Oxidative bromination of isoprenyl units of butyl rubber with the hydrobromic acid-sodium hypochlorite system

Synthesis of bromo butyl rubber using the hydrobromic acid-sodium hypochlorite system as brominating agent was studied.     

Luminescence and electrical conductivity of KCl-PbCl2 crystals grown from aqueous solutions

Luminescence spectra of KCl-PbCl₂ crystals grown from aqueous solutions are compared with those of KCl-PbCl₂ crystals grown from a melt. It is found that at PbCl₂ concentrations C > 3·10^–3 mole % there appears in the luminescence spectrum of solution-type crystals a new band with a peak at the 365-nm wavelength, which has never been noted in the case of melt-type crystals. The appearance of this band is attributed to (PbCl_n)^–(n–2) complexes entering the crystals when the latter are grown from solutions. The concentration characteristics of ion conductivity are analyzed here and seem to confirm the hypothesis of this complex formation.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 8, pp. 31–35, August, 1974.     

Analysis of dispersion characteristics of phononic structures

A general theory for calculating the dispersion of bulk acoustic waves in 3D and 2D phononic crystals made of anisotropic materials is presented, which is based on the plane-wave expansion method. Two approaches to separating acoustic modes in the dispersion diagrams are proposed. The pattern of the acoustic field distribution is studied as depending on the wavevector direction for various types of modes. Degeneracy of acoustic modes in directions different from the axes of symmetry of the phononic crystal is demonstrated. Possibilities of the proposed method are illustrated by the application to 3D and 2D silicon-based phononic crystal structures.     

Holographic interferometry of liquids at the He-Ne laser wavelength under microwave irradiation

Changes in the optical refractive indices of a number of organic liquids, water, and some biological aqueous solutions exposed to (37.5–78)-GHz electromagnetic radiation have been investigated using a differential holographic interferometer. It is established that irradiation with intensities up to 10 mW/cm² may reduce the refractive index of liquids by ～10^?3 as a result of thermal changes in the dielectric constant of the material studied. The magnitude and dynamics of changes in the refractive index are determined by the irradiation intensity and physical parameters of liquids (dipole moment of molecules, absorption coefficient, permittivity, and temperature coefficient of the refractive index) and are independent (within the experimental error) of the mutual orientation of the polarization unit vectors of the microwave and optical fields.     

Separation of copper and bichromate ions by complex methods

Separation of Cu²⁺ and Cr₂O₇ ^2– has been studied by electrodialysis combined with preliminary adsorption on bentonite. The influence of concentration, pH, and electric current on the degree of desalination has been studied. The optimum conditions for almost complete separation of the ions studied have been found. Real galvanic sewage has been examined by this method.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 7, pp. 1191–1193, July, 1994.     

Deglycosylation of isoflavonoid glycosides from <Emphasis Type="Italic">Maackia amurensis</Emphasis> cell culture by β−D-glucosidase from <Emphasis Type="Italic">Littorina sitkana</Emphasis> hepatopancrease

Maakia amurensis (strain A-18) cell culture synthesizes a significant quantity of isoflavonoids, a large part of which consists of isoflavone glucosides and malonylglucosides. β−D-Hydrolase enzyme complexes from the marine mollusk Littorina sitkana and the marine mycelial fungus P. canescens were used to obtain isoflavones from their conjugated forms. The specificity of β−D-glucanases from L. sitkana for various glycosides was studied. The deglycosylation efficiency depended on the aglycon structure. The deglycosylated fraction of isoflavonoids obtained from M. amurensis cell culture exhibited antitumor activity.     

Oxidative bromination of isoprenyl links of butyl rubber by the system sodium bromide-sodium hypochlorite-phosphoric acid

Results of studying kinetics of the bromination of isoprenyl links of butyl rubber by the system sodium bromide-sodium hypochlorite-phosphoric acid are presented. Reaction orders with respect to the reagents were determined, and the value of the observable activation energy was estimated.