jablonkagroup/rise_ai_scientists huggingface dataset:
Authors: Marianne S. Eikeland | HANS-KRISTIAN ALMOEN GRAVKLEV | Hui Huang | Vibeke Bredvold Karlsen | ANNE KATRINE SEM | TOMMY STOKKA | MORTEN AUGESTAD | Kjell‐Arne Solli
Source: WIT transactions on ecology and the environment (article, 2020-07-17)
Field: Materials Science — Biomaterials

OXYGEN DIFFUSION THROUGH POLYMER MEMBRANES UNDER NON-STEADY-STATE CONDITIONS Polymers are used as food packaging material to preserve the food and to increase the shelf life. Oxygen accelerates the growth of bacteria and other microorganisms and can reduce the durability of the food. By using polymers as a food packaging material, the decomposition and the amount of food waste can be reduced. It is therefore important to predict the diffusion rate of oxygen through the polymers when a certain type of polymer is used. The main goal of this article is to study the influence of temperature variations on the oxygen diffusion through a polymer material. Laboratory experiments are performed by measuring the concentration of oxygen in nitrogen filled polypropylene boxes under constant temperatures and with temperature variations over time. The experiments show that the oxygen diffusion increases with increasing temperature. An effect of changing the temperature is that the permeation rate in the polymer becomes higher when the polymer has first been exposed to a higher temperature. This is an important observation and has to be taken into account when food is exposed to different temperatures during transport and storage. A mathematical model is formulated to estimate the oxygen concentration in the boxes. The comparison between literature data, the model and the experimental results indicates that, although there is deviation between the data, the tendency of increase in oxygen concentration with time is the same. Oxygen ; Polymer ; Permeation ; Polypropylene ; Diffusion ; Decomposition ; Steady state (chemistry) ; Membrane ; Limiting oxygen concentration ; Fick's laws of diffusion ; Food packaging ; Materials science ; Chemistry ; Chemical engineering ; Thermodynamics ; Composite material ; Organic chemistry ; Food science Nanocomposite Films for Food Packaging ; Microplastics and Plastic Pollution ; Polymer Science and PVC
Authors: V. Barsukov | Volodymyr Khomenko | Oksana Chernysh
Source: Journal of Electrochemical Science and Engineering (article, 2020-02-01)
Field: Chemistry — Electrochemistry

On the processes of migration and diffusion in the systems with solid-state reagents This paper deals with peculiarities of diffusion and migration in electrochemical systems with solid-state reagents (ESSSR). Contradictions of the diffusion model are analyzed. It is the difference of applied potentials and the corresponding electric field strength in the bulk solid phase and at the interfaces which is the primary driving force of charge transfer in ESSSR. The time characteristic of diffusion processes is not comparable to the duration of electrode processes at charging/discharging of batteries and especially electrochemical capacitors. In many real systems involving ESSSR, the process of diffusion in solid phase is absent. Examples of charge transfer processes in ESSSR (nickel hydroxide electrode, sparingly soluble quinoid compounds, Li+ intercalation in graphite, etc.) are considered, and the processes are explained using the Grothuss, tunnel and other migration mechanisms. It is shown in this paper that the linear relationship between peak currents in voltammetric curves and the square root of potential scan rate cannot be presented as an ultimate support of the diffusion model, but as а more universal property of ESSSR. In this aspect, the efficient diffusion coefficient, Deff, could be at best discussed, not to distort the ideas of charge-transfer migration mechanisms in the ESSSR. Diffusion ; Reagent ; Electrochemistry ; Hydroxide ; Phase (matter) ; Charge (physics) ; Electrode ; Chemical physics ; Chemistry ; Materials science ; Thermodynamics ; Inorganic chemistry ; Physical chemistry ; Physics Electrochemical Analysis and Applications ; Conducting polymers and applications ; Transition Metal Oxide Nanomaterials
Authors: Piotr Polanowski | Andrzej Sikorski
Source: Frontiers in Physics (article, 2020-11-27)
Field: Materials Science — Materials Chemistry

The Concept of Cooperative Dynamics in Simulations of Soft Matter In this review we compiled recent advances concerning the cooperative motion in crowded soft matter systems. We tried to answer the question how to perform dynamic Monte Carlo simulations of dense macromolecular systems effectively. This problem is not simple due to the fact that the movement in such systems is strictly correlated which leads to cooperative phenomena. The influence of crowding was found interesting especially for two-dimensional cases, e.g., in membranes where the presence of macromolecules, proteins and cytoskeleton often changed the mean-square displacement as a function of the lag time and anomalous diffusion appeared. Simple models are frequently used to shed a light on molecular transport in biological systems. The emphasis was given to the Dynamic Lattice Liquid model. The latter model became a basis for a parallel algorithm that takes into account coincidences of elementary molecular motion attempts resulting in local cooperative structural transformations. The emphasis is put on influence of the model of molecular transport on the diffusion. The comparison to alternative approaches like single agent model was carried out. Statistical physics ; Macromolecular crowding ; Active matter ; Simple (philosophy) ; Soft matter ; Mean squared displacement ; Monte Carlo method ; Diffusion ; Computer science ; Molecular dynamics ; Physics ; Macromolecule ; Chemistry ; Mathematics ; Quantum mechanics Material Dynamics and Properties ; Spectroscopy and Quantum Chemical Studies ; Thermodynamic properties of mixtures
Authors: Dekui Zhan | Xinhai Zhao | Shaoxiong Xia | Peng Chen | Huandong Chen
Source: Science and Technology of Nuclear Installations (article, 2020-08-03)
Field: Materials Science — Materials Chemistry

Numerical Simulation and Validation for Early Core Degradation Phase under Severe Accidents Early core degradation determines the amount of hydrogen generated by cladding oxidation as well as the temperature, the mass, and the composition of corium that further relocates into the lower head of reactor pressure vessel (RPV), which is essential for the effectiveness analysis of in-vessel retention (IVR) and hydrogen recombiners. In this paper, the mechanisms of controlling phenomena in the early phase of core degradation are analysed at first. Then, numerical models adopted to calculate (1) core heating up, (2) cladding oxidation, (3) dissolution between molten zirconium and fuel pellets, and (4) formation of a molten pool in the core active section are presented. Compared with integral codes for severe accident analysis (such as MAAP and MELCOR), the models in this paper are established at the fuel pin level and the calculation is performed in 3D, which can capture the detail local phenomena during the core degradation and eliminate the average effect due to equivalent rings used in integral codes. In addition, most of the control equations in this paper are calculated by implicit schemes, which can improve the accuracy and stability of the calculation. In the simulation, the calculation oxidation is calculated by using the oxygen diffusion model, while the dissolution is calculated with Kim, Hayward, Hofmann, and IBRAE models to perform uncertainty analysis. For the validation, the cladding oxidation model is verified by Olander theoretical cases in the conditions of both steam-rich and steam-starved. The dissolution models are validated by the RIAR experiment. The code is overall verified by Phebus FPT0 on the integral phase of core early degradation. According to the simulation results, it can be inferred that the dissolution reaction between the molten zirconium and fuel pellets is the main reason for the melting of UO 2 at low temperature. In the case of starved steam, part of the fuel pellets can melt down even at 2248 K and relocate to the bottom of the core, which is much lower than the melting point of UO 2 (3113 K). Cladding (metalworking) ; Dissolution ; Nuclear engineering ; Pellets ; Materials science ; Degradation (telecommunications) ; Zirconium ; Hydrogen ; Mechanics ; Engineering ; Chemistry ; Metallurgy ; Physics ; Chemical engineering ; Composite material Nuclear Materials and Properties ; Nuclear reactor physics and engineering ; Thermodynamic and Structural Properties of Metals and Alloys
Authors: Stefano Brandani
Source: Adsorption (article, 2020-09-15)
Field: Chemistry — Physical and Theoretical Chemistry

Exact equivalence at cyclic steady state between isothermal diffusion and linear driving force models for linear adsorption systems Abstract To match the dynamics of a linear driving force model and the diffusion equation is of great practical importance in the design and optimization of adsorption separation processes. A frequency response analysis is applied to show that it is not possible to arrive at an equivalence based on a single parameter. Using this as the basis, a universal equivalence for the linear problem is constructed and closed form analytical expressions for the two parameters are derived for the sphere and slab geometries. The two parameters represent the increased effective mass transfer coefficient and a reduction in the active volume of the particle, both corresponding to the internal concentration profiles of the diffusion equation at cyclic steady state. Equivalence (formal languages) ; Isothermal process ; Diffusion ; Steady state (chemistry) ; Mathematics ; Slab ; Nonlinear system ; Mass transfer ; Diffusion equation ; Thermodynamics ; Mathematical analysis ; Applied mathematics ; Physics ; Chemistry ; Physical chemistry ; Engineering Electrostatics and Colloid Interactions ; Membrane Separation and Gas Transport ; Advanced Thermodynamics and Statistical Mechanics
Authors: Z. Tiouti | B. Azeddine | A. HELMAOUI
Source: Chalcogenide Letters (article, 2020-11-01)
Field: Materials Science — Surfaces, Coatings and Films

THE CONCENTRATION OF ELECTRON-HOLE PAIRS GENERATED BY THE INTERACTION OF ELECTRON WITH MATTER, CASE OF CdS USING MONTE CARLO SIMULATION In this study, we use a Monte Carlo Calculation code to simulate the stopping range and the concentration of electron-hole pairs generated of each point in the solid targets under a bombardment, those electrons and holes generating a low electrical power source for many specialized applications. The model has been tested for CdS structure, under a bombardment of one electron with energy 50 - 150 KeV. Monte Carlo method ; Electron ; Stopping power ; Atomic physics ; Range (aeronautics) ; Materials science ; Physics ; Computational physics ; Molecular physics ; Nuclear physics ; Ion Electron and X-Ray Spectroscopy Techniques
Authors: E. E. B. Campbell | Henry J. Chandler | Renald Schaub
Source: The European Physical Journal D (article, 2020-06-01)
Field: Chemistry — Organic Chemistry

Sublimation of Li@C60 Abstract Experiments that probe the fundamental properties of endohedral fullerenes often require the preparation of molecular beams or thin films of the neutral molecules. It is challenging to cleanly sublime this class of molecules without producing some thermal degradation. We report combined gas phase and scanning tunnelling microscopy studies that probe the thermal decay of commercial [Li + C 60 ]PF 6 - in a quartz ampoule and provide treatment conditions that will allow the sublimation of intact, neutral Li@C 60 accompanied by a well-characterised component of neutral C 60 . The decay of the material at appropriate temperatures can be modelled with the assumption of a second order decay process in the oven yielding Arrhenius parameters that can predict the ratio of Li@C 60 to C 60 in the sublimed material. Graphical abstract Sublimation (psychology) ; Fullerene ; Materials science ; Molecule ; Ampoule ; Thermal ; Arrhenius equation ; Homonuclear molecule ; Analytical Chemistry (journal) ; Chemical physics ; Physical chemistry ; Thermodynamics ; Organic chemistry ; Composite material ; Chemistry ; Physics ; Activation energy Fullerene Chemistry and Applications ; Diamond and Carbon-based Materials Research ; Graphene research and applications
Authors: Nadia Kiran | Sadia Perveen | Seemab Bashir | Shamsul Qamar
Source: Thermal Science (article, 2020-12-04)
Field: Chemistry — Spectroscopy

A linearized non-isothermal general rate model for studying thermal effects in liquid chromatographic columns A linearized non-isothermal general rate model is formulated and analytically solved to quantify the effects of temperature variations in fixed-bed chromatographic columns. The model contains a set of four coupled PDE accounting for energy transfer resistances, inner and outer particle-pore diffusions, and interfacial mass and axial dispersion. The Laplace transform, the eigenvalue-decomposition technique, and a conventional technique for the solutions of ODE are jointly employed for the solution of the model equations. A few numerical test studies are considered to assess the impact of system parameters on the performance of packed-bed adsorption columns. To access the range of applicability and to get the scope of the appropriateness of calculated analytical results, the numerical results are also obtained by applying a high resolution finite volume scheme. The analytical solutions obtained can be used as an invaluable tool for analyzing, optimizing, and upgrading the non-isothermal liquid chromatographic procedures. Isothermal process ; Laplace transform ; Mechanics ; Thermodynamics ; Dispersion (optics) ; Eigenvalues and eigenvectors ; Materials science ; Ode ; Range (aeronautics) ; Mass transfer ; Volume (thermodynamics) ; Applied mathematics ; Mathematics ; Physics ; Mathematical analysis Analytical Chemistry and Chromatography ; Protein purification and stability ; Crystallization and Solubility Studies
Authors: Torsten Eckstein | Estefania Vidal-Henriquez | Azam Gholami
Source: Soft Matter (article, 2020-01-01)
Field: Materials Science — Materials Chemistry

Experimental observation of boundary-driven oscillations in a reaction–diffusion–advection system Boundary-driven oscillations were numerically predicted to exist in a reaction-diffusion-advection system, namely in the signaling population of social amoeba D. discoideum. If deprived of nutrients, D. discoideum aggregates by producing cAMP waves at precisely timed intervals. In the presence of an advecting flow, holding the upstream boundary to a zero concentration of cAMP produces an instability that sends periodic wave trains downstream. This instability is expected to exist at lower degradation rates of cAMP and thus provides a mechanism for wave creation in phosphodiesterase deficient systems, such as PdsA<sup>-</sup> cells. Degradation of extracellular cAMP by the enzyme phosphodiesterase PdsA is fundamental to successfully producing waves, regulating the external cAMP gradient field and preventing the accumulation of cAMP. Using a flow-through microfluidic setup filled with PdsA<sup>-</sup> cells, we confirm experimentally that boundary-driven oscillations indeed exist. Above a minimum flow velocity, decaying waves are induced, with a decay length that increases with the imposed flow velocity. We performed extensive numerical simulations and showed that these waves have a boundary-driven origin, where the lack of cAMP in the upstream flow destabilizes the system. We explored the properties of these waves and the parameter region where they exist, finding good agreement with our experimental observations. These results provide experimental confirmation of the destabilizing effect of the upstream boundary in an otherwise stable reaction-diffusion system. We expect this mechanism to be relevant for wave creation in other oscillatory or excitable systems that are incapable of wave generation in the absence of flow. Advection ; Diffusion ; Reaction–diffusion system ; Boundary (topology) ; Mechanics ; Physics ; Thermodynamics ; Mathematics ; Mathematical analysis Material Dynamics and Properties ; Nonlinear Dynamics and Pattern Formation ; Advanced Thermodynamics and Statistical Mechanics
Authors: John D. Schwarzkopf | Daniel Sheppard | J. E. Hammerberg | R. Schulze | J. C. Cooley | J. Goett | M. Grover | Brandon LaLone | R. Manzanares | J. I. Martinez | Martin Schauer | D. W. Schmidt | G. D. Stevens | W. D. Turley | W. T. Buttler
Source: AIP conference proceedings (article, 2020-01-01)
Field: Materials Science — Materials Chemistry

Modeling of cerium ejecta in helium and deuterium gases Shocked Ce metal in contact with a reactive gas such as H2 or D2 produces a distribution of ejecta particles that react with the gas to form Ce hydrides or deuterides. We present an average particle reaction diffusion model to calculate particle and gas temperatures and reaction fractions. We compare model results with recent HE driven Ce experiments into reactive D2 and non-reactive He gases for a variety of initial gas pressures from 2–8 atmospheres at initial temperatures of 300 K. We find consistent agreement with radiance temperature measurements as a function of time using particle distributions from Mie scattering data resulting in Ce deuteride mass conversion fractions in D2 gas of order 10 – 20 %. Deuterium ; Ejecta ; Helium ; Cerium ; Materials science ; Particle (ecology) ; Radiance ; Hydrogen ; Analytical Chemistry (journal) ; Atomic physics ; Chemistry ; Physics Nuclear Materials and Properties ; Nuclear reactor physics and engineering ; Quantum, superfluid, helium dynamics
Authors: José A. Carrillo | Francis Filbet | Markus Schmidtchen
Source: Numerische Mathematik (article, 2020-05-26)
Field: Materials Science — Materials Chemistry

Convergence of a finite volume scheme for a system of interacting species with cross-diffusion Abstract In this work we present the convergence of a positivity preserving semi-discrete finite volume scheme for a coupled system of two non-local partial differential equations with cross-diffusion. The key to proving the convergence result is to establish positivity in order to obtain a discrete energy estimate to obtain compactness. We numerically observe the convergence to reference solutions with a first order accuracy in space. Moreover we recover segregated stationary states in spite of the regularising effect of the self-diffusion. However, if the self-diffusion or the cross-diffusion is strong enough, mixing occurs while both densities remain continuous. Convergence (economics) ; Diffusion ; Scheme (mathematics) ; Finite volume method ; Volume (thermodynamics) ; Statistical physics ; Mathematics ; Applied mathematics ; Mathematical analysis ; Computer science ; Physics ; Mechanics ; Thermodynamics ; Economics Solidification and crystal growth phenomena ; Numerical methods for differential equations ; Gas Dynamics and Kinetic Theory
Authors: Max Boleininger | Martin Gallauer | Sergei L. Dudarev | Thomas D. Swinburne | Daniel R. Mason | Danny Perez
Source: Physical Review Research (article, 2020-11-18)
Field: Materials Science — Materials Chemistry

Statistical mechanics of kinks on a gliding screw dislocation This work presents a solution for the steady-state drift velocity of a screw dislocation subjected to shear stress. The authors find that the activation energy for drift is halved at high temperature, as the system crosses into the thermodynamic limit. Dislocation ; Work (physics) ; Statistical mechanics ; Shear (geology) ; Statistical analysis ; Energy (signal processing) Nonlocal and gradient elasticity in micro/nano structures ; Microstructure and mechanical properties ; Shape Memory Alloy Transformations
Authors: Shaban A. A. Abdel-Raheem | Adel M. Kamal El‐Dean | Reda Hassanien | Mohamed E. A. El-Sayed | Aly A. Abd-Ella
Source: Zenodo (CERN European Organization for Nuclear Research) (article, 2020-12-25)
Field: Chemistry — Organic Chemistry

Synthesis and biological activity of 2-((3-Cyano-4,6-distyrylpyridin-2-yl) thio) acetamide and its cyclized form In this paper, 2-((3-Cyano-4,6-distyrylpyridin-2-yl)thio)acetamide (2) and its cyclized form, 3-amino-4,6-distyrylthieno[2,3-b]pyridine-2-carboxamide (3), were prepared and their structure characterizations were performed by the means of elemental and spectroscopic analyses. Their biological activity as insecticides against cowpea aphid Aphis craccivora Koch using acetamiprid insecticide as a reference was studied. The bioassay results for compounds (2) and (3) against nymphs of cowpea aphid showed that the LC50 values were 0.192 and 0.841 ppm, respectively, after 24 h of treatment but the LC50 values were 0.041 and 0.095 ppm, respectively, after 48 h of treatment. Furthermore, the bioassay results for compounds (2) and (3) showed that the LC50 values were 1.233 and 2.949 ppm, respectively, after 24 h of treatment and the LC50 values were 0.142 and 0.270 ppm, respectively, after 48 h of treatment against adults of cowpea aphid. Given these observations, it has been found that there is a remarkable relationship between the biological activity and the structure of the used compounds. Acetamide ; Thio- ; Chemistry ; Biological activity ; Combinatorial chemistry ; Stereochemistry ; Organic chemistry ; Biochemistry ; In vitro Synthesis and Characterization of Heterocyclic Compounds ; Synthesis and biological activity
Authors: V. Ya. Horishny | Іryna Drapak | Taras Chaban | Yu. V. Ostapiuk | V. S. Matiychuk
Source: INDONESIAN JOURNAL OF PHARMACY (article, 2020-08-19)
Field: Chemistry — Organic Chemistry

Synthesis and antitumor properties of some new N-(5-R-benzyl-1,3-thiazol-2-yl)-4,5-dihydro-1H-imidazole-2-carboxamides New N-(5-R-benzyl-1,3-thiazol-2-yl)-2-morpholin-4-yl-2-oxoacetamides have been prepared in good yields via the reaction of N-(5-R-benzyl-1,3-thiazol-2-yl)-2-chloroacetamides with sulfur and morfoline. These compounds react with ethendiamine to form a series of novel N-[5-R-benzyl)-1,3-thiazol-2-yl]-4,5-dihydro-1H-imidazole-2-carboxamides with excellent yields. Anticancer activity screening of synthesized compounds was carried out within the framework of the Developmental Therapeutic Program of the National Cancer Institute's (DTP, NCI, Bethesda, Maryland, USA). It was shown that compounds are promising for new anticancer agents' search. Imidazole ; Chemistry ; Sulfur ; Stereochemistry ; Medicinal chemistry ; Combinatorial chemistry ; Organic chemistry Synthesis and biological activity ; Synthesis and Characterization of Heterocyclic Compounds ; Synthesis and Reactions of Organic Compounds