Laser-Synchrotron Facility of the National Research Centre “Kurchatov Institute”

Crystallography Reports - The laser-synchrotron facility (LSF) of the National Research Centre “Kurchatov Institute” (NRC KI) is a unique research complex that combines unprecedented...     

Application of frequency converters to femtosecond laser radiation for lidar monitoring of the atmosphere

Possibilities of using superbroadband nonlinear-optical frequency converters for femtosecond laser pulses in lidar sensing of the atmosphere are analyzed. New biaxial nonlinear crystals in which the conditions of phase and group matching can be satisfied simultaneously are basic elements of frequency converters. A technique for the broadband lidar sensing of the gas composition of the atmosphere based on the differential optical atmospheric spectroscopy and the differential absorption methods is described. The lidar sensing of gas constituents of the atmosphere using frequency converted femtosecond laser radiation is simulated numerically.     

Structured mesoporous Mn, Fe, and Co oxides: Synthesis, physicochemical, and catalytic properties

Structured mesoporous Mn, Fe, and Co oxides are synthesized using “soft” and “hard” templates; the resulting materials are characterized by XRD, SEM, TEM, BET, and TG. It is shown that in the first case, the oxides have high surface areas of up to 450 m²/g that are preserved after calcination of the material up to 300°C. Even though, the surface area of the oxides prepared by the “hard-template” method does not exceed 100 m²/g; it is, however, thermally stable up to 500°C. Catalytic activity of mesoporous oxides in methanol conversion was found to depend on both the nature of the transition metal and the type of template used in synthesis.     

Equational Noetherianness of rigid soluble groups

A group G is said to be rigid if it contains a normal series of the form G = G ₁ > G ₂ > … > G _m  > G _m + 1 = 1, whose quotients G _i /G _i + 1 are Abelian and are torsion free as right Z[G/G _i ]-modules. In studying properties of such groups, it was shown, in particular, that the above series is defined by the group uniquely. It is known that finitely generated rigid groups are equationally Noetherian: i.e., for any n, every system of equations in x ₁, …, x _n over a given group is equivalent to some of its finite subsystems. This fact is equivalent to the Zariski topology being Noetherian on G ⁿ , which allowed the dimension theory in algebraic geometry over finitely generated rigid groups to have been constructed. It is proved that every rigid group is equationally Noetherian. Supported by RFBR (project No. 09-01-00099) and by the Russian Ministry of Education through the Analytical Departmental Target Program (ADTP) “Development of Scientific Potential of the Higher School of Learning” (project No. 2.1.1.419). Translated from Algebra i Logika, Vol. 48, No. 2, pp. 258–279, March–April, 2009.     

On the destruction of the superconducting state of a multiconductor composite

The kinetics of thermal instability in the form of an initially arising local region of normal conductivity is investigated using a model of a discrete superconducting medium in which the components are assumed to interact thermally across a thermally thin intermediate layer. It is found that certain characteristic features of the transient processes occurring at currents close to the minimum current for propagation of the normal zone must be taken into account in an experimental determination of the normal-zone propagation velocities in multiconductor composites. Zh. Tekh. Fiz. 69, 133–136 (February 1999)