Homogeneous and heterogeneous radiation induced NO and SO2 removal from power plants flue gases-modeling study

The generalized mathematical model has been developed for radiation induced removal of NO and SO₂ from flue gases of power plants. This model includes energy absorption of electron beam with active species generation, reactions in gas phase, aerosol formation and growth, and liquid-phase chemistry. To investigate the role of various process parameters (initial NO and SO₂ concentrations, temperature, humidity, absorbed dose) a number of numerical calculations has been carried out. Computer modeling results are in good agreement with reported experimental data.     

Sorption of water by poly(vinyl alcohol)

The isotherms of water sorption by poly(vinyl alcohol) have been obtained by static sorption methods in a wide range of vapor activities. The properties of poly(vinyl alcohol) at various values of relative humidity have been studied by DSC, X-ray diffraction analysis, and mechanical testing. It has been shown that the correct thermodynamic analysis of sorption isotherms for sorbents with complex organization requires knowledge of their structural features. A method of allowing for the effect of osmotic pressure on the polymer sorption capacity is proposed. The pair interaction parameters estimated in this study are compared with the published data.     

Vaporization and thermodynamic properties of the PbO-V2O5 system

The vaporization of individual lead and vanadium oxides and a wide range of compositions of PbO-V₂O₅ melts has been studied. The thermodynamic characteristics of the PbO-V₂O₅ system have been determined, PbO-V₂O₅ melts show negative deviations from the ideal behavior because of the formation of thermally stable compounds in their condensed phase. For gaseous lead vanadate PbV₂O₆, the thermodynamic functions have been calculated and the standard enthalpies of formation and atomization have been determined.     

The kinetics of phase transition in systems with nonconservative order parameter

The kinetics of ordering in systems described by the nonconservative order parameter is studied near the second-order transition critical point.On leave fromDepartment of Nuclear Physics and Biophysics, Faculty of Natural Sciences, University of P. J. afárik, Moyzesova 11, 041 67 Koice, Czechoslovakia.     

Condensation of unsaturated cyclic sulfones with aldehydes

The reactivity of the 2(5) positions of dihydrothiophene dioxide has been studied. Their condensation with aldehydes leads to the formation of 2(5)-substituted derivatives containing a conjugated system of double bonds.     

Production of123I on linear electron accelerator using highly-enriched124Xe

Highly enriched xenon¹²⁴Xe /99.85%/ has been used for the experimental production of iodine¹²³I by the /,n/ reaction. As the radiation source served a 30–45 MeV electron beam produced by a linear accelerator and converted by a tungsten converter to -radiation. The yield and radionuclidic purity of¹²³I have been estimated, the content of isotopic impurities /¹²⁴I and¹²⁵I/ being for 30 MeV irradiations lower than 4×10^–3%/.     

Photochemical Degradation of Polycyclic Aromatic and Nitroaromatic Hydrocarbons in the Urban Atmosphere

Possible mechanisms of the photochemical conversion of polycyclic aromatic and nitroaromatic hydrocarbons in the urban atmosphere under the action of sunlight were analyzed. A kinetic model of the process was proposed, which takes into account the emission of harmful substances and the deposition of these substances onto the Earth's surface. It was found that emission is a predominant process within the bounds of a city. Beyond the precincts of a city, the concentrations of these hydrocarbons decrease because of photochemical degradation. In this case, the rate of this process for compounds adsorbed by soot particles is much higher than the corresponding value for compounds that occur in the gas phase. The results of calculations were compared with measurement data.     

DFT study of the effect of carbitol on the mechanism of aminolysis of 6-methyl-2-(methylsulfanyl)pyrimidin-4(3H)-one

The effect of carbitol as solvent on the mechanism of aminolysis of 6-methyl-2-(methylsulfanyl)-pyrimidin-4(3H)-one with propylamine was studied at the DFT B3LYP/6–311++G** level. The reaction in the absence of carbitol is a concerted process which may be described as one kinetic step. Carbitol forms H-complexes with propylamine, so that the reaction occurs in two kinetically distinguishable steps with a considerably lower activation barrier.     

Investigating the sensor response of ceria-containing binary metal oxide nanocomposites

The hydrogen sensing performance of ceria-containing nanocrystalline indium and tin oxides is investigated for different concentrations of added ceria. The sensor response of nanocrytsalline In₂O₃ is considerably enhanced at low CeO₂ concentrations. In contrast, low levels of CeO₂ cause a substantial drop in the sensor response of SnO₂-based composite; at a 3 wt % level of added ceria, its hydrogen sensing ability is almost entirely suppressed. Possible causes of these effects are investigated via X-ray photoelectron spectroscopy (XPS) and X-ray diffraction. XPS data show that additions of CeO₂ have different effects on the structure of the base oxides (In₂O₃ and SnO₂), with implications for the hydrogen sensing performance of the composites.