A solution of an inverse problem for the wave equation with non-linear conditions in domains with moving boundaries

A new approach is proposed for solving problems with moving boundaries. Assuming spherical symmetry, wave phenomena are considered in the case of a surface, of arbitrary initial radius, moving in a compressible medium at a velocity governed by an arbitrary law. Formulas suitable for solving both the inverse and direct problems are obtained.     

Synthesis and molecular structure of 1-(pyrimidin-2-yl)-2-(4-aryl-1,3-thiazol-2-yl)hydrazines

Reactions of some 2-hydrazinopyrimidine hydrochlorides with potassium thiocyanate gave 1-(pyrimidin-2-yl)thiosemicarbazides which underwent Hantzsch condensation with aryl chloromethyl ketones to produce 1-(pyrimidin-2-yl)-2-(4-aryl-1,3-thiazol-2-yl)hydrazine hydrochlorides. The protonation was accompanied by mutually dependent tautomeric rearrangements of heterocyclic fragments.     

Quantum Chemistry,NMR Spectroscopy,and Single-Crystal Diffractometry Methods in the Analysis of Protonation Pathways of 2-Amino-4-benzylsulfanyl-6-methylpyrimidines

Russian Journal of General Chemistry - Protonation pathways of 2-amino-4-benzylsulfanyl-6-methylpyrimidines have been investigated by means of semiempirical PM3 quantum-chemical simulation, 13C NMR...     

Synthesis of 2-(Pyrazol-1-yl)pyrimidine Derivatives by Cyclocondensation of Ethyl Acetoacetate (6-Methyl-4-oxo-3,4-dihydropyrimidin-2-yl)hydrazone with Aromatic Aldehydes

2-(4-Arylidene-3-methyl-5-oxo-4,5-dihydropyrazol-1-yl)-6-methylpyrimidin-4(3H)-ones were obtained by reaction of ethyl acetoacetate (6-methyl-4-oxo-3,4-dihydropyrimidin-2-yl)hydrazone with aromatic aldehydes. Successful cyclization occurs with aldehydes containing an auxochromic substituent in the para position.     

Polyfunctional isocytosine derivatives: II. Regioselectivity of methylation of 2-(2-hydroxyethylamino)-6-methylpyrimidin-4(3H)-one in different media

High regioselectivity in the methylation of 2-(2-hydroxyethylamino)-6-methylpyrimidin-4-(3H)-one at the N³ atom in water and ethanol in the presence of inorganic bases is determined by participation of the oxygen atom in hydrogen bonding and its coordination to metal cation, respectively. In going to aprotic dimethylformamide which is capable of solvating cations, the regioselectivity decreases, and a mixture of N ³-and O-methyl isomers is formed.     

Angular intensity distribution of scattered light in systems of closely spaced particles

The results of experimental and computational investigations of the dependence of the angular intensity distribution of scattered light on the concentration of scatterers are discussed. It is shown that a high density of small and large scatterers in a three-dimensional system results in a deformation of the scattering indicatrix. The changes in the angular distribution of intensity of the scattered light at large concentrations are explained by the appearance of fields of multiply scattered waves at significantly lower optical thicknesses than for independent scatterers.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 3, pp. 99–103, March, 1976.     

Unified Synthetic Approach to 2-Substituted 6-Methylisocytosines and Their 5-Bromo Derivatives

6-Methyl-4(3H)-pyrimidinones containing 2-alkyl-, 2-cycloalkyl-, and 2-arylalkylamino groups were synthesized and brominated to obtain 5-bromo derivatives.     

Synthesis and biological activity of the 2-amino-4-(4-iodophenyl)amino-6-methylpyrimidine isosteric analogs

Transformation of the structure of 6-methylisocytosine results in the isosteric analogs of 2-amino-4-(4-iodophenyl)amino-6-methylpyrimidine exhibiting tuberculocidal properties. The level of biological activity of the synthesized compounds depends on the site of location of the halogen atom.     

5-Arylideneaminouracils: I. Synthesis and relations between physicochemical parameters and biological activity

A number of 5-arylideneaminouracils were synthesized by condensation of 5-aminouracil with substituted aromatic aldehydes. Correlation analysis according to Hantzsch revealed strong effects of the lipophilicity parameter and hydration energy of these compounds on their biological activity.