Generalized optical theorem to a multipole source excitation in the scattering theory

In the present paper, the Optical Theorem is generalized to the case of a penetrable obstacle excited by a multipole of arbitrary order in the presence of a transparent substrate. This generalization allows one to test computer modules when wave scattering by lossless penetrable obstacle is considered. Besides, it enables one to evaluate the absorption cross-section by subtracting the scattering cross-section from the extinction cross-section. This seems to be important because, in this particular case, the far field does not involve a Sommerfeld integral.     

Catalytic Activity of Nickel Nanoparticles in the Reaction of Reduction of Nitroarenes

Techniques for the production of nickel and nickel-cobalt nanoparticles and of their composites with polyvinylpyrrolidone were developed. The catalytic activity of the resulting compounds towards reduction of substituted nitroarenes was examined.     

Numerical simulation of fracture of ZrO<Subscript>2</Subscript>-Al<Subscript>2</Subscript>O<Subscript>3</Subscript> ceramic composites

The regular grid generation method was generalized for a 3D region based on the solid mechanics equations that describe deformation of a finite volume. Test calculations of fracture of ceramic composites with inclusions are represented which are based on the developed model of quasi-brittle media with regard to damage accumulation.     

Synthesis and crystal structure of mononuclear nickel(II) trifloroacetate complex

Russian Journal of General Chemistry -     

Measurement of O(^1D) formation during thermal decomposition of CO_2 behind shock waves

Atomic Resonance Absorption Spectroscopy (ARAS) was applied to measure the time dependent concentration of electronically excited O(D)-atoms during the thermal decomposition of CO behind reflected shock waves. The experiments were performed in the temperature range 4102 K T 6375 K at pressures 0.2 to 1.9 bar with initial gas mixtures of 100 to 1000 ppm CO diluted in Ar. The measured O(D)-formation rate at early reaction times divided by the initial reactant concentrations was found to obey the Arrhenius law: The assumption of a fast thermalisation between the O(P) and O(D) states is in agreement with previous measurements of the O(P) formation during the thermal decomposition of CO, see Burmeister and Roth (1990). Received 24 January 1995 / Accepted 13 March 1996     

Hypersonic flow past blunt-edged delta wings

A method is proposed for calculating hypersonic ideal-gas flow past blunt-edged delta wings with aspect ratios = 100–200. Systematic wing flow calculations are carried out on the intervals 6 M 20, 0 20, 60 80; the results are analyzed in terms of hypersonic similarity parameters.Translated from Izvestiya Akademii Nauk SSSR, Mekhanika Zhidkosti i Gaza, No. 5, pp. 175–179, September–October, 1990.     

Molecular dynamics simulation analysis of small-angle neutron scattering by a solution of stearic acid in benzene

Data of small-angle neutron scattering by a diluted solution of stearic acid in deuterated benzene have been analyzed using the results of molecular dynamics simulation. The molecular dynamics simulation approach has been used to calculate the time-averaged distribution of the neutron scattering length density at the interface between the acid molecule and the solvent. It has been shown that the organization of the solvent at the interface with the acid molecule leads to a modulation of the neutron scattering length density and makes a significant contribution to the scattering. This contribution should be taken into account when interpreting the experimental small-angle neutron scattering curves for both the considered system and its analogues.     

2-Approximation algorithm for finding a clique with minimum weight of vertices and edges

The problem of finding a minimum clique (with respect to the total weight of its vertices and edges) of fixed size in a complete undirected weighted graph is considered along with some of its important subclasses. Approximability issues are analyzed. The inapproximability of the problem is proved for the general case. A 2-approximation efficient algorithm with time complexity O(n ²) is suggested for the cases when vertex weights are nonnegative and edge weights either satisfy the triangle inequality or are squared pairwise distances for some point configuration of Euclidean space.     

Pretreatment-free immunochromatographic assay for the detection of streptomycin and its application to the control of milk and dairy products

A rapid pretreatment-free immunochromatographic assay was developed for the control of the streptomycin (STR) content in milk and dairy products. The assay is based on the competition between an immobilized STR–protein conjugate and STR in a sample to be tested for the binding to monoclonal anti-STR antibodies conjugated to colloidal gold during the flow of the sample along a membrane strip with immobilized reactants. It is possible to improve the cut-off level of positive and negative samples distinguished by a change in the molar STR to protein ratio in the immobilized conjugate. The cut-off level (500 ng mL⁻¹) thus achieved corresponds to the stated MRL of STR in milk and dairy products. For STR concentrations in the range of 16–250 ng mL⁻¹ its content can be quantitatively measured based on the degree of binding of a colloidal gold label in the test strip zone with the immobilized STR–protein conjugate. The duration of the assay is 10 min. The selected sizes of membrane pores and colloidal gold particles allow the assay to be carried out at room temperature without additional reactants and pretreatment. The applicability of the assay for milk, whole milk, sour clotted milk, and kefir with different fat content (from 0.5% to 6%) was confirmed. The results of quantitative immunochromatographic assay show good correlation with traditional ELISA (r was equal to 0.935 and 0.940 for the series tested).