On compact quantum semigroup QS red

We study some properties of a reduced semigroup C*-algebra of a semigroup S. For the semigroup C*-algebra generated by the deformation of the algebra of continuous functions on a compact abelian group we obtain a structure of a compact quantum semigroup. We also consider morphisms of constructed compact quantum semigroups.     

Optical transmission spectra of a silicate glass containing nanocrystallites of cadmium sulphoselenide

The optical transmission spectra of CdSe _x S_1-x doped low viscosity silicate glass are experimentally studied. Glass samples were subjected to one- or multi-step heat treatment for different lengths of time. We have followed the modification of the absorption spectra after each heat treatment. The red shift of the absorption edge and the accompanying change of coloration from orange to red are explained by size-quantization effects in the energy spectrum of electrons and holes in semiconductor nanoparticles thermally developed in low viscosity glass matrix. X-ray diffraction data show no stoichiometry changes during the heat treatment processes. Crystallites composition ( ) defined from the diffraction peaks was very close to the value estimated from the position of absorption edge.Received: 14 March 2003, Published online: 9 September 2003PACS: 79.60.Jv Interfaces; heterostructures; nanostructures - 78.20.Ci Optical constants (including refractive index, complex dielectric constant, absorption, reflection and transmission coefficients, emissivity) - 78.40.Fy Semiconductors     

The near infrared (0.8−2.6µm) absorption spectrum of a dense sodium vapor and possible mechanisms of the spectrum formation

The absorption coefficient of a dense sodium vapor (N₀ ～ 10¹⁷–10¹⁸ cm^{? 3}) in the near infrared spectral range (0.8–2.6 µm) was measured in a homogeneously heated isolated cell. In the range of parameters studied, the sample exhibits significant absorption. Neither the observed spectral features nor the measured absorption coefficients can be explained using the existing notions of the possible absorption mechanisms (absorption due to a forbidden intercombination transition, collision-induced processes, the trimer vapor component, and many-particle effects) and the available data.     

Hydrocarbalkoxylation of cyclohexene and carbalkoxylation of cyclohexanol with formic esters

Conclusions Mixtures of the esters of the 1-methylcyclopentanecarboxylic and cyclohexanecarboxylic acids were obtained in a 48 ratio by the hydrocarbalkoxylation of cyclohexene and the carbalkoxylation of cyclohexanol with alkyl formates at atmospheric pressures and temperatures of 10–30° in the presence of acids.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 3, pp. 704–705, March, 1973.     

Estimate of the Remainder of the Best Quadratic Approximation of Differentiable Functions by Polynomials

We establish lower and upper bounds for the quantity

Synchrotron radiation from a longitudinally polarized relativistic spinning particle in pseudoclassical theory

The spin dependence of the intensity and polarization of synchrotron radiation from a longitudinally polarized particle moving at a constant speed along a circle in a uniform magnetic field is investigated within the pseudoclassical approach.