jablonkagroup/rise_ai_scientists huggingface dataset:
Authors: Anna Song
Source: Journal of Mathematical Imaging and Vision (article, 2021-08-19)
Field: Materials Science — Materials Chemistry

Generation of Tubular and Membranous Shape Textures with Curvature Functionals Abstract Tubular and membranous shapes display a wide range of morphologies that are difficult to analyze within a common framework. By generalizing the classical Helfrich energy of biomembranes, we model them as solutions to a curvature optimization problem in which the principal curvatures may play asymmetric roles. We then give a novel phase-field formulation to approximate this geometric problem, and study its Gamma-limsup convergence. This results in an efficient GPU algorithm that we validate on well-known minimizers of the Willmore energy; the software for the implementation of our algorithm is freely available online. Exploring the space of parameters reveals that this comprehensive framework leads to a wide continuum of shape textures. This first step towards a unifying theory will have several implications, in biology for quantifying tubular shapes or designing bio-mimetic scaffolds, but also in computer graphics, materials science, or architecture. Willmore energy ; Curvature ; Principal curvature ; Computer graphics ; Geometric shape ; Energy functional ; Convergence (economics) ; Computer science ; Software ; Shape optimization ; Mathematics ; Geometry ; Mean curvature ; Algorithm ; Computer graphics (images) ; Finite element method ; Physics ; Mathematical analysis Solidification and crystal growth phenomena ; Advanced Mathematical Modeling in Engineering ; Cellular Mechanics and Interactions
Authors: PROMA MUKHERJEE | D Chakraborty | Prithviraj Chakraborty | Bhupendra Shrestha | Nihar Ranjan Bhuyan
Source: Asian Journal of Pharmaceutical and Clinical Research (article, 2021-09-07)
Field: Chemistry — Analytical Chemistry

DIFFERENT ULTRAVIOLET SPECTROSCOPIC METHODS: A RETROSPECTIVE STUDY ON ITS APPLICATION FROM THE VIEWPOINT OF ANALYTICAL CHEMISTRY In routine practice, some simple and rapid analytical methods are needed for the assessment of formulations containing multiple elements, complex matrix system and for biotherapeutic products. There are several methods available for ultraviolet (UV) spectrophotometry that rely on the concept of absorbance difference, absorbance spectra, and additivity, also included in the list are simultaneous equation method, Q-absorbance ratio method, derivative spectrophotometry, ratio derivative spectra, successive ratio-derivative spectra, absorption and absorptivity factor method, and difference spectrophotometry along with multivariate chemometric methods. In this review, emphasis has been given to the theories, mathematical context, advantages, and disadvantages along with the vast applications of UV spectrophotometry. The findings further highlighted that for the analysis of drugs, UV spectrophotometry remains as one of the most simple, cheap, and promising option for routine practice in the field of pharmaceuticals. Absorbance ; Spectrophotometry ; Chemistry ; Molar absorptivity ; Ultraviolet visible spectroscopy ; Context (archaeology) ; Analytical Chemistry (journal) ; Ultraviolet ; Second derivative ; Chromatography ; Optics ; Organic chemistry ; Mathematics ; Physics Analytical Methods in Pharmaceuticals ; Spectroscopy and Chemometric Analyses ; Analytical Chemistry and Chromatography
Authors: Roland Gillen
Source: physica status solidi (b) (article, 2021-03-30)
Field: Materials Science — Materials Chemistry

Interlayer Excitonic Spectra of Vertically Stacked MoSe<sub>2</sub>/WSe<sub>2</sub> Heterobilayers The optical spectra of vertically stacked / heterostructures contain additional “interlayer” excitonic peaks that are absent in the individual monolayer materials and exhibit a significant spatial charge separation in out‐of‐plane direction. A many‐body perturbation theory approach is used to simulate the excitonic spectra of / heterobilayers with three stacking orders, considering both momentum‐direct and momentum‐indirect excitons. The small oscillator strengths and the optical responses of the interlayer excitons are significantly stacking‐dependent and give rise to high radiative lifetimes in the range of 5–200 ns at low temperature for the “bright” interlayer excitons. Solving the finite‐momentum Bethe–Salpeter Equation (BSE), the lowest energy excitation is predicted to be an exciton over the fundamental indirect band gap, with a binding energy of 220 meV. However, in agreement with recent magneto‐optics experiments and previous theoretical studies, the simulations of the effective excitonic g ‐factors suggest that the low energy momentum‐indirect excitons are not experimentally observed. The existence of “interlayer” C excitons with significant exciton binding energies and optical oscillator strengths is further revealed, which are analogous to the prominent band nesting excitons in mono‐ and few‐layer transition‐metal dichalcogenides. Materials science ; Spectral line ; Condensed matter physics ; Physics 2D Materials and Applications ; Perovskite Materials and Applications ; Chalcogenide Semiconductor Thin Films
Authors: Anne Ruffing | Stephen M. Anthony | Lucas Marshall Strickland | Ian Lubkin | Carter R. Dietz
Source: Frontiers in Plant Science (article, 2021-02-16)
Field: Chemistry — Analytical Chemistry

Identification of Metal Stresses in Arabidopsis thaliana Using Hyperspectral Reflectance Imaging Industrial accidents, such as the Fukushima and Chernobyl disasters, release harmful chemicals into the environment, covering large geographical areas. Natural flora may serve as biological sensors for detecting metal contamination, such as cesium. Spectral detection of plant stresses typically employs a few select wavelengths and often cannot distinguish between different stress phenotypes. In this study, we apply hyperspectral reflectance imaging in the visible and near-infrared along with multivariate curve resolution (MCR) analysis to identify unique spectral signatures of three stresses in <i>Arabidopsis thaliana</i>: salt, copper, and cesium. While all stress conditions result in common stress physiology, hyperspectral reflectance imaging and MCR analysis produced unique spectral signatures that enabled classification of each stress. As the level of potassium was previously shown to affect cesium stress in plants, the response of <i>A. thaliana</i> to cesium stress under variable levels of potassium was also investigated. Increased levels of potassium reduced the spectral response of <i>A. thaliana</i> to cesium and prevented changes to chloroplast cellular organization. While metal stress mechanisms may vary under different environmental conditions, this study demonstrates that hyperspectral reflectance imaging with MCR analysis can distinguish metal stress phenotypes, providing the potential to detect metal contamination across large geographical areas. Hyperspectral imaging ; Arabidopsis thaliana ; Contamination ; Environmental science ; Remote sensing ; Reflectivity ; Botany ; Environmental chemistry ; Biological system ; Biology ; Chemistry ; Geology ; Ecology ; Optics ; Physics Spectroscopy and Chemometric Analyses ; Isotope Analysis in Ecology ; Spectroscopy Techniques in Biomedical and Chemical Research
Authors: Jiazheng Lu | Jianping Hu | Zhen Fang | Xinhan Qiao | Zhijin Zhang
Source: Energies (article, 2021-11-09)
Field: Materials Science — Materials Chemistry

Electric Field Distribution and AC Breakdown Characteristics of Polluted Novel Lightning Protection Insulator under Icing Conditions As a result of lightning strikes, pollution, and ice, overhead distribution wires might be short-circuited and trip. As a result, researchers have developed a new lightning protection composite insulator. There is still a need to test its pollution and icing performance. Based on the finite element and field test method, this paper studies the electric field distribution and AC (Alternating Current) breakdown characteristics of polluted novel lightning protection insulators under icing conditions. Firstly, the finite element calculated results show that this novel insulator’s electric field distribution is different from that of a conventional insulator. The locations with sizeable electric fields are located in the insulation section, and the electric field in the arrester section is tiny. In addition, when the insulator surface is covered with ice, there is an increase in the electric field along the surface and pin electrodes. Compared with the dry conditions, when there is an ice layer and icicle, electric field peaks increase by 48.85% and 46.08%, respectively. Secondly, the test results show that there are three types of arc paths in different pollution levels. The arc paths are related to ESDD (equivalent salt deposit density) under icing conditions. Uf shows a downward trend with increased pollution levels, and the maximum flashover voltage is 2.70 times more than the minimum. Finally, four fitting methods are proposed in this paper. After comparing the goodness of fit of different functions, the quadratic function and negative power function with the constant term are recommended as empirical formulas for calculating flashover voltage of novel insulators under icing conditions in different pollution levels. The research results of this paper have a specific guiding role for the selection of the external insulation of transmission lines and structural optimization of novel insulators. Insulator (electricity) ; Icing ; Electric field ; Arc flash ; Lightning (connector) ; Voltage ; Lightning arrester ; Overhead line ; Electric power transmission ; Environmental science ; Electrical engineering ; Materials science ; Engineering ; Structural engineering ; Meteorology ; Physics ; Power (physics) High voltage insulation and dielectric phenomena ; Icing and De-icing Technologies ; Lightning and Electromagnetic Phenomena
Authors: Adrián Esteban-Arranz | Marı́a Pérez-Cadenas | V. Muñoz-Andrés | A. Guerrero-Ruı́z
Source: Environmental Pollution (article, 2021-04-16)
Field: Materials Science — Materials Chemistry

Evaluation of graphenic and graphitic materials on the adsorption of Triton X-100 from aqueous solution Graphene ; Adsorption ; Graphite ; Aqueous solution ; Materials science ; Oxide ; Chemical engineering ; Diffusion ; Specific surface area ; Particle size ; Chemistry ; Nanotechnology ; Composite material ; Organic chemistry ; Catalysis ; Metallurgy Graphene research and applications ; Graphene and Nanomaterials Applications ; Adsorption and biosorption for pollutant removal
Authors: P. Utpalla | Jaideep Mor | Sandeep Kumar Sharma | Jitendra Bahadur | P.K. Pujari
Source: Journal of Solid State Chemistry (article, 2021-11-17)
Field: Chemistry — Inorganic Chemistry

Pore interconnectivity and surface accessibility in stiffened mixed linker MOFs: An investigation using variable energy positron spectroscopy Permeance ; Membrane ; Interconnectivity ; Selectivity ; Chemical engineering ; Materials science ; Chemistry ; Analytical Chemistry (journal) ; Diffusion ; Organic chemistry ; Thermodynamics ; Permeation Metal-Organic Frameworks: Synthesis and Applications ; Muon and positron interactions and applications ; Membrane Separation and Gas Transport
Authors: Mohammed A. El‐Hashemy | Nasser F. Alotaibi
Source: Biomass Conversion and Biorefinery (article, 2021-04-14)
Field: Materials Science — Materials Chemistry

Purification of benzene-laden air by static adsorption of benzene onto activated carbon prepared from Diplotaxis acris biomass Thermogravimetric analysis ; Benzene ; Adsorption ; Activated carbon ; Scanning electron microscope ; Fourier transform infrared spectroscopy ; Analytical Chemistry (journal) ; Langmuir adsorption model ; Specific surface area ; Materials science ; Chemistry ; Nuclear chemistry ; Chemical engineering ; Chromatography ; Catalysis ; Organic chemistry ; Composite material Catalytic Processes in Materials Science ; Adsorption and biosorption for pollutant removal ; Carbon Dioxide Capture Technologies
Authors: Andrew Cassidy | Mads R. V. Jørgensen | Artur Glavic | Valeria Lauter | Oksana Plekan | D. Field
Source: Chemical Communications (article, 2021-01-01)
Field: Materials Science — Materials Chemistry

A mechanism for ageing in a deeply supercooled molecular glass Measurements of the decay of electric fields, formed spontaneously within vapour-deposited films of cis-methyl formate, provide the first direct assessment of the energy barrier to secondary relaxation in a molecular glass. At temperatures far below the glass transition temperature, the mechanism of relaxation is shown to be through hindered molecular rotation. Magnetically-polarised neutron scattering experiments exclude diffusion, which is demonstrated to take place only close to the glass transition temperature. Supercooling ; Ageing ; Mechanism (biology) ; Materials science ; Chemical physics ; Chemistry ; Thermodynamics ; Philosophy ; Physics ; Epistemology ; Biology Material Dynamics and Properties ; Liquid Crystal Research Advancements ; Glass properties and applications
Authors: Hang Yu | Jie Yang
Source: Polymers (article, 2021-07-17)
Field: Materials Science — Polymers and Plastics

Predictions of Moisture Diffusion Behavior of Cellulose-Fiber-Reinforced Plain Weave Epoxy Composites Cellulose-fiber-reinforced plain weave composites absorb lots of water from humid environments because of their inherent susceptibility to moisture. Moisture absorption experiments with cellulose fiber plain weave composites have been reported by some researchers; however, few theoretical studies have been performed to date to predict their moisture diffusion behavior. In this paper, the moisture diffusion behavior of cellulose-fiber-reinforced plain weave composite is predicted using a novel superposition method considering its microweave pattern. The overall moisture uptake of the composite is treated as moisture absorption superposition of the fiber bundles part, resin part, undulated fiber bundles and resin-rich part in the unit cell. The moisture diffusion of the undulated fiber bundles and resin-rich part is more complicated than the other parts; thus, a solution for a unique three-phase diffusion problem is used to solve this special moisture diffusion issue. Both finite element analysis and experiments are carried out to validate the proposed approach, with the results showing that the predictions can effectively characterize the moisture diffusion behavior of cellulose-fiber-reinforced plain weave composites. Composite material ; Moisture ; Materials science ; Fiber ; Plain weave ; Diffusion ; Cellulose fiber ; Composite number ; Cellulose ; Epoxy ; Absorption of water ; Natural fiber ; Superposition principle ; Glass fiber ; Mathematics ; Chemical engineering ; Engineering ; Yarn Natural Fiber Reinforced Composites ; Mechanical Behavior of Composites ; Textile materials and evaluations
Authors: W. Ou | W.M. Arnoldbik | K. Li | P. Rindt | T.W. Morgan
Source: Nuclear Fusion (article, 2021-10-22)
Field: Materials Science — Materials Chemistry

Deuterium retention and removal in liquid lithium determined by in situ NRA in Magnum-PSI Abstract In this work, Li-filled 3D-printed porous tungsten samples were exposed to deuterium (D) plasma in Magnum-PSI with a wide ion flux from 4 × 10 22 to 1.5 × 10 24 m −2 s −1 and with a corresponding wide temperature range from below Li melting point (180.5 °C) to above Li deuteride (LiD) melting point (∼690 °C). The formation, decomposition and melting of LiD have been directly observed in the experiment via infra-red thermometry and visually post-mortem while still in vacuo, and correlated to the D retained content. The LiD formation was characterized by a solid precipitate layer formed on the surface with high emissivity (0.6–0.9) characterized by a blue or dark blue color after exposure. The melting of Li–LiD layer was found to occur close to the temperature predicted by Li–LiD phase diagram. In situ nuclear reaction analysis (NRA) was applied to perform the measurement of D retained in Li samples immediately after exposure without breaking the vacuum. D depth profiles were determined by NRA, in which the highest D concentration (15–45 at.%) was found in the top several micrometers and decreases with depth to low levels (&lt;5%) within 5–30 μ m. No pure LiD layer was found on the sample surfaces, however a D concentration close to 50 at.% was observed on a Li-D co-deposited layer on the clamping ring in some cases. The experiments also indicate that the D retained increases with increasing temperature until ∼500 °C. At temperatures beyond ∼500 °C the dissociation of LiD starts to dominate and the deuterium retention started to decrease. Overall, D retained fraction for all cases was found to be below ∼2%, which is significantly different from literatures where full uptake has been suggested. A 1D reaction–diffusion (RD) model based on D diffusion and chemical reactions with Li has been built. D depth profiles from the RD modelling can roughly match that from NRA measurement and a low D retained fraction below ∼2% was also indicated by the model. The model can also help explain the relationship between D retained and the surface temperature and fluence. After D plasma exposure, either helium or H plasma was utilized to remove the retained D in Li and both were proved to be effective and the removal efficiency can be as high as 96% above 420 °C. Materials science ; Tungsten ; Deuterium ; Nuclear reaction analysis ; Analytical Chemistry (journal) ; Melting point ; Lithium (medication) ; Atmospheric temperature range ; Ion ; Chemistry ; Chromatography ; Composite material Fusion materials and technologies ; Nuclear Materials and Properties ; Hydrogen Storage and Materials
Authors: Fathi Hamed Elghareeb | E. M. Kandil | M. Abou-Elzahab | Mohamed Abdelmoteleb | Mohamed Ahmed Abozeid
Source: RSC Advances (article, 2021-01-01)
Field: Chemistry — Organic Chemistry

Rigid 3D-spiro chromanone as a crux for efficient antimicrobial agents: synthesis, biological and computational evaluation The development of new and effective antimicrobial agents with novel chemical skeletons and working mechanisms is highly desirable due to the increased number of resistant microbes. Different new compounds based upon a 3D-spiro chromanone scaffold such as Mannich bases 2 and 3 in addition to azo dye 4 were synthesized. Besides, the condensation reactions of the hydrazide-spiro chromanone 8 with different ketonic reagents led to the synthesis of pyrazoles (9 & 10) and anils (11 & 13). Moreover, the methoxyl substituted spiro chromanone 14 was condensed with different hydrazines and hydrazides to give the corresponding hydrazones 15-18 in up to 85% yields. The condensation of the hydrazone 18 with salicylaldehyde yielded coumarinyl spiro chromanone 19 in an excellent yield, whereas its reaction with benzaldehyde followed by hydrazine afforded aminopyrazole derivative 21 in 82% yield. The antimicrobial evaluation suggested that hydrazide 8 has a substantial activity against different microbes (<i>S. aureus</i>: <i>D</i> = 22 mm, MIC = 1.64 μM; <i>E. coli</i>: <i>D</i> = 19 mm, MIC = 1.64 μM; <i>C. albicans</i>: <i>D</i> = 20 mm, MIC = 6.57 μM). Moreover, promising antimicrobial activities were observed for azo dye 4 (<i>D</i> = 13-19 mm, MIC = 5.95-11.89 μM), hydrazone 17 (<i>D</i> = 17-23 mm, MIC = 1.88-3.75 μM), and aminopyrazole 21 (<i>D</i> = 14-19 mm, MIC = 2.24-8.98 μM). The molecular docking revealed that compounds 4, 8, 17, and 21 had good to high binding affinities with different microbial targets such as penicillin-binding proteins (-7.4 to -9.9 kcal), DNA gyrase (-7.8 to -9.0 kcal), lanosterol 14-alpha demethylase (-8.2 to -11.2 kcal), and <i>exo</i>-beta-1,3-glucanase (-8.2 to -11.9 kcal). The QSAR analysis ascertained a good correlation between the antimicrobial activity of 3D-spiro chromanone derivatives and their structural and/or physicochemical parameters. Hydrazone ; Hydrazide ; Antimicrobial ; Chemistry ; Reagent ; Benzaldehyde ; Yield (engineering) ; Hydrazine (antidepressant) ; Salicylaldehyde ; Combinatorial chemistry ; Stereochemistry ; Medicinal chemistry ; Nuclear chemistry ; Organic chemistry ; Chromatography Synthesis and biological activity ; Multicomponent Synthesis of Heterocycles ; Click Chemistry and Applications
Authors: Maarten K. Jongkind | Miguel Rivera‐Torrente | Nikolaos Nikolopoulos | Bert M. Weckhuysen
Source: Chemistry - A European Journal (article, 2021-01-29)
Field: Chemistry — Inorganic Chemistry

Influence of Pore Structure and Metal‐Node Geometry on the Polymerization of Ethylene over Cr‐Based Metal–Organic Frameworks Metal-organic frameworks (MOFs) have received increasing interest as solid single-site catalysts, owing to their tunable pore architecture and metal node geometry. The ability to exploit these modulators makes them prominent candidates for producing polyethylene (PE) materials with narrow dispersity index (Ð) values. Here a study is presented in which the ethylene polymerization properties, with Et<sub>2</sub> AlCl as activator, of three renowned Cr-based MOFs, MIL-101(Cr)-NDC (NDC=2,6-dicarboxynapthalene), MIL-53(Cr) and HKUST-1(Cr), are systematically investigated. Ethylene polymerization reactions revealed varying catalytic activities, with MIL-101(Cr)-NDC and MIL-53(Cr) being significantly more active than HKUST-1(Cr). Analysis of the PE products revealed large Ð values, demonstrating that polymerization occurs over a multitude of active Cr centers rather than a singular type of Cr site. Spectroscopic experiments, in the form of powder X-ray diffraction (pXRD), UV/Vis-NIR diffuse reflectance spectroscopy (DRS) and CO probe molecule Fourier transform infrared (FTIR) spectroscopy corroborated these findings, indicating that indeed for each MOF unique active sites are generated, however without alteration of the original oxidation state. Furthermore, the pXRD experiments indicated that one major prerequisite for catalytic activity was the degree of MOF activation by the Et<sub>2</sub> AlCl co-catalyst, with the more active materials portraying a larger degree of activation. Polymerization ; Dispersity ; Catalysis ; Metal-organic framework ; Materials science ; Powder diffraction ; Fourier transform infrared spectroscopy ; Ethylene ; Metal ; Diffuse reflectance infrared fourier transform ; Infrared spectroscopy ; Molecule ; Chemical engineering ; Polymer chemistry ; Physical chemistry ; Chemistry ; Crystallography ; Organic chemistry ; Polymer ; Photocatalysis ; Composite material ; Metallurgy ; Adsorption Metal-Organic Frameworks: Synthesis and Applications ; Covalent Organic Framework Applications ; Membrane Separation and Gas Transport