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Sample records for peroxide h2o2 catalyzes

  1. Sailuotong Prevents Hydrogen Peroxide (H2O2-Induced Injury in EA.hy926 Cells

    Directory of Open Access Journals (Sweden)

    Sai Wang Seto

    2017-01-01

    Full Text Available Sailuotong (SLT is a standardised three-herb formulation consisting of Panax ginseng, Ginkgo biloba, and Crocus sativus designed for the management of vascular dementia. While the latest clinical trials have demonstrated beneficial effects of SLT in vascular dementia, the underlying cellular mechanisms have not been fully explored. The aim of this study was to assess the ability and mechanisms of SLT to act against hydrogen peroxide (H2O2-induced oxidative damage in cultured human vascular endothelial cells (EAhy926. SLT (1–50 µg/mL significantly suppressed the H2O2-induced cell death and abolished the H2O2-induced reactive oxygen species (ROS generation in a concentration-dependent manner. Similarly, H2O2 (0.5 mM; 24 h caused a ~2-fold increase in lactate dehydrogenase (LDH release from the EA.hy926 cells which were significantly suppressed by SLT (1–50 µg/mL in a concentration-dependent manner. Incubation of SLT (50 µg/mL increased superoxide dismutase (SOD activity and suppressed the H2O2-enhanced Bax/Bcl-2 ratio and cleaved caspase-3 expression. In conclusion, our results suggest that SLT protects EA.hy916 cells against H2O2-mediated injury via direct reduction of intracellular ROS generation and an increase in SOD activity. These protective effects are closely associated with the inhibition of the apoptotic death cascade via the suppression of caspase-3 activation and reduction of Bax/Bcl-2 ratio, thereby indicating a potential mechanism of action for the clinical effects observed.

  2. A Facile, Nonreactive Hydrogen Peroxide (H2O2) Detection Method Enabled by Ion Chromatography with UV Detector.

    Science.gov (United States)

    Song, Mingrui; Wang, Junli; Chen, Baiyang; Wang, Lei

    2017-11-07

    Hydrogen peroxide (H 2 O 2 ) is ubiquitous in the natural environment, and it is now widely used for pollutant control in water and wastewater treatment processes. However, current analytical methods for H 2 O 2 inevitably require reactions between H 2 O 2 and other reactants to yield signals and are thus likely subjective to the interferences of coexisting colored, oxidative, and reductive compounds. In order to overcome these barriers, we herein for the first time propose to analyze H 2 O 2 by ion chromatography (IC) using an ultraviolet (UV) detector. The proposal is based on two principles: first, that H 2 O 2 can deprotonate to hydroperoxyl ion (HO 2 - ) when eluent pH is higher than the acid-dissociation coefficient of H 2 O 2 (pK a = 11.6); and second, that after separation from other compounds via IC column, H 2 O 2 can be quantified by a UV detector. Under favorable operating conditions, this method has successfully achieved acceptable recoveries (>91%) of H 2 O 2 dosed to ultrapure and natural waters, a calibration curve with R 2 > 0.99 for a wide range of H 2 O 2 concentrations from 0.1 to 50 mg/L and a method detection limit of 0.027 mg/L. In addition, this approach was shown to be capable of distinguishing H 2 O 2 from anions (e.g., fluoride and chloride) and organics (e.g., glycolate) and monochloramine, suggesting that it is insensitive to many neighboring compounds as long as they do not react quickly with H 2 O 2 . Hence, this study proves the combination of IC and UV detector a facile and reliable method for H 2 O 2 measurement.

  3. [Effect of Residual Hydrogen Peroxide on Hydrolysis Acidification of Sludge Pretreated by Microwave -H2O2-Alkaline Process].

    Science.gov (United States)

    Jia, Rui-lai; Liu, Ji-bao; Wei, Yuan-song; Cai, Xing

    2015-10-01

    Previous studies have found that in the hydrolysis acidification process, sludge after microwave -H2O2-alkaline (MW-H2O2-OH, pH = 10) pretreatment had an acid production lag due to the residual hydrogen peroxide. In this study, effects of residual hydrogen peroxide after MW-H2O2-OH (pH = 10 or pH = 11) pretreatment on the sludge hydrolysis acidification were investigated through batch experiments. Our results showed that catalase had a higher catalytic efficiency than manganese dioxide for hydrogen peroxide, which could completely degraded hydrogen peroxide within 10 min. During the 8 d of hydrolysis acidification time, both SCOD concentrations and the total VFAs concentrations of four groups were firstly increased and then decreased. The optimized hydrolysis times were 0.5 d for four groups, and the optimized hydrolysis acidification times were 3 d for MW-H2O2-OH (pH = 10) group, MW-H2O2-OH (pH = 10) + catalase group and MW-H2O2-OH (pH = 11) + catalase group. The optimized hydrolysis acidification time for MW-H2O2-OH (pH = 11) group was 4 d. Residual hydrogen peroxide inhibited acid production for sludge after MW-H2O2-OH (pH = 10) pretreatment, resulting in a lag in acidification stage. Compared with MW-H2O2-OH ( pH = 10) pretreatment, MW-H2O2-OH (pH = 11 ) pretreatment released more SCOD by 19.29% and more organic matters, which resulted in the increase of total VFAs production significantly by 84.80% at 5 d of hydrolysis acidification time and MW-H2O2-OH (pH = 11) group could shorten the lag time slightly. Dosing catalase (100 mg x -L(-1)) after the MW-H2O2-OH (pH = 10 or pH = 11) pretreatment not only significantly shortened the lag time (0.5 d) in acidification stage, but also produced more total VFAs by 23.61% and 50.12% in the MW-H2O2-OH (pH = 10) + catalase group and MW-H2O2-OH (pH = 11) + catalase group, compared with MW-H2O2-OH (pH = 10) group at 3d of hydrolysis acidification time. For MW-H2O2-OH (pH = 10) group, MW-H2O2-OH (pH = 10) + catalase group and

  4. First measurements of H2O2 and organic peroxide surface fluces by the Relaxed Eddy Accumulation technique

    NARCIS (Netherlands)

    Valverde-Canossa, J.; Ganzeveld, L.N.; Rappenglück, B.; Steinbrecher, R.; Klemm, O.; Schuster, G.; Moortgat, G.K.

    2006-01-01

    The relaxed eddy-accumulation (REA) technique was specially adapted to a high-performance liquid chromatographer (enzymatic method) and scrubbing coils to measure concentrations and fluxes of hydrogen peroxide (H2O2) and organic peroxides with a carbon chain C4, of which only methylhydroperoxide

  5. Photodegradation of amoxicillin by catalyzed Fe3+/H2O2 process

    Institute of Scientific and Technical Information of China (English)

    Xiaoming Li; Tingting Shen; Dongbo Wang; Xiu Yue; Xian Liu; Qi Yang; Jianbin Cao; Wei Zheng; Guangming Zeng

    2012-01-01

    Three oxidation processes of UV-Fe3+(EDTA)/H2O2 (UV:ultraviolet light; EDTA:ethylenediaminetetraacetic acid),UV-Fe3+/H2O2 and Fe3+/H2O2 were simultaneously investigated for the degradation of amoxicillin at pH 7.0.The results indicated that,100% amoxicillin degradation and 81.9% chemical oxygen demand (CODcr) removal could be achieved in the UV-Fe3+ (EDTA)/H2O2 process.The treatment efficiency of amoxicillin and CODcr removal were found to decrease to 59.0% and 43.0% in the UV-Fe3+/H2O2 process;39.6% and 31.3% in the Fe3+/H2O2 process.Moreover,the results of biodegradability (biological oxygen demand (BOD5)/CODCr ratio) revealed that the UV-Fe3+ (EDTA)/H2O2 process was a promising strategy to degrade amoxicillin as the biodegradability of the effluent was improved to 0.45,compared with the cases of UV-Fe3+/H2O2 (0.25) and Fe3+/H2O2 (0.10) processes.Therefore,it could be deduced that EDTA and UV light performed synergetic catalytic effect on the Fe3+/H2O2 process,enhancing the treatment efficiency.The degradation mechanisms were also investigated via UV-Vis spectra,and high performance liquid chromatography-mass spectra.The degradation pathway of amoxicillin was further proposed.

  6. Manganese catalyzed cis-dihydroxylation of electron deficient alkenes with H2O2

    NARCIS (Netherlands)

    Saisaha, Pattama; Pijper, Dirk; van Summeren, Ruben P.; Hoen, Robert; Smit, Christian; de Boer, Johannes W.; Hage, Ronald; Alsters, Paul L.; Feringa, Bernard; Browne, Wesley R.

    2010-01-01

    A practical method for the multigram scale selective cis-dihydroxylation of electron deficient alkenes such as diethyl fumarate and N-alkyl and N-aryl-maleimides using H2O2 is described. High turnovers (>1000) can be achieved with this efficient manganese based catalyst system, prepared in situ from

  7. Manganese catalyzed cis-dihydroxylation of electron deficient alkenes with H(2)O(2).

    Science.gov (United States)

    Saisaha, Pattama; Pijper, Dirk; van Summeren, Ruben P; Hoen, Rob; Smit, Christian; de Boer, Johannes W; Hage, Ronald; Alsters, Paul L; Feringa, Ben L; Browne, Wesley R

    2010-10-07

    A practical method for the multigram scale selective cis-dihydroxylation of electron deficient alkenes such as diethyl fumarate and N-alkyl and N-aryl-maleimides using H(2)O(2) is described. High turnovers (>1000) can be achieved with this efficient manganese based catalyst system, prepared in situ from a manganese salt, pyridine-2-carboxylic acid, a ketone and a base, under ambient conditions. Under optimized conditions, for diethyl fumarate at least 1000 turnovers could be achieved with only 1.5 equiv. of H(2)O(2) with d/l-diethyl tartrate (cis-diol product) as the sole product. For electron rich alkenes, such as cis-cyclooctene, this catalyst provides for efficient epoxidation.

  8. Diclofenac degradation in water by FeCeOx catalyzed H2O2: Influencing factors, mechanism and pathways.

    Science.gov (United States)

    Chong, Shan; Zhang, Guangming; Zhang, Nan; Liu, Yucan; Huang, Ting; Chang, Huazhen

    2017-07-15

    The degradation of diclofenac in a like Fenton system, FeCeO x -H 2 O 2 , was studied in details. The influencing factors, reaction kinetics, reaction mechanism and degradation pathways of diclofenac were investigated. The optimum conditions were at a solution pH of 5.0, H 2 O 2 concentration of 3.0mmol/L, diclofenac initial concentration of 0.07mmol/L, FeCeO x dosage of 0.5g/L, and 84% degradation of diclofenac was achieved within 40min. The kinetics of FeCeO x catalyzed H 2 O 2 process involved adsorption-dominating and degradation-dominating stages and fitted pseudo-second order model and pseudo-first order model, respectively. Singlet oxygen 1 O 2 was the primary intermediate oxidative species in the degradation process; superoxide radical anion O 2 - also participated in the reaction. The surface cerium and iron sites and the oxygen vacancies in the FeCeO x catalyst were proposed to play an important role in H 2 O 2 decomposition and active species generation. The detected intermediates were identified as hydroxylated derivatives (m/z of 310, 326 and 298), quinone imine compounds (m/z of 308, 278 and 264) and hydroxyl phenylamine (m/z of 178). The majority intermediates were hydroxylated derivatives and the minority was hydroxyl phenylamine. The degradation pathways were proposed to involve hydroxylation, decarboxylation, dehydrogenation and CN bond cleavage. Copyright © 2017 Elsevier B.V. All rights reserved.

  9. Hydrogen peroxide (H2O2): a review of its use in surgery.

    Science.gov (United States)

    Urban, Michael Vincent; Rath, Thomas; Radtke, Christine

    2017-11-16

    Hydrogen peroxide has been used in medicine for more than 100 years. It is known in surgery as a highly useful irrigation solution by virtue of both its hemostatic and its antimicrobial effects. Due to its possible negative effect on wound healing and its cytotoxic effect in higher concentrations, there are concerns about the safety of its use. The objective of this paper is to review the safety and beneficial effects of hydrogen peroxide.

  10. Hydrogen peroxide (H2O2) irreversibly inactivates creatine kinase from Pelodiscus sinensis by targeting the active site cysteine.

    Science.gov (United States)

    Wang, Wei; Lee, Jinhyuk; Hao, Hao; Park, Yong-Doo; Qian, Guo-Ying

    2017-12-01

    Creatine kinase (EC 2.7.3.2, CK) plays an important role in cellular energy metabolism and homeostasis by catalysing the transfer of phosphate between ATP and creatine phosphate. In this study, we investigated the effects of H 2 O 2 on PSCKM (muscle type creatine kinase from Pelodiscus sinensis) by the integrating method between enzyme kinetics and docking simulations. We found that H 2 O 2 strongly inactivated PSCKM (IC 50 =0.25mM) in a first-order kinetic process, and targeted the active site cysteine directly. A conformational study showed that H 2 O 2 did not induce the tertiary structural changes in PSCKM with no extensive exposure of hydrophobic surfaces. Sequential docking simulations between PSCKM and H 2 O 2 indicated that H 2 O 2 interacts with the ADP binding region of the active site, consistent with experimental results that demonstrated H 2 O 2 -induced inactivation. Our study demonstrates the effect of H 2 O 2 on PSCKM enzymatic function and unfolding, and provides important insight into the changes undergone by this central metabolic enzyme in ectothermic animals in response to the environment. Copyright © 2017 Elsevier B.V. All rights reserved.

  11. MECHANISTIC STUDIES OF SURFACE CATALYZED H2O2 DECOMPOSITION AND CONTAMINANT DEGRADATION IN THE PRESENCE OF SAND. (R823402)

    Science.gov (United States)

    This study examined the mechanism and kinetics of surface catalyzed hydrogen peroxide decomposition and degradation of contaminants in the presence of sand collected from an aquifer and a riverbed. Batch experiments were conducted using variable sand concentrations (0.2 to 1.0&nb...

  12. LiOH - H2O2 - H2O trinary system study for the selection of optimal conditions of lithium peroxide synthesis

    International Nuclear Information System (INIS)

    Nefedov, R A; Ferapontov, Yu A; Kozlova, N P

    2016-01-01

    Using solubility method the decay kinetics of peroxide products contained in liquid phase of LiOH - H 2 O 2 - H 2 O trinary system with 2 to 6% by wt hydrogen peroxide content in liquid phase in 21 to 33 °C temperature range has been studied. Conducted studies have allowed to determine temperature and concentration limits of solid phase existence of Li 2 O 2 ·H 2 O content, distinctness of which has been confirmed using chemical and qualitative X- ray phase analysis. Stabilizing effect of solid phase of Li 2 O 2 ·H 2 O content on hydrogen peroxide decay contained in liquid phase of LiOH - H 2 O 2 - H 2 O trinary system under conditions of experiments conducted has been shown. (paper)

  13. LiOH - H2O2 - H2O trinary system study for the selection of optimal conditions of lithium peroxide synthesis

    Science.gov (United States)

    Nefedov, R. A.; Ferapontov, Yu A.; Kozlova, N. P.

    2016-01-01

    Using solubility method the decay kinetics of peroxide products contained in liquid phase of LiOH - H2O2 - H2O trinary system with 2 to 6% by wt hydrogen peroxide content in liquid phase in 21 to 33 °C temperature range has been studied. Conducted studies have allowed to determine temperature and concentration limits of solid phase existence of Li2O2·H2O content, distinctness of which has been confirmed using chemical and qualitative X- ray phase analysis. Stabilizing effect of solid phase of Li2O2·H2O content on hydrogen peroxide decay contained in liquid phase of LiOH - H2O2 - H2O trinary system under conditions of experiments conducted has been shown.

  14. Factors affecting ultraviolet irradiation/hydrogen peroxide (UV/H2O2) degradation of mixed N-nitrosamines in water

    International Nuclear Information System (INIS)

    Zhou, Chao; Gao, Naiyun; Deng, Yang; Chu, Wenhai; Rong, Wenlei; Zhou, Shengdong

    2012-01-01

    Highlights: ► NAms with three-induced toxicity, as emerging DBPs, has caused a great public attention. ► No paper regards UV/H 2 O 2 oxidation of mixed NAms in an aquatic environment. ► The treatment effect is typically affected by a few factors in water. ► NPIP and NDPhA are the most readily and difficult to be degraded due to unique structure. ► All the NAms degradation exhibited a pseudo-first-order kinetics pattern. - Abstract: Disinfection by-products (DBPs) are a great challenge to our drinking water security. Particularly, nitrosamines (NAms), as emerging DBPs, are potently carcinogenic, mutagenic, and teratogenic, and have increasingly attained public attention. This study was to evaluate the performance of the NAms degradation by the ultraviolet (UV) irradiation (253.7 nm) in the presence of hydrogen peroxide (H 2 O 2 ). In the UV/H 2 O 2 system, hydroxyl radicals (OH·), a type of nonselective and powerful oxidant, was produced to attack the molecules of NAms. Factors affecting the treatment efficiency, including the H 2 O 2 dosage, initial NAms concentration, UV irradiation intensity, initial solution pH, and inorganic anions present in water, were evaluated. All the NAms degradation exhibited a pseudo-first-order kinetics pattern. Within 60 min, 0.1 mg/L of any NAms could be almost decomposed except NDPhA that required 120 min for complete removal, at 25 μmol/L H 2 O 2 and at initial pH 7. Results demonstrate that the UV/H 2 O 2 treatment is a viable option to control NAms in water.

  15. Detection of shock-heated hydrogen peroxide (H2O2) by off-axis cavity-enhanced absorption spectroscopy (OA-CEAS)

    KAUST Repository

    Alquaity, Awad

    2017-11-11

    Cavity-enhanced absorption spectroscopy (CEAS) is a promising technique for studying chemical reactions due to its desirable characteristics of high sensitivity and fast time-response by virtue of the increased path length and relatively short photon residence time inside the cavity. Off-axis CEAS (OA-CEAS) is particularly suited for the shock tube applications as it is insensitive to slight misalignments, and cavity noise is suppressed due to non-overlapping multiple reflections of the probe beam inside the cavity. Here, OA-CEAS is demonstrated in the mid-IR region at 1310.068 cm−1 to monitor trace concentrations of hydrogen peroxide (H2O2). This particular probe frequency was chosen to minimize interference from other species prevalent in combustion systems and in the atmosphere. The noise-equivalent detection limit is found to be 3.25 × 10−5 cm−1, and the gain factor of the cavity is 131. This corresponds to a detection limit of 74 ppm of H2O2 at typical high-temperature combustion conditions (1200 K and 1 atm) and 12 ppm of H2O2 at ambient conditions (296 K and 1 atm). To our knowledge, this is the first successful application of the OA-CEAS technique to detect H2O2 which is vital species in combustion and atmospheric science.

  16. Detection of shock-heated hydrogen peroxide (H2O2) by off-axis cavity-enhanced absorption spectroscopy (OA-CEAS)

    KAUST Repository

    Alquaity, Awad; KC, Utsav; Popov, Alber; Farooq, Aamir

    2017-01-01

    Cavity-enhanced absorption spectroscopy (CEAS) is a promising technique for studying chemical reactions due to its desirable characteristics of high sensitivity and fast time-response by virtue of the increased path length and relatively short photon residence time inside the cavity. Off-axis CEAS (OA-CEAS) is particularly suited for the shock tube applications as it is insensitive to slight misalignments, and cavity noise is suppressed due to non-overlapping multiple reflections of the probe beam inside the cavity. Here, OA-CEAS is demonstrated in the mid-IR region at 1310.068 cm−1 to monitor trace concentrations of hydrogen peroxide (H2O2). This particular probe frequency was chosen to minimize interference from other species prevalent in combustion systems and in the atmosphere. The noise-equivalent detection limit is found to be 3.25 × 10−5 cm−1, and the gain factor of the cavity is 131. This corresponds to a detection limit of 74 ppm of H2O2 at typical high-temperature combustion conditions (1200 K and 1 atm) and 12 ppm of H2O2 at ambient conditions (296 K and 1 atm). To our knowledge, this is the first successful application of the OA-CEAS technique to detect H2O2 which is vital species in combustion and atmospheric science.

  17. Selective Oxidation of Glycerol with 3% H2O2 Catalyzed by LDH-Hosted Cr(III Complex

    Directory of Open Access Journals (Sweden)

    Gongde Wu

    2015-11-01

    Full Text Available A series of layered double hydroxides (LDHs –hosted sulphonato-salen Cr(III complexes were prepared and characterized by various physico-chemical measurements, such as Fourier transform infrared spectroscopy (FTIR, ultraviolet-visible spectroscopy (UV-Vis, powder X-ray diffraction (XRD, transmission electron microscope (TEM, scanning electron microscope (SEM and elemental analysis. Additionally, their catalytic performances were investigated in the selective oxidation of glycerol (GLY using 3% H2O2 as an oxidant. It was found that all the LDH-hosted Cr(III complexes exhibited significantly enhanced catalytic performance compared to the homogeneous Cr(III complex. Additionally, it was worth mentioning that the metal composition of LDH plates played an important role in the catalytic performances of LDH-hosted Cr(III complex catalysts. Under the optimal reaction conditions, the highest GLY conversion reached 85.5% with 59.3% of the selectivity to 1,3-dihydroxyacetone (DHA. In addition, the catalytic activity remained after being recycled five times.

  18. Auxin increases the hydrogen peroxide (H2O2) concentration in tomato (Solanum lycopersicum) root tips while inhibiting root growth

    Czech Academy of Sciences Publication Activity Database

    Ivanchenko, M. G.; den Os, D.; Monshausen, G. B.; Dubrovsky, J, G.; Bednářová, Andrea; Krishnan, N.

    2013-01-01

    Roč. 112, č. 6 (2013), s. 1107-1116 ISSN 0305-7364 R&D Projects: GA ČR GAP501/10/1215 Grant - others:GA JU(CZ) 062/2011/P Institutional support: RVO:60077344 Keywords : auxin * ROS * hydrogen peroxide Subject RIV: EF - Botanics Impact factor: 3.295, year: 2013

  19. Kinetics of the H 2O 2-dependent ligninase-catalyzed oxidation of veratryl alcohol in the presence of cationic surfactant studied by spectrophotometric technique

    Science.gov (United States)

    Liu, Airong; Huang, Xirong; Song, Shaofang; Wang, Dan; Lu, Xuemei; Qu, Yinbo; Gao, Peiji

    2003-09-01

    The kinetics of ligninase-catalyzed oxidation of veratryl alcohol (VA) by H 2O 2 in the aqueous medium containing cationic surfactant cetyltrimethylammonium bromide (CTAB) has been investigated using spectrophotometric technique. Steady-state kinetic studies at different concentrations of CTAB indicate that the reaction follows a ping pong mechanism and the mechanism always holds but the kinetic parameters vary with CTAB concentrations. CTAB is a weak inhibitor for ligninase; it lowers the maximum initial velocity. CTAB also causes the Michaelis constant of H 2O 2 to decrease dramatically and that of VA to increase markedly. Based on the changes in kinetic parameters of the enzyme-catalyzed reaction at different CTAB concentrations (lower than, near to and larger than its critical micelle concentration) and the effects of the CTAB monomer and the micelles on the spectra of VA and its corresponding aldehyde, a conclusion could be made that modification of the enzymatic protein by the surfactant monomer should be responsible for the above-mentioned results.

  20. H2O2: A Dynamic Neuromodulator

    Science.gov (United States)

    Rice, Margaret E.

    2012-01-01

    Increasing evidence implicates hydrogen peroxide (H2O2) as an intra- and intercellular signaling molecule that can influence processes from embryonic development to cell death. Most research has focused on relatively slow signaling, on the order of minutes to days, via second messenger cascades. However, H2O2 can also mediate subsecond signaling via ion channel activation. This rapid signaling has been examined most thoroughly in the nigrostriatal dopamine (DA) pathway, which plays a key role in facilitating movement mediated by the basal ganglia. In DA neurons of the substantia nigra, endogenously generated H2O2 activates ATP-sensitive K+ (KATP) channels that inhibit DA neuron firing. In the striatum, H2O2 generated downstream from glutamatergic AMPA receptor activation in medium spiny neurons acts as a diffusible messenger that inhibits axonal DA release, also via KATP channels. The source of dynamically generated H2O2 is mitochondrial respiration; thus, H2O2 provides a novel link between activity and metabolism via KATP channels. Additional targets of H2O2 include transient receptor potential (TRP) channels. In contrast to the inhibitory effect of H2O2 acting via KATP channels, TRP channel activation is excitatory. This review describes emerging roles of H2O2 as a signaling agent in the nigrostriatal pathway and other basal ganglia neurons. PMID:21666063

  1. Kinetic Studies of Iron Deposition Catalyzed by Recombinant Human Liver Heavy, and Light Ferritins and Azotobacter Vinelandii Bacterioferritin Using O2 and H2O2 as Oxidants

    Science.gov (United States)

    Bunker, Jared; Lowry, Thomas; Davis, Garrett; Zhang, Bo; Brosnahan, David; Lindsay, Stuart; Costen, Robert; Choi, Sang; Arosio, Paolo; Watt, Gerald D.

    2005-01-01

    The discrepancy between predicted and measured H2O2 formation during iron deposition with recombinant heavy human liver ferritin (rHF) was attributed to reaction with the iron protein complex [Biochemistry 40 (2001) 10832-10838]. This proposal was examined by stopped-flow kinetic studies and analysis for H2O2 production using (1) rHF, and Azotobacter vinelandii bacterial ferritin (AvBF), each containing 24 identical subunits with ferroxidase centers; (2) site-altered rHF mutants with functional and dysfunctional ferroxidase centers; and (3) rccombinant human liver light ferritin (rLF), containing 110 ferroxidase center. For rHF, nearly identical pseudo-first-order rate constants of 0.18 per second at pH 7.5 were measured for Fe(2+) oxidation by both O2 and H2O2, but for rLF, the rate with O2 was 200-fold slower than that for H2O2 (k-0.22 per second). A Fe(2+)/O2 stoichiometry near 2.4 was measured for rHF and its site altered forms, suggesting formation of H2O2. Direct measurements revealed no H2O2 free in solution 0.5-10 min after all Fe(2+) was oxidized at pH 6.5 or 7.5. These results are consistent with initial H2O2 formation, which rapidly reacts in a secondary reaction with unidentified solution components. Using measured rate constants for rHF, simulations showed that steady-state H2O2 concentrations peaked at 14 pM at approx. 600 ms and decreased to zero at 10-30 s. rLF did not produce measurable H2O2 but apparently conducted the secondary reaction with H2O2. Fe(2+)/O2 values of 4.0 were measured for AvBF. Stopped-flow measurements with AvBF showed that both H2O2 and O2 react at the same rate (k=0.34 per second), that is faster than the reactions with rHF. Simulations suggest that AvBF reduces O2 directly to H2O without intermediate H2O2 formation.

  2. Activation of ERK signalling by Src family kinases (SFKs) in DRG neurons contributes to hydrogen peroxide (H2O2)-induced thermal hyperalgesia.

    Science.gov (United States)

    Singh, Ajeet Kumar; Vinayak, Manjula

    2017-10-01

    Concomitant generation of reactive oxygen species during tissue inflammation has been recognised as a major factor for the development and the maintenance of hyperalgesia, out of which H 2 O 2 is the major player. However, molecular mechanism of H 2 O 2 induced hyperalgesia is still obscure. The aim of present study is to analyse the mechanism of H 2 O 2 -induced hyperalgesia in rats. Intraplantar injection of H 2 O 2 (5, 10 and 20 µmoles/paw) induced a significant thermal hyperalgesia in the hind paw, confirmed by increased c-Fos activity in dorsal horn of spinal cord. Onset of hyperalgesia was prior to development of oxidative stress and inflammation. Rapid increase in phosphorylation of extracellular signal regulated kinase (ERK) was observed in neurons of dorsal root ganglia after 20 min of H 2 O 2 (10 µmoles/paw) administration, which gradually returned towards normal level within 24 h, following the pattern of thermal hyperalgesia. The expression of TNFR1 followed the same pattern and colocalised with pERK. ERK phosphorylation was observed in NF-200-positive and -negative neurons, indicating the involvement of ERK in C-fibres as well as in A-fibres. Intrathecal preadministration of Src family kinases (SFKs) inhibitor (PP1) and MEK inhibitor (PD98059) prevented H 2 O 2 induced augmentation of ERK phosphorylation and thermal hyperalgesia. Pretreatment of protein tyrosine phosphatases (PTPs) inhibitor (sodium orthovanadate) also diminished hyperalgesia, although it further increased ERK phosphorylation. Combination of orthovanadate with PP1 or PD98059 did not exhibit synergistic antihyperalgesic effect. The results demonstrate SFKs-mediated ERK activation and increased TNFR1 expression in nociceptive neurons during H 2 O 2 induced hyperalgesia. However, the role of PTPs in hyperalgesic behaviour needs further molecular analysis.

  3. Characterization a binderless particleboard of coffee husk using Hydrogen Peroxide (H2O2) and Ferrous Sulfate (FeSO4)

    Science.gov (United States)

    Milawarni; Nurlaili; Sariyadi

    2018-05-01

    Binderless particleboard is particleboard that can be made of a lignocellulose material which is formed into a board only by heat pressing without the addition of adhesive or resin. The particleboard in this study was made from coffee husk (endocarp) using H2O2 and FeSO4 catalyst to activate lignin coffee husk component by oxidation method. Initial treatment of coffee husk is the variation of steam then Oxidation (S + O) and Oxidation without steaming (O). In this study H2O2 and FeSO4 catalysts were varied, including H2O2 levels of 10,20,30 wt% based on particle dry weight and FeSO4 is 5 and 7.5 wt% based on H2O2 weight. From the results of the study, it can be concluded that the coffee husk particleboard whose raw material is treated oxidation without steam can improve the physical properties of binderless particleboard. Increased wt% of H2O2 and FeSO4 catalysts in the oxidation process of coffee husk particles produce binderless particleboard with good physical characteristics such as density, water content, water absorption and swelling thickness. Therefore, considering the efficient aspects of the use of chemicals, the combination of H2O2 and FeSO4 catalysts that can be made according to JIS A 5908 2003 standard are 20% H2O2 and 7.5% FeSO4. The ester linkages were detected by Fourier transform infrared spectroscopy, indicated that cross-link due to the incorporation of phenoxyl radicals.

  4. Novel Oxidative Desulfurization of a Model Fuel with H2O2 Catalyzed by AlPMo12O40 under Phase Transfer Catalyst-Free Conditions

    OpenAIRE

    José da Silva, Márcio; Faria dos Santos, Lidiane

    2013-01-01

    A novel process was developed for oxidative desulfurization (ODS) in the absence of a phase transfer catalyst (PTC) using only Keggin heteropolyacids and their aluminum salts as catalysts. Reactions were performed in biphasic mixtures of isooctane/acetonitrile, with dibenzothiophene (DBT) as a model sulfur compound and hydrogen peroxide as the oxidant. Remarkably, only the AlPMo12O40-catalyzed reactions resulted in complete oxidation of DBT into DBT sulfone, which was totally extracted by ace...

  5. Understanding the role of the catalase/peroxide genes in H2O2 resistance of E. coli serotype O157:H7 biofilms

    Science.gov (United States)

    Introduction: Escherichia coli serotype O157:H7 defenses against H2O2 include the peroxiredoxin AhpC and three catalases: KatG (catalase-peroxidase), KatE (catalase), and the plasmid-encoded KatP (catalase/peroxidase). AhpC, KatG, and KatP are induced by OxyR in exponential phase, while KatE is indu...

  6. Post-treatment of refinery wastewater effluent using a combination of AOPs (H2O2 photolysis and catalytic wet peroxide oxidation) for possible water reuse. Comparison of low and medium pressure lamp performance.

    Science.gov (United States)

    Rueda-Márquez, J J; Levchuk, I; Salcedo, I; Acevedo-Merino, A; Manzano, M A

    2016-03-15

    The main aim of this work was to study the feasibility of multi-barrier treatment (MBT) consisting of filtration, hydrogen peroxide photolysis (H2O2/UVC) and catalytic wet peroxide oxidation (CWPO) for post-treatment of petroleum refinery effluent. Also the possibility of water reuse or safe discharge was considered. The performance of MBT using medium (MP) and low (LP) pressure lamps was compared as well as operation and maintenance (O&M) cost. Decomposition of organic compounds was followed by means of gas chromatography-mass spectrometry (GC-MS), total organic carbon (TOC) and chemical oxygen demand (COD) analysis. After filtration step (25 μm) turbidity and concentration of suspended solids decreased by 92% and 80%, respectively. During H2O2/UVC process with LP lamp at optimal conditions (H2O2:TOC ratio 8 and UVC dose received by water 5.28 WUVC s cm(-2)) removal of phenolic compounds, TOC and COD was 100%, 52.3% and 84.3%, respectively. Complete elimination of phenolic compounds, 47.6% of TOC and 91% of COD was achieved during H2O2/UVC process with MP lamp at optimal conditions (H2O2:TOC ratio 5, UVC dose received by water 6.57 WUVC s cm(-2)). In order to compare performance of H2O2/UVC treatment with different experimental set up, the UVC dose required for removal of mg L(-1) of COD was suggested as a parameter and successfully applied. The hydrophilicity of H2O2/UVC effluent significantly increased which in turn enhanced the oxidation of organic compounds during CWPO step. After H2O2/UVC treatment with LP and MP lamps residual H2O2 concentration was 160 mg L(-1) and 96.5 mg L(-1), respectively. Remaining H2O2 was fully consumed during subsequent CWPO step (6 and 3.5 min of contact time for LP and MP, respectively). Total TOC and COD removal after MBT was 94.7% and 92.2% (using LP lamp) and 89.6% and 95%, (using MP lamp), respectively. The O&M cost for MBT with LP lamp was estimated to be 0.44 € m(-3) while with MP lamp it was nearly five

  7. Encapsulation of Hemin in Metal-Organic Frameworks for Catalyzing the Chemiluminescence Reaction of the H2O2-Luminol System and Detecting Glucose in the Neutral Condition.

    Science.gov (United States)

    Luo, Fenqiang; Lin, Yaolin; Zheng, Liyan; Lin, Xiaomei; Chi, Yuwu

    2015-06-03

    Novel metal-organic frameworks (MOFs) based solid catalysts have been synthesized by encapsulating Hemin into the HKUST-1 MOF materials. These have been first applied in the chemiluminescence field with outstanding performance. The functionalized MOFs not only maintain an excellent catalytic activity inheriting from Hemin but also can be cyclically utilized as solid mimic peroxidases in the neutral condition. The synthesized Hemin@HKUST-1 composites have been used to develop practical sensors for H2O2 and glucose with wide response ranges and low detection limits. It was envisioned that catalyst-functionalized MOFs for chemiluminescence sensing would have promising applications in green, selective, and sensitive detection of target analytes in the future.

  8. Algal toxicity of the alternative disinfectants performic acid (PFA), peracetic acid (PAA), chlorine dioxide (ClO2) and their by-products hydrogen peroxide (H2O2) and chlorite (ClO2-)

    DEFF Research Database (Denmark)

    Chhetri, Ravi Kumar; Baun, Anders; Andersen, Henrik Rasmus

    2017-01-01

    Environmental effect evaluation of disinfection of combined sewer overflow events with alternative chemical disinfectants requires that the environmental toxicity of the disinfectants and the main by-products of their use are known. Many disinfectants degrade quickly in water which should......: performic acid (PFA), peracetic acid (PAA) and chlorine dioxide (ClO2) as well as two by-products of their use: hydrogen peroxide (H2O2) and chlorite. All of the five chemicals investigated showed clear toxicity to the algae with well-defined dose response curves. The EC50 values ranged from 0.16 to 2.9 mg...

  9. Study of the temporal evolution of Whitening Teeth immersed in Peroxide of hydrogen (H2O2) Using Digital Image Processing

    International Nuclear Information System (INIS)

    Díaz, L; Morales, Y; Torres, C

    2015-01-01

    The esthetic dentistry reference in our society is determined by several factors, including one that produces more dissatisfaction is abnormal tooth color or that does not meet the patient's expectations. For this reason it has been designed and implemented an algorithm in MATLAB that captures, digitizes, pre-processing and analyzed dental imaging by allowing to evaluate the degree of bleaching caused by the use of peroxide of hidrogen. The samples analyzed were human teeth extracted, which were subjected to different concentrations of peroxide of hidrogen and see if they can teeth whitening when using these products, was used different concentrations and intervals of time to analysis or study of the whitening of the teeth with the hydrogen peroxide

  10. Mechanism of H2O2 dismutation catalyzed by a new catalase mimic (a non-heme dibenzotetraaza[14]annulene-Fe(III) complex): a density functional theory investigation.

    Science.gov (United States)

    Wang, Xin; Li, Shuhua; Jiang, Yuansheng

    2004-10-04

    The mechanism of H(2)O(2) dismutation catalyzed by the dibenzotetraaza[14]annulene-Fe(III) complex ([Fe(C(24)H(22)N(4)O(4))](+)) which was recently reported (Paschke, J.; Kirsch, M.; Korth, H. G.; de Groot, H.; Sustmann, R. J. Am. Chem. Soc. 2001, 123, 11099) has been investigated by density functional theory using the B3LYP hybrid functional. The quartet potential energy profile of the catalytic reaction has been explored. In the whole catalytic cycle, the rate-determining step is found to be the O-O bond homolytic cleavage, without the assistance of solvent molecules in the second coordination shell. The calculated free energy barrier for this step is 10.8 kcal/mol, which is in reasonable agreement with the experimental facts. The calculations also show that the hydroxyl and hydroperoxyl radicals may be generated in the reaction processes, but they can be efficiently quenched in strongly exothermic steps. This study provides a satisfactory explanation to the observed efficiency of the H(2)O(2) dismutation catalyzed by this complex.

  11. Algal toxicity of the alternative disinfectants performic acid (PFA), peracetic acid (PAA), chlorine dioxide (ClO2) and their by-products hydrogen peroxide (H2O2) and chlorite (ClO2-).

    Science.gov (United States)

    Chhetri, Ravi Kumar; Baun, Anders; Andersen, Henrik Rasmus

    2017-05-01

    Environmental effect evaluation of disinfection of combined sewer overflow events with alternative chemical disinfectants requires that the environmental toxicity of the disinfectants and the main by-products of their use are known. Many disinfectants degrade quickly in water which should be included in the evaluation of both their toxicity as determined in standardized tests and their possible negative effect in the water environment. Here we evaluated according to the standardized ISO 8692 test the toxicity towards the green microalgae, Pseudokirchneriella subcapitata, of three disinfectants: performic acid (PFA), peracetic acid (PAA) and chlorine dioxide (ClO 2 ) as well as two by-products of their use: hydrogen peroxide (H 2 O 2 ) and chlorite. All of the five chemicals investigated showed clear toxicity to the algae with well-defined dose response curves. The EC 50 values ranged from 0.16 to 2.9mg/L based on nominal concentrations leading to the labeling of the chemicals as either toxic or very toxic. The five investigated chemicals decreased in toxicity in the order chlorine dioxide, performic acid, peracetic acid, chlorite and hydrogen peroxide. The stability of the chemicals increased in the same order as the toxicity decrease. This indicates that even though ClO 2 has the highest environmental hazard potential, it may still be suitable as an alternative disinfectant due to its rapid degradation in water. Copyright © 2016 Elsevier GmbH. All rights reserved.

  12. Electrochemical, H2O2-Boosted Catalytic Oxidation System

    Science.gov (United States)

    Akse, James R.; Thompson, John O.; Schussel, Leonard J.

    2004-01-01

    An improved water-sterilizing aqueous-phase catalytic oxidation system (APCOS) is based partly on the electrochemical generation of hydrogen peroxide (H2O2). This H2O2-boosted system offers significant improvements over prior dissolved-oxygen water-sterilizing systems in the way in which it increases oxidation capabilities, supplies H2O2 when needed, reduces the total organic carbon (TOC) content of treated water to a low level, consumes less energy than prior systems do, reduces the risk of contamination, and costs less to operate. This system was developed as a variant of part of an improved waste-management subsystem of the life-support system of a spacecraft. Going beyond its original intended purpose, it offers the advantage of being able to produce H2O2 on demand for surface sterilization and/or decontamination: this is a major advantage inasmuch as the benign byproducts of this H2O2 system, unlike those of systems that utilize other chemical sterilants, place no additional burden of containment control on other spacecraft air- or water-reclamation systems.

  13. Combined use of O3/H2O2 and O3/Mn2+ in flotation of dairy wastewater

    Directory of Open Access Journals (Sweden)

    Marta Cristina Silva Carvalho

    2018-05-01

    Full Text Available This work investigated the degradation of organic matter present in synthetic dairy wastewater by the combination of ozonation (ozone (O3/hydrogen peroxide (H2O2 and catalytic ozonation (ozone (O3/manganese (Mn2+ associated with dispersed air flotation process. The effect of independent factors such as O3 concentration, pH and H2O2 and Mn2+ concentration was evaluated. For the flotation/O3/H2O2 treatment, the significant variables (p ≤ 0.05 were: O3 concentration (linear and quadratic effect, H2O2 concentration linear and quadratic effect, pH values (linear and quadratic effect and interaction O3 concentration versus pH. For catalytic ozonation, it was observed that the significant variable was the linear effect of O3 concentration. According to the desirability function, it was concluded that the optimal condition for the treatment of flotation/O3/H2O2 can be obtained in acidic solution using O3 concentrations greater than 42.9 mg L-1 combined with higher concentrations of H2O2 to 1071.5 mg L-1. On other hand, at pH values higher than 9.0, the addition of O3 may be neglected when using higher concentrations than 1071.5 mg L-1 of H2O2. For flotation/ozonation catalyzed by Mn2+, it was observed that metal addition did not affect treatment, resulting in an optimum condition: 53.8 mg L-1 of O3 and pH 3.6.

  14. Removal of Organic Dyes from Industrial Wastewaters Using UV/H2O2, UV/H2O2/Fe (II, UV/H2O2/Fe (III Processes

    Directory of Open Access Journals (Sweden)

    Nezamaddin Daneshvar

    2007-03-01

    Full Text Available UV/H2O2, UV/H2O2/Fe (II and UV/H2O2/Fe (III processes are very effective in removing pollutants from wastewater and can be used for treatment of dyestuff units wastewaters. In this study, Rhodamine B was used as a typical organic dye. Rhodamine B has found wide applications in wax, leather, and paper industries. The results from this study showed that this dye was degradable in the presence of hydrogen peroxide under UV-C irradiation (30W mercury light and Photo-Fenton process. The dye was resistant to UV irradiation. In the absence of UV irradiation, the decolorization efficiency was very negligible in the presence of hydrogen. The effects of different system variables such as initial dye concentration, duration of UV irradiation, and initial hydrogen peroxide concentration were investigated in the UV/H2O2 process. Investigation of the kinetics of the UV/H2O2 process showed that the semi-log plot of the dye concentration versus time was linear, suggesting a first order reaction. It was found that Rhodamine B decolorization efficiencies in the UV/H2O2/Fe (II and UV/H2O2/Fe (III processes were higher than that in the UV/H2O2 process. Furthermore, a solution containing 20 ppm of Rhodamine B was decolorized in the presence 18 mM of H2O2 under UV irradiation for 15 minutes. It was also found that addition of 0.1 mM Fe(II or Fe(III to the solution containing  20  ppm of the dye and 5 mM H2O2 under UV light  illumination decreased removal time to 10 min.

  15. Tricyclic sesquiterpene copaene prevents H2O2-induced neurotoxicity

    Directory of Open Access Journals (Sweden)

    Hasan Turkez

    2014-02-01

    Full Text Available Aim: Copaene (COP, a tricyclic sesquiterpene, is present in several essential oils of medicinal and aromatic plants and has antioxidant and anticarcinogenic features. But, very little information is known about the effects of COP on oxidative stress induced neurotoxicity. Method: We used hydrogen peroxide (H2O2 exposure for 6 h to model oxidative stress. Therefore, this experimental design allowed us to explore the neuroprotective potential of COP in H2O2-induced toxicity in rat cerebral cortex cell cultures for the first time. For this purpose, methyl thiazolyl tetrazolium (MTT and lactate dehydrogenase (LDH release assays were carried out to evaluate cytotoxicity. Total antioxidant capacity (TAC and total oxidative stress (TOS parameters were used to evaluate oxidative changes. In addition to determining of 8-hydroxy-2-deoxyguanosine (8-OH-dG levels, the single cell gel electrophoresis (SCGE or comet assay was also performed for measuring the resistance of neuronal DNA to H2O2-induced challenge. Result: The results of this study showed that survival and TAC levels of the cells decreased, while TOS, 8-OH-dG levels and the mean values of the total scores of cells showing DNA damage increased in the H2O2 alone treated cultures. But pre-treatment of COP suppressed the cytotoxicity, genotoxicity and oxidative stress which were increased by H2O2. Conclusion: It is proposed that COP as a natural product with an antioxidant capacity in mitigating oxidative injuries in the field of neurodegenerative diseases. [J Intercult Ethnopharmacol 2014; 3(1.000: 21-28

  16. The Role of Peroxiredoxins in the Transduction of H2O2 Signals.

    Science.gov (United States)

    Rhee, Sue Goo; Woo, Hyun Ae; Kang, Dongmin

    2018-03-01

    Hydrogen peroxide (H 2 O 2 ) is produced on stimulation of many cell surface receptors and serves as an intracellular messenger in the regulation of diverse physiological events, mostly by oxidizing cysteine residues of effector proteins. Mammalian cells express multiple H 2 O 2 -eliminating enzymes, including catalase, glutathione peroxidase (GPx), and peroxiredoxin (Prx). A conserved cysteine in Prx family members is the site of oxidation by H 2 O 2 . Peroxiredoxins possess a high-affinity binding site for H 2 O 2 that is lacking in catalase and GPx and which renders the catalytic cysteine highly susceptible to oxidation, with a rate constant several orders of magnitude greater than that for oxidation of cysteine in most H 2 O 2 effector proteins. Moreover, Prxs are abundant and present in all subcellular compartments. The cysteines of most H 2 O 2 effectors are therefore at a competitive disadvantage for reaction with H 2 O 2 . Recent Advances: Here we review intracellular sources of H 2 O 2 as well as H 2 O 2 target proteins classified according to biochemical and cellular function. We then highlight two strategies implemented by cells to overcome the kinetic disadvantage of most target proteins with regard to H 2 O 2 -mediated oxidation: transient inactivation of local Prx molecules via phosphorylation, and indirect oxidation of target cysteines via oxidized Prx. Critical Issues and Future Directions: Recent studies suggest that only a small fraction of the total pools of Prxs and H 2 O 2 effector proteins localized in specific subcellular compartments participates in H 2 O 2 signaling. Development of sensitive tools to selectively detect phosphorylated Prxs and oxidized effector proteins is needed to provide further insight into H 2 O 2 signaling. Antioxid. Redox Signal. 28, 537-557.

  17. Human milk H2O2 content: does it benefit preterm infants?

    Science.gov (United States)

    Cieslak, Monika; Ferreira, Cristina H F; Shifrin, Yulia; Pan, Jingyi; Belik, Jaques

    2018-03-01

    BackgroundHuman milk has a high content of the antimicrobial compound hydrogen peroxide (H 2 O 2 ). As opposed to healthy full-term infants, preterm neonates are fed previously expressed and stored maternal milk. These practices may favor H 2 O 2 decomposition, thus limiting its potential benefit to preterm infants. The goal of this study was to evaluate the factors responsible for H 2 O 2 generation and degradation in breastmilk.MethodsHuman donors' and rats' milk, along with rat mammary tissue were evaluated. The role of oxytocin and xanthine oxidase on H 2 O 2 generation, its pH-dependent stability, as well as its degradation via lactoperoxidase and catalase was measured in milk.ResultsBreast tissue xanthine oxidase is responsible for the H 2 O 2 generation and its milk content is dependent on oxytocin stimulation. Stability of the human milk H 2 O 2 content is pH-dependent and greatest in the acidic range. Complete H 2 O 2 degradation occurs when human milk is maintained, longer than 10 min, at room temperature and this process is suppressed by lactoperoxidase and catalase inhibition.ConclusionFresh breastmilk H 2 O 2 content is labile and quickly degrades at room temperature. Further investigation on breastmilk handling techniques to preserve its H 2 O 2 content, when gavage-fed to preterm infants is warranted.

  18. Comparison of genes required for H2O2 resistance in Streptococcus gordonii and Streptococcus sanguinis

    Science.gov (United States)

    Xu, Yifan; Itzek, Andreas

    2014-01-01

    Hydrogen peroxide (H2O2) is produced by several members of the genus Streptococcus mainly through the pyruvate oxidase SpxB under aerobic growth conditions. The acute toxic nature of H2O2 raises the interesting question of how streptococci cope with intrinsically produced H2O2, which subsequently accumulates in the microenvironment and threatens the closely surrounding population. Here, we investigate the H2O2 susceptibility of oral Streptococcus gordonii and Streptococcus sanguinis and elucidate potential mechanisms of how they protect themselves from the deleterious effect of H2O2. Both organisms are considered primary colonizers and occupy the same intraoral niche making them potential targets for H2O2 produced by other species. We demonstrate that S. gordonii produces relatively more H2O2 and has a greater ability for resistance to H2O2 stress. Functional studies show that, unlike in Streptococcus pneumoniae, H2O2 resistance is not dependent on a functional SpxB and confirms the important role of the ferritin-like DNA-binding protein Dps. However, the observed increased H2O2 resistance of S. gordonii over S. sanguinis is likely to be caused by an oxidative stress protection machinery present even under anaerobic conditions, while S. sanguinis requires a longer period of time for adaptation. The ability to produce more H2O2 and be more resistant to H2O2 might aid S. gordonii in the competitive oral biofilm environment, since it is lower in abundance yet manages to survive quite efficiently in the oral biofilm. PMID:25280752

  19. Characterization and optimization of cathodic conditions for H2O2 synthesis in microbial electrochemical cells

    Data.gov (United States)

    U.S. Environmental Protection Agency — H2O2_COD_EPA: Measurements of hydrogen peroxide and COD concentrations for water samples from the MEC reactors. MEC_acclimation: raw data for current and voltage of...

  20. Reactivity and operational stability of N-tailed TAMLs through kinetic studies of the catalyzed oxidation of orange II by H2 O2 : synthesis and X-ray structure of an N-phenyl TAML.

    Science.gov (United States)

    Warner, Genoa R; Mills, Matthew R; Enslin, Clarissa; Pattanayak, Shantanu; Panda, Chakadola; Panda, Tamas Kumar; Gupta, Sayam Sen; Ryabov, Alexander D; Collins, Terrence J

    2015-04-13

    The catalytic activity of the N-tailed ("biuret") TAML (tetraamido macrocyclic ligand) activators [Fe{4-XC6 H3 -1,2-(NCOCMe2 NCO)2 NR}Cl](2-) (3; N atoms in boldface are coordinated to the central iron atom; the same nomenclature is used in for compounds 1 and 2 below), [X, R=H, Me (a); NO2 , Me (b); H, Ph (c)] in the oxidative bleaching of Orange II dye by H2 O2 in aqueous solution is mechanistically compared with the previously investigated activator [Fe{4-XC6 H3 -1,2-(NCOCMe2 NCO)2 CMe2 }OH2 ](-) (1) and the more aggressive analogue [Fe(Me2 C{CON(1,2-C6 H3 -4-X)NCO}2 )OH2 ](-) (2). Catalysis by 3 of the reaction between H2 O2 and Orange II (S) occurs according to the rate law found generally for TAML activators (v=kI kII [Fe(III) ][S][H2 O2 ]/(kI [H2 O2 ]+kII [S]) and the rate constants kI and kII at pH 7 both decrease within the series 3 b>3 a>3 c. The pH dependency of kI and kII was investigated for 3 a. As with all TAML activators studied to-date, bell-shaped profiles were found for both rate constants. For kI , the maximal activity was found at pH 10.7 marking it as having similar reactivity to 1 a. For kII , the broad bell pH profile exhibits a maximum at pH about 10.5. The condition kI ≪kII holds across the entire pH range studied. Activator 3 b exhibits pronounced activity in neutral to slightly basic aqueous solutions making it worthy of consideration on a technical performance basis for water treatment. The rate constants ki for suicidal inactivation of the active forms of complexes 3 a-c were calculated using the general formula ln([S0 ]/[S∞ ])=(kII /ki )[Fe(III) ]; here [Fe(III) ], [S0 ], and [S∞ ] are the total catalyst concentration and substrate concentration at time zero and infinity, respectively. The synthesis and X-ray characterization of 3 c are also described. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  1. A Mild Catalytic Oxidation System: FePcOTf/H2O2 Applied for Cyclohexene Dihydroxylation

    Directory of Open Access Journals (Sweden)

    Baocheng Zhou

    2015-05-01

    Full Text Available Iron (III phthalocyanine complexes were employed for the first time as a mild and efficient Lewis acid catalyst in the selective oxidation of cyclohexene to cyclohexane-1,2-diol. It was found that the catalyst FePcOTf shown excellent conversion and moderate selectivity relative to other iron (III phthalocyanine complexes. The optimum conditions of the oxidation reaction catalyzed by FePcOTf/H2O2 have been researched in this paper. Iron (III phthalocyanine triflate (1 mol % as catalyst, hydrogen peroxide as oxidant, methanol as solvent, and a mole ratio of substrate and oxidant (H2O2 of 1:1 were used for achieving moderate yields of 1,2-diols under reflux conditions after eight hours.

  2. Study on tribological and electrochemistry properties of metal materials in H2O2 solutions

    Science.gov (United States)

    Yuan, Chengqing; Yu, Li; Li, Jian; Yan, Xinping

    2012-03-01

    Hydrogen peroxide (H2O2) is a kind of ideal green propellant. It is crucial to study the wear behavior and failure modes of the metal materials under the strong oxidizing environment of H2O2. This study aims to investigate the wear of rubbing pairs of 2Cr13 stainless steel against 1045 metal in H2O2 solutions, which has a great effect on wear, the decomposition and damage mechanism of materials. The comparison analysis of the friction coefficients, wear mass loss, worn surface topographies and current densities was conducted under different concentrations of H2O2 solutions. There were significant differences in the tribological and electrochemistry properties of the rubbing pairs in different H2O2 solutions.

  3. H2O2 INDUCES DELAYED HYPEREXCITABILITY IN NUCLEUS TRACTUS SOLITARII NEURONS

    Science.gov (United States)

    Ostrowski, Tim D.; Hasser, Eileen M.; Heesch, Cheryl M.; Kline, David D.

    2014-01-01

    Hydrogen peroxide (H2O2) is a stable reactive oxygen species and potent neuromodulator of cellular and synaptic activity. Centrally, endogenous H2O2 is elevated during bouts of hypoxia-reoxygenation, a variety of disease states, and aging. The nucleus tractus solitarii (nTS) is the central termination site of visceral afferents for homeostatic reflexes and contributes to reflex alterations during these conditions. We determined the extent to which H2O2 modulates synaptic and membrane properties in nTS neurons in rat brainstem slices. Stimulation of the tractus solitarii (which contains the sensory afferent fibers) evoked synaptic currents that were not altered by 10 – 500 μM H2O2. However, 500 μM H2O2 modulated several intrinsic membrane properties of nTS neurons, including a decrease in input resistance, hyperpolarization of resting membrane potential (RMP) and action potential (AP) threshold (THR), and an initial reduction in AP discharge to depolarizing current. H2O2 increased conductance of barium-sensitive potassium currents, and block of these currents ablated H2O2-induced changes in RMP, input resistance and AP discharge. Following washout of H2O2 AP discharge was enhanced due to depolarization of RMP and a partially maintained hyperpolarization of THR. Hyperexcitability persisted with repeated H2O2 exposure. H2O2 effects on RMP and THR were ablated by intracellular administration of the antioxidant catalase, which was immunohistochemically identified in neurons throughout the nTS. Thus, H2O2 initially reduces excitability of nTS neurons that is followed by sustained hyperexcitability, which may play a profound role in cardiorespiratory reflexes. PMID:24397952

  4. Dexmedetomidine attenuates H2O2-induced cell death in human osteoblasts.

    Science.gov (United States)

    Yoon, Ji-Young; Park, Jeong-Hoon; Kim, Eun-Jung; Park, Bong-Soo; Yoon, Ji-Uk; Shin, Sang-Wook; Kim, Do-Wan

    2016-12-01

    Reactive oxygen species play critical roles in homeostasis and cell signaling. Dexmedetomidine, a specific agonist of the α 2 -adrenoceptor, has been commonly used for sedation, and it has been reported to have a protective effect against oxidative stress. In this study, we investigated whether dexmedetomidine has a protective effect against H 2 O 2 -induced oxidative stress and the mechanism of H 2 O 2 -induced cell death in normal human fetal osteoblast (hFOB) cells. Cells were divided into three groups: control group-cells were incubated in normoxia without dexmedetomidine, hydrogen peroxide (H 2 O 2 ) group-cells were exposed to H 2 O 2 (200 µM) for 2 h, and Dex/H 2 O 2 group-cells were pretreated with dexmedetomidine (5 µM) for 2 h then exposed to H 2 O 2 (200 µM) for 2 h. Cell viability and apoptosis were evaluated. Osteoblast maturation was determined by assaying bone nodular mineralization. Expression levels of bone-related proteins were determined by western blot. Cell viability was significantly decreased in the H 2 O 2 group compared with the control group, and this effect was improved by dexmedetomidine. The Hoechst 33342 and Annexin-V FITC/PI staining revealed that dexmedetomidine effectively decreased H 2 O 2 -induced hFOB cell apoptosis. Dexmedetomidine enhanced the mineralization of hFOB cells when compared to the H 2 O 2 group. In western blot analysis, bone-related protein was increased in the Dex/H 2 O 2 group. We demonstrated the potential therapeutic value of dexmedetomidine in H 2 O 2 -induced oxidative stress by inhibiting apoptosis and enhancing osteoblast activity. Additionally, the current investigation could be evidence to support the antioxidant potential of dexmedetomidine in vitro.

  5. Image-Based Measurement of H2O2 Reaction-Diffusion in Wounded Zebrafish Larvae.

    Science.gov (United States)

    Jelcic, Mark; Enyedi, Balázs; Xavier, João B; Niethammer, Philipp

    2017-05-09

    Epithelial injury induces rapid recruitment of antimicrobial leukocytes to the wound site. In zebrafish larvae, activation of the epithelial NADPH oxidase Duox at the wound margin is required early during this response. Before injury, leukocytes are near the vascular region, that is, ∼100-300 μm away from the injury site. How Duox establishes long-range signaling to leukocytes is unclear. We conceived that extracellular hydrogen peroxide (H 2 O 2 ) generated by Duox diffuses through the tissue to directly regulate chemotactic signaling in these cells. But before it can oxidize cellular proteins, H 2 O 2 must get past the antioxidant barriers that protect the cellular proteome. To test whether, or on which length scales this occurs during physiological wound signaling, we developed a computational method based on reaction-diffusion principles that infers H 2 O 2 degradation rates from intravital H 2 O 2 -biosensor imaging data. Our results indicate that at high tissue H 2 O 2 levels the peroxiredoxin-thioredoxin antioxidant chain becomes overwhelmed, and H 2 O 2 degradation stalls or ceases. Although the wound H 2 O 2 gradient reaches deep into the tissue, it likely overcomes antioxidant barriers only within ∼30 μm of the wound margin. Thus, Duox-mediated long-range signaling may require other spatial relay mechanisms besides extracellular H 2 O 2 diffusion. Copyright © 2017 Biophysical Society. Published by Elsevier Inc. All rights reserved.

  6. Three-dimensional WS2 nanosheet networks for H2O2 produced for cell signaling

    Science.gov (United States)

    Tang, Jing; Quan, Yingzhou; Zhang, Yueyu; Jiang, Min; Al-Enizi, Abdullah M.; Kong, Biao; An, Tiance; Wang, Wenshuo; Xia, Limin; Gong, Xingao; Zheng, Gengfeng

    2016-03-01

    Hydrogen peroxide (H2O2) is an important molecular messenger for cellular signal transduction. The capability of direct probing of H2O2 in complex biological systems can offer potential for elucidating its manifold roles in living systems. Here we report the fabrication of three-dimensional (3D) WS2 nanosheet networks with flower-like morphologies on a variety of conducting substrates. The semiconducting WS2 nanosheets with largely exposed edge sites on flexible carbon fibers enable abundant catalytically active sites, excellent charge transfer, and high permeability to chemicals and biomaterials. Thus, the 3D WS2-based nano-bio-interface exhibits a wide detection range, high sensitivity and rapid response time for H2O2, and is capable of visualizing endogenous H2O2 produced in living RAW 264.7 macrophage cells and neurons. First-principles calculations further demonstrate that the enhanced sensitivity of probing H2O2 is attributed to the efficient and spontaneous H2O2 adsorption on WS2 nanosheet edge sites. The combined features of 3D WS2 nanosheet networks suggest attractive new opportunities for exploring the physiological roles of reactive oxygen species like H2O2 in living systems.Hydrogen peroxide (H2O2) is an important molecular messenger for cellular signal transduction. The capability of direct probing of H2O2 in complex biological systems can offer potential for elucidating its manifold roles in living systems. Here we report the fabrication of three-dimensional (3D) WS2 nanosheet networks with flower-like morphologies on a variety of conducting substrates. The semiconducting WS2 nanosheets with largely exposed edge sites on flexible carbon fibers enable abundant catalytically active sites, excellent charge transfer, and high permeability to chemicals and biomaterials. Thus, the 3D WS2-based nano-bio-interface exhibits a wide detection range, high sensitivity and rapid response time for H2O2, and is capable of visualizing endogenous H2O2 produced in

  7. H2O2 space shuttle APU

    Science.gov (United States)

    1975-01-01

    A cryogenic H2-O2 auxiliary power unit (APU) was developed and successfully demonstrated. It has potential application as a minimum weight alternate to the space shuttle baseline APU because of its (1) low specific propellant consumption and (2) heat sink capabilities that reduce the amount of expendable evaporants. A reference system was designed with the necessary heat exchangers, combustor, turbine-gearbox, valves, and electronic controls to provide 400 shp to two aircraft hydraulic pumps. Development testing was carried out first on the combustor and control valves. This was followed by development of the control subsystem including the controller, the hydrogen and oxygen control valves, the combustor, and a turbine simulator. The complete APU system was hot tested for 10 hr with ambient and cryogenic propellants. Demonstrated at 95 percent of design power was 2.25 lb/hp-hr. At 10 percent design power, specific propellant consumption was 4 lb/hp-hr with space simulated exhaust and 5.2 lb/hp-hr with ambient exhaust. A 10 percent specific propellant consumption improvement is possible with some seal modifications. It was demonstrated that APU power levels could be changed by several hundred horsepower in less than 100 msec without exceeding allowable turbine inlet temperatures or turbine speed.

  8. Characterization of a real time H2O2 monitor for use in studies on H2O2 production by antibodies and cells.

    Science.gov (United States)

    Sharma, Harish A; Balcavage, Walter X; Waite, Lee R; Johnson, Mary T; Nindl, Gabi

    2003-01-01

    It was recently shown that antibodies catalyze a reaction between water and ultraviolet light (UV) creating singlet oxygen and ultimately H2O2. Although the in vivo relevance of these antibody reactions is unclear, it is interesting that among a wide variety of non-antibody proteins tested, the T cell receptor is the only protein with similar capabilities. In clinical settings UV is believed to exert therapeutic effects by eliminating inflammatory epidermal T cells and we hypothesized that UV-triggered H2O2 production is involved in this process. To test the hypothesis we developed tools to study production of H2O2 by T cell receptors with the long-term goal of understanding, and improving, UV phototherapy. Here, we report the development of an inexpensive, real time H2O2 monitoring system having broad applicability. The detector is a Clark oxygen electrode (Pt, Ag/AgCl) modified to detect UV-driven H2O2 production. Modifications include painting the electrode black to minimize UV effects on the Ag/AgCl electrode and the use of hydrophilic, large pore Gelnots electrode membranes. Electrode current was converted to voltage and then amplified and recorded using a digital multimeter coupled to a PC. A reaction vessel with a quartz window was developed to maintain constant temperature while permitting UV irradiation of the samples. The sensitivity and specificity of the system and its use in cell-free and cell-based assays will be presented. In a cellfree system, production of H2O2 by CD3 antibodies was confirmed using our real time H2O2 monitoring method. Additionally we report the finding that splenocytes and Jurkat T cells also produce H2O2 when exposed to UV light.

  9. The influence of solar ultraviolet radiation on the photochemical production of H2O2 in the equatorial Atlantic Ocean

    NARCIS (Netherlands)

    Gerringa, LJA; Rijkenberg, MJA; Timmermans, KR; Buma, AGJ

    Hydrogen peroxide (H2O2) was measured in marine surface waters of the eastern Atlantic Ocean between 25degreesN and 25degreesS. H2O2 concentrations decreased from 80 nM in the north to 20 nM in the south, in agreement with earlier observations. A diel cycle of H2O2 production as a function of

  10. Enhanced catalytic four-electron dioxygen (O2) and two-electron hydrogen peroxide (H2O2) reduction with a copper(II) complex possessing a pendant ligand pivalamido group.

    Science.gov (United States)

    Kakuda, Saya; Peterson, Ryan L; Ohkubo, Kei; Karlin, Kenneth D; Fukuzumi, Shunichi

    2013-05-01

    A copper complex, [(PV-tmpa)Cu(II)](ClO4)2 (1) [PV-tmpa = bis(pyrid-2-ylmethyl){[6-(pivalamido)pyrid-2-yl]methyl}amine], acts as a more efficient catalyst for the four-electron reduction of O2 by decamethylferrocene (Fc*) in the presence of trifluoroacetic acid (CF3COOH) in acetone as compared with the corresponding copper complex without a pivalamido group, [(tmpa)Cu(II)](ClO4)2 (2) (tmpa = tris(2-pyridylmethyl)amine). The rate constant (k(obs)) of formation of decamethylferrocenium ion (Fc*(+)) in the catalytic four-electron reduction of O2 by Fc* in the presence of a large excess CF3COOH and O2 obeyed first-order kinetics. The k(obs) value was proportional to the concentration of catalyst 1 or 2, whereas the k(obs) value remained constant irrespective of the concentration of CF3COOH or O2. This indicates that electron transfer from Fc* to 1 or 2 is the rate-determining step in the catalytic cycle of the four-electron reduction of O2 by Fc* in the presence of CF3COOH. The second-order catalytic rate constant (k(cat)) for 1 is 4 times larger than the corresponding value determined for 2. With the pivalamido group in 1 compared to 2, the Cu(II)/Cu(I) potentials are -0.23 and -0.05 V vs SCE, respectively. However, during catalytic turnover, the CF3COO(-) anion present readily binds to 2 shifting the resulting complex's redox potential to -0.35 V. The pivalamido group in 1 is found to inhibit anion binding. The overall effect is to make 1 easier to reduce (relative to 2) during catalysis, accounting for the relative k(cat) values observed. 1 is also an excellent catalyst for the two-electron two-proton reduction of H2O2 to water and is also more efficient than is 2. For both complexes, reaction rates are greater than for the overall four-electron O2-reduction to water, an important asset in the design of catalysts for the latter.

  11. Transcriptome analysis of H2O2-treated wheat seedlings reveals a H2O2-responsive fatty acid desaturase gene participating in powdery mildew resistance.

    Directory of Open Access Journals (Sweden)

    Aili Li

    Full Text Available Hydrogen peroxide (H(2O(2 plays important roles in plant biotic and abiotic stress responses. However, the effect of H(2O(2 stress on the bread wheat transcriptome is still lacking. To investigate the cellular and metabolic responses triggered by H(2O(2, we performed an mRNA tag analysis of wheat seedlings under 10 mM H(2O(2 treatment for 6 hour in one powdery mildew (PM resistant (PmA and two susceptible (Cha and Han lines. In total, 6,156, 6,875 and 3,276 transcripts were found to be differentially expressed in PmA, Han and Cha respectively. Among them, 260 genes exhibited consistent expression patterns in all three wheat lines and may represent a subset of basal H(2O(2 responsive genes that were associated with cell defense, signal transduction, photosynthesis, carbohydrate metabolism, lipid metabolism, redox homeostasis, and transport. Among genes specific to PmA, 'transport' activity was significantly enriched in Gene Ontology analysis. MapMan classification showed that, while both up- and down- regulations were observed for auxin, abscisic acid, and brassinolides signaling genes, the jasmonic acid and ethylene signaling pathway genes were all up-regulated, suggesting H(2O(2-enhanced JA/Et functions in PmA. To further study whether any of these genes were involved in wheat PM response, 19 H(2O(2-responsive putative defense related genes were assayed in wheat seedlings infected with Blumeria graminis f. sp. tritici (Bgt. Eight of these genes were found to be co-regulated by H(2O(2 and Bgt, among which a fatty acid desaturase gene TaFAD was then confirmed by virus induced gene silencing (VIGS to be required for the PM resistance. Together, our data presents the first global picture of the wheat transcriptome under H(2O(2 stress and uncovers potential links between H(2O(2 and Bgt responses, hence providing important candidate genes for the PM resistance in wheat.

  12. H2O2 modulates the energetic metabolism of the cloud microbiome

    Directory of Open Access Journals (Sweden)

    N. Wirgot

    2017-12-01

    Full Text Available Chemical reactions in clouds lead to oxidation processes driven by radicals (mainly HO⚫, NO3⚫, or HO2⚫ or strong oxidants such as H2O2, O3, nitrate, and nitrite. Among those species, hydrogen peroxide plays a central role in the cloud chemistry by driving its oxidant capacity. In cloud droplets, H2O2 is transformed by microorganisms which are metabolically active. Biological activity can therefore impact the cloud oxidant capacity. The present article aims at highlighting the interactions between H2O2 and microorganisms within the cloud system. First, experiments were performed with selected strains studied as a reference isolated from clouds in microcosms designed to mimic the cloud chemical composition, including the presence of light and iron. Biotic and abiotic degradation rates of H2O2 were measured and results showed that biodegradation was the most efficient process together with the photo-Fenton process. H2O2 strongly impacted the microbial energetic state as shown by adenosine triphosphate (ATP measurements in the presence and absence of H2O2. This ATP depletion was not due to the loss of cell viability. Secondly, correlation studies were performed based on real cloud measurements from 37 cloud samples collected at the PUY station (1465 m a.s.l., France. The results support a strong correlation between ATP and H2O2 concentrations and confirm that H2O2 modulates the energetic metabolism of the cloud microbiome. The modulation of microbial metabolism by H2O2 concentration could thus impact cloud chemistry, in particular the biotransformation rates of carbon compounds, and consequently can perturb the way the cloud system is modifying the global atmospheric chemistry.

  13. H2O2 modulates the energetic metabolism of the cloud microbiome

    Science.gov (United States)

    Wirgot, Nolwenn; Vinatier, Virginie; Deguillaume, Laurent; Sancelme, Martine; Delort, Anne-Marie

    2017-12-01

    Chemical reactions in clouds lead to oxidation processes driven by radicals (mainly HO⚫, NO3⚫, or HO2⚫) or strong oxidants such as H2O2, O3, nitrate, and nitrite. Among those species, hydrogen peroxide plays a central role in the cloud chemistry by driving its oxidant capacity. In cloud droplets, H2O2 is transformed by microorganisms which are metabolically active. Biological activity can therefore impact the cloud oxidant capacity. The present article aims at highlighting the interactions between H2O2 and microorganisms within the cloud system. First, experiments were performed with selected strains studied as a reference isolated from clouds in microcosms designed to mimic the cloud chemical composition, including the presence of light and iron. Biotic and abiotic degradation rates of H2O2 were measured and results showed that biodegradation was the most efficient process together with the photo-Fenton process. H2O2 strongly impacted the microbial energetic state as shown by adenosine triphosphate (ATP) measurements in the presence and absence of H2O2. This ATP depletion was not due to the loss of cell viability. Secondly, correlation studies were performed based on real cloud measurements from 37 cloud samples collected at the PUY station (1465 m a.s.l., France). The results support a strong correlation between ATP and H2O2 concentrations and confirm that H2O2 modulates the energetic metabolism of the cloud microbiome. The modulation of microbial metabolism by H2O2 concentration could thus impact cloud chemistry, in particular the biotransformation rates of carbon compounds, and consequently can perturb the way the cloud system is modifying the global atmospheric chemistry.

  14. Photogeneration of H2O2 in SPEEK/PVA aqueous polymer solutions.

    Science.gov (United States)

    Little, Brian K; Lockhart, PaviElle; Slaten, B L; Mills, G

    2013-05-23

    Photolysis of air-saturated aqueous solutions containing sulphonated poly(ether etherketone) and poly(vinyl alcohol) results in the generation of hydrogen peroxide. Consumption of oxygen and H2O2 formation are initially concurrent processes with a quantum yield of peroxide generation of 0.02 in stirred or unstirred solutions within the range of 7 ≤ pH ≤ 9. The results are rationalized in terms of O2 reduction by photogenerated α-hydroxy radicals of the polymeric ketone in competition with radical-radical processes that consume the macromolecular reducing agents. Generation of H2O2 is controlled by the photochemical transformation that produces the polymer radicals, which is most efficient in neutral and slightly alkaline solutions. Quenching of the excited state of the polyketone by both H3O(+) and OH(-) affect the yields of the reducing macromolecular radicals and of H2O2. Deprotonation of the α-hydroxy polymeric radicals at pH > 9 accelerate their decay and contribute to suppressing the peroxide yields in basic solutions. Maxima in [H2O2] are observed when illuminations are performed with static systems, where O2 reduction is faster than diffusion of oxygen into the solutions. Under such conditions H2O2 can compete with O2 for the reducing radicals resulting in a consumption of the peroxide.

  15. H2O2 Production in Microbial Electrochemical Cells Fed with Primary Sludge.

    Science.gov (United States)

    Ki, Dongwon; Popat, Sudeep C; Rittmann, Bruce E; Torres, César I

    2017-06-06

    We developed an energy-efficient, flat-plate, dual-chambered microbial peroxide producing cell (MPPC) as an anaerobic energy-conversion technology for converting primary sludge (PS) at the anode and producing hydrogen peroxide (H 2 O 2 ) at the cathode. We operated the MPPC with a 9 day hydraulic retention time in the anode. A maximum H 2 O 2 concentration of ∼230 mg/L was achieved in 6 h of batch cathode operation. This is the first demonstration of H 2 O 2 production using PS in an MPPC, and the energy requirement for H 2 O 2 production was low (∼0.87 kWh/kg H 2 O 2 ) compared to previous studies using real wastewaters. The H 2 O 2 gradually decayed with time due to the diffusion of H 2 O 2 -scavenging carbonate ions from the anode. We compared the anodic performance with a H 2 -producing microbial electrolysis cell (MEC). Both cells (MEC and MPPC) achieved ∼30% Coulombic recovery. While similar microbial communities were present in the anode suspension and anode biofilm for the two operating modes, aerobic bacteria were significant only on the side of the anode facing the membrane in the MPPC. Coupled with a lack of methane production in the MPPC, the presence of aerobic bacteria suggests that H 2 O 2 diffusion to the anode side caused inhibition of methanogens, which led to the decrease in chemical oxygen demand removal. Thus, the Coulombic efficiency was ∼16% higher in the MPPC than in the MEC (64% versus 48%, respectively).

  16. Influence of H2O2 on LPG fuel performance evaluation

    International Nuclear Information System (INIS)

    Khan, Muhammad Saad; Ahmed, Iqbal; Mutalib, Mohammad Ibrahim bin Abdul; Nadeem, Saad; Ali, Shahid

    2014-01-01

    The objective of this mode of combustion is to insertion of hydrogen peroxide (H 2 O 2 ) to the Liquefied Petroleum Gas (LPG) combustion on spark plug ignition engines. The addition of hydrogen peroxide may probably decrease the formation of NO x , CO x and unburned hydrocarbons. Hypothetically, Studies have shown that addition of hydrogen peroxide to examine the performance of LPG/H 2 O 2 mixture in numerous volumetric compositions starting from lean LPG until obtaining a better composition can reduce the LPG fuel consumption. The theory behind this idea is that, the addition of H 2 O 2 can cover the lean operation limit, increase the lean burn ability, diminution the burn duration along with controlling the exhaust emission by significantly reducing the greenhouse gaseous

  17. Catalase-dependent H2O2 consumption by cardiac mitochondria and redox-mediated loss in insulin signaling.

    Science.gov (United States)

    Rindler, Paul M; Cacciola, Angela; Kinter, Michael; Szweda, Luke I

    2016-11-01

    We have recently demonstrated that catalase content in mouse cardiac mitochondria is selectively elevated in response to high dietary fat, a nutritional state associated with oxidative stress and loss in insulin signaling. Catalase and various isoforms of glutathione peroxidase and peroxiredoxin each catalyze the consumption of H 2 O 2 Catalase, located primarily within peroxisomes and to a lesser extent mitochondria, has a low binding affinity for H 2 O 2 relative to glutathione peroxidase and peroxiredoxin. As such, the contribution of catalase to mitochondrial H 2 O 2 consumption is not well understood. In the current study, using highly purified cardiac mitochondria challenged with micromolar concentrations of H 2 O 2 , we found that catalase contributes significantly to mitochondrial H 2 O 2 consumption. In addition, catalase is solely responsible for removal of H 2 O 2 in nonrespiring or structurally disrupted mitochondria. Finally, in mice fed a high-fat diet, mitochondrial-derived H 2 O 2 is responsible for diminished insulin signaling in the heart as evidenced by reduced insulin-stimulated Akt phosphorylation. While elevated mitochondrial catalase content (∼50%) enhanced the capacity of mitochondria to consume H 2 O 2 in response to high dietary fat, the selective increase in catalase did not prevent H 2 O 2 -induced loss in cardiac insulin signaling. Taken together, our results indicate that mitochondrial catalase likely functions to preclude the formation of high levels of H 2 O 2 without perturbing redox-dependent signaling. Copyright © 2016 the American Physiological Society.

  18. Photosynthesis-dependent H2O2 transfer from chloroplasts to nuclei provides a high-light signalling mechanism.

    Science.gov (United States)

    Exposito-Rodriguez, Marino; Laissue, Pierre Philippe; Yvon-Durocher, Gabriel; Smirnoff, Nicholas; Mullineaux, Philip M

    2017-06-29

    Chloroplasts communicate information by signalling to nuclei during acclimation to fluctuating light. Several potential operating signals originating from chloroplasts have been proposed, but none have been shown to move to nuclei to modulate gene expression. One proposed signal is hydrogen peroxide (H 2 O 2 ) produced by chloroplasts in a light-dependent manner. Using HyPer2, a genetically encoded fluorescent H 2 O 2 sensor, we show that in photosynthetic Nicotiana benthamiana epidermal cells, exposure to high light increases H 2 O 2 production in chloroplast stroma, cytosol and nuclei. Critically, over-expression of stromal ascorbate peroxidase (H 2 O 2 scavenger) or treatment with DCMU (photosynthesis inhibitor) attenuates nuclear H 2 O 2 accumulation and high light-responsive gene expression. Cytosolic ascorbate peroxidase over-expression has little effect on nuclear H 2 O 2 accumulation and high light-responsive gene expression. This is because the H 2 O 2 derives from a sub-population of chloroplasts closely associated with nuclei. Therefore, direct H 2 O 2 transfer from chloroplasts to nuclei, avoiding the cytosol, enables photosynthetic control over gene expression.Multiple plastid-derived signals have been proposed but not shown to move to the nucleus to promote plant acclimation to fluctuating light. Here the authors use a fluorescent hydrogen peroxide sensor to provide evidence that H 2 O 2 is transferred directly from chloroplasts to nuclei to control nuclear gene expression.

  19. One- or two-electron water oxidation, hydroxyl radical, or H_2O_2 evolution

    International Nuclear Information System (INIS)

    Siahrostami, Samira; Li, Guo-Ling; Viswanathan, Venkatasubramanian; Nørskov, Jens K.

    2017-01-01

    Electrochemical or photoelectrochemcial oxidation of water to form hydrogen peroxide (H_2O_2) or hydroxyl radicals (•OH) offers a very attractive route to water disinfection, and the first process could be the basis for a clean way to produce hydrogen peroxide. A major obstacle in the development of effective catalysts for these reactions is that the electrocatalyst must suppress the thermodynamically favored four-electron pathway leading to O_2 evolution. Here, we develop a thermochemical picture of the catalyst properties that determine selectivity toward the one, two, and four electron processes leading to •OH, H_2O_2, and O_2.

  20. Atmospheric H2O2 measurement: comparison of cold trap method with impinger bubbling method

    Science.gov (United States)

    Sakugawa, H.; Kaplan, I. R.

    1987-01-01

    Collection of atmospheric H2O2 was performed by a cold trap method using dry ice-acetone as the refrigerant. The air was drawn by a pump into a glass gas trap immersed in the dry ice-acetone slush in a dewar flask at a flow rate of 2.5 l min-1 for approximately 2 h. Collection efficiency was > 99% and negligible interferences by O3, SO2 or organic matter with the collected H2O2 in the trap were observed. This method was compared with the air impinger bubbling method which has been previously described (Kok et al., 1978a, b, Envir. Sci. Technol. 12, 1072-1080). The measured total peroxide (H2O2 + organic peroxide) values in a series of aim samples collected by the impinger bubbling method (0.06-3.7 ppb) were always higher than those obtained by the cold trap method (0.02-1.2 ppb). Laboratory experiments suggest that the difference in values between the two methods probably results from the aqueous phase generation of H2O2 and organic peroxide in the impinger solution by a reaction of atmospheric O3 with olefinic and aromatic compounds. If these O3-organic compound reactions which occur in the impinger also occur in aqueous droplets in the atmosphere, the process could be very important for aqueous phase generation of H2O2 in clouds and rainwater.

  1. Classification of H2O2 as a Neuromodulator that Regulates Striatal Dopamine Release on a Subsecond Time Scale

    Science.gov (United States)

    2012-01-01

    Here we review evidence that the reactive oxygen species, hydrogen peroxide (H2O2), meets the criteria for classification as a neuromodulator through its effects on striatal dopamine (DA) release. This evidence was obtained using fast-scan cyclic voltammetry to detect evoked DA release in striatal slices, along with whole-cell and fluorescence imaging to monitor cellular activity and H2O2 generation in striatal medium spiny neurons (MSNs). The data show that (1) exogenous H2O2 suppresses DA release in dorsal striatum and nucleus accumbens shell and the same effect is seen with elevation of endogenous H2O2 levels; (2) H2O2 is generated downstream from glutamatergic AMPA receptor activation in MSNs, but not DA axons; (3) generation of modulatory H2O2 is activity dependent; (4) H2O2 generated in MSNs diffuses to DA axons to cause transient DA release suppression by activating ATP-sensitive K+ (KATP) channels on DA axons; and (5) the amplitude of H2O2-dependent inhibition of DA release is attenuated by enzymatic degradation of H2O2, but the subsecond time course is determined by H2O2 diffusion rate and/or KATP-channel kinetics. In the dorsal striatum, neuromodulatory H2O2 is an intermediate in the regulation of DA release by the classical neurotransmitters glutamate and GABA, as well as other neuromodulators, including cannabinoids. However, modulatory actions of H2O2 occur in other regions and cell types, as well, consistent with the widespread expression of KATP and other H2O2-sensitive channels throughout the CNS. PMID:23259034

  2. A comparative study of the disinfection efficacy of H2O2/ferrate and UV/H2O2/ferrate processes on inactivation of Bacillus subtilis spores by response surface methodology for modeling and optimization.

    Science.gov (United States)

    Matin, Atiyeh Rajabi; Yousefzadeh, Samira; Ahmadi, Ehsan; Mahvi, Amirhossein; Alimohammadi, Mahmood; Aslani, Hassan; Nabizadeh, Ramin

    2018-04-03

    Although chlorination can inactivate most of the microorganisms in water but protozoan parasites like C. parvum oocysts and Giardia cysts can resist against it. Therefore, many researches have been conducted to find a novel method for water disinfection. Present study evaluated the synergistic effect of H2O2 and ferrate followed by UV radiation to inactivate Bacillus subtilis spores as surrogate microorganisms. Response surface methodology(RSM) was employed for the optimization for UV/H2O2/ferrate and H2O2/ferrate processes. By using central composite design(CCD), the effect of three main parameters including time, hydrogen peroxide, and ferrate concentrations was examined on process performance. The results showed that the combination of UV, H2O2 and ferrate was the most effective disinfection process in compare with when H2O2 and ferrate were used. This study indicated that by UV/H2O2/ferrate, about 5.2 log reductions of B. subtilis spores was inactivated at 9299 mg/l of H2O2 and 0.4 mg/l of ferrate concentrations after 57 min of contact time which was the optimum condition, but H2O2/ferrate can inactivate B. subtilis spores about 4.7 logs compare to the other process. Therefore, the results of this research demonstrated that UV/H2O2 /ferrate process is a promising process for spore inactivation and water disinfection. Copyright © 2018 Elsevier Ltd. All rights reserved.

  3. Alleviation of drought stress by mycorrhizas is related to increased root H2O2 efflux in trifoliate orange.

    Science.gov (United States)

    Huang, Yong-Ming; Zou, Ying-Ning; Wu, Qiang-Sheng

    2017-02-08

    The Non-invasive Micro-test Technique (NMT) is used to measure dynamic changes of specific ions/molecules non-invasively, but information about hydrogen peroxide (H 2 O 2 ) fluxes in different classes of roots by mycorrhiza is scarce in terms of NMT. Effects of Funneliformis mosseae on plant growth, H 2 O 2 , superoxide radical (O 2 ·- ), malondialdehyde (MDA) concentrations, and H 2 O 2 fluxes in the taproot (TR) and lateral roots (LRs) of trifoliate orange seedlings under well-watered (WW) and drought stress (DS) conditions were studied. DS strongly inhibited mycorrhizal colonization in the TR and LRs, whereas mycorrhizal inoculation significantly promoted plant growth and biomass production. H 2 O 2 , O 2 ·- , and MDA concentrations in leaves and roots were dramatically lower in mycorrhizal seedlings than in non-mycorrhizal seedlings under DS. Compared with non-mycorrhizal seedlings, mycorrhizal seedlings had relatively higher net root H 2 O 2 effluxes in the TR and LRs especially under WW, as well as significantly higher total root H 2 O 2 effluxes in the TR and LRs under WW and DS. Total root H 2 O 2 effluxes were significantly positively correlated with root colonization but negatively with root H 2 O 2 and MDA concentrations. It suggested that mycorrhizas induces more H 2 O 2 effluxes of the TR and LRs, thus, alleviating oxidative damage of DS in the host plant.

  4. Combined UV-C/H2O2-VUV processes for the treatment of an actual slaughterhouse wastewater.

    Science.gov (United States)

    Naderi, Kambiz Vaezzadeh; Bustillo-Lecompte, Ciro Fernando; Mehrvar, Mehrab; Abdekhodaie, Mohammad Jafar

    2017-05-04

    In this study, a three-factor, three-level Box-Behnken design with response surface methodology were used to maximize the TOC removal and minimize the H 2 O 2 residual in the effluent of the combined UV-C/H 2 O 2 -VUV system for the treatment of an actual slaughterhouse wastewater (SWW) collected from one of the meat processing plants in Ontario, Canada. The irradiation time and the initial concentrations of total organic carbon (TOC o ) and hydrogen peroxide (H 2 O 2o ) were the three predictors, as independent variables, studied in the design of experiments. The multiple response approach was used to obtain desirability response surfaces at the optimum factor settings. Subsequently, the optimum conditions to achieve the maximum percentage TOC removal of 46.19% and minimum H 2 O 2 residual of 1.05% were TOC o of 213 mg L -1 , H 2 O 2o of 450 mg L -1 , and irradiation time of 9 min. The attained optimal operating conditions were validated with a complementary test. Consequently, the TOC removal of 45.68% and H 2 O 2 residual of 1.03% were achieved experimentally, confirming the statistical model reliability. Three individual processes, VUV alone, VUV/H 2 O 2 , and UV-C/H 2 O 2 , were also evaluated to compare their performance for the treatment of the actual SWW using the optimum parameters obtained in combined UV-C/H 2 O 2 -VUV processes. Results confirmed that an adequate combination of the UV-C/H 2 O 2 -VUV processes is essential for an optimized TOC removal and H 2 O 2 residual. Finally, respirometry analyses were also performed to evaluate the biodegradability of the SWW and the BOD removal efficiency of the combined UV-C/H 2 O 2 -VUV processes.

  5. A KINETIC MODEL FOR H2O2/UV PROCESS IN A COMPLETELY MIXED BATCH REACTOR. (R825370C076)

    Science.gov (United States)

    A dynamic kinetic model for the advanced oxidation process (AOP) using hydrogen peroxide and ultraviolet irradiation (H2O2/UV) in a completely mixed batch reactor (CMBR) is developed. The model includes the known elementary chemical and photochemical reac...

  6. Cyclic mononucleotides modulate potassium and calcium flux responses to H2O2 in Arabidopsis roots

    KAUST Repository

    Ordoñ ez, Natalia Maria; Marondedze, Claudius; Thomas, Ludivine; Pasqualini, Stefania; Shabala, Lana; Shabala, Sergey; Gehring, Christoph A

    2014-01-01

    Cyclic mononucleotides are messengers in plant stress responses. Here we show that hydrogen peroxide (H2O2) induces rapid net K+-efflux and Ca2+-influx in Arabidopsis roots. Pre-treatment with either 10 μM cAMP or cGMP for 1 or 24 h does

  7. Sensitivity of mitochondrial DNA depleted ρ0 cells to H2O2 depends on the plasma membrane status.

    Science.gov (United States)

    Tomita, Kazuo; Kuwahara, Yoshikazu; Takashi, Yuko; Tsukahara, Takao; Kurimasa, Akihiro; Fukumoto, Manabu; Nishitani, Yoshihiro; Sato, Tomoaki

    2017-08-19

    To clarify the relationship between mitochondrial DNA (mtDNA)-depleted ρ0 cells and the cellular sensitivity to hydrogen peroxide (H 2 O 2 ), we established HeLa and SAS ρ0 cell lines and investigated their survival rate in H 2 O 2 , radical scavenging enzymes, plasma membrane potential status, and chronological change in intracellular H 2 O 2 amount under the existence of extracellular hydrogen peroxide compared with the parental cells. The results revealed that ρ0 cells had higher sensitivity to H 2 O 2 than their parental cells, even though the catalase activity of ρ0 cells was up-regulated, and the membrane potential of the ρ0 cells was lower than their parental cells. Furthermore, the internal H 2 O 2 amount significantly increased only in ρ0 cells after 50 μM H 2 O 2 treatment for 1 h. These results suggest that plasma membrane status of ρ0 cells may cause degradation, and the change could lead to enhanced membrane permeability to H 2 O 2 . As a consequence, ρ0 cells have a higher H 2 O 2 sensitivity than the parental cells. Copyright © 2017 Elsevier Inc. All rights reserved.

  8. Understanding the role of H(2)O(2) during pea seed germination: a combined proteomic and hormone profiling approach.

    Science.gov (United States)

    Barba-Espín, Gregorio; Diaz-Vivancos, Pedro; Job, Dominique; Belghazi, Maya; Job, Claudette; Hernández, José Antonio

    2011-11-01

    In a previous publication, we showed that the treatment of pea seeds in the presence of hydrogen peroxide (H(2)O(2)) increased germination performance as well as seedling growth. To gain insight into the mechanisms responsible for this behaviour, we have analysed the effect of treating mature pea seeds in the presence of 20 mm H(2)O(2) on several oxidative features such as protein carbonylation, endogenous H(2)O(2) and lipid peroxidation levels. We report that H(2)O(2) treatment of the pea seeds increased their endogenous H(2)O(2) content and caused carbonylation of storage proteins and of several metabolic enzymes. Under the same conditions, we also monitored the expression of two MAPK genes known to be activated by H(2)O(2) in adult pea plants. The expression of one of them, PsMAPK2, largely increased upon pea seed imbibition in H(2)O(2) , whereas no change could be observed in expression of the other, PsMAPK3. The levels of several phytohormones such as 1-aminocyclopropane carboxylic acid, indole-3-acetic acid and zeatin appeared to correlate with the measured oxidative indicators and with the expression of PsMAPK2. Globally, our results suggest a key role of H(2)O(2) in the coordination of pea seed germination, acting as a priming factor that involves specific changes at the proteome, transcriptome and hormonal levels. © 2011 Blackwell Publishing Ltd.

  9. MOLYBDENUM CATALYZED ACID PEROXIDE BLEACHING OF EUCALYPTUS KRAFT PULP

    Directory of Open Access Journals (Sweden)

    Marcos S. Rabelo

    2008-08-01

    Full Text Available Molybdenum catalyzed peroxide bleaching (PMo Stage consists of pulp treatment with hydrogen peroxide under acidic conditions in the presence of a molybdenum catalyst. Molybdenum is applied in catalytic doses (50-200 mg/kg pulp and may originate from various sources, including (NH46Mo7O24.4H2O, Na2MoO4.2H2O, siliconmolybdate, etc. This work is aimed at optimizing the PMo stage and evaluating its industrial application in the OAZDP sequence. Optimum PMo stage conditions for bleaching eucalyptus pulp were 90 ºC, pH 3.5, 2 h, 0.1 kg/adt Mo and 5 kg/adt H2O2. The PMo stage was more efficient to remove pulp hexenuronic acids than lignin. Its efficiency decreased with increasing pH in the range of 1.5-5.5, while it increased with increasing temperature and peroxide and molybdenum doses. The application of the PMo stage as replacement for the A-stage of the AZDP sequence significantly decreased chlorine dioxide demand. The PMo stage caused a decrease of 20-30% in the generation of organically bound chlorine. The quality parameters of the pulp produced during the PMo stage mill trial were comparable to those obtained with the reference A-stage.

  10. VUV photoionization cross sections of HO2, H2O2, and H2CO.

    Science.gov (United States)

    Dodson, Leah G; Shen, Linhan; Savee, John D; Eddingsaas, Nathan C; Welz, Oliver; Taatjes, Craig A; Osborn, David L; Sander, Stanley P; Okumura, Mitchio

    2015-02-26

    The absolute vacuum ultraviolet (VUV) photoionization spectra of the hydroperoxyl radical (HO2), hydrogen peroxide (H2O2), and formaldehyde (H2CO) have been measured from their first ionization thresholds to 12.008 eV. HO2, H2O2, and H2CO were generated from the oxidation of methanol initiated by pulsed-laser-photolysis of Cl2 in a low-pressure slow flow reactor. Reactants, intermediates, and products were detected by time-resolved multiplexed synchrotron photoionization mass spectrometry. Absolute concentrations were obtained from the time-dependent photoion signals by modeling the kinetics of the methanol oxidation chemistry. Photoionization cross sections were determined at several photon energies relative to the cross section of methanol, which was in turn determined relative to that of propene. These measurements were used to place relative photoionization spectra of HO2, H2O2, and H2CO on an absolute scale, resulting in absolute photoionization spectra.

  11. Lipid oxidation in human low-density lipoprotein induced by metmyoglobin/H2O2

    DEFF Research Database (Denmark)

    Witting, P K; Willhite, C A; Davies, Michael Jonathan

    1999-01-01

    Metmyoglobin (metMb) and H(2)O(2) can oxidize low-density lipoprotein (LDL) in vitro, and oxidized LDL may be atherogenic. The role of alpha-tocopherol (alpha-TOH) in LDL oxidation by peroxidases such as metMb is unclear. Herein, we show that during metMb/H(2)O(2)-induced oxidation of native LDL...... of CE-O(O)H is dependent on, and correlates with, LDL's alpha-TOH content, yet does not require preformed lipid hydroperoxides or H(2)O(2). This indicates that in native LDL alpha-TOH can act as a phase-transfer agent and alpha-TO(*) as a chain-transfer agent propagating LDL lipid peroxidation via...

  12. Quantifying Fenton reaction pathways driven by self-generated H2O2 on pyrite surfaces

    Science.gov (United States)

    Gil-Lozano, C.; Davila, A. F.; Losa-Adams, E.; Fairén, A. G.; Gago-Duport, L.

    2017-03-01

    Oxidation of pyrite (FeS2) plays a significant role in the redox cycling of iron and sulfur on Earth and is the primary cause of acid mine drainage (AMD). It has been established that this process involves multi-step electron-transfer reactions between surface defects and adsorbed O2 and H2O, releasing sulfoxy species (e.g., S2O32-, SO42-) and ferrous iron (Fe2+) to the solution and also producing intermediate by-products, such as hydrogen peroxide (H2O2) and other reactive oxygen species (ROS), however, our understanding of the kinetics of these transient species is still limited. We investigated the kinetics of H2O2 formation in aqueous suspensions of FeS2 microparticles by monitoring, in real time, the H2O2 and dissolved O2 concentration under oxic and anoxic conditions using amperometric microsensors. Additional spectroscopic and structural analyses were done to track the dependencies between the process of FeS2 dissolution and the degradation of H2O2 through the Fenton reaction. Based on our experimental results, we built a kinetic model which explains the observed trend of H2O2, showing that FeS2 dissolution can act as a natural Fenton reagent, influencing the oxidation of third-party species during the long term evolution of geochemical systems, even in oxygen-limited environments.

  13. Influence of γ-radiation on the reactivity of montmorillonite towards H2O2

    International Nuclear Information System (INIS)

    Holmboe, Michael; Jonsson, Mats; Wold, Susanna

    2012-01-01

    Compacted and water saturated bentonite will be used as an engineered barrier in deep geological repositories for radioactive waste in many countries. Due to the high dose rate of ionizing radiation outside the canisters holding the nuclear waste, radiolysis of the interlayer and pore water in the compacted bentonite is unavoidable. Upon reaction with the oxidizing and reducing species formed by water radiolysis (OH • , e − (aq) , H • , H 2 O 2 , H 2 , HO 2 • , H 3 O + ), the overall redox properties in the bentonite barrier may change. In this study the influence of γ-radiation on the structural Fe(II)/Fe Tot ratio in montmorillonite and its reactivity towards hydrogen peroxide (H 2 O 2 ) was investigated in parallel experiments. The results show that under anoxic conditions the structural Fe(II)/Fe Tot ratio of dispersed Montmorillonite increased from ≤3 to 25–30% after γ-doses comparable to repository conditions. Furthermore, a strong correlation between the structural Fe(II)/Fe Tot ratio and the H 2 O 2 decomposition rate in montmorillonite dispersions was found. This correlation was further verified in experiments with consecutive H 2 O 2 additions, since the structural Fe(II)/Fe Tot ratio was seen to decrease concordantly. This work shows that the structural iron in montmorillonite could be a sink for one of the major oxidants formed upon water radiolysis in the bentonite barrier, H 2 O 2 .

  14. Photolysis of H2O-H2O2 Mixtures: The Destruction of H2O2

    Science.gov (United States)

    Loeffler, M. J.; Fama, M.; Baragiola, R. A.; Carlson, R. W.

    2013-01-01

    We present laboratory results on the loss of H2O2 in solid H2O + H2O2 mixtures at temperatures between 21 and 145 K initiated by UV photolysis (193 nm). Using infrared spectroscopy and microbalance gravimetry, we measured the decrease of the 3.5 micrometer infrared absorption band during UV irradiation and obtained a photodestruction cross section that varies with temperature, being lowest at 70 K. We use our results, along with our previously measured H2O2 production rates via ionizing radiation and ion energy fluxes from the spacecraft to compare H2O2 creation and destruction at icy satellites by ions from their planetary magnetosphere and from solar UV photons. We conclude that, in many cases, H2O2 is not observed on icy satellite surfaces because the H2O2 photodestruction rate is much higher than the production rate via energetic particles, effectively keeping the H2O2 infrared signature at or below the noise level.

  15. TriPer, an optical probe tuned to the endoplasmic reticulum tracks changes in luminal H2O2.

    Science.gov (United States)

    Melo, Eduardo Pinho; Lopes, Carlos; Gollwitzer, Peter; Lortz, Stephan; Lenzen, Sigurd; Mehmeti, Ilir; Kaminski, Clemens F; Ron, David; Avezov, Edward

    2017-03-27

    The fate of hydrogen peroxide (H 2 O 2 ) in the endoplasmic reticulum (ER) has been inferred indirectly from the activity of ER-localized thiol oxidases and peroxiredoxins, in vitro, and the consequences of their genetic manipulation, in vivo. Over the years hints have suggested that glutathione, puzzlingly abundant in the ER lumen, might have a role in reducing the heavy burden of H 2 O 2 produced by the luminal enzymatic machinery for disulfide bond formation. However, limitations in existing organelle-targeted H 2 O 2 probes have rendered them inert in the thiol-oxidizing ER, precluding experimental follow-up of glutathione's role in ER H 2 O 2 metabolism. Here we report on the development of TriPer, a vital optical probe sensitive to changes in the concentration of H 2 O 2 in the thiol-oxidizing environment of the ER. Consistent with the hypothesized contribution of oxidative protein folding to H 2 O 2 production, ER-localized TriPer detected an increase in the luminal H 2 O 2 signal upon induction of pro-insulin (a disulfide-bonded protein of pancreatic β-cells), which was attenuated by the ectopic expression of catalase in the ER lumen. Interfering with glutathione production in the cytosol by buthionine sulfoximine (BSO) or enhancing its localized destruction by expression of the glutathione-degrading enzyme ChaC1 in the lumen of the ER further enhanced the luminal H 2 O 2 signal and eroded β-cell viability. A tri-cysteine system with a single peroxidatic thiol enables H 2 O 2 detection in oxidizing milieux such as that of the ER. Tracking ER H 2 O 2 in live pancreatic β-cells points to a role for glutathione in H 2 O 2 turnover.

  16. Characterization of titanium dioxide nanoparticles modified with polyacrylic acid and H2O2 for use as a novel radiosensitizer.

    Science.gov (United States)

    Morita, Kenta; Miyazaki, Serika; Numako, Chiya; Ikeno, Shinya; Sasaki, Ryohei; Nishimura, Yuya; Ogino, Chiaki; Kondo, Akihiko

    2016-12-01

    An induction of polyacrylic acid-modified titanium dioxide with hydrogen peroxide nanoparticles (PAA-TiO 2 /H 2 O 2 NPs) to a tumor exerted a therapeutic enhancement of X-ray irradiation in our previous study. To understand the mechanism of the radiosensitizing effect of PAA-TiO 2 /H 2 O 2 NPs, analytical observations that included DLS, FE-SEM, FT-IR, XAFS, and Raman spectrometry were performed. In addition, highly reactive oxygen species (hROS) which PAA-TiO 2 /H 2 O 2 NPs produced with X-ray irradiation were quantified by using a chemiluminescence method and a EPR spin-trapping method. We found that PAA-TiO 2 /H 2 O 2 NPs have almost the same characteristics as PAA-TiO 2 . Surprisingly, there were no significant differences in hROS generation. However, the existence of H 2 O 2 was confirmed in PAA-TiO 2 /H 2 O 2 NPs, because spontaneous hROS production was observed w/o X-ray irradiation. In addition, PAA-TiO 2 /H 2 O 2 NPs had a curious characteristic whereby they absorbed H 2 O 2 molecules and released them gradually into a liquid phase. Based on these results, the H 2 O 2 was continuously released from PAA-TiO 2 /H 2 O 2 NPs, and then released H 2 O 2 assumed to be functioned indirectly as a radiosensitizing factor.

  17. Antiapoptotic effects of caspase inhibitors on H2O2-treated lung cancer cells concerning oxidative stress and GSH.

    Science.gov (United States)

    Park, Woo Hyun

    2018-04-01

    Exogenous hydrogen peroxide (H 2 O 2 ) induces oxidative stress and apoptosis in cancer cells. This study evaluated the antiapoptotic effects of pan-caspase and caspase-3, -8, or -9 inhibitors on H 2 O 2 -treated Calu-6 and A549 lung cancer cells in relation to reactive oxygen species (ROS) and glutathione (GSH). Treatment with 50-500 μM H 2 O 2 inhibited the growth of Calu-6 and A549 cells at 24 h and induced apoptosis in these cells. All the tested caspase inhibitors significantly prevented cell death in H 2 O 2 -treated lung cancer cells. H 2 O 2 increased intracellular ROS levels, including that of O 2 ·- , at 1 and 24 h. It also increased the activity of catalase but decreased the activity of SOD. In addition, H 2 O 2 triggered GSH deletion in Calu-6 and A549 cells at 24 h. It reduced GSH levels in Calu-6 cells at 1 h but increased them at 24 h. Caspase inhibitors decreased O 2 ·- levels in H 2 O 2 -treated Calu-6 cells at 1 h and these inhibitors decreased ROS levels, including that of O 2 ·- , in H 2 O 2 -treated A549 cells at 24 h. Caspase inhibitors partially attenuated GSH depletion in H 2 O 2 -treated A549 cells and increased GSH levels in these cells at 24 h. However, the inhibitors did not affect GSH deletion and levels in Calu-6 cells at 24 h. In conclusion, H 2 O 2 induced caspase-dependent apoptosis in Calu-6 and A549 cells, which was accompanied by increases in ROS and GSH depletion. The antiapoptotic effects of caspase inhibitors were somewhat related to the suppression of H 2 O 2 -induced oxidative stress and GSH depletion.

  18. Study on the proliferation of human gastric cancer cell AGS by activation of EGFR in H2O2.

    Science.gov (United States)

    Wang, Q; Shen, W; Tao, G-Q; Sun, J; Shi, L-P

    2017-03-01

    This study is to investigate the effect of low concentration hydrogen peroxide (H2O2) on the proliferation of gastric cancer AGS cell line in vitro and the mechanism. AGS cells were treated with different low concentrations of H2O2 (1, 0.1, 0.01, and 0.001 μm) for 48 hours. The effect of H2O2 concentration gradient on the activity of AGS cell activities was detected by methyl thiazolyl tetrazolium (MTT) method. The expression of the epidermal growth factor receptor (EGFR) and its downstream signaling pathway extracellular signal-regulated kinase (ERK) protein in H2O2 was detected by Western blot method; moreover, the effect of H2O2 on intracellular reactive oxygen species (ROS) in AGS cells was observed under the fluorescence microscope and quantitative analysis by flow cytometry. The effect of H2O2 on the level of c-myc mRNA in AGS cells was also detected by reverse transcription polymerase chain reaction (RT-PCR). MTT detection results showed that 1 μm and 0.1 μm H2O2 at 48h can effectively promote the proliferation of AGS cells (pH2O2 treatment of AGS cells, the EGFR protein levels and ERK protein phosphorylation levels increased significantly (pH2O2 increased the intracellular reactive oxygen species (ROS). RT-PCR results showed the levels of c-myc mRNA in AGS cells treated with a low concentration of H2O2 were significantly increased (pH2O2 can significantly promote the proliferation of AGS cells by activating EGFR/ERK signaling pathway.

  19. Inhibition of PKR protects against H2O2-induced injury on neonatal cardiac myocytes by attenuating apoptosis and inflammation.

    Science.gov (United States)

    Wang, Yongyi; Men, Min; Xie, Bo; Shan, Jianggui; Wang, Chengxi; Liu, Jidong; Zheng, Hui; Yang, Wengang; Xue, Song; Guo, Changfa

    2016-12-08

    Reactive oxygenation species (ROS) generated from reperfusion results in cardiac injury through apoptosis and inflammation, while PKR has the ability to promote apoptosis and inflammation. The aim of the study was to investigate whether PKR is involved in hydrogen peroxide (H 2 O 2 ) induced neonatal cardiac myocytes (NCM) injury. In our study, NCM, when exposed to H 2 O 2 , resulted in persistent activation of PKR due to NCM endogenous RNA. Inhibition of PKR by 2-aminopurine (2-AP) or siRNA protected against H 2 O 2 induced apoptosis and injury. To elucidate the mechanism, we revealed that inhibition of PKR alleviated H 2 O 2 induced apoptosis companied by decreased caspase3/7 activity, BAX and caspase-3 expression. We also revealed that inhibition of PKR suppressed H 2 O 2 induced NFκB pathway and NLRP3 activation. Finally, we found ADAR1 mRNA and protein expression were both induced after H 2 O 2 treatment through STAT-2 dependent pathway. By gain and loss of ADAR1 expression, we confirmed ADAR1 modulated PKR activity. Therefore, we concluded inhibition of PKR protected against H 2 O 2 -induced injury by attenuating apoptosis and inflammation. A self-preservation mechanism existed in NCM that ADAR1 expression is induced by H 2 O 2 to limit PKR activation simultaneously. These findings identify a novel role for PKR/ADAR1 in myocardial reperfusion injury.

  20. H2O2 augments cytosolic calcium in nucleus tractus solitarii neurons via multiple voltage-gated calcium channels.

    Science.gov (United States)

    Ostrowski, Tim D; Dantzler, Heather A; Polo-Parada, Luis; Kline, David D

    2017-05-01

    Reactive oxygen species (ROS) play a profound role in cardiorespiratory function under normal physiological conditions and disease states. ROS can influence neuronal activity by altering various ion channels and transporters. Within the nucleus tractus solitarii (nTS), a vital brainstem area for cardiorespiratory control, hydrogen peroxide (H 2 O 2 ) induces sustained hyperexcitability following an initial depression of neuronal activity. The mechanism(s) associated with the delayed hyperexcitability are unknown. Here we evaluate the effect(s) of H 2 O 2 on cytosolic Ca 2+ (via fura-2 imaging) and voltage-dependent calcium currents in dissociated rat nTS neurons. H 2 O 2 perfusion (200 µM; 1 min) induced a delayed, slow, and moderate increase (~27%) in intracellular Ca 2+ concentration ([Ca 2+ ] i ). The H 2 O 2 -mediated increase in [Ca 2+ ] i prevailed during thapsigargin, excluding the endoplasmic reticulum as a Ca 2+ source. The effect, however, was abolished by removal of extracellular Ca 2+ or the addition of cadmium to the bath solution, suggesting voltage-gated Ca 2+ channels (VGCCs) as targets for H 2 O 2 modulation. Recording of the total voltage-dependent Ca 2+ current confirmed H 2 O 2 enhanced Ca 2+ entry. Blocking VGCC L, N, and P/Q subtypes decreased the number of cells and their calcium currents that respond to H 2 O 2 The number of responder cells to H 2 O 2 also decreased in the presence of dithiothreitol, suggesting the actions of H 2 O 2 were dependent on sulfhydryl oxidation. In summary, here, we have shown that H 2 O 2 increases [Ca 2+ ] i and its Ca 2+ currents, which is dependent on multiple VGCCs likely by oxidation of sulfhydryl groups. These processes presumably contribute to the previously observed delayed hyperexcitability of nTS neurons in in vitro brainstem slices. Copyright © 2017 the American Physiological Society.

  1. The Effect of H2O2 Interference in Chemical Oxygen Demand Removal During Advanced Oxidation Processes

    Directory of Open Access Journals (Sweden)

    Afsane Chavoshani

    2016-07-01

    Full Text Available Hydrogen peroxide (H2O2 is one of the most oxidants in AOPs. By H2O2 dissociation, hydroxyl radical with a standard oxidation potential of 2.7 is produced. It is reported H2O¬ residual in AOPs has been led to interference in chemical oxygen demand (COD test and it is able to hinder biological treatment of waste water. Because of high mixed organic load of solid waste leachate, this study investigated effect of H2O2 interference in COD removal from solid waste leachate. In this study effect of parameters such as pH (3,5,7,12, H2O2 dose (0.01, 0.02, 0.03, 0.04 mol l-1, and time reaction(10,20,30,40,50,60 min evaluated on H2O2 interference in COD removal from solid waste leachate. Optimum pH and concentration were 3 and 0.02 moll-1 respectively. With increasing reaction time, COD removal was increased. The false COD obtained between 0.49mg per 1mg of H2O2. The average of COD removal by H2O2 for 60 min was 6.57%. Also reaction rate of this process was 0.0029 min-1. The presence of H2O2 leads to overestimation of COD values after reaction time because it consumes the oxidation agent. The extent of H2O2 interference in COD analysis was proportional to the remaining H2O2 concentration at the moment of sampling.

  2. Protective effect of pomegranate seed oil against H2O2 -induced oxidative stress in cardiomyocytes

    Directory of Open Access Journals (Sweden)

    Mehdi Bihamta

    2017-01-01

    Full Text Available Objective: It has been well documented that oxidative stress is involved in the pathogenesis of cardiac diseases. Previous studies have shown that pomegranate seed oil (PSO has antioxidant properties. This study was designed to investigate probable protective effects of PSO against hydrogen peroxide (H2O2-induced damage in H9c2 cardiomyocytes.Materials and Methods: The cells were pretreated 24 hr with PSO 1 hr before exposure to 200 µM H2O2. Cell viability was evaluated using 3-(4,5-dimethylthiazol-2-yl-2,5-diphenyl tetrazolium (MTT assay. The level of reactive oxygen species (ROS and lipid peroxidation were measured by fluorimetric methods.Results: H2O2 significantly decreased cell viability which was accompanied by an increase in ROS production and lipid peroxidation and a decline in superoxide dismutase activity. Pretreatment with PSO increased viability of cardiomyocytes and decrease the elevated ROS production and lipid peroxidation. Also, PSO was able to restore superoxide dismutase activity.Conclusion: PSO has protective effect against oxidative stress-induced damage in cardiomyocytes and can be considered as a natural cardioprotective agent to prevent cardiovascular diseases.

  3. Inhibition of cyclophilin A suppresses H2O2-enhanced replication of HCMV through the p38 MAPK signaling pathway.

    Science.gov (United States)

    Xiao, Jun; Song, Xin; Deng, Jiang; Lv, Liping; Ma, Ping; Gao, Bo; Zhou, Xipeng; Zhang, Yanyu; Xu, Jinbo

    2016-09-01

    Human cytomegalovirus (HCMV) infection can be accelerated by intracellular and extracellular hydrogen peroxide (H2O2) stimulation, mediated by the activation of the p38 mitogen-activated protein kinase (MAPK) pathway. However, it remains unknown whether host gene expression is involved in H2O2-upregulated HCMV replication. Here, we show that the expression of the host gene, cyclophilin A (CyPA), could be facilitated by treatment with H2O2 in a dose-dependent manner. Experiments with CyPA-specific siRNA, or with cyclosporine A, an inhibitor of CyPA, confirmed that H2O2-mediated upregulation of HCMV replication is specifically mediated by upregulation of CyPA expression. Furthermore, depletion or inhibition of CyPA reduced H2O2-induced p38 activation, consistent with that of H2O2-upregulated HCMV lytic replication. These results show that H2O2 is capable of activating ROS-CyPA-p38 MAPK interactions to enhance HCMV replication.

  4. High concentrations of H2O2 make aerobic glycolysis energetically more favourable than cellular respiration.

    Directory of Open Access Journals (Sweden)

    Hamid R Molavian

    2016-08-01

    Full Text Available Since the original observation of the Warburg Effect in cancer cells, over eight decades ago, the major question of why aerobic glycolysis is favored over oxidative phosphorylation has remained unresolved. An understanding of this phenomenon may well be the key to the development of more effective cancer therapies. In this paper, we use a semi-empirical method to throw light on this puzzle. We show that aerobic glycolysis is in fact energetically more favorable than oxidative phosphorylation for concentrations of peroxide (H2O2 above some critical threshold value. The fundamental reason for this is the activation and high engagement of the pentose phosphate pathway (PPP in response to the production of reactive oxygen species H2O2 by mitochondria and the high concentration of H2O2 (produced by mitochondria and other sources. This makes oxidative phosphorylation an inefficient source of energy since it leads (despite high levels of ATP production to a concomitant high energy consumption in order to respond to the hazardous waste products resulting from cellular processes associated with this metabolic pathway. We also demonstrate that the high concentration of H2O2 results in an increased glucose consumption, and also increases the lactate production in the case of glycolysis.

  5. Strong enhancement of the chemiluminescence of the Cu(II)-H2O2 system on addition of carbon nitride quantum dots, and its application to the detection of H2O2 and glucose.

    Science.gov (United States)

    Hallaj, Tooba; Amjadi, Mohammad; Song, Zhenlun; Bagheri, Robabeh

    2017-12-19

    The authors report that carbon nitride quantum dots (CN QDs) exert a strong enhancing effect on the Cu(II)/H 2 O 2 chemiluminescent system. Chemiluminescence (CL) intensity is enhanced by CN QDs by a factor of ~75, while other carbon nanomaterials have a much weaker effect. The possible mechanism of the effect was evaluated by recording fluorescence and CL spectra and by examining the effect of various radical scavengers. Emitting species was found to be excited-state CN QDs that produce green CL peaking at 515 nm. The new CL system was applied to the sensitive detection of H 2 O 2 and glucose (via glucose oxidase-catalyzed formation of H 2 O 2 ) with detection limits (3σ) of 10 nM for H 2 O 2 and 100 nM for glucose. The probe was employed for glucose determination in human plasma samples with satisfactory results. Graphical abstract The effect of carbon nitride quantum dots (CN QDs) on Cu(II)-H 2 O 2 chemiluminescence reaction was studied and the new CL system was applied for sensitive detection of glucose based on the glucose oxidase (GOx)-catalyzed formation of H 2 O 2 .

  6. Reaction of ferric leghemoglobin with H2O2

    DEFF Research Database (Denmark)

    Moreau, S; Davies, M J; Puppo, A

    1995-01-01

    Ferric leghemoglobin in the presence of H2O2 is known to give rise to protein radicals, at least one of which is centred on a tyrosine residue. These radicals are quenched by at least two processes. The first one involves an intramolecular heme-protein cross-link probably involving the tyrosine r...

  7. Improved radiosensitive microcapsules using H2O2

    International Nuclear Information System (INIS)

    Harada, Satoshi; Ehara, Shigeru; Ishii, Keizo

    2010-01-01

    The radiation-induced releasing of the liquid-core of the microcapsules was improved using H 2 O 2 , which produced O 2 generation of H 2 O 2 after irradiation. Further, we tested whether these microcapsules enhanced the antitumor effects and decreased the adverse effects in vivo in C3He/J mice. The capsules were produced by spraying a mixture of 3.0% hyaluronic acid, 2.0% alginate, 3.0% H 2 O 2 , and 0.3 mmol of carboplatin on a mixture of 0.3 mol FeCl 2 and 0.15 mol CaCl 2 . The microcapsules were subcutaneously injected into MM46 tumors that had been inoculated in the left hind legs of C3He/J mice. The radiotherapy comprised tumor irradiation with 10 Gy or 20 Gy 60 Co. The antitumor effect of the microcapsules was tested by measuring tumor size and monitoring tumor growth. Three types of adverse effects were considered: fuzzy hair, loss of body weight, and death. The size of the capsule size was 23±2.4 μmφ and that of the liquid core, 20.2±2.2 μmφ. The injected microcapsules localized drugs around the tumor. The production of O 2 by radiation increased the release of carboplatin from the microcapsules. The antitumor effects of radiation, carboplatin, and released oxygen were synergistic. Localization of the carboplatin decreased its adverse effects. However, the H 2 O 2 caused ulceration of the skin in the treated area. The use of our microcapsules enhanced the antitumor effects and decreased the adverse effects of carboplatin. However, the skin-ulceration caused by H 2 O 2 must be considered before these microcapsules can be used clinically. (author)

  8. Descent with Modification: Thermal Reactions of Subsurface H2O2 of Relevance to Icy Satellites and Other Small Bodies

    Science.gov (United States)

    Hudson, Reggie L.; Loefler, Mark J.

    2012-01-01

    Laboratory experiments have demonstrated that magnetospheric radiation in the Jovian system drives reaction chemistry in ices at temperatures relevant to Europa and other icy satellites. Similarly, cosmic radiation (mainly protons) acting on cometary and interstellar ices can promote extensive chemical change. Among the products that have been identified in irradiated H20-ice is hydrogen peroxide (H202), which has been observed on Europa and is suspected on other worlds. Although the infrared spectra and radiation chemistry of H2O2-containing ices are well documented, the thermally-induced solid-phase chemistry of H2O2 is largely unknown. Therefore, in this presentation we report new laboratory results on reactions at 50 - 130 K in ices containing H2O2 and other molecules, both in the presence and absence of H2O. As an example of our results, we find that warming H2O + H2O2 + SO2 ices promotes SO2 oxidation to SO4(2-). We suspect that such redox chemistry may explain some of the observations related to the presence and distribution of H2O2 across Europa's surface as well as the lack of H2O2 on Ganymede and Callisto. If other molecules prove to be just as reactive with frozen H2O2 then it may explain why H2O2 has been absent from surfaces of many of the small icy bodies that are known to be exposed to ionizing radiation. Our results also have implications for the survival of H2O2 as it descends towards a subsurface ocean on Europa.

  9. Nitroxides protect horseradish peroxidase from H2O2-induced inactivation and modulate its catalase-like activity.

    Science.gov (United States)

    Samuni, Amram; Maimon, Eric; Goldstein, Sara

    2017-08-01

    Horseradish peroxidase (HRP) catalyzes H 2 O 2 dismutation while undergoing heme inactivation. The mechanism underlying this process has not been fully elucidated. The effects of nitroxides, which protect metmyoglobin and methemoglobin against H 2 O 2 -induced inactivation, have been investigated. HRP reaction with H 2 O 2 was studied by following H 2 O 2 depletion, O 2 evolution and heme spectral changes. Nitroxide concentration was followed by EPR spectroscopy, and its reactions with the oxidized heme species were studied using stopped-flow. Nitroxide protects HRP against H 2 O 2 -induced inactivation. The rate of H 2 O 2 dismutation in the presence of nitroxide obeys zero-order kinetics and increases as [nitroxide] increases. Nitroxide acts catalytically since its oxidized form is readily reduced to the nitroxide mainly by H 2 O 2 . The nitroxide efficacy follows the order 2,2,6,6-tetramethyl-piperidine-N-oxyl (TPO)>4-OH-TPO>3-carbamoyl proxyl>4-oxo-TPO, which correlates with the order of the rate constants of nitroxide reactions with compounds I, II, and III. Nitroxide catalytically protects HRP against inactivation induced by H 2 O 2 while modulating its catalase-like activity. The protective role of nitroxide at μM concentrations is attributed to its efficient oxidation by P940, which is the precursor of the inactivated form P670. Modeling the dismutation kinetics in the presence of nitroxide adequately fits the experimental data. In the absence of nitroxide the simulation fits the observed kinetics only if it does not include the formation of a Michaelis-Menten complex. Nitroxides catalytically protect heme proteins against inactivation induced by H 2 O 2 revealing an additional role played by nitroxide antioxidants in vivo. Copyright © 2017 Elsevier B.V. All rights reserved.

  10. Electrocatalytic reduction of H2O2 by Pt nanoparticles covalently bonded to thiolated carbon nanostructures

    International Nuclear Information System (INIS)

    You, Jung-Min; Kim, Daekun; Jeon, Seungwon

    2012-01-01

    Highlights: ► Novel thiolated carbon nanostructures – platinum nanoparticles [t-GO-C(O)-pt and t-MWCNT-C(O)-S-pt] have been synthesized, and [t-GO-C(O)-pt and t-MWCNT-C(O)-S-pt] denotes as t-GO-pt and t-MWCNT-Pt in manuscript, respectively. ► The modified electrode denoted as PDDA/t-GO-pt/GCE was used for the electrochemical determination of H 2 O 2 for the first time. ► The results show that PDDA/t-GO-pt nanoparticles have the promising potential as the basic unit of the electrochemical biosensors for the detection of H 2 O 2 . ► The proposed H 2 O 2 biosensors exhibited wide linear ranges and low detection limits, giving fast responses within 10 s. - Abstract: Glassy carbon electrodes were coated with thiolated carbon nanostructures – multi-walled carbon nanotubes and graphene oxide. The subsequent covalent addition of platinum nanoparticles and coating with poly(diallydimethylammonium chloride) resulted in biosensors that detected hydrogen peroxide through its electrocatalytic reduction. The sensors were easily and quickly prepared and showed improved sensitivity to the electrocatalytic reduction of H 2 O 2 . The Pt nanoparticles covalently bonded to the thiolated carbon nanostructures were characterized by transmission electron microscopy, X-ray photoelectron spectroscopy, and energy dispersive X-ray spectroscopy. Cyclic voltammetry and amperometry were used to characterize the biosensors’ performances. The sensors exhibited wide linear ranges and low detection limits, giving fast responses within 10 s, thus demonstrating their potential for use in H 2 O 2 analysis.

  11. CodY Regulates Thiol Peroxidase Expression as Part of the Pneumococcal Defense Mechanism against H2O2 Stress.

    Science.gov (United States)

    Hajaj, Barak; Yesilkaya, Hasan; Shafeeq, Sulman; Zhi, Xiangyun; Benisty, Rachel; Tchalah, Shiran; Kuipers, Oscar P; Porat, Nurith

    2017-01-01

    Streptococcus pneumoniae is a facultative anaerobic pathogen. Although it maintains fermentative metabolism, during aerobic growth pneumococci produce high levels of H 2 O 2 , which can have adverse effects on cell viability and DNA, and influence pneumococcal interaction with its host. The pneumococcus is unusual in its dealing with toxic reactive oxygen species (ROS) in that it neither has catalase nor the global regulators of peroxide stress resistance. Previously, we identified pneumococcal thiol peroxidase (TpxD) as the key enzyme for enzymatic removal of H 2 O 2 , and showed that TpxD synthesis is up-regulated upon exposure to H 2 O 2 . This study aimed to reveal the mechanism controlling TpxD expression under H 2 O 2 stress. We hypothesize that H 2 O 2 activates a transcription factor which in turn up-regulates tpxD expression. Microarray analysis revealed a pneumococcal global transcriptional response to H 2 O 2 . Mutation of tpxD abolished H 2 O 2 -mediated response to high H 2 O 2 levels, signifying the need for an active TpxD under oxidative stress conditions. Bioinformatic tools, applied to search for a transcription factor modulating tpxD expression, pointed toward CodY as a potential candidate. Indeed, a putative 15-bp consensus CodY binding site was found in the proximal region of tpxD- coding sequence. Binding of CodY to this site was confirmed by EMSA, and genetic engineering techniques demonstrated that this site is essential for TpxD up-regulation under H 2 O 2 stress. Furthermore, tpxD expression was reduced in a Δ codY mutant. These data indicate that CodY is an activator of tpxD expression, triggering its up-regulation under H 2 O 2 stress. In addition we show that H 2 O 2 specifically oxidizes the 2 CodY cysteines. This oxidation may trigger a conformational change in CodY, resulting in enhanced binding to DNA. A schematic model illustrating the contribution of TpxD and CodY to pneumococcal global transcriptional response to H 2 O 2 is

  12. Preparation of a Two-Photon Fluorescent Probe for Imaging H2O2 in Lysosomes in Living Cells and Tissues.

    Science.gov (United States)

    Ren, Mingguang; Deng, Beibei; Kong, Xiuqi; Tang, Yonghe; Lin, Weiying

    2017-01-01

    Hydrogen peroxide (H 2 O 2 ) plays important roles in many physiological and pathological processes. At the cellular organelle level, the abnormal concentrations of H 2 O 2 in the lysosomes may cause redox imbalance and the loss of the critical functions of the lysosomes. Herein, we describe the preparation of a potent lysosome-targeted two-photon fluorescent probe (Lyso-HP) for the detection of H 2 O 2 in the lysosomes in the living cells. This unique fluorescent probe can also be employed to effectively detect H 2 O 2 in the living tissues using two-photon fluorescence microscopy.

  13. Effect of H2O2 application during ‘Grande naine’-Mycosphaerella fijiensis interaction

    Directory of Open Access Journals (Sweden)

    Milady Mendoza-Rodríguez

    2017-11-01

    Full Text Available In Musa spp. considerable economical lost are cause by Mycosphaerella fijiensis infection around the world, that is why the study of the pathosystem constitute a priority. However, the main mechanisms activated in banana after infection are still unknown and are a limitation for a better understanding of this complex relationship. The objective of this study was to determine the effect of hydrogen peroxide (H2O2 application, on leaves of ‘Grande naine’ plants, on black leaf streak disease development (BLSD. For this purpose, the first three open leaves of banana plants were inoculated with the monoascosporic isolate of M. fijiensis CCIBP-Pf-83. At three days post-inoculation different H2O2 concentrations (10, 20, 30 and 40 mmol l-1 were sprayed to these plants as well as to non-inoculated ones. During the time course of the experiment for inoculated, sprayed plants and for control plants (infected with M. fijiensis epidemiological variables as well as the area of necrotic lesions at 49 dpi were measured. The findings of this analysis showed that the early application of H2O2 have influence on the BLSD development.   Keywords: banana, black leaf streak disease, hemibiotrophic, hydrogen peroxide

  14. Phosphate-Catalyzed Hydrogen Peroxide Formation from Agar, Gellan, and κ-Carrageenan and Recovery of Microbial Cultivability via Catalase and Pyruvate.

    Science.gov (United States)

    Kawasaki, Kosei; Kamagata, Yoichi

    2017-11-01

    Previously, we reported that when agar is autoclaved with phosphate buffer, hydrogen peroxide (H 2 O 2 ) is formed in the resulting medium (PT medium), and the colony count on the medium inoculated with environmental samples becomes much lower than that on a medium in which agar and phosphate are autoclaved separately (PS medium) (T. Tanaka et al., Appl Environ Microbiol 80:7659-7666, 2014, https://doi.org/10.1128/AEM.02741-14). However, the physicochemical mechanisms underlying this observation remain largely unknown. Here, we determined the factors affecting H 2 O 2 formation in agar. The H 2 O 2 formation was pH dependent: H 2 O 2 was formed at high concentrations in an alkaline or neutral phosphate buffer but not in an acidic buffer. Ammonium ions enhanced H 2 O 2 formation, implying the involvement of the Maillard reaction catalyzed by phosphate. We found that other gelling agents (e.g., gellan and κ-carrageenan) also produced H 2 O 2 after being autoclaved with phosphate. We then examined the cultivability of microorganisms from a fresh-water sample to test whether catalase and pyruvate, known as H 2 O 2 scavengers, are effective in yielding high colony counts. The colony count on PT medium was only 5.7% of that on PS medium. Catalase treatment effectively restored the colony count of PT medium (to 106% of that on PS medium). In contrast, pyruvate was not as effective as catalase: the colony count on sodium pyruvate-supplemented PT medium was 58% of that on PS medium. Given that both catalase and pyruvate can remove H 2 O 2 from PT medium, these observations indicate that although H 2 O 2 is the main cause of reduced colony count on PT medium, other unknown growth-inhibiting substances that cannot be removed by pyruvate (but can be by catalase) may also be involved. IMPORTANCE The majority of bacteria in natural environments are recalcitrant to laboratory culture techniques. Previously, we demonstrated that one reason for this is the formation of high H 2 O

  15. Cyclic mononucleotides modulate potassium and calcium flux responses to H2O2 in Arabidopsis roots

    KAUST Repository

    Ordoñez, Natalia Maria

    2014-02-13

    Cyclic mononucleotides are messengers in plant stress responses. Here we show that hydrogen peroxide (H2O2) induces rapid net K+-efflux and Ca2+-influx in Arabidopsis roots. Pre-treatment with either 10 μM cAMP or cGMP for 1 or 24 h does significantly reduce net K+-leakage and Ca2+-influx, and in the case of the K+-fluxes, the cell permeant cyclic mononucleotides are more effective. We also examined the effect of 10 μM of the cell permeant 8-Br-cGMP on the Arabidopsis microsomal proteome and noted a specific increase in proteins with a role in stress responses and ion transport, suggesting that cGMP is sufficient to directly and/or indirectly induce complex adaptive changes to cellular stresses induced by H2O2. © 2014 Federation of European Biochemical Societies. Published by Elsevier B.V. All rights reserved.

  16. Photogeneration of H2O2 in Water-Swollen SPEEK/PVA Polymer Films.

    Science.gov (United States)

    Lockhart, PaviElle; Little, Brian K; Slaten, B L; Mills, G

    2016-06-09

    Efficient reduction of O2 took place via illumination with 350 nm photons of cross-linked films containing a blend of sulfonated poly(ether etherketone) and poly(vinyl alcohol) in contact with air-saturated aqueous solutions. Swelling of the solid macromolecular matrices in H2O enabled O2 diffusion into the films and also continuous extraction of the photogenerated H2O2, which was the basis for a method that allowed quantification of the product. Peroxide formed with similar efficiencies in films containing sulfonated polyketones prepared from different precursors and the initial photochemical process was found to be the rate-determining step. Generation of H2O2 was most proficient in the range of 4.9 ≤ pH ≤ 8 with a quantum yield of 0.2, which was 10 times higher than the efficiencies determined for solutions of the polymer blend. Increases in temperature as well as [O2] in solution were factors that enhanced the H2O2 generation. H2O2 quantum yields as high as 0.6 were achieved in H2O/CH3CN mixtures with low water concentrations, but peroxide no longer formed when film swelling was suppressed. A mechanism involving reduction of O2 by photogenerated α-hydroxy radicals from the polyketone in competition with second-order radical decay processes explains the kinetic features. Higher yields result from the films because cross-links present in them hinder diffusion of the radicals, limiting their decay and enhancing the oxygen reduction pathway.

  17. Determine the Intensity of UV Radiation and H2O2 on the Removal of Methylene Blue from Synthetic Wastewater

    Directory of Open Access Journals (Sweden)

    Mehdi Hosseini

    2015-03-01

    Full Text Available Background: There is a tremendous amount of color in textile wastewater that discharge it to the environment can cause a lot of environmental problems. The aim of this study is to evaluate the photocatalytic process UV/H2O2 to remove methylene blue dye from synthetic wastewater. Methods: UVC lamp was used as light source. In this study the effect of UV light intensity, irradiation distance, hydrogen peroxide concentration, and reaction time on the removal of methylene blue from aqueous solutions were studied. Data was analyzed by SPSS 18 and excel software. Results: The result showed that with increasing concentration of hydrogen peroxide, the color removal increases. Color removal changes were negligible at H2O2 concentration more than 5 mM. After 10 minutes reaction time at H2O2 concentration of 1 mm, efficiency of UVC/H2O2 is equal to 36.6%. Whilst at 5 mM concentration, removal efficiency is 89.2%. By increasing intensity of UV radiation, dye removal measure is also was increased, as the highest percentage of dye removal was obtained at 24 W radiation intensity. Conclusion: in present study, type of radiation and measure of hydrogen peroxide were the main factors in removal of methylene blue. Due to high efficiency of UVC/H2O2 process in removal of dye from aqueous solution, this method can use as an efficient process for removal of dye.

  18. Protective effect of bone morphogenetic protein 6 on RPE cells injury caused by H2O2

    Directory of Open Access Journals (Sweden)

    Li Chen

    2016-01-01

    Full Text Available AIM:To investigate the effect of bone morphogenetic protein 6(BMP-6on cellular morphology, proliferation and apoptosis of retinal pigment epithelial cells(ARPE-19incubated in hydrogen peroxide(H2O2. METHODS:ARPE-19 cells were cultured conventionally and divided into four groups. One group was untreated as blank group, the other three groups were incubated in 75μm/L H2O2, 150ng/mLBMP-6 or75μm/L H2O2+150ng/mL BMP-6. All the groups were incubated for 3h, 6h, 9h and 12h. We tested the cell viabilitity by MTT. We used flow cytometry to test the cell cycle and cell apoptosis.RESULTS:H2O2 significantly decreased the cell activity in time-dependent manner. The activity of cells with BMP-6+H2O2 was higher H2O2 group, and the differences between the two groups at 3h and 6h were significant(P2O2, while the cells with BMP-6 were less cell detachment and apoptosis. CONCLUSION:BMP-6 has protective effects on RPE cells from oxidative stress in certain extent.

  19. Bactericidal Effect of Photolysis of H2O2 in Combination with Sonolysis of Water via Hydroxyl Radical Generation.

    Directory of Open Access Journals (Sweden)

    Hong Sheng

    Full Text Available The bactericidal effect of hydroxyl radical (·OH generated by combination of photolysis of hydrogen peroxide (H2O2 and sonolysis of water was examined under the condition in which the yield of ·OH increased additively when H2O2 aqueous solution was concomitantly irradiated with laser and ultrasound. The suspension of Staphylococcus aureus mixed with the different concentrations of H2O2 was irradiated simultaneously with a laser light (wavelength: 405 nm, irradiance: 46 and 91 mW/cm2 and ultrasound (power: 30 w, frequency: 1.65 MHz at 20 ± 1°C of the water bulk temperature for 2 min. The combination of laser and ultrasound irradiation significantly reduced the viable bacterial count in comparison with the laser irradiation of H2O2 alone. By contrast, the ultrasound irradiation alone exerted almost no bactericidal effect. These results suggested that the combination effect of photolysis of H2O2 and sonolysis of water on bactericidal activity was synergistic. A multi-way analysis of variance also revealed that the interaction of H2O2 concentration, laser power and ultrasound irradiation significantly affected the bactericidal activity. Since the result of oxidative DNA damage evaluation demonstrated that the combination of laser and ultrasound irradiation significantly induced oxidative damage of bacterial DNA in comparison with the laser irradiation of H2O2 alone, it was suggested that the combination effect of photolysis of H2O2 and sonolysis of water on bactericidal activity would be exerted via oxidative damage of cellular components such as DNA.

  20. Bactericidal Effect of Photolysis of H2O2 in Combination with Sonolysis of Water via Hydroxyl Radical Generation.

    Science.gov (United States)

    Sheng, Hong; Nakamura, Keisuke; Kanno, Taro; Sasaki, Keiichi; Niwano, Yoshimi

    2015-01-01

    The bactericidal effect of hydroxyl radical (·OH) generated by combination of photolysis of hydrogen peroxide (H2O2) and sonolysis of water was examined under the condition in which the yield of ·OH increased additively when H2O2 aqueous solution was concomitantly irradiated with laser and ultrasound. The suspension of Staphylococcus aureus mixed with the different concentrations of H2O2 was irradiated simultaneously with a laser light (wavelength: 405 nm, irradiance: 46 and 91 mW/cm2) and ultrasound (power: 30 w, frequency: 1.65 MHz) at 20 ± 1°C of the water bulk temperature for 2 min. The combination of laser and ultrasound irradiation significantly reduced the viable bacterial count in comparison with the laser irradiation of H2O2 alone. By contrast, the ultrasound irradiation alone exerted almost no bactericidal effect. These results suggested that the combination effect of photolysis of H2O2 and sonolysis of water on bactericidal activity was synergistic. A multi-way analysis of variance also revealed that the interaction of H2O2 concentration, laser power and ultrasound irradiation significantly affected the bactericidal activity. Since the result of oxidative DNA damage evaluation demonstrated that the combination of laser and ultrasound irradiation significantly induced oxidative damage of bacterial DNA in comparison with the laser irradiation of H2O2 alone, it was suggested that the combination effect of photolysis of H2O2 and sonolysis of water on bactericidal activity would be exerted via oxidative damage of cellular components such as DNA.

  1. Removal of phenolic endocrine disrupting compounds from waste activated sludge using UV, H2O2, and UV/H2O2 oxidation processes: Effects of reaction conditions and sludge matrix

    International Nuclear Information System (INIS)

    Zhang, Ai; Li, Yongmei

    2014-01-01

    Removal of six phenolic endocrine disrupting compounds (EDCs) (estrone, 17β-estradiol, 17α-ethinylestradiol, estriol, bisphenol A, and 4-nonylphenols) from waste activated sludge (WAS) was investigated using ultraviolet light (UV), hydrogen peroxide (H 2 O 2 ), and the combined UV/H 2 O 2 processes. Effects of initial EDC concentration, H 2 O 2 dosage, and pH value were investigated. Particularly, the effects of 11 metal ions and humic acid (HA) contained in a sludge matrix on EDC degradation were evaluated. A pseudo-first-order kinetic model was used to describe the EDC degradation during UV, H 2 O 2 , and UV/H 2 O 2 treatments of WAS. The results showed that the degradation of the 6 EDCs during all the three oxidation processes fitted well with pseudo-first-order kinetics. Compared with the sole UV irradiation or H 2 O 2 oxidation process, UV/H 2 O 2 treatment was much more effective for both EDC degradation and WAS solubilization. Under their optimal conditions, the EDC degradation rate constants during UV/H 2 O 2 oxidation were 45–197 times greater than those during UV irradiation and 11–53 times greater than those during H 2 O 2 oxidation. High dosage of H 2 O 2 and low pH were favorable for the degradation of EDCs. Under the conditions of pH = 3, UV wavelength = 253.7 nm, UV fluence rate = 0.069 mW cm −2 , and H 2 O 2 dosage = 0.5 mol L −1 , the removal efficiencies of E1, E2, EE2, E3, BPA, and NP in 2 min were 97%, 92%, 95%, 94%, 89%, and 67%, respectively. The hydroxyl radical (·OH) was proved to take the most important role for the removal of EDCs. Metal ions in sludge could facilitate the removal of EDCs during UV/H 2 O 2 oxidation. Fe, Ag, and Cu ions had more obvious effects compared with other metal ions. The overall role of HA was dependent on the balance between its competition as organics and its catalysis/photosensitization effects. These indicate that the sludge matrix plays an important role in the degradation of EDCs. - Highlights:

  2. H2O2 assisted room temperature oxidation of Ti2C MXene for Li-ion battery anodes

    KAUST Repository

    Ahmed, Bilal

    2016-03-08

    Herein we demonstrate that a prominent member of the MXene family, Ti2C, undergoes surface oxidation at room temperature when treated with hydrogen peroxide (H2O2). The H2O2 treatment results in opening up of MXene sheets and formation of TiO2 nanocrystals on their surface, which is evidenced by the high surface area of H2O2 treated MXene and X-ray diffraction (XRD) analysis. We show that the reaction time and the amount of hydrogen peroxide used are the limiting factors, which determine the morphology and composition of the final product. Furthermore, it is shown that the performance of H2O2 treated MXene as an anode material in Li ion batteries (LIBs) was significantly improved as compared to as-prepared MXenes. For instance, after 50 charge/discharge cycles, specific discharge capacities of 389 mA h g−1, 337 mA h g−1 and 297 mA h g−1 were obtained for H2O2 treated MXene at current densities of 100 mA g−1, 500 mA g−1 and 1000 mA g−1, respectively. In addition, when tested at a very high current density, such as 5000 mA g−1, the H2O2 treated MXene showed a specific capacity of 150 mA h g−1 and excellent rate capability. These results clearly demonstrate that H2O2 treatment of Ti2C MXene improves MXene properties in energy storage applications, such as Li ion batteries or capacitors.

  3. H2O2 assisted room temperature oxidation of Ti2C MXene for Li-ion battery anodes

    KAUST Repository

    Ahmed, Bilal; Anjum, Dalaver H.; Hedhili, Mohamed N.; Gogotsi, Yury; Alshareef, Husam N.

    2016-01-01

    Herein we demonstrate that a prominent member of the MXene family, Ti2C, undergoes surface oxidation at room temperature when treated with hydrogen peroxide (H2O2). The H2O2 treatment results in opening up of MXene sheets and formation of TiO2 nanocrystals on their surface, which is evidenced by the high surface area of H2O2 treated MXene and X-ray diffraction (XRD) analysis. We show that the reaction time and the amount of hydrogen peroxide used are the limiting factors, which determine the morphology and composition of the final product. Furthermore, it is shown that the performance of H2O2 treated MXene as an anode material in Li ion batteries (LIBs) was significantly improved as compared to as-prepared MXenes. For instance, after 50 charge/discharge cycles, specific discharge capacities of 389 mA h g−1, 337 mA h g−1 and 297 mA h g−1 were obtained for H2O2 treated MXene at current densities of 100 mA g−1, 500 mA g−1 and 1000 mA g−1, respectively. In addition, when tested at a very high current density, such as 5000 mA g−1, the H2O2 treated MXene showed a specific capacity of 150 mA h g−1 and excellent rate capability. These results clearly demonstrate that H2O2 treatment of Ti2C MXene improves MXene properties in energy storage applications, such as Li ion batteries or capacitors.

  4. Does residual H2O2 result in inhibitory effect on enhanced anaerobic digestion of sludge pretreated by microwave-H2O2 pretreatment process?

    Science.gov (United States)

    Liu, Jibao; Jia, Ruilai; Wang, Yawei; Wei, Yuansong; Zhang, Junya; Wang, Rui; Cai, Xing

    2017-04-01

    This study investigated the effects of residual H 2 O 2 on hydrolysis-acidification and methanogenesis stages of anaerobic digestion after microwave-H 2 O 2 (MW-H 2 O 2 ) pretreatment of waste activated sludge (WAS). Results showed that high sludge solubilization at 35-45 % was achieved after pretreatment, while large amounts of residual H 2 O 2 remained and refractory compounds were thus generated with high dosage of H 2 O 2 (0.6 g H 2 O 2 /g total solids (TS), 1.0 g H 2 O 2 /g TS) pretreatment. The residual H 2 O 2 not only inhibited hydrolysis-acidification stage mildly, such as hydrolase activity, but also had acute toxic effect on methanogens, resulting in long lag phase, low methane yield rate, and no increase of cumulative methane production during the 30-day BMP tests. When the low dosage of H 2 O 2 at 0.2 g H 2 O 2 /g TS was used in MW-H 2 O 2 pretreatment, sludge anaerobic digestion was significantly enhanced. The cumulative methane production increased by 29.02 %, but still with a lag phase of 1.0 day. With removing the residual H 2 O 2 by catalase, the initial lag phase of hydrolysis-acidification stage decreased from 1.0 to 0.5 day.

  5. Chronic hypoxia promotes pulmonary artery endothelial cell proliferation through H2O2-induced 5-lipoxygenase.

    Directory of Open Access Journals (Sweden)

    Kristi M Porter

    Full Text Available Pulmonary Hypertension (PH is a progressive disorder characterized by endothelial dysfunction and proliferation. Hypoxia induces PH by increasing vascular remodeling. A potential mediator in hypoxia-induced PH development is arachidonate 5-Lipoxygenase (ALOX5. While ALOX5 metabolites have been shown to promote pulmonary vasoconstriction and endothelial cell proliferation, the contribution of ALOX5 to hypoxia-induced proliferation remains unknown. We hypothesize that hypoxia exposure stimulates HPAEC proliferation by increasing ALOX5 expression and activity. To test this, human pulmonary artery endothelial cells (HPAEC were cultured under normoxic (21% O2 or hypoxic (1% O2 conditions for 24-, 48-, or 72 hours. In a subset of cells, the ALOX5 inhibitor, zileuton, or the 5-lipoxygenase activating protein inhibitor, MK-886, was administered during hypoxia exposure. ALOX5 expression was measured by qRT-PCR and western blot and HPAEC proliferation was assessed. Our results demonstrate that 24 and 48 hours of hypoxia exposure have no effect on HPAEC proliferation or ALOX5 expression. Seventy two hours of hypoxia significantly increases HPAEC ALOX5 expression, hydrogen peroxide (H2O2 release, and HPAEC proliferation. We also demonstrate that targeted ALOX5 gene silencing or inhibition of the ALOX5 pathway by pharmacological blockade attenuates hypoxia-induced HPAEC proliferation. Furthermore, our findings indicate that hypoxia-induced increases in cell proliferation and ALOX5 expression are dependent on H2O2 production, as administration of the antioxidant PEG-catalase blocks these effects and addition of H2O2 to HPAEC promotes proliferation. Overall, these studies indicate that hypoxia exposure induces HPAEC proliferation by activating the ALOX5 pathway via the generation of H2O2.

  6. Catalase and ascorbate peroxidase-representative H2O2-detoxifying heme enzymes in plants.

    Science.gov (United States)

    Anjum, Naser A; Sharma, Pallavi; Gill, Sarvajeet S; Hasanuzzaman, Mirza; Khan, Ekhlaque A; Kachhap, Kiran; Mohamed, Amal A; Thangavel, Palaniswamy; Devi, Gurumayum Devmanjuri; Vasudhevan, Palanisamy; Sofo, Adriano; Khan, Nafees A; Misra, Amarendra Narayan; Lukatkin, Alexander S; Singh, Harminder Pal; Pereira, Eduarda; Tuteja, Narendra

    2016-10-01

    Plants have to counteract unavoidable stress-caused anomalies such as oxidative stress to sustain their lives and serve heterotrophic organisms including humans. Among major enzymatic antioxidants, catalase (CAT; EC 1.11.1.6) and ascorbate peroxidase (APX; EC 1.11.1.11) are representative heme enzymes meant for metabolizing stress-provoked reactive oxygen species (ROS; such as H2O2) and controlling their potential impacts on cellular metabolism and functions. CAT mainly occurs in peroxisomes and catalyzes the dismutation reaction without requiring any reductant; whereas, APX has a higher affinity for H2O2 and utilizes ascorbate (AsA) as specific electron donor for the reduction of H2O2 into H2O in organelles including chloroplasts, cytosol, mitochondria, and peroxisomes. Literature is extensive on the glutathione-associated H2O2-metabolizing systems in plants. However, discussion is meager or scattered in the literature available on the biochemical and genomic characterization as well as techniques for the assays of CAT and APX and their modulation in plants under abiotic stresses. This paper aims (a) to introduce oxidative stress-causative factors and highlights their relationship with abiotic stresses in plants; (b) to overview structure, occurrence, and significance of CAT and APX in plants; (c) to summarize the principles of current technologies used to assay CAT and APX in plants; (d) to appraise available literature on the modulation of CAT and APX in plants under major abiotic stresses; and finally, (e) to consider a brief cross-talk on the CAT and APX, and this also highlights the aspects unexplored so far.

  7. Hypericin from St. John’s Wort (hypericum perforatum) as a novel natural fluorophore for chemiluminescence reaction of bis (2,4,6-trichlorophenyl) oxalate–H2O2–imidazole and quenching effect of some natural lipophilic hydrogen peroxide scavengers

    International Nuclear Information System (INIS)

    Kazemi, Sayed Yahya; Abedirad, Seyed Mohammad; Zali, Seyed Hassan; Amiri, Mohadeseh

    2012-01-01

    Hypericin (HYP) molecule is a natural photoactive pigment, which plays a role as an effective photoreceptor in some plants of the Hypericum species (the most common of which is Saint John’s Wort) and some insect species. The present work deals with the first attempt to the study of peroxyoxalate chemiluminescence (POCL) system in the presense of HYP as a natural fluorophore. Reaction of bis (2,4,6-trichlorophenyl) oxalate(TCPO)–H 2 O 2 –imidazole can transfer energy to a HYP via formation of dioxetane through the chemically initiated electron exchange luminescence (CIEEL) mechanism and can emits a very intense red light. The effects of HYP, hydrogen peroxide, TCPO and imidazole concentrations on kinetic chemiluminescence parameters were also studied. These parameters including rise and fall rate constant for the chemiluminescence burst, theoretical and experimental maximum intensity, theoretical and experimental time to reach maximum intensity and total light yield emission were evaluated by using a pooled intermediate model for a non-linear least-squares curve fitting program, KINFIT. Moreover, quenching effect of two lipophilic natural antioxidant, Quercetin and β-carotene on it system was also investigated. The measurable concentration range of 7×10 −6 M to 7.5×10 −5 M of antioxidants were evaluated from the proper Stern–Volmer plots with satisfactory RSD% and corresponding detection limits of 2.2×10 −6 and 3.7×10 −6 for β-carotene and quercetin respectively. - Highlights: ► Red fluorophores may therefore chemiluminescence more intensely than other commonly chemiluminophores and emits light in longer wavelengths. ► Hypericin from St. John’s wort (hypericum perforatum) as natural red fluorophore for peroxyoxalate chemiluminescence was introduced. ► Quenching effect of two antioxidant, quercetin and β-carotene on it system was also investigated. ► The non linear least-squares curve fitting program KINFIT was applied to study of CL

  8. Oxalate metabolism in liquid cultures of Ceriporiopsis subvermispora : a possible pathway for extracellular H2O2 production

    Science.gov (United States)

    Ulises. Urzua; Claudio. Aguilar; Philip J. Kersten; Rafael. Vicuna

    1998-01-01

    In this work, the source of extracellular hydrogen peroxide in cultures of Ceriporiopsis subvermispora was investigated. A thorough search for the presence in the growth medium of oxidases known to be produced by other fungi gave negative results. We therefore explored the prospect that H2O2 might arise from the oxidation of organic acids by MnP. Both oxalate and...

  9. Catalase activity is stimulated by H2O2 in rich culture medium and is required for H2O2 resistance and adaptation in yeast ☆

    OpenAIRE

    Martins, Dorival; English, Ann M.

    2014-01-01

    Catalases are efficient scavengers of H2O2 and protect cells against H2O2 stress. Examination of the H2O2 stimulon in Saccharomyces cerevisiae revealed that the cytosolic catalase T (Ctt1) protein level increases 15-fold on H2O2 challenge in synthetic complete media although previous work revealed that deletion of the CCT1 or CTA1 genes (encoding peroxisomal/mitochondrial catalase A) does not increase the H2O2 sensitivity of yeast challenged in phosphate buffer (pH 7.4). This we attributed to...

  10. SO4= uptake and catalase role in preconditioning after H2O2-induced oxidative stress in human erythrocytes.

    Science.gov (United States)

    Morabito, Rossana; Remigante, Alessia; Di Pietro, Maria Letizia; Giannetto, Antonino; La Spada, Giuseppina; Marino, Angela

    2017-02-01

    Preconditioning (PC) is an adaptive response to a mild and transient oxidative stress, shown for the first time in myocardial cells and not described in erythrocytes so far. The possible adaptation of human erythrocytes to hydrogen peroxide (H 2 O 2 )-induced oxidative stress has been here verified by monitoring one of band 3 protein functions, i.e., Cl - /HCO 3 - exchange, through rate constant for SO 4 = uptake measurement. With this aim, erythrocytes were exposed to a mild and transient oxidative stress (30 min to either 10 or 100 μM H 2 O 2 ), followed by a stronger oxidant condition (300- or, alternatively, 600-μM H 2 O 2 treatment). SO 4 = uptake was measured by a turbidimetric method, and the possible role of catalase (CAT, significantly contributing to the anti-oxidant system in erythrocytes) in PC response has been verified by measuring the rate of H 2 O 2 degradation. The preventive exposure of erythrocytes to 10 μM H 2 O 2 , and then to 300 μM H 2 O 2 , significantly ameliorated the rate constant for SO 4 = uptake with respect to 300 μM H 2 O 2 alone, showing thus an adaptive response to oxidative stress. Our results show that (i) SO 4 = uptake measurement is a suitable model to monitor the effects of a mild and transient oxidative stress in human erythrocytes, (ii) band 3 protein anion exchange capability is retained after 10 μM H 2 O 2 treatment, (iii) PC response induced by the 10 μM H 2 O 2 pretreatment is clearly detected, and (iv) PC response, elicited by low-concentrated H 2 O 2 , is mediated by CAT enzyme and does not involve band 3 protein tyrosine phosphorylation pathways. Erythrocyte adaptation to a short-term oxidative stress may serve as a basis for future studies about the impact of more prolonged oxidative events, often associated to aging, drug consumption, chronic alcoholism, hyperglycemia, or neurodegenerative diseases.

  11. Low levels of iron enhance UV/H2O2 efficiency at neutral pH.

    Science.gov (United States)

    Ulliman, Sydney L; McKay, Garrett; Rosario-Ortiz, Fernando L; Linden, Karl G

    2018-03-01

    While the presence of iron is generally not seen as favorable for UV-based treatment systems due to lamp fouling and decreased UV transmittance, we show that low levels of iron can lead to improvements in the abatement of chemicals in the UV-hydrogen peroxide advanced oxidation process. The oxidation potential of an iron-assisted UV/H 2 O 2 (UV 254  + H 2 O 2  + iron) process was evaluated at neutral pH using iron levels below USEPA secondary drinking water standards (UV/H 2 O 2 systems. The effects of iron species (Fe 2+ and Fe 3+ ), iron concentration (0-0.3 mg/L), H 2 O 2 concentration (0-10 mg/L) and background water matrix (low-carbon tap (LCT) and well water) on HO production and compound removal were examined. Iron-assisted UV/H 2 O 2 efficiency was most influenced by the target chemical and the water matrix. Added iron to UV/H 2 O 2 was shown to increase the steady-state HO concentration by approximately 25% in all well water scenarios. While CBZ removal was unchanged by iron addition, 0.3 mg/L iron improved NDMA removal rates in both LCT and well water matrices by 15.1% and 4.6% respectively. Furthermore, the combination of UV/Fe without H 2 O 2 was also shown to enhance NDMA removal when compared to UV photolysis alone indicating the presence of degradation pathways other than HO oxidation. Copyright © 2017 Elsevier Ltd. All rights reserved.

  12. Lactobacillus Species Identification, H2O2 Production, and Antibiotic Resistance and Correlation with Human Clinical Status

    Science.gov (United States)

    Felten, Annie; Barreau, Claude; Bizet, Chantal; Lagrange, Philippe Henri; Philippon, Alain

    1999-01-01

    Lactobacilli recovered from the blood, cerebrospinal fluid, respiratory tract, and gut of 20 hospitalized immunocompromised septic patients were analyzed. Biochemical carbohydrate fermentation and total soluble cell protein profiles were used to identify the species. Hydrogen peroxide production was measured. Susceptibility to 19 antibiotics was tested by a diffusion method, and the MICs of benzylpenicillin, amoxicillin, imipenem, erythromycin, vancomycin, gentamicin, and levofloxacin were determined. A small number of species produced H2O2, and antibiotic susceptibilities were species related. Eighteen (90%) of the isolates were L. rhamnosus, one was L. paracasei subsp. paracasei, and one was L. crispatus. L. rhamnosus, L. paracasei subsp. paracasei isolates, and the type strains were neither H2O2 producers nor vancomycin susceptible (MICs, ≥256 μg/ml). L. crispatus, as well as most of the type strains of lactobacilli which belong to the L. acidophilus group, was an H2O2 producer and vancomycin susceptible (MICs, <4 μg/ml). PMID:9986841

  13. The performance and decolourization kinetics of O3/H2O2 oxidation of reactive green 19 dye in wastewater

    Science.gov (United States)

    Sabri, S. N.; Abidin, C. Z. A.; Fahmi; Kow, S. H.; Razali, N. A.

    2018-03-01

    The degradations characteristic of azo dye Reactive Green 19 (RG19) was investigated using advanced oxidation process (AOPs). It was evaluated based on colour and chemical oxygen demand (COD) removal. The effect of operational parameters such as initial dye concentration, initial dosage of hydrogen peroxide (H2O2), contact time, and pH was also being studied. The samples were treated by ozonation (O3) and peroxone O3/H2O2 process. Advanced oxidation processes (AOPs) involve two stages of oxidation; firstly is the formation of strong oxidant and secondly the reaction of organic contaminants in water. In addition, the term advanced oxidation is referring to the processes in which oxidation of organic contaminants occurs primarily through reactions with hydroxyl radicals. There are several analyses that use to determine the efficiency of the treatment process, which are UV-Vis absorption spectra, COD, Fourier Transform Infrared (FT-IR), and pH. The results demonstrated that the ozone oxidation was efficient in decolourization and good in mineralization, based on the reduction of colour and COD. Additionally, results indicate that H2O2 is able to perform better than ozonation in order to decolourize the dye wastewater with 0.5 mL H2O2/L dye dosage of H2O2 at different initial concentration, initial pH, with contact time.

  14. Reactions of Ferrous Coproheme Decarboxylase (HemQ) with O2 and H2O2 Yield Ferric Heme b.

    Science.gov (United States)

    Streit, Bennett R; Celis, Arianna I; Shisler, Krista; Rodgers, Kenton R; Lukat-Rodgers, Gudrun S; DuBois, Jennifer L

    2017-01-10

    A recently discovered pathway for the biosynthesis of heme b ends in an unusual reaction catalyzed by coproheme decarboxylase (HemQ), where the Fe(II)-containing coproheme acts as both substrate and cofactor. Because both O 2 and H 2 O 2 are available as cellular oxidants, pathways for the reaction involving either can be proposed. Analysis of reaction kinetics and products showed that, under aerobic conditions, the ferrous coproheme-decarboxylase complex is rapidly and selectively oxidized by O 2 to the ferric state. The subsequent second-order reaction between the ferric complex and H 2 O 2 is slow, pH-dependent, and further decelerated by D 2 O 2 (average kinetic isotope effect of 2.2). The observation of rapid reactivity with peracetic acid suggested the possible involvement of Compound I (ferryl porphyrin cation radical), consistent with coproheme and harderoheme reduction potentials in the range of heme proteins that heterolytically cleave H 2 O 2 . Resonance Raman spectroscopy nonetheless indicated a remarkably weak Fe-His interaction; how the active site structure may support heterolytic H 2 O 2 cleavage is therefore unclear. From a cellular perspective, the use of H 2 O 2 as an oxidant in a catalase-positive organism is intriguing, as is the unusual generation of heme b in the Fe(III) rather than Fe(II) state as the end product of heme synthesis.

  15. A fast-response two-photon fluorescent probe for imaging endogenous H2O2 in living cells and tissues

    Science.gov (United States)

    Lu, Yanan; Shi, Xiaomin; Fan, Wenlong; Black, Cory A.; Lu, Zhengliang; Fan, Chunhua

    2018-02-01

    As a second messenger, hydrogen peroxide plays significant roles in numerous physiological and pathological processes and is related to various diseases including inflammatory disease, diabetes, neurodegenerative disorders, cardiovascular disease and Alzheimer's disease. Two-photon (TP) fluorescent probes reported for the detection of endogenous H2O2 are rare and most have drawbacks such as slow response and low sensitivity. In this report, we demonstrate a simple H2O2-specific TP fluorescent probe (TX-HP) containing a two-photon dye 6-hydroxy-2,3,4,4a-tetrahydro-1H-xanthen-1-one (TX) on the modulation of the ICT process. The probe exhibits a rapid fluorescent response to H2O2 in 9 min with both high sensitivity and selectivity. The probe can detect exogenous H2O2 in living cells. Furthermore, the probe is successfully utilized for imaging H2O2 in liver tissues.

  16. Activation of H2O2-induced VSOR Cl- currents in HTC cells require phospholipase Cgamma1 phosphorylation and Ca2+ mobilisation

    DEFF Research Database (Denmark)

    Varela, Diego; Simon, Felipe; Olivero, Pablo

    2007-01-01

    )R) blocker 2-APB. In line with these results, manoeuvres that prevented PLCgamma1 activation and/or [Ca(2+)](i) rise, abolished H(2)O(2)-induced VSOR Cl(-) currents. Furthermore, in cells that overexpress a phosphorylation-defective dominant mutant of PLCgamma1, H(2)O(2) did not induce activation......Volume-sensitive outwardly rectifying (VSOR) Cl(-) channels participate in several physiological processes such as regulatory volume decrease, cell cycle regulation, proliferation and apoptosis. Recent evidence points to a significant role of hydrogen peroxide (H(2)O(2)) in VSOR Cl(-) channel...... activation. The aim of this study was to determine the signalling pathways responsible for H(2)O(2)-induced VSOR Cl(-) channel activation. In rat hepatoma (HTC) cells, H(2)O(2) elicited a transient increase in tyrosine phosphorylation of phospholipase Cgamma1 (PLCgamma1) that was blocked by PP2, a Src...

  17. Pt-MWCNT modified carbon electrode strip for rapid and quantitative detection of H2O2 in food

    Directory of Open Access Journals (Sweden)

    Tai-Cheng Chou

    2018-04-01

    Full Text Available A single-use screen-printed carbon electrode strip was designed and fabricated. Nanohybrids, prepared by deposition of platinum (Pt nanoparticles on multi-wall carbon nanotube (MWCNT, was modified on the surface of screen-printed carbon electrode for the development of a fast, sensitive and cost-effective hydrogen peroxide (H2O2 detection amperometric sensor strip. With Pt-MWCNT nanohybrids surface modification, current generated in response to H2O2 by the screen-printed carbon electrode strip was enhanced 100 fold with an applied potential of 300 mV. Quality of as-prepared electrode strip was assured by the low coefficient of variation (CV (<5% of currents measured at 5 s. Three linear detection ranges with sensitivity of 75.2, 120.7, and 142.8 μA mM−1 cm−2 were observed for H2O2 concentration in the range of 1–15 mM, 0.1–1 mM, and 10–100 μM, respectively. The lowest H2O2 concentration could be measured by the as-prepared strip was 10 μM. H2O2 levels in green tea infusion and pressed Tofu could be rapidly detected with results comparable to that measured by ferrous oxidation xylenol orange (FOX assay and peroxidase colorimetric method. Keywords: Platinum-multi-wall carbon nanotube (Pt-MWCNT, Disposable carbon electrode, Hydrogen peroxide (H2O2, Amperometric sensor

  18. Regulation of Substantia Nigra Pars Reticulata GABAergic Neuron Activity by H2O2 via Flufenamic Acid-Sensitive Channels and KATP Channels

    Science.gov (United States)

    Lee, Christian R.; Witkovsky, Paul; Rice, Margaret E.

    2011-01-01

    Substantia nigra pars reticulata (SNr) GABAergic neurons are key output neurons of the basal ganglia. Given the role of these neurons in motor control, it is important to understand factors that regulate their firing rate and pattern. One potential regulator is hydrogen peroxide (H2O2), a reactive oxygen species that is increasingly recognized as a neuromodulator. We used whole-cell current clamp recordings of SNr GABAergic neurons in guinea-pig midbrain slices to determine how H2O2 affects the activity of these neurons and to explore the classes of ion channels underlying those effects. Elevation of H2O2 levels caused an increase in the spontaneous firing rate of SNr GABAergic neurons, whether by application of exogenous H2O2 or amplification of endogenous H2O2 through inhibition of glutathione peroxidase with mercaptosuccinate. This effect was reversed by flufenamic acid (FFA), implicating transient receptor potential (TRP) channels. Conversely, depletion of endogenous H2O2 by catalase, a peroxidase enzyme, decreased spontaneous firing rate and firing precision of SNr neurons, demonstrating tonic control of firing rate by H2O2. Elevation of H2O2 in the presence of FFA revealed an inhibition of tonic firing that was prevented by blockade of ATP-sensitive K+ (KATP) channels with glibenclamide. In contrast to guinea-pig SNr neurons, the dominant effect of H2O2 elevation in mouse SNr GABAergic neurons was hyperpolarization, indicating a species difference in H2O2-dependent regulation. Thus, H2O2 is an endogenous modulator of SNr GABAergic neurons, acting primarily through presumed TRP channels in guinea-pig SNr, with additional modulation via KATP channels to regulate SNr output. PMID:21503158

  19. MAPK inhibitors, particularly the JNK inhibitor, increase cell death effects in H2O2-treated lung cancer cells via increased superoxide anion and glutathione depletion.

    Science.gov (United States)

    Park, Woo Hyun

    2018-02-01

    Reactive oxygen species (ROS), especially hydrogen peroxide (H2O2), induce apoptosis in cancer cells by regulating mitogen-activated protein kinase (MAPK) signaling pathways. The present study investigated the effects of MAPK inhibitors on cell growth and death as well as changes in ROS and glutathione (GSH) levels in H2O2-treated Calu-6 and A549 lung cancer cells. H2O2 inhibited growth and induced death of Calu-6 and A549 lung cancer cells. All MAPK inhibitors appeared to enhance growth inhibition in H2O2-treated Calu-6 and A549 lung cancer cells and increased the percentage of Annexin V-FITC-positive cells in these cancer cells. Among the MAPK inhibitors, a JNK inhibitor significantly augmented the loss of mitochondrial membrane potential (MMP; ΔΨm) in H2O2-treated Calu-6 and A549 lung cancer cells. Intracellular ROS levels were significantly increased in the H2O2-treated cells at 1 and 24 h. Only the JNK inhibitor increased ROS levels in the H2O2-treated cells at 1 h and all MAPK inhibitors raised superoxide anion levels in these cells at 24 h. In addition, H2O2 induced GSH depletion in Calu-6 and A549 cells and the JNK inhibitor significantly enhanced GSH depletion in H2O2‑treated cells. Each of the MAPK inhibitors altered ROS and GSH levels differently in the Calu-6 and A549 control cells. In conclusion, H2O2 induced growth inhibition and death in lung cancer cells through oxidative stress and depletion of GSH. The enhanced effect of MAPK inhibitors, especially the JNK inhibitor, on cell death in H2O2-treated lung cancer cells was correlated with increased O2•- levels and GSH depletion.

  20. Role of H2O2 in the photo-transformation of phenol in artificial and natural seawater

    International Nuclear Information System (INIS)

    Calza, Paola; Campra, Laura; Pelizzetti, Ezio; Minero, Claudio

    2012-01-01

    In previous works, it was observed that phenol photo-induced transformation in natural seawater (NSW) mediated by natural photosensitizers occurs and leads to the formation of numerous hydroxylated, condensed, halogenated and nitroderivatives. Irradiation of NSW added with phenol and iron species had provided the enhanced formation of several halophenols, suggesting a central role played by iron species on the phenol halogenation in marine water. In this paper, we focus on hydrogen peroxide, another key photosensitizer, and its interaction with iron species. The ability of Fe(II)/Fe(III) and H 2 O 2 species to act as photo-sensitizers towards the transformation of organic compounds in seawater was investigated under simulated solar radiation. Light activation is necessary to induce the transformation of phenol, as no degradation occurs in the dark when either H 2 O 2 or iron/H 2 O 2 are initially added to artificial seawater (ASW). Fe(II) is easily transformed into Fe(III), assessing that a Fenton reaction (dark, Fe(II)/H 2 O 2 ) does not take place in marine environment, in favour of a photo-activated reaction involving Fe(III) and H 2 O 2 . When NSW is spiked with H 2 O 2 and Fe(III), halophenols' and nitrophenols' concentration decreases and completely disappears at high hydrogen peroxide concentration. Since Fe(II) and Fe(III) in spiked seawater induce an enhanced formation of haloderivatives, an excess of hydrogen peroxide act as scavenger towards the photo-produced chloro/bromo radicals, so hindering halogenation process in seawater. Hence, even if hydrogen peroxide efficiently induces the ·OH radical formation, and could then promote the phenol phototransformation, nevertheless it is negligibly involved in the production of the intermediates formed during phenol photolysis in seawater, whose formation is necessarily linked to other photosensitizer species. - Highlights: ► Hydrogen peroxide-mediated solar-driven transformations of pollutant in seawater are

  1. Fucoxanthin prevents H2O2-induced neuronal apoptosis via concurrently activating the PI3-K/Akt cascade and inhibiting the ERK pathway.

    Science.gov (United States)

    Yu, Jie; Lin, Jia-Jia; Yu, Rui; He, Shan; Wang, Qin-Wen; Cui, Wei; Zhang, Jin-Rong

    2017-01-01

    Background : As a natural carotenoid abundant in chloroplasts of edible brown algae, fucoxanthin possesses various health benefits, including anti-oxidative activity in particular. Objective : In the present study, we studied whether fucoxanthin protected against hydrogen peroxide (H 2 O 2 )-induced neuronal apoptosis. Design : The neuroprotective effects of fucoxanthin on H 2 O 2 -induced toxicity were studied in both SH-SY5Y cells and primary cerebellar granule neurons. Results : Fucoxanthin significantly protected against H 2 O 2 -induced neuronal apoptosis and intracellular reactive oxygen species. H 2 O 2 treatment led to the reduced activity of phosphoinositide 3-kinase (PI3-K)/Akt cascade and the increased activity of extracellular signal-regulated kinase (ERK) pathway in SH-SY5Y cells. Moreover, fucoxanthin significantly restored the altered activities of PI3-K/Akt and ERK pathways induced by H 2 O 2 . Both specific inhibitors of glycogen synthase kinase 3β (GSK3β) and mitogen-activated protein kinase kinase (MEK) significantly protected against H 2 O 2 -induced neuronal death. Furthermore, the neuroprotective effects of fucoxanthin against H 2 O 2 -induced neuronal death were abolished by specific PI3-K inhibitors. Conclusions : Our data strongly revealed that fucoxanthin protected against H 2 O 2 -induced neurotoxicity via concurrently activating the PI3-K/Akt cascade and inhibiting the ERK pathway, providing support for the use of fucoxanthin to treat neurodegenerative disorders induced by oxidative stress.

  2. In Situ Forming and H2O2-Releasing Hydrogels for Treatment of Drug-Resistant Bacterial Infections.

    Science.gov (United States)

    Lee, Yunki; Choi, Kyong-Hoon; Park, Kyung Min; Lee, Jong-Min; Park, Bong Joo; Park, Ki Dong

    2017-05-24

    Various types of commercialized wound dressings (e.g., films, foams, gels, and nanofiber meshes) have been clinically used as a physical barrier against bacterial invasion and as wound-healing materials. Although these dressings can protect the wounded tissue from the external environment, they cannot treat the wounds that are already infected with bacteria. Herein, we report in situ H 2 O 2 -releasing hydrogels as an active wound dressing with antibacterial properties for treatment of drug-resistant bacterial infection. In this study, H 2 O 2 was used for two major purposes: (1) in situ gel formation via a horseradish peroxidase (HRP)/H 2 O 2 -triggered cross-linking reaction, and (2) antibacterial activity of the hydrogel via its oxidative effects. We found that there were residual H 2 O 2 in the matrix after in situ HRP-catalyzed gelling, and varying the feed amount of H 2 O 2 (1-10 mM; used to make hydrogels) enabled control of H 2 O 2 release kinetics within a range of 2-509 μM. In addition, although the gelatin-hydroxyphenyl propionic acid (GH) gel called "GH 10" (showing the greatest H 2 O 2 release, 509 μM) slightly decreased cell viability (to 82-84%) of keratinocyte (HaCaT) and fibroblast (L-929) cells in in vitro assays, none of the hydrogels showed significant cytotoxicity toward tissues in in vivo skin irritation tests. When the H 2 O 2 -releasing hydrogels that promote in vivo wound healing, were applied to various bacterial strains in vitro and ex vivo, they showed strong killing efficiency toward Gram-positive bacteria including Staphylococcus aureus, S. epidermidis, and clinical isolate of methicillin-resistant S. aureus (MRSA, drug-resistant bacteria), where the antimicrobial effect was dependent on the concentration of the H 2 O 2 released. The present study suggests that our hydrogels have great potential as an injectable/sprayable antimicrobial dressing with biocompatibility and antibacterial activity against drug-resistant bacteria including

  3. Yield of H2O2 in Gas-Liquid Phase with Pulsed DBD

    Science.gov (United States)

    Jiang, Song; Wen, Yiyong; Liu, Kefu

    2014-01-01

    Electric discharge in water can generate a large number of oxidants such as ozone, hydrogen peroxide and hydroxyl radicals. In this paper, a non-thermal plasma processing system was established by means of pulsed dielectric barrier discharge in gas-liquid phase. The electrodes of discharge reactor were staggered. The yield of H2O2 was enhanced after discharge. The effects of discharge time, discharge voltage, frequency, initial pH value, and feed gas were investigated. The concentration of hydrogen peroxide and ozone was measured after discharge. The experimental results were fully analyzed. The chemical reaction equations in water were given as much as possible. At last, the water containing Rhodamine B was tested in this system. The degradation rate came to 94.22% in 30 min.

  4. Removing polysaccharides-and saccharides-related coloring impurities in alkyl polyglycosides by bleaching with the H2O2/TAED/NaHCO3 system.

    Science.gov (United States)

    Yanmei, Liu; Jinliang, Tao; Jiao, Sun; Wenyi, Chen

    2014-11-04

    The effect of H2O2/TAED/NaHCO3 system, namely NaHCO3 as alkaline agent with the (tetra acetyl ethylene diamine (TAED)) TAED-activated peroxide system, bleaching of alkyl polyglycosides solution was studied by spectrophotometry. The results showed that the optimal bleaching conditions about H2O2/TAED/NaHCO3 system bleaching of alkyl polyglycosides solution were as follows: molar ratio of TAED to H2O2 was 0.06, addition of H2O2 was 8.6%, addition of NaHCO3 was 3.2%, bleaching temperature of 50-65 °C, addition of MgO was 0.13%, and bleaching time was 8h. If too much amount of NaHCO3 was added to the system and maintained alkaline pH, the bleaching effect would be greatly reduced. Fixing molar ratio of TAED to H2O2 and increasing the amount of H2O2 were beneficial to improve the whiteness of alkyl polyglycosides, but adding too much amount of H2O2 would reduce the transparency. In the TAED-activated peroxide system, NaHCO3 as alkaline agent and buffer agent, could overcome the disadvantage of producing black precipitates when NaOH as alkaline agent. Copyright © 2014 Elsevier Ltd. All rights reserved.

  5. Induction of single-strand DNA breaks in human cells by H2O2 formed in near-uv (black light)-irradiated medium

    International Nuclear Information System (INIS)

    Wang, R.J.; Ananthaswamy, H.N.; Nixon, B.T.; Hartman, P.S.; Eisenstark, A.

    1980-01-01

    When Dulbecco's modified Eagle's medium (depleted of phenol red) was irradiated for up to 3 h by 4 to 5 W/m 2 black light, hydrogen peroxide (H 2 O 2 ) was produced. Generation of H 2 O 2 resulted from riboflavin-sensitized photooxidation of tryptophan and tyrosine. Reagent H 2 O 2 , or hydrogen peroxide generated in black light-exposed aqueous solutions containing riboflavin and tryptophan, induced 2 x 10 4 single-strand breaks per 10 16 daltons of DNA in intact, physiologically viable human D98/AH 2 cells. Concomitant with the single-strand breaks in the cells was loss of cellular reproductive viability. Two classes of photoproducts were identified: H 2 O 2 and non-H 2 O 2 . The H 2 O 2 component of the photoproducts was responsible for all the single-strand break induction but for only partial loss of reproductive viability. The non-H 2 O 2 photoproducts, accountable for the remainder of cell lethality, caused no single-strand breaks

  6. Metastable α-AgVO3 microrods as peroxidase mimetics for colorimetric determination of H2O2.

    Science.gov (United States)

    Wang, Yi; Zhang, Dun; Wang, Jin

    2017-12-01

    Single phase metastable α-AgVO 3 microrods with high crystallinity, tetragonal rod-like microstructure, uniform particle size distribution, and good dispersion were synthesized by direct coprecipitation at room temperature. They are shown to be viable peroxidase mimics that catalyze the oxidation of 3,3',5,5'-tetramethylbenzidine in the presence of H 2 O 2 . Kinetic analysis indicated typical Michaelis-Menten catalytic behavior. The findings were used to design a colorimetric assay for H 2 O 2 , best measured at 652 nm. The method has a linear response in the 60 to 200 μM H 2 O 2 concentration range, with a 2 μM detection limit. Benefitting from the chemical stability of the microrods, the method is well reproducible. It also is easily performed and highly specific. Graphic abstract Single phase metastable α-AgVO 3 microrods with high crystallinity, tetragonal rod-like microstructure, uniform particle size distribution, and good dispersion can efficiently catalyze the oxidation reaction of peroxidase substrate 3,3',5,5'-tetramethylbenzidine (TMB) in the presence of H 2 O 2 to produce a blue color change.

  7. Anchor of Ni2+ on the Agmatine Sulfate-Modified Electrodes for the Determination of H2O2 in Food

    Science.gov (United States)

    Yan, Yuhua; Zhang, Zhonghui; Xiao, Mingshu; Zhou, Hualan

    2017-07-01

    A method was developed to conveniently and rapidly determine hydrogen peroxide (H2O2) in food. The glassy carbon electrode (GCE) modified with agmatine sulfate (AS) easily anchoring nickel ion was attached to AS with polyamine structure. As a result, more Ni2+ was obtained and transformed to Ni(OH)2/NiOOH on the AS-GCE, which caused the electrode to own much better electrocatalytic performance on H2O2. Based on these, the content of H2O2 in thin sheet of bean curd sample was detected with standard addition method, by which good results were obtained.

  8. Density functional study on the heterogeneous oxidation of NO over α-Fe_2O_3 catalyst by H_2O_2: Effect of oxygen vacancy

    International Nuclear Information System (INIS)

    Song, Zijian; Wang, Ben; Yu, Jie; Ma, Chuan; Zhou, Changsong; Chen, Tao; Yan, Qianqian; Wang, Ke; Sun, Lushi

    2017-01-01

    Highlights: • NO and H_2O_2 adsorption on perfect and oxygen defect α-Fe_2O_3 (0 0 1) surface were studied by DFT calculations. • H_2O_2 shows high chemical reactivity for its adsorption on oxygen defect α-Fe_2O_3 (0 0 1) surface. • Oxygen vacancy plays an important role of the catalytic oxidation of NO by H_2O_2 over the α-Fe_2O_3 catalyst surfaces. • Mechanism of NO oxidation over α-Fe_2O_3 (0 0 1) surface by H_2O_2 was explained. - Abstract: Catalytic oxidation with H_2O_2 is a promising method for NOx emission control in coal-fired power plants. Hematite-based catalysts are attracting increased attention because of their surface redox reactivity. To elucidate the NO oxidation mechanism on α-Fe_2O_3 surfaces, density functional theory (DFT) calculations were conducted by investigating the adsorption characteristics of nitric oxide (NO) and hydrogen peroxide (H_2O_2) on perfect and oxygen defect α-Fe_2O_3 (0 0 1) surfaces. Results show that NO was molecularly adsorbed on two kinds of surfaces. H_2O_2 adsorption on perfect surface was also in a molecular form; however, H_2O_2 dissociation occurred on oxygen defect α-Fe_2O_3 (0 0 1) surface. The adsorption intensities of the two gas molecules in perfect α-Fe_2O_3 (0 0 1) surface followed the order NO > H_2O_2, and the opposite was true for the oxygen defect α-Fe_2O_3 (0 0 1). Oxygen vacancy remarkably enhanced the adsorption intensities of NO and H_2O_2 and promoted H_2O_2 decomposition on catalyst surface. As an oxidative product of NO, HNO_2 was synthesized when NO and H_2O_2 co-adsorbed on the oxygen defect α-Fe_2O_3 (0 0 1) surface. Analyses of Mulliken population, electron density difference, and partial density of states showed that H_2O_2 decomposition followed the Haber–Weiss mechanism. The trends of equilibrium constants suggested that NO adsorption on α-Fe_2O_3 (0 0 1) surface was more favorable at low than at high temperatures, whereas H_2O_2 adsorption was favorable between 375 and

  9. Using H2O2 as oxidant in leaching of uranium ores. The new research on the reaction of H2O2 with Fe2+

    International Nuclear Information System (INIS)

    Gao Xizhen

    1997-05-01

    The new research on the reaction of H 2 O 2 with Fe 2+ has been studied. Through determining the electric potential, pH and O 2 release during the mutual titration between H 2 O 2 solution and FeSO 4 solution, deduced the chemical equations of H 2 O 2 (without free hydroxyl) oxidizing FeSO 4 and Fe 2 (SO 4 ) 3 oxidizing H 2 O 2 . The research results show that acid is a catalytic agent for decomposing H 2 O 2 to be O 2 and H 2 O besides iron ions. The maximum oxidizing potential is up to about 640 mV. While using H 2 O 2 as an oxidant in uranium heap leaching and in-situ leaching, controlling electric potential can be regarded as a method for adjusting the feeding speed of H 2 O 2 to keep the electric potential below 500 mV, thus the H 2 O 2 decomposition can be reduced. (13 refs., 3 tabs., 1 fig.)

  10. Decolorization and Mineralization of Reactive Dyes, by the H2O2/UV Process With Electrochemically Produced H2O2

    NARCIS (Netherlands)

    Jeric, T.; Bisselink, R.J.M.; Tongeren, W. van; Marechal. A.M. Le

    2013-01-01

    Decolorization of Reactive Red 238, Reactive Orange 16, Reactive Black 5 and Reactive Blue 4 was studied in the UV/H2O2 process with H2O2 being produced electrochemically. The experimental results show that decolorization increased considerably when switching on the electrochemical production of

  11. Application of TAED/H2O2 system for low temperature bleaching of crude cellulose extracted from jute fiber

    Science.gov (United States)

    Wen, Zuoqiang; Zou, Linbo; Wang, Weiming

    2018-03-01

    Tetraacetylethylenediamine (TAED) activated hydrogen peroxide system had been applied for bleaching of crude cellulose extracted from jute fiber. Comparing with conventional hydrogen peroxide bleaching system, those results showed that bleaching temperature and time could be effectively reduced, and a preferable whiteness could be produced under faint alkaline condition. And the optimum conditions for activated bleaching system could be summarized as molar ratio of H2O2/TAED 1:0.7, pH 8, pure hydrogen peroxide 0.09 mol/L, temperature 70 °C and time 60min.

  12. H2O2 levels in rainwater collected in south Florida and the Bahama Islands

    Science.gov (United States)

    Zika, R.; Saltzman, E.; Chameides, W. L.; Davis, D. D.

    1982-01-01

    Measurements of H2O2 in rainwater collected in Miami, Florida, and the Bahama Islands area indicate the presence of H2O2 concentration levels ranging from 100,000 to 700,000 M. No systematic trends in H2O2 concentration were observed during an individual storm, in marked contrast to the behavior of other anions for example, NO3(-), SO4(-2), and Cl(-). The data suggest that a substantial fraction of the H2O2 found in precipitation is generated by aqueous-phase reactions within the cloudwater rather than via rainout and washout of gaseous H2O2.

  13. Development of a Xanthene-Based Red-Emissive Fluorescent Probe for Visualizing H2O2 in Living Cells, Tissues and Animals.

    Science.gov (United States)

    Zhang, Nan; Dong, Baoli; Kong, Xiuqi; Wang, Chao; Song, Wenhui; Lin, Weiying

    2018-04-25

    Hydrogen peroxide (H 2 O 2 ) plays important roles in the regulation of many biological processes, and the abnormal level of H 2 O 2 has close relation with the initiation and progression of many diseases. Herein, we describe a novel red-emissive fluorescence probe (RhoB) for the visualization of H 2 O 2 in living cells, tissues and animals. RhoB was constructed on the basis of a xanthene-based red-emissive dye, and displayed nearly no fluorescence. After the treatment with H 2 O 2 , RhoB can exhibit red fluorescence with the emission wavelength at 638 nm. RhoB exhibited highly sensitive and selective response to H 2 O 2 . Density functional theory (DFT) calculations were conducted to shed light on the optical properties of RhoB, and natural bond orbital (NBO) calculations demonstrate that the boron atom shows the highest positive electricity and further support the response mechanism. RhoB was successfully applied for imaging of exogenous and endogenous H 2 O 2 in living cells, and also can be utilized for visualizing H 2 O 2 in living tissues and animals.

  14. The roles of H2S and H2O2 in regulating AsA-GSH cycle in the leaves of wheat seedlings under drought stress.

    Science.gov (United States)

    Shan, Changjuan; Zhang, Shengli; Ou, Xingqi

    2018-01-25

    This paper investigated the roles of hydrogen sulfide (H 2 S) and hydrogen peroxide (H 2 O 2 ) and the possible relationship between them in regulating the AsA-GSH cycle in wheat leaves under drought stress (DS). Results showed that DS markedly increased the production of H 2 S and H 2 O 2 , the transcript levels and activities of ascorbate peroxidase (APX), glutathione reductase (GR), monodehydroascorbate reductase (MDHAR), and dehydroascorbate reductase (DHAR); malondialdehyde (MDA) content; and electrolyte leakage (EL). Meanwhile, DS markedly reduced plant height and biomass. Above increases induced by drought stress except MDA content and EL were all suppressed by pretreatments with H 2 S synthesis inhibitor aminooxyaceticacid (AOA) and H 2 O 2 synthesis inhibitor diphenylene iodonium (DPI). Besides, pretreatments with AOA and DPI further significantly increased MDA content and EL and significantly reduced plant height and biomass under DS. DPI reduced the production of H 2 O 2 and H 2 S induced by DS. AOA also reduced the production of H 2 S and H 2 O 2 induced by DS. Pretreatments with NaHS + AOA and H 2 O 2 + DPI reversed above effects of AOA and DPI. Our results suggested that H 2 S and H 2 O 2 all participated in the up-regulation of AsA-GSH cycle in wheat leaves by DS and possibly affected each other.

  15. Measurement of H2O2 within Living Drosophila during Aging Using a Ratiometric Mass Spectrometry Probe Targeted to the Mitochondrial Matrix

    Science.gov (United States)

    Cochemé, Helena M.; Quin, Caroline; McQuaker, Stephen J.; Cabreiro, Filipe; Logan, Angela; Prime, Tracy A.; Abakumova, Irina; Patel, Jigna V.; Fearnley, Ian M.; James, Andrew M.; Porteous, Carolyn M.; Smith, Robin A.J.; Saeed, Saima; Carré, Jane E.; Singer, Mervyn; Gems, David; Hartley, Richard C.; Partridge, Linda; Murphy, Michael P.

    2011-01-01

    Summary Hydrogen peroxide (H2O2) is central to mitochondrial oxidative damage and redox signaling, but its roles are poorly understood due to the difficulty of measuring mitochondrial H2O2 in vivo. Here we report a ratiometric mass spectrometry probe approach to assess mitochondrial matrix H2O2 levels in vivo. The probe, MitoB, comprises a triphenylphosphonium (TPP) cation driving its accumulation within mitochondria, conjugated to an arylboronic acid that reacts with H2O2 to form a phenol, MitoP. Quantifying the MitoP/MitoB ratio by liquid chromatography-tandem mass spectrometry enabled measurement of a weighted average of mitochondrial H2O2 that predominantly reports on thoracic muscle mitochondria within living flies. There was an increase in mitochondrial H2O2 with age in flies, which was not coordinately altered by interventions that modulated life span. Our findings provide approaches to investigate mitochondrial ROS in vivo and suggest that while an increase in overall mitochondrial H2O2 correlates with aging, it may not be causative. PMID:21356523

  16. Fabrication of porous silicon nanowires by MACE method in HF/H2O2/AgNO3 system at room temperature

    Science.gov (United States)

    2014-01-01

    In this paper, the moderately and lightly doped porous silicon nanowires (PSiNWs) were fabricated by the ‘one-pot procedure’ metal-assisted chemical etching (MACE) method in the HF/H2O2/AgNO3 system at room temperature. The effects of H2O2 concentration on the nanostructure of silicon nanowires (SiNWs) were investigated. The experimental results indicate that porous structure can be introduced by the addition of H2O2 and the pore structure could be controlled by adjusting the concentration of H2O2. The H2O2 species replaces Ag+ as the oxidant and the Ag nanoparticles work as catalyst during the etching. And the concentration of H2O2 influences the nucleation and motility of Ag particles, which leads to formation of different porous structure within the nanowires. A mechanism based on the lateral etching which is catalyzed by Ag particles under the motivation by H2O2 reduction is proposed to explain the PSiNWs formation. PMID:24910568

  17. Cathodic detection of H2O2 based on nanopyramidal gold surface with enhanced electron transfer of myoglobin.

    Science.gov (United States)

    Xia, Peipei; Liu, Haiqing; Tian, Yang

    2009-04-15

    Direct and reversible electron transfer of myoglobin (Mb), for the first time, is achieved at nanopyramidal gold surface, which was fabricated by one-step electrodeposition, with redox formal potential of 0.21+/-0.01 V (vs. Ag/AgCl) and an apparent heterogeneous electron-transfer rate constant (k(s)) of 1.6+/-0.2 s(-1). Electrochemical investigation indicates that Mb is stably confined on the nanopyramidal gold surface and maintains electrocatalytic activity toward hydrogen peroxide (H(2)O(2)). The facilitated electron transfer combined with the intrinsic catalytical activity of Mb substantially construct the third-generation biosensor for H(2)O(2). The positive redox potential of Mb at the nanostructured gold electrode gives a strong basis for determination of H(2)O(2) with high selectivity. Besides this advantage, the present biosensor also exhibits quick response time, broad linear range, and good sensitivity. The dynamic detection linear range is from 1 microM to 1.4 mM with a detection limit of 0.5 microM at 3sigma. The striking analytical performance of the present biosensor, as well as the biocompatibility of gold nanostructures provided a potential for continuous, on-line detection of H(2)O(2) in the biological system.

  18. Ionic strength dependence of the oxidation of SO2 by H2O2 in sodium chloride particles

    Science.gov (United States)

    Ali, H. M.; Iedema, M.; Yu, X.-Y.; Cowin, J. P.

    2014-06-01

    The reaction of sulfur dioxide and hydrogen peroxide in the presence of deliquesced (>75% RH) sodium chloride (brine) particles was studied by utilizing a cross flow mini-reactor. The reaction kinetics were followed by observing chloride depletion in particles by computer-controlled scanning electron microscope with energy dispersive X-ray analysis, namely CCSEM/EDX. The reactions take place in concentrated mixed salt brine aerosols, for which no complete kinetic equilibrium data previously existed. We measured the Henry's law solubility of H2O2 in brine solutions to close that gap. We also calculated the reaction rate as the particle transforms continuously from concentrated NaCl brine to, eventually, a mixed NaHSO4 plus H2SO4 brine solution. The reaction rate of the SO2 oxidation by H2O2 was found to be influenced by the change in ionic strength as the particle undergoes compositional transformation, following closely the dependence of the third order rate constant on ionic strength as predicted using established rate equations. This is the first study that has measured the ionic strength dependence of sulfate formation (in non-aqueous media) from oxidation of mixed salt brine aerosols in the presence of H2O2. It also gives the first report of the dependence of the Henry's law constant of H2O2 on ionic strength.

  19. Improving Methane Production through Co-Digestion of Canola Straw and Buffalo Dung by H2O2 Pretreatment

    Directory of Open Access Journals (Sweden)

    ALTAF ALAM NOONARI

    2017-01-01

    Full Text Available In this study an effect of acidic pre-treatment on the CS (Canola Straw and BD (Buffalo Dung by anaerobic co-digestion was investigated. H2O2 (Hydrogen Peroxide is a mainly accustomed reagent, used as a bleaching agent in the different industries such as paper and wood. In the present study, it was used as a pre-treatment chemical at varying concentrations in batch reactors. The co-digestion of CS and BD was carried out in SAMPTS (Semi-Automatic Methane Potential Test System at mesophilic (37±1oC conditions. The CS was pretreated in glass bottles with different concentrations of the H2O2 for seven days. The inoculum used in the present study was an effluent of the CSTR (Continuous Stirred Tank Reactor, which was treating BD at mesophilic conditions. The specific methane production from the codigestion of canola straw and BD, by the pre-treatment of H2O2 at concentrations of 0.5, 1.0, and 1.5% were 530.8, 544.5, and 510.3 NmL CH4 g/VS, respectively. The significant reduction in the volatile solids of CS was observed at the optimum pre-treatment of 1.0% H2O2.

  20. Differential regulation of TRPV1 channels by H2O2: implications for diabetic microvascular dysfunction

    Science.gov (United States)

    DelloStritto, Daniel J.; Connell, Patrick J.; Dick, Gregory M.; Fancher, Ibra S.; Klarich, Brittany; Fahmy, Joseph N.; Kang, Patrick T.; Chen, Yeong-Renn; Damron, Derek S.; Thodeti, Charles K.

    2016-01-01

    We demonstrated previously that TRPV1-dependent coupling of coronary blood flow (CBF) to metabolism is disrupted in diabetes. A critical amount of H2O2 contributes to CBF regulation; however, excessive H2O2 impairs responses. We sought to determine the extent to which differential regulation of TRPV1 by H2O2 modulates CBF and vascular reactivity in diabetes. We used contrast echocardiography to study TRPV1 knockout (V1KO), db/db diabetic, and wild type C57BKS/J (WT) mice. H2O2 dose-dependently increased CBF in WT mice, a response blocked by the TRPV1 antagonist SB366791. H2O2-induced vasodilation was significantly inhibited in db/db and V1KO mice. H2O2 caused robust SB366791-sensitive dilation in WT coronary microvessels; however, this response was attenuated in vessels from db/db and V1KO mice, suggesting H2O2-induced vasodilation occurs, in part, via TRPV1. Acute H2O2 exposure potentiated capsaicin-induced CBF responses and capsaicin-mediated vasodilation in WT mice, whereas prolonged luminal H2O2 exposure blunted capsaicin-induced vasodilation. Electrophysiology studies re-confirms acute H2O2 exposure activated TRPV1 in HEK293A and bovine aortic endothelial cells while establishing that H2O2 potentiate capsaicin-activated TRPV1 currents, whereas prolonged H2O2 exposure attenuated TRPV1 currents. Verification of H2O2-mediated activation of intrinsic TRPV1 specific currents were found in isolated mouse coronary endothelial cells from WT mice and decreased in endothelial cells from V1KO mice. These data suggest prolonged H2O2 exposure impairs TRPV1-dependent coronary vascular signaling. This may contribute to microvascular dysfunction and tissue perfusion deficits characteristic of diabetes. PMID:26907473

  1. Application of H2O2 and H2O2/Fe0 in removal of Acid Red 18 dye from aqueous solutions

    Directory of Open Access Journals (Sweden)

    Nazari Shahram

    2013-08-01

    Full Text Available Background & Aims of the Study: Organic dyes with a complex structure are often toxic, carcinogenic, mutagenic, non-biodegradation and stable in the environment and if released to the environment without treatment can endanger the environment and human health. The aim of this study was to evaluate the performance of H2O2 and H2O2/Fe0 Iron in removal of dye Acid Red 18 from aqueous solutions. Materials & Methods: This study was conducted at the laboratory scale. In this study, the removal efficiency of Acid Red 18 from a synthetic solution by H2O2 and H2O2/Fe0 was investigated. As well as Effect of solution pH, dye concentration, Concentration of Nanoscale Zero-Valent Iron, H2O2 and contact time in decolorization efficiency was investigated. Results: Results show that in pH=3, Contact time of 80 minutes, dye concentration of 50 mg/l and Concentration of Nanoscale Zero-Valent Iron of 2 g/l and H2O2 concentration equal to 200 mmol/l, the removal efficiency was about 98%. Conclusions: According to the results of experiments, H2O2/Fe0 has high efficiency in removal of Acid Red 18 from aqueous solution.

  2. Profiling of cytosolic and mitochondrial H2O2 production using the H2O2-sensitive protein HyPer in LPS-induced microglia cells.

    Science.gov (United States)

    Park, Junghyung; Lee, Seunghoon; Lee, Hyun-Shik; Lee, Sang-Rae; Lee, Dong-Seok

    2017-07-27

    Dysregulation of the production of pro-inflammatory mediators in microglia exacerbates the pathologic process of neurodegenerative disease. ROS actively affect microglia activation by regulating transcription factors that control the expression of pro-inflammatory genes. However, accurate information regarding the function of ROS in different subcellular organelles has not yet been established. Here, we analyzed the pattern of cytosolic and mitochondrial H 2 O 2 formation in LPS-activated BV-2 microglia using the H 2 O 2- sensitive protein HyPer targeted to specific subcellular compartments. Our results show that from an early time, cytosolic H 2 O 2 started increasing constantly, whereas mitochondrial H 2 O 2 rapidly increased later. In addition, we found that MAPK affected cytosolic H 2 O 2 , but not mitochondrial H 2 O 2 . Consequently, our study provides the basic information about subcellular H 2 O 2 generation in activated microglia, and a useful tool for investigating molecular targets that can modulate neuroinflammatory responses. Copyright © 2017 Elsevier B.V. All rights reserved.

  3. The reduction of I2 by H2O2 in aqueous solution

    International Nuclear Information System (INIS)

    Ball, J.M.; Hnatiw, J.B.

    1996-01-01

    The reduction of iodine by hydrogen peroxide is an important process which leads to a lower amount of molecular iodine in irradiated solutions of iodide as the pH is increased. There is quite a large amount of information on the reaction now but no consensus in the literature on the mechanisms for reaction and the generally accepted mechanism does not appear to be correct. A number of studies of the kinetics of the reaction in the pH range 2-7 have been carried out where the iodine reduction process exhibited a 1/[H + ] 2 dependence consistent with the proposed mechanism which were attributed primarily to the reaction of H 2 O 2 with IO - . Deviations were observed in the pH range 6-7 and were explained by incorporating the reaction of I 2 OH - with H 2 O 2 . In some other experiments it was suggested that the failure to maintain a 1/[H + ] 2 dependence at high pH was due to the iodine hydrolysis being rate determining. Data from an experimental program performed at AECL described in this paper confirms that the 1/[H + ] 2 dependence does not hold at high pH. These studies were carried out as a function of acid, iodide, peroxide and buffer concentration for three buffers, barbital, citrate and phosphate. This paper discuss two mechanisms which involve the formation of an HOOI intermediate in the rate determining step and which adequately describe the experimental data. (author) 4 figs., 2 tabs., 23 refs

  4. CYP epoxygenase-derived H2O2 is involved in the endothelium-derived hyperpolarization (EDH) and relaxation of intrarenal arteries.

    Science.gov (United States)

    Muñoz, Mercedes; López-Oliva, Maria Elvira; Pinilla, Estéfano; Martínez, María Pilar; Sánchez, Ana; Rodríguez, Claudia; García-Sacristán, Albino; Hernández, Medardo; Rivera, Luis; Prieto, Dolores

    2017-05-01

    Reactive oxygen species (ROS) like hydrogen peroxide (H 2 O 2 ) are involved in the in endothelium-derived hyperpolarization (EDH)-type relaxant responses of coronary and mesenteric arterioles. The role of ROS in kidney vascular function has mainly been investigated in the context of harmful ROS generation associated to kidney disease. The present study was sought to investigate whether H 2 O 2 is involved in the endothelium-dependent relaxations of intrarenal arteries as well the possible endothelial sources of ROS generation involved in these responses. Under conditions of cyclooxygenase (COX) and nitric oxide (NO) synthase inhibition, acetylcholine (ACh) induced relaxations and stimulated H 2 O 2 release that were reduced by catalase and by the glutathione peroxidase (GPx) mimetic ebselen in rat renal interlobar arteries, suggesting the involvement of H 2 O 2 in the endothelium-dependent responses. ACh relaxations were also blunted by the CYP2C inhibitor sulfaphenazole and by the NADPH oxidase inhibitor apocynin. Acetylcholine stimulated both superoxide (O 2 •- ) and H 2 O 2 production that were reduced by sulfaphenazole and apocynin. Expression of the antioxidant enzyme CuZnSOD and of the H 2 O 2 reducing enzymes catalase and GPx-1 was found in both intrarenal arteries and renal cortex. On the other hand, exogenous H 2 O 2 relaxed renal arteries by decreasing vascular smooth muscle (VSM) intracellular calcium concentration [Ca 2+ ] i and markedly enhanced endothelial K Ca currents in freshly isolated renal endothelial cells. CYP2C11 and CYP2C23 epoxygenases were highly expressed in interlobar renal arteries and renal cortex, respectively, and were co-localized with eNOS in renal endothelial cells. These results demonstrate that H 2 O 2 is involved in the EDH-type relaxant responses of renal arteries and that CYP 2C epoxygenases are physiologically relevant endothelial sources of vasodilator H 2 O 2 in the kidney. Copyright © 2017 Elsevier Inc. All rights

  5. Etching and anti-etching strategy for sensitive colorimetric sensing of H2O2 and biothiols based on silver/carbon nanomaterial.

    Science.gov (United States)

    Hou, Wenli; Liu, Xiaoying; Lu, Qiujun; Liu, Meiling; Zhang, Youyu; Yao, Shouzhuo

    2018-02-01

    In this paper, the colorimetric sensing of H 2 O 2 related molecules and biothiols based on etching and anti-etching strategy was firstly proposed. Ag/carbon nanocomposite (Ag/C NC) was served as the sensing nanoprobe, which was synthesized via carbon dots (C-dots) as the reductant and stabilizer. The characteristic surface plasmon resonance (SPR) absorbance of Ag nanoparticles (AgNPs) was sensitive to the amount of hydrogen peroxide (H 2 O 2 ). It exhibited strong optical responses to H 2 O 2 with the solution colour changing from yellow to nearly colourless, which is resulted from the etching of Ag by H 2 O 2 . The sensing platform was further extended to detect H 2 O 2 related molecules such as lactate in coupling with the specific catalysis oxidation of L-lactate by lactate oxidase (LOx) and formation of H 2 O 2 . It provides wide linear range for detecting H 2 O 2 in 0.1-80μM and 80-220μM with the detection limit as low as 0.03μM (S/N=3). In the presence of biothiols, the etching from the H 2 O 2 can be hampered. Other biothiols exhibit anti-etching effects well. The strategy works well in detecting of typical biothiols including cysteine (Cys), homocysteine (Hcy) and glutathione (GSH). Thus, a simple colorimetric strategy for sensitive detection of H 2 O 2 and biothiols is proposed. It is believed that the colorimetric sensor based on etching and anti-etching strategy can be applied in other systems in chemical and biosensing areas. Copyright © 2017 Elsevier B.V. All rights reserved.

  6. Pretreatment of MQA, a caffeoylquinic acid derivative compound, protects against H2O2-induced oxidative stress in SH-SY5Y cells.

    Science.gov (United States)

    Tian, Xing; Gao, Lingyue; An, Li; Jiang, Xiaowen; Bai, Junpeng; Huang, Jian; Meng, Weihong; Zhao, Qingchun

    2016-12-01

    Compound MQA (1,5-O-dicaffeoyl-3-O-[4-malic acid methyl ester]-quinic acid) is a natural caffeoylquinic acid derivative isolated from Arctium lappa L. roots. This study aims to explore the neuroprotective effects of MQA against hydrogen peroxide (H 2 O 2 )-induced oxidative stress in SH-SY5Y neuroblastoma cells. The SH-SY5Y cells were divided into four groups, including control, 20 μM MQA, 200 μM H2O2, 200 μM H2O2 + 20 μM MQA groups. The effects of MQA on H 2 O 2 -induced cell death were measured by MTT and LDH assays. Hoechst 33342 and Annexin V-PI double staining were used to observed H2O2-induced apoptosis. Also, the effects of MQA on antioxidant system and mitochondrial pathway were explored. Further, steady-state phosphorylation levels of ERK1/2, Akt and GSK-3β were examined by Western blot analysis. Pretreatment with MQA prevented cell death in SH-SY5Y cells exposed to 200 μM H2O2 for 3 h. Meanwhile, Hoechst 33342 and Annexin V-PI double staining showed that MQA attenuated H 2 O 2 -induced apoptosis. These changes are related to elevation in SOD activity, reduction in MDA production and ROS formation, and increases in mitochondrial membrane potential (MMP). In addition, the potential mechanisms of MQA against H 2 O 2 -induced apoptosis are associated with increases in the Bcl-2/Bax ratio, decreases in cytochrome c release, caspase-3 and caspase-9 expressions, phosphorylation of ERK1/2, and dephosphorylation of AKT and GSK-3β. These findings suggest that protective effects of MQA against H 2 O 2 -induced apoptosis might be associated with mitochondrial apoptosis, ERK1/2 and AKT/GSK-3β pathway.

  7. Fractionated breath condensate sampling: H2O2 concentrations of the alveolar fraction may be related to asthma control in children

    Directory of Open Access Journals (Sweden)

    Trischler Jordis

    2012-02-01

    Full Text Available Abstract Background Asthma is a chronic inflammatory disease of the airways but recent studies have shown that alveoli are also subject to pathophysiological changes. This study was undertaken to compare hydrogen peroxide (H2O2 concentrations in different parts of the lung using a new technique of fractioned breath condensate sampling. Methods In 52 children (9-17 years, 32 asthmatic patients, 20 controls measurements of exhaled nitric oxide (FENO, lung function, H2O2 in exhaled breath condensate (EBC and the asthma control test (ACT were performed. Exhaled breath condensate was collected in two different fractions, representing mainly either the airways or the alveoli. H2O2 was analysed in the airway and alveolar fractions and compared to clinical parameters. Results The exhaled H2O2 concentration was significantly higher in the airway fraction than in the alveolar fraction comparing each single pair (p = 0.003, 0.032 and 0.040 for the whole study group, the asthmatic group and the control group, respectively. Asthma control, measured by the asthma control test (ACT, correlated significantly with the H2O2 concentrations in the alveolar fraction (r = 0.606, p = 0.004 but not with those in the airway fraction in the group of children above 12 years. FENO values and lung function parameters did not correlate to the H2O2 concentrations of each fraction. Conclusion The new technique of fractionated H2O2 measurement may differentiate H2O2 concentrations in different parts of the lung in asthmatic and control children. H2O2 concentrations of the alveolar fraction may be related to the asthma control test in children.

  8. H2O2 plays an important role in the lifestyle of Colletotrichum gloeosporioides during interaction with cowpea [Vigna unguiculata (L.) Walp].

    Science.gov (United States)

    Eloy, Ygor R G; Vasconcelos, Ilka M; Barreto, Ana L H; Freire-Filho, Francisco R; Oliveira, Jose T A

    2015-08-01

    Plant-fungus interactions usually generate H(2)O(2) in the infected plant tissue. H(2)O(2) has a direct antimicrobial effect and is involved in the cross-linking of cell walls, signaling, induction of gene expression, hypersensitive cell death and induced systemic acquired resistance. This has raised the hypothesis that H(2)O(2) manipulation by pharmacological compounds could alter the lifestyle of Colletotrichum gloeosporioides during interaction with the BR-3-Tracuateua cowpea genotype. The primary leaves of cowpea were excised, infiltrated with salicylic acid (SA), glucose oxidase + glucose (GO/G), catalase (CAT) or diphenyliodonium chloride (DPI), followed by spore inoculation on the adaxial leaf surface. SA or GO/G-treated plantlets showed increased H(2)O(2) accumulation and lipid peroxidation. The fungus used a subcuticular, intramural necrotrophic strategy, and developed secondary hyphae associated with the quick spread and rapid killing of host cells. However, CAT or DPI-treated leaves exhibited decreased H(2)O(2) concentration and lipid peroxidation and the fungus developed intracellular hemibiotrophic infection with vesicles, in addition to primary and secondary hyphal formation. These results suggest that H(2)O(2) plays an important role in the cowpea (C. gloeosporioides) pathosystem given that it affected fungal lifestyle during interaction. Copyright © 2015 The British Mycological Society. Published by Elsevier Ltd. All rights reserved.

  9. Selective effects of H2O2 on cyanobacterial photosynthesis

    Czech Academy of Sciences Publication Activity Database

    Drábková, Michaela; Matthijs, H. C. P.; Admiraal, W.; Maršálek, Blahoslav

    2007-01-01

    Roč. 45, č. 3 (2007), s. 363-369 ISSN 0300-3604 Grant - others:-(XE) EVK2-CT-2002-57004 Institutional research plan: CEZ:AV0Z60050516 Keywords : hydrogen peroxide * cyanobacteria * photosynthesis Subject RIV: EF - Botanics Impact factor: 0.976, year: 2007

  10. Graphene blended with SnO2 and Pd-Pt nanocages for sensitive non-enzymatic electrochemical detection of H2O2 released from living cells.

    Science.gov (United States)

    Fu, Yamin; Huang, Di; Li, Congming; Zou, Lina; Ye, Baoxian

    2018-07-19

    This paper described a novel, facile and nonenzymatic electrochemical biosensor to detect hydrogen peroxide (H 2 O 2 ). The sensor was fabricated based on Pd-Pt nanocages and SnO 2 /graphene nanosheets modified electrode (PdPt NCs@SGN/GCE). The electrochemical behavior of PdPt NCs@SGN/GCE exhibited excellent catalytic activity toward H 2 O 2 with fast response, high selectivity, superior sensitivity, low detection limit of 0.3 μM and large linear range from 1 μM to 300 μM. Under these obvious advantages, the constructed biosensor provided to be reliable for determination of H 2 O 2 secreted from human cervical cancer cells (Hela cells). Hence, the proposed biosensor is a promising candidate for detection of H 2 O 2 in situ released from living cells in clinical diagnostics. Copyright © 2018 Elsevier B.V. All rights reserved.

  11. Effect of H2O2 on the corrosion behavior of 304L stainless steel

    International Nuclear Information System (INIS)

    Song, Taek Ho

    1994-02-01

    In connection with the safe storage of high level nuclear waste, effect of H 2 O 2 on the corrosion behavior of 304L stainless steel was examined. Open circuit potentials and polarization curves were measured with and without H 2 O 2 . The experimental results show that H 2 O 2 increased corrosion potential and decreased pitting potential. The passive range, therefore, decreased as H 2 O 2 concentration increased, indicating that pitting resistance was decreased by the existence of H 2 O 2 in the electrolyte. These effects of H 2 O 2 on corrosion of 304L stainless steel are considered to be similar to those of γ-irradiation. To compare the effects of H 2 O 2 with those of O 2 , cathodic and anodic polarization curves were made in three types of electrolyte such as aerated, deaerated, and stirred electrolyte. The experimental results show that the effects of H 2 O 2 on the corrosion behavior were very similar to those of O 2 such as increase of corrosion potential, decrease of pitting resistance, and increase of repassivation potential. Further, H 2 O 2 played much greater role in controlling cathodic reaction rate in neutral water environment. In acid and alkaline media, potential shifts by H 2 O 2 were restricted by the large current density of proton reduction and by the le Chatelier's principle respectively

  12. Over-expression of Trxo1 increases the viability of tobacco BY-2 cells under H2O2 treatment.

    Science.gov (United States)

    Ortiz-Espín, Ana; Locato, Vittoria; Camejo, Daymi; Schiermeyer, Andreas; De Gara, Laura; Sevilla, Francisca; Jiménez, Ana

    2015-09-01

    Reactive oxygen species (ROS), especially hydrogen peroxide, play a critical role in the regulation of plant development and in the induction of plant defence responses during stress adaptation, as well as in plant cell death. The antioxidant system is responsible for controlling ROS levels in these processes but redox homeostasis is also a key factor in plant cell metabolism under normal and stress situations. Thioredoxins (Trxs) are ubiquitous small proteins found in different cell compartments, including mitochondria and nuclei (Trxo1), and are involved in the regulation of target proteins through reduction of disulphide bonds, although their role under oxidative stress has been less well studied. This study describes over-expression of a Trxo1 for the first time, using a cell-culture model subjected to an oxidative treatment provoked by H2O2. Control and over-expressing PsTrxo1 tobacco (Nicotiana tabacum) BY-2 cells were treated with 35 mm H2O2 and the effects were analysed by studying the growth dynamics of the cultures together with oxidative stress parameters, as well as several components of the antioxidant systems involved in the metabolism of H2O2. Analysis of different hallmarks of programmed cell death was also carried out. Over-expression of PsTrxo1 caused significant differences in the response of TBY-2 cells to high concentrations of H2O2, namely higher and maintained viability in over-expressing cells, whilst the control line presented a severe decrease in viability and marked indications of oxidative stress, with generalized cell death after 3 d of treatment. In over-expressing cells, an increase in catalase activity, decreases in H2O2 and nitric oxide contents and maintenance of the glutathione redox state were observed. A decreased content of endogenous H2O2 may be responsible in part for the delayed cell death found in over-expressing cells, in which changes in oxidative parameters and antioxidants were less extended after the oxidative

  13. Hydrogen peroxide photocycling in the Gulf of Aqaba, Red Sea.

    Science.gov (United States)

    Shaked, Yeala; Harris, Raviv; Klein-Kedem, Nir

    2010-05-01

    The dynamics of hydrogen peroxide (H(2)O(2)) was investigated from December 2007 to October 2008 in the Gulf of Aqaba, which in the absence of H(2)O(2) contribution from biological production, rain and runoff, turned out to be a unique natural photochemical laboratory. A distinct seasonal pattern emerged, with highest midday surface H(2)O(2) concentrations in spring-summer (30-90 nM) as compared to winter (10-30 nM). Similarly, irradiation normalized net H(2)O(2) formation rates obtained in concurrent ship-board experiments were faster in spring-summer than in winter. These seasonal patterns were attributed to changes in water characteristics, namely elevated spring-summer chromophoric dissolved organic matter (CDOM). The role of trace elements in H(2)O(2) photoformation was studied by simultaneously measuring superoxide (O(2)(-)), Fe(II), and H(2)O(2) formation and loss in ambient seawater and in the presence of superoxide dismutase, iron and copper. O(2)(-) was found to decay fast in the Gulf water, with a half-life of 15-28 s, primarily due to catalytic reactions with trace metals (predominantly copper). Hence, H(2)O(2) formation in the Gulf involves metal-catalyzed O(2)(-) disproptionation. Added iron moderately lowered net H(2)O(2) photoformation, probably due to its participation in Fe(II) oxidation, a process that may also modify H(2)O(2) formation in situ.

  14. A clinical evaluation comparing two H2O2 concentrations used with a light-assisted chairside tooth whitening system.

    Science.gov (United States)

    Ward, Marilyn; Felix, Heather

    2012-04-01

    The purpose of this study was to assess the efficacy of two different BriteSmile hydrogen peroxide (H2O2) gels in a split-arch protocol for whitening teeth in a clinical setting when used in conjunction with a BriteSmile BS4000 lamp. Fifteen subjects were enrolled into a single-center clinical trial. The efficacy of the BriteSmile BS4000 lamp using both 15% H2O2 and 25% H2O2 gel formulations was tested. Study subjects were concurrently exposed to the whitening lamp with the 15% H2O2 gel placed on half of their anterior teeth and the 25% H2O2 gel on the other half for a total light and gel exposure of 60 minutes. The clinical data collected were shade score, gingival health, and dentinal hypersensitivity self-assessment. Changes in tooth shade were better for subjects exposed to the 25% gel and the dental whitening lamp (average 8.0 shade changes) compared to subjects exposed to the 15% gel and dental whitening lamp (average 7.6 shade changes) immediately after treatment. The same held true at the 7-day follow-up (25% gel average 7.4 shade changes versus 15% gel average 7.3 shade changes). However, these differences were not statistically significant. No reports of irritation of gingival soft tissues were documented. The relative changes in mean sensitivity scores were similar for both groups with no significant differences in mean sensitivity scores between the groups. Both concentrations of H2O2 gel and the whitening lamp combined gave study subjects an average of 8.0 (25% gel) and 7.6 (15% gel) shade changes immediately after treatment. The 7-day follow-up examination resulted in a regression of lightest to an average of 7.4 (25% gel) and 7.3 (15% gel). It was concluded that the use of the chairside whitening light and either 15% or 25% hydrogen peroxide gel is safe and effective for whitening teeth in 1 hour.

  15. Mesospheric H2O and H2O2 densities inferred from in situ positive ion composition measurement

    Science.gov (United States)

    Kopp, E.

    1984-01-01

    A model for production and loss of oxonium ions in the high-latitude D-region is developed, based on the observed excess of 34(+) which has been interpreted as H2O2(+). The loss mechanism suggested in the study is the attachment of N2 and/or CO2 in three-body reactions. Furthermore, mesospheric water vapor and H2O2 densities are inferred from measurements of four high-latitude ion compositions, based on the oxonium model. Mixing ratios of hydrogen peroxide of up to two orders of magnitude higher than previous values were obtained. A number of reactions, reaction constants, and a block diagram of the oxonium ion chemistry in the D-region are given.

  16. Radiation-induced decomposition and decoloration of reactive dyes in the presence of H2O2

    International Nuclear Information System (INIS)

    Wang Min; Yang Ruiyuan; Wang Wenfeng; Shen Zhongqun; Bian Shaowei; Zhu Zhiyuan

    2006-01-01

    The dyeing wastewaters represent a large input of hazardous compounds to the environment and these compounds are usually non-biodegradable. In this study, electron beam irradiation-induced decoloration and decomposition of reactive dyes in aqueous solution were investigated. Two different reactive dyes (reactive red KE-3B and reactive blue XBR) solutions were irradiated with electron beam at different doses in the absence and presence of H 2 O 2 . The changes of absorption spectra and pH value were described and analyzed as well as the degree of decoloration and COD removal. The influences of absorbed doses, H 2 O 2 additions and initial dye concentrations are discussed. The experimental results show that reactive dyes in aqueous solutions can be effectively degraded by electron beam irradiation, especially in the presence of hydrogen peroxide

  17. Absolute linestrengths in the H2O2 nu6 band

    Science.gov (United States)

    May, Randy D.

    1991-01-01

    Absolute linestrengths at 295 K have been measured for selected lines in the nu6 band of H2O2 using a tunable diode-laser spectrometer. H2O2 concentrations in a flowing gas mixture were determined by ultraviolet (uv) absorption at 254 nm using a collinear infrared (ir) and uv optical arrangement. The measured linestrengths are approx. 60 percent larger than previously reported values when absorption by hot bands in H2O2 is taken into account.

  18. Effect of H2O2 on the corrosion behavior of 304L stainless steel

    International Nuclear Information System (INIS)

    Song, Taek Hoh; Kim, In Sub; Noh, Sung Kee

    1995-01-01

    In connection with the safe storage of high level nuclear waste, effect of H 2 O 2 on the corrosion behavior of 304L stainless steel was examined. Open circuit potentials and polarization curves were measured with and without H 2 O 2 . The experimental results show that H 2 O 2 increased corrosion potential and decreased pitting potential. The passive range, therefore, decreased as H 2 O 2 concentration increased, indicating that pitting resistance was decreased by the existence of H 2 O 2 in the electrolyte. These effects of H 2 O 2 on corrosion of 304L stainless steel are considered to be similar to those of γ-irradiation. To compare the effects of H 2 O 2 with those of O 2 , cathodic and anodic polarization curves were made in three types of electrolyte such as aerated, deaerated, and stirred electrolyte. The experimental results show that the effects of H 2 O 2 on the corrosion behavior were very similar to those of O 2 such as increase of corrosion potential, decrease of pitting resistance, and increase of repassivation potential. In acid and alkaline media, the corrosion potential shifts by H 2 O 2 were restricted by the large current density of proton reduction and by the le Chatelier's principle respectively. 13 figs., 1 tabs., 17 refs. (Author)

  19. Kinetic Studies on Enzyme-Catalyzed Reactions: Oxidation of Glucose, Decomposition of Hydrogen Peroxide and Their Combination

    Science.gov (United States)

    Tao, Zhimin; Raffel, Ryan A.; Souid, Abdul-Kader; Goodisman, Jerry

    2009-01-01

    The kinetics of the glucose oxidase-catalyzed reaction of glucose with O2, which produces gluconic acid and hydrogen peroxide, and the catalase-assisted breakdown of hydrogen peroxide to generate oxygen, have been measured via the rate of O2 depletion or production. The O2 concentrations in air-saturated phosphate-buffered salt solutions were monitored by measuring the decay of phosphorescence from a Pd phosphor in solution; the decay rate was obtained by fitting the tail of the phosphorescence intensity profile to an exponential. For glucose oxidation in the presence of glucose oxidase, the rate constant determined for the rate-limiting step was k = (3.0 ± 0.7) ×104 M−1s−1 at 37°C. For catalase-catalyzed H2O2 breakdown, the reaction order in [H2O2] was somewhat greater than unity at 37°C and well above unity at 25°C, suggesting different temperature dependences of the rate constants for various steps in the reaction. The two reactions were combined in a single experiment: addition of glucose oxidase to glucose-rich cell-free media caused a rapid drop in [O2], and subsequent addition of catalase caused [O2] to rise and then decrease to zero. The best fit of [O2] to a kinetic model is obtained with the rate constants for glucose oxidation and peroxide decomposition equal to 0.116 s−1 and 0.090 s−1 respectively. Cellular respiration in the presence of glucose was found to be three times as rapid as that in glucose-deprived cells. Added NaCN inhibited O2 consumption completely, confirming that oxidation occurred in the cellular mitochondrial respiratory chain. PMID:19348778

  20. Indirubin-3-Oxime Prevents H2O2-Induced Neuronal Apoptosis via Concurrently Inhibiting GSK3β and the ERK Pathway.

    Science.gov (United States)

    Yu, Jie; Zheng, Jiacheng; Lin, Jiajia; Jin, Linlu; Yu, Rui; Mak, Shinghung; Hu, Shengquan; Sun, Hongya; Wu, Xiang; Zhang, Zaijun; Lee, Mingyuen; Tsim, Wahkeung; Su, Wei; Zhou, Wenhua; Cui, Wei; Han, Yifan; Wang, Qinwen

    2017-05-01

    Oxidative stress-induced neuronal apoptosis plays an important role in many neurodegenerative disorders. In this study, we have shown that indirubin-3-oxime, a derivative of indirubin originally designed for leukemia therapy, could prevent hydrogen peroxide (H 2 O 2 )-induced apoptosis in both SH-SY5Y cells and primary cerebellar granule neurons. H 2 O 2 exposure led to the increased activities of glycogen synthase kinase 3β (GSK3β) and extracellular signal-regulated kinase (ERK) in SH-SY5Y cells. Indirubin-3-oxime treatment significantly reversed the altered activity of both the PI3-K/Akt/GSK3β cascade and the ERK pathway induced by H 2 O 2 . In addition, both GSK3β and mitogen-activated protein kinase inhibitors significantly prevented H 2 O 2 -induced neuronal apoptosis. Moreover, specific inhibitors of the phosphoinositide 3-kinase (PI3-K) abolished the neuroprotective effects of indirubin-3-oxime against H 2 O 2 -induced neuronal apoptosis. These results strongly suggest that indirubin-3-oxime prevents H 2 O 2 -induced apoptosis via concurrent inhibiting GSK3β and the ERK pathway in SH-SY5Y cells, providing support for the use of indirubin-3-oxime to treat neurodegenerative disorders caused or exacerbated by oxidative stress.

  1. Induction of lipid peroxidation in erythrocytes during cholesterol oxidation catalyzed by cholesterol oxidase

    International Nuclear Information System (INIS)

    Kagan, V.E.; Monovich, O.; Ribarov, S.R.

    1986-01-01

    The authors study the ability of cholesterol oxidase (ChO), which catalyzes oxidation of cholesterol (Ch) to cholest-4-en-3-one and, at the same time, reduction of O 2 to H 2 O 2 , to induce the lipid peroxidation (LPO) in plasma membranes. Erythrocyte ghosts were obtained from guinea pig blood; the reaction of oxidation of Ch in the erythrocyte ghosts or in micelles with Triton X-100 was carried out in the following medium: Tris-HCl 0.2 M, pH 7.0 (at 37 C), Triton X-100 0.25%, and ChO 0.05 U/ml. At the present time ChO is often used to study the asymmetry of distribution of Ch in biomembranes and the velocity of its transbilayer migration. It is suggested that changes in membrane permeability do not take place during the reaction catalyzed by the enzyme, and no products capable of affecting flip-flop in biological are formed. Accumulation of LPO products in erythrocyte membranes discovered in this investigation under the influence of ChO compels critical re-examination of the resutls

  2. Protective Effects of an Ancient Chinese Kidney-Tonifying Formula against H2O2-Induced Oxidative Damage to MES23.5 Cells.

    Science.gov (United States)

    Xu, Yihui; Lin, Wei; Ye, Shuifen; Wang, Huajin; Wang, Tingting; Su, Youyan; Wu, Liangning; Wang, Yuanwang; Xu, Qian; Xu, Chuanshan; Cai, Jing

    2017-01-01

    Oxidative damage plays a critical role in the etiology of neurodegenerative disorders including Parkinson's disease (PD). In our study, an ancient Chinese kidney-tonifying formula, which consists of Cistanche , Epimedii, and Polygonatum cirrhifolium , was investigated to protect MES23.5 dopaminergic neurons against hydrogen peroxide- (H 2 O 2 -) induced oxidative damage. The damage effects of H 2 O 2 on MES23.5 cells and the protective effects of KTF against oxidative stress were evaluated using MTT assay, transmission electron microscopy (TEM), immunocytochemistry (ICC), enzyme-linked immunosorbent assay (ELISA), and immunoblotting. The results showed that cell viability was dramatically decreased after a 12 h exposure to 150  μ M H 2 O 2 . TEM observation found that the H 2 O 2 -treated MES23.5 cells presented cellular organelle damage. However, when cells were incubated with KTF (3.125, 6.25, and 12.5  μ g/ml) for 24 h after H 2 O 2 exposure, a significant protective effect against H 2 O 2 -induced damage was observed in MES23.5 cells. Using ICC, we found that KTF inhibited the reduction of the tyrosine hydroxylase (TH) induced by H 2 O 2 , upregulated the mRNA and protein expression of HO-1, CAT, and GPx-1, and downregulated the expression of caspase 3. These results indicated that KTF may provide neuron protection against H 2 O 2 -induced cell damage through ameliorating oxidative stress, and our findings provide a new potential strategy for the prevention and treatment of Parkinson's disease.

  3. Electrochemical Quantification of Extracellular Local H2O2 Kinetics Originating from Single Cells.

    Science.gov (United States)

    Bozem, Monika; Knapp, Phillip; Mirčeski, Valentin; Slowik, Ewa J; Bogeski, Ivan; Kappl, Reinhard; Heinemann, Christian; Hoth, Markus

    2017-05-15

    H 2 O 2 is produced by all eukaryotic cells under physiological and pathological conditions. Due to its enormous relevance for cell signaling at low concentrations and antipathogenic function at high concentrations, precise quantification of extracellular local H 2 O 2 concentrations ([H 2 O 2 ]) originating from single cells is required. Using a scanning electrochemical microscope and bare platinum disk ultramicroelectrodes, we established sensitive long-term measurements of extracellular [H 2 O 2 ] kinetics originating from single primary human monocytes (MCs) ex vivo. For the electrochemical techniques square wave voltammetry, cyclic and linear scan voltammetry, and chronoamperometry, detection limits for [H 2 O 2 ] were determined to be 5, 50, and 500 nM, respectively. Following phorbol ester stimulation, local [H 2 O 2 ] 5-8 μm above a single MC increased by 3.4 nM/s within the first 10 min before reaching a plateau. After extracellular addition of H 2 O 2 to an unstimulated MC, the local [H 2 O 2 ] decreased on average by 4.2 nM/s due to degradation processes of the cell. Using the scanning mode of the setup, we found that H 2 O 2 is evenly distributed around the producing cell and can still be detected up to 30 μm away from the cell. The electrochemical single-cell measurements were validated in MC populations using electron spin resonance spectroscopy and the Amplex ® UltraRed assay. Innovation and Conclusion: We demonstrate a highly sensitive, spatially, and temporally resolved electrochemical approach to monitor dynamics of production and degradation processes for H 2 O 2 separately. Local extracellular [H 2 O 2 ] kinetics originating from single cells is quantified in real time. Antioxid. Redox Signal. 00, 000-000.

  4. Optimization of NO oxidation by H2O2 thermal decomposition at moderate temperatures.

    Science.gov (United States)

    Zhao, Hai-Qian; Wang, Zhong-Hua; Gao, Xing-Cun; Liu, Cheng-Hao; Qi, Han-Bing

    2018-01-01

    H2O2 was adopted to oxidize NO in simulated flue gas at 100-500°C. The effects of the H2O2 evaporation conditions, gas temperature, initial NO concentration, H2O2 concentration, and H2O2:NO molar ratio on the oxidation efficiency of NO were investigated. The reason for the narrow NO oxidation temperature range near 500°C was determined. The NO oxidation products were analyzed. The removal of NOx using NaOH solution at a moderate oxidation ratio was studied. It was proven that rapid evaporation of the H2O2 solution was critical to increase the NO oxidation efficiency and broaden the oxidation temperature range. the NO oxidation efficiency was above 50% at 300-500°C by contacting the outlet of the syringe needle and the stainless-steel gas pipe together to spread H2O2 solution into a thin film on the surface of the stainless-steel gas pipe, which greatly accelerated the evaporation of H2O2. The NO oxidation efficiency and the NO oxidation rate increased with increasing initial NO concentration. This method was more effective for the oxidation of NO at high concentrations. H2O2 solution with a concentration higher than 15% was more efficient in oxidizing NO. High temperatures decreased the influence of the H2O2 concentration on the NO oxidation efficiency. The oxidation efficiency of NO increased with an increase in the H2O2:NO molar ratio, but the ratio of H2O2 to oxidized NO decreased. Over 80% of the NO oxidation product was NO2, which indicated that the oxidation ratio of NO did not need to be very high. An 86.7% NO removal efficiency was obtained at an oxidation ratio of only 53.8% when combined with alkali absorption.

  5. UV and VUV photolysis vs. UV/H2O2 and VUV/H2O2, treatment for removal of clofibric acid from aqueous solution.

    Science.gov (United States)

    Li, Wenzhen; Lu, Shuguang; Qiu, Zhaofu; Lin, Kuangfei

    2011-07-01

    Clofibric acid (CA), a metabolite of lipid regulators, was investigated in ultra-pure water and sewage treatment plant (STP) effluent at 10 degrees C under UV, vacuum UV (VUV), UV/H2O2 and VUV/H2O2 processes. The influences of NO3-, HCO3- and humic acid (HA) on CA photolysis in all processes were examined. The results showed that all the experimental data well fitted the pseudo-first-order kinetic model, and the apparent rate constant (k(ap)) and half-life time (t(1/2)) were calculated accordingly. Direct photolysis of CA through UV irradiation was the main process, compared with the indirect oxidation of CA due to the slight generation of hydroxyl radicals dissociated from water molecules under UV irradiation below 200 nm monochromatic wavelength emission. In contrast, indirect oxidation was the main CA degradation mechanism in UV/H2O2 and VUV/H2O2, and VUV/H2O2 was the most effective process for CA degradation. The addition of 20 mg L(-1) HA could significantly inhibit CA degradation, whereas, except for UV irradiation, the inhibitive effects of NO3- and HCO3- (1.0 x 10(-3) and 0.1 mol L(-1), respectively) on CA degradation were observed in all processes, and their adverse effects were more significant in UV/H2O2 and VUV/H2O2 processes, particularly at the high NO3- and HCO3- concentrations. The degradation rate decreased 1.8-4.9-fold when these processes were applied to a real STP effluent owing to the presence of complex constituents. Of the four processes, VUV/H2O2 was the most effective, and the CA removal efficiency reached over 99% after 40 min in contrast to 80 min in both the UV/H2O2 and VUV processes and 240 min in the UV process.

  6. Characterization and optimization of cathodic conditions for H2O2 synthesis in microbial electrochemical cells.

    Science.gov (United States)

    Sim, Junyoung; An, Junyeong; Elbeshbishy, Elsayed; Ryu, Hodon; Lee, Hyung-Sool

    2015-11-01

    Cathode potential and O2 supply methods were investigated to improve H2O2 synthesis in an electrochemical cell, and optimal cathode conditions were applied for microbial electrochemical cells (MECs). Using aqueous O2 for the cathode significantly improved current density, but H2O2 conversion efficiency was negligible at 0.3-12%. Current density decreased for passive O2 diffusion to the cathode, but H2O2 conversion efficiency increased by 65%. An MEC equipped with a gas diffusion cathode was operated with acetate medium and domestic wastewater, which presented relatively high H2O2 conversion efficiency from 36% to 47%, although cathode overpotential was fluctuated. Due to different current densities, the maximum H2O2 production rate was 141 mg H2O2/L-h in the MEC fed with acetate medium, but it became low at 6 mg H2O2/L-h in the MEC fed with the wastewater. Our study clearly indicates that improving anodic current density and mitigating membrane fouling would be key parameters for large-scale H2O2-MECs. Copyright © 2015 Elsevier Ltd. All rights reserved.

  7. Activity and Selectivity for O-2 Reduction to H2O2 on Transition Metal Surfaces

    DEFF Research Database (Denmark)

    Siahrostami, Samira; Verdaguer Casadevall, Arnau; Karamad, Mohammadreza

    2013-01-01

    Industrially viable electrochemical production of H2O2 requires active, selective and stable electrocatalyst materials to catalyse the oxygen reduction reaction to H2O2. On the basis of density functional theory calculations, we explain why single site catalysts such as Pd/Au show improved...

  8. System and method to control h2o2 level in advanced oxidation processes

    DEFF Research Database (Denmark)

    2016-01-01

    The present invention relates to a bio-electrochemical system (BES) and a method of in-situ production and removal of H2O2 using such a bio-electrochemical system (BES). Further, the invention relates to a method for in-situ control of H2O2 content in an aqueous system of advanced oxidation...

  9. Decolorization of Reactive Blue 19 Dye from Textile Wastewater by the UV/H2O2 Process

    Science.gov (United States)

    Rezaee, Abbas; Taghi Ghaneian, Mohammad; Jamalodin Hashemian, Sayed; Moussavi, Gholamreza; Khavanin, Ali; Ghanizadeh, Ghader

    Photo-oxidation of dyes is a new concern among researchers since it offers an attractive method for decoloration of dyes and breaks them into simple mineral forms. An advanced oxidation process, UV/H2O2, was investigated in a laboratory scale photoreactor for decolorization of the Reactive blue 19 (RB19) dye from synthetic textile wastewater. The effects of operating parameters such as hydrogen peroxide dosage, pH, initial dye concentration and UV dosage, on decolorization have been evaluated. The RB19 solution was completely decolorized under optimal hydrogen peroxide dosage of 2.5 mmol L-1 and low-pressure mercury UV-C lamps (55 w) in less than 30 min. The decolorization rate followed pseudo-first order kinetics with respect to the dye concentration. The rate increased linearly with volumetric UV dosage and nonlinearly with increasing initial hydrogen peroxide concentration. It has been found that the degradation rate increased until an optimum of hydrogen peroxide dosage, beyond which the reagent exerted an inhibitory effect. From the experimental results, the UV/H2O2 process was an effective technology for RB19 dye treatment in wastewater.

  10. Influence of concentration of H2O2 on the phase stability of TiO2-anatase

    International Nuclear Information System (INIS)

    Montanhera, M.A.; Pereira, E.A.; Paula, F.R.; Spada, E.R.; Faria, R.M.

    2014-01-01

    Titanium dioxide (TiO 2 ) is a semiconductor what has attracted increasing attention because of its physical and chemical properties. In this work, we report the preparation of TiO 2 nanoparticles by dissolving of titanium oxysulfate (TiOSO 4 ) in aqueous solution containing hydrogen peroxide (H 2 O 2 ) and subsequent thermal treatment of the precipitated complex. The results of X-ray diffractometry showed that the first stage of heat treatment at 600°C generates the anatase phase at all concentrations of H 2 O 2 investigated. On the other hand, when treated at 825 deg C, prepared samples with lower concentrations of H 2 O 2 (0.009 and 0.017 mol/L) showed only the rutile phase and for concentrations starting from 0.088 mol/L, is obtained only anatase phase. When the heat treatment is performed at 900°C, phase-pure anatase is obtained only for concentrations higher than 0.122 mol/L. The stability of the phase anatase is related to the crystallite size obtained of the first stage of heat treatment. When the heat treatment is performed at 900°C, phase-pure anatase is obtained only at higher concentrations than 0.122 mol/L. The stability of the phase anatase is related to the crystallite sizes obtained in the first step of heat treatment. (author)

  11. A novel H2S/H2O2 fuel cell operating at the room temperature

    Energy Technology Data Exchange (ETDEWEB)

    Sanli, Ayse Elif [Gazi University (Turkey)], email: aecsanli@gmail.com; Aytac, Aylin [Department of Chemistry, Faculty of Science, Gazi University, Teknikokullar (Turkey)], email: aytaca@gazi.edu.tr

    2011-07-01

    This study concerns the oxidation mechanism of hydrogen sulfide and a fuel cell; acidic peroxide is used as the oxidant and basic hydrogen sulfide is the fuel. A solid state H2S/H2O2 stable fuel cell was produced at room temperature. A cell potential of 0.85 V was reached; this is quite remarkable in comparison to the H2S/O2 fuel cell potential of 0.85 V obtained at 850-1000 degree celsius. The hydrogen sulfide goes through an oxidation reaction in the alkaline fuel cell (H2S/H2O2 fuel cell) which opens up the possibility of using the cheaper nickel as a catalyst. As a result, the fuel cell becomes a potentially low cost technology. A further benefit from using H2S as the alkaline liquid H2S/H2O2 fuel cell, is that sulfide ions are oxidized at the anode, releasing electrons. Sulfur produced reacts with the other sulfide ions and forms disulfide and polysulfide ions in basic electrolytes (such as Black Sea water).

  12. The Pattern of Distribution of Peroxidase and H2O2 in Hypocotyls of Pumpkin irradiated with Gamma Ray

    International Nuclear Information System (INIS)

    Wi, Seung Gon; Chung, Byung Yeoup; Kim, Jae Sung; Kim, Jin Hong; Lee, Ju Woon; Baek, Myung Hwa; Chae, Hyo Seok

    2005-01-01

    Gamma radiation, one of ionizing radiations, has been reported to affect the morphological, anatomical, biochemical and physiological changes of plants at different dose levels. These effects at high level include inhibition in plant growth. Peroxidases (PODs) are mainly participations the process of lignification on the cell wall and protect the cell organelles in cytosol against the oxidative stresses by ROS (reactive oxygen species). Hydrogen peroxide (ROS) is normal metabolite in aerobic cells and the physiological steady concentrations (between 10 -7 and 10 -9 ) are not particularly cytotoxic. When these concentrations are increased by ionizing radiation, they lead to cell lethality. Thus radiation-induced H 2 O 2 may appear as an important agent causing cell damage. In this study, a polyclonal antibody against peroxidase and cerium chloride as a trapping agent for H 2 O 2 were used to obtain for better information on the occurrence and distribution of POD and H 2 O 2 in the cytoplasm and walls of vascular bundle in hypocotyls of pumpkin

  13. [Protective effect of taxifolin on H2O2-induced 
H9C2 cell pyroptosis].

    Science.gov (United States)

    Ye, Yanqiong; Wang, Xiaoli; Cai, Qian; Zhuang, Jian; Tan, Xiaohua; He, Wei; Zhao, Mingyi

    2017-12-28

    To explore the effect of taxifolin on H2O2-induced pyroptosis in H9C2 cells and the possible mechanisms.
 Methods: The H9C2 cells was divided into 3 groups: a control group, a hydrogen peroxide (H2O2)group and a taxifolin group. The morphology of H9C2 cells was observed by inverted phase contrast microscope. The mitochondrial membrane potential was measured by JC-1 staining and flow cytometry. The alteration of the level of reactive oxygen species (ROS) was detected by specific mitochondrial probe. The protein levels of cysteinyl aspartate specific proteinase-1 (caspase-1)was determined by Western blot. The mRNA levels of interleukin-18 (IL-18), interleukin-1a (IL-1a), interleukin-1b (IL-1b), absent in melanoma 2 (AIM2), apoptosis-associated apeck-like protein (ASC), nucleotide-binding oligomerization domain-like receptor protein 3 (NLRP3)and nucleotide-binding oligomerization domain-like receptor family caspase recruitment domain-containing protein 4 (NLRC4) were determined by reverse transcription-polymerase chain reaction (RT-PCR).
 Results: Compared with the control group, the morphology of H9C2 cells obviously changed in the H2O2-treated group, which was guadually improved in the presence of taxifolin. Compared with the control group, the mitochondrial membrane potential was markedly decreased in the H2O2-treated cells, accompanied by the increase ofROS (both PH2O2 group, the mitochondrial membrane potential changes in the taxifolin group was increased while the ROS was decreased, with significant difference (both PH2O2-treated group were significantly increased (all PH2O2-induced H9C2 cell pyroptosis through inhibition of AIM2, NLRP3 and NLRC4 in flammasome.

  14. Electrochemical H2O2 biosensor composed of myoglobin on MoS2 nanoparticle-graphene oxide hybrid structure.

    Science.gov (United States)

    Yoon, Jinho; Lee, Taek; Bapurao G, Bharate; Jo, Jinhee; Oh, Byung-Keun; Choi, Jeong-Woo

    2017-07-15

    In this research, the electrochemical biosensor composed of myoglobin (Mb) on molybdenum disulfide nanoparticles (MoS 2 NP) encapsulated with graphene oxide (GO) was fabricated for the detection of hydrogen peroxide (H 2 O 2 ). Hybrid structure composed of MoS 2 NP and GO (GO@MoS 2 ) was fabricated for the first time to enhance the electrochemical signal of the biosensor. As a sensing material, Mb was introduced to fabricate the biosensor for H 2 O 2 detection. Formation and immobilization of GO@MoS 2 was confirmed by transmission electron microscopy, ultraviolet-visible spectroscopy, scanning electron microscopy, and scanning tunneling microscopy. Immobilization of Mb, and electrochemical property of biosensor were investigated by cyclic voltammetry and amperometric i-t measurements. Fabricated biosensor showed the electrochemical signal enhanced redox current as -1.86μA at an oxidation potential and 1.95μA at a reduction potential that were enhanced relative to those of electrode prepared without GO@MoS 2 . Also, this biosensor showed the reproducibility of electrochemical signal, and retained the property until 9 days from fabrication. Upon addition of H 2 O 2 , the biosensor showed enhanced amperometric response current with selectivity relative to that of the biosensor prepared without GO@MoS 2 . This novel hybrid material-based biosensor can suggest a milestone in the development of a highly sensitive detecting platform for biosensor fabrication with highly sensitive detection of target molecules other than H 2 O 2 . Copyright © 2016 Elsevier B.V. All rights reserved.

  15. Zn-Fe-CNTs catalytic in situ generation of H2O2 for Fenton-like degradation of sulfamethoxazole.

    Science.gov (United States)

    Liu, Yong; Fan, Qin; Wang, Jianlong

    2018-01-15

    A novel Fenton-like catalyst (Zn-Fe-CNTs) capable of converting O 2 to H 2 O 2 and further to OH was prepared through infiltration fusion method followed by chemical replacement in argon atmosphere. The catalyst was characterized by SEM, EDS, TEM, XRD and XPS. The reaction between Zn-Fe-CNTs and O 2 in aqueous solution could generate H 2 O 2 in situ, which was further transferred to OH. The Fenton-like degradation of sulfamethoxazole (SMX) using Zn-Fe-CNTs as catalyst was evaluated. The results indicated that Zn-Fe-CNTs had a coral porous structure with a BET area of 51.67m 2 /g, exhibiting excellent adsorption capacity for SMX, which enhanced its degradation. The particles of Zn 0 and Fe 0 /Fe 2 O 3 were observed on the surface of Zn-Fe-CNTs. The mixture of Zn 0 and CNTs could reduce O 2 into H 2 O 2 by micro-electrolysis and Fe 0 /Fe 2 O 3 could catalyze in-situ generation of H 2 O 2 to produce OH through Fenton-like process. When initial pH=1.5, T=25°C, O 2 flow rate=400mL/min, Zn-Fe-CNTs=0.6g/L, SMX=25mg/L and reaction time=10min, the removal efficiency of SMX and TOC was 100% and 51.3%, respectively. The intermediates were detected and the possible pathway of SMX degradation and the mechanism of Zn-Fe-CNTs/O 2 process were tentatively proposed. Copyright © 2017 Elsevier B.V. All rights reserved.

  16. Cosmetic wastewater treatment by the ZVI/H2O2 process.

    Science.gov (United States)

    Bogacki, Jan; Marcinowski, Piotr; Zapałowska, Ewa; Maksymiec, Justyna; Naumczyk, Jeremi

    2017-10-01

    The ZVI/H 2 O 2 process was applied for cosmetic wastewater treatment. Two commercial zero-valent iron (ZVI) types with different granulations were chosen: Hepure Ferrox PRB and Hepure Ferrox Target. In addition, the pH and stirring method influence on ZVI/H 2 O 2 process efficiency was studied. During the ZVI and ZVI/H 2 O 2 processes, linear Fe ions concentration increase was observed. The addition of H 2 O 2 significantly accelerated the iron dissolution process. The highest COD removal was obtained using finer ZVI (Hepure Ferrox Target) for doses of reagents ZVI/H 2 O 2 1500/1600 mg/L, in a H 2 O 2 /COD weight ratio 2:1, at pH 3.0 with stirring on a magnetic stirrer. After 120 min of the process, 84.0% COD removal (from 796 to 127 mg/L) was achieved. It was found that the efficiency of the process depends, as in the case of the Fenton process, on the ratio of the reagents (ZVI/H 2 O 2 ) and their dose in relation to the COD (H 2 O 2 /COD) but does not depend on the dose of the iron itself. Statistical analysis confirms that COD removal efficiency depends primarily on H 2 O 2 /COD ratio and ZVI granulation, but ZVI dose influence is not statistically significant. The head space, solid-phase microextraction, gas chromatography, mass spectrometry results confirm high efficiency of the ZVI/H 2 O 2 process.

  17. H2O2 Production in Species of the Lactobacillus acidophilus Group: a Central Role for a Novel NADH-Dependent Flavin Reductase

    NARCIS (Netherlands)

    Hertzberger, R.; Arents, J.; Dekker, H.L.; Pridmore, R.D.; Gysler, C.; Kleerebezem, M.; Mattos, de M.J.T.

    2014-01-01

    Hydrogen peroxide production is a well-known trait of many bacterial species associated with the human body. In the presence of oxygen, the probiotic lactic acid bacterium Lactobacillus johnsonii NCC 533 excretes up to 1 mM H2O2, inducing growth stagnation and cell death. Disruption of genes

  18. H2O2 Production in Species of the Lactobacillus acidophilus Group : A Central Role for a Novel NADH-Dependent Flavin Reductase

    NARCIS (Netherlands)

    Hertzberger, R.; Arents, J.; Dekker, H.L.; Pridmore, D.; Gysler, C.; Kleerebezem, M.; Teixeira de Mattosa, M.J.

    2014-01-01

    Hydrogen peroxide production is a well-known trait of many bacterial species associated with the human body. In the presence of oxygen, the probiotic lactic acid bacterium Lactobacillus johnsonii NCC 533 excretes up to 1 mM H2O2, inducing growth stagnation and cell death. Disruption of genes

  19. Thermal Reactions of H2O2 on Icy Satellites and Small Bodies: Descent with Modification?

    Science.gov (United States)

    Hudson, Reggie L.; Loeffler, Mark J.

    2012-01-01

    Magnetospheric radiation drives surface and near-surface chemistry on Europa, but below a few meters Europa's chemistry is hidden from direct observation . As an example, surface radiation chemistry converts H2O and SO2 into H2O2 and (SO4)(sup 2-), respectively, and these species will be transported downward for possible thermally-driven reactions. However, while the infrared spectra and radiation chemistry of H2O2-containing ices are well documented, this molecule's thermally-induced solid-phase chemistry has seldom been studied. Here we report new results on thermal reactions in H2O + H2O2 + SO2 ices at 50 - 130 K. As an example of our results, we find that warming H2O + H2O2 + SO2 ices promotes SO2 oxidation to (SO4)(sup 2-). These results have implications for the survival of H2O2 as it descends, with modification, towards a subsurface ocean on Europa. We suspect that such redox chemistry may explain some of the observations related to the presence and distribution of H2O2 across Europa's surface as well as the lack of H2O2 on Ganymede and Callisto.

  20. Decoloration Kinetics of Waste Cooking Oil by 60Co γ-ray/H2O2

    Science.gov (United States)

    Xiang, Yulin; Xiang, Yuxiu; Wang, Lipeng

    2016-03-01

    In order to decolorize, waste cooking oil, a dark red close to black solution from homes and restaurants, was subjected to 60Co γ-ray/H2O2 treatment. By virtue of UV/Vis spectrophotometric method, the influence of Gamma irradiation to decoloration kinetics and rate constants of the waste cooking oil in the presence of H2O2 was researched. In addition, the influence of different factors such as H2O2 concentration and irradiation dose on the decoloration rate of waste cooking oil was investigated. Results indicated that the decoloration kinetics of waste cooking oil conformed to the first-order reaction. The decoloration rate increased with the increase of irradiation dose and H2O2 concentration. Saponification analysis and sensory evaluation showed that the sample by 60Co γ-ray/H2O2 treatment presented better saponification performance and sensory score. Furthermore, according to cost estimate, the cost of the 60Co γ-ray/H2O2 was lower and more feasible than the H2O2 alone for decoloration of waste cooking oil.

  1. Advanced oxidation of hypophosphite and phosphite using a UV/H2O2 process.

    Science.gov (United States)

    Liu, Peng; Li, Chaolin; Liang, Xingang; Xu, Jianhui; Lu, Gang; Ji, Fei

    2013-01-01

    The oxidation of hypophosphite and phosphite in an aqueous solution by an ultraviolet (UV)/H2O2 process was studied in this work. The reactions were performed in a lab-scale batch photoreactor. The effect of different parameters such as H2O2 dosage, H2O2 feeding mode and the initial pH of the solution on the oxidation efficiency of the process was investigated. The results indicated that the UV/H2O2 process could effectively oxidize hypophosphite and phosphite in both synthesized and real wastewater. However, neither H2O2 nor UV alone was able to appreciably oxidize the hypophosphite or phosphite. The best way of feeding H2O2 was found to be 'continuous feeding', which maximized the reaction rate. It was also found that the process presented a wide range of applicable initial pH (5-11). When treating real rinse-wastewater, which was obtained from the electroless nickel plating industry, both hypophosphite and phosphite were completely oxidized within 60 min, and by extending by another 30 min, over 90% of the chemical oxygen demand removal was obtained. Without any additional catalyst, the UV/H2O2 process can oxidize hypophosphite and phosphite to easily removable phosphate. It is really a powerful and environmentally friendly treatment method for the wastewater containing hypophosphite and phosphite.

  2. The Synergistic Priming Effect of Exogenous Salicylic Acid and H2O2 on Chilling Tolerance Enhancement during Maize (Zea mays L.) Seed Germination.

    Science.gov (United States)

    Li, Zhan; Xu, Jungui; Gao, Yue; Wang, Chun; Guo, Genyuan; Luo, Ying; Huang, Yutao; Hu, Weimin; Sheteiwy, Mohamed S; Guan, Yajing; Hu, Jin

    2017-01-01

    Chilling stress is an important constraint for maize seedling establishment in the field. To examine the role of salicylic acid (SA) and hydrogen peroxide (H 2 O 2 ) in response to chilling stress, we investigated the effects of seed priming with SA, H 2 O 2 , and SA+H 2 O 2 combination on maize resistance under chilling stress (13°C). Priming with SA, H 2 O 2 , and especially SA+H 2 O 2 shortened seed germination time and enhanced seed vigor and seedling growth as compared with hydropriming and non-priming treatments under low temperature. Meanwhile, SA+H 2 O 2 priming notably increased the endogenous H 2 O 2 and SA content, antioxidant enzymes activities and their corresponding genes ZmPAL, ZmSOD4, ZmAPX2, ZmCAT2 , and ZmGR expression levels. The α-amylase activity was enhanced to mobilize starch to supply metabolites such as soluble sugar and energy for seed germination under chilling stress. In addition, the SA+H 2 O 2 combination positively up-regulated expressions of gibberellic acid (GA) biosynthesis genes ZmGA20ox1 and ZmGA3ox2 , and down-regulated GA catabolism gene ZmGA2ox1 expression; while it promoted GA signaling transduction genes expressions of ZmGID1 and ZmGID2 and decreased the level of seed germination inhibitor gene ZmRGL2 . The abscisic acid (ABA) catabolism gene ZmCYP707A2 and the expressions of ZmCPK11 and ZmSnRK2.1 encoding response receptors in ABA signaling pathway were all up-regulated. These results strongly suggested that priming with SA and H 2 O 2 synergistically promoted hormones metabolism and signal transduction, and enhanced energy supply and antioxidant enzymes activities under chilling stress, which were closely relevant with chilling injury alleviation and chilling-tolerance improvement in maize seed. Highlights: Seed germination and seedling growth were significantly improved under chilling stress by priming with SA+H 2 O 2 combination, which was closely relevant with the change of reactive oxygen species, metabolites and

  3. Effects of pH and H2O2 on ammonia, nitrite, and nitrate transformations during UV254nm irradiation: Implications to nitrogen removal and analysis.

    Science.gov (United States)

    Wang, Junli; Song, Mingrui; Chen, Baiyang; Wang, Lei; Zhu, Rongshu

    2017-10-01

    In order to achieve better removal and analyses of three dissolved inorganic nitrogen (DIN) species via ultraviolet-activated hydrogen peroxide (UV/H 2 O 2 ) process, this study systematically investigated the rates of photo-oxidations of ammonia/ammonium (NH 3 /NH 4 + ) and nitrite (NO 2 - ) as well as the photo-reduction of nitrate (NO 3 - ) at varying pH and H 2 O 2 conditions. The results showed that the mass balances of nitrogen were maintained along irradiation despite of interconversions of DIN species, suggesting that no nitrogen gas (N 2 ) or other nitrogen-containing compound was formed. NH 3 was more reactive than NH 4 + with hydroxyl radical (OH), and by a stepwise H 2 O 2 addition method NH 3 /NH 4 + can be completely converted to NO x - ; NO 2 - underwent rapid oxidation to form NO 3 - when H 2 O 2 was present, suggesting that it is an intermediate compound linking NH 3 /NH 4 + and NO 3 - ; but once H 2 O 2 was depleted, NO 3 - can be gradually photo-reduced back to NO 2 - at high pH conditions. Other than H 2 O 2 , the transformation kinetics of DINs were all dependent on pH, but to varying aspects and extents: the NH 3 photo-oxidation favored a pH of 10.3, which fell within the pK a values of NH 4 + (9.24) and H 2 O 2 (11.6); the NO 3 - photo-reduction increased with increasing pH provided that it exceeds the pK a of peroxynitrous acid (6.8); while the NO 2 - photo-oxidation remained stable unless the pH neared the pK a of H 2 O 2 (11.6). The study thereby demonstrates a picture of the evolutions of DIN species together during UV/H 2 O 2 irradiation process, and for the first time presents a method to achieve complete conversion of NH 4 + to NO 3 - with UV/H 2 O 2 process. Copyright © 2017 Elsevier Ltd. All rights reserved.

  4. Pinocembrin Suppresses H2O2-Induced Mitochondrial Dysfunction by a Mechanism Dependent on the Nrf2/HO-1 Axis in SH-SY5Y Cells.

    Science.gov (United States)

    de Oliveira, Marcos Roberto; da Costa Ferreira, Gustavo; Brasil, Flávia Bittencourt; Peres, Alessandra

    2018-02-01

    Mitochondria are susceptible to redox impairment, which has been associated with neurodegeneration. These organelles are both a source and target of reactive species. In that context, there is increasing interest in finding natural compounds that modulate mitochondrial function and mitochondria-related signaling in order to prevent or to treat diseases involving mitochondrial impairment. Herein, we investigated whether and how pinocembrin (PB) would prevent mitochondrial dysfunction elicited by the exposure of human neuroblastoma SH-SY5Y cells to hydrogen peroxide (H 2 O 2 ). PB (25 μM) was administrated for 4 h before H 2 O 2 treatment (300 μM for 24 h). PB prevented H 2 O 2 -induced loss of cell viability mitochondrial depolarization in SH-SY5Y cells. PB also attenuated redox impairment in mitochondrial membranes. The production of superoxide anion radical (O 2 -• ) and nitric oxide (NO • ) was alleviated by PB in cells exposed to H 2 O 2 . PB suppressed the H 2 O 2 -induced inhibition of the tricarboxylic acid (TCA) cycle enzymes aconitase, α-ketoglutarate dehydrogenase, and succinate dehydrogenase. Furthermore, PB induced anti-inflammatory effects by abolishing the H 2 O 2 -dependent activation of the nuclear factor-κB (NF-κB) and upregulation of interleukin-1β (IL-1β) and tumor necrosis factor-α (TNF-α). The PB-induced antioxidant and anti-inflammatory effects are dependent on the heme oxygenate-1 (HO-1) enzyme and on the activation of the transcription factor nuclear factor erythroid 2-related factor 2 (Nrf2), since HO-1 inhibition (with 0.5 μM ZnPP IX) or Nrf2 silencing (with small interfering RNA (siRNA)) abolished the effects of PB. Overall, PB afforded cytoprotection by the Nrf2/HO-1 axis in H 2 O 2 -treated SH-SY5Y cells.

  5. Peroxy defects in Rocks and H2O2 formation on the early Earth

    Science.gov (United States)

    Gray, A.; Balk, M.; Mason, P.; Freund, F.; Rothschild, L.

    2013-12-01

    An oxygen-rich atmosphere appears to have been a prerequisite for complex life to evolve on Earth and possibly elsewhere in the Universe. The question is still shrouded in uncertainty how free oxygen became available on the early Earth. Here we study processes of peroxy defects in silicate minerals which, upon weathering, generate mobilized electronic charge carriers resulting in oxygen formation in an initially anoxic subsurface environment. Reactive Oxygen Species (ROS) are precursors to molecular oxygen during this process. Due to their toxicity they may have strongly influenced the evolution of life. ROS are generated during hydrolysis of peroxy defects, which consist of pairs of oxygen anions. A second pathway for formation occurs during (bio) transformations of iron sulphide minerals. ROS are produced and consumed by intracellular and extracellular reactions of Fe, Mn, C, N, and S species. We propose that despite an overall reducing or neutral oxidation state of the macroenvironment and the absence of free O2 in the atmosphere, microorganisms on the early Earth had to cope with ROS in their microenvironments. They were thus under evolutionary pressure to develop enzymatic and other defenses against the potentially dangerous, even lethal effects of ROS and oxygen. We have investigated how oxygen might be released through weathering and test microorganisms in contact with rock surfaces. Our results show how early Life might have adapted to oxygen. Early microorganisms must have "trained" to detoxify ROS prior to the evolution of aerobic metabolism and oxygenic photosynthesis. A possible way out of this dilemma comes from a study of igneous and high-grade metamorphic rocks, whose minerals contain a small but significant fraction of oxygen anions in the valence state 1- , forming peroxy links of the type O3Si-OO-SiO3 [1, 2]. As water hydrolyzes the peroxy links hydrogen peroxide, H2O2, forms. Continued experimental discovery of H2O2 formation at rock

  6. Application of H2O and UV/H2O2 processes for enhancing the biodegradability of reactive black 5 dye.

    Science.gov (United States)

    Kalpana, S Divya; Kalyanaraman, Chitra; Gandhi, N Nagendra

    2011-07-01

    Leather processing is a traditional activity in India during which many organic and inorganic chemicals are added while part of it is absorbed by the leather, the remaining chemicals are discharged along with the effluent. The effluent contains both easily biodegradable and not easily biodegradable synthetic organics like dyes, syntans. Easily biodegradable organics are removed in the existing biological treatment units whereas synthetic organics present in the wastewater are mostly adsorbed over the microbes. As the tannery effluent contains complex chemicals, it is difficult to ascertain the degradation of specific pollutants. To determine the increase in the biodegradability, one of the complex and synthetic organic chemical like dye used in the tanning operation was selected for Advanced Oxidation Process (AOPs) treatment for cleaving complex organics and its subsequent treatment in aerobic process. In the present study, Reactive Black 5 Dye used in the tanning operation was selected for Hydrogen Peroxide (H2O2) and UV/H2O2 pre-treatment for different operating conditions like pH, contact time and different volume of H2O2. A comparison was made between the untreated, Hydrogen Peroxide (H2O2) and UV/H2O2 treated effluent in order to ascertain the influence of AOP on the improvement of biodegradability of effluent. An increase in the BOD5/COD ratio from 0.21 to 0.435 was achieved in the UV/H2O2 pre-treatment process. This pre-treated effluent was further subjected to aerobic process. Biochemical Oxygen Demand (BOD5) and Chemical Oxygen Demand (COD) removal efficiency of the UV/H2O2 pre-treated dye solution in the aerobic process was found to be 86.39% and 77.82% when compared to 52.43% of BOD5 and 51.55% of COD removal efficiency without any pre-treatment. Hence from these results, to increase the biodegradability of Reactive Black 5 dye pre-treatment methods like H2O2 and UV/H2O2 can be used prior to biological treatment process.

  7. Flower-Like Nanoparticles of Pt-BiIII Assembled on Agmatine Sulfate Modified Glassy Carbon Electrode and Their Electrocatalysis of H2O2

    Science.gov (United States)

    Xiao, Mingshu; Yan, Yuhua; Feng, Kai; Tian, Yanping; Miao, Yuqing

    2015-04-01

    A new electrochemical technique to detect hydrogen peroxide (H2O2) was developed. The Pt nanoparticles and BiIII were subsequently assembled on agmatine sulfate (AS) modified glassy carbon electrode (GCE) and the prepared GCE-AS-Pt-BiIII was characterized by scanning electron microscopy (SEM) with result showing that the flower-like nanostructure of Pt-BiIII was yielded. Compared with Pt nanoparticles, the flower-like nanostructure of Pt-BiIII greatly enhanced the electrocatalysis of GCE-AS-Pt-BiIII towards H2O2, which is ascribed to more Pt-OH obtained on GCE-AS-Pt-BiIII surface for the presence of BiIII. Based on its high electrocatalysis, GCE-AS-Pt-BiIII was used to determine the content of H2O2 in the sample of sheet bean curd with standard addition method. Meantime, its electrocatalytic activity also was studied.

  8. Facile synthesis of morphology-controlled Co3O4 nanostructures through solvothermal method with enhanced catalytic activity for H2O2 electroreduction

    Science.gov (United States)

    Cheng, Kui; Cao, Dianxue; Yang, Fan; Xu, Yang; Sun, Gaohui; Ye, Ke; Yin, Jinling; Wang, Guiling

    2014-05-01

    Hydrogen peroxide (H2O2) replaced oxygen (O2) as oxidant has been widely investigated due to its faster reduction kinetics, easier storage and handling than gaseous oxygen. The main challenge of using H2O2 as oxidant is the chemical decomposition. In this article, by using different C2H5OH/H2O volume ratio as the solvent, Co3O4 with different morphologies (nanosheet, nanowire, ultrafine nanowire net, nanobelts, and honeycomb-like) direct growth on Ni foam are synthesized via a simple solvothermal method for the first time. Results show that the introduction of ethanol could obviously improve the catalytic performance toward H2O2 electroreduction. The sample prepared in the solution with the C2H5OH/H2O volume ratio of 1:2 shows the best catalytic performance among the five samples and a current density of 0.214 A cm-2 is observed in 3.0 mol L-1 KOH + 0.5 mol L-1 H2O2 at -0.4 V (vs. Ag/AgCl KCl), which is much larger than that on the other metal oxides reported previously, almost comparable with the precious metals. This electrode of Co3O4 directly grown on Ni foam has superior mass transport property, which combining with its low-cost and facile preparation, make it a promising electrode for fuel cell using H2O2 as the oxidant.

  9. Detection of pH and Enzyme-Free H2O2 Sensing Mechanism by Using GdO x Membrane in Electrolyte-Insulator-Semiconductor Structure.

    Science.gov (United States)

    Kumar, Pankaj; Maikap, Siddheswar; Qiu, Jian-Tai; Jana, Surajit; Roy, Anisha; Singh, Kanishk; Cheng, Hsin-Ming; Chang, Mu-Tung; Mahapatra, Rajat; Chiu, Hsien-Chin; Yang, Jer-Ren

    2016-12-01

    A 15-nm-thick GdO x membrane in an electrolyte-insulator-semiconductor (EIS) structure shows a higher pH sensitivity of 54.2 mV/pH and enzyme-free hydrogen peroxide (H2O2) detection than those of the bare SiO2 and 3-nm-thick GdO x membranes for the first time. Polycrystalline grain and higher Gd content of the thicker GdO x films are confirmed by transmission electron microscopy (TEM) and X-ray photo-electron spectroscopy (XPS), respectively. In a thicker GdO x membrane, polycrystalline grain has lower energy gap and Gd(2+) oxidation states lead to change Gd(3+) states in the presence of H2O2, which are confirmed by electron energy loss spectroscopy (EELS). The oxidation/reduction (redox) properties of thicker GdO x membrane with higher Gd content are responsible for detecting H2O2 whereas both bare SiO2 and thinner GdO x membranes do not show sensing. A low detection limit of 1 μM is obtained due to strong catalytic activity of Gd. The reference voltage shift increases with increase of the H2O2 concentration from 1 to 200 μM owing to more generation of Gd(3+) ions, and the H2O2 sensing mechanism has been explained as well.

  10. The fluxes of H2O2 and O2 can be used to evaluate seed germination and vigor of Caragana korshinskii.

    Science.gov (United States)

    Li, Jiaguo; Wang, Yu; Pritchard, Hugh W; Wang, Xiaofeng

    2014-06-01

    Seed deterioration is detrimental to plant germplasm conservation, and predicting seed germination and vigor with reliability and sensitivity means is urgently needed for practical problems. We investigated the link between hydrogen peroxide (H2O2) flux, oxygen influx and seed vigor of Caragana korshinskii by the non-invasive micro-test technique (NMT). Some related physiological and biochemical changes in seeds were also determined to further explain the changes in the molecular fluxes. The results showed that there was a good linear relationship between germination and H2O2 flux, and that O2 influx was more suitable for assessing seed vigor. H2O2 flux changed relatively little initially, mainly affected by antioxidants (APX, CAT and GSH) and H2O2 content; afterward, the efflux increased more and more rapidly due to high membrane permeability. With the damage of mitochondrial respiration and membrane integrity, O2 influx was gradually reduced. We propose that monitoring H2O2 and O2 fluxes by NMT may be a reliable and sensitive method to evaluate seed germination and vigor.

  11. Enhancement of catalase activity by repetitive low-grade H2O2 exposures protects fibroblasts from subsequent stress-induced apoptosis

    International Nuclear Information System (INIS)

    Sen, Prosenjit; Mukherjee, Sebanti; Bhaumik, Gayaram; Das, Pradeep; Ganguly, Sandipan; Choudhury, Nandini; Raha, Sanghamitra

    2003-01-01

    Exposure of Chinese hamster V79 fibroblasts to mild and repetitive H 2 O 2 doses in culture for 15 weeks produced no change in lipid peroxidation status, GSH/GSSG ratio and glutathione peroxidase activity of these cells (VST cells). In contrast, in VST cells catalase levels underwent a prominent increase which could be significantly inhibited and brought down to control levels after treatment with the catalase inhibitor 3-aminotriazole (3-AT). When control (VC) cells were exposed to UV radiation (UVC 5 J/m 2 ) or H 2 O 2 (7.5 mM, 15 min), intracellular reactive oxygen species (ROS) levels rose prominently with significant activation of caspase-3. Marked nuclear fragmentation and lower cell viability were also noted in these cells. In contrast, VST cells demonstrated a significantly lower ROS level, an absence of nuclear fragmentation and an unchanged caspase-3 activity after exposure to UVC or H 2 O 2 . Cell viability was also significantly better preserved in VST cells than VC cells after UV or H 2 O 2 exposures. Following 3-AT treatment of VST cells, UVC radiation or H 2 O 2 brought about significantly higher elevations in intracellular ROS, increases in caspase-3 activity, significantly lowered cell viability and marked nuclear fragmentation, indicating the involvement of high catalase levels in the cytoprotective effects of repetitive stress. Therefore, upregulation of the antioxidant defense after repetitive oxidative stress imparted a superior ability to cope with subsequent acute stress and escape apoptotic death and loss of viability

  12. Synthesis of CuO nanoflower and its application as a H2O2 sensor

    Indian Academy of Sciences (India)

    Administrator

    CuO; nanoflowers; electrochemical; H2O2. 1. Introduction. Cupric oxide (CuO) is an important transition metal oxide ... several high temperature superconductors and giant mag- ... precipitate was washed with ethanol and distilled water.

  13. [Mechanism and performance of styrene oxidation by O3/H2O2].

    Science.gov (United States)

    He, Jue-Cong; Huang, Qian-Ru; Ye, Qi-Hong; Luo, Yu-Wei; Zhang, Zai-Li; Fan, Qing-Juan; Wei, Zai-Shan

    2013-10-01

    It can produce a large number of free radicals in O3/H2O2, system, ozone and free radical coupling oxidation can improve the styrene removal efficiency. Styrene oxidation by O3/H2O2 was investigated. Ozone dosage, residence time, H2o2 volume fraction, spray density and molar ratio of O3/C8H8 on styrene removal were evaluated. The experimental results showed that styrene removal efficiency achieved 85.7%. The optimal residence time, H2O2, volume fraction, spray density and O3/C8H8 molar ratio were 20. 6 s, 10% , 1.72 m3.(m2.h)-1 and 0.46, respectively. The gas-phase degradation intermediate products were benzaldehyde(C6H5CHO) and benzoic acid (C6H5 COOH) , which were identified by means of gas chromatography-mass spectrometry(GC-MS). The degradation mechanism of styrene is presented.

  14. Post-treatment of biologically treated wastewater containing organic contaminants using a sequence of H2O2 based advanced oxidation processes: photolysis and catalytic wet oxidation.

    Science.gov (United States)

    Rueda-Márquez, J J; Sillanpää, M; Pocostales, P; Acevedo, A; Manzano, M A

    2015-03-15

    In this paper the feasibility of a multi-barrier treatment (MBT) for the regeneration of synthetic industrial wastewater (SIWW) was evaluated. Industrial pollutants (orange II, phenol, 4-chlorophenol and phenanthrene) were added to the effluent of municipal wastewater treatment plant. The proposed MBT begins with a microfiltration membrane pretreatment (MF), followed by hydrogen peroxide photolysis (H2O2/UVC) and finishing, as a polishing step, with catalytic wet peroxide oxidation (CWPO) using granular activated carbon (GAC) at ambient conditions. During the microfiltration step (0.7 μm) the decrease of suspended solids concentration, turbidity and Escherichia coli in treated water were 88, 94 and 99%, respectively. Also, the effluent's transmittance (254 nm) was increased by 14.7%. Removal of more than 99.9% of all added pollutants, mineralization of 63% of organic compounds and complete disinfection of total coliforms were reached during the H2O2/UVC treatment step (H2O2:TOC w/w ratio = 5 and an UVC average dose accumulated by wastewater 8.80 WUVC s cm(-2)). The power and efficiency of the lamp, the water transmittance and photoreactor geometry are taken into account and a new equation to estimate the accumulated dose in water is suggested. Remaining organic pollutants with a higher oxidation state of carbon atoms (+0.47) and toxic concentration of residual H2O2 were present in the effluent of the H2O2/UVC process. After 2.3 min of contact time with GAC at CWPO step, 90 and 100% of total organic carbon and residual H2O2 were removed, respectively. Also, the wastewater toxicity was studied using Vibrio fischeri and Sparus aurata larvae. The MBT operational and maintenance costs (O&M) was estimated to be 0.59 € m(-3). Copyright © 2015 Elsevier Ltd. All rights reserved.

  15. Glucose acutely reduces cytosolic and mitochondrial H2O2 in rat pancreatic beta-cells.

    Science.gov (United States)

    Deglasse, Jean-Philippe; Roma, Leticia Prates; Pastor-Flores, Daniel; Gilon, Patrick; Dick, Tobias P; Jonas, Jean-Christophe

    2018-05-14

    Whether H2O2 contributes to the glucose-dependent stimulation of insulin secretion by pancreatic β-cells is highly controversial. We used two H2O2-sensitive probes, roGFP2-Orp1 and HyPer with its pH-control SypHer, to test the acute effects of glucose, monomethylsuccinate, leucine with glutamine, and α-ketoisocaproate, on β-cell cytosolic and mitochondrial H2O2 concentrations. We then tested the effects of low H2O2 and menadione concentrations on insulin secretion. RoGFP2-Orp1 was more sensitive than HyPer to H2O2 (response at 2-5 vs. 10µM) and less pH-sensitive. Under control conditions, stimulation with glucose reduced mitochondrial roGFP2-Orp1 oxidation without affecting cytosolic roGFP2-Orp1 and HyPer fluorescence ratios, except for the pH-dependent effects on HyPer. However, stimulation with glucose decreased the oxidation of both cytosolic probes by 15µM exogenous H2O2. The glucose effects were not affected by overexpression of catalase, mitochondrial catalase or superoxide dismutase 1 and 2. They followed the increase in NAD(P)H autofluorescence, were maximal at 5mM glucose in the cytosol and 10mM glucose in the mitochondria, and were partly mimicked by the other nutrients. Exogenous H2O2 (1-15µM) did not affect insulin secretion. By contrast, menadione (1-5µM) did not increase basal insulin secretion but reduced the stimulation of insulin secretion by 20mM glucose. Subcellular changes in β-cell H2O2 levels are better monitored with roGFP2-Orp1 than HyPer/SypHer. Nutrients acutely lower mitochondrial H2O2 levels in β-cells and promote degradation of exogenously supplied H2O2 in both cytosolic and mitochondrial compartments. The glucose-dependent stimulation of insulin secretion occurs independently of a detectable increase in β-cell cytosolic or mitochondrial H2O2 levels.

  16. Free radical behaviours during methylene blue degradation in the Fe2+/H2O2 system.

    Science.gov (United States)

    Wang, Zhonghua; Zhao, Haiqian; Qi, Hanbing; Liu, Xiaoyan; Liu, Yang

    2017-12-22

    Behaviours of the free radicals during the methylene blue (MB) oxidation process in the Fe 2+ /H 2 O 2 system were studied to reveal the reason for the low utilization efficiency of H 2 O 2 . The roles of [Formula: see text], [Formula: see text] and [Formula: see text] radicals were proven to be different in the MB oxidation process. The results showed that [Formula: see text] radicals had a strong ability to oxidize MB; however, they were not the main active substances for MB degradation due to the low concentration in the traditional Fe 2+ /H 2 O 2 system. [Formula: see text] radicals could not oxidize MB. [Formula: see text] radicals were the main active substances for MB oxidation. In the short initial stage, the utilization efficiency of H 2 O 2 was high, because the generation rate of [Formula: see text] was much higher than that of [Formula: see text]. More [Formula: see text] radicals were involved in the MB oxidation reaction. In the long deceleration stage (after the short initial stage), a large amount of H 2 O 2 was consumed, but the amount of oxidized MB was very small. Most of the [Formula: see text] radicals were consumed via the rapid useless reaction between [Formula: see text] and [Formula: see text] in this stage, resulting in the serious useless consumption of H 2 O 2 . It is a feasible method to improve the utilization efficiency of H 2 O 2 by adding suitable additives into the Fe 2+ /H 2 O 2 system to weaken the useless reaction between [Formula: see text] and [Formula: see text].

  17. Drosophila TRPA1 isoforms detect UV light via photochemical production of H2O2

    Science.gov (United States)

    Guntur, Ananya R.; Gu, Pengyu; Takle, Kendra; Chen, Jingyi; Xiang, Yang; Yang, Chung-Hui

    2015-01-01

    The transient receptor potential A1 (TRPA1) channel is an evolutionarily conserved detector of temperature and irritant chemicals. Here, we show that two specific isoforms of TRPA1 in Drosophila are H2O2 sensitive and that they can detect strong UV light via sensing light-induced production of H2O2. We found that ectopic expression of these H2O2-sensitive Drosophila TRPA1 (dTRPA1) isoforms conferred UV sensitivity to light-insensitive HEK293 cells and Drosophila neurons, whereas expressing the H2O2-insensitive isoform did not. Curiously, when expressed in one specific group of motor neurons in adult flies, the H2O2-sensitive dTRPA1 isoforms were as competent as the blue light-gated channelrhodopsin-2 in triggering motor output in response to light. We found that the corpus cardiacum (CC) cells, a group of neuroendocrine cells that produce the adipokinetic hormone (AKH) in the larval ring gland endogenously express these H2O2-sensitive dTRPA1 isoforms and that they are UV sensitive. Sensitivity of CC cells required dTRPA1 and H2O2 production but not conventional phototransduction molecules. Our results suggest that specific isoforms of dTRPA1 can sense UV light via photochemical production of H2O2. We speculate that UV sensitivity conferred by these isoforms in CC cells may allow young larvae to activate stress response—a function of CC cells—when they encounter strong UV, an aversive stimulus for young larvae. PMID:26443856

  18. Antioxidative potential of Duranta repens (linn.) fruits against H 2 O 2 ...

    African Journals Online (AJOL)

    The effects of Duranta repens fruits were investigated on H2O2 induced oxidative cell death to evaluate its antioxidative potential in vitro. HEK293T cells were treated with different concentrations [0-1000 ìg/ ml] of ethanol extract (E-Ex) and methanol extract (M-Ex) of D. repens for 24h, and then treated with 100 ìM H2O2 for ...

  19. The rate constant for the CO + H2O2 reaction

    DEFF Research Database (Denmark)

    Glarborg, Peter; Marshall, Paul

    2009-01-01

    The rate constant for the reaction CO + H2O2 -> HOCO + OH (R1) at 713 K is determined based on the batch reactor experiments of Baldwin et al. [ R. R. Baldwin, R. W. Walker, S. J. Webster, Combust. Flame 15 (1970) 167] on decomposition of H2O2 sensitized by CO. The value, k(1) (713 K) = 8.1 x 10...

  20. Cross Talk between H2O2 and Interacting Signal Molecules under Plant Stress Response

    Science.gov (United States)

    Saxena, Ina; Srikanth, Sandhya; Chen, Zhong

    2016-01-01

    It is well established that oxidative stress is an important cause of cellular damage. During stress conditions, plants have evolved regulatory mechanisms to adapt to various environmental stresses. One of the consequences of stress is an increase in the cellular concentration of reactive oxygen species, which is subsequently converted to H2O2. H2O2 is continuously produced as the byproduct of oxidative plant aerobic metabolism. Organelles with a high oxidizing metabolic activity or with an intense rate of electron flow, such as chloroplasts, mitochondria, or peroxisomes are major sources of H2O2 production. H2O2 acts as a versatile molecule because of its dual role in cells. Under normal conditions, H2O2 immerges as an important factor during many biological processes. It has been established that it acts as a secondary messenger in signal transduction networks. In this review, we discuss potential roles of H2O2 and other signaling molecules during various stress responses. PMID:27200043

  1. Cosmetic wastewater treatment using the Fenton, Photo-Fenton and H2O2/UV processes.

    Science.gov (United States)

    Marcinowski, Piotr P; Bogacki, Jan P; Naumczyk, Jeremi H

    2014-01-01

    Advanced Oxidation Processes (AOPs), such as the Fenton, photo-Fenton and H2O2/UV processes, have been investigated for the treatment of cosmetic wastewaters that were previously coagulated by FeCl3. The Photo-Fenton process at pH 3.0 with 1000/100 mg L(-1) H2O2/Fe(2+) was the most effective (74.0% Chemical Oxygen Demand (COD) removal). The Fenton process with 1200/500 mg L(-1) H2O2/Fe(2+) achieved a COD removal of 72.0%, and the H2O2/UV process achieved a COD removal of 47.0%. Spreading the H2O2 doses over time to obtain optimal conditions did not improve COD removal. The kinetics of the Fenton and photo-Fenton processes may be described by the following equation: d[COD]/dt = -a[COD] t(m) (t represents time and a and m are constants). The rate of COD removal by the H2O2/UV process may be described by a second-order reaction equation. Head Space, Solid-Phase MicroExtraction, Gas Chromatography and Mass Spectrometry (HS-SPME-GC-MS) were used to identify 48 substances in precoagulated wastewater. Among these substances, 26 were fragrances. Under optimal AOP conditions, over 99% of the identified substances were removed in 120 min.

  2. Bleaching of cotton fabric with tetraacetylhydrazine as bleach activator for H2O2.

    Science.gov (United States)

    Liu, Kai; Zhang, Xuan; Yan, Kelu

    2018-05-15

    Tetraacetylhydrazine (TH) as bleach activator for H 2 O 2 cotton bleaching was synthesized and characterized by 1 H NMR, 13 C NMR and MS spectra. TH has better solubility than that of TAED. The CIE whiteness index (WI), H 2 O 2 decomposition rate and bursting strength were employed to investigate the performance of H 2 O 2 /TH bleaching system. By addition of TH, WI and H 2 O 2 decomposition rate increased significantly at 70 °C. Bleaching temperature, NaHCO 3 concentration and bleaching time were also discussed in detail and the loss of bursting strength is not clear. By using benzenepentacarboxylic acid (BA) as a fluorescent probe for hydroxyl radical detection, the bleaching process of H 2 O 2 /TH system was investigated. Acetylhydrazine and diacetylhydrazine were also utilized to further confirm the process. In addition, bimolecular decomposition was investigated by using 9,10-dimethylanthracene (DMA) as fluorescent probe of 1 O 2 . Based on these experimental results, the bleaching mechanism of H 2 O 2 /TH system was proposed. Copyright © 2018 Elsevier Ltd. All rights reserved.

  3. Photochemical degradation of diethyl phthalate with UV/H2O2

    International Nuclear Information System (INIS)

    Xu Bin; Gao Naiyun; Sun Xiaofeng; Xia Shengji; Rui Min; Simonnot, Marie-Odile; Causserand, Christel; Zhao Jianfu

    2007-01-01

    The decomposition of diethyl phthalate (DEP) in water using UV-H 2 O 2 process was investigated in this paper. DEP cannot be effectively removed by UV radiation and H 2 O 2 oxidation alone, while UV-H 2 O 2 combination process proved to be effective and could degrade this compound completely. With initial concentration about 1.0 mg/L, more than 98.6% of DEP can be removed at time of 60 min under intensity of UV radiation of 133.9 μW/cm 2 and H 2 O 2 dosage of 20 mg/L. The effects of applied H 2 O 2 dose, UV radiation intensity, water temperature and initial concentration of DEP on the degradation of DEP have been examined in this study. Degradation mechanisms of DEP with hydroxyl radicals oxidation also have been discussed. Removal rate of DEP was sensitive to the operational parameters. A simple kinetic model is proposed which confirms to pseudo-first order reaction. There is a linear relationship between rate constant k and UV intensity and H 2 O 2 concentration

  4. Decolourisation of dye solutions by oxidation with H2O2 in the presence of modified activated carbons

    International Nuclear Information System (INIS)

    Santos, V.P.; Pereira, M.F.R.; Faria, P.C.C.; Orfao, J.J.M.

    2009-01-01

    The decolourisation of dye solutions by oxidation with H 2 O 2 , using activated carbon as catalyst, is studied. For this purpose, three different samples, mainly differing in the respective surface chemistries, were prepared and characterized. Moreover, this work involved three pH levels, corresponding to acid, neutral and alkaline solutions, and six dyes belonging to several classes. The catalytic decolourisation tests were performed in a laboratorial batch reactor. Adsorption on activated carbon and non-catalytic peroxidation kinetic experiments were also carried out in the same reactor, in order to compare the efficiencies of the three processes. The non-catalytic reaction is usually inefficient and, typically, adsorption presents a low level of decolourisation. In these cases, the combination of activated carbon with hydrogen peroxide may significantly enhance the process, since the activated carbon catalyses the decomposition of H 2 O 2 into hydroxyl radicals, which are very reactive. Based on the experiments with the different activated carbon samples, which have similar physical properties, it is proved that the surface chemistry of the catalyst plays a key role, being the basic sample the most active. This is discussed considering the involvement of the free electrons on the graphene basal planes of activated carbon as active centres for the catalytic reaction. Additionally, it is shown that the decolourisation is enhanced at high pH values, and a possible explanation for this observation, based on the proposed mechanism, is given

  5. Involvement of H2O2 in fluazifop-P-butyl-induced cell death in bristly starbur seedlings.

    Science.gov (United States)

    Luo, Xiaoyong; Liu, Zhihang; Sunohara, Yukari; Matsumoto, Hiroshi; Li, Pingliang

    2017-11-01

    In order to understand the action mechanism of fluazifop-P-butyl (FB) in bristly starbur (Acanthospermum hispidum D.C.), a susceptible plant, the role of active oxygen species (ROS) in herbicide-induced cell death in shoots was investigated. FB-induced phytotoxicity was not reduced by the antioxidants, 1,4-diazabicyclooctane (dabaco), sodium azide, l-tryptophan, d-tryptophan, hydroquinone and dimethyl pyridine N-oxide (DMPO). The activities of superoxide dismutase (SOD) and catalase (CAT), in bristly starbur seedlings were significantly increased by FB at 12 HAT and 24 HAT, while ascorbate peroxidase (APX) and glutathione reductase (GR) activities increased only at 12 HAT. The contents of H 2 O 2 in FB-treated bristly starbur seedlings were significantly higher to that of control between 8 and 24 HAT. According to the analysis of potassium iodide - starch or 3,3-diaminobenzidine, the accumulation of hydrogen peroxide was observed in the apical growing point, stem, petiole and veins of FB-treated bristly starbur seedlings at 24 HAT. The cell viability of bristly starbur seedlings treated by 10μM FB decreased at 18 HAT. These results suggested that FB-induced cell death in bristly starbur shoots may be caused by ROS (O 2 - and H 2 O 2 ) generation and lipid peroxidation. Copyright © 2016 Elsevier Inc. All rights reserved.

  6. Preparation of a Superhydrophobic and Peroxidase-like Activity Array Chip for H2O2 Sensing by Surface-Enhanced Raman Scattering.

    Science.gov (United States)

    Yu, Zhi; Park, Yeonju; Chen, Lei; Zhao, Bing; Jung, Young Mee; Cong, Qian

    2015-10-28

    In this paper, we propose a novel and simple method for preparing a dual-biomimetic functional array possessing both superhydrophobic and peroxidase-like activity that can be used for hydrogen peroxide (H2O2) sensing. The proposed method is an integration innovation that combines the above two properties and surface-enhanced Raman scattering (SERS). We integrated a series of well-ordered arrays of Au points (d = 1 mm) onto a superhydrophobic copper (Cu)/silver (Ag) surface by replicating an arrayed molybdenum template. Instead of using photoresists and the traditional lithography method, we utilized a chemical etching method (a substitution reaction between Cu and HAuCl4) with a Cu/Ag superhydrophobic surface as the barrier layer, which has the benefit of water repellency. The as-prepared Au points were observed to possess peroxidase-like activity, allowing for catalytic oxidation of the chromogenic molecule o-phenylenediamine dihydrochloride (OPD). Oxidation was evidenced by a color change in the presence of H2O2, which allows the array chip to act as an H2O2 sensor. In this study, the water repellency of the superhydrophobic surface was used to fabricate the array chip and increase the local reactant concentration during the catalytic reaction. As a result, the catalytic reaction occurred when only 2 μL of an aqueous sample (OPD/H2O2) was placed onto the Au point, and the enzymatic product, 2,3-diaminophenazine, showed a SERS signal distinguishable from that of OPD after mixing with 2 μL of colloidal Au. Using the dual-biomimetic functional array chip, quantitative analysis of H2O2 was performed by observing the change in the SERS spectra, which showed a concentration-dependent behavior for H2O2. This method allows for the detection of H2O2 at concentrations as low as 3 pmol per 2 μL of sample, which is a considerable advantage in H2O2 analysis. The as-prepared substrate was convenient for H2O2 detection because only a small amount of sample was required in

  7. Copper corrosion in irradiated environments. The influence of H2O2 on the electrochemistry of copper dissolution in HC1 electrolyte

    International Nuclear Information System (INIS)

    Smyrl, W.H.; Bell, B.T.; Atanasoski, R.T.; Glass, R.S.

    1987-01-01

    The anodic dissolution of copper has been examined in deaerated, 0.1 M HCl aqueous solution in the presence of H 2 O 2 . Concentrations of H 2 O 2 up to 0.2 M were studied at a rotating copper disk-platinum ring electrode. The open circuit potential (OCP) of copper was found to depend on both peroxide concentration and rotation rate. The OCP shifts towards more positive values with increasing H 2 O 2 concentration (C) and decreasing rotation rate (Omega). The dependence of OCP on (C/Omega/sup 1/2/) was the same as for oxygenated solutions reported earlier [1], at small values of (C/Omega/sup 1/2/). At higher values of (C/Omega/sup 1/2/), departure from the expected behavior was observed. The current-voltage curves for anodic dissolution of copper were also influenced by the presence of peroxide. The curves recorded with the potential scanned in the positive direction showed the expected 60 mV slope, but the reverse scans showed significant departures. At a given potential scan rate, hysteresis was observed which was larger for higher H 2 O 2 concentrations, lower rotation rates, and more positive anodic potential limits. Monitoring the cuprous ions at the outer Pt ring revealed that there was a complex set of events taking place at the copper surface, including film formation and the appearance of cupric ions. 13 references, 7 figures

  8. Copper corrosion in irradiated environments: The influence of H2O2 on the electrochemistry of copper dissolution in HCl electrolyte

    International Nuclear Information System (INIS)

    Smyrl, W.H.; Bell, B.T.; Atanasoski, R.T.; Glass, R.S.

    1986-12-01

    The anodic dissolution of copper was examined in deaerated, 0.1 M HCl aqueous solution in the presence of H 2 O 2 . Concentrations of H 2 O 2 up to 0.2 M were studied at a rotating copper disk-platinum ring electrode. The open circuit potential (OCP) of copper was found to depend on both peroxide concentration and rotation rate. The OCP shifts towards more positive values with increasing H 2 O 2 concentration (C) and decreasing rotation rate. The current-voltage curves for anodic dissolution of copper were also influenced by the presence of peroxide. The curves recorded with the potential scanned in the positive direction showed the expected 60 mV slope, but the reverse scans showed significant departures. At a given potential scan rate, hysteresis was observed which was larger for higher H 2 O 2 concentrations, lower rotation rates, and more positive anodic potential limits. Monitoring the cuprous ions at the outer Pt ring revealed that there was a complex set of events taking place at the copper surface, including film formation and the appearance of cupric ions. 13 refs., 7 figs

  9. Oxidative damage to fibronectin. 2. The effect of H2O2 and the hydroxyl radical

    International Nuclear Information System (INIS)

    Vissers, M.C.; Winterbourn, C.C.

    1991-01-01

    The effect of H2O2 and the hydroxyl radical (.OH) on fibronectin was investigated. .OH was generated in three ways: (1) by radiolysis with 60Co under N2O, or by the Fenton system using either (2) equimolar Fe(2+)-EDTA and H2O2 or (3) H2O2 and catalytic amounts of Fe(2+)-EDTA recycled with ascorbate. Each system had a different effect. H2O2 alone caused no changes, even at an 800-fold molar excess. Radiolytic .OH caused a rapid loss of tryptophan fluorescence, an increase in bityrosine fluorescence, and extensive crosslinking. The Fenton system using Fe-EDTA, H2O2, and ascorbate caused a loss in tryptophan fluorescence, a smaller increase in bityrosine than was seen with radiolytic .OH, and a threefold increase in carbonyl groups. On sodium dodecyl sulfate-polyacrylamide gel electrophoresis fragmentation of fibronectin was seen. In contrast, when .OH was generated with equimolar Fe-EDTA and H2O2, the only change was a small increase in bityrosine fluorescence at the highest dose of oxidant. None of the systems used affected cysteine. All the changes except the loss of tryptophan by radiolytic .OH were completely inhibited with mannitol. The differences seen with radiolytic .OH and the Fe-EDTA, H2O2, ascorbate system were not solely due to O2 in the latter system since similar results were obtained under N2. The differences between radiolytic .OH and the Fenton systems could be partly due to the components of the latter systems reacting with .OH and thus competing with fibronectin. The authors results demonstrate that the extent and type of fibronectin damage by .OH is dependent on the mode of radical generation

  10. Sources of superoxide/H2O2 during mitochondrial proline oxidation

    Directory of Open Access Journals (Sweden)

    Renata L.S. Goncalves

    2014-01-01

    Full Text Available p53 Inducible gene 6 (PIG6 encodes mitochondrial proline dehydrogenase (PRODH and is up-regulated several fold upon p53 activation. Proline dehydrogenase is proposed to generate radicals that contribute to cancer cell apoptosis. However, there are at least 10 mitochondrial sites that can produce superoxide and/or H2O2, and it is unclear whether proline dehydrogenase generates these species directly, or instead drives production by other sites. Amongst six cancer cell lines, ZR75-30 human breast cancer cells had the highest basal proline dehydrogenase levels, and mitochondria isolated from ZR75-30 cells consumed oxygen and produced H2O2 with proline as sole substrate. Insects use proline oxidation to fuel flight, and mitochondria isolated from Drosophila melanogaster were even more active with proline as sole substrate than ZR75-30 mitochondria. Using mitochondria from these two models we identified the sites involved in formation of superoxide/H2O2 during proline oxidation. In mitochondria from Drosophila the main sites were respiratory complexes I and II. In mitochondria from ZR75-30 breast cancer cells the main sites were complex I and the oxoglutarate dehydrogenase complex. Even with combinations of substrates and respiratory chain inhibitors designed to minimize the contributions of other sites and maximize any superoxide/H2O2 production from proline dehydrogenase itself, there was no significant direct contribution of proline dehydrogenase to the observed H2O2 production. Thus proline oxidation by proline dehydrogenase drives superoxide/H2O2 production, but it does so mainly or exclusively by providing anaplerotic carbon for other mitochondrial dehydrogenases and not by producing superoxide/H2O2 directly.

  11. The H2O2 scavenger ebselen decreases ethanol-induced locomotor stimulation in mice.

    Science.gov (United States)

    Ledesma, Juan Carlos; Font, Laura; Aragon, Carlos M G

    2012-07-01

    In the brain, the enzyme catalase by reacting with H(2)O(2) forms Compound I (catalase-H(2)O(2) system), which is the main system of central ethanol metabolism to acetaldehyde. Previous research has demonstrated that acetaldehyde derived from central-ethanol metabolism mediates some of the psychopharmacological effects produced by ethanol. Manipulations that modulate central catalase activity or sequester acetaldehyde after ethanol administration modify the stimulant effects induced by ethanol in mice. However, the role of H(2)O(2) in the behavioral effects caused by ethanol has not been clearly addressed. The present study investigated the effects of ebselen, an H(2)O(2) scavenger, on ethanol-induced locomotion. Swiss RjOrl mice were pre-treated with ebselen (0-50mg/kg) intraperitoneally (IP) prior to administration of ethanol (0-3.75g/kg; IP). In another experiment, animals were pre-treated with ebselen (0 or 25mg/kg; IP) before caffeine (15mg/kg; IP), amphetamine (2mg/kg; IP) or cocaine (10mg/kg; IP) administration. Following these treatments, animals were placed in an open field to measure their locomotor activity. Additionally, we evaluated the effect of ebselen on the H(2)O(2)-mediated inactivation of brain catalase activity by 3-amino-1,2,4-triazole (AT). Ebselen selectively prevented ethanol-induced locomotor stimulation without altering the baseline activity or the locomotor stimulating effects caused by caffeine, amphetamine and cocaine. Ebselen reduced the ability of AT to inhibit brain catalase activity. Taken together, these data suggest that a decline in H(2)O(2) levels might result in a reduction of the ethanol locomotor-stimulating effects, indicating a possible role for H(2)O(2) in some of the psychopharmacological effects produced by ethanol. Copyright © 2011 Elsevier Ireland Ltd. All rights reserved.

  12. MicroR828 regulates lignin and H2O2 accumulation in sweet potato on wounding.

    Science.gov (United States)

    Lin, Jeng-Shane; Lin, Chih-Ching; Lin, Hsin-Hung; Chen, Yu-Chi; Jeng, Shih-Tong

    2012-10-01

    MicroRNAs (miRNAs) are small noncoding RNAs which post-transcriptionally regulate gene expression by directing mRNA cleavage or translational inhibition. miRNAs play multiple roles in the growth, development and stress responses in plants. However, little is known of the wounding-responsive miRNAs and their regulation. Here, we investigated the expression patterns of microR828 (miR828) on wounding in sweet potato (Ipomoea batatas cv Tainung 57). The expression of miR828 was only detected in leaves, and was induced by wounding rather than by ethylene, hydrogen peroxide (H2O2), methyl jasmonate or nitric oxide (NO). Moreover, cyclic guanosine monophosphate (cGMP) was necessary for miR828 accumulation in leaves on wounding. Two miR828 target candidates, named IbMYB and IbTLD, were obtained by cDNA cloning, and their mRNA cleavage caused by miR828 was confirmed by cleavage site mapping, agro-infiltration and transgenics studies. The reduction in IbMYB and IbTLD expression coincided with the induction of miR828, demonstrating that IbMYB and IbTLD might be miR828 targets. Furthermore, transgenic sweet potato overexpressing miR828 precursor affected lignin and H2O2 contents. These results showed that cGMP could regulate wounding-responsive miR828, which repressed the expression of IbMYB and IbTLD. Subsequently, lignin and H2O2 were accumulated to participate in defense mechanisms. © 2012 The Authors. New Phytologist © 2012 New Phytologist Trust.

  13. Degradação fotoquímica e reuso da água obtida de um efluente têxtil tratado via UV/H2O2

    Directory of Open Access Journals (Sweden)

    Jorge Marcos Rosa

    2010-01-01

    Full Text Available This work aimed to the degradation by photochemistry process and reuse of the water from textile effluent. The pH effect on the degradation of reactive black 5 dye was studied at pH 7, 9 and 11, catalyzed by hydrogen peroxide (H2O2 on ultra-violet (UV irradiation. After the treatment, all conversion obtained was up to a = 0.96, on the dye degradation at ¿máx = 580 nm for anyone pH used. The treated waters from textile effluents were reused in dyeing of one fabric as some color and its fabric was compared a standard of dyeing using bi-filtered water. It was observed and confirmed from results observed by spectrophotometers and color deviation (minor than 1.0 that the textile effluent with RB5 dye treated by H2O2/UV at pH 7, 9, and 11 can be used in new dyeing.

  14. Lessons Learned (3 Years of H2O2 Propulsion System Testing Efforts at NASA's John C. Stennis Space Center)

    Science.gov (United States)

    Taylor, Gary O.

    2001-01-01

    John C. Stennis Space Center continues to support the Propulsion community in an effort to validate High-Test Peroxide as an alternative to existing/future oxidizers. This continued volume of peroxide test/handling activity at Stennis Space Center (SSC) provides numerous opportunities for the SSC team to build upon previously documented 'lessons learned'. SSC shall continue to strive to document their experience and findings as H2O2 issues surface. This paper is intended to capture all significant peroxide issues that we have learned over the last three years. This data (lessons learned) has been formulated from practical handling, usage, storage, operations, and initial development/design of our systems/facility viewpoint. The paper is intended to be an information type tool and limited in technical rational; therefore, presenting the peroxide community with some issues to think about as the continued interest in peroxide evolves and more facilities/hardware are built. These lessons learned are intended to assist industry in mitigating problems and identifying potential pitfalls when dealing with the requirements for handling high-test peroxide.

  15. Transgenic Centipedegrass (Eremochloa ophiuroides [Munro] Hack. Overexpressing S-Adenosylmethionine Decarboxylase (SAMDC Gene for Improved Cold Tolerance Through Involvement of H2O2 and NO Signaling

    Directory of Open Access Journals (Sweden)

    Jianhao Luo

    2017-09-01

    Full Text Available Centipedegrass (Eremochloa ophiuroides [Munro] Hack. is an important warm-season turfgrass species. Transgenic centipedgrass plants overexpressing S-adenosylmethionine decarboxylase from bermudagrass (CdSAMDC1 that was induced in response to cold were generated in this study. Higher levels of CdSAMDC1 transcript and sperimidine (Spd and spermin (Spm concentrations and enhanced freezing and chilling tolerance were observed in transgenic plants as compared with the wild type (WT. Transgenic plants had higher levels of polyamine oxidase (PAO activity and H2O2 than WT, which were blocked by pretreatment with methylglyoxal bis (guanylhydrazone or MGBG, inhibitor of SAMDC, indicating that the increased PAO and H2O2 were a result of expression of CdSAMDC1. In addition, transgenic plants had higher levels of nitrate reductase (NR activity and nitric oxide (NO concentration. The increased NR activity were blocked by pretreatment with MGBG and ascorbic acid (AsA, scavenger of H2O2, while the increased NO level was blocked by MGBG, AsA, and inhibitors of NR, indicating that the enhanced NR-derived NO was dependent upon H2O2, as a result of expression CdSAMDC1. Elevated superoxide dismutase (SOD and catalase (CAT activities were observed in transgenic plants than in WT, which were blocked by pretreatment with MGBG, AsA, inhibitors of NR and scavenger of NO, indicating that the increased activities of SOD and CAT depends on expression of CdSAMDC1, H2O2, and NR-derived NO. Our results suggest that the elevated cold tolerance was associated with PAO catalyzed production of H2O2, which in turn led to NR-derived NO production and induced antioxidant enzyme activities in transgenic plants.

  16. Transgenic Centipedegrass (Eremochloa ophiuroides [Munro] Hack.) Overexpressing S-Adenosylmethionine Decarboxylase (SAMDC) Gene for Improved Cold Tolerance Through Involvement of H2O2 and NO Signaling.

    Science.gov (United States)

    Luo, Jianhao; Liu, Mingxi; Zhang, Chendong; Zhang, Peipei; Chen, Jingjing; Guo, Zhenfei; Lu, Shaoyun

    2017-01-01

    Centipedegrass ( Eremochloa ophiuroides [Munro] Hack.) is an important warm-season turfgrass species. Transgenic centipedgrass plants overexpressing S-adenosylmethionine decarboxylase from bermudagrass ( CdSAMDC1 ) that was induced in response to cold were generated in this study. Higher levels of CdSAMDC1 transcript and sperimidine (Spd) and spermin (Spm) concentrations and enhanced freezing and chilling tolerance were observed in transgenic plants as compared with the wild type (WT). Transgenic plants had higher levels of polyamine oxidase (PAO) activity and H 2 O 2 than WT, which were blocked by pretreatment with methylglyoxal bis (guanylhydrazone) or MGBG, inhibitor of SAMDC, indicating that the increased PAO and H 2 O 2 were a result of expression of CdSAMDC1 . In addition, transgenic plants had higher levels of nitrate reductase (NR) activity and nitric oxide (NO) concentration. The increased NR activity were blocked by pretreatment with MGBG and ascorbic acid (AsA), scavenger of H 2 O 2 , while the increased NO level was blocked by MGBG, AsA, and inhibitors of NR, indicating that the enhanced NR-derived NO was dependent upon H 2 O 2 , as a result of expression CdSAMDC1 . Elevated superoxide dismutase (SOD) and catalase (CAT) activities were observed in transgenic plants than in WT, which were blocked by pretreatment with MGBG, AsA, inhibitors of NR and scavenger of NO, indicating that the increased activities of SOD and CAT depends on expression of CdSAMDC1 , H 2 O 2 , and NR-derived NO. Our results suggest that the elevated cold tolerance was associated with PAO catalyzed production of H 2 O 2 , which in turn led to NR-derived NO production and induced antioxidant enzyme activities in transgenic plants.

  17. H2O2 recycling during oxidation of the arylglycerol beta-aryl ether lignin structure by lignin peroxidase and glyoxal oxidase.

    Science.gov (United States)

    Hammel, K E; Mozuch, M D; Jensen, K A; Kersten, P J

    1994-11-15

    Oxidative C alpha-C beta cleavage of the arylglycerol beta-aryl ether lignin model 1-(3,4-dimethoxy-phenyl)-2-phenoxypropane-1,3-diol (I) by Phanerochaete chrysosporium lignin peroxidase in the presence of limiting H2O2 was enhanced 4-5-fold by glyoxal oxidase from the same fungus. Further investigation showed that each C alpha-C beta cleavage reaction released 0.8-0.9 equiv of glycolaldehyde, a glyoxal oxidase substrate. The identification of glycolaldehyde was based on 13C NMR spectrometry of reaction product obtained from beta-, gamma-, and beta,gamma-13C-substituted I, and quantitation was based on an enzymatic NADH-linked assay. The oxidation of glycolaldehyde by glyoxal oxidase yielded 0.9 oxalate and 2.8 H2O2 per reaction, as shown by quantitation of oxalate as 2,3-dihydroxyquinoxaline after derivatization with 1,2-diaminobenzene and by quantitation of H2O2 in coupled spectrophotometric assays with veratryl alcohol and lignin peroxidase. These results suggest that the C alpha-C beta cleavage of I by lignin peroxidase in the presence of glyoxal oxidase should regenerate as many as 3 H2O2. Calculations based on the observed enhancement of LiP-catalyzed C alpha-C beta cleavage by glyoxal oxidase showed that approximately 2 H2O2 were actually regenerated per cleavage of I when both enzymes were present. The cleavage of arylglycerol beta-aryl ether structures by ligninolytic enzymes thus recycles H2O2 to support subsequent cleavage reactions.

  18. Oxidative desulfurization of dibenzothiophene with hydrogen peroxide catalyzed by selenium(IV)-containing peroxotungstate.

    Science.gov (United States)

    Hu, Yiwen; He, Qihui; Zhang, Zheng; Ding, Naidong; Hu, Baixing

    2011-11-28

    With stoichiometric H(2)O(2) as oxidant, dibenzothiophene (DBT) is oxidized to its corresponding sulfone with high efficiency, catalyzed by a sub-valence heteronuclear peroxotungstate, [C(18)H(37)N(CH(3))(3)](4)[H(2)Se(IV)(3)W(6)O(34)], under mild biphase conditions and the catalyst shows remarkable selectivity of catalytic oxidation towards DBT, cinnamyl alcohol and quinoline.

  19. Multiple myeloma cells’ capacity to decompose H2O2 determines lenalidomide sensitivity

    Science.gov (United States)

    Sebastian, Sinto; Zhu, Yuan X.; Braggio, Esteban; Shi, Chang-Xin; Panchabhai, Sonali C.; Van Wier, Scott A.; Ahmann, Greg J.; Chesi, Marta; Bergsagel, P. Leif; Stewart, A. Keith

    2017-01-01

    Lenalidomide is an immunomodulatory drug (IMiDs) with clinical efficacy in multiple myeloma (MM) and other late B-cell neoplasms. Although cereblon (CRBN) is an essential requirement for IMiD action, the complete molecular and biochemical mechanisms responsible for lenalidomide-mediated sensitivity or resistance remain unknown. Here, we report that IMiDs work primarily via inhibition of peroxidase-mediated intracellular H2O2 decomposition in MM cells. MM cells with lower H2O2-decomposition capacity were more vulnerable to lenalidomide-induced H2O2 accumulation and associated cytotoxicity. CRBN-dependent degradation of IKZF1 and IKZF3 was a consequence of H2O2-mediated oxidative stress. Lenalidomide increased intracellular H2O2 levels by inhibiting thioredoxin reductase (TrxR) in cells expressing CRBN, causing accumulation of immunoglobulin light-chain dimers, significantly increasing endoplasmic reticulum stress and inducing cytotoxicity by activation of BH3-only protein Bim in MM. Other direct inhibitors of TrxR and thioredoxin (Trx) caused similar cytotoxicity, but in a CRBN-independent fashion. Our findings could help identify patients most likely to benefit from IMiDs and suggest direct TrxR or Trx inhibitors for MM therapy. PMID:28028022

  20. Differentiating between apparent and actual rates of H2O2 metabolism by isolated rat muscle mitochondria to test a simple model of mitochondria as regulators of H2O2 concentration

    Science.gov (United States)

    Treberg, Jason R.; Munro, Daniel; Banh, Sheena; Zacharias, Pamela; Sotiri, Emianka

    2015-01-01

    Mitochondria are often regarded as a major source of reactive oxygen species (ROS) in animal cells, with H2O2 being the predominant ROS released from mitochondria; however, it has been recently demonstrated that energized brain mitochondria may act as stabilizers of H2O2 concentration (Starkov et al. [1]) based on the balance between production and the consumption of H2O2, the later of which is a function of [H2O2] and follows first order kinetics. Here we test the hypothesis that isolated skeletal muscle mitochondria, from the rat, are able to modulate [H2O2] based upon the interaction between the production of ROS, as superoxide/H2O2, and the H2O2 decomposition capacity. The compartmentalization of detection systems for H2O2 and the intramitochondrial metabolism of H2O2 leads to spacial separation between these two components of the assay system. This results in an underestimation of rates when relying solely on extramitochondrial H2O2 detection. We find that differentiating between these apparent rates found when using extramitochondrial H2O2 detection and the actual rates of metabolism is important to determining the rate constant for H2O2 consumption by mitochondria in kinetic experiments. Using the high rate of ROS production by mitochondria respiring on succinate, we demonstrate that net H2O2 metabolism by mitochondria can approach a stable steady-state of extramitochondrial [H2O2]. Importantly, the rate constant determined by extrapolation of kinetic experiments is similar to the rate constant determined as the [H2O2] approaches a steady state. PMID:26001520

  1. Anion- or Cation-Exchange Membranes for NaBH4/H2O2 Fuel Cells?

    Science.gov (United States)

    Sljukić, Biljana; Morais, Ana L; Santos, Diogo M F; Sequeira, César A C

    2012-07-19

    Direct borohydride fuel cells (DBFC), which operate on sodium borohydride (NaBH4) as the fuel, and hydrogen peroxide (H2O2) as the oxidant, are receiving increasing attention. This is due to their promising use as power sources for space and underwater applications, where air is not available and gas storage poses obvious problems. One key factor to improve the performance of DBFCs concerns the type of separator used. Both anion- and cation-exchange membranes may be considered as potential separators for DBFC. In the present paper, the effect of the membrane type on the performance of laboratory NaBH4/H2O2 fuel cells using Pt electrodes is studied at room temperature. Two commercial ion-exchange membranes from Membranes International Inc., an anion-exchange membrane (AMI-7001S) and a cation-exchange membrane (CMI-7000S), are tested as ionic separators for the DBFC. The membranes are compared directly by the observation and analysis of the corresponding DBFC's performance. Cell polarization, power density, stability, and durability tests are used in the membranes' evaluation. Energy densities and specific capacities are estimated. Most tests conducted, clearly indicate a superior performance of the cation-exchange membranes over the anion-exchange membrane. The two membranes are also compared with several other previously tested commercial membranes. For long term cell operation, these membranes seem to outperform the stability of the benchmark Nafion membranes but further studies are still required to improve their instantaneous power load.

  2. NADPH oxidase-derived H2O2 subverts pathogen signaling by oxidative phosphotyrosine conversion to PB-DOPA

    Science.gov (United States)

    Alvarez, Luis A.; Kovačič, Lidija; Rodríguez, Javier; Gosemann, Jan-Hendrik; Kubica, Malgorzata; Pircalabioru, Gratiela G.; Friedmacher, Florian; Cean, Ada; Ghişe, Alina; Sărăndan, Mihai B.; Puri, Prem; Daff, Simon; Plettner, Erika; von Kriegsheim, Alex; Bourke, Billy; Knaus, Ulla G.

    2016-01-01

    Strengthening the host immune system to fully exploit its potential as antimicrobial defense is vital in countering antibiotic resistance. Chemical compounds released during bidirectional host–pathogen cross-talk, which follows a sensing-response paradigm, can serve as protective mediators. A potent, diffusible messenger is hydrogen peroxide (H2O2), but its consequences on extracellular pathogens are unknown. Here we show that H2O2, released by the host on pathogen contact, subverts the tyrosine signaling network of a number of bacteria accustomed to low-oxygen environments. This defense mechanism uses heme-containing bacterial enzymes with peroxidase-like activity to facilitate phosphotyrosine (p-Tyr) oxidation. An intrabacterial reaction converts p-Tyr to protein-bound dopa (PB-DOPA) via a tyrosinyl radical intermediate, thereby altering antioxidant defense and inactivating enzymes involved in polysaccharide biosynthesis and metabolism. Disruption of bacterial signaling by DOPA modification reveals an infection containment strategy that weakens bacterial fitness and could be a blueprint for antivirulence approaches. PMID:27562167

  3. NADPH oxidase-derived H2O2 subverts pathogen signaling by oxidative phosphotyrosine conversion to PB-DOPA.

    Science.gov (United States)

    Alvarez, Luis A; Kovačič, Lidija; Rodríguez, Javier; Gosemann, Jan-Hendrik; Kubica, Malgorzata; Pircalabioru, Gratiela G; Friedmacher, Florian; Cean, Ada; Ghişe, Alina; Sărăndan, Mihai B; Puri, Prem; Daff, Simon; Plettner, Erika; von Kriegsheim, Alex; Bourke, Billy; Knaus, Ulla G

    2016-09-13

    Strengthening the host immune system to fully exploit its potential as antimicrobial defense is vital in countering antibiotic resistance. Chemical compounds released during bidirectional host-pathogen cross-talk, which follows a sensing-response paradigm, can serve as protective mediators. A potent, diffusible messenger is hydrogen peroxide (H2O2), but its consequences on extracellular pathogens are unknown. Here we show that H2O2, released by the host on pathogen contact, subverts the tyrosine signaling network of a number of bacteria accustomed to low-oxygen environments. This defense mechanism uses heme-containing bacterial enzymes with peroxidase-like activity to facilitate phosphotyrosine (p-Tyr) oxidation. An intrabacterial reaction converts p-Tyr to protein-bound dopa (PB-DOPA) via a tyrosinyl radical intermediate, thereby altering antioxidant defense and inactivating enzymes involved in polysaccharide biosynthesis and metabolism. Disruption of bacterial signaling by DOPA modification reveals an infection containment strategy that weakens bacterial fitness and could be a blueprint for antivirulence approaches.

  4. Light-assisted decomposition of dyes over iron-bearing soil clays in the presence of H2O2

    International Nuclear Information System (INIS)

    Wang Zhaohui; Ma Wanhong; Chen Chuncheng; Zhao Jincai

    2009-01-01

    Four types of soil clays from different sites in China have been chosen to simulate chemical remediation of soils contaminated with dyes by light-assisted Fenton-like method. X-Ray diffraction (XRD), X-ray photoelectron spectroscopic (XPS) and electron spin resonance (ESR) measurements indicated that these soil clays contain iron oxides such as magnetite and hematite, where nondistorted iron active sites (ESR spectra, g = 2.3) predominate. Upon visible or UV irradiation, the soil clays were very effective for the degradation of nonbiodegradable cationic dyes such as Rhodamine B (RhB) by activating H 2 O 2 at neutral pH. The photodegradation rates of RhB were closely related to total Fe content in clays and H 2 O 2 dosage, indicating the mineral-catalyzed Fenton-like reactions operated. Soil organic matters (SOM) would remarkably inhibit the photodecomposition of RhB dye. The reaction products were some low-molecular-weight dicarboxylic acids and their derivatives, all of which are easily biodegradable. A possible mechanism was proposed based on the results obtained by spin-trapping ESR technique.

  5. Beneficiation of titanium concentrate (anatase) by HCl/H2O2 leaching of impurities

    International Nuclear Information System (INIS)

    Trindade, R.B.E.; Teixeira, L.A.C.

    1988-01-01

    The HCl/H 2 O 2 leaching of impurities from a Brazilian anatase (TiO 2 ) concentrate has been investigated by factorial experimentations. The effects of the following variables were investigated: temperature (50-90 0 C), redox potential (with and without oxidizing agent-H 2 O 2 ) and HCl concentration (4-18,5%). The conclusions were based on the analyses of Fe, Ca, P, Al, Si, Th,Ce, La, U and Ti in the beneficiated concentrates. The final results recommended the following optimum operational conditions, in a four stage countercurrent leaching: in the 4 th reactor (discharge of beneficiated concentrate): HCl fed at 18.5%, T=75 0 C, and addition of H 2 O 2 at a potential (eH) of 850 mV; in the first three reactors: T=90 0 C; with no oxidizing agent. (author) [pt

  6. Treatment of hospital laundry wastewater by UV/H2O2 process.

    Science.gov (United States)

    Zotesso, Jaqueline Pirão; Cossich, Eneida Sala; Janeiro, Vanderly; Tavares, Célia Regina Granhen

    2017-03-01

    Hospitals consume a large volume of water to carry out their activities and, hence, generate a large volume of effluent that is commonly discharged into the local sewage system without any treatment. Among the various sectors of healthcare facilities, the laundry is responsible for the majority of water consumption and generates a highly complex effluent. Although several advanced oxidation processes (AOPs) are currently under investigation on the degradation of a variety of contaminants, few of them are based on real wastewater samples. In this paper, the UV/H 2 O 2 AOP was evaluated on the treatment of a hospital laundry wastewater, after the application of a physicochemical pretreatment composed of coagulation-flocculation and anthracite filtration. For the UV/H 2 O 2 process, a photoreactor equipped with a low-pressure UV-C lamp was used and the effects of initial pH and [H 2 O 2 ]/chemical oxygen demand (COD) ratio on COD removal were investigated through a randomized factorial block design that considered the batches of effluent as blocks. The results indicated that the initial pH had no significant effect on the COD removal, and the process was favored by the increase in [H 2 O 2 ]/COD ratio. Color and turbidity were satisfactorily reduced after the application of the physicochemical pretreatment, and COD was completely removed by the UV/H 2 O 2 process under suitable conditions. The results of this study show that the UV/H 2 O 2 AOP is a promising candidate for hospital laundry wastewater treatment and should be explored to enable wastewater reuse in the washing process.

  7. Antioxidant ameliorating effects against H2O2-induced cytotoxicity in primary endometrial cells.

    Science.gov (United States)

    Zal, F; Khademi, F; Taheri, R; Mostafavi-Pour, Z

    2018-02-01

    Oxidative stress and a disrupted antioxidant system are involved in a variety of pregnancy complications. In the present study, the role of vitamin E (Vit E) and folate as radical scavengers on the GSH homeostasis in stress oxidative induced in rat endometrial cells was investigated. Primary endometrial stromal cell cultures treated with 50 and 200 µM of H 2 O 2 and evaluated the cytoprotective effects of Vit E (5 µM) and folate (0.01 µM) in H 2 O 2 -treated cells for 24 h. Following the exposure of endometrial cells to H 2 O 2 alone and in the presence of Vit E and/or folate, cell survival, glutathione peroxidase (GPx) and glutathione reductase activities and the level of reduced glutathione (GSH) were measured. Cell adhesions comprise of cell attachment and spreading on collagen were determined. Flow cytometric analysis using annexin V was used to measure apoptosis. H 2 O 2 treatment showed a marked decrease in cell viability, GPx and GR activities and the level of GSH. Although Vit E or folate had some protective effect, combination therapy with Vit E and folate attenuated all the changes due to H 2 O 2 toxicity. An increasing number of alive cells was showed in the cells exposed to H 2 O 2 (50 µM) accompanied by co-treatment with Vit E and folic acid. The present findings indicate that co-administration of Vit E and folate before and during pregnancy may maintain a viable pregnancy and contribute to its clinical efficacy for the treatment of some idiopathic infertility.

  8. Photodegradation and toxicity changes of antibiotics in UV and UV/H2O2 process

    International Nuclear Information System (INIS)

    Yuan Fang; Hu Chun; Hu Xuexiang; Wei Dongbin; Chen Yong; Qu Jiuhui

    2011-01-01

    The photodegradation of three antibiotics, oxytetracycline (OTC), doxycycline (DTC), and ciprofloxacin (CIP) in UV and UV/H 2 O 2 process was investigated with a low-pressure UV lamp system. Experiments were performed in buffered ultrapure water (UW), local surface water (SW), and treated water from local municipal drinking water treatment plant (DW) and wastewater treatment plant (WW). The efficiency of UV/H 2 O 2 process was affected by water quality. For all of the three selected antibiotics, the fastest degradation was observed in DW, and the slowest degradation occurred in WW. This phenomenon can be explained by R OH,UV , defined as the experimentally determined ·OH radical exposure per UV fluence. The R OH,UV values represent the background ·OH radical scavenging in water matrix, obtained by the degradation of para-chlorobenzoic acid (pCBA), a probe compound. In natural water, the indirect degradation of CIP did not significantly increase with the addition of H 2 O 2 due to its effective degradation by UV direct photolysis. Moreover, the formation of several photoproducts and oxidation products of antibiotics in UV/H 2 O 2 process was identified using GC-MS. Toxicity assessed by Vibrio fischer (V. fischer), was increased in UV photolysis, for the photoproducts still preserving the characteristic structure of the parent compounds. While in UV/H 2 O 2 process, toxicity increased first, and then decreased; nontoxic products were formed by the oxidation of ·OH radical. In this process, detoxification was much easier than mineralization for the tested antibiotics, and the optimal time for the degradation of pollutants in UV/H 2 O 2 process would be determined by parent compound degradation and toxicity changes.

  9. Mitochondrial H2O2 signaling is controlled by the concerted action of peroxiredoxin III and sulfiredoxin: Linking mitochondrial function to circadian rhythm.

    Science.gov (United States)

    Rhee, Sue Goo; Kil, In Sup

    2016-11-01

    Mitochondria produce hydrogen peroxide (H 2 O 2 ) during energy metabolism in most mammalian cells as well as during the oxidation of cholesterol associated with the synthesis of steroid hormones in steroidogenic cells. Some of the H 2 O 2 produced in mitochondria is released into the cytosol, where it serves as a key regulator of various signaling pathways. Given that mitochondria are equipped with several H 2 O 2 -eliminating enzymes, however, it had not been clear how mitochondrial H 2 O 2 can escape destruction by these enzymes for such release. Peroxiredoxin III (PrxIII) is the most abundant and efficient H 2 O 2 -eliminating enzyme in mitochondria of most cell types. We found that PrxIII undergoes reversible inactivation through hyperoxidation of its catalytic cysteine residue to cysteine sulfinic acid, and that release of mitochondrial H 2 O 2 likely occurs as a result of such PrxIII inactivation. The hyperoxidized form of PrxIII (PrxIII-SO 2 H) is reduced and reactivated by sulfiredoxin (Srx). We also found that the amounts of PrxIII-SO 2 H and Srx undergo antiphasic circadian oscillation in mitochondria of the adrenal gland, heart, and brown adipose tissue of mice maintained under normal conditions. Cytosolic Srx was found to be imported into mitochondria via a mechanism that requires formation of a disulfide-linked complex with heat shock protein 90, which is likely promoted by H 2 O 2 released from mitochondria. The imported Srx was found to be degraded by Lon protease in a manner dependent on PrxIII hyperoxidation state. The coordinated import and degradation of Srx underlie Srx oscillation and consequent PrxIII-SO 2 H oscillation in mitochondria. The rhythmic change in the amount of PrxIII-SO 2 H suggests that mitochondrial release of H 2 O 2 is also likely a circadian event that conveys temporal information on steroidogenesis in the adrenal gland and on energy metabolism in heart and brown adipose tissue to cytosolic signaling pathways. Copyright

  10. Garlic and H2O2 in overcoming dormancy on the vine “Cabernet Sauvignon”

    OpenAIRE

    Saavedra del Aguila Juan; Pereira Dachi Ângela; Nogueira Fernandes Elizeu; Lais Hamm Bruna; Corrêa de Almeida Fabiane; Moreira Silveira Jansen

    2015-01-01

    The objective of this experiment was to evaluate the effect of garlic extract, H2O2 and hydrogen cyanamide on dormancy break, budding and maturation of “Cabernet Sauvignon” in the Campaign Region – Brazil. In late winter 2014 and after drought pruning were performed spraying in the bud: T1 – distilled water (control); T2 – 3.0% of hydrogen cyanamide; T3 – 18.0% H2O2; and T4 – 3.0% garlic extract. It was evaluated in the field: the number of sprouted buds per plant, number of bunches per plant...

  11. Effect of plant extracts on H2O2-induced inflammatory gene expression in macrophages

    Science.gov (United States)

    Pomari, Elena; Stefanon, Bruno; Colitti, Monica

    2014-01-01

    Background Arctium lappa (AL), Camellia sinensis (CS), Echinacea angustifolia, Eleutherococcus senticosus, Panax ginseng (PG), and Vaccinium myrtillus (VM) are plants traditionally used in many herbal formulations for the treatment of various conditions. Although they are well known and already studied for their anti-inflammatory properties, their effects on H2O2-stimulated macrophages are a novel area of study. Materials and methods Cell viability was tested after treatment with increasing doses of H2O2 and/or plant extracts at different times of incubation to identify the optimal experimental conditions. The messenger (m)RNA expression of TNFα, COX2, IL1β, NFκB1, NFκB2, NOS2, NFE2L2, and PPARγ was analyzed in macrophages under H2O2 stimulation. The same genes were also quantified after plant extract treatment on cells pre-stimulated with H2O2. Results A noncytotoxic dose (200 μM) of H2O2 induced active mRNA expression of COX2, IL1β, NFE2L2, NFκB1, NFκB2, NOS2, and TNFα, while PPARγ was depressed. The expression of all genes tested was significantly (P<0.001) regulated by plant extracts after pre-stimulation with H2O2. COX2 was downregulated by AL, PG, and VM. All extracts depressed IL1β expression, but upregulated NFE2L2. NFκB1, NFκB2, and TNFα were downregulated by AL, CS, PG, and VM. NOS2 was inhibited by CS, PG, and VM. PPARγ was decreased only after treatment with E. angustifolia and E. senticosus. Conclusion The results of the present study indicate that the stimulation of H2O2 on RAW267.4 cells induced the transcription of proinflammatory mediators, showing that this could be an applicable system by which to activate macrophages. Plant extracts from AL, CS, PG, and VM possess in vitro anti-inflammatory activity on H2O2-stimulated macrophages by modulating key inflammation mediators. Further in vitro and in vivo investigation into molecular mechanisms modulated by herbal extracts should be undertaken to shed light on the development of novel

  12. Effect of plant extracts on H2O2-induced inflammatory gene expression in macrophages

    Directory of Open Access Journals (Sweden)

    Pomari E

    2014-06-01

    Full Text Available Elena Pomari, Bruno Stefanon, Monica Colitti Department of Agricultural and Environmental Sciences, University of Udine, Udine, Italy Background: Arctium lappa (AL, Camellia sinensis (CS, Echinacea angustifolia, Eleutherococcus senticosus, Panax ginseng (PG, and Vaccinium myrtillus (VM are plants traditionally used in many herbal formulations for the treatment of various conditions. Although they are well known and already studied for their anti-inflammatory properties, their effects on H2O2-stimulated macrophages are a novel area of study. Materials and methods: Cell viability was tested after treatment with increasing doses of H2O2 and/or plant extracts at different times of incubation to identify the optimal experimental conditions. The messenger (mRNA expression of TNFα, COX2, IL1β, NFκB1, NFκB2, NOS2, NFE2L2, and PPARγ was analyzed in macrophages under H2O2 stimulation. The same genes were also quantified after plant extract treatment on cells pre-stimulated with H2O2. Results: A noncytotoxic dose (200 µM of H2O2 induced active mRNA expression of COX2, IL1β, NFE2L2, NFκB1, NFκB2, NOS2, and TNFα, while PPARγ was depressed. The expression of all genes tested was significantly (P<0.001 regulated by plant extracts after pre-stimulation with H2O2. COX2 was downregulated by AL, PG, and VM. All extracts depressed IL1β expression, but upregulated NFE2L2. NFκB1, NFκB2, and TNFα were downregulated by AL, CS, PG, and VM. NOS2 was inhibited by CS, PG, and VM. PPARγ was decreased only after treatment with E. angustifolia and E. senticosus. Conclusion: The results of the present study indicate that the stimulation of H2O2 on RAW267.4 cells induced the transcription of proinflammatory mediators, showing that this could be an applicable system by which to activate macrophages. Plant extracts from AL, CS, PG, and VM possess in vitro anti-inflammatory activity on H2O2-stimulated macrophages by modulating key inflammation mediators. Further in

  13. Ammonia removal from leachate by photochemical process using H2O2

    Directory of Open Access Journals (Sweden)

    Giovani Archanjo Brota

    2010-08-01

    Full Text Available In this work, it was studied the optimization of the photochemical process using H2O2/UV in order to reduce the concentration of ammonia in leachate. It was used landfills leachate previously treated in the development of studies. A photochemical reactor with the capacity of 1.7 liters equipped with refrigeration system and recirculation of leachate was employed in the research. The influence of temperature, the light bulb power, the concentration of H2O2 and treatment time were tested during the study. A removal of 97% of ammonia was observed at 90 min.

  14. Diatomite as high performance and environmental friendly catalysts for phenol hydroxylation with H2O2

    Directory of Open Access Journals (Sweden)

    Yuxin Jia et al

    2007-01-01

    Full Text Available A series of diatomite catalysts were treated and characterized. For the first time, the resulting materials were used in catalysis for the hydroxylation of phenol with H2O2 and showed very high hydroxylation activity due to the Fe species in the diatomite. The effect of HCl treatment, contents of catalysts and H2O2 were investigated and the active components of diatomite were discussed. The results show that diatomite is the promising candidate for industrial output due to their high catalytic activity, easy physical separation and very low costs.

  15. Alternate switching between MFC and MEC for H2O2 synthesis and residual removal in Bioelectro-Fenton system

    DEFF Research Database (Denmark)

    Zhang, Yifeng; Angelidaki, Irini

    2016-01-01

    Sustainable H2O2 supply and elimination of residual H2O2 are two key challenges to the Fenton processes treating recalcitrant contaminants. In this study, an innovative Bioelectro-Fenton system capable of alternate switching between microbial electrolysis cell (MEC) and microbial fuel cell (MFC......) mode of operation was developed to meet the challenges. In the MEC mode, H2O2 was electrochemically produced which reacts with Fenton’s reagent (Fe II) to form hydroxyradical. The residual H2O2 (unused H2O2) is removed as electron acceptor by switching the system to MFC mode. Complete decolorization...

  16. H2O2 can Increase Lignin Disintegration and Decrease Cellulose Decomposition in the Process of Solid-State Fermentation (SSF by Aspergillus oryzae Using Corn Stalk as Raw Materials

    Directory of Open Access Journals (Sweden)

    Zhicai Zhang

    2014-04-01

    Full Text Available H2O2 is both bactericidal and the main oxidant responsible for lignin degradation reaction catalyzed by manganese peroxidase (MnP and lignin peroxidase (LiP. Thus, H2O2 treatment of corn stalk and the implementation of solid-substrate fermentation (SSF is possible to increase the removal rate of lignin from stalk in the process of SSF and after SSF, while avoiding the need to sterilize the raw materials. To demonstrate this approach, SSF was initially carried out using corn stalk pretreated with different concentrations of H2O2 as a substrate. A. oryzae was found to grow well in the 3% H2O2-pretreated corn stalk. H2O2-pretreated corn stalk showed increased MnP and LiP synthesis and disintegration of lignin, but inhibited cellulase synthesis and cellulose degradation. Production of the SSF (200 g on the 10th day was hydrolyzed in the presence of additional 600 mL different concentration of H2O2 aqueous solution. The total removal of lignin (73.15% of hydrolysis for 10 h at 3% H2O2 solution was highest and far higher than that at the 12th day, as achieved by conventional SSF. Applying this strategy in practice may shorten the time of lignin degradation, increase the removal of lignin, and decrease the loss of cellulose. Thus, this study has provided a foundation for further study saccharification of corn stalk.

  17. Energetic Valorization of Wet Olive Mill Wastes through a Suitable Integrated Treatment: H2O2 with Lime and Anaerobic Digestion

    Directory of Open Access Journals (Sweden)

    Alessio Siciliano

    2016-11-01

    Full Text Available In the Mediterranean region, the disposal of residues of olive oil industries represents an important environmental issue. In recent years, many techniques were proposed to improve the characteristics of these wastes with the aim to use them for methane generation in anaerobic digestion processes. Nevertheless, these techniques, in many cases, result costly as well as difficult to perform. In the present work, a simple and useful process that exploits H2O2 in conjunction with lime is developed to enhance the anaerobic biodegradability of wet olive mill wastes (WMOW. Several tests were performed to investigate the influence of lime amount and H2O2 addition modality. The treatment efficiency was positively affected by the increase of lime dosage and by the sequential addition of hydrogen peroxide. The developed process allows reaching phenols abatements up to 80% and volatile fatty acids productions up to 90% by using H2O2 and Ca(OH2 amounts of 0.05 gH2O2/gCOD and 35 g/L, respectively. The results of many batch anaerobic digestion tests, carried out by means of laboratory equipment, proved that the biogas production from fresh wet olive mill wastes is hardly achievable. On the contrary, organic matter abatements, around to 78%, and great methane yields, up to 0.34–0.35 LCH4/gCODremoved, were obtained on pretreated wastes.

  18. A glassy carbon electrode modified with a film composed of cobalt oxide nanoparticles and graphene for electrochemical sensing of H2O2

    International Nuclear Information System (INIS)

    Li, Su-Juan; Du, Ji-Min; Zhang, Jia-Ping; Zhang, Meng-Jie; Chen, Jing

    2014-01-01

    We have prepared a graphene-based hybrid nanomaterial by electrochemical deposition of cobalt oxide nanoparticles (CoOxNPs) on the surface of electrochemically reduced graphene oxide deposited on a glassy carbon electrode (GCE). Scanning electron microscopy and cyclic voltammetry were used to characterize the immobilized nanoparticles. Electrochemical determination of H 2 O 2 is demonstrated with the modified GCE at pH 7. Compared to GCEs modified with CoO x NPs or graphene sheets only, the new electrode displays larger oxidative current response to H 2 O 2 , probably due to the synergistic effects between the graphene sheets and the CoO x NPs. The sensor responds to H 2 O 2 with a sensitivity of 148.6 μA mM −1 cm −2 and a linear response range from 5 μM to 1 mM. The detection limit is 0.2 μM at a signal to noise ratio (SNR) of three. The method was successfully applied to the determination of H 2 O 2 in hydrogen peroxide samples. (author)

  19. Expression of an alfalfa (Medicago sativa L.) peroxidase gene in transgenic Arabidopsis thaliana enhances resistance to NaCl and H2O2.

    Science.gov (United States)

    Teng, K; Xiao, G Z; Guo, W E; Yuan, J B; Li, J; Chao, Y H; Han, L B

    2016-05-23

    Peroxidases (PODs) are enzymes that play important roles in catalyzing the reduction of H2O2 and the oxidation of various substrates. They function in many different and important biological processes, such as defense mechanisms, immune responses, and pathogeny. The POD genes have been cloned and identified in many plants, but their function in alfalfa (Medicago sativa L.) is not known, to date. Based on the POD gene sequence (GenBank accession No. L36157.1), we cloned the POD gene in alfalfa, which was named MsPOD. MsPOD expression increased with increasing H2O2. The gene was expressed in all of the tissues, including the roots, stems, leaves, and flowers, particularly in stems and leaves under light/dark conditions. A subcellular analysis showed that MsPOD was localized outside the cells. Transgenic Arabidopsis with MsPOD exhibited increased resistance to H2O2 and NaCl. Moreover, POD activity in the transgenic plants was significantly higher than that in wild-type Arabidopsis. These results show that MsPOD plays an important role in resistance to H2O2 and NaCl.

  20. Degradation of n-butylparaben and 4-tert-octylphenol in H2O2/UV system

    International Nuclear Information System (INIS)

    BLedzka, Dorota; Gryglik, Dorota; Olak, Magdalena; Gebicki, Jerzy L.; Miller, Jacek S.

    2010-01-01

    The degradation of two endocrine disrupting compounds: n-butylparaben (BP) and 4-tert-octylphenol (OP) in the H 2 O 2 /UV system was studied. The effect of operating variables: initial hydrogen peroxide concentration, initial substrate concentration, pH of the reaction solution and photon fluency rate of radiation at 254 nm on reaction rate was investigated. The influence of hydroxyl radical scavengers, humic acid and nitrate anion on reaction course was also studied. A very weak scavenging effect during BP degradation was observed indicating reactions different from hydroxyl radical oxidation. The second-order rate constants of BP and OP with OH radicals were estimated to be 4.8x10 9 and 4.2x10 9 M -1 s -1 , respectively. For BP the rate constant equal to 2.0x10 10 M -1 s -1 was also determined using water radiolysis as a source of hydroxyl radicals.

  1. Remediation of diesel-contaminated soils using catalyzed hydrogen peroxide: a laboratory evaluation

    International Nuclear Information System (INIS)

    Xu, P.; Achari, G.; Mahmoud, M.; Joshi, R.C.

    2002-01-01

    This paper presents the results of a laboratory investigation conducted to determine the optimum amount of Fenton's reagent that allows for effective treatment of diesel-contaminated soils. Two types of soils spiked with 5,000 mg/kg diesel fuel were treated in vial reactors with varying concentrations and volumes of hydrogen peroxide. Additionally, Ottawa sand spiked with 5,000 mg/kg of diesel was treated with different H 2 O 2 to iron ratios. The gases produced during the remediation process were measured and analyzed to evaluate the oxidation of diesel range organics. As much as 40 % of diesel range organics was removed when 5 grams of silty clay were treated with 20 mL of 20 % H 2 O 2 . The same concentration and volume of hydrogen peroxide removed about 63 % of diesel range organics from sandy silt. The optimal molar ratio of H 2 O 2 : iron catalyst was found to vary between 235:1 to 490:1. (author)

  2. Degradation characteristic of monoazo, diazo and anthraquinone dye by UV / H2O2 process

    Science.gov (United States)

    Abidin, Che Zulzikrami Azner; Fahmi, Muhammad Ridwan; Fazara, Md Ali Umi; Nadhirah, Siti Nurfatin

    2014-10-01

    In this study, the degradation characteristic of monoazo, diazo and anthraquinone dye by UV / H2O2 process was evaluated based on the trend of color, chemical oxygen demand (COD) and total organic carbon (TOC) removal. Three types of dyes consist of monoazo, diazo and anthraquinone dyes were used to compare the degradation mechanism of the dyes. The UV / H2O2 experiments were conducted in a laboratory scale cylindrical glass reactor operated in semi-batch mode. The UV/Vis characterization of monoazo, diazo and anthraquinone dye indicated that the rapid degradation of the dyes by UV / H2O2 process is meaningful with respect to decolourization, as a result of the azo bonds and substitute antraquinone chromophore degradation. However, this process is not efficient for aromatic amines removal. The monoazo MO was difficult to be decolorized than diazo RR120 dye, which imply that number of sulphonic groups in the dye molecules determines the reactivity with hydroxyl radical. The increased in COD removal is the evidence for oxidation and decreased in carbon content of dye molecules. TOC removal analysis shows that low TOC removal of monoazo MO and diazo RR120, as compared to anthraquinone RB19 may indicate an accumulation of by-products that are resistant to the H2O2 photolysis.

  3. Emission noise spectrum in a premixed H2-O2-N2 flame

    NARCIS (Netherlands)

    Alkemade, C.T.J.; Hooymayers, H.P.; Lijnse, P.L.; Vierbergen, T.J.M.J.

    Experimental noise spectra in the frequency range of 15–105 Hz are reported for the thermal emission of the first resonance doublet of Na and K in a premixed H2-O2-N2 flame, and for the flame background emission. Under certain conditions, low-frequency peaks arise in the noise spectrum below 100 Hz,

  4. Active sites and mechanisms for H2O2 decomposition over Pd catalysts

    Science.gov (United States)

    Plauck, Anthony; Stangland, Eric E.; Dumesic, James A.; Mavrikakis, Manos

    2016-01-01

    A combination of periodic, self-consistent density functional theory (DFT-GGA-PW91) calculations, reaction kinetics experiments on a SiO2-supported Pd catalyst, and mean-field microkinetic modeling are used to probe key aspects of H2O2 decomposition on Pd in the absence of cofeeding H2. We conclude that both Pd(111) and OH-partially covered Pd(100) surfaces represent the nature of the active site for H2O2 decomposition on the supported Pd catalyst reasonably well. Furthermore, all reaction flux in the closed catalytic cycle is predicted to flow through an O–O bond scission step in either H2O2 or OOH, followed by rapid H-transfer steps to produce the H2O and O2 products. The barrier for O–O bond scission is sensitive to Pd surface structure and is concluded to be the central parameter governing H2O2 decomposition activity. PMID:27006504

  5. Utilisation of factorial experiments for the UV/H2O2 process in a ...

    African Journals Online (AJOL)

    Phenol oxidative degradation kinetics were not significantly influenced by pH or hardness of the solution to be treated, as is predicted by factorial experiments. On the other hand, initial H2O2 concentration, initial phenol concentration and temperature significantly influenced the efficiency of the process. Optimal values were ...

  6. Characterization and optimization of cathodic conditions for H2O2 synthesis in microbial electrochemical cells

    Science.gov (United States)

    Cathode potential and O2 supply methods were investigated to improve H2O2 synthesis in an electrochemical cell, and optimal cathode conditions were applied for microbial electrochemical cells (MECs). Using aqueous O2 for the cathode significantly improved current density, but H2...

  7. Search Directions for Direct H2O2 Synthesis Catalysts Starting from Au-12 Nanoclusters

    DEFF Research Database (Denmark)

    Grabow, Lars; Larsen, Britt Hvolbæk; Falsig, Hanne

    2012-01-01

    that the rate of H2O2 and H2O formation can be determined from a single descriptor, namely, the binding energy of oxygen (E-O). Our model predicts the search direction starting from an Au-12 nanocluster for an optimal catalyst in terms of activity and selectivity for direct H2O2 synthesis. Taking also stability......We present density functional theory calculations on the direct synthesis of H2O2 from H-2 and O-2 over an Au-12 corner model of a gold nanoparticle. We first show a simple route for the direct formation of H2O2 over a gold nanocatalyst, by studying the energetics of 20 possible elementary...... reactions involved in the oxidation of H-2 by O-2. The unwanted side reaction to H2O is also considered. Next we evaluate the degree of catalyst control and address the factors controlling the activity and the selectivity. By combining well-known energy scaling relations with microkinetic modeling, we show...

  8. Kinetic model describing the UV/H2O2 photodegradation of phenol from water

    Directory of Open Access Journals (Sweden)

    Rubio-Clemente Ainhoa

    2017-01-01

    Full Text Available A kinetic model for phenol transformation through the UV/H2O2 system was developed and validated. The model includes the pollutant decomposition by direct photolysis and HO•, HO2• and O2 •- oxidation. HO• scavenging effects of CO3 2-, HCO3 -, SO4 2- and Cl- were also considered, as well as the pH changes as the process proceeds. Additionally, the detrimental action of the organic matter and reaction intermediates in shielding UV and quenching HO• was incorporated. It was observed that the model can accurately predict phenol abatement using different H2O2/phenol mass ratios (495, 228 and 125, obtaining an optimal H2O2/phenol ratio of 125, leading to a phenol removal higher than 95% after 40 min of treatment, where the main oxidation species was HO•. The developed model could be relevant for calculating the optimal level of H2O2 efficiently degrading the pollutant of interest, allowing saving in costs and time.

  9. Removal of Nitrate by Zero Valent Iron in the Presence of H2O2

    Directory of Open Access Journals (Sweden)

    M.R. Samarghandi

    2014-01-01

    Full Text Available Background & Aims: Nitrate is the oxidation state of nitrogen compounds, which is founded in water resources that contaminated by municipal, industrial and agricultural waste water. If nitrate leek in to ground water resources, it can cause health problems. Material and Methods: Removal of nitrate from ground water by iron powder in the presence of H2O2 was investigated. Experiments have been done by use of 250 ml of water samples containing 100 mg/L nitrate in various condition. Various parameters such as pH (3, 5, 7, 9, iron dosage (10, 15, 20, 30 g/L, initial H2O2 concentration (5, 10, 15, 20 ml/L and contact time (10-120 min. Results: Obtained results shows the removal of nitrate was increased by pH reduction, increment of iron mass and contact time. In addition, nitrate reduction was increased by increment of initial H2O2 concentration up to 15 ml/L. High removal was observed at pH=3, iron mass=30 g/L, contact time equal 120 min and H2O2 concentration=15 ml/L. At above condition, upon 98% of nitrate was removed. Conclusion: In summary, this method is simple, low cost and effective for removal of nitrate from ground water and industrial activity.

  10. Mechanisms in manganese catalysed oxidation of alkenes with H2O2

    NARCIS (Netherlands)

    Saisaha, Pattama; de Boer, Johannes W.; Browne, Wesley R.

    2013-01-01

    The development of new catalytic systems for cis-dihydroxylation and epoxidation of alkenes, based on atom economic and environmentally friendly concepts, is a major contemporary challenge. In recent years, several systems based on manganese catalysts using H2O2 as the terminal oxidant have been

  11. Combined amino acids modulation with H 2 O 2 stress for ...

    African Journals Online (AJOL)

    Strategies of amino acids addition coupled with H2O2 stresses were developed for glutathione (GSH) overproduction in high cell density (HCD) cultivation of Candida utilis. Based on the fact that glycine shows two functions of promoting cells growth as well as GSH production, precursor amino acids modulations of feeding ...

  12. Effective Reuse of Electroplating Rinse Wastewater by Combining PAC with H2O2/UV Process.

    Science.gov (United States)

    Yen, Hsing Yuan; Kang, Shyh-Fang; Lin, Chen Pei

    2015-04-01

    This study evaluated the performance of treating electroplating rinse wastewater by powder activated carbon (PAC) adsorption, H2O2/UV oxidation, and their combination to remove organic compounds and heavy metals. The results showed that neither the process of PAC adsorption nor H2O2/UV oxidation could reduce COD to 100 mg/L, as enforced by the Taiwan Environmental Protection Agency. On the other hand, the water sample treated by the combined approach of using PAC (5 g/L) pre-adsorption and H2O2/UV post-oxidation (UV of 64 W, H2O2 of 100 mg/L, oxidation time of 90 min), COD and DOC were reduced to 8.2 mg/L and 3.8 mg/L, respectively. Also, the combined approach reduced heavy metals to meet the effluent standards and to satisfy the in-house water reuse criteria for the electroplating factory. The reaction constant analysis indicated that the reaction proceeded much more rapidly for the combined process. Hence, it is a more efficient, economic and environmentally friendly process.

  13. X-ray irradiation activates K+ channels via H2O2 signaling.

    Science.gov (United States)

    Gibhardt, Christine S; Roth, Bastian; Schroeder, Indra; Fuck, Sebastian; Becker, Patrick; Jakob, Burkhard; Fournier, Claudia; Moroni, Anna; Thiel, Gerhard

    2015-09-09

    Ionizing radiation is a universal tool in tumor therapy but may also cause secondary cancers or cell invasiveness. These negative side effects could be causally related to the human-intermediate-conductance Ca2+-activated-K+-channel (hIK), which is activated by X-ray irradiation and affects cell proliferation and migration. To analyze the signaling cascade downstream of ionizing radiation we use genetically encoded reporters for H2O2 (HyPer) and for the dominant redox-buffer glutathione (Grx1-roGFP2) to monitor with high spatial and temporal resolution, radiation-triggered excursions of H2O2 in A549 and HEK293 cells. The data show that challenging cells with ≥1 Gy X-rays or with UV-A laser micro-irradiation causes a rapid rise of H2O2 in the nucleus and in the cytosol. This rise, which is determined by the rate of H2O2 production and glutathione-buffering, is sufficient for triggering a signaling cascade that involves an elevation of cytosolic Ca2+ and eventually an activation of hIK channels.

  14. Histone peptide AKRHRK enhances H2O2-induced DNA damage and alters its site specificity

    International Nuclear Information System (INIS)

    Midorikawa, Kaoru; Murata, Mariko; Kawanishi, Shosuke

    2005-01-01

    Histone proteins are involved in compaction of DNA and the protection of cells from oxygen toxicity. However, several studies have demonstrated that the metal-binding histone reacts with H 2 O 2 , leading to oxidative damage to a nucleobase. We investigated whether histone can accelerate oxidative DNA damage, using a minimal model for the N-terminal tail of histone H4, CH 3 CO-AKRHRK-CONH 2 , which has a metal-binding site. This histone peptide enhanced DNA damage induced by H 2 O 2 and Cu(II), especially at cytosine residues, and induced additional DNA cleavage at the 5'-guanine of GGG sequences. The peptide also enhanced the formation of 8-oxo-7,8-dihydro-2'-deoxyguanosine and ESR spin-trapping signal from H 2 O 2 and Cu(II). Cyclic redox reactions involving histone-bound Cu(II) and H 2 O 2 , may give rise to multiple production of radicals leading to multiple hits in DNA. It is noteworthy that the histone H4 peptide with specific sequence AKRHRK can cause DNA damage rather than protection under metal-overloaded condition

  15. Degradation characteristic of monoazo, diazo and anthraquinone dye by UV/H2O2 process

    International Nuclear Information System (INIS)

    Abidin, Che Zulzikrami Azner; Fahmi, Muhammad Ridwan; Fazara, Md Ali Umi; Nadhirah, Siti Nurfatin

    2014-01-01

    In this study, the degradation characteristic of monoazo, diazo and anthraquinone dye by UV/H 2 O 2 process was evaluated based on the trend of color, chemical oxygen demand (COD) and total organic carbon (TOC) removal. Three types of dyes consist of monoazo, diazo and anthraquinone dyes were used to compare the degradation mechanism of the dyes. The UV/H 2 O 2 experiments were conducted in a laboratory scale cylindrical glass reactor operated in semi-batch mode. The UV/Vis characterization of monoazo, diazo and anthraquinone dye indicated that the rapid degradation of the dyes by UV/H 2 O 2 process is meaningful with respect to decolourization, as a result of the azo bonds and substitute antraquinone chromophore degradation. However, this process is not efficient for aromatic amines removal. The monoazo MO was difficult to be decolorized than diazo RR120 dye, which imply that number of sulphonic groups in the dye molecules determines the reactivity with hydroxyl radical. The increased in COD removal is the evidence for oxidation and decreased in carbon content of dye molecules. TOC removal analysis shows that low TOC removal of monoazo MO and diazo RR120, as compared to anthraquinone RB19 may indicate an accumulation of by-products that are resistant to the H 2 O 2 photolysis

  16. H2O2-induced higher order chromatin degradation: A novel ...

    Indian Academy of Sciences (India)

    Unknown

    mediator of oxidative stress, can also cause genomic damage indirectly. Thus, H2O2 at pathologically relevant concentrations rapidly induces higher order chromatin degradation (HOCD), i.e. enzymatic ... clease works through a single strand scission mechanism ... a great mutagenic risk to the surviving cells, because en-.

  17. Response properties of the genetically encoded optical H2O2 sensor HyPer.

    Science.gov (United States)

    Weller, Jonathan; Kizina, Kathrin M; Can, Karolina; Bao, Guobin; Müller, Michael

    2014-11-01

    Reactive oxygen species mediate cellular signaling and neuropathologies. Hence, there is tremendous interest in monitoring (sub)cellular redox conditions. We evaluated the genetically engineered redox sensor HyPer in mouse hippocampal cell cultures. Two days after lipofection, neurons and glia showed sufficient expression levels, and H2O2 reversibly and dose-dependently increased the fluorescence ratio of cytosolic HyPer. Yet, repeated H2O2 treatment caused progressively declining responses, and with millimolar doses an apparent recovery started while H2O2 was still present. Although HyPer should be H2O2 specific, it seemingly responded also to other oxidants and altered cell-endogenous superoxide production. Control experiments with the SypHer pH sensor confirmed that the HyPer ratio responds to pH changes, decreasing with acidosis and increasing during alkalosis. Anoxia/reoxygenation evoked biphasic HyPer responses reporting apparent reduction/oxidation; replacing Cl(-) exerted only negligible effects. Mitochondria-targeted HyPer readily responded to H2O2-albeit less intensely than cytosolic HyPer. With ratiometric two-photon excitation, H2O2 increased the cytosolic HyPer ratio. Time-correlated fluorescence-lifetime imaging microscopy (FLIM) revealed a monoexponential decay of HyPer fluorescence, and H2O2 decreased fluorescence lifetimes. Dithiothreitol failed to further reduce HyPer or to induce reasonable FLIM and two-photon responses. By enabling dynamic recordings, HyPer is superior to synthetic redox-sensitive dyes. Its feasibility for two-photon excitation also enables studies in more complex preparations. Based on FLIM, quantitative analyses might be possible independent of switching excitation wavelengths. Yet, because of its pronounced pH sensitivity, adaptation to repeated oxidation, and insensitivity to reducing stimuli, HyPer responses have to be interpreted carefully. For reliable data, side-by-side pH monitoring with SypHer is essential. Copyright

  18. Kinetics of Platinum-Catalyzed Decomposition of Hydrogen Peroxide

    Science.gov (United States)

    Vetter, Tiffany A.; Colombo, D. Philip, Jr.

    2003-07-01

    CIBA Vision Corporation markets a contact lens cleaning system that consists of an AOSEPT disinfectant solution and an AOSEPT lens cup. The disinfectant is a buffered 3.0% m/v hydrogen peroxide solution and the cup includes a platinum-coated AOSEPT disc. The hydrogen peroxide disinfects by killing bacteria, fungi, and viruses found on the contact lenses. Because the concentration of hydrogen peroxide needed to disinfect is irritating to eyes, the hydrogen peroxide needs to be neutralized, or decomposed, before the contact lenses can be used again. A general chemistry experiment is described where the kinetics of the catalyzed decomposition of the hydrogen peroxide are studied by measuring the amount of oxygen generated as a function of time. The order of the reaction with respect to the hydrogen peroxide, the rate constant, and the energy of activation are determined. The integrated rate law is used to determine the time required to decompose the hydrogen peroxide to a concentration that is safe for eyes.

  19. Decolorization of methylene blue in layered manganese oxide suspension with H2O2

    International Nuclear Information System (INIS)

    Zhang Lili; Nie Yulun; Hu Chun; Hu Xuexiang

    2011-01-01

    Highlights: → Layered birnessite-type manganese oxides exhibited a well-crystallized octahedral layer (OL) structure with β-MnOOH, α-MnOOH and γ-Mn 3 O 4 . → The catalyst was highly effective for the decolorization and degradation of methylene blue in the presence of H 2 O 2 at neutral pH. → The 1 O 2 and O 2 · - were the main reactive oxygen species in the reaction. - Abstract: Layered birnessite-type manganese oxides (Na-OL-1) were prepared via a redox reaction involving MnO 4 - and Mn 2+ under markedly alkaline conditions. According to the XRD analysis, the resulting material exhibited a well-crystallized octahedral layer (OL) structure with several different phases, including β-MnOOH, α-MnOOH and γ-Mn 3 O 4 . The catalyst was highly effective for the decolorization and degradation of methylene blue (MB) in the presence of H 2 O 2 at neutral pH. The tested MB was completely decolorized in Na-OL-1 suspension by the fraction dosing of H 2 O 2 (556.5 mM at the beginning and then 183.8 mM at 40 min). Based on the studies of electron spin resonance and the effect of radical scavengers, the 1 O 2 and O 2 · - were the main reactive oxygen species (ROS) in the reaction. It was found that both oxygen and ROS were generated from the decomposition of H 2 O 2 in Na-OL-1 suspension, wherein the decomposition pathways were proposed. The generation of H 2 O 2 in Na-OL-1 suspension at air atmosphere indicated that the existence of multivalent manganese oxides greatly enhanced the interfacial electron transfer, leading to the high activity of Na-OL-1.

  20. Activation of aqueous hydrogen peroxide for non-catalyzed dihydroperoxidation of ketones by azeotropic removal of water.

    Science.gov (United States)

    Starkl Renar, K; Pečar, S; Iskra, J

    2015-09-28

    Cyclic and acyclic ketones were selectively converted to gem-dihydroperoxides in 72-99% yield with 30% aq. hydrogen peroxide by azeotropic distillation of water from the reaction mixture without any catalyst. The reactions were more selective than with 100% H2O2 and due to neutral conditions also less stable products could be obtained.

  1. Kinetics and oxidative mechanism for H2O2-enhanced iron-mediated aeration (IMA) treatment of recalcitrant organic compounds in mature landfill leachate

    International Nuclear Information System (INIS)

    Deng Yang; Englehardt, James D.

    2009-01-01

    A hydrogen peroxide (H 2 O 2 )-enhanced iron (Fe 0 )-mediated aeration (IMA) process has been recently demonstrated to effectively remove organic wastes from mature landfill leachate. In this paper, the kinetics and oxidative mechanisms of the enhanced IMA treatment were studied. Bench-scale full factorial tests were conducted in an orbital shaker reactor for treatment of a mature leachate with an initial chemical oxygen demand (COD) of 900-1200 mg/L. At the maximum aeration rate (8.3 mL air/min mL sample), process variables significantly influencing the rates of H 2 O 2 decay and COD removal were pH (3.0-8.0), initial H 2 O 2 doses (0.21-0.84 M), and Fe 0 surface area concentrations (0.06-0.30 m 2 /L). Empirical kinetic models were developed and verified for the degradation of H 2 O 2 and COD. High DO maintained by a high aeration rate slowed the H 2 O 2 self-decomposition, accelerated Fe 0 consumption, and enhanced the COD removal. In hydroxyl radical (OH·) scavenging tests, the rate of removal of glyoxylic acid (target compound) was not inhibited by the addition of para-chlorobenzoic acid (OH· scavenger) at pH 7.0-7.5, ruling out hydroxyl radical as the principal oxidant in neutral-weakly basic solution. These experimental results show that this enhanced IMA technology is a potential alternative for the treatment of high strength recalcitrant organic wastewaters.

  2. Kinetics and oxidative mechanism for H2O2-enhanced iron-mediated aeration (IMA) treatment of recalcitrant organic compounds in mature landfill leachate.

    Science.gov (United States)

    Deng, Yang; Englehardt, James D

    2009-09-30

    A hydrogen peroxide (H(2)O(2))-enhanced iron (Fe(0))-mediated aeration (IMA) process has been recently demonstrated to effectively remove organic wastes from mature landfill leachate. In this paper, the kinetics and oxidative mechanisms of the enhanced IMA treatment were studied. Bench-scale full factorial tests were conducted in an orbital shaker reactor for treatment of a mature leachate with an initial chemical oxygen demand (COD) of 900-1200 mg/L. At the maximum aeration rate (8.3 mL air/min mL sample), process variables significantly influencing the rates of H(2)O(2) decay and COD removal were pH (3.0-8.0), initial H(2)O(2) doses (0.21-0.84 M), and Fe(0) surface area concentrations (0.06-0.30 m(2)/L). Empirical kinetic models were developed and verified for the degradation of H(2)O(2) and COD. High DO maintained by a high aeration rate slowed the H(2)O(2) self-decomposition, accelerated Fe(0) consumption, and enhanced the COD removal. In hydroxyl radical (OH*) scavenging tests, the rate of removal of glyoxylic acid (target compound) was not inhibited by the addition of para-chlorobenzoic acid (OH* scavenger) at pH 7.0-7.5, ruling out hydroxyl radical as the principal oxidant in neutral-weakly basic solution. These experimental results show that this enhanced IMA technology is a potential alternative for the treatment of high strength recalcitrant organic wastewaters.

  3. Luteolin Prevents H2O2-Induced Apoptosis in H9C2 Cells through Modulating Akt-P53/Mdm2 Signaling Pathway

    Directory of Open Access Journals (Sweden)

    Hong Chang

    2016-01-01

    Full Text Available Introduction. Luteolin, a falconoid compound in many Chinese herbs and formula, plays important roles in cardiovascular diseases. The underlying mechanism of luteolin remains to be further elaborated. Methods. A model of hydrogen peroxide- (H2O2- induced H9C2 cells apoptosis was established. Cell viabilities were examined with an MTT assay. 2′,7′-Dichlorofluorescin diacetate (DCFH-DA and flow cytometry were used to detect ROS level and apoptosis rate, respectively. The expressions of signaling proteins related to apoptosis were analyzed by western blot and mRNA levels were detected by real-time polymerase chain reaction (PCR. Quercetin was applied as positive drug. Results. Incubation with various concentrations of H2O2 (0, 50, 100, and 200 μM for 1 h caused dose-dependent loss of cell viability and 100 μM H2O2 reduced the cell viability to approximately 50%. Treatments with luteolin and quercetin protected cells from H2O2-induced cytotoxicity and reduced cellular ROS level and apoptosis rate. Moreover, luteolin could downregulate the expressions of Bax, caspase-8, cleaved-caspase-3, and p53 in apoptotic signaling pathway. Further study showed that the expressions of Akt, Bcl-2, and Mdm2 were upregulated by luteolin. Conclusion. Luteolin protects H9C2 cells from H2O2-induced apoptosis. The protective and antiapoptotic effects of luteolin could be mediated by regulating the Akt-P53/Mdm2 apoptotic pathway.

  4. NO accumulation alleviates H2 O2 -dependent oxidative damage induced by Ca(NO3 )2 stress in the leaves of pumpkin-grafted cucumber seedlings.

    Science.gov (United States)

    Li, Lin; Shu, Sheng; Xu, Qing; An, Ya-Hong; Sun, Jin; Guo, Shi-Rong

    2017-05-01

    Nitric oxide (NO) and hydrogen peroxide (H 2 O 2 ), two important signaling molecules, are stimulated in plants by abiotic stresses. In this study, we investigated the role of NO and its interplay with H 2 O 2 in the response of self-grafted (S-G) and salt-tolerant pumpkin-grafted (Cucurbita maxima × C. moschata) cucumber seedlings to 80 mM Ca(NO 3 ) 2 stress. Endogenous NO and H 2 O 2 production in S-G seedlings increased in a time-dependent manner, reaching maximum levels after 24 h of Ca(NO 3 ) 2 stress. In contrast, a transient increase in NO production, accompanied by H 2 O 2 accumulation, was observed at 2 h in rootstock-grafted plants. N w -Nitro-l-Arg methyl ester hydrochloride (l-NAME), an inhibitor of nitric oxide synthase (NOS), tungstate, an inhibitor of nitrate reductase (NR), and 2-(4-carboxyphenyl)-4,4,5,5-tetramethy-limidazoline-1-oxyl-3-oxide (cPTIO), a scavenger of NO, were found to significantly inhibit NO accumulation induced by salt stress in rootstock-grafted seedlings. H 2 O 2 production was unaffected by these stress conditions. Ca(NO 3 ) 2 stress-induced NO accumulation was blocked by pretreatment with an H 2 O 2 scavenger (dimethylthiourea, DMTU) and an inhibitor of NADPH oxidase (diphenyleneiodonium, DPI). In addition, maximum quantum yield of PSII (Fv/Fm), as well as the activities and transcript levels of antioxidant enzymes, were significantly decreased by salt stress in rootstock grafted seedlings after pretreatment with these above inhibitors; antioxidant enzyme transcript levels and activities were higher in rootstock-grafted seedlings compared with S-G seedlings. These results suggest that rootstock grafting could alleviate the oxidative damage induced by Ca(NO 3 ) 2 stress in cucumber seedlings, an effect that may be attributable to the involvement of NO in H 2 O 2 -dependent antioxidative metabolism. © 2016 Scandinavian Plant Physiology Society.

  5. [Effect of germacrone in alleviating HUVECs damaged by H2O2-induced oxidative stress].

    Science.gov (United States)

    Chen, Qiong-Fang; Wang, Gang; Tang, Li-Qing; Yu, Xian-Wen; Li, Zhao-Fei; Yang, Xiu-Fen

    2017-09-01

    This study focuses on the protective effect of germacrone on human umbilical vein endothelial cells(HUVECs) damaged by H2O2-induced oxidative stress and its possible mechanisms. The oxidative damage model was established by using 500 μmol•L⁻¹ H2O2 to treat HUVECs for 3 hours, and then protected with different concentrations of germacrone for 24 hours. The effect of germacrone on cell viability of HUVECs damaged by H2O2 was detected by MTT. The contents of PGI2, TXB2, ET-1, t-PA, PAI-1, TNF-α and IL-6 were detected by ELISA. The content of NO was detected by using nitrate reductase method. Colorimetry was used to detect NOS and GSH-Px. The contents of MDA, SOD and LDH were detected by TBA, WST-1 and microplate respectively. Apoptosis was observed by Hoechst 33258 fluorescent staining. The mRNA expressions of Bax, Bcl-2 and Caspase-3 in cells were detected by RT-PCR. The results showed that the cell damage rate was 52% after treated with 500 μmol•L⁻¹ H2O2 for 3 hours. The cell activity was increasing with the rise of germacrone concentration within the range of 20-200 mol•L⁻¹. Compared with normal group, the contents of PGI2, NO, T-NOS, t-PA, SOD, GSH-Px and Bcl-2 mRNA expressions were lower after damaged with H2O2. The contents of PAI-1, ET-1, IL-6, TNF-α, TXB2, LDH, MDA, Bax mRNA and Caspase-3 mRNA expressions were increased. Compared with model group, the contents of PGI2, NO, T-NOS, t-PA, SOD, GSH-Px and Bcl-2 mRNA expressions were increased after treated with germacrone. The contents of PAI-1, ET-1, IL-6, TNF-α, TXB2, LDH, MDA, Bax mRNA and Caspase-3 mRNA expressions were lower after treated with germacrone. According to Hoechst 33258 fluorescence staining, compared with normal group, the cell membrane and the nucleus showed strong dense blue fluorescence, and the number of cells significantly decreased in model group. Compared with model group, blue fluorescence intensity decreased in drug group. The above findings demonstrate that

  6. Effects of Downregulation of MicroRNA-181a on H2O2-Induced H9c2 Cell Apoptosis via the Mitochondrial Apoptotic Pathway

    Directory of Open Access Journals (Sweden)

    Lei Wang

    2014-01-01

    Full Text Available Glutathione peroxidase-1 (GPx1 is a pivotal intracellular antioxidant enzyme that enzymatically reduces hydrogen peroxide to water to limit its harmful effects. This study aims to identify a microRNA (miRNA that targets GPx1 to maintain redox homeostasis. Dual luciferase assays combined with mutational analysis and immunoblotting were used to validate the bioinformatically predicted miRNAs. We sought to select miRNAs that were responsive to oxidative stress induced by hydrogen peroxide (H2O2 in the H9c2 rat cardiomyocyte cell line. Quantitative real-time PCR (qPCR demonstrated that the expression of miR-181a in H2O2-treated H9c2 cells was markedly upregulated. The downregulation of miR-181a significantly inhibited H2O2-induced cellular apoptosis, ROS production, the increase in malondialdehyde (MDA levels, the disruption of mitochondrial structure, and the activation of key signaling proteins in the mitochondrial apoptotic pathway. Our results suggest that miR-181a plays an important role in regulating the mitochondrial apoptotic pathway in cardiomyocytes challenged with oxidative stress. MiR-181a may represent a potential therapeutic target for the treatment of oxidative stress-associated cardiovascular diseases.

  7. H2O2 Synthesis Induced by Irradiation of H2O with Energetic H(+) and Ar(+) Ions at Various Temperatures

    Science.gov (United States)

    Baragiola, R. A.; Loeffler, M. J.; Raut, U.; Vidal, R. A.; Carlson, R. W.

    2004-01-01

    The detection of H2O2 on Jupiter's icy satellite Europa by the Galileo NIMS instrument presented a strong evidence for the importance of radiation effects on icy surfaces. A few experiments have investigated whether solar flux of protons incident on Europa ice could cause a significant if any H2O2 production. These published results differ as to whether H2O2 can be formed by ions impacting water at temperatures near 80 K, which are appropriate to Europa. This discrepancy may be a result of the use of different incident ion energies, different vacuum conditions, or different ways of processing the data. The latter possibility comes about from the difficulty of identifying the 3.5 m peroxide OH band on the long wavelength wing of the much stronger water 3.1 m band. The problem is aggravated by using straight line baselines to represent the water OH band with a curvature, in the region of the peroxide band, that increases with temperature. To overcome this problem, we use polynomial baselines that provide good fits to the water band and its derivative.

  8. Pilot-scale UV/H2O2 advanced oxidation process for municipal reuse water: Assessing micropollutant degradation and estrogenic impacts on goldfish (Carassius auratus L.).

    Science.gov (United States)

    Shu, Zengquan; Singh, Arvinder; Klamerth, Nikolaus; McPhedran, Kerry; Bolton, James R; Belosevic, Miodrag; Gamal El-Din, Mohamed

    2016-09-15

    Low concentrations (ng/L-μg/L) of emerging micropollutant contaminants in municipal wastewater treatment plant effluents affect the possibility to reuse these waters. Many of those micropollutants elicit endocrine disrupting effects in aquatic organisms resulting in an alteration of the endocrine system. A potential candidate for tertiary municipal wastewater treatment of these micropollutants is ultraviolet (UV)/hydrogen peroxide (H2O2) as an advanced oxidation process (AOP) which was currently applied to treat the secondary effluent of the Gold Bar Wastewater Treatment Plant (GBWWTP) in Edmonton, AB, Canada. A new approach is presented to predict the fluence-based degradation rate constants (kf') of environmentally occurring micropollutants including carbamazepine [(0.87-1.39) × 10(-3) cm(2)/mJ] and 2,4-Dichlorophenoxyacetic acid (2,4-D) [(0.60-0.91) × 10(-3) cm(2)/mJ for 2,4-D] in a medium pressure (MP) UV/H2O2 system based on a previous bench-scale investigation. Rather than using removal rates, this approach can be used to estimate the performance of the MP UV/H2O2 process for degrading trace contaminants of concern found in municipal wastewater. In addition to the ability to track contaminant removal/degradation, evaluation of the MP UV/H2O2 process was also accomplished by identifying critical ecotoxicological endpoints (i.e., estrogenicity) of the treated wastewater. Using quantitative PCR, mRNA levels of estrogen-responsive (ER) genes ERα1, ERα2, ERβ1, ERβ2 and NPR as well as two aromatase encoding genes (CYP19a and CYP19b) in goldfish (Carassius auratus L.) were measured during exposure to the GBWWTP effluent before and after MP UV/H2O2 treatment (a fluence of 1000 mJ/cm(2) and 20 mg/L of H2O2) in spring, summer and fall. Elevated expression of estrogen-responsive genes in goldfish exposed to UV/H2O2 treated effluent (a 7-day exposure) suggested that the UV/H2O2 process may induce acute estrogenic disruption to goldfish principally because

  9. Effect of H2O2 on the in vitro growth of Mycosphaerella fijiensis Cuban isolate

    Directory of Open Access Journals (Sweden)

    María I. Oloriz

    2014-04-01

    Full Text Available Black leaf streak disease (Mycosphaerella fijiensis Morelet is the main foliar disease of bananas and plantain. One of the possible mechanisms of resistance is the hypersensitive response observed in ‘Calcutta 4’ (Musa AA that involves the formation of reactive oxygen species. In order to determine the effect of H2O2 on the in vitro growth of M. fijiensis Cuban isolate CCIBP-Pf-83, several concentrations added to a culture medium PDB were tested. After seven days of incubation the mycelial dry weight was determined. It was found that with 30 mmol l-1 H2O2 in the culture medium, mycelial growth was stimulated and with 50 up to 100 mmol l-1 it decreased. The results provide elements for understanding plantpathogen interactions in this pathosystem. Key words: black leaf streak disease, in vitro culture, ROS

  10. Laser-induced photochemical reaction of aqueous maleic acid solutions containing H2O2

    International Nuclear Information System (INIS)

    Shimizu, Yuichi; Kawanishi, Shunichi; Suzuki, Nobutake

    1995-01-01

    Hydroxy acid such as glycolic, tartaric and malic acids was directly produced by XeF-laser irradiation of the N 2 -saturated maleic acid aqueous solution containing H 2 O 2 . The selectivities of these products at the maximum of tartaric acid were 71, 4, and 2% at H 2 O 2 feeding rate of 3.2 ml h -1 , respectively. On the other hand, the irradiation of maleates such as dipotassium, calcium, and disodium greatly enhanced the selectivities of tartaric acid formation to 19%, and of malic acid formation to 13%, respectively, for dipotassium maleate. It may be considered from these results that the stability of the hydroxylated intermediate radical plays an important role for the efficient formations of tartaric and malic acids. (author)

  11. Synthesis and crystal structure of trans-[Ni(pyzdcH)M 2 (H 2 O) 2 ...

    African Journals Online (AJOL)

    The determined structure of the title compound C24H20Ni2N8O20 consists of the mononuclear trans-[Ni(pyzdc)2(H2O)2], (pyzdc = pyrazine-2,3- dicarboxylate). The Ni(II) atom is hexa-coordinated by two (pyzdcH)- groups and two water molecules. The coordinated water molecules are in trans-diaxial positions and the ...

  12. Lactobacilli inactivate Chlamydia trachomatis through lactic acid but not H2O2.

    Directory of Open Access Journals (Sweden)

    Zheng Gong

    Full Text Available Lactobacillus species dominate the microbiome in the lower genital tract of most reproductive-age women. Producing lactic acid and H2O2, lactobacilli are believed to play an important role in prevention of colonization by and growth of pathogens. However, to date, there have been no reported studies characterizing how lactobacilli interact with Chlamydia trachomatis, a leading sexually transmitted bacterium. In this report, we demonstrate inactivation of C. trachomatis infectivity by culture media conditioned by Lactobacillus crispatus, L. gasseri and L. jensenii, known to be dominating organisms in the human vaginal microbiome. Lactobacillus still cultures produced lactic acid, leading to time- and concentration-dependent killing of C. trachomatis. Neutralization of the acidic media completely reversed chlamydia killing. Addition of lactic acid into Lactobacillus-unconditioned growth medium recapitulated the chlamydiacidal activity of conditioned media. The H2O2 concentrations in the still cultures were found to be comparable to those reported for the cervicovaginal fluid, but insufficient to inactivate chlamydiae. Aeration of Lactobacillus cultures by shaking markedly induced H2O2 production, but strongly inhibited Lactobacillus growth and lactic acid production, and thus severely affected acidification, leading to significantly reduced chlamydiacidal efficiency. These observations indicate lactobacilli inactivate chlamydiae primarily through maintaining acidity in a relatively hypoxic environment in the vaginal lumen with limited H2O2, which is consistent with the notion that women with higher vaginal pH are more prone to sexually transmitted C. trachomatis infection. In addition to lactic acid, formic acid and acetic acid also exhibited potent chlamydiacidal activities. Taken together, our findings imply that lowering the vaginal pH through engineering of the vaginal microbiome and other means will make women less susceptible to C

  13. Proteomic and metabolomic analysis of H2O2-induced premature senescent human mesenchymal stem cells.

    Science.gov (United States)

    Kim, Ji-Soo; Kim, Eui-Jin; Kim, Hyun-Jung; Yang, Ji-Young; Hwang, Geum-Sook; Kim, Chan-Wha

    2011-06-01

    Stress induced premature senescence (SIPS) occurs after exposure to many different sublethal stresses including H(2)O(2), hyperoxia, or tert-butylhydroperoxide. Human mesenchymal stem cells (hMSCs) exhibit limited proliferative potential in vitro, the so-called Hayflick limit. According to the free-radical theory, reactive oxygen species (ROS) might be the candidates responsible for senescence and age-related diseases. H(2)O(2) may be responsible for the production of high levels of ROS, in which the redox balance is disturbed and the cells shift into a state of oxidative stress, which subsequently leads to premature senescence with shortening telomeres. H(2)O(2) has been the most commonly used inducer of SIPS, which shares features of replicative senescence (RS) including a similar morphology, senescence-associated β-galactosidase activity, cell cycle regulation, etc. Therefore, in this study, the senescence of hMSC during SIPS was confirmed using a range of different analytical methods. In addition, we determined five differentially expressed spots in the 2-DE map, which were identified as Annexin A2 (ANXA2), myosin light chain 2 (MLC2), peroxisomal enoyl-CoA hydratase 1 (ECH1), prosomal protein P30-33K (PSMA1) and mutant β-actin by ESI-Q-TOF MS/MS. Also, proton ((1)H) nuclear magnetic resonance spectroscopy (NMR) was used to elucidate the difference between metabolites in the control and hMSCs treated with H(2)O(2). Among these metabolites, choline and leucine were identified by (1)H-NMR as up-regulated metabolites and glycine and proline were identified as down-regulated metabolites. Copyright © 2011 Elsevier Inc. All rights reserved.

  14. Cigarette smoke affects keratinocytes SRB1 expression and localization via H2O2 production and HNE protein adducts formation.

    Directory of Open Access Journals (Sweden)

    Claudia Sticozzi

    Full Text Available Scavenger Receptor B1 (SR-B1, also known as HDL receptor, is involved in cellular cholesterol uptake. Stratum corneum (SC, the outermost layer of the skin, is composed of more than 25% cholesterol. Several reports support the view that alteration of SC lipid composition may be the cause of impaired barrier function which gives rise to several skin diseases. For this reason the regulation of the genes involved in cholesterol uptake is of extreme significance for skin health. Being the first shield against external insults, the skin is exposed to several noxious substances and among these is cigarette smoke (CS, which has been recently associated with various skin pathologies. In this study we first have shown the presence of SR-B1 in murine and human skin tissue and then by using immunoblotting, immunoprecipitation, RT-PCR, and confocal microscopy we have demonstrated the translocation and the subsequent lost of SR-B1 in human keratinocytes (cell culture model after CS exposure is driven by hydrogen peroxide (H(2O(2 that derives not only from the CS gas phase but mainly from the activation of cellular NADPH oxidase (NOX. This effect was reversed when the cells were pretreated with NOX inhibitors or catalase. Furthermore, CS caused the formation of SR-B1-aldheydes adducts (acrolein and 4-hydroxy-2-nonenal and the increase of its ubiquitination, which could be one of the causes of SR-B1 loss. In conclusion, exposure to CS, through the production of H(2O(2, induced post-translational modifications of SR-B1 with the consequence lost of the receptor and this may contribute to the skin physiology alteration as a consequence of the variation of cholesterol uptake.

  15. Degradation of phenolic compounds with hydrogen peroxide catalyzed by enzyme from Serratia marcescens AB 90027.

    Science.gov (United States)

    Yao, Ri-Sheng; Sun, Min; Wang, Chun-Ling; Deng, Sheng-Song

    2006-09-01

    In this paper, the degradation of phenolic compounds using hydrogen peroxide as oxidizer and the enzyme extract from Serratia marcescens AB 90027 as catalyst was reported. With such an enzyme/H2O2 combination treatment, a high chemical oxygen demand (COD) removal efficiency was achieved, e.g., degradation of hydroquinone exceeded 96%. From UV-visible and IR spectra, the degradation mechanisms were judged as a process of phenyl ring cleavage. HPLC analysis shows that in the degradation p-benzoquinone, maleic acid and oxalic acid were formed as intermediates and that they were ultimately converted to CO2 and H2O. With the enzyme/H2O2 treatment, vanillin, hydroquinone, catechol, o-aminophenol, p-aminophenol, phloroglucinol and p-hydroxybenzaldehyde were readily degraded, whereas the degradation of phenol, salicylic acid, resorcinol, p-cholorophenol and p-nitrophenol were limited. Their degradability was closely related to the properties and positions of their side chain groups. Electron-donating groups, such as -OH, -NH2 and -OCH3 enhanced the degradation, whereas electron-withdrawing groups, such as -NO2, -Cl and -COOH, had a negative effect on the degradation of these compounds in the presence of enzyme/H2O2. Compounds with -OH at ortho and para positions were more readily degraded than those with -OH at meta positions.

  16. Nonlinear feedback drives homeostatic plasticity in H2O2 stress response

    Science.gov (United States)

    Goulev, Youlian; Morlot, Sandrine; Matifas, Audrey; Huang, Bo; Molin, Mikael; Toledano, Michel B; Charvin, Gilles

    2017-01-01

    Homeostatic systems that rely on genetic regulatory networks are intrinsically limited by the transcriptional response time, which may restrict a cell’s ability to adapt to unanticipated environmental challenges. To bypass this limitation, cells have evolved mechanisms whereby exposure to mild stress increases their resistance to subsequent threats. However, the mechanisms responsible for such adaptive homeostasis remain largely unknown. Here, we used live-cell imaging and microfluidics to investigate the adaptive response of budding yeast to temporally controlled H2O2 stress patterns. We demonstrate that acquisition of tolerance is a systems-level property resulting from nonlinearity of H2O2 scavenging by peroxiredoxins and our study reveals that this regulatory scheme induces a striking hormetic effect of extracellular H2O2 stress on replicative longevity. Our study thus provides a novel quantitative framework bridging the molecular architecture of a cellular homeostatic system to the emergence of nonintuitive adaptive properties. DOI: http://dx.doi.org/10.7554/eLife.23971.001 PMID:28418333

  17. Pilot-scale UV/H2O2 study for emerging organic contaminants decomposition.

    Science.gov (United States)

    Chu, Xiaona; Xiao, Yan; Hu, Jiangyong; Quek, Elaine; Xie, Rongjin; Pang, Thomas; Xing, Yongjie

    2016-03-01

    Human behaviors including consumption of drugs and use of personal care products, climate change, increased international travel, and the advent of water reclamation for direct potable use have led to the introduction of significant amounts of emerging organic contaminants into the aqueous environment. In addition, the lower detection limits associated with improved scientific methods of chemical analysis have resulted in a recent increase in documented incidences of these contaminants which previously were not routinely monitored in water. Such contaminants may cause known or suspected adverse ecological and/or human health effects at very low concentrations. Conventional drinking water treatment processes may not effectively remove these organic contaminants. Advanced oxidation process (AOP) is a promising treatment process for the removal of most of these emerging organic contaminants, and has been accepted worldwide as a suitable treatment process. In this study, different groups of emerging contaminants were studied for decomposition efficiency using pilot-scale UV/H2O2 oxidation setup, including EDCs, PPCPs, taste and odor (T&O), and perfluorinated compounds. Results found that MP UV/H2O2 AOP was efficient in removing all the selected contaminants except perfluorinated compounds. Study of the kinetics of the process showed that both light absorption and quantum yield of each compound affected the decomposition performance. Analysis of water quality parameters of the treated water indicated that the outcome of both UV photolysis and UV/H2O2 processes can be affected by changes in the feed water quality.

  18. JRR-3 cold neutron source facility H2-O2 explosion safety proof testing

    International Nuclear Information System (INIS)

    Hibi, T.; Fuse, H.; Takahashi, H.; Akutsu, C.; Kumai, T.; Kawabata, Y.

    1990-01-01

    A cold Neutron Source (CNS) will be installed in Japan Research Reactor-3 (JRR-3) in Japan Atomic Energy Research Institute (JAERI) during its remodeling project. This CNS holds liquid hydrogen at a temperature of about 20 K as a cold neutron source moderator in the heavy water area of the reactor to moderate thermal neutrons from the reactor to cold neutrons of about 5 meV energy. In the hydrogen circuit of the CNS safety measures are taken to prevent oxygen/hydrogen reaction (H 2 -O 2 explosion). It is also designed in such manner that, should an H 2 -O 2 explosion take place, the soundness of all the components can be maintained so as not to harm the reactor safety. A test hydrogen circuit identical to that of the CNS (real components designed by TECHNICATOME of France) was manufactured to conduct the H 2 -O 2 explosion test. In this test, the detonation that is the severest phenomenon of the oxygen/hydrogen reaction took place in the test hydrogen circuit to measure the exerted pressure on the components and their strain, deformation, leakage, cracking, etc. Based on the results of this measurement, the structural strength of the test hydrogen circuit was analyzed. The results of this test show that the hydrogen circuit components have sufficient structural strength to withstand an oxygen/hydrogen reaction

  19. Carnosol promotes endothelial differentiation under H2O2-induced oxidative stress

    Directory of Open Access Journals (Sweden)

    Ou Shulin

    2017-01-01

    Full Text Available Oxidative stress causes deregulation of endothelial cell differentiation. Carnosol is a potent antioxidant and antiinflammatory compound. In the present study, we examined whether the antioxidant effect of carnosol might protect bone marrow stem cells against H2O2-induced oxidative stress and promote endothelial differentiation. We examined cell viability by the MTT assay; oxidative stress and apoptosis were analyzed through changes in ROS levels, apoptotic ratio and caspase-3 activity; changes in protein expression of OCT-4, Flk-1, CD31 and Nrf-2 were assessed by Western blot analysis. H2O2 treatment increased oxidative stress and reduced cell viability, while the stem cell marker OCT-4 and endothelial markers Flk-1, CD31 were significantly downregulated as a result of the treatment with H2O2. Treatment with carnosol improved the antioxidant status, increased OCT-4 expression and promoted endothelial differentiation. This study provides evidence that carnosol could increase the antioxidant defense mechanism and promote endothelial differentiation.

  20. Polydatin Attenuates H2O2-Induced Oxidative Stress via PKC Pathway

    Directory of Open Access Journals (Sweden)

    Huilian Qiao

    2016-01-01

    Full Text Available Oxidative stress plays an important role in the pathogenesis of endothelial dysfunction, which is found to precede the development of diverse cardiovascular diseases (CVDs. The aim of this study was to observe the protective effects of PD against H2O2-induced oxidative stress injury (OSI in human umbilical vein endothelial cells (HUVECs and the possible mechanism of PD in OSI treatment. HUVECs were subjected to H2O2 in the absence or presence of PD. It turned out that PD improved cell viability and adhesive and migratory abilities, inhibited the release of lactate dehydrogenase (LDH and reactive oxygen species (ROS, and elevated the content of glutathione peroxidase (GSH-Px and superoxide dismutase (SOD. TUNEL, fluorometric assays, and Western blotting showed that OSI upregulated the apoptosis ratio, the activity of caspase-3 and the level of proapoptotic protein Bax and decreased the level of antiapoptotic protein Bcl-2. However, PD treatment partially reversed these damage effects and Protein Kinase C (PKC activation by thymeleatoxin (THX in turn eliminated the antiapoptotic effect of PD. Furthermore, PD attenuated the H2O2-induced phosphorylation of PKCs α and δ and increased the phosphorylation of PKC ε. Our results indicated that PD might exert protective effects against OSI through various interactions with PKC pathway.

  1. Modulating and Measuring Intracellular H2O2 Using Genetically Encoded Tools to Study Its Toxicity to Human Cells.

    Science.gov (United States)

    Huang, Beijing K; Stein, Kassi T; Sikes, Hadley D

    2016-12-16

    Reactive oxygen species (ROS) such as H 2 O 2 play paradoxical roles in mammalian physiology. It is hypothesized that low, baseline levels of H 2 O 2 are necessary for growth and differentiation, while increased intracellular H 2 O 2 concentrations are associated with pathological phenotypes and genetic instability, eventually reaching a toxic threshold that causes cell death. However, the quantities of intracellular H 2 O 2 that lead to these different responses remain an unanswered question in the field. To address this question, we used genetically encoded constructs that both generate and quantify H 2 O 2 in a dose-response study of H 2 O 2 -mediated toxicity. We found that, rather than a simple concentration-response relationship, a combination of intracellular concentration and the cumulative metric of H 2 O 2 concentration multiplied by time (i.e., the area under the curve) determined the occurrence and level of cell death. Establishing the quantitative relationship between H 2 O 2 and cell toxicity promotes a deeper understanding of the intracellular effects of H 2 O 2 specifically as an individual reactive oxygen species, and it contributes to an understanding of its role in various redox-related diseases.

  2. H2O2 INDUCES APOPTOSIS OF RABBIT CHONDROCYTES VIA BOTH THE EXTRINSIC AND THE CASPASE-INDEPENDENT INTRINSIC PATHWAYS

    Directory of Open Access Journals (Sweden)

    CAIPING ZHUANG

    2013-07-01

    Full Text Available Osteoarthritis (OA, one of the most common joint diseases with unknown etiology, is characterized by the progressive destruction of articular cartilage and the apoptosis of chondrocytes. The purpose of this study is to elucidate the molecular mechanisms of H2O2-mediated rabbit chondrocytes apoptosis. CCK-8 assay showed that H2O2 treatment induced a remarkable reduction of cell viability, which was further verified by the remarkable phosphatidylserine externalization after H2O2 treatment for 1 h, the typical characteristics of apoptosis. H2O2 treatment induced a significant dysfunction of mitochondrial membrane potential (ΔΨm, but did not induce casapse-9 activation, indicating that H2O2 treatment induced caspase-independent intrinsic apoptosis that was further verified by the fact that silencing of AIF but not inhibiting caspase-9 potently prevented H2O2-induced apoptosis. H2O2 treatment induced a significant increase of caspase-8 and -3 activation, and inhibition of caspase-8 or -3 significantly prevented H2O2-induced apoptosis, suggesting that the extrinsic pathway played an important role. Collectively, our findings demonstrate that H2O2 induces apoptosis via both the casapse-8-mediated extrinsic and the caspase-independent intrinsic apoptosis pathways in rabbit chondrocytes.

  3. Demonstration test and evaluation of Ultraviolet/Ultraviolet Catalyzed Peroxide Oxidation for Groundwater Remediation at Oak Ridge K-25 Site

    International Nuclear Information System (INIS)

    1994-03-01

    We demonstrated, tested and evaluated a new ultraviolet (UV) lamp integrated with an existing commercial technology employing UV catalyzed peroxide oxidation to destroy organics in groundwater at an Oak Ridge K-25 site. The existing commercial technology is the perox-pure trademark process of Peroxidation Systems Incorporated (PSI) that employs standard UV lamp technology to catalyze H 2 O 2 into OH radicals, which attack many organic molecules. In comparison to classical technologies for remediation of groundwater contaminated with organics, the perox-pure trademark process not only is cost effective but also reduces contaminants to harmless by-products instead of transferring the contaminants from one medium to another. Although the perox-pure trademark process is cost effective against many organics, it is not effective for some organic contaminants of interest to DOE such as TCA, which has the highest concentration of the organics at the K-25 test site. Contaminants such as TCA are treated more readily by direct photolysis using short wavelength UV light. WJSA has been developing a unique UV lamp which is very efficient in the short UV wavelength region. Consequently, combining this UV lamp with the perox-pure trademark process results in a means for treating essentially all organic contaminants. In the program reported here, the new UV lamp lifetime was improved and the lamp integrated into a PSI demonstration trailer. Even though this UV lamp operated at less than optimum power and UV efficiency, the destruction rate for the highest concentration organic (TCA) was more than double that of the commercial unit. An optimized UV lamp may double again the destruction rate; i.e., a factor of four greater than the commercial system. The demonstration at K-25 included tests with (1) the commercial PSI system, (2) the new UV lamp-based system and (3) the commercial PSI and new UV lamp systems in series

  4. Biomimetic oxidation of carbamazepine with hydrogen peroxide catalyzed by a manganese porphyrin

    Directory of Open Access Journals (Sweden)

    Cláudia M. B. Neves

    2012-01-01

    Full Text Available This laboratory project is planned for an undergraduate chemistry laboratory in which students prepare a manganese porphyrin able to mimic the oxidative metabolism of carbamazepine, one of the most frequently prescribed drugs in the treatment of epilepsy. The in vitro oxidation of carbamazepine results in the formation of the corresponding 10,11-epoxide, the main in vivo metabolite. The reaction is catalyzed by manganese porphyrin in the presence of H2O2, an environmentally-friendly oxidant. Through this project students will develop their skills in organic synthesis, coordination chemistry, chromatographic techniques such as TLC and HPLC, UV-visible spectrophotometry, and NMR spectroscopy.

  5. Decapado de un acero inoxidable austenítico mediante mezclas ecológicas basadas en H2O2 - H2SO4 - iones F-

    Directory of Open Access Journals (Sweden)

    Narváez, L.

    2013-04-01

    Full Text Available This study reports the pickling of 316L stainless steel using mixtures of hydrogen peroxide (H2O2, sulphuric acid (H2SO4 and fluoride ions as hydrofluoric acid (HF, sodium fluoride (NaF and potassium fluoride (KF. The decomposition of H2O2 in the mixtures was assessed at different temperatures 25 °C to 60 °C, with ferric ion contents from 0 to 40 g/l. According to the results obtained, were established the optimal condition pickling at 20 g/l of ferric ions, 25 °C and p-toluensulphonic acid as stabilizer of H2O2. The HF pickling mixture was the only capable to remove totally the oxide layer from the 316L stainless steel after 300 s. The fluoride salts pickling mixtures only remove partially the oxide layer (20 to 40 % aprox. after 300 s. When the pickling time was increased until 1200 s, the removal percentages were around to 80 %.En este estudio se presenta el decapado del acero inoxidable austenítico 316L utilizando mezclas de peróxido de hidrógeno (H2O2/ácido sulfúrico (H2SO4/iones fluoruro; los iones fluoruro provienen del ácido fluorhídrico (HF, fluoruro de sodio (NaF y fluoruro de potasio (KF. La estabilidad del H2O2 fue valorada modificando las concentraciones del ión férrico de 0 a 40 g/l y las temperaturas de 25 °C a 60 °C en las mezclas decapantes. Se establecieron las condiciones óptimas de decapado utilizando 20 g/l de iones férrico a 25 °C empleando el ácido p-toluensulfónico como estabilizante del H2O2. La mezcla que contenía HF fue la única capaz de eliminar completamente los óxidos superficiales del acero a tiempos de 300 s. Las mezclas a base de sales fluoradas eliminaron parcialmente los óxidos (20 y 40 % aprox. en 300 s. Al incrementar el tiempo de decapado hasta 1200 s se obtuvieron porcentajes de eliminación alrededor de un 80 %.

  6. Kinetic removal of haloacetonitrile precursors by photo-based advanced oxidation processes (UV/H2O2, UV/O3, and UV/H2O2/O3).

    Science.gov (United States)

    Srithep, Sirinthip; Phattarapattamawong, Songkeart

    2017-06-01

    The objective of the study is to evaluate the performance of conventional treatment process (i.e., coagulation, flocculation, sedimentation and sand filtration) on the removals of haloacetonitrile (HAN) precursors. In addition, the removals of HAN precursors by photo-based advanced oxidation processes (Photo-AOPs) (i.e., UV/H 2 O 2 , UV/O 3 , and UV/H 2 O 2 /O 3 ) are investigated. The conventional treatment process was ineffective to remove HAN precursors. Among Photo-AOPs, the UV/H 2 O 2 /O 3 was the most effective process for removing HAN precursors, followed by UV/H 2 O 2 , and UV/O 3 , respectively. For 20min contact time, the UV/H 2 O 2 /O 3 , UV/H 2 O 2 , and UV/O 3 suppressed the HAN formations by 54, 42, and 27% reduction. Increasing ozone doses from 1 to 5 mgL -1 in UV/O 3 systems slightly improved the removals of HAN precursors. Changes in pH (6-8) were unaffected most of processes (i.e., UV, UV/H 2 O 2 , and UV/H 2 O 2 /O 3 ), except for the UV/O 3 system that its efficiency was low in the weak acid condition. The pseudo first-order kinetic constant for removals of dichloroacetonitrile precursors (k' DCANFP ) by the UV/H 2 O 2 /O 3 , UV/H 2 O 2 and standalone UV systems were 1.4-2.8 orders magnitude higher than the UV/O 3 process. The kinetic degradation of dissolved organic nitrogen (DON) tended to be higher than the k' DCANFP value. This study firstly differentiates the kinetic degradation between DON and HAN precursors. Copyright © 2017 Elsevier Ltd. All rights reserved.

  7. Inhibitory Effect of Dissolved Silica on the H2O2 Decomposition by Iron(III) and Manganese(IV) Oxides: Implications for H2O2-based In Situ Chemical Oxidation

    Science.gov (United States)

    Pham, Anh Le-Tuan; Doyle, Fiona M.; Sedlak, David L.

    2011-01-01

    The decomposition of H2O2 on iron minerals can generate •OH, a strong oxidant that can transform a wide range of contaminants. This reaction is critical to In Situ Chemical Oxidation (ISCO) processes used for soil and groundwater remediation, as well as advanced oxidation processes employed in waste treatment systems. The presence of dissolved silica at concentrations comparable to those encountered in natural waters decreases the reactivity of iron minerals toward H2O2, because silica adsorbs onto the surface of iron minerals and alters catalytic sites. At circumneutral pH values, goethite, amorphous iron oxide, hematite, iron-coated sand and montmorillonite that were pre-equilibrated with 0.05 – 1.5 mM SiO2 were significantly less reactive toward H2O2 decomposition than their original counterparts, with the H2O2 loss rates inversely proportional to the SiO2 concentration. In the goethite/H2O2 system, the overall •OH yield, defined as the percentage of decomposed H2O2 producing •OH, was almost halved in the presence of 1.5 mM SiO2. Dissolved SiO2 also slows the H2O2 decomposition on manganese(IV) oxide. The presence of dissolved SiO2 results in greater persistence of H2O2 in groundwater, lower H2O2 utilization efficiency and should be considered in the design of H2O2-based treatment systems. PMID:22129132

  8. Human low density lipoprotein (LDL) oxidation by metmyoglobin/H2O2: involvement of α-tocopheroxyl and phosphatidylcholine alkoxyl radicals

    International Nuclear Information System (INIS)

    Witting, P.K.; Willhite, C.A.; Stocker, R.; Davies, M.J.

    1998-01-01

    Full text: Metmyoglobin (metMb) and H 2 O 2 can oxidize low density lipoprotein (LDL) in vitro; formation of such oxidized LDL may be atherogenic. The role of α-tocopherol (α-TOH) in LDL oxidation by peroxidases, such as metMb is unclear. Herein we show that during metMb/H 2 O 2 -induced oxidation of native, α-TOH-containing, LDL, α-tocopheroxyl radical (α-TO) and hydroperoxides and hydroxides of cholesteryl esters (CE-O(O)H) and phosphatidylcholine (PC-O(O)H) accumulated concomitantly with α-TOH consumption. Accumulation of CE-O(O)H was dependent on, and correlated with, LDL's α-TOH content indicating that α-TO . acted as a chain-transfer agent and propagated LDL lipid peroxidation via tocopherol-mediated peroxidation (TMP). Further, the ratio of accumulating CE-O(O)H to PC-O(O)H remained constant in the presence α-TOH. Subsequent to α-TOH depletion, CE-O(O)H continued to accumulate, albeit at a lower rate than in the presence of α-TOH. This was accompanied by depletion of PC-OOH, a rapid increase in the CE-O(O)H/PC-O(O)H ratio, formation of lipid-derived alkoxyl radicals and phosphatidylcholine hydroxides (PC-OH), and accumulation of a second organic radical, characterized by a broad singlet EPR signal. The latter persisted for several hours at 37 deg C. We conclude that metMb/H 2 O 2 -induced peroxidation of LDL lipids is not inhibited by α-TOH and occurs initially via TMP. After α-TOH depletion, cholesteryl esters peroxidize at higher fractional rates than surface phospholipids, and this appears to be mediated via reactions involving alkoxyl radicals derived from the peroxidatic activity of metMb on PC-OO

  9. Toward in vivo detection of hydrogen peroxide with ultrasound molecular imaging

    Science.gov (United States)

    Olson, Emilia S.; Orozco, Jahir; Wu, Zhe; Malone, Christopher D.; Yi, Boemha; Gao, Wei; Eghtedari, Mohammad; Wang, Joseph; Mattrey, Robert F.

    2013-01-01

    We present a new class of ultrasound molecular imaging agents that extend upon the design of micromotors that are designed to move through fluids by catalyzing hydrogen peroxide (H2O2) and propelling forward by escaping oxygen microbubbles. Micromotor converters require 62 mm of H2O2 to move – 1000-fold higher than is expected in vivo. Here, we aim to prove that ultrasound can detect the expelled microbubbles, to determine the minimum H2O2 concentration needed for microbubble detection, explore alternate designs to detect the H2O2 produced by activated neutrophils and perform preliminary in vivo testing. Oxygen microbubbles were detected by ultrasound at 2.5 mm H2O2. Best results were achieved with a 400–500 nm spherical design with alternating surface coatings of catalase and PSS over a silica core. The lowest detection limit of 10–100 µm was achieved when assays were done in plasma. Using this design, we detected the H2O2 produced by freshly isolated PMA-activated neutrophils allowing their distinction from naïve neutrophils. Finally, we were also able to show that direct injection of these nanospheres into an abscess in vivo enhanced ultrasound signal only when they contained catalase, and only when injected into an abscess, likely because of the elevated levels of H2O2 produced by inflammatory mediators. PMID:23958028

  10. Kinetics and Efficiency of H2O2 Activation by Iron-Containing Minerals and Aquifer Materials

    Science.gov (United States)

    Pham, Anh Le-Tuan; Doyle, Fiona M.; Sedlak, David L.

    2014-01-01

    To gain insight into factors that control H2O2 persistence and ˙OH yield in H2O2-based in situ chemical oxidation systems, the decomposition of H2O2 and transformation of phenol were investigated in the presence of iron-containing minerals and aquifer materials. Under conditions expected during remediation of soil and groundwater, the stoichiometric efficiency, defined as the amount of phenol transformed per mole of H2O2 decomposed, varied from 0.005 to 0.28%. Among the iron-containing minerals, iron oxides were 2 to 10 times less efficient in transforming phenol than iron-containing clays and synthetic iron-containing catalysts. In both iron-containing mineral and aquifer materials systems, the stoichiometric efficiency was inversely correlated with the rate of H2O2 decomposition. In aquifer materials systems, the stoichiometric efficiency was also inversely correlated with the Mn content, consistent with the fact that the decomposition of H2O2 on manganese oxides does not produce ˙OH. Removal of iron and manganese oxide coatings from the surface of aquifer materials by extraction with citrate-bicarbonate-dithionite slowed the rate of H2O2 decomposition on aquifer materials and increased the stoichiometric efficiency. In addition, the presence of 2 mM of dissolved SiO2 slowed the rate of H2O2 decomposition on aquifer materials by over 80% without affecting the stoichiometric efficiency. PMID:23047055

  11. Structure of H2/O2/N2 flames at atmospheric pressure studied by molecular beam mass spectrometry and modeling

    NARCIS (Netherlands)

    Knyazkov, D.A.; Korobeinichev, O.P.; Shmakov, A.G.; Rybitskaya, I.V.; Bolshova, T.A.; Chernov, D.A.; Konnov, A.A.

    2009-01-01

    Structure of laminar premixed flat H2/O2/N2 flames with different equivalence ratios at atmospheric pressure isinvestigated experimentally and by numerical modeling. Concentration profiles of stable species (H2, O2, H2O) as well as of H atoms and OH radicals in the flames were measured using

  12. The effect of MWCNT treatment by H2O2 and/or UV on fulvic acids sorption.

    Science.gov (United States)

    Czech, Bożena

    2017-05-01

    The carbon nanotubes (CNT) present in the wastewater subjected to treatment will possess altered physico-chemical properties. The changed properties will result in the unknown behavior of CNT in the environment after disposal; and it is expected to differ from their pristine analogues. In the present paper the effect of sorption of dissolved organic matter with fulvic acids (FA) as representatives onto UV and/or H 2 O 2 treated CNT was tested. Both kinetics and mechanism of sorption was estimated. The chemical adsorption was a rate limiting step and a pseudo-second order kinetics described the sorption of FA onto UV and/or H 2 O 2 treated CNT. The treating increased affinity towards FA and treating by UV and H 2 O 2 simultaneously possessed greater impact on k 2 than UV and H 2 O 2 separately. The greatest effect on CNT sorption capacity revealed H 2 O 2 . The sorption mechanism was described by Temkin (CNT-H 2 O 2 ) and Dubinin-Radushkevich model. The increase in CNT surface disorder caused by UV and/or H 2 O 2 treatment favored sorption of FA via π-π interactions (exfoliated surface and disordered CNT walls). FA sorption occurred between aromatic rings of FA and CNT and hydrogen bonds formed with the oxygen functional groups. The results indicate that UV and/or H 2 O 2 treatment affected the sorption capacity and affinity of CNT towards FA. Copyright © 2017 Elsevier Inc. All rights reserved.

  13. Effect of residual H2O2 from advanced oxidation processes on subsequent biological water treatmen : A laboratory batch study

    NARCIS (Netherlands)

    Wang, F.; van Halem, D.; Liu, G.; Lekkerkerker-Teunissen, K.; van der Hoek, J.P.

    2017-01-01

    H2O2 residuals from advanced oxidation processes (AOPs) may have critical impacts on the microbial ecology and performance of subsequent biological treatment processes, but little is known. The objective of this study was to evaluate how H2O2 residuals influence sand systems with an emphasis on

  14. Enhanced poly(γ-glutamic acid) production by H2 O2 -induced reactive oxygen species in the fermentation of Bacillus subtilis NX-2.

    Science.gov (United States)

    Tang, Bao; Zhang, Dan; Li, Sha; Xu, Zongqi; Feng, Xiaohai; Xu, Hong

    2016-09-01

    Effects of reactive oxygen species (ROS) on cell growth and poly(γ-glutamic acid) (γ-PGA) synthesis were studied by adding hydrogen peroxide to a medium of Bacillus subtilis NX-2. After optimizing the addition concentration and time of H 2 O 2 , a maximum concentration of 33.9 g/L γ-PGA was obtained by adding 100 µM H 2 O 2 to the medium after 24 H. This concentration was 20.6% higher than that of the control. The addition of diphenyleneiodonium chloride (ROS inhibitor) can interdict the effect of H 2 O 2 -induced ROS. Transcriptional levels of the cofactors and relevant genes were also determined under ROS stress to illustrate the possible metabolic mechanism contributing to the improve γ-PGA production. The transcriptional levels of genes belonging to the tricarboxylic acid cycle and electron transfer chain system were significantly increased by ROS, which decreased the NADH/NAD + ratio and increased the ATP levels, thereby providing more reducing power and energy for γ-PGA biosynthesis. The enhanced γ-PGA synthetic genes also directly promoted the formation of γ-PGA. This study was the first to use the ROS control strategy for γ-PGA fermentation and provided valuable information on the possible mechanism by which ROS regulated γ-PGA biosynthesis in B. subtilis NX-2. © 2015 International Union of Biochemistry and Molecular Biology, Inc.

  15. Compromised Photosynthetic Electron Flow And H2O2 Generation Correlate with Genotype-Specific Stomatal Dysfunctions During Resistance Against Powdery Mildew In Oats.

    Directory of Open Access Journals (Sweden)

    Javier Sánchez-Martín

    2016-11-01

    Full Text Available Stomatal dysfunction known as locking has been linked to the elicitation of a hypersensitive response (HR following attack of fungal pathogens in cereals. We here assess how spatial and temporal patterns of different resistance mechanisms, such as HR and penetration resistance influence stomatal and photosynthetic parameters in oat (Avena sativa and the possible involvement of hydrogen peroxide (H2O2 in the dysfunctions observed. Four oat cultivars with differential resistance responses (i.e. penetration resistance, early and late HR to powdery mildew (Blumeria graminis f. sp. avenae, Bga were used. Results demonstrated that stomatal dysfunctions were genotype but not response-type dependent since genotypes with similar resistance responses when assessed histologically showed very different locking patterns. Maximum quantum yield (Fv/Fm of photosystem II were compromised in most Bga–oat interactions and photoinhibition increased. However, the extent of the photosynthetic alterations was not directly related to the extent of HR. H2O2 generation is triggered during the execution of resistance responses and can influence stomatal function. Artificially increasing H2O2 by exposing plants to increased light intensity further reduced Fv/Fm ratios and augmented the patterns of stomatal dysfunctions previously observed. The latter results suggest that the observed dysfunctions and hence a cost of resistance may be linked with oxidative stress occurring during defence induced photosynthetic disruption.

  16. A polysaccharide of Dendrobium officinale ameliorates H2O2-induced apoptosis in H9c2 cardiomyocytes via PI3K/AKT and MAPK pathways.

    Science.gov (United States)

    Zhang, Jing-Yi; Guo, Ying; Si, Jin-Ping; Sun, Xiao-Bo; Sun, Gui-Bo; Liu, Jing-Jing

    2017-11-01

    Dendrobium officinale is one valuable traditional Chinese medicine, which has skyscraping medicinal value. Polysaccharide is the main active ingredient in D. officinale; its antioxidant activity is a hot research topic nowadays. Oxidative stress plays an important role in the pathological progress of a variety of cardiovascular disease, as one of key factors of cardiomyocyte apoptosis. This research adopts a model of H 2 O 2 induction-H9c2 cardiomyocytes apoptosis, aiming to study the effect of Dendrobium officinale Polysaccharide (DOP-GY) for cardiomyocyte apoptosis caused by oxidative stress and its possible mechanism. Our results showed that pretreatment of DOP-GY (low dose: 6.25μg/mL, medium dose: 12.5μg/mL, high dose: 25μg/mL) followed by a 2h incubation with 200μM H 2 O 2 elevated the survival rate, cutted the LDH leakage, reduced lipid peroxidation damage, improved the activity of the endogenous antioxidant enzymes. In addition, the pretreatment of DOP-GY significantly inhibited the production of ROS, declined of the mitochondrial membrane potential, down-regulated pro-apoptosis protein and up-regulated anti-apoptosis protein. The protective effect was correlated with the PI3K/Akt and MAPK signal pathway. Collectively, these observations suggest that DOY-GY has the potential to exert cardioprotective effects against H 2 O 2 -induced H9c2 cardiomyocyte apoptosis. Copyright © 2017 Elsevier B.V. All rights reserved.

  17. A unique polysaccharide purified from Hericium erinaceus mycelium prevents oxidative stress induced by H2O2 in human gastric mucosa epithelium cell.

    Science.gov (United States)

    Wang, Mingxing; Kanako, Nakajima; Zhang, Yanqiu; Xiao, Xulang; Gao, Qipin; Tetsuya, Konishi

    2017-01-01

    Hericium erinaceus (HE) has been used both as a traditional Chinese medicine and home remedy for treatment of gastric and duodenal ulcers and gastritis. EP-1, a purified polysaccharide isolated from HE mycelium, has recently been identified as the active component responsible for HE anti-gastritis activity. Because oxidative stress has been implicated as a pathogenic cause of gastritis and gastric ulcers, EP-1 antioxidant properties were systematically examined in vitro using the human gastric mucosal epithelial cell line, GES-1. Results showed that EP-1 possessed higher oxygen radical absorbance capacity (ORAC) and 2-3 times higher ability to scavenge 2,2-diphenyl-1-picrylhydrazyl (DPPH), superoxide and hydroxyl radicals than a hot water extract of commercially available HE fruiting body. A crude mycelial polysaccharide (CMPS) extract of HE, from which EP-1 was purified, showed slightly stronger radical scavenging activity and ORAC than EP-1, with the exception of DPPH-scavenging activity. Antioxidant activities of these extracts were further studied using hydrogen peroxide (H2O2)-abused GES-1 cells; EP-1 dose-dependently preserved cell viability of abused cells as assessed via MTT assay. Moreover, FACS analysis revealed that EP-1 prevented H2O2-induced apoptotic cell death by inhibiting activation of apoptotic cellular signals within mitochondria-dependent apoptotic pathways. CMPS also prevented H2O2-induced oxidative stress, but to a lesser degree than did EP-1, even though CMPS exhibited comparable or stronger in vitro antioxidant activity than did EP-1.

  18. Flower-like Bi2Se3 nanostructures: Synthesis and their application for the direct electrochemistry of hemoglobin and H2O2 detection

    International Nuclear Information System (INIS)

    Fan Hai; Zhang Shenxiang; Ju Peng; Su Haichao; Ai Shiyun

    2012-01-01

    Highlights: ► Flower-like Bi 2 Se 3 nanostructures were prepared via a hydrothermal technique. ► Bi 2 Se 3 nanostructures significantly improve the direct electron-transfer of Hb. ► The immobilized Hb shows high catalytic activity to the reduction of H 2 O 2 . - Abstract: In this paper, flower-like Bi 2 Se 3 nanostructures consisting of intercrossed nanosheets networks have been synthesized via a facile hydrothermal technique and applied to the protein electrochemistry for the first time. The prepared Bi 2 Se 3 nanostructures were characterized by X-ray diffraction (XRD), scanning electron microscope (SEM) and transmission electron microscopy (TEM). The direct electrochemistry of hemoglobin (Hb) has been achieved by immobilizing Hb on the prepared Bi 2 Se 3 nanostructures and Nafion (Nf) modified glassy carbon electrode. Bi 2 Se 3 nanostructures show significant promotion to the direct electron-transfer of Hb. The immobilized Hb retained its biological activity well and shows high catalytic activity to the reduction of hydrogen peroxide (H 2 O 2 ). Under the optimal experimental conditions, the catalytic currents are linear to the concentrations of H 2 O 2 in the range of 2.0 × 10 −6 to 1.0 × 10 −4 M. The corresponding detection limits are 6.3 × 10 −7 M. The prepared flower-like Bi 2 Se 3 nanostructures provide an alternative matrix for protein immobilization and biosensor preparation.

  19. Oxygen Reduction Reaction for Generating H2 O2 through a Piezo-Catalytic Process over Bismuth Oxychloride.

    Science.gov (United States)

    Shao, Dengkui; Zhang, Ling; Sun, Songmei; Wang, Wenzhong

    2018-02-09

    Oxygen reduction reaction (ORR) for generating H 2 O 2 through green pathways have gained much attention in recent years. Herein, we introduce a piezo-catalytic approach to obtain H 2 O 2 over bismuth oxychloride (BiOCl) through an ORR pathway. The piezoelectric response of BiOCl was directly characterized by piezoresponse force microscopy (PFM). The BiOCl exhibits efficient catalytic performance for generating H 2 O 2 (28 μmol h -1 ) only from O 2 and H 2 O, which is above the average level of H 2 O 2 produced by solar-to-chemical processes. A piezo-catalytic mechanism was proposed: with ultrasonic waves, an alternating electric field will be generated over BiOCl, which can drive charge carriers (electrons) to interact with O 2 and H 2 O, then to form H 2 O 2 . © 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  20. Nanoporous graphene obtained by hydrothermal process in H2O2 and its application for supercapacitors

    Science.gov (United States)

    Lv, Jinlong; Liang, Tongxiang

    2016-08-01

    Nanohole graphene oxide (NHGO) was obtained in a homogeneous aqueous mixture of graphene oxide (GO) and H2O2 at 120 °C. Supercapacitors were fabricated as the electrode material by using NHGO. A specific capacitance of 240.1 F g-1 was obtained at a current density of 1 A g-1 in 6 m KOH electrolyte and specific capacitance remained 193.6 F g-1 at the current density of 20 A g-1. This was attributed to reducing the inner space between the double-layers, enhanced ion diffusion and large specific surface area. Supercapacitor prepared with NHGO electrodes also exhibited an excellent cycle stability.

  1. Synthesis of Poly aniline-Montmorillonite Nano composites Using H2O2 as the Oxidant

    International Nuclear Information System (INIS)

    Binitha, N.; Binitha, N.; Suraja, V.; Zahira Yaakob; Sugunan, S.

    2011-01-01

    Poly aniline montmorillonite nano composite was prepared using H 2 O 2 as the oxidant. The catalytic environment of montmorillonite favours polymerization. Intercalation and composite formation was proven from various techniques such as XRD, FTIR, DRS and thermal analysis. XRD patterns give the dimension of the intercalated PANI, from the shift of 2θ values, which is in the nano range. FTIR showed that PANI composite formation occurred without affecting the basic clay layer structure. Thus the successful development of an alternative cheap route for poly aniline-montmorillonite nano composite was well established. (author)

  2. Oxyhydroxide of metallic nanowires in a molecular H2O and H2O2 environment and their effects on mechanical properties.

    Science.gov (United States)

    Aral, Gurcan; Islam, Md Mahbubul; Wang, Yun-Jiang; Ogata, Shigenobu; Duin, Adri C T van

    2018-06-14

    To avoid unexpected environmental mechanical failure, there is a strong need to fully understand the details of the oxidation process and intrinsic mechanical properties of reactive metallic iron (Fe) nanowires (NWs) under various aqueous reactive environmental conditions. Herein, we employed ReaxFF reactive molecular dynamics (MD) simulations to elucidate the oxidation of Fe NWs exposed to molecular water (H2O) and hydrogen peroxide (H2O2) environment, and the influence of the oxide shell layer on the tensile mechanical deformation properties of Fe NWs. Our structural analysis shows that oxidation of Fe NWs occurs with the formation of different iron oxide and hydroxide phases in the aqueous molecular H2O and H2O2 oxidizing environments. We observe that the resulting microstructure due to pre-oxide shell layer formation reduces the mechanical stress via increasing the initial defect sites in the vicinity of the oxide region to facilitate the onset of plastic deformation during tensile loading. Specifically, the oxide layer of Fe NWs formed in the H2O2 environment has a relatively significant effect on the deterioration of the mechanical properties of Fe NWs. The weakening of the yield stress and Young modulus of H2O2 oxidized Fe NWs indicates the important role of local oxide microstructures on mechanical deformation properties of individual Fe NWs. Notably, deformation twinning is found as the primary mechanical plastic deformation mechanism of all Fe NWs, but it is initially observed at low strain and stress level for the oxidized Fe NWs.

  3. Selective electronalysis of peracetic acid in the presence of a large excess of H2O2 at Au(1 1 1)-like gold electrode

    International Nuclear Information System (INIS)

    Awad, M.I.

    2012-01-01

    Highlights: ► Analysis of peracetic acid in the presence of a large excess of H 2 O 2 is introduced. ► Au(1 1 1)-like gold electrode serves as an ideal for this purpose. ► The analysis is characterized by high selectivity and sensitivity. - Abstract: Peracetic acid (PAA) has been selectively electroanalyzed in the presence of a large excess of hydrogen peroxide (H 2 O 2 ), about 500 fold that of PAA, using Au (1 1 1)-like gold electrode in acetate buffer solutions of pH 5.4. Au(1 1 1)-like gold electrode was prepared by a controlled reductive desorption of a previously assembled thiol, typically cysteine, monolayer onto the polycrystalline gold (poly-Au) electrode. Cysteine molecules were selectively removed from the Au(1 1 1) facets of the poly-Au electrode, keeping the other two facets (i.e., Au(1 1 0) and Au(1 0 0)) under the protection of the adsorbed cysteine. It has been found that Au(1 1 1)-like gold electrode positively shifts the reduction peak of PAA, while, fortunately, shifts the reduction peak of H 2 O 2 negatively, achieving a large potential separation (around 750 mV) between the two reduction peaks as compared with that (around 450 mV) obtained at the poly-Au electrode. This large potential separation between the two reduction peaks enabled the analysis of PAA in the presence of a large excess of H 2 O 2 . In addition, the positive shift of the reduction peak of PAA gives the present method a high immunity against the interference of the dissolved oxygen.

  4. Facile synthesis technology of Li_3V_2(PO_4)_3/C adding H_2O_2 in ball mill process

    International Nuclear Information System (INIS)

    Min, Xiujuan; Mu, Deying; Li, Ruhong; Dai, Changsong

    2016-01-01

    Highlights: • Sintering time of Li_3V_2(PO_4)_3 reduced to 6 hours by adding hydrogen peroxide. • Electrochemical performance of Li_3V_2(PO_4)_3 was improved by reducing sintering time. • The Li_3V_2(PO_4)_3 production process was simplified during material synthesis stage. - Abstract: Li_3V_2(PO_4)_3/C has stable structure, high theory specific capacity and good safety performance, therefore it has become the research focus of lithium-ion batteries in recent years. The facile synthesis technology of Li_3V_2(PO_4)_3/C was characterized by adding different amounts of H_2O_2. Structure and morphology characteristics were examined by XRD, TG, Raman Spectroscopy, XPS and SEM. Electrochemical performance was investigated by constant current charging and discharging test. The results revealed that the Li_3V_2(PO_4)_3/C electrochemical performance of adding 15 mL H_2O_2 was better after sintering during 6 h. At the charge cut-off voltage of 4.3 V, the first discharge capacity at 0.2 C rate reached 127 mAh g"−"1. Because of adding H_2O_2 in the ball-mill dispersant, the vanadium pentoxide formed the wet sol. The molecular-leveled mixture increased the homogeneity of raw materials. Therefore, the addition of H_2O_2 shortened the sintering time and significantly improved the electrochemical performance of Li_3V_2(PO_4)_3/C.

  5. Honeybee glucose oxidase—its expression in honeybee workers and comparative analyses of its content and H2O2-mediated antibacterial activity in natural honeys

    Science.gov (United States)

    Bucekova, Marcela; Valachova, Ivana; Kohutova, Lenka; Prochazka, Emanuel; Klaudiny, Jaroslav; Majtan, Juraj

    2014-08-01

    Antibacterial properties of honey largely depend on the accumulation of hydrogen peroxide (H2O2), which is generated by glucose oxidase (GOX)-mediated conversion of glucose in diluted honey. However, honeys exhibit considerable variation in their antibacterial activity. Therefore, the aim of the study was to identify the mechanism behind the variation in this activity and in the H2O2 content in honeys associated with the role of GOX in this process. Immunoblots and in situ hybridization analyses demonstrated that gox is solely expressed in the hypopharyngeal glands of worker bees performing various tasks and not in other glands or tissues. Real-time PCR with reference genes selected for worker heads shows that the gox expression progressively increases with ageing of the youngest bees and nurses and reached the highest values in processor bees. Immunoblot analysis of honey samples revealed that GOX is a regular honey component but its content significantly varied among honeys. Neither botanical source nor geographical origin of honeys affected the level of GOX suggesting that some other factors such as honeybee nutrition and/or genetic/epigenetic factors may take part in the observed variation. A strong correlation was found between the content of GOX and the level of generated H2O2 in honeys except honeydew honeys. Total antibacterial activity of most honey samples against Pseudomonas aeruginosa isolate significantly correlated with the H2O2 content. These results demonstrate that the level of GOX can significantly affect the total antibacterial activity of honey. They also support an idea that breeding of novel honeybee lines expressing higher amounts of GOX could help to increase the antibacterial efficacy of the hypopharyngeal gland secretion that could have positive influence on a resistance of colonies against bacterial pathogens.

  6. Descent Without Modification? The Thermal Chemistry of H2O2 on Europa and Other Icy Worlds

    Science.gov (United States)

    Loeffler, Mark Josiah; Hudson, Reggie Lester

    2015-01-01

    The strong oxidant H2O2 is known to exist in solid form on Europa and is suspected to exist on several other Solar System worlds at temperatures below 200 K. However, little is known of the thermal chemistry that H2O2 might induce under these conditions. Here, we report new laboratory results on the reactivity of solid H2O2 with eight different compounds in H2O-rich ices. Using infrared spectroscopy, we monitored compositional changes in ice mixtures during warming. The compounds CH4 (methane), C3H4 (propyne), CH3OH (methanol), and CH3CN (acetonitrile) were unaltered by the presence of H2O2 in ices, showing that exposure to either solid H2O2 or frozen H2O+H2O2 at cryogenic temperatures will not oxidize these organics, much less convert them to CO2. This contrasts strongly with the much greater reactivity of organics with H2O2 at higher temperatures, and particularly in the liquid and gas phases. Of the four inorganic compounds studied, CO, H2S, NH3, and SO2, only the last two reacted in ices containing H2O2, NH3 making NHþ 4 and SO2 making SO2 4 by H+ and e - transfer, respectively. An important astrobiological conclusion is that formation of surface H2O2 on Europa and that molecule's downward movement with H2O-ice do not necessarily mean that all organics encountered in icy subsurface regions will be destroyed by H2O2 oxidation.

  7. H2O2-responsive liposomal nanoprobe for photoacoustic inflammation imaging and tumor theranostics via in vivo chromogenic assay.

    Science.gov (United States)

    Chen, Qian; Liang, Chao; Sun, Xiaoqi; Chen, Jiawen; Yang, Zhijuan; Zhao, He; Feng, Liangzhu; Liu, Zhuang

    2017-05-23

    Abnormal H 2 O 2 levels are closely related to many diseases, including inflammation and cancers. Herein, we simultaneously load HRP and its substrate, 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS), into liposomal nanoparticles, obtaining a Lipo@HRP&ABTS optical nanoprobe for in vivo H 2 O 2 -responsive chromogenic assay with great specificity and sensitivity. In the presence of H 2 O 2 , colorless ABTS would be converted by HRP into the oxidized form with strong near-infrared (NIR) absorbance, enabling photoacoustic detection of H 2 O 2 down to submicromolar concentrations. Using Lipo@HRP&ABTS as an H 2 O 2 -responsive nanoprobe, we could accurately detect the inflammation processes induced by LPS or bacterial infection in which H 2 O 2 is generated. Meanwhile, upon systemic administration of this nanoprobe we realize in vivo photoacoustic imaging of small s.c. tumors (∼2 mm in size) as well as orthotopic brain gliomas, by detecting H 2 O 2 produced by tumor cells. Interestingly, local injection of Lipo@HRP&ABTS further enables differentiation of metastatic lymph nodes from those nonmetastatic ones, based on their difference in H 2 O 2 contents. Moreover, using the H 2 O 2 -dependent strong NIR absorbance of Lipo@HRP&ABTS, tumor-specific photothermal therapy is also achieved. This work thus develops a sensitive H 2 O 2 -responsive optical nanoprobe useful not only for in vivo detection of inflammation but also for tumor-specific theranostic applications.

  8. Progesterone amplifies oxidative stress signal and promotes NO production via H2O2 in mouse kidney arterial endothelial cells.

    Science.gov (United States)

    Yuan, Xiao-Hua; Fan, Yang-Yang; Yang, Chun-Rong; Gao, Xiao-Rui; Zhang, Li-Li; Hu, Ying; Wang, Ya-Qin; Jun, Hu

    2016-01-01

    The role of progesterone on the cardiovascular system is controversial. Our present research is to specify the effect of progesterone on arterial endothelial cells in response to oxidative stress. Our result showed that H2O2 (150 μM and 300 μM) induced cellular antioxidant response. Glutathione (GSH) production and the activity of Glutathione peroxidase (GPx) were increased in H2O2-treated group. The expression of glutamate cysteine ligase catalytic subunit (GCLC) and modifier subunit (GCLM) was induced in response to H2O2. However, progesterone absolutely abolished the antioxidant response through increasing ROS level, inhibiting the activity of Glutathione peroxidase (GPx), decreasing GSH level and reducing expression of GClC and GCLM. In our study, H2O2 induced nitrogen monoxide (NO) production and endothelial nitric oxide synthase (eNOS) expression, and progesterone promoted H2O2-induced NO production. Progesterone increased H2O2-induced expression of hypoxia inducible factor-α (HIFα) which in turn regulated eNOS expression and NO synthesis. Further study demonstrated that progesterone increased H2O2 concentration of culture medium which may contribute to NO synthesis. Exogenous GSH decreased the content of H2O2 of culture medium pretreated by progesterone combined with H2O2 or progesterone alone. GSH also inhibited expression of HIFα and eNOS, and abolished NO synthesis. Collectively, our study demonstrated for the first time that progesterone inhibited cellular antioxidant effect and increased oxidative stress, promoted NO production of arterial endothelial cells, which may be due to the increasing H2O2 concentration and amplified oxidative stress signal. Copyright © 2015. Published by Elsevier Ltd.

  9. Direct Synthesis of H2O2 over Ti-Containing Molecular Sieves Supported Gold Catalysts: A Comparative Study for In-situ-H2O2-ODS of Fuel

    International Nuclear Information System (INIS)

    Zhang, Han; Song, Haiyan; Chen, Chunxia; Han, Fuqin; Hu, Shaozheng; Liu, Guangliang; Chen, Ping; Zhao, Zhixi

    2013-01-01

    Direct synthesis of H 2 O 2 and in situ oxidative desulfurization of model fuel over Au/Ti-HMS and Au/TS-1 catalysts has been comparatively investigated in water or methanol. Maximum amount (82%) of active Au 0 species for H 2 O 2 synthesis was obtained. Au/Ti-HMS and Au/TS-1 exhibited the contrary performances in H 2 O 2 synthesis as CH 3 OH/H 2 O ratio of solvent changed. H 2 O 2 decomposition and hydrogenation in water was inhibited by the introduction of methanol. Effect of O 2 /H 2 ratio on H 2 O 2 concentration, H 2 conversion and H 2 O 2 selectivity revealed a relationship between H 2 O 2 generation and H2 consumption. The highest dibenzothiophene removal rate (83.2%) was obtained over Au/Ti-HMS in methanol at 1.5 of O 2 /H 2 ratio and 60 .deg. C. But removal of thiophene over Au/TS-1 should be performed in water without heating to obtain a high removal rate (61.3%). Meanwhile, H 2 conversion and oxidative desulfurization selectivity of H 2 were presented

  10. Modulation of notch signaling pathway to prevent H2O2/menadione-induced SK-N-MC cells death by EUK134.

    Science.gov (United States)

    Kamarehei, Maryam; Yazdanparast, Razieh

    2014-10-01

    The brain in Alzheimer's disease is under increased oxidative stress, and this may have a role in the pathogenesis and neural death in this disorder. It has been verified that numerous signaling pathways involved in neurodegenerative disorders are activated in response to reactive oxygen species (ROS). EUK134, a synthetic salen-manganese antioxidant complex, has been found to possess many interesting pharmacological activities awaiting exploration. The present study is to characterize the role of Notch signaling in apoptotic cell death of SK-N-MC cells. The cells were treated with hydrogen peroxide (H2O2) or menadione to induce oxidative stress. The free-radical scavenging capabilities of EUK134 were studied through the MTT assay, glutathione peroxidase (GPx) enzyme activity assay, and glutathione (GSH) Levels. The extents of lipid peroxidation, protein carbonyl formation, and intracellular ROS levels, as markers of oxidative stress, were also studied. Our results showed that H2O2/menadione reduced GSH levels and GPx activity. However, EUK134 protected cells against ROS-induced cell death by down-regulation of lipid peroxidation and protein carbonyl formation as well as restoration of antioxidant enzymes activity. ROS induced apoptosis and increased NICD and HES1 expression. Inhibition of NICD production proved that Notch signaling is involved in apoptosis through p53 activation. Moreover, H2O2/menadione led to Numb protein down-regulation which upon EUK134 pretreatment, its level increased and subsequently prevented Notch pathway activation. We indicated that EUK134 can be a promising candidate in designing natural-based drugs for ROS-induced neurodegenerative diseases. Collectively, ROS activated Notch signaling in SK-N-MC cells leading to cell apoptosis.

  11. Garlic and H2O2 in overcoming dormancy on the vine “Cabernet Sauvignon”

    Directory of Open Access Journals (Sweden)

    Saavedra del Aguila Juan

    2015-01-01

    Full Text Available The objective of this experiment was to evaluate the effect of garlic extract, H2O2 and hydrogen cyanamide on dormancy break, budding and maturation of “Cabernet Sauvignon” in the Campaign Region – Brazil. In late winter 2014 and after drought pruning were performed spraying in the bud: T1 – distilled water (control; T2 – 3.0% of hydrogen cyanamide; T3 – 18.0% H2O2; and T4 – 3.0% garlic extract. It was evaluated in the field: the number of sprouted buds per plant, number of bunches per plant and weight of bunches per plant; and laboratory: on ripening, performed weekly from the color change of 360 berries per treatment for analyzes solids soluble – SS (Brix pH and titratable acidity – TA (% tartaric acid. It was observed that the vines of treatment T4 (3.0% garlic extract, showed higher percentage of buds sprouting (63 shoots plant−1. Already at the number of clusters and weight per plant, there were no statistical differences between all treatments. The results obtained in the laboratory to SS, pH and TA did not differ statistically for the four tested treatments.

  12. Prediction of absolute infrared intensities for the fundamental vibrations of H2O2

    Science.gov (United States)

    Rogers, J. D.; Hillman, J. J.

    1981-01-01

    Absolute infrared intensities are predicted for the vibrational bands of gas-phase H2O2 by the use of a hydrogen atomic polar tensor transferred from the hydroxyl hydrogen atom of CH3OH. These predicted intensities are compared with intensities predicted by the use of a hydrogen atomic polar tensor transferred from H2O. The predicted relative intensities agree well with published spectra of gas-phase H2O2, and the predicted absolute intensities are expected to be accurate to within at least a factor of two. Among the vibrational degrees of freedom, the antisymmetric O-H bending mode nu(6) is found to be the strongest with a calculated intensity of 60.5 km/mole. The torsional band, a consequence of hindered rotation, is found to be the most intense fundamental with a predicted intensity of 120 km/mole. These results are compared with the recent absolute intensity determinations for the nu(6) band.

  13. Adiabatic burning velocity of H2-O2 mixtures diluted with CO2/N2/Ar

    International Nuclear Information System (INIS)

    Ratna Kishore, V.; Muchahary, Ringkhang; Ray, Anjan; Ravi, M.R.

    2009-01-01

    Global warming due to CO 2 emissions has led to the projection of hydrogen as an important fuel for future. A lot of research has been going on to design combustion appliances for hydrogen as fuel. This has necessitated fundamental research on combustion characteristics of hydrogen fuel. In this work, a combination of experiments and computational simulations was employed to study the effects of diluents (CO 2 , N 2 , and Ar) on the laminar burning velocity of premixed hydrogen/oxygen flames using the heat flux method. The experiments were conducted to measure laminar burning velocity for a range of equivalence ratios at atmospheric pressure and temperature (300 K) with reactant mixtures containing varying concentrations of CO 2 , N 2 , and Ar as diluents. Measured burning velocities were compared with computed results obtained from one-dimensional laminar premixed flame code PREMIX with detailed chemical kinetics and good agreement was obtained. The effectiveness of diluents in reduction of laminar burning velocity for a given diluent concentration is in the increasing order of argon, nitrogen, carbon dioxide. This may be due to increased capabilities either to quench the reaction zone by increased specific heat or due to reduced transport rates. The lean and stoichiometric H 2 /O 2 /CO 2 flames with 65% CO 2 dilution exhibited cellular flame structures. Detailed three-dimensional simulation was performed to understand lean H 2 /O 2 /CO 2 cellular flame structure and cell count from computed flame matched well with the experimental cellular flame. (author)

  14. Antiapoptotic Actions of Methyl Gallate on Neonatal Rat Cardiac Myocytes Exposed to H2O2

    Directory of Open Access Journals (Sweden)

    Sandhya Khurana

    2014-01-01

    Full Text Available Reactive oxygen species trigger cardiomyocyte cell death via increased oxidative stress and have been implicated in the pathogenesis of cardiovascular diseases. The prevention of cardiomyocyte apoptosis is a putative therapeutic target in cardioprotection. Polyphenol intake has been associated with reduced incidences of cardiovascular disease and better overall health. Polyphenols like epigallocatechin gallate (EGCG can reduce apoptosis of cardiomyocytes, resulting in better health outcomes in animal models of cardiac disorders. Here, we analyzed whether the antioxidant N-acetyl cysteine (NAC or polyphenols EGCG, gallic acid (GA or methyl gallate (MG can protect cardiomyocytes from cobalt or H2O2-induced stress. We demonstrate that MG can uphold viability of neonatal rat cardiomyocytes exposed to H2O2 by diminishing intracellular ROS, maintaining mitochondrial membrane potential, augmenting endogenous glutathione, and reducing apoptosis as evidenced by impaired Annexin V/PI staining, prevention of DNA fragmentation, and cleaved caspase-9 accumulation. These findings suggest a therapeutic value for MG in cardioprotection.

  15. Effect of residual H2O2 from advanced oxidation processes on subsequent biological water treatment: A laboratory batch study.

    Science.gov (United States)

    Wang, Feifei; van Halem, Doris; Liu, Gang; Lekkerkerker-Teunissen, Karin; van der Hoek, Jan Peter

    2017-10-01

    H 2 O 2 residuals from advanced oxidation processes (AOPs) may have critical impacts on the microbial ecology and performance of subsequent biological treatment processes, but little is known. The objective of this study was to evaluate how H 2 O 2 residuals influence sand systems with an emphasis on dissolved organic carbon (DOC) removal, microbial activity change and bacterial community evolution. The results from laboratory batch studies showed that 0.25 mg/L H 2 O 2 lowered DOC removal by 10% while higher H 2 O 2 concentrations at 3 and 5 mg/L promoted DOC removal by 8% and 28%. A H 2 O 2 dosage of 0.25 mg/L did not impact microbial activity (as measured by ATP) while high H 2 O 2 dosages, 1, 3 and 5 mg/L, resulted in reduced microbial activity of 23%, 37% and 37% respectively. Therefore, DOC removal was promoted by the increase of H 2 O 2 dosage while microbial activity was reduced. The pyrosequencing results illustrated that bacterial communities were dominated by Proteobacteria. The presence of H 2 O 2 showed clear influence on the diversity and composition of bacterial communities, which became more diverse under 0.25 mg/L H 2 O 2 but conversely less diverse when the dosage increased to 5 mg/L H 2 O 2 . Anaerobic bacteria were found to be most sensitive to H 2 O 2 as their growth in batch reactors was limited by both 0.25 and 5 mg/L H 2 O 2 (17-88% reduction). In conclusion, special attention should be given to effects of AOPs residuals on microbial ecology before introducing AOPs as a pre-treatment to biological (sand) processes. Additionally, the guideline on the maximum allowable H 2 O 2 concentration should be properly evaluated. Copyright © 2017 The Author(s). Published by Elsevier Ltd.. All rights reserved.

  16. Degradation of Sunset Yellow FCF using copper loaded bentonite and H2O2 as photo-Fenton like reagent

    Directory of Open Access Journals (Sweden)

    Kiran Chanderia

    2017-02-01

    Full Text Available In the present work, photo-Fenton degradation of Sunset Yellow FCF under visible light was carried out by using copper loaded bentonite and hydrogen peroxide. The photocatalyst was prepared by loading copper ions on bentonite by wet impregnation method. The rate of photocatalytic degradation of dye was measured spectrophotometrically by measuring absorbance of the reaction mixture at regular time intervals. The effect of various parameters such as pH, concentration of dye, amount of photocatalyst, amount of H2O2 and light intensity on the reaction rate has also been studied. Characterization of photocatalyst has been done by IR spectroscopy, scanning electron microscopy and X-ray diffraction. The Chemical Oxygen Demand (COD of the reaction mixture has been determined before and after treatment. A tentative mechanism involving ·≡OH radical as an oxidant for degradation of dye has also been proposed. Involvement of ·≡OH radicals as an active oxidizing agent has been confirmed by using isopropanol and butylated hydroxy toluene (BHT as radical scavengers. It has been observed that the rate of reaction is drastically reduced in the presence of these scavengers. The rate of reaction is much retarded by using BHT as compared with isopropanol.

  17. Real-time quantification of subcellular H2O2 and glutathione redox potential in living cardiovascular tissues.

    Science.gov (United States)

    Panieri, Emiliano; Millia, Carlo; Santoro, Massimo M

    2017-08-01

    Detecting and measuring the dynamic redox events that occur in vivo is a prerequisite for understanding the impact of oxidants and redox events in normal and pathological conditions. These aspects are particularly relevant in cardiovascular tissues wherein alterations of the redox balance are associated with stroke, aging, and pharmacological intervention. An ambiguous aspect of redox biology is how redox events occur in subcellular organelles including mitochondria, and nuclei. Genetically-encoded Rogfp2 fluorescent probes have become powerful tools for real-time detection of redox events. These probes detect hydrogen peroxide (H 2 O 2 ) levels and glutathione redox potential (E GSH ), both with high spatiotemporal resolution. By generating novel transgenic (Tg) zebrafish lines that express compartment-specific Rogfp2-Orp1 and Grx1-Rogfp2 sensors we analyzed cytosolic, mitochondrial, and the nuclear redox state of endothelial cells and cardiomyocytes of living zebrafish embryos. We provide evidence for the usefulness of these Tg lines for pharmacological compounds screening by addressing the blocking of pentose phosphate pathways (PPP) and glutathione synthesis, thus altering subcellular redox state in vivo. Rogfp2-based transgenic zebrafish lines represent valuable tools to characterize the impact of redox changes in living tissues and offer new opportunities for studying metabolic driven antioxidant response in biomedical research. Copyright © 2017 Elsevier Inc. All rights reserved.

  18. Sustained Submicromolar H2O2 Levels Induce Hepcidin via Signal Transducer and Activator of Transcription 3 (STAT3)*

    Science.gov (United States)

    Millonig, Gunda; Ganzleben, Ingo; Peccerella, Teresa; Casanovas, Guillem; Brodziak-Jarosz, Lidia; Breitkopf-Heinlein, Katja; Dick, Tobias P.; Seitz, Helmut-Karl; Muckenthaler, Martina U.; Mueller, Sebastian

    2012-01-01

    The peptide hormone hepcidin regulates mammalian iron homeostasis by blocking ferroportin-mediated iron export from macrophages and the duodenum. During inflammation, hepcidin is strongly induced by interleukin 6, eventually leading to the anemia of chronic disease. Here we show that hepatoma cells and primary hepatocytes strongly up-regulate hepcidin when exposed to low concentrations of H2O2 (0.3–6 μm), concentrations that are comparable with levels of H2O2 released by inflammatory cells. In contrast, bolus treatment of H2O2 has no effect at low concentrations and even suppresses hepcidin at concentrations of >50 μm. H2O2 treatment synergistically stimulates hepcidin promoter activity in combination with recombinant interleukin-6 or bone morphogenetic protein-6 and in a manner that requires a functional STAT3-responsive element. The H2O2-mediated hepcidin induction requires STAT3 phosphorylation and is effectively blocked by siRNA-mediated STAT3 silencing, overexpression of SOCS3 (suppressor of cytokine signaling 3), and antioxidants such as N-acetylcysteine. Glycoprotein 130 (gp130) is required for H2O2 responsiveness, and Janus kinase 1 (JAK1) is required for adequate basal signaling, whereas Janus kinase 2 (JAK2) is dispensable upstream of STAT3. Importantly, hepcidin levels are also increased by intracellular H2O2 released from the respiratory chain in the presence of rotenone or antimycin A. Our results suggest a novel mechanism of hepcidin regulation by nanomolar levels of sustained H2O2. Thus, similar to cytokines, H2O2 provides an important regulatory link between inflammation and iron metabolism. PMID:22932892

  19. HF/H2O2 treated graphite felt as the positive electrode for vanadium redox flow battery

    Science.gov (United States)

    He, Zhangxing; Jiang, Yingqiao; Meng, Wei; Jiang, Fengyun; Zhou, Huizhu; Li, Yuehua; Zhu, Jing; Wang, Ling; Dai, Lei

    2017-11-01

    In order to improve the electrochemical performance of the positive graphite felt electrode in vanadium flow redox battery, a novel method is developed to effectively modify the graphite felt by combination of etching of HF and oxidation of H2O2. After the etching of HF for the graphite felt at ambient temperature, abundant oxygen-containing functional groups were further introduced on the surface of graphite felt by hydrothermal treatment using H2O2 as oxidant. Benefiting from the surface etching and introduction of functional groups, mass transfer and electrode process can be improved significantly on the surface of graphite felt. VO2+/VO2+ redox reaction on the graphite felt modified by HF and H2O2 jointly (denote: GF-HF/H2O2) exhibits superior electrochemical kinetics in comparison with the graphite felt modified by single HF or H2O2 treatment. The cell using GF-HF/H2O2 as the positive electrode was assembled and its electrochemical properties were evaluated. The increase of energy efficiency of 4.1% for GF-HF/H2O2 at a current density of 50 mA cm-2 was obtained compared with the pristine graphite felt. The cell using GF-HF/H2O2 also demonstrated higher discharge capacity. Our study revealed that HF/H2O2 treatment is an efficient method to enhance the electrochemical performance of graphite felt, further improving the comprehensive energy storage performance of the vanadium flow redox battery.

  20. H2O2 can Increase Lignin Disintegration and Decrease Cellulose Decomposition in the Process of Solid-State Fermentation (SSF) by Aspergillus oryzae Using Corn Stalk as Raw Materials

    OpenAIRE

    Zhicai Zhang; Jun Jia; Ming Li; Qiaoxia Pang

    2014-01-01

    H2O2 is both bactericidal and the main oxidant responsible for lignin degradation reaction catalyzed by manganese peroxidase (MnP) and lignin peroxidase (LiP). Thus, H2O2 treatment of corn stalk and the implementation of solid-substrate fermentation (SSF) is possible to increase the removal rate of lignin from stalk in the process of SSF and after SSF, while avoiding the need to sterilize the raw materials. To demonstrate this approach, SSF was initially carried out using corn stalk pretreate...

  1. H2O2 homeostasis in wild-type and ethylene-insensitive Never ripe tomato in response to salicylic acid treatment in normal photoperiod and in prolonged darkness.

    Science.gov (United States)

    Takács, Zoltán; Poór, Péter; Borbély, Péter; Czékus, Zalán; Szalai, Gabriella; Tari, Irma

    2018-05-01

    Ethylene proved to be an important modulator of salicylic acid (SA) signalling pathway. Since SA may regulate both the production and scavenging of hydrogen peroxide (H 2 O 2 ), which show light-dependency, the aim of this study was to compare H 2 O 2 metabolism in the leaves of SA-treated wild-type (WT) tomato (Solanum lycopersicum L. cv. Ailsa Craig) and in ethylene receptor Never-ripe (Nr) mutants grown in normal photoperiod or in prolonged darkness. H 2 O 2 accumulation was higher in the WT than in the mutants in normal photoperiod after 1 mM SA treatment, while Nr leaves contained more H 2 O 2 after light deprivation. The expression of certain superoxide dismutase (SOD) genes and activity of the enzyme followed the same tendency as H 2 O 2 , which was scavenged by different enzymes in the two genotypes. Catalase (CAT, EC 1.11.1.6) activity was inhibited by SA in WT, while the mutants maintained enhanced enzyme activity in the dark. Thus, in WT, CAT inhibition was the major component of the H 2 O 2 accumulation elicited by 1 mM SA in a normal photoperiod, since the expression and/or activity of ascorbate (APX, EC 1.11.1.11) and guaiacol peroxidases (POD, EC 1.11.1.7) were induced in the leaves. The absence of APX and POD activation in mutant plants suggests that the regulation of these enzymes by SA needs functional ethylene signalling. While the block of ethylene perception in Nr mutants was overwritten in the transcription and activity of certain SOD and CAT isoenzymes during prolonged darkness, the low APX and POD activities led to H 2 O 2 accumulation in these tissues. Copyright © 2018 Elsevier Masson SAS. All rights reserved.

  2. Oxidation of Alkenes with H2O2 by an in-Situ Prepared Mn(II)/Pyridine-2-carboxylic Acid Catalyst and the Role of Ketones in Activating H2O2

    NARCIS (Netherlands)

    Dong, Jia Jia; Saisaha, Pattama; Meinds, Tim G.; Alsters, Paul L.; Ijpeij, Edwin G.; van Summeren, Ruben P.; Mao, Bin; Fananas-Mastral, Martin; de Boer, Johannes W.; Hage, Ronald; Feringa, Ben L.; Browne, Wesley R.

    A simple, high yielding catalytic method for the multigram scale selective epoxidation of electron-rich alkenes using near-stoichiometric H2O2 under ambient conditions is reported. The system consists of a Mn(II) salt (

  3. Clofibric acid degradation in UV254/H2O2 process: effect of temperature.

    Science.gov (United States)

    Li, Wenzhen; Lu, Shuguang; Qiu, Zhaofu; Lin, Kuangfei

    2010-04-15

    The degradation of clofibric acid (CA) in UV(254)/H(2)O(2) process under three temperature ranges, i.e. T1 (9.0-11.5 degrees C), T2 (19.0-21.0 degrees C) and T3 (29.0-30.0 degrees C) was investigated. The effects of solution constituents including NO(3)(-) and HCO(3)(-) anions, and humic acid (HA) on CA degradation were evaluated in Milli-Q waters. CA degradation behaviors were simulated with the pseudo-first-order kinetic model and the apparent rate constant (k(ap)) and half-life time (t(1/2)) were calculated. The results showed that higher temperature would favor CA degradation, and CA degradation was taken place mostly by indirect oxidation through the formation of OH radicals in UV(254)/H(2)O(2) process. In addition, the effects of both NO(3)(-) and HCO(3)(-) anions at two selected concentrations (1.0x10(-3) and 0.1 mol L(-1)) and HA (20 mg L(-1)) on CA degradation were investigated. The results showed that HA had negative effect on CA degradation, and this effect was much more apparent under low temperature condition. On the other hand, the inhibitive effect on CA degradation at both lower and higher concentrations of bicarbonate was observed, and this inhibitive effect was much more apparent at higher bicarbonate concentration and lower temperature condition. While, at higher nitrate concentration the inhibitive effect on CA degradation under three temperature ranges was observed, and with the temperature increase this negative effect was apparently weakened. However, at lower nitrate concentration a slightly positive effect on CA degradation was found under T2 and T3 conditions. Moreover, when using a real wastewater treatment plant (WWTP) effluent spiked with CA over 99% of CA removal could be achieved under 30 degrees C within only 15 min compared with 40 and 80 min under 20 and 10 degrees C respectively, suggesting a significant promotion in CA degradation under higher temperature condition. Therefore, it can be concluded that temperature plays an

  4. Neuroprotective and antioxidant activities of bamboo salt soy sauce against H2O2-induced oxidative stress in rat cortical neurons.

    Science.gov (United States)

    Jeong, Jong Hee; Noh, Min-Young; Choi, Jae-Hyeok; Lee, Haiwon; Kim, Seung Hyun

    2016-04-01

    Bamboo salt (BS) and soy sauce (SS) are traditional foods in Asia, which contain antioxidants that have cytoprotective effects on the body. The majority of SS products contain high levels of common salt, consumption of which has been associated with numerous detrimental effects on the body. However, BS may be considered a healthier substitute to common salt. The present study hypothesized that SS made from BS, known as bamboo salt soy sauce (BSSS), may possess enhanced cytoprotective properties; this was evaluated using a hydrogen peroxide (H 2 O 2 )-induced neuronal cell death rat model. Rat neuronal cells were pretreated with various concentrations (0.001, 0.01, 0.1, 1 and 10%) of BSSS, traditional soy sauce (TRSS) and brewed soy sauce (BRSS), and were subsequently exposed to H 2 O 2 (100 µM). The viability of neuronal cells, and the occurrence of DNA fragmentation, was subsequently examined. Pretreatment of neuronal cells with TRSS and BRSS reduced cell viability in a concentration-dependent manner, whereas neuronal cells pretreated with BSSS exhibited increased cell viability, as compared with non-treated neuronal cells. Furthermore, neuronal cells pretreated with 0.01% BSSS exhibited the greatest increase in viability. Exposure of neuronal cells to H 2 O 2 significantly increased the levels of reactive oxygen species (ROS), B-cell lymphoma 2-associated X protein, poly (ADP-ribose), cleaved poly (ADP-ribose) polymerase, cytochrome c , apoptosis-inducing factor, cleaved caspase-9 and cleaved caspase-3, in all cases. Pretreatment of neuronal cells with BSSS significantly reduced the levels of ROS generated by H 2 O 2 , and increased the levels of phosphorylated AKT and phosphorylated glycogen synthase kinase-3β. Furthermore, the observed effects of BSSS could be blocked by administration of 10 µM LY294002, a phosphatidylinositol 3-kinase inhibitor. The results of the present study suggested that BSSS may exert positive neuroprotective effects against H 2 O 2

  5. The Sabatier Principle Illustrated by Catalytic H2O2 Decomposition on Metal Surfaces

    DEFF Research Database (Denmark)

    Laursen, Anders Bo; Man, Isabela Costinela; Trinhammer, Ole

    2011-01-01

    Heterogeneous catalysis is important in today’s industry. Hence, it is imperative to introduce students to this field and its tools. A new way of introducing one of these tools, the Sabatier principle, via a laboratory exercise is presented. A volcano plot is constructed for the well-known hetero......Heterogeneous catalysis is important in today’s industry. Hence, it is imperative to introduce students to this field and its tools. A new way of introducing one of these tools, the Sabatier principle, via a laboratory exercise is presented. A volcano plot is constructed for the well......-known heterogeneous H2O2 catalytic decomposition reaction on various metal foils. The activity per catalyst surface area versus the computationally calculated binding energy of OH groups on the catalysts is plotted. The OH group is identified as the only surface intermediate in an intuitive reaction mechanism...

  6. Cell death in the unicellular green alga Micrasterias upon H2O2 induction

    Science.gov (United States)

    Darehshouri, Anza; Affenzeller, Matthias; Lütz-Meindl, Ursula

    2010-01-01

    In the present study we investigate whether the unicellular green alga Micrasterias denticulata is capable of executing programmed cell death (PCD) upon experimental induction and by which morphological, molecular and physiological hallmarks it is characterized. This is particularly interesting as unicellular fresh water green algae growing in shallow bog ponds are exposed to extreme environmental conditions and the capability to perform PCD may provide an important strategy to guarantee survival of the population. The theoretically “immortal” alga Micrasterias is an ideal object for such investigations as it has served as a cell biological model system since many years and details on its growth properties, physiology and ultrastructure throughout the cell cycle are well known. Treatment with low concentrations of H2O2 known to induce PCD in other organisms resulted in severe ultrastructural changes of organelles as observed in TEM. These include deformation and partly disintegration of mitochondria, abnormal dilatation of cisternal rims of dictyosomes, the occurrence of multivesicular bodies, an increase in the number of ER compartments and slight condensation of chromatin. Additionally, a statistically significant increase in caspase-3-like activity could be detected which was abrogated by a caspase-3 inhibitor. Photosynthetic activity measured by fast chlorophyll fluorescence decreased as a consequence of H2O2 exposure whereas pigment composition, except of a reduction in carotenoids, was the same as in untreated controls. TUNEL positive staining and ladder-like degradation of DNA, both frequently regarded as PCD hallmark in higher plants could only be detected in dead Micrasterias cells. PMID:18950431

  7. Measurements and Modeling of SiCl(4) Combustion in a Low-Pressure H2/O2 Flame

    National Research Council Canada - National Science Library

    Moore, T; Brady, B; Martin, L. R

    2006-01-01

    .... A gas-phase chemical kinetics mechanism for the combustion of SiCl in an H2/O2/Ar flame was proposed, and experimental results were compared with predictions for a premixed, one-dimensional laminar...

  8. The Effects of Nitroxyl (HNO) on H2O2 Metabolism and Possible Mechanisms of HNO Signaling

    OpenAIRE

    Jackson, Matthew I.; Fields, Hannah F.; Lujan, Timothy S.; Cantrell, Megan M.; Lin, Joseph; Fukuto, Jon M.

    2013-01-01

    Nitroxyl (HNO) possesses unique and potentially important biological/physiological activity that is currently mechanistically ill-defined. Previous work has shown that the likely biological targets for HNO are thiol proteins, oxidized metalloproteins (i.e. ferric heme proteins) and, most likely, selenoproteins. Interestingly, these are the same classes of proteins that interact with H2O2. In fact, these classes of proteins not only react with H2O2, and thus potentially responsible for the sig...

  9. Using H2O2 treatments for the degradation of cyanobacteria and microcystins in a shallow hypertrophic reservoir.

    Science.gov (United States)

    Papadimitriou, Theodoti; Kormas, Konstantinos; Dionysiou, Dionysios D; Laspidou, Chrysi

    2016-11-01

    Toxins produced by cyanobacteria in freshwater ecosystems constitute a serious health risk worldwide for humans that may use the affected water bodies for recreation, drinking water, and/or irrigation. Cyanotoxins have also been deemed responsible for loss of animal life in many places around the world. This paper explores the effect of H 2 O 2 treatments on cyanobacteria and microcystins in natural samples from a hypertrophic reservoir in microcosm experiments. According to the results, cyanobacteria were more easily affected by H 2 O 2 than by other phytoplanktonic groups. This was shown by the increase in the fractions of chlorophyll-a (a proxy for phytoplankton) and chlorophyll-b (a proxy for green algae) over total phytoplankton pigments and the decrease in the fraction of phycocyanin (a proxy for cyanobacteria) over total phytoplankton pigments. Thus, while an overall increase in phytoplankton occurred, a preferential decrease in cyanobacteria was observed with H 2 O 2 treatments over a few hours. Moreover, significant degradation of total microcystins was observed under H 2 O 2 treatments, while more microcystins were degraded when UV radiation was used in combination with H 2 O 2 . The combination of H 2 O 2 and ultraviolet (UV) treatment in natural samples resulted in total microcystin concentrations that were below the World Health Organization limit for safe consumption of drinking water of 1 μg/L. Although further investigation into the effects of H 2 O 2 addition on ecosystem function must be performed, our results show that the application of H 2 O 2 could be a promising method for the degradation of microcystins in reservoirs and the reduction of public health risks related to the occurrence of harmful algal blooms.

  10. Tyrphostin AG-related compounds attenuate H2O2-induced TRPM2-dependent and -independent cellular responses.

    Science.gov (United States)

    Yamamoto, Shinichiro; Toda, Takahiro; Yonezawa, Ryo; Negoro, Takaharu; Shimizu, Shunichi

    2017-05-01

    TRPM2 is a Ca 2+ -permeable channel that is activated by H 2 O 2 . TRPM2-mediated Ca 2+ signaling has been implicated in the aggravation of inflammatory diseases. Therefore, the development of TRPM2 inhibitors to prevent the aggravation of these diseases is expected. We recently reported that some Tyrphostin AG-related compounds inhibited the H 2 O 2 -induced activation of TRPM2 by scavenging the intracellular hydroxyl radical. In the present study, we examined the effects of AG-related compounds on H 2 O 2 -induced cellular responses in human monocytic U937 cells, which functionally express TRPM2. The effects of AG-related compounds on H 2 O 2 -induced changes in intracellular Ca 2+ concentrations, extracellular signal-regulated kinase (ERK) activation, and CXCL8 secretion were assessed using U937 cells. Ca 2+ influxes via TRPM2 in response to H 2 O 2 were blocked by AG-related compounds. AG-related compounds also inhibited the H 2 O 2 -induced activation of ERK, and subsequent secretion of CXCL8 mediated by TRPM2-dependent and -independent mechanisms. Our results show that AG-related compounds inhibit H 2 O 2 -induced CXCL8 secretion following ERK activation, which is mediated by TRPM2-dependent and -independent mechanisms in U937 cells. We previously reported that AG-related compounds blocked H 2 O 2 -induced TRPM2 activation by scavenging the hydroxyl radical. The inhibitory effects of AG-related compounds on TRPM2-independent responses may be due to scavenging of the hydroxyl radical. Copyright © 2017 The Authors. Production and hosting by Elsevier B.V. All rights reserved.

  11. Decolorizing of azo dye Reactive red 24 aqueous solution using exfoliated graphite and H2O2 under ultrasound irradiation.

    Science.gov (United States)

    Li, Mei; Li, Ji-Tai; Sun, Han-Wen

    2008-07-01

    At its natural pH (6.95), the decolorization of Reactive red 24 in ultrasound, ultrasound/H2O2, exfoliated graphite, ultrasound/exfoliated graphite, exfoliated graphite/H2O2 and ultrasound/exfoliated graphite/H2O2 systems were compared. An enhancement was observed for the decolorization in ultrasound/exfoliated graphite/H2O2 system. The effect of solution pH, H2O2 and exfoliated graphite dosages, and temperature on the decolorization of Reactive red 24 was investigated. The sonochemical treatment in combination with exfoliated graphite/H2O2 showed a synergistic effect for the decolorization of Reactive red 24. The results indicated that under proper conditions, there was a possibility to remove Reactive red 24 very efficient from aqueous solution. The decolorization of other azo dyes (Reactive red 2, Methyl orange, Acid red 1, Acid red 73, Acid red 249, Acid orange 7, Acid blue 113, Acid brown 75, Acid green 20, Acid yellow 42, Acid mordant brown 33, Acid mordant yellow 10 and Direct green 1) was also investigated, at their natural pH.

  12. Combinative dyebath treatment with activated carbon and UV/H2O2: a case study on Everzol Black-GSP.

    Science.gov (United States)

    Ince, N H; Hasan, D A; Ustün, B; Tezcanli, G

    2002-01-01

    Treatability of textile dyebath effluents by two simultaneously operated processes comprising adsorption and advanced oxidation was investigated using a reactive dyestuff, Everzol Black-GSP (EBG). The method was comprised of contacting aqueous solutions of the dye with hydrogen peroxide and granules of activated carbon (GAC) during irradiation of the reactor with ultraviolet light (UV). Control experiments were run separately with each individual process (advanced oxidation with UV/H2O2 and adsorption on GAC) to select the operating parameters on the basis of maximum color removal. The effectiveness of the combined scheme was tested by monitoring the rate of decolorization and the degree of carbon mineralization in effluent samples. It was found that in a combined medium of advanced oxidation and adsorption, color was principally removed by oxidative degradation, while adsorption contributed to the longer process of dye mineralization. Economic evaluation of the system based on total color removal and 50% mineralization showed that in the case of Everzol Black-GSP, which adsorbs relatively poorly on GAC, the proposed combination provides 25% and 35% reduction in hydrogen peroxide and energy consumption relative to the UV/H2O2 system. Higher cost reductions are expected in cases with well adsorbing dyes and/or with less costly adsorbents.

  13. Chlorogenic acid analogues from Gynura nepalensis protect H9c2 cardiomyoblasts against H2O2-induced apoptosis.

    Science.gov (United States)

    Yu, Bang-Wei; Li, Jin-Long; Guo, Bin-Bin; Fan, Hui-Min; Zhao, Wei-Min; Wang, He-Yao

    2016-11-01

    Chlorogenic acid has shown protective effect on cardiomyocytes against oxidative stress-induced damage. Herein, we evaluated nine caffeoylquinic acid analogues (1-9) isolated from the leaves of Gynura nepalensis for their protective effect against H 2 O 2 -induced H9c2 cardiomyoblast damage and explored the underlying mechanisms. H9c2 cardiomyoblasts were exposed to H 2 O 2 (0.3 mmol/L) for 3 h, and cell viability was detected with MTT assay. Hoechst 33342 staining was performed to evaluate cell apoptosis. MMPs (mitochondrial membrane potentials) were measured using a JC-1 assay kit, and ROS (reactive oxygen species) generation was measured using CM-H 2 DCFDA. The expression levels of relevant proteins were detected using Western blot analysis. Exposure to H 2 O 2 markedly decreased the viability of H9c2 cells and catalase activity, and increased LDH release and intracellular ROS production; accompanied by a loss of MMP and increased apoptotic rate. Among the 9 chlorogenic acid analogues as well as the positive control drug epigallocatechin gallate (EGCG) tested, compound 6 (3,5-dicaffeoylquinic acid ethyl ester) was the most effective in protecting H9c2 cells from H 2 O 2 -induced cell death. Pretreatment with compound 6 (1.56-100 μmol/L) dose-dependently alleviated all the H 2 O 2 -induced detrimental effects. Moreover, exposure to H 2 O 2 significantly increased the levels of Bax, p53, cleaved caspase-8, and cleaved caspase-9, and decreased the level of Bcl-2, resulting in cell apoptosis. Exposure to H 2 O 2 also significantly increased the phosphorylation of p38, JNK and ERK in the H9c2 cells. Pretreatment with compound 6 (12.5 and 25 μmol/L) dose-dependently inhibited the H 2 O 2 -induced increase in the level of cleaved caspase-9 but not of cleaved caspase-8. It also dose-dependently suppressed the H 2 O 2 -induced phosphorylation of JNK and ERK but not that of p38. Compound 6 isolated from the leaves of Gynura nepalensis potently protects H9c2

  14. Study on gamma-irradiation degradation of chitosan swollen in H2O2 solution and its antimicrobial activity for E. coli

    International Nuclear Information System (INIS)

    Dang Xuan Du; Bui Phuoc Phuc; Tran Thi Thuy; Le Anh Quoc; Dang Van Phu; Nguyen Quoc Hien

    2014-01-01

    Degradation of chitosan in swollen state with hydrogen peroxide solution (5% w/v) by γ-irradiation was investigated. Molecular weight (M w ) of irradiated chitosan was determined by gel permeation chromatography (GPC). Fourier transform infrared (FT-IR) and ultraviolet-visible (UV-vis) spectra were analyzed to study the structure changes of degraded chitosan. The results showed that the chitosan of low M w (30-45 kDa) was efficiently prepared by γ-irradiation of chitosan swollen in hydrogen peroxide solution at low dose less than 20 kGy. The main structure as well as the degree of deacetylation of the degraded chitosan was almost no significant change. Furthermore, the radiation degradation yield (G s ) was remarkably enhanced by the presence of H 2 O 2 . The obtained low M w chitosan revealed high antimicrobial activity for E. coli that can be used for food preservation and other purposes as well. (author)

  15. A novel and quick method to avoid H2O2 interference on COD measurement in Fenton system by Na2SO3 reduction and O2 oxidation

    DEFF Research Database (Denmark)

    Wang, Yong; Li, Weiguang; Angelidaki, Irini

    2013-01-01

    Hydrogen peroxide interference on chemical oxygen demand (COD) measurement has been a big problem in the application of the Fenton process. However, there is no simple and effective method available to address this problem, although several methods have been reported in the literature. In this st......Hydrogen peroxide interference on chemical oxygen demand (COD) measurement has been a big problem in the application of the Fenton process. However, there is no simple and effective method available to address this problem, although several methods have been reported in the literature...... to be effective in the matrix of Fenton treating real landfill leachate. Meanwhile, the procedure for this method in other applications was proposed in detail. To the best of our knowledge, this newly developed method is the most simple and effective way to avoid H2O2 interference on COD analysis....

  16. Increase vs. decrease of calcium uptake by isolated heart cells induced by H2O2 vs. HOCl

    International Nuclear Information System (INIS)

    Kaminishi, T.; Matsuoka, T.; Yanagishita, T.; Kako, K.J.

    1989-01-01

    Adult rat heart myocytes were labeled rapidly with exogenous [45Ca2+]. Addition of 2.5 mM H2O2 to the heart cell suspension raised the content of rapidly exchangeable intracellular Ca2+ twofold, whereas addition of 1-30 mM HOCl decreased the Ca2+ content. The H2O2-induced increase in Ca2+ content was dependent on the medium Na+, pH, and temperature but was not significantly affected by addition of verapamil, diltiazem, amiloride, or 3-aminobenzamide. The [3H]ouabain binding to myocytes was suppressed by H2O2, whereas the Ca2+ efflux from myocytes was not influenced. An uncoupler, carbonyl cyanide m-chlorophenylhydrazone, reduced Ca2+ content, implying that the H2O2-induced change in Ca2+ content was not directly related to ATP depletion. On the other hand, the H2O2-induced Ca2+ accumulation in myocytes was prevented by deferoxamine or o-phenanthroline. These results suggest that H2O2 inhibited Na+-K+-ATPase, resulting in an increase in intracellular Na+ concentration and stimulation of sarcolemmal Na+-Ca2+ exchange activity, which caused a transient net Ca2+ influx into myocytes. By contrast, HOCl decreased the Ca2+ content of the rapidly exchangeable pool below control levels and this action of HOCl was antagonized by 1,4-dithiothreitol. HOCl accelerated Ca2+ efflux from myocytes. Ca2+ uptake and Ca2+-ATPase of the isolated sarcoplasmic reticular (SR) fraction were highly sensitive to the action of HOCl. Ca2+ uptake by intracellular sites, studied with myocytes permeabilized with digitonin, was inhibited by both H2O2 and HOCl. Thus these results suggest that HOCl inhibits the SR Ca2+ pump, resulting in the observed acceleration of Ca2+ efflux from and decline in Ca2+ content of myocytes

  17. Allicin protects against H2O2-induced apoptosis of PC12 cells via the mitochondrial pathway.

    Science.gov (United States)

    Lv, Runxiao; Du, Lili; Lu, Chunwen; Wu, Jinhui; Ding, Muchen; Wang, Chao; Mao, Ningfang; Shi, Zhicai

    2017-09-01

    Allicin is a major bioactive ingredient of garlic and has a broad range of biological activities. Allicin has been reported to protect against cell apoptosis induced by H 2 O 2 in human umbilical vein endothelial cells. The present study evaluated the neuroprotective effect of allicin on the H 2 O 2 -induced apoptosis of rat pheochromocytoma PC12 cells in vitro and explored the underlying mechanism involved. PC12 cells were incubated with increasing concentrations of allicin and the toxic effect of allicin was measured by MTT assay. The cells were pretreated for 24 h with low dose (L-), medium dose (M-) and high dose (H-) of allicin, followed by exposure to 200 µM H 2 O 2 for 2 h, and the cell viability was examined by MTT assay. In addition, cell apoptosis rate was analyzed by Annexin V-FITC/PI assay, while intracellular reactive oxygen species (ROS) and mitochondrial transmembrane potential (∆ψm) were measured by flow cytometry. Bcl-2, Bax, cleaved-caspase-3 and cytochrome c (Cyt C) in the mitochondria were also examined by western blotting. The results demonstrated that 0.01 µg/ml (L-allicin), 0.1 µg/ml (M-allicin) and 1 µg/ml (H-allicin) were non-toxic doses of allicin. Furthermore, H 2 O 2 reduced cell viability, promoted cell apoptosis, induced ROS production and decreased ∆ψm. However, allicin treatment reversed the effect of H 2 O 2 in a dose-dependent manner. It was also observed that H 2 O 2 exposure significantly decreased Bcl-2 and mitochondrial Cyt C, while it increased Bax and cleaved-caspase-3, which were attenuated by allicin pretreatment. The results revealed that allicin protected PC12 cells from H 2 O 2 -induced cell apoptosis via the mitochondrial pathway, suggesting the potential neuroprotective effect of allicin against neurological diseases.

  18. NO and H2O2 contribute to SO2 toxicity via Ca2+ signaling in Vicia faba guard cells.

    Science.gov (United States)

    Yi, Min; Bai, Heli; Xue, Meizhao; Yi, Huilan

    2017-04-01

    NO and H 2 O 2 have been implicated as important signals in biotic and abiotic stress responses of plants to the environment. Previously, we have shown that SO 2 exposure increased the levels of NO and H 2 O 2 in plant cells. We hypothesize that, as signaling molecules, NO and H 2 O 2 mediate SO 2 -caused toxicity. In this paper, we show that SO 2 hydrates caused guard cell death in a concentration-dependent manner in the concentration range of 0.25 to 6 mmol L -1 , which was associated with elevation of intracellular NO, H 2 O 2 , and Ca 2+ levels in Vicia faba guard cells. NO donor SNP enhanced SO 2 toxicity, while NO scavenger c-PTIO and NO synthesis inhibitors L-NAME and tungstate significantly prevented SO 2 toxicity. ROS scavenger ascorbic acid (AsA) and catalase (CAT), Ca 2+ chelating agent EGTA, and Ca 2+ channel inhibitor LaCl 3 also markedly blocked SO 2 toxicity. In addition, both c-PTIO and AsA could completely block SO 2 -induced elevation of intracellular Ca 2+ level. Moreover, c-PTIO efficiently blocked SO 2 -induced H 2 O 2 elevation, and AsA significantly blocked SO 2 -induced NO elevation. These results indicate that extra NO and H 2 O 2 are produced and accumulated in SO 2 -treated guard cells, which further activate Ca 2+ signaling to mediate SO 2 toxicity. Our findings suggest that both NO and H 2 O 2 contribute to SO 2 toxicity via Ca 2+ signaling.

  19. Trace Element Removal in Distributed Drinking Water Treatment Systems by Cathodic H2O2 Production and UV Photolysis.

    Science.gov (United States)

    Barazesh, James M; Prasse, Carsten; Wenk, Jannis; Berg, Stephanie; Remucal, Christina K; Sedlak, David L

    2018-01-02

    As water scarcity intensifies, point-of-use and point-of-entry treatment may provide a means of exploiting locally available water resources that are currently considered to be unsafe for human consumption. Among the different classes of drinking water contaminants, toxic trace elements (e.g., arsenic and lead) pose substantial operational challenges for distributed drinking water treatment systems. Removal of toxic trace elements via adsorption onto iron oxides is an inexpensive and robust treatment method; however, the presence of metal-complexing ligands associated with natural organic matter (NOM) often prevents the formation of iron precipitates at the relatively low concentrations of dissolved iron typically present in natural water sources, thereby requiring the addition of iron which complicates the treatment process and results in a need to dispose of relatively large amounts of accumulated solids. A point-of-use treatment device consisting of a cathodic cell that produced hydrogen peroxide (H 2 O 2 ) followed by an ultraviolet (UV) irradiation chamber was used to decrease colloid stabilization and metal-complexing capacity of NOM present in groundwater. Exposure to UV light altered NOM, converting ∼6 μM of iron oxides into settable forms that removed between 0.5 and 1 μM of arsenic (As), lead (Pb), and copper (Cu) from solution via adsorption. After treatment, changes in NOM consistent with the loss of iron-complexing carboxylate ligands were observed, including decreases in UV absorbance and shifts in the molecular composition of NOM to higher H/C and lower O/C ratios. Chronoamperometric experiments conducted in synthetic groundwater revealed that the presence of Ca 2+ and Mg 2+ inhibited intramolecular charge-transfer within photoexcited NOM, leading to substantially increased removal of iron and trace elements.

  20. Degradation of Acid Blue 25 in aqueous media using 1700kHz ultrasonic irradiation: ultrasound/Fe(II) and ultrasound/H(2)O(2) combinations.

    Science.gov (United States)

    Ghodbane, Houria; Hamdaoui, Oualid

    2009-06-01

    In this work, the sonolytic degradation of an anthraquinonic dye, C.I. Acid Blue 25 (AB25), in aqueous phase using high frequency ultrasound waves (1700kHz) for an acoustic power of 14W was investigated. The sonochemical efficiency of the reactor was evaluated by potassium iodide dosimeter, Fricke reaction and hydrogen peroxide production yield. The three investigated methods clearly show the production of oxidizing species during sonication and well reflect the sonochemical effects of high frequency ultrasonic irradiation. The effect of operational conditions such as the initial AB25 concentration, solution temperature and pH on the degradation of AB25 was studied. Additionally, the influence of addition of salts on the degradation of dye was examined. The rate of AB25 degradation was dependent on initial dye concentration, pH and temperature. Addition of salts increased the degradation of dye. Experiments conducted using distilled and natural waters demonstrated that the degradation was more efficient in the natural water compared to distilled water. To increase the efficiency of AB25 degradation, experiments combining ultrasound with Fe(II) or H(2)O(2) were conducted. Fe(II) induced the dissociation of ultrasonically produced hydrogen peroxide, leading to additional OH radicals which enhance the degradation of dye. The combination of ultrasound with hydrogen peroxide looks to be a promising option to increase the generation of free radicals. The concentration of hydrogen peroxide plays a crucial role in deciding the extent of enhancement obtained for the combined process. The results of the present work indicate that ultrasound/H(2)O(2) and ultrasound/Fe(II) processes are efficient for the degradation of AB25 in aqueous solutions by high frequency ultrasonic irradiation.

  1. Fate Of Fissile Material Bound To Monosodium Titanate During Cooper Catalyzed Peroxide Oxidation Of Tank 48H Waste

    International Nuclear Information System (INIS)

    Taylor-Pashow, K.

    2012-01-01

    At the Savannah River Site (SRS), Tank 48H currently holds approximately 240,000 gallons of slurry which contains potassium and cesium tetraphenylborate (TPB). A copper catalyzed peroxide oxidation (CCPO) reaction is currently being examined as a method for destroying the TPB present in Tank 48H. Part of the development of that process includes an examination of the fate of the Tank 48H fissile material which is adsorbed onto monosodium titanate (MST) particles. This report details results from experiments designed to examine the potential degradation of MST during CCPO processing and the subsequent fate of the adsorbed fissile material. Experiments were conducted to simulate the CCPO process on MST solids loaded with sorbates in a simplified Tank 48H simulant. Loaded MST solids were placed into the Tank 48H simplified simulant without TPB, and the experiments were then carried through acid addition (pH adjustment to 11), peroxide addition, holding at temperature (50 C) for one week, and finally NaOH addition to bring the free hydroxide concentration to a target concentration of 1 M. Testing was conducted without TPB to show the maximum possible impact on MST since the competing oxidation of TPB with peroxide was absent. In addition, the Cu catalyst was also omitted, which will maximize the interaction of H 2 O 2 with the MST; however, the results may be non-conservative assuming the Cu-peroxide active intermediate is more reactive than the peroxide radical itself. The study found that both U and Pu desorb from the MST when the peroxide addition begins, although to different extents. Virtually all of the U goes into solution at the beginning of the peroxide addition, whereas Pu reaches a maximum of ∼34% leached during the peroxide addition. Ti from the MST was also found to come into solution during the peroxide addition. Therefore, Ti is present with the fissile in solution. After the peroxide addition is complete, the Pu and Ti are found to precipitate from

  2. Extensin network formation in Vitis vinifera callus cells is an essential and causal event in rapid and H2O2-induced reduction in primary cell wall hydration

    Science.gov (United States)

    2011-01-01

    Background Extensin deposition is considered important for the correct assembly and biophysical properties of primary cell walls, with consequences to plant resistance to pathogens, tissue morphology, cell adhesion and extension growth. However, evidence for a direct and causal role for the extensin network formation in changes to cell wall properties has been lacking. Results Hydrogen peroxide treatment of grapevine (Vitis vinifera cv. Touriga) callus cell walls was seen to induce a marked reduction in their hydration and thickness. An analysis of matrix proteins demonstrated this occurs with the insolubilisation of an abundant protein, GvP1, which displays a primary structure and post-translational modifications typical of dicotyledon extensins. The hydration of callus cell walls free from saline-soluble proteins did not change in response to H2O2, but fully regained this capacity after addition of extensin-rich saline extracts. To assay the specific contribution of GvP1 cross-linking and other wall matrix proteins to the reduction in hydration, GvP1 levels in cell walls were manipulated in vitro by binding selected fractions of extracellular proteins and their effect on wall hydration during H2O2 incubation assayed. Conclusions This approach allowed us to conclude that a peroxidase-mediated formation of a covalently linked network of GvP1 is essential and causal in the reduction of grapevine callus wall hydration in response to H2O2. Importantly, this approach also indicated that extensin network effects on hydration was only partially irreversible and remained sensitive to changes in matrix charge. We discuss this mechanism and the importance of these changes to primary wall properties in the light of extensin distribution in dicotyledons. PMID:21672244

  3. A unique polysaccharide purified from Hericium erinaceus mycelium prevents oxidative stress induced by H2O2 in human gastric mucosa epithelium cell.

    Directory of Open Access Journals (Sweden)

    Mingxing Wang

    Full Text Available Hericium erinaceus (HE has been used both as a traditional Chinese medicine and home remedy for treatment of gastric and duodenal ulcers and gastritis. EP-1, a purified polysaccharide isolated from HE mycelium, has recently been identified as the active component responsible for HE anti-gastritis activity. Because oxidative stress has been implicated as a pathogenic cause of gastritis and gastric ulcers, EP-1 antioxidant properties were systematically examined in vitro using the human gastric mucosal epithelial cell line, GES-1. Results showed that EP-1 possessed higher oxygen radical absorbance capacity (ORAC and 2-3 times higher ability to scavenge 2,2-diphenyl-1-picrylhydrazyl (DPPH, superoxide and hydroxyl radicals than a hot water extract of commercially available HE fruiting body. A crude mycelial polysaccharide (CMPS extract of HE, from which EP-1 was purified, showed slightly stronger radical scavenging activity and ORAC than EP-1, with the exception of DPPH-scavenging activity. Antioxidant activities of these extracts were further studied using hydrogen peroxide (H2O2-abused GES-1 cells; EP-1 dose-dependently preserved cell viability of abused cells as assessed via MTT assay. Moreover, FACS analysis revealed that EP-1 prevented H2O2-induced apoptotic cell death by inhibiting activation of apoptotic cellular signals within mitochondria-dependent apoptotic pathways. CMPS also prevented H2O2-induced oxidative stress, but to a lesser degree than did EP-1, even though CMPS exhibited comparable or stronger in vitro antioxidant activity than did EP-1.

  4. Changes of Nitric Oxide and Its Relationship with H2O2 and Ca2+ in Defense Interactions between Wheat and Puccinia Triticina.

    Directory of Open Access Journals (Sweden)

    Mei Qiao

    Full Text Available In this research, the wheat cultivar 'Lovrin 10' and Puccinia triticina races 165 and 260 were used to constitute compatible and incompatible combinations to investigate the relationship between NO and H2O2 and between NO and calcium (Ca(2+ signaling in the cell defense process by pharmacological means. The specific fluorescent probe DAF-FM DA was coupled with confocal laser scanning microscopy and used to label intracellular nitric oxide (NO and monitoring the real-time NO dynamics during the processes of wheat defense response triggered by P. triticina infection. The results showed that at 4 h after inoculation, weak green fluorescence was observed in the stomatal guard cells at the P. triticina infection site in the incompatible combination, which indicates a small amount of NO production. Twelve hours after inoculation, the fluorescence of NO in- cell adjacent to the stomata gradually intensified, and the NO fluorescent area also expanded continuously; the green fluorescence primarily occurred in the cells undergoing a hypersensitive response (HR at 24-72 h after inoculation. For the compatible combination, however, a small amount of green fluorescence was observed in stomata where the pathogenic contact occurred at 4 h after inoculation, and fluorescence was not observed thereafter. Injections of the NO scavenger c-PTIO prior to inoculation postponed the onset of NO production to 48 h after inoculation and suppressed HR advancement. The injection of imidazole, a NADPH oxidase inhibitor, or EGTA, an extracellular calcium chelator, in the leaves prior to inoculation, delayed the onset of NO production in the incompatible combination and suppressed HR advancement. Combined with our previous results, it could be concluded that, Ca(2+ and hydrogen peroxide (H2O2 are involved in upstream of NO production to induce the HR cell death during P. triticina infection, and Ca(2+, NO and H2O2 are jointly involved in the signal transduction process of HR

  5. Repairable and nonrepairable inactivation of irradiated aqueous papain: effect of OH, O2-, e/sub aq-/, and H2O2

    International Nuclear Information System (INIS)

    Lin, W.S.; Clement, J.R.; Gaucher, G.M.; Armstrong, D.A.

    1975-01-01

    Repairable inactivation of papain irradiated in dilute aqueous solutions saturated with air or nitrous oxide is caused predominantly by reversible oxidation of Cys 25 SH by H 2 O 2 . The same process occurs in nitrogen-saturated solutions but the yield of repairable product decreases at higher doses, probably because of the consumption of H 2 O 2 by intermediates formed from e - /sub aq/ and papain. The OH radical produces only nonrepairable damage, with the fraction of the OH radical causing nonrepairable inactivation (f/sub OH//sup n.r./) equal to 0.1 and this is accompanied by, if not solely due to, SH loss. The O 2 - radical with f/sub O 2 //sup -n.r. = 0.4 also causes nonrepairable damage resulting from or accompanied by SH loss. In addition, there is evidence that every O 2 - reacts with papain to produce a hydrogen peroxide molecule, thus causing a marked increase in the repairable yield. The solvated electron for which f/sub e//Sup n.r./ is 0.07 does not appear to destroy Cys 25 SH, and must, therefore, inactivate papain by damaging other essential residues or changing the active site geometry. The inactivation yields for the present papain solutions prepared by affinity chromatography are compared with other work. Discrepancies in previous determinations of sulfhydryl loss are attributed to the special properties of the sulfenic acid product of the H 2 O 2 -papain reaction and its different effects on pHMB and DTNB assays. (U.S.)

  6. H2-O2 supercritical combustion modeling using a CFD code

    Directory of Open Access Journals (Sweden)

    Benarous Abdallah

    2009-01-01

    Full Text Available The characteristics of propellant injection, mixing, and combustion have a profound effect on liquid rocket engine performance. The necessity of raising rocket engines performance requires a combustion chamber operation often in a supercritical regime. A supercritical combustion model based on a one-phase multi-components approach is developed and tested on a non-premixed H2-O2 flame configuration. A two equations turbulence model is used for describing the jet dynamics where a limited Pope correction is added to account for the oxidant spreading rate. Transport properties of the mixture are calculated using extended high pressure forms of the mixing rules. An equilibrium chemistry scheme is adopted in this combustion case, with both algebraic and stochastic expressions for the chemistry/turbulence coupling. The model was incorporated into a computational fluid dynamics commercial code (Fluent 6.2.16. The validity of the present model was investigated by comparing predictions of temperature, species mass fractions, recirculation zones and visible flame length to the experimental data measured on the Mascotte test rig. The results were confronted also with advanced code simulations. It appears that the agreement between the results was fairly good in the chamber regions situated downstream the near injection zone.

  7. Particle Sampling and Real Time Size Distribution Measurement in H2/O2/TEOS Diffusion Flame

    International Nuclear Information System (INIS)

    Ahn, K.H.; Jung, C.H.; Choi, M.; Lee, J.S.

    2001-01-01

    Growth characteristics of silica particles have been studied experimentally using in situ particle sampling technique from H 2 /O 2 /Tetraethylorthosilicate (TEOS) diffusion flame with carefully devised sampling probe. The particle morphology and the size comparisons are made between the particles sampled by the local thermophoretic method from the inside of the flame and by the electrostatic collector sampling method after the dilution sampling probe. The Transmission Electron Microscope (TEM) image processed data of these two sampling techniques are compared with Scanning Mobility Particle Sizer (SMPS) measurement. TEM image analysis of two sampling methods showed a good agreement with SMPS measurement. The effects of flame conditions and TEOS flow rates on silica particle size distributions are also investigated using the new particle dilution sampling probe. It is found that the particle size distribution characteristics and morphology are mostly governed by the coagulation process and sintering process in the flame. As the flame temperature increases, the effect of coalescence or sintering becomes an important particle growth mechanism which reduces the coagulation process. However, if the flame temperature is not high enough to sinter the aggregated particles then the coagulation process is a dominant particle growth mechanism. In a certain flame condition a secondary particle formation is observed which results in a bimodal particle size distribution

  8. Application of UV/TiO2/H2O2 Advanced Oxidation to Remove Naphthalene from Water

    Directory of Open Access Journals (Sweden)

    Behroz Karimi

    2016-11-01

    Full Text Available Naphthalene is released into the environment by burning such organic materials as fossil fuels and wood and in industrial and vehicle exhaust emissions. Naphthalene is used in the manufacture of plastics, resins, fuels, and dyes. The aim of this study was to evaluate the performance of UV/TiO2/H2O2 process to decompose naphthalene in aqueous solutions. For this purpose, the photocatalytic degradation of naphthalene was investigated under UV light irradiation in the presence of TiO2 and H2O2 under a variety of conditions. Photodegradation efficiencies of H2O2/UV, TiO2/UV, and H2O2/TiO2/UV processes were compared in a batch reactor using the low pressure mercury lamp irradiation. The effects of operating parameters such as reaction time (min; solution pH; and initial naphthalene, TiO2, and H2O2 concentrations on photodegradation were examined. In the UV/TiO2/H2O2 system with a naphthalene concentration of 15 mg/L, naphthalene removal efficiencies of 63, 75, 80, 88, 92, 95, 96.5, and 98% were achieved, respectively, for reaction times of 5, 10, 20, 30, 40, 50, 60, 100 and 120 min. This is while removal efficienciesof 50, 59.5, 69, 80, 85, 88, 91, and 95% were obtained in the UV/TiO2 system under the same conditions. For initial pH values of 3, 4, 5, 6, 7,9, 10, and 12, naphthalene removal efficiencies of approximately 96.8, 85.5, 86, 75.5, 68.8, 57.8, and 52.5% were acheived, respectively, with the UV/TiO2/H2O2 system. Thus, it may be claiomed that, compared to either H2O2/UV or TiO2/UV process, the H2O2/TiO2/UV process yielded a far more efficient photodegradation.

  9. Synergistic Effect of H2O2 and NO2 in Cell Death Induced by Cold Atmospheric He Plasma

    Science.gov (United States)

    Girard, Pierre-Marie; Arbabian, Atousa; Fleury, Michel; Bauville, Gérard; Puech, Vincent; Dutreix, Marie; Sousa, João Santos

    2016-01-01

    Cold atmospheric pressure plasmas (CAPPs) have emerged over the last decade as a new promising therapy to fight cancer. CAPPs’ antitumor activity is primarily due to the delivery of reactive oxygen and nitrogen species (RONS), but the precise determination of the constituents linked to this anticancer process remains to be done. In the present study, using a micro-plasma jet produced in helium (He), we demonstrate that the concentration of H2O2, NO2− and NO3− can fully account for the majority of RONS produced in plasma-activated buffer. The role of these species on the viability of normal and tumour cell lines was investigated. Although the degree of sensitivity to H2O2 is cell-type dependent, we show that H2O2 alone cannot account for the toxicity of He plasma. Indeed, NO2−, but not NO3−, acts in synergy with H2O2 to enhance cell death in normal and tumour cell lines to a level similar to that observed after plasma treatment. Our findings suggest that the efficiency of plasma treatment strongly depends on the combination of H2O2 and NO2− in determined concentrations. We also show that the interaction of the He plasma jet with the ambient air is required to generate NO2− and NO3− in solution. PMID:27364563

  10. Electrocatalytic activity of LaNiO3 toward H2O2 reduction reaction: Minimization of oxygen evolution

    Science.gov (United States)

    Amirfakhri, Seyed Javad; Meunier, Jean-Luc; Berk, Dimitrios

    2014-12-01

    The catalytic activity of LaNiO3 toward H2O2 reduction reaction (HPRR), with a potential application in the cathode side of fuel cells, is studied in alkaline, neutral and acidic solutions by rotating disk electrode. The LaNiO3 particles synthesised by citrate-based sol-gel method have sizes between 30 and 70 nm with an active specific surface area of 1.26 ± 0.05 m2 g-1. LaNiO3 shows high catalytic activity toward HPRR in 0.1 M KOH solution with an exchange current density based on the active surface area (j0A) of (7.4 ± 1) × 10-6 A cm-2 which is noticeably higher than the j0A of N-doped graphene. The analysis of kinetic parameters suggests that the direct reduction of H2O2, H2O2 decomposition, O2 reduction and O2 desorption occur through HPRR on this catalyst. In order to control and minimize oxygen evolution from the electrode surface, the effects of catalyst loading, bulk concentration of H2O2, and using a mixture of LaNiO3 and N-doped graphene are studied. Although the mechanism of HPRR is independent of the aforementioned operating conditions, gas evolution decreases by increasing the catalyst loading, decreasing the bulk concentration of H2O2, and addition of N-doped graphene to LaNiO3.

  11. Tumor cells have decreased ability to metabolize H2O2: Implications for pharmacological ascorbate in cancer therapy

    Directory of Open Access Journals (Sweden)

    Claire M. Doskey

    2016-12-01

    Full Text Available Ascorbate (AscH− functions as a versatile reducing agent. At pharmacological doses (P-AscH−; [plasma AscH−] ≥≈20 mM, achievable through intravenous delivery, oxidation of P-AscH− can produce a high flux of H2O2 in tumors. Catalase is the major enzyme for detoxifying high concentrations of H2O2. We hypothesize that sensitivity of tumor cells to P-AscH− compared to normal cells is due to their lower capacity to metabolize H2O2. Rate constants for removal of H2O2 (kcell and catalase activities were determined for 15 tumor and 10 normal cell lines of various tissue types. A differential in the capacity of cells to remove H2O2 was revealed, with the average kcell for normal cells being twice that of tumor cells. The ED50 (50% clonogenic survival of P-AscH− correlated directly with kcell and catalase activity. Catalase activity could present a promising indicator of which tumors may respond to P-AscH−.

  12. Determination of selenium via the fluorescence quenching effect of selenium on hemoglobin-catalyzed peroxidative reaction.

    Science.gov (United States)

    Chen, Ya-Hong; Zhang, Ya-Nan; Tian, Feng-Shou

    2015-05-01

    A new method for the determination of selenium based on its fluorescence quenching on the hemoglobin-catalyzed reaction of H2 O2 and l-tyrosine has been established. The effect of pH, foreign ions and the optimization of variables on the determination of selenium was examined. The calibration curve was found to be linear between the fluorescence quenching (F0 /F) and the concentration of selenium within the range of 0.16-4.00 µg/mL. The detection limit was 1.96 ng/mL and the relative standard deviation was 3.14%. This method can be used for the determination of selenium in Se-enriched garlic bulbs with satisfactory results. Copyright © 2014 John Wiley & Sons, Ltd.

  13. Removal of diethyl phthalate from water solution by adsorption, photo-oxidation, ozonation and advanced oxidation process (UV/H2O2, O3/H2O2 and O3/activated carbon)

    International Nuclear Information System (INIS)

    Medellin-Castillo, Nahum A.; Ocampo-Pérez, Raúl; Leyva-Ramos, Roberto; Sanchez-Polo, Manuel; Rivera-Utrilla, José; Méndez-Díaz, José D.

    2013-01-01

    The objective of this work was to compare the effectiveness of conventional technologies (adsorption on activated carbon, AC, and ozonation) and technologies based on advanced oxidation processes, AOPs, (UV/H 2 O 2 , O 3 /AC, O 3 /H 2 O 2 ) to remove phthalates from aqueous solution (ultrapure water, surface water and wastewater). Diethyl phthalate (DEP) was chosen as a model pollutant because of its high water solubility (1080 mg/L at 293 K) and toxicity. The activated carbons showed a high adsorption capacity to adsorb DEP in aqueous solution (up to 858 mg/g), besides the adsorption mechanism of DEP on activated carbon is governed by dispersive interactions between π electrons of its aromatic ring with π electrons of the carbon graphene planes. The photodegration process showed that the pH solution does not significantly affect the degradation kinetics of DEP and the first-order kinetic model satisfactorily fitted the experimental data. It was observed that the rate of decomposition of DEP with the O 3 /H 2 O 2 and O 3 /AC systems is faster than that with only O 3 . The technologies based on AOPs (UV/H 2 O 2 , O 3 /H 2 O 2 , O 3 /AC) significantly improve the degradation of DEP compared to conventional technologies (O 3 , UV). AC adsorption, UV/H 2 O 2 , O 3 /H 2 O 2 , and O 3 /AC showed a high yield to remove DEP; however, the disadvantage of AC adsorption is its much longer time to reach maximum removal. The best system to treat water (ultrapure and natural) polluted with DEP is the O 3 /AC one since it achieved the highest DEP degradation and TOC removal, as well as the lower water toxicity. -- Highlights: ► Activated carbons showed a high adsorption capacity (up to 858 mg/g) to remove DEP. ► The pH solution did not significantly affect the photodegradation kinetics of DEP. ► The O 3 /H 2 O 2 and O 3 /AC systems were more efficient than O 3 to degrade DEP. ► The generation of HO • from O 3 was enhanced by ACs, mainly by those of basic nature. ► O

  14. Preconditioning with Gua Lou Gui Zhi decoction enhances H2O2-induced Nrf2/HO-1 activation in PC12 cells

    Science.gov (United States)

    MAO, JINGJIE; LI, ZUANFANG; LIN, RUHUI; ZHU, XIAOQIN; LIN, JIUMAO; PENG, JUN; CHEN, LIDIAN

    2015-01-01

    Spasticity is common in various central neurological conditions, including after a stroke. Such spasticity may cause additional problems, and often becomes a primary concern for afflicted individuals. A number of studies have identified nuclear factor (erythroid-derived 2)-like 2 (Nrf2) as a key regulator in the adaptive survival response to oxidative stress. Elevated expression of Nrf2, combined with heme oxygenase 1 (HO-1) resistance, in the central nervous system is known to elicit key internal and external oxidation protection. Gua Lou Gui Zhi decoction (GLGZD) is a popular traditional Chinese formula with a long history of clinical use in China for the treatment of muscular spasticity following a stroke, epilepsy or a spinal cord injury. However, the mechanism underlying the efficacy of the medicine remains unclear. In the present study, the antioxidative effects of GLGZD were evaluated and the underlying molecular mechanisms were investigated, using hydrogen peroxide (H2O2)-induced rat pheochromocytoma cells (PC12 cells) as an in vitro oxidative stress model of neural cells. Upon application of different concentrations of GLGZD, a 3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyltetrazolium bromide (MTT) assay and ATP measurement were conducted to assess the impact on PC12 cell proliferation. In addition, inverted microscopy observations, and the MTT and ATP assessments, revealed that GLGZD attenuated H2O2-induced oxidative damage and signaling repression in PC12 cells. Furthermore, the mRNA and protein expression levels of Nrf2 and HO-1, which are associated with oxidative stress, were analyzed using reverse transcription quantitative polymerase chain reaction (PCR) and confocal microscopy. Confocal microscopy observations, as well as the quantitative PCR assay, revealed that GLGZD exerted a neuroprotective function against H2O2-induced oxidative damage in PC12 cells. Therefore, the results demonstrated that GLGZD protected PC12 cells injured by H2O2, which may be

  15. Degradation of sulfamethoxazole by UV, UV/H2O2 and UV/persulfate (PDS): Formation of oxidation products and effect of bicarbonate.

    Science.gov (United States)

    Yang, Yi; Lu, Xinglin; Jiang, Jin; Ma, Jun; Liu, Guanqi; Cao, Ying; Liu, Weili; Li, Juan; Pang, Suyan; Kong, Xiujuan; Luo, Congwei

    2017-07-01

    The frequent detection of sulfamethoxazole (SMX) in wastewater and surface waters gives rise of concerns about their ecotoxicological effects and potential risks to induce antibacterial resistant genes. UV/hydrogen peroxide (UV/H 2 O 2 ) and UV/persulfate (UV/PDS) advanced oxidation processes have been demonstrated to be effective for the elimination of SMX, but there is still a need for a deeper understanding of product formations. In this study, we identified and compared the transformation products of SMX in UV, UV/H 2 O 2 and UV/PDS processes. Because of the electrophilic nature of SO 4 - , the second-order rate constant for the reaction of sulfate radical (SO 4 - ) with the anionic form of SMX was higher than that with the neutral form, while hydroxyl radical (OH) exhibited comparable reactivity to both forms. The direct photolysis of SMX predominately occurred through cleavage of the NS bond, rearrangement of the isoxazole ring, and hydroxylation mechanisms. Hydroxylation was the dominant pathway for the reaction of OH with SMX. SO 4 - favored attack on NH 2 group of SMX to generate a nitro derivative and dimeric products. The presence of bicarbonate in UV/H 2 O 2 inhibited the formation of hydroxylated products, but promoted the formation of the nitro derivative and the dimeric products. In UV/PDS, bicarbonate increased the formation of the nitro derivative and the dimeric products, but decreased the formation of the hydroxylated dimeric products. The different effect of bicarbonate on transformation products in UV/H 2 O 2 vs. UV/PDS suggested that carbonate radical (CO 3 - ) oxidized SMX through the electron transfer mechanism similar to SO 4 - but with less oxidation capacity. Additionally, SO 4 - and CO 3 - exhibited higher reactivity to the oxazole ring than the isoxazole ring of SMX. Ecotoxicity of transformation products was estimated by ECOSAR program based on the quantitative structure-activity relationship analysis as well as by experiments using

  16. Bradykinin-potentiating PEPTIDE-10C, an argininosuccinate synthetase activator, protects against H2O2-induced oxidative stress in SH-SY5Y neuroblastoma cells.

    Science.gov (United States)

    Querobino, Samyr Machado; Ribeiro, César Augusto João; Alberto-Silva, Carlos

    2018-05-01

    Bradykinin-potentiating peptides (BPPs - 5a, 7a, 9a, 10c, 11e, and 12b) of Bothrops jararaca (Bj) were described as argininosuccinate synthase (AsS) activators, improving l-arginine availability. Agmatine and polyamines, which are l-arginine metabolism products, have neuroprotective properties. Here, we investigated the neuroprotective effects of low molecular mass fraction from Bj venom (LMMF) and two synthetic BPPs (BPP-10c, BPP-12b, BPP-10c showed higher protective capacity than BPP-12b. LMMF pretreatment was unable to prevent the reduction of cell viability caused by H 2 O 2 . The neuroprotective mechanism of BPP-10c against oxidative stress was investigated. BPP-10c reduced ROS generation and lipid peroxidation in relation to cells treated only with H 2 O 2 . BBP-10c increased AsS expression and was not neuroprotective in the presence of MDLA, a specific inhibitor of AsS. BPP-10c reduced iNOS expression and nitrate levels but decreased NF-kB expression. Furthermore, BPP-10c protected the mitochondrial membrane against oxidation. Overall, we demonstrated for the first time neuroprotective mechanisms of BPPs against oxidative stress, opening new perspectives to the study and application of these peptides for the treatment of neurodegenerative diseases. Copyright © 2018 Elsevier Inc. All rights reserved.

  17. Extracts from Calendula officinalis offer in vitro protection against H2 O2 induced oxidative stress cell killing of human skin cells.

    Science.gov (United States)

    Alnuqaydan, Abdullah M; Lenehan, Claire E; Hughes, Rachel R; Sanderson, Barbara J

    2015-01-01

    The in vitro safety and antioxidant potential of Calendula officinalis flower head extracts was investigated. The effect of different concentrations (0.125, 0.5, 1.0, 2.0 and 5.0% (v/v)) of Calendula extracts on human skin cells HaCaT in vitro was explored. Doses of 1.0% (v/v) (0.88 mg dry weight/mL) or less showed no toxicity. Cells were also exposed to the Calendula extracts for either 4, 24 or 48 h before being exposed to an oxidative insult (hydrogen peroxide H2 O2 ) for 1 h. Using the MTT cytotoxicity assay, it was observed that two independent extracts of C. officinalis gave time-dependent and concentration-dependent H2 O2 protection against induced oxidative stress in vitro using human skin cells. Pre-incubation with the Calendula extracts for 24 and 48 h increased survival relative to the population without extract by 20% and 40% respectively following oxidative challenge. The antioxidant potential of the Calendula extracts was confirmed using a complimentary chemical technique, the DPPH(●) assay. Calendula extracts exhibited free radical scavenging abilities. This study demonstrates that Calendula flower extracts contain bioactive and free radical scavenging compounds that significantly protect against oxidative stress in a human skin cell culture model. Copyright © 2014 John Wiley & Sons, Ltd.

  18. Tungsten-Based Mesoporous Silicates W-MMM-E as Heterogeneous Catalysts for Liquid-Phase Oxidations with Aqueous H2O2

    Directory of Open Access Journals (Sweden)

    Nataliya Maksimchuk

    2018-02-01

    Full Text Available Mesoporous tungsten-silicates, W-MMM-E, have been prepared following evaporation-induced self-assembly methodology and characterized by elemental analysis, XRD, N2 adsorption, STEM-HAADF (high angle annular dark field in scanning-TEM mode, DRS UV-vis, and Raman techniques. DRS UV-vis showed the presence of two types of tungsten oxo-species in W-MMM-E samples: isolated tetrahedrally and oligomeric octahedrally coordinated ones, with the ratio depending on the content of tungsten in the catalyst. Materials with lower W loading have a higher contribution from isolated species, regardless of the preparation method. W-MMM-E catalyzes selectively oxidize of a range of alkenes and organic sulfides, including bulky terpene or thianthrene molecules, using green aqueous H2O2. The selectivity of corresponding epoxides reached 85–99% in up to 80% alkene conversions, while sulfoxides formed with 84–90% selectivity in almost complete sulfide conversions and a 90–100% H2O2 utilization efficiency. The true heterogeneity of catalysis over W-MMM-E was proved by hot filtration tests. Leaching of inactive W species depended on the reaction conditions and initial W loading in the catalyst. After optimization of the catalyst system, it did not exceed 20 ppm and 3 ppm for epoxidation and sulfoxidation reactions, respectively. Elaborated catalysts could be easily retrieved by filtration and reused several times with maintenance of the catalytic behavior.

  19. Upper limits for stratospheric H2O2 and HOCl from high resolution balloon-borne infrared solar absorption spectra

    Science.gov (United States)

    Larsen, J. C.; Rinsland, C. P.; Goldman, A.; Murcray, D. G.; Murcray, F. J.

    1985-01-01

    Solar absorption spectra from two stratospheric balloon flights have been analyzed for the presence of H2O2 and HOCl absorption in the 1230.0 to 1255.0 per cm region. The data were recorded at 0.02 per cm resolution during sunset with the University of Denver interferometer system on October 27, 1978 and March 23, 1981. Selected spectral regions were analyzed with the technique of nonlinear least squares spectral curve fitting. Upper limits of 0.33 ppbv for H2O2 and 0.36 ppbv for HOCl near 28 km are derived from the 1978 flight data while upper limits of 0.44 ppbv for H2O2 and 0.43 ppbv for HOCl at 29.5 km are obtained from the 1981 flight data.

  20. Degradation of Organophosphorus Pesticides in Water during UV/H2O2 Treatment: Role of Sulphate and Bicarbonate Ions

    Directory of Open Access Journals (Sweden)

    Am Fadaei

    2012-01-01

    Full Text Available The photodegradation of two organophosphorus pesticides, malathian and diazinon, by sulfate radicals and bicarbonate radicals in aqueous solution were studied. The effect of the operational parameters such as pH, salt concentration, water type, H2O2 concentration and initial concentration of pesticides was studied. Gas chromatography mass spectroscopy (GC–MS was used for analyses of pesticides. When salt effect was studied, it was found that sodium bicarbonate was the most powerful inhibitor used, while sodium sulfate was the weakest one. The highest degradation in UV/H2O2 process for malathion was found in alkaline condition and for diazinon in acidic condition. The photodegradation in all waters used in this work exhibited first order kinetics. Photodegradation rate in distilled water was higher than real water. The degradation of pesticides increased with increasing of H2O2 concentration.

  1. Degradation kinetics of reactive dye by UV/H2O2/US process under continuous mode operation.

    Science.gov (United States)

    Fung, P C; Poon, C S; Chu, C W; Tsui, S M

    2001-01-01

    Degradation of a dye, C. I . Reactive Red 120, in dyeing waatewater by the process o UV/H2O2/US was studied with a bench-scale reactor under the continuous mode of operation. The effects of dyeing wastewater flow rate and the feeding rate of an oxidant, H2O2, on the color removal efficiency of the process were investigated. The significance of ultrasonic (US) combined with UV irradiation was also investigated and the performances of the process on color removal were evaluated. The results showed that the decoloration process followed a pseudo first-order kinetic model and the UV light is the most significant factor on dye removal. Besides, at higher flow rates, incomplete color removal was observed due to relatively insufficient irradiation time (low degradation rate). In order to achieve a higher degradation rate, the feeding rate of H2O2 should be increased.

  2. Sorption of diclofenac and naproxen onto MWCNT in model wastewater treated by H2O2 and/or UV.

    Science.gov (United States)

    Czech, Bożena; Oleszczuk, Patryk

    2016-04-01

    The application of oxidation processes such as UV and/or H2O2 will change the physicochemical properties of carbon nanotubes (CNT). It may affect the sorption affinity of CNT to different contaminants and then affect their fate in the environment. In the present study the adsorption of two very common used pharmaceuticals (diclofenac and naproxen) onto CNT treated by UV, H2O2 or UV/H2O2 was investigated. Four different adsorption models (Freundlich, Langmuir, Temkin, Dubinin-Radushkevich) were tested. The best fitting of experimental data was observed for Freundlich or Langmuir model. The significant relationships between Q calculated from Langmuir model with O% and dispersity were observed. Kinetics of diclofenac and naproxen followed mainly pseudo-second order indicating for chemisorption limiting step of adsorption. The data showed that the mechanism of sorption was physical or chemical depending on the type of CNT modification. Copyright © 2015 Elsevier Ltd. All rights reserved.

  3. A H2O2 Biosensor Based on Immobilization of HorseradishPeroxidase in a Gelatine Network Matrix

    Directory of Open Access Journals (Sweden)

    Jun-Jie Zhu

    2005-05-01

    Full Text Available A simple and promising H2O2 biosensor has been developed by successfulentrapment of horseradish peroxidase (HRP in a gelatine matrix which was cross-linkedwith formaldehyde. The large microscopic surface area and porous morphology of thegelatine matrix lead to high enzyme loading and the enzyme entrapped in this matrix canretain its bioactivity. This biosensor exhibited a fast amperometric response to hydrogenperoxide (H2O2. The linear range for H2O2 determination was from 2.5×10-5 to2.5×10-3 M, with a detection limit of 2.0×10-6 M based on S / N = 3. This biosensorpossessed very good reproducibility.

  4. Removal of organic matter and ammoniacal nitrogen from landfill leachate using the UV/H2O2 photochemical process.

    Science.gov (United States)

    Córdova, Rolando Nunes; Nagel-Hassemer, Maria Eliza; Matias, William Gerson; Muller, Jose Miguel; de Castilhos Junior, Armando Borges

    2017-12-04

    This study investigates the effects of pH, H 2 O 2 concentration and reaction time of the UV/H 2 O 2 photochemical process on the removal of organic matter and ammonia from biologically pre-treated landfill leachates in anaerobic stabilization ponds. The results show that the concentration of H 2 O 2 and the initial pH are significant factors, with no significant interaction between them. A pH of 3 is the optimum value for the UV/H 2 O 2 process for the removal of organic matter, resulting in 51.63% chemical oxygen demand (COD) removal in addition to the removal of aromatic compounds. The N-NH 3 removal showed little variation between pH values of 1, 5, 7, 11 and 13; the removal was on the order of 16.43 ± 2.00%. The consumption of H 2 O 2 was elevated at pH 9, 11 and 13; at these pH values, the average removal was 94.56 ± 0.43%, compared to 43.07% at pH 3. First-order polynomial models and reaction times on the order of 15 min are sufficient for optimization studies and for evaluation of the effects of the studied parameters. The results of this study support the optimization of the UV/H 2 O 2 process for the removal of organic matter and ammonia from landfill leachates.

  5. Graphitic Carbon Nitride Nanosheets-Based Ratiometric Fluorescent Probe for Highly Sensitive Detection of H2O2 and Glucose.

    Science.gov (United States)

    Liu, Jin-Wen; Luo, Ying; Wang, Yu-Min; Duan, Lu-Ying; Jiang, Jian-Hui; Yu, Ru-Qin

    2016-12-14

    Graphitic carbon nitride (g-C 3 N 4 ) nanosheets, an emerging graphene-like carbon-based nanomaterial with high fluorescence and large specific surface areas, hold great potential for biosensor applications. Current g-C 3 N 4 nanosheets based fluorescent biosensors majorly rely on single fluorescent intensity reading through fluorescence quenching interactions between the nanosheets and metal ions. Here we report for the first time the development of a novel g-C 3 N 4 nanosheets-based ratiometric fluorescence sensing strategy for highly sensitive detection of H 2 O 2 and glucose. With o-phenylenediamine (OPD) oxidized by H 2 O 2 in the presence of horseradish peroxidase (HRP), the oxidization product can assemble on the g-C 3 N 4 nanosheets through hydrogen bonding and π-π stacking, which effectively quenches the fluorescence of g-C 3 N 4 while delivering a new emission peak. The ratiometric signal variations enable robust and sensitive detection of H 2 O 2 . On the basis of the glucose converting into H 2 O 2 through the catalysis of glucose oxidase, the g-C 3 N 4 -based ratiometric fluorescence sensing platform is also exploited for glucose assay. The developed strategy is demonstrated to give a detection limit of 50 nM for H 2 O 2 and 0.4 μM for glucose, at the same time, it has been successfully used for glucose levels detection in human serum. This strategy may provide a cost-efficient, robust, and high-throughput platform for detecting various species involving H 2 O 2 -generation reactions for biomedical applications.

  6. Effects of different activation processes on H2O2/TAED bleaching of Populus nigra chemi-thermo mechanical pulp

    OpenAIRE

    Qiang Zhao; Dezhi Sun; Zhaohong Wang; Junwen Pu; Xiaojuan Jin; Mian Xing

    2012-01-01

    Tetra acetyl ethylene diamine (TAED) was used as an activator in H2O2 bleaching to improve bleaching efficiency. The present work was aimed at confirming different activations for various H2O2/TAED bleaching processes, including the addition of acetic anhydride and the step-addition of sodium hydroxide. The results showed that an acetic anhydride dosage of 1%, an acetic anhydride treatment time of 10 min, and an addition time of 45 min were the optimal treatment conditions. The optimum proces...

  7. A model for radiolysis of water and aqueous solutions of H2, H2O2 and O2

    International Nuclear Information System (INIS)

    Ershov, B.G.; Gordeev, A.V.

    2008-01-01

    Kinetic model for the radiolysis of pure water describing the formation of H 2 , H 2 O 2 and O 2 and the radiation chemical transformations of aqueous solutions containing these compounds over a broad range of concentrations, pH, absorbed doses and dose rates is proposed and substantiated. The model includes a set of chemical reactions with optimized rate constants and the radiation chemical yields of radiolysis products. The model applicability to the description of the whole set of data on the radiation chemical transformations of water and aqueous solutions of H 2 , H 2 O 2 and O 2 is demonstrated

  8. Detection of γ-irradiation of foods. Use of H2O2-stimulated and photostimulated chemiluminescence. Pt. 1

    International Nuclear Information System (INIS)

    Lewin, G.; Popov, I.N.; Schreiber, G.A.; Helle, N.

    1993-01-01

    Beside methods for unequivocal identification of irradiation treatment of food screening methods which do not always give a final answer are needed for an effective control. In this paper preliminary results are presented which were obtained by measurement of the H 2 O 2 -stimulated and photostimulated chemiluminescence of apples treated by ionising radiation. Appels were chosen as a model for fresh fruit and vegetables. It seems that the H 2 O 2 -stimulated chemiluminescence can be used to screen fruit and vegetables to detect irradiation treatment. (orig.) [de

  9. KECK II OBSERVATIONS OF HEMISPHERICAL DIFFERENCES IN H2O2 ON EUROPA

    International Nuclear Information System (INIS)

    Hand, K. P.; Brown, M. E.

    2013-01-01

    We present results from Keck II observations of Europa over four consecutive nights using the near-infrared spectrograph. Spectra were collected in the 3.14-4.0 μm range, enabling detection and monitoring of the 3.5 μm feature due to hydrogen peroxide. Galileo Near-Infrared Mapping Spectrometer results first revealed hydrogen peroxide on Europa in the anti-Jovian region of the leading hemisphere at a percent by number abundance of 0.13% ± 0.07% relative to water. We find comparable results for the two nights over which we observed the leading hemisphere. Significantly, we observed a small amount of hydrogen peroxide (∼0.04%) during observations of Europa's anti-Jovian and sub-Jovian hemispheres. Almost no hydrogen peroxide was detected during observations of just the trailing hemisphere. We conclude that the Galileo observations likely represent the maximum hydrogen peroxide concentration, the exception potentially being the cold water ice regions of the poles, which are not readily observable from the ground. Our mapping of the peroxide abundance across Europa requires revisions to previous estimates for Europa's global surface abundance of oxidants and leads to a reduction in the total oxidant delivery expected for the subsurface ocean if an exchange of surface material with the ocean occurs.

  10. A Coupled Soil-Atmosphere Model of H2O2 on Mars

    Science.gov (United States)

    Bullock, Mark A.; Stoker, Carol R.; Mckay, Christopher P.; Zent, Aaron P.

    1994-01-01

    The Viking Gas Chromatograph Mass Spectrometer failed to detect organic compounds on Mars, and both the Viking Labeled Release and the Viking Gas Exchange experiments indicated a reactive soil surface. These results have led to the widespread belief that there are oxidants in the martian soil. Since H2O2 is produced by photochemical processes in the atmosphere of Mars, and has been shown in the laboratory to reproduce closely the Viking LR results, it is a likely candidate for a martian soil oxidant. Here, we report on the results of a coupled soil/atmosphere transport model for H202 on Mars. Upon diffusing into the soil, its concentration is determined by the extent to which it is adsorbed and by the rate at which it is catalytically destroyed. An analytical model for calculating the distribution of H202 in the martian atmosphere and soil is developed. The concentration of H202 in the soil is shown to go to zero at a finite depth, a consequence of the nonlinear soil diffusion equation. The model is parameterized in terms of an unknown quantity, the lifetime of H202 against heterogeneous catalytic destruction in the soil. Calculated concentrations are compared with a H202 concentration of 30 nmoles/cu cm, inferred from the Viking Labeled Release experiment. A significant result of this model is that for a wide range of H202 lifetimes (up to 105 years), the extinction depth was found to be less than 3 m. The maximum possible concentration in the top 4 cm is calculated to be approx. 240 nmoles/cu cm, achieved with lifetimes of greater than 1000 years. Concentrations higher than 30 nmoles/cu cm require lifetimes of greater than 4.3 terrestrial years. For a wide range of H202 lifetimes, it was found that the atmospheric concentration is only weakly coupled with soil loss processes. Losses to the soil become significant only when lifetimes are less than a few hours. If there are depths below which H202 is not transported, it is plausible that organic compounds

  11. A lysosome-locating and acidic pH-activatable fluorescent probe for visualizing endogenous H2O2 in lysosomes.

    Science.gov (United States)

    Liu, Jun; Zhou, Shunqing; Ren, Jing; Wu, Chuanliu; Zhao, Yibing

    2017-11-20

    There is increasing evidence indicating that lysosomal H 2 O 2 is closely related to autophagy and apoptotic pathways under both physiological and pathological conditions. Therefore, fluorescent probes that can be exploited to visualize H 2 O 2 in lysosomes are potential tools for exploring diverse roles of H 2 O 2 in cells. However, functional exploration of lysosomal H 2 O 2 is limited by the lack of fluorescent probes capable of compatibly sensing H 2 O 2 under weak acidic conditions (pH = 4.5) of lysosomes. Lower spatial resolution of the fluorescent visualization of lysosomal H 2 O 2 might be caused by the interference of signals from cytosolic and mitochondrial H 2 O 2 , as well as the non-specific distribution of the probes in cells. In this work, we developed a lysosome-locating and acidic-pH-activatable fluorescent probe for the detection and visualization of H 2 O 2 in lysosomes, which consists of a H 2 O 2 -responsive boronate unit, a lysosome-locating morpholine group, and a pH-activatable benzorhodol fluorophore. The response of the fluorescent probe to H 2 O 2 is significantly more pronounced under acidic pH conditions than that under neutral pH conditions. Notably, the present probe enables the fluorescence sensing of endogenous lysosomal H 2 O 2 in living cells without external stimulations, with signal interference from the cytoplasm and other intracellular organelles being negligible.

  12. Sorption behaviour of W, Hf, Lu, U, and Th on ion exchangers from HCl/H2O2 solutions. Model experiments for chemical studies of seaborgium (Sg)

    International Nuclear Information System (INIS)

    Schumann, D.; Andrassy, M.; Nitsche, H.; Misiak, R.; Schaedel, M.; Bruechle, W.; Schausten, B.; Kratz, J.V.

    1997-08-01

    In model experiments with W, Hf, Th, and U radionuclides, a chemical system was developed for the separation of seaborgium from element 104 and heavy actinides, i.e., cation exchange on DOWEX 50 x 8 from solutions containing 0.1-1.0 M HCl and 0.5-2.0 vol.% H 2 O 2 . The system should be suitable for fast on-line experiments if seaborgium exibits a non-uranium-like behaviour. Adding hydrogen peroxide to mixed HCl/HF solutions suppresses the partial sorption of W and, presumably seaborgium, on the cation exchanger. This way, the elution volume can be minimized. Prospects for anion exchange separations of group 6 from 4 elements are also briefly discussed. (orig.)

  13. Electrochemical improvement of low-temperature petroleum cokes by chemical oxidation with H2O2 for their use as anodes in lithium ion batteries

    International Nuclear Information System (INIS)

    Concheso, A.; Santamaria, R.; Menendez, R.; Jimenez-Mateos, J.M.; Alcantara, R.; Lavela, P.; Tirado, J.L.

    2006-01-01

    The electrochemical performance of non-graphitized petroleum cokes has been improved by mild oxidation using hydrogen peroxide, a procedure used for the first time in these materials. For this purpose, various carbonisation temperatures and H 2 O 2 treatments were tested. For low sulfur content cokes, the aqueous oxidative treatment significantly increases the capacity values above 372 mAh/g during the first cycles. In contrast, cokes with a sulfur content of ca. 5%, did not shown a real improvement. The former results have been interpreted in terms of an effective oxidation of the particles surface, which removes unorganized carbon, where lithium can be irreversibly trapped. Moreover, a stable and less resistive passivating layer grows during the first discharge of lithium, as revealed by impedance spectroscopy. Therefore, chemical procedures, as mild oxidation, open an interesting field of research for the improvement of disordered carbons as anode materials in lithium ion batteries

  14. Decolorization of Mordant red 73 azo dye in water using H2O2/UV and photo-Fenton treatment.

    Science.gov (United States)

    Elmorsi, Taha M; Riyad, Yasser M; Mohamed, Zeinhom H; Abd El Bary, Hassan M H

    2010-02-15

    Decolorization of the Mordant red 73 (MR73) azo dye in water was investigated in laboratory-scale experiments using UV/H(2)O(2) and photo-Fenton treatments. Photodegradation experiments were carried out in a stirred batch photoreactor equipped with a low-pressure mercury lamp as UV source at 254 nm. The effect of operating parameters such as pH, [H(2)O(2)](,) [dye] and the presence of inorganic salts (NaNO(3), NaCl and Na(2)CO(3)) were also investigated. The results indicated that complete dye decolorization was obtained in less than 60 min under optimum conditions. Furthermore, results showed that dye degradation was dependent upon pH, [H(2)O(2)] and initial dye concentration. The presence of chloride ion led to large decreases in the photodegradation rate of MR73 while both nitrate and carbonate ions have a slight effect. The photo-Fenton treatment, in the presence of Fe powder as a source of Fe(2+) ions, was highly efficient and resulted in 99% decolorization of the dye in 15 min. Mineralization of MR73 dye was investigated by determining chemical oxygen demand (COD). In a 3h photoperiod "65%" of the dye was mineralized by the H(2)O(2)/UV process, while the photo-Fenton treatment was more efficient producing 85% mineralization over the same 3-h period.

  15. Energy Effectiveness of Direct UV and UV/H2O2 Treatment of Estrogenic Chemicals in Biologically Treated Sewage

    Directory of Open Access Journals (Sweden)

    Kamilla M. S. Hansen

    2012-01-01

    Full Text Available Continuous exposure of aquatic life to estrogenic chemicals via wastewater treatment plant effluents has in recent years received considerable attention due to the high sensitivity of oviparous animals to disturbances of estrogen-controlled physiology. The removal efficiency by direct UV and the UV/H2O2 treatment was investigated in biologically treated sewage for most of the estrogenic compounds reported in wastewater. The investigated compounds included parabens, industrial phenols, sunscreen chemicals, and steroid estrogens. Treatment experiments were performed in a flow through setup. The effect of different concentrations of H2O2 and different UV doses was investigated for all compounds in an effluent from a biological wastewater treatment plant. Removal effectiveness increased with H2O2 concentration until 60 mg/L. The treatment effectiveness was reported as the electrical energy consumed per unit volume of water treated required for 90% removal of the investigated compound. It was found that the removal of all the compounds was dependent on the UV dose for both treatment methods. The required energy for 90% removal of the compounds was between 28 kWh/m3 (butylparaben and 1.2 kWh/m3 (estrone for the UV treatment. In comparison, the UV/H2O2 treatment required between 8.7 kWh/m3 for bisphenol A and benzophenone-7 and 1.8 kWh/m3 for ethinylestradiol.

  16. Direct comparison of gluco-oligosaccharide oxidase variants and glucose oxidase: substrate range and H2O2 stability.

    Science.gov (United States)

    Vuong, Thu V; Foumani, Maryam; MacCormick, Benjamin; Kwan, Rachel; Master, Emma R

    2016-11-21

    Glucose oxidase (GO) activity is generally restricted to glucose and is susceptible to inactivation by H 2 O 2 . By comparison, the Y300A variant of gluco-oligosaccharide oxidase (GOOX) from Sarocladium strictum showed broader substrate range and higher H 2 O 2 stability. Specifically, Y300A exhibited up to 40 times higher activity on all tested sugars except glucose, compared to GO. Moreover, fusion of the Y300A variant to a family 22 carbohydrate binding module from Clostridium thermocellum (CtCBM22A) nearly doubled its catalytic efficiency on glucose, while retaining significant activity on oligosaccharides. In the presence of 200 mM of H 2 O 2 , the recombinant CtCBM22A_Y300A retained 80% of activity on glucose and 100% of activity on cellobiose, the preferred substrate for this enzyme. By contrast, a commercial glucose oxidase reported to contain ≤0.1 units catalase/ mg protein, retained 60% activity on glucose under the same conditions. GOOX variants appear to undergo a different mechanism of inactivation, as a loss of histidine instead of methionine was observed after H 2 O 2 incubation. The addition of CtCBM22A also promoted functional binding of the fusion enzyme to xylan, facilitating its simultaneous purification and immobilization using edible oat spelt xylan, which might benefit the usage of this enzyme preparation in food and baking applications.

  17. Degradation of Pentachlorophenol in Aqueous Solution by the UV/ZrO 2 /H 2 O 2 Photocatalytic Process

    Directory of Open Access Journals (Sweden)

    Mohammad Reza Samarghandi

    2015-12-01

    Full Text Available Pentachlorophenol (PCP, which is one of the resistant phenolic compounds, has been classified in the category of EPA’s priority pollutants due to its high toxicity and carcinogenic potential. Therefore, its removal from water and wastewater is very important. Various methods have been studied for removing the compound, among which advanced oxidation processes (AOPs have attracted much attention because of ease of application and high efficiency. Thus the aim of this study was to investigate the efficiency of the UV/ZrO2/H2O2 process, as an AOP, for PCP removal from aquatic environments. The effects of several parameters such as ultraviolet (UV exposure time, initial PCP concentration, pH, concentration of zirconium dioxide (ZrO2 nanoparticles, and H2O2 concentration were studied. Kinetics of the reaction was also detected. The concentration of the stated materials in the samples was determined using a spectrophotometer at 500 nm. The results showed that the highest efficiency (approximately 100% was reached at optimized conditions of pH 6, contact time of 30 minutes, initial PCP concentration of 20 mg/L, the nanoparticles concentration of 0.1 g/L and H2O2 concentration of 14.7 mM/L. Also, the process followed the first order kinetics reaction. The obtained results illustrated that the UV/ZrO2/H2O2 process has a high ability in removing PCP.

  18. Real-Time in Vivo Detection of H2O2 Using Hyperpolarized 13C-Thiourea.

    Science.gov (United States)

    Wibowo, Arif; Park, Jae Mo; Liu, Shie-Chau; Khosla, Chaitan; Spielman, Daniel M

    2017-07-21

    Reactive oxygen species (ROS) are essential cellular metabolites widely implicated in many diseases including cancer, inflammation, and cardiovascular and neurodegenerative disorders. Yet, ROS signaling remains poorly understood, and their measurements are a challenge due to high reactivity and instability. Here, we report the development of 13 C-thiourea as a probe to detect and measure H 2 O 2 dynamics with high sensitivity and spatiotemporal resolution using hyperpolarized 13 C magnetic resonance spectroscopic imaging. In particular, we show 13 C-thiourea to be highly polarizable and to possess a long spin-lattice relaxation time (T 1 ), which enables real-time monitoring of ROS-mediated transformation. We also demonstrate that 13 C-thiourea reacts readily with H 2 O 2 to give chemically distinguishable products in vitro and validate their detection in vivo in a mouse liver. This study suggests that 13 C-thiourea is a promising agent for noninvasive detection of H 2 O 2 in vivo. More broadly, our findings outline a viable clinical application for H 2 O 2 detection in patients with a range of diseases.

  19. Drought controls on H2O2 accumulation, catalase (CAT) activity and CAT gene expression in wheat.

    Science.gov (United States)

    Luna, Celina M; Pastori, Gabriela M; Driscoll, Simon; Groten, Karin; Bernard, Stephanie; Foyer, Christine H

    2005-01-01

    Plants co-ordinate information derived from many diverse external and internal signals to ensure appropriate control of gene expression under optimal and stress conditions. In this work, the relationships between catalase (CAT) and H2O2 during drought in wheat (Triticum aestivum L.) are studied. Drought-induced H2O2 accumulation correlated with decreases in soil water content and CO2 assimilation. Leaf H2O2 content increased even though total CAT activity doubled under severe drought conditions. Diurnal regulation of CAT1 and CAT2 mRNA abundance was apparent in all conditions and day/night CAT1 and CAT2 expression patterns were modified by mild and severe drought. The abundance of CAT1 transcripts was regulated by circadian controls that persisted in continuous darkness, while CAT2 was modulated by light. Drought decreased abundance, and modified the pattern, of CAT1 and CAT2 mRNAs. It was concluded that the complex regulation of CAT mRNA, particularly at the level of translation, allows precise control of leaf H2O2 accumulation.

  20. Protective effects of veskamide, enferamide, becatamide, and oretamide on H2O2-induced apoptosis of PC-12 cells

    Science.gov (United States)

    Veskamide, enferamide, becatamide, and oretamide are phenolic amides whose analogues are found in plants. In this study, the four amides were prepared by chemical synthesis and their protective effects on H(2)O(2)-induced apoptosis in PC-12 cells were investigated. The syntheses were relatively si...

  1. Atomic scale simulation of H2O2 permeation through aquaporin: toward the understanding of plasma cancer treatment

    Science.gov (United States)

    Yusupov, Maksudbek; Yan, Dayun; Cordeiro, Rodrigo M.; Bogaerts, Annemie

    2018-03-01

    Experiments have demonstrated the potential selective anticancer capacity of cold atmospheric plasmas (CAPs), but the underlying mechanisms remain unclear. Using computer simulations, we try to shed light on the mechanism of selectivity, based on aquaporins (AQPs), i.e. transmembrane protein channels transferring external H2O2 and other reactive oxygen species, created e.g. by CAPs, to the cell interior. Specifically, we perform molecular dynamics simulations for the permeation of H2O2 through AQP1 (one of the members of the AQP family) and the palmitoyl-oleoyl-phosphatidylcholine (POPC) phospholipid bilayer (PLB). The free energy barrier of H2O2 across AQP1 is lower than for the POPC PLB, while the permeability coefficient, calculated using the free energy and diffusion rate profiles, is two orders of magnitude higher. This indicates that the delivery of H2O2 into the cell interior should be through AQP. Our study gives a better insight into the role of AQPs in the selectivity of CAPs for treating cancer cells.

  2. Degradation Mechanism of Cyanobacterial Toxin Cylindrospermopsin by Hydroxyl Radicals in Homogeneous UV/H2O2 Process

    Science.gov (United States)

    The degradation of cylindrospermopsin (CYN), a widely distributed and highly toxic cyanobacterial toxin (cyanotoxin), remains poorly elucidated. In this study, the mechanism of CYN destruction by UV-254 nm/H2O2 advanced oxidation process (AOP) was investigated by mass spectrometr...

  3. A novel H(2)O(2) amperometric biosensor based on gold nanoparticles/self-doped polyaniline nanofibers.

    Science.gov (United States)

    Chen, Xiaojun; Chen, Zixuan; Zhu, Jinwei; Xu, Chenbin; Yan, Wei; Yao, Cheng

    2011-10-01

    A new kind of gold nanoparticles/self-doped polyaniline nanofibers (Au/SPAN) with grooves has been prepared for the immobilization of horseradish peroxidase (HRP) on the surface of glassy carbon electrode (GCE). The ratio of gold in the composite nanofibers was up to 64%, which could promote the conductivity and biocompatibility of SPAN and increase the immobilized amount of HRP molecules greatly. The electrode exhibits enhanced electrocatalytic activity in the reduction of H(2)O(2) in the presence of the mediator hydroquinone (HQ). The effects of concentration of HQ, solution pH and the working potential on the current response of the modified electrode toward H(2)O(2) were optimized to obtain the maximal sensitivity. The proposed biosensor exhibited a good linear response in the range from 10 to 2000 μM with a detection limit of 1.6 μM (S/N=3) under the optimum conditions. The response showed Michaelis-Menten behavior at larger H(2)O(2) concentrations, and the apparent Michaelis-Menten constant K(m) was estimated to be 2.21 mM. The detection of H(2)O(2) concentration in real sample showed acceptable accuracy with the traditional potassium permanganate titration. Copyright © 2011 Elsevier B.V. All rights reserved.

  4. Sequencing treatment of industrial wastewater with ultraviolet/H2O2 advanced oxidation and moving bed bioreactor

    Directory of Open Access Journals (Sweden)

    Mohammad Mehdi Mehrabani Ardekani

    2015-01-01

    Full Text Available Aims: The main purpose of this study was to determine the efficiency of a sequencing treatment including ultraviolet (UV/H 2 O 2 oxidation followed by a moving bed bioreactor (MBBR. Materials and Methods: Effect of solution pH, reaction time, and H 2 O 2 concentration were investigated for an industrial wastewater sample. The effluent of the advanced oxidation processes unit was introduced to the MBBR operated for three hydraulic retention times of 4, 8, and 12 h. Results: The optimum condition for industrial wastewater treatment via advanced oxidation was solution pH: 7, H 2 O 2 dose: 1000 mg/L and 90 min reaction time. These conditions led to 74.68% chemical oxygen demand (COD removal and 66.15% biochemical oxygen demand (BOD 5 removal from presedimentation step effluent that initially had COD and BOD 5 contents of 4,400 and 1,950 mg/L, respectively. Conclusion: Combination of UV/H 2 O 2 advanced oxidation with MBBR could result in effluents that meet water quality standards for discharge to receiving waters.

  5. CodY Regulates Thiol Peroxidase Expression as Part of the Pneumococcal Defense Mechanism against H2O2 Stress

    NARCIS (Netherlands)

    Hajaj, Barak; Yesilkaya, Hasan; Shafeeq, Sulman; Zhi, Xiangyun; Benisty, Rachel; Tchalah, Shiran; Kuipers, Oscar P; Porat, Nurith

    2017-01-01

    Streptococcus pneumoniae is a facultative anaerobic pathogen. Although it maintains fermentative metabolism, during aerobic growth pneumococci produce high levels of H2O2, which can have adverse effects on cell viability and DNA, and influence pneumococcal interaction with its host. The pneumococcus

  6. Adsorbed Layers of D2, H2, O2, and 3He on Graphite Studied by Neutron Scattering

    DEFF Research Database (Denmark)

    Nielsen, Mourits; McTague, J. P.; Ellenson, W. D.

    1977-01-01

    The phase diagrams of adsorbed monolayers of D2, H2, O2, and 3He on graphite have been measured by neutron diffraction. H2 and D2-layers have a registered √3 structure at low coverages, and at monolayer completion they have a dense triangular structure, which is incommensurate with the substrate...

  7. Development of an online analyzer of atmospheric H 2O 2 and several organic hydroperoxides for field campaigns

    Science.gov (United States)

    François, S.; Sowka, I.; Monod, A.; Temime-Roussel, B.; Laugier, J. M.; Wortham, H.

    2005-03-01

    An online automated instrument was developed for atmospheric measurements of hydroperoxides with separation and quantification of H 2O 2 and several organic hydroperoxides. Samples were trapped in aqueous solutions in a scrubbing glass coil. Analyses were performed on an HPLC column followed by para-hydroxyphenylacetic acid (POPHA) acetic acid and peroxidase derivatization and fluorescence detection. Analytical and sampling tests were performed on different parameters to obtain optimum signal-to-noise ratios, high resolution and collection efficiencies higher than 95% for H 2O 2 and organic hydroperoxides. The obtained performances show large improvements compared to previous studies. The sampling and analytical devices can be coupled providing an online analyzer. The device was used during two field campaigns in the Marseilles area in June 2001 (offline analyzer) and in July 2002 (online analyzer) at rural sites at low and high altitudes, respectively, during the ESCOMPTE and BOND campaigns. During the ESCOMPTE campaign, H 2O 2 was detected occasionally, and no organic hydroperoxides was observed. During the BOND campaign, substantial amounts of H 2O 2 and 1-HEHP+MHP were often detected, and two other organic hydroperoxides were occasionally detected. These observations are discussed.

  8. Energy Effectiveness of Direct UV and UV/H2O2 Treatment of Estrogenic Chemicals in Biologically Treated Sewage

    DEFF Research Database (Denmark)

    Hansen, Kamilla Marie Speht; Andersen, Henrik Rasmus

    2012-01-01

    and the UV/H2O2-treatment were investigated in biologically treated sewage for most of the estrogenic compounds reported in wastewater. The investigated compounds included parabens, industrial phenols, sunscreen chemicals and steroid estrogens. Treatment experiments were performed in a flow through set...

  9. Rice Bioactive Peptide Binding with TLR4 To Overcome H2O2-Induced Injury in Human Umbilical Vein Endothelial Cells through NF-κB Signaling.

    Science.gov (United States)

    Liang, Ying; Lin, Qinlu; Huang, Ping; Wang, Yuqian; Li, Jiajia; Zhang, Lin; Cao, Jianzhong

    2018-01-17

    Reactive oxygen species-induced vessel endothelium injury is crucial in cardiovascular diseases progression. Rice-derived bran bioactive peptides (RBAP) might exert antioxidant effect through unknown mechanisms. Herein, we validated the antioxidant effect and mechanism of RBAP on H 2 O 2 -induced oxidative injury in human umbilical vein endothelial cells (HUVECs). Here, HUVECs were treated with RBAP under H 2 O 2 stimulation; the effects of RBAP on HUVECs oxidative injury were evaluated. H 2 O 2 injury-induced cell morphology changes were ameliorated by RBAP. The effect of H 2 O 2 - on HUVEC apoptosis (percentage of apoptotic cell: 38.00 ± 2.00 in H 2 O 2 group vs 21.07 ± 2.06 in RBAP + H 2 O 2 group, P = 0.0013 compared to H 2 O 2 group), the protein levels of cleaved caspase-3 (relative protein expression: 2.90 ± 0.10 in H 2 O 2 group vs 1.82 ± 0.09 in RBAP + H 2 O 2 group, P < 0.0001 compared to H 2 O 2 group) and p-p65 (relative protein expression: 1.86 ± 0.09 in H 2 O 2 group vs 1.35 ± 0.08 in RBAP + H 2 O 2 group, P < 0.0001 compared to H 2 O 2 group) could be attenuated by RBAP. RBAP exerts its protective function through binding with Toll-like receptor 4 (TLR4). Taken together, RBAP protects HUVECs against H 2 O 2 -induced oxidant injury, which provided the theoretical basis for the molecular mechanism of rice deep processing and exploitation of functional peptides.

  10. Study on Enhancement Principle and Stabilization for the Luminol-H2O2-HRP Chemiluminescence System.

    Directory of Open Access Journals (Sweden)

    Lihua Yang

    Full Text Available A luminol-H2O2-HRP chemiluminescence system with high relative luminescent intensity (RLU and long stabilization time was investigated. First, the comparative study on the enhancement effect of ten compounds as enhancers to the luminol-H2O2-HRP chemiluminescence system was carried out, and the results showed that 4-(imidazol-1-ylphenol (4-IMP, 4-iodophenol (4-IOP, 4-bromophenol (4-BOP and 4-hydroxy-4'-iodobiphenyl (HIOP had the best performance. Based on the experiment, the four enhancers were dissolved in acetone, acetonitrile, methanol, and dimethylformamide (DMF with various concentrations, the results indicated that 4-IMP, 4-IOP, 4-BOP and HIOP dissolved in DMF with the concentrations of 0.2%, 3.2%, 1.6% and 3.2% could get the highest RLU values. Subsequently, the influences of pH, ionic strength, HRP, 4-IMP, 4-IOP, 4-BOP, HIOP, H2O2 and luminol on the stabilization of the luminol-H2O2-HRP chemiluminescence system were studied, and we found that pH value, ionic strength, 4-IMP, 4-IOP, 4-BOP, HIOP, H2O2 and luminol have little influence on luminescent stabilization, while HRP has a great influence. In different ranges of HRP concentration, different enhancers should be selected. When the concentration is within the range of 0~6 ng/mL, 4-IMP should be selected. When the concentration of HRP ranges from 6 to 25 ng/mL, 4-IOP was the best choice. And when the concentration is within the range of 25~80 ng/mL, HIOP should be selected as the enhancer. Finally, the three well-performing chemiluminescent enhanced solutions (CESs have been further optimized according to the three enhancers (4-IMP, 4-IOP and HIOP in their utilized HRP concentration ranges.

  11. Comparative investigation of X-ray contrast medium degradation by UV/chlorine and UV/H2O2.

    Science.gov (United States)

    Kong, Xiujuan; Jiang, Jin; Ma, Jun; Yang, Yi; Pang, Suyan

    2018-02-01

    The degradation of iopamidol and diatrizoate sodium (DTZ) by UV/chlorine was carried out according to efficiency, mechanism, and oxidation products, and compared to that by UV/H 2 O 2 . The pseudo-first order rate (k') of iopamidol and DTZ was accelerated by UV/chlorine compared to that by UV and chlorine alone. k' of iopamidol and DTZ by UV/chlorine increased with increasing chlorine dosage. Both of iopamidol and DTZ could not be effectively removed by UV/H 2 O 2 compared to that by UV/chlorine. Secondary radicals (Cl 2 - and ClO) rather than primary radicals (HO and Cl) were demonstrated to be mainly responsible for the enhanced removal of iopamidol and DTZ by UV/chlorine. The oxidation products of iopamidol and DTZ resulting from UV/chlorine and UV/H 2 O 2 process were identified, and differences existed in the two systems. IO 3 - (the desired sink of I - ) was the major inorganic product in the UV/chlorine process whereas I - was the predominant inorganic product in the UV/H 2 O 2 process. The formation of chlorine-containing products during the degradation of iopamidol and DTZ by UV/chlorine was also observed. H-abstraction, additions, de-iodination were shared during the degradation of iopamidol by UV/chlorine and UV/H 2 O 2 . Neutral pH condition was preferred for the removal of iopamidol and DTZ by UV/chlorine. UV/chlorine could also be applied in real waters for the removal of iopamidol and DTZ. Copyright © 2017 Elsevier Ltd. All rights reserved.

  12. Advanced oxidation removal of hypophosphite by O3/H2O2 combined with sequential Fe(II) catalytic process.

    Science.gov (United States)

    Zhao, Zilong; Dong, Wenyi; Wang, Hongjie; Chen, Guanhan; Wang, Wei; Liu, Zekun; Gao, Yaguang; Zhou, Beili

    2017-08-01

    Elimination of hypophosphite (HP) was studied as an example of nickel plating effluents treatment by O 3 /H 2 O 2 and sequential Fe(II) catalytic oxidation process. Performance assessment performed with artificial HP solution by varying initial pH and employing various oxidation processes clearly showed that the O 3 /H 2 O 2 ─Fe(II) two-step oxidation process possessed the highest removal efficiency when operating under the same conditions. The effects of O 3 dosing, H 2 O 2 concentration, Fe(II) addition and Fe(II) feeding time on the removal efficiency of HP were further evaluated in terms of apparent kinetic rate constant. Under improved conditions (initial HP concentration of 50 mg L -1 , 75 mg L -1 O 3 , 1 mL L -1 H 2 O 2 , 150 mg L -1 Fe(II) and pH 7.0), standard discharge (<0.5 mg L -1 in China) could be achieved, and the Fe(II) feeding time was found to be the limiting factor for the evolution of apparent kinetic rate constant in the second stage. Characterization studies showed that neutralization process after oxidation treatment favored the improvement of phosphorus removal due to the formation of more metal hydroxides. Moreover, as a comparison with lab-scale Fenton approach, the O 3 /H 2 O 2 ─Fe(II) oxidation process had more competitive advantages with respect to applicable pH range, removal efficiency, sludge production as well as economic costs. Copyright © 2017 Elsevier Ltd. All rights reserved.

  13. Degradation mechanism of alachlor during direct ozonation and O(3)/H(2)O(2) advanced oxidation process.

    Science.gov (United States)

    Qiang, Zhimin; Liu, Chao; Dong, Bingzhi; Zhang, Yalei

    2010-01-01

    The degradation of alachlor by direct ozonation and advanced oxidation process O(3)/H(2)O(2) was investigated in this study with focus on identification of degradation byproducts. The second-order reaction rate constant between ozone and alachlor was determined to be 2.5+/-0.1M(-1)s(-1) at pH 7.0 and 20 degrees C. Twelve and eight high-molecular-weight byproducts (with the benzene ring intact) from alachlor degradation were identified during direct ozonation and O(3)/H(2)O(2), respectively. The common degradation byproducts included N-(2,6-diethylphenyl)-methyleneamine, 8-ethyl-3,4-dihydro-quinoline, 8-ethyl-quinoline, 1-chloroacetyl-2-hydro-3-ketone-7-acetyl-indole, 2-chloro-2',6'-diacetyl-N-(methoxymethyl)acetanilide, 2-chloro-2'-acetyl-6'-ethyl-N-(methoxymethyl)-acetanilide, and two hydroxylated alachlor isomers. In direct ozonation, four more byproducts were also identified including 1-chloroacetyl-2,3-dihydro-7-ethyl-indole, 2-chloro-2',6'-ethyl-acetanilide, 2-chloro-2',6'-acetyl-acetanilide and 2-chloro-2'-ethyl-6'-acetyl-N-(methoxymethyl)-acetanilide. Degradation of alachlor by O(3) and O(3)/H(2)O(2) also led to the formation of low-molecular-weight byproducts including formic, acetic, propionic, monochloroacetic and oxalic acids as well as chloride ion (only detected in O(3)/H(2)O(2)). Nitrite and nitrate formation was negligible. Alachlor degradation occurred via oxidation of the arylethyl group, N-dealkylation, cyclization and cleavage of benzene ring. After O(3) or O(3)/H(2)O(2) treatment, the toxicity of alachlor solution examined by the Daphnia magna bioassay was slightly