Derivatives of 2H-pyrazolo[4,5-b]-1,4-thiazine

Derivatives of 2H-pyrazolo[4,5-b]-1,4-thiazine, which tend to undergo dimerization at the 2-methylene group were synthesized by reaction of 5-amino-3-methyl-4-thio-1-phenylpyrazole with -bromoacetophenones.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 2, pp. 265–268, February, 1989.     

Intramolecular cyclization involving O-vinyl or O-vinylketoxime function in a number of pentacyclic triterpenoids in superbasic medium

28-Triphenylmethoxylup-20(29)-ene-2,3-dione dioxime and 18α(H)-oleanane-3β,19β,28-triol upon reaction with acetylene in superbasic medium KOH-DMSO undergo intramolecular cyclization with the formation of products containing 1,2,5-oxadiazole and tetrahydrofuran fragment, respectively.     

On the mass of the liquid attached to a moving bubble separated from the electrode surface by a spark discharge

The mechanism of detachment and motion of gas bubbles from the GaAs surface, initiated by a spark discharge in an aqueous electrolyte, is investigated. The model proposed for the displacement of bubbles in the liquid is based on the theory of the formation of a water ram pressed by a gaseous inclusion out of the compacted layer of the liquid as a result of action of the compression wave produced by a spark discharge. The effect of the size and temperature of a gas bubble on the geometrical parameters of the water ram is considered. The lifetime of the water ram is determined from the pressure drop at the leading edge of the compression wave.     

Comparing two modes of control during the growth of a colony of microorganisms

This work examines a biological model that describes the growth of microbial cells. The problem of optimum control is to maximize the amount of structural biomass at the final moment in time. This work studies two control modes. It is shown that starting from a certain point in time, one mode is better than the other in terms of maximizing the structural biomass of the cells.     

Computer analysis of two-dimensional images in the Zernike phase contrast method for hard X rays

The problems of the numerical simulation of two-dimensional images in the Zernike phase contrast method in hard X rays are analyzed. Calculations are performed for experimental conditions typical of third-generation synchrotron radiation sources (ESRF, APS, Spring-8, etc.). Schemes are considered where the focusing elements are a refracting lens and a zone plate and the phase-shifting element is situated at the point of the source image. It is shown that the refracting lens allows better resolution than the zone plate. A technique similar to ptychography can be successfully applied to improve the quality of the images obtained by the Zernike phase contrast method.     

Specific properties of hydroxyapatite as a potential transporter of copper ions and its complexes

Russian Chemical Bulletin - Modification of the cocrystallization method for producing hydroxyapatite (HAP) and an HAP-Cu combination to the enzymatic method using alkaline phosphatase leads to a...     

Kinetics of disilane molecule decomposition on the growth surface of silicon in vacuum gas-phase epitaxy reactors

The range of the characteristic decomposition rates of dihydride molecule radicals adsorbed by the silicon surface in the temperature interval 450?C700°C is experimentally found for a number of kinetic models. A relationship between the rate of silicon atom incorporation into a growing crystal and the characteristic rate of disilane molecule pyrolysis on the silicon surface is found. The temperature dependence of the rate of disilane fragment decomposition on the silicon surface is nonmonotonic, and its run depends on temperature conditions. It is shown that the temperature dependence of the molecular decomposition rate on the growth surface is described by a superposition of two activation curves with various activation energies. The activation energies depend on the peculiarity of interaction between the molecular beam and the silicon surface when the filling of surface states with hydrogen is low and high.