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31.
E. Kh. Mukhamedzhanov M. M. Borisov A. N. Morkovin A. A. Antonenko A. P. Oreshko E. N. Ovchinnikova V. E. Dmitrienko 《JETP Letters》2008,86(12):783-787
The 222 and 600 reflections near the germanium absorption K edge were studied on the Kurchatov synchrotron radiation source. The energy spectrum of the 222 reflection is caused by the
interference of the weak nonresonant and purely resonant contributions to the tensor atomic factor, whereas the 600 reflection
is purely resonant. The energy dependence of the magnitude and phase of the resonant contribution to the scattering amplitude
was determined from a change in the interference pattern. The numerical simulation of the energy spectra of reflections with
the inclusion of the dipole-quadrupole and thermally induced contributions shows that the latter is dominant at room temperature. 相似文献
32.
Banzaraktsaeva S. P. Surmina M. A. Chumachenko V. A. Ovchinnikova E. V. 《Russian Journal of Applied Chemistry》2020,93(5):721-728
Russian Journal of Applied Chemistry - Isopropanol is one of the main organic impurities present in bioethanol. Effect of the isopropanol impurity in the feed on catalytic dehydration of 92%... 相似文献
33.
Established and emerging atmospheric pressure surface sampling/ionization techniques for mass spectrometry 总被引:1,自引:0,他引:1
The number and type of atmospheric pressure techniques suitable for sampling analytes from surfaces, forming ions from these analytes, and subsequently transporting these ions into vacuum for interrogation by MS have rapidly expanded over the last several years. Moreover, the literature in this area is complicated by an explosion in acronyms for these techniques, many of which provide no information relating to the chemical or physical processes involved. In this tutorial article, we sort this vast array of techniques into relatively few categories on the basis of the approaches used for surface sampling and ionization. For each technique, we explain, as best known, many of the underlying principles of operation, describe representative applications, and in some cases, discuss needed research or advancements and attempt to forecast their future analytical utility. Copyright (c) 2008 John Wiley & Sons, Ltd. 相似文献
34.
35.
Resonant diffraction of synchrotron radiation (SR) is a modern method of studying the structure and properties of condensed matter that can be implemented on third-generation synchrotrons. This method allows one to investigate local properties of media (including magnetic and electronic ones) and observe thermal vibrations, defects, and orbital and charge orderings. A brief review of the advance provided by SR resonant diffraction is presented, and the capabilities of this method for analyzing phase transitions are considered in more detail by the example of potassium dihydrogen phosphate and rubidium dihydrogen phosphate crystals. It is shown that the investigation of the temperature dependence of forbidden reflections not only makes it possible to observe the transition from para- to ferroelectric phase, but also gives information about the proton distribution at hydrogen bonds. 相似文献
36.
O. A. Kilikovskaya N. V. Ovchinnikova 《Journal of Applied Mechanics and Technical Physics》2012,53(5):777-783
A model problem of plane strain of an elastoplastic material is considered. It is shown that the type of stress state in the loading plane affects the dependence of the solution on Poisson??s ratio. It is found that for the state in which the principal stresses in the loading plane are approximately equal, the effect of compressibility is significant, so that it must be taken into account. It is shown that if the principal stresses in the loading plane have different signs, the solutions for compressible and incompressible materials are almost the same. 相似文献
37.
Yu. A. Titova O. V. Fedorova I. G. Ovchinnikova G. L. Rusinov V. N. Charushin 《Russian Journal of Applied Chemistry》2012,85(4):656-660
The effect of nanosized metal oxides (Al, Mg, Cu, Ni oxides) on the synthesis of chalcones that are key intermediate in the synthesis of Nitrendipine and Felodipine drugs was examined. 相似文献
38.
A. A. Ovchinnikov M. Ya. Ovchinnikova 《Journal of Experimental and Theoretical Physics》2001,93(1):153-160
Variational tests are performed for current order parameters as probable sources of the pseudogap normal state of cuprates. The calculations are carried out based on the states with correlations of the valence bond type whose formation can induce in principle both the superconducting order of the d symmetry and current phases. It is shown for the t-t′-U Hubbard models with a large value of U(~8t) and the Hubbard splitting of the conduction band that (1) phases of alternating charge and longitudinal spin currents cannot be realized and (2) transverse spin currents are not compatible with the superconducting order and they could exist against the normal-state background only within a very narrow doping region near the optimal one. This region does not correspond to the region of existence of a pseudogap in cuprates, which refutes the above-mentioned hypothesis of the pseudogap origin. The requirements to the parameters of models for which the consideration of correlations of the valence bond type yields a reasonable phase curve. The existence of current phases in the t-t′-U-V Hubbard models with a strong interaction (V>0.25t) of particles in neighboring sites is predicted when the d-superconductivity is completely suppressed. 相似文献
39.
A. A. Ovchinnikov M. Ya. Ovchinnikova E. A. Plekhanov 《Journal of Experimental and Theoretical Physics》1999,88(2):356-369
The phase diagram, nature of the normal state pseudogap, type of the Fermi surface, and behavior of the superconducting gap
in various cuprates are discussed in terms of a correlated state with valence bonds. The variational correlated state, which
is a band analogue of the Anderson (RVB) states, is constructed using local unitary transformations. Formation of valence
bonds causes attraction between holes in the d-channel and corresponding superconductivity compatible with antiferromagnetic spin order. Our calculations indicate that
there is a fairly wide range of doping with antiferromagnetic order in isolated CuO2 planes. The shape of the Fermi surface and phase transition curve are sensitive to the value and sign of the hopping interaction
t′ between diagonal neighboring sites. In underdoped samples, the dielectrization of various sections of the Fermi boundary,
depending on the sign of t′, gives rise to a pseudogap detected in photoemission spectra for various quasimomentum directions. In particular, in bismuth-and
yttrium-based ceramics (t′>0), the transition from the normal state of overdoped samples to the pseudogap state of underdoped samples corresponds to
the onset of dielectrization on the Brillouin zone boundary near k=(0,π) and transition from “large” to “small” Fermi surfaces. The hypothesis about s-wave superconductivity of La-and Nd-based ceramics has been revised: a situation is predicted when, notwithstanding the d-wave symmetry of the superconducting order parameter, the excitation energy on the Fermi surface does not vanish at all points
of the phase space owing to the dielectrization of the Fermi boundary at k
x=±
k
y. The model with orthorhombic distortions and two peaks on the curve of T
c versus doping is discussed in connection with experimental data for the yttrium-based ceramic.
Zh. éksp. Teor. Fiz. 115, 649–674 (February 1999) 相似文献
40.
Tatjana Ovchinnikova Irina Zhuravleva Ljudmila Bush Nicolay Il'in 《Macromolecular Symposia》1999,144(1):303-311
The study of glycolide (GL) and ethylenoxalate (EO) copolymerization with the use of SnCl2 2 H2O as a catalyst was carried out by 1H NMR spectroscopy. Monomer reactivities are found to be close and equal to 1,1 and 1,11 for GL and 0,71 and 0,85 for EO at 150 and 170 °C, respectively. Kinetic data obtained show that the reaction proceeds without induction period up to entire consumption of every monomer. The detailed identification of 1H spectra enables to follow the polymer microstructure in the course of copolymerization. Thermal properties of copolymers and their biodegradation abilities have been studied. The biodegradation rate is shown to increase with growing EO proportion in the copolymer. The lactone biodegradation mechanism where the electrophility of carbon and nucleophility of OH group are playing the most important role, is suggested. The correlation between the biodegradation rate and the chemical shift in 13C NMR spectra of the carbon atom of the carbonyl group has been established. 相似文献