bluuebunny/crossref_metadata_2025 huggingface dataset:
Multifunctional strain-activated liquid–metal composite films with electromechanical decoupling for stretchable electromagnetic shielding
Authors: Chen Jiali , Chen Xuezhe , Su Yaozhuo , Shen Bin , Zheng Wenge
Published: August 2024

Stretchable liquid metal composite films with strain-insensitive electromagnetic interference shielding performance are fabricated via scraping and pre-stretching. These films also have potential applications in Joule heating and motion monitoring.
Epitaxial strain manipulation of the cluster glass state in LaMnO3 films
Authors: Liang Yongmei , Lian Haonan , Li Yaqiang , Liu Dan , Han Baochen , Qi Jian , Ma Dongxiao
Published: August 2024

This study creatively demonstrates the control of the cluster glass state in a single-layer film by manipulating the strain state of the LMO films.
A 3D photoluminescent Eu(iii)-MOF sensor supported by a tetracarboxylate ligand for the sensitive and selective detection of Cd2+ and o-nitrophenol
Authors: Sen Charanjeet , Devi Swaita , Niharika  , Bhagat Nidhi , Sheikh Haq Nawaz
Published: August 2024

A novel 3D luminescent metal–organic framework (MOF) denoted as [Eu(BTA)0.5(H2BTA)0.5(H2O)]n (Cj-2) has been constructed from a π-conjugated ligand with a tetracarboxylate group, 1,2,4,5-benzenetetracarboxylic acid (BTA), via solvothermal synthesis.
Effect of fuel dosage in self-propagation combustion: evolution of BiOCl to BiOCl/Bi24O31Cl10 heterojunctions enriched with oxygen vacancies
Authors: Liu Han , Zhang Wenjun , Chen Meng
Published: August 2024

BiOCl/Bi24O31Cl10 heterojunction: BiOCl and Bi24O31Cl10 contact to form a type-Z heterojunction. The band bending facilitates the transfer and recombination of charge carriers of low redox potential, leading to improved degradation efficiency.
A novel hydroxynaphthalimide-derived regenerative fluorescent probe for the detection of formaldehyde in cells and zebrafish
Authors: Wang Yao , Li Wenzhai , Wang Kun , Rong Xiaodi , Liu Xueting , Yan Tingyi , Cai Xinyu , Liu Caiyun , Sheng Wenlong , Zhu Baocun
Published: August 2024

A novel hydroxynaphthalimide-derived regenerative fluorescent probe was developed to monitor formaldehyde in cells and zebrafish.
Palladium-catalysed directed remote meta-C–H functionalization of arenes using a cyclopentenyl-pyridyl template
Authors: Huang Jun , Tang Jinghong , Yan Yifei , Liu Zelin , He Siquan , Jin Zhong
Published: August 2024

Highly meta-selective C–H olefination, deuteration and acetoxylation of benzyl alcohols were realized by applying a practical directing template featuring a non-aromatic cyclopentenyl-pyridine scaffold.
Harnessing triazole–oxadiazole–trinitromethyl moieties in the synthesis of insensitive energetic material with enhanced detonation performance
Authors: Vangara Srinivas , Kommu Nagarjuna , Sahoo Akhila K.
Published: August 2024

The nitrogen-and oxygen-rich azole-based high energetic compound 3,3′-(2-(trinitromethyl)-2H-1,2,3-triazole-4,5-diyl)-bis(1,2,4-oxadiazole) was synthesized from a readily accessible bis-cyano-substituted-azole in three steps with good yield.
Steric influence and controlled dynamic process in a chiral square planar nickel(ii) complex supported by a dipyrromethane-based NNNN tetradentate ligand
Authors: Guchhait Tapas , Giri Monalisa , Mishra Soumya , Roy Satabdi
Published: August 2024

The intra-ligand congestion in a square planar nickel(ii) complex of a dipyrromethane-based ligand decides helical chirality and the pair of enantiomers exists in a dynamic equilibrium in solution. A similar complex without congestion is achiral.
Encapsulation of 4-oxo-N-(4-hydroxyphenyl) retinamide in human serum albumin nanoparticles promotes EZH2 degradation in preclinical neuroblastoma models
Authors: Mrunalini Boddu , Dev Atul , Kushwaha Avinash Chandra , Sardoiwala Mohammed Nadim , Karmakar Surajit
Published: August 2024

Schematic represents 4O4HPR loaded HSANPs directing the proteasomal degradation of the polycomb group of the protein, EZH2, by triggering oxidative stress and PKC-δ activation, leading to the killing of neuroblastoma cancer cells.
The Relationship Between Poststroke Dysphagia and Poststroke Depression and Its Risk Factors
Authors: Horn Janet , Simpson Kit N. , Simpson Annie N. , Bonilha Leonardo F. , Bonilha Heather S.
Published: August 2024

Purpose:

A diagnosis of dysphagia and/or depression after stroke can impact the physical, psychological, and social welfare of stroke survivors. Although poststroke depression (PSD) and poststroke dysphagia are known to occur concurrently, there is a paucity of research that has specifically investigated their association. Therefore, we aimed to study the relationship between PSD and poststroke dysphagia during acute inpatient hospitalization and within 90 days after discharge. Furthermore, we aimed to evaluate the odds and hazard of being diagnosed with depression after stroke and estimate the time to depression diagnosis from the initial stroke diagnosis in patients with and without a diagnosis of dysphagia.

Method:

Using the acute inpatient hospital data set from our previous work, we pulled additional postdischarge administrative claims data from the 2017 Medicare 5% Limited Data Set and conducted a retrospective, cross-sectional study of patients diagnosed with poststroke dysphagia and PSD.

Results:

Patients diagnosed with poststroke dysphagia had 2.7 higher odds of being diagnosed with PSD and had an approximately 1.75-fold higher hazard for PSD diagnosis in the 90 days after discharge compared to patients not diagnosed with dysphagia. Risk factors for PSD included having dysphagia, being female, and having dual eligibility.

Conclusions:

Our results demonstrated a significant association between PSD and poststroke dysphagia. Additional research should further explore the impact of PSD on poststroke dysphagia.
The peculiar optical spectrum of Mrk 231
Authors: Misquitta Persis , Dünnebier Benita , Eckart Andreas , Bhat Harshitha
Published: August 2024

Markarian 231 (Mrk 231) is one of the closest and brightest ultra-luminous infrared galaxies that is considered to be in a late galaxy merger stage. The optical spectrum of Mrk 231 presents peculiar features and has been the subject of detailed studies. In this paper we study the optical long-slit spectroscopy of the central arcsecond of Mrk 231 as well as six off-nuclear spectral positions observed using the multi-object double spectrographs at the Large Binocular Telescope. Additionally, we carefully examine acquisition images taken before the spectroscopic observations. We find that both the nuclear and off-nuclear spectra of Mrk 231 exhibit broad Hα emission lines, which could be attributed to high-velocity outflows from the nucleus of Mrk 231, an extreme circumnuclear starburst, or a disturbed circumnuclear disc and broad line region associated with the merger of galaxies. The narrow Hα emission line has three components in every spectrum, which could be indicative of low-velocity outflows or a disturbed structure of the narrow-line region. The region to the south of the nucleus exhibits weak Hβ emission, and the regions to the north show no or extremely faint Hβ emission. The continuum has a stronger blue component in the south compared to the north. The central spectrum has prominent broad absorption lines at a redshift of ∼0.0262, which is distinct from the redshift of the emission line system, ∼0.0422. Broad absorption lines belonging to at least three systems are present in all of the off-nuclear spectra, but the regions to the south have their most prominent absorption lines at a redshift of ∼0.0262, and all three systems have absorption lines of similar strengths in the regions to the north. A careful examination of the acquisition images of Mrk 231 shows that there is diffuse emission in the region adjacent to the northern tail, extending in the north-east direction almost orthogonally, which might be an indication of a more complex interaction history.
High-resolution X-ray spectra of the compact binary supersoft X-ray source CAL 87
Authors: Pei Songpeng , Zhang Xiaowan , Li Qiang , Ou Ziwei
Published: August 2024

In this study we present an analysis of the archival X-ray data of the eclipsing supersoft X-ray binary CAL 87 observed with the Chandra Advanced CCD Imaging Spectrometer (ACIS) camera and Low Energy Transmission Grating (LETG) in 2001 August and with XMM-Newton in 2003 April. The high-resolution X-ray spectra are almost unchanged on the two different dates. The average unabsorbed X-ray luminosity during the exposure was 4.64 − 5.46 × 1036 ergs s−1 in 2001 and 4.54 − 4.82 × 1036 ergs s−1 in 2003, with prominent and redshifted emission lines, mostly of nitrogen, oxygen, iron, and argon, contributing to at least 30% of the X-ray flux. The continuum X-ray flux is at least an order of magnitude too low for a hot hydrogen-burning white dwarf (WD). However, the continuum flux is consistent with Thomson-scattering reflecting about 5% of the light of a hydrogen-burning WD with effective temperature of 800 000 K and a mass of ∼1.2 M⊙. It has been noted that a large Thomson-scattering corona explains the X-ray eclipse of CAL 87, in which the size of the eclipsed region is found to be on the order of a solar radius. The emission lines originate in an even more extended region beyond the eclipsed central X-ray source; the emission spectrum is very complex, with unusual line ratios.
Prospects of directly using closure traces for imaging in very long baseline interferometry
Authors: Müller Hendrik
Published: August 2024

Context. The reconstruction of the polarization of a source in radio interferometry is a challenging calibration problem since the reconstruction strongly depends on the gains and leakages, which need to be inferred along with the image. This is particularly true for the Event Horizon Telescope (EHT) due to its small number of antennas, low signal-to-noise ratio, and large gain corruptions.

Aims. To recover linear polarization, one has to either infer the leakages and gains together with the image structure or rely completely on calibration-independent closure quantities. While the first approach has been explored in very long baseline interferometry (VLBI) for a long time, the latter has been less studied for polarimetry.

Methods. Closure traces are a recently proposed concept of closure quantities that, in contrast to closure phases and closure amplitudes, are independent of both gains and leakages and carry the relevant information about the polarization of the source. Here we explore how closure traces can be directly fitted to create an image, and we identify an imaging pipeline that succeeds in direct imaging from closure traces.

Results. Since closure traces have a number of inherent degeneracies, multiple local image modes that can fit the data are detected. Therefore, a multi-objective imaging technique is needed to correctly sample this multi-modality.

Conclusions. Closure traces are not constraining enough for the current EHT configuration to recover an image directly, mainly due to the small number of antennas. For planned successors of the EHT, however (with a significantly larger number of antennas), this option will become feasible and will be competitive with techniques that use imaging with residual leakages.
Galaxy populations in the Hydra I cluster from the VEGAS survey
Authors: Spavone Marilena , Iodice Enrichetta , Lohmann Felipe S. , Arnaboldi Magda , Hilker Michael , La Marca Antonio , Calvi Rosa , Cantiello Michele , Corsini Enrico M. , D’Ago Giuseppe , Forbes Duncan A. , Mirabile Marco , Rejkuba Marina
Published: August 2024

In this paper, we analyse the light distribution in the Hydra I cluster of galaxies to explore their low surface brightness features, measure the intra-cluster light, and address the assembly history of the cluster. For this purpose, we used deep wide-field g- and r-band images obtained with the VLT Survey Telescope (VST) as part of the VEGAS project. The VST mosaic covers ∼0.4 times the virial radius (Rvir) around the core of the cluster, which enabled us to map the light distribution down to faint surface brightness levels of μg ∼ 28 mag/arcsec2. In this region of the cluster, 44 cluster members are brighter than mB ≤ 16 mag, and the region includes more than 300 dwarf galaxies. Similar to the projected distribution of all cluster members (bright galaxies and dwarfs), we find that the bulk of the galaxy light is concentrated in the cluster core, which also emits in the X-rays, and there are two overdensities: in the north (N) and south-east (SE) with respect to the cluster core. We present the analysis of the light distribution of all the bright cluster members. After removing foreground stars and other objects, we measured the diffuse intra-cluster light and compared its distribution with that of the globular clusters and dwarf galaxies in the cluster. We find that most of the diffuse light low surface brightness features, and signs of possible gravitational interaction between galaxies reside in the core and in the group in the N, while ram-pressure stripping is frequently found to affect galaxies within the SE group. All these features confirm that the mass assembly in this cluster is still ongoing. By combining the projected phase-space with these observed properties, we trace the different stages of the assembly history. We also address the main formation channels for the intra-cluster light detected in the cluster, which has a total luminosity of LICL ∼ 2.2 × 1011 L⊙ and contributes ∼12% to the total luminosity of the cluster.
Redução fechada assistida por Kapandji e fixação percutânea com fio de Kirschner em fraturas do úmero proximal em adolescentes: Nota técnica
Authors: Turazza Florencia , Zimmermann Faggion Heloisa , Masquijo Julio Javier
Published: August 2024

As fraturas proximais do úmero representam aproximadamente 3 a 5% de todas as fraturas pediátricas e em adolescentes, com maior incidência em crianças mais velhas, principalmente entre 10 e 15 anos de idade. Fraturas sem luxação ou com luxação mínima geralmente podem ser tratadas de forma conservadora. No entanto, o manejo das fraturas proximais do úmero com luxação ou instabilidade em adolescentes pode exigir intervenção cirúrgica; nesses casos, a redução fechada e a fixação percutânea (CRPP, na sigla em inglês) são as técnicas mais empregadas. A CRPP não é isenta de possíveis desafios e dificuldades potenciais. Este artigo tem como objetivo descrever uma técnica que pode facilitar a CRPP e minimizar as complicações associadas a esta abordagem cirúrgica.
Electronic properties and formation energy of chalcogen-doped (S/Se/Te) corundum Al2O3
Authors: Liao Yimin , Song Hanzhao , Xie Zhigao , Zhang Chuang , Han Zhuolun , Wang Yan , Tan Chee-Keong
Published: August 2024

α-Al2O3 is renowned for its extensive bandgap and diverse applications in electronic and optoelectronic devices. Employing density-functional theory-based methods, this study investigates the feasibility of chalcogen doping (S, Se, Te) in α-Al2O3. Standard modeling tools are utilized to construct α-Al2O3 supercells, focusing on the calculations of individual chalcogen-related and native point defects resulting from single-atom doping. Our analysis systematically explores the formation energies and transition levels associated with chalcogen (S, Se, Te) doping in oxygen (or aluminum) sites in Al-rich (or O-rich) limits. We observe a trend where increasing atomic number (from S to Te) correlates with a higher difficulty in forming anion-doped α-Al2O3, but a lower barrier to cationic doping. The results indicate a preferential substitution of chalcogen atoms for aluminum in O-rich environments. Specifically, in varying oxygen conditions, the dominant defect types, their prevalence, and defect formation energies in α-Al2O3 are significantly altered following chalcogen doping, offering new insights into defect processes in α-Al2O3.
Suppressing sidechain modes and improving structural resolution for 2D IR spectroscopy via vibrational lifetimes
Authors: Hess Kayla A. , Rohler Cade K. , Boutwell Dalton R. , Snyder Jason M. , Buchanan Lauren E.
Published: August 2024

Vibrational spectroscopy of protein structure often utilizes 13C18O-labeling of backbone carbonyls to further increase structural resolution. However, sidechains such as arginine, aspartate, and glutamate absorb within the same spectral region, complicating the analysis of isotope-labeled peaks. In this study, we report that the waiting time between pump and probe pulses in two-dimensional infrared spectroscopy can be used to suppress sidechain modes in favor of backbone amide I′ modes based on differences in vibrational lifetimes. Furthermore, differences in the lifetimes of 13C18O-amide I′ modes can aid in the assignment of secondary structure for labeled residues. Using model disordered and β-sheet peptides, it was determined that while β-sheets exhibit a longer lifetime than disordered structures, amide I′ modes in both secondary structures exhibit longer lifetimes than sidechain modes. Overall, this work demonstrates that collecting 2D IR data at delayed waiting times, based on differences in vibrational lifetime between modes, can be used to effectively suppress interfering sidechain modes and further identify secondary structures.
Empirically extending 1D Child–Langmuir theory to a finite temperature beam
Authors: Snelling Jesse M. , Werner Gregory R. , Cary John R.
Published: August 2024

Numerical solutions to the 1D steady-state Vlasov–Poisson system are used to develop a straightforward empirical formula for the electric current density transmitted through a vacuum diode (voltage gap) as a function of gap distance, gap voltage, the injected current density, and the average velocity and temperature of injected particles, as well as their charge and mass. This formula generalizes the 1D cold beam Child–Langmuir law (which predicts the maximum transmitted current for mono-energetic particles in a planar diode as a function of gap voltage and distance) to the case where particles are injected with a finite velocity spread. Though this case is of practical importance, no analytical solution is known. Found by a best fit to results from particle-in-cell simulations, the empirical formula characterizes the current transmitted across the diode for an injected velocity distribution of a drifting Maxwellian. It is not meant to yield a precise answer, but approximately characterizes the effect of space charge on transmitted current density over a large input space. The formula allows quick quantitative estimation of the effect of space charge in diode-like devices, such as gate-anode gaps in nanoscale vacuum channel transistors.
Impact of partial shading on the performance and reliability of potential-induced degraded crystalline silicon PV module
Authors: S Asokan , Kumar Ravi , Puranik Vishal E. , Gupta Rajesh
Published: August 2024

Potential-induced degradation shunting (PID-s) is a severe degradation mechanism that significantly impacts the performance and lifespan of photovoltaic (PV) modules. The impact of PID-s is further intensified when it coincides with partial shading. Despite its significance, limited research has been focused on the combined impact of PID-s and partial shading. Therefore, this work analyzes the impact of partial shading on the performance and reliability of PID-s-affected PV module. In the literature, PID-s is reported with two natures: Ohmic and non-Ohmic. This work considers the nature and severity of PID-s in the presented investigation. Results indicate that when an Ohmic PID-s-affected PV cell is shaded in a module, it results in less power loss than when a healthy cell is shaded, but it induces a significantly high reverse current through the PID-s-affected cell. With severity, the impact of Ohmic PID-s under shading decreases. In the case of non-Ohmic PID-s, severity does not impact the performance significantly; however, shading of a non-Ohmic PID-s affected cell is more severe than Ohmic PID-s until the PID-s threshold is reached. Furthermore, bypass diode activation is delayed in both types of PID-s compared to shading on healthy cells. Overall, these findings emphasize the significance of optimizing shading strategies and mitigating PID-s effects to enhance the performance and reliability of photovoltaics. This research provides valuable insights for industry stakeholders involved in PV installation and maintenance operations.
The effect of multi-tasks mechanism on cooperation in evolutionary game
Authors: Fan Jiarui , Du Haifeng , Li Guangyu , He Xiaochen
Published: August 2024

Human games are inherently diverse, involving more than mere identity interactions. The diversity of game tasks offers a more authentic explanation in the exploration of social dilemmas. Human behavior is also influenced by conformity, and prosociality is a crucial factor in addressing social dilemmas. This study proposes a generalized prisoner’s dilemma model of task diversity that incorporates a conformity-driven interaction. Simulation findings indicate that the diversity of multi-tasks and the path dependence contribute to the flourishing of cooperation in games. Conformity-driven interactions also promote cooperation. However, this promotion effect does not increase linearly, and only appropriate task sizes and suitable proportions of conformity-driven interactions yield optimal results. From a broader group perspective, the interplay of network adaptation, task size, and conformity-driven interaction can form a structure of attractors or repellents.
Extreme ultraviolet laser ablation and time-of-flight mass spectrometry of gold, aluminum, and copper targets
Authors: Wilson S. A. , Rush L. A. , Solis Meza E. , Lolley J. A. , Rocca J. J. , Menoni C. S. , Tallents G. J.
Published: August 2024

An ablation crater depth estimation model, founded on the concept of an ionizing bleaching wave, has been developed for metal targets irradiated by an extreme ultraviolet (EUV) laser. Two EUV capillary discharge lasers operating at a wavelength of 46.9 nm were focused onto targets of gold, aluminum, and copper using two different experimental setups to maximize the laser fluence range. The experimental ablation craters were measured using an atomic force microscope, and the depths were compared to the ionizing wave model. The model depends on the dominant ion charge of the ablated plasma, which was measured experimentally using the low fluence setup with a time-of-flight mass spectrometer. The measured ablation depths and ion charges at low fluences are in agreement with the model. The ablation crater depths in the higher fluence range confirmed the trends predicted by the model, showing potential to expand its use to other materials and fluence ranges.
Delayed fragmentation of isolated nucleobases induced by MeV ions
Authors: Nakao T. , Takasu R. , Tsuchida H. , Saito M. , Majima T.
Published: August 2024

We evaluated the dissociation of isolated gas-phase nucleobase molecules induced by mega electron volt (MeV)-energy ions to gain fundamental insights into the reactions of nucleobases upon fast ion irradiation. We studied five nucleobase molecules—adenine, guanine, cytosine, thymine, and uracil—as gas-phase targets. We compared the fragmentation patterns obtained from carbon ion impacts with those obtained from proton impacts to clarify the effect of heavy ion irradiation. We also compared the results with electron impact and photoionization results. In addition, we identified several delayed fragmentation pathways by analyzing the correlation between fragment pairs generated from singly and doubly charged intermediate ions. To determine the lifetimes of delayed fragmentation from singly charged intermediate ions, we evaluated the detection efficiencies of the microchannel plate detector for the neutral fragment HCN as a function of kinetic energy using a new methodology. As the first demonstration of this method, we estimated the lifetimes of C5H5N5+ generated by 1.2-MeV C+ and 0.5-MeV H+ collisions to be 0.87 ± 0.43 and 0.67 ± 0.09 µs, respectively. These lifetimes were approximately one order of magnitude longer than those of the doubly charged intermediate ion C5H5N52+.
Integrating discrete sub-grid filters with discretization-corrected particle strength exchange method for high Reynolds number flow simulations
Authors: Obeidat Anas
Published: August 2024

We present a discrete filter for subgrid-scale model, coupled with the discretization corrected particle strength exchange method, for the simulation of three-dimensional viscous incompressible flow at high Reynolds flows. The majority of turbulence modeling techniques, particularly in complex geometries, face significant computational challenges due to the difficulties in implementing three-dimensional (3D) convolution operations for asymmetric boundary conditions or curved domain boundaries. In this contribution, Taylor expansion is used to define differential operators corresponding to the convolution filter, so that the transfer function remains very close to the unity of sizeable displacement in wave number, making the filter a good approximation to the convolution one. A discrete Gaussian filter, in both fourth and second-order forms, was evaluated with varying ratios of particle spacing to the cutoff length. The impact of the filter's order and the ratio's value is thoroughly examined and detailed in the study. Additionally, the Brinkman penalization technique is employed to impose boundary conditions implicitly, allowing for efficient and accurate flow simulations around complex geometries without the need for modifying the numerical method or computational domain. The incompressible flow is governed by the entropically damped artificial compressibility equations allowing explicit simulation of the incompressible Navier–Stokes equations. The effectiveness of the proposed methodology is validated through several benchmark problems, including isotropic turbulence decay, turbulent channel flow, and flow around four cylinders arranged in a square in-line configuration, which are representative but not exhaustive of the full range of engineering applications. These test cases demonstrate the method's accuracy in capturing the intricate flow structures characteristic of high Reynolds number flows (up to 15k), highlighting its applicability to turbulence modeling.
Spectral condensation and bidirectional energy transfer in quasi-geostrophic turbulence above small-scale topography
Authors: Zhang Lin-Fan , Xie Jin-Han
Published: August 2024

Seafloor topography is essential for oceanic fluid dynamics from many perspectives, and it is believed to enhance energy dissipation in oceanic flows. This study numerically examines the impact of small-scale topography on the dynamics of quasi-geostrophic barotropic flows and finds three regimes and two critical values of topographic magnitude. In the first regime, where the topographic magnitude is below the first critical value, small-amplitude topography extends the range of upscale energy flux and enhances condensation, contradicting the common understanding of topographic damping. In the second regime, where the topography magnitude lies between the two critical values, energy simultaneously transfers to both large and small scales, and topography induces extra dissipation at the topographic scale. A second critical topography magnitude exists, corresponding to a second-order phase transition. When the topography magnitude exceeds the second critical value, energy only transfers downscale. The discovery of counterintuitive topography-enhanced energy flux and its critical phenomenon brings new challenges to topography parameterization in ocean models.
Vibrational heavy atom effect on relaxation and solvent shell dynamics in group VIII trimetallic carbonyls
Authors: Rey Melissa J. , Reilly Connor J. , Massari Aaron M.
Published: August 2024

Infrared pump-probe and two-dimensional infrared (2D-IR) spectroscopies were used to study the vibrational dynamics of a homologous set of trimetallic dodecacarbonyls with increasingly heavy atomic masses in tetrahydrofuran solution. The vibrational lifetimes showed some evidence of the vibrational heavy atom effect (VHAE) but were not consistent across the sample set. Spectral diffusion was measured by 2D-IR spectroscopy to investigate whether the changes produced by the VHAE had influenced other aspects of vibrational dynamics. The triiron species was found to be more dynamic on very fast timescales and may exhibit evidence of a transient bridging CO structure. Centerline slope analysis of the high-frequency CO peak for each complex revealed that the vibrational dynamics were subtly but consistently slowed for the compounds with heavier metal atoms.
Tuning the excitation laser power in a stochastic optical reconstruction microscope for Alexa Fluor 647 dye in Vectashield mounting media
Authors: Kumar Amalesh , Bharadwaj Anupam , Choudhury Pranjal , Mathew Sam P. , Jaganathan Bithiah Grace , Boruah Bosanta R.
Published: August 2024

Super-resolution imaging techniques have fundamentally changed our understanding of cellular architecture and dynamics by surpassing the diffraction limit and enabling the visualization of subcellular details. The popular super-resolution method known as stochastic optical reconstruction microscopy (STORM) relies on the exact localization of single fluorescent molecules. The significance of employing Vectashield as a mounting medium for the super-resolution imaging scheme called direct STORM has recently been explored. Alexa Fluor 647 (AF647), one of the most popular dyes, shows significant blinking in Vectashield. However, to observe prominent blinking of the fluorophore for the reconstruction of super-resolved images, the power of the excitation laser needs to be tuned. This work demonstrates the tuning of excitation power density in the sample plane for superior imaging performance using AF647 in Vectashield. Samples comprising MDA-MB-231 breast cancer cell line are used for the experiments. The actin filaments of the cell are stained with phalloidin-conjugated AF647 dye. For the experiment, we employ a low-cost openFrame-based STORM system equipped with a programmable Arduino-regulated laser source emitting at 638 nm. An excitation power density of 0.60 kW/cm2 at 638 nm in the sample plane is observed to maximize the signal-to-noise ratio, the number of switching events, and the number of photons detected per event during image acquisition, thereby leading to the best imaging performance in terms of resolution. The outcome of this work will promote further STORM-based super-resolved imaging applications in cell biology using Alexa Fluor 647 in Vectashield.
COSMONAUT: A COmpact spectrometer for measurements of neutrons at the ASDEX upgrade tokamak
Authors: Nocente M. , Molin A. Dal , Rigamonti D. , Rosa M. Dalla , Fernández B. , Fugazza S. , Guerrero C. , Gorini G. , Kazakov Y. , Tardini G. , Tardocchi M. ,   ASDEX Upgrade Team,   Eurofusion Tokamak Exploitation Team
Published: August 2024

A COmpact Spectrometer for Measurements Of Neutrons at the ASDEX Upgrade Tokamak (COSMONAUT) has been developed for spectroscopy measurements of the 2.45 MeV neutron emission from deuterium plasmas at the ASDEX Upgrade. The instrument is based on a CLYC-7 inorganic scintillator, whereby the detection of fusion neutrons occurs via their interaction with 35Cl nuclei in the detector crystal, leading to a peak in the detector response function and providing excellent neutron/gamma-ray discrimination capabilities. The diagnostics is installed along a radial line of sight and makes use of a digital system to record time resolved data for the whole duration of the discharge. Measurements in ASDEX Upgrade plasmas with neutral beam injection have been carried out and are successfully interpreted using state-of-the-art modeling codes. Next step applications of the diagnostics are in experiments aimed at generating energetic particles by ion cyclotron resonance heating schemes. In these scenarios, COSMONAUT will provide unique information on the acceleration of deuterons beyond the beam injection energy and on their confinement, for comparison with modeling.
A faster algorithm for the free energy in one-dimensional quantum systems
Authors: Scalet Samuel O.
Published: August 2024

We consider the problem of approximating the free energy density of a translation-invariant, one-dimensional quantum spin system with finite range. While the complexity of this problem is nontrivial due to its close connection to problems with known hardness results, a classical subpolynomial-time algorithm has recently been proposed [Fawzi et al., 2022]. Combining several algorithmic techniques previously used for related problems, we propose an algorithm outperforming this result asymptotically and give rigorous bounds on its runtime. Our main techniques are the use of Araki expansionals, known from results on the nonexistence of phase transitions, and a matrix product operator construction. We also review a related approach using the Quantum Belief Propagation [Kuwahara et al., 2018], which in combination with our findings yields an equivalent result.
A sensitivity-enhanced sunlight-driven quantum magnetometer via level anti-crossing
Authors: Zhu Yunbin , Jing Ke , Rong Xing , Xie Yijin , Du Jiangfeng
Published: August 2024

Nitrogen-vacancy (NV) centers in diamond have emerged as a robust room-temperature solid-state platform for weak magnetic field detection. Several NV-based magnetometers have been proposed in the past decades, but they still suffer from either low sensitivity or high power consumption. This is a challenge for sensors deployed in remote locations on Earth or in space that are not connected to the power grid. Although sunlight-driven quantum magnetometry, which does not rely on conventional energy sources, has been proposed as a possible solution, its sensitivity remains a limitation. Here, we present an impressive improvement in the sensitivity of the sunlight-driven NV-diamond quantum magnetometer. A crucial aspect of our approach involves leveraging the ground-state level anti-crossing properties of the NV centers, coupled with magnetic flux concentrators. This integration enables us to achieve a magnetic-field sensitivity of 26 pT/Hz in a laboratory environment and 49 pT/Hz when the magnetometer operates outdoors under sunlight. We also illustrate the promising potential of further improving the sensitivity to the subpicotesla level by using cutting-edge technologies. Furthermore, we reveal the capability of this quantum magnetometer as a receiver of extremely low-frequency magnetic signals and pave the way for communication applications. These advancements represent a significant leap toward attaining high-sensitivity and energy-efficient magnetic field sensing and expanding the range of possible applications for these environmentally sustainable quantum technologies.
Design of a multichannel vacuum ultraviolet spectroscopy system for SPARC
Authors: Song I. , Reinke M. L. , Raimond J. L. , Ferrera A. , Miner I. , Saltos A. A.
Published: August 2024

The design of a vacuum ultraviolet spectroscopy system has been performed to monitor and provide feedback for impurity control in SPARC. The spectrometer, covering a wavelength range of 10–2000 Å through a flat-field configuration with diffraction gratings, incorporates five survey lines of sight. This allows for comprehensive impurity analysis across the core and four divertor regions (inner/outer and upper/lower). Its compact modular design facilitates vertical stacking of each spectrometer unit, significantly reducing space in the tokamak hall, where a dedicated radiation shielding bunker will be built. Safety features include a secondary helium enclosure to mitigate tritium permeation risks during deuterium–tritium (D–T) operations and shielding within the beamlines for enhanced radiation protection. The silicon carbide mirror design for divertor observation ensures its survivability in the in-vessel environment of SPARC, validated by thermal and electromagnetic analysis. Signal modeling and data acquisition testing results show that an exposure time of a few milliseconds is appropriate considering photon flux reaching the detector, demonstrating the system’s capability for discharge control that includes disruption avoidance.
Dynamics of a deformable compound droplet under pulsatile flow
Authors: Lanjewar Shubham , Ramji Sundari
Published: August 2024

The motion of a deformable compound droplet flowing within a confined channel in response to a pulsatile flow is numerically investigated. Toward this, an in-house solver based on the level-set method is developed. It is shown that a low Strouhal number leads to significant oscillation in flow velocity and a greater deformation of the compound droplet, driving it periodically along the streamwise direction resulting in an increased residence time, as compared to steady imposed flow. Conversely, high Strouhal number results in smaller amplitude oscillations in flow velocity leading to smoother droplet motion and lower deformation. Expectedly, a decrease in the pulsatile flow amplitude yields smoother and more uniform flow with reduced droplet deformation. Importantly, hitherto unreported cross-stream migration of an off-centered compound droplet under pulsatile flow is investigated. An off-centered compound droplet migrates toward the center of the channel, with its core being eccentric toward the wall it was initially close to. The influence of other key parameters such as density ratio, size ratio of the core, and the viscosity ratio of the shell in shaping the dynamics of the compound droplet is systematically explored. It is revealed that the eccentricity of the core can be manipulated by tuning inlet flow and density of core fluid. A more viscous shell results in a marginally higher film thickness near the wall and a higher droplet residence time within the channel. A higher Bond number results in a larger droplet deformation, resulting in a streamlined shape and significantly higher droplet speed.
Structure and lattice symmetry tailoring in monolayer SnTe epitaxially grown on Au(111)
Authors: Liao Qin , Xie Sheng-Yi , Xu Shicheng , Zhang Li , Tao Yanlin , Tian Qiwei , Zhang Chen , Li Bo , Tian Yuan , Yin Long-Jing , Zhang Lijie , Qin Zhihui
Published: August 2024

SnTe, as one type of topological crystal insulator (TCI), has crystal-symmetry-protected surface states, which is sensitive to its structure and lattice symmetry. Herein, the monolayer SnTe was well synthesized, presenting with tetragonal and hexagonal lattice symmetries, respectively. The lattice symmetry was found to be connected with precursors, as thermal evaporation of SnTe compounds led to a tetragonal type symmetry while co-deposition of Sn and Te elements can synthetize the hexagonal type. As a consequence of lattice mismatch with the underlying Au(111) substrate, SnTe with tetragonal lattice exhibits reconstructive stripe pattern, which would transform into hexagonal lattice symmetry with moiré pattern upon annealing at high temperature. Due to coupling with the substrate, SnTe exhibits metallicity in both symmetries, verified by corresponding differential conductance spectra (dI/dV). Comparative study on Cu(111) substrate was carried out and only copper telluride structures were formed, which may be related to the stronger surface decomposition of SnTe precursors on Cu(111) and direct copper tellurizing. Our work paves a practical way to control the surface structure and lattice symmetry of SnTe, providing a promising candidate for potential TCI applications.
Quantum nature of reactivity modification in vibrational polariton chemistry
Authors: Ke Yaling , Richardson Jeremy O.
Published: August 2024

In this work, we present a mixed quantum–classical open quantum system dynamics method for studying rate modifications of ground-state chemical reactions in an optical cavity under vibrational strong-coupling conditions. In this approach, the cavity radiation mode is treated classically with a mean-field nuclear force averaging over the remaining degrees of freedom, both within the system and the environment, which are handled quantum mechanically within the hierarchical equations of motion framework. Using this approach, we conduct a comparative analysis by juxtaposing the mixed quantum–classical results with fully quantum-mechanical simulations. After eliminating spurious peaks that can occur when not using the rigorous definition of the rate constant, we confirm the crucial role of the quantum nature of the cavity radiation mode in reproducing the resonant peak observed in the cavity frequency-dependent rate profile. In other words, it appears necessary to explicitly consider the quantized photonic states in studying reactivity modification in vibrational polariton chemistry (at least for the model systems studied in this work), as these phenomena stem from cavity-induced reaction pathways involving resonant energy exchanges between photons and molecular vibrational transitions.
Donnan equilibrium in charged slit-pores from a hybrid nonequilibrium molecular dynamics/Monte Carlo method with ions and solvent exchange
Authors: Kim Jeongmin , Rotenberg Benjamin
Published: August 2024

Ion partitioning between different compartments (e.g., a porous material and a bulk solution reservoir), known as Donnan equilibrium, plays a fundamental role in various contexts such as energy, environment, or water treatment. The linearized Poisson–Boltzmann (PB) equation, capturing the thermal motion of the ions with mean-field electrostatic interactions, is practically useful to understand and predict ion partitioning, despite its limited applicability to conditions of low salt concentrations and surface charge densities. Here, we investigate the Donnan equilibrium of coarse-grained dilute electrolytes confined in charged slit-pores in equilibrium with a reservoir of ions and solvent. We introduce and use an extension to confined systems of a recently developed hybrid nonequilibrium molecular dynamics/grand canonical Monte Carlo simulation method (“H4D”), which enhances the efficiency of solvent and ion-pair exchange via a fourth spatial dimension. We show that the validity range of linearized PB theory to predict the Donnan equilibrium of dilute electrolytes can be extended to highly charged pores by simply considering renormalized surface charge densities. We compare with simulations of implicit solvent models of electrolytes and show that in the low salt concentrations and thin electric double layer limit considered here, an explicit solvent has a limited effect on the Donnan equilibrium and that the main limitations of the analytical predictions are not due to the breakdown of the mean-field description but rather to the charge renormalization approximation, because it only focuses on the behavior far from the surfaces.
Novel flexible fixed-time stability theorem and its application to sliding mode control nonlinear systems
Authors: Liu Jingang , Li Ruiqi , Zheng Jianyun , Bu Lei , Liu Xianghuan
Published: August 2024

For the fixed-time nonlinear system control problem, a new fixed-time stability (FxTS) theorem and an integral sliding mode surface are proposed to balance the control speed and energy consumption. We discuss the existing fixed time inequalities and set up less conservative inequalities to study the FxTS theorem. The new inequality differs from other existing inequalities in that the parameter settings are more flexible. Under different parameter settings, the exact upper bound on settling time in four cases is discussed. Based on the stability theorem, a new integral sliding mode surface and sliding mode controller are proposed. The new control algorithm is successfully applied to the fixed-time control of chaotic four-dimensional Lorenz systems and permanent magnet synchronous motor systems. By comparing the numerical simulation results of this paper’s method and traditional fixed-time sliding mode control (SMC), the flexibility and superiority of the theory proposed in this paper are demonstrated. Under the same parameter settings, compared to the traditional FxTS SMC, it reduces the convergence time by 18%, and the estimated upper bound of the fixed time reduction in waiting time is 41%. In addition, changing the variable parameters can improve the convergence velocity.
Nonlinear Poisson–Boltzmann solutions for charged parallel plates: When opposite charges repel
Authors: Travesset Alex
Published: August 2024

I present an exact solution of the Poisson–Boltzmann equation for two parallel plates and discuss the solution properties. I discuss in more detail plates with opposite charges: In this case, there are two critical separations, Lc,1 < Lc,2. For separations less than Lc,1, the force between plates is repulsive. It switches to attractive at Lc,1, but with the electric potential having the same sign on both plates. For L > Lc,2, the force remains attractive, and the potential at the plates has the same sign as the charge on each plate. I also describe charge regulation, determined by pKa, and provide formulas for both the critical distance where oppositely charged plates repel and their charging process. The implications of these results for the nanoparticle assembly, as driven by electrostatic interactions, are also discussed.
Critical adsorption and charge reversal in polyelectrolyte solutions: Analytical mean-field theory
Authors: Martens C. M.
Published: August 2024

An analytical linearized mean-field theory is presented to describe the adsorption behavior of polyelectrolytes near charged colloidal surfaces with additional short-ranged non-electrostatic interactions. The coupling between the polyelectrolyte segment density and electrostatic potential is explicitly accounted for in a self-consistent manner. This coupling gives rise to highly non-linear behavior, such as oscillations of the electrostatic potential. We derive analytical expressions for the critical surface charge density σc, after which adsorption takes place, and recover the well-known σc∼ns3/2 scaling regime, where ns is the salt concentration. In addition, the theory yields a new ns1 scaling regime if the surface is hard and a unified ns1 scaling regime if the surface also possesses some short-ranged attraction with the polyelectrolyte. Furthermore, we derive an analytical expression to describe the critical polyelectrolyte concentration φc to achieve complete charge reversal, which is found to scale as φc ∼ σ2/(f2c2), where c is related to the magnitude of short-ranged interactions and f is the average charge per monomer of the polyelectrolyte. It is observed that within our theory, complete charge reversal can only take place if the short-ranged interactions are sufficiently strong to completely compensate for the entropy loss of adsorption.
Impedance matching in optically induced dielectrophoresis: Effect of medium conductivity on trapping force
Authors: Zaman Mohammad Asif , Wu Mo , Ren Wei , Hesselink Lambertus
Published: August 2024

An impedance analysis for optically induced dielectrophoresis is presented. A circuit model is developed for this purpose. The model parameters are fully defined in terms of the geometrical and material properties of the system. It is shown that trapping force can only be generated when the material properties follow certain impedance matching conditions. The impedance match factor is introduced to succinctly quantify the phenomenon. It is used to calculate bounds on the allowed electrical conductivity of the suspension medium. Results from the proposed model are found to be in good agreement with full-wave numerical simulations. By computing the acceptable set of material parameters with little computational cost, the presented analysis can streamline ODEP system design for various applications.
Five-molecule water clusters have liquid-like properties
Authors: Miller Johanna L.
Published: August 2024

With theory-guided rotational spectroscopy measurements—and some help from nuclear spin—researchers can tell whether a hydrogen chloride molecule in a tiny amount of water is dissolved.