Radioanalytical monitoring of the formation of barium sulfate in aqueous solutions

The formation of barium sulfate in aqueous media causes problems of insoluble scale formation. On the other hand, the coprecipitation of uranium and transuranium elements with barium sulfate has been suggested for the determination of these elements in environmental monitoring processes. Therefore, the study of barium sulfate crystal growth is required. The investigations done so far suffer from the low sensitivity of the analytical methods used. In the present work we have overcome this problem by using¹³¹Ba for the preparation of supersaturated solutions. Thus kinetics parameters such as induction time and precipitation rates were measured. The polynuclear mechanism was found to be operative at high and the spiral growth at low supersaturations.     

Light transmission by polymer-dispersed liquid crystals

Light transmission of nematic liquid crystals dispersed in a polymeric matrix is investigated. The paper gives a theoretical analysis of light transmission by the liquid crystal-polymer and liquid crystaldye-polymer systems based on determination of the total cross section of extinction. The mathematical model is considered in the anomalous diffraction approximation. The theoretical calculations are in good agreement with experimental data obtained for films based on cyanodiphenyl dispersed into a polyvinyl acetate matrix.Institute of Theoretical and Applied Mechanics, Siberian Branch, Russian Academy of Sciences. Translated fromZhurnal Strukturnoi Khimii, Vol. 34, No. 6, pp. 118–122, November–December, 1993.Translated by L. Chernomorskaya     

Application of energy dispersive X-ray fluorescence spectrometry for the determination of some inorganic pollutants in gravitation dust sediments

Energy dispersive X-ray fluorescence spectrometry with radionuclide excitation has been applied to determine As, Cu, Fe, Pb, Rb, Sr, Ti, Zn and Zr in inorganic pollutants of gravitation dust sediments. Application of this technique required a complete optimization including sampling and their preparation for analysis and evaluation. This method has been finally used to analyze series of samples of dust sediments.     

Absorptive corrections to structure functions at small-x

The role of corrections due to the interactions between different branches of parton (gluon) cascades is studied. It is shown that at HERA energies these interactions increase the absorptive (two-Pomeron cut) contributions by about 60 to 80% compared with the Gribov-Levin-Ryskin equation.This work was supported, in part, by a Soros Foundation Grant awarded by the American Physical Society     

Temperature dependence of the efficiency at which electrons are captured into axial channeling

A procedure for calculating the efficiency at which electrons are captured into axial channeling with a realistic axis potential is discussed. That region in the space of the electron's total transverse energy E and angular momentum L (integrals of motion) which corresponds to stable bound states of the electron with an atomic row is found. The temperature dependence of the capture coefficient is analyzed. As the crystal temperature is increased, the capture coefficient decreases, to a particularly noticeable extent for beams making a small angle with the crystallographic axis and for crystals having a high atomic number z.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 5, pp. 69–74, May, 1988.