jablonkagroup/rise_ai_scientists huggingface dataset:
Authors: Mei Yun | Ying-Yu Lin | Haiyang Jiang
Source:  (article, 2018-08-01)
Field: Chemistry — Spectroscopy

Diffusion Model of Drug Concentration and Application in Industrial Design the diffusion model of drug concentration is constructed using pharmacokinetics, initial conditions and boundary conditions. Item z is fixed at a certain value while the concentration is expressed as a function of radius and time, basically decreases along the radial direction and increases over time. Moreover, concentration diffusion in the radial direction is subjected to vascular wall constraints with on z on infinite boundary, while concentration diffusion in the axial direction propagates in ellipsoid. At last, this paper discusses its application in industrial design. Diffusion ; RADIUS ; Ellipsoid ; Boundary value problem ; Mechanics ; Diffusion equation ; Boundary (topology) ; Materials science ; Function (biology) ; Chemistry ; Physics ; Mathematical analysis ; Computer science ; Mathematics ; Engineering ; Thermodynamics Analytical Chemistry and Chromatography ; Chromatography in Natural Products ; Computational Drug Discovery Methods
Authors: Yiming Fan
Source: OakTrust (Texas A&M University Libraries) (article, 2018-07-30)
Field: Materials Science — General Materials Science

Modeling Moisture Diffusion Behaviors in Polymers and Polymer Composites This study presents a transient analysis of fluid diffusion behavior in polymers, fiber reinforced polymer (FRP) composites, and polymeric sandwich composites. The studied polymers and polymer composites consist of pure resins and polymeric foams, which are considered to have isotropic diffusion behavior; FRP composites, which typically have anisotropic diffusion behavior because of the presence of the fibers; and sandwich composites, which have different constitutes with different diffusion behaviors at various geometries. Diffusivity coefficients are first determined by assuming the diffusion to follow the classical Fickian diffusion. Different constitutive models are considered in order to understand the diffusion behavior of fluid through polymers and polymer composites. In some cases, fluid sorption led to quite significant changes of volume, and the diffusion process cannot be well described by the Fickian diffusion. In such situations, the coupled deformation-diffusion model for linear elastic isotropic materials is adopted, as a first approximation. This coupled deformation-diffusion model reduces to a Fickian diffusion model when the coupling parameters are absent and the volume changes in the solid polymers during diffusion are negligible. A finite difference method is used in order to solve for the coupled deformation-diffusion model. The coupled deformation-diffusion model is used to predict the one-dimensional moisture diffusion in thin polymer plates and the multi-axial three-dimensional moisture diffusion in dogbone specimens and polymeric foams. FRP composites typically have anisotropic diffusion behavior, where diffusivity in the fiber direction is faster than in the transverse direction. A micromechanical model that includes fiber volume contents and diffusivities of the constituents (fiber and matrix) is considered in order to gain fundamental insight into the effects of microstructural morphologies and constituents’ diffusivities on the diffusion process in the FRP specimens. The matrix and the fibers are modeled separately. And the micromechanical model is implemented in a continuum three-dimensional FE. The micromechanical model uses anisotropic diffusion constant from calibration and the simulation results are compared with the experimental results of thin laminates with different fiber arrangements. Finally, a multi-scale analysis of fluid diffusion in sandwich composites is performed. The simulation results are compared with the experimental data. Composite material ; Moisture ; Polymer ; Materials science ; Diffusion ; Thermodynamics Material Properties and Applications ; Rheology and Fluid Dynamics Studies ; Epoxy Resin Curing Processes
Authors: Ross J. Verploegh | Ying Wu | Salah Eddine Boulfelfel | David S. Sholl
Source: The Journal of Physical Chemistry (article, 2018-01-01)
Field: Chemistry — Inorganic Chemistry

Quantitative Predictions of Molecular Diffusion in Binary Mixed-Linker Zeolitic Imidazolate Frameworks Using Molecular Simulations C Experimental studies have shown that adsorbate diffusion in zeolitic imidazolate frameworks (ZIFs) can be tuned by incorporating two different imidazolate linkers in the ZIF crystals. We demonstrate for the first time that atomistic simulations are capable of quantitatively predicting self-diffusion in binary mixed-linker ZIFs. Diffusion coefficients of various adsorbates for which prior experimental data exist are predicted in ZIF-8-90, ZIF-8/SALEM-2 materials composed of imidazolate and 2-methylimidazolate linkers in the cubic SOD topology, and ZIF-7-90 materials over a composition range that is known experimentally to be in the SOD topology. A combination of conventional and biased molecular dynamics simulations as well as a previously developed lattice-diffusion model allows us to access the full range of diffusion time scales for adsorbates such as small hydrocarbons, alcohols, benzene, and water. Zeolitic imidazolate framework ; Chemistry ; Imidazolate ; Molecular dynamics ; Diffusion ; Linker ; Metal-organic framework ; Chemical physics ; Binary number ; Benzene ; Topology (electrical circuits) ; Thermodynamics ; Computational chemistry ; Physical chemistry ; Inorganic chemistry ; Organic chemistry ; Adsorption Metal-Organic Frameworks: Synthesis and Applications ; Lanthanide and Transition Metal Complexes ; Mesoporous Materials and Catalysis
Authors: Suxiao Wang | Alina Thorn | Gareth Redmond
Source: The Journal of Physical Chemistry (article, 2018-01-01)
Field: Chemistry — Physical and Theoretical Chemistry

Photophysical Probing of Dye Microenvironment, Diffusion Dynamics, and Energy Transfer C The objective of this work was to apply an organic dye, tetraphenylporphrin (TPP), to probe the aggregation state, microviscosity, and diffusion dynamics of dye molecules within the interior microenvironment of conjugated polymer poly[(9,9-dioctylfluorenyl-2,7-diyl)-co-(2,5-p-xylene)] nanoparticles (PFX NPs) which should open up further prospects in designing new porphyrin based nanoparticle materials and improve the knowledge of the better design of the nanophotonic devices based on dye-doped polymer NPs. This designed, aggregation-free TPP-doped PFX NPs system, exhibited remarkably high Forster resonance energy transfer (FRET) efficiency, leading to a potential application as a light harvesting system or a loadable drug carrier. To this end, different concentrations of TPP were doped into PFX NPs, prepared using a reprecipitation method. To compare TPP in organic solvent with TPP within the NP microenvironment, a successful doping of TPP into PFX NPs and no TPP aggregation formed inside of the NPs were indicated. Diffusion dynamics, location and degree of freedom of TPP in the PFX NPs were investigated using time-resolved anisotropy measurements fit with a “wobbling-in-cone and lateral diffusion” model. TPP molecules were found to wobble inside the core of NPs at a semiangle of ca. 70° and laterally diffuse on the NP surface with a diffusion coefficient of ca. 10–⁴ cm² s–¹. The microviscosity of the nanoparticles was calculated from the wobbling model as 0.9–1.2 cP which is higher than the viscosity of THF (0.48 cP). By increasing the concentration of TPP from 0 to 5 wt %, the emission color could be gradually tuned from violet to red. Stern–Volmer analysis indicates that a single TPP molecule can quench 12 PFX polymer chains, and at 5 wt % TPP, PFX emission was almost completely quenched. The emission intensity of TPP in PFX NPs is 70 times higher than in organic solvent with the excitation wavelength at 350 nm which highlights the excellent sensitization properties of this system. The combined energy diffusion and Forster energy transfer model was used to simulate the relationship of nanoparticle sizes and the energy transfer efficiency. Both of the simulation and experimental results indicate that in this system, the FRET efficiency increases with the dye density increasing and they increase gradually for small particles range of 5–20 nm, approaching constant value for particle radii above 30 nm. The exciton diffusion length was estimated as 6.5 nm. Microviscosity ; Chemistry ; Nanoparticle ; Förster resonance energy transfer ; Diffusion ; Molecule ; Polymer ; Chemical engineering ; Chemical physics ; Nanotechnology ; Fluorescence ; Organic chemistry ; Materials science Photochemistry and Electron Transfer Studies ; Porphyrin and Phthalocyanine Chemistry ; Photodynamic Therapy Research Studies
Authors: Xiaomei Wang | Xiang Mao | Jianhan Huang
Source: Colloids and Surfaces (article, 2018-01-01)
Field: Materials Science — Materials Chemistry

Hierarchical porous hyper-cross-linked polymers modified with phenolic hydroxyl groups and their efficient adsorption of aniline from aqueous solution A Physicochemical and engineering aspects Herein two hierarchical porous hyper-cross-linked polymers modified with phenolic hydroxyl (OH) groups were synthesized and their adsorption was comparatively evaluated using aniline as the adsorbate. The results reveal that the phenolic OH groups are helpful for the equilibrium adsorption due to the increased polar matching by formation of acid-base complex and hydrogen bonding, and the hierarchical porosity is favorable for the kinetic adsorption because the three dimensional continuous mesopores facilitate the rapid diffusion of aniline. The original aniline solution is optimum for the adsorption and the molecular state of aniline is preferable. The maximum equilibrium capacity is predicted to be 184.8 mg/g by the Langmuir model, and the enthalpy change, Gibbs free energy change, and entropy change are calculated to be negative. The adsorption can reach equilibrium within 60 min, the kinetic data obey the pseudo-second-order rate equation and the first step of the adsorption is mainly controlled by the intra-particle diffusion model. Adsorption ; Aniline ; Chemistry ; Gibbs free energy ; Aqueous solution ; Enthalpy ; Polymer ; Langmuir adsorption model ; Thermodynamics ; Chemical engineering ; Polymer chemistry ; Organic chemistry Covalent Organic Framework Applications ; Metal-Organic Frameworks: Synthesis and Applications ; Supramolecular Self-Assembly in Materials
Authors: U. Kaatze
Source:  (article, 2018-06-01)
Field: Materials Science — Materials Chemistry

Water: Why is it so Special? Molecular properties of the water molecule are reviewed with a view to their impact on the special features of that substance. In addition to the electrical charge distribution of the molecule, which effectuates the ability of forming hydrogen bonds and provides the molecule with a dipole moment, particular attention is paid to the smallness of the molecule. Among other influences it is essential for the high density of hydrogen bonding sites of water which is considered the key parameter in the defect diffusion model of the liquid dynamics. Dipole ; Chemical physics ; Molecule ; Hydrogen bond ; Moment (physics) ; Charge density ; Liquid water ; Diffusion ; Materials science ; Hydrogen ; Molecular dynamics ; Charge (physics) ; Computational chemistry ; Nanotechnology ; Chemistry ; Physics ; Thermodynamics ; Classical mechanics ; Organic chemistry Material Dynamics and Properties ; Thermodynamic properties of mixtures ; Spectroscopy and Quantum Chemical Studies
Authors: G. Callender | P. L. Lewin | G Montanari
Source: 2018 IEEE 2nd International Conference on Dielectrics (ICD) (article, 2018-07-01)
Field: Materials Science — Materials Chemistry

Simulation of Partial Discharge under Impulse Voltage Waveforms A drift diffusion model is used to investigate a PD between spherical electrodes coated by a dielectric material. The model geometry is an axisymmetric analog of crossed wire experiments which have been used in the literature to investigate PD activity due to impulse voltage waveforms. The simulation shows that discharges in crossed wire arrangements are likely to form surface ionising waves over the dielectric material covering the wires. This may allows the initiation of discharges at other locations where the electric field is high along the wires. The peak apparent current of this PD was found to be highly dependent on the applied voltage and exhibited a different pulse shape to PD inside spherical voids. The results suggest a significant factor behind the high magnitude discharges observed in impulse voltage waveform experiments may be the higher triggering voltage of the PD due to the impulse waveform. Impulse (physics) ; Waveform ; Voltage ; Partial discharge ; Materials science ; Electrode ; Dielectric ; Rotational symmetry ; Electric field ; High voltage ; Rise time ; Mechanics ; Acoustics ; Optics ; Physics ; Electrical engineering ; Optoelectronics ; Engineering ; Classical mechanics High voltage insulation and dielectric phenomena ; Electrostatic Discharge in Electronics ; Lightning and Electromagnetic Phenomena
Authors: А. В. Терлецкая | О. Б. Пупкова | В. В. Попова | Е. Ю. Алексеенко
Source: WATER AND WATER PURIFICATION TECHNOLOGIES SCIENTIFIC AND TECHNICAL NEWS (article, 2018-10-01)
Field: Chemistry — Analytical Chemistry

DETERMINATION OF VOLATILE HALOGEN-CONTAINING COMPOUNDS IN WATER POTABLE Biologically active substances of pharmaceutical chemicals are considered as ew environmental contaminants. They exhibit biological activity even at microconcentrations, especially during the interaction with each other. Therefore, it leads to a practical need of actually complete removal of pharmaceutical substances (PS) from aqueous solutions. The adsorption capacity of activated carbons (AC) and the necessary contact time are two key indicators, which are determined by the adsorption equilibrium and the kinetics of adsorption. Static adsorption can only predict the final equilibrium state of the system. Kinetic analysis allows us to determine the adsorbate uptake rate and the time required for the completion of the adsorption process. Thus, the use of kinetic models for describing sorption processes of PS extraction from diluted aqueous solutions can allow us to characterize the mechanism of PS sorption on AC with different porous structure and establish the limiting adsorption stage for subsequent determination of rational conditions of implementing the water treatment process.Adsorption methods are important for the micropollutant extraction from aqueous systems and may be used for this purpose Applicability of mathematical models for kinetic adsorption regularities estimation of sulfanilamide, sulfathiazole, levamisole, procaine and caffeine on active carbons with different porous structure was analyzed. Adequacy of diffusion models of Boyd and Morris-Weber in the initial area (up to F ÷ 0,4-0,6) kinetic curves was shown. The effective diffusion coefficients and adsorption rate constants of reviewed kinetic models increased in the series levamisole &lt; sulfathiazole &lt; procaine &lt; sulfanilamide &lt; caffeine. Pseudo-second order model reflects the adsorption regularities most accurately. Chemistry ; Adsorption ; Sorption ; Aqueous solution ; Diffusion ; Chromatography ; Thermodynamics ; Organic chemistry Analytical chemistry methods development ; Pharmaceutical and Antibiotic Environmental Impacts ; Analytical Chemistry and Chromatography
Authors: Syed R. Huq
Source: Rutgers University Community Repository (Rutgers University) (article, 2018-01-01)
Field: Materials Science — Materials Chemistry

Ion dynamics of ethylammonium nitrate by means of Quasielastic neutron scattering Ionic Liquids (ILs) are salts with a melting point below 100 ˚C. In recent years, ILs have garnered popular interest in academia and industry due to their unique properties and heterogeneous solvent nanostructure. In this Thesis, the solvent dynamics of one of the oldest, and most widely used ILs, ethylammonium nitrate (EAN) is examined using Quasi-Elastic Neutron Scattering (QENS) with H/D isotopic substitution. The data is fitted using analytical diffusions models and Bayesian statistics. The results show that long range cation motion in ILs is consistent with unrestricted (Fickian) translational diffusion. The measured cation diffusion coefficient of 3.96 × 10-11 m2/s (298 K) is comparable to other self-assembled systems and two orders of magnitude slower than for molecular liquids (e.g. water @ 292 K, D = 2.36 × 10-9 m2/s). The activation energy for all diffusion processes was independent of IL solvent within QENS instrument resolution and shown to follow Arrhenius dependence with temperature. These results demonstrate that long-range ion mobility in ILs is likely linked to revelations of long-range solvent nanostructure. Quasielastic neutron scattering ; Quasielastic scattering ; Ion ; Neutron scattering ; Nuclear physics ; Neutron ; Materials science ; Chemistry ; Small-angle neutron scattering ; Physics Chemical and Physical Properties of Materials ; Advanced Materials and Semiconductor Technologies ; Advanced Physical and Chemical Molecular Interactions
Authors: Swaminathan Subramanian | N. M. Imayathamizhan | A. Muthumanickkam | G. Baskar
Source: Desalination and Water Treatment (article, 2018-05-01)
Field: Materials Science — Biomaterials

Removal of methylene blue using polyacrylonitrile yarn waste/carboxylic group functionalized multiwall carbon nanotube nanofibrous composite Polyacrylonitrile ; Carbon nanotube ; Composite number ; Methylene blue ; Materials science ; Composite material ; Chemical engineering ; Nanotechnology ; Chemistry ; Organic chemistry ; Polymer ; Photocatalysis ; Engineering ; Catalysis Electrospun Nanofibers in Biomedical Applications ; Graphene and Nanomaterials Applications ; Adsorption and biosorption for pollutant removal
Authors: Vishal Metri | Swagata Ghatak | Soumyendu Raha | S.K. Sikdar
Source: Chemical Physics (article, 2018-07-27)
Field: Chemistry — Electrochemistry

Patch clamp data driven stochastic modeling and simulation of hTREK1 potassium ion channel gating Chemistry ; Gating ; Statistical physics ; Noise (video) ; Brownian motion ; Markov chain ; Biological system ; Physics ; Biophysics ; Computer science ; Quantum mechanics Electrochemical Analysis and Applications ; Nanopore and Nanochannel Transport Studies ; stochastic dynamics and bifurcation
Authors: Sanggeun Song | Seong Jun Park | Bong June Sung | Jun Soo Kim | Jihyun Kim | Jaeyoung Sung
Source: arXiv (Cornell University) (preprint, 2018-03-08)
Field: Materials Science — Materials Chemistry

Universal Transport Dynamics of Complex Fluids: Effects of Intrinsic and Extrinsic Disorder We present a general theory of thermal motion in disordered fluids, introducing a new type of random walk model with a sojourn time distribution dependent on hidden variables. This model encompasses Montroll and Weiss's continuous-time random walk (CTRW) model and the more recent, Chubinsky and Slater's stochastic diffusivity (SD) model. In the hydrodynamic limit, our model yields a new transport equation, which provides a unified, quantitative explanation of the anomalous transport dynamics commonly observed in various disordered fluids, including supercooled water, dense hard-disc fluids, and polymer fluids. We find that the long-time limit value of the product between the mean-square displacement (MSD) and the non-Gaussian parameter (NGP) serves as a useful measure of disorder. This measure is decomposable into extrinsic disorder, originating from environment-induced fluctuation in transport dynamics, and intrinsic disorder, originating from non-Fickian mean transport dynamics. Intrinsic disorder causes the MSD of disordered fluids to deviate from the prediction of the simple diffusion model or the SD model. Meanwhile, extrinsic disorder causes the NGP of disordered fluids to deviate from the CTRW model's prediction. By analyzing the MSD and NGP of supercooled water and dense hard-disc fluids, we find that extrinsic disorder is far more sensitive to temperature and density than intrinsic disorder. We also find that the NGP alone can serve as an ergodicity metric of transport systems; it vanishes for ergodic systems at long times, universally following inverse-time relaxation, but remains finite for non-ergodic systems. This work sets a new foundation for quantitative understanding of transport and transport-coupled processes in complex disordered media. Statistical physics ; Continuous-time random walk ; Random walk ; Ergodicity ; Mean squared displacement ; Supercooling ; Ergodic theory ; Physics ; Relaxation (psychology) ; Measure (data warehouse) ; Thermodynamics ; Mathematics ; Molecular dynamics ; Quantum mechanics ; Statistics ; Mathematical analysis Material Dynamics and Properties ; Phase Equilibria and Thermodynamics ; Theoretical and Computational Physics
Authors: Е. А. Корж | Н. А. Клименко
Source:  (article, 2018-01-01)
Field: Chemistry — Analytical Chemistry

KINETIC ADSORPTION MODELING OF PHARMACEUTICALS ON ACTIVATED CARBONS Biologically active substances of pharmaceutical chemicals are considered as ew environmental contaminants. They exhibit biological activity even at microconcentrations, especially during the interaction with each other. Therefore, it leads to a practical need of actually complete removal of pharmaceutical substances (PS) from aqueous solutions. The adsorption capacity of activated carbons (AC) and the necessary contact time are two key indicators, which are determined by the adsorption equilibrium and the kinetics of adsorption. Static adsorption can only predict the final equilibrium state of the system. Kinetic analysis allows us to determine the adsorbate uptake rate and the time required for the completion of the adsorption process. Thus, the use of kinetic models for describing sorption processes of PS extraction from diluted aqueous solutions can allow us to characterize the mechanism of PS sorption on AC with different porous structure and establish the limiting adsorption stage for subsequent determination of rational conditions of implementing the water treatment process. Adsorption methods are important for the micropollutant extraction from aqueous systems and may be used for this purpose Applicability of mathematical models for kinetic adsorption regularities estimation of sulfanilamide, sulfathiazole, levamisole, procaine and caffeine on active carbons with different porous structure was analyzed. Adequacy of diffusion models of Boyd and Morris-Weber in the initial area (up to F ÷ 0,4-0,6) kinetic curves was shown. The effective diffusion coefficients and adsorption rate constants of reviewed kinetic models increased in the series levamisole < sulfathiazole < procaine < sulfanilamide < caffeine. Pseudo-second order model reflects the adsorption regularities most accurately. Adsorption ; Chemistry ; Sorption ; Aqueous solution ; Diffusion ; Thermodynamics ; Chromatography ; Organic chemistry Analytical chemistry methods development ; Analytical Chemistry and Chromatography