Synthesis and properties of 1,3,4-thiadiazine derivatives. 1. Investigation of the condensation of substituted phenacyl bromides and bromoacetylpyridines with thiosemicarbazide

2-Amino-5-aryl(pyridyl)-6H-1,3,4-thiadiazines ana isomeric 2-hydrazino-4-aryl(pyridyl)thiazoles, the ratio of which depends on the reaction conditions, were obtained by the reaction of substituted phenacyl bromides and bromoacetylpyridines with thiosemicarbazide.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 6, pp. 843–846, June, 1991.     

Heat capacity and physical transitions in collagen and solubility of water in it

The heat capacities of cattle and poultry collagen samples were measured by adiabatic calorimetry in the range 80–330 K. The temperatures of physical transitions in these samples were determined. Endothermic relaxation transitions (γ₁, γ₂, and β) were observed in the heat capacity curves of the studied collagen samples. The solubility of water in collagen samples obtained from various sources was determined by calorimetry from the enthalpy of melting of the “free” water phase.     

Effect of the nature of carboxylate anion on the features of intramolecular hydrogen bonding in [Pd(Hdmpz)<Subscript>4</Subscript>](OOCR)<Subscript>2</Subscript> (R = Me,Bu<Superscript>t</Superscript>, Ph)

We discovered that reactions of [Pd(OOCMe)₂] _n and Pd₃(μ-OOCMe) with 3,5-dimethylpyrazole (Hdmpz) yield mononuclear complex [Pd(Hdmpz)₄](OOCMe)₂, in which acetate anions can exchange for pivalate or benzoate anions in reactions with proper acids. The specifics of intramolecular hydrogen bonding in the complexes prepared are discussed as dependent on the nature of the carboxylate anion using X-ray crystallography data.     

Measurement of thicknesses of thin films by the Fourier spectrometry method

A Fourier spectrometry method for measuring the thickness of thin and ultrathin films with the help of an additional peak that depends on the optical thickness of the deposited film and is situated outside the region of the central peak of the interferogram is proposed. The experiment demonstrates the necessity of considering the change in optical path in the substrate that is induced by the deposited film.     

Propagation of perturbations in a two-layer stratified fluid with an interface excited by moving sources

Propagation of small perturbations in a two-layer inviscid stratified fluid is studied. It is assumed that the higher density fluid occupies the lower unbounded half-space, while the lower density fluid occupies the upper unbounded half-space. The source of the excitation is a plane wave traveling along the interface of the fluids. An explicit analytical solution to the problem is constructed, and its existence and uniqueness are proved. The long-time wave pattern developing in the fluids is analyzed.     

Pyrazolate-bridged binuclear zinc complexes Zn<Subscript>2</Subscript>(μ-dmpz)<Subscript>2</Subscript>(Hdmpz)<Subscript>2</Subscript>(OOCR)<Subscript>2</Subscript> (R = Me,Ph; Hdmpz = 3,5-dimethylpyrazole)

Triethylamine reacts with aqueous zinc acetate and the product of its thermolysis in the presence of benzoic acid to yield the complexes [Zn₇(μ₄-O)(μ-OOCMe)₁₀][η-OC(Me)OHNEt₃]₂ (1) and [Zn₂(μOOCPh)₄][η-OC(Me)OHNEt₃]₂ (2), respectively. The reactions of 1 and 2 with 3,5-dimethylpyrazole at room temperature in benzene yield pyrazolate-bridged binuclear complexes Zn₂(μdmpz)₂(Hdmpz)₂(OOCR)₂ (R = Me (3), Ph (4)). The structures of complexes 1–4 have been determined by X-ray crystallography.     

Influence of maleic anydrate on properties of incongealable sealants based on butyl rubber

The possibility of using butyl rubber modified by maleic anhydrate as an adhesive additive and obtaining incongealable composites on its basis are shown.     

Propagation of perturbations in fluids excited by moving sources

A large series of A.A. Dorodnicyn’s works deals with rigorous mathematical formulations and development of efficient research techniques for mathematical models used in inhomogeneous fluid dynamics. Numerous problems he studied in these directions are closely related to stratified fluid dynamics, which were addressed in a series of works having been published in this journal by this paper’s authors and their coauthors since 1980. This paper describes the results of a series of works analyzing the propagation of small perturbations in various stratified and/or uniformly rotating inviscid fluids. It is assumed that each of the fluids either occupies an unbounded lower half-space with a free surface or is a semi-infinite two-component fluid layer. The perturbations are excited by a moving source specified as a periodic plane wave traveling along the interface of the fluids. Problems for five mathematical fluid models are formulated, their explicit analytical solutions are constructed, and their existence and uniqueness are discussed. The asymptotics of the solution as t → +∞ are studied, and the long-time wave patterns developing in five fluid models are compared.     

A simple method for evaluation of the self-consistency of the radial distribution functions and the orientation of water molecules in the first coordination sphere from the results of molecular dynamics calculations

A simple method for determination of the angular orientation of water molecules in the first coordination sphere from the radial distribution functions is proposed. A comparative analysis of the ability of the model potentials of pair interaction to take into account the effects of manybody interactions (MBI) was performed. The responses of the model pair potentials to the MBI effects in the first and second coordination spheres were found to be poorly correlated with each other. It was concluded that it is necessary to derive a new analytical type of potential functions of pair interaction. Published inIzvestiya Akademii Nauk. Seriya Khimicheskaya. No. 11, pp. 1842–1846. November. 2000.