hydrogen peroxide

摘要： The breaking of dormancy mediated by reac-tive nitrogen species(RNS)is related to the accumulation of reactive oxygen species(ROS)in germinating embryos but the underlying mechanism is unclear.The objectives of this study were:(1)to explore the relationship between RNS-mediated dormancy release and ROS accumulation in germinating embryos of Sorbus pohuashanensis;and,(2)to investigate the relationships among germination time,ROS metabolism,and endogenous hormone synthesis.We studied the effects of exogenous nitric oxide(NO)donor sodium nitroprusside(SNP),the NO scavenger(4-carboxyphenyl)-4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide(PTIO),abscisic acid(ABA),the exogenous ethylene donor ethrel,and the ethylene receptor inhibitor 2,5-norbornadien(NBD)on embryo germination and seedling growth.Embryos were released from dormancy by pretreatment with NO or ethylene, which was related to increased ethylene biosyn-thesis and decreased ABA levels. Breaking of dormancy by SNP was related to increased levels of ethylene, hydrogen peroxide, and glutathione, increased activities of superoxide dismutase and glutathione peroxidase, and decreased levels of ABA, superoxide anions, and malondialdehyde. These effects of nitric oxide were especially significant in seedling hypocotyls and radicles. These results demonstrate that NO can break S. pohuashanensis embryo dormancy by induc-ing ethylene biosynthesis, and that this signalling pathway is closely related to ROS accumulation and the antioxidant defence response.

摘要： Electrocatalytic oxygen reduction reaction (ORR) via two-electron pathway is a promising approach to decentralized and on-site hydrogen peroxide (H_(2)O_(2)) production beyond the traditional anthraquinone process.In recent years,electrochemical H_(2)O_(2) production in acidic media has attracted increasing attention owing to its stronger oxidizing capacity,superior stability,and higher compatibility with various applications.Here,recent advances of H_(2)O_(2) electrosynthesis in acidic media are summarized.Specifically,fundamental aspects of two-electron ORR mechanism are firstly presented with an emphasis on the pH effect on catalytic performance.Major categories of promising electrocatalysts are then reviewed,including noble-metal-based materials,non-noble-metal single-atom catalysts,non-noblemetal compounds,and metal-free carbon-based materials.The innovative development of electrochemical devices and in situ/on-site application of electrogenerated H_(2)O_(2) are also highlighted to bridge the gap between laboratory-scale fundamental research and practically relevant H_(2)O_(2) electrosynthesis.Finally,critical perspectives on present challenges and promising opportunities for future research are provided.

摘要： BACKGROUND Despite overt insulin resistance,adipocytes of genetically obese Zucker rats accumulate the excess of calorie intake in the form of lipids.AIM To investigate whether factors can replace or reinforce insulin lipogenic action by exploring glucose uptake activation by hydrogen peroxide,since it is produced by monoamine oxidase(MAO)and semicarbazide-sensitive amine oxidase(SSAO)in adipocytes.METHODS 3H-2-deoxyglucose uptake(2-DG)was determined in adipocytes from obese and lean rats in response to insulin or MAO and SSAO substrates such as tyramine and benzylamine.14C-tyramine oxidation and binding of imidazolinic radioligands[3H-Idazoxan,3H-(2-benzofuranyl)-2-imidazoline]were studied in adipocytes,the liver,and muscle.The influence of in vivo administration of tyramine+vanadium on glucose handling was assessed in lean and obese rats.RESULTS 2-DG uptake and lipogenesis stimulation by insulin were dampened in adipocytes from obese rats,when compared to their lean littermates.Tyramine and benzylamine activation of hexose uptake was vanadate-dependent and was also limited,while MAO was increased and SSAO decreased.These changes were adipocyte-specific and accompanied by a greater number of imidazoline I2 binding sites in the obese rat,when compared to the lean.In vitro,tyramine precluded the binding to I2 sites,while in vivo,its administration together with vanadium lowered fasting plasma levels of glucose and triacylglycerols in obese CONCLUSION The adipocytes from obese Zucker rats exhibit increased MAO activity and imidazoline binding site number.However,probably as a consequence of SSAO down-regulation,the glucose transport stimulation by tyramine is decreased as much as that of insulin in these insulin-resistant adipocytes.The adipocyte amine oxidases deserve more studies with respect to their putative contribution to the management of glucose and lipid handling.

摘要： Photocatalytic production of hydrogen peroxide(H_(2)O_(2))has attracted much attentions as a promising method for sustainable solar fuel.Here,we demonstrate that trace water can drastically boost highefficiency photocatalytic production of H_(2)O_(2) with a record-high concentration of 113 mmol L^(-1) using alkali-assisted C_(3)N_(4) as photocatalyst in water/alcohol mixture solvents.By electron paramagnetic resonance(EPR)measurement,the radical species generated during the photocatalytic process of H_(2)O_(2) are identified.We propose alcohol is used to provide and stabilize-OOH radicals through hydrogen bond,while trace water could trigger photocatalytic production of H_(2)O_(2) via providing and transferring indispensable free protons to completely consume OOH radicals,which breaks the reaction balance of-OOH radical generation from alcohol.Thus-OOH radicals could be supplied by alcohol continuously to serve as a reservoir for high-efficiency production of H_(2)O_(2).These results pave the way towards photocatalytic method on semiconductor catalysts as an outstanding approach for production of hydrogen peroxide.

摘要： Objective:To investigate antioxidant potential of pentoxifylline on spermatozoa of small ruminants including rams and bucks.Methods:The levels of hydrogen peroxide(H2O2)production in ram and buck spermatozoa incubated with 0(control),4 and 8 mM of pentoxifylline were measured after 45-min incubation.Then,the motility parameters of ram and buck spermatozoa incubated with 0(control),1 mM of H2O2,1 mM of H2O2 plus 4 mM of pentoxifylline,and 1 mM of H2O2 plus 8 mM of pentoxifylline were analysed.H2O2 was estimated using a fluorometric assay and spermatozoa motility characteristics were analyzed using computer aided sperm analyzer.Results:Pentoxifylline significantly decreased the levels of H2O2 produced from both ram and buck spermatozoa(P<0.05),and significant lower rates of H2O2 formation were noted when 8 mM of pentoxifylline was added(P<0.05).The values of all sperm motility parameters for the two species significantly decreased after incubation with H2O2(P<0.05).In contrast,when the spermatozoa were incubated with both H2O2 and two concentrations of pentoxifylline,the motility values rose significantly compared to those incubated with H2O2 alone(P<0.05).For both ram and buck sperm samples,the rapid and static subpopulation motility parameters were the most affected categories by pentoxifylline addition compared to the medium and slow categories.Conclusions:Pentoxifylline possesses an antioxidant capacity proved by its ability of reducing H2O2 levels as well as by increasing motility values of stressed spermatozoa.Therefore,pentoxifylline could be recommended as antioxidant additive for spermatozoa of small ruminants under stress conditions.

摘要： The Electro-Fenton(EF)process is one of the promising advanced oxidation processes(AOPs)for environmental remediation.The H_(2)O_(2) yield of EF process largely determines its performance on organic pollutants degradation.Conventional Pd-catalytic EF process generates H_(2)O_(2) via the combination reaction of anodic O_(2) and cathodic H;.However,the relatively expensive catalyst limits its application.Herein,a hybrid Pd/activated carbon(Pd/AC)-stainless steel mesh(SS)cathode(PACSS)was proposed,which enables more efficie nt H_(2)O_(2)generation.It utilizes AC,the support of Pd catalyst,as part of cathode for H_(2)O_(2) generation via 2-electron anodic O_(2) reduction,and SS serve as a current distributor.Moreover,H_(2)O_(2) could be catalytically decomposed upon AC to generate highly reactive·OH,which avoids the use of Fe;.Compared with conventional Pd catalyst,H_(2)O_(2) concentration obtained by PACSS cathode is248.2%higher,the O_(2)utilization efficiency was also increased from 3.2%to 10.8%.Within 50 min,26.3%,72.5%,and 94.0%H_(2)O_(2) was decomposed by Pd,AC,and Pd/AC.Fluorescence detection results implied that Pd/AC is effective upon H_(2)O_(2) activation for·OH generation.Finally,iron-free EF process enabled by PACSS cathode was examined to be effective for reactive blue 19(RB19)degradation.After continuous running for 10 cycles(500 min),the PACSS cathode was still stable for H_(2)O_(2)generation,H_(2)O_(2)activation,and RB19 degradation,showing its potential application for organic pollutants degradation without increase in the running cost.

摘要： Basic organic chemicals and high value–added products are mainly produced by hydrocarbon nitridation and oxidation.However,several drawbacks limit the application of the traditional oxidation and nitridation technologies in the future,such as complex processes,poor intrinsic safety,low atom utilization,and serious environmental pollution.The green nitridation and oxidation technologies are urgently needed.Hydrogen peroxide,a well–known green oxidant,is widely used in green hydrocarbon oxidation and nitridation.But its industrial production in China adopts fixed–bed technology,which is fall behind slurry–bed technology adopted by advanced foreign chemical companies,limiting the development of hydrogen peroxide industry and green hydrocarbon nitridation or oxidation industry.This article reviews the industrial production technologies of hydrogen peroxide and basic organic chemicals such as caprolactam,aniline,propene oxide,epichlorohydrin,phenol,and benzenediol,especially introduces the green production technologies of basic organic chemicals related with H_(2)O_(2).The article also emphasis on the efforts of Chinese researchers in developing its own slurry–bed technology of hydrogen peroxide production,and corresponding green hydrocarbon nitridation or oxidation technologies with hydrogen peroxide.Compared with traditional nitridation or oxidation technologies,green production technologies of caprolactam,propene oxide,epichlorohydrin,and benzenediol with hydrogen peroxide promote the nitrogen atom utilization from 60%to near 100%and the carbon atom utilization from 80%to near 100%.The waste emissions and environmental investments are reduced dramatically.Technological blockade against the green chemical industry of China are partially broken down,and technological upgrade in the chemical industry of China is guaranteed.

摘要： Hydrogen Peroxide vapour is becoming more popular to use as a method of decontamination, particularly for medical equipment and enclosures. It is highly effective in terms of microbiological kill rates and has a variety of uses in healthcare. Although it is environmentally acceptable as it spontaneously decomposes into water and oxygen, concentration of hydrogen peroxide in the air needs to be monitored and controlled. A method of calibrating hydrogen peroxide vapor sensors is described which is based on the concentration of hydrogen peroxide in saturated vapour over a solution in water at a defined temperature. The saturated vapour is generated by bubbling dry air into a solution of hydrogen peroxide at a defined concentration and temperature. A vapour at a concentration of 0.7 ppm was produced and used to successfully calibrate a hydrogen peroxide sensor.

摘要： Three biosorbents were prepared from Watermelon Rind (WMR) using microwave assisted procedure and then characterized using physiochemical techniques (pH, bulk density, volatile matter, surface area, ash content and moisture content). Physiochemical characterization of the synthesized biosorbents was done in order to evaluate their adsorption potentials. Accordingly, results obtained from the experiments conducted revealed the following trend: pH: Water Melon Rind treated with Sodium hydroxide (NaWMR) 8.5 > Water Melon Rind treated with Hydrogen peroxide (HP-WMR) 8.1 > Water Melon Rind treated with Distilled water (DWMR) 6.4 > Untreated Water Melon Rind (UWMR) 5.4, which suggest that NaWMR and HP-WMR possess suitable pH values for the uptake of cationic species within aqueous systems. Surface Area: analysis: UWMR (21.4 m2/g), DWMR (35.8 m2/g), NaWMR (40.6 m2/g) and HP-WMR (61.4 m2/g). This means that HP-WMR has a larger surface area and could be a preferred candidate for adsorption processes. The results obtained from this study suggest that chemical modification of Water Melon Rind (WMR) with either distilled water Sodium Hydroxide or Hydrogen peroxide by means of microwave irradiation enhances physiochemical properties which could boost the adsorption capacity of Water Melon Rind. Thus, the outcome shows that all the three synthesized biosorbents;DWMR, NaWMR and HP-WMR possess the characteristics of a good adsorbent. Accordingly, they can be applied to wastewater treatment process.

摘要： In this comprehensive evidence-based analysis of ulcerative colitis(UC),a causal role is identified for colonic epithelial hydrogen peroxide(H_(2)O_(2))in both the pathogenesis and relapse of this debilitating inflammatory bowel disease.Studies have shown that H_(2)O_(2) production is significantly increased in the non-inflamed colonic epithelium of individuals with UC.H_(2)O_(2) is a powerful neutrophilic chemo-tactic agent that can diffuse through colonic epithelial cell membranes creating an interstitial chemotactic molecular“trail”that attracts adjacent intra-vascular neutrophils into the colonic epithelium leading to mucosal inflammation and UC.A novel therapy aimed at removing the inappropriate H_(2)O_(2) mediated chemotactic signal has been highly effective in achieving complete histologic resolution of colitis in patients experiencing refractory disease with at least one(biopsy-proven)histologic remission lasting 14 years to date.The evidence implies that therapeutic intervention to prevent the re-establishment of a pathologic H_(2)O_(2) mediated chemotactic signaling gradient will indefinitely preclude neutrophilic migration into the colonic epithelium constituting a functional cure for this disease.Cumulative data indicate that individuals with UC have normal immune systems and current treatment guidelines calling for the suppression of the immune response based on the belief that UC is caused by an underlying immune dysfunction are not supported by the evidence and may cause serious adverse effects.It is the aim of this paper to present experimental and clinical evidence that identifies H_(2)O_(2) produced by the colonic epithelium as the causal agent in the pathogenesis of UC.A detailed explanation of a novel therapeutic intervention to normalize colonic H_(2)O_(2),its rationale,components,and formulation is also provided.