Magnetism in disordered magnetic Fe82−xNixCr18

The zero field μSR-method has been used to study the magnetism in the disordered magnetic alloy Fe_82−xNi_xCr₁₈ near the three-critical, pointx=25. The dynamic and static local field distributions are analyzed. The difference between spin-glass states obtained either from the paramagnetic or after the double transition is discussed.     

Homo- and heterochirality of dissymmetric tetrahedra (chiral simplices). Stereochemical tunneling

This paper examines the possibility of classifying chiral simplices into homochiral subclasses. It is shown that chiral simplices can skip achiral intermediates to be transformed into another type of homochiral moleucles (stereochemical tunneling). A. V. Bogatskii Physiochemical Institute, Ukrainian Academy of Sciences. Translated fromZhurnal Strukturnoi Khimii, Vol. 36, No. 5, pp. 873–878, September–October, 1995. Translated by L. Smolina     

Topological analysis of the structure-mesomorphous property ralationship

The use of topological indices to reveal the relationship between molecular structure and mesomorphous properties is discussed. Mathematical models for classification of mesophase types are proposed. The effect of molecular structure and attractive ability on phase transition temperatures is described. Examples of using correlation equations to predict the properties of 2,5-disubstituted 1,3-dioxanes are given. A. V. Bogatskii Physicochemical Institute, Ukrainian Academy of Sciences. Translated fromZhurnal Struktumoi Khimii, Vol. 35, No. 4, pp. 53–60, July–August, 1994. Translated by L. Smolina     

Analysis of molecular chirality using the lattice model of spatial structure

A lattice model of the spatial structure of a molecule is suggested. A broken line is constructed to characterize atoms and molecular fragments. The line is a spiral (left or right) embracing the whole lattice containing the molecule. The mutual arrangement of molecular fragments along the broken line is described by a molecular code. The code contains all the necessary information about molecular conformation and configuration in compressed form. Comparing the codes makes it possible to evaluate the structural similarity and dissimilarity of molecules. For example, one can easily estimate the chirality level for enantiomers. Using this approach is demonstrated on various model structures. A. V. Bogatskii Physicochemical Institute, Ukrainian Academy of Sciences. Odessa State University. Translated fromZhurnal Strukturnoi Khimii, Vol. 39, No. 3, pp. 541–546, May–June, 1998. This work was supported by INTAS grant INTAS-UA 95-0060.     

Stereochemical analysis by simplex representation of molecules

Stereoanalysis of molecules by partitioning a spatial structure into a system of simplices is described in detail. Potentialities of simplex representation of molecules in defining stereochemistry are demonstrated for chiral structures of various complexity and planar unsaturated molecules (“two-dimensional stereochemistry”). A concept of “stereochemical charge” is introduced. A. V. Bogatskii Physicochemical Institute, Ukrainian Academy of Sciences. Odessa State University. Translated fromZhurnal Strukturnoi Khimii, Vol. 39, No. 3, pp. 553–558, May–June, 1998.     

μSR study of vortex structure mobility and penetration depth in Bi2Sr2CaCu2O2-δ textured sample

The giant mobility of the magnetic flux in FrFC and ZFC conditions have been studied in textured sample Bi₂Sr₂CaCu₂O_2- bySR. The comparison of results obtained in both cases showed that it is difficult to explain this phenomenon by only thermally activated flux creep and the melting of vortex lattice must be considered. The magnetic field dependence of the melting temperature was obtained for H<90mT. It is shown that the possibility of vortex motion does not affect the results of FC-measurements.     

Stereoanalysis of fullerenes with a chiral molecular framework

Stereoanalysis of three fullerene molecules with a chiral molecular framework C₃₂, C₇₆, and C₇₈ and achiral fullerene C₆₀ molecule was carried out. Comparative quantitative analysis of the degree of chirality showed topology to be the major factor governing the chirality of fullerenes. A procedure for determining the relative contribution of topological chirality to the total chirality of the molecule is proposed. Structural fragments responsible for chirality are found. The title fullerenes are assigned to the corresponding subclasses of homochirality. A classification system of isomeric fullerenes is proposed.     

Detailed equilibrium principle in reversible bimolecular diffusion-controlled reactions

The expressions for the observed rate constants of the forward bimolecular and back monomolecular reactions have been obtained using the boundary conditions imposed upon the reaction surfaces of each reagent particle. The rate, equilibrium and thermodynamical parameters of the back dissociation reactions of phenoxy radical dimers have been measured. The resultant values of k^obs_?1 as a function of solvent viscosity are accurately described by theoretical relationships obtained in the present work.