Papers by Keyword: Nitric Oxide (NO)

Abstract: A Nafion/phosphotungstic heteropolyacid/polypyrrole modified glassy carbon electrode (Nf/PW₁₂/PPY/GCE) was prepared in this paper. The electrochemical behaviours of nitric oxide at the Nf/PW₁₂/PPY/GCE were investigated by cyclic voltammetry. The experimental results indicated that the phosphotungstic heteropolyacid doped in polypyrrole film possessed obvious catalysis for the electroxidation of nitric oxide. In 0.1mol/L sulfuric acid, the anodic peak current of nitric oxide at the sensors linearly increased with nitric oxide concentration over the range of 1.0×10^-7～2.5×10^-5 mol/L with a detection limit of 3.0×10^-8 mol/L. The Nafion layer modified on the surface of electrocatalyst could effectively eliminate the inferences from common species in biological samples such as ascorbate, uric acid and nitrite. The presented methods of determing nitric oxide exhibited high sensitivity and good reproducibility.

Abstract: Nitric oxide (NO) reduction through coal, biomass and their blend reburning is conducted on a drop tube furnace experimental system and it is proved to be feasible of using the coal-biomass blend as the reburning fuel. For a high NO reduction efficiency, the excess air ratio in the reburning zone should be less than 0.9 and the reaction temperature is required to be higher than 1373K. 50-60% of the biomass percentage in the blend is enough for an acceptable efficiency. At the same time, for a thorough NO reduction process, the reburning fuel fraction and the residence time in the reburning zone must be guaranteed about 20% and 0.6-0.8s, respectively. Also, when the initial NO concentration is excess 600ppm, the efficiency is varied little at different NO concentrations.

Abstract: The effects of nitric oxide (NO) in protecting maize (Zea mays) roots against cadmium (Cd) toxicity were investigated. Maize seedlings pretreated for 24 h with 10-40 µM sodium nitroprusside (SNP), an NO donor, and subsequently exposed to 5 µM Cd for 24 h exhibited significantly greater root elongation as compared with the plants without SNP pretreatment. The pretreatment with 20 µM SNP alleviated Cd toxicity most obviously. SNP reduced Cd-induced accumulation of hydrogen peroxide (H2O2) and malonodialdehyde (MDA), which indicated NO alleviated Cd-induced oxidative damage. Cd treatment resulted in an upregulation of activities of superoxide dismutase (SOD), peroxidase (POD) and ascorbate peroxidase (APX) and the contents of glutathione (GSH) and ascorbate (ASC). Though SNP suppresses activities of POD, SOD and APX, it increases the production of non-enzymic antioxidants including glutathione (GSH) and ascorbate (ASC). The protective effect of SNP on Cd toxicity can be reversed by 2-(4-carboxy-2-phenyl)-4,4,5,5 -tetramethylimidazoline-1-oxyl-3-oxide (cPTIO), a NO scavenger, suggesting that the protective effect of SNP is attributable to NO released. These results suggest that NO plays an important role in protecting the plant against Cd-induced oxidative damage.

Abstract: Abscisic acid (ABA) and sodium nitroprusside (SNP) treatment significantly increased chilling tolerance in maize seedlings. ABA in combination with nitric oxide (NO) donor SNP further enhanced the ABA-induced chilling tolerance. But the addition of NO scavenger 2-phenyl-4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide (PTIO) nullified the increasing effect of SNP on chilling tolerance. In addition, the combination of ABA and PTIO decreased the ABA-induced chilling tolerance. Measurement of activities of superoxide dismutase (SOD) and catalase (CAT), hydrogen peroxide (H2O2) content and the level of lipid peroxidation (in terms of malondialdehyde) indicated that chilling stress induced an oxidative stress in maize seedlings. ABA treatment enabled maize seedlings to maintain higher SOD and CAT activities and lower level of H2O2 and lipid peroxidation under chilling stress. ABA in combination with SNP further enhanced the ABA-induced increase in SOD and CAT activities and lowered the chilling stress-induced lipid peroxidation in the ABA-treated seedlings. But the addition of PTIO scavenged the increasing effect of SNP. In addition, the combination of ABA and PTIO had a contrary effect with that of ABA and SNP. These results suggest that the ABA-induced chilling tolerance is mediated by NO, NO is involved in ABA-induced chilling tolerance by increasing activities of antioxidant enzymes and reduced endogenous H2O2 accumulation.

Abstract: In the study, the gas exchange parameters and chlorophyll contents of the leaves of Taxus chinensis var. mairei exposed to exogenous nitric oxide (NO) were determined. The seedlings were treated with sodium nitroprusside (SNP), a NO donor, at 5 different concentrations ranging from 0 mM to 1 mM. The experiment was conducted under controlled conditions in laboratory. The result showed that the 1 mM SNP increased the net photosynthetic rate (PN) of Taxus chinensis var. mairei slightly; however, other SNP treatments decreased PN. The water use efficiency (WUE) was increased by exogenous NO, while the stomata conductance (Gs) and the transpiration rate (E) were decreased. The concentrations of chlorophyll a, chlorophyll b, carotenoid and total chlorophyll exhibited 0.1 mM> 0.01 mM> 1 mM > 0 mM > 0.5 mM after 10 days of SNP treatments. The experiment proved that at suitable concentrations of exogenous NO signals increased the photosynthesis, and suggested that the SNP treatment might promote the growth of the Taxus chinensis var. mairei seedlings.

Abstract: Catalytic oxidation of NO with O2 over Pt/-Al2O3 and La0.8Sr0.2MnO3 was conducted with a tubular reactor in range of space time 0.090-0.720 second, inlet NO concentration 0.03-0.2 vol%, O2 concentration 2-10 vol% and at 473 K. Under the conditions of 0.720 s space time, 0.05 vol% NO and 5 vol% O2 concentrations, the steady-state conversion of NO oxidation over Pt/-Al2O3 and La0.8Sr0.2MnO3 reached 22.4 and 90.5 %, respectively. A kinetic model consisting of 12 elementary reactions fits the experimental data adequately, indicated that the rate-limiting step of NO oxidation over Pt/-Al2O3 was the reaction between gaseous NO with dissociately adsorbed O, and over La0.8Sr0.2MnO3 was the desorption of product NO2.

Abstract: Role of nitric oxide(NO) and hydrogen peroxide(H₂O₂) in eATP-inhibited reduction of in vitro pollen germination and tube growth of Paulownia tomentosa Steud. were studied. Results showed that exposure of the pollen to a series of eATP (0.2, 0.4, 0.6, 0.8, 1.0 mM) concentration for 3h resulted in not only the reduction of pollen germination but also the reduction of tube growth. Also, NOS inhibitor NG-nitro-L-Arg-methyl eater (L-NAME ), NO scavenger 2-(4-carboxyphenyl)-4,4,5,5-tetramethylimidazoline-1-oxyl-3- oxide(c-PTIO) and two scavengers of H₂O₂, ascorbic acid (ASC) and catalase (CAT) not only largely prevented eATP-inhibited pollen germination but also tube growth. These results indicated that NO and H₂O₂ are involved in eATP inhibited pollen germination and tube growth.

Abstract: The L-ascorbic acid can reduce the nitrite to nitric oxide, but the elevated nitrite-to-L-ascorbic acid ratio predisposes to the formation of potentially carcinogenic N-nitroso compound. We study the chemicals which nitrite reacted to L-ascorbic acid with an elevated L-ascorbic acid-to- nitrite ratio in the solution. The products, when the nitrite reacted with L-ascorbic in the solution, were nitric oxide (NO), dinitrogen monoxide (N₂O) and nitrogen gas (N₂). We give advice that it maybe useful to understand the products which nitrite reacts with L-ascorbic acid in the human beings and other organisms.

Abstract: Taxus chinensis var. mairei was used as test material, exogenous nitric oxide (NO) fumigation treatment with different concentration (0, 0.01, 0.1, 0.5 or 1 mM) of sodium nitrop russide (SNP), a donor for exogenous NO, was used to study the effects of NO on the active oxygen metabolism index of superoxide dismutase (SOD), catalase (CAT), ascorbate peroxidase (APX), peroxidase (POD), Hydrogen peroxide (H2O2) and malondialdehyde (MDA) in Taxus chinensis var. mairei. The results showed that low concentration of exogenous NO treatment increased the activities of the protective enzyme, such as SOD, CAT, POD and APX of Taxus chinensis var. mairei leaves, reduced the content of H2O2, and inhibit the increase of MDA in the first three days. NO fumigation treatment enhanced the antioxidant ability of Taxus chinensis var. mairei, prevented lipid membrane peroxidation.

Abstract: In the study, the gas exchange parameters and chlorophyll contents in the needles of Pinus koraiensis Sieb. et Zucc. exposed to exogenous nitric oxide (NO) were determined. The Pinus koraiensis Sieb. et Zucc. seedlings were treated with sodium nitroprusside (SNP), a NO donor, at 5 different concentrations ranging from 0 mM to 1 mM. The result showed that at different concentrations exogenous NO had different effects on the photosynthetic parameters and photosynthetic pigments. The content of chlorophyll was maximal in the treatment with SNP at 0.01 mM. At low concentrations (0.1 mM) SNP significantly increased the photosynthetic rate (PN) and decreased the Respiration rate (RD) and Compensation irradiance (IC) of the needles (p<0.05). The experiment proved that at low concentrations exogenous NO signals increased the photosynthesis of Pinus koraiensis Sieb. et Zucc. seedlings. The present results suggested that the lower concentrations SNP might decrease the level of reactive oxygen species (ROS) and promote the growth of the Pinus koraiensis Sieb. et Zucc.