Dialkyldialkoxyphosphonium salts

Conclusions Dialkyldialkoxyphosphonium halides are stable only in the case of branched alkoxy groups. The stability is explained by the difficulty of attack of the isoalkoxy group by halide anions.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 2, pp. 415–417, February, 1971.     

An interior-point method for generalized linear-fractional programming

We develop an interior-point polynomial-time algorithm for a generalized linear-fractional problem. The latter problem can be regarded as a nonpolyhedral extension of the usual linear-fractional programming; typical example (which is of interest for control theory) is the minimization of the generalized eigenvalue of a pair of symmetric matrices linearly depending on the decision variables.     

Unified theory of nuclear reactions based on master equations for finite open systems

It is shown that the use of master equations for finite open systems allows to formulate a unified theory of nuclear reactions, which includes the most frequently used phenomenological models: optical model, DWBA, internuclear cascade and evaporation model.     

Mass distributions of fission fragments emitted by highly excited nuclei

The mass distributions of fission fragments emitted by highly excited nuclei have been investigated for the determination of some peculiarities of fission process. It has been shown that the fragment mass distributions obtained by the time-of-flight method change their character in the region of Ag, as expected in the liquid drop model (LDM). The cascade-evaporation model and the statistical method of Fong describe the experimental data with a good accuracy.     

Influence of polyether ring size and of the nature of substituents on the yields of paramagnetic centers in γ-irradiated mono-and dibenzosubstituted crown ethers at 77 K

Intermediates stabilized in γ-irradiated mono-and dibenzosubstituted crown ethers are studied by ESR spectroscopy at 77 K. PhO radicals and radicals with H-atom abstraction from polyether ring are the main products at low temperature γ-radiolysis. The nature of radicals produced in radiolysis and the yield of radicals,G _R depend on macroring size and on the number of aromatic substiuents. Negative deviation from additive in function ofG _R versus ε of substituents is an evidence of efficient transfer of adsorbed energy to the π-system of aromatic group.     

Polarization spectra of excitonic luminescence of bare ZnCdSe/ZnSe quantum wires

Linearly polarized luminescence spectra of bare (unburied) semiconductor structures with ZnCdSe/ZnSe quantum wires, obtained by reactive ion etching, were investigated. It was found that, regardless of the orientation of the linear polarization of the exciting light, the luminescence radiation of the quantum wires is polarized parallel to the axis of the wires, while the radiation of the buffer layer of the isotropic ZnSe barrier material is oriented perpendicular to the axis of the wires. The polarization features found are due to the modification of the modes of the electromagnetic field near open quantum wires, which occurs as a result of the presence of the vertical interfaces between media with strongly different permittivities. It was also found that, when linearly polarized excitation is used, the alignment of exciton dipole moments strongly influences the polarization properties of the luminescence. Fiz. Tverd. Tela (St. Petersburg) 40, 1559–1562 (August 1998)     

Numerical modeling of the interaction between an electric arc and a gas flow

The interaction between an equilibrium arc discharge and a gas (air or argon) flow at atmospheric pressure and a current of 20 A is investigated on the basis of a time-dependent three-dimensional gasdynamic model. The computational algorithm uses the splitting in the spatial variables. The calculations are parallelized using the graphics card of a personal computer. The dynamics and the special features of the electric arc formation are studied for both gases. In the air the electrically conductive arc column is distributed in shape. In the argon a contracted conducting channel bent toward the flow direction is formed. It is established that the factor causing the differences in the process of electric arc formation in air and argon is the difference in their heat-conducting properties.