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81.
A. M. Prokhorov D. N. Kozhevnikov V. L. Rusinov O. N. Chupakhin G. G. Aleksandrov Yu. N. Shvachko D. V. Starichenko A. V. Korolev D. V. Bukhvalov V. V. Ustinov 《Russian Chemical Bulletin》2008,57(3):561-566
The new N,N,O-ligand 6-phenyl-3-(2-pyridyl)-5-(trifluoroacetylmethylidene)-4,5-dihydro-1,2,4-triazine (L) was synthesized, and its complex
with CuII was prepared. The structure of the complex was established by X-ray diffraction. Magnetic measurements and ESR studies were
carried out. Ab initio calculations of the electronic structure, exchange interactions, and the effective magnetic moment were performed. The intrastack
polarization effect between the π states of 1,2,4-triazine and the d states of copper was revealed and numerically validated.
Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 3, pp. 549–554, March, 2008. 相似文献
82.
The data on adsorption of cyclopentane, benzene, and their mixture on active carbon were analyzed by the statistical thermodynamic
model. A method to describe the state of a binary mixture in single micropores was offered. A substantial negative deviation
from Raoult's law predicted by the concept of an ideal adsorption solution is a consequence of a decrease in the excessive
Helmholtz energy brought about by progressive filling when values of the excessive energy are positive over a wide range of
adsorption. The excessive values found for the entropy and internal energy of a mixture of molecules in a single micropore
are negative due to the heterogeneity of the adsorption field. The approach suggested adequately describes the experimental
data and can be used for the determination of differential heats of adsorption.
Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 6, pp. 1070–1076, June, 1999. 相似文献
83.
Alexey V. Ustinov Boris A. Malomed Edward Goldobin 《Physica B: Condensed Matter》2000,280(1-4):239-240
Resonant interaction of a soliton (Josephson fluxon) with its self-generated Josephson plasma waves is studied experimentally, numerically, and analytically. An externally applied magnetic field H forms a cos-like potential relief for the soliton in the annular junction. Soliton motion under the influence of the bias current leads to an emission of plasma waves, which gives rise to a resonance at a certain soliton velocity. This resonance on the current–voltage characteristics shows a clear backbending accompanied by a negative differential resistance. Our analysis quantitatively explains the observed effect. 相似文献
84.
H. Lauter V. Lauter A. Vorobiev M. Mylaev L. Romashev V. Ustinov B. Toperverg 《Physica B: Condensed Matter》2009,404(17):2553-2556
Additional information about the magnetization distribution in magnetic films is obtained with a 3D-polarimetry set-up. A pilot experiment was performed with the neutron polarization aligned perpendicular to the surface of a Fe-film in a magnetic field parallel to its surface. The Larmor-precession in the magnetic field between two current sheets was used to adjust the neutron polarization perpendicular to the sample surface. This new polarization-magnetization configuration was probed with a Fe-film in specular and off-specular scattering. The off-specular scattering is created by the magnetic domain structure of the Fe-film in remanence. The results of specular and off-specular scattering are reproduced by calculations for the configuration of the incoming neutron polarization parallel to the sample surface and the magnetic field and for the configuration of the incoming neutron polarization perpendicular to the sample surface and the magnetic field. 相似文献
85.
M. S. Vasil’eva V. S. Rudnev A. Yu. Ustinov V. G. Kuryavyi O. E. Sklyarenko N. B. Kondrikov 《Russian Journal of Inorganic Chemistry》2009,54(11):1708-1712
We have studied the composition and structure of films 20–30 μm thick prepared by plasmaassisted electrochemical oxidation
(PEO) and additionally modified by impregnation in aqueous solutions of nickel and copper nitrates and then annealed. The
investigative tools used were powder X-ray diffraction, electron probe microanalysis (EPMA), X-ray photoelectron spectroscopy
(XPS), and atomic force microscopy. Unmodified film/titanium composites have a certain catalytic activity in CO oxidation
to CO2 at temperatures above 300°C; for modified layers, these temperatures are noticeably higher. Modification influences the surface
structure, relief, and elemental composition. Relations between the composition and catalytic properties of the oxide layers
are discussed. 相似文献
86.
Ustinov EA Do DD Jaroniec M 《Langmuir : the ACS journal of surfaces and colloids》2006,22(14):6238-6244
Equilibrium adsorption data of nitrogen on a series of nongraphitized carbon blacks and nonporous silica at 77 K were analyzed by means of classical density functional theory to determine the solid-fluid potential. The behavior of this potential profile at large distance is particularly considered. The analysis of nitrogen adsorption isotherms seems to indicate that the adsorption in the first molecular layer is localized and controlled mainly by short-range forces due to the surface roughness, crystalline defects, and functional groups. At distances larger than approximately 1.3-1.5 molecular diameters, the adsorption is nonlocalized and appears as a thickening of the adsorbed film with increasing bulk pressure in a relatively weak adsorption potential field. It has been found that the asymptotic decay of the potential obeys the power law with the exponent being -3 for carbon blacks and -4 for silica surface, which signifies that in the latter case the adsorption potential is mainly exerted by surface oxygen atoms. In all cases, the absolute value of the solid-fluid potential is much smaller than that predicted by the Lennard-Jones pair potential with commonly used solid-fluid molecular parameters. The effect of surface heterogeneity on the heat of adsorption is also discussed. 相似文献
87.
Nitrogen adsorption on a surface of a non-porous reference material is widely used in the characterization. Traditionally, the enhancement of solid-fluid potential in a porous solid is accounted for by incorporating the surface curvature into the solid-fluid potential of the flat reference surface. However, this calculation procedure has not been justified experimentally. In this paper, we derive the solid-fluid potential of mesoporous MCM-41 solid by using solely the adsorption isotherm of that solid. This solid-fluid potential is then compared with that of the non-porous reference surface. In derivation of the solid-fluid potential for both reference surface and mesoporous MCM-41 silica (diameter ranging from 3 to 6.5 nm) we employ the nonlocal density functional theory developed for amorphous solids. It is found that, to our surprise, the solid-fluid potential of a porous solid is practically the same as that for the reference surface, indicating that there is no enhancement due to surface curvature. This requires further investigations to explain this unusual departure from our conventional wisdom of curvature-induced enhancement. Accepting the curvature-independent solid-fluid potential derived from the non-porous reference surface, we analyze the hysteresis features of a series of MCM-41 samples. 相似文献
88.
McWilliam A Lagatsky AA Brown CT Sibbett W Zhukov AE Ustinov VM Vasil'ev AP Rafailov EU 《Optics letters》2006,31(10):1444-1446
A quantum-dot-based saturable absorber has been demonstrated to initiate the generation of femtosecond pulses from a passively mode-locked solid-state laser. Control and tuning of the pulse duration from 58 ps to 158 fs was achieved. The 158 fs transform-limited pulses at 1280 nm are the shortest pulses that were produced from the Cr:forsterite laser passively mode locked by an InAs/InGaAs quantum-dot semiconductor saturable absorber mirror. 相似文献
89.
The spiral waves in the viscous incompressible fluid flow within an arterial vessel modeled by a thin elastic isotropic shell are studied. Asymptotic expansions are constructed for two types of spiral waves. The first type is spiral long wall waves generated (owing to the viscous fluid no-slip at the inner shell wall) by the longitudinal and twist harmonic waves that propagate along the wall. For these waves the amplitude distribution over the vessel cross-section has the form of a boundary layer localized near the inner shell surface. The second is short small-amplitude waves that practically fill the entire vessel cross-section. It is shown that for the short waves the transfer mechanismis the steady-state flow, the role of the longitudinal wall waves and the elastic characteristics of the shell being in this case insignificant. 相似文献
90.
A Kirchhoff-Love type applied theory is used to study the specific characteristics of harmonic waves and vibrations of a helically
anisotropic shell. Special attention is paid to axisymmetric and bending vibrations. In both cases, the dispersion equations
are constructed and a qualitative and numerical analysis of their roots and the corresponding elementary solutions is performed.
It is shown that the skew anisotropy in the axisymmetric case generates a relation between the longitudinal and torsional
vibrations which is mathematically described by the amplitude coefficients of homogeneous waves. In the case of a shell with
rigidly fixed end surfaces, the dependence of the first two natural frequencies on the shell length and the helical line slope
α, i.e., the geometric parameter of helical anisotropy, is studied. A boundary value problem in which longitudinal vibrations
are generated on one of the end surfaces and the other end is free of forces and moments is considered to analyze the degree
of transformation of longitudinal vibrations into longitudinally torsional vibrations. In the case of bending vibrations,
two problems for a half-infinite shell are studied as well. In the first problem, the waves are excited kinematically by generating
harmonic vibrations of the shell end surface in the plane of the axial cross-section, and it is shown that the axis generally
moves in some closed trajectories far from the end surface. In the second problem, the reflection of a homogeneous wave incident
on the shell end is examined. It is shown that the “boundary resonance” phenomenon can arise in some cases. 相似文献