Search

Abstract: Global warming is the major environmental issue caused by greenhouse gases, especially C[O.sub.2]. This demands urgent action to reduce or offset C[O.sub.2] emission from power plants, which could be [...]

In the present work, a numerical analysis has been presented to show the variations in flame structure, flame radiation, and formations of soot and NO in methane-air laminar nonpremixed flames with different C[O.sub.2] dilutions of fuel. It is observed that the flame length reduces as the dilution of the fuel stream by C[O.sub.2] increases while maintaining constant fuel jet velocity at the burner tip. However, the flame length remains almost unchanged with different blends of C[H.sub.4] and C[O.sub.2] if the burner loading (i.e., fuel flow rate x Cheating value of fuel) is kept constant. Both soot and NO formations decrease monotonically when the C[O.sub.2] fraction in the fuel is increased. The radiation from the flame also decreases when C[O.sub.2] dilution of the fuel is increased, particularly, when the fuel jet velocity is maintained constant. [DOI: 10.1115/1.4001809] Keywords: nonpremixed flame, flame structure, C[O.sub.2] dilution, soot, NO

Soot particles produced by incomplete combustion processes are one of the major components of urban air pollution. Chemistry at their surfaces lead to the heterogeneous conversion of several key trace gases; for example N[O.sub.2] interacts with soot and is converted into HONO, which rapidly photodissociates to form OH in the troposphere. In the dark, soot surfaces are rapidly deactivated under atmospheric conditions, leading to the current understanding that soot chemistry affects tropospheric chemical composition only in a minor way. We demonstrate here that the conversion of N[O.sub.2] to HONO on soot particles is drastically enhanced in the presence of artificial solar radiation, and leads to persistent reactivity over long periods. Soot photochemistry may therefore be a key player in urban air pollution. HONO | nitrogen oxides | photochemistry | aerosol | heterogeneous chemistry doi/ 10.1073/pnas.0908341107

A mean-field theory study is made of the behaviour of a kinetic model of the reduction reaction of NO by CO catalyzed by a surface with simple heterogeneity consisting of two interconnected sectors that differ in their NO dissociation activation energy. A synergistic effect is manifested in the activity, apparent activation energy, and reaction order of the system. This situation, analogous to that observed in the literature in the case of a heterogeneous catalytic particle, is used in the paper to analyze a real case of a bimetallic catalyst. Key words: mean-field model in superficial reaction, catalytic CO-NO reaction, surface heterogeneity in superficial reaction, superficial catalytic reaction, CO-NO reaction over palladium, steps-terraces superficial heterogeneity On a effectue une etude, a base de la theorie du champ moyen, du comportement d'un modele cinetique de la reaction de reduction du NO par le CO, catalysee par une surface comportant une simple heterogeneite formee de deux secteurs interrelies qui different par leur energie d'activation de dissociation du NO. A part d'autres aspects, un effet synergique se manifeste dans l'activite du systeme, l'energie d'activation apparente et l'ordre de la reaction. Cette situation, analogue a celle observee dans la litterature dans le cas d'une particule catalytique heterogene, est utilisee dans ce travail pour analyser un cas reel de catalyseur bimetallique. Mots-cles: modele du champ moyen dans l'etude d'une reaction superficielle, reaction catalytique CO-NO, heterogeneite en surface dans une reaction superficielle, reaction catalytique superficielle, reaction CO-NO sur du palladium, heterogeneite superficielle en paliers et en terrasses, Introduction Over the last decades, great progress has been made in the knowledge of catalytic surface reactions, owing on the one hand to modern laboratory techniques and on the other [...]

The use of stable isotope labeled substrates and subsequent analysis of urinary nitrate, forms a noninvasive test for evaluation of the in vivo NO metabolism. The present paper describes a new method for simultaneous quantification of [sup.15]N-nitrate and total nitrate with gas chromatography combustion isotope ratio mass spectrometry (GC-C-IRMS). Nitrate, isolated from urine with a nitrate selective resin, was reduced to nitrite using copperized cadmium. Subsequently, Sudan I was formed by diazotation. Sudan II was added as internal standard, and both molecules were analyzed with GC-C-IRMS as tert-butyldimethylsilyl derivatives. The accuracy was determined during a recovery study of two different known nitrate concentrations and two [sup.15]N-enrichments. A recovery of 101.6% and 103.9% for total nitrate and 107.6% and 91.2% for [sup.15]N-nitrate was obtained, respectively. The validated method was applied on complete 72 h urine collections after intravenous administration of [sup.15]N-nitrate and [sup.15]N-arginine in humans. On average, 51.8% (47.0-71.0%) of administered [sup.15]N-nitrate was excreted, while 0.68% (0.44-1.17%) of [sup.15]N-arginine was metabolized to nitrate. In conclusion, this method can be used for accurate simultaneous determination of [sup.15]N-nitrate and total nitrate concentrations in urine and can be applied in clinical studies for noninvasive evaluation of NO metabolism in vivo. 10.1021/ac9019208

Gaseous HCl generated from a variety of sources is ubiquitous in both outdoor and indoor air. Oxides of nitrogen (N[O.sub.y]) are also globally distributed, because NO formed in combustion processes is oxidized to N[O.sub.2], HN[O.sub.3], [N.sub.2][O.sub.5] and a variety of other nitrogen oxides during transport. Deposition of HCl and N[O.sub.y] onto surfaces is commonly regarded as providing permanent removal mechanisms. However, we show here a new surface-mediated coupling of nitrogen oxide and halogen activation cycles in which uptake of gaseous N[O.sub.2] or [N.sub.2][O.sub.5] on solid substrates generates adsorbed intermediates that react with HCl to generate gaseous nitrosyl chloride (CINO) and nitryl chloride (CIN[O.sub.2]), respectively. These are potentially harmful gases that photolyze to form highly reactive chlorine atoms. The reactions are shown both experimentally and theoretically to be enhanced by water, a surprising result given the availability of competing hydrolysis reaction pathways. Airshed modeling incorporating HCl generated from sea salt shows that in coastal urban regions, this heterogeneous chemistry increases surface-level ozone, a criteria air pollutant, greenhouse gas and source of atmospheric oxidants. In addition, it may contribute to recently measured high levels of CIN[O.sub.2] in the polluted coastal marine boundary layer. This work also suggests the potential for chlorine atom chemistry to occur indoors where significant concentrations of oxides of nitrogen and HCl coexist. heterogeneous chemistry | lower atmosphere

The influence of incomplete liquid fuel prevaporization on the emissions of nitric oxides in a swirl stabilized model gas turbine combustor is investigated experimentally and numerically. The design of the model combustor enables the variation of the degree of prevaporization. This is achieved by using two liquid fuel injectors. One injector is located far upstream of the combustor and generates a fully prevaporized and premixed air fuel mixture. The second injector is located at the combustor inlet. Consequently, the liquid fuel mass flow split between the two injectors determines the fraction of nonprevaporized fuel present in the reaction zone. The NO/N[O.sub.2] measurements were performed with a chemoluminescence analyzer. In accordance to the findings of other researchers, the present experimental study revealed that the influence of prevaporization on nitric oxide emissions is of significance for practical applications. The experimental studies were accompanied by numerical studies of partially prevaporized lean combustion in an abstracted configuration. The purpose of this numerical study is to gain a detailed understanding of the influence of droplet slip on droplet flame position and peak temperature. The droplet slip velocity was found to have a significant impact on the peak temperature of the droplet flame and, therefore, NO formation rates within the droplet flame. The combustion system used for the experimental investigation was characterized regarding droplet slip velocities with an extended laser Doppler anemometry technique. The comparison between numerical and experimental results shows that the droplet slip velocities in the macroscopic reaction zone are within the transition range from an envelope to a wake flame. It is concluded that small-scale mixing effects play a significant role in the formation of nitric oxides in spray combustion systems with incomplete prevaporization. [DOI: 10.1115/1.2906185]

Fuels produced from renewable sources offer an economically viable pathway to curtail emissions of greenhouse gases. Two such liquid fuels in common usage are biodiesel and ethanol derived from soybean, corn, or other food crops. In recent years, significant effort has been devoted to identify alternate feedstock sources and conversion techniques to diversify the biofuels porfolio. In this study, we have measured emissions from fames of diesel, biodiesel, emulsified bio-oil, and diesel-biodiesel blends. Experiments are conducted in an atmospheric pressure burner with an air-atomized injector and swirling primary air around it to replicate typical features of a gas turbine combustor. Experiments were conducted for fixed air and fuel flow rates, while the airflow split between the injector and the coflow swirler was varied. Results show a significant reduction in emissions as the fraction of total air fed into the atomizer is increased. Blue flames, reminiscent of premixed combustion, and low emissions of nitric oxides and carbon 1monoxide were observed for all fuel blends. In general, the emissions from biofuel flames were comparable or lower than those from diesel flames. [DOI: 10.1115/1.2836747]

In this paper, the development of an eight-step global chemical kinetic mechanism for methane oxidation with nitric oxide formation in lean-premixed combustion at elevated pressures is described and applied. In particular, the mechanism has been developed for use in computational fluid dynamics and chemical reactor network simulations of combustion in lean-premixed gas turbine engines. Special attention is focused on the ability of the mechanism to predict N[O.sub.x] and CO exhaust emissions. Applications of the eight-step mechanism are reported in the paper, all for high-pressure, lean-premixed, methane-air (or natural gas-air) combustion. The eight steps of the mechanism are as follows: (1) oxidation of the methane fuel to CO and [H.sub.2]O, (2) oxidation of the CO to C[O.sub.2], (3) dissociation of the C[O.sub.2] to CO, (4)flame-NO formation by the Zeldovich and nitrous oxide mechanisms, (5) flame-NO formation by the prompt and NNH mechanisms, (6) postflame-NO formation by equilibrium H-atom attack on equilibrium [N.sub.2]O, (7) postflame-NO formation by equilibrium O-atom attack on equilibrium [N.sub.2]O, and (8) post-flame Zeldovich NO formation by equilibrium O-atom attack on [N.sub.2]. [DOI: 10.1115/1.2795787]

The electronic structure, hybrid quantum mechanical-molecular mechanical and classical molecular dynamics simulations are used for examining the eggression pathway followed by the nitrate anion. The results have shown that the nitrate anion is released through a distinct eggression pathway, which is not delineated in the X-ray crystallographic structure of the oxygenated form of truncated hemoglobin N.

The crystal structure and spectroscopic characteristics of the mononuclear copper(I)-nitrosyl complexes [Cu(L3)(NO)] and [Cu(L3E)(NO)](Cl[O.sub.4]) with the related coligands [L3.sup.-] (hydrotris(3-tert-butyl-5-isopropyl-1-pyrazolyl)borate) and L3E (tris(3-tert-butyl-5-isopropyl-1-pyrazolyl)methane) are described. The characterization of end-on bound NO to copper(I) has determined the binding mode of the Cu-NO intermediate of Cu nitrite reductase in solution.

FLOX[R], or flameless combustion is characterized by ultralow N[O.sub.x] emissions. Therefore the potential for its implementation in gas turbine combustors is investigated in recent research activities. The major concern of the present paper is the numerical simulation of flow and combustion in a FLOX[R]-combustor [Wunning, J. A., and Wunning, J. G., 1997, 'Progress in Energy and Combustion Science,' 23, pp. 81-94; Patent EP 0463218] at high pressure operating conditions with emphasis on the pollutant formation. FLOX[R]-combustion is a highly turbulent and high-velocity combustion process, which is strongly dominated by turbulent mixing and chemical nonequilibrium effects. By this means the thermal nitric oxide formation is reduced to a minimum, because even in the nonpremixed case the maximum combustion temperature does not or rather slightly exceeds the adiabatic flame temperature of the global mixture due to almost perfectly mixed reactants prior to combustion. In a turbulent flow, the key aspects of a combustion model are twofold: (i) chemistry and (ii) turbulence/chemistry interaction. In the FLOX[R]-combustion we find that both physical mechanisms are of equal importance. Throughout our simulations we use the complex finite rate chemistry scheme GRI3.0 for methane and a simple partially stirred reactor (PaSR) model to account for the turbulence effect on the combustion. The computational results agree well with experimental data obtained in DLR test facilities. For a pressure level of 20 bar, a burner load of 417 kW and an air to fuel ratio of [lambda] = 2.16 computational results are presented and compared with experimental data. Keywords: FLOX[R]-combustion, numerical simulation, complex finite rate chemistry, PaSR model [DOI: 10.1115/1.2747266]

The purpose of this work is to evaluate a new polypropylene (PP)-based nitroxyl radical generator (NOR) and offer comparisons with a commonly used peroxide in the production of controlled-rheology polypropylene (CRPP) resins. CRPP resins are produced by reactive processing in a batch mixer by using different amounts of either the NOR or a peroxide initiator at different temperatures. Molecular weight and rheological properties are determined for all CRPP produced and a comparison between the effectiveness of the NOR and the peroxide initiator is provided. POLYM. ENG. SCI., 47:2118-2123, 2007. © 2007 Society of Plastics Engineers, INTRODUCTION Polypropylene (PP) is one of the most commonly used materials in the plastics industry. PP resins are being produced for a very broad range of end use applications. For [...]

Two novel lanthanide cluster compounds are synthesized by incorporating N[O.sub.3.sup.-] ligands with trigonal planar geometry planted into the cluster core backbone through coordination bonds. These two compounds have represented the first tetramers that are based on the linkage of two different types of high-nuclearity lanthanide clusters and isonicotinate (IN) ligands and the {[D.sub.26]} clusters and IN linkers.

Various molecular dynamics simulations are used to describe the structural and energetic properties of the solutions containing water, urea, as well as trimethylamine-N-oxide (TMAO), where TMAO acts to counter the protein denaturing effect of urea. The results of the analysis show that the TMAO counter denaturation occurs only because water and urea prefer to solvate TMAO than the protein, which also inhibits it's folding in the long run.

In order to improve the thermal efficiency of the oxygen-blown integrated gasification combined cycle (IGCC) and to meet stricter environmental restrictions among costeffective options, a hot/dry synthetic gas cleanup is one of the most hopeful choices. The flame temperature of medium-Btu gasified fuel used in this system is high so that N[O.sub.x] formation by nitrogen fixation results to increase significantly. Additionally, the gasified fuel contains nitrogenous compound, as ammonia, and it produces nitrogen oxides, the fuel N[O.sub.x], in the case of employing the hot/dry gas cleanup. Low N[O.sub.x] combustion technology to reduce both fuel-N[O.sub.x] and thermal-N[O.sub.x] emissions has been required to protect the environment and ensure low cost operations for all kinds of oxygen-blown IGCC. In this paper, we have demonstrated the effectiveness of two-stage combustion and nitrogen injection techniques, and also showed engineering guidelines for the low-N[O.sub.x] combustor design of oxygen-blown gasified, medium-Btu fuels. The main results obtained are as follows: (1) Based on the basic combustion tests using a small diffusion burner, we clarified that the equivalence ratio at the primary combustion zone has to be adjusted according to the fuel conditions, such as methane concentration, CO/[H.sub.2] molar ratio, and calorific values of gasified fuels in the case of the two-stage combustion method for reducing fuel-N[O.sub.x] emissions. (2) From the combustion tests of the medium-Btu fueled combustor, two-stage combustion with nitrogen direct injection into the combustor results in reductions of N[O.sub.x] emissions to 34 ppm (corrected at 16% [O.sub.2]) or less under the gas turbine operational conditions of 25% load or higher for IGCC in the case where the gasified fuel contains 0.1% methane and 500 ppm of ammonia. Through nitrogen direct injection, the thermal efficiency of the plant improved by approximately 0.3% (absolute), compared with the case where nitrogen was premixed with gasified fuel. The CO emission concentration decreased drastically, as low as 20 ppm, or combustion efficiency was kept higher than 99.9%. The above results have shown that a two-stage combustion method with nitrogen direct injection is very effective for reducing both fuel-N[O.sub.x] and thermalN[O.sub.x] emissions at once in IGCC, and it shows the bright prospects for low N[O.sub.x] and stable combustion technology of medium-Btu fuel. [DOI: 10.1115/1.2432896] Keywords: gas turbine, combustor, gasification, medium calorific fuel, ammonia, fuel-N[O.sub.x] emissions, thermal-N[O.sub.x] emissions, low-N[O.sub.x] combustion, two-stage combustion, nitrogen direct injection

A detailed laboratory study on the removal of oxides of nitrogen ([NO.sub.x]) from the exhaust of a stationary diesel engine was carried out using pulsed electrical discharge promoted adsorbent/catalytic processes. In this study, the filtered exhaust from the diesel engine is made to pass through a combination of plasma reactor and adsorbent/ catalytic reactor connected in series. This combination is referred to as cascaded process. In the cascaded plasma-adsorbent process, the plasma treating filtered exhaust was cascaded with adsorbents (MS-13X/ Activated alumina/Activated charcoal). The cascaded plasmaadsorbent process exhibits a superior [NO.sub.x] removal characteristic compared to the individual processes-plasma or adsorbent processes. In the cascaded plasma-catalyst process, the plasma treating filtered exhaust was cascaded with activated alumina catalyst. For the purpose of investigation, both two-stage and four-stage cascaded plasma-activated alumina catalyst processes were separately studied. The synergy effect and limitation of two-stage process and improved performance of four-stage process are explained. Further, experiments were conducted at room temperature as well as at higher temperatures. Index Terms--NOx removal, non-thermal plasma, engine exhaust cleaning, electrical discharge application, air pollution.

The reactions of several nitrogen oxides with iron porphyrin models for heme/[N.sub.x][O.sub.x] systems are studied. FTIR and optical spectroscopy show that reaction of small increments of N[O.sub.2] with sublimed thin layers of the [Fe.sup.II] complex Fe(Por) leads to formation of the five-coordinate nitrito complexes Fe(Por)([eta.sup.1]-ONO).

Azobenzene derivatives carrying a nitroxide radical (aminoxyl) were prepared and their photoisomerization reaction to the corresponding cis-isomers was investigated. The unsubstituted derivatives at the para position were found to undergo photoisomerizations by irrdiation and the intermolecular magnetic interactions were observed by structural change for each photochromic couple.

The interaction of N[O.sub.3] free radical and [N.sub.2][O.sub.5] with decane flame soot is examined in a Knudsen flow reactor at ambient temperature. The inverse concentration dependence of [gamma] below the concentration threshold has revealed a complex reaction mechanism for both N[O.sub.3] and [N.sub.2][O.sub.5].

Interaction with ozone transfers its anomalous (non-mass-dependent) [sup.17]O enrichment to atmospheric nitrogen oxides and nitrate. The [sup.17]O anomaly ([DELTA][sup.17]O) in nitrate can be used to identify atmospheric nitrate inputs into terrestrial and aquatic environments as well as to study the role of ozone in the atmosphere's reactive nitrogen cycle. We report here on an online method for analysis of the [sup.17]O anomaly, using a strain of denitrifiers to convert nitrate to [N.sub.2]O, which decomposes quantitatively to [N.sub.2] and [O.sub.2] in a gold furnace at 800 [degrees]C, followed by gas chromatographic separation and isotope analysis of [O.sub.2]. This method requires ~50 nmol of nitrate, 2-3 orders of magnitude less than previous offline thermal decomposition methods to achieve a similar analytical precision of 0.5[per thousand] for [DELTA][sup.17]O. There is no significant memory effect, but calibration via nitrate or N20 reference materials is required for scale normalization. The [N.sub.2]O decomposition method is shown to be well-suited for nitrate analysis in freshwater and seawater samples from various environments.

Dynamic Monte Carlo simulations are used to investigate the kinetics of the catalytic reduction of NO on Rh(111) surfaces. The reaction scheme where the production of [N.sub.2] is assumed to result mainly from a pathway involving the formation of a [(N-NO).sup.*] intermediate is supported by the study and defines a reliable model capable for predicting the changes in reaction rate as a function of temperature and NO:CO gas composition.

The first partially oxidized [[Pt(ox)2].sup.n-] complex with a paramagnetic [Cu.sup.II]-bipyridine complex linking to the conducting chain is reported. Magnetoresistance measurements at ambient pressure indicate no interactions of the conduction electrons in the Pt chain with the local spins on [Cu.sup.II] ions and the resistivity decreased with application of hydrostatic pressures of up to 3 GPa.

The infrared (IR) spectra of [H.sub.2]O + NO, HDO + NO, and [D.sub.2]O + NO, isolated in solid neon at low temperature is investigated by neon matrix-isolation method combined with IR absorption spectroscopy. The structure of the second observed 1:1 [H.sub.2]O-NO complex has resulted from columbic attractions between water and nitric oxide and it could be stabilized only in matrix, probably by interaction between NO, water and [(Ne).sub.n].

The adsorption structure of NO on reconstructed Pt(110)-(1 x 2) surface is studied with X-ray photoelectron spectroscopy (XPS), X-ray photoelectron diffraction (XPD), low-energy scanned-angle photoelectron diffraction (LESA-PD), and near-edge X-ray absorption fine structure (NEXAFS) spectroscopy. The model is supported by the N K-edge NEXAFS experiments and is consistent with the reported model based on the density functional theory.

The reactive uptake of gaseous compounds by organic-coated aqueous aerosols is theoretically analyzed and applied to the heterogeneous hydrolysis of N2O5. It was shown that theses processes have a negligible influence if the coating is relatively thin and gas/organic partitioning coefficient as well as the diffusion coefficient of the reactant in the organic phase have similar magnitude with the corresponding parameters for the aqueous phase.

A study of the mechanisms of the reaction of H2XN (X = C, Si) is conducted with NO at the level CCSD(T)/aug-cc-PVTZ/B3LYP/6-31++G(d,p). The results indicate that there are two favorable reaction pathways in the reaction H2CN + NO that have similar energy barriers.

Rotationally inelastic scattering of rare gas atoms and oriented NO molecules exhibiting a remarkable alternation in the sign of steric asymmetry between even and odd changes in rotational quantum number are presented. It is observed that the effects are found in full quantum-mechanical scattering calculations.d

Electron paramagnetic resonance study of the surface basicity of calcium oxide was carried out. CaO forms ozonide ions upon [O.sub2.] adsorption and N[O.sub.3][.sup.2-] anions under low pressures of NO indicating presence of defects like positive holes dispersed in the bulk and originated by the unavoidable presence of [Na.sup.} ions in the composition of the solid.

Transient response and temperature-programmed desorption/reaction (TPD/TPR) methods are used to analyze the formation of adsorbed N[O.sub.x] from [N.sub.2]O and its influence during [N.sub.2]O decomposition to [O.sub.2] and [N.sub.2] over FeZSM-5 catalysts at temperatures below 653 K. The reactivity of the loaded oxygen with respect to CO oxidation is compared in the presence and without surface N[O.sub.(x,ads)] species.

An investigation is conducted of the kinetics of reactive uptake of [[N.sub.2][O.sub.5]] on submicron aerosol particles containing humic acid and ammonium sulfate as a function of relative humidity and aerosol composition using a laminar flow reactor coupled with a differential mobility analyzer (DMA) to characterize the aerosol. The concentration of liquid water in the aerosol droplets was calculated using the aerosol inorganic model and a new combined FTIR-DMA system.

An investigation was carried out about NO reaction processes on the (001) surface of CaO by using Ab initio molecular dynamics (MD). The results obtained indicate that the spectroscopy is silent to most of the nitrogen oxide species adsorbed on CaO powders, despite deposition of paramagnetic NO molecules at room temperature.

The five-coordinate NO-bound heme in cytochrome c' from an overexpressing variant of denitrifying R. sphaeroides 2.4.3 was investigated by proton, nitrogen, and deuterium Q-band ENDOR (electron nuclear double resonance). ENDOR frequencies from heme meso-protons, assigned with reference to porphyrin models, were determined to result from an anisotropic hyperfine tensor.

The nitrogen isotropic hyperfine coupling constant (hcc) and the g tensor of a phototypical spin probe (dl-tert-butyl nitroxide, DTBN) in aqueous solution was investigated by means of an integrated computational approach including Car-Parinello molecular dynamics and quantum mechanical calculations involving a discrete-continuum embedding. The quantitative agreement between computed and experimental parameters fully validates the integrated approach.

A study is conducted to characterize the Ti-MCM-41 mesoporous molecular strains using X-ray absorption near-edge structure and extended X-ray absorption fine structure, UV-vis, and Fourier transform infrared spectroscopy. The results found that an increase in the Ti content caused the structure of the Ti-oxides in Ti-MCM-41 to change from an isolated tetrahedral coordination to adjacent Ti-oxide species with Ti(super 4+) of tetrahedral coordination.

Formation of the ground-state nitrogen atom, N((super 4)S), following 193.3-nm ArF laser irradiation of NO and NO2 is detected directly by a technique of laser-induced fluorescence spectroscopy at 120.07 nm. The rate constants for the reactions of N((super 4)S) with NO and NO2 are determined to be (3.8 plusmn 0.2) x 10(super -11) and (7.3 plusmn 0.9) x 10(super -12) cm(super 3) molecule(super -1)s(super -1), respectively.

The infrared spectra of the CH3Cl:NO complex isolated in solid neon are investigated detecting most of the vibrational modes of the complex and on the basis of DFT calculations, different geometries are explored for the complex. The weak interaction between NO and CH3CI in CH3Cl:NO is responsible for small shifts of the vibrational mode frequencies of both CH3CI and NO molecules and the most stable structure is of C1 symmetry.

The rebinding kinetics of NO to the heme iron of myoglobin (Mb) is investigated as a function of temperature. The first comprehensive measurements of the temperature-dependent NO rebinding kinetics of Mb and its distal pocket mutants are presented.

The N(sub 2)O-mediated oxidative dehydrogenation of propane (ODHP) to propylene was investigated in the temperature range of 673-773 K over stream-activated FeMFI zeolites with different framework compositions. A tapered element oscillating microbalance (TEOM) coupled to on-line analysis products were applied to simultaneously monitor activity and mass changes during the ODHP reaction.

MCM-48, SBA-15, MCF and MSU mesoporous silicas are used as supports for a deposition of Fe oxide species. The Fe-containing mesoporous silicas are found to be active catalysts for the oxidative dehydrogenation of ethylbenzene to styrene in the presence of nitrous oxide.

An alternate three-component model for the density ([M]) and temperature dependence of the N2O quantum yields in the UV photolysis of O3 in air is presented. The [M]-independent component is especially significant despite being small compared to the dominant [M](super 1) component.

The mechanism of the formation of supercooled ternary H2SO4/H2O/HNO3 solution droplets in the polar winter stratosphere is mimicked during a simulation experiment at a large coolable aerosol chamber. The results shows that the implementation of a mixing rule approach, that is calculating the refractive indices of ternary H2SO4/H2O and HNO3 solution droplets based on accurate reference data sets for the two binary H2SO4/H2O and HNO3/H2O systems, is justified.

The generation and reactivity of the nitrosyl complex [Ru(tpy)(dpk)(NO)](super 3+) ([4)](super 3+) is studied using the complex framework [Ru(tpy)(dpy)](super 2+). The stepwise synthesis, X-ray structures, and spectroelectrochemical properties of the complexes [Ru-(tpy)(dpk)(CI)](ClO(sub 4)) = [1](ClO(sub 4))->[Ru(tpy)(dpk)(CH(sub3)-CN)](ClO(sub4)(sub2) = [2](ClO(sub4)(sub2) =>[Ru(tpy)(dpk)(NO(sub2)](ClO(sub4) = [3](ClO(sub4) -> [Ru(tpy)(dpk)(NO)](ClO(sub4)(sub3) = [4](ClO(sub4)(sub3) is reported.

A mass spectrometry method is presented for the identification of compounds that contain the primary N-oxide functional group. This method utilizes a gas-phase ion molecule reaction with dimethyl disulfide that rapidly and selectively derivatizes the protonated primary N-oxide functional group in a mass spectrometer to yield an ionic reaction product (with 31 Da higher mass than that of the protonated molecule) that is diagnostic for the presence of a primary N-oxide functionality. A variety of protonated analytes containing different functional groups were tested in Fourier transform ion-cyclotron resonance and triple quadrupole mass spectrometers to probe the selectivity of the reaction. Only molecules containing the protonated primary N-oxide functional group yielded the diagnostic reaction product; all other protonated molecules gave protonated dimethyl disulfide or no reaction products. The feasibility of this method for compound screening was tested by examining six analytes with the same molecular formula but different atom connectivity. The one analyte that contained the primary N-oxide functional group was readily differentiated from the other analytes.

N-Oxides are known to undergo deoxygenation during atmospheric pressure chemical ionization (Ramanathan, R.; Su, A.-D.; Alvarez, N.; Blumenkrantz, N.; Chowdhury, S. K.; Alton, K.; Patrick, J. Anal. Chem. 2000, 72, 1352-1359) resulting from thermal energy activation at the vaporizer of the APCI source. In addition to deoxygenation, tert-N-oxides containing an alkyl or benzyl group on the N-oxide nitrogen also undergo an N-R to O-R rearrangement (Meisenheimer arrangement, where R = alkyl or benzyl), followed by elimination of an aldehyde (or a ketone) through an internal hydrogen transfer. This has been observed under both atmospheric pressure chemical ionization and atmospheric pressure photoionization conditions. These fragment ions were not observed in the product ion spectra from the protonated molecules of the corresponding N-oxides. The elimination of an aldehyde or a ketone, thus, results from thermal energy activation at the vaporizer and is not induced by collisional activation. These fragmentations not only distinguish N-oxides from isomeric hydroxylated metabolites but also provide a potential way to determine the position of N-oxidation when a metabolite (or molecule) contains multiple N-oxidation sites that are in different chemical environments.

A study is conducted which report computations with CBS-QB3 for gas-phase free energies and PCM or CPCM for aqueous solvation energies. Computational predictions potentials of reactive nitrogen oxides are described.

The activation parameters of the pericyclic Meisenheimer rearrangement and a competitive rearrangement of N-propargylmorpholine N-oxide are determined by experimental and computational methods. A number of aprotic and protic solvents of different polarities and hydrogen bond-forming abilities and the roles of electron-pair acceptor additives are investigated.

The rate constants for the gas-phase reaction of isopropyl- and tert-butylperoxy radicals with nitric oxide (NO) are studied at 298 plusmn 2 K and a total pressure of 3-4 Torr. The results in combination with the earlier studies are discussed in terms of the systematic reactivity of alkyl peroxy radicals toward NO.

The unstable trifluoroacetonitrile N-oxide molecule, CF3CNO, is generated in high yield in the gas phase from CF3BrC=NOH and studied by gas-phase mid-infrared spectroscopy. The CCN bending potential in CF3CNO is explored at the CCSD(T)(fc)/cc-pVT level, with results suggesting that CF3CNO exhibits strong quasi-symmetric top behavior with a barrier to linearity of 174 cm(super -1).