Voronezh State University

About: Voronezh State University is a education organization based out in Voronezh, Russia. It is known for research contribution in the topics: Silicon & Boundary value problem. The organization has 5166 authors who have published 6097 publications receiving 31680 citations. The organization is also known as: VSU & Voronezh University.

Thermal Insulation Properties of Wood Polymeric Sand Composite

Abstract: The mathematical model of a wood polymeric sand composite has been developed, which allows studying the thermal insulation properties of a composite material, taking into account the ratio of wood filler to the other components, the method for obtaining samples, and the type of wood filler. The technique of modeling and analysis of the obtained results is given. By mathematical modeling it was established that the wood polymeric sand composite has thermal insulation properties 2-3 times better than that of construction materials based on concrete. Construction materials based on the developed composite have a higher heat capacity than pure wood, which allows them to better maintain the constancy of the temperature inside the premises with significant daily fluctuations in the external temperature. A series of practical tests were conducted to evaluate the reliability of the results obtained. The discrepancy between theoretical and practical results does not exceed 5%.

Vibrational spectrum and electronic structure of C60-fullerene in an external electric field

Abstract: Evolutions in the restructuring of vibrational spectrum and electronic structure of fullerene C60 in the electric field within the range of values E = 0−0.5 V/A were investigated using the density functional theory. It was found that the electric field shifted and activated vibrational modes H g (1), A g (1), H u (2), H g (4), H g (5), H g (6), H g (7), A g (2), H g (8) in the IR-spectrum and G u (3), G u (6), H u (7) in the Raman-spectrum. The splitting and shift of the h u , t 1u and t 1g orbitals due to the quadratic Stark effect was revealed. The possibility of the optically forbidden h u -t 1u and permitted h u -t 1g energy gaps modulation up to 0.420 and 0.228 eV by a strong electric field was demonstrated.

Two-Photon Bremsstrahlung Processes in Atoms: Polarization Effects and Analytic Results for the Coulomb Potential

Abstract: The partial wave analysis of two-photon free-free (bremsstrahlung) electron transition cross sec- tions during scattering by a static potential U(r), as well as by an atom with a nonzero angular momentum, is carried out. The dipole interaction with radiation is taken into account in the second order of perturbation theory for the general case of elliptic polarization of photons. The polarization and angular dependences of the two- photon potential scattering amplitude is presented as a combination of the scalar product of electron momenta and photon polarization vectors and five atomic parameters containing Legendre polynomials of the scattering angle as well as radial matrix elements depending on the initial ( E) and final (E') electron energies. The results are applicable both for spontaneous double bremsstrahlung at nonrelativistic energies and for induced absorp- tion and emission in the field of a light wave. Specific polarization effects (circular and elliptic dichroism) are analyzed for two-photon bremsstrahlung processes associated with the interference of the Hermite and anti- Hermite parts of the amplitude and depending on the sign of photon helicity. The limiting cases of high and low photon frequencies are investigated analytically, and the asymptotic forms of radial matrix elements and ampli- tudes for the general form of the U(r) potential are determined. Closed analytic expressions are derived for the radial matrix elements of the Coulomb potential in the form of integrals of hypergeometric function, and sin- gularities are singled out in explicit form for E' E. The methods of approximate calculation of the radial matrix elements are discussed, and the results of their exact numerical calculation, as well as angular distribu- tions and the cross sections of induced one- and two-photon emission and absorption, are given for the case of the Coulomb potential. The numerical results show that dichroism effects are quite accessible for experimental observations. © 2002 MAIK "Nauka/Interperiodica".

[Isolation and properties of malate dehydrogenase from meso- and thermophilic bacteria].

Abstract: A scheme of purification of malate dehydrogenase from Macromonas bipunctata strain D-405 and Vulcanithermus medioatlanticus DSM 14978T was developed. This scheme was used to obtain electrophoretically homogeneous enzyme preparations of the mesophilic bacterium M. bipunctata (specific activity, 26.9 ± 0.8 U/mg protein; yield, 10.9%) and the thermophilic bacterium V. medioatlanticus (specific activity, 5.0 ± 0.2 U/mg protein; yield, 19.2%). Using these high-purity enzymatic preparations, the physicochemical and regulatory properties of malate dehydrogenase were studied and the differences in kinetic characteristics and thermal stability of the preparations were determined.