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81.
82.
Conventional lattice Boltzmann models for the simulation of fluid dynamics are restricted by an error in the stress tensor that is negligible only for small flow velocity and at a singular value of the temperature. To that end, we propose a unified formulation that restores Galilean invariance and the isotropy of the stress tensor by introducing an extended equilibrium. This modification extends lattice Boltzmann models to simulations with higher values of the flow velocity and can be used at temperatures that are higher than the lattice reference temperature, which enhances computational efficiency by decreasing the number of required time steps. Furthermore, the extended model also remains valid for stretched lattices, which are useful when flow gradients are predominant in one direction. The model is validated by simulations of two- and three-dimensional benchmark problems, including the double shear layer flow, the decay of homogeneous isotropic turbulence, the laminar boundary layer over a flat plate and the turbulent channel flow. 相似文献
83.
Evdokimov S. V. Izucheev V. I. Kondratyuk E. S. Polishchuk B. V. Sadovsky S. A. Shangaraev A. A. Kharlov Yu. V. 《Physics of Atomic Nuclei》2021,84(9):1647-1652
Physics of Atomic Nuclei - According to modern theories, the parameters of neutral mesons such as their mass and width are closely connected with the medium in which the mesons are present.... 相似文献
84.
Are there reliable DFT approaches for 13C NMR chemical shift predictions of fullerene C60 derivatives? 下载免费PDF全文
Arthur R. Tulyabaev Ilya I. Kiryanov Ilnaz S. Samigullin Leonard M. Khalilov 《International journal of quantum chemistry》2017,117(1):7-14
The relationships between experimental and theoretical 13C NMR chemical shifts of a pristine fullerene C60, monoadducts from [2 + n] cycloaddition (n = 1–3), and one [2 + 1] bis‐adduct are systematically analyzed for the first time by using diverse quantum‐chemical levels of theory. These levels involved B3LYP, B3PW91, B97‐2, mPW1PW91, PBE1PBE, and X3LYP hybrid functionals combined with 3‐21G, 6‐31G, 6‐31G(d), 6‐31G(d,p), 6‐31G(d,2p), LanL2DZ, and SDDAll basis sets. X3LYP/6‐31G approach is determined to have the lowest deviations from the 13C NMR experimental data compared to the other methods for all the fullerene compounds (mean absolute error value is 0.856 ppm and root mean squared error value is 1.197 ppm). The highest deviations are characteristic for α (sp2 C2/C5/C8/C10) and β (sp2 C6/C7/C11/C12) carbon atoms relative to a functionalization site and for those (sp3 C1/C9) directly attached with a side fragment in the [2 + n] monoadducts (n = 1–3). A probable reason of such deviation is that the approaches do not take into account a contribution of paramagnetic ring currents to 13C NMR chemical shifts. The results will be useful in design of novel fullerene derivatives and in performing unambiguous 13C NMR chemical shift assignments with modern quantum chemistry calculations. 相似文献
85.
86.
Background
Triptolide is a diterpene triepoxide from the Chinese medicinal plant Tripterygium wilfordii Hook F., with known anti-inflammatory, immunosuppressive and anti-cancer properties. 相似文献87.
Irena Pankratov Sara Elhanany Sharona Henig Shunit Zaritsky Ivan Ostapenko Ilya Kuselman 《Accreditation and quality assurance》2010,15(8):459-466
A proficiency testing (PT) scheme was developed for a limited number of analytical laboratories participating in the analysis
of natural water in Israel. Three fit-for-intended-use reference materials (RMs) were prepared for a pilot PT from natural
water: RM-blank and two in-house reference materials (IHRMs) with seven analytes fortified to achieve different levels of
analyte concentrations. The measurands for the PT participants were the traceable spike values certified in the IHRMs, i.e.,
added mass concentrations of the analytes. The RM-blank and IHRMs were found to be homogeneous and stable over 11 days, the
time necessary for the experimental part of the PT. The RMs were distributed to the PT participants as unknown test items
similar to routine samples. The test results were evaluated using their deviations from the IHRM-certified values. Eight Israeli
laboratories took part in the interlaboratory comparison. Individual laboratory performance and metrological compatibility
of the PT results of the participants, as a local group of laboratories, were evaluated for every analyte. 相似文献
88.
Ilya N. Egorov Vladimir L. Rusinov Pavel A. Slepukhin Oleg N. Chupakhin 《Journal of chemical crystallography》2010,40(4):387-390
Abstract
The diastereoselective synthesis, NMR and X-ray structure of (S)-2-((S)-2-(N-Ts-amino)-3-methylbutanoyl)-3-(1H-indol-3-yl)-6-phenyl-3,4-dihydro-1,2,4-triazin-5(2H)-one—a potential antivirus agent are reported. The compound crystallizes in the triclinic space group P1 with unit cell parameters: a = 5.9259(6) ?, b = 9.6370(12) ?, c = 12.9541(9) ?, α = 109.210(9)°, β = 90.804(7)°, γ = 105.074(10)° and Z = 1. 相似文献89.
Hogben HJ Krzystyniak M Charnock GT Hore PJ Kuprov I 《Journal of magnetic resonance (San Diego, Calif. : 1997)》2011,208(2):179-194
We introduce a software library incorporating our recent research into efficient simulation algorithms for large spin systems. Liouville space simulations (including symmetry, relaxation and chemical kinetics) of most liquid-state NMR experiments on 40+ spin systems can now be performed without effort on a desktop workstation. Much progress has also been made with improving the efficiency of ESR, solid state NMR and Spin Chemistry simulations. Spinach is available for download at http://spindynamics.org. 相似文献
90.
de Fouquieres P Schirmer SG Glaser SJ Kuprov I 《Journal of magnetic resonance (San Diego, Calif. : 1997)》2011,212(2):412-417
We report some improvements to the gradient ascent pulse engineering (GRAPE) algorithm for optimal control of spin ensembles and other quantum systems. These include more accurate gradients, convergence acceleration using the Broyden–Fletcher–Goldfarb–Shanno (BFGS) quasi-Newton algorithm as well as faster control derivative calculation algorithms. In all test systems, the wall clock time and the convergence rates show a considerable improvement over the approximate gradient ascent. 相似文献