Synthesis of the ethyl ester of the mononitrile of malonic acid by the catalytic carbonylation of benzenesulfonyloxyacetonitrile

A new method has been developed for the synthesis of the ethyl ester of the mononitrile of malonic acid by the carbonylation of benzenesulfonyloxyacetonitrile in absolute ethanol in the presence of cobalt carbonyl. The yield of the desired product was 30% with 60–90% conversion of the starting compound. The effects of temperature, pressure, and reaction time were studied.N. D. Zelinskii Institute of Organic Chemistry, Russian Academy of Sciences, 117913 Moscow. S. M. Kirov Urals Polytechnical Institute, Ekaterinburg. Translated from Izvestiya Akademii Nauk, Seriya Khimicheskaya, No. 1, pp. 215–216, January, 1992.     

IR Photolysis of Liquid Hexamethyldisiloxane by Pulse CO2Laser Radiation

The IR photolysis of liquid hexamethyldisiloxane [(CH₃)₃Si]₂O by pulse CO₂laser radiation was studied. The experiments were performed both with and without a graphite powder as a sensitizer. The presence of the graphite sensitizer increases the efficiency of dissociation. To provide the highest penetration of the laser emission into a medium, the irradiation of samples were carried out with tuning far from the maximum of the Si–O bond absorption band (1055 cm^–1) using the 10P16 line (_las= 947.78 cm^–1). This tuning makes it possible to separate the process of IR multiphoton dissociation of the vapor over the liquid phase and to carry out the reaction in the liquid at a low (1 J/cm²) energy fluence of laser radiation. The IR spectra of irradiated liquid samples indicate the formation of linear and cyclic polystructures.     

Laser-spectrochromatographic identification of isomer in mixture

The combined “Gas Chromatograph — Laser Optoacoustic Spectrometer” (GC-LOAS) has been used to perform selective analysis of a mixture of fatty acid esters stereocisomers and a mixture of methylcyclopentadiene positional isomers. The GCLOAS system allows simultaneous recording of the retention time of the components in the mixture under analysis and their IR absorption spectra in the spectral operating range of the ¹²CO₂, ¹³CO₂ and HeNe lasers. It has been shown that the hydrogenated sample of fatty acids contains a lot of trans-isomer. Its content has been quantitatively estimated. The identification of methylcyclopentadiene isomers (both monomers and dimers) has been carried out, too.     

The Root Class Residuality of the Tree Product of Groups with Amalgamated Retracts

Siberian Mathematical Journal - Given a root class $\mathscr{K}$ of groups, we prove that the tree product of residually $\mathscr{K}$ -groups with amalgamated retracts is a residually...     

X-ray fluorescence method for determining the mass absorption coefficient in two-layer thin-film Ti/Ge and Ni/Ge systems

We propose a new method for determining the mass absorption coefficient in x-ray fluorescence analysis of two-layer thin-film Ti/Ge and Ni/Ge systems using easily made standardized film layers obtained by deposition of titanium or nickel on a polymer film substrate. We calculate correction factors taking into account absorption of primary emission from the x-ray tube and absorption of the analytical line for an element of the bottom layer in the top layer.     

Carbamate preparation by nitromethane carbonylation

Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 5, p. 1190, May, 1988.     

Finite-difference schemes for parabolic problems on graphs

We consider a reaction–diffusion parabolic problem on branched structures. The Hodgkin–Huxley reaction–diffusion equations are formulated on each edge of the graph. The problems are coupled by some conjugation conditions at branch points. It is important to note that two different types of the flux conservation equations are considered. The first one describes a conservation of the axial currents at branch points, and the second equation defines the conservation of the current flowing at the soma in neuron models. We study three different types of finite-difference schemes. The fully implicit scheme is based on the backward Euler algorithm. The stability and convergence of the discrete solution is proved in the maximum norm, and the analysis is done by using the maximum principle method. In order to decouple computations at each edge of the graph, we consider two modified schemes. In the predictor algorithm, the values of the solution at branch points are computed by using an explicit approximation of the conservation equations. The stability analysis is done using the maximum principle method. In the predictor–corrector method, in addition to the previous algorithm, the values of the solution at the branch points are recomputed by an implicit algorithm, when the discrete solution is obtained on each subdomain. The stability of this algorithm is investigated numerically. The results of computational experiments are presented.     

Numerical analysis of nonlinear model of excited carrier decay

This paper presents a mathematical model for photo-excited carrier decay in a semiconductor. Due to the carrier trapping states and recombination centers in the bandgap, the carrier decay process is defined by the system of nonlinear differential equations. The system of nonlinear ordinary differential equations is approximated by linearized backward Euler scheme. Some a priori estimates of the discrete solution are obtained and the convergence of the linearized backward Euler method is proved. The identifiability analysis of the parameters of deep centers is performed and the fitting of the model to experimental data is done by using the genetic optimization algorithm. Results of numerical experiments are presented.