A novel nonenzymatic amperometric hydrogen peroxide sensor based on CuO@Cu2O nanowires embedded into poly(vinyl alcohol).

PubMed

Chirizzi, Daniela; Guascito, Maria Rachele; Filippo, Emanuela; Tepore, Antonio

2016-01-15

A new, very simple, rapid and inexpensive nonenzymatic amperometric sensor for hydrogen peroxide (H2O2) detection is proposed. It is based on the immobilization of cupric/cuprous oxide core shell nanowires (CuO@Cu2O-NWs) in a poly(vinyl alcohol) (PVA) matrix directly drop casted on a glassy carbon electrode surface to make a CuO@Cu2O core shell like NWs PVA embedded (CuO@Cu2O-NWs/PVA) sensor. CuO nanowires with mean diameters of 120-170nm and length in the range 2-5μm were grown by a simple catalyst-free thermal oxidation process based on resistive heating of pure copper wires at ambient conditions. The oxidation process of the copper wire surface led to the formation of a three layered structure: a thick Cu2O bottom layer, a CuO thin intermediate layer and CuO nanowires. CuO nanowires were carefully scratched from Cu2O layer with a sharp knife, dispersed into ethanol and sonicated. Then, the NWs were embedded in PVA matrix. The morphological and spectroscopic characterization of synthesized CuO-NWs and CuO@Cu2O-NWs/PVA were performed by transmission electron microscopy (TEM), selected area diffraction pattern (SAD), scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS) analysis. Moreover a complete electrochemical characterization of these new CuO@Cu2O-NWs/PVA modified glassy carbon electrodes was performed by Cyclic Voltammetry (CV) and Cronoamperometry (CA) in phosphate buffer (pH=7; I=0.2) to investigate the sensing properties of this material against H2O2. The electrochemical performances of proposed sensors as high sensitivity, fast response, reproducibility and selectivity make them suitable for the quantitative determination of hydrogen peroxide substrate in batch analysis. Copyright © 2015 Elsevier B.V. All rights reserved.

21 CFR 184.1366 - Hydrogen peroxide.

Code of Federal Regulations, 2014 CFR

2014-04-01

... 21 Food and Drugs 3 2014-04-01 2014-04-01 false Hydrogen peroxide. 184.1366 Section 184.1366 Food... GRAS § 184.1366 Hydrogen peroxide. (a) Hydrogen peroxide (H2O2, CAS Reg. No. 7722-84-1) is also referred to as hydrogen dioxide. It is made by the electrolytic oxidation of sulfuric acid or a sulfate to...

H2O2_COD_EPA; MEC_acclimation

EPA Pesticide Factsheets

H2O2_COD_EPA: Measurements of hydrogen peroxide and COD concentrations for water samples from the MEC reactors.MEC_acclimation: raw data for current and voltage of the anode in the MEC reactor.This dataset is associated with the following publication:Sim, J., J. An, E. Elbeshbishy, R. Hodon, and H. Lee. Characterization and optimization of cathodic conditions for H2O2 synthesis in microbial electrochemical cells. Bioresource Technology. Elsevier Online, New York, NY, USA, 195: 31-36, (2015).

Distillation Kinetics of Solid Mixtures of Hydrogen Peroxide and Water and the Isolation of Pure Hydrogen Peroxide in Ultrahigh Vacuum

NASA Technical Reports Server (NTRS)

Teolis, B. D.; Baragiola, R. A.

2006-01-01

We present results of the growth of thin films of crystalline H2O2 and H2O2.2H2O (dihydrate) in ultrahigh vacuum by distilling an aqueous solution of hydrogen peroxide. We traced the process using infrared reflectance spectroscopy, mass loss on a quartz crystal microbalance, and in a few cases ultraviolet-visible reflectance. We find that the different crystalline phases-water, dihydrate, and hydrogen peroxide-have very different sublimation rates, making distillation efficient to isolate the less volatile component, crystalline H2O2.

One- or two-electron water oxidation, hydroxyl radical, or H 2O 2 evolution

DOE PAGES

Siahrostami, Samira; Li, Guo -Ling; Viswanathan, Venkatasubramanian; ...

2017-02-23

Electrochemical or photoelectrochemcial oxidation of water to form hydrogen peroxide (H 2O 2) or hydroxyl radicals (•OH) offers a very attractive route to water disinfection, and the first process could be the basis for a clean way to produce hydrogen peroxide. A major obstacle in the development of effective catalysts for these reactions is that the electrocatalyst must suppress the thermodynamically favored four-electron pathway leading to O 2 evolution. Here, we develop a thermochemical picture of the catalyst properties that determine selectivity toward the one, two, and four electron processes leading to •OH, H 2O 2, and O 2.

Improved Electrolytic Hydrogen Peroxide Generator

NASA Technical Reports Server (NTRS)

James, Patrick I.

2005-01-01

An improved apparatus for the electrolytic generation of hydrogen peroxide dissolved in water has been developed. The apparatus is a prototype of H2O2 generators for the safe and effective sterilization of water, sterilization of equipment in contact with water, and other applications in which there is need for hydrogen peroxide at low concentration as an oxidant. Potential applications for electrolytic H2O2 generators include purification of water for drinking and for use in industrial processes, sanitation for hospitals and biotechnological industries, inhibition and removal of biofouling in heat exchangers, cooling towers, filtration units, and the treatment of wastewater by use of advanced oxidation processes that are promoted by H2O2.

Generation of H2, O2, and H2O2 from water by the use of intense femtosecond laser pulses and the possibility of laser sterilization

NASA Astrophysics Data System (ADS)

Chin, S. L.; Lagacé, S.

1996-02-01

An intense femtosecond Ti-sapphire laser pulse was focused into water, leading to self-focusing. Apart from generating a white light (supercontinuum), the intense laser field in the self-focusing regions of the laser pulse dissociated the water molecules, giving rise to hydrogen and oxygen gas as well as hydrogen peroxide. Our analysis shows that the formation of free radicals O, H, and OH preceded the formation of the stable products of H2, O2, and H2O2. Because O radicals and H2O2 are strong oxydizing agents, one can take advantage of this phenomenon to design a laser scheme for sterilization in medical and biological applications.

Photogeneration of H2O2 in SPEEK/PVA aqueous polymer solutions.

PubMed

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

2013-05-23

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

The influences of shape and structure of MnO2 nanomaterials over the non-enzymatic sensing ability of hydrogen peroxide

NASA Astrophysics Data System (ADS)

Babu, K. Justice; Zahoor, Awan; Nahm, Kee Suk; Ramachandran, R.; Rajan, M. A. Jothi; Gnana kumar, G.

2014-02-01

The different morphologies of MnO2 nanomaterials such as rod, belt, and flower were synthesized through a facile hydrothermal method, and their phases were also effectively controlled without employing any organic surfactants. The growth mechanisms of prepared nanostructures has been rationalized through the observed morphologic and structural characterizations. The prepared MnO2 nanostructures improved the electron transfer kinetics and minimized the overpotential and exhibited good electrocatalytic activities in detecting the hydrogen peroxide. Among the studied nanostructures, r-MnO2 exhibited an excellent sensing behavior toward hydrogen peroxide, and a linear current response was observed for the hydrogen peroxide, ranging from 1 micromolar to 1.5 mM with a high-sensitivity and low-level detection limit of 62.9 μAmM-1 cm-2 and 0.1 μM, respectively. Moreover, r-MnO2-modified electrode exhibited high selectivity toward hydrogen peroxide and interference-free phenomenon for the other electroactive species.

Bacillus pumilus KatX2 confers enhanced hydrogen peroxide resistance to a Bacillus subtilis PkatA::katX2 mutant strain.

PubMed

Handtke, Stefan; Albrecht, Dirk; Zühlke, Daniela; Otto, Andreas; Becher, Dörte; Schweder, Thomas; Riedel, Kathrin; Hecker, Michael; Voigt, Birgit

2017-04-26

Bacillus pumilus cells exhibit a significantly higher resistance to hydrogen peroxide compared to closely related Bacilli like Bacillus subtilis. In this study we analyzed features of the catalase KatX2 of B. pumilus as one of the most important parts of the cellular response to hydrogen peroxide. KatX2, the vegetative catalase expressed in B. pumilus, was compared to the vegetative catalase KatA of B. subtilis. Data of our study demonstrate that B. pumilus can degrade toxic concentrations of hydrogen peroxide faster than B. subtilis. By replacing B. subtilis katA gene by katX2 we could significantly enhance its resistance to H 2 O 2 and its potential to eliminate this toxic compound. Mutant cells showed a 1.5- to 2-fold higher survival to toxic concentrations of hydrogen peroxide compared to wild type cells. Furthermore, we found reversible but also irreversible oxidations of the KatX2 protein which, in contrast to KatA, contains several cysteine residues. Our study indicates that the catalase KatX2 plays a major role in the increased resistance of B. pumilus to oxidative stress caused by hydrogen peroxide. Resistance to hydrogen peroxide of other Bacilli can be enhanced by exchanging the native catalase in the cells with katX2.

A systemic investigation of hydrogen peroxide clusters (H2O2)n (n = 1-6) and liquid-state hydrogen peroxide: based on atom-bond electronegativity equalization method fused into molecular mechanics and molecular dynamics.

PubMed

Yu, Chun-Yang; Yang, Zhong-Zhi

2011-03-31

Hydrogen peroxide (HP) clusters (H(2)O(2))(n) (n = 1-6) and liquid-state HP have been systemically investigated by the newly constructed ABEEM/MM fluctuating charge model. Because of the explicit description of charge distribution and special treatment of the hydrogen-bond interaction region, the ABEEM/MM potential model gives reasonable properties of HP clusters, including geometries, interaction energies, and dipole moments, when comparing with the present ab initio results. Meanwhile, the average dipole moment, static dielectric constant, heats of vaporization, radial distribution function, and diffusion constant for the dynamic properties of liquid HP at 273 K and 1 atm are fairly consistent with the available experimental data. To the best of our knowledge, this is the first theoretical investigation of condensed HP. The properties of HP monomer are studied in detail involving the structure, torsion potentials, molecular orbital analysis, charge distribution, dipole moment, and vibrational frequency.

Electrodeposited nanostructured MnO{sub 2} for non-enzymatic hydrogen peroxide sensing

DOE Office of Scientific and Technical Information (OSTI.GOV)

Saha, B., E-mail: barnamala.saha@gmail.com; Jana, S. K.; Banerjee, S.

2015-06-24

Electrodeposited MnO{sub 2} 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.

A Facile One-Pot Synthesis of Au/Cu2O Nanocomposites for Nonenzymatic Detection of Hydrogen Peroxide

NASA Astrophysics Data System (ADS)

Chen, Ting; Tian, Liangliang; Chen, Yuan; Liu, Bitao; Zhang, Jin

2015-06-01

Au/Cu2O nanocomposites were successfully synthesized by a facile one-pot redox reaction without additional reducing agent under room temperature. The morphologies and structures of the as-prepared products were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), and X-ray diffraction (XRD). The electrocatalytic performance of Au/Cu2O nanocomposites towards hydrogen peroxide was evaluated by cyclic voltammetry (CV) and chronoamperometry (CA). The prepared Au/Cu2O nanocomposite electrode showed a wide linear range from 25 to 11.2 mM ( R = 0.9989) with a low detection limit of 1.05 μM ( S/ N = 3) and high sensitivity of 292.89 mA mM-1 cm-2. The enhanced performance for H2O2 detection can be attributed to the introduction of Au and the synergistic effect between Au and Cu2O. It is demonstrated that the Au/Cu2O nanocomposites material could be a promising candidate for H2O2 detection.

Direct N2H4/H2O2 Fuel Cells Powered by Nanoporous Gold Leaves

PubMed Central

Yan, Xiuling; Meng, Fanhui; Xie, Yun; Liu, Jianguo; Ding, Yi

2012-01-01

Dealloyed nanoporous gold leaves (NPGLs) are found to exhibit high electrocatalytic properties toward both hydrazine (N2H4) oxidation and hydrogen peroxide (H2O2) reduction. This observation allows the implementation of a direct hydrazine-hydrogen peroxide fuel cell (DHHPFC) based on these novel porous membrane catalysts. The effects of fuel and oxidizer flow rate, concentration and cell temperature on the performance of DHHPFC are systematically investigated. With a loading of ~0.1 mg cm−2 Au on each side, an open circuit voltage (OCV) of 1.2 V is obtained at 80°C with a maximum power density 195 mW cm−2, which is 22 times higher than that of commercial Pt/C electrocatalyst at the same noble metal loading. NPGLs thus hold great potential as effective and stable electrocatalysts for DHHPFCs. PMID:23230507

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

PubMed

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

2015-02-26

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

Mechanistic study of photo-oxidation of Bisphenol-A (BPA) with hydrogen peroxide (H2O2) and sodium persulfate (SPS).

PubMed

Sharma, Jyoti; Mishra, I M; Kumar, Vineet

2016-01-15

The removal of Bisphenol-A (BPA) from contaminated water using advanced oxidation methods such as UV-C assisted oxidation by hydrogen peroxide (H2O2) and sodium persulfate (SPS) has been reported by the authors earlier (Sharma et al., 2015a). In the present study, the authors report the removal of BPA from aqueous solution by the above two methods and its degradation mechanism. UV-C light (254 nm wavelength, 40 W power) was applied to BPA contaminated water at natural pH (pHN) under room temperature conditions. Experiments were carried out with the initial BPA concentration in the range of 0.04 mM-0.31 mM and the oxidant/BPA molar ratio in the range of 294:1-38:1 for UV-C/H2O2 and 31.5-4.06:1 for UV-C/SPS systems. The removal of BPA enhanced with decreasing BPA concentration. The total organic carbon also decreased with the UV-C irradiation time under optimum conditions ([H2O2]0 = 11.76 mM; [SPS]0 = 1.26 mM; temperature (29 ± 3 °C). Competition of BPA for reaction with HO or [Formula: see text] radicals at its higher concentrations results in a decrease in the removal of BPA. The intermediates with smaller and higher molecular weights than that of BPA were found in the treated water. Based on GC-MS and FTIR spectra of the reaction mixture, the formation of hydroxylated by-products testified the HO mediated oxidation pathway in the BPA degradation, while the formation of quinones and phenoxy phenols pointed to the [Formula: see text] dominating pathway through the formation of hydroxycyclohexadienyl (HCHD) and BPA phenoxyl radicals. The main route of BPA degradation is the hydroxylation followed by dehydration, coupling and ring opening reactions. Copyright © 2015 Elsevier Ltd. All rights reserved.

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

PubMed

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. Copyright © 2016 Elsevier B.V. All rights reserved.

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

PubMed

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

2011-07-01

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

Desferrioxamine as an electron donor. Inhibition of membranal lipid peroxidation initiated by H2O2-activated metmyoglobin and other peroxidizing systems.

PubMed

Kanner, J; Harel, S

1987-01-01

Desferrioxamine (DFO) involvement in several peroxidative systems was studied. These systems included: a) membranal lipid peroxidation initiated by H2O2-activated metmyoglobin (or methemoglobin); b) phenol-red oxidation by activated metmyoglobin or horseradish peroxidase (HRP): c) beta-carotene-linoleate couple oxidation stimulated by lipoxygenase or hemin. Desferrioxamine was found to inhibit all these systems but not ferrioxamine (FO). Phenol-red oxidation by H2O2-horseradish peroxidase was inhibited competitively with DFO. Kinetic studies using the spectra changes in the Soret region of metmyoglobin suggest a mechanism by which H2O2 reacts with the iron-heme to form an intermediate of oxy-ferryl myoglobin that subsequently reacts with DFO to return the activated compound to the resting state. These activities of DFO resemble the reaction of other electron donors.

Selective electrochemical generation of hydrogen peroxide from water oxidation

DOE PAGES

Viswanathan, Venkatasubramanian; Hansen, Heine A.; Norskov, Jens K.

2015-10-08

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, wemore » show that the free energy of adsorbed OH* can be used to determine selectivity trends between the 2e– water oxidation to H 2O 2 and the 4e– oxidation to O 2. We show that materials which bind oxygen intermediates sufficiently weakly, such as SnO 2, can activate hydrogen peroxide evolution. Furthermore, we present a rational design principle for the selectivity in electrochemical water oxidation and identify new material candidates that could perform H 2O 2 evolution selectively.« less

Refinements in an Mg/MgH2/H2O-Based Hydrogen Generator

NASA Technical Reports Server (NTRS)

Kindler, Andrew; Huang, Yuhong

2010-01-01

Some refinements have been conceived for a proposed apparatus that would generate hydrogen (for use in a fuel cell) by means of chemical reactions among magnesium, magnesium hydride, and steam. The refinements lie in tailoring spatial and temporal distributions of steam and liquid water so as to obtain greater overall energy-storage or energy-generation efficiency than would otherwise be possible. A description of the prior art is prerequisite to a meaningful description of the present refinements. The hydrogen-generating apparatus in question is one of two versions of what was called the "advanced hydrogen generator" in "Fuel-Cell Power Systems Incorporating Mg-Based H2 Generators" (NPO-43554), NASA Tech Briefs, Vol. 33, No. 1 (January 2009), page 52. To recapitulate: The apparatus would include a reactor vessel that would be initially charged with magnesium hydride. The apparatus would exploit two reactions: The endothermic decomposition reaction MgH2-->Mg + H2, which occurs at a temperature greater than or equal to 300 C, and The exothermic oxidation reaction MgH2 + H2O MgO + 2H2, which occurs at a temperature greater than or equal to 330 C.

Stabilized aqueous hydrogen peroxide solution

DOE Office of Scientific and Technical Information (OSTI.GOV)

Malin, M.J.; Sciafani, L.D.

1988-05-17

This patent describes a stabilized aqueous hydrogen peroxide solution having a pH below 7 and an amount of Ferric ion up to about 2 ppm comprising hydrogen peroxide, acetanilide having a concentration which ranges between 0.74 M Mol/L and 2.22 mMol/L, and o-benzene disulfonic acid or salt thereof at a concentration between about 0.86 mMol/L to about 1.62 mMol/L.

Interfacial contributions of H2O2 decomposition-induced reaction current on mesoporous Pt/TiO2 systems

NASA Astrophysics Data System (ADS)

Ray, Nathan J.; Styrov, Vladislav V.; Karpov, Eduard G.

2017-12-01

We report on conversion of energy released due to chemical reactions into current for the decomposition of aqueous hydrogen peroxide solution on single phases Pt and TiO2, in addition to Pt and TiO2 simultaneously. We observe that H2O2 decomposition-induced current on TiO2 drastically overshadows the current generated by H2O2 decomposition on Pt. Photo-effects avoided, H2O2 decomposition was found to yield a conversion efficiency of 10-3 electrons generated per H2O2 molecule. Further understanding of chemical reaction-induced current shows promise as a metric with which the surface reaction may be monitored and could be greatly extended into the field of analytical chemistry.

Different Modes of Hydrogen Peroxide Action During Seed Germination

PubMed Central

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

Development of an E-H2O2/TiO2 photoelectrocatalytic oxidation system for water and wastewater treatment.

PubMed

Li, X Z; Liu, H S

2005-06-15

In this study, an innovative E-H2O2/TiO2 (E-H2O2 = electrogenerated hydrogen peroxide) photoelectrocatalytic (PEC) oxidation system was successfully developed for water and wastewater treatment. A TiO2/Ti mesh electrode was applied in this photoreactor as the anode to conduct PEC oxidation, and a reticulated vitreous carbon (RVC) electrode was used as the cathode to electrogenerate hydrogen peroxide simultaneously. The TiO2/Ti mesh electrode was prepared with a modified anodic oxidation process in a quadrielectrolyte (H2SO4-H3PO4-H2O2-HF) solution. The crystal structure, surface morphology, and film thickness of the TiO2/Ti mesh electrode were characterized by X-ray diffraction and scanning electron microscopy. The analytical results showed that a honeycomb-type anatase film with a thickness of 5 microm was formed. Photocatalytic oxidation (PC) and PEC oxidation of 2,4,6-trichlorophenol (TCP) in an aqueous solution were performed under various experimental conditions. Experimental results showed that the TiO2/Ti electrode, anodized in the H2SO4-H3PO4-H2O2-HF solution, had higher photocatalytic activity than the TiO2/Ti electrode anodized in the H2SO4 solution. It was found that the maximum applied potential would be around 2.5 V, corresponding to an optimum applied current density of 50 microA cm(-2) under UV-A illumination. The experiments confirmed that the E-H2O2 on the RVC electrode can significantly enhance the PEC oxidation of TCP in aqueous solution. The rate of TCP degradation in such an E-H2O2-assisted TiO2 PEC reaction was 5.0 times that of the TiO2 PC reaction and 2.3 times that of the TiO2 PEC reaction. The variation of pH during the E-H2O2-assisted TiO2 PEC reaction, affected by individual reactions, was also investigated. It was found that pH was well maintained during the TCP degradation in such an E-H2O2/TiO2 reaction system. This is beneficial to TCP degradation in an aqueous solution.

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

NASA Astrophysics Data System (ADS)

Wen, Zuoqiang; Zou, Linbo; Wang, Weiming

2018-03-01

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

Improved hydrogen storage properties of MgH2 catalyzed with TiO2

NASA Astrophysics Data System (ADS)

Jangir, Mukesh; Meena, Priyanka; Jain, I. P.

2018-05-01

In order to improve the hydrogenation properties of the MgH2, various concentration of rutile Titanium Oxide (TiO2) (X wt%= 5, 10, 15 wt %) is added to MgH2 by ball milling and the catalytic effect of TiO2 on hydriding/dehydriding properties of MgH2 has been investigated. Result shows that the TiO2 significantly reduced onset temperature of desorption. Onset temperature as low as 190 °C were observed for the MgH2-15 wt% TiO2 sample which is 60 °C and 160 °C lower than the as-milled and as-received MgH2. Fromm the Kissinger plot the activation energy of 15 wt% TiO2 added sample is calculated to be -75.48 KJ/mol. These results indicate that the hydrogenation properties of MgH2-TiO2 have been improved compared to the as-milled and as-received MgH2. Furthermore, XRD and XPS were performed to characterize the structural evolution upon milling and dehydrogenation.

Electrochemical, H2O2-Boosted Catalytic Oxidation System

NASA Technical Reports Server (NTRS)

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

2004-01-01

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

ESR investigation of ROS generated by H2O2 bleaching with TiO2 coated HAp.

PubMed

Saita, Makiko; Kobayashi, Kyo; Kobatashi, Kyou; Yoshino, Fumihiko; Hase, Hiriko; Nonami, Toru; Kimoto, Katsuhiko; Lee, Masaichi-Chang-il

2012-01-01

It is well known that clinical bleaching can be achieved with a solution of 30% hydrogen peroxide (H2O2) or H2O2/titanium dioxide (TiO2) combination. This study examined the hypothesis that TiO2 coated with hydroxyapatite (HAp-TiO2) can generate reactive oxygen species (ROS). ROS are generated via photocatalysis using electron spin resonance (ESR). The bleaching properties of HAp-TiO2 in the presence of H2O2 can be measured using hematoporphyrin litmus paper and extracted teeth. We demonstrate that superoxides (O2(•-)) and hydroxyl radicals (HO(•)) can be generated through excitation of anatase TiO2, rutile TiO2, anatase HAp-TiO2, and rutile HAp-TiO2 in the presence of H2O2. The combination of R HAp-TiO2 with H2O2 produced the highest level of HO(•) generation and the most marked bleaching effects of all the samples. The superior bleaching effects exhibited by R HAp-TiO2 with H2O2 suggest that this combination may lead to novel methods for the clinical application of bleaching treatments.

Effect of hydrogen peroxide on antibacterial activities of Canadian honeys.

PubMed

Brudzynski, Katrina

2006-12-01

Honey is recognized as an efficacious topical antimicrobial agent in the treatment of burns and wounds. The antimicrobial activity in some honeys depends on the endogenous hydrogen peroxide content. This study was aimed to determine whether honey's hydrogen peroxide level could serve as a honey-specific, activity-associated biomarker that would allow predicting and assessing the therapeutic effects of honey. Using a broth microdilution assay, I analyzed antibacterial activities of 42 Canadian honeys against two bacterial strains: Escherichia coli (ATCC 14948) and Bacillus subtilis (ATCC 6633). The MIC90 and MIC50 were established from the dose-response relationship between antibacterial activities and honey concentrations. The impact of H2O2 on antibacterial activity was determined (i) by measuring the levels of H2O2 before and after its removal by catalase and (ii) by correlating the results with levels of antibacterial activities. Canadian honeys demonstrated moderate to high antibacterial activity against both bacterial species. Both MIC90 and MIC50 revealed that the honeys exhibited a selective growth inhibitory activity against E. coli, and this activity was strongly influenced by endogenous H2O2 concentrations. Bacillus subtilis activity was marginally significantly correlated with H2O2 content. The removal of H2O2 by catalase reduced the honeys' antibacterial activity, but the enzyme was unable to completely decompose endogenous H2O2. The 25%-30% H2O2 "leftover" was significantly correlated with the honeys' residual antibacterial activity against E. coli. These data indicate that all Canadian honeys exhibited antibacterial activity, with higher selectivity against E. coli than B. subtilis, and that these antibacterial activities were correlated with hydrogen peroxide production in honeys. Hydrogen peroxide levels in honey, therefore, is a strong predictor of the honey's antibacterial activity.

A reaction-diffusion model of cytosolic hydrogen peroxide.

PubMed

Lim, Joseph B; Langford, Troy F; Huang, Beijing K; Deen, William M; Sikes, Hadley D

2016-01-01

As a signaling molecule in mammalian cells, hydrogen peroxide (H2O2) determines the thiol/disulfide oxidation state of several key proteins in the cytosol. Localization is a key concept in redox signaling; the concentrations of signaling molecules within the cell are expected to vary in time and in space in manner that is essential for function. However, as a simplification, all theoretical studies of intracellular hydrogen peroxide and many experimental studies to date have treated the cytosol as a well-mixed compartment. In this work, we incorporate our previously reported reduced kinetic model of the network of reactions that metabolize hydrogen peroxide in the cytosol into a model that explicitly treats diffusion along with reaction. We modeled a bolus addition experiment, solved the model analytically, and used the resulting equations to quantify the spatiotemporal variations in intracellular H2O2 that result from this kind of perturbation to the extracellular H2O2 concentration. We predict that micromolar bolus additions of H2O2 to suspensions of HeLa cells (0.8 × 10(9)cells/l) result in increases in the intracellular concentration that are localized near the membrane. These findings challenge the assumption that intracellular concentrations of H2O2 are increased uniformly throughout the cell during bolus addition experiments and provide a theoretical basis for differing phenotypic responses of cells to intracellular versus extracellular perturbations to H2O2 levels. Copyright © 2015 Elsevier Inc. All rights reserved.

Engineering bacterial motility towards hydrogen-peroxide.

PubMed

Virgile, Chelsea; Hauk, Pricila; Wu, Hsuan-Chen; Shang, Wu; Tsao, Chen-Yu; Payne, Gregory F; Bentley, William E

2018-01-01

Synthetic biologists construct innovative genetic/biological systems to treat environmental, energy, and health problems. Many systems employ rewired cells for non-native product synthesis, while a few have employed the rewired cells as 'smart' devices with programmable function. Building on the latter, we developed a genetic construct to control and direct bacterial motility towards hydrogen peroxide, one of the body's immune response signaling molecules. A motivation for this work is the creation of cells that can target and autonomously treat disease, the latter signaled by hydrogen peroxide release. Bacteria naturally move towards a variety of molecular cues (e.g., nutrients) in the process of chemotaxis. In this work, we engineered bacteria to recognize and move towards hydrogen peroxide, a non-native chemoattractant and potential toxin. Our system exploits oxyRS, the native oxidative stress regulon of E. coli. We first demonstrated H2O2-mediated upregulation motility regulator, CheZ. Using transwell assays, we showed a two-fold increase in net motility towards H2O2. Then, using a 2D cell tracking system, we quantified bacterial motility descriptors including velocity, % running (of tumble/run motions), and a dynamic net directionality towards the molecular cue. In CheZ mutants, we found that increased H2O2 concentration (0-200 μM) and induction time resulted in increased running speeds, ultimately reaching the native E. coli wild-type speed of ~22 μm/s with a ~45-65% ratio of running to tumbling. Finally, using a microfluidic device with stable H2O2 gradients, we characterized responses and the potential for "programmed" directionality towards H2O2 in quiescent fluids. Overall, the synthetic biology framework and tracking analysis in this work will provide a framework for investigating controlled motility of E. coli and other 'smart' probiotics for signal-directed treatment.

Innovative pretreatment of sugarcane bagasse using supercritical CO2 followed by alkaline hydrogen peroxide.

PubMed

Phan, Duy The; Tan, Chung-Sung

2014-09-01

An innovative method for pretreatment of sugarcane bagasse using sequential combination of supercritical CO2 (scCO2) and alkaline hydrogen peroxide (H2O2) at mild conditions is proposed. This method was found to be superior to the individual pretreatment with scCO2, ultrasound, or H2O2 and the sequential combination of scCO2 and ultrasound regarding the yield of cellulose and hemicellulose, almost twice the yield was observed. Pretreatment with scCO2 could obtain higher amount of cellulose and hemicellulose but also acid-insoluble lignin. Pretreatment with ultrasound or H2O2 could partly depolymerize lignin, however, could not separate cellulose from lignin. The analysis of liquid products via enzymatic hydrolysis by HPLC and the characterization of the solid residues by SEM revealed strong synergetic effects in the sequential combination of scCO2 and H2O2. Copyright © 2014 Elsevier Ltd. All rights reserved.

NOX4-dependent Hydrogen peroxide promotes shear stress-induced SHP2 sulfenylation and eNOS activation.

PubMed

Sánchez-Gómez, Francisco J; Calvo, Enrique; Bretón-Romero, Rosa; Fierro-Fernández, Marta; Anilkumar, Narayana; Shah, Ajay M; Schröder, Katrin; Brandes, Ralf P; Vázquez, Jesús; Lamas, Santiago

2015-12-01

Laminar shear stress (LSS) triggers signals that ultimately result in atheroprotection and vasodilatation. Early responses are related to the activation of specific signaling cascades. We investigated the participation of redox-mediated modifications and in particular the role of hydrogen peroxide (H2O2) in the sulfenylation of redox-sensitive phosphatases. Exposure of vascular endothelial cells to short periods of LSS (12 dyn/cm(2)) resulted in the generation of superoxide radical anion as detected by the formation of 2-hydroxyethidium by HPLC and its subsequent conversion to H2O2, which was corroborated by the increase in the fluorescence of the specific peroxide sensor HyPer. By using biotinylated dimedone we detected increased total protein sulfenylation in the bovine proteome, which was dependent on NADPH oxidase 4 (NOX4)-mediated generation of peroxide. Mass spectrometry analysis allowed us to identify the phosphatase SHP2 as a protein susceptible to sulfenylation under LSS. Given the dependence of FAK activity on SHP2 function, we explored the role of FAK under LSS conditions. FAK activation and subsequent endothelial NO synthase (eNOS) phosphorylation were promoted by LSS and both processes were dependent on NOX4, as demonstrated in lung endothelial cells isolated from NOX4-null mice. These results support the idea that LSS elicits redox-sensitive signal transduction responses involving NOX4-dependent generation of hydrogen peroxide, SHP2 sulfenylation, and ulterior FAK-mediated eNOS activation. Copyright © 2015 Elsevier Inc. All rights reserved.

Hydrogen peroxide-induced apoptosis in human gingival fibroblasts

PubMed Central

Gutiérrez-Venegas, Gloria; Guadarrama-Solís, Adriana; Muñoz-Seca, Carmen; Arreguín-Cano, Juan Antonio

2015-01-01

In the process of bleaching vital, discolored teeth, low concentrations of hydrogen peroxide (H2O2) are effective alternatives to heat-activated 30% H2O2. However, interest has been expressed in the assessment of pathological effects of long-term exposure to bleaching agents such as irritation and ulceration of the gingival or other soft tissues. The aim of the present study was to determine the effect of hydrogen peroxide on apoptosis in human gingival fibroblasts (HGF). Cytochrome c, Bcl-2, Bax, Bid and caspase-3 protein expression were detected by Western blotting. HGF cell apoptosis induced by H2O2 was both dose and time dependent. The addition of H2O2 resulted in the release of cytochrome c to the cytosol, and an increase of Caspase-3 cleavage. Data suggest that oxidative stress-induced apoptosis in HGF is intrinsic pathway involved the release of apoptotic signal from mitochondria. PMID:26884825

A highly sensitive hydrogen peroxide amperometric sensor based on MnO2-modified vertically aligned multiwalled carbon nanotubes.

PubMed

Xu, Bin; Ye, Min-Ling; Yu, Yu-Xiang; Zhang, Wei-De

2010-07-26

In this report, a highly sensitive amperometric sensor based on MnO(2)-modified vertically aligned multiwalled carbon nanotubes (MnO(2)/VACNTs) for determination of hydrogen peroxide (H(2)O(2)) was fabricated by electrodeposition. The morphology of the nanocomposite was characterized by scanning electron microscopy, energy-dispersive X-ray spectrometer and X-ray diffraction. Cyclic voltammetry, chronoamperometry and electrochemical impedance spectroscopy were applied to investigate the electrochemical properties of the MnO(2)/VACNTs nanocomposite electrode. The mechanism for the electrochemical reaction of H(2)O(2) at the MnO(2)/VACNTs nanocomposite electrode was also discussed. In borate buffer (pH 7.8, 0.20 M), the MnO(2)/VACNTs nanocomposite electrode exhibits a linear dependence (R=0.998) on the concentration of H(2)O(2) from 1.2 x 10(-6)M to 1.8 x 10(-3)M, a high sensitivity of 1.08 x 10(6) microA M(-1) cm(-2) and a detection limit of 8.0 x 10(-7) M (signal/noise=3). Meanwhile, the MnO(2)/VACNTs nanocomposite electrode is also highly resistant towards typical inorganic salts and some biomolecules such as acetic acid, citric acid, uric acid and D-(+)-glucose, etc. In addition, the sensor based on the MnO(2)/VACNTs nanocomposite electrode was applied for the determination of trace of H(2)O(2) in milk with high accuracy, demonstrating its potential for practical application. Copyright 2010 Elsevier B.V. All rights reserved.

Degradation and Byproduct Formation of Parathion in Aqueous Solutions by UV and UV/H2O2 Treatment

PubMed Central

Wu, Changlong; Linden, Karl G.

2013-01-01

The photodegradation of parathion, a US EPA Contaminant Candidate List pesticide, in aqueous solutions by UV and UV/H2O2 processes in batch reactors was evaluated. Direct photolysis of parathion both by LP (low pressure) and MP (medium pressure) lamps at pH 7 were very slow with quantum yields of 6.67 ± 0.33 ×10−4 and 6.00 ± 1.06 ×10−4 mol E−1, respectively. Hydrogen peroxide enhanced the photodegradation of parathion through the reaction between UV generated hydroxyl radical and parathion with a second-order reaction rate constant of 9.70 ± 0.45×109 M−1 s−1. However, addition of hydrogen peroxide did not result in a linear increase in the degradation rate. An optimum molar ratio between hydrogen peroxide and parathion was determined to be between 300 – 400. Photodegradation of parathion yielded several organic byproducts, of which the paraoxon, 4-nitrophenol, O,O,O-triethyl thiophosphate and O,O diethyl-methyl thiophosphate were quantified and their occurrence during UV/H2O2 processes were discussed. NO2−, PO43−, NO3− and SO42− were the major anionic byproducts of parathion photodegradation and their recover ratio were also discussed. A photodegradation mechanism scheme suggesting three simultaneous pathways was proposed in the study. PMID:18834610

D/H fractionation in the H2-H2O system at supercritical water conditions: Compositional and hydrogen bonding effects

NASA Astrophysics Data System (ADS)

Foustoukos, Dionysis I.; Mysen, Bjorn O.

2012-06-01

A series of experiments has been conducted in the H2-D2-D2O-H2O-Ti-TiO2 system at temperatures ranging from 300 to 800 °C and pressures between ∼0.3 and 1.3 GPa in a hydrothermal diamond anvil cell, utilizing Raman spectroscopy as a quantitative tool to explore the relative distribution of hydrogen and deuterium isotopologues of the H2 and H2O in supercritical fluids. In detail, H2O-D2O solutions (1:1) were reacted with Ti metal (3-9 h) in the diamond cell, leading to formation of H2, D2, HD, and HDO species through Ti oxidation and H-D isotope exchange reactions. Experimental results obtained in situ and at ambient conditions on quenched samples indicate significant differences from the theoretical estimates of the equilibrium thermodynamic properties of the H-D exchange reactions. In fact, the estimated enthalpy for the H2(aq)-D2(aq) disproportionation reaction (ΔHrxn) is about -3.4 kcal/mol, which differs greatly from the +0.16 kcal/mol predicted for the exchange reaction in the gas phase by statistical mechanics models. The exothermic behavior of the exchange reaction implies enhanced stability of H2 and D2 relative to HD. Accordingly, the significant energy difference of the internal H2(aq)-D2(aq)-HD(aq) equilibrium translates to strong differences of the fractionation effects between the H2O-H2 and D2O-D2 isotope exchange relationships. The D/H fractionation factors between H2O-H2(aq) and D2O-D2(aq) differ by 365‰ in the 600-800 °C temperature range, and are indicative of the greater effect of D2O contribution to the δD isotopic composition of supercritical fluids. The negative ΔHrxn values for the H2(aq)-D2(aq)-HD(aq) equilibrium and the apparent decrease of the equilibrium constant with increasing temperature might be because of differences of the Henry’s law constant between the H- and D-bearing species dissolved in supercritical aqueous solutions. Such effects may be attributed to the stronger hydrogen bonding in the O-H⋯O relative to the

Palladium-tin catalysts for the direct synthesis of H 2O 2 with high selectivity

DOE PAGES

Freakley, Simon J.; He, Qian; Harrhy, Jonathan H.; ...

2016-02-25

The direct synthesis of hydrogen peroxide (H 2O 2 ) from H 2 and O 2 represents a potentially atom-efficient alternative to the current industrial indirect process. We show that the addition of tin to palladium catalysts coupled with an appropriate heat treatment cycle switches off the sequential hydrogenation and decomposition reactions, enabling selectivities of >95% toward H 2O 2 . This effect arises from a tin oxide surface layer that encapsulates small Pd-rich particles while leaving larger Pd-Sn alloy particles exposed. In conclusion, we show that this effect is a general feature for oxide-supported Pd catalysts containing an appropriatemore » second metal oxide component, and we set out the design principles for producing high-selectivity Pd-based catalysts for direct H 2O 2 production that do not contain gold.« less

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

PubMed Central

Bihamta, Mehdi; Hosseini, Azar; Ghorbani, Ahmad; Boroushaki, Mohammad Taher

2017-01-01

Objective: It has been well documented that oxidative stress is involved in the pathogenesis of cardiac diseases. Previous studies have shown that pomegranate seed oil (PSO) has antioxidant properties. This study was designed to investigate probable protective effects of PSO against hydrogen peroxide (H2O2)-induced damage in H9c2 cardiomyocytes. Materials and Methods: The cells were pretreated 24 hr with PSO 1 hr before exposure to 200 µM H2O2. Cell viability was evaluated using 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium (MTT) assay. The level of reactive oxygen species (ROS) and lipid peroxidation were measured by fluorimetric methods. Results: H2O2 significantly decreased cell viability which was accompanied by an increase in ROS production and lipid peroxidation and a decline in superoxide dismutase activity. Pretreatment with PSO increased viability of cardiomyocytes and decrease the elevated ROS production and lipid peroxidation. Also, PSO was able to restore superoxide dismutase activity. Conclusion: PSO has protective effect against oxidative stress-induced damage in cardiomyocytes and can be considered as a natural cardioprotective agent to prevent cardiovascular diseases. PMID:28265546

Yield of H2O2 in Gas-Liquid Phase with Pulsed DBD

NASA Astrophysics Data System (ADS)

Jiang, Song; Wen, Yiyong; Liu, Kefu

2014-01-01

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

Esculetin-induced protection of human hepatoma HepG2 cells against hydrogen peroxide is associated with the Nrf2-dependent induction of the NAD(P)H: Quinone oxidoreductase 1 gene

DOE Office of Scientific and Technical Information (OSTI.GOV)

Subramaniam, Sudhakar R.; Ellis, Elizabeth M., E-mail: elizabeth.ellis@strath.ac.uk

Esculetin (6,7-dihydroxy coumarin), is a potent antioxidant that is present in several plant species. The aim of this study was to investigate the mechanism of protection of esculetin in human hepatoma HepG2 cells against reactive oxygen species (ROS) induced by hydrogen peroxide. Cell viability, cell integrity, intracellular glutathione levels, generation of reactive oxygen species and expression of antioxidant enzymes were used as markers to measure cellular oxidative stress and response to ROS. The protective effect of esculetin was compared to a well-characterized chemoprotective compound quercetin. Pre-treatment of HepG2 cells with sub-lethal (10-25 {mu}M) esculetin for 8 h prevented cell deathmore » and maintained cell integrity following exposure to 0.9 mM hydrogen peroxide. An increase in the generation of ROS following hydrogen peroxide treatment was significantly attenuated by 8 h pre-treatment with esculetin. In addition, esculetin ameliorated the decrease in intracellular glutathione caused by hydrogen peroxide exposure. Moreover, treatment with 25 {mu}M esculetin for 8 h increased the expression of NAD(P)H: quinone oxidoreductase (NQO1) at both protein and mRNA levels significantly, by 12-fold and 15-fold, respectively. Esculetin treatment also increased nuclear accumulation of Nrf2 by 8-fold indicating that increased NQO1 expression is Nrf2-mediated. These results indicate that esculetin protects human hepatoma HepG2 cells from hydrogen peroxide induced oxidative injury and that this protection is provided through the induction of protective enzymes as part of an adaptive response mediated by Nrf2 nuclear accumulation.« less

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

NASA Astrophysics Data System (ADS)

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

2016-03-01

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

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

NASA Astrophysics Data System (ADS)

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

2012-03-01

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

Hydrogen peroxide stabilization in one-dimensional flow columns

NASA Astrophysics Data System (ADS)

Schmidt, Jeremy T.; Ahmad, Mushtaque; Teel, Amy L.; Watts, Richard J.

2011-09-01

Rapid hydrogen peroxide decomposition is the primary limitation of catalyzed H 2O 2 propagations in situ chemical oxidation (CHP ISCO) remediation of the subsurface. Two stabilizers of hydrogen peroxide, citrate and phytate, were investigated for their effectiveness in one-dimensional columns of iron oxide-coated and manganese oxide-coated sand. Hydrogen peroxide (5%) with and without 25 mM citrate or phytate was applied to the columns and samples were collected at 8 ports spaced 13 cm apart. Citrate was not an effective stabilizer for hydrogen peroxide in iron-coated sand; however, phytate was highly effective, increasing hydrogen peroxide residuals two orders of magnitude over unstabilized hydrogen peroxide. Both citrate and phytate were effective stabilizers for manganese-coated sand, increasing hydrogen peroxide residuals by four-fold over unstabilized hydrogen peroxide. Phytate and citrate did not degrade and were not retarded in the sand columns; furthermore, the addition of the stabilizers increased column flow rates relative to unstabilized columns. These results demonstrate that citrate and phytate are effective stabilizers of hydrogen peroxide under the dynamic conditions of one-dimensional columns, and suggest that citrate and phytate can be added to hydrogen peroxide before injection to the subsurface as an effective means for increasing the radius of influence of CHP ISCO.

Effect of cementum defects on radicular penetration of 30% H2O2 during intracoronal bleaching.

PubMed

Rotstein, I; Torek, Y; Misgav, R

1991-05-01

Bleaching pulpless teeth with 30% hydrogen peroxide has been reported to cause external cervical root resorption. It has been hypothesized that H2O2 penetrating through open dentin tubules can initiate an inflammatory reaction which could result in root resorption. Extracted human premolars were treated endodontically and bleached intracoronally using the thermocatalytic technique. The teeth were divided into three groups; one group with no cementum defects at the cementoenamel junction, one group with artificial cementum defects at the cementoenamel junction, and another group with artificial cementum defects at the middle third of the root. The radicular penetration of 30% hydrogen peroxide in the three groups was assessed directly and compared using an in vitro model. Radicular penetration of hydrogen peroxide was found in all of the groups tested. The penetration of hydrogen peroxide was significantly higher in teeth with cementum defects at the cementoenamel junction than in those without defects.

Kinetic Modeling of Methionine Oxidation in Monoclonal Antibodies from Hydrogen Peroxide Spiking Studies.

PubMed

Hui, Ada; Lam, Xanthe M; Kuehl, Christopher; Grauschopf, Ulla; Wang, Y John

2015-01-01

When isolator technology is applied to biotechnology drug product fill-finish process, hydrogen peroxide (H2O2) spiking studies for the determination of the sensitivity of protein to residual peroxide in the isolator can be useful for assessing a maximum vapor phase hydrogen peroxide (VPHP) level. When monoclonal antibody (mAb) drug products were spiked with H2O2, an increase in methionine (Met 252 and Met 428) oxidation in the Fc region of the mAbs with a decrease in H2O2 concentration was observed for various levels of spiked-in peroxide. The reaction between Fc-Met and H2O2 was stoichiometric (i.e., 1:1 molar ratio), and the reaction rate was dependent on the concentrations of mAb and H2O2. The consumption of H2O2 by Fc-Met oxidation in the mAb followed pseudo first-order kinetics, and the rate was proportional to mAb concentration. The extent of Met 428 oxidation was half of that of Met 252, supporting that Met 252 is twice as reactive as Met 428. Similar results were observed for free L-methionine when spiked with H2O2. However, mAb formulation excipients may affect the rate of H2O2 consumption. mAb formulations containing trehalose or sucrose had faster H2O2 consumption rates than formulations without the sugars, which could be the result of impurities (e.g., metal ions) present in the excipients that may act as catalysts. Based on the H2O2 spiking study results, we can predict the amount Fc-Met oxidation for a given protein concentration and H2O2 level. Our kinetic modeling of the reaction between Fc-Met oxidation and H2O2 provides an outline to design a H2O2 spiking study to support the use of VPHP isolator for antibody drug product manufacture. Isolator technology is increasing used in drug product manufacturing of biotherapeutics. In order to understand the impact of residual vapor phase hydrogen peroxide (VPHP) levels on protein product quality, hydrogen peroxide (H2O2) spiking studies may be performed to determine the sensitivity of monoclonal antibody

Flow cytometric HyPer-based assay for hydrogen peroxide.

PubMed

Lyublinskaya, O G; Antonov, S A; Gorokhovtsev, S G; Pugovkina, N A; Kornienko, Ju S; Ivanova, Ju S; Shatrova, A N; Aksenov, N D; Zenin, V V; Nikolsky, N N

2018-05-30

HyPer is a genetically encoded fluorogenic sensor for hydrogen peroxide which is generally used for the ratiometric imaging of H 2 O 2 fluxes in living cells. Here, we demonstrate the advantages of HyPer-based ratiometric flow cytometry assay for H 2 O 2 , by using K562 and human mesenchymal stem cell lines expressing HyPer. We show that flow cytometry analysis is suitable to detect HyPer response to submicromolar concentrations of extracellularly added H 2 O 2 that is much lower than concentrations addressed previously in the other HyPer-based assays (such as cell imaging or fluorimetry). Suggested technique is also much more sensitive to hydrogen peroxide than the widespread flow cytometry assay exploiting H 2 O 2 -reactive dye H 2 DCFDA and, contrary to the H 2 DCFDA-based assay, can be employed for the kinetic studies of H 2 O 2 utilization by cells, including measurements of the rate constants of H 2 O 2 removal. In addition, flow cytometry multi-parameter ratiometric measurements enable rapid and high-throughput detection of endogenously generated H 2 O 2 in different subpopulations of HyPer-expressing cells. To sum up, HyPer can be used in multi-parameter flow cytometry studies as a highly sensitive indicator of intracellular H 2 O 2 . Copyright © 2018. Published by Elsevier Inc.

Kinetics of the Bicarbonate-Assisted Oxidation of Diethyl Sulfide by Hydrogen Peroxide and Sodium Peroxoborate

NASA Astrophysics Data System (ADS)

Dyatlenko, L. M.; Lobachev, V. L.; Bezbozhnaya, T. V.

2018-07-01

The kinetics of oxidation of diethyl sulfide (Et2S) is studied in aqueous solutions of hydrogen peroxide and sodium peroxoborate (Na2[B2(O2)2(OH)4]) in the presence of bicarbonate ions by means of gas-liquid distribution. The kinetics is investigated in a broad range of pH. Data show that the oxidation of Et2S by sodium peroxoborate in the range of pH 6-12 is mediated by such reactive species as hydrogen peroxide, hydrogen peroxide anions, and mono (B(O2H)(OH)3^{ - }) and diperoxoborate (B(O2H)2(OH)2^{ - }2->) anions. The rate of Et2S oxidation increases in the presence of bicarbonate, due to the additional reaction pathways mediated by monoperoxocarbonate species.

Efficacy, efficiency and safety aspects of hydrogen peroxide vapour and aerosolized hydrogen peroxide room disinfection systems.

PubMed

Fu, T Y; Gent, P; Kumar, V

2012-03-01

This was a head-to-head comparison of two hydrogen-peroxide-based room decontamination systems. To compare the efficacy, efficiency and safety of hydrogen peroxide vapour (HPV; Clarus R, Bioquell, Andover, U.K.) and aerosolized hydrogen peroxide (aHP; SR2, Sterinis, now supplied as Glosair, Advanced Sterilization Products (ASP), Johnson & Johnson Medical Ltd, Wokingham, U.K.) room disinfection systems. Efficacy was tested using 4- and 6-log Geobacillus stearothermophilus biological indicators (BIs) and in-house prepared test discs containing approximately 10(6) meticillin-resistant Staphylococcus aureus (MRSA), Clostridium difficile and Acinetobacter baumannii. Safety was assessed by detecting leakage of hydrogen peroxide using a hand-held detector. Efficiency was assessed by measuring the level of hydrogen peroxide using a hand-held sensor at three locations inside the room, 2 h after the start of the cycles. HPV generally achieved a 6-log reduction, whereas aHP generally achieved less than a 4-log reduction on the BIs and in-house prepared test discs. Uneven distribution was evident for the aHP system but not the HPV system. Hydrogen peroxide leakage during aHP cycles with the door unsealed, as per the manufacturer's operating manual, exceeded the short-term exposure limit (2 ppm) for more than 2 h. When the door was sealed with tape, as per the HPV system, hydrogen peroxide leakage was <1 ppm for both systems. The mean concentration of hydrogen peroxide in the room 2 h after the cycle started was 1.3 [standard deviation (SD) 0.4] ppm and 2.8 (SD 0.8) ppm for the four HPV and aHP cycles, respectively. None of the readings were <2 ppm for the aHP cycles. The HPV system was safer, faster and more effective for biological inactivation. Crown Copyright © 2012. Published by Elsevier Ltd. All rights reserved.

Amperometric hydrogen peroxide and glucose biosensor based on NiFe2/ordered mesoporous carbon nanocomposites.

PubMed

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.

High-speed graphene@Ag-MnO2 micromotors at low peroxide levels.

PubMed

Ye, Heng; Kang, Jian; Ma, Guofeng; Sun, Hongqi; Wang, Shaobin

2018-05-25

Platinum (Pt) free micro/nanomotors (MNMs) using a low content of fuels are highly desired for many applications. Herein, we demonstrate that cathodic electrofabrication can produce modified MnO 2 based microtubes and microrods as highly efficient MNMs in hydrogen peroxide (H 2 O 2 ) as low as 0.2%. The speed of graphene/Ag-MnO 2 micromotors could be smartly regulated using a surfactant and the maximum speed of an individual micromotor exceeds 1.3 mm s -1 in 0.5% H 2 O 2 . The propelling force and output power of the micromotors are 3.4 and 10 times as high as those of the best Pt-based micromotors reported. These Ag-MnO 2 based micromotors are envisioned to be a great promise for practical applications from biomedical delivery to environmental decontamination. Copyright © 2018 Elsevier Inc. All rights reserved.

Lanthanum(III)-catalyzed disproportionation of hydrogen peroxide: a heterogeneous generator of singlet molecular oxygen-1O2 (1Deltag)-in near-neutral aqueous and organic media for peroxidation of electron-rich substrates.

PubMed

Nardello, Véronique; Barbillat, Jacques; Marko, Jean; Witte, Peter T; Alsters, Paul L; Aubry, Jean-Marie

2003-01-20

The decomposition of hydrogen peroxide into singlet molecular oxygen-(1)O(2) ((1)Delta(g))-in the presence of lanthanum(iii) salts was studied by monitoring its characteristic IR luminescence at 1270 nm. The process was found to be heterogeneously catalyzed by La(III), provided that the heterogeneous catalyst is generated in situ. The yield of (1)O(2) generation was assessed as 45+/-5 % both in water and in methanol. The pH-dependence on the rate of (1)O(2) generation corresponds to a bell-shaped curve from pH 4.5 to 13 with a maximum around pH 8. The study of the influence of H(2)O(2) showed that the formation of (1)O(2) begins as soon as one equivalent of H(2)O(2) is introduced. It then increases drastically up to two equivalents and more smoothly above. Unlike all other metal salt catalyst systems known to date for H(2)O(2) disproportionation, this chemical source of (1)O(2) is able to generate (1)O(2) not only in basic media, but also under neutral and slightly acidic conditions. In addition, this La-based catalyst system has a very low tendency to induce unwanted oxygenating side reactions, such as epoxidation of alkenes. These two characteristics of the heterogeneous lanthanum catalyst system allow non-photochemical (i.e., "dark") singlet oxygenation of substrate classes that cannot be peroxidized successfully with conventional molybdate catalysts, such as allylic alcohols and alkenyl amines.

Do aerosols influence the diurnal variation of H2O2 in the atmosphere?

NASA Astrophysics Data System (ADS)

Liang, H.; Chen, Z.; Wu, Q.; Huang, D.; Zhao, Y.

2013-12-01

Hydrogen peroxide (H2O2) and organic peroxides are crucial reactive species that are involved in the cycling of HOx (OH and HO2) radicals and the formation of secondary inorganic and organic aerosols in the atmosphere. Despite the importance of peroxides, their formation and removal mechanisms with the coexistence of aerosols are as yet less well known. From June 10 to July 15 2013, summertime surface measurements for atmospheric peroxides were simultaneously obtained in urban Beijing (UB) and Gucheng (GC). The UB site is located in the northern downtown of Beijing city, while the GC site is a rural site located in the North China Plain and ~100 km southwest of Beijing. In both sites, the major peroxides were determined to be H2O2, methyl hydroperoxide (MHP), peroxyformic acid (PFA) and peroxyacetic acid (PAA). By comparing the concentrations of PFA and PAA in the gas phase and rainwater, for the first time, we estimated the Henry's law constant for PFA as ~210 M atm-1 at 298 K, a quarter of that for PAA. Interestingly, we observed different H2O2 profiles in the two sites as follows: (i) the average concentration of H2O2 in UB was 50% higher than that in GC; (ii) H2O2 in GC reached its peak concentration at around 15:30, whereas the peak concentration in UB appeared at as late as 21:00; and (iii) the daily variation of H2O2 in GC generally kept consistent with that of O3 and organic peroxides while it was not always the case in UB. These differences indicate a hitherto unrecognized storage-release mechanism for H2O2 in UB, that is, an extra sink in the noontime and an extra source in the early evening. The extra source of H2O2 would enhance the aerosol phase OH radical in the early evening by the Fenton reaction. A box model analysis shows that the impacts of aerosols were majorly responsible to this unrecognized mechanism, although NOx, regional transport and planet boundary layer height also contributed a minor part. Aerosols participated in the storage

Treatment of oily port wastewater effluents using the ultraviolet/hydrogen peroxide photodecomposition system.

PubMed

Siedlecka, Ewa Maria; Stepnowski, Piotr

2006-08-01

This paper presents the nonselective degradation of mechanically pretreated oily wastewater by hydrogen peroxide (H2O2) in the presence and absence of UV irradiation. The effect of chemical oxidation on wastewater biodegradability was also examined. The exclusive use of H2O2 photolyzed by daylight results in quite efficient degradation rates for the low peroxide concentrations used. Higher hydrogen peroxide concentrations inhibit degradation of organic contaminants in the wastewater. The degradation rates of all contaminants are relatively high with an advanced oxidation system (UV/H2O2), but degradation efficiencies are not distinguishably different when 20 or 45 minutes of UV irradiation is used. The excess of H2O2 used in the process can inhibit phenolic degradation and may lead to the formation of a new phenolic fraction. The biodegradability of port wastewater did not increase significantly following the application of the advanced oxidation process.

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

NASA Astrophysics Data System (ADS)

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

2017-07-01

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

Stress response and tolerance of Zea mays to CeO2 nanoparticles: cross talk among H2O2, heat shock protein, and lipid peroxidation.

PubMed

Zhao, Lijuan; Peng, Bo; Hernandez-Viezcas, Jose A; Rico, Cyren; Sun, Youping; Peralta-Videa, Jose R; Tang, Xiaolei; Niu, Genhua; Jin, Lixin; Varela-Ramirez, Armando; Zhang, Jian-ying; Gardea-Torresdey, Jorge L

2012-11-27

The rapid development of nanotechnology will inevitably release nanoparticles (NPs) into the environment with unidentified consequences. In addition, the potential toxicity of CeO(2) NPs to plants and the possible transfer into the food chain are still unknown. Corn plants (Zea mays) were germinated and grown in soil treated with CeO(2) NPs at 400 or 800 mg/kg. Stress-related parameters, such as H(2)O(2), catalase (CAT), and ascorbate peroxidase (APX) activity, heat shock protein 70 (HSP70), lipid peroxidation, cell death, and leaf gas exchange were analyzed at 10, 15, and 20 days post-germination. Confocal laser scanning microscopy was used to image H(2)O(2) distribution in corn leaves. Results showed that the CeO(2) NP treatments increased accumulation of H(2)O(2), up to day 15, in phloem, xylem, bundle sheath cells and epidermal cells of shoots. The CAT and APX activities were also increased in the corn shoot, concomitant with the H(2)O(2) levels. Both 400 and 800 mg/kg CeO(2) NPs triggered the up-regulation of the HSP70 in roots, indicating a systemic stress response. None of the CeO(2) NPs increased the level of thiobarbituric acid reacting substances, indicating that no lipid peroxidation occurred. CeO(2) NPs, at both concentrations, did not induce ion leakage in either roots or shoots, suggesting that membrane integrity was not compromised. Leaf net photosynthetic rate, transpiration, and stomatal conductance were not affected by CeO(2) NPs. Our results suggest that the CAT, APX, and HSP70 might help the plants defend against CeO(2) NP-induced oxidative injury and survive NP exposure.

Stress Response and Tolerance of Zea mays to CeO2 Nanoparticles: Cross Talk among H2O2, Heat Shock Protein and Lipid Peroxidation

PubMed Central

Zhao, Lijuan; Peng, Bo; Hernandez-Viezcas, Jose A.; Rico, Cyren; Sun, Youping; Peralta-Videa, Jose R.; Tang, Xiaolei; Niu, Genhua; Jin, Lixin; Varela-Ramirez, Armando; Zhang, Jian-ying; Gardea-Torresdey, Jorge L.

2014-01-01

The rapid development of nanotechnology will inevitably release nanoparticles (NPs) into the environment with unidentified consequences. In addition, the potential toxicity of CeO2 NPs to plants, and the possible transfer into the food chain, are still unknown. Corn plants (Zea mays) were germinated and grown in soil treated with CeO2 NPs at 400 or 800 mg/kg. Stress related parameters, such as: H2O2, catalase (CAT) and ascorbate peroxidase (APX) activity, heat shock protein 70 (HSP 70), lipid peroxidation, cell death and leaf gas exchange were analyzed at 10, 15, and 20 days post germination. Confocal laser scanning microscopy was used to image H2O2 distribution in corn leaves. Results showed that the CeO2 NP treatments increased accumulation of H2O2, up to day 15, in phloem, xylem, bundle sheath cells, and epidermal cells of shoots. The CAT and APX activities were also increased in the corn shoot, concomitant with the H2O2 levels. Both 400 and 800 mg/kg CeO2 NPs triggered the up regulation of the HSP 70 in roots, indicating a systemic stress response. None of the CeO2 NPs increased the level of thiobarbituric acid reacting substances, indicating that no lipid peroxidation occurred. CeO2 NPs, at both concentrations, did not induce ion leakage in either roots or shoots, suggesting membrane integrity was not compromised. Leaf net photosynthetic rate, transpiration, and stomatal conductance were not affected by CeO2 NPs. Our results suggest that the CAT, APX and HSP 70 might help the plants defend against CeO2 NPs induced oxidative injury and survive NP exposure. PMID:23050848

Hydrogen peroxide stabilization in one-dimensional flow columns.

PubMed

Schmidt, Jeremy T; Ahmad, Mushtaque; Teel, Amy L; Watts, Richard J

2011-09-25

Rapid hydrogen peroxide decomposition is the primary limitation of catalyzed H(2)O(2) propagations in situ chemical oxidation (CHP ISCO) remediation of the subsurface. Two stabilizers of hydrogen peroxide, citrate and phytate, were investigated for their effectiveness in one-dimensional columns of iron oxide-coated and manganese oxide-coated sand. Hydrogen peroxide (5%) with and without 25 mM citrate or phytate was applied to the columns and samples were collected at 8 ports spaced 13 cm apart. Citrate was not an effective stabilizer for hydrogen peroxide in iron-coated sand; however, phytate was highly effective, increasing hydrogen peroxide residuals two orders of magnitude over unstabilized hydrogen peroxide. Both citrate and phytate were effective stabilizers for manganese-coated sand, increasing hydrogen peroxide residuals by four-fold over unstabilized hydrogen peroxide. Phytate and citrate did not degrade and were not retarded in the sand columns; furthermore, the addition of the stabilizers increased column flow rates relative to unstabilized columns. These results demonstrate that citrate and phytate are effective stabilizers of hydrogen peroxide under the dynamic conditions of one-dimensional columns, and suggest that citrate and phytate can be added to hydrogen peroxide before injection to the subsurface as an effective means for increasing the radius of influence of CHP ISCO. Copyright © 2011. Published by Elsevier B.V.

Novel aqueous dual-channel aluminum-hydrogen peroxide battery

NASA Astrophysics Data System (ADS)

Marsh, Catherine; Licht, Stuart

1994-06-01

A dual-channel aluminum hydrogen peroxide battery is introduced with an open-circuit voltage of 1.9 volts, polarization losses of 0.9 mV cm(exp 2) mA(exp -1), and power densities of 1 W/cm(exp 2). Catholyte and anolyte cell compartments are separated by an Ir/Pd modified porous nickel cathode. Separation of catholyte and anolyte chambers prevents hydrogen peroxide poisoning of the aluminum anode. The battery is expressed by aluminum oxidation and aqueous solution phase hydrogen peroxide reduction for an overall battery discharge consisting of 2Al + 3H2O2 + 2OH(-) yields 2AlO2(-) + 4H2O E = 2.3 V. The search for electrical propulsion sources which fit the requirements for electrically powered vehicles has blurred the standard characteristics associated with electrochemical storage systems. Presently, electrochemical systems comprised of mechanically rechargeable primary batteries, secondary batteries, and fuel cells are candidates for electrochemical propulsion sources. While important advances in energy and power density continue for nonaqueous and molten electrolytes, aqueous electrolyte batteries often have an advantage in simplicity, conductivity, cost effectiveness, and environmental impact. Systems coupling aluminum anodes and aqueous electrolytes have been investigated. These systems include: aluminum/silver oxide, aluminum/manganese dioxide, aluminum air, aluminum/hydrogen peroxide aqueous batteries, and the recently introduced aluminum/ferricyanide and aluminum sulfur aqueous batteries. Conventional aqueous systems such as the nickel cadmium and lead-acid batteries are characterized by their relatively low energy densities and adverse environmental impact. Other systems have substantially higher theoretical energy capacities. While aluminum-silver oxide has demonstrated the highest steady-state power density, its high cost is an impediment for widespread utilization for electric propulsion.

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

PubMed

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 O 2 -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 O 2 , 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.

In-situ monitoring of H2O2 degradation by live cells using voltammetric detection in a lab-on-valve system.

PubMed

Lähdesmäki, Ilkka; Park, Young K; Carroll, Andrea D; Decuir, Michael; Ruzicka, Jaromir

2007-08-01

This paper describes a method for monitoring the degradation of hydrogen peroxide by cells immobilized on a beaded support. The detection is based on the voltammetric reduction of hydrogen peroxide on a mercury film working electrode, whilst combining the concept of sequential injection (SI) with the lab-on-valve (LOV) manifold allows the measurements to be carried out in real time and automatically, in well-defined conditions. The method is shown to be capable of simultaneously monitoring hydrogen peroxide in the 10-1000 microM range and oxygen in the 160-616 microM range. A correction algorithm has been used to ensure reliable H2O2 results in the presence of varying oxygen levels. The method has been successfully applied to monitoring the degradation of H2O2 by wild-type cells and by catalase-overexpressing mouse embryonic fibroblasts. Since the technique allows the monitoring of the initial response rate, it provides data not accessible by current methods that are end-point-based measurements.

2,4-Dinitrophenylhydrazine, redetermined at 120 K: a three-dimensional framework built from N-H...O, N-H...(O)2, N-H...pi(arene) and C-H...O hydrogen bonds.

PubMed

Wardell, James L; Low, John N; Glidewell, Christopher

2006-06-01

In the title compound, C6H6N4O4, the bond distances indicate significant bond fixation, consistent with charge-separated polar forms. The molecules are almost planar and there is an intramolecular N-H...O hydrogen bond. The molecules are linked into a complex three-dimensional framework structure by a combination of N-H...O, N-H...(O)2, N-H...pi(arene) and C-H...O hydrogen bonds.

Hydrogen peroxide and methylhydroperoxide variations in Houston urban air during May 2009

NASA Astrophysics Data System (ADS)

Golovko, J.; Rappenglueck, B.; Jobson, B. T.

2010-12-01

Formation and destruction of peroxides along with OH and ozone cycles plays a significant role in the oxidizing capacity of the troposphere. Measurements of hydrogen peroxide and methylhydroperoxide (MHP) were carried out as a part of the Study of Houston Atmospheric Radical Precursors (SHARP) campaign during late spring 2009. The purpose of this study was to investigate peroxides variations in Houston urban atmosphere and factors controlling their distribution. Diurnal variation of hydrogen peroxide show typical pattern with the broad maximum in the afternoon for the whole period of time, with an exception on May 19th when the second maximum was determined after the sunrise. Less abundant in the atmosphere and possibly originating from different sources methylhydroperoxide demonstrated similar diurnal pattern of elevated mixing ratios in the afternoon. Elevated values of hydrogen peroxide in Houston area are associated with warm, moderately humid air, while southerly winds from the Gulf of Mexico result in H2O2 mixing ratio decrease. Some selected VOCs were analyzed in order to evaluate possible sources for both peroxides. Meteorological conditions significantly control H2O2 mixing ratios, showing elevated values primarily related to easterly and to a lesser extent to southeasterly winds. Similar pattern with the significant role of the easterly winds was observed for VOCs and was more pronounced during nighttime, pointing into industrial sector (Houston Ship Channel) influence. Increased values of H2O2/MHP ratio are mostly associated with drier northerly and northeasterly air masses, pointing out different solubility and origin of H2O2 and MHP.

Effect of ethanol on hydrogen peroxide-induced AMPK phosphorylation.

PubMed

Liangpunsakul, Suthat; Wou, Sung-Eun; Zeng, Yan; Ross, Ruth A; Jayaram, Hiremagalur N; Crabb, David W

2008-12-01

AMP-activated protein kinase (AMPK) responds to oxidative stress. Previous work has shown that ethanol treatment of cultured hepatoma cells and of mice inhibited the activity of AMPK and reduced the amount of AMPK protein. Ethanol generates oxidative stress in the liver. Since AMPK is activated by reactive oxygen species, it seems paradoxical that ethanol would inhibit AMPK in the hepatoma cells. In an attempt to understand the mechanism whereby ethanol inhibits AMPK, we studied the effect of ethanol on AMPK activation by exogenous hydrogen peroxide. The effects of ethanol, hydrogen peroxide, and inhibitors of protein phosphatase 2A (PP2A) [either okadaic acid or PP2A small interference RNA (siRNA)] on AMPK phosphorylation and activity were examined in rat hepatoma cells (H4IIEC3) and HeLa cells. In H4IIEC3 cells, hydrogen peroxide (H(2)O(2), 1 mM) transiently increased the level of phospho-AMPK to 1.5-fold over control (P < 0.05). Similar findings were observed in HeLa cells, which do not express the upstream AMPK kinase, LKB1. H(2)O(2) markedly increased the phosphorylation of LKB1 in H4IIEC3 cells. Ethanol significantly inhibited the phosphorylation of PKC-zeta, LKB1, and AMPK caused by exposure to H(2)O(2). This inhibitory effect of ethanol required its metabolism. More importantly, the inhibitory effects of ethanol on H(2)O(2)-induced AMPK phosphorylation were attenuated by the presence of the PP2A inhibitor, okadaic acid, or PP2A siRNA. The inhibitory effect of ethanol on AMPK phosphorylation is exerted through the inhibition of PKC-zeta and LKB1 phosphorylation and the activation of PP2A.

Au/n-ZnO rectifying contact fabricated with hydrogen peroxide pretreatment

NASA Astrophysics Data System (ADS)

Gu, Q. L.; Cheung, C. K.; Ling, C. C.; Ng, A. M. C.; Djurišić, A. B.; Lu, L. W.; Chen, X. D.; Fung, S.; Beling, C. D.; Ong, H. C.

2008-05-01

Au contacts were deposited on n-type ZnO single crystals with and without hydrogen peroxide pretreatment for the ZnO substrate. The Au/ZnO contacts fabricated on substrates without H2O2 pretreatment were Ohmic and those with H2O2 pretreatment were rectifying. With an aim of fabricating a good quality Schottky contact, the rectifying property of the Au/ZnO contact was systemically investigated by varying the treatment temperature and duration. The best performing Schottky contact was found to have an ideality factor of 1.15 and a leakage current of ˜10-7 A cm-2. A multispectroscopic study, including scanning electron microscopy, positron annihilation spectroscopy, deep level transient spectroscopy, x-ray photoelectron spectroscopy, and photoluminescence, showed that the H2O2 treatment removed the OH impurity and created Zn-vacancy related defects hence decreasing the conductivity of the ZnO surface layer, a condition favorable for forming good Schottky contact. However, the H2O2 treatment also resulted in a deterioration of the surface morphology, leading to an increase in the Schottky contact ideality factor and leakage current in the case of nonoptimal treatment time and temperature.

Simultaneous high-resolution measurement of mitochondrial respiration and hydrogen peroxide production.

PubMed

Krumschnabel, Gerhard; Fontana-Ayoub, Mona; Sumbalova, Zuzana; Heidler, Juliana; Gauper, Kathrin; Fasching, Mario; Gnaiger, Erich

2015-01-01

Mitochondrial respiration is associated with the formation of reactive oxygen species, primarily in the form of superoxide (O2 (•-)) and particularly hydrogen peroxide (H2O2). Since H2O2 plays important roles in physiology and pathology, measurement of hydrogen peroxide has received considerable attention over many years. Here we describe how the well-established Amplex Red assay can be used to detect H2O2 production in combination with the simultaneous assessment of mitochondrial bioenergetics by high-resolution respirometry. Fundamental instrumental and methodological parameters were optimized for analysis of the effects of various substrate, uncoupler, and inhibitor titrations (SUIT) on respiration versus H2O2 production. The sensitivity of the H2O2 assay was strongly influenced by compounds contained in different mitochondrial respiration media, which also exerted significant effects on chemical background fluorescence changes. Near linearity of the fluorescence signal was restricted to narrow ranges of accumulating resorufin concentrations independent of the nature of mitochondrial respiration media. Finally, we show an application example using isolated mouse brain mitochondria as an experimental model for the simultaneous measurement of mitochondrial respiration and H2O2 production in SUIT protocols.

Chamomile Confers Protection against Hydrogen Peroxide-Induced Toxicity through Activation of Nrf2-Mediated Defense Response

PubMed Central

Bhaskaran, Natarajan; Srivastava, Janmejai K.; Shukla, Sanjeev; Gupta, Sanjay

2014-01-01

Oxidative stress plays an important role in the development of various human diseases. Aqueous chamomile extract is used as herbal medicine, in the form of tea, demonstrated to possess antiinflammatory and antioxidant properties. We demonstrate the cytoprotective effects of chamomile on hydrogen peroxide (H2O2)-induced cellular damage in macrophage RAW 264.7 cells. Pretreatment of cells with chamomile markedly attenuated H2O2-induced cell viability loss in a dose-dependent manner. The mechanisms by which chamomile-protected macrophages from oxidative stress was through the induction of several antioxidant enzymes including NAD (P)H:quinone oxidoreductase, superoxide dismutase, and catalase and increase nuclear accumulation of the transcription factor Nrf2 and its binding to antioxidant response elements. Furthermore, chamomile dose-dependently reduced H2O2-mediated increase in the intracellular levels of reactive oxygen species. Our results, for the first time, demonstrate that chamomile has protective effects against oxidative stress and might be beneficial to provide defense against cellular damage. PMID:22511316

Review of iron-free Fenton-like systems for activating H2O2 in advanced oxidation processes.

PubMed

Bokare, Alok D; Choi, Wonyong

2014-06-30

Iron-catalyzed hydrogen peroxide decomposition for in situ generation of hydroxyl radicals (HO(•)) has been extensively developed as advanced oxidation processes (AOPs) for environmental applications. A variety of catalytic iron species constituting metal salts (in Fe(2+) or Fe(3+) form), metal oxides (e.g., Fe2O3, Fe3O4), and zero-valent metal (Fe(0)) have been exploited for chemical (classical Fenton), photochemical (photo-Fenton) and electrochemical (electro-Fenton) degradation pathways. However, the requirement of strict acidic conditions to prevent iron precipitation still remains the bottleneck for iron-based AOPs. In this article, we present a thorough review of alternative non-iron Fenton catalysts and their reactivity towards hydrogen peroxide activation. Elements with multiple redox states (like chromium, cerium, copper, cobalt, manganese and ruthenium) all directly decompose H2O2 into HO(•) through conventional Fenton-like pathways. The in situ formation of H2O2 and decomposition into HO(•) can be also achieved using electron transfer mechanism in zero-valent aluminum/O2 system. Although these Fenton systems (except aluminum) work efficiently even at neutral pH, the H2O2 activation mechanism is very specific to the nature of the catalyst and critically depends on its composition. This review describes in detail the complex mechanisms and emphasizes on practical limitations influencing their environmental applications. Copyright © 2014 Elsevier B.V. All rights reserved.

H2O2 dynamics in the malaria parasite Plasmodium falciparum

PubMed Central

Rahbari, Mahsa; Bogeski, Ivan

2017-01-01

Hydrogen peroxide is an important antimicrobial agent but is also crucially involved in redox signaling and pathogen-host cell interactions. As a basis for systematically investigating intracellular H2O2 dynamics and regulation in living malaria parasites, we established the genetically encoded fluorescent H2O2 sensors roGFP2-Orp1 and HyPer-3 in Plasmodium falciparum. Both ratiometric redox probes as well as the pH control SypHer were expressed in the cytosol of blood-stage parasites. Both redox sensors showed reproducible sensitivity towards H2O2 in the lower micromolar range in vitro and in the parasites. Due to the pH sensitivity of HyPer-3, we used parasites expressing roGFP2-Orp1 for evaluation of short-, medium-, and long-term effects of antimalarial drugs on H2O2 levels and detoxification in Plasmodium. None of the quinolines or artemisinins tested had detectable direct effects on the H2O2 homeostasis at pharmacologically relevant concentrations. However, pre-treatment of the cells with antimalarial drugs or heat shock led to a higher tolerance towards exogenous H2O2. The systematic evaluation and comparison of the two genetically encoded cytosolic H2O2 probes in malaria parasites provides a basis for studying parasite-host cell interactions or drug effects with spatio-temporal resolution while preserving cell integrity. PMID:28369083

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

PubMed

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

2014-06-01

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

The human Krebs cycle 2-oxoglutarate dehydrogenase complex creates an additional source of superoxide/hydrogen peroxide from 2-oxoadipate as alternative substrate.

PubMed

Nemeria, Natalia S; Gerfen, Gary; Guevara, Elena; Nareddy, Pradeep Reddy; Szostak, Michal; Jordan, Frank

2017-07-01

Recently, we reported that the human 2-oxoglutarate dehydrogenase (hE1o) component of the 2-oxoglutarate dehydrogenase complex (OGDHc) could produce the reactive oxygen species superoxide and hydrogen peroxide (detected by chemical means) from its substrate 2-oxoglutarate (OG), most likely concurrently with one-electron oxidation by dioxygen of the thiamin diphosphate (ThDP)-derived enamine intermediate to a C2α-centered radical (detected by Electron Paramagnetic Resonance) [Nemeria et al., 2014 [17]; Ambrus et al. 2015 [18

Free standing graphene oxide film for hydrogen peroxide sensing

NASA Astrophysics Data System (ADS)

Ranjan, Pranay; Balakrishnan, Jayakumar; Thakur, Ajay D.

2018-05-01

We report hydrogen peroxide (H2O2)sensing using free standing graphene oxide thin films prepared using a cost effective scalable approach. Such sensors may find application in pharmaceutical and food processing industries.

Full-dimensional, high-level ab initio potential energy surfaces for H{sub 2}(H{sub 2}O) and H{sub 2}(H{sub 2}O){sub 2} with application to hydrogen clathrate hydrates

DOE Office of Scientific and Technical Information (OSTI.GOV)

Homayoon, Zahra; Conte, Riccardo; Qu, Chen

2015-08-28

New, full-dimensional potential energy surfaces (PESs), obtained using precise least-squares fitting of high-level electronic energy databases, are reported for intrinsic H{sub 2}(H{sub 2}O) two-body and H{sub 2}(H{sub 2}O){sub 2} three-body potentials. The database for H{sub 2}(H{sub 2}O) consists of approximately 44 000 energies at the coupled cluster singles and doubles plus perturbative triples (CCSD(T))-F12a/haQZ (aug-cc-pVQZ for O and cc-pVQZ for H) level of theory, while the database for the three-body interaction consists of more than 36 000 energies at the CCSD(T)-F12a/haTZ (aug-cc-pVTZ for O, cc-pVTZ for H) level of theory. Two precise potentials are based on the invariant-polynomial technique and are comparedmore » to computationally faster ones obtained via “purified” symmetrization. All fits use reduced permutational symmetry appropriate for these non-covalent interactions. These intrinsic potentials are employed together with existing ones for H{sub 2}, H{sub 2}O, and (H{sub 2}O){sub 2}, to obtain full PESs for H{sub 2}(H{sub 2}O) and H{sub 2}(H{sub 2}O){sub 2}. Properties of these full PESs are presented, including a diffusion Monte Carlo calculation of the zero-point energy and wavefunction, and dissociation energy of the H{sub 2}(H{sub 2}O) dimer. These PESs together with an existing one for water clusters are used in a many-body representation of the PES of hydrogen clathrate hydrates, illustrated for H{sub 2}@(H{sub 2}O){sub 20}. An analysis of this hydrate is presented, including the electronic dissociation energy to remove H{sub 2} from the calculated equilibrium structure.« less

Antioxidant/prooxidant effects of α-tocopherol, quercetin and isorhamnetin on linoleic acid peroxidation induced by Cu(II) and H2O2.

PubMed

Bakır, Temelkan; Sönmezoğlu, Inci; Imer, Filiz; Apak, Reşat

2014-03-01

The peroxidation of linoleic acid (LA) in the presence of copper(II) (Cu(II)) ions alone and with α-tocopherol (α-TocH) was investigated in aerated and incubated emulsions at 37 °C and pH 7. Additionally, the effects of quercetin (QR) and its O-methylated derivative, isorhamnetin (IR), as potential antioxidant protectors were studied in the (Cu(II) + TocH)-induced LA peroxidation system. Cu(II)-induced LA peroxidation followed pseudo-first-order kinetics with respect to primary (hydroperoxides) and secondary (aldehydes- and ketones-like) oxidation products, which were determined by ferric thiocyanate and thiobarbituric acid-reactive substances methods, respectively. As opposed to the concentration-dependent (at 0.6 and 10.0 µM) prooxidative action of α-TocH in the absence of QR and IR, the latter two compounds showed antioxidant effect over TocH. The peroxidation of LA in the presence of Cu(II)-H(2)O(2) combination alone and with TocH, QR and IR were also investigated in aerated and incubated emulsions, where the latter three compounds exhibited antioxidant effects.

Activation of Nrf2 by H2O2: de novo synthesis versus nuclear translocation.

PubMed

Covas, Gonçalo; Marinho, H Susana; Cyrne, Luísa; Antunes, Fernando

2013-01-01

The most common mechanism described for the activation of the transcription factor Nrf2 is based on the inhibition of its degradation in the cytosol followed by its translocation to the nucleus. Recently, Nrf2 de novo synthesis was proposed as an additional mechanism for the rapid upregulation of Nrf2 by hydrogen peroxide (H2O2). Here, we describe a detailed protocol, including solutions, pilot experiments, and experimental setups, which allows exploring the role of H2O2, delivered either as a bolus or as a steady state, in endogenous Nrf2 translocation and synthesis. We also show experimental data, illustrating that H2O2 effects on Nrf2 activation in HeLa cells are strongly dependent both on the H2O2 concentration and on the method of H2O2 delivery. The de novo synthesis of Nrf2 is triggered within 5min of exposure to low concentrations of H2O2, preceding Nrf2 translocation to the nucleus which is slower. Evidence of de novo synthesis of Nrf2 is observed only for low H2O2 steady-state concentrations, a condition that is prevalent in vivo. This study illustrates the applicability of the steady-state delivery of H2O2 to uncover subtle regulatory effects elicited by H2O2 in narrow concentration and time ranges. Copyright © 2013 Elsevier Inc. All rights reserved.

Silver-palladium catalysts for the direct synthesis of hydrogen peroxide

NASA Astrophysics Data System (ADS)

Khan, Zainab; Dummer, Nicholas F.; Edwards, Jennifer K.

2017-11-01

A series of bimetallic silver-palladium catalysts supported on titania were prepared by wet impregnation and assessed for the direct synthesis of hydrogen peroxide, and its subsequent side reactions. The addition of silver to a palladium catalyst was found to significantly decrease hydrogen peroxide productivity and hydrogenation, but crucially increase the rate of decomposition. The decomposition product, which is predominantly hydroxyl radicals, can be used to decrease bacterial colonies. The interaction between silver and palladium was characterized using scanning electron microscopy, X-ray diffraction, X-ray photoelectron spectroscopy (XPS) and temperature programmed reduction (TPR). The results of the TPR and XPS indicated the formation of a silver-palladium alloy. The optimal 1% Ag-4% Pd/TiO2 bimetallic catalyst was able to produce approximately 200 ppm of H2O2 in 30 min. The findings demonstrate that AgPd/TiO2 catalysts are active for the synthesis of hydrogen peroxide and its subsequent decomposition to reactive oxygen species. The catalysts are promising for use in wastewater treatment as they combine the disinfectant properties of silver, hydrogen peroxide production and subsequent decomposition. This article is part of a discussion meeting issue 'Providing sustainable catalytic solutions for a rapidly changing world'.

Dehydration of the Uranyl Peroxide Studtite, [UO 2(η 2-O 2)(H 2O) 2]·2H 2O, Affords a Drastic Change in the Electronic Structure: A Combined X-ray Spectroscopic and Theoretical Analysis

DOE Office of Scientific and Technical Information (OSTI.GOV)

Vitova, Tonya; Pidchenko, Ivan; Biswas, Saptarshi

The dehydration of studtite, [UO 2(2-O 2)(H 2O)2]·2H 2O, to metastudtite, [UO 2(2-O 2)(H 2O) 2], uranyl peroxide minerals that are major oxidative alteration phases of UO2 under conditions of geological storage, has been studied using X-ray photoelectron spectroscopy (XPS) and X-ray absorption spectroscopy. XPS of the U 4f region shows small but significant differences between studtite and metastudtite, with the 4f binding energy of studtite the highest reported for a uranyl mineral studied by this technique. Further information on the changes in the electronic structure was elucidated using U M4-edge High Energy Resolution XANES (HR-XANES) spectroscopy, which directly probesmore » f-orbital states. The transition from the 3d to the 5f* orbital is sensitive to variations of the U=Oaxial bond length and to changes in the bond covalency. We report evidences that the covalence in the uranyl fragment decreases upon dehydration. Photoluminescence spectroscopy at near liquid helium temperatures reveals significant spectral differences between the two materials, correlating with the X-ray spectroscopy results. A theoretical investigation has been conducted on the structures of both studtite and metastudtite and benchmarked to the HR-XANES spectra. These illustrate the sensitivity of the 3d to the 5f * transition towards U=Oaxial bond variation.« less

On the role of the termolecular reactions 2O2 + H2 → 2HO2 and 2O2 + H2 → H + HO2 + O2 in formation of the first radicals in hydrogen combustion: ab initio predictions of energy barriers.

PubMed

Monge-Palacios, M; Rafatijo, Homayoon

2017-01-18

We have investigated the role of termolecular reactions in the early chemistry of hydrogen combustion. We performed molecular chemical dynamics simulations using ReaxFF in LAMMPS to identify potential initial reactions for a 1 : 4 mixture of H 2  : O 2 in the NVT ensemble at density 276.3 kg m -3 and ∼3000 K (∼4000 atm) and ∼4000 K (∼5000 atm), and then characterized the saddle points for those reactions using ab initio methods: CCSD(T) = FC/cc-pVTZ//MP2/6-31G, CCSD(T) = FULL/aug-cc-pVTZ//CCSD = FC/cc-pVTZ and CASSCF MP2/6-31G//MP2/6-31G. The main initial reaction is H 2 + O 2 → H + HO 2 , frequently occurring in the presence of a second O 2 as a third body; that is, 2O 2 + H 2 → H + HO 2 + O 2 . The second most frequent reaction is 2O 2 + H 2 → 2HO 2 . We found three saddle points on the triplet PES of these termolecular reactions: one for 2O 2 + H 2 → H + HO 2 + O 2 and two for 2O 2 + H 2 → 2HO 2 . In the latter case, one has a symmetric structure consistent with simultaneous formation of two HO 2 and the other corresponds to a bimolecular reaction between O 2 and H 2 that is "interrupted" by a second O 2 before going to completion. The classical barrier height of the symmetric saddle point for 2O 2 + H 2 → 2HO 2 is 49.8 kcal mol -1 . The barrier to H 2 + O 2 → H + HO 2 is 58.9 kcal mol -1 . The termolecular reaction will be competitive with H 2 + O 2 → H + HO 2 only at sufficiently high pressures.

Neuroligin-3 protects retinal cells from H2O2-induced cell death via activation of Nrf2 signaling.

PubMed

Li, Xiu-Miao; Huang, Dan; Yu, Qing; Yang, Jian; Yao, Jin

2018-05-25

Intensified oxidative stress can cause severe damage to human retinal pigment epithelium (RPE) cells and retinal ganglion cells (RGCs). The potential effect of neuroligin-3 (NLGN3) against the process is studied here. Our results show that NLGN3 efficiently inhibited hydrogen peroxide (H 2 O 2 )-induced death and apoptosis in human RPE cells and RGCs. H 2 O 2 -induced reactive oxygen species (ROS) production, lipid peroxidation and DNA damage in retinal cells were alleviated by NLGN3. NLGN3 activated nuclear-factor-E2-related factor 2 (Nrf2) signaling, enabling Nrf2 protein stabilization, nuclear translocation and expression of key anti-oxidant enzymes (HO1, NOQ1 and GCLC) in RPE cells and RGCs. Further results demonstrate that NLGN3 activated Akt-mTORC1 signaling in retinal cells. Conversely, Akt-mTORC1 inhibitors (RAD001 and LY294002) reduced NLGN3-induced HO1, NOQ1 and GCLC mRNA expression. Significantly, Nrf2 silencing by targeted shRNAs reversed NLGN3-induced retinal cytoprotection against H 2 O 2 . We conclude that NLGN3 activates Nrf2 signaling to protect human retinal cells from H 2 O 2 . NLGN3 could be further tested as a valuable retinal protection agent. Copyright © 2018 Elsevier Inc. All rights reserved.

CO2 in solid para-hydrogen: spectral splitting and the CO2···(o-H2)n clusters.

PubMed

Du, Jun-He; Wan, Lei; Wu, Lei; Xu, Gang; Deng, Wen-Ping; Liu, An-Wen; Chen, Yang; Hu, Shui-Ming

2011-02-17

Complicated high-resolution spectral structures are often observed for molecules doped in solid molecular hydrogen. The structures can result from miscellaneous effects and are often interpreted differently in references. The spectrum of the ν(3) band of CO(2) in solid para-H(2) presents a model system which exhibits rich spectral structures. With the help of the potential energy simulation of the CO(2) molecule doped in para-hydrogen matrix, and extensive experiments with different CO(2) isotopologues and different ortho-hydrogen concentrations in the matrix, the spectral features observed in p-H(2) matrix are assigned to the CO(2)···(o-H(2))(n) clusters and also to energy level splitting that is due to different alignments of the doped CO(2) molecules in the matrix. The assignments are further supported by the dynamics analysis and also by the spectrum recorded with sample codoped with O(2) which serves as catalyst transferring o-H(2) to p-H(2) in the matrix at 4 K temperature. The observed spectral features of CO(2)/pH(2) can potentially be used as an alternative readout of the temperature and orthohydrogen concentration in the solid para-hydrogen.

Effects of Martian Surface Materials on the Thermal Decomposition of Hydrogen Peroxide

NASA Technical Reports Server (NTRS)

Archer, P. D., Jr.

2017-01-01

While hydrogen peroxide (H2O2) has been detected in the martian atmosphere, it has not been detected in surface materials. Since the Viking lander mission, we have sent instruments to Mars with the capability to detect H2O2. The Sample Analysis at Mars (SAM) instrument onboard the Curiosity Rover and Thermal and Evolved Gas Analyzer (TEGA) instrument on the Phoenix lander both detected water and oxygen releases from analyzed sediments but whether or not peroxide could be the source of these gases has not been investigated. We are investigating the possible presence of H2O2 in martian materials by analyzing Mars-relevant minerals that have been mixed with hydrogen peroxide using lab instruments configured as analogs to Mars mission instruments. The object of this research is to use lab instruments to find the effects of Mars analog minerals on hydrogen peroxide gas release temperatures, specifically gas releases of water and oxygen and also determine the effect of the peroxide on the minerals. Data that we get from the lab can then be compared to the data collected from Mars. The minerals hematite, siderite, San Carlos olivine, magnetite and nontronite were chosen as our Mars analog minerals. 20 mg of analog Mars minerals with 5µl of 50% H2O2, and were either run immediately or placed in a sealed tube for 2, 4, or 9 days to look for changes over time with two reps being done at each time step to determine repeatability. Each sample was heated from -60 degC to 500 degC at 20 degC/min and the evolved gases were monitored with a mass spectrometer. Each sample was also analyzed with an X-ray diffraction instrument to look for changes in mineralogy. Preliminary results show three potential outcomes: 1) peroxide has no effect on the sample (e.g., hematite), 2) the mineral is unaffected but catalyzes peroxide decomposition (magnetite, siderite), or 3) peroxide alters the mineral (pyrrhotite, San Carlos olivine).

Effects of Martian Surface Materials on the Thermal Decomposition of Hydrogen Peroxide

NASA Astrophysics Data System (ADS)

Dame, Rudger H.; Archer, Paul Douglas; Hogancamp, Joanna C.

2017-10-01

While hydrogen peroxide (H2O2) has been detected in the martian atmosphere, it has not been detected in surface materials. Since the Viking lander mission, we have sent instruments to Mars with the capability to detect H2O2. The Sample Analysis at Mars (SAM) instrument onboard the Curiosity Rover and Thermal and Evolved Gas Analyzer (TEGA) instrument on the Phoenix lander both detected water and oxygen releases from analyzed sediments but whether or not peroxide could be the source of these gases has not been investigated. We are investigating the possible presence of H2O2 in martian materials by analyzing Mars-relevant minerals that have been mixed with hydrogen peroxide using lab instruments configured as analogs to Mars mission instruments.The object of this research is to use lab instruments to find the effects of Mars analog minerals on hydrogen peroxide gas release temperatures, specifically gas releases of water and oxygen and also determine the effect of the peroxide on the minerals. Data that we get from the lab can then be compared to the data collected from Mars.The minerals hematite, siderite, San Carlos olivine, magnetite and nontronite were chosen as our Mars analog minerals. ~20 mg of analog Mars minerals with 5µl of 50% H2O2, and were either run immediately or placed in a sealed tube for 2, 4, or 9 days to look for changes over time with two reps being done at each time step to determine repeatability. Each sample was heated from -60 °C to 500 °C at 20 °C/min and the evolved gases were monitored with a mass spectrometer. Each sample was also analyzed with an X-ray diffraction instrument to look for changes in mineralogy.Preliminary results show three potential outcomes: 1) peroxide has no effect on the sample (e.g., hematite), 2) the mineral is unaffected but catalyzes peroxide decomposition (magnetite, siderite), or 3) peroxide alters the mineral (pyrrhotite, San Carlos olivine).

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

PubMed

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

2017-01-01

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

Fluorometric method for the determination of gas-phase hydrogen peroxide

NASA Technical Reports Server (NTRS)

Kok, Gregory L.; Lazrus, Allan L.

1986-01-01

The fluorometric gas-phase hydrogen peroxide procedure is based on the technique used by Lazrus et. al. for the determination of H2O2 in the liquid phase. The analytical method utilizes the reaction of H2O2 with horseradish peroxidase and p-hydroxphenylacetic acid (POPHA) to form the fluorescent dimer of POPHA. The analytical reaction responds stoichiometrically to both H2O2 and some organic hydroperoxides. To discriminate H2O2 from organic hydroperoxides, catalase is used to preferentially destroy H2O2. Using a dual-channel flow system the H2O2 concentration is determined by difference.

Degradation of crystal violet by an FeGAC/H2O2 process.

PubMed

Chen, Chiing-Chang; Chen, Wen-Ching; Chiou, Mei-Rung; Chen, Sheng-Wei; Chen, Yao Yin; Fan, Huan-Jung

2011-11-30

Because of the growing concern over highly contaminated crystal violet (CV) wastewater, an FeGAC/H(2)O(2) process was employed in this research to treat CV-contaminated wastewater. The experimental results indicated that the presence of iron oxide-coated granular activated carbon (FeGAC) greatly improved the oxidative ability of H(2)O(2) for the removal of CV. For instance, the removal efficiencies of H(2)O(2), GAC, FeGAC, GAC/H(2)O(2) and FeGAC/H(2)O(2) processes were 10%, 44%, 40%, 43% and 71%, respectively, at test conditions of pH 3 and 7.4mM H(2)O(2). FeGAC/H(2)O(2) combined both the advantages of FeGAC and H(2)O(2). FeGAC had a good CV adsorption ability and could effectively catalyze the hydrogen peroxide oxidation reaction. Factors (including pH, FeGAC dosage and H(2)O(2) dosage) affecting the removal of CV by FeGAC/H(2)O(2) were investigated in this research as well. In addition, the reaction intermediates were separated and identified using HPLC-ESI-MS. The N-demethylation step might be the main reaction pathway for the removal of CV. The reaction mechanisms for the process proposed in this research might be useful for future application of this technology to the removal of triphenylmethane (TPM) dyes. Copyright © 2011 Elsevier B.V. All rights reserved.

Laboratory IR Detection of H2O, CO2 in Ion-Irradiated Ices Relevant to Europa

NASA Technical Reports Server (NTRS)

Moore, Marla H.; Hudson, R. L.

1999-01-01

Hydrogen peroxide has been identified on Europa (Carlson et al. 1999) based in part on the 3.50 micron absorption feature observed in Galileo NIMS spectra. The observed feature was fitted with laboratory reflectance spectra of H2O + H2O2. Since condensed phase molecules on Europa (H2O, CO2, SO2, and H2O2) are bombarded with a significant flux of energetic particles (H(+), O(n+), S(n+) and e-), we examined the proton irradiation of H2O at 80 K and the conditions for the IR detection of H2O2 near 3.5 microns. Contrary to expectations, H2O2 was not detected if pure H2O ice was irradiated at 80 K. This was an unexpected result since, H2O2 was detected if pure H2O was irradiated at 18 K. We find, however, that if H2O ice contains either O2 or CO2 then H2O2 is detected after irradiation at 80 K (Moore and Hudson, 1999). The source of O2 for the H2O ice on Europa could come from surface interactions with the tenuous oxygen atmosphere, or from the bombardment of the surface by O(n+).

Hydrogen bonding in goldichite, KFe(SO4)2ṡ4H2O: structure refinement

NASA Astrophysics Data System (ADS)

Yang, Zhuming; Giester, Gerald

2018-02-01

The crystal structure of goldichite KFe(SO4)2ṡ4H2O was determined on a single crystal from the Baiyinchang copper deposit, Gansu, China. [ P121/ c1, a = 10.395(2), b = 10.475(2), c = 9.0875(18) Å, β = 101.65(3)°, V = 969.1(3) Å3, Z = 4]. All non-H atoms were refined with anisotropic displacement parameters and positions of H-atoms were determined by difference Fourier methods and refined from X-ray diffraction data. The crystal structure of goldichite consists of corrugated sheets parallel to the (100) plane by sharing corners between FeO6 octahedra and SO4 tetrahedra. The interstitial potassium atom exhibits a [KO7(H2O)2] nine-fold coordination, which shares edges to form a column parallel to the c-axis and to build a slab with the corrugated sheet. These slabs are linked in the [100] direction through a network of hydrogen bonds. Three types of hydrogen bonds involve links of slabs: Ow(3)-H(3B)···O(1), Ow(6)-H(6B)···O(11) and Ow(9)-H(9B)···O(11). The FTIR spectrum of goldichite shows a strong absorption between 3384 cm-1 and 3592 cm-1, which is in accordance with the O-H···O distances derived from structure data.

Sensitive Detection of Single-Cell Secreted H2O2 by Integrating a Microfluidic Droplet Sensor and Au Nanoclusters.

PubMed

Shen, Rui; Liu, Peipei; Zhang, Yiqiu; Yu, Zhao; Chen, Xuyue; Zhou, Lu; Nie, Baoqing; Żaczek, Anna; Chen, Jian; Liu, Jian

2018-04-03

As an important signaling molecule, hydrogen peroxide (H 2 O 2 ) secreted externally by the cells influences cell migration, immunity generation, and cellular communications. Herein, we have developed a microfluidic approach with droplets in combination with Au nanoclusters for the sensitive detection of H 2 O 2 secreted by a single cell. Isolated in the ultrasmall volume (4.2 nL) of a microdroplet, single-cell secreted H 2 O 2 can initiate dramatic fluorescence changes of horseradish peroxidase-Au nanoclusters. We have demonstrated an ultrahigh sensitivity (200-400 attomole H 2 O 2 directly measured from a single cell) with good specificity. It offers a useful research tool to study the cell-to-cell differences of H 2 O 2 secretion at the single-cell level.

[Determination of peracetic acid and hydrogen peroxide in a preparation].

PubMed

Bodiroga, Milanka; Ognjanović, Jasminka

2002-01-01

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).

Hydrogen peroxide-assisted synthesis of novel three-dimensional octagonal-like CuO nanostructures with enhanced visible-light-driven photocatalytic activity

NASA Astrophysics Data System (ADS)

Chen, Xiangyu; Chu, Deqing; Wang, Limin; Hu, Wenhui; Yang, Huifang; Sun, Jingjing; Zhu, Shaopeng; Wang, Guowei; Tao, Jian; Zhang, Songsong

2018-04-01

Novel three-dimensional octagonal-like CuO micro-/nanostructures with diameters ranging from 10 to 15 μm have been successfully prepared by hydrogen peroxide-assisted hydrothermal method and subsequent calcination. The product morphology can be changed by simply ordering the amount of hydrogen peroxide (H2O2). When the amounts of H2O2 is increased, the length of the corner portion is increased and the width is narrower. The obtained octagonal CuO nanostructures were evaluated for their ability for the degradation of hazardous organic contaminants in water under visible-light irradiation. Comparing with commercial CuO and other CuO products, the CuO octagonal nanostructures exhibit excellent performance for photocatalytic decomposition of RhB (Rhodamine B). It is well established that effective photocatalytic performance results from its unique 3D octagonal nanostructures. We believe that the present work will provide some ideas for further fabrication of other novel nanostructures and exploration of their applications.

Measurement of hydrogen peroxide and organic hydroperoxide concentrations during autumn in Beijing, China.

PubMed

Zhang, Qingyu; Liu, Jiaoyu; He, Youjiang; Yang, Jiaying; Gao, Jian; Liu, Houfeng; Tang, Wei; Chen, Yizhen; Fan, Wenhao; Chen, Xuan; Chai, Fahe; Hatakeyama, Shiro

2018-02-01

Gaseous peroxides play important roles in atmospheric chemistry. To understand the pathways of the formation and removal of peroxides, atmospheric peroxide concentrations and their controlling factors were measured from 7:00 to 20:00 in September, October, and November 2013 at a heavily trafficked residential site in Beijing, China, with average concentrations of hydrogen peroxide (H 2 O 2 ) and methyl hydroperoxide (MHP) at 0.55ppb and 0.063ppb, respectively. H 2 O 2 concentrations were higher in the afternoon and lower in the morning and evening, while MHP concentrations did not exhibit a regular diurnal pattern. Both H 2 O 2 and MHP concentrations increased at dusk in most cases. Both peroxides displayed monthly variations with higher concentrations in September. These results suggested that photochemical activity was the main controlling factor on variations of H 2 O 2 concentrations during the measurement period. Increasing concentrations of volatile organic compounds emitted by motor vehicles were important contributors to H 2 O 2 and MHP enrichment. High levels of H 2 O 2 and MHP concentrations which occurred during the measurement period probably resulted from the transport of a polluted air mass with high water vapor content passing over the Bohai Bay, China. Copyright © 2017. Published by Elsevier B.V.

Exploring the possibility to store the mixed oxygen-hydrogen cluster in clathrate hydrate in molar ratio 1:2 (O2+2H2).

PubMed

Qin, Yan; Du, Qi-Shi; Xie, Neng-Zhong; Li, Jian-Xiu; Huang, Ri-Bo

2017-05-01

An interesting possibility is explored: storing the mixture of oxygen and hydrogen in clathrate hydrate in molar ratio 1:2. The interaction energies between oxygen, hydrogen, and clathrate hydrate are calculated using high level quantum chemical methods. The useful conclusion points from this study are summarized as follows. (1) The interaction energies of oxygen-hydrogen mixed cluster are larger than the energies of pure hydrogen molecular cluster. (2) The affinity of oxygen molecules with water molecules is larger than that of the hydrogen molecules with water molecules. (3) The dimension of O 2 -2H 2 interaction structure is smaller than the dimension of CO 2 -2H 2 interaction structure. (4) The escaping energy of oxygen molecules from the hydrate cell is larger than that of the hydrogen molecules. (5) The high affinity of the oxygen molecules with both the water molecules and the hydrogen molecules may promote the stability of oxygen-hydrogen mixture in the clathrate hydrate. Therefore it is possible to store the mixed (O 2 +2H 2 ) cluster in clathrate hydrate. Copyright © 2017 Elsevier Inc. All rights reserved.

Hydrogen atom abstraction from aldehydes - OH + H2CO and O + H2CO

NASA Technical Reports Server (NTRS)

Dupuis, M.; Lester, W. A., Jr.

1984-01-01

The essential features of the potential energy surfaces governing hydrogen abstraction from formaldehyde by oxygen atom and hydroxyl radical have been characterized with ab inito multiconfiguration Hartree-Fock (MCHF) and configuration interaction (CI) wave functions. The results are consistent with a very small activation energy for the OH + H2CO reaction, and an activation energy of a few kcal/mol for the O + H2CO reaction. In the transition state structure of both systems, the attacking oxygen atom is nearly collinear with the attacked CH bond.

Hydrogen peroxide prevents vascular calcification induced ROS production by regulating Nrf-2 pathway.

PubMed

Zhang, Wensong; Li, Yi; Ding, Hanlu; Du, Yaqin; Wang, Li

2016-08-01

Although vascular calcification in end-stage renal disease (ESRD) represents a ubiquitous human health problem, effective therapies with limited side effects are still lacking, and the precise mechanisms are not fully understood. The Nrf-2/ARE pathway is a pivotal to regulate anti-oxidative responses in vascular calcification upon ESRD. Although Nrf-2 plays a crucial role in atherosclerosis, pulmonary fibrosis, and brain ischemia, the effect of Nrf-2 and oxidative stress on vascular calcification in ESRD patients is still unclear. The aim of this research was to study the protective role of hydrogen peroxide in vascular calcification and the mechanism of Nrf-2 and oxidative stress on vascular calcification. Here we used the rat vascular smooth muscle cell model of β-glycerophosphate-induced calcification resembling vascular calcification in ESRD to investigate the therapeutic effect of 0.01 mM hydrogen peroxide on vascular calcification and further explores the possible underlying mechanisms. Our current report shows the in vitro role of 0.01 mM hydrogen peroxide in protecting against intracellular ROS accumulation upon vascular calcification. Both hydrogen peroxide and sulforaphane pretreatment reduced ROS production, increased the expression of Nrf-2, and decreased the expression of Runx2 following calcification. Our study demonstrates that 0.01 mM hydrogen peroxide can effectively protect rat aortic vascular smooth muscle cells against oxidative stress by preventing vascular calcification induced ROS production through Nrf-2 pathway. These data might define an antioxidant role of hydrogen peroxide in vascular calcification upon ESRD.

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

PubMed

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

2018-06-14

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

Carbon dots-decorated multiwalled carbon nanotubes nanocomposites as a high-performance electrochemical sensor for detection of H2O2 in living cells.

PubMed

Bai, Jing; Sun, Chunhe; Jiang, Xiue

2016-07-01

A novel enzyme-free hydrogen peroxide sensor composed of carbon dots (CDs) and multi-walled carbon nanotubes (MWCNTs) was prepared. It was found that the carbon dots-decorated multi-walled carbon nanotubes nanocomposites (CDs/MWCNTs) modified glassy carbon (GC) electrode (CDs/MWCNTs/GCE) exhibited a significant synergistic electrocatalytic activity towards hydrogen peroxide reduction as compared to carbon dots or multi-walled carbon nanotubes alone, and the CDs/MWCNTs/GCE has shown a low detection limit as well as excellent stability, selectivity, and reproducibility. These remarkable analytical advantages enable the practical application of CDs/MWCNTs/GCE for the real-time tracking of hydrogen peroxide (H2O2) released from human cervical cancer cells with satisfactory results. The enhanced electrochemical activity can be assigned to the edge plane-like defective sites and lattice oxygen in the CDs/MWCNTs nanocomposites due to the small amount of decoration of carbon dots on the multi-walled carbon nanotubes. Based on a facile preparation method and with good electrochemical properties, the CDs/MWCNTs nanocomposites represent a new class of carbon electrode for electrochemical sensor applications. Graphical Abstract CDs/MWCNTs exhibited good electrocatalytic activity and stability to H2O2 reduction and can be used for real-time detection of H2O2 released from living cells.

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

EPA Science Inventory

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...

H2O2-responsive molecularly engineered polymer nanoparticles as ischemia/reperfusion-targeted nanotherapeutic agents

NASA Astrophysics Data System (ADS)

Lee, Dongwon; Bae, Soochan; Hong, Donghyun; Lim, Hyungsuk; Yoon, Joo Heung; Hwang, On; Park, Seunggyu; Ke, Qingen; Khang, Gilson; Kang, Peter M.

2013-07-01

The main culprit in the pathogenesis of ischemia/reperfusion (I/R) injury is the overproduction of reactive oxygen species (ROS). Hydrogen peroxide (H2O2), the most abundant form of ROS produced during I/R, causes inflammation, apoptosis and subsequent tissue damages. Here, we report H2O2-responsive antioxidant nanoparticles formulated from copolyoxalate containing vanillyl alcohol (VA) (PVAX) as a novel I/R-targeted nanotherapeutic agent. PVAX was designed to incorporate VA and H2O2-responsive peroxalate ester linkages covalently in its backbone. PVAX nanoparticles therefore degrade and release VA, which is able to reduce the generation of ROS, and exert anti-inflammatory and anti-apoptotic activity. In hind-limb I/R and liver I/R models in mice, PVAX nanoparticles specifically reacted with overproduced H2O2 and exerted highly potent anti-inflammatory and anti-apoptotic activities that reduced cellular damages. Therefore, PVAX nanoparticles have tremendous potential as nanotherapeutic agents for I/R injury and H2O2-associated diseases.

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

EPA Science Inventory

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

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

PubMed

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

2016-12-01

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

Quantitative structure-activity relationship for the oxidation of aromatic organic contaminants in water by TAML/H2O2.

PubMed

Su, Hanrui; Yu, Chunyang; Zhou, Yongfeng; Gong, Lidong; Li, Qilin; Alvarez, Pedro J J; Long, Mingce

2018-05-02

Tetra-amido macrocyclic ligand (TAML) activator is a functional analog of peroxidase enzymes, which activates hydrogen peroxide (H 2 O 2 ) to form high valence iron-oxo complexes that selectively degrade persistent aromatic organic contaminants (ACs) in water. Here, we develop quantitative structure-activity relationship (QSAR) models based on measured pseudo first-order kinetic rate coefficients (k obs ) of 29 ACs (e.g., phenols and pharmaceuticals) oxidized by TAML/H 2 O 2 at neutral and basic pH values to gain mechanistic insight on the selectivity and pH dependence of TAML/H 2 O 2 systems. These QSAR models infer that electron donating ability (E HOMO ) is the most important AC characteristic for TAML/H 2 O 2 oxidation, pointing to a rate-limiting single-electron transfer (SET) mechanism. Oxidation rates at pH 7 also depend on AC reactive indices such as f min - and qH + , which respectively represent propensity for electrophilic attack and the most positive net atomic charge on hydrogen atoms. At pH 10, TAML/H 2 O 2 is more reactive towards ACs with a lower hydrogen to carbon atoms ratio (#H:C), suggesting the significance of hydrogen atom abstraction. In addition, lnk obs of 14 monosubstituted phenols is negatively correlated with Hammett constants (σ) and exhibits similar sensitivity to substituent effects as horseradish peroxidase. Although accurately predicting degradation rates of specific ACs in complex wastewater matrices could be difficult, these QSAR models are statistically robust and help predict both relative degradability and reaction mechanism for TAML/H 2 O 2 -based treatment processes. Copyright © 2018 Elsevier Ltd. All rights reserved.

Hydroxy acetone and lactic acid synthesis from aqueous propylene glycol/hydrogen peroxide catalysis on Pd-black

DOE Office of Scientific and Technical Information (OSTI.GOV)

Disselkamp, Robert S.; Harris, Benjamin D.; Hart, Todd R.

2008-07-20

The production of polyol chemicals is of increasing interest as they are obtained from the catalytic processing of biological feedstock materials, which also is becoming more prevalent. A case in point is glycerol production, formed as a byproduct in biodiesel catalytic processing. Here we report the reaction of a simple 1,2-diol, propylene glycol, with hydrogen peroxide and a Pd-black catalyst under reflux conditions at 368 K. The experiments were performed by either co-addition of hydrogen peroxide with air sparging, or addition of hydrogen peroxide alone, each yielding hydroxy acetone (HA) and acetic acid (AA) products, with a lesser amount ofmore » lactic acid (LA) formed. Product conversion data at near neutral pH versus hydrogen peroxide equivalents added relative to substrate is presented. Hydrogen peroxide addition without air sparging at 5 equivalents resulted in 65% conversion with an HA:AA molar ratio of 2:1. Conversely, hydrogen peroxide addition with air sparging at only 0.75 equivalents resulted in 40% conversion with an HA:AA ratio of 3:1. From this it is concluded that although the product distribution in these chemistries is somewhat unchanged by air sparging, it is surprising that the amount of reactive oxygen is greatly enhanced with co-addition of O2/H2O2. Additional studies have revealed the amount of LA formed can be enhanced under acidic conditions (pH=1.5 compared to pH=8.5), such that 26% of total product formation is LA. Since hydrogen peroxide is an environmentally clean reagent and becoming more cost effective to use, this work may guide future applied investigations into polyol chemical syntheses.« less

ON-SITE APPLICABILITY OF HYDROGEN PEROXIDE PRODUCING MICROBIAL ELECTROCHEMICAL CELLS COUPLED WITH UV IN WASTEWATER DISINFECTION STUDY

EPA Science Inventory

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...

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

PubMed

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

2011-11-01

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

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

PubMed Central

Hertzberger, Rosanne; Arents, Jos; Dekker, Henk L.; Pridmore, R. David; Gysler, Christof; Kleerebezem, Michiel

2014-01-01

Hydrogen peroxide production is a well-known trait of many bacterial species associated with the human body. In the presence of oxygen, the probiotic lactic acid bacterium Lactobacillus johnsonii NCC 533 excretes up to 1 mM H2O2, inducing growth stagnation and cell death. Disruption of genes commonly assumed to be involved in H2O2 production (e.g., pyruvate oxidase, NADH oxidase, and lactate oxidase) did not affect this. Here we describe the purification of a novel NADH-dependent flavin reductase encoded by two highly similar genes (LJ_0548 and LJ_0549) that are conserved in lactobacilli belonging to the Lactobacillus acidophilus group. The genes are predicted to encode two 20-kDa proteins containing flavin mononucleotide (FMN) reductase conserved domains. Reductase activity requires FMN, flavin adenine dinucleotide (FAD), or riboflavin and is specific for NADH and not NADPH. The Km for FMN is 30 ± 8 μM, in accordance with its proposed in vivo role in H2O2 production. Deletion of the encoding genes in L. johnsonii led to a 40-fold reduction of hydrogen peroxide formation. H2O2 production in this mutant could only be restored by in trans complementation of both genes. Our work identifies a novel, conserved NADH-dependent flavin reductase that is prominently involved in H2O2 production in L. johnsonii. PMID:24487531

[Oxidative stress experimental model of rat with stria vascularis marginal cells injury induced by hydrogen peroxide in vitro].

PubMed

Li, Jun; Kong, Wei-jia; Zhao, Xue-yan; Hu, Yu-juan

2008-11-01

To set up the oxidative stress experimental model of rat cochlea with stria vascularis marginal cells injury induced by hydrogen peroxide in vitro. Cultured marginal cells of rat were treated by 200, 300, 400, 600 and 800 micromol/L hydrogen peroxide (H(2)O(2)) for 0.5, 1, 2, 4, 16 and 24 hours, respectively. Cell viability was assessed by the CCK-8 assay. The content of the lipid peroxidation production malondialdehyde (MDA) were detected in H(2)O(2) induced marginal cells injury with different concentration H(2)O(2). Apoptosis was assessed by flow cytometry by propidium sodium staining. The expression of the cleaved-caspase-3 was assessed by Western blot. Being exposed to H(2)O(2), marginal cells displayed nuclear pyknosis and margination, cytoplasmic condensation, cell shrinkage and formation of membrane and bounded apoptotic bodies. A time-dependent and dose-dependent decrease of cellular viability was detected with the treatment of H(2)O(2). Cellular maleic dialdehyde was generated in proportion to the concentration of H(2)O(2) at 2 hours and the number of apoptotic cells increased significantly (P < 0. 05). Western blot showed the expression of the cleaved-caspase-3 increased when 200 micromol/L, 300 micromol/L and 400 micromol/L H(2)O(2) treated cultured marginal cells. Thereafter the expression of the cleaved-caspase-3 decreased with 600 micromol/L H(2)O(2) and with 800 micromol/L H(2)O(2) the expression of cleaved-caspase-3 was weak. The findings indicated that the experimental model can be established successfully using cultured cells exposed to H(2)O(2) and activation of caspase-3 is associated with hydrogen peroxide induced rat marginal cells the oxidative stress injury.

Transcriptome Analysis of H2O2-Treated Wheat Seedlings Reveals a H2O2-Responsive Fatty Acid Desaturase Gene Participating in Powdery Mildew Resistance

PubMed Central

Tang, Lichuan; Zhao, Guangyao; Zhu, Mingzhu; Chu, Jinfang; Sun, Xiaohong; Wei, Bo; Zhang, Xiangqi; Jia, Jizeng; Mao, Long

2011-01-01

Hydrogen peroxide (H2O2) plays important roles in plant biotic and abiotic stress responses. However, the effect of H2O2 stress on the bread wheat transcriptome is still lacking. To investigate the cellular and metabolic responses triggered by H2O2, we performed an mRNA tag analysis of wheat seedlings under 10 mM H2O2 treatment for 6 hour in one powdery mildew (PM) resistant (PmA) and two susceptible (Cha and Han) lines. In total, 6,156, 6,875 and 3,276 transcripts were found to be differentially expressed in PmA, Han and Cha respectively. Among them, 260 genes exhibited consistent expression patterns in all three wheat lines and may represent a subset of basal H2O2 responsive genes that were associated with cell defense, signal transduction, photosynthesis, carbohydrate metabolism, lipid metabolism, redox homeostasis, and transport. Among genes specific to PmA, ‘transport’ activity was significantly enriched in Gene Ontology analysis. MapMan classification showed that, while both up- and down- regulations were observed for auxin, abscisic acid, and brassinolides signaling genes, the jasmonic acid and ethylene signaling pathway genes were all up-regulated, suggesting H2O2-enhanced JA/Et functions in PmA. To further study whether any of these genes were involved in wheat PM response, 19 H2O2-responsive putative defense related genes were assayed in wheat seedlings infected with Blumeria graminis f. sp. tritici (Bgt). Eight of these genes were found to be co-regulated by H2O2 and Bgt, among which a fatty acid desaturase gene TaFAD was then confirmed by virus induced gene silencing (VIGS) to be required for the PM resistance. Together, our data presents the first global picture of the wheat transcriptome under H2O2 stress and uncovers potential links between H2O2 and Bgt responses, hence providing important candidate genes for the PM resistance in wheat. PMID:22174904

Physical and chemical effects on crystalline H2O2 induced by 20 keV protons.

PubMed

Loeffler, M J; Baragiola, R A

2009-03-21

We present laboratory studies on radiation chemistry, sputtering, and amorphization of crystalline H(2)O(2) induced by 20 keV protons at 80 K. We used infrared spectroscopy to identify H(2)O, O(3), and possibly HO(3), measure the fluence dependence of the fraction of crystalline and amorphous H(2)O(2) and of the production of H(2)O and destruction of H(2)O(2). Furthermore, using complementary techniques, we observe that the sputtering yield depends on fluence due to the buildup of O(2) radiation products in the sample. In addition, we find that the effective cross sections for the destruction of hydrogen peroxide and the production of water are very high compared to radiation chemical processes in water even though the fluence dependence of amorphization is nearly the same for the two materials. This result is consistent with a model of fast cooling of a liquid track produced by each projectile ion rather than with the disorder produced by the formation of radiolytic products.

Light-activated regulation of cofilin dynamics using a photocaged hydrogen peroxide generator.

PubMed

Miller, Evan W; Taulet, Nicolas; Onak, Carl S; New, Elizabeth J; Lanselle, Julie K; Smelick, Gillian S; Chang, Christopher J

2010-12-08

Hydrogen peroxide (H2O2) can exert diverse signaling and stress responses within living systems depending on its spatial and temporal dynamics. Here we report a new small-molecule probe for producing H2O2 on demand upon photoactivation and its application for optical regulation of cofilin-actin rod formation in living cells. This chemical method offers many potential opportunities for dissecting biological roles for H2O2 as well as remote control of cell behavior via H2O2-mediated pathways.

Special hydrogen bonds observed in two monovalent metal carboxylate-phosphinates: {NaH(Phsbnd PO2sbnd C2H4sbnd COOH)2}∞ and {[KH(Phsbnd PO2sbnd C2H4sbnd COOH)2]·H2O}∞

NASA Astrophysics Data System (ADS)

Zhao, Cui-Cui; Zhang, Jian-Wei; Zhou, Zhong-Gao; Du, Zi-Yi

2013-02-01

The addition of strong base such as sodium hydroxide or potassium hydroxide to the aqueous solution of (2-carboxyethyl)(phenyl)phosphinic acid afforded two novel monovalent metal carboxylate-phosphinates, namely, {NaH(Phsbnd PO2sbnd C2H4sbnd COOH)2}∞ (1) and {[KH(Phsbnd PO2sbnd C2H4sbnd COOH)2]·H2O}∞ (2). They represent the first examples of phosphinate containing short, symmetric or almost symmetric O⋯H⋯O hydrogen bonds.

Urea Hydrogen Peroxide Reduces the Numbers of Lactobacilli, Nourishes Yeast, and Leaves No Residues in the Ethanol Fermentation

PubMed Central

Narendranath, N. V.; Thomas, K. C.; Ingledew, W. M.

2000-01-01

Urea hydrogen peroxide (UHP) at a concentration of 30 to 32 mmol/liter reduced the numbers of five Lactobacillus spp. (Lactobacillus plantarum, L. paracasei, Lactobacillus sp. strain 3, L. rhamnosus, and L. fermentum) from ∼107 to ∼102 CFU/ml in a 2-h preincubation at 30°C of normal-gravity wheat mash at ∼21 g of dissolved solids per ml containing normal levels of suspended grain particles. Fermentation was completed 36 h after inoculation of Saccharomyces cerevisiae in the presence of UHP, even when wheat mash was deliberately contaminated (infected) with L. paracasei at ∼107 CFU/ml. There were no significant differences in the maximum ethanol produced between treatments when urea hydrogen peroxide was used to kill the bacteria and controls (in which no bacteria were added). However, the presence of L. paracasei at ∼107 CFU/ml without added agent resulted in a 5.84% reduction in the maximum ethanol produced compared to the control. The bactericidal activity of UHP is greatly affected by the presence of particulate matter. In fact, only 2 mmol of urea hydrogen peroxide per liter was required for disinfection when mashes had little or no particulate matter present. No significant differences were observed in the decomposition of hydrogen peroxide in normal-gravity wheat mash at 30°C whether the bactericidal agent was added as H2O2 or as urea hydrogen peroxide. NADH peroxidase activity (involved in degrading H2O2) increased significantly (P = 0.05) in the presence of 0.75 mM hydrogen peroxide (sublethal level) in all five strains of lactobacilli tested but did not persist in cells regrown in the absence of H2O2. H2O2-resistant mutants were not expected or found when lethal levels of H2O2 or UHP were used. Contaminating lactobacilli can be effectively managed by UHP, a compound which when used at ca. 30 mmol/liter happens to provide near-optimum levels of assimilable nitrogen and oxygen that aid in vigorous fermentation performance by yeast. PMID:11010858

Tracking the energy flow in the hydrogen exchange reaction OH + H2O → H2O + OH.

PubMed

Zhu, Yongfa; Ping, Leilei; Bai, Mengna; Liu, Yang; Song, Hongwei; Li, Jun; Yang, Minghui

2018-05-09

The prototypical hydrogen exchange reaction OH + H2O → H2O + OH has attracted considerable interest due to its importance in a wide range of chemically active environments. In this work, an accurate global potential energy surface (PES) for the ground electronic state was developed based on ∼44 000 ab initio points at the level of UCCSD(T)-F12a/aug-cc-pVTZ. The PES was fitted using the fundamental invariant-neural network method with a root mean squared error of 4.37 meV. The mode specific dynamics was then studied by the quasi-classical trajectory method on the PES. Furthermore, the normal mode analysis approach was employed to calculate the final vibrational state distribution of the product H2O, in which a new scheme to acquire the Cartesian coordinates and momenta of each atom in the product molecule from the trajectories was proposed. It was found that, on one hand, excitation of either the symmetric stretching mode or the asymmetric stretching mode of the reactant H2O promotes the reaction more than the translational energy, which can be rationalized by the sudden vector projection model. On the other hand, the relatively higher efficacy of exciting the symmetric stretching mode than that of the asymmetric stretching mode is caused by the prevalence of the indirect mechanism at low collision energies and the stripping mechanism at high collision energies. In addition, the initial collision energy turns ineffectively into the vibrational energy of the products H2O and OH while a fraction of the energy transforms into the rotational energy of the product H2O. Fundamental excitation of the stretching modes of H2O results in the product H2O having the highest population in the fundamental state of the asymmetric stretching mode, followed by the ground state and the fundamental state of the symmetric stretching mode.

On-site applicability of hydrogen peroxide producing microbial electrochemical cells (MECs) coupled with UV in wastewater disinfection study

EPA Science Inventory

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...

Hydrogen peroxide inhibits Ca2+-dependent chloride secretion across colonic epithelial cells via distinct kinase signaling pathways and ion transport proteins

PubMed Central

Chappell, Alfred E.; Bunz, Michael; Smoll, Eric; Dong, Hui; Lytle, Christian; Barrett, Kim E.; McCole, Declan F.

2018-01-01

Reactive oxygen species (ROS) are key mediators in a number of inflammatory conditions, including inflammatory bowel disease (IBD). ROS, including hydrogen peroxide (H2O2), modulate intestinal epithelial ion transport and are believed to contribute to IBD-associated diarrhea. Intestinal crypt fluid secretion, driven by electrogenic Cl− secretion, hydrates and sterilizes the crypt, thus reducing bacterial adherence. Here, we show that pathophysiological concentrations of H2O2 inhibit Ca2+-dependent Cl− secretion across T84 colonic epithelial cells by elevating cytosolic Ca2+, which contributes to activation of two distinct signaling pathways. One involves recruitment of the Ca2+-responsive kinases, Src and Pyk-2, as well as extracellular signal-regulated kinase (ERK). A separate pathway recruits p38 MAP kinase and phosphoinositide 3-kinase (PI3-K) signaling. The ion transport response to Ca2+-dependent stimuli is mediated in part by K+ efflux through basolateral K+ channels and Cl− uptake by the Na+-K+-2Cl− cotransporter, NKCC1. We demonstrate that H2O2 inhibits Ca2+-dependent basolateral K+ efflux and also inhibits NKCC1 activity independently of inhibitory effects on apical Cl− conductance. Thus, we have demonstrated that H2O2 inhibits Ca2+-dependent Cl− secretion through multiple negative regulatory signaling pathways and inhibition of specific ion transporters. These findings increase our understanding of mechanisms by which inflammation disturbs intestinal epithelial function and contributes to intestinal pathophysiology.—Chappell, A. E., Bunz, M., Smoll, E., Dong, H., Lytle, C., Barrett, K. E., McCole, D. F. Hydrogen peroxide inhibits Ca2+-dependent chloride secretion across colonic epithelial cells via distinct kinase signaling pathways and ion transport proteins. FASEB J. 22, 000–000 (2008) PMID:18211955

H2O2 modulates the energetic metabolism of the cloud microbiome

NASA Astrophysics Data System (ADS)

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

2017-12-01

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

Arsenic oxidation by UV radiation combined with hydrogen peroxide.

PubMed

Sorlini, S; Gialdini, F; Stefan, M

2010-01-01

Arsenic is a widespread contaminant in the environment around the world. The most abundant species of arsenic in groundwater are arsenite [As(III)] and arsenate [As(V)]. Several arsenic removal processes can reach good removal yields only if arsenic is present as As(V). For this reason it is often necessary to proceed with a preliminary oxidation of As(III) to As(V) prior to the removal technology. Several studies have focused on arsenic oxidation with conventional reagents and advanced oxidation processes. In the present study the arsenic oxidation was evaluated using hydrogen peroxide, UV radiation and their combination in distilled and in real groundwater samples. Hydrogen peroxide and UV radiation alone are not effective at the arsenic oxidation. Good arsenic oxidation yields can be reached in presence of hydrogen peroxide combined with a high UV radiation dose (2,000 mJ/cm(2)). The quantum efficiencies for As(III) oxidation were calculated for both the UV photolysis and the UV/H(2)O(2) processes.

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

PubMed

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

2018-03-01

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

Omeprazole induces heme oxygenase-1 in fetal human pulmonary microvascular endothelial cells via hydrogen peroxide-independent Nrf2 signaling pathway

DOE Office of Scientific and Technical Information (OSTI.GOV)

Patel, Ananddeep; Zhang, Shaojie; Shrestha, Amrit

Omeprazole (OM) is an aryl hydrocarbon receptor (AhR) agonist and a proton pump inhibitor that is used to treat humans with gastric acid related disorders. Recently, we showed that OM induces NAD (P) H quinone oxidoreductase-1 (NQO1) via nuclear factor erythroid 2-related factor 2 (Nrf2)-dependent mechanism. Heme oxygenase-1 (HO-1) is another cytoprotective and antioxidant enzyme that is regulated by Nrf2. Whether OM induces HO-1 in fetal human pulmonary microvascular endothelial cells (HPMEC) is unknown. Therefore, we tested the hypothesis that OM will induce HO-1 expression via Nrf2 in HPMEC. OM induced HO-1 mRNA and protein expression in a dose-dependent manner.more » siRNA-mediated knockdown of AhR failed to abrogate, whereas knockdown of Nrf2 abrogated HO-1 induction by OM. To identify the underlying molecular mechanisms, we determined the effects of OM on cellular hydrogen peroxide (H{sub 2}O{sub 2}) levels since oxidative stress mediated by the latter is known to activate Nrf2. Interestingly, the concentration at which OM induced HO-1 also increased H{sub 2}O{sub 2} levels. Furthermore, H{sub 2}O{sub 2} independently augmented HO-1 expression. Although N-acetyl cysteine (NAC) significantly decreased H{sub 2}O{sub 2} levels in OM-treated cells, we observed that OM further increased HO-1 mRNA and protein expression in NAC-pretreated compared to vehicle-pretreated cells, suggesting that OM induces HO-1 via H{sub 2}O{sub 2}-independent mechanisms. In conclusion, we provide evidence that OM transcriptionally induces HO-1 via AhR - and H{sub 2}O{sub 2} - independent, but Nrf2 - dependent mechanisms. These results have important implications for human disorders where Nrf2 and HO-1 play a beneficial role. - Highlights: • Omeprazole induces HO-1 in human fetal lung cells. • AhR deficiency fails to abrogate omeprazole-mediated induction of HO-1. • Nrf2 knockdown abrogates omeprazole-mediated HO-1 induction in human lung cells. • Hydrogen peroxide depletion

Microchannel Reactor System Design & Demonstration For On-Site H2O2 Production by Controlled H2/O2 Reaction

DOE Office of Scientific and Technical Information (OSTI.GOV)

Adeniyi Lawal

We successfully demonstrated an innovative hydrogen peroxide (H2O2) production concept which involved the development of flame- and explosion-resistant microchannel reactor system for energy efficient, cost-saving, on-site H2O2 production. We designed, fabricated, evaluated, and optimized a laboratory-scale microchannel reactor system for controlled direct combination of H2 and O2 in all proportions including explosive regime, at a low pressure and a low temperature to produce about 1.5 wt% H2O2 as proposed. In the second phase of the program, as a prelude to full-scale commercialization, we demonstrated our H2O2 production approach by ‘numbering up’ the channels in a multi-channel microreactor-based pilot plant tomore » produce 1 kg/h of H2O2 at 1.5 wt% as demanded by end-users of the developed technology. To our knowledge, we are the first group to accomplish this significant milestone. We identified the reaction pathways that comprise the process, and implemented rigorous mechanistic kinetic studies to obtain the kinetics of the three main dominant reactions. We are not aware of any such comprehensive kinetic studies for the direct combination process, either in a microreactor or any other reactor system. We showed that the mass transfer parameter in our microreactor system is several orders of magnitude higher than what obtains in the macroreactor, attesting to the superior performance of microreactor. A one-dimensional reactor model incorporating the kinetics information enabled us to clarify certain important aspects of the chemistry of the direct combination process as detailed in section 5 of this report. Also, through mathematical modeling and simulation using sophisticated and robust commercial software packages, we were able to elucidate the hydrodynamics of the complex multiphase flows that take place in the microchannel. In conjunction with the kinetics information, we were able to validate the experimental data. If fully implemented across the

Field-rugged sensitive hydrogen peroxide sensor based on tunable diode laser absorption spectroscopy (TDLAS)

NASA Astrophysics Data System (ADS)

Frish, M. B.; Morency, J. R.; Laderer, M. C.; Wainner, R. T.; Parameswaran, K. R.; Kessler, W. J.; Druy, M. A.

2010-04-01

This paper reports the development and initial testing of a field-portable sensor for monitoring hydrogen peroxide (H2O2) and water (H2O) vapor concentrations during building decontamination after accidental or purposeful exposure to hazardous biological materials. During decontamination, a sterilization system fills ambient air with water and peroxide vapor to near-saturation. The peroxide concentration typically exceeds several hundred ppm for tens of minutes, and subsequently diminishes below 1 ppm. The H2O2/ H2O sensor is an adaptation of a portable gas-sensing platform based on Tunable Diode Laser Absorption Spectroscopy (TDLAS) technology. By capitalizing on its spectral resolution, the TDLAS analyzer isolates H2O2 and H2O spectral lines to measure both vapors using a single laser source. It offers a combination of sensitivity, specificity, fast response, dynamic range, linearity, ease of operation and calibration, ruggedness, and portability not available in alternative H2O2 detectors. The H2O2 range is approximately 0- 5,000 ppm. The autonomous and rugged instrument provides real-time data. It has been tested in a closed-loop liquid/vapor equilibrium apparatus and by comparison against electrochemical sensors.

Oxygen venous embolism after the use of hydrogen peroxide during lumbar discectomy.

PubMed

Despond, O; Fiset, P

1997-04-01

The knee-prone position is commonly used for patients undergoing spinal surgery. Venous air embolism in such a position may be produced by the negative venous pressure gradient between the ambient air and the venous plexuses of the spinous process. When hydrogen peroxide is used to cleanse the wound, oxygen is produced. We report a case of suspected oxygen venous embolism during lumbar discectomy in the knee-prone position after use of H2O2. Immediately after irrigation of a discectomy wound with H2O2, a dramatic decrease of the PETCO2, blood pressure and oxygen saturation coincident with ST segment elevation occurred suggesting a coronary gas embolism. Symptomatic treatment was initiated immediately and the patient recovered without any sequelae. Although hydrogen peroxide has an innocuous reputation, cases of accidental ingestion or massive gas embolism after wound irrigation leading to death have been reported. A review of the literature suggests that many of the clinical and physiopathological features of air and oxygen emboli are similar. For both, measures of prevention and treatment of complications are similar. We argue that the use of hydrogen peroxide should be avoided during procedures where the position of the patient (sitting, knee-prone) increases the risk of gas embolism and that hydrogen peroxide is a potentially dangerous solution.

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

NASA Astrophysics Data System (ADS)

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

2018-02-01

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

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

PubMed

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

2017-05-09

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

The hydrogen peroxide impact on larval settlement and metamorphosis of abalone Haliotis diversicolor supertexta

NASA Astrophysics Data System (ADS)

Zhang, Xiangjing; Yang, Zhihui; Cai, Zhonghua

2008-08-01

Abalone Haliotis diversicolor supertexta is an important economic mollusk. The settlement and metamorphosis are two critical stages during its development period, which has direct influence on abalone survival and production. The influence of reactive oxygen species (hydrogen peroxide) on abalone embryo and juvenile development were examined in this study. Larvae of Haliotis diversicolor supertexta were induced to settlement and metamorphose by exposure to seawater supplemented with hydrogen peroxide. They had the best performance at 800 μmol/L. The concentration of 1 000 μmol/L or higher was toxic to the larvae, as the larvae could settle down only at benthic diatom plates without complete metamorphosis. In addition, H2O2 adding time was critical to the larval performance. 24h after two-day post-fertilization was proved to be the optimal adding time. In this paper, two action mechanisms of hydrogen peroxide are discussed: (1) hydrogen peroxide has direct toxicity to ciliated cells, thus cause apoptosis; (2) hydrogen peroxide, as a product from catecholamines’ autoxidation process in vivo, can reverse this process to produce neuro-transmitters to induce abalone metamorphosis.

Confined NaAlH4 nanoparticles inside CeO2 hollow nanotubes towards enhanced hydrogen storage.

PubMed

Gao, Qili; Xia, Guanglin; Yu, Xuebin

2017-10-05

NaAlH 4 has been widely regarded as a potential hydrogen storage material due to its favorable thermodynamics and high energy density. The high activation energy barrier and high dehydrogenation temperature, however, significantly hinder its practical application. In this paper, CeO 2 hollow nanotubes (HNTs) prepared by a simple electrospinning technique are adopted as functional scaffolds to support NaAlH 4 nanoparticles (NPs) towards advanced hydrogen storage performance. The nanoconfined NaAlH 4 inside CeO 2 HNTs, synthesized via the infiltration of molten NaAlH 4 into the CeO 2 HNTs under high hydrogen pressure, exhibited significantly improved dehydrogenation properties compared with both bulk and ball-milled CeO 2 HNTs-catalyzed NaAlH 4 . The onset dehydrogenation temperature of the NaAlH 4 @CeO 2 composite was reduced to below 100 °C, with only one main dehydrogenation peak appearing at 130 °C, which is 120 °C and 50 °C lower than for its bulk counterpart and for the ball-milled CeO 2 HNTs-catalyzed NaAlH 4 , respectively. Moreover, ∼5.09 wt% hydrogen could be released within 30 min at 180 °C, while only 1.6 wt% hydrogen was desorbed from the ball-milled NaAlH 4 under the same conditions. This significant improvement is mainly attributed to the synergistic effects contributed by the CeO 2 HNTs, which could act as not only a structural scaffold to fabricate and confine the NaAlH 4 NPs, but also as an effective catalyst to enhance the hydrogen storage performance of NaAlH 4 .

Direct synthesis of hydrogen peroxide from plasma-water interactions

PubMed Central

Liu, Jiandi; He, Bangbang; Chen, Qiang; Li, Junshuai; Xiong, Qing; Yue, Guanghui; Zhang, Xianhui; Yang, Size; Liu, Hai; Liu, Qing Huo

2016-01-01

Hydrogen peroxide (H2O2) is usually considered to be an important reagent in green chemistry since water is the only by-product in H2O2 involved oxidation reactions. Early studies show that direct synthesis of H2O2 by plasma-water interactions is possible, while the factors affecting the H2O2 production in this method remain unclear. Herein, we present a study on the H2O2 synthesis by atmospheric pressure plasma-water interactions. The results indicate that the most important factors for the H2O2 production are the processes taking place at the plasma-water interface, including sputtering, electric field induced hydrated ion emission, and evaporation. The H2O2 production rate reaches ~1200 μmol/h when the liquid cathode is purified water or an aqueous solution of NaCl with an initial conductivity of 10500 μS cm−1. PMID:27917925

Power generation in fuel cells using liquid methanol and hydrogen peroxide

NASA Technical Reports Server (NTRS)

Narayanan, Sekharipuram R. (Inventor); Valdez, Thomas I. (Inventor); Chun, William (Inventor)

2002-01-01

The invention is directed to an encapsulated fuel cell including a methanol source that feeds liquid methanol (CH.sub.3 OH) to an anode. The anode is electrical communication with a load that provides electrical power. The fuel cell also includes a hydrogen peroxide source that feeds liquid hydrogen peroxide (H.sub.2 O.sub.2) to the cathode. The cathode is also in communication with the electrical load. The anode and cathode are in contact with and separated by a proton-conducting polymer electrolyte membrane.

Distance-dependent radiation chemistry: Oxidation versus hydrogenation of CO in electron-irradiated H2O/CO/H2O ices

DOE Office of Scientific and Technical Information (OSTI.GOV)

Petrik, Nikolay G.; Monckton, Rhiannon J.; Koehler, Sven

Electron-stimulated oxidation of CO in layered H2O/CO/H2O ices was investigated with infrared reflection-absorption spectroscopy (IRAS) as function of the distance of the CO layer from the water/vacuum interface. The results show that while both oxidation and reduction reactions occur within the irradiated water films, there are distinct regions where either oxidation or reduction reactions are dominant. At depths less than ~ 15 ML, CO oxidation dominates over the sequential hydrogenation of CO to methanol (CH3OH), and CO2 is the major product of CO oxidation, consistent with previous observations. At its highest yield, CO2 accounts for ~45% of all the reactedmore » CO. Another oxidation product is identified as the formate anion (HCO2-). In contrast, for CO buried more than ~ 35 ML below the water/vacuum interface, the CO-to-methanol conversion efficiency is close to 100%. Production of CO2 and formate are not observed for the more deeply buried CO layers, where hydrogenation dominates. Experiments with CO dosed on pre-irradiated ASW samples suggest that OH radicals are primarily responsible for the oxidation reactions. Possible mechanisms of CO oxidation, involving primary and secondary processes of water radiolysis at low temperature, are discussed. The observed distance-dependent radiation chemistry results from the higher mobility of hydrogen atoms that are created by the interaction of the 100 eV electrons with the water films. These hydrogen atoms, which are primarily created at or near the water/vacuum interface, can desorb from or diffuse into the water films, while the less-mobile OH radicals remain in the near-surface zone resulting in preferential oxidation reactions there. The diffusing hydrogen atoms are responsible for the hydrogenation reactions that are dominant for the more deeply buried CO layers.« less

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

NASA Astrophysics Data System (ADS)

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

2017-03-01

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

Herschel Survey of Galactic OH+, H2O+, and H3O+: Probing the Molecular Hydrogen Fraction and Cosmic-Ray Ionization Rate

NASA Astrophysics Data System (ADS)

Indriolo, Nick; Neufeld, D. A.; Gerin, M.; Schilke, P.; Benz, A. O.; Winkel, B.; Menten, K. M.; Chambers, E. T.; Black, John H.; Bruderer, S.; Falgarone, E.; Godard, B.; Goicoechea, J. R.; Gupta, H.; Lis, D. C.; Ossenkopf, V.; Persson, C. M.; Sonnentrucker, P.; van der Tak, F. F. S.; van Dishoeck, E. F.; Wolfire, Mark G.; Wyrowski, F.

2015-02-01

In diffuse interstellar clouds the chemistry that leads to the formation of the oxygen-bearing ions OH+, H2O+, and H3O+ begins with the ionization of atomic hydrogen by cosmic rays, and continues through subsequent hydrogen abstraction reactions involving H2. Given these reaction pathways, the observed abundances of these molecules are useful in constraining both the total cosmic-ray ionization rate of atomic hydrogen (ζH) and molecular hydrogen fraction (f_H_2). We present observations targeting transitions of OH+, H2O+, and H3O+ made with the Herschel Space Observatory along 20 Galactic sight lines toward bright submillimeter continuum sources. Both OH+ and H2O+ are detected in absorption in multiple velocity components along every sight line, but H3O+ is only detected along 7 sight lines. From the molecular abundances we compute f_H_2 in multiple distinct components along each line of sight, and find a Gaussian distribution with mean and standard deviation 0.042 ± 0.018. This confirms previous findings that OH+ and H2O+ primarily reside in gas with low H2 fractions. We also infer ζH throughout our sample, and find a lognormal distribution with mean log (ζH) = -15.75 (ζH = 1.78 × 10-16 s-1) and standard deviation 0.29 for gas within the Galactic disk, but outside of the Galactic center. This is in good agreement with the mean and distribution of cosmic-ray ionization rates previously inferred from H_3^+ observations. Ionization rates in the Galactic center tend to be 10-100 times larger than found in the Galactic disk, also in accord with prior studies. Herschel is an ESA space observatory with science instruments provided by European-led Principal Investigator consortia and with important participation from NASA.

Feruloylserotonin inhibits hydrogen peroxide-induced melanogenesis and apoptosis in B16F10 and SK-Mel-2 melanoma cells.

PubMed

Cho, Hyejoung; Kim, Okjoon; Lee, Younghee; Kang, Li-Jung; Nguyen, Cam Ngoc; Ishihara, Atsushi; Kim, Hye-Eun

2017-09-30

Feruloylserotonin (FS) is a major bioactive component of safflower seeds, with documented strong antibacterial, anti-inflammatory, and free radical scavenging activities. Reactive oxygen species (ROS) can strongly induce melanogenesis and cell apoptosis. The present study aimed to investigate the ability of FS in preventing hydrogen peroxide (H 2 O 2 )-induced melanogenesis and cell apoptosis. Melanogenesis and apoptotic cell death were induced by transient exposure to H 2 O 2 in B16F10 and SK-Mel-2 melanoma cells. FS significantly inhibited melanogenesis and cell death in both cell lines. FS inhibited H 2 O 2 -induced melanin production by down-regulating CREB/MITF/TYR signaling via inhibited intracellular cAMP accumulation. Additionally, FS induced extracellular regulated kinase activation, which led to the degradation of MITF and consequently decreased TYR expression and melanin production in H 2 O 2 -stimulated cells. Furthermore, FS inhibited H 2 O 2 -induced apoptotic cell death by maintaining mitochondrial membrane potential. Therefore, FS might have potential use for cosmetic whitening and as a therapeutic agent for hyperpigmentation disorder. Copyright © 2017 The Authors. Published by Elsevier Inc. All rights reserved.

Modeling the Syn-Disposition of Nitrogen Donors in Non-Heme Diiron Enzymes. Synthesis, Characterization, and Hydrogen Peroxide Reactivity of Diiron(III) Complexes with the Syn N-Donor Ligand H2BPG2DEV

PubMed Central

Friedle, Simone; Kodanko, Jeremy J.; Morys, Anna J.; Hayashi, Takahiro; Moënne-Loccoz, Pierre; Lippard, Stephen J.

2009-01-01

In order to model the syn disposition of histidine residues in carboxylate-bridged non-heme diiron enzymes, we prepared a new dinucleating ligand, H2BPG2DEV, that provides this geometric feature. The ligand incorporates biologically relevant carboxylate functionalities, which have not been explored as extensively as nitrogen-only analogs. Three novel oxo-bridged diiron(III) complexes [Fe2(μ-O)(H2O)2-(BPG2DEV)](ClO4)2 (6), [Fe2(μ-O)(μ-O CAriPrO)(BPG2DEV)](ClO4) (7), and [Fe2(μ-O)(μ-CO3)(BPG2DEV)] (8) were prepared. Single crystal X-ray structural characterization confirms that two pyridines are bound syn with respect to the Fe–Fe vector in these compounds. The carbonato-bridged complex 8 forms quantitatively from 6 in a rapid reaction with gaseous CO2 in organic solvents. A common maroon-colored intermediate (λmax = 490 nm; ε = 1500 M−1 cm−1) forms in reactions of 6, 7, or 8 with H2O2 and NEt3 in CH3CN/H2O solutions. Mass spectrometric analyses of this species, formed using 18O-labeled H2O2, indicate the presence of a peroxide ligand bound to the oxo-bridged diiron(III) center. The Mössbauer spectrum at 90 K of the EPR-silent intermediate exhibits a quadrupole doublet with δ. = 0.58 mm/s and ΔEQ = 0.58 mm/s. The isomer shift is typical for a peroxodiiron(III) species, but the quadrupole splitting parameter is unusually small compared to related complexes. These Mössbauer parameters are comparable to those observed for a peroxo intermediate formed in the reaction of reduced toluene/o-xylene monooxygenase hydroxylase (ToMOH) with dioxygen. Resonance Raman studies reveal an unusually low-energy O–O stretching mode in the peroxo intermediate that is consistent with a short diiron distance. Although peroxodiiron(III) intermediates generated from 6, 7, and 8 are poor O-atom transfer catalysts, they display highly efficient catalase activity, with turnover numbers up to 10,000. In contrast to hydrogen peroxide reactions of diiron(III) complexes that lack

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

Treesearch

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

1998-01-01

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

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

NASA Technical Reports Server (NTRS)

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

2004-01-01

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

Bi2O3 cocatalyst improving photocatalytic hydrogen evolution performance of TiO2

NASA Astrophysics Data System (ADS)

Xu, Difa; Hai, Yang; Zhang, Xiangchao; Zhang, Shiying; He, Rongan

2017-04-01

Photocatalytic hydrogen production using water splitting is of potential importance from the viewpoint of renewable energy development. Herein, Bi2O3-TiO2 composite photocatalysts presented as Bi-Bi2O3-anatase-rutile TiO2 multijunction were first fabricated by a simple impregnation-calcination method using Bi2O3 as H2-production cocatalysts. The obtained multijunction samples exhibit an obvious enhancement in photocatalytic H2 evolution activity in the presence of glycerol. The effect of Bi2O3 amount on H2-evolution activity of TiO2 was investigated and the optimal Bi2O3 content was found to be 0.89 mol%, achieving a H2-production rate of 920 μmol h-1, exceeding that of pure TiO2 by more than 73 times. The enhanced mechanism of photocatalytic H2-evolution activity is proposed. This study will provide new insight into the design and fabrication of TiO2-based hydrogen-production photocatalysts using low-cost Bi2O3 as cocatalyst.

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

NASA Astrophysics Data System (ADS)

Milawarni; Nurlaili; Sariyadi

2018-05-01

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

3-Methyl-7-(2-thienyl)pyrido[2,3-d]pyrimidine-2,4(1H,3H)-dione: pi-stacked bilayers built from N-H...O, C-H...O and C-H...pi hydrogen bonds.

PubMed

Trilleras, Jorge; Quiroga, Jairo; Cobo, Justo; Glidewell, Christopher

2009-06-01

In the title compound, C(12)H(9)N(3)O(2)S, the thienyl substituent is disordered over two sets of sites with occupancies of 0.749 (3) and 0.251 (3). A combination of N-H...O, C-H...O and C-H...pi hydrogen bonds links the molecules into bilayers and these bilayers are themselves linked into a continuous structure by pi-pi stacking interactions.

Hydrogen Peroxide, Signaling in Disguise during Metal Phytotoxicity

PubMed Central

Cuypers, Ann; Hendrix, Sophie; Amaral dos Reis, Rafaela; De Smet, Stefanie; Deckers, Jana; Gielen, Heidi; Jozefczak, Marijke; Loix, Christophe; Vercampt, Hanne; Vangronsveld, Jaco; Keunen, Els

2016-01-01

Plants exposed to excess metals are challenged by an increased generation of reactive oxygen species (ROS) such as superoxide (O2•-), hydrogen peroxide (H2O2) and the hydroxyl radical (•OH). The mechanisms underlying this oxidative challenge are often dependent on metal-specific properties and might play a role in stress perception, signaling and acclimation. Although ROS were initially considered as toxic compounds causing damage to various cellular structures, their role as signaling molecules became a topic of intense research over the last decade. Hydrogen peroxide in particular is important in signaling because of its relatively low toxicity, long lifespan and its ability to cross cellular membranes. The delicate balance between its production and scavenging by a plethora of enzymatic and metabolic antioxidants is crucial in the onset of diverse signaling cascades that finally lead to plant acclimation to metal stress. In this review, our current knowledge on the dual role of ROS in metal-exposed plants is presented. Evidence for a relationship between H2O2 and plant metal tolerance is provided. Furthermore, emphasis is put on recent advances in understanding cellular damage and downstream signaling responses as a result of metal-induced H2O2 production. Finally, special attention is paid to the interaction between H2O2 and other signaling components such as transcription factors, mitogen-activated protein kinases, phytohormones and regulating systems (e.g. microRNAs). These responses potentially underlie metal-induced senescence in plants. Elucidating the signaling network activated during metal stress is a pivotal step to make progress in applied technologies like phytoremediation of polluted soils. PMID:27199999

Hydrogen Sensor Based on Pd/GeO{sub 2} Using a Low Cost Electrochemical Deposition

DOE Office of Scientific and Technical Information (OSTI.GOV)

Jawad, M. J.; Hashim, M. R.; Ali, N. K.

2011-05-25

This work reports on a synthesis of sub micron germanium dioxide (GeO{sub 2}) on porous silicon (PS) by electrochemical deposition. n-type Si (100) wafer was used to fabricate (PS) using conventional method of electrochemical etching in HF based solution. A GeCl{sub 4} was directly hydrolyzed by hydrogen peroxide to produce pure GeO{sub 2}, and then electrochemically deposited on PS. Followed by palladium (Pd) contact on GeO{sub 2} /PS was achieved by using RF sputtering technique. The grown GeO{sub 2} crystals were characterized using SEM and EDX. I-V characteristics of Pd/ GeO{sub 2} were recorded before and after hydrogen gas exposuremore » as well as with different H{sub 2} concentrations and different applied temperatures. The sensitivity of Pd/ GeO{sub 2} also has been investigated it could be seen to increase significantly with increased hydrogen concentration while it decreased with increase temperature.« less

Effect of exogenous hydrogen peroxide on iodide transport and iodine organification in FRTL-5 rat thyroid cells.

PubMed

Chen, G; Pekary, A E; Sugawara, M; Hershman, J M

1993-07-01

Hydrogen peroxide plays an important role in the regulation of iodination and thyroid hormone formation. In the present study, the effect of exogenous H2O2 on 125I transport and organification was investigated in FRTL-5 rat thyroid cells. Less than 20 passages after subcloning, cells in 24-well plates (6 x 10(4) cells/well) were maintained in a thyrotropin (TSH)-containing medium (6H) for 3 days. A TSH-free medium (5H) was then used for the next 7 days. A 1-h exposure to H2O2 stimulated 125I transport and 125I organification at 0.1-0.5 mmol/l H2O2 and had a toxic effect on FRTL-5 cell at 5 mmol/l. Hydrogen peroxide (0.5 mmol/l) augmented the iodide transport and iodine organification induced by TSH (333 U/l) by two- and threefold, respectively. The biphasic effect of H2O2 was blocked totally by 5-200 micrograms/l of catalase. Catalase by itself did not influence TSH-mediated 125I transport and 125I organification. Hydrogen peroxide (0.5 mmol/l) added to cells in 5H medium increased Na+K(+)-ATPase activity twofold. Ouabain (1 mmol/l), an inhibitor of Na+K(+)-ATPase, completely inhibited the twofold increase in 125I transport induced by 0.5 mmol/l H2O2 but only inhibited H2O2-induced 125I organification by 28%. Methimazole (1 mmol/l), an inhibitor of thyroid peroxidase, had no effect on H2O2-mediated 125I transport but totally blocked the fivefold rise in 125I organification induced by 0.5 mmol/l H2O2. The effect of H2O2 on intracellular cyclic adenosine monophosphate (cAMP) levels also was studied.(ABSTRACT TRUNCATED AT 250 WORDS)

Transient generation of hydrogen peroxide is responsible for carcinostatic effects of hydrogen combined with platinum nanocolloid, together with increases intracellular ROS, DNA cleavages, and proportion of G2/M-phase.

PubMed

Saitoh, Yasukazu; Ikeshima, Minoru; Kawasaki, Naho; Masumoto, Aoi; Miwa, Nobuhiko

2016-01-01

In our previous study, we demonstrated that combined treatment with hydrogen (H2) and platinum nanocolloid (Pt-nc) exerted markedly antiproliferative effects on cancer cells compared with each treatment alone. However, because the related mechanisms remain unclear, we investigated carcinostatic mechanisms of the combined treatment with H2 + Pt-nc. Significant suppression of cell proliferation was confirmed at 52 h following combined treatment, and the similar effect was also observed by the 30- or 40-min transient treatment with H2 + Pt-nc. The transient treatments led to changes in cell size and morphology, loss of microvilli, and apoptosis-like cell death at 120 h after treatment. Moreover, transient combined treatment with H2 + Pt-nc induced cell-cycle arrest, as reflected by decreased proportions of G1-phase cells and accumulation of G2/M-phase cells. In contrast, intracellular peroxide levels were temporarily and significantly increased immediately after H2 + Pt-nc treatment but not after treatment with H2 or Pt-nc alone. Additionally, combined treatment-induced carcinostatic effects were significantly diminished in the presence of catalase, and marked hydrogen peroxide (H2O2) generation was confirmed after mixing Pt-nc into cell culture media containing a high concentration of H2. These changes are in agreement with the results that carcinostatic effects were induced after only 40 min of treatment with H2 + Pt-nc. Thus, transient and marked generation of H2O2 is responsible for the carcinostatic effects of combined treatment with H2 + Pt-nc.

Real-time monitoring of H2O2 release from single cells using nanoporous gold microelectrodes decorated with platinum nanoparticles.

PubMed

Xiao, Chong; Liu, Yan-Ling; Xu, Jia-Quan; Lv, Song-Wei; Guo, Shan; Huang, Wei-Hua

2015-06-07

Here, we report a self-supported nanoporous gold microelectrode decorated with well-dispersed and tiny platinum nanoparticles as an electrochemical nonenzymatic hydrogen peroxide biosensor. Nanoporous gold was fabricated by electrochemical alloying/dealloying and then small-sized platinum nanoparticles were electrodeposited uniformly on them. This novel hybrid nanostructure endows the sensor with high sensitivity and selectivity towards the reduction of hydrogen peroxide with a low detection limit of 0.3 nM. The sensor has been successfully applied for the measurement of H2O2 release from a single isolated human breast cancer cell, demonstrating its great potential for further physiological and pathological applications.

Using in vivo oxidation status of one- and two-component redox relays to determine H2O2 levels linked to signaling and toxicity.

PubMed

Domènech, Alba; Ayté, José; Antunes, Fernando; Hidalgo, Elena

2018-06-01

Hydrogen peroxide (H 2 O 2 ) is generated as a by-product of metabolic reactions during oxygen use by aerobic organisms, and can be toxic or participate in signaling processes. Cells, therefore, need to be able to sense and respond to H 2 O 2 in an appropriate manner. This is often accomplished through thiol switches: Cysteine residues in proteins that can act as sensors, and which are both scarce and finely tuned. Bacteria and eukaryotes use different types of such sensors-either a one-component (OxyR) or two-component (Pap1-Tpx1) redox relay, respectively. However, the biological significance of these two different signaling modes is not fully understood, and the concentrations and peroxides driving those types of redox cascades have not been determined, nor the intracellular H 2 O 2 levels linked to toxicity. Here we elucidate the characteristics, rates, and dynamic ranges of both systems. By comparing the activation of both systems in fission yeast, and applying mathematical equations to the experimental data, we estimate the toxic threshold of intracellular H 2 O 2 able to halt aerobic growth, and the temporal gradients of extracellular to intracellular peroxides. By calculating both the oxidation rates of OxyR and Tpx1 by peroxides, and their reduction rates by the cellular redoxin systems, we propose that, while Tpx1 is a sensor and an efficient H 2 O 2 scavenger because it displays fast oxidation and reduction rates, OxyR is strictly a H 2 O 2 sensor, since its reduction kinetics are significantly slower than its oxidation by peroxides, and therefore, it remains oxidized long enough to execute its transcriptional role. We also show that these two paradigmatic H 2 O 2 -sensing models are biologically similar at pre-toxic peroxide levels, but display strikingly different activation behaviors at toxic doses. Both Tpx1 and OxyR contain thiol switches, with very high reactivity towards peroxides. Nevertheless, the fast reduction of Tpx1 defines it as a scavenger

Hydrogen peroxide (H/sub 2/O/sub 2/) stimulates the active transport of 5-hydroxytryptamine (5-HT) into platelets

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bosin, T.R.

1986-03-01

Platelets function in a variety of physiological and pathological processes which may be altered by oxidant injury. One such process is the active transport 5-HT, which is an important mechanism in the control of circulating 5-HT levels. Exposure of mouse platelets (10/sup 8//ml) to H/sub 2/O/sub 2/ caused a time-dependent and dose-dependent increase in 5-HT (10/sup -7/M) uptake. The uptake 4 and 10 min following H/sub 2/O/sub 2/ (50 ..mu..M) was 228% and 145% of control values, respectively. Fluoxetine (10/sup -6/M) blocked all 5-HT uptake and catalase (1500 U/ml) blocked the H/sub 2/O/sub 2/-stimulated uptake. Enzymatically produced H/sub 2/O/sub 2/more » (glucose/glucose oxidase) and xanthine (X)/xanthine oxidase (XO) generated oxygen radicals produced quantitatively and qualitatively similar results. The stimulatory response of platelets to X/XO generated oxidants was unaffected by superoxide dismutase (250 U/ml) but, was inhibited using heat-denatured XO, allopurinol (0.5 mM) and catalase; fluoxetine inhibited all 5-HT uptake. Platelets exposed to X/XO in the presence of chelated (EDTA, 100 ..mu..M) or unchelated FeSO/sub 4/, FeNH/sub 4/(SO/sub 4/)/sub 2/ or CuCl (50 ..mu..M) did not have altered 5-HT uptake. These data indicate that brief exposure of platelets to physiological levels of H/sub 2/O/sub 2/ results in marked, reversible stimulation of active 5-HT uptake which may represent a homeostatic defense mechanism when H/sub 2/O/sub 2/ is elevated in the platelet microenvironment.« less

Role of chemical interaction between MgH2 and TiO2 additive on the hydrogen storage behavior of MgH2

NASA Astrophysics Data System (ADS)

Pukazhselvan, D.; Nasani, Narendar; Sandhya, K. S.; Singh, Budhendra; Bdikin, Igor; Koga, Nobuaki; Fagg, Duncan Paul

2017-10-01

The present study explores how the additive titania chemically reacts with magnesium hydride and influences the dehydrogenation of MgH2. Quantitative X - ray diffraction study of ball milled MgH2 + xTiO2 (x = 0.25, 0.33, 0.5 and 1) suggests that Ti substituted MgO is the main reaction product in all the product powders. Convincing evidence is obtained to conclude that Ti dissolution in MgO makes a dramatic behavioral change to MgO; passive MgO turns as an active in-built catalyst. The analysis correlating the dehydrogenation kinetics, composition of in-situ catalyst and sample durability suggests that effectiveness of Ti substituted MgO (MgxTiyOx+y) as a catalyst for MgH2 depends on the concentration of Ti in MgxTiyOx+y rock salt. These observations are immensely helpful for understanding the hydrogen desorption mechanism of metal oxide additives loaded MgH2 system.

Effects of hydrogen peroxide feeding strategies on the photochemical degradation of polyvinyl alcohol.

PubMed

Hamad, Dina; Dhib, Ramdhane; Mehrvar, Mehrab

2016-11-01

The performance of batch and fed-batch photoreactors with that of continuous photoreactor for the treatment of aqueous polyvinyl alcohol (PVA) solutions is compared. Hydrogen peroxide feeding strategies, residence time, and [H2O2]/[PVA] mass ratio are examined for their impacts on the molecular weight distribution (MWD) of PVA and the total organic carbon (TOC) removal. The results prove that a continuous addition of H2O2 during the degradation reaction ensures the utilization of the produced radicals to minimize the oxidant consumption and maximize the TOC removal and the PVA degradation in a short irradiation time. Also, the MWD of PVA is found to be bimodal and shifted towards lower molecular weights with small shoulder peak indicating a progressive disappearance of the higher molecular weight fractions that is in accordance with the random chains scission mechanism. Besides, the hydrogen peroxide feeding strategies are found to have a great effect on the reduction in H2O2 residuals in the effluent.

Detection of hydrogen peroxide based on long-path absorption spectroscopy using a CW EC-QCL

NASA Astrophysics Data System (ADS)

Sanchez, N. P.; Yu, Y.; Dong, L.; Griffin, R.; Tittel, F. K.

2016-02-01

A sensor system based on a CW EC-QCL (mode-hop-free range 1225-1285 cm-1) coupled with long-path absorption spectroscopy was developed for the monitoring of gas-phase hydrogen peroxide (H2O2) using an interference-free absorption line located at 1234.055 cm-1. Wavelength modulation spectroscopy (WMS) with second harmonic detection was implemented for data processing. Optimum levels of pressure and modulation amplitude of the sensor system led to a minimum detection limit (MDL) of 25 ppb using an integration time of 280 sec. The selected absorption line for H2O2, which exhibits no interference from H2O, makes this sensor system suitable for sensitive and selective monitoring of H2O2 levels in decontamination and sterilization processes based on Vapor Phase Hydrogen Peroxide (VPHP) units, in which a mixture of H2O and H2O2 is generated. Furthermore, continuous realtime monitoring of H2O2 concentrations in industrial facilities employing this species can be achieved with this sensing system in order to evaluate average permissible exposure levels (PELs) and potential exceedances of guidelines established by the US Occupational Safety and Health Administration for H2O2.

Probing skin interaction with hydrogen peroxide using diffuse reflectance spectroscopy

NASA Astrophysics Data System (ADS)

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.

The Correlation Between Urinary 8-Iso-Prostaglandin F2α and Hydrogen Peroxide Toward Renal Function in T2DM Patients Consuming Sulfonylurea and Combination of Metformin-Sulfonylurea.

PubMed

Sauriasari, Rani; Wulandari, Fitri; Nurifahmi, Rahmaningtyas; Sekar, Andisyah P; Susilo, Veronika Y

2018-01-01

Renal dysfunction is a common complication in type 2 diabetes mellitus patients associated with oxidative damage which could be characterized by 8-iso-prostaglandin F2α and hydrogen peroxide level as oxidative stress markers. The aim of our study is to determine if there is a difference in 8-iso-prostaglandin F2α and hydrogen peroxide levels between sulfonylurea and combination of metformin-sulfonylurea in diabetic patients. We also wanted to determine if these oxidative stress markers correlate with the estimated Glomerular Filtration Rate (eGFR). We conducted a cross-sectional study with inclusion of 55 patients with type 2 diabetes mellitus in Dr. Sitanala Tangerang Hospital, Indonesia with purposive sampling. The value of eGFR was obtained by serum creatinine levels, while the level of 8-iso-prostaglandin F2α was measured by ELISA and urinary hydrogen peroxide using FOX-1 (Ferrous Ion Oxidation Xylenol Orange 1). There was no difference in 8-iso-prostaglandin F2α and hydrogen peroxide level between the two groups (p=0.088 and p=0.848). Moreover, there was no difference in eGFR values between the two groups, measured by Cockroft-Gault, MDRD, and CKD-EPI. 8-iso-prostaglandin F2α (n=55) was positively correlated with eGFR based on Cockroft-Gault (r=0.382; p=0.009), whereas urinary hydrogen peroxide (n=47) also generate significant positive correlation with eGFR based on the MDRD equation (r=0.326; p=0.021). Linear regression analysis showed that 8-iso-prostaglandin F2α is the most predictive factor and the only significant factor for eGFR in Cockroft-Gault, MDRD and also CKDEPI, even after controlled by gender, age, BMI, HbA1c, systole, and H2O2. The two treatments did not have any significant differences in antioxidant activity. However, an increase of urinary 8-iso-prostaglandin F2. and hydrogen peroxide which correlates with eGFR in the total sample may play a significant role in the pathophysiology of diabetic nephropathy. Copyright© Bentham Science

Enhanced Photoelectrochemical Behavior of H-TiO2 Nanorods Hydrogenated by Controlled and Local Rapid Thermal Annealing

NASA Astrophysics Data System (ADS)

Wang, Xiaodan; Estradé, Sonia; Lin, Yuanjing; Yu, Feng; Lopez-Conesa, Lluis; Zhou, Hao; Gurram, Sanjeev Kumar; Peiró, Francesca; Fan, Zhiyong; Shen, Hao; Schaefer, Lothar; Braeuer, Guenter; Waag, Andreas

2017-05-01

Recently, colored H-doped TiO2 (H-TiO2) has demonstrated enhanced photoelectrochemical (PEC) performance due to its unique crystalline core—disordered shell nanostructures and consequent enhanced conduction behaviors between the core-shell homo-interfaces. Although various hydrogenation approaches to obtain H-TiO2 have been developed, such as high temperature hydrogen furnace tube annealing, high pressure hydrogen annealing, hydrogen-plasma assisted reaction, aluminum reduction and electrochemical reduction etc., there is still a lack of a hydrogenation approach in a controlled manner where all processing parameters (temperature, time and hydrogen flux) were precisely controlled in order to improve the PEC performance of H-TiO2 and understand the physical insight of enhanced PEC performance. Here, we report for the first time a controlled and local rapid thermal annealing (RTA) approach to prepare hydrogenated core-shell H-TiO2 nanorods grown on F:SnO2 (FTO) substrate in order to address the degradation issue of FTO in the typical TiO2 nanorods/FTO system observed in the conventional non-RTA treated approaches. Without the FTO degradation in the RTA approach, we systematically studied the intrinsic relationship between the annealing temperature, structural, optical, and photoelectrochemical properties in order to understand the role of the disordered shell on the improved photoelectrochemical behavior of H-TiO2 nanorods. Our investigation shows that the improvement of PEC performance could be attributed to (i) band gap narrowing from 3.0 to 2.9 eV; (ii) improved optical absorption in the visible range induced by the three-dimensional (3D) morphology and rough surface of the disordered shell; (iii) increased proper donor density; (iv) enhanced electron-hole separation and injection efficiency due to the formation of disordered shell after hydrogenation. The RTA approach developed here can be used as a suitable hydrogenation process for TiO2 nanorods/FTO system for

Enhanced Photoelectrochemical Behavior of H-TiO2 Nanorods Hydrogenated by Controlled and Local Rapid Thermal Annealing.

PubMed

Wang, Xiaodan; Estradé, Sonia; Lin, Yuanjing; Yu, Feng; Lopez-Conesa, Lluis; Zhou, Hao; Gurram, Sanjeev Kumar; Peiró, Francesca; Fan, Zhiyong; Shen, Hao; Schaefer, Lothar; Braeuer, Guenter; Waag, Andreas

2017-12-01

Recently, colored H-doped TiO 2 (H-TiO 2 ) has demonstrated enhanced photoelectrochemical (PEC) performance due to its unique crystalline core-disordered shell nanostructures and consequent enhanced conduction behaviors between the core-shell homo-interfaces. Although various hydrogenation approaches to obtain H-TiO 2 have been developed, such as high temperature hydrogen furnace tube annealing, high pressure hydrogen annealing, hydrogen-plasma assisted reaction, aluminum reduction and electrochemical reduction etc., there is still a lack of a hydrogenation approach in a controlled manner where all processing parameters (temperature, time and hydrogen flux) were precisely controlled in order to improve the PEC performance of H-TiO 2 and understand the physical insight of enhanced PEC performance. Here, we report for the first time a controlled and local rapid thermal annealing (RTA) approach to prepare hydrogenated core-shell H-TiO 2 nanorods grown on F:SnO 2 (FTO) substrate in order to address the degradation issue of FTO in the typical TiO 2 nanorods/FTO system observed in the conventional non-RTA treated approaches. Without the FTO degradation in the RTA approach, we systematically studied the intrinsic relationship between the annealing temperature, structural, optical, and photoelectrochemical properties in order to understand the role of the disordered shell on the improved photoelectrochemical behavior of H-TiO 2 nanorods. Our investigation shows that the improvement of PEC performance could be attributed to (i) band gap narrowing from 3.0 to 2.9 eV; (ii) improved optical absorption in the visible range induced by the three-dimensional (3D) morphology and rough surface of the disordered shell; (iii) increased proper donor density; (iv) enhanced electron-hole separation and injection efficiency due to the formation of disordered shell after hydrogenation. The RTA approach developed here can be used as a suitable hydrogenation process for TiO 2 nanorods

A Silica-Supported Iron Oxide Catalyst Capable of Activating Hydrogen Peroxide at Neutral pH Values

PubMed Central

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

2009-01-01

Iron oxides catalyze the conversion of hydrogen peroxide (H2O2) into oxidants capable of transforming recalcitrant contaminants. Unfortunately, the process is relatively inefficient at circumneutral pH values due to competing reactions that decompose H2O2 without producing oxidants. Silica- and alumina-containing iron oxides prepared by sol-gel processing of aqueous solutions containing Fe(ClO4)3, AlCl3 and tetraethyl orthosilicate efficiently catalyzed the decomposition of H2O2 into oxidants capable of transforming phenol at circumneutral pH values. Relative to hematite, goethite and amorphous FeOOH, the silica-iron oxide catalyst exhibited a stoichiometric efficiency, defined as the number of moles of phenol transformed per mole of H2O2 consumed, that was 10 to 40 times higher than that of the iron oxides. The silica-alumina-iron oxide catalyst had a stoichiometric efficiency that was 50 to 80 times higher than that of the iron oxides. The significant enhancement in oxidant production is attributable to the interaction of Fe with Al and Si in the mixed oxides, which alters the surface redox processes, favoring the production of strong oxidants during H2O2 decomposition. PMID:19943668

Theoretical study of the promotional effect of ZrO2 on In2O3 catalyzed methanol synthesis from CO2 hydrogenation

NASA Astrophysics Data System (ADS)

Zhang, Minhua; Dou, Maobin; Yu, Yingzhe

2018-03-01

Methanol synthesis from CO2 hydrogenation on the ZrO2 doped In2O3(110) surface (Zr-In2O3(110)) with oxygen vacancy has been studied using the density functional theory calculations. The calculated results show that the doped ZrO2 species prohibits the excessive formation of oxygen vacancies and dissociation of H2 on In2O3 surface slightly, but enhances the adsorption of CO2 on both perfect and defective Zr-In2O3(110) surface. Methanol is formed via the HCOO route. The hydrogenation of CO2 to HCOO is both energetically and kinetically facile. The HCOO hydrogenates to polydentate H2CO (p-H2CO) species with an activation barrier of 0.75 eV. H3CO is produced from the hydrogenation of monodentate H2CO (mono-H2CO), transformation from p-H2CO with 0.82 eV reaction energy, with no barrier whether there is hydroxyl group between the mono-H2CO and the neighboring hydride or not. Methanol is the product of H3CO protonation with 0.75 eV barrier. The dissociation and protonation of CO2 are both energetically and kinetically prohibited on Zr-In2O3(110) surface. The doped ZrO2 species can further enhance the adsorption of all the intermediates involved in CO2 hydrogenation to methanol, activate the adsorbed CO2 and H2CO, and stabilize the HCOO, H2CO and H3CO, especially prohibit the dissociation of H2CO or the reaction of H2CO with neighboring hydride to form HCOO and gas phase H2. All these effects make the ZrO2 supported In2O3 catalyst exhibit higher activity and selectivity on methanol synthesis from CO2 hydrogenation.

Protein degradation following treatment with hydrogen peroxide.

PubMed Central

Fligiel, S. E.; Lee, E. C.; McCoy, J. P.; Johnson, K. J.; Varani, J.

1984-01-01

Pretreatment of hemoglobin with 50-5000 nmol hydrogen peroxide (H2O2) increased its susceptibility to proteolysis by a number of purified enzymes, including trypsin, chymotrypsin, elastase, and plasmin, and by the neutral protease of rat peritoneal leukocytes. Pretreatment of the protein substrate with catalase-inactivated H2O2 had no effect. Separation of the proteolytic fragments by G-75 Sephadex gel filtration indicated no apparent differences in the size distribution of the fragments produced by treatment with the H2O2/proteolytic enzyme combination as compared with enzyme treatment alone. A partially purified preparation of rat glomerular basement membrane was also treated with proteolytic enzyme alone or in combination with H2O2. As with the hemoglobin, pretreatment of the glomerular basement membrane with H2O2 increased its susceptibility to subsequent proteolytic attack. In addition, treatment of a basement membrane glycoprotein, fibronectin, with H2O2 also increased its sensitivity to subsequent proteolysis. These results suggest that in addition to their other proinflammatory activities, oxygen-derived metabolites may contribute to tissue destruction by altering the susceptibility of proteins to hydrolytic enzymes. Images Figure 1 PMID:6375392

FLYING-WATER Renewables-H2-H2O TERRAFORMING: PERMANENT Drought(s)-Elimination FOREVER!!!

NASA Astrophysics Data System (ADS)

Lyons, M.; Siegel, E.

2010-03-01

``Water water everywhere; ne'er a drop to drink''[Coleridg(1798)]; now:``Hydrogen hydrogen everywhere;STILL ne'er a drop to drink'': ONLY H2 can be ``FLYING-WATER''/``chemical-rain-in-pipelines''/ ``Hindenberg-effect (H2-UP;H2O-DOWN): atomic-weights ratio: O/H2O=[16]/[18]˜90%; O already in air uphill; NO H2O pumping need! In water-starved glacial-melting world, rescue ONLY by Siegel[3rd Intl.Conf.Alt.Energy,Hemisphere/Springer(1980)- vol.5/ p.459]Renewables-H2-H2O purposely flexible versatile agile customizable scaleable retrofitable integrated operating- system. Rosenfeld[Sci.315,1396(3/9/2007)]-Biello[Sci.Am.(3/9/ 2007)]crucial geomorphology which ONLY maximal-buoyancy light- est-element H2 can exploit, to again make ``Mountains into Fount- ains": Siegel ``terra-forming''(and ocean-rebasificaton!!!) long pre-``Holdren''-``Ciccerine" ``geo-enginering'', only via Siegel proprietary magnetic-hydrogen-valve permits H2 flow in already in-ground dense BCC/ferritic-steels pipelines-network (NO new infrastructure) counters Tromp[Sci.300,1740(03)]global-pandemics (cancers/blindness/famine)dire-warning about H2-(ALONE)economy CATASTROPHIC H2 ozone-layer destruction sobering cavat to dangerous H2-automotion-economy panacea hype!

Influence of γ-radiation on the reactivity of montmorillonite towards H 2O 2

NASA Astrophysics Data System (ADS)

Holmboe, Michael; Jonsson, Mats; Wold, Susanna

2012-02-01

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

Carbon Nitride-Aromatic Diimide-Graphene Nanohybrids: Metal-Free Photocatalysts for Solar-to-Hydrogen Peroxide Energy Conversion with 0.2% Efficiency.

PubMed

Kofuji, Yusuke; Isobe, Yuki; Shiraishi, Yasuhiro; Sakamoto, Hirokatsu; Tanaka, Shunsuke; Ichikawa, Satoshi; Hirai, Takayuki

2016-08-10

Solar-to-chemical energy conversion is a challenging subject for renewable energy storage. In the past 40 years, overall water splitting into H2 and O2 by semiconductor photocatalysis has been studied extensively; however, they need noble metals and extreme care to avoid explosion of the mixed gases. Here we report that generating hydrogen peroxide (H2O2) from water and O2 by organic semiconductor photocatalysts could provide a new basis for clean energy storage without metal and explosion risk. We found that carbon nitride-aromatic diimide-graphene nanohybrids prepared by simple hydrothermal-calcination procedure produce H2O2 from pure water and O2 under visible light (λ > 420 nm). Photoexcitation of the semiconducting carbon nitride-aromatic diimide moiety transfers their conduction band electrons to graphene and enhances charge separation. The valence band holes on the semiconducting moiety oxidize water, while the electrons on the graphene moiety promote selective two-electron reduction of O2. This metal-free system produces H2O2 with solar-to-chemical energy conversion efficiency 0.20%, comparable to the highest levels achieved by powdered water-splitting photocatalysts.

Fibrous Catalyst-Enhanced Acanthamoeba Disinfection by Hydrogen Peroxide.

PubMed

Kilvington, Simon; Winterton, Lynn

2017-11-01

Hydrogen peroxide (H2O2) disinfection systems are contact-lens-patient problem solvers. The current one-step, criterion-standard version has been widely used since the mid-1980s, without any significant improvement. This work identifies a potential next-generation, one-step H2O2, not based on the solution formulation but rather on a case-based peroxide catalyst. One-step H2O2 systems are widely used for contact lens disinfection. However, antimicrobial efficacy can be limited because of the rapid neutralization of the peroxide from the catalytic component of the systems. We studied whether the addition of an iron-containing catalyst bound to a nonfunctional propylene:polyacryonitrile fabric matrix could enhance the antimicrobial efficacy of these one-step H2O2 systems. Bausch + Lomb PeroxiClear and AOSept Plus (both based on 3% H2O2 with a platinum-neutralizing disc) were the test systems. These were tested with and without the presence of the catalyst fabric using Acanthamoeba cysts as the challenge organism. After 6 hours' disinfection, the number of viable cysts was determined. In other studies, the experiments were also conducted with biofilm formed by Stenotrophomonas maltophilia and Elizabethkingia meningoseptica bacteria. Both control systems gave approximately 1-log10 kill of Acanthamoeba cysts compared with 3.0-log10 kill in the presence of the catalyst (P < .001). In the biofilm studies, no viable bacteria were recovered following disinfection in the presence of the catalyst compared with ≥3.0-log10 kill when it was omitted. In 30 rounds' recurrent usage, the experiments, in which the AOSept Plus system was subjected to 30 rounds of H2O2 neutralization with or without the presence of catalytic fabric, showed no loss in enhanced biocidal efficacy of the material. The catalytic fabric was also shown to not retard or increase the rate of H2O2 neutralization. We have demonstrated the catalyst significantly increases the efficacy of one-step H2O2

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

PubMed

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

2017-03-06

Oxidation of pyrite (FeS 2 ) plays a significant role in the redox cycling of iron and sulfur on Earth and is the primary cause of acid mine drainage (AMD). It has been established that this process involves multi-step electron-transfer reactions between surface defects and adsorbed O 2 and H 2 O, releasing sulfoxy species (e.g., S 2 O 3 2- , SO 4 2- ) and ferrous iron (Fe 2+ ) to the solution and also producing intermediate by-products, such as hydrogen peroxide (H 2 O 2 ) and other reactive oxygen species (ROS), however, our understanding of the kinetics of these transient species is still limited. We investigated the kinetics of H 2 O 2 formation in aqueous suspensions of FeS 2 microparticles by monitoring, in real time, the H 2 O 2 and dissolved O 2 concentration under oxic and anoxic conditions using amperometric microsensors. Additional spectroscopic and structural analyses were done to track the dependencies between the process of FeS 2 dissolution and the degradation of H 2 O 2 through the Fenton reaction. Based on our experimental results, we built a kinetic model which explains the observed trend of H 2 O 2 , showing that FeS 2 dissolution can act as a natural Fenton reagent, influencing the oxidation of third-party species during the long term evolution of geochemical systems, even in oxygen-limited environments.

Effect of hydrogen peroxide pretreatment on the structural features and the enzymatic hydrolysis of rice straw.

PubMed

Wei, C J; Cheng, C Y

1985-10-01

Assessment was made to evaluate the effect of hydrogen peroxide pretreatment on the change of the structural features and the enzymatic hydrolysis of rice straw. Changes in the lignin content, weight loss, accessibility for Cadoxen, water holding capacity, and crystallinity of straw were measured during pretreatment to express the modification of the lignocellulosic structure of straw. The rates and the extents of enzymatic hydrolysis, cellulase adsorption, and cellobiose accumulation in the initial stage of hydrolysis were determined to study the pretreatment effect on hydrolysis. Pretreatment at 60 degrees C for 5 h in a solution with 1% (w/w) H(2)O(2) and NaOH resulted in 60% delignification, 40% weight loss, a fivefold increase in the accessibility for Cadoxen, an one times increase in the water-holding capacity, and only a slight decrease in crystallinity as compared with that of the untreated straw. Improvement on the pretreatment effect could be made by increasing the initial alkalinity and the pretreatment temperature of hydrogen peroxide solution. A saturated improvement on the structural features was found when the weight ratio of hydrogen peroxide to straw was above 0.25 g H(2)O(2)/g straw in an alkaline H(2)O(2) solution with 1% (w/w) NaOH at 32 degrees C. The initial rates and extents of hydrolysis, cellulase adsorption, and cellobiose accumulation in hydrolysis were enhanced in accordance with the improved structural features of straw pretreated. A four times increase in the extent of the enzymatic hydrolysis of straw for 24 h was attributed to the alkaline hydrogen peroxide pretreatment.

Ionic Transport through Chemically Functionalized Hydrogen Peroxide-Sensitive Asymmetric Nanopores.

PubMed

Ali, Mubarak; Ahmed, Ishtiaq; Nasir, Saima; Ramirez, Patricio; Niemeyer, Christof M; Mafe, Salvador; Ensinger, Wolfgang

2015-09-09

We describe the fabrication of a chemical-sensitive nanofluidic device based on asymmetric nanopores whose transport characteristics can be modulated upon exposure to hydrogen peroxide (H2O2). We show experimentally and theoretically that the current-voltage curves provide a suitable method to monitor the H2O2-mediated change in pore surface characteristics from the electronic readouts. We demonstrate also that the single pore characteristics can be scaled to the case of a multipore membrane whose electric outputs can be readily controlled. Because H2O2 is an agent significant for medical diagnostics, the results should be useful for sensing nanofluidic devices.

OH+ and H2O+: Probes of the Molecular Hydrogen Fraction and Cosmic-Ray Ionization Rate

NASA Astrophysics Data System (ADS)

Indriolo, Nick; Neufeld, D. A.; Gerin, M.; PRISMAS; WISH

2014-01-01

The fast ion-molecule chemistry that occurs in the interstellar medium (ISM) is initiated by cosmic-ray ionization of both atomic and molecular hydrogen. Species that are near the beginning of the network of interstellar chemistry such as the oxygen-bearing ions OH+ and H2O+ can be useful probes of the cosmic-ray ionization rate. This parameter is of particular interest as, to some extent, it controls the abundances of several molecules. Using observations of OH+ and H2O+ made with HIFI on board Herschel, we have inferred the cosmic-ray ionization rate of atomic hydrogen in multiple distinct clouds along 12 Galactic sight lines. These two molecules also allow us to determine the molecular hydrogen fraction (amount of hydrogen nuclei in H2 versus H) as OH+ and H2O+ abundances are dependent on the competition between dissociative recombination with electrons and hydrogen abstraction reactions involving H2. Our observations of OH+ and H2O+ indicate environments where H2 accounts for less than 10% of the available hydrogen nuclei, suggesting that these species primarily reside in the diffuse, atomic ISM. Average ionization rates in this gas are on the order of a few times 10-16 s-1, with most values in specific clouds above or below this average by a factor of 3 or so. This result is in good agreement with the most up-to-date determination of the distribution of cosmic-ray ionization rates in diffuse molecular clouds as inferred from observations of H3+.

Hydrogen peroxide concentration by pervaporation of a ternary liquid solution in microfluidics.

PubMed

Ziemecka, Iwona; Haut, Benoît; Scheid, Benoit

2015-01-21

Pervaporation in a microfluidic device is performed on liquid ternary solutions of hydrogen peroxide-water-methanol in order to concentrate hydrogen peroxide (H2O2) by removing methanol. The quantitative analysis of the pervaporation of solutions with different initial compositions is performed, varying the operating temperature of the microfluidic device. Experimental results together with a mathematical model of the separation process are used to understand the effect of the operating conditions on the microfluidic device efficiency. The parameters influencing significantly the performance of pervaporation in the microfluidic device are determined and the limitations of the process are discussed. For the analysed system, the operating temperature of the chip has to be below the temperature at which H2O2 decomposes. Therefore, the choice of an adequate reduced operating pressure is required, depending on the expected separation efficiency.

High loading MnO2 nanowires on graphene paper: facile electrochemical synthesis and use as flexible electrode for tracking hydrogen peroxide secretion in live cells.

PubMed

Dong, Shuang; Xi, Jiangbo; Wu, Yanan; Liu, Hongwei; Fu, Chaoyang; Liu, Hongfang; Xiao, Fei

2015-01-01

Recent progress in flexible and lightweight electrochemical sensor systems requires the development of paper-like electrode materials. Here, we report a facile and green synthesis of a new type of MnO2 nanowires-graphene nanohybrid paper by one-step electrochemical method. This strategy demonstrates a collection of unique features including the effective electrochemical reduction of graphene oxide (GO) paper and the high loading of MnO2 nanowires on electrochemical reduced GO (ERGO) paper. When used as flexible electrode for nonenzymatic detection of hydrogen peroxide (H2O2), MnO2-ERGO paper exhibits high electrocatalytic activity toward the redox of H2O2 as well as excellent stability, selectivity and reproducibility. The amperometric responses are linearly proportional to H2O2 concentration in the range 0.1-45.4 mM, with a detection limit of 10 μM (S/N=3) and detection sensitivity of 59.0 μA cm(-2) mM(-1). These outstanding sensing performances enable the practical application of MnO2-ERGO paper electrode for the real-time tracking H2O2 secretion by live cells macrophages. Therefore, the proposed graphene-based nanohybrid paper electrode with intrinsic flexibility, tailorable shapes and adjustable properties can contribute to the full realization of high-performance flexible electrode material used in point-of-care testing devices and portable instruments for in-vivo clinical diagnostics and on-site environmental monitoring. Copyright © 2014 Elsevier B.V. All rights reserved.

Hydrogenated TiO2 nanotube arrays for supercapacitors.

PubMed

Lu, Xihong; Wang, Gongming; Zhai, Teng; Yu, Minghao; Gan, Jiayong; Tong, Yexiang; Li, Yat

2012-03-14

We report a new and general strategy for improving the capacitive properties of TiO(2) materials for supercapacitors, involving the synthesis of hydrogenated TiO(2) nanotube arrays (NTAs). The hydrogenated TiO(2) (denoted as H-TiO(2)) were obtained by calcination of anodized TiO(2) NTAs in hydrogen atmosphere in a range of temperatures between 300 to 600 °C. The H-TiO(2) NTAs prepared at 400 °C yields the largest specific capacitance of 3.24 mF cm(-2) at a scan rate of 100 mV s(-1), which is 40 times higher than the capacitance obtained from air-annealed TiO(2) NTAs at the same conditions. Importantly, H-TiO(2) NTAs also show remarkable rate capability with 68% areal capacitance retained when the scan rate increase from 10 to 1000 mV s(-1), as well as outstanding long-term cycling stability with only 3.1% reduction of initial specific capacitance after 10,000 cycles. The prominent electrochemical capacitive properties of H-TiO(2) are attributed to the enhanced carrier density and increased density of hydroxyl group on TiO(2) surface, as a result of hydrogenation. Furthermore, we demonstrate that H-TiO(2) NTAs is a good scaffold to support MnO(2) nanoparticles. The capacitor electrodes made by electrochemical deposition of MnO(2) nanoparticles on H-TiO(2) NTAs achieve a remarkable specific capacitance of 912 F g(-1) at a scan rate of 10 mV s(-1) (based on the mass of MnO(2)). The ability to improve the capacitive properties of TiO(2) electrode materials should open up new opportunities for high-performance supercapacitors. © 2012 American Chemical Society

Oxidation and Destruction of Polyvinyl Alcohol under the Combined Action of Ozone-Oxygen Mixture and Hydrogen Peroxide

NASA Astrophysics Data System (ADS)

Zimin, Yu. S.; Kutlugil'dina, G. G.; Mustafin, A. G.

2018-03-01

The oxidative transformations of a polyvinyl alcohol in aqueous solutions are studied under the simultaneous action of the two oxidizing agents, an ozone-oxygen mixture and a hydrogen peroxide. Effective parameters a and b, which characterize the first and second channels of carboxyl group accumulation, respectively, grow linearly upon an increase in the initial concentration of H2O2. After the temperature dependence of a and b parameters (331-363 K) in a PVA + O3 + O2 + H2O2 + H2O reaction system is studied, the parameters of the activation of COOH group accumulation are found (where PVA is a polyvinyl alcohol). New data on the effect process conditions (length of oxidation, temperature, and hydrogen peroxide concentration) have on the degree of destructive transformations of polyvinyl alcohol in the investigated reaction system are obtained.

Effect of pH on whitening efficacy of 35% hydrogen peroxide and enamel microhardness.

PubMed

Jurema, Ana Luiza Barbosa; de Souza, Mauricio Yugo; Torres, Carlos Rocha Gomes; Borges, Alessandra Bühler; Caneppele, Taciana Marco Ferraz

2018-03-01

This study aimed to evaluate the effect of 35% hydrogen peroxide at different pH values and the degree of tooth staining on whitening efficacy and enamel microhardness. 90 enamel-dentin specimens were obtained from bovine incisors. They were randomly divided into 2 groups (n = 45), 1 group was immersed in a staining broth for 14 days, and another group was not stained and kept in distilled water at 37°C. Twenty-four hours after the staining procedure, each group was distributed into 3 subgroups that were whitened by 35% hydrogen peroxide with different pH values (5, 7, and 8.4) for 30 minutes. The color was measured at baseline and 7 days after whitening. Microhardness was measured at baseline, immediate, 24 hours, and 1 month after the whitening procedure. Data were submitted to 2-way analysis of variance (ANOVA) and the Tukey test for multiple comparisons for color analysis. Repeated measures ANOVA and the Tukey test were used to analyze microhardness data. The color change of the stained groups (ΔE 00  = 4.6) was significantly higher than that of the nonstained groups (ΔE 00  = 3.7). Microhardness value decreased significantly immediately after whitening for all subgroups and did not return to initial values. For each measurement time, microhardness was not significantly different among subgroups with different pH values. Despite the effectiveness of 35% hydrogen peroxide, changes on gel pH did not affect the whitening efficacy, and the enamel was superficially demineralized, regardless of pH values. Independently of the pH value of whitening gel, enamel undergoes superficial demineralization and with a reduction in superficial microhardness that does not return to the initial values. However, using hydrogen peroxide with different pH values does not alter the whitening effect. © 2018 Wiley Periodicals, Inc.

Direct and Selective Synthesis of Hydrogen Peroxide over Palladium-Tellurium Catalysts at Ambient Pressure.

PubMed

Tian, Pengfei; Xu, Xingyan; Ao, Can; Ding, Doudou; Li, Wei; Si, Rui; Tu, Weifeng; Xu, Jing; Han, Yi-Fan

2017-09-11

Highly selective hydrogen peroxide (H 2 O 2 ) synthesis directly from H 2 and O 2 is a strongly desired reaction for green processes. Herein a highly efficient palladium-tellurium (Pd-Te/TiO 2 ) catalyst with a selectivity of nearly 100 % toward H 2 O 2 under mild conditions (283 K, 0.1 MPa, and a semi-batch continuous flow reactor) is reported. The size of Pd particles was remarkably reduced from 2.1 nm to 1.4 nm with the addition of Te. The Te-modified Pd surface could significantly weaken the dissociative activation of O 2 , leading to the non-dissociative hydrogenation of O 2 . Density functional theory calculations illuminated the critical role of Te in the selective hydrogenation of O 2 , in that the active sites composed of Pd and Te could significantly restrain side reactions. This work has made significant progress on the development of high-selectivity catalysts for the direct synthesis of H 2 O 2 at ambient pressure. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Decomposition of 3,5-dinitrobenzamide in aqueous solution during UV/H2O2 and UV/TiO2 oxidation processes.

PubMed

Yan, Yingjie; Liao, Qi-Nan; Ji, Feng; Wang, Wei; Yuan, Shoujun; Hu, Zhen-Hu

2017-02-01

3,5-Dinitrobenzamide has been widely used as a feed additive to control coccidiosis in poultry, and part of the added 3,5-dinitrobenzamide is excreted into wastewater and surface water. The removal of 3,5-dinitrobenzamide from wastewater and surface water has not been reported in previous studies. Highly reactive hydroxyl radicals from UV/hydrogen peroxide (H 2 O 2 ) and UV/titanium dioxide (TiO 2 ) advanced oxidation processes (AOPs) can decompose organic contaminants efficiently. In this study, the decomposition of 3,5-dinitrobenzamide in aqueous solution during UV/H 2 O 2 and UV/TiO 2 oxidation processes was investigated. The decomposition of 3,5-dinitrobenzamide fits well with a fluence-based pseudo-first-order kinetics model. The decomposition in both two oxidation processes was affected by solution pH, and was inhibited under alkaline conditions. Inorganic anions such as NO 3 - , Cl - , SO 4 2- , HCO 3 - , and CO 3 2- inhibited the degradation of 3,5-dinitrobenzamide during the UV/H 2 O 2 and UV/TiO 2 oxidation processes. After complete decomposition in both oxidation processes, approximately 50% of 3,5-dinitrobenzamide was decomposed into organic intermediates, and the rest was mineralized to CO 2 , H 2 O, and other inorganic anions. Ions such as NH 4 + , NO 3 - , and NO 2 - were released into aqueous solution during the degradation. The primary decomposition products of 3,5-dinitrobenzamide were identified using time-of-flight mass spectrometry (LCMS-IT-TOF). Based on these products and ions release, a possible decomposition pathway of 3,5-dinitrobenzamide in both UV/H 2 O 2 and UV/TiO 2 processes was proposed.

A Key Role for Apoplastic H2O2 in Norway Spruce Phenolic Metabolism.

PubMed

Laitinen, Teresa; Morreel, Kris; Delhomme, Nicolas; Gauthier, Adrien; Schiffthaler, Bastian; Nickolov, Kaloian; Brader, Günter; Lim, Kean-Jin; Teeri, Teemu H; Street, Nathaniel R; Boerjan, Wout; Kärkönen, Anna

2017-07-01

Apoplastic events such as monolignol oxidation and lignin polymerization are difficult to study in intact trees. To investigate the role of apoplastic hydrogen peroxide (H 2 O 2 ) in gymnosperm phenolic metabolism, an extracellular lignin-forming cell culture of Norway spruce ( Picea abies ) was used as a research model. Scavenging of apoplastic H 2 O 2 by potassium iodide repressed lignin formation, in line with peroxidases activating monolignols for lignin polymerization. Time-course analyses coupled to candidate substrate-product pair network propagation revealed differential accumulation of low-molecular-weight phenolics, including (glycosylated) oligolignols, (glycosylated) flavonoids, and proanthocyanidins, in lignin-forming and H 2 O 2 -scavenging cultures and supported that monolignols are oxidatively coupled not only in the cell wall but also in the cytoplasm, where they are coupled to other monolignols and proanthocyanidins. Dilignol glycoconjugates with reduced structures were found in the culture medium, suggesting that cells are able to transport glycosylated dilignols to the apoplast. Transcriptomic analyses revealed that scavenging of apoplastic H 2 O 2 resulted in remodulation of the transcriptome, with reduced carbon flux into the shikimate pathway propagating down to monolignol biosynthesis. Aggregated coexpression network analysis identified candidate enzymes and transcription factors for monolignol oxidation and apoplastic H 2 O 2 production in addition to potential H 2 O 2 receptors. The results presented indicate that the redox state of the apoplast has a profound influence on cellular metabolism. © 2017 American Society of Plant Biologists. All Rights Reserved.

Dissolution of Uranium(IV) Oxide in Solutions of Ammonium Carbonate and Hydrogen Peroxide

DOE Office of Scientific and Technical Information (OSTI.GOV)

Smith, Steven C.; Peper, Shane M.; Douglas, Matthew

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 inmore » 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.« less

Nanostructured N-doped TiO2 marigold flowers for an efficient solar hydrogen production from H2S

NASA Astrophysics Data System (ADS)

Chaudhari, Nilima S.; Warule, Sambhaji S.; Dhanmane, Sushil A.; Kulkarni, Milind V.; Valant, Matjaz; Kale, Bharat B.

2013-09-01

Nitrogen-doped TiO2 nanostructures in the form of marigold flowers have been synthesized for the first time using a facile solvothermal method. The structural analysis has shown that such an N-doped TiO2 system crystallizes in the anatase structure. The optical absorption spectra have clearly shown the shift in the absorption edge towards the visible-light range, which indicates successful nitrogen doping. The nitrogen doping has been further confirmed by photoluminescence and photoemission spectroscopy. Microscopy studies have shown the thin nanosheets (petals) of N-TiO2 with a thickness of ~2-3 nm, assembled in the form of the marigold flower with a high surface area (224 m2 g-1). The N-TiO2 nanostructure with marigold flowers is an efficient photocatalyst for the decomposition of H2S and production of hydrogen under solar light. The maximum hydrogen evolution obtained is higher than other known N-TiO2 systems. It is noteworthy that photohydrogen production using the unique marigold flowers of N-TiO2 from abundant H2S under solar light is hitherto unattempted. The proposed synthesis method can also be utilized to design other hierarchical nanostructured N-doped metal oxides.Nitrogen-doped TiO2 nanostructures in the form of marigold flowers have been synthesized for the first time using a facile solvothermal method. The structural analysis has shown that such an N-doped TiO2 system crystallizes in the anatase structure. The optical absorption spectra have clearly shown the shift in the absorption edge towards the visible-light range, which indicates successful nitrogen doping. The nitrogen doping has been further confirmed by photoluminescence and photoemission spectroscopy. Microscopy studies have shown the thin nanosheets (petals) of N-TiO2 with a thickness of ~2-3 nm, assembled in the form of the marigold flower with a high surface area (224 m2 g-1). The N-TiO2 nanostructure with marigold flowers is an efficient photocatalyst for the decomposition of H2S and

Pd nanoparticle-modified electrodes for nonenzymatic hydrogen peroxide detection

NASA Astrophysics Data System (ADS)

Wang, Jue; Chen, Xue-jiao; Liao, Kai-ming; Wang, Guang-hou; Han, Min

2015-08-01

A hydrogen peroxide (H2O2) sensor based on Pd nanoparticles (NPs) and glassy carbon electrodes (GCEs) is fabricated. Pd NPs are deposited on GCEs by using a gas phase cluster beam deposition technique. The NP-deposited electrodes show enhanced electrocatalytic activity in reduction of H2O2. The electrode with an optimized NP coverage of 85 % has a high selective and stable nonenzymatic sensing ability of H2O2 with a low detection limit (3.4 × 10-7 M), high sensitivity (50.9 μA mM-1), and a wide linear range (from 1.0 × 10-6 to 6.0 × 10-3 M). The reduction peak potential of the electrode is close to -0.12 V, which enables high selective amperometric detection of H2O2 at a low applied potential.