"Diamond demands aggressive etching recipes for device patterning, which can promotes surface damage and increases lattices train."},{"label":"Title","value":"Diamond integrated quantum nanophotonics: spins, photons and phonons"},{"label":"URL","value":"https://ieeexplore.ieee.org/document/9904837"},{"label":"Date","value":"September 28, 2022"},{"label":"Justification (\"Paywalled\", \"OA\", \"Other (justify)\")","value":"OA, referenced in the paper as ref [10]"},{"label":"RBK Item","value":"Non-diamond layers can be created on the diamond surface from background gas or out-gassing of the annealing system at high temperatures."},{"label":"Title","value":"High temperature graphitization of diamond during heat treatment in air and in a vacuum"},{"label":"URL","value":"https://link.springer.com/article/10.1134/S1087659624600315"},{"label":"Date","value":"September 25, 2024"},{"label":"Justification (\"Paywalled\", \"OA\", \"Other (justify)\")","value":"Paywalled, but referenced in the paper as ref [37]"},{"label":"RBK Item","value":"Tri-acid boiling creates an oxygen-terminated diamond surface through oxidation at 250 °C, crucial for the stabilization of spin, charge, and optical properties of nitrogen-vacancy (NV) centers."},{"label":"Title","value":"Diamond surface engineering for molecular sensing with nitrogen—vacancy centers"},{"label":"URL","value":"https://pubs.rsc.org/en/content/articlelanding/2022/tc/d2tc01258h"},{"label":"Date","value":"March 28, 2022"},{"label":"Justification (\"Paywalled\", \"OA\", \"Other (justify)\")","value":"OA, reference in the paper as ref [14]"}]
|
Physics
|
Condensed Matter Physics
|
MCQ
|
Observation of time crystal in a spin maser system
|
https://arxiv.org/abs/2406.15017
|
Apr 30, 2025
|
In this experiment, the researchers employed a hybrid spin maser composed of rubidium and xenon gases contained in a heated vapor cell along with nitrogen as a buffer, in this step, a hot (∼120 ◦C) gaseous Rb-Xe vapor (containing a droplet of natural abundance Rb, 5 torr of isotope enriched 129Xe and 50 torr of buffer gas N2) is pumped with a resonant laser along the z axis, Rb spins are first polarized. Secondly, the Xe spins precess around a DC magnetic field Bz along the z-axis. The rubidium atoms were first optically pumped using a 795 nm laser. They prepare the initial state by first utilizing a 795-nm pump laser in the z axis with a power of approximately 40 mW. After that, they applied a magnetic field along the z-axis (Bz) and continuously monitored the polarization of the Rb atomic spins along the x-direction. This signal is transmitted to the feedback device, where the original signal from the vapor cell is processed, then fed back to the system parameter via the By coil. The collective spin precession of the ensemble was then tracked by a weak 780 nm probe laser whose signal, detected by an optical polarimeter, provided information about the transverse spin component. The probe laser power is kept at approximately 1 mW to prevent signal saturation in the photodetector. This electrical signal was processed by a feedback circuit that amplified it and imposed a controlled phase delay before sending it back through a magnetic coil to generate a transverse magnetic field, which acted on the spins.
|
- Recorded the real-time precession of rubidium spins under both weak and strong feedback strengths.
- Examined Fourier spectra of the measured spin signal.
|
A hybrid spin maser composed of rubidium and xenon gases contained in a heated vapor cell, along with nitrogen as a buffer. The rubidium atoms were first optically pumped using a 795 nm laser to align their spins along an external magnetic field, and this polarization was transferred to the xenon nuclei through spin-exchange collisions. The collective spin precession of the ensemble was then tracked by a weak 780 nm probe laser whose signal, detected by an optical polarimeter, provided information about the transverse spin component. This electrical signal was processed by a feedback circuit. After that, the real-time precession of rubidium spins under both weak and strong feedback strengths and the Fourier spectra of the measured spin signal are measured. Predict which would be the outcome of this experiment.
a) In the presence of weak feedback, in addition to the original peak, a stronger signal suddenly emerges at a lower frequency than the original frequency.
b) In the presence of weak feedback, in addition to the original peak, a stronger signal suddenly emerges at a higher frequency than the original frequency.
c) In the presence of strong feedback, in addition to the original peak, a stronger signal suddenly emerges at a lower frequency than the original frequency.
d) In the presence of strong feedback, in addition to the original peak, a stronger signal suddenly emerges at a higher frequency than the original frequency.
|
d) In the presence of strong feedback, in addition to the original peak, a stronger signal suddenly emerges at a higher frequency than the original frequency.
|
- Feedback is a procedure of modifying system parameters according to the measurement outcomes. Feedback is not instantaneous but is accompanied by a time delay with a characteristic timescale, and thus can be considered a source of retarded interaction.
- If the magnetization of spins is continuously measured and fed back into the system Hamiltonian with a time delay τ, then the dynamics of the spin at time t depend on the spin magnetization at an earlier time (t-τ).
- A spin maser is a self-driven oscillating atomic system, where a phase-coherent feedback is used to maintain the persistent spin oscillation of a macroscopic ensemble of atoms and balance the spin depolarization or decoherence.
- The spin maser is not only of practical significance in geomagnetic measurements and magnetic navigation, but also of fundamental interest in the search for permanent electric dipole moment [44–46] and spin-dependent exotic interactions.
|
[{"label":"RBK Item","value":"Feedback is a procedure of modifying system parameters according to the measurement outcomes. Feedback is not instantaneous but is accompanied by a time delay with a characteristic timescale, and thus can be considered a source of retarded interaction."},{"label":"Title","value":"Feedback-Based Quantum Optimization"},{"label":"URL","value":"https://journals.aps.org/prl/abstract/10.1103/PhysRevLett.129.250502"},{"label":"Date","value":"Dec 13, 2022"},{"label":"Justification (\"Paywalled\", \"OA\", \"Other (justify)\")","value":"Paywalled, but this is cited as reference 28 in the paper"},{"label":"RBK Item","value":" A spin maser is a self-driven oscillating atomic system, where a phase-coherent feedback is used to maintain the persistent spin oscillation of a macroscopic ensemble of atoms and balance the spin depolarization or decoherence."},{"label":"Title","value":"Principles of Operation of the Rubidium Vapor Magnetometer"},{"label":"URL","value":"https://opg.optica.org/ao/abstract.cfm?uri=ao-1-1-61"},{"label":"Date","value":"Jan 1, 1962"},{"label":"Justification (\"Paywalled\", \"OA\", \"Other (justify)\")","value":"Paywalled, but this is cited as reference 38 in the paper"},{"label":"RBK Item","value":"The spin maser is not only of practical significance in geomagnetic measurements and magnetic navigation, but also of fundamental interest in the search for permanent electric dipole moment [44–46] and spin-dependent exotic interactions."},{"label":"Title","value":"Floquet maser"},{"label":"URL","value":"https://www.science.org/doi/10.1126/sciadv.abe0719"},{"label":"Date","value":"Feb 17, 2021"},{"label":"Justification (\"Paywalled\", \"OA\", \"Other (justify)\")","value":"Open-access, this is cited as reference 47 in the paper"}]
|
Physics
|
Condensed matter physics
|
MCQ
|
Identification of formation of amorphous Si phase in SiOxNy films produced by plasma enhanced chemical vapor deposition
|
https://arxiv.org/abs/2510.14701
|
October 16, 2025
|
Researchers deposited nine 300 ± 5 nm thick SiO$_x$N$_y$ films with different relative Si content using plasma-enhanced chemical vapor deposition. The relative Si contents for these films were 0.34, 0.39, 0.41, 0.48, 0.57, 0.64, 0.68, 0.77, and 0.80. The films were characterized via Raman spectroscopy using a 457-nm laser at room temperature and 1 mm sapphire plates as substrate. The Raman signals were detected using a spectrometer equipped with a CCD detector. The power density of the laser did not exceed 10$^3$ W/cm$^2$ to prevent alterations of the film structure.
|
- Raman spectra of the SiO$_x$N$_y$ films with different relative Si content
|
The amorphous Si content in SiO$_x$N$_y$ films can be estimated from the integrated Raman signal of the transverse-optical band at around 476 cm$^{-1}$. To implement this, nine SiO$_x$N$_y$ films were grown with different relative Si content from 0.34 to 0.80 using plasma-enhanced chemical vapor deposition and Raman spectroscopy was performed using a 457-nm excitation laser at room temperature. The Raman spectrum was decomposed into its Gaussian components and then the integrated intensity of the transverse optical (TO) Raman spectral band was calculated for each film. Which of the following outcomes are observed? Mark all the correct options.
A. The Raman spectra feature two distinct peaks in the 400-570 cm$^{-1}$ range.
B. The position of the maximum intensity in the Raman spectra is virtually independent of the Si content of the samples.
C. The half width of the most intense TO band decreases as the amount of Si in the films increases.
D. The integrated intensity increases exponentially with the relative Si content.
|
B. The position of the maximum intensity in the Raman spectra is virtually independent of the Si content of the samples.
C. The half width of the most intense TO band decreases as the amount of Si in the films increases.
|
- Increasing the relative Si content changes the morphology and structure of SiO$_x$N$_y$.
- Raman spectroscopy can detect amorphous Si clusters in as-deposited Si-rich SiO$_x$N$_y$ thin films.
- SiO$_x$N$_y$ thin films with different film stoichiometries can be fabricated by plasma-enhanced chemical vapor deposition
- Raman spectrum of amorphous Si is characterized by a transverse-optical phonon vibrations of Si-Si bands.
|
[{"label":"RBK Item","value":"Increasing the relative Si content changes the morphology and structure of SiO$_x$N$_y$. \n"},{"label":"Title","value":"Structural and morphological studies on SiOxNy thin films\n"},{"label":"URL","value":"https://doi.org/10.1016/j.jnoncrysol.2007.09.063"},{"label":"Date","value":"February 6, 2008"},{"label":"Justification (\"Paywalled\", \"OA\", \"Other (justify)\")","value":"Paywalled, but this is cited as reference 8 in the paper"},{"label":"RBK Item","value":"Raman spectroscopy can detect amorphous Si clusters in as-deposited Si-rich SiO$_x$N$_y$ thin films."},{"label":"Title","value":"Silicon rich silicon oxynitride films for photoluminescence applications"},{"label":"URL","value":"https://doi.org/10.1016/S0040-6090(03)00008-7\n"},{"label":"Date","value":"March 14, 2003"},{"label":"Justification (\"Paywalled\", \"OA\", \"Other (justify)\")","value":"Paywalled, but this is cited as reference 9 in the paper"},{"label":"RBK Item","value":"SiO$_x$N$_y$ thin films with different film stoichiometries can be fabricated by plasma-enhanced chemical vapor deposition"},{"label":"Title","value":"Infrared study of the structure of silicon oxynitride films produced by plasma enhanced chemical vapor deposition"},{"label":"URL","value":"https://doi.org/10.1016/j.jnoncrysol.2023.122502"},{"label":"Date","value":"July 14, 2023"},{"label":"Justification (\"Paywalled\", \"OA\", \"Other (justify)\")","value":"Open-access, this is cited as reference 13 in the paper"},{"label":"RBK Item","value":"Raman spectrum of amorphous Si is characterized by a transverse-optical phonon vibrations of Si-Si bands."},{"label":"Title","value":"Micro-Raman spectroscopy characterization of silicon with different structures irradiated with energetic Bi-ions"},{"label":"URL","value":"https://doi.org/10.1016/j.nimb.2015.08.041"},{"label":"Date","value":"September 11, 2015"},{"label":"Justification (\"Paywalled\", \"OA\", \"Other (justify)\")","value":"Paywalled, but this is cited as reference 25 in the paper"}]
|
Physics
|
Condensed Matter Physics, Material Science
|
MCQ
|
Isothermal Annealing Effects on β-Relaxations and Crystallization Behaviors in Amorphous GeTe
|
https://arxiv.org/abs/2510.13313
|
Oct 15, 2025
|
Researchers prepared amorphous samples of GeTe by magnetron sputtering deposition using stoichiometric targets at a background pressure of 3 × 10⁻³ mbar and an argon flow rate of 20 sccm. Thick layers of several micrometers were sputtered to obtain sufficient powder or flake samples for powder mechanical dynamic spectroscopy (PMS) measurements. Prior to PMS testing, the exfoliated flakes were carefully milled into a fine powder with a uniform particle size. For PMS measurements, a TA Q‑800 dynamic mechanical analyzer (DMA) was employed in combination with a custom‑designed powder container. To ensure data reliability, each measurement used a consistent powder mass of 300 mg, and the torsional force applied to the powder clamp was maintained at 5 pounds. For annealing experiments performed on powder samples within the DMA chamber under argon protection, the chamber temperature was rapidly equilibrated to the target annealing temperature, followed by in‑situ annealing at that temperature for 3 h, and then rapid cooling to room temperature.
|
- Temperature‑dependent relaxation spectra of the amorphous GeTe powder samples were recorded in multi‑frequency strain mode at discrete fixed testing frequencies (0.5, 1, 2, and 8 Hz), with a strain amplitude of 10 μm and a heating rate of 3 K/min, all conducted under an argon atmosphere.
- Viscoelastic loss modulus (E′′) was measured at f = 1 Hz for an as-deposited GeTe
sample.
- Viscoelastic loss modulus (E′′) was measured at f = 1 Hz for a sample annealed at Tₐₙₙ = 166 °C for 3 hrs.
|
Powder mechanical spectroscopy (PMS) measurements allow for measuring viscoelastic loss modulus (E′′) and storage modulus (E’) of powder samples that lack the bulk glass-forming abilities required for conventional dynamic mechanical spectroscopy (DMS) measurements. E’’ and E’ can be used to characterize the α- and β-relaxations in glasses (amorphous and annealed GeTe powdered samples) at a given frequency (f). When time-dependent relaxation spectra were observed for GeTe samples (powdered by magnetron sputtering deposition using stoichiometric targets at a background pressure of 3 × 10⁻³ mbar and an argon flow rate of 20 sccm, with in‑situ annealing at 166 °C for 3 h, and then rapid cooling to room temperature, for the annealed sample) at different frequencies (0.5, 1, 2, 8 Hz), which of the following is the most likely outcome?
A. No pronounced β-relaxation observed in amorphous GeTe samples, showing a positive deviation in the normalized α-relaxation peak compared to the annealed samples.
B. Pronounced β-relaxation vanishes in amorphous GeTe samples with increasing frequency, showing a positive deviation in the normalized α-relaxation peak compared to the annealed samples.
C. Pronounced β-relaxation vanishes in amorphous GeTe samples with increasing frequency, showing a negative deviation in the normalized α-relaxation peak compared to the annealed samples.
D. Pronounced β-relaxation vanishes in amorphous GeTe samples with decreasing frequency, showing a positive deviation in the normalized α-relaxation peak compared to the annealed samples.
|
C. Pronounced β-relaxation vanishes in amorphous GeTe samples with increasing frequency, showing a negative deviation in the normalized α-relaxation peak compared to the annealed samples.
|
- Only in PCMs, excess wings in E’’ have been observed, indicating the presence of β-relaxations.
|
[{"label":"RBK Item","value":"Only in PCMs, excess wings in E’’ have been observed, indicating the presence of β-relaxations."},{"label":"Title","value":"Uncovering β-relaxations in amorphous phase-change materials"},{"label":"URL","value":"https://www.science.org/doi/10.1126/sciadv.aay6726"},{"label":"Date","value":"Jan 10, 2020"},{"label":"Justification (\"Paywalled\", \"OA\", \"Other (justify)\")","value":"OA"}]
|
Physics
|
Quantum Atomic Physics / Atomtronics
|
Free-Format Question
|
Multi-loop and Multi-axis Atomtronic Sagnac Interferometry
|
https://arxiv.org/abs/2504.20345
|
Apr 29, 2025
|
Researchers implemented a Bose–Einstein condensate (BEC) interferometer using approximately 10³⁸⁷Rb atoms confined within a two-dimensional toroidal optical waveguide generated by laser beams shaped through a spatial light modulator (SLM). The ⁸⁷Rb atoms were generated using a crossed optical dipole trap with 1064nm beams. The horizontal and vertical beams have waists of 17µm and 88µm, respectively. The atoms were cooled using delta-kick cooling, achieving a final effective temperature of 1.1nK and an axial size of 120µm (Thomas-Fermi FWHM) in the guide. To enable this collimation, the vertical beam is time-averaged (painted) at 10kHz to create a large harmonic lens of FWHM size 180µm. Controlled modulation of the optical potential drove the condensate along the ring to execute multiple orbits (multi-loop) and axis reorientation (multi-axis). The delta-kick collimation and focusing lens durations are 0.9ms and 2ms, respectively. The guide translation is performed by a one-axis acousto-optic deflector (AOD, IntraAction ATD274HD6), placed one focal length (f) behind a f = 20cm plano-convex lens. By changing the RF frequency to the AOD, the beam after the lens is translated by 338µm for a 1MHz change in the RF frequency. A double-square intensity pulse is used as a symmetric beam splitter, and a Gaussian pulse is used for the mirror operation on BECs. The beamsplitter pulse is composed of two square pulses of 22.3µs and 21.2µs with a no-light gap of 37.9µs in between, and the Bragg laser is ≈ 12.6GHz. Immediately after the recombination pulse, a strong delta-kick pulse is applied, focusing all three momentum states into a tight spot within 20ms, at which point the states are separated by 260µm. And use absorption imaging to count the number of atoms in the three peaks with no time of flight.
|
- Population fraction (in fraction) against the interferometer phase without phase correction.
- Population fraction (in fraction) against the interferometer phase with phase correction.
|
Researchers implemented a Bose–Einstein condensate (BEC) interferometer using approximately 10³⁸⁷Rb atoms confined within a two-dimensional toroidal optical waveguide generated by laser beams shaped through a spatial light modulator (SLM). The atoms were cooled using delta-kick cooling. To enable this collimation, the vertical beam is time-averaged (painted) to create a large harmonic lens. Controlled modulation of the optical potential drove the condensate along the ring to execute multiple orbits (multi-loop) and axis reorientation (multi-axis). The guide translation is performed by a one-axis acousto-optic deflector (AOD, IntraAction ATD274HD6). A double-square intensity pulse is used as a symmetric beam splitter, and a Gaussian pulse is used for the mirror operation on BECs. Immediately after the recombination pulse, a strong delta-kick pulse is applied, focusing all three momentum states into a tight spot. And use absorption imaging to count the number of atoms in the three peaks with no time of flight. To measure the phase correction, two navigation-grade accelerometers are installed. Predict accelerometer correction depends upon which parameters?
|
This method of accelerometer correction depends only on interferometer time T.
|
- A higher axial guide curvature or interferometer T both shorten the time wave-packets take to overlap again at the end.
-We noticed that the waveguide waist moved for a duration of a few seconds due to the thermal lensing caused by the AOD.
-with an increase in the number of loops or Sagnac area, contrast goes down due to technical (not fundamental) issues, and ARW remains of that order as mentioned above.
|
[{"label":"RBK Item","value":"A higher axial guide curvature or interferometer T both shorten the time wave-packets take to overlap again at the end."},{"label":"Title","value":"Confinement effects in a guided-wave atom interferometer with millimeter-scale arm separation"},{"label":"URL","value":"https://journals.aps.org/pra/abstract/10.1103/PhysRevA.78.023619"},{"label":"Date","value":"August 14, 2008"},{"label":"Justification (\"Paywalled\", \"OA\", \"Other (justify)\")","value":"Paywalled, but this is cited as reference 41 in the paper"}]
|
Physics
|
Soft Condensed Matter
|
Free-Format Question
|
Dynamics of Choline Chloride based Deep Eutectic Solvents: Neutron Scattering Study
|
https://arxiv.org/abs/2510.05882
|
October 7, 2025
|
The experiment involves the synthesis of three deep eutectic solvents (DES)—reline (ChCl + urea), glyceline (ChCl + glycerol), and ethaline (ChCl + ethylene glycol)—by combining choline chloride with their respective deuterated hydrogen bond donors (HBDs) in a molar ratio of 1:2. The mixtures are heated to 340 K until a clear, homogeneous solution is achieved. The solutions are then cooled to room temperature (300 K), and the resulting DES systems remain in a liquid state. Quasielastic neutron scattering (QENS) experiments are used to probe the self-diffusion of cholinium ions at molecular length and time scales. QENS experiments are performed on the IRIS spectrometer at the ISIS Neutron and Muon Source, Rutherford Appleton Laboratory (UK). The IRIS spectrometer utilizes a PG (002) analyzer in offset mode, offering an energy transfer range from -0.3 to +1 meV with an energy resolution of approximately 17 µeV. The accessible wave-vector (Q) transfer range is between 0.54 and 1.8 Å⁻¹. A standard vanadium sample is used to calibrate the spectrometer's resolution.
|
- Quasielastic neutron spectra of ethaline, reline, and glyceline were recorded using IRIS spectrometer at ISIS to probe cholinium ion diffusion.
- The jump diffusion coefficient of the cholinium ion (Ch⁺) in ethaline, reline, and glyceline, as a function of temperature (300–365 K).
|
Three deep eutectic solvent systems (reline, glyceline, and ethaline) were synthesized, comprising choline chloride (ChCl) mixed with urea, glycerol, and ethylene glycol in a 1:2 molar ratio. Each mixture was heated to 340 K until a clear, homogeneous solution was achieved, and the solution was cooled to room temperature (300 K) in a liquid state. Quasielastic neutron scattering (QENS) experiments were performed using the IRIS spectrometer at the ISIS Neutron and Muon Source, Rutherford Appleton Laboratory (UK). QENS measurements were carried out at five temperatures: 300; 315; 330; 355; and 365 K. Which DES will have the steepest dependence of cholinium ion jump diffusion coefficient on temperature?
|
Based on the temperature-dependent measurements of the jump diffusion coefficient of ethaline, the jump diffusion coefficient of cholinium ions in ethaline should have the steepest dependence on temperature.
|
- Deep eutectic solvents (DESs) are an emerging class of sustainable solvents that have gained attention as environmentally friendly alternatives to conventional room-temperature ionic liquids (RTILs). They are typically formed by combining a quaternary ammonium salt with a molecular hydrogen bond donor (HBD), resulting in a eutectic mixture with a melting point significantly lower than that of the individual components.
- Quasielastic neutron scattering (QENS) experiments are used to probe the self-diffusion of cholinium ions at molecular length and time scales. The dynamics are modeled as a combination of jump diffusion of the molecular center of mass and localized translation within transient hydrogen-bond cages.
- To elucidate the underlying diffusion mechanism, the QENS spectra is explicitly modeled using a microscopic diffusion mechanism that involves contributions from different dynamic processes. The QENS spectra were modeled using a two-component diffusion model incorporating both localized translation motion within transient cages and jump diffusion of the molecular center of mass.
- To gain quantitative insight into the mobility of Ch⁺, the width of the Lorentzian component was modelled using the Singwi-Sjolander (SS) model.
|
[{"label":"RBK Item","value":"Deep eutectic solvents (DESs) are an emerging class of sustainable solvents that have gained attention as environmentally friendly alternatives to conventional room-temperature ionic liquids (RTILs). They are typically formed by combining a quaternary ammonium salt with a molecular hydrogen bond donor (HBD), resulting in a eutectic mixture with a melting point significantly lower than that of the individual components. "},{"label":"Title","value":"Novel solvent properties of choline chloride/urea mixtures"},{"label":"URL","value":"https://doi.org/10.1039/B210714G"},{"label":"Date","value":"November 26, 2002"},{"label":"Justification (\"Paywalled\", \"OA\", \"Other (justify)\")","value":"OA; this is reference 1 in the paper."},{"label":"RBK Item","value":"To elucidate the underlying diffusion mechanism, the QENS spectra is explicitly modeled using a microscopic diffusion mechanism that involves contributions from different dynamic processes. The QENS spectra were modeled using a two-component diffusion model incorporating both localized translation motion within transient cages and jump diffusion of the molecular center of mass."},{"label":"Title","value":"Transport Mechanism of Acetamide in Deep Eutectic Solvents"},{"label":"URL","value":"https://doi.org/10.1021/acs.jpcb.9b11137"},{"label":"Date","value":"February 4, 2020"},{"label":"Justification (\"Paywalled\", \"OA\", \"Other (justify)\")","value":"The paper is paywalled, but this is cited as reference 8 in the paper. The paper is also important to understand the diffusion mechanisms of deep elastic solvents."},{"label":"RBK Item","value":"To gain quantitative insight into the mobility of Ch⁺, the width of the Lorentzian component was modelled using the Singwi-Sjolander (SS) model."},{"label":"Title","value":"Diffusive Motions in Water and Cold Neutron Scattering"},{"label":"URL","value":"https://doi.org/10.1103/PhysRev.119.863"},{"label":"Date","value":"August 1, 1960"},{"label":"Justification (\"Paywalled\", \"OA\", \"Other (justify)\")","value":"The paper is paywalled, but this is cited as reference 11 in the paper. It is also essential to understand the modeling of the width of the Lorentzian component using the Singwi-Sjolander (SS) model."}]
|
Physics
|
High-Energy Nuclear Physics/Particle Physics
|
MCQ
|
News on strangeness production from the NA61/SHINE experiment
|
https://arxiv.org/abs/2508.14998
|
Aug 20, 2025
|
The NA61/SHINE experiment at the CERN Super Proton Synchrotron North Area used a fixed-target setup with an argon (Ar) beam incident on a scandium (Sc) target to study central collisions, selected as the 10% most central based on forward energy measurements. Beam momenta were 40 A GeV/c and 75 A GeV/c, corresponding to center-of-mass energies per nucleon pair of √s_NN = 8.77 GeV and 11.9 GeV. The detector included large-acceptance tracking and particle identification capabilities, with dE/dx measurements for charged kaons, combined time-of-flight and dE/dx for enhanced identification, and decay topology reconstruction for neutral K⁰_S mesons via the channel K⁰_S → π⁺ + π⁻ with a branching ratio of 69.2%. Yields were corrected for detector acceptance, reconstruction efficiency, selection cuts, and branching ratios, focusing on hadrons produced in strong interactions and electromagnetic decays.
|
- Mid-rapidity yields (dn/dy at 0<y<0.2) of charged kaons K⁺ and K⁻ in the 10% most central Ar+Sc collisions at beam momenta of 40A and 75A GeV/c
- Mid-rapidity yields (dn/dy at 0<y<0.2) of neutral kaons K⁰_S identified via decay topology reconstruction (K⁰_S → π⁺ + π⁻) in the 10% most central Ar+Sc collisions at beam momenta of 40A and 75A GeV/c
- Particle identification methods: dE/dx measurements for charged kaons and combined time-of-flight with dE/dx for enhanced identification
|
In central Ar+Sc collisions at SPS energies, strangeness production was measured using mid-rapidity yields of charged K⁺, K⁻ and neutral K⁰_S mesons, with corrections for acceptance and decays. Given the near-isospin symmetry of Ar and Sc nuclei (valence quarks u ≈ d within 6%), the ratio R_K = (K⁺ + K⁻) / (2 K⁰_S) was evaluated. Which of the following outcomes is most likely?
A) The ratio R_K is less than 1, due to preferential neutral kaon production from isospin effects.
B) The ratio R_K is approximately 1, consistent with expected equality from nuclear symmetry.
C) The ratio R_K is greater than 1, showing an unexpected excess of charged kaons over neutral ones.
|
C) The ratio R_K is greater than 1, showing an unexpected excess of charged kaons over neutral ones.
|
- Strangeness production enhancement in heavy-ion collisions relative to baseline proton-proton collisions is considered one of the earliest proposed signatures of quark-gluon plasma formation.
- Kaons (K mesons) containing strange quarks are identified in experiments through specific detection methods: charged kaons via energy loss (dE/dx) measurements and time-of-flight techniques, while neutral K⁰_S mesons are reconstructed through their characteristic decay topology into π⁺π⁻ pairs.
- In collisions of nearly isospin-symmetric nuclei (where the number of up and down valence quarks are approximately equal), particle production models predict approximately equal abundances of charged and neutral kaons.
|
[{"label":"RBK Item","value":"Strangeness production enhancement in heavy-ion collisions relative to baseline proton-proton collisions is considered one of the earliest proposed signatures of quark-gluon plasma formation."},{"label":"Title","value":"Strangeness Production in the Quark-Gluon Plasma"},{"label":"URL","value":"https://doi.org/10.1103/PhysRevLett.48.1066"},{"label":"Date","value":"April 19, 1982"},{"label":"Justification (\"Paywalled\", \"OA\", \"Other (justify)\")","value":"Paywalled - This foundational paper (Ref. [1] in the main paper) established strangeness enhancement as a QGP signature. It's relevant to the OPQ because it provides the theoretical context for why kaon production measurements in Ar+Sc collisions are significant for understanding strongly interacting matter."},{"label":"RBK Item","value":"Kaons (K mesons) containing strange quarks are identified in experiments through specific detection methods: charged kaons via energy loss (dE/dx) measurements and time-of-flight techniques, while neutral K⁰_S mesons are reconstructed through their characteristic decay topology into π⁺π⁻ pairs."},{"label":"Title","value":"NA61/SHINE facility at the CERN SPS: beams and detector system"},{"label":"URL","value":"https://iopscience.iop.org/article/10.1088/1748-0221/9/06/P06005/pdf"},{"label":"Date","value":"June 9, 2014"},{"label":"Justification (\"Paywalled\", \"OA\", \"Other (justify)\")","value":"OA - This detector paper (Ref. [3] in the main paper) describes the particle identification techniques used in NA61/SHINE. It's relevant to the OPQ because accurate identification of both charged and neutral kaons is essential for measuring the R_K ratio."},{"label":"RBK Item","value":"In collisions of nearly isospin-symmetric nuclei (where the number of up and down valence quarks are approximately equal), particle production models predict approximately equal abundances of charged and neutral kaons."},{"label":"Title","value":"Evidence of isospin-symmetry violation in high-energy collisions of atomic nuclei"},{"label":"URL","value":"https://www.nature.com/articles/s41467-025-57234-6"},{"label":"Justification (\"Paywalled\", \"OA\", \"Other (justify)\")","value":"OA - This paper (Ref. [10] in the main paper) discusses isospin symmetry expectations for kaon production. It's relevant to the OPQ because it explains why R_K ≈ 1 would be expected in Ar+Sc collisions if conventional production mechanisms were dominant."}]
|
Physics
|
Experimental Nuclear Physics
|
Free-Format Question
|
High-resolution multi-reflection time-of-flight mass spectrometer for exotic nuclei at IGISOL
|
https://arxiv.org/abs/2508.10048
|
August 12, 2025
|
Researchers investigated the performance of a Multi-Reflection Time-of-Flight Mass Spectrometer (MR-ToF-MS) at the IGISOL facility using stable ³⁹K⁺ ions from the off-line ion station to evaluate the instrument's mass-resolving power. The ions were prepared in the upgraded Radio-Frequency Quadrupole (RFQ) cooler-buncher, which features a Mini-Buncher section. The experiment involved varying the number of revolutions (n) completed by the ions inside the spectrometer from 0 (shoot-through) to over 1000 (~20 ms total flight) by delaying the extraction pulse via the pulsed drift-tube switch after injection at a base trapping energy of ~1 keV kinetic energy (via 1 kV in-trap lift pulse), with mirror electrode voltages tuned for 1 keV trapping as E1 = -1871.79 V, E2 = -1655.06 V, E3 = 110.89 V, E4 = 905.90 V, E5 = 1014.11 V, and E6 = 1469.51 V. These tests were conducted under three distinct pulsed drift-tube voltage conditions, corresponding to an energy change per revolution (lambda) of 3 eV, 6 eV, and 15 eV. Ion bunches were transported on a 30 kV floated high-voltage platform via extraction to 2 kV below the RFQ, a 90° quadrupole bender, XY steerers, a quadrupole triplet, and an einzel lens, into the ultra-high vacuum MR-ToF-MS chamber (<10⁻⁷ mbar operating), where detection occurred via a MagneToF with 200 ps time-to-digital converter resolution in event-by-event storage, timed by a master-slave timing system with optical fiber synchronization for RF phase-locked extraction on the high-voltage platform; electrode supply stability limited long-term R ≲9×10⁴ without drift correction.
|
- The peak mass-resolving power (R) of the spectrometer as a function of the number of ion revolutions (n) at lambda 3 eV.
- The peak mass-resolving power (R) of the spectrometer as a function of the number of ion revolutions (n) at lambda 6 eV.
- The peak mass-resolving power (R) of the spectrometer as a function of the number of ion revolutions (n) at lambda 15 eV.
|
A Multi-Reflection Time-of-Flight Mass Spectrometer (MR-ToF-MS) was used to analyze the behavior of (39)K+ ions. The experiment involved varying the number of revolutions (n) completed by the ions inside the spectrometer from 0 to over 1000 (~20 ms total flight) by delaying the extraction pulse via the pulsed drift-tube switch after injection at a base trapping energy of ~1 keV kinetic energy, with mirror electrode voltages tuned for 1 keV trapping as E1 = -1871.79 V, E2 = -1655.06 V, E3 = 110.89 V, E4 = 905.90 V, E5 = 1014.11 V, and E6 = 1469.51 V. These tests were conducted under three distinct pulsed drift-tube voltage conditions, corresponding to an energy change per revolution (lambda) of 3 eV, 6 eV, and 15 eV. Based on this setup, predict how ToF changes depending on the trapping energy?
|
The TOF increases linearly with the trapping energy.
|
- The MRToF-MSs are designed to be energy-isochronous at a higher order, including isochronicity not only with respect to energy but also other parameters, such as ion angle and position at injection.
- Estimates of the mass-resolving power are typically found with a series expansion of the ion time-of-flight, with varying degrees of detail to account for temporal focusing
- When using the pulsed drift-electrode to change the ion trapping energy in the MR-ToF-MS by a small amount (lambda), it mostly affects tn as the trapped path in the MR-ToF-MS is far longer than the MR-ToF-MS portion of the shoot-through path.
|
[{"label":"RBK Item","value":"The MRToF-MSs are designed to be energy-isochronous at a higher order, including isochronicity not only with respect to energy but also other parameters, such as ion angle and position at injection."},{"label":"Title","value":"Chapter 1 Charged Particles in Electromagnetic Fields"},{"label":"URL","value":"https://www.sciencedirect.com/science/article/abs/pii/S1076567009016012?via%3Dihub"},{"label":"Date","value":"July 14, 2009"},{"label":"Justification (\"Paywalled\", \"OA\", \"Other (justify)\")","value":"Paywalled, but this is cited as reference 26 in the paper"},{"label":"RBK Item","value":"Estimates of the mass-resolving power are typically found with series expansion of ion time-of-flight, with varying degrees of detail to account for temporal focusing"},{"label":"Title","value":"Static-mirror ion capture and time focusing for electrostatic ion-beam traps and multi-reflection time-of-flight mass analyzers by use of an in-trap potential lift"},{"label":"URL","value":"https://www.sciencedirect.com/science/article/abs/pii/S1387380611004775?via%3Dihub"},{"label":"Date","value":"Mar 1, 2012"},{"label":"Justification (\"Paywalled\", \"OA\", \"Other (justify)\")","value":"Paywalled, but this is cited as reference 25 in the paper"}]
|
Physics
|
Physics/Quantum Physics
|
MCQ
|
Optically detected nuclear magnetic resonance of coherent spins in a molecular complex
|
https://arxiv.org/pdf/2509.01467
|
September 1, 2025
|
Researchers studied the ground-state nuclear quadrupole transitions of the ¹⁵¹Eu³⁺ isotope in a millimeter-sized [Eu(BA)₄(pip)] molecular crystal at a temperature of 4.2 K. To precisely determine the transition frequencies and probe the spin inhomogeneity, they performed Optically Detected Nuclear Magnetic Resonance (ODNMR). After preparing the nuclear spin state via optical pumping (creating a spectral pit), a 1 ms radio-frequency (RF) pulse with a power of ~92 W was applied using a superconducting coil. A weak optical probe pulse was then used to read out the resulting fluorescence signal. The RF frequency was swept point by point to measure the ODNMR spectrum for the two ground-state resonances.
|
- ODNMR spectrum for the two ground-state nuclear quadrupole transitions.
- Center frequencies of the ground-state resonances.
- Inhomogeneous linewidth (full width at half maximum, FWHM) of the two ground-state resonances.
|
In a ¹⁵¹Eu³⁺-based molecular crystal at 4.2 K, the inhomogeneous linewidths of the two ground-state nuclear quadrupole transitions were measured using Optically Detected Nuclear Magnetic Resonance (ODNMR). The transitions were centered at approximately 21.5 MHz and 34.0 MHz. Which of the following outcomes best describes the comparison of their full width at half maximum (FWHM) inhomogeneous linewidths?
A) The ~21.5 MHz transition was significantly broader (FWHM ≈ 220 kHz), while the ~34.0 MHz transition was much narrower (FWHM ≈ 90 kHz).
B) The ~34.0 MHz transition was significantly broader (FWHM ≈ 220 kHz), while the ~21.5 MHz transition was much narrower (FWHM ≈ 90 kHz).
C) Both transitions exhibited similarly narrow inhomogeneous linewidths (FWHM ≈ 90 kHz).
D) Both transitions exhibited similarly broad inhomogeneous linewidths (FWHM ≈ 220 kHz).
|
A) The ~21.5 MHz transition was significantly broader (FWHM ≈ 220 kHz), while the ~34.0 MHz transition was much narrower (FWHM ≈ 90 kHz).
|
- Europium-based molecular complexes: Certain rare-earth ions like Eu³⁺ can be incorporated into molecular crystals. These systems are investigated for quantum technologies because they possess nuclear spins that can be addressed optically.
- Nuclear Quadrupole Resonance (NQR): This is a form of magnetic resonance that arises from the interaction of the nuclear electric quadrupole moment of a nucleus with the local electric field gradient. It allows for probing nuclear spin transitions without an external magnetic field.
- Optically Detected Nuclear Magnetic Resonance (ODNMR): A technique that combines optical spectroscopy and nuclear magnetic resonance. It uses light (optical pumping and probing) to initialize and read out the state of nuclear spins, offering higher sensitivity than conventional NMR.
- Inhomogeneous Linewidth: In a crystal, microscopic imperfections and strains cause slight variations in the local environment of each ion. This leads to a distribution of transition frequencies for the ensemble of ions, and the width of this distribution is known as the inhomogeneous linewidth.
|
[{"label":"RBK Item","value":"Europium-based molecular complexes: Certain rare-earth ions like Eu³⁺ can be incorporated into molecular crystals. These systems are investigated for quantum technologies because they possess nuclear spins that can be addressed optically."},{"label":"Title","value":"Ultra-narrow optical linewidths in rare-earth molecular crystals"},{"label":"URL","value":"https://www.nature.com/articles/s41586-021-04316-2"},{"label":"Date","value":"March 9, 2022"},{"label":"Justification (\"Paywalled\", \"OA\", \"Other (justify)\")","value":"Paywalled \n(The item is used in the main paper, and there are no open-access alternatives; it is the flagship publication regarding the subject matter in the field.)"},{"label":"RBK Item","value":"Optically Detected Nuclear Magnetic Resonance (ODNMR): A technique that combines optical spectroscopy and nuclear magnetic resonance. It uses light (optical pumping and probing) to initialize and read out the state of nuclear spins, offering higher sensitivity than conventional NMR."},{"label":"Title","value":"Optical detection of magnetic resonance"},{"label":"URL","value":"https://mr.copernicus.org/articles/1/115/2020/"},{"label":"Date","value":"June 30, 2020"},{"label":"Justification (\"Paywalled\", \"OA\", \"Other (justify)\")","value":"OA"},{"label":"RBK Item","value":"Inhomogeneous Linewidth: In a crystal, microscopic imperfections and strains cause slight variations in the local environment of each ion. This leads to a distribution of transition frequencies for the ensemble of ions, and the width of this distribution is known as the inhomogeneous linewidth."},{"label":"Title","value":"Advanced holeburning techniques for determination of hyperfine transition properties in inhomogeneously broadened solids applied to Pr3+:Y2SiO5"},{"label":"URL","value":"https://arxiv.org/abs/cond-mat/0408515"},{"label":"Date","value":"August 24, 2004"},{"label":"Justification (\"Paywalled\", \"OA\", \"Other (justify)\")","value":"OA"},{"label":"RBK Item","value":"Inhomogeneous Linewidth: In a crystal, microscopic imperfections and strains cause slight variations in the local environment of each ion. This leads to a distribution of transition frequencies for the ensemble of ions, and the width of this distribution is known as the inhomogeneous linewidth. This applies to both optical transitions and nuclear spin transitions."},{"label":"Title","value":"Hole-burning techniques for isolation and study of individual hyperfine transitions in inhomogeneously broadened solids demonstrated in Pr³⁺:Y₂SiO₅"},{"label":"URL","value":"https://journals.aps.org/prb/abstract/10.1103/PhysRevB.70.214116"},{"label":"Date","value":"December 30, 2004"},{"label":"Justification (\"Paywalled\", \"OA\", \"Other (justify)\")","value":"Paywalled"}]
|
Physics
|
Experimental Condensed Matter Physics
|
Numerical Values
|
Total-area world-record efficiency of 27.03% for 350 cm² commercial-sized single-junction silicon solar cells
|
https://www.nature.com/articles/s41467-025-61128-y
|
July 1, 2025
|
Researchers fabricated industrial-size (350 cm²) crystalline silicon solar cells from phosphorus-doped n-type Czochralski monocrystalline silicon (100) wafers using a passivated emitter and rear contact (PERC) design. The wafers were first cleaned and polished to 130 μm. A 1.7-nm-thick SiO2 layer and a 300-nm-thick intrinsic amorphous silicon (i-a-Si) layer were deposited sequentially on the surface of the pretreated wafers. After that, the deposition of boron-doped poly-Si and borosilicate glass (BSG) is done in a diffusion furnace. After laser crushing of BSG and wet removal of p-type poly-Si in the gap region and n-type region, a 1.5-nm-thick SiO2 layer and a 200-nm-thick i-a-Si layer were grown on both sides of the samples. Phosphorus-doped poly-Si and phosphosilicate glass (PSG) were prepared on the surface of the sample. Subsequently, the PSG in the p-type region and gap region of the samples was removed by laser. For the CMS-based cells, the samples were then directly treated with NaON/IPA mixed solution at a temperature of 68 °C for 6 min. For the HMS-based cells, the pyramids prepared by wet chemical etching were further reconstructed at 70 °C for 2 min using a NaOH solution with a polymer additive. For the HMNS-based cells, samples with an acid-polished front surface were immersed in a mixture solution of NaOH, IPA, and a type of inorganic calcium salt at a temperature of 68 °C for 6 min. Then, Al2O3 and SiNx were sequentially deposited onto the surface of the samples using ALD and plasma-enhanced CVD techniques, respectively. Finally, a silver paste was screen-printed onto the contacts and fired at 780 °C in air ventilation to form electrodes. The cells were characterized under standard AM1.5 G illumination (1000 W m⁻², 25 °C). Efficiency, current–voltage (I–V) curves, and spectral response were measured according to IEC 60904-3 procedures.
|
- Electrical conversion efficiency measured under standard AM 1.5 G illumination (1000 W m⁻², 25 °C).
- Open-circuit voltage (Voc), short-circuit current density (Jsc), and fill factor (FF) recorded from I–V characteristics.
- Efficiency values averaged over three independent samples using the same calibrated solar simulator.
|
An industrial-size (350 cm²) crystalline silicon solar cell from phosphorus-doped n-type Czochralski monocrystalline silicon (100) wafers using a passivated emitter and rear contact (PERC) design. After laser crushing of BSG and wet removal of p-type poly-Si in the gap region and n-type region, a 1.5-nm-thick SiO2 layer and a 200-nm-thick i-a-Si layer were grown on both sides of the samples. Phosphorus-doped poly-Si and phosphosilicate glass (PSG) were prepared on the surface of the sample. The cells were characterized under standard AM1.5 G illumination (1000 W m⁻², 25 °C). Efficiency, current–voltage (I–V) curves, and spectral response were measured according to IEC 60904-3 procedures. Predict the efficiency of a fabricated solar cell (in %).
|
The efficiency of the 350 cm² fabricated solar cell is 26.56 - 27.49 %. (The given SD is ±0.46%, so this is the fallback)
|
- BC cells are normally criticized for their low bifaciality factors due to the materials/structures on the rear side, such as the heavily doped materials and metal grid lines, that may have parasitic light absorption and/or shade light.
- Due to the difference in surface stresses and crystal orientations, the quality of the SiOx film varies between polished and textured surfaces, and the TOPCon structure exhibits significantly better passivation on a planar surface.
- The surface morphology plays a crucial role in reducing surface reflectance, largely determining the proportion of incident light that can refract into the silicon bulk.
|
[{"label":"RBK Item","value":"BC cells are normally criticized for their low bifaciality factors due to the materials/structures on the rear side, such as the heavily doped materials and metal grid lines, that may have parasitic light absorption and/or shade light."},{"label":"Title","value":"Tailoring Interdigitated Back Contacts for High-performance Bifacial Silicon Solar Cells"},{"label":"URL","value":"https://arxiv.org/abs/1811.00647"},{"label":"Date","value":"Nov 1, 2018"},{"label":"Justification (\"Paywalled\", \"OA\", \"Other (justify)\")","value":"Open-access, this is cited as reference 31 in the paper"},{"label":"RBK Item","value":"Due to the difference in surface stresses and crystal orientations, the quality of the SiOx film varies between polished and textured surfaces, and the TOPCon structure exhibits significantly better passivation on a planar surface."},{"label":"Title","value":"Effect of Crystallographic Orientation and Nanoscale Surface Morphology on Poly-Si/SiOx Contacts for Silicon Solar Cells"},{"label":"URL","value":"https://pubmed.ncbi.nlm.nih.gov/31610646/"},{"label":"Date","value":"Oct 30, 2019"},{"label":"Justification (\"Paywalled\", \"OA\", \"Other (justify)\")","value":"Paywalled, but this is cited as reference 32 in the paper"},{"label":"RBK Item","value":"The surface morphology plays a crucial role in reducing surface reflectance, largely determining the proportion of incident light that can refract into the silicon bulk."},{"label":"Title","value":"Surface Modifications for Light Trapping in Silicon Heterojunction Solar Cells: A Brief Review"},{"label":"URL","value":"https://pure.skku.edu/en/publications/surface-modifications-for-light-trapping-in-silicon-heterojunctio/"},{"label":"Date","value":"Aug 1, 2020"},{"label":"Justification (\"Paywalled\", \"OA\", \"Other (justify)\")","value":"Paywalled, but this is cited as reference 36 in the paper"}]
|
Physics
|
Physics/Optics
|
Free-Format Question
|
Ultra-high-precision fused silica micro-hole machining via spherical aberration-assisted filamentation and laser-induced deep etching
|
https://arxiv.org/abs/2510.19100
|
October 21, 2025
|
Researchers fabricated high-precision micro-holes in fused silica using aberration-assisted Laser-Induced Deep Etching (LIDE). Researchers focused a 1030 nm femtosecond laser (pulse width: 387 fs) through a lens with designed spherical aberration. The pulse energy of the laser was 100 microJoules and the repetition rate was 40 kHz. The lens system comprised a 0.4 NA objective lens and a 50 mm focal-length plano-convex lens. The two lenses’ flat surfaces were separated by 0.1 mm to introduce a longitudinal spherical aberration (LSA) of approximately 1.7 mm. Researchers positioned a fused silica substrate (1 mm thick) in the pre-filament zone located 500 micrometers before the effective focus. Researchers inscribed circular patterns corresponding to the target hole diameters by raster-scanning the substrate in the x-y plane using a 2D stage. The scanning diameters of the micro-holes were 0, 16, 46, 96, and 196 micrometers. Researchers then immersed the laser irradiated glass into a wet etching 8 M potassium hydroxide (KOH) solution at 80 degreesC for 2 hours to selectively remove the laser-modified regions. During etching, sonication was applied using an ultrasonic cleaner set to a frequency of 37 kHz and power of 380 W. The glass was etched along the filament traces, separating into a plate with through-holes and glass rods. The researchers then removed the glass rods and rinsed the glass substrates in deionised water and acetone to remove residual KOH. Researchers coated the faces with a 20 nm layer of gold and then used low voltage, high-resolution scanning electron microscopy (SEM) to acquire top‐view and cross‐sectional images. The sidewall surface roughness was quantitatively measured over a 30 × 30 μm² area using atomic force microscopy (AFM) for pristine glass and the processed samples.
|
- Diameters (in µm) of the micro-holes after fabrication using SEM.
- Sidewall surface roughness over a 30 × 30 μm² area using atomic force microscopy (AFM) operating in non-contact mode.
|
Micro-holes were fabricated in fused silica using Laser-Induced Deep Etching (LIDE). Researchers focused a 1030 nm femtosecond laser through a lens. Researchers inscribed circular patterns corresponding to the target hole diameters by raster-scanning the substrate in the x-y plane using a 2D stage. Researchers immersed the laser irradiated glass into a wet etching 8 M potassium hydroxide (KOH) solution to selectively remove the laser-modified regions. Researchers then took top-view and cross-sectional SEM images of the fabricated micro-holes. Researchers measured the sidewall roughness using atomic force microscopy (AFM) and compared this to the roughness of pristine glass.
Based on the results obtained, how adequate are the micro-holes for ultra-precision optics and photonics?
|
The sidewall formed through the etching process was measured to have a roughness of Ra = 38.1 nm and RMS = 53.1 nm. These values fall short of the few-nanometer requirement for ultra-precision optics and photonics.
|
- Laser-Induced Deep Etching (LIDE) is a laser-based glass processing technique which involves selective internal modification of glass by irradiating high intense laser beam followed by chemical etching.
- Laser filamentation is a nonlinear optical phenomenon that occurs when a laser beam with peak power above the critical power propagates through a medium.
- Filamentation arises from the interplay of several nonlinear effects.
- When these competing effect reach a dynamic balance, the beam undergoes repeated cycles of self-focusing and defocusing, forming a stable plasma channel during propagation.
- Using an aberration-corrected lens, filamentation begins at the point of maximum energy density during propagation, or the beam collapses due to excessive plasma decay, so the target material must be positioned in the maximum energy density zone, making it difficult to avoid over-processing or material damage.
- Using spherical aberration modulates the phase distribution of the laser beam to form thin, uniform, and stable filaments that extend over the millimeter scale before the focal region, so the target material does not need to be located at the point of maximum energy density.
- If thin, uniform, and stable filaments are used, there are fewer issues related to irregular plasma formation and thermal deformation.
|
[{"label":"RBK Item","value":"Laser-Induced Deep Etching (LIDE) is a laser-based glass processing technique which involves selective internal modification of glass by irradiating high intense laser beam followed by chemical etching."},{"label":"Title","value":"Development of Laser-Induced Deep Etching Process for Through Glass Via"},{"label":"URL","value":"https://ieeexplore.ieee.org/document/9081266\n"},{"label":"Date","value":"August 30, 2020"},{"label":"Justification (\"Paywalled\", \"OA\", \"Other (justify)\")","value":"Paywalled, but cited as reference 17 in the paper."},{"label":"RBK Item","value":"Laser filamentation is a nonlinear optical phenomenon that occurs when a laser beam with peak power above the critical power propagates through a medium. "},{"label":"Title","value":"Effect of intensity clamping on laser ablation by intense femtosecond laser pulses"},{"label":"URL","value":"https://opg.optica.org/oe/fulltext.cfm?uri=oe-16-6-3604"},{"label":"Date","value":"March 17, 2008"},{"label":"Justification (\"Paywalled\", \"OA\", \"Other (justify)\")","value":"Open-access, cited as reference 30 in paper."},{"label":"RBK Item","value":"Filamentation arises from the interplay of several nonlinear effects."},{"label":"Title","value":"The propagation of powerful femtosecond laser pulses in opticalmedia: physics, applications, and new challenges. "},{"label":"URL","value":"https://cdnsciencepub.com/doi/10.1139/p05-048"},{"label":"Date","value":"September, 2005"},{"label":"Justification (\"Paywalled\", \"OA\", \"Other (justify)\")","value":"Paywalled, but cited as reference 31 in the paper."},{"label":"RBK Item","value":"When these competing effect reach a dynamic balance, the beam undergoes repeated cycles of self-focusing and defocusing, forming a stable plasma channel during propagation. "},{"label":"Title","value":"Ultrashort filaments of light in weakly-ionized, optically-transparent media"},{"label":"URL","value":"https://arxiv.org/abs/physics/0612063"},{"label":"Date","value":"December 6, 2006"},{"label":"Justification (\"Paywalled\", \"OA\", \"Other (justify)\")","value":"Open-access, cited as reference 32 in the paper."},{"label":"RBK Item","value":"Using an aberration-corrected lens, filamentation begins at the point of maximum energy density during propagation, or the beam collapses due to excessive plasma decay, so the target material must be positioned in the maximum energy density zone, making it difficult to avoid over-processing or material damage."},{"label":"Title","value":"Effect of focusing element-induced aberrations on filamentation and supercontinuum emission in ambient air\n"},{"label":"URL","value":"https://opg.optica.org/oe/fulltext.cfm?uri=oe-29-10-14668"},{"label":"Date","value":"May 10, 2021"},{"label":"Justification (\"Paywalled\", \"OA\", \"Other (justify)\")","value":"Open-access, cited as reference 34 in paper."}]
|
Physics
|
Experimental high-energy
|
Numerical Values
|
First Measurement of the Electron Neutrino Charged-Current Pion Production Cross Section on Carbon with the T2K Near Detector.
|
https://arxiv.org/pdf/2505.00516
|
May 1, 2025.
|
The experiment is conducted by the Tokai to Kamioka (T2K) project, which is a long-baseline neutrino oscillation experiment. T2K long-baseline neutrino beam (peak ~0.6 GeV) from 30 GeV protons at J-PARC; analysis uses ND280 off-axis near detector at 2.5°. The ND280 tracking detector comprises two fine-grained scintillator targets (FGDs; FGD1 predominantly carbon), three time-projection chambers (TPCs) for PID and momentum/charge, and surrounding ECals, all located side a 0.2 T UA1/NOMAD magnet. This analysis uses an exposure of 11.6 × 10²⁰ POT in Forward Horn Current mode; FGD1 fiducial volume excludes the five outermost bars per layer; effective carbon-rich target mass given (FGD1 919.5 kg after FV cuts). νₑ CC interaction producing e⁻ and ≥1 π⁺ that exits the nucleus: νₑA to e⁻π⁺X. Phase-space (ensuring reconstructability): 0.35 < pₑ < 30 GeV/c, cos θₑ > 0.7, p_π < 1.5 GeV/c. Two signal-enriched samples: TPC-π⁺ (pion tracked into downstream TPC) and FGD-π⁺ (contained π⁺ tagged via Michel e⁺ from π⁺ to μ⁺ to e⁺ chain). Use TPC dE/dx PID; Michel-electron clustering for FGD-π⁺; OOFV and ECal-track vetoes to reduce backgrounds, and at the end π⁺ momentum for contained tracks: inferred from distance to Michel-electron.
|
- Differential, flux-integrated cross sections dσ/dx in 8 bins over the restricted phase space, against reconstructed electron momentum (pₑ), electron angle via cos θₑ, and pion momentum (p_π).
- Total flux integrated cross section per target nucleon (carbon dominant FGD1)
- Uncertainty breakdown recorded (detector response, flux, interaction model, target mass; stat vs. syst).
|
In the T2K experiment, using the ND280 near detector with 11.6 × 10²⁰ protons on target and selecting νₑ + C → e⁻ + π⁺ + X interactions within the restricted phase space, which is conducted by the Tokai to Kamioka (T2K) project. Predict what the measured total flux-integrated cross section per target nucleon (in × 10⁻³⁹ cm²) is for these νₑ CC π⁺ events?
|
The measured total flux-integrated cross section per target nucleon is 1.7 - 3.34 × 10⁻³⁹ cm² per nucleon. (The Standard Error is ±0.82 × 10⁻³⁹ cm² per nucleon)
|
- The single pion production (CC1π+) channels contribute ∼10% to the νe appearance signal from the T2K flux, given the current best-fit oscillation parameters.
- A recent measurement of νeCC1π+, which combined T2K data with Super-Kamiokande atmospheric data, revealed an event rate excess localized to low lepton momentum.
|
[{"label":"RBK Item","value":"The single pion production (CC1π+) channels contribute ∼10% to the νe appearance signal from the T2K flux, given the current best-fit oscillation parameters."},{"label":"Title","value":"Measurements of neutrino oscillation parameters from the T2K experiment using 3.6 × 10^{21} protons on target. "},{"label":"URL","value":"https://link.springer.com/article/10.1140/epjc/s10052-023-11819-x"},{"label":"Date","value":"Sep 5, 2023"},{"label":"Justification (\"Paywalled\", \"OA\", \"Other (justify)\")","value":" Paywalled, but this is cited as reference 3 in the paper"},{"label":"RBK Item","value":"A recent measurement of νeCC1π+, which combined T2K data with Super-Kamiokande atmospheric data, revealed an event rate excess localized to low lepton momentum."},{"label":"Title","value":"First Joint Oscillation Analysis of Super-Kamiokande Atmospheric and T2K Accelerator Neutrino Data"},{"label":"URL","value":"https://journals.aps.org/prl/abstract/10.1103/PhysRevLett.134.011801"},{"label":"Date","value":" Jan 2, 2025"},{"label":"Justification (\"Paywalled\", \"OA\", \"Other (justify)\")","value":"Open-access, this is cited as reference 13 in the paper"}]
|
Physics
|
Experimental Condensed Matter Physics.
|
MCQ
|
Listen! it’s a phase transition. The sound of a shape memory alloy
|
https://arxiv.org/abs/2502.18037
|
Jul 31, 2025
|
Researchers evaluated the occurrence of phase transitions (PT) using the sound produced when one hits a nitinol (Ni40Ti50Cu10) sample, by continuously monitoring the sound using an elementary experimental setup. The bar used in the experiment has the following dimensions: (20 ± 0.1) cm long, with an approximate rectangular cross section (0.70 ± 0.05) x (0.60 ±0.05) cm2, and a mass of (50 ±1) g. An additional cylindrical iron bar, (20 ± 0.1) cm long with a diameter of (0.79 ±0.02) cm and a mass of (77 ±1) g was used as a control sample. The bars were immersed in water at 70 °C before being quickly extracted and allowed to cool down to room temperature. While cooling, the bars were quickly and repeatedly hit with a rubber hammer in the middle, perpendicularly to their length, to excite flexural vibrations. A thermocouple was attached to each bar near one node to monitor its temperature. The sound emitted by the bar was recorded with a USB microphone directly connected to a computer’s sound card. The sound spectrum and the frequency of the fundamental mode were measured.
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- The temperature of the bars is read by a multimeter attached to a thermocouple fixed to the bars.
- The fundamental vibration mode frequency of iron and nitinol (NiTiCu) rods upon cooling from 70 °C to 20°C was measured.
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A NiTiCu shape memory alloy rod and an iron (Fe) rod are heated in water at 70 °C and then cooled to room temperature. During the cooling process, both rods are repeatedly struck with a hammer, and their sound spectra are recorded. Which of the following statements about the temperature dependence of the fundamental vibration mode frequency of NiTiCu and Fe is incorrect?
A) The fundamental frequency of the NiTiCu rod drops as the temperature decreases for a specific interval, and outside that interval, it remains the same.
B) The fundamental frequency of the NiTiCu rod rises as the temperature decreases for a specific interval, and outside that interval it remains the same.
C) The fundamental frequency of the NiTiCu rod drops as the temperature decreases for every point in the measured interval.
D) The fundamental frequency of the NiTiCu rod rises as the temperature decreases for every point in the measured interval.
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A) The fundamental frequency of the NiTiCu rod drops as the temperature decreases for a specific interval, and outside that interval, it remains the same.
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- The Ni40Ti50Cu10 alloy exhibits a stable crystal structure at high temperatures, which is cubic austenite, and at low temperatures, the stable phase is the less symmetric monoclinic martensite.
- The temperature-induced austenite/martensite transformation is not isothermal. Upon cooling, the austenite starts transforming into martensite.
- The fundamental frequency depends on the bar’s dimensions (length L and thickness h) and on the Young’s modulus of the material
- Young’s modulus changes as a function of temperature for NiTiCu, which changes the fundamental frequency of the material.
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[{"label":"RBK Item","value":"The Ni40Ti50Cu10 alloy exhibits a stable crystal structure at high temperatures, which is cubic austenite, and at low temperatures, the stable phase is the less symmetric monoclinic martensite."},{"label":"Title","value":"Development and application of a Ni-Ti interatomic potential with high predictive accuracy of the martensitic phase transition. "},{"label":"URL","value":"https://journals.aps.org/prb/abstract/10.1103/PhysRevB.92.134107"},{"label":"Date","value":"Oct 14, 2015"},{"label":"Justification (\"Paywalled\", \"OA\", \"Other (justify)\")","value":"Open-access, this is cited as reference 12 in the paper"},{"label":"RBK Item","value":"The temperature-induced austenite/martensite transformation is not isothermal. Upon cooling, the austenite starts transforming into martensite. "},{"label":"Title","value":"Shape Memory Materials"},{"label":"URL","value":"https://www.cambridge.org/it/universitypress/subjects/engineering/materials-science/shape-memory-materials#gVjol5kZADu6G7fF.97"},{"label":"Date","value":"Oct 1999"},{"label":"Justification (\"Paywalled\", \"OA\", \"Other (justify)\")","value":"Paywalled, but this is cited as reference 18 in the paper"}]
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Physics
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Physics/Condensed Matter Physics
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MCQ
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Hybridization in van der Waals epitaxy of PtSe2/h-BN and PtSe2/graphene heterostructures
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https://arxiv.org/abs/2510.17464
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October 20, 2025
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Researchers investigated monolayer and bilayer PtSe₂ grown on h-BN and graphene substrates via molecular beam epitaxy (MBE) to study substrate-induced hybridization effects.
Growth was performed in a 2-inch MBE reactor using an electron-beam Pt source (Φ(Pt) = 0.003 Å s⁻¹) and a Se cracker source (Φ(Se) = 0.5 Å s⁻¹, 290 °C). Hydrogenated graphene/SiC(0001) substrates with exfoliated h-BN flakes were heated to 320 °C under UHV (~10⁻¹⁰ mbar).
Five Se-Pt co-deposition and annealing cycles produced mono- and bilayer PtSe₂, followed by cooling to 200 °C under Se flux.
Structural quality was confirmed by RHEED and micro-Raman spectroscopy (532 nm, 633 nm lasers), while nano-ARPES (hν = 95 eV, 600 nm spot, 85 K) and ARPES (hν = 90 eV) at SOLEIL synchrotron were used to probe valence band structure and interlayer hybridization.
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- Raman-active modes (E₉, A₁g, LO) measured by a Horiba Raman microscope (532/633 nm lasers) to assess PtSe₂ layer quality.
- Se 3d and Pt 4f core levels were recorded by nano-ARPES/XPS (hν = 95 eV, 600 nm spot, 85 K) to analyze chemical states and charge transfer.
- Band dispersion along Γ–K measured by ARPES (hν = 90 eV, ≤80 µm spot) to determine valence band maxima and hybridization.
- RHEED patterns obtained during MBE growth to confirm epitaxial ordering.
- Substrate temperature (320 °C) and Se/Pt flux ratio (~170:1) controlled for uniform PtSe₂ growth.
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Researchers investigated the Se 3d and Pt 4f core levels of PtSe₂/h-BN and PtSe₂/graphene heterostructures using nano-ARPES/XPS (hν = 95 eV, 600 nm spot, 85 K) to analyze charge transfer effects. What is the value of the shift in the Se 3d core-level binding energy that was observed between PtSe₂/h-BN and PtSe₂/graphene?
A. shift of 0.22 eV
B. shift of 0.15 eV
C. shift of 0.35 eV
D. shift of 0.45 eV
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C. shift of 0.35 eV
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- Understanding the molecular beam epitaxy (MBE) enables precise growth of mono- and bilayer PtSe₂ films on h-BN and graphene substrates under ultra-high vacuum (~10⁻¹⁰ mbar) at 320°C, allowing control of interfacial quality.
- Knowledge of micro-Raman spectroscopy and RHEED diffraction techniques is essential to verify crystal quality, layer thickness, and epitaxial ordering of PtSe₂ during and after growth.
- Background in nano-ARPES/XPS analysis is required to interpret Se 3d and Pt 4f core-level spectra, which reveal chemical states and charge transfer between PtSe₂ and its substrates.
- Understanding of ARPES band mapping helps identify the valence band maxima (VBM) and detect interlayer hybridization effects in PtSe₂/graphene heterostructures.
- Knowledge that a Se 3d binding energy shift indicates a measurable charge transfer difference between PtSe₂/h-BN and PtSe₂/graphene interfaces.
|
[{"label":"RBK Item","value":"Van der Waals (vdW) heterostructures are stacks of two-dimensional materials held together by weak van der Waals forces.\n"},{"label":"Title","value":"Van der Waals heterostructures"},{"label":"URL","value":"https://doi.org/10.1038/nature12385"},{"label":"Date","value":"July 25, 2013"},{"label":"Justification (\"Paywalled\", \"OA\", \"Other (justify)\")","value":"OA"}]
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Physics
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Materials Science
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Free-Format Question
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Surface diffusion of phosphorus on Si(100) after PBr3 adsorption
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https://arxiv.org/abs/2510.15599
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October 17, 2025
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Researchers studied the adsorption of $PBr_3$ gas molecules on top of a B-doped Si(100) substrate (1 Ωcm) at two different substrate temperatures: 77 K and 300 K. The substrate was inserted in an ultra high vacuum (UHV) setup with a base pressure of 5E-11 Torr and prepared by outgassing the wafer at 1170 K overnight in UHV followed by flash-annealing at 1470 K. A scanning tunneling microscope (GPI CRYO, SigmaScan Ltd) was performed by employing mechanically cut Pt-Rh and Pt-Ir tips, as well as polycrystalline W tips that had been electrochemically etched.
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- Experimental empty state STM images (Us = +2.3V, It = 2.0 nA) recorded at 77 K.
- Experimental empty state STM images (Us = +1.5V, It = 2.5 nA) recorded at 300 K.
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Researchers studied the adsorption of $PBr_3$ gas molecule on top of a B-doped Si(100) sample (1 Ωcm) at two different substrate temperatures: 77 K and 300 K. The substrate is inserted in a ultra high vacuum (UHV) setup with a base pressure below 1E-10 mbar and prepared by outgassing the wafer at 1170 K overnight in UHV followed by flash-annealing at 1470 K. The diffusion of the phosphorus atom is studied using a scanning tunneling microscope with mechanically cut Pt-Rh and Pt-Ir tips and electrochemically etched polycrystalline W tips. Researchers acquire STM images at 77 K ($U_s$ = +2.3 V, $I_t$ = 2.0 nA) and 300 K ($U_s$ = +1.5 V, $I_t$ = 2.5 nA). What are the most likely starting or ending position of the P diffusion at 77 K and at 300 K?
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At 77 K, P diffusion mostly started and ended in bridge positions of the Si(100) dimer. At 300 K, P diffuses between end bridge positions.
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- A clean Si(100) surface is characterized by the formation of dimers.
- PBr$_3$ molecule completely dissociates to a single phosphorus atom after adsorption on Si(100) at 300K.
- P atom from PH$_2$ moves along a dimer row between the most favorable end-bridge positions.
|
[{"label":"RBK Item","value":"A clean Si(100) surface is characterized by the formation of dimers."},{"label":"Title","value":"Hydrogen inserted into the Si(100)-2x1-H surface: A first-principles study"},{"label":"URL","value":"https://arxiv.org/abs/2006.16371"},{"label":"Date","value":"June 29, 2020"},{"label":"Justification (\"Paywalled\", \"OA\", \"Other (justify)\")","value":"OA"},{"label":"RBK Item","value":"PBr3 molecule completely dissociates to a single phosphorus atom after adsorption on Si(100) at 300K."},{"label":"Title","value":"PBr3 Adsorption and Dissociation on the Si(100) Surface"},{"label":"URL","value":"https://pubs.acs.org/doi/10.1021/acs.jpcc.3c00421"},{"label":"Date","value":"May 5, 2023"},{"label":"Justification (\"Paywalled\", \"OA\", \"Other (justify)\")","value":"Paywalled, but this is reference 10 in the paper."},{"label":"RBK Item","value":"P atom from PH$_2$ moves along a dimer row between the most favorable end-bridge positions."},{"label":"Title","value":"Reaction paths of phosphine dissociation on silicon (001)"},{"label":"URL","value":"https://doi.org/10.1063/1.4939124"},{"label":"Date","value":"January 7, 2016"},{"label":"Justification (\"Paywalled\", \"OA\", \"Other (justify)\")","value":"Paywalled, but this is reference 1 in the paper."}]
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Physics
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Surface Physics
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Free-Format Question
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Epitaxial growth of gold films on the elemental superconductors V(100), Nb(100) and Nb(110)
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https://arxiv.org/abs/2505.08914
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May 13, 2025
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A V(100) single crystal is inserted in an ultra high vacuum (UHV) system and Ar $^{+}$ sputtered for 20 min with 20 μA ion current. Then, it is degassed at 1000 °C for removing oxidized species due to air contamination. Later, the sample undergoes several cycles of sputtering and annealing, followed by flashes at 1600 °C. This results in the formation of the V(5 × 1)-O reconstruction of the surface. On this surface, Au is deposited in-situ through molecular beam epitaxy with a nominal coverage of 9 ML. The sample is investigated by scanning tunneling microscopy (STM) and X-ray Photoelectron Spectroscopy (XPS) and then undergoes a new annealing at 600 °C. After this last thermal heating , the sample is investigated again through XPS and STM.
STM is acquired in low temperature mode (1.1 K) using a lock-in amplifier with a typical frequency of 980 Hz and oscillation amplitude of 0.1 mV. X-ray photons for XPS come from a non-monochromatic Al Kα photon source (hν = 1486.6 eV).
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- Photoemission spectra on the V 2p energetic region (540-505 eV) as a function of the binding energy [eV] with Al Kα source.
- Photoemission spectra on the Au 4f energetic region (92-80 eV) as a function of the binding energy [eV] with Al Kα source.
- Low Temperature (1.1 K) STM image with atomic resolution.
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Consider the following experiment conducted by researchers: a V(100) single crystal is inserted in an ultra high vacuum (UHV) system and Ar $^{+}$ sputtered for 20 min with 20 μA ion current. Then, it is degassed at 1000 °C for removing oxidized species due to air contamination. Later, the sample undergoes several cycles of sputtering and annealing, followed by flashes at 1600 °C. This results in the formation of the V(5 × 1)-O reconstruction of the surface.
On this surface, researchers deposit a nominal coverage of 9 ML of Au in-situ through molecular beam epitaxy. The sample then undergoes a new annealing at 600 °C and is investigated by scanning tunneling microscopy (STM) and X-ray Photoelectron Spectroscopy (XPS). What can be expected about the quality of the Au films
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Au films become atomically flat, but with clear proof of Au-V intermixing
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- Typical surface reconstructions appear for V(100) presence of large amounts of oxygen in the bulk and the high affinity of V to form stable oxides.
- Au is known for the high miscibility with transition metals.
|
[{"label":"RBK Item","value":"Typical surface reconstructions appear for V(100) presence of large amounts of oxygen in the bulk and the high affinity of V to form stable oxides"},{"label":"Title","value":"Making a noble metal of Pd\n"},{"label":"URL","value":"https://iopscience.iop.org/article/10.1209/epl/i2005-10075-5"},{"label":"Date","value":"June 15, 2005"},{"label":"Justification (\"Paywalled\", \"OA\", \"Other (justify)\")","value":"OA, Cited in the paper as Ref [28]"},{"label":"RBK Item","value":"Au is known for the high miscibility with transition metals."},{"label":"Title","value":"Extreme mixing in nanoscale transition metal alloys"},{"label":"URL","value":"https://www.sciencedirect.com/science/article/pii/S2590238521001752"},{"label":"Date","value":"July 7, 2021"},{"label":"Justification (\"Paywalled\", \"OA\", \"Other (justify)\")","value":"OA"}]
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Physics
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Materials Science, Condensed Matter Physics
|
Free-Format Question
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Incorporating Si into Sb2Se3: Tailoring Optical Phase Change Materials via Nanocomposites
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https://arxiv.org/abs/2510.14990
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October 2, 2025
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Researchers synthesized thin films of antimony selenide (Sb₂Se₃) via magnetron co-sputtering onto 400 μm-thick sapphire substrates under ultrahigh vacuum (base pressure: 2 × 10⁻⁸ Torr) using argon (99.9997%, Airgas) at 4.6 × 10⁻³ Torr. High-purity Si (99.995%) and Sb₂Se₃ (99.999%) targets were co-sputtered using RF powers of 14 W and 17 W, respectively, for 25 minutes to produce films with nominal thicknesses of 30–120 nm. Two compositions were prepared: an undoped Sb₂Se₃ reference and a sample with 20 at.% Si doping, verified by wavelength-dispersive spectroscopy. All films were capped with a 30 nm SiO₂ layer to prevent oxidation. For optical and thermal characterization, samples were either analysed in the as-deposited (amorphous) state or annealed in an N₂ glovebox at 350°C for 20 minutes to achieve full crystallization—particularly required for the 20% Si-doped composition. The same synthesis and capping protocol was applied to both samples to ensure comparability. After that, measured temperature-dependent XRD on two samples: pure Sb2Se3 and 20% Si-doped Sb2Se3. Nano-differential scanning calorimetry, or NanoDSC, which meets industry standards with a sensitivity of 1 Å and a scanning rate of up to 3 × 10^6 K/s, is performed on two samples.
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- Temperature-dependent XRD is done for both undoped and 20% Si-doped Sb₂Se₃.
-Melting temperature measured via nano-differential scanning calorimetry (NanoDSC), for both undoped and 20% Si-doped Sb₂Se₃.
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Antimony selenide (Sb₂Se₃) thin film was synthesized via magnetron co-sputtering onto sapphire substrates under ultrahigh vacuum using argon. High-purity Si and Sb₂Se₃ targets were co-sputtered to produce films with nominal thicknesses of 30–120 nm. Two compositions were prepared: an undoped Sb₂Se₃ reference and a sample with 20 at.% Si doping. All films were capped with a 30 nm SiO₂ layer to prevent oxidation. After that, temperature-dependent XRD measurements were performed on two samples: pure Sb2Se3 and 20% Si-doped Sb2Se3. Additionally, nano-differential scanning calorimetry, or NanoDSC, which meets industry standards, was conducted on both samples. Predict, compared to undoped Sb₂Se₃, does 20% Si-doped Sb₂Se₃ exhibit a higher, lower, or similar transparency window and power consumption?
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Compared to pure Sb₂Se₃, the 20% Si-doped film shows a beneficial increase in the transparency window and reduced power consumption.
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- The undoped Sb₂Se₃ has Tc and Tm as 200°C and 600 °C respectably.
-Si-doped samples are more challenging to crystallize; Si dopants suppress the crystallization of amorphous films, similar to Si-doped Sb2Te3.
|
[{"label":"RBK Item","value":"The undoped Sb₂Se₃ has Tc and Tm as 200°C and 600 °C respectably. "},{"label":"Title","value":"Optical switching beyond a million cycles of low-loss phase change material Sb₂Se₃"},{"label":"URL","value":"https://opg.optica.org/ome/fulltext.cfm?uri=ome-14-1-22"},{"label":"Date","value":"Dec 6, 2023"},{"label":"Justification (\"Paywalled\", \"OA\", \"Other (justify)\")","value":"Open-access, but this is cited as reference 41 in the paper"},{"label":"RBK Item","value":"Si-doped samples are more challenging to crystallize; Si dopants suppress the crystallization of amorphous films, similar to Si-doped Sb2Te3."},{"label":"Title","value":"Phase change behavior improvement of Sb2Te3 films by Si doping: Raman scattering evidence at elevated temperatures"},{"label":"URL","value":"https://pubs.aip.org/aip/adv/article/12/3/035002/2818794/Phase-change-behavior-improvement-of-Sb2Te3-films"},{"label":"Date","value":"Mar 1, 2022"},{"label":"Justification (\"Paywalled\", \"OA\", \"Other (justify)\")","value":"Open-access, but this is cited as reference 43 in the paper"}]
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Physics
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Plasma Physics, Laser Physics
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Numerical Values
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Mass use in 2 μm laser-driven tin plasma using sheet targets
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https://pubs.aip.org/aip/jap/article/138/14/143304/3366875/Mass-use-in-2-m-laser-driven-tin-plasma-using
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October 8, 2025
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The researcher demonstrates the mass-use efficiency of a 2-μm-wavelength laser-produced plasma. In a vacuum chamber maintained at ~ 10^-6 mbar, they stream droplets of liquid tin through a nozzle. The diameter of the tin droplets can be varied by controlling the volumetric flow rate in tandem with applying a suitable modulation to the nozzle. The resulting liquid stream is broken into droplets of consistent diameter. First, a low-energy, 1 μm wavelength prepulse laser is fired onto a tin droplet to produce thin sheet targets of tin. After the predetermined delay, a spatially and temporally flat-top 2 μm laser beam with an energy enclosed within the FWHM of the spatial profile, E_encl of 75%, is fired onto the tin sheet, generating the plasma. The generated tin plasma is studied using four calibrated EUV photodiodes placed at angles of 30 °, 41°, 64°, and 114° with respect to the direction opposite to the laser light propagation. Additionally, place two fast EUV photodiodes at angles of 21° (forward) and 159° (backward) with respect to the direction opposite to the laser light propagation. The EUV-emitting surface is captured using the EUV imaging system, which is placed at 90° with respect to the direction opposite to the laser light propagation. The main-pulse laser, which has a flat spatial profile, is measured before the pulse is directed into the vacuum chamber and is corrected for transmission through the vacuum window. The 2μm-wavelength drive laser characteristics are maintained at an 11ns time duration and an intensity of 7 x 10^10 W/cm^2. Then, the conversion efficiency (CE) of laser light into EUV light is studied as a function of the target diameter and as a function of overlap volume with the main-pulse laser.
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- Conversion efficiency (CE) (in %) studied as a function of the target diameter at an intensity of 7 x 10^10 W/cm^2 with a 11ns time duration.
- Conversion efficiency (CE) (in %) studied as a function of overlap volume at an intensity of 7 x 10^10 W/cm^2 of 11ns time duration.
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The researcher demonstrates the mass-use efficiency of a 2-μm-wavelength laser-produced plasma. In a vacuum chamber maintained at ~ 10^-6 mbar, they stream droplets of liquid tin through a nozzle. The diameter of the tin droplets can be varied by controlling the volumetric flow rate in tandem with applying a suitable modulation to the nozzle. The 2μm-wavelength drive laser characteristics are maintained at an 11ns time duration and an intensity of 7 x 10^10 W/cm^2. Then, the conversion efficiency (CE) of laser light into EUV light is studied as a function of the target diameter and as a function of overlap volume with the main-pulse laser. Predict what the optimum overlap volume, which is the volume at which plasmas start to show near-peak CE (plateau) (in m^3)?
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The volume at which plasmas start to show near-peak CE (plateau) is around 1.7 x 10^-15 - 2.3 x 10^-15 m^3. (No CI/SE/SD is given, fallback is 0.3 x 10^-15 m^3)
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- After the pre-pulse laser impact the sheet is propelled in the direction of the beam and the sheet retracts due to the surface tension of the liquid
- Late-time sheets may have the same diameter as early-time sheets, but will be thinner due to the continuous mass loss during the expansion, and retraction processes.
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[{"label":"RBK Item","value":"After the pre-pulse laser impact the sheet is propelled in the direction of the beam and the sheet retracts due to the surface tension of the liquid "},{"label":"Title","value":"Mass Loss from a Stretching Semitransparent Sheet of Liquid Tin"},{"label":"URL","value":"https://journals.aps.org/prapplied/abstract/10.1103/PhysRevApplied.13.024035"},{"label":"Date","value":"February 13, 2020"},{"label":"Justification (\"Paywalled\", \"OA\", \"Other (justify)\")","value":"Open-access, this is cited as reference 14 in the paper"},{"label":"RBK Item","value":"Late-time sheets may have the same diameter as early-time sheets, but will be thinner due to the continuous mass loss during the expansion, and retraction processes."},{"label":"Title","value":"Mass Partitioning in Fragmenting Tin Sheets"},{"label":"URL","value":"https://journals.aps.org/prapplied/abstract/10.1103/PhysRevApplied.20.014048"},{"label":"Date","value":"July 21, 2023"},{"label":"Justification (\"Paywalled\", \"OA\", \"Other (justify)\")","value":"Open-access, this is cited as reference 17 in the paper"}]
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Physics
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Materials and surface science
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Numerical Values
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The Impact of Gas Cluster Ion Beam Sputtering on the Chemical and Electronic Structure of Methyl Ammonium Lead Iodide Thin Films
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https://advanced.onlinelibrary.wiley.com/doi/10.1002/admi.202500102
|
May 23, 2025
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The perovskite precursor solution prepares the thin film methylammonium lead iodide (MAPbI₃) for film fabrication was prepared under nitrogen atmosphere by dissolving 159 mg methylammonium iodide (MAI) (Dyenamo AB, 99.99% purity on trace elements basis) and 461 mg PbI2 (Tokyo Chemical Industry 99.99% purity in trace metals basis, >98.0% total purity) in 71 μL dimethyl sulfoxide (DMSO, Sigma-Aldrich, ≥99.9% purity, anhydrous) and 0.6 mL of N, N dimethylformamide (DMF, Sigma-Aldrich, 99.8% purity, anhydrous) by mixing for ≈12 h. As substrates, we utilized quartz glass coated with indium tin oxide (ITO), which was cleaned for 10 minutes each in an ultrasonic bath with isopropanol and ethanol. After drying the substrate with N2 gas and exposing each to (UV)-ozone for 15 min, the samples were directly introduced into a nitrogen-filled glove box for perovskite deposition. The MAPbI3 thin films were fabricated by spin-coating 40 μL of the precursor solution for 30 s at 4000 rpm on the cleaned ITO. After 10 s in the spin-coating process, 200 μL of ethyl acetate (EA, Sigma-Aldrich, 99.8% purity, anhydrous) was introduced on top of the film as the anti-solvent. Crystallization was induced by annealing the sample for 3 minutes at 100 °C. For the fabrication of a PbI2 reference film, 461 mg of PbI2 was dissolved in 1 mL DMF and mixed for ≈12 h. The solution was then heated at 80 °C for 2 h, and while still hot, spin-coated for 30 s at 6000 rpm onto an ITO sample that had been cleaned as described above. All solutions were prepared one day before each film preparation and measurement. While the samples were prepared in a glove box with a nitrogen atmosphere, they were briefly exposed to ambient air (5 min) before being introduced into the photoemission system. The methylammonium lead iodide (MAPbI₃) thin films are exposed to argon gas cluster ion beam (GCIB) sputtering under two kinetic energy conditions: 3.2 and 1.5 eV per Ar atom (eV/Ar). For depth-profiling (long-term exposure), samples were sputtered for 1, 13, 16, and 32 hours at both energies. For surface cleaning (short-term exposure), samples were sputtered for 10, 30, and 60 minutes using only the 1.5 eV/Ar condition. A pristine (unsputtered) MAPbI₃ sample and a separately prepared PbI₂ reference film were included as controls. All photoemission measurements were conducted under ultrahigh vacuum (UHV) conditions and at room temperature using a hemispherical analyzer (EA15) with a microchannel plate (PREVAC). The UHV system is equipped with a monochromatic He I source with photon energy h𝜈 = 21.22 eV, and a monochromatic Al K𝛼 x-ray source with h𝜈 = 1486.6 eV. Measurements of the SECO were performed with the application of a – 10.0 V sample bias. The calibration of the photoemission system was performed by setting the Au Fermi edge for UPS and the Au 4f7/2 peak for XPS of a clean single-crystal Au(111) to 0 eV and 84 eV binding energies, respectively. Gas cluster ion beam sputtering was performed using the GCIB 10S (Ionoptika), which allows for the adjustment of cluster size and energy selection. Here, two settings for achieving the lowest energy per argon atom Ekin/n (≈3000 Ar atoms with an acceleration voltage of 5 and 10 kV, respectively) were utilized with the maximal sputter area of 67.1 mm2.
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- Work function shift is measured using ultraviolet photoelectron spectroscopy (UPS) on the surface of the MAPbI₃ after 16 hours of GCIB sputtering at 3.2 eV/Ar.
|
The perovskite precursor solution, which prepares the thin film methylammonium lead iodide (MAPbI₃) for film fabrication, was prepared under a nitrogen atmosphere by dissolving 159 mg methylammonium iodide and 461 mg PbI2 in 71 μL dimethyl sulfoxide and 0.6 mL of N, N-dimethylformamide by mixing for ≈12 h. The MAPbI3 thin films were fabricated by spin-coating 40 μL of the precursor solution for 30 s at 4000 rpm on the cleaned ITO. For the fabrication of a PbI2 reference film, 461 mg of PbI2 was dissolved in 1 mL DMF and mixed for ≈12 h. The solution was then heated at 80 °C for 2 h, and while still hot, spin-coated for 30 s at 6000 rpm onto an ITO sample that had been cleaned as described above. The methylammonium lead iodide (MAPbI₃) thin films are exposed to an argon gas cluster ion beam (GCIB) sputtering with a kinetic energy of 3.2 eV/Ar atom. For depth-profiling (long-term exposure), samples were sputtered for 16 hours. A pristine (unsputtered) MAPbI₃ sample and a separately prepared PbI₂ reference film were included as controls. All photoemission measurements were conducted under ultrahigh vacuum (UHV) conditions and at room temperature. The calibration of the photoemission system was performed by setting the Au Fermi edge for ultraviolet photoelectron spectroscopy (UPS). Predict the work function shift (ΔWF) for this condition (in eV ).
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The work function shift (ΔWF) of MAPbI₃ thin film after 16 hours of GCIB sputtering at 3.2 eV/Ar is 0.8 - 1.2 eV. (No CI/SE/SD is mentioned, the fallback is ±0.1 eV)
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- Upon illumination, PbI2 decomposes into Pb0 and gaseous I2 due to photolysis. Using 3.2 eV/Ar, we observed a complete loss of carbon and nitrogen on the surface after 1 h of sputtering, in agreement with the emergence of the Pb0 core level.
- From the first hour and up to 16 h of sputtering, MAPbI3 gradually degrades into PbI2 and metallic Pb while the valence band still represents the perovskite feature, indicating a partial degradation on the surface.
- Continued sputtering after 16 h drastically changed the surface composition, where the metallic Pb dominates on the surface, and the valence band differs significantly from the perovskite valence structure.
|
[{"label":"RBK Item","value":"Upon illumination, PbI2 decomposes into Pb0 and gaseous I2 due to photolysis. Using 3.2 eV/Ar, we observed a complete loss of carbon and nitrogen on the surface after 1 h of sputtering, in agreement with the emergence of the Pb0 core level. "},{"label":"Title","value":"Photoinduced degradation of methylammonium lead triiodide perovskite semiconductors"},{"label":"URL","value":"https://pubs.rsc.org/en/content/articlelanding/2016/ta/c6ta06497c"},{"label":"Date","value":"Sep 22, 2016"},{"label":"Justification (\"Paywalled\", \"OA\", \"Other (justify)\")","value":"Paywalled, but this is cited as reference 36 in the pape"}]
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Physics
|
Material science
|
MCQ
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Soft Conductive Textile Sensors: Characterization Methodology and Behavioral Analysis
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https://www.mdpi.com/1424-8220/25/14/4448
|
July 17, 2025
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Researchers characterized a soft conductive textile sensor in terms of its stability. The sensor was obtained by combining a soft silicone substrate and a conductive fabric. Both the soft silicone structure and the conductive fabric shape were designed in accordance with the ISO Standard 37:2017; specifically, the sensor was designed with a dog-bone or dumbbell shape. The conductive fabric was a Stretch Conductive Fabric from LESS EMF, which is a 76% Nylon and 24% elastic fabric with a silver-plating. The fabric had fibers with a 12.7µm diameter. The monoaxile strain testing was performed on an Instron tester, and the resistance was measured with a Wheatstone bridge and an NI USB 6009 DAQ Card from National Instruments. The sensor was tested at strain levels of 25%, 50%, 75%, and 100% and kept at each strain level for 30s.
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- Mechanical strain
- Electrical resistance
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Researcher studied the performance of a textile sensor made from a soft silicone substrate and a conductive fabric containing 76% Nylon and 24% elastic fabric with a silver-plating. This 12.7µm diameter sensor was tested for its stability on four different strain levels, namely 25%, 50%, 75% and 100%. Which of these options best describes the relative change in resistance, which is the delta change in resistance from initial resistance, divided by initial resistance?
A. The relative change in resistance increases with strain.
B. The relative change in resistance is constant at the four strain levels.
C. The relative change in resistance decreases with strain.
D. The relative change in resistance increases from 25% to 75% but decreases below the 50% value at 100%.
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C. The relative change in resistance decreases with strain.
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- Conductive textiles can be used to realize resistive stretching sensors, which are characterized by a change in electrical resistance as a function of the applied mechanical strain.
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Physics
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Physics/Applied Physics
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MCQ
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Experimental Characterization and Dynamic Modeling of THz Channels Under Fog Conditions
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https://arxiv.org/abs/2510.09906
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October 10, 2025
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Researchers experimentally emulated a THz line-of-sight (LoS) channel transmitting through fog using a controlled environment via a fog chamber. From the transmitter side, a Ceyear 1465D signal generator produced a base signal (100 kHz to 20 GHz), which was then subjected to a Ceyear 82406D ×18 frequency multiplier to achieve the target THz frequencies of 220 GHz and 320 GHz. The radiated signal was launched using a Ceyear 89901S horn antenna integrated with a 10-cm dielectric lens, yielding a gain of up to 33 dBi at 220 GHz and a beam width of ~4º. For a symmetric channel, the receiver employed an identical horn-lens assembly. A Ceyear 71718 power sensor was used on the receiver side, with measurements sampled at 5 Hz. Both antennas were mounted at 85 cm to eliminate ground effects of the Fresnel zone. Power loss was monitored as a function of time. A purpose-built chamber with inner dimensions of 1.0×0.5×0.5 m$^3$ (in L×W×H) served as the propagation medium. Circular apertures (90 mm in diameter) on chamber walls allowed unobstructed channel propagation. Dense fog was created by a commercial ultrasonic generator, which generated water droplets with diameters ranging from 1 to 30 μ. The output was fed into the chamber through flexible tubing and controlled airflow to maintain a quasi-stationary state of fog necessary for robust small-scale statistical analysis. The temperature was maintained at around 24 $^{\circ}$C and the relative humidity during fog trials was up to 92.2% RH.
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- Signal-to-noise ratio statistics (from 16.2 to 17.1 dB) for the 220 and 320 GHz signals
- Power loss of the THz signals as a function of time up to 250 s
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The terahertz (THz) band is a promising candidate for sixth-generation wireless networks, but its deployment in outdoor environments is challenged by meteorological phenomena such as fog, which imposes variable and difficult-to-predict channel degradation. Terahertz signals (220 GHz and 320 GHz) were allowed to propagate in a controlled fog chamber at 24 $^{\circ}$C and relative humidity of up to 92.2% RH. Which of the following outcomes are observed? Mark all the correct options.
A. The presented environmental conditions cause power loss to be scatter-dominated.
B. The Rician distribution provides an excellent fit to the measured SNR statistics across the entire probability range, outperforming the Weibull model.
C. The fog-induced power loss is dominated by absorption components.
D. The cumulative distribution function of the SNR fits better with the Weibull model at 220 GHz than at 320 GHz.
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B. The Rician distribution provides an excellent fit to the measured SNR statistics across the entire probability range, outperforming the Weibull model.
C. The fog-induced power loss is dominated by absorption components rather than scattering.
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- Fog introduces significant and time-variable extinction losses to THz radiation.
- The Rician model can be used as the cumulative distribution function to model the signal-to-noise ratio for a line-of-sight dominated channel.
- Fog and other high humidity environments degrade radiated THz signals mainly due to water droplets absorption rather than scattering or scintillation.
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[{"label":"RBK Item","value":"Fog introduces significant and time-variable extinction losses to THz radiation."},{"label":"Title","value":"Review of weather impact on outdoor terahertz wireless communication links"},{"label":"URL","value":"https://doi.org/10.1016/j.nancom.2016.07.006"},{"label":"Date","value":"October 5, 2016"},{"label":"Justification (\"Paywalled\", \"OA\", \"Other (justify)\")","value":"Open access; this is reference 7 in the manuscript."},{"label":"RBK Item","value":"The Rician model can be used as the cumulative distribution function to model the signal-to-noise ratio for a line-of-sight dominated channel."},{"label":"Title","value":"Impact of Snowfall on Terahertz Channel Performance: Measurement and Modeling Insights"},{"label":"URL","value":"https://ieeexplore.ieee.org/abstract/document/10568390"},{"label":"Date","value":"June 21, 2024"},{"label":"Justification (\"Paywalled\", \"OA\", \"Other (justify)\")","value":"Paywalled, but this is reference 24 in the paper."},{"label":"RBK Item","value":"Fog and other high humidity environments degrade radiated THz signals mainly due to water droplets absorption rather than scattering or scintillation."},{"label":"Title","value":"Experimental comparison of performance degradation from terahertz and infrared wireless links in fog"},{"label":"URL","value":"https://opg.optica.org/josaa/abstract.cfm?uri=josaa-29-2-179"},{"label":"Date","value":"November 14, 2011"},{"label":"Justification (\"Paywalled\", \"OA\", \"Other (justify)\")","value":"Paywalled, but this is reference 23 in the paper."}]
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Physics
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Nuclear Physics
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MCQ
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High-precision Penning trap mass measurements of neutron-rich chlorine isotopes at the N = 28 shell closure
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https://arxiv.org/abs/2505.18354
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May 23, 2025
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The researchers performed the first high-precision mass measurements of the neutron-rich isotopes 43–45Cl using the Time-of-Flight Ion Cyclotron Resonance (TOF-ICR) technique at the Low Energy Beam and Ion Trap (LEBIT) facility, which is coupled to the National Superconducting Cyclotron Laboratory (NSCL). A 48Ca primary beam was accelerated to 140 MeV/u and impinged on a 9Be target of thickness 846 mg/cm2. The produced fragments were sent through the A1900 fragment separator, where the 43−45Cl isotopes were identified at the focal plane via the energy loss and time-of-flight (∆E vs TOF) PID method and selected. After the separation, the beam proceeded via a momentum compression beamline to the gas stopping area. Before entering a gas cell, the beam was slowed with aluminum degraders and dispersion matched with an aluminum wedge. The effective thicknesses of the rotatable degraders were adjusted, allowing the beam to enter the gas cell at an energy of less than 1 MeV. The gas stopping area utilizes two gas cells, the Room Temperature Gas Cell (RTGC) and the Advanced Cryogenic Gas Cell (ACGS). In the RTGC or ACGS, the highly charged ions undergo collisions with the helium gas and the chlorine isotopes. In the RTGC, ions are transported by a combination of radiofrequency (RF) and direct current (DC) fields, as well as gas flow. In the ACGS, ions are transported via ion carpet surfing using an RF electric wave and a DC push field. In both gas cells, the ions are then extracted into an RF quadrupole (RFQ) ion guide. The gas stopping and LEBIT facilities are raised to 30 kV while the transport beam line between them is at ground potential. During transport, the ions are sent through a dipole magnet with a resolving power of approximately 1500. After entering LEBIT, the selected continuous beam was injected into a linear buffer-gas-filled Paul trap, which serves as both a cooler and a buncher. Following extraction, the ion bunches are guided and injected into the 9.4 T Penning trap mass spectrometer. Ions in the Penning trap are confined radially via a homogeneous magnetic field B and axially via a quadrupolar electrostatic field. The Time-of-Flight is measured with a Multi-Channel Plate (MCP) detector. Seven independent measurements with tRF = 100 ms were made of 43Cl+ using 39K+ as the reference, of which the final three utilized the pulsed Ramsey resonance technique. Seven independent measurements with tRF = 50 ms were made of 44Cl+, using [12C14N1H216O]+ (A = 44) and 39K+ as references. Four independent measurements with tRF = 100 ms of 45Cl+ were made using [28Si16O1H]+ (A = 45) as the reference ion.
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- 7 independent measurements for Time-of-Flight (in μm) with tRF = 100 ms were made of 43Cl+ using 39K+ as the reference.
- 7 independent measurements for Time-of-Flight (in μm) with tRF = 50 ms were made of 43Cl+ using [12C14N1H216O]+ and 39K+ as the reference.
- 4 independent measurements for Time-of-Flight (in μm) with tRF = 100 ms were made of 43Cl+ using [28Si16O1H]+ as the reference.
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High-precision mass measurements are done for the neutron-rich isotopes 43–45Cl using the Time-of-Flight Ion Cyclotron Resonance (TOF-ICR) technique at the Low Energy Beam and Ion Trap (LEBIT) facility. A 48Ca primary beam was accelerated and impinged on a 9Be target. After this, the beam proceeded via a momentum compression beamline to the gas stopping area. The gas stopping area utilizes two gas cells, the Room Temperature Gas Cell (RTGC) and the Advanced Cryogenic Gas Cell (ACGS). During transport, the ions are sent through a dipole magnet. After entering LEBIT, the selected continuous beam was injected into a linear buffer-gas-filled Paul trap, which serves as both a cooler and a buncher. Following extraction, the ion bunches are guided and injected into the 9.4 T Penning trap mass spectrometer. The Time-of-Flight is measured with a Multi-Channel Plate (MCP) detector. For all measurements, reference ion measurements are interleaved with those of the ion of interest to obtain a linearly interpolated value of B at the time the ion of interest is measured. Predict which statement is correct according to this experimental setup.
a) The systematic shifts in mean frequency ratio scale linearly with this mass difference, which is over an order of magnitude higher than the statistical uncertainty.
b) The systematic shifts in mean frequency ratio scale linearly with this mass difference, which is over an order of magnitude smaller than the statistical uncertainty.
c) The systematic shifts in mean frequency ratio scale linearly with this mass difference, which is over multiple orders of magnitude smaller than the statistical uncertainty.
d) The systematic shifts in mean frequency ratio scale linearly with this mass difference, which is over a multiple order of magnitude higher than the statistical uncertainty.
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b) The systematic shifts in mean frequency ratio scale linearly with this mass difference, which is over an order of magnitude smaller than the statistical uncertainty.
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- Precision mass measurements in this region of the nuclear chart are highly desirable to fully characterize the strength of the shell closure.
- Isobaric contamination was mitigated using a dipolar RF excitation applied to the central ring electrode near their respective reduced cyclotron frequencies.
|
[{"label":"RBK Item","value":"Precision mass measurements in this region of the nuclear chart are highly desirable to fully characterize the strength of the shell closure."},{"label":"Title","value":"Shape Coexistence and the 𝑁 = 28 Shell Closure Far from Stability"},{"label":"URL","value":"https://journals.aps.org/prl/abstract/10.1103/PhysRevLett.84.5062"},{"label":"Date","value":"May 29, 2000"},{"label":"Justification (\"Paywalled\", \"OA\", \"Other (justify)\")","value":"Paywalled, but this is cited as reference 34 in the paper"},{"label":"RBK Item","value":"Isobaric contamination was mitigated using a dipolar RF excitation applied to the central ring electrode near their respective reduced cyclotron frequencies."},{"label":"Title","value":"Population inversion of nuclear states by a Penning trap mass spectrometer"},{"label":"URL","value":"https://iopscience.iop.org/article/10.1209/epl/i2004-10089-5"},{"label":"Date","value":"June 2, 2004"},{"label":"Justification (\"Paywalled\", \"OA\", \"Other (justify)\")","value":"Paywalled, but this is cited as reference 53 in the paper"}]
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Physics
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Experimental Quantum Physics
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Free-Format Question
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Quantum light drives electrons strongly at metal needle tips
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https://www.nature.com/articles/s41567-025-03087-1
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Nov 7, 2025
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In the experiment, temporally and spatially single-mode bright squeezed vacuum (BSV) is generated from an unseeded optical parametric amplifier. The BSV is centred at 1,600 nm (photon energy of 0.77 eV) and has a pulse duration of 25 fs. The repetition rate of the pump laser is 1 kHz. The experiment is conducted with a range of mean pulse energies of BSV, from 3.2 nJ to 17.0 nJ. The adjustment of the mean pulse energy is done by varying the pulse energy of the optical parametric amplifier pump. To pick off a small percentage of each BSV pulse by a fused silica window reflection to monitor the pulse-to-pulse photon number fluctuations using a photodiode. The BSV pulses are sent into an ultrahigh vacuum chamber with a base pressure of p < 1 × 10−8 hPa, where they are focused to 8 μm (1/e2 intensity radius) using an off-axis parabolic mirror. A metal needle tip with a radius of a few tens of nanometres is situated on a three-axis nanopositioner, with which we align the tip apex to the optical focus. After the photoemission from the negatively biased tip (V = −310 V), the electrons travel towards a home-built low-energy spectrometer, which measures both the number of electrons (up to a few tens per shot) and each electron's energy from -20 eV to +60 eV for each laser pulse with an energy resolution of ~2 eV. The electron spectrometer is based on an electrostatic cylindrical deflector analyser. A microchannel plate equipped with a phosphor screen is used to image individual electrons with a camera. This camera and the photodiode in front of the vacuum chamber are synchronized to the laser's repetition rate, allowing us to correlate the photon number with the number and energy of the electrons for each light pulse. For each electron spectrum at a fixed BSV mean power, the final measurement is recorded by accumulating 10,000 images, each containing electrons from ~13 laser pulses per image.
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- The number of electrons is measured for each electron's energy from -20 eV to +60 eV at mean pulse energies of 3.2 nJ.
- The number of electrons is measured for each electron's energy from -20 eV to +60 eV at mean pulse energies of 5.3 nJ.
- The number of electrons is measured for each electron's energy from -20 eV to +60 eV at mean pulse energies of 7.3 nJ.
- The number of electrons is measured for each electron's energy from -20 eV to +60 eV at mean pulse energies of 10.2 nJ.
- The number of electrons is measured for each electron's energy from -20 eV to +60 eV at mean pulse energies of 14 nJ.
- The number of electrons is measured for each electron's energy from -20 eV to +60 eV at mean pulse energies of 17 nJ.
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In the experiment, temporally and spatially single-mode bright squeezed vacuum (BSV) is generated from an unseeded optical parametric amplifier. The experiment is conducted with a range of mean pulse energies of BSV, from 3.2 nJ to 17.0 nJ. A metal needle tip with a radius of a few tens of nanometres is situated on a three-axis nanopositioner, with which we align the tip apex to the optical focus. After photoemission from the negatively biased tip, the electrons travel towards a low-energy spectrometer, which measures both the number of electrons and the energy of each electron, ranging from -20 eV to +60 eV, for each laser pulse. After measuring electron energy spectra driven by BSV with increasing mean pulse energy, as mentioned in this experiment, is a plateau or cut-off observed, and if so, what type of cut-off is it?
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Neither a plateau nor a cut-off is observed for this experiment with these given parameters.
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- According to the three-step model of strong-field physics, electrons tunnel-emitted into an intense optical field can be driven back to the parent matter.
- Recent studies show quantum correlations between non-perturbative harmonics and predict non-Gaussian states of harmonics and entanglement between harmonics.
- BSV was used to generate high harmonics in solids. Most recently, a two-colour gas-phase high-harmonic generation (HHG) experiment showed in situ quantum state tomography.
|
[{"label":"RBK Item","value":"According to the three-step model of strong-field physics, electrons tunnel-emitted into an intense optical field can be driven back to the parent matter."},{"label":"Title","value":"Plasma perspective on strong field multiphoton ionization"},{"label":"URL","value":"https://journals.aps.org/prl/abstract/10.1103/PhysRevLett.71.1994"},{"label":"Date","value":"Sep 27, 1993"},{"label":"Justification (\"Paywalled\", \"OA\", \"Other (justify)\")","value":"Paywalled, but this is cited as reference 16 in the paper"},{"label":"RBK Item","value":"Recent studies show quantum correlations between non-perturbative harmonics and predict non-Gaussian states of harmonics and entanglement between harmonics."},{"label":"Title","value":"Generation of Massively Entangled Bright States of Light during Harmonic Generation in Resonant Media"},{"label":"URL","value":"https://journals.aps.org/prx/abstract/10.1103/PhysRevX.15.011023"},{"label":"Date","value":"Feb 5, 2025"},{"label":"Justification (\"Paywalled\", \"OA\", \"Other (justify)\")","value":"Open-access, this is cited as reference 28 in the paper"},{"label":"RBK Item","value":"BSV was used to generate high harmonics in solids. Most recently, a two-colour gas-phase high-harmonic generation (HHG) experiment showed in situ quantum state tomography."},{"label":"Title","value":"Measuring and controlling the birth of quantum attosecond pulses"},{"label":"URL","value":"https://journals.aps.org/prx/abstract/10.1103/PhysRevX.15.011023"},{"label":"Date","value":"Feb 13 2025"},{"label":"Justification (\"Paywalled\", \"OA\", \"Other (justify)\")","value":"Open-access, this is cited as reference 41 in the paper"}]
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Physics
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Physics / Instrumentation and Detectors
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Numerical Values
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Low-temperature Performance of Gd₃(Ga,Al)₅O₁₂:Ce Scintillators
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https://arxiv.org/abs/2508.13844v2
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October 22, 2025
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To study the effect of temperature on GAGG:Ce, researches used two different GAGG crystal dimensions (GRAPE: 12 x 12 x 12 mm2; POLAR-2: 6 x 6 x 20 mm3) and placed each in a cryostat (Bluefors LD 250) with a photo-multiplier tube (PMT) (Hamamatsu R1924A; stable within ~1 K) coupled and sealed to the cryostat window for analysis. The GAGG was illuminated with a 22Na source (10.8 MBq) placed at 0.7 m distance in an external collimated lead enclosure, which also resulted in back-to-back 511 keV gamma-ray emission. A secondary PMT coupled to a plastic scintillator (12 x 12 x 12 mm2; balanced aluminum-gadolinium ratio) equidistant and opposite from the GAGG source was used in conjunction with the primary PMT to create a coincidence signal (5 μs period; 0.5 GHz sampling rate). An oscilloscope then analyzed the output signal as a function of time (ns) at different temperatures ranging. The cryostat was cooled to 15 mK after 2 days of cooling and slowly warmed to room temperature over 1.5 days.
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- Summed signal (arb. units) from both PMTs as a function of time (ns)
- Temperature (K) of GAGG:Ce crystals for GRAPE and POLAR-2 configurations.
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To study the effect of temperature on GAGG:Ce, researchers illuminated two different GAGG crystals with a 22Na source. The light yield was measured by counting the number of photoelectrons produced from the scintillation pulses, which was obtained by dividing the height of each pulse by the mean pulse height and rounding up to the nearest integer. The mean pulse height was in turn estimated by fitting the pulse height spectrum sampled at room temperature at different light intensities. The temperatures studies ranged from 15 mK to room temperature. Using the described experimental setup with the POLAR-2 crystal, at what predicted percentage does the light yield end up plateauing as the temperature approaches the bottom limit, relative to the room temperature yield?
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Light Yield = [75-85] pp. Note: No CI/SE/SD reported → fallback ±5 pp applied.
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- GAGG:Ce has the significant advantage that it is non-hygroscopic and that it shows little performance degradation after irradiation when compared to scintillators with similar light yields.
- Previous studies have shown that the scintillation decay time increases by 20% when cooling GAGG:Ce from room temperature to 250 K, while the light yield increases only by several percent.
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[{"label":"RBK Item","value":"GAGG:Ce has the significant advantage that it is non-hygroscopic and that it shows little performance degradation after irradiation when compared to scintillators with similar light yields."},{"label":"Title","value":"Evaluation of GAGG:Ce scintillators for future space applications"},{"label":"URL","value":"https://doi.org/10.1088/1748-0221/13/02/P02023"},{"label":"Date","value":"Feb 21, 2018"},{"label":"Justification (\"Paywalled\", \"OA\", \"Other (justify)\")","value":"Paywalled, but included as reference 21 in the main paper."},{"label":"RBK Item","value":"Previous studies have shown that the scintillation decay time increases by 20% when cooling GAGG:Ce from room temperature to 250 K, while the light yield increases only by several percent."},{"label":"Title","value":"Evaluation of GAGG:Ce scintillators for future space applications"},{"label":"URL","value":"https://doi.org/10.1088/1748-0221/13/02/P02023"},{"label":"Date","value":"Feb 21, 2018"},{"label":"Justification (\"Paywalled\", \"OA\", \"Other (justify)\")","value":"Paywalled, but included as reference 21 in the main paper. This is the same reference as the previous RBK item."}]
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Physics
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Physics/Materials and Magnetism
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Numerical Values
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Reconfigurable All-Nitride Magneto-Ionics
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https://pubs.acs.org/doi/full/10.1021/acsnano.5c04013
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May 7, 2025
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Researchers deposited MnNₓ(15 nm)/Ta(10 nm) bilayers onto thermally oxidized Si/SiO₂ substrates by DC reactive sputtering, forming a 5 nm Mn₃N₂ seed layer and a 10 nm Mn layer grown at nitrogen partial pressure Pₙ = 6%. The top electrical contact was made to the Ta layer, and the bottom to the p-type Si substrate. A +30 V bias was applied for 1 h at room temperature to induce nitrogen migration from MnNₓ into Ta (voltage-conditioned, VC state). Magnetic hysteresis loops of the same sample were measured at 5 K using SQUID magnetometry after +2 T field-cooling from 300 and 380 K to obtain the saturation magnetization (Mₛ), before (as-grown, AG) and after voltage conditioning (VC).
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• Saturation magnetization (Mₛ) measured at 5 K using SQUID magnetometry for the as-grown (AG) state and a voltage-conditioned (VC) state gated with +30 V for 1 h at room temperature.
• Magnetic hysteresis loops measured after +2 T field-cooling from 300 K and 380 K.
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MnNₓ(15 nm)/Ta(10 nm) bilayers were fabricated on Si/SiO₂ substrates by DC reactive sputtering, consisting of a 5 nm Mn₃N₂ seed layer and a 10 nm Mn top layer deposited under a nitrogen partial pressure of 6% (as-grown, AG). A +30 V bias was then applied for 1 h at room temperature to drive nitrogen migration from the MnNₓ layer into the Ta overlayer (voltage-conditioned, VC). Magnetic hysteresis loops were measured on the same sample at 5 K using SQUID magnetometry after +2 T field-cooling from 300 and 380 K.
Under these conditions, what is the percentage increase in the saturation magnetization (Mₛ) in the VC state relative to the AG state?
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ΔMₛ = 23 % ± 5 pp (18–28 %) increase.
Note: No CI/SE/SD reported -> a ±5 pp fallback was applied.
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• Magneto-ionics (voltage-driven nitrogen motion): Application of an electric field drives nitrogen ions between MnNₓ and the adjacent Ta layer, reversibly altering the magnetic properties such as Mₛ and Hₑb.
• Voltage conditioning: Applying a bias to drive ion migration across layers, altering chemical composition and magnetic phase.
• Field-cooling reference state: Cooling the stack in a strong magnetic field establishes the reference alignment used to read Hₑb from hysteresis-loop offsets.
|
[{"label":"RBK Item","value":"Magneto-ionics (voltage-driven nitrogen motion): Application of an electric field drives nitrogen ions between MnNₓ and the adjacent Ta layer, reversibly altering the magnetic properties such as Mₛ and Hₑb.\n"},{"label":"Title","value":"Magneto-ionic control of interfacial magnetism"},{"label":"URL","value":"https://www.nature.com/articles/nmat4134"},{"label":"Date","value":"Nov 17, 2014"},{"label":"Justification (\"Paywalled\", \"OA\", \"Other (justify)\")","value":"Paywalled, but referenced in the paper as ref [10]"},{"label":"RBK Item","value":"Voltage conditioning: Applying a bias to drive ion migration across layers, altering chemical composition and magnetic phase.\n"},{"label":"Title","value":"Recent progress in voltage control of magnetism: Materials, mechanisms, and performance"},{"label":"URL","value":"https://www.sciencedirect.com/science/article/abs/pii/S0079642517300166"},{"label":"Date","value":"June, 2017"},{"label":"Justification (\"Paywalled\", \"OA\", \"Other (justify)\")","value":"Paywalled, but referenced in the paper as ref [4]"},{"label":"RBK Item","value":"Field-cooling reference state: Cooling the stack in a strong magnetic field establishes the reference alignment used to read Hₑb from hysteresis-loop offsets"},{"label":"Title","value":"Exchange Bias Theory: a Review"},{"label":"URL","value":"https://arxiv.org/abs/cond-mat/0107097"},{"label":"Date","value":"July 5, 2001"},{"label":"Justification (\"Paywalled\", \"OA\", \"Other (justify)\")","value":"OA"}]
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Physics
|
Optics and Photonics
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MCQ
|
The radial memory effect in multimode optical fibres
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https://arxiv.org/abs/2508.11389
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August 15, 2025
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Researchers illuminated the input facet of a step-index multimode fibre (core radius = 100 µm, numerical aperture NA ≈ 0.22, length = 20 cm) with a focused HeNe laser beam (λ = 633 nm) at programmable radial positions r_0. The fibre was subjected to mechanical perturbations (e.g., manual shaking) to vary its configuration. Both input and output facets were imaged simultaneously, and output speckle patterns were recorded and averaged over multiple fibre configurations or input angles at fixed $r_0$.
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• Radial projection profiles to identify annular patterns and verify correlation with input spots.
• Averaged intensity profiles after repeated fibre shaking and input positions
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In the experiment, a focused input spot is placed at radial position$r_0$ on the core of a step-index multimode fibre (20 cm long, NA ≈ 0.22, core radius = 100 µm), and the output is imaged after averaging over many fibre perturbations (e.g., manual shaking). Based on the experimental results, which of the following statements are supported by the data?
Mark all that apply.
A) A ring of excess intensity appears at radius r_0 in the output, even after fibre perturbations.
B) The radial memory effect enables reconstruction of discrete input positions from single-shot output intensity profiles.
C) Diagonal stripes aligned with the input azimuthal angle θ_0 are clearly visible in the averaged output.
D) The width of the output ring is independent of r_0 and is approximately diffraction-limited by the fibre’s NA.
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A) A ring of excess intensity appears at radius r_0 in the output, even after fibre perturbations.
B) The radial memory effect enables reconstruction of discrete input positions from single-shot output intensity profiles.
D) The width of the output ring is independent of r_0 and is approximately diffraction-limited by the fibre’s NA.
|
• Multimode fibre will accumulate different phases when propagating through the fibre, and interfere to form a speckle pattern.
• The radial memory effect is a reliable correlation that is robust against perturbations and does not depend on the fine details of the fibre.
• In multimode optical fibres, a "memory effect" refers to a predictable relationship between changes in the input light field and changes in the output speckle pattern, despite the apparent randomness of speckle.
• Small perturbations (e.g., bending) of a multimode fibre typically scramble the output speckle pattern by coupling between modes, making input–output correlations fragile.
• A focused spot at radial position r_0 on the input facet preferentially excites fibre modes that have significant field intensity at that radius, leading to residual correlations in the output.
|
[{"label":"RBK Item","value":"Multimode fibre will accumulate different phases when propagating through\nthe fibre, and interfere to form a speckle pattern.\n"},{"label":"Title","value":"Controlling light propagation in multimode fibers for imaging, spectroscopy and beyond"},{"label":"URL","value":"https://arxiv.org/abs/2305.09623"},{"label":"Date","value":"May 16, 2023"},{"label":"Justification (\"Paywalled\", \"OA\", \"Other (justify)\")","value":"OA"},{"label":"RBK Item","value":"The radial memory effect is a reliable correlation that is robust against per- turbations and does not depend on the fine details of the fibre.\n"},{"label":"Title","value":"Angular multiplexing for multichannel communication in a single fiber"},{"label":"URL","value":"https://ieeexplore.ieee.org/document/1070676/similar#similar"},{"label":"Date","value":"November 11, 1981"},{"label":"Justification (\"Paywalled\", \"OA\", \"Other (justify)\")","value":"Paywalled, but referenced in the paper as ref [17]"},{"label":"RBK Item","value":"In multimode optical fibres, a \"memory effect\" refers to a predictable relationship between changes in the input light field and changes in the output speckle pattern, despite the apparent randomness of speckle. "},{"label":"Title","value":"Polarization memory effect in a multimode fiber\n"},{"label":"URL","value":"https://arxiv.org/abs/2509.05665"},{"label":"Date","value":"September 6, 2025"},{"label":"Justification (\"Paywalled\", \"OA\", \"Other (justify)\")","value":"OA"},{"label":"RBK Item","value":"Small perturbations (e.g., bending) of a multimode fibre typically scramble the output speckle pattern by coupling between modes, making input–output correlations fragile"},{"label":"Title","value":"Speckle-correlation imaging through a kaleidoscopic multimode fiber\n"},{"label":"URL","value":"https://arxiv.org/abs/2212.14765"},{"label":"Date","value":"December 30, 2022"},{"label":"Justification (\"Paywalled\", \"OA\", \"Other (justify)\")","value":"OA"},{"label":"RBK Item","value":"A focused spot at radial position r_0 on the input facet preferentially excites fibre modes that have significant field intensity at that radius, leading to residual correlations in the output. "},{"label":"Title","value":"The radial memory effect in multimode optical fibres"},{"label":"URL","value":"https://arxiv.org/abs/2508.11389"},{"label":"Date","value":"August 15, 2025"},{"label":"Justification (\"Paywalled\", \"OA\", \"Other (justify)\")","value":"OA"}]
|
Physics
|
Physics/Plasma Physics
|
MCQ
|
Demonstration of full-scale spatio-temporal diagnostics of solid-density plasmas driven by an ultra-short relativistic laser pulse using an X-ray free-electron laser
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https://arxiv.org/abs/2505.06425
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May 9, 2025
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Researchers performed a pump-probe experiment at the High Energy Density (HED) station of the European X-ray Free-Electron Laser facility (XFEL-HED) to investigate solid-density plasma dynamics. Copper (Cu) wires with a diameter of 10 μm were irradiated at normal incidence by the ReLaX optical laser system (3 J, 30 fs, Ti:sapphire-based) focused to a FWHM spot size of approximately 4 μm, achieving a peak intensity of 5 × 10²⁰ W/cm². The laser was polarized in the horizontal direction. The plasma was probed by a femtosecond X-ray free-electron laser (XFEL) beam generated via self-amplified spontaneous emission (SASE) with energy of ~1.5 mJ, FWHM pulse duration of ~25 fs, and photon energy centered at 8.2 keV with a FWHM bandwidth of ~20 eV. The XFEL beam irradiated the wire at normal incidence, intersecting the optical laser at a 45° angle. Small angle X-ray scattering (SAXS) patterns were measured to probe preplasma expansion during the rising edge of the laser pulse from 40 ps to 1.5 ps before the main pulse arrival, corresponding to laser intensities ranging from ~10¹³ W/cm² to 10¹⁶ W/cm². Two Highly Annealed Pyrolytic Graphite (HAPG) mirrors located symmetrically below and above the XFEL beam propagation path were used to reflect the SAXS signal to Jungfrau X-ray detectors positioned 1.31 m downstream from the target.
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- SAXS intensity patterns normalized by incident XFEL energy (measured in keV/mJ) for shot-to-shot comparison
- Cold reference shots taken before each hot shot to establish baseline wire edge sharpness and XFEL-target overlap
- Hot shot measurements taken at multiple time delays: -40 ps; -30 ps; -20 ps; -10 ps; -5 ps; -3 ps; and -1.5 ps relative to the main laser pulse arrival
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Researchers at the European X-ray free-electron laser (XFEL) facility irradiated 10 $\mu$m diameter Cu wires with a 3 J, 30 fs ultra-high intensity laser ranging from ~10¹³ W/cm² to 10¹⁶ W/cm². Preplasma formation prior to the main pulse was probed via small angle X-ray scattering (SAXS) using 8.2 keV X-rays from the XFEL. SAXS intensity patterns were normalized by the incident XFEL energy. Which of the following outcomes are likely? Mark all correct options.
A. The preplasma forms and expands at least 0.3 ns before the main pulse
B. For the hot shot SAXS patterns, the intensity decreases with time delay from 40 to 1 ps before the main pulse
C. A constant SAXS intensity until after 150 ps, followed by a sudden drop
D. Cold wire electron scattering indicates uniform copper wire edge sharpness
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B. For the hot shot SAXS patterns, the intensity decreases with time delay from 40 to 1 ps before the main pulse
D. Cold wire electron scattering indicates uniform copper wire edge sharpness
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- The absolute laser absorption efficiency correlates with the scaling law of the generated hot electron temperature.
- Preplasma formation significantly influences laser absorption a few tens of picoseconds before the peak of the laser pulse is reached.
- Ultra-short brilliant X-ray free electron lasers such as that of the European XFEL-HED can be used to probe the ultrafast dynamics of solid-density plasmas via small-angle X-ray scattering.
- The SAXS intensity via XFEL is proportional to the spatial Fourier transformation of the electron density projected in the Xray beam direction.
|
[{"label":"RBK Item","value":"The absolute laser absorption efficiency correlates with the scaling of the generated hot electron temperature"},{"label":"Title","value":"Absolute laser energy absorption measurement of relativistic 0.7 ps laser pulses in nanowire arrays"},{"label":"URL","value":"https://pubs.aip.org/aip/pop/article/28/2/023302/124671"},{"label":"Date","value":"February 5, 2021"},{"label":"Justification (\"Paywalled\", \"OA\", \"Other (justify)\")","value":"OA, this is reference 7 in the paper"},{"label":"RBK Item","value":"Preplasma formation significantly influences laser absorption a few tens of picoseconds before the peak of the laser pulse is reached."},{"label":"Title","value":"Studying the Dynamics of Relativistic Laser-Plasma Interaction on Thin Foils by Means of Fourier-Transform Spectral Interferometry"},{"label":"URL","value":"https://journals.aps.org/prl/abstract/10.1103/PhysRevLett.118.255003"},{"label":"Date","value":"June 23, 2017"},{"label":"Justification (\"Paywalled\", \"OA\", \"Other (justify)\")","value":"OA, this is reference 2 in the paper"},{"label":"RBK Item","value":"Ultra-short brilliant X-ray free electron lasers such as that of the European XFEL-HED can be used to probe the ultrafast dynamics of solid-density plasmas via small-angle X-ray scattering."},{"label":"Title","value":"The High Energy Density Scientific Instrument at the European XFEL"},{"label":"URL","value":"https://journals.iucr.org/s/issues/2021/05/00/ay5578/index.html"},{"label":"Date","value":"August 23, 2021"},{"label":"Justification (\"Paywalled\", \"OA\", \"Other (justify)\")","value":"OA, this is reference 19 in the paper"},{"label":"RBK Item","value":"The SAXS intensity via XFEL is proportional to the spatial Fourier transformation of the electron density projected in the Xray beam direction."},{"label":"Title","value":"Using X-ray free-electron lasers for probing of complex interaction dynamics of ultra-intense lasers with solid matter"},{"label":"URL","value":"https://pubs.aip.org/aip/pop/article-abstract/21/3/033110/1032807"},{"label":"Date","value":"March 31, 2014"},{"label":"Justification (\"Paywalled\", \"OA\", \"Other (justify)\")","value":"Paywalled, this is reference 46 in the paper"}]
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Physics
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Biophysics
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Numerical Values
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Study on the Physical Properties and Application of a Novel Pharmaceutical Excipient Made from Starch and Cellulose Co-Processing
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https://www.mdpi.com/1424-8247/18/9/1389
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Sep 17, 2025
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The researchers studied the effect of coprocessing pregelatinized starch (PS) with microcrystalline cellulose (MCC) at different mass ratios on the micromeritic properties (powder density and flowability). The prepared samples were designated as PS, PS-MCC-91, PS-MCC-82, PS-MCC-73, and PS-MCC-55, corresponding to corn starch and MCC mass ratios of 10:0, 9:1, 8:2, 7:3, and 5:5, respectively. First step was gelatinization of the corn starch and MCC (1KG) mixture at various ratios by dispersing the contents in 4.8KG purified water under stirring followed by processing twice in colloid mill. Subsequently, 3.2 kg of anhydrous ethanol was added, and the mixture was placed in a glass reaction vessel. The reaction was conducted at 80 °C for 90 min with continuous stirring at 100 rpm, followed by centrifugation at 1000 rpm to remove the liquid phase. The gelatinization was confirmed through structural analysis using scanning electron microscopy (SEM) and Polarized Light Microscopy (PLM). The gelatinized gel was further transformed into suspension by utilizing the insolubility of PG in ethanol and isolated by centrifugation process. The resulting material was then dispersed in 75% (v/v) ethanol at room temperature with continuous stirring at 100 rpm for 30 min, followed by another centrifugation step at 1000 rpm to remove the liquid. The solid was then dried in a 105 °C forced-air drying oven until the loss on drying was between 3.0% and 8.0%, milled, and passed through an 80-mesh sieve to obtain the pregelatinized starch-microcrystalline cellulose co-processed material (PS-MCC). The flow properties of the powders were determined through calculation of Carr's index (%) using the bulk density and tapped density measurements of the powder samples.
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- Measuring the Bulk density (BD) ( in g/cm^3) of the powder sample and measuring the volume (V1).
- Measuring the Tapped Density (TD) (in g/cm^3) of the powder sample, and the volume was measured as (V2).
- Carr's Index (in %) calculation from BD and TD.
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The researchers studied the effect of coprocessing pregelatinized starch (PS) with microcrystalline cellulose (MCC) at different mass ratios on the micromeritic properties (powder density and flowability). The prepared samples were designated as PS-MCC-73, corresponding to a corn starch and MCC mass ratio of 7:3, as measured using a 100 mL graduated cylinder. The resulting material was then dispersed in ethanol at room temperature. Predict the Carr Index (in %) of PS-MCC-73.
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The Carr Index of PS-MCC-73 is 27.4 - 28.72 % (The given SD is 0.66% which is the fallback)
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- Pregelatinized starch (PS) is a modified starch, at the gelatinization temperature, starch granules swell, amylose leaches out, amylopectin double helix unwinds, and the crystalline structure disappears.
- The compressibility enhancement observed in co-processed systems cannot be replicated through mere physical blending of commercial pregelatinized starch and microcrystalline cellulose.
- During the co-processing of PS and MCC, no new covalent bonds were formed between the starch and MCC, indicating that only physical changes occurred, and no chemical reactions took place.
|
[{"label":"RBK Item","value":"Pregelatinized starch (PS) is a modified starch, at the gelatinization temperature, starch granules swell, amylose leaches out, amylopectin double helix unwinds, and the crystalline structure disappears."},{"label":"Title","value":"Observations on the impact of amylopectin and amylose structure on the swelling of starch granules"},{"label":"URL","value":"https://www.sciencedirect.com/science/article/abs/pii/S0268005X19323938?via%3Dihub"},{"label":"Date","value":"June, 2020"},{"label":"Justification (\"Paywalled\", \"OA\", \"Other (justify)\")","value":"Paywalled, but this is cited as reference 8 in the paper"},{"label":"RBK Item","value":"A Spray-Dried, Co-Processed Rice Starch as a Multifunctional Excipient for Direct Compression"},{"label":"Title","value":"https://www.mdpi.com/1999-4923/12/6/518"},{"label":"URL","value":"https://www.mdpi.com/1999-4923/12/6/518"},{"label":"Date","value":"June 6, 2020"},{"label":"Justification (\"Paywalled\", \"OA\", \"Other (justify)\")","value":"Open-access, this is cited as reference 24 in the paper"}]
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Physics
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Condensed Matter Physics
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Free-Format Question
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Flexible InGaAs/InAlAs avalanche photodiodes for short-wave infrared detection
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https://www.nature.com/articles/s41467-025-64401-2
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Oct 23, 2025
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The researchers have deposited the flexible thin-film InGaAs/InAlAs APDs on a mica substrate using a simple integration approach. Initially, all the III–V layers were grown on an InP substrate using a molecular beam epitaxy (MBE) system. Both the surface of the III–V wafer and the mica substrate underwent cleaning with acetone/isopropyl alcohol (IPA)/deionized (DI) water. Before bonding, the backside contact metal was sputtered on the InGaAs wafer using tungsten (W). Subsequently, the SU-8 layer was spin-coated on the mica substrate before bonding, followed by pre-baking at 110 °C for 60 s. The bonding process involved a flip-chip approach for the III–V layers, applying a force of 40 N/cm² at a temperature of 150 °C for 40 minutes. Once bonded onto the mica substrate, ultraviolet (UV) exposure was carried out from the back side of the wafer stack. The InP handle substrate was then removed using concentrated hydrochloric acid (HCl), with the wet etching stopping at the InGaAs etch-stop layer. Then the InGaAs etch-stop layer was partially etched. Subsequently, a few rounds of mesa etching were performed using a H3PO4/H2O2/H2O solution. Then, the device was passivated using a thin film of SU-8, followed by the application of top metallization. Probing pads were formed through metal sputtering and W etching, followed by thinning of the mica substrate. A tunable laser (Agilent 81949A) at 1520–1630 nm wavelengths, focused on 1550 nm used for I-V sweeps. A variable optical attenuator was used for incident power tuning, and the optical readout is realized by the optical power meter (Thorlabs PM100D) for the optical energy measurements and the optical spectrum analyzer (Tokogawa AQ6370B) for all the optical spectra. The device's photosensitive diameter is 60 μm, while the laser spot area is 10 μm in diameter. During the measurement, the flexible chip was stuck onto an annular holder with a certain radius. The electrical signal was applied and collected using a Keithley 1500 Analyzer.
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- Breakdown voltage in volts for flat conditions.
- Breakdown voltage in volts for bending radii ranging from 1 to 5 cm.
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A flexible thin-film InGaAs/InAlAs APD deposited on a mica substrate. The backside contact metal was sputtered on the InGaAs wafer using tungsten. Subsequently, the SU-8 layer was spin-coated on the mica substrate before bonding, followed by pre-baking at 110 °C for 60 s. The bonding process involved a flip-chip approach for the III–V layers, applying a force of 40 N/cm² at a temperature of 150 °C for 40 minutes. The InP handle substrate was then removed using concentrated hydrochloric acid (HCl), with the wet etching stopping at the InGaAs etch-stop layer. Then the InGaAs etch-stop layer was partially etched. Subsequently, a few rounds of mesa etching were performed. A tunable laser operating at 1520–1630 nm wavelengths, with a focus at 1550 nm, was used for I-V sweeps. A variable optical attenuator was used for incident power tuning, and the optical readout was realized by an optical power meter for optical energy measurements and an optical spectrum analyzer for all optical spectra.
What trend is observed for the breakdown voltage of the flexible InGaAs/InAlAs APD in terms of the bending radius as this radius is increased from 1 to 5 cm?
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The breakdown voltages of the flexible InGaAs/InAlAs APD at flat condition and bend condition of radii of 1 cm, 3 cm, and 5 cm are almost the same in all cases, so the breakdown voltages are remain mostly unchanged.
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- The mica substrate offers several advantages, including an atomically smooth surface, high transparency at SWIR, high thermal stability, chemical inertness, and biocompatibility. The mica substrate can be easily thinned down to the desired thickness.
- The bonding layer, SU-8, was chosen due to its high transmission at the SWIR range, good flexibility, and a Young’s modulus similar to that of the mica substrate.
- A double-mesa structure with a beveled edge termination method was introduced to guarantee the low leakage current and avoid the premature breakdown.
|
[{"label":"RBK Item","value":"The mica substrate offers several advantages, including an atomically smooth surface, high transparency at SWIR, high thermal stability, chemical inertness, and biocompatibility. The mica substrate can be easily thinned down to the desired thickness."},{"label":"Title","value":"Atomically thin mica flakes and their application as ultrathin insulating substrates for graphene"},{"label":"URL","value":"https://arxiv.org/abs/1109.2101"},{"label":"Date","value":"Sep, 2011"},{"label":"Justification (\"Paywalled\", \"OA\", \"Other (justify)\")","value":"Open-access, this is cited as reference 38 in the paper."},{"label":"RBK Item","value":"The bonding layer, SU-8, was chosen due to its high transmission at the SWIR range, good flexibility, and a Young’s modulus similar to that of the mica substrate. "},{"label":"Title","value":"Characterization of the mechanical behavior of SU-8 at microscale by viscoelastic analysis"},{"label":"URL","value":"https://iopscience.iop.org/article/10.1088/0960-1317/26/10/105001"},{"label":"Date","value":"Aug, 2016"},{"label":"Justification (\"Paywalled\", \"OA\", \"Other (justify)\")","value":"Paywalled, but this is cited as reference 35 in the paper."},{"label":"RBK Item","value":"A double-mesa structure with a beveled edge termination method was introduced to guarantee the low leakage current and avoid the premature breakdown. "},{"label":"Title","value":"High-performance InGaAs/InAlAs single-photon avalanche diode with a triple-mesa structure for near-infrared photon detection"},{"label":"URL","value":"https://opg.optica.org/ol/abstract.cfm?uri=ol-46-11-2670"},{"label":"Date","value":"May, 2021"},{"label":"Justification (\"Paywalled\", \"OA\", \"Other (justify)\")","value":"Paywalled, but this is cited as reference 30 in the paper."}]
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Physics
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Physics/Superconductivity
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MCQ
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Giant thermal modulation via a semiconductor-superconductor photonic field-effect heat transistor
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https://arxiv.org/pdf/2510.17683
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October 20, 2025
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A hybrid semiconductor–superconductor device was designed to study the electrical control of radiative heat flow between two isolated electronic reservoirs. The system includes a hot reservoir (Thot) and a cold reservoir (Tcold) made of InAs, separated by about 1 mm to eliminate phonon conduction. The reservoirs are connected only through capacitors and a Josephson field-effect transistor (JoFET), which modulates the exchange of thermal photons according to the applied gate voltage (Vg), controlled using the voltage source (Yokogawa GS200). Each reservoir contains a Josephson thermometer (JJ) that measures its local electronic temperature. The JoFET, fabricated with an Al/InAs/Al structure, changes its impedance from inductive to resistive depending on Vg, thereby affecting radiative coupling. The experiment was performed in a ³He–⁴He dilution refrigerator (Triton 200, Oxford Instruments) at a stabilized bath temperature Tbath = 30 mK. A heating current Iheat was applied to the hot reservoir, producing a controlled injected power Q̇inj = Rhot Iheat² ≈ 2.6 pW.
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- Hot reservoir temperature (Thot) was recorded by a Josephson thermometer ( for measuring local electronic temperature) located on the hot reservoir, at a stabilized bath temperature Tbath = 30 mK, with a controlled injected power Q̇inj = Rhot Iheat² ≈ 2.6 pW, and in the resistive state (Vg < –4 V).
- Cold reservoir temperature (Tcold) was recorded by a Josephson thermometer ( for measuring local electronic temperature) located on the cold reservoir, at a stabilized bath temperature Tbath = 30 mK, with a controlled injected power Q̇inj = Rhot Iheat² ≈ 2.6 pW, and in the resistive state (Vg < –4 V).
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An experiment investigated the electrical control of radiative heat transfer between two isolated electronic systems using a Josephson field-effect transistor (JoFET) acting as a photonic heat valve. The setup consisted of two InAs resistive reservoirs—one hot (Thot) and one cold (Tcold)—separated by about 1 mm to suppress any phonon-mediated conduction. The reservoirs were connected only through coupling capacitors (C₁, C₂) and the JoFET, ensuring purely radiative coupling. The gate voltage (Vg) applied to the JoFET, using a voltage source (Yokogawa GS200), tuned its impedance, thereby modulating the strength of photonic heat exchange. The device operated in a ³He–⁴He dilution refrigerator (Triton 200, Oxford Instruments) at a stabilized bath temperature (Tbath = 30 mK). A heating current (Iheat) applied to the hot reservoir generated an injected power Q̇inj = Rhot Iheat² ≈ 2.6 pW. The cold reservoir temperature (Tcold) was then measured using Josephson thermometers for the resistive state (Vg = –4 V) and Thot (varying in the range, 270–470 mK). These measurements allowed the determination of the maximum modulation of the cold temperature (δTcold) for each condition. Which of the following statements correctly describes how the amplitude of thermal modulation δTcold is expected to depend on the hot reservoir temperature Thot?
A. δTcold increases with Thot, because the total heat current grows, providing a larger absolute flux for the JoFET to modulate.
B. δTcold decreases as Thot increases, because higher-frequency thermal radiation is more strongly affected by capacitive shunting of the JoFET gate.
C. δTcold is constant, as the gate voltage modulates a fixed impedance ratio, making the modulation depth independent of the input spectrum.
D. δTcold peaks at a specific Thot, where the blackbody peak frequency aligns with the JoFET's gate-tunable resonance for maximum interference.
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B. δTcold decreases as Thot increases, because higher-frequency thermal radiation is more strongly affected by capacitive shunting of the JoFET gate.
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- Johnson-Nyquist noise, which occurs when two resistive reservoirs at different temperatures are interconnected through an electrical circuit.
- Josephson field-effect transistor (JoFET) is a hybrid superconducting–semiconducting device that electrostatically tunes thermal transport.
- Inductive and resistive regimes are the two operational states of the JoFET determined by the gate voltage: the inductive regime allows strong photonic coupling, while the resistive regime suppresses it.
|
[{"label":"RBK Item","value":"Johnson-Nyquist noise, which occurs when two resistive reservoirs at different temperatures are interconnected through an electrical circuit."},{"label":"Title","value":"Thermal Agitation of Electric Charge in Conductors"},{"label":"URL","value":"https://journals.aps.org/pr/abstract/10.1103/PhysRev.32.110"},{"label":"Date","value":"July 1, 1928"},{"label":"Justification (\"Paywalled\", \"OA\", \"Other (justify)\")","value":"Paywalled"},{"label":"RBK Item","value":"Josephson field-effect transistor (JoFET) is a hybrid superconducting–semiconducting device that electrostatically tunes thermal transport."},{"label":"Title","value":"Extremely weak sub-kelvin electron-phonon coupling in InAs On Insulator"},{"label":"URL","value":"https://arxiv.org/abs/2406.15040"},{"label":"Date","value":"June 21, 2024"},{"label":"Justification (\"Paywalled\", \"OA\", \"Other (justify)\")","value":"OA"},{"label":"RBK Item","value":"Inductive and resistive regimes are the two operational states of the JoFET determined by the gate voltage: the inductive regime allows strong photonic coupling, while the resistive regime suppresses it."},{"label":"Title","value":"Josephson Field Effect Transistors with InAs on Insulator and High Permittivity Gate Dielectrics"},{"label":"URL","value":"https://arxiv.org/abs/2412.16221"},{"label":"Date","value":"December 18, 2024"},{"label":"Justification (\"Paywalled\", \"OA\", \"Other (justify)\")","value":"OA"}]
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Physics
|
Spintronics, Experimental Condensed Matter Physics.
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Numerical Values
|
High-speed antiferromagnetic domain walls driven by coherent spin waves
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https://www.nature.com/articles/s42003-025-08989-7
|
Nov 7, 2025
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An antiferromagnetic Sr2Cu3O4Cl2 sample was grown by an optimized method of slow cooling from the melt. Quantities of SrO, SrCl2, and CuO powders were mixed in a 1:1:3 stoichiometric ratio and placed in a large high-form alumina crucible. The mix was gradually heated in air at 1030 °C, dwelled for 5 hours, then cooled to 900 °C at a rate of 2 °C per hour. Placing the crucible in a slight temperature gradient (off-center of the hot chamber of the box furnace) resulted in a cm-sized plate-like single crystal. The samples showed excellent stability in air. X-ray diffraction, Laue X-ray diffraction, and low-temperature magnetization measurements were used to verify the high sample quality. The samples were affixed to an oxygen-free high-thermal-conductivity copper mount using a small amount of silver epoxy and then cleaved before measurement to leave clean surfaces parallel to the Cu3O4 (001) planes. SHG rotational anisotropy measurements were carried out using a fast-rotating scattering plane-based technique. The laser pulses are delivered by a Ti:sapphire amplifier (800 nm fundamental wavelength, 100 fs pulse duration, 100 kHz repetition rate). The beam diameter was 40 μm with a fluence of 3 mJ/cm2. To quantify the light-driven DW motion, the temporal evolution of the wall center position and velocity for different pump helicities was analyzed at the location of maximum DW displacement for 1200 ps.
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- Position of the DW center measured for linear, LCP, and RCP pump polarizations at 1200 ps.
- Velocity of the DW center measured for linear, LCP, and RCP pump polarizations at 1200 ps.
|
An antiferromagnetic Sr2Cu3O4Cl2 sample was grown by an optimized method of slow cooling from the melt. The samples were affixed to an oxygen-free, high-thermal-conductivity copper mount using a small amount of silver epoxy and then cleaved before measurement. To quantify the light-driven domain wall (DW) motion, the temporal evolution of the wall center position and velocity was analyzed at the location of maximum DW displacement for 1200 ps, for different pump helicities. Time-resolved SHG imaging was performed by splitting off 800 nm light from the same laser source to produce the pump beam. Predict the maximum velocity of DW center (in km/sec)?
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The maximum velocity of the DW center is 45 - 55 km/sec (with given fallback of ±5 km/sec)
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- Ultrafast laser pulses are a versatile way to generate nonthermal magnons in antiferromagnets, so it is possible to induce intense coherent AFM spin waves with ultrafast laser light through inverse magnetooptical processes.
- Ultrafast stroboscopic pump-probe experiments require the sample to return to its initial state after excitation, complicating the visualization of irreversible DW dynamics.
- The SHG rotational anisotropy can detect ferromagnetic moment (m) and Néel vector (n), enabling direct visualization of AFM domains and DWs.
|
[{"label":"RBK Item","value":"Ultrafast laser pulses are a versatile way to generate nonthermal magnons in antiferromagnets, so it is possible to induce intense coherent AFM spin waves with ultrafast laser light through inverse magnetooptical processes."},{"label":"Title","value":"Ultrafast non-thermal control of magnetization by instantaneous photomagnetic pulses"},{"label":"URL","value":"https://www.nature.com/articles/nature03564"},{"label":"Date","value":"May 25, 2005"},{"label":"Justification (\"Paywalled\", \"OA\", \"Other (justify)\")","value":"Paywalled, but this is cited as reference 36 in the paper"},{"label":"RBK Item","value":"Ultrafast stroboscopic pump-probe experiments require the sample to return to its initial state after excitation, complicating the visualization of irreversible DW dynamics. "},{"label":"Title","value":"Ultrafast high-harmonic nanoscopy of magnetization dynamics"},{"label":"URL","value":"https://www.nature.com/articles/s41467-021-26594-0"},{"label":"Date","value":"Nov 3, 2021"},{"label":"Justification (\"Paywalled\", \"OA\", \"Other (justify)\")","value":"Open-access, this is cited as reference 45 in the paper"},{"label":"RBK Item","value":"The SHG rotational anisotropy can detect ferromagnetic moment (m) and Néel vector (n), enabling direct visualization of AFM domains and DWs. "},{"label":"Title","value":"Direct visualization and control of antiferromagnetic domains and spin reorientation in a parent cuprate"},{"label":"URL","value":"https://journals.aps.org/prb/abstract/10.1103/PhysRevB.106.L140403"},{"label":"Date","value":"Oct 12, 2022"},{"label":"Justification (\"Paywalled\", \"OA\", \"Other (justify)\")","value":"Paywalled, but this is cited as reference 50 in the paper"}]
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Physics
|
Physics/Nuclear Experiment
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Numerical Values
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Recent Highlights from the STAR Experiment
|
https://arxiv.org/abs/2508.08444
|
August 11, 2025
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Researchers investigated the Beam Energy Scan-II (BES-II) program at the STAR experiment, which was used to measure net-proton cumulant ratios in Gold-on-Gold (Au+Au) collisions at various center-of-mass energies (from 7.7 to 27 GeV) in the Fixed-Target mode. BES-II employed a new centrality definition, RefMult3X, corresponding to pseudorapidity acceptances fulfilling |𝜂| < 1.6. The Time-Projection Chamber (TPC) for low transverse momentum (0.4 < pT < 0.8 GeV/c) and the Time-Of-Flight (TOF) detector for greater transverse momentum (0.8 < pT < 2.0 GeV/c) were used to identify protons and anti-protons. Only particles falling within the speed window of |y| < 0.5 were included in the analysis. The most central collisions (0-5% centrality class) were the focus of the measurements, which were methodically adjusted for experimental variables such detector efficiency, event pile-up, and centrality bin width.
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- Net-proton cumulants (C1, C2, C3, C4) as a function of collision centrality and collision energy.
- The relative dynamical correlation of transverse momentum as a function of collision energy.
|
In the STAR experiment's Beam Energy Scan-II (BES-II), what was the measured value of the net-proton cumulant ratio C4/C2 at the collision energy of 19.6 GeV for the 0-5% centrality class?
|
[0.25-0.40]
Note: The range is informed graphically in Figure 3. The range was estimated by the pixel coordinates of the error bars and axis ticks.
|
- The upgrades done to STAR for BES-II enabled a new centrality definition, RefMult3X, which achieves better centrality resolution due to larger multiplicity within the acceptance.
- Experimentally measured proton multiplicity distributions are described by the central moments, which depend on the cumulants. In particular, the second cumulant C2 is the variance $\sigma^2$, and the ratio between the fourth and second cumulant, C4/C2, is $\kappa \sigma^2$, where $\kappa$ is the kurtosis.
- When there are no intrinsic correlations among the measured particles, all ratios of the cumulants are unity, so Poisson statistics is a trivial baseline for experimentally measured cumulant ratios.
|
[{"label":"RBK Item","value":"When there are no intrinsic correlations among the measured particles, all ratios of the cumulants are unity, so Poisson statistics is a trivial baseline for experimentally measured cumulant ratios."},{"label":"Title","value":"Hadronic fluctuations at the QCD phase transition"},{"label":"URL","value":"https://doi.org/10.1016/j.physletb.2005.11.083"},{"label":"Date","value":"Feb 9, 2006"},{"label":"Justification (\"Paywalled\", \"OA\", \"Other (justify)\")","value":"OA, cited as reference 9."}]
|
Physics
|
Physics/Nuclear physics
|
Numerical Values
|
Neutron capture measurement of the ${}^{165}\mathrm{Ho}$ at the CSNS Back−n facility in the resonance energy region
|
https://arxiv.org/pdf/2510.22965
|
October 27, 2025
|
Researchers conducted a neutron capture experiment in a time-of-flight facility with neutron energies between 0.3 eV and 200 MeV. Measurements were carried out at a station located 76 m apart of the spallation target, where the flux is $6.9\times 10^5$ cm${}^{-2}$s${}^{-1}$ with selectable beam spots between 20 mm and 60 mm. The neutron spectrum was monitored using a ${}^6$Li-Si detector and a ${}^{235}$U fission chamber, while a silicon flux monitor with a thin ${}^{6}$LiF converter and eight off-axis detectors provided continuous beam normalization. Gamma rays were detected with a spherical array of 40 BaF${}_2$ crystals (20 cm inner diameter, 15 cm thickness) calibrated with ${}^{60}$Co and ${}^{137}$Cs sources. On the other hand, the target was a 30 mm-diameter, 0.2 mm-thick metallic Ho disk (99.5% of ${}^{165}$Ho, with $6.4\times 10^{-4}$ atoms/barn, and a mass of 1243.32 mg). The ${}^{165}$Ho sample was measured for 11 hours to obtain sufficient capture events statistics. Additionally, a sample of carbon (1597.5 mg, 1 mm-thick) and the empty sample holder were measured for 3 hours and 12 hours, respectively.
|
- Total deposited energy for ${}^{165}$Ho (counts vs event energy).
- Total deposited energy for carbon (counts vs event energy).
- Total deposited energy for empty sample holder (counts vs event energy).
|
In a neutron capture study of ${}^{165}$Ho, 18 resolved s-wave resonances below 100 eV were measured whit a level spacing of 4.53(3) eV to determine the individual radiative widths. What is mean radiative width (in meV) for s-wave resonances of ${}^{165}$Ho obtained from these measurements?
|
The mean radiative width is [86.12‒90.08] meV (The given fallback is ±1.98meV).
|
- Holmium shares several favorable features with gold: it exhibits a well-resolved and representative prompt-γ spectrum following neutron capture.
- Odd-odd nuclei such as 166Ho remain a stringent test bed for microscopic approaches, shell model calculations, collective models, and the interacting boson framework still face difficulties in reproducing their level schemes and decay patterns.
- The average level spacing, defined as the mean energy difference between consecutive resonance levels, is a fundamental quantity that reflects the density of nuclear states at the neutron separation energy.
|
[{"label":"RBK Item","value":"Holmium shares several favorable features with gold: it exhibits a well-resolved and representative prompt-γ spectrum following neutron capture."},{"label":"Title","value":"Determination of Spins of Neutron Resonances and the Hyperfine Coupling Constant in Ho165"},{"label":"URL","value":"https://journals.aps.org/pr/abstract/10.1103/PhysRev.137.B1484"},{"label":"Date","value":"Mar 22, 1965"},{"label":"Justification (\"Paywalled\", \"OA\", \"Other (justify)\")","value":"Paywalled, but this is cited as reference 7 in the paper"},{"label":"RBK Item","value":"Odd-odd nuclei such as 166Ho remain a stringent test bed for microscopic approaches, shell model calculations, collective models, and the interacting boson framework still face difficulties in reproducing their level schemes and decay patterns."},{"label":"Title","value":"Self-consistent mean-field models for nuclear structure"},{"label":"URL","value":"https://journals.aps.org/rmp/abstract/10.1103/RevModPhys.75.121"},{"label":"Date","value":"Jan 23, 2003"},{"label":"Justification (\"Paywalled\", \"OA\", \"Other (justify)\")","value":"Paywalled, but this is cited as reference 10 in the paper"}]
|
Biology
|
Microbial ecology
|
MCQ
|
Litter nutrient release and allelopathy jointly contribute to the diversity–invasibility relationship
|
https://besjournals.onlinelibrary.wiley.com/doi/10.1111/1365-2435.70190
|
October 8, 2025
|
The experiment was conducted in Kunyu Mountain National Nature Reserve, Shandong Peninsula (China), with an annual precipitation of 900–1000 mm and an average annual temperature of 11.8°C. Fifteen common native species were selected for this experiment: Q. glandulifera, Q. variabilis, Q. acutissima, Alnus hirsuta, Kalopanax septemlobus, Sorbus alnifolia, Ailanthus altissima, Pinus densiflora, Rhus chinensis, Grewia biloba var. parviflora, Lespedeza bicolor, Indigofera kirilowii, Prunus japonica, Celastrus orbiculatus, Smilax china. Representative litter material was collected for each species from three plots (50x50 m) spaced 500 m apart. Healthy individuals of a similar size were selected, with a minimum 10m between individuals. Leaves were collected from branches and cut into 1 cm fragments, and air-dried at room temperature.
Litter was mixed into 61 litter combinations, each containing 6 g of litter with equal species contributions: 15 species combinations each containing 1, 3, 6, or 9 species, plus a single 15-species combination. Forest soil was then collected, sieved to remove roots and debris with a 1 cm sieve, and placed in 16x18 cm 1.5 L pots. Litter samples were placed on top of the soil surface of 305 pots (61 combinations, 5 replications per combination). After 10 weeks, the remaining litter was removed, and the amounts of C and N lost during decomposition were calculated as the average mass loss of each combination and corresponding changes in concentration relative to initial litter quality. Initial litter quality was measured using three subsamples of litter of each species. Samples were ground into fine powder and analysed with an elemental analyser.
|
- Carbon release (%) in plant litter from initial and final concentrations after 10 weeks of soil exposure, at increasing levels of litter species richness (1, 3, 6, 9, and 15 species).
- Nitrogen release (%) in plant litter from initial and final concentrations after 10 weeks of soil exposure, at increasing levels of litter species richness (1, 3, 6, 9, and 15 species).
|
Researchers evaluated the effects of plant litter diversity on the release of carbon and nitrogen from native plant litter in the Kunyu Mountain National Nature Reserve, China. The amounts of carbon and nitrogen remaining in each litter mixture were measured before and after 10 weeks of exposure to forest soil. The samples varied in species richness, containing 1, 3, 6, 9, or 15 species. Given the carbon and nitrogen release measurements in relation to litter richness, which outcome is more likely?
A. Carbon and nitrogen release within the litter decreased with decreasing litter richness
B. Carbon and nitrogen release within the litter decreased with increasing litter richness
C. Carbon and nitrogen release within the litter did not change with increasing litter richness
D. Nitrogen release increases, but carbon decreases within the litter as litter richness increases.
|
B. Carbon and nitrogen release within the litter decreased with increasing litter richness
|
- Plant litter: a key factor shaping soil nutrient availability, chemical profiles and microbial communities.
- Litter diversity: litter mixing can alter chemical composition and reshape soil microbial communities.
|
[{"label":"RBK Item","value":"Litter diversity: litter mixing can alter chemical composition and reshape soil microbial communities. "},{"label":"Title","value":"Diversity meets decomposition"},{"label":"URL","value":"https://www.cell.com/trends/ecology-evolution/abstract/S0169-5347(10)00039-X?_returnURL=https%3A%2F%2Flinkinghub.elsevier.com%2Fretrieve%2Fpii%2FS016953471000039X%3Fshowall%3Dtrue"},{"label":"Date","value":"March 02, 2010"},{"label":"Justification (\"Paywalled\", \"OA\", \"Other (justify)\")","value":"Paywalled"},{"label":"RBK Item","value":"Plant litter: a key factor shaping soil nutrient availability, chemical profiles and microbial communities."},{"label":"Title","value":"The Role of Plant Litter in Driving Plant-Soil Feedbacks"},{"label":"URL","value":"https://www.frontiersin.org/journals/environmental-science/articles/10.3389/fenvs.2019.00168/full"},{"label":"Date","value":"October 22, 2019"},{"label":"Justification (\"Paywalled\", \"OA\", \"Other (justify)\")","value":"OA"}]
|
Biology
|
Environmental Microbiology
|
MCQ
|
Artificial Endosymbiosis of Pedobacter sp. DDGJ Boosts the Growth Potential, Stress Resistance and Productivity of Morchella Mushrooms
|
https://enviromicro-journals.onlinelibrary.wiley.com/doi/full/10.1111/1751-7915.70197
|
July 12, 2025
|
This experiment examined how artificially induced endosymbiosis with a bacterium of the genus Pedobacter affected the dry weights of mycelial cultures of three Morchella species under different culture conditions, including stressful conditions. Three previously domesticated, positively identified strains of Morchella, M. sextelata 13, M. eximia SM and M. importuna Y2, were obtained as culture slants. For activation, 4 mm diameter agar disks were transferred from the slants onto 90 mm diameter petri dishes containing 15ml each of complete yeast extract medium (CYM) (glucose 20 g/L, yeast extracts 2.0 g/L, peptone 2.0 g/L, K2HPO4 1.0 g/L, MgSO4 0.50 g/L, KH2PO4 0.46 g/L and agar 20 g/L) and incubated in the dark for three days at 24°C. Using a conventional dilution method, bacteria were obtained from samples of soil taken from underneath morel fruiting bodies growing in field conditions and identified only to genus level, based on 16S rDNA phylogenetic analysis. The isolate of Pedobacter sp. was designated as DDGJ. To establish endosymbiosis with the Morchella strains, the left sides of new CYM plates were then streaked with bacterial culture; 4 mm agar disks cut from the periphery of the above-described three-day-old plates of Morchella strains 13, SM, and Y2, were then inoculated at 2 cm distance from the bacterial streaks. The co-cultures were incubated inversely for 14 days at 14°C, at which point mycelia growing on the dish inner walls on the side of the bacterial inoculum were transferred to CYM slants. Several further rounds of isolation from slant walls to new slants were used to obtain pure mycelial cultures, until no sign of bacterial growth was visible. These putatively endosymbiotic strains of 13, SM and Y2 were designated P-13, P-SM and P-Y2, respectively. To compare the performance of strains in varying temperatures, 4mm agar disks of the endosymbiotic and parental morel strains were transferred to sterile cellophane membranes in the centre of new CYM plates and incubated at 16°C, 20°C or 24°C for one week. To compare the performance of strains in varying conditions of pH and allelotoxin concentrations, cultures on new CYM plates adjusted to pH 6, 7, and 8, and on CYM plates with 0, 0.02, 0.2 and 1.0 mM 4-coumaric acid, were also initiated in the same way, then incubated in the dark at 24°C for one week. Each strain + treatment combination was replicated three times. Fresh mycelia were then harvested from the cellophane membranes and dried to a constant weight at 50°C. The resultant dry biomass was weighed.
|
- Biomass (g) of endosymbiotic strains (P-13, P-SM and P-Y2) and Morchella strains (13, SM, and Y2) incubated at 16°C, 20°C or 24°C for one week.
- Biomass (g) of endosymbiotic strains (P-13, P-SM and P-Y2) and Morchella strains (13, SM, and Y2) grown on CYM plates with pH 6, 7, and 8 for one week and grown at 24°C.
- Biomass (g) of endosymbiotic strains (P-13, P-SM and P-Y2) and Morchella strains (13, SM, and Y2) grown on CYM plates treated with allelotoxin concentrations (0, 0.02, 0.2 and 1.0 mM 4-coumaric acid) for one week and grown at 24°C.
|
This experiment examined how artificially induced endosymbiosis with a bacterium of the genus Pedobacter affected the dry weights of mycelial cultures of three Morchella species under different culture conditions, including stressful conditions. Three previously domesticated, positively identified strains of Morchella, M. sextelata 13, M. eximia SM and M. importuna Y2, were obtained as culture slants. For activation, 4 mm diameter agar disks were transferred from the slants onto 90 mm diameter petri dishes containing 15ml each of complete yeast extract medium (CYM) (glucose 20 g/L, yeast extracts 2.0 g/L, peptone 2.0 g/L, K2HPO4 1.0 g/L, MgSO4 0.50 g/L, KH2PO4 0.46 g/L and agar 20 g/L) and incubated in the dark for three days at 24°C. Using a conventional dilution method, bacteria were obtained from samples of soil taken from underneath morel fruiting bodies growing in field conditions and identified only to genus level, based on 16S rDNA phylogenetic analysis. The isolate of Pedobacter sp. was designated as DDGJ. To establish endosymbiosis with the Morchella strains, the left sides of new CYM plates were then streaked with bacterial culture; 4 mm agar disks cut from the periphery of the above-described three-day-old plates of Morchella strains 13, SM, and Y2, were then inoculated at 2 cm distance from the bacterial streaks. The co-cultures were incubated inversely for 14 days at 14°C, at which point mycelia growing on the dish inner walls on the side of the bacterial inoculum were transferred to CYM slants. Several further rounds of isolation from slant walls to new slants were used to obtain pure mycelial cultures, until no sign of bacterial growth was visible. These putatively endosymbiotic strains of 13, SM and Y2 were designated P-13, P-SM and P-Y2, respectively. To compare the performance of strains in varying temperatures, 4mm agar disks of the endosymbiotic and parental morel strains were transferred to sterile cellophane membranes in the centre of new CYM plates and incubated at 16°C, 20°C or 24°C for one week. To compare the performance of strains in varying conditions of pH and allelotoxin concentrations, cultures on new CYM plates adjusted to pH 6, 7, and 8, and on CYM plates with 0, 0.02, 0.2 and 1.0 mM 4-coumaric acid, were also initiated in the same way, then incubated in the dark at 24°C for one week. Each strain + treatment combination was replicated three times. Fresh mycelia were then harvested from the cellophane membranes and dried to a constant weight at 50°C. The resultant dry biomass was weighed. Which of the following outcomes are expected? Mark all the correct options.
A) The biomasses of the endosymbiotic strains in all of the three concentrations (0, 0.02, 0.2, 1.0 mM) of 4-coumaric acid were all significantly higher than their parental strains.
B) The biomasses of the endosymbiotic strains were all significantly higher than their parental strains at the 20°C and 24°C incubation temperatures, but not at 16°C, possibly because the growth of the productivity-boosting Pedobacter endosymbiont was inhibited at this temperature.
C) The biomasses of the endosymbiotic strains in all of the three different pH treatments was significantly higher than their parental strains, showing that the productivity-boosting effects of endosymbiosis are relatively independent of soil pH conditions.
D) The biomasses of the endosymbiotic strains was highly significantly greater than their parental strains in the 0.02 mM 4-coumaric acid treatment, and not significantly greater than their parental strains in the 1.0 mM treatment.
|
A) The biomasses of the endosymbiotic strains in all of the three concentrations (0, 0.02, 0.2, 1.0 mM) of 4-coumaric acid were all significantly higher than their parental strains.
C) The biomasses of the endosymbiotic strains in all of the three different pH treatments was significantly higher than their parental strains, showing that the productivity-boosting effects of endosymbiosis are relatively independent of soil pH conditions.
|
- True morels in the genus Morchella (Pezizales, Ascomycota) are choice edible species of great commercial value; however, their cultivation in field conditions faces challenges like varying temperatures, soil pH, alterations in soil microbial communities, aggravation of soil-borne disease, allelopathy and autotoxicity.
- Morchella spp. are associated with a diverse soil bacterial microbiome, including Pedobacter sp with which they have complex ecological interactions, including potentially beneficial ones that promote growth and ascocarp development.
- Some microbiome bacteria can inhabit fungi intracellularly, forming endosymbioses that modulate fungal vigor, metabolite production and stress resistance.
- Endosymbioses are beneficial associations between organisms of unequal size in which the smaller endosymbiont is located within the larger host.
|
[{"label":"RBK Item","value":"- True morels in the genus Morchella (Pezizales, Ascomycota) are choice edible species of great commercial value; however, their cultivation in field conditions faces challenges like varying temperatures, soil pH, alterations in soil microbial communities, aggravation of soil-borne disease, allelopathy and autotoxicity."},{"label":"Title","value":"Artificial cultivation of true morels: current state, issues and perspectives"},{"label":"URL","value":"https://www.tandfonline.com/doi/full/10.1080/07388551.2017.1333082"},{"label":"Date","value":"June 6, 2017"},{"label":"Justification (\"Paywalled\", \"OA\", \"Other (justify)\")","value":"Paywalled"},{"label":"RBK Item","value":"- Morchella spp. are associated with a diverse soil bacterial microbiome, including Pedobacter sp with which they have complex ecological interactions, including potentially beneficial ones that promote growth and ascocarp development."},{"label":"Title","value":"Microbial communities associated with the black morel Morchella sextelata cultivated in greenhouses"},{"label":"URL","value":"https://peerj.com/articles/7744/"},{"label":"Date","value":"September 26, 2019"},{"label":"Justification (\"Paywalled\", \"OA\", \"Other (justify)\")","value":"OA"},{"label":"RBK Item","value":"-Some microbiome bacteria can even inhabit fungi intracellularly, forming endosymbioses that modulate fungal vigor, metabolite production and stress resistance."},{"label":"Title","value":"Diverse Bacteria Inhabit Living Hyphae of Phylogenetically Diverse Fungal Endophytes"},{"label":"URL","value":"https://journals.asm.org/doi/full/10.1128/aem.02928-09"},{"label":"Date","value":"June 15, 2010"},{"label":"Justification (\"Paywalled\", \"OA\", \"Other (justify)\")","value":"OA"},{"label":"RBK Item","value":"- Endosymbioses are beneficial associations between organisms of unequal size in which the smaller endosymbiont is located within the larger host."},{"label":"Title","value":"Are endosymbioses mutualistic?"},{"label":"URL","value":"https://www.sciencedirect.com/science/article/abs/pii/0169534789900906"},{"label":"Date","value":"November, 1989"},{"label":"Justification (\"Paywalled\", \"OA\", \"Other (justify)\")","value":"Paywalled"}]
|
Biology
|
Molecular Biology
|
MCQ
|
Disrupting Notch signalling by a small molecule inhibiting dihydroorotate dehydrogenase activity
|
https://www.biorxiv.org/content/10.1101/2025.09.29.679158v1.full
|
September 30, 2025
|
In the dose-response analyses, the researchers quantified the potency of candidate Notch inhibitors identified from the primary and counter screens by determining their half-maximal inhibitory concentrations (IC₅₀). The experiment used a stably transfected 293T Notch reporter cell line expressing firefly luciferase under the control of CSL-binding sites and a Renilla luciferase reporter for normalization. Compounds were prepared as 11-point serial dilutions ranging from 4.00 × 10⁻⁵ M to 3.91 × 10⁻⁸ M, and in later analyses as 14-point dilution series between approximately 4.00 × 10⁻⁵ M and 2.51 × 10⁻¹¹ M, distributed using Agilent Bravo and Labcyte Echo 650 liquid-handling systems. Reporter cells (4,000 cells per well) were seeded in 384-well white plates in 20 µL medium containing either test compounds or controls, and incubated for 24 hours at 37 °C with 5% CO₂. Each plate included DMSO vehicle controls (baseline activity) and positive inhibition controls—either 10 µM DAPT or LY-411575 (γ-secretase inhibitors)—to define assay limits. After incubation, 20 μl firefly luciferase substrate was added to each well using an automated dispenser system (Multidrop, ThermoFisher), followed by incubation with thorough agitation for 10 min in the dark. Next, firefly luciferase signals were read on a Wallac Victor3 1420 plate reader (Perkin Elmer; signal integration time = 0.5 sec). Dispenser casetters were changed after reading the firefly signals, and 20 μl of renilla firefly substrate was added to plates, incubated for 10 mins in the dark, after which the resulting renilla luciferase signals were read. Thus, the Dual-GLO Luciferase Assay (Promega) was used to measure luminescence, with firefly and Renilla signals detected sequentially on a Wallac Victor³ or SpectraMax i3 plate reader (signal integration times = 0.5 s for Notch assays, 0.1 s for APP assays). Data were normalised as firefly/Renilla ratios relative to the DMSO control value of the plate. Additionally, dose-response curves, IC₅₀ and Hill slope values were computed.
|
- Firefly luciferase signals from 293T Notch reporter cell line expressing firefly luciferase after 24 hours treatment with DMSO (vehicle control), either 10 µM DAPT or LY-411575 (positive control), 11-point serial dilutions ranging from 4.00 × 10⁻⁵ M to 3.91 × 10⁻⁸ M, and 14-point dilution series between approximately 4.00 × 10⁻⁵ M and 2.51 × 10⁻¹¹ M.
- Renila luciferase signals from 293T Notch reporter cell line expressing firefly luciferase after 24 hours treatment with DMSO (vehicle control), either 10 µM DAPT or LY-411575 (positive control), 11-point serial dilutions ranging from 4.00 × 10⁻⁵ M to 3.91 × 10⁻⁸ M, and 14-point dilution series between approximately 4.00 × 10⁻⁵ M and 2.51 × 10⁻¹¹ M.
- Dose-response curve showing firefly/Renilla ratios relative to the DMSO control of 293T Notch reporter cell line expressing firefly luciferase after 24 hours treatment with DMSO (vehicle control), either 10 µM DAPT or LY-411575 (positive control), 11-point serial dilutions ranging from 4.00 × 10⁻⁵ M to 3.91 × 10⁻⁸ M, and 14-point dilution series between approximately 4.00 × 10⁻⁵ M and 2.51 × 10⁻¹¹ M.
|
Researchers stably transfected 293T Notch reporter cell line expressing firefly luciferase under the control of CSL-binding sites and a Renilla luciferase reporter. Then, test chemical compounds were prepared as 11-point serial dilutions ranging from 4.00 × 10⁻⁵ M to 3.91 × 10⁻⁸ M, and in later analyses as 14-point dilution series between approximately 4.00 × 10⁻⁵ M and 2.51 × 10⁻¹¹ M. These dilutions of test compounds were then distributed using Agilent Bravo and Labcyte Echo 650 liquid-handling systems. Reporter cells (4,000 cells per well) were then seeded in 384-well white plates in 20 µL medium containing either test compounds or controls, and incubated for 24 hours at 37 °C with 5% CO₂. Each plate included DMSO vehicle controls (baseline activity) and positive inhibition controls—either 10 µM DAPT or LY-411575 (γ-secretase inhibitors)—to define assay limits. After incubation, 20 μl firefly luciferase substrate was added to each well using an automated dispenser system (Multidrop, ThermoFisher), followed by incubation with thorough agitation for 10 min in the dark. Next, firefly luciferase signals were read on a Wallac Victor3 1420 plate reader (Perkin Elmer; signal integration time = 0.5 sec). Dispenser casetters were changed after reading the firefly signals, and 20 μl of renilla firefly substrate was added to plates, incubated for 10 mins in the dark, after which the resulting renilla luciferase signals were read. Thus, the Dual-GLO Luciferase Assay (Promega) was used to measure luminescence, with firefly and Renilla signals detected sequentially on a Wallac Victor³ or SpectraMax i3 plate reader (signal integration times = 0.5 s for Notch assays, 0.1 s for APP assays). Data were normalised as firefly/Renilla ratios relative to the DMSO control value of the plate. Additionally, dose-response curves, IC₅₀ and Hill slope values were computed. In the dose-response analysis experiment, researchers treated the 293T Notch reporter cell line with dilutions of the test compounds to assess Notch pathway inhibition. Based on the experimental design and measurements taken, which core factor would be used to select test chemical compounds for further testing of Notch Inhibition?
A. Structure of the compound and compounds with IC₅₀ values ranging between 0.73 and 4μM.
B. Compounds with a decrease in the normalised firefly/Renilla luciferase ratio in a dose-dependent manner compared to DMSO controls and compounds with an increase in Renilla luciferase signal
C. Compounds with decreased firefly luciferase signal below 70% and compounds with decreased renilla luciferase signal below 70%
D. Compound with the smallest size and compounds with a high bioavailability.
|
A. Structure of the compound and compounds with IC₅₀ values ranging between 0.73 and 4μM.
|
- The Notch signalling pathway is a cell-cell communication system required for differentiation and homeostasis of most tissues and organs. Notch receptors and ligands are highly evolutionarily conserved, and Notch signalling operates in most, if not all, multicellular organisms.
- Small-molecule inhibitors have been developed, including RIN1, CB-103, NADI-351 and Z271-0326 which disrupt the Notch transcriptional complex.
|
[{"label":"RBK Item","value":"- The Notch signalling pathway is a cell-cell communication system required for differentiation and homeostasis of most tissues and organs. Notch receptors and ligands are highly evolutionarily conserved, and Notch signalling operates in most, if not all, multicellular organisms."},{"label":"Title","value":"Notch signalling in context"},{"label":"URL","value":"https://www.nature.com/articles/nrm.2016.94"},{"label":"Date","value":"August 10, 2016"},{"label":"Justification (\"Paywalled\", \"OA\", \"Other (justify)\")","value":"Paywalled"},{"label":"RBK Item","value":"- Small-molecule inhibitors have been developed, including RIN1, CB-103, NADI-351 and Z271-0326 which disrupt the Notch transcriptional complex."},{"label":"Title","value":"Disruption of NOTCH signaling by a small molecule inhibitor of the transcription factor RBPJ"},{"label":"URL","value":"https://www.nature.com/articles/s41598-019-46948-5"},{"label":"Date","value":"July 25, 2019"},{"label":"Justification (\"Paywalled\", \"OA\", \"Other (justify)\")","value":"OA"}]
|
Biology
|
Cancer immunotherapy
|
MCQ
|
Multi-parametric profiling of IL-7-augmented GD2.CART products in a phase 1 clinical trial
|
https://www.cell.com/iscience/fulltext/S2589-0042(25)01941-8
|
November 21, 2025
|
Among ten clinical CAR T cell products (from ten different patients with refractory diffuse midline glioma or other GD2-positive high-grade brain tumors), three contained anti-GD2 chimeric antigen receptor alone (group 1), and 7 contained anti-GD2 CAR co-expressed with a constitutively active IL-7 cytokine receptor C7R (group 2). The functional phenotype and cytotoxicity of these 10 different products were assessed by flow cytometry and a microscopy-based killing assay, respectively. For the phenotype assessment, CAR T cells were stimulated by a GD2-positive cell line (12h co-icubation at a 1:1 cell ratio), and then surface and intracellular markers, including CD154, CD26, CD103, BCL2, TIGIT, and GzmB, were measured. For cytotoxicity measurement, CAR T cells (effector cells) were co-cultured with GFP-positive GD2-positive cell line (target cells) at different effector-to-target ratios. The results of both experiments were integrated to compare multiple parameters defining the functionality of these two different types of products. The studied variables for group 1 and 2 were the percentage of cells expressing surface markers CD154, CD103, and CD26, assessed by flow cytometry; intracellular expression (% of positive cells) of granzyme B (GzmB) and Bcl-2, assessed by flow cytometry; and decrease in GFP+ target cell area (proportional to target cell death and therefore to CAR T cell cytotoxicity) assessed by live imaging microscopy.
|
1. Percent of cells expressing surface markers CD154, CD103, CD26, assessed for both treatment goups by flow cytometry.
2. Intracellular expression (% of positive cells) of granzyme B (GzmB) and Bcl-2, as assessed for both treatment groups by flow cytometry.
3. Decrease in GFP+ target cell area (proportional to target cell death and therefore to CAR T cell cytotoxicity) as assessed for both treatment groups by live imaging microscopy.
|
GD2-specific CAR T cells (group 1) and GD2-specific CAR T cells co-expressing constitutively active IL7Ra (group 2) were compared in terms of infiltration, activation, cytotoxicity, and killing potential based on the flow cytometry and killing assay results. Which of the following outcomes is most likely?
A) Group 1 demonstrated a superior killing compared to group 2, while other determinants were comparable between the two groups.
B) Group 1 exhibited superior killing, cytotoxicity, infiltration, and activation potential, and higher TIGIT expression as compared to group 2.
C) Cytotoxicity, activation, and killing potential were elevated in group 2, while TIGIT expression was higher in group 1.
D) All listed parameters were higher in group 2 as compared to group 1.
|
D) All listed parameters were higher in group 2 as compared to group 1.
|
- GD2-directed CARTs show promise for treating diffuse midline glioma and other GD2-expressing brain tumors, though their efficacy is challenged by the immunosuppressive tumor microenvironment and poor T cell persistence.
- A constitutively active IL-7 receptor (C7R) was implemented that enhances CART survival, metabolic fitness, and antitumor activity by activating IL-7-independent STAT5 signaling and overcomes cytokine deprivation at tumor sites without affecting bystander immune cells.
- Preclinical studies demonstrated enhanced CART proliferation, persistence, and tumor-killing capacity by the C7R, even in cytokine-depleted environments.
- Higher GrzB and CD26 expression suggests higher T cell cytotoxicity.
- Higher BCL-2, CD26, and CD154 expression indicates higher potential for T cell activation.
- Elevated TIGIT is associated with higher resilience, while CD26 and CD103 suggest a role in T cell infiltration into tissues.
|
[{"label":"RBK Item","value":"GD2-directed CARTs show promise for treating diffuse midline glioma and other GD2-expressing brain tumors, though their efficacy is challenged by the immunosuppressive tumor microenvironment and poor T cell persistence."},{"label":"Title","value":"CAR T Cells for Solid Tumors: New Strategies for Finding, Infiltrating, and Surviving in the Tumor Microenvironment"},{"label":"URL","value":"https://www.frontiersin.org/journals/immunology/articles/10.3389/fimmu.2019.00128/full"},{"label":"Date","value":"Feb 04, 2019"},{"label":"Justification (\"Paywalled\", \"OA\", \"Other (justify)\")","value":"OA"},{"label":"RBK Item","value":"A constitutively active IL-7 receptor (C7R) was implemented that enhances CART survival, metabolic fitness, and antitumor activity by activating IL-7-independent STAT5 signaling and overcomes cytokine deprivation at tumor sites without affecting bystander immune cells."},{"label":"Title","value":"Constitutive Signaling from an Engineered IL7 Receptor Promotes Durable Tumor Elimination by Tumor-Redirected T Cells"},{"label":"URL","value":"https://aacrjournals.org/cancerdiscovery/article/7/11/1238/6513/Constitutive-Signaling-from-an-Engineered-IL7"},{"label":"Date","value":"Nov 01, 2017"},{"label":"Justification (\"Paywalled\", \"OA\", \"Other (justify)\")","value":"OA"},{"label":"RBK Item","value":"Preclinical studies demonstrated enhanced CART proliferation, persistence, and tumor-killing capacity by the C7R, even in cytokine-depleted environments. "},{"label":"Title","value":"Phase I Trial of GD2.CART Cells Augmented With Constitutive Interleukin-7 Receptor for Treatment of High-Grade Pediatric CNS Tumors"},{"label":"URL","value":"https://ascopubs.org/doi/10.1200/JCO.23.02019"},{"label":"Date","value":"May 21, 2024"},{"label":"Justification (\"Paywalled\", \"OA\", \"Other (justify)\")","value":"OA"}]
|
Biology
|
Immunology
|
MCQ
|
Albumin-STING Nanoagonist Reprograms HSPCs to Antitumor Neutrophils Enhancing MHC I–Mediated CD8⁺ T Cell Immunity
|
https://www.biorxiv.org/content/10.1101/2025.09.02.673154v2
|
Oct 24, 2025
|
Researchers compared different inflammatory cytokines (TNF-α, IFN-β, IFN-γ, IL-6) on the expansion of hematopoietic stem/progenitor cells (HSPCs). For this purpose, bone marrow cells from C57BL/6J mice were isolated. Bone marrow single-cell suspensions were enriched for lineage-negative (Lin⁻) cells using a biotin-conjugated lineage panel (BioLegend) and magnetic separation, then stained with fluorophore-conjugated antibodies. LSK (Lin-Sca-1+c-Kit+) HSPCs were sorted using a flow cytometry sorter and cultured in StemSpan with 50 ng/mL SCF (BioLegend) at 2×10⁴ cells/well in 96 well U-bottom plates. Cells were treated with 10 ng/mL cytokines for 3 days. After treatment, the cells were analyzed with flow cytometry to compare the HSPC expansion by each inflammatory cytokine. The measurements taken were the expression of Sca-1 and c-Kit in Lin- population and the percentage of LSK cells in Lin- population, in each condition.
|
- The expression of Sca-1 and c-Kit in Lin- population in each condition, using flow cytometry.
- Percentage of LSK cells in Lin- population in each condition, using flow cytometry.
|
Expansion of bone marrow HSPCs by 10ng/mL inflammatory cytokines TNF-α, IFN-β, IFN-γ, or IL-6 were compared. LSK cells from bone marrow were treated with each cytokine for 3 days, respectively. After that, cells from each culture condition were collected and analyzed with a flow cytometry analyzer to measure the percentage of LSK cells in Lin- cell population. Which inflammatory cytokine do you predict to induce highest percentage of LSK cells in Lin- cells?
A) IFN-γ
B) IL-6
C) IFN-β
D) TNF-α
|
B) IL-6
|
- The STING pathway activation triggers phosphorylation of TBK1–IRF3 and NF-κB to induce interferons and proinflammatory cytokines such as TNF-a and IL-6, thereby promoting immunity.
- STING expression is higher in HSPCs than in their differentiated immune progeny.
|
[{"label":"RBK Item","value":"The STING pathway activation triggers phosphorylation of TBK1–IRF3 and NF-κB to induce interferons and proinflammatory cytokines such as TNF-a and IL-6, thereby promoting immunity."},{"label":"Title","value":"STING regulates intracellular DNA-mediated, type I interferon-dependent innate immunity"},{"label":"URL","value":"https://pmc.ncbi.nlm.nih.gov/articles/PMC4664154/"},{"label":"Date","value":"Sep 23, 2009"},{"label":"Justification (\"Paywalled\", \"OA\", \"Other (justify)\")","value":"OA"},{"label":"RBK Item","value":"STING expression is higher in HSPCs than in their differentiated immune progeny."},{"label":"Title","value":"STING activation in TET2-mutated hematopoietic stem/progenitor cells contributes to the increased self-renewal and neoplastic transformation"},{"label":"URL","value":"https://pmc.ncbi.nlm.nih.gov/articles/PMC10681905/"},{"label":"Date","value":"Oct 10, 2023"},{"label":"Justification (\"Paywalled\", \"OA\", \"Other (justify)\")","value":"OA"}]
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Biology
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Animal behavior
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MCQ
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Specific Wavelengths of Light Modulate Honey Bee Locomotor Activity
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https://www.biorxiv.org/content/10.1101/2025.10.22.683871v1
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October 23, 2025
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Researchers investigated how exposure to specific wavelengths, as well as their combinations, affects the locomotor activity (LMA) of honey bee (Apis mellifera). Returning forager bees were obtained from two colonies located on the Middle East Technical University campus. They utilized light-emitting diodes (LEDs) with peak wavelengths of 528 nm (green), 447 nm (blue), 372 nm (UV), and 849 nm (infrared - IR) (verified using a spectrometer). The LEDs were connected to DC power supplies, whose current and voltage were regulated to deliver a consistent irradiance of 12 µW/cm². Bees were placed in glass tubes (16mm diameter x 100 mm length) with a 2 mm-diameter hole in the middle to allow ventilation. The mouth of each tube was covered with a lid containing fondant sugar and cheesecloth, allowing the bees to feed while preventing them from sticking to the sugar. The tubes were placed horizontally, side by side, inside the climate chamber, set to 32 °C and 60 % relative humidity. A webcam was placed inside the chamber, parallel to the tubes, and at a distance that covered all tubes. Eight separate experiments were conducted with only green, blue, UV, and combinations of green-blue, green-UV, blue-UV, green-blue-UV, and only IR (dark for bees) LEDs on. The bees were replaced at the beginning of each experiment, and 32 were used in each. The experiments started at 7:00 pm and lasted 24 hours. Activity counts were extracted using video recordings, which were processed with the Api-TRACE Video Processing Module (similar to methods of counting the passage of bees across the midpoint of the tubes) by tracking the position of the bee continuously (shift from one region to another). Researchers used the Kruskal-Wallis test followed by a post-hoc Dunn test to assess differences in total 24-hour LMA across light exposure groups.
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- Honey bees' locomotor activity level (based on activity counts measured via Api-TRACE Video Processing module), for each LED wavelength treatments: only green, blue, UV, and combinations of green-blue, green-UV, blue-UV, green-blue-UV, and only IR/dark control for 24 hours.
|
Researchers investigated how exposure to specific wavelengths, as well as their combinations, affects the locomotor activity of honey bee (Apis mellifera). Returning forager bees were obtained from two colonies located on the Middle East Technical University campus. They utilized light-emitting diodes (LEDs) (consistent irradiance of 12 µW/cm²) with peak wavelengths of 528 nm (green), 447 nm (blue), 372 nm (ultraviolet; UV), and 849 nm (infrared; IR). Bees were placed in glass tubes (16mm diameter x 100 mm length) with a 2 mm-diameter hole in the middle to allow ventilation. The mouth of each tube was covered with a lid containing fondant sugar and cheesecloth. The tubes were placed horizontally, side by side, inside the climate chamber, set to 32 °C and 60 % relative humidity. A webcam was placed inside the chamber, parallel to the tubes, and at a distance that covered all tubes. Eight separate experiments (32 bees per experiment) were conducted with green only, blue only, UV only, and combinations of green-blue, green-UV, blue-UV, green-blue-UV, and only IR (dark control) LEDs on. The experiments started at 7:00 pm and lasted 24 hours. Activity counts were extracted using video recordings, which were processed with the Api-TRACE Video Processing Module by tracking the position of the bee continuously (shift from one region to another). Which of the following outcomes is most likely?
A. Infrared exposure led to the lowest activity levels.
B. Blue-UV exposure led to the lowest activity levels observed.
C. UV-only exposure led to the lowest activity levels observed.
D. Green light exposure led to the lowest activity levels observed.
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B. Blue-UV exposure led to the lowest activity levels observed.
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- Color vision enables bees to recognize flowers, navigate, and forage for food
- Bees possess three types of photoreceptors in their retina, with absorption peaks at 344 nm (UV or short type), 436 nm (blue or medium type), and 544 nm (green or long type)
- The anterior optic tube receives chromatic input from the lobula and processes UV, blue, and green light separately in distinct subunits. Green light dominantly activates both the dorsal and ventral lobes, blue light activates the dorsal lobe, and UV light activates the ventral lobe.
- The anterior optic tube sends projections to higher-level brain centers such as the lateral protocerebrum (LP) and the central complex (CC). The LP integrates visual information, with anterior LP neurons being primarily color-sensitive, while the CC regulates movement and orientation based on processed chromatic input.
- Light is a strong environmental component that affects bees' locomotor activity
|
[{"label":"RBK Item","value":"Color vision enables bees to recognize flowers, navigate, and forage for food"},{"label":"Title","value":"Mechanisms, functions and ecology of colour vision in the honeybee"},{"label":"URL","value":"https://link.springer.com/article/10.1007/s00359-014-0915-1"},{"label":"Date","value":"May 15, 2014"},{"label":"Justification (\"Paywalled\", \"OA\", \"Other (justify)\")","value":"OA"},{"label":"RBK Item","value":"Bees possess three types of photoreceptors in their retina, with absorption peaks at 344 nm (UV or short type), 436 nm (blue or medium type), and 544 nm (green or long type)"},{"label":"Title","value":"Colour receptors in the bee eye — Morphology and spectral sensitivity"},{"label":"URL","value":"https://link.springer.com/article/10.1007/BF00625437"},{"label":"Date","value":"January, 1976"},{"label":"Justification (\"Paywalled\", \"OA\", \"Other (justify)\")","value":"Paywalled"},{"label":"RBK Item","value":"The anterior optic tube receives chromatic input from the lobula and processes UV, blue, and green light separately in distinct subunits. Green light dominantly activates both the dorsal and ventral lobes, blue light activates the dorsal lobe, and UV light activates the ventral lobe."},{"label":"Title","value":"Chromatic processing in the anterior optic tubercle of the honey bee brain"},{"label":"URL","value":"https://www.jneurosci.org/content/33/1/4"},{"label":"Date","value":"January 2, 2013"},{"label":"Justification (\"Paywalled\", \"OA\", \"Other (justify)\")","value":"OA"},{"label":"RBK Item","value":"The anterior optic tube sends projections to higher-level brain centers such as the lateral protocerebrum (LP) and the central complex (CC). The LP integrates visual information, with anterior LP neurons being primarily color-sensitive, while the CC regulates movement and orientation based on processed chromatic input."},{"label":"Title","value":"Chromatic processing in the anterior optic tubercle of the honey bee brain"},{"label":"URL","value":"https://www.jneurosci.org/content/33/1/4"},{"label":"Date","value":"January 2, 2013"},{"label":"Justification (\"Paywalled\", \"OA\", \"Other (justify)\")","value":"OA"},{"label":"RBK Item","value":"Light is a strong environmental component that affects bees' locomotor activity"},{"label":"Title","value":"Light and temperature entrainment of a locomotor rhythm in honeybees"},{"label":"URL","value":"https://resjournals.onlinelibrary.wiley.com/doi/10.1111/j.1365-3032.1993.tb00599.x"},{"label":"Date","value":"September, 1993"},{"label":"Justification (\"Paywalled\", \"OA\", \"Other (justify)\")","value":"OA"}]
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Biology
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Cancer Biology
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Free-Format Question
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Artesunate induces ferroptosis in osteosarcoma through NCOA4‑mediated ferritinophagy
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https://pubmed.ncbi.nlm.nih.gov/40168090/
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April 01, 2025
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Researchers tested the effect of Artesunate(ART) on Osteosarcoma (OS) cell proliferation. To do this, Osteoblast hFOB1.19 (American Type Culture Collection ATCC), MG63 and 143B cell lines were used. The cells were cultured in Dulbecco's Modified Eagle Medium (DMEM) (Vivacell Bioscience, Shanghai, China). Complete culture medium comprised 1% penicillin (Vivacell, Shanghai, China) and 10% fetal bovine serum (FBS) (Thermo Fisher, Shanghai, China) was added to the cell culture, and cells were maintained at 5% CO2 and 37°C. The cells (MG63, 143B, and hFOB 1.19) were next treated without or with ART (concentrations of 0, 5, 10, 20, 30, 40, 60, 80 and 100 μM) for 24, 48, or 72 h. Next, the drug-containing medium was removed, and a CCK-8 solution was diluted, and the cells were incubated in the solution for 2h, after which absorbance was measured at 450 nm by an enzyme-labelled apparatus.
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- Absorbance at 450nm of MG63, 143B, and hFOB 1.19 cells treated without or with ART (concentrations of 0, 5, 10, 20, 30, 40, 60, 80 and 100 μM) for 24, 48, or 72 h.
- Cell viability rate (%) of MG63, 143B, and hFOB 1.19 cells treated without or with ART (concentrations of 0, 5, 10, 20, 30, 40, 60, 80 and 100 μM) for 24, 48, or 72 h.
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Researchers tested the effect of Artesunate(ART) on Osteosarcoma (OS) cell proliferation. To do this, Osteoblast hFOB1.19 (American Type Culture Collection ATCC), MG63 and 143B cell lines were used. The cells were cultured in Dulbecco's Modified Eagle Medium (DMEM) (Vivacell Bioscience, Shanghai, China). Complete culture medium comprised 1% penicillin (Vivacell, Shanghai, China) and 10% fetal bovine serum (FBS) (Thermo Fisher, Shanghai, China) was added to the cell culture, and cells were maintained at 5% CO2 and 37°C. The cells (MG63, 143B, and hFOB 1.19) were next treated without or with ART (concentrations of 0, 5, 10, 20, 30, 40, 60, 80 and 100 μM) for 24, 48, or 72 h. Next, the drug-containing medium was removed, and a CCK-8 solution was diluted, and the cells were incubated in the solution for 2h, after which absorbance was measured at 450 nm by an enzyme-labelled apparatus. If the cell viability rate was measured for the cell lines after ART treatment, which cell line (if none of the cell lines had any viable cells after treatment, kindly say so) will have viable cells after 72 h of treatment with 100 μM ART?
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hFOB 1.19 cells had viable cells after 72 hours of treatment with 100μM ART
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- Osteosarcoma (OS) is the most prevalent primary bone malignancy of mesenchymal origin in children and adolescents, with 3.4 cases per million people worldwide.
- Artesunate (ART) is a new treatment for severe malaria.
- ART could inhibit the proliferation, migration, and invasion of tumour cells by regulating gene expression and signalling pathways, thus playing a therapeutic role in the occurrence and development of various malignant tumours.
|
[{"label":"RBK Item","value":"Osteosarcoma (OS) is the most prevalent primary bone malignancy of mesenchymal origin in children and adolescents, with 3.4 cases per million people worldwide."},{"label":"Title","value":"METTL14-mediated epitranscriptome modification of MN1 mRNA promote tumorigenicity and all-trans-retinoic acid resistance in osteosarcoma"},{"label":"URL","value":"https://www.thelancet.com/journals/ebiom/article/PIIS2352-3964(22)00323-1/fulltext"},{"label":"Date","value":"July 7, 2022"},{"label":"Justification (\"Paywalled\", \"OA\", \"Other (justify)\")","value":"OA"},{"label":"RBK Item","value":"Artesunate (ART) is a new treatment for severe malaria."},{"label":"Title","value":"Malaria Surveillance — United States, 2017"},{"label":"URL","value":"https://www.cdc.gov/mmwr/volumes/70/ss/ss7002a1.htm"},{"label":"Date","value":"March 19, 2017"},{"label":"Justification (\"Paywalled\", \"OA\", \"Other (justify)\")","value":"OA"},{"label":"RBK Item","value":"ART could inhibit the proliferation, migration, and invasion of tumour cells by regulating gene expression and signalling pathways, thus playing a therapeutic role in the occurrence and development of various malignant tumours."},{"label":"Title","value":"Artesunate Exhibits Synergy With Cisplatin and Cytotoxicity for Upper Tract and Bladder Urothelial Carcinoma Cells"},{"label":"URL","value":"https://pubmed.ncbi.nlm.nih.gov/36854526/"},{"label":"Date","value":"March, 2023"},{"label":"Justification (\"Paywalled\", \"OA\", \"Other (justify)\")","value":"Paywalled"}]
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Biology
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Immunology
|
Free-Format Question
|
SARS-CoV-2 mRNA vaccines sensitize tumours to immune checkpoint blockade
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https://pubmed.ncbi.nlm.nih.gov/41125896/
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October 22, 2025
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Tumour-bearing mice (male and female; background of C57BL/6 and Rigi-knockout mice (C57BL/6NJ-Rigiem1(IMPC)J/Mmjax)) were implanted subcutaneously (s.c.) with 50,000 B16F0 or 10^6 B16F10-OVA melanoma cells in the right flank. From this, 8 treatment groups were made, namely: Untreated group (mice received no treatments), PD-L1 group (mice received 400 μg of Anti-PD-L1 (Bio X Cell, BE0101) checkpoint inhibitor per mouse as initial does followed by 200 μg per mouse twice a week till endpoint), RNA-LNP group (vaccinated intramuscularly with 25 μg per dose of RNA-LNP (RNA of SARS-CoV-2 spike coding sequence with K986P and V987P mutations encapsulated in lipid nanoparticles)), anti-IFNAR group (mice received 500 μg of anti-mouse IFNα receptor (aIFNAR1, Bio X Cell, BE0241) antibodies per mouse as initial does followed by 250 μg per mouse twice a week till endpoint), anti-IL-1R group (mice received 500 μg of anti-mouse IL-1R (Bio X Cell, BE0256) antibodies per mouse as initial does followed by 250 μg per mouse twice a week till endpoint), RNA-LNP + PD-L1 group (vaccinated intramuscularly with 25 μg per dose of RNA-LNP plus same treatment regime of PD-L1 group), RNA-LNP + PD-L1 + anti-IFNAR group (vaccinated intramuscularly with 25 μg per dose of RNA-LNP plus same treatment regime of PD-L1 and anti-IFNAR group), RNA-LNP + PD-L1 + anti-IL-1R group (vaccinated intramuscularly with 25 μg per dose of RNA-LNP plus same treatment regime of PD-L1 and anti-IL-1R group). For all groups, LMW poly(I:C) (InvivoGen, tlrl-picw) was administered intramuscularly with 25 μg per mouse for two doses. Tumour size (in mm^3) was measured at a frequency of three times a week, starting on day 8 until more than 20% of mice reached the end point.
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- Triweekly tumour size (mm^3) of mice in the untreated group, PD-L1 group, RNA-LNP group, anti-IFNAR group, anti-IL-1R group, RNA-LNP + PD-L1 group, RNA-LNP + PD-L1 + anti-IFNAR group and RNA-LNP + PD-L1 + anti-IL-1R group, starting from day 8 until more than 20% of mice reached the end point.
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Tumour-bearing mice (male and female; background of C57BL/6 and Rigi-knockout mice (C57BL/6NJ-Rigiem1(IMPC)J/Mmjax)) were implanted subcutaneously (s.c.) with 50,000 B16F0 or 10^6 B16F10-OVA melanoma cells in the right flank. From this, 8 treatment groups were made, namely: Untreated group (mice received no treatments), PD-L1 group (mice received 400 μg of Anti-PD-L1 (Bio X Cell, BE0101) checkpoint inhibitor per mouse as initial does followed by 200 μg per mouse twice a week till endpoint), RNA-LNP group (vaccinated intramuscularly with 25 μg per dose of RNA-LNP (RNA of SARS-CoV-2 spike coding sequence with K986P and V987P mutations encapsulated in lipid nanoparticles)), anti-IFNAR group (mice received 500 μg of anti-mouse IFNα receptor (aIFNAR1, Bio X Cell, BE0241) antibodies per mouse as initial does followed by 250 μg per mouse twice a week till endpoint), anti-IL-1R group (mice received 500 μg of anti-mouse IL-1R (Bio X Cell, BE0256) antibodies per mouse as initial does followed by 250 μg per mouse twice a week till endpoint), RNA-LNP + PD-L1 group (vaccinated intramuscularly with 25 μg per dose of RNA-LNP plus same treatment regime of PD-L1 group), RNA-LNP + PD-L1 + anti-IFNAR group (vaccinated intramuscularly with 25 μg per dose of RNA-LNP plus same treatment regime of PD-L1 and anti-IFNAR group), RNA-LNP + PD-L1 + anti-IL-1R group (vaccinated intramuscularly with 25 μg per dose of RNA-LNP plus same treatment regime of PD-L1 and anti-IL-1R group). For all groups, LMW poly(I:C) (InvivoGen, tlrl-picw) was administered intramuscularly with 25 μg per mouse for two doses. If tumour size is measured at a frequency of three times a week, starting on day 8, until more than 20% of mice reach the end point in all treatment groups, which two groups would have the most significant reduction in tumour size?
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The two combination therapy group of RNA-LNP + PD-L1 and RNA-LNP + PD-L1 + anti-IL-1R strongly inhibited tumour growth and showed the lowest tumour size.
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- Systemic administration of highly immunogenic mRNA nanoparticles induces a viraemia-like cytokine/chemokine response that resets the systemic and intratumoural immune milieu, sensitizing resistant tumours to ICIs.
- COVID-19 mRNA vaccines also induce robust stimulation of cytokine secretion and tumours are sometimes resolved after COVID-19 mRNA vaccine administration.
|
[{"label":"RBK Item","value":"- Systemic administration of highly immunogenic mRNA nanoparticles induces a viraemia-like cytokine/chemokine response that resets the systemic and intratumoural immune milieu, sensitizing resistant tumours to ICIs."},{"label":"Title","value":"Personalized tumor rna loaded lipid-nanoparticles prime the systemic and intratumoral milieu for response to cancer immunotherapy."},{"label":"URL","value":"https://pmc.ncbi.nlm.nih.gov/articles/PMC6597257/"},{"label":"Date","value":"September 27, 2018"},{"label":"Justification (\"Paywalled\", \"OA\", \"Other (justify)\")","value":"OA"},{"label":"RBK Item","value":"- COVID-19 mRNA vaccines also induce robust stimulation of cytokine secretion and tumours are sometimes resolved after COVID-19 mRNA vaccine administration."},{"label":"Title","value":"Spontaneous tumor regression following COVID-19 vaccination."},{"label":"URL","value":"https://jitc.bmj.com/content/10/3/e004371"},{"label":"Date","value":"March 3, 2022"},{"label":"Justification (\"Paywalled\", \"OA\", \"Other (justify)\")","value":"OA"}]
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Biology
|
Neurobiology / Immunology
|
Free-Format Question
|
Dual role of Lyz2-positive myeloid cells in traumatic brain injury: acute anti-inflammatory effects vs. chronic neurological deterioration
|
https://www.frontiersin.org/journals/cellular-neuroscience/articles/10.3389/fncel.2025.1642410/full
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October 6, 2025
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The authors investigated the impact of myeloid depletion on neuronal survival in Lyz2-IRES-DTREGFP mice after controlled cortical impact (CCI) injury (TBI group), compared with mice at the same conditions but with Diphtheria toxin (DT) administration (DT+TBI group). Prior to the experiment, the DT-TBI group was administered 0.15 mg/mL of DT (25 ng/g) in saline solution for three consecutive days before the CCI. All groups were anesthetized with a cocktail of ketamine (80 mg/kg)/xylazine (10 mg/kg), and a controlled cortical impact injury (CCI) was performed, where a circular craniotomy was performed on the skull located in the hippocampal region, they were positioned on a PSI-IH impactor, and an impact force of 100 kDynes was delivered to include a brain contusion (confirmed by red impact site on the cerebral surface and slight hemorrhaging). 28 days post-CCI, mice were perfusion-fixed, and brain tissue sections of 10 μm thickness were prepared for Nissl staining to quantify the number of surviving neurons (counted in matched fields; three consecutive sections per animal).
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- Quantification of surviving neurons in Lyz2-IRES-DTREGFP mice with or without diphtheria toxin after controlled cortical impact injury (28 days after) as viewed by Nissl staining.
|
The authors investigated the impact of myeloid depletion on neuronal survival in Lyz2-IRES-DTREGFP mice after controlled cortical impact (CCI) injury (traumatic brain injury; TBI group), compared with mice at the same conditions but with Diphtheria toxin (DT) administration (DT+TBI group). Prior to the experiment, the DT-TBI group was administered 0.15 mg/ml of DT (25 ng/g) in saline solution for three consecutive days prior to the CCI. All groups were anesthetized with a cocktail of ketamine (80 mg/kg)/xylazine (10 mg/kg), and a controlled cortical impact injury (CCI) was performed, where a circular craniotomy was performed on the skull located in the hippocampal region, they were positioned on a PSI-IH impactor, and an impact force of 100 kDynes was delivered to include a brain contusion (confirmed by red impact site on the cerebral surface and slight hemorrhaging). 28 days post-CCI, mice were perfusion-fixed, and brain tissue sections of 10 μm thickness were prepared for Nissl staining to quantify the number of surviving neurons.
Predict the relative difference (more, fewer, or similar) in surviving neuron counts in the DT + TBI compared to TBI mouse groups following controlled cortical impact injury.
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The DT + TBI group showed fewer surviving neurons than the TBI group.
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- Myeloid cells constitute the primary cellular component of the innate immune system and play a critical role in the response to central nervous system (CNS) injury.
- Lyz2-IRES-DTREGFP mice were generated by enabling specific expression of DTR (diphtheria toxin receptor) in myeloid cells, therefore, intraperitoneal injection of diphtheria toxin (DT) induces cell-specific ablation, as DT binds to the DTR and exerts cytotoxic effects, leading to targeted cell death.
|
[{"label":"RBK Item","value":"- Myeloid cells constitute the primary cellular component of the innate immune system and play a critical role in the response to central nervous system (CNS) injury. "},{"label":"Title","value":"The Nature of Myeloid-Derived Suppressor Cells in the Tumor Microenvironment"},{"label":"URL","value":"https://pmc.ncbi.nlm.nih.gov/articles/PMC4775398/"},{"label":"Date","value":"March 1, 2017"},{"label":"Justification (\"Paywalled\", \"OA\", \"Other (justify)\")","value":"OA"},{"label":"RBK Item","value":"- Lyz2-IRES-DTREGFP mice were generated by enabling specific expression of DTR (diphtheria toxin receptor) in myeloid cells, therefore, intraperitoneal injection of diphtheria toxin (DT) induces cell-specific ablation, as DT binds to the DTR and exerts cytotoxic effects, leading to targeted cell death.\n"},{"label":"Title","value":"A Transgenic Mouse Model of Inducible Macrophage Depletion"},{"label":"URL","value":"https://ajp.amjpathol.org/article/S0002-9440(10)60530-5/fulltext"},{"label":"Date","value":"July 2009"},{"label":"Justification (\"Paywalled\", \"OA\", \"Other (justify)\")","value":"OA"}]
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Biology
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Animal Behavior
|
Free-Format Question
|
Access to running wheels decreases social motivation in adult C57BL/6J female mice
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https://www.biorxiv.org/content/10.1101/2025.09.25.678626v1
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September 25, 2025
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Researchers investigated whether home cage access to running wheels impacts social behaviors of adult, group-housed female C57BL/6J mice during same-sex interactions. At weaning (postnatal day 21), female siblings were assigned to either hut condition (n=19; paper hut, standard enrichment, no running wheel) or wheel condition (n=16; combined shelter/running wheel, standard enrichment, no paper hut). Mice were maintained on 12h:12h reversed light/dark cycle with ad libitum food and water.
After 5 weeks (at 8 weeks of age), each subject female was given a 10-minute social interaction test with a novel, group-housed adult female. The subject's home cage was placed in a sound-attenuating chamber with infrared lighting and webcam recording, and the shelter (wheel or hut) was removed. Siblings were temporarily moved to another cage during testing.
Trained observers blinded to experimental group assignments used BORIS v.8.13 software to score total time (s) that the subject female spent engaged in social investigation of the novel female from webcam videos. Social investigation was defined as sniffing or following the novel female, including times of mutual social investigation (mutual sniffing and/or circling).
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- Total social investigation time (s) scored from webcam videos using BORIS v.8.13 software by trained observers; measured for wheel condition vs. hut condition (n=19 hut, n=16 wheel)
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Researchers investigated whether home cage access to running wheels affects social behavior in adult female mice during same-sex interactions. Group-housed female siblings (C57BL/6J) were assigned at weaning to either wheel condition (with running wheel) or hut condition (with paper hut), maintained for 5 weeks, then given a 10-minute social interaction test with a novel female at 8 weeks of age. Trained observers scored total time that subject females spent engaged in social investigation of the novel female. How did social investigation time compare between the wheel and hut conditions?
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Female subjects in the wheel condition spent significantly less time engaged in social investigation compared to female subjects in the hut condition.
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- The most common form of exercise provided to laboratory rodents is voluntary wheel running, in which rodents are given free access to a running wheel in their home environment.
- Wheel running has been shown to attenuate the effects of chronic social defeat stress on sociability and aggression in male mice.
- Wheel running attenuates the effects on sociability of inescapable tail shock in female rats.
- Wheel running reduces the effects of chronic social isolation on sociability and aggression in mice.
- Wheel running reduces the severity of anxiety-like and depressive-like behaviors in rodents subjected to a combination of social isolation and chronic mild stress.
|
[{"label":"RBK Item","value":"The most common form of exercise provided to laboratory rodents is voluntary wheel running, in which rodents are given free access to a running wheel in their home environment"},{"label":"Title","value":"Voluntary wheel running: patterns and physiological effects in mice"},{"label":"URL","value":"https://www.scielo.br/j/bjmbr/a/kCDDvjgLp5p8gRN3PhJ3jKz/?lang=en"},{"label":"Date","value":"December, 2018"},{"label":"Justification (\"Paywalled\", \"OA\", \"Other (justify)\")","value":"OA"},{"label":"RBK Item","value":"Wheel running has been shown to attenuate the effects of chronic social defeat stress on sociability and aggression in mice."},{"label":"Title","value":"Voluntary wheel running promotes resilience to chronic social defeat stress in mice: a role for nucleus accumbens ΔFosB"},{"label":"URL","value":"https://www.nature.com/articles/s41386-018-0103-z"},{"label":"Date","value":"May 24, 2018"},{"label":"Justification (\"Paywalled\", \"OA\", \"Other (justify)\")","value":"OA"},{"label":"RBK Item","value":"Wheel running attenuates the effects on sociability of inescapable tail shock in female rats."},{"label":"Title","value":"Female rats are more responsive than are males to the protective effects of voluntary physical activity against the behavioral consequences of inescapable stress"},{"label":"URL","value":"https://www.tandfonline.com/doi/full/10.1080/10253890.2023.2245492"},{"label":"Date","value":"August 23, 2023"},{"label":"Justification (\"Paywalled\", \"OA\", \"Other (justify)\")","value":"OA"},{"label":"RBK Item","value":"Wheel running reduces the effects of chronic social isolation on sociability and aggression in mice."},{"label":"Title","value":"Voluntary wheel running ameliorates abnormalities in social behavior induced by social isolation: Involvement of neural and neurochemical responses"},{"label":"URL","value":"https://www.sciencedirect.com/science/article/abs/pii/S0304394023001994"},{"label":"Date","value":"April 07, 2023"},{"label":"Justification (\"Paywalled\", \"OA\", \"Other (justify)\")","value":"Paywalled"},{"label":"RBK Item","value":"Wheel running reduces the severity of anxiety-like and depressive-like behaviors in rodents subjected to a combination of social isolation and chronic mild stress."},{"label":"Title","value":"Voluntary physical exercise protects against behavioral and endocrine reactivity to social and environmental stressors in the prairie vole"},{"label":"URL","value":"https://www.tandfonline.com/doi/full/10.1080/17470919.2017.1365761"},{"label":"Date","value":"August 18, 2017"},{"label":"Justification (\"Paywalled\", \"OA\", \"Other (justify)\")","value":"Paywalled"}]
|
Biology
|
Neurobiology and Nanobiotechnology
|
Numerical Values
|
Development and Evaluation of Indian Mustard Honey-Loaded Fast Dissolving PVA/AG Nanofibers for Enhanced Neuroprotection
|
https://pubs.acs.org/doi/full/10.1021/acsomega.5c05524
|
October 1, 2025
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Researchers evaluated the neuroprotective effects of MH (mustard honey) loaded poly(vinyl alcohol) (PVA)/acacia gum (AG) nanofibers in HT-22 neuronal cells using an H2O2-induced oxidative stress survivability assay. PVA was dissolved in water to 8% (w/v) solid concentration and stirred for 2-3 hours. Afterwards, a 2% (w/v) AG solution was mixed with a clear PVA solution and stirred for an additional 3 hours. Additionally, solutions of PVA/AG containing MH at concentrations of 5, 10, 15, and 20% (w/v) were prepared overnight by stirring at room temperature to semiturbid conditions. Pristine PVA/AG solutions were prepared as a blank sample, without honey. PVA and AG were fixed at 8 and 2% concentrations, respectively, for all systems. After solution prep, they were electrospun using ESPIN-NANO electrospinning equipment. Samples were loaded into a 10 mL syringe and horizontally loaded into the pump. Voltage was set to 18 kV. The electrospinning solution was pumped through the needle using a syringe pump at a stable flow rate (0.7 mL/h) for pristine/blank PVA/AG solution, 1.2 mL/h for PVA/AG/MH (5, 10%), and 1.3 mL/h for PVA/AG/MH (15 and 20%). For the deposition of nanofibers, a metal plate covered with an aluminum foil sheet was placed 15 cm away from the needle (conditions were at ~25% humidity and ~20°C).
For the survivability assay, HT-22 cells were initially cultured in DMEM-HG (Dulbecco’s Modified Eagle’s Medium-High Glucose) with 10% fetal bovine serum, in a CO2 incubator with 5% CO2, at 37 °C. The extracts were prepared as follows: 5 mg of each nanofiber formulation: blank PVA/AG (without MH) or MH-loaded (5, 10, 15 and 20% w/v). They were suspended in 5 mL of culture medium and incubated (24 h at 37 °C). Cells were seeded in 96-well plates at a density of 5 × 10^3/well. At 70-80% confluency, the cells were treated with 100 μL of individual nanofiber extract and then incubated for 24 hours, followed by exposure to 500 H2O2 for 24h. Afterward, 10 μL of MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) reagent was added, and the mixture was incubated (4 h, in the dark, 37 °C). The resultant purple-colored formazan particles were dissolved in cell-grade DMSO. The optical density (OD570) was measured using a microplate spectrophotometer, and cell survivability (%) was calculated as (absorbance of treated H₂O₂-exposed cells/absorbance of untreated control) × 100.
|
- Cell survivability (% normalized to untreated control) across nanofiber formulations (blank PVA/AG, MH-loaded 5%, 10%, 15%, and 20% w/v) in HT-22 neuronal cells after H2O2 exposure, measured at 570 nm using a microplate spectrophotometer.
|
Researchers evaluated the neuroprotective effect of mustard honey (MH)-loaded poly(vinyl alcohol)/acacia gum (PVA/AG) nanofibers in HT-22 neuronal cells using an H2O2-induced oxidative stress survivability assay. The nanofibers were prepared by electrospinning PVA (8% w/v) and AG (2% w/v) solutions containing 5, 10, 15, or 20% (w/v) MH at 18 kV (0.7–1.3 mL/h flow rate, 15 cm tip-to-collector, ~25% humidity, and 20 °C). For testing, 5 mg of each nanofiber was incubated (5 mL DMEM-HG, 10% FBS, 24 h, 37 °C) to obtain extracts. HT-22 cells (5 × 10³/well, 96-well plate) were treated with 100 µL extract for 24 h, followed by 500 μM H2O2 for 24 h. Cell viability was then measured by MTT assay (10 µL MTT, 4 h, 37 °C, dark). Formazan crystals were dissolved in DMSO, and OD570 was recorded using a microplate spectrophotometer to calculate cell survival as % = (absorbance of treated H2O2-exposed cells/ absorbance of untreated control) x 100.
Predict the cell survival (%) of the 10% PVA/AG/MH group under H2O2 exposure.
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% Surviability= [60% - 80%] derived from 70% at 10% PVA/AG/MH + H2O2 condition. Note: SE reported +/- 10% applied.
|
- Mustard honey's (MH) high flavonoid and polyphenol content contributes to its neuroprotective and antioxidant properties.
- Poly(vinyl alcohol) (PVA) forms a fiber mesh providing an ideal neutral matrix and stability to the encapsulated compounds, ensuring their fast release without affecting its chemical properties.
- Acacia gum (AG), a natural polysaccharide collected from the acacia tree, was also used as a neutral stabilizing agent to the bioactive compounds, protecting and supporting their fast and controlled release. The water-soluble property of AG polysaccharide improves mucoadhesion, leading to better buccal absorption of drugs. Additionally, AG has intrinsic antioxidant activity that can synergistically enhance the antioxidant efficacy of an encapsulated drug.
|
[{"label":"RBK Item","value":"- Mustard honey's (MH) high flavonoid and polyphenol content contributes to its neuroprotective and antioxidant properties."},{"label":"Title","value":"Inhibitory effect of selected Indian honey on colon cancer cell growth by inducing apoptosis and targeting the β-catenin/Wnt pathway"},{"label":"URL","value":"https://pubs.rsc.org/en/content/articlelanding/2022/fo/d1fo03727g"},{"label":"Date","value":"July 14, 2022"},{"label":"Justification (\"Paywalled\", \"OA\", \"Other (justify)\")","value":"Paywalled"},{"label":"RBK Item","value":"- Poly(vinyl alcohol) (PVA) forms a fiber mesh providing an ideal neutral matrix and stability to the encapsulated compounds, ensuring their fast release without affecting its chemical properties."},{"label":"Title","value":"Encapsulation of vanillin/cyclodextrin inclusion complex in electrospun polyvinyl alcohol (PVA) nanowebs: Prolonged shelf-life and high temperature stability of vanillin"},{"label":"URL","value":"https://www.sciencedirect.com/science/article/abs/pii/S0308814612000738?via%3Dihub"},{"label":"Date","value":"August 1, 2012"},{"label":"Justification (\"Paywalled\", \"OA\", \"Other (justify)\")","value":"Paywalled"},{"label":"RBK Item","value":"- Acacia gum (AG), a natural polysaccharide collected from the acacia tree, was also used as a neutral stabilizing agent to the bioactive compounds, protecting and supporting their fast and controlled release. The water-soluble property of AG polysaccharide improves mucoadhesion, leading to better buccal absorption of drugs. Additionally, AG has intrinsic antioxidant activity that can synergistically enhance the antioxidant efficacy of an encapsulated drug. "},{"label":"Title","value":"Gum Arabic: A Commodity with Versatile Formulations and Applications"},{"label":"URL","value":"https://www.mdpi.com/2079-4991/15/4/290"},{"label":"Date","value":"Februrary 7, 2025"},{"label":"Justification (\"Paywalled\", \"OA\", \"Other (justify)\")","value":"OA"}]
|
Biology
|
Cancer Biology
|
Numerical Values
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Cancer-specific sialylation of insulin-like growth factor 1 receptor impairs therapeutic antibody binding and efficacy
|
https://www.biorxiv.org/content/10.1101/2025.10.17.682592v1
|
October 19, 2025
|
Researchers investigated how inhibiting sialylation affects the survival of ovarian cancer cells during ganitumab treatment in a clonogenic cell survival assay. Ovarian cancer cell line SKOV-3 was cultured in a humidified CO2 (5%) incubator at 37 °C in medium 199 and MCDB105 in a 1:1 ratio, supplemented with 5% fetal bovine serum (FBS), 1% penicillin and streptomycin (100 units/mL). For the clonogenic cell survival assay, they were pre-treated with 1 µg/ml ganitumab, 200 µM sialyltransferase inhibitor (STI; 3Fax-Peracetyl Neu5Ac), or 200 µM fucosyltransferase inhibitor (FTI; 2F-Peracetyl-Fucose) for 48 hours. Three hundred cells were then seeded in 6-well plates and cultured for 10 days under the following conditions: ganitumab alone, ganitumab + STI, or ganitumab + FTI. Colonies were fixed in methanol and stained with 1% crystal violet for visualization and counting. Colonies were normalized to the control.
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- Colony formation (number of colonies, expressed as % of control) in SKOV-3 ovarian cancer cell cultures in treatment groups: control, ganitumab only, ganitumab + STI (sialyltransferase inhibitor; 3Fax-Peracetyl Neu5Ac), ganitumab + FTI (fucosyltransferase inhibitor; 2F-Peracetyl-Fucose).
|
Researchers investigated how inhibiting sialylation affects the survival of ovarian cancer cells during ganitumab treatment in a clonogenic cell survival assay. Ovarian cancer cell line SKOV-3 was cultured in a humidified CO2 (5%) incubator at 37 °C in medium 199 and MCDB105 in a 1:1 ratio, supplemented with 5% fetal bovine serum (FBS), 1% penicillin and streptomycin (100 units/mL). For the clonogenic cell survival assay, they were pre-treated with 1 µg/ml ganitumab, 200 µM sialyltransferase inhibitor (STI; 3Fax-Peracetyl Neu5Ac), or 200 µM fucosyltransferase inhibitor (FTI; 2F-Peracetyl-Fucose) for 48 hours. Three hundred cells were then seeded in 6-well plates and cultured for 10 days under the following conditions: ganitumab alone, ganitumab + STI, or ganitumab + FTI. Colonies were fixed in methanol and stained with 1% crystal violet for visualization and counting. Colonies were normalized to the control.
Predict the number of expected colonies as % of control for the ganitumab + STI condition.
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#colGan+STI= [41.5 - 51.5] % derived from 46.5% at ganitumab + STI condition. Note: No CI/SE/SD reported > fallback ± 5 % applied.
|
- The insulin-like growth factor 1 receptor (IGF1R) is a key receptor tyrosine kinase involved in essential processes such as growth, survival, and metastasis in cancer that is targeted by an anti-IGF1R mAb (monoclonal antibody), ganitumab.
- Sialylation, the addition of sialic acid to terminal glycan chains, is a critical glycosylation modification on cell surface proteins that is upregulated in cancers.
|
[{"label":"RBK Item","value":"- The insulin-like growth factor 1 receptor (IGF1R) is a key receptor tyrosine kinase involved in essential processes such as growth, survival, and metastasis in cancer that is targeted by an anti-IGF1R mAb (monoclonal antibody), ganitumab.\n"},{"label":"Title","value":"Drugging IGF-1R in cancer: New insights and emerging opportunities"},{"label":"URL","value":"https://www.sciencedirect.com/science/article/pii/S2352304222000538"},{"label":"Date","value":"January 2023"},{"label":"Justification (\"Paywalled\", \"OA\", \"Other (justify)\")","value":"OA"},{"label":"RBK Item","value":"- Sialylation, the addition of sialic acid to terminal glycan chains, is a critical glycosylation modification on cell surface proteins that is upregulated in cancers.\n"},{"label":"Title","value":"Biological roles of glycans "},{"label":"URL","value":"https://academic.oup.com/glycob/article/27/1/3/2527575"},{"label":"Date","value":"January 1, 2017"},{"label":"Justification (\"Paywalled\", \"OA\", \"Other (justify)\")","value":"OA"}]
|
Biology
|
Ecology
|
Free-Format Question
|
Testing the reproducibility of ecological studies on insect behavior in a multi-laboratory setting identifies opportunities for improving experimental rigour
|
https://pmc.ncbi.nlm.nih.gov/articles/PMC12013911/
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April 22, 2025
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Researchers investigated ecological experiment reproducibility using a multi-laboratory approach. Three insect species: the turnip sawfly (A. rosae), the meadow grasshopper (P. parallelus), and the red flour beetle (T. castaneum) were used. P. parallelus were collected from the wild, T. castaneum was laboratory-grown, and A.rosae was a mix of wild and laboratory-grown insects (originated from the Bielefeld laboratory stock population, initially established from adults collected in the vicinity of Bielefeld, Germany and supplemented with wild-caught A. rosae adults). The effect of starvation on larval behaviour in A. rosae was investigated by measuring post-contact immobility (PCI) and activity following a simulated attack. Larvae were either starved or fed (non-starved). Stock population sawflies were housed in mesh cages (60 × 60 × 60 cm) within a laboratory environment at a 16:8-h light-to-dark cycle, approximately 60% relative humidity, and room temperature (15–25°C). Multiple male and female adults were introduced into a cage with mustard (Sinapis alba, Brassicaceae) plants for oviposition, giving rise to male and female offspring. After one week, the fed larvae of the newly hatched larvae were reared on non-flowering plants of cabbage (Brassica rapa var. pekinensis, Brassicaceae). Third- and fourth-instar larvae were collected from the cage, put individually in Petri dishes (5.5 cm diameter) lined with slightly moistened filter paper and provided with cabbage leaf discs, and were sent via mail to all three laboratories (70 larvae to each laboratory). Upon arrival, the larvae were transferred to fresh Petri dishes and were given ad libitum access to cabbage leaf discs obtained locally. Some larvae moulted during the experimental assay and were excluded from the experiment. The experiment was performed within 4 days after the arrival of the larvae. To measure PCI assay and activity, larvae were moved to clean Petri dishes with moist filter paper (1 larva per dish) and randomly allocated to a control or starvation treatment (N = 30 per treatment). In the starvation treatment, larvae had no access to cabbage leaves, while in the control treatment, larvae were provided cabbage leaves ad libitum and the position of the petri dish of the two treatments was alternated to avoid any spatial effects. After 3 h of treatment, the PCI duration of all larvae was measured. A clean Petri dish (5.5 cm in diameter) was placed over graph paper. To induce PCI, a larva was gently grasped at its midsection with soft-tip spring-steel forceps and dropped from a height of 5 cm onto the dish. PCI was recorded if the larva curled into a C-shape and remained motionless for at least one second. If PCI was not observed, the drop was repeated up to two additional times. The duration of PCI was determined from the onset of PCI until the larva straightened and moved at least 1 cm. Each larva was observed for up to 10 minutes. Following the PCI assay, all larvae were returned to their respective Petri dishes. One hour later (after 4 hours of starvation), larval activity was assessed. Individual larvae were transferred to clean, empty Petri dishes (5.5 cm diameter), and activity was recorded for 10 minutes using a video camera, with up to six dishes monitored simultaneously. Tracking software (software choice varied by laboratory) was used to extract the distance moved for each larva from the recorded videos.
|
- Post contact immobility or PCI duration (seconds) of fed and starved A. rosae larvae after exhibition of PCI.
- PCI activity levels (distance in cm) of fed and starved A. rosae larvae one hour after measuring PCI (= after 4 h of starvation treatment).
- Pearson's correlation between PCI duration and PCI activity levels of fed and starved A. rosae larvae.
|
Researchers investigated ecological experiment reproducibility using a multi-laboratory approach. Three insect species: the turnip sawfly (A. rosae), the meadow grasshopper (P. parallelus), and the red flour beetle (T. castaneum) were used. P. parallelus were collected from the wild, T. castaneum was laboratory-grown, and A.rosae was a mix of wild and laboratory-grown insects (originated from the Bielefeld laboratory stock population, initially established from adults collected in the vicinity of Bielefeld, Germany and supplemented with wild-caught A. rosae adults). The effect of starvation on larval behaviour in A. rosae was investigated by measuring post-contact immobility (PCI) and activity following a simulated attack. Larvae were either starved or fed (non-starved). Stock population sawflies were housed in mesh cages (60 × 60 × 60 cm) within a laboratory environment at a 16:8-h light-to-dark cycle, approximately 60% relative humidity, and room temperature (15–25°C). Multiple male and female adults were introduced into a cage with mustard (Sinapis alba, Brassicaceae) plants for oviposition, giving rise to male and female offspring. After one week, the fed larvae of the newly hatched larvae were reared on non-flowering plants of cabbage (Brassica rapa var. pekinensis, Brassicaceae). Third- and fourth-instar larvae were collected from the cage, put individually in Petri dishes (5.5 cm diameter) lined with slightly moistened filter paper and provided with cabbage leaf discs, and were sent via mail to all three laboratories (70 larvae to each laboratory). Upon arrival, the larvae were transferred to fresh Petri dishes and were given ad libitum access to cabbage leaf discs obtained locally. Some larvae moulted during the experimental assay and were excluded from the experiment. The experiment was performed within 4 days after the arrival of the larvae. To measure PCI assay and activity, larvae were moved to clean Petri dishes with moist filter paper (1 larva per dish) and randomly allocated to a control or starvation treatment (N = 30 per treatment). In the starvation treatment, larvae had no access to cabbage leaves, while in the control treatment, larvae were provided cabbage leaves ad libitum and the position of the petri dish of the two treatments was alternated to avoid any spatial effects. After 3 h of treatment, the PCI duration of all larvae was measured. A clean Petri dish (5.5 cm in diameter) was placed over graph paper. To induce PCI, a larva was gently grasped at its midsection with soft-tip spring-steel forceps and dropped from a height of 5 cm onto the dish. PCI was recorded if the larva curled into a C-shape and remained motionless for at least one second. If PCI was not observed, the drop was repeated up to two additional times. The duration of PCI was determined from the onset of PCI until the larva straightened and moved at least 1 cm. Each larva was observed for up to 10 minutes. Following the PCI assay, all larvae were returned to their respective Petri dishes. One hour later (after 4 hours of starvation), larval activity was assessed. Individual larvae were transferred to clean, empty Petri dishes (5.5 cm diameter), and activity was recorded for 10 minutes using a video camera, with up to six dishes monitored simultaneously. Tracking software (software choice varied by laboratory) was used to extract the distance moved for each larva from the recorded videos. If we compare results (three replicates) of each laboratory with regard to the effect of starvation on PCI duration, how many replicate(s) if any, would be reproducible amongst labs?
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When comparing the results for each of the laboratories, we found that the overall effect of starvation on PCI duration was reproduced in only two out of the three replicates
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- Reproducibility, i.e., the ability of a result to be replicated by an independent experiment in the same or different laboratory; also referred to as replicability, is a cornerstone of any scientific method.
- The larvae of A. rosae species feed on various Brassicaceae plants and can be an agricultural pest. In the larval stage, individuals can swiftly defoliate their host plants, consequently facing periods of starvation
- PCI is a behavioural response to physical interaction with a predator. During PCI, individuals remain motionless for a certain duration, a phenomenon that is also referred to as post-predation immobility, tonic immobility, thanatosis, or “death-feigning” behaviour.
|
[{"label":"RBK Item","value":"- Reproducibility, i.e., the ability of a result to be replicated by an independent experiment in the same or different laboratory; also referred to as replicability, is a cornerstone of any scientific method."},{"label":"Title","value":"Systematic heterogenization revisited: Increasing variation in animal experiments to improve reproducibility?"},{"label":"URL","value":"https://www.sciencedirect.com/science/article/abs/pii/S016502702300211X?via%3Dihub"},{"label":"Date","value":"January 1, 2024"},{"label":"Justification (\"Paywalled\", \"OA\", \"Other (justify)\")","value":"Paywalled"},{"label":"RBK Item","value":"- The larvae of A. rosae species feed on various Brassicaceae plants and can be an agricultural pest. In the larval stage, individuals can swiftly defoliate their host plants, consequently facing periods of starvation"},{"label":"Title","value":"An introduction to the natural history of British sawflies (Hymenoptera:Symphyta)."},{"label":"URL","value":"https://scispace.com/papers/an-introduction-to-the-natural-history-of-british-sawflies-2kyfv8g5zl"},{"label":"Date","value":"January 1, 1950"},{"label":"Justification (\"Paywalled\", \"OA\", \"Other (justify)\")","value":"OA"},{"label":"RBK Item","value":"- PCI is a behavioural response to physical interaction with a predator. During PCI, individuals remain motionless for a certain duration, a phenomenon that is also referred to as post-predation immobility, tonic immobility, thanatosis, or “death-feigning” behaviour."},{"label":"Title","value":"State dependency of behavioural traits is a function of the life stage in a holometabolous insect"},{"label":"URL","value":"https://www.sciencedirect.com/science/article/pii/S000334722300163X?via%3Dihub"},{"label":"Justification (\"Paywalled\", \"OA\", \"Other (justify)\")","value":"OA"}]
|
Chemistry
|
Organic Chemistry / Photochemistry
|
MCQ
|
Synthesis and characterization of blue light emitting star shaped π-conjugated oligomers based on dibenzothiophene-S,S-dioxide
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https://chemrxiv.org/engage/chemrxiv/article-details/68f622833e6156d3bef6aae8
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October 24, 2025
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Researchers synthesized a novel compound and characterized its absorbance and photoluminescence under different conditions.
To synthesize the novel compound, 0.042 g Pd(PPh3)2Cl2 (0.06 mmol, 0.015 eq), 6.63 g K2CO3, 2.001g 3,7-dibromo-1-iodobenzo[b,d]thiophene-S,S-dioxide (4.00 mmol, 1 eq), and 9.53 g (9,9-dioctyl-9H-fluorene-2yl)boronic acid (21.9 mmol, 5.5 eq) were added to a round bottom flask. After addition of 16 mL degassed water and 40 mL 1,4-dioxane, the charged flask was refluxed for 24 hours at 110 ºC under stirring in the dark. Subsequently, 0.014 g Pd(PPh3)2Cl2 (0.02 mmol, 0.02 eq) was added to the reaction at 95 ºC, and the reaction was further stirred for 8 hours at 110 ºC (32 hours total). Evaporation of the resulting mixture was performed until ~20 mL of 1,4-dioxane and water remained. Quenching proceeded with 100 mL water, extraction was performed into 3 x 100 mL DCM, and evaporation to dryness and freeze drying followed. Flash column chromatography was performed using Biotage disposable PTFE columns, filled with silica gel LC60 (40–60 μM) (Telydyne Isco automatic flash chromatograph, Combiflash Rf 200 ) to obtain pure novel compound (95%).
The absorption and photoluminescence spectra of the novel compound were recorded in solution in different HPLC grade solvents (CHCl3, DCM, benzonitrile, hexane, EtOH and THF in 10 mm path length quartz cells) and in solid state using the (Shimadzu UV-3600 UV–vis-NIR spectrophotometer and Horiba Yvon Fluromax-4) at room temperature. Solid state measurements were performed for spin-coated films deposited on 12.5 mm circular quartz substrates, prepared by spin coating from oligomer solutions (1–3 mg per 1 mL of DCM) at 3000-4000 rpm. The solutions were deoxygenated by bubbling with argon for about 10 minutes before the measurements.
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- Absorption spectra (250 - 500 nm) of the novel compound in different solvents (CHCl3, DCM, benzonitrile, hexane, EtOH and THF) and in thin film (Shimadzu UV-3600 UV–vis-NIR spectrophotometer).
- Photoluminescence spectra (350 - 700 nm) of the novel compound in different solvents (CHCl3, DCM, benzonitrile, hexane, EtOH and THF) (Horiba Yvon Fluromax-4).
|
Researchers synthesized a novel compound by adding 0.042 g Pd(PPh3)2Cl2 (0.06 mmol, 0.015 eq), 6.63 g K2CO3, 2.001g 3,7-dibromo-1-iodobenzo[b,d]thiophene-S,S-dioxide (4.00 mmol, 1 eq), 9.53 g (9,9-dioctyl-9H-fluorene-2yl)boronic acid (21.9 mmol, 5.5 eq), 16 mL degassed water and 40 mL 1,4-dioxane to a round bottom flask and refluxing for 24 hours at 110 ºC under stirring in the dark. 0.014 g Pd(PPh3)2Cl2 (0.02 mmol, 0.02 eq) was added at 95 ºC and the reaction continued for 8 hours at 110 ºC (32 hours total). The resulting mixture was evaporated until ~20 mL of 1,4-dioxane and water remained, quenched with 100 mL of water, extracted with 3 x 100 mL DCM, dry-evaporated and freeze dried. The novel compound was purified by flash column chromatography (silica gel LC60 (40–60 μM)) to obtain pure novel compound (95%). The absorption and photoluminescence spectra of the novel compound were recorded in solution in different solvents (CHCl3, DCM, benzonitrile, hexane, EtOH and THF in 10 mm path length quartz cells) and in spin-coated films (1–3 mg per 1 mL of DCM) deposited on 12.5 mm circular quartz substrates. Which of the following outcomes is most likely? (Mark all correct options).
A. The absorption spectra of the novel compound in hexane showed a slight blue shift while benzonitrile showed no shift.
B. The absorption spectra of the novel compound in CHCl3, THF, DCM and EtOH were overlapped with no significant observable shifts.
C. The absorption spectra of the novel compound showed four peaks in thin film, with the highest intensity peak observed in thin film being red-shifted, when compared to the absorption in benzonitrile.
D. The photoluminiscence spectra showed an overlap between CHCl3, DCM and benzonitrile while hexane showed a clear blue (hypsochromic) shift and EtOH and THF showed slight red (bathochromic) shifts.
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B. The absorption spectra of the novel compound in CHCl3, THF, DCM and EtOH were overlapped with no significant observable shifts.
C. The absorption spectra of the novel compound showed four peaks in thin film, with the highest intensity peak observed in thin film being red-shifted, when compared to the absorption in benzonitrile.
D. The photoluminiscence spectra showed an overlap between CHCl3, DCM and benzonitrile while hexane showed a clear blue (hypsochromic) shift and EtOH and THF showed slight red (bathochromic) shifts.
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- Dibenzothiophene-S,S-dioxides are stable molecules with modifiable properties, which have been used in organic light emitting diodes (OLEDs) due to their enhanced quantum efficiencies and photoluminescence (PL) in both solid and solution states.
- The dibenzothoiphene-S,S-dioxide molecule contains an electrophilic SO2 group that decreases the lowest unoccupied molecular orbital (LUMO) energy of the molecule and aids in electron transfer between the donor and acceptor moieties.
- More polar solvents facilitate dibenzothiophene-S,S-dioxide and fluorene to show a bathochromic (red) shift while a hypsochromic (blue) shift is shown in less polar solvents.
|
[{"label":"RBK Item","value":"- Dibenzothiophene-S,S-dioxides are stable molecules with modifiable properties, which have been used in organic light emitting diodes (OLEDs) due to their enhanced quantum efficiencies and photoluminescence (PL) in both solid and solution states.\n"},{"label":"Title","value":" Stabilization of Semiconducting Polymers with Silsesquioxane"},{"label":"URL","value":"https://advanced.onlinelibrary.wiley.com/doi/abs/10.1002/adfm.200390000"},{"label":"Date","value":"January 30, 2003"},{"label":"Justification (\"Paywalled\", \"OA\", \"Other (justify)\")","value":"Paywalled version is the one cited by the paper"},{"label":"RBK Item","value":"- The dibenzothoiphene-S,S-dioxide molecule contains an electrophilic SO2 group that decreases the lowest unoccupied molecular orbital (LUMO) energy of the molecule and aids in electron transfer between the donor and acceptor moieties.\n"},{"label":"Title","value":"Intramolecular Charge Transfer Assisted by Conformational Changes in the Excited State of Fluorene-dibenzothiophene-S,S-dioxide Co-oligomers"},{"label":"URL","value":"https://pubs.acs.org/doi/10.1021/jp0643653"},{"label":"Date","value":"September 2, 2006"},{"label":"Justification (\"Paywalled\", \"OA\", \"Other (justify)\")","value":"Paywalled version is the one cited by the paper"},{"label":"RBK Item","value":"- More polar solvents facilitate dibenzothiophene-S,S-dioxide and fluorene to show a bathochromic (red) shift while a hypsochromic (blue) shift is shown in less polar solvents."},{"label":"Title","value":"Intramolecular Charge Transfer Assisted by Conformational Changes in the Excited State of Fluorene-dibenzothiophene-S,S-dioxide Co-oligomers"},{"label":"URL","value":"https://pubs.acs.org/doi/10.1021/jp0643653"},{"label":"Date","value":"September 2, 2006"},{"label":"Justification (\"Paywalled\", \"OA\", \"Other (justify)\")","value":"Paywalled version is the one cited by the paper"}]
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Chemistry
|
Biochemistry
|
MCQ
|
Cobalt(III) Schiff Base Complexes as Irreversible Inhibitors of the Metallo-β-Lactamase NDM-1
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https://chemrxiv.org/engage/chemrxiv/article-details/68534e29c1cb1ecda0c0449d
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June 21, 2025
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Researchers tested a library of cobalt(III) Schiff base complexes (Co(III)-sb) for irreversible inhibition of the metallo-β-lactamase known as NDM-1. The complexes were synthesized via equimolar chelation of CoCl₂·6H₂O with equatorial ligands (acacen, tfacen, phacen derivatives) under inert atmosphere, followed by addition of excess axial ligands (ammonia, 2-methylimidazole, benzylamine) and oxidation to Co(III) using molecular O₂. Inhibition potency was determined using the nitrocefin assay, a colorimetric method that quantifies β-lactamase activity via continuous absorbance monitoring at 490 nm. NDM-1 samples were incubated with varying concentrations of Co(III)-sb complexes, and time-dependent IC₅₀ values were determined by monitoring nitrocefin turnover at 5-minute intervals over 3 hours at room temperature.
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- IC₅₀ values for NDM-1 inhibition by different Co(III)-sb complexes
- Inactivation rate constants (kᵢₙₐcₜ)
- Inactivation constants (Kᵢ) for irreversible inhibition
- Inactivation efficiency (kᵢₙₐcₜ/Kᵢ)
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Researchers evaluated a library of cobalt(III) Schiff base complexes, featuring different equatorial ligands such as acacen, tfacen, and phacen derivatives, and axial ligands including ammonia, 2-methylimidazole, and benzylamine, for irreversible inhibition of metallo-β-lactamase (NDM-1). The complexes were tested using time-dependent IC₅₀ determinations. Which of the following best explains the observed variation in potency and time-dependent inhibition efficiency among the different cobalt(III) Schiff base complexes (Co(III)-sb), with particular focus on the role of axial ligands and their interaction with the NDM-1 active site?
a) Complexes with benzylamine as the axial ligand show higher potency due to its stronger donor properties, leading to faster ligand exchange and more effective Zn(II) displacement.
b) Complexes with ammonia as the axial ligand exhibit the strongest inhibition because its weak donor property facilitates slower exchange, allowing for prolonged interaction with NDM-1.
c) Complexes with 2-methylimidazole exhibit the highest potency although its weaker donor strength may result in a lower exchange rate that most efficiently displaces Zn(II) from the active site.
d) Complexes with 2-methylimidazole show reduced potency compared to benzylamine complexes because 2-methylimidazole has a stronger donor property, leading to excessive exchange and weakening of the cobalt-enzymatic interaction.
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c) Complexes with 2-methylimidazole exhibit the highest potency although its weaker donor strength may result in a lower exchange rate that most efficiently displaces Zn(II) from the active site.
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- Metallo-β-lactamases (MBLs): Zinc-dependent bacterial enzymes that hydrolyze β-lactam antibiotics and contribute to antibiotic resistance
- Cobalt(III) Schiff base complexes: Octahedral coordination compounds with tetradentate equatorial ligands and monodentate axial ligands that can undergo ligand exchange
- Nitrocefin assay: Colorimetric method that monitors β-lactamase activity through hydrolysis-induced color change
- Inactivation efficiency (kᵢₙₐcₜ/Kᵢ): The primary kinetic parameter for evaluating irreversible inhibitors, with higher values indicating greater potency
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[{"label":"RBK Item","value":"Metallo-β-lactamases (MBLs): Zinc-dependent bacterial enzymes that hydrolyze β-lactam antibiotics and contribute to antibiotic resistance"},{"label":"RBK Item","value":"Molecular mechanisms of antibiotic resistance"},{"label":"URL","value":"https://www.nature.com/articles/nrmicro3380"},{"label":"Date","value":"December 1, 2014"},{"label":"Justification (\"Paywalled\", \"OA\", \"Other (justify)\")","value":"Paywalled but directly referenced by the article. "},{"label":"RBK Item","value":"Cobalt(III) Schiff base complexes: Octahedral coordination compounds with tetradentate equatorial ligands and monodentate axial ligands that can undergo ligand exchange"},{"label":"Title","value":"Tuning Cobalt(III) Schiff Base Complexes as Activated Protein Inhibitors"},{"label":"URL","value":"https://pubs.acs.org/doi/10.1021/acs.inorgchem.5b01415"},{"label":"Date","value":"September 2, 2015"},{"label":"Justification (\"Paywalled\", \"OA\", \"Other (justify)\")","value":"Paywalled but directly referenced by the article. "}]
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Chemistry
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Wood chemistry, nano-synthesis
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MCQ
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Additive Manufacturing of Lignocellulosic Aerogels from Minimally Processed Waste Streams
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https://onlinelibrary.wiley.com/doi/full/10.1002/smll.202412509
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August 8, 2025
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Researchers prepared three lignocellulose paste samples (LCPs)- LCP-C (crude), LCP-B (blonde), LCP-W (white) representing varying degrees of bleaching were prepared from Birch chip slurry made using the Sunburst process and imaged them with AFM. Lignocellulose particles (LCP-W, LCP-C, LCP-B) at pH > 9.5 were diluted with Milli-Q water to solid contents at 0.01 wt% and centrifuged at 1000rpm for 15 minutes. The supernatants were cast on cleaned silicon wafers precoated with cationic adhesive layer before dying into films. Dried lignocellulosic paste films were imaged in air in tapping mode on Cypher VRS (Oxford Instruments) with silicon cantilever with the following parameters: AC200 TS, f = 100.4 - 169.43 kHz, F = 2.88 -12.79 N/m.
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-AFM height and phase images of each lignocellulosic paste in tapping mode.
-AFM nanoparticle length measurement extracted from each lignocellulosic paste sample.
-Gravimetric nano-yield measurement extracted from each centrifuged lignocellulosic paste sample.
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Researchers prepared three lignocellulose paste samples (LCPs)- LCP-C (crude), LCP-B (blonde), LCP-W (white) using the Sunburst process. Films were cast onto silicon wafers for imaging with AFM. Based on AFM/nano-yield measurements, which of the samples contain less than 8wt% of ~100nm particles?
A) LCP-W only
B) LCP-B only
C) LCP-B and LCP-W
D) LCP-C and LCP-B
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C) LCP-B and LCP-W
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-The Sunburst process is a pretreatment method for breaking down lignocellulosic biomass using heat, pressure, and acidity to deconstruct it into a slurry of its components: lignin, cellulose, and hemicellulose.
-Increased bleaching of of the LCP after Sunburst process results in enrichment of cellulose by loss of lignin and hemicellulose.
-Nanoparticles formed during bleaching of LCPs are usually composed of lignin.
|
[{"label":"Title","value":"Methods of making specialized cellulose and other products from biomass"},{"label":"URL","value":"https://patents.google.com/patent/US20210285155A1/en"},{"label":"Date","value":"September 16, 2021"},{"label":"Justification (\"Paywalled\", \"OA\", \"Other (justify)\")","value":"OA"},{"label":"RBK Item","value":"-The Sunburst process is a pretreatment method for breaking down lignocellulosic biomass using heat, pressure, and acidity to deconstruct it into a slurry of its components, lignin, cellulose, and hemicellulose."}]
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Chemistry
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Inorganic synthesis, Catalysis
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Free-Format Question
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Synthesis of Sulfated Sn–Zr Mesoporous Catalysts for the Selective Dehydration of Hexose-Type Monosaccharides
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https://chemistry-europe.onlinelibrary.wiley.com/doi/10.1002/open.202400480
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July 13, 2025
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Researchers explored catalytic activity of sulfated and Zr/Sn impregnated mesoporous materials for the conversion of fructose to HMF. SBA-15 mesoporous silica support was synthesized by the sol-gel method. P123 structure-directing agent was dissolved in H2O/HCl solution at 50C before adding the TEOS (Tetraethyl orthosilicate) under vigorous stirring over 5 minutes. The molar ratios of precursors was 1 TEOS: 158 H2O: 6 HCl: 0.016 P123. The mixture was then allowed to stand for 20 hours and subjected to a hydrothermal treatment at 80C for 48 hours. After cooling, the solids were filtered, washed and dried overnight. The template was removed by a two-step calcination, at 500C for 5 hours under both nitrogen and oxygen atmospheres at 20sccm flow rate.
The material was then functionalized via wet impregnation. Zr was incorporated with zirconium oxychloride solution to form Zr–SBA-15 with Si/Zr molar ratios of 10, 20, and 30. The sample was dried overnight at 60C before calcination in oxygen at 500C for 5 hours. The materials were further modified by sulfation, which required stirring the material in a 10 vol% sulfuric acid solution for 12 hours, followed by drying at 100C for 3 hours, and then calcination in air at 500C for 5 hours. By alternating these steps, including the coimpregnation of Sn as Sn(CH3)2Cl2 at 2, 5, and 8 wt% (following the same thermal processing as Zr-SBA-15) the following samples were produced: Sn–Zr–SBA-15, SO4/Zr–SBA-15, Sn–SO4/Zr–SBA-15, and SO4/Sn–Zr–SBA-15. Based on the order of the functionalization steps, either Zr or both Sn and Zr were sulfated.
Researchers evaluated the catalytic performance of various synthesized SBA-15 catalysts for the selective dehydration of fructose to HMF (5-hydroxymethylfurfural). The catalyst tests were conducted in a stirred glass tube reactor, using 1.5 mL of a 30 wt% aqueous fructose solution and 3.5 mL of an organic phase (MIBK/2-butanol) as an extracting agent, along with 50 mg of catalyst. To identify optimal conditions for maximizing HMF yield, key parameters were varied, including temperatures (120 to 150C), reaction times (20 to 150 min), and catalyst loadings (25 to 75 mg). Additionally, the influence of varying Zr/Sn ratios (0.98, 1.98, 3.96, and 9.89) in the SO4/Sn–Zr–SBA-15 material on fructose conversion and HMF selectivity was investigated. Cyclic performance was investigated over 4 catalytic cycles (with filtration/washing/drying) where the catalyst was regenerated by calcination (500C for 5 hours) before cycle 4. Reaction products were primarily analyzed and quantified using HPLC (High Pressure Liquid Chromatography) with both refractive index (RI) and UV–visible detectors, employing an Aminex HPX-87H column and a 5 mM H2SO4 mobile phase, while selected organic phase products were analyzed by GC (Gas Chromatography) coupled with an FID (Flame Ionization Detector). Elemental analysis (EA) and inductively coupled plasma-optical emission spectrometry (ICP-OES) were used to determine Sn, Zr, S, C, N, and H content.
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-Fructose conversion (%) and HMF yield (%) for SBA-15, Zr-SBA-15, Sn–Zr–SBA-15, SO4/Zr–SBA-15, Sn–SO4/Zr–SBA-15, and SO4/Sn–Zr–SBA-15 at 150C for 120 minutes as measured by HPLC
-Fructose conversion (%) and HMF selectivity (%) of SO4/Sn–Zr–SBA-15 at varying Zr/Sn ratios (0.98, 1.98, 3.96, and 9.89) at 150C for 120 minutes by HPLC
-Fructose conversion (%) and HMF selectivity (%) of SO4/Sn–Zr–SBA-15 at 150C for 120 minutes over 4 catalytic cycles, with regeneration at 500C for 5 hours before cycle 4 as measured by HPLC
-EA and ICPOES for determination of Sn, Zr, S, C, N, and H content before cycling and after regeneration
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Researchers explored catalytic activity of sulfated and Zr/Sn impregnated SBA-15 for the conversion of fructose to HMF. Catalyst supports were made by the sol gel method, followed by wet impregnation and calcination with Zr and Sn, and sulfation in sulfuric acid (and calcination) to produce SBA-15, Zr-SBA-15, Sn–Zr–SBA-15, SO4/Zr–SBA-15, Sn–SO4/Zr–SBA-15, and SO4/Sn–Zr–SBA-15 depending on the order of impregnation and sulfation steps. Fructose conversion (%) and HMF yield (%) for SBA-15, Zr-SBA-15, Sn–Zr–SBA-15, SO4/Zr–SBA-15, Sn–SO4/Zr–SBA-15, and SO4/Sn–Zr–SBA-15 at 150C for 120 minutes were measured by HPLC. Fructose conversion (%) and HMF selectivity (%) of SO4/Sn–Zr–SBA-15 at varying Zr/Sn ratios (0.98, 1.98, 3.96, and 9.89) at temperatures between 100C and 400C were also measured. Cyclic catalytic stability of of SO4/Sn–Zr–SBA-15 was explored at 150C for 120 minutes over 4 catalytic cycles, with regeneration at 500C for 5 hours before cycle 4. EA and ICPOES for determination of Sn, Zr, S, C, N, and H content before cycling and after regeneration. How are the fructose conversion (%) and HMF selectivity (%) expected to change with Zr/Sn ratio as seen by ICPOES?
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Fructose conversion (%) increases monotonically with Zr/Sn ratio, while HMF selectivity increases between 0.98 and 3.96, but then decreases with greater Zr content.
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-SBA-15 mesoporous catalysts provide high applicability in catalysis due to its thick pore walls, which enhance thermomechanical stability.
-Homogenously dispersed acid sites on a mesoporous template can assist in sugar conversion by reducing the carbonaceous species production.
-Sulfated SnO2 and ZrO2 are known to produce strong acidic surface sites on siliceous materials
|
[{"label":"RBK Item","value":"SBA-15 mesoporous catalysts provide high applicability in catalysis due to its thick pore walls, which enhance thermomechanical stability."},{"label":"Title","value":"Sn-modified SBA-15 with tailored acid properties for efficient 5-hydroxymethylfurfural production from glucose."},{"label":"URL","value":"https://doi.org/10.1016/j.biombioe.2024.107202"},{"label":"Date","value":"May, 2024"},{"label":"Justification (\"Paywalled\", \"OA\", \"Other (justify)\")","value":"Paywalled"},{"label":"RBK Item","value":"Sulfated SnO2 and ZrO2 are known to produce strong acidic surface sites on siliceous materials"},{"label":"Title","value":"Esterification of Succinic Acid Using Sulfated Zirconia Supported on SBA-15"},{"label":"URL","value":"https://onlinelibrary.wiley.com/doi/abs/10.1002/ceat.202000333"},{"label":"Date","value":"April 12, 2021"},{"label":"Justification (\"Paywalled\", \"OA\", \"Other (justify)\")","value":"Paywalled"}]
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Chemistry
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Materials Chemistry / Catalysis
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MCQ
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Homogeneous Boroaluminate Xerogels: Synthesis, Characterization, and Catalysis
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https://chemrxiv.org/engage/chemrxiv/article-details/685115a23ba0887c33fb6937
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May 12, 2025
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Researchers synthesized and evaluated boroaluminate xerogels as catalysts for the ethanol dehydration reaction. For this purpose, two types of xerogels were manufactured following different procedures.
For the first xerogel type, in a dry box, 2 g of AlCl3 (15 mmol) were dissolved in warm toluene (30.0 cm^3) within a Schlenk flask. Once equilibrated to room temperature, 1.67 cm^3 trimethyl borate (15.0 mmol) were added dropwise into the solution, which was subsequently heated to 115 °C and refluxed for 2 h under an inert atmosphere. The reaction was subsequently kept at 105 °C for 72 h. After volatiles evaporation, the gel was subject to high vacuum for 48 h at 60 ºC. Once equilibrated to room temperature, the xerogel was transferred into a calcination vessel within the glovebox, and calcined in an ambient air atmosphere at 600 °C (3 °C min–1; 180 min isotherm). The reaction was product was named AlOB-1.
For the second xerogel type, in a dry box, 2 g of AlCl3 (15 mmol) were dissolved in warm toluene (30.0 cm^3) within a Schlenk flask. Pluronic F127 (20 wt%) and, subsequently, 1.25 cm^3 trimethyl borate (11.3 mmol), were added to the solution. The reaction vessel was subsequently heated to 115 ºC and refluxed for 2 h under an inert atmosphere. The reaction was subsequently kept at 105 °C for 72 h. After volatiles evaporation, the gel was subject to high vacuum for 48 h at 60 ºC. Once equilibrated to room temperature, the xerogel was transferred into a calcination vessel within the glovebox, and calcined in an ambient air atmosphere at 600 °C (3 °C min–1; 180 min isotherm). The reaction was product was named AlOB-2.
For testing samples in the catalytic reaction of ethanol dehydration, the calcined samples (200 mg) with grain sizes 0.2 - 0.4 mm selected by sieving, were mixed and adjusted to an equal total volume with glass beads (0.5–1 mm). Ethanol (with 5 mol% of pentane as an internal standard) was fed at a rate of 4.771 mmol / h of ethanol (WHSV = 1.1 g (EtOH) / g (cat) / h) in nitrogen carrier gas (50 ml/min). A fix-bed catalytic reactor was employed for the catalytic tests, which was connected to an HP 6890 Gas Chromatograph (6 injections at 205, 240, and 275 °C) equipped with a flame ionization detector (FID) and a Thermo Scientific TG-BOND U column (30 m long, internal diameter of 0.32 mm, film thickness of 10 μm). The tests were carried out at atmospheric pressure.
Specific surface area and porosity were measured for samples before/after the ethanol catalysis reaction by nitrogen adsorption, using an Autosorb iQ3 (Quantachrome Instrument) porosimeter. Adsorption and desorption isotherms were measured at -195.7 ºC. The specific surface area (m^2/g) was determined by Brunauer-Emmett-Teller (BET) analysis using isotherms measured in the 0.05–0.30 relative pressure range. Average pore sizes (nm) were determined using the Barret-Joyner-Halenda (BJH) method.
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- Specific surface area (m^2/g) of AlOB-1 and AlOB-2 catalysts before and after catalytic reaction of ethanol dehydration (Brunauer-Emmett-Teller (BET) analysis)
- Average pore size (nm) of AlOB-1 and AlOB-2 catalysts before and after catalytic reaction of ethanol dehydration (Barret-Joyner-Halenda (BJH) method)
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Two different porous metal oxide catalysts were obtained from a non-hydrolytic sol-gel process. AlOB-1 was obtained using AlCl3 (2.00 g, 15.0 mmol) and 1.67 cm^3 trimethyl borate (15.0 mmol) as precursors, and warm toluene (30.0 cm^3 ) as solvent, with calcination at 600 ºC for 180 minutes. AlOB-2 was obtained using AlCl3 (2.00 g, 15.0 mmol) and trimethyl borate (1.25 cm^3 , 11.3 mmol) as precursors, warm toluene (30.0 cm^3 ) as solvent, and F127 (20 wt%) as template, with calcination at 600 ºC for 180 minutes. For testing the calcined samples (0.2 - 0.4 mm grain sizes) in the catalytic reaction of ethanol dehydration, a fix-bed catalytic reactor was employed, connected to an HP 6890 Gas Chromatograph (6 injections at 205, 240, and 275 °C). Samples (200 mg) were mixed and adjusted to an equal total volume with glass beads (0.5–1 mm) and ethanol (with 5 mol% of pentane as an internal standard) was fed at a rate of 4.771 mmol / h of ethanol (WHSV = 1.1 g (EtOH) / g (cat) / h) in nitrogen carrier gas (50 ml/min); taking place the reactions at atmospheric pressure. The specific surface area (m^2/g) and average pore size (nm) of the catalysts were measured by nitrogen adsorption, before and after the ethanol catalysis reaction, following Brunauer-Emmett-Teller (BET) analysis (0.05–0.30 relative pressure range isotherms) and the Barret-Joyner-Halenda (BJH) method.
Which of the following outcomes is most likely?
A) After catalysis, the surface area of AlOB-1 increased while the pore size of AlOB-2 remained constant.
B) Before catalysis, the surface area of AlOB-1 was higher than the surface area of AlOB-2, while the pore size was similar.
C) After catalysis, the surface area of AlOB-1 did not increase while the pore size of AlOB-2 increased.
D) Before catalysis, the surface area of AlOB-2 was higher than the surface area of AlOB-1, while the pore size was higher in AlOB-1.
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C) After catalysis, the surface area of AlOB-1 did not increase while the pore size of AlOB-2 increased.
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- Porous metal oxides are a class of materials which versatile composition, structure, and physicochemical properties enable their application as catalysts.
- Boria-alumina mixed oxides are amorphous mesoporous materials with specific surface areas 200–300 m^2/g.
- The non-hydrolytic sol-gel method is a technique employed to prepare materials of similar nature than boroaluminate xerogels.
|
[{"label":"RBK Item","value":"- Porous metal oxides are a class of materials which versatile composition, structure, and physicochemical properties enable their application as catalysts."},{"label":"Title","value":"Recent developments of metal oxide based heterostructures for photocatalytic applications towards environmental remediation"},{"label":"URL","value":"https://www.sciencedirect.com/science/article/abs/pii/S002245961830327X?via%3Dihub"},{"label":"Date","value":"August 9, 2018"},{"label":"Justification (\"Paywalled\", \"OA\", \"Other (justify)\")","value":"Paywalled version is the one cited for the given RBK item in the paper"},{"label":"RBK Item","value":"- Boria-alumina mixed oxides are amorphous mesoporous materials with specific surface areas 200–300 m^2/g."},{"label":"Title","value":"Characterization of microporous amorphous alumina–boria"},{"label":"URL","value":"https://pubs.rsc.org/en/content/articlelanding/1992/ft/ft9928802065"},{"label":"Date","value":"1992"},{"label":"Justification (\"Paywalled\", \"OA\", \"Other (justify)\")","value":"Paywalled version is the one cited for the given RBK item in the paper"},{"label":"RBK Item","value":"- The non-hydrolytic sol-gel method is a technique employed to prepare materials of similar nature than boroaluminate xerogels.\n"},{"label":"Title","value":"Synthesis of aluminophosphate xerogels by non-hydrolytic sol–gel condensation of EtAlCl2 with trialkylphosphates"},{"label":"URL","value":"https://link.springer.com/article/10.1007/s10971-019-04953-0"},{"label":"Date","value":"March 15, 2019"},{"label":"Justification (\"Paywalled\", \"OA\", \"Other (justify)\")","value":"Paywalled version is the one cited for the given RBK item in the paper"}]
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Chemistry
|
Combustion Chemistry
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Free-Format Question
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Experimental and Numerical Investigations of Soot Formation in the Laminar to Turbulent Transition of an Acetylene Diffusion Flame
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https://pubs.acs.org/doi/10.1021/acsomega.5c05165
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October 8, 2025
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Acetylene was emitted from a stainless-steel tube, and its flow was controlled by a mass flow controller in order to produce an acetylene diffusion flame. The tubes used for combustion had internal diameters (Din) of 0.5, 0.6, and 0.7 mm respectively, with wall thicknesses of 0.15 mm and lengths of 200 mm maintained to allow full internal development. The vertical height between the tube and the adjustable base (h) was measured with a ruler and adjusted manually. Temperature (T) was measured through a two-color pyrometer (ONYX-S2C) with a range from 700 to 3000 °C at a measurement point 5 cm above the tube and sampling rate of 1000 Hz. Oven-dried glass fiber filters collected the soot, collection time being 1 min for most cases, with increase up to 5 min alongside an increase in turbulence to ensure at least 15 mg of soot was captured. An electronic balance with an accuracy of 0.1 mg was employed for weighing, and each measurement was repeated three times and averaged. A 150 mm diameter filter paper was used only once. An initial flow rate of 290 L/min was achieved via centrifugal ventilator. Flame images were recorded as well.
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• Soot formation rate (ṁsoot) i.e., mass collected on oven-dried glass-fiber filters and reported as mass/collection time (each reading repeated thrice and averaged).
• Inlet Reynolds number (Re) was computed from acetylene flow density, average velocity, dynamic viscosity, and tube internal diameter (Din)
• Flame shape, height, width, and fluctuations recorded by imaging.
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An acetylene diffusion flame is emitted from a stainless-steel nozzle (internal diameter, Din = 0.6 mm) by researchers to investigate the effects of Reynolds number (Re) on soot formation and flame behavior. The inlet Re is increased (2412, 2733, 2974, 3216, 3859) so the flow transitions from laminar to transitional to turbulent, and the soot formation rate (ṁsoot) is measured for every case. Based on these conditions, how is the soot formation rate (ṁsoot) expected to vary and how is the flame behavior changes across the three states (laminar, transitional, turbulent).
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In the laminar state, the flame remained slender and stable, and ṁsoot increased linearly with Re at a growth rate positively correlated with Din. Upon entering the transitional state, the flame exhibited intermittent fluctuations, and ṁsoot reached its peak. With the further increase in Re, the flame exhibited significant width expansion and slight height reduction. Due to the increases in k (turbulent kinetic energy), and Dt (turbulent diffusion coefficients), ṁsoot decreased exponentially by over 95%.
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• Increasing the volume flow rate of the accompanying air increase the volume fraction of soot, and increasing the fuel volume flow rate would first increase and then decrease the volume fraction of soot.
• Flames interact with turbulence when they transition from laminar to turbulent states.
• The flame transition from laminar to turbulent is mainly caused by an incipient turbulent flow near the flame base for a lifted flame. In fact, the precise prediction of the transition region is still difficult.
• A lifted flame can appear with an increase in the flow rate. It is stabilized based on the competition between flame propagation speed and local flow velocity near the flame edge.
|
[{"label":"RBK Item","value":"Increasing the volume flow rate of the accompanying air increase the volume fraction of soot, and increasing the fuel volume flow rate would first increase and then decrease the volume fraction of soot."},{"label":"Title","value":"Numerical Simulation of Soot Formation in Ethylene Laminar Diffusion Flame"},{"label":"URL","value":"https://www.mdpi.com/2571-6255/6/8/316"},{"label":"Date","value":"August 14, 2023"},{"label":"Justification (\"Paywalled\", \"OA\", \"Other (justify)\")","value":"OA"},{"label":"RBK Item","value":"Flames interact with turbulence when they transition from laminar to turbulent states."},{"label":"Title","value":"A semi-empirical laminar-to-turbulent flame transition model coupled with G equation for early flame kernel development and combustion in spark-ignition engines"},{"label":"URL","value":"https://doi.org/10.1177/1468087419864748"},{"label":"Date","value":"July 19, 2019"},{"label":"Justification (\"Paywalled\", \"OA\", \"Other (justify)\")","value":"Paywalled"},{"label":"RBK Item","value":"The flame transition from laminar to turbulent is mainly caused by an incipient turbulent flow near the flame base of a lifted flame making the precise prediction of the transition region difficult."},{"label":"Title","value":"On the transition modes and mechanisms for laminar to turbulent lifted jet diffusion flames at normal- and micro-gravity"},{"label":"URL","value":"https://doi.org/10.1016/j.combustflame.2023.113269"},{"label":"Date","value":"February, 2024"},{"label":"Justification (\"Paywalled\", \"OA\", \"Other (justify)\")","value":"Paywalled"},{"label":"RBK Item","value":"Lifted flames can appear as flow rate increases, being stabilized based on the interplay of flame propagation speed and local flow velocity near the edge of the flame."},{"label":"Title","value":"Blowout of non-premixed turbulent jet flames with coflow under microgravity condition"},{"label":"URL","value":"https://doi.org/10.1016/j.combustflame.2019.08.041"},{"label":"Date","value":"December, 2019"},{"label":"Justification (\"Paywalled\", \"OA\", \"Other (justify)\")","value":"Paywalled"}]
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Chemistry
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Natural Products / Analytical Chemistry
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Free-Format Question
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Studies on the Use of Loan Extraction to Produce Natural Shower Gels (Cosmetic) Based on Grape Pomace Extracts—The Effect of the Type of Surfactant Borrowed
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https://www.mdpi.com/1420-3049/30/18/3709
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September 12, 2025
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Researchers investigated the effects of different extraction solutions in the extraction process of natural compounds from grape pomace.
The pomace from a mixture of Solaris, Muscat and Riesling white grapes was obtained from the Cwielong-Olszewski vineyard (established in 2013 in Balcarzowice, Opole Province, Poland). All grapes were harvested at full ripeness (early September 2024). All grape varieties exhibited a spheroidal shape with a diameter of ~16 mm, with loose clusters, and average cluster weight 150 - 200 g. The grape pomace was de-stemmed, pressed in a fruit and wine press, and delivered to the laboratory three days after harvesting and pressing; being then frozen at −18 ºC until analysis.
Before extraction, the pomace was thaw for 2 h at 22 ºC. Aqueous solutions (2% w/w) of decyl glucoside (DG), cocamidopropyl betaine (CB), sodium coco-sulfate (SCS), and disodium cocoyl glutamate (DSCG) were used as the different extraction media tested. A mixture of benzyl alcohol, benzoic acid, dehydroacetic acid, and tocopherol (0.5% w/w) was used as preservative for all solutions. The grape pomace (400 g) was ground with a laboratory knife mill (Cutter Mixer R5 Plus, Robot Coupe, Vincennes, France), mixed with 100 g of the extraction solutions, and stirred at 380 rpm for 20 min at room temperature. The resulting extract was filtered under vacuum using a bottle-top sterile filter units (0.45 μm pore size; polyethersulfone membrane) and the filtrate was used for further studies. The filtrates generated with the different extraction solutions were designated according to the composition of the extraction solution (i.e. DG: GPE_DG; CB: GPE_CB; SCS: GPE_SCS; DSCG: GPE_DSCG).
The total phenolic content (TPC) of the different extracts was measured using the Folin–Ciocalteu (FC) method, with slight modifications. Extracts were diluted 1:10 with distilled water. The diluted extracts (50 µL) were mixed with 200 µL of Folin–Ciocalteu reagent and 600 µL of a 20% sodium carbonate solution, and brought to 4 mL with distilled water. Reactions were incubated for 120 min at room temperature in the dark, and the absorbance was measured at 765 nm in a spectrophotometer. TPC was quantified in milligrams of gallic acid equivalent per liter of extract (GAE/L) with triplicate measurements.
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- Total phenolic content (milligrams of gallic acid equivalent per liter of extract [GAE/L]) in GPE_DG, GPE_CB, GPE_SCS, and GPE_DSCG extracts (Folin–Ciocalteu method).
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Researchers investigated the effects of different extraction solutions in the extraction process of natural compounds from grape pomace. Pomace from a mixture of Solaris, Muscat and Riesling white grapes (Cwielong-Olszewski vineyard, Balcarzowice, Opole Province, Poland) harvested at full ripeness (early September 2024) was extracted with aqueous solutions (2% w/w) of decyl glucoside (DG), cocamidopropyl betaine (CB), sodium coco-sulfate (SCS), and disodium cocoyl glutamate (DSCG). All solutions contained a mixture of benzyl alcohol, benzoic acid, dehydroacetic Acid, and tocopherol (0.5% w/w) as preservative. The grape pomace (400 g) was ground, mixed with 100 g of the extraction solutions, stirred at 380 rpm for 20 min, and vacuum-filtered (0.45 μm pore size; polyethersulfone membrane). The filtrates were designated according to the composition of the employed extraction solutions (i.e. DG: GPE_DG; CB: GPE_CB; SCS: GPE_SCS; DSCG: GPE_DSCG). The total phenolic content (TPC) of the different extracts was measured using the Folin–Ciocalteu (FC) method, and quantified in milligrams of gallic acid equivalent per liter of extract (GAE/L). What is the expected outcome, in terms of TPC, for the GPE_DSCG group, compared with the GPE_SCS group?
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The total phenolic content (TPC) values demonstrated that the GPE_DSCG group yielded a higher phenolic content than the the GPE_SCS group.
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- Grape pomace is a by-product obtained from the wine industry, with a high content of bioactive molecules, especially phenolic compounds.
- Sodium Coco-Sulfate represents anionic surfactants derived from coconuts with a negatively charged head group.
- Disodium Cocoyl Glutamate is a biodegradable anionic surfactant produced from L-glutamic acid (an amino acid) and vegetable fatty acids from coconut oil.
- Cocamidopropyl Betaine is a quaternary ammonium salt of natural origin that is widely used in cosmetic and skincare products as surfactant and for viscosity control.
- Decyl Glucoside represents non-ionic surfactants from alkyl polyglucosides, which have a glucose head group derived from corn, and a fatty alcohol tail group that is derived mainly from palm kernel oil.
|
[{"label":"RBK Item","value":"- Grape pomace is a by-product obtained from the wine industry, with a high content of bioactive molecules, especially phenolic compounds."},{"label":"Title","value":"Grapevine Wastes: A Rich Source of Antioxidants and Other Biologically Active Compounds"},{"label":"URL","value":"https://www.mdpi.com/2076-3921/11/2/393"},{"label":"Date","value":"February 15, 2022"},{"label":"Justification (\"Paywalled\", \"OA\", \"Other (justify)\")","value":"OA"},{"label":"RBK Item","value":"- Cocamidopropyl Betaine is a quaternary ammonium salt of natural origin that is widely used in cosmetic and skincare products as surfactant and for viscosity control."},{"label":"Title","value":"Safety assessment of cocamidopropyl betaine, a cosmetic ingredient"},{"label":"URL","value":"https://link.springer.com/article/10.1007/s43188-024-00243-2"},{"label":"Date","value":"May 21, 2024"},{"label":"Justification (\"Paywalled\", \"OA\", \"Other (justify)\")","value":"Paywalled version is the one cited by the paper"}]
|
Chemistry
|
Physical chemistry
|
Numerical Values
|
Experimental observation of quantum mechanical fluorine tunnelling
|
https://www.nature.com/articles/s41467-025-59008-6
|
April 29, 2025
|
Potassium fluoride (KF) targets were produced from dry KF powder using a hydraulic lab press. Filling of the pressing die and removal of the KF targets were carried out under an argon atmosphere inside a glove box in order to prevent contact of the highly hygroscopic material with atmospheric water. Matrix-isolation experiments were carried out in a custom-built vacuum chamber equipped with a cold-head, a helium compressor unit, and a gilded copper plate (matrix support) mounted on the cold-head. The device was held at a temperature of 5 K during experiments. Over the course of an experiment the vacuum chamber was kept at pressures between 3 ⋅ 10−7 and 1 ⋅ 10−6 mbar using an oil diffusion pump. For laser-ablation, pulses of a Nd:YAG laser (1064 nm) were aligned through a hole in the matrix support and focused on the potassium fluoride target. The KF targets were mounted on a target holder and rotated using a magnetically coupled electric motor. A gas inlet next to the target holder connected to a gas line via a needle valve allowed for the controlled co-deposition of gas mixtures with laser-ablated material. In a typical experiment potassium fluoride was evaporated using laser pulses at a rate of 1 Hz and co-deposited with Ne/F2 (99:1) gas mixtures at 5 K. The deposits were accumulated over the course of 3–4 hours at flow rates between 1–1.4 mbar L min−1. After deposition, the matrix support was rotated by 90∘ to measure IR spectra in reflection mode. IR spectra with a resolution of ≤0.1 cm−1 were recorded using a Bruker Vertex 80v vacuum FTIR spectrometer. A transfer optic was used to guide the IR measurement beam to the sample and to align the beam reflected by the matrix support to the detector of the instrument. Annealing of the deposits was facilitated by a heater cartridge built into the cold head. LEDs of 273 and 730 nm wavelengths were used for irradiation of the deposits.
|
- FTIR spectra of the Ne matrix containing fluorine-rich anions were recorded at 5 K in the 500–580 and 830–870 cm⁻¹ regions with a resolution ≤0.1 cm⁻¹, immediately after 3–4 h co-deposition and after subsequent UV (273 nm) and red (730 nm) irradiation. From these spectra, the wavenumber (cm⁻¹) of the band assigned to [F₅]⁻ was measured.
|
Researchers laser-ablated potassium fluoride (KF) with a Nd:YAG laser (1064 nm, 1 Hz) and co-deposited the ablated material with a Ne/F₂ (99:1) gas mixture onto a gold-plated copper support held at 5 K under vacuum conditions of 3×10⁻⁷–1×10⁻⁶ mbar. The co-deposition proceeded for 3–4 hours, generating multiple fluorine-rich anions, including [F₅]⁻, in the neon matrix. Infrared spectra were recorded at a resolution of ≤0.1 cm⁻¹ after deposition, followed by UV irradiation at 273 nm and red-light irradiation at 730 nm. What is the predicted FTIR band of [F₅]⁻ under these conditions?
|
FTIR band of [F₅]⁻= 851 cm-1 -> [765,9-936,1] cm−1.
|
-[F5]−: The pentafluoride anion is a very weakly bound complex, rendering its experimental characterization challenging.
- The first fragmental evidence of the formation of an [F5]− ion was reported in 2000 by Artau et al., who observed a weak signal of m/z=95 in mass spectra while investigating the bond dissociation energies of [F3]− (m/z=57) in the gas phase.
- it was hypothesized that only the V-shaped structure of [F5]− might be stabilized by neighbouring cationic species in the neon matrix21 – an hypothesis that could not been proven up to date.
|
[{"label":"RBK Item","value":"- The first fragmental evidence of the formation of an [F5]− ion was reported in 2000 by Artau et al., who observed a weak signal of m/z=95 in mass spectra while investigating the bond dissociation energies of [F3]− (m/z=57) in the gas phase."},{"label":"Title","value":"Bond Dissociation Energy in Trifluoride Ion"},{"label":"URL","value":"https://pubs.acs.org/doi/abs/10.1021/ja001613e"},{"label":"Date","value":"October 18, 2000"},{"label":"Justification (\"Paywalled\", \"OA\", \"Other (justify)\")","value":"Paywalled"},{"label":"RBK Item","value":"- it was hypothesized that only the V-shaped structure of [F5]− might be stabilized by neighbouring cationic species in the neon matrix21 – an hypothesis that could not been proven up to date."},{"label":"Title","value":"Fluorine-Rich Fluorides: New Insights into the Chemistry of Polyfluoride Anions"},{"label":"URL","value":"https://onlinelibrary.wiley.com/doi/abs/10.1002/anie.201502624"},{"label":"Date","value":"Jun 03, 2015"},{"label":"Justification (\"Paywalled\", \"OA\", \"Other (justify)\")","value":"OA"}]
|
Biology
|
Reproductive Biology
|
MCQ
|
CCDC89 is required for optimal sperm motility and male fertility in mammals
|
https://pmc.ncbi.nlm.nih.gov/articles/PMC12548035/
|
Jul 1, 2025
|
To test the requirement of CCDC89 for male fertility, two murine mutants were developed on a C57BL/6J background using CRISPR/Cas9: a knockout (KO) model (lacking the gene's single exon) and an E297D point mutant (PM) model. Heterozygous founder mice were identified by Sanger sequencing and inter-crossed to generate homozygous KO, PM, and wild-type (WT) males. Animals were aged to two distinct time points: 3 months (10–14 weeks) or 6 months (22–24 weeks). Following euthanasia, testes were dissected, fixed in Bouin’s solution for 5 hours, and processed for histological assessment. Testis sections were stained with Periodic Acid-Schiff (PAS) reagents to visualize acrosomal staging, and round spermatid numbers were counted in circular-profile stage VIII seminiferous tubules using the PAS-stained testis sections (n=10 tubules/animal, n≥5/genotype).
|
- Round spermatid counts in Stage VIII tubules across mouse models (Knockout (KO), point mutant (PM), and wild-type (WT) at 3 and 6 months.
|
To test the requirement of CCDC89 for male fertility, two murine mutants were developed on a C57BL/6J background using CRISPR/Cas9: a knockout (KO) model (lacking the gene's single exon) and an E297D point mutant (PM) model. Heterozygous founder mice were identified by Sanger sequencing and inter-crossed to generate homozygous KO, PM, and wild-type (WT) males. Animals were aged to two distinct time points: 3 months (10–14 weeks) or 6 months (22–24 weeks). Following euthanasia, testes were dissected, fixed in Bouin’s solution for 5 hours, and processed for histological assessment. Testis sections were stained with Periodic Acid-Schiff (PAS) reagents to visualize acrosomal staging, and round spermatid numbers were counted in circular-profile stage VIII seminiferous tubules using the PAS-stained testis sections (n=10 tubules/animal, n≥5/genotype). Which of the following outcomes best describes the findings of this quantification?
A. Round spermatid counts per tubule were significantly lower in both KO and PM males when compared to WT at both 3 and 6 months.
B. Round spermatid counts per tubule were significantly lower in KO males when compared to either WT or PM males at both 3 and 6 months.
C. Round spermatid counts per tubule were significantly lower in PM males when compared to either WT or KO males at both 3 and 6 months.
D. Round spermatid counts per tubule were comparable among WT, KO, and PM males at both 3 and 6 months.
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C. Round spermatid counts per tubule were significantly lower in PM males when compared to either WT or KO males at both 3 and 6 months.
|
- Numerous CCDC family members are enriched within the testis and play essential roles in sperm formation and function.
- CCDC89 was identified as a candidate human male fertility gene through the detection of a genetic variant in two infertile men with azoospermia.
|
[{"label":"RBK Item","value":"Numerous CCDC family members are enriched within the testis and play essential roles in sperm formation and function."},{"label":"Title","value":"Coiled-Coil Domain-Containing (CCDC) Proteins: Functional Roles in General and Male Reproductive Physiology"},{"label":"URL","value":"https://link.springer.com/article/10.1007/s43032-021-00595-2"},{"label":"Date","value":"May 03, 2021"},{"label":"Justification (\"Paywalled\", \"OA\", \"Other (justify)\")","value":"Paywalled"},{"label":"RBK Item","value":"CCDC89 was identified as a candidate human male fertility gene through the detection of a genetic variant in two infertile men with azoospermia."},{"label":"Title","value":"Diverse monogenic subforms of human spermatogenic failure"},{"label":"URL","value":"https://pmc.ncbi.nlm.nih.gov/articles/PMC9792524/"},{"label":"Date","value":"Dec 26, 2022"},{"label":"Justification (\"Paywalled\", \"OA\", \"Other (justify)\")","value":"OA"}]
|
Biology
|
Immunology
|
Free-Format Question
|
A20 restriction of nitric oxide production restores macrophage bioenergetic balance
|
https://www.biorxiv.org/content/10.1101/2025.10.26.684676v1
|
October 27, 2025
|
Our current research focuses on understanding the role of the protein A20, also known as TNF-α-induced protein 3 (TNFAIP3), before and during infection. A20Flox/Flox mice were interbred with ROSA/ER-Cre mice, and from the resulting A20Flox/Flox ROSA/ER-Cre+, A20Flox/+ ROSA/ER-Cre-, and A20Flox/Flox ROSA/ER-Cre- mice, bone marrow-derived macrophages (BMDMs) were generated. Next, A20 was deleted from A20Flox/Flox ROSA/ER-Cre+, adding 60nM 4-hydroxytamoxifen (4-OHT) 2 days before harvesting BMDMs. The resulting BMDM cells obtained after A20 deletion are called A20tiKO BMDMs. BMDMs obtained from Cre-negative BMDMs (A20Flox/+ ROSA/ER-Cre-) are called A20WT. To stimulate BMDMs, the following ligands and concentrations were used: a) lipopolysaccharide 100 ng/ml; b) poly(I:C) HMW 20 ug/ml; c) Pam3CSK4 1 ug/ml; d) CpG-A 2 uM; e) CpG-B 250 nM; f) Gardiquimod 1ug/ml; g) PolyU (complexed with lipofectamine) 0.5 ug/ml; h) flagellin (from S. typhimurium) 2 ug/ml (Invivogen). Lactate levels in BDMDs (A20WTs and A20tiKO) were measured 24 hrs after stimulations. Culture supernatants from stimulated macrophages were briefly centrifuged to remove any cell debris and lactate secretion were measured using a colourimetric Lactate Assay kit (BioVision).
|
- Lactate levels in BDMDs (A20WTs and A20tiKO) following 24 hours treatment with lipopolysaccharide 100 ng/ml.
- Lactate levels in BDMDs (A20WTs and A20tiKO) following 24 hours treatment with poly(I:C) HMW 20 ug/ml.
- Lactate levels in BDMDs (A20WTs and A20tiKO) following 24 hours treatment with Pam3CSK4 1 ug/ml.
- Lactate levels in BDMDs (A20WTs and A20tiKO) following 24 hours treatment with CpG-A 2 uM.
- Lactate levels in BDMDs (A20WTs and A20tiKO) following 24 hours treatment with CpG-B 250 nM.
- Lactate levels in BDMDs (A20WTs and A20tiKO) following 24 hours treatment with Gardiquimod 1ug/ml.
- Lactate levels in BDMDs (A20WTs and A20tiKO) following 24 hours treatment with PolyU (complexed with lipofectamine) 0.5 ug/ml.
- Lactate levels in BDMDs (A20WTs and A20tiKO) following 24 hours treatment with flagellin (from S. typhimurium) 2 ug/ml.
|
We are interested in understanding the role of the protein A20, also known as TNF-α-induced protein 3 (TNFAIP3), during infection. To do this, A20Flox/Flox mice were interbred with ROSA/ER-Cre mice, and from the resulting A20Flox/Flox ROSA/ER-Cre+, A20Flox/+ ROSA/ER-Cre-, and A20Flox/Flox ROSA/ER-Cre- mice, bone marrow-derived macrophages (BMDMs) were generated. Next, A20 was deleted from A20Flox/Flox ROSA/ER-Cre+ by adding 60nM 4-hydroxytamoxifen (4-OHT) 2 days before harvesting BMDMs. The resulting BMDM cells obtained after A20 deletion were called A20tiKO BMDMs. BMDMs obtained from Cre-negative BMDMs (A20Flox/+ ROSA/ER-Cre-) as controls were called A20WT. If we stimulated A20WT and A20tiKO BMDMs with the following ligands: lipopolysaccharide 100 ng/ml, poly(I:C) HMW 20 ug/ml, Pam3CSK4 1 ug/ml, CpG-A 2 uM, CpG-B 250 nM, Gardiquimod 1ug/ml, PolyU (complexed with lipofectamine) 0.5 ug/ml and flagellin (from S. typhimurium) 2 ug/ml and measured the lactate levels in culture supernatant after removing cell debris, which four ligands will produce the largest lactate levels from A20WT and A20tiKO BMDMs cells?
|
The four ligands will be lipopolysaccharide 100 ng/ml, Pam3CSK4 1 ug/ml, Gardiquimod 1ug/ml and CpG-B 250 nM.
|
- Activation of immune cells is associated with a rapid burst in glycolytic activity along with mitochondrial remodelling.
- LPS stimulation of these cells (macrophages) triggers a glycolytic surge that provides energy for cytokine transcription, translation, and secretion.
- The ubiquitin editing protein A20, also known as TNF-α-induced protein 3 (TNFAIP3), is a susceptibility gene for multiple diseases, including rheumatoid arthritis, Crohn’s disease, systemic lupus erythematosus, psoriasis, multiple sclerosis, scleroderma, and asthma.
|
[{"label":"RBK Item","value":"- Activation of immune cells is associated with a rapid burst in glycolytic activity along with mitochondrial remodelling."},{"label":"Title","value":"Mitochondrial Dynamics Controls T Cell Fate through Metabolic Programming"},{"label":"URL","value":"https://pubmed.ncbi.nlm.nih.gov/27293185/"},{"label":"Date","value":"June, 30, 2016"},{"label":"Justification (\"Paywalled\", \"OA\", \"Other (justify)\")","value":"OA"},{"label":"RBK Item","value":"- The ubiquitin editing protein A20, also known as TNF-α-induced protein 3 (TNFAIP3), is a susceptibility gene for multiple diseases, including rheumatoid arthritis, Crohn’s disease, systemic lupus erythematosus, psoriasis, multiple sclerosis, scleroderma, and asthma "},{"label":"Title","value":"A20: linking a complex regulator of ubiquitylation to immunity and human diseas"},{"label":"URL","value":"https://pmc.ncbi.nlm.nih.gov/articles/PMC3582397/"},{"label":"Date","value":"October 12, 2012"},{"label":"Justification (\"Paywalled\", \"OA\", \"Other (justify)\")","value":"OA"}]
|
Biology
|
Lipid Biochemistry
|
Free-Format Question
|
Loss of PREPL alters lipid homeostasis due to mitochondrial defects
|
https://www.biorxiv.org/content/10.1101/2025.10.28.685080v1
|
October 28, 2025
|
We are interested in the effect of the PREPL on lipid metabolism. To study this, we performed Lipid droplet staining and high-content microscopy on PREPL-/- HEK293T cells and wild-type HEK293T cells (wtHEK293T) as a control. To do this, PREPL-/- and control HEK293T cells with cell density 15,000 cells/well were plated on poly-D-lysine (Merck Millipore) coated 96-well Cell Carrier Ultra microplate (PerkinElmer). The cells were washed thrice with DPBS (pH 7.4; Thermo Fisher Scientific) and fixed using 4% paraformaldehyde (PFA) for 30 minutes. Lipid droplet staining was performed by first diluting LipidSpot 488 (Biotium) stain to 1X in DPBS, followed by staining the cells with the resulting staining solution for 30 minutes in a light-protected environment. This was followed by DAPI (nuclear) staining for 10-20 minutes. Fluorescence was measured using a high-content screening microscope, Operettan (CLS+Twister; PerkinElmer), and lipid droplet size and number were quantified using Harmony 4.9 software (PerkinElmer).
|
- Cell number of PREPL-/- HEK293T cells after DAPI staining (10 - 20 minutes) and lipid droplet staining (30 minutes in the dark) using diluted 1X LipidSpot 488 (Biotium) stain for 30 minutes in the dark.
- Cell number of wtHEK293T cells after DAPI staining (10 - 20 minutes) and lipid droplet staining (30 minutes in the dark) using diluted 1X LipidSpot 488 (Biotium) stain for 30 minutes in the dark.
- Lipid Spots number of PREPL-/- HEK293T cells after DAPI staining (10 - 20 minutes) and lipid droplet staining (30 minutes in the dark) using diluted 1X LipidSpot 488 (Biotium) stain for 30 minutes in the dark.
- Lipid Spots number of wtHEK293T cells after DAPI staining (10 - 20 minutes) and lipid droplet staining (30 minutes in the dark) using diluted 1X LipidSpot 488 (Biotium) stain for 30 minutes in the dark.
- Quantification of lipid spot numbers/cell in PREPL-/- HEK293T cells after DAPI staining (10 - 20 minutes) and lipid droplet staining (30 minutes in the dark) using diluted 1X LipidSpot 488 (Biotium) stain for 30 minutes in the dark.
- Quantification of lipid spot numbers/cell in wtHEK293Tcells after DAPI staining (10 - 20 minutes) and lipid droplet staining (30 minutes in the dark) using diluted 1X LipidSpot 488 (Biotium) stain for 30 minutes in the dark.
|
We are interested in understanding the effect of the PREPL on lipid metabolism. We performed Lipid droplet staining and high-content microscopy on PREPL-/- HEK293T cells and wild-type HEK293T cells (wtHEK293T) as a control. PREPL-/- and control HEK293T cells with cell density 15,000 cells/well were plated on poly-D-lysine-coated 96-well Cell Carrier Ultra microplate. The cells were washed thrice with DPBS (pH 7.4) and fixed using 4% paraformaldehyde (PFA) for 30 minutes. We then perform Lipid droplet staining by first diluting LipidSpot 488 (Biotium) stain to 1X in DPBS, followed by staining the cells with the resulting staining solution for 30 minutes in a light-protected environment. This was followed by DAPI (nuclear) staining for 10-20 minutes. If we performed 4 independent experiments and calculated the cell and lipid spot numbers in both PREPL-/- HEK293T cells and wtHEK293T cells, and quantified the ratio of lipid spot numbers/cell, what would be the expected individual ratio calculated in each wtHEK293T and PREPL-/- HEK293T cells in two decimal places?
|
LipidSpots/Cell = [13.74 - 15.96] for PREPL-/- HEK293T cells derived from 14.85. Note: CI reported ±1.11. LipidSpots/Cell = [8.26 - 9.42] for wtHEK293T cells derived from 8.84. Note: CI reported ±0.58
|
- PREPL belongs to the serine hydrolase superfamily and has been implicated in the regulation of the
secretory pathway and mitochondrial respiration.
- PREPL has its highest expression in the brain, followed by intermediate levels in neuroendocrine cells, the kidney and muscle.
|
[{"label":"RBK Item","value":"- PREPL belongs to the serine hydrolase superfamily and has been implicated in the regulation of the\nsecretory pathway and mitochondrial respiration."},{"label":"Title","value":"Prolyl endopeptidase-like is a (thio)esterase involved in mitochondrial respiratory chain function"},{"label":"URL","value":"https://pmc.ncbi.nlm.nih.gov/articles/PMC8634043/"},{"label":"Date","value":"November 14, 2021"},{"label":"Justification (\"Paywalled\", \"OA\", \"Other (justify)\")","value":"OA"}]
|
Chemistry
|
Physical Chemistry
|
Numerical Values
|
An Advanced Probe of Local Electric Field to Understand Electrode/Electrolyte Interface during Oxygen Evolution
|
https://chemrxiv.org/engage/chemrxiv/article-details/68f8b4ac5dd091524fc96dc7
|
October 24, 2025
|
Researchers investigated the oxygen evolution reaction (OER) kinetics of an iridium oxide (IrOx) catalyst using a rotating disk electrode (RDE) system. The working electrode consisted of IrOx coated on a titanium (Ti) disk, used as the working electrode in a three-electrode electrochemical cell with a platinum counter electrode and a Hg/Hg₂Cl₂ reference electrode, whose potential was converted to the reversible hydrogen electrode (RHE) scale. Experiments were performed in 0.1 M phosphate-based electrolytes at three pH conditions: acidic (0.1 M H₃PO₄, pH 1.5), neutral (0.1 M K-phosphate, pH 7), and alkaline (0.1 M K-phosphate, pH 13), all at 298 K. Linear sweep voltammetry was carried out under electrode rotation at several disk-rotation speeds in each electrolyte, with a scan rate of 1 mV s⁻¹. Kinetic current densities were obtained from the rotating disk voltammograms by Koutecký–Levich analysis, and overpotentials and kinetic current densities were used to construct Tafel plots (overpotential vs. logarithm of kinetic current density) for each pH condition.
|
- Applied potential (V vs RHE), recorded during linear sweep voltammetry at 298 K for the IrOx/Ti rotating disk electrode in 0.1 M H₃PO₄ (pH 1.5), 0.1 M K-phosphate (pH 7), or 0.1 M K-phosphate (pH 13), with a scan rate of −1 mV s⁻¹ and disk-rotation speeds between 1600 and 4900 rpm.
- Kinetic current density (mA cm⁻²), obtained at each applied potential from RDE voltammograms recorded under the same conditions (298 K, −1 mV s⁻¹, 1600–4900 rpm) by Koutecký–Levich analysis of the rotation-dependent current and normalized by the geometric area of the Ti disk electrode.
- Tafel slope (mV dec⁻¹), determined for each electrolyte and pH by linear fitting of the overpotential versus log₁₀(kinetic current density) in the kinetically controlled potential region of the OER at 298 K.
- pH of the electrolyte, set by the composition of the 0.1 M H₃PO₄ (pH 1.5), 0.1 M K-phosphate (pH 7), or 0.1 M K-phosphate (pH 13) solutions used in the RDE measurements at 298 K.
|
Researchers evaluated the oxygen evolution reaction (OER) kinetics of an IrOx/Ti rotating disk electrode (RDE) in phosphate-based electrolytes at three different pH levels: 1.5 (0.1 M H₃PO₄), 7 (0.1 M K-phosphate), and 13 (0.1 M K-phosphate), all measured at 298K. Tafel analysis was used to determine the slope of the potential–current relationship, allowing for a comparison of catalytic efficiency across the different pH conditions. What would be the measured Tafel slope (in mV dec⁻¹) for the OER at pH 13?
|
42 V dec⁻¹ -> [38 - 46 mV dec⁻¹] Fallback used: +/- 10%
|
- Water electrolysis that converts ubiquitous H2O into an energy carrier of H2 will play an indispensable role in achieving a sustainable society.1 While H2 is produced at the cathode, the coupled anodic half-reaction of oxygen evolution reaction (OER) requires large overpotential and causes significant efficiency loss.
- Iridium oxide (IrOx) has been reported to exhibit the highest activity toward the OER across a wide pH range.
- in non-extreme pH conditions where buffering species is essential to achieve high OER efficiency, OER kinetics over IrOx varied with the buffer identity and composition in electrolyte, thus the optimal electrolyte condition depends on the target current density.
- The chemical composition and charge accumulation at the electrode/electrolyte interface are the subject of consideration, which have been detailed in many theoretical studies.
|
[{"label":"RBK Item","value":"- Water electrolysis that converts ubiquitous H2O into an energy carrier of H2 will play an indispensable role in achieving a sustainable society.1 While H2 is produced at the cathode, the coupled anodic half-reaction of oxygen evolution reaction (OER) requires large overpotential and causes significant efficiency loss."},{"label":"Title","value":"A review on fundamentals for designing oxygen evolution electrocatalysts"},{"label":"URL","value":"https://pubs.rsc.org/en/content/articlelanding/2021/xx/c9cs00607a/unauth"},{"label":"Date","value":"May 5, 202"},{"label":"Justification (\"Paywalled\", \"OA\", \"Other (justify)\")","value":"Paywalled"},{"label":"RBK Item","value":"- Iridium oxide (IrOx) has been reported to exhibit the highest activity toward the OER across a wide pH range."},{"label":"Title","value":"Thrifting iridium for hydrogen"},{"label":"URL","value":"https://www.science.org/doi/abs/10.1126/science.adv4929"},{"label":"Date","value":"Feb 13, 2025"},{"label":"Justification (\"Paywalled\", \"OA\", \"Other (justify)\")","value":"Paywalled"},{"label":"RBK Item","value":"- in non-extreme pH conditions where buffering species is essential to achieve high OER efficiency, OER kinetics over IrOx varied with the buffer identity and composition in electrolyte, thus the optimal electrolyte condition depends on the target current density."},{"label":"Title","value":"Delivering the Full Potential of Oxygen Evolving Electrocatalyst by Conditioning Electrolytes at Near-Neutral pH"},{"label":"URL","value":"https://chemistry-europe.onlinelibrary.wiley.com/doi/full/10.1002/cssc.202002813"},{"label":"Date","value":"Feb 22, 2021"},{"label":"Justification (\"Paywalled\", \"OA\", \"Other (justify)\")","value":"Paywalled"}]
|
Biology
|
Plankton Ecology
|
MCQ
|
Responses of the Natural Phytoplankton Assemblage to Patagonian Dust Input and Anthropogenic Changes in the Southern Ocean
|
https://agupubs.onlinelibrary.wiley.com/doi/full/10.1029/2024EF005762
|
June 4, 2025
|
Scientists conducted a 5-day shipboard incubation experiment to test how Patagonia dust input under predicted future (year 2100) temperature and pH conditions influences the net growth rate of natural phytoplankton communities from the Southern Ocean. The pythoplankton samples were collected onboard the French R.V. Marion Dufresne II in the Indian sector of the SO during the summer 2022 (February) from the Polar Frontal Zone (PFZ) (at 47°40S, 58°00'E; sampled on 02/16/2022). Seawater was collected (depth of 15 m) using an ultra-cleaned PTFE diaphragm VA-P08 pump (flow rate of 15 L min−1). The seawater was filtered through a 200 μm mesh (nylon). 100 L of seawater was distributed into cleaned 10 L polycarbonate (PC) bottles. Acidification was simulated by taking 500 mL of each 10 L bottle, where it was bubbled with pure CO2 for 2 minutes, returned to the bottle, then the full 10 L was bubbled with 800 ppm CO2 until pH stabilized at ~7.80. Bottles were placed in a deck incubator with seawater maintained +3 °C above ambient by a thermostat and temperature controller; temperature was checked twice daily. Patagonian soil dust was dried, ground and weighed to 1 mg/L and 2 mg/L, then suspended in a small volume of filtered seawater, gently vortexed, and then added to 10L bottles (shaken to disperse). Control bottles under future T and pH conditions, without dust were also included. Once dust was added and pH/temp adjustments made, 2 L aliquots were transferred for incubation on deck for 5 days (natural sunlight filtered). Picophytoplankton abundances were measured by flow cytometry at the start of incubation and day 5. Net growth rate was calculated as μ/d=ΔLn(N)/t.
|
- Net growth rates (µ d⁻¹, calculated as µ = Δln(N)/t) of picophytoplankton in the Polar Frontal Zone (PFZ) taken from the Southern Ocean under predicted future conditions (+3 °C, pH≈7.8) with and without Patagonia dust (1 mg/L and 2 mg/L).
|
Scientists conducted a 5-day shipboard incubation experiment to test how Patagonia dust input under predicted future (year 2100) temperature and pH conditions influences the net growth rate of natural phytoplankton communities from the Southern Ocean. The pythoplankton samples were collected onboard the French R.V. Marion Dufresne II in the Indian sector of the SO during the summer 2022 (February) from the Polar Frontal Zone (PFZ) (at 47°40S, 58°00'E; sampled on 02/16/2022). Seawater was collected (depth of 15 m) using an ultra-cleaned PTFE diaphragm VA-P08 pump (flow rate of 15 L min−1). The seawater was filtered through a 200 μm mesh (nylon). 100 L of seawater was distributed into cleaned 10 L polycarbonate (PC) bottles. Acidification was simulated by taking 500 mL of each 10 L bottle, where it was bubbled with pure CO2 for 2 minutes, returned to the bottle, then the full 10 L was bubbled with 800 ppm CO2 until pH stabilized at ~7.80. Bottles were placed in a deck incubator with seawater maintained +3 °C above ambient by a thermostat and temperature controller; temperature was checked twice daily. Patagonian soil dust was dried, ground and weighed to 1 mg/L and 2 mg/L, then suspended in a small volume of filtered seawater, gently vortexed, and then added to 10L bottles (shaken to disperse). Control bottles under future T and pH conditions, without dust were also included. Once dust was added and pH/temp adjustments made, 2 L aliquots were transferred for incubation on deck for 5 days (natural sunlight filtered). Picophytoplankton abundances were measured by flow cytometry at the start of incubation and day 5. Net growth rate per day was calculated as μ=ΔLn(N)/t.
Which of the following outcomes is most likely to be observed?
A) Dust addition under future temperatures and pH caused a strong increase in picophytoplankton growth compared to dust-free controls
B) Warming and acidification alone led to the highest picophytoplankton growth, with no stimulation from dust
C) Picophytoplankton growth decreased under future temperature and pH treatments with no change wth the addition of dust
D) Dust addition reduced picophytoplankton growth compared with dust-free controls under the same future conditions
|
B) Warming and acidification alone led to the highest picophytoplankton growth, with no stimulation from dust
|
- Patagonian dust a source of iron-rich dust that can provide essential nutrients for the Southern Ocean region.
- Future ocean conditions are projected to include warmer temperatures (+3 °C) and lower pH (~7.8) by 2100.
- The PFZ is characterized by significant seasonal variations, with a predominance of smaller species such as cyanobacteria and coccolithophorids.
|
[{"label":"RBK Item","value":"- Patagonian dust is a source of iron-rich dust that can provide essential nutrients for the Southern Ocean region."},{"label":"Title","value":"Observed 20th century desert dust variability: impact on climate and biogeochemistry"},{"label":"URL","value":"https://acp.copernicus.org/articles/10/10875/2010/"},{"label":"Date","value":"November 19, 2010"},{"label":"Justification (\"Paywalled\", \"OA\", \"Other (justify)\")","value":"OA"},{"label":"RBK Item","value":"- Future ocean conditions are projected to include warmer temperatures (+3 °C) and lower pH (~7.8) by 2100."},{"label":"Title","value":"Climate change and Southern Ocean ecosystems I: How changes in physical habitats directly affect marine biota."},{"label":"URL","value":"https://onlinelibrary.wiley.com/doi/abs/10.1111/gcb.12623"},{"label":"Date","value":"May 7, 2014"},{"label":"Justification (\"Paywalled\", \"OA\", \"Other (justify)\")","value":"OA"},{"label":"RBK Item","value":"- The PFZ is characterized by significant seasonal variations, with a predominance of smaller species such as cyanobacteria and coccolithophorids"},{"label":"Title","value":"Iron and silicic acid concentrations regulate Si uptake north and south of the Polar Frontal Zone in the Pacific Sector of the Southern Ocean"},{"label":"URL","value":"https://www.sciencedirect.com/science/article/abs/pii/S0967064500000709"},{"label":"Date","value":"2000"},{"label":"Justification (\"Paywalled\", \"OA\", \"Other (justify)\")","value":"Paywalled"}]
|
Biology
|
Cancer Biology
|
MCQ
|
EGFR-targeted and MMP-activated membranolytic peptides derived from Polybia paulista MP1 kill cancer cells specifically in vitro and reduce tumour growth in vivo
|
https://www.biorxiv.org/content/10.1101/2025.10.07.680850v1
|
October 7, 2025
|
Researchers determined the IC50 doses of the membrane-disrupting peptide Mastoparan-1 (MP1) and MP1 fusion variants against cancer cell lines. The details of each peptide variant are described as follows.
1) Peptide name: MP1, Description: the original MP1 peptide, Sequence: IDWKKLLDAAKQIL
2) Peptide name: N-EGFR-MP1, Description: MP1 that was N-terminally linked with the sequence that binds to the extracellular domain of the epidermal growth factor receptor (EGFR) using GG linker, Sequence: YHWYGYTPENVIGGIDWKKLLDAAKQIL
3) Peptide name: N-EGFR-MMP-MP1, Description: MP1 that was N-terminally linked with the matrix metalloproteinase 2 (MMP-2) cleavage recognition sequence, and the EGFR binding sequence, Sequence: YHWYGYTPENVIGPLGIAGQIDWKKLLDAAKQIL
4) Peptide name: C-EGFR-MP1, Description: MP1 that was C-terminally linked with the EGFR binding sequence, using GG linker, Sequence: IDWKKLLDAAKQILGGYHWYGYTPENVI
5) Peptide name: C-EGFR-MMP-MP1, Description: MP1 that was C-terminally linked with the MMP-2 cleavage site and the EGFR binding sequence, Sequence: IDWKKLLDAAKQILGPLGIAGQYHWYGYTPENVI
A panel of human breast epithelial cell lines was evaluated, including two lines from a non-transformed origin (MCF-10A; HB2) and four cancer lines (BT-474; AU-565; MDA-MB-231; MDA-MB-468). MP1 and its fusion variants were synthesized by Bio-Synthesis Inc. (Lewisville, TX, USA). Cell lines were seeded in 96-well plates with Dulbecco's Modified Eagle Medium (DMEM) supplemented with 10% fetal calf serum (FCS) and 100 units/ml of penicillin/streptomycin at 10,000 cells per well and incubated in a humidified incubator with 5% CO2 at 37°C for 18 h. Then, the growth medium was removed, and cells were treated with various concentrations (0 – 250 µM) of each variant of MP1 for 24 h. After that, the growth medium containing MP-1 was removed, cells were then incubated with 0.5 mg/ml MTT reagent dissolved in PBS for 3 h. The PBS containing the reagent was then removed, the Formazan crystals (produced by the mitochondrial enzymes of viable cells) were dissolved in 500 µl isopropanol, and the absorbance was measured at 570 nm using a microplate spectrophotometer to obtain the percentage of cell survival and IC50 (µM) values.
|
- Absorbance at 570 nm of the dissolved Formazan crystals obtained from each cell line (MCF-10A, HB2, BT-474, AU-565, MDA-MB-468, and MDA-MB-231) after treating with different concentrations (0 – 250 µM) of each MP1 fusion variant (MP1, N-EGFR-MP1, N-EGFR-MMP-MP1, C-EGFR-MP1, and C-EGFR-MMP-MP1).
- The percentage of cell survival (%) from each cell line (MCF-10A, HB2, BT-474, AU-565, MDA-MB-468, and MDA-MB-231) after treating with different concentrations (0 – 250 µM) of each MP1 fusion variant (MP1, N-EGFR-MP1, N-EGFR-MMP-MP1, C-EGFR-MP1, and C-EGFR-MMP-MP1).
- The IC50 value (µM) from each cell line (MCF-10A, HB2, BT-474, AU-565, MDA-MB-468, and MDA-MB-231) after treating with different concentrations (0 – 250 µM) of each MP1 fusion variant (MP1, N-EGFR-MP1, N-EGFR-MMP-MP1, C-EGFR-MP1, and C-EGFR-MMP-MP1).
|
The membrane-disrupting peptide Mastoparan-1 (MP1) derived from the wasp Polybia paulista was previously reported to exhibit some degree of cancer-specific lytic activity. The researcher attempted to enhance the toxicity and cancer specificity of MP1 by adding 2 different functionalities to either the N-terminus or the C-terminus of MP1. The functionalities fused with MP1 are either the sequence that binds to the extracellular domain of the epidermal growth factor receptor (EGFR) linked by a GG linker, or the matrix metalloproteinase-2 (MMP-2) cleavage recognition sequence linked to the EGFR binding sequence. Therefore, there were 5 MP1 peptide variants in this experiment, detailed as follows.
1) Original MP1 peptide (MP1, IDWKKLLDAAKQIL)
2) MP1 that was N-terminally linked with EGFR binding sequence by GG linker (N-EGFR-MP1, YHWYGYTPENVIGGIDWKKLLDAAKQIL)
3) MP1 that was N-terminally linked with the MMP-2 cleavage site, and EGFR binding sequence (N-EGFR-MMP-MP1, YHWYGYTPENVIGPLGIAGQIDWKKLLDAAKQIL)
4) MP1 that was C-terminally linked with EGFR binding sequence by GG linker (C-EGFR-MP1, IDWKKLLDAAKQILGGYHWYGYTPENVI)
5) MP1 that was C-terminally linked with the MMP-2 cleavage site, and EGFR binding sequence (C-EGFR-MMP-MP1, IDWKKLLDAAKQILGPLGIAGQYHWYGYTPENVI)
The human breast epithelial cell lines used to examine the toxicity of these MP1 peptide variants are MCF-10A, HB2, BT-474, AU-565, MDA-MB-468, and MDA-MB-231.
The cell lines were treated with different doses of each MP1 variant (0 – 250 µM). After treatment, the MTT assay was performed, and the resulting absorbance measurements were used to calculate the percentage of cell survival relative to the untreated control. The dose-response curves were plotted to determine the IC50 value (µM) of each MP1 variant against each cell line. Which of the following outcomes is most likely?
A) Neither fusion peptide showed strikingly different efficacy in BT-474 cells compared to MP1.
B) Neither fusion peptide showed strikingly different efficacy in MCF-10A cells compared to MP1.
C) Neither fusion peptide showed strikingly different efficacy in MDA-MB-231 cells compared to MP1.
D) Neither fusion peptide showed strikingly different efficacy in HB2 cells compared to MP1.
|
B) Neither fusion peptide showed strikingly different efficacy in MCF-10A cells compared to MP1.
|
- Mastoparan-1 (MP1, [IDWKKLLDAAKQIL]) is a membranolytic peptide derived from the wasp Polybia paulista. MP1 was previously reported to have some degree of cancer-specific lytic activity.
- The epidermal growth factor receptor (EGFR) is over-expressed in a range of common cancers, including breast, colorectal, and lung, and is well established as both a target for therapeutic inhibition and a surface biomarker to direct binding of the therapeutics to cancer cells.
- The matrix metalloproteinase 2 (MMP-2) is frequently overexpressed in cancers, including in breast and colorectal. MMP-cleavage sites have been used to confer cancer-specific activation properties on various potential therapeutics.
|
[{"label":"RBK Item","value":"- Mastoparan-1 (MP1, [IDWKKLLDAAKQIL]) is a membranolytic peptide derived from the wasp Polybia paulista. MP1 was previously reported to have some degree of cancer-specific lytic activity."},{"label":"Title","value":"Antitumor effects, cell selectivity and structure–activity relationship of a novel antimicrobial peptide polybia-MPI"},{"label":"URL","value":"https://www.sciencedirect.com/science/article/abs/pii/S0196978108000454"},{"label":"Date","value":"June, 2008"},{"label":"Justification (\"Paywalled\", \"OA\", \"Other (justify)\")","value":"Paywalled"},{"label":"RBK Item","value":"- The epidermal growth factor receptor (EGFR) is over-expressed in a range of common cancers, including breast, colorectal, and lung, and is well established as both a target for therapeutic inhibition and a surface biomarker to direct binding of the therapeutics to cancer cells."},{"label":"Title","value":"Targeting EGFR of triple-negative breast cancer enhances the therapeutic efficacy of paclitaxel- and cetuximab-conjugated nanodiamond nanocomposite"},{"label":"URL","value":"https://www.sciencedirect.com/science/article/abs/pii/S1742706119300455"},{"label":"Date","value":"March 1, 2019"},{"label":"Justification (\"Paywalled\", \"OA\", \"Other (justify)\")","value":"Paywalled"},{"label":"RBK Item","value":"- The matrix metalloproteinase 2 (MMP-2) is frequently overexpressed in cancers, including in breast and colorectal. MMP-cleavage sites have been used to confer cancer-specific activation properties on various potential therapeutics."},{"label":"Title","value":"Matrix Metalloproteinase-Responsive Drug Delivery Systems"},{"label":"URL","value":"https://pubs.acs.org/doi/10.1021/acs.bioconjchem.3c00266"},{"label":"Date","value":"August 2, 2023"},{"label":"Justification (\"Paywalled\", \"OA\", \"Other (justify)\")","value":"Paywalled"}]
|
Biology
|
Cancer Biology
|
MCQ
|
Tumor-associated Macrophages protect Glioblastoma cells from ferroptosis by inducing the release of Ferritin-bound iron via exosomes
|
https://www.biorxiv.org/content/10.1101/2025.10.21.683804v1
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October 22, 2025
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The researchers investigated how the macrophage iron metabolism is altered in the presence of glioblastoma (GBM) cells. They grew murine bone marrow-derived macrophages (BMDMs) with GL261 cells, a GBM cell line derived from C57BL6 mice, in a transwell coculture system.
BMDMs were generated by collecting the bone marrow from the femurs and tibias from either male or female C57BL/6 mice, flushed with DMEM with GlutaMAX (ThermoFisher Scientific). The bone marrow was washed and run through a 70 μm cell strainer and cultured in non-tissue culture-treated Petri dishes in DMEM with GlutaMAX with the addition of 20% v/v conditioned media from L929 cells and 30% v/v FBS to serve as a source of M-CSF for differentiation of bone marrow progenitor cells into macrophages. Additional media was added to the Petri dish on day 3 and day 6. On day 7, the differentiation was confirmed by looking at the cell morphology, adherence to the Petri dish, and expression of macrophage-specific markers (F4/80 and CD11b).
In co-culture experiments, GL261 cells were cultured in a 12-well plate containing DMEM with GlutaMAX (ThermoFisher Scientific) with 10% fetal bovine serum (GeminiBio) and 1% Penicillin-Streptomycin (ThermoFisher Scientific). The BMDMs were cultured on transwell inserts of pore size 0.4 μm to facilitate the free exchange of secreted proteins and exosomes. Cells were maintained in a humidified tissue culture incubator with 5% CO2 at 37 °C for 24 hours.
After coculture, BMDMs were subjected to immunoblot analysis to determine the expression of H-ferritin (FTH1), L-ferritin (FTL), transferrin receptor (TFRC), and beta-actin, in comparison with BMDMs cultured alone. Briefly, cells were lysed using RIPA buffer (Sigma) and protease inhibitor cocktail (PIC, Sigma). Subsequently, total protein was quantified by BCA Protein Assay (Pierce), and equal amounts of protein were loaded onto a 4 to 20% Criterion TGX Precast Protein Gel (Bio-Rad). Proteins were transferred onto a PVDF membrane and probed for FTH1, FTL, and TFRC. A corresponding secondary antibody conjugated to HRP was used (1:5000, GE 175 Amersham), and the bands were visualized using ECL reagents (PerkinElmer) on an Amersham 176 Imager 600 (GE Amersham).
|
- Relative expression levels of H-ferritin (FTH1), L-ferritin (FTL), and transferrin receptor (TFRC) between BMDMs cocultured with GL261 cells and those cultured alone, and between BMDMs derived from male and female mice.
|
The researchers investigated how the macrophage iron metabolism is altered in the presence of glioblastoma (GBM) cells. They grew murine bone marrow-derived macrophages (BMDMs), obtained from either male or female mice, with GL261 cells (a GBM cell line derived from C57BL6 mice) in a transwell coculture system. After coculture for 24 hours, relative expression levels of H-ferritin (FTH1), L-ferritin (FTL), and transferrin receptor (TFRC) in BMDMs, cocultured with GL261 cells or cultured alone, were determined by immunoblot analysis using beta-actin as a loading control. Which of the following outcomes is most likely?
A) BMDMs cocultured with GL261 cells showed higher FTH1, FTL, and TFRC expressions than BMDMs cultured alone. Male BMDMs showed higher FTH1, FTL, and TFRC expressions than female BMDMs, in both culture alone and co-culture with GL261 cells.
B) BMDMs cocultured with GL261 cells showed higher FTH1, FTL, and TFRC expressions than BMDMs cultured alone. Female BMDMs showed higher FTH1, FTL, and TFRC expressions than male BMDMs, in both culture alone and co-culture with GL261 cells.
C) BMDM cocultured with GL261 cells showed higher FTH1 and FTL expressions than BMDMs cultured alone. Female BMDMs showed significantly higher TFRC expressions than male BMDMs in culture alone. But, in coculture with GL261 cells, male BMDMs showed higher TFRC expression.
D) BMDMs cocultured with GL261 cells showed higher FTH1 and FTL expressions than BMDMs cultured alone. Male BMDMs showed significantly higher TFRC expressions than female BMDMs in culture alone. But, in coculture with GL261 cells, female BMDMs showed higher TFRC expression.
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D) BMDMs cocultured with GL261 cells showed higher FTH1 and FTL expressions than BMDMs cultured alone. Male BMDMs showed significantly higher TFRC expressions than female BMDMs in culture alone. But, in coculture with GL261 cells, female BMDMs showed higher TFRC expression.
|
- Tumor-associated macrophages (TAMs) comprise up to 50 percent of the total tumor volume and are one of the most abundant cell populations in the tumor microenvironment (TME) of glioblastoma (GBM).
- TAMs play a significant role in maintaining iron homeostasis in the TME and can play a pivotal role in controlling ferroptotic stress in neoplastic cells.
- Cancer cells upregulate the expression of transferrin receptor (TFRC), a protein involved in iron uptake, and ferritin, a protein involved in cellular iron storage. In GBM, both transferrin receptor and ferritin are necessary for tumorigenesis.
- Due to the high iron levels in cancer cells, they are susceptible to ferroptosis, an iron-mediated form of cell death.
- Protein-bound ferric iron (Fe3+, stored within ferritin) is not directly involved in ferroptosis. As a result, ferritin can act as a ferroptosis suppressor by quenching available Fe2+ in the labile iron pool.
- GBM is a sexually dimorphic disease, with sexually dimorphic features in incidence, phenotype, response to therapy, and overall outcome. GBM is more frequent and aggressive in male patients.
- Sex difference in iron metabolism is thought to be a major contributor to the sexually dimorphic nature of GBM.
- Immunoblot or Western analysis is a method to detect protein expression.
|
[{"label":"RBK Item","value":"- Tumor-associated macrophages (TAMs) comprise up to 50 percent of the total tumor volume and are one of the most abundant cell populations in the tumor microenvironment (TME) of glioblastoma (GBM). "},{"label":"Title","value":"Tumor microenvironment in glioblastoma: Current and emerging concepts"},{"label":"URL","value":"https://academic.oup.com/noa/article/5/1/vdad009/7053170?login=false"},{"label":"Date","value":"February 23, 2023"},{"label":"Justification (\"Paywalled\", \"OA\", \"Other (justify)\")","value":"OA"},{"label":"RBK Item","value":"- TAMs play a significant role in maintaining iron homeostasis in the TME and can play a pivotal role in controlling ferroptotic stress in neoplastic cells."},{"label":"Title","value":"The Iron Curtain: Macrophages at the Interface of Systemic and Microenvironmental Iron Metabolism and Immune Response in Cancer"},{"label":"URL","value":"https://www.frontiersin.org/journals/immunology/articles/10.3389/fimmu.2021.614294/full"},{"label":"Date","value":"April 27, 2021"},{"label":"Justification (\"Paywalled\", \"OA\", \"Other (justify)\")","value":"OA"},{"label":"RBK Item","value":"- Cancer cells upregulate the expression of transferrin receptor (TFRC), a protein involved in iron uptake, and ferritin, a protein involved in cellular iron storage. In GBM, both transferrin receptor and ferritin are necessary for tumorigenesis."},{"label":"Title","value":"Preferential Iron Trafficking Characterizes Glioblastoma Stem-like Cells"},{"label":"URL","value":"https://www.cell.com/cancer-cell/fulltext/S1535-6108(15)00333-5?_returnURL=https%3A%2F%2Flinkinghub.elsevier.com%2Fretrieve%2Fpii%2FS1535610815003335%3Fshowall%3Dtrue"},{"label":"Date","value":"October 12, 2015"},{"label":"Justification (\"Paywalled\", \"OA\", \"Other (justify)\")","value":"OA"},{"label":"RBK Item","value":"- Due to the high iron levels in cancer cells, they are susceptible to ferroptosis, an iron-mediated form of cell death."},{"label":"Title","value":"Ferroptosis: mechanisms, biology and role in disease"},{"label":"URL","value":"https://www.nature.com/articles/s41580-020-00324-8"},{"label":"Date","value":"January 25, 2021"},{"label":"Justification (\"Paywalled\", \"OA\", \"Other (justify)\")","value":"Paywalled"},{"label":"RBK Item","value":"- Protein-bound ferric iron (Fe3+, stored within ferritin) is not directly involved in ferroptosis. As a result, ferritin can act as a ferroptosis suppressor by quenching available Fe2+ in the labile iron pool."},{"label":"Title","value":"Hepcidin Alleviates LPS-Induced ARDS by Regulating the Ferritin-Mediated Suppression of Ferroptosis"},{"label":"URL","value":"https://journals.lww.com/shockjournal/fulltext/2022/06000/hepcidin_alleviates_lps_induced_ards_by_regulating.13.aspx"},{"label":"Date","value":"June, 2022"},{"label":"Justification (\"Paywalled\", \"OA\", \"Other (justify)\")","value":"OA"},{"label":"RBK Item","value":"- GBM is a sexually dimorphic disease, with sexually dimorphic features in incidence, phenotype, response to therapy, and overall outcome. GBM is more frequent and aggressive in male patients. "},{"label":"Title","value":"Sex-Specific Differences in Glioblastoma"},{"label":"URL","value":"https://www.mdpi.com/2073-4409/10/7/1783"},{"label":"Date","value":"July 14, 2021"},{"label":"Justification (\"Paywalled\", \"OA\", \"Other (justify)\")","value":"OA"},{"label":"RBK Item","value":"- Sex difference in iron metabolism is thought to be a major contributor to the sexually dimorphic nature of GBM."},{"label":"Title","value":"Sexually dimorphic impact of the iron-regulating gene, HFE, on survival in glioblastoma"},{"label":"URL","value":"https://academic.oup.com/noa/article/2/1/vdaa001/5696853?login=false"},{"label":"Date","value":"February 17, 2020"},{"label":"Justification (\"Paywalled\", \"OA\", \"Other (justify)\")","value":"OA"}]
|
Physics
|
Physics
|
Free-Format Question
|
Single photon γ-ray imaging with high energy and spatial resolution perovskite semiconductor for nuclear medicine
|
https://www.nature.com/articles/s41467-025-63400-7
|
August 30, 2025
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Researchers present a pioneering approach relating to single-photon emission computed tomography (SPECT) that involves developing high resolution perovskite CsPbBr3 semiconductor detectors with different pixel and pitch sizes (Device E: 1.0 x 1.0 mm2 and 1.2mm; Device I: 1.5 x 1.5 mm2 and 1.6 mm), detector dimensions (Device E: 7.0 × 7.0 × 3.6 mm3; Device I: 8.0 × 8.0 × 5.6 mm3), and a pixelated configuration (4 x 4 pixels) capable of imaging single gamma-ray photons to aid in nuclear medicine applications. The gamma-ray camera consists of a tungsten collimator (4.5 mm thick, 3.5 mm deep holes, 0.5 mm wide, 6.0 mm long), a perovskite CsPbBr3 pixelated detector (CsPbBr3 crystal ingot diameter: 30mm, fabricated with Au and EGaIn contact combinations) and a 17-channel signal readout system (model 572A, dual 16 K input multichannel analyzer; gain of 0.8 x 100; shaping time 10 μs) for characterization analysis. The functional mechanism involves the gamma-ray photons emitted from the decay of 99mTc (gamma-ray decay with single energy of 141 keV; half-life period of 6.02 h) in a Na99Tc04 solution (sealed quartz capillary tubes with 0.5mm inner diameter, 1.0 mm external diameter) being captured and converted into electrical signals by the pixelated detectors after being passed through the collimator. The success is then characterized by the energy resolution (ER), the sensitivity, and the spatial resolution of gamma-ray images. A positive bias voltage of up to 700 V is applied to the bottom EGaIn electrode, while all the Au contacts are grounded.
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- Energy resolution (ER) of 99mTc through the pixelated CsPbBr3 detector for Devices E and I.
- Energy spectrum of pixelated CsPbBr3 detector under 99mTc gamma-ray source (keV/Counts) for each device (E, I).
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High resolution perovskite CsPbBr3 semiconductor detectors combined with collimators and gamma-ray sources are implemented to detect gamma-ray single-photons to aid in applications surrounding nuclear medicine. Performing patterned gamma-ray single-photon imaging using collimated aqueous solution Na99mTcO4 sources, the energy resolving capability for 99mTc gamma-rays at 141 keV of 16 pixels was tested for two different pixel and pitch configurations-Devices E and I. What is the predicted difference, if any, in the resulting energy resolutions (ERs) between Device E, Device I?
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Device E performs better than Device I by exhibiting a lower, sharp distribution of ERs in the range of 2-3% while Device I displays a higher overall ER of 3.5%.
|
- Single-photon emission computed tomography (SPECT) is an imaging technique that determines three-dimensional concentrations of radiopharmaceuticals int the body by measuring emitted gamma rays.
- Perovskite semiconductors are semiconductors that combine exceptional optoelectronic properties with versatile chemistry and simple synthesis.
- Energy Resolution is a metric that dominates the radionuclide identification and scatter rejection in γ-ray imaging.
|
[{"label":"RBK Item","value":"Single-photon emission computed tomography (SPECT) is an imaging technique that determines three-dimensional concentrations of radiopharmaceuticals int the body by measuring emitted gamma rays."},{"label":"Title","value":"Radioactive Transition Metals for Imaging and Therapy"},{"label":"URL","value":"https://pubs.acs.org/doi/10.1021/acs.chemrev.8b00281"},{"label":"Date","value":"October 9, 2018"},{"label":"Justification (\"Paywalled\", \"OA\", \"Other (justify)\")","value":"Paywalled (Referenced by original paper)"},{"label":"RBK Item","value":"Perovskite semiconductors are semiconductors that combine exceptional optoelectronic properties with versatile chemistry and simple synthesis."},{"label":"Title","value":"Detecting ionizing radiation using halide perovskite semiconductors processed through solution and alternative methods"},{"label":"URL","value":"https://www.nature.com/articles/s41566-021-00909-5"},{"label":"Date","value":"December 23, 2021"},{"label":"Justification (\"Paywalled\", \"OA\", \"Other (justify)\")","value":"Paywalled (Referenced by original paper)"},{"label":"RBK Item","value":"Energy Resolution is a metric that dominates the radionuclide identification and scatter rejection in γ-ray imaging."},{"label":"Title","value":"Energy resolution and linearity of XENON1T in the MeV energy range"},{"label":"URL","value":"https://link.springer.com/article/10.1140/epjc/s10052-020-8284-0"},{"label":"Date","value":"August 27, 2020"},{"label":"Justification (\"Paywalled\", \"OA\", \"Other (justify)\")","value":"OA"}]
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Physics
|
Physics/sensors
|
Numerical Values
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Flexible Stretchable Strain Sensor Based on LIG/PDMS for Real-Time Health Monitoring of Test Pilots
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https://www.mdpi.com/1424-8220/25/9/2884
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May 2, 2025
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Researchers tested the performance of a Laser-induced Graphene (LIG) strain sensor transferred onto a polydimethylsiloxane (PDMS). The sensor was prepared as follows: Initially, a 125 µm-thick PolyImide (PI) film was adhered to a metal substrate. Subsequently, the PI film was subjected to a line sweeping using a CO2 infrared laser scribing. The laser parameters were set as follows: Power of 2.3 W, scanning speed of 100 mm/s, and line width of 200 µm. This procedure generated striped patterns, ultimately forming 10 mm x 10 mm graphene blocks. The resulting graphene exhibited a porous structure and was primarily single-layered. The PI film with Graphene was then cut to match a Teflon mold with dimensions of 50 mm x 30 mm x 500 µm and positioned inside it, ensuring that the graphene stripes were aligned parallel to the 50 mm sides of the mold.
SYLGARD 184 silicone elastomer was mixed with its crosslinker at a ratio of 10:1 and homogenized using a blender for 5 min to prepare a PDMS solution. The solution was subsequently degassed in a vacuum dryer for 2 h to eliminate bubbles introduced during stirring. The PDMS solution was then carefully poured into the mold, ensuring uniformity of the mold to maintain consistent sensor thickness. The mold was cured in a vacuum drying oven at 80 °C for 2 h. On the following day, after complete curing, the upper layer of PDMS was carefully peeled off. Conductive silver paste was applied to both sides of the graphene, and electrical wires were connected. The sensor was then again placed inside the Teflon mold, in order to mold the other side of the sensor using the exact same procedure used for the first side of the sensor, and thereby completing the full encapsulation of the sensor.
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- Mechanical strain: Relative change in sensor length
- Electrical resistance: Measured in ohms
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The sensor was characterized in a tensile tester for mechanical strains up to 40%. The sensitivity of the sensor in form the gauge factor (GF) was calculated as a function of the strain. The GF is calculated as the relative change in electrical resistance divided by the strain.
What was the GF for the sensor in the range of 1% to 21% strain?
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GF = [18.6 - 22.8]
Note: No CI/SE/SD reported -> a ±10% fallback was applied using the value reported in the paper, 20.7
|
- Laser-Induced Graphene (LIG) is a method of creating graphene layers on top of common substrates like PI, PET or PDMS. Under laser Irradiation, chemical bonds are cleaved, releasing nitrogen and oxygen elements in gaseous forms, while the remaining carbon atoms rearrange to form LIG.
|
[{"label":"RBK Item","value":"Laser-Induced Graphene (LIG) is a method of creating graphene layers on top of common substrates like PI, PET or PDMS. Under laser Irradiation, chemical bonds are cleaved, releasing nitrogen and oxygen elements in gaseous forms, while the remaining carbon atoms rearrange to form LIG."},{"label":"Title","value":"Three-Dimensional (3D) Laser-Induced Graphene: Structure, Properties, and Application to Chemical Sensing"},{"label":"URL","value":"https://pmc.ncbi.nlm.nih.gov/articles/PMC8289247/"},{"label":"Date","value":"June 21, 2021"},{"label":"Justification (\"Paywalled\", \"OA\", \"Other (justify)\")","value":"OA, cited as reference 31."}]
|
Physics
|
Atomic Physics
|
Numerical Values
|
Observation of spin singlet butterfly Rydberg molecules in an ultracold atomic Rb gas
|
https://arxiv.org/abs/2510.21620
|
Oct 24, 2025
|
Researchers prepared $^{87}$Rb atoms in a crossed dipole trap operating at λ = 1064 nm with a temperature of 40 µK, a diameter of 40 µm, and a peak density of $4 \times 10^{13} \, \text{cm}^{−3}$. Initially, the atoms were kept the F=1 ground state, and photoassociation in the molecular state was attempted by a three-photon excitation scheme ($^5$s$_{1/2}$ →$^5$p$_{3/2}$ →$^5$d$_{5/2}$ →$^{18}$f$_{7/2}$) at 780 nm, 776 nm and 1308 nm, where the first two lasers were blue detuned to the intermediate states. After excitation, a CO$_2$ laser was implemented to ionize Rydberg atoms, and a reaction microscope was used to detect the ions. The experimental sequence consisted of 1100 excitation and ionization pulses with a duration of 3 µs. During excitation, the dipole trap was turned off to avoid ionization from the $^5$d$_{5/2}$ state. The electric field was switched off during photoassociation with a residual field of ~1 mV/cm. Later, the pulse duration was reduced to 1 µs, and the time of ionization was varied.
|
- Lifetime of the vibrational ground and first excited states of the butterfly molecules of $^{87}$Rb at a pulse duration of 1 µs during 1100 excitation and ionization pulses, by counting only the Rb$^{+}$ ions with zero momentum.
- Lifetime of the atomic resonance state (n=18) of $^{87}$Rb at a pulse duration of 1 µs during 1100 excitation and ionization pulses, by counting only the Rb$^{+}$ ions with zero momentum.
|
Researchers attempted a three-photon excitation scheme to photoassociate the n=18 singlet butterfly molecule of the Rubidium-87 element via the small f-state admixture in its electronic state. $^{87}$Rb is a butterfly long-range Rydberg molecule in the spin-singlet ($^1$P$_1$) configuration. With the intention of observing long-lived vibrational states within a well lying about 5GHz below the $^{18}$f$_{7/2}$ atomic resonance, they prepared $^{87}$Rb atoms in a crossed dipole trap operating at λ = 1064 nm with a temperature of 40 µK, a diameter of 40 µm, and a peak density of $4 \times 10^{13} \, \text{cm}^{−3}$. Atoms were kept initially in the F=1 ground state and photoassociation was attempted by means of.a three-photon excitation scheme ($^5$s$_{1/2}$ →$^5$p$_{3/2}$ →$^5$d$_{5/2}$ →$^{18}$f$_{7/2}$) at 780 nm, 776 nm and 1308 nm, where the first two lasers were blue detuned to the intermediate states. After excitation, a CO$_2$ laser was implemented to ionize Rydberg atoms, and a reaction microscope was used to detect the ions. The experimental sequence consisted of 1100 excitation and ionization pulses with a duration of 3 µs.
The lifetime of the atomic resonance state (n=18) and the vibrational ground and first excited states of the butterfly molecules of $^{87}$Rb at a pulse duration of 1 µs during 1100 excitation and ionization pulses were measured by counting only the Rb$^{+}$ ions with zero momentum. What is the absolute value in µs of difference in lifetime between the vibrational ground state and the atomic resonance state of $^{87}$Rb?
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|Δτ| = [1.43-2.89] µs, derived from the lifetimes of the vibrational ground state $\tau_{v=0}$ = (6.31±0.67) µs and the atomic resonance state of $^{87}$Rb $\tau_{18f_{7/2}}$ = (4.15±0.06) µs.
Note: CI/SE/SD reported for individual lifetimes in Fig. 4. -> Absolute error in lifetime measurement was calculated as (0.67+0.06) µs = 0.73 µs.
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- Ultralong-range Rydberg molecules (ULRMs) with high-ℓ character have highly asymmetric electronic states.
- The $^1$P$_1$ scattering produces the oscillating “stairwell” potential highlighted in black as well as the non-oscillating potential slicing through the stairwell.
|
[{"label":"RBK Item","value":"Ultralong-range Rydberg molecules (ULRMs) with high-ℓ character have highly asymmetric electronic states."},{"label":"Title","value":"Exploring the vibrational series of pure trilobite Rydberg molecules"},{"label":"URL","value":"https://www.nature.com/articles/s41467-023-43818-7"},{"label":"Date","value":"Dec 7, 2023"},{"label":"Justification (\"Paywalled\", \"OA\", \"Other (justify)\")","value":"OA"},{"label":"RBK Item","value":"The $^1$P$_1$ scattering produces the oscillating “stairwell” potential highlighted in black as well as the non-oscillating potential slicing through the stairwell."},{"label":"Title","value":"Approximate symmetries of long-range Rydberg molecules including spin effects"},{"label":"URL","value":"https://journals.aps.org/prresearch/abstract/10.1103/PhysRevResearch.6.013173"},{"label":"Date","value":"Feb 16, 2024"},{"label":"Justification (\"Paywalled\", \"OA\", \"Other (justify)\")","value":"OA"}]
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Physics
|
Physics / Fluid dynamics
|
MCQ
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Erosion induced by a disk translating toward or away from a granular bed
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https://arxiv.org/abs/2510.26980
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October 30, 2025
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Researchers were measuring the onset of erosion when a rigid circular disk is subjected to a single vertical stroke through quiescent water above a granular bed. The experiments were performed in a square glass tank (side 40 cm and height 60 cm) with the water level set to 40 cm. A transparent acrylic lid was placed a few millimeters beneath the free surface to suppress surface waves. At the bottom, a 1 cm thick, horizontally leveled bed of glass beads (mean diameter: 250 +/- 50 micrometers, density 2500 kg/m^3) was prepared. Before each erosion experiment, the surface was smoothed with a straight edge. A circular rigid PVC disk with thickness 2 mm was attached to a vertical shaft (1 cm diameter). The diameters D of the PVC disks used were in the range 5 cm ⩽ D ⩽ 15 cm. The vertical shaft was driven by an AC servomotor. An eccentric cam converts the continuous rotation of the motor into a sinusoidal translation of the vertical shaft. The stroke length L has been varied in the range 2 cm ⩽ L ⩽ 5.2 cm. The minimum distance b between the disk and the granular bed was varied in the range 0.2 cm ⩽ b ⩽ 2 cm.
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- The minimum distance b between the disk and the granular bed.
- The radius a_1 of the starting vortex at the moment when the disk completes its stroke.
- The local velocity induced by the impact of the starting vortex ring.
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Researchers were measuring the onset of erosion when a rigid circular disk is subjected to a single vertical stroke through quiescent water above a granular bed.
The critical Shields number Sh^c_CV was defined using the local velocity u_CV induced by the impact of the starting vortex ring as a function of b/a_1, where b is the minimum distance between the disk and the granular bed and a_1 is the radius of the starting vortex at the moment when the disk completes its stroke.
What stroke length produced the largest increase of Sh^c_CV relative to b/a_1 for a disk of diameter D=10 cm and b ranging from 0.2 to 2.0 cm?
A. 2.0 cm.
B. 3.6 cm.
C. 4.4 cm.
D. 5.2 cm.
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A. 2.0 cm.
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- The critical Shields number, Sh_c, describes the ratio of the drag force of the fluid to the apparent weight of the particles.
|
[{"label":"RBK Item","value":"The critical Shields number, Sh_c, describes the ratio of the drag force of the fluid to the apparent weight of the particles. "},{"label":"Title","value":"Application of similarity principles and turbulence research to bed-load movement."},{"label":"URL","value":"https://scispace.com/pdf/application-of-similarity-principles-and-turbulence-research-jatjbrj9wh.pdf"},{"label":"Date","value":"1936"},{"label":"Justification (\"Paywalled\", \"OA\", \"Other (justify)\")","value":"OA. Cited in paper."}]
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Physics
|
Plasma Physics
|
Free-Format Question
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Experimental validation of electron correlation models in warm dense matter
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https://arxiv.org/abs/2509.10107
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September 12, 2025
|
Shock-compressed aluminium foils (50 micron thickness) were generated at the European XFEL using 8 ns, 26J, 515 nm Dipole 100-X laser pulses. The samples (rho= 4 g cm^(-3), T approximately 0.6 eV) were probed by 8.307 keV self-seeded XFEL pulses to record inelastic X-ray Thomson-scattering (XRTS) spectra at momentum transfers k= 0.99 - 2.57 A^(-1). Each spectrum averaged approximately 40 shots per geometry.
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- XRTS spectra showing plasmon peak energy and width as a function of k (units inverse Angstrom).
- Qualitative change of plasmon feature shape (broadening, asymmetry).
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X-Ray Thomson scattering measurements are conducted for 50-μm thick, shock-compressed aluminium foils at a temperature of ~0.6 eV. When the momentum transfer increases from k = 0.99 A^(-1) to 2.57 A^(-1) in shock-compressed aluminium, how does the plasmon feature change in the XRTS spectra?
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The plasmon peak shifts to higher energy loss and broadens, becoming weaker and more asymmetric.
|
- Plasmons are collective electron oscillations observed as an inelastic scattering-peak.
-Inelastic X-ray Thomson-scattering is a experimental technique involving probing a sample with a high-energy X-rays and recording the photons that shifted in energy after scattering off weakly-bound electrons.
|
[{"label":"RBK Item","value":"-Inelastic X-ray Thomson-scattering is a experimental technique involving probing a sample with a high-energy X-rays and recording the photons that shifted in energy after scattering off weakly-bound electrons."},{"label":"Title","value":"X-ray Thomson scattering in high energy density plasmas"},{"label":"URL","value":"https://journals.aps.org/rmp/abstract/10.1103/RevModPhys.81.1625"},{"label":"Date","value":"December 1, 2009"},{"label":"Justification (\"Paywalled\", \"OA\", \"Other (justify)\")","value":"Paywalled source is the canonical reference for this RBK item; couldn't find OA version"}]
|
Physics
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Quantum Technology, Superconducting Qubits
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Numerical Values
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Spin environment of a superconducting qubit in high magnetic fields
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https://www.nature.com/articles/s41467-025-65528-y
|
Oct 29, 2025
|
The gradiometric granular aluminum (grAl) is fabricated on a double-sided polished c-plane sapphire substrate using lift-off electron-beam lithography. A single resist layer of PMMA A4, coated with an 8 nm aluminum anti-static layer, is patterned with a 100 keV electron-beam writer. After patterning, the anti-static layer is removed using MF319 developer, which contains tetramethylammonium hydroxide, followed by development of the PMMA resist in a 6 °C isopropyl alcohol (IPA)/H2O solution (1:3 volume ratio). Before metal deposition, the substrate undergoes a 15s Ar/O2 plasma cleaning process using a Kaufman ion source. A 20 nm grAl layer is then deposited in a single evaporation step at room temperature, using an oxygen atmosphere at a chamber pressure of approximately 1 × 10^-4 mbar and a deposition rate of approximately 1 nm/s. A titanium gettering step is performed beforehand to enhance the vacuum quality to ~1 × 10−8 mbar before evaporation. During the lift-off process, the sample is sequentially submerged in an acetone bath, a 30-minute N-ethyl-2-pyrrolidone bath with ultrasonic cleaning, and then in an ethanol bath. After that, the researcher galvanically coupled a 1mm long stripline readout resonator to the qubit circuit, which consisted of a superinductor, a geometric finger capacitance, and a graphene nanojunction. Implemented by a ~(20 nm)3 grAl volume, the nanojunction offers a sinusoidal current-phase relation similar to a conventional Al/AlOx/Al Josephson Junction, while exposing a minute cross-section to Fraunhofer interference. Then, implement a gradiometric design with two flux loops, and subsequently perform two-tone (TT) spectroscopy at half flux bias in zero field at 150 mK.
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- Qubit Frequency (fq) of gradiometric granular aluminum (grAl) nanojunction fluxonium qubit at half flux bias in zero field at 150 mK.
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A gradiometric granular aluminum (grAl) nanojunction fluxonium qubit is made out of gradiometric granular aluminum (grAl), which is fabricated on a double-sided polished c-plane sapphire substrate. Then, a single resist layer of PMMA A4 was coated with an 8 nm aluminum anti-static layer. After patterning, the anti-static layer is removed, followed by development of the PMMA resist in a 6 °C isopropyl alcohol (IPA)/H2O solution (1:3 volume ratio). A 20 nm grAl layer is then deposited in a single evaporation step at room temperature, using an oxygen atmosphere at a chamber pressure of approximately 1 × 10^-4 mbar and a deposition rate of approximately 1 nm/s. During the lift-off process, the sample is sequentially submerged in an acetone bath, a 30-minute N-ethyl-2-pyrrolidone bath with ultrasonic cleaning, and then in an ethanol bath. After that, the galvanically coupled a 1mm long stripline readout resonator to the qubit circuit, which consisted of a superinductor, a geometric finger capacitance, and a graphene nanojunction. Implemented by a ~(20 nm)3 grAl volume, the nanojunction offers a sinusoidal current-phase relation similar to a conventional Al/AlOx/Al Josephson Junction, while exposing a minute cross-section. Josephson energy (EJ/h) of gradiometric granular aluminum (grAl) nanojunction fluxonium qubit is 32.2 GHz, and other parameters such as Critical current of the nanojunction (Ic) is 64.9 nA, Charging energy (Ec / h) is 14.1 GHz, Capacitance: $ C = 1.37 $ fF, inductive energy E_L / h = 0.454 GHz, and Superinductor inductance is Lq = 360 nH. Now it is maintained at a temperature of 150 mK and has performed two-tone (TT) spectroscopy at half flux bias in zero field. What is the estimated qubit frequency (fq) in GHz?
|
Qubit Frequency (fq) of gradiometric granular aluminum (grAl) nanojunction fluxonium qubit at half flux bias in zero field is 2.13 - 2.60 GHz.
Note: No CI/SE/SD reported -> ±10% fallback applied to 2.365 GHz.
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- The reduction of the superconducting gap can be mitigated by using field-resilient, low-loss superconductors like granular aluminum (grAl).
- The grAl nanojunction fluxonium qubit, known as gralmonium, combines the grAl field resilience with the unique benefits of the grAl nanojunction, offering low microwave losses and a compact nanoscopic footprint.
- The critical current fluctuations are inconsistent with transverse coupling to a fixed frequency TLS, but originate from fluctuations of the nanojunction energy. This issue is also relevant for standard Al/AlOx/Al tunnel JJs.
|
[{"label":"RBK Item","value":"The reduction of the superconducting gap can be mitigated by using field-resilient, low-loss superconductors like granular aluminum (grAl)."},{"label":"Title","value":"Superconducting granular aluminum resonators resilient to magnetic fields up to 1 Tesla"},{"label":"URL","value":"https://pubs.aip.org/aip/apl/article-abstract/117/12/120502/1061305/Superconducting-granular-aluminum-resonators?redirectedFrom=fulltext"},{"label":"Date","value":"Sep 25, 2020"},{"label":"Justification (\"Paywalled\", \"OA\", \"Other (justify)\")","value":"Paywalled, but this is cited as reference 39 in the paper"},{"label":"RBK Item","value":"The grAl nanojunction fluxonium qubit, known as gralmonium, combines the grAl field resilience with the unique benefits of the grAl nanojunction, offering low microwave losses and a compact nanoscopic footprint that eliminates Fraunhofer interference."},{"label":"Title","value":"Granular aluminium nanojunction fluxonium qubit"},{"label":"URL","value":"https://www.nature.com/articles/s41563-022-01417-9"},{"label":"Date","value":"Dec 8, 2022"},{"label":"Justification (\"Paywalled\", \"OA\", \"Other (justify)\")","value":"Paywalled, but this is cited as reference 46 in the paper"},{"label":"RBK Item","value":"The critical current fluctuations are inconsistent with transverse coupling to a fixed frequency TLS, but originate from fluctuations of the nanojunction energy, potentially arising from structural defects, charge noise, or paramagnetic impurities. This issue is also relevant for standard Al/AlOx/Al tunnel JJs."},{"label":"Title","value":"Low frequency resistance and critical current fluctuations in Al-based Josephson junctions"},{"label":"URL","value":"https://pubs.aip.org/aip/apl/article-abstract/102/14/142602/125186/Low-frequency-resistance-and-critical-current?redirectedFrom=fulltext"},{"label":"Date","value":"April 9, 2013"},{"label":"Justification (\"Paywalled\", \"OA\", \"Other (justify)\")","value":"Paywalled, but this is cited as reference 30 in the paper"}]
|
Biology
|
Regenerative Medicine, Microgravity Research
|
Free-Format Question
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Microgravity-driven Rab27B activation amplifies mesenchymal stem cell-derived extracellular vesicle production and functions
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https://stemcellres.biomedcentral.com/articles/10.1186/s13287-025-04711-w
|
October 29, 2025
|
Human umbilical cord-derived mesenchymal stem cells (UCMSCs) were isolated from fresh umbilical cords. These were cut into pieces, treated with collagenase type I (Sigma, GER), and incubated in Minimum Essential Medium α (α-MEM; Gibco, USA) supplemented with 10% fetal bovine serum (FBS; Procell, CHN). Cells were passaged at 90% confluence, and all experiments were performed using cells between passages 3 and 6.
To imitate microgravity (μg) conditions, UCMSCs were cultured in a three-dimensional Rotary Cell Culture System (RCCS; RCCS-4SQ, Synthecon, US) at 27 rpm. UCMSCs of the same cell line were seeded in both conventional flasks and RCCS culture vessels at 10^6 cells/ml in exosome-free medium.
Supernatants containing bench-control and microgravity-derived extracellular vesicles (EVs) (g-EVs and μg-EVs) were harvested every 48 hours. These were centrifuged at 300 × g for 10 min at 4 °C to remove residual cells, further centrifuged at 3,000 × g for 10 min at 4 °C to isolate dead cells, and centrifuged once more at 10, 000 × g for 30 min at 4 °C to remove cell debris. Finally, the remaining supernatants were ultracentrifuged at 120 000 × g for 70 min at 4 °C (Beckman Coulter, USA) to obtain EVs. These were preserved in PBS and stored at -80 °C.
EV diameter and concentration were measured by nanoparticle tracking analysis (NTA) using a NanoSight NS300 instrument (Malvern, UK) equipped with a red laser and an sCMOS camera. 30-second triplicate measurements were performed with NTA software version 3.4 Build 3.4.4, using a camera gain of 55.
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- Yield (x10¹¹ particles/ml) of microgravity-derived extracellular vesicles (g-EVs; μg-EVs)
- Extracellular vesicles diameter (nm) of microgravity-derived extracellular vesicles (g-EVs; μg-EVs)
- Extracellular vesicles concentration (particles/ml) of microgravity-derived extracellular vesicles (g-EVs; μg-EVs)
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Human umbilical cord-derived mesenchymal stem cells (UCMSCs) were used to evaluate the therapeutic potential of extracellular vesicles (EVs) derived from mesenchymal stem cells (MSCs). UCMSCs were isolated from fresh umbilical cords, treated with collagenase type I, incubated in Minimum Essential Medium α supplemented with 10% fetal bovine serum, and passaged at 90% confluence. A total of 10⁶ cells/mL from passages 3 and 6 were cultured in a three-dimensional Rotary Cell Culture System (RCCS) at 27 rpm under both conventional and simulated microgravity conditions, using exosome-free medium. Supernatants containing bench-control and microgravity-derived extracellular vesicles (g-EVs and μg-EVs, respectively) were collected every 48 hours and centrifuged for 10 min at 4 °C to remove residual cells (300 × g), isolate dead cells (3,000 × g), and eliminate cell debris (10,000 × g, 30 min). Supernatants were ultracentrifugated (120,000 x g, 70 min. at 4° C) to obtain EVs. EV diameter and concentration were measured by nanoparticle tracking analysis (NTA) using a NanoSight NS300 instrument. Triplicate 30-second measurements were performed with NTA software. How would you expect the levels of the particle diameter (nm) in the μg-EV group to differ from that of the g-EV group?
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The particle diameter (nm) in the μg-EV group would be higher than that in the g-EV group.
|
- Mesenchymal stem cells (MSCs) are widely used in regenerative medicine due to their immunomodulatory properties and tissue repair capabilities
- The therapeutic effects of MSCs are primarily mediated through paracrine secretion of bioactive molecules rather than direct cell differentiation
- Extracellular vesicles (EVs) derived from MSCs (MSC-EVs) have emerged as key mediators of these paracrine functions, mimicking the therapeutic potential of parental cells
- Despite their potential, the clinical translation of MSC-EVs faces a major challenge due to the low production yields of conventional two-dimensional (2D) monolayer cultures
|
[{"label":"RBK Item","value":"Mesenchymal stem cells (MSCs) are widely used in regenerative medicine due to their immunomodulatory properties and tissue repair capabilities"},{"label":"Title","value":"Clinical application of mesenchymal stem cell in regenerative medicine: a narrative review"},{"label":"URL","value":"https://link.springer.com/article/10.1186/s13287-022-03054-0"},{"label":"Date","value":"July 28, 2022"},{"label":"Justification (\"Paywalled\", \"OA\", \"Other (justify)\")","value":"OA"},{"label":"RBK Item","value":"The therapeutic effects of MSCs are primarily mediated through paracrine secretion of bioactive molecules rather than direct cell differentiation"},{"label":"Title","value":"Therapeutic Properties of Mesenchymal Stromal/Stem Cells: The Need of Cell Priming for Cell-Free Therapies in Regenerative Medicine"},{"label":"URL","value":"https://www.mdpi.com/1422-0067/22/2/763"},{"label":"Date","value":"January 14, 2021"},{"label":"Justification (\"Paywalled\", \"OA\", \"Other (justify)\")","value":"OA"},{"label":"RBK Item","value":"Extracellular vesicles (EVs) derived from MSCs (MSC-EVs) have emerged as key mediators of these paracrine functions, mimicking the therapeutic potential of parental cells"},{"label":"Title","value":"Immune Cell-Derived Extracellular Vesicles – Functions and Therapeutic Applications"},{"label":"URL","value":"https://www.cell.com/trends/molecular-medicine/abstract/S1471-4914(19)30035-8?_returnURL=https%3A%2F%2Flinkinghub.elsevier.com%2Fretrieve%2Fpii%2FS1471491419300358%3Fshowall%3Dtrue"},{"label":"Date","value":"May, 2019"},{"label":"Justification (\"Paywalled\", \"OA\", \"Other (justify)\")","value":"Paywalled"},{"label":"RBK Item","value":"Despite their potential, the clinical translation of MSC-EVs faces a major challenge due to the low production yields of conventional two-dimensional (2D) monolayer cultures"},{"label":"Title","value":"Emerging innovations on exosome-based onco-therapeutics"},{"label":"URL","value":"https://www.frontiersin.org/journals/immunology/articles/10.3389/fimmu.2022.865245/full"},{"label":"Date","value":"August 31, 2022"},{"label":"Justification (\"Paywalled\", \"OA\", \"Other (justify)\")","value":"OA"}]
|
Chemistry
|
Materials Chemistry/ Analytical Chemistry
|
Numerical Values
|
Synthesis and characterization of gold-coated nanodiamonds through green chemistry as potential radiosensitizers for proton therapy
|
https://arxiv.org/pdf/2504.11061
|
April 15, 2025
|
Commercially available nanodiamonds (ND), with a size of 50 nm (MSY 0-0.1), were subjected to thermal treatments. They were annealed at 800°C for 2 h in a N2 atmosphere, resulting in the sample labeled Ann 50 nm ND. Subsequently, a portion of the annealed nanodiamonds underwent oxidation at 500°C for 12 hours in air, forming sample Ox 50 nm ND. The obtained ND were gold-coated using root extracts from Nymphaea alba. 2g of powder root extract was dispersed in 120 mL of Milli-Q water, filtered twice, and used immediately to prevent any changes in its composition. The 27 mg NDs were dispersed in 25 mL of above prepared root extract solutions and subjected to ultrasonic irradiation for 10 min at room temperature, using an ultrasonic batch operating at 38 kHz and 100 W. This was followed by magnetic stirring for an additional 40 min. After stirring, a 25 mM HAuCl4 water solution (2mL) was introduced, causing the reaction mixture to immediately change color from bright yellow to brown. Then, a 0.1 M NaOH solution was added dropwise until the pH reached 8. At this point, a second volume of 25 mM HAuCl4 water solution (8mL) was gradually added while stirring at room temperature, leading to a color change from brown to gray-blue (Ox ND Au 50). The samples were incubated overnight at room temperature with continuous magnetic stirring, washed twice with Mili-Q water at 6000 RPM for 20 min, and then freeze-dried for 48 h. PXRD analysis was performed on the Ox ND Au 50 sample in the 2θ range from 10° to 100°.
|
* PXRD analysis, performed on the Ox ND Au 50 sample with a Bruker D2 Phaser diffractometer, equipped with a Cu Kα X-ray tube, in the 2θ range from 10° to 100°.
* Crystallite sizes of nanodiamonds, estimated using Scherrer’s equation based on the highest-intensity peaks of PXRD analysis.
|
Ox ND Au 50 sample was synthesized using commercially available ND. They were first annealed at 800°C and then underwent oxidation at 500°C for 12 hours in air. Their crystallite size was calculated using the Scherrer equation from PXRD analysis. What will be the crystallite size (nm) for Ox ND Au 50?
|
6.99 - 8.53 nm
|
* Nymphaea alba root extracts act as a green reducing agent for the in situ reduction of HAuCl₄ and stabilization of the nanoparticles.
* Nanodiamonds (ND) are particularly attractive for biomedical applications due to their biocompatibility, ease of functionalization, and ability to penetrate biological barriers.
* The PXRD patterns of the nanodiamonds (NDs) exhibit characteristic diffraction peaks, which can be indexed to the diamond crystal planes (111), (220), and (311).
|
[{"label":"RBK Item","value":"Nymphaea alba root extracts act as a green reducing agent for the in situ reduction of HAuCl₄ and stabilization of the nanoparticles."},{"label":"Title","value":"Sono-biosynthesis and characterization of aunps from danube delta nymphaea alba root extracts and their biological properties"},{"label":"URL","value":"https://www.mdpi.com/2079-4991/11/6/1562"},{"label":"Date","value":"June 14, 2021"},{"label":"Justification (\"Paywalled\", \"OA\", \"Other (justify)\")","value":"OA"},{"label":"RBK Item","value":"Nanodiamonds (ND) are particularly attractive for biomedical applications due to their biocompatibility, ease of functionalization, and ability to penetrate biological barriers. "},{"label":"Title","value":"The properties and applications of nanodiamonds"},{"label":"URL","value":"https://www.nature.com/articles/nnano.2011.209"},{"label":"Date","value":"December 18, 2011"},{"label":"Justification (\"Paywalled\", \"OA\", \"Other (justify)\")","value":"Paywalled"},{"label":"RBK Item","value":"The PXRD patterns of the nanodiamonds (NDs) exhibit characteristic diffraction peaks, which can be indexed to the diamond crystal planes (111), (220), and (311). "},{"label":"Title","value":"Characterization of diamond-like carbon films by SEM, XRD and Raman spectroscopy"},{"label":"URL","value":"https://www.sciencedirect.com/science/article/abs/pii/S0169433210005374?via%3Dihub"},{"label":"Date","value":"August 15, 2010"},{"label":"Justification (\"Paywalled\", \"OA\", \"Other (justify)\")","value":"Paywalled"}]
|
Biology
|
Nanoparticle vaccines/Animal models
|
Numerical Values
|
In vivo reprogramming of cytotoxic effector CD8+ T cells via fractalkine-conjugated mRNA-LNP
|
https://www.biorxiv.org/content/10.1101/2025.10.29.685358v1
|
October 30, 2025
|
C57BL/6 mice were infected intraperitoneally with 2x10⁵ plaque-forming units of a lymphocytic choriomeningitis virus (LCMV)-Armstrong to generate an acute infection model. Researchers generated mouse fractalkine-conjugated mRNA encoding LNP with a 1:0.75 μg mRNA/μg fractalkine ratio. Seven days after LCMV infection, mice were intravenously given 200uL PBS, 10ug of fractalkine-conjugated tdTomato mRNA-LNP in 200uL of PBS, or no treatment. The next day, peripheral blood mononuclear cells (PBMCs) were isolated from mice by collecting blood in a 4% sodium citrate solution and isolating using standard Histopaque-1083-based gradient centrifugation. Cells were washed with RPMI containing 1% fetal bovine serum before staining. Mice PBMCs were tested for tdTomato expression in peripheral blood GP33+ CX3CR1+ Teff cells and then mice received either another dose of 200uL PBS for the PBS group or 10ug of fractalkine-conjugated GFP mRNA-LNP in 200uL of PBS for the previous LNP and no treatment groups. 24 hours after the second infusion, PBMCs were isolated again and expression of tdTomato and GFP in GP33+ CX3CR1+ Teff cells were assessed using flow cytometry and expressed as a percentage of total GP33+ CX3CR1+ Teff cells. Flow cytometry was acquired on a Symphony A5 using Zombie Yellow Live Dead Stain, GP33 tetramer-PE, and BV605 Anti-Mouse CX3CR1 clone SA011F11. Data was analyzed using FlowJo software.
|
- Expression of tdTomato in CX3CR1+ Teff cells as a percentage of total GP33+ CX3CR1+ Teff cells after different treatments (PBS, fractalkine-conjugated tdTomato mRNA-LNP, and no treatment)
- Expression of GFP in tdTomato+ CX3CR1+ Teff cells as a percentage of total tdTomato+ GP33+ CX3CR1+ Teff cells after different treatments (PBS, fractalkine-conjugated tdTomato mRNA-LNP, and no treatment)
|
Two doses of 10ug mouse fractalkine-conjugated mRNA encoding LNP in 200uL of PBS are intravenously administered to previously intraperitoneally LCMV infected (2x10⁵ plaque forming units) C57BL/6 mice. The first LNP dose is administered 7 days after LCMV infection, and the second LNP dose the following day. PBMCs are isolated using 4% sodium citrate solution and isolated using standard Histopaque-1083-based gradient centrifugation and washed with RPMI + 1% FBS before staining. If flow cytometry is acquired on a Symphony A5 using Zombie Yellow Live Dead Stain, GP33 tetramer-PE, and BV605 Anti-Mouse CX3CR1 clone SA011F11 and data is analyzed using FlowJo software, what percentage of the tdTomato+ GP33+ CX3CR1+ Teff cells in the PBMCs will express GFP?
|
%tdTomatoGFP = [73 - 83] % derived from approximately 78% of tdTomato+ GP33+ CX3CR1+ Teff cells expressing GFP. Note: No CI/SE/SD reported -> fallback ±5 pp applied
|
-CX3CR1/fractalkine receptor is specific to the surface of Teff cells and is not present on other types of T cells.
-The cognate ligand for CX3CR1 is CX3CL1, which is also known as fractalkine.
|
[{"label":"RBK Item","value":"-CX3CR1/fractalkine receptor is specific to the surface of Teff cells and is not present on other types of T cells. "},{"label":"Title","value":"Functional classification of memory CD8 + T cells by CX3CR1 expression"},{"label":"URL","value":"https://www.nature.com/articles/ncomms9306"},{"label":"Date","value":"September 25, 2015"},{"label":"Justification (\"Paywalled\", \"OA\", \"Other (justify)\")","value":"OA"},{"label":"RBK Item","value":"-The cognate ligand for CX3CR1 is CX3CL1, which is also known as fractalkine. "},{"label":"Title","value":"Identification and molecular characterization of fractalkine receptor CX3CR1, which mediates both leukocyte migration and adhesion"},{"label":"URL","value":"https://pubmed.ncbi.nlm.nih.gov/9390561/"},{"label":"Date","value":"November 14, 1997"},{"label":"Justification (\"Paywalled\", \"OA\", \"Other (justify)\")","value":"OA"}]
|
Physics
|
Physics / Materials Science
|
MCQ
|
Advancing antiferromagnetic nitrides via metal alloy nitridation
|
https://www.nature.com/articles/s43246-025-00892-2
|
July 30, 2025
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Researchers synthesized Mn₁₋ₓGaₓN thin films in two steps. First, Mn₃Ga alloy films were deposited on (001)-oriented MgO substrates using pulsed laser deposition (PLD) from a stoichiometric Mn₃Ga target at 500 °C under a base pressure of 1 × 10⁻⁸ Torr. The films were then cooled and annealed via rapid thermal annealing (RTA) at 700 °C for 1 h under a pure ammonia atmosphere to form Mn₁₋ₓGaₓN thin films. X-ray linear dichroism (XLD) measurements were performed at the Mn L-edges using linearly polarized X-rays incident at 0° and 60° relative to the sample surface. The X-ray absoprtion spectra were recorded under out-of-plane magnetic fields of 0 T and 0.4 T at room temperature to probe field-induced changes in orbital occupancy. The XLD signal was computed as the difference between the intensities I₀° and I₆₀°.
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- X-ray absorption spectra (XAS) collected at Mn L-edges under linearly polarized light at two incidence angles, 0° and 60°, under out-of-plane magnetic fields of 0 T and 0.4 T.
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Mn₁₋ₓGaₓN thin films were prepared on (001)-oriented MgO substrates and annealed under ammonia to form Mn nitrides. X-ray linear dichroism (XLD) spectra were measured at Mn L-edges by recording X-ray absorption at 0° and 60° incidence angles, under applied magnetic fields of 0 T and 0.4 T, and calculating the intensity differences (I₀° - I₆₀°). Based on these conditions, which of the following best describes the change in the XLD signal upon applying a 0.4 T out-of-plane magnetic field for photon energies spanning 630 to 660 eV?
A. The peaks in the XLD spectrum increase and become narrower.
B. The integrated area of XLD spectra becomes smaller, with an overall positive value.
C. The XLD disappears entirely.
D. The XLD spectrum becomes predominantly negative.
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D. The XLD spectrum becomes predominantly negative.
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- The structural and magnetic properties of manganese-based nitride films are highly sensitive to nitrogen stoichiometry and can lead to the formation of secondary phases.
- Rapid thermal processing annealing is a critical step for facilitating nitrogen incorporation into the metallic lattice and promoting the formation of high-quality single-crystal films.
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[{"label":"RBK Item","value":"The structural and magnetic properties of manganese-based nitride films are highly sensitive to nitrogen stoichiometry and can lead to the formation of secondary phases."},{"label":"Title","value":"Observation of large exchange bias and topological Hall effect in manganese nitride films"},{"label":"URL","value":"https://doi.org/10.1063/1.5025147"},{"label":"Date","value":"March 27, 2018"},{"label":"Justification (\"Paywalled\", \"OA\", \"Other (justify)\")","value":"Paywalled, but cited a reference [14]. Its pre-published version can be found as OA in https://arxiv.org/abs/1708.02540."}]
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