The exactly resolved nonlattice model of random media based on Markov walks with a stable law for jumps

A random-medium model which is a correlated distribution of points (particles) randomly positioned in the 3-dimensional space is considered. The construction of the medium starts from a noncorrelated (Poisson) distribution of parent particles, each of them initiates a finite Markov chain of its descendants. The complete collection of correlation functions of all orders within the scope of the model have been obtained. The use of the 3-dimensional stable law (Lévy law) as a transition probability allows us to present the correlation function in an explicit form. Proceedings of the XVII Seminar on Stability Problems for Stochastic Models, Kazan, Russian, 1995, Part II.     

Electronic structures and electrophilic substitution in 2-(4-R-2-quinolyl)thiophenes and 5-(4-R-2-quinolyl)-2,2′-dithienyls

The electronic structures and reactivity indexes (RI) of 2-(4-R-2-quinolyl)thiophenes and 5-(4-R-2-quinolyl)-2,2-dithienyls (R = H, COOH, COOC₂H₅, and NHCOCH₃) and their protonated forms were calculated by the Pariser-Parr-Pople (PPP) method. The peculiarities of the geometrical and -electron structures were established. The calculated reactivity indexes are compared with experimental data on the electrophilic substitution reactions of the investigated compounds. A qualitative agreement between the calculated values and the experimental data was established. It is shown that quinoline derivatives of thiophene are less reactive than the corresponding dithienyl compounds in electrophilic substitution reactions.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 6, pp. 751–754, June, 1979.     

Trialkyl-n-(2-vinyloxyethyl)ammonium salts — New systems akin to acetylcholine

Conclusions Vinyloxyethyltrialkylammonium salts possessing strong hypertensive activity were prepared by reacting 2-(dialkylamino)ethyl vinyl ethers with alkyl iodides and 2-halogenoethyl vinyl ethers with tertiary amines.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 5, pp. 1178–1180, May, 1969.     

Vibronic properties of 2-azaanthracene and its derivatives

We report an experimental and theoretical (PPP method) study of the UV absorption spectra of 2-azaanthracene and four of its methyl-substituted derivatives. We find that the p bands of these compounds consist of two different vibronic ^* bands. Our experimental and theoretical results suggest a rule for evaluating the effect of methyl groups on ^* transition energies as a function of the charge on the atoms. We interpret the reasons for the different effects of a polar solvent and hydrogen bonding on the ^* bands of these compounds.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 6, pp. 7–15, June, 1977.     

Mechanism of Formation of Bi4Ti3O12

The mechanism of solid-phase reaction of Bi₄Ti₃O₁₂ formation was studied. Formation of the layered perovskite-like bismuth titanate occurs via intermediates with sequential changes in the coordination polyhedron of bismuth. A correlation is analyzed between the temperature of the onset of activation of the solid-phase reaction and the melting point of the surface (intergrain) phase based on bismuth oxide.     

Synthesis of solid solutions of double-layered Ruddlesden-Popper phases in the Gd2O3-SrO-Fe2O3-Al2O3 system

The continuous Gd₂Sr(Al_{1 ? x} Fe _x )₂O₇ solid solution series was synthesized by a solid-state route over the entire concentration range (0 < x < 1). The processing stages of Gd₂Sr(Al_{1 ? x} Fe _x )₂O₇ series were investigated, and phase interaction schemes reflecting the multistaged formation of double-layered Ruddlesden-Popper solid solution are constructed. The closeness of the reactive mixture composition to the composition of individual compounds Gd₂SrAl₂O₇ or Gd₂SrFe₂O₇ is of importance for the realization of a particular way of Gd₂Sr(Al_{1 ? x} Fe _x )₂O₇ solid solutions formation.     

Wannier spin excitons in charge-transfer complexes

Electron spin resonance in some charge-transfer complexes of 7,7,8,8-tetracyanoquinodimethane (TCNQ) with sulphanilamides and antibiotics has been investigated. The ESR spectra are caused by two types of paramagnetic centres: the impurity type and the thermally excited type (Wannier spin excitons).     

Correlation-induced double-plasmon excitation in simple metals studied by inelastic x-ray scattering

We report a new type of peaklike structure observed in the tail of the dynamic structure factor of simple metals, measured by inelastic x-ray scattering. Based on the momentum-transfer dependence of the energy position and the intensity of this structure, it has been unambiguously attributed to intrinsic plasmon-plasmon excitations, an electronic correlation effect that was theoretically predicted by many-body perturbation theory of the homogeneous-electron-gas model beyond the random-phase approximation. This signature appears to be largely unaffected by electron-ion interaction effects. Thus a structure that is primarily caused by correlation effects in the electron gas has been found experimentally in the dynamic structure factor of simple metals.