jablonkagroup/rise_ai_scientists huggingface dataset:
Authors: G. A. Ovchinnikov | Valentina А. Gorskikh | Ilyana I. Fassalovа | В. С. Тухватшин | Р. Ф. Талипов
Source: IZVESTIYA VYSSHIKH UCHEBNYKH ZAVEDENIY KHIMIYA KHIMICHESKAYA TEKHNOLOGIYA (article, 2018-12-12)
Field: Chemistry — Spectroscopy

KINETICS OF ADSORPTION OF 4,4-DIMETHYL-1,3-DIOXANE FROM AQUEOUS SOLUTIONS BY SYNTHETIC ZEOLITES IN PRESENCE OF PHOSPHORIC ACID In this paper we studied the kinetics of adsorption of 4,4-dimethyl-1,3-dioxane by synthetic zeolites from aqueous solutions in the presence of phosphoric acid. Kinetic mechanism of DMD adsorption from aqueous solutions by synthetic zeolites were considered from the position of three kinetic models: the diffusion model (Boyd and Morris-Weber model), Lagergeren (pseudo-first order), and pseudo-second order. As sorbents we have used synthetic zeolites KA, NaA, CaA, CaX, NaX with a pore diameter of 3-9 Å. DMD (boiling point is 113-114 ºC) was synthesized from isobutylene. Chromatographic analysis was performed on Chromatec Crystal 5000.1 instrument (Russia) using columns (2.0 m in length) with silicone SE-30 (5%) stationary phase (0.16–0.20 mm, operating temperature is 50–220 °C) with nitrogen as a carrier gas. An adsorption of DMD from aqueous solutions was investigated at (75±1) °C from a limited volume under constant mixing (laboratory mechanical stirrer, 17 rps). The contact time of the solution with samples of sorbents varied from 120 to 3600 s. The DMD concentration in solution was determined by the chromatographic method (the internal standard is 4,4,5-trimethyl-1,3-dioxane). The values of the external and internal mass transfer diffusion coefficients were obtained. The effect of the size of zeolite’s pores on the contribution of the external or internal diffusion mass transfer in the process of adsorption of 4,4-dimethyl-1,3-dioxane was founded. The time of establishment of sorption equilibrium was determined. We have found that the process of adsorption of DMD by synthetic zeolites in the presence of phosphoric acid is determined by the values of the diameter of the pores. It is shown that the value of pore diameter of synthetic zeolites does not influence on the аdsorption equilibrium time of DMD. The adsorption equilibrium time for all used family zeolites is 900 s. The kinetics of adsorption of DMD on synthetic zeolites can be correctly described by a pseudo-second-order equation, which indicates the presence of sorbate (DMD) interaction with the sorbent (synthetic zeolite). Aqueous solution ; Chemistry ; Adsorption ; Phosphoric acid ; Diffusion ; Mass transfer ; Sorption ; Boiling point ; Zeolite ; Chromatography ; Physical chemistry ; Organic chemistry ; Thermodynamics ; Catalysis Analytical Chemistry and Chromatography ; Inorganic and Organometallic Chemistry ; Adsorption, diffusion, and thermodynamic properties of materials
Authors: Yuming Zhang | Rongxuan Linghu | Lei Huang | Liang Zhang | Guogang Sun | Zhang Shu
Source: International Journal of Petrochemistry and Research (article, 2018-07-12)
Field: Chemistry — Analytical Chemistry

Effects of Secondary reaction of Primary Volatiles on Oil/gas Yield and Quality from Oil Shale Pyrolysis International Journal of Petrochemistry and Research (IJPR) is a peer-reviewed scientific journal offers original papers and reviews of theoretical and experimental studies concerned with current problems of petro chemistry and processing such as chemical composition of crude oils and natural gas liquids; petroleum refining (cracking, hydrocracking, and catalytic reforming); catalysts for petrochemical processes (hydrogenation, isomerization, oxidation, hydroformylation, etc.); activation and catalytic transformation of hydrocarbons and other components of petroleum, natural gas, and other complex organic mixtures; new petrochemicals including lubricants and additives; environmental problems; and information on scientific meetings relevant to these areas. Shale oil ; Diesel fuel ; Pyrolysis ; Chemistry ; Yield (engineering) ; Coke ; Boiling point ; Gasoline ; Oil shale ; Condensation ; Pulp and paper industry ; Distillation ; Vacuum distillation ; Chemical engineering ; Waste management ; Organic chemistry ; Petroleum ; Materials science ; Metallurgy Petroleum Processing and Analysis ; Hydrocarbon exploration and reservoir analysis ; Thermochemical Biomass Conversion Processes
Authors: Kheng Lim Goh | Maziyar Makaremi | Pooria Pasbakhsh | R. De Silva | Vladimir Živković
Source: Data in Brief (article, 2018-11-13)
Field: Materials Science — Polymers and Plastics

Dataset on structure and mechanical properties of electrospun polyacrylonitrile nanofibrous mesh reinforced by halloysite nanotubes The mechanical properties of electrospun polyacrylonitrile (PAN)-based membranes for ultrafiltration, such as oil-water separation and heavy metals from water, are often characterised in the dry state but little is known about the membrane properties in the hydrated state. This dataset comprised mechanical properties and structure-related properties of electrospun PAN-based membranes. The mechanical dataset described the yield strength and strain, stiffness, resilience energy, fracture strength, strain at fracture and fracture toughness of electrospun neat PAN and halloysite nanotube (HNT) reinforced PAN membranes in both hydrated and dry states. The data related to the hydrated state were derived from direct measurements of the mechanical properties of the PAN-based membrane using a novel environmental micromechanical tester. The structure-related dataset comprised electron micrographs and quantitative measurements (fibre diameter and pore diameter) derived from the micrographs. For further interpretation and discussion of the dataset, the reader is referred to the research data article, "Direct measurement of the elasticity and fracture properties of electrospun polyacrylonitrile/halloysite fibrous mesh in water" (Govindasamy et al., 2014). Polyacrylonitrile ; Halloysite ; Materials science ; Composite material ; Membrane ; Electrospinning ; Fracture toughness ; Nanofiber ; Polymer ; Chemistry Polymer Nanocomposites and Properties ; Electrospun Nanofibers in Biomedical Applications ; Clay minerals and soil interactions
Authors: Mohammed Ibrahim | Sayeed Abdullahi
Source: Bayero Journal of Pure and Applied Sciences (article, 2018-01-18)
Field: Materials Science — Materials Chemistry

Green synthesis of zinc nanoparticles using &lt;i&gt;Ipomoea asarifolia&lt;/i&gt; leaves extract and its adsorption properties for the removal of dyes In this paper, a green method is reported for the synthesis and characterization of zinc nanoparticles using Ipomoea asarifolia leaf extract as reducing and capping agent together with polyethylene glycol (PEG-10000) as stabilizing agent. The biosynthesized zinc nanoparticles were characterized by UV-Vis absorption spectroscopy, Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), and scanning electron microscopy (SEM); and were used as adsorbent for the removal of Bromophenol blue (BPB), and Eriochrome black T (EBT) dyes. Isotherms, kinetics and thermodynamics of the adsorption process were studied with the view to understand the adsorption mechanism. The adsorption isotherms were closely described by Freundlich isotherm model with correlation coefficient (R2) of 0.99. The adsorption kinetics data were well fitted by the pseudo-second-order rate model with high regression coefficient (0.998). The intra particle diffusion of BPB anId EBT on ZnNPs represents the rate-limiting step. The adsorption capacity increases with the increase in temperature (from 298 to 318K) and thermodynamic calculations suggested that the adsorption of the dyes onto ZnNPs is an endothermic process with ΔH values of 10.78kJ/mol for BPB and 14.14 kJ/mol for EBT respectively.Keywords: Adsorption, Bromophenol blue, Eriochrome black T, Ipomoea asarifolia, Zinc nanoparticles Adsorption ; Chemistry ; Nuclear chemistry ; Zinc ; Freundlich equation ; Nanoparticle ; Materials science ; Organic chemistry ; Nanotechnology Nanoparticles: synthesis and applications ; Medicinal Plants and Neuroprotection
Authors: Hirra Anjum | Mansoor Abdullah Obaid | Muhammad Yasir Shamim | T. Murugesan
Source: MATEC Web of Conferences (article, 2018-01-01)
Field: Materials Science — Materials Chemistry

Adsorption of Benzene by “Green” functionalization of Montmorillonite The capacity of organically modified Montmorillonite (MMT) clay to adsorb nonpolar organic compound (benzene) in an aqueous solution, was investigated under the batch process. MMT was pretreated (centrifuged) and then functionalized with green intercalating agent i.e. 1-hexyl-3-methyl imadazolium chloride [HMim][Cl]. The characterization through Fourir Transoform Infrared Spectroscopy (FTIR), Differential Scanning Calorimeter (DSC) and Field Emission Scanning Electron Microscope (FE-SEM) confirmed the presence of the oxygen containing functional groups, changes in melting point and variation in the morphological properties. The governing parameters for the sorption of benzene such as the effect of contact time, pH, adsorbent dose and rotation were studied. The kinetic data conformed to pseuodo 2 nd order kinetic model and the isotherm experimental data were a better fit to Langmuir model with maximum adsorption capacity of 588.23mg/g under experimental conditions. Overall, MMT intercalated with 1-hexyl-3-methyl imadazolium chloride is a promising environmental friendly adsorbent for the abatement of benzene in an aqueous solution. Adsorption ; Montmorillonite ; Chemistry ; Benzene ; Differential scanning calorimetry ; Aqueous solution ; Sorption ; Langmuir adsorption model ; Nuclear chemistry ; Fourier transform infrared spectroscopy ; Scanning electron microscope ; Inorganic chemistry ; Organic chemistry ; Chemical engineering ; Materials science Mesoporous Materials and Catalysis ; Adsorption and biosorption for pollutant removal ; Covalent Organic Framework Applications
Authors: Priscila Aires | Francisco Gambarra-Neto | W. M. Coutinho | A. E. de Araújo | Gilvan Ferreira da Silva | Josivanda Palmeira Gomes | Everaldo S. Medeiros
Source: Journal of Spectral Imaging (article, 2018-04-24)
Field: Chemistry — Analytical Chemistry

Near infrared hyperspectral images and pattern recognition techniques used to identify etiological agents of cottonanthracnose and ramulosis Hyperspectral imaging near infrared (HSI-NIR) has the potential to be used as a non-destructive approach for the analysis of new microbiological matrices of agriculture interest. This article describes a new method for accurately and rapidly classifying the etiological agents Colletotrichum gossypii (CG) and C. gossypii var. cephalosporioides (CGC) grown in a culture medium, using scattering reflectance HSI-NIR and multivariate pattern recognition analysis. Five strains of CG and 46 strains of CGC were used. CG and CGC strains were grown on Czapek-agar medium at 25 °C under a 12-hour photoperiod for 15 days. Molecular identification was performed as a reference for the CG and CGC classes by polymerase chain reaction of the intergenic spacer region of rDNA. The scattering coefficient µs and the absorption coefficient µa were obtained, which resulted in a µs value for CG of 1.37 × 1019 and for CGC of 5.83 × 10–11. These results showed that the use of the standard normal variate was no longer essential and reduced the spectral range from 1000–2500 nm to 1000–1381 nm. The results evidenced two type II errors for the CG 457-2 and CGC 39 samples in the soft independent modelling model of the analogy model. There were no classification errors using the algorithm of the successive projections for variable selection in linear discriminant analysis (SPA-LDA). A parallel validation of the results obtained with SPA-LDA was performed using a box plot analysis with the 11 variables selected by SPA, in which there were no outliers for the HSI-NIR models. The new HSI-NIR and SPA-LDA procedures for the classification of CG and CGC etiological agents are noted for their greater analytical speed, accuracy, simplicity, lower cost and non-destructive nature. Hyperspectral imaging ; Linear discriminant analysis ; Mathematics ; Pattern recognition (psychology) ; Analytical Chemistry (journal) ; Horticulture ; Artificial intelligence ; Physics ; Biology ; Chromatography ; Statistics ; Chemistry ; Computer science Spectroscopy and Chemometric Analyses ; Spectroscopy Techniques in Biomedical and Chemical Research ; Essential Oils and Antimicrobial Activity
Authors: Felipe Souza Oliveira | Ana Carolina Fávero | Sérgio Tuan Renosto | M. S. da Luz | C. A. M. dos Santos
Source: Materials Research (article, 2018-04-28)
Field: Materials Science — Materials Chemistry

Kinetics of Vacancy Doping in SrTiO3 Studied by in situ Electrical Resistivity The kinetics of annealing to transform stoichiometric SrTiO3 insulator into a vacancy-doped semiconductor-superconductor was revisited by in situ electrical resistivity measurements. SrTiO3 single crystals were grown by Floating Zone Method. Using a homemade apparatus several electrical resistivity as a function of time were measured at different temperatures, which allows one to study the creation of vacancies during annealing under vacuum. The activation energy for the oxygen vacancies formation/charge doping in SrTiO3 was estimated as 1.4±0.3 eV using solid-state kinetics approach. Electrical resistivity and conductivity ; Annealing (glass) ; Doping ; Kinetics ; Materials science ; Activation energy ; Vacancy defect ; Semiconductor ; Insulator (electricity) ; Stoichiometry ; Analytical Chemistry (journal) ; Condensed matter physics ; Chemistry ; Optoelectronics ; Physical chemistry ; Metallurgy ; Electrical engineering ; Physics Electronic and Structural Properties of Oxides ; Ferroelectric and Piezoelectric Materials ; Magnetic and transport properties of perovskites and related materials
Authors: Sonja Herrmann | Tabea Schübel | Fanny Nascimento Costa | Maria Letícia de Castro Barbosa | Fábio Furlan Ferreira | Thays Lima Matos Freire Dias | Morgana Vital de Araújo | Magna Suzana Alexandre‐Moreira | Lı́dia Moreira Lima | Stefan Laufer | Eliezer J. Barreiro
Source: Anais da Academia Brasileira de Ciências (article, 2018-01-01)
Field: Chemistry — Organic Chemistry

Synthesis, X-ray diffraction study and pharmacological evaluation of 3-amino-4-methylthiophene-2-acylcarbohydrazones N-acylhydrazone is an interesting privileged structure that has been used in the molecular design of a myriad of bioactive compounds. In order to identify new antinociceptive drug candidates, we described herein the design, synthesis, X-ray diffraction study and the pharmacological evaluation of a series of 3-amino-4-methylthiophene-2-acylcarbohydrazone derivatives (8a-t). Compounds were prepared in good overall yields through divergent synthesis from a common key intermediate and were characterized by classical spectroscopy methods. X-ray diffraction study was employed for unequivocal determination of the imine double bond stereochemistry. 8a-t were evaluated in vivo through oral administration using the classical writhing test in mice. N-acylhydrazone derivatives 8j and 8l displayed relative potency similar to dipyrone, highlighting them as promising analgesic lead-candidates for further investigation. Chemistry ; Imine ; Stereochemistry ; Potency ; In vivo ; Molecule ; X-ray crystallography ; Combinatorial chemistry ; Diffraction ; Crystallography ; In vitro ; Organic chemistry ; Biochemistry ; Biology ; Biotechnology Synthesis and biological activity ; Metal complexes synthesis and properties ; Synthesis and Reactivity of Heterocycles
Authors: Sreenivasulareddy Bandatmakuru | Veera Reddy Arava
Source: SynOpen (article, 2018-10-01)
Field: Chemistry — Organic Chemistry

Novel Synthesis of 1,2-Substituted 4-Quinolones An efficient method for the straightforward synthesis of N-functionalized 4-quinolones and 1,2-substituted 4-quinolones from simple 2-aminoacetophenones has been developed. Simple (philosophy) ; Combinatorial chemistry ; Chemistry ; Computer science ; Philosophy Synthesis and Biological Evaluation ; Multicomponent Synthesis of Heterocycles ; Synthesis and Reactivity of Heterocycles
Authors: Michael Brunsteiner | Johannes Khinast | Amrit Paudel
Source: Preprints.org (preprint, 2018-06-11)
Field: Chemistry — Spectroscopy

Relative Contributions of Solubility and Mobility to the Stability of Amorphous Solid Dispersions of Poorly Soluble Drugs: A Molecular Dynamics Simulation Study Amorphous solid dispersions are considered a promising formulation strategy for the oral delivery of poorly soluble drugs. The limiting factor for the applicability of this approach is the physical (in)stability of the amorphous phase in solid samples. Minimizing the risk of reduced shelf life for a new drug by establishing a suitable excipient/polymer-type from first principles would be desirable to accelerate formulation development. Here we perform Molecular Dynamics simulations to determine properties of blends of eight different polymer-small molecule drug combinations for which stability data is available from a consistent set of literature data. We calculate thermodynamic factors (mixing energies) as well as mobilities (diffusion rates and roto-vibrational fluctuations). We find that either of the two factors, mobility and energetics, can determine the relative stability of the amorphous form for a given drug. Which factor is rate limiting depends on physico-chemical properties of the drug and the excipients/polymers. The methods outlined here can be readily employed for an in-silico pre-screening of different excipients for a given drug to establish a qualitative ranking of the expected relative stabilities, thereby accelerating and streamlining formulation development. Amorphous solid ; Excipient ; Molecular dynamics ; Polymer ; Solubility ; Materials science ; Mixing (physics) ; Limiting ; Chemical stability ; Chemistry ; Thermodynamics ; Computational chemistry ; Organic chemistry ; Chromatography ; Physics Analytical Chemistry and Chromatography ; Drug Solubulity and Delivery Systems ; Thermodynamic properties of mixtures
Authors: Eric J. Chan | Marcus A. Neumann
Source: Journal of Chemical Theory and Computation (article, 2018-03-07)
Field: Materials Science — Materials Chemistry

Evaluation of General and Tailor Made Force Fields via X-ray Thermal Diffuse Scattering Using Molecular Dynamics and Monte Carlo Simulations of Crystalline Aspirin We have performed a comparison of the experimental thermal diffuse scattering (TDS) from crystalline Aspirin (form I) to that calculated from molecular dynamics (MD) simulations based on a variety of general force fields and a tailor-made force field (TMFF). A comparison is also made with Monte Carlo (MC) simulations which use a "harmonic network" approach to describe the intermolecular interactions. These comparisons were based on the hypothesis that TDS could be a useful experimental data in validation of such simulation parameter sets, especially when calculations of dynamical properties (e.g., thermodynamic free energies) from molecular crystals are concerned. Currently such a validation of force field parameters against experimental data is often limited to calculation of specific physical properties, e.g., absolute lattice energies usually at 0 K or heat capacity measurements. TDS harvested from in-house or synchrotron experiments comprises highly detailed structural information representative of the dynamical motions of the crystal lattice. Thus, TDS is a well-suited experimental data-driven means of cross validating theoretical approaches targeted at understanding dynamical properties of crystals. We found from the results of our investigation that the TMFF and COMPASS (from the commercial software "Materials Studio") parameter sets gave the best agreement with experiment. From our homologous MC simulation analysis we are able to show that force constants associated with the molecular torsion angles are likely to be a strong contributing factor for the apparent reason why these aforementioned force fields performed better. Force field (fiction) ; Monte Carlo method ; Molecular dynamics ; Statistical physics ; Intermolecular force ; Heat capacity ; Lattice energy ; Physics ; Scattering ; Materials science ; Thermodynamics ; Crystal structure ; Chemistry ; Molecule ; Crystallography ; Optics X-ray Diffraction in Crystallography ; Thermal and Kinetic Analysis ; Crystallography and molecular interactions
Authors: Andrea Grisafi | David M. Wilkins | Benjamin Meyer | Alberto Fabrizio | Clémence Corminbœuf | Michele Ceriotti
Source: arXiv (Cornell University) (preprint, 2018-09-14)
Field: Materials Science — Materials Chemistry

A Transferable Machine-Learning Model of the Electron Density The electronic charge density plays a central role in determining the behavior of matter at the atomic scale, but its computational evaluation requires demanding electronic-structure calculations. We introduce an atom-centered, symmetry-adapted framework to machine-learn the valence charge density based on a small number of reference calculations. The model is highly transferable, meaning it can be trained on electronic-structure data of small molecules and used to predict the charge density of larger compounds with low, linear-scaling cost. Applications are shown for various hydrocarbon molecules of increasing complexity and flexibility, and demonstrate the accuracy of the model when predicting the density on octane and octatetraene after training exclusively on butane and butadiene. This transferable, data-driven model can be used to interpret experiments, initialize electronic structure calculations, and compute electrostatic interactions in molecules and condensed-phase systems. Electronic structure ; Valence (chemistry) ; Linear scale ; Charge (physics) ; Charge density ; Density functional theory ; Scaling ; Statistical physics ; Physics ; Computer science ; Chemical physics ; Chemistry ; Molecular physics ; Quantum mechanics ; Mathematics Machine Learning in Materials Science ; Computational Drug Discovery Methods ; Various Chemistry Research Topics
Authors: Xikai Jiang | Jiyuan Li | Victor Lee | Heinrich M. Jaeger | Olle G. Heinonen | Juan J. de Pablo
Source: The Journal of Chemical Physics (article, 2018-06-18)
Field: Chemistry — Physical and Theoretical Chemistry

Evolutionary strategy for inverse charge measurements of dielectric particles We report a computational strategy to obtain the charges of individual dielectric particles from experimental observation of their interactions as a function of time. This strategy uses evolutionary optimization to minimize the difference between trajectories extracted from the experiment and simulated trajectories based on many-particle force fields. The force fields include both Coulombic interactions and dielectric polarization effects that arise due to particle-particle charge mismatch and particle-environment dielectric contrast. The strategy was applied to systems of free falling charged granular particles in a vacuum, where electrostatic interactions are the only driving forces that influence the particles' motion. We show that when the particles' initial positions and velocities are known, the optimizer requires only an initial and final particle configuration of a short trajectory in order to accurately infer the particles' charges; when the initial velocities are unknown and only the initial positions are given, the optimizer can learn from multiple frames along the trajectory to determine the particles' initial velocities and charges. While the results presented here offer a proof-of-concept demonstration of the proposed ideas, the proposed strategy could be extended to more complex systems of electrostatically charged granular matter. Dielectric ; Trajectory ; Charge (physics) ; Charged particle ; Electrostatics ; Inverse ; Polarization (electrochemistry) ; Particle (ecology) Electrostatics and Colloid Interactions ; Material Dynamics and Properties ; Modular Robots and Swarm Intelligence