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81.
Aleksandr A. Chernyshov Kirill V. Karelsky Arakel S. Petrosyan 《Flow, Turbulence and Combustion》2008,80(1):21-35
Large eddy simulation method is formulated for study of compressible magnetohydrodynamic turbulence and assessment of different
subgrid-scale models as applied for decaying case is performed. The filtered equations of compressible magnetopause using
the mass-weighted filtering operation are obtained. Mass-weighted filtered equations for large-scale turbulent component comprise
subgrid-scale terms and five models for closure of the subgrid-scale terms are suggested. In present paper the obtained results
of numerical computations for large eddy simulation are compared with the results of direct numerical simulation of three-dimensional
compressible magnetohydrodynamic turbulence. Assessment of five subgrid-scale models of large eddy simulation for MHD flows
is fulfilled. The comparisons between large eddy simulation and direct numerical simulation are carried out regarding the
temporal evolution of the global quantities kinetic and magnetic energy, cross helicity and the spectra of kinetic and magnetic
energy. 相似文献
82.
Evgenij V. Zarudnitskii Aleksandr A. Yurchenko Anatolij S. Merkulov Marina G. Semenova Aleksandr M. Pinchuk Andrej A. Tolmachev 《Heteroatom Chemistry》2005,16(7):648-655
The reaction of phosphorus(III) halides with 6‐substituted imidazo[2,1‐b]thiazoles in the presence of bases proceeds regioselectively and affords 5‐phosphinoimidazo[2,1‐b]thiazoles, useful synthons for the preparation of various P(III) and P(V) derivatives. 5‐Phosphinoimidazo[2,1‐b]thiazoles are selectively alkylated at the phosphorus or heterocyclic nitrogen atom, depending on the alkylating agent. © 2005 Wiley Periodicals, Inc. Heteroatom Chem 16:648–655, 2005; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/hc.20166 相似文献
83.
Sergei D. Kirik Ekaterina G. Yakovleva Aleksandr F. Shimanskii Yurii G. Kovalev 《Acta Crystallographica. Section C, Structural Chemistry》2001,57(12):1367-1368
The title compound, cadmium bismuth dioxide chloride, CdBiO2Cl, was obtained as a white powder by reaction of solid BiOCl with CdO at 973 K. Ab initio crystal structure determination was carried out using X-ray powder diffraction techniques, including direct methods for atom location and Rietveld fitting for the final refinement. Being monoclinic, the crystal structure can be related to tetragonal Sillen layered phases. The main structural elements present are CdBiO2+ pleated metal–oxygen layers alternating with Cl layers along the c axis, whereas along the b axis, all atoms are on mirror planes. The formation of a strong Cd—Cl bond draws the layers together, causing layer deformation and a monoclinic distortion in the layer arrangement. 相似文献
84.
Yuriy G. Denisenko Victor V. Atuchin Maxim S. Molokeev Alexander E. Sedykh Nikolay A. Khritokhin Aleksandr S. Aleksandrovsky Aleksandr S. Oreshonkov Nikolai P. Shestakov Sergey V. Adichtchev Alexey M. Pugachev Elena I. Salnikova Oleg V. Andreev Illaria A. Razumkova Klaus Müller-Buschbaum 《Molecules (Basel, Switzerland)》2022,27(13)
Praseodymium sulfate was obtained by the precipitation method and the crystal structure was determined by Rietveld analysis. Pr2(SO4)3 is crystallized in the monoclinic structure, space group C2/c, with cell parameters a = 21.6052 (4), b = 6.7237 (1) and c = 6.9777 (1) Å, β = 107.9148 (7)°, Z = 4, V = 964.48 (3) Å3 (T = 150 °C). The thermal expansion of Pr2(SO4)3 is strongly anisotropic. As was obtained by XRD measurements, all cell parameters are increased on heating. However, due to a strong increase of the monoclinic angle β, there is a direction of negative thermal expansion. In the argon atmosphere, Pr2(SO4)3 is stable in the temperature range of T = 30–870 °C. The kinetics of the thermal decomposition process of praseodymium sulfate octahydrate Pr2(SO4)3·8H2O was studied as well. The vibrational properties of Pr2(SO4)3 were examined by Raman and Fourier-transform infrared absorption spectroscopy methods. The band gap structure of Pr2(SO4)3 was evaluated by ab initio calculations, and it was found that the valence band top is dominated by the p electrons of oxygen ions, while the conduction band bottom is formed by the d electrons of Pr3+ ions. The exact position of ZPL is determined via PL and PLE spectra at 77 K to be at 481 nm, and that enabled a correct assignment of luminescent bands. The maximum luminescent band in Pr2(SO4)3 belongs to the 3P0 → 3F2 transition at 640 nm. 相似文献
85.
Chen Zhou Matthew R. Hermes Dihua Wu Jie J. Bao Riddhish Pandharkar Daniel S. King Dayou Zhang Thais R. Scott Aleksandr O. Lykhin Laura Gagliardi Donald G. Truhlar 《Chemical science》2022,13(26):7685
Strong electron correlation plays an important role in transition-metal and heavy-metal chemistry, magnetic molecules, bond breaking, biradicals, excited states, and many functional materials, but it provides a significant challenge for modern electronic structure theory. The treatment of strongly correlated systems usually requires a multireference method to adequately describe spin densities and near-degeneracy correlation. However, quantitative computation of dynamic correlation with multireference wave functions is often difficult or impractical. Multiconfiguration pair-density functional theory (MC-PDFT) provides a way to blend multiconfiguration wave function theory and density functional theory to quantitatively treat both near-degeneracy correlation and dynamic correlation in strongly correlated systems; it is more affordable than multireference perturbation theory, multireference configuration interaction, or multireference coupled cluster theory and more accurate for many properties than Kohn–Sham density functional theory. This perspective article provides a brief introduction to strongly correlated systems and previously reviewed progress on MC-PDFT followed by a discussion of several recent developments and applications of MC-PDFT and related methods, including localized-active-space MC-PDFT, generalized active-space MC-PDFT, density-matrix-renormalization-group MC-PDFT, hybrid MC-PDFT, multistate MC-PDFT, spin–orbit coupling, analytic gradients, and dipole moments. We also review the more recently introduced multiconfiguration nonclassical-energy functional theory (MC-NEFT), which is like MC-PDFT but allows for other ingredients in the nonclassical-energy functional. We discuss two new kinds of MC-NEFT methods, namely multiconfiguration density coherence functional theory and machine-learned functionals.This feature article overviews recent work on active spaces, matrix product reference states, treatment of quasidegeneracy, hybrid theory, density-coherence functionals, machine-learned functionals, spin–orbit coupling, gradients, and dipole moments. 相似文献
86.
We show that neural networks with an absolute value activation function and with network path norm, network sizes and network weights having logarithmic dependence on can -approximate functions that are analytic on certain regions of . 相似文献
87.
Dr. Oliver R. Maguire Dr. Albert S. Y. Wong Mathieu G. Baltussen Peer van Duppen Aleksandr A. Pogodaev Prof. Dr. Wilhelm T. S. Huck 《Chemistry (Weinheim an der Bergstrasse, Germany)》2020,26(7):1676-1682
Current efforts to design functional molecular systems have overlooked the importance of coupling out-of-equilibrium behaviour with changes in the environment. Here, the authors use an oscillating reaction network and demonstrate that the application of environmental forcing, in the form of periodic changes in temperature and in the inflow of the concentration of one of the network components, removes the dependency of the periodicity of this network on temperature or flow rates and enforces a stable periodicity across a wide range of conditions. Coupling a system to a dynamic environment can thus be used as a simple tool to regulate the output of a network. In addition, the authors show that coupling can also induce an increase in behavioural complexity to include quasi-periodic oscillations. 相似文献
88.
Sulfonated octa‐substituted Co(II) phthalocyanines immobilized on silica matrix as catalyst for Thiuram E synthesis
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Artur Vashurin Yury Marfin Ilya Tarasyuk Ilya Kuzmin Serafima Znoyko Aleksandr Goncharenko Evgeny Rumyantsev 《应用有机金属化学》2018,32(9)
Silica nanoparticles were obtained during the work according to two different sol–gel methods. In first one Schtrober's technique and series of cobalt phthalocyanine metal complexes varying in peripheral substituents were used. Second method was performed using the same complexes but differed in applying surface‐active substance (SAS) and two precursors – tetraethoxysilane (TEOS) and aminopropyltrimethoxysilane (APTMOS). All obtained hybrid materials were analyzed via SEM, the size of single particle was studied, which in all cases was about 200 nm. In order to investigate hybrid's characteristics laser diffraction and liquid nitrogen adsorption methods were applied. Distinction in pore's specific volume of differently‐obtained nanoparticles was found. Catalytic activity of all obtained materials were tested in conversion of N,N‐diethylcarbamodithiolate to thiuram E. Effect of peripherally substituted phthalocyanines and morphology of matrixes were manifested on catalytic activity of the hybrids. 相似文献
89.
90.
Aleksandr L Simonian Alexander Revzin James R WildJerry Elkind Michael V Pishko 《Analytica chimica acta》2002,466(2):201-212
The electrostatic assembly of nanocomposite thin films consisting of alternating layers of an organometallic redox polymer (RP) and oxidoreductase enzymes, glucose oxidase (GOX), lactate oxidase (LOX) and pyruvate oxidase (PYX), was investigated. Multilayer nanostructures were fabricated on gold surfaces by the deposition of an anionic self-assembled monolayer of 11-mercaptoundecanoic acid, followed by the electrostatic attachment of a cationic RP, poly(vinylpyridine Os(bis-bipyridine)2Cl-co-allylamine) (PVP-Os-AA), and anionic oxidoreductase enzymes. Surface plasmon resonance (SPR) spectroscopy, Fourier transform infrared external reflection spectroscopy (FT-IR-ERS) and electrochemistry were employed to characterize the assembly of these nanocomposite films. The surface concentration of GOX was found to be 2.4 ng/mm2 for the first enzyme layer and 1.96 ng/mm2 for the second enzyme layer, while values of 10.7 and 1.3 ng/mm2 were obtained for PYX and LOX, respectively. The apparent affinity constant for GOX adsorption was found to be 8×107 M−1. FT-IR-ERS was used to verify the incorporation of GOX and its conformational stability inside of these nanocomposite thin films. An SPR instrument with a flow-through cell was modified by additions of Ag/AgCl reference and Pt counter electrodes, with the gold-coated SPR surface film serving as the working electrode. This enabled real-time observation of the assembly of sensing components and immediate, in situ electrochemical verification of substrate-dependent current upon the addition of enzyme to the multilayer structure. A glucose-dependant amperometric response with sensitivity of 0.197 μA/cm2/mM for a linear range of 1-10 mM of glucose was obtained. The SPR and FT-IR-ERS studies also showed no desorption of polymer or enzyme from the nanocomposite RP-GOX structure when stored in aqueous environment occurred over the period of 3 weeks, suggesting that decreasing substrate sensitivity with time was due to loss of enzymatic activity rather than loss of film compounds from the nanostructure. 相似文献