Unsteady motions of dense envelopes generated by ionization-shock fronts in the interstellar medium

The process of formation and acceleration of a neutral gas envelope during the propagation of an ionization-shock front in a spherical gas cloud is numerically modeled. The velocity and acceleration of the envelope as well as its mass variation with time are determined. The results obtained are compared with some approximate formulas known in the literature. The growth of small velocity perturbations in the dense gas and the effects of mass and momentum accumulation in “finger-like” condensations are studied in the framework of a two-dimensional model.     

Dynamics of Backscattering of Human Tissue on Exposure to a Low-Intensity Optical Radiation

The results of in vivo experiments on the spectral response of a human organism to the action of low–intensity optical radiation are presented. The dynamics of backscattering of diagnostic radiation in infrared and red spectral regions was recorded. The characteristic types of response to exposure have been revealed: a sudden increase or decrease in the value of the relative coefficient of backscattering accompanied by saturation.     

Untersuchung der Struktur und Eigenschaften der Polymeren des 2-Methyl-5-?thinylpyridins

Ohne Zusammenfassung     

Synthesis of 2-(1-alkoxyvinyl)pyridines

2-(1-Bromovinyl)pyridine, 2-ethynylpyridine, 2-(1-alkoxyvinyl)pyridines, and 2-(2-alkoxyvinyl)pyridines (the cis and trans isomers) were detected in the reaction mixture by mass spectrometry in the reaction of 2-vinylpyridine with bromine with subsequent dehydrobromination of the addition product with an alcohol solution of alkali. The conditions for the preparation of chromatographically pure compounds were found.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 5, pp. 647–650, May, 1978.     

Peculiarities of pluronic crystallization in thin films

The peculiarities of the crystallization of Pluronics from chloroform and aqueous polymer solution on mica surfaces are investigated with the atomic force microscopy method. It is shown that Pluronics in thin films form quasi two-dimensional crystalline structures of 10–12 nm thickness. Pluronic crystallization proceeds predominantly via the mechanism of diffusion-limited aggregation with the formation of dendrites. Three main morphological types of formed structures are identified including two types of dendrites (with 45° and 90° angles between branches) and elongated “needles.” It is shown that the film morphology depends on the polymer concentration, rate of solvent evaporation, and, probably, local gradients of concentration and temperature. Interaction with porphyrins establishes conditions for the local three-dimensional crystallization of Pluronics.     

A dynamic array of optical traps for deformation of elongated microobjects

A simple technique for the formation of an array of laser traps on the basis of phase diffraction gratings is proposed. The array allows trapping transparent elongated microobjects at several points simultaneously. The dynamic variation in the spatial disposition of the traps makes its possible to impose deformation on a trapped microobject. The technique proposed has been experimentally tested.     

The mutual influence of imino acids and phenylalanine on the dynamic characteristics of sorption on KU-2 × 8 sulfocation exchanger in the H form

The dynamics of sorption of pure imino acids (proline and hydroxyproline) and imino acids in the presence of aromatic amino acid, phenylalanine, on KU-2 × 8 sulfocation exchanger in the H form was studied. Mutual influence of amino acids on the dynamic characteristics of sorption was observed. This influence changed the shape of elution curves and decreased the working exchange capacity. Both competitive and synergistic sorption mechanisms governed sorption of amino acids from binary solutions.     

Diffractive elements based on spiral beams as devices for determining the depth of bedding of radiation sources

A modified iteration method is proposed for calculations in developing diffraction optical elements for the generation of rotating light fields. The main feature of the proposed approach is the use of the spiral light beam theory for selecting the initial phase approximation. The diffractive optical elements under study could be used in microscopic analysis of the spatial location of different objects.     

The thermodynamic characteristics of formation of alloys in the Ge-Ga-Mn and Si-Ni-Al systems

The enthalpies of mixing of ternary system melts were determined by high-temperature calorimetry under isoperibolic conditions. For the Ge-Ga-Mn system, measurements were taken at 1780 ± 5 K along five ray sections with constant ratios between the atomic fractions of germanium and gallium up to a ～0.6 mole fraction of manganese; the x _Ge/x _Ga ratios were 0.8/0.2, 0.7/0.3, 0.5/0.5, 0.3/0.7, and 0.15/0.85. For the Si-Ni-Al system, measurements were taken at 1770 ± 5 K along five ray sections with constant ratios between the atomic fractions of silicon and nickel up to a ～0.6 mole fraction of aluminum; the x _Si/x _Ni fratios were 0.85/0.15, 0.7/0.3, 0.5/0.5, 0.3/0.7, and 0.15/0.85. The formation of melts in these systems was found to be exothermic over the composition range studied. The integral enthalpies of melt formation were maximum along the x _Ge/x _Ga = 0.8/0.2 section in the Ge-Ga-Mn system (?18.8 ± 3.3 kJ/mol) and along the x _Si/x _Ni = 0.5/0.5 section in the Si-Ni-Al system (?67.8 ± 3.4 kJ/mol). An analysis of the isolines of the integral enthalpies of mixing led us to conclude that the Ge-Mn and Ga-Mn binary systems had the strongest influence on the thermodynamic characteristics of melt formation in the Ge-Ga-Mn system, the predominant influence being that of the Ge-Mn binary system. An analysis of the energy characteristics of melt formation in the Si-Ni-Al ternary system showed that the major contribution was made by the interaction of components in the Si-Ni and Ni-Al boundary binary systems, the influence of the Si-Ni system being stronger.