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Sample records for activity hydrogen peroxide

  1. Antibacterial activity of hydrogen peroxide and the lactoperoxidase-hydrogen peroxide-thiocyanate system against oral streptococci.

    OpenAIRE

    Thomas, E L; Milligan, T W; Joyner, R E; Jefferson, M M

    1994-01-01

    In secreted fluids, the enzyme lactoperoxidase (LP) catalyzes the oxidation of thiocyanate ion (SCN-) by hydrogen peroxide (H2O2), producing the weak oxidizing agent hypothiocyanite (OSCN-), which has bacteriostatic activity. However, H2O2 has antibacterial activity in the absence of LP and thiocyanate (SCN-). Therefore, LP may increase antibacterial activity by using H2O2 to produce a more effective inhibitor of bacterial metabolism and growth, or LP may protect bacteria against the toxicity...

  2. Overoxidation of chloroplast 2-Cys peroxiredoxins: balancing toxic and signaling activities of hydrogen peroxide

    OpenAIRE

    Puerto-Galán, Leonor; Pérez-Ruiz, Juan M.; Ferrández, Julia; Cano, Beatriz; Naranjo, Belén; Nájera, Victoria A.; González, Maricruz; Lindahl, Anna M.; Cejudo, Francisco J.

    2013-01-01

    Photosynthesis, the primary source of biomass and oxygen into the biosphere, involves the transport of electrons in the presence of oxygen and, therefore, chloroplasts constitute an important source of reactive oxygen species, including hydrogen peroxide. If accumulated at high level, hydrogen peroxide may exert a toxic effect; however, it is as well an important second messenger. In order to balance the toxic and signaling activities of hydrogen peroxide its level has to be tightly controlle...

  3. Overoxidation of chloroplast 2-Cys peroxiredoxins: balancing toxic and signaling activities of hydrogen peroxide

    OpenAIRE

    Leonor ePuerto-Galán; Juan Manuel Pérez-Ruiz; Julia eFerrández; Beatriz eCano; Belén eNaranjo; Victoria Armario Nájera; Maricruz eGonzález; Anna Marika eLindahl; Francisco Javier Cejudo

    2013-01-01

    Photosynthesis, the primary source of biomass and oxygen into the biosphere, involves the transport of electrons in the presence of oxygen and, therefore, chloroplasts constitute an important source of reactive oxygen species (ROS), including hydrogen peroxide. If accumulated at high level, hydrogen peroxide may exert a toxic effect; however, it is as well an important second messenger. In order to balance the toxic and signaling activities of hydrogen peroxide its level has to be tightly con...

  4. Electrochemical Hydrogen Peroxide Generator

    Science.gov (United States)

    Tennakoon, Charles L. K.; Singh, Waheguru; Anderson, Kelvin C.

    2010-01-01

    needed are water and oxygen or air. 2. The product is pure and can therefore be used in disinfection applications directly or after proper dilution with water. 3. Oxygen generated in the anode compartment is used in the electrochemical reduction process; in addition, external oxygen is used to establish a high flow rate in the cathode compartment to remove the desired product efficiently. Exiting oxygen can be recycled after separation of liquid hydrogen peroxide product, if so desired. 4. The process can be designed for peroxide generation under microgravity conditions. 5. High concentrations of the order of 6-7 wt% can be generated by this method. This method at the time of this reporting is superior to what other researchers have reported. 6. The cell design allows for stacking of cells to increase the hydrogen peroxide production. 7. The catalyst mix containing a diquaternary ammonium compound enabled not only higher concentration of hydrogen peroxide but also higher current efficiency, improved energy efficiency, and catalyst stability. 8. The activity of the catalyst is maintained even after repeated periods of system shutdown. 9. The catalyst system can be extended for fuel-cell cathodes with suitable modifications.

  5. Overoxidation of chloroplast 2-Cys peroxiredoxins: balancing toxic and signaling activities of hydrogen peroxide

    Directory of Open Access Journals (Sweden)

    Leonor ePuerto-Galán

    2013-08-01

    Full Text Available Photosynthesis, the primary source of biomass and oxygen into the biosphere, involves the transport of electrons in the presence of oxygen and, therefore, chloroplasts constitute an important source of reactive oxygen species (ROS, including hydrogen peroxide. If accumulated at high level, hydrogen peroxide may exert a toxic effect; however, it is as well an important second messenger. In order to balance the toxic and signaling activities of hydrogen peroxide its level has to be tightly controlled. To this end, chloroplasts are equipped with different antioxidant systems such as 2-Cys peroxiredoxins (2-Cys Prxs, thiol-based peroxidases able to reduce hydrogen- and organic peroxides. At high peroxide concentrations the peroxidase function of 2-Cys Prxs may become inactivated through a process of overoxidation. This inactivation has been proposed to explain the signaling function of hydrogen peroxide in eukaryotes, whereas in prokaryotes, the 2-Cys Prxs of which were considered to be insensitive to overoxidation, the signaling activity of hydrogen peroxide is less relevant. Here we discuss the current knowledge about the mechanisms controlling 2-Cys Prx overoxidation in chloroplasts, organelles with an important signaling function in plants. Given the prokaryotic origin of chloroplasts, we discuss the occurrence of 2-Cys Prx overoxidation in cyanobacteria with the aim of identifying similarities between chloroplasts and their ancestors regarding their response to hydrogen peroxide.

  6. Overoxidation of chloroplast 2-Cys peroxiredoxins: balancing toxic and signaling activities of hydrogen peroxide.

    Science.gov (United States)

    Puerto-Galán, Leonor; Pérez-Ruiz, Juan M; Ferrández, Julia; Cano, Beatriz; Naranjo, Belén; Nájera, Victoria A; González, Maricruz; Lindahl, Anna M; Cejudo, Francisco J

    2013-01-01

    Photosynthesis, the primary source of biomass and oxygen into the biosphere, involves the transport of electrons in the presence of oxygen and, therefore, chloroplasts constitute an important source of reactive oxygen species, including hydrogen peroxide. If accumulated at high level, hydrogen peroxide may exert a toxic effect; however, it is as well an important second messenger. In order to balance the toxic and signaling activities of hydrogen peroxide its level has to be tightly controlled. To this end, chloroplasts are equipped with different antioxidant systems such as 2-Cys peroxiredoxins (2-Cys Prxs), thiol-based peroxidases able to reduce hydrogen and organic peroxides. At high peroxide concentrations the peroxidase function of 2-Cys Prxs may become inactivated through a process of overoxidation. This inactivation has been proposed to explain the signaling function of hydrogen peroxide in eukaryotes, whereas in prokaryotes, the 2-Cys Prxs of which were considered to be insensitive to overoxidation, the signaling activity of hydrogen peroxide is less relevant. Here we discuss the current knowledge about the mechanisms controlling 2-Cys Prx overoxidation in chloroplasts, organelles with an important signaling function in plants. Given the prokaryotic origin of chloroplasts, we discuss the occurrence of 2-Cys Prx overoxidation in cyanobacteria with the aim of identifying similarities between chloroplasts and their ancestors regarding their response to hydrogen peroxide.

  7. Isolation of lactic acid bacteria exhibiting high scavenging activity for environmental hydrogen peroxide from fermented foods and its two scavenging enzymes for hydrogen peroxide.

    Science.gov (United States)

    Watanabe, Akio; Kaneko, Chiaki; Hamada, Yasuhiro; Takeda, Kouji; Kimata, Shinya; Matsumoto, Takashi; Abe, Akira; Tanaka, Naoto; Okada, Sanae; Uchino, Masataka; Satoh, Junichi; Nakagawa, Junichi; Niimura, Youichi

    2016-01-01

    To obtain lactic acid bacteria that scavenge environmental hydrogen peroxide, we developed a specialized enrichment medium and successfully isolated Pediococcus pentosaceus Be1 strain from a fermented food. This strain showed vigorous environmental hydrogen peroxide scavenging activity over a wide range of hydrogen peroxide concentrations. High Mn-catalase and NADH peroxidase activities were found in the cell-free extract of the P. pentosaceus Be1 strain, and these two hydrogen peroxide scavenging enzymes were purified from the cell-free extract of the strain. Mn-catalase has been purified from several microorganisms by several researchers, and the NADH peroxidase was first purified from the original strain in this report. After cloning the genes of the Mn-catalase and the NADH peroxidase, the deduced amino acid sequences were compared with those of known related enzymes. PMID:27118075

  8. Re-Examining the Role of Hydrogen Peroxide in Bacteriostatic and Bactericidal Activities of Honey

    OpenAIRE

    Brudzynski, Katrina; Abubaker, Kamal; St-Martin, Laurent; Castle, Alan

    2011-01-01

    The aim of this study was to critically analyze the effects of hydrogen peroxide on growth and survival of bacterial cells in order to prove or disprove its purported role as a main component responsible for the antibacterial activity of honey. Using the sensitive peroxide/peroxidase assay, broth microdilution assay and DNA degradation assays, the quantitative relationships between the content of H2O2 and honey’s antibacterial activity was established. The results showed that: (A) the average...

  9. Efficient Method for the Determination of the Activation Energy of the Iodide-Catalyzed Decomposition of Hydrogen Peroxide

    Science.gov (United States)

    Sweeney, William; Lee, James; Abid, Nauman; DeMeo, Stephen

    2014-01-01

    An experiment is described that determines the activation energy (E[subscript a]) of the iodide-catalyzed decomposition reaction of hydrogen peroxide in a much more efficient manner than previously reported in the literature. Hydrogen peroxide, spontaneously or with a catalyst, decomposes to oxygen and water. Because the decomposition reaction is…

  10. Hydrogen peroxide activates activator protein-1 and mitogen-activated protein kinases in pancreatic stellate cells.

    Science.gov (United States)

    Kikuta, Kazuhiro; Masamune, Atsushi; Satoh, Masahiro; Suzuki, Noriaki; Satoh, Kennichi; Shimosegawa, Tooru

    2006-10-01

    Activated pancreatic stellate cells (PSCs) are implicated in the pathogenesis of pancreatic inflammation and fibrosis, where oxidative stress is thought to play a key role. Reactive oxygen species such as hydrogen peroxide (H(2)O(2)) may act as a second messenger to mediate the actions of growth factors and cytokines. But the role of reactive oxygen species in the activation and regulation of cell functions in PSCs remains largely unknown. We here examined the effects of H(2)O(2) on the activation of signal transduction pathways and cell functions in PSCs. PSCs were isolated from the pancreas of male Wistar rats, and used in their culture-activated, myofibroblast-like phenotype unless otherwise stated. Activation of transcription factors was examined by electrophoretic mobility shift assay and luciferase assay. Activation of mitogen-activated protein (MAP) kinases was assessed by Western blotting using anti-phosphospecific antibodies. The effects of H(2)O(2) on proliferation, alpha(1)(I)procollagen gene expression, and monocyte chemoattractant protein-1 production were evaluated. The effect of H(2)O(2) on the transformation of freshly isolated PSCs in culture was also assessed. H(2)O(2) at non-cytotoxic concentrations (up to 100 microM) induced oxidative stress in PSCs. H(2)O(2) activated activator protein-1, but not nuclear factor kappaB. In addition, H(2)O(2) activated three classes of MAP kinases: extracellular signal-regulated kinase, c-Jun N-terminal kinase, and p38 MAP kinase. H(2)O(2) induced alpha(1)(I)procollagen gene expression but did not induce proliferation or monocyte chemoattractant protein-1 production. H(2)O(2) did not initiate the transformation of freshly isolated PSCs to myofibroblast-like phenotype. Specific activation of these signal transduction pathways and collagen gene expression by H(2)O(2) may play a role in the pathogenesis of pancreatic fibrosis.

  11. Antitumor effect of synergistic contribution of nitrite and hydrogen peroxide in the plasma activated medium

    Science.gov (United States)

    Kurake, Naoyuki; Tanaka, Hiromasa; Ishikawa, Kenji; Nakamura, Kae; Kajiyama, Hiroaki; Kikkawa, Fumiaki; Kondo, Takashi; Mizuno, Masaaki; Takeda, Keigo; Kondo, Hiroki; Sekine, Makoto; Hori, Masaru

    2015-09-01

    Non-equilibrium atmospheric pressure plasmas (NEAPP) have been attracted attention in the noble application of cancer therapy. Although good effects of the Plasma-Activated-Medium (PAM) such as the selective antitumor effect and killing effect for the anticancer agent resistant cells were reported, a mechanism of this effect has not been still clarified yet. In this study, we have investigated a contribution of the reactive nitrogen and oxygen species (RNOS) generated in PAM such as hydrogen peroxide and nitrite. Those species generated in the PAM quantitatively measured by light absorbance of commercial regent. Moreover, viable cell count after cell culture with those RNOS intentionally added medium or PAM were also measured by MTS assay. Our NEAPP source generated hydrogen peroxide and nitrite with the generation ratio of 0.35 μM/s and 9.8 μM/s. In those RNOS, hydrogen peroxide has respective antitumor effect. On the other hands, nitrite has no antitumor effect singly. But, synergistically enhance the antitumor effect of hydrogen peroxide. Moreover, this effect of those RNOS also contribute for the selectively cancer killing effect of PAM.

  12. Effect of menadione and hydrogen peroxide on catalase activity in Saccharomyces yeast strains

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    Nadejda EFREMOVA

    2013-05-01

    Full Text Available It has been studied the possibility of utilization of two important oxidant factors as regulators of catalase activity in Saccharomyces yeasts. In this paper results of the screening of some Saccharomyces yeast strains for potential producers of catalase are presented. Results of the screening for potential catalase producer have revealed that Saccharomyces cerevisiae CNMN-Y-11 strain possesses the highest catalase activity (2900 U/mg protein compared with other samples. Maximum increase of catalase activity with 50-60% compared to the reference sample was established in the case of hydrogen peroxide and menadione utilization in optimal concentrations of 15 and 10 mM. This research has been demonstrated the potential benefits of application of hydrogen peroxide and menadione as stimulatory factors of catalase activity in Saccharomyces yeasts.

  13. PROCESS OPTIMIZATION OF TETRA ACETYL ETHYLENE DIAMINE ACTIVATED HYDROGEN PEROXIDE BLEACHING OF POPULUS NIGRA CTMP

    OpenAIRE

    Qiang Zhao; Junwen Pu; Shulei Mao; Guibo Qi

    2010-01-01

    To enhance the bleaching efficiency, the activator of tetra acetyl ethylene diamine (TAED) was used in conventional H2O2 bleaching. The H2O2/TAED bleaching system can accelerate the reaction rate and shorten bleaching time at relative low temperature, which can reduce the production cost. In this research, the process with hydrogen peroxide activated by TAED bleaching of Populus nigra chemi-thermo mechanical pulp was optimized. Suitable bleaching conditions were confirmed as follows: pulp con...

  14. Antibacterial Properties and Mechanism of Activity of a Novel Silver-Stabilized Hydrogen Peroxide.

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    Nancy L Martin

    Full Text Available Huwa-San peroxide (hydrogen peroxide; HSP is a NSF Standard 60 (maximum 8 mg/L(-1 new generation peroxide stabilized with ionic silver suitable for continuous disinfection of potable water. Experiments were undertaken to examine the mechanism of HSP against planktonic and biofilm cultures of indicator bacterial strains. Contact/kill time (CT relationships that achieve effective control were explored to determine the potential utility in primary disinfection. Inhibitory assays were conducted using both nutrient rich media and a medium based on synthetic wastewater. Assays were compared for exposures to three disinfectants (HSP, laboratory grade hydrogen peroxide (HP and sodium hypochlorite at concentrations of 20 ppm (therefore at 2.5 and 5 times the NSF limit for HP and sodium hypochlorite, respectively and at pH 7.0 and 8.5 in dechlorinated tap water. HSP was found to be more or equally effective as hypochlorite or HP. Results from CT assays comparing HSP and HP at different bacterial concentrations with neutralization of residual peroxide with catalase suggested that at a high bacterial concentration HSP, but not HP, was protected from catalase degradation possibly through sequestration by bacterial cells. Consistent with this hypothesis, at a low bacterial cell density residual HSP was more effectively neutralized as less HSP was associated with bacteria and therefore accessible to catalase. Silver in HSP may facilitate this association through electrostatic interactions at the cell surface. This was supported by experiments where the addition of mono (K(+ and divalent (Ca(+2 cations (0.005-0.05M reduced the killing efficacy of HSP but not HP. Experiments designed to distinguish any inhibitory effect of silver from that of peroxide in HSP were carried out by monitoring the metabolic activity of established P. aeruginosa PAO1 biofilms. Concentrations of 70-500 ppm HSP had a pronounced effect on metabolic activity while the equivalent

  15. COMPARATIVE STUDY OF ANTIBACTERIAL ACTIVITY OF PEROXYDISUCCINIC ACID, HYDROGEN PEROXIDE AND THEIR MIXTURE

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    Blazheyevskiy M.Ye.,

    2016-06-01

    Full Text Available Introduction. It is known that reactive oxygen species (ROS generated in vivo by cell aerobic metabolism cause multiple damage in different cell organelles and kill not only obligate anaerobes and microaerophilles, but also aerobes. ROS generated by phagocytes and representatives of normal microflora are an important component of macroorganism defense from most pathogens, which is explained by their ability to damage different biological structures. ROS have high reactivity and let us use them in vitro as effective biocides. Hydrogen peroxide is widely used in many industries, in particular, in medicine and veterinary as antiseptic and disinfectant agent due to its safety for environment and broad spectrum of antimicrobial activity including spore-forming bacteria. However, in the recent years certain decrease of background sensitivity of microorganisms to hydrogen peroxide and occurrence of resistant strains of pathogenic microorganisms to this agent has been noted. The aim of this work is to carry out a comparative study of antimicrobial activity of hydrogen peroxide, peroxydisuccinic acid (PDSA, monoperoxysuccinic acid (MPSA, and mixture of PDSA and hydrogen peroxide (Н2О2. Materials and methods. The substances of peroxydisuccinic acid (PDSA and monoperoxysuccinic acid (MPSA were prepared by well known methods. The following test-strains were used to assess antimicrobial activity of the agents: Staphylococcus aureus АТСС 25923, Escherichia coli АТСС 25922, Pseudomonas aeruginosa АТСС 27853, Pseudomonas aeruginosa АТСС 9027, Basillus сereus АТСС 10702, Basillus сereus АТСС 96, Basillus subtilis АТСС 6633, Proteus vulgaris ATCC 4636, Candida albicans АТСС 885/653, and Candida albicans АТСС 10231. All disinfectant agents were diluted in distilled water at 40 ºС and stirred. The microbial burden was 2∙109 CFU/ml of the medium, and for kinetic studies 105 CFU/ml of the medium, it was standardizing

  16. Activation of NF-κB and apoptosis of intestinal epithelial cells induced by hydrogen peroxide

    Institute of Scientific and Technical Information of China (English)

    李建明; 周红; 蔡黔; 肖光夏

    2002-01-01

    In vitro model of hydrogen peroxide induced apoptosis of SW-480 cells was used to investigate the role of NF-κB in the pathogenesis of reactive oxygen species induced apoptosis of intestinal epithelial cells. Methods: Ultra-structural changes were observed.Apoptosis of SW-480 cell line was determined by Annexin-V and PI double-stained flow cytometry. Nuclear translocation of NF-κB was determined by anti-NF-κB polyclonal antibody and EB double-staining. NF-κB activity was studied by electrophoretic mobility shift assays. RTPCR was performed to study expression of NF-κB mRNA. Results: Hydrogen peroxide led to apoptosis of SW-480 cells, condensed or semilunar chromatin even apoptotic bodies could be observed. Nuclear translocation of NF-κB,increase of NF-κB activity and expression of NF-κB mRNA were found simultaneously. Conclusions: Early activation of NF-κ B may be one of the mechanisms of apoptosis in intestinal epithelial cells by reactive oxygen species.

  17. Influence of Concentration and Activation on Hydrogen Peroxide Diffusion through Dental Tissues In Vitro

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    Carlos R. G. Torres

    2013-01-01

    Full Text Available This study evaluated the effect of physical and chemical activation on the diffusion time of different concentrations of hydrogen peroxide (HP bleaching agents through enamel and dentin. One hundred and twenty bovine cylindrical specimens were divided into six groups (n=20: 20% HP ; 20% HP with light activation; 20% HP with manganese gluconate; 35% HP; 35% HP with light activation; and 35% HP with manganese gluconate. The specimens were fixed over transparent epoxy wells with internal cavities to simulate a pulpal chamber. This chamber was filled with an enzymatic reagent to simulate pulpal fluid. The bleaching gels were applied on enamel surface and the image of the pulpal fluid was captured by a video camera to monitor the time of peroxide penetration in each specimen. ANOVA analysis showed that concentration and type of activation of bleaching gel significantly influenced the diffusion time of HP (P<0.05. 35% HP showed the lowest diffusion times compared to the groups with 20% HP gel. The light activation of HP decreased significantly the diffusion time compared to chemical activation. The highest diffusion time was obtained with 20% HP chemically activated. The diffusion time of HP was dependent on activation and concentration of HP. The higher concentration of HP diffused through dental tissues more quickly.

  18. Energy Efficient Catalytic Activation of Hydrogen peroxide for Green Chemical Processes: Final Report

    Energy Technology Data Exchange (ETDEWEB)

    Collins, Terrence J.; Horwitz, Colin

    2004-11-12

    A new, highly energy efficient approach for using catalytic oxidation chemistry in multiple fields of technology has been pursued. The new catalysts, called TAML® activators, catalyze the reactions of hydrogen peroxide and other oxidants for the exceptionally rapid decontamination of noninfectious simulants (B. atrophaeus) of anthrax spores, for the energy efficient decontamination of thiophosphate pesticides, for the facile, low temperature removal of color and organochlorines from pulp and paper mill effluent, for the bleaching of dyes from textile mill effluents, and for the removal of recalcitrant dibenzothiophene compounds from diesel and gasoline fuels. Highlights include the following: 1) A 7-log kill of Bacillus atrophaeus spores has been achieved unambiguously in water under ambient conditions within 15 minutes. 2) The rapid total degradation under ambient conditions of four thiophosphate pesticides and phosphonate degradation intermediates has been achieved on treatment with TAML/peroxide, opening up potential applications of the decontamination system for phosphonate structured chemical warfare agents, for inexpensive, easy to perform degradation of stored and aged pesticide stocks (especially in Africa and Asia), for remediation of polluted sites and water bodies, and for the destruction of chemical warfare agent stockpiles. 3) A mill trial conducted in a Pennsylvanian bleached kraft pulp mill has established that TAML catalyst injected into an alkaline peroxide bleach tower can significantly lower color from the effluent stream promising a new, more cost effective, energy-saving approach for color remediation adding further evidence of the value and diverse engineering capacity of the approach to other field trials conducted on effluent streams as they exit the bleach plant. 4) Dibenzothiophenes (DBTs), including 4,6-dimethyldibenzothiophene, the most recalcitrant sulfur compounds in diesel and gasoline, can be completely removed from model gasoline

  19. An in vitro thermal analysis during different light-activated hydrogen peroxide bleaching

    Science.gov (United States)

    Kabbach, W.; Zezell, D. M.; Bandéca, M. C.; Pereira, T. M.; Andrade, M. F.

    2010-09-01

    This study measured the critical temperature reaching time and also the variation of temperature in the surface of the cervical region and within the pulp chamber of human teeth submitted to dental bleaching using 35% hydrogen peroxide gel activated by three different light sources. The samples were randomly divided into 3 groups ( n = 15), according to the catalyst light source: Halogen Light (HL), High Intensity Diode Laser (DL), and Light Emmited Diode (LED). The results of temperature variation were submitted to the analysis of variance and Tukey test with p dental bleaching for a short period of time. The LED source did not heat the target tissues significantly within the parameters used in this study.

  20. Modulation of Na+/K+ ATPase Activity by Hydrogen Peroxide Generated through Heme in L. amazonensis.

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    Nathália Rocco-Machado

    Full Text Available Leishmania amazonensis is a protozoan parasite that occurs in many areas of Brazil and causes skin lesions. Using this parasite, our group showed the activation of Na+/K+ ATPase through a signaling cascade that involves the presence of heme and protein kinase C (PKC activity. Heme is an important biomolecule that has pro-oxidant activity and signaling capacity. Reactive oxygen species (ROS can act as second messengers, which are required in various signaling cascades. Our goal in this work is to investigate the role of hydrogen peroxide (H2O2 generated in the presence of heme in the Na+/K+ ATPase activity of L. amazonensis. Our results show that increasing concentrations of heme stimulates the production of H2O2 in a dose-dependent manner until a concentration of 2.5 μM heme. To confirm that the effect of heme on the Na+/K+ ATPase is through the generation of H2O2, we measured enzyme activity using increasing concentrations of H2O2 and, as expected, the activity increased in a dose-dependent manner until a concentration of 0.1 μM H2O2. To investigate the role of PKC in this signaling pathway, we observed the production of H2O2 in the presence of its activator phorbol 12-myristate 13-acetate (PMA and its inhibitor calphostin C. Both showed no effect on the generation of H2O2. Furthermore, we found that PKC activity is increased in the presence of H2O2, and that in the presence of calphostin C, H2O2 is unable to activate the Na+/K+ ATPase. 100 μM of Mito-TEMPO was capable of abolishing the stimulatory effect of heme on Na+/K+ ATPase activity, indicating that mitochondria might be the source of the hydrogen peroxide production induced by heme. The modulation of L. amazonensis Na+/K+ ATPase by H2O2 opens new possibilities for understanding the signaling pathways of this parasite.

  1. Modulation of Na+/K+ ATPase Activity by Hydrogen Peroxide Generated through Heme in L. amazonensis.

    Science.gov (United States)

    Rocco-Machado, Nathália; Cosentino-Gomes, Daniela; Meyer-Fernandes, José Roberto

    2015-01-01

    Leishmania amazonensis is a protozoan parasite that occurs in many areas of Brazil and causes skin lesions. Using this parasite, our group showed the activation of Na+/K+ ATPase through a signaling cascade that involves the presence of heme and protein kinase C (PKC) activity. Heme is an important biomolecule that has pro-oxidant activity and signaling capacity. Reactive oxygen species (ROS) can act as second messengers, which are required in various signaling cascades. Our goal in this work is to investigate the role of hydrogen peroxide (H2O2) generated in the presence of heme in the Na+/K+ ATPase activity of L. amazonensis. Our results show that increasing concentrations of heme stimulates the production of H2O2 in a dose-dependent manner until a concentration of 2.5 μM heme. To confirm that the effect of heme on the Na+/K+ ATPase is through the generation of H2O2, we measured enzyme activity using increasing concentrations of H2O2 and, as expected, the activity increased in a dose-dependent manner until a concentration of 0.1 μM H2O2. To investigate the role of PKC in this signaling pathway, we observed the production of H2O2 in the presence of its activator phorbol 12-myristate 13-acetate (PMA) and its inhibitor calphostin C. Both showed no effect on the generation of H2O2. Furthermore, we found that PKC activity is increased in the presence of H2O2, and that in the presence of calphostin C, H2O2 is unable to activate the Na+/K+ ATPase. 100 μM of Mito-TEMPO was capable of abolishing the stimulatory effect of heme on Na+/K+ ATPase activity, indicating that mitochondria might be the source of the hydrogen peroxide production induced by heme. The modulation of L. amazonensis Na+/K+ ATPase by H2O2 opens new possibilities for understanding the signaling pathways of this parasite. PMID:26070143

  2. Using a Hands-On Hydrogen Peroxide Decomposition Activity to Teach Catalysis Concepts to K-12 Students

    Science.gov (United States)

    Cybulskis, Viktor J.; Ribeiro, Fabio H.; Gounder, Rajamani

    2016-01-01

    A versatile and transportable laboratory apparatus was developed for middle and high school (6th-12th grade) students as part of a hands-on outreach activity to estimate catalytic rates of hydrogen peroxide decomposition from oxygen evolution rates measured by using a volumetric displacement method. The apparatus was constructed with inherent…

  3. Progress toward hydrogen peroxide micropulsion

    Energy Technology Data Exchange (ETDEWEB)

    Whitehead, J C; Dittman, M D; Ledebuhr, A G

    1999-07-08

    A new self-pressurizing propulsion system has liquid thrusters and gas jet attitude control without heavy gas storage vessels. A pump boosts the pressure of a small fraction of the hydrogen peroxide, so that reacted propellant can controllably pressurize its own source tank. The warm decomposition gas also powers the pump and is supplied to the attitude control jets. The system has been incorporated into a prototype microsatellite for terrestrial maneuvering tests. Additional progress includes preliminary testing of a bipropellant thruster, and storage of unstabilized hydrogen peroxide in small sealed tanks.

  4. Phospholipase A2 activation by hydrogen peroxide during in vitro capacitation of buffalo spermatozoa.

    Science.gov (United States)

    Shit, Sanjoy; Atreja, S K

    2004-05-01

    Progressively motile, washed buffalo spermatozoa (50 x 10(6) cells in 0.5 ml) were in vitro capacitated in HEPES containing Bovine Gamete Medium 3 (BGM3) in presence of heparin (10 microg/ml), and different concentrations of hydrogen peroxide (10 to 100 microM). Spermatozoa (60%) were capacitated in presence of heparin compared to 56% in presence of 25 microM H2O2 (optimally found suitable for capacitation). The extent of capacitation was measured in terms of acrosome reaction (AR) induced by lysophosphatidyl choline (100 microg/ml). The acrosome reacted cells were counted after triple staining. Catalase (100 microg/ml) significantly reduced the sperm capacitation to 16-18% when added with H2O2, or alone in the capacitation medium. Phospholipase A2 activity of spermatozoa increased linearly up to 50 microM H2O2 concentration included in the assay system. Moreover, significant increase in phospholipase A2 activity was observed after capacitation by both, the heparin and 25 microM H2O2. The activity was always higher in acrosome reacted cells. PMID:15233473

  5. Species and Organ Diversity in the Effects of Hydrogen Peroxide on Superoxide Dismutase Activity In Vitro

    Institute of Scientific and Technical Information of China (English)

    Hong-Yan Cheng; Song-Quan Song

    2006-01-01

    Superoxide dismutase (SOD) is ubiquitous in aerobic organisms and constitutes the first link in the enzyme scavenging system of reactive oxygen species. In the present study, species and organ diversity of SOD activity in a solution and in an in-gel assay system, as well as the effects of hydrogen peroxide (H2O2) on SOD activity, were investigated. In a solution assay system, SOD activity of jackfruit root, shoot, leaves, axes, and cotyledons, of maize embryos and endosperms, of mung bean leaves and seeds, of sacred lotus axes and cotyledons, and of rice and wheat leaves was increased by 1-15 mmol/L H2O2. However, SOD activity in rice root and seeds, maize roots and leaves, mung bean roots and shoots, and wheat seeds was decreased by 1-15 mmol/L H2O2. The SOD activity of wheat root and soybean roots, leaves, axes, and cotyledons was increased by 1-4 mmol/L H2O2, but was decreased by concentrations of H2O2 >4 mmol/L. The SOD activity of soybean shoots was not affected by 1-15 mmol/L H2O2. The SOD activity in crude mitochondria of jackfruit,maize, and upas seeds, as well as in purified mitochondria of jackfruit, was also increased by 1-15 mmol/L H2O2. In the in-gel assay system, the SOD in jackfruit cotyledons was comprised of Mn-SOD, Cu/Zn-SOD, and Fe-SOD, the crude mitochondria of jackfruit seeds and maizes embryo was comprised of Mn-SOD and Cu/Zn-SOD, and the crude mitochondria of maize seeds was comprised of Mn-SOD only. In the present study,H2O2 markedly inhibited Cu/Zn-SOD and Fe-SOD activity.

  6. PROCESS OPTIMIZATION OF TETRA ACETYL ETHYLENE DIAMINE ACTIVATED HYDROGEN PEROXIDE BLEACHING OF POPULUS NIGRA CTMP

    Directory of Open Access Journals (Sweden)

    Qiang Zhao

    2010-02-01

    Full Text Available To enhance the bleaching efficiency, the activator of tetra acetyl ethylene diamine (TAED was used in conventional H2O2 bleaching. The H2O2/TAED bleaching system can accelerate the reaction rate and shorten bleaching time at relative low temperature, which can reduce the production cost. In this research, the process with hydrogen peroxide activated by TAED bleaching of Populus nigra chemi-thermo mechanical pulp was optimized. Suitable bleaching conditions were confirmed as follows: pulp consistency 10%, bleaching temperature 70oC, bleaching time 60 min when the charge of H2O2 was 4%, NaOH charge 2%, and molar ratio of TAED to H2O2 0.3. The pulp brightness gain reached 23.6% ISO with the optimized bleaching conditions. FTIR analysis indicated that the H2O2/TAED bleaching system can decrease carbonyl group further than that of conventional H2O2 bleaching, which contributed to the higher bleaching efficiency and final brightness. The H2O2/TAED bleaching had stronger oxidation ability on lignin than that of H2O2 bleaching.

  7. Hydrogen peroxide sensing and cytotoxicity activity of Acacia lignin stabilized silver nanoparticles.

    Science.gov (United States)

    Aadil, Keshaw Ram; Barapatre, Anand; Meena, Avtar Singh; Jha, Harit

    2016-01-01

    The study is aimed at detection of hydrogen peroxide (H2O2) using Acacia lignin mediated silver nanoparticles (AGNPs). The synthesis of AGNPs was achieved at conditions optimized as, 3 ml of 0.02% lignin and 1mM silver nitrate incubated for 30 min at 80°C and pH 9. Initial screening of AGNPs was performed by measuring the surface plasmon resonance peak at 410-430 nm using UV-vis spectrophotometer. Transmission electron microscopy, atomic force microscopy, X-ray diffraction and particle size analysis confirmed the spherical shaped face centered cubic structure and 10-50 nm size of AGNPs. The infrared spectroscopy study further revealed that the active functional groups present in lignin were responsible for the reduction of silver ions (Ag(+)) to metallic silver (Ag(0)). Lignin stabilized silver nanoparticles showed good sensitivity and a linear response over wide concentrations of H2O2 (10(-1) to 10(-6)M). Further, the in vitrocytotoxicity activity of the lignin mediated AGNPs (5-500 μg/ml) demonstrated toxicity effects in MCF-7 and A375 cell lines. Thus, lignin stabilized silver nanoparticles based optical sensor for H2O2 could be potentially applied in the determination of reactive oxygen species and toxic chemicals which further expands the importance of lignin stabilized silver nanoparticles.

  8. Improved sensing response of photo activated ZnO thin film for hydrogen peroxide detection.

    Science.gov (United States)

    Parthasarathy, S; Nandhini, V; Jeyaprakash, B G

    2016-11-15

    The nanostructured ZnO thin films were deposited using spray pyrolysis technique. Formation of polycrystalinity with hexagonal wurtzite structure was observed from the structural study. Highly dense spherical shaped nanoparticles with fine crystallites were observed from the surface morphological studies. The light induced hydrogen peroxide vapour sensing was done using chemi-resistive method and its effect on the sensing response was studied and reported. PMID:27491004

  9. Hydrogen peroxide induces activation of insulin signaling pathway via AMP-dependent kinase in podocytes

    International Nuclear Information System (INIS)

    Highlights: ► H2O2 activates the insulin signaling pathway and glucose uptake in podocytes. ► H2O2 induces time-dependent changes in AMPK phosphorylation. ► H2O2 enhances insulin signaling pathways via AMPK activation. ► H2O2 stimulation of glucose uptake is AMPK-dependent. -- Abstract: Podocytes are cells that form the glomerular filtration barrier in the kidney. Insulin signaling in podocytes is critical for normal kidney function. Insulin signaling is regulated by oxidative stress and intracellular energy levels. We cultured rat podocytes to investigate the effects of hydrogen peroxide (H2O2) on the phosphorylation of proximal and distal elements of insulin signaling. We also investigated H2O2-induced intracellular changes in the distribution of protein kinase B (Akt). Western blots showed that H2O2 (100 μM) induced rapid, transient phosphorylation of the insulin receptor (IR), the IR substrate-1 (IRS1), and Akt with peak activities at 5 min (Δ 183%, P 2O2>. Furthermore, H2O2 inhibited phosphorylation of the phosphatase and tensin homologue (PTEN; peak activity at 10 min; Δ −32%, P 2O2 on IR phosphorylation by about 40% (from 2.07 ± 0.28 to 1.28 ± 0.12, P 2O2 increased glucose uptake in podocytes (from 0.88 ± 0.04 to 1.29 ± 0.12 nmol/min/mg protein, P 2O2 activated the insulin signaling pathway and glucose uptake via AMPK in cultured rat podocytes. This signaling may play a potential role in the prevention of insulin resistance under conditions associated with oxidative stress.

  10. 21 CFR 582.1366 - Hydrogen peroxide.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 6 2010-04-01 2010-04-01 false Hydrogen peroxide. 582.1366 Section 582.1366 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) ANIMAL... Additives § 582.1366 Hydrogen peroxide. (a) Product. Hydrogen peroxide. (b) (c) Limitations,...

  11. Hydrogen peroxide down-regulates inositol 1,4,5-trisphosphate receptor content through proteasome activation.

    Science.gov (United States)

    Martín-Garrido, A; Boyano-Adánez, M C; Alique, M; Calleros, L; Serrano, I; Griera, M; Rodríguez-Puyol, D; Griendling, K K; Rodríguez-Puyol, M

    2009-11-15

    Hydrogen peroxide (H(2)O(2)) is implicated in the regulation of signaling pathways leading to changes in vascular smooth muscle function. Contractile effects produced by H(2)O(2) are due to the phosphorylation of myosin light chain kinase triggered by increases in intracellular calcium (Ca(2+)) from intracellular stores or influx of extracellular Ca(2+). One mechanism for mobilizing such stores involves the phosphoinositide pathway. Inositol 1,4,5-trisphosphate (IP(3)) mobilizes intracellular Ca(2+) by binding to a family of receptors (IP(3)Rs) on the endoplasmic-sarcoplasmic reticulum that act as ligand-gated Ca(2+) channels. IP(3)Rs can be rapidly ubiquitinated and degraded by the proteasome, causing a decrease in cellular IP(3)R content. In this study we show that IP(3)R(1) and IP(3)R(3) are down-regulated when vascular smooth muscle cells (VSMC) are stimulated by H(2)O(2), through an increase in proteasome activity. Moreover, we demonstrate that the decrease in IP(3)R by H(2)O(2) is accompanied by a reduction in calcium efflux induced by IP(3) in VSMC. Also, we observed that angiotensin II (ANGII) induces a decrease in IP(3)R by activation of NADPH oxidase and that preincubation with H(2)O(2) decreases ANGII-mediated calcium efflux and planar cell surface area in VSMC. The decreased IP(3) receptor content observed in cells was also found in aortic rings, which exhibited a decreased ANGII-dependent contraction after treatment with H(2)O(2). Altogether, these results suggest that H(2)O(2) mediates IP(3)R down-regulation via proteasome activity.

  12. Effect of hydrogen peroxide on rabbit urinary bladder citrate synthase activity in the presence and absence of a grape suspension

    Directory of Open Access Journals (Sweden)

    Vijay Venugopal

    2010-12-01

    Full Text Available PURPOSE: The etiology of obstructive bladder dysfunction includes free radical damage to mitochondria. Feeding rabbits a standardized grape suspension protects the ability of the bladder to contract and empty in part by preventing mitochondrial damage, thus maintaining smooth muscle and mucosal metabolism. The objective of the current study is to determine the direct effect of this grape suspension on the response of mitochondria to the oxidative effects of hydrogen peroxide. MATERIALS AND METHODS: Six male rabbits were anesthetized with sodium pentobarbital and the bladders excised. Four full thickness strips were obtained for contractile studies and the balance separated into smooth muscle and mucosa compartments by blunt dissection. The effect of hydrogen peroxide on the contractile response to field stimulation was quantitated. Each tissue was homogenized and the effects of increasing concentrations of hydrogen peroxide in the presence and absence of grape suspension on citrate synthase activity was determined. RESULTS: Citrate synthase activity was significantly higher in the mucosa than in the muscle. The grape suspension had no effect on control citrate synthase activity. However, the grape suspension provided significant protection of both smooth muscle and mucosal citrate synthase activity. CONCLUSIONS: These studies support the conclusion that the grape suspension provides direct protection of mitochondrial function.

  13. Influence of chemical activation of a 35% hydrogen peroxide bleaching gel on its penetration and efficacy--in vitro study

    OpenAIRE

    Torres, C R G; Wiegand, A.; Sener, B.; Attin, T.

    2010-01-01

    OBJECTIVES: The aim of this study was to evaluate the effects of chemical activation of hydrogen peroxide (HP) gel on colour changes and penetration through the tooth structure. METHODS: One hundred and four bovine incisors were used. One dentine (CD) disc and one enamel-dentine (ED) disc were prepared from each tooth. They were positioned over artificial pulpal chambers and the bleaching was performed with an experimental 35% HP gel. Two control and six experimental groups were prepared. In ...

  14. Hydrogen peroxide mediates Rac1 activation of S6K1

    International Nuclear Information System (INIS)

    We previously reported that hydrogen peroxide (H2O2) mediates mitogen activation of ribosomal protein S6 kinase 1 (S6K1) which plays an important role in cell proliferation and growth. In this study, we investigated a possible role of H2O2 as a molecular linker in Rac1 activation of S6K1. Overexpression of recombinant catalase in NIH-3T3 cells led to the drastic inhibition of H2O2 production by PDGF, which was accompanied by a decrease in S6K1 activity. Similarly, PDGF activation of S6K1 was significantly inhibited by transient transfection or stable transfection of the cells with a dominant-negative Rac1 (Rac1N17), while overexpression of constitutively active Rac1 (Rac1V12) in the cells led to an increase in basal activity of S6K1. In addition, stable transfection of Rat2 cells with Rac1N17 dramatically attenuated the H2O2 production by PDGF as compared with that in the control cells. In contrast, Rat2 cells stably transfected with Rac1V12 produced high level of H2O2 in the absence of PDGF, comparable to that in the control cells stimulated with PDGF. More importantly, elimination of H2O2 produced in Rat2 cells overexpressing Rac1V12 inhibited the Rac1V12 activation of S6K1, indicating the possible role of H2O2 as a mediator in the activation of S6K1 by Rac1. However, H2O2 could be also produced via other pathway, which is independent of Rac1 or PI3K, because in Rat2 cells stably transfected with Rac1N17, H2O2 could be produced by arsenite, which has been shown to be a stimulator of H2O2 production. Taken together, these results suggest that H2O2 plays a pivotal role as a mediator in Rac1 activation of S6K1

  15. Diffused Intra-Oocyte Hydrogen Peroxide Activates Myeloperoxidase and Deteriorates Oocyte Quality.

    Directory of Open Access Journals (Sweden)

    Sana N Khan

    Full Text Available Hydrogen peroxide (H2O2 is a relatively long-lived signaling molecule that plays an essential role in oocyte maturation, implantation, as well as early embryonic development. Exposure to relatively high levels of H2O2 functions efficiently to accelerate oocyte aging and deteriorate oocyte quality. However, little precise information exists regarding intra-oocyte H2O2 concentrations, and its diffusion to the oocyte milieu. In this work, we utilized an L-shaped amperometric integrated H2O2-selective probe to directly and quantitatively measure the real-time intra-oocyte H2O2 concentration. This investigation provides an exact measurement of H2O2 in situ by reducing the possible loss of H2O2 caused by diffusion or reactivity with other biological systems. This experiment suggests that the intra-oocyte H2O2 levels of oocytes obtained from young animals are reasonably high and remained constant during the procedure measurements. However, the intra-oocyte H2O2 concentration dropped significantly (40-50% reduction in response to catalase pre-incubation, suggesting that the measurements are truly H2O2 based. To further confirm the extracellular diffusion of H2O2, oocytes were incubated with myeloperoxidase (MPO, and the diffused H2O2 triggered MPO chlorinating activity. Our results show that the generated hypochlorous acid (HOCl facilitated the deterioration in oocyte quality, a process that could be prevented by pre-incubating the oocytes with melatonin, which was experimentally proven to be oxidized utilizing HPLC methods. This study is the first to demonstrate direct quantitative measurement of intracellular H2O2, and its extracellular diffusion and activation of MPO as well as its impact on oocyte quality. These results may help in designing more accurate treatment plans in assisted reproduction under inflammatory conditions.

  16. 21 CFR 529.1150 - Hydrogen peroxide.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 6 2010-04-01 2010-04-01 false Hydrogen peroxide. 529.1150 Section 529.1150 Food... DRUGS, FEEDS, AND RELATED PRODUCTS CERTAIN OTHER DOSAGE FORM NEW ANIMAL DRUGS § 529.1150 Hydrogen peroxide. (a) Specifications. Each milliliter of solution contains 396.1 milligrams (mg) hydrogen...

  17. Hydrogen peroxide induces activation of insulin signaling pathway via AMP-dependent kinase in podocytes

    Energy Technology Data Exchange (ETDEWEB)

    Piwkowska, Agnieszka, E-mail: apiwkowska@cmdik.pan.pl [Mossakowski Medical Research Centre, Polish Academy of Sciences, Laboratory of Molecular and Cellular Nephrology, Gdansk (Poland); Rogacka, Dorota; Angielski, Stefan [Mossakowski Medical Research Centre, Polish Academy of Sciences, Laboratory of Molecular and Cellular Nephrology, Gdansk (Poland); Jankowski, Maciej [Mossakowski Medical Research Centre, Polish Academy of Sciences, Laboratory of Molecular and Cellular Nephrology, Gdansk (Poland); Medical University of Gdansk, Department of Therapy Monitoring and Pharmacogenetics (Poland)

    2012-11-09

    Highlights: Black-Right-Pointing-Pointer H{sub 2}O{sub 2} activates the insulin signaling pathway and glucose uptake in podocytes. Black-Right-Pointing-Pointer H{sub 2}O{sub 2} induces time-dependent changes in AMPK phosphorylation. Black-Right-Pointing-Pointer H{sub 2}O{sub 2} enhances insulin signaling pathways via AMPK activation. Black-Right-Pointing-Pointer H{sub 2}O{sub 2} stimulation of glucose uptake is AMPK-dependent. -- Abstract: Podocytes are cells that form the glomerular filtration barrier in the kidney. Insulin signaling in podocytes is critical for normal kidney function. Insulin signaling is regulated by oxidative stress and intracellular energy levels. We cultured rat podocytes to investigate the effects of hydrogen peroxide (H{sub 2}O{sub 2}) on the phosphorylation of proximal and distal elements of insulin signaling. We also investigated H{sub 2}O{sub 2}-induced intracellular changes in the distribution of protein kinase B (Akt). Western blots showed that H{sub 2}O{sub 2} (100 {mu}M) induced rapid, transient phosphorylation of the insulin receptor (IR), the IR substrate-1 (IRS1), and Akt with peak activities at 5 min ({Delta} 183%, P < 0.05), 3 min ({Delta} 414%, P < 0.05), and 10 min ({Delta} 35%, P < 0.05), respectively. Immunostaining cells with an Akt-specific antibody showed increased intensity at the plasma membrane after treatment with H{sub 2}O{sub 2}>. Furthermore, H{sub 2}O{sub 2} inhibited phosphorylation of the phosphatase and tensin homologue (PTEN; peak activity at 10 min; {Delta} -32%, P < 0.05) and stimulated phosphorylation of the AMP-dependent kinase alpha subunit (AMPK{alpha}; 78% at 3 min and 244% at 10 min). The stimulation of AMPK was abolished with an AMPK inhibitor, Compound C (100 {mu}M, 2 h). Moreover, Compound C significantly reduced the effect of H{sub 2}O{sub 2} on IR phosphorylation by about 40% (from 2.07 {+-} 0.28 to 1.28 {+-} 0.12, P < 0.05). In addition, H{sub 2}O{sub 2} increased glucose uptake in podocytes

  18. Hydrogen peroxide is a true first messenger.

    Science.gov (United States)

    Holmquist, L; Stuchbury, G; Steele, M; Münch, G

    2007-01-01

    Hydrogen peroxide has been shown to act as a second messenger mediating intracellular redox-sensitive signal transduction. Here we show that hydrogen peroxide is also able to transmit pro-inflammatory signals from one cell to the other and that this action can be inhibited by extracellularly added catalase. If these data can be further substantiated, hydrogen peroxide might become as important as nitric oxide as a small molecule intercellular (first) messenger.

  19. Optimized enzymatic colorimetric assay for determination of hydrogen peroxide (H2O2) scavenging activity of plant extracts

    OpenAIRE

    Chamira Dilanka Fernando; Preethi Soysa

    2015-01-01

    The classical method to determine hydrogen peroxide (H2O2) scavenging activity of plant extracts is evaluated by measuring the disappearance of H2O2 at a wavelength of 230 nm. Since this method suffers from the interference of phenolics having strong absorption in the UV region, a simple and rapid colorimetric assay was developed where plant extracts are introduced to H2O2, phenol and 4-aminoantipyrine reaction system in the presence of horseradish peroxidase (HRP). This reaction yields a qui...

  20. Activated carbon/Fe(3)O(4) nanoparticle composite: fabrication, methyl orange removal and regeneration by hydrogen peroxide.

    Science.gov (United States)

    Do, Manh Huy; Phan, Ngoc Hoa; Nguyen, Thi Dung; Pham, Thi Thu Suong; Nguyen, Van Khoa; Vu, Thi Thuy Trang; Nguyen, Thi Kim Phuong

    2011-11-01

    In the water treatment field, activated carbons (ACs) have wide applications in adsorptions. However, the applications are limited by difficulties encountered in separation and regeneration processes. Here, activated carbon/Fe(3)O(4) nanoparticle composites, which combine the adsorption features of powdered activated carbon (PAC) with the magnetic and excellent catalytic properties of Fe(3)O(4) nanoparticles, were fabricated by a modified impregnation method using HNO(3) as the carbon modifying agent. The obtained composites were characterized by X-ray diffraction, scanning and transmission electron microscopy, nitrogen adsorption isotherms and vibrating sample magnetometer. Their performance for methyl orange (MO) removal by adsorption was evaluated. The regeneration of the composite and PAC-HNO(3) (powdered activated carbon modified by HNO(3)) adsorbed MO by hydrogen peroxide was investigated. The composites had a high specific surface area and porosity and a superparamagnetic property that shows they can be manipulated by an external magnetic field. Adsorption experiments showed that the MO sorption process on the composites followed pseudo-second order kinetic model and the adsorption isotherm date could be simulated with both the Freundlich and Langmuir models. The regeneration indicated that the presence of the Fe(3)O(4) nanoparticles is important for a achieving high regeneration efficiency by hydrogen peroxide. PMID:21840037

  1. Functionalized Palladium Nanoparticles for Hydrogen Peroxide Biosensor

    Directory of Open Access Journals (Sweden)

    H. Baccar

    2011-01-01

    Full Text Available We present a comparison between two biosensors for hydrogen peroxide (H2O2 detection. The first biosensor was developed by the immobilization of Horseradish Peroxidase (HRP enzyme on thiol-modified gold electrode. The second biosensor was developed by the immobilization of cysteamine functionalizing palladium nanoparticles on modified gold surface. The amino groups can be activated with glutaraldehyde for horseradish peroxidase immobilization. The detection of hydrogen peroxide was successfully observed in PBS for both biosensors using the cyclic voltammetry and the chronoamperometry techniques. The results show that the limit detection depends on the large surface-to-volume ratio attained with palladium nanoparticles. The second biosensor presents a better detection limit of 7.5 μM in comparison with the first one which is equal to 75 μM.

  2. Effect of the Ascorbic Acid, Pyridoxine and Hydrogen Peroxide Treatments on Germination, Catalase Activity, Protein and Malondialdehyde Content of Three Oil Seeds

    Directory of Open Access Journals (Sweden)

    Aria DOLATABADIAN

    2008-08-01

    Full Text Available Oil seed production has an important role in human nutrition and industry. Success in oil plant cultivation is related to seed production with high viability and rapid germination, because these seeds rapidly loose their viability by fats oxidation. Thus, in this work we studied the effects of ascorbic acid, pyridoxine and hydrogen peroxide solutions on germination quantitative traits, catalase activity, protein and malondialdehyde content of three old oil seeds (sunflower, rape seed and safflower. The results showed that ascorbic acid and pyridoxine stimulated significantly the sunflower and rape seed germination. These vitamins, however, didn't have any effect on safflower germination. Hydrogen peroxide strongly increased safflower germination. Ascorbic acid and pyridoxine decreased catalase activity in sunflower and rape seed, whereas hydrogen peroxide increased it. Ascorbic acid and pyridoxine prevented protein degradation and lipid peroxidation in germinated seeds. Consequently, we understand that ascorbic acid and pyridoxine can increase sunflower and rape seed germination and stimulate rate of growth. Also safflower germination increased due to germination inhibitor oxidation by hydrogen peroxide. In conclusion, this report shows that oil seeds treated with ascorbic acid, pyridoxine and hydrogen peroxide remarkably increase the capacity of germination. We suggest that treatments with such substances can improve the old oil seed germination during storage.

  3. Hydrogen peroxide enteritis: the "snow white" sign.

    Science.gov (United States)

    Bilotta, J J; Waye, J D

    1989-01-01

    Hydrogen peroxide is a useful disinfectant that has achieved widespread utility in varied clinical settings. We report an epidemic of hydrogen peroxide enteritis that developed in seven patients in our gastrointestinal endoscopy unit during a 2-week period in early 1988. During endoscopy, using recently sterilized endoscopes that were flushed with 3% hydrogen peroxide after the glutaraldehyde cycle, instantaneous blanching (the "snow white" sign) and effervescence were noted on the mucosal surfaces when the water button was depressed. No patient subsequently suffered morbidity or mortality associated with this peroxide enteritis, and the biopsy specimens revealed nonspecific inflammation. The toxicity of hydrogen peroxide when used in enema form is reviewed, as well as the pathogenesis of peroxide enteritis.

  4. Hydrogen peroxide as a greenhouse soil amendment

    Science.gov (United States)

    There are anecdotal reports that hydrogen peroxide provides growth benefits beyond controlling plant infection and plant stress. The objective of this research was to determine the effect of soil applications of hydrogen peroxide solutions on plant growth and flowering. Nasturtium (Tropaeolum maju...

  5. 7 CFR 58.431 - Hydrogen peroxide.

    Science.gov (United States)

    2010-01-01

    ... 7 Agriculture 3 2010-01-01 2010-01-01 false Hydrogen peroxide. 58.431 Section 58.431 Agriculture Regulations of the Department of Agriculture (Continued) AGRICULTURAL MARKETING SERVICE (Standards... Material § 58.431 Hydrogen peroxide. The solution shall comply with the specification of the...

  6. Vapor Hydrogen Peroxide Sterilization Certification

    Science.gov (United States)

    Chen, Fei; Chung, Shirley; Barengoltz, Jack

    For interplanetary missions landing on a planet of potential biological interest, United States NASA planetary protection currently requires that the flight system must be assembled, tested and ultimately launched with the intent of minimizing the bioload taken to and deposited on the planet. Currently the only NASA approved microbial reduction method is dry heat sterilization process. However, with utilization of such elements as highly sophisticated electronics and sensors in modern spacecraft, this process presents significant materials challenges and is thus an undesirable bioburden reduction method to design engineers. The objective of this work is to introduce vapor hydrogen peroxide (VHP) as an alternative to dry heat microbial reduction to meet planetary protection requirements. The VHP sterilization technology is widely used by the medical industry, but high doses of VHP may degrade the performance of flight hardware, or compromise material compatibility. The goal of our study is determine the minimum VHP process conditions for PP acceptable microbial reduction levels. A series of experiments were conducted using Geobacillus stearothermophilus to determine VHP process parameters that provided significant reductions in spore viability while allowing survival of sufficient spores for statistically significant enumeration. In addition to the obvious process parameters -hydrogen peroxide concentration, number of pulses, and exposure duration -the investigation also considered the possible effect of environmental pa-rameters. Temperature, relative humidity, and material substrate effects on lethality were also studied. Based on the results, a most conservative D value was recommended. This recom-mended D value was also validated using VHP "hardy" strains that were isolated from clean-rooms and environmental populations collected from spacecraft relevant areas. The efficiency of VHP at ambient condition as well as VHP material compatibility will also be

  7. Evaluation of anti-apoptotic activity of different dietary antioxidants in renal cell carcinoma against hydrogen peroxide

    Institute of Scientific and Technical Information of China (English)

    Garg Neeraj K; Mangal Sharad; Sahu Tejram; Mehta Abhinav; Vyas Suresh P; Tyagi Rajeev K

    2011-01-01

    Objective: To evaluate the anti-apoptotic and radical scavenging activities of dietary phenolics, namely ascorbic acid, -tocopherol acetate, citric acid, salicylic acid, and estimate H2O2-induced apoptosis in renal cell carcinoma cells. Methods: The intracellular antioxidant potency of antioxidants was investigated. H2O2-induced apoptosis in RCC-26 was assayed with the following parameters: cell viability (% apoptosis), nucleosomal damage and DNA fragmentation, bcl-2 levels and flow cytometery analysis (ROS production evaluation). Results: The anticancer properties of antioxidants such as ascorbic acid, - tocopherol acetate, citric acid, salicylic acid with perdurable responses were investigated. It was observed that these antioxidants had protective effect (anti-apoptotic activity) against hydrogen peroxide (H2O2) in renal cell carcinoma (RCC-26) cell line. Conclusions: This study reveals and proves the anticancer properties. However, in cancer cell lines anti-apoptotic activity can indirectly reflect the cancer promoter activity through radicals scavenging, and significantly protect nucleus and bcl-2.

  8. Catalytic oxidative desulfurization of diesel utilizing hydrogen peroxide and functionalized-activated carbon in a biphasic diesel-acetonitrile system

    Energy Technology Data Exchange (ETDEWEB)

    Haw, Kok-Giap; Bakar, Wan Azelee Wan Abu; Ali, Rusmidah; Chong, Jiunn-Fat [Department of Chemistry, Faculty of Science, Universiti Teknologi Malaysia, 81310 UTM Skudai, Johor (Malaysia); Kadir, Abdul Aziz Abdul [Department of Petroleum Engineering, Faculty of Chemical and Natural Resources Engineering, Universiti Teknologi Malaysia, 81310 UTM Skudai, Johor (Malaysia)

    2010-09-15

    This paper presents the development of granular functionalized-activated carbon as catalysts in the catalytic oxidative desulfurization (Cat-ODS) of commercial Malaysian diesel using hydrogen peroxide as oxidant. Granular functionalized-activated carbon was prepared from oil palm shell using phosphoric acid activation method and carbonized at 500 C and 700 C for 1 h. The activated carbons were characterized using various analytical techniques to study the chemistry underlying the preparation and calcination treatment. Nitrogen adsorption/desorption isotherms exhibited the characteristic of microporous structure with some contribution of mesopore property. The Fourier Transform Infrared Spectroscopy results showed that higher activation temperature leads to fewer surface functional groups due to thermal decomposition. Micrograph from Field Emission Scanning Electron Microscope showed that activation at 700 C creates orderly and well developed pores. Furthermore, X-ray Diffraction patterns revealed that pyrolysis has converted crystalline cellulose structure of oil palm shell to amorphous carbon structure. The influence of the reaction temperature, the oxidation duration, the solvent, and the oxidant/sulfur molar ratio were examined. The rates of the catalytic oxidative desulfurization reaction were found to increase with the temperature, and H{sub 2}O{sub 2}/S molar ratio. Under the best operating condition for the catalytic oxidative desulfurization: temperature 50 C, atmospheric pressure, 0.5 g activated carbon, 3 mol ratio of hydrogen peroxide to sulfur, 2 mol ratio of acetic acid to sulfur, 3 oxidation cycles with 1 h for each cycle using acetonitrile as extraction solvent, the sulfur content in diesel was reduced from 2189 ppm to 190 ppm with 91.3% of total sulfur removed. (author)

  9. Detection of hydrogen peroxide with chemiluminescent micelles

    Directory of Open Access Journals (Sweden)

    Dongwon Lee

    2008-08-01

    Full Text Available Dongwon Lee1, Venkata R Erigala1,3, Madhuri Dasari1, Junhua Yu2, Robert M Dickson2, Niren Murthy11The Wallace H. Coulter Department of Biomedical Engineering; 2Department of Chemistry and Biochemistry, Georgia Institute of Technology, Atlanta, GA, USA; 3The Scripps Research Institute, La Jolla, CA, USAAbstract: The overproduction of hydrogen peroxide is implicated in the progress of numerous life-threatening diseases and there is a great need for the development of contrast agents that can detect hydrogen peroxide in vivo. In this communication, we present a new contrast agent for hydrogen peroxide, termed peroxalate micelles, which detect hydrogen peroxide through chemiluminescence, and have the physical/chemical properties needed for in vivo imaging applications. The peroxalate micelles are composed of amphiphilic peroxalate based copolymers and the fluorescent dye rubrene, they have a ‘stealth’ polyethylene glycol (PEG corona to evade macrophage phagocytosis, and a diameter of 33 nm to enhance extravasation into permeable tissues. The peroxalate micelles can detect nanomolar concentrations of hydrogen peroxide (>50 nM and thus have the sensitivity needed to detect physiological concentrations of hydrogen peroxide. We anticipate numerous applications of the peroxalate micelles for in vivo imaging of hydrogen peroxide, given their high sensitivity, small size, and biocompatible PEG corona.Keywords: hydrogen peroixde, chemiluminescence, micelles, amphiphilic copolymer

  10. The effect of water deficit on the activity of hydrogen peroxide-scavenging enzymes in two barley genotypes

    Directory of Open Access Journals (Sweden)

    Hanna Bandurska

    2014-02-01

    Full Text Available Two barley (Hordeum vulgare L. genotypes, the cv. Aramir and line R567, were subjected to water deficit by immersing their root systems in polyethylene glycol solution of osmotic potential -1.0 MPa. The stress caused a decline in the leaf-relative-water content (RWC and affected membrane damage in both the genotypes. A higher decline in RWC and a higher membrane injury index was observed in R567 in comparison to 'Aramir'. Water deficit induced an increase in the activity of guaiacol peroxidase (GPO and catalse (CAT. A higher increase of CAT than GPO peroxidase activity has been noted in both the genotypes. The results. together with our earlier reports (Bandurska et al. 1997 show that detoxification of hydrogen peroxide under water stress conditions in those two barley genotypes was associated with the action of GPO and CAT, and that the latter was more involved in that process.

  11. Membrane transport of hydrogen peroxide.

    Science.gov (United States)

    Bienert, Gerd P; Schjoerring, Jan K; Jahn, Thomas P

    2006-08-01

    Hydrogen peroxide (H2O2) belongs to the reactive oxygen species (ROS), known as oxidants that can react with various cellular targets thereby causing cell damage or even cell death. On the other hand, recent work has demonstrated that H2O2 also functions as a signalling molecule controlling different essential processes in plants and mammals. Because of these opposing functions the cellular level of H2O2 is likely to be subjected to tight regulation via processes involved in production, distribution and removal. Substantial progress has been made exploring the formation and scavenging of H2O2, whereas little is known about how this signal molecule is transported from its site of origin to the place of action or detoxification. From work in yeast and bacteria it is clear that the diffusion of H2O2 across membranes is limited. We have now obtained direct evidence that selected aquaporin homologues from plants and mammals have the capacity to channel H2O2 across membranes. The main focus of this review is (i) to summarize the most recent evidence for a signalling role of H2O2 in various pathways in plants and mammals and (ii) to discuss the relevance of specific transport of H2O2.

  12. Detection of interstellar hydrogen peroxide

    CERN Document Server

    Bergman, P; Liseau, R; Larsson, B; Olofsson, H; Menten, K M; Güsten, R

    2011-01-01

    The molecular species hydrogen peroxide, HOOH, is likely to be a key ingredient in the oxygen and water chemistry in the interstellar medium. Our aim with this investigation is to determine how abundant HOOH is in the cloud core {\\rho} Oph A. By observing several transitions of HOOH in the (sub)millimeter regime we seek to identify the molecule and also to determine the excitation conditions through a multilevel excitation analysis. We have detected three spectral lines toward the SM1 position of {\\rho} Oph A at velocity-corrected frequencies that coincide very closely with those measured from laboratory spectroscopy of HOOH. A fourth line was detected at the 4{\\sigma} level. We also found through mapping observations that the HOOH emission extends (about 0.05 pc) over the densest part of the {\\rho} Oph A cloud core. We derive an abundance of HOOH relative to that of H_2 in the SM1 core of about 1\\times10^(-10). To our knowledge, this is the first reported detection of HOOH in the interstellar medium.

  13. Cell survival of glioblastoma grown in medium containing hydrogen peroxide and/or nitrite, or in plasma-activated medium.

    Science.gov (United States)

    Kurake, Naoyuki; Tanaka, Hiromasa; Ishikawa, Kenji; Kondo, Takashi; Sekine, Makoto; Nakamura, Kae; Kajiyama, Hiroaki; Kikkawa, Fumitaka; Mizuno, Masaaki; Hori, Masaru

    2016-09-01

    Non-equilibrium atmospheric pressure plasmas generate a high electron density (on the order of 10(16) electrons per cm(-3)) using Ar gas. Culture medium in air at room temperature was plasma-irradiated for several hundred seconds. Tens of micromolar hydrogen peroxide (H2O2) and millimolar levels of nitrous ion (NO2(-)) were detected in the plasma-irradiated culture medium (plasma activated medium; PAM) and selectively induced the apoptotic death of glioblastoma tumor cells, but did not kill normal mammary epithelial cells. A similar antitumor effect was induced by spiking the medium with comparable concentrations of H2O2 and NO2(-). The PAM remained still a somewhat difference that it should also be assessed for understanding other latent mechanisms. PMID:26820218

  14. Hydrogen Peroxide as a Sustainable Energy Carrier: Electrocatalytic Production of Hydrogen Peroxide and the Fuel Cell

    Science.gov (United States)

    Fukuzumi, Shunichi; Yamada, Yusuke; Karlin, Kenneth D.

    2012-01-01

    This review describes homogeneous and heterogeneous catalytic reduction of dioxygen with metal complexes focusing on the catalytic two-electron reduction of dioxygen to produce hydrogen peroxide. Whether two-electron reduction of dioxygen to produce hydrogen peroxide or four-electron O2-reduction to produce water occurs depends on the types of metals and ligands that are utilized. Those factors controlling the two processes are discussed in terms of metal-oxygen intermediates involved in the catalysis. Metal complexes acting as catalysts for selective two-electron reduction of oxygen can be utilized as metal complex-modified electrodes in the electrocatalytic reduction to produce hydrogen peroxide. Hydrogen peroxide thus produced can be used as a fuel in a hydrogen peroxide fuel cell. A hydrogen peroxide fuel cell can be operated with a one-compartment structure without a membrane, which is certainly more promising for the development of low-cost fuel cells as compared with two compartment hydrogen fuel cells that require membranes. Hydrogen peroxide is regarded as an environmentally benign energy carrier because it can be produced by the electrocatalytic two-electron reduction of O2, which is abundant in air, using solar cells; the hydrogen peroxide thus produced could then be readily stored and then used as needed to generate electricity through the use of hydrogen peroxide fuel cells. PMID:23457415

  15. Hydrogen Peroxide as a Sustainable Energy Carrier: Electrocatalytic Production of Hydrogen Peroxide and the Fuel Cell.

    Science.gov (United States)

    Fukuzumi, Shunichi; Yamada, Yusuke; Karlin, Kenneth D

    2012-11-01

    This review describes homogeneous and heterogeneous catalytic reduction of dioxygen with metal complexes focusing on the catalytic two-electron reduction of dioxygen to produce hydrogen peroxide. Whether two-electron reduction of dioxygen to produce hydrogen peroxide or four-electron O2-reduction to produce water occurs depends on the types of metals and ligands that are utilized. Those factors controlling the two processes are discussed in terms of metal-oxygen intermediates involved in the catalysis. Metal complexes acting as catalysts for selective two-electron reduction of oxygen can be utilized as metal complex-modified electrodes in the electrocatalytic reduction to produce hydrogen peroxide. Hydrogen peroxide thus produced can be used as a fuel in a hydrogen peroxide fuel cell. A hydrogen peroxide fuel cell can be operated with a one-compartment structure without a membrane, which is certainly more promising for the development of low-cost fuel cells as compared with two compartment hydrogen fuel cells that require membranes. Hydrogen peroxide is regarded as an environmentally benign energy carrier because it can be produced by the electrocatalytic two-electron reduction of O2, which is abundant in air, using solar cells; the hydrogen peroxide thus produced could then be readily stored and then used as needed to generate electricity through the use of hydrogen peroxide fuel cells.

  16. Hydrogen peroxide as a sustainable energy carrier: Electrocatalytic production of hydrogen peroxide and the fuel cell

    International Nuclear Information System (INIS)

    This review describes homogeneous and heterogeneous catalytic reduction of dioxygen with metal complexes focusing on the catalytic two-electron reduction of dioxygen to produce hydrogen peroxide. Whether two-electron reduction of dioxygen to produce hydrogen peroxide or four-electron O2-reduction to produce water occurs depends on the types of metals and ligands that are utilized. Those factors controlling the two processes are discussed in terms of metal–oxygen intermediates involved in the catalysis. Metal complexes acting as catalysts for selective two-electron reduction of oxygen can be utilized as metal complex-modified electrodes in the electrocatalytic reduction to produce hydrogen peroxide. Hydrogen peroxide thus produced can be used as a fuel in a hydrogen peroxide fuel cell. A hydrogen peroxide fuel cell can be operated with a one-compartment structure without a membrane, which is certainly more promising for the development of low-cost fuel cells as compared with two compartment hydrogen fuel cells that require membranes. Hydrogen peroxide is regarded as an environmentally benign energy carrier because it can be produced by the electrocatalytic two-electron reduction of O2, which is abundant in air, using solar cells; the hydrogen peroxide thus produced could then be readily stored and then used as needed to generate electricity through the use of hydrogen peroxide fuel cells.

  17. Mechanisms of wet oxidation by hydrogen peroxide

    International Nuclear Information System (INIS)

    A research programme is currently under way at BNL and MEL to investigate the possible use of Hydrogen Peroxide with metal ion catalysts as a wet oxidation treatment system for CEGB organic radioactive wastes. The published literature relating to the kinetics and mechanism of oxidation and decomposition reactions of hydrogen peroxide is reviewed and the links with practical waste management by wet oxidation are examined. Alternative wet oxidation systems are described and the similarities to the CEGB research effort are noted. (author)

  18. Electrolytic process for producing hydrogen peroxide

    International Nuclear Information System (INIS)

    An electrolytic process for producing hydrogen peroxide in an aqueous alkaline solution includes simultaneously passing an aqueous alkaline electrolyte and oxygen through a fluid permeable conductive cathode comprising reticulated vitreous carbon foam, separating the fluid permeable conductive cathode from an anode by a barrier and connecting the fluid permeable conductive electrode and the anode with an external power source to cause generation of hydrogen peroxide ion within the aqueous alkaline solution

  19. [Hydrogen peroxide in artificial photosynthesizing systems].

    Science.gov (United States)

    Lobanov, A V; Komissarov, G G

    2014-01-01

    From the point of view of the concepts of hydrogen peroxide as a source of photosynthetic oxygen (hydrogen) coordination and photochemical properties of chlorophyll and its aggregates towards hydrogen peroxide were considered. The binding energy of H2O and H2O2 with chlorophyll and chlorophyllide depending on their form (monomers, dimers and trimers) was estimated by quantum chemical calculations. It is shown that at an increase of the degree of the pigment aggregation binding energy of H2O2 was more than the energy of H2O. Analysis of experimental results of the photochemical decomposition of hydrogen peroxide using chlorophyll was carried out. Estimates of the thermodynamic parameters (deltaG degrees and deltaH degrees) of the formation of organic compounds from CO2 with water and hydrogen peroxide were compared. The interaction of CO2 with H2O2 requires much less energy consumption than with water for all considered cases. The formation of organic products (formaldehyde, alcohols, carboxylic and carbonylic compounds) and simultaneous production of O2 under the influence of visible light in the systems of inorganic carbon--hydrogen peroxide--chlorophyll (phthalocyanine) is detected by GC/MS method, FTIR spectroscopy, and chemical analysis. PMID:25702472

  20. Homocysteine thiolactone induces apoptotic DNA damage mediated by increased intracellular hydrogen peroxide and caspase 3 activation in HL-60 cells.

    Science.gov (United States)

    Huang, R F; Huang, S M; Lin, B S; Wei, J S; Liu, T Z

    2001-05-11

    The cytotoxicity of homocysteine derivatives on chromosomal damage in somatic cells is not well established. The present study used reactive homocysteine derivative of homocysteine thiolactone (Hcy) to investigate its causal effect on apoptotic DNA injury in human promyeloid HL-60 cells. Our results demonstrated that Hcy induced cell death and features of apoptosis including increased phosphotidylserine exposure on the membrane surface, increased apoptotic cells with hypoploid DNA contents, and internucleosomal DNA fragmentation, all of which occurred in a time- and concentration-dependent manner. Hcy treatment also significantly increased intracellular reactive oxygen species H2O2, which coincided with the elimination of caspase 3 proenzyme levels and increased caspase 3 activity at the time of the appearance of apoptotic DNA fragmentation. Preincubation of Hcy-treated HL-60 cells with catalase completely scavenged intracellular H2O2, thus inhibiting caspase 3 activity and protecting cells from apoptotic DNA damage. In contrast, superoxide dismutase failed to inhibit Hcy-induced DNA damage. Taken together, these results demonstrate that Hcy exerted its genotoxic effects on HL-60 cells through an apoptotic pathway, which is mediated by the activation of caspase 3 activity induced by an increase in intracellular hydrogen peroxide. PMID:11432446

  1. Cyclic ADP-ribose and hydrogen peroxide synergize with ADP-ribose in the activation of TRPM2 channels.

    Science.gov (United States)

    Kolisek, Martin; Beck, Andreas; Fleig, Andrea; Penner, Reinhold

    2005-04-01

    The melastatin-related transient receptor potential channel TRPM2 is a plasma membrane Ca2+-permeable cation channel that is activated by intracellular adenosine diphosphoribose (ADPR) binding to the channel's enzymatic Nudix domain. Channel activity is also seen with nicotinamide dinucleotide (NAD+) and hydrogen peroxide (H2O2), but their mechanisms of action remain unknown. Here, we identify cyclic adenosine diphosphoribose (cADPR) as an agonist of TRPM2 with dual activity: at concentrations above 100 microM, cADPR can gate the channel by itself, whereas lower concentrations of 10 microM have a potentiating effect that enables ADPR to gate the channel at nanomolar concentrations. ADPR's breakdown product adenosine monophosphate (AMP) specifically inhibits ADPR, but not cADPR-mediated gating of TRPM2, whereas the cADPR antagonist 8-Br-cADPR exhibits the reverse block specificity. Our results establish TRPM2 as a coincidence detector for ADPR and cADPR signaling and provide a functional context for cADPR as a second messenger for Ca2+ influx.

  2. Hexose Oxidase-Mediated Hydrogen Peroxide as a Mechanism for the Antibacterial Activity in the Red Seaweed Ptilophora subcostata.

    Science.gov (United States)

    Ogasawara, Kimi; Yamada, Kenji; Hatsugai, Noriyuki; Imada, Chiaki; Nishimura, Mikio

    2016-01-01

    Marine algae have unique defense strategies against microbial infection. However, their mechanisms of immunity remain to be elucidated and little is known about the similarity of the immune systems of marine algae and terrestrial higher plants. Here, we suggest a possible mechanism underlying algal immunity, which involves hexose oxidase (HOX)-dependent production of hydrogen peroxide (H2O2). We examined crude extracts from five different red algal species for their ability to prevent bacterial growth. The extract from one of these algae, Ptilophora subcostata, was particularly active and prevented the growth of gram-positive and -negative bacteria, which was completely inhibited by treatment with catalase. The extract did not affect the growth of either a yeast or a filamentous fungus. We partially purified from P. subcostata an enzyme involved in its antibacterial activity, which shared 50% homology with the HOX of red seaweed Chondrus crispus. In-gel carbohydrate oxidase assays revealed that P. subcostata extract had the ability to produce H2O2 in a hexose-dependent manner and this activity was highest in the presence of galactose. In addition, Bacillus subtilis growth was strongly suppressed near P. subcostata algal fronds on GYP agar plates. These results suggest that HOX plays a role in P. subcostata resistance to bacterial attack by mediating H2O2 production in the marine environment. PMID:26867214

  3. Hexose Oxidase-Mediated Hydrogen Peroxide as a Mechanism for the Antibacterial Activity in the Red Seaweed Ptilophora subcostata.

    Directory of Open Access Journals (Sweden)

    Kimi Ogasawara

    Full Text Available Marine algae have unique defense strategies against microbial infection. However, their mechanisms of immunity remain to be elucidated and little is known about the similarity of the immune systems of marine algae and terrestrial higher plants. Here, we suggest a possible mechanism underlying algal immunity, which involves hexose oxidase (HOX-dependent production of hydrogen peroxide (H2O2. We examined crude extracts from five different red algal species for their ability to prevent bacterial growth. The extract from one of these algae, Ptilophora subcostata, was particularly active and prevented the growth of gram-positive and -negative bacteria, which was completely inhibited by treatment with catalase. The extract did not affect the growth of either a yeast or a filamentous fungus. We partially purified from P. subcostata an enzyme involved in its antibacterial activity, which shared 50% homology with the HOX of red seaweed Chondrus crispus. In-gel carbohydrate oxidase assays revealed that P. subcostata extract had the ability to produce H2O2 in a hexose-dependent manner and this activity was highest in the presence of galactose. In addition, Bacillus subtilis growth was strongly suppressed near P. subcostata algal fronds on GYP agar plates. These results suggest that HOX plays a role in P. subcostata resistance to bacterial attack by mediating H2O2 production in the marine environment.

  4. Activation and involvement of JNK1 / 2 in hydrogen peroxide- induced neurotoxicity in cultured rat cortical neurons

    Institute of Scientific and Technical Information of China (English)

    Wei WANG; Can GAO; Xiao-yu HOU; Yong LIU; Yan-yan ZONG; Guang-yi ZHANG

    2004-01-01

    AIM: To investigate the role of c-Jun N-terminal protein kinase 1 and 2 (JNK1/2) and the main signal pathway for its activation in hydrogen peroxide (H2O2) induced apoptotic-like cortical cell death. METHODS: Using the model of oxidative stress induced by H2O2, the expression and diphosphorylation of JNK1/2 was examined by immunoblotting analysis, and neuronal apoptotic like cell death was determined by 4',6-diamidino-2-phenylindole (DAPI) staining.RESULTS: The elevation in diphosphorylation level of JNK1/2 (4.40-/5.61-fold vs sham control) was associated with the concentration of H2O2 (0-100 μmol/L) and the development of apoptotic-like cell death (11.04 %-81.01%).There was no alteration of JNK1/2 protein expression following H2O2 treatment and recovery at different time points. Administration with JNK1/2 antisense oligonucleotides not only significantly decreased JNK1/2 protein expression and activation level, but also significantly reduced cortical cell death induced by H2O2 exposure.Furthermore, both JNK1/2 diphosphorylation and apoptotic-like cell death were largely prevented by pretreatment with (5S, l0R)-(-)-5-methyl-10,11-dihydro-5H-dibenzo[a,d]cyclohepten-5,10-imine hydrogen maleate (MK-801)or omission of Ca2+ in incubation medium with ethylene glycol-bis(2-aminoethylether)-N,N,N',N-tetraacetic acid (EGTA). CONCLUSION: JNK1/2 is activated and participates in H2O2-induced apoptotic-like death in cultured rat cortical neurons mainly via N-methyl-D-aspartate (NMDA) receptor-mediated influx of extracellular Ca2+.

  5. Locating bomb factories by detecting hydrogen peroxide.

    Science.gov (United States)

    Romolo, Francesco Saverio; Connell, Samantha; Ferrari, Carlotta; Suarez, Guillaume; Sauvain, Jean-Jacques; Hopf, Nancy B

    2016-11-01

    The analytical capability to detect hydrogen peroxide vapour can play a key role in localizing a site where a H2O2 based Improvised Explosive (IE) is manufactured. In security activities it is very important to obtain information in a short time. For this reason, an analytical method to be used in security activity needs portable devices. The authors have developed the first analytical method based on a portable luminometer, specifically designed and validated to locate IE manufacturing sites using quantitative on-site vapour analysis for H2O2. The method was tested both indoor and outdoor. The results demonstrate that the detection of H2O2 vapours could allow police forces to locate the site, while terrorists are preparing an attack. The collected data are also very important in developing new sensors, able to give an early alarm if located at a proper distance from a site where an H2O2 based IE is prepared.

  6. Polypyrrole-hemin-reduce graphene oxide: rapid synthesis and enhanced electrocatalytic activity towards the reduction of hydrogen peroxide

    International Nuclear Information System (INIS)

    An efficient and eco-friendly microwave-assistant method is developed to synthesize a ternary composite of polypyrrole-hemin-reduced graphene oxide (PPY-He-RGO). The polymerization of the pyrrole monomer and the reduction of graphene oxide are performed simply by microwave heating without using a strong reducing or oxidizing agent in an isopropanol/H2O mixed medium. Hemin molecules are immobilized on reduced graphene oxide (RGO) sheets and can still retain high electrocatalytic activity toward the reduction of H2O2 in the final composite. The conducting RGO and polypyrrole with a well-controlled nanostructure provide a highly conductive network to the ternary composite, which can promote the electron transfer between hemin, analytes and electrodes, leading to an improved electrocatalytic activity. The PPY-He-RGO can act as a third-generation mediator and mimic enzyme for the fabrication of a hydrogen peroxide biosensor. The as-prepared PPY-He-RGO electrode exhibits a high sensitivity to H2O2 with a low detection limit of 0.13 μm. The efficient microwave heating provides an opportunity for large-scale production of PPY-He-RGO ternary nanocomposites as a kind of mimic enzyme for biosensors. (paper)

  7. Thiosulfate-Hydrogen Peroxide Redox Oscillator as pH Driver for Ribozyme Activity in the RNA World.

    Science.gov (United States)

    Ball, Rowena; Brindley, John

    2016-03-01

    The RNA world of more than 3.7 billion years ago may have drawn on thermal and pH oscillations set up by the oxidation of thiosulfate by hydrogen peroxide (the THP oscillator) as a power source to drive replication. Since this primordial RNA also must have developed enzyme functionalities, in this work we examine the responses of two simple ribozymes to a THP periodic drive, using experimental rate and thermochemical data in a dynamical model for the coupled, self-consistent evolution of all reactants and intermediates. The resulting time traces show that ribozyme performance can be enhanced under pH cycling, and that thermal cycling may have been necessary to achieve large performance gains. We discuss three important ways in which the dynamic hydrogen peroxide medium may have acted as an agent for development of the RNA world towards a cellular world: proton gradients, resolution of the ribozyme versus replication paradox, and vesicle formation.

  8. Catalytic activity of iron hexacyanoosmate(II) towards hydrogen peroxide and nicotinamide adenine dinucleotide and its use in amperometric biosensors

    Energy Technology Data Exchange (ETDEWEB)

    Kotzian, Petr; Janku, Tereza [Department of Analytical Chemistry, University of Pardubice, Nam. Cs. Legii 565, CZ-532 10 Pardubice (Czech Republic); Kalcher, Kurt [Institute of Chemistry - Analytical Chemistry, Karl-Franzens University, Universitaetsplatz 1, A-8010 Graz (Austria); Vytras, Karel [Department of Analytical Chemistry, University of Pardubice, Nam. Cs. Legii 565, CZ-532 10 Pardubice (Czech Republic)], E-mail: karel.vytras@upce.cz

    2007-09-19

    Hydrogen peroxide and nicotinamide adenine dinucleotide (NADH) may be determined amperometrically using screen-printed electrodes chemically modified with iron(III) hexacyanoosmate(II) (Osmium purple) in flow injection analysis (FIA). The determination is based on the exploitation of catalytic currents resulting from the oxidation/reduction of the modifier. The performance of the sensor was characterized and optimized by controlling several operational parameters (applied potential, pH and flow rate of the phosphate buffer). Comparison has been made with analogous complexes of ruthenium (Ruthenium purple) and iron (Prussian blue). Taking into account the sensitivity and stability of corresponding sensors, the best results were obtained with the use of Osmium purple. The sensor exhibited a linear increase of the amperometric signal with the concentration of hydrogen peroxide in the range of 0.1-100 mg L{sup -1} with a detection limit (evaluated as 3{sigma}) of 0.024 mg L{sup -1} with a R.S.D. 1.5% for 10 mg L{sup -1} H{sub 2}O{sub 2} under optimized flow rate of 0.4 mL min{sup -1} in 0.1 M phosphate buffer carrier (pH 6) and a working potential of +0.15 V versus Ag/AgCl. Afterwards, a biological recognition element - either glucose oxidase or ethanol dehydrogenase - was incorporated to achieve a sensor facilitating the determination of glucose or ethanol, respectively. The glucose sensor gave linearity between current and concentration in the range from 1 to 250 mg L{sup -1} with a R.S.D. 2.4% for 100 mg L{sup -1} glucose, detection limit 0.02 mg L{sup -1} (3{sigma}) and retained its original activity after 3 weeks when stored at 6 deg. C. Optimal parameters in the determination of ethanol were selected as: applied potential +0.45 V versus Ag/AgCl, flow rate 0.2 mL min{sup -1} in 0.1 M phosphate buffer carrier (pH 7). Different structural designs of the ethanol sensor were tested and linearity obtained was up to 1000 mg L{sup -1} with a maximum R.S.D. of 5

  9. A Simple Green Synthesis of Palladium Nanoparticles with Sargassum Alga and Their Electrocatalytic Activities Towards Hydrogen Peroxide.

    Science.gov (United States)

    Momeni, S; Nabipour, I

    2015-08-01

    This study presents the synthesis of palladium nanoparticles (PdNPs) using the extract derived from the marine alga, Sargassum bovinum, collected from Persian Gulf area. Water-soluble compounds that exist in the marine alga extract were the main cause of the reduction of palladium ions to Pd nanoparticles. The basic properties of PdNPs produced in this method were confirmed by UV-visible spectroscopy, transmission electron microscopy (TEM), X-ray diffraction (XRD), energy-dispersive X-ray (EDX) analysis, and Fourier transform infrared spectroscopy (FTIR). TEM confirmed the monodispersed and octahedral shape of PdNPs within the size ranges from 5 to 10 nm. Catalytic performance of the biosynthetic PdNPs was investigated by electrochemical reduction of hydrogen peroxide (H2O2). PdNP-modified carbon ionic liquid electrode (PdNPs/CILE) was developed as a nonenzymatic sensor for the determination of hydrogen peroxide. Amperometric measurements showed that PdNPs/CILE is a reliable sensor for the detection of hydrogen peroxide in the range of 5.0 μM-15.0 mM with a sensitivity of 284.35 mAmM(-1) cm(-2) and a detection limit of 1.0 μM. Moreover, PdNPs/CILE exhibits a wide linear range, high sensitivity and selectivity, and excellent stability for the detection of H2O2 in aqueous solutions. PMID:26041058

  10. Activation of Wnt/β-catenin signaling by hydrogen peroxide transcriptionally inhibits NaV1.5 expression.

    Science.gov (United States)

    Wang, Ning; Huo, Rong; Cai, Benzhi; Lu, Yan; Ye, Bo; Li, Xiang; Li, Faqian; Xu, Haodong

    2016-07-01

    Oxidants and canonical Wnt/β-catenin signaling have been shown to decrease cardiac Na(+) channel activity by suppressing NaV1.5 expression. Our aims are to determine if hydrogen peroxide (H2O2), one oxidant of reactive oxygen species (ROS), activates Wnt/β-catenin signaling and promotes β-catenin nuclear activity, leading to suppression of NaV1.5 expression and if this suppression requires the interaction of β-catenin with its nuclear partner, TCF4 (also called TCF7L2) to decrease SCN5a promoter activity. The results demonstrated that H2O2 increased β-catenin, but not TCF4 nuclear localization determined by immunofluorescence without affecting total β-catenin protein level. Furthermore, H2O2 exerted a dose- and time-dependent suppressive effect on NaV1.5 expression. RT-PCR and/or Western blot analyses revealed that overexpressing active form of β-catenin or stabilizing β-catenin by GSK-3β inhibitors, LiCl and Bio, suppressed NaV1.5 expression in HL-1 cells. In contrast, destabilization of β-catenin by a constitutively active GSK-3β mutant (S9A) upregulated NaV1.5 expression. Whole-cell recording showed that LiCl significantly inhibited Na(+) channel activity in these cells. Using immunoprecipitation (IP), we showed that β-catenin interacted with TCF4 indicating that β-catenin as a co-transfactor, regulates NaV1.5 expression through TCF4. Analyses of the SCN5a promoter sequences among different species by using VISTA tools indicated that SCN5a promoter harbors TCF4 binding sites. Chromatin IP assays demonstrated that both β-catenin and TCF4 were recruited in the SCN5a promoter, and regulated its activity. Luciferase promoter assays exhibited that β-catenin inhibited the SCN5a promoter activity at a dose-dependent manner and this inhibition required TCF4. Small interfering (Si) RNA targeting β-catenin significantly increased SCN5a promoter activity, leading to enhanced NaV1.5 expression. As expected, β-catenin SiRNA prevents H2O2 suppressive effects

  11. Effect of menadione and hydrogen peroxide on catalase activity in Saccharomyces yeast strains

    OpenAIRE

    Nadejda EFREMOVA; Elena MOLODOI; Agafia USATÎI; Ludmila FULGA; Tamara BORISOVA

    2013-01-01

    It has been studied the possibility of utilization of two important oxidant factors as regulators of catalase activity in Saccharomyces yeasts. In this paper results of the screening of some Saccharomyces yeast strains for potential producers of catalase are presented. Results of the screening for potential catalase producer have revealed that Saccharomyces cerevisiae CNMN-Y-11 strain possesses the highest catalase activity (2900 U/mg protein) compared with other samples. Maximum increase of ...

  12. Influence of Foreign DNA Introduction and Periplasmic Expression of Recombinant Human Interleukin-2 on Hydrogen Peroxide Quantity and Catalase Activity in Escherichia coli

    OpenAIRE

    Lena Mahmoudi Azar; Elnaz Mehdizadeh Aghdam; Farrokh Karimi; Babak Haghshenas; Abolfazl Barzegari; Parichehr Yaghmaei; Mohammad Saeid Hejazi

    2013-01-01

    Purpose: Oxidative stress is generated through imbalance between composing and decomposing of reactive oxygen species (ROS). This kind of stress was rarely discussed in connection with foreign protein production in Escherichia coli. Effect of cytoplasmic recombinant protein expression on Hydrogen peroxide concentration and catalase activity was previously reported. In comparison with cytoplasm, periplasmic space has different oxidative environment. Therefore, in present study we describe t...

  13. Improvement of adventitious root formation in flax using hydrogen peroxide.

    Science.gov (United States)

    Takáč, Tomáš; Obert, Bohuš; Rolčík, Jakub; Šamaj, Jozef

    2016-09-25

    Flax (Linum usitatissimum L.) is an important crop for the production of oil and fiber. In vitro manipulations of flax are used for genetic improvement and breeding while improvements in adventitious root formation are important for biotechnological programs focused on regeneration and vegetative propagation of genetically valuable plant material. Additionally, flax hypocotyl segments possess outstanding morphogenetic capacity, thus providing a useful model for the investigation of flax developmental processes. Here, we investigated the crosstalk between hydrogen peroxide and auxin with respect to reprogramming flax hypocotyl cells for root morphogenetic development. Exogenous auxin induced the robust formation of adventitious roots from flax hypocotyl segments while the addition of hydrogen peroxide further enhanced this process. The levels of endogenous auxin (indole-3-acetic acid; IAA) were positively correlated with increased root formation in response to exogenous auxin (1-Naphthaleneacetic acid; NAA). Histochemical staining of the hypocotyl segments revealed that hydrogen peroxide and peroxidase, but not superoxide, were positively correlated with root formation. Measurements of antioxidant enzyme activities showed that endogenous levels of hydrogen peroxide were controlled by peroxidases during root formation from hypocotyl segments. In conclusion, hydrogen peroxide positively affected flax adventitious root formation by regulating the endogenous auxin levels. Consequently, this agent can be applied to increase flax regeneration capacity for biotechnological purposes such as improved plant rooting. PMID:26921706

  14. The antimicrobial activity of prototype modified honeys that generate reactive oxygen species (ROS) hydrogen peroxide

    OpenAIRE

    Cooke, Jonathan; Dryden, Matthew; Patton, Thomas; Brennan, James; Barrett, John

    2015-01-01

    Background Antimicrobial resistance continues to be a global issue in healthcare organisations. Honey has long been shown to possess wound healing and antimicrobial properties that are dependent on a number of physical and chemical properties of the honey. We tested the antimicrobial activity of a medicinal honey, Surgihoney® (SH) and two prototype modified honeys made by Apis mellifera (honeybee) against Staphylococcus aureus (NCIMB 9518). We also examined the modified honey prototypes for t...

  15. Cervicovaginal fluid and semen block the microbicidal activity of hydrogen peroxide produced by vaginal lactobacilli

    Directory of Open Access Journals (Sweden)

    Moench Thomas R

    2010-05-01

    Full Text Available Abstract Background H2O2 produced by vaginal lactobacilli is believed to protect against infection, and H2O2-producing lactobacilli inactivate pathogens in vitro in protein-free salt solution. However, cervicovaginal fluid (CVF and semen have significant H2O2-blocking activity. Methods We measured the H2O2 concentration of CVF and the H2O2-blocking activity of CVF and semen using fluorescence and in vitro bacterial-exposure experiments. Results The mean H2O2 measured in fully aerobic CVF was 23 ± 5 μM; however, 50 μM H2O2 in salt solution showed no in vitro inactivation of HSV-2, Neisseria gonorrhoeae, Hemophilus ducreyii, or any of six BV-associated bacteria. CVF reduced 1 mM added H2O2 to an undetectable level, while semen reduced 10 mM added H2O2 to undetectable. Moreover, the addition of just 1% CVF supernatant abolished in vitro pathogen-inactivation by H2O2-producing lactobacilli. Conclusions Given the H2O2-blocking activity of CVF and semen, it is implausible that H2O2-production by vaginal lactobacilli is a significant mechanism of protection in vivo.

  16. Bactericidal and cytotoxic effects of hypothiocyanite-hydrogen peroxide mixtures.

    OpenAIRE

    Carlsson, J.; Edlund, M B; Hänström, L.

    1984-01-01

    Lactoperoxidase catalyzes the oxidation of thiocyanate by hydrogen peroxide into hypothiocyanite, a reaction which can protect bacterial and mammalian cells from killing by hydrogen peroxide. The present study demonstrates, however, that lactoperoxidase in the presence of thiocyanate can actually potentiate the bactericidal and cytotoxic effects of hydrogen peroxide under specific conditions, such as when hydrogen peroxide is present in the reaction mixtures in excess of thiocyanate. The toxi...

  17. Redox Modulation of PTEN Phosphatase Activity by Hydrogen Peroxide and Bisperoxidovanadium Complexes.

    Science.gov (United States)

    Lee, Chang-Uk; Hahne, Gernot; Hanske, Jonas; Bange, Tanja; Bier, David; Rademacher, Christoph; Hennig, Sven; Grossmann, Tom N

    2015-11-01

    PTEN is a dual-specificity protein tyrosine phosphatase. As one of the central tumor suppressors, a thorough regulation of its activity is essential for proper cellular homeostasis. The precise implications of PTEN inhibition by reactive oxygen species (e.g. H2 O2 ) and the subsequent structural consequences remain elusive. To study the effects of PTEN inhibition, bisperoxidovanadium (bpV) complexes serve as important tools with the potential for the treatment of nerve injury or cardiac ischemia. However, their mode of action is unknown, hampering further optimization and preventing therapeutic applications. Based on protein crystallography, mass spectrometry, and NMR spectroscopy, we elucidate the molecular basis of PTEN inhibition by H2O2 and bpV complexes. We show that both molecules inhibit PTEN via oxidative mechanisms resulting in the formation of the same intramolecular disulfide, therefore enabling the reactivation of PTEN under reductive conditions. PMID:26418532

  18. Optimized enzymatic colorimetric assay for determination of hydrogen peroxide (H2O2) scavenging activity of plant extracts

    Science.gov (United States)

    Fernando, Chamira Dilanka; Soysa, Preethi

    2015-01-01

    The classical method to determine hydrogen peroxide (H2O2) scavenging activity of plant extracts is evaluated by measuring the disappearance of H2O2 at a wavelength of 230 nm. Since this method suffers from the interference of phenolics having strong absorption in the UV region, a simple and rapid colorimetric assay was developed where plant extracts are introduced to H2O2, phenol and 4-aminoantipyrine reaction system in the presence of horseradish peroxidase (HRP). This reaction yields a quinoneimine chromogen which can be measured at 504 nm. Decrease in the colour intensity reflects the H2O2 scavenged by the plant material. • Optimum conditions determined for this assay were 30 min reaction time, 37 °C, pH 7, enzyme concentration of 1 U/ml and H2O2 concentration of 0.7 mM. The limit of detection (LOD) and limit of quantitation (LOQ) were 136 μM and 411 μM, respectively. • Half maximal effective concentration required to scavenge 50% of H2O2 in the system (EC50 value) calculated for several plant extracts and standard antioxidants resulted in coefficient of variance (CV%) of the EC50 values less than 3.0% and correlation coefficient values (R2) > 0.95 for all dose response curves obtained. • This method is convenient and very precise which is suitable for the rapid quantification of H2O2 scavenging ability of standard antioxidants and natural antioxidants present in plant extracts. PMID:26285798

  19. Impact of hydrogen peroxide as a soil amendment on nasturtiums

    Science.gov (United States)

    Hydrogen peroxide, H2O2, is a highly reactive oxidizing agent naturally occurring in plants and animals. Plants produce hydrogen peroxide to destroy either their infected plant cells or the pathogens within their cells. Hydrogen peroxide also acts as a stress signal to plants. It is approved for c...

  20. Ozone inhibits endothelial cell cyclooxygenase activity through formation of hydrogen peroxide

    Energy Technology Data Exchange (ETDEWEB)

    Madden, M.C.; Eling, T.E.; Friedman, M.

    1987-09-01

    We have previously demonstrated that a 2H exposure of cultured pulmonary endothelial cells to ozone (0.0-1.0 ppm) in-vitro resulted in a concentration-dependent reduction of endothelial prostacyclin production (90% decrease at the 1.0 ppm level). Ozone-exposed endothelial cells, incubated with 20 uM arachidonate, also demonstrated a significant inhibition of prostacyclin synthesis. To further examine the mechanisms of the inhibition of prostacyclin synthesis, bovine pulmonary endothelial cells were exposed to 1.0 ppm ozone for 2H. A significant decrease in prostacyclin synthesis was found within 5 min of exposure (77 +/- 36% of air-exposed control values, p less than 0.05). Endothelial prostacyclin synthesis returned to baseline levels by 12H after ozone exposure, a time point which was similar to the recovery time of unexposed endothelium treated with 0.5 uM acetylsalicylic acid. Incubation of endothelial cells, previously exposed to 1.0 ppm ozone for 2 hours, with 4 uM PGH2 resulted in restoration of essentially normal prostacyclin synthesis. When endothelial cells were co-incubated with catalase (5 U/ml) during ozone exposure, no inhibition of prostacyclin synthesis was observed. Co-incubation with either heat-inactivated catalase or superoxide dismutase (10 U/ml) did not affect the ozone-induced inhibition of prostacyclin synthesis. These data suggest that H/sub 2/O/sub 2/ is a major toxic species produced in endothelial cells during ozone exposure and responsible for the inhibition of endothelial cyclooxygenase activity.

  1. Selective Electrochemical Generation of Hydrogen Peroxide from Water Oxidation.

    Science.gov (United States)

    Viswanathan, Venkatasubramanian; Hansen, Heine A; Nørskov, Jens K

    2015-11-01

    Water is a life-giving source, fundamental to human existence, yet over a billion people lack access to clean drinking water. The present techniques for water treatment such as piped, treated water rely on time and resource intensive centralized solutions. In this work, we propose a decentralized device concept that can utilize sunlight to split water into hydrogen and hydrogen peroxide. The hydrogen peroxide can oxidize organics while the hydrogen bubbles out. In enabling this device, we require an electrocatalyst that can oxidize water while suppressing the thermodynamically favored oxygen evolution and form hydrogen peroxide. Using density functional theory calculations, we show that the free energy of adsorbed OH* can be used to determine selectivity trends between the 2e(-) water oxidation to H2O2 and the 4e(-) oxidation to O2. We show that materials which bind oxygen intermediates sufficiently weakly, such as SnO2, can activate hydrogen peroxide evolution. We present a rational design principle for the selectivity in electrochemical water oxidation and identify new material candidates that could perform H2O2 evolution selectively.

  2. Selective electrochemical generation of hydrogen peroxide from water oxidation

    CERN Document Server

    Viswanathan, Venkatasubramanian; Nørskov, Jens K

    2015-01-01

    Water is a life-giving source, fundamental to human existence, yet, over a billion people lack access to clean drinking water. Present techniques for water treatment such as piped, treated water rely on time and resource intensive centralized solutions. In this work, we propose a decentralized device concept that can utilize sunlight to split water into hydrogen and hydrogen peroxide. The hydrogen peroxide can oxidize organics while the hydrogen bubbles out. In enabling this device, we require an electrocatalyst that can oxidize water while suppressing the thermodynamically favored oxygen evolution and form hydrogen peroxide. Using density functional theory calculations, we show that the free energy of adsorbed OH$^*$ can be used as a descriptor to screen for selectivity trends between the 2e$^-$ water oxidation to H$_2$O$_2$ and the 4e$^-$ oxidation to O$_2$. We show that materials that bind oxygen intermediates sufficiently weakly, such as SnO$_2$, can activate hydrogen peroxide evolution. We present a rati...

  3. Experimental investigation of hydrogen peroxide RF plasmas

    Science.gov (United States)

    Barni, R.; Decina, A.; Zanini, S.; D'Orazio, A.; Riccardi, C.

    2016-04-01

    This work reports a detailed experimental study of the plasma properties in low pressure RF discharges in hydrogen peroxide and a comparison with argon under the same operating conditions. H2O2 plasmas have been proposed for sterilization purposes. Electrical properties of the discharge were shown to be similar, as for the RF and DC voltages of the driving electrode. Bulk plasma volume remains stable, concentrated in an almost cylindrical region between the two facing electrodes. It was found that the electron temperature is almost uniform across the plasma and independent of the power level. This is higher than in argon discharges: T e  =  4.6  ±  0.9 eV versus T e  =  3.3  ±  1.1 eV. The plasma density increases almost linearly with the power level and a substantial negative ion component has been ruled out in hydrogen peroxide. Dissociation in the plasma gas phase was revealed by atomic hydrogen and hydroxyl radical emission in the discharge spectra. Emission from hydroxyl and atomic oxygen demonstrates that oxidizing radicals are produced by hydrogen peroxide discharges, revealing its usefulness for plasma processing other than sterilization, for instance to increase polymer film surface energy. On the other hand, argon could be considered as a candidate for the sterilization purposes due to the intense production of UV radiation.

  4. Hydrogen peroxide mediates higher order chromatin degradation.

    Science.gov (United States)

    Bai, H; Konat, G W

    2003-01-01

    Although a large body of evidence supports a causative link between oxidative stress and neurodegeneration, the mechanisms are still elusive. We have recently demonstrated that hydrogen peroxide (H(2)O(2)), the major mediator of oxidative stress triggers higher order chromatin degradation (HOCD), i.e. excision of chromatin loops at the matrix attachment regions (MARs). The present study was designed to determine the specificity of H(2)O(2) in respect to HOCD induction. Rat glioma C6 cells were exposed to H(2)O(2) and other oxidants, and the fragmentation of genomic DNA was assessed by field inversion gel electrophoresis (FIGE). S1 digestion before FIGE was used to detect single strand fragmentation. The exposure of C6 cells to H(2)O(2) induced a rapid and extensive HOCD. Thus, within 30 min, total chromatin was single strandedly digested into 50 kb fragments. Evident HOCD was elicited by H(2)O(2) at concentrations as low as 5 micro M. HOCD was mostly reversible during 4-8h following the removal of H(2)O(2) from the medium indicating an efficient relegation of the chromatin fragments. No HOCD was induced by H(2)O(2) in isolated nuclei indicating that HOCD-endonuclease is activated indirectly by cytoplasmic signal pathways triggered by H(2)O(2). The exposure of cells to a synthetic peroxide, i.e. tert-butyrylhydroperoxide (tBH) also induced HOCD, but to a lesser extent than H(2)O(2). Contrary to the peroxides, the exposure of cells to equitoxic concentration of hypochlorite and spermine NONOate, a nitric oxide generator, failed to induce rapid HOCD. These results indicate that rapid HOCD is not a result of oxidative stress per se, but is rather triggered by signaling cascades initiated specifically by H(2)O(2). Furthermore, the rapid and extensive HOCD was observed in several rat and human cell lines challenged with H(2)O(2), indicating that the process is not restricted to glial cells, but rather represents a general response of cells to H(2)O(2). PMID:12421592

  5. Infusing sodium bicarbonate suppresses hydrogen peroxide accumulation and superoxide dismutase activity in hypoxic-reoxygenated newborn piglets.

    Directory of Open Access Journals (Sweden)

    Jiang-Qin Liu

    Full Text Available BACKGROUND: The effectiveness of sodium bicarbonate (SB has recently been questioned although it is often used to correct metabolic acidosis of neonates. The aim of the present study was to examine its effect on hemodynamic changes and hydrogen peroxide (H(2O(2 generation in the resuscitation of hypoxic newborn animals with severe acidosis. METHODS: Newborn piglets were block-randomized into a sham-operated control group without hypoxia (n = 6 and two hypoxia-reoxygenation groups (2 h normocapnic alveolar hypoxia followed by 4 h room-air reoxygenation, n = 8/group. At 10 min after reoxygenation, piglets were given either i.v. SB (2 mEq/kg, or saline (hypoxia-reoxygenation controls in a blinded, randomized fashion. Hemodynamic data and blood gas were collected at specific time points and cerebral cortical H(2O(2 production was continuously monitored throughout experimental period. Plasma superoxide dismutase and catalase and brain tissue glutathione, superoxide dismutase, catalase, nitrotyrosine and lactate levels were assayed. RESULTS: Two hours of normocapnic alveolar hypoxia caused cardiogenic shock with metabolic acidosis (PH: 6.99 ± 0.07, HCO(3(-: 8.5 ± 1.6 mmol/L. Upon resuscitation, systemic hemodynamics immediately recovered and then gradually deteriorated with normalization of acid-base imbalance over 4 h of reoxygenation. SB administration significantly enhanced the recovery of both pH and HCO(3- recovery within the first hour of reoxygenation but did not cause any significant effect in the acid-base at 4 h of reoxygenation and the temporal hemodynamic changes. SB administration significantly suppressed the increase in H(2O(2 accumulation in the brain with inhibition of superoxide dismutase, but not catalase, activity during hypoxia-reoxygenation as compared to those of saline-treated controls. CONCLUSIONS: Despite enhancing the normalization of acid-base imbalance, SB administration during resuscitation did not provide any beneficial

  6. Co-operative inhibitory effects of hydrogen peroxide and iodine against bacterial and yeast species

    OpenAIRE

    Zubko, Elena I; Zubko, Mikhajlo K

    2013-01-01

    Background Hydrogen peroxide and iodine are powerful antimicrobials widely used as antiseptics and disinfectants. Their antimicrobial properties are known to be enhanced by combining them with other compounds. We studied co-operative inhibitory activities (synergism, additive effects and modes of growth inhibition) of hydrogen peroxide and iodine used concurrently against 3 bacterial and 16 yeast species. Results Synergistic or additive inhibitory effects were shown for hydrogen peroxide and ...

  7. Hydrogen Peroxide Propulsion for Smaller Satellites

    OpenAIRE

    Whitehead, John

    1998-01-01

    As satellite designs shrink, providing maneuvering and control capability falls outside the realm of available propulsion technology. While cold gas has been used on the smallest satellites, hydrogen peroxide propellant is suggested as the next step in performance and cost before hydrazine. Minimal toxicity and a small scale enable bench top propellant preparation and development testing. Progress toward low-cost thrusters and self-pressurizing tank systems is described.

  8. Quantifying intracellular hydrogen peroxide perturbations in terms of concentration

    Directory of Open Access Journals (Sweden)

    Beijing K. Huang

    2014-01-01

    Full Text Available Molecular level, mechanistic understanding of the roles of reactive oxygen species (ROS in a variety of pathological conditions is hindered by the difficulties associated with determining the concentration of various ROS species. Here, we present an approach that converts fold-change in the signal from an intracellular sensor of hydrogen peroxide into changes in absolute concentration. The method uses extracellular additions of peroxide and an improved biochemical measurement of the gradient between extracellular and intracellular peroxide concentrations to calibrate the intracellular sensor. By measuring peroxiredoxin activity, we found that this gradient is 650-fold rather than the 7–10-fold that is widely cited. The resulting calibration is important for understanding the mass-action kinetics of complex networks of redox reactions, and it enables meaningful characterization and comparison of outputs from endogenous peroxide generating tools and therapeutics across studies.

  9. Hydrogen Peroxide Stimulates the Ca2+-activated Big-Conductance K Channels (BK) Through cGMP Signaling Pathway in Cultured Human Endothelial Cells

    OpenAIRE

    Dong, De-Li; Yue, Peng; Yang, Bao-Feng; Wang, Wen-Hui

    2008-01-01

    We used the whole cell patch-clamp technique to examine the effect of hydrogen peroxide (H2O2) on the Ca2+-activated BK channels in human endothelial cells. We confirmed the previous finding that a 200 pS BK channel activity was detected when the cell membrane potential was clamped at 50 mV. Application of H2O2 or adding glucose oxidase (GO) stimulated BK channels. The stimulatory effect of H2O2 and GO was absent in cells treated with ebselen, a scavenger of reactive oxygen species (ROS). To ...

  10. Effects of resveratrol on hydrogen peroxide-induced oxidative stress in embryonic neural stem cells

    Institute of Scientific and Technical Information of China (English)

    Sibel Konyalioglu; Guliz Armagan; Ayfer Yalcin; Cigdem Atalayin; Taner Dagci

    2013-01-01

    Resveratrol, a natural phenolic compound, has been shown to prevent cardiovascular diseases and cancer and exhibit neuroprotective effects. In this study, we examined the neuroprotective and antioxidant effects of resveratrol against hydrogen peroxide in embryonic neural stem cells. Hydrogen peroxide treatment alone increased catalase and glutathione peroxidase activities but did not change superoxide dismutase levels compared with hydrogen peroxide + resveratrol treatment. Nitric oxide synthase activity and concomitant nitric oxide levels increased in response to hydrogen peroxide treatment. Conversely, resveratrol treatment decreased nitric oxide synthase activity and nitric oxide levels. Resveratrol also attenuated hydrogen peroxide-induced nuclear or mitochondrial DNA damage. We propose that resveratrol may be a promising agent for protecting embryonic neural stem cells because of its potential to decrease oxidative stress by inducing higher activity of antioxidant enzymes, decreasing nitric oxide production and nitric oxide synthase activity, and alleviating both nuclear and mitochondrial DNA damage.

  11. Hydrogen sulfide prevents hydrogen peroxide-induced activation of epithelial sodium channel through a PTEN/PI(3,4,5P3 dependent pathway.

    Directory of Open Access Journals (Sweden)

    Jianing Zhang

    Full Text Available Sodium reabsorption through the epithelial sodium channel (ENaC at the distal segment of the kidney plays an important role in salt-sensitive hypertension. We reported previously that hydrogen peroxide (H2O2 stimulates ENaC in A6 distal nephron cells via elevation of phosphatidylinositol 3,4,5-trisphosphate (PI(3,4,5P3 in the apical membrane. Here we report that H2S can antagonize H2O2-induced activation of ENaC in A6 cells. Our cell-attached patch-clamp data show that ENaC open probability (PO was significantly increased by exogenous H2O2, which is consistent with our previous finding. The aberrant activation of ENaC induced by exogenous H2O2 was completely abolished by H2S (0.1 mM NaHS. Pre-treatment of A6 cells with H2S slightly decreased ENaC P(O; however, in these cells H2O2 failed to elevate ENaC PO . Confocal microscopy data show that application of exogenous H2O2 to A6 cells significantly increased intracellular reactive oxygen species (ROS level and induced accumulation of PI(3,4,5P3 in the apical compartment of the cell membrane. These effects of exogenous H2O2 on intracellular ROS levels and on apical PI(3,4,5P3 levels were almost completely abolished by treatment of A6 cells with H2S. In addition, H2S significantly inhibited H2O2-induced oxidative inactivation of the tumor suppressor phosphatase and tensin homolog (PTEN which is a negative regulator of PI(3,4,5P3. Moreover, BPV(pic, a specific inhibitor of PTEN, elevated PI(3,4,5P3 and ENaC activity in a manner similar to that of H2O2 in A6 cells. Our data show, for the first time, that H2S prevents H2O2-induced activation of ENaC through a PTEN-PI(3,4,5P3 dependent pathway.

  12. Hydrogen peroxide potentiates organophosphate toxicosis in chicks

    Directory of Open Access Journals (Sweden)

    Banan K. Al-Baggou

    2011-11-01

    Full Text Available Objective: The purpose of the present study was to examine the effect of hydrogen peroxide(H2O2 on the acute toxicity of organophosphate insecticides dichlorvos and diazinon and their inhibitoryactions on plasma, brain and liver cholinesterase activities. Material and Methods: H2O2 was given indrinking water (0.5% v/v for 2 weeks in unsexed day old chicks, a regimen known to induce oxidativestress in this species. A control group received drinking tap water. All experiments were conducted onthe chicks at the age of 15 days after exposure to H2O2. The acute (24 h oral LD50 values of dichlorvosand diazinon in the insecticidal preparations as determined by the up-and-down method in the controlchicks were 9.4 and 15.6 mg/kg, respectively. Results: The poisoned chicks manifested signs ofcholinergic toxicosis within one hour after the dosing including salivation, lacrimation, gasping, frequentdefecation, drooping of wings, tremors, convulsions and recumbency. The acute (24 h oral LD50 valuesof dichlorvos and diazinon in chicks provided with H2O2 were reduced to 3.5 and 6.5 mg/kg, by 63 and58%, respectively when compared to respective control LD50 values. The intoxicated chicks also showedcholinergic signs of toxicosis as described above. Plasma, brain and liver cholinesterase activities of thechicks exposed to H2O2 were significantly lower than their respective control (H2O values by 25, 28 and27%, respectively. Oral dosing of chicks with dichlorvos at 3 mg/kg significantly inhibited cholinesteraseactivities in the plasma, brain and liver of both control (42-67% and H2O2-treated (15-59% chicks.Diazinon at 5 mg/kg, orally also inhibited cholinesterase activities in the plasma, brain and liver of bothcontrol (36-66% and H2O2-treated (15-30% chicks. In the H2O2 groups, dichlorvos inhibition of livercholinesterase activity and diazinon inhibition of liver and brain cholinesterase activities weresignificantly lesser than those of the respective values of

  13. Estudio cinético de la descomposición catalizada de peróxido de hidrógeno sobre carbón activado Kinetic study of the catalyzed decomposition of hydrogen peroxide on activated carbon

    Directory of Open Access Journals (Sweden)

    Elihu Paternina

    2009-01-01

    Full Text Available The kinetic study of decomposition of hydrogen peroxide catalyzed by activated carbon was carried out. The effect of concentrations of reactants and temperature were experimentally studied. Kinetic data were evaluated using differential method of initial rates of reaction. When a typical kinetic law for reactions in homogeneous phase is used, first order of reaction is obtained for hydrogen peroxide and activated carbon, and activation energy of 27 kJ mol-1 for the reaction was estimated. Experimentally was observed that surface of activated carbon is chemically modified during decomposition of hydrogen peroxide, based on this result a scheme of reaction was proposed and evaluated. Experimental data fits very well to a Langmuir- Hinshelwood kinetic model and activation energy of 40 kJ mol-1 was estimated for reaction in heterogeneous phase.

  14. Influence of Foreign DNA Introduction and Periplasmic Expression of Recombinant Human Interleukin-2 on Hydrogen Peroxide Quantity and Catalase Activity in Escherichia coli

    Directory of Open Access Journals (Sweden)

    Lena Mahmoudi Azar

    2013-08-01

    Full Text Available Purpose: Oxidative stress is generated through imbalance between composing and decomposing of reactive oxygen species (ROS. This kind of stress was rarely discussed in connection with foreign protein production in Escherichia coli. Effect of cytoplasmic recombinant protein expression on Hydrogen peroxide concentration and catalase activity was previously reported. In comparison with cytoplasm, periplasmic space has different oxidative environment. Therefore, in present study we describe the effect of periplasmic expression of recombinant human interleukin-2 (hIL-2 on H2O2 concentration and catalase activity in Escherichia coli and their correlation with cell growth. Methods: Having constructed pET2hIL2 vector, periplasmic expression of hIL-2 was confirmed. Then, H2O2 concentration and catalase activity were determined at various ODs. Wild type and empty vector transformed cells were used as negative controls. Results: It was shown that H2O2 concentration in hIL-2 expressing cells was significantly higher than its concentration in wild type and empty vector transformed cells. Catalase activity and growth rate reduced significantly in hIL-2 expressing cells compared to empty vector transformed and wild type cells. Variation of H2O2 concentration and catalase activity is intensive in periplasmic hIL-2 expressing cells than empty vector containing cells. Correlation between H2O2 concentration elevation and catalase activity reduction with cell growth depletion are also demonstrated. Conclusion: Periplasmic expression of recombinant hIL-2 elevates the host cell’s hydrogen peroxide concentration possibly due to reduced catalase activity which has consequent suppressive effect on growth rate.

  15. Demonstration of the Catalytic Decomposition of Hydrogen Peroxide.

    Science.gov (United States)

    Conklin, Alfred R. Jr.; Kessinger, Angela

    1996-01-01

    Describes a demonstration known as Elephant's Toothpaste in which the decomposition of hydrogen peroxide is catalyzed by iodide. Oxygen is released and soap bubbles are produced. The foam produced is measured, and results show a good relationship between the amount of foam and the concentration of the hydrogen peroxide. (DDR)

  16. A hydrogen peroxide sensor for exhaled breath measurement

    NARCIS (Netherlands)

    Anh, Dam Thi Van; Olthuis, W.; Bergveld, P.

    2005-01-01

    An increase in hydrogen peroxide concentration in exhaled breath (EB) of patients, who suffer from some diseases related to the lung function, has been observed and considered as a reliable indicator of lung diseases. In the EB of these patients, hydrogen peroxide is present in the vapour phase toge

  17. A hydrogen peroxide sensor for exhaled breath measurement

    NARCIS (Netherlands)

    Anh, Dam T.V.; Olthuis, W.; Bergveld, P.; Berg, van den A.

    2004-01-01

    An increase in produced hydrogen peroxide concentration in exhaled breath (EB) of patients, who suffer from some diseases related to lung function, has been observed and considered as a reliable indicator of lung diseases. In the EB of these patients, hydrogen peroxide is present in the vapour phase

  18. Hydrogen Peroxide Storage in Small Sealed Tanks

    Energy Technology Data Exchange (ETDEWEB)

    Whitehead, J.

    1999-10-20

    Unstabilized hydrogen peroxide of 85% concentration has been prepared in laboratory quantities for testing material compatibility and long term storage on a small scale. Vessels made of candidate tank and liner materials ranged in volume from 1 cc to 2540 cc. Numerous metals and plastics were tried at the smallest scales, while promising ones were used to fabricate larger vessels and liners. An aluminum alloy (6061-T6) performed poorly, including increasing homogeneous decay due to alloying elements entering solution. The decay rate in this high strength aluminum was greatly reduced by anodizing. Better results were obtained with polymers, particularly polyvinylidene fluoride. Data reported herein include ullage pressures as a function of time with changing decay rates, and contamination analysis results.

  19. Detection of hydrogen peroxide by lactoperoxidase-mediated dityrosine formation.

    Science.gov (United States)

    Donkó, Agnes; Orient, Anna; Szabó, Pál T; Németh, Gábor; Vántus, Tibor; Kéri, György; Orfi, László; Hunyady, László; Buday, László; Geiszt, Miklós

    2009-05-01

    The aim of this work was to study the dityrosine-forming activity of lactoperoxidase (LPO) and its potential application for measuring hydrogen peroxide (H2O2). It was observed that LPO was able to form dityrosine at low H2O2 concentrations. Since dityrosine concentration could be measured in a simple fluorimetric reaction, this activity of the enzyme was utilized for the measurement of H2O2 production in different systems. These experiments successfully measured the activity of NADPH oxidase 4 (Nox4) by this method. It was concluded that LPO-mediated dityrosine formation offers a simple way for H2O2 measurement.

  20. Protein-directed in situ synthesis of platinum nanoparticles with superior peroxidase-like activity, and their use for photometric determination of hydrogen peroxide

    International Nuclear Information System (INIS)

    Platinum nanoparticles (Pt-NPs) with sizes in the range from 10 to 30 nm were synthesized using protein-directed one-pot reduction. The model globular protein bovine serum albumin (BSA) was exploited as the template, and the resulting BSA/Pt-NPs were studied by transmission electron microscopy, energy dispersive X-ray spectroscopy, and resonance Rayleigh scattering spectroscopy. The modified nanoparticles display a peroxidase-like activity that was exploited in a rapid method for the colorimetric determination of hydrogen peroxide which can be detected in the 50 μM to 3 mM concentration range. The limit of detection is 7.9 μM, and the lowest concentration that can be visually detected is 200 μM. (author)

  1. INVOLVEMENT OF CATALASE IN SACCHAROMYCES CEREVISIAE HORMETIC RESPONSE TO HYDROGEN PEROXIDE

    Directory of Open Access Journals (Sweden)

    Ruslana Vasylkovska

    2015-05-01

    Full Text Available In this study, we investigated the relationship between catalase activity and H2O2-induced hormetic response in budding yeast S. cerevisiae. In general, our data suggest that: (i hydrogen peroxide induces hormesis in a concentration- and time-dependent manner; and (ii the effect of hydrogen peroxide on yeast colony growth positively correlates with the activity of catalase that suggests the enzyme involvement in overall H2O2-induced stress response and hormetic response in yeast.

  2. INVOLVEMENT OF CATALASE IN SACCHAROMYCES CEREVISIAE HORMETIC RESPONSE TO HYDROGEN PEROXIDE

    OpenAIRE

    Ruslana Vasylkovska; Nadia Burdylyuk; Halyna Semchyshyn

    2015-01-01

    In this study, we investigated the relationship between catalase activity and H2O2-induced hormetic response in budding yeast S. cerevisiae. In general, our data suggest that: (i) hydrogen peroxide induces hormesis in a concentration- and time-dependent manner; and (ii) the effect of hydrogen peroxide on yeast colony growth positively correlates with the activity of catalase that suggests the enzyme involvement in overall H2O2-induced stress response and hormetic response in yeast.

  3. THE EFFECT OF TRANSITION METAL IONS-MANGANESE ON HYDROGEN PEROXIDE BLEACHING

    Institute of Scientific and Technical Information of China (English)

    ShuhuiYang; YumengZhao; BaokuWen; YonghaoNi

    2004-01-01

    In this investigation, the catalytic activities of Mn(II),Mn(III) and Mn(IV) towards decomposing hydrogenperoxide were compared. Among Mn (II), Mn (III)and Mn (IV), Mn (II) is not catalytically active indecomposing hydrogen peroxide. However, both Mn(113) and Mn (IV) are, and Mn (III) has a strongereffect than Mn(IV).In addition, we also studied the practical methods todecrease the Mn-induced decomposition of hydrogenperoxide. The results showed that sodium silicate andmagnesium sulfite in combination can effectivelydecrease the decomposition of hydrogen peroxide.The optimum dosage of sodium silicate was about0.5% (on solution). Adding chelants such as DTPAor EDTA simultaneously with stabilizers candecrease hydrogen peroxide decomposition. For Mn(IV), the EDTA is more effective than DTPA.Adding sodium thiosulfate simultaneously withmagnesium sulfate, sodium silicate and DTPA toalkaline peroxide solution can result in more residualhydrogen peroxide, and a higher pulp brightness.

  4. Evaluation of anti-apoptotic activity of different dietary antioxidants in renal cell carcinoma against hydrogen peroxide

    Institute of Scientific and Technical Information of China (English)

    Garg; Neeraj; K; Mangal; Sharad; Sahu; Tejram; Mehta; Abhinav; Vyas; Suresh; P; Tyagi; Rajeev; K

    2011-01-01

    Objective:To evaluate the anti-apoptotic and radical scavenging activities of dietary phenolics, namely ascorbic acid,a-tocopherol acetate,citric acid,salicylic acid,and estimate H2O2induced apoptosis in renal cell carcinoma cells.Methods:The intracellular antioxidant potency of antioxidants was investigated.H2O-2-induced apoptosis in RCC-26 was assayed with the following parameters:cell viability(%apoptosis),nucleosomal damage and DNA fragmentation, bcl-2 levels and flow cytometery analysis(ROS production evaluation).Results:Ine anticancer properties of antioxidants such as ascorbic acid,a- tocopherol acetate,citric acid,salicylic acid with perdurable responses were investigated.It was observed that these antioxidants had protective effect(anti-apoptotic activity) against hydrogen peroxide(H2O2) in renal cell carcinoma(RCC-26) cell line.Conclusions:This study reveals and proves the anticancer properties.However,in cancer cell lines anti-apoptotic activity can indirectly reflect the cancer promoter activity through radicals scavenging,and significantly protect nucleus and bcl-2.

  5. Antioxidant activity of honey samples from Trás-os-Montes and inhibitory effect of hydrogen peroxide on pathogenic yeast growth

    OpenAIRE

    Pereira, Ana Paula; Ferreira, Isabel C.F.R.; Leticia M. Estevinho

    2007-01-01

    Honey has been used since ancient times in the treatment of respiratory infections and to heal wounds. These effects are related to its physical and chemical properties. The major antibacterial factor in honey is hydrogen peroxide, which is produced by glucose oxidase originating from hypopharyngeal glands of honey bees, and by catalase, which a originates from pollen

  6. Anti-apoptotic Activity of Ginsenoside Rb1 in Hydrogen Peroxide-treated Chondrocytes: Stabilization of Mitochondria and the Inhibition of Caspase-3.

    Science.gov (United States)

    Na, Ji-Young; Kim, Sokho; Song, Kibbeum; Lim, Kyu-Hee; Shin, Gee-Wook; Kim, Jong-Hoon; Kim, Bumseok; Kwon, Young-Bae; Kwon, Jungkee

    2012-07-01

    Chondrocyte apoptosis has been recognized as an important factor in the pathogenesis of osteoarthritis (OA). Hydrogen peroxide (H2O2), which produces reactive oxygen species, reportedly induces apoptosis in chondrocytes. The ginsenoside Rb1 (GRb1) is the principal component in ginseng and has been shown to have a variety of biological activities, such as anti-arthritis, anti-inflammation, and anti-tumor activities. In this study, we evaluated the effects of G-Rb1 on the mitochondrial permeability transition (MPT) and caspase-3 activity of chondrocyte apoptosis induced by H2O2. Cultured rat articular chondrocytes were exposed to H2O2 with or without G-Rb1 and assessed for viability, MPT, Bcl-xL/Bax expression, caspase-3 activity, and apoptosis. The co-treatment with G-Rb1 showed an inhibition of MPT, caspase-3 activity, and cell death. Additionally, the levels of the apoptotic protein Bax were significantly lower and the levels of the anti-apoptotic protein Bcl-xL were higher compared with H2O2 treatment alone. The results of this study demonstrate that G-Rb1 protects chondrocytes against H2O2-induced apoptosis, at least in part via the inhibition of MPT and caspase-3 activity. These results demonstrate that G-Rb1 is a potentially useful drug for the treatment of OA patients. PMID:23717124

  7. Ultraviolet (UV and Hydrogen Peroxide Activate Ceramide-ER Stress-AMPK Signaling Axis to Promote Retinal Pigment Epithelium (RPE Cell Apoptosis

    Directory of Open Access Journals (Sweden)

    Jin Yao

    2013-05-01

    Full Text Available Ultraviolet (UV radiation and reactive oxygen species (ROS impair the physiological functions of retinal pigment epithelium (RPE cells by inducing cell apoptosis, which is the main cause of age-related macular degeneration (AMD. The mechanism by which UV/ROS induces RPE cell death is not fully addressed. Here, we observed the activation of a ceramide-endoplasmic reticulum (ER stress-AMP activated protein kinase (AMPK signaling axis in UV and hydrogen peroxide (H2O2-treated RPE cells. UV and H2O2 induced an early ceramide production, profound ER stress and AMPK activation. Pharmacological inhibitors against ER stress (salubrinal, ceramide production (fumonisin B1 and AMPK activation (compound C suppressed UV- and H2O2-induced RPE cell apoptosis. Conversely, cell permeable short-chain C6 ceramide and AMPK activator AICAR (5-amino-1-β-D-ribofuranosyl-imidazole-4-carboxamide mimicked UV and H2O2’s effects and promoted RPE cell apoptosis. Together, these results suggest that UV/H2O2 activates the ceramide-ER stress-AMPK signaling axis to promote RPE cell apoptosis.

  8. THE EFFECT OF TRANSITION METAL IONS-MANGANESE ON HYDROGEN PEROXIDE BLEACHING

    Institute of Scientific and Technical Information of China (English)

    Shuhui Yang; Yumeng Zhao; Baoku Wen; Yonghao Ni

    2004-01-01

    In this investigation, the catalytic activities of Mn(Ⅱ),Mn(Ⅲ) and Mn(Ⅳ) towards decomposing hydrogen peroxide were compared. Among Mn (Ⅱ), Mn (Ⅲ)and Mn (Ⅳ), Mn (Ⅱ) is not catalytically active in decomposing hydrogen peroxide. However, both Mn (Ⅲ) and Mn (Ⅳ) are, and Mn (Ⅲ) has a stronger effect than Mn(Ⅳ).In addition, we also studied the practical methods to decrease the Mn-induced decomposition of hydrogen peroxide. The results showed that sodium silicate and magnesium sulfite in combination can effectively decrease the decomposition of hydrogen peroxide.The optimum dosage of sodium silicate was about 0.5% (on solution). Adding chelants such as DTPA or EDTA simultaneously with stabilizers can decrease hydrogen peroxide decomposition. For Mn (Ⅳ), the EDTA is more effective than DTPA.Adding sodium thiosulfate simultaneously with magnesium sulfate, sodium silicate and DTPA to alkaline peroxide solution can result in more residual hydrogen peroxide, and a higher pulp brightness.

  9. Selective Electrochemical Generation of Hydrogen Peroxide from Water Oxidation

    DEFF Research Database (Denmark)

    Viswanathan, Venkatasubramanian; Hansen, Heine Anton; Nørskov, Jens K.

    2015-01-01

    Water is a life-giving source, fundamental to human existence, yet over a billion people lack access to clean drinking water. The present techniques for water treatment such as piped, treated water rely on time and resource intensive centralized solutions. In this work, we propose a decentralized...... sufficiently weakly, such as SnO2, can activate hydrogen peroxide evolution. We present a rational design principle for the selectivity in electrochemical water oxidation and identify new material candidates that could perform H2O2 evolution selectively....

  10. Impact of hydrogen peroxide activated by lighting-emitting diode/laser system on enamel color and microhardness: An in situ design

    Science.gov (United States)

    Loiola, Ana Bárbara Araújo; Souza-Gabriel, Aline Evangelista; Scatolin, Renata Siqueira; Corona, Silmara Aparecida Milori

    2016-01-01

    Background: Hydrogen peroxide (HP) at lower concentration can provide less alteration on enamel surface and when combined with laser therapy, could decrease tooth sensitivity. This in situ study evaluated the influence of 15% and 35% HP gel activated by lighting-emitting diode (LED)/laser light for in-office tooth bleaching. Materials and Methods: Forty-four bovine enamel slabs were polished and subjected to surface microhardness (load of 25 g for 5 s). The specimens were placed in intraoral palatal devices of 11 volunteers (n = 11). Sample was randomly distributed into four groups according to the bleaching protocol: 15% HP, 15% HP activated by LED/laser, 35% HP, and 35% HP activated by LED/laser. The experimental phase comprised 15 days and bleaching protocols were performed on the 2nd and 9th days. Surface microhardness (KHN) and color changes were measured and data were analyzed by ANOVA (α = 0.05). Results: There were no significant differences in microhardness values neither in color alteration of enamel treated with 15% HP and 35% HP activated or not by LED/laser system (P > 0.05). Conclusions: Both concentrations of HP (15 or 35%), regardless of activated by an LED/laser light, did not affect the surface microhardness and had the same effectiveness in enamel bleaching.

  11. Efficient Electrochemical Hydrogen Peroxide Generation in Water Project

    Data.gov (United States)

    National Aeronautics and Space Administration — An electrochemical cell is proposed for the efficient generation of 3% hydrogen peroxide (H2O2) in pure water using only power, oxygen and water. H2O2 is an...

  12. A Novel Fluorescent Reagent for Analysis of Hydrogen Peroxide

    Institute of Scientific and Technical Information of China (English)

    董素英; 苏美红; 聂丽华; 马会民

    2003-01-01

    8-(4,6-Dichloro-1,3,5-trazinoxy)quinoline(DTQ) was evaluated as a new fluorescent reagent for determining hydrogen peroxide.It was found that the fluorescence intensity of DTQ in alkaline medium could be dramatically enhanced upon addition of H2O2.Based on this effect,a simple and selective method for the spectrofluorimetric determination of hydrogen peroxide was estabhlished.The relative standard deviation of the method was found to be 1.1?for 9 replicate determinations of a 4.6×10-6mol/L hydrogen peroxide solution.The linear range was 2.3×10-7-2.3×10-5mol/L with a detection limit of 2.2×10-8mol/L(S/N=3).The ,method was attempted to determine hydrogen peroxide in synthetic human serum samples with satisfactory results.

  13. HE EFFECT OF TRANSITION METAL IONS-IRON ON HYDROGEN PEROXIDE BLEACHING

    Institute of Scientific and Technical Information of China (English)

    Yumeng Zhao; Shuhui Yang; Liang Sheng; Yonghao Ni

    2004-01-01

    Hydrogen peroxide bleaching has been extensively used in high-yield pulp bleaching. Unfortunately,hydrogen peroxide can be decomposed under alkaline condition, especially when transition metal ions exit. Experiments show that the valence of transition metal ion is also responsible for the decomposition of hydrogen peroxide.Iron ions are present in two oxidation states, Fe2+ and Fe3+. They are both catalytically active to hydrogen peroxide decomposition. Because Fe3+ is brown, it can affect the brightness of pulp directly, it can also combine with phenol, forming complexes which not only are stable structures and are difficult to be removed from pulp, but also significantly affect the brightness of pulp because of their color.Sodium silicate and magnesium sulfate, when used together, can greatly decrease hydrogen peroxide decomposition. The optimum dosage of sodium silicate is about 0.1% (on solution) for Fe2+ and 0.25% (on solution) for Fe3+. Adding chelants such as DTPA or EDTA with stabilizers simultaneously can obviously improve pulp brightness. For iron ions, the chelate effect of DTPA is better than that of EDTA.Under acidic conditions, sodium hyposulfite and cellulose can reduce Fe3+ to Fe2+ effectively, and pulp brightness is improved greatly. Adding sodium thiosulfate simultaneously with magnesium sulfate,sodium silicate, and DTPA to alkaline peroxide solution can result in higher brightness of pulp.pH is a key parameter during hydrogen peroxide bleaching, the optimum pH value should be 10.5-12.

  14. Antioxidant Activity/Capacity Measurement. 2. Hydrogen Atom Transfer (HAT)-Based, Mixed-Mode (Electron Transfer (ET)/HAT), and Lipid Peroxidation Assays.

    Science.gov (United States)

    Apak, Reşat; Özyürek, Mustafa; Güçlü, Kubilay; Çapanoğlu, Esra

    2016-02-10

    Measuring the antioxidant activity/capacity levels of food extracts and biological fluids is useful for determining the nutritional value of foodstuffs and for the diagnosis, treatment, and follow-up of numerous oxidative stress-related diseases. Biologically, antioxidants play their health-beneficial roles via transferring a hydrogen (H) atom or an electron (e(-)) to reactive species, thereby deactivating them. Antioxidant activity assays imitate this action; that is, antioxidants are measured by their H atom transfer (HAT) or e(-) transfer (ET) to probe molecules. Antioxidant activity/capacity can be monitored by a wide variety of assays with different mechanisms, including HAT, ET, and mixed-mode (ET/HAT) assays, generally without distinct boundaries between them. Understanding the principal mechanisms, advantages, and disadvantages of the measurement assays is important for proper selection of method for valid evaluation of antioxidant properties in desired applications. This work provides a general and up-to-date overview of HAT-based, mixed-mode (ET/HAT), and lipid peroxidation assays available for measuring antioxidant activity/capacity and the chemistry behind them, including a critical evaluation of their advantages and drawbacks. PMID:26805392

  15. Antioxidant Activity/Capacity Measurement. 2. Hydrogen Atom Transfer (HAT)-Based, Mixed-Mode (Electron Transfer (ET)/HAT), and Lipid Peroxidation Assays.

    Science.gov (United States)

    Apak, Reşat; Özyürek, Mustafa; Güçlü, Kubilay; Çapanoğlu, Esra

    2016-02-10

    Measuring the antioxidant activity/capacity levels of food extracts and biological fluids is useful for determining the nutritional value of foodstuffs and for the diagnosis, treatment, and follow-up of numerous oxidative stress-related diseases. Biologically, antioxidants play their health-beneficial roles via transferring a hydrogen (H) atom or an electron (e(-)) to reactive species, thereby deactivating them. Antioxidant activity assays imitate this action; that is, antioxidants are measured by their H atom transfer (HAT) or e(-) transfer (ET) to probe molecules. Antioxidant activity/capacity can be monitored by a wide variety of assays with different mechanisms, including HAT, ET, and mixed-mode (ET/HAT) assays, generally without distinct boundaries between them. Understanding the principal mechanisms, advantages, and disadvantages of the measurement assays is important for proper selection of method for valid evaluation of antioxidant properties in desired applications. This work provides a general and up-to-date overview of HAT-based, mixed-mode (ET/HAT), and lipid peroxidation assays available for measuring antioxidant activity/capacity and the chemistry behind them, including a critical evaluation of their advantages and drawbacks.

  16. Strategies for designing supported gold-palladium bimetallic catalysts for the direct synthesis of hydrogen peroxide.

    Science.gov (United States)

    Edwards, Jennifer K; Freakley, Simon J; Carley, Albert F; Kiely, Christopher J; Hutchings, Graham J

    2014-03-18

    Hydrogen peroxide is a widely used chemical but is not very efficient to make in smaller than industrial scale. It is an important commodity chemical used for bleaching, disinfection, and chemical manufacture. At present, manufacturers use an indirect process in which anthraquinones are sequentially hydrogenated and oxidized in a manner that hydrogen and oxygen are never mixed. However, this process is only economic at a very large scale producing a concentrated product. For many years, the identification of a direct process has been a research goal because it could operate at the point of need, producing hydrogen peroxide at the required concentration for its applications. Research on this topic has been ongoing for about 100 years. Until the last 10 years, catalyst design was solely directed at using supported palladium nanoparticles. These catalysts require the use of bromide and acid to arrest peroxide decomposition, since palladium is a very active catalyst for hydrogen peroxide hydrogenation. Recently, chemists have shown that supported gold nanoparticles are active when gold is alloyed with palladium because this leads to a significant synergistic enhancement in activity and importantly selectivity. Crucially, bimetallic gold-based catalysts do not require the addition of bromide and acids, but with carbon dioxide as a diluent its solubility in the reaction media acts as an in situ acid promoter, which represents a greener approach for peroxide synthesis. The gold catalysts can operate under intrinsically safe conditions using dilute hydrogen and oxygen, yet these catalysts are so active that they can generate peroxide at commercially significant rates. The major problem associated with the direct synthesis of hydrogen peroxide concerns the selectivity of hydrogen usage, since in the indirect process this factor has been finely tuned over decades of operation. In this Account, we discuss how the gold-palladium bimetallic catalysts have active sites for the

  17. Effects of hydrogen peroxide on mitochondrial gene expression of intestinal epithelial cells

    Institute of Scientific and Technical Information of China (English)

    Jian-Ming Li; Qian Cai; Hong Zhou; Guang-Xia Xiao

    2002-01-01

    AIM: To study the effects of hydrogen peroxide on mitochondrial gene expression of intestinal epithelial cells in in vitro model of hydrogen peroxide-stimulated SW-480 cells.METHODS: RNA of hydrogen peroxide-induced SW-480 cells was isolated, and reverse-transcriptional polymerase chain reaction was performed to study gene expression of ATPase subunit 6, ATPase subunit 8, cytochrome c oxidase subunit Ⅰ (COⅠ), cytochrome coxidase subuit Ⅱ (COⅡ) and cytochrome c oxidase subunit Ⅲ (COⅢ). Mitochondria were isolated and activities of mitochondrial cytochrome c oxidase and ATPase were also measured simultaneously.RESULTS: Hydrogen peroxide led to differential expression of mitochondrial genes with some genes up-regulated or down-regulated in a dose dependent manner. Differences were very obvious in expressions of mitochondrial genes of cells treated with hydrogen peroxide in a concentration of 400 μmol/L or 4 mmol/L. In general, differential expression of mitochondrial genes was characterized by up-regulation of mitochondrial genes in the concentration of 400 μmol/L and down-regulation in the concentration of 4 mmol/L. In consistence with changes in mitochondrial gene expressions, hydrogen peroxide resulted in decreased activities of cytochrome c oxidase and ATPase.CONCLUSIONS: The differential expression of mitochondrial genes encoding cytochrome c oxidase and ATPase is involved in apoptosis of intestinal epithelial cells by affecting activities of cytochorme c oxidase and ATPase.

  18. Localised hydrogen peroxide sensing for reproductive health

    Science.gov (United States)

    Purdey, Malcolm S.; Schartner, Erik P.; Sutton-McDowall, Melanie L.; Ritter, Lesley J.; Thompson, Jeremy G.; Monro, Tanya M.; Abell, Andrew D.

    2015-05-01

    The production of reactive oxygen species (ROS) is known to affect the developmental competence of embryos. Hydrogen peroxide (H2O2) an important reactive oxygen species, is also known to causes DNA damage and defective sperm function. Current techniques require incubating a developing embryo with an organic fluorophore which is potentially hazardous for the embryo. What we need is a localised ROS sensor which does not require fluorophores in solution and hence will allow continuous monitoring of H2O2 production without adversely affect the development of the embryo. Here we report studies on such a fibre-based sensor for the detection of H2O2 that uses a surface-bound aryl boronate fluorophore carboxyperoxyfluor-1(CPF1). Optical fibres present a unique platform due to desirable characteristics as dip sensors in biological solutions. Attempts to functionalise the fibre tips using polyelectrolyte layers and (3-aminopropyl)triethoxysilane (APTES) coatings resulted in a limited signal and poor fluorescent response to H2O2 due to a low tip surface density of the fluorophore. To increase the surface density, CPF1 was integrated into a polymer matrix formed on the fibre tip by a UV-catalysed polymerisation process of acrylamide onto a methacrylate silane layer. The polyacrylamide containing CPF1 gave a much higher surface density than previous surface attachment methods and the sensor was found to effectively detect H2O2. Using this method, biologically relevant concentrations of H2O2 were detected, enabling remote sensing studies into ROS releases from embryos throughout early development.

  19. Reduction of hydrogen peroxide-induced erythrocyte damage by Carica papaya leaf extract

    Institute of Scientific and Technical Information of China (English)

    Tebekeme Okoko; Diepreye Ere

    2012-01-01

    Objective: To investigate the in vitro antioxidant potential of Carica papaya (C. papaya) leaf extract and its effect on hydrogen peroxide-induced erythrocyte damage assessed by haemolysis and lipid peroxidation. Methods: Hydroxyl radical scavenging activities, hydrogen ion scavenging activity, metal chelating activity, and the ferrous ion reducing ability were assessed as antioxidant indices. In the other experiment, human erythrocytes were treated with hydrogen peroxide to induce erythrocyte damage. The extract (at various concentrations) was subsequently incubated with the erythrocytes and later analysed for haemolysis and lipid peroxidation as indices for erythrocyte damage. Results:Preliminary investigation of the extract showed that the leaf possessed significant antioxidant and free radical scavenging abilities using in vitro models in a concentration dependent manner (P<0.05). The extract also reduced hydrogen peroxide induced erythrocyte haemolysis and lipid peroxidation significantly when compared with ascorbic acid (P<0.05). The IC50 values were 7.33 mg/mL and 1.58 mg/mL for inhibition of haemolysis and lipid peroxidation, respectively. In all cases, ascorbic acid (the reference antioxidant) possessed higher activity than the extract. Conclusions:The findings show that C. papaya leaves possess significant bioactive potential which is attributed to the phytochemicals which act in synergy. Thus, the leaves can be exploited for pharmaceutical and nutritional purposes.

  20. Diesel autothermal reforming with hydrogen peroxide for low-oxygen environments

    International Nuclear Information System (INIS)

    Highlights: • The concept of diesel reforming using hydrogen peroxide was newly proposed. • Characteristics of hydrogen peroxide was experimentally investigated. • Thermodynamically possible operating conditions were analyzed. • Catalytic performance of Ni–Ru/CGO for various diesel compounds was evaluated. • Long-term testing was successfully conducted using Korean commercial diesel. - Abstract: To operate fuel cells effectively in low-oxygen environments, such as in submarines and unmanned underwater vehicles, a hydrogen source with high hydrogen storage density is required. In this paper, diesel autothermal reforming (ATR) with hydrogen peroxide as an alternative oxidant is proposed as a hydrogen production method. Diesel fuel has higher hydrogen density than metal hydrides or other hydrocarbons. In addition, hydrogen peroxide can decompose into steam and oxygen, which are required for diesel ATR. Moreover, both diesel fuel and hydrogen peroxide are liquid states, enabling easy storage for submarine applications. Hydrogen peroxide exhibited the same characteristics as steam and oxygen when used as an oxidant in diesel reforming when pre-decomposition method was used. The thermodynamically calculated operating conditions were a steam-to-carbon ratio (SCR) of 3.0, an oxygen-to-carbon ratio (OCR) of 0.5, and temperatures below 700 °C to account for safety issues associated with hydrogen peroxide use and exothermic reactions. Catalytic activity and stability tests over Ni–Ru (19.5–0.5 wt.%)/Ce0.9Gd0.1O2−x were conducted using various diesel compounds. Furthermore, long-term diesel ATR tests were conducted for 200 h using Korean commercial diesel. The degradation rate was 3.67%/100 h without the production of ethylene

  1. Hydrogen Peroxide and Sodium Transport in the Lung and Kidney

    Directory of Open Access Journals (Sweden)

    V. Shlyonsky

    2016-01-01

    Full Text Available Renal and lung epithelial cells are exposed to some significant concentrations of H2O2. In urine it may reach 100 μM, while in the epithelial lining fluid in the lung it is estimated to be in micromolar to tens-micromolar range. Hydrogen peroxide has a stimulatory action on the epithelial sodium channel (ENaC single-channel activity. It also increases stability of the channel at the membrane and slows down the transcription of the ENaC subunits. The expression and the activity of the channel may be inhibited in some other, likely higher, oxidative states of the cell. This review discusses the role and the origin of H2O2 in the lung and kidney. Concentration-dependent effects of hydrogen peroxide on ENaC and the mechanisms of its action have been summarized. This review also describes outlooks for future investigations linking oxidative stress, epithelial sodium transport, and lung and kidney function.

  2. Different Modes of Hydrogen Peroxide Action During Seed Germination.

    Science.gov (United States)

    Wojtyla, Łukasz; Lechowska, Katarzyna; Kubala, Szymon; Garnczarska, Małgorzata

    2016-01-01

    Hydrogen peroxide was initially recognized as a toxic molecule that causes damage at different levels of cell organization and thus losses in cell viability. From the 1990s, the role of hydrogen peroxide as a signaling molecule in plants has also been discussed. The beneficial role of H2O2 as a central hub integrating signaling network in response to biotic and abiotic stress and during developmental processes is now well established. Seed germination is the most pivotal phase of the plant life cycle, affecting plant growth and productivity. The function of hydrogen peroxide in seed germination and seed aging has been illustrated in numerous studies; however, the exact role of this molecule remains unknown. This review evaluates evidence that shows that H2O2 functions as a signaling molecule in seed physiology in accordance with the known biology and biochemistry of H2O2. The importance of crosstalk between hydrogen peroxide and a number of signaling molecules, including plant phytohormones such as abscisic acid, gibberellins, and ethylene, and reactive molecules such as nitric oxide and hydrogen sulfide acting on cell communication and signaling during seed germination, is highlighted. The current study also focuses on the detrimental effects of H2O2 on seed biology, i.e., seed aging that leads to a loss of germination efficiency. The dual nature of hydrogen peroxide as a toxic molecule on one hand and as a signal molecule on the other is made possible through the precise spatial and temporal control of its production and degradation. Levels of hydrogen peroxide in germinating seeds and young seedlings can be modulated via pre-sowing seed priming/conditioning. This rather simple method is shown to be a valuable tool for improving seed quality and for enhancing seed stress tolerance during post-priming germination. In this review, we outline how seed priming/conditioning affects the integrative role of hydrogen peroxide in seed germination and aging. PMID:26870076

  3. Atmospheric hydrogen peroxide and methyl hydroperoxide in Yanbian, China

    Science.gov (United States)

    Kim, Y.; Ji, B.; Lee, M.; Kim, K.; Lee, G.

    2003-04-01

    Hydrogen peroxide and organic peroxides are photochemical byproducts. They are referred as the indicator of oxidizing capacity of the atmosphere. Further, they are related with the production and removal of ozone in photochemistry. To better understand the photochemical processes in the troposphere, it is essential to know the correct concentration of hydroperoxides. Hydrogen peroxide and methyl Hydroperoxide were measured from 24 Aug to 3 Sep in Yanbian, China. Measurements were made for continuously during the whole course of the experiments. After collected in aqueous solution using continuous scrubbing coil, hydroperoxides were separated by HPLC, and then quantified by fluorescence produced using postcolumn enzyme derivatization. Collection and analysis were done automatically Average concentration of hydrogen peroxide and methyl hydroperoxide were 0.9ppbc and 1.6 ppb, respectively. In general, hydroperoxides showed typical diurnal variations with the maximum concentration during day. It was the first study of air pollution conducted in Yanbian, China. Detailed results will be presented in the meeting.

  4. Effect of Hydrogen Peroxide on the Antibacterial Substantivity of Chlorhexidine

    Directory of Open Access Journals (Sweden)

    Shahriar Shahriari

    2010-01-01

    Full Text Available The purpose of this in vitro study was to assess the effect of hydrogen peroxide on the antibacterial substantivity of chlorhexidine (CHX. Seventy-five dentine tubes prepared from human maxillary central and lateral incisor teeth were used. After contamination with Enterococcus faecalis for 14 days, the specimens were divided into five groups as follows: CHX, H2O2, CHX + H2O2, infected dentine tubes (positive control, and sterile dentine tubes (negative control. Dentine chips were collected with round burs into tryptic soy broth, and after culturing, the number of colony-forming units (CFU was counted. The number of CFU was minimum in the first cultures in all experimental groups, and the results obtained were significantly different from each other at any time period (<.05. At the first culture, the number of CFU in the CHX + H2O2 group was lower than other two groups. At the other experimental periods, the CHX group showed the most effective antibacterial action (<.05. Hydrogen peroxide group showed the worst result at all periods. In each group, the number of CFU increased significantly by time lapse (<.05. In conclusion, H2O2 had no additive effect on the residual antibacterial activity of CHX.

  5. Hydrogen peroxide is produced by E. coli challenged haemocytes and regulates phagocytosis, in the medfly Ceratitis capitata. The active role of superoxide dismutase.

    Science.gov (United States)

    Arbi, Marina; Pouliliou, Stamatia; Lampropoulou, Maria; Marmaras, Vassilis J; Tsakas, Sotiris

    2011-08-01

    Hydrogen peroxide (H(2)O(2)) participates as a second messenger in cell signaling. In this paper, the role of H(2)O(2) was investigated, in Escherichia coli phagocytosis by the haemocytes of the medfly Ceratitis capitata. Block of H(2)O(2) synthesis by specific enzymic inhibitors, namely N-ethylmaleimide (NEM) for NADPH oxidase and diethyldithiocarbamate (DDC) for SOD, resulted in the increase of E. coli phagocytosis. Immunoblot analysis, flow cytometry and confocal microscopy, revealed the constitutive expression of SOD, in the medfly haemocytes. Phagocytosis increased by small interfering RNA (siRNA) for SOD, revealing the active involvement of SOD and H(2)O(2). Immunoblot analysis showed an increase of the ERK1/2 phosphorylation, in the presence of the above H(2)O(2) synthesis enzymic inhibitors. In addition, confocal microscopy showed no co-localization of SOD with β integrin subunit. It appears that SOD participates in the regulation of bacterial phagocytosis, due to involvement of the produced H(2)O(2) in the differential phosphorylation of MAP kinases.

  6. Resolvin-D1 inhibits interleukin-8 and hydrogen peroxide production induced by cigarette smoke extract in 16HBE cells via attenuating NF-κB activation

    Institute of Scientific and Technical Information of China (English)

    Dong Jiajia; Zhang Mingke; Liao Zenglin; Wu Wei; Wang Tao; Chen Lei; Yang Ting

    2014-01-01

    Background Cigarette smoke induced airway inflammation plays a role in pathogenesis of airway inflammation.Resolvin-D1 derived from omega-3 polyunsaturated fatty acids is an endogenous anti-inflammatory and proresolving lipid mediator.Resolvin-D1 ameliorated inflammatory responses in lung injury,asthma,peritonitis and atherosclerosis.We investigated whether resolvin-D1 suppressed the productions of chemokines and oxidative stress induced by cigarette smoke extract (CSE) in vitro and its possible mechanism.Methods We examined the proinfiammatory chemokine interleukin-8 and hydrogen peroxide (H2O2)productions induced by CSE in 16 human bronchial epithelial (16HBE)cells after resolvin-D1 treatment and their mechanisms.16HBE cells were treated with resolvin-D1 at up to 10 nmol/L,for 30 minutes before CSE up to 16% (v/v) exposure.Release of interlukin-8 proteins was assessed by enzyme linked immunosort assay (ELISA) and its mRNA level by RT-PCR.We evaluated extracellular H2O2 expression in the supematant.Phosphorylation of NF-KB/p65 and degradation of Ⅰ-KB in 16HBE cells were determined by Westem blotting analysis and NF-KB DNA binding activity by electrophoretic mobility shift assay (EMSA).Results 16HBE cells treated with 8% CSE showed significantly higher interlukin-8 production.Resolvin-D1 pretreatment inhibited CSE induced intedukin-8 production (mRNA and protein) in a dose and time dependent manner.Extracellular H2O2 level decreased after resolvin-D1 treatment.Resolvin-D1 attenuated CSE triggered Ⅰ-KB degradation and NF-KB/p65 activation dose dependently and inhibited NF-KB DNA binding activity.Conclusion Resolvin-D1 inhibits CSE induced interlukin-8 and H2O2 production in 16HBE cells by modulating NF-KB activation and has therapeutic potential for pulmonary inflammation.

  7. Probing skin interaction with hydrogen peroxide using diffuse reflectance spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Zonios, George [Department of Materials Science and Engineering, University of Ioannina, 45110 Ioannina (Greece); Dimou, Aikaterini [Department of Materials Science and Engineering, University of Ioannina, 45110 Ioannina (Greece); Galaris, Dimitrios [Laboratory of Biological Chemistry, School of Medicine, University of Ioannina, 45110 Ioannina (Greece)

    2008-01-07

    Hydrogen peroxide is an important oxidizing agent in biological systems. In dermatology, it is frequently used as topical antiseptic, it has a haemostatic function, it can cause skin blanching, and it can facilitate skin tanning. In this work, we investigated skin interaction with hydrogen peroxide, non-invasively, using diffuse reflectance spectroscopy. We observed transient changes in the oxyhaemoglobin and deoxyhaemoglobin concentrations as a result of topical application of dilute H{sub 2}O{sub 2} solutions to the skin, with changes in deoxyhaemoglobin concentration being more pronounced. Furthermore, we did not observe any appreciable changes in melanin absorption properties as well as in the skin scattering properties. We also found no evidence for production of oxidized haemoglobin forms. Our observations are consistent with an at least partial decomposition of hydrogen peroxide within the stratum corneum and epidermis, with the resulting oxygen and/or remaining hydrogen peroxide inducing vasoconstriction to dermal blood vessels and increasing haemoglobin oxygen saturation. An assessment of the effects of topical application of hydrogen peroxide to the skin may serve as the basis for the development of non-invasive techniques to measure skin antioxidant capacity and also may shed light onto skin related disorders such as vitiligo.

  8. Probing skin interaction with hydrogen peroxide using diffuse reflectance spectroscopy

    Science.gov (United States)

    Zonios, George; Dimou, Aikaterini; Galaris, Dimitrios

    2008-01-01

    Hydrogen peroxide is an important oxidizing agent in biological systems. In dermatology, it is frequently used as topical antiseptic, it has a haemostatic function, it can cause skin blanching, and it can facilitate skin tanning. In this work, we investigated skin interaction with hydrogen peroxide, non-invasively, using diffuse reflectance spectroscopy. We observed transient changes in the oxyhaemoglobin and deoxyhaemoglobin concentrations as a result of topical application of dilute H2O2 solutions to the skin, with changes in deoxyhaemoglobin concentration being more pronounced. Furthermore, we did not observe any appreciable changes in melanin absorption properties as well as in the skin scattering properties. We also found no evidence for production of oxidized haemoglobin forms. Our observations are consistent with an at least partial decomposition of hydrogen peroxide within the stratum corneum and epidermis, with the resulting oxygen and/or remaining hydrogen peroxide inducing vasoconstriction to dermal blood vessels and increasing haemoglobin oxygen saturation. An assessment of the effects of topical application of hydrogen peroxide to the skin may serve as the basis for the development of non-invasive techniques to measure skin antioxidant capacity and also may shed light onto skin related disorders such as vitiligo.

  9. Probing skin interaction with hydrogen peroxide using diffuse reflectance spectroscopy

    International Nuclear Information System (INIS)

    Hydrogen peroxide is an important oxidizing agent in biological systems. In dermatology, it is frequently used as topical antiseptic, it has a haemostatic function, it can cause skin blanching, and it can facilitate skin tanning. In this work, we investigated skin interaction with hydrogen peroxide, non-invasively, using diffuse reflectance spectroscopy. We observed transient changes in the oxyhaemoglobin and deoxyhaemoglobin concentrations as a result of topical application of dilute H2O2 solutions to the skin, with changes in deoxyhaemoglobin concentration being more pronounced. Furthermore, we did not observe any appreciable changes in melanin absorption properties as well as in the skin scattering properties. We also found no evidence for production of oxidized haemoglobin forms. Our observations are consistent with an at least partial decomposition of hydrogen peroxide within the stratum corneum and epidermis, with the resulting oxygen and/or remaining hydrogen peroxide inducing vasoconstriction to dermal blood vessels and increasing haemoglobin oxygen saturation. An assessment of the effects of topical application of hydrogen peroxide to the skin may serve as the basis for the development of non-invasive techniques to measure skin antioxidant capacity and also may shed light onto skin related disorders such as vitiligo

  10. Hydrogen peroxide induces the activation of the phospholipase C-γ1 survival pathway in PC12 cells: protective role in apoptosis

    Institute of Scientific and Technical Information of China (English)

    Wenli Yuan; Jiazhi Guo; Xingguo Li; Zhirong Zou; Guangxue Chen; Jun Sun; Tinghua Wang; Di Lu

    2009-01-01

    It has been reported that phospholipase C-γ1 (PLC-γ1) plays an important protective role in hydrogen peroxide (H2O2)-induced pheochromocytoma (PC) 12 cells death. However, most studies have used high doses of H2O2 and the downstream targets of PLC-γ1 activation remain to be identified. The present study was designed to examine the roles of PLC-γ1 signaling pathway in the apoptosis of PC12 cells induced by low dose of H2O2, as well as the downstream factors involved in this pathway. Low-dose treatment of H2O2 resulted in PLC-γ1 tyrosine phosphorylation in a time-dependent manner and H2O2 killed the PC12 cells by inducing necrosis. In contrast, pretreatment of PC12 cells with U73122, a specific inhibitor of PLC, markedly increased the percentage of dead cells. The mode of cell death was converted to apoptosis as determined by Hoechst/PI nuclear staining and fluorescence microscopy. Western blot analysis demonstrated that the expression of Bcl-2 protein and the activation of pro-caspase-3 were not significantly affected by low dose of H2O2 alone. However, after pretreatment with U73122, Bcl-2 protein expression was dramatically decreased and the activation of pro-caspase-3 was sig-nificantly increased. We concluded that PLC-γ1 plays an important protective role in H2O2-induced PC12 cells death. Bcl-2 and caspase-3 probably participate in the signaling pathway as downstream factors.

  11. Oxidative desulfurization of Tufanbeyli coal by hydrogen peroxide solution

    Energy Technology Data Exchange (ETDEWEB)

    Guru, M.; Sarioz, B.V.; Cakanyildirim, C. [Gazi University, Ankara (Turkey). Dept. of Chemical Engineering

    2008-07-01

    It is becoming popular to use fossil fuels efficiently since the necessary energy is mostly supplied from fossil fuels. Altough there are high lignite reserves, high sulfur content limits the efficient use of them. In this article, we aimed to convert combustible sulfur in coal to non-combustible sulfate form in the ash by oxidizing it with a hydrogen peroxide solution. The parameters affecting the sulfur conversion were determined to be: hydrogen peroxide concentration, reaction time, mean particle size at constant room temperature and shaking rate. The maximum desulfurization efficiency reached was 74% of the original combustible sulfur with 15% (w/w) hydrogen peroxide solution, 12 hours of reaction time, and 0.25 mm mean particle size.

  12. Modeling the oxidation of phenolic compounds by hydrogen peroxide photolysis.

    Science.gov (United States)

    Zhang, Tianqi; Cheng, Long; Ma, Lin; Meng, Fanchao; Arnold, Robert G; Sáez, A Eduardo

    2016-10-01

    Hydrogen peroxide UV photolysis is among the most widely used advanced oxidation processes (AOPs) for the destruction of trace organics in waters destined for reuse. Previous kinetic models of hydrogen peroxide photolysis focus on the dynamics of hydroxyl radical production and consumption, as well as the reaction of the target organic with hydroxyl radicals. However, the rate of target destruction may also be affected by radical scavenging by reaction products. In this work, we build a predictive kinetic model for the destruction of p-cresol by hydrogen peroxide photolysis based on a complete reaction mechanism that includes reactions of intermediates with hydroxyl radicals. The results show that development of a predictive kinetic model to evaluate process performance requires consideration of the complete reaction mechanism, including reactions of intermediates with hydroxyl radicals. PMID:27448315

  13. Glutathione and antioxidant enzymes serve complementary roles in protecting activated hepatic stellate cells against hydrogen peroxide-induced cell death

    NARCIS (Netherlands)

    Dunning, Sandra; Rehman, Atta Ur; Tiebosch, Marjolein H.; Hannivoort, Rebekka A.; Haijer, Floris W.; Woudenberg, Jannes; van den Heuvel, Fiona A. J.; Buist-Homan, Manon; Faber, Klaas Nico; Moshage, Han

    2013-01-01

    Background: In chronic liver disease, hepatic stellate cells (HSCs) are activated, highly proliferative and produce excessive amounts of extracellular matrix, leading to liver fibrosis. Elevated levels of toxic reactive oxygen species (ROS) produced during chronic liver injury have been implicated i

  14. Exercise training restores coronary arteriolar dilation to NOS activation distal to coronary artery occlusion - Role of hydrogen peroxide

    NARCIS (Netherlands)

    Thengchaisri, Naris; Shipley, Robert; Ren, Yi; Parker, Janet; Kuo, Lih

    2007-01-01

    Objective - Exercise training has been shown to restore vasodilation to nitric oxide synthase (NOS) activation in arterioles distal to coronary artery occlusion. Because reactive oxygen species are generated during NOS uncoupling and the production of vasodilator H2O2 is increased during exercise in

  15. Hydrogen Peroxide Gas Generator Cycle with a Reciprocating Pump

    Energy Technology Data Exchange (ETDEWEB)

    Whitehead, J C

    2002-06-11

    A four-chamber piston pump is powered by decomposed 85% hydrogen peroxide. The performance envelope of the evolving 400 gram pump has been expanded to 172 cc/s water flow at discharge pressures near 5 MPa. A gas generator cycle system using the pump has been tested under similar conditions of pressure and flow. The powerhead gas is derived from a small fraction of the pumped hydrogen peroxide, and the system starts from tank pressures as low as 0.2 MPa. The effects of steam condensation on performance have been evaluated.

  16. Carbonate leaching of uranium and hydrogen peroxide stabilizer therefor

    International Nuclear Information System (INIS)

    In the carbonate leaching process for the solution mining of subterranean uranium containing formations in which an injection well is drilled and completed within the uranium formation; alkaline carbonate uranium leaching solution and sufficient hydrogen peroxide are injected through the injection wells into the formation whereby uranium values are produced from production wells, characterized by providing in the leaching solution a mixture of 1-hydroxyethylidene-1,1-diphosphonic acid and an alkali metal pyrophosphate in a weight ratio of from 1 to 10 to 10 to 1, the amount of said mixture being sufficient to inhibit decomposition of the hydrogen peroxide in said leaching solution

  17. Mucoid conversion of Pseudomonas aeruginosa by hydrogen peroxide: a mechanism for virulence activation in the cystic fibrosis lung

    DEFF Research Database (Denmark)

    Mathee, K; Ciofu, O; Sternberg, C;

    1999-01-01

    The leading cause of mortality in patients with cystic fibrosis (CF) is respiratory failure due in large part to chronic lung infection with Pseudomonas aeruginosa strains that undergo mucoid conversion, display a biofilm mode of growth in vivo and resist the infiltration of polymorphonuclear...... of alginate, (ii) exhibited no detectable differences in growth rate, (iii) showed an unaltered LPS profile, (iv) were approximately 72% reduced in the amount of inducible-beta-lactamase and (v) secreted little or no LasA protease and only showed 44% elastase activity. A characteristic approximately 54 k....... These findings indicate that gene activation in bacteria by toxic oxygen radicals, similar to that found in plants and mammalian cells, may serve as a defence mechanism for the bacteria. This suggests that mucoid conversion is a response to oxygen radical exposure and that this response is a mechanism of defence...

  18. Mucoid conversion of Pseudomonas aeruginosa by hydrogen peroxide: a mechanism for virulence activation in the cystic fibrosis lung

    DEFF Research Database (Denmark)

    Mathee, Kalai; Ciofu, Oana; Sternberg, Claus;

    1999-01-01

    The leading cause of mortality in patients with cystic fibrosis (CF) is respiratory failure due in large part to chronic lung infection with Pseudomonas aeruginosa strains that undergo mucoid conversion, display a biofilm mode of growth in vivo and resist the infiltration of polymorphonuclear......) exhibited no detectable differences in growth rate, (iii) showed an unaltered LPS profile, (iv) were similar to 72% reduced in the amount of inducible-beta-lactamase and (v) secreted little or Department of Clinical no LasA protease and only showed 44% elastase activity. A characteristic similar to 54 k....... These findings indicate that gene activation in bacteria by toxic oxygen radicals, similar to that found in plants and mammalian cells, may serve as a defence mechanism for the bacteria. This suggests that mucoid conversion is a response to oxygen radical exposure and that this response is a mechanism of defence...

  19. Regulation of substantia nigra pars reticulata GABAergic neuron activity by hydrogen peroxide via flufenamic acid-sensitive channels and KATP channels

    Directory of Open Access Journals (Sweden)

    Christian R Lee

    2011-04-01

    Full Text Available 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, 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 flufenamic acid 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, with additional modulation via KATP channels to regulate SNr output.

  20. Reaction kinetics of hydrogen peroxide in teeth for teeth whitening applications

    OpenAIRE

    Fang, Grace C.

    2013-01-01

    Clinical parameters for dental whitening such as peroxide concentration and treatment time have been empirically derived. However, limited quantitative analyses examine reactivity of hydrogen peroxide on in vivo tooth stains under various catalytic settings. The wide range of possible activators and stains are challenging in creating a standardized tooth model to isolate various effects for clinical applications. This study uses three model systems to determine the effects of heat, light, met...

  1. Mitochondria are the source of hydrogen peroxide for dynamic brain-cell signaling

    OpenAIRE

    Bao, Li; Avshalumov, Marat V.; Patel, Jyoti C.; Lee, Christian R.; Miller, Evan W.; Chang, Christopher J.; Rice, Margaret E.

    2009-01-01

    Hydrogen peroxide (H2O2) is emerging as a ubiquitous small-molecule messenger in biology, particularly in the brain, but underlying mechanisms of peroxide signaling remain an open frontier for study. For example, dynamic dopamine transmission in dorsolateral striatum is regulated on a subsecond timescale by glutamate via H2O2 signaling, which activates ATP-sensitive potassium (KATP) channels to inhibit dopamine release. However, the origin of this modulatory H2O2 has been elusive. Here we add...

  2. Applications of hydrogen peroxide in electrochemical technology

    Energy Technology Data Exchange (ETDEWEB)

    Alvarez Gallegos, Alberto Armando

    1998-12-01

    It is demonstrated that hydrogen peroxide can be produced with a current efficiency of 40-70% by the cathodic reduction of oxygen at a reticulated vitreous carbon electrode in a divided flow-cell using catholytes consisting of aqueous chloride or sulphate media, pH >>{sub 2}. The supporting electrolyte does not influence either the current efficiency for H{sub 2}O{sub 2} or its rate of production. The current efficiency for H{sub 2}O{sub 2} is not a strong function of the potential and this suggests that 2e- and 4e- reduction of oxygen occurs in parallel at different sites on the carbon surface. Voltammetry experiments showed that (a) the I-E response for oxygen reduction at pH >>{sub 2} is a function of the electrode surface and/or the supporting electrolyte; (b) both H{sub 2} evolution and oxygen reduction are retarded on carbon with increasing ionic strength; (c) the presence of ferrous ions lead to the homogeneous decomposition of H{sub 2}O{sub 2} away from the cathode surface but their effectiveness as a catalyst for this decomposition depends on their speciation in solution which changes during an electrolysis. The use of a three-dimensional electrode fabricated from reticulated vitreous carbon allows Fenton`s reagent to be electroproduced at a practical rate which makes possible the removal of organics in slightly acidic aqueous media. A wide range of highly toxic organic molecules (phenol, catechol, hydroquinone, p-benzoquinone, oxalic acid, aniline, cresol and amaranth) have been oxidised in mild conditions and a significant fraction of the organic carbon is evolved as CO{sub 2}. In all cases studied the initial chemical oxygen demand (COD) was depleted to levels higher than 85%, indicating a complete mineralisation of the organic pollutants. The life-time of the reticulated vitreous carbon cathode was demonstrated to be over 1000 hours during two and a half years of experiments. During this time the cathode performance was very good, leading to

  3. Protective activity of butyrate on hydrogen peroxide-induced DNA damage in isolated human colonocytes and HT29 tumour cells.

    Science.gov (United States)

    Rosignoli, P; Fabiani, R; De Bartolomeo, A; Spinozzi, F; Agea, E; Pelli, M A; Morozzi, G

    2001-10-01

    Epidemiological studies support the involvement of short-chain fatty acids (SCFA) in colon physiology and the protective role of butyrate on colon carcinogenesis. Among the possible mechanisms by which butyrate may exert its anti-carcinogenicity an antioxidant activity has been recently suggested. We investigated the effects of butyrate and mixtures of SCFA (butyrate, propionate and acetate) on DNA damage induced by H(2)O(2) in isolated human colonocytes and in two human colon tumour cell lines (HT29 and HT29 19A). Human colonocytes were isolated from endoscopically obtained samples and the DNA damage was assessed by the comet assay. H(2)O(2) induced DNA damage in normal colonocytes in a dose-dependent manner which was statistically significant at concentrations over 10 microM. At 15 microM H(2)O(2) DNA damage in HT29 and HT29 19A cells was significantly lower than that observed in normal colonocytes (P < 0.01). Pre-incubation of the cells with physiological concentrations of butyrate (6.25 and 12.5 mM) reduced H(2)O(2) (15 microM) induced damage by 33 and 51% in human colonocytes, 45 and 75% in HT29 and 30 and 80% in HT29 19A, respectively. Treatment of cells with a mixture of 25 mM acetate + 10.4 mM propionate + 6.25 mM butyrate did not induce DNA damage, while a mixture of 50 mM acetate + 20.8 mM propionate + 12.5 mM butyrate was weakly genotoxic only towards normal colonocytes. However, both mixtures were able to reduce the H(2)O(2)-induced DNA damage by about 50% in all cell types. The reported protective effect of butyrate might be important in pathogenetic mechanisms mediated by reactive oxygen species, and aids understanding of the apparent protection toward colorectal cancer exerted by dietary fibres, which enhance the butyrate bioavailability in the colonic mucosa. PMID:11577008

  4. [The effect of cadmium chloride and hydrogen peroxide on the lipid peroxidation and fractional composition of lipids in hepatocytes of rats].

    Science.gov (United States)

    Borikov, O Iu; Kaliman, P A

    2004-01-01

    The isolated hepatocytes were incubated in the medium, containing cadmium chloride or hydrogen peroxide. Influence of the latter on the intensity of lipid peroxidation and contents of some lipids fractions, as well as viability of hepatocytes in these conditions has been studied. It is shown that under such cultivation conditions the activation of lipid peroxidation in the hepatocytes takes place. Its activation in presence of cadmium chloride was one of the factors of the membranes damage. The changes in the content of some fractions of lipids were similar both under the incubations of the cells with cadmium chloride and hydrogen peroxide. This allows one to suppose that cadmium chloride causes changes in the lipid composition of membranes as a result of intensification of lipid peroxidation. PMID:15915720

  5. Natural manganese deposits as catalyst for decomposing hydrogen peroxide

    Directory of Open Access Journals (Sweden)

    A. H. Knol

    2015-01-01

    Full Text Available Drinking water companies more and more implement Advanced Oxidation Processes (AOP in their treatment schemes to increase the barrier against organic micropollutants (OMPs. It is necessary to decompose the excessive hydrogen peroxide after applying AOP to avoid negative effects in the following, often biological, treatment steps. A drinking water company in the western part of the Netherlands investigated decomposition of about 5.75 mg L−1 hydrogen peroxide in pre-treated Meuse river water with different catalysts on pilot scale. In down flow operation, the necessary reactor Empty Bed Contact Time (EBCT with the commonly used Granulated Activated Carbon (GAC and waste ground water filter gravel (MCFgw were the same with 149 s, corresponding with a conversion rate constant r of 0.021 s−1. The EBCT of the fine coating of ground water filter gravel (MC was significantly shorter with a little more than 10 s (r = 0.30 s−1. In up flow operation, with a flow rate of 20 m h−1, the EBCT of coating MC increased till about 100 s (r = 0.031 s−1, from which can be concluded, that the performance of this waste material is better compared with GAC, in both up and down flow operation. The necessary EBCT at average filtration rate of full scale dual layer filter material (MCFsw amounted to 209 s (r = 0.015 s−1. Regarding the average residence time in the full scale filters of 700 s, applying AOP in front of the filters could be an interesting alternative which makes a separate decomposition installation superfluous, on the condition that the primary functions of the filters are not affected.

  6. Platelet-activating factor and hydrogen peroxide exert a dual modulatory effect on the transcription of LXRα and its target genes in human neutrophils.

    Science.gov (United States)

    Reyes-Quiroz, María E; Alba, Gonzalo; Sáenz, Javier; Geniz, Isabel; Jiménez, Juan; Martín-Nieto, José; Santa-María, Consuelo; Sobrino, Francisco

    2016-09-01

    Liver X receptors (LXRs) are ligand-activated nuclear receptors involved mainly in the regulation of cholesterol metabolism in many organs, including liver and intestine, as well as in macrophages and neutrophils. Besides, both anti-inflammatory and pro-inflammatory properties have been ascribed to LXRs. The effect of the inflammatory condition on the expression of LXRα and its target genes has not been previously addressed in human neutrophils. We have described that platelet-activating factor (PAF) and hydrogen peroxide (H2O2) are potent pro-inflammatory mediators that link the haemostatic and innate immune systems. In this work we report that H2O2 at low doses (1 pM-1μM) exerts an inhibitory effect on TO901317-induced mRNA expression of LXRα and of its target genes encoding the ATP-binding cassette (ABC) transporters ABCA1 and ABCG1, and the sterol regulatory element-binding protein 1c (SREBP1c). However, an opposite behaviour, i.e., a transcription-enhancing effect, was found at higher H2O2 doses (100-500μM) on most of these genes. A similar dual effect was observed when the pro-inflammatory molecule PAF was used. Interestingly, H2O2 production separately elicited by 10nM PAF or 1μM H2O2 was similarly low, and analogously, H2O2 production levels elicited by 5μM PAF or 100μM H2O2 were similarly high when they were compared. On the other hand, low doses of PAF or H2O2 induced phosphorylation of extracellular signal-regulated kinases 1 and 2 (ERK 1/2) and NF-κB activation, However, PAF or H2O2 at high doses did not produce changes in NF-κB activation levels. In summary, our results show that H2O2, either exogenous or PAF-induced, exerts a dual regulation on mRNA expression of LXRα and its target genes. PMID:27351826

  7. A PORTABLE MICROREACTOR SYSTEM TO SYNTHESIZE HYDROGEN PEROXIDE - PHASE I

    Science.gov (United States)

    In the event that vehicles of buildings become contaminated by hazardous chemical or biological materials, a well-studied and effective decontaminant is hydrogen peroxide vapor (HPV).  Unfortunately, the current technology for generating HPV requires 35 weight percent hydro...

  8. The basic chemistry and photochemistry behind hydrogen peroxide tooth whitening

    NARCIS (Netherlands)

    Young, N.D.; Fairley, P.D.; Mohan, V.; Jumeaux, C.

    2013-01-01

    Tooth whitening using hydrogen peroxide gel formulation is a complexprocess which involves both chemistry and physics, and there is still some controversy about the efficiency of whitening processes, particularly with respect to the roles of temperature and irradiation with light. In this work we av

  9. Enzymatic generation of hydrogen peroxide shows promising antifouling effect

    DEFF Research Database (Denmark)

    Kristensen, J.B.; Olsen, Stefan Møller; Laursen, B.S.;

    2010-01-01

    The antifouling (AF) potential of hydrogen peroxide (H2O2) produced enzymatically in a coating containing starch, glucoamylase, and hexose oxidase was evaluated in a series of laboratory tests and in-sea field trials. Dissolved H2O2 inhibited bacterial biofilm formation by eight of nine marine Pr...

  10. Computer Data Processing of the Hydrogen Peroxide Decomposition Reaction

    Institute of Scientific and Technical Information of China (English)

    余逸男; 胡良剑

    2003-01-01

    Two methods of computer data processing, linear fitting and nonlinear fitting, are applied to compute the rate constant for hydrogen peroxide decomposition reaction. The results indicate that not only the new methods work with no necessity to measure the final oxygen volume, but also the fitting errors decrease evidently.

  11. Mushroom extract protects against hydrogen peroxide-induced toxicity in hepatic and neuronal human cultured cells.

    Science.gov (United States)

    Guizani, Nejib; Waly, Mostafa I

    2012-11-15

    Hydrogen peroxide is an oxidative stress agent that is associated with depletion of intracellular glutathione and inhibition of antioxidant enzymes in different cell lines. Consumption of antioxidant-rich foods reduces cellular oxidative stress and its related health problems. This study aimed to assess the antioxidant properties of mushroom, Agaricus bisporous cultivar extract, against hydrogen peroxide induced oxidative stress in cultured human hepatic (HepG2) and neuronal (SH-SY5Y) cells. In this study, hydrogen peroxide caused significant oxidative stress in HepG2 and SH-SY5Y cells as demonstrated by glutathione depletion, impairment of total antioxidant capacity and inhibition of antioxidant enzymes (glutathione peroxidase, catalase and superoxide dismutase). Agaricusbisporous extract ameliorated the observed hydrogen peroxide-induced oxidative cellular insult as indicated by restoring the activity of glutathione and the assayed antioxidant enzymes to control levels. The results suggest that mushroom extract as antioxidant properties and protects against the oxidative stress induced by hydrogen peroxide-in cultured human hepatic and neuronal cells. PMID:24261122

  12. Assessment of redox changes to hydrogen peroxide-sensitive proteins during EGF signaling.

    Science.gov (United States)

    Cuddihy, Sarah L; Winterbourn, Christine C; Hampton, Mark B

    2011-07-01

    Hydrogen peroxide acts as a second messenger in growth factor signaling where it can oxidize and modify the function of redox-sensitive proteins. While selective thiol oxidation has been measured, there has been no global assessment of protein oxidation following growth factor activation. Significant changes to the abundant and widely distributed redox sensitive thiol proteins were observed in A431 epidermoid carcinoma cells exposed to hydrogen peroxide, but no changes were observed following treatment with epidermal growth factor (EGF). This included members of the peroxiredoxin family, which were also monitored in the presence of the thioredoxin reductase inhibitor auranofin to limit their capacity to recycle to the reduced form. We conclude that widespread thiol oxidation does not occur in cells during EGF signaling, and that hydrogen peroxide must act in a highly localized or selective manner.

  13. Carbon Sources for Yeast Growth as a Precondition of Hydrogen Peroxide Induced Hormetic Phenotype.

    Science.gov (United States)

    Vasylkovska, Ruslana; Petriv, Natalia; Semchyshyn, Halyna

    2015-01-01

    Hormesis is a phenomenon of particular interest in biology, medicine, pharmacology, and toxicology. In this study, we investigated the relationship between H2O2-induced hormetic response in S. cerevisiae and carbon sources in yeast growth medium. In general, our data indicate that (i) hydrogen peroxide induces hormesis in a concentration-dependent manner; (ii) the effect of hydrogen peroxide on yeast reproductive ability depends on the type of carbon substrate in growth medium; and (iii) metabolic and growth rates as well as catalase activity play an important role in H2O2-induced hormetic response in yeast. PMID:26843865

  14. Carbon Sources for Yeast Growth as a Precondition of Hydrogen Peroxide Induced Hormetic Phenotype

    Directory of Open Access Journals (Sweden)

    Ruslana Vasylkovska

    2015-01-01

    Full Text Available Hormesis is a phenomenon of particular interest in biology, medicine, pharmacology, and toxicology. In this study, we investigated the relationship between H2O2-induced hormetic response in S. cerevisiae and carbon sources in yeast growth medium. In general, our data indicate that (i hydrogen peroxide induces hormesis in a concentration-dependent manner; (ii the effect of hydrogen peroxide on yeast reproductive ability depends on the type of carbon substrate in growth medium; and (iii metabolic and growth rates as well as catalase activity play an important role in H2O2-induced hormetic response in yeast.

  15. Hydrogen peroxide as a soil amendment for greenhouse nasturtium production (Tropaeolum majus L.)

    Science.gov (United States)

    Hydrogen peroxide, H2O2, is a highly reactive oxidizing agent naturally occurring in plants and animals. Plants produce hydrogen peroxide to destroy either infected plant cells or the pathogens within a plant. Hydrogen peroxide also acts as a stress signal to plants. It is approved for the contro...

  16. Catalytic hydrogen peroxide decomposition on La1-xSrxCo03-d perovskite oxides

    NARCIS (Netherlands)

    Dam, Van-Ahn. T.; Olthuis, W.; Bergveld, P.; Berg, van den A.

    2005-01-01

    Lanthanide perovskite oxides are mentioned as material for hydrogen peroxide sensor because they can catalytically decompose hydrogen peroxide in an aqueous medium. The catalytic properties of these perovskite oxides to hydrogen peroxide are suggested due to their oxygen vacancies influenced by the

  17. 40 CFR 180.1197 - Hydrogen peroxide; exemption from the requirement of a tolerance.

    Science.gov (United States)

    2010-07-01

    ... 40 Protection of Environment 23 2010-07-01 2010-07-01 false Hydrogen peroxide; exemption from the... Exemptions From Tolerances § 180.1197 Hydrogen peroxide; exemption from the requirement of a tolerance. An exemption from the requirement of a tolerance is established for residues of hydrogen peroxide in or on...

  18. Embryotoxic effects of eight organic peroxides and hydrogen peroxide on three-day chicken embryos

    Energy Technology Data Exchange (ETDEWEB)

    Korhonen, A.; Hemminki, K.; Vainio, H.

    1984-02-01

    Nine peroxides used in rubber processing were tested for embryotoxicity in 3-day chicken embryos using the air chamber method. The potencies were expressed by the ED/sub 50/ for the total embryotoxic effect of the chemicals, including deaths and malformations, up to Day 14 of the incubation. The range of the ED/sub 50/'s was from 0.13 to 2.7 ..mu..moles per egg and the order of the potencies was as follows: cyclohexanoneperoxide > cumolhydroperoxide > ethylmethylketoneperoxide > dibenzoylperoxide > acetylacetoneperoxide > perbenzoic acid-tert-butylester > dicumylperoxide > dialauroylperoxide > hydrogen peroxide. All nine peroxides caused malformations at a moderate frequency. The maximum percentage of malformed embryos of the treated varied from the 16% of perbenzoic acid-tert-butylester to the 56% of dicumylperoxide. The high percentage caused by the latter could, however, result from slow diffusion of high lethal doses from the air chamber to the embryo.

  19. Cardiovascular responses to hydrogen peroxide into the nucleus tractus solitarius

    OpenAIRE

    Cardoso, Leonardo Máximo; Colombari, Débora Simões Almeida; Menani, José V; Toney, Glenn M.; Chianca, Deoclécio Alves; Colombari, Eduardo

    2009-01-01

    The nucleus tractus solitarius (NTS), a major hindbrain area involved in cardiovascular regulation, receives primary afferent fibers from peripheral baroreceptors and chemoreceptors. Hydrogen peroxide (H2O2) is a relatively stable and diffusible reactive oxygen species (ROS), which acting centrally, may affect neural mechanisms. In the present study, we investigated effects of H2O2 alone or combined with the glutamatergic antagonist kynurenate into the NTS on mean arterial pressure (MAP) and ...

  20. Petroleum Contaminated Soil Treatment Using Surfactant and Hydrogen Peroxide

    OpenAIRE

    Ilza Lobo; Caryna Januario Correr; Carmen Luisa Barbosa Guedes; Otavio Jorge Grigoli Abi-Saab

    2010-01-01

    The process of washing soil with surfactants, sodium lauryl ether sulphate (LESS) and sodium lauryl sulphate (SDS) was combined with chemical oxidation using hydrogen peroxide, with a view to in situ remediation of clay soil contaminated with hydrocarbons oil. The evaluation of the efficiency of the procedure was the removal of polyaromatic hydrocarbons and the comparison of physical and chemical characteristics of contaminated soil and uncontaminated from the same region. The combination of ...

  1. Hydrogen peroxide propulsion for smaller satellites (SSC98-VIII-1)

    Energy Technology Data Exchange (ETDEWEB)

    Whitehead, J C

    1998-07-13

    As satellite designs shrink, providing maneuvering and control capability falls outside the realm of available propulsion technology. While cold gas has been used on the smallest satellites, hydrogen peroxide propellant is suggested as the next step in performance and cost before hydrazine. Minimal toxicity and a small scale enable benchtop propellant preparation and development testing. Progress toward low-cost thrusters and self-pressurizing tank systems is described.

  2. Ultrasonic degradation of Rhodamine B in the presence of hydrogen peroxide and some metal oxide.

    Science.gov (United States)

    Mehrdad, Abbas; Hashemzadeh, Robab

    2010-01-01

    In this research, degradation of Rodamine B in the presence of (hydrogen peroxide), (hydrogen peroxide+ultrasound), (hydrogen peroxide+aluminum oxide), (hydrogen peroxide+aluminum oxide+ultrasound with different ultrasound power), (hydrogen peroxide+iron oxide) and (hydrogen peroxide+iron oxide+ultrasound with different ultrasound power) were investigated at 25 degrees C. The apparent rate constants for the examined systems were calculated by pseudo-first-order kinetics. The results indicate that the rate of degradation was accelerated by ultrasound. The rate of degradation was increased by increasing power ultrasound. The efficiency of the (hydrogen peroxide+iron oxide+ultrasound) system for degradation of Rodamine B was higher than the others examined.

  3. Luminescent probes for detection and imaging of hydrogen peroxide

    International Nuclear Information System (INIS)

    The relevance of hydrogen peroxide (H2O2) in biological processes has been underestimated for a long time. In recent years, various reports showed that H2O2 not only acts as a cytotoxic compound appearing in the course of oxidative stress, but also functions as an important signaling molecule. Fluorescent probes (or indicators) and nanoparticles that respond selectively to hydrogen peroxide can be applied for intracellular measurements or in vivo imaging, and are superior to electrochemical methods, e. g. in terms of spatial resolution. In contrast to previous reviews that concentrated on the adoption of different probes for certain applications, this survey highlights the basic principles of different probes in terms of their chemical design, structures and functionalities. Thus, the probes are classified according to the underlying reaction mechanism: oxidation, hydrolysis, photoinduced electron transfer, and lanthanide complexation. Other assays are based on fluorescent proteins and nanoparticles, and chemi-or bioluminescent reagents. We confine this review to probes that display a more or less distinct selectivity to hydrogen peroxide. Indicators responding to reactive oxygen species (ROS) in general, or to particular other ROS, are not covered. Finally, we briefly discuss future trends and perspectives of these luminescent reporters in biomedical research and imaging. (author)

  4. Quantification of peroxide ion passage in dentin, enamel, and cementum after internal bleaching with hydrogen peroxide.

    Science.gov (United States)

    Palo, R M; Bonetti-Filho, I; Valera, M C; Camargo, C H R; Camargo, Sea; Moura-Netto, C; Pameijer, C

    2012-01-01

    The aim of this study was to evaluate the amount of peroxide passage from the pulp chamber to the external enamel surface during the internal bleaching technique. Fifty bovine teeth were sectioned transversally 5 mm below the cemento-enamel junction (CEJ), and the remaining part of the root was sealed with a 2-mm layer of glass ionomer cement. The external surface of the samples was coated with nail varnish, with the exception of standardized circular areas (6-mm diameter) located on the enamel, exposed dentin, or cementum surface of the tooth. The teeth were divided into three experimental groups according to exposed areas close to the CEJ and into two control groups (n=10/group), as follows: GE, enamel exposure area; GC, cementum exposed area; GD, dentin exposed area; Negative control, no presence of internal bleaching agent and uncoated surface; and Positive control, pulp chamber filled with bleaching agent and external surface totally coated with nail varnish. The pulp chamber was filled with 35% hydrogen peroxide (Opalescence Endo, Ultradent). Each sample was placed inside of individual flasks with 1000 μL of acetate buffer solution, 2 M (pH 4.5). After seven days, the buffer solution was transferred to a glass tube, in which 100 μL of leuco-crystal violet and 50 μL of horseradish peroxidase were added, producing a blue solution. The optical density of the blue solution was determined by spectrophotometer and converted into microgram equivalents of hydrogen peroxide. Data were submitted to Kruskal-Wallis and Dunn-Bonferroni tests (α=0.05). All experimental groups presented passage of peroxide to the external surface that was statistically different from that observed in the control groups. It was verified that the passage of peroxide was higher in GD than in GE (ppermeable than were the dentin and enamel surfaces. PMID:22621165

  5. Selective production of hydrogen peroxide and oxidation of hydrogen sulfide in an unbiased solar photoelectrochemical cell

    DEFF Research Database (Denmark)

    Zong, Xu; Chen, Hongjun; Seger, Brian;

    2014-01-01

    A solar-to-chemical conversion process is demonstrated using a photoelectrochemical cell without external bias for selective oxidation of hydrogen sulfide (H2S) to produce hydrogen peroxide (H2O2) and sulfur (S). The process integrates two redox couples anthraquinone/anthrahydroquinone and I−/I3...

  6. Electric Response of Hydrogen Peroxide-doped Water Ices: an Analog Study for Positive Hole Currents in Rocks

    Science.gov (United States)

    Stockburger, C. C.; Keller, C. T.; Gray, A.; Sornette, J.; Udom, A.; Cruikshank, D. P.; Freund, F.

    2013-12-01

    Hydrogen peroxide-doped water ices can be viewed an analog system to igneous and high-grade metamorphic rocks, which invariably contain peroxy defects, typically Si-OO-Si, and generate positive hole charge carriers when subjected to stress. By preparing pure water ice and hydrogen peroxide-doped water ices, freezing them to -80°C, allows us to control the concentration of peroxy defects (here hydrogen peroxide molecules) and study the electrical response, when the ices are subjected to stress. Blocks of pure water ice and hydrogen peroxide-doped water ices, -80°C, were prepared. Two methods to activate peroxy bonds were used: (i) stressing one end of rectangular blocks in a hydraulic press, (ii) subjecting one part of a 2-chamber plastic tray to intense ultrasound to create a gradient of activated charge carriers. In the hydraulic press experiments the pure water ice samples produced vanishingly small currents except for occasional transients, mostly negative, during fracturing of the ice. By contrast, hydrogen peroxide-doped water ices led to significant currents, consistently positive, flowing down the stress gradients. Using ultrasound as an activation method avoids fracturing. Therefore the results are much 'cleaner', not contaminated by hard-to-control fracture-induced currents. The positive sign of the currents suggests defect electrons, generated by the break-up of peroxy bonds of hydrogen peroxide molecules embedded in the ice structure, analogous to positive hole charge carriers that are stress-activated in rocks.

  7. Salidroside inhibits endogenous hydrogen peroxide induced cytotoxicity of endothelial cells.

    Science.gov (United States)

    Zhao, Xingyu; Jin, Lianhai; Shen, Nan; Xu, Bin; Zhang, Wei; Zhu, Hongli; Luo, Zhengli

    2013-01-01

    Salidroside, a phenylpropanoid glycoside isolated from Rhodiola rosea L., shows potent antioxidant property. Herein, we investigated the protective effects of salidroside against hydrogen peroxide (H2O2)-induced oxidative damage in human endothelial cells (EVC-304). EVC-304 cells were incubated in the presence or absence of low steady states of H2O2 (3-4 µM) generated by glucose oxidase (GOX) with or without salidroside. 3(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT), superoxide dismutase (SOD), malondialdehyde (MDA), and glutathione (GSH) assays were performed, together with Hoechst 33258 staining and flow cytometric analysis using Annexin-V and propidium iodide (PI) label. The results indicated that salidroside pretreatment attenuated endogenous H2O2 induced apoptotic cell death in EVC-304 cells in a dose-dependent pattern. Furthermore, Western blot data revealed that salidroside inhibited activation of caspase-3, 9 and cleavage of poly(ADP-ribose) polymerase (PARP) induced by endogenous H2O2. It also decreased the expression of Bax and rescued the balance of pro- and anti-apoptotic proteins. All these results demonstrated that salidroside may present a potential therapy for oxidative stress in cardiovascular and cerebrovascular diseases.

  8. The kinetic study of oxidation of iodine by hydrogen peroxide

    Energy Technology Data Exchange (ETDEWEB)

    Cantrel, L. [Institut de Protection et de Surete Nucleaire, IPNS, CEN Cadarache, Saint Paul lez Durance (France); Chopin, J. [Laboratoire d`Electrochimie Inorganique, ENSSPICAM, Marseille (France)

    1996-12-01

    Iodine chemistry is one of the most important subjects of research in the field of reactor safety because this element can form volatile species which represent a biological hazard for environment. As the iodine and the peroxide are both present in the sump of the containment in the event of a severe accident on a light water nuclear reactor, it can be important to improve the knowledge on the reaction of oxidation of iodine by hydrogen peroxide. The kinetics of iodine by hydrogen peroxide has been studied in acid solution using two different analytical methods. The first is a UV/Vis spectrophotometer which records the transmitted intensity at 460 nm as a function of time to follow the decrease of iodine concentration, the second is an amperometric method which permits to record the increase of iodine+1 with time thanks to the current of reduction of iodine+1 to molecular iodine. The iodine was generated by Dushman reaction and the series of investigations were made at 40{sup o}C in a continuous stirring tank reactor. The influence of the initial concentrations of iodine, iodate, hydrogen peroxide, H{sup +} ions has been determined. The kinetics curves comprise two distinct chemical phases both for molecular iodine and for iodine+1. The relative importance of the two processes is connected to the initial concentrations of [I{sub 2}], [IO{sub 3}{sup -}], [H{sub 2}O{sub 2}] and [H{sup +}]. A rate law has been determined for the two steps for molecular iodine. (author) figs., tabs., 22 refs.

  9. Amperometric mediatorless hydrogen peroxide sensor with horseradish peroxidase encapsulated in peptide nanotubes

    Directory of Open Access Journals (Sweden)

    Hamid Feyzizarnagh

    2016-03-01

    Full Text Available A mediatorless sensor with horseradish peroxidase (HRP enzymes encapsulated inside peptide nanotubes (PNTs has been proposed for amperometric detection of hydrogen peroxide. PNTs not only encapsulate the enzymes to retain their activity and stability, but also can provide direct electron transfer between an electrode and the electroactive sites of HRP without mediators. Experimental results were compared with hydroquinone (HQ-mediated electron transfer results. The PNT/HRP sensor produced a current signal comparable to the HQ/HRP sensor in the entire range of hydrogen peroxide concentrations (0–60 mM. The amperometric signal was the greatest when PNT and HQ were used together. The current signal of the PNT/HQ/HRP system increased rapidly with the hydrogen peroxide concentration while the PNT/HRP and HQ/HRP systems showed a similar increase in the rate of current with hydrogen peroxide. The current-H2O2 concentration relations of the tested systems were analyzed using the Michaelis–Menten type equation. Using PNTs as immobilizing agents for enzymes may circumvent the drawbacks of chemical mediators such as HQ that may interfere with the redox reactions and may cause toxicity problems to enzymes.

  10. Stabilization of hydrogen peroxide using tartaric acids in Fenton and fenton-like oxidation

    Energy Technology Data Exchange (ETDEWEB)

    Oh, Hyung Suk; Kim, Jeong-Jin; Kim, Young-Hun [Andong National University, Andong (Korea, Republic of)

    2016-03-15

    The stabilization of hydrogen peroxide is a key factor in the efficiency of a Fenton reaction. The stability of hydrogen peroxide was evaluated in a Fenton reaction and Fenton-like reactions in the presence of tartaric acid as a stabilizer. The interactions between ferrous or ferric iron and tartaric acid were observed through spectroscopic monitoring at variable pH around pKa{sub 1} and pKa{sub 2} of the stabilizer. Ferric iron had a strong interaction with the stabilizer, and the strong interaction was dominant above pKa{sub 2}. At a low pH, below pKa{sub 1}, the stabilizing effect was at its maximum and the prolonged life-time of hydrogen peroxide gave a higher efficiency to the oxidative degradation of nitrobenzene. In Fenton-like reactions with hematite, the acidic conditions caused dissolution of iron from an iron oxide, and an increase in iron species was the result. Tartaric acid showed a stabilizing effect on hydrogen peroxide in the Fentonlike system. The stabilization by tartaric acid might be due to an inhibition of catalytic activity of dissolved iron, and the stabilization strongly depends on the ionization state of the stabilizer.

  11. Electrochemical synthesis of hydrogen peroxide: Rotating disk electrode and fuel cell studies

    International Nuclear Information System (INIS)

    The electrochemical reduction of oxygen on various catalysts was studied using the thin-layer rotating disk electrode (RDE) method. High-surface-area carbon was modified with an anthraquinone derivative and gold nanoparticles. Polytetrafluoroethylene (PTFE) and cationic polyelectrolyte (FAA) were used as binders in the preparation of thin-film electrodes. Our primary goal was to find a good electrocatalyst for the two-electron reduction of oxygen to hydrogen peroxide. All electrochemical measurements were carried out in 0.1 M KOH. Cyclic voltammetry was used in order to characterise the surface processes of the modified electrodes in O2-free electrolyte. The RDE results revealed that the carbon-supported gold nanoparticles are active catalysts for the four-electron reduction of oxygen in alkaline solution. Anthraquinone-modified high-area carbon catalyses the two-electron reduction at low overpotentials, which is advantageous for hydrogen peroxide production. In addition, the polymer electrolyte fuel cell technology was used for the generation of hydrogen peroxide. The cell was equipped with a bipolar membrane which consisted of commercial Nafion 117 as a cation-exchange layer and FT-FAA as an anion-exchange layer. The bipolar membranes were prepared by a hot pressing method. Use of the FAA ionomer as a binder for the anthraquinone-modified carbon catalyst resulted in production of hydrogen peroxide

  12. Functionalized Carbon Nanotubes with Gold Nanoparticles to Fabricate a Sensor for Hydrogen Peroxide Determination

    Directory of Open Access Journals (Sweden)

    Halimeh Rajabzade

    2012-01-01

    Full Text Available A highly sensitive electrode was prepared based on gold nanoparticles/nanotubes/ionic liquid for measurement of Hydrogen peroxide. Gold nanoparticles of 20–25 nm were synthesized on a nanotube carbon paste electrode by cyclic voltammetry technique while the coverage was controlled by applied potential and time. The gold nanoparticles were modified to form a monolayer on CNT, followed by decoration with ionic liquid for determination of hydrogen peroxide. The experimental conditions, applied potential and pH, for hydrogen peroxide monitoring were optimized, and hydrogen peroxide was determined amperometrically at 0.3 V vs. SCE at pH 7.0. Electrocatalytic effects of gold deposited CNT were observed with respect to unmodified one. The sensitivity obtained was 5 times higher for modified one. The presence of Au particles in the matrix of CNTs provides an environment for the enhanced electrocatalytic activities. The sensor has a high sensitivity, quickly response to H2O2 and good stability. The synergistic influence of MWNT, Au particles and IL contributes to the excellent performance for the sensor. The sensor responds to H2O2 in the linear range from 0.02 µM to 0.3 mM. The detection limit was down to 0.4 µM when the signal to noise ratio is 3.

  13. DNA polymerase III requirement for repair of DNA damage caused by methyl methanesulfonate and hydrogen peroxide

    International Nuclear Information System (INIS)

    The pcbA1 mutation allows DNA replication dependent on DNA polymerase I at the restrictive temperature in polC(Ts) strains. Cells which carry pcbA1, a functional DNA polymerase I, and a temperature-sensitive DNA polymerase III gene were used to study the role of DNA polymerase III in DNA repair. At the restrictive temperature for DNA polymerase III, these strains were more sensitive to the alkylating agent methyl methanesulfonate (MMS) and hydrogen peroxide than normal cells. The same strains showed no increase in sensitivity to bleomycin, UV light, or psoralen at the restrictive temperature. The sensitivity of these strains to MMS and hydrogen peroxide was not due to the pcbAl allele, and normal sensitivity was restored by the introduction of a chromosomal or cloned DNA polymerase III gene, verifying that the sensitivity was due to loss of DNA polymerase III alpha-subunit activity. A functional DNA polymerase III is required for the reformation of high-molecular-weight DNA after treatment of cells with MMS or hydrogen peroxide, as demonstrated by alkaline sucrose sedimentation results. Thus, it appears that a functional DNA polymerase III is required for the optimal repair of DNA damage by MMS or hydrogen peroxide

  14. Chloroplastic NADPH oxidase-like activity-mediated perpetual hydrogen peroxide generation in the chloroplast induces apoptotic-like death of Brassica napus leaf protoplasts.

    Science.gov (United States)

    Tewari, Rajesh Kumar; Watanabe, Daisuke; Watanabe, Masami

    2012-01-01

    Despite extensive research over the past years, regeneration from protoplasts has been observed in only a limited number of plant species. Protoplasts undergo complex metabolic modification during their isolation. The isolation of protoplasts induces reactive oxygen species (ROS) generation in Brassica napus leaf protoplasts. The present study was conducted to provide new insight into the mechanism of ROS generation in B. napus leaf protoplasts. In vivo localization of H(2)O(2) and enzymes involved in H(2)O(2) generation and detoxification, molecular antioxidant-ascorbate and its redox state and lipid peroxidation were investigated in the leaf and isolated protoplasts. Incubating leaf strips in the macerating enzyme (ME) for different duration (3, 6, and 12 h) induced accumulation of H(2)O(2) and malondialdehyde (lipid peroxidation, an index of membrane damage) in protoplasts. The level of H(2)O(2) was highest just after protoplast isolation and subsequently decreased during culture. Superoxide generating NADPH oxidase (NOX)-like activity was enhanced, whereas superoxide dismutase (SOD) and ascorbate peroxidase (APX) decreased in the protoplasts compared to leaves. Diaminobenzidine peroxidase (DAB-POD) activity was also lower in the protoplasts compared to leaves. Total ascorbate content, ascorbate to dehydroascorbate ratio (redox state), were enhanced in the protoplasts compared to leaves. Higher activity of NOX-like enzyme and weakening in the activity of antioxidant enzymes (SOD, APX, and DAB-POD) in protoplasts resulted in excessive accumulation of H(2)O(2) in chloroplasts of protoplasts. Chloroplastic NADPH oxidase-like activity mediated perpetual H(2)O(2) generation probably induced apoptotic-like cell death of B. napus leaf protoplasts as indicated by parallel DNA laddering and decreased mitochondrial membrane potential.

  15. Catalase, but not MnSOD, inhibits glucose deprivation-activated ASK1-MEK-MAPK signal transduction pathway and prevents relocalization of Daxx: hydrogen peroxide as a major second messenger of metabolic oxidative stress.

    Science.gov (United States)

    Song, Jae J; Lee, Yong J

    2003-10-01

    Overexpression of catalase, but not manganese superoxide dismutase (MnSOD), inhibited glucose deprivation-induced cytotoxicity and c-Jun N-terminal kinase 1 (JNK1) activation in human prostate adenocarcinoma DU-145 cells. Suppression of JNK1 activation by catalase overexpression resulted from inhibition of apoptosis signal-regulating kinase 1 (ASK1) activation by preventing dissociation of thioredoxin (TRX) from ASK1. Overexpression of catalase also inhibited relocalization of Daxx from the nucleus to the cytoplasm as well as association of Daxx with ASK1 during glucose deprivation. Taken together, hydrogen peroxide (H(2)O(2)) rather than superoxide anion (O(2) (*-)) acts as a second messenger of metabolic oxidative stress to activate the ASK1-MAPK/extracellular signal-regulated kinase (ERK) kinase (MEK)-mitogen-activated protein kinase (MAPK) signal transduction pathway.

  16. Combined free nitrous acid and hydrogen peroxide pre-treatment of waste activated sludge enhances methane production via organic molecule breakdown

    Science.gov (United States)

    Zhang, Tingting; Wang, Qilin; Ye, Liu; Batstone, Damien; Yuan, Zhiguo

    2015-11-01

    This study presents a novel pre-treatment strategy using combined free nitrous acid (FNA i.e. HNO2) and hydrogen peroxide (H2O2) to enhance methane production from WAS, with the mechanisms investigated bio-molecularly. WAS from a full-scale plant was treated with FNA alone (1.54 mg N/L), H2O2 alone (10-80 mg/g TS), and their combinations followed by biochemical methane potential tests. Combined FNA and H2O2 pre-treatment substantially enhanced methane potential of WAS by 59-83%, compared to 13-23% and 56% with H2O2 pre-treatment alone and FNA pre-treatment alone respectively. Model-based analysis indicated the increased methane potential was mainly associated with up to 163% increase in rapidly biodegradable fraction with combined pre-treatment. The molecular weight distribution and chemical structure analyses revealed the breakdown of soluble macromolecules with the combined pre-treatment caused by the deamination and oxidation of the typical functional groups in proteins, polysaccharides and phosphodiesters. These changes likely improved the biodegradability of WAS.

  17. Oxidative Stress and Modulatory effects of the root extract of Phlogacanthus tubiflorus on the activity of Glutathione-S-Transferase in Hydrogen Peroxide treated Lymphocyte

    Directory of Open Access Journals (Sweden)

    Ramteke A

    2012-04-01

    Full Text Available Glutathione-S-transferase is one of the important enzyme systems that plays vital role in decomposition of lipid hydro-peroxides formed due to oxidative stress. In the present study GST activity increased in the lymphocytes treated with increasing concentration of H2O2, and decrease in the levels of GSH was observed. For similar treatment conditions LDH activity and MDA levels increased significantly leading to decrease in the cell viability. Treatment of lymphocytes with the root extract of Phlogacanthus tubiflorus (PTE resulted in dose dependent decline in the GST activity and rise in GSH levels. LDH activity and MDA levels also declined that led to the increase of cell viability. Lymphocytes pre-treated with the PTE followed by H2O2 (0.1 and 1% treatment, decline in the activity of GST and increase in GSH levels was observed. Also we have observed decline in the activity of LDH and MDA levels in the lymphocytes for both 0.1 and 1% of H2O2 though the magnitude of change was higher in the lymphocytes pre-treated with the PTE followed with 1% of H2O2 treatment. Significant increase in the cell viability for similar conditions was also observed. These findings suggest protective function of the root extracts might be through modulation of GST activity and levels of GSH and might find application in Chemomodulation in future.

  18. Photochemical formation of hydrogen peroxide in surface and ground waters exposed to sunlight

    Energy Technology Data Exchange (ETDEWEB)

    Cooper, W.J. (Florida International Univ., Miami); Zika, R.G.

    1983-05-13

    A rapid increase in the concentration of hydrogen peroxide was observed when samples of natural surface and ground water from various locations in the United States were exposed to sunlight. The hydrogen peroxide is photochemically generated from organic constitutents present in the water; humic materials are believed to be the primary agent producing the peroxide. Studies with superoxide dismutase suggest that the superoxide anion is the precursor of the peroxide.

  19. Hydrogen peroxide – production, fate and role in redox signaling of tumor cells

    OpenAIRE

    Lennicke, Claudia; Rahn, Jette; Lichtenfels, Rudolf; Wessjohann, Ludger A; Seliger, Barbara

    2015-01-01

    Hydrogen peroxide (H2O2) is involved in various signal transduction pathways and cell fate decisions. The mechanism of the so called “redox signaling” includes the H2O2-mediated reversible oxidation of redox sensitive cysteine residues in enzymes and transcription factors thereby altering their activities. Depending on its intracellular concentration and localization, H2O2 exhibits either pro- or anti-apoptotic activities. In comparison to normal cells, cancer cells are characterized by an in...

  20. The Inhibitory Effect of PIK-75 on Inflammatory Mediator Response Induced by Hydrogen Peroxide in Feline Esophageal Epithelial Cells

    Directory of Open Access Journals (Sweden)

    Jun Yeong Jeong

    2014-01-01

    Full Text Available Isoform-selective inhibitors of phosphoinositide 3-kinase (PI3K activation have an anti-inflammatory effect by reducing proinflammatory cytokines. Cultured feline esophageal epithelial cells (EEC of passages 3~4 were treated with hydrogen peroxide and PIK-75. The cell viability was measured by a MTT incorporation assay. The distribution of PI3K isoforms, p-Akt, IL-1β, and IL-8 was inferred from Western blots. The release of IL-6 was determined by ELISA. The cell morphology was not considerably different from nontreated cells if the cells were pretreated with PIK-75 and treated with 300 μM hydrogen peroxide. The density of p110α of PI3K was increased, but that of other types was not affected after the treatment with hydrogen peroxide. The density of p-Akt, when the cells were exposed to PIK-75 and hydrogen peroxide, was diminished dose dependently more than that of hydrogen peroxide treatment only. The decrease of p-Akt showed an inhibition of PI3K by PIK-75. PIK-75 dose dependently reduced the expression of IL-1β, IL-8, and the level of IL-6 compared with hydrogen peroxide treatment only. These results suggest evidence that p110α mediates esophageal inflammation and that PIK-75 has an anti-inflammatory effect by reducing proinflammatory cytokines on feline esophageal epithelial cultured cells.

  1. Vapor hydrogen peroxide as alternative to dry heat microbial reduction

    Science.gov (United States)

    Chung, S.; Kern, R.; Koukol, R.; Barengoltz, J.; Cash, H.

    2008-09-01

    The Jet Propulsion Laboratory (JPL), in conjunction with the NASA Planetary Protection Officer, has selected vapor phase hydrogen peroxide (VHP) sterilization process for continued development as a NASA approved sterilization technique for spacecraft subsystems and systems. The goal was to include this technique, with an appropriate specification, in NASA Procedural Requirements 8020.12 as a low-temperature complementary technique to the dry heat sterilization process. The VHP process is widely used by the medical industry to sterilize surgical instruments and biomedical devices, but high doses of VHP may degrade the performance of flight hardware, or compromise material compatibility. The goal for this study was to determine the minimum VHP process conditions for planetary protection acceptable microbial reduction levels. Experiments were conducted by the STERIS Corporation, under contract to JPL, to evaluate the effectiveness of vapor hydrogen peroxide for the inactivation of the standard spore challenge, Geobacillus stearothermophilus. VHP process parameters were determined that provide significant reductions in spore viability while allowing survival of sufficient spores for statistically significant enumeration. In addition to the obvious process parameters of interest: hydrogen peroxide concentration, number of injection cycles, and exposure duration, the investigation also considered the possible effect on lethality of environmental parameters: temperature, absolute humidity, and material substrate. This study delineated a range of test sterilizer process conditions: VHP concentration, process duration, a process temperature range for which the worst case D-value may be imposed, a process humidity range for which the worst case D-value may be imposed, and the dependence on selected spacecraft material substrates. The derivation of D-values from the lethality data permitted conservative planetary protection recommendations.

  2. BIOSORPTION OF CONGO RED BY HYDROGEN PEROXIDE TREATED TENDU WASTE

    Directory of Open Access Journals (Sweden)

    G. K. Nagda ، V. S. Ghole

    2009-07-01

    Full Text Available Solid wastes from agro-industrial operations can be recycled as non-conventional adsorbents if they are inert and harmless and reduce the cost of wastewater treatment. Tendu leaf Diospyros melanoxylon is the second largest forest product in India after timber and is exclusively used in making local cigarette called Bidi. Waste leaf cutting remaining after making cigarette was used in present study as a biosorbent for the removal of Congo red dye from aqueous solution. It was treated with hydrogen peroxide to obtain biosorbent with increased adsorption capacity. Batch type experiments were conducted to study the influence of different parameters such as pH, initial dye concentration and dosage of adsorbent on biosorption evaluated. The adsorption occured very fast initially and attains equilibrium within 60 min at pH= 6.2 and the equilibrium attained faster after hydrogen peroxide modification. Kinetic studies showed that the biosorption of Congo red on tendu waste followed pseudo-second-order rate equation. The data fitted well to Langmuir and Freundlich isotherm models. Comparison was done on the extent of biosorption between untreated and treated forms of the tendu waste. The maximum adsorption capacity for untreated tendu waste was found to be 46.95 mg/g, which was enhanced by 2.8 times after hydrogen peroxide treatment and was found to be 134.4 mg/g. The adsorption process was in conformity with Freundlich and Langmuir isotherms for Congo red adsorption from aqueous solution. The study demonstrated use of milder chemical treatment of tendu waste to obtain a biosorbent with enhanced dye removal capacity.

  3. THE EFFECT OF TRANSITION METAL IONS-IRON ON HYDROGEN PEROXIDE BLEACHING

    Institute of Scientific and Technical Information of China (English)

    YumengZhao; ShuhuiYang; LiangSheng; YonghaoNi

    2004-01-01

    Hydrogen peroxide bleaching has been extensivelyused in high-yield pulp bleaching. Unfortunately,hydrogen peroxide can be decomposed underalkaline condition, especially when transition metalions exit. Experiments show that the valence oftransition metal ion is also responsible for thedecomposition of hydrogen peroxide.Iron ions are present in two oxidation states, Fe2+ andFe3+. They are both catalytically active to hydrogenperoxide decomposition. Because Fe3+ is brown, itcan affect the brightness of pulp directly, it can alsocombine with phenol, forming complexes which notonly are stable structures and are difficult to beremoved from pulp, but also significantly affect thebrightness of pulp because of their color.Sodium silicate and magnesium sulfate, when usedtogether, can greatly decrease hydrogen peroxidedecomposition. The optimum dosage of sodiumsilicate is about 0.1% (on solution) for Fe2~ and0.25% (on solution) for Fe3~. Adding chelants such asDTPA or EDTA with stabilizers simultaneously canobviously improve pulp brightness. For iron ions, thechelate effect of DTPA is better than that of EDTA.Under acidic conditions, sodium hyposulfite andcellulose can reduce Fe3+ to Fez+ effectively, and pulpbrightness is improved greatly. Adding sodiumthiosulfate simultaneously with magnesium sulfate,sodium silicate, and DTPA to alkaline peroxidesolution can result in higher brightness of pulp.pH is a key parameter during hydrogen peroxidebleaching, the optimum pH value should be 10.5-12.

  4. At-home vital bleaching: a comparison of hydrogen peroxide and carbamide peroxide treatments.

    Science.gov (United States)

    Berga-Caballero, Amparo; Forner-Navarro, Leopoldo; Amengual-Lorenzo, José

    2006-01-01

    Tray bleaching of vital teeth performed at home by the patient under the dentist s supervision, whether alone or in combination with any of the in-office techniques, provides an interesting alternative to other methods employed in this type of dental treatment. This bleaching procedure applies low-concentration peroxides to the enamel by means of a custom-made mouth tray specifically designed for this purpose. The aim of this study is to examine and compare two commercially-available bleaching products, at equivalent concentrations, for use in this technique: VivaStyle (Vivadent) and FKD (Kin); the former is a 10% carbamide peroxide and the latter a 3.5% hydrogen peroxide formulation. It examines the parameters that must be monitored during the application of this type of procedure and presents 6 cases (3 treated with one of the above-mentioned products and the other 3 with the other), establishing the bleaching power of the products and the appearance and intensity of post-operatory hypersensitivity. The results obtained show that both products are effective for the purpose for which they were designed. In general, dental hypersensitivity was minimal. PMID:16388304

  5. Modular Advanced Oxidation Process Enabled by Cathodic Hydrogen Peroxide Production

    OpenAIRE

    Barazesh, JM; Hennebel, T; Jasper, JT; Sedlak, DL

    2015-01-01

    Hydrogen peroxide (H2O2) is frequently used in combination with ultraviolet (UV) light to treat trace organic contaminants in advanced oxidation processes (AOPs). In small-scale applications, such as wellhead and point-of-entry water treatment systems, the need to maintain a stock solution of concentrated H2O2 increases the operational cost and complicates the operation of AOPs. To avoid the need for replenishing a stock solution of H2O2, a gas diffusion electrode was used to generate low con...

  6. Petroleum Contaminated Soil Treatment Using Surfactant and Hydrogen Peroxide

    Directory of Open Access Journals (Sweden)

    Ilza Lobo

    2010-12-01

    Full Text Available The process of washing soil with surfactants, sodium lauryl ether sulphate (LESS and sodium lauryl sulphate (SDS was combined with chemical oxidation using hydrogen peroxide, with a view to in situ remediation of clay soil contaminated with hydrocarbons oil. The evaluation of the efficiency of the procedure was the removal of polyaromatic hydrocarbons and the comparison of physical and chemical characteristics of contaminated soil and uncontaminated from the same region. The combination of these two techniques, soil washing and application of an oxidizing agent, presented as a process of effective remediation for soils contaminated with petroleum products in subtropical regions.

  7. Hydrogen peroxide distribution, production, and decay in boreal lakes

    OpenAIRE

    Häkkinen, P J; Anesio, Alexandre Magno; Granéli, Wilhelm

    2004-01-01

    The distribution, production, and decay of hydrogen peroxide (H2O2) were studied in 10 boreal lakes of differing physical-chemical characteristics. Diurnal and vertical fluctuations in H2O2 concentration were followed in the lakes by sampling at six depths three times per day. In addition, incubations of water filtered through 0.2-mu mesh were made under artificial irradiation to study the abiotic production and decay of H2O2. H2O2 concentrations after 8 h of artificial irradiation were signi...

  8. Hydrogen Peroxide Produced by Oral Streptococci Induces Macrophage Cell Death

    OpenAIRE

    Okahashi, Nobuo; Nakata, Masanobu; Sumitomo, Tomoko; Terao, Yutaka; Kawabata, Shigetada

    2013-01-01

    Hydrogen peroxide (H2O2) produced by members of the mitis group of oral streptococci plays important roles in microbial communities such as oral biofilms. Although the cytotoxicity of H2O2 has been widely recognized, the effects of H2O2 produced by oral streptococci on host defense systems remain unknown. In the present study, we investigated the effect of H2O2 produced by Streptococcus oralis on human macrophage cell death. Infection by S. oralis was found to stimulate cell death of a THP-1 ...

  9. Hydrogen peroxide-based propulsion and power systems.

    Energy Technology Data Exchange (ETDEWEB)

    Melof, Brian Matthew; Keese, David L.; Ingram, Brian V.; Grubelich, Mark Charles; Ruffner, Judith Alison; Escapule, William Rusty

    2004-04-01

    Less toxic, storable, hypergolic propellants are desired to replace nitrogen tetroxide (NTO) and hydrazine in certain applications. Hydrogen peroxide is a very attractive replacement oxidizer, but finding acceptable replacement fuels is more challenging. The focus of this investigation is to find fuels that have short hypergolic ignition delays, high specific impulse, and desirable storage properties. The resulting hypergolic fuel/oxidizer combination would be highly desirable for virtually any high energy-density applications such as small but powerful gas generating systems, attitude control motors, or main propulsion. These systems would be implemented on platforms ranging from guided bombs to replacement of environmentally unfriendly existing systems to manned space vehicles.

  10. The effect of hydrogen peroxide on polishing removal rate in CMP with various abrasives

    Science.gov (United States)

    Manivannan, R.; Ramanathan, S.

    2009-01-01

    The effect of hydrogen peroxide in chemical mechanical planarization slurries for shallow trench isolation was investigated. The various abrasives used in this study were ceria, silica, alumina, zirconia, titania, silicon carbide, and silicon nitride. Hydrogen peroxide suppresses the polishing of silicon dioxide and silicon nitride surfaces by ceria abrasives. The polishing performances of other abrasives were either unaffected or enhanced slightly with the addition of hydrogen peroxide. The ceria abrasives were treated with hydrogen peroxide, and the polishing of the work surfaces with the treated abrasive shows that the inhibiting action of hydrogen peroxide is reversible. It was found that the effect of hydrogen peroxide as an additive is a strong function of the nature of the abrasive particle.

  11. Apparatus and method for treating pollutants in a gas using hydrogen peroxide and UV light

    Science.gov (United States)

    Cooper, Charles David (Inventor); Clausen, Christian Anthony (Inventor)

    2005-01-01

    An apparatus for treating pollutants in a gas may include a source of hydrogen peroxide, and a treatment injector for creating and injecting dissociated hydrogen peroxide into the flow of gas. The treatment injector may further include an injector housing having an inlet, an outlet, and a hollow interior extending therebetween. The inlet may be connected in fluid communication with the source of hydrogen peroxide so that hydrogen peroxide flows through the hollow interior and toward the outlet. At least one ultraviolet (UV) lamp may be positioned within the hollow interior of the injector housing. The at least one UV lamp may dissociate the hydrogen peroxide flowing through the tube. The dissociated hydrogen peroxide may be injected into the flow of gas from the outlet for treating pollutants, such as nitrogen oxides.

  12. Evaluation of vaporized hydrogen peroxide, Citrox and pH neutral Ecasol for decontamination of an enclosed area: a pilot study.

    LENUS (Irish Health Repository)

    Galvin, S

    2012-01-01

    Hydrogen peroxide, Ecasol and Citrox aerosols were each tested for their ability to kill a range of nosocomial pathogens. Hydrogen peroxide had the broadest microbicidal activity but operational issues limit its use. Ecasol was effective against all micro-organisms, except Clostridium difficile, while Citrox aerosols were not effective against Gram-negative bacilli.

  13. Hydrogenation of liquid natural rubber via diimide reduction in hydrazine hydrate/hydrogen peroxide system

    Energy Technology Data Exchange (ETDEWEB)

    Yusof, Muhammad Jefri Mohd; Jamaluddin, Naharullah; Abdullah, Ibrahim; Yusoff, Siti Fairus M. [School of Chemical Sciences and Food Technology, Faculty of Science and Technology, Universiti Kebangsaan Malaysia, 43600 Bangi, Selangor (Malaysia)

    2015-09-25

    Liquid natural rubber (LNR) with molecular weight of lower than 10{sup 5} and shorter polymeric chain than natural rubber was prepared. LNR was then hydrogenated via diimide reduction by oxidation of hydrazine hydrate with hydrogen peroxide. The unsaturated units of the rubber were converted into saturated hydrocarbon to strengthen the backbone of the polymer so it was able to resist thermal degradation. The results indicated that hydrogenation degree of the product (HLNR) could be extended to 91.2% conversion under appropriate conditions. The hydrogenated LNR (HLNR) was characterized using Fourier-Transform Infrared (FTIR) and Nuclear Magnetic Resonance (NMR) spectroscopy. The physical characteristics of HLNR were analyzed with Termogravimetric Analysis (TGA)

  14. Boronate-Based Fluorescent Probes: Imaging Hydrogen Peroxide in Living Systems

    OpenAIRE

    Lin, Vivian S.; Dickinson, Bryan C; Chang, Christopher J.

    2013-01-01

    Hydrogen peroxide, a reactive oxygen species with unique chemical properties, is produced endogenously in living systems as a destructive oxidant to ward off pathogens or as a finely tuned second messenger in dynamic cellular signaling pathways. In order to understand the complex roles that hydrogen peroxide can play in biological systems, new tools to monitor hydrogen peroxide in its native settings, with high selectivity and sensitivity, are needed. Knowledge of organic synthetic reactivity...

  15. Quantifying hydrogen peroxide in iron-containing solutions using leuco crystal violet

    OpenAIRE

    Schoonen Martin A; Pak Aimee; Strongin Daniel; Cohn Corey A

    2005-01-01

    Hydrogen peroxide is present in many natural waters and wastewaters. In the presence of Fe(II), this species decomposes to form hydroxyl radicals, that are extremely reactive. Hence, in the presence of Fe(II), hydrogen peroxide is difficult to detect because of its short lifetime. Here, we show an expanded use of a hydrogen peroxide quantification technique using leuco crystal violet (LCV) for solutions of varying pH and iron concentration. In the presence of the biocatalyst peroxidase, LCV ...

  16. Protective effects of Rheum tanguticum polysaccharide against hydrogen peroxide-induced intestinal epithelial cell injury

    Institute of Scientific and Technical Information of China (English)

    Lin-Na Liu; Qi-Bing Mei; Li Liu; Feng Zhang; Zhen-Guo Liu; Zhi-Peng Wang; Ru-Tao Wang

    2005-01-01

    AIM: To describe the effect of Rheum tanguticum polysaccharide (RTP) on hydrogen peroxide-induced human intestinal epithelial cell injury.METHODS: Hydrogen peroxide (100 μmol/L) was introduced to induce human intestinal epithelial cell injury.Cells were pretreated with RTP (30,100,300 μg/mL) for 24 h before exposure to hydrogen peroxide. Cell viability was detected by MTr assay and morphological observation.Acridine orange staining and flow cytometry were performed to assess cell apoptosis. Lactate dehydrogenase (LDH) activity, production of malondialdehyde (MDA) and superoxide dismutase (SOD) activity were measured by spectrophotometry with corresponding assay kits.RESULTS: Following exposure to H2O2, a marked decrease in cell survival and SOD activity, increased production of MDA, LDH leakage and cell apoptosis were found.Pretreatment of the cells with RTP could significantly elevate cell survival, SOD activity and decrease the level of MDA, LDH activity and cell apoptosis.CONCLUSION: RTP may have cytoprotective and antioxidant effects against H2O2-induced intestinal epithelial cell injury by inhibiting cell apoptosis and necrosis. This might be one of the possible mechanisms of RTP for the treatment of ulcerative colitis in rats.

  17. Hydrogen sulfide protects HUVECs against hydrogen peroxide induced mitochondrial dysfunction and oxidative stress.

    Directory of Open Access Journals (Sweden)

    Ya-Dan Wen

    Full Text Available BACKGROUND: Hydrogen sulfide (H₂S has been shown to have cytoprotective effects in models of hypertension, ischemia/reperfusion and Alzheimer's disease. However, little is known about its effects or mechanisms of action in atherosclerosis. Therefore, in the current study we evaluated the pharmacological effects of H₂S on antioxidant defenses and mitochondria protection against hydrogen peroxide (H₂O₂ induced endothelial cells damage. METHODOLOGY AND PRINCIPAL FINDINGS: H₂S, at non-cytotoxic levels, exerts a concentration dependent protective effect in human umbilical vein endothelial cells (HUVECs exposed to H₂O₂. Analysis of ATP synthesis, mitochondrial membrane potential (ΔΨm and cytochrome c release from mitochondria indicated that mitochondrial function was preserved by pretreatment with H₂S. In contrast, in H₂O₂ exposed endothelial cells mitochondria appeared swollen or ruptured. In additional experiments, H₂S was also found to preserve the activities and protein expressions levels of the antioxidants enzymes, superoxide dismutase, catalase, glutathione peroxidase and glutathione-S-transferase in H₂O₂ exposed cells. ROS and lipid peroxidation, as assessed by measuring H₂DCFDA, dihydroethidium (DHE, diphenyl-l-pyrenylphosphine (DPPP and malonaldehyde (MDA levels, were also inhibited by H₂S treatment. Interestingly, in the current model, D, L-propargylglycine (PAG, a selective inhibitor of cystathionine γ-lyase (CSE, abolished the protective effects of H₂S donors. INNOVATION: This study is the first to show that H₂S can inhibit H₂O₂ mediated mitochondrial dysfunction in human endothelial cells by preserving antioxidant defences. SIGNIFICANCE: H₂S may protect against atherosclerosis by preventing H₂O₂ induced injury to endothelial cells. These effects appear to be mediated via the preservation of mitochondrial function and by reducing the deleterious effects of oxidative stress.

  18. Lichen metabolites modulate hydrogen peroxide and nitric oxide in mouse macrophages.

    Science.gov (United States)

    Carlos, Iracilda Z; Quilles, Marcela B; Carli, Camila B A; Maia, Danielle C G; Benzatti, Fernanda P; Lopes, Thiago I B; Gianini, Aline S; Brum, Rosenei L; Vilegas, Wagner; dos Santos, Lourdes C; Honda, Neli K

    2009-01-01

    The activities of perlatolic acid (1), atranorin (2), and lecanoric acid (3) and their derivatives, such as orsellinates and beta-methyl orsellinates obtained by alcoholysis, were assessed for stimulation of the release of hydrogen peroxide and nitric oxide in cultures of peritoneal macrophage cells from mice. The hydrogen peroxide production was estimated by oxidation of phenol red, while the Griess reagent was used to determine the nitric oxide production. 1 and 4-methoxy-ethyl orsellinate (XVII) were the compounds that induced the greatest release of H2O2, whereas n-pentyl orsellinate (IV), iso-propyl orsellinate (V), sec-butyl orsellinate (VI), and XVII induced a small release of NO. These results indicate that lichen products and their derivatives have potential immune-modulating activities. PMID:19957434

  19. STUDY OF AZOSPIRILLUM LECTINS INFLUENCE ON HYDROGEN PEROXIDE PRODUCTION IN WHEAT-ROOTS

    Directory of Open Access Journals (Sweden)

    Alen’kina S.A.

    2009-12-01

    Full Text Available It was found that two cell-surface lectins isolated from the nitrogen-fixing soil bacterium Azospirillum brasilense Sp7 and from its mutant defective in lectin activity, A. brasilense Sp7.2.3 can stimulate rapid formation of hydrogen peroxide, associated with an increase in the activities of oxalate oxidase and peroxidase in the roots of wheat seedlings. The most advantageous and most rapidly induced pathway of hydrogen peroxide formation was the oxidation of oxalic acid by oxalate oxidase because in this case, a 10-min treatment of the roots with the lectins at 10 µg ml-1 was sufficient. The data from this study attest that the Azospirillum lectins can act as inducers of adaptation processes in the roots of wheat seedlings.

  20. Understanding the mechanism of DNA deactivation in ion therapy of cancer cells: hydrogen peroxide action*

    Science.gov (United States)

    Piatnytskyi, Dmytro V.; Zdorevskyi, Oleksiy O.; Perepelytsya, Sergiy M.; Volkov, Sergey N.

    2015-11-01

    Changes in the medium of biological cells under ion beam irradiation has been considered as a possible cause of cell function disruption in the living body. The interaction of hydrogen peroxide, a long-lived molecular product of water radiolysis, with active sites of DNA macromolecule was studied, and the formation of stable DNA-peroxide complexes was considered. The phosphate groups of the macromolecule backbone were picked out among the atomic groups of DNA double helix as a probable target for interaction with hydrogen peroxide molecules. Complexes consisting of combinations including: the DNA phosphate group, H2O2 and H2O molecules, and Na+ counterion, were considered. The counterions have been taken into consideration insofar as under the natural conditions they neutralise DNA sugar-phosphate backbone. The energy of the complexes have been determined by considering the electrostatic and the Van der Waals interactions within the framework of atom-atom potential functions. As a result, the stability of various configurations of molecular complexes was estimated. It was shown that DNA phosphate groups and counterions can form stable complexes with hydrogen peroxide molecules, which are as stable as the complexes with water molecules. It has been demonstrated that the formation of stable complexes of H2O2-Na+-PO4- may be detected experimentally by observing specific vibrations in the low-frequency Raman spectra. The interaction of H2O2 molecule with phosphate group of the double helix backbone can disrupt DNA biological function and induce the deactivation of the cell genetic apparatus. Thus, the production of hydrogen peroxide molecules in the nucleus of living cells can be considered as an additional mechanism by which high-energy ion beams destroy tumour cells during ion beam therapy. Contribution to the Topical Issue "COST Action Nano-IBCT: Nano-scale Processes Behind Ion-Beam Cancer Therapy", edited by Andrey Solov'yov, Nigel Mason, Gustavo García, Eugene

  1. Understanding the mechanism of DNA deactivation in ion therapy of cancer cells: hydrogen peroxide action

    International Nuclear Information System (INIS)

    Changes in the medium of biological cells under ion beam irradiation has been considered as a possible cause of cell function disruption in the living body. The interaction of hydrogen peroxide, a long lived molecular product of water radiolysis, with active sites of DNA macromolecule was studied, and the formation of stable DNA-peroxide complexes was considered. The phosphate groups of the macromolecule backbone were picked out among the atomic groups of DNA double helix as a probable target for interaction with hydrogen peroxide molecules. Complexes consisting of combinations including: the DNA phosphate group, H2O2 and H2O molecules, and Na+ counter-ion, were considered. The counter-ions have been taken into consideration in so far as under the natural conditions they neutralise DNA sugar-phosphate backbone. The energy of the complexes have been determined by considering the electrostatic and the Van der Waals interactions within the framework of atom-atom potential functions. As a result, the stability of various configurations of molecular complexes was estimated. It was shown that DNA phosphate groups and counter-ions can form stable complexes with hydrogen peroxide molecules, which are as stable as the complexes with water molecules. It has been demonstrated that the formation of stable complexes of H2O2- Na+-PO4- may be detected experimentally by observing specific vibrations in the low-frequency Raman spectra. The interaction of H2O2 molecule with phosphate group of the double helix backbone can disrupt DNA biological function and induce the deactivation of the cell genetic apparatus. Thus, the production of hydrogen peroxide molecules in the nucleus of living cells can be considered as an additional mechanism by which high-energy ion beams destroy tumour cells during ion beam therapy. (authors)

  2. Antifungal efficacy of hydrogen peroxide in dental unit waterline disinfection.

    Science.gov (United States)

    Szymańska, Jolanta

    2006-01-01

    The concentration and composition of fungal flora in dental unit waterlines (DUWL) were evaluated. For this purpose, water samples from unit reservoirs and high-speed handpieces, and biofilm samples from the waterline walls from units were collected. Subsequently, analogous samples from DUWL were taken before and after disinfection using agent containing hydrogen peroxide. In the examined samples, the yeast-like fungi Candida albicans and Candida curvata were found. The following species of mould were also identified: Aspergillus amstelodami, Aspergillus fumigatus, Aspergillus glaucus group, Aspergillus (=Eurotium herbariorum) repens, Citromyces spp., Geotrichum candidum, Penicillium (glabrum) frequentans, Penicillium pusillum, Penicillium turolense and Sclerotium sclerotiorum (Sclerotinia sclerotiorum). Before disinfection, Candida curvata and Candida albicans constituted the greatest proportion of the total fungi in the reservoirs water; in the water of handpieces--Candida albicans and Aspergillus glaucus group; and in the biofilm samples--Aspergillus glaucus group and Candida albicans. After disinfection, in all 3 kinds of samples, Candida albicans prevailed, constituting from 31.2-85.7 % of the total fungi. The application of agent containing hydrogen peroxide caused a significant decrease both in the number of total fungi and individual fungal species, which confirms the product effectiveness in fungal decontamination of DUWL. PMID:17196007

  3. Formation of complexes of hydrogen peroxide molecules with DNA

    International Nuclear Information System (INIS)

    A possibility for hydrogen peroxide molecules to form stable complexes with atomic groups in the DNA backbone under the irradiation of the cell medium with high-energy ions has been studied. The energy of complexes is estimated, by taking the electrostatic and van der Waals interactions into account in the framework of the atom-atom potential function method. The interaction with metal counterions, which neutralize the surface charge of a macromolecule under natural conditions, is also taken into consideration. Stable configurations are determined for various complexes consisting of the atoms belonging to a DNA phosphate group, H2O2 and H2O molecules, and a Na+ metal ion. The complexes of hydrogen peroxide molecules with DNA phosphate groups and a counterions are shown to be not less stable than their complexes with water molecules. The attachment of an H2O2 molecule to a phosphate group of the double helix backbone can block the processes of DNA biological functioning and can deactivate the genetic mechanism of a cell

  4. Hydrogen peroxide sensing, signaling and regulation of transcription factors

    Directory of Open Access Journals (Sweden)

    H. Susana Marinho

    2014-01-01

    Full Text Available The regulatory mechanisms by which hydrogen peroxide (H2O2 modulates the activity of transcription factors in bacteria (OxyR and PerR, lower eukaryotes (Yap1, Maf1, Hsf1 and Msn2/4 and mammalian cells (AP-1, NRF2, CREB, HSF1, HIF-1, TP53, NF-κB, NOTCH, SP1 and SCREB-1 are reviewed. The complexity of regulatory networks increases throughout the phylogenetic tree, reaching a high level of complexity in mammalians. Multiple H2O2 sensors and pathways are triggered converging in the regulation of transcription factors at several levels: (1 synthesis of the transcription factor by upregulating transcription or increasing both mRNA stability and translation; (ii stability of the transcription factor by decreasing its association with the ubiquitin E3 ligase complex or by inhibiting this complex; (iii cytoplasm–nuclear traffic by exposing/masking nuclear localization signals, or by releasing the transcription factor from partners or from membrane anchors; and (iv DNA binding and nuclear transactivation by modulating transcription factor affinity towards DNA, co-activators or repressors, and by targeting specific regions of chromatin to activate individual genes. We also discuss how H2O2 biological specificity results from diverse thiol protein sensors, with different reactivity of their sulfhydryl groups towards H2O2, being activated by different concentrations and times of exposure to H2O2. The specific regulation of local H2O2 concentrations is also crucial and results from H2O2 localized production and removal controlled by signals. Finally, we formulate equations to extract from typical experiments quantitative data concerning H2O2 reactivity with sensor molecules. Rate constants of 140 M−1 s−1 and ≥1.3 × 103 M−1 s−1 were estimated, respectively, for the reaction of H2O2 with KEAP1 and with an unknown target that mediates NRF2 protein synthesis. In conclusion, the multitude of H2O2 targets and mechanisms provides an opportunity for

  5. Investigation of Influential Parameters in Deep Oxidative Desulfurization of Dibenzothiophene with Hydrogen Peroxide and Formic Acid

    OpenAIRE

    Alireza Haghighat Mamaghani; Shohreh Fatemi; Mehrdad Asgari

    2013-01-01

    An effective oxidative system consisting of hydrogen peroxide, formic acid, and sulfuric acid followed by an extractive stage were implemented to remove dibenzothiophene in the simulated fuel oil. The results revealed such a great performance in the case of H2O2 in the presence of formic and sulfuric acids that led to the removal of sulfur compounds. Sulfuric acid was employed to increase the acidity of media as well as catalytic activity together with formic acid. The oxidation reaction was ...

  6. Hydrogen peroxide mobilizes Ca2+ through two distinct mechanisms in rat hepatocytes

    OpenAIRE

    Sato, Hirohiko; Takeo, Teruko; Liu, Qiang; Nakano, Kyoko; Osanai, Tomohiro; Suga, Sechiko; Wakui, Makoto; Wu, Jie

    2008-01-01

    Aim: Hydrogen peroxide (H2O2) is produced during liver transplantation. Ischemia/reperfusion induces oxidation and causes intracellular Ca2+ overload, which harms liver cells. Our goal was to determine the precise mechanisms of these processes. Methods: Hepatocytes were extracted from rats. Intracellular Ca2+ concentrations ([Ca2+]i), inner mitochondrial membrane potentials and NAD(P)H levels were measured using fluorescence imaging. Phospholipase C (PLC) activity was detected using exogenous...

  7. Alkaline peroxide processing of low-enriched uranium targets for 99Mo production -- Decomposition of hydrogen peroxide

    International Nuclear Information System (INIS)

    The recent progress on the alkaline peroxide processing of low-enriched uranium targets for the production of 99Mo, a parent nuclide of the widely used medical isotope 99mTc, is reported. Kinetic studies were undertaken to investigate the decomposition of hydrogen peroxide in alkaline solution in contact with a uranium metal surface. It was found that the decomposition of hydrogen peroxide essentially follows the kinetic trend of uranium dissolution and can be classified into two regimes, depending on the hydroxide concentration. In the low-base regime (0.2 M), the rate of peroxide decomposition is independent of alkali concentration. When the acid/base equilibrium between H2O2 and O2H- is taken into account, the overall rate of hydrogen peroxide disappearance can be described as a 0.25th order reaction with respect to hydrogen peroxide concentration over NaOH concentrations ranging from 0.01 to 5 M. Empirical kinetics models are proposed and discussed

  8. Photoluminescence of MoS2 quantum dots quenched by hydrogen peroxide: A fluorescent sensor for hydrogen peroxide

    Science.gov (United States)

    Gan, Zhixing; Gui, Qingfeng; Shan, Yun; Pan, Pengfei; Zhang, Ning; Zhang, Lifa

    2016-09-01

    By cutting MoS2 microcrystals to quantum dots (QDs) of sizes below 10 nm, the photoluminescence (PL) at ca. 450 nm can be detected easily due to the quantum confinement effects across the 2D planes. The PL is stable under continuous irradiation of UV light but gradually quenches when treated with an increasing concentration of hydrogen peroxide. Time-resolved PL and Raman spectra imply that H2O2 causes the partial oxidation of MoS2 QDs. First-principles calculations reveal that the MoS2 QDs with oxygen impurity are of indirect bandgap structures showing no notable PL. And absorption spectra verify that the PL of MoS2 QDs quenched by H2O2 is attributed to the oxidation. The integrated PL intensity and H2O2 concentration show an exponential relationship in the range of 2-20 μM, suggesting that MoS2 QDs are potential fluorescent probes for hydrogen peroxide sensing in a physiological environment.

  9. Electrocatalysis of hydrogen peroxide reactions on perovskite oxides: experiment versus kinetic modeling.

    Science.gov (United States)

    Poux, T; Bonnefont, A; Ryabova, A; Kéranguéven, G; Tsirlina, G A; Savinova, E R

    2014-07-21

    Hydrogen peroxide has been identified as a stable intermediate of the electrochemical oxygen reduction reaction on various electrodes including metal, metal oxide and carbon materials. In this article we study the hydrogen peroxide oxidation and reduction reactions in alkaline medium using a rotating disc electrode (RDE) method on oxides of the perovskite family (LaCoO3, LaMnO3 and La0.8Sr0.2MnO3) which are considered as promising electrocatalytic materials for the cathode of liquid and solid alkaline fuel cells. The experimental findings, such as the higher activity of Mn-compared to that of Co-perovskites, the shape of RDE curves, and the influence of the H2O2 concentration, are rationalized with the help of a microkinetic model.

  10. Non-enzymatic hydrogen peroxide sensor based on Co3O4 nanocubes

    Indian Academy of Sciences (India)

    Guang Sheng Cao; Lei Wang; Pengfei Yuan; Chao Gao; Xiaojuan Liu; Tong Li; Tianmin Li

    2014-10-01

    The Co3O4 nanocubes were prepared by using hydrogen peroxide (H2O2) as oxidant, Co(NO3)2. 6H2O as a cobalt source. The products were characterized in detail by multiform techniques: scanning electron microscopy (SEM), transmission electron microscopy (TEM) and X-ray diffraction (XRD). The prepared Co3O4 nanocubes were applied to study the electrocatalytic reduction of hydrogen peroxide (H2O2) in 0.01 M pH 7.0 phosphate buffer medium. The Co3O4 nanocubes exhibit remarkable electrocatalytic activity for H2O2 reduction. Furthermore, the obtained Co3O4 nanocubes have been employed as electrode materials for electrochemical sensing H2O2.

  11. Vanadium(5) peroxocomplexes in catalysis of hydrogen peroxide transformations in trifluoroacetic acid

    International Nuclear Information System (INIS)

    It is found that vanadium(5) complexes in trifluoroacetic acid catalyze effectively hydrogen peroxide decomposition with formation of considerable amounts of ozone (up to 15 %). It is also found that vanadium compounds in the course of interaction with peroxytrifluoroacetic acid catalyze not only its decomposition but also decarboxylation. It is ascertained by kinetic methods that in the system V(5)-H2O2-CF3COOH a series of vanadium(5) active complexes, responsible for oxidation of all the compounds studied and ozone evolution, are formed. It is shown that in the formation of the compounds both hydrogen peroxide and peroxytrifluoroacetic acid take part. All the regularities found are explained in the framework of the model, involving intrasphere regrouping of two peroxoligands into grouping (O32-). A mathematical model, which gives an adequate description of substrate oxidation and ozone formation, is plotted

  12. Uranium- and thorium-doped graphene for efficient oxygen and hydrogen peroxide reduction.

    Science.gov (United States)

    Sofer, Zdeněk; Jankovský, Ondřej; Šimek, Petr; Klímová, Kateřina; Macková, Anna; Pumera, Martin

    2014-07-22

    Oxygen reduction and hydrogen peroxide reduction are technologically important reactions in the fields of energy generation and sensing. Metal-doped graphenes, where metal serves as the catalytic center and graphene as the high area conductor, have been used as electrocatalysts for such applications. In this paper, we investigated the use of uranium-graphene and thorium-graphene hybrids prepared by a simple and scalable method. The hybrids were synthesized by the thermal exfoliation of either uranium- or thorium-doped graphene oxide in various atmospheres. The synthesized graphene hybrids were characterized by high-resolution XPS, SEM, SEM-EDS, combustible elemental analysis, and Raman spectroscopy. The influence of dopant and exfoliation atmosphere on electrocatalytic activity was determined by electrochemical measurements. Both hybrids exhibited excellent electrocatalytic properties toward oxygen and hydrogen peroxide reduction, suggesting that actinide-based graphene hybrids have enormous potential for use in energy conversion and sensing devices.

  13. Investigation of Iron Powder, Hydrogen Peroxide and Iron Hydrogen Peroxide for Removal of Acid Yellow Powder 36 Dye from Aqueous Solutions

    OpenAIRE

    Sardar, M.; A Sheikh Mohammadi; A.R Yazdanbakhsh; H Mohammad; M Zarabi

    2010-01-01

    "n "nBackgrounds and Objectives: A great part of organic compounds cause more pollution in natural  waters meet, are chemical dye material. Azo dyes have more usage in different industries. Azo dyes not only give undesirable dye to the water but also have mutation potential and carcinogenesis effects in human and cause the production of toxic substances in water environments.The purpose of this study is investigation of iron powder, hydrogen peroxide and iron powder-hydrogen peroxide pro...

  14. Contact Lens Solutions With Hydrogen Peroxide: To Avoid Injury, Follow All Instructions

    Science.gov (United States)

    ... should never put hydrogen peroxide directly into your eyes or on your contact lenses,” Lepri says. That’s because this kind of solution ... for Solutions With Hydrogen Peroxide Talk to your eye-care provider ... for your contact lenses. Never change your lens-care system before consulting ...

  15. 21 CFR 172.167 - Silver nitrate and hydrogen peroxide solution.

    Science.gov (United States)

    2010-04-01

    ... FOOD FOR HUMAN CONSUMPTION Food Preservatives § 172.167 Silver nitrate and hydrogen peroxide solution... 21 Food and Drugs 3 2010-04-01 2009-04-01 true Silver nitrate and hydrogen peroxide solution. 172.167 Section 172.167 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND...

  16. Tricholoma matsutake fruit bodies secrete hydrogen peroxide as a potent inhibitor of fungal growth.

    Science.gov (United States)

    Takakura, Yoshimitsu

    2015-06-01

    Tricholoma matsutake is an ectomycorrhizal fungus that dominates the microbial communities in the soil of pine and spruce forests. The mycorrhizas of this fungus have antimicrobial activity, although factors responsible for the antimicrobial activity have not been fully elucidated. The present study shows that fruit bodies of T. matsutake secreted hydrogen peroxide (H2O2), which was produced by pyranose oxidase, and that the H2O2 thus secreted strongly inhibited the growth of mycelia of the phytopathological fungus Rhizoctonia solani. These findings suggest that fruit bodies of T. matsutake have antifungal activity and that the pyranose oxidase plays an important role in the antifungal activity. PMID:25803209

  17. Kinetic release of hydrogen peroxide from different whitening products.

    Science.gov (United States)

    da Silva Marques, Duarte Nuno; Silveira, Joao Miguel; Marques, Joana Rita; Amaral, Joao Almeida; Guilherme, Nuno Marques; da Mata, António Duarte

    2012-01-01

    The objective of this in vitro study was to evaluate the kinetics of hydrogen peroxide (HP) release from five different bleaching products: VivaStyle® 10% fitted tray gel, VivaStyle® 30% in-office bleaching gel, VivaStyle® Paint-On Plus paint-on bleaching varnish, Opalescence PF® 10% carbamide peroxide gel and Trèswhite Supreme™ 10% HP gel. Each product was firstly titrated for its HP content by a described method. HP release kinetics was assessed by a modified spectrophotometric technique. One sample t test was performed to test for differences between the manufacturers' claimed HP concentrations and the titrated HP content in the whitening products. Analysis of variance plus Tamhane's post hoc tests and Pearson correlation analysis were used as appropriate. Values of P tested (P tested. These results are consistent with manufacturers' reduced recommended application times. The results of this study suggest that modifying the matrix composition may be a viable alternative to HP concentration increase, since this may result in faster release kinetics without exposure to high HP concentrations. PMID:22908081

  18. Determination of peracetic acid and hydrogen peroxide in the mixture

    Directory of Open Access Journals (Sweden)

    Bodiroga Milanka

    2002-01-01

    Full Text Available Iodometric and permanganometric titrations were used for determination of peracetic acid and hydrogen peroxide (H2O2 in the mixture. Two procedures were described and compared. Titrations could be done in only one vessel, in the same reaction mixture, when iodometric titration of peracetic acid was continued after the permanganometric titration of H2O2, (procedure A. Peracetic acid and H2O2, as oxidizing agents, reacted with potassium iodide in an acid medium, evolving iodine. This reaction was used for the quantitative iodometric determination of total peroxide in procedure B. H2O2 reacted with potassium permanganate in acid medium, but peracetic acid did not react under the same conditions. That made possible the selective permanganometric determination of H2O2 in the presence of peracetic acid. The procedure B was performed in two titration vessels (KV=3.4% for peracetic acid, 0.6% for H2O2. The procedure A for iodometric determination of peracetic acid in one titration vessel after permanganometric titration of H2O2 was recommended (KV=2,5% for peracetic acid, 0,45% for H2O2.

  19. Production of zirconia powders by precipitation stripping with hydrogen peroxide

    International Nuclear Information System (INIS)

    This paper reports on an experimental study to obtain zirconia powders (ZrO2) from carboxylate zirconium solutions followed by hydrogen peroxide stripping and precipitation, that has been carried out. Zirconium carboxylate was prepared by solvent extraction from a chloride aqueous phase using magnesium carboxylate as organic phase. The variables examined in the precipitation were: Temp. 25-90 degrees C, H2O2 concentration: 0.3-5%, pH: 1-9. Organic/Aqueous ration (1/1) and reaction time (30 min.) were maintained at constant levels. The optimum results (98% of precipitation) were achieved at 25 degrees C, 5% H2O2 and pH 5. The precipitates were composed of large amorphous aggregates (2 with large variation of particle size (1-100 μm) was obtained

  20. Gold-catalyzed oxidation of substituted phenols by hydrogen peroxide

    KAUST Repository

    Cheneviere, Yohan

    2010-10-20

    Gold nanoparticles deposited on inorganic supports are efficient catalysts for the oxidation of various substituted phenols (2,6-di-tert-butyl phenol and 2,3,6-trimethyl phenol) with aqueous hydrogen peroxide. By contrast to more conventional catalysts such as Ti-containing mesoporous silicas, which convert phenols to the corresponding benzoquinones, gold nanoparticles are very selective to biaryl compounds (3,3′,5,5′-tetra-tert-butyl diphenoquinone and 2,2′,3,3′,5,5′-hexamethyl-4,4′- biphenol, respectively). Products yields and selectivities depend on the solvent used, the best results being obtained in methanol with yields >98%. Au offers the possibility to completely change the selectivity in the oxidation of substituted phenols and opens interesting perspectives in the clean synthesis of biaryl compounds for pharmaceutical applications. © 2010 Elsevier B.V. All rights reserved.

  1. Spatial and temporal variations and factors controlling the concentrations of hydrogen peroxide and organic peroxides in rivers

    OpenAIRE

    Mostofa, Khan M. G.; Sakugawa, Hiroshi

    2009-01-01

    Hydrogen peroxide (H2O2) and organic peroxides (ROOH) were examined in water samples collected from the upstream and downstream sites of two Japanese rivers (the Kurose and the Ohta). H2O2 concentrations during monthly measurements varied between 6 and 213nM in the Kurose River and 33 and 188nM in the Ohta River. ROOH varied between 0 and 73nM in the Kurose River and 1 and 80nM in the Ohta. Concentrations of peroxides were higher during the summer months than in winter. H2O2 concentrations co...

  2. Development of hydrogen peroxide technique for bioburden reduction

    Science.gov (United States)

    Rohatgi, N.; Schwartz, L.; Stabekis, P.; Barengoltz, J.

    In order to meet the National Aeronautics and Space Administration (NASA) Planetary Protection microbial reduction requirements for Mars in-situ life detection and sample return missions, entire planetary spacecraft (including planetary entry probes and planetary landing capsules) may have to be exposed to a qualified sterilization process. Presently, dry heat is the only NASA approved sterilization technique available for spacecraft application. However, with the increasing use of various man-made materials, highly sophisticated electronic circuit boards, and sensors in a modern spacecraft, compatibility issues may render this process unacceptable to design engineers and thus impractical to achieve terminal sterilization of the entire spacecraft. An alternative vapor phase hydrogen peroxide sterilization process, which is currently used in various industries, has been selected for further development. Strategic Technology Enterprises, Incorporated (STE), a subsidiary of STERIS Corporation, under a contract from the Jet Propulsion Laboratory (JPL) is developing systems and methodologies to decontaminate spacecraft using vaporized hydrogen peroxide (VHP) technology. The VHP technology provides an effective, rapid and low temperature means for inactivation of spores, mycobacteria, fungi, viruses and other microorganisms. The VHP application is a dry process affording excellent material compatibility with many of the components found in spacecraft such as polymers, paints and electronic systems. Furthermore, the VHP process has innocuous residuals as it decomposes to water vapor and oxygen. This paper will discuss the approach that is being used to develop this technique and will present lethality data that have been collected to establish deep vacuum VHP sterilization cycles. In addition, the application of this technique to meet planetary protection requirements will be addressed.

  3. Chemiluminescent Nanomicelles for Imaging Hydrogen Peroxide and Self-Therapy in Photodynamic Therapy

    Directory of Open Access Journals (Sweden)

    Rui Chen

    2011-01-01

    Full Text Available Hydrogen peroxide is a signal molecule of the tumor, and its overproduction makes a higher concentration in tumor tissue compared to normal tissue. Based on the fact that peroxalates can make chemiluminescence with a high efficiency in the presence of hydrogen peroxide, we developed nanomicelles composed of peroxalate ester oligomers and fluorescent dyes, called peroxalate nanomicelles (POMs, which could image hydrogen peroxide with high sensitivity and stability. The potential application of the POMs in photodynamic therapy (PDT for cancer was also investigated. It was found that the PDT-drug-loaded POMs were sensitive to hydrogen peroxide, and the PDT drug could be stimulated by the chemiluminescence from the reaction between POMs and hydrogen peroxide, which carried on a self-therapy of the tumor without the additional laser light resource.

  4. Kinetics of dissolution of uranium metal foil by alkaline hydrogen peroxide

    International Nuclear Information System (INIS)

    To develop a new process for the production of 99Mo using low-enriched uranium targets, uranium dissolution in alkaline hydrogen peroxide was studied. Molybdenum-99 is a parent of the widely used medical isotope 99mTc. The rates of uranium dissolution in alkaline hydrogen peroxide solution were measured in an open, batch-type reactor and were found to be a 0.25th order reaction with respect to equilibrium hydrogen peroxide concentration. In general, uranium dissolution can be classified as a low-base (0.2 M hydroxide) process. In the low-base process, both the equilibrium hydrogen peroxide and the hydroxide concentrations affect the rate of uranium dissolution. In the high-base process, uranium dissolution is independent of alkali concentration; the presence of base affects only the equilibrium concentration of hydrogen peroxide. An empirical kinetics model is proposed and discussed

  5. Amperometric determination of hydrogen peroxide by functionalized carbon nanotubes through EDC/NHS coupling chemistry.

    Science.gov (United States)

    Jeykumari, D R Shobha; Narayanan, S Sriman

    2007-06-01

    The electrochemistry of the redox mediator Toluidine blue (TB) which was covalently linked to the carboxyl group of the multiwalled carbon nanotubes (MWNTs) by coupling reactions, in which N-hydroxysuccinimide was used to assist 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide hydrochloride catalyzed amidation reaction is described. The results from cyclic voltammetry (CV) and amperometry suggested that the redox mediator is linked to the surface of the MWNTs and the nanotubes showed an obvious promotion for the direct electron-transfer between the redox mediator and the electrode. A couple of well-defined redox peak of TB was observed in a phosphate buffer solution (pH 7.0). The redox mediator immobilized to MWNTs exhibits remarkable electrocatalytic activity for the reduction of hydrogen peroxide (H2O2). The analytical applicability of the modified electrode for the determination of hydrogen peroxide was examined. A linear response in the concentration range of 6.8 x 10(-7)-3.4 x 10(-2) M (r = 0.9958) was obtained with detection limit of 3.4 x 10(-7) M for the determination of hydrogen peroxide. The modified electrode has advantages of being highly stable, sensitive, ease of construction and use. PMID:17654948

  6. Inhibition of hydrogen peroxide induced injuring on human skin fibroblast by Ulva prolifera polysaccharide.

    Science.gov (United States)

    Cai, Chuner; Guo, Ziye; Yang, Yayun; Geng, Zhonglei; Tang, Langlang; Zhao, Minglin; Qiu, Yuyan; Chen, Yifan; He, Peimin

    2016-10-01

    Ulva prolifera can protect human skin fibroblast from being injured by hydrogen peroxide. This work studied the composition of Ulva prolifera polysaccharide and identified its physicochemical properties. The results showed that the cell proliferation of 0.5mg/mL crude polysaccharide was 154.4% of that in negative control group. Moreover, ROS detection indices, including DCFH-DA, GSH-PX, MDA and CAT, indicated that crude polysaccharide could improve cellular ability to scavenge free radical and decrease the injury on human skin fibroblast by hydrogen peroxide. In purified polysaccharide, the activity of fraction P1-1 was the highest, with 174.6% of that in negative control group. The average molecular weight of P1-1 was 137kD with 18.0% of sulfate content. This work showed the inhibition of hydrogen peroxide induced injuries on human skin fibroblast by Ulva prolifera polysaccharide, which may further evaluate the application of U. prolifera on cosmetics. PMID:27211299

  7. Photoproduction of hydrogen peroxide in aqueous solution from model compounds for chromophoric dissolved organic matter (CDOM)

    International Nuclear Information System (INIS)

    Highlights: • CDOM produces hydrogen peroxide in sunlit surface waters. • Quinone moieties have been proposed as the photo-active chromophore in CDOM. • Hydrogen peroxide is produced in irradiated aqueous quinone solutions. • Concentrations and production rates are comparable to humic and fulvic acids. • Optical properties post-irradiation were similar to CDOM. - Abstract: To explore whether quinone moieties are important in chromophoric dissolved organic matter (CDOM) photochemistry in natural waters, hydrogen peroxide (H2O2) production and associated optical property changes were measured in aqueous solutions irradiated with a Xenon lamp for CDOM model compounds (dihydroquinone, benzoquinone, anthraquinone, napthoquinone, ubiquinone, humic acid HA, fulvic acid FA). All compounds produced H2O2 with concentrations ranging from 15 to 500 μM. Production rates were higher for HA vs. FA (1.32 vs. 0.176 mM h−1); values ranged from 6.99 to 0.137 mM h−1 for quinones. Apparent quantum yields (Θapp; measure of photochemical production efficiency) were higher for HA vs. FA (0.113 vs. 0.016) and ranged from 0.0018 to 0.083 for quinones. Dihydroquinone, the reduced form of benzoquinone, had a higher production rate and efficiency than its oxidized form. Post-irradiation, quinone compounds had absorption spectra similar to HA and FA and 3D-excitation–emission matrix fluorescence spectra (EEMs) with fluorescent peaks in regions associated with CDOM

  8. Electrodeposition of Silver Nanoparticles on MWCNT Film Electrodes for Hydrogen Peroxide Sensing

    Institute of Scientific and Technical Information of China (English)

    DING,Yan-Feng; JIN,Guan-Ping; YIN,Jun-Guang

    2007-01-01

    Silver (Ag) nanoparticles were directly electrodeposited on multi-walled carbon nanotubes (MWCNT) in AgNO3/LiNO3 containing EDTA (ethylenediaminetetraacetic acid). The structure and nature of the resulting Ag/MWNT composite were characterized by field emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM) and X-ray diffraction (XRD), and the distribution shape of Ag nanoparticles was found to be dependent on the presence of EDTA. The modified electrode showed excellent electrocatalytic activity to redox reaction of hydrogen peroxide and the mechanism of hydrogen peroxide was partly reversible procession with oxidation and reduction peaks at 0.77 and -0.83 V, respectively. The oxidation and reduction peak currents were linearly related to hydrogen peroxide concentration in the range of 1×10-6-3×10-4 and 1×10-8-7×10-4 mol·L-1 with correlation coefficients of 0.996 and 0.986, and 3s-detection limit of 9 × 10-7 and 7 × 10-9 mol·L-1.

  9. Coordinate cis-[Cr(C2O4(pm(OH22]+ Cation as Molecular Biosensor of Pyruvate’s Protective Activity Against Hydrogen Peroxide Mediated Cytotoxity

    Directory of Open Access Journals (Sweden)

    Lech Chmurzyński

    2008-08-01

    Full Text Available In this paper instrumental methods of carbon dioxide (CO2 detection in biological material were compared. Using cis-[Cr(C2O4(pm(OH22]+ cation as a specific molecular biosensor and the stopped-flow technique the concentrations of CO2 released from the cell culture medium as one of final products of pyruvate decomposition caused by hydrogen peroxide were determined. To prove the usefulness of our method of CO2 assessment in the case of biological samples we investigated protective properties of exogenous pyruvate in cultured osteosarcoma 143B cells exposed to 1 mM hydrogen peroxide (H2O2 added directly to culture medium. Pyruvic acid is well known scavenger of H2O2 and, moreover, a molecule which is recognized as one of the major mediator of oxidative stress detected in many diseases and pathological situations like ischemiareperfusion states. The pyruvate's antioxidant activity is described as its rapid reaction with H2O2,which causes nonenzymatic decarboxylation of pyruvate and releases of CO2, water and acetate as final products. In this work for the first time we have correlated the concentration of CO2 dissolved in culture medium with pyruvate's oxidant-scavenging abilities. Moreover, the kinetics of the reaction between aqueous solution of CO2 and coordinate ion, cis-[Cr(C2O4(pm(OH22]+ was analysed. The results obtained enabled determination of the number of steps of the reaction studied. Based on the kinetic equations, rate constants were determined for each step.

  10. SIMULTANEOUS REACTION AND LIQUID-LIQUID EXTRACTION IN THE HYDROGEN PEROXIDE PRODUCTION

    Institute of Scientific and Technical Information of China (English)

    Shuxiang L(u); Li Wang; Zhentao Mi; Yaquan Wang

    2004-01-01

    The gas-liquid-liquid reactive extraction system for preparing hydrogen peroxide via anthraquinone was investigated. The oxidation reaction of hydrogenated working solution was combined with the extraction of hydrogen peroxide from working solution in a sieve plate column. The reaction of 2-ethylanthrahydroquionone with oxygen and the liquid-liquid extraction of hydrogen peroxide take place simultaneously. The oxygen was introduced with hydrogenated working solution through a nozzle in the bottom of the column, which worked as agitated air as well as oxidation reagent. The results showed the oxidation and extraction do not hamper each other, on the contrary, the presence of oxidation gas in the column can promote the transfer of hydrogen peroxide from organic phase to aqueous phase, thus the reaction efficiency and extraction efficiency increased with increasing gas superficial velocity. Furthermore, the oxidation efficiency is almost 100% and the extraction efficiency is higher than 90% in this process.

  11. SIMULTANEOUS REACTION AND LIQUID-LIQUID EXTRACTION IN THE HYDROGEN PEROXIDE PRODUCTION

    Institute of Scientific and Technical Information of China (English)

    ShuxiangLǖ; LiWang; ZhentaoMi; YaquanWang

    2004-01-01

    The gas-liquid-liquid reactive extraction system for preparing hydrogen peroxide via anthraquinone was investigated. The oxidation reaction of hydrogenated working solution was combined with the extraction of hydrogen peroxide from working solution in a sieve plate column. The reaction of 2-ethylanthrahydroquionone with oxygen and the liquid-liquid extraction of hydrogen peroxide take place simultaneously. The oxygen was introduced with hydrogenated working solution through a nozzle in the bottom of the column, which worked as agitated air as well as oxidation reagent. The results showed the oxidation and extraction do not hamper each other, on the contrary, the presence of oxidation gas in the column can promote the transfer of hydrogen peroxide fi'om organic phase to aqueous phase, thus the reaction efficiency and extraction efficiency increased with increasing gas superficial velocity. Furthermore, the oxidation efficiency is almost 100% and the extraction efficiency is higher than 90% in this process.

  12. Core-shell Au/Ag nanoparticles embedded in silicate sol-gel network for sensor application towards hydrogen peroxide

    Indian Academy of Sciences (India)

    Shanmugam Manivannan; Ramasamy Ramaraj

    2009-09-01

    The electrocatalytic activity of core-shell Au100-Ag ( = 15, 27, 46, and 60) bimetallic nanoparticles embedded in methyl functionalized silicate MTMOS network towards the reduction of hydrogen peroxide was investigated by using cyclic voltammetry and chronoamperometric techniques. Core-shell Au/Ag bimetallic nanoparticles were characterized by absorption spectra and HRTEM. The MTMOS silicate sol-gel embedded Au73Ag27 core-shell nanoparticles modified electrode showed better synergistic electrocatalytic effect towards the reduction of hydrogen peroxide when compared to monometal MTMOS-Aunps and MTMOS-Agnps modified electrodes. These modified electrodes were studied without immobilizing any enzyme in the MTMOS sol-gel matrix. The present study highlights the influence of molar composition of Ag nanoparticles in the Au/Ag bimetallic composition towards the electrocatalytic reduction and sensing of hydrogen peroxide in comparison to monometal Au and Ag nanoparticles.

  13. Kinetics of the decomposition and the estimation of the stability of 10% aqueous and non-aqueous hydrogen peroxide solutions

    Directory of Open Access Journals (Sweden)

    Zun Maria

    2014-12-01

    Full Text Available In this study, the stability of 10% hydrogen peroxide aqueous and non-aqueous solutions with the addition of 6% (w/w of urea was evaluated. The solutions were stored at 20°C, 30°C and 40°C, and the decomposition of hydrogen peroxide proceeded according to first-order kinetics. With the addition of the urea in the solutions, the decomposition rate constant increased and the activation energy decreased. The temperature of storage also affected the decomposition of substance, however, 10% hydrogen peroxide solutions prepared in PEG-300, and stabilized with the addition of 6% (w/w of urea had the best constancy.

  14. Protective Effects of Minor Components of Curcuminoids on Hydrogen Peroxide-Treated Human HaCaT Keratinocytes.

    Science.gov (United States)

    Liu, Yuh-Hwa; Lin, Yin-Shiou; Huang, Yu-Wei; Fang, Sheng-Uei; Lin, Shyr-Yi; Hou, Wen-Chi

    2016-05-11

    Hydrogen peroxide, one of the reactive oxygen species (ROS), can cause intracellular oxidative stress associated with skin aging and/or photoaging. Curcumin, a polyphenol in turmeric, has been reported to exhibit biological activity. In this study, five naturally occurring curcuminoids [curcumin, demethoxycurcumin (DMC), bisdemethoxycurcumin (BDMC), monohydroxy-DMC, and monohydroxy-BDMC] were used to investigate their protective roles against hydrogen peroxide-induced oxidative stress in the immortalized human keratinocyte cell lines (HaCaT cells). These five curcuminoids at 10 μM, but not at 5 μM, were shown to exhibit cytotoxicities toward HaCaT keratinocytes. Therefore, a 5 μM concentration of the five curcuminoids was selected for further investigations. Cells were pretreated with or without curcuminoids for 2.5 h before 24-h hydrogen peroxide (150 μM) treatments. Pretreatments with the minor components monohydroxy-DMC or monohydroxy-BDMC, but not curcumin, DMC, and BDMC, showed protective activity, elevating cell viability compared to cells with direct hydrogen peroxide treatments. Pretreatments with monohydroxy-DMC and monohydroxy-BDMC showed the best protective effects, reducing apoptotic cell populations and intracellular ROS, as demonstrated by flow cytometry, as well as reducing the changes of the mitochondrial membrane potential compared to cells with direct hydrogen peroxide treatments. The pretreatments with monohydroxy-DMC and monohydroxy-BDMC reduced c-jun and c-fos mRNA expression and p53 tumor suppressor protein expression and increased HO-1 protein expression and glutathione peroxidase (GPx) activity, respectively, compared to cells with direct hydrogen peroxide treatments. The five curcuminoids exhibited similar hydrogen peroxide-scavenging activity in vitro. It was proposed that monohydroxy-DMC and monohydroxy-BDMC could induce antioxidant defense systems better than curcumin, DMC, or BDMC could against hydrogen peroxide-induced oxidative

  15. Investigation of a novel electrocatalyst for hydrogen peroxide reduction and its application to sensing and biosensing.

    OpenAIRE

    Gonzalez Macia, Laura

    2011-01-01

    Hydrogen peroxide has, for many years, been shown to be a very important compound due to its wide and varied applications in many industrial processes as well as biological systems. Therefore, its detection and measurement represents an important analytical issue. Traditional methods such as titrimetry or spectrophotometry have more recently been displaced by electrochemical techniques, which have proven to be an inexpensive and effective means of hydrogen peroxide determination. Hydrogen ...

  16. Evaluation of Extraradicular Diffusion of Hydrogen Peroxide during Intracoronal Bleaching Using Different Bleaching Agents

    Directory of Open Access Journals (Sweden)

    Mohammad E. Rokaya

    2015-01-01

    Full Text Available Objectives. Extra radicular diffusion of hydrogen peroxide associated with intracoronal teeth bleaching was evaluated. Methods. 108 intact single rooted extracted mandibular first premolars teeth were selected. The teeth were instrumented with WaveOne system and obturated with gutta percha and divided into four groups (n=27 according to the bleaching materials used. Each main group was divided into three subgroups (n=9 according to the time of extra radicular hydrogen peroxide diffusion measurements at 1, 7, and 14 days: group 1 (35% hydrogen peroxide, group 2 (35% carbamide peroxide, group 3 (sodium perborate-30% hydrogen peroxide mixture, and group 4 (sodium perborate-water mixture. Four cemental dentinal defects were prepared just below the CEJ on each root surface. The amount of hydrogen peroxide that leached out was evaluated after 1, 7, and 14 days by spectrophotometer analysis. The results were analyzed using the ANOVA and Tukey’s test. Results. Group 1 showed highest extra radicular diffusion, followed by group 3 and group 2, while group 4 showed the lowest mean extra radicular diffusion. Conclusion. Carbamide peroxide and sodium perborate-water mixture are the most suitable bleaching materials used for internal bleaching due to their low extra radicular diffusion of hydrogen peroxide.

  17. Enhancing activated-peroxide formulations for porous materials :

    Energy Technology Data Exchange (ETDEWEB)

    Krauter, Paula; Tucker, Mark D.; Tezak, Matthew S.; Boucher, Raymond

    2012-12-01

    During an urban wide-area incident involving the release of a biological warfare agent, the recovery/restoration effort will require extensive resources and will tax the current capabilities of the government and private contractors. In fact, resources may be so limited that decontamination by facility owners/occupants may become necessary and a simple decontamination process and material should be available for this use. One potential process for use by facility owners/occupants would be a liquid sporicidal decontaminant, such as pHamended bleach or activated-peroxide, and simple application devices. While pH-amended bleach is currently the recommended low-tech decontamination solution, a less corrosive and toxic decontaminant is desirable. The objective of this project is to provide an operational assessment of an alternative to chlorine bleach for low-tech decontamination applications activated hydrogen peroxide. This report provides the methods and results for activatedperoxide evaluation experiments. The results suggest that the efficacy of an activated-peroxide decontaminant is similar to pH-amended bleach on many common materials.

  18. MODIFIED OPAL:A NOVEL STABILIZER FOR HYDROGEN PEROXIDE BLEACHING OF PULPS

    Institute of Scientific and Technical Information of China (English)

    Xueren Qian; Xianhui An; Wenbo Liu; Gang Yu; Zhanqian Song

    2004-01-01

    The possibility of modified opal as the stabilizer of hydrogen peroxide bleaching was investigated. The results showed that the modified opal in place of sodium silicate as the stabilizer of hydrogen peroxide bleaching is feasible. At the same dosage, above 3% ISO can be increased for both wheat straw pulp and deinked pulp. The stabilizing ability of the modified opal to hydrogen peroxide bleaching of pulp is improved markedly. It is favorable for bleaching to increase temperature and time within a permissive extent. The suitable process conditions are 10% of pulp consistency, 3% of hydrogen peroxide, 1.5% of sodium hydroxide, 3% of the modified opal, 70℃ and 60 min when the modified opal is used as the stabilizer of hydrogen peroxide bleaching. At these conditions, the brightness gain can reach about 16% ISO for wheat straw pulp. In addition, it is favorable for bleaching to add a little magnesium sulfate when the modified opal is used as the stabilizer of hydrogen peroxide bleaching, the brightness of pulp can increase I%ISO if0.05% of magnesium sulfate is added. The cost analysis indicated that the modified opal is superior to sodium silicate as the stabilizer of hydrogen peroxide bleaching in economical aspect and has further the potential of market development.

  19. Hydrogen Peroxide Treatment and the Phenylpropanoid Pathway Precursors Feeding Improve Phenolics and Antioxidant Capacity of Quinoa Sprouts via an Induction of L-Tyrosine and L-Phenylalanine Ammonia-Lyases Activities

    Directory of Open Access Journals (Sweden)

    Michał Świeca

    2016-01-01

    Full Text Available Hydrogen peroxide treatment and the phenylpropanoid pathway precursors feeding affected the antioxidant capacity of quinoa sprouts. Compared to the control, total phenolics content was significantly increased by treatment of control sprouts with 50 mM and 200 mM H2O2—an elevation of about 24% and 28%, respectively. The highest increase of flavonoids content was found for the sprouts treated with 200 mM H2O2 obtained from seeds fed with shikimic acid. All the studied modifications increased the antioxidant potential of sprouts (at least by 50% compared to control. The highest reducing power was found for the sprouts treated with 200 mM H2O2 obtained by phenylalanine feeding (5.03 mg TE/g DW and those obtained from the seeds fed with tyrosine (5.26 mg TE/g DW. The activities of L-tyrosine (TAL and L-phenylalanine (PAL ammonia-lyases were strongly affected by germination time as well as the applied modification of sprouting. On the 3rd day the highest PAL activity was determined for both untreated and induced with 50 mM H2O2 sprouts obtained by phenylalanine feeding. H2O2 induced TAL activity; the highest TAL activity was determined for 3-day-old sprouts induced with 200 mM H2O2 obtained from seeds fed with phenylalanine.

  20. Hydrogen peroxide in exhaled breath condensate: A clinical study

    Directory of Open Access Journals (Sweden)

    C Nagaraja

    2012-01-01

    Full Text Available Objectives: To study the ongoing inflammatory process of lung in healthy individuals with risk factors and comparing with that of a known diseased condition. To study the inflammatory response to treatment. Background: Morbidity and mortality of respiratory diseases are raising in trend due to increased smokers, urbanization and air pollution, the diagnosis of these conditions during early stage and management can improve patient′s lifestyle and morbidity. Materials and Methods: One hundred subjects were studied from July 2010 to September 2010; the level of hydrogen peroxide concentration in exhaled breath condensate was measured using Ecocheck. Results: Of the 100 subjects studied, 23 were healthy individuals with risk factors (smoking, exposure to air pollution, and urbanization; the values of hydrogen peroxide in smokers were 200-2220 nmol/l and in non-smokers 340-760 nmol/l. In people residing in rural areas values were 20-140 nmol/l in non-smokers and 180 nmol/l in smokers. In chronic obstructive pulmonary disease cases, during acute exacerbations values were 540-3040 nmol/l and 240-480 nmol/l following treatment. In acute exacerbations of bronchial asthma, values were 400-1140 nmol/l and 100-320 nmol/l following treatment. In cases of bronchiectasis, values were 300-340 nmol/l and 200-280 nmol/l following treatment. In diagnosed pneumonia cases values were 1060-11800 nmol/l and 540-700 nmol/l following treatment. In interstitial lung diseases, values ranged from 220-720 nmol/l and 210-510 nmol/l following treatment. Conclusion: Exhaled breath condensate provides a non-invasive means of sampling the lower respiratory tract. Collection of exhaled breath condensate might be useful to detect the oxidative destruction of the lung as well as early inflammation of the airways in a healthy individual with risk factors and comparing the inflammatory response to treatment.

  1. Hydrogen peroxide induce modifications of human extracellular superoxide dismutase that results in enzyme inhibition

    Directory of Open Access Journals (Sweden)

    Randi H. Gottfredsen

    2013-01-01

    Full Text Available Superoxide dismutase (EC-SOD controls the level of superoxide in the extracellular space by catalyzing the dismutation of superoxide into hydrogen peroxide and molecular oxygen. In addition, the enzyme reacts with hydrogen peroxide in a peroxidase reaction which is known to disrupt enzymatic activity. Here, we show that the peroxidase reaction supports a site-specific bond cleavage. Analyses by peptide mapping and mass spectrometry shows that oxidation of Pro112 supports the cleavage of the Pro112–His113 peptide bond. Substitution of Ala for Pro112 did not inhibit fragmentation, indicating that the oxidative fragmentation at this position is dictated by spatial organization and not by side-chain specificity. The major part of EC-SOD inhibited by the peroxidase reaction was not fragmented but found to encompass oxidations of histidine residues involved in the coordination of copper (His98 and His163. These oxidations are likely to support the dissociation of copper from the active site and thus loss of enzymatic activity. Homologous modifications have also been described for the intracellular isozyme, Cu/Zn-SOD, reflecting the almost identical structures of the active site within these enzymes. We speculate that the inactivation of EC-SOD by peroxidase activity plays a role in regulating SOD activity in vivo, as even low levels of superoxide will allow for the peroxidase reaction to occur.

  2. Hydrogen peroxide produced by oral Streptococci induces macrophage cell death.

    Directory of Open Access Journals (Sweden)

    Nobuo Okahashi

    Full Text Available Hydrogen peroxide (H2O2 produced by members of the mitis group of oral streptococci plays important roles in microbial communities such as oral biofilms. Although the cytotoxicity of H2O2 has been widely recognized, the effects of H2O2 produced by oral streptococci on host defense systems remain unknown. In the present study, we investigated the effect of H2O2 produced by Streptococcus oralis on human macrophage cell death. Infection by S. oralis was found to stimulate cell death of a THP-1 human macrophage cell line at multiplicities of infection greater than 100. Catalase, an enzyme that catalyzes the decomposition of H2O2, inhibited the cytotoxic effect of S. oralis. S. oralis deletion mutants lacking the spxB gene, which encodes pyruvate oxidase, and are therefore deficient in H2O2 production, showed reduced cytotoxicity toward THP-1 macrophages. Furthermore, H2O2 alone was capable of inducing cell death. The cytotoxic effect seemed to be independent of inflammatory responses, because H2O2 was not a potent stimulator of tumor necrosis factor-α production in macrophages. These results indicate that streptococcal H2O2 plays a role as a cytotoxin, and is implicated in the cell death of infected human macrophages.

  3. Specific aquaporins facilitate the diffusion of hydrogen peroxide across membranes.

    Science.gov (United States)

    Bienert, Gerd P; Møller, Anders L B; Kristiansen, Kim A; Schulz, Alexander; Møller, Ian M; Schjoerring, Jan K; Jahn, Thomas P

    2007-01-12

    The metabolism of aerobic organisms continuously produces reactive oxygen species. Although potentially toxic, these compounds also function in signaling. One important feature of signaling compounds is their ability to move between different compartments, e.g. to cross membranes. Here we present evidence that aquaporins can channel hydrogen peroxide (H2O2). Twenty-four aquaporins from plants and mammals were screened in five yeast strains differing in sensitivity toward oxidative stress. Expression of human AQP8 and plant Arabidopsis TIP1;1 and TIP1;2 in yeast decreased growth and survival in the presence of H2O2. Further evidence for aquaporin-mediated H2O2 diffusion was obtained by a fluorescence assay with intact yeast cells using an intracellular reactive oxygen species-sensitive fluorescent dye. Application of silver ions (Ag+), which block aquaporin-mediated water diffusion in a fast kinetics swelling assay, also reversed both the aquaporin-dependent growth repression and the H2O2-induced fluorescence. Our results present the first molecular genetic evidence for the diffusion of H2O2 through specific members of the aquaporin family.

  4. Electrochemical reduction of hydrogen peroxide on stainless steel

    Indian Academy of Sciences (India)

    S Patra; N Munichandraiah

    2009-09-01

    Electrochemical reduction of hydrogen peroxide is studied on a sand-blasted stainless steel (SSS) electrode in an aqueous solution of NaClO4. The cyclic voltammetric reduction of H2O2 at low concentrations is characterized by a cathodic peak at -0.40 V versus standard calomel electrode (SCE). Cyclic voltammetry is studied by varying the concentration of H2O2 in the range from 0.2 mM to 20 mM and the sweep rate in the range from 2 to 100 mV s-1. Voltammograms at concentrations of H2O2 higher than 2 mM or at high sweep rates consist of an additional current peak, which may be due to the reduction of adsorbed species formed during the reduction of H2O2. Amperometric determination of H2O2 at -0.50 V vs SCE provides the detection limit of 5 M H2O2. A plot of current density versus concentration has two segments suggesting a change in the mechanism of H2O2 reduction at concentrations of H2O2 ≥ 2 mM. From the rotating disc electrode study, diffusion co-efficient of H2O2 and rate constant for reduction of H2O2 are evaluated.

  5. Preliminary flight test of hydrogen peroxide retro-propulsion module

    Science.gov (United States)

    An, Sungyong; Jo, Sungkwon; Wee, Jeonghyun; Yoon, Hosung; Kwon, Sejin

    2010-09-01

    In this paper, we present the development of a retro-thruster, the design of a retro-propulsion module, and a preliminary flight of the module in a landing demonstration. First, a retro-monopropellant thruster with the maximum thrust of 350 N that employs hydrogen peroxide as a monopropellant was developed. It's thrust force, efficiency of characteristic velocity, and specific impulse were evaluated during the course of it's development. To control the thrust force, two solenoid valves and a pulse width modulation (PWM) flow control valve were incorporated into the thruster design. Second, a retro-propulsion module with a wet mass of 23 kg was designed and fabricated. All the required components including tanks, propellant tubes, a pressure regulator, valves, a retro-thruster, and support structure were integrated into the module. Finally, a preliminary flight test with thrust and altitude control was carried out successfully. In this test, the throttling of the thrust force and altitude control was performed manually for safety purposes.

  6. Mobile gene silencing in Arabidopsis is regulated by hydrogen peroxide

    Directory of Open Access Journals (Sweden)

    Dacheng Liang

    2014-12-01

    Full Text Available In plants and nematodes, RNAi can spread from cells from which it is initiated to other cells in the organism. The underlying mechanism controlling the mobility of RNAi signals is not known, especially in the case of plants. A genetic screen designed to recover plants impaired in the movement but not the production or effectiveness of the RNAi signal identified RCI3, which encodes a hydrogen peroxide (H2O2-producing type III peroxidase, as a key regulator of silencing mobility in Arabidopsis thaliana. Silencing initiated in the roots of rci3 plants failed to spread into leaf tissue or floral tissue. Application of exogenous H2O2 reinstated the spread in rci3 plants and accelerated it in wild-type plants. The addition of catalase or MnO2, which breaks down H2O2, slowed the spread of silencing in wild-type plants. We propose that endogenous H2O2, under the control of peroxidases, regulates the spread of gene silencing by altering plasmodesmata permeability through remodelling of local cell wall structure, and may play a role in regulating systemic viral defence.

  7. Simultaneous electroanalysis of peroxyacetic acid and hydrogen peroxide.

    Science.gov (United States)

    Awad, M I; Harnoode, C; Tokuda, K; Ohsaka, T

    2001-04-15

    The electrochemical behavior of peroxyacetic acid (PAA) in the presence of hydrogen peroxide (H2O2) has been investigated using cyclic voltammetry and hydrodynamic techniques [rotating disk electrode (RDE) voltammetry and rotating ring-disk electrode (RRDE) voltammetry]. The results have been analyzed aiming at simultaneous electroanalysis of both species. Glassy carbon and gold electrodes were used for this investigation. It was found that the reduction of PAA, as well as H2O2, is highly sensitive to the electrode material; for example, at 100 mV s-1, the reduction peak potentials of PAA were 0.2 and -1.1 V at gold and glassy carbon electrodes, respectively. The well-separated steady-state limiting currents were obtained using a gold electrode for the reduction of both PAA and H2O2 and also a well-defined one for the oxidation of H2O2. On the basis of the RDE experiments, good calibration curves were obtained for both species over a wide range of their concentrations, for PAA and H2O2 in the range of 0.36 to 110 and 0.11 to 34 mM, respectively. The simultaneous and selective electroanalysis of PAA and H2O2 in their coexistence is demonstrated for the first time.

  8. Optimization of Hydrogen Peroxide Detection for a Methyl Mercaptan Biosensor

    Directory of Open Access Journals (Sweden)

    Shi-Gang Sun

    2013-04-01

    Full Text Available Several kinds of modified carbon screen printed electrodes (CSPEs for amperometric detection of hydrogen peroxide (H2O2 are presented in order to propose a methyl mercaptan (MM biosensor. Unmodified, carbon nanotubes (CNTs, cobalt phthalocyanine (CoPC, Prussian blue (PB, and Os-wired HRP modified CSPE sensors were fabricated and tested to detect H2O2, applying a potential of +0.6 V, +0.6 V, +0.4 V, −0.2 V and −0.1 V (versus Ag/AgCl, respectively. The limits of detection of these electrodes for H2O2 were 3.1 μM, 1.3 μM, 71 nM, 1.3 μM, 13.7 nM, respectively. The results demonstrated that the Os-wired HRP modified CSPEs gives the lowest limit of detection (LOD for H2O2 at a working potential as low as −0.1 V. Os-wired HRP is the optimum choice for establishment of a MM biosensor and gives a detection limit of 0.5 μM.

  9. Solvothermal method to prepare graphene quantum dots by hydrogen peroxide

    Science.gov (United States)

    Tian, Renbing; Zhong, Suting; Wu, Juan; Jiang, Wei; Shen, Yewen; Jiang, Wei; Wang, Tianhe

    2016-10-01

    Graphene quantum dots (GQDs) have been synthesized by different chemical methods in recent years. For conventional chemical methods, it is inevitable to introduce a large amount of impurities in the preparation process. Long time of dialysis process increases the time cost extremely. Herein, we report a one-step solvothermal method for synthesizing GQDs with the application of hydrogen peroxide in N, N-Dimethylformamide (DMF) environment, which completely avoids the use of concentrated sulphuric acid and nitric acid to treat raw material and introduces no impurity in whole preparation process simultaneously for the first time. Pure GQDs can be obtained after evaporation/redissolution and filtration process with a strong blue emission at 15% quantum yield. This solvothermal method, not requiring dialysis process and complicated equipments, exhibits simple, eco-friendly and low time-cost properties. Besides high quantum yields, the as-prepared GQDs also show good photoluminescence stability in different pH conditions. The optical properties, morphology and structure of GQDs were studied by various equipments, implying potential application in biomedical fields and electronic device.

  10. Repetitive Peroxide Exposure Reveals Pleiotropic Mitogen-Activated Protein Kinase Signaling Mechanisms

    Directory of Open Access Journals (Sweden)

    Wayne Chadwick

    2011-01-01

    Full Text Available Oxidative stressors such as hydrogen peroxide control the activation of many interconnected signaling systems and are implicated in neurodegenerative disease etiology. Application of hydrogen peroxide to PC12 cells activated multiple tyrosine kinases (c-Src, epidermal growth factor receptor (EGFR, and Pyk2 and the serine-threonine kinase ERK1/2. Peroxide-induced ERK1/2 activation was sensitive to intracellular calcium chelation and EGFR and c-Src kinase inhibition. Acute application and removal of peroxide allowed ERK1/2 activity levels to rapidly subside to basal serum-deprived levels. Using this protocol, we demonstrated that ERK1/2 activation tachyphylaxis developed upon repeated peroxide exposures. This tachyphylaxis was independent of c-Src/Pyk2 tyrosine phosphorylation but was associated with a progressive reduction of peroxide-induced EGFR tyrosine phosphorylation, EGFR interaction with growth factor receptor binding protein 2, and a redistribution of EGFR from the plasma membrane to the cytoplasm. Our data indicates that components of peroxide-induced ERK1/2 cascades are differentially affected by repeated exposures, indicating that oxidative signaling may be contextually variable.

  11. Green tea polyphenols protect spinal cord neurons against hydrogen peroxide-induced oxidative stress

    Institute of Scientific and Technical Information of China (English)

    Jianbo Zhao; Shiqiang Fang; Yajiang Yuan; Zhanpeng Guo; Jinhao Zeng; Yue Guo; Peifu Tang; Xifan Mei

    2014-01-01

    Green tea polyphenols are strong antioxidants and can reduce free radical damage. To investigate their neuroprotective potential, we induced oxidative damage in spinal cord neurons using hy-drogen peroxide, and applied different concentrations (50-200 µg/mL) of green tea polyphenol to the cell medium for 24 hours. Measurements of superoxide dismutase activity, malondial-dehyde content, and expression of apoptosis-related genes and proteins revealed that green tea polyphenol effectively alleviated oxidative stress. Our results indicate that green tea polyphenols play a protective role in spinal cord neurons under oxidative stress.

  12. 8-Alkylcoumarins from the Fruits of Cnidium monnieri Protect against Hydrogen Peroxide Induced Oxidative Stress Damage

    Directory of Open Access Journals (Sweden)

    Chi-I Chang

    2014-03-01

    Full Text Available Three new 8-alkylcoumarins, 7-O-methylphellodenol-B (1, 7-methoxy-8-(3-methyl- 2,3-epoxy-1-oxobutylchromen-2-one (2, and 3'-O-methylvaginol (3, together with seven known compounds (4–10 were isolated from the fruits of Cnidium monnieri. Their structures were determined by detailed analysis of spectroscopic data and comparison with the data of known analogues. All the isolates were evaluated the cytoprotective activity by MTS cell proliferation assay and the results showed that all the three new 8-alkylcoumarins exhibited cytoprotective effect on Neuro-2a neuroblastoma cells injured by hydrogen peroxide.

  13. Activation of Hydrogen Peroxide by Iron-Containing Minerals and Catalysts in Circumneutral pH Solutions: Implications for ex situ and in situ Treatment of Contaminated Water and Soil

    OpenAIRE

    Pham, Anh

    2012-01-01

    The decomposition of hydrogen peroxide (H2O2) on iron minerals can generate hydroxyl radical (*OH), a strong oxidant capable of transforming a wide range of contaminants. This reaction is critical to ex situ advanced oxidation processes employed in waste treatment systems, as well as in situ chemical oxidation processes used for soil and groundwater remediation. Unfortunately, the process in the ex situ treatment systems is relatively inefficient at circumneutral pH values. In this research, ...

  14. Protection of Salvianolic Acid B for Human Endothelial Cells Against Hydrogen Peroxide-Induced Oxidative Damage

    Institute of Scientific and Technical Information of China (English)

    ZHANG Jungang; ZHAO Guangrong; LIU Jinling; JI Xiangwu

    2009-01-01

    Salvianolic acid B(Sal B) is an active component of traditional Chinese medicine Salvia miltiorrhiza and is used to treat vascular diseases. To better understand its mechanism, the antioxidant capacities of Sal B was evaluated with human endothelial cells under oxidative stress. Human endothelial cells were pretreated with Sal B for 12 h followed by hydrogen peroxide for another 12 h. Production of reactive oxygen species (ROS), activities of superoxide dismutase (SOD), catalase (CAT) and glutathione peroxidase (GPX), and concentration of glu-tathione were measured: Protective effect of Sal B on the endothelial cells from hydrogen peroxide-induced damage ' was observed, and ROS production in the cells was found significantly inhibited. Sal B remarkably enhanced the activities of antioxidant enzymes SOD, CAT and GPX. Furthermore, Sal B up-regulated the intracellular glutathione concentration. The results indicate that Sal B protected endothelial cells from oxidative stress by improving the redox status of the cells through enhancing the antioxidant enzyme activities and increasing the reductive glutathione concentration after the oxidative challenge.

  15. Oxidative aromatization of Hantzsch 1,4-dihydropyridines by aqueous hydrogen peroxide-acetic acid

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    A simple method for the oxidative aromatization of Hantzsch 1,4-dihydropyridines to the corresponding pyridines is achieved by using hydrogen peroxide as green oxidant and acetic acid as catalyst in aqueous solution.

  16. MICROWAVE-EXPEDITED OLEFIN EPOXIDATION OVER HYDROTALCITES USING HYDROGEN PEROXIDE AND ACETONITRILE

    Science.gov (United States)

    An efficient microwave-assisted expoxidation of olefins is described over hydrotalcite catalysts in the presence of hydrogen peroxide and acetonitrile. This general and selective protocol is extremely fast and is applicable to a wide variety of subtrates.

  17. Orange II removal by catalytic wet peroxide oxidation using activated carbon xerogels

    OpenAIRE

    Pinho, Maria; Silva, Adrián; Fathy, Nady; Attia, Amina; Gomes, Helder; Faria, Joaquim

    2013-01-01

    Orange II is a synthetic dye widely employed in the textile industry and responsible for serious environrnentaI cancerns. Dyes like this urge the development af new technologies for the treatment af wastewaters generated in this industrial activity. Those include catalytic wet peroxide oxidation (CWPO), which is an advanced oxidation process (AOP) based on the generation of hydroxyl radicais (I-lO·) from hydrogen peroxide with tlle aid ofa suitable catalysl [I].

  18. Hydrogen peroxide inhibits transforming growth factor-β1-induced cell cycle arrest by promoting Smad3 linker phosphorylation through activation of Akt-ERK1/2-linked signaling pathway.

    Science.gov (United States)

    Choi, Jiyeon; Park, Seong Ji; Jo, Eun Ji; Lee, Hui-Young; Hong, Suntaek; Kim, Seong-Jin; Kim, Byung-Chul

    2013-06-14

    Hydrogen peroxide (H2O2) functions as a second messenger in growth factor receptor-mediated intracellular signaling cascade and is tumorigenic by virtue of its ability to promote cell proliferation; however, the mechanisms underlying the growth stimulatory action of H2O2 are less understood. Here we report an important mechanism for antagonistic effects of H2O2 on growth inhibitory response to transforming growth factor-β1 (TGF-β1). In Mv1Lu and HepG2 cells, pretreatment of H2O2 (0.05-0.2 mM) completely blocked TGF-β1-mediated induction of p15(INK4B) expression and increase of its promoter activity. Interestingly, H2O2 selectively suppressed the transcriptional activation potential of Smad3, not Smad2, in the absence of effects on TGF-β1-induced phosphorylation of the COOH-tail SSXS motif of Smad3 and its nuclear translocation. Mechanism studies showed that H2O2 increases the phosphorylation of Smad3 at the middle linker region in a concentration- and time-dependent manner and this effect is mediated by activation of extracellular signal-activated kinase 1/2 through Akt. Furthermore, expression of a mutant Smad3 in which linker phosphorylation sites were ablated significantly abrogated the inhibitory effects of H2O2 on TGF-β1-induced increase of p15(INK4B)-Luc reporter activity and blockade of cell cycle progression from G1 to S phase. These findings for the first time define H2O2 as a signaling molecule that modulate Smad3 linker phosphorylation and its transcriptional activity, thus providing a potential mechanism whereby H2O2 antagonizes the cytostatic function of TGF-β1.

  19. The contribution of rainwater to variability in surface ocean hydrogen peroxide

    OpenAIRE

    Cooper, William J.; SALTZMAN, ERIC S.; Zika, Rod G

    1987-01-01

    Hydrogen peroxide concentrations have been determined in marine rain from the Gulf of Mexico, the western Atlantic Ocean, and one rain event off the Florida Keys. In several cases, simultaneous measurements of the concentration of H2O2 in the surface ocean were also determined. These measurements were made with the ship under way using a continuous flow sampling system with the intake at the bow. In shallow stratified layers, rain events can increase the existing hydrogen peroxide concentrati...

  20. The application of catalase for the elimination of hydrogen peroxide residues after bleaching of cotton fabrics

    Directory of Open Access Journals (Sweden)

    AMORIM ALEXANDRA M.

    2002-01-01

    Full Text Available Results of dyeing of cotton fabrics with a bifunctional reactive dye were significantly improved when the fabric after bleaching with hydrogen peroxide was treated with catalase for the elimination of hydrogen peroxide residues from the fabrics. Compared to processes with a varying number of washing steps, with and without commercial reducing agents, the consumption of water could be significantly reduced, without altering the final color shade.

  1. Natural manganese deposits as catalyst for decomposing hydrogen peroxide (discussion paper)

    OpenAIRE

    Knol, A.H.; Lekkerkerker-Teunissen, K.; Van Dijk, J. C.

    2015-01-01

    Drinking water companies more and more implement Advanced Oxidation Processes (AOP) in their treatment schemes to increase the barrier against organic micropollutants (OMPs). It is necessary to decompose the excessive hydrogen peroxide after applying AOP to avoid negative effects in the following, often biological, treatment steps. A drinking water company in the western part of the Netherlands investigated decomposition of about 5.75 mg L−1 hydrogen peroxide in pre-treated Meuse river water ...

  2. Oxidation of PAHs in water solutions by ultraviolet radiation combined with hydrogen peroxide

    OpenAIRE

    Dorota Olejnik; Jacek S. Miller; Stanisław Ledakowicz

    1999-01-01

    The destruction of three polycyclic aromatic hydrocarbons (PAHs): benzo[a]pyrene, chrysene and fluorene in aqueous solution using advanced oxidation process H2O2/UV was investigated. The influence of pH, initial hydrogen peroxide and radical scavenger concentrations on the reaction rate was studied. The oxidation reactions most rapidly run in neutral and acidic solution at optimal hydrogen peroxide concentration (ca. 0.01 M). The degradation of benzo[a]pyrene and chrysene follows radical reac...

  3. Measurements of the partitioning of hydrogen peroxide in a stratiform cloud

    OpenAIRE

    Noone, Kevin J.; OGREN, JOHN A.; NOONE, K. BIRGITTA; HALLBERG, ANNELI; Fuzzi, Sandro; Lind, John A.

    2011-01-01

    Simultaneous measurements of hydrogen peroxide in cloud droplets and in the air in which the droplets were suspended are presented. In addition, a description of the new technique used to make the measurements is also presented. The ratio of the measured cloudwater concentration to the equilibrium cloudwater concentration predicted using Henry's law and the measured gas-phase hydrogen peroxide was 0.64 (S.D = 0.32, n= 74). Analysis of both random and potential systematic errors indicate that ...

  4. Boronate-based fluorescent probes: imaging hydrogen peroxide in living systems.

    Science.gov (United States)

    Lin, Vivian S; Dickinson, Bryan C; Chang, Christopher J

    2013-01-01

    Hydrogen peroxide, a reactive oxygen species with unique chemical properties, is produced endogenously in living systems as a destructive oxidant to ward off pathogens or as a finely tuned second messenger in dynamic cellular signaling pathways. In order to understand the complex roles that hydrogen peroxide can play in biological systems, new tools to monitor hydrogen peroxide in its native settings, with high selectivity and sensitivity, are needed. Knowledge of organic synthetic reactivity provides the foundation for the molecular design of selective, functional hydrogen peroxide probes. A palette of fluorescent and luminescent probes that react chemoselectively with hydrogen peroxide has been developed, utilizing a boronate oxidation trigger. These indicators offer a variety of colors and in cellulo characteristics and have been used to examine hydrogen peroxide in a number of experimental setups, including in vitro fluorometry, confocal fluorescence microscopy, and flow cytometry. In this chapter, we provide an overview of the chemical features of these probes and information on their behavior to help researchers select the optimal probe and application.

  5. Isothermal Microcalorimetric Evaluation of Compatibility of Proposed Injector Materials with High-Test Hydrogen Peroxide Propellant

    Science.gov (United States)

    Gostowski, Rudy

    2003-01-01

    High-test hydrogen peroxide (HTP) is receiving renewed interest as a monopropellant and as the oxidizer for bipropellant systems. HTP is hydrogen peroxide in concentrations ranging from 70 to 98%. All surfaces wetted by HTP must be evaluated for compatibility with the fluid. In the case of tanks, lines and valves compatibility is required to preserve the HTP oxygen and energy content and to avoid overpressurization due to decomposition. With injectors and regenerative cooling passages shorter exposure time reduces these concerns. However, phase changes from fluid to gas impact heat transfer and become the dominant compatibility concern. Isothermal microcalorimetry (IMC) provides a convenient and reproducible means to observe the decomposition of HTP when exposed to structural materials and therefore the compatibility of those materials'. The instrument provides heat flow values in terms of watts that may be converted to a reaction rate given the heat of reaction for the decomposition of hydrogen peroxide. These values are then converted to percent active oxygen loss per week (%AOL/wk) to preserve an earlier convention for quantifying HTP compatibility. Additionally, qualitative designations of compatibility have been assigned to these values. This scheme consists of four classes with Class 1 being the most compatible. While historical compatibility data is available its current applicability is in question due to subtle changes in the compositions of both HTP and structural materials. Trace levels of molecules can have significant influence on compatibility. Therefore representative samples of materials must be evaluated with current HTP formulations. In this work seven materials were selected for their strength characteristics at high temperature as expected in a HTP injector. The materials were then evaluated by IMC for HTP compatibility.

  6. Shock initiation studies on high concentration hydrogen peroxide

    Energy Technology Data Exchange (ETDEWEB)

    Sheffield, Stephen A [Los Alamos National Laboratory; Dattelbaum, Dana M [Los Alamos National Laboratory; Stahl, David B [Los Alamos National Laboratory; Gibson, L. Lee [Los Alamos National Laboratory; Bartram, Brian D. [Los Alamos National Laboratory

    2009-01-01

    Concentrated hydrogen peroxide (H{sub 2}O{sub 2}) has been known to detonate for many years. However, because of its reactivity and the difficulty in handling and confining it, along with the large critical diameter, few studies providing basic information about the initiation and detonation properties have been published. We are conducting a study to understand and quantify the initiation and detonation properties of highly concentrated H{sub 2}O{sub 2} using a gas-driven two-stage gun to produce well defined shock inputs. Multiple magnetic gauges are used to make in-situ measurements of the growth of reaction and subsequent detonation in the liquid. These experiments are designed to be one-dimensional to eliminate any difficulties that might be encountered with large critical diameters. Because of the concern of the reactivity of the H{sub 2}O{sub 2} with the confining materials, a remote loading system has been developed. The gun is pressurized, then the cell is filled and the experiment shot within less than three minutes. TV cameras are attached to the target so the cell filling can be monitored. Several experiments have been completed on {approx}98 wt % H{sub 2}O{sub 2}/H{sub 2}O mixtures; initiation has been observed in some experiments that shows homogeneous shock initiation behavior. The initial shock pressurizes and heats the mixture. After an induction time, a thermal explosion type reaction produces an evolving reactive wave that strengthens and eventually overdrives the first wave producing a detonation. From these measurements, we have determined unreacted Hugoniot information, times (distances) to detonation (Pop-plot points) that indicate low sensitivity, and detonation velocities of high concentration H{sub 2}O{sub 2}/H{sub 2}O solutions that agree with earlier estimates.

  7. Processing of LEU targets for 99Mo production - Dissolution of metal foil targets by alkaline hydrogen peroxide

    International Nuclear Information System (INIS)

    In FY 1995, we started studies on a new process for dissolution of low-enriched uranium (LEU) targets for 99Mo production. In this process, an LEU metal foil target is dissolved in a mixture of sodium hydroxide and hydrogen peroxide, then 99Mo is recovered from the dissolved solution. We focused on the dissolution kinetics to develop a mechanistic model for predicting the products and the rate of uranium dissolution under process conditions. We thoroughly studied the effects of hydrogen peroxide concentration, sodium hydroxide concentration, and temperature on the rate of uranium dissolution. It was found that uranium dissolution can be classified into a low-base (0.2M) process. In the low-base process, both the equilibrium hydrogen peroxide and hydroxide concentrations affect the rate of uranium dissolution; in the high base process, uranium dissolution is a 0.25th order reaction with respect to the equilibrium hydrogen peroxide. The dissolution activation energy was experimentally determined to be 48.8 kJ/mol. Generally, the rate of uranium dissolution increases to a maximum as the hydroxide concentration is increased from 0.01 to about 1.5M, then it decreases as the hydroxide concentration is further increased. The alkalinity of the dissolution solution is an important factor that affects not only the dissolution rate, but also the amount of radioactive waste. (author)

  8. White tea (Camellia sinensis Kuntze) exerts neuroprotection against hydrogen peroxide-induced toxicity in PC12 cells.

    Science.gov (United States)

    López, Víctor; Calvo, Maria Isabel

    2011-03-01

    Tea is a popular beverage whose consumption is associated with prevention of certain disorders. The objective of the study was to investigate the potential neuroprotective effect of white tea extract (WTE) on hydrogen peroxide induced toxicity in PC12 cells. Cells were treated with various doses of WTE (10-250 μg/ml) before exposition to 250 μM hydrogen peroxide and cell survival was determined through the MTT and LDH assays. Oxidative stress was quantified in the cells after treatments as intracellular reactive oxygen species (ROS) production and the antioxidant activity of the extract was assessed in a cell free system in terms of free radical scavenging capacity. Results showed that WTE has a significant protective effect in the PC12 cell line against hydrogen peroxide as cell survival was significantly superior in WTE-treated cells compared to hydrogen peroxide-treated cells. A reduction on intracellular oxidative stress as well as radical scavenging properties were produced by WTE. Results suggest that WTE protects PC12 cells against H(2)O(2)-induced toxicity, and that an antioxidant mechanism through ROS scavenging may be in part responsible for cells neuroprotection. PMID:21271291

  9. Bactericidal activity of metal-mediated peroxide-ascorbate systems.

    Science.gov (United States)

    Drath, D B; Karnovsky, M L

    1974-11-01

    Model systems containing ascorbate, hydrogen peroxide, and divalent copper or cobalt have been shown to possess marked bactericidal activity. At equivalent concentrations, copper-containing systems were more bactericidal than the corresponding mixtures containing cobalt. Cobalt at concentrations below 10(-4) M did not appreciably augment microbicidal activity, whereas systems containing copper at concentrations as low as 5 x 10(-6) M were still capable of causing some bacterial death. Manganese was inactive. None of these systems was as potent as the well known myeloperoxidase-peroxide-halide system. The mechanisms of action of these systems are not as yet clear. The possibility that they function through the generation of superoxide (O(2) (-)), hydroxyl radical (OH.), or other free radicals was explored through the use of superoxide dismutase and several free radical scavengers. It seems likely at present that the two active metal-mediated systems function via separate mechanisms. The copper system acts with dehydroascorbate, whereas the cobalt system does not. Activity in the cobalt system appears to depend upon the generation of free radicals. PMID:16558093

  10. Three-dimensional electrode microbial fuel cell for hydrogen peroxide synthesis coupled to wastewater treatment

    Science.gov (United States)

    Chen, Jia-yi; Li, Nan; Zhao, Lin

    2014-05-01

    A three-dimensional electrode bioelectrochemical system for the cathodic production of hydrogen peroxide and the simultaneous treatment of wastewater is investigated. Three types of three-dimensional electrodes - activated carbon particle electrodes (ACPE), carbon black particle electrodes (CBPE) and graphite particle electrodes (GPE) - are made of activated carbon (AC), carbon black (CB) and graphite powders respectively with polytetrafluoroethene (PTFE) as the binder. The MFC using the GPE is shown to perform best for catalyzing H2O2 production, while the MFCs equipped with the CBPE and the ACPE achieve a 17-18% higher power output but a 2.5-4.4% lower H2O2 yield, due to the further cathodic reduction of H2O2. Furthermore, a relatively high current in the system is demonstrated to have a positive impact on both cathodic H2O2 generation and anodic organic degradation for each MFC. At an external resistance of 20 Ω, the MFC using the GPE achieves the H2O2 generation of 196.50 mg L-1 and 84% COD removal in 24 h, with Coulombic efficiency, Faradic efficiency and COD conversion efficiency of 29%, 70%, and 20%, respectively. This study shows that MFC with carbon three-dimensional electrode is a cost-effective energy-saving bioelectrochemical system for the simultaneous production of hydrogen peroxide and removal of COD.

  11. Melatonin protects skin keratinocyte from hydrogen peroxide-mediated cell death via the SIRT1 pathway.

    Science.gov (United States)

    Lee, Ju-Hee; Moon, Ji-Hong; Nazim, Uddin Md; Lee, You-Jin; Seol, Jae-Won; Eo, Seong-Kug; Lee, John-Hwa; Park, Sang-Youel

    2016-03-15

    Melatonin (N-acetyl-5-methoxytryptamine), which is primarily synthesized in and secreted from the pineal gland, plays a pivotal role in cell proliferation as well as in the regulation of cell metastasis and cell survival in a diverse range of cells. The aim of this study is to investigate protection effect of melatonin on H2O2-induced cell damage and the mechanisms of melatonin in human keratinocytes. Hydrogen peroxide dose-dependently induced cell damages in human keratinocytes and co-treatment of melatonin protected the keratinocytes against H2O2-induced cell damage. Melatonin treatment activated the autophagy flux signals, which were identified by the decreased levels of p62 protein. Inhibition of autophagy flux via an autophagy inhibitor and ATG5 siRNA technique blocked the protective effects of melatonin against H2O2-induced cell death in human keratinocytes. And we found the inhibition of sirt1 using sirtinol and sirt1 siRNA reversed the protective effects of melatonin and induces the autophagy process in H2O2-treated cells. This is the first report demonstrating that autophagy flux activated by melatonin protects human keratinocytes through sirt1 pathway against hydrogen peroxide-induced damages. And this study also suggest that melatonin could potentially be utilized as a therapeutic agent in skin disease. PMID:26918354

  12. Melatonin protects skin keratinocyte from hydrogen peroxide-mediated cell death via the SIRT1 pathway

    Science.gov (United States)

    Lee, Ju-Hee; Moon, Ji-Hong; Nazim, Uddin MD.; Lee, You-Jin; Seol, Jae-Won; Eo, Seong-Kug; Lee, John-Hwa; Park, Sang-Youel

    2016-01-01

    Melatonin (N-acetyl-5-methoxytryptamine), which is primarily synthesized in and secreted from the pineal gland, plays a pivotal role in cell proliferation as well as in the regulation of cell metastasis and cell survival in a diverse range of cells. The aim of this study is to investigate protection effect of melatonin on H2O2-induced cell damage and the mechanisms of melatonin in human keratinocytes. Hydrogen peroxide dose-dependently induced cell damages in human keratinocytes and co-treatment of melatonin protected the keratinocytes against H2O2-induced cell damage. Melatonin treatment activated the autophagy flux signals, which were identified by the decreased levels of p62 protein. Inhibition of autophagy flux via an autophagy inhibitor and ATG5 siRNA technique blocked the protective effects of melatonin against H2O2-induced cell death in human keratinocytes. And we found the inhibition of sirt1 using sirtinol and sirt1 siRNA reversed the protective effects of melatonin and induces the autophagy process in H2O2-treated cells. This is the first report demonstrating that autophagy flux activated by melatonin protects human keratinocytes through sirt1 pathway against hydrogen peroxide-induced damages. And this study also suggest that melatonin could potentially be utilized as a therapeutic agent in skin disease. PMID:26918354

  13. Sporocidal properties of peracetic acid and hydrogen peroxide, alone and in combination, in comparison with chlorine and formaldehyde for ultrafiltration membrane disinfection.

    Science.gov (United States)

    Alasri, A; Valverde, M; Roques, C; Michel, G; Cabassud, C; Aptel, P

    1993-01-01

    The sporocidal properties of peracetic acid, hydrogen peroxide, chlorine, and formaldehyde were compared in vitro using a dilution-neutralization micromethod. A combination of peracetic acid and hydrogen peroxide was also tested to assess their interactions. The activities of these agents, which are widely used as disinfectants, were evaluated against Bacillus spore isolates found on stored membranes and collection cultures. Peracetic acid and chlorine exhibited an excellent antimicrobial activity, with a destruction of 10(5) spores/mL after 5 min of contact. Generally the effects of the biocides tested were time dependent. The sporocidal activities of hydrogen peroxide and formaldehyde were the lowest. The combination of peracetic acid and hydrogen peroxide, tested by a checkerboard micromethod, was found to be synergistic. The minimal sporocidal concentration (MSC) was established in terms of time for each biocide. The lowest MSC values for peracetic acid, hydrogen peroxide, chlorine, and formaldehyde were 168-336 ppm (1-2 h of contact), 5625-11250 ppm (5-7 h), 168-336 ppm (2-3 h), and 1875-3750 ppm (5-30 min), respectively. The MSC of a biocide combination of peracetic acid and hydrogen peroxide showed that synergy was maintained with increasing contact time and that the MSC could be reduced by two to eight times when compared with those of the biocides alone. Optimal concentrations and contact times of those chemicals that were promising in vitro were then tested for their ability to disinfect ultrafiltration membranes. The sporocidal activities of peroxide compounds and chlorine were confirmed and the synergism between peracetic acid and hydrogen peroxide was also maintained.(ABSTRACT TRUNCATED AT 250 WORDS) PMID:8439874

  14. Hydrogen peroxide generation induces pp60src activation in human platelets: evidence for the involvement of this pathway in store-mediated calcium entry.

    Science.gov (United States)

    Rosado, Juan A; Redondo, Pedro C; Salido, Ginés M; Gómez-Arteta, Emilio; Sage, Stewart O; Pariente, Jose A

    2004-01-16

    Reactive oxygen species, such as H2O2, have been recognized as intracellular messengers involved in several cell functions. Here we report the activation of the tyrosine kinase pp60(src) by H2O2, a mechanism required for the activation of store-mediated Ca2+ entry (SMCE) in human platelets. Treatment of platelets with H2O2 resulted in a time- and concentration-dependent activation of pp60(src). Incubation with GF 109203X, a protein kinase C (PKC) inhibitor, prevented H2O2-induced pp60(src) activation. In contrast, dimethyl-BAPTA loading did not affect this response, suggesting that activation of pp60(src) by H2O2 is independent of increases in [Ca2+](i). Cytochalasin D, an inhibitor of actin polymerization, significantly reduced H2O2-induced pp60(src) activation. We found that platelet stimulation with thapsigargin (TG) plus ionomycin (Iono) or thrombin induced rapid H2O2 production, a mechanism independent of elevations in [Ca2+](i). Treatment of platelets with catalase attenuated TG plus Iono- and thrombin-induced activation of pp60(src). In addition, catalase as well as the pp60(src) inhibitor, PP1, reduced both the activation of SMCE and the coupling between the hTrp1 and the IP(3)R type II without having any effect on the maintenance of SMCE. Consistent with the role of PKC in the activation of pp60(src) by H2O2, the PKC inhibitors GF 109202X and Ro-31-8220 were found to reduced SMCE in platelets. This study suggests that platelet activation with TG plus Iono or thrombin is associated with H2O2 production, which acts as a second messenger by stimulating pp60(src) by a PKC-dependent pathway and is involved in the activation of SMCE in these cells.

  15. Evaluation of bleaching efficacy of 37.5% hydrogen peroxide on human teeth using different modes of activations: An in vitro study

    Science.gov (United States)

    Bhutani, Neha; Venigalla, Bhuvan Shome; Patil, Jaya Prakash; Singh, Thakur Veerandar; Jyotsna, Sistla Venkata; Jain, Abhilasha

    2016-01-01

    Introduction: The aim of this in vitro study is to evaluate the role of light and laser sources in the bleaching ability of 37.5% H2 O2 on extracted human teeth. Materials and Methods: About 30 caries-free single-rooted maxillary central incisors were used for the study. Specimens were prepared by sectioning the crown portion of teeth mesiodistally, and labial surface was used for the study. Specimens were then immersed in coffee solution for staining. Color of each tooth was analyzed using Shadestar, a digital shademeter. Specimens were then divided into three groups of 10 each and were subjected to bleaching with 37.5% H2 O2, 37.5% H2 O2 + light activation, and 37.5% H2 O2 + laser activation, respectively. Postbleaching, the color was analyzed for all the specimens immediately and then after 1, 2, and 3 weeks intervals, respectively. Results: All the statistical analyses were done using SPSS version 17. Intra- and inter-group comparisons were done with Friedman test and Kruskal–Wallis ANOVA, respectively. Statistical analysis concluded with a significant improvement in their shade values from baseline in all the three groups. Halogen light activation and laser-activated groups showed comparatively enhanced bleaching results over no-activation group, though the difference was not statistically significant. Conclusion: The results of the present study show that bleaching assisted with halogen light and laser showed increased lightness than nonlight activated group. Durability of bleaching results obtained postbleaching was maintained throughout the experimental trail period of 3 weeks for both halogen light and laser activation group, whereas no-light activation group presented with shade rebound after 2 weeks postbleaching. PMID:27217641

  16. Taurine chloramine protects RAW 264.7 macrophages against hydrogen peroxide-induced apoptosis by increasing antioxidants

    OpenAIRE

    Piao, Shuyu; Cha, Young-Nam; Kim, Chaekyun

    2011-01-01

    Taurine chloramine is the major chloramine generated in activated neutrophils via the reaction between the overproduced hypochlorous acid and the stored taurine. Taurine chloramine has anti-inflammatory and cytoprotective effects in inflamed tissues by inhibiting the production of inflammatory mediators. Taurine chloramine increases heme oxygenase activity and also protects against hydrogen peroxide (H2O2)-derived necrosis in macrophages. In this study, we examined further whether taurine chl...

  17. Investigation of Influential Parameters in Deep Oxidative Desulfurization of Dibenzothiophene with Hydrogen Peroxide and Formic Acid

    Directory of Open Access Journals (Sweden)

    Alireza Haghighat Mamaghani

    2013-01-01

    Full Text Available An effective oxidative system consisting of hydrogen peroxide, formic acid, and sulfuric acid followed by an extractive stage were implemented to remove dibenzothiophene in the simulated fuel oil. The results revealed such a great performance in the case of H2O2 in the presence of formic and sulfuric acids that led to the removal of sulfur compounds. Sulfuric acid was employed to increase the acidity of media as well as catalytic activity together with formic acid. The oxidation reaction was followed by a liquid-liquid extraction stage using acetonitrile as a polar solvent to remove produced sulfones from the model fuel. The impact of operating parameters including the molar ratio of formic acid to sulfur (, hydrogen peroxide to sulfur (, and the time of reaction was investigated using Box-Behnken experimental design for oxidation of the model fuel. A significant quadratic model was introduced for the sulfur removal as a function of effective parameters by the statistic analysis.

  18. Molecular and Cellular Effects of Hydrogen Peroxide on Human Lung Cancer Cells: Potential Therapeutic Implications

    Science.gov (United States)

    2016-01-01

    Lung cancer has a very high mortality-to-incidence ratio, representing one of the main causes of cancer mortality worldwide. Therefore, new treatment strategies are urgently needed. Several diseases including lung cancer have been associated with the action of reactive oxygen species (ROS) from which hydrogen peroxide (H2O2) is one of the most studied. Despite the fact that H2O2 may have opposite effects on cell proliferation depending on the concentration and cell type, it triggers several antiproliferative responses. H2O2 produces both nuclear and mitochondrial DNA lesions, increases the expression of cell adhesion molecules, and increases p53 activity and other transcription factors orchestrating cancer cell death. In addition, H2O2 facilitates the endocytosis of oligonucleotides, affects membrane proteins, induces calcium release, and decreases cancer cell migration and invasion. Furthermore, the MAPK pathway and the expression of genes related to inflammation including interleukins, TNF-α, and NF-κB are also affected by H2O2. Herein, we will summarize the main effects of hydrogen peroxide on human lung cancer leading to suggesting it as a potential therapeutic tool to fight this disease. Because of the multimechanistic nature of this molecule, novel therapeutic approaches for lung cancer based on the use of H2O2 may help to decrease the mortality from this malignancy. PMID:27375834

  19. Solar energy conversion by green microalgae: a photosystem for hydrogen peroxide production.

    Science.gov (United States)

    de la Rosa, F F; Montes, O; Galván, F

    2001-09-20

    A photosystem for solar energy conversion, comprised of a culture of green microalgae supplemented with methyl viologen, is proposed. The capture of solar energy is based on the Mehler reaction. The reduction of methyl viologen by the photosynthetic apparatus and its subsequent reoxidation by oxygen produces hydrogen peroxide. This is a rich-energy compound that can be used as a nonpollutant and efficient fuel. Four different species of green microalgae, Chlamydomonas reinhardtii (21gr) C. reinhardtii (CW15), Chlorella fusca, and Monoraphidium braunii, were tested as a possible biocatalyst. Each species presented a different efficiency level in the transformation of energy. Azide was an efficient inhibitor of the hydrogen peroxide scavenging system while maintaining photosynthetic activity of the microalgae, and thus significantly increasing the production of the photosystem. The strain C. reinhardtii (21gr), among the species studied, was the most efficient with an initial production rate of 185 micromol H(2)O(2)/h x mg Chl and reaching a maximum of 42.5 micromol H(2)O(2)/mg Chl when assayed in the presence of azide inhibitor. PMID:11494222

  20. DISY. The direct synthesis of hydrogen peroxide, a bridge for innovative applications

    Energy Technology Data Exchange (ETDEWEB)

    Buzzoni, R.; Perego, C. [Eni S.p.A., Novara (Italy). Research Center for Non-Conventional Energies

    2011-07-01

    Hydrogen peroxide is largely recognized as the green oxidant of choice for future sustainable processes. The current industrial production still goes through the old anthraquinone process, a complex, two-step process suffering from a low specific productivity. Following the development of TS-1/H{sub 2}O{sub 2} based selective oxidation processes e.g. propylene epoxidation, cyclohexanone ammoximation and the new benzene direct oxidation to phenol, there has been an incentive for the development of a new technology, simpler and with better economics. DISY process, based on direct synthesis of hydrogen peroxide from hydrogen and oxygen, is highly suitable to the design of integrated selective oxidation processes as well as for production of commercial-grade high concentration aqueous hydrogen peroxide solutions. Catalyst and process development up to pilot scale are described. (orig.)

  1. ITO electrode modified by a gold ion implantation technique for direct electrocatalytic sensing of hydrogen peroxide

    International Nuclear Information System (INIS)

    We report on a simple strategy for the fabrication of gold nanoparticles (AuNPs) on an indium tin oxide substrate using a modified ion implantation method. The morphology, structure and electrochemical features of AuNPs were characterized by atomic force microscopy, electrochemical impedance spectroscopy and cyclic voltammetry. The modified electrode has a large electrochemically active surface and enables strong loading with cytochrome c (Cyt c) proteins. It undergoes enhanced electron transfer at uncompromised electrochemical activity, and also displays good stability and repeatability. The immobilized Cyt c exhibits good electrocatalytic activity towards hydrogen peroxide (H2O2), with a linear relationship between the catalytic current during differential pulse voltammetry and the concentration of H2O2 in the 0.05 μM to 0.2 μM range. The detection limit (S/N = 3) is 0. 01 μM. (author)

  2. Azide protection of bacteroides superoxide dismutases from inactivation by hydrogen peroxide

    International Nuclear Information System (INIS)

    The anaerobes Bacteroides fragilis, B. distasonis and B. thetaiotaomicron produce an iron-containing superoxide dismutase (FeSOD). These FeSODs are reversibly inhibited by 1 mM azide (NaN3) and are irreversibly inactivated upon incubation with hydrogen peroxide (H2O2). H2O2 inactivation of the enzyme likely depends on a Fenton type reaction with the production of hydroxyl radical (OH). Addition of NaN3 to the enzyme solution decreased the rate of inactivation by H2O2. After 20 minutes incubation of purified B. distasonis FeSOD with 2.5 mM H2O2, 61% of the initial enzymatic activity remained when 1 mM NaN3 was also present compared with 29% activity without NaN3. Similar results were seen with FeSOD from B. fragilis and B. thetaiotaomicron. Metal analyses of the native, peroxidized, and NaN3 protected samples are consistent with loss of Fe from the enzyme upon peroxidation, but retention of Fe and enzymatic activity in the NaN3 protected sample. Protection of FeSOD activity from H2O2 inactivation was dependent on NaN3 concentration. Anionic hydroxyl radical scavengers, such as urate and xanthine did not significantly protect the enzyme. The results are consistent with binding of azide to the active site either preventing entry of H2O2 or altering Fe redox potential, preventing OH production

  3. Cytoplasmic expression of recombinant interleukin-2 and interleukin-4 proteins results in hydrogen peroxide accumulation and reduction in catalase activity in Escherichia coli

    Directory of Open Access Journals (Sweden)

    M.S Hejazi

    2009-08-01

    Full Text Available Background and the purpose of the study: The Reactive oxygen species (ROS is induced in the cells following various stresses but the effect of recombinant protein expression on ROS generation has not been studied yet. In this study, H2O2 concentration and catalase activity variations and their correlation with cell growth following cytoplasmic expression of human interleukin-2 (hIL-2 and mouse interleukin-4 (mIL-4 in Escherichia coli were investigated. Additionally, the effect of recombinant protein expression under different conditions was compared to the effect of foreign DNA introduction on these factors. Methods: Plasmids pEThIL-2 and pETmIL-4 were used for expression of human interleukin-2 (hIL-2 and mouse interleukin-4 (mIL-4 inside the cytoplasm of the cells. Having confirmed protein expression using SDS-PAGE analysis and ELISA assay, H2O2 concentration and catalase activity were measured at various ODs. Results and major conclusion: Empty vector introduction increased significantly H2O2 concentration of the cells. However, H2O2 concentration in hIL-2 and mIL-4 expressing cells was significantly higher than its concentration in empty vector transformed cells. Catalase activity was reduced in foreign DNA introduced cells. It was more lowered following expression of recombinant proteins. Results of this study revealed the relationship between foreign DNA introduction and protein expression with H2O2 elevation and catalase activity reduction. There was also correlation between H2O2 elevation and reduction in catalase activity with the cell growth depression.

  4. Characterization of hydrogen peroxide-resistant Acinetobacter species isolated during the Mars Phoenix spacecraft assembly.

    Science.gov (United States)

    Derecho, I; McCoy, K B; Vaishampayan, P; Venkateswaran, K; Mogul, R

    2014-10-01

    The microbiological inventory of spacecraft and the associated assembly facility surfaces represent the primary pool of forward contaminants that may impact the integrity of life-detection missions. Herein, we report on the characterization of several strains of hydrogen peroxide-resistant Acinetobacter, which were isolated during the Mars Phoenix lander assembly. All Phoenix-associated Acinetobacter strains possessed very high catalase specific activities, and the specific strain, A. gyllenbergii 2P01AA, displayed a survival against hydrogen peroxide (no loss in 100 mM H2O2 for 1 h) that is perhaps the highest known among Gram-negative and non-spore-forming bacteria. Proteomic characterizations reveal a survival mechanism inclusive of proteins coupled to peroxide degradation (catalase and alkyl hydroperoxide reductase), energy/redox management (dihydrolipoamide dehydrogenase), protein synthesis/folding (EF-G, EF-Ts, peptidyl-tRNA hydrolase, DnaK), membrane functions (OmpA-like protein and ABC transporter-related protein), and nucleotide metabolism (HIT family hydrolase). Together, these survivability and biochemical parameters support the hypothesis that oxidative tolerance and the related biochemical features are the measurable phenotypes or outcomes for microbial survival in the spacecraft assembly facilities, where the low-humidity (desiccation) and clean (low-nutrient) conditions may serve as selective pressures. Hence, the spacecraft-associated Acinetobacter, due to the conferred oxidative tolerances, may ultimately hinder efforts to reduce spacecraft bioburden when using chemical sterilants, thus suggesting that non-spore-forming bacteria may need to be included in the bioburden accounting for future life-detection missions. PMID:25243569

  5. Characterization of hydrogen peroxide-resistant Acinetobacter species isolated during the Mars Phoenix spacecraft assembly.

    Science.gov (United States)

    Derecho, I; McCoy, K B; Vaishampayan, P; Venkateswaran, K; Mogul, R

    2014-10-01

    The microbiological inventory of spacecraft and the associated assembly facility surfaces represent the primary pool of forward contaminants that may impact the integrity of life-detection missions. Herein, we report on the characterization of several strains of hydrogen peroxide-resistant Acinetobacter, which were isolated during the Mars Phoenix lander assembly. All Phoenix-associated Acinetobacter strains possessed very high catalase specific activities, and the specific strain, A. gyllenbergii 2P01AA, displayed a survival against hydrogen peroxide (no loss in 100 mM H2O2 for 1 h) that is perhaps the highest known among Gram-negative and non-spore-forming bacteria. Proteomic characterizations reveal a survival mechanism inclusive of proteins coupled to peroxide degradation (catalase and alkyl hydroperoxide reductase), energy/redox management (dihydrolipoamide dehydrogenase), protein synthesis/folding (EF-G, EF-Ts, peptidyl-tRNA hydrolase, DnaK), membrane functions (OmpA-like protein and ABC transporter-related protein), and nucleotide metabolism (HIT family hydrolase). Together, these survivability and biochemical parameters support the hypothesis that oxidative tolerance and the related biochemical features are the measurable phenotypes or outcomes for microbial survival in the spacecraft assembly facilities, where the low-humidity (desiccation) and clean (low-nutrient) conditions may serve as selective pressures. Hence, the spacecraft-associated Acinetobacter, due to the conferred oxidative tolerances, may ultimately hinder efforts to reduce spacecraft bioburden when using chemical sterilants, thus suggesting that non-spore-forming bacteria may need to be included in the bioburden accounting for future life-detection missions.

  6. MODIFIED OPAL: A NOVEL STABILIZER FOR HYDROGEN PEROXIDE BLEACHING OF PULPS

    Institute of Scientific and Technical Information of China (English)

    XuerenQian; XianhuiAn; WenboLiu; GangYu; ZhanqianSong

    2004-01-01

    The possibility of modified opal as the stabilizer ofhydrogen peroxide bleaching was investigated. Theresults showed that the modified opal in place ofsodium silicate as the stabilizer of hydrogen peroxidebleaching is feasible. At the same dosage, above 3%ISO can be increased for both wheat straw pulp anddeinked pulp. The stabilizing ability of the modifiedopal to hydrogen peroxide bleaching of pulp isimproved markedly. It is favorable for bleaching toincrease temperature and time within a permissiveextent. The suitable process conditions are I0% ofpulp consistency, 3% of hydrogen peroxide, 1.5% ofsodium hydroxide, 3% of the modified opal, 70~"and 60 min when the modified opal is used as thestabilizer of hydrogen peroxide bleaching. At theseconditions, the brightness gain can reach about 16%ISO for wheat straw pulp. In addition, it is favorablefor bleaching to add a little magnesium sulfate whenthe modified opal is used as the stabilizer ofhydrogen peroxide bleaching, the brightness of pulpcan increase 1%ISO if0.05% of magnesium sulfate isadded. The cost analysis indicated that the modifiedopal is superior to sodium silicate as the stabilizer ofhydrogen peroxide bleaching in economical aspectand has further the potential of market development.

  7. Cytoplasmic expression of recombinant interleukin-2 and interleukin-4 proteins results in hydrogen peroxide accumulation and reduction in catalase activity in Escherichia coli

    OpenAIRE

    M.S Hejazi; F Karimi; E Mehdizadeh Aghdam; Barzegari, A. (MSc); M Farshdosti Hagh; Parvizi, M.; L Mahmoodi Azar; Hejazi, M. A.

    2009-01-01

    Background and the purpose of the study: The Reactive oxygen species (ROS) is induced in the cells following various stresses but the effect of recombinant protein expression on ROS generation has not been studied yet. In this study, H2O2 concentration and catalase activity variations and their correlation with cell growth following cytoplasmic expression of human interleukin-2 (hIL-2) and mouse interleukin-4 (mIL-4) in Escherichia coli were investigated. Additionally, the effect of recombina...

  8. Improved activity and thermo-stability of the horse radish peroxidase with graphene quantum dots and its application in fluorometric detection of hydrogen peroxide

    Science.gov (United States)

    Xiaoyan, Zhou; Yuanyuan, Jiang; Zaijun, Li; Zhiguo, Gu; Guangli, Wang

    2016-08-01

    Graphene quantum dots (GQDs) have received extensive concern in many fields such as optical probe, bioimaging and biosensor. However, few reports refer on the influence of GQDs on enzyme performance. The paper reports two kinds of graphene quantum dots (termed as GO-GQDs and N,S-GQDs) that were prepared by cutting of graphene oxide and pyrolysis of citric acid and L-cysteine, and their use for the horse radish peroxidase (HRP) modification. The study reveals that GO-GQDs and N,S-GQDs exhibit an opposite effect on the HRP performance. Only HRP modified with GO-GQDs offers an enhanced activity (more than 1.9 times of pristine enzyme) and thermo-stability. This is because GO-GQDs offer a larger conjugate rigid plane and fewer hydrophilic groups compared to N,S-GQDs. The characteristics can make GO-GQDs induce a proper conformational change in the HRP for the catalytic performance, improving the enzyme activity and thermo-stability. The HRP modified with green luminescent GO-GQDs was also employed as a biocatalyst for sensing of H2O2 by a fluorometric sensor. The colorless tetramethylbenzidine (TMB) is oxidized into blue oxidized TMB in the presence of H2O2 by the assistance of HRP/GO-GQDs, leading to an obvious fluorescence quenching. The fluorescence intensity linearly decreases with the increase of H2O2 concentration in the range from 2 × 10 - 9 to 2 × 10 - 4 M with the detection limit of 6.8 × 10 - 10 M. The analytical method provides the advantage of sensitivity, stability and accuracy compared with present H2O2 sensors based on the pristine HRP. It has been successfully applied in the determination of H2O2 in real water samples. The study also opens a new avenue for modification of enzyme activity and stability that offers great promise in applications such as biological catalysis, biosensing and enzyme engineering.

  9. Hydrogen Peroxide and Polyamines Act as Double Edged Swords in Plant Abiotic Stress Responses.

    Science.gov (United States)

    Gupta, Kamala; Sengupta, Atreyee; Chakraborty, Mayukh; Gupta, Bhaskar

    2016-01-01

    The specific genetic changes through which plants adapt to the multitude of environmental stresses are possible because of the molecular regulations in the system. These intricate regulatory mechanisms once unveiled will surely raise interesting questions. Polyamines and hydrogen peroxide have been suggested to be important signaling molecules during biotic and abiotic stresses. Hydrogen peroxide plays a versatile role from orchestrating physiological processes to stress response. It helps to achieve acclimatization and tolerance to stress by coordinating intra-cellular and systemic signaling systems. Polyamines, on the other hand, are low molecular weight polycationic aliphatic amines, which have been implicated in various stress responses. It is quite interesting to note that both hydrogen peroxide and polyamines have a fine line of inter-relation between them since the catabolic pathways of the latter releases hydrogen peroxide. In this review we have tried to illustrate the roles and their multifaceted functions of these two important signaling molecules based on current literature. This review also highlights the fact that over accumulation of hydrogen peroxide and polyamines can be detrimental for plant cells leading to toxicity and pre-mature cell death. PMID:27672389

  10. Role of mitochondrial dysfunction in hydrogen peroxide-induced apoptosis of intestinal epithelial cells

    Institute of Scientific and Technical Information of China (English)

    Jian-Ming Li; Hong Zhou; Qian Cai; Guang-Xia Xiao

    2003-01-01

    AIM: To study the role of mitochondrial dysfunction in hydrogen peroxide-induced apoptosis of intestinal epithelial cells.METHODS: Hydrogen peroxide-induced apoptosis of human intestinal epithelial cell line SW-480 was established. Cell apoptosis was determined by Annexin-V and PI doublestained flow cytometry and DNA gel electrophoresis.Morphological changes were examined with light and electron microscopy. For other observations, mitochondrial function,cytochrome c release, mitochondrial translocation and membrane potential were determined simultaneously.RESULTS: Percentage of apoptotic cells induced with 400μ mol/L hydrogen peroxide increased significantly at I h or 3h after stimulation and recovered rapidly. Meanwhile percentage of apoptotic cells induced with 4 mmol/L hydrogen peroxide increased with time. In accordance with these changes, we observed decreased mitochondrial function in 400 μmol/L H2O2-stimualted cells at 1 h or 3 h and in 4 mmol/L H2O2-stimualted cells at times examined.Correspondingly, swelling cristae and vacuole-like mitochondria were noted. Release of cytochrome c,decreased mitochondrial membrane potential and mitochondrial translocation were also found to be the early signs of apoptosis.CONCLUSION: Dysfunctional mitochondria play a role in the apoptosis of SW-480 cell line induced by hydrogen peroxide.

  11. Hydrogen peroxide inhibits transforming growth factor-β1-induced cell cycle arrest by promoting Smad3 linker phosphorylation through activation of Akt-ERK1/2-linked signaling pathway

    Energy Technology Data Exchange (ETDEWEB)

    Choi, Jiyeon; Park, Seong Ji; Jo, Eun Ji [Department of Biochemistry, College of Natural Sciences, Kangwon National University, Chuncheon 200-701 (Korea, Republic of); Lee, Hui-Young [Department of Internal Medicine, Kangwon National University, Chuncheon 200-701 (Korea, Republic of); Hong, Suntaek [Laboratory of Cancer Cell Biology, Lee Gil Ya Cancer and Diabetes Institute, Gachon University, Incheon 406-840 (Korea, Republic of); Kim, Seong-Jin [CHA Cancer Institute, CHA University of Medicine and Science, Seoul 135-081 (Korea, Republic of); Kim, Byung-Chul, E-mail: bckim@kangwon.ac.kr [Department of Biochemistry, College of Natural Sciences, Kangwon National University, Chuncheon 200-701 (Korea, Republic of)

    2013-06-14

    Highlights: •H{sub 2}O{sub 2} inhibits TGF-β1-induced cell cycle arrest. •H{sub 2}O{sub 2} induces Smad3 linker phosphorylation through Akt-ERK1/2 pathway. •H{sub 2}O{sub 2}-mediated suppression of TGF-β signal requires Smad3 linker phosphorylation. •This is a first report about interplay between H{sub 2}O{sub 2} and growth inhibition pathway. -- Abstract: Hydrogen peroxide (H{sub 2}O{sub 2}) functions as a second messenger in growth factor receptor-mediated intracellular signaling cascade and is tumorigenic by virtue of its ability to promote cell proliferation; however, the mechanisms underlying the growth stimulatory action of H{sub 2}O{sub 2} are less understood. Here we report an important mechanism for antagonistic effects of H{sub 2}O{sub 2} on growth inhibitory response to transforming growth factor-β1 (TGF-β1). In Mv1Lu and HepG2 cells, pretreatment of H{sub 2}O{sub 2} (0.05–0.2 mM) completely blocked TGF-β1-mediated induction of p15{sup INK4B} expression and increase of its promoter activity. Interestingly, H{sub 2}O{sub 2} selectively suppressed the transcriptional activation potential of Smad3, not Smad2, in the absence of effects on TGF-β1-induced phosphorylation of the COOH-tail SSXS motif of Smad3 and its nuclear translocation. Mechanism studies showed that H{sub 2}O{sub 2} increases the phosphorylation of Smad3 at the middle linker region in a concentration- and time-dependent manner and this effect is mediated by activation of extracellular signal-activated kinase 1/2 through Akt. Furthermore, expression of a mutant Smad3 in which linker phosphorylation sites were ablated significantly abrogated the inhibitory effects of H{sub 2}O{sub 2} on TGF-β1-induced increase of p15{sup INK4B}-Luc reporter activity and blockade of cell cycle progression from G1 to S phase. These findings for the first time define H{sub 2}O{sub 2} as a signaling molecule that modulate Smad3 linker phosphorylation and its transcriptional activity, thus providing

  12. Foodomics study on the effects of extracellular production of hydrogen peroxide by rosemary polyphenols on the anti-proliferative activity of rosemary polyphenols against HT-29 cells.

    Science.gov (United States)

    Valdés, Alberto; García-Cañas, Virginia; Koçak, Engin; Simó, Carolina; Cifuentes, Alejandro

    2016-07-01

    A number of studies have demonstrated a strong association between the antioxidant properties of rosemary polyphenols and their chemoprotective activity. However, the prooxidant effects of rosemary polyphenols have been rarely reported. In this work, a foodomics study is performed to investigate the in vitro autooxidation of carnosic acid (CA), carnosol (CS) and a polyphenol-enriched rosemary extract (SC-RE) in cell culture conditions. The results revealed that rosemary polyphenols autooxidation in culture medium generated H2 O2 at different rates. Generated H2 O2 levels by SC-RE and CA, but not CS, were correlated with intracellular reactive oxygen species (ROS) generation in HT-29 cells, and were partially involved in their anti-proliferative effect in this cell line. These compounds also induced different effects on glutathione metabolism. Results also indicated that high extracellular H2 O2 concentrations, resulting of using high (45 μg/mL) SC-RE concentration in culture media, exerted some artifactual effects related with cell cycle, but they did not influence the expression of relevant molecular biomarkers of stress. PMID:26842614

  13. Roles of Catalase and Trehalose in the Protection from Hydrogen Peroxide Toxicity in Saccharomyces cerevisiae.

    Science.gov (United States)

    Nishimoto, Takuto; Watanabe, Takeru; Furuta, Masakazu; Kataoka, Michihiko; Kishida, Masao

    2016-01-01

    The roles of catalase and trehalose in Saccharomyces cerevisiae subject to hydrogen peroxide (H2O2) treatment were examined by measuring the catalase activity and intracellular trehalose levels in mutants lacking catalase or trehalose synthetase. Intracellular trehalose was elevated but the survival rate after H2O2 treatment remained low in mutants with deletion of the Catalase T gene. On the other hand, deletion of the trehalose synthetase gene increased the catalase activity in mutated yeast to levels higher than those in the wild-type strain, and these mutants exhibited some degree of tolerance to H2O2 treatment. These results suggest that Catalase T is critical in the yeast response to oxidative damage caused by H2O2 treatment, but trehalose also plays a role in protection against H2O2 treatment. PMID:27667523

  14. Electrochemical detection of hydrogen peroxide at a waxed graphite electrode modified with platinum-decorated carbon nanotubes

    Institute of Scientific and Technical Information of China (English)

    SHI Qiao-cui; ZENG Wen-fang; ZHU Yunu

    2009-01-01

    Platinum-decorated carbon nanotubes (CNT-Pt) were produced by the chemical reduction method. A novel modified electrode was fabricated by intercalated CNT-Pt in the surface of waxed graphite, which provided excellent electro-catalytic activity and selectivity for both oxidation and reduction of hydrogen peroxide. The current response of the modified electrode for hydrogen peroxide was very rapid and the detection limits in amperometry are 2.5×10-6 mol/L at reduction potential and 4.8×10-6 mol/L at oxidation potential. It was desmonstrated that the electrode with high electro-activity was a suitable basic electrode for preparing enzyme electrode.

  15. Influence of sericin in alleviating the hydrogen peroxide induced oxidative stress in silkworm Bombyx mori: role of the amino acids

    OpenAIRE

    AS Micheal; Subramanyam, M

    2014-01-01

    Sericin is an important peptide derived from silk fibre spun by the silkworm Bombyx mori and has various biological activities. The aim of the present study was to characterize the major constituents of sericin that are providing cytoprotective effect against hydrogen peroxide-induced cell damage in midgut epithelial cells and hemocytes of silkworm. Extracted sericin was subjected to LCMS analysis for amino acid composition. Isolated cells of midgut and hemocytes were incubated with sericin o...

  16. Environmentally acceptable effect of hydrogen peroxide on cave 'lamp-flora', calcite speleothems and limestones

    International Nuclear Information System (INIS)

    Hydrogen peroxide plus limestone fragments allows removal of organisms without corrosion of limestone and speleothem. - Mosses, algae, and cyanobacteria (lamp-flora) colonize illuminated areas in show caves. This biota is commonly removed by a sodium hypochlorite solution. Because chlorine and other deleterious compounds are released into a cave environment during lamp-flora cleansing, hydrogen peroxide was tested as an alternative agent. In a multidisciplinary study conducted in the Katerinska Cave (Moravian Karst, Czech Republic), 12 algae- and cyanobacteria taxons and 19 moss taxons were detected. The threshold hydrogen peroxide concentration for the destruction of this lamp-flora was found to be 15 vol.%. Based on laboratory experiments in stirred batch reactors, the dissolution rates of limestones and calcite speleothems in water were determined as 3.77x10-3 and 1.81x10-3 mol m-2 h-1, respectively. In the 15% peroxide solution, the limestone and speleothem dissolution rates were one order of magnitude higher, 2.00x10-2 and 2.21x10-2 mol m-2 h-1, respectively. So, the peroxide solution was recognised to attack carbonates somewhat more aggressively than karst water. In order to prevent the potential corrosion of limestone and speleothems, the reaching of preliminary peroxide saturation with respect to calcite is recommended, for example, by adding of few limestone fragments into the solution at least 10 h prior to its application

  17. Investigation of the oxidation of hydrochloric acid in scrubbing solutions containing hydrogen peroxide

    International Nuclear Information System (INIS)

    Oxidation and absorption of nitrogen oxides by a solution containing sulphuric, nitric acids and hydrogen peroxide have been investigated. The oxidation of nitric oxide is dependent among others on hydrogen peroxide concentration total acidity and temperature. The absorption of N O2 by the scrubbing solution (H2 S O4,H N O3 and H2 O2) in all cases studied is not less than 98%. The oxidation of chloride into chlorine gas increases as the concentration of each of hydrochloric acid, nitric oxide and nitric acid increases. On the other hand as the concentration of hydrogen peroxide increases the amount of chlorine gas decreases. The results show that the oxidation of chloride into chlorine gas is mainly due to nitrogen dioxide. 7 fig., 2 tab

  18. Chemiluminescence assay for catechin based on generation of hydrogen peroxide in basic solution

    International Nuclear Information System (INIS)

    We have determined that the catechin group in basic solution efficiently produces hydrogen peroxide; moreover, a highly sensitive analysis methodology was developed to measure catechin employing a peroxalate chemiluminescence detection system. Identification of hydrogen peroxide generated by catechin was determined by ESR as well as peroxalate chemiluminescence using catalase and SOD. As a result, catechin-generated superoxide by electron reduction to dissolved oxygen in basic solution, followed by production of hydrogen peroxide through dismutation reaction. This method could measure several tea catechins, (+)-catechin (CC), (-)-epigallocatechin-3-gallate (EGCg), (-)-epicatechin-3-gallate (ECG) and gallic acid, with measurement range from 10-7 to 10-3 mol/l and sensitivity of 10-8 mol/l. This method was also applied to the determination of total catechin levels in green tea, black tea and roasted green tea

  19. Influence of sericin in alleviating the hydrogen peroxide induced oxidative stress in silkworm Bombyx mori: role of the amino acids

    Directory of Open Access Journals (Sweden)

    AS Micheal

    2014-09-01

    Full Text Available Sericin is an important peptide derived from silk fibre spun by the silkworm Bombyx mori and has various biological activities. The aim of the present study was to characterize the major constituents of sericin that are providing cytoprotective effect against hydrogen peroxide-induced cell damage in midgut epithelial cells and hemocytes of silkworm. Extracted sericin was subjected to LCMS analysis for amino acid composition. Isolated cells of midgut and hemocytes were incubated with sericin or with mixture of serine and aspartic acid prior to suboptimal concentration of hydrogen peroxide treatment. Sericin as well as amino acid mixture reduced the activity of antioxidant enzymes triggered by hydrogen peroxide, inhibited oxidative derivatives such as protein carbonyl and malondialdehyde and increased antioxidant capacity in both the cells studied. Furthermore, sericin and amino acid mixture significantly decreased intracellular reactive oxygen species as assessed by fluorescent detection. These results suggest that major constituent amino acids of sericin defend midgut epithelial cells and hemocytes against oxidative damage by scavenging reactive oxygen species rather than activating antioxidant enzyme system thereby inhibiting cell damage.

  20. Influence of hydrogen peroxide bleaching gels on color, opacity, and fluorescence of composite resins.

    Science.gov (United States)

    Torres, C R G; Ribeiro, C F; Bresciani, E; Borges, A B

    2012-01-01

    The aim of the present study was to evaluate the effect of 20% and 35% hydrogen peroxide bleaching gels on the color, opacity, and fluorescence of composite resins. Seven composite resin brands were tested and 30 specimens, 3-mm in diameter and 2-mm thick, of each material were fabricated, for a total of 210 specimens. The specimens of each tested material were divided into three subgroups (n=10) according to the bleaching therapy tested: 20% hydrogen peroxide gel, 35% hydroxide peroxide gel, and the control group. The baseline color, opacity, and fluorescence were assessed by spectrophotometry. Four 30-minute bleaching gel applications, two hours in total, were performed. The control group did not receive bleaching treatment and was stored in deionized water. Final assessments were performed, and data were analyzed by two-way analysis of variance and Tukey tests (pColor changes were significant for different tested bleaching therapies (pcolor change observed for 35% hydrogen peroxide gel. No difference in opacity was detected for all analyzed parameters. Fluorescence changes were influenced by composite resin brand (pbrand Z350. It was concluded that 35% hydrogen peroxide bleaching gel generated the greatest color change among all evaluated materials. No statistical opacity changes were detected for all tested variables, and significant fluorescence changes were dependent on the material and bleaching therapy, regardless of the gel concentration. PMID:22433032

  1. Chemiluminescence behavior of sodium hydrogen carbonate in the potassium permanganate-hydrogen peroxide reaction

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    Chemiluminescence (CL) phenomenon of hydrogen peroxide with potassium permanganate in the presence of sodium hydrogen carbonate was reported.Effects of the surfactant on the CL system were investigated.Nonionic surfactants could effectively increase the CL signal.Radical scavengers and organic reagents such as nitro blue tetrazolium chloride (NBT),cytochrome c,sodium azide,ascorbic acid,thiourea,tert-butanol and dimethyl sulphoxide were used to study the emitting species.CL emission spectrum was recorded and the results showed that the maximal emission wavelengths of NaHCO3-H2O2-KMnO4 system were 440 and 634 nm.The mechanism was discussed based on electron spin resonance (ESR) spectra,fluorescence spectra and UV-vis absorption spectra.The addition of rhodamine B or uranine into this CL system enhanced the CL signal.It was due to part of the energy transfer from singlet oxygen and excited triplet dimers of two CO2 molecules to rhodamine B or uranine.The CL could be induced by excited rhodamine B or uranine.

  2. Efficient hydrogen peroxide decomposition to oxygen and water catalysed by a ruthenium pincer complex

    DEFF Research Database (Denmark)

    Nielsen, Martin

    2016-01-01

    Hydrogen peroxide decomposition is a major issue in medicine, energy, and environmental sciences. For example, findings could lead to the development of efficient H2O2 removal systems to clean wastewaters. Here I tested several homogeneous catalysts for H2O2 decomposition. I found that a dihydride...... are necessary, further enhancing the potential scope of this system. By the use of the homogeneous catalyst Ru(H)2(PNPiPr)CO, it is possible to obtain turnover frequencies reaching 180,000 h−1 and turnover numbers more than 14,000 in a neutral hydrogen peroxide aqueous solution at 25 °C. Overall, findings...

  3. The Erosion Properties of Chlorine Dioxide and Hydrogen Peroxide on Bovine Teeth

    OpenAIRE

    Ablal MA; Jarad FD; Adeyemi AA

    2015-01-01

    Objectives: The aim of this study was to assess the erosion potential of chlorine dioxide and hydrogen peroxide on bovine teeth. Methods: Sixty bovine crowns were ground and polished to give flat surfaces. The crowns were subjected to heavy staining cycles then equally divided into 3 treatment groups; chlorine dioxide (ClO2), hydrogen peroxide (H2O2), and deionised water (H2O). Specimens in each group were immersed in 150 ml of the treatment for seven 2 min cycle in addition...

  4. A new process for preparing dialdehyde by catalytic oxidation of cyclic olefins with aqueous hydrogen peroxide

    Institute of Scientific and Technical Information of China (English)

    YU, Hong-Kun; PANG, Zhen; HUANG, Zu-En; CAI, Rui-Fang

    2000-01-01

    A novel peroxo-nioboplosphate was synthesized for the first time and used as a catalyst in the oxidation reaction of cyclic olefins with aqueous hydrogen peroxide to prepare dialdehydes. The catalyst was characterized by elemental analysis,thermographic analyses, IR, UV/vis, 31P NMR and XPS ~ as [ π-C5H5N(CH2)i3CH3 ]2 [Nb406 (O2)2 (PO4)2] ·6H20 (PTNP). It showed high selectivity to glutaraldehyde in the catalytic oxidation of cyclopentene with aqueous hydrogen peroxide in ethanol.

  5. Kinetic study of hexavalent plutonium reduction by hydrogen peroxide in acid solution

    International Nuclear Information System (INIS)

    The kinetics of the reduction of hexavalent plutonium by hydrogen peroxide has been studied in perchloric, sulphuric and nitric acids. The rate of reduction is proportional to the initial concentrations of plutonium and of hydrogen peroxide and is inversely proportional to the acidity. The values of the proportionality constant k have been determined. They are very dependent on the temperature, on the ionic force and on the nature of the anion of the acid medium. An interpretation is put forward, based on the experimental results, attributing an important role to the hydrolysed species PuO2(OH)+ in the reduction kinetics. (author)

  6. Cell-death-mode switch from necrosis to apoptosis in hydrogen peroxide treated macrophages

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    Cell death is typically defined either as apoptosis or necrosis. Because the consequences of apoptosis and necrosis are quite different for an entire organism, the investigation of the cell-death-mode switch has considerable clinical significance. The existence of a necrosis-to-apoptosis switch induced by hydrogen peroxide in macrophage cell line RAW 264.7 cells was confirmed by using flow cytometry and fluorescence microscopy. With the help of computational simulations, this study predicted that negative feedbacks between NF-κB and MAPKs are implicated in converting necrosis into apoptosis in macrophages exposed to hydrogen peroxide, which has significant implications.

  7. Neutral water-chemical regime with hydrogen peroxide dosage at the AMB-200 unit

    International Nuclear Information System (INIS)

    Results of investigations related to estimation of erosion-corrosion process rates on feed water treatment with hydrogen peroxide at the Beloyarskaya NPP second unit are given. As follows from analysis, values of electric conductivity and iron oxide concentrations reduced two times as compared with correctionless regimes. Metal erosion rate in some feed water loop sections reduced 200-600 times. Hydrogen peroxide metering for feed water provides good condition and reliable operation of feed water loop equipment, reactor circuit and process tubes of the AMB-200 reactor unit

  8. Process Development and Design of Chlorine Dioxide Production Based on Hydrogen Peroxide

    Institute of Scientific and Technical Information of China (English)

    陈赟; 江燕斌; 钱宇

    2004-01-01

    This paper presents a process development and design of chlorine dioxide production based on hydrogen peroxide. The process is characterized by cleaner production, high efficiency, and waste minimization. Optimization of process conditions, selection of equipment, and experiment of recycle of waste acid are carried out. The process design is realized in consideration of several aspects such as operation, material, equipment design and safety. An industrialized process flowsheet is developed according to experiment. A pilot testing is carried out to confirm the lab results. Process design of chlorine dioxide production based on hydrogen peroxide is realized.

  9. Green synthesis of nanosilver as a sensor for detection of hydrogen peroxide in water.

    Science.gov (United States)

    Shukla, Vineet K; Yadav, Raghvendra S; Yadav, Poonam; Pandey, Avinash C

    2012-04-30

    Present "green" synthesis is an efficient, easy-going, fast, renewable, inexpensive, eco-friendly and non-toxic approach for nanosilver formation, which offers numerous benefits over physiochemical approaches. The X-ray diffraction (XRD) pattern suggests the formation and crystallinity of nanosilver. The average particle size of silver nanoparticles was 8.25±1.37 nm as confirmed by transmission electron microscopy (TEM). The UV-vis absorption spectrum shows a characteristic absorption peak of silver nanoparticles at 410 nm. FTIR confirms Azadirachtin as reducing and stabilizing agent for nanosilver formation. In addition, the nanosilver modified electrode (Ag/GC) exhibited an excellent electro-catalytic activity toward the reduction of hydrogen peroxide (H(2)O(2)). The produced nanosilver is stable and comparable in size. These silver nanoparticles show potential applications in the field of sensors, catalysis, fuel cells and nanodevices.

  10. A hydrogen peroxide electrochemical sensor based on silver nanoparticles decorated three-dimensional graphene

    Energy Technology Data Exchange (ETDEWEB)

    Zhan, Beibei; Liu, Changbing; Shi, Huaxia; Li, Chen; Wang, Lianhui [Key Laboratory for Organic Electronics and Information Displays (KLOEID), Nanjing University of Posts and Telecommunications, Nanjing 210023 (China); Huang, Wei, E-mail: iamxcdong@njtech.edu.cn, E-mail: iamwhuang@njtech.edu.cn; Dong, Xiaochen, E-mail: iamxcdong@njtech.edu.cn, E-mail: iamwhuang@njtech.edu.cn [Key Laboratory for Organic Electronics and Information Displays (KLOEID), Nanjing University of Posts and Telecommunications, Nanjing 210023 (China); Jiangsu-Singapore Joint Research Center for Organic/Bio-Electronics and Information Displays and Institute of Advanced Materials (IAM), Nanjing Tech University, 30 South Puzhu Road, Nanjing 211816 (China)

    2014-06-16

    A facile strategy has been developed to synthesize sliver nanoparticles (Ag NPs) decorated three-dimensional graphene (3DG) through hydrothermal process. The AgNPs-3DG composites are directly fabricated into a free standing sensing electrode for electrochemical detection of hydrogen peroxide (H{sub 2}O{sub 2}) in phosphate buffered solutions. Various techniques equipments including scanning electron microscopy, X-ray diffraction, and Raman spectroscopy are used to characterize the morphology and structure of the as-prepared composite. The electrochemical experiments reveal the AgNPs-3DG based biosensor exhibits fast amperometric sensing, low detection limitation, wide linear responding range, and perfect selectivity for non-enzyme H{sub 2}O{sub 2} detection, indicating the well synergistic effect of Ag NPs high electrocatalytic activity and 3DG high conductivity and large surface area.

  11. Reduction of pollutants and disinfection of industrial wastewater by an integrated system of copper electrocoagulation and electrochemically generated hydrogen peroxide.

    Science.gov (United States)

    Barrera-Díaz, Carlos E; Frontana-Uribe, Bernardo A; Roa-Morales, Gabriela; Bilyeu, Bryan W

    2015-01-01

    The objective of this study was to evaluate the effect of copper electrocoagulation and hydrogen peroxide on COD, color, turbidity, and bacterial activity in a mixed industry wastewater. The integrated system of copper electrocoagulation and hydrogen peroxide is effective at reducing the organic and bacterial content of industrial wastewater. The copper electrocoagulation alone reduces COD by 56% in 30 min at pH 2.8, but the combined system reduces COD by 78%, biochemical oxygen demand (BOD5) by 81%, and color by 97% under the same conditions. Colloidal particles are flocculated effectively, as shown by the reduction of zeta potential and the 84% reduction in turbidity and 99% reduction in total solids. Additionally, the total coliforms, fecal coliforms, and bacteria are all reduced by 99%. The integrated system is effective and practical for the reduction of both organic and bacterial content in industrial wastewater.

  12. Green synthesis of nanosilver as a sensor for detection of hydrogen peroxide in water

    Energy Technology Data Exchange (ETDEWEB)

    Shukla, Vineet K., E-mail: vineet2shukla@gmail.com [Nanotechnology Application Centre, Faculty of Science, University of Allahabad, Allahabad 211002 (India); Department of Physics, Faculty of Science, University of Allahabad, Allahabad 211002 (India); Yadav, Raghvendra S. [Nanotechnology Application Centre, Faculty of Science, University of Allahabad, Allahabad 211002 (India); Yadav, Poonam [National Physical Laboratory, Dr. K. S. Krishnan Marg, New Delhi 110012 (India); Pandey, Avinash C. [Nanotechnology Application Centre, Faculty of Science, University of Allahabad, Allahabad 211002 (India)

    2012-04-30

    Highlights: Black-Right-Pointing-Pointer Present 'green' synthesis is an efficient, easy-going, fast, renewable, inexpensive, eco-friendly and non-toxic approach. Black-Right-Pointing-Pointer TEM shows average particle size of 8.25 {+-} 1.37 nm of synthesized nanosilver, giving UV-vis absorption at 410 nm. Black-Right-Pointing-Pointer FTIR confirms Azadirachtin as reducing and stabilizing agent for nanosilver formation (stability up to three months). Black-Right-Pointing-Pointer The nanosilver modified electrode (Ag/GC) exhibited an excellent electro-catalytic activity toward the reduction of hydrogen peroxide (H{sub 2}O{sub 2}). Black-Right-Pointing-Pointer The recovery percentage of H{sub 2}O{sub 2} in water is 92-105%, which is applicable for sensors and water/waste water plants. - Abstract: Present 'green' synthesis is an efficient, easy-going, fast, renewable, inexpensive, eco-friendly and non-toxic approach for nanosilver formation, which offers numerous benefits over physiochemical approaches. The X-ray diffraction (XRD) pattern suggests the formation and crystallinity of nanosilver. The average particle size of silver nanoparticles was 8.25 {+-} 1.37 nm as confirmed by transmission electron microscopy (TEM). The UV-vis absorption spectrum shows a characteristic absorption peak of silver nanoparticles at 410 nm. FTIR confirms Azadirachtin as reducing and stabilizing agent for nanosilver formation. In addition, the nanosilver modified electrode (Ag/GC) exhibited an excellent electro-catalytic activity toward the reduction of hydrogen peroxide (H{sub 2}O{sub 2}). The produced nanosilver is stable and comparable in size. These silver nanoparticles show potential applications in the field of sensors, catalysis, fuel cells and nanodevices.

  13. Antioxidant and anti-lipid peroxidation activities of Tamarindus indica seed coat in human fibroblast cells.

    Science.gov (United States)

    Nakchat, Oranuch; Meksuriyen, Duangdeun; Pongsamart, Sunanta

    2014-02-01

    Antioxidant activity and total phenolic content of tamarind seed coat extracts (TSCEs) were compared between the two extracts using boiling-water (TSCE-W) and 70% ethanol (TSCE-E) for extraction. TSCE-W, consisting of the highest phenolic content, possessed 2,2-diphenyl-1 -picrylhydrazyl (DPPH) radical scavenging and anti-lipid peroxidation activities much higher than TSCE-E and Trolox. Additionally, both TSCEs also exhibited superoxide anion and hydrogen peroxide scavenging activities higher than Trolox and BHA. Anti-lipid peroxidation and cytotoxicity of TSCE-W were also studied in human foreskin fibroblast CCD-1064Sk cells. Cytotoxic effect was not observed when exposed to TSCE-W up to 1 mg/mL for 12-48 h. However, TSCE-W significantly attenuated lipid peroxidation in H202-damaged cells. HPLC analysis showed the presence of (+)-catechin, (-)-epicatechin, and procyanidin B2 in TSCE-W, which could be responsible for antioxidant and anti-lipid peroxidation activities. The results suggest that an inexpensive and simple boiling-water extraction of TSCE-W may provide a valuable natural antioxidant source having anti-lipid peroxidation for health food additives, nutraceuticals as well as cosmeceuticals.

  14. Artificial photosynthesis for production of hydrogen peroxide and its fuel cells.

    Science.gov (United States)

    Fukuzumi, Shunichi

    2016-05-01

    The reducing power released from photosystem I (PSI) via ferredoxin enables the reduction of NADP(+) to NADPH, which is essential in the Calvin-Benson cycle to make sugars in photosynthesis. Alternatively, PSI can reduce O2 to produce hydrogen peroxide as a fuel. This article describes the artificial version of the photocatalytic production of hydrogen peroxide from water and O2 using solar energy. Hydrogen peroxide is used as a fuel in hydrogen peroxide fuel cells to make electricity. The combination of the photocatalytic H2O2 production from water and O2 using solar energy with one-compartment H2O2 fuel cells provides on-site production and usage of H2O2 as a more useful and promising solar fuel than hydrogen. This article is part of a Special Issue entitled Biodesign for Bioenergetics--The design and engineering of electronc transfer cofactors, proteins and protein networks, edited by Ronald L. Koder and J.L. Ross Anderson.

  15. Development of Pillared Clays for Wet Hydrogen Peroxide Oxidation of Phenol and Its Application in the Posttreatment of Coffee Wastewater

    Directory of Open Access Journals (Sweden)

    Nancy R. Sanabria

    2012-01-01

    Full Text Available This paper focuses on the use of pillared clays as catalysts for the Fenton-like advanced oxidation, specifically wet hydrogen peroxide catalytic oxidation (WHPCO. This paper discusses the limitations on the application of a homogeneous Fenton system, development of solid catalysts for the oxidation of phenol, advances in the synthesis of pillared clays, and their potential application as catalysts for phenol oxidation. Finally, it analyzes the use of pillared clays as heterogeneous Fenton-like catalysts for a real wastewater treatment, emphasizing the oxidation of phenolic compounds present in coffee wastewater. Typically, the wet hydrogen peroxide catalytic oxidation in a real effluent system is used as pretreatment, prior to biological treatment. In the specific case of coffee wet processing wastewater, catalytic oxidation with pillared bentonite with Al-Fe is performed to supplement the biological treatment, that is, as a posttreatment system. According to the results of catalytic activity of pillared bentonite with Al-Fe for oxidation of coffee processing wastewater (56% phenolic compounds conversion, 40% selectivity towards CO2, and high stability of active phase, catalytic wet hydrogen peroxide oxidation emerges as a viable alternative for management of this type of effluent.

  16. Plutonium(IV) peroxide formation in nitric medium and kinetics Pu(VI) reduction by hydrogen peroxide

    International Nuclear Information System (INIS)

    Reduction of plutonium (VI) to Pu(IV) with hydrogen peroxide is a step in industrial processes used to purify plutonium nitrate solutions. This operation must be carefully controlled, in order to avoid any formation of the Pu(IV) peroxide green precipitate and to obtain exclusively Pu(IV). This led us to study the acidity and Pu and H2O2 concentrations influences on the precipitate appearance and to perform a Pu(VI) reduction kinetic study on a wide range of acidities ([HNO3]: 0.5 to 8 M), plutonium concentrations ([Pu(VI)]: 0.1 to 0.8 M) and [H2O2]/[Pu(VI)] ratio (from 1 to 8). Thus, the domain of Pu(IV) peroxide formation and the reactional paths were established. With the exception of 0.5 M nitric acid medium, the kinetic curves show two distinct regims: the first one corresponds to an induction period where the Pu(VI) concentration doesn't change, the second corresponds to a linear decrease of Pu(VI). An increase of the temperature greatly accelerates the Pu(VI) reduction rate while [H2O2]/[Pu(VI)] has almost no influence. The Pu(VI) total reduction time decreases when initial concentration of plutonium increases. By increasing nitric acid concentration from 0.5 M to 6 M, the total Pu(VI) reduction time decreases. This time increases when [HNO3] varies from 6 M to 8 M. (orig.)

  17. Determination of active oxygen content in rare earth peroxides; Determinacao de oxigenio ativo em peroxidos de terras raras

    Energy Technology Data Exchange (ETDEWEB)

    Queiroz, Carlos A.S.; Abrao, Alcidio

    1993-12-31

    The content of active oxygen in rare earth peroxides have been determined after the dissolution of the samples with hydrocloridic acid in the presence of potassium iodide. The free generated iodine is titrated with sodium thiosulfate using starch as indicator. The oxidation of iodide to the free iodine indicates the presence of a higher valence state rare earth oxide, until now specifically recognized for the oxides of cerium (Ce O{sub 2}), praseodymium (Pr{sub 6} O{sub 1}1) and terbium (TB{sub 4} O{sub 7}). recently the authors synthesized a new series of rare earth compounds, the peroxides. These new compounds were prepared by precipitating the rare earth elements complexed with carbonate ion by addition of hydrogen peroxide. the authors demonstrated that all rare earth elements, once solubilized by complexing with carbonate ion, are quantitatively precipitated as peroxide by addition of hydrogen peroxide. (author) 3 refs., 1 tab.

  18. Homolytic Cleavage of Both Heme-Bound Hydrogen Peroxide and Hydrogen Sulfide Leads to the Formation of Sulfheme.

    Science.gov (United States)

    Arbelo-Lopez, Hector D; Simakov, Nikolay A; Smith, Jeremy C; Lopez-Garriga, Juan; Wymore, Troy

    2016-08-01

    Many heme-containing proteins with a histidine in the distal E7 (HisE7) position can form sulfheme in the presence of hydrogen sulfide (H2S) and a reactive oxygen species such as hydrogen peroxide. For reasons unknown, sulfheme derivatives are formed specifically on solvent-excluded heme pyrrole B. Sulfhemes severely decrease the oxygen-binding affinity in hemoglobin (Hb) and myoglobin (Mb). Here, use of hybrid quantum mechanical/molecular mechanical methods has permitted characterization of the entire process of sulfheme formation in the HisE7 mutant of hemoglobin I (HbI) from Lucina pectinata. This process includes a mechanism for H2S to enter the solvent-excluded active site through a hydrophobic channel to ultimately form a hydrogen bond with H2O2 bound to Fe(III). Proton transfer from H2O2 to His64 to form compound (Cpd) 0, followed by hydrogen transfer from H2S to the Fe(III)-H2O2 complex, results in homolytic cleavage of the O-O and S-H bonds to form a reactive thiyl radical (HS(•)), ferryl heme Cpd II, and a water molecule. Subsequently, the addition of HS(•) to Cpd II, followed by three proton transfer reactions, results in the formation of a three-membered ring ferric sulfheme that avoids migration of the radical to the protein matrix, in contrast to that in other peroxidative reactions. The transformation of this three-membered episulfide ring structure to the five-membered thiochlorin ring structure occurs through a significant potential energy barrier, although both structures are nearly isoenergetic. Both three- and five-membered ring structures reveal longer NB-Fe(III) bonds compared with other pyrrole nitrogen-Fe(III) bonds, which would lead to decreased oxygen binding. Overall, these results are in agreement with a wide range of experimental data and provide fertile ground for further investigations of sulfheme formation in other heme proteins and additional effects of H2S on cell signaling and reactivity. PMID:27357070

  19. HYDROGEN PEROXIDE BLEACHING OF CMP PULP USING MAGNESIUM HYDROXIDE

    Directory of Open Access Journals (Sweden)

    Farhad Zeinaly

    2009-11-01

    Full Text Available Conventional bleaching of hardwood CMP pulp with magnesium hydroxide (Mg(OH2 show significant benefits over bleaching with sodium hydroxide (NaOH under various conditions. Magnesium hydroxide bleaching generate higher optical properties, higher pulp yield and lower effluent COD at the same chemical charge, but the physical properties were found to be similar for both processes. The initial freeness of the bleached pulps and refining value to reach a target freeness (about 350 ml. CSF were more for the Mg(OH2-based process. The residual peroxide of filtrate from the Mg(OH2-based process was very high as compared to conventional bleaching.

  20. AC催化H2O2处理水中有机污染物的研究进展%Progress on Degradation of Organic Pollutants in Wastewater Through Activated Carbon-Hydrogen Peroxide

    Institute of Scientific and Technical Information of China (English)

    张娜; 王磊; 丰娇; 吴耀国

    2013-01-01

    Activated carbon (AC) can catalyze hydrogen peroxide (H2O2) to generate hydroxyl radicals (· OH).The physical and chemical properties of AC are not only in favor of the reactant molecule diffusion and adsorption but also the catalytic oxidation reaction.The synergistic effect of AC's adsorption and catalysis enhance the ability of organic contaminants removal by AC-H2O2.The AC-H2 O2 system in removal of organic in wastewater was reviewed in detail.The effects of AC-H2 O2,AC-Fe2+-H2 O2 (-microwave/UV) and the system which AC is used as the heterogeneous Fenton catalyst support were analyzed,meanwhile,their reaction mechanisms were discussed.Moreover,some problems which exist presently were put forward,and the prospect of AC-H2O2 system was made.%活性炭(AC)优良的物化性质不仅利于反应物分子的扩散与吸附,还利于过氧化氢(H2O2)催化分解产生羟基自由基(·OH),进而促进氧化反应的进行,在AC-H2O2体系中,二者甚至可以产生协同效应,增强难降解有机污染物的去除功效.综述了AC催化H2O2处理水中有机污染物的研究进展,分析了AC-H2 O2、AC-Fe2+-H2O2(-微波/UV),以及AC作为载体的非均相Fenton催化剂体系影响因素,探讨了它们的反应机制,并总结与展望了AC-H2 O2体系存在的问题及发展前景.

  1. Dissolution kinetics of U3Si2 particles in alkaline hydrogen peroxide

    International Nuclear Information System (INIS)

    Nonproliferation concerns leading to the conversion from high- to low-enriched uranium sparked interest in U3Si2 dispersion targets as an option for 99Mo production. Dissolution of irradiated targets is an important step in recovering fission-product 99Mo. Alkaline hydrogen peroxide solutions dissolved U3Si2 particles in an open batch reactor; samples were analyzed for total peroxide and uranium concentrations as functions of time and temperature. Dissolution rates are highest at 1 to 1.5 M NaOH and change little for initial base concentrations from 0.5 to 2.5 M NaOH, indicating relatively robust process conditions. Uranium dissolution rates depend most strongly on the equilibrium concentration of the peroxyl ion (O2H-), an equilibrium product of hydrogen peroxide (H2O2) and hydroxyl ion (OH-). Temperature and equilibrium concentrations of O2H- and OH- are included in a uranium dissolution rate model

  2. Use of hydrogen peroxide treatment and crystal violet agar plates for selective recovery of bacteriophages from natural environments

    Energy Technology Data Exchange (ETDEWEB)

    Asghari, A.; Farrah, S.R.; Bitton, G. (Univ. of Florida, Gainesville (United States))

    1992-04-01

    Hydrogen peroxide inactivated bacteriophages and bacteria at different rates. A concentration of 0.1% hydrogen peroxide reduced the numbers of several bacteria by an average of 94% but caused an average of 25% inactivation in the numbers of bacteriophages tested. Treating natural samples with hydrogen peroxide selectively reduced the indigenous bacterial flora and permitted better visualization of plaques of lawns of Escherichia coli C-3000. In some cases indigenous gram-positive bacteria were relatively resistant to hydrogen peroxide, but their growth could be limited by incorporation of crystal violet into the bottom agar used for plaque assays. The use of hydrogen peroxide treatment and crystal violet-containing plates permitted recovery of more phages from natural samples than did other procedures, such as chloroform pretreatment or the use of selective plating agar such as EC medium.

  3. Rational Design of an α-Ketoamide-Based Near-Infrared Fluorescent Probe Specific for Hydrogen Peroxide in Living Systems.

    Science.gov (United States)

    Xie, Xilei; Yang, Xiu'e; Wu, Tianhong; Li, Yong; Li, Mengmeng; Tan, Qi; Wang, Xu; Tang, Bo

    2016-08-16

    Hydrogen peroxide, an important biomolecule, receives earnest attention because of its physiological and pathological functions. In this Article, we present the rational design, characterization, and biological application of a mitochondria-targetable NIR fluorescent sensor, Mito-NIRHP, for hydrogen peroxide visualization. Mito-NIRHP utilizes a unique reaction switch, α-ketoamide moiety, to turn on a highly specific, sensitive, and rapid fluorescence response toward hydrogen peroxide coupled with the intramolecular charge transfer strategy. Mito-NIRHP is competent to track endogenously produced hydrogen peroxide in both living cells and living animals. In addition, utilizing Mito-NIRHP, overgeneration of hydrogen peroxide during ischemia-reperfusion injury was directly visualized at both cell and organ levels.

  4. Efficacy of formalin, hydrogen-peroxide, and sodium-chloride on fungal-infected rainbow-trout eggs

    Science.gov (United States)

    Schreier, T.M.; Rach, J.J.; Howe, G.E.

    1996-01-01

    Antifungal agents are essential for the maintenance of healthy stocks of fish and their eggs in intensive aquaculture operations. In the usa, formalin is the only fungicide approved for use in fish culture, however, hydrogen peroxide and sodium chloride have been granted low regulatory priority drug status by the united states food and drug administration (fda) and their use is allowed. We evaluated the efficacy of these fungicides for controlling fungal infections on rainbow trout eggs. A pilot study was conducted to determine the minimum water flow rate required to administer test chemicals accurately in heath incubators. A minimum water flow rate of 7.6 1 min(-1) was necessary to maintain treatment concentrations during flow-through chemical exposures, the antifungal activity of formalin, hydrogen peroxide, and sodium chloride was evaluated by treating uninfected and 10% fungal-infected (saprolegnia parasitica) rainbow trout eggs (oncorhynchus mykiss) for 15 min every other day until hatch. There were no significant differences among treatments in percent hatch or final infection for uninfected eggs receiving prophylactic chemical treatments, eggs of the negative control group (uninfected and untreated) had a mean hatch exceeding 86%, all chemical treatments conducted on the infected egg groups controlled the spread of fungus and improved hatching success compared with the positive control groups (infected and untreated), formalin treatments of 1000 and 1500 mu l 1(-1) and hydrogen peroxide treatments of 500 and 1000 mu l 1(-1) were the most effective. Sodium chloride treatments of 30000 mg 1(-1) improved fry hatch, but the compound was less effective at inhibiting fungal growths compared with hydrogen peroxide and formalin treatments.

  5. Transcriptional analysis of Mycobacterium fortuitum cultures upon hydrogen peroxide treatment using the novel standard rrnA-P1

    Directory of Open Access Journals (Sweden)

    Rebollo María

    2008-06-01

    Full Text Available Abstract Background The ability of an intracellular pathogen to establish infection depends on the capacity of the organism to survive and replicate inside the host. Mycobacterium fortuitum is a bacteria that contains genes involved in the detoxification of the oxygen reactive species such as those produced by the host during the infection. In this work, we investigate the effects of hydrogen peroxide on the transcription and expression of these genes by developing a real time quantitative PCR technique (qRT-PCR using the ribosomal promoter region (rrnA-P1 as reference product for quantification of the mRNA levels. Results M. fortuitum cultures were treated with different hydrogen peroxide concentrations (0.02 to 20 mM during several periods of time (30 to 120 minutes. The activity of the enzymes KatGII and SodA, and the transcription of corresponding genes were evaluated. The transcriptional regulator furAII gene was also studied. The ribosomal promoter region rrnA-P1 was validated as referential product under the stress conditions checked by qRT-PCR. Minor changes were observed under the conditions tested except when bacteria were incubated in the presence of 20 mM hydrogen peroxide. Under those conditions, the levels of transcription of the three genes under study increased at 30 minutes of treatment. The viability of the bacteria was not influenced under the conditions tested. Conclusion In this work, we have quantified transcriptional responses to stress suggesting that, the opportunistic pathogen M. fortuitum is more resistant and differs in behaviour in the presence of hydrogen peroxide, when compared to the major pathogen Mycobacterium tuberculosis and the saprophyte Mycobacterium smegmatis. Besides, we demonstrate the mycobacterial non-coding region rrnA-P1 to be a suitable reference product in the analysis of qRT-PCR transcriptional data of M. fortuitum.

  6. Transcriptional analysis of Mycobacterium fortuitum cultures upon hydrogen peroxide treatment using the novel standard rrnA-P1

    Science.gov (United States)

    Núñez, María Carmen; Menéndez, María Carmen; Rebollo, María José; García, María J

    2008-01-01

    Background The ability of an intracellular pathogen to establish infection depends on the capacity of the organism to survive and replicate inside the host. Mycobacterium fortuitum is a bacteria that contains genes involved in the detoxification of the oxygen reactive species such as those produced by the host during the infection. In this work, we investigate the effects of hydrogen peroxide on the transcription and expression of these genes by developing a real time quantitative PCR technique (qRT-PCR) using the ribosomal promoter region (rrnA-P1) as reference product for quantification of the mRNA levels. Results M. fortuitum cultures were treated with different hydrogen peroxide concentrations (0.02 to 20 mM) during several periods of time (30 to 120 minutes). The activity of the enzymes KatGII and SodA, and the transcription of corresponding genes were evaluated. The transcriptional regulator furAII gene was also studied. The ribosomal promoter region rrnA-P1 was validated as referential product under the stress conditions checked by qRT-PCR. Minor changes were observed under the conditions tested except when bacteria were incubated in the presence of 20 mM hydrogen peroxide. Under those conditions, the levels of transcription of the three genes under study increased at 30 minutes of treatment. The viability of the bacteria was not influenced under the conditions tested. Conclusion In this work, we have quantified transcriptional responses to stress suggesting that, the opportunistic pathogen M. fortuitum is more resistant and differs in behaviour in the presence of hydrogen peroxide, when compared to the major pathogen Mycobacterium tuberculosis and the saprophyte Mycobacterium smegmatis. Besides, we demonstrate the mycobacterial non-coding region rrnA-P1 to be a suitable reference product in the analysis of qRT-PCR transcriptional data of M. fortuitum. PMID:18565220

  7. Selective formation of hydrogen peroxide by oxygen reduction on TiO2 nanotubes in alkaline media

    International Nuclear Information System (INIS)

    Graphical abstract: Hydrogen peroxide (H2O2) is widely used in the chemical industry and environmental protection. The oxygen reduction in alkaline solution using TiO2 nanotube array catalyst showed a unique electrochemical behavior of two well-separated 2-electron O2 reduction peaks and formation of H2O2. TiO2 nanotube array electrodes are of interest in a wide range of applications and the possibility to fine-tune reactivity to avoid or to promote peroxide formation will be of considerable use and benefits. - Abstract: The oxygen electrochemical reduction at nitrogen treated TiO2 nanotubes electrode shows distinctive and well-separated 2-electrons reduction peaks. The oxygen reduction was investigated in alkaline solution at titanium oxide nanotube (TON) arrays fabricated by anodizing of titanium foil in hydrogen fluoride solution followed by annealing at 450 °C in nitrogen (TON-N2) atmosphere. The morphology of the arrays was characterized by SEM and the electrochemical behavior was studied by cyclic voltammetry in potassium ferrocyanide and alkaline solutions. The treated TON arrays showed a significant enhancement in conductivity and in the activity for reduction of O2 in alkaline media in comparison to the data of plain TiO2. TON arrays annealed in N2 showed a unique electrochemical behavior of two well-resolved 2-electrons O2 reduction peaks in contrast to TON arrays annealed air, which only showed a single reduction peak at more negative potential. At TON-N2 arrays, hydrogen peroxide was detected as the main product during the first reduction. The switch in mechanism is proposed to be due to the presence of oxygen vacancies at the surface of titania nanotube arrays. The finding is of a high importance for the selective production of hydrogen peroxide by electrochemical reduction of oxygen in alkaline media using TiO2 nanotubes electrode

  8. Selective suppression of harmful cyanobacteria in an entire lake with hydrogen peroxide

    NARCIS (Netherlands)

    H.C.P. Matthijs; P.M. Visser; B. Reeze; J. Meeuse; P.C. Slot; G. Wijn; R. Talens; J. Huisman

    2012-01-01

    Although harmful cyanobacteria form a major threat to water quality, few methods exist for the rapid suppression of cyanobacterial blooms. Since laboratory studies indicated that cyanobacteria are more sensitive to hydrogen peroxide (H2O2) than eukaryotic phytoplankton, we tested the application of

  9. Solvent-dependent regioselective oxidation of trans-chalcones using aqueous hydrogen peroxide

    Energy Technology Data Exchange (ETDEWEB)

    Peng, Wang; Jiabin, Yang; Lushen, Li, E-mail: jimin@seu.edu.cn [Southeast University, Nanjing (China). School of Biological Science and Medical Engineering; Jin, Cai; Chunlong, Sun; Min, Ji [Southeast University, Nanjing (China). School of Chemistry and Chemical Engineering

    2013-03-15

    A novel method for regioselective oxidation of trans-chalcones with hydrogen peroxide in acetonitrile to afford cinnamic acids is reported. Only trans-b-arylacrylic acids were observed. A wide range of functionalized products can be effectively produced from various chalcones in good to excellent yields. (author)

  10. Electrodeposited nanostructured MnO2 for non-enzymatic hydrogen peroxide sensing

    International Nuclear Information System (INIS)

    Electrodeposited MnO2 nanostructure was synthesized on indium tin oxide coated glass electrode by cyclic voltammetry. The as obtained samples were subsequently characterized by atomic force microscopy and their electro-catalytic response towards hydrogen peroxide in alkaline medium of 0.1M NaOH was studied using cyclic voltammetry and amperometry

  11. Study on a hydrogen peroxide biosensor based on horseradish peroxidase/GNPs-thionine/chitosan

    International Nuclear Information System (INIS)

    Highlights: ► Glutaraldehyde was used as the bridge linking agent to covalently bonded thionine in chitosan, which is more stable and could effectively prevalent leakage of the electronic mediator. ► The effect of GNPs adsorbed HRP was first accurately characterized by bio-layer interferometry using the ForteBio Octer system. ► The application of self-assembly technology increases the biosensor stability. - Abstract: A novel hydrogen peroxide biosensor based on horseradish peroxidase/GNPs-thionine/chitosan has been developed. Gold nanoparticles fixed with horseradish peroxidase were adsorbed on glassy carbon electrode by the chitosan which cross-linked with the electron mediator of horseradish peroxidase as the bridge linking agent. The assembly procedures were monitored by UV–visible spectral scanning, bio-layer interferometry, cyclic voltammetric and alternating current impedance. The chronoamperometry was used to measure hydrogen peroxide. The hydrogen peroxide biosensor linear range of detection is 1 × 10−7–1 × 10−4 mol/L, detection limit up to 5.0 × 10−8 mol/L. Moreover the stability, reproducibility and selectivity of the biosensor were also studied and the results confirmed that the biosensor exhibit fast response to hydrogen peroxide and possess high sensitivity, good reproducibility and long-term stability.

  12. MINERALIZATION OF A SORBED POLYCYCLIC AROMATIC HYDROCARBON IN TWO SOILS USING CATALYZED HYDROGEN PEROXIDE. (R826163)

    Science.gov (United States)

    Hydrogen peroxide (H2O2) catalyzed by soluble iron or naturally occurring soil minerals, (i.e., modified Fenton's reagent) was investigated as a basis for mineralizing sorbed and NAPL-phase benzo[a]pyrene (BaP), a hydrophobic and toxic polycyclic a...

  13. A dissolution study of cobalt oxide by hydrogen peroxide in boric acid solution

    International Nuclear Information System (INIS)

    A dissolution study of CoO (cobaltous oxide) by hydrogen peroxide was carried out in boric acid solution at 60degC. The chemical species of dissolved cobalt are Co+2 and Co(OH)+, being equilibrated with Co(OH)2, and the concentration ratio of the both ion species is determined by pH of the solution. Hydrogen peroxide accelerates the dissolution of CoO, which occures during it is decomposed. In the case where the solution is oxygenated, Co(OH)2 in the solution and/or covering the CoO crystal surface as a layer becomes Co2O3 remarkably less soluble than CoO and the reaction rate becomes somewhat slow with decreasing pH. On the basis of the results, it could be concluded that, in order to decrease the radiation dose rate on the personnel and the Co58 inventory in primary coolant system at the minimum in the practical use, the Co58 removal procedures must be consisted of: 1) The first step in that addition of small amount of hydrogen peroxide and oxygen removal are consevtively performed several times for accelerating the dissolution of Co58 2) The second step in that only addition of relatively larger amount of hydrogen peroxide is performed for repressing the dissolution of Co58. (Author)

  14. Role of hydrogen peroxide during the interaction between the hemibiotrophic fungal pathogen Septoria tritici and wheat

    NARCIS (Netherlands)

    Shetty, N.P.; Mehrabi, R.; Lütken, H.; Haldrup, A.; Kema, G.H.J.

    2007-01-01

    Hydrogen peroxide (H2O2) is reported to inhibit biotrophic but benefit necrotrophic pathogens. Infection by necrotrophs can result in a massive accumulation of H2O2 in hosts. Little is known of how pathogens with both growth types are affected (hemibiotrophs). The hemibiotroph, Septoria tritici, inf

  15. Epoxidation of Alkenes with Aqueous Hydrogen Peroxide and Quaternary Ammonium Bicarbonate Catalysts

    DEFF Research Database (Denmark)

    Mielby, Jerrik Jørgen; Kegnæs, Søren

    2013-01-01

    A range of solid and liquid catalysts containing bicarbonate anions were synthesised and tested for the epoxidation of alkenes with aqueous hydrogen peroxide. The combination of bicarbonate anions and quaternary ammonium cations opens up for new catalytic systems that can help to overcome challen...

  16. Electroactive gate materials for a hydrogen peroxide sensitive E-MOSFET

    NARCIS (Netherlands)

    Anh, Dam T.V.; Olthuis, W.; Bergveld, P.

    2002-01-01

    Describes the detection principle of a hydrogen peroxide sensor based on the electrolyte metal oxide semiconductor field effect transistor (EMOSFET) and possibilities of using different types of redox materials as the gate material for the sensor with respect to the sensitivity and detection limit.

  17. Effect of hydrogen peroxide and thiourea on fluorescence and tuberization of potato (Solanum tuberosum L.

    Directory of Open Access Journals (Sweden)

    Mani F.

    2012-08-01

    Full Text Available The aim of this study is to determine the effect of hydrogen peroxide and thiourea on potato crop (quantum yield (Fv/ Fm, chlorophyll content, tuber diameter, tuber number and total tuber yield. The concentrations of these two chemicals are hydrogen peroxide: 0, 20, 40, 60 and 80 mM, and thiourea : 0, 250, 500, 750 and 1000 mM. The experiment was conducted in the farm of Chott-Mariem Institute during three months using variety 'Spunta' and arranged in a completely randomized block with three replications. Results show that there is no significant difference in tuber diameter between treatments and among the same treatment. However, tuber yield is significantly increased by 20 % by thiourea (250 mM. Maximum total yield was obtained at this concentration (810 g/plant. In addition, application of thiourea (500 and 750 mM results in a significantly higher number of tubers number (5.7 and 5.2 respectively. In contrast, treatment with hydrogen peroxide brings about similar tuber yields. Although, application of hydrogen peroxide at low concentration (20 mM, decreases chlorophyll content and stresses plants, application of thiourea increases chlorophyll content, and improve quantum yield especially when it is applied at 250 mM.

  18. First Principles Modeling of the Performance of a Hydrogen-Peroxide-Driven Chem-E-Car

    Science.gov (United States)

    Farhadi, Maryam; Azadi, Pooya; Zarinpanjeh, Nima

    2009-01-01

    In this study, performance of a hydrogen-peroxide-driven car has been simulated using basic conservation laws and a few numbers of auxiliary equations. A numerical method was implemented to solve sets of highly non-linear ordinary differential equations. Transient pressure and the corresponding traveled distance for three different car weights are…

  19. Environmental meticillin-resistant Staphylococcus aureus (MRSA) disinfection using dry-mist-generated hydrogen peroxide

    DEFF Research Database (Denmark)

    Bartels, M.D.; Kristoffersen, K.; Slotsbjerg, T.;

    2008-01-01

    Meticillin-resistant Staphylococcus aureus (MRSA) is a major problem in hospitals worldwide. Hand hygiene is recognised as crucial in limiting the spread of MRSA but less is known about the role of MRSA reservoirs in the inanimate hospital environment. We evaluated the effect of hydrogen peroxide...

  20. Explodability and detonability of mixtures of hydrogen peroxide and organic matter

    NARCIS (Netherlands)

    Heemskerk, A.H.; Scholtes, J.H.G.

    1995-01-01

    The explosive properties of mixtures of hydrogen peroxide and isopropanol were determined The mixtures appear to detonate in a well-defined range of concentrations and show extremely fast reactions in an adjacent range of concentrations if initiated by shock wave stimuli. The upper boundary of organ

  1. HYDROGEN PEROXIDE FORMATION FROM THE PHOTOOXIDATION OF FORMALDEHYDE AND ITS PRESENCE IN RAINWATER

    Science.gov (United States)

    The photooxidation of formaldehyde with sunlamps (E(max) = 3100 A) produces hydrogen peroxide (H2O2) at varying concentrations depending upon the amount of water vapor present. It is postulated that the variable production of H2O2 is a result of condensation on the reactor surfac...

  2. Nectar defense and hydrogen peroxide in floral nectar of Cucurbita pepo

    Directory of Open Access Journals (Sweden)

    Daniele Nocentini

    2015-03-01

    Full Text Available This study was carried out to investigate some similarities between the nectaries of Nicotiana sp. and Cucurbita pepo, such as starch accumulation in the nectary parenchyma, changes in nectary color during maturation, and the production of a large quantity of sucrose-dominant nectar. The concentration of hydrogen peroxide in C. pepo floral nectar was determined in order to verify the presence of a defense mechanism similar to that found in Nicotiana sp. which protects nectar from yeast and bacteria proliferation. We also tested the eventual accumulation of antioxidants in the nectary of C. pepo as a protection against oxidative stress caused by hydrogen peroxide. The level of hydrogen peroxide found in the floral nectar of C. pepo was much lower than that found in Nicotiana sp. and the male flowers of Cucurbita had a higher concentration than the female flowers. The low oxidative stress induced by this level of hydrogen peroxide caused the accumulation of a low amount of lutein inside the plastoglobules which were contained in amyloplasts. Plastids of the C. pepo nectary are specialized in the accumulation of starch rather than antioxidants.

  3. Optimization study on the hydrogen peroxide pretreatment and production of bioethanol from seaweed Ulva prolifera biomass.

    Science.gov (United States)

    Li, Yinping; Cui, Jiefen; Zhang, Gaoli; Liu, Zhengkun; Guan, Huashi; Hwang, Hueymin; Aker, Winfred G; Wang, Peng

    2016-08-01

    The seaweed Ulva prolifera, distributed in inter-tidal zones worldwide, contains a large percentage of cellulosic materials. The technical feasibility of using U. prolifera residue (UPR) obtained after extraction of polysaccharides as a renewable energy resource was investigated. An environment-friendly and economical pretreatment process was conducted using hydrogen peroxide. The hydrogen peroxide pretreatment improved the efficiency of enzymatic hydrolysis. The resulting yield of reducing sugar reached a maximum of 0.42g/g UPR under the optimal pretreatment condition (hydrogen peroxide 0.2%, 50°C, pH 4.0, 12h). The rate of conversion of reducing sugar in the concentrated hydrolysates to bioethanol reached 31.4% by Saccharomyces cerevisiae fermentation, which corresponds to 61.7% of the theoretical maximum yield. Compared with other reported traditional processes on Ulva biomass, the reducing sugar and bioethanol yield are substantially higher. Thus, hydrogen peroxide pretreatment is an effective enhancement of the process of bioethanol production from the seaweed U. prolifera. PMID:27132221

  4. Mouthwashes with hydrogen peroxide are carcinogenic, but are freely indicated on the internet: warn your patients!

    Directory of Open Access Journals (Sweden)

    Alberto Consolaro

    2013-12-01

    Full Text Available It all began in Ancient Egypt where people used to bleach their teeth with antiseptic mouthwashes made of urea from human urine. Teeth harmony is promoted by expression of feelings, communication, a real window of the brain and its content! Tooth bleaching products are medicines, not cosmetics! Mouth washing with hydrogen peroxide is an illogical and dangerous procedure! Hydrogen peroxide must be used in one's mouth only when employed by a dentist who has been properly instructed to protect the mucosa, preventing it from receiving these products. How and for how long these products are going to be used require caution in order to avoid or decrease any adverse effects on the tissues. Many websites instruct people on how to purchase and prepare hydrogen peroxide so that it is used as an antiseptic mouthwash and tooth bleaching agent. Some websites even refer to dentists as "exploiters", accusing them of not instructing patients properly. In this article, we aim at providing evidence and information upon which dentists and assistants may base their thinking as well as their opinion and procedures regarding "the indiscriminate and free use of hydrogen peroxide in the mouth, on teeth and oral mucosa". Those websites, blogs and social network profiles trespass the limits of public trust and should be immediately sued by the government for committing a crime against public health.

  5. Kinetics of wet peroxide oxidation of phenol with a gold/activated carbon catalyst

    OpenAIRE

    Domínguez, Carmen M.; Quintanilla, Asunción; Casas, José Antonio; Rodríguez, Juan José

    2014-01-01

    Gold nanoparticles supported on activated carbon (Au/AC) have been tested in catalytic wet peroxide oxidation using phenol as target pollutant. In the current work, the effect of several operating conditions, including initial pH (3.5–10.5), catalyst load (0–6 g/L), initial phenol concentration (0.1–5 g/L), hydrogen peroxide dose (4–100% of the theoretical stoichiometric amount) and reaction temperature (50–80 °C) has been investigated. The results show that the Au/AC catalyst would be useful...

  6. Hydrogen peroxide modification enhances the ability of biochar (hydrochar) produced from hydrothermal carbonization of peanut hull to remove aqueous heavy metals: Batch and column tests

    Science.gov (United States)

    Experimental and modeling investigations were conducted to examine the effect of hydrogen peroxide treatment on hydrothermally produced biochar (hydrochar) from peanut hull to remove aqueous heavy metals. Characterization measurements showed that hydrogen peroxide modification increased the oxygen-c...

  7. Prostaglandins attenuate cardiac contractile dysfunction produced by free radical generation but not by hydrogen peroxide.

    Science.gov (United States)

    Zimmer, K M; Karmazyn, M

    1997-11-01

    The aim of this study was to examine and compare the potential influence of cyclooxygenase or lipoxygenase derived metabolites of arachidonic acid on myocardial injury produced either by a free radical generating system consisting of purine plus xanthine oxidase or that produced by hydrogen peroxide. A free radical generating system consisting of purine (2.3 mM) and xanthine oxidase (10 U/L) as well as hydrogen peroxide (75 microM) produced significant functional changes in the absence of either significant deficits in high energy phosphates or ultrastructural damage. Prostaglandin F2 alpha (30 nM) significantly attenuated both the negative inotropic effect of purine plus xanthine oxidase as well as the ability of the free radical generator to elevate diastolic pressure. An identical concentration of prostaglandin 12 (prostacyclin) significantly reduced diastolic pressure elevation only and had no effect on contractile depression. The salutary effects of the two PGs occurred in the absence of any inhibitory influence on superoxide anion generation produced by the purine and xanthine oxidase reaction. None of prostaglandins modulated the response to hydrogen peroxide. In addition, neither prostaglandin E2 nor leukotrienes exerted any effect on changes produced by either type of oxidative stress. A 5 fold elevation in the concentrations of free radical generators or hydrogen peroxide produced extensive injury as characterized by a virtual total loss in contractility, 400% elevation in diastolic pressure, ultrastructural damage and significant depletions in high energy phosphate content. None of these effects were modulated by eicosanoid treatment. Our results therefore demonstrate a selective ability of both prostaglandin F2 alpha and to a lesser extent prostacyclin, to attenuate dysfunction produced by purine plus xanthine oxidase but not hydrogen peroxide. It is possible that these eicosanoids may represent endogenous protective factors under conditions of enhanced

  8. Temperature response and durability characterization of an optical fiber sensor for the detection of hydrogen peroxide

    International Nuclear Information System (INIS)

    Hydrogen peroxide is a precursor to damage mechanisms in numerous applications; its monitoring is important and challenging. The effect of temperature on the performance and durability of a recently developed optical fiber sensors sensitive to the presence of hydrogen peroxide in low concentrations is investigated. The sensors are fabricated by immobilizing Prussian blue within a multilayer of electrostatically self-assembled polyelectrolytes. The sensing principle of this optical electrode relies on the change in the intensity of the reflected light when Prussian white is oxidized back to the blue state due to the presence of hydrogen peroxide. The amplitude of the intensity of the reflected light is found to vary with temperature in a quadratic fashion, but the characteristic response time which correlates with concentration remains constant. Thus the sensing device retains its abilities to determine and quantify the concentration of hydrogen peroxide in a liquid solution. Additionally, the degradation of these fiber sensors when subjected to high temperature is examined. Four optical fiber sensing devices were subjected to different testing conditions and a characterization protocol that included: measurement of the intensity of the cyanide stretch (2150 cm−1) via Raman micro spectroscopy; imaging with scanning electron microscopy; and measurement of the presence of iron ions using energy dispersive X-ray spectroscopy. The results show a gradual degradation of the sensing device as a result of progressive desorption of the polyelectrolyte multilayer structure that leads to leaching of the Prussian reagent. This degradation mechanism does not compromise the functionality of the device which is found sufficiently robust for multiple tests at high temperature. The simplicity of this sensing system combined with its relative robustness and reusability make it a good a good candidate for minimally intrusive and localized monitoring of hydrogen peroxide formation in

  9. Hydrogen peroxide mediates oxidant-dependent stimulation of arterial smooth muscle L-type calcium channels.

    Science.gov (United States)

    Chaplin, Nathan L; Amberg, Gregory C

    2012-05-01

    Changes in calcium and redox homeostasis influence multiple cellular processes. Dysregulation of these signaling modalities is associated with pathology in cardiovascular, neuronal, endocrine, and other physiological systems. Calcium and oxidant signaling mechanisms are frequently inferred to be functionally related. To address and clarify this clinically relevant issue in the vasculature we tested the hypothesis that the ubiquitous reactive oxygen molecule hydrogen peroxide mediates oxidant-dependent stimulation of cerebral arterial smooth muscle L-type calcium channels. Using a combinatorial approach including intact arterial manipulations, electrophysiology, and total internal reflection fluorescence imaging, we found that application of physiological levels of hydrogen peroxide to isolated arterial smooth muscle cells increased localized calcium influx through L-type calcium channels. Similarly, oxidant-dependent stimulation of L-type calcium channels by the vasoconstrictor ANG II was abolished by intracellular application of catalase. Catalase also prevented ANG II from increasing localized subplasmalemmal sites of increased oxidation previously associated with colocalized calcium influx through L-type channels. Furthermore, catalase largely attenuated the contractile response of intact cerebral arterial segments to ANG II. In contrast, enhanced dismutation of superoxide to hydrogen peroxide with SOD had no effect on ANG II-dependent stimulation of L-type calcium channels. From these data we conclude that hydrogen peroxide is important for oxidant-dependent regulation of smooth muscle L-type calcium channels and arterial function. These data also support the emerging concept of hydrogen peroxide as a biologically relevant oxidant second messenger in multiple cell types with a diverse array of physiological functions.

  10. Role of airway lactoperoxidase in scavenging of hydrogen peroxide damage in asthma

    Directory of Open Access Journals (Sweden)

    Al Obaidi Amina Hamed

    2007-01-01

    Full Text Available Hydrogen peroxide (H 2 O 2 that is mainly generated by neutrophils and eosinophils in asthma is known to be damaging to the airway and to contribute to airway inflammation. The purpose of the present study was to determine the contribution and the role of lactoperoxidase in scavenging airway hydrogen peroxide, in order to propose a therapeutic approach for asthma. The study was an open clinical trial. Twenty-five nonsmoking asthmatic patients were included in the study. Of them, 16 patients (64% were male and 9 (36% were female, with age ranging from 29 to 48 years (45.13 ± 4.6. Of the 25 patients included in the study, only 16 patients completed the study; and they were eligible for analyses. Exhaled breath condensate was collected from all patients at the time of entering the study; and 2, 4 and 8 weeks later. All patients received dapson as a lactoperoxidase inhibitor at a dose of 50 mg daily for 8 weeks. The study was conducted during the period from January 2006 to end of October 2006. H 2 O 2 concentration was determined by an enzymatic assay. Determination of exhaled breath condensate for hydrogen peroxide concentration after 8 weeks of dapson usage indicated an increase (1.05 ± 0.36 µM; 95% CI, 0.89-1.21 as compared to that at baseline ( P < 0.0001, 2 weeks ( P < 0.001 and 4 weeks ( P > 0.05. The increase in hydrogen peroxide concentration in exhaled breath condensate after inhibition of lactoperoxidase by dapson advocates a potential role for lactoperoxidase in scavenging of hydrogen peroxide in asthmatic airway.

  11. Hydrogen peroxide and the evolution of oxygenic photosynthesis

    Science.gov (United States)

    Mckay, C. P.; Hartman, H.

    1991-01-01

    Possible pathways for the evolution of oxygenic photosynthesis in the early reducing atmosphere of the earth are discussed. It is suggested that the abiotic production of atmospheric oxidants could have provided a mechanism by which locally oxidizing conditions were sustained within spatially confined habitats thus removing the available reductants and forcing photosynthetic organisms to utilize water (rather than ferrous or sulfide ions) as the electron donor. It is argued that atmospheric H2O2 played the key role in inducing oxygenic photosynthesis, because, as peroxide concentrations local environments increased, primitive organisms would not only be faced with a loss of a reductant, but would be also forced to develop a biochemical apparatus (such as catalase) that would protect them against the products of oxygenic photosynthesis. This scenario allows for the early evolution of oxygenic photosynthesis at the time when global conditions were still anaerobic.

  12. Normal Platelet Integrin Function in Mice Lacking Hydrogen Peroxide-Induced Clone-5 (Hic-5.

    Directory of Open Access Journals (Sweden)

    Michael Popp

    Full Text Available Integrin αIIbβ3 plays a central role in the adhesion and aggregation of platelets and thus is essential for hemostasis and thrombosis. Integrin activation requires the transmission of a signal from the small cytoplasmic tails of the α or β subunit to the large extracellular domains resulting in conformational changes of the extracellular domains to enable ligand binding. Hydrogen peroxide-inducible clone-5 (Hic-5, a member of the paxillin family, serves as a focal adhesion adaptor protein associated with αIIbβ3 at its cytoplasmic tails. Previous studies suggested Hic-5 as a novel regulator of integrin αIIbβ3 activation and platelet aggregation in mice. To assess this in more detail, we generated Hic-5-null mice and analyzed activation and aggregation of their platelets in vitro and in vivo. Surprisingly, lack of Hic-5 had no detectable effect on platelet integrin activation and function in vitro and in vivo under all tested conditions. These results indicate that Hic-5 is dispensable for integrin αIIbβ3 activation and consequently for arterial thrombosis and hemostasis in mice.

  13. A novel non-enzyme hydrogen peroxide sensor based on an electrode modified with carbon nanotube-wired CuO nanoflowers

    International Nuclear Information System (INIS)

    We have prepared a novel sensor for hydrogen peroxide that is based on a glassy carbon electrode modified with a film containing multi-walled carbon nanotubes wired to CuO nanoflowers. The nanoflowers were characterized by X-ray powder diffraction, and the electrode was characterized by cyclic voltammetry (CV) and scanning electron microscopy. The response of the modified electrode towards hydrogen peroxide was investigated by CV and chronoamperometry and showed it to exhibit high electrocatalytic activity, with a linear range from 0. 5 μM to 82 μM and a detection limit of 0. 16 μM. The sensor also displays excellent selectivity and stability. (author)

  14. Hydrogen peroxide detection with high specificity in living cells and inflamed tissues

    OpenAIRE

    Rong, Lei; Zhang, Chi; Lei, Qi; HU, MING-MING; Feng, Jun; Shu, Hong-Bing; Liu, Yi; Zhang, Xian-Zheng

    2016-01-01

    Hydrogen peroxide (H2O2) detection in biological systems is of significant importance, which act as critical second messenger in fundamental biological processes. Here, we report on a chemoselective fluorescent naphthylimide peroxide probe (NPP) for the H2O2 detection in vitro and in vivo. NPP is a phenylboronic acid-caged chromophore that selectively responds to H2O2 through a self-immolate mechanism. NPP exhibited high sensitivity and selectivity to H2O2 with distinctive fluorescence change...

  15. Solvent extraction of tungsten with tri-n-octylamine from hydrogen peroxide solutions

    International Nuclear Information System (INIS)

    Conditions for fast metallic tungsten dissolution in hydrogen peroxide solutions are found and regularities of its extraction by tri-n-octylamine in the form of peroxide compounds and isopolytungstates from hydrochloric, sulfuric acid nitric acid solutions are studied. W and TOA ratio in the formed organic complex is determined by studying extraction isotherms using equilibrium shift, saturation, isomolar series, IR spectrometry methods and this complex'es composition is assumed. Radiochemical circuit of extraction-chromatographic separation of tungsten and rhenium is developed and a method for fast isolation of rhenium-183, 184 radio nuclides from metallic tungsten, irradiated with charged particles is proposed

  16. Suicide inactivation of covalent peroxidase-mimicking DNAzyme with hydrogen peroxide and its protection by a reductant substrate.

    Science.gov (United States)

    Gribas, Anastasia V; Zatsepin, Timofey S; Korolev, Sergey P; Gottikh, Marina B; Sakharov, Ivan Yu

    2016-08-01

    Recently a covalent peroxidase-mimicking DNAzyme (cPMDNAzyme) with the improved catalytic activity was prepared. Here we demonstrate that hydrogen peroxide, the oxidant substrate of cPMDNAzyme is an inactivating agent of this catalyst. Presence of the reductant substrate, 2,2'-azino-bis(3-ethylbenthothiazoline-6-sulfonic acid (ABTS) prevents the inactivation of cPMDNAzyme. The experimental conditions (pH-optimum, concentrations of ABTS and H2O2) for the determination of cPMDNAzyme activity were optimized that allows a construction of the colorimetric cPMDNAzyme-based biosensors and assays with improved sensitivity. PMID:27216675

  17. Amperometric hydrogen peroxide and glucose biosensor based on NiFe2/ordered mesoporous carbon nanocomposites.

    Science.gov (United States)

    Xiang, Dong; Yin, Longwei; Ma, Jingyun; Guo, Enyan; Li, Qun; Li, Zhaoqiang; Liu, Kegao

    2015-01-21

    Nanocomposites of NiFex embedded in ordered mesoporous carbon (OMC) (x = 0, 1, 2) were prepared by a wet impregnation and hydrogen reduction process and were used to construct electrochemical biosensors for the amperometric detection of hydrogen peroxide (H2O2) or glucose. The NiFe2/OMC nanocomposites were demonstrated to have a large surface area, suitable mesoporous channels, many edge-plane-like defective sites, and a good distribution of alloyed nanoparticles. The NiFe2/OMC and Nafion modified glass carbon electrode (GCE) exhibited excellent electrocatalytic activities toward the reduction of H2O2 as well. By utilizing it as a bioplatform, GOx (glucose oxidase) cross-linked with Nafion was immobilized on the surface of the electrode for the construction of an amperometric glucose biosensor. Our results indicated that the amperometric hydrogen peroxide biosensor (NiFe2/OMC + Nafion + GCE) showed good analytical performances in term of a high sensitivity of 4.29 μA mM(-1) cm(-2), wide linearity from 6.2 to 42,710 μM and a low detection limit of 0.24 μM at a signal-to-noise ratio of 3 (S/N = 3). This biosensor exhibited excellent selectivity, high stability and negligible interference for the detection of H2O2. In addition, the immobilized enzyme on NiFe2/OMC + Nafion + GCE, retaining its bioactivity, exhibited a reversible two-proton and two-electron transfer reaction, a fast heterogeneous electron transfer rate and an effective Michaelis-Menten constant (K) (3.18 mM). The GOx + NiFe2/OMC + Nafion + GCE could be used to detect glucose based on the oxidation of glucose catalyzed by GOx and exhibited a wide detection range of 48.6-12,500 μM with a high sensitivity of 6.9 μA mM(-1) cm(-2) and a low detection limit of 2.7 μM (S/N = 3). The enzymic biosensor maintained a high selectivity and stability features, and shows great promise for application in the detection of glucose. PMID:25429370

  18. Efficacy of hydrogen peroxide in controlling mortality associated with saprolegniasis on walleye, white sucker, and paddlefish eggs

    Science.gov (United States)

    Gaikowski, M.P.; Rach, J.J.; Drobish, M.; Hamilton, J.; Harder, T.; Lee, L.A.; Moen, C.; Moore, A.

    2003-01-01

    The efficacy of hydrogen peroxide in controlling saprolegniasis on eggs of walleye Stizostedion vitreum, white sucker Catostomus commersoni, and paddlefish Polyodon spathula was evaluated at four private, state, and federal production hatcheries participating in an Investigational New Animal Drug efficacy study (experiment 1; walleyes) and in a laboratory-based miniature egg jar incubation system (experiment 2; walleyes, white suckers, and paddlefish). Naturally occurring fungal infestations (saprolegniasis) were observed on eggs in both experiments. Confirmatory diagnosis of infested eggs from one hatchery in experiment 1 identified the pathogen as Saprolegnia parasitica. During experiment 1, eggs were treated daily for 15 min with either 0, 500, or 750 mg/L of hydrogen peroxide, and one trial compared a 500-mg/L hydrogen peroxide treatment with a formalin treatment at 1,667 mg/L. Saprolegniasis infestation was observed in control egg jars, whereas treatment with either formalin or hydrogen peroxide virtually eliminated the infestation. Hydrogen peroxide treatments of 500 mg/L either increased egg hatch or were as effective as physical removal of infested eggs in controlling mortality. Although treatment with formalin at 1,667 mg/L significantly increased the percent eye-up of walleye eggs compared with that of those treated with hydrogen peroxide at 500 mg/L, the difference was only 1.9-2.6%. In experiment 2, noneyed eggs were treated for 15 min every other day with 0, 283, 565, or 1,130 mg/L of hydrogen peroxide until the viable eggs hatched. Saprolegniasis infestation engulfed most control eggs, whereas infestation of treated eggs was either reduced or not visible. Hydrogen peroxide significantly increased egg hatch for all three species tested in experiment 2. Although hydrogen peroxide treatments as low as 283 mg/L significantly increased walleye and white sucker hatch, treatments between 500 and 1,000 mg/L are more likely to be effective in production egg

  19. Exogenous low-dose hydrogen peroxide enhances drought tolerance of soybean (Glycine max L.) through inducing antioxidant system.

    Science.gov (United States)

    Guler, Neslihan Saruhan; Pehlivan, Necla

    2016-06-01

    Hydrogen peroxide (H(2)O(2)) functions as a signal molecule in plants under abiotic and biotic stress. In this study, the role of exogenous H(2)O(2) in improving drought tolerance in two soybean cultivars (Glycine max L. Merrill) differing in their tolerance to drought was evaluated. Plants were grown in plastic pots with normal irrigation in a phytotron. Four weeks after radicle emergence, either 1 mM H(2)O(2) or distilled water was sprayed as foliar onto the leaves of each plant, after drought stress was applied. Leaf samples were harvested on the 4(th) and 7(th) days of the drought. Antioxidant-related enzyme activity, such as the superoxide dismutase (SOD), catalase (CAT), ascorbate peroxidase (APX), glutathione reductase (GR), monodehydroascorbate reductase (MDHAR), dehydroascorbate reductase (DHAR), hydrogen peroxide (H(2)O(2)) and malondialdehyde (MDA) content was measured during the drought period. Drought stress decreased leaf water potential, relative water content and photosynthetic pigment content but enhanced lipid peroxidation and endogenous H(2)O(2) concentration. By contrast, exogenous low dose H(2)O(2) improved water status, pigment content and lipid peroxidation under drought stress. Endogenous H(2)O(2) concentration was reduced by exogenous H(2)O(2) as compared to drought treatment alone. H(2)O(2) pre-treatment induced all the antioxidant enzyme activities, to a greater extent than the control leaves, during drought. H(2)O(2) pretreatment further enhanced the activities of antioxidant enzymes in the tolerant cultivar compared to the sensitive cultivar. Results suggested that low dose H(2)O(2) pre-treatment alleviated water loss and H(2)O(2) content and increased drought stress tolerance by inducing the antioxidant system. PMID:27165528

  20. Exogenous low-dose hydrogen peroxide enhances drought tolerance of soybean (Glycine max L.) through inducing antioxidant system.

    Science.gov (United States)

    Guler, Neslihan Saruhan; Pehlivan, Necla

    2016-06-01

    Hydrogen peroxide (H(2)O(2)) functions as a signal molecule in plants under abiotic and biotic stress. In this study, the role of exogenous H(2)O(2) in improving drought tolerance in two soybean cultivars (Glycine max L. Merrill) differing in their tolerance to drought was evaluated. Plants were grown in plastic pots with normal irrigation in a phytotron. Four weeks after radicle emergence, either 1 mM H(2)O(2) or distilled water was sprayed as foliar onto the leaves of each plant, after drought stress was applied. Leaf samples were harvested on the 4(th) and 7(th) days of the drought. Antioxidant-related enzyme activity, such as the superoxide dismutase (SOD), catalase (CAT), ascorbate peroxidase (APX), glutathione reductase (GR), monodehydroascorbate reductase (MDHAR), dehydroascorbate reductase (DHAR), hydrogen peroxide (H(2)O(2)) and malondialdehyde (MDA) content was measured during the drought period. Drought stress decreased leaf water potential, relative water content and photosynthetic pigment content but enhanced lipid peroxidation and endogenous H(2)O(2) concentration. By contrast, exogenous low dose H(2)O(2) improved water status, pigment content and lipid peroxidation under drought stress. Endogenous H(2)O(2) concentration was reduced by exogenous H(2)O(2) as compared to drought treatment alone. H(2)O(2) pre-treatment induced all the antioxidant enzyme activities, to a greater extent than the control leaves, during drought. H(2)O(2) pretreatment further enhanced the activities of antioxidant enzymes in the tolerant cultivar compared to the sensitive cultivar. Results suggested that low dose H(2)O(2) pre-treatment alleviated water loss and H(2)O(2) content and increased drought stress tolerance by inducing the antioxidant system.

  1. Partial oxidation of n-hexadecane through decomposition of hydrogen peroxide in supercritical water

    KAUST Repository

    Alshammari, Y.M.

    2015-01-01

    © 2014 The Institution of Chemical Engineers. This work reports the experimental analysis of partial oxidation of n-hexadecane under supercritical water conditions. A novel reactor flow system was developed which allows for total decomposition of hydrogen peroxide in a separate reactor followed partial oxidation of n-hexadecane in a gasification reactor instead of having both reactions in one reactor. The kinetics of hydrothermal decomposition of hydrogen peroxide was studied in order to confirm its full conversion into water and oxygen under the desired partial oxidation conditions, and the kinetic data were found in a good agreement with previously reported literature. The gas yield and gasification efficiency were investigated under different operating parameters. Furthermore, the profile of C-C/C=C ratio was studied which showed the favourable conditions for maximising yields of n-alkanes via hydrogenation of their corresponding 1-alkenes. Enhanced hydrogenation of 1-alkenes was observed at higher O/C ratios and higher residence times, shown by the increase in the C-C/C=C ratio to more than unity, while increasing the temperature has shown much less effect on the C-C/C=C ratio at the current experimental conditions. In addition, GC-MS analysis of liquid samples revealed the formation of heavy oxygenated compounds which may suggest a new addition reaction to account for their formation under the current experimental conditions. Results show new promising routes for hydrogen production with in situ hydrogenation of heavy hydrocarbons in a supercritical water reactor.

  2. Major effect of hydrogen peroxide on bacterioplankton metabolism in the Northeast Atlantic.

    Directory of Open Access Journals (Sweden)

    Federico Baltar

    Full Text Available Reactive oxygen species such as hydrogen peroxide have the potential to alter metabolic rates of marine prokaryotes, ultimately impacting the cycling and bioavailability of nutrients and carbon. We studied the influence of H2O2 on prokaryotic heterotrophic production (PHP and extracellular enzymatic activities (i.e., β-glucosidase [BGase], leucine aminopeptidase [LAPase] and alkaline phosphatase [APase] in the subtropical Atlantic. With increasing concentrations of H2O2 in the range of 100-1000 nM, LAPase, APase and BGase were reduced by up to 11, 23 and 62%, respectively, in the different water layers. Incubation experiments with subsurface waters revealed a strong inhibition of all measured enzymatic activities upon H2O2 amendments in the range of 10-500 nM after 24 h. H2O2 additions also reduced prokaryotic heterotrophic production by 36-100% compared to the rapid increases in production rates occurring in the unamended controls. Our results indicate that oxidative stress caused by H2O2 affects prokaryotic growth and hydrolysis of specific components of the organic matter pool. Thus, we suggest that oxidative stress may have important consequences on marine carbon and energy fluxes.

  3. Styrene epoxidation with hydrogen peroxide over calcium oxide catalysts prepared from various precursors

    Institute of Scientific and Technical Information of China (English)

    Qingming Gu; Dan Han; Lei Shi; Qi Sun

    2012-01-01

    A series of CaO samples were prepared by calcination of commercially available and synthesis of calcium salt precursors such as calcium acetate,carbonate,hydroxide and oxalate etc.CaO samples were found to be effective for the epoxidation of styrene using hydrogen peroxide as an oxidant in the presence of acetonitrile.To determine the influence of the physicochemical properties and surface basicity on the catalytic activity,the prepared CaO samples were characterized using thermogravimetry (TG),X-ray diffraction (XRD),scanning electron microscopy (SEM),N2-adsorption and temperature-programmed desorption of CO2 (CO2-TPD).The results indicate that the amounts of very strong basic sites and high basicity strength on CaO sample are key factors for its excellent catalytic performance.In contrast,the surface area,porosity and the surface structure of CaO sample have a relatively minor effect on the catalytic activity.CaO sample,obtained by the decomposition of Ca(OH)2,prepared by precipitating calcium nitrate with sodium hydroxide in ethylene glycol solution,exhibits the highest amount of very strong basic sites and stronger strength of basic sites,and therefore it catalyses the epoxidation of styrene with the highest rate among the tested CaO samples.Under the selected reaction conditions,the selectivity of 97.5% to styrene oxide at a conversion in excess of 99% could be obtained.

  4. Growth, photosynthesis, and antioxidant responses of Vigna unguiculata L. treated with hydrogen peroxide

    Directory of Open Access Journals (Sweden)

    Syed Aiman Hasan

    2016-12-01

    Full Text Available Cowpea (Vigna unguiculata L. is an important legume well grown in semiarid and arid environment. Hydrogen peroxide solutions (0.1, 0.5, 1.0, and 1.5 mM have been used to optimize growth and photosynthetic performance of cowpea plant at two growth stages [30 and 45 DAS (days of sowing]. Foliar application of H2O2 at 0.5 > 1.0 mM solution at 29 DAS optimally promoted the photosynthetic attributes [leaf chlorophyll content, net photosynthetic rate (PN, water use efficiency, and maximum quantum yield of PSII (Fv/Fm] and growth performance [root and shoot length; fresh and dry weight] of plants where the responses were more significant at the later growth stage. It was favored by activity of enzymes as carbonic anhydrase [CA; E.C. 4.2.1.1] and nitrate reductase [NR, E.C. 1.6.6.1] and those of antioxidant enzymes viz. peroxidase [POX; EC 1.11.1.7], catalase [CAT; EC 1.11.1.6], and superoxide dismutase [SOD; EC 1.15.1.1] and leaf proline content. Strengthened root system and antioxidant activity, particularly leaf proline level appeared to be the key factor for efficient photosynthesis and growth responses.

  5. Nitrogen-doped graphene-silver nanodendrites for the non-enzymatic detection of hydrogen peroxide

    International Nuclear Information System (INIS)

    Highlights: • N-graphene/Ag nanodendrities by electrophoretic and electrochemical deposition. • Support of N-graphene shows efficient electrocatalytic activity toward H2O2 reduction. • The fabricated non-enzymatic H2O2 electrochemical sensor improved in the presence of Ag. - Abstract: An organic-metal hybrid film based on nitrogen-doped graphene-silver nanodendrites (Ag-NG) was fabricated on an indium tin oxide (ITO) electrode using a simple electrophoretic and electrochemical sequential deposition approach. The microwave-assisted method was utilized for the synthesis of nitrogen-doped graphene. This method involves a three-step process consisting of graphite oxidation, exfoliation, and finally chemical reduction with the use of hydrazine as the reducing agent, which leads to the simultaneous reduction of graphene oxide and production of nitrogen-doped graphene. The morphology and structure of the as-fabricated electrode were determined by X-ray diffraction, field emission electron microscopy and transmission electron microscopy. The as-prepared Ag-NG-modified ITO electrode exhibited superior electrocatalytic activity toward hydrogen peroxide (H2O2) reduction, with a wide linear detection range of 100 μM to 80 mM (r = 0.9989) and a detection limit of 0.26 μM with a signal-to-noise ratio of 3. Furthermore, the fabricated non-enzymatic H2O2 electrochemical sensor exhibited excellent stability and reproducibility

  6. Redox Response of Reduced Graphene Oxide-Modified Glassy Carbon Electrodes to Hydrogen Peroxide and Hydrazine

    Directory of Open Access Journals (Sweden)

    Jun-ichi Anzai

    2013-05-01

    Full Text Available The surface of a glassy carbon (GC electrode was modified with reduced graphene oxide (rGO to evaluate the electrochemical response of the modified GC electrodes to hydrogen peroxide (H2O2 and hydrazine. The electrode potential of the GC electrode was repeatedly scanned from −1.5 to 0.6 V in an aqueous dispersion of graphene oxide (GO to deposit rGO on the surface of the GC electrode. The surface morphology of the modified GC electrode was characterized by scanning electron microscopy (SEM and atomic force microscopy (AFM. SEM and AFM observations revealed that aggregated rGO was deposited on the GC electrode, forming a rather rough surface. The rGO-modified electrodes exhibited significantly higher responses in redox reactions of H2O2 as compared with the response of an unmodified GC electrode. In addition, the electrocatalytic activity of the rGO-modified electrode to hydrazine oxidation was also higher than that of the unmodified GC electrode. The response of the rGO-modified electrode was rationalized based on the higher catalytic activity of rGO to the redox reactions of H2O2 and hydrazine. The results suggest that rGO-modified electrodes are useful for constructing electrochemical sensors.

  7. Bioconversion of paper mill sludge to bioethanol in the presence of accelerants or hydrogen peroxide pretreatment.

    Science.gov (United States)

    Gurram, Raghu Nandan; Al-Shannag, Mohammad; Lecher, Nicholas Joshua; Duncan, Shona M; Singsaas, Eric Lawrence; Alkasrawi, Malek

    2015-09-01

    In this study we investigated the technical feasibility of convert paper mill sludge into fuel ethanol. This involved the removal of mineral fillers by using either chemical pretreatment or mechanical fractionation to determine their effects on cellulose hydrolysis and fermentation to ethanol. In addition, we studied the effect of cationic polyelectrolyte (as accelerant) addition and hydrogen peroxide pretreatment on enzymatic hydrolysis and fermentation. We present results showing that removing the fillers content (ash and calcium carbonate) from the paper mill sludge increases the enzymatic hydrolysis performance dramatically with higher cellulose conversion at faster rates. The addition of accelerant and hydrogen peroxide pretreatment further improved the hydrolysis yields by 16% and 25% (g glucose / g cellulose), respectively with the de-ashed sludge. The fermentation process of produced sugars achieved up to 95% of the maximum theoretical ethanol yield and higher ethanol productivities within 9h of fermentation. PMID:26086086

  8. Spinach Root-Tissue Based Amperometric Biosensor for the Determination of Hydrogen Peroxide

    Energy Technology Data Exchange (ETDEWEB)

    Lee, B.G. [Chosun University, Kwangju (Korea); Yoon, K.J. [Chongju University, Chongju (Korea); Kwon, H.S. [Chungbuk National University, Chongju (Korea)

    2000-06-01

    The response characteristics of the bioelectrode developed by the co-immobilization of spinach root tissue and ferrocene in a carbon paste matrix for the amperometric determination of hydrogen peroxide were evaluated. In the range of electrode potential examined (-0.3{approx}0.0 V vs. Ag/AgCl), the response time was relatively short (t{sub 95%}=11.8 sec) and it responded in the wide range of pH. Also, its detection limit was 2.25*10{sup -6}M (S/N=3) and a relative standard deviation of the measurements which were repeated 15 times using 1.0*10{sup -3}M hydrogen peroxide was 1.87%. The bioelectrode sensitivity decreased to 40% of the original value in 19 days of continuous use. (author). 35 refs., 8 figs.

  9. Enamel susceptibility to red wine staining after 35% hydrogen peroxide bleaching

    Directory of Open Access Journals (Sweden)

    Sandrine Bittencourt Berger

    2008-06-01

    Full Text Available Concern has been expressed regarding the staining of enamel surface by different beverages after bleaching. This study investigated the influence of 35% hydrogen peroxide bleaching agents on enamel surface stained with wine after whitening treatments. Flat and polished bovine enamel surfaces were submitted to two commercially available 35% hydrogen peroxide bleaching agents or kept in 100% humidity, as a control group (n = 10. Specimens of all groups were immersed in red wine for 48 h at 37°C, immediately, 24 h or 1 week after treatments. All specimens were ground into powder and prepared for the spectrophotometric analysis. Data were subjected to two-way analysis of variance and Fisher's PLSD test at 5% significance level. The amount of wine pigments uptake by enamel submitted to bleaching treatments was statistically higher than that of control group, independently of the evaluation time. Results suggested that wine staining susceptibility was increased by bleaching treatments.

  10. Hydrogen peroxide biosensor based on electrodeposition of zinc oxide nanoflowers onto carbon nanotubes film electrode

    Institute of Scientific and Technical Information of China (English)

    Hui Ping Bai; Xu Xiao Lu; Guang Ming Yang; Yun Hui Yang

    2008-01-01

    A new amperometric biosensor for hydrogen peroxide was developed based on adsorption of horseradish peroxidase at the glassy carbon electrode modified with zinc oxide nanoflowers produced by electrodeposition onto multi-walled carbon nanotubes (MWNTs) firm. The morphology of the MWNTs/nano-ZnO electrode has been investigated by scanning electron microscopy (SEM), and the electrochemical performance of the electrode has also been studied by amperometric method. The resulting electrode offered an excellent detection for hydrogen peroxide at -0.11 V with a linear response range of 9.9 × 10(-7) to 2.9 × 10(-3) mol/L with a correlation coefficient of 0.991, and response time <5 s. The biosensor displays rapid response and expanded linear response range, and excellent stability.

  11. The Life Story of Hydrogen Peroxide III: Chirality and Physical Effects at the Dawn of Life

    Science.gov (United States)

    Ball, Rowena; Brindley, John

    2016-03-01

    It is a remarkable observed fact that all life on Earth is homochiral, its biology using exclusively the D-enantiomer of ribose, the sugar moiety of the ribonucleic acids, and the L-enantiomers of the chiral amino acids. Motivated by concurrent work that elaborates further the role of hydrogen peroxide in providing an oscillatory drive for the RNA world (Ball & Brindley 2015a, J. R. Soc. Interface 12, 20150366, and Ball & Brindley 2015b, this journal, in press), we reappraise the structure and physical properties of this small molecule within this context. Hydrogen peroxide is the smallest, simplest molecule to exist as a pair of non-superimposable mirror images, or enantiomers, a fact which leads us to develop the hypothesis that its enantiospecific interactions with ribonucleic acids led to enantioselective outcomes. We propose a mechanism by which these chiral interactions may have led to amplification of D-ribonucleic acids and extinction of L-ribonucleic acids.

  12. Kinetics study on photochemical oxidation of polyacrylamide by ozone combined with hydrogen peroxide and ultraviolet radiation

    Institute of Scientific and Technical Information of China (English)

    REN Guang-meng; SUN De-zhi; CHUNG Jong Shik

    2006-01-01

    An investigation on the process of ozone combined with hydrogen peroxide and ultraviolet radiation has been carried out in order to establish the kinetics for photochemical oxidation of polyacrylamide (PAM) in aqueous solution. Effects of operating parameters, including initial PAM concentration, dosages of ozone and hydrogen peroxide, UV radiation and pH value on the photochemical oxidation of PAM, have been studied. There was an increase in photochemical oxidation rate of PAM with increasing of dosages of O3, H2O2 and ultraviolet radiation. Upon increasing of the initial PAM concentration, the photochemical oxidation rate of PAM decreased. Slight effect of pH value on the photochemical oxidation rate of PAM was observed in the experiments. The kinetics equation for the photochemical oxidation of PAM by the system has been established.

  13. Synthesis of Kappa-carrageenan oligomers via synergistic action of gamma radiation and hydrogen peroxide

    International Nuclear Information System (INIS)

    In this study, the synthesis of k-carrageenan oligometers with the simultaneous action of gamma radiation and hydrogen peroxide was carried out. Effects on molecular weight and structure of k-carrageenan were assessed using GPC, UV-VIS and FT-IR. Radiation degradation yield (G(s)) and reaction rate constants (k) based on Mn values were also determined. The results showed that k-carrageenan oligomers with Mw of less than 10 kDa can be prepared easily at low doses (2.5-5 kGy) in the presence of low concentrations of hydrogen peroxide (0.25-0.5%). The G(s)) and k values increased significantly with the presence of H2O2. Structural changes in k-carrageenan treated by the degradation agents were accompanied by appearance of UV peak at 260 nm and characteristic FT-IR band at 1728 cm-1. (Author)

  14. Electrochemical behavior of hydrogen peroxide sensor based on new methylene blue as mediator

    Institute of Scientific and Technical Information of China (English)

    MA Jie; WU Hai; ZHU Yaqi

    2007-01-01

    A novel amperometric hydrogen peroxide sensor was proposed by co-immobilizing new methylene blue (NMB) and Horseradish peroxidase (HRP) on glassy carbon electrode through covalent binding.The electrochemical behavior of the sensor was studied extensively in 0.1 mol/L phosphate buffering solution (pH = 7.0).The experiments showed NMB could effectively transfer electrons between hydrogen peroxide and glassy carbon electrode.The electron transfer coefficient and apparent reaction rate constant were determined to be 0.861 and 1.27 s-1.The kinetic characteristics and responses of sensor on HzO2 were investigated.The Michaelis constant is 8.27 mol/L and the linear dependence of current on H2O2 is in the range of 2.5-100 μmol/L.At the same time,the effects of solution pH,buffer capacity,and temperature on the sensor were examined.

  15. The Life Story of Hydrogen Peroxide III: Chirality and Physical Effects at the Dawn of Life.

    Science.gov (United States)

    Ball, Rowena; Brindley, John

    2016-03-01

    It is a remarkable observed fact that all life on Earth is homochiral, its biology using exclusively the D-enantiomer of ribose, the sugar moiety of the ribonucleic acids, and the L-enantiomers of the chiral amino acids. Motivated by concurrent work that elaborates further the role of hydrogen peroxide in providing an oscillatory drive for the RNA world (Ball & Brindley 2015a, J. R. Soc. Interface 12, 20150366, and Ball & Brindley 2015b, this journal, in press), we reappraise the structure and physical properties of this small molecule within this context. Hydrogen peroxide is the smallest, simplest molecule to exist as a pair of non-superimposable mirror images, or enantiomers, a fact which leads us to develop the hypothesis that its enantiospecific interactions with ribonucleic acids led to enantioselective outcomes. We propose a mechanism by which these chiral interactions may have led to amplification of D-ribonucleic acids and extinction of L-ribonucleic acids.

  16. Formation of water-soluble soybean polysaccharides from spent flakes by hydrogen peroxide treatment

    DEFF Research Database (Denmark)

    Pierce, Brian; Wichmann, Jesper; Tran, Tam H.;

    2016-01-01

    In this paper we propose a novel chemical process for the generation of water-soluble polysaccharides from soy spent flake, a by-product of the soy food industry. This process entails treatment of spent flake with hydrogen peroxide at an elevated temperature, resulting in the release of more than...... 70% of the original insoluble material as high molar mass soluble polysaccharides. A design of experiment was used to quantify the effects of pH, reaction time, and hydrogen peroxide concentration on the reaction yield, average molar mass, and free monosaccharides generated. The resulting product...... is low in protein, fat, and minerals and contains predominantly water-soluble polysaccharides of high molar mass, including arabinan, type I arabinogalactan, homogalacturonan, xyloglucan, rhamnogalacturonan, and (glucurono)arabinoxylan. This treatment provides a straightforward approach for generation...

  17. Nitric oxide-based protein modification: formation and site-specificity of protein S-nitrosylation: Could protein S-nitrosylation be the unifying oxidative modification to explain the cellular signaling activity of superoxide and hydrogen peroxide?

    Science.gov (United States)

    Clement, Marie-Veronique

    2014-10-01

    Accumulating evidence indicates that reactive oxygen species (ROS) and reactive nitrogen species (RNS) function as signaling molecules in physiological settings by acting as second messengers in response to external stimuli such as growth factors, cytokines and hormones. The nature of the ROS involved in cell signaling as well as the underlying mechanisms by which ROS modify protein function to influence cellular processes have been unfolding over the past decade. ROS and RNS influence various cellular processes by altering the function of critical proteins via reversible oxidation of "reactive cysteine" residues. Protein S-nitrosylation is a mechanism of nitric oxide-based signaling, however, while the presence of NO is sufficient and may be a prerequisite for the formation of cysteine-SNO, we reasoned that if protein-SNO formation is a critical cystein modification for redox driven signal transduction, an increase in intracellular ROS such as H2O2 and O2(-), shown to be independently involved in cell signaling, might both promote the formation of protein-SNO. In this respect, the present study shows that an increase in protein-SNO was detected not only upon an increase in the intracellular level of nitric oxide (NO), but also following exposure to low concentration of exogenous hydrogen peroxide (H2O2) or upon inhibition of the Cu/Zn superoxide dismutase that results in increased intracellular O2(-). PMID:26461291

  18. Maize seed coatings and seedling sprayings with chitosan and hydrogen peroxide: their influence on some phenological and biochemical behaviors

    OpenAIRE

    Lizárraga-Paulín, Eva-Guadalupe; Miranda-Castro, Susana-Patricia; Moreno-Martínez, Ernesto; Lara-Sagahón, Alma-Virginia; Torres-Pacheco, Irineo

    2013-01-01

    Objective: To evaluate the effect of chitosan (CH) and hydrogen peroxide (H2O2) seed coatings and seedling sprinklings on two different maize varieties by measuring their phenology, the H2O2 presence, the catalase (CAT) activity, and the protein quantity. Methods: Seven groups of ten seeds for each maize variety were treated with CH (2% (20 g/L) and 0.2% (2 g/L)) or H2O2 (8 mmol/L) by coating, sprinkling, or both. Germination and seedling growth were measured. One month after germination, the...

  19. Effects of Rutaecarpine on Hydrogen Peroxide-Induced Apoptosis in Murine Hepa-1c1c7 Cells

    OpenAIRE

    Lee, Sung-Jin; Ahn, Hyunjin; Nam, Kung-Woo; Kim, Kyeong Ho; Mar, Woongchon

    2012-01-01

    The aim of this study was to investigate the inhibitory effects of rutaecarpine on DNA strand breaks and apoptosis induced by hydrogen peroxide (H2O2) in murine Hepa-1c1c7 cells. Oxidative DNA damage was estimated by nuclear condensation assessment, fluorescence-activated cell sorting analysis, and Comet assay. Rutaecarpine inhibited cell death induced by 500 μM H2O2, as assessed by 4',6-diamidino-2-phenylindole (DAPI) staining. Treatment with rutaecarpine reduced the number of DNA strand bre...

  20. Experimental evaluation of hydrogen peroxide catalysts for monopropellant attitude control thrusters

    OpenAIRE

    Palmer, Matthew James

    2014-01-01

    Currently the space community relies on propellants such as hydrazine and its derivatives in propulsion systems aboard satellites and spacecraft. However their highly toxic and carcinogenic nature results in significant costs in handling, storage and transport compared to less toxic propellants. It is due to this benefit that there is a renewed interest in ‘green’ or less toxic propellants. One such green propellant is hydrogen peroxide. This liquid propellant must be catalytically decomposed...

  1. Towards understanding a distinct hydrogen peroxide electrocatalytic enhancement using surfactant-based coatings on silver

    OpenAIRE

    Goodison, Alan; Gonzalez-Macia, Laura; Killard, Anthony J.; Morrin, Aoife

    2013-01-01

    The detection of hydrogen peroxide has been shown to be very important in recent years due to its relevant role in many industrial applications as well as biological reactions. We are interested in it as a quantitative marker for oxidase-based biosensor applications where it is produced when substrate (e.g., glucose, cholesterol) is catalysed by its respective oxidase enzyme. Previously, a commercial silver flake-based screen-printing ink (PF-410, Acheson®), when coated with surfactant and...

  2. CIDEX, SAVLON AND HYDROGEN PEROXIDE: WHICH OF THEM IS MORE EFFECTIVE IN DISINFECTION OF VENTILATOR TUBES

    Directory of Open Access Journals (Sweden)

    H SOLTANI NEZHAD

    2001-12-01

    Full Text Available Introduction: Nasocomial infections threat any hospitalized patient, specially in intensive care unit. Incidence of these infections has been reported from 1.9 to more than 25 percent. The most common nasocomial infection in intensive care units (ICU is pneumonia caused by endotraheal intubation and mechanical ventilation. The best procedure for pneumonia prevention in patients under mechanical ventilation is utilization of suitable and proper techniques for equipment sterilization: The goal of this study is determination and comparison of disinfectant materials (cidex, savlon and hydrogen peroxide about their effects on incidence and type of mechanical ventilators breathing tubes contamination in intensive care unit. Methods: This is an experimental trial which was done on three groups of mechanical ventilator breathing tubes. Each group contained 20 samples. These three groups of breathing tubes were disinfected with cidex, savlon and hydrogen peroxide. Samples were obtained from tubes for microbial culture berore and after disinfection. Samples were cultured on blood agar. The results of microbial culturing were compared between three groups. Results: There was no significant difference between three groups of breathing tubes about microbial types and number of colony counted before disinfection. There was no significant difference between cultured colony numbers in three groups before and after disinfection. Cidex, savlon and hydrogen peroxide could decrease incidence of contamination to 100, 98.09 and 100 percent, respectively. Discussion: All of tested chemical materials have the same results in disinfection. Hydrogen peroxide has less adverse effect on human and environment than cidex. It is less expensive than cidex. So, we recommend to use this material for disifection of mechanical ventilator berthing tubes.

  3. New considerations on hydrogen peroxide and related substances as food additives in view of carcinogenicity.

    Science.gov (United States)

    Ito, R

    1982-01-01

    The use of hydrogen peroxide as a labile and safe food preservative in fish cake and boiled noodles has recently been restricted by the Japanese government, since hyperplasia has been found in the duodenum of mice after long-term peroral study. The action of compounds with resembling mode of action, potassium bromate as an improving agent in bread, and sodium chlorate as a weed killer are discussed in this paper in view of developmental and environmental pharmacology. PMID:7078983

  4. Two-photon fluorescence imaging of intracellular hydrogen peroxide with chemoselective fluorescent probes

    OpenAIRE

    Guo, Hengchang; Aleyasin, Hossein; Howard, Scott S.; Dickinson, Bryan C; Lin, Vivian S.; Haskew-Layton, Renee E.; Xu, Chris; Chen, Yu; Ratan, Rajiv R.

    2013-01-01

    Abstract. We present the application of two-photon fluorescence (TPF) imaging to monitor intracellular hydrogen peroxide (H2O2) production in brain cells. For selective imaging of H2O2 over other reactive oxygen species, we employed small-molecule fluorescent probes that utilize a chemoselective boronate deprotection mechanism. Peroxyfluor-6 acetoxymethyl ester detects global cellular H2O2 and mitochondria peroxy yellow 1 detects mitochondrial H2O2. Two-photon absorption cross sections for th...

  5. Two-photon fluorescence imaging of intracellular hydrogen peroxide with chemoselective fluorescent probes

    OpenAIRE

    Guo, Hengchang; Aleyasin, Hossein; Howard, Scott S.; Dickinson, Bryan C; Lin, Vivian S.; Haskew-Layton, Renee E.; Xu, Chris; Chen, Yu; Ratan, Rajiv R.

    2013-01-01

    Abstract. We present the application of two-photon fluorescence (TPF) imaging to monitor intracellular hydrogen peroxide ( H 2 O 2 ) production in brain cells. For selective imaging of H 2 O 2 over other reactive oxygen species, we employed small-molecule fluorescent probes that utilize a chemoselective boronate deprotection mechanism. Peroxyfluor-6 acetoxymethyl ester detects global cellular H 2 O 2 and mitochondria peroxy yellow 1 detects mitochondrial H 2 O 2 . Two-photon absorption cross ...

  6. Patterns of hydrogen peroxide among lakes of the Mackenzie Delta and potential effects on bacterial production

    OpenAIRE

    Febria, Catherine Maria

    2005-01-01

    Lakes in the Mackenzie Delta have complex patterns of dissolved organic carbon (DOC) ranging from low levels of coloured DOC in lakes frequently flooded with riverwater to high levels of non-coloured DOC in infrequently flooded lakes. Hydrogen peroxide (H202) levels measured in 40 lakes at three times, ranging from summer solstice to late summer were highest around the solstice and in lakes of intermediate flood-frequency. Diurnal dynamics of H202, tracked for 40 hours during 24-hour sunlight...

  7. Oxidative stress markers in neurological diseases and disorders: electrochemical detection of hydrogen peroxide and nitric oxide

    OpenAIRE

    O'Riordan, Saidhbhe

    2013-01-01

    The aim of this thesis is to further demonstrate the electrochemical detection of nitric oxide (NO) and hydrogen peroxide (H2O2) in-vitro, to advance the previously demonstrated detection of brain NO and to demonstrate the novel in-vivo detection of H2O2 using a paired catalase-based biosensor. We have recently successfully demonstrated the real-time detection of brain NO using a previously characterised Nafion®-modified platinum (Pt) electrochemical sensor. Additionally, th...

  8. Photocatalytic degradation of Phenol Red using complexes of some transition metals and hydrogen peroxide

    Directory of Open Access Journals (Sweden)

    SAVITRI LODHA

    2008-06-01

    Full Text Available The photocatalytic degradation of Phenol Red was investigated using thiocyanate complexes of iron, copper, cobalt and hydrogen peroxide. The rate of photocatalytic degradation of the dye was followed spectrophotometrically. The effect of the variation of different parameters, such as pH, concentration of the complexes and dye, amount of H2O2 and light intensity on the rate of photocatalytic degradation was also studied. A tentative mechanism for the photocatalytic degradation of Phenol Red is proposed.

  9. Mesenchymal stem cells restore frataxin expression and increase hydrogen peroxide scavenging enzymes in Friedreich ataxia fibroblasts.

    Directory of Open Access Journals (Sweden)

    Kevin Kemp

    Full Text Available Dramatic advances in recent decades in understanding the genetics of Friedreich ataxia (FRDA--a GAA triplet expansion causing greatly reduced expression of the mitochondrial protein frataxin--have thus far yielded no therapeutic dividend, since there remain no effective treatments that prevent or even slow the inevitable progressive disability in affected individuals. Clinical interventions that restore frataxin expression are attractive therapeutic approaches, as, in theory, it may be possible to re-establish normal function in frataxin deficient cells if frataxin levels are increased above a specific threshold. With this in mind several drugs and cytokines have been tested for their ability to increase frataxin levels. Cell transplantation strategies may provide an alternative approach to this therapeutic aim, and may also offer more widespread cellular protective roles in FRDA. Here we show a direct link between frataxin expression in fibroblasts derived from FRDA patients with both decreased expression of hydrogen peroxide scavenging enzymes and increased sensitivity to hydrogen peroxide-mediated toxicity. We demonstrate that normal human mesenchymal stem cells (MSCs induce both an increase in frataxin gene and protein expression in FRDA fibroblasts via secretion of soluble factors. Finally, we show that exposure to factors produced by human MSCs increases resistance to hydrogen peroxide-mediated toxicity in FRDA fibroblasts through, at least in part, restoring the expression of the hydrogen peroxide scavenging enzymes catalase and glutathione peroxidase 1. These findings suggest, for the first time, that stem cells may increase frataxin levels in FRDA and transplantation of MSCs may offer an effective treatment for these patients.

  10. A Model of Redox Kinetics Implicates the Thiol Proteome in Cellular Hydrogen Peroxide Responses

    OpenAIRE

    Adimora, Nnenna J.; Jones, Dean P; Melissa L Kemp

    2010-01-01

    Hydrogen peroxide is appreciated as a cellular signaling molecule with second-messenger properties, yet the mechanisms by which the cell protects against intracellular H2O2 accumulation are not fully understood. We introduce a network model of H2O2 clearance that includes the pseudo-enzymatic oxidative turnover of protein thiols, the enzymatic actions of catalase, glutathione peroxidase, peroxiredoxin, and glutaredoxin, and the redox reactions of thioredoxin and glutathione. Simulations repro...

  11. Spatial, Temporal, and Quantitative Manipulation of Intracellular Hydrogen Peroxide in Cultured Cells

    OpenAIRE

    Alim, Ishraq; Haskew-Layton, Renee E.; Aleyasin, Hossein; Guo, Hengchang; Ratan, Rajiv R.

    2014-01-01

    Hydrogen peroxide (H2O2) is produced endogenously in a number of cellular compartments, including the mitochondria, the endoplasmic reticulum, peroxisomes, and at the plasma membrane, and can play divergent roles as a second messenger or a pathological toxin. It is assumed that the tuned production of H2O2 within neuronal and non-neuronal cells regulates a discreet balance between survival and death. However, a major challenge in understanding the physiological versus pathological role of H2O...

  12. Oxidation of chlorophenols catalyzed by Coprinus cinereus peroxidase with in situ production of hydrogen peroxide.

    Science.gov (United States)

    Pezzotti, Fabio; Okrasa, Krzysztof; Therisod, Michel

    2004-01-01

    Degradation of 2,6-dichlorophenol (2,6-DCP) was accomplished by oxidation catalyzed by Coprinus cinereus peroxidase. Immobilization of the enzyme in a polyacrylamide matrix enhanced DCP oxidation. Hydrogen peroxide, peroxidase's natural substrate, was produced enzymatically in situ to avoid peroxidase inactivation by its too high concentration. In the case of larger scale utilization, the method would also avoid direct handling of this hazardous reagent.

  13. Hydrogen Peroxide Contributes to the Epithelial Cell Death Induced by the Oral Mitis Group of Streptococci

    OpenAIRE

    Okahashi, Nobuo; Sumitomo, Tomoko; Nakata, Masanobu; Sakurai, Atsuo; Kuwata, Hirotaka; Kawabata, Shigetada

    2014-01-01

    Members of the mitis group of streptococci are normal inhabitants of the commensal flora of the oral cavity and upper respiratory tract of humans. Some mitis group species, such as Streptococcus oralis and Streptococcus sanguinis, are primary colonizers of the human oral cavity. Recently, we found that hydrogen peroxide (H2O2) produced by S. oralis is cytotoxic to human macrophages, suggesting that streptococcus-derived H2O2 may act as a cytotoxin. Since epithelial cells provide a physical ba...

  14. The Role of Hydrogen Peroxide in Environmental Adaptation of Oral Microbial Communities

    OpenAIRE

    Lin Zhu; Jens Kreth

    2012-01-01

    Oral streptococci are able to produce growth-inhibiting amounts of hydrogen peroxide (H2O2) as byproduct of aerobic metabolism. Several recent studies showed that the produced H2O2 is not a simple byproduct of metabolism but functions in several aspects of oral bacterial biofilm ecology. First, the release of DNA from cells is closely associated to the production of H2O2 in Streptococcus sanguinis and Streptococcus gordonii. Extracellular DNA is crucial for biofilm development and stabilizati...

  15. Molecular Imaging Approaches to Understanding the Roles of Hydrogen Peroxide Biology in Stress and Development

    OpenAIRE

    Dickinson, Bryan Craig

    2010-01-01

    The production of hydrogen peroxide (H2O2) in biological systems is associated with a variety of pathologies including neurodegenerative diseases, cancer, and the general process of aging. However, a growing body of evidence suggests that the reactivity of this particular reactive oxygen species (ROS) is also harnessed for physiological processes. Molecular imaging using fluorescence microscopy offers a valuable approach for deciphering the multifaceted roles of H2O2 in biological processes. ...

  16. Role for the oxyS Gene in Regulation of Intracellular Hydrogen Peroxide in Escherichia coli

    OpenAIRE

    González-Flecha, Beatriz; Demple, Bruce

    1999-01-01

    Intracellular hydrogen peroxide is regulated in Escherichia coli by OxyR in response to the metabolic production of H2O2. Here, we show that the untranslated oxyS RNA controlled by OxyR has a role in this regulation. The oxyS transcript appears to affect the metabolic output of H2O2 rather than the removal of H2O2 by catalases-hydroperoxidases.

  17. Photosensitized decomposition of hydrogen peroxide by the uranyl ion, production of hydroperoxide radicals

    International Nuclear Information System (INIS)

    The photosensitized decomposition of hydrogen peroxide by the uranyl ion in sulfuric acid media has been demonstrated and the kinetics of oxygen evolution have been measured as a function of the initial concentrations. The HO2 radical stabilized by complexation with UO22+ is an intermediate in this decomposition. This reaction can be employed in the photoassisted oxidation of diverse organic molecules using UO22+ as the sensitizer

  18. Distinctive Oxidative Stress Responses to Hydrogen Peroxide in Sulfate Reducing Bacteria Desulfovibrio vulgaris Hildenborough

    OpenAIRE

    Zhou, Aifen

    2010-01-01

    Response of Desulfovibrio vulgaris Hildenborough to hydrogen peroxide (H2O2, 1 mM) was investigated with transcriptomic, proteomic and genetic approaches. Microarray data demonstrated that gene expression was extensively affected by H2O2 with the response peaking at 120 min after H2O2 treatment. Genes affected include those involved with energy production, sulfate reduction, ribosomal structure and translation, H2O2 scavenging, posttranslational modification and DNA repair as evidenced by gen...

  19. Hydrogen peroxide and hydroxyl radical formation by methylene blue in the presence of ascorbic acid

    International Nuclear Information System (INIS)

    Using ESR we have demonstrated the formation of the ascorbate free radical from sodium ascorbate, methylene blue and light. In oxygen uptake experiments we have observed the production of hydrogen peroxide while spin trapping experiments have revealed the iron catalyzed production of the hydroxyl free radical in this system. The presence of this highly reactive radical suggests that it could be the radical that initiates free radical damage in this photodynamic system. (orig.)

  20. Polymer Supported Heterogenous Catalysts for Direct Synthesis of Hydrogen Peroxide in Absence of Selectivity Enhancers

    OpenAIRE

    Sterchele, Stefano

    2013-01-01

    The research program developed during the Ph.D. School is focused on the study of metal catalysts supported on cross-linked functional polymers (CFPs) for the direct synthesis of hydrogen peroxide. In the last twenty years this compound has become a commodity with a constant increasing demand because of its strong oxidant properties and the formation of water as the reduction byproduct. In particular, H2O2 is widely employed as environmentally-friendly bleaching and cleaning agent. The...

  1. Sonochemical and hydrodynamic cavitation reactors for laccase/hydrogen peroxide cotton bleaching.

    Science.gov (United States)

    Gonçalves, Idalina; Martins, Madalena; Loureiro, Ana; Gomes, Andreia; Cavaco-Paulo, Artur; Silva, Carla

    2014-03-01

    The main goal of this work is to develop a novel and environmental-friendly technology for cotton bleaching with reduced processing costs. This work exploits a combined laccase-hydrogen peroxide process assisted by ultrasound. For this purpose, specific reactors were studied, namely ultrasonic power generator type K8 (850 kHz) and ultrasonic bath equipment Ultrasonic cleaner USC600TH (45 kHz). The optimal operating conditions for bleaching were chosen considering the highest levels of hydroxyl radical production and the lowest energy input. The capacity to produce hydroxyl radicals by hydrodynamic cavitation was also assessed in two homogenizers, EmulsiFlex®-C3 and APV-2000. Laccase nanoemulsions were produced by high pressure homogenization using BSA (bovine serum albumin) as emulsifier. The bleaching efficiency of these formulations was tested and the results showed higher whiteness values when compared to free laccase. The combination of laccase-hydrogen peroxide process with ultrasound energy produced higher whiteness levels than those obtained by conventional methods. The amount of hydrogen peroxide was reduced 50% as well as the energy consumption in terms of temperature (reduction of 40 °C) and operating time (reduction of 90 min). PMID:24035719

  2. Comparison of chemiluminescence methods for analysis of hydrogen peroxide and hydroxyl radicals

    Energy Technology Data Exchange (ETDEWEB)

    Pehrman, R.; Amme, M. (European Commission, Joint Research Centre, Institute for Transuranium Elements, Karlsruhe, (Germany)); Cachoir, C. (SCK.CEN, Waste and Disposal Unit., Mol (Belgium))

    2010-03-15

    Full text: Disposal of spent nuclear fuel in underground repositories is being considered in many countries and for this purpose understanding of behaviour of radiolysis products is required. To study the effects of alpha radiolysis products of water on oxidation and dissolution of actinides, a method to analyse those products is needed. Chemiluminescence is generally considered a simple, sensitive and reasonably selective method to detect reactive oxygen species on low concentrations. Concentrations of interest for both hydrogen peroxide and hydroxyl radicals are 10-6 to 10-9 M. The aim of this study is to compare various chemiluminescence methods for detecting hydrogen peroxide and hydroxyl radicals. Four methods to analyse hydrogen peroxide were chosen based on the estimated suitability for radiolysis experiments. Two of these use luminol, catalyzed by either mu-peroxidase or hemin, one uses 10-methyl-9-(p-formylphenyl) acridinium carboxylate trifluoromethanesulfonate and one potassium periodate. All methods were tested as batch systems in basic conditions. For hydroxyl radical detection luminophores tested were 3-hydroxyphthalic hydrazide (product of phthalic hydrazide and hydroxyl radical) and rutin. Both methods were tested as batch systems. The results are compared and the applicability of the methods for near-field dissolution studies is discussed. (author)

  3. Toxicity of abiotic stressors to Fusarium species: differences in hydrogen peroxide and fungicide tolerance.

    Science.gov (United States)

    Nagygyörgy, Emese D; Kovács, Barbara; Leiter, Eva; Miskei, Márton; Pócsi, István; Hornok, László; Adám, Attila L

    2014-06-01

    Stress sensitivity of three related phytopathogenic Fusarium species (Fusarium graminearum, Fusarium oxysporum and Fusarium verticillioides) to different oxidative, osmotic, cell wall, membrane, fungicide stressors and an antifungal protein (PAF) were studied in vitro. The most prominent and significant differences were found in oxidative stress tolerance: all the three F. graminearum strains showed much higher sensitivity to hydrogen peroxide and, to a lesser extent, to menadione than the other two species. High sensitivity of F. verticillioides strains was also detectable to an azole drug, Ketoconazole. Surprisingly, no or limited differences were observed in response to other oxidative, osmotic and cell wall stressors. These results indicate that fungal oxidative stress response and especially the response to hydrogen peroxide (this compound is involved in a wide range of plant-fungus interactions) might be modified on niche-specific manner in these phylogenetically related Fusarium species depending on their pathogenic strategy. Supporting the increased hydrogen peroxide sensitivity of F. graminearum, genome-wide analysis of stress signal transduction pathways revealed the absence one CatC-type catalase gene in F. graminearum in comparison to the other two species.

  4. Hydrogen peroxide production by ion irradiation of thin water ice films

    International Nuclear Information System (INIS)

    In this paper we present the results of new experiments on ion irradiation of water ice performed on thin films to study the synthesis of the hydrogen peroxide molecule and discuss the possibility of detecting it in icy mantles on interstellar grains. The used experimental technique has been in situ infrared spectroscopy. We have irradiated thin films (i.e. the ice thickness was smaller than the penetration depth of the used ion) with three different ions, namely 200 keV of H+ and He+ and 400 keV of Ar++. The experiments were carried out at temperatures of 16 and 77 K. We have found that hydrogen peroxide is produced by all of the different ions at both temperatures. The detection of such a molecule has been possible from the study of its infrared feature centered at about 2850 cm-1 (3.5 μm). The obtained results also show that the produced H2O2/H2O(%) ratio is greater for the heaviest ion (∼6% for the case of Ar++) and that H+ is the ion that produces the smallest quantity (∼1%). These upper limits in the production of hydrogen peroxide constrain the quantity of H2O2 that can be formed after bombardment by cosmic particles on icy mantles of grains in the interstellar medium. (authors)

  5. Numerical and experimental analysis of heat transfer in injector plate of hydrogen peroxide hybrid rocket motor

    Science.gov (United States)

    Cai, Guobiao; Li, Chengen; Tian, Hui

    2016-11-01

    This paper is aimed to analyze heat transfer in injector plate of hydrogen peroxide hybrid rocket motor by two-dimensional axisymmetric numerical simulations and full-scale firing tests. Long-time working, which is an advantage of hybrid rocket motor over conventional solid rocket motor, puts forward new challenges for thermal protection. Thermal environments of full-scale hybrid rocket motors designed for long-time firing tests are studied through steady-state coupled numerical simulations of flow field and heat transfer in chamber head. The motor adopts 98% hydrogen peroxide (98HP) oxidizer and hydroxyl-terminated poly-butadiene (HTPB) based fuel as the propellants. Simulation results reveal that flowing liquid 98HP in head oxidizer chamber could cool the injector plate of the motor. The cooling of 98HP is similar to the regenerative cooling in liquid rocket engines. However, the temperature of the 98HP in periphery portion of the head oxidizer chamber is higher than its boiling point. In order to prevent the liquid 98HP from unexpected decomposition, a thermal protection method for chamber head utilizing silica-phenolics annular insulating board is proposed. The simulation results show that the annular insulating board could effectively decrease the temperature of the 98HP in head oxidizer chamber. Besides, the thermal protection method for long-time working hydrogen peroxide hybrid rocket motor is verified through full-scale firing tests. The ablation of the insulating board in oxygen-rich environment is also analyzed.

  6. Effects of 15% carbamide peroxide and 40% hydrogen peroxide on the microhardness and color change of composite resins.

    Directory of Open Access Journals (Sweden)

    Sedighe Sadat Hashemi Kamangar

    2014-04-01

    Full Text Available The aim of this study was to determine the effects of 40% hydrogen peroxide and 15% carbamide peroxide on microhardness and color change of a silorane-based composite resin in comparison with two methacrylate-based composites.Fifty-four disc-shaped specimens (A3 shade were fabricated of Filtek P90 (P90, Filtek Z350XT Enamel (Z350 and Filtek Z250 (Z250 (3MESPE (n=18. The samples of each composite were randomly divided into three subgroups of 6. The control subgroups were immersed in distilled water; the test groups were exposed to Opalescence Boost (OB once; and Opalescence PF (OP (Ultradent for two weeks. Vickers microhardness testing and a spectrophotometric analysis of the color of samples were performed before and after each intervention.The baseline microhardness of P90 was significantly lower than that of the other two composites (P=0.001, but no difference was found between Z250 and Z350 in this respect (P=0.293. Bleaching treatments significantly decreased the microhardness of Z250 and Z350 (P 0.05. No significant difference was detected between the two types of bleaching (P>0.05. After bleaching with OB, ΔE value was measured to be 3.12(1.97, 3.31(1.84 and 3.7(2.11 for P90, Z250 and Z350, respectively. These values were 5.98(2.42, 4.66(2.85 and 4.90(2.78 after bleaching with OP with no significant difference.Bleaching decreased the microhardness of methacrylate-based but not silorane-based composites. Although no significant differences were found in ΔE of composites, ΔE of all groups did not remain in the clinically acceptable range after bleaching except for P90 after bleaching with 40% H2O2 (ΔE < 3.3.

  7. Lactoperoxidase-catalyzed oxidation of thiocyanate by hydrogen peroxide: sup 15 N nuclear magnetic resonance and optical spectral studies

    Energy Technology Data Exchange (ETDEWEB)

    Modi, S.; Deodhar, S.S.; Behere, D.V.; Mitra, S. (Tata Institute of Fundamental Research, Bombay (India))

    1991-01-01

    To establish the agent(s) responsible for the activity of the lactoperoxidase (LPO)/SCN{sup {minus}}/H{sub 2}O{sub 2} system, the oxidation of thiocyanate with hydrogen peroxide, catalyzed by lactoperoxidase, has been studied by {sup 15}N NMR and optical spectroscopy at different concentrations of thiocyanate and hydrogen peroxide and at different pHs. The formation of hypothiocyanite ion (OSCN{sup {minus}}) as one of the oxidation products correlated well with activity of the LPO/SCN{sup {minus}}/H{sub 2}O{sub 2} system and was maximum when the concentrations of the H{sub 2}O{sub 2} and SCN{sup {minus}} were nearly the same and the pH was <6.0. At (H{sub 2}O{sub 2})/(SCN{sup {minus}}) = 1, OSCN{sup {minus}} decomposed very slowly back to thiocyanate. When the ratio (H{sub 2}O{sub 2})/(SCN{sup {minus}}) was above 2, formation of CN{sup {minus}} was observed, which was confirmed by {sup 15}N NMR and also by changes in the optical spectrum of LPO. The oxidation of thiocyanate by H{sub 2}O{sub 2} in the presence of LPO does not take place at pH >8.0. Since thiocyanate does not bind to LPO above this pH, the binding of thiocyanate to LPO is considered to be prerequisite for the oxidation of thiocyanate. Maximum inhibition of oxygen uptake by Streptococcus cremoris 972 bacteria was observed when hydrogen peroxide and thiocyanate were present in equimolar amounts and the pH was below 6.0.

  8. Pneumococcal hydrogen peroxide-induced stress signaling regulates inflammatory genes.

    Science.gov (United States)

    Loose, Maria; Hudel, Martina; Zimmer, Klaus-Peter; Garcia, Ernesto; Hammerschmidt, Sven; Lucas, Rudolf; Chakraborty, Trinad; Pillich, Helena

    2015-01-15

    Microbial infections can induce aberrant responses in cellular stress pathways, leading to translational attenuation, metabolic restriction, and activation of oxidative stress, with detrimental effects on cell survival. Here we show that infection of human airway epithelial cells with Streptococcus pneumoniae leads to induction of endoplasmic reticulum (ER) and oxidative stress, activation of mitogen-associated protein kinase (MAPK) signaling pathways, and regulation of their respective target genes. We identify pneumococcal H2O2 as the causative agent for these responses, as both catalase-treated and pyruvate oxidase-deficient bacteria lacked these activities. Pneumococcal H2O2 induced nuclear NF-κB translocation and transcription of proinflammatory cytokines. Inhibition of translational arrest and ER stress by salubrinal or of MAPK signaling pathways attenuate cytokine transcription. These results provide strong evidence for the notion that inhibition of translation is an important host pathway in monitoring harmful pathogen-associated activities, thereby enabling differentiation between pathogenic and nonpathogenic bacteria. PMID:25183769

  9. Dynamics of hydrogen peroxide in a coral reef: Sources and sinks

    Science.gov (United States)

    Shaked, Yeala; Armoza-Zvuloni, Rachel

    2013-12-01

    dynamics of hydrogen peroxide (H2O2) was studied in the fringing coral reef off the coast of Eilat, Red Sea. Diurnal changes in H2O2 concentrations in the reef lagoon were typical of photochemically produced species. During the daytime H2O2 accumulated in the lagoon at low tide and exceeded open water concentrations by 100-250 nM. Elevated H2O2 decay kinetics (termed hereafter antioxidant activity) were also recorded in the lagoon at low tide. The observed antioxidant activities were high enough to moderate H2O2 accumulation in the lagoon. In pursuit of the antioxidant source, the ability of corals to release antioxidant activity to their surrounding water was examined in both natural and laboratory settings. Water collected in situ from surfaces of individual corals and next to a coral knoll contained high antioxidant activity. Incubation experiments revealed that many Red Sea corals release antioxidant activity to their external milieu. Besides serving a potential antioxidant source to the reef system, the antioxidant activity detected on coral surfaces enabled corals to lower H2O2 concentrations in their vicinity. The ability of corals to offset exogenous H2O2 was validated in incubations with Stylophora pistillata in the absence of mixing. Conversely, corals subjected to mixing in a beaker were found to release H2O2, implying that corals may act as both a sink and a source for H2O2 in the reef. This newly described ability of corals to change H2O2 dynamics by releasing both H2O2 and antioxidants may bare important implications for coral physiology and interactions with the environment.

  10. Human Umbilical Cord Wharton's Jelly Stem Cell Conditioned Medium Induces Tumoricidal Effects on Lymphoma Cells Through Hydrogen Peroxide Mediation.

    Science.gov (United States)

    Lin, Hao Daniel; Fong, Chui-Yee; Biswas, Arijit; Choolani, Mahesh; Bongso, Ariff

    2016-09-01

    Several groups have reported that human umbilical cord Wharton's jelly stem cells (hWJSCs) possess unique tumoricidal properties against many cancers. However, the exact mechanisms as to how hWJSCs inhibit tumor growth are not known. Recent evidence suggests that exposure of cancer cells to high hydrogen peroxide (H2 O2 ) levels from H2 O2 -releasing drugs causes their death. We therefore explored whether the tumoricidal effect of hWJSCs on lymphoma cells was mediated via H2 O2 . We first exposed lymphoma cells to six different molecular weight cut-off (MWCO) concentrates of hWJSC-conditioned medium (hWJSC-CM) (3, 5, 10, 30, 50, 100 kDa) for 48 h. Since, the 3 kDa-MWCO concentrate showed the greatest cell inhibition we then investigated whether the tumoricidal effect of the specific 3 kDa-MWCO concentrate on two different lymphoma cell lines (Ramos and Toledo) was mediated via accumulation of H2 O2 . We used a battery of assays (MTT, propidium iodide, mitochondria membrane potential, apoptosis, cell cycle, oxidative stress enzymes, hydrogen peroxide, mitochondrial superoxide, hydroxyl radical, peroxynitrile anion, and lipid peroxidation) to test this mechanism. The hWJSC-CM-3 kDa MWCO concentrate significantly decreased cell viability and mitochondrial membrane potential and increased cell death and apoptosis in both lymphoma cell lines. There were significant increases in superoxide dismutase with concomitant decreases in glutathione peroxidase, catalase, and thioredoxin peroxidase activities. H2 O2 levels, mitochondrial superoxide, hydroxyl radical, peroxynitrile anion, and lipid peroxidation were also significantly increased in both lymphoma cell lines. The results suggested that the hWJSC-CM-3 kDa MWCO concentrate regulates cellular H2 O2 leading to a tumoricidal effect and may thus be a promising anti-lymphoma agent. J. Cell. Biochem. 117: 2045-2055, 2016. © 2016 Wiley Periodicals, Inc. PMID:27392313

  11. Antifouling effect of hydrogen peroxide release from enzymatic marine coatings: Exposure testing under equatorial and Mediterranean conditions

    DEFF Research Database (Denmark)

    Olsen, S.M.; Kristensen, J.B.; Laursen, B.S.;

    2010-01-01

    Hydrogen peroxide (H2O2) may be considered an environmentally friendly antifouling alternative to common biocides such as Cu2O and various organic compounds. In this work, the efficiency of antifouling coatings releasing hydrogen peroxide via enzyme-mediated conversion of starch, under Mediterran......Hydrogen peroxide (H2O2) may be considered an environmentally friendly antifouling alternative to common biocides such as Cu2O and various organic compounds. In this work, the efficiency of antifouling coatings releasing hydrogen peroxide via enzyme-mediated conversion of starch, under...... formulated have been characterised in terms of common coating characteristics and immersed on rafts in seawater outside Singapore and Spain to monitor antifouling efficiency. The results have been compared to results previously reported from temperate waters in the North Sea outside The Netherlands. Using...

  12. Efficacy of a Low Dose of Hydrogen Peroxide (Peroxy Ag+) for Continuous Treatment of Dental Unit Water Lines: Challenge Test with Legionella pneumophila Serogroup 1 in a Simulated Dental Unit Waterline

    OpenAIRE

    Savina Ditommaso; Monica Giacomuzzi; Elisa Ricciardi; Zotti, Carla M

    2016-01-01

    This study was designed to examine the in vitro bactericidal activity of hydrogen peroxide against Legionella. We tested hydrogen peroxide (Peroxy Ag+) at 600 ppm to evaluate Legionella survival in a simulated dental treatment water system equipped with Water Hygienization Equipment (W.H.E.) device that was artificially contaminated. When Legionella pneumophila serogroup (sg) 1 was exposed to Peroxy Ag+ for 60 min we obtained a two decimal log reduction. High antimicrobial efficacy was obtain...

  13. A Hydrogen Peroxide Biosensor Combined HRP Doped Polypyrrole with Ferrocene Modified Sol-gel Derived Composite Carbon Electrode

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    A novel amperometric biosensor for the detection of hydrogen peroxide is described.The biosensor was constructed by electrodepositing HRP/PPy membrane on the surface of ferrocenecarboxylic acid mediated sol-gel derived composite carbon electrode. The biosensor gives response to hydrogen peroxide in a few seconds with detection limit of 5×l0-7 mol · L-1(based on signal: noise=3). Linear range is up to 0.2 mmol · L-1.

  14. Introduction of Hydrogen Peroxide as an Oxidant in Flow Injection Analysis: Speciation of Cr(III) and Cr(VI)

    DEFF Research Database (Denmark)

    Andersen, Jens Enevold Thaulov

    1998-01-01

    Hydrogen peroxide was used as an oxidant in Flow Injection Analysis (FIA). The formation of gaseous components during the analysis was suppressed by maintaining a concentration lower than 0.15% of hydrogen peroxide in 0.1 M NaOH. By this method Cr(III) was oxidised on-line to Cr(VI) which...... at concentrations above 6 mg/L which is suitable for on-line monitoring of e.g. waste waters....

  15. Oxidation of 2,4-dinitrophenol by hydrogen peroxide in the presence of basic oxygen furnace slag.

    Science.gov (United States)

    Li, Y S; You, Y H; Lien, E T

    1999-11-01

    A treatment process was developed when basic oxygen furnace slag (BOF slag) and hydrogen peroxide were used to oxidize 2, 4-dinitrophenol from an aqueous solution. BOF slag, final waste slurry from steel making plants, contains about 12.5% by weight of ferrous oxide. In an acid solution, BOF slag can be dissociated to produce ferrous ions and react with hydrogen peroxide to produce hydroxyl radicals and oxidize 2,4-dinitrophenol. The results of the research demonstrated that the process had a significant capacity for oxidation of 2,4-dinitrophenol from the aqueous phase. Various factors critical to the oxidation of 2,4-dinitrophenol were studied, including hydrogen peroxide concentration, concentration of BOF slag, initial concentration of 2,4-dinitrophenol, and pH value of solution. Experimental results proved that 100 mg/L 2, 4-dinitrophenol and its oxidation intermediate could be totally decomposed within 60 min by 10 g/L BOF slag, 0.18 g/L hydrogen peroxide and pH 2.8 +/- 0.2. The optimum hydrogen peroxide concentration for degradation of 100 mg/L of 2,4-dinitrophenol is between 0.09 g/L and 0.18 g/L as 10 g/L BOF slag in the solution of pH 2.8 +/- 0.2. A hydrogen peroxide concentration higher than 0.18 g/L is disadvantageous to the oxidation process. The oxidation efficiency increased with the increase of BOF slag concentration at 0.18 g/L hydrogen peroxide dose. The best pH value of the solution is in the vicinity of 2.8. An oxidation reaction mechanism was proposed for predicting the concentration changes of 2, 4-dinitrophenol, ferrous ion, and hydrogen peroxide.http://link. springer-ny.com/link/service/journals/00244/bibs/37n4p427.++ +html

  16. Involvement of intracellular free Ca2+ in enhanced release of herpes simplex virus by hydrogen peroxide

    Directory of Open Access Journals (Sweden)

    Ogawa Yuzo

    2006-08-01

    Full Text Available Abstract Background It was reported that elevation of the intracellular concentration of free Ca2+ ([Ca2+]i by a calcium ionophore increased the release of herpes simplex virus type 1 (HSV-1. Freely diffusible hydrogen peroxide (H2O2 is implied to alter Ca2+ homeostasis, which further enhances abnormal cellular activity, causing changes in signal transduction, and cellular dysfunction. Whether H2O2 could affect [Ca2+]i in HSV-1-infected cells had not been investigated. Results H2O2 treatment increased the amount of cell-free virus and decreased the proportion of viable cells. After the treatment, an elevation in [Ca2+]i was observed and the increase in [Ca2+]i was suppressed when intracellular and cytosolic Ca2+ were buffered by Ca2+ chelators. In the presence of Ca2+ chelators, H2O2-mediated increases of cell-free virus and cell death were also diminished. Electron microscopic analysis revealed enlarged cell junctions and a focal disintegration of the plasma membrane in H2O2-treated cells. Conclusion These results indicate that H2O2 can elevate [Ca2+]i and induces non-apoptotic cell death with membrane lesions, which is responsible for the increased release of HSV-1 from epithelial cells.

  17. A new enzymatic immobilization carrier based on graphene capsule for hydrogen peroxide biosensors

    International Nuclear Information System (INIS)

    Enzymatic loss and inactivation are two main problems which can affect the performance of the biosensor. In order to resolve these two problems, a new kind of enzymatic biosensor for the amperometric detection of hydrogen peroxide (H2O2) was developed using biomimetic graphene capsules (GRCAPS). Horseradish peroxidase was initially encapsulated in GRCAPS using porous CaCO3 as sacrificial templates to mimic the existence form of bio-enzymes in the organisms, and then GRCAPS and graphene-poly(sodium 4-styrenesulfonate) were alternatively assembled onto the substrate of indium tin oxide for constructing multilayer films of the biosensor. Transmittance electron microscopy and field-emission scanning electron microscopy analyses proved that the GRCAPS and multilayer films were prepared. Electrochemical experiment results indicated that easy, direct electrochemistry and good catalytic activity toward H2O2 oxidation can be achieved with this biosensor. The resulting biosensor presented a wide linear range of 0.01–12 mmol l−1, a low detection limit of 3.3 μmol l−1 (S/N = 3), excellent anti-interference ability, and long-term stability as well

  18. Photoinduced green synthesis of silver nanoparticles with highly effective antibacterial and hydrogen peroxide sensing properties.

    Science.gov (United States)

    Kumar, Vijay; Gundampati, Ravi Kumar; Singh, Devendra K; Bano, Daraksha; Jagannadham, Medicherla V; Hasan, Syed Hadi

    2016-09-01

    In this study, an eco-friendly and sustainable green route was employed for the synthesis of stable silver nanoparticles (AgNPs) using aqueous leaf extract of Euphorbia hirta (AEE) as both reducing as well as a stabilizing agent. The synthesis of AgNPs was confirmed by UV-visible spectroscopy which produced a prominent SPR band at λmax 425nm after 25min of sunlight exposure. The AgNPs thus synthesized were optimized using one factor at a time approach, and these optimized conditions were 25min of sunlight exposure time, 5.0% (v/v) of AEE inoculum dose and 3.0mM of AgNO3 concentration. The Field Emission Scanning Electron Microscopy (FE-SEM) and High Resolution Transmission Electron Microscopy (HRTEM) analysis confirmed the presence of spherical AgNPs with average size 15.5nm. The crystallinity was determined by X-ray Diffractometer (XRD) and Selected Area Electron Diffraction (SAED) pattern. Chemical and elemental compositions were determined by Fourier Transformed Infrared Spectroscopy (FTIR) and Energy Dispersive X-ray Spectroscopy (EDX) respectively. The Atomic Force Microscopy (AFM) images with average roughness 1.15nm represented the lateral and 3D topological characteristic of AgNPs. The AgNPs thus synthesized showed effective antibacterial activity against gram negative and gram positive bacteria as well as hydrogen peroxide sensing property with a minimum detection limit of 10(-7)M. PMID:27424098

  19. Protective Effects of Costunolide against Hydrogen Peroxide-Induced Injury in PC12 Cells.

    Science.gov (United States)

    Cheong, Chong-Un; Yeh, Ching-Sheng; Hsieh, Yi-Wen; Lee, Ying-Ray; Lin, Mei-Ying; Chen, Chung-Yi; Lee, Chien-Hsing

    2016-01-01

    Oxidative stress-mediated cellular injury has been considered as a major cause of neurodegenerative diseases including Alzheimer's and Parkinson's diseases. The scavenging of reactive oxygen species (ROS) mediated by antioxidants may be a potential strategy for retarding the diseases' progression. Costunolide (CS) is a well-known sesquiterpene lactone, used as a popular herbal remedy, which possesses anti-inflammatory and antioxidant activity. This study aimed to investigate the protective role of CS against the cytotoxicity induced by hydrogen peroxide (H₂O₂) and to elucidate potential protective mechanisms in PC12 cells. The results showed that the treatment of PC12 cells with CS prior to H₂O₂ exposure effectively increased the cell viability. Furthermore, it decreased the intracellular ROS, stabilized the mitochondria membrane potential (MMP), and reduced apoptosis-related protein such as caspase 3. In addition, CS treatment attenuated the cell injury by H₂O₂ through the inhibition of phosphorylation of p38 and the extracellular signal-regulated kinase (ERK). These results demonstrated that CS is promising as a potential therapeutic candidate for neurodegenerative diseases resulting from oxidative damage and further research on this topic should be encouraged. PMID:27409597

  20. Therapeutic potential of targeting hydrogen peroxide metabolism in the treatment of brain ischaemia.

    Science.gov (United States)

    Armogida, Marta; Nisticò, Robert; Mercuri, Nicola Biagio

    2012-06-01

    For many years after its discovery, hydrogen peroxide (H₂O₂) was viewed as a toxic molecule to human tissues; however, in light of recent findings, it is being recognized as an ubiquitous endogenous molecule of life as its biological role has been better elucidated. Indeed, increasing evidence suggests that H₂O₂ may act as a second messenger with a pro-survival role in several physiological processes. In addition, our group has recently demonstrated neuroprotective effects of H₂O₂ on in vitro and in vivo ischaemic models through a catalase (CAT) enzyme-mediated mechanism. Therefore, the present review summarizes experimental data supporting a neuroprotective potential of H₂O₂ in ischaemic stroke that has been principally achieved by means of pharmacological and genetic strategies that modify either the activity or the expression of the superoxide dismutase (SOD), glutathione peroxidase (GPx) and CAT enzymes, which are key regulators of H₂O₂ metabolism. It also critically discusses a translational impact concerning the role played by H₂O₂ in ischaemic stroke. Based on these data, we hope that further research will be done in order to better understand the mechanisms underlying H₂O₂ functions and to promote successful H₂O₂ signalling based therapy in ischaemic stroke.

  1. Protective Effects of Costunolide against Hydrogen Peroxide-Induced Injury in PC12 Cells

    Directory of Open Access Journals (Sweden)

    Chong-Un Cheong

    2016-07-01

    Full Text Available Oxidative stress-mediated cellular injury has been considered as a major cause of neurodegenerative diseases including Alzheimer’s and Parkinson’s diseases. The scavenging of reactive oxygen species (ROS mediated by antioxidants may be a potential strategy for retarding the diseases’ progression. Costunolide (CS is a well-known sesquiterpene lactone, used as a popular herbal remedy, which possesses anti-inflammatory and antioxidant activity. This study aimed to investigate the protective role of CS against the cytotoxicity induced by hydrogen peroxide (H2O2 and to elucidate potential protective mechanisms in PC12 cells. The results showed that the treatment of PC12 cells with CS prior to H2O2 exposure effectively increased the cell viability. Furthermore, it decreased the intracellular ROS, stabilized the mitochondria membrane potential (MMP, and reduced apoptosis-related protein such as caspase 3. In addition, CS treatment attenuated the cell injury by H2O2 through the inhibition of phosphorylation of p38 and the extracellular signal-regulated kinase (ERK. These results demonstrated that CS is promising as a potential therapeutic candidate for neurodegenerative diseases resulting from oxidative damage and further research on this topic should be encouraged.

  2. Response of Cytokines and Hydrogen Peroxide to Sporothrix schenckii Exoantigen in Systemic Experimental Infection.

    Science.gov (United States)

    Maia, Danielle Cardoso Geraldo; Gonçalves, Amanda Costa; Ferreira, Lucas Souza; Manente, Francine Alessandra; Portuondo, Deivys Leandro; Vellosa, José Carlos Rebuglio; Polesi, Marisa Campos; Batista-Duharte, Alexander; Carlos, Iracilda Zeppone

    2016-04-01

    The response of hydrogen peroxide (H2O2) and cytokines during an experimental sporotrichosis in male Swiss mice was assessed over a period of 10 weeks by monitoring macrophage activation challenged with exoantigen (ExoAg) from the fungus Sporothrix schenckii. The studied endpoints were: H2O2 production, fungal burden at spleen, apoptosis in peritoneal macrophages, and IL-1β, IL-6, IL-2, IL-10 production. During the two first weeks of infection was observed low burden of yeast in spleen and high response of H2O2, IL-2, and IL-1β. The weeks of highest fungal burden (fourth-sixth) coincided with major apoptosis in peritoneal macrophages, normal production of IL-6 and lower production of H2O2, IL-2, and IL-1β, suggesting a role for these three last in the early control of infection. On the other hand, IL-1β (but not IL-6) was recovered since the sixth week, suggesting a possible role in the late phase of infection, contributing to the fungal clearance in conjunction with the specific mechanisms. The IL-10 was elevated until the sixth, principally in the second week. These results evidences that ExoAg is involved in the host immune modulation, influencing the S. Schenckii virulence, and its role is related with the time of the infection in the model used.

  3. Amperometric Non-Enzymatic Hydrogen Peroxide Sensor Based on Aligned Zinc Oxide Nanorods

    Science.gov (United States)

    Al-Hardan, Naif H.; Abdul Hamid, Muhammad Azmi; Shamsudin, Roslinda; Othman, Norinsan Kamil; Kar Keng, Lim

    2016-01-01

    Zinc oxide (ZnO) nanorods (NRs) have been synthesized via the hydrothermal process. The NRs were grown over a conductive glass substrate. A non-enzymatic electrochemical sensor for hydrogen peroxide (H2O2), based on the prepared ZnO NRs, was examined through the use of current-voltage measurements. The measured currents, as a function of H2O2 concentrations ranging from 10 μM to 700 μM, revealed two distinct behaviours and good performance, with a lower detection limit (LOD) of 42 μM for the low range of H2O2 concentrations (first region), and a LOD of 143.5 μM for the higher range of H2O2 concentrations (second region). The prepared ZnO NRs show excellent electrocatalytic activity. This enables a measurable and stable output current. The results were correlated with the oxidation process of the H2O2 and revealed a good performance for the ZnO NR non-enzymatic H2O2 sensor. PMID:27367693

  4. All-Weather Hydrogen Peroxide-Based Decontamination of CBRN Contaminants

    Energy Technology Data Exchange (ETDEWEB)

    Wagner, George W. [U.S. Army Edgewood Chemical Biological Center (ECBC), Aberdeen Proving Ground, MD (United States); Procell, Lawrence R. [U.S. Army Edgewood Chemical Biological Center (ECBC), Aberdeen Proving Ground, MD (United States); Sorrick, David C. [U.S. Army Edgewood Chemical Biological Center (ECBC), Aberdeen Proving Ground, MD (United States); Lawson, Glenn E. [Naval Surface Warfare Center (NSWC), Dahlgren, VA (United States); Wells, Claire M. [Naval Surface Warfare Center (NSWC), Dahlgren, VA (United States); Reynolds, Charles M. [U.S. Army Cold Regions Research and Engineering Lab. (CRREL), Hanover, NH (United States); Ringelberg, D. B. [U.S. Army Cold Regions Research and Engineering Lab. (CRREL), Hanover, NH (United States); Foley, Karen L. [U.S. Army Cold Regions Research and Engineering Lab. (CRREL), Hanover, NH (United States); Lumetta, Gregg J. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Blanchard, David L. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States)

    2010-03-11

    A hydrogen peroxide-based decontaminant, Decon Green, is efficacious for the decontamination of chemical agents VX (S-2-(diisopropylamino)ethyl O-ethyl methylphosphonothioate), GD (Soman, pinacolyl methylphosphonofluoridate), and HD (mustard, bis(2-chloroethyl) sulfide); the biological agent anthrax (Bacillus anthracis); and radiological isotopes Cs-137 and Co-60; thus demonstrating the ability of this decontamination approach to ameliorate the aftermath of all three types of weapons of mass destruction (WMD). Reaction mechanisms afforded for the chemical agents are discussed as are rationales for the enhanced removal efficacy of recalcitrant 60Co on certain surfaces. Decontaminants of this nature can be deployed, and are effective, at very low temperatures (-32 °C), as shown for studies done with VX and HD simulants, without the need for external heat sources. Finally, the efficacy of a lower-logistics, dry decontaminant powder concentrate (utilizing the solid active-oxygen compounds peracetyl borate and Peroxydone) which can be reconstituted with water in the field prior to use, is presented.

  5. Fabrication of a novel electrochemical sensor for determination of hydrogen peroxide in different fruit juice samples

    Directory of Open Access Journals (Sweden)

    Navid Nasirizadeh

    2016-01-01

    Full Text Available A new hydrogen peroxide (H2O2 sensor is fabricated based on a multiwalled carbon nanotube-modified glassy carbon electrode (MWCNT-GCE and reactive blue 19 (RB. The charge transfer coefficient, α, and the charge transfer rate constant, ks, of RB adsorbed on MWCNT-GCE were calculated and found to be 0.44 ± 0.01 Hz and 1.9 ± 0.05 Hz, respectively. The catalysis of the electroreduction of H2O2 by RB-MWCNT-GCE is described. The RB-MWCNT-GCE shows a dramatic increase in the peak current and a decrease in the overvoltage of H2O2 electroreduction in comparison with that seen at an RB modified GCE, MWCNT modified GCE, and activated GCE. The kinetic parameters such as α and the heterogeneous rate constant, k', for the reduction of H2O2 at RB-MWCNT-GCE surface were determined using cyclic voltammetry. The detection limit of 0.27μM and three linear calibration ranges were obtained for H2O2 determination at the RB-MWCNT-GCE surface using an amperometry method. In addition, using the newly developed sensor, H2O2 was determined in real samples with satisfactory results.

  6. Removal of Polyvinyl Alcohol Using Photoelectrochemical Oxidation Processes Based on Hydrogen Peroxide Electrogeneration

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    Kai-Yu Huang

    2013-01-01

    Full Text Available This study investigates the removal efficiency of PVA from aqueous solutions using UV irradiation in combination with the production of electrogenerated hydrogen peroxide (H2O2 at a polyacrylonitrile-based activated carbon fiber (ACF cathode. Three cathode materials (i.e., platinum, graphite, and ACF were fed with oxygen and used for the electrogeneration of H2O2. The amount of electrogenerated H2O2 produced using the ACF cathode was five times greater than that generated using the graphite cathode and nearly 24 times greater than that from platinum cathode. Several parameters were evaluated to characterize the H2O2 electrogeneration, such as current density, oxygen flow rate, solution pH, and the supporting electrolyte used. The optimum current density, oxygen flow rate, solution pH, and supporting electrolyte composition were found to be 10 mA cm−2, 500 cm3 min−1, pH 3, and Na2SO4, respectively. The PVA removal efficiencies were achieved under these conditions 3%, 16%, and 86% using UV, H2O2 electrogeneration, and UV/H2O2 electrogeneration, respectively. A UV light intensity of 0.6 mW cm−2 was found to produce optimal PVA removal efficiency in the present study. A simple kinetic model was proposed which confirmed pseudo-first-order reaction. Reaction rate constant (kap was found to depend on the UV light intensity.

  7. Amperometric Non-Enzymatic Hydrogen Peroxide Sensor Based on Aligned Zinc Oxide Nanorods

    Directory of Open Access Journals (Sweden)

    Naif H. Al-Hardan

    2016-06-01

    Full Text Available Zinc oxide (ZnO nanorods (NRs have been synthesized via the hydrothermal process. The NRs were grown over a conductive glass substrate. A non-enzymatic electrochemical sensor for hydrogen peroxide (H2O2, based on the prepared ZnO NRs, was examined through the use of current-voltage measurements. The measured currents, as a function of H2O2 concentrations ranging from 10 μM to 700 μM, revealed two distinct behaviours and good performance, with a lower detection limit (LOD of 42 μM for the low range of H2O2 concentrations (first region, and a LOD of 143.5 μM for the higher range of H2O2 concentrations (second region. The prepared ZnO NRs show excellent electrocatalytic activity. This enables a measurable and stable output current. The results were correlated with the oxidation process of the H2O2 and revealed a good performance for the ZnO NR non-enzymatic H2O2 sensor.

  8. Hypersensitivity of mouse NEIL1-knockdown cells to hydrogen peroxide during S phase

    International Nuclear Information System (INIS)

    Oxidative base damage occurs spontaneously due to reactive oxygen species generated as byproducts of respiration and other pathological processes in mammalian cells. Many oxidized bases are mutagenic and/or toxic, and most are repaired through the base excision repair pathway. Human endonuclease VIII-like protein 1 (hNEIL1) is thought to play an important role during the S phase of the cell cycle by removing oxidized bases in DNA replication fork-like (bubble) structures, and the protein level of hNEIL1 is increased in S phase. Compared with hNEIL1, there is relatively little information on the properties of the mouse ortholog mNEIL1. Since mouse cell nuclei lack endonuclease III-like protein (NTH) activity, in contrast to human cell nuclei, mNEIL1 is a major DNA glycosylase for repair of oxidized pyrimidines in mouse nuclei. In this study, we made mNEIL1-knockdown cells using an shRNA expression vector and examined the cell cycle-related variation in hydrogen peroxide (H2O2) sensitivity. Hypersensitivity to H2O2 caused by mNEIL1 knockdown was more significant in S phase than in G1 phase, suggesting that mNEIL1 has an important role during S phase, similarly to hNEIL1

  9. Role of mitochondrial hydrogen peroxide induced by intermittent hypoxia in airway epithelial wound repair in vitro.

    Science.gov (United States)

    Hamada, Satoshi; Sato, Atsuyasu; Hara-Chikuma, Mariko; Satooka, Hiroki; Hasegawa, Koichi; Tanimura, Kazuya; Tanizawa, Kiminobu; Inouchi, Morito; Handa, Tomohiro; Oga, Toru; Muro, Shigeo; Mishima, Michiaki; Chin, Kazuo

    2016-05-15

    The airway epithelium acts as a frontline barrier against various environmental insults and its repair process after airway injury is critical for the lung homeostasis restoration. Recently, the role of intracellular reactive oxygen species (ROS) as transcription-independent damage signaling has been highlighted in the wound repair process. Both conditions of continuous hypoxia and intermittent hypoxia (IH) induce ROS. Although IH is important in clinical settings, the roles of IH-induced ROS in the airway repair process have not been investigated. In this study, we firstly showed that IH induced mitochondrial hydrogen peroxide (H2O2) production and significantly decreased bronchial epithelial cell migration, prevented by catalase treatment in a wound scratch assay. RhoA activity was higher during repair process in the IH condition compared to in the normoxic condition, resulting in the cellular morphological changes shown by immunofluorescence staining: round cells, reduced central stress fiber numbers, pronounced cortical actin filament distributions, and punctate focal adhesions. These phenotypes were replicated by exogenous H2O2 treatment under the normoxic condition. Our findings confirmed the transcription-independent role of IH-induced intracellular ROS in the bronchial epithelial cell repair process and might have significant implications for impaired bronchial epithelial cell regeneration. PMID:27093911

  10. Sunscreens as a source of hydrogen peroxide production in coastal waters.

    Science.gov (United States)

    Sánchez-Quiles, David; Tovar-Sánchez, Antonio

    2014-08-19

    Sunscreens have been shown to give the most effective protection for human skin from ultraviolet (UV) radiation. Chemicals from sunscreens (i.e., UV filters) accumulate in the sea and have toxic effects on marine organisms. In this report, we demonstrate that photoexcitation of inorganic UV filters (i.e., TiO2 and ZnO nanoparticles) under solar radiation produces significant amounts of hydrogen peroxide (H2O2), a strong oxidizing agent that generates high levels of stress on marine phytoplankton. Our results indicate that the inorganic oxide nanoparticle content in 1 g of commercial sunscreen produces rates of H2O2 in seawater of up to 463 nM/h, directly affecting the growth of phytoplankton. Conservative estimates for a Mediterranean beach reveal that tourism activities during a summer day may release on the order of 4 kg of TiO2 nanoparticles to the water and produce an increment in the concentration of H2O2 of 270 nM/day. Our results, together with the data provided by tourism records in the Mediterranean, point to TiO2 nanoparticles as the major oxidizing agent entering coastal waters, with direct ecological consequences on the ecosystem. PMID:25069004

  11. Kansas City plant ultraviolet/ozone/hydrogen peroxide groundwater treatment system overview

    International Nuclear Information System (INIS)

    The Kansas City Plant (KCP) has committed to the utilization of a groundwater treatment system, for removal of volatile organic compounds (VOCs), that discharges a minimal amount of pollutants to the environment. An advanced oxidation process (AOP) system utilizing ozone, ultraviolet radiation, and hydrogen peroxide serves in this capacity. Packed tower aeration and activated carbon filtration are listed as best available technologies (BATs) by the Environmental Protection Agency (EPA) for the removal of VOCs in water. The disadvantage to these BATs is that they transfer the VOCs from the water medium to the air or carbon media respectively. Operation of the system began in May 1988 at a flow rate of 22.7 liters per minute (lpm) (6 gallons per minute (gpm)). An additional 102.2 lpm (27 gpm) of flow were added in October 1990. Various efforts to optimize and track the treatment unites efficiency have been carried out. A maximum influent reading of 26,590 parts per billion (ppb) of total VOCs has been recorded. Following the addition of flows, removal efficiency has averaged approximately 95%. Both air and water effluents are factored into this calculation. (author)

  12. Astaxanthin Protects Steroidogenesis from Hydrogen Peroxide-Induced Oxidative Stress in Mouse Leydig Cells

    Directory of Open Access Journals (Sweden)

    Jyun-Yuan Wang

    2015-03-01

    Full Text Available Androgens, especially testosterone produced in Leydig cells, play an essential role in development of the male reproductive phenotype and fertility. However, testicular oxidative stress may cause a decline in testosterone production. Many antioxidants have been used as reactive oxygen species (ROS scavengers to eliminate oxidative stress to protect steroidogenesis. Astaxanthin (AST, a natural extract from algae and plants ubiquitous in the marine environment, has been shown to have antioxidant activity in many previous studies. In this study, we treated primary mouse Leydig cells or MA-10 cells with hydrogen peroxide (H2O2 to cause oxidative stress. Testosterone and progesterone production was suppressed and the expression of the mature (30 kDa form of StAR protein was down-regulated in MA-10 cells by H2O2 and cAMP co-treatment. However, progesterone production and expression of mature StAR protein were restored in MA-10 cells by a one-hour pretreatment with AST. AST also reduced ROS levels in cells so that they were lower than the levels in untreated controls. These results provide additional evidence of the potential health benefits of AST as a potential food additive to ease oxidative stress.

  13. Modulatory effects of Moringa oleifera extracts against hydrogen peroxide-induced cytotoxicity and oxidative damage.

    Science.gov (United States)

    Sreelatha, S; Padma, P R

    2011-09-01

    Studies have demonstrated that the induction of oxidative stress may be involved in oxidative DNA damage. The present study examined and assessed the hydrogen peroxide (H(2)O(2))-mediated DNA damage in human tumor KB cells and also assessed the ability of Moringa oleifera leaf extracts to inhibit the oxidative damage. H(2)O(2) imposed a stress on the membrane lipids which was quantified by the extent of thiobarbituric acid reactive substances (TBARS) formed. The leaf extracts caused a very significant inhibition of the extent of LPO formation and enhanced the activity of antioxidative enzymes such as superoxide dismutase (SOD) and catalase (CAT) in KB cells. The comet assay was employed to study the DNA damage and its inhibition by the leaf extracts. H(2)O(2) caused a significant increase in the number of cells bearing comets, resulting in significant DNA damage. The leaf extracts significantly reduced the incidence of comets in the oxidant stressed cells. The extent of cytotoxicity of H(2)O(2) in the presence and the absence of leaf extracts studied in KB tumor cells by the MTT assay showed that H(2)O(2) caused a marked decrease in the viability of KB cells where as the leaf extracts effectively increased the viability of assaulted KB cells. The observed cytoprotective activity is probably due to the antioxidant properties of its constituents, mainly phenolics. Total phenolics showed higher correlation with antioxidant activity. The leaf extracts showed higher antioxidant activity than the reference compound. These results suggest that the inhibition by the leaf extracts on oxidative DNA damage could be attributed to their free radical scavenging activities and the effect evidenced in KB cells can be in part correlated to a modulation of redox-sensitive mechanisms.

  14. Shear Bond Strength of Resin Bonded to Bleached Enamel Using Different Modified 35% Hydrogen Peroxides

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    Moosavi H

    2015-12-01

    Full Text Available Statement of Problem: Bleaching systems with different concentrations and applications are widely used to improve the visual appearance of the teeth, but one of the complications of these materials is reduction of bond strength for immediately bonding to the bleached enamel. Objectives: The aim of this study was to evaluate the influence of using different modified hydrogen peroxide bleaching agents on the shear bond strength of composite resin bonded to the bleached enamel. Materials and Methods: Forty-eight sound extracted premolar teeth were collected, sectioned 1 mm below the CEJ to detach the root. The proximal surfaces of the teeth were flattened using diamond disks and silicon carbide papers to achieve flat homogeneous enamel surfaces without exposure to the dentin. The teeth were randomly divided into four groups as follows (n = 12: group 1: bleaching with 35% hydrogen peroxide gel; group 2: bleaching with 35% hydrogen peroxide gel contained (casein phosphopeptide-amorphous calcium phosphate (CPP-ACP; group 3: bleaching with 35% hydrogen peroxide gel combined with fluoride; and group 4: bleaching with 35% hydrogen peroxide applying one week before resin restoration placement. Composite resin, Clearfil AP-X (Kuraray, Tokyo, Japan, was bonded on each tooth in the mould (4 mm diameter × 3 mm height using Clearfil SE Bond (Kuraray, Tokyo, Japan. After 24 hours of storage and 1000 cycles of thermocycling, the shear bond strength of the specimens at a cross-head speed of 0.5 mm/min was measured in MPa. Data were analyzed using ANOVA and Tukey’s post-hoc test. Results: The minimum and maximum mean shear bond strength values were observed in groups 2 (15.82 ± 4.41 and 4 (21.00 ± 3.90, respectively. Multiple comparisons of groups revealed no significant differences among the groups except between group 4 and all the other groups. The most common type of failure was adhesive. Conclusions: Using modified bleaching agents decreased the bond

  15. Simultaneous removal of nitrate, hydrogen peroxide and phosphate in semiconductor acidic wastewater by zero-valent iron.

    Science.gov (United States)

    Yoshino, Hiroyuki; Tokumura, Masahiro; Kawase, Yoshinori

    2014-01-01

    The zero-valent iron (ZVI) wastewater treatment has been applied to simultaneous removal of nitrate, hydrogen peroxide and phosphate in semiconductor acidic wastewaters. The simultaneous removal occurs by the reactions performed due to the sequential transformation of ZVI under the acidic condition. Fortunately the solution pH of semiconductor acidic wastewaters is low which is effective for the sequential transformation of ZVI. Firstly the reduction of nitrate is taken place by electrons generated by the corrosion of ZVI under acidic conditions. Secondly the ferrous ion generated by the corrosion of ZVI reacts with hydrogen peroxide and generates ·OH radical (Fenton reaction). The Fenton reaction consists of the degradation of hydrogen peroxide and the generation of ferric ion. Finally phosphate precipitates out with iron ions. In the simultaneous removal process, 1.6 mM nitrate, 9.0 mM hydrogen peroxide and 1.0 mM phosphate were completely removed by ZVI within 100, 15 and 15 min, respectively. The synergy among the reactions for the removal of nitrate, hydrogen peroxide and phosphate was found. In the individual pollutant removal experiment, the removal of phosphate by ZVI was limited to 80% after 300 min. Its removal rate was considerably improved in the presence of hydrogen peroxide and the complete removal of phosphate was achieved after 15 min.

  16. Oxidative stress response of Inonotus obliquus induced by hydrogen peroxide.

    Science.gov (United States)

    Zheng, Weifa; Zhao, Yanxia; Zhang, Meimei; Wei, Zhiwen; Miao, Kangjie; Sun, Weiguo

    2009-12-01

    While the medicinal fungus Inonotus obliquus produces polyphenols as one of its main metabolites in natural habitats, it accumulates less polyphenols under laboratory conditions. In this study we found that the continuous addition of 1 mM H(2)O(2) at a rate of 1.6 ml/h into a submerged culture of the fungus enhanced its production of mycelia, melanins, flavonoids and hispidin analogs (HA). Simultaneous exposure of the fungus to both H(2)O(2) and arbutin resulted in reduced production of mycelia, glycosylated flavonoids (GF) and HA, and inhibition of melanogenesis. However, superoxide dismutases (SOD) and catalase (CAT) activity were enhanced following the addition of H(2)O(2) or H(2)O(2) plus arbutin. The maximum levels of SOD and CAT activities reached 355.2 U/mg protein and 39.8 U/mg protein respectively in H(2)O(2)-added medium, and 264 U/mg protein and 35.9 U/mg protein respectively in H(2)O(2) plus arbutin medium. Thus, detoxification of H(2)O(2) is conducted mainly by polyphenols under normal physiological conditions, and by both polyphenols and antioxidant enzymes under oxidative stress when melanogenesis is inhibited. Although enhanced HA production occurred after melanogenesis inactivation, total extracellular polyphenol levels were reduced. These findings suggest that enzymatic activities convert superoxide to H(2)O(2), and non-enzymatic mechanisms are largely responsible for detoxifying H(2)O(2). Enhanced production of melanins is the most important non-enzymatic response of this fungus against oxidative stress. PMID:19184774

  17. Protective effect of total phenolic compounds from inula helenium on hydrogen peroxide-induced oxidative stress in sh-sy5y cells

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    J Wang

    2015-01-01

    Full Text Available Inula helenium has been reported to contain a large amount of phenolic compounds, which have shown promise in scavenging free radicals and prevention of neurodegenerative diseases. This study is to investigate the neuroprotective effects of total phenolic compounds from I. helenium on hydrogen peroxide-induced oxidative damage in human SH-SY5Y cells. Antioxidant capacity of total phenolic compounds was determined by radical scavenging activity, the level of intracellular reactive oxygen species and superoxide dismutase activity. The cytotoxicity of total phenolic compounds was determined using a cell counting kit-8 assay. The effect of total phenolic compounds on cell apoptosis due to hydrogen peroxide-induced oxidative damage was detected by Hoechst 33258 and Annexin-V/PI staining using fluorescence microscope and flow cytometry, respectively. Mitochondrial function was evaluated using the mitochondrial membrane potential and mitochondrial ATP synthesis by JC-1 dye and high performance liquid chromatography, respectively. It was shown that hydrogen peroxide significantly induced the loss of cell viability, increment of apoptosis, formation of reactive oxygen species, reduction of superoxide dismutase activity, decrease in mitochondrial membrane potential and a decrease in adenosine triphosphate production. On the other hand, total phenolic compounds dose-dependently reversed these effects. This study suggests that total phenolic compounds exert neuroprotective effects against hydrogen peroxide-induced oxidative damage via blocking reactive oxygen species production and improving mitochondrial function. The potential of total phenolic compounds and its neuroprotective mechanisms in attenuating hydrogen peroxide-induced oxidative stress-related cytotoxicity is worth further exploration.

  18. Effects on gastric mucosa induced by dental bleaching – an experimental study with 6% hydrogen peroxide in rats

    Directory of Open Access Journals (Sweden)

    Anabela Baptista PAULA

    2015-10-01

    Full Text Available The value of aesthetic dentistry has precipitated several developments in the investigation of dental materials related to this field. The free marketing of these products is a problem and it is subject to various interpretations regarding its legality. There are several techniques for tooth whitening, the most used one being the external bleaching. It is the later version of such technique that poses the greatest danger of ingesting the product. The present study analysed the systemic effect of these products when they are swallowed.Objective This experimental study aimed to observe the effects of a tooth whitening product, whose active agent is 6% hydrogen peroxide, on the gastric mucosa of healthy and non-tumour gastric pathology animals.Material and Methods Fifty Wistar-Han rats were used and then distributed into 5 groups, one for control and four test groups in which the bleaching product was administered in animals with and without non-tumour gastric pathology (induced by the administration of 1 sample of 50% ethanol and 5% of drinking water during 6 days at different times of study by gavage. There was a decrease in body weight in animals of groups handled during the study period, which was most pronounced in IV and VA groups. Changes in spleen weight relative to body weight revealed no statistically significant changes. An analysis of the frequency was performed on the results of macroscopic observation of the gastric mucosa.Results The gastric mucosa revealed lesions in all manipulated groups, being more frequent in groups III and IV. It appears that there is a synergism when using hydrogen peroxide and 50% ethanol in the same group.Conclusion Therefore, it seems that there are some signs of toxicity 3 to 4 days after administration of 6% hydrogen peroxide. The prescription of these therapies must be controlled by the clinician and the risks must be minimized.

  19. Enzyme-free hydrogen peroxide sensor based on Au@Ag@C core-double shell nanocomposites

    Energy Technology Data Exchange (ETDEWEB)

    Li, Yancai, E-mail: liyancai@mnnu.edu.cn [College of Chemistry & Environment, Minnan Normal University, Zhangzhou 363000 (China); Fujian Province Key Laboratory of Modern Analytical Science and Separation Technology, Minnan Normal University, Zhangzhou 363000 (China); Zhang, Yayun; Zhong, Yanmei [College of Chemistry & Environment, Minnan Normal University, Zhangzhou 363000 (China); Li, Shunxing [College of Chemistry & Environment, Minnan Normal University, Zhangzhou 363000 (China); Fujian Province Key Laboratory of Modern Analytical Science and Separation Technology, Minnan Normal University, Zhangzhou 363000 (China)

    2015-08-30

    Graphical abstract: - Highlights: • A facile method was designed to synthesize Au@Ag@C core-double shell nanocomposites. • Carbon nanomaterials at the outermost layer could protect Au and Ag nanoparticles from oxidation and aggregation. • The Au@Ag@C core-double shell nanocomposites showed high sensitivity and selectivity to electrocatalytic reduction of hydrogen peroxide. • The hydrogen peroxide sensor has a wide linear range of 5.0 μM to 4.75 mM and a limit of detection as low as 0.14 μM. - Abstract: The well-designed Au@Ag@C core-double shell nanocomposites were synthesized via a facile method, and were used to fabricate an enzyme-free amperometric hydrogen peroxide (H{sub 2}O{sub 2}) sensor. The size, shape, elementary composition and structure of the nanocomposites were characterized by transmission electron microscope (TEM), energy-dispersed spectrum (EDS) and X-ray diffraction (XRD). The outermost layer of the nanocomposites was amorphous carbon, the second layer was Ag and the core was Au. The Au@Ag@C core-double shell nanocomposites exhibit attractive activity for electrocatalytic reduction of H{sub 2}O{sub 2} according to the electrochemical experiments. It also demonstrates the H{sub 2}O{sub 2} sensor possess well performance with a wide linear range of 5.0 μM to 4.75 mM and a limit of detection (LOD) as low as 0.14 μM (S/N = 3). Furthermore, the interference from the common interfering species, such as glucose, ascorbic acid, dopamine and uric acid can be effectively avoided. In a word, the Au@Ag@C nanocomposites are promising candidates for enzyme-free H{sub 2}O{sub 2} sensor.

  20. Hydrogen peroxide route to Sn-doped titania photocatalysts

    Directory of Open Access Journals (Sweden)

    Štengl Václav

    2012-10-01

    Full Text Available Abstract Background The work aims at improving photocatalytic activity of titania under Vis light irradiation using modification by Sn ions and an original, simple synthesis method. Tin-doped titania catalysts were prepared by thermal hydrolysis of aqueous solutions of titanium peroxo-complexes in the presence of SnCl4 or SnCl2 using an original, proprietary "one pot" synthesis not employing organic solvents, metallo-organic precursors, autoclave aging nor post-synthesis calcination. The products were characterized in details by powder diffraction, XPS, UV–vis, IR, and Raman spectroscopies, electron microscopy and surface area and porosity measurements Results The presence of tin in synthesis mixtures favors the formation of rutile and brookite at the expense of anatase, decreases the particle size of all formed titania polymorphs, and extends light absorption of titania to visible light region >400 nm by both red shift of the absorption edge and introduction of new chromophores. The photocatalytic activity of titania under UV irradiation and >400 nm light was tested by decomposition kinetics of Orange II dye in aqueous solution Conclusions Doping by Sn improves titania photoactivity under UV light and affords considerable photoactivity under >400 nm light due to increased specific surface area and a phase heterogeneity of the Sn-doped titania powders.

  1. Detection of Hydrogen Peroxide Photogenerating from a Hypocrellin B Derivative

    Institute of Scientific and Technical Information of China (English)

    刘光艳; 马江华

    2003-01-01

    In order to further improve the photosensitizing activity of hypocrellin B (HB), the complex of 5,8-diBr-HB with Al3 + was designed and synthesized in high yield. The complex of aluminium ion with 5,8-di-Br-HB is a new water-soluble perylenequinonoid derivative with enhanced absorption over HB in the phototherapeutic window (600-900 nm). Electron paramagnetic resonance (EPR) measurement and 9,10-diphenyl-anthracene bleaching methods were used to investigate the photosensitizing activity of [ Al2 ( 5,8-di-Br-HB ) Cl4 ]n in the presence of oxygen. Singlet oxygen, superoxide anion radical, hydroxyl radical can be generated by [ Al2 (5,8-di-Br-HB) Cl4 ]n photosensitization. The results showed that the production of hydroxyl radical (*OH) by [ Al2 (5,8-di-Br-HB) Cl4 ] n photosensitization comes from the Fenton Haber-Weiss reaction and the decomposition of DMPO-1O2 adduct. Formation of H2 O2 as one of main intermediates in the photogeneration of hydroxyl radical was detected by using the catalyzed oxidation of the DPD reagent by the POD enzyme method. Moreover, the experiments of EPR spin trap and catalase enzyme excluded the effect of organoperoxide on DPD oxidization. These results further support the proposed mechanism of *OH formation.

  2. Protective effect of oat bran extracts on human dermal fibroblast injury induced by hydrogen peroxide

    Institute of Scientific and Technical Information of China (English)

    Bing FENG; Lai-ji MA; Jin-jing YAO; Yun FANG; Yan-ai MEI; Shao-min WEI

    2013-01-01

    Oat contains different components that possess antioxidant properties;no study to date has addressed the antioxidant effect of the extract of oat bran on the cellular level.Therefore,the present study focuses on the investigation of the protective effect of oat bran extract by enzymatic hydrolysates on human dermal fibroblast injury induced by hydrogen peroxide(H2O2).Kjeldahl determination,phenol-sulfuric acid method,and high-performance liquid chromatography(HPLC)analysis indicated that the enzymatic products of oat bran contain a protein amount of 71.93%,of which 97.43% are peptides with a molecular range from 438.56 to 1301.01 Da.Assays for 1,1-diphenyl-2-picrylhydrazyl(DPPH)radical scavenging activity indicate that oat peptide-rich extract has a direct and concentration-dependent antioxidant activity.3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide(MTT)colorimetric assay and the TdT-mediated digoxigenin-dUTP nick-end labeling(TUNEL)assay for apoptosis showed that administration of H2O2 in human dermal fibroblasts caused cell damage and apoptosis.Pre-incubation of human dermal fibroblasts with the Oatp for 24 h markedly inhibited human dermal fibroblast injury induced by H2O2,but application oat peptides with H2O2 at same time did not.Pre-treatment of human dermal fibroblasts with Oatp significantly reversed the H2O2-induced decrease of superoxide dismutase(SOD)and the inhibition of malondialdehyde(MDA).The results demonstrate that oat peptides possess antioxidant activity and are effective against H2O2-induced human dermal fibroblast injury by the enhanced activity of SOD and decrease in MDA level.Our results suggest that oat bran will have the potential to be further explored as an antioxidant functional food in the prevention of aging-related skin injury.

  3. Use of hydrogen peroxide in scrubbing towers for odor removal in wastewater treatment plants.

    Science.gov (United States)

    Charron, I; Féliers, C; Couvert, A; Laplanche, A; Patria, L; Requieme, B

    2004-01-01

    The aim of this work was to replace sodium hypochlorite (NaCIO) with hydrogen peroxide (H202) in chemical scrubbing towers, in order to avoid the formation of chlorinated species, harmful for human health. Some previous studies have already shown the ability of H2O2 to treat the hydrogen sulfide (H2S) pollution. However, an important decomposition of the oxidant was observed in the scrubbing solution (carbonates, transition metal and high pH are responsible for this decomposition) leading to high reactant consumption. Consequently, this study first focused on research into a compound able to reduce the hydrogen peroxide degradation. Experiments were conducted on a pilot unit (3,000 m3 h(-1)) in a wastewater treatment plant. The sodium silicate (Na2SiO3) proved to be a good scrubbing solution stabilizer. A very good removal of hydrogen sulfide (up to 98%) was also obtained. Finally, the study resulted in the determination of the best operating conditions to achieve both an efficient and economical process.

  4. Hydrogen peroxide affects ion channels in lily pollen grain protoplasts.

    Science.gov (United States)

    Breygina, M A; Abramochkin, D V; Maksimov, N M; Yermakov, I P

    2016-09-01

    Ion homeostasis plays a central role in polarisation and polar growth. In several cell types ion channels are controlled by reactive oxygen species (ROS). One of the most important cells in the plant life cycle is the male gametophyte, which grows under the tight control of both ion fluxes and ROS balance. The precise relationship between these two factors in pollen tubes has not been completely elucidated, and in pollen grains it has never been studied to date. In the present study we used a simple model - protoplasts obtained from lily pollen grains at the early germination stage - to reveal the effect of H2 O2 on cation fluxes crucial for pollen germination. Here we present direct evidence for two ROS-sensitive currents on the pollen grain plasma membrane: the hyperpolarisation-activated calcium current, which is strongly enhanced by H2 O2 , and the outward potassium current, which is modestly enhanced by H2 O2 . We used low concentrations of H2 O2 that do not cause an intracellular oxidative burst and do not damage cells, as demonstrated with fluorescent staining. PMID:27115728

  5. Hydrogen peroxide homeostasis and signaling in plant cells

    Institute of Scientific and Technical Information of China (English)

    CHENG; Yanli; SONG; Chunpen

    2006-01-01

    The increases of H2O2 concentrations in plant cells often occur under biotic and abiotic stress conditions (e.g. light, environmental stresses and plant hormone abscisic acid).Atmospheric H2O2 as an ancient signal molecule not only plays the key role in inducing evolution of oxygenic photosynthesis, but also modulates many physiological events, such as stomatal movement, hypersensitive responses, programmed cell death and gene expressions. H2O2 levels in cells must sustain a fine equilibrium between production and scavenging. H2O2 enters cells from the apoplast or generated sources, and in turn is distributed in sub-cellular compartments.H2O2 can modulate the activities of many components in signaling, such as protein phosphatases,protein kinases, transcription factors (TFs), and calcium channels. Elevated cytosolic calcium concentrations will initiate further downstream responses, via the action of calcium-binding proteins. On the other hand, the research of H2O2 as a signal molecule is still in a comparatively juvenile stage, for example, little is known about how the cells sense H2O2, what the rate-limiting steps and most important cellular events are in cell signaling and what kind of genes is specific or necessary to H2O2 signaling. The answers to all the questions depend on the functional genomic and molecular genetics analysis.

  6. Chemo-enzymatic epoxidation of olefins by carboxylic acid esters and hydrogen peroxide

    Energy Technology Data Exchange (ETDEWEB)

    Ruesch gen. Klaas, M.; Warwel, S. [Inst. for Biochemistry and Technology of Lipids, H.P. Kaufmanm-Inst., Federal Centre for Cereal, Potato and Lipid Research, Muenster (Germany)

    1998-12-31

    Ethylen and, recently, butadiene can be epoxidized directly with oxygen and for the epoxidation of propylene, the use of heterogeneous transition metals and organic peroxides (Halcon-Process) is the major player. But, beside from those notable exceptions, all other epoxidations, including large ones like the epoxidation of plant oils as PVC-stabilizers (about 200.000 t/year), are carried out with peroxy acids. Because mcpba is far to expensive for most applications, short chain peracids like peracetic acid are used. Being much less stable than mcpba and thus risky handled in large amounts and high concentrations, these peroxy acids were preferably prepared in-situ. However, conventional in-situ formation of peracids has the serious drawback, that a strong acid is necessary to catalyze peroxy acid formation from the carboxylic acid and hydrogen peroxide. The presence of a strong acid in the reaction mixture often results in decreased selectivity because of the formation of undesired by-products by opening of the oxirane ring. Therefore, we propose a new method for epoxidation based on the in-situ preparation of percarboxylic acids from carboxylic acid esters and hydrogen peroxide catalyzed by a commercial, immobilized lipase. (orig.)

  7. Aldehydes, hydrogen peroxide, and organic radicals as mediators of ozone toxicity

    Energy Technology Data Exchange (ETDEWEB)

    Pryor, W.A.; Church, D.F. (Biodynamics Institute, Louisiana State University, Baton Rouge (United States))

    1991-01-01

    It is generally agreed that unsaturated fatty acids (UFA) are an important class of target molecule for reaction with ozone when polluted air is inhaled. Most discussions have implicated the UFA in cell membranes, but lung lining fluids also contain fatty acids that are from 20 to 40% unsaturated. Since UFA in lung lining fluids exist in a highly aquated environment, ozonation would be expected to produce aldehydes and hydrogen peroxide, rather than the Criegee ozonide. In agreement with this expectation, the authors find that ozonations of emulsions of fatty acids containing from one to four double bonds give one mole of H2O2 for each mole of ozone reacted. Ozonation of oleic acid emulsions and dioleoyl phosphatidyl choline gives similar results, with two moles of aldehydes and one mole of H2O2 formed per mole of ozone reacted. The net reaction that occurs when ozone reacts with pulmonary lipids is suggested to be given by equation 1. (formula: see text). From 5 to 10% yields of Criegee ozonides also appear to be formed. In addition, a direct reaction of unknown mechanism occurs between ozone and UFA in homogeneous organic solution, in homogeneous solutions in water, in aqueous emulsions, and in lipid bilayers to give organic radicals that can be spin trapped. These radicals are suggested to be responsible for initiating lipid peroxidation of polyunsaturated fatty acids. Thus, aldehydes, hydrogen peroxide, and directly produced organic radicals are suggested to be mediators of ozone-induced pathology.39 references.

  8. In vitro and in vivo evaluation of SLA titanium surfaces with further alkali or hydrogen peroxide and heat treatment

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, E W; Wang, Y B; Zheng, Y F [State Key Laboratory for Turbulence and Complex System, Department of Advanced Materials and Nanotechnology, College of Engineering, Peking University, Beijing 100871 (China); Shuai, K G; Gao, F; Bai, Y J; Cheng, Y; Xiong, X L [Center for Biomedical Materials and Tissue Engineering, Academy for Advanced Interdisciplinary Studies, Peking University, Beijing 100871 (China); Wei, S C, E-mail: enwei@pku.edu.cn, E-mail: yanbo.pku@pku.edu.cn, E-mail: shuaikegang@gmail.com, E-mail: soarfgoal@gmail.com, E-mail: norice86@163.com, E-mail: chengyan@pku.edu.cn, E-mail: xxiaoling11@hotmail.com, E-mail: yfzheng@pku.edu.cn, E-mail: weishicheng99@163.com [Department of Oral and Maxillofacial Surgery, School of Stomatology, Peking University, Beijing 100081 (China)

    2011-04-15

    The present study aimed to evaluate the bioactivity of titanium surfaces sandblasted with large-grit corundum and acid etched (SLA) plus further alkali or hydrogen peroxide and heat treatment for dental implant application. Pure titanium disks were mechanically polished as control surface (Ti-control) and then sandblasted with large-grit corundum and acid etched (SLA). Further chemical modifications were conducted using alkali and heat treatment (ASLA) and hydrogen peroxide and heat treatment (HSLA) alternatively. The surface properties were characterized by scanning electron microscopy (SEM), x-ray photoelectron spectroscopy (XPS), and contact angle and roughness measurements. Further evaluation of surface bioactivity was conducted by MC3T3-E1 cell attachment, proliferation, morphology, alkaline phosphatase (ALP) activity and calcium deposition on the sample surfaces. After insertion in the beagle's mandibula for a specific period, cylindrical implant samples underwent micro-CT examination and then histological examination. It was found that ASLA and HSLA surfaces significantly increased the surface wettability and MC3T3-E1 cell attachment percentage, ALP activity and the quality of calcium deposition in comparison with simple SLA and Ti-control surfaces. Animal studies showed good osseointegration of ASLA and HSLA surfaces with host bone. In conclusion, ASLA and HSLA surfaces enhanced the bioactivity of the traditional SLA surface by integrating the advantages of surface topography, composition and wettability.

  9. In vitro and in vivo evaluation of SLA titanium surfaces with further alkali or hydrogen peroxide and heat treatment.

    Science.gov (United States)

    Zhang, E W; Wang, Y B; Shuai, K G; Gao, F; Bai, Y J; Cheng, Y; Xiong, X L; Zheng, Y F; Wei, S C

    2011-04-01

    The present study aimed to evaluate the bioactivity of titanium surfaces sandblasted with large-grit corundum and acid etched (SLA) plus further alkali or hydrogen peroxide and heat treatment for dental implant application. Pure titanium disks were mechanically polished as control surface (Ti-control) and then sandblasted with large-grit corundum and acid etched (SLA). Further chemical modifications were conducted using alkali and heat treatment (ASLA) and hydrogen peroxide and heat treatment (HSLA) alternatively. The surface properties were characterized by scanning electron microscopy (SEM), x-ray photoelectron spectroscopy (XPS), and contact angle and roughness measurements. Further evaluation of surface bioactivity was conducted by MC3T3-E1 cell attachment, proliferation, morphology, alkaline phosphatase (ALP) activity and calcium deposition on the sample surfaces. After insertion in the beagle's mandibula for a specific period, cylindrical implant samples underwent micro-CT examination and then histological examination. It was found that ASLA and HSLA surfaces significantly increased the surface wettability and MC3T3-E1 cell attachment percentage, ALP activity and the quality of calcium deposition in comparison with simple SLA and Ti-control surfaces. Animal studies showed good osseointegration of ASLA and HSLA surfaces with host bone. In conclusion, ASLA and HSLA surfaces enhanced the bioactivity of the traditional SLA surface by integrating the advantages of surface topography, composition and wettability. PMID:21293055

  10. In vitro and in vivo evaluation of SLA titanium surfaces with further alkali or hydrogen peroxide and heat treatment.

    Science.gov (United States)

    Zhang, E W; Wang, Y B; Shuai, K G; Gao, F; Bai, Y J; Cheng, Y; Xiong, X L; Zheng, Y F; Wei, S C

    2011-04-01

    The present study aimed to evaluate the bioactivity of titanium surfaces sandblasted with large-grit corundum and acid etched (SLA) plus further alkali or hydrogen peroxide and heat treatment for dental implant application. Pure titanium disks were mechanically polished as control surface (Ti-control) and then sandblasted with large-grit corundum and acid etched (SLA). Further chemical modifications were conducted using alkali and heat treatment (ASLA) and hydrogen peroxide and heat treatment (HSLA) alternatively. The surface properties were characterized by scanning electron microscopy (SEM), x-ray photoelectron spectroscopy (XPS), and contact angle and roughness measurements. Further evaluation of surface bioactivity was conducted by MC3T3-E1 cell attachment, proliferation, morphology, alkaline phosphatase (ALP) activity and calcium deposition on the sample surfaces. After insertion in the beagle's mandibula for a specific period, cylindrical implant samples underwent micro-CT examination and then histological examination. It was found that ASLA and HSLA surfaces significantly increased the surface wettability and MC3T3-E1 cell attachment percentage, ALP activity and the quality of calcium deposition in comparison with simple SLA and Ti-control surfaces. Animal studies showed good osseointegration of ASLA and HSLA surfaces with host bone. In conclusion, ASLA and HSLA surfaces enhanced the bioactivity of the traditional SLA surface by integrating the advantages of surface topography, composition and wettability.

  11. In vitro and in vivo evaluation of SLA titanium surfaces with further alkali or hydrogen peroxide and heat treatment

    International Nuclear Information System (INIS)

    The present study aimed to evaluate the bioactivity of titanium surfaces sandblasted with large-grit corundum and acid etched (SLA) plus further alkali or hydrogen peroxide and heat treatment for dental implant application. Pure titanium disks were mechanically polished as control surface (Ti-control) and then sandblasted with large-grit corundum and acid etched (SLA). Further chemical modifications were conducted using alkali and heat treatment (ASLA) and hydrogen peroxide and heat treatment (HSLA) alternatively. The surface properties were characterized by scanning electron microscopy (SEM), x-ray photoelectron spectroscopy (XPS), and contact angle and roughness measurements. Further evaluation of surface bioactivity was conducted by MC3T3-E1 cell attachment, proliferation, morphology, alkaline phosphatase (ALP) activity and calcium deposition on the sample surfaces. After insertion in the beagle's mandibula for a specific period, cylindrical implant samples underwent micro-CT examination and then histological examination. It was found that ASLA and HSLA surfaces significantly increased the surface wettability and MC3T3-E1 cell attachment percentage, ALP activity and the quality of calcium deposition in comparison with simple SLA and Ti-control surfaces. Animal studies showed good osseointegration of ASLA and HSLA surfaces with host bone. In conclusion, ASLA and HSLA surfaces enhanced the bioactivity of the traditional SLA surface by integrating the advantages of surface topography, composition and wettability.

  12. The oxidation of yeast alcohol dehydrogenase-1 by hydrogen peroxide in vitro.

    Science.gov (United States)

    Men, Lijie; Wang, Yinsheng

    2007-01-01

    Yeast alcohol dehydrogenase (YADH) plays an important role in the conversion of alcohols to aldehydes or ketones. YADH-1 is a zinc-containing protein, and it accounts for the major part of ADH activity in growing baker's yeast. To gain insight into how oxidative modification of the enzyme affects its function, we exposed YADH-1 to hydrogen peroxide in vitro and assessed the oxidized protein by LC-MS/MS analysis of proteolytic cleavage products of the protein and by measurements of enzymatic activity, zinc release, and thiol/thiolate loss. The results illustrated that Cys43 and Cys153, which reside at the active site of the protein, could be selectively oxidized to cysteine sulfinic acid (Cys-SO2H) and cysteine sulfonic acid (Cys-SO3H). In addition, H2O2 induced the formation of three disulfide bonds: Cys43-Cys153 in the catalytic domain, Cys103-Cys111 in the noncatalytic zinc center, and Cys276-Cys277. Therefore, our results support the notion that the oxidation of cysteine residues in the zinc-binding domain of proteins can go beyond the formation of disulfide bond(s); the formation of Cys-SO2H and Cys-SO3H is also possible. Furthermore, most methionines could be oxidized to methionine sulfoxides. Quantitative measurement results revealed that, among all the cysteine residues, Cys43 was the most susceptible to H2O2 oxidation, and the major oxidation products of this cysteine were Cys-SO2H and Cys-SO3H. The oxidation of Cys43 might be responsible for the inactivation of the enzyme upon H2O2 treatment.

  13. Hydrogen peroxide and ecdysone in the cryoprotective dehydration strategy of Megaphorura arctica (Onychiuridae: Collembola).

    Science.gov (United States)

    Grubor-Lajšić, Gordana; Petri, Edward T; Kojić, Danijela; Purać, Jelena; Popović, Zeljko D; Worland, Roger M; Clark, Melody S; Mojović, Miloš; Blagojević, Duško P

    2013-02-01

    The Arctic springtail, Megaphorura arctica, survives sub-zero temperatures in a dehydrated state via trehalose-dependent cryoprotective dehydration. Regulation of trehalose biosynthesis is complex; based in part on studies in yeast and fungi, its connection with oxidative stress caused by exposure of cells to oxidants, such as hydrogen peroxide (H₂O₂), or dehydration, is well documented. In this respect, we measured the amount of H₂O₂ and antioxidant enzyme activities (superoxide dismutases: copper, zinc--CuZnSOD and manganese containing--MnSOD, and catalase--CAT), as the regulatory components determining H₂O₂ concentrations, in Arctic springtails incubated at 5 °C (control) versus -2 °C (threshold temperature for trehalose biosynthesis). Because ecdysone also stimulates trehalose production in insects and regulates the expression of genes involved in redox homeostasis and antioxidant protection in Drosophila, we measured the levels of the active physiological form of ecdysone--20-hydroxyecdysone (20-HE). Significantly elevated H₂O₂ and 20-HE levels were observed in M. arctica incubated at -2 °C, supporting a link between ecdysone, H₂O₂, and trehalose levels during cryoprotective dehydration. CAT activity was found to be significantly lower in M. arctica incubated at -2 °C versus 5 °C, suggesting reduced H₂O₂ breakdown. Furthermore, measurement of the free radical composition in Arctic springtails incubated at 5 °C (controls) versus -2 °C by Electron Paramagnetic Resonance spectroscopy revealed melanin-derived free radicals at -2 °C, perhaps an additional source of H₂O₂. Our results suggest that H₂O₂ and ecdysone play important roles in the cryoprotective dehydration process in M. arctica, linked with the regulation of trehalose biosynthesis. PMID:23143920

  14. Haem oxygenase delays programmed cell death in wheat aleurone layers by modulation of hydrogen peroxide metabolism.

    Science.gov (United States)

    Wu, Mingzhu; Huang, Jingjing; Xu, Sheng; Ling, Tengfang; Xie, Yanjie; Shen, Wenbiao

    2011-01-01

    Haem oxygenase-1 (HO-1) confers protection against a variety of oxidant-induced cell and tissue injury in animals and plants. In this report, it is confirmed that programmed cell death (PCD) in wheat aleurone layers is stimulated by GA and prevented by ABA. Meanwhile, HO activity and HO-1 protein expression exhibited lower levels in GA-treated layers, whereas the hydrogen peroxide (H(2)O(2)) content was apparently increased. The pharmacology approach illustrated that scavenging or accumulating H(2)O(2) either delayed or accelerated GA-induced PCD. Furthermore, pretreatment with the HO-1 specific inhibitor, zinc protoporphyrin IX (ZnPPIX), before exposure to GA, not only decreased HO activity but also accelerated GA-induced PCD significantly. The application of the HO-1 inducer, haematin, and the enzymatic reaction product of HO, carbon monoxide (CO) aqueous solution, both of which brought about a noticeable induction of HO expression, substantially prevented GA-induced PCD. These effects were reversed when ZnPPIX was added, suggesting that HO in vivo played a role in delaying PCD. Meanwhile, catalase (CAT) and ascorbate peroxidase (APX) activities or transcripts were enhanced by haematin, CO, or bilirubin (BR), the catalytic by-product of HO. This enhancement resulted in a decrease in H(2)O(2) production and a delay in PCD. In addition, the antioxidants butylated hydroxytoluene (BHT), dithiothreitol (DTT), and ascorbic acid (AsA) were able not only to delay PCD but also to mimic the effects of haematin and CO on HO up-regulation. Overall, the above results suggested that up-regulation of HO expression delays PCD through the down-regulation of H(2)O(2) production.

  15. Activation of Hydrogen Peroxide by Iron-Containing Minerals and Catalysts in Circumneutral pH Solutions: Implications for ex situ and in situ Treatment of Contaminated Water and Soil

    Science.gov (United States)

    Pham, Anh Le Tuan

    The decomposition of hydrogen peroxide (H2O2) on iron minerals can generate hydroxyl radical (•OH), a strong oxidant capable of transforming a wide range of contaminants. This reaction is critical to ex situ advanced oxidation processes employed in waste treatment systems, as well as in situ chemical oxidation processes used for soil and groundwater remediation. Unfortunately, the process in the ex situ treatment systems is relatively inefficient at circumneutral pH values. In this research, the development of iron-containing catalysts with improved efficiency was investigated. In addition, little is known about the factors that control the performance of in situ treatment systems. Another aim of this dissertation was to elucidate those factors to provide a basis for improving the efficiency of the remediation method. Two types of silica- and alumina-containing iron (hydr)oxide catalysts were synthesized by sol-gel processing techniques (Chapter 2). Relative to iron oxides, such as hematite and goethite, these catalysts were 10 to 80 times more effective in catalyzing the production of •OH from H2O2 under circumneutral conditions. The higher efficiency makes these catalysts promising candidates for ex situ advanced oxidation processes. Moreover, because alumina and silica alter the reactivity of the iron oxides with H2O2, understanding the activity of iron associated with natural aluminosilicates and silica-containing minerals in the subsurface is crucial to explaining the variability of •OH production observed in in situ treatment systems. In addition to the sol-gel technique used in Chapter 2, silica-containing iron (hydr)oxide catalysts were synthesized by immobilizing iron oxide onto mesoporous silica supports, such as SBA-15 (Chapter 5). The iron-containing SBA-15 was 10 times more effective than iron oxides in catalyzing the production of •OH from H2O2. Moreover, this catalyst could be employed for selective oxidation of small organic contaminants

  16. Oxidative stress protection and glutathione metabolism in response to hydrogen peroxide and menadione in riboflavinogenic fungus Ashbya gossypii.

    Science.gov (United States)

    Kavitha, S; Chandra, T S

    2014-11-01

    Ashbya gossypii is a plant pathogen and a natural overproducer of riboflavin and is used for industrial riboflavin production. A few literature reports depict a link between riboflavin overproduction and stress in this fungus. However, the stress protection mechanisms and glutathione metabolism are not much explored in A. gossypii. In the present study, an increase in the activity of catalase and superoxide dismutase was observed in response to hydrogen peroxide and menadione. The lipid peroxide and membrane lipid peroxide levels were increased by H2O2 and menadione, indicating oxidative damage. The glutathione metabolism was altered with a significant increase in oxidized glutathione (GSSG), glutathione peroxidase (GPX), glutathione S transferase (GST), and glutathione reductase (GR) and a decrease in reduced glutathione (GSH) levels in the presence of H2O2 and menadione. Expression of the genes involved in stress mechanism was analyzed in response to the stressors by semiquantitative RT-PCR. The messenger RNA (mRNA) levels of CTT1, SOD1, GSH1, YAP1, and RIB3 were increased by H2O2 and menadione, indicating the effect of stress at the transcriptional level. A preliminary bioinformatics study for the presence of stress response elements (STRE)/Yap response elements (YRE) depicted that the glutathione metabolic genes, stress genes, and the RIB genes hosted either STRE/YRE, which may enable induction of these genes during stress. PMID:25178419

  17. Hydrogen peroxide detection with high specificity in living cells and inflamed tissues

    Science.gov (United States)

    Rong, Lei; Zhang, Chi; Lei, Qi; Hu, Ming-Ming; Feng, Jun; Shu, Hong-Bing; Liu, Yi; Zhang, Xian-Zheng

    2016-01-01

    Hydrogen peroxide (H2O2) detection in biological systems is of significant importance, which act as critical second messenger in fundamental biological processes. Here, we report on a chemoselective fluorescent naphthylimide peroxide probe (NPP) for the H2O2 detection in vitro and in vivo. NPP is a phenylboronic acid-caged chromophore that selectively responds to H2O2 through a self-immolate mechanism. NPP exhibited high sensitivity and selectivity to H2O2 with distinctive fluorescence change due to the excellent two-photon excitation property, which permits the facile detection of inflammation produced H2O2 and offers chance to monitor the inflammatory stages in diseased cells.

  18. Hydrogen peroxide detection with high specificity in living cells and inflamed tissues.

    Science.gov (United States)

    Rong, Lei; Zhang, Chi; Lei, Qi; Hu, Ming-Ming; Feng, Jun; Shu, Hong-Bing; Liu, Yi; Zhang, Xian-Zheng

    2016-12-01

    Hydrogen peroxide (H2O2) detection in biological systems is of significant importance, which act as critical second messenger in fundamental biological processes. Here, we report on a chemoselective fluorescent naphthylimide peroxide probe (NPP) for the H2O2 detection in vitro and in vivo. NPP is a phenylboronic acid-caged chromophore that selectively responds to H2O2 through a self-immolate mechanism. NPP exhibited high sensitivity and selectivity to H2O2 with distinctive fluorescence change due to the excellent two-photon excitation property, which permits the facile detection of inflammation produced H2O2 and offers chance to monitor the inflammatory stages in diseased cells.

  19. Hydrogen peroxide detection with high specificity in living cells and inflamed tissues.

    Science.gov (United States)

    Rong, Lei; Zhang, Chi; Lei, Qi; Hu, Ming-Ming; Feng, Jun; Shu, Hong-Bing; Liu, Yi; Zhang, Xian-Zheng

    2016-12-01

    Hydrogen peroxide (H2O2) detection in biological systems is of significant importance, which act as critical second messenger in fundamental biological processes. Here, we report on a chemoselective fluorescent naphthylimide peroxide probe (NPP) for the H2O2 detection in vitro and in vivo. NPP is a phenylboronic acid-caged chromophore that selectively responds to H2O2 through a self-immolate mechanism. NPP exhibited high sensitivity and selectivity to H2O2 with distinctive fluorescence change due to the excellent two-photon excitation property, which permits the facile detection of inflammation produced H2O2 and offers chance to monitor the inflammatory stages in diseased cells. PMID:27482463

  20. Hydrogen peroxide

    Science.gov (United States)

    The safety of fresh and fresh-cut produce available in salad-bar operations and supermarkets is a concern because of foodborne illness arising from consumption of fruits and vegetables that are surface contaminated with enteric pathogens. Field-packed produce are not generally washed because of the ...

  1. Trigonelline protects the cardiocyte from hydrogen peroxide induced apoptosis in H9c2 cells

    Institute of Scientific and Technical Information of China (English)

    Soundharrajan Ilavenil; Da Hye Kim; Young-Il Jeong; Mariadhas Valan Arasu; Mayakrishnan Vijayakumar; Ponnuraj Nagendra Prabhu; Srisesharam Srigopalram; Ki Choon Choi

    2015-01-01

    Objective: To elucidate the key parameters associated with hydrogen peroxide induced oxidative stress and investigates the mechanism of trigonelline (TG) for reducing the H2O2 induced toxicity in H9c2 cells. Methods: Cytotoxicity and antioxidant activity of TG was assessed by EZ-CYTOX kit. RNA extraction and cDNA synthesized according to the kit manufacture protocol. Apoptosis was measured by the Flowcytometry, general PCR and qPCR. Results: It was found that the TG significantly rescued the morphology of the H9c2 cells. Treatment of cells with TG attenuated H2O2 induced cell deaths and improved the antioxidant activity. In addition, TG regulated the apoptotic gene caspase-3, caspase-9 and anti-apoptotic gene Bcl-2, Bcl-XL during H2O2 induced oxidative stress in H9c2 cells. These results were comparable with quercetin treatment. For evident, flow cytometer results also confirmed the TG significantly reduced the H2O2 induced necrosis and apoptosis in H9c2 cells. However, further increment of TG concentration against H2O2 could induce the necrosis and apoptosis along with H2O2. Conclusions: It is suggested that less than 125 μM of TG could protect the cells from H2O2 induced cell damage by down regulating the caspases and up regulating the Bcl-2 and Bcl-XL expression. Therefore, we suggest the trigonelline could be useful for treatment of oxidative stress mediated cardiovascular diseases in future.

  2. A respiratory chain controlled signal transduction cascade in the mitochondrial intermembrane space mediates hydrogen peroxide signaling.

    Science.gov (United States)

    Patterson, Heide Christine; Gerbeth, Carolin; Thiru, Prathapan; Vögtle, Nora F; Knoll, Marko; Shahsafaei, Aliakbar; Samocha, Kaitlin E; Huang, Cher X; Harden, Mark Michael; Song, Rui; Chen, Cynthia; Kao, Jennifer; Shi, Jiahai; Salmon, Wendy; Shaul, Yoav D; Stokes, Matthew P; Silva, Jeffrey C; Bell, George W; MacArthur, Daniel G; Ruland, Jürgen; Meisinger, Chris; Lodish, Harvey F

    2015-10-20

    Reactive oxygen species (ROS) such as hydrogen peroxide (H2O2) govern cellular homeostasis by inducing signaling. H2O2 modulates the activity of phosphatases and many other signaling molecules through oxidation of critical cysteine residues, which led to the notion that initiation of ROS signaling is broad and nonspecific, and thus fundamentally distinct from other signaling pathways. Here, we report that H2O2 signaling bears hallmarks of a regular signal transduction cascade. It is controlled by hierarchical signaling events resulting in a focused response as the results place the mitochondrial respiratory chain upstream of tyrosine-protein kinase Lyn, Lyn upstream of tyrosine-protein kinase SYK (Syk), and Syk upstream of numerous targets involved in signaling, transcription, translation, metabolism, and cell cycle regulation. The active mediators of H2O2 signaling colocalize as H2O2 induces mitochondria-associated Lyn and Syk phosphorylation, and a pool of Lyn and Syk reside in the mitochondrial intermembrane space. Finally, the same intermediaries control the signaling response in tissues and species responsive to H2O2 as the respiratory chain, Lyn, and Syk were similarly required for H2O2 signaling in mouse B cells, fibroblasts, and chicken DT40 B cells. Consistent with a broad role, the Syk pathway is coexpressed across tissues, is of early metazoan origin, and displays evidence of evolutionary constraint in the human. These results suggest that H2O2 signaling is under control of a signal transduction pathway that links the respiratory chain to the mitochondrial intermembrane space-localized, ubiquitous, and ancient Syk pathway in hematopoietic and nonhematopoietic cells.

  3. 正己烷处理对菜蛾盘绒茧蜂滞育预蛹过氧化氢及抗氧化酶的影响%Effects of N-hexane on Hydrogen Peroxide Content and Activities of Three Antioxidant Enzymes in Diapausing Cotesia vestalis (Haliday) (Hymenoptera:Braconidae) Prepupae

    Institute of Scientific and Technical Information of China (English)

    侯佳秀; 徐登兰; 贺宜鹏; 陈超; 施祖华

    2014-01-01

    在27~29℃温度下,用1.5 mL/L的正己烷蒸气处理菜蛾盘绒茧蜂滞育蛹10~15 min后可以解除其滞育。为探讨解除滞育的机制,测定了正己烷处理后菜蛾盘绒茧蜂滞育预蛹体内的过氧化氢含量(H2O2)和3种抗氧化酶(SOD、POD和CAT)活性。结果表明正己烷处理后,滞育预蛹体内H2O2含量、SOD和POD活性均迅速上升,CAT活性则下降。就5个取样点的平均值而言,H2O2含量和SOD活性显著高于非滞育预蛹和未经处理的滞育预蛹,POD活性低于非滞育预蛹而高于未经处理的滞育预蛹,CAT活性则低于未经处理的滞育预蛹而高于非滞育预蛹。3种抗氧化酶活性的变化与体内H2O2含量的平衡有关,而H2O2含量的变化可能与体内激素水平的调节有关。%Exposure of the diapause individuals to 27-29 ℃ and 1.5 mL/L n-hexane for 10-15 min can effectively terminate diapause in Cotesia vestalis (Haliday). To unravel the mechanism of diapause termination, hydrogen peroxide content and activities of three antioxidant enzymes, superoxide dismutase (SOD), peroxidase (POD) and catalase (CAT), were quantified in diapause prepupae of C. vestalis. Results showed that, in the n-hexane-exposed diapause individuals, hydrogen peroxide content and activities of SOD and POD increased sharply, while activity of CAT declined. On average, hydrogen peroxide content and SOD activity were significantly higher in the exposed diapause prepupae than those in unexposed both diapause and non-diapause prepupae;POD activity was significantly lower than that in non-diapause prepupae but significantly higher than that in unexposed diapause prepupae; CAT activity was significantly lower than that in the unexposed diapause prepupae but significantly higher than that in non-diapause prepupae. Hydrogen peroxide content depends on activities of the three antioxidant enzymes, while the former can regulate hormone level in diapause prepupae, which may

  4. Composition and Properties of Hydrogen Peroxide Decomposing Systems in Extracellular and Total Extracts from Needles of Norway Spruce (Picea abies L., Karst.)

    OpenAIRE

    Polle, A.; Chakrabarti, K.; Schurmann, W.; Renneberg, H.

    1990-01-01

    Hydrogen peroxide (H2O2) scavenging systems of spruce (Picea abies) needles were investigated in both extracts obtained from the extracellular space and extracts of total needles. As assessed by the lack of activity of symplastic marker enzymes, the extracellular washing fluid was free from intracellular contaminations. In the extracellular washing fluid ascorbate, glutathione, cysteine, and high specific activities of guaiacol peroxidases were observed. Guaiacol peroxidases in the extracellu...

  5. Evaluation of the permeability of modified cellulose acetate propionate membranes for use in biosensors based on hydrogen peroxide detection

    OpenAIRE

    Guiomar, A. Jorge; Stephen D. Evans; Guthrie, James

    2001-01-01

    Phase inversion cellulose acetate propionate membranes showed lowpermeability to hydrogen peroxide aqueous solutions. Their permeability wasincreased by alkaline hydrolysis of the ester linking units. However, thepermeability remained lower than that of an unsubstituted cellulose membrane.The inclusion of hydroxypropyl cellulose in the membrane formulation, followedby an alkaline hydrolysis step, increased permeability to hydrogen peroxideaqueous solutions to 29% of that of an unsubstituted c...

  6. On-site applicability of hydrogen peroxide producing microbial electrochemical cells (MECs) coupled with UV in wastewater disinfection study

    Science.gov (United States)

    Background: There is an increased interest in the application of microbial electrochemical cell (MEC) for the recovery of value-added products such as hydrogen gas and hydrogen peroxide (H2O2) from wastewater. H2O2 has strong oxidation capability and produces hydroxyl radicals wh...

  7. ON-SITE APPLICABILITY OF HYDROGEN PEROXIDE PRODUCING MICROBIAL ELECTROCHEMICAL CELLS COUPLED WITH UV IN WASTEWATER DISINFECTION STUDY

    Science.gov (United States)

    There is an increased interest in the application of microbial electrochemical cell (MEC) for the recovery of value-added products such as hydrogen gas and hydrogen peroxide (H2O2) from wastewater. H2O2 has strong oxidation capability and produces hydroxyl radicals when coupled w...

  8. Synthesis of single-crystal α-MnO2 nanotubes-loaded Ag@C core-shell matrix and their application for electrochemical sensing of nonenzymatic hydrogen peroxide.

    Science.gov (United States)

    Zhang, Sai; Zheng, Jianbin

    2016-10-01

    A nonenzymatic hydrogen peroxide sensor was fabricated by combing the crystal α-MnO2 nanotubes and Ag@C core-shell matrix with their own superior characteristics. The morphology, size and electrochemical of the sensing interface materials and the relationship between the electrical catalytic properties and sensor response performance were also studied, established a new method for the detection of hydrogen peroxide (H2O2). The structure and morphology of hollow tubular-like MnO2 and MnO2-Ag@C film were characterized by scanning electron micrograph (SEM), transmission electron microscopy (TEM) and X-ray diffraction. The electrochemical properties of the sensor were explored by cyclic voltammetry and amperometry. The investigation showed that the MnO2-Ag@C at the sensor exhibited a high electrocatalytic activity towards electroreduction of hydrogen peroxide; and under the optimal conditions, the linear ranges of hydrogen peroxide were 0.5μM to 5.7mM with a low detection limit of 0.17μM (S/N=3) and high sensitivity of 127.2μAmM(-1)cm(-2). Compared with other nonenzymatic hydrogen peroxide sensor, the fabricated sensor own lower detection limit, demonstrating that MnO2-Ag@C nanocomposite film will be a new promising platform for the construction of hydrogen peroxide sensors. PMID:27474303

  9. Induction of eosinophil apoptosis by hydrogen peroxide promotes the resolution of allergic inflammation.

    Science.gov (United States)

    Reis, A C; Alessandri, A L; Athayde, R M; Perez, D A; Vago, J P; Ávila, T V; Ferreira, T P T; de Arantes, A C S; Coutinho, D de Sá; Rachid, M A; Sousa, L P; Martins, M A; Menezes, G B; Rossi, A G; Teixeira, M M; Pinho, V

    2015-01-01

    Eosinophils are effector cells that have an important role in the pathogenesis of allergic disease. Defective removal of these cells likely leads to chronic inflammatory diseases such as asthma. Thus, there is great interest in understanding the mechanisms responsible for the elimination of eosinophils from inflammatory sites. Previous studies have demonstrated a role for certain mediators and molecular pathways responsible for the survival and death of leukocytes at sites of inflammation. Reactive oxygen species have been described as proinflammatory mediators but their role in the resolution phase of inflammation is poorly understood. The aim of this study was to investigate the effect of reactive oxygen species in the resolution of allergic inflammatory responses. An eosinophilic cell line (Eol-1) was treated with hydrogen peroxide and apoptosis was measured. Allergic inflammation was induced in ovalbumin sensitized and challenged mouse models and reactive oxygen species were administered at the peak of inflammatory cell infiltrate. Inflammatory cell numbers, cytokine and chemokine levels, mucus production, inflammatory cell apoptosis and peribronchiolar matrix deposition was quantified in the lungs. Resistance and elastance were measured at baseline and after aerosolized methacholine. Hydrogen peroxide accelerates resolution of airway inflammation by induction of caspase-dependent apoptosis of eosinophils and decrease remodeling, mucus deposition, inflammatory cytokine production and airway hyperreactivity. Moreover, the inhibition of reactive oxygen species production by apocynin or in gp91(phox-/-) mice prolonged the inflammatory response. Hydrogen peroxide induces Eol-1 apoptosis in vitro and enhances the resolution of inflammation and improves lung function in vivo by inducing caspase-dependent apoptosis of eosinophils. PMID:25675292

  10. Hydrogen Peroxide Induced Changes in Energy Status and Respiration Metabolism of Harvested Longan Fruit in Relation to Pericarp Browning.

    Science.gov (United States)

    Lin, Yi-Xiong; Lin, Yi-Fen; Chen, Yi-Hui; Wang, Hui; Shi, John; Lin, He-Tong

    2016-06-01

    Energy status and respiration metabolism of "Fuyan" longan fruit treated by hydrogen peroxide (H2O2) and their relationship to pericarp browning were studied. The results displayed that H2O2 significantly increased the respiration rate, increased activities of respiratory terminal oxidases like cytochrome C oxidase (CCO) and ascorbic acid oxidase (AAO), decreased NAD kinase activity, maintained lower contents of NADP and NADPH as well as higher amounts of NAD and NADH, and accelerated the decrease of energy charge. These results gave convincing evidence that the treatment of H2O2 for accelerating longan pericarp browning was due to an increase of energy deficiency, an increase of respiratory metabolic pathways of Embden-Meyerhof pathway (EMP) and tricarboxylic acid (TCA) cycle, a decrease of pentose phosphate pathway (PPP) of respiratory pathway, and an increase of activities of respiratory terminal oxidases like CCO and AAO. PMID:27213701

  11. Sliding discharges in steam: effects of dielectric surface and hydrocarbon additives on hydrogen, oxygen and hydrogen peroxide generation

    International Nuclear Information System (INIS)

    A sliding surface discharge was formed on a dielectric layer in steam at ∼100 °C and atmospheric pressure. The material properties and the thickness of the dielectric layer were found to strongly affect the energy deposition into the plasma. With a 0.32 cm thick dielectric the energy deposition was 1.4 times greater than with a 0.48 cm thick dielectric, and with window glass it was 1.3 times greater than with Macor of the same thickness. Product gases were H2 (73 ± 4%) and O2 (27 ± 1%), and H2O2 accumulated in the condensed water up to 0.4 g l−1. The energy yield for hydrogen was 1.2 ± 0.1 g H2 kWh−1 and independent of the input power and thickness or material of the dielectric. However, for hydrogen peroxide the energy yield, which varied between 0.61 and 3.2 g H2O2 kWh−1, was found to depend strongly on the thickness and material of the dielectric. The addition of benzene to the steam increased the energy efficiency of hydrogen to 2.3 g kWh−1, and decreased oxygen and hydrogen peroxide by about 3 and 6 times, respectively. It also caused the deposition of phenol and polymer-like layers on the dielectric. The results are explained on the basis of reactions of H and OH radicals adsorbed on the surface and/or in gas phase. (paper)

  12. Screen-printable silver nanoparticulate-based inks for the electrocatalysis of hydrogen peroxide

    OpenAIRE

    Goodison, Alan; Killard, Anthony J.; Morrin, Aoife

    2013-01-01

    The detection of hydrogen peroxide has been shown to be very important in recent years due to its relevant role in many industrial applications as well as biological reactions. We are interested in it as a quantitative marker for oxidase-based biosensor applications where it is produced when substrate (e.g., glucose, cholesterol) is catalysed by its respective oxidase enzyme. Previously, a commercial silver flake-based screen-printing ink (PF-410, Acheson®), when treated with surfactant and s...

  13. A rare case of portal vein gas: accidental hydrogen peroxide ingestion

    OpenAIRE

    Zengin, Suat; Al, Behcet; Genç, Sinan; Yarbil, Pınar; Yilmaz, Demet Ari; Gulsen, Murat Taner

    2012-01-01

    Hydrogen peroxide (H2O2) is a colourless and odourless liquid with oxidant characteristics used for various purposes. Whereas in lower concentrations (3%), H2O2 is used as a disinfectant in home cleaning products and wound care, in higher concentrations (35%) it is used in textile and paper industry as a bleaching agent and is diluted for use in lightening hair dyes. Like other caustic substances, direct injuries may develop if H2O2 is swallowed and systemic air embolisms may occur due to the...

  14. Visualization of Endogenous and Exogenous Hydrogen Peroxide Using A Lysosome-Targetable Fluorescent Probe

    Science.gov (United States)

    Kim, Dabin; Kim, Gyoungmi; Nam, Sang-Jip; Yin, Jun; Yoon, Juyoung

    2015-02-01

    Reactive oxygen species (ROS) play crucial roles in diverse physiological processes; therefore, the efficient detection of ROS is very crucial. In this study, we report a boronate-based hydrogen peroxide (H2O2) probe having naphthalimide fluorophore. This probe also contained a morpholine moiety as a directing group for lysosome. The recognition property indicated that the probe exhibited high selectivity towards H2O2 not only in the solution but also in the living cells. Furthermore, it was used to monitor the level of endogenous and exogenous H2O2. These results support that the probe can function as an efficient indicator to detect H2O2.

  15. The E-loop Is Involved in Hydrogen Peroxide Formation by the NADPH Oxidase Nox4*

    OpenAIRE

    Takac, Ina; Schröder, Katrin; Zhang, Leilei; Lardy, Bernard; Anilkumar, Narayana; Lambeth, J. David; Shah, Ajay M.; Morel, Francoise; Brandes, Ralf P.

    2011-01-01

    In contrast to the NADPH oxidases Nox1 and Nox2, which generate superoxide (O2˙̄), Nox4 produces hydrogen peroxide (H2O2). We constructed chimeric proteins and mutants to address the protein region that specifies which reactive oxygen species is produced. Reactive oxygen species were measured with luminol/horseradish peroxidase and Amplex Red for H2O2 versus L-012 and cytochrome c for O2˙̄. The third extracytosolic loop (E-loop) of Nox4 is 28 amino acids longer than that of Nox1 or Nox2. Dele...

  16. Inactivation of possible microorganism food contaminants on packaging foils using nonthermal plasma and hydrogen peroxide

    Science.gov (United States)

    Scholtz, V.; Khun, J.; Soušková, H.; Čeřovský, M.

    2015-07-01

    The inactivation effect of nonthermal plasma generated in electric discharge burning in air atmosphere with water or hydrogen peroxide aerosol for the application to the microbial decontamination of packaging foils is studied. The microbial inactivation is studied on two bacterial, two yeasts, and two filamentous micromycete species. The inactivation of all contaminating microorganisms becomes on the area of full 8.5 cm in diameter circular sample after short times of several tens of seconds. Described apparatus may present a possible alternative method of microbial decontamination of food packaging material or other thermolabile materials.

  17. Degradation of 2,4-dichlorophenoxyacetic acid in water by ozone-hydrogen peroxide process

    Institute of Scientific and Technical Information of China (English)

    YU Ying-hui; MA Jun; HOU Yan-jun

    2006-01-01

    This study reports an investigation into the degradation of 2,4-dichlorophenoxyacetic acid in bubble contactor column by O3/H2O2 process, which is widely used as a principal advanced oxidation process. The degradation of 2,4-dichlorophenoxyacetic acid was studied under different H2O2/O3 molar ratio and pH value. Meanwhile, TOC removal was investigated both in distilled water and tap water. The influences of ozone transfer and consumed hydrogen peroxide were also discussed. The degradation products and oxidation intermediates were identified by GC-MS and LC-MS. A possible reaction mechanism was thus proposed.

  18. Low-dose hydrogen peroxide application in closed recirculating aquaculture systems

    DEFF Research Database (Denmark)

    Pedersen, Lars-Flemming; Good, C.; Pedersen, Per Bovbjerg

    2012-01-01

    The aim of the present work was to simulate water treatment practices with hydrogen peroxide (HP) in recirculating aquaculture systems (RAS). Six identical 1,700-L pilot-scale RAS were divided into two experimental groups based on daily feed allocation and operated under constant conditions...... and contradict prevailing notions that HP cannot be used safely in RAS that employ biofiltration. The development of effective new HP treatment protocols for recirculating aquaculture could reduce the current dependence on formalin to improve water quality and control parasitic loads...

  19. Low doses of ionizing radiation and hydrogen peroxide stimulate plant growth

    International Nuclear Information System (INIS)

    The present study shows that low-dose oxidative stress induced by ionizing radiation (10-20 cGy) and hydrogen peroxide (1-100 pmol per litre) stimulates germination of seeds and growth of sprouts and roots. The growth of seedlings can be stimulated by treatment of seeds as well as seedlings but in the latter case it needs lower doses. The stimulation effect is observed in a narrow dose interval which is the same for the plant species studied: barley, wheat, pea, maize and melon

  20. Photocatalytic Degradation of Pesticides in Natural Water: Effect of Hydrogen Peroxide

    OpenAIRE

    Natividad Miguel; Ormad, María P.; Rosa Mosteo; José L. Ovelleiro

    2012-01-01

    The aim of this paper is to evaluate the effectiveness of photocatalytic treatment with titanium dioxide in the degradation of 44 organic pesticides analyzed systematically in the Ebro river basin (Spain). The effect of the addition of hydrogen peroxide in this treatment is studied, and a monitoring of effectiveness of photocatalytic processes is carried out by measurements of physical-chemical parameters of water. The application of photocatalytic treatment with 1 g L−1 of TiO2 during 30 min...

  1. Environmentally Benign Oxidation of Some Organic Sulfides with 34% Hydrogen Peroxide Catalyzed by Simple Heteropolyoxometalates

    Institute of Scientific and Technical Information of China (English)

    TAYEBEE,Reza; ALIZADEH,Moharnmad Hassan

    2007-01-01

    An environmentally benign oxygenation protocol was developed for selective oxidation of some types of aromatic and aliphatic sulfides in good to excellent yields utilizing 34% hydrogen peroxide catalyzed by simple heteropolyoxometalates in normal drinking water at room temperature. The catalysts could be recovered and reused for at least seven reaction cycles under the described reaction conditions without considerable loss of reactivity. This procedure introduced a new insight into the use of simple heteropolyanions as recoverable catalysts for the oxidation of organic sulfides by an environmentally acceptable protocol.

  2. ExoMol line lists XV: A new hot line list for hydrogen peroxide

    OpenAIRE

    Al-Refaie, Ahmed F.; Polyansky, Oleg L.; Ovsyannikov, Roman I.; Tennyson, Jonathan; Yurchenko, Sergei N.

    2016-01-01

    A computed line list for hydrogen peroxide, H$_2{}^{16}$O$_2$, applicable to temperatures up to $T=1250$~K is presented. A semi-empirical high accuracy potential energy surface is constructed and used with an {\\it ab initio} dipole moment surface as input TROVE to compute 7.5 million rotational-vibrational states and around 20 billion transitions with associated Einstein-$A$ coefficients for rotational excitations up to $J=85$. The resulting APTY line list is complete for wavenumbers below 6~...

  3. Hydrogen peroxide is involved in cGMP modulating the lateral root development of Arabidopsis thaliana

    OpenAIRE

    Li, Jisjeng; Jia, Honglei

    2013-01-01

    3′,5′-cyclic guanosine monophosphate (cGMP) and hydrogen peroxide (H2O2) function as the important signaling molecule which promote the lateral root development of Arabidopsis thaliana. In this study, interestingly, application of 8-Br-cGMP (the membrane permeable cGMP analog) promoted the endogenous H2O2 production. In addition, the decrease of endogenous H2O2 also inhibited the effect of cGMP on the lateral root development. Thus, H2O2 maybe act as a downstream signaling of cGMP molecule wh...

  4. Antimicrobial mechanisms behind photodynamic effect in the presence of hydrogen peroxide

    OpenAIRE

    Garcez, Aguinaldo Silva; Núñez, Silvia Cristina; Baptista, Mauricio S.; Daghastanli, Nasser Ali; Itri, Rosangela; Hamblin, Michael R.; Ribeiro, Martha Simões

    2010-01-01

    This study describes the use of methylene blue (MB) plus light (photodynamic inactivation, PDI) in the presence of hydrogen peroxide (H2O2) to kill Staphylococcus aureus, Escherichia coli, and Candida albicans. When H2O2 was added to MB plus light there was an increased antimicrobial effect, which could be due to a change in the type of ROS generated or increased microbial uptake of MB. To clarify the mechanism, the production of ROS was investigated in the presence and absence of H2O2. It wa...

  5. A passive apparatus for controlled-flux delivery of biocides: hydrogen peroxide as an example

    DEFF Research Database (Denmark)

    Olsen, Stefan Møller; Pedersen, L.T.; Dam-Johansen, Kim;

    2010-01-01

    A new test method has been developed to estimate the required release rate of hydrogen peroxide (H2O2) to prevent marine biofouling. The technique exploits a well-defined concentration gradient of biocide across a cellulose acetate membrane. A controlled flux of H2O2, an environmentally friendly...... of approximately 2800 mu g cm(-2) day(-1) deterred biofouling efficiently. A H2O2 release rate of about 224 mu g cm(-2) day(-1) resulted in some slime formation, but it was less than that on the H2O2-free control. It appears that to obtain efficient resistance to biofouling in natural seawater requires much higher...

  6. Inactivation of possible microorganism food contaminants on packaging foils using nonthermal plasma and hydrogen peroxide

    International Nuclear Information System (INIS)

    The inactivation effect of nonthermal plasma generated in electric discharge burning in air atmosphere with water or hydrogen peroxide aerosol for the application to the microbial decontamination of packaging foils is studied. The microbial inactivation is studied on two bacterial, two yeasts, and two filamentous micromycete species. The inactivation of all contaminating microorganisms becomes on the area of full 8.5 cm in diameter circular sample after short times of several tens of seconds. Described apparatus may present a possible alternative method of microbial decontamination of food packaging material or other thermolabile materials

  7. Microbicidal efficacy of an advanced oxidation process using ozone/hydrogen peroxide in water treatment.

    Science.gov (United States)

    Sommer, R; Pribil, W; Pfleger, S; Haider, T; Werderitsch, M; Gehringer, P

    2004-01-01

    The combined application of ozone and hydrogen peroxide represents a kind of advanced oxidation for water treatment. The radicals that are generated during the process are used for the degradation of organic pollutants from groundwater and industrial effluents. The aim of our study was to evaluate the possible microbicidal, and particularly virucidal, efficacy of such a process, since no substantial data were available. The investigations were performed at a pilot plant installed for the elimination of perchloroethylene from polluted groundwater (reduction efficacy for perchloroethylene from 26 microg/L to 5 microg/L). To enable a reliable evaluation of the microbicidal effect, a set of alternate test organisms was used. As model viruses we chose bacteriophages MS2 (F+ specific, single-stranded RNA), phiX174 (single-stranded DNA) and PRD-1 (coated, double-stranded DNA). Furthermore, spores of Bacillus subtilis were included as possible surrogates for protozoa and Escherichia coli as representative for traditional indicator bacteria used in water analysis. The microbicidal efficiency was compared to the inactivation by means of ozone under two standard conditions (20 degrees C): (a) 0.4 mg/L residual after 4 min and (b) 0.1 mg/L residual after 10 min. Surprisingly, a good microbicidal effect of the ozone/hydrogen peroxide process was found. This was somewhat unexpected, because we had assumed that the disinfection potential of ozone would have been interfered with by the presence of hydrogen peroxide. Escherichia coli and the three test viruses revealed a reduction of about 6-log. In contrast, spores of Bacillus subtilis showed after the total process a reduction of 0.4-log. These results matched the effect of the ozone treatment (a) with a residual of 0.4 mg/L after 4 min contact time (20 degrees C). The test condition (b) with a residual of 0.1 mg/L ozone after a contact time of 10 min at 20 degrees C gave a higher reduction of the B. subtilis spores (1.5-log

  8. Electrochemically Reduced Graphene Oxide-nafion/Au Nanoparticle Modified Electrode for Hydrogen Peroxide Sensing

    OpenAIRE

    Yajie Lv; Fang Wang; Hui Zhu; Xiaorong Zou; Cheng-an Tao; Jianfang Wang

    2016-01-01

    n this paper, a non-enzymatic hydrogen peroxide (H2O2) sensor, based on Au nanoparticles (AuNPs) electrodepos‐ ited on an electrochemically reduced graphene oxide(ER‐ GO)-Nafion modified glass carbon electrode (GCE), was reported. The graphene oxide-(GO-)Nafion nanocompo‐ sites were first assembled on the GCE surface to produce a GO-Nafion electrode. GO was then electrochemically reduced to produce an ERGO-Nafion modified GCE (to be subsequently denoted as GCE/ERGO-Nafion). Afterwards, AuNPs ...

  9. Inactivation of possible microorganism food contaminants on packaging foils using nonthermal plasma and hydrogen peroxide

    Energy Technology Data Exchange (ETDEWEB)

    Scholtz, V., E-mail: Vladimir.Scholtz@vscht.cz; Khun, J. [Institute of Chemical Technology in Prague, Department of Physics and Measurements, Faculty of Chemical Engineering (Czech Republic); Soušková, H. [Institute of Chemical Technology in Prague, Department of Computing and Control Engineering, Faculty of Chemical Engineering (Czech Republic); Čeřovský, M. [Institute of Chemical Technology in Prague, Department of Food Preservation, Faculty of Food and Biochemical Technology (Czech Republic)

    2015-07-15

    The inactivation effect of nonthermal plasma generated in electric discharge burning in air atmosphere with water or hydrogen peroxide aerosol for the application to the microbial decontamination of packaging foils is studied. The microbial inactivation is studied on two bacterial, two yeasts, and two filamentous micromycete species. The inactivation of all contaminating microorganisms becomes on the area of full 8.5 cm in diameter circular sample after short times of several tens of seconds. Described apparatus may present a possible alternative method of microbial decontamination of food packaging material or other thermolabile materials.

  10. Treated domestic sewage: kinetics of Escherichia coli and total coliform inactivation by oxidation with hydrogen peroxide

    Directory of Open Access Journals (Sweden)

    Gean Delise L. P. Vargas

    2013-01-01

    Full Text Available Hydrogen peroxide has been used for decades in developed countries as an oxidizing agent in the treatment of water, domestic sewage and industrial effluents. This study evaluated the influence of the concentration of H2O2 and pH on the inactivation of Escherichia coli cells and the disinfection of sewage treated. The results showed that the inactivation rate increased with pH and H2O2. The presence of other contaminants dissolved in the effluent is probably the cause of these differences, because E. coli inactivation in synthetic wastewater was found to be much faster than in the real treated domestic sewage.

  11. Mitochondria-derived hydrogen peroxide selectively enhances T cell receptor-initiated signal transduction.

    Science.gov (United States)

    Gill, Tejpal; Levine, Alan D

    2013-09-01

    T cell receptor (TCR)-initiated signal transduction is reported to increase production of intracellular reactive oxygen species, such as superoxide (O2˙(-)) and hydrogen peroxide (H2O2), as second messengers. Although H2O2 can modulate signal transduction by inactivating protein phosphatases, the mechanism and the subcellular localization of intracellular H2O2 as a second messenger of the TCR are not known. The antioxidant enzyme superoxide dismutase (SOD) catalyzes the dismutation of highly reactive O2˙(-) into H2O2 and thus acts as an intracellular generator of H2O2. As charged O2˙(-) is unable to diffuse through intracellular membranes, cells express distinct SOD isoforms in the cytosol (Cu,Zn-SOD) and mitochondria (Mn-SOD), where they locally scavenge O2˙(-) leading to production of H2O2. A 2-fold organelle-specific overexpression of either SOD in Jurkat T cell lines increases intracellular production of H2O2 but does not alter the levels of intracellular H2O2 scavenging enzymes such as catalase, membrane-bound peroxiredoxin1 (Prx1), and cytosolic Prx2. We report that overexpression of Mn-SOD enhances tyrosine phosphorylation of TCR-associated membrane proximal signal transduction molecules Lck, LAT, ZAP70, PLCγ1, and SLP76 within 1 min of TCR cross-linking. This increase in mitochondrial H2O2 specifically modulates MAPK signaling through the JNK/cJun pathway, whereas overexpressing Cu,Zn-SOD had no effect on any of these TCR-mediated signaling molecules. As mitochondria translocate to the immunological synapse during TCR activation, we hypothesize this translocation provides the effective concentration of H2O2 required to selectively modulate downstream signal transduction pathways.

  12. Preparation of zirconia coatings by hydrolysis of zirconium alkoxide with hydrogen peroxide

    International Nuclear Information System (INIS)

    Zirconia has gained a great deal of attention because of its superior properties of mechanical strength, chemical resistance, and ionic conductivity. Zirconia coatings and thin films are receiving attention as tribological and thermal barrier coatings for engines, high-reflective coatings, solid electrolytes for fuel cells, oxygen sensors, etc. The sol-gel coating method has several advantages, such as low processing temperatures, homogeneity, control of micro-structure, and good productivity compared to chemical vapor deposition and physical vapor deposition. However, there are few reports concerning the preparation of zirconia coatings and thin films by the sol-gel method. Up to the present, zirconia coatings have been prepared from zirconium propoxide (not heated), zirconium tetrabutoxide modified by acetylacetone and ethyl acetoacetate, zirconium diethoxydichloride (ZrCl2(OC2H5)2), and a hydrosol prepared from a zirconium oxychloride solution. Coatings of 8.8-mol%-yttria-doped zirconia were fabricated using a transparent and spinnable sol prepared by hydrolysis of zirconium alkoxide with hydrogen peroxide and nitric acid. The sol gave a crack-free coating film consisting of fine grains. The crystalline phase was cubic after heating of 1,000 and 1,200 C and cubic and tetragonal at 1,350 C, with the coating being highly oriented in the (111) plane, especially at 1,000 C. Activation energy of the coating films was higher than that of the bulk. Transmittance through a film thickness of about 0.3 μm on each side was 75%

  13. Synergistic inactivation of anaerobic wastewater biofilm by free nitrous acid and hydrogen peroxide

    International Nuclear Information System (INIS)

    Highlights: ► H2O2 greatly enhances the inactivation of microorganisms in biofilms by FNA. ► About 2-log of inactivation of biofilm microbes was achieved by FNA + H2O2. ► FNA + H2O2 reduced sulfide production and detached biofilm in reactors. -- Abstract: Free nitrous acid (FNA) was recently revealed to be a strong biocide for microbes in anaerobic biofilm, achieving approximately 1-log (90%) inactivation at a concentration of 0.2–0.3 mgHNO2-N/L with an exposure time longer than 6 h. The combined biocidal effects of FNA and hydrogen peroxide (H2O2) on anaerobic wastewater biofilm are investigated in this study. H2O2 greatly enhances the inactivation of microorganisms by FNA. About 2-log (99%) of microbial inactivation was achieved when biofilms were exposed to FNA at 0.2 mgN/L or above and H2O2 at 30 mg/L or above for 6 h or longer. It was found, through response surface methodology and ridge analysis, that FNA is the primary inactivation agent and H2O2 enhances its efficiency. The loss and the subsequent slow recovery of biological activity in biofilm reactors subjected to FNA and H2O2 dosing confirmed that the chemical combination could achieve higher microbial inactivation than with FNA alone. Reaction simulation shows that intermediates of reactions between FNA and H2O2, like peroxynitrite and nitrogen dioxide, would be produced at elevated levels and are likely responsible for the synergism between FNA and H2O2. The combination of FNA and H2O2 could potentially provide an effective solution to sewer biofilm control

  14. Leaching performance of imidazolium based ionic liquids in the presence of hydrogen peroxide for recovery of metals from brass waste

    OpenAIRE

    Kilicarslan, Ayfer; Saridede, Muhlis N.

    2016-01-01

    The application of ionic liquids (ILs), 1-methylimidazolium hydrogen sulfate (HmimHSO4), 1-ethyl-3-methylimidazolium hydrogen sulfate (HmimHSO4) and 1-butyl-3-methylimidazolium chloride (BmimCl) as leaching agents was investigated in the leaching of copper and zinc from brass waste in the presence of an oxidant, hydrogen peroxide (H2O2). Factors that affect copper and zinc dissolution rates such as ionic liquid concentration, time and temperature were investigated. The results indicated that ...

  15. Release of hydrogen peroxide and antioxidant by the coral Stylophora pistillata to its external milieu

    Science.gov (United States)

    Armoza-Zvuloni, R.; Shaked, Y.

    2014-01-01

    Hydrogen peroxide (H2O2), a common reactive oxygen species, plays multiple roles in coral health and disease. Elevated H2O2 production by the symbiotic algae during stress may result in symbiosis breakdown and bleaching of the coral. We have recently reported that various Red Sea corals release H2O2 and antioxidants to their external milieu and can influence the H2O2 dynamics in the reef. Here we present laboratory characterization of H2O2 and antioxidant activity release kinetics by intact, non-stressed Stylophora pistillata. Experimenting with bleached and non-bleached corals and different stirring speeds, we explored the sources and modes of H2O2 and antioxidant release. Since H2O2 is produced and degraded simultaneously, we developed methodology for resolving the actual rates of H2O2 release by the corals. H2O2 and antioxidant activity linearly increased in the water surrounding the coral over short periods of 1-2 h. Over longer periods of 5-7 h, the antioxidant activity kept increasing with time, while H2O2 concentrations were stabilized at ~ 1 μM by 2-3 h, and then gradually declined. Solving for H2O2 release, corals were found to release H2O2 at increasing rates over 2-4 h, and then slow down and stop by 5-7 h. Stirring was shown to induce the release of both H2O2 and antioxidant activity, possibly due to ventilation of the coral by the flow. Antioxidant activity was released at similar rates by bleached and non-bleached corals, suggesting that the antioxidant did not originate from the symbiotic algae. H2O2, however, was only minimally released from bleached corals, implying that the symbiotic algae are the source of the released H2O2. The observed flow-induced H2O2 release may aid corals in removing some of the internal H2O2 produced by their symbiotic algae and possibly assist in preventing coral bleaching under conditions of elevated temperature and irradiance.

  16. Facile synthesis of silver nanostructures by using various deposition potential and time: A nonenzymetic sensor for hydrogen peroxide

    Energy Technology Data Exchange (ETDEWEB)

    Amiri, Mandana, E-mail: mandanaamiri@uma.ac.ir [Department of Chemistry, University of Mohaghegh Ardabili, Ardabil (Iran, Islamic Republic of); Nouhi, Sima [Department of Chemistry, University of Mohaghegh Ardabili, Ardabil (Iran, Islamic Republic of); Azizian-Kalandaragh, Yashar [Department of Physics, University of Mohaghegh Ardabili, Ardabil (Iran, Islamic Republic of)

    2015-04-01

    Silver nanostructures have been successfully fabricated by using electrodeposition method onto indiumtinoxide (ITO) substrate. Scanning electron microscopy (SEM), electrochemical impedance spectroscopy (EIS) and ultraviolet–visible spectroscopy (UV–Vis) techniques were employed for characterization of silver nanostructures. The results show nanostructures with different morphology and electrochemical properties can be obtained by various deposition potentials and times. Electrochemical behavior of the nanostructures has been studied by using cyclic voltammetry. Silver nanostructures exhibits good electrocatalytic activity towards the reduction of H{sub 2}O{sub 2}. The presented electrode can be employed as sensing element for hydrogen peroxide. - Highlights: • Silver nanostructures (AgNS) have been fabricated using electrodeposition ITO. • AgNS with different morphology and electrochemical properties obtained. • AgNS exhibits good electrocatalytic activity for reduction of H{sub 2}O{sub 2}.

  17. Development of a handheld sensor system system for the online measurement of hydrogen peroxide in aseptic filling systems

    Energy Technology Data Exchange (ETDEWEB)

    Reisert, Steffen; Schoening, Michael J. [Institute of Nano- and Biotechnologies, Aachen University of Applied Sciences, Juelich (Germany); Henkel, Hartmut; Schneider, Andreas; Schaefer, Daniel [von Hoerner and Sulger GmbH, Schwetzingen (Germany); Friedrich, Peter [Aseptiksysteme and Foodtechnologie, Linnich (Germany); Berger, Joerg [Filldesign GmbH, Moenchengladbach (Germany)

    2010-04-15

    A handheld sensor system for the online measurement of hydrogen peroxide (H{sub 2}O{sub 2}) in aseptic sterilisation processes has been developed. It is based on a calorimetric-type gas sensor that consists of a differential set-up of two temperature sensors, of which one is catalytically activated and the second one is passivated and used as reference. The sensor principle relies in detecting a rise in temperature on the active sensor due to the exothermic reaction of H{sub 2}O{sub 2} on the catalytic surface. To characterise the sensor system towards H{sub 2}O{sub 2} sensitivity and other influencing factors, measurements have been carried out both at an experimental set-up and a manufacturer's sterilisation machine. Physical sensor characterisation was done by means of the optical microscopy. (Abstract Copyright [2010], Wiley Periodicals, Inc.)

  18. Kinetics of Oxidation of L-Leucine by Mono-and Bimetallic Gold and Silver Nanoparticles in Hydrogen Peroxide Solution

    Institute of Scientific and Technical Information of China (English)

    P.VENKATESAN; J.SANTHANALAKSHMI

    2012-01-01

    The catalytic activity of surfactant stabilized mono- and bimetallic Au and Ag nanoparticles for the oxidation of an amino acid,L-leucine,was studied using hydrogen peroxide as the oxidant.The Au and Ag nanoparticle catalysts exhibited very good catalytic activity and the kinetics of the reaction were found to be pseudo-first order with respect to the amino acid.The effects of several factors,such as oxidant concentration,ionic strength,pH,and catalyst concentration on the reaction,were also investigated.In particular,optimal oxidant and catalyst concentrations were determined.Very high concentrations of the metal nano-catalysts or the oxidant led to a dramatic increase in reaction rate.Moreover,bimetallic Au-Ag catalysts provided higher selectivity than pure Au or Ag.

  19. Micromorphology and microhardness of enamel after treatment with home-use bleaching agents containing 10% carbamide peroxide and 7.5% hydrogen peroxide

    Directory of Open Access Journals (Sweden)

    Robson Tetsuo Sasaki

    2009-12-01

    Full Text Available OBJECTIVE: The purpose of this study was to assess the effect of home-use bleaching agents containing 10% carbamide peroxide and 7.5% hydrogen peroxide on enamel microhardness and surface micromorphology. MATERIAL AND METHODS: Enamel slabs (n=10 received the bleaching agents for 1 h/day and remained in artificial saliva solution for 23 h/day, during a total period of 21 days. Control group was composed of enamel slabs that were not subjected to treatment with the agents and were maintained in artificial saliva solution. Microhardness tests were performed before treatment application, 21 days of treatment and 14 days after the end of treatment. Scanning electron microscopy analyses were performed after 14 days after the end of bleaching treatment by 3 calibrated observers who attributed scores. RESULTS: The Tukey's test (α=0.05 showed no significant differences in microhardness values among bleaching agents, at 21 days of treatment and a significant increase in microhardness for different agents after 14 days from the end of treatment. Fisher's exact test showed differences in micromorphology of enamel between control and experimental groups (p=0.0342. CONCLUSIONS: Bleaching agents containing 10% carbamide peroxide and 7.5% hydrogen peroxide may change surface micromorphology of enamel, although no changes in microhardness were observed.

  20. Dissolution of Uranium(IV) Oxide in Solutions of Ammonium Carbonate and Hydrogen Peroxide

    Energy Technology Data Exchange (ETDEWEB)

    Smith, Steven C.; Peper, Shane M.; Douglas, Matthew; Ziegelgruber, Kate L.; Finn, Erin C.

    2009-09-12

    Understanding the dissolution characteristics of uranium oxides is of fundamental scientific interest. Bench scale experiments were conducted to determine the optimal dissolution parameters of uranium(IV) oxide (UO2) powder in solutions of ammonium carbonate [(NH4)2CO3] and hydrogen peroxide (H2O2). Experimental parameters included variable peroxide and carbonate concentrations, and temperature. Results indicate the dissolution rate of UO2 in 1 M (NH4)2CO3 increases linearly with peroxide concentration ranging from 0.05 – 2 M (1:1 to 40:1 mol ratio H2O2:U), with no apparent maximum rate reached under the limited conditions used in our study. Temperature ranging studies show the dissolution rate of UO2 in 1 M (NH4)2CO3 and 0.1 M H2O2 (2:1 mol ratio H2O2:U) increases linearly from 15 °C to 60 °C, again with no apparent maximum rate reached. Dissolution of UO2 in solutions with constant [H2O2] and [(NH4)2CO3] ranging from 0.5 to 2 M showed no difference in rate; however dissolution was significantly reduced in 0.05 M (NH4)2CO3 solution. The results of this study demonstrate the influence of [H2O2], [(NH4)2CO3], and temperature on the dissolution of UO2 in peroxide-containing (NH4)2CO3 solutions. Future studies are planned to elucidate the solution and solid state complexes in these systems.