jablonkagroup/rise_ai_scientists huggingface dataset:
Authors: Ganesan Nalini | Natesan Jayachandramani | R. Suresh | Thirumurugan Prakasam | V. Thanikachalam | G. Manikandan | D. Sankari
Source: European Journal of Chemistry (article, 2019-03-31)
Field: Materials Science — Materials Chemistry

Synthesis, characterization and thermal decomposition of ethyl-2’-amino-5’-cyano-6’-(1H-indole-3yl)-2-oxospiro[indoline-3,4’-pyran]-3’-carboxylate under non‐isothermal condition in nitrogen atmosphere A new compound, spiro-oxindole derivative compound namely ethyl-2ʹ-amino-5ʹ-cyano-6ʹ-(1H-indole-3yl)-2-oxospiro[indoline-3,4ʹ-pyran]-3ʹ-carboxylate (EACIOIPC) has been synthesized and characterized by microanalysis, FT-IR, mass spectrum and NMR (1H and 13C) techniques. The thermal decomposition of the compound was studied by thermogravimetric analysis under dynamic nitrogen atmosphere at different heating rates of 10, 15, 20 and 30 K/min. The kinetic parameters were calculated using model-free (Friedman’s, Kissinger-Akahira-Sunose (KAS) and Flynn-Wall-Ozawa (FWO) methods) and model-fitting (Coats and Redfern (CR)) methods. The decomposition process of EACIOIPC followed a single step mechanism as evidenced from the data. Existence of compensation effect is noticed for the decomposition of EACIOIPC. Invariant kinetic parameters are consistent with the average values obtained by Friedman and KAS in conversional methods. Chemistry ; Thermal decomposition ; Indoline ; Thermogravimetric analysis ; Pyran ; Carboxylate ; Decomposition ; Nitrogen ; Indole test ; Chemical process of decomposition ; Proton NMR ; Stereochemistry ; Organic chemistry Thermal and Kinetic Analysis ; Chemical Thermodynamics and Molecular Structure ; Energetic Materials and Combustion
Authors: Israa A. Al.Joboury | Shahlaa E. Ebrahime
Source: Association of Arab Universities Journal of Engineering Sciences (article, 2019-08-31)
Field: Chemistry — Analytical Chemistry

Biosorption of Cationic Dyes onto Cork Stopper Particles In this study, cork stopper particles were used as a low cost biosorbent to remove the cationic dyes (Methylene blue (MB), Malachite green (MG), and Methyl violet (MV)) from simulated wastewater. Batch sorption experiments of components were conducted as a function of pH, sorbent dosages, contact time, agitation speed, and particle size to optimize the best conditions for maximum removal efficiencies of dyes. The experimental data fitted slightly best to the Langmuir isotherm model than to Freundlich and Temkin isotherm model. The experimental data proved that the adsorption kinetic of MB, MG, and MV could be described by a pseudo-second order model. The results indicate that cork adsorbs dyes efficiently and could be employed as a low-cost alternative in wastewater treatment for the removal of cationic dyes. Cork ; Freundlich equation ; Cationic polymerization ; Malachite green ; Biosorption ; Sorption ; Methylene blue ; Langmuir ; Chemistry ; Sorbent ; Wastewater ; Adsorption ; Methyl violet ; Nuclear chemistry ; Chromatography ; Pulp and paper industry ; Environmental engineering ; Organic chemistry ; Environmental science Dye analysis and toxicity
Authors: Poklonski Nikolai | Dzeraviaha Aliaksandr | Vyrko Sergey | Kavaleu Aliaksandr
Source: Zenodo (CERN European Organization for Nuclear Research) (article, 2019-12-03)
Field: Materials Science — Surfaces, Coatings and Films

Migration of electrons via triple-charged defects of crystal matrix The study of semiconductor materials with point radiation defects of the crystal structure in three charge states (−1), (0), (+1) is important for determining the conditions of their radiation resistance under the influence of gamma rays, fast electrons, etc. Such defects are self-sufficient to ensure electrical neutrality of the materal under conditions of ionization equilibrium, that issue determines the radiation resistance of materials. In silicon and diamond crystals, such irradiation-induced defects during their accumulation stabilize the Fermi level in the vicinity of one third of the band gap from the top of the valence band. The purpose of the work is an analytical description of the stationary hopping electron transfer in a semiconductor, taking into account the joint migration of both the single electrons and the pairs of electrons over these triple-charged defects. A crystalline semiconductor is considered as a matrix containing immobile point defects of one sort in the prevailing concentration. For the first time in the drift-diffusion approximation, a phenomenological theory is constructed of coexisting migration of both the single electrons (transitions from the charge state −(1) to state (0) and from the state (0) to state +(0)), and the electron pairs (transitions from the state −(1) to state +(1)) by means of their hopping between such defects when an external stationary electric field is applied to the semi-conductor. In the linear approximation, analytical expressions are obtained for the screening length of a static electric field and the length of the hopping diffusion of electrons migrating via such defects. It is shown that the additional contribution of the hopping transport of electron pairs leads to a decrease in the screening length and also changes the diffusion length. Electron ; Crystal (programming language) ; Matrix (chemical analysis) ; Materials science ; Physics ; Computer science ; Nuclear physics ; Composite material Electron and X-Ray Spectroscopy Techniques
Authors: Matthew J. Whitley
Source: Carolina Digital Repository (University of North Carolina at Chapel Hill) (article, 2019-08-12)
Field: Chemistry — Spectroscopy

A Nuclear Magnetic Resonance Investigation of the Role of Structure and Dynamics in the Function of Chymotrypsin Inhibitor 2 The concept of proteins as static folded three-dimensional objects has yielded to the more sophisticated idea that proteins are better understood as dynamic entities constantly fluctuating about an average conformation rather than being restricted to any single conformation. With the knowledge that proteins sample many different conformational substates comes the question of whether the intrinsic conformational dynamics plays a role in protein function. The work presented in this dissertation begins to explore this question through the study of two model systems. The effects of subtle hydrophobic core mutations on the structure and internal dynamics of the nonallosteric protein chymotrypsin inhibitor 2 (CI2) were characterized using advanced nuclear magnetic resonance methodologies. These experiments revealed that the dynamics of methyl-bearing side chains respond globally and uniformly to hydrophobic core mutations without apparent regard for the position or chemical nature of the mutation; this is a clear example of long range intraprotein communication, a general property that forms the basis of the more complex phenomenon of allostery. Furthermore, the global increase in side-chain flexibility upon mutation takes place without concomitant structural perturbations. Functional assays of these mutants, however, revealed only subtle changes in inhibitory ability, and thus it appears that CI2 is not evolutionarily optimized to harness internal dynamics to modulate function despite its ability to sense perturbations through altered dynamics. The second model system studied is chemotaxis protein Y (CheY), the response regulator domain of the bacterial chemotaxis pathway. CheY is an allosteric protein, and this work reports a characterization of the dynamics involved in phosphorylation-based allosteric activation. The initial results indicate that the classic framework for understanding CheY allostery is too rigid in its definition of distinct inactive and active conformational states. Many of the key residues used to delineate the allosteric state of CheY are dynamic on multiple time scales, thus indicating that they sample numerous conformations and precluding the definition of a sole inactive or active conformation. The results of this work will be useful as a framework for analysis of larger, more complex proteins of biomedical relevance as our theoretical understanding of and experimental capabilities for studying protein dynamics continue to increase. Dynamics (music) ; Nuclear magnetic resonance ; Function (biology) ; Chymotrypsin ; Physics ; Chemistry ; Enzyme ; Biology ; Cell biology Analytical Chemistry and Chromatography ; thermodynamics and calorimetric analyses ; Viral Infectious Diseases and Gene Expression in Insects
Authors: 振英 王
Source: Kyushu University Institutional Repository (QIR) (Kyushu University) (article, 2019-08-31)
Field: Materials Science — Materials Chemistry

Mechanisms of Vapor Absorption into Hygroscopic Liquid Desiccant Droplets Lastly, I want to express my sincere love and gratitude to my family, my grandma, my mom and dad, and my little sister.They are my power sources.Due Desiccant ; Absorption (acoustics) ; Materials science ; Liquid desiccant ; Water vapor ; Chemical engineering ; Chemistry ; Composite material ; Organic chemistry ; Engineering Catalytic Processes in Materials Science ; Aerogels and thermal insulation
Authors: H.B. Kruthi | H. Shreya | Ch. Mahendra | Ravi Kiran | Archna Narula
Source: Asian Journal of Chemistry (article, 2019-07-31)
Field: Chemistry — Analytical Chemistry

Removal of Methylene Blue Dye Using Saw Palmetto Fruit (Serenoa repens) Waste The feasibility of saw palmetto fruit (Serenoa repens) waste as a low-cost bio-sorbent for treating methylene blue dye from synthetic textile effluent was evaluated. Two different types viz., untreated and alkaline treated saw palmetto fruit waste was tested to immobilize methylene blue dye from the synthetic effluent solution. Out of these two, the only alkaline treated saw palmetto fruit waste was found suitable for the removal of methylene blue from aqueous streams. With the untreated saw palmetto fruit waste, the sorption of dye increased with time and after reaching equilibrium, back diffusion of the sorbed dye was observed. Equilibrium sorption and kinetic studies were performed with alkaline treated saw palmetto fruit waste and the parameters affecting the sorption process such as initial dye concentration, adsorbent dose, equilibrium time and temperature were analyzed. The kinetic data generated obeyed pseudo-second-order kinetics. The investigated removal capacity of the saw palmetto fruit waste for the methylene blue dye was comparable with the available sorbents. Sorption ; Methylene blue ; Chemistry ; Effluent ; Sorbent ; Dyeing ; Nuclear chemistry ; Wastewater ; Pulp and paper industry ; Adsorption ; Waste management ; Organic chemistry ; Photocatalysis Dye analysis and toxicity ; Adsorption and biosorption for pollutant removal ; Water Quality Monitoring and Analysis
Authors: Axel Stenquist
Source: Lund University Publications Student Papers (Lund University) (article, 2019-01-01)
Field: Materials Science — Materials Chemistry

Investigation of thermal conductivity in thin graphite films through time-resolved X-ray diffraction Knowledge about thermal properties of nanoscale graphite is essential in order to realize the many promising applications of carbon based nanomaterials. This thesis reports how samples of thin graphite films on nickel substrates were investigated using time-resolved X-ray diffraction (TRXD) at the FemtoMAX beamline at the MAX IV facility. Through these investigations the thermal conductivity of the thin graphite films were determined by modeling the system using a one dimensional heat-diffusion model which was fitted to the data. Through investigation of the dynamics in the solid, it was determined that the thermal conductivity of graphite decreases with thinner graphite films as well as increased deposited energy. Graphite ; Materials science ; Thermal conductivity ; Thin film ; Diffraction ; Thermal diffusivity ; Beamline ; Analytical Chemistry (journal) ; Composite material ; Nanotechnology ; Optics ; Chemistry ; Thermodynamics ; Organic chemistry ; Physics ; Beam (structure) Thermal properties of materials ; Graphite, nuclear technology, radiation studies ; Graphene research and applications
Authors: J. Fliegans
Source: SPIRE - Sciences Po Institutional REpository (article, 2019-12-16)
Field: Materials Science — Electronic, Optical and Magnetic Materials

Coercitivité des aimants permanents Nd-Fe-B frittés - Approches expérimentales et numériques Les aimants permanents Nd-Fe-B sont actuellement les plus puissants du marché. Ils sont indispensables pour des applications telles que les moteurs des véhicules électriques ou les générateurs des éoliennes. Leurs propriétés exceptionnelles viennent des propriétés magnétiques intrinsèques de la phase Nd2Fe14B et de leur microstructure. Cependant, les machines électriques fonctionnent entre 120 et 180°C et les propriétés magnétiques extrinsèques telles que la coercitivité et la rémanence diminuent avec la température. Un moyen d’améliorer la coercitivité des aimants frittés Nd-Fe-B est la substitution du Nd par des terres rares lourdes comme le Dy, afin d’augmenter l’anisotropie magnétocristalline. Néanmoins, le Dy est un matériau critique et un objectif majeur de la recherche est actuellement de développer des aimants possédant d’excellentes propriétés magnétiques extrinsèques et contenant peu de Dy. Cela nécessite une meilleure compréhension du lien entre microstructure et coercitivité. Dans les aimants frittés Nd-Fe-B, un des points-clés est le contrôle de la taille de grain et de la répartition des phases secondaires aux joints de grains de façon à limiter la nucléation du retournement de l’aimantation et à garantir un bon découplage magnétique des grains. La première partie de la thèse est une étude comparative des caractérisations magnétiques en circuit ouvert et fermé réalisées sur des aimants frittés Nd-Fe-B. Les différences de coercitivité observées sont expliquées par les phénomènes de viscosité magnétique et d’effets de champ démagnétisant. La deuxième partie traite du procédé de diffusion aux joints de grains appliqué aux aimants frittés Nd-Fe-B et utilisant des alliages Dy-Co. Des caractérisations microstructurales ont été réalisées en complément de mesures magnétiques afin de déterminer les profils de diffusion et de coercitivité, et ainsi d’établir le lien entre les variations locales de composition chimique et le champ coercitif. De plus, des simulations micromagnétiques ont permis de décrire le retournement de l’aimantation à l’échelle nanométrique dans un modèle simplifié cœur-coquille. Enfin, la dernière partie de la thèse constitue une discussion sur la coercitivité des aimants diffusés au Dy-Co (à gradient de champ coercitif) à l’aide d’un modèle de diffusion et de simulations sur un modèle polycristallin. Physics ; Humanities ; Chemistry ; Art Magnetic Properties of Alloys ; Magnetic Properties and Applications ; Electromagnetic Launch and Propulsion Technology
Authors: Emmanuel Y. Medina | Elson Magalhães Toledo | Bernardo Martins Rocha
Source: Mecánica Computacional (Asociación Argentina de Mecánica Computacional) (article, 2019-11-21)
Field: Materials Science — Materials Chemistry

Adaptivite Schemes for FEM Approximation of the Higher-Order Generalized Cahn-Hilliard Equations The Cahn-Hilliard equation was introduced to model the phase separation in two-component alloys. This is one of the mathematical models most used to describe tumor growth through the evolution of healthy, cancerous and dead cells. In this work we present a numerical study of this equation by introducing higher-order derivatives with a nonlinear source term. Our objective is to solve the higher-order anisotropic problem with locally refined meshes in space using the finite element method for the generalized Cahn-Hilliard model. A phenomenological model that can describe the growth of a cancerous tumor will be treated. Numerical simulations are presented to illustrate the effects of higher-order terms on anisotropy and studies with space adaptivity strategy are also presented indicating its computational efficiency when compared to fixed meshes, especially in the case of anisotropic problems. Cahn–Hilliard equation ; Polygon mesh ; Finite element method ; Anisotropy ; Applied mathematics ; Space (punctuation) ; Mathematics ; Nonlinear system ; Term (time) ; Work (physics) ; Component (thermodynamics) ; Order (exchange) ; Mathematical analysis ; Mathematical optimization ; Partial differential equation ; Computer science ; Physics ; Geometry Solidification and crystal growth phenomena ; Aluminum Alloy Microstructure Properties ; Advanced Mathematical Modeling in Engineering
Authors: Nadeau Eric | Metzger Donald
Source: NCSU Libraries Repository (North Carolina State University Libraries) (article, 2019-08-04)
Field: Materials Science — Materials Chemistry

Diffusion Coefficient Modelling in Zr 2.5%Nb FOR USE IN PROBABILISTIC ROLLED JOINT DEUTERIUM UPTAKE ASSESSMENTS OF CANDU REACTORS Diffusion ; Deuterium ; Probabilistic logic ; Joint (building) ; Nuclear engineering ; Materials science ; Nuclear physics ; Radiochemistry ; Thermodynamics ; Chemistry ; Engineering ; Physics ; Mathematics ; Statistics Nuclear Materials and Properties ; Nuclear reactor physics and engineering ; Fusion materials and technologies
Authors: О. М. Мельниченко | Н. В. Сторожук | T. V. Zaporozhets | Andriy Gusak
Source: Cherkasy University Bulletin Physical and Mathematical Sciences (article, 2019-01-01)
Field: Materials Science — General Materials Science

MODELING OF THE KINETICS OF THE ALLOYS DECOMPOSITION AND HOMOGENIZATION BY THE MEAN- FIELD METHOD Hd МОДЕЛЮВАННЯ КІНЕТИКИ РОЗПАДУ ТА ГОМОГЕНІЗАЦІЇ СПЛАВІВ МЕТОДОМ Homogenization (climate) ; Kinetics ; Decomposition ; Materials science ; Field (mathematics) ; Thermodynamics ; Mathematics ; Chemistry ; Physics ; Classical mechanics ; Pure mathematics Material Properties and Applications ; Advancements in Materials Engineering
Authors: Juarez‐Perez Emilio J. | Qi Yabing
Source: Institutional Repositories DataBase (IRDB) (article, 2019-05-20)
Field: Materials Science — Materials Chemistry

Determination of Carrier Diffusion Length Using Transient Electron Photoemission Microscopy in the GaAs/InSe Heterojunction Carrier diffusion length and lifetime parameters for electron transport at nanoscale semiconductor slabs have been fitted using a 1D model and the decay data extracted from transient photoemission electron microscopy. Meanwhile, a conventional photoluminescence quenching measurement needs two separate samples with an active material between blocking and quenching layers to characterize the carrier transport properties. In this work, only one few-layer monocrystalline sample of gamma-InSe containing different thicknesses of active material is used to obtain a common diffusion coefficient consistent with previously reported values for vertical carrier diffusion in layered InSe. Diffusion ; Quenching (fluorescence) ; Photoluminescence ; Heterojunction ; Monocrystalline silicon ; Carrier lifetime ; Semiconductor ; Transient (computer programming) ; Analytical Chemistry (journal) Solid-state spectroscopy and crystallography ; Semiconductor materials and interfaces ; Semiconductor Quantum Structures and Devices
Authors: Šebojka Komorsky‐Lovrić | Milivoj Lovrić
Source: Bulgarian Chemical Communications (article, 2019-01-01)
Field: Chemistry — Electrochemistry

Theory of staircase cyclic voltammetry of two electrode reactions coupled by a chemical reaction Two reversible electrode reactions that are connected by either reversible or totally irreversible chemical reactions are theoretically analysed by staircase cyclic voltammetry. The dependence of peak potentials on the thermodynamic and kinetic parameters is calculated. If the mechanism is permanently in equilibrium, the stability constant of the reversible chemical reaction can be determined. Furthermore, the critical kinetic parameter is determined and its application to the measurement of the forward rate constant of the chemical reaction is demonstrated. Also, the influence of the kinetics of electrode reactions is discussed. Keywords: ECE mechanism; Cyclic voltammetry; Theory Cyclic voltammetry ; Reaction rate constant ; Chemistry ; Electrode ; Chemical reaction ; Reversible reaction ; Kinetic energy ; Voltammetry ; Reaction mechanism ; Chemical stability ; Thermodynamics ; Chemical kinetics ; Kinetics ; Reaction rate ; Physical chemistry ; Electrochemistry ; Organic chemistry ; Catalysis ; Physics ; Classical mechanics Electrochemical Analysis and Applications ; Electrochemical sensors and biosensors ; Conducting polymers and applications
Authors: Jun Wang | Ehssan Nazockdast | Alex H. Barnett
Source: arXiv (Cornell University) (preprint, 2019-12-10)
Field: Chemistry — Physical and Theoretical Chemistry

An integral equation method for the simulation of doubly-periodic suspensions of rigid bodies in a shearing viscous flow With rheology applications in mind, we present a fast solver for the time-dependent effective viscosity of an infinite lattice containing one or more neutrally buoyant smooth rigid particles per unit cell, in a two-dimensional Stokes fluid with given shear rate. At each time, the mobility problem is reformulated as a 2nd-kind boundary integral equation, then discretized to spectral accuracy by the Nystrom method and solved iteratively, giving typically 10 digits of accuracy. Its solution controls the evolution of particle locations and angles in a first-order system of ordinary differential equations. The formulation is placed on a rigorous footing by defining a generalized periodic Green's function for the skew lattice. Numerically, the periodized integral operator is split into a near image sum|applied in linear time via the fast multipole method|plus a correction field solved cheaply via proxy Stokeslets. We use barycentric quadratures to evaluate particle interactions and velocity fields accurately, even at distances much closer than the node spacing. Using first-order time-stepping we simulate, eg, 25 ellipses per unit cell to 3-digit accuracy on a desktop in 1 hour per shear time. Our examples show equilibration at long times, force chains, and two types of blow-ups (jamming) whose power laws match lubrication theory asymptotics. Stokes flow ; Mathematical analysis ; Discretization ; Mathematics ; Integral equation ; Physics ; Classical mechanics ; Flow (mathematics) ; Geometry Electrostatics and Colloid Interactions ; Material Dynamics and Properties ; Microfluidic and Bio-sensing Technologies