scholarly journals Numerical studies of nitric oxide formation in nanosecond-pulsed discharge-stabilized flames of premixed methane/air

2015 ◽  
Vol 373 (2048) ◽  
pp. 20140331
Author(s):  
Moon Soo Bak ◽  
Mark A. Cappelli
Keyword(s):  
Nitric Oxide ◽  
Atomic Oxygen ◽  
Oh Radicals ◽  
Post Discharge ◽  
Nitric Oxide Formation ◽  
No Formation ◽  
Numerical Studies ◽  
Discharge Temperature ◽  
Discharge Simulation ◽  
Kinetics Of

A simulation is developed to investigate the kinetics of nitric oxide (NO) formation in premixed methane/air combustion stabilized by nanosecond-pulsed discharges. The simulation consists of two connected parts. The first part calculates the kinetics within the discharge while considering both plasma/combustion reactions and species diffusion, advection and thermal conduction to the surrounding flow. The second part calculates the kinetics of the overall flow after mixing the discharge flow with the surrounding flow to account for the effect that the discharge has on the overall kinetics. The simulation reveals that the discharge produces a significant amount of atomic oxygen (O) as a result of the high discharge temperature and dissociative quenching of excited state nitrogen by molecular oxygen. This atomic oxygen subsequently produces hydroxyl (OH) radicals. The fractions of these O and OH then undergo Zel’dovich reactions and are found to contribute to as much as 73% of the total NO that is produced. The post-discharge simulation shows that the NO survives within the flow once produced.

scholarly journals Both physical fitness and acute exercise regulate nitric oxide formation in healthy humans

1997 ◽  
Vol 82 (3) ◽  
pp. 760-764 ◽  
Author(s):  
Lennart Jungersten ◽  
Anneli Ambring ◽  
Björn Wall ◽  
Åke Wennmalm
Keyword(s):  
Nitric Oxide ◽  
Physical Exercise ◽  
Physical Fitness ◽  
Acute Exercise ◽  
Oxide Formation ◽  
Bicycle Ergometry ◽  
Healthy Humans ◽  
Nitric Oxide Formation ◽  
No Formation ◽  
Plasma Nitrate

Jungersten, Lennart, Anneli Ambring, Björn Wall, andÅke Wennmalm. Both physical fitness and acute exercise regulate nitric oxide formation in healthy humans. J. Appl. Physiol. 82(3): 760–764, 1997.—We analyzed nitrate, a major stable end product of nitric oxide (NO) metabolism in vivo in plasma and urine from groups of healthy subjects with different working capacities. Resting plasma nitrate was higher in athletic subjects than in nonathletic controls [45 ± 2 vs. 34 ± 2 (SE) μM; P < 0.01]. In other subjects, both the resting plasma nitrate level ( r = 0.53; P < 0.01) and the urinary excretion of nitrate at rest ( r = 0.46; P < 0.01) correlated to the subjects’ peak work rates, as determined by bicycle ergometry. Two hours of physical exercise elevated plasma nitrate by 18 ± 4 ( P < 0.01) and 16 ± 6% ( P < 0.01), respectively, in athletes and nonathletes, compared with resting nitrate before exercise. We conclude that physical fitness and formation of NO at rest are positively linked to each other. Furthermore, a single session of exercise elicits an acute elevation of NO formation. The observed positive relation between physical exercise and NO formation may help to explain the beneficial effects of physical exercise on cardiovascular health.

Inhibition of nitrovasodilators by pyocyanin and methylene blue is dissociated from nitric oxide formation

1994 ◽  
Vol 72 (7) ◽  
pp. 746-752 ◽  
Author(s):  
Jovan Bozinovski ◽  
James F. Brien ◽  
Gerald S. Marks ◽  
Kanji Nakatsu
Keyword(s):  
Nitric Oxide ◽  
Methylene Blue ◽  
Sodium Nitroprusside ◽  
Isosorbide Dinitrate ◽  
Rabbit Aorta ◽  
Aortic Ring ◽  
Organic Nitrates ◽  
No Production ◽  
Nitric Oxide Formation ◽  
No Formation

The phenazine pigment pyocyanin (Pyo), like methylene blue (MB), inhibits vascular relaxation induced by organic nitrates. These nitrovasodilators are pro-drugs that have in common the ability to generate nitric oxide (NO). In this study, we characterized responses of rabbit isolated aortic ring to 3-morpholinosydnonimine (SIN-1), S-nitroso-N-acetylpenicillamine (SNAP), sodium nitroprusside, glyceryl trinitrate (GTN), and isosorbide dinitrate in the presence and absence of 10 μM Pyo. We also examined the effect of Pyo (1 and 10 μM) and MB (1 and 10 μM) on vasorelaxation induced by authentic NO, and finally we tested the effects of Pyo and MB on the tissue-independent formation of NO from SIN-1, SNAP, and sodium nitroprusside, using die chemiluminescence – headspace gas method. Pyo (10 μM) surmountably inhibited aortic responses to GTN, isosorbide dinitrate, SIN-1, and SNAP with a characteristic rightward shift of the dose–response curve; the apparent EC50 of these drugs for relaxation of phenylephrine-contracted aorta was increased 18-, 4-, 13-, and 15-fold, respectively. Pyo (1 and 10 μM) and MB (10 μM) inhibited NO-induced vasorelaxation at the EC50 of NO by 35, 72, and 56%. In contrast, Pyo did not inhibit sodium nitroprusside induced vasodilation. For a 10-min incubation, 10 μM Pyo or MB increased NO production from SNAP 1.8- and 2.9-fold, respectively, and increased NO production from SIN-1 by 3.8- and 7.1-fold, respectively. Neither Pyo nor MB enhanced NO formation from sodium nitroprusside. These data indicate that Pyo and MB inhibit nitrovasodilator-induced relaxation of aortic ring by interfering with the action of NO, subsequent to its formation.Key words: pyocyanin, nitric oxide, methylene blue, nitrovasodilators, rabbit aorta.

Protein kinase βII in Zucker obese rats compromises oxygen and flow-mediated regulation of nitric oxide formation

2004 ◽  
Vol 286 (2) ◽  
pp. H492-H497 ◽  
Author(s):  
H. Glenn Bohlen
Keyword(s):  
Nitric Oxide ◽  
Blood Flow ◽  
Flow Velocity ◽  
Oxygen Depletion ◽  
Oxygen Availability ◽  
Zucker Rats ◽  
No Production ◽  
Nitric Oxide Formation ◽  
No Formation ◽  
Obese Rats

In severe obesity, microvascular endothelial regulation of nitric oxide (NO) formation is compromised in response to muscarinic stimulation, and major arteries have suppressed flow-mediated dilation. Because normal microvessels are highly dependent on flow-mediated stimulation of NO generation and are responsive to intra- and extravascular oxygen availability, they are likely a major site of impaired endothelial regulation. This study evaluated the blood flow and oxygen-dependent aspects of intestinal microvascular regulation and NO production in Zucker obese rats just before the onset of hyperglycemia. Ruboxistaurin (LY-333531) was used to inhibit PKC-βII to determine whether flow or oxygen-related NO regulation was improved. Blood flow velocity was increased by forcing arterioles to perfuse ∼50% larger tissue areas by occlusion of nearby arterioles, and oxygen tension in the bath was lowered to create a modest oxygen depletion. When compared with lean Zucker rats, the periarteriolar NO concentration ([NO]) for obese rats was ∼30% below normal. At elevated shear rates, the [NO] for arterioles of obese animals was 20–30% below those in the arterioles of lean rats, and the NO response to decreased oxygen was about half normal in obese rats. All of these regulatory problems were essentially corrected in obese rats by PKC blockade with only minor changes in the microvascular behavior in lean rats. Therefore, activation of PKC-βII in endothelial cells during obesity suppressed NO regulation both at rest and in response to increased flow velocity and decreased oxygen availability.

Development and Application of a Transported PDF Method on Unstructured Three-Dimensional Grids for the Prediction of Nitric Oxides

2013 ◽  
Author(s):  
Andreas Fiolitakis ◽  
Peter Ess ◽  
Peter Gerlinger ◽  
Manfred Aigner
Keyword(s):  
Nitric Oxide ◽  
Turbulent Combustion ◽  
Flame Structure ◽  
Hybrid Approach ◽  
Three Dimensional ◽  
Navier Stokes ◽  
Nitric Oxides ◽  
Nitric Oxide Formation ◽  
No Formation ◽  
German Aerospace

The present work explores the capability of the transported PDF (probability density function) method to predict nitric oxide (NO) formation in turbulent combustion. To this end a hybrid finite-volume/Lagrangian Monte-Carlo method is implemented into the THETA code of the German Aerospace Center (DLR). In this hybrid approach the transported PDF method governs the evolution of the thermochemical variables, whereas the flow field evolution is computed with a RANS (Reynolds-Averaged Navier Stokes) method. The method is used to compute a turbulent hydrogen-air flame and a methane-air flame and computational results are compared to experimental data. In order to assess the advantages of the transported PDF method, the flame computations are repeated with the “laminar chemistry” approach as well as with an “assumed PDF” method, which are both computationally cheaper. The present study reveals that the transported PDF method provides the highest accuracy in predicting the overall flame structure and nitric oxide formation.

NAMPT single-nucleotide polymorphism rs1319501 and visfatin/NAMPT affect nitric oxide formation, sFlt-1 and antihypertensive therapy response in preeclampsia

2021 ◽  
Author(s):  
Daniela A Pereira ◽  
Valeria C Sandrim ◽  
Ana C Palei ◽  
Lorena M Amaral ◽  
Vanessa A Belo ◽  
...  
Keyword(s):  
Nitric Oxide ◽  
Antihypertensive Therapy ◽  
Therapy Response ◽  
Women Patients ◽  
Nucleotide Polymorphism ◽  
Oxide Formation ◽  
Single Nucleotide ◽  
Functional Snps ◽  
Nitric Oxide Formation ◽  
No Formation

Aim: We examined the relationships between visfatin/NAMPT and nitrite concentrations (a marker of nitric oxide [NO] formation) or sFlt-1 levels in 205 patients with preeclampsia (PE) responsive or nonresponsive to antihypertensive therapy, and whether NAMPT SNPs rs1319501 and rs3801266 affect nitrite concentrations in PE and 206 healthy pregnant women. Patients & methods: Circulating visfatin/NAMPT and sFlt-1 levels were measured by ELISA, and nitrite concentrations by using an ozone-based chemiluminescence assay. Results: In nonresponsive PE patients, visfatin/NAMPT levels were inversely related to nitrite concentrations and positively related to sFlt-1 levels. NAMPT SNP rs1319501 affected nitrite concentrations in nonresponsive PE patients and was tightly linked with NAMPT functional SNPs in Europeans. Conclusion: NAMPT SNP rs1319501 and visfatin/NAMPT affect NO formation, sFlt-1 levels and antihypertensive therapy response in PE.

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