Fluctuations of the energy absorption of electron-photon radiation in a model with collision-grouping elements

In the present work, the general method proposed earlier for calculating the distribution density and moments of the absorbed energy in isolated sensitive regions of absorbers irradiated by ionizing particles is developed and made specific for the electron-photon problem. Electron transfer is considered within the framework of a model using grouping of excitations and slipping ionization; the presence of electron equilibrium in the vicinity of sensitive regions is assumed. Two similar methods of calculating these characteristics are developed. Both reduce the initial problem to two independent problems: determining the electron spectrum in the sensitive region (in one of the methods, the spectrum of electron sources is also needed) and calculating the coefficients characterizing electron transfer in the sensitive region and its immediate vicinity.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 9, pp. 89–94, September.     

Calculation of microdosimetric characteristics in electron and gamma-ray irradiated water

The results of a calculation of the characteristics of fluctuations in the absorption of energy of electrons and gamma rays in small sensitive volumes of a material in electronic equilibrium are presented. The calculations were performed by the method developed in [1]. The efficiency and accuracy of the method are demonstrated by comparisons with the experimental results and direct numerical simulation. The experience gained in using the method is analyzed. The main numerical result of this work is a table of coefficients enabling the calculation of the probability of the absorption of energy and the first two moments of the energy absorbed in spherical regions with radii of 1, 2, 4, and 8 m, starting only from the electronic spectrum in these regions, for water absorbers with arbitrary shape and arbitrary electronic or photonic sources with energies up to 1 MeV.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 2, pp. 77–82, February, 1988.     

Coordination of aza heterocycles with macroheterocyclic metal complexes in amphiprotic media: III. Kinetics and mechanism of inner-sphere ligand exchange in (tetraphenylporphyrinato)chromium(III)

Inner-sphere replacement of alcohols by imidazole and its derivatives in the complex (acetato)-(tetraphenylporphyrinato)chromium(III) was studied by electronic absorption spectroscopy. The rate constants and activation parameters of the process were calculated. The entering ligand structure was shown to affect the reaction rate, while the alcohol nature (departing ligand) does not influence the kinetic parameters of the process to an appreciable extent. Regression analysis revealed participation of imidazole and ethanol in the rate-determining stages. The kinetic equation for the inner-sphere axial substitution implies interaction of a free alcohol molecule with that coordinated to chromium, followed by replacement of the associate by the heteroring. Mathematical processing of the kinetic data in terms of the proposed solvolytic association-dissociation mechanism gave the rate constants for particular stages of the process and showed an extremal relation between the rate constant and composition of the solvent.     

Study of the possible isomerization of the phenyl radical employing the nonempirical MO LCAO SCF method

Conclusions Prototropic rearrangement in the phenyl radical cannot proceed under ordinary conditions in view of the high energy barrier.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 2, pp. 460–462, February, 1979.     

Alkylation of 4-aminopyridine

4-Alkylaminopyridines are formed by the alkylation of 4-aminopyridine with cyclohexanol, cyclopentanol, and 2-propanol in sulfuric acid.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 5, p. 631, May, 1971.     

Resonance electron capture by substituted cyclopropane molecules

Conclusions The fragmentation of substituted cyclopropanes under the conditions of dissociative electron capture is accompanied by the opening of the cyclopropane ring and is determined by the nature of the functional group. The increase in the number of electron-acceptor substituents noticeably stabilizes the molecular negative ions.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 11, pp. 2473–2478, November, 1987.     

Investigation of the state of a symmetrical tert-butyl-substituted macroheterocyclic compound in solution by PMR spectroscopy

The PMR spectra of the macroheterocyclic compound obtained by the reaction of 5-tert-butyl-1,3-diiminoisoindoline with 1,3-phenylenediamine in refluxing butyl alcohol and purified by chromatography on aluminum oxide were recorded. It is shown that the compound does not contain a unified conjugated macroring system. The dependence of the chemical shift of the protons of the endocyclic imino groups on the nature of the solvent was investigated. It is shown that the formation of compound-solvent intermolecular hydrogen bonds is complicated by steric factors.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 1, pp. 62–64, January, 1981.     

Alkylation of aminothiazoles; IV. Alkylation of 2-amino-4,5-dimethylthiazole

Alkylation of 2-amino-4,5-dimethylthiazole with isopropanol and cyclohexanol in 85% sulfuric acid gives good yields of isopropylamino- and 2-cyclohexylamino-4,5-dimethylthiazole. The structures of the products are demonstrated by reverse synthesis from 3-chlorobutanone and substituted thioureas.For Part III see [1].     

Condensed and bonded quinoxalines

2-Chloro-3-formylquinoxaline was synthesized from 2-chloro-3-methylquinoxaline by the Kröhnke method, and the properties of its phenylhydrazone were studied. It was found that 2-Y-3-formylquinoxalines display an anomalously low reactivity as compared with 2-Y-benzoylquinoxalines (Y=H, OH, Cl) in the synthesis of pyrazolo[3,4-b]quinoxalines.See [1] for communication IV.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 6, pp. 852–856, June, 1973.     

Conformational state of benzilidene aniline derivatives from ab initio calculation and NMR spectroscopy data

Quantum chemical calculations of the structure and conformational state of a number of Shiff bases have been performed. ¹³C NMR spectra of investigated molecules were calculated and compared with experimental data to test verification of the used calculation model. The effect of terminal substituents on the conformation of azomethines and a relation between the conformation and ¹³C NMR chemical shift were examined.