Absence Of NO Research Articles

Effects of riociguat in severe experimental pulmonary hypertension

The NO-sGC-cGMP signaling pathway is impaired in different cardiovascular diseases, including pulmonary hypertension (PH). Riociguat is the first of a new class of drugs, the soluble guanylate cyclase stimulators. Riociguat has a dual mode of action: it sensitizes sGC to the body’s own NO and can also increase sGC activity in the absence of NO, causing vasorelaxation, anti-proliferation and anti-fibrotic effects. The aim of the study was to investigate the effects of riociguat as compared to the PDE5 inhibitor sildenafil on pulmonary vascular remodeling in severe experimental PH.

Kinetics and mechanism of the reaction of propylene oxide with chlorine atoms and hydroxy radicals

The kinetics and mechanism of gas-phase propylene oxide (PPO) reactions were studied in a 142-L reaction chamber by long-path Fourier transform infrared spectroscopy at atmospheric pressure and 298 K. Rate coefficients for the reaction of PPO with ozone (O3), chlorine atoms (Cl), and hydroxyl radicals (OH) were measured using the relative rate technique. Product yields of acetic acid, acetic formic anhydride, formic acid, and carbon monoxide were determined for the following reactions: PPO with Cl both in the presence and absence of NO, PPO with OH and NO, methyl acetate with Cl both in the presence and absence of NO, and ethyl formate with Cl both in the presence and absence of NO. The measured rate coefficients for PPO with O3, Cl, and OH are <3.5 × 10−21 cm3 molecule−1 s−1, (3.0 ± 0.7) × 10−11 cm3 molecule−1 s−1, and (3.0 ± 1.0) × 10−13 cm3 molecule−1 s−1, respectively. The carbon balance for the products measured ranged from 10% (for OH + PPO) to 100% (for Cl + methyl acetate in the absence of NO). The mechanistic and atmospheric implications of these measurements are discussed. © 2011 Wiley Periodicals, Inc. Int J Chem Kinet 43: 507–521, 2011

Cyclooxygenase-2-Derived Prostacyclin Protective Role on Endotoxin-Induced Mouse Cardiomyocyte Mortality

Cardiovascular dysfunction characterizes septic shock, inducing multiple organ failure and a high mortality rate. In the heart, it has been shown an up-regulation of inducible nitric oxide synthase (iNOS) and cyclooxygenase-2 (COX-2) expressions with subsequent overproduction of nitric oxide (NO) and eicosanoids. This study is focused on the links between these products of inflammation and cell loss of mouse cardiomyocytes during treatment by the Salmonella typhimurium lipopolysaccharide (LPS) in presence or in absence of NOS or COX inhibitors. LPS induced RelA/NF-κB p65 activation, iNOS and COX-2 up-regulations, resulting in NO and prostacyclin releases. These effects were reversed by the NO-synthase inhibitor and increased by the specific COX-2 inhibitor. Immunostainings with FITC-conjugated anti-Annexin-V and propidium iodide and caspase 3/7 activity assay showed that cardiomyocyte necrosis was inhibited by L-NA during LPS treatment challenge, while apoptosis was induced in presence of both LPS and NS-398. No effect on LPS cellular injury was observed using the specific cyclooxygenase-1 (COX-1) inhibitor, SC-560. These findings strongly support the hypothesis of a link between iNOS-dependent NO overproduction and LPS-induced cell loss with a selective protective role allotted to COX-2 and deriving prostacyclins.

Kinetics of the Reactions of OH Radicals with 2- and 3-Methylfuran, 2,3- and 2,5-Dimethylfuran, andE- andZ-3-Hexene-2,5-dione, and Products of OH + 2,5-Dimethylfuran

Furan and alkylfurans are present in the atmosphere from direct emissions and in situ formation from other volatile organic compounds. The OH radical-initiated reactions of furan and alkylfurans have been proposed as relatively clean in situ sources of unsaturated 1,4-dicarbonyls, some of which are otherwise not readily available. Using a relative rate method, rate constants at 296 ± 2 K for the gas-phase reactions of OH radicals with 2- and 3-methylfuran, 2,3- and 2,5-dimethylfuran, and Z- and E-3-hexene-2,5-dione have been measured, of (in units of 10(-11) cm(3) molecule(-1) s(-1)): 2-methylfuran, 7.31 ± 0.35; 3-methylfuran, 8.73 ± 0.18; 2,3-dimethylfuran, 12.6 ± 0.4; 2,5-dimethylfuran, 12.5 ± 0.4; Z-3-hexene-2,5-dione, 5.90 ± 0.57; and E-3-hexene-2,5-dione, 4.14 ± 0.02. Products of the OH radical-initiated reaction of 2,5-dimethylfuran were investigated, with 3-hexene-2,5-dione being formed with molar yields of 24 ± 3% in the presence of NO and 34 ± 3% in the absence of NO. Direct air sampling atmospheric pressure ionization mass spectrometry showed the formation of additional products of molecular weight 114, attributed to CH(3)C(O)CH ═ CHC(O)OH and/or 5-hydroxy-5-methyl-2-furanone, and 128, attributed to CH(3)C(O)OC(CH(3)) = CHCHO.

Interaction between nitric oxide and dopaminergic transmission in the peripheral control of penile erection

As the peripheral role of dopamine in the mediation of penile erection was recently identified, its potential role in the modulation of NO action and whether D1 or D2 receptors are involved in this potential modulation was investigated. The isolated rabbit corpus cavernosum and measurement of intracavernosal pressure in the anesthetized rat model were used. The selective D1 antagonist SCH23390 but not the D2 antagonist sulpiride reduced the inhibitory effect of N(G)-nitro-L-arginine (L-NNA) and the potentiatory effect of sildenafil on erectile responses. L-NNA did not change the inhibitory effect of SCH23390 or the potentiatory effect of apomorphine but enhanced the effect of high-dose fenoldopam on intracavernosal pressure. Similarly, fenoldopam produced 47.30 ± 6.89% potentiation of relaxation of corpus cavernosum in absence of L-NNA and 80 ± 9.34% potentiation in its presence at 3 Hz. The effect of sildenafil was greatly reduced by pretreatment with SCH23390 or sulpiride and completely abolished by their combination. This study supports the role played by D1 receptors peripherally in the control of penile erection. Absence of NO may potentiate the effect of D1 receptor on erection. Activation of D1 receptors may be involved in the synthesis of NO in the corpus cavernosum or may activate the role of NO in erection.

HO2 formation from the OH + benzene reaction in the presence of O2

In this study we investigated the secondary formation of HO(2) following the benzene + OH reaction in N(2) with variable O(2) content at atmospheric pressure and room temperature in the absence of NO. After pulsed formation of OH, HO(x) (= OH + HO(2)) and OH decay curves were measured by means of a laser-induced fluorescence technique (LIF). In synthetic air the total HO(2) yield was determined to be 0.69 ± 0.10 by comparison to results obtained with CO as a reference compound. HO(2) is expected to be a direct product of the reaction of the intermediately formed OH-benzene adduct with O(2). The HO(2) yield is slightly greater than the currently recommended yield of the proposed HO(2) co-product phenol (∼53%). This hints towards other, minor HO(2) forming channels in the absence of NO, e.g. the formation of epoxide species that was proposed in the literature. For other test compounds upper limits of HO(2) yields of 0.10 (isoprene) and 0.05 (cyclohexane) were obtained, respectively. In further experiments at low O(2) concentrations (0.06-0.14% in N(2)) rate constants of (2.4 ± 1.1) × 10(-16) cm(3) s(-1) and (5.6 ± 1.1) × 10(-12) cm(3) s(-1) were estimated for the OH-benzene adduct reactions with O(2) and O(3), respectively. The rate constant of the unimolecular dissociation of the adduct back to benzene + OH was determined to be (3.9 ± 1.3) s(-1). The HO(2) yield at low O(2) was similar to that found in synthetic air, independent of O(2) and O(3) concentrations indicating comparable HO(2) yields for the adduct + O(2) and adduct + O(3) reactions.

A predictive kinetic model for inhibitory effect of nitrite on myeloperoxidase catalytic activity towards oxidation of chloride

Myeloperoxidase (MPO) is a neutrophil enzyme that employs hydrogen peroxide (H2O2) to catalyze the oxidation of chloride (Cl–) to hypochlorous acid (HOCl). Accepted mechanism is based on rapid reaction of native MPO with H2O2to produce Compound I (MPO-I) which oxidizes Cl– through a 2e– transition generating MPO and HOCl. MPO-I also reacts with H2O2 to generate Compound II (MPO-II) which is inactive in 2e oxidation of Cl–. Nitrite ( NO2-) inhibits the 2e oxidation of Cl– by reaction with MPO-I through 1e transition generating MPO-II and nitrite radical. H2O2 consumption during steady- state catalysis was monitored amperometrically by a carbon fiber based H2O2-biosensor at 25oC. Results demonstrated that in absence of NO2- reactions were monophasic and rapid (complete H2O2 consumption occurs in 2- increases, reactions change to biphasic (rapid step followed by a slow step) and both steps have been inhibited by NO2- . A predictive kinetic model describing the inhibittory effect of NO2- was developed and applied to experimental results The model is based on the assumption that MPO–I cannot be detected during steady-state catalysis. Calculated rate constants are in agreement with those obtained from pre-steady state kinetic methods.

Three-dimensionally ordered macroporous Ce0.8Zr0.2O2-supported gold nanoparticles: synthesis with controllable size and super-catalytic performance for soot oxidation

A series of catalysts of three-dimensionally ordered macroporous (3DOM) Ce0.8Zr0.2O2-supported gold nanoparticles with controllable sizes were successfully synthesized by the facile method of gas bubbling-assisted membrane reduction (GBMR). All the catalysts possess well-defined 3DOM structures, which consist of interconnected networks of spherical voids, and the Au nanoparticles are well dispersed and supported on the inner wall of the uniform macropore. The relationship between Au particle sizes and the ability to adsorb and activate oxygen was characterized by means of O2-TPD and XPS. The results show that the active oxygen species (O−) and gold ions with oxidation state of Au+ are essential for soot oxidation reaction. 3DOM Au0.04/Ce0.8Zr0.2O2catalyst with Au particle size of 2–3 nm has the strong capability of adsorption and activation of oxygen. Thus, it exhibits super-catalytic activity for diesel soot oxidation, especially at low temperature. The reaction pathways of catalytic soot oxidation in the presence or absence of NO can be outlined as follows: at low temperature ( 250 °C), the catalytic activity is strongly related to the NO gas, because NO2 derived from NO oxidation is used as intermediate to catalyze soot oxidation.

NO and C 3H 6 adsorption and coadsorption in oxygen excess—A comparative study of different type zeolites modified with gold

Non-acidic NaY, and acidic H-Beta and H-ZSM-5 with various Si/Al ratios were used as supports for gold loaded by deposition-precipitation method. Acidity of the pristine supports and Au/zeolites was estimated from adsorption of pyridine followed by FTIR spectroscopy measurements. NO selective reduction with propene (SCR-HC) was studied by the use of FTIR technique. Adsorption and co-adsorption of the reagents of NO SCR-HC (NO, C 3H 6 and O 2) allowed a discussion of the reaction pathways. The catalytic behaviour of NaY referring to the intermediate formed was not significantly changed by gold modification and Au/NaY did not activate the partial oxidation of propene in the absence of NO. Au particles in Au/Na-Y play an important role in the total oxidation to CO 2. The role of Brønsted acidity in Au/H-Beta and Au/H-ZSM-5 is on the oxidation of NO towards various intermediates (NO 2 −/NO 3 −, N 2O 4, NO +) and their further interaction with propene, whereas gold species enhance this process by inducing formation of additional active complex (Au n+ -NO). Moreover, gold species are responsible for the second reaction pathway via primary partial oxidation of propene to oxygenates and further reaction with NO and R-CN and R-NCO active intermediates as observed on Au/H-Beta and Au/H-ZSM-5.

Atmospheric Chemistry of i-Butanol

Smog chamber/FTIR techniques were used to determine rate constants of k(Cl + i-butanol) = (2.06 ± 0.40) × 10(-10), k(Cl + i-butyraldehyde) = (1.37 ± 0.08) × 10(-10), and k(OH + i-butanol) = (1.14 ± 0.17) × 10(-11) cm(3) molecule(-1) s(-1) in 700 Torr of N(2)/O(2) diluent at 296 ± 2K. The UV irradiation of i-butanol/Cl(2)/N(2) mixtures gave i-butyraldehyde in a molar yield of 53 ± 3%. The chlorine atom initiated oxidation of i-butanol in the absence of NO gave i-butyraldehyde in a molar yield of 48 ± 3%. The chlorine atom initiated oxidation of i-butanol in the presence of NO gave (molar yields): i-butyraldehyde (46 ± 3%), acetone (35 ± 3%), and formaldehyde (49 ± 3%). The OH radical initiated oxidation of i-butanol in the presence of NO gave acetone in a yield of 61 ± 4%. The reaction of chlorine atoms with i-butanol proceeds 51 ± 5% via attack on the α-position to give an α-hydroxy alkyl radical that reacts with O(2) to give i-butyraldehyde. The atmospheric fate of (CH(3))(2)C(O)CH(2)OH alkoxy radicals is decomposition to acetone and CH(2)OH radicals. The atmospheric fate of OCH(2)(CH(3))CHCH(2)OH alkoxy radicals is decomposition to formaldehyde and CH(3)CHCH(2)OH radicals. The results are consistent with, and serve to validate, the mechanism that has been assumed in the estimation of the photochemical ozone creation potential of i-butanol.

Product Study of the OH Radical and Cl Atom Initiated Oxidation of 1,3‐Dioxane

The products of the hydroxyl (OH) radical and chlorine (Cl) atom initiated oxidation of 1,3-dioxane are determined under various reaction conditions in a 50 L teflon reaction chamber using FTIR spectroscopy for analysis. The major products detected in all experiments are (2-oxoethoxy)methyl formate, formic acid and methylene glycol diformate with average molar yields of 0.50±0.05, 0.41±0.02 and 0.03±0.01 respectively for the OH initiated oxidation in the presence of NO(x). The yields of these products do not vary significantly with O(2) partial pressure or oxidising agent (OH or Cl). However, the yield of formic acid decreased by at least a factor of two in the absence of NO(x). The results of these experiments are used to elucidate a simplified gas-phase atmospheric degradation scheme for 1,3-dioxane and also provide valuable information on the atmospheric fate of the cyclic and linear alkoxy radicals produced in these and similar reactions. The available experimental data suggests that the relative importance of the competing pathways (reaction with O(2) and ring opening by C-C or C-O bond fission) is a strong function of the ring strain in the cycloalkoxy radicals.

An Investigation on the Principal Paths to Plasma Oxidation of Propylene and NO

Hydrocarbons plasma oxidation combined with fast selective catalytic reduction is a promising technology for treating the diesel exhausts with high sulfur content. In this study, propylene (C3H6) oxidation in a nonthermal plasma process and its effects on NO transition were investigated. The experimental results and the results from simulation based on a simplified model indicated that the binding reactions of O radicals ionizing from O2 with C3H6 are the trigger reactions, from which carbonyl (HCO) and ethyl radicals (C2H5) are produced and play crucial roles in C3H6 and NO oxidation. It was found that carbon monoxide (CO), carbon dioxide (CO2), formaldehyde (HCHO), acetaldehyde (CH3CHO), formic acid (HCOOH), etc. are the final oxidation products of C3H6 oxidation in the absence of NO. With the presence of NO, peroxy (CH3O2 and C2H5O2), and hydroperoxy radical (HO2) that come from C3H6 oxidation are able to oxidize NO to NO2 efficiently and, meanwhile, induce the reactions that would lead to the formatio...

NO x-assisted soot oxidation over K/CuCe catalyst

CeO 2 and CuO x -CeO 2 supported potassium catalysts were synthesized by wetness impregnation method. The catalysts were characterized by BET, NO-TPO, NO x -TPD and soot-TPO measurements. By the decoration of potassium and copper, the maximum soot combustion temperature of the ceria-based catalyst decreased to 338 and 379 °C in the presence and absence of NO under a loose contact mode, respectively. The pronouncedly enhanced NO oxidation ability by copper introduction and NO x storage capacity by potassium modification were especially important in the NO x -assisted soot oxidation reaction with the K/CuCe catalyst.

057 The role of cytochrome p450 metabolites as an endothelium-derived hyperpolarising factor in the regulation of vascular tone in vivo in the forearm vasculature of healthy and diabetic individuals

Background Epoxyeicosatrienoic acids are arachidonic-acid-derived products of cytochrome P450 (CYP450) epoxygenases. Endothelium-derived hyperpolarizing factor (EDHF) stimulates calcium dependent potassium channels by CYP450 metabolites that can be inhibited with fluconazole (FLU). The role of EDHF in impaired endothelial function remains undefined. We hypothesised a differential contribution of EDHF in diabetics (DM) compared to healthy subjects. Methods In 16 healthy and 14 DM subjects, we measured forearm blood flow (FBF) with venous occlusion strain gauge plethysmography at rest and after endothelium-dependent and -independent vasodilation with acetylcholine (7.5, 15, 30 μg/min) or bradykinin (100, 200, 400 ng/min) and sodium nitroprusside (1.6 and 3.2 μg/min), respectively. Measurements were repeated after NO blockade with LNG monomethyl arginine (L-NMMA, 8 μmol/min), CYP450 blockade with fluconazole (0.4–1.6 μmol/min) and combined NO and CYP450 blockade. Results L-NMMA reduced resting FBF by −1.75 mls/min (p Conclusions NO is the major contributor to resting vasodilator tone in healthy subjects, whereas both NO and hyperpolarisation via CYP450 metabolites contribute to resting tone in DM. However, in the absence of NO in healthy subjects CYP450 metabolites were observed to have an important contribution suggesting an upregulation of EDHF activity via CYP450 metabolites when there is a decreased NO bioavailability. CYP450 metabolites do not contribute to pharmacologically stimulated vasodilation in either DM or healthy subjects, but whether other EDHFs play a role needs to be studied.

N 2O decomposition over Fe-zeolites: Structure of the active sites and the origin of the distinct reactivity of Fe-ferrierite, Fe-ZSM-5, and Fe-beta. A combined periodic DFT and multispectral study

The N 2O decomposition over Fe-ferrierite, Fe-beta, and Fe-ZSM-5 has been recently studied [K. Jisa, J. Novakova, M. Schwarze, A. Vondrova, S. Sklenak, Z. Sobalik, J. Catal. 262 (2009) 27] and a superior activity of Fe-ferrierite with respect to Fe-beta and Fe-ZSM-5 has been shown. In this study, we investigated (1) plausible active sites for the N 2O decomposition over Fe-ferrierite and (2) the origin of the distinct reactivity of Fe-ferrierite, Fe-ZSM-5 and Fe-beta employing a combined theoretical (periodic DFT) and experimental (UV–vis–NIR spectroscopy, IR spectroscopy, 29Si MAS NMR spectroscopy and catalytic batch experiments) approach. We evidenced that two Fe(II) cations accommodated in two adjacent six-membered rings in the eight-membered ring channel ( β sites) of Fe-ferrierite (the calculated Fe–Fe distance is 7.4 Å) form the active site responsible for the superior activity of this catalyst in the N 2O decomposition in the absence of NO. Similar structures can be formed in Fe-beta. However, the probability of their formation is very low. For Fe-ZSM-5, the geometrical arrangement of the cationic positions is far from that in Fe-ferrierite and it is not suitable for the N 2O decomposition. Therefore, the predicted order of the activity of the Fe(II) exchanged zeolites agrees with our experimental findings and it is: Fe-ferrierite ≫ Fe-beta > Fe-ZSM-5. We further showed that the accommodation of divalent cations in rings forming cationic sites can lead to significant rearrangements of the local structures of the zeolite framework, and therefore, the precise structure of sites binding a divalent cation cannot be derived from results of X-ray diffraction experiments, but can be inferred from theoretical calculations.

Effects of adsorbed and gaseous NOx species on catalytic oxidation of diesel soot with MnOx–CeO2 mixed oxides

MnOx–CeO2, MnOx and CeO2 catalysts were synthesized by the sol–gel method. The structural, redox and adsorption properties of the individual and mixed oxides were investigated by X-ray diffraction (XRD), Brunauer–Emmett–Teller (BET), CO temperature-programmed reduction (TPR), NO temperature-programmed oxidation (TPO), NOx temperature-programmed desorption (TPD) and in situ diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS). The TPO tests were performed with the soot–catalyst mixture under loose contact conditions to evaluate the catalytic activity of the oxide catalysts for soot oxidation. The MnOx–CeO2 mixed oxide catalyst presents the lowest soot oxidation temperature among the catalysts investigated in the presence of NO and O2. The synergetic effect between manganese oxide and ceria restrains the growth of oxide crystallites, increases the specific surface area and improves the low-temperature redox property. Especially, the activity of MnOx–CeO2 mixed oxides for NO oxidation and its capacity for NO2 storage in the form of surface nitrates are greatly enhanced. Not only the NO2 released from decomposition of surface nitrates but also that formed by catalytic oxidation of gaseous or adsorbed NO on the catalyst is confirmed important for soot oxidation. It is found by the in situ DRIFTS tests with the soot–catalyst mixture that the generation of surface oxygen complexes (SOCs), such as carboxylic anhydrides, lactones, quinine, ceto-enol groups, ethers and phenols, occurs at about 100°C lower temperature with exposure to NO than in the absence of NO, which is an important step for soot oxidation.

A comparative study of the NH 3-SCR reactions over a Cu-zeolite and a Fe-zeolite catalyst

The NH 3-SCR (selective catalytic reduction) reactions were systematically investigated over a commercial copper zeolite catalyst in view of its application to the DeNO x aftertreatment of exhaust gases from light- and heavy-duty Diesel engines. Catalytic activity data were collected at high space velocities in both steady state and dynamic runs over the catalyst in the form of powder, in order to derive intrinsic kinetic information in a wide temperature range. Results were also compared to those obtained over a commercial iron zeolite catalyst under similar conditions. With respect to the iron-based catalyst, the copper zeolite system showed a higher ammonia storage capacity, a higher activity in the ammonia oxidation reaction and in the Standard SCR reaction, and its DeNO x activity was found less sensitive to the NO 2 feed content. As opposite to the iron zeolite, over the copper zeolite no inhibiting effect of ammonia on the Standard SCR reaction was observed, while formation of some N 2O was detected even in the absence of NO 2 in the gas feed mixture.

Thromboxane receptor-mediated vasomotion and cerebrocortical blood flow oscillations in NO-deficiency

Event Abstract Back to Event Thromboxane receptor-mediated vasomotion and cerebrocortical blood flow oscillations in NO-deficiency Gábor Lenzsér1, Béla Horváth1, András Iring1, Péter Hermán1, Katalin Komjáti1, Péter Sándor1 and Zoltán Benyó1* 1 Semmelweis University, Institute of Human Physiology and Clinical Experimental Research, Hungary The effect of the thromboxane-receptor agonist U-46619 on the development of vasomotion of middle cerebral arteries (MCAs) in vitro and cerebrocortical blood flow (CoBF)-oscillations in vivo was studied under physiological conditions and after NO synthase (NOS) blockade. CoBF was measured in the parietal cortex of anesthetized, spontaneously breathing adult male Wistar rats by laser Doppler (LD) flowmetry. The dominant frequency and the corresponding magnitude of the LD flux (LDF) oscillations were evaluated by Fourier-analysis before and after the administration of U-46619. In vitro experiments were performed in isolated MCA segments by isometric tension recording in a conventional myograph system. Under physiological conditions the administration of U-46619 (1 μg/kg i.v.) failed to change the LDF or induce LDF oscillations. After NOS blockade by NG-nitro-L-arginine methyl ester (L-NAME, 100 mg/kg i.v.) the LDF decreased and oscillations appeared with a dominant frequency of 0.144±0.023 Hz and a magnitude of 5.99±0.66 AU. Administration of U-46619 resulted in a significant (p<0.05) increase of the magnitude of the oscillation to 8.84±0.94 AU without changing the frequency (0.144±0.026 Hz) or the mean LDF. Similarly, in isolated MCA segments 1 μM U-46619 had no effect under physiological conditions but induced marked vasomotion in the presence of 100 μM L-NAME. Our results demonstrate that activation of the thromboxane-receptors with a low dose of U-46619, which has no major effect on the cerebrovascular tension or cerebrocortical blood flow under physiological conditions, evokes strong vasomotion and CoBF-oscillations in the absence of NO. Supported by NKTH OMFB-00770/2009, TÁMOP 4.2.2. - 08/1/KMR-2008-004, OTKA K62375 and an EFSD/Servier Grant Award. Conference: IBRO International Workshop 2010, Pécs, Hungary, 21 Jan - 23 Jan, 2010. Presentation Type: Poster Presentation Topic: Disorders of the nervous system Citation: Lenzsér G, Horváth B, Iring A, Hermán P, Komjáti K, Sándor P and Benyó Z (2010). Thromboxane receptor-mediated vasomotion and cerebrocortical blood flow oscillations in NO-deficiency. Front. Neurosci. Conference Abstract: IBRO International Workshop 2010. doi: 10.3389/conf.fnins.2010.10.00026 Copyright: The abstracts in this collection have not been subject to any Frontiers peer review or checks, and are not endorsed by Frontiers. They are made available through the Frontiers publishing platform as a service to conference organizers and presenters. The copyright in the individual abstracts is owned by the author of each abstract or his/her employer unless otherwise stated. Each abstract, as well as the collection of abstracts, are published under a Creative Commons CC-BY 4.0 (attribution) licence (https://creativecommons.org/licenses/by/4.0/) and may thus be reproduced, translated, adapted and be the subject of derivative works provided the authors and Frontiers are attributed. For Frontiers’ terms and conditions please see https://www.frontiersin.org/legal/terms-and-conditions. Received: 19 Apr 2010; Published Online: 19 Apr 2010. * Correspondence: Zoltán Benyó, Semmelweis University, Institute of Human Physiology and Clinical Experimental Research, Budapest, Hungary, zoltan.benyo@pharma.uni-heidelberg.de Login Required This action requires you to be registered with Frontiers and logged in. To register or login click here. Abstract Info Abstract The Authors in Frontiers Gábor Lenzsér Béla Horváth András Iring Péter Hermán Katalin Komjáti Péter Sándor Zoltán Benyó Google Gábor Lenzsér Béla Horváth András Iring Péter Hermán Katalin Komjáti Péter Sándor Zoltán Benyó Google Scholar Gábor Lenzsér Béla Horváth András Iring Péter Hermán Katalin Komjáti Péter Sándor Zoltán Benyó PubMed Gábor Lenzsér Béla Horváth András Iring Péter Hermán Katalin Komjáti Péter Sándor Zoltán Benyó Related Article in Frontiers Google Scholar PubMed Abstract Close Back to top Javascript is disabled. Please enable Javascript in your browser settings in order to see all the content on this page.

Yields of Glyoxal and Ring-Cleavage Co-Products from the OH Radical-Initiated Reactions of Naphthalene and Selected Alkylnaphthalenes

Naphthalene and alkylnaphthalenes are the most abundant polycyclic aromatic hydrocarbons present in ambient air and are transformed mainly by chemical reaction with hydroxyl (OH) radicals during daylight hours. To better understand the reaction mechanisms, we have quantified glyoxal from the OH radical-initiated reactions of naphthalene, 1-methylnaphthalene, 1,4-dimethylnaphthalene, acenaphthene, and acenaphthylene as a function of the NO(2) concentration and, for the naphthalene reaction, also in the absence of NO(2). Glyoxal was formed as a first-generation product from the naphthalene, 1-methylnaphthalene, 1,4-dimethylnaphthalene, and acenaphthene reactions, and its yields were independent of the NO(2) concentration over the ranges employed, being 5% in the presence of NO(2) and 3% in the absence of NO(2) from naphthalene; approximately 3% from 1-methylnaphthalene; approximately 2% from 1,4-dimethylnaphthalene; approximately 10-15% from acenaphthene; and <2% from acenaphthylene. Second-generation formation of glyoxal was evident in the 1-methylnaphthalene, 1,4-dimethylnaphthalene, and acenaphthene reactions. For the naphthalene reaction, our results suggest that the reactions of the OH-naphthalene adducts with NO(2) and O(2) both lead to glyoxal formation in similar yield. Simultaneous measurements of phthaldialdehyde from naphthalene, 2-acetylbenzaldehyde from 1-methylnaphthalene, and 1,2-diacetylbenzene from 1,4-dimethylnaphthalene suggest that these C(n-2)-dicarbonyls are coproducts to glyoxal.

Enhanced NH3 Selective Catalytic Reduction for NOx Abatement

Enhanced NO reduction efficiencies, close to those obtained under the conditions of fast selective catalytic reduction (SCR; see diagram), were achieved over commercial vanadium and iron-exchanged zeolite SCR catalysts at low temperatures (200–300 °C) in the absence of NO2 by reaction of NO with ammonia and an aqueous solution of ammonium nitrate.