jablonkagroup/rise_ai_scientists huggingface dataset:
Authors: Ilya Kuprov | Laura Morris | John Glushka | James H. Prestegard
Source: Journal of Magnetic Resonance (article, 2020-12-13)
Field: Chemistry — Spectroscopy

Using molecular dynamics trajectories to predict nuclear spin relaxation behaviour in large spin systems Molecular dynamics ; Spin (aerodynamics) ; Relaxation (psychology) ; Dynamics (music) ; Chemical physics ; Nuclear magnetic resonance ; Materials science ; Physics ; Statistical physics ; Chemistry ; Computational chemistry ; Thermodynamics ; Medicine Advanced NMR Techniques and Applications ; Spectroscopy and Quantum Chemical Studies ; Protein Structure and Dynamics
Authors: Shunli Ma | Yan Wang | Xinyu Chen | Tianxiang Wu | Xi Wang | Hongwei Tang | Yuting Yao | Hao Yu | Yaochen Sheng | Jingyi Ma | Junyan Ren | Wenzhong Bao
Source: IEEE Access (article, 2020-01-01)
Field: Materials Science — Materials Chemistry

Analog Integrated Circuits Based on Wafer-Level Two-Dimensional MoS<sub>2</sub> Materials With Physical and SPICE Model In this article, accurate physical and SPICE model of wafer-level monolayer molybdenum disulfide (MoS <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> ) device are developed to guide the devices and circuits design, which is the foundation of high-performance analog chip design. Moreover, the proposed model considers the non-ideality of thin films and the influence of Schottky contact with higher accuracy. The mean percentage error (MPE) of the physical model simulation and measurement results is 4.49%. Based on the SPICE model implemented in this article, the amplifier circuit and current amplifying circuits are implemented to verify the manufacturing process and accuracy of the device models, which shows the MoS <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> is potential material to realize industrial applications. The MPE of the SPICE model simulation and measurement results is within 7.00% which can be utilized for our analog circuit design. Spice ; Computer science ; Electronic engineering ; Electronic circuit ; Amplifier ; Integrated circuit ; CMOS ; Electrical engineering ; Engineering 2D Materials and Applications ; Advanced Memory and Neural Computing ; Perovskite Materials and Applications
Authors: P. Chakraborty | Christine Guéneau | Alain Chartier
Source: Solid State Ionics (article, 2020-11-04)
Field: Materials Science — Materials Chemistry

Modelling of plutonium diffusion in (U,Pu)O2±x mixed oxide MOX fuel ; Plutonium ; Oxide ; Mixed oxide ; Chemistry ; Nuclear engineering ; Radiochemistry ; Materials science ; Metallurgy ; Engineering Nuclear Materials and Properties ; Nuclear reactor physics and engineering ; Radioactive element chemistry and processing
Authors: Laurence Cherfils | Hussein Fakih | Maurizio Grasselli | Alain Miranville
Source: ESAIM Mathematical Modelling and Numerical Analysis (article, 2020-04-21)
Field: Materials Science — Materials Chemistry

A convergent convex splitting scheme for a nonlocal Cahn–Hilliard–Oono type equation with a transport term We devise a first-order in time convex splitting scheme for a nonlocal Cahn–Hilliard–Oono type equation with a transport term and subject to homogeneous Neumann boundary conditions. However, we prove the stability of our scheme when the time step is sufficiently small, according to the velocity field and the interaction kernel. Furthermore, we prove the consistency of this scheme and the convergence to the exact solution. Finally, we give some numerical simulations which confirm our theoretical results and demonstrate the performance of our scheme not only for phase separation, but also for crystal nucleation, for several choices of the interaction kernel. Mathematics ; Term (time) ; Regular polygon ; Convergence (economics) ; Cahn–Hilliard equation ; Applied mathematics ; Allen–Cahn equation ; Boundary (topology) ; Type (biology) ; Mathematical analysis ; Stability (learning theory) ; Kernel (algebra) ; Scheme (mathematics) ; Boundary value problem ; Neumann boundary condition ; Partial differential equation ; Pure mathematics ; Geometry ; Physics Solidification and crystal growth phenomena ; Advanced Mathematical Modeling in Engineering ; Fluid Dynamics and Thin Films
Authors: Patrick D. Zarnas | Rémi Dingreville | Brittany Muntifering | Khalid Hattar | Brad Boyce | Jianmin Qu
Source: Advanced Modeling and Simulation in Engineering Sciences (article, 2020-02-19)
Field: Materials Science — Materials Chemistry

Statistical analysis of the interaction between irradiation-induced defects and triple junctions Abstract By using a generalized, spatially resolved rate theory, we systematically studied the irradiation-induced diffusion and segregation of point defects near triple junctions. Our model captured not only the formation, growth, and recombination of point defects but also the interaction of these defects with pre-existing defects. We coupled the stress field of the triple junction with defect diffusion via a modified chemical potential. The residual stress fields of grain boundaries and triple junctions are modeled via disclination mechanics theory. By assessing the behavior of 144 triple junctions with vacancy and interstitial defects, we correlated defect-sink efficiencies with key characteristics of triple junctions. For vacancies, the geometric configuration of triple junctions dominated sink efficiency, suggesting that equiaxed grains would resist the accumulation of vacancies more than elongated grains. For interstitials, the sink density of the grain boundaries composing the triple junctions dominated sink efficiency. Hence, the interstitial concentration may be managed by adjusting the structure of the grain boundaries. Overall, we illustrated the complex coupling between pre-existing defects and radiation-induced defects through interaction of their stress fields. This theoretical framework provides an efficient tool to rapidly assess defect management in microstructures. Triple junction ; Materials science ; Grain boundary ; Crystallographic defect ; Vacancy defect ; Irradiation ; Condensed matter physics ; Triple point ; Molecular physics ; Microstructure ; Chemical physics ; Optoelectronics ; Composite material ; Physics ; Thermodynamics Fusion materials and technologies ; Nuclear materials and radiation effects ; Nuclear Materials and Properties
Authors: Yu‐Ren Liao | Li-Shian Shi | Ming‐Jai Su | An‐Sheng Lee | Kuo‐Hsiung Lee | Tian‐Shung Wu | Han‐Dong Sun | Sheng‐Chu Kuo | Amooru G. Damu | Ping‐Chung Kuo
Source: Figshare (article, 2020-11-04)
Field: Materials Science — Biomaterials

Cardiac Glycosides from Antiaris toxicaria with Potent Cardiotonic Activity An ethanolic extract of Antiaris toxicaria trunk bark showed potent in vitro cardiotonic effect on isolated guinea pig atria. Bioassay-guided fractionation of the extract led to identification of 9 new cardiac glycosides (1–9, named antiarosides A-I), antiarotoxinin A (10), and 18 known compounds. Their structures were established using MS and NMR spectroscopic studies, including homonuclear and heteronuclear correlation experiments. The ability of these cardiotonic compounds to produce positive inotropic action and their safety indexes were examined in comparison with those of ouabain, a classical inhibitor of Na+/K+-ATPase. Malayoside (23) was nearly equipotent and had a similar safety index to ouabain in guinea pig atria. However, the maximal positive inotropic effect and safety index of 23 in papillary muscle were better than those of ouabain. An electrophysiological recording showed that 23 inhibited sodium pump current in a concentration-dependent manner. Glycoside ; Chemistry ; Traditional medicine ; Pharmacology ; Medicine ; Stereochemistry Phytochemistry and Bioactive Compounds ; Natural product bioactivities and synthesis ; Phytochemical Studies and Bioactivities
Authors: Mauricio Oberti | Iosif I. Vaisman
Source: Proteins Structure Function and Bioinformatics (article, 2020-06-14)
Field: Chemistry — Spectroscopy

<scp>cnnAlpha</scp>: Protein disordered regions prediction by reduced amino acid alphabets and convolutional neural networks Intrinsically disordered regions (IDR) play an important role in key biological processes and are closely related to human diseases. IDRs have great potential to serve as targets for drug discovery, most notably in disordered binding regions. Accurate prediction of IDRs is challenging because their genome wide occurrence and a low ratio of disordered residues make them difficult targets for traditional classification techniques. Existing computational methods mostly rely on sequence profiles to improve accuracy which is time consuming and computationally expensive. This article describes an ab initio sequence-only prediction method-which tries to overcome the challenge of accurate prediction posed by IDRs-based on reduced amino acid alphabets and convolutional neural networks (CNNs). We experiment with six different 3-letter reduced alphabets. We argue that the dimensional reduction in the input alphabet facilitates the detection of complex patterns within the sequence by the convolutional step. Experimental results show that our proposed IDR predictor performs at the same level or outperforms other state-of-the-art methods in the same class, achieving accuracy levels of 0.76 and AUC of 0.85 on the publicly available Critical Assessment of protein Structure Prediction dataset (CASP10). Therefore, our method is suitable for proteome-wide disorder prediction yielding similar or better accuracy than existing approaches at a faster speed. Convolutional neural network ; Computer science ; Artificial intelligence ; Sequence (biology) ; Reduction (mathematics) ; Pattern recognition (psychology) ; Class (philosophy) ; Intrinsically disordered proteins ; Proteome ; Machine learning ; Computational biology ; Data mining ; Bioinformatics ; Chemistry ; Mathematics ; Biology Advanced Proteomics Techniques and Applications ; Protein Structure and Dynamics ; Machine Learning in Bioinformatics
Authors: Gökhan Koçak | Cansel Tuncer | Vural Bütün
Source: Hacettepe Journal of Biology and Chemistry (article, 2020-10-15)
Field: Chemistry — Organic Chemistry

Stimuli-Responsive Polymers Providing New Opportunities for Various Applications Stimuli-responsive polymers significantly change their physical or chemical properties when there is a small change in the conditions of their environments. Depending on the changes on conditions, they can self-assemble to form various nanosized structures having important usages in different fields. In this review, we report an analysis of some of the recent literatures on the basic subjects such as the architectures of different environmentally sensitive polymers, their classifications according to susceptibility and applications in various areas. During the last two decades, there have been great reports in the strategies for the preparation of novel stimuli-responsive polymers and/or polymeric materials which are suitable for various applications including materials science, nanotechnology, biotechnology, colloid and surface science, etc. In order to make this very broad polymer type more understandable to readers, basic concepts/topics are generally schematized. Furthermore, the strategies that can be followed in the production of these materials are tried to be given at a sufficient level. Nanotechnology ; Polymer ; Computer science ; Biochemical engineering ; Data science ; Materials science ; Engineering Advanced Polymer Synthesis and Characterization ; biodegradable polymer synthesis and properties ; Synthesis and properties of polymers
Authors: Joana Salta | Fabian F. Arp | Christian Kühne | Hans‐Ulrich Reißig
Source: European Journal of Organic Chemistry (article, 2020-11-17)
Field: Chemistry — Organic Chemistry

Multivalent 1,2,3‐Triazole‐Linked Carbohydrate Mimetics by Huisgen–Meldal‐Sharpless Cycloadditions of an Azidopyran Starting from an enantiopure 3‐azido‐substituted pyran derivative and various oligo‐alkynes a series of multivalent 1,2,3‐triazole‐linked carbohydrate mimetics was synthesized. The copper‐catalyzed Huisgen–Meldal‐Sharpless cycloaddition (CuAAC) served as key coupling reaction. Cu/C in the presence of triethylamine proved to be a good catalytic system in most cases. Tri‐, tetra‐, hexa‐, and octavalent compounds with typical rigid or flexible core units were prepared. The most complex compound contains a C 60 ‐fullerene center leading to a dodecavalent carbohydrate mimetic. Only a few of the multivalent target compounds could be converted into pure O ‐sulfated derivatives that are required for their evaluation as L‐ and P‐selectin ligands. Nevertheless, preliminary experiments suggest that the dodecavalent C 60 ‐derived compound may be a promising ligand of these biologically important proteins with IC 50 values in the low nanomolar range. Chemistry ; Cycloaddition ; Triazole ; Click chemistry ; Enantiopure drug ; Combinatorial chemistry ; Triethylamine ; Azide ; Pyran ; Carbohydrate ; Stereochemistry ; Ligand (biochemistry) ; Catalysis ; Organic chemistry ; Enantioselective synthesis Click Chemistry and Applications ; Chemical Synthesis and Analysis ; Peptidase Inhibition and Analysis
Authors: Yukiya Kyoden | Takayuki Ishida
Source: RSC Advances (article, 2020-01-01)
Field: Materials Science — Electronic, Optical and Magnetic Materials

An indication of spin-transition accompanied by an order-disorder structural transformation in [Ni(phpyNO)<sub>2</sub>(NCS)<sub>2</sub>] (phpyNO = <i>tert</i>-butyl 5-phenyl-2-pyridyl nitroxide) Reaction of nickel(ii) thiocyanate and <i>tert</i>-butyl 5-phenyl-2-pyridyl nitroxide (phpyNO) afforded a 2p-3d-2p heterospin triad [Ni(phpyNO)<sub>2</sub>(NCS)<sub>2</sub>]. The compound crystallizes in the orthorhombic <i>Pbcn</i> space group. The whole molecule is crystallographically independent. The torsion angles around Ni-O-N-C<sub>2py</sub> are 26.8(4) and 27.3(4)° at 400 K, indicating appreciable orbital overlaps of the radical π* and nickel(ii) 3d <sub><i>x</i> <sup>2</sup>-<i>y</i> <sup>2</sup></sub> /3d <sub><i>z</i> <sup>2</sup></sub> orbitals. In a low-temperature region, the torsion was enhanced, and the space group changed to monoclinic <i>P</i>2<sub>1</sub>/<i>c</i> with a doubled asymmetric unit volume. The <i>χ</i> <sub>m</sub> <i>T</i> value was practically null below <i>ca.</i> 140 K and, on heating to 400 K, gradually increased and reached 1.30 cm<sup>3</sup> K mol<sup>-1</sup>. A van't Hoff analysis suggests a spin transition at <i>T</i> <sub>1/2</sub> = 530(20) K. Density functional theory calculation reproduced ground <i>S</i> <sub>total</sub> = 0 with singlet-triplet gaps of 910 and 1263 K for the 140 K structure, and the gap was reduced to 297 K at 400 K. Consequently, the present compound can be considered as an incomplete spin-crossover material, as a result of <i>T</i> <sub>1/2</sub> located above the experimental temperature window. Nitroxide mediated radical polymerization ; Spin (aerodynamics) ; Order (exchange) ; Crystallography ; Chemistry ; Transformation (genetics) ; Transition metal ; Materials science ; Physics ; Organic chemistry ; Thermodynamics ; Catalysis ; Polymer Magnetism in coordination complexes ; Lanthanide and Transition Metal Complexes ; Electron Spin Resonance Studies
Authors: Ugo Azzena | Massimo Carraro | Martina Corrias | Rosella Crisafulli | Lidia De Luca | Silvia Gaspa | Luca Nuvoli | Salvatore Pintus | Luisa Pisano | Riccardo Polese | Michela Sanna | G Satta | Nina Senes | Luigi Urtis | Sebastiano Garroni
Source: Catalysts (article, 2020-09-24)
Field: Chemistry — Organic Chemistry

Ammonium Salts Catalyzed Acetalization Reactions in Green Ethereal Solvents Cyclopentyl methyl ether and 2-methyltetrahydrofuran, low impact ethereal solvents forming a positive azeotrope with water, were successfully employed as solvents in the synthesis of a variety of acetals carried out under Dean–Stark conditions in the presence of heterogeneous acidic catalysts. Under these conditions, ammonium salts, either as such or supported on SiO2, performed better or equally well than widely employed homogeneous and heterogeneous acidic catalysts such as p-toluenesulfonic acid, Amberlyst 15®, or Montmorillonite K10. Several examples highlight the advantage of tuning the relative acidities of ammonium salts by appropriately selecting the counterion. Within one of these examples, our protocol clearly outweighs the classic p-toluenesulfonic acid/toluene protocol in terms of chemoselectivity. Silica-supported catalysts were characterized by SEM, TEM, and FTIR spectroscopies, as well as by N2 physisorption. Such a characterization reveals an even distribution of ammonium salts on silica, thus confirming the formation of expected catalytic supports. Catalysis ; Chemistry ; p-Toluenesulfonic acid ; Toluene ; Organic chemistry ; Ammonium ; Beckmann rearrangement ; Counterion ; Heterogeneous catalysis ; Azeotrope ; Ion Chemical Synthesis and Reactions ; Chemistry and Chemical Engineering ; Carbon dioxide utilization in catalysis
Authors: Matthew J. McDermott | Shyam Dwaraknath | Kristin A. Persson
Source: Research Square (preprint, 2020-06-30)
Field: Materials Science — Materials Chemistry

A graph-based network for predicting chemical reaction pathways in solid-state materials synthesis Abstract Accelerated synthesis of inorganic materials remains a significant challenge in the search for novel, functional materials. Many of the chemical principles which enable "synthesis by design" in synthetic organic chemistry do not exist in solid-state chemistry, despite extensive computed/experimental thermochemistry data. We present a chemical reaction network model constructed from thermochemistry databases that captures features of the thermodynamic phase space which synthesis reactions traverse. Directed edges in the network are assigned weights via a transformation that maps reaction parameters to costs. We devise a computationally tractable approach for suggesting likely reaction pathways via application of pathfinding algorithms and linear combination of lowest-cost paths in the network. We demonstrate initial success of the reaction network in predicting a complex metathesis reaction pathway toward yttrium manganese oxide YMnO 3 . The reaction network presents new opportunities for enabling reaction pathway prediction, rapid iteration between experimental/theoretical results, and ultimately, control of synthesis of solid-state materials. Thermochemistry ; Computer science ; Chemical reaction ; Salt metathesis reaction ; Graph ; Chemistry ; Algorithm ; Theoretical computer science ; Metathesis ; Polymerization ; Organic chemistry ; Physical chemistry Machine Learning in Materials Science ; Catalysis and Oxidation Reactions ; Computational Drug Discovery Methods
Authors: I Gusti Agung Putra Adnyana
Source: International Journal of Physical Sciences and Engineering (article, 2020-01-01)
Field: Materials Science — Materials Chemistry

Rare earth ion contribution in barium hexaferrite structure to a change of magnetocrystalline anisotropy to improving its magnetic properties Rare earth ion contribution in barium hexaferrite structure to a change of magneto-crystalline anisotropy to improving its magnetic properties has been investigated. A series of simples of Ba1-xCexFe12O19 with the variation of x (x = 0.0-0.5) were prepared by solid-state reactions using mechanical deformation techniques. The oxide materials used for sample preparation are BaCO3, Fe2O3, and CeO2 with the ratio of material used is adjusted to the stoichiometric calculation for variations of Ce4+ substitution. The phase identification results show that the reaction took place perfectly and successfully formed a single-phase Ba1-xCexFe12O19 namely at the composition x = 0 and x = 0.1. while for the composition x&gt; 0.1, it is formed in three phases. Particle morphology in the composition x = 0 and x = 0.1 has very good and uniform particle homogeneity across the surface of the sample in the form of polygonal particles. So the substitution of Ce atoms into the barium hexaferrite structure is only able at the composition limit x = 0.1. In the composition x = 0.1 has been able to increase the coercivity and magnetization fields. It can be concluded that the permanent magnet with the composition Ba0,9Ce0.1F12O19 gives the best results. Magnetocrystalline anisotropy ; Coercivity ; Materials science ; Barium ; Anisotropy ; Magnetic anisotropy ; Magnetization ; Stoichiometry ; Magnet ; Remanence ; Analytical Chemistry (journal) ; Crystallography ; Nuclear magnetic resonance ; Condensed matter physics ; Metallurgy ; Chemistry ; Magnetic field ; Physical chemistry ; Physics Magnetic Properties and Synthesis of Ferrites ; Magnetic Properties and Applications
Authors: Mohamed Amine Zoui | Saïd Bentouba | Mahmoud Bourouis
Source: Algerian Journal of Renewable Energy and Sustainable Development (article, 2020-06-15)
Field: Materials Science — Materials Chemistry

The Potential of Solar Thermoelectric Generator STEG for Implantation in the Adrar Region Asolar thermoelectric generator STEG is a system similar to photovoltaics in the specificity of converting solar energy directly into electrical energy without the need for a mechanical transaction. However, compared to photovoltaics, its introduction into large-scale solar power generation has never been achieved, largely due to the low efficiency of the main component of STEG, the thermoelectric TE module. In contrast to other sectors where TE technology is emerging and growing a rapid development that consequently leads to the discovery of new materials, more TE efficient and adapted design engineering. From this reality, STEG has the potential to become a competing alternative technology to the dominant solar photovoltaic systems, especially in hot regions where the PV system suffers from the progressive and precocious degradation of its original properties, leading to a decrease in lifetime and efficiency due to thermal fatigue caused by the excessive heating of the cells by solar infrared radiation that is useless for PV conversion. The concrete example of our study is in Adrar region (south-west Algeria) which is among the hottest and sunniest areas in the world. A selective analysis of the most suitable STEG system for the Adrar region is proposed, based on state-of-the-art data of STEG systems realized and simulated in the scientific literature Photovoltaics ; Photovoltaic system ; Thermoelectric generator ; Electricity generation ; Solar energy ; Environmental science ; Engineering physics ; Materials science ; Thermoelectric effect ; Electrical engineering ; Power (physics) ; Engineering ; Physics Advanced Thermoelectric Materials and Devices ; Solar Thermal and Photovoltaic Systems ; Thermal Radiation and Cooling Technologies