jablonkagroup/rise_ai_scientists huggingface dataset:
Authors: Adrián Portela‐González | Enrique Mendez‐Vega | Wolfram Sander
Source: Journal of Physical Organic Chemistry (article, 2023-05-16)
Field: Chemistry — Physical and Theoretical Chemistry

2,3,5,6‐Tetrafluoro‐1,4‐phenylenedinitrene: A dinitrene with near degenerate singlet and triplet states Abstract The dinitrene 2,3,5,6‐tetrafluoro‐1,4‐phenylenedinitrene was synthesized by photolysis of matrix‐isolated 1,4‐diazido‐2,3,5,6‐tetrafluorobenzene at 365 or 405 nm in high yields at cryogenic temperatures and characterized by FT‐IR, UV‐Vis, and EPR spectroscopy. The electronic structure of the dinitrene is described best as a quinoidal diradical with an open‐shell singlet ground state and a triplet state laying only 650 ± 5 cal/mol higher in energy. Irradiation with λ = 254 nm results in fragmentation of the dinitrene into FCCF and several olefins which on prolonged photolysis fragment into FCCCN, FCCNC, and FCN. Diradical ; Chemistry ; Singlet state ; Photodissociation ; Photochemistry ; Triplet state ; Electron paramagnetic resonance ; Degenerate energy levels ; Spectroscopy ; Ground state ; Fragmentation (computing) ; Open shell ; Molecule ; Excited state ; Atomic physics ; Nuclear magnetic resonance ; Organic chemistry Chemical Reactions and Mechanisms ; Advanced Chemical Physics Studies ; Photochemistry and Electron Transfer Studies
Authors: Sarju Adhikari | Abu M. Rustum
Source: Journal of AOAC International (article, 2023-03-15)
Field: Chemistry — Spectroscopy

Improved Stability-Indicating RP-UPLC Method for the Levamisole Hydrochloride Assay and Estimation of Its Related Compounds Abstract Background Levamisole hydrochloride (LVM) is an anthelmintic drug substance with immunomodulatory and anticancer activities. LVM has also found usage as a cutting agent in street cocaine. Objective This study was aimed to develop and validate an alternative and improved stability-indicating reversed-phase ultraperformance liquid chromatography (RP-UPLC) method for the determination of LVM and the estimation of its related compounds. Method The UPLC method for the assay was optimized in terms of organic solvents consumed, pH, column temperature, and flow rate. Determination of LVM and its related compounds was performed using a gradient elution on a Waters ACQUITY UPLC® BEH C18 (50 mm × 2.1 mm i.d., 130 Å). The column temperature was maintained at 35°C. Mobile phase A was composed of aqueous 5 mM ammonium hydroxide, and mobile phase B was composed of acetonitrile. All the analytes were monitored by UV detection at 215 nm with a flow rate of 0.7 mL/min. The total runtime of the method with column equilibration is 4.0 min. Results The developed method met all the acceptance criteria of the current International Council for Harmonization [ICH Q2 (R1)] guidelines. The method was tested in terms of specificity, linearity (R2 &amp;gt; 0.999), limit of detection (LOD; 0.06 μg/mL), limit of quantitation (LOQ; 0.2 μg/mL), accuracy, precision, and robustness. With a short analysis time (&amp;lt;2.5 min) and reduced consumption of organic solvents, the proposed method is considered a greener alternative to conventional chromatographic methods. Conclusions An alternative and improved UPLC method was successfully developed and validated in accordance with the ICH guidelines for the determination of LVM and the estimation of its related compounds. Highlights Due to its high degree of selectivity, speed, and accuracy, the developed method can significantly benefit the end-users with laboratory efficiency and throughput during routine analysis of production batches and stability monitoring of LVM-related drug products. Levamisole ; Chromatography ; Chemistry ; Hydrochloride ; High-performance liquid chromatography ; Stability (learning theory) ; Computer science ; Biology ; Immunology ; Organic chemistry ; Machine learning Analytical Chemistry and Chromatography ; Analytical Methods in Pharmaceuticals ; Advanced Chemical Sensor Technologies
Authors: Torben Steenbock | Tobias Dittmann | Surender Kumar | Gabriel Bester
Source: ChemRxiv (preprint, 2023-07-25)
Field: Materials Science — Materials Chemistry

Ligand-Induced Symmetry Breaking as Origin of Multiexponential Photoluminescence Decay in CdSe Quantum Dots The bright photoluminescence (PL) of colloidal CdSe quantum dots (QDs) makes them interesting for optical applications. For most of them well-defined PL properties, dominated by a single excitonic state, are required. However, in many PL experiments on QD ensembles multiexponential decay was observed. Based on spin-orbit density functional theory and screened configuration interaction calculations, we show that highly symmetric and defect-free CdSe QDs with diameters of 1.7 nm and 2.0 nm possess a multiexponential PL at the single-dot level. This is a consequence of a ligand-induced symmetry breaking with a subsequent rearrangement of the lowest eight excitonic states in two sets of four singly degenerate excitonic states. For each set, the lowest state is dark and the other three bright. We find that the splitting between the sets can be modified by the ligand coverage and the ligand choice, which facilitates engineering the PL properties of CdSe QDs. Quantum dot ; Photoluminescence ; Degenerate energy levels ; Ligand (biochemistry) ; Symmetry (geometry) ; Symmetry breaking ; Condensed matter physics ; Chemistry ; Physics ; Molecular physics ; Chemical physics ; Optoelectronics ; Quantum mechanics Quantum Dots Synthesis And Properties ; Chalcogenide Semiconductor Thin Films ; Nanocluster Synthesis and Applications
Authors: Yun Chen | Lu Tang | Houdao Cai | Meiyun Zhang | Xunjie Wang | Cuidi Feng | Wenbo Xiao | Huaming Zhang
Source: Magnetic Resonance in Chemistry (article, 2023-11-17)
Field: Materials Science — Materials Chemistry

Theoretical studies on the local structure and spin Hamiltonian parameters for Cu <sup>2+</sup> ions in LiTaO <sub>3</sub> crystal The local structure and spin Hamiltonian parameters (SHPs) g factors (g<sub>x</sub> , g<sub>y</sub> , g<sub>z</sub> ) and the hyperfine structure constants (A<sub>x</sub> , A<sub>y</sub> , A<sub>z</sub> ) for Cu<sup>2+</sup> doped in the LiTaO<sub>3</sub> crystal are theoretically investigated by the perturbation formulas for a 3d<sup>9</sup> ion under rhombically elongated octahedral based on the cluster approach. The impurity Cu<sup>2+</sup> was assumed to occupy the host trigonally-distorted octahedral Li<sup>+</sup> site and experience the Jahn-Teller (JT) distortion from the host trigonal octahedral [TaO<sub>6</sub> ]<sup>10-</sup> to the impurity rhombically elongated octahedral [CuO<sub>6</sub> ]<sup>10-</sup> . Based on the calculations, the impurity-ligand bond lengths parallel and perpendicular to the C<sub>2</sub> -axis are found to be R<sub>||</sub> (≈ 2.305 Å) and R<sub>⊥</sub> (≈ 2.112 Å) for the studied [CuO<sub>6</sub> ]<sup>10-</sup> cluster, with the planar bond angle θ (≈ 78.2°). Meanwhile, the ground-state wave function for Cu<sup>2+</sup> center in LiTaO<sub>3</sub> was also obtained. The calculated SHPs based on the above local lattice distortions agree well with the experimental data, and the results are discussed. Chemistry ; Octahedron ; Hyperfine structure ; Impurity ; Ion ; Crystal structure ; Crystallography ; Bond length ; Jahn–Teller effect ; Electron paramagnetic resonance ; Condensed matter physics ; Molecular physics ; Atomic physics ; Nuclear magnetic resonance ; Physics Luminescence Properties of Advanced Materials ; Advanced Condensed Matter Physics ; Inorganic Chemistry and Materials
Authors: A. Chan | Ming‐Hin Chau | Yikun Ren | Jia‐Jun Jiang | Man‐Kin Wong | Franco King‐Chi Leung
Source: ChemPlusChem (article, 2023-07-26)
Field: Materials Science — Biomaterials

Controlled Supramolecular Assemblies of Chiral Cyclometalated Gold (III) Amphiphiles in Aqueous Media Gold (III) cyclometalated based amphiphiles in aqueous media have been revealed with excellent supramolecular transformations to external stimuli to open new pathways for soft functional material fabrications. Herein, we report a new chiral cyclometalated gold (III) amphiphile (GA) assembling into lamellar nanostructures in aqueous media confirmed with transmission electron microscopy (TEM). Counterion exchange with D-, L-, or racemic-camphorsulfonates features the significant supramolecular helicity enhancements, enabling transformations of GA from lamellar structure to vesicles and to nanotubes with multi-equivalents of counterion. The limited cytotoxicity of GA in aqueous media exhibits good biocompatibility. Amphiphile ; Supramolecular chemistry ; Lamellar structure ; Counterion ; Aqueous solution ; Biocompatibility ; Chemistry ; Supramolecular chirality ; Nanotechnology ; Supramolecular assembly ; Transmission electron microscopy ; Materials science ; Combinatorial chemistry ; Chemical engineering ; Organic chemistry ; Copolymer ; Crystallography ; Crystal structure ; Ion Supramolecular Self-Assembly in Materials ; Nanocluster Synthesis and Applications ; Dendrimers and Hyperbranched Polymers
Authors: Kayla Cole-Piepke | P. Nakarmi | Alicia Koenig | Gregory B. Thompson | Tim Mewes | Claudia Mewes | Ronald D. Noebe | Alex Leary
Source: Magnetochemistry (article, 2023-05-23)
Field: Materials Science — Electronic, Optical and Magnetic Materials

Influence of Mn Doping on Local Spin Moments and Stacking Fault Energies in Co(Mn) Alloys We report on the results of first principles calculations investigating the influences of Mn doping on the local moments and stacking fault energies (SFEs) in the Co95.8Mn4.2 and Co91.6Mn8.4 systems as compared to pure face-centered cubic Co. A supercell was developed to maintain periodicity in calculations, provide a simple relaxation mechanism, and allow for easy expansion to accommodate different concentrations of Mn. Calculations to determine the generalized SFE were performed on relaxed and non-relaxed systems in both ferromagnetic and nonmagnetic states. Analysis revealed fluctuations in the magnetic moments that are closely tied to the relaxation state and faulting state of the system. In the case of systems containing Mn, we observed a dependence of the SFE on the location of the Mn atom(s) within the supercell relative to the stacking fault interface and a strong induced magnetic moment for these atoms. Supercell ; Magnetic moment ; Condensed matter physics ; Stacking fault ; Atom (system on chip) ; Ferromagnetism ; Stacking ; Relaxation (psychology) ; Doping ; Spin (aerodynamics) ; Materials science ; Chemistry ; Physics ; Thermodynamics ; Dislocation Magnetic Properties and Applications ; Magnetic properties of thin films ; Magnetic Properties of Alloys
Authors: Wolfgang Hornfeck
Source: Acta Crystallographica Section A Foundations and Advances (article, 2023-10-31)
Field: Materials Science — Materials Chemistry

Chiral spiral cyclic twins. II. A two-parameter family of cyclic twins composed of discrete circle involute spirals A mathematical toy model of chiral spiral cyclic twins is presented, describing a family of deterministically generated aperiodic point sets. Its individual members depend solely on a chosen pair of integer parameters, a modulus m and a multiplier μ. By means of their specific parameterization they comprise local features of both periodic and aperiodic crystals. In particular, chiral spiral cyclic twins are composed of discrete variants of continuous curves known as circle involutes, each discrete spiral being generated from an integer inclination sequence. The geometry of circle involutes does not only provide for a constant orthogonal separation distance between adjacent spiral branches but also yields an approximate delineation of the intrinsically periodic twin domains as well as a single aperiodic core domain interconnecting them. Apart from its mathematical description and analysis, e.g. concerning its circle packing densities, the toy model is studied in association with the crystallography and crystal chemistry of α-uranium and CrB-type crystal structures. Aperiodic graph ; Involute ; Spiral (railway) ; Geometry ; Mathematics ; Integer (computer science) ; Crystallography ; Mathematical analysis ; Combinatorics ; Chemistry ; Computer science Quasicrystal Structures and Properties ; Origins and Evolution of Life ; Nonlinear Dynamics and Pattern Formation
Authors: D. Kumar | Pankaj Pandey | Lakhan Patidar
Source: International Journal for Research in Applied Science and Engineering Technology (article, 2023-01-13)
Field: Materials Science — Polymers and Plastics

Structural Analysis of Airplane Wing Using Composite and Natural Fiber Materials: A Survey Abstract: Natural fiber-reinforced polymer-based composites are increasingly used in modern society due to their numerous benefits for uses in mechanical engineering. Polymer-based composite materials are widely employed in civil construction, automotive, aerospace, and many other industries due to their many benefits. Natural fibers can be used to create new, highperformance polymer materials because they are affordable, environmentally friendly, renewable, and partially and fully biodegradable. Examples of these fibers include EGR Glass R Glass, Carbon fiber, and S Glass, as well as kenaf, pineapple, sugarcane, hemp, oil palm, flax, and leaf. The purpose of this study is to explore the use of natural fibers and composites in the production of airplane wings, including mechanical characteristics, applications, and potential as well as problems and future demand for natural composite materials for engineering uses. A good 50% of the airspace's components are natural composites. Because natural composites have the ability to lower aircraft weight, they are currently being used to construct helicopters, military fighter aircraft, small and large civil transport aircraft, cockpits, satellites, launch vehicles, and missiles. Rudder, spoilers, LG doors, keel beam, airbrakes, elevators, turbine engine fan blades, propellers, rear bulkhead, wing ribs, main wings, interior fixtures, etc. Composites made of natural fibers are attractive and promising. The use of natural fiber-based composite materials is growing daily due to their strength and integrity. The natural fiber is a renewable, environmentally beneficial, and biodegradable raw material. Both its mechanical and thermal insulation qualities are strong in natural fiber. However, the loading placed on the natural fiber and its youthful modulus determines its strength In addition to discussing the benefits of natural fibers over other materials, this paper provides a description of the several types of natural fiber, their physical and mechanical properties, and their advantages. Natural fiber ; Airplane ; Glass fiber ; Turbine blade ; Composite material ; Aerospace ; Composite number ; Bulkhead (partition) ; Fibre-reinforced plastic ; Kevlar ; Materials science ; Engineering ; Mechanical engineering ; Aerospace engineering ; Turbine Natural Fiber Reinforced Composites ; Mechanical Engineering and Vibrations Research ; Embedded Systems and FPGA Applications
Authors: F. F. Fondeur | Thomas L. White | Charles Coleman | David P. DiPrete | C. Nash | B.B. Looney
Source: Magnetic Resonance in Chemistry (article, 2023-03-27)
Field: Chemistry — Inorganic Chemistry

Proton nuclear magnetic resonance (1H NMR) of flammable organic chemicals in radioactive high‐level supernatant waste at the Savannah River Site (SRS) The Savannah River Site stores approximately 36 million gallons of radioactive and hazardous waste that contains approximately 245 million curies. The waste is sent through various chemical processes to reduce its volume and to separate various components. The facility plans to replace formic acid (a chemical used to reduce soluble mercury) with glycolic acid. Recycle solution with glycolate may flow back to the tank farm, where the glycolate can generate hydrogen gas by thermal and radiolytic mechanisms. The current analytical method for detecting glycolate (ion chromatography) in supernatant requires a large dilution to reduce interference from the nitrate anions. Hydrogen nuclear magnetic resonance is an analytical method that requires less sample dilution. It takes advantage of the CH<sub>2</sub> group in glycolate. Liquid samples were spiked with four different levels of glycolate to build a calibration line, as it is recommended in the standard addition method. The detection and quantitation limits determined were 1 and 5 ppm, respectively, for 32 scans, which is well below the process limit of 10 ppm. In one test, 800 scans of a supernatant spiked with 1 ppm glycolate resulted in a -CH<sub>2</sub> peak with a signal-to-noise ratio of 36. Chemistry ; Flammable liquid ; Radioactive waste ; Proton NMR ; Proton ; Savannah River Site ; Radiochemistry ; Nuclear magnetic resonance ; Environmental chemistry ; Nuclear chemistry ; Nuclear physics ; Organic chemistry Radioactive element chemistry and processing ; Radioactive contamination and transfer ; NMR spectroscopy and applications
Authors: Ravi Gautam | Takamasa Hirai | Abdulkareem Alasli | Hosei Nagano | Tadakatsu Ohkubo | Ken‐ichi Uchida | H. Sepehri‐Amin
Source: arXiv (Cornell University) (preprint, 2023-10-16)
Field: Materials Science — Materials Chemistry

Creation of flexible spin-caloritronic material with giant transverse thermoelectric conversion by nanostructure engineering Functional materials such as magnetic, thermoelectric, and battery materials have been revolutionized through nanostructure engineering. However, spin caloritronics, an advancing field based on spintronics and thermoelectrics with fundamental physics studies, has focused only on uniform materials without complex microstructures. Here, we show how nanostructure engineering enables transforming simple magnetic alloys into spin-caloritronic materials displaying significantly large transverse thermoelectric conversion properties. The anomalous Nernst effect (ANE), a promising transverse thermoelectric phenomenon for energy harvesting and heat sensing, has been challenging to utilize due to the scarcity of materials with large anomalous Nernst coefficients. We demonstrate a remarkable improvement in the anomalous Nernst coefficients in flexible Fe-based amorphous materials through nanostructural engineering, without altering their composition. This surpasses all reported amorphous alloys and is comparable to single crystals showing large ANE. The enhancement is attributed to Cu nano-clustering, facilitating efficient transverse thermoelectric conversion. This discovery advances the materials science of spin caloritronics, opening new avenues for designing high-performance transverse thermoelectric devices for practical applications. Nernst effect ; Thermoelectric effect ; Thermoelectric materials ; Materials science ; Nanostructure ; Amorphous solid ; Nernst equation ; Condensed matter physics ; Nanotechnology ; Supercapacitor ; Spintronics ; Engineering physics ; Ferromagnetism ; Physics ; Thermodynamics ; Chemistry ; Electrode ; Electrochemistry Advanced Thermoelectric Materials and Devices ; Electrocatalysts for Energy Conversion ; Advanced Memory and Neural Computing
Authors: Shaymaa M.F
Source: Tikrit Journal of Pure Science (article, 2023-02-03)
Field: Materials Science — Ceramics and Composites

Reinforcing a metal-based composite with a percentage of MgO particale to improve some of its properties and its relationship to conventional heat treatment This research involved the manufacture of three compounds using powdered metallurgy technology through the reinforcement of the AlNi with addition percentage (40%), (35%) and 30% (MgO) ceramic reinforce phase to compound of A , B and C respectively and thermally treated In the traditional way In order to study the effect of the MgO addition and heat treatment, the mechanical tests (Diametrical compressive strength and hardness) were conducted. In order to determine the possibility of using the models produced for the attenuation of β particles, The linear attenuation coefficient and half thickness were examined for all models, The mechanical properties and the linear attenuation coefficient of all compounds have been improved, It was observed that the effect of the chemical composition was greater on the properties under study. We obtained the value of the compressive compressive strength of C (29) MPa before the a heat treatment, while the same compound had the MPa ( 32) After the heat treatment, in case of change in the addition ratio, we obtained the highest values of the mechanical properties and the linear attenuation coefficient of C, (29) MPa, (39) and (19.6)cm-1 respectively., And the lowest value given to the thickness of half (0.035)cm compared with (0.078) given by the A compound with the lowest mechanical properties and the linear attenuation coefficient (26.5)Mpa, (34.5) and (8.8)cm-1respectively before thermal treatment. Materials science ; Attenuation ; Compressive strength ; Composite material ; Attenuation coefficient ; Ceramic ; Composite number ; Powder metallurgy ; Microstructure Advanced ceramic materials synthesis ; Surface Treatment and Coatings ; Aluminum Alloys Composites Properties
Authors: Chanaprom Cholsuk | Sujin Suwanna | Tobias Vogl
Source: arXiv (Cornell University) (preprint, 2023-05-29)
Field: Materials Science — Materials Chemistry

Comprehensive scheme for identifying defects in solid-state quantum systems A solid-state quantum emitter is one of the indispensable components for optical quantum technologies. Ideally, an emitter should have a compatible wavelength for efficient coupling to other components in a quantum network. It is therefore essential to understand fluorescent defects that lead to specific emitters. In this work, we employ density functional theory (DFT) to demonstrate the calculation of the complete optical fingerprints of quantum emitters in the two-dimensional material hexagonal boron nitride. These emitters are of great interest, yet many of them are still to be identified. Our results suggest that instead of comparing a single optical property, such as the commonly used zero-phonon line energy, multiple properties should be used when comparing theoretical simulations to the experiment. This way, the entire electronic structure can be predicted and quantum emitters can be designed and tailored. Moreover, we apply this approach to predict the suitability for using the emitters in specific quantum applications, demonstrating through the examples of the Al$_{\text{N}}$ and P$_{\text{N}}$V$_{\text{B}}$ defects. We therefore combine and apply DFT calculations to identify quantum emitters in solid-state crystals with a lower risk of misassignments as well as a way to design and tailor optical quantum systems. This consequently serves as a recipe for classification and the generation of universal solid-state quantum emitter systems in future hybrid quantum networks. Quantum ; Quantum network ; Common emitter ; Quantum technology ; Quantum state ; Computer science ; Optoelectronics ; Materials science ; Physics ; Quantum information ; Open quantum system ; Quantum mechanics Diamond and Carbon-based Materials Research ; Boron and Carbon Nanomaterials Research ; Graphene research and applications