Resonance effects in a phased antenna array constructed from rectangular waveguides

Translated from Matematicheskie Modeli i Optimizatsiya Vychislitel'nykh Algoritmov, pp. 131–143, 1993.     

Preparation of alkyl-containing derivatives of chitosan and its oligomers in polymer-analogous reactions

It has been shown that the interaction of chitosan and oligochitosan with unsaturated acrylic esters via the nucleophilic addition mechanism and their condensation with heptadecyl isocyanate yield hydrophobic alkyl-containing derivatives of the above polymers. The method of modification of oligochitosan in reactions via end functional groups is developed.     

Covalent immobilization of heparin on a collagen film

Four procedures for the covalent immobilization of heparin (Hp) on a collagen film (CF) have been investigated. In three of them (methods (I–A, B, C), the CF was first treated with epichlorohydrin and ammonia and the Hp was added with the aid of CMBC (method I–A), by reductive amination in the presence of NaCH CN (method I–B), and with the aid of CMEC after succinylation (method I–C). In the fourth procedure (method II), the CF was activated by treatment with alkali and the Hp was added with the aid of CMEC. It was shown that the maximum amount of Hp was immobilized by method II.M. V. Lomonosov Moscow State University. Translated from Khimiya Prirodnykh Soedinenii, No. 5, pp. 700–704, September–October, 1987.     

Interaction of chitosan with benzoic acid in solution and films

Chitosan films are prepared from solutions containing benzoic acid. Depending on preparation conditions, films of two types can be prepared: homogeneous optically transparent films and biphasic films containing fractal inclusions in a transparent matrix. The presence of ionic interaction between chitosan and benzoic acid in films is confirmed with the use of IR spectroscopy. The algorithm of the analysis of fractal dimensionality based on halftone images is suggested.     

Determination of the specific surface area of FORUM fluoroplastic powder by the dye adsorption from solutions

The specific surface area of FORUM fluoroplastic powder, synthesized by the partial thermal degradation of polytetrafluoroethylene followed by the separation of spherical particles from a gas condensate is estimated from the adsorption of two dyes, methylene blue and rhodamine 6G, from aqueous solutions.     

Phenolic compounds ofPotentilla fruticosa

Chemistry of Natural Compounds -     

States of a supersaturated solution in limited-size systems

The features of phase transformations in limited-size systems have been described. The main specificity of small-size systems is the multivariance of equilibrium and metastable states whose stability and region of existence depend on the dimensions of the system, concentration, and temperature. A decrease in the dimensions of the system makes it possible to increase the solubility and to prevent the decay of the supersaturated solution. The properties described by the thermodynamic model are reproduced experimentally using the ensemble of evaporated drops of the solution.     

Generalization of the Chinese remainder theorem

Sufficient conditions for a system Ax = r to have an integral solution in the case of a basic matrix A in terms of submatrices and permanents of A are derived. Matrix A in the Chinese remainder theorem is a particular case of a basic matrix. The derivation can be extended to the case where the propositional formula that describes the sign scheme of A is a minimal unsatisfiable CNF.