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1.
Sizova N. L. Golovina T. G. Konstantinova A. F. Dudka A. P. 《Crystallography Reports》2021,66(6):1045-1050
Crystallography Reports - The anisotropy of microhardness and fracture of the (0001) basal plane of langasite crystal has been studied using Berkovich indentation under a load of 100 g at different... 相似文献
2.
Kutkin A. V. Kondrat’ev V. A. Golovina N. V. Zhidkov M. E. Chubarova O. V. Litvinov Yu. M. 《Russian Journal of Organic Chemistry》2021,57(7):1173-1175
Russian Journal of Organic Chemistry - A procedure has been developed for the direct synthesis of N,N-dimethyloxazolidinium salts by chloromethylation of 2-(dimethylamino)ethanol in the presence of... 相似文献
3.
Crystallography Reports - Raman scattering spectra have been investigated in La3Ga5SiO14 langasite crystals with Cr and Fe impurities and La3Ga5.25Ta0.25Si0.5O14 crystalline solid solution. It is... 相似文献
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We study random Hamiltonians on finite-size cubes and waveguide segments of increasing diameter. The number of random parameters determining the operator is proportional to the volume of the cube. In the asymptotic regime where the cube size, and consequently the number of parameters as well, tends to infinity, we derive deterministic and probabilistic variational bounds on the lowest eigenvalue, i.e., the spectral minimum, as well as exponential off-diagonal decay of the Green function at energies above, but close to the overall spectral bottom. 相似文献
7.
A. V. Shastin V. L. Korolev T. S. Pivina T. I. Godovikova B. L. Korsunskii P. A. Belyakov N. I. Golovina G. V. Shilov 《Russian Chemical Bulletin》2009,58(11):2207-2216
The molecular geometries and electronic structures of 2,4,6-tris(nitromethyl)-1,3,5-triazine isomers were investigated by
the density functional method DFT/B3LYP/6-311++G** to elucidate the structural factors responsible for the stability of these
systems. It was shown that a characteristic feature of the nitromethyl tautomer (1) of 2,4,6-tris (nitromethyl)-1,3,5-triazine consists in nonvalence interactions between an oxygen atom of nitro group and
a carbon atom of triazine ring, which are probably due to Coulomb attraction between them. The tautomer with the 2,4,6-tris
(nitromethylene)-hexahyrdo-1,3,5-triazine structure (2) is stabilized trough direct polar conjugation between the amino and nitro groups at the double bond. Structural strain of
the molecule with the 2,4,6-tris(aci-nitromethyl)-1,3,5-triazine structure (3) is the reason for its thermodynamic instability. X-ray data indicate that the compound under study exists in the triazine
tautomeric form 1 and the distances between oxygen atoms of nitro group and carbon atom of the triazine ring are shortened. NMR data suggest
the existence of triazine in the nitromethyl form 1 in acetonitrile and acetone and a tautomeric equilibrium between the nitromethyl and nitromethylene forms in a more polar
solvent (DMSO). The results obtained suggest a Coulomb-type stabilization of the 2,4,6-tris(nitromethyl)-1,3,5-triazine molecule
in the gas phase, in the crystal, and in nonpolar solvents. 相似文献
8.
The article considers the determination of the boundary of a two-dimensional region in which an initial boundary-value problem
for the heat equation is defined, given the solution of the problem for all time instants at some points of the region. The
direct problem is reduced to an integral equation, and numerical solutions of the inverse problem are obtained for the case
when the boundary is an ellipse. We investigate the sensitivity of the observed variables to the location (relative to the
boundary) of the point where the right-hand side of the equation is specified.
Translated from Prikladnaya Matematika i Informatika, No. 30, 2008, pp. 18–24. 相似文献
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I. S. Golovina B. D. Shanina I. N. Geifman A. A. Andriiko L. V. Chernenko 《Physics of the Solid State》2012,54(3):551-558
The electron paramagnetic resonance spectra of KTaO3: Mn nanocrystalline powders in the temperature range from 77 to 620 K have been measured and studied for the first time.
The change observed in the spectra has been investigated as a function of the doping level. The doping regions in which Mn2+ ions are individual paramagnetic impurities have been established, as well as the regions where the dipole-dipole and exchange
interactions of these ions begin to occur. The spin-Hamiltonian constants for the spectrum of non-interacting individual Mn2+ ions have been determined as follows: g = 2.0022, D = 0.0170 cm−1, and A = 85 × 10−4 cm−1. A significant decrease in the axial constant D in the KTaO3: Mn nanopowder, as compared to the single crystal, has been explained by the remoteness of the charge compensator from the
paramagnetic ion and by the influence of the surface of the nanoparticle. It has been assumed that the Mn2+ ions are located near the surface and do not penetrate deep into the crystallites. 相似文献