jablonkagroup/rise_ai_scientists huggingface dataset:
Authors: Wenqin Shi | Mirjam Theelen | A. Illiberi | Nicolas Barreau | Stefan J. van der Sar | Maik Butterling | H. Schut | Werner Egger | Marcel Dickmann | Christoph Hugenschmidt | Miro Zeman | E. Brück | S.W.H. Eijt
Source: Physical Review Materials (article, 2018-10-15)
Field: Materials Science — Materials Chemistry

Evolution and role of vacancy clusters at grain boundaries of ZnO:Al during accelerated degradation of <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mrow><mml:mi>Cu</mml:mi><mml:mrow><mml:mo>(</mml:mo><mml:mrow><mml:mi>In</mml:mi><mml:mo>,</mml:mo><mml:mi>Ga</mml:mi></mml:mrow><mml:mo>)</mml:mo></mml:mrow><mml:mi mathvariant="normal">S</mml:mi><mml:msub><mml:mi mathvariant="normal">e</mml:mi><mml:mn>2</mml:mn></mml:msub></mml:mrow></mml:math> solar cells revealed by positron annihilation Positron annihilation lifetime spectroscopy (PALS) and Doppler broadening positron annihilation spectroscopy (DB-PAS) depth profiling demonstrate pronounced growth of vacancy clusters at the grain boundaries of as-deposited Al-doped ZnO films deposited as transparent conductive oxide (TCO) on $\mathrm{Cu}(\mathrm{In},\mathrm{Ga})\mathrm{S}{\mathrm{e}}_{2}$ (CIGS) solar cells upon accelerated degradation at $85{\phantom{\rule{0.16em}{0ex}}}^{\ensuremath{\circ}}\mathrm{C}/85%$ relative humidity. Quantitative fractions of positrons trapped either in the vacancy clusters at the grain boundaries or in Zn monovacancies inside the grains of ZnO:Al were obtained by detailed analysis of the PALS data using a positron trapping model. The time and depth dependence of the positron Doppler depth profiles can be accurately described using a planar diffusion model, with an extracted diffusion coefficient of $35\phantom{\rule{0.28em}{0ex}}\mathrm{n}{\mathrm{m}}^{2}/\mathrm{hour}$ characteristic for in-diffusion of molecules such as ${\mathrm{H}}_{2}\mathrm{O}$ and $\mathrm{C}{\mathrm{O}}_{2}$ into ZnO:Al TCO films via the grain boundaries, where they react with the ZnO:Al. This leads to increased open volume at the grain boundaries that imposes additional transport barriers and may lead to charge carrier trapping and nonradiative recombination. Simultaneously, a pronounced increase in series resistance and a strong reduction in efficiency of the ZnO:Al capped CIGS solar cells is observed on a remarkably similar timescale. This strongly indicates that these atomic-scale processes of molecular in-diffusion and creation of open volume at the grain boundaries play a key role in the degradation of the solar cells.PhySH: Solar Cells, Positron Annihilation Spectroscopy, Grain Boundaries, Vacancies, Thin Films, Diffusion, Electrical Properties, Solid State Chemistry, Optoelectronics Grain boundary ; Materials science ; Annihilation ; Vacancy defect ; Positron annihilation spectroscopy ; Diffusion ; Analytical Chemistry (journal) ; Crystallography ; Positron ; Positron annihilation ; Condensed matter physics ; Physics ; Microstructure ; Thermodynamics ; Particle physics ; Nuclear physics ; Metallurgy ; Electron ; Chemistry ZnO doping and properties ; Muon and positron interactions and applications ; Semiconductor materials and interfaces
Authors: Wen Zheng | Philip G. Whitten | Geoffrey M. Spinks
Source: Multifunctional Materials (article, 2018-09-24)
Field: Materials Science — Polymers and Plastics

Polypyrrole actuators: the effects of polymer thickness and voltage scan rate on fractional charging and isotonic actuation strain © 2018 IOP Publishing Ltd. For conducting polymer actuators to be practically useful, they need to be able to generate large forces and displacements and respond quickly. The simplest way to generate larger forces is to produce thicker actuators, but this approach has a negative impact on the response time. The effects of polypyrrole film thickness and voltage scan rate on the electrochemical actuation strain rate are investigated in this study. The rate of oxidative charging is shown to follow a standard Fickian diffusion model suggesting that the migration of ions into the polymer from the electrolyte is the dominant rate-determining mechanism. The migration rate is slow with full oxidation requiring several minutes for film thicknesses of just 10 μm. The free strains generated were found to be directly proportional to the oxidative charge passed. The isotonic actuation strains were additionally reduced by increasing applied stress and this effect was attributed to the increase in Young's modulus that occurs during polypyrrole oxidation. Asimple model is presented that predicts the change in modulus during oxidation and gives reasonable estimates of the isotonic actuation for PPy actuators of different thickness and when subjected to different stresses. Polypyrrole ; Materials science ; Electrolyte ; Actuator ; Composite material ; Voltage ; Horizontal scan rate ; Diffusion ; Isotonic ; Modulus ; Polymer ; Stress (linguistics) ; Deformation (meteorology) ; Conductive polymer ; Electrochemistry ; Chemistry ; Electrode ; Thermodynamics ; Electrical engineering ; Polymerization Conducting polymers and applications ; Advanced Sensor and Energy Harvesting Materials ; Analytical Chemistry and Sensors
Authors: F. Houhoune | Sihem Khemaissia | Djamel Nibou | Salah Chegrouche | S. Menacer
Source: AIP conference proceedings (article, 2018-01-01)
Field: Chemistry — Inorganic Chemistry

Kinetic study and sorption mechanism of uranium (VI) onto NaY zeolite Radioactive Uranium (VI) was removed by adsorption on NaY zeolite. The synthesized NaY zeolite sorbent was characterized with several techniques: X-ray diffraction XRD, scanning electronic microscopy MEB and Infrared spectroscopy measurements FTIR. Textural properties were determined by N2 adsorption isotherm. Batch adsorption experiments were performed to study the adsorption of uranium (VI) from aqueous solutions on NaY zeolite material. Operating variables studied include solution pH, contact time and temperature. Equilibrium data were analyzed by the Langmuir, Freundlich and Dubinin-Radushkevich models. The equilibrium data were best represented by the Langmuir isotherm model. Sorption kinetic data were fitted using pseudo first order, pseudo second order models and Intraparticule diffusion model. The experimental data fitted very well the pseudo second order model. The process mechanism was found to be complex, consisting of both mass transfer and intraparticle diffusion. The thermodynamic parameters such as standard free energy ΔG0, standard enthalpy ΔH0 and standard entropy ΔS0 have been determined which indicates a spontaneous exothermic adsorption process. Freundlich equation ; Zeolite ; Adsorption ; Sorption ; Langmuir ; Enthalpy ; Standard molar entropy ; Materials science ; Langmuir adsorption model ; Aqueous solution ; Uranium ; Gibbs free energy ; Thermodynamics ; Chemistry ; Physical chemistry ; Organic chemistry ; Catalysis ; Metallurgy Radioactive element chemistry and processing ; Chemical Synthesis and Characterization ; Adsorption and biosorption for pollutant removal
Authors: M.J. Simmonds | J.H. Yu | Yue Wang | M.J. Baldwin | R.P. Doerner | George Tynan
Source: Journal of Nuclear Materials (article, 2018-06-04)
Field: Materials Science — Materials Chemistry

Expanding the capability of reaction-diffusion codes using pseudo traps and temperature partitioning: Applied to hydrogen uptake and release from tungsten Trapping ; Trap (plumbing) ; Tungsten ; Thermal desorption ; Range (aeronautics) ; Desorption ; Diffusion ; Atmospheric temperature range ; Chemistry ; Activation energy ; Atomic physics ; Thermal ; Hydrogen ; Chemical physics ; Analytical Chemistry (journal) ; Thermodynamics ; Materials science ; Physics ; Physical chemistry ; Adsorption Fusion materials and technologies ; Nuclear Materials and Properties ; Semiconductor materials and devices
Authors: Ignacio Rojas-Rodríguez | Alberto Lara-Guevara | Mauricio Salazar-Sicacha | J. Mosquera | Minerva Robles-Agudo | Cristian Felipe Ramirez-Gutierrez | Mario E. Rodríguez‐García
Source: Materials Sciences and Applications (article, 2018-01-01)
Field: Materials Science — Materials Chemistry

The Influence of the Precipitation Heat Treatment Temperature on the Metallurgical, Microstructure, Thermal Properties, and Microhardness of an Alpha Brass Metals obtain optimum conditions of metallurgical and physical properties through a heat treatment. Brass is one of the copper alloys which has many applications in everyday life and in the industry. Brass is one of the copper alloys which has many applications in everyday life and the industry. In this work, the influence of the precipitation heat treatment temperature on the metallurgical microstructure, structure, thermal properties, and microhardness of an alpha brass is analyzed. Samples were heat treated by precipitation for 2 h at 300°C, 400°C, 500°C, 600°C, and 700°C. The best mechanical properties were found at 500°C of precipitation heat treatment temperature. Specimens were characterized by scanning electron microscopy, X-ray diffraction, Vickers microhardness, photothermal radiometry, and photoacoustic to study the thermal diffusivity and conductivity, as well as the heat capacity. The inverse of the full width at the half maximum analysis showed that the crystallinity decreased as the precipitation heat treatment temperature increased. Metallurgical microstructure and microhardness were correlated to the precipitation heat treatment temperatures to determine the effect on the metallurgical and mechanical properties, as well as the effect on the thermal properties of alpha brass. Brass ; Materials science ; Microstructure ; Indentation hardness ; Precipitation ; Metallurgy ; Scanning electron microscope ; Thermal diffusivity ; Copper ; Composite material ; Thermodynamics Metallurgy and Material Science ; Aluminum Alloy Microstructure Properties ; Additive Manufacturing Materials and Processes
Authors: М. Кеддам
Source: Acta Physica Polonica A (article, 2018-05-01)
Field: Materials Science — Materials Chemistry

A Diffusion Model for the Fe<sub>2</sub>B Layers Formed on a Ductile Cast Iron In this work, a diffusion model was applied to estimate the boron diffusion coefficients in the Fe2B layers on the ASTM A-536 ductile iron in the temperature range 1173-1273 K by the powder-pack boriding. The mass balance equation at the (Fe2B/substrate) interface was formulated considering the effect of boride incubation times. As a result, the value of activation energy for boron diffusion in the ductile iron was estimated and compared with the literature. To verify the validity of the present model, the experimental Fe2B layer thickness obtained at 1173 K for 10 h was compared to the predicted value. A good concordance was observed between the predicted value of Fe2B layer thickness and the experimental data. Boriding ; Materials science ; Diffusion ; Boron ; Boride ; Cast iron ; Activation energy ; Work (physics) ; Substrate (aquarium) ; Atmospheric temperature range ; Layer (electronics) ; Metallurgy ; Composite material ; Thermodynamics ; Physical chemistry ; Chemistry Metal Alloys Wear and Properties ; Powder Metallurgy Techniques and Materials ; Microstructure and Mechanical Properties of Steels
Authors: А. В. Сыроешкин | Т. В. Плетенева | E. V. Uspenskaya | O. V. Levitskaya | M. A. TRIBOT-LASPIERE | I. A. Zlatsky | Н. А. Ходорович | M. V. Nikifirova | S. A. Zaytseva
Source: International Journal of Applied Pharmaceutics (article, 2018-09-08)
Field: Chemistry — Spectroscopy

POLARIMETRIC RESEARCH OF PHARMACEUTICAL SUBSTANCES IN AQUEOUS SOLUTIONS WITH DIFFERENT WATER ISOTOPOLOGUES RATIO Objective: Methodology development for quality control of optically active pharmaceutical substances based on water isotopologues.Methods: Solutions of L-ascorbic acid, glucose, galactose and valine stereoisomers were prepared using deuterium depleted water (DDW-«light» water, D/H=4 ppm), natural deionized high-ohmic water (BD, D/H=140 ppm), heavy water (99.9% D2O). The optical rotation was observed using an automatic polarimeter Atago POL-1/2. The size distribution of giant heterogeneous clusters (GHC) of water was recorded by low angle laser light scattering (LALLS) method.Results: The infringement of Biot’s Law was found for solutions of ascorbic acid, expressed in the absence of a constant value of the specific optical rotation at a concentration of below 0.1%, depends on the D/H ratio. The inequality was established in absolute values of optical rotation for L-and D-isomers of valine in solutions with different ratios of hydrogen isotopologues. The mutarotation of glucose confirmed the first-order kinetics, and the activation energies were statistically distinguishable for BD and DDW. The mutarotation of the natural galactose D-isomer proceeded with a lower energy consumption compared to the L-isomer. In heavy water, the mutarotation of monosaccharides had different kinetic mechanisms. Polarimetric results correlated with the number and size of GHC, which confirmed the possibility of chiral solvent structures induction by optically active pharmaceutical substances.Conclusion: In the optically active pharmaceutical substances quality control there should be considered the contribution of induced chiral GHC of water to the optical rotation value that depends on the isotopic D/H ratio, the substance nature and the form of its existence at a given pH. Chemistry ; Mutarotation ; Specific rotation ; Aqueous solution ; Optical rotation ; Isotopologue ; Deuterium ; Analytical Chemistry (journal) ; Physical chemistry ; Stereochemistry ; Chromatography ; Organic chemistry ; Molecule ; Physics Molecular spectroscopy and chirality ; Analytical Chemistry and Chromatography ; Chemical Reactions and Isotopes
Authors: Eunyoung Jeong | Myung‐Ji Lee | Min-Seung Kang | Hoi‐Seon Lee
Source: Applied Biological Chemistry (article, 2018-05-15)
Field: Materials Science — Biomaterials

Antimicrobial agents of 4-methoxysalicylaldehyde isolated from Periploca sepium oil against foodborne bacteria: structure–activity relationship This study was designed to evaluate the antimicrobial activities of 4-methoxysalicylaldehyde isolated from Periploca sepium and its derivatives against six foodborne bacteria (Listeria monocytogenes, Salmonella typhimurium, Shigella flexneri, S. sonnei, Staphylococcus intermedius and S. aureus). Essential oil extracted from P. sepium roots exhibits strong antimicrobial activity against foodborne bacteria. The antimicrobial compound of P. sepium isolated by chromatographic techniques was identified as 4-methoxysalicylaldehyde. To compare the antimicrobial activities of 4-methoxysalicylaldehyde and its derivatives (4-hydroxysalicylaldehyde, salicylaldehyde, 3-methoxysalicylaldehyde, 5-methoxysalicylaldehyde, 3-methylsalicylaldehyde, and 5-methylsalicylaldehyde), the MIC test was performed. These activities were exhibited by 4-methoxysalicylaldehyde (MIC 30.1–67.3 μg/mL) followed by 4-hydroxysalicylaldehyde (MIC 41.1–61.5 μg/mL) and 4-methoxysalicylaldehyde (MIC 41.3–92.1 μg/mL) against all tested microorganisms. The results indicate that 4-methoxysalicylaldehyde and its derivatives represent natural antimicrobial alternatives. Antimicrobial ; Chemistry ; Shigella flexneri ; Staphylococcus intermedius ; Listeria monocytogenes ; Bacteria ; Microbiology ; Shigella sonnei ; Staphylococcus aureus ; Food science ; Salmonella ; Shigella ; Traditional medicine ; Staphylococcus ; Escherichia coli ; Biology ; Biochemistry ; Organic chemistry Phytochemistry and Bioactive Compounds ; Essential Oils and Antimicrobial Activity ; Morinda citrifolia extract uses
Authors: Zari Majidi Mohammadie | Kazem Parivar | Nasser Mahdavi SHahri | Masoud Fereidoni | Nasim Hayati Roodbari
Source: Brazilian Archives of Biology and Technology (article, 2018-01-08)
Field: Materials Science — Biomaterials

Decellularized Bovine Articular Cartilage Matrix Reinforced by Carboxylated-SWCNT for Tissue Engineering Application Nanotubes with their unique properties have diversified mechanical and biological applications. Due to similarity of dimensions with extracellular matrix (ECM) elements, these materials are used in designing scaffolds. In this research, Carboxylated Single-Wall Carbon Nanotubes in optimization of decellularized scaffold of bovine articular cartilage was used. At first, the articular cartilage was decellularized. Then the scaffolds were analyzed in: (i) decellularized scaffolds, and (ii) scaffolds plunged into homogenous suspension of nanotubes in distilled water, were smeared with Carboxylated-SWCNT. The tissue rings derived from the rabbit's ear were assembled with reinforced scaffolds and they were placed in a culture media for 15 days. The scaffolds in two groups and the assembled scaffolds underwent histologic and electron microscopy. Scanning electron microscopy showed that the structure of ECM of articular cartilage has been maintained well after decellularization. Fourier transform infrared analysis showed that the contents of ECM have not been changed under treatment process. Atomic force microscopy analysis showed the difference in surface topography and roughness of group (ii) scaffolds in comparison with group (i). Transmission electron microscopy studies showed the Carboxylated-SWCNT bond with the surface of decellularized scaffold and no penetration of these compounds into the scaffold. The porosity percentage with median rate of 91.04 in group (i) scaffolds did not have significant difference with group (ii) scaffolds. The electron microscopy observations confirmed migration and penetration of the blastema cells into the group (ii) assembled scaffolds. This research presents a technique for provision of nanocomposite scaffolds for cartilage engineering applications. Decellularization ; Scaffold ; Biomedical engineering ; Materials science ; Extracellular matrix ; Tissue engineering ; Cartilage ; Matrix (chemical analysis) ; Chemistry ; Nanotechnology ; Composite material ; Anatomy Electrospun Nanofibers in Biomedical Applications ; Tissue Engineering and Regenerative Medicine ; Bone Tissue Engineering Materials
Authors: Paul V. Bernhardt | Jessica K. Bilyj | Victor Brosius | Dmitry Chernyshov | Robert J. Deeth | Marco Foscato | Vidar R. Jensen | Nicole Mertes | Mark J. Riley | Karl W. Törnroos
Source: Chemistry - A European Journal (article, 2018-01-09)
Field: Materials Science — Electronic, Optical and Magnetic Materials

Spin Crossover in a Hexaamineiron(II) Complex: Experimental Confirmation of a Computational Prediction 2015, 55, 1844], offering the first experimental validation of a functional transition-metal complex predicted by such in silico molecular design methods. Additional quantum chemical calculations offer, together with the crystal structure analysis, insight into the role of spin-passive structural components. A thermodynamic analysis based on an Ising-like mean field model (Slichter-Drickammer approximation) provides estimates of the enthalpy, entropy and cooperativity of the crossover between the high and low spin states. Spin crossover ; Cooperativity ; Chemistry ; Spin states ; Ground state ; Ising model ; Spin transition ; Enthalpy ; Spin (aerodynamics) ; Condensed matter physics ; Thermodynamics ; Crystallography ; Physics ; Atomic physics Magnetism in coordination complexes ; Metal-Catalyzed Oxygenation Mechanisms ; Lanthanide and Transition Metal Complexes
Authors: Kyle M. Koss | Larry D. Unsworth
Source: Materials (article, 2018-08-27)
Field: Materials Science — Biomaterials

Towards Developing Bioresponsive, Self-Assembled Peptide Materials: Dynamic Morphology and Fractal Nature of Nanostructured Matrices (Arginine-alanine-aspartic acid-alanine)₄ ((RADA)₄) nanoscaffolds are excellent candidates for use as peptide delivery vehicles: they are relatively easy to synthesize with custom bio-functionality, and assemble in situ to allow a focal point of release. This enables (RADA)₄ to be utilized in multiple release strategies by embedding a variety of bioactive molecules in an all-in-one "construct". One novel strategy focuses on the local, on-demand release of peptides triggered via proteolysis of tethered peptide sequences. However, the spatial-temporal morphology of self-assembling nanoscaffolds may greatly influence the ability of enzymes to both diffuse into as well as actively cleave substrates. Fine structure and its impact on the overall effect on peptide release is poorly understood. In addition, fractal networks observed in nanoscaffolds are linked to the fractal nature of diffusion in these systems. Therefore, matrix morphology and fractal dimension of virgin (RADA)₄ and mixtures of (RADA)₄ and matrix metalloproteinase 2 (MMP-2) cleavable substrate modified (RADA)₄ were characterized over time. Sites of high (glycine-proline-glutamine-glycine+isoleucine-alanine-serine-glutamine (GPQG+IASQ), CP1) and low (glycine-proline-glutamine-glycine+proline-alanine-glycine-glutamine (GPQG+PAGQ), CP2) cleavage activity were chosen. Fine structure was visualized using transmission electron microscopy. After 2 h of incubation, nanofiber networks showed an established fractal nature; however, nanofibers continued to bundle in all cases as incubation times increased. It was observed that despite extensive nanofiber bundling after 24 h of incubation time, the CP1 and CP2 nanoscaffolds were susceptible to MMP-2 cleavage. The properties of these engineered nanoscaffolds characterized herein illustrate that they are an excellent candidate as an enzymatically initiated peptide delivery platform. Morphology (biology) ; Fractal ; Materials science ; Peptide ; Nanotechnology ; Polymer science ; Chemical engineering ; Chemistry ; Mathematics ; Engineering ; Mathematical analysis Supramolecular Self-Assembly in Materials ; Polydiacetylene-based materials and applications ; Diatoms and Algae Research
Authors: James Oreluk | Zhenyuan Liu | Arun Hegde | Wenyu Li | Andrew Packard | Michael Frenklach | Dmitry Yu. Zubarev
Source:  (article, 2018-09-05)
Field: Materials Science — Materials Chemistry

Diagnostics of Data-Driven Models: Uncertainty Quantification of PM7 Semi-Empirical Quantum Chemical Method. We report an evaluation of a semi-empirical quantum chemical method PM7 from the perspective of uncertainty quantification. Specifically, we apply Bound-to-Bound Data Collaboration, an uncertainty quantification framework, to characterize (a) variability of PM7 model parameter values consistent with the uncertainty in the training data and (b) uncertainty propagation from the training data to the model predictions. Experimental heats of formation of a homologous series of linear alkanes are used as the property of interest. The training data are chemically accurate, i.e., they have very low uncertainty by the standards of computational chemistry. The analysis does not find evidence of PM7 consistency with the entire data set considered as no single set of parameter values is found that captures the experimental uncertainties of all training data. A set of parameter values for PM7 was able to capture the training data within ±1 kcal/mol, but not to the smaller level of uncertainty in the reported data. Nevertheless, PM7 was found to be consistent for subsets of the training data. In such cases, uncertainty propagation from the chemically accurate training data to the predicted values preserves error within bounds of chemical accuracy if predictions are made for the molecules of comparable size. Otherwise, the error grows linearly with the relative size of the molecules. Consistency (knowledge bases) ; Propagation of uncertainty ; Experimental data ; Set (abstract data type) ; Data consistency ; Computer science ; Measurement uncertainty ; Series (stratigraphy) ; Data set ; Algorithm ; Statistical physics ; Mathematics ; Statistics ; Physics ; Artificial intelligence Machine Learning in Materials Science ; Computational Drug Discovery Methods ; Mass Spectrometry Techniques and Applications