Effect of clustering in LaCa(Sr)MnO epitaxial films on their magnetic,electron, and optical properties

This work is aimed at finding a correlation between the magnetic properties, conductivity, and crystal structure of La_0.6Sr_0.2Mn_1.2O₃ and La_2/3Ca_1/3MnO₃ films prepared by pulsed laser (KrF) deposition in order to study the behavior of their M(T) and M(H) magnetizations. X-ray diffraction is used to investigate the cluster crystal structure of the manganites. It is shown that the variation of growth temperature and substrate type, along with laser irradiation, change not only the matrix structure (long-range order in ion arrangement) but also the cluster structure (mesoscopic order). The magnetic, electron, and optical properties revealed experimentally are explained by changes in the atomic and electron subsystems of the cluster structures, which provide magnetic interaction between clusters.     

Studies in the imidazole series

A new synthesis of derivatives of thiazolo[3,2-a]benzimidazoles based on 2-halogenobenzimidazoles has been performed. The reaction of 2-chlorobenzimidazole with -halogeno ketones and the subsequent heating of the resulting 1-acylmethyl-2-chlorobenzimidazoles with thiourea has given 1-acylmethyl-2-mercaptobenzimidazoles. The cyclization of the latter under the action of mineral acids or water-abstracting agents has given a series of 2-alkyl-, 2-aryl-, and 2-heteryl-substituted thiazolo[3,2-a]benzimidazoles.For Communication XLIX, see [1].Translated from Khimiya Geterotsiklicheskikh Soedinenii, Vol. 6, No. 6, pp. 827–831, June, 1970.     

On Invariant Tori for a Stochastic Ito System

By using the Green function, we obtain conditions implying existence of invariant sets for Ito systems that are extensions of dynamical systems on a torus.     

Measure of reducible difference systems

We consider a difference system with quasiperiodic coefficientsx _n+1=Ax _n+P(_n)x_n, _n+1=_n+ An estimate is obtained of the measure of the set of those matrices A for which the given system is reducible to a system with constant coefficients.Translated from Ukrainskii Matematicheskii Zhurnal, Vol. 42, No. 11, pp. 1572–1575, November, 1990.     

Representations of *-algebras with two generators and polynomial relations

It is shown that all * -algebras with two generators with quadratic relations are tame and a classification of their representations is given. A number of examples of general polynomial relations are analyzed (the algebras here can be either tame or wild).Translated from Zapiski Nauchnykh Seminarov Leningradskogo Otdeleniya Matematicheskogo Instituta im. V. A. Steklova, Akad. Nauk SSSR, Vol. 172, pp. 121–129, 1989.     

On pairs of unbounded self-adjoint operators satisfying an algebraic relation

Unbounded pairs of self-adjoint operatorsA andB satisfying the algebraic relationF ₁(A)B=BF ₂(A) are studied. For these relations, various definitions of integrable pairs of operators are presented and the class of tame relations is indicated; for the tame relations, the irreducible pairs are described and a structure theorem is presented.Translated from Ukrainskii Matematicheskii Zhurnal, Vol. 45, No. 9, pp. 1253–1258, September, 1993.     

Reaction of 3-oxo-N-phenylbutanethioamide with 5-amino-1H-1,2,4-triazoles

Reactions of 3-oxo-N-phenylbutanethioamide with 3-substituted 5-amino-1H-1,2,4-triazoles in acetic acid led to the formation of 5-methyl-7,8-dihydro[1,2,4]triazolo[1,5-a]pyrimidine-7-thiones, 7-methyl-5,8-dihydrol[1,2,4]triazolo[1,5-a]pyrimidine-5-thiones and 7-methyl-5-phenylamino[1,2,4]triazolo[1,5-a]pyrimidines. The structure of the products was proved by the ¹H and ¹³C NMR spectra, X-ray diffraction data, and chemical transformations.     

Cycloaddition in condensed isoindoles 1. Preparation of 2-aryl-3-methyl-4-oxo-3,4-dihydroquinazoline

Reaction of 6-methyl-5,6-dihydroisoindolo[2,1-a]quinazolin-5-one with maleimide derivatives has been studied under conditions of thermodynamic control. X-ray diffraction structural analysis showed that the reaction products are 2{2-[(E)-1-R-2,5-dioxopyrrolidinidenemethyl]phenyl}-3-methyl-4-oxo-3,4-dihydroquinazolines. These products are supposed to be formed by rearrangement of the corresponding Diels-Alder adducts formed involving the isoindole part of the molecule. Taras Shevchenko Kiev University, 252033 Kiev, Ukraine; Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 5, pp. 669–677, May, 1999.     

Igor Volodymyrovych Skrypnik (On His 60th Birthday)

Ukrainian Mathematical Journal -