jablonkagroup/rise_ai_scientists huggingface dataset:
Authors: Katherine Milton | Thomas R. Durrant | Teofilo Cobos Freire | Alexander L. Shluger
Source: Materials (article, 2023-02-07)
Field: Materials Science — Ceramics and Composites

Difference in Structure and Electronic Properties of Oxygen Vacancies in α-Quartz and α-Cristobalite Phases of SiO2 α-cristobalite (α-C) is a polymorph of silica, mainly found in space exploration and geochemistry research. Due to similar densities, α-C is often used as a proxy for amorphous SiO2, particularly in computer simulations of SiO2 surfaces and interfaces. However, little is known about the properties of α-C and its basic oxygen defects. Using density functional theory (DFT) simulations we provide a comprehensive report on the properties of perfect structure and oxygen vacancies in α-C. The calculated properties of α-C are compared with those of the better-characterized α-quartz (α-Q). Our results demonstrated that the positively charged O vacancy in α-C is most stable in the dimer configuration, in contrast to α-Q, which favors the puckered configuration. A back-projected configuration was also predicted in both polymorphs. We calculated the optical transition energies and isotropic hyperfine constants for O vacancies in both α-Q and α-C, and compared our findings with the results of previous studies and experiments. This work, thus, offers one of the first in-depth investigations of the properties of oxygen vacancies in α-C. Cristobalite ; Materials science ; Density functional theory ; Oxygen ; Amorphous solid ; Hyperfine structure ; Dimer ; Isotropy ; Chemical physics ; Electronic structure ; Quartz ; X-ray absorption fine structure ; Crystallography ; Computational chemistry ; Chemistry ; Atomic physics ; Nuclear magnetic resonance ; Physics ; Optics ; Spectroscopy Glass properties and applications ; High-pressure geophysics and materials ; Advanced ceramic materials synthesis
Authors: Anan Yaghmur | S. Moein Moghimi
Source: ACS Nano (review, 2023-11-09)
Field: Materials Science — Electronic, Optical and Magnetic Materials

Intrinsic and Dynamic Heterogeneity of Nonlamellar Lyotropic Liquid Crystalline Nanodispersions Nonlamellar lyotropic liquid crystalline (LLC) nanoparticles are a family of versatile nano-self-assemblies, which are finding increasing applications in drug solubilization and targeted drug delivery. LLC nanodispersions are heterogeneous with discrete nanoparticle subpopulations of distinct internal architecture and morphology, frequently coexisting with micelles and/or vesicles. Diversity in the internal architectural repertoire of LLC nanodispersions grants versatility in drug solubilization, encapsulation, and release rate. However, drug incorporation contributes to the heterogeneity of LLC nanodispersions, and on exposure to biological media, LLC nanodispersions often undergo nanostructural and morphological transformations. From a pharmaceutical perspective, coexistence of multiple types of nanoparticles with diverse structural attributes, together with media-driven transformations in colloidal characteristics, brings challenges in dissecting biological and therapeutic performance of LLC nanodispersions in a spatiotemporal manner. Here, we outline innate and acquired heterogeneity of LLC nanodispersions and discuss technological developments and alternative approaches needed to improve homogeneity of LLC formulations for drug delivery applications. Drug delivery ; Nanotechnology ; Nanoparticle ; Materials science ; Colloid ; Micelle ; Chemistry ; Aqueous solution Liquid Crystal Research Advancements ; Surfactants and Colloidal Systems ; Pickering emulsions and particle stabilization
Authors: Nicolas Steenbergen | Ivan Busha | Alexis Morgan | Collin Mattathil | Arieh Levy Pinto | Fotios Spyridakos | I. I. Sokolovskiy | Islam Bogachan Tahirbegi | Christopher A. R. Chapman | Estelle A. Cuttaz | Karina Litvinova | Josef Goding | Rylie A. Green
Source: APL Bioengineering (article, 2023-09-01)
Field: Materials Science — Polymers and Plastics

Surface electromyography using dry polymeric electrodes Conventional wet Ag/AgCl electrodes are widely used in electrocardiography, electromyography (EMG), and electroencephalography (EEG) and are considered the gold standard for biopotential measurements. However, these electrodes require substantial skin preparation, are single use, and cannot be used for continuous monitoring (>24 h). For these reasons, dry electrodes are preferable during surface electromyography (sEMG) due to their convenience, durability, and longevity. Dry conductive elastomers (CEs) combine conductivity, flexibility, and stretchability. In this study, CEs combining poly(3,4-ehtylenedioxythiophene):polystyrenesulfonate (PEDOT:PSS) in polyurethane are explored as dry, skin contacting EMG electrodes. This study compares these CE electrodes to commercial wet Ag/AgCl electrodes in five subjects, classifying four movements: open hand, fist, wrist extension, and wrist flexion. Classification accuracy is tested using a backpropagation artificial neural network. The control Ag/AgCl electrodes have a 98.7% classification accuracy, while the dry conductive elastomer electrodes have a classification accuracy of 99.5%. As a conclusion, PEDOT based dry CEs were shown to successfully function as on-skin electrodes for EMG recording, matching the performance of Ag/AgCl electrodes, while addressing the need for minimal skin prep, no gel, and wearable technology. PEDOT:PSS ; Electrode ; Electromyography ; Materials science ; Biomedical engineering ; Elastomer ; Electrical conductor ; Electroencephalography ; Composite material ; Medicine ; Physical medicine and rehabilitation ; Layer (electronics) ; Chemistry Conducting polymers and applications ; Advanced Sensor and Energy Harvesting Materials ; Muscle activation and electromyography studies
Authors: Poornima Singh | Vinay Kumar Pandey | Sourav Chakraborty | Kshirod Kumar Dash | Rahul Singh | Ayaz Mukarram Shaikh | Béla Kovács
Source: Heliyon (article, 2023-11-19)
Field: Chemistry — Inorganic Chemistry

Ultrasound-assisted extraction of phytochemicals from green coconut shell: Optimization by integrated artificial neural network and particle swarm technique This study employs artificial neural network (ANN) and particle swarm optimization (PSO) to maximize antioxidant and antimicrobial activity from green coconut shells. Phytochemical analysis was carried out on the extract obtained from ultrasound-assisted extraction performed at different combinations of time (10, 20, and 30 min), temperature (30, 35, and 40 <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mrow><mml:mo>°C</mml:mo></mml:mrow></mml:math>), and the ratio of solid-solvent (1:10, 1:20, and 1:30 g/ml). The presence of these bioactive compounds exhibits antimicrobial and antioxidant activities. Quantitative analysis showed that the total phenolic compounds ranged from 7.08 to 33.46 mg GAE/g, flavonoids ranged from 2.09 to 28.46 mg QE/g, tannins ranged from 70.5 to 141.09 mg TAE/g, and antioxidant activity of 49.98-66.1 %. The FTIR analysis detected the presence of C[bond, double bond]O, O-H, and C-H bonds. The optimized condition of ultrasound-assisted extraction (UAE) was compared with the optimized condition of the microwave. The result of ultrasound-assisted extraction was observed to be better than microwave-assisted extraction. Particle swarm optimization ; Artificial neural network ; Extraction (chemistry) ; Ultrasound ; Shell (structure) ; Biological system ; Artificial intelligence ; Engineering ; Computer science ; Materials science ; Biology ; Chromatography ; Machine learning ; Chemistry ; Physics ; Acoustics ; Mechanical engineering Coconut Research and Applications ; Spectroscopy and Chemometric Analyses ; Edible Oils Quality and Analysis
Authors: С. А. Зелепугин | Roman O. Cherepanov | Nadezhda V. Pakhnutova
Source: Materials (article, 2023-08-03)
Field: Materials Science — Materials Chemistry

Optimization of Johnson–Cook Constitutive Model Parameters Using the Nesterov Gradient-Descent Method Numerical simulation of impact and shock-wave interactions of deformable solids is an urgent problem. The key to the adequacy and accuracy of simulation is the material model that links the yield strength with accumulated plastic strain, strain rate, and temperature. A material model often used in engineering applications is the empirical Johnson-Cook (JC) model. However, an increase in the impact velocity complicates the choice of the model constants to reach agreement between numerical and experimental data. This paper presents a method for the selection of the JC model constants using an optimization algorithm based on the Nesterov gradient-descent method. A solution quality function is proposed to estimate the deviation of calculations from experimental data and to determine the optimum JC model parameters. Numerical calculations of the Taylor rod-on-anvil impact test were performed for cylindrical copper specimens. The numerical simulation performed with the optimized JC model parameters was in good agreement with the experimental data received by the authors of this paper and with the literature data. The accuracy of simulation depends on the experimental data used. For all considered experiments, the calculation accuracy (solution quality) increased by 10%. This method, developed for selecting optimized material model constants, may be useful for other models, regardless of the numerical code used for high-velocity impact simulations. Gradient descent ; Descent (aeronautics) ; Constitutive equation ; Applied mathematics ; Mathematics ; Computer science ; Algorithm ; Artificial intelligence ; Engineering ; Artificial neural network ; Structural engineering ; Finite element method High-Velocity Impact and Material Behavior ; Advanced Surface Polishing Techniques ; Advanced machining processes and optimization
Authors: Qiulin You | David B. Collum
Source: Journal of the American Chemical Society (article, 2023-10-19)
Field: Chemistry — Organic Chemistry

Carbon–Nitrogen Bond Formation Using Sodium Hexamethyldisilazide: Solvent-Dependent Reactivities and Mechanisms The solvent-dependent reactivity of sodium hexamethyldisilazide (NaHMDS) toward carbon-centered electrophiles reveals reactions that are poorly represented or unrepresented in the literature, including direct aminolysis of aromatic methyl esters to give carboxamides, nitriles, or amidines, depending on the choice of solvent. S<sub>N</sub>Ar substitutions of aryl halides and opening of terminal epoxides are also examined. A combination of <sup>1</sup>H and <sup>29</sup>Si nuclear magnetic resonance (NMR) spectroscopic studies using [<sup>15</sup>N]NaHMDS, kinetic studies, and computational studies reveals the complex mechanistic basis of the preferences for simple aryl carboxamides in toluene and dimethylethylamine and arylnitriles or amidines in tetrahydrofuran (THF). A prevalence of dimer- and mixed dimer-based chemistry even starting from the observable NaHMDS monomer in THF solution is notable. Chemistry ; Tetrahydrofuran ; Aryl ; Electrophile ; Solvent ; Toluene ; Dimer ; Aminolysis ; Reactivity (psychology) ; Carbanion ; Organic chemistry ; Medicinal chemistry ; Alkyl ; Catalysis Coordination Chemistry and Organometallics ; Asymmetric Hydrogenation and Catalysis ; Catalytic Cross-Coupling Reactions
Authors: M.A.M. Uosif | Shams A.M. Issa | Antoaneta Ene | A.M.A. Mostafa | Ali Atta | E.F. El Agammy | Hesham M.H. Zakaly
Source: Materials (article, 2023-04-12)
Field: Materials Science — Materials Chemistry

Lead-Free Ternary Glass for Radiation Protection: Composition and Performance Evaluation for Solar Cell Coverage Solar cells in superstrate arrangement need a protective cover glass as one of its main components. The effectiveness of these cells is determined by the cover glass's low weight, radiation resistance, optical clarity, and structural integrity. Damage to the cell covers brought on by exposure to UV irradiation and energetic radiation is thought to be the root cause of the ongoing issue of a reduction in the amount of electricity that can be generated by solar panels installed on spacecraft. Lead-free glasses made of xBi<sub>2</sub>O<sub>3</sub>-(40 - x)CaO-60P<sub>2</sub>O<sub>5</sub> (x = 5, 10, 15, 20, 25, and 30 mol%) were created using the usual approach of melting at a high temperature. The amorphous nature of the glass samples was confirmed using X-ray diffraction. At energies of 81, 238, 356, 662, 911, 1173, 1332, and 2614 keV, the impact of various chemical compositions on gamma shielding in a phospho-bismuth glass structure was measured. The evaluation of gamma shielding revealed that the results of the mass attenuation coefficient of glasses increase as the Bi<sub>2</sub>O<sub>3</sub> content increases but decrease as the photon energy increases. As a result of the study conducted on the radiation-deflecting properties of ternary glass, a lead-free low-melting phosphate glass that exhibited outstanding overall performance was developed, and the optimal composition of a glass sample was identified. The 60P<sub>2</sub>O<sub>5</sub>-30Bi<sub>2</sub>O<sub>3</sub>-10CaO glass combination is a viable option for use in radiation shielding that does not include lead. Materials science ; Amorphous solid ; Electromagnetic shielding ; Lead glass ; Radiation ; Irradiation ; Radiation damage ; Composite material ; Optics ; Chemistry ; Nuclear physics Radiation Shielding Materials Analysis ; Glass properties and applications ; Nuclear materials and radiation effects
Authors: Ehab A. Abdelrahman | Faisal K. Algethami | Huda Salem AlSalem | Mona Saad Binkadem | M. Khaіry | Fawaz A. Saad | Gharieb S. El‐Sayyad | Zahrah Alqahtani
Source: Inorganics (article, 2023-08-12)
Field: Chemistry — Organic Chemistry

Efficient Disposal of Rhodamine 6G and Acid Orange 10 Dyes from Aqueous Media Using ZrO2/CdMn2O4/CdO as Novel and Facilely Synthesized Nanocomposites It is essential to remove rhodamine 6G and acid orange 10 dyes from contaminated water because they can induce cancer and irritate the lungs, skin, mucous, membranes, and eyes. Hence, in the current work, the Pechini sol–gel method was used for the facile synthesis of ZrO2/CdMn2O4/CdO as novel nanocomposites at 600 and 800 °C. The synthesized nanocomposites were used as novel adsorbents for the efficient removal of rhodamine 6G and acid orange 10 dyes from aqueous media. The nanocomposites, which were synthesized at 600 and 800 °C, were abbreviated as EK600 and EK800, respectively. The synthesized nanocomposites were characterized by EDS, XRD, N2 adsorption/desorption analyzer, and FE-SEM. The patterns of XRD showed that the average crystal size of the EK600 and EK800 nanocomposites is 68.25 and 85.32 nm, respectively. Additionally, the images of FE-SEM showed that the surface of the EK600 nanocomposite consists of spherical, polyhedral, and rod shapes with an average grain size of 99.36 nm. Additionally, the surface of the EK800 nanocomposite consists of polyhedral and spherical shapes with an average grain size of 143.23 nm. In addition, the BET surface area of the EK600 and EK800 nanocomposites is 46.33 and 38.49 m2/g, respectively. The optimal conditions to achieve the highest removal of rhodamine 6G and acid orange 10 dyes are pH = 8, contact time = 24 min, and temperature = 298 kelvin. The greatest removal capacity of the EK600 and EK800 adsorbents towards rhodamine 6G dye is 311.53 and 250.63 mg/g, respectively. Additionally, the greatest removal capacity of the EK600 and EK800 adsorbents towards acid orange 10 dye is 335.57 and 270.27 mg/g, respectively. The removal of rhodamine 6G and acid orange 10 dyes using the EK600 and EK800 adsorbents is spontaneous, exothermic, follows the Langmuir adsorption isotherm, and fits well with the pseudo-first-order kinetic model. Rhodamine 6G ; Nanocomposite ; Materials science ; Adsorption ; Aqueous solution ; Rhodamine B ; Nuclear chemistry ; Desorption ; Specific surface area ; Rhodamine ; Chemical engineering ; Nanotechnology ; Chemistry ; Fluorescence ; Organic chemistry ; Photocatalysis ; Molecule Nanomaterials for catalytic reactions ; Adsorption and biosorption for pollutant removal ; Dye analysis and toxicity
Authors: Utku Gürel | Andrea Giuntoli
Source: Macromolecules (article, 2023-07-20)
Field: Materials Science — Surfaces, Coatings and Films

Shear Thinning from Bond Orientation in Model Unentangled Bottlebrush Polymer Melts The rheology of molecular brushes remains challenging to control due to the multiple length scales and relaxation processes involved and the lack of direct observation of molecular conformation during flow. We use molecular dynamics simulations to determine the shear thinning of unentangled bottlebrush polymers with varying architecture, from linear chains to combs, to densely grafted bottlebrushes, to star-like and star polymers. We find shear thinning exponents in line with theoretical and experimental results and characterize the shape and orientation of bottlebrushes in steady-state flow. Many shape parameters derived from the gyration tensor show molecular alignment with the flow for all systems. Yet, the orientation of individual bonds is what most strongly correlates with the architecture-dependent shear-thinning exponents. In densely grafted bottlebrushes, the packing of side chains prevents alignment with the flow, causing a reduction in shear thinning. The molecular insight from our simulations is useful to tune the architecture of bottlebrushes to control their rheology. Shear thinning ; Thinning ; Shear flow ; Rheology ; Radius of gyration ; Materials science ; Chemical physics ; Gyration ; Polymer ; Molecular dynamics ; Side chain ; Shear (geology) ; Polymer chemistry ; Mechanics ; Chemistry ; Composite material ; Physics ; Geometry ; Computational chemistry ; Mathematics Polymer Surface Interaction Studies ; Force Microscopy Techniques and Applications ; Rheology and Fluid Dynamics Studies
Authors: Hossein Pourrahmani | Mohammad Mohammadi | Bahar Pourhasani | Ayat Gharehghani | Mahdi Moghimi | Jan Van herle
Source: Scientific Reports (article, 2023-10-21)
Field: Chemistry — Inorganic Chemistry

Simulation and optimization of the impacts of metal-organic frameworks on the hydrogen adsorption using computational fluid dynamics and artificial neural networks One of the barriers to further commercialization of the proton exchange membrane fuel cell (PEMFC) is hydrogen storage. Conventional methods are based on pressurizing the hydrogen up to 700 bar. The focus of this study is to characterize the hydrogen storage capacity of hydrogen tanks filled with MOF-5 at low pressures. Thus, Computational Fluid Dynamic (CFD) was used in a transient condition to analyze the hydrogen storage. Benefiting from the CFD model, three input parameters of the MOF-5, namely, density, specific heat, and conductivity, were utilized to develop an artificial neural network (ANN) model to find the highest mass of adsorption at the lowest required pressure. The optimum possible MOF among 729220 different possibilities, which enables the adsorption of 0.0099 kg at 139 bar, was found using a newly defined parameter called Pressure Adsorption Parameter (PAP). Hydrogen ; Computational fluid dynamics ; Adsorption ; Hydrogen storage ; Proton exchange membrane fuel cell ; Bar (unit) ; Materials science ; Artificial neural network ; Computer science ; Process engineering ; Membrane ; Chemical engineering ; Chemistry ; Thermodynamics ; Engineering ; Artificial intelligence ; Physics ; Organic chemistry Metal-Organic Frameworks: Synthesis and Applications ; Hydrogen Storage and Materials ; Fuel Cells and Related Materials
Authors: Chenqing Hua | Sitao Luan | Minkai Xu | Rex Ying | Jie Fu | Stefano Ermon | Doina Precup
Source: arXiv (Cornell University) (preprint, 2023-04-28)
Field: Materials Science — Materials Chemistry

MUDiff: Unified Diffusion for Complete Molecule Generation Molecule generation is a very important practical problem, with uses in drug discovery and material design, and AI methods promise to provide useful solutions. However, existing methods for molecule generation focus either on 2D graph structure or on 3D geometric structure, which is not sufficient to represent a complete molecule as 2D graph captures mainly topology while 3D geometry captures mainly spatial atom arrangements. Combining these representations is essential to better represent a molecule. In this paper, we present a new model for generating a comprehensive representation of molecules, including atom features, 2D discrete molecule structures, and 3D continuous molecule coordinates, by combining discrete and continuous diffusion processes. The use of diffusion processes allows for capturing the probabilistic nature of molecular processes and exploring the effect of different factors on molecular structures. Additionally, we propose a novel graph transformer architecture to denoise the diffusion process. The transformer adheres to 3D roto-translation equivariance constraints, allowing it to learn invariant atom and edge representations while preserving the equivariance of atom coordinates. This transformer can be used to learn molecular representations robust to geometric transformations. We evaluate the performance of our model through experiments and comparisons with existing methods, showing its ability to generate more stable and valid molecules. Our model is a promising approach for designing stable and diverse molecules and can be applied to a wide range of tasks in molecular modeling. Computer science ; Graph ; Topology (electrical circuits) ; Molecule ; Probabilistic logic ; Representation (politics) ; Theoretical computer science ; Biological system ; Algorithm ; Mathematics ; Artificial intelligence ; Chemistry Machine Learning in Materials Science ; Computational Drug Discovery Methods ; Protein Structure and Dynamics