Small Amounts Of NO Research Articles

Collisional relaxation and internal energy redistribution in NO 2 investigated by means of laser-induced thermal grating technique

Optical scattering from laser-induced thermal gratings (LITGs) was employed in investigations of molecular relaxation processes in gas mixtures containing a small amount of NO 2 diluted with different buffer gases (N 2,Ar,CO 2). The thermal gratings were generated by the thermalization of the molecular internal energy stored in the NO 2 molecules after laser resonant excitation of the 2 B 1← 2 A 1 Huber–Douglas band. The temporal evolution of LITGs was detected by scattering a cw read-out laser beam. A theoretical simulation of experimental results was performed in which the linearized hydrodynamic equations relevant to collisions responsible for the relaxation process were solved by following a two-step rate equations approach.

The effects of reaction pressures on the production of methanol through the selective oxidation of methane in CH 4–O 2–NO x ( x=1 or 2)

The effects of reaction pressures on the selective formation of methanol in a gas phase selective oxidation of CH 4 with NO x ( x=1 or 2) were examined. Methane conversion was enhanced by the addition of a small amount of NO x (0.125–1.50% ) in a feed gas and also enhanced by raising reaction pressures. The transition barrier of hydrogen abstraction from methane with NO 2, i.e. CH 4+NO 2→CH 3 +H–NO 2 was lower than that with O 2, and the number of these reactions between CH 4 and NO 2 in a higher pressure reactor was increased. A lower reaction temperature was favorable to enhance the selectivity of CH 3OH, and a shorter mean free path in a higher-pressure reactor simultaneously increased the subsequential oxidation of CH 3OH. The optimum pressure for the production of methanol at 4% conversion of CH 4 was 1.0 MPa for the selective oxidation of methane with 0.50% NO.

Improvement of NOx Removal Efficiency Assisted by Aqueous-Phase Reaction in Corona Discharge

The influence of water vapor and water droplets on the removal efficiency of nitrogen oxide is investigated in the pulsed positive corona discharge in atmospheric pressure air-based gas with a small amount of NO. The removal rates of both NO and NO2 are improved by feeding water vapor into the discharge reactor since NO2 is transformed into HNO3 by reaction with OH. Feeding water droplets, particularly alkaline water droplets, gives a better NO and NO2 removal efficiency than feeding water vapor. This might be explained by the rapid dissolution of the generated HNO3 into water droplets. Numerical modelling by means of a rate equation is carried out to investigate the dynamic process of gas phase and aqueous phase, and the aqueous-phase reaction in water droplets. The results suggest that gas-phase HNO3 dissolves in water droplets within short time (∼0.1 s). Therefore, the efficient transformation of NOx into gas-phase HNO3 is a key process in the improvement of NOx removal efficiency. Suppressing hydrogen ion concentration in water droplets by adding NH3 or feeding alkaline water droplets improves the dissolution rate of NO2.

Effect of NO on D 2 adsorption on the Pt(100)–(hex) surface

The influence of NO on the adsorption of D 2 on the Pt(100)–(hex) surface was studied by means of temperature-programmed reaction (TPR). Deuterium adsorbs negligibly on Pt(100)–(hex) at T=270 K, whereas an addition of a small amount of NO to D 2 increases drastically the adsorption capacity of Pt(100)–(hex) towards deuterium. The same phenomenon was observed on the surface pre-covered with NO ads as well. As the NO ads pre-coverage increases, the uptake of D ads first increases, then reaches a maximum at θ NO≈0.25 ML, and finally falls down to zero for the NO ads saturated layer. The following explanation is supposed. Upon adsorption on the Pt(100)–(hex) surface, NO lifts the (hex) reconstruction and forms the dense NO ads/(1×1) islands surrounded by the clean (hex) surface. A limited area of the (hex) phase, which is immediately adjacent to the boundaries of the NO ads/(1×1) islands, is supposed to be distorted and could be able to adsorb deuterium.

An FTIR product study of the reaction between HCO and NO2

The product distribution of the reaction (1a) $$\rm\longrightarrow OH+NO+CO$$(1b) $$\rm\longrightarrow HNO+CO_{2}$$(1c) $$\rm\longrightarrow H+NO+CO_{2}$$(1d) $$\rm\longrightarrow HCO_{2}+NO$$(1e) (1f) (1g) was investigated at room temperature in the gas phase in Ar buffer gas at 570 mbar pressure by Fourier transform infrared (FTIR) spectroscopy. Mixtures of NO2/H2CO/Ar were photolyzed under stationary conditions using a high-pressure Hg lamp at λ = 300–340 nm. NO, CO, CO2, HONO, and H2O were found as major reaction products. A small amount of N2O was detected at long reaction times. From the yields of CO and CO2, branching ratios were found to be (k1a + k1b)/k1 = (0.66 ± 0.10) and (k1c + k1d + k1e)/k1 = (0.34 ± 0.10). The formation of HONO was attributed to reaction (1a) and/or reaction (1c) followed by the reaction HNO + NO2 NO + HONO with a combined branching ratio of (k1a + k1c)/k1 = (0.28 ± 0.10). © 2000 John Wiley & Sons, Inc. Int J Chem Kinet 32: 136–145, 2000

Effects of NO on the ignition of hydrogen and hydrocarbons by heated counterflowing air

Experiments were carried out to study the influence of NO in air on the ignition temperature of hydrogen and hydrocarbons in a nonpremixed counterflowing system. These experiments were performed from 0.5 to 6 atm, with the NO concentration varying from 100 ppm to 15,000 ppm. It is shown that addition of a small amount of NO in air significantly reduces the ignition temperature of all fuels. For hydrogen, under certain pressures, NO eventually becomes an inhibitor at higher levels of addition. Thus there appears to exist an optimal NO concentration at which the catalytic effect is the most pronounced, and this optimal concentration was found to also depend on the system pressure. Numerical simulation was performed in the hydrogen case to better understand the kinetics of the observed phenomenon. It was found that at low NO concentrations, the ignition temperature was determined by the interaction of the H 2-O 2-NO subsystem, whereas at high NO concentrations the ignition temperature was mostly affected by the NO x chemistry. For hydrocarbons, the minimum temperature was much less pronounced and in most cases nonexistent. Furthermore, the extent of temperature decrease depended on the nature of the fuel.

Expression of inducible nitric oxide synthase (iNOS/NOS II) in the cochlea of guinea pigs after intratympanical endotoxin-treatment

Since NO is believed to be involved in cochlear physiology, presence of the constitutive isoforms of nitric oxide synthase (NOS), and the target enzyme of NO, soluble guanylyl cyclase (sGC) in structures of the mammalian cochlea have been demonstrated. To date, no reports have been published regarding the detection of the inducible isoform (NOS II) in the cochlea. In order to show the capability of iNOS expression in cochlear tissue, a mixture of proinflammatory bacterial lipopolysaccharides (LPS) and tumor necrosis factor α (TNF-α) was injected into the tympanic cavity of guinea pigs, vs. saline-solution as control. Paraffin sections of LPS/TNF-α treated and saline-treated cochleae (6 h) were examined immunohistochemically with specific antibodies to neuronal, endothelial and inducible NOS and to sGC. Initiated expression of iNOS in the cochlea was observed in the wall of blood vessels of the spiral ligament (SL) and the modiolus, in supporting cells of the organ of Corti, in the limbus, in nerve fibers and in a part of the perikarya of the spiral ganglion after LPS/TNFα-treatment. iNOS was not detected in saline-treated control tissue. Expression of both constitutive NOS-isoforms (endothelial and neuronal NOS) and of sGC showed no significant differences in both experimental groups. Endothelial eNOS and neuronal bNOS were detected co-localized in ganglion cells, in nerve fibers, in cells of the SL and in supporting cells of the organ of Corti, but not in sensory cells. Strong labeling for bNOS became evident in the endosteum of the cochlea, while in the endothelium of blood vessels and in the epithelium of the limbus only eNOS could be labeled. sGC could be detected in SL, in supporting and sensory cells of the organ of Corti, in nerve fibers, ganglion cells, in the wall of blood vessels and in the limbus-epithelium. While small amounts of NO, generated by bNOS and eNOS, seem to support the cochlear blood flow and auditory function as well as neurotransmission, high amounts of iNOS-generated NO could have dysregulative and neurotoxic effects on the inner ear during bacterial and viral infections of the middle and inner ear.

NO adsorption and decomposition on La 2O 3 studied by DRIFTS

In situ diffuse reflectance Fourier transform infrared spectroscopy (DRIFTS) was performed to study the reaction mechanism of NO decomposition on La 2O 3. Peak assignments were verified by establishing isotope shifts of species formed after adsorption of 15 NO . Peak deconvolution was employed to resolve complex spectra. The adsorption behavior of NO was established at 298 K as well as temperatures up to 773 K. Upon adsorption at room temperature, NO −, N 2O 2− 2, chelating NO − 2, nitrito (NO − 2), and unidentate and bidentate NO − 3 groups are observed, whereas at higher temperatures, nitrate and smaller amounts of NO − 2 groups prevail. A surface reaction model developed on the basis of the solid-state properties of La 2O 3 reveals that the anionic NO species (NO −, N 2O 2− 2) are formed by adsorption on anion vacancies and that they decompose at higher temperatures to yield nitrogen and oxygen. NO adsorption onto basic oxygen anion creates NO − 2 and NO − 3 spectator species; however, NO − 2 groups may also be involved in the decomposition process by reacting with the remaining oxygen to form nitrates. The surface reaction model is in agreement with a sequence derived from kinetic modeling.

Pulse Intense Electron Beam Irradiation on the Atmospheric Pressure N2 Containing 200 ppm of NO

Removal of nitrogen oxides (NOx) in N2 by the pulse intense electron beam irradiation was investigated. The pulse electron beam (kinetic energy; ≤160 keV, current; ∼140 A, current density; ∼2 A/cm2, pulse width; ∼700 ns and the electron beam energy in one pulse; 12.6±0.4 J) was injected into a gas cell filled with 1 atmospheric pressure N2 with an initial concentration of 200 ppm of NO. The NOx decreased quickly and only a small amount of NO2 was produced by the electron beam irradiation. Electron impact dissociation of N2 and the subsequent chemical reduction of NO by nitrogen radicals was occurred. The typical removal ratio in the gas cell of 1.7 l was about 20% for the first shot and reached to 95% after 8 successive shots. This removal ratio corresponds to the removal efficiency of 220–300 nmol/J. The NOx removal ratio and the efficiency which depended on the length of the gas cell, the filling pressure, the initial concentration of NO, the electron beam energy in one pulse and the axial magnetic field were investigated.

Nitric Oxide Synthase in Diabetic Retinopathy in the BBZ/WOR Rat: An Immunocytochemical Study

Abstract Nitric oxide synthase (NOS) catalyzes the conversion of L-arginine to citrulline and the highly reactive free radical species, NO. Two major constitutive isoforms, neuronal and endothelial NOS, have been ented in the retina. These constitutive isoforms produce small amounts of NO while the inducible isoform, iNOS, produces high levels of NO. Excess production of NO by iNOS has beem implicated in the complications of diabetes. Since NO is a highly labile molecule, its potential localization is best achieved by immunocytochemical studies of NOS. Semiquantitative colloidal gold labeled immunocytochemical studies of endothelial NOS (eNOS) and iNOS were done on sections of neural retina in eyes of obese, noninsulin dependent diabetic BBZ/Wor rats with diabetes of five months to twelve months duration. Age matched, nondiabetic control retinas were from eyes from BBDR/Wor rats. Levels of iNOS were elevated in diabetic (33.9 ± 10.0 gold particles) as compared to age matched nondiabetic control (3.5 ± 2.8 gold particles) retinas.

The influence of nitrogen dioxide on the oxidation of UO 2 in air at temperatures below 275°C

Specimens of polycrystalline, sintered UO 2 were cut from unirradiated CANDU fuel, and heated in air or air+NO 2 mixtures (up to 1 vol.% NO 2), to investigate the effects of nitrogen oxides on the rates of oxidation to U 3O 7 and U 3O 8. Oxidized specimens were analyzed by X-ray diffraction (XRD) and X-ray photoelectron spectroscopy to determine the extent of surface oxidation. The kinetic expression for the formation of U 3O 7 was initially parabolic, but switched to linear at long reaction times. The first, parabolic stage of oxidation to U 3O 7 was accelerated slightly by the addition of small quantities of NO 2 to air, probably because NO 2 increases the oxygen potential of the outermost surface of the UO 2 by forming a thin film of UO 3. The rate of oxidation in the region of linear kinetics is approximately the same for all atmospheres up to 1.0% NO 2. The effect of NO 2 on the rate of U 3O 8 formation is difficult to ascertain because of the close similarity between the XRD patterns of α-UO 3 and U 3O 8. However, it appears that there is a substantial increase in the rate of formation of higher oxides (U 3O 8 and possibly also UO 3) in the presence of NO 2. These results indicate that the effect of nitrogen oxides (which are formed by radiolysis of air) should be included in detailed models of air oxidation of irradiated fuel.

Nitrite production from the oxidation of salicylhydroxamic acid by peroxidase or Mn(II)

Horseradish peroxidase or green algal cells catalyzed the NADH-dependent and oxygen-consuming oxidation of salicylhydroxamic acid (SHAM) to generate NO 2 −. NO 2 − production was inhibited by superoxide dismutase or catalase. In the absence of HRP, NO 2 − could also be produced from non-enzymatic SHAM oxidation by Mn(II). These results suggest that the peroxidase activators may lead to erroneous conclusions regarding the presence of extracellular or plasma membrane nitrate reductase. Horseradish peroxidase (HRP) catalyzed the NADH-dependent and oxygen-consuming oxidation of salicylhydroxamic acid (SHAM) to generate NO 2 −. The reaction ceased when NADH was depleted, and could be re-initiated by further addition of NADH. NO 2 − production was inhibited by superoxide dismutase or catalase. Hydoxylamine could also serve as a substrate for HRP-catalyzed NO 2 − production. Selenastrum minutum, a unicellular green alga with high extracellular peroxidase activity, also produced small amounts of NO 2 − in the presence of SHAM and NADH. In the absence of HRP or algal cells, NO 2 − could also be produced from non-enzymatic SHAM oxidation by Mn(II), in a reaction that was not sensitive to inhibition by superoxide dismutase or catalase. These results suggest that under certain conditions it is possible to generate NO 2 − in the absence of NO 3 − or nitrate reductase activity, and that the commonly-employed peroxidase activators SHAM and Mn(II) may lead to erroneous conclusions regarding the presence of extracellular or plasma membrane-associated nitrate reductase.

The influence of ethene on the conversion of in a dielectric barrier discharge

The possibility of removing toxic impurities from gaseous streams by electrical gas discharges has been investigated for almost a decade. Cold discharges, i.e. plasmas in which the electrons are not in thermal equilibrium with ions and molecules, seem to be a potential method for the conversion of (, ) in exhaust gases of cars or in flue gases of incineration plants. In this work we present a model for the temporal evolution of the plasma chemical processes in a dielectric barrier discharge in a mixture containing , , O and small amounts of NO, and optionally H (ethene). The results of the calculations are compared with our experimental data. Quantitative analysis of the reaction turnovers allows the identification of the main chemical pathways. Most of the conversion of is due to oxidation and only a small fraction is caused by chemical reduction. The complete removal of NO can be achieved at an energy expense of 5 to 10 eV per NO molecule if 2000 ppmv H are present in the gas stream. If H is not present 60 eV/NO are needed.

Effect of dimethyl ether, NO x, and ethane on CH 4 oxidation: High pressure, intermediate-temperature experiments and modeling

The effects of small amounts of dimethyl ether (DME), NO, and NO 2 on the autoignition and oxidation chemistry of methane, with an without small amounts of ethane present, were experimentally studied in a flow reactor at pressures and temperatures similar to those found in spark- and compression-ignition engines (under autoignition conditions). The reactions were studied at pressures from 10 to 18 atm, temperatures from 800 to 1060 K, and equivalence ratios from 0.5 to 2.0. It is found that 1% DME addition is as effective in stimulating the autoignition and oxidative behavior of methane as 3% C 2 H 6 addition, and that NO x at even ppm levels is more effective than hydrocarbon additives. For the same reaction time and temperatures below 1200 K, addition of small amounts of NO x lowered the temperature at which reaction becomes significant by more than 200 K. Chemical kinetic mechanisms in the literature for the interactions of methane, ethane, and NO x do not predict the reported observations well. The most significant rate-controlling reactions for CH 4 autoignition is found to be CH 3 +HO 2 =CH 3 O+OH. Good agreement, with and without NO x perturbations can be obtained by modifying the rate constants of three reactions (CH 3 +HO 2 =CH 3 O+OH; CH 3 +HO 2 =CH 4 +O 2 : CH 2 O+HO 2 =HCO+H 2 O 2 ) and by adding the reaction CH 3 +NO 2 =CH 3 O+NO to the GRI-Mech v2.11 mechanism. These modifications do not significantly affect predictions for shock tube, flame, and other results used in developing GRI-Mech v2.11. Results strongly suggest that exhaust gas residuals and/or exhaust gas recirculation can have as profound an effect as natural gas contaminants on the apparent octane and cetane behavior.

Measurement of the rate constant for H+O 2+M→HO 2+M (M=N 2, Ar) using kinetic modeling of the high-pressure H 2/O 2/NO x reaction

The reaction of dilute H2/O2/N2 and H2/O2/Ar mixtures perturbed with small quantities of NO has been studied in a variable-pressure flow reactor between 800 and 900 K. At high pressures (10–14 atm), the consumption of H2 and the conversion of NO to NO2 were highly sensitive to the pressure-dependent reaction {fx1} Rate coefficient data for the low-pressure limit {fx2} were inferred by comparison of the experimental data with a reaction mechanism that uses the high-pressure limit k2,∞=4.52×1013 (T/300)0.6 with FcN2=0.5 and FcAr=0.45. The data obtained with M=Ar are consistent with previous shock-tube data at comparable temperatures and are in good agreement with recent recommendations for k2,0Ar. However, the data obtained for M=N2 are 40% lower than recent recommendations and are combined with previously published data to yield {fx3} over the temperature range 300–1600 K. The rate coefficient data obtained in this study are insensitive to the competing reaction {fx4} and, when used with the k1 recommendation from Pirraglia et al. [27], are in good agreement with H2/O2 explosion limit data in the intermediate temperature range of 700\2-900K.

Determination of the isomerization rate constant HOCH2CH2CH2CH(OO�)CH3 ?HOC�HCH2CH2CH(OOH)CH3. Importance of intramolecular hydroperoxy isomerization in tropospheric chemistry

The rate constant of the title reaction is determined during thermal decomposition of di-n-pentyl peroxide C5H11O()OC5H11 in oxygen over the temperature range 463–523 K. The pyrolysis of di-n-pentyl peroxide in O2/N2 mixtures is studied at atmospheric pressure in passivated quartz vessels. The reaction products are sampled through a micro-probe, collected on a liquid-nitrogen trap and solubilized in liquid acetonitrile. Analysis of the main compound, peroxide C5H10O3, was carried out by GC/MS, GC/MS/MS [electron impact EI and NH3 chemical ionization CI conditions]. After micro-preparative GC separation of this peroxide, the structure of two cyclic isomers (3S*,6S*)3α-hydroxy-6-methyl-1,2-dioxane and (3R*,6S*)3α-hydroxy-6-methyl-1,2-dioxane was determined from 1H NMR spectra. The hydroperoxy-pentanal OHC()(CH2)2()CH(OOH)()CH3 is formed in the gas phase and is in equilibrium with these two cyclic epimers, which are predominant in the liquid phase at room temperature. This peroxide is produced by successive reactions of the n-pentoxy radical: a first one generates the CH3C·H(CH2)3OH radical which reacts with O2 to form CH3CH(OO·)(CH2)3OH; this hydroxyperoxy radical isomerizes and forms the hydroperoxy HOC·H(CH2)2CH(OOH)CH3 radical. This last species leads to the pentanal-hydroperoxide (also called oxo-hydroperoxide, or carbonyl-hydroperoxide, or hydroperoxypentanal), by the reaction HOC·H(CH2)2CH(OOH)CH3+O2O()CH(CH2)2CH(OOH)CH3+HO2. The isomerization rate constant HOCH2CH2CH2CH(OO·)CH3HOC·HCH2CH2CH(OOH)CH3 (k3) has been determined by comparison to the competing well-known reaction RO2+NORO+NO2 (k7). By adding small amounts of NO (0–1.6×1015 molecules cm−3) to the di-n-pentyl peroxide/O2/N2 mixtures, the pentanal-hydroperoxide concentration was decreased, due to the consumption of RO2 radicals by reaction (7). The pentanal-hydroperoxide concentration was measured vs. NO concentration at ten temperatures (463–523 K). The isomerization rate constant involving the H atoms of the CH2()OH group was deduced: or per H atom: The comparison of this rate constant to thermokinetics estimations leads to the conclusion that the strain energy barrier of a seven-member ring transition state is low and near that of a six-member ring. Intramolecular hydroperoxy isomerization reactions produce carbonyl-hydroperoxides which (through atmospheric decomposition) increase concentration of radicals and consequently increase atmospheric pollution, especially tropospheric ozone, during summer anticyclonic periods. Therefore, hydrocarbons used in summer should contain only short chains (<C4) hydrocarbons or totally branched hydrocarbons, for which isomerization reactions are unlikely. © 1998 John Wiley & Sons, Inc. Int J Chem Kinet 30: 875–887, 1998

The fate of char-nitrogen in low-temperature oxidation

Nitrogen release during the oxidation of coal char has been studied in a thermogravimetric analyzer (TGA) at 873 K with 2% O2 in He. Species profiles are determined using Fourier transform infrared (FTIR) spectroscopy (NO, NO2, CO, CO2, N2O, and HCN) and high-speed gas chromatography (N2), which allows all of the char-N to be accounted for in the gas phase. Char-N is released predominantly as N2 with smaller amounts of NO and HCN also present. The proportion of char-N released to the gas phase as N2, NO, and HCN is relatively constant throughout burnout. At the low-temperature conditions of this study, N2O is not produced and the results suggest that HCN is a primary product formed via heterogeneous oxidation and not by slow or secondary devolatilization. The gaseous product species profiles suggest that nitrogen is preferentially retained in the char as the carbon is oxidized and this is confirmed directly by X-ray photoelectron spectroscopy (XPS) and elemental analysis of partially oxidized char samples. Analysis of the XPS results also shows that enrichment of the char in nitrogen is a surface effect that occurs with an increase in the pyridinic N content of the char relative to pyrrolic N. At low temperatures, the enrichment of the char in nitrogen as burnout proceeds is the major contributing factor to the increase in the [NO]/([CO2]+[CO]) ratio.

Adsorption and reactions of NO on NiAl(111) at 75 K

The adsorption and reactions of NO on NiAl(111) at 75 K were studied by high resolution electron energy loss spectroscopy, temperature programmed desorption, Auger electron spectroscopy, and low energy electron diffraction. At low exposure (⩽1 L), NO mainly adsorbs molecularly on top in an upright geometry on Ni atoms. Simultaneously, a small amount of NO dissociates. Higher exposures (⩾2 L up to saturation) lead to the formation of a thin amorphous Al-oxynitride (am-ALON) film. In the presence of am-ALON, a molecular adsorption of NO on am-ALON sites and/or in the neighborhood of ALON islands is observed. Besides the upright geometry, NO molecules are adsorbed in disarranged (bent or tilted) configurations. The growing am-ALON film acts as a catalyst for the reduction of NO to N2O. Substantial amounts of N2O are formed for NO exposures higher than 5 L, and are coadsorbed molecularly. The main thermal desorption products are N2O, N2, and NO. For an exposure of 20 L NO, the ratios of the amounts of desorbing molecules are: N2O:N2:NO=1:0.43:0.36. It could be shown that the N2 signal is due to a recombinative desorption of adsorbed nitrogen atoms.

Nitric Oxide Determinations: Much Ado About NO•-Thing?

The nitric oxide radical (NO•) is an important mediator of both physiological and pathophysiological processes. NO• is produced by nitric oxide synthase (NOS; EC 1.14.13.39), an enzyme that exists in three isoforms encoded by distinct genes (1)(2). All isoforms of NOS catalyze the conversion of l-arginine into citrulline and NO•. In this reaction, which requires oxygen and NADPH, a guanidino-nitrogen atom of l-arginine is incorporated into NO•. Neuronal NOS (type I, nNOS) and endothelial (type III, eNOS) are Ca2+- and calmodulin-dependent constitutive NOS isoforms. nNOS has a function in neurotransmission. NO• produced by eNOS is identical to endothelium-derived relaxing factor and is the principal signal for relaxation of vascular smooth muscle cells. In addition, NO• produced by the endothelium has antithrombotic actions. Thus, eNOS and nNOS isoforms have important functions under normal conditions. They are present intracellularly, are rapidly activated by intracellular Ca2+ fluxes, and produce small quantities of NO•. Inducible NOS (iNOS, type II) is not expressed under normal conditions. iNOS is induced by cytokines and (or) endotoxin during inflammatory and infectious processes and produces abundant amounts of NO• for extended periods. iNOS can be induced in many cell types, including hepatocytes, macrophages, neutrophils, smooth muscle cells, and chondrocytes. Induction of iNOS requires de novo protein synthesis. NO• produced by iNOS has antimicrobial activity and may be involved in killing tumor cells. As such, it is part of the nonspecific host defense system. Increased expression of iNOS has been demonstrated in a wide range of disorders, including sepsis, asthma, rheumatoid arthritis, atherosclerotic lesions, tuberculosis, inflammatory bowel disease, Helicobacter pylori-induced gastritis, allograft rejection, Alzheimer disease, and multiple sclerosis (3)(4)(5)(6)(7)(8)(9 …

Analysis of the flame formed during oxidation of pulverized coal by an O 2CO 2 mixture

Pulverized coal combustion with oxygen and recycled flue gas constitutes a promising system to recover CO 2 from the exhaust gases of boilers. Our previous combustion tests on this system suggest emissions of smaller amounts of NO x than in conventional combustion and reduced ignition stability of the burner. In order to improve the combustibility of the O 2/CO 2-pulverized-coal burner, numerical simulations and combustion tests were performed. An oxygen-injection nozzle was added to the burner. Simulation results predicted the effectiveness of direct oxygen injection and were confirmed qualitatively by bench-scale combustion tests on gas temperatures.