Vol 10, No 3 (2016)

The LCAO MO self-consistent field method in combination with the 6-31** basis set is used to calculate sections of the potential energy surface for a proton in the NH₃…HCl system in the presence of an external electrostatic field. The field strength is varied in the range of 0.000 to 0.017 a. u. In the absence of the field, the potential of the proton in the isolated complex has one well, the N–Cl distance is equal to 2.92 Å, and the NH₃…H–Cl bond is a hydrogen bond. With increasing distance between the N and Cl atoms, a second well appears in the potential, with the well near the Cl atom remaining deeper. In the presence of an external electric field, with increasing its strength, the depth of the well near the N atom increases, while the height of the barrier for proton transfer from the chlorine to the nitrogen atom decreases. At a certain field strength, the well near the nitrogen atom becomes deeper than that near the chlorine atom, so the proton moves to the nitrogen, making the complex ionic. Thus, the external electric field can influence the type of chemical bond in NH₃…HCl system.

The exact solution for a polaron in a lattice with cubic nonlinearity is obtained. The electron–phonon interaction is taken into account in the Su–Schrieffer–Heeger approximation. The system of nonlinear differential equations in partial derivatives, obtained in the continuum approximation, is exactly integrable at a certain ratio between the parameters of nonlinearity, α, and the electron–phonon interaction, χ. An approximate solution is obtained for arbitrary values of α and χ. A good agreement between the analytical results with the numerical simulation is observed at not too large values of parameters α and χ, where the continuum approximation is valid. Stable solutions also exist at higher values of these parameters.

The shape of NMR absorption line for typical ionic crystals, molecular crystals, and glasses is studied. The proposed theory and available experimental results suggest that the shape of NMR spectra of conventional dielectric crystals (and even molecular) is the convolution of a frequency-truncated nearly-rectangle-shaped function (characteristic oscillations in free precession signals) and a Gaussian-like function. A Gaussian-like shape of the spectra of glasses with a rigid structure (no oscillations in the free precession signal) is probably associated with a random scatter of interatomic distances. The results are interpreted within the framework of the proposed theory. It is demonstrated that, at least for solids the lattice of which contains no isolated groups of nuclei and are not quasi-one-dimensional, the structure only weakly affects the shape of the spectrum, which in turn is associated with the onset of dynamic chaos in the spin system.

The intersecting parabolas model (IPM) is used to analyze the measured kinetic parameters for the concerted molecular decomposition of chloroalkanes RCl to olefin and HCl. According to this model, the configuration of the transition state is formed by three atoms: C…H…Cl. The activation energy E and the rate constant k for 12 previously unstudied reactions of concerted molecular decomposition of RCl are calculated based on the enthalpy of reaction by using the IPM algorithms. The factors that influence the activation energy E for RCl decomposition are established: the enthalpy of reaction, energy of stabilization of radical R^•, presence of a π bond adjacent to the reaction center, and dipole–dipole interaction for the decomposition of polychloroalkanes. The values of E and k for reverse reactions of addition of HCl to olefins are evaluated. The energy spectrum of partial activation energies for the concerted molecular decomposition of RCl is constructed.

The enthalpy change of disproportionation reaction of nitroxyl and peroxyl radicals was calculated by the DFT B3LYP/cc-pVDZ method. The regeneration of the corresponding hydroxylamine during the oxidation of unsaturated compounds inhibited by nitroxyl radicals is shown to be associated with the disproportionation of the nitroxyl and peroxyl radicals.

Density Functional Theory (DFT) was utilized to study the hydrolysis mechanism and kinetic analysis of carbonyl sulfide (COS). The structures of reactants (R), transition states (TS), intermediates (IM) and products (P) were analyzed and a conclusion reached that hydrolysis mechanism of COS occurs in two paths with One path as a C=S path and the other as a C=O path and all featuring potential for forming H₂S and CO₂. Function change analysis of COS hydrolysis indicated the rate-determining step of COS hydrolysis was the first elementary reaction as OH and H in H₂O attacked C=O and S=O in COS, respectively, with the two paths parallel and competitive and the C=S path more reactionary than the C=O path. Influence on each elementary reaction was also not consistent with reaction temperature increase. The study also included further investigation of the COS catalytic hydrolysis.

The ignition delay times of heptane–air and diesel oil–air mixtures with and without additives of mechanoactivated Mg–MoO³, Al–MoO³, and Mg–fluoroplastic nanopowders are measured using a rapid-mixture-injection setup. At temperatures below a certain threshold value, the metal–MoO³ additives produce practically no effect on the ignition delay time, whereas at higher temperatures, these additives sharply reduce the ignition delay time, down to the resolution time of the experimental method. The promoting efficiency of the small heterogeneous additives tested is many times superior to that of the known homogeneous promoters. Magnesium–fluoroplastic additives are demonstrated to produce no promoting effect on the ignition of the fuel–air mixtures studied. The mechanism of the action of the heterogeneous additives on the gasphase self-ignition of fuels is discussed.

This article presents a further analysis of isotopic labeling data on the mechanism of the detonation of TNT-, RDX-, and HMX-containing mixtures and on the release of free carbon from these mixtures. The distribution of carbon isotopes among the condensed explosion products and, for the first time, among the gaseous ones is considered in relation to the particle size of the mixed explosives. A sequence of main chemical reactions in the detonation wave is suggested to account for the experimental data discussed.

Multi-variant three-dimensional numerical simulations demonstrate the feasibility of the continuous- detonation process in an annular combustor of a ramjet power plant operating on hydrogen as fuel and air as oxidant in conditions of flight at a Mach number of M₀ = 5.0 and an altitude of 20 km. Conceptual schemes of an axisymmetric power plant, 400 mm in external diameter and 1.3 to 1.5 m in length, with a supersonic intake, divergent annular combustor, and outlet nozzle with a frusto-conical central body are proposed. Calculations of the characteristics of the internal and external flows, with consideration given to the finite rate of turbulent-molecular mixing of the fuel mixture components with each other and with the combustion products, as well as the finite rate of chemical reactions and the viscous interaction of the flow with the bounding surfaces, have shown that, in these flight conditions, the engine of such a power plant has the following performance characteristics: the thrust, 10.7 kN; specific thrust, 0.89 (kN s)/kg; specific impulse, 1210 s; and specific fuel⋅consumption 0.303 kg/(N h). In this case, the combustor can operate with one detonation wave traveling in the annular channel at an average velocity of 1695 m/s, which corresponds to a detonation wave rotation frequency of 1350 Hz. It is shown that, an operating combustor has regions with subsonic flow of detonation products, but the flow is supersonic throughout its outlet section.

The interaction of hydrogen molecules with the surface of the particles of a finely disperse dielectric CsNO₃, KMnO₄, or Pb(NO₃)₂ was found to be accompanied by the emergence of an electric field in the powder layer. This effect is independent of the material of the identical metal electrodes (Pt, Au, Hf, Mo, Pb, Al) and is determined by the decay into hydrogen Н⁺ ions and the electrons of the chemisorbed Н₂ molecules.

The effect of mechanical pretreatment of surplus activated sludge from the wastewater treatment facilities of a plant producing chips (LLC “Frito Lay Manufacturing,” Kashira, Moscow oblast) in a cavitation disintegrator on methane generation in the process of anaerobic conversion is investigated. In laboratory conditions, cavitation disintegration pretreatment of the activated sludge results in a two- to sixfold increase in the transfer of various types of organic materials from the cell suspension into the aqueous phase. It is demonstrated that cavitation pretreatment of the activated sludge makes it possible to produce 31% extra methane as compared to the amount produced from the original sludge.

Plasma protein in blood play an important role in transportation of drug. So it is important to know the binding of drug with plasma protein. In this study we successfully observed the interaction of 2-benzamido-4-methylpentanoic acid-2-cyclohexyl carboxamide ligand (2-bmca) with Bovine serum albumin (BSA) using gel exclusion chromatographic technique at different pH. Absorbance value for collected fraction was measured on UV-vis Spectrophotometer. Differences in the absorbance value of collected fraction give the specific binding of interacting species with BSA. Interacting study shows that ligand (L) bounds to the BSA more significantly at pH 3 than at pH 4 and 5, which shows binding is more at acidic pH. Scatchard analysis gives the association constants (K_f) and the saturation value (n) for ligand(L) with BSA. Molecular modeling study gives the efficient energy value–231.16 which confirms the binding of ligand (L) with BSA.

The industrial synthesis of pigments and dyes generates hazardous chemicals. These chemicals are released into water, soil and environment and regarded as a major source of environmental pollution. H acid is also an important dye intermediate. In this study, the focus was on the bacterial degradation of H acid (1-amino-8-naphthol-3,6-disulfonic acid) of different concentrations and its degradation estimation method. The biodegradation was identified by the help of IR, UV-Visible spectrophotometer and high performance liquid chromatography (HPLC). A method was developed for the estimation of percent biodegradation of H acid with the help of HPLC. The developed method was applicable on standard as well as biodegraded products and on other compounds with the sulfonic acid group. It was found that H acid of concentration 300 ppm and below can be completely degraded with Bacillus subtilis. However, over 300 ppm, the bacterial degradation did not work efficiently.

The mechanical property of cellulose is universally considered as an important parameter, which reflects the service life of cellulosic insulation paper in the transformer. In this work, the mechanical property of hydrous amorphous cellulose has been studied using molecular dynamics. Analysis of the mechanical parameters of amorphous cellulose cells reveals that amorphous cellulose remains isotropic either in the hydrous or in the anhydrous state, but shows a weakening trend in mechanical property with the increase of water content. Both intramolecular and intermolecular hydrogen bonds in cellulose molecules decrease with increasing water content, directly leading to the decline of cellulose cohesive energy density, solubility parameters, and mechanical parameters. High water content in amorphous cellulose gives bigger interchain distance of cellulose molecules, indicating that the intermolecular interaction of cellulose molecules is weakened greatly by water.

The formation of nanodroplets in solutions of gelating trifluoroacetylated amino alcohols (TFAAA), constituting one of the fractions of the dispersed phase, is simulated by the molecular dynamics method. It is shown that the main contribution to the energy of formation of nanodroplets comes from dispersion forces (~14 kJ/mol), which constitutes 3/4 of the total energy of interaction of a pair of molecules. The dipole–dipole component of the interaction energy for the molecules with anticollinear dipole moments is ~kT. It is shown that there are differences in the topology of pairs of bound homochiral TFAAA molecules, associated with their nonhomeomorphicity. In the first case, the chiral tetrahedrons of the molecules are nested into each other. During condensation, due to the formation of stacks, such pairs are capable of anisotropic growth. In the second case, the tetrahedrons join via their bases, creating isometric nuclei for isotropic condensation.

In₂O₃ + CeO₂ and In₂O₃ + ZnO nanocomposites are prepared by the mixing of commercial nanopowders of respective oxides or the impregnation of indium oxide nanoparticles with cerium or zinc salts and the subsequent transformation of the salts into respective oxides. According to X-ray diffraction analysis, regardless of the preparation method, only two phases—indium oxide and cerium or zinc oxide—are present in the samples. The sizes and structure of the nanoparticles in the nanocomposites are determined by transmission electron microscopy and X-ray diffraction analysis. It is found that the use of the impregnation method leads to the formation of small clusters of cerium or zinc oxides on the surface of the indium oxide nanoparticles. The size of the cerium and zinc oxide nanoparticles in the impregnated samples is 3–15 and 5–25 nm, respectively. The size of nanoparticles of these oxides in the impregnated samples slightly decreases with an increase in their content in the composite.

The migration of an impurity atom over a honeycomb-type hexagonal lattice on a solid surface initiated by the diffusion of vacancies is theoretically studied. The case of small surface coverages of vacancies and impurity atoms is examined. The time dependence of the mean-square displacement at long time is demonstrated to be not very different from linear, whereas the spatial density distribution is close to a Gaussian profile, a result that makes it possible to introduce a diffusion coefficient. For the latter, an analytical expression is obtained, which differs from the product of the diffusion coefficient of vacancies and their relative concentration V_v only by a numerical factor. The dependence of the diffusion coefficient of the impurity atom on the ratio p of the frequency of its jumps to the frequency of jumps of vacancies is analyzed. In the kinetic mode, when the frequency of jumps of the impurity atom is small, the diffusion coefficient of the impurity is a linear function of p, while in the opposite case, a saturation takes place, making this coefficient independent of the frequency of jumps of the impurity atom.