Sulfur and nitrogen oxide conversion in air by microsecond electron beams

Sulfur and nitrogen oxide conversion in an ionized gaseous mixture modeling the composition of flue gases from thermal power plants is studied experimentally. A pulsed microsecond beam of electrons is used as an ionization source. Oxides of both elements are shown to influence the conversion process. Possible kinetic mechanisms for removing the oxides from the gaseous mixture are discussed.     

Numerical method for solving an inverse problem for a population model

The inverse problem of determining the growth rate coefficient of biological objects from additional information on their time-dependent density is considered. Two nonlinear integral equations are derived for the unknown coefficient, which is determined on part of its domain from one equation and on the remaining part from the other equation. The nonlinear integral equations are solved by iterative methods. The convergence conditions for the iterative methods are formulated, and results of numerical experiments are presented.     

NUMERICAL SIMULATION OF OPEN WAVEGUIDE CONVERTERS USING FDTD METHOD

We study 3-dimensional asymmetric diffraction problems for waveguide-based electro-dynamic systems, radiating to infinite free space. For calculations we utilize the FDTD (Finite Difference Time Domain) numerical simulation method with the UPML (Unsplit Perfectly Matched Layer) absorbing boundary conditions. This paper states that the FDTD method, in spite of its relatively low calculation speed, has an approved ability of solving certain problems that cannot be solved by the other traditional numerical simulation methods (the method of integral equation, the method of scattering matrix).     

Minimization of Diffraction Losses in Big Gaps of Multi-Mode Waveguides

A systematic approach to design of low-loss miter bends and quasi-optical gaps in multi-mode waveguides is proposed. Several examples illustrate the approach. A mode filter based on a quasi-optical gap in the 31.75 mm diameter corrugated waveguide at frequency 84 GHz has been tested in low (mW) and high-power (200 kW, CW) experiments.     

Dissociation energies of O–H bonds in 3-pyridinols

The O?H bond dissociation energy (D _O?H) has been estimated for 20 substituted 3-pyridinols and a substituted 3-pyrimidinol from experimental kinetic data by the intersecting parabolas method using α-tocopherol and 4-methoxyphenol as reference compounds. The following D _O?H values (kJ/mol) have been obtained: 363.7 for 3-pyridinol, 365.3 for 2-alkyl-3-pyridinols (five compounds), 358.8 for 2-alkyl-6-methyl-3-pyridinols (six compounds), 378.1 for 5-benzyl-3-pyridinol, 353.2 for 2,4,6-trimethyl-3-pyridinol, 340.9 for 2-benzyl-6-methoxy-3-pyridinol, 345.8 for 2,6-dimethoxy-5-benzyl-3-pyridinol, 381.7 for 2-ethyl-4-nitro-6-methyl-3-pyridinol, 376.8 for 2-isopropyl-4-nitro-6-methyl-3-pyridinol, 318.3 for 2,4-dimethyl-6-dimethylamino-3-pyridinol, 357.3 for mexidol, and 322.2 for 2,4-dimethyl-6-dimethylamino-3-pyrimidinol. The substituent effect on the O?H bond dissociation energy in 3-pyridinols is considered. The stabilization energies of pyridinoxyl and phenoxyl radicals are compared. The activation energies and rate constants have been calculated for a series of reactions of various radicals with 3-pyridinols.     

Parabolic model of the concerted molecular decomposition of chloroalkanes

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.