Intra-Nuclear Cascade (INC) code for simulation of meson photoproduction in nuclei

η meson photoproduction in the ¹⁴N nucleus was studied using simulations done with INC (Intra-Nuclear Cascade) code. The probability for mesons and nucleons to escape the nucleus on different steps of the reaction was evaluated. These results predict the possibility of studying elastic and inelastic η meson interactions with intra-nuclear nucleons using the recoil proton as a tag for the case of slow η meson and fast recoil proton.     

The Application of Adhesive Technologies in the Assembly of Antivibration Boring Arbor

The design of an antivibration boring arbor that includes an adhesive joint and the technological process of its assembly are developed. It is shown that the use of an adhesive joint allows one to significantly reduce the labor intensity of the assembly process of such arbors and their cost price, as well as to decrease the vibrations of a tool.     

Determination of the critical parameters of polymer solutions

The contribution of short-range orientation order to the chemical potentials of components in a polymer-solvent system was determined. The temperature dependence of the degree of orientation of solvent molecules relative to polymer chains in a polyisobutylene-benzene system was obtained. It was shown that the short-range order in the polymer-solvent system fails with temperature to a much lesser extent than in the pure solvent. The expressions for the upper and lower critical solution temperatures with allowance for the contribution of short-range order to the entropy and the free energy of solution, as well as to the chemical potentials of components, were found. It was demonstrated that, in the polymer-solvent system, two upper and two lower critical solution temperatures can exist.     

Preliminary results of the cross-section measurement of e<Superscript>+</Superscript>e<Superscript>−</Superscript> → φ(1020)η process with the CMD-3 detector at VEPP-2000 collider

We report preliminary results on the cross section of the process e⁺e^? → φ(1020)η measured at 30 center-of-mass energy points in the range from 1.59 up to 2.0 GeV. Data analysis is based on the integrated luminosity of 22 pb^?1 collected with the CMD-3 detector in 2011–2012. The obtained cross section agrees with the BaBar measurement and has better statistical accuracy.     

Quantum-chemical calculation of the thermodynamics of multistep hydrolysis of MX<Subscript>4</Subscript> molecules (M = C,Si, Ge; X = H,F, Cl) in the gas phase

The standard enthalpies, entropies, and Gibbs free energies of separate stages of the multistep hydrolysis of MX₄ molecules (M = C, Si, Ge; X = H, F, Cl) in the gas phase at 298 K were calculated by the G3 high-precision quantum-chemical method of calculation of thermodynamic parameters. The trends in these parameters were analyzed for each group of molecules. The calculated thermodynamic parameters make it possible to estimate the theoretical limits for the contents of water and hydrolysis products in the above high-purity carbon, silicon, and germanium derivatives.     

Intentional selection of coordination compounds with the required thermochemical properties on the basis of the cambridge bank of structural data

A structural-thermochemical analysis of the Cambridge bank of structural data was performed according to specified number and types of intermolecular contacts. The TOPOS package and the SFERA and KONTAKT programs were used to analyze the structure of mononuclear barium molecular complexes containing completely screened barium atoms. Contacts between their molecules are formed by ligand hydrogen, carbon, and fluorine atoms only, whereas contacts of the type barium-barium or barium-any ligand atom of a neighboring molecule are absent. The enthalpies of vaporization of the selected complexes were estimated and a series of their volatility was established. The results were in agreement with the currently available experimental data.     

Mechanism of the Grignard reaction in terms of the cluster model of reaction center. A quantum-chemical study

Most probable paths of the classical Grignard reaction between ethyl bromide and Mg₃₁ cluster simulating the reaction center on the surface of metallic magnesium were analyzed in terms of the density functional theory [B3PW91/6-31G(d)]. Principal thermodynamic parameters of the radical reaction path, including the energy of adsorption of oxidant molecules on the cluster, the energy of formation of ethyl radicals, and the energy of their subsequent interaction with the surface, were calculated. The structure corresponding to the true transition state of the Grignard reaction was identified. The low energy of activation of the reaction occurring at the phase boundary (5.1 kcal/mol) indicated that the surface reaction of radical formation cannot be rate-determining.     

An unexpected mechanism of hydrosilylation by a silyl hydride complex of molybdenum

Carbonyl hydrosilylation catalyzed by (ArN)Mo(H)(SiH(2)Ph)(PMe(3))(3) (3) is unusual in that it does not involve the expected Si-O elimination from intermediate (ArN)Mo(SiH(2)Ph)(O(i)Pr)(PMe(3))(2) (7). Instead, 7 reversibly transfers β-CH hydrogen from the alkoxide ligand to metal.     

Thermodynamic and kinetic parameters of elementary steps in gas-phase hydrolysis of SiF4. Quantum-chemical and FTIR spectroscopic studies

The energies and thermodynamic parameters of elementary steps in the proposed mechanism of silicon tetrafluoride hydrolysis in the gas phase were calculated by the ab initio quantum-chemical method (MP4//MP2/6-311G(2d,2p)) and the density functional theory (B3LYP/6-311G(2d,2p)). The proposed mechanism of gas-phase hydrolysis involves the formation of mono- and dihydroxy derivatives, hexafluorodisiloxane (SiF₃OSiF₃), and linear and cyclic siloxane polymers with the chain length from three to six Si—O and difluorosilanone units. According to the calculations, all reactions considered are endothermic and are characterized by positive Gibbs free energies. The initial hydrolysis steps can be presented with a high accuracy by two parallel processes: formation of trifluorohydroxysilane (SiF₃OH) and SiF₃OSiF₃. These are the most thermodynamically favorable among all reaction channels. The transition states of these elementary steps were found and their kinetic parameters were estimated (G = 132 and 147 kJ mol^–1, respectively). The calculation results were verified using FTIR spectroscopy of a mixture of gas-phase SiF₄ and water vapor. The comparison of the theoretical (absolute) intensities of bands in the IR spectra and integral absorption coefficients in the experimental IR spectrum made it possible to calculate the equilibrium concentrations of the reactants and equilibrium constants of elementary steps of formation of SiF₃OH and SiF₃OSiF₃, which agree with the theoretical values. The role of different derivatives in deep hydrolysis and possibilities of experimental detection of particular intermediates in the gas phase were discussed.     

2,3-dimethoxyperhydro-1,4,2,3-dioxadiazine: Synthesis,conformation, and conversion to 1-(2-hydroxyethoxy)-2-methoxydiazene-1-oxide. Crystal structure of 1-[2-(para-nitrobenzoyloxy)-ethoxy]-2-methoxydiazene-1-oxide

The oxidation of 1,2-bis(methoxyaminooxy)ethane (3) with PbO₂ afforded 2,3-dimethoxyperhydro-1,4,2,3-dioxadiazine (4) in the form of the 55:45 mixture of thetrans-4ee- andcis-4 isomers. The barrier of the ring conversion (G₂₃₈ =11.3 kcal/mole) of thecis-4 isomer was determined by the method of¹³C NMR. The regio- and stereospecific stereoelectronically controlled reaction of (4) withpara-nitrobenzoic acid gives the equimolar mixture of methylpara-nitrobenzoate and the 1,2-dialkoxydiazene oxide (5), the structure of which, and the (E)-configuration, were shown by the x-ray structural data of its acylation product — the diazene oxide (6).N. N. Semenov Institute of Chemical Physics, Russian Academy of Sciences, 117977 Moscow. Translated fromIzvestiya Akademii Nauk, Seriya Khimicheskaya, No. 11, pp. 2624–2632, November, 1992.