WorldWideScience

Sample records for solid h2o ice

  1. Solid organic residues produced by irradiation of hydrocarbon-containing H2O and H2O/NH3 ices - Infrared spectroscopy and astronomical implications

    International Nuclear Information System (INIS)

    Khare, B.N.; Thompson, W.R.; Murray, B.G.J.P.T.; Chyba, C.F.; Sagan, C.

    1989-01-01

    Plasma-discharge irradiations were conducted for the methane clathrate expected in outer solar system satellites and cometary nuclei; also irradiated were ices prepared from other combinations of H 2 O with CH 4 , C 2 H 6 , or C 2 H 2 . Upon evaporation of the yellowish-to-tan irradiated ices, it is found that a colored solid film adheres to the walls of the reaction vessel at room temperature. These organic films are found to exhibit IR band identifiable with alkane, aldehide, alcohol, and perhaps alkene, as well as substituted aromatic functional groups. These spectra are compared with previous studies of UV- or photon-irradiated nonclathrated hydrocarbon-containing ices. 73 refs

  2. Longitudinal sound velocities, elastic anisotropy, and phase transition of high-pressure cubic H2O ice to 82 GPa

    Science.gov (United States)

    Kuriakose, Maju; Raetz, Samuel; Hu, Qing Miao; Nikitin, Sergey M.; Chigarev, Nikolay; Tournat, Vincent; Bulou, Alain; Lomonosov, Alexey; Djemia, Philippe; Gusev, Vitalyi E.; Zerr, Andreas

    2017-10-01

    Water ice is a molecular solid whose behavior under compression reveals the interplay of covalent bonding in molecules and forces acting between them. This interplay determines high-pressure phase transitions, the elastic and plastic behavior of H2O ice, which are the properties needed for modeling the convection and internal structure of the giant planets and moons of the solar system as well as H2O -rich exoplanets. We investigated experimentally and theoretically elastic properties and phase transitions of cubic H2O ice at room temperature and high pressures between 10 and 82 GPa. The time-domain Brillouin scattering (TDBS) technique was used to measure longitudinal sound velocities (VL) in polycrystalline ice samples compressed in a diamond anvil cell. The high spatial resolution of the TDBS technique revealed variations of VL caused by elastic anisotropy, allowing us to reliably determine the fastest and the slowest sound velocity in a single crystal of cubic H2O ice and thus to evaluate existing equations of state. Pressure dependencies of the single-crystal elastic moduli Ci j(P ) of cubic H2O ice to 82 GPa have been obtained which indicate its hardness and brittleness. These results were compared with ab initio calculations. It is suggested that the transition from molecular ice VII to ionic ice X occurs at much higher pressures than proposed earlier, probably above 80 GPa.

  3. Influence of isotopic disorder on solid state amorphization and polyamorphism in solid H2O -D2O solutions

    Science.gov (United States)

    Gromnitskaya, E. L.; Danilov, I. V.; Lyapin, A. G.; Brazhkin, V. V.

    2015-10-01

    We present a low-temperature and high-pressure ultrasonic study of elastic properties of isotopic H2O-D2O solid solutions, comparing their properties with those of the isotopically pure H2O and D2O ices. Measurements were carried out for solid state amorphization (SSA) from 1h to high-density amorphous (HDA) ice upon compression up to 1.8 GPa at 77 K and for the temperature-induced (77 -190 K ) u-HDA (unrelaxed HDA) → e-HDA (expanded HDA) → low-density amorphous (LDA )→1 c cascade of ice transformations near room pressure. There are many similarities in the elasticity behaviour of H2O ,D2O , and H2O-D2O solid solutions, including the softening of the shear elastic modulus as a precursor of SSA and the HDA →LDA transition. We have found significant isotopic effects during H/D substitution, including elastic softening of H2O -D2O solid solutions with respect to the isotopically pure ices in the case of the bulk moduli of ices 1c and 1h and for both bulk and shear elastic moduli of HDA ice at high pressures (>1 GPa ) . This softening is related to the configurational isotopic disorder in the solid solutions. At low pressures, the isotope concentration dependence of the elastic moduli of u-HDA ice changes remarkably and becomes monotonic with pronounced change of the bulk modulus (≈20 %) .

  4. Laboratory Infrared Spectra of Polycyclic Aromatic Nitrogen Heterocycles: Quinoline, and Phenanthridine in Solid Argon and H2O

    Science.gov (United States)

    Bernstein, M. P.; Mattioda, A. L.; Sandford, S. A.; Hudgins, D. M.

    2004-01-01

    Polycyclic aromatic hydrocarbons (PAHs) are common throughout the universe. Their detection and identification are based on telescopic infrared (IR) spectra compared with laboratory data. Polycyclic Aromatic Nitrogen Heterocycles (PANHs) are heterocyclic aromatics i.e., PAHs with carbon atoms replaced by a nitrogen atom. These molecules should be present in the interstellar medium, but have received relatively little attention. We present mid-IR spectra of two PANHs, quinoline (C9H7N), and phenanthridine (C13H9N) isolated in solid argon and frozen in solid H2O at 12 K, conditions yielding data directly comparable to astronomical observations. In contrast to simple PAHs, that do not interact strongly with solid H2O, the nitrogen atoms in PANHs are potentially capable of hydrogen bonding with H2O. Whereas the IR spectrum of phenanthridine in H2O is similar to that of the same compound isolated in an argon matrix, quinoline absorptions shift up to 16 cm(sup -1) (0.072 mm) between argon and H2O. Thus, astronomers will not always be able to rely on IR band positions of matrix isolated PANHs to correctly interpret the absorptions of PANHs frozen in H2O ice grains. Furthermore, our data suggest that relative band areas also vary, so determining column densities to better than a factor of 3 will require knowledge of the matrix in which the PANH is embedded and laboratory studies of relevant samples.

  5. Ultraviolet Irradiation of Naphthalene in H2O Ice: Implications for Meteorites and Biogenesis

    Science.gov (United States)

    Bernstein, Max P.; Dworkin, Jason; Sandford, Scott A.; Allamandola, Louis J.; DeVincenzi, Donald L. (Technical Monitor)

    2000-01-01

    The polycyclic aromatic hydrocarbon (PAH) naphthalene was exposed to ultraviolet radiation in H2O ice under astrophysical conditions, and the products were analyzed using infrared spectroscopy and high performance liquid chromatography. As we found in our earlier studies on the photoprocessing of coronene in H2O ice, aromatic alcohols and ketones (quinones) were formed. The regiochemistry of the reactions is described and leads to specific predictions of the relative abundances of various oxidized naphthalenes that should exist in meteorites if interstellar ice photochemistry influenced their aromatic inventory. Since oxidized PAHs are present in carbon-rich meteorites and interplanetary dust particles (IDPs), and ubiquitous in and fundamental to biochemistry, the delivery of such extraterrestrial molecules to the early Earth may have played a role in the origin and evolution of life.

  6. Interannual observations and quantification of summertime H2O ice deposition on the Martian CO2 ice south polar cap

    Science.gov (United States)

    Brown, Adrian J.; Piqueux, Sylvain; Titus, Timothy N.

    2014-01-01

    The spectral signature of water ice was observed on Martian south polar cap in 2004 by the Observatoire pour l'Mineralogie, l'Eau les Glaces et l'Activite (OMEGA) ( Bibring et al., 2004). Three years later, the OMEGA instrument was used to discover water ice deposited during southern summer on the polar cap ( Langevin et al., 2007). However, temporal and spatial variations of these water ice signatures have remained unexplored, and the origins of these water deposits remains an important scientific question. To investigate this question, we have used observations from the Compact Reconnaissance Imaging Spectrometer for Mars (CRISM) instrument on the Mars Reconnaissance Orbiter (MRO) spacecraft of the southern cap during austral summer over four Martian years to search for variations in the amount of water ice. We report below that for each year we have observed the cap, the magnitude of the H2O ice signature on the southern cap has risen steadily throughout summer, particularly on the west end of the cap. The spatial extent of deposition is in disagreement with the current best simulations of deposition of water ice on the south polar cap (Montmessin et al., 2007). This increase in water ice signatures is most likely caused by deposition of atmospheric H2O ice and a set of unusual conditions makes the quantification of this transport flux using CRISM close to ideal. We calculate a ‘minimum apparent‘ amount of deposition corresponding to a thin H2O ice layer of 0.2 mm (with 70% porosity). This amount of H2O ice deposition is 0.6–6% of the total Martian atmospheric water budget. We compare our ‘minimum apparent’ quantification with previous estimates. This deposition process may also have implications for the formation and stability of the southern CO2 ice cap, and therefore play a significant role in the climate budget of modern day Mars.

  7. Matrix Isolation Spectroscopy of H2O2, D2O, and HDO in Solid Parahydrogen

    National Research Council Canada - National Science Library

    Fajardo, Mario

    2003-01-01

    ...) solids doped with H2O, D2O and HDO molecules. Analysis of the rovibrational spectra of the isolated H20, D2O and HDO monomers reveals their existence as very slightly hindered rotors, typically showing only 2 to 5...

  8. The Radiolytic Destruction of Glycine Diluted in H2O and CO2 Ice: Implications for Mars and Other Planetary Environments

    Science.gov (United States)

    Gerakines, Perry A.; Hudson, R. L.

    2013-10-01

    Future missions to Mars and other planetary surfaces will probe under the surfaces of these worlds for signs of organic chemistry. In previous studies we have shown that glycine and other amino acids have radiolytic destruction rates that depend on temperature and on dilution within an H2O ice matrix (Gerakines et al., 2012; Gerakines and Hudson 2013). In the new work presented here, we have examined the destruction of glycine diluted in CO2 ice at various concentrations and irradiated with protons at 0.8 MeV, typical of cosmic rays and solar energetic particles. Destruction rates for glycine were measured by infrared spectroscopy in situ, without removing or warming the ice samples. New results on the half life of glycine in solid CO2 will be compared to those found in H2O ice matrices. The survivability of glycine in icy planetary surfaces rich in H2O and CO2 ice will be discussed, and the implications for planetary science missions will be considered. References: Gerakines, P. A., Hudson, R. L., Moore, M. H., and Bell, J-L. (2012). In-situ Measurements of the Radiation Stability of Amino Acids at 15 - 140 K. Icarus, 220, 647-659. Gerakines, P. A. and Hudson, R. L. (2013). Glycine's Radiolytic Destruction in Ices: First in situ Laboratory Measurements for Mars. Astrobiology, 13, 647-655.

  9. Crystal structures of NiSO4·9H2O and NiSO4·8H2O: magnetic properties, stability with respect to morenosite (NiSO4·7H2O), the solid-solution series (Mg x Ni1-x )SO4·9H2O

    Science.gov (United States)

    Fortes, A. D.; Knight, K. S.; Gibbs, A. S.; Wood, I. G.

    2018-02-01

    Since being discovered initially in mixed-cation systems, a method of forming end-member NiSO4·9H2O and NiSO4·8H2O has been found. We have obtained powder diffraction data from protonated analogues (with X-rays) and deuterated analogues (using neutrons) of these compounds over a range of temperatures, allowing us to determine their crystal structures—including all H-atoms—and to characterise the transitions on warming from 220 to 278 K; glass → 9-hydrate → 8-hydrate + ice → 7-hydrate + ice → partial melt (7-hydrate + liquid). NiSO4·8D2O is triclinic, space-group P\\bar {1} , Z = 2, with unit cell parameters at 150 K, a = 6.12463(8) Å, b = 6.8401(1) Å, c = 12.5339(2) Å, α = 92.846(1)°, β = 97.822(1)°, γ = 96.627(1)° and V = 515.58(1) Å3. The structure consists of two symmetry-inequivalent Ni(D2O)6 octahedra on sites of \\bar {1} symmetry. These are directly joined by a water-water H-bond to form chains of octahedra parallel with the c-axis at x = 0. Two interstitial water molecules serve both to bridge the Ni(D2O)6 octahedral chains in the b-c plane and also to connect with the SO4 2- tetrahedral oxyanion. These tetrahedra are linked by the two interstitial water molecules in a reticular motif to form sheets perpendicular to c. NiSO4·9D2O is monoclinic, space-group P21/c, Z = 4, with unit-cell parameters at 150 K, a = 6.69739(6) Å, b = 11.8628(1) Å, c = 14.5667(1) Å, β = 94.9739(8)° and V = 1152.96(1) Å3. The structure is isotypic with the Mg analogue described elsewhere (Fortes et al., Acta Cryst B 73:47‒64, 2017b). It shares the motif of H-bonded octahedral chains with NiSO4·8D2O, although in the enneahydrate these run parallel with the b-axis at x = 0. Three interstitial water molecules bridge the Ni(D2O)6 octahedra to the SO4 2- tetrahedral oxyanion. The tetrahedra sit at x ≈ 0.5 and are linked by two of the three interstitial water molecules in a pentagonal motif to form ribbons parallel with b. A solid-solution series

  10. Total cross sections for slow-electron (1--20 eV) scattering in solid H2O

    International Nuclear Information System (INIS)

    Michaud, M.; Sanche, L.

    1987-01-01

    An analytical method is proposed to determine absolute total cross sections per scatterer and related mean free paths for low-energy electron scattering in disordered molecular solid films. The procedure is based on a two-stream multiple-scattering model of the thickness dependence of the film reflectivity for elastic electrons. The expected analytical behavior and accuracy are tested on a model sample whose scattering properties are generated by a Monte Carlo simulation from initially known parameters. The effects of multiple scattering inside the film and at its interfaces are taken into account and discussed. The thickness dependence of the elastic electron reflectivity of H 2 O film condensed at 14 K is reported between 1 and 20 eV incident energy with a spectrometer resolution of 10 MeV. The proposed method is applied to extract from these measurements the energy dependence of the total effective and total inelastic cross sections for electron scattering in amorphous ice

  11. Brief communication: ikaite (CaCO3*6H2O) discovered in Arctic sea ice

    Science.gov (United States)

    Dieckmann, G. S.; Nehrke, G.; Uhlig, C.; Göttlicher, J.; Gerland, S.; Granskog, M. A.; Thomas, D. N.

    2010-02-01

    We report for the first time on the discovery of calcium carbonate crystals as ikaite (CaCO3*6H2O) in sea ice from the Arctic (Kongsfjorden, Svalbard). This finding demonstrates that the precipitation of calcium carbonate during the freezing of sea ice is not restricted to the Antarctic, where it was observed for the first time in 2008. This finding is an important step in the quest to quantify its impact on the sea ice driven carbon cycle and should in the future enable improvement parametrization sea ice carbon models.

  12. Brief Communication: Ikaite (CaCO3·6H2O discovered in Arctic sea ice

    Directory of Open Access Journals (Sweden)

    M. A. Granskog

    2010-05-01

    Full Text Available We report for the first time on the discovery of calcium carbonate crystals as ikaite (CaCO3·6H2O in sea ice from the Arctic (Kongsfjorden, Svalbard as confirmed by morphology and indirectly by X-ray diffraction as well as XANES spectroscopy of its amorophous decomposition product. This finding demonstrates that the precipitation of calcium carbonate during the freezing of sea ice is not restricted to the Antarctic, where it was observed for the first time in 2008. This observation is an important step in the quest to quantify its impact on the sea ice driven carbon cycle.

  13. Brief Communication: Ikaite (CaCO3·6H2O) discovered in Arctic sea ice

    Science.gov (United States)

    Dieckmann, G. S.; Nehrke, G.; Uhlig, C.; Göttlicher, J.; Gerland, S.; Granskog, M. A.; Thomas, D. N.

    2010-05-01

    We report for the first time on the discovery of calcium carbonate crystals as ikaite (CaCO3·6H2O) in sea ice from the Arctic (Kongsfjorden, Svalbard) as confirmed by morphology and indirectly by X-ray diffraction as well as XANES spectroscopy of its amorophous decomposition product. This finding demonstrates that the precipitation of calcium carbonate during the freezing of sea ice is not restricted to the Antarctic, where it was observed for the first time in 2008. This observation is an important step in the quest to quantify its impact on the sea ice driven carbon cycle.

  14. The Cheshire-cat-like Behavior of 2nu(sub 3) Overtone of Co2 near 2.134 micron: NIR Lab Spectra of Solid CO2 in H2O and CH3OH

    Science.gov (United States)

    Bernstein, Max; Sandford, Scott; Cruikshank, Dale

    2005-01-01

    Infrared (IR) spectra have demonstrated that solid H2O is very common in the outer Solar System, and solid carbon dioxide (CO2) has been detected on icy satellites, comets, and planetismals throughout the outer Solar System. In such environments, CO2 and H2O must sometimes be mixed at a molecular level, changing their IR absorption features. In fact, the IR spectra of CO2-H2O mixtures are not equivalent to a linear combination of the spectra of the pure materials. Laboratory IR spectra of pure CO2 and H2O have been published but a lack of near-IR spectra of CO2-H2O mixtures has made the interpretation of outer Solar System spectra more difficult. We present near infrared (IR) spectra of CO2 in H2O and in CH3OH compared to that of pure solid CO2 and find significant differences. Peaks not present in either pure H2O or pure CO2 spectra become evident. First, the CO2 (2nu(sub 3)) overtone near 2.134 micron (4685/ cm) that is not seen in pure solid CO2 is prominent in the spectrum of a CO2/H2O = 25 mixture. Second, a 2.74 micron (3650/ cm) dangling OH feature of water (and a potentially related peak at 1.89 micron) appear in the spectra of CO2-H2O ice mixtures, but may not be specific to the presence of CO2. Other CO2 peaks display shifts in position and increased width because of intermolecular interactions with water. Changes in CO2 peak positions and profiles on warming of a CO2/H2O = 5 mixture are consistent with 'segregation' of the ice into nearly pure separate components. Absolute strengths for absorptions of CO2 in solid H2O are estimated. Similar results are observed for CO2 in solid CH3OH. Since the CO2 ( 2nu(sub 3)) overtone near 2.134 micron (4685/ cm) is not present in pure CO2 but prominent in mixtures it may be a good observational indicator of whether solid CO2 is a pure material or intimately mixed with other molecules. Significant changes in the near IR spectrum of solid CO2 in the presence of H2O and CH3OH means that the abundance of solid CO2 in the

  15. SYSTEMATIC VARIATIONS IN CO2/H2O ICE ABUNDANCE RATIOS IN NEARBY GALAXIES FOUND WITH AKARI NEAR-INFRARED SPECTROSCOPY

    International Nuclear Information System (INIS)

    Yamagishi, M.; Kaneda, H.; Ishihara, D.; Oyabu, S.; Onaka, T.; Shimonishi, T.; Suzuki, T.

    2015-01-01

    We report CO 2 /H 2 O ice abundance ratios in seven nearby star-forming galaxies based on the AKARI near-infrared (2.5–5.0 μm) spectra. The CO 2 /H 2 O ice abundance ratios show clear variations between 0.05 and 0.2 with the averaged value of 0.14 ± 0.01. The previous study on M82 revealed that the CO 2 /H 2 O ice abundance ratios strongly correlate with the intensity ratios of the hydrogen recombination Brα line to the polycyclic aromatic hydrocarbon (PAH) 3.3 μm feature. In the present study, however, we find no correlation for the seven galaxies as a whole due to systematic differences in the relation between CO 2 /H 2 O ice abundance and Brα/PAH 3.3 μm intensity ratios from galaxy to galaxy. This result suggests that there is another parameter that determines the CO 2 /H 2 O ice abundance ratios in a galaxy in addition to the Brα/PAH 3.3 μm ratios. We find that the CO 2 /H 2 O ice abundance ratios positively correlate with the specific star formation rates of the galaxies. From these results, we conclude that CO 2 /H 2 O ice abundance ratios tend to be high in young star-forming galaxies

  16. Visible and ultraviolet emission from pulse irradiated amorphous and polycrystalline H2O ice

    International Nuclear Information System (INIS)

    Freeman, C.G.; Quickenden, T.I.; Litjens, R.A.J.; Sangster, D.F.

    1984-01-01

    Luminescence peaking at 405 nm was observed when thin films of amorphous or polycrystalline ice at 97 K were irradiated with a pulsed beam of 0.53 MeV electrons. These emissions differed from the luminescence emitted by crystalline ice in that memory effects were not observed; the peak wavelengths were red shifted by approx.20 nm; and the half-lives were 6--9 ns instead of approx.400 ns. The emission spectra of polycrystalline ice samples produced by rapid deposition or by annealing amorphous ice were similar, but both had substantially lower intensities than amorphous ice spectra

  17. Alteration of the UV-visible reflectance spectra of H2O ice by ion bombardment

    Science.gov (United States)

    Sack, N. J.; Boring, J. W.; Johnson, R. E.; Baragiola, R. A.; Shi, M.

    1991-01-01

    Satellite in the Jovian and Saturnian system exhibit differences in reflectivity between their 'leading' and 'trailing' surfaces which can affect the local vapor pressure. Since these differences are thought to be due to differences in the flux of bombarding magnetospheric ions, the influence of ion impact on the UV-visible reflectance of water ice surfaces (20-90 K) by keV ion bombardment was studied. An observed decrease in reflectance in the UV is attributed to rearrangement processes that affect the physical microstructure and surface 'roughness'. The ratio in reflectance of bombarded to freshly deposited films is compared to the ratio of the reflectance of the leading and trailing hemispheres for Europa and Ganymede.

  18. Kinetics of oxidation of H2 and reduction of H2O in Ni-YSZ based solid oxide cells

    DEFF Research Database (Denmark)

    Ebbesen, Sune Dalgaard; Mogensen, Mogens Bjerg

    2012-01-01

    Reduction of H2O and oxidation of H2 was studied in a Ni-YSZ electrode supported Solid Oxide Cells produced at DTU Energy conversion (former Risø DTU). Polarisation (i-V) and electrochemical impedance spectroscopic characterisation show that the kinetics for reduction of H 2O is slower compared...... to oxidation of H2. The kinetic differences cannot be explained by the reaction mechanisms which are similar in the two cases but are rather an effect of the thermodynamics. The preliminary analysis performed in this study show that the slow kinetic for reduction is partly related to the endothermic nature...... of the reaction, cooling the active electrode, thereby leading to slower kinetics at low current densities. Likewise, the increased kinetic for oxidation was found to be related to the exothermic nature of the reaction, heating the active electrode, and thereby leading to faster kinetics. At higher current...

  19. Novel two-step laser ablation and ionization mass spectrometry (2S-LAIMS) of actor-spectator ice layers: Probing chemical composition of D2O ice beneath a H2O ice layer

    International Nuclear Information System (INIS)

    Yang, Rui; Gudipati, Murthy S.

    2014-01-01

    In this work, we report for the first time successful analysis of organic aromatic analytes imbedded in D 2 O ices by novel infrared (IR) laser ablation of a layered non-absorbing D 2 O ice (spectator) containing the analytes and an ablation-active IR-absorbing H 2 O ice layer (actor) without the analyte. With these studies we have opened up a new method for the in situ analysis of solids containing analytes when covered with an IR laser-absorbing layer that can be resonantly ablated. This soft ejection method takes advantage of the tenability of two-step infrared laser ablation and ultraviolet laser ionization mass spectrometry, previously demonstrated in this lab to study chemical reactions of polycyclic aromatic hydrocarbons (PAHs) in cryogenic ices. The IR laser pulse tuned to resonantly excite only the upper H 2 O ice layer (actor) generates a shockwave upon impact. This shockwave penetrates the lower analyte-containing D 2 O ice layer (spectator, a non-absorbing ice that cannot be ablated directly with the wavelength of the IR laser employed) and is reflected back, ejecting the contents of the D 2 O layer into the vacuum where they are intersected by a UV laser for ionization and detection by a time-of-flight mass spectrometer. Thus, energy is transmitted from the laser-absorbing actor layer into the non-absorbing spectator layer resulting its ablation. We found that isotope cross-contamination between layers was negligible. We also did not see any evidence for thermal or collisional chemistry of PAH molecules with H 2 O molecules in the shockwave. We call this “shockwave mediated surface resonance enhanced subsurface ablation” technique as “two-step laser ablation and ionization mass spectrometry of actor-spectator ice layers.” This method has its roots in the well-established MALDI (matrix assisted laser desorption and ionization) method. Our method offers more flexibility to optimize both the processes—ablation and ionization. This new technique

  20. Release of N 2, CH 4, CO 2, and H 2O from surface ices on Enceladus

    Science.gov (United States)

    Hodyss, Robert; Goguen, Jay D.; Johnson, Paul V.; Campbell, Colin; Kanik, Isik

    2008-09-01

    We vapor deposit at 20 K a mixture of gases with the specific Enceladus plume composition measured in situ by the Cassini INMS [Waite, J.H., Combi, M.R., Ip, W.H., Cravens, T.E., McNutt, R.L., Kasprzak, W., Yelle, R., Luhmann, J., Niemann, H., Gell, D., Magee, B., Fletcher, G., Lunine, J., Tseng, W.L., 2006. Science 311, 1419-1422] to form a mixed molecular ice. As the sample is slowly warmed, we monitor the escaping gas quantity and composition with a mass spectrometer. Pioneering studies [Schmitt, B., Klinger, J., 1987. Different trapping mechanisms of gases by water ice and their relevance for comet nuclei. In: Rolfe, E.J., Battrick, B. (Eds.), Diversity and Similarity of Comets. SP-278. ESA, Noordwijk, The Netherlands, pp. 613-619; Bar-Nun, A., Kleinfeld, I., Kochavi, E., 1988. Phys. Rev. B 38, 7749-7754; Bar-Nun, A., Kleinfeld, I., 1989. Icarus 80, 243-253] have shown that significant quantities of volatile gases can be trapped in a water ice matrix well above the temperature at which the pure volatile ice would sublime. For our Enceladus ice mixture, a composition of escaping gases similar to that detected by Cassini in the Enceladus plume can be generated by the sublimation of the H 2O:CO 2:CH 4:N 2 mixture at temperatures between 135 and 155 K, comparable to the high temperatures inferred from the CIRS measurements [Spencer, J.R., Pearl, J.C., Segura, M., Flasar, F.M., Mamoutkine, A., Romani, P., Buratti, B.J., Hendrix, A.R., Spilker, L.J., Lopes, R.M.C., 2006. Science 311, 1401-1405] of the Enceladus "tiger stripes." This suggests that the gas escape phenomena that we measure in our experiments are an important process contributing to the gases emitted from Enceladus. A similar experiment for ice deposited at 70 K shows that both the processes of volatile trapping and release are temperature dependent over the temperature range relevant to Enceladus.

  1. The study of ikaite (CaCO3·6H2O) formation and its impact on biogeochemical processes in artificial sea ice brine

    OpenAIRE

    Hu, Yubin

    2014-01-01

    Calcium carbonate precipitation in polar sea ice has been proposed as one of the driving forces for the carbon pump in sea ice covered regions. After decades of controversial discussion on whether calcium carbonate can be precipitated in sea ice, the mineral ikaite (CaCO3·6H2O) was for the first time discovered in Antarctic sea ice (Dieckmann et al., 2008) and later also found in Arctic sea ice (Dieckmann et al., 2010). However, the mechanism of ikaite precipitation in sea ice is not well kno...

  2. Solid-liquid phase equilibrium in the systems of LiBr-H2O and LiCl-H2O

    Czech Academy of Sciences Publication Activity Database

    Pátek, Jaroslav; Klomfar, Jaroslav

    2006-01-01

    Roč. 250, - (2006), s. 138-149 ISSN 0378-3812 Institutional research plan: CEZ:AV0Z20760514 Keywords : salt-water system * solubility * solid-liquid system * lithium bromide * litthium chloride Subject RIV: BJ - Thermodynamics Impact factor: 1.680, year: 2006

  3. Carbon Deposition in Solid Oxide Cells during Co-Electrolysis of H2O and CO2

    DEFF Research Database (Denmark)

    Tao, Youkun; Ebbesen, Sune Dalgaard; Mogensen, Mogens Bjerg

    2014-01-01

    current densities from 1.5 to 2.25 A/cm2 and reactant (H2O + CO2) conversion of up to 67%. Delamination and carbon nano-fibers were observed at the Ni-YSZ|YSZ interface for two cells with a dense microstructure operated at electrolysis current densities of 2.0 and 2.25 A/cm2 and a conversion of 59% and 67...... and the active Ni-YSZ electrode. Carbon nano-fibers were only observed close to the YSZ electrolyte, indicating a very reducing atmosphere and a large over-potential gradient in the active electrode, being highest at the interface to the bulk electrolyte and decreasing toward the Ni-YSZ support.......Carbon formation during co-electrolysis of H2O and CO2 in Ni-YSZ supported Solid Oxide Electrolysis Cells (SOECs) may occur, especially at high current density and high conversion. In order to evaluate the carbon formation limits, five galvanostatic tests were performed in this work at electrolysis...

  4. ZnO nanoneedle/H2O solid-liquid heterojunction-based self-powered ultraviolet detector

    Science.gov (United States)

    2013-01-01

    ZnO nanoneedle arrays were grown vertically on a fluorine-doped tin oxide-coated glass by hydrothermal method at a relatively low temperature. A self-powered photoelectrochemical cell-type UV detector was fabricated using the ZnO nanoneedles as the active photoanode and H2O as the electrolyte. This solid-liquid heterojunction offers an enlarged ZnO/water contact area and a direct pathway for electron transport simultaneously. By connecting this UV photodetector to an ammeter, the intensity of UV light can be quantified using the output short-circuit photocurrent without a power source. High photosensitivity, excellent spectral selectivity, and fast photoresponse at zero bias are observed in this UV detector. The self-powered behavior can be well explained by the formation of a space charge layer near the interface of the solid-liquid heterojunction, which results in a built-in potential and makes the solid-liquid heterojunction work in photovoltaic mode. PMID:24103153

  5. Characterization of ikaite (CaCO3•6H2O) crystals in first year Arctic sea ice north of Svalbard

    OpenAIRE

    Nomura, Daiki; Assmy, Philipp; Nehrke, Gernot; Granskog, Mats A.; Fischer, Michael; Dieckmann, Gerhard; Fransson, Agneta; Hu, Yubin; Schnetger, Bernhard

    2013-01-01

    We identified ikaite crystals (CaCO3·6H2O) and examined their shape and size distribution in first-year Arctic pack ice, overlying snow and slush layers during the spring melt onset north of Svalbard. Additional measurements of total alkalinity (TA) were made for melted snow and sea-ice samples. Ikaite crystals were mainly found in the bottom of the snowpack, in slush and the surface layers of the sea ice where the temperature was generally lower and salinity higher than in the ic...

  6. Modeling CO, CO2, and H2O Ice Abundances in the Envelopes of Young Stellar Objects in the Magellanic Clouds

    Science.gov (United States)

    Pauly, Tyler; Garrod, Robin T.

    2018-02-01

    Massive young stellar objects (MYSOs) in the Magellanic Clouds show infrared absorption features corresponding to significant abundances of CO, CO2, and H2O ice along the line of sight, with the relative abundances of these ices differing between the Magellanic Clouds and the Milky Way. CO ice is not detected toward sources in the Small Magellanic Cloud, and upper limits put its relative abundance well below sources in the Large Magellanic Cloud and the Milky Way. We use our gas-grain chemical code MAGICKAL, with multiple grain sizes and grain temperatures, and further expand it with a treatment for increased interstellar radiation field intensity to model the elevated dust temperatures observed in the MCs. We also adjust the elemental abundances used in the chemical models, guided by observations of H II regions in these metal-poor satellite galaxies. With a grid of models, we are able to reproduce the relative ice fractions observed in MC MYSOs, indicating that metal depletion and elevated grain temperature are important drivers of the MYSO envelope ice composition. Magellanic Cloud elemental abundances have a subgalactic C/O ratio, increasing H2O ice abundances relative to the other ices; elevated grain temperatures favor CO2 production over H2O and CO. The observed shortfall in CO in the Small Magellanic Cloud can be explained by a combination of reduced carbon abundance and increased grain temperatures. The models indicate that a large variation in radiation field strength is required to match the range of observed LMC abundances. CH3OH abundance is found to be enhanced in low-metallicity models, providing seed material for complex organic molecule formation in the Magellanic Clouds.

  7. Water Ice Radiolytic O2, H2, and H2O2 Yields for Any Projectile Species, Energy, or Temperature: A Model for Icy Astrophysical Bodies

    Science.gov (United States)

    Teolis, B. D.; Plainaki, C.; Cassidy, T. A.; Raut, U.

    2017-10-01

    O2, H2, and H2O2 radiolysis from water ice is pervasive on icy astrophysical bodies, but the lack of a self-consistent, quantitative model of the yields of these water products versus irradiation projectile species and energy has been an obstacle to estimating the radiolytic oxidant sources to the surfaces and exospheres of these objects. A major challenge is the wide variation of O2 radiolysis yields between laboratory experiments, ranging over 4 orders of magnitude from 5 × 10-7 to 5 × 10-3 molecules/eV for different particles and energies. We revisit decades of laboratory data to solve this long-standing puzzle, finding an inverse projectile range dependence in the O2 yields, due to preferential O2 formation from an 30 Å thick oxygenated surface layer. Highly penetrating projectile ions and electrons with ranges ≳30 Å are therefore less efficient at producing O2 than slow/heavy ions and low-energy electrons (≲ 400 eV) which deposit most energy near the surface. Unlike O2, the H2O2 yields from penetrating projectiles fall within a comparatively narrow range of (0.1-6) × 10-3 molecules/eV and do not depend on range, suggesting that H2O2 forms deep in the ice uniformly along the projectile track, e.g., by reactions of OH radicals. We develop an analytical model for O2, H2, and H2O2 yields from pure water ice for electrons and singly charged ions of any mass and energy and apply the model to estimate possible O2 source rates on several icy satellites. The yields are upper limits for icy bodies on which surface impurities may be present.

  8. Interaction of D2 with H2O amorphous ice studied by temperature-programmed desorption experiments.

    Science.gov (United States)

    Amiaud, L; Fillion, J H; Baouche, S; Dulieu, F; Momeni, A; Lemaire, J L

    2006-03-07

    The gas-surface interaction of molecular hydrogen D2 with a thin film of porous amorphous solid water (ASW) grown at 10 K by slow vapor deposition has been studied by temperature-programmed-desorption (TPD) experiments. Molecular hydrogen diffuses rapidly into the porous network of the ice. The D2 desorption occurring between 10 and 30 K is considered here as a good probe of the effective surface of ASW interacting with the gas. The desorption kinetics have been systematically measured at various coverages. A careful analysis based on the Arrhenius plot method has provided the D2 binding energies as a function of the coverage. Asymmetric and broad distributions of binding energies were found, with a maximum population peaking at low energy. We propose a model for the desorption kinetics that assumes a complete thermal equilibrium of the molecules with the ice film. The sample is characterized by a distribution of adsorption sites that are filled according to a Fermi-Dirac statistic law. The TPD curves can be simulated and fitted to provide the parameters describing the distribution of the molecules as a function of their binding energy. This approach contributes to a correct description of the interaction of molecular hydrogen with the surface of possibly porous grain mantles in the interstellar medium.

  9. ULTRAVIOLET PHOTON-INDUCED SYNTHESIS AND TRAPPING OF H2O2 AND O3 IN POROUS WATER ICE FILMS IN THE PRESENCE OF AMBIENT O2: IMPLICATIONS FOR EXTRATERRESTRIAL ICE

    International Nuclear Information System (INIS)

    Shi, J.; Raut, U.; Kim, J.-H.; Baragiola, R. A.; Loeffler, M.

    2011-01-01

    The mass uptake of ambient oxygen in nanoporous ice is enhanced by irradiation with 193 nm photons, due to conversion of O 2 into H 2 O 2 and O 3 , with an efficiency that increases with decreasing temperature. These findings show a new way to form H 2 O 2 and O 3 on icy surfaces in the outer solar system at depths much larger than are accessible by typical ionizing radiation, with possible astrobiological implications.

  10. Solid solutions in the system Nd2(SeO4)3 - Sm2(SeO4)3 - H2O

    International Nuclear Information System (INIS)

    Serebrennikov, V.V.; Tsybukova, T.N.; Velikov, A.A.

    1984-01-01

    Using the method of isothermal solubility at 25 deg C the system Nd 2 (SeO 4 ) 3 -Sm 2 (SeO 4 ) 3 -H 2 O has been studied. Roentgenographic recording of solid ''residues'' is realized. For solid solutions energies of interchange and formation heats are calculated. Formation heats of solid solutions on the basis of samarium selenates are also found experimentally

  11. Synthesis and regulation of α-LiZnPO4.H2O via a solid-state reaction at low-heating temperatures

    International Nuclear Information System (INIS)

    Liao Sen; Chen Zhipeng; Tian Xiaozhen; Wu Wenwei

    2009-01-01

    A simple and novel route for the synthesis of a lithium zinc phosphate hydrate, α-LiZnPO 4 .H 2 O, was studied, and the target product was obtained with LiH 2 PO 4 .H 2 O and ZnCO 3 as raw materials and polyethylene glycol-400 (PEG-400) as a surfactant via a one step solid-state reaction at room temperature (25 deg. C). The product was characterized with X-ray powder diffraction (XRD), thermogravimetric analysis and the 1st derivativative of thermogravimetric analysis (TG/DTG) and Fourier transform infrared spectroscopy (FTIR). The comparison experimental results suggested that aging temperature controlled the products of the synthesis, that is, the α-LiZnPO 4 .H 2 O was formed when the reaction mixture was aged at room temperature, and the α-LiZnPO 4 was obtained when the reaction mixture was aged at 80 deg. C.

  12. Thermodynamic Study of Solid-Liquid Equilibrium in NaCl-NaBr-H2O System at 288.15 K

    Science.gov (United States)

    Li, Dan; Meng, Ling-zong; Deng, Tian-long; Guo, Ya-fei; Fu, Qing-Tao

    2018-06-01

    The solubility data, composition of the solid solution and refractive indices of the NaCl-NaBr-H2O system at 288.15 K were studied with the isothermal equilibrium dissolution method. The solubility diagram and refractive index diagram of this system were plotted at 288.15 K. The solubility diagram consists of two crystallization zones for solid solution Na(Cl,Br) · 2H2O and Na(Cl,Br), one invariant points cosaturated with two solid solution and two univariant solubility isothermal curves. On the basis of Pitzer and Harvie-Weare (HW) chemical models, the composition equations and solubility equilibrium constant equations of the solid solutions at 288.15 K were acquired using the solubility data, the composition of solid solutions, and binary Pitzer parameters. The solubilities calculated using the new method combining the equations are in good agreement with the experimental data.

  13. Possible significance of cubic water-ice, H2O-Ic, in the atmospheric water cycle of Mars

    Science.gov (United States)

    Gooding, James L.

    1988-01-01

    The possible formation and potential significance of the cubic ice polymorph on Mars is discussed. When water-ice crystallizes on Earth, the ambient conditions of temperature and pressure result in the formation of the hexagonal ice polymorph; however, on Mars, the much lower termperature and pressures may permit the crystallization of the cubic polymorph. Cubic ice has two properties of possible importance on Mars: it is an excellant nucleator of other volatiles (such as CO2), and it undergoes an exothermic transition to hexagonal ice at temperatures above 170 K. These properties may have significant implications for both martian cloud formation and the development of the seasonal polar caps.

  14. Ice Lens Formation, Frost Heave, Thin Films, and the Importance of the Polar H2O Reservoir at High Obliquity

    Science.gov (United States)

    Zent, A. P.; Sizemore, H. G.; Rempel, A. W.

    2011-01-01

    Several lines of evidence indicate that the volume of shallow ground ice in the martian high latitudes exceeds the pore volume of the host regolith. Boynton et al. found an optimal fit to the Mars Odyssey Gamma Ray Spectrometer (GRS) data at the Phoenix landing site by modeling a buried layer of 50-75% ice by mass (up to 90% ice by volume). Thermal and optical observations of recent impact craters in the northern hemisphere have revealed nearly pure ice. Ice deposits containing only 1-2% soil by volume were excavaged by Phoenix. One hypothesis for the origin of this excess ice is that it developed in situ by a mechanism analogous to the formation of terrestrial ice lenses and needle ice. Problematically, terrestrial soil-ice segregation is driven by freeze/thaw cycling and the movement of bulk water, neither of which are expected to have occurred in the geologically recent past on Mars. If however ice lens formation is possible at temperatures less than 273 K, there are possible implications for the habitability of Mars permafrost, since the same thin films of unfrozen water that lead to ice segregation are used by terrestrial psychrophiles to metaboluze and grow down to temperatures of at least 258 K.

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

    Science.gov (United States)

    Hudson, Reggie L.; Loeffler, Mark J.

    2012-01-01

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

  16. Mechanism for the abiotic synthesis of uracil via UV-induced oxidation of pyrimidine in pure H2O ices under astrophysical conditions

    International Nuclear Information System (INIS)

    Bera, Partha P.; Nuevo, Michel; Sandford, Scott A.; Lee, Timothy J.; Milam, Stefanie N.

    2010-01-01

    The UV photoirradiation of pyrimidine in pure H 2 O ices has been explored using second-order Moeller-Plesset perturbation theory and density functional theory methods, and compared with experimental results. Mechanisms studied include those starting with neutral pyrimidine or cationic pyrimidine radicals, and reacting with OH radical. The ab initio calculations reveal that the formation of some key species, including the nucleobase uracil, is energetically favored over others. The presence of one or several water molecules is necessary in order to abstract a proton which leads to the final products. Formation of many of the photoproducts in UV-irradiated H 2 O:pyrimidine=20:1 ice mixtures was established in a previous experimental study. Among all the products, uracil is predicted by quantum chemical calculations to be the most favored, and has been identified in experimental samples by two independent chromatography techniques. The results of the present study strongly support the scenario in which prebiotic molecules, such as the nucleobase uracil, can be formed under abiotic processes in astrophysically relevant environments, namely in condensed phase on the surface of icy, cold grains before being delivered to the telluric planets, like Earth.

  17. (Solid + liquid) phase equilibria of (Ca(H2PO2)2 + CaCl2 + H2O) and (Ca(H2PO2)2 + NaH2PO2 + H2O) ternary systems at T = 323.15 K

    International Nuclear Information System (INIS)

    Cao, Hong-yu; Zhou, Huan; Bai, Xiao-qin; Ma, Ruo-xin; Tan, Li-na; Wang, Jun-min

    2016-01-01

    Graphical abstract: Solubility diagram of the (Ca(H 2 PO 2 ) 2 + NaH 2 PO 2 + H 2 O) system at T = (323.15 and 298.15) K. - Highlights: • Phase diagrams of Ca 2+ -H 2 PO 2 − -Cl − -H 2 O, Ca 2+ -Na + -H 2 PO 2 − -H 2 O at 323.15 K were obtained. • Incompatible double salt of NaCa(H 2 PO 2 ) 3 in Ca 2+ -Na + -H 2 PO 2 − -H 2 O system was determined. • Density diagram of the corresponding liquid were simultaneously measured. - Abstract: Calcium hypophosphite has been widely used as an anti-corrosive agent, flame retardant, fertilizer, assistant for Ni electroless plating, and animal nutritional supplement. High purity calcium hypophosphite can be synthesized via the replacement reaction of sodium hypophosphite and calcium chloride. In this work, the (solid + liquid) phase equilibria of (Ca(H 2 PO 2 ) 2 + CaCl 2 + H 2 O) and (Ca(H 2 PO 2 ) 2 + NaH 2 PO 2 + H 2 O) ternary systems at T = 323.15 K were studied experimentally via the classical isothermal solubility equilibrium method, and the phase diagrams for these two systems were obtained. It was found that two solid salts of CaCl 2 ·2H 2 O and Ca(H 2 PO 2 ) 2 exist in the (Ca(H 2 PO 2 ) 2 + CaCl 2 + H 2 O) system, and three salts of Ca(H 2 PO 2 ) 2 , NaH 2 PO 2 ·H 2 O and one incompatible double salt, NaCa(H 2 PO 2 ) 3 occur in the (Ca(H 2 PO 2 ) 2 + NaH 2 PO 2 + H 2 O) system.

  18. Following the south polar cap recession as viewed by OMEGA/MEX using automatic detection of H2O and CO2 ices.

    Science.gov (United States)

    Schmidt, F.; Doute, S.; Schmitt, B.

    In order to understand Mars' current climate it is necessary to detect, characterize and monitor CO2 and H2O at the surface (permanent and seasonal icy deposits) and in the atmosphere (vapor and clouds). Here we will focus on the South Seasonal Polar Cap (SSPC) whose recession was previously observed with different techniques : from earth in the visible range with HST [James 1996], or from MGS spacecraft with MOC images [Benson 2005], in the thermal IR range by the TES [Kieffer 2000], in the near infrared by OMEGA/MEX [Langevin submitted]. The time and space evolutions of the SSPC is a major annual climatic signal both at the global and the regional scales. In particular the measurement of the temporal and spatial distributions of CO2 constrains exchange processes between both surface and atmosphere. This exchange may involve preponderant species : H2O, CO2 and dust. In this work we will apply a new detection technique : "wavanglet" in order to follow the recession of the SSPC thanks to OMEGA/MEX observations. This method was especially developed in the goal to classify a huge dataset, such OMEGA ones. We propose to use "wavanglet" as a supervised automatic classification method that identifies spectral features and classifies the image in spectrally homogeneous units. Additionally we will evaluate quantitative detection limits of "wavanglet" based on synthetic dataset simulating OMEGA spectra in typical situation of the SSPC. This detection limit will be discussed in terms of abundance for H2O and CO2 ices in order to improve the interpretation of the classification. Finally we will present the recession of the SSPC using "wavanglet" and we will compare the results with those of earlier investigation. An interpretation of the similarities and disagreements between those maps will be done.

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

    Science.gov (United States)

    Loeffler, Mark Josiah; Hudson, Reggie Lester

    2015-01-01

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

  20. Discovery of moganite in a lunar meteorite as a trace of H2O ice in the Moon’s regolith

    Science.gov (United States)

    Seto, Yusuke; Miyake, Akira; Sekine, Toshimori; Tomeoka, Kazushige; Matsumoto, Megumi; Kobayashi, Takamichi

    2018-01-01

    Moganite, a monoclinic SiO2 phase, has been discovered in a lunar meteorite. Silica micrograins occur as nanocrystalline aggregates of mostly moganite and occasionally coesite and stishovite in the KREEP (high potassium, rare-earth element, and phosphorus)–like gabbroic-basaltic breccia NWA 2727, although these grains are seemingly absent in other lunar meteorites. We interpret the origin of these grains as follows: alkaline water delivery to the Moon via carbonaceous chondrite collisions, fluid capture during impact-induced brecciation, moganite precipitation from the captured H2O at pH 9.5 to 10.5 and 363 to 399 K on the sunlit surface, and meteorite launch from the Moon caused by an impact at 8 to 22 GPa and >673 K. On the subsurface, this captured H2O may still remain as ice at estimated bulk content of >0.6 weight %. This indicates the possibility of the presence of abundant available water resources underneath local sites of the host bodies within the Procellarum KREEP and South Pole Aitken terranes. PMID:29732406

  1. The solid state radiolysis of the H2O/DMSO binary system. The origin of the radiobiological damage of cells in cryostatic conditions

    International Nuclear Information System (INIS)

    Dondi, D.; Buttafava, A.; Faucitano, A.; Cherubini, R.; De Nadal, V.; Gerardi, S.

    2011-01-01

    Complete text of publication follows. The cryoconservation method is based on the use of cryogenic fluids which, when mixed with water, partially protect the cells from the segregation of salts. During a long period of storage in the cryogenic state, the radiation dose from the natural background can attain a dose of 0.1 Gy in 25-50 y. which can be the source of significant mutagenic effects. The present work deals with the EPR study of the γ-radiolysis at 77 K of the binary system H 2 O/DMSO which is the most commonly used freezing medium. The free radical yields and decay kinetics were determined for DMSO/H 2 O frozen mixtures of composition ranging from pure water to pure DMSO, passing through the key 10% DMSO composition. The radical vs dose yield curves were observed to pass through a maximum in correspondence of the DMSO x 3H 2 O hydrate. Radicals are trapped during the irradiation but are released on warming near the melting temperature; radical attack to cells structures can take place at this stage, provided that the reactants be in the same phase. The attitude of trapped radicals to interact on melting with organic substrates was tested by performing a set of experiments using the 2,2,6,6 tetramethyl piperidinyl oxyl stable radical as a spin trapping agent. An upper limit estimate of the fraction of trapped radicals potentially capable of causing radical damage on melting could thus be determined as a function of the H 2 O/DMSO ratio. This fraction is 14% for H 2 O/DMSO (10%) mixtures. OH radicals instead were found to be non-reactive probably because are trapped in separated ices phases. EPR measurements performed on irradiated H 2 O/DMSO (10%) frozen samples containing 1.5 x 10 7 cells/ml have shown that almost the totality of the trapped radicals are generated from the components of the freezing medium.

  2. N- AND O-HETEROCYCLES PRODUCED FROM THE IRRADIATION OF BENZENE AND NAPHTHALENE IN H2O/NH3-CONTAINING ICES

    International Nuclear Information System (INIS)

    Materese, Christopher K.; Nuevo, Michel; Sandford, Scott A.

    2015-01-01

    Aromatic heterocyclic molecules are an important class of molecules of astrophysical and biological significance that include pyridine, pyrimidine, and their derivatives. Such compounds are believed to exist in interstellar and circumstellar environments, though they have never been observed in the gas phase. Regardless of their presence in the gas phase in space, numerous heterocycles have been reported in carbonaceous meteorites, which indicates that they are formed under astrophysical conditions. The experimental work described here shows that N- and O-heterocyclic molecules can form from the ultraviolet (UV) irradiation of the homocyclic aromatic molecules benzene (C 6 H 6 ) or naphthalene (C 10 H 8 ) mixed in ices containing H 2 O and NH 3 . This represents an alternative way to generate aromatic heterocycles to those considered before and may have important implications for astrochemistry and astrobiology

  3. Preliminary 3D In-situ measurements of the texture evolution of strained H2O ice during annealing using neutron Laue diffractometry

    Science.gov (United States)

    Journaux, Baptiste; Montagnat, Maurine; Chauve, Thomas; Ouladdiaf, Bachir; Allibon, John

    2015-04-01

    Dynamic recrystallization (DRX) strongly affects the evolution of microstructure (grain size and shape) and texture (crystal preferred orientation) in materials during deformation at high temperature. Since texturing leads to anisotropic physical properties, predicting the effect of DRX is essential for industrial applications, for interpreting geophysical data and modeling geodynamic flows, and predicting ice sheet flow and climate evolution. A large amount of literature is available related to metallurgy, geology or glaciology, but there remains overall fundamental questions about the relationship between nucleation, grain boundary migration and texture development at the microscopic scale. Previous measurements of DRX in ice were either conducted using 2D ex-situ techniques such as AITA [1,2] or Electron Backscattering Diffraction (EBSD) [3], or using 3D statistical ex-situ [4] or in-situ [5] techniques. Nevertheless, all these techniques failed to observe at the scale of nucleation processes during DRX in full 3D. Here we present a new approach using neutron Laue diffraction, which enable to perform 3D measurements of in-situ texture evolution of strained polycrystalline H2O ice (>2% at 266 K) during annealing at the microscopic scale. Thanks the CYCLOPS instrument [6] (Institut Laue Langevin Grenoble, France) and the intrinsic low background of this setup, preliminary observations enabled us to follow, in H2O ice, the evolution of serrated grain boundaries, and kink-band during annealing. Our observations show a significant evolution of the texture and internal misorientation over the course of few hours at an annealing temperature of 268.5 K. In the contrary, ice kink-band structures seem to be very stable over time at near melting temperatures. The same samples have been analyzed ex-situ using EBSD for comparison. These results represent a first step toward in-situ microscopic measurements of dynamic recrystallization processes in ice during strain. This

  4. Liquids - vapor and liquids - solids equilibria in the system Th(NO3)4 - UO2(NO3)2 - HNO3 - H2O

    International Nuclear Information System (INIS)

    Volk, V.I.; Vakhrushin, A.Yu.; Mamaev, S.L.; Zhirnov, Yu.P.

    1999-01-01

    Liquids - vapor and liquids - solids equilibria in the system Th(NO 3 ) 4 - UO 2 (NO 3 ) 2 - HNO 3 - H 2 O were investigated. It was established that in this system thorium nitrate hexahydrate and uranyl nitrate hexa- and trihydrate are formed. Empiric equations of solubility isotherm at 25 deg C were found. Densities of liquid phases of the system were determined. It was established that uranyl nitrates and thorium nitrates salt out nitric acid in vapor phase just as separately so in the case of mutual presence. Empiric equation fixing relationship between nitric acid concentration in condensed phase and concentrations of all components in liquid phase was found

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

    Science.gov (United States)

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

    2013-01-01

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

  6. Characteristics of transfer of europium ions from phosphoric acid solution into the CaSO4·O.5H2O solid phase

    International Nuclear Information System (INIS)

    Berdonosova, D.G.; Burlakova, E.V.; Yasenkova, M.A.; Ivanov, L.N.; Melikhov, I.V.

    1989-01-01

    The mechanism of formation of the precipitated CaSO 4 ·0.5H 2 O phase was studied in detail; the precipitation was performed at 80 degree, equimolar solutions of Ca(H 2 PO 4 ) 2 and H 2 SO 4 in phosphoric acid of 38% concentration being used. The availability of detailed information on the mechanism of formation of CaSO 4 ·0.5H 2 O precipitates determined the choice of conditions of study of capture of rare earths. In particular, H 3 PO 4 of 38% P 2 O 5 concentration was used as the medium of formation of the calcium sulfate precipitate. Europium was chosen as the rare earth. Its behavior in the liquid and solid phases was studied by radiometric and luminescence methods. The radionuclide 152 Eu is convenient as a radioactive tracer while luminescence of europium is structure-sensitive; therefore, europium is often used in physicochemical investigations as a luminescent probe. It follows from the data that most of the europium captured by the precipitate during coagulation of the ultramicrocrystals is retained firmly by the solid phase. Therefore, in order to diminish capture of europium (and other rare earths) by the precipitate coagulation of the latter should be prevented

  7. Effect of coatings on long term behaviour of a commercial stainless steel for solid oxide electrolyser cell interconnect application in H2/H2O atmosphere

    International Nuclear Information System (INIS)

    Ardigo, M.R.; Popa, I.; Chevalier, S.; Girardon, P.; Perry, F.; Laucournet, R.; Brevet, A.; Desgranges, C.

    2014-01-01

    K41X (AISI 441) stainless steel evidenced a high electrical conductivity after 3000 h ageing in H 2 /H 2 O side when used as interconnect for solid oxide electrolyser cells (SOEC) working at 800 C. Perovskite (La 1-x Sr x MnO 3-δ ) and spinel (Co 3 O 4 ) oxides coatings were applied on the surface of the ferritic steel for ageing at 800 C for 3000 h. Both coatings improved the behaviour of the steel and give interesting opportunities to use the K41X steel as interconnect for hydrogen production via high temperature steam electrolysis. Co 3 O 4 reduced into Co leading to a very good Area Specific Resistance (ASR) parameter, 0.038 Ωcm 2 . Despite a good ASR (0.06 Ωcm 2 ), La 1-x Sr x MnO 3-δ was less promising because it partially decomposed into MnO and La 2 O 3 during ageing in H 2 /H 2 O atmosphere. (authors)

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

    Science.gov (United States)

    Hudson, Reggie L.; Loefler, Mark J.

    2012-01-01

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

  9. Stratospheric H2O

    International Nuclear Information System (INIS)

    Ellsaesser, H.W.

    1979-01-01

    Documentation of the extreme aridity (approx. 3% relative humidity) of the lower stratosphere and the rapid decrease of mixing ratio with height just above the polar tropopause (20-fold in the 1st km) was begun by Dobson et al., (1946) in 1943. They recognized that this extreme and persistent aridity must be dynamically maintained else it would have been wiped out by turbulent diffusion. This led Brewer (1949) to hypothesize a stratospheric circulation in which all air enters through the tropical tropopause where it is freeze dried to a mass mixing ratio of 2 to 3 ppM. This dry air then spreads poleward and descends through the polar tropopauses overpowering upward transport of water vapor by diffusion which would otherwise be permitted by the much warmer temperatures of the polar tropopauses. Questions can indeed be raised as to the absolute magnitudes of stratospheric mixing ratios, the effective temperature of the tropical tropopause cold trap, the reality of winter pole freeze-dry sinks and the representativeness of the available observations suggesting an H 2 O mixing ratio maximum just above the tropical tropopause and a constant mixing ratio from the tropopause to 30 to 35 km. However, no model that better fits all of the available data is available, than does the Brewer (1949) hypothesis coupled with a lower stratosphere winter pole, freeze-dry sink, at least over Antarctica

  10. Broken symmetry phase transition in solid p-H 2, o-D 2 and HD: crystal field effects

    Science.gov (United States)

    Freiman, Yu. A.; Hemley, R. J.; Jezowski, A.; Tretyak, S. M.

    1999-04-01

    We report the effect of the crystal field (CF) on the broken symmetry phase transition (BSP) in solid parahydrogen, orthodeuterium, and hydrogen deuteride. The CF was calculated taking into account a distortion from the ideal HCP structure. We find that, in addition to the molecular field generated by the coupling terms in the intermolecular potential, the Hamiltonian of the system contains a crystal-field term, originating from single-molecular terms in the intermolecular potential. Ignoring the CF is the main cause of the systematic underestimation of the transition pressure, characteristic of published theories of the BSP transition. The distortion of the lattice that gives rise to the negative CF in response to the applied pressure is in accord with the general Le Chatelier-Braun principle.

  11. Phase relations in the system NaCl-KCl-H2O: IV. Differential thermal analysis of the sylvite liquidus in the KCl-H2O binary, the liquidus in the NaCl-KCl-H2O ternary, and the solidus in the NaCl-KCl binary to 2 kb pressure, and a summary of experimental data for thermodynamic-PTX analysis of solid-liquid equilibria at elevated P-T conditions

    Science.gov (United States)

    Chou, I.-Ming; Sterner, S.M.; Pitzer, Kenneth S.

    1992-01-01

    The sylvite liquidus in the binary system KCl-H2O and the liquidus in the ternary system NaCl-KCl-H2O were determined by using isobaric differential thermal analysis (DTA) cooling scans at pressures up to 2 kbars. Sylvite solubilities along the three-phase curve in the binary system KCl-H2O were obtained by the intersection of sylvite-liquidus isopleths with the three-phase curve in a P-T plot. These solubility data can be represented by the equation Wt.% KCl (??0.2) = 12.19 + 0.1557T - 5.4071 ?? 10-5 T2, where 400 ??? T ??? 770??C. These data are consistent with previous experimental observations. The solidus in the binary system NaCl-KCl was determined by using isobaric DTA heating scans at pressures up to 2 kbars. Using these liquidus and solidus data and other published information, a thermodynamic-PTX analysis of solid-liquid equilibria at high pressures and temperatures for the ternary system has been performed and is presented in an accompanying paper (Part V of this series). However, all experimental liquidus, solidus, and solvus data used in this analysis are summarized in this report (Part IV) and they are compared with the calculated values based on the analysis. ?? 1992.

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

    Directory of Open Access Journals (Sweden)

    Zhicai Zhang

    2014-04-01

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

  13. The radiation stability of the RNA base uracil in H2O-ice and CO2-ice: in-situ laboratory measurements with applications to comets, Europa, and Mars

    Science.gov (United States)

    Gerakines, Perry A.; Frail, Sarah; Hudson, Reggie L.

    2017-10-01

    Planetary bodies of astrobiological interest, such as Mars, are often exposed to harsh incident radiation, which will influence the times that molecules can survive on them. Some or all of these bodies may well contain biologically-important organic molecules, some may even have supported life at some point in their history, and some may support life today. Future searches for organic molecules likely will include sampling the martian subsurface or a cometary surface sample return mission, where organics may be frozen in ices dominated by either H2O or CO2, which provide some protection from ionizing radiation.Recently, our research group has published studies of the radiation stability of amino acids, with a focus on glycine - in both undiluted form and in mixtures with H2O and CO2. Here, we present a similar study that focuses on the radiation-chemical kinetics of the RNA base uracil. We compare results for uracil decay for dilution in both H2O and CO2 ices. Moreover, we compare these new results with those for glycine. For each sample, we measured uracil’s destruction rate constant and half-life dose due to irradiation by 0.9-MeV protons. All measurements were made in situ at the temperature of irradiation using IR spectroscopy. Trends with dilution (up to ~300:1) and temperature (up to ~150 K) are considered, and results are discussed in the context of icy planetary surfaces.Acknowledgment: Our work is supported in part by the NASA Emerging Worlds Program and by the NASA Astrobiology Institute through the Goddard Center for Astrobiology.

  14. A new route of oxygen isotope exchange in the solid phase: demonstration in CuSO4.5H2O.

    Science.gov (United States)

    Danon, Albert; Saig, Avraham; Finkelstein, Yacov; Koresh, Jacob E

    2005-11-10

    Temperature-programmed desorption mass spectrometry (TPD-MS) measurements on [(18)O]water-enriched copper sulfate pentahydrate (CuSO(4).5H(2)(18)O) reveal an unambiguous occurrence of efficient oxygen isotope exchange between the water of crystallization and the sulfate in its CuSO(4) solid phase. To the best of our knowledge, the occurrence of such an exchange was never observed in a solid phase. The exchange process was observed during the stepwise dehydration (50-300 degrees C) of the compound. Specifically, the exchange promptly occurs somewhere between 160 and 250 degrees C; however, the exact temperature could not be resolved conclusively. It is shown that only the fifth, sulfate-associated, anionic H(2)O molecule participates in the exchange process and that the exchange seems to occur in a preferable fashion with, at the most, one oxygen atom in SO(4). Such an exchange, occurring below 250 degrees C, questions the common conviction of unfeasible oxygen exchange under geothermic conditions. This new oxygen exchange phenomenon is not exclusive to copper sulfate but is unambiguously observed also in other sulfate- and nitrate-containing minerals.

  15. Degradation of solid oxide cells during co-electrolysis of H2O and CO2: Carbon deposition under high current densities

    DEFF Research Database (Denmark)

    Tao, Youkun; Ebbesen, Sune Dalgaard; Mogensen, Mogens Bjerg

    2012-01-01

    conversions of the reactants were no more than 66.8 %. Ni-YSZ electrode delamination and carbon nano-fibers could be observed after test at the Ni-YSZ | YSZ electrolyte interface for two of the cells. Thermodynamic calculation shows that the reactant conversion needed for carbon formation is above 99 %, far...... above the experimental conversions. The observed carbon formation may be caused by the gas diffusion limitations at high current densities. Carbon nano-fibers were only observed close to the YSZ electrolyte indicating a large overpotential gradient at the TPBs close to the electrolyte......During co-electrolysis of H2O and CO2 using solid oxide cells (SOCs) the risk of carbon deposition in the Ni-YSZ electrode under high current densities (∼ 2.0 A/cm2) was studied in this work. Five galvanostatic tests were performed at current density between 1.5 and 2.25 A/cm2 and the average...

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

    OpenAIRE

    Zhicai Zhang; Jun Jia; Ming Li; Qiaoxia Pang

    2014-01-01

    H2O2 is both bactericidal and the main oxidant responsible for lignin degradation reaction catalyzed by manganese peroxidase (MnP) and lignin peroxidase (LiP). Thus, H2O2 treatment of corn stalk and the implementation of solid-substrate fermentation (SSF) is possible to increase the removal rate of lignin from stalk in the process of SSF and after SSF, while avoiding the need to sterilize the raw materials. To demonstrate this approach, SSF was initially carried out using corn stalk pretreate...

  17. Solid-State Synthesis and Structure of the Enigmatic Ammonium Octaborate: (NH4)2[B7O9(OH)5]·3/4B(OH)3·5/4H2O.

    Science.gov (United States)

    Neiner, Doinita; Sevryugina, Yulia V; Schubert, David M

    2016-09-06

    The compound known since the 19th century as ammonium octaborate was structurally characterized revealing the ammonium salt of the ribbon isomer of the heptaborate anion, [B7O9(OH)5](2-), with boric acid and water molecules. Of composition (NH4)2B7.75O12.63·4.88H2O, it approximates the classical ammonium octaborate composition (NH4)2B8O13·6H2O and has the structural formula {(NH4)2[B7O9(OH)5]}4·3B(OH)3·5H2O. It spontaneously forms at room temperature in solid-state mixtures of ammonium tetraborate and ammonium pentaborate. It crystallizes in the monoclinic space group P21/c with a = 11.4137(2) Å, b = 11.8877(2) Å, c = 23.4459(3) Å, β = 90.092(1)°, V = 3181.19(8) Å(3), and Z = 2 and contains well-ordered ammonium cations and [B7O9(OH)5](2-) anions and disordered B(OH)3 and H2O molecules linked by extensive H bonding. Expeditious solid-state formation of the heptaborate anion under ambient conditions has important implications for development of practical syntheses of industrially useful borates.

  18. Solid-liquid stable phase equilibria of the ternary systems MgCl2 + MgB6O10+ H2O AND MgSO4 + MgB6O10 + H2O at 308.15 K

    Directory of Open Access Journals (Sweden)

    Lingzong Meng

    2014-03-01

    Full Text Available The solubilities and the relevant physicochemical properties of the ternary systems MgCl2 + MgB6O10 + H2O and MgSO4 + MgB6O10 + H2O at 308.15 K were investigated using an isothermal dissolution method. It was found that there is one invariant point, two univariant curves, and two crystallization regions of the systems. The systems belong to a simple co-saturated type, and neither double salts nor solid solutions were found. Based on the extended HW model and its temperature-dependent equations, the single-salt Pitzer parameters β(0, β(1, β(2 and CØ for MgCl2, MgSO4, and Mg(B6O7(OH6, the mixed ion-interaction parameters θCl,B6O10, θSO4,B6O10, ΨMg,Cl,B6O10, ΨMg,SO4,B6O10 of the systems at 308.15 K were fitted, In addition, the average equilibrium constants of the stable equilibrium solids at 308.15 K were obtained by a method using the activity product constant. Then the solubilities of the ternary systems are calculated. The calculated solubilities agree well with the experimental values.

  19. A model-based understanding of solid-oxide electrolysis cells (SOECs) for syngas production by H2O/CO2 co-electrolysis

    Science.gov (United States)

    Menon, Vikram; Fu, Qingxi; Janardhanan, Vinod M.; Deutschmann, Olaf

    2015-01-01

    High temperature co-electrolysis of H2O and CO2 offers a promising route for syngas (H2, CO) production via efficient use of heat and electricity. The performance of a SOEC during co-electrolysis is investigated by focusing on the interactions between transport processes and electrochemical parameters. Electrochemistry at the three-phase boundary is modeled by a modified Butler-Volmer approach that considers H2O electrolysis and CO2 electrolysis, individually, as electrochemically active charge transfer pathways. The model is independent of the geometrical structure. A 42-step elementary heterogeneous reaction mechanism for the thermo-catalytic chemistry in the fuel electrode, the dusty gas model (DGM) to account for multi-component diffusion through porous media, and a plug flow model for flow through the channels are used in the model. Two sets of experimental data are reproduced by the simulations, in order to deduce parameters of the electrochemical model. The influence of micro-structural properties, inlet cathode gas velocity, and temperature are discussed. Reaction flow analysis is performed, at OCV, to study methane production characteristics and kinetics during co-electrolysis. Simulations are carried out for configurations ranging from simple one-dimensional electrochemical button cells to quasi-two-dimensional co-flow planar cells, to demonstrate the effectiveness of the computational tool for performance and design optimization.

  20. La0.8Sr0.2Co0.8Ni0.2O3-δ impregnated oxygen electrode for H2O/CO2 co-electrolysis in solid oxide electrolysis cells

    Science.gov (United States)

    Zheng, Haoyu; Tian, Yunfeng; Zhang, Lingling; Chi, Bo; Pu, Jian; Jian, Li

    2018-04-01

    High-temperature H2O/CO2 co-electrolysis through reversible solid oxide electrolysis cell (SOEC) provides potentially a feasible and eco-friendly way to convert electrical energy into chemicals stored in syngas. In this work, La0.8Sr0.2Co0.8Ni0.2O3-δ (LSCN) impregnated Gd0.1Ce0.9O1.95 (GDC)-(La0.8Sr0.2)0.95MnO3-δ (LSM) composite oxygen electrode is studied as high-performance electrode for H2O/CO2 co-electrolysis. The LSCN impregnated cell exhibits competitive performance with the peak power density of 1057 mW cm-2 at 800 °C in solid oxide fuel cell (SOFC) mode; in co-electrolysis mode, the current density can reach 1.60 A cm-2 at 1.5 V at 800 °C with H2O/CO2 ratio of 2/1. With LSCN nanoparticles dispersed on the surface of GDC-LSM to maximize the reaction active sites, the LSCN impregnated cell shows significant enhanced electrochemical performance at both SOEC and SOFC modes. The influence of feed gas composition (H2O-H2-CO2) and operating voltages on the performance of co-electrolysis are discussed in detail. The cell shows a very stable performance without obvious degradation for more than 100 h. Post-test characterization is analyzed in detail by multiple measurements.

  1. A theoretical study of water equilibria: the cluster distribution versus temperature and pressure for (H2O)n, n = 1-60, and ice.

    Science.gov (United States)

    Lenz, Annika; Ojamäe, Lars

    2009-10-07

    The size distribution of water clusters at equilibrium is studied using quantum-chemical calculations in combination with statistical thermodynamics. The necessary energetic data is obtained by quantum-chemical B3LYP computations and through extrapolations from the B3LYP results for the larger clusters. Clusters with up to 60 molecules are included in the equilibrium computations. Populations of different cluster sizes are calculated using both an ideal gas model with noninteracting clusters and a model where a correction for the interaction energy is included analogous to the van der Waals law. In standard vapor the majority of the water molecules are monomers. For the ideal gas model at 1 atm large clusters [56-mer (0-120 K) and 28-mer (100-260 K)] dominate at low temperatures and separate to smaller clusters [21-22-mer (170-280 K) and 4-6-mer (270-320 K) and to monomers (300-350 K)] when the temperature is increased. At lower pressure the transition from clusters to monomers lies at lower temperatures and fewer cluster sizes are formed. The computed size distribution exhibits enhanced peaks for the clusters consisting of 21 and 28 water molecules; these sizes are for protonated water clusters often referred to as magic numbers. If cluster-cluster interactions are included in the model the transition from clusters to monomers is sharper (i.e., occurs over a smaller temperature interval) than when the ideal-gas model is used. Clusters with 20-22 molecules dominate in the liquid region. When a large icelike cluster is included it will dominate for temperatures up to 325 K for the noninteracting clusters model. Thermodynamic properties (C(p), DeltaH) were calculated with in general good agreement with experimental values for the solid and gas phase. A formula for the number of H-bond topologies in a given cluster structure is derived. For the 20-mer it is shown that the number of topologies contributes to making the population of dodecahedron-shaped cluster larger

  2. Synthetic routes to a nanoscale inorganic cluster [Ga13(μ3-OH)6(μ2-OH)18(H2O)](NO3)15 evaluated by solid-state 71Ga NMR

    International Nuclear Information System (INIS)

    Hammann, Blake A.; Marsh, David A.; Ma, Zayd L.; Wood, Suzannah R.; Eric West, Michael; Johnson, Darren W.; Hayes, Sophia E.

    2016-01-01

    Solid-state 71 Ga NMR was used to characterize a series of [Ga 13 (μ 3 -OH) 6 (μ 2 -OH) 18 (H 2 O)](NO 3 ) 15 “Ga 13 ” molecular clusters synthesized by multiple methods. These molecular clusters are precursors to thin film electronics and may be employed in energy applications. The synthetic routes provide varying levels of impurities in the solid phase, and these impurities often elude traditional characterization techniques such as powder X-ray diffraction and Raman spectroscopy. Solid-state NMR can provide a window into the gallium species even in amorphous phases. This information is vital in order to prevent the impurities from causing defect sites in the corresponding thin films upon gelation and condensation (polymerization) of the Ga 13 clusters. This work demonstrates the resolving power of solid-state NMR to evaluate structure and synthetic quality in the solid state, and the application of high-field NMR to study quadrupolar species, such as 71 Ga. - Graphical abstract: The various synthetic routes and 71 Ga solid-state NMR spectra of the nanoscale inorganic cluster [Ga 13 (μ 3 -OH) 6 (μ 2 -OH) 18 (H 2 O)](NO 3 ) 15 . - Highlights: • Solid-state 71 Ga NMR of hydroxo-aquo metal clusters and the impurities present. • High-field NMR capability allows for quadrupolar species, such as 71 Ga, to be routinely studied. • Efficient and environmentally friendly synthetic routes have been developed to prepare hydroxo-aquo metal clusters.

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

    Science.gov (United States)

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

    2017-04-01

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

  4. Effectiveness and reaction networks of H2O2 vapor with NH3 gas for decontamination of the toxic warfare nerve agent, VX on a solid surface.

    Science.gov (United States)

    Gon Ryu, Sam; Wan Lee, Hae

    2015-01-01

    The nerve agent, O-ethyl S-[2-(diisopropylamino)ethyl] methylphosphonothioate (VX) must be promptly eliminated following its release into the environment because it is extremely toxic, can cause death within a few minutes after exposure, acts through direct skin contact as well as inhalation, and persists in the environment for several weeks after release. A mixture of hydrogen peroxide vapor and ammonia gas was examined as a decontaminant for the removal of VX on solid surfaces at ambient temperature, and the reaction products were analyzed by gas chromatography-mass spectrometry (GC-MS) and nuclear magnetic resonance spectrometry (NMR). All the VX on glass wool filter disks was found to be eliminated after 2 h of exposure to the decontaminant mixtures, and the primary decomposition product was determined to be non-toxic ethyl methylphosphonic acid (EMPA); no toxic S-[2-(diisopropylamino)ethyl] methylphosphonothioic acid (EA-2192), which is usually produced in traditional basic hydrolysis systems, was found to be formed. However, other by-products, such as toxic O-ethyl S-vinyl methylphosphonothioate and (2-diisopropylaminoethyl) vinyl disulfide, were detected up to 150 min of exposure to the decontaminant mixture; these by-products disappeared after 3 h. The two detected vinyl byproducts were identified first in this study with the decontamination system of liquid VX on solid surfaces using a mixture of hydrogen peroxide vapor and ammonia gas. The detailed decontamination reaction networks of VX on solid surfaces produced by the mixture of hydrogen peroxide vapor and ammonia gas were suggested based on the reaction products. These findings suggest that the mixture of hydrogen peroxide vapor and ammonia gas investigated in this study is an efficient decontaminant mixture for the removal of VX on solid surfaces at ambient temperature despite the formation of a toxic by-product in the reaction process.

  5. H2O2: A Dynamic Neuromodulator

    Science.gov (United States)

    Rice, Margaret E.

    2012-01-01

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

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

    International Nuclear Information System (INIS)

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

    2016-01-01

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

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

    Science.gov (United States)

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

    2016-01-01

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

  8. Crystalline and amorphous H2O on Charon

    Science.gov (United States)

    Dalle Ore, Cristina M.; Cruikshank, Dale P.; Grundy, Will M.; Ennico, Kimberly; Olkin, Catherine B.; Stern, S. Alan; Young, Leslie A.; Weaver, Harold A.

    2015-11-01

    Charon, the largest satellite of Pluto, is a gray-colored icy world covered mostly in H2O ice, with spectral evidence for NH3, as previously reported (Cook et al. 2007, Astrophys. J. 663, 1406-1419 Merlin, et al. 2010, Icarus, 210, 930; Cook, et al. 2014, AAS/Division for Planetary Sciences Meeting Abstracts, 46, #401.04). Images from the New Horizons spacecraft reveal a surface with terrains of widely different ages and a moderate degree of localized coloration. The presence of H2O ice in its crystalline form (Brown & Calvin 2000 Science 287, 107-109; Buie & Grundy 2000 Icarus 148, 324-339; Merlin et al, 2010) along with NH3 is consistent with a fresh surface.The phase of H2O ice is a key tracer of variations in temperature and physical conditions on the surface of outer Solar System objects. At Charon’s surface temperature H2O is expected to be amorphous, but ground-based observations (e.g., Merlin et al. 2010) show a clearly crystalline signature. From laboratory experiments it is known that amorphous H2O ice becomes crystalline at temperatures of ~130 K. Other mechanisms that can change the phase of the ice from amorphous to crystalline include micro-meteoritic bombardment (Porter et al. 2010, Icarus, 208, 492) or resurfacing processes such as cryovolcanism.New Horizons observed Charon with the LEISA imaging spectrometer, part of the Ralph instrument (Reuter, D.C., Stern, S.A., Scherrer, J., et al. 2008, Space Science Reviews, 140, 129). Making use of high spatial resolution (better than 10 km/px) and spectral resolving power of 240 in the wavelength range 1.25-2.5 µm, and 560 in the range 2.1-2.25 µm, we report on an analysis of the phase of H2O ice on parts of Charon’s surface with a view to investigate the recent history and evolution of this small but intriguing object.This work was supported by NASA’s New Horizons project.

  9. Hydrothermal synthesis, thermal, structural, spectroscopic and magnetic studies of the Mn5-x Co x (HPO4)2(PO4)2(H2O)4 (x=1.25, 2, 2.5 and 3) finite solid solution

    International Nuclear Information System (INIS)

    Larrea, Edurne S.; Mesa, Jose L.; Pizarro, Jose L.; Arriortua, Maria I.; Rojo, Teofilo

    2007-01-01

    The Mn 5- x Co x (HPO 4 ) 2 (PO 4 ) 2 (H 2 O) 4 (x=1.25, 2, 2.5, 3) finite solid solution has been synthesized by mild hydrothermal conditions under autogeneous pressure. The phases crystallize in the C2/c space group with Z=4, belonging to the monoclinic system. The unit-cell parameters obtained from single crystal X-ray diffraction are: a=17.525(1), b=9.0535(6), c=9.4517(7) A, β=96.633(5) o being R1=0.0436, wR2=0.0454 for Mn75Co25; a=17.444(2), b=9.0093(9), c=9.400(1) A, β=96.76(1) o being R1=0.0381, wR2=0.0490 for Mn60Co40; a=17.433(2), b=8.9989(9), c=9.405(1) A, β=96.662(9) o being R1=0.0438, wR2=0.0515 for Mn50Co50 and a=17.4257(9), b=8.9869(5), c=9.3935(5) A, β=96.685(4) o being R1=0.0296, wR2=0.0460 for Mn40Co60. The structure consists of a three dimensional network formed by octahedral pentameric entities (Mn,Co) 5 O 16 (H 2 O) 6 sharing vertices with the (PO 4 ) 3- and (HPO 4 ) 2- tetrahedra. The limit of thermal stability of these compounds is, approximately, 165 deg. C, near to this mean temperature the phases loose their water content in two successive steps. IR spectra show the characteristic bands of the water molecules and the phosphate and hydrogen-phosphate oxoanions. The diffuse reflectance spectra are consistent with the presence of MO 6 octahedra environments in slightly distorted octahedral geometry, except for the M(3)O 6 octahedron which presents a remarkable distortion and so a higher Dq parameter. The mean value for the Dq and B-Racah parameter for the M(1),(2)O 6 octahedra is 685 and 850 cm -1 , respectively. These parameters for the most distorted M(3)O 6 polyhedron are 825 and 880 cm -1 , respectively. The four phases exhibit antiferromagnetic couplings as the major magnetic interactions. However, a small spin canting phenomenon is observed at low temperatures for the two phases with major content in the anisotropic-Co(II) cation. - Graphical abstract: Crystal structure of the finite solid solution Mn 5-x Co x (HPO 4 ) 2 (PO 4 ) 2 (H

  10. Synthesis and crystal structure of the solid solution Co3(SeO3)3-x(PO3OH)x(H2O) involving crystallographic split positions of Se4+ and P5+.

    Science.gov (United States)

    Zimmermann, Iwan; Johnsson, Mats

    2013-10-21

    Three new cobalt selenite hydroxo-phosphates laying in the solid solution Co3(SeO3)3-x(PO3OH)x(H2O), with x = 0.8, x = 1.0, and x = 1.2 are reported. Single crystals were obtained by hydrothermal synthesis and the crystal structure was determined by single crystal X-ray diffraction. The structure can be described as a 3D framework having selenite and hydroxo-phosphate groups protruding into channels in the crystal structure. Se(4+) and P(5+) share a split position in the structure so that either SeO3 groups having a stereochemically active lone pair or tetrahedrally coordinated PO3OH groups are present. The OH-group is thus only present when the split position is occupied by P(5+). The crystal water is coordinated to a cobalt atom and TG and IR measurements show that the water and hydroxyl groups leave the structure at unusually high temperatures (>450 °C). Magnetic susceptibility measurements show antiferromagnetic coupling below 16 K and a magnetic moment of 4.02(3) μB per Co atom was observed.

  11. EPA H2O Software Tool

    Science.gov (United States)

    EPA H2O allows user to: Understand the significance of EGS in Tampa Bay watershed; visually analyze spatial distribution of the EGS in Tampa Bay watershed; obtain map and summary statistics of EGS values in Tampa Bay watershed; analyze and compare potential impacts of development...

  12. EPA H2O User Manual

    Science.gov (United States)

    EPA H2O is a software tool designed to support research being conducted in the Tampa Bay watershed to provide information, data, and approaches and guidance that communities can use to examine alternatives when making strategic decisions to support a prosperous and environmentall...

  13. X-Ray Diffraction and μ-Raman Investigation of the Monoclinic-Orthorhombic Phase Transition in Th1-xUx(C2O4)2. 2H2O Solid Solutions

    International Nuclear Information System (INIS)

    Clavier, N.; Dacheux, N.; Clavier, N.; Hingant, N.; Dacheux, N.; Barre, N.; Rivenet, M.; Obbade, S.; Abraham, F.

    2010-01-01

    A complete Th 1-x U x (C 2 O 4 ) 2 . 2H 2 O solid solution was prepared by mild hydrothermal synthesis from a mixture of hydrochloric solutions containing cations and oxalic acid. The crystal structure has been solved from twinned single crystals for x=0, 0. 5, and 1 with monoclinic symmetry, space group C2/c, leading to unit cell parameters of a ≅ to 10. 5 Angstroms, b ≅ 8. 5 Angstrom, and c ≅ 9. 6 Angstrom. The crystal structure consists of a two-dimensional arrangement of actinide centers connected through bis-bidentate oxalate ions forming squares. The actinide metal is coordinated by eight oxygen atoms from four oxalate entities and two water oxygen atoms forming a bi-capped square anti-prism. The connection between the layers is assumed by hydrogen bonds between the water molecules and the oxygen of oxalate of an adjacent layer. Under these conditions, the unit cell contains two independent oxalate ions. From high-temperature μ-Raman and X-ray diffraction studies, the compounds were found to undergo a transition to an orthorhombic form (space group Ccca). The major differences in the structural arrangement concern the symmetry of uranium, which decreases from C2 to D2, leading to a unique oxalate group. Consequently, the ν s (C-O) double band observed in the Raman spectra recorded at room temperature turned into a singlet. This transformation was then used to make the phase transition temperature more precise as a function of the uranium content of the sample. (authors)

  14. X-Ray diffraction and mu-Raman investigation of the monoclinic-orthorhombic phase transition in Th(1-x)U(x)(C(2)O(4))(2).2H(2)O solid solutions.

    Science.gov (United States)

    Clavier, Nicolas; Hingant, Nina; Rivenet, Murielle; Obbade, Saïd; Dacheux, Nicolas; Barré, Nicole; Abraham, Francis

    2010-02-15

    A complete Th(1-x)U(x)(C(2)O(4))(2).2H(2)O solid solution was prepared by mild hydrothermal synthesis from a mixture of hydrochloric solutions containing cations and oxalic acid. The crystal structure has been solved from twinned single crystals for x = 0, 0.5, and 1 with monoclinic symmetry, space group C2/c, leading to unit cell parameters of a approximately 10.5 A, b approximately 8.5 A, and c approximately 9.6 A. The crystal structure consists of a two-dimensional arrangement of actinide centers connected through bis-bidentate oxalate ions forming squares. The actinide metal is coordinated by eight oxygen atoms from four oxalate entities and two water oxygen atoms forming a bicapped square antiprism. The connection between the layers is assumed by hydrogen bonds between the water molecules and the oxygen of oxalate of an adjacent layer. Under these conditions, the unit cell contains two independent oxalate ions. From high-temperature mu-Raman and X-ray diffraction studies, the compounds were found to undergo a transition to an orthorhombic form (space group Ccca). The major differences in the structural arrangement concern the symmetry of uranium, which decreases from C2 to D2, leading to a unique oxalate group. Consequently, the nu(s)(C-O) double band observed in the Raman spectra recorded at room temperature turned into a singlet. This transformation was then used to make the phase transition temperature more precise as a function of the uranium content of the sample.

  15. Solid-state synthesis, structure and properties of a novel open-framework cadmium selenite bromide: [Cd10(SeO3)8Br4]·HBr·H2O

    International Nuclear Information System (INIS)

    Chen, Wen-Tong; Wang, Ming-Sheng; Wang, Guan-E; Chen, Hui-Fen; Guo, Guo-Cong

    2013-01-01

    A novel open-framework cadmium selenite bromide, [Cd 10 (SeO 3 ) 8 Br 4 ]·HBr·H 2 O (1), has been obtained by a solid-state reaction at 450 °C, and the structure has been determined by single-crystal X-ray diffraction analysis. Compound 1 crystallizes in Pbcm of the orthorhombic system: a=10.882(3), b=16.275(5), c=18.728(6) Å, V=3317(2) Å 3 , R1/wR2=0.0411/0.0659. Compound 1 is characteristic of a novel 3-D open-framework structure, composing ∞ 2 [CdSeO 3 ] layers and the pillars of edge-shared CdO 3 Br 2 square pyramids. The lattice water molecules and the HBr molecules locate in the voids of the framework. Optical absorption spectrum of 1 reveals the presence of an optical gap of 1.65 eV. Solid-state photoluminescent study indicates that compound 1 exhibits strong violet emission. TG–DSC measurement shows that compound 1 is thermally stable up to 200 °C. - Graphical abstract: A metal selenite halide has been synthesized and features a 3-D open-framework structure, composing edge-shared CdO 8 decahedra and pillars of edge-sharing pentahedra. UV–vis, TG–DSC and luminescent measurements are also reported. Highlights: • This paper reports a novel cadmium selenite bromide obtained by an intermediate-temperature solid-state reaction. • The title compound is characteristic of a novel 3-D open-framework structure, composing ∞ 2 [CdSeO 3 ] layers and the pillars of edge-shared CdO 3 Br 2 square pyramids. • The title compound is thermally stable up to 200 °C. • The title compound has an optical gap of 1.65 eV and exhibits strong violet emission

  16. Adsorption of CO2 and H2O on supported amine sorbents

    NARCIS (Netherlands)

    Veneman, Rens; Zhao, W.; Li, Z.; Cai, N.; Brilman, Derk Willem Frederik

    2014-01-01

    In this work we have evaluated the H2O and CO2 adsorption characteristics of Lewatit VP OC 1065 in view of the potential application of solid sorbents in post combustion CO2 capture. Here we present single component adsorption isotherms for H2O and CO2 as well as co-adsorption experiments. It was

  17. Experimental determination of the H2O + 15 wt% NaCl and H2O + 25 wt% NaCl liquidi to 1.4 GPa

    Science.gov (United States)

    Valenti, P.; Schmidt, C.

    2009-12-01

    The binary H2O+NaCl is one of the most important model systems for chloridic fluids in many geologic environments such as the Earth’s crust, upper mantle, and subducting slabs, and is also applicable to extraterrestrial icy planetary bodies (e.g., Manning 2004, Zolensky et al., 1999). The knowledge on phase equilibria and PVTx properties of this system is still fragmentary at high pressures, e.g., very little has been reported on liquidi at compositions Daniel 2008). In this study, we investigated the liquidus of 15 and 25 wt% NaCl solutions at pressures up to 1.4 GPa. The experiments were performed using a hydrothermal diamond-anvil cell (Bassett et al. 1993) modified for Raman spectroscopy and accurate temperature measurements. A quartz chip, halite, and water were loaded into the sample chamber, which also contained a small trapped air bubble (10 vol%) when it was sealed. The actual salinity was then determined from measurement of the vapor-saturated liquidus temperature. The sample chamber was then compressed until the bubble disappeared. After freezing, phase transitions occurring with increasing temperature were observed optically, and the pressure was determined from the frequency shift of the 464 cm-1 Raman line of quartz (Schmidt and Ziemann 2000). The sample chamber was then compressed further, and the experiment was repeated at various bulk densities until a pressure of ~1.4 GPa was attained. At some conditions, Raman spectra were acquired for identification of the phase assemblage. The solution always crystallized to a single phase upon cooling above ~0.15 GPa at 25 wt% NaCl and above ~1 GPa at 15 wt% NaCl. Raman spectra in the OH stretching region indicate that this phase contains or is a NaCl hydrate other than hydrohalite, probably in solid solution with ice. Melting of this phase produced liquid and hydrohalite and/or ice VI. Ice VI was the last solid that dissolved upon heating, between 1100 MPa, 3 °C and 1370 MPa, 17 °C for 15 wt% NaCl and at

  18. Study of the solubility, viscosity and density in Na+, Zn2+/Cl− − H2O, Na+ − Zn2+ − (H2PO2)− − H2O, Na+, Cl−/(H2PO2)− − H2O, and Zn2+, Cl−/(H2PO2)− − H2O ternary systems, and in Na+, Zn2+/Cl−, (H2PO2)−//H2O reciprocal quaternary system at 273.15 K

    International Nuclear Information System (INIS)

    Adiguzel, Vedat; Erge, Hasan; Alisoglu, Vahit; Necefoglu, Hacali

    2014-01-01

    Highlights: • The physicochemical properties of ternary and one quaternary have been studied. • Reciprocal quaternary systems’ solubility and phase equilibrium have been studied. • In all systems the solid phases have been found. • It was found that Zn(H 2 PO 2 ) 2 salt contains 70% of the general crystallization field. - Abstract: The solubility and the physicochemical properties (density, viscosity) in the Na-Zn- Cl-H 2 O), (Na + Zn + H 2 PO 2 + H 2 O), (Na + Cl + H 2 PO 2 + H 2 O), and (Zn + Cl + H 2 PO 2 + H 2 O) ternaries, and in Na + , Zn 2+ /Cl − , (H 2 PO 2 ) − //H 2 O reciprocal quaternary systems at T = 273.15 K were investigated by using the isothermal method. The diagrams of ternary salts systems, (NaCl + ZnCl 2 + H 2 O), (NaCl + NaH 2 PO 2 + H 2 O), (NaH 2 PO 2 + Zn(H 2 PO 2 ) 2 + H 2 O), (ZnCl 2 + Zn(H 2 PO 2 ) 2 + H 2 O), are plotted in figures 1–4. However, whole ions of reciprocal quaternary salt systems are plotted in figure 5. Additionally, the density and viscosity values of ternary systems vs. their corresponding composition values in weight per cent are plotted in figures 6–10. At the (i) (ZnCl 2 + Zn(H 2 PO 2 ) 2 + H 2 O), (ii) (NaCl + ZnCl 2 + H 2 O), (iii) (NaCl + NaH 2 PO 2 + H 2 O), (iv) (NaH 2 PO 2 + Zn(H 2 PO 2 ) 2 + H 2 O) ternary systems the solid phase compositions have been determined as: (i) Zn(H 2 PO 2 ) 2 ⋅ H 2 O, Zn(H 2 PO 2 ) 2 , ZnCl 2 ⋅ 2H 2 O, (ii) NaCl, 2NaCl ⋅ ZnCl 2 ⋅ 2H 2 O, and ZnCl 2 ⋅ 2H 2 O, (iii) NaCl and NaH 2 PO 2 ⋅ H 2 O, (iv) Zn(H 2 PO 2 ) 2 ⋅ H 2 O and NaH 2 PO 2 ⋅ H 2 O, respectively. On the other hand reciprocal quaternary system was observed as: ZnCl 2 ⋅ 2H 2 O, 2NaCl ⋅ ZnCl 2 ⋅ 2H 2 O, Zn(H 2 PO 2 ) 2 ⋅ H 2 O, NaH 2 PO 2 ⋅ H 2 O, NaCl. According to results, the least soluble salt was Zn(H 2 PO 2 ) 2 . The crystallization field of this salt, being the largest in comparison with those of other salts, occupied 70% of the general crystallization field

  19. Preparation and infrared spectra of the Schiff base solid complexes [UO2(sal-O-phdn)(H2O)] and [UO2(sal-O-phdn) (Et3N)] (sal-O-phdn=n, n'-o-phenylenebissalicylideniminato)

    International Nuclear Information System (INIS)

    Sadeek, S.A.; Teleb, S.M.; Al-Kority, A.M.

    1993-01-01

    In the present communication, we report the preparation of the related two new complexes, [UO 2 (sal-o-phdn)(H 2 O)] and LUO 2 (sal-o-phdn)(Et 3 N)], where sal-o-phdn=N, N'-o-phenylenebis (salicylideneiminato); here U VI is seven-coordinate. The infrared spectra of these two complexes are recorded and assigned. (author). 10 refs., 1 tab

  20. Urchin-Like Ni1/3Co2/3(CO3)1/2(OH)·0.11H2O for Ultrahigh-Rate Electrochemical Supercapacitors: Structural Evolution from Solid to Hollow.

    Science.gov (United States)

    Wei, Wutao; Cui, Shizhong; Ding, Luoyi; Mi, Liwei; Chen, Weihua; Hu, Xianluo

    2017-11-22

    Portable electronics and electric or hybrid electric vehicles are developing in the trend of fast charge and long electric mileage, which ask us to design a novel electrode with sufficient electronic and ionic transport channels at the same time. Herein, we fabricate a uniform hollow-urchin-like Ni 1/3 Co 2/3 (CO 3 ) 1/2 (OH)·0.11H 2 O electrode material through an easy self-generated and resacrificial template method. The one-dimensional chain-like crystal structure unit containing the metallic bonding and the intercalated OH - and H 2 O endow this electrode material with abundant electronic and ionic transport channels. The hollow-urchin-like structure built by nanorods contributes to the large electrode-electrolyte contact area ensuring the supply of ions at high current. CNTs are employed to transport electrons between electrode material and current collector. The as-assembled NC-CNT-2//AC supercapacitor device exhibits a high specific capacitance of 108.3 F g -1 at 20 A g -1 , a capacitance retention ratio of 96.2% from 0.2 to 20 A g -1 , and long cycle life. Comprehensive investigations unambiguously highlight that the unique hollow-urchin-like Ni 1/3 Co 2/3 (CO 3 ) 1/2 (OH)·0.11H 2 O electrode material would be the right candidate for advanced next-generation supercapacitors.

  1. DFT Calculation of IR Absorption Spectra for PCE-nH2O, TCE-nH2O, DCE-nH2O, VC-nH2O for Small and Water-Dominated Molecular Clusters

    Science.gov (United States)

    2017-10-31

    VC-nH2O for Small and Water-Dominated Molecular Clusters October 31, 2017 Approved for public release; distribution is unlimited. L. Huang S.g...Calculation of IR Absorption Spectra for PCE-nH2O, TCE-nH2O, DCE-nH2O, VC-nH2O for Small and Water-Dominated Molecular Clusters L. Huang,1 S.G...nH2O molecular clusters using density function theory (DFT). DFT can provide interpretation of absorption spectra with respect to molecular

  2. Optical spectrophotometry of Comet P/Giacobini-Zinner and emission profiles of H2O+

    Science.gov (United States)

    Strauss, M. A.; Mccarthy, P. J.; Spinrad, H.

    1986-01-01

    Two-dimensional CCD spectrograms were obtained of Comet P/Giacobini-Zinner (1984e) on five occasions between July and October 1985. Spatial emission profiles of H2O+ were extracted at 6198 angstroms (the strongest ionic line in the visible spectrum). This emission line traces the extent of the ion, or plasma, tail. The spectrographic slit was placed approximately along the trajectory of the ICE spacecraft on September 11, 1985; the resulting H2O+ profile has a full-width-half-maximum of about 5700 km, about three times that of the plasma density profile measured by ICE, and has a full-width-zero-intensity of about 30,000 km, very similar to the ICE values. H2O production rates for the comet are derived and compared with those of Comet P/Halley (1982i).

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

    Science.gov (United States)

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

    2017-10-01

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

  4. Heterogeneous kinetics of H2O, HNO3 and HCl on HNO3 hydrates (α-NAT, β-NAT, NAD) in the range 175-200 K

    Science.gov (United States)

    Iannarelli, Riccardo; Rossi, Michel J.

    2016-09-01

    Experiments on the title compounds have been performed using a multidiagnostic stirred-flow reactor (SFR) in which the gas phase as well as the condensed phase has been simultaneously investigated under stratospheric temperatures in the range 175-200 K. Wall interactions of the title compounds have been taken into account using Langmuir adsorption isotherms in order to close the mass balance between deposited and desorbed (recovered) compounds. Thin solid films at 1 µm typical thickness have been used as a proxy for atmospheric ice particles and have been deposited on a Si window of the cryostat, with the optical element being the only cold point in the deposition chamber. Fourier transform infrared (FTIR) absorption spectroscopy in transmission as well as partial and total pressure measurement using residual gas mass spectrometry (MS) and sensitive pressure gauges have been employed in order to monitor growth and evaporation processes as a function of temperature using both pulsed and continuous gas admission and monitoring under SFR conditions. Thin solid H2O ice films were used as the starting point throughout, with the initial spontaneous formation of α-NAT (nitric acid trihydrate) followed by the gradual transformation of α- to β-NAT at T > 185 K. Nitric acid dihydrate (NAD) was spontaneously formed at somewhat larger partial pressures of HNO3 deposited on pure H2O ice. In contrast to published reports, the formation of α-NAT proceeded without prior formation of an amorphous HNO3 / H2O layer and always resulted in β-NAT. For α- and β-NAT, the temperature-dependent accommodation coefficient α(H2O) and α(HNO3), the evaporation flux Jev(H2O) and Jev(HNO3) and the resulting saturation vapor pressure Peq(H2O) and Peq(HNO3) were measured and compared to binary phase diagrams of HNO3 / H2O in order to afford a thermochemical check of the kinetic parameters. The resulting kinetic and thermodynamic parameters of activation energies for evaporation (Eev) and

  5. H2O2 space shuttle APU

    Science.gov (United States)

    1975-01-01

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

  6. Solid-state thermal decomposition of the [Co(NH3)5CO3]NO3·0.5H2O complex: A simple, rapid and low-temperature synthetic route to Co3O4 nanoparticles

    International Nuclear Information System (INIS)

    Farhadi, Saeid; Safabakhsh, Jalil

    2012-01-01

    Highlights: ► [Co(NH 3 ) 5 CO 3 ]NO 3 ·0.5H 2 O complex was used for preparing pure Co 3 O 4 nanoparticles. ► Co 3 O 4 nanoparticles were prepared at low temperature of 175 °C. ► Co 3 O 4 nanoparticles show a weak ferromagnetic behaviour at room temperature. ► The method is simple, low-cost and suitable for the production of Co 3 O 4 . - Abstract: Co 3 O 4 nanoparticles were easily prepared via the decomposition of the pentammine(carbonato)cobalt(III) nitrate precursor complex [Co(NH 3 ) 5 CO 3 ]NO 3 ·0.5H 2 O at low temperature (175 °C). The product was characterized by thermal analysis, X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FT-IR), UV–visible spectroscopy, transmission electron microscopy (TEM), energy-dispersive X-ray spectroscopy (EDX), Raman spectroscopy, Brunauer–Emmett–Teller (BET) specific surface area measurements and magnetic measurements. The FT-IR, XRD, Raman and EDX results indicated that the synthesized Co 3 O 4 nanoparticles are highly pure and have a single phase. The TEM analysis revealed nearly uniform and quasi-spherical Co 3 O 4 nanoparticles with an average particle size of approximately 10 nm. The optical absorption spectrum of the Co 3 O 4 nanoparticles showed two direct band gaps of 2.18 and 3.52 eV with a red shift in comparison with previous reported values. The prepared Co 3 O 4 nanoparticles showed a weak ferromagnetic behaviour that could be attributed to uncompensated surface spins and/or finite-size effects. Using the present method, Co 3 O 4 nanoparticles can be produced without expensive organic solvents and complicated equipment. This simple, rapid, safe and low-cost synthetic route can be extended to the synthesis of other transition-metal oxides.

  7. Thermodynamic model for solution behavior and solid-liquid equilibrium in Na-Al(III)-Fe(III)-Cr(III)-Cl-H2O system at 25°C

    Science.gov (United States)

    André, Laurent; Christov, Christomir; Lassin, Arnault; Azaroual, Mohamed

    2018-03-01

    The knowledge of the thermodynamic behavior of multicomponent aqueous electrolyte systems is of main interest in geo-, and environmental-sciences. The main objective of this study is the development of a high accuracy thermodynamic model for solution behavior, and highly soluble M(III)Cl3(s) (M= Al, Fe, Cr) minerals solubility in Na-Al(III)-Cr(III)-Fe(III)-Cl-H2O system at 25°C. Comprehensive thermodynamic models that accurately predict aluminium, chromium and iron aqueous chemistry and M(III) mineral solubilities as a function of pH, solution composition and concentration are critical for understanding many important geochemical and environmental processes involving these metals (e.g., mineral dissolution/alteration, rock formation, changes in rock permeability and fluid flow, soil formation, mass transport, toxic M(III) remediation). Such a model would also have many industrial applications (e.g., aluminium, chromium and iron production, and their corrosion, solve scaling problems in geothermal energy and oil production). Comparisons of solubility and activity calculations with the experimental data in binary and ternary systems indicate that model predictions are within the uncertainty of the data. Limitations of the model due to data insufficiencies are discussed. The solubility modeling approach, implemented to the Pitzer specific interaction equations is employed. The resulting parameterization was developed for the geochemical Pitzer formalism based PHREEQC database.

  8. Study of defects in solids. I. Chemical effects related to the (n,γ) reaction and electron capture. II. dehydration of Ba(ClO3)2,H2O

    International Nuclear Information System (INIS)

    Mathieu, J.-P.

    1975-01-01

    The first part of this work concerns the Moessbauer effect study of two groups of phenomena: those related to the (n,γ) reaction and those connected with radioactive disintegration of 57 Co by electron capture. Hf compounds were chosen for the first group, and a chemical study was also devoted to the effects of the (n,γ) reaction in organic complexes of Cr(III). Nuclear recoil and thermal annealing of these compounds were investigated. For the second group an attempt was made to show the effects of the environment on the chemical state of the 57 Fe detected. In part two the Ba(ClO 3 ) 2 ,H 2 O dehydratation mechanism was examined by quadrupolar nuclear resonance. By this technique, combined with X-ray diffraction and Raman spectroscopy, the effects of dehydration on the characteristics of the quadrupolar interaction and on the crystal structure of the compound were demonstrated. A model of the dehydration process is proposed [fr

  9. Thermodynamic model for solution behavior and solid-liquid equilibrium in Na-Al(III-Fe(III-Cr(III-Cl-H2O system at 25°C

    Directory of Open Access Journals (Sweden)

    André Laurent

    2018-03-01

    Full Text Available The knowledge of the thermodynamic behavior of multicomponent aqueous electrolyte systems is of main interest in geo-, and environmental-sciences. The main objective of this study is the development of a high accuracy thermodynamic model for solution behavior, and highly soluble M(IIICl3(s (M= Al, Fe, Cr minerals solubility in Na-Al(III-Cr(III-Fe(III-Cl-H2O system at 25°C. Comprehensive thermodynamic models that accurately predict aluminium, chromium and iron aqueous chemistry and M(III mineral solubilities as a function of pH, solution composition and concentration are critical for understanding many important geochemical and environmental processes involving these metals (e.g., mineral dissolution/alteration, rock formation, changes in rock permeability and fluid flow, soil formation, mass transport, toxic M(III remediation. Such a model would also have many industrial applications (e.g., aluminium, chromium and iron production, and their corrosion, solve scaling problems in geothermal energy and oil production. Comparisons of solubility and activity calculations with the experimental data in binary and ternary systems indicate that model predictions are within the uncertainty of the data. Limitations of the model due to data insufficiencies are discussed. The solubility modeling approach, implemented to the Pitzer specific interaction equations is employed. The resulting parameterization was developed for the geochemical Pitzer formalism based PHREEQC database.

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

    Science.gov (United States)

    Sakugawa, H.; Kaplan, I. R.

    1987-01-01

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

  11. Untersuchungen am System NMMO/H2O/Cellulose

    OpenAIRE

    Cibik, T.

    2003-01-01

    Die vorliegende Arbeit befasst sich mit der Untersuchung des Zweistoffsystems N-Methylmorpholin-N-oxid (NMMO)/H2O und des Dreistoffsystems NMMO/H2O/Cellulose sowie mit der Herstellung und Charakterisierung von faserverstärkten Cellulosefolien. Das binäre System wird mittels Dynamischer Differenzkalorimetrie und Röntgenweitwinkel-Diffraktometrie untersucht und dadurch das Schmelzverhalten und die Phasenzusammensetzung dieses Systems im festen Zustand als Funktion des NMMO/H2O-Verhältnisses bes...

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

    Science.gov (United States)

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

    2014-01-01

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

  13. Reactions of 11C recoil atoms in the systems H2O-NH3, H2O-CH4 and NH3-CH4

    International Nuclear Information System (INIS)

    Nebeling, B.

    1988-11-01

    In this study the chemical reactions of recoil carbon 11 in the binary gas mixtures H 2 O-NH 3 , H 2 O-CH 4 and NH 3 -CH 4 in different mixing ratios as well as in solid H 2 O and in a solid H 2 O-NH 3 mixture were analyzed in dependence of the dose. The analyses were to serve e.g. the simulation of chemical processes caused by solar wind, solar radiation and cosmic radiation in the coma and core of comets. They were to give further information about the role of the most important biogeneous element carbon, i.e. carbon, in the chemical evolution of the solar system. Besides the actual high energy processes resulting in the so-called primary products, also the radiation-chemical changes of the primary products were also observed in a wide range of dosing. The generation of the energetic 11 C atoms took place according to the target composition by the nuclear reactions 14 N(p,α) 11 C, 12 C( 3 He,α) 11 C or the 16 O(p,αpn) 11 C reaction. The identification of the products marked with 11 C was carried out by means of radio gas chromatography or radio liquid chromatography (HPLC). (orig./RB) [de

  14. H2O Formation in C-rich AGB Winds

    NARCIS (Netherlands)

    Lombaert, R.; Decin, L.; Royer, P.; de Koter, A.; Cox, N.L.J.; De Ridder, J.; Khouri, T.; Agúndez, M.; Blommaert, J.A.D.L.; Gernicharo, J.; González-Alfonso, E.; Groenewegen, M.A.T.; Kerschbaum, F.; Neufeld, D.; Vandenbussche, B.; Waelkens, C.

    2015-01-01

    The Herschel detection of warm H2O vapor emission from C-rich winds of AGB stars challenges the current understanding of circumstellar chemistry. Two mechanisms have been invoked to explain warm H2O formation. In the first, penetration of UV interstellar radiation through a clumpy circumstellar

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

    Directory of Open Access Journals (Sweden)

    Afsane Chavoshani

    2016-07-01

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

  16. Structure of Chloro bis(1,10-phenanthroline)Cobalt(II) Complex, [Co(phen)2(Cl)(H2O)]Cl · 2H2O

    International Nuclear Information System (INIS)

    Zhao, Pu Su; Lu, Lu De; Jian, Fang Fang

    2003-01-01

    The crystal structure of [Co(phen) 2 (Cl)(H 2 O)] Cl · 2H 2 O(phen=1,10-phenanthroline) has been determined by X-ray crystallography. It crystallizes in the triclinic system, space group P 1 , with lattice parameters a=9.662(2), b=11.445(1), c=13.037(2)A, α=64.02(1), β=86.364(9), γ=78.58(2) .deg., and Z=2. The coordinated cations contain a six-coordinated cobalt atom chelated by two phen ligands and one chloride anion and one water ligand in cis arrangement. In addition to the chloride coordinated to the cobalt, there are one chloride ion and four water molecules which complete the crystal structure. In the solid state, the title compound forms three dimensional network structure through hydrogen bonds, within which exists the strongest hydrogen bond (O(3)-O(4)=2.33A). The intermolecular hydrogen bonds connect the [Co(phen) 2 (Cl)(H 2 O)] 1+ , H 2 O moieties and chloride ion

  17. H2O grain size and the amount of dust in Mars' residual North polar cap

    Science.gov (United States)

    Kieffer, H.H.

    1990-01-01

    In Mars' north polar cap the probable composition of material residual from the annual condensation cycle is a mixture of fine dust and H2O grains of comparable size and abundance. However, metamorphism of such material will gradually lower its albedo by increasing the size of the H2O grains only. If the cap is undergoing net annual sublimation (as inferred from water vapor observations), late summer observations should be of old ice with H2O grain sizes of 100 ??m or more. Ice of this granularity containing 30% fine dust has a reflectivity similar to that of dust alone; the observed albedo and computed ice grain size imply dust concentrations of 1 part per 1000 or less. The brightness of the icy areas conflicts with what would be expected for a residual cap deposited by an annual cycle similar to that observed by Viking and aged for thousands of years. The residual cap surface cannot be "old dirty' ice. It could be old, coarse, and clean; or it could be young, fine, and dirty. This brings into question both the source of the late summer water vapor and the formation rate of laminated terrain. -Author

  18. Photoionization of H2O at high resolution

    International Nuclear Information System (INIS)

    Dehmer, P.M.; Chupka, W.A.

    1978-01-01

    The relative photoionization cross sections for the formation of H 2 O + , OH + , and H + from H 2 O were measured at high wavelength resolution using a 3-meter photoionization mass spectrometer equipped with a quadrupole mass flter and a 1-meter photoionization mass spectrometer equipped with a 12-inch radius, 60 0 sector magnetic mass spectrometer. Discrete structure in the parent ion photoionization efficiency curve is interpreted in terms of Rydberg series converging to excited states of the H 2 O + ion. 9 references

  19. Amorphous ice. A microporous solid: astrophysical implications

    International Nuclear Information System (INIS)

    Mayer, E.; Pletzer, R.

    1987-01-01

    Vapour deposited amorphous ice, investigated by N 2 -adsorption at 77 K, was found to be a microporous solid. Micropore volumes between 0.21 and 0.12 cm 3 /g were determined by comparison plots and Dubinin-Radushkevich plots. Warming of the adsorbent to 113 K caused sintering and reduction of apparent surface area by about an order of magnitude; in the presence of adsorbed gas, large amounts of gas were enclosed in the solid. The influence of micropores on the H 2 recombination rate on amorphous ice in interstellar dust and on adsorption of volatile gases in comets is discussed briefly

  20. Thermodynamics of the CSCl-H2O system at low temperatures

    International Nuclear Information System (INIS)

    Monnin, C.; Dubois, M.

    1999-01-01

    The interpretation of fluid-inclusion data requires knowledge of phase diagrams at low (subfreezing) temperatures. From the example of the CsCl-H 2 O system, we here investigate the possibility to build such diagrams from thermodynamic models of aqueous solutions parameterized at higher temperatures. Holmes and Mesmer (1983) have built a model for the thermodynamic properties of CsCl(aq) based on Pitzer's equation fit to thermodynamic data mainly at temperatures above 0 C along with a few freezing-point-depression data down to -8 C. We show how this model can be used along with the published water-ice equilibrium constant and thermodynamic data at 25 C for Cs + (aq), Cl - (aq) and CsCl(s), to predict with confidence the ice-liquid-vapor (ILV) and the salt-liquid-vapor (SLV) curves down to the eutectic temperature for the CsCl-H 2 O system. (orig.)

  1. H2O masers in star-forming regions

    International Nuclear Information System (INIS)

    Downes, D.

    1985-01-01

    Water vapour near star forming regions was first detected by Cheung et al. (1969) and shortly thereafter was recognised to be maser emission. In spite of this 15 year history of H 2 O observations, the problem of interpreting such strong H 2 O masers as W49 and Orion is still very acute. Not one of the models now available can explain in an unconstrained fashion why a very large maser flux can emanate from clouds of such small size. Whereas some models proposed to explain OH masers have retained their plausibility under the pressure of new observations, H 2 O models have not. The author outlines the background of the H 2 O problem, stating that the strongest of the masers discovered are still not satisfactorily explained today. (Auth.)

  2. Phase formation in the systems ZrO2-H2SO4-Na2SO4 (NaCl)-H2O

    International Nuclear Information System (INIS)

    Sozinova, Yu.P.; Motov, D.L.; Rys'kina, M.P.

    1988-01-01

    Formation of solid phases in the systems ZrO 2 - H 2 SO 4 - Na 2 SO 4 (NaCl) - H 2 O at 25 and 75 deg C is studied. Three basic Na 2 Zr(OH) 2 (SO 4 ) 2 x (0.2 - 0.4)H 2 O, NaZrOH(SO 4 ) 2 x H 2 O, NaZrO 0.5 (OH) 2 SO 4 x 2H 2 O and three normal sodium sulfatozirconates Na 2 Zr(SO 4 ) 3 x 3H 2 O, Na 4 Zr(SO 4 ) 4 x 3H 2 O, Na 6 Zr(SO 4 ) 5 x 4H 2 O have been isolated, their solubility and crystal optical properties are determined

  3. H2O sources in regions of star formation

    International Nuclear Information System (INIS)

    Lo, K.Y.; Burke, B.F.; Haschick, A.D.

    1975-01-01

    Regions and objects believed to be in early stages of stellar formation have been searched for H 2 O 22-GHz line emission with the Haystack 120-foot (37 m) telescope. The objects include radio condensations, infrared objects in H ii regions, and Herbig-Haro objects. Nine new H 2 O sources were detected in the vicinity of such objects, including the Sharpless H ii regions S152, S235, S255, S269, G45.1+0.1, G45.5+0.1, AFCRL infrared object No. 809--2992, and Herbig-Haro objects 1 and 9. The new H 2 O sources detected in H ii regions are associated, but not coincident, with the the radio condensations. Water vapor line emission was detected in approx.25 percent of the regions searched. The association of H 2 O sources with regions of star formation is taken to be real. The spatial relationship of H 2 O sources to infrared objects, radio condensations, class I OH sources, and molecular clouds are discussed. The suggestion is made that an H 2 O source may be excited by a highly obscured star of extreme youth

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

    Science.gov (United States)

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

    2004-01-01

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

  5. Heterogeneous kinetics of H2O, HNO3 and HCl on HNO3 hydrates (α-NAT, β-NAT, NAD in the range 175–200 K

    Directory of Open Access Journals (Sweden)

    R. Iannarelli

    2016-09-01

    Full Text Available Experiments on the title compounds have been performed using a multidiagnostic stirred-flow reactor (SFR in which the gas phase as well as the condensed phase has been simultaneously investigated under stratospheric temperatures in the range 175–200 K. Wall interactions of the title compounds have been taken into account using Langmuir adsorption isotherms in order to close the mass balance between deposited and desorbed (recovered compounds. Thin solid films at 1 µm typical thickness have been used as a proxy for atmospheric ice particles and have been deposited on a Si window of the cryostat, with the optical element being the only cold point in the deposition chamber. Fourier transform infrared (FTIR absorption spectroscopy in transmission as well as partial and total pressure measurement using residual gas mass spectrometry (MS and sensitive pressure gauges have been employed in order to monitor growth and evaporation processes as a function of temperature using both pulsed and continuous gas admission and monitoring under SFR conditions. Thin solid H2O ice films were used as the starting point throughout, with the initial spontaneous formation of α-NAT (nitric acid trihydrate followed by the gradual transformation of α- to β-NAT at T > 185 K. Nitric acid dihydrate (NAD was spontaneously formed at somewhat larger partial pressures of HNO3 deposited on pure H2O ice. In contrast to published reports, the formation of α-NAT proceeded without prior formation of an amorphous HNO3 ∕ H2O layer and always resulted in β-NAT. For α- and β-NAT, the temperature-dependent accommodation coefficient α(H2O and α(HNO3, the evaporation flux Jev(H2O and Jev(HNO3 and the resulting saturation vapor pressure Peq(H2O and Peq(HNO3 were measured and compared to binary phase diagrams of HNO3 ∕ H2O in order to afford a thermochemical check of the kinetic parameters. The resulting kinetic and thermodynamic parameters of activation

  6. Crystal structure of strontium osmate (8) Sr[OsO5(H2O)]x3H2O

    International Nuclear Information System (INIS)

    Nevskij, N.N; Ivanov-Ehmin, B.N.; Nevskaya, N.A.; Belov, N.V.; AN SSSR, Moscow. Inst. Kristallografii)

    1982-01-01

    Crystal structure of the Sr[OsO 5 (H 2 O)]x3H 2 O complex is studied. Rhombic P-cell has the parameters: a=6.426(1), b=7.888(1), c=14.377(5) A, Vsub(c)=729 A 3 . The R-factor equals 0.034. The coordinates of the basis atoms and isotropic temperature corrections, as well as basic interatomic distances, are determined

  7. The system HoCl3-YCl3-H2O (25 deg C)

    International Nuclear Information System (INIS)

    Sorokina, A.A.; Yudina, N.G.

    1981-01-01

    By solubility method the system HoCl 3 -YCl 3 -H 2 O at 25 deg C has been studied. It is shown that in this system the continuous serie of solid solutions is formed. The liquid solutions of this system have been investigated by the isopiestic method. The values of activity coefficients, activity, free energy formation and excess free energy of solid solutions are calculated [ru

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

    Science.gov (United States)

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

    2016-06-09

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

  9. Electrochemical, H2O2-Boosted Catalytic Oxidation System

    Science.gov (United States)

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

    2004-01-01

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

  10. High Pressure and High Temperature State of Oxygen Enriched Ice

    Science.gov (United States)

    LI, M.; Zhang, S.; Jeanloz, R.; Militzer, B.

    2016-12-01

    Interior models for Uranus and Neptune include a hydrogen/helium/water outer envelope and a core of rock and metal at the center, with superionic water-rich ice proposed as comprising an intermediate layer. Here we consider an oxygen-enriched ice, such as H2O2 hydrogen peroxide (± water), that could form through chemical reaction between water-rich and underlying rocky (i.e., oxygen-rich) layers. As oxygen and its compounds (e.g., H2O, SiO2) form metallic fluids at pressures above 100-150 GPa, the problem amounts to considering oxygen alloying of semiconducting or metallic water. The density of H2O2 is 1.45 g/cc at ambient pressure and 0° C, increasing to 1.71 g/cc in the solid state at about -20° C. There are no Hugoniot data beyond 30 GPa, so we estimated Hugoniots for H2O2 with different initial densities, using both a mixing model based on Hugoniot data for H2O2 and 1/2 O2 (molar volume summation under pressure) and ab initio calculations for unreacted H2O2. The results agree with each other to pressures of about 200 GPa, and the ab initio calculations show evidence of a superionic state at temperatures as low as 500 K, much lower than for water ice. Hydrogen peroxide is expected to be liquid along planetary isentropes for Uranus and Neptune, suggesting that H2O2 may not be present as a pure compound in these planets. Instead, oxygen-enriched H2O ice may be the relevant form of water and oxygen, and might be produced in the laboratory by way of dynamic compression of H2O2 or laser-heating of statically compressed H2O + O2 and/or H2O2.

  11. Normalized fluctuations, H2O vs n-hexane: Site-correlated percolation

    Science.gov (United States)

    Koga, Yoshikata; Westh, Peter; Sawamura, Seiji; Taniguchi, Yoshihiro

    1996-08-01

    Entropy, volume and the cross fluctuations were normalized to the average volume of a coarse grain with a fixed number of molecules, within which the local and instantaneous value of interest is evaluated. Comparisons were made between liquid H2O and n-hexane in the range from -10 °C to 120 °C and from 0.1 MPa to 500 MPa. The difference between H2O and n-hexane in temperature and pressure dependencies of these normalized fluctuations was explained in terms of the site-correlated percolation theory for H2O. In particular, the temperature increase was confirmed to reduce the hydrogen bond probability, while the pressure appeared to have little effect on the hydrogen bond probability. According to the Le Chatelier principle, however, the putative formation of ``ice-like'' patches at low temperatures due to the site-correlated percolation requirement is retarded by pressure increases. Thus, only in the limited region of low pressure (<300 MPa) and temperature (<60 °C), the fluctuating ice-like patches are considered to persist.

  12. Ultrafast Librational Relaxation of H2O in Liquid Water

    DEFF Research Database (Denmark)

    Petersen, Jakob; Møller, Klaus Braagaard; Rey, Rossend

    2013-01-01

    The ultrafast librational (hindered rotational) relaxation of a rotationally excited H2O molecule in pure liquid water is investigated by means of classical nonequilibrium molecular dynamics simulations and a power and work analysis. This analysis allows the mechanism of the energy transfer from...... the excited H2O to its water neighbors, which occurs on a sub-100 fs time scale, to be followed in molecular detail, i.e., to determine which water molecules receive the energy and in which degrees of freedom. It is found that the dominant energy flow is to the four hydrogen-bonded water partners in the first...

  13. Phase diagrams and physicochemical properties of Li+,K+(Rb+)//borate-H2O systems at 323 K

    Science.gov (United States)

    Feng, Shan; Yu, Xudong; Cheng, Xinglong; Zeng, Ying

    2017-11-01

    The phase and physicochemical properties diagrams of Li+,K+(Rb+)//borate-H2O systems at 323 K were constructed using the experimentally measured solubilities, densities, and refractive indices. The Schreinemakers' wet residue method and the X-ray diffraction were used for the determination of the compositions of solid phase. Results show that these two systems belong to the hydrate I type, with no solid solution or double salt formation. The borate phases formed in our experiments are RbB5O6(OH)4 · 2H2O, Li2B4O5(OH)4 · H2O, and K2B4O5(OH)4 · 2H2O. Comparison between the stable phase diagrams of the studied system at 288, 323, and 348 K show that in this temperature range, the crystallization form of salts do not changed. With the increase in temperature, the crystallization field of Li2B4O5(OH)4 · H2O salt at 348 K is obviously larger than that at 288 K. In the Li+,K+(Rb+)//borate-H2O systems, the densities and refractive indices of the solutions (at equilibrium) increase along with the mass fraction of K2B4O7 (Rb2B4O7), and reach the maximum values at invariant point E.

  14. Reaction of ferric leghemoglobin with H2O2

    DEFF Research Database (Denmark)

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

    1995-01-01

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

  15. Surface tension of H2O and D2O

    International Nuclear Information System (INIS)

    Vargaftik, N.B.; Voljak, L.D.; Volkov, B.N.

    1975-01-01

    There is a great number of works on surface tension of clean water (H 2 O) at temperatures up to 100 deg C and very few above the boiling point. Works on surface tension of heavy water (D 2 O) are insufficient. A review of works on surface tension of both kinds of water is given

  16. Low-Temperature Thermal Reactions Between SO2 and H2O2 and Their Relevance to the Jovian Icy Satellites

    Science.gov (United States)

    Loeffler, Mark J.; Hudson, Reggie L.

    2013-01-01

    Here we present first results on a non-radiolytic, thermally-driven reaction sequence in solid H2O +SO2 + H2O2 mixtures at 50-130 K, which produces sulfate (SO(-2)/(4)), and has an activation energy of 53 kJ/mole. We suspect that these results may explain some of the observations related to the presence and distribution of H2O2 across Europa's surface as well as the lack of H2O2 on Ganymede and Callisto.

  17. Improved radiosensitive microcapsules using H2O2

    International Nuclear Information System (INIS)

    Harada, Satoshi; Ehara, Shigeru; Ishii, Keizo

    2010-01-01

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

  18. Tricyclic sesquiterpene copaene prevents H2O2-induced neurotoxicity

    Directory of Open Access Journals (Sweden)

    Hasan Turkez

    2014-02-01

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

  19. Observations of interstellar H2O emission at 183 Gigahertz

    International Nuclear Information System (INIS)

    Waters, J.W.; Gustincic, J.J.; Kakar, R.K.; Kuiper, T.B.H.; Roscoe, H.K.; Swanson, P.N.; Rodriguez Kuiper, E.N.; Kerr, A.R.; Thaddeus, P.

    1980-01-01

    Line emission at 183 GHz by the 3 13 --2 20 rotational transition of water vapor has been detected from the Orion Nebula with the NASA Kuiper Airborne Observatory 91 cm telescope. The peak antenna temperature of the line is 15 K, its LSR velocity is 8 km s -1 , and its width is 15 km s -1 . The velocity profile has characteristics similar to those for CO:a narrow (approx.4 km s -1 ) ''spike'' centered at 9.5 km s -1 and a broad ''plateau'' with flaring wings centered at approx.8 km s -1 . Our 7'.5 antenna beam did not resolve the source. The 183 GHz H 2 O plateau emission appears enhanced above that expected for thermal excitation if it originates from the no greater than 1' region characteristic of plateau emission from all other observed molecules. The spike emission is consistent with an optically thick source of the approximated size of the well-known molecular ridge in Orion having the H 2 O in thermal equilibrium at Tapprox. =50 K. If this is the case, then the H 2 O column density giving rise to the spike is N/sub H/2/sub O/> or =3 x 10 17 cm -2 . An excitation calculation implies N/sub H/2/sub O/approx. =10 18 cm -2 for a source the size of the molecular ridge. These results imply that H 2 O is one of the more abundant species in the Orion Molecualr Cloud.H 2 O emission at 183 GHz was not detected in Sgr A, Sgr B2, W3, W43, W49, W51, DR 21, NGC 1333, NGC 7027, GL 2591, or the rho Oph cloud; it may have been detected in M17

  20. Co3(PO42·4H2O

    Directory of Open Access Journals (Sweden)

    Yang Kim

    2008-10-01

    Full Text Available Single crystals of Co3(PO42·4H2O, tricobalt(II bis[orthophosphate(V] tetrahydrate, were obtained under hydrothermal conditions. The title compound is isotypic with its zinc analogue Zn3(PO42·4H2O (mineral name hopeite and contains two independent Co2+ cations. One Co2+ cation exhibits a slightly distorted tetrahedral coordination, while the second, located on a mirror plane, has a distorted octahedral coordination environment. The tetrahedrally coordinated Co2+ is bonded to four O atoms of four PO43− anions, whereas the six-coordinate Co2+ is cis-bonded to two phosphate groups and to four O atoms of four water molecules (two of which are located on mirror planes, forming a framework structure. In addition, hydrogen bonds of the type O—H...O are present throughout the crystal structure.

  1. Pb-H2O Thermogravimetric Plants. The Rankine Cycle

    International Nuclear Information System (INIS)

    Arosio, S.; Carlevaro, R.

    2000-01-01

    An economic evaluation concerning Pb-H 2 O thermogravimetric systems with an electric power in the range 200-1.000 kW has been done. Moreover, plant and running costs for a thermogravimetric and a Rankine cycle, 1 MW power, have been compared. Basically due to the lead charge, the plant cost of the former is higher: nevertheless such amount can be recuperated in less than three years, being higher the running cost of the latter [it

  2. Solar kerosene from H2O and CO2

    Science.gov (United States)

    Furler, P.; Marxer, D.; Scheffe, J.; Reinalda, D.; Geerlings, H.; Falter, C.; Batteiger, V.; Sizmann, A.; Steinfeld, A.

    2017-06-01

    The entire production chain for renewable kerosene obtained directly from sunlight, H2O, and CO2 is experimentally demonstrated. The key component of the production process is a high-temperature solar reactor containing a reticulated porous ceramic (RPC) structure made of ceria, which enables the splitting of H2O and CO2 via a 2-step thermochemical redox cycle. In the 1st reduction step, ceria is endo-thermally reduced using concentrated solar radiation as the energy source of process heat. In the 2nd oxidation step, nonstoichiometric ceria reacts with H2O and CO2 to form H2 and CO - syngas - which is finally converted into kerosene by the Fischer-Tropsch process. The RPC featured dual-scale porosity for enhanced heat and mass transfer: mm-size pores for volumetric radiation absorption during the reduction step and μm-size pores within its struts for fast kinetics during the oxidation step. We report on the engineering design of the solar reactor and the experimental demonstration of over 290 consecutive redox cycles for producing high-quality syngas suitable for the processing of liquid hydrocarbon fuels.

  3. Intermolecular Interactions in Ternary Glycerol–Sample–H2O

    DEFF Research Database (Denmark)

    Westh, Peter; Rasmussen, Erik Lumby; Koga, Yoshikata

    2011-01-01

    We studied the intermolecular interactions in ternary glycerol (Gly)–sample (S)–H2O systems at 25 °C. By measuring the excess partial molar enthalpy of Gly, HGlyEHEGly, we evaluated the Gly–Gly enthalpic interaction, HGly-GlyEHEGly--Gly, in the presence of various samples (S). For S, tert...... little effect on HGly-GlyEHEGly--Gly. This contrasts with our earlier studies on 1P–S–H2O in that Na+, F− and Cl− are found as hydration centers from the induced changes on HIP-IPEHEIP--IP in the presence of S, while Br−, I−, and SCN− are found to act as hydrophiles. In comparison with the Hofmeister...... ranking of these ions, the kosmotropes are hydration centers and the more kosmotropic the higher the hydration number, consistent with the original Hofmeister’s concept of “H2O withdrawing power.” Br−, I− and SCN−, on the other hand, acted as hydrophiles and the more chaotropic they are the more...

  4. Unidirectional spreading of oil under solid ice

    International Nuclear Information System (INIS)

    Weerasuriya, S.A.; Yapa, P.D.

    1993-01-01

    Equations are presented to describe the unidirectional spreading of oil under solid ice covers floating in calm water. These spreading equations are derived using a simplified form of the Navier-Stokes equations, and cover both the constant discharge and the constant volume modes. An equation for computing final slick length is also given. Laboratory experiments using physical models were conducted to verify the equations. The experiments used oils of different viscosities, ice cover roughnesses varying from smooth to rough, and a variety of discharge conditions. The emphasis of the study was on the dominant spreading mechanism for oil under ice, which is the buoyancy-viscous phase. The laboratory results agree closely with the theoretical predictions. Discrepancies can be attributed to the experimental difficulties and errors introduced from the assumptions made in deriving the theory. The equations presented will be useful in computing spreading rate during an accidental oil spill or in contingency planning. The equations are simple to use, suitable for hand calculations or for incorporation into numerical models for oil spill simulation. 24 refs., 10 figs., 1 tab

  5. Effects of H2O and H2O2 on thermal desorption of tritium from stainless steel

    International Nuclear Information System (INIS)

    Quinlan, M. J.; Shmayda, W. T.; Lim, S.; Salnikov, S.; Chambers, Z.; Pollock, E.; Schroeder, W. U.

    2008-01-01

    Tritiated stainless steel was subjected to thermal desorption at various temperatures, different temperature profiles, and in the presence of different helium carrier gas additives. In all cases the identities of the desorbing tritiated species were characterized as either water-soluble or insoluble. The samples were found to contain 1.1 mCi±0.4 mCi. Approximately ninety-five percent of this activity was released in molecular water-soluble form. Additives of H 2 O or H 2 O 2 to dry helium carrier gas increase the desorption rate and lower the maximum temperature to which the sample must be heated, in order to remove the bulk of the tritium. The measurements validate a method of decontamination of tritiated steel and suggest a technique that can be used to further explore the mechanisms of desorption from tritiated metals. (authors)

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

    Science.gov (United States)

    Kopp, E.

    1984-01-01

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

  7. Laboratory Studies of Solid CO2 Ices at Different Temperatures and Annealing Times in Support of Spitzer Space Telescope Observations

    Science.gov (United States)

    White, Douglas; Gerakines, P. A.

    2007-12-01

    The infrared absorption features of solid carbon dioxide have been detected by space observatories in nearly all lines of sight probing the dense interstellar medium (ISM). It has also been shown that the absorption feature of solid CO2 near 658 cm-1 (15.2 μm) should be a sensitive indicator of the physical conditions of the ice (e.g., temperature and composition). However, the profile structure of this feature is not well understood, and previous laboratory studies have concentrated on a limited range of temperatures and compositions for comparisons to observed spectra from both the Infrared Space Observatory and the Spitzer Space Telescope. In the laboratory study described here, the infrared spectra of ices bearing H2O, CH3OH, and CO2 have been measured with systematically varying compositions and temperatures that span the range of the values expected in the interstellar medium. The mid-infrared spectra (λ = 2.5-25 µm) were measured for 47 different ice compositions at temperatures ranging from 5 K to evaporation (at 5 K intervals). Additionally, annealing experiments of some of these ice compositions have been investigated. These data may be used to determine thermal histories of interstellar ices. This research was supported by NASA award NNG05GE44G under the Astronomy and Physics Research & Analysis Program (APRA).

  8. Ce2O3-SO3-H2O system at 150 and 200 deg C

    International Nuclear Information System (INIS)

    Belokoskov, V.I.; Trofimov, G.V.; Govorukhina, O.A.

    1978-01-01

    The solubility, solid phase composition and crystal characteristics in the Ce 2 O 3 -SO 3 -H 2 O system have been studied in a broad range of sulfuric acid concentrations (25 to 80% SO 3 ) at temperatures from 150 to 200 deg C. It has been established that in the system the equilibrium had been reached after 15 to 20 days. At 150 deg C, Ce 2 (SO 4 ) 3 x2H 2 O, Ce 2 (SO 4 ) 3 xH 2 O sulfates and Ce 2 (SO 4 ) 3 x3H 2 SO 4 acid salt crystallize in the system. At 200 deg C, the same sulfates crystallize in the system, except that the bisaturation points of the system are shifted, with respect to 150 deg C, into the region of higher SO 3 concentration and correspond to solutions with a SO 3 concentration of 57.8 and 65%. The solubility of cerium(3) at 150 deg C is about 0.5% Ce 2 O 3 . An increase in temperature up to 200 deg C leads to a slightly higher solubility of cerium sulfates

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

    OpenAIRE

    Martins, Dorival; English, Ann M.

    2014-01-01

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

  10. Synthetic, spectroscopic and structural studies on 4-aminobenzoate complexes of divalent alkaline earth metals: x-ray crystal structures of [[Mg(H2O)6] (4-aba)2].2H2O and [Ca(H2O)2(4-aba)2] (4-aba=4-aminobenzoate)

    International Nuclear Information System (INIS)

    Murugavel, Ramaswamy; Karambelkar, Vivek V.; Anantharaman, Ganapathi

    2000-01-01

    Reactions between MCl 2 .nH 2 O (M = Mg, Ca, Sr, and Ba) and 4-aminobenzoic acid (4-abaH) result in the formation of complexes [(Mg(H 2 O) 6 )(4-aba) 2 ) .2H 2 O (I), [Ca(4-aba) 2 (H2 O ) 2 ] (2), [Sr(4-aba) 2 (H2 O ) 2 ] (3), and [Ba(4-aba) 2 Cl] (4), respectively. The new compounds 1 and 2, as well as the previously reported 3 and 4 form an extended intra- and intermolecular hydrogen bonded network in the solid-state. The compounds have been characterized by elemental analysis, pH measurements, thermogravimetric studies, and IR, NMR, and UV-Vis spectroscopy. The solid state structures of the molecules 1 and 2 have been determined by single crystal x-ray diffraction studies. In the case of magnesium complex 1, the dipositively charged Mg cation is surrounded by six water molecules and the two 4-aminobenzoate ligands show no direct bonding to the metal ion. The calcium ion in 2 is octa-coordinated with direct coordination of the 4-aminobenzoate ligands to the metal ion. The Ca-Ca separation in the polymeric chain of 2 is 3.9047(5) A. (author)

  11. H2O maser flare in Orion A

    International Nuclear Information System (INIS)

    Matveenko, L.I.; Moran, J.M.; Genzel, R.

    1982-01-01

    The flare of H 2 O maser emission in Orion A was observed with the Crimea--Effelsberg and Haystack--Green Bank interferometers in November 1979. Its position is α = 5/sup h/32/sup m/46/sup s/.6 +- 0/sup s/.06, delta = -5 0 24'.28''.7 +- 1'' (1950.0); its radial velocity, 8 km/sec. The asymmetric line profile has a 28-kHz halfwidth. The flare source comprises a 0''.0005 core (T/sub b/ = 5 x 10 16 0 K) embedded in a 0''.005 halo (T/sub b/ = 3 x 10 14 0 K)

  12. Structure and thermal property of N,N-diethyl-N-methyl-N-2-methoxyethyl ammonium tetrafluoroborate-H2O mixtures

    International Nuclear Information System (INIS)

    Imai, Yusuke; Abe, Hiroshi; Goto, Takefumi; Yoshimura, Yukihiro; Michishita, Yosuke; Matsumoto, Hitoshi

    2008-01-01

    By in situ observations using simultaneous X-ray diffraction and differential scanning calorimetry method, complicated phase transitions were observed in N,N-diethyl-N-methyl-N-2-methoxyethyl ammonium tetrafluoroborate, [DEME][BF 4 ] and H 2 O mixtures. In pure [DEME][BF 4 ], two different crystal structures were determined below crystallization temperature, T c . Two kinds of crystals correspond to two stages of melting upon heating. T c decreases with increasing in the H 2 O content of [DEME][BF 4 ]-H 2 O mixture. Around 6.7 mol% H 2 O, an amorphous solid, however, was formed without crystallization on cooling. Glass transition temperature, T g , of the amorphous phase depends on cooling rate of the mixture. On heating, the amorphous solid transformed to a crystal accompanied by an exothermal peak. This unusual cold crystallization is induced by H 2 O molecules. Two different dynamic components were observed in a Raman spectrum of the amorphous phase, where the lower Raman band is crystal-like and the higher one is liquid-like. At higher H 2 O concentration, coexistence of the amorphous solid and crystal was realized below T c , and the cold crystallization also occurred. In spite of a variety of phase transitions, the crystal structure of [DEME][BF 4 ]-H 2 O mixtures is the same one as pure [DEME][BF 4

  13. Study of the effect of pressure on electrolysis of H2O and co-electrolysis of H2O and CO2 at high temperature

    International Nuclear Information System (INIS)

    Bernadet, Lucile

    2016-01-01

    This thesis work investigates the behavior of a solid oxide cell operating under pressure in high temperature steam electrolysis and co-electrolysis mode (H 2 O and CO 2 ). The experimental study of single cell associated with the development of multi-physical models have been set up. The experiments, carried out using an original test bench developed by the CEA-Grenoble on two types of cells between 1 and 10 bar and 700 to 800 C, allowed to identify in both operating modes that the pressure has a positive or negative effect on performance depending on the cell operating point (current, voltage). In addition, gas analyzes performed in co-electrolysis led to detect in situ CH 4 production under pressure. These pressure effects were simulated by models calibrated at atmospheric pressure. Simulations analysis helped identify the pressure dependent mechanisms and propose operating conditions thanks to the establishment of operating maps. (author) [fr

  14. Evolution of H2O, CO, and CO2 production in Comet C/2009 P1 Garradd during the 2011-2012 apparition

    Science.gov (United States)

    McKay, Adam J.; Cochran, Anita L.; DiSanti, Michael A.; Villanueva, Geronimo; Russo, Neil Dello; Vervack, Ronald J.; Morgenthaler, Jeffrey P.; Harris, Walter M.; Chanover, Nancy J.

    2015-04-01

    We present analysis of high spectral resolution NIR spectra of CO and H2O in Comet C/2009 P1 (Garradd) taken during its 2011-2012 apparition with the CSHELL instrument on NASA's Infrared Telescope Facility (IRTF). We also present analysis of observations of atomic oxygen in Comet Garradd obtained with the ARCES echelle spectrometer mounted on the ARC 3.5-m telescope at Apache Point Observatory and the Tull Coude spectrograph on the Harlan J. Smith 2.7-m telescope at McDonald Observatory. The observations of atomic oxygen serve as a proxy for H2O and CO2. We confirm the high CO abundance in Comet Garradd and the asymmetry in the CO/H2O ratio with respect to perihelion reported by previous studies. From the oxygen observations, we infer that the CO2/H2O ratio decreased as the comet moved towards the Sun, which is expected based on current sublimation models. We also infer that the CO2/H2O ratio was higher pre-perihelion than post-perihelion. We observe evidence for the icy grain source of H2O reported by several studies pre-perihelion, and argue that this source is significantly less abundant post-perihelion. Since H2O, CO2, and CO are the primary ices in comets, they drive the activity. We use our measurements of these important volatiles in an attempt to explain the evolution of Garradd's activity over the apparition.

  15. Utilization of membranes for H2O recycle system

    Science.gov (United States)

    Ohya, H.; Oguchi, M.

    1986-01-01

    Conceptual studies of closed ecological life support systems (CELSS) carried out at NAL in Japan for a water recycle system using membranes are reviewed. The system will treat water from shower room, urine, impure condensation from gas recycle system, and so on. The H2O recycle system is composed of prefilter, ultrafiltration membrane, reverse osmosis membrane, and distillator. Some results are shown for a bullet train of toilet-flushing water recycle equipment with an ultraviltration membrane module. The constant value of the permeation rate with a 4.7 square meters of module is about 70 1/h after 500th of operation. Thermovaporization with porous polytetrafluorocarbon membrane is also proposed to replce the distillator.

  16. Fabry-Perot observations of Comet Halley H2O(+)

    International Nuclear Information System (INIS)

    Scherb, F.; Roesler, F.L.D.; Harlander, J.; Magee-sauer, K.

    1990-01-01

    Fabry-Perot scanning spectrometer observations of Comet Halley's H 2 O(+) emissions have yielded 6158.64 and 6158.85 A spin doublet data at distances in the range of 0 to 2 million km from the comet heat in the antisunward direction. Cometary plasma outflow velocities were ascertained on the basis of the emissions' Doppler shifts, yielding results that were mostly but not exclusively consistent with the plasma's constant antisunward acceleration; the acceleration varied from night to night of observations over a 30-300 cm/sec range. The unusual plasma kinematics of December 14-15, 1985, and January 10, 1986, may be associated with the tail-disconnection activity observed by others. 30 refs

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

    International Nuclear Information System (INIS)

    Gao Xizhen

    1997-05-01

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

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

    Directory of Open Access Journals (Sweden)

    Nezamaddin Daneshvar

    2007-03-01

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

  19. I + (H2O)2 → HI + (H2O)OH Forward and Reverse Reactions. CCSD(T) Studies Including Spin-Orbit Coupling.

    Science.gov (United States)

    Wang, Hui; Li, Guoliang; Li, Qian-Shu; Xie, Yaoming; Schaefer, Henry F

    2016-03-03

    The potential energy profile for the atomic iodine plus water dimer reaction I + (H2O)2 → HI + (H2O)OH has been explored using the "Gold Standard" CCSD(T) method with quadruple-ζ correlation-consistent basis sets. The corresponding information for the reverse reaction HI + (H2O)OH → I + (H2O)2 is also derived. Both zero-point vibrational energies (ZPVEs) and spin-orbit (SO) coupling are considered, and these notably alter the classical energetics. On the basis of the CCSD(T)/cc-pVQZ-PP results, including ZPVE and SO coupling, the forward reaction is found to be endothermic by 47.4 kcal/mol, implying a significant exothermicity for the reverse reaction. The entrance complex I···(H2O)2 is bound by 1.8 kcal/mol, and this dissociation energy is significantly affected by SO coupling. The reaction barrier lies 45.1 kcal/mol higher than the reactants. The exit complex HI···(H2O)OH is bound by 3.0 kcal/mol relative to the asymptotic limit. At every level of theory, the reverse reaction HI + (H2O)OH → I + (H2O)2 proceeds without a barrier. Compared with the analogous water monomer reaction I + H2O → HI + OH, the additional water molecule reduces the relative energies of the entrance stationary point, transition state, and exit complex by 3-5 kcal/mol. The I + (H2O)2 reaction is related to the valence isoelectronic bromine and chlorine reactions but is distinctly different from the F + (H2O)2 system.

  20. Structural study of CH4, CO2 and H2O clusters containing from several tens to several thousands of molecules

    Science.gov (United States)

    Torchet, G.; Farges, J.; de Feraudy, M. F.; Raoult, B.

    Clusters are produced during the free jet expansion of gaseous CH4, CO2 or H2O. For a given stagnation temperature To, the mean cluster size is easily increased by increasing the stagnation pressure p0. On the other hand, the cluster temperature does not depend on stagnation conditions but mainly on properties of the condensed gas. An electron diffraction analysis provides information about the cluster structure. Depending on whether the diffraction patterns exhibit crystalline lines or not, the structure is worked out either by using crystallographic methods or by constructing cluster models. When they contain more than a few thousand molecules, clusters show a crystalline structure identical to that of one phase, namely, the cubic phase, known in bulk solid: plastic phase (CH4), unique solid phase (CO2) or metastable cubic phase (H2O). When decreasing the cluster size, the studied compounds behave quite differently: CO2 clusters keep the same crystalline structure, CH4 clusters show the multilayer icosahedral structure wich has been found in rare gas clusters, and H2O clusters adopt a disordered structure different from the amorphous structures of bulk ice. Des agrégats sont produits au cours de la détente en jet libre des gaz CH4, CO2 ou H2O. Pour une température initiale donnée To, on accroît facilement la taille moyenne des agrégats en augmentant la pression initiale po . Par contre, la température des agrégats dépend principalement des propriétés du gaz condensé. Une analyse par diffraction électronique permet l'étude de la structure des agrégats. Selon que les diagrammes de diffraction contiennent ou non des raies cristallines, on a recours soit à des méthodes cristallographiques soit à la construction de modèles d'agrégats. Lorsqu'ils renferment plus de quelques milliers de molécules, les agrégats adoptent la structure cristalline de l'une des phases connues du solide massif et plus précisément la phase cubique : phase plastique pour

  1. Nanoparticle formation in H2O/N-2 and H2O/Ar mixtures under irradiation by 20 MeV protons and positive corona discharge

    DEFF Research Database (Denmark)

    Imanaka, M.; Tomita, S.; Kanda, S.

    2010-01-01

    To investigate the contribution of ions to gas nucleation, we have performed experiments on the formation of water droplets in H2O/N-2 and H2O/Ar gas mixtures by irradiation with a 20 MeV proton beam and by positive corona discharge. The size of the formed nanoparticles was measured using...

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

    NARCIS (Netherlands)

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

    2013-01-01

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

  3. Interpretation of the H2O maser outbursts in Orion

    International Nuclear Information System (INIS)

    Strel'nitskij, V.S.

    1982-01-01

    It is shown, that the H 2 O maser that flared up in Orion (+8 km/s) was partly unsaturated. The anti-correlation between the line width and intensity, the asymmetry of the profile and the changes of the visibility function within it are explained by blending of two componenets, one of which has experienced a flare. From the observed polarization properties the upper limit to the electron density (nsub(e) 5 cm -3 ), the strength of the magnetic field (B approximately 10 -2 G) and its direction (position angle phi approximately -15 deg) within the source are deduced. According to the proposed physical model the source is a gas condensation, pressed, heated and accelerated by the strong stellar wind from a young star (possibly IRc4). The maser is pumped by the CCr-process at sup(n)H approximately 10 11 -10 12 cm -3 . If the condensation is a remnant of a circumstellar gas-dust disk, the magnetic field within the disk must be essentially azimuthal [ru

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

    Science.gov (United States)

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

    1982-01-01

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

  5. Exergetic and energetic comparison of LiCl-H_2O and LiBr-H_2O working pairs in a solar absorption cooling system

    International Nuclear Information System (INIS)

    Bellos, Evangelos; Tzivanidis, Christos; Antonopoulos, Kimon A.

    2016-01-01

    Highlights: • Two working pairs (LiCl-H_2O and LiBr-H_2O) are examined in a solar absorption chiller. • The examined single effect absorption chiller is driven by flat plate collectors. • The system is analyzed energetically and energetically for 3 ambient temperatures. • LiCl-H_2O performs better than LiBr-H_2O in all the examined cases. • The optimum operating temperature is lower for the case of pair LiCl-H_2O. - Abstract: The objective of this study is to investigate the use of an alternative working pair in a solar absorption cooling system. LiCl-H_2O is the new examined pair and it is compared energetically and exegetically with the conventional pair LiBr-H_2O, which is the most usual in air-conditioning applications. The simplest solar cooling system is analyzed in order to focus in the comparison between these working fluids. Specifically, flat plate collectors, coupled with a storage tank, feed the single effect absorption chiller which produces 250 kW cooling at 10 °C. The two pairs are examined parametrically for various heat source temperature levels and for three ambient temperature levels (25 °C, 30 °C and 35 °C). The minimization of the collecting area, which means maximum exergetic efficiency, is the optimization goal in every case. The final results show that LiCl-H_2O pair performs better in all cases by giving greater exergetic efficiency. More specifically, about 8% lower collecting area is required to cover the demanded cooling load with this working pair. Another interesting result is that the optimum heat source temperature for the LiCl-H_2O is roughly lower than the respective for the LiBr-H_2O. The system is analyzed in steady state with the commercial software Engineering Equator Solver (EES).

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

    Directory of Open Access Journals (Sweden)

    Saavedra del Aguila Juan

    2015-01-01

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

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

    Directory of Open Access Journals (Sweden)

    ALTAF ALAM NOONARI

    2017-01-01

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

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

    Science.gov (United States)

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

    2016-01-01

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

  9. Crystal structures of ZnCl2·2.5H2O, ZnCl2·3H2O and ZnCl2·4.5H2O

    Directory of Open Access Journals (Sweden)

    Erik Hennings

    2014-12-01

    Full Text Available The formation of different complexes in aqueous solutions is an important step in understanding the behavior of zinc chloride in water. The structure of concentrated ZnCl2 solutions is governed by coordination competition of Cl− and H2O around Zn2+. According to the solid–liquid phase diagram, the title compounds were crystallized below room temperature. The structure of ZnCl2·2.5H2O contains Zn2+ both in a tetrahedral coordination with Cl− and in an octahedral environment defined by five water molecules and one Cl− shared with the [ZnCl4]2− unit. Thus, these two different types of Zn2+ cations form isolated units with composition [Zn2Cl4(H2O5] (pentaaqua-μ-chlorido-trichloridodizinc. The trihydrate {hexaaquazinc tetrachloridozinc, [Zn(H2O6][ZnCl4]}, consists of three different Zn2+ cations, one of which is tetrahedrally coordinated by four Cl− anions. The two other Zn2+ cations are each located on an inversion centre and are octahedrally surrounded by water molecules. The [ZnCl4] tetrahedra and [Zn(H2O6] octahedra are arranged in alternating rows parallel to [001]. The structure of the 4.5-hydrate {hexaaquazinc tetrachloridozinc trihydrate, [Zn(H2O6][ZnCl4]·3H2O}, consists of isolated octahedral [Zn(H2O6] and tetrahedral [ZnCl4] units, as well as additional lattice water molecules. O—H...O hydrogen bonds between the water molecules as donor and ZnCl4 tetrahedra and water molecules as acceptor groups leads to the formation of a three-dimensional network in each of the three structures.

  10. Ultrafast phosphate hydration dynamics in bulk H2O

    International Nuclear Information System (INIS)

    Costard, Rene; Tyborski, Tobias; Fingerhut, Benjamin P.; Elsaesser, Thomas

    2015-01-01

    Phosphate vibrations serve as local probes of hydrogen bonding and structural fluctuations of hydration shells around ions. Interactions of H 2 PO 4 − ions and their aqueous environment are studied combining femtosecond 2D infrared spectroscopy, ab-initio calculations, and hybrid quantum-classical molecular dynamics (MD) simulations. Two-dimensional infrared spectra of the symmetric (ν S (PO 2 − )) and asymmetric (ν AS (PO 2 − )) PO 2 − stretching vibrations display nearly homogeneous lineshapes and pronounced anharmonic couplings between the two modes and with the δ(P-(OH) 2 ) bending modes. The frequency-time correlation function derived from the 2D spectra consists of a predominant 50 fs decay and a weak constant component accounting for a residual inhomogeneous broadening. MD simulations show that the fluctuating electric field of the aqueous environment induces strong fluctuations of the ν S (PO 2 − ) and ν AS (PO 2 − ) transition frequencies with larger frequency excursions for ν AS (PO 2 − ). The calculated frequency-time correlation function is in good agreement with the experiment. The ν(PO 2 − ) frequencies are mainly determined by polarization contributions induced by electrostatic phosphate-water interactions. H 2 PO 4 − /H 2 O cluster calculations reveal substantial frequency shifts and mode mixing with increasing hydration. Predicted phosphate-water hydrogen bond (HB) lifetimes have values on the order of 10 ps, substantially longer than water-water HB lifetimes. The ultrafast phosphate-water interactions observed here are in marked contrast to hydration dynamics of phospholipids where a quasi-static inhomogeneous broadening of phosphate vibrations suggests minor structural fluctuations of interfacial water

  11. Ultrafast phosphate hydration dynamics in bulk H2O

    Science.gov (United States)

    Costard, Rene; Tyborski, Tobias; Fingerhut, Benjamin P.; Elsaesser, Thomas

    2015-06-01

    Phosphate vibrations serve as local probes of hydrogen bonding and structural fluctuations of hydration shells around ions. Interactions of H2PO4- ions and their aqueous environment are studied combining femtosecond 2D infrared spectroscopy, ab-initio calculations, and hybrid quantum-classical molecular dynamics (MD) simulations. Two-dimensional infrared spectra of the symmetric ( ν S ( PO2 - ) ) and asymmetric ( ν A S ( PO2 - ) ) PO 2- stretching vibrations display nearly homogeneous lineshapes and pronounced anharmonic couplings between the two modes and with the δ(P-(OH)2) bending modes. The frequency-time correlation function derived from the 2D spectra consists of a predominant 50 fs decay and a weak constant component accounting for a residual inhomogeneous broadening. MD simulations show that the fluctuating electric field of the aqueous environment induces strong fluctuations of the ν S ( PO2 - ) and ν A S ( PO2 - ) transition frequencies with larger frequency excursions for ν A S ( PO2 - ) . The calculated frequency-time correlation function is in good agreement with the experiment. The ν ( PO2 - ) frequencies are mainly determined by polarization contributions induced by electrostatic phosphate-water interactions. H2PO4-/H2O cluster calculations reveal substantial frequency shifts and mode mixing with increasing hydration. Predicted phosphate-water hydrogen bond (HB) lifetimes have values on the order of 10 ps, substantially longer than water-water HB lifetimes. The ultrafast phosphate-water interactions observed here are in marked contrast to hydration dynamics of phospholipids where a quasi-static inhomogeneous broadening of phosphate vibrations suggests minor structural fluctuations of interfacial water.

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

    Directory of Open Access Journals (Sweden)

    Nazari Shahram

    2013-08-01

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

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

    Science.gov (United States)

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

    2017-07-27

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

  14. Separating NaCl and AlCl3·6H2O Crystals from Acidic Solution Assisted by the Non-Equilibrium Phase Diagram of AlCl3-NaCl-H2O(-HCl Salt-Water System at 353.15 K

    Directory of Open Access Journals (Sweden)

    Huaigang Cheng

    2017-08-01

    Full Text Available Extracting AlCl3·6H2O from acid leaching solution through crystallization is one of the key processes to extracting aluminum from fly ash, coal gangue and other industrial solid wastes. However, the obtained products usually have low purity and a key problem is the lack of accurate data for phase equilibrium. This paper presented the non-equilibrium phase diagrams of AlCl3-NaCl-H2O (HCl salt-water systems under continuous heating and evaporation conditions, which were the main components of the acid leaching solution obtained through a sodium-assisted activation hydrochloric acid leaching process. The ternary system was of a simple eutonic type under different acidities. There were three crystalline regions; the crystalline regions of AlCl3·6H2O, NaCl and the mixture AlCl3·6H2O/NaCl, respectively. The phase diagram was used to optimize the crystallization process of AlCl3·6H2O and NaCl. A process was designed to evaporate and remove NaCl at the first stage of the evaporation process, and then continue to evaporate and crystallize AlCl3·6H2O after solid-liquid separation. The purities of the final salt products were 99.12% for NaCl and up to 97.35% for AlCl3·6H2O, respectively.

  15. Solubility of NaNd(CO3)2.6H2O(c) in concentrated Na2CO3 and NaHCO3 solutions

    International Nuclear Information System (INIS)

    Rao, L.; Rai, D.; Felmy, A.R.; Fulton, R.W.; Novak, C.F.

    1996-01-01

    NaNd(CO 3 ) 2 x 6 H 2 O(c) was identified to be the final equilibrium solid phase in suspensions containing concentrated sodium carbonate (0.1 to 2.0 M) and sodium bicarbonate (0.1 to 1.0 M), with either NaNd(CO 3 ) 2 x 6 H 2 O(c) or Nd 2 (CO 3 ) 3 x xH 2 O(s) as initial solids. A thermodynamic model, based on Pitzer's specific into-interaction approach, was developed to interpret the solubility of NaNd(CO 3 ) 2 x 6 H 2 O(c) as functions of sodium carbonate and sodium bicarbonate concentrations. In this model, the solubility data of NaNd(CO 3 ) 2 x 6 H 2 O(c) were explained by assuming the formation of NdCO 3 + , Nd(CO 3 ) 2 - and Nd(CO 3 ) 3 3- species and invoking the specific ion interactions between Na + and Nd(CO 3 ) 3 3- . Ion interaction parameters for Na + -Nd(CO 3 ) 3 3- were developed to fit the solubility data. Based on the model calculations, Nd(CO 3 ) 3 3- was the predominant aqueous neodymium species in 0.1 to 2 M sodium carbonate and 0.1 to 1 M sodium bicarbonate solutions. The logarithm of the NaNd(CO 3 ) 2 x 6 H 2 O solubility product (NaNd(CO 3 ) 2 x 6 H 2 O(c)=Na + +Nd 3+ +2 CO 3 2- +6 H 2 O) was calculated to be -21.39. This model also provided satisfactory interpretation of the solubility data of the analogous Am(III) system in less concentrated carbonate and bicarbonate solutions. (orig.)

  16. Physicochemical properties of the CsNO2-CsOH-H2O ternary system at 25 deg C

    International Nuclear Information System (INIS)

    Protsenko, P.I.; Medvedev, B.S.; Popova, T.B.

    1977-01-01

    Saturated solutions of the CsNO 2 - CsOH- H 2 O system have been studied at 25 deg C by the methods of solubility, viscosity, electric conductivity, refractometry and density. It is stated that no solid phase of a new composition is formed in the system. While adding hydroxide to the saturated solution of cesium nitride, a considerable salting-out of the latter takes place

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

    International Nuclear Information System (INIS)

    Song, Taek Ho

    1994-02-01

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

  18. Measurements of the Activity of dissolved H2O in an Andesite Melt

    Science.gov (United States)

    Moore, G. M.; Touran, J. P.; Pu, X.; Kelley, K. A.; Cottrell, E.; Ghiorso, M. S.

    2016-12-01

    The large effect of dissolved H2O on the physical and chemical nature of silicate melts, and its role in driving volcanism, is well known and underscores the importance of this volatile component. A complete understanding of the chemical behavior of dissolved H2O in silicate melts requires the quantification of its thermodynamic activity as a function of pressure, temperature, and melt composition, particularly at low H2O contents (i.e. at under-saturated conditions). Knowledge of the activity of H2O in silicate melts at H2O-undersaturated conditions will improve our understanding of hydrous phase equilibria, as well as our models of physical melt properties. Measurement of the activity of any silicate melt component, much less that of a volatile component such as H2O, is a difficult experimental task however. By using a modified double capsule design (Matjuschkin et al, 2015) to control oxygen fugacity in piston cylinder experiments, along with high precision X-ray absorption techniques (XANES) to measure iron oxidation state in silicate glasses (Cottrell et al, 2009), we are able to constrain the H2O activity in silicate melts at under-saturated conditions. Preliminary results on an andesite melt with low H2O content (3 wt%) have been shown (Moore et al, 2016) to match predicted H2O activity values calculated using the H2O equation of state of Duan and Zhang (1996) and the H2O solubility model of Ghiorso and Gualda (2015). More recent results on the same andesite melt containing approximately 5 wt% H2O however show a large negative deviation from the predicted values. Reversal experiments involving an oxidized starting material are ongoing, as well as further characterization of the samples to detect the presence of possible contaminants that would induce reduction of the melt beyond that related to the H2O activity (e.g. graphite contamination).

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

    Science.gov (United States)

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

    2018-03-01

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

  20. Vibrational spectroscopy of NO + (H2O)n: Evidence for the intracluster reaction NO + (H2O)n --> H3O + (H2O)n - 2 (HONO) at n => 4

    Science.gov (United States)

    Choi, Jong-Ho; Kuwata, Keith T.; Haas, Bernd-Michael; Cao, Yibin; Johnson, Matthew S.; Okumura, Mitchio

    1994-05-01

    Infrared spectra of mass-selected clusters NO+(H2O)n for n=1 to 5 were recorded from 2700 to 3800 cm-1 by vibrational predissociation spectroscopy. Vibrational frequencies and intensities were also calculated for n=1 and 2 at the second-order Møller-Plesset (MP2) level, to aid in the interpretation of the spectra, and at the singles and doubles coupled cluster (CCSD) level energies of n=1 isomers were computed at the MP2 geometries. The smaller clusters (n=1 to 3) were complexes of H2O ligands bound to a nitrosonium ion NO+ core. They possessed perturbed H2O stretch bands and dissociated by loss of H2O. The H2O antisymmetric stretch was absent in n=1 and gradually increased in intensity with n. In the n=4 clusters, we found evidence for the beginning of a second solvation shell as well as the onset of an intracluster reaction that formed HONO. These clusters exhibited additional weak, broad bands between 3200 and 3400 cm-1 and two new minor photodissociation channels, loss of HONO and loss of two H2O molecules. The reaction appeared to go to completion within the n=5 clusters. The primary dissociation channel was loss of HONO, and seven vibrational bands were observed. From an analysis of the spectrum, we concluded that the n=5 cluster rearranged to form H3O+(H2O)3(HONO), i.e., an adduct of the reaction products.

  1. Ab initio studies of O2-(H2O)n and O3-(H2O)n anionic molecular clusters, n≤12

    DEFF Research Database (Denmark)

    Bork, Nicolai Christian; Kurtén, T.; Enghoff, Martin Andreas Bødker

    2011-01-01

    that anionic O2−(H2O)n and O3−(H2O)n clusters are thermally stabilized at typical atmospheric conditions for at least n = 5. The first 4 water molecules are strongly bound to the anion due to delocalization of the excess charge while stabilization of more than 4 H2O is due to normal hydrogen bonding. Although...... clustering up to 12 H2O, we find that the O2 and O3 anions retain at least ca. 80 % of the charge and are located at the surface of the cluster. The O2− and O3− speicies are thus accessible for further reactions. Finally, the thermodynamics of a few relevant cluster reactions are considered....

  2. Ab initio studies of O-2(-) (H2O)(n) and O-3(-) (H2O)(n) anionic molecular clusters, n

    DEFF Research Database (Denmark)

    Bork, Nicolai Christian; Kurten, T.; Enghoff, Martin Andreas Bødker

    2011-01-01

    that anionic O-2(-)(H2O)n and O-3(-)(H2O)n clusters are thermally stabilized at typical atmospheric conditions for at least n = 5. The first 4 water molecules are strongly bound to the anion due to delocalization of the excess charge while stabilization of more than 4 H2O is due to normal hydrogen bonding....... Although clustering up to 12 H2O, we find that the O-2 and O-3 anions retain at least ca. 80 % of the charge and are located at the surface of the cluster. The O-2(-) and O-3(-) speicies are thus accessible for further reactions. We consider the distributions of cluster sizes as function of altitude before...

  3. Experimental studies on cycling stable characteristics of inorganic phase change material CaCl2·6H2O-MgCl2·6H2O modified with SrCl2·6H2O and CMC

    Science.gov (United States)

    He, Meizhi; Yang, Luwei; Zhang, Zhentao

    2018-01-01

    By means of mass ratio method, binary eutectic hydrated salts inorganic phase change thermal energy storage system CaCl2·6H2O-20wt% MgCl2·6H2O was prepared, and through adding nucleating agent 1wt% SrCl2·6H2O and thickening agent 0.5wt% carboxy methyl cellulose (CMC), inoganic phase change material (PCM) modified was obtained. With recording cooling-melting curves simultaneously, this PCM was frozen and melted for 100 cycles under programmable temperature control. After per 10 cycles, the PCM was charaterized by differential scanning calorimeter (DSC), X-ray diffraction (XRD) and density meter, then analysing variation characteristics of phase change temperature, supercooling degree, superheat degree, latent heat, crystal structure and density with the increase of cycle index. The results showed that the average values of average phase change temperature for cooling and heating process were 25.70°C and 27.39°C respectively with small changes. The average values of average supercooling and superheat degree were 0.59°C and 0.49°C respectively, and the maximum value was 1.10°C. The average value and standard deviation of latent heat of fusion were 120.62 J/g and 1.90 J/g respectively. Non-molten white solid sediments resulted from phase separation were tachyhydrite (CaMg2Cl6·12H2O), which was characterized by XRD. Measuring density of the PCM after per 10 cycles, and the results suggested that the total mass of tachyhydrite was limited. In summary, such modified inoganic PCM CaCl2·6H2O-20wt% MgCl2·6H2O-1wt% SrCl2·6H2O-0.5wt% CMC could stay excellent circulation stability within 100 cycles, and providing reference value in practical use.

  4. Crystal structure of strontium aqua(ethylenediaminetetraacetato)cobaltate(II) tetrahydrate Sr[CoEdta(H2O)] · 4H2O

    International Nuclear Information System (INIS)

    Zasurskaya, L.A.; Polynova, T.N.; Polyakova, I.N.; Sergienko, V.S.; Poznyak, A.L.

    2001-01-01

    The complex Sr[Co II Edta] · 5H 2 O (I) (where Edta 4- is the ethylenediaminetetraacetate ion) has been synthesized. The crystal structure of this compound is determined by X-ray diffraction. Crystals are monoclinic, a = 7.906(2) A, b = 12.768(2) A, c = 18.254(3) A, β = 95.30(3) deg., V 1834.8 A 3 , space group P2 1 /n, Z = 4, and R = 0.036. The structure is built up of the binuclear complex fragments {Sr(H 2 O) 3 [CoEdta(H 2 O)]}, which consist of the anionic [CoEdta(H 2 O)] 2- and cationic [Sr(H 2 O) 3 ] 2+ units linked by the Sr-O bonds into a three-dimensional framework. The coordination polyhedra of the Co and Sr atoms are mono- and bicapped trigonal prisms. The coordination sphere of the Co atom (the coordination number is equal to 6 + 1) involves six donor atoms (2N and 4O) of the Edta 4- ligand and the O w atom of water molecule. One of the Co-O distances (2.718 A) is considerably longer than the other Co-O lig distances (2.092-2.190 A) and the Co-O w (1) distance (2.079 A). The Sr coordination polyhedron (the coordination number is eight) contains three water molecules, three carbonyl O atoms of the three different anionic complexes, and two O atoms of one acetate group of the fourth anionic complex. The Sr-O distances fall in the range 2.535-2.674 A. The structural formula of the compound is {Sr(H 2 O) 3 [CoEdta(H 2 O)]} 3∞ · H 2 O

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

    Science.gov (United States)

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

    2003-01-01

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

  6. The correlation between HCN/H2O flux ratios and disk mass: evidence for protoplanet formation

    Science.gov (United States)

    Rose, Caitlin; Salyk, Colette

    2017-01-01

    We analyze hydrogen cyanide (HCN) and water vapor flux ratios in protoplanetary disks as a way to trace planet formation. Analyzing only disks in the Taurus molecular cloud, Najita et al. (2013) found a tentative correlation between protoplanetary disk mass and the HCN/H2O line flux ratio in Spitzer-IRS emission spectra. They interpret this correlation to be a consequence of more massive disks forming planetesimals more efficiently than smaller disks, as the formation of large planetesimals may lock up water ice in the cool outer disk region and prevent it from migrating, drying out the inner disk. The sequestering of water (and therefore oxygen) in the outer disk may also increase the carbon-to- oxygen ratio in the inner disk, leading to enhanced organic molecule (e.g. HCN) emission. To confirm this trend, we expand the Najita et al. sample by calculating HCN/H2O line flux ratios for 8 more sources with known disk masses from clusters besides Taurus. We find agreement with the Najita et al. trend, suggesting that this is a widespread phenomenon. In addition, we find HCN/H2O line flux ratios for 17 more sources that await disk mass measurements, which should become commonplace in the ALMA era. Finally, we investigate linear fits and outliers to this trend, and discuss possible causes.

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

    Science.gov (United States)

    Xu, Yifan; Itzek, Andreas

    2014-01-01

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

  8. Absolute linestrengths in the H2O2 nu6 band

    Science.gov (United States)

    May, Randy D.

    1991-01-01

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

  9. 40 CFR 1065.370 - CLD CO2 and H2O quench verification.

    Science.gov (United States)

    2010-07-01

    ... 40 Protection of Environment 32 2010-07-01 2010-07-01 false CLD CO2 and H2O quench verification....370 CLD CO2 and H2O quench verification. (a) Scope and frequency. If you use a CLD analyzer to measure NOX, verify the amount of H2O and CO2 quench after installing the CLD analyzer and after major...

  10. Syntheses and Thermal Behaviors of Rb(FOX-7)·H2O and Cs(FOX-7)·H2O

    International Nuclear Information System (INIS)

    Luo, Jinan; Xu, Kangzhen; Wang, Min; Ren, Xiaolei; Chen, Yongshun; Song, Jirong; Zhao, Fengqi

    2010-01-01

    Two new energetic organic alkali metal salts, 1,1-diamino-2,2-dinitroethylene rubidium salt [Rb(FOX-7)·H 2 O] and 1,1- diamino-2,2-dinitroethylene cesium salt [Cs(FOX-7)·H 2 O], were synthesized by reacting of 1,1-diamino-2,2-dinitroethylene (FOX-7) and rubidium chloride or cesium chloride in alkali methanol aqueous solution, respectively. The thermal behaviors of Rb(FOX-7)·H 2 O and Cs(FOX-7)·H 2 O were studied with DSC and TG methods. The critical temperatures of thermal explosion of the two compounds are 216.22 and 223.73 .deg. C, respectively. Specific heat capacities of the two compounds were determined with a micro-DSC method, and the molar heat capacities are 217.46 and 199.47 J mol -1 K -1 at 298.15 K, respectively. The adiabatic times-to-explosion were also calculated to be a certain value of 5.81 - 6.36 s for Rb(FOX-7)·H 2 O, and 9.92 - 10.54 s for Cs(FOX-7)·H 2 O. After FOX-7 becoming alkali metal salts, thermal decomposition temperatures of the compounds heighten with the rise of element period, but thermal decomposition processes become intense

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

    International Nuclear Information System (INIS)

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

    1995-01-01

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

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

    Science.gov (United States)

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

    2018-03-01

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

  13. Mesospheric H2O Concentrations Retrieved from SABER/TIMED Measurements

    Science.gov (United States)

    Feofilov, A. G.; Marshall, B. T.; Garcia-Comas, M.; Kutepov, A. A.; Lopez-Puertas, M.; Manuilova, R. O.; Yankovsky, V.A.; Goldberg, R. A.; Gordley, L. L.; Petelin, S.; hide

    2008-01-01

    The SABER instrument on board the TIMED Satellite is a limb scanning infrared radiometer designed to measure temperature and minor constituent vertical profiles and energetics parameters in the mesosphere and lower thermosphere (MLT). The H2O concentrations are retrieved from 6.3 micron band radiances. The populations of H2O(v2) vibrational levels are in non-Local Thermodynamic Equilibrium (non-LTE) above approximately 55 km altitude and the interpretation of 6.3 micron radiance requires utilizing non-LTE H2O model that includes various energy exchange processes in the system of H2O vibrational levels coupled with O2, N2, and CO2 vibrational levels. We incorporated these processes including kinetics of O2/O3 photolysis products to our research non-LTE H2O model and applied it for the development and optimization of SABER operational model. The latter has been validated using simultaneous SCISAT1/ACE occultation measurements. This helped us to estimate CO2(020)-O2(X,v=I), O2(X,v=I)- H2O(010), and O2(X,v=1) O rates at mesopause temperatures that is critical for an adequate interpretation of non-LTE H2O radiances in the MLT. The first distributions of seasonal and meridional H2O concentrations retrieved from SABER 6.3 micron radiances applying an updated non-LTE H2O model are demonstrated and discussed.

  14. Enhanced Cr(VI) removal from groundwater by Fe0-H2O system with bio-amended iron corrosion

    DEFF Research Database (Denmark)

    Yin, Weizhao; Li, Yongtao; Wu, Jinhua

    2017-01-01

    Abstract A one-pot bio-iron system was established to investigate synergetic abiotic and biotic effects between iron and microorganisms on Cr(VI) removal. More diverse iron corrosion and reactive solids, such as green rusts, lepidocrocite and magnetite were found in the bio-iron system than...... transfer on the solid phase. The results also showed that the reduction of Cr(VI) by microorganisms was insignificant, indicating the adsorption/co-precipitation of Cr by iron oxides on iron surface was responsible for the overall Cr(VI) removal. Our study demonstrated that the bio-amended iron corrosion...... in the Fe0-H2O system, leading to 4.3 times higher Cr(VI) removal efficiency in the bio-iron system than in the Fe0-H2O system. The cycling experiment also showed that the Cr(VI) removal capacity of Fe0 in the bio-iron system was 12.4 times higher than that in the Fe0-H2O system. A 62 days of life...

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

    Directory of Open Access Journals (Sweden)

    Aili Li

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

  16. Vibrational spectroscopy of NO^+(H_2O)_n: Evidence for the intracluster reaction NO^+(H_2O)_n→H_3O^+(H_2O)_(n-2)(HONO) at n≥4

    OpenAIRE

    Choi, Jong-Ho; Kuwata, Keith T.; Haas, Bernd-Michael; Cao, Yibin; Johnson, Matthew S.; Okumura, Mitchio

    1994-01-01

    Infrared spectra of mass‐selected clusters NO^+(H_2O)_n for n=1 to 5 were recorded from 2700 to 3800 cm^(−1) by vibrational predissociation spectroscopy. Vibrational frequencies and intensities were also calculated for n=1 and 2 at the second‐order Møller–Plesset (MP2) level, to aid in the interpretation of the spectra, and at the singles and doubles coupled cluster (CCSD) level energies of n=1 isomers were computed at the MP2 geometries. The smaller clusters (n=1 to 3) were complexes of H_2O...

  17. H2O2 INDUCES DELAYED HYPEREXCITABILITY IN NUCLEUS TRACTUS SOLITARII NEURONS

    Science.gov (United States)

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

    2014-01-01

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

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

    Science.gov (United States)

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

    2016-12-01

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

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

    Science.gov (United States)

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

    2017-05-15

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

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

    Science.gov (United States)

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

    2018-01-01

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

  1. Crystal structures of hydrates of simple inorganic salts. III. Water-rich aluminium halide hydrates: AlCl3 · 15H2O, AlBr3 · 15H2O, AlI3 · 15H2O, AlI3 · 17H2O and AlBr3 · 9H2O.

    Science.gov (United States)

    Schmidt, Horst; Hennings, Erik; Voigt, Wolfgang

    2014-09-01

    Water-rich aluminium halide hydrate structures are not known in the literature. The highest known water content per Al atom is nine for the perchlorate and fluoride. The nonahydrate of aluminium bromide, stable pentadecahydrates of aluminium chloride, bromide and iodide, and a metastable heptadecahydrate of the iodide have now been crystallized from low-temperature solutions. The structures of these hydrates were determined and are discussed in terms of the development of cation hydration spheres. The pentadecahydrate of the chloride and bromide are isostructural. In AlI(3) · 15H2O, half of the Al(3+) cations are surrounded by two complete hydration spheres, with six H2O in the primary and 12 in the secondary. For the heptadecahydrate of aluminium iodide, this hydration was found for every Al(3+).

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

    Science.gov (United States)

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

    2011-07-01

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

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

    Science.gov (United States)

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

    2011-07-01

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

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

    Science.gov (United States)

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

    2015-11-01

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

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

    Science.gov (United States)

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

    2017-05-09

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

  6. Adsorption of H2O and CO2 on supported amine sorbents

    NARCIS (Netherlands)

    Veneman, Rens; Frigka, Natalia; Zhao, Wenying; Li, Zhenshan; Kersten, Sascha R.A.; Brilman, Derk Willem Frederik

    2015-01-01

    In this work the adsorption of H2O and CO2 on Lewatit VP OC 1065 was studied in view of the potential application of this sorbent in post combustion CO2 capture. Both CO2 and H2O were found to adsorb on the amine active sites present on the pore surface of the sorbent material. However, where the

  7. Gas phase hydrogen peroxide production in atmospheric pressure glow discharges operating in He - H2O

    NARCIS (Netherlands)

    Vasko, C.A.; Veldhuizen, van E.M.; Bruggeman, P.J.

    2013-01-01

    The gas phase production of hydrogen peroxide (H2O2) in a RF atmospheric pressure glow discharge with helium and water vapour has been investigated as a function of the gas flow. It is shown that the production of H2O2 is through the recombination of two OH radicals in a three body collision and the

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

    DEFF Research Database (Denmark)

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

    2013-01-01

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

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

    DEFF Research Database (Denmark)

    2016-01-01

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

  10. Stability of globular proteins in H2O and D2O

    NARCIS (Netherlands)

    Efimova, Y. M.; Haemers, S.; Wierczinski, B.; Norde, W.; van Well, A. A.

    2007-01-01

    In several experimental techniques D2O rather then H2O is often used as a solvent for proteins. Concerning the influence of the solvent on the stability of the proteins, contradicting results have been reported in literature. In this paper the influence of H2O-D2O solvent substitution on the

  11. Stability of globular proteins in H2O and in D2O

    NARCIS (Netherlands)

    Efimova, Y.M.; Haemers, S.; Wierczinsky, B.; Norde, W.; Well, van A.A.

    2007-01-01

    In several experimental techniques D2O rather then H2O is often used as a solvent for proteins. Concerning the influence of the solvent on the stability of the proteins, contradicting results have been reported in literature. In this paper the influence of H2O-D2O solvent substitution on the

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

    Science.gov (United States)

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

    2016-03-01

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

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

    Science.gov (United States)

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

    2012-03-01

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

  14. Degradation of p-Nitrophenol by Lignin and Cellulose Chars: H2O2-Mediated Reaction and Direct Reaction with the Char.

    Science.gov (United States)

    Yang, Jing; Pignatello, Joseph J; Pan, Bo; Xing, Baoshan

    2017-08-15

    Chars and other black carbons are reactive toward certain compounds. Such reactivity has been attributed to reduction of O 2 by persistent free radicals in the solid to H 2 O 2 , which then back-reacts with the solid to generate reactive oxygen species (ROS; especially HO • ). We studied the decomposition of p-nitrophenol (PNP) by pure lignin and cellulose chars aged in moist air or a vacuum at room temperature for up to a month. In air, the chars chemisorbed oxygen, a portion of which was liberated as H 2 O 2 when the char was submerged in water. The evolved H 2 O 2 was simultaneously decomposed by the char. PNP reacted predominantly in the sorbed state and only reduction products (phenol, catechol) were identified. Aging the char in air sharply (within hours) reduced H 2 O 2 -producing capacity and free radical concentration, but more gradually reduced PNP decay rate over the month-long period. PNP decay was only modestly suppressed (12-30%) by H 2 O 2 removal (catalase), and had little effect on the free radical signal (reactive sites. Lignin char was generally more reactive than cellulose char. The Fe impurity in lignin played no role. The results are relevant to the fate of pollutants in black carbon-rich environments and the use of carbons in remediation.

  15. Raman Lidar Measurements During the International H2O Project. 2; Instrument Comparisons and Case Studies

    Science.gov (United States)

    Whiteman, D. N.; Demoz, B.; DiGirolamo, P.; Corner, J.; Veselovskii, I.; Evans, K.; Wang, Z.; Sabatino, D.; Schwemmer, G.; Gentry, B.

    2005-01-01

    The NASA/GSFC Scanning Raman Lidar (SRL) participated in the International H2O Project (IHOP) that occurred in May and June, 2002 in the midwestern part of the U. S. The SRL system configuration and methods of data analysis were described in part I of this paper. In this second part, comparisons of SRL water vapor measurements and those of chilled mirror radiosonde and LASE airborne water vapor lidar are performed. Two case studies are presented; one for daytime and one for nighttime. The daytime case study is of a convectively driven boundary layer event and is used to characterize the SRL water vapor random error characteristics. The nighttime case study is of a thunderstorm-generated cirrus cloud case that is studied in it s meteorological context. Upper tropospheric humidification due to precipitation from the cirrus cloud is quantified as is the cirrus cloud ice water content and particle depolarization ratio. These detailed cirrus cloud measurements are being used in a cirrus cloud modeling study.

  16. UV/H2O2 process performance improvement by ultrafiltration and physicochemical clarification systems for industrial effluent pretreatment

    Directory of Open Access Journals (Sweden)

    Ivanildo Hespanhol

    2012-12-01

    Full Text Available The present study evaluated the removal of TOC from an effluent with high organic load resulted from the treatment of oil-water emulsion by thermal process. Hollow Fiber Ultrafiltration membrane (HF-UF and physicochemical clarification process were used as pretreatment options to assess the influence of feed effluent quality on the UV/H2O2 oxidation process. Results for TOC removals showed HF-UF and physicochemical clarification processes can significantly improve the efficiency of UV/H2O2 oxidation process, when compared with the direct effluent oxidation. Reaction time for obtaining a TOC removal higher than 90% was reduced to approximately half of the time needed when no pretreatment was applied. Considering both pretreatment processes it was not possible to notice any significant difference on the UV/H2O2 oxidation process performance. However, the complexity of physicochemical process due to the use of three different chemicals and sludge production made the HF-UF process the best pretreatment alternative, without increasing the Total Dissolved Solids of the effluent, a very important issue when water reuse is considered.

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2011-07-01

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

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

    Institute of Scientific and Technical Information of China (English)

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

    2012-01-01

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

  19. Hydrogen constituents of the mesosphere inferred from positive ions - H2O, CH4, H2CO, H2O2, and HCN

    Science.gov (United States)

    Kopp, E.

    1990-01-01

    The concentrations in the mesosphere of H2O, CH4, H2CO, H2O2, and HCN were inferred from data on positive ion compositions, obtained from one mid-latitude and four high-latitude rocket flights. The inferred concentrations were found to agree only partially with the ground-based microwave measurements and/or model prediction by Garcia and Solomon (1985). The CH4 concentration was found to vary between 70 and 4 ppb in daytime and 900 and 100 ppbv at night, respectively. Unexpectedly high H2CO concentrations were obtained, with H2CO/H2O ratios between 0.0006 and 0.1, and a mean HCN volume mixing ratio of 6 x 10 to the -10th was inferred.

  20. Quasielastic neutron scattering and infra-red band contour study of H2O reorientations in [Ni(H2O)6] (ClO4)2

    International Nuclear Information System (INIS)

    Janik, J.A.; Janik, J.M.; Otnes, K.; Stanek, T.

    1980-01-01

    IR band contour measurements carried out for [Ni(H 2 O) 6 ] (ClO 4 ) 2 revealed an existence of fast H 2 O 180 deg flips around Ni-O axes at room temperatures. These flips were subjected to a more accurate study by the quasielastic neutron scattering method. Correlation times of the order of picosecond were obtained for room temperatures and the barrier to rotation of ca. 7 kcal/mole. The results are compared to those previously obtained for [Mg(H 2 O) 6 ] (ClO 4 ) 2 and also to those for [Ni(NH 3 ) 6 ] (ClO 4 ) 2 and [Mg(NH 3 ) 6 ] (ClO 4 ) 2 . (author)

  1. An open-framework three-dimensional indium oxalate: [In(OH)(C2O4)(H2O)]3.H2O

    International Nuclear Information System (INIS)

    Yang Sihai; Li Guobao; Tian Shujian; Liao Fuhui; Lin Jianhua

    2005-01-01

    By hydrothermal reaction of In 2 O 3 with H 2 C 2 O 4 .2H 2 O in the presence of H 3 BO 3 at 155 deg. C, an open-framework three-dimensional indium oxalate of formula [In(OH)(C 2 O 4 )(H 2 O)] 3 .H 2 O (1) has been obtained. The compound crystallizes in the trigonal system, space group R3c with a=18.668(3)A, c=7.953(2)A, V=2400.3(7)A 3 , Z=6, R 1 =0.0352 at 298K. The small pores in 1 are filled with water molecules. It loses its filled water at about 180 deg. C without the change of structure, then the bounded water at 260 deg. C, and completely decompounds at 324 deg. C. The residue is confirmed to be In 2 O 3

  2. [H2O ortho-para spin conversion in aqueous solutions as a quantum factor of Konovalov paradox].

    Science.gov (United States)

    Pershin, S M

    2014-01-01

    Recently academician Konovalov and co-workers observed an increase in electroconductivity and biological activity simultaneously with diffusion slowing (or nanoobject diameter increasing) and extremes of other parameters (ζ-potential, surface tension, pH, optical activity) in low concentration aqueous solutions. This phenomenon completely disappeared when samples were shielded against external electromagnetic fields by a Faraday cage. A conventional theory of water and water solutions couldn't explain "Konovalov paradox" observed in numerous experiments (representative sampling about 60 samples and 7 parameters). The new approach was suggested to describe the physics of water and explain "Konovalov paradox". The proposed concept takes into account the quantum differences of ortho-para spin isomers of H2O in bulk water (rotational spin-selectivity upon hydration and spontaneous formation of ice-like structures, quantum beats and spin conversion induced in the presence of a resonant electromagnetic radiation). A size-dependent self-assembly of amorphous complexes of H2O molecules more than 275 leading to the ice Ih structure observed in the previous experiments supports this concept.

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

    Science.gov (United States)

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

    2018-06-14

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

  4. A thermodynamic study of 1-propanol-glycerol-H2O at 25 degrees C: Effect of glycerol on molecular organization of H2O

    DEFF Research Database (Denmark)

    Parsons, M.T.; Westh, Peter; Davies, J.V.

    2001-01-01

    The excess chemical potential, partial molar enthalpy, and volume of 1-propanol were determined in ternary mixtures of 1-propanol-glycerol-H2O at 25degreesC. The mole fraction dependence of all these thermodynamic functions was used to elucidate the effect of glycerol on the molecular organization...... probability and, hence, the percolation nature of the hydrogen bond network is reduced. In addition, the degree of fluctuation inherent in liquid H2O is reduced by glycerol perhaps by participating in the hydrogen bond network via OH groups. At infinite dilution, the pair interaction coefficients in enthalpy...

  5. Study of thermal pressure and phase transitions in H2O using optical pressure sensors in the diamond anvil cell

    International Nuclear Information System (INIS)

    Sundberg, Sara; Lazor, Peter

    2004-01-01

    We present results of a study on the phase equilibria and pressure-volume-temperature relations for water and ice VII using an optical system designed for Raman spectroscopy and pressure-temperature measurements. The study shows that the strontium borate sensor represents an important tool for high-pressure-high-temperature manometry for temperatures below 600 K. In the pressure-temperature ranges 0-5 GPa and 240-600 K we detected phase transformations between four phases of H 2 O as documented by Raman spectra, pressure-temperature scans, and visual observations. Analysis of the interference fringes and comparison of the experimental data on thermal pressure with the published equations of state (EOSs) show that the heating/cooling cycles were carried out under quasi-isochoric conditions. The experimental results are discussed/analysed on the basis of different EOSs for water and ice

  6. Widespread distribution of OH/H2O on the lunar surface inferred from spectral data.

    Science.gov (United States)

    Bandfield, Joshua L; Poston, Michael J; Klima, Rachel L; Edwards, Christopher S

    2018-01-01

    Remote sensing data from lunar orbiters have revealed spectral features consistent with the presence of OH or H 2 O on the lunar surface. Analyses of data from the Moon Mineralogy Mapper spectrometer onboard the Chandryaan-1 spacecraft have suggested that OH/H 2 O is recycled on diurnal timescales and persists only at high latitudes. However, the spatial distribution and temporal variability of the OH/H 2 O, as well as its source, remain uncertain. Here we incorporate a physics-based thermal correction into analysis of reflectance spectra from the Moon Mineralogy Mapper and find that prominent absorption features consistent with OH/H 2 O can be present at all latitudes, local times, and surface types examined. This suggests the widespread presence of OH/H 2 O on the lunar surface without significant diurnal migration. We suggest that the spectra are consistent with the production of OH in space weathered materials by the solar wind implantation of H + and formation of OH at crystal defect sites, as opposed to H 2 O sourced from the lunar interior. Regardless of the specific composition or formation mechanism, we conclude that OH/H 2 O can be present on the Moon under thermal conditions more wide-ranging than previously recognized.

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

    Science.gov (United States)

    Xiang, Yulin; Xiang, Yuxiu; Wang, Lipeng

    2016-03-01

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

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

    Science.gov (United States)

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

    2013-01-01

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

  9. H2O2 modulates the energetic metabolism of the cloud microbiome

    Directory of Open Access Journals (Sweden)

    N. Wirgot

    2017-12-01

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

  10. H2O2 modulates the energetic metabolism of the cloud microbiome

    Science.gov (United States)

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

    2017-12-01

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

  11. Exploring H2O Prominence in Reflection Spectra of Cool Giant Planets

    Science.gov (United States)

    MacDonald, Ryan J.; Marley, Mark S.; Fortney, Jonathan J.; Lewis, Nikole K.

    2018-05-01

    The H2O abundance of a planetary atmosphere is a powerful indicator of formation conditions. Inferring H2O in the solar system giant planets is challenging, due to condensation depleting the upper atmosphere of water vapor. Substantially warmer hot Jupiter exoplanets readily allow detections of H2O via transmission spectroscopy, but such signatures are often diminished by the presence of clouds composed of other species. In contrast, highly scattering water clouds can brighten planets in reflected light, enhancing molecular signatures. Here, we present an extensive parameter space survey of the prominence of H2O absorption features in reflection spectra of cool (T eff clouds brighten the planet: T eff ∼ 150 K, g ≳ 20 ms‑2, f sed ≳ 3, m ≲ 10× solar. In contrast, planets with g ≲ 20 ms‑2 and T eff ≳ 180 K display substantially prominent H2O features embedded in the Rayleigh scattering slope from 0.4 to 0.73 μm over a wide parameter space. High f sed enhances H2O features around 0.94 μm, and enables these features to be detected at lower temperatures. High m results in dampened H2O absorption features, due to water vapor condensing to form bright, optically thick clouds that dominate the continuum. We verify these trends via self-consistent modeling of the low-gravity exoplanet HD 192310c, revealing that its reflection spectrum is expected to be dominated by H2O absorption from 0.4 to 0.73 μm for m ≲ 10× solar. Our results demonstrate that H2O is manifestly detectable in reflected light spectra of cool giant planets only marginally warmer than Jupiter, providing an avenue to directly constrain the C/O and O/H ratios of a hitherto unexplored population of exoplanetary atmospheres.

  12. A laboratory study of ikaite (CaCO3·6H2O) precipitation as a function of pH, salinity, temperature and phosphate concentration

    OpenAIRE

    Hu, Yu-Bin; Wolf-Gladrow, Dieter A.; Dieckmann, Gerhard S.; Völker, Christoph; Nehrke, Gernot

    2014-01-01

    Ikaite (CaCO3·6H2O) has only recently been discovered in sea ice, in a study that also provided first direct evidence of CaCO3 precipitation in sea ice. However, little is as yet known about the impact of physico-chemical processes on ikaite precipitation in sea ice. Our study focused on how the changes in pH, salinity, temperature and phosphate (PO4) concentration affect the precipitation of ikaite. Experiments were set up at pH from 8.5 to 10.0, salinities from 0 to 105 (in both artificial ...

  13. SORPTION OF ARSENATE AND ARSENITE ON RUO2 X H2O: ANALYSIS OF SORBED PHASE OXIDATION STATE BY XANES IN ADVANCED PHOTON SOURCE ACTIVITY REPORT 2002

    Science.gov (United States)

    The sorption reactions of arsenate (As(V)) and arsenite (As(III)) on RuO2 x H2O were examined by X-ray Absorption Near Edge Spectroscopy (XANES) to elucidate the solid state speciation of sorbed As. At all pH values studied (pH 4-8), RuO2 x H

  14. Thermochemical Kinetics of H2O and HNO3 on crystalline Nitric Acid Hydrates (alpha-, beta-NAT, NAD) in the range 175-200 K

    Science.gov (United States)

    Rossi, Michel J.; Iannarelli, Riccardo

    2015-04-01

    The growth of NAT (Nitric Acid Trihydrate, HNO3x3H2O) and NAD (Nitric Acid Dihydrate, HNO3x2H2O) on an ice substrate, the evaporative lifetime of NAT and NAD as well as the interconversion of alpha- and beta-NAT competing with evaporation and growth under UT/LS conditions depends on the interfacial kinetics of H2O and HNO3 vapor on the condensed phase. Despite the existence of some literature results we have embarked on a systematic investigation of the kinetics using a multidiagnostic experimental approach enabled by the simultaneous observation of both the gas (residual gas mass spectrometry) as well as the condensed phase (FTIR absorption in transmission). We report on thermochemically consistent mass accommodation coefficients alpha and absolute evaporation rates Rev/molecule s-1cm-3 as a function of temperature which yields the corresponding vapor pressures of both H2O and HNO3 in equilibrium with the crystalline phases, hence the term thermochemical kinetics. These results have been obtained using a stirred flow reactor (SFR) using a macroscopic pure ice film of 1 micron or so thickness as a starting substrate mimicking atmospheric ice particles and are reported in a phase diagram specifically addressing UT (Upper Troposphere)/LS (Lower Stratosphere) conditions as far as temperature and partial pressures are concerned. The experiments have been performed either at steady-state flow conditions or in transient supersaturation using a pulsed solenoid valve in order to generate gas pulses whose decay were subsequently monitored in real time. Special attention has been given to the effect of the stainless-steel vessel walls in that Langmuir adsorption isotherms for H2O and HNO3 have been used to correct for wall-adsorption of both probe gases. Typically, the accommodation coefficients of H2O and HNO3 are similar throughout the temperature range whereas the rates of evaporation Rev of H2O are significantly larger than for HNO3 thus leading to the difference in

  15. Redetermination of Ce[B5O8(OH(H2O]NO3·2H2O

    Directory of Open Access Journals (Sweden)

    Ya-Xi Huang

    2012-05-01

    Full Text Available The crystal structure of Ce[B5O8(OH(H2O]NO3·2H2O, cerium(III aquahydroxidooctaoxidopentaborate nitrate dihydrate, has been redetermined from single-crystal X-ray diffraction data. In contrast to the previous determination [Li et al. (2003. Chem. Mater. 15, 2253–2260], the present study reveals the location of all H atoms, slightly different fundamental building blocks (FBBs of the polyborate anions, more reasonable displacement ellipsoids for all non-H atoms, as well as a model without disorder of the nitrate anion. The crystal structure is built from corrugated polyborate layers parallel to (010. These layers, consisting of [B5O8(OH(H2O]2− anions as FBBs, stack along [010] and are linked by Ce3+ ions, which exhibit a distorted CeO10 coordination sphere. The layers are additionally stabilized via O—H...O hydrogen bonds between water molecules and nitrate anions, located at the interlayer space. The [BO3(H2O]-group shows a [3 + 1] coordination and is considerably distorted from a tetrahedral configuration. Bond-valence-sum calculation shows that the valence sum of boron is only 2.63 valence units (v.u. when the contribution of the water molecule (0.49 v.u. is neglected.

  16. Submillimeter H2O and H2O+emission in lensed ultra- and hyper-luminous infrared galaxies at z 2-4

    NARCIS (Netherlands)

    Yang, C.; Omont, A.; Beelen, A.; González-Alfonso, E.; Neri, R.; Gao, Y.; van der Werf, P.; Weiß, A.; Gavazzi, R.; Falstad, N.; Baker, A. J.; Bussmann, R. S.; Cooray, A.; Cox, P.; Dannerbauer, H.; Dye, S.; Guélin, M.; Ivison, R.; Krips, M.; Lehnert, M.; Michałowski, M. J.; Riechers, D. A.; Spaans, M.; Valiante, E.

    2016-01-01

    We report rest-frame submillimeter H2O emission line observations of 11 ultra- or hyper-luminous infrared galaxies (ULIRGs or HyLIRGs) at z 2-4 selected among the brightest lensed galaxies discovered in the Herschel-Astrophysical Terahertz Large Area Survey (H-ATLAS). Using the IRAM NOrthern

  17. Towards a Quantum Dynamical Study of the H_2O+H_2O Inelastic Collision: Representation of the Potential and Preliminary Results

    Science.gov (United States)

    Ndengue, Steve Alexandre; Dawes, Richard

    2017-06-01

    Water, an essential ingredient of life, is prevalent in space and various media. H_2O in the gas phase is the major polyatomic species in the interstellar medium (ISM) and a primary target of current studies of collisional dynamics. In recent years a number of theoretical and experimental studies have been devoted to H_2O-X (with X=He, H_2, D_2, Ar, ?) elastic and inelastic collisions in an effort to understand rotational distributions of H_2O in molecular clouds. Although those studies treated several abundant species, no quantum mechanical calculation has been reported to date for a nonlinear polyatomic collider. We present in this talk the preliminary steps toward this goal, using the H_2O molecule itself as our collider, the very accurate MB-Pol surface to describe the intermolecular interaction and the MultiConfiguration Time Dependent (MCTDH) algorithm to study the dynamics. One main challenge in this effort is the need to express the Potential Energy Surface (PES) in a sum-of-products form optimal for MCTDH calculations. We will describe how this was done and present preliminary results of state-to-state probabilities.

  18. Nd(BrO3)3-Yb(BrO3)3-H2O and Nd2(SeO4)3-Yb2(SeO4)3-H2O systems at 25 deg C

    International Nuclear Information System (INIS)

    Serebrennikov, V.V.; Batyreva, V.A.; Tsybukova, T.N.

    1981-01-01

    Using the methods of isothermal solubility the Nd(BrO 3 ) 3 - Yb(BrO 3 ) 3 -H 2 O and Nd 2 (SeO 4 ) 3 -Yb 2 (SeO 4 ) 3 -H 2 O systems are studied at 25 deg C. The compositions of the solid phases are determined by the method of ''residues''. The formation of two series of solid solutions in both systems is established. Besides, there is a crystallization region of Nd 2 (SeO 4 ) 3 in the system of selenates. The solubility diagrams of the systems are presented [ru

  19. TES/Aura L3 H2O Monthly Gridded V004

    Data.gov (United States)

    National Aeronautics and Space Administration — The TES Aura L3 H2O data consist of daily atmospheric temperature and VMR for the atmospheric species. Data are provided at 2 degree latitude X 4 degree longitude...

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

    Indian Academy of Sciences (India)

    Administrator

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

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

    Science.gov (United States)

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

    2013-10-01

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

  2. Dehydration of MoO 3 · 2H 2O: A Neutron Thermodiffractometry Study

    Science.gov (United States)

    Boudjada, N.; Rodríguez-Carvajal, J.; Anne, M.; Figlarz, M.

    1993-07-01

    A neutron powder thermodiffractometric study of the dehydration reactions MoO 3 · 2H 2O → MoO 3 · H 2O → MoO 3 has been carried out in order to investigate the topotactic mechanism previously reported. The topotactic character of the reactions is confirmed and an approximate model for the crystal structure of MoO 3 · H 2O is proposed. Quantitative data about the relative amount of the existing phases, as a function of temperature, have been deduced from multiphase profile analysis. The anomalous behavior of the cell parameters of MoO 3 · H 2O, at about 100°C, indicates the existence of a new phase transition. The evolution of the crystallite size of MoO 3 has also been obtained from the broadening of Bragg reflections at high temperature. The preferred direction of growth is along [021].

  3. Crystal structure of RbCe(SeO4)2 · 5H2O

    International Nuclear Information System (INIS)

    Ovanesyan, S.M.; Iskhakova, L.D.; Trunov, V.K.

    1987-01-01

    RbTR(SeO 4 ) 2 x5H 2 O TR=La-Pr are synthesized. Crystal structure of RbCe(SeO 4 ) 2 x5H 2 O is studied. Monoclinic unit parameters are: a=7,200(2), b=8,723(1), c=19,258(6) A, Β=90,88(2), ρ (calc) =3,304 sp.gr. P2 1 /c. Within the structure the Ce nine vertex cages are united by Se(1)- and Se(2)-tetrahedrons in (Ce(SeO 4 ) 2 (H 2 O) 5 ) 2 ∞ n- layers. Some crystal structure regularities of the laminated MTR(EO 4 ) 2 xnH 2 O (M=NH 4 ,K,Rb,Cs; TR=La-Ln, E=S,Se) are considered

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

    Data.gov (United States)

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

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

    Science.gov (United States)

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

    2018-05-14

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

  6. Transfer of π- from hydrogen to deuterium in H2O + D2O mixtures

    International Nuclear Information System (INIS)

    Stanislaus, S.; Measday, D.F.; Vetterli, D.; Weber, P.; Aniol, K.A.; Harston, M.R.; Armstrong, D.S.

    1989-07-01

    The transfer of stopping π - mesons from hydrogen to deuterium has been investigated in mixtures of H 2 O+D 2 O as a function of D 2 O concentration. The concentration dependence of the transfer probability is similar to that observed for the gas mixtures of H 2 and D 2 but slightly more transfer is found for H 2 O+D 2 O. (Author) 17 refs., 2 tabs., 4 figs

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

    Science.gov (United States)

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

    2017-12-22

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

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

    Science.gov (United States)

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

    2015-01-01

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

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

    African Journals Online (AJOL)

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

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

    Science.gov (United States)

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

    2017-06-06

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

  11. The rate constant for the CO + H2O2 reaction

    DEFF Research Database (Denmark)

    Glarborg, Peter; Marshall, Paul

    2009-01-01

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

  12. Viscosity of HI-I2-H2O solution at atmospheric pressure

    International Nuclear Information System (INIS)

    Chen, Songzhe; Zhang, Ping; Wang, Laijun; Xu, Jingming; Gao, Mengxue

    2014-01-01

    Iodine-Sulfur thermochemical cycle (IS-cycle) is one of the most promising massive hydrogen production methods. Basic properties data of the HI-I 2 -H 2 O solution involved in the HI decomposition section of IS-cycle are found to be very important. HI, I 2 , and H 2 O make up a highly non-ideal solution system. Viscosity and its variation with the composition/temperature are very essential for the flowsheet work and HI-H 2 O-I 2 solution’s fluid simulation, especially in the distillation and electro-electrodialysis processes. In this paper, viscosity values of HI-H 2 O-I 2 solutions were measured at atmospheric pressure and varying temperatures (from 20 to 125 ºC). As for the composition, the HI/H2O molar ratio of the samples ranged from 1:5.36 to 1:12.00, while the HI/I 2 molar ratio from 1.0 to 1.4.0. Both temperature and composition have dramatic influence on the viscosity. Increasing temperature or H 2 O/HI molar ratio will lead to the reduction of viscosity; while increasing of I 2 /HI molar ratio results in the increase of viscosity. It was also found that I 2 content has a larger and more complex influence on the viscosity of the HI-H 2 O-I 2 solution than H 2 O content does, especially at low temperature (<50 °C). (author)

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

    Science.gov (United States)

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

    2017-03-01

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

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

    Science.gov (United States)

    Saxena, Ina; Srikanth, Sandhya; Chen, Zhong

    2016-01-01

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

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

    DEFF Research Database (Denmark)

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

    2012-01-01

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

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

    Science.gov (United States)

    Liu, Kai; Zhang, Xuan; Yan, Kelu

    2018-05-15

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

  17. Photochemical degradation of diethyl phthalate with UV/H2O2

    International Nuclear Information System (INIS)

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

    2007-01-01

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

  18. Photochemistry of polycyclic aromatic hydrocarbons in cosmic water ice. II. Near UV/VIS spectroscopy and ionization rates

    Science.gov (United States)

    Bouwman, J.; Cuppen, H. M.; Steglich, M.; Allamandola, L. J.; Linnartz, H.

    2011-05-01

    Context. Mid-infrared emission features originating from polycyclic aromatic hydrocarbons (PAHs) are observed towards photon dominated regions in space. Towards dense clouds, however, these emission features are quenched. Observations of dense clouds show that many simple volatile molecules are frozen out on interstellar grains, forming thin layers of ice. Recently, observations have shown that more complex non-volatile species, presumably including PAHs, also freeze out and contribute to the ongoing solid-state chemistry. Aims: The study presented here aims at obtaining reaction rate data that characterize PAH photochemistry upon vacuum ultraviolet (VUV) irradiation in an interstellar H2O ice analogue to explore the potential impact of PAH:H2O ice reactions on overall interstellar ice chemistry. To this end, the experimental results are implemented in a chemical model under simple interstellar cloud conditions. Methods: Time-dependent near-UV/VIS spectroscopy on the VUV photochemistry of anthracene, pyrene, benzo[ghi]perylene and coronene containing interstellar H2O ice analogs is performed at 25 and 125 K, using an optical absorption setup. Results: Near-UV/VIS absorption spectra are presented for these four PAHs and their photoproducts including cationic species trapped in H2O ice. Oscillator strengths of the cation absorption bands are derived relative to the oscillator strength of the neutral parent PAH. The loss of the parent and growth of PAH photoproducts are measured as a function of VUV dose, yielding solid state reaction constants. The rate constants are used in an exploratory astrochemical model, to assess the importance of PAH:H2O ice photoprocessing in UV exposed interstellar environments, compared with the timescales in which PAH molecules are incorporated in interstellar ices. Conclusions: All four PAHs studied here are found to be readily ionized upon VUV photolysis when trapped in H2O ice and exhibit similar rates for ionization at astronomically

  19. Effects of H2O/Na2O molar ratio on the strength of alkaline activated ground blast furnace slag-ultrafine palm oil fuel ash based concrete

    International Nuclear Information System (INIS)

    Yusuf, Moruf Olalekan; Megat Johari, Megat Azmi; Ahmad, Zainal Arifin; Maslehuddin, Mohammed

    2014-01-01

    Highlights: • Effects of H 2 O/Na 2 O on GBFS-POFA alkaline activated concrete are investigated. • High H 2 O/Na 2 O contents enhance dissolutions/workability at the expense of strength. • Lower H 2 O/Na 2 O molar ratios aid compressive strength of the products. • Increase in H 2 O/Na 2 O favours the reactivity of Ca and the products molecular bonds. • Low H 2 O/Na 2 O positively affects the microstructural density of the products. - Abstract: Effects of H 2 O/Na 2 O molar ratios (MRs) on the developed alkaline activated pozzolanic solid wastes (PMs)-ultrafine palm oil fuel ash (UPOFA) and ground blast furnace slag (GBFS)-were studied by using the constant mass of combined activators (10 M NaOH aq + Na 2 SiO 3aq of silica-modulus (Ms = SiO 2 /Na 2 O) of 3.3).The free water content (FWC) expressed as FWC/(PMs) varied from 0.02 to 0.1 by mass while the total H 2 O/Na 2 O MRs ranged from 18.9 to 23.1 The findings revealed that increase in H 2 O/Na 2 O MRs negatively affects the strength but positively impact the mixture workability (consistency). The microstructural morphology examination using Scanning Electron Microscope coupled with Energy dispersive spectroscopy (SEM + EDS) reveals the contribution of H 2 O/Na 2 O MRs to the product nature, compactness, and the reactivity of Ca 2+ and Al 3+ while Fourier transform infra-red (FTIR) spectroscopy indicates that H 2 O/Na 2 O ratios contributed to the product amorphousity and carbonation process but sparingly affected its formed polymerized structural units (SiQ n (mAl), n = 2 and 3)

  20. Carbon-14 immobilization via the Ba(OH)2.8H2O process

    International Nuclear Information System (INIS)

    Haag, G.L.; Nehls, J.W. Jr.; Young, G.C.

    1983-03-01

    The airborne release of 4 C from varous nuclear facilities has been identified as a potential biohazard due to the long half-life of 14 C (5730 y) and the ease with which it may be assimilated into the biosphere. At ORNL, technology has been developed for the removal and immobilization of this radionuclide. Prior studies have indicated that 14 C will likely exist in the oxidized form as CO 2 and will contribute slightly to the bulk CO 2 concentration of the gas stream, which is airlike in nature (approx. 330 ppmv CO 2 ). The technology that has been developed utilizes the CO 2 -Ba(OH) 2 .8H 2 O gas-solid reaction with the mode of gas-solid contacting being a fixed bed. The product, BaCO 3 , possesses excellent thermal and chemical stability, prerequisites for the long-term disposal of nuclear wastes. For optimal process operation, studies have indicated that an operating window of adequate size does exist. When operating within the window, high CO 2 removal efficiency (effluent concentrations 99%), and an acceptable pressure drop across the bed (3 kPa/m at a superficial velocity of 13 cm/s) are possible. This paper addresses three areas of experimental investigation: (1) microscale studies on 150-mg samples to provide information concerning surface properties, kinetics, and equilibrium vapor pressures; (2) macroscale studies on large fixed beds (4.2 kg of reactant) to determine the effects of humidity, temperature, and gas flow rate upon bed pressure drop and CO 2 breakthrough; and (3) design, construction, and initial operation of a pilot unit capable of continuously processing a 34-m 3 /h (20-ft 3 /min) air-based gas stream

  1. Carbon-14 immobilization via the Ba(OH)28H2O process

    International Nuclear Information System (INIS)

    Haag, G.L.; Nehls, J.W. Jr.; Young, G.C.

    1982-01-01

    The airborne release of 14 C from various nuclear facilities has been identified as a potential biohazard due to the long half-life of 14 C (5730 yrs) and the ease in which it may be assimilated into the biosphere. At Oak Ridge National Laboratory, technology is under development, as part of the Airborne Waste Management Program, for the removal and immobilization of this radionuclide. Prior studies have indicated that the 14 C will likely exist in the oxidized form as CO 2 and will contribute slightly to the bulk CO 2 concentration of the gas stream, which is airlike in nature (approx. 330 ppMv CO 2 ). The technology under development utilizes the CO 2 - Ba(OH) 2 8H 2 O gas-solid reaction with the mode of gas-solid contacting being a fixed bed. The product, BaCO 3 , possessing excellent thermal and chemical stability, prerequisites for the long-term disposal of nuclear wastes. For optimal process operation, studies have indicated that an operating window of adequate size does exist. When operating within the window, high CO 2 removal efficiency (effluent concentrations 99%), and an acceptable pressure drop across the bed (3 kPa/m at 13 cm/s superficial velocity) are possible. This paper will address three areas of experimental investigation. These areas are (1) micro-scale studies on 150-mg samples to provide information concerning surface properties, kinetics, and equilibrium vapor pressures, (2) macro-scale studies on large fixed beds (4.2 kg reactant) to determine the effects of humidity, temperature, and gas flow-rate upon bed pressure drop and CO 2 breakthrough, and (3) the design, construction, and initial operation of a pilot unit capable of continuously processing a 34 m 3 /h (20 ft 3 /min) air-based gas stream

  2. H2-H2O-HI Hydrogen Separation in H2-H2O-HI Gaseous Mixture Using the Silica Membrane

    International Nuclear Information System (INIS)

    Pandiangan, Tumpal

    2002-01-01

    It was evaluated aiming at the application for hydrogen iodide decomposition in the thermochemical lS process. Porous alumina tube having pore size of 0.1 μm was modified by chemical vapor deposition using tetraethoxysilane. The permeance single gas of He, H 2 , and N 2 was measured at 300-600 o C. Hydrogen permeance of the modified membrane at a permeation temperature of 600 o C was about 5.22 x 10 -08 mol/Pa m 2 s, and 3.2 x 10 -09 of using gas mixture of H 2 -H 2 O-HI, where as HI permeances was below 1 x 10 -10 mol/Pa m 2 s. The Hydrogen permeance relative was not changed after 25 hours exposure in a mixture of H 2 -H 2 O-HI gas at the temperature of 450 o C. (author)

  3. Synthesis, structure, optical, photoluminescence and magnetic properties of K2[Co(C2O4)2(H2O)2]·4H2O

    Science.gov (United States)

    Narsimhulu, M.; Hussain, K. A.

    2018-06-01

    The synthesis, crystal structure, optical, photoluminescence and magnetic behaviour of potassium bis(oxalato)cobaltate(II)tertrahydrate{K2[Co(C2O4)2(H2O)2]·4H2O} are described. The compound was grown at room temperature from mixture of aqueous solutions by slow evaporation method. The X-ray crystallographic data showed that the compound belongs to the monoclinic crystal system with P21/n space group and Z = 4. The UV-visible diffuse absorbance spectra exhibited bands at 253, 285 and 541 nm in the visible and ultraviolet regions. The optical band gap of the compound was estimated as 3.4 eV. At room temperature, an intense photoluminescence was observed from this material around 392 nm when it excited at 254 nm. The variable temperature dc magnetic susceptibility measurements exposed paramagnetic behaviour at high temperatures and antiferromagnetic ordering at low temperatures.

  4. Theoretical study of [Li(H2O)n]+ and [K(H2O)n]+ (n = 1-4) complexes

    International Nuclear Information System (INIS)

    Wojcik, M.J.; Mains, G.J.; Devlin, J.P.

    1995-01-01

    The geometries, successive binding energies, vibrational frequencies, and infrared intensities are calculated for the [Li(H 2 O) n ] + and [K(H 2 O) n ] + (n = 1-4) complexes. The basis sets used are 6-31G * and LANL1DZ (Los Alamos ECP+DZ) at the SCF and MP2 levels. There is an agreement for calculated structures and frequencies between the MP2/6-31G * and MP2/LANL1DZ basis sets, which indicates that the latter can be used for calculations of water complexes with heavier ions. Our results are in a reasonable agreement with available experimental data and facilitate experimental study of these complexes. 19 refs., 4 figs., 6 tabs

  5. Magnetocaloric effect in gadolinium-oxalate framework Gd2(C2O4)3(H2O)6⋅(0⋅6H2O)

    International Nuclear Information System (INIS)

    Sibille, Romain; Didelot, Emilie; Mazet, Thomas; Malaman, Bernard; François, Michel

    2014-01-01

    Magnetic refrigerants incorporating Gd 3+ ions and light organic ligands offer a good balance between isolation of the magnetic centers and their density. We synthesized the framework material Gd 2 (C 2 O 4 ) 3 (H 2 O) 6 ⋅0.6H 2 O by a hydrothermal route and characterized its structure. The honeycomb lattice of Gd 3+ ions interlinked by oxalate ligands in the (a,c) plane ensures their decoupling in terms of magnetic exchange interactions. This is corroborated by magnetic measurements indicating negligible interactions between the Gd 3+ ions in this material. The magnetocaloric effect was evaluated from isothermal magnetization measurements. The maximum entropy change −ΔS M max reaches 75.9 mJ cm −3 K −1 (around 2 K) for a moderate field change (2 T)

  6. GaAs micromachining in the 1 H2SO4:1 H2O2:8 H2O system. From anisotropy to simulation

    Science.gov (United States)

    Tellier, C. R.

    2011-02-01

    The bulk micromachining on (010), (110) and (111)A GaAs substrates in the 1 H2SO4:1 H2O2:8 H2O system is investigated. Focus is placed on anisotropy of 3D etching shapes with a special emphasis on convex and concave undercuts which are of prime importance in the wet micromachining of mechanical structures. Etched structures exhibit curved contours and more and less rounded sidewalls showing that the anisotropy is of type 2. This anisotropy can be conveniently described by a kinematic and tensorial model. Hence, a database composed of dissolution constants is further determined from experiments. A self-elaborated simulator which works with the proposed database is used to derive theoretical 3D shapes. Simulated shapes agree well with observed shapes of microstructures. The successful simulations open up two important applications for MEMS: CAD of mask patterns and meshing of simulated shapes for FEM simulation tools.

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

    Science.gov (United States)

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

    2015-03-15

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

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

    International Nuclear Information System (INIS)

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

    1991-01-01

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

  9. Sources of superoxide/H2O2 during mitochondrial proline oxidation

    Directory of Open Access Journals (Sweden)

    Renata L.S. Goncalves

    2014-01-01

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

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

    Science.gov (United States)

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

    2012-07-01

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

  11. Monte Carlo analysis of Pu-H2O and UO2-PuO2-H2O critical assemblies with ENDF/B-IV data

    International Nuclear Information System (INIS)

    Hardy, J. Jr.; Ullo, J.J.

    1981-04-01

    A set of critical experiments, comprising thirteen homogeneous Pu-H 2 O assemblies and twelve UO 2 -PuO 2 lattices, was analyzed with ENDF/B-IV data and the RCPO1 Monte Carlo program, which modeled the experiments explicitly. Some major data sensitivities were also evaluated. For the Pu-H 2 O assemblies, calculated K/sub eff/ averaged 1.011. The large (2.7%) scatter of K/sub eff/ values for these assemblies was attributed mostly to uncertainties in physical specifications since no clear trends of K/sub eff/ were evident and data sensitivities were insignificant. The UO 2 -PuO 2 lattices showed just one trend of K/sub eff/, which indicated an overprediction of U238 capture consistent with that observed for uranium-H 2 O experiments. There was however a approx. 1% discrepancy in calculated K/sub eff/ between the two sets of UO 2 -PuO 2 lattices studied

  12. Immobilization of Alkali Metal Fluorides via Recrystallization in a Cationic Lamellar Material, [Th(MoO4)(H2O)4Cl]Cl·H2O.

    Science.gov (United States)

    Lin, Jian; Bao, Hongliang; Qie, Meiying; Silver, Mark A; Yue, Zenghui; Li, Xiaoyun; Zhu, Lin; Wang, Xiaomei; Zhang, Linjuan; Wang, Jian-Qiang

    2018-06-05

    Searching for cationic extended materials with a capacity for anion exchange resulted in a unique thorium molybdate chloride (TMC) with the formula of [Th(MoO 4 )(H 2 O) 4 Cl]Cl·H 2 O. The structure of TMC is composed of zigzagging cationic layers [Th(MoO 4 )(H 2 O) 4 Cl] + with Cl - as interlamellar charge-balancing anions. Instead of performing ion exchange, alkali thorium fluorides were formed after soaking TMC in AF (A = Na, K, and Cs) solutions. The mechanism of AF immobilization is elucidated by the combination of SEM-EDS, PXRD, FTIR, and EXAFS spectroscopy. It was observed that four water molecules coordinating with the Th 4+ center in TMC are vulnerable to competition with F - , due to the formation of more favorable Th-F bonds compared to Th-OH 2 . This leads to a single crystal-to-polycrystalline transformation via a pathway of recrystallization to form alkali thorium fluorides.

  13. On the Formation of Interstellar Water Ice: Constraints from a Search for Hydrogen Peroxide Ice in Molecular Clouds

    Science.gov (United States)

    Smith, R. G.; Charnely, S. B.; Pendleton, Y. J.; Wright, C. M.; Maldoni, M. M.; Robinson, G.

    2011-01-01

    Recent surface chemistry experiments have shown that the hydrogenation of molecular oxygen on interstellar dust grains is a plausible formation mechanism, via hydrogen peroxide (H2O2), for the production of water (H2O) ice mantles in the dense interstellar medium. Theoretical chemistry models also predict the formation of a significant abundance of H2O2 ice in grain mantles by this route. At their upper limits, the predicted and experimental abundances are sufficiently high that H2O2 should be detectable in molecular cloud ice spectra. To investigate this further, laboratory spectra have been obtained for H2O2/H2O ice films between 2.5 and 200 micron, from 10 to 180 K, containing 3%, 30%, and 97% H2O2 ice. Integrated absorbances for all the absorption features in low-temperature H2O2 ice have been derived from these spectra. For identifying H2O2 ice, the key results are the presence of unique features near 3.5, 7.0, and 11.3 micron. Comparing the laboratory spectra with the spectra of a group of 24 protostars and field stars, all of which have strong H2O ice absorption bands, no absorption features are found that can definitely be identified with H2O2 ice. In the absence of definite H2O2 features, the H2O2 abundance is constrained by its possible contribution to the weak absorption feature near 3.47 micron found on the long-wavelength wing of the 3 micron H2O ice band. This gives an average upper limit for H2O2, as a percentage of H2O, of 9% +/- 4%. This is a strong constraint on parameters for surface chemistry experiments and dense cloud chemistry models.

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

    Science.gov (United States)

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

    2015-01-01

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

  15. U3Si2 behavior in H2O environments: Part II, pressurized water with controlled redox chemistry

    Science.gov (United States)

    Nelson, A. T.; Migdisov, A.; Wood, E. Sooby; Grote, C. J.

    2018-03-01

    Recent interest in U3Si2 as an advanced light water reactor fuel has driven assessment of numerous properties, but characterization of its response to H2O environments is sparse in available literature. The behavior of U3Si2 in H2O containing atmospheres is investigated and presented in a two-part series of articles. This work examines the behavior of U3Si2 following exposure to pressurized H2O at temperatures from 300 to 350 °C. Testing was performed using two autoclave configurations and multiple redox conditions. Use of solid state buffers to attain a controlled water chemistry is also presented as a means to test actinide-bearing systems. Buffers were used to vary the hydrogen concentration between 1 and 30 parts per million H2. Testing included UN, U3Si5, and UO2. Both UN and U3Si5 were found to rapidly pulverize in less than 50 h at 300 °C. Uranium dioxide was included as a control for the autoclave system, and was found to be minimally impacted by exposure to pressurized water at the conditions tested for extended time periods. Testing of U3Si2 at 300 °C found reasonable stability through 30 days in 1-5 ppm H2. However, pulverization was observed following 35 days. The redox condition of testing strongly affected pulverization. Characterization of the resulting microstructures suggests that the mechanism responsible for pulverization under more strongly reducing conditions differs from that previously identified. Hydride formation is hypothesized to drive this transition. Testing performed at 350 °C resulted in rapid pulverization of U3Si2 in under 50 h.

  16. Using mineral equilibria to estimate H2O activities in peridotites from the Western Gneiss Region of Norway

    NARCIS (Netherlands)

    Kang, Patricia; Lamb, William M.; Drury, Martyn

    2017-01-01

    The Earth's mantle is an important reservoir of H2O, and even a small amount of H2O has a significant influence on the physical properties of mantle rocks. Estimating the amount of H2O in rocks from the Earth's mantle would, therefore, provide some insights into the physical properties of this

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

    NARCIS (Netherlands)

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

    2009-01-01

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

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

    Science.gov (United States)

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

    2016-01-01

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

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

    Science.gov (United States)

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

    2017-01-01

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

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

    Science.gov (United States)

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

    2013-05-23

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

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

    International Nuclear Information System (INIS)

    Holmboe, Michael; Jonsson, Mats; Wold, Susanna

    2012-01-01

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

  2. H2-O2 fuel cell and advanced battery power systems for autonomous underwater vehicles: performance envelope comparisons

    International Nuclear Information System (INIS)

    Schubak, G.E.; Scott, D.S.

    1993-01-01

    Autonomous underwater vehicles have traditionally been powered by low energy density lead-acid batteries. Recently, advanced battery technologies and H 2 -O 2 fuel cells have become available, offering significant improvements in performance. This paper compares the solid polymer fuel cell to the lithium-thionyl chloride primary battery, sodium-sulfur battery, and lead acid battery for a variety of missions. The power system performance is simulated using computer modelling techniques. Performance envelopes are constructed, indicating domains of preference for competing power system technologies. For most mission scenarios, the solid polymer fuel cell using liquid reactant storage is the preferred system. Nevertheless, the advanced battery systems are competitive with the fuel cell systems using gaseous hydrogen storage, and they illustrate preferred performance for missions requiring high power density. 11 figs., 4 tabs., 15 refs

  3. H2SO4-HNO3-H2O ternary system in the stratosphere

    Science.gov (United States)

    Kiang, C. S.; Hamill, P.

    1974-01-01

    Estimation of the equilibrium vapor pressure over the ternary system H2SO4-HNO3-H2O to study the possibility of stratospheric aerosol formation involving HNO3. It is shown that the vapor pressures for the ternary system H2SO4-HNO3-H2O with weight composition around 70-80% H2SO4, 10-20% HNO3, 10-20% H2O at -50 C are below the order of 10 to the minus 8th mm Hg. It is concluded that there exists more than sufficient nitric acid and water vapor in the stratosphere to participate in ternary system aerosol formation at -50 C. Therefore, HNO3 should be present in stratospheric aerosols, provided that H2SO4 is also present.

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

    Science.gov (United States)

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

    2015-02-26

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

  5. Investigating the adsorption of H2O on ZnO nanoclusters by first principle calculations

    KAUST Repository

    Al-Sunaidi, Abdullah A.

    2011-04-01

    The interaction of a single H2O molecule on selected ZnO nanoclusters is investigated by carrying out calculations based on the density-functional theory at the hybrid-GGA (B97-2) level. These clusters have ring, drum, tube and bubble shapes and their physical properties like the binding energy and the band gap energy depend strongly on the shape and size of the cluster. Depending on the stability of the cluster, H2O show both chemisorption and dissociation on the surfaces of the clusters. We analyzed the effect of H2O adsorption on the properties of clusters of size n = 12 via the density of state, HOMO-LUMO orbitals and the changes in the IR frequencies. © 2011 Elsevier B.V. All rights reserved.

  6. Influence of H2O2 on LPG fuel performance evaluation

    International Nuclear Information System (INIS)

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

    2014-01-01

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

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

    DEFF Research Database (Denmark)

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

    1999-01-01

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

  8. Mechanism of H2O-Induced Conductance Changes in AuCl4-Functionalized CNTs

    KAUST Repository

    Murat, Altynbek

    2015-04-30

    We employ ab initio self-interaction corrected density functional theory combined with the nonequilibrium Green\\'s function method to study the electronic and quantum transport properties of carbon nanotubes (CNTs) functionalized with AuCl4 molecules. In particular, we investigate the electronic structure and characterize the conductance for different concentrations and configurations of randomly distributed AuCl4 molecules with and without the adsorption of H2O. We thus propose a mechanism that explains the origin of the recently observed resistivity changes of AuCl4-functionalized CNTs upon H2O adsorption. We find that water adsorption shifts the highest occupied Cl and Au states down in energy and thereby reduces the scattering of the electrons around the Fermi energy, hence enhancing the conductivity. Our results help in the development of highly sensitive nanoscale H2O vapor sensors based on AuCl4-functionalized CNTs. © 2015 American Chemical Society.

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

    International Nuclear Information System (INIS)

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

    1988-01-01

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

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

    DEFF Research Database (Denmark)

    Zhang, Yifeng; Angelidaki, Irini

    2016-01-01

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

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

    Directory of Open Access Journals (Sweden)

    Sai Wang Seto

    2017-01-01

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

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

    Science.gov (United States)

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

    2017-03-01

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

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

    Science.gov (United States)

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

    2018-02-01

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

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

    International Nuclear Information System (INIS)

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

    2011-01-01

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

  15. Phosphorus recovery from biogas slurry by ultrasound/H2O2 digestion coupled with HFO/biochar adsorption process.

    Science.gov (United States)

    He, Xuemeng; Zhang, Tao; Ren, Hongqiang; Li, Guoxue; Ding, Lili; Pawlowski, Lucjan

    2017-02-01

    Phosphorus (P) recovery from biogas slurry has recently attracted considerable interest. In this work, ultrasound/H 2 O 2 digestion coupled with ferric oxide hydrate/biochar (HFO/biochar) adsorption process was performed to promote P dissolution, release, and recovery from biogas slurry. The results showed that the optimal total phosphorus release efficiency was achieved at an inorganic phosphorus/total phosphorus ratio of 95.0% at pH 4, 1mL of added H 2 O 2 , and ultrasonication for 30min. The P adsorption by the HFO/biochar followed pseudo second-order kinetics and was mainly controlled by chemical processes. The Langmuir-Freundlich model matched the experimental data best for P adsorption by HFO/biochar at 298 and 308K, whereas the Freundlich model matched best at 318K. The maximum amount of P adsorbed was 220mg/g. The process was endothermic, spontaneous, and showed an increase in disorder at the solid-liquid interface. The saturated adsorbed HFO/biochar continually releases P and is most suitable for use in an alkaline environment. The amount of P released reached 29.1mg/g after five extractions. P mass balance calculation revealed that 11.3% of the total P can be made available. Copyright © 2016. Published by Elsevier Ltd.

  16. The influence of H2O line blanketing on the spectra of cool dwarf stars

    Science.gov (United States)

    Allard, F.; Hauschildt, P. H.; Miller, S.; Tennyson, J.

    1994-01-01

    We present our initial results of model atmosphere calculations for cool M dwarfs using an opacity sampling method and a new list of H2O lines. We obtain significantly improved fits to the infrared spectrum of the M dwarf VB10 when compared to earlier models. H2O is by far the dominant opacity source in cool stars. To illustrate this, we show the Rosseland mean of the total extinction under various assumptions. Our calculations demonstrate the importance of a good treatment of the water opacities in cool stars and the improvements possible by using up-to-date data for the water line absorption.

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

    OpenAIRE

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

    2015-01-01

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

  18. Mechanism and kinetics of LiX(X=H, D, T) + H2O reaction

    International Nuclear Information System (INIS)

    Lei Hongjie; Duan Hao; Xing Pifeng; Tang Yongjian

    2011-01-01

    The reaction mechanism of LiX(X=H, D, T) with H 2 O was investigated at MP2/6-311G (d) level using ab initio quantum chemistry in Gaussian 03 software. The equilibrium geometries, harmonic frequencies and energy of various stationary points on the potential energy surfaces were calculated in the lowest singlet states. Considering the quantum correction, the reaction rate constants were calculated using classical transition state theory. The results show the reaction of LiH (LiD, LiT) with H 2 O was considerably dependent on temperature that it is lower, the reaction rate constants are smaller. (authors)

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

    Science.gov (United States)

    Pomari, Elena; Stefanon, Bruno; Colitti, Monica

    2014-01-01

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

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

    Directory of Open Access Journals (Sweden)

    Pomari E

    2014-06-01

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

  1. On the Electronic Structure of [Cu(H2O)6]2+

    DEFF Research Database (Denmark)

    Tanaka, Kiyoshi; Johansen, Helge

    1997-01-01

    The electronic structure of the ground state and doublet excited states due to d-d transitions and charge transfer transitions from ligand to copper of [Cu(H2O)6]2+ are investigated by ab initio calculations. The excited states corresponding to the the d-d transitions are calculated to be 1.1 - 1...... on the description of these excited states. The chargetransfer excitations are predicted to start around 6.5 eV for [Cu(H2O)6]2+....

  2. Ammonia removal from leachate by photochemical process using H2O2

    Directory of Open Access Journals (Sweden)

    Giovani Archanjo Brota

    2010-08-01

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

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

    Directory of Open Access Journals (Sweden)

    Yuxin Jia et al

    2007-01-01

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

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

    International Nuclear Information System (INIS)

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

    2017-01-01

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

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

    Science.gov (United States)

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

    2018-02-09

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

  6. Solubility of apatite in H2O-NaCl and silicate-bearing solutions at 0.7-3.0 GPa, 800° C

    Science.gov (United States)

    Antignano, A.; Manning, C. E.

    2004-12-01

    Apatite is a major reservoir for the rare-earth elements (REE) in the earth's crust. However, little is known about its solubility in metamorphic fluids. We measured the solubility of apatite in H2O-NaCl and silicate bearing fluids at 800° C and 1.0-2.0 GPa using a piston-cylinder apparatus with NaCl-graphite furnaces. A single Durango fluor-apatite crystal was loaded into a 1.6 mm OD Pt inner capsule, which was crimped and then placed in a 3.5 OD Pt outer capsule with ultra pure H2O and NaCl or powdered albite. Solubility was determined by the weight loss of the apatite grain after 24 hrs. In the H2O-NaCl experiments, total dissolved solids (TDS) were initially below detection (0.4 millimolal) between XNaCl= 0 and XNaCl= 0.025. At XNaCl= 0.035, solubility was 3.3(0.2) millimolal (errors are 1s), and it increased to 57.5(0.4) millimolal at XNaCl= 0.526. Our results show that there is an enhancement in apatite solubility with increasing pressure in pure H2O. Solubility is initially below detection at bearing solutions. This probably explains textures in which monazite mantles apatite, which are common in granulite metamorphic terranes, such as the Kiirunavaara magnetite-apatite ore.

  7. The rates and mechanisms of water exchange of actinide aqua ions: A variable temperature 17O NMR study of U(H2O)104+, UF(H2O)93+, and Th(H2O)104+

    International Nuclear Information System (INIS)

    Farkas, I.; Grenthe, I.; Banyai, I.

    2000-01-01

    The rate constants and the activation parameters for the exchange between water solvent and [U(H 2 O) 10 ] 4+ and [UF(H 2 O) 9 ] 3+ , and a lower limit for the rate constant at room temperature for [Th(H 2 O) 10 ] 4+ , were determined by 17 O NMR spectroscopy in the temperature range 255--305 K. The experiments were made at different constant hydrogen ion concentrations, which varied between 0.16 and 0.8 mol kg -1 . The Th(IV) system was investigated using Tb 3+ as a shift reagent. The following kinetic parameters at 25 C were obtained: k ex = (5.4 ± 0.6) 10 6 x -1 , ΔH double dagger = 34 ± 3 kJ mol -1 , ΔS ++ = -16 ± 10 J mol -1 K -1 for U 4+ (aq), k ex = (5.5 ± 0.7) 10 6 x -1 , ΔH d ouble dagger = 34 ± 3 kJ mol -1 , ΔS ++ = 3 ± 15 J mol -1 K -1 for UF 3+ (Iaq), and k ex > 5 10 7 s -1 for Th 4+ (aq), where the uncertainty is given at the 2σ-level. This is the first experimental information on the kinetic parameters for the exchange of water for any M 4+ ion. There is no information on the rates and mechanisms of ligand substitutions involving other mono-dentate ligands, hence the mechanistic interpretation of the data is by necessity provisional. The kinetic data and the known ground-state geometry with a coordination number of 10 ± 1 for the Th(IV) and U(IV) complexes suggest a dissociatively activated interchange mechanism. There is no noticeable effect of coordination of one fluoride or one hydroxide to U(IV) on the water exchange rate. This is unusual, for other metal ions there is a strong labilizing of coordinated water when a second ligand is bonded, e.g., in complexes of aluminum and some d-transition elements. In previous studies of the rates and mechanisms of ligand exchange in uranium (VI) systems the authors found a strong decrease in the lability of coordinated water in some fluoride containing complexes

  8. Vapor pressure and specific electrical conductivity in the solid and molten H2O-CsH2PO4-CsPO3 system—a novel electrolyte for water electrolysis at ~ 225–400 °C

    DEFF Research Database (Denmark)

    Nikiforov, Aleksey Valerievich; Berg, Rolf W.; Bjerrum, Niels J.

    2018-01-01

    Cesium dihydrogen phosphate, CsH2PO4 (CDP) was studied for water electrolysis at ~ 225–400 °C. In the presence of sufficient humidity, CDP is structurally disordered and super-protonic conducting with conductivities reaching 0.2–0.25 S cm−1, when determined in suitable H-shaped sealed conductivity...... on internal reference gases. Pressures up to ~ 49 bar were estimated, much higher than previously expected. Conductivities were given as polynomials and plotted in solid and liquid states. Water splitting electrolysis 2H2O → 2H2 + O2 was demonstrated by Raman at ~ 355 °C under a water pressure of ~ 23 bar...... in a quartz cell with platinum electrodes, showing molten CDP to have significant potential for water electrolysis....

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

    Science.gov (United States)

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

    2014-10-01

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

  10. Reactions of electronically excited molecular nitrogen with H2 and H2O molecules: theoretical study

    Science.gov (United States)

    Pelevkin, Alexey V.; Sharipov, Alexander S.

    2018-05-01

    Comprehensive quantum chemical analysis with the usage of the second-order perturbation multireference XMCQDPT2 approach was carried out to study the processes in the   +  H2 and   +  H2O systems. The energetically favorable reaction pathways have been revealed based on the exploration of potential energy surfaces. It has been shown that the reactions   +  H2 and   +  H2O occur with small activation barriers and, primarily, lead to the formation of N2H  +  H and N2H  +  OH products, respectively. Further, the interaction of these species could give rise to the ground state and H2 (or H2O) products, however, the estimations, based on RRKM theory and dynamic reaction coordinate calculations, exhibited that the   +  H2 and   +  H2O reactions lead to the dissociative quenching predominately. Appropriate rate constants for revealed reaction channels have been estimated by using a canonical variational theory and capture approximation. Corresponding three-parameter Arrhenius expressions for the temperature range T  =  300  ‑  3000 K were reported.

  11. Relative transport of water (H2O) and tritiated water (HTO) across cellulose acetate (CA) membranes

    International Nuclear Information System (INIS)

    Prabhakar, S.; Misra, B.M.; Ramani, M.P.S.

    1986-01-01

    The relative transport characteristics of water (H 2 O) and tritiated water (HTO) were evaluated through cellulose acetate membranes under osmosis, reverse osmosis and pervaporation. The results indicate that the relative transport is independent of the process. The anamolous observations under osmotic conditions are explained. (orig.)

  12. The structure of mixed H2O-OH monolayer films on Ru(0001)

    DEFF Research Database (Denmark)

    Tatarkhanov, M.; Fomin, E.; Salmeron, M.

    2008-01-01

    temperature molecular phase can also be converted to a mixed H2O-OH phase through excitation by the tunneling electrons when their energy is 0.5 eV or higher above the Fermi level. Structural models based on the STM images were used for density functional theory optimizations of the stripe geometry...

  13. Acceleration of protons to above 6 MeV using H2O 'snow' nanowire targets

    International Nuclear Information System (INIS)

    Pomerantz, I.; Schleifer, E.; Nahum, E.; Eisenmann, S.; Botton, M.; Gordon, D.; Sprangel, P.; Zigler, A.

    2012-01-01

    A scheme is presented for using H 2 O 'snow' nanowire targets for the generation of fast protons. This novel method may relax the requirements for very high laser intensities, thus reducing the size and cost of laser based ion acceleration system.

  14. The H2O/D2O exchange across vesicular lipid bilayers

    International Nuclear Information System (INIS)

    Engelbert, H.P.; Lawaczek, R.

    1985-01-01

    A new method to measure the water (D 2 O/H 2 O) permeation across vesicular lipid bilayers is described. The method is based on the solvent isotope effect of the light scattering which is a consequence of the different indices of refraction of D 2 O and H 2 O. Unilamellar lipid vesicles in excess of H 2 O are rapidly mixed with D 2 O or vice versa. As result of the H 2 O/D 2 O exchange across the vesicular bilayer the light scattering signal has a time dependent, almost single exponential component allowing the deduction of the exchange relaxation rate and, at known size, of the permeability coefficient. The experimental results are in accord with calculations from the Mie theory of light scattering for coated spheres. The method is applicable for large vesicles where the permeation is the rate-limiting step. Size separations are performed by a flow dialysis through a sequence of pore-membrane-filters. For dimyristoyl-lecithin bilayers the water permeability-coefficient is 1.9 . 10 -5 cm/s in the crystalline phase and increases by a factor of 10-100 in the liquid-crystalline state. The temperature dependence of the permeation exhibits a sharp change at the phase transition. For binary mixtures of lecithins this sharp change follows the solidus curve of the non-ideal phase diagram determined by spectroscopic techniques. (orig.)

  15. Validation of UARS Microwave Limb Sounder 183 GHz H2O Measurements

    Science.gov (United States)

    Lahoz, W. A.; Suttie, M. R.; Froidevaux, L.; Harwood, R. S.; Lau, C. L.; Lungu, T. A.; Peckham, G. E.; Pumphrey, H. C.; Read, W. G.; Shippony, Z.; hide

    1996-01-01

    The Upper Atmosphere Research Satellite (UARS) microwave limb sounder (MLS) makes measurements of thermal emission at 183.3 GHz which are used to infer the concentration of water vapor over a pressure range of 46-0.2hPa (approximately 20-60 km). We provide a validation of MLS H2O by analyzing the integrity of the measurements, by providing an error characterization, and by comparison with data from other instruments. It is estimated that version 3 MLS H2O retrievals are accurate to within 20-25% in the lower stratosphere and to within 8-13% in the upper stratosphere and lower mesosphere. The precision of a single profile is estimated to be approximately 0.15 parts per million by volume (ppmv) in the midstratosphere and 0.2 ppmv in the lower and upper stratosphere. In the lower mesosphere the estimate of a single profile precision is 0.25-0.45 ppmv. During polar winter conditions, H2O retrievals at 46 hPa can have a substantial contribution from climatology. The vertical resolution of MLS H2O retrievals is approximately 5 km.

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

    NARCIS (Netherlands)

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

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

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

    African Journals Online (AJOL)

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

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

    Science.gov (United States)

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

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

    Directory of Open Access Journals (Sweden)

    Hamid R Molavian

    2016-08-01

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

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

    Directory of Open Access Journals (Sweden)

    Rubio-Clemente Ainhoa

    2017-01-01

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

  1. Enhanced H2O formation through dust grain chemistry in X-ray exposed environments

    NARCIS (Netherlands)

    Meijerink, R.; Cazaux, S.; Spaans, M.

    Context. The ultraluminous infrared galaxy Mrk 231, which shows signs of both black hole accretion and star formation, exhibits very strong water rotational lines between lambda = 200-670 mu m, comparable to the strength of the CO rotational lines. High-redshift quasars also show similar CO and H2O

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

    Directory of Open Access Journals (Sweden)

    M.R. Samarghandi

    2014-01-01

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

  3. The abundance and emission of H2O and O-2 in clumpy molecular clouds

    NARCIS (Netherlands)

    Spaans, M; van Dishoeck, EF

    2001-01-01

    Recent observations with the Submillimeter Wave Astronomy Satellite (SWAS) indicate abundances of gaseous H2O and O-2 in dense molecular clouds that are significantly lower than those found in standard homogeneous chemistry models. We present here results for the thermal and chemical balance of

  4. Mechanisms in manganese catalysed oxidation of alkenes with H2O2

    NARCIS (Netherlands)

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

    2013-01-01

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

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

    African Journals Online (AJOL)

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

  6. Nanosecond pulsed discharges in N2 and N2/H2O mixtures

    NARCIS (Netherlands)

    Joosten, R.M.; Verreycken, T.; Veldhuizen, van E.M.; Bruggeman, P.J.

    2011-01-01

    Nanosecond pulsed discharges in N2 and N2/H2O at atmospheric pressure between two pin-shaped electrodes are studied. The evolution of the discharge is investigated with time-resolved imaging and optical emission spectroscopy. The discharge consists of three phases, the ignition (mainly molecular

  7. Dense Molecular Gas and H2O Maser Emission in Galaxies F ...

    Indian Academy of Sciences (India)

    2School of Physics and Telecommunication Engineering, South China Normal University,. Guangzhou 510006, China. ∗ e-mail: jszhang@gzhu.edu.cn. Abstract. Extragalactic H2O masers have been found in dense gas cir- cumstance in off-nuclear star formation regions or within parsecs of. Active Galactic Nuclei (AGNs).

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

    Science.gov (United States)

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

    2015-04-01

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

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

    KAUST Repository

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

    2014-01-01

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

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

    Science.gov (United States)

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

    2015-09-09

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

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

    NARCIS (Netherlands)

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

    2010-01-01

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

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

    International Nuclear Information System (INIS)

    Midorikawa, Kaoru; Murata, Mariko; Kawanishi, Shosuke

    2005-01-01

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

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

    International Nuclear Information System (INIS)

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

    2014-01-01

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

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

    Indian Academy of Sciences (India)

    Unknown

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

  15. Relaxation phenomena in CsCoCl3·2 H2O

    NARCIS (Netherlands)

    Flokstra, Jakob; Gerritsma, G.J.; Vermeulen, A.J.W.A; Botterman, A.C.

    1973-01-01

    Dynamic susceptibility measurements have been performed on a single crystal of CsCoCl3·2H2O at liquid temperatures by means of a Hartshorn mutual inductance bridge. At the magnetic phase transition a maximum in τabs(H) has been observed. A jump in τabs(T) has been found at the λ-point of liquid

  16. High purity H2/H2O/Ni/SZ electrodes at 500º C

    DEFF Research Database (Denmark)

    Høgh, Jens Valdemar Thorvald; Hansen, Karin Vels; Norrman, Kion

    2013-01-01

    of stabilized zirconia (SZ) with 10, 13 and 18 mol% yttria and one with 6 mol% scandia plus 4 mol% yttria were studied at open circuit voltage at 400-500 C in mixtures of H2/H2O over 46 days. The polarization resistances (Rp) for all samples increased significantly during the first 10-20 days at 500 C...

  17. Investigating the adsorption of H2O on ZnO nanoclusters by first principle calculations

    KAUST Repository

    Al-Sunaidi, Abdullah A.; Goumri-Said, Souraya

    2011-01-01

    and their physical properties like the binding energy and the band gap energy depend strongly on the shape and size of the cluster. Depending on the stability of the cluster, H2O show both chemisorption and dissociation on the surfaces of the clusters. We analyzed

  18. Electron capture in collisions between O6+ ions and H2O molecules

    NARCIS (Netherlands)

    Bodewits, D.; Hoekstra, R.

    By means of photon emission spectroscopy, state selective electron capture cross section for low energy (0.1-7.5 keV/amu) collisions of O6+ on H2O molecules have been measured. Over the range of interaction energies the state selective cross sections change strongly, i.e., by factors up to 5, while

  19. Thermally activated 3D to 2D structural transformation of [Ni2(en)2(H2O)6(pyr)]·4H2O flexible coordination polymer

    International Nuclear Information System (INIS)

    Begović, Nebojša N.; Blagojević, Vladimir A.; Ostojić, Sanja B.; Radulović, Aleksandra M.; Poleti, Dejan; Minić, Dragica M.

    2015-01-01

    Thermally activated 3D to 2D structural transformation of the binuclear [Ni 2 (en) 2 (H 2 O) 6 (pyr)]·4H 2 O complex was investigated using a combination of theoretical and experimental methods. Step-wise thermal degradation (dehydration followed by release of ethylene diamine) results in two layered flexible coordination polymer structures. Dehydration process around 365 K results in a conjugated 2D structure with weak interlayer connectivity. It was shown to be a reversible 3D to 2D framework transformation by a guest molecule, and rehydration of the dehydration product occurs at room temperature in saturated water vapor. Rehydrated complex exhibits lower dehydration temperature, due to decreased average crystalline size, with higher surface area resulting in easier release and diffusion of water during dehydration. Thermal degradation of dehydration around 570 K, results in loss of ethylene diamine, producing a related 2D layered polymer structure, without interconnectivity between individual polymer layers. - Highlights: • Reversible 3D to 2D framework topochemical transformation on dehydration around 365 K. • Resulting polymer exhibits 2D layered structure with weak interlayer connectivity. • Dehydration is fully reversible in saturated water vapor at room temperature. • Further degradation around 570 K yields 2D polymer without interlayer connectivity. • 2D polymer exhibits conjugated electronic system

  20. Synthesis, crystal structure and thermal decomposition mechanism of the complex [Sm(p-BrBA)3bipy.H2O]2.H2O

    International Nuclear Information System (INIS)

    Zhang Haiyan; Zhang Jianjun; Ren Ning; Xu Suling; Tian Liang; Bai Jihai

    2008-01-01

    A new binuclear samarium (III) complex [Sm(p-BrBA) 3 bipy.H 2 O] 2 .H 2 O (p-BrBA = p-bromobenzoic acid; bipy = 2,2'-bipyridine) has been synthesized and characterized by elemental analysis, UV, IR, molar conductance and TG-DTG techniques. The structure of the complex was established by single crystal X-ray diffraction. It crystallizes in triclinic, space group P1-bar with a = 8.2476(7) A, b = 13.3483(10) A, c = 15.9035(13) A, α 73.9160(10) o , β = 78.9630(10) o , γ = 74.4770(10) o , Z = 1, D c 1.947 g cm -3 , F(000) = 910. The carboxylic groups are bonded to the samarium ion in two modes: bidentate bridging, monodentate. Each center Sm 3+ ion is eight-coordinated by one 2,2'-bipyridine molecular, four bidentate bridging and a monodentate carboxylic group, as well as one water molecular. The coordination polyhedron around each Sm 3+ ion can be described as bi-capped triangular prism geometry. The thermal decomposition behavior of the title complex in a static air atmosphere was investigated by TG-DTG and IR techniques

  1. Hydroxyl and molecular H2O diffusivity in a haploandesitic melt

    Science.gov (United States)

    Ni, Huaiwei; Xu, Zhengjiu; Zhang, Youxue

    2013-02-01

    H2O diffusion in a haploandesitic melt (a high-silica and Fe-free andesitic melt, NBO/T = 0.173) has been investigated at 1 GPa in a piston-cylinder apparatus. We adopted a double diffusion couple technique, in which one couple was composed of a nominally anhydrous glass with 0.01 wt.% H2O and a hydrous glass with 5.7 wt.% H2O, and the other contained the same nominally anhydrous glass and a hydrous glass with 3.3 wt.% H2O. Both couples were annealed in a single experimental run and hence experienced exactly the same P-T history, which is crucial for constraining the dependence of H2O diffusivity on water content. H2O concentration profiles were measured by both Fourier transform infrared (FTIR) microspectroscopy and confocal Raman microspectroscopy. Nearly identical profiles were obtained from Raman and FTIR methods for profile length >1 mm (produced at 1619-1842 K). By contrast, for profile lengths <100 μm (produced at 668-768 K), FTIR profiles show marked convolution effects compared to Raman profiles. A comparison between the short FTIR and Raman profiles indicates that the real spatial resolution (FWHM) of FTIR analyses is about 28 μm for a 7 μm wide aperture on ˜200 μm thick glasses. While the short profiles are not reliable for quantitative modeling, the long diffusion profiles at superliquidus temperatures can be fit reasonably well by a diffusivity model previously developed for felsic melts, in which molecular H2O (H2Om) is the only diffusive species and its diffusivity (D) increases exponentially with the content of total water (H2Ot). However, there is noticeable misfit of the data at low H2Ot concentrations, suggesting that OH diffusivity (DOH) cannot be neglected in this andesitic melt at high temperatures and low water contents. We hence develop a new fitting procedure that simultaneously fits both diffusion profiles from a single experimental run and accounts for the roles of both OH and H2Om diffusion. With this procedure, DOH/D is constrained

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

    Science.gov (United States)

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

    2014-11-01

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

  3. Quantitative evaluation of the effect of H2O degassing on the oxidation state of magmas

    Science.gov (United States)

    Lange, R. A.; Waters, L.

    2014-12-01

    The extent to which degassing of the H2O component affects the oxidation state of hydrous magmas is widely debated. Several researchers have examined how degassing of mixed H-C-O-S-Cl fluids may change the Fe3+/FeT ratio of various magmas, whereas our focus is on the H2O component. There are two ways that degassing of H2O by itself may cause oxidation: (1) the reaction: H2O (melt) + 2FeO (melt) = H2 (fluid) + Fe2O3 (melt), and/or (2) if dissolved water preferentially enhances the activity of ferrous vs. ferric iron in magmatic liquids. In this study, a comparison is made between the pre-eruptive oxidation states of 14 crystal-poor, jet-black obsidian samples (obtained from two Fe-Ti oxides) and their post-eruptive values (analyzed with the Wilson 1960 titration method tested against USGS standards). The obsidians are from Medicine Lake (CA), Long Valley (CA), and the western Mexican arc; all have low FeOT (1.1-2.1 wt%), rendering their Fe2+/Fe3+ ratios highly sensitive to the possible effects of substantial H2O degassing. The Fe-Ti oxide thermometer/oxybarometer of Ghiorso and Evans, (2008) gave temperatures for the 14 samples that range for 720 to 940°C and ΔNNO values of -0.9 to +1.4. With temperature known, the plagioclase-liquid hygrometer was applied and show that ≤ 6.5 wt% H2O was dissolved in the melts prior to eruption. In addition, pre-eruptive Cl and S concentrations were constrained on the basis of apatite analyses (Webster et al., 2009) and sulfur concentrations needed for saturation with pyrrhotite (Clemente et al., 2004), respectively. Maximum pre-eruptive chlorine and sulfur contents are 6000 and 200 ppm, respectively. After eruption, the rhyolites lost nearly all of their volatiles. Our results indicate no detectable change between pre- and post-eruptive Fe2+ concentrations, with an average deviation of ± 0.1 wt % FeO. Although degassing of large concentrations of S and/or Cl may affect the oxidation state of magmas, at the pre-eruptive levels

  4. Anti-inflammatory drugs. X. Hydrated pyrrolidinium [2-[(2,6-dichlorophenyl)amino]phenyl]acetate(HP.D.H2O).

    Science.gov (United States)

    Castellari, C; Comelli, F; Ottani, S

    2001-10-01

    In the solid-state structure of the title compound, C(4)H(10)N(+).C(14)H(10)Cl(2)NO(2)(-).H(2)O, the asymmetric unit contains one cation, one anion and a water molecule. There is a network of hydrogen bonds which is similar to that found in the hydrated diethylammonium diclofenac salt. A comparison is made of the molecular conformation of the anions in the two related structures.

  5. Experimental determination of liquidus H2O contents of haplogranite at deep-crustal conditions

    Science.gov (United States)

    Makhluf, A. R.; Newton, R. C.; Manning, C. E.

    2017-09-01

    The liquidus water content of a haplogranite melt at high pressure ( P) and temperature ( T) is important, because it is a key parameter for constraining the volume of granite that could be produced by melting of the deep crust. Previous estimates based on melting experiments at low P (≤0.5 GPa) show substantial scatter when extrapolated to deep crustal P and T (700-1000 °C, 0.6-1.5 GPa). To improve the high-P constraints on H2O concentration at the granite liquidus, we performed experiments in a piston-cylinder apparatus at 1.0 GPa using a range of haplogranite compositions in the albite (Ab: NaAlSi3O8)—orthoclase (Or: KAlSi3O8)—quartz (Qz: SiO2)—H2O system. We used equal weight fractions of the feldspar components and varied the Qz between 20 and 30 wt%. In each experiment, synthetic granitic composition glass + H2O was homogenized well above the liquidus T, and T was lowered by increments until quartz and alkali feldspar crystalized from the liquid. To establish reversed equilibrium, we crystallized the homogenized melt at the lower T and then raised T until we found that the crystalline phases were completely resorbed into the liquid. The reversed liquidus minimum temperatures at 3.0, 4.1, 5.8, 8.0, and 12.0 wt% H2O are 935-985, 875-900, 775-800, 725-775, and 650-675 °C, respectively. Quenched charges were analyzed by petrographic microscope, scanning electron microscope (SEM), X-ray diffraction (XRD), and electron microprobe analysis (EMPA). The equation for the reversed haplogranite liquidus minimum curve for Ab36.25Or36.25Qz27.5 (wt% basis) at 1.0 GPa is T = - 0.0995 w_{{{H}_{ 2} {O}}}^{ 3} + 5.0242w_{{{H}_{ 2} {O}}}^{ 2} - 88.183 w_{{{H}_{ 2} {O}}} + 1171.0 for 0 ≤ w_{{{H}_{ 2} {O}}} ≤ 17 wt% and T is in °C. We present a revised P - T diagram of liquidus minimum H2O isopleths which integrates data from previous determinations of vapor-saturated melting and the lower pressure vapor-undersaturated melting studies conducted by other workers on

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

    Science.gov (United States)

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

    2016-11-01

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

  7. Glass transition behaviour of the quaternary ammonium type ionic liquid, {[DEME][I] + H2O} mixtures

    International Nuclear Information System (INIS)

    Imai, Yusuke; Abe, Hiroshi; Matsumoto, Hitoshi; Shimada, Osamu; Hanasaki, Tomonori; Yoshimura, Yukihiro

    2011-01-01

    By a simple DTA system, the glass transition temperatures of the quaternary ammonium type ionic liquid, {N,N-diethyl-N-methyl-N-(2-methoxyethyl) ammonium iodide, [DEME][I] + H 2 O} mixtures after quick pre-cooling were measured as a function of water concentration (x mol% H 2 O). Results were compared with the previous results of {[DEME][BF 4 ] + H 2 O} mixtures in which double glass transitions were observed in the water concentration region of (16.5 to 30.0) mol% H 2 O. Remarkably, we observed the double glass transition phenomenon in {[DEME][I] + H 2 O} mixtures too, but the two-T g s regions lie towards the water-rich side of (77.5 to 85.0) mol% H 2 O. These clearly reflect the difference in the anionic effect between BF 4 - and I - on the water structure. The end of the glass-formation region of {[DEME][I] + H 2 O} mixtures is around x = 95.0 mol% H 2 O, and this is comparable to that of {[DEME][BF 4 ] + H 2 O} mixtures (x = 96.0 mol% H 2 O).

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

    Science.gov (United States)

    2012-01-01

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

  9. Poisoning of Ni-Based anode for proton conducting SOFC by H2S, CO2, and H2O as fuel contaminants

    Science.gov (United States)

    Sun, Shichen; Awadallah, Osama; Cheng, Zhe

    2018-02-01

    It is well known that conventional solid oxide fuel cells (SOFCs) based on oxide ion conducting electrolyte (e.g., yttria-stabilized zirconia, YSZ) and nickel (Ni) - ceramic cermet anodes are susceptible to poisoning by trace amount of hydrogen sulfide (H2S) while not significantly impacted by the presence of carbon dioxide (CO2) and moisture (H2O) in the fuel stream unless under extreme operating conditions. In comparison, the impacts of H2S, CO2, and H2O on proton-conducting SOFCs remain largely unexplored. This study aims at revealing the poisoning behaviors caused by H2S, CO2, and H2O for proton-conducting SOFCs. Anode-supported proton-conducting SOFCs with BaZe0.1Ce0.7Y0.1Yb0.1O3 (BZCYYb) electrolyte and Ni-BZCYYb anode and La0.6Sr0.4Co0.2Fe0.8O3 (LSCF) cathode as well as Ni-BZCYYb/BZCYYb/Ni-BZCYYb anode symmetrical cells were subjected to low ppm-level H2S or low percentage-level CO2 or H2O in the hydrogen fuel, and the responses in cell electrochemical behaviors were recorded. The results suggest that, contrary to conventional SOFCs that show sulfur poisoning and CO2 and H2O tolerance, such proton-conducting SOFCs with Ni-BZCYYb cermet anode seem to be poisoned by all three types of "contaminants". Beyond that, the implications of the experimental observations on understanding the fundamental mechanism of anode hydrogen electrochemical oxidation reaction in proton conducting SOFCs are also discussed.

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

    International Nuclear Information System (INIS)

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

    2012-01-01

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

  11. Studies on the direct synthesis of [O-15]-H2O

    International Nuclear Information System (INIS)

    Hagami, Eiichi; Murakami, Matsutaro; Takahashi, Kazuhiro; Kanno, Iwao; Aizawa, Yasuo; Hachiya, Takenori; Shoji, Yasuaki; Shishido, Fumio; Uemura, Kazuo

    1986-01-01

    A direct [O-15]-H 2 O synthesis method and its critical point of non-radioactive NH 4 + contamination were described. The 6.4 MeV deuterons were irradiated into the target chamber of 177 ml, filled up with 3.5 kg/cm 2 of 0.1 % H 2 in N 2 . [O-15]-H 2 O vapor was transported to PET room by He flow of 2.5 l/min through the teflon tubing of 2 mm in internal diameter and of 30 m in length. [O-15]-H 2 O was trapped in the vial containing 10 ml of saline and passed through Millipore filter. In this condition, the small amount of non-radioactive NH 4 + (24.9 ± 12.8 (1 SD) μg/dl, n = 23) was detected. This NH 4 + concentration varied from 25 to 11,000 μg/dl with changing H 2 amount in the target from 0.1 to 4.0 %. The NH 4 + concentration was kept lower than a normal range of the healthy human blood with 0.5 % or less H 2 in N 2 in the target. Therefore, 0.1 % of H 2 was used in clinical use. By the present method, a yield of approximately 7 mCi/μA of [O-15]-H 2 O saline was obtained. About 10 % of radioactive gases, corresponding to C 15 O, C 15 O 2 and N 2 15 O, were detected in the waste gas. The radiochemical and radionuclidic impurity was not detected in the saline. The biological tests for bacteria and pyrogen were all passed. In conclusion, the direct synthesis method provides [O-15]-H 2 O saline in the PET room with the simple handling and is convenient for the clinical use. (author)

  12. Uptake of methanol on mixed HNO3/H2O clusters: An absolute pickup cross section

    Science.gov (United States)

    Pysanenko, A.; Lengyel, J.; Fárník, M.

    2018-04-01

    The uptake of atmospheric oxidized organics on acid clusters is relevant for atmospheric new particle formation. We investigate the pickup of methanol (CH3OH) on mixed nitric acid-water clusters (HNO3)M(H2O)N by a combination of mass spectrometry and cluster velocity measurements in a molecular beam. The mass spectra of the mixed clusters exhibit (HNO3)m(H2O)nH+ series with m = 0-3 and n = 0-12. In addition, CH3OH.(HNO3)m(H2O)nH+ series with very similar patterns appear in the spectra after the methanol pickup. The velocity measurements prove that the undoped (HNO3)m(H2O)nH+ mass peaks in the pickup spectra originate from the neutral (HNO3)M(H2O)N clusters which have not picked up any CH3OH molecule, i.e., methanol has not evaporated upon the ionization. Thus the fraction of the doped clusters can be determined and the mean pickup cross section can be estimated, yielding σs ¯ ≈ 20 Å2. This is compared to the lower estimate of the mean geometrical cross section σg ¯ ≈ 60 Å2 obtained from the theoretical cluster geometries. Thus the "size" of the cluster corresponding to the methanol pickup is at least 3-times smaller than its geometrical size. We have introduced a method which can yield the absolute pickup cross sections relevant to the generation and growth of atmospheric aerosols, as illustrated in the example of methanol and nitric acid clusters.

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

    Science.gov (United States)

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

    2016-10-01

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

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

    International Nuclear Information System (INIS)

    Zhang Lili; Nie Yulun; Hu Chun; Hu Xuexiang

    2011-01-01

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

  15. Study of the reversible water vapour sorption process of MgSO4.7H2O and MgCl2.6H2O under the conditions of seasonal solar heat storage

    NARCIS (Netherlands)

    Ferchaud, C.; Zondag, H.A.; Veldhuis, J.B.J.; Boer, de R.

    2012-01-01

    The characterization of the structural, compositional and thermodynamic properties of MgSO4.7H2O and MgCl2.6H2O has been done using in-situ X-ray Diffraction and thermal analyses (TG/DSC) under practical conditions for seasonal heat storage (Tmax=150°C, p(H2O)=13 mbar). This study showed that these

  16. Organic micropollutants (OMPs) in natural waters: Oxidation by UV/H2O2 treatment and toxicity assessment.

    Science.gov (United States)

    Rozas, Oscar; Vidal, Cristiane; Baeza, Carolina; Jardim, Wilson F; Rossner, Alfred; Mansilla, Héctor D

    2016-07-01

    Organic micropollutants (OMPs) are ubiquitous in natural waters even in places where the human activity is limited. The presence of OMPs in natural water sources for human consumption encourages the evaluation of different water purification technologies to ensure water quality. In this study, the Biobío river (Chile) was selected since the watershed includes urban settlements and economic activities (i.e. agriculture, forestry) that incorporate a variety of OMPs into the aquatic environment, such as pesticides, pharmaceuticals and personal care products. Atrazine (herbicide), caffeine (psychotropic), diclofenac (anti-inflammatory) and triclosan (antimicrobial) in Biobío river water and in different stages of a drinking and two wastewater treatment plants downstream Biobío river were determined using solid phase extraction (SPE) and liquid chromatography/tandem mass spectrometry (LC-MS/MS) and electrospray ionization (ESI). Quantification of these four compounds showed concentrations in the range of 8 ± 2 to 55 ± 10 ng L(-1) in Biobío river water, 11 ± 2 to 74 ± 21 ng L(-1) in the drinking water treatment plant, and 60 ± 10 to 15,000 ± 1300 ng L(-1) in the wastewater treatment plants. Caffeine was used as an indicator of wastewater discharges. Because conventional water treatment technologies are not designed to eliminate some emerging organic pollutants, alternative treatment processes, UV and UV/H2O2, were employed. The transformation of atrazine, carbamazepine (antiepileptic), diclofenac and triclosan was investigated at laboratory scale. Both processes were tested at different UV doses and the Biobío river water matrix effects were evaluated. Initial H2O2 concentration used was 10 mg L(-1). Results showed that, the transformation profile obtained using UV/H2O2 at UV doses up to 900 mJ cm(-2), followed the trend of diclofenac > triclosan > atrazine > carbamazepine. Furthermore acute toxicity tests with Daphnia magna were carried

  17. Gradual crossover in molecular organization of stable liquid H2O at moderately high pressure and temperature

    DEFF Research Database (Denmark)

    Koga, Yoshikata; Westh, Peter; Yoshida, Koh

    2014-01-01

    temperature. The extrapolated temperature to zero p seems to be about 70 – 80 °C for points X and 90 – 110 °C for Y. Furthermore, the mid-points of X and Y seem to extrapolate to the triple point of liquid, ice Ih and ice III. Recalling that the zero x Gly extrapolation of point X and Y for binary aqueous...... of the step named point X and its end point Y. In analogy with another third and fourth derivative pair in binary aqueous solutions of glycerol, dα p /dx Gly and d2 α p /dx Gly 2, at 0.1 MPa (α p is the thermal expansivity and x Gly the mole fraction of solute glycerol) in our recent publication [J. Solution...... Chem. 43, 663-674 (2014); DOI:10.1007/s10953-013-0122-7], we argue that there is a gradual crossover in the molecular organization of pure H2O from a low to a high p-regions starting at point X and ending at Y at a fixed T. The crossover takes place gradually spanning for about 100 MPa at a fixed...

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

    Science.gov (United States)

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

    2018-04-03

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

  19. Ground and excited states of the [Fe(H2O)6]2+ and [Fe(H2O)6]3+ clusters: Insight into the electronic structure of the [Fe(H2O)6]2+ – [Fe(H2O)6]3+ complex

    Energy Technology Data Exchange (ETDEWEB)

    Miliordos, Evangelos; Xantheas, Sotiris S.

    2015-04-14

    We report the ground and low lying electronically excited states of the [Fe(H2O)6]2+ and [Fe(H2O)6]3+ clusters using multi-configuration electronic structure theory. In particular, we have constructed the Potential Energy Curves (PECs) with respect to the iron-oxygen distance when removing all water ligands at the same time from the cluster minima and established their correlation to the long range dissociation channels. Due to the fact that both the second and third ionization potentials of iron are larger than the one for water, the ground state products asymptotically correlate with dissociation channels that are repulsive in nature at large separations as they contain at least one H2O+ fragment and a positive metal center. The most stable equilibrium structures emanate – via intersections and/or avoided crossings – from the channels consisting of the lowest electronic states of Fe2+(5D; 3d6) or Fe3+(6S; 3d5) and six neutral water molecules. Upon hydration, the ground state of Fe2+(H2O)6 is a triply (5Tg) degenerate one with the doubly (5Eg) degenerate state lying slightly higher in energy. Similarly, Fe3+(H2O)6 has a ground state of 6Ag symmetry under Th symmetry. We furthermore examine a multitude of electronically excited states of many possible spin multiplicities, and report the optimized geometries for several selected states. The PECs for those cases are characterized by a high density of states. Focusing on the ground and the first few excited states of the [Fe(H2O)6]2+ and [Fe(H2O)6]3+ clusters, we studied their mutual interaction in the gas phase. We obtained the optimal geometries of the Fe2+(H2O)6 – Fe3+(H2O)6 gas phase complex for different Fe–Fe distances. For distances shorter than 6.0 Å, the water molecules in the respective first solvation shells located between the two metal centers were found to interact via weak hydrogen bonds. We examined a total of ten electronic states for this complex, including those corresponding to the

  20. The mid-IR Absorption Cross Sections of α- and β-NAT (HNO3 · 3H2O) in the range 170 to 185 K and of metastable NAD (HNO3 · 2H2O) in the range 172 to 182 K

    Science.gov (United States)

    Iannarelli, R.; Rossi, M. J.

    2015-11-01

    Growth and Fourier transform infrared (FTIR) absorption in transmission of the title nitric acid hydrates have been performed in a stirred flow reactor (SFR) under tight control of the H2O and HNO3 deposition conditions affording a closed mass balance of the binary mixture. The gas and condensed phases have been simultaneously monitored using residual gas mass spectrometry and FTIR absorption spectroscopy, respectively. Barrierless nucleation of the metastable phases of both α-NAT (nitric acid trihydrate) and NAD (nitric acid dihydrate) has been observed when HNO3 was admitted to the SFR in the presence of a macroscopic thin film of pure H2O ice of typically 1 µm thickness. The stable β-NAT phase was spontaneously formed from the precursor α-NAT phase through irreversible thermal rearrangement beginning at 185 K. This facile growth scheme of nitric acid hydrates requires the presence of H2O ice at thicknesses in excess of approximately hundred nanometers. Absolute absorption cross sections in the mid-IR spectral range (700-4000 cm-1) of all three title compounds have been obtained after spectral subtraction of excess pure ice at temperatures characteristic of the upper troposphere/lower stratosphere. Prominent IR absorption frequencies correspond to the antisymmetric nitrate stretch vibration (ν3(NO3-)) in the range 1300 to 1420 cm-1 and the bands of hydrated protons in the range 1670 to 1850 cm-1 in addition to the antisymmetric O-H stretch vibration of bound H2O in the range 3380 to 3430 cm-1 for NAT.

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

    Science.gov (United States)

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

    2017-11-07

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

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

    Science.gov (United States)

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

    2017-05-04

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

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

    NARCIS (Netherlands)

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

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

  4. A non-equilibrium ortho-to-para ratio of H2O in the Orion PDR

    NARCIS (Netherlands)

    Choi, Yunhee; van der Tak, Floris; Bergin, Edwin; Plume, Rene

    The ortho-to-para ratio (OPR) of H2O is lower than 1 at low temperature (<15 K) and increases to 3 at high temperature (> 40 K). The OPR of H2O is thus useful to study the formation mechanism of water. The measured OPRs of H2O is 2-3 in solar system comets (Mumma & Charnley, 2011) and in the

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

    Science.gov (United States)

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

    2017-09-01

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

  6. Crystallization in the systems Cu-I-HI-H2O and CuI-HI-H2O at elevated temperatures and pressures

    International Nuclear Information System (INIS)

    Popolitov, V.I.; Mininzon, Yu.M.

    1983-01-01

    Physicochemical investigation on synthesis and recrystallization of copper monoiodide monocrystals in the systems CU-I-HI-H 2 O and CuI-HI-W 2 O at high temperatures and pressures (200-300 deg and 50-160 atm) has been carried out. The optimum conditions for the growth of the Main tetrahedral facet (111) are clarified. The conditions are as follows: aqueous solution concentration Csub(HI)=32-35 mas.%, temperature 230-270 deg and external temperature gap 25-35 deg. Depending on synthesis conditions monocrystals CUI are prepared with different morphology of tetrahedral and cubooctahedral image. Kinetic regularities of CuI monocrystal preparation are presented and their physical properties, luminescence in particular, are studied

  7. Invited: Tailoring Platinum Group Metals Towards Optimal Activity for Oxygen Electroreduction to H2o and H2O2: From Extended Surfaces to Nanoparticles

    DEFF Research Database (Denmark)

    Stephens, Ifan

    2014-01-01

    ). The figure shows transmission electron miscroscopy images of 9 nm diameter PtxY nanoparticles, based on high angle annular dark field –scanning transmission electron microscopy (left) and Y, Pt and combined Pt+Y X-ray energy dispersive X-ray spectroscopy elemental maps. (a) as-prepared catalyst and (b) after......The slow kinetics of the 4-electron reduction of oxygen to H2O imposes a bottleneck against the widespread uptake of low temperature fuel cells in automotive vehicles. High loadings of platinum are required to drive the reaction; the limited supply of this precious metal limits the extent to which...... fuel cell technology could be scaled up.(1) The most widely used strategy towards decreasing the Pt loading is to alloy Pt with other late transition metals, in particular Ni or Co. (2-5) However, when tested in a fuel cell, these alloys are often susceptible towards degradation via dealloying.(6, 7...

  8. Experimental and kinetic study of the iodine reactivity in low pressure H2/O2/H2O/HI/Ar premixed flames

    International Nuclear Information System (INIS)

    Delicat, Y.G.

    2012-01-01

    To assess kinetics aspects of iodine chemistry in an environment of a severe accident in a Pressurized Water Reactor (PWR), at the laboratory scale, an experimental reactor named 'flat flame burner' has been implemented. Low pressure flames of H 2 /O 2 /Ar premixed gas seeded with known amounts of iodhydric acid and steam were studied. The quantification of chemical species (HI, H 2 O, OH) in such environment was obtained by specific analytical techniques (Fourier Transform Infrared absorption spectrometry, FTIR and Laser Induced Fluorescence, LIF), the evolution of the temperature was determined by LIF and by thermocouple measurements. Further assays were performed in a flow reactor in which gaseous molecular iodine was injected and transported in a stream or hydrogen flow and a strong temperature gradient, representative of the primary circuit in the case of a severe accident. The resulting gaseous species (I 2 and HI) were quantified by ICP-MS and UV-Visible spectrometry. This experimental database has been used as a support to develop a detailed kinetic mechanism for the {I, O, H} system. It is composed of 37 reversible reactions involving 5 iodinated species. The thermo-kinetic parameter database has been actualized by using theoretical chemistry tools and also completed with data found in the literature. Modelling was performed by using the PREMIX code for flame assays, and with the in IRSN's severe accident simulation code ASTEC/SOPHAREOS code for flow reactor assays. The comparison between experiment and modelling shows that this detailed mechanism is able to reproduce the iodine chemistry in conditions representative of a PWR severe accident. (author)

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

    Science.gov (United States)

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

    2017-02-08

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

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

    Science.gov (United States)

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

    2016-12-16

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

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

    Science.gov (United States)

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

    2017-06-29

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

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

    Directory of Open Access Journals (Sweden)

    CAIPING ZHUANG

    2013-07-01

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

  13. Cr6+-containing phases in the system CaO-Al2O3-CrO42--H2O at 23 °C

    Science.gov (United States)

    Pöllmann, Herbert; Auer, Stephan

    2012-01-01

    Synthesis and investigation of lamellar calcium aluminium hydroxy salts was performed to study the incorporation of chromate ions in the interlayer of lamellar calcium aluminium hydroxy salts. Different AFm-phases (calcium aluminate hydrate with alumina, ferric oxide, mono-anion phase) containing chromate were synthesized. These AFm-phases belong to the group of layered double hydroxides (LDHs). 3CaO·Al2O3·CaCrO4·nH2O and C3A·1/2Ca(OH)2·1/2CaCrO4·12H2O were obtained as pure phases and their different distinct interlayer water contents and properties determined. Solid solution of chromate-containing phases and tetracalcium-aluminate-hydrate (TCAH) were studied. The uptake of chromate into TCAH from solutions was proven. Chromate contents in solution decrease to <0.2 mg/l.

  14. Thermodynamic calculations in the system CH4-H2O and methane hydrate phase equilibria

    Science.gov (United States)

    Circone, S.; Kirby, S.H.; Stern, L.A.

    2006-01-01

    Using the Gibbs function of reaction, equilibrium pressure, temperature conditions for the formation of methane clathrate hydrate have been calculated from the thermodynamic properties of phases in the system CH4-H 2O. The thermodynamic model accurately reproduces the published phase-equilibria data to within ??2 K of the observed equilibrium boundaries in the range 0.08-117 MPa and 190-307 K. The model also provides an estimate of the third-law entropy of methane hydrate at 273.15 K, 0.1 MPa of 56.2 J mol-1 K-1 for 1/n CH4??H 2O, where n is the hydrate number. Agreement between the calculated and published phase-equilibria data is optimized when the hydrate composition is fixed and independent of the pressure and temperature for the conditions modeled. ?? 2006 American Chemical Society.

  15. A second polymorph with composition Co3(PO42·H2O

    Directory of Open Access Journals (Sweden)

    Yang Kim

    2008-10-01

    Full Text Available Single crystals of Co3(PO42·H2O, tricobalt(II bis[orthophosphate(V] monohydrate, were obtained under hydrothermal conditions. The compound is the second polymorph of this composition and is isotypic with its zinc analogue, Zn3(PO42·H2O. Three independent Co2+ cations are bridged by two independent orthophosphate anions. Two of the metal cations exhibit a distorted tetrahedral coordination while the third exhibits a considerably distorted [5 + 1] octahedral coordination environment with one very long Co—O distance of 2.416 (3 Å. The former cations are bonded to four different phosphate anions, and the latter cation is bonded to four anions (one of which is bidentate and one water molecule, leading to a framework structure. Additional hydrogen bonds of the type O—H...O stabilize this arrangement.

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

    Directory of Open Access Journals (Sweden)

    María I. Oloriz

    2014-04-01

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

  17. Dissociative phototionization cross sections of H2, SO2 and H2O

    International Nuclear Information System (INIS)

    Chung, Y.

    1989-01-01

    The partial photoionization cross sections of H 2 , SO 2 , and H 2 O were calculated from the measured photoionization branching ratios and the known total photoionization cross sections. The branching ratios were measured with a time-of-flight mass spectrometer and synchrotron radiation. The branching ratios Of H 2 , SO 2 , and H 2 O were measured for 100 ∼ 410, 150 ∼ 380 and 120 ∼ 720 angstrom. The author also measured the photoionization yield Of SO 2 from 520 to 665 angstrom using a double ion chamber and a glow discharge light source. The principle of a time-of-flight mass spectrometer is explained. New calculations were made to see how the design of the mass spectrometer, applied voltage, and kinetic energy of the ions affect the overall performance of the mass spectrometer. Several useful techniques that we used at the synchrotron for wavelength calibration and higher order suppression are also discussed

  18. Sustainable hydrocarbon fuels by recycling CO2 and H2O with renewable or nuclear energy

    DEFF Research Database (Denmark)

    Graves, Christopher R.; Ebbesen, Sune; Mogensen, Mogens Bjerg

    2011-01-01

    ) and biofuels have received the most attention, similar hydrocarbons can be produced without using fossil fuels or biomass. Using renewable and/or nuclear energy, carbon dioxide and water can be recycled into liquid hydrocarbon fuels in non-biological processes which remove oxygen from CO2 and H2O (the reverse...... of fuel combustion). Capture of CO2 from the atmosphere would enable a closed-loop carbon-neutral fuel cycle. This article critically reviews the many possible technological pathways for recycling CO2 into fuels using renewable or nuclear energy, considering three stages—CO2 capture, H2O and CO2...... by Fischer–Tropsch synthesis is identified as one of the most promising, feasible routes. An analysis of the energy balance and economics of this CO2 recycling process is presented. We estimate that the full system can feasibly operate at 70% electricity-to-liquid fuel efficiency (higher heating value basis...

  19. Product fine-structure resolved photodissociation dynamics: The A band of H2O

    International Nuclear Information System (INIS)

    Zhou, Linsen; Xie, Daiqian; Sun, Zhigang; Guo, Hua

    2014-01-01

    The photodissociation dynamics of H 2 O in its first absorption band is investigated on an accurate potential energy surface based on a large number of high-level ab initio points. Several ro-vibrational states of the parent molecule are considered. Different from most previous theoretical studies, the spin-orbit and Λ-doublet populations of the open-shell OH fragment are reported from full-dimensional wave packet calculations. The populations of the two spin-orbit manifolds are in most cases close to the statistical limit, but the Λ-doublet is dominated by the A ″ component, thanks largely to the fast in-plane dissociation of H 2 O(A ~1 A ′′ ). Comparisons with experimental data and a Franck-Condon model are generally very good, although some discrepancies exist

  20. Neutronics comparisons of d-Li and t-H2O neutron sources

    International Nuclear Information System (INIS)

    Doran, D.G.; Cierjacks, S.; Mann, F.M.; Greenwood, L.R.; Daum, E.

    1995-01-01

    Calculations were performed to compare the neutronics of two neutron source concepts which are candidates for an international fusion materials irradiation facility (IFMIF). One concept, d-Li, produces neutrons by stopping 35 MeV deuterons in a flowing lithium target. Criticism of this concept because of the high energy tail above 14 MeV gave rise to the t-H 2 O concept proposed by Cierjacks. It would generate neutrons below 14.6 MeV ( 2 O. Test volumes that met certain damage parameter criteria were estimated. Because of the softer spectra and somewhat lower yields for t-H 2 O, the d-Li concept was found to have a test volume advantage of a factor of 2 or more, depending on the material to be irradiated. ((orig.))

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

    International Nuclear Information System (INIS)

    Shimizu, Yuichi; Kawanishi, Shunichi; Suzuki, Nobutake

    1995-01-01

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

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

    KAUST Repository

    Ordoñez, Natalia Maria

    2014-02-13

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

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

    Science.gov (United States)

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

    2010-10-07

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

  4. Direct Coupling of Thermo- and Photocatalysis for Conversion of CO2 -H2 O into Fuels.

    Science.gov (United States)

    Zhang, Li; Kong, Guoguo; Meng, Yaping; Tian, Jinshu; Zhang, Lijie; Wan, Shaolong; Lin, Jingdong; Wang, Yong

    2017-12-08

    Photocatalytic CO 2 reduction into renewable hydrocarbon solar fuels is considered as a promising strategy to simultaneously address global energy and environmental issues. This study focused on the direct coupling of photocatalytic water splitting and thermocatalytic hydrogenation of CO 2 in the conversion of CO 2 -H 2 O into fuels. Specifically, it was found that direct coupling of thermo- and photocatalysis over Au-Ru/TiO 2 leads to activity 15 times higher (T=358 K; ca. 99 % CH 4 selectivity) in the conversion of CO 2 -H 2 O into fuels than that of photocatalytic water splitting. This is ascribed to the promoting effect of thermocatalytic hydrogenation of CO 2 by hydrogen atoms generated in situ by photocatalytic water splitting. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  5. Atmospheric chemistry of CF3O radicals: Reaction with H2O

    DEFF Research Database (Denmark)

    Wallington, T.J.; Hurley, M.D.; Schneider, W.F.

    1993-01-01

    Evidence is presented that CF3O radicals react with H2O in the gas phase at 296 K to give CF3OH and OH radicals. This reaction is calculated to be exothermic by 1.7 kcal mol-I implying a surprisingly strong CF3O-H bond energy of 120 +/- 3 kcal mol-1. Results from a relative rate experimental study...... suggest that the rate constant for the reaction of CF3O radicals with H2O lies in the range (0.2-4.0) X 10(-17) cm3 molecule-1 s-1. Implications for the atmospheric chemistry of CF3O radicals are discussed....

  6. Unusual H2O maser source near Herbig-Haro object number 11

    International Nuclear Information System (INIS)

    Lo, K.Y.; Morris, M.; Moran, J.M.; Haschick, A.D.

    1976-01-01

    Water emission spectra of an unusual source near Herbig-Haro (HH) 11 have been monitored over a 14-month period. Variations in the intensity and the radial velocity of the emission are noticeable on time scales as short as one day. At any given time, only one or two velocity components are present in the spectrum. The variations are such that each component appears and disappears at a fixed radial velocity, and new components appear at seemingly random velocities within a 40 km s -1 range. It is suggested that the exciting source is losing mass via a stellar wind, and that the H 2 O emission arises in the transition region between the cavity created by the stellar wind and the surrounding molecular medium. The proposed model can be tested by VLBI observations; an accurate position for the H 2 O maser source is required to determine the physical relationship between the maser source and the infrared or HH objects

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

    African Journals Online (AJOL)

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

  8. Quantitative analysis of H2O and CO2 in cordierite using polarized FTIR spectroscopy

    Science.gov (United States)

    Della Ventura, Giancarlo; Radica, Francesco; Bellatreccia, Fabio; Cavallo, Andrea; Capitelli, Francesco; Harley, Simon

    2012-11-01

    We report a FTIR (Fourier transform infrared) study of a set of cordierite samples from different occurrence and with different H2O/CO2 content. The specimens were fully characterized by a combination of techniques including optical microscopy, single-crystal X-ray diffraction, EMPA (electron microprobe analysis), SIMS (secondary ion mass spectrometry), and FTIR spectroscopy. All cordierites are orthorhombic Ccmm. According to the EMPA data, the Si/Al ratio is always close to 5:4; X Mg ranges from 76.31 to 96.63, and additional octahedral constituents occur in very small amounts. Extraframework K and Ca are negligible, while Na reaches the values up to 0.84 apfu. SIMS shows H2O up to 1.52 and CO2 up to 1.11 wt%. Optically transparent single crystals were oriented using the spindle stage and examined by FTIR micro-spectroscopy under polarized light. On the basis of the polarizing behaviour, the observed bands were assigned to water molecules in two different orientations and to CO2 molecules in the structural channels. The IR spectra also show the presence of small amounts of CO in the samples. Refined integrated molar absorption coefficients were calibrated for the quantitative microanalysis of both H2O and CO2 in cordierite based on single-crystal polarized-light FTIR spectroscopy. For H2O the integrated molar coefficients for type I and type II water molecules (ν3 modes) were calculated separately and are [I]ɛ = 5,200 ± 700 l mol-1 cm-2 and [II]ɛ = 13,000 ± 3,000 l mol-1 cm-2, respectively. For CO2 the integrated coefficient is \\varepsilon_{{{{CO}}_{ 2} }} = 19,000 ± 2,000 l mol-1 cm-2.

  9. A two-dimensional yttrium phthalate coordination polymer, [Y4(H2O ...

    Indian Academy of Sciences (India)

    Unknown

    polymer, [Y4(H2O)2(C8H4O4)6]∞, I. The Y ions in I are present in four different ... Co etc., the analogous lanthanide ions are also being investigated.2–10 The .... O(18). –237(3). –913(3). 7101(2). 37(1). O(19). –3693(3). –1348(3). 10459(3).

  10. Magnetic excitations in (VO)HPO4· 1/2 H2O

    International Nuclear Information System (INIS)

    Garrett, A.W.; Nagler, S.E.; Tennant, D.A.

    1997-01-01

    The magnetic excitations of an antiferromagnetic spin dimer system, (VO)HPO 4 · 1/2 H 2 O, are examined using inelastic neutron scattering. A dispersionless mode is found, consistent with expectations for a dimer excitation. The intensity variation of the mode reveals a V 4+ - V 4+ dimer separation of 4.43 angstrom, almost 50% larger than the originally expected length

  11. Cotransport of H+, lactate, and H2O in porcine retinal pigment epithelial cells

    DEFF Research Database (Denmark)

    Hamann, Steffen; Kiilgaard, Jens Folke; la Cour, Morten

    2003-01-01

    ) for the H(+) and lactate fluxes. The data suggest that H(2)O is cotransported along with H(+) and lactate ions in MCT1 localized to the retinal membrane. The study emphasizes the importance of this cotransporter in the maintenance of water homeostasis and pH in the subretinal space of a mammalian tissue...... and supports our previous study performed by an invasive technique in an amphibian tissue....

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

    Directory of Open Access Journals (Sweden)

    Zheng Gong

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

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

    Science.gov (United States)

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

    2011-06-01

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

  14. Mechano-chemical pathways to H2O and CO2 splitting

    Science.gov (United States)

    Vedadi, Mohammad H.; Haas, Stephan

    2011-10-01

    The shock-induced collapse of CO2-filled nanobubbles is investigated using molecular dynamics simulations based on a reactive force field. The energetic nanojet and high-pressure water hammer shock formed during and after collapse of the nanobubble trigger mechano-chemical H2O-CO2 reactions, some of which lead to splitting of water and formation of O2 molecules. The dominant pathways through which splitting of water molecules occur are identified.

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

    Directory of Open Access Journals (Sweden)

    Kristi M Porter

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

  16. H2O: A Hampton University-Hampton School District Outreach Program

    Science.gov (United States)

    Gueye, Paul; Young, William

    2011-04-01

    For many years, Hampton University (HU, Hampton, VA) has been collaborating with local schools of the Hampton City School District (HCS) in various areas that foster science education. This partnership between an HBCU and a local school district has been extended to a new level through a novel K-12 initiative:Hampton University-Hampton School District Outreach (H2O) program. This effort will target 9 schools out of the 34 schools from HCS, involve a total of 25 graduate students (5/year), 25 junior and senior undergraduate students (5/year) and 102 teachers (3/school). Faculty and students from seven STEM fields at HU will contribute by reaching out to Departments offering MS and PhD degrees in these areas. In addition to providing teaching experience to students, H2O will infuse research within the classrooms and offer a teacher professional development program, G5-12 students will present some research conducted throughout the year at a dedicated conference at HU and at the National Society of Black Physicists annual meeting, and a dedicated 2-day workshop in the fall with K-12 educators will provide a platform to share some outcomes of H2O. This program has reached out to several societies (NSBP, NSHP, APS, AAPT and AAPM) as a vehicle for teacher professional training, along with including an international component with Canada, France and Senegal. A review of recent collaborations and outcomes from this partnership will be provided and the status of the H2O program will be presented.

  17. Gradual crossover in molecular organization of stable liquid H2O at moderately high pressure and temperature

    Directory of Open Access Journals (Sweden)

    Yoshikata Koga

    2014-09-01

    Full Text Available Using the literature raw data of the speed of sound and the specific volume, the isothermal compressibility, κT, a second derivative thermodynamic quantity of G, was evaluated for liquid H2O in the pressure range up to 350 MPa and the temperature to 50 ºC. We then obtained its pressure derivative, dκT/dp, a third derivative numerically without using a fitting function to the κT data. On taking yet another p-derivative at a fixed T graphically without resorting to any fitting function, the resulting d2κT/dp2, a fourth derivative, showed a weak but clear step anomaly, with the onset of the step named point X and its end point Y. In analogy with another third and fourth derivative pair in binary aqueous solutions of glycerol, dαp/dxGly and d2αp/dxGly2, at 0.1 MPa (αp is the thermal expansivity and xGly the mole fraction of solute glycerol in our recent publication [J. Solution Chem. 43, 663-674 (2014; DOI:10.1007/s10953-013-0122-7], we argue that there is a gradual crossover in the molecular organization of pure H2O from a low to a high p-regions starting at point X and ending at Y at a fixed T. The crossover takes place gradually spanning for about 100 MPa at a fixed temperature. The extrapolated temperature to zero p seems to be about 70 – 80 °C for points X and 90 – 110 °C for Y. Furthermore, the mid-points of X and Y seem to extrapolate to the triple point of liquid, ice Ih and ice III. Recalling that the zero xGly extrapolation of point X and Y for binary aqueous glycerol at 0.1 MPa gives about the same T values respectively, we suggest that at zero pressure the region below about 70 °C the hydrogen bond network is bond-percolated, while above about 90 ºC there is no hydrogen bond network. Implication of these findings is discussed.

  18. Solid and gaseous inclusions in the EDML deep ice core: origins and implications for the physical properties of polar ice

    Science.gov (United States)

    Faria, S. H.; Kipfstuhl, S.; Garbe, C. S.; Bendel, V.; Weikusat, C.; Weikusat, I.

    2010-12-01

    The great value of polar deep ice cores stems mainly from two essential features of polar ice: its crystalline structure and its impurities. They determine the physical properties of the ice matrix and provide proxies for the investigation of past climates. Experience shows that these two essential features of polar ice manifest themselves in a multiscale diversity of dynamic structures, including dislocations, grain boundaries, solid particles, air bubbles, clathrate hydrates and cloudy bands, among others. The fact that these structures are dynamic implies that they evolve with time through intricate interactions between the crystalline structure, impurities, and the ice flow. Records of these interactions have been carefully investigated in samples of the EPICA deep ice core drilled in Dronning Maud Land, Antarctica (75°S, 0°E, 2882 m elevation, 2774.15 m core length). Here we show how the distributions of sizes and shapes of air bubbles correlate with impurities and the crystalline structure, how the interaction between moving grain boundaries and micro-inclusions changes with ice depth and temperature, as well as the possible causes for the abrupt change in ice rheology observed in the MIS6-MIS5e transition. We also discuss how these observations may affect the flow of the ice sheet and the interpretation of paleoclimate records. Micrograph of an EDML sample from 555m depth. One can identify air bubbles (dark, round objects), microinclusions (tiny defocused spots), and a grain boundary pinned by a bubble. The width of the image is 700 micrometers.

  19. Prediction of absolute infrared intensities for the fundamental vibrations of H2O2

    Science.gov (United States)

    Rogers, J. D.; Hillman, J. J.

    1981-01-01

    Absolute infrared intensities are predicted for the vibrational bands of gas-phase H2O2 by the use of a hydrogen atomic polar tensor transferred from the hydroxyl hydrogen atom of CH3OH. These predicted intensities are compared with intensities predicted by the use of a hydrogen atomic polar tensor transferred from H2O. The predicted relative intensities agree well with published spectra of gas-phase H2O2, and the predicted absolute intensities are expected to be accurate to within at least a factor of two. Among the vibrational degrees of freedom, the antisymmetric O-H bending mode nu(6) is found to be the strongest with a calculated intensity of 60.5 km/mole. The torsional band, a consequence of hindered rotation, is found to be the most intense fundamental with a predicted intensity of 120 km/mole. These results are compared with the recent absolute intensity determinations for the nu(6) band.

  20. Nonlinear feedback drives homeostatic plasticity in H2O2 stress response

    Science.gov (United States)

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

    2017-01-01

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

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

    Science.gov (United States)

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

    2016-03-01

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

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

    Directory of Open Access Journals (Sweden)

    Milady Mendoza-Rodríguez

    2017-11-01

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

  3. Experimental study on SI engine fuelled with butanol–gasoline blend and H2O addition

    International Nuclear Information System (INIS)

    Feng, Renhua; Yang, Jing; Zhang, Daming; Deng, Banglin; Fu, Jianqin; Liu, Jingping; Liu, Xiaoqiang

    2013-01-01

    Highlights: • Ignition timing has been optimized. • 1% H 2 O has been added. • Positive results have been achieved in engine torque, BSEC, CO emissions and HC emissions. • NOx and CO 2 emissions go up. - Abstract: An experimental study was conducted on a single cylinder motorcycle engine for two operating modes of full load and partial load at 6500 rpm and 8500 rpm with pure gasoline and 35% volume butanol–gasoline blend. The engine ignition timing for 35% volume butanol–gasoline blend has been optimized, and 1% volume H 2 O has also been added to the butanol–gasoline blend fuel. Engine performance parameters, fuel economy and emissions have been measured and analyzed. The experimental results showed that engine torque, BSEC, CO emissions and HC emissions are better than that of pure gasoline at both full load and partial load with 35% volume butanol and 1% H 2 O addition, combined with the modified ignition timing. But NOx and CO 2 emissions are worse than that of the original level of pure gasoline

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

    International Nuclear Information System (INIS)

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

    1990-01-01

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

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

    Directory of Open Access Journals (Sweden)

    Ou Shulin

    2017-01-01

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

  6. Thermochemistry of the reactions between CN+ and H2O in the gas phase

    Science.gov (United States)

    Ijjaali, Fatima; Alcami, Manuel; Mo, Otilia; Yanez, Manuel

    The [H2, C, N, O]+ potential energy surface (PES) has been explored by means of high-level ab initio calculations, carried out in the framework of the G2 theory. From this survey we concluded that the predominant products of the CN+ +H2O reaction are the result of the dissociation of HNCOH+ species and to a much lesser extent of the CNHOH+ cation to yield CNH+ +OH. According to our results HCN+ should not be a product of this reaction because all pathways leading to its formation are unfavourable with regards to other competitive processes. Other reactive channels lead to the formation of the H2ONC+ structure which dissociates into CN + H2O+. The loss of NH(3Σ) and O(3P) seems to take place following spin-forbidden reaction paths through an intersystem crossing between the singlet and the triplet PESs. The global minimum of the PES, H2NCO+ is easily accessible and should lead to the loss of carbon monoxide which has not been experimentally observed in CN+ + H2O reactions. We cannot oOEer a clear explanation for this disagreement between theory and experiment.

  7. Circumstellar H2O maser emission associated with four late-type stars

    International Nuclear Information System (INIS)

    Johnston, K.J.; Spencer, J.H.; Bowers, P.F.

    1985-01-01

    The positions and structure of H2O maser associated with four long-period stars were measured using the VLA, and the results are discussed. The four stars observed were: RX Boo; R Aq1; RR Aq1; and NML Cyg. The spatial resolution of the VLA measurements was 0.07 arcsec. The H2O maser emission features appear as unresolved knots distributed over an area of no more than 0.4 arcsec. The velocity and spatial characteristics of the maser regions in R Aq1 and RR Aq1 were found to change considerably over time. The estimated sizes of the H2O maser emission were 8 x 10 to the 14th for RX Boo, R Aq1, and RR Aq1. The supergiant star NML Cyg had the largest maser region (10 to the 16th) which is comparable to that of VY CMa. The positional accuracy for individual maser features ranged between 0.03 and 0.09 arcsec. However, the precise location of the maser emission relative to the stellar photocenter did not fit the velocity and spatial distributions of the emission and therefore may be inappropriate as a standard for comparisons of stellar reference frames. 20 references

  8. H2O Megamasers toward Radio-bright Seyfert 2 Nuclei

    Science.gov (United States)

    Zhang, J. S.; Liu, Z. W.; Henkel, C.; Wang, J. Z.; Coldwell, G. V.

    2017-02-01

    Using the Effelsberg-100 m telescope, we perform a successful pilot survey on H2O maser emission toward a small sample of radio-bright Seyfert 2 galaxies with a redshift larger than 0.04. The targets were selected from a large Seyfert 2 sample derived from the spectroscopic Sloan Digital Sky Survey Data Release 7 (SDSS-DR7). One source, SDSS J102802.9+104630.4 (z ˜ 0.0448), was detected four times during our observations, with a typical maser flux density of ˜30 mJy and a corresponding (very large) luminosity of ˜1135 L ⊙. The successful detection of this radio-bright Seyfert 2 and an additional tentative detection support our previous statistical results that H2O megamasers tend to arise from Seyfert 2 galaxies with large radio luminosity. The finding provides further motivation for an upcoming larger H2O megamaser survey toward Seyfert 2s with particularly radio-bright nuclei with the basic goal to improve our understanding of the nuclear environment of active megamaser host galaxies. Based on observations with the 100 m telescope of the MPIfR (Max-Planck-Institut für Radioastronomie) at Effelsberg.

  9. OH radicals distribution in an Ar-H2O atmospheric plasma jet

    Science.gov (United States)

    Li, L.; Nikiforov, A.; Xiong, Q.; Britun, N.; Snyders, R.; Lu, X.; Leys, C.

    2013-09-01

    Recently, plasma jet systems found numerous applications in the field of biomedicine and treatment of temperature-sensitive materials. OH radicals are one of the main active species produced by these plasmas. Present study deals with the investigation of RF atmospheric pressure plasma jet in terms of OH radicals production by admixture of H2O into argon used as a feed gas. Generation of OH radicals is studied by laser-induced fluorescence spectroscopy. The excitation dynamics of OH radicals induced by the laser photons is studied by time-resolved spectroscopy. It is shown that vibrational and rotational energy transfer processes, which are sensitive to the surrounding species, can lead to the complication in the OH radicals diagnostics at high pressure and have to be considered during experiments. The axial and radial 2D maps of absolute densities of hydroxyl radicals at different water contents are obtained. The highest density of 1.15 × 1020 m-3 is measured in the plasma core for the case of 0.3% H2O. In the x-y-plane, the OH density steeply decreases within a range of ±2 mm from its maximum value down to 1018 m-3. The effect of H2O addition on the generation of OH radicals is investigated and discussed.

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

    Directory of Open Access Journals (Sweden)

    Huilian Qiao

    2016-01-01

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

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

    Directory of Open Access Journals (Sweden)

    Mehdi Bihamta

    2017-01-01

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

  12. Effects of substituting D2O for H2O on SANS measurements of hydrating cement

    International Nuclear Information System (INIS)

    Sabine, T.M.; Prior, M.J.

    2002-01-01

    Full text: Small angle neutron scattering (SANS) measurements of cement have been found useful in the investigation of the shape and growth of particles formed during hydration. Calorimetric measurements of hydrating cement samples have shown that the substitution of D 2 O for H 2 O has the effect of slowing the hydration process. In order to throw some light on this phenomenon, we have measured SANS profiles from cement samples hydrating in H 2 O and D 2 O. This involved obtaining SANS profiles at half-hourly intervals during the initial stage of hydration. The only instruments capable of this at present are located at the Hahn-Meitner Institute in Berlin and at the Nuclear Physics Institute at Rez near Prague. Initial experiments carried out on the V12a UltraSANS diffractometer at The Hahn-Meitner Institute were only partially successful owing to excessive multiple scattering in the D 2 O samples. Subsequent measurements were therefore carried out on the similar instrument at Rez near Prague which operates at a shorter neutron wavelength. Results from these measurements show profound differences in the evolution of cements hydrating in D 2 O and those hydrating in H 2 O

  13. Crystal structure of Sm(NO3)3x6H2O

    International Nuclear Information System (INIS)

    Espenbetov, A.A.; Gerr, R.G.; Struchkov, Yu.T.; Sal'nikova, N.A.; Akimov, V.M.; Odinets, Z.K.

    1985-01-01

    X-ray diffraction study of a salt, prepared when mixing concentrated nitric acid solutions of NaNO 3 and Sm(NO 3 ) 3 , has been carried out. It is established, that the salt is a concretion of two crystals: NaNO 3 and Sm(NO 3 ) 3 x6H 2 O (1). X-ray diffraction study of 1 is carried out (lambda Mo, diffractometer, 1511 reflections, the method of heavy atom, the least square method in anisotropic approximation up to R=0.0348). The crystals of 1 are triclinic: a=6.755, b=9.168, c=11.684 A, α=69.93, β=88.86, γ=69.28, Z=2, Fedorov group P anti 1. Symmetery of 10-vertex coordination polyhedron (CP) of Sm atom is close to Csub(s). Sm atom coordination can be described as 4;5:1. Four H 2 O molecules are included into CP, at the expense of two remaining H 2 O molecules CP are bound with each other

  14. THE MAGNETIZED ENVIRONMENT OF THE W3(H2O) PROTOSTARS

    International Nuclear Information System (INIS)

    Chen, Huei-Ru; Rao, Ramprasad; Liu, Sheng-Yuan; Wilner, David J.

    2012-01-01

    We present the first interferometric polarization map of the W3(OH) massive star-forming region observed with the Submillimeter Array (SMA) at 878 μm with an angular resolution of 1.''5 (about 3 × 10 3 AU). Polarization is detected in the W3(H 2 O) hot core, an extended emission structure in the northwest of W3(H 2 O), and part of the W3(OH) ultracompact H II region. The W3(H 2 O) hot core is known to be associated with a synchrotron jet along the east-west direction. In this core, the inferred magnetic field orientation is well aligned with the synchrotron jet and close to the plane of sky. Using the Chandrasekhar-Fermi method with the observed dispersion in polarization angle, we estimate a plane-of-sky magnetic field strength of 17.0 mG. Combined with water maser Zeeman measurements, the total magnetic field strength is estimated to be 17.1 mG, comparable to the field strength estimated from the synchrotron model. The magnetic field energy dominates over turbulence in this core. In addition, the depolarization effect is discerned in both SMA and James Clerk Maxwell Telescope measurements. Despite the great difference in angular resolutions and map extents, the polarization percentage shows a similar power-law dependence with the beam averaged column density. We suggest that the column density may be an important factor to consider when interpreting the depolarization effect.

  15. Features of the structure of phospho- and arsenouranic acids of the composition of HPUO2x4H2O and HAsUO6x4H2O

    International Nuclear Information System (INIS)

    Chernorukov, N.G.; Karyakin, N.V.; Chernorukov, G.N.

    1994-01-01

    The structure of crystal phases of the composition HPUO 6 x4H 2 O and HAsUO 6 x4H 2 O has been studied using the methods of IR spectroscopy, thermography, X-ray phase analysis and calorimetry. The nature and binding energy of water within the compounds mentioned are determined. 10 refs., 2 figs

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

    International Nuclear Information System (INIS)

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

    2013-01-01

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

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

    Science.gov (United States)

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

    2017-03-27

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

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

    Science.gov (United States)

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

    2016-12-01

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

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

    Science.gov (United States)

    Park, Woo Hyun

    2018-04-01

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

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

    Science.gov (United States)

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

    2017-03-01

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

  1. Synergistic effects and kinetics thermal behaviour of petroleum coke/biomass blends during H2O co-gasification

    International Nuclear Information System (INIS)

    Edreis, Elbager M.A.; Luo, Guangqian; Li, Aijun; Xu, Chaofen; Yao, Hong

    2014-01-01

    Highlights: • Sugar cane bagasse and blends gasification presented two stages at all H 2 O values. • Petroleum coke showed only one char gasification stage at (>700 °C) at 75% H 2 O. • Significant interactions are existed in the both reaction stages of samples. • Higher H 2 O concentration and PC content lead to higher kinetic parameter values. • All the models are successfully utilized to predict the experimental data. - Abstract: This study investigates the possible synergistic interactions between the Sudanese lower sulphur petroleum coke (PC) and sugar cane bagasse (SCB) during H 2 O co-gasification with three concentration values (25%, 50% and 75% v/v) using a thermogravimetric analyser (TGA) at 20 °C/min. The kinetic thermal behaviour, and effects of both H 2 O concentration and fuel blending ratio were investigated. The results show that, significant interactions existed in both reaction stages of samples, and become less when PC content and H 2 O concentration are 50%. Petroleum coke showed only one char gasification stage at (>700 °C) at 75% H 2 O. Some kinetics models like homogeneous and shrinking core models were studied by the Coats–Redfern method in order to observe the optimum reaction mechanism for the H 2 O gasification of samples, describe the best reactive behaviour and determine the kinetic parameters. The results showed that, the co-gasification behaviour and kinetic parameters have a significantly influenced by increasing both H 2 O concentration and PC content. The boundary controlled reaction model (R2) shows the lowest values of activation energy (E) for all samples and H 2 O concentrations. Finally, all the models are successfully utilized to predict the experimental data under all H 2 O concentration values

  2. Probing Metal Carbonation Reactions of CO2 in a Model System Containing Forsterite and H2O Using Si-29, C-13 Magic Angle Sample Spinning NMR Spectroscopy

    Science.gov (United States)

    Hu, J.; Kwak, J.; Hoyt, D. W.; Sears, J. A.; Rosso, K. M.; Felmy, A. R.

    2009-12-01

    Ex situ solid state NMR have been used for the first time to study fundamental mineral carbonation processes and reaction extent relevant to geologic carbon sequestration using a model silicate mineral forsterite (Mg2SiO4)+scCO2 with and without H2O. Run conditions were 80C and 96 bar. Si-29 NMR clearly shows that in the absence of CO2, the role of H2O is to hydrolyze surface Mg-O-Si bonds to produce Mg2+, and mono- and oligomeric hydroxylated silica species. The surface hydrolysis products contain only Q0 (Si(OH)4) and Q1 (Si(OH)3OSi) species. An equilibrium between Q0, Q1 and Mg2+ with a saturated concentration equivalent to less than 3.2% of the Mg2SiO4 conversion is obtained at a reaction time of up to 7 days. Using scCO2 without H2O, no reaction is observed within 7 days. Using both scCO2 and H2O, the surface reaction products for silica are mainly Q3 (SiOH(OSi)3) species accompanied by a lesser amount of Q2 (Si(OH)2(OSi)2) and Q4 (Si(OSi)4). However, no Q0 and Q1 were detected, indicating the carbonic acid formation/deprotonation and magnesite (MgCO3) precipitation reactions are faster than the forsterite hydrolysis process. Thus it can be concluded that the Mg2SiO4 hydrolysis process is the rate limiting step of the overall mineral carbonation process. Si-29 NMR combined with XRD, TEM, SAED and EDX further reveal that the reaction is a surface reaction with the Mg2SiO4 crystallite in the core and with condensed Q2-Q4 species forming amorphous surface layers. C-13 MAS NMR identified a possible reaction intermediates as (MgCO3)4*Mg(OH)2*5H2O. However, at long reaction times only crystallite magnesite MgCO3 products are observed. This research is part of a broader effort at PNNL to develop experimental tools and fundamental insights into chemical transformations affecting subsurface CO2 reactive transport. Si-29 (left) and C-13 (right) MAS NMR spectra of Mg2SiO4 under various reaction conditions. Si-29 NMR reveals that in scCO2 without H2O, no reaction is

  3. Oxidation and Condensation of Zinc Fume From Zn-CO2-CO-H2O Streams Relevant to Steelmaking Off-Gas Systems

    International Nuclear Information System (INIS)

    Bronson, Tyler Mark; Ma, Naiyang; Zhu, Liang Zhu; Sohn, Hong Yong

    2017-01-01

    Here the objective of this research was to study the condensation of zinc vapor to metallic zinc and zinc oxide solid under varying environments to investigate the feasibility of in-process separation of zinc from steelmaking off-gas dusts. Water vapor content, temperature, degree of cooling, gas composition, and initial zinc partial pressure were varied to simulate the possible conditions that can occur within steelmaking off-gas systems, limited to Zn-CO 2 -CO-H 2 O gas compositions. The temperature of deposition and the effect of rapidly quenching the gas were specifically studied. A homogeneous nucleation model for applicable experiments was applied to the analysis of the experimental data. It was determined that under the experimental conditions, oxidation of zinc vapor by H 2 O or CO 2 does not occur above 1108 K (835 °C) even for highly oxidizing streams (CO 2 /CO = 40/7). Rate expressions that correlate CO 2 and H 2 O oxidation rates to gas composition, partial pressure of water vapor, temperature, and zinc partial pressure were determined to be as follows: Rate ((mol)/(m 2 s)) = 406 exp ((−50.2kJ/mol)/(RT)) (pZnpCO 2 − PCO/K eq CO 2 ) ((mol)/(m 2 xs)) Rate (((mol)/(m 2 s))) = 32.9 exp (((−13.7kJ/mol)/(RT))) (pZnPH 2 O − PH 2 /K eq H 2 O) ((mol)/(m 2 xs)). It was proven that a rapid cooling rate (500 K/s) significantly increases the ratio of metallic zinc to zinc oxide as opposed to a slow cooling rate (250 K/s). SEM analysis found evidence of heterogeneous growth of ZnO as well as of homogeneous formation of metallic zinc. The homogeneous nucleation model fit well with experiments where only metallic zinc deposited. An expanded model with rates of oxidation by CO 2 and H 2 O as shown was combined with the homogenous nucleation model and then compared with experimental data. The calculated results based on the model gave a reasonable fit to the measured data. For the conditions used in this study, the rate equations for the oxidation of zinc by

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

    Science.gov (United States)

    Srithep, Sirinthip; Phattarapattamawong, Songkeart

    2017-06-01

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

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

    Science.gov (United States)

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

    2011-01-01

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

  6. Nickel and platinum in high-temperature H2O + HCl fluids: Implications for hydrothermal mobilization

    Science.gov (United States)

    Scholten, Lea; Watenphul, Anke; Beermann, Oliver; Testemale, Denis; Ames, Doreen; Schmidt, Christian

    2018-03-01

    The dissolution of NiS and NiAs (nickeline) in 0.1 and 1 molal HCl at 400 °C, 80 MPa, and of PtAs2 (sperrylite) and Pt metal in 1 and 6.86 molal HCl at 500 °C, 80 MPa was studied in-situ using synchrotron radiation X-ray fluorescence and absorption spectroscopy. The Pt concentration in the fluid averaged 8 · 10-5 molal (12.8 ppm) during dissolution of Pt metal in 6.86 molal HCl, and was below the minimum detection limit (mdl; 2.6 · 10-5 molal) in all other experiments. Dissolution of NiS was congruent or nearly congruent. Equilibrium was attained rapidly in about 250 min at an initial HCl concentration of 1 molal HCl, and in about 500 min at 0.1 molal HCl. Addition of HCl resulted in a large increase in the Ni solubility from 7.2 · 10-3 molal Ni (423 ppm) at 0.1 molal HCl to 8.72 · 10-2 molal Ni (4959 ppm) at 1 molal HCl. Dissolution of NiAs in 0.1 and 1 molal HCl was incongruent. A steady state was not reached even at a run duration of more than 16 h, and the maximum recorded Ni concentrations in the fluid were much lower than the Ni solubility in the corresponding experiments with NiS at the same HCl molality. Measured K-edge XANES spectra in comparison with literature data indicated that arsenic in the fluid was present as As(V) and that nickel complexed with Cl and H2O as tetrahedral [NiCl2(H2O)2]0 and [NiCl3(H2O)]- and octahedral [NiCl2(H2O)4]0 species. In addition, Raman spectra of H2O + NiCl2 and H2O + NiCl2 + HCl solutions and of H2O + HCl fluids reacted with NiS crystals were acquired at temperatures (T) up to 600 °C and pressures (P) up to 1.15 GPa. All spectra at T ≥ 300 °C and P conflict with the information from published XAS data. The results of this study demonstrate that nickel is readily mobilized by acidic chloridic hydrothermal fluids, but platinum remains practically immobile in such fluids at any HCl concentration that is conceivable to occur in nature. Therefore, the enrichment of Pt relative to Ni in footwall-type deposits in the

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

    Science.gov (United States)

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

    2014-01-01

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

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

    Science.gov (United States)

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

    2017-08-19

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

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

    Science.gov (United States)

    Czech, Bożena

    2017-05-01

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

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

    Science.gov (United States)

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

    2016-12-08

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

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

    Science.gov (United States)

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

    2011-11-01

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

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

    NARCIS (Netherlands)

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

    2017-01-01

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

  13. Hydrothermal synthesis and structure of nickel(II) metavanadate monohydrate, NiV2O6.H2O

    International Nuclear Information System (INIS)

    Marcos, M.D.; Amoros, P.; Beltran-Porter, A.; Ramirez de Arellano, M.C.

    1995-01-01

    The structure of NiV 2 O 6 .H 2 O consists of infinite chains of [VO 4 ] tetrahedra running along the [100] direction connected by isolated [Ni 2 O 8 (H 2 O) 2 ] dimeric entities to build up a three-dimensional network. A valence-bond analysis allows the identification of the O atoms of the water molecules. (orig.)

  14. Crystallization and Characterization of a New Magnesium Sulfate Hydrate MgSO4.11H2O

    NARCIS (Netherlands)

    Genceli, F.E.; Lutz, M.; Spek, A.L.; Witkamp, G.J.

    2007-01-01

    The MgSO4 crystal hydrate formed below approximately 0 °C was proven to be the undecahydrate, MgSO4 • 11H2O (meridianiite) instead of the reported dodecahydrate MgSO4 • 12H2O. The crystals were grown from solution by eutectic freeze and by cooling crystallization. The crystal structure analysis and

  15. The Tunable Bandgap of AB-Stacked Bilayer Graphene on SiO2 with H2O Molecule Adsorption

    International Nuclear Information System (INIS)

    Wang Tao; Guo Qing; Liu Yan; Wang Wen-Bo; Sheng Kuang; Ao Zhi-Min; Yu Bin

    2011-01-01

    The atomic and electronic structures of AB-stacking bilayer graphene (BLG) in the presence of H 2 O molecules are investigated by density functional theory calculations. For free-standing BLG, the bandgap is opened to 0.101 eV with a single H 2 O molecule adsorbed on its surface. The perfectly suspended BLG is sensitive to H 2 O adsorbates, which break the BLG lattice symmetry and open an energy gap. While a single H 2 O molecule is adsorbed on the BLG surface with a SiO 2 substrate, the bandgap widens to 0.363 eV. Both the H 2 O molecule adsorption and the oxide substrate contribute to the BLG bandgap opening. The phenomenon is interpreted with the charge transfer process in 2D carbon nanostructures. (condensed matter: electronic structure, electrical, magnetic, and optical properties)

  16. DC sputter deposition of amorphous indium-gallium-zinc-oxide (a-IGZO) films with H2O introduction

    International Nuclear Information System (INIS)

    Aoi, Takafumi; Oka, Nobuto; Sato, Yasushi; Hayashi, Ryo; Kumomi, Hideya; Shigesato, Yuzo

    2010-01-01

    Amorphous indium-gallium-zinc-oxide (a-IGZO) films were deposited by dc magnetron sputtering with H 2 O introduction and how the H 2 O partial pressure (P H 2 O ) during the deposition affects the electrical properties of the films was investigated in detail. Resistivity of the a-IGZO films increased dramatically to over 2 x 10 5 Ωcm with increasing P H 2 O to 2.7 x 10 -2 Pa while the hydrogen concentration in the films increased to 2.0 x 10 21 cm -3 . TFTs using a-IGZO channels deposited under P H 2 O at 1.6-8.6 x 10 -2 Pa exhibited a field-effect mobility of 1.4-3.0 cm 2 /Vs, subthreshold swing of 1.0-1.6 V/decade and on-off current ratio of 3.9 x 10 7 -1.0 x 10 8 .

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

    Science.gov (United States)

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

    2017-05-01

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

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

    Science.gov (United States)

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

    2017-05-23

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

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

    Science.gov (United States)

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

    2016-01-01

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

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

    Science.gov (United States)

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

    2015-10-01

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

  1. On Estimating the Mass of Keplerian Accretion Disks in H2O Maser Galaxies

    Science.gov (United States)

    Kuo, C. Y.; Reid, M. J.; Braatz, J. A.; Gao, F.; Impellizzeri, C. M. V.; Chien, W. T.

    2018-06-01

    H2O maser disks with Keplerian rotation in active galactic nuclei offer a clean way to determine accurate black hole mass and the Hubble constant. An important assumption made in using a Keplerian H2O maser disk for measuring black hole mass and the Hubble constant is that the disk mass is negligible compared to the black hole mass. A simple and useful model of Huré et al. can be used to test this assumption. In that work, the authors apply a linear disk model to a position–dynamical mass diagram and re-analyze position–velocity data from H2O maser disks associated with active galactic nuclei. They claim that a maser disk with nearly perfect Keplerian rotation could have a disk mass comparable to the black hole mass. This would imply that ignoring the effects of disk self-gravity can lead to large systematic errors in the measurement of black hole mass and the Hubble constant. We examine their methods and find that their large estimated disk masses of Keplerian disks are likely the result of their use of projected instead of three-dimensional position and velocity information. To place better constraints on the disk masses of Keplerian maser systems, we incorporate disk self-gravity into a three-dimensional Bayesian modeling program for maser disks and also evaluate constraints based on the physical conditions for disks that support water maser emission. We find that there is little evidence that disk masses are dynamically important at the ≲1% level compared to the black holes.

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

    Science.gov (United States)

    Wang, Feifei; van Halem, Doris; Liu, Gang; Lekkerkerker-Teunissen, Karin; van der Hoek, Jan Peter

    2017-10-01

    H 2 O 2 residuals from advanced oxidation processes (AOPs) may have critical impacts on the microbial ecology and performance of subsequent biological treatment processes, but little is known. The objective of this study was to evaluate how H 2 O 2 residuals influence sand systems with an emphasis on dissolved organic carbon (DOC) removal, microbial activity change and bacterial community evolution. The results from laboratory batch studies showed that 0.25 mg/L H 2 O 2 lowered DOC removal by 10% while higher H 2 O 2 concentrations at 3 and 5 mg/L promoted DOC removal by 8% and 28%. A H 2 O 2 dosage of 0.25 mg/L did not impact microbial activity (as measured by ATP) while high H 2 O 2 dosages, 1, 3 and 5 mg/L, resulted in reduced microbial activity of 23%, 37% and 37% respectively. Therefore, DOC removal was promoted by the increase of H 2 O 2 dosage while microbial activity was reduced. The pyrosequencing results illustrated that bacterial communities were dominated by Proteobacteria. The presence of H 2 O 2 showed clear influence on the diversity and composition of bacterial communities, which became more diverse under 0.25 mg/L H 2 O 2 but conversely less diverse when the dosage increased to 5 mg/L H 2 O 2 . Anaerobic bacteria were found to be most sensitive to H 2 O 2 as their growth in batch reactors was limited by both 0.25 and 5 mg/L H 2 O 2 (17-88% reduction). In conclusion, special attention should be given to effects of AOPs residuals on microbial ecology before introducing AOPs as a pre-treatment to biological (sand) processes. Additionally, the guideline on the maximum allowable H 2 O 2 concentration should be properly evaluated. Copyright © 2017 The Author(s). Published by Elsevier Ltd.. All rights reserved.

  3. Analysis of H2O in silicate glass using attenuated total reflectance (ATR) micro-FTIR spectroscopy

    Science.gov (United States)

    Lowenstern, Jacob B.; Pitcher, Bradley W.

    2013-01-01

    We present a calibration for attenuated total reflectance (ATR) micro-FTIR for analysis of H2O in hydrous glass. A Ge ATR accessory was used to measure evanescent wave absorption by H2O within hydrous rhyolite and other standards. Absorbance at 3450 cm−1 (representing total H2O or H2Ot) and 1630 cm−1 (molecular H2O or H2Om) showed high correlation with measured H2O in the glasses as determined by transmission FTIR spectroscopy and manometry. For rhyolite, wt%H2O=245(±9)×A3450-0.22(±0.03) and wt%H2Om=235(±11)×A1630-0.20(±0.03) where A3450 and A1630 represent the ATR absorption at the relevant infrared wavelengths. The calibration permits determination of volatiles in singly polished glass samples with spot size down to ~5 μm (for H2O-rich samples) and detection limits of ~0.1 wt% H2O. Basaltic, basaltic andesite and dacitic glasses of known H2O concentrations fall along a density-adjusted calibration, indicating that ATR is relatively insensitive to glass composition, at least for calc-alkaline glasses. The following equation allows quantification of H2O in silicate glasses that range in composition from basalt to rhyolite: wt%H2O=(ω×A3450/ρ)+b where ω = 550 ± 21, b = −0.19 ± 0.03, ρ = density, in g/cm3, and A3450 is the ATR absorbance at 3450 cm−1. The ATR micro-FTIR technique is less sensitive than transmission FTIR, but requires only a singly polished sample for quantitative results, thus minimizing time for sample preparation. Compared with specular reflectance, it is more sensitive and better suited for imaging of H2O variations in heterogeneous samples such as melt inclusions. One drawback is that the technique can damage fragile samples and we therefore recommend mounting of unknowns in epoxy prior to polishing. Our calibration should hold for any Ge ATR crystals with the same incident angle (31°). Use of a different crystal type or geometry would require measurement of several H2O-bearing standards to provide a crystal

  4. Global Distribution of Solid Ammonium Sulfate Aerosols and their Climate Impact Acting as Ice Nuclei

    Science.gov (United States)

    Zhou, C.; Penner, J.

    2017-12-01

    Laboratory experiments show that liquid ammonium sulfate particles effloresce when RHw is below 34% to become solid and dissolve when RHw is above 79%. Solid ammonium sulfate aerosols can act as heterogeneous ice nuclei particles (INPs) to form ice particles in deposition mode when the relative humidity over ice is above 120%. In this study we used the coupled IMPACT/CAM5 model to track the efflorescence and deliquescence processes of ammonium sulfate. Results show that about 20% of the total simulated pure sulfate aerosol mass is in the solid state and is mainly distributed in the northern hemisphere (NH) from 50 hPa to 200 hPa. When these solid ammonium sulfate aerosols are allowed to act as ice nuclei particles, they act to increase the ice water path in the NH and reduce ice water path in the tropics. The addition of these particles leads to a positive net radiative effect at the TOA ranging from 0.5-0.9 W/m2 depending on the amounts of other ice nuclei particles (e.g., dust, soot) used in the ice nucleation process. The short-term climate feedback shows that the ITCZ shifts northwards and precipitation increases in the NH. There is also an average warming of 0.05-0.1 K near the surface (at 2 meter) in the NH which is most obvious in the Arctic region.

  5. Structure of Sr3V10O28.22H2O

    International Nuclear Information System (INIS)

    Nieto, J.M.; Salagre, P.; Medina, F.; Sueiras, J.E.; Solans, X.

    1993-01-01

    The crystal structure of hydrated strontium decavanadate, Sr 3 V 10 O 28 .22H 2 O, has been determined. It contains two types of strontium ions: the first is coordinated to seven water molecules which define a pentagonal bipyramid; the second bonds to five molecules of water and three O atoms of different decavanadate ions, thereby bridging between decavanadate ions to produce layers of formula [Sr 2 V 10 O 38 H 20 ] n on the crystallographic plane (100). The heptacoordinated Sr and the five molecules of water associated with it are located between the different layers. (orig.)

  6. Numerically Exact Calculation of Rovibrational Levels of Cl^-H_2O

    Science.gov (United States)

    Wang, Xiao-Gang; Carrington, Tucker

    2014-06-01

    Large amplitude vibrations of Van der Waals clusters are important because they reveal large regions of a potential energy surface (PES). To calculate spectra of Van der Waals clusters it is common to use an adiabatic approximation. When coupling between intra- and inter-molecular coordinates is important non-adiabatic coupling cannot be neglected and it is therefore critical to develop and test theoretical methods that couple both types of coordinates. We have developed new product basis and contracted basis Lanczos methods for Van der Waals complexes and tested them by computing rovibrational energy levels of Cl^-H_2O. The new product basis is made of functions of the inter-monomer distance, Wigner functions that depend on Euler angles specifying the orientation of H_2O with respect to a frame attached to the inter-monomer Jacobi vector, basis functions for H_2O vibration, and Wigner functions that depend on Euler angles specifying the orientation of the inter-monomer Jacobi vector with respect to a space-fixed frame. An advantage of this product basis is that it can be used to make an efficient contracted basis by replacing the vibrational basis functions for the monomer with monomer vibrational wavefunctions. Due to weak coupling between intra- and inter-molecular coordinates, only a few tens of monomer vibrational wavefunctions are necessary. The validity of the two new methods is established by comparing energy levels with benchmark rovibrational levels obtained with polyspherical coordinates and spherical harmonic type basis functions. For all bases, product structure is exploited to calculate eigenvalues with the Lanczos algorithm. For Cl^-H_2O, we are able, for the first time, to compute accurate splittings due to tunnelling between the two equivalent C_s minima. We use the PES of Rheinecker and Bowman (RB). Our results are in good agreement with experiment for the five fundamental bands observed. J. Rheinecker and J. M. Bowman, J. Chem. Phys. 124 131102

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

    Science.gov (United States)

    Lv, Jinlong; Liang, Tongxiang

    2016-08-01

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

  8. H2O-induced trigonal-to-tetrahedral transition in boron zeolites

    International Nuclear Information System (INIS)

    Fois, E.; Gamba, A.; Trudu, F.; Tabacchi, G.

    2008-01-01

    The behaviour of a protonated boron-containing zeolite at intermediate hydration degree has been investigated by means of periodic DFT approaches. Results of a combined room-temperature Car-Parrinello molecular dynamics blue-moon path sampling simulation indicate that, in the line with experimental findings, the BO 3 /Si-OH acid site typical of dry samples is converted to a hydrated H 3 O + hydrogen bonded to tetrahedral BO 4 - at moderate water content (four H 2 O per B site) with an activation free barrier of the order of few k T.

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

    International Nuclear Information System (INIS)

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

    2011-01-01

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

  10. HIFI Spectroscopy of H2O Submillimeter Lines in Nuclei of Actively Star-forming Galaxies

    Science.gov (United States)

    Liu, L.; Weiß, A.; Perez-Beaupuits, J. P.; Güsten, R.; Liu, D.; Gao, Y.; Menten, K. M.; van der Werf, P.; Israel, F. P.; Harris, A.; Martin-Pintado, J.; Requena-Torres, M. A.; Stutzki, J.

    2017-09-01

    We present a systematic survey of multiple velocity-resolved H2O spectra using Herschel/Heterodyne Instrument for the Far Infrared (HIFI) toward nine nearby actively star-forming galaxies. The ground-state and low-excitation lines (E up ≤ 130 K) show profiles with emission and absorption blended together, while absorption-free medium-excitation lines (130 K ≤ E up ≤ 350 K) typically display line shapes similar to CO. We analyze the HIFI observation together with archival SPIRE/PACS H2O data using a state-of-the-art 3D radiative transfer code that includes the interaction between continuum and line emission. The water excitation models are combined with information on the dust and CO spectral line energy distribution to determine the physical structure of the interstellar medium (ISM). We identify two ISM components that are common to all galaxies: a warm ({T}{dust}˜ 40{--}70 K), dense (n({{H}})˜ {10}5{--}{10}6 {{cm}}-3) phase that dominates the emission of medium-excitation H2O lines. This gas phase also dominates the far-IR emission and the CO intensities for {J}{up}> 8. In addition, a cold ({T}{dust}˜ 20{--}30 K), dense (n({{H}})˜ {10}4{--}{10}5 {{cm}}-3), more extended phase is present. It outputs the emission in the low-excitation H2O lines and typically also produces the prominent line absorption features. For the two ULIRGs in our sample (Arp 220 and Mrk 231) an even hotter and more compact (R s ≤ 100 pc) region is present, which is possibly linked to AGN activity. We find that collisions dominate the water excitation in the cold gas and for lines with {E}{up}≤slant 300 K and {E}{up}≤slant 800 K in the warm and hot component, respectively. Higher-energy levels are mainly excited by IR pumping.

  11. Molecular distribution in the comae of H2O-comets: an analytic model

    International Nuclear Information System (INIS)

    Yamamoto, T.

    1981-01-01

    Density distribution in cometary comae resulting from photodissociation, ionization and ion-molecule reaction of H 2 O is investigated in an analytic manner. It is assumed that particles expand isotropically around the nucleus, and that each species has its own constant radial velocity. Formulae for the density distribution of photochemical products are presented throughout the coma, and approximate formulae are given for the distribution of ion-molecule reaction products in the inner coma. Characteristics of the density profile are discussed on the basis of these analytic formulae. (Auth.)

  12. Study of L-ascorbic acid (vitamin C)/H 2O mixture across glass transition

    Science.gov (United States)

    Migliardo, F.; Branca, C.; Faraone, A.; Magazù, S.; Migliardo, P.

    2001-07-01

    In this paper, we report quasi elastic neutron scattering (QENS) spectra of vitamin C aqueous solutions, obtained using MIBEMOL spectrometer (LLB). The main purpose of this work is to characterize the relaxational and vibrational properties of the Vitamin C/H 2O system below and above the glass transition temperature by analysing the low-frequency neutron scattering spectra. The determination of the relative weight of vibrational over relaxational contributions allows to get information on the fragility degree of this peculiar hydrogen-bond system.

  13. Effective diffusion coefficients of 3H2O in several porous materials

    International Nuclear Information System (INIS)

    Terashima, Yutaka; Kumaki, Toru.

    1976-01-01

    Diffusion coefficients of radionuclides in some porous structural materials and porous components of earth stratum are important as the basis for the safety evaluation of the storage and disposal of radioactive wastes. In our previous works, the method of analysis and experiment using a permeative type diffusion cell for measurement of effective diffusion coefficient was established, and experimental results were reported. In this paper, effective diffusion coefficients of 3 H 2 O in mortar, concrete, brick, clay layer, and sand layer were measured, and characteristics of these pore structure were discussed on the basis of tourtusity factor. (auth.)

  14. Seasonal change in CO2 and H2O exchange between grassland and atmosphere

    Directory of Open Access Journals (Sweden)

    T. Oikawa

    Full Text Available The seasonal change in CO2 flux over an artificial grassland was analyzed from the ecological and meteorological point of view. This grassland contains C3 and C4 plants; the three dominant species belonging to the Gramineae; Festuca elatior (C3 dominated in early spring, and Imperata cylindrica (C4 and Andropogon virginicus (C4 grew during early summer and became dominant in mid-summer. CO2 flux was measured by the gradient method, and the routinely observed data for the surface-heat budget were used to analyze the CO2 and H2O exchange between the grassland and atmosphere. From August to October in 1993, CO2 flux was reduced to around half under the same solar-radiation conditions, while H2O flux decreased 20% during the same period. The monthly values of water use efficiency, i.e., ratio of CO2 flux to H2O flux decreased from 5.8 to 3.3 mg CO2/g H2O from August to October, the Bowen ratio increased from 0.20 to 0.30, and the ratio of the bulk latent heat transfer coefficient CE to the sensible heat transfer coefficient CH was maintained around 0.40-0.50. The increase in the Bowen ratio was explained by the decrease in air temperature from 22.3 °C in August to 16.6 °C in October without considering biological effects such as stomatal closure on the individual leaves. The nearly constant CE/CH ratios suggested that the contribution ratio of canopy resistance to aerodynamic resistance did not change markedly, although the meteorological conditions changed seasonally. The decrease in the water use efficiency, however, suggested that the photosynthetic rate decreased for individual leaves from August to October under the same radiation conditions. Diurnal variations of CO2 exchange were simulated by the multi-layer canopy model taking into account the differences in the stomatal conductance and photosynthetic pathway between C3 and C4 plants. The results suggested that C4 plants played a major role in the CO2 exchange in August, the contribution

  15. Seasonal change in CO2 and H2O exchange between grassland and atmosphere

    Directory of Open Access Journals (Sweden)

    N. Saigusa

    1996-03-01

    Full Text Available The seasonal change in CO2 flux over an artificial grassland was analyzed from the ecological and meteorological point of view. This grassland contains C3 and C4 plants; the three dominant species belonging to the Gramineae; Festuca elatior (C3 dominated in early spring, and Imperata cylindrica (C4 and Andropogon virginicus (C4 grew during early summer and became dominant in mid-summer. CO2 flux was measured by the gradient method, and the routinely observed data for the surface-heat budget were used to analyze the CO2 and H2O exchange between the grassland and atmosphere. From August to October in 1993, CO2 flux was reduced to around half under the same solar-radiation conditions, while H2O flux decreased 20% during the same period. The monthly values of water use efficiency, i.e., ratio of CO2 flux to H2O flux decreased from 5.8 to 3.3 mg CO2/g H2O from August to October, the Bowen ratio increased from 0.20 to 0.30, and the ratio of the bulk latent heat transfer coefficient CE to the sensible heat transfer coefficient CH was maintained around 0.40-0.50. The increase in the Bowen ratio was explained by the decrease in air temperature from 22.3 °C in August to 16.6 °C in October without considering biological effects such as stomatal closure on the individual leaves. The nearly constant CE/CH ratios suggested that the contribution ratio of canopy resistance to aerodynamic resistance did not change markedly, although the meteorological conditions changed seasonally. The decrease in the water use efficiency, however, suggested that the photosynthetic rate decreased for individual leaves from August to October under the same radiation conditions. Diurnal variations of CO2 exchange were simulated by the multi-layer canopy model taking into account the differences in the stomatal conductance and photosynthetic pathway between C3 and C4 plants. The results suggested that C4 plants played a major role in the CO2 exchange in August, the contribution

  16. Seasonal change in CO2 and H2O exchange between grassland and atmosphere

    Science.gov (United States)

    Saigusa, N.; Liu, S.; Oikawa, T.; Watanabe, T.

    1996-03-01

    The seasonal change in CO2 flux over an artificial grassland was analyzed from the ecological and meteorological point of view. This grassland contains C3 and C4 plants; the three dominant species belonging to the Gramineae; Festuca elatior (C3) dominated in early spring, and Imperata cylindrica (C4) and Andropogon virginicus (C4) grew during early summer and became dominant in mid-summer. CO2 flux was measured by the gradient method, and the routinely observed data for the surface-heat budget were used to analyze the CO2 and H2O exchange between the grassland and atmosphere. From August to October in 1993, CO2 flux was reduced to around half under the same solar-radiation conditions, while H2O flux decreased 20% during the same period. The monthly values of water use efficiency, i.e., ratio of CO2 flux to H2O flux decreased from 5.8 to 3.3 mg CO2/g H2O from August to October, the Bowen ratio increased from 0.20 to 0.30, and the ratio of the bulk latent heat transfer coefficient CE to the sensible heat transfer coefficient CH was maintained around 0.40-0.50. The increase in the Bowen ratio was explained by the decrease in air temperature from 22.3 °C in August to 16.6 °C in October without considering biological effects such as stomatal closure on the individual leaves. The nearly constant CE/CH ratios suggested that the contribution ratio of canopy resistance to aerodynamic resistance did not change markedly, although the meteorological conditions changed seasonally. The decrease in the water use efficiency, however, suggested that the photosynthetic rate decreased for individual leaves from August to October under the same radiation conditions. Diurnal variations of CO2 exchange were simulated by the multi-layer canopy model taking into account the differences in the stomatal conductance and photosynthetic pathway between C3 and C4 plants. The results suggested that C4 plants played a major role in the CO2 exchange in August, the contribution of C4 plants

  17. Determination and modeling for the solubility of Na_2WO_4·2H_2O and Na_2MoO_4·2H_2O in the (Na"+ + MoO_4"2"− + WO_4"2"− + SO_4"2"− + H_2O) system

    International Nuclear Information System (INIS)

    Ning, Pengge; Xu, Weifeng; Cao, Hongbin; Xu, Hongbin

    2016-01-01

    Highlights: • The solubility of Na_2MoO_4·2H_2O and Na_2WO_4·2H_2O in Na_2MoO_4–Na_2WO_4–Na_2SO_4–H_2O were performed. • The solubility of sodium tungstate dihydrate in Na_2WO_4–Na_2SO_4–H_2O was determined. • The new model was established via regressing the published and the determined data. • The Pitzer parameter and the solubility product constant of the salt in solution were calculated. • The model was used to estimate the solubility of the sodium molybdate and sodium tungstate. - Abstract: The solubility of sodium tungstate dihydrate and sodium molybdate dihydrate in the (Na_2MoO_4 + Na_2WO_4 + Na_2SO_4 + H_2O) system was studied using experimental and calculated methods. The osmotic coefficient of sodium tungstate was fitted to calculate the thermodynamics parameters of (Na_2WO_4 + H_2O) system. The solubility of sodium tungstate dihydrate was determined using the dynamic method in Na_2WO_4–Na_2SO_4–H_2O to establish the new model which can provide an estimate the solubility of sodium tungstate dihydrate in various conditions, combined with the data published, the solubility of sodium tungstate dihydrate and the sodium molybdate dihydrate in quaternary system of (Na_2MoO_4 + Na_2WO_4 + Na_2SO_4 + H_2O) was estimated using the parameters of the two ternary systems of (Na_2WO_4 + Na_2SO_4 + H_2O) and (Na_2MoO_4 + Na_2SO_4 + H_2O). The results show that the AARD is always small and the calculated value is basically consistent with the experimental values for the system studied.

  18. A Sequential Method to Prepare Polymorphs and Solvatomorphs of [Fe(1,3-bpp)2 ](ClO4 )2 ⋅nH2 O (n=0, 1, 2) with Varying Spin-Crossover Behaviour.

    Science.gov (United States)

    Bartual-Murgui, Carlos; Codina, Carlota; Roubeau, Olivier; Aromí, Guillem

    2016-08-26

    Two polymorphs of the spin crossover (SCO) compound [Fe(1,3-bpp)2 ](ClO4 )2 (1 and 2; 1,3-bpp=2-(pyrazol-1-yl)-6-(pyrazol-3-yl)pyridine) were prepared using a novel, stepwise procedure. Crystals of 1 deposit from dry solvents, while 2 is obtained from a solid-state procedure, by sequentially removing lattice H2 O molecules from the solvatomorph [Fe(1,3-bpp)2 ](ClO4 )2 ⋅2 H2 O (2⋅2 H2 O), using single-crystal-to-single-crystal (SCSC) transformations. Hydrate 2⋅2 H2 O is obtained through the same reaction as 1, now with 2.5 % of water added. Compounds 2 and 2⋅2 H2 O are unstable in the atmosphere and absorb or lose one equivalent of water, respectively, to both yield the stable solvatomorph [Fe(1,3-bpp)2 ](ClO4 )2 ⋅H2 O (2⋅H2 O), also following SCSC processes. The four derivatives have been characterised by single-crystal X-ray diffraction (SCXRD). Furthermore, the homogeneity of the various compounds as well as their SCSC interconversions have been confirmed by powder X-ray diffraction (PXRD). Polymorphs 1 and 2 exhibit abrupt SCO behaviour near room temperature with T1/2↑ =279/316 K and T1/2↓ =276/314 K (near 40 K of shift) and different cooperativity. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

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

    Science.gov (United States)

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

    2016-09-01

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

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

    Science.gov (United States)

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

    2017-12-01

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

  1. Adsorption and dissociation of H2O on Al(1 1 1) surface by density functional theory calculation

    International Nuclear Information System (INIS)

    Guo, F.Y.; Long, C.G.; Zhang, J.; Zhang, Z.; Liu, C.H.; Yu, K.

    2015-01-01

    Highlights: • O 2 on Al(1 1 1) surface can spontaneously dissociate, but H 2 O can not. • H 2 O, OH and H on top sites are favorable on Al(1 1 1) surface. • O on the hollow (fcc) site is preferred. • O which plays a key role in the dissociate reaction of H 2 O. - Abstract: Using the first-principles calculations method based on the density functional theory, we systematically study the adsorption behavior of a single molecular H 2 O on a clean and a pre-adsorbed O atom Al(1 1 1) surface, and also its corresponding dissociation reactions. The equilibrium configuration on top, bridge, and hollow (fcc and hcp) site were determined by relaxation of the system relaxation. The adsorptions of H 2 O, OH and H on top sites are favorable on the Al(1 1 1) surface, while that of O on the hollow (fcc) site is preferred. The results show that the hydrogen atom dissociating from H 2 O needs a 248.32 kJ/mol of energy on clean Al(1 1 1) surface, while the dissociating energy decreases to 128.53 kJ/mol with the aid of the O absorption. On the other hand, these phenomena indicate that the dehydrogenated reaction energy barrier of the pre-adsorbed O on metal surface is lower than that of on a clean one, because O can promote the dehydrogenation of H 2 O

  2. Quantum chemical study of the structure, spectroscopy and reactivity of NO+.(H2O) n=1-5 clusters.

    Science.gov (United States)

    Linton, Kirsty A; Wright, Timothy G; Besley, Nicholas A

    2018-03-13

    Quantum chemical methods including Møller-Plesset perturbation (MP2) theory and density functional theory (DFT) have been used to study the structure, spectroscopy and reactivity of NO + (H 2 O) n =1-5 clusters. MP2/6-311++G** calculations are shown to describe the structure and spectroscopy of the clusters well. DFT calculations with exchange-correlation functionals with a low fraction of Hartree-Fock exchange give a binding energy of NO + (H 2 O) that is too high and incorrectly predict the lowest energy structure of NO + (H 2 O) 2 , and this error may be associated with a delocalization of charge onto the water molecule directly binding to NO + Ab initio molecular dynamics (AIMD) simulations were performed to study the NO + (H 2 O) 5 [Formula: see text] H + (H 2 O) 4 + HONO reaction to investigate the formation of HONO from NO + (H 2 O) 5 Whether an intracluster reaction to form HONO is observed depends on the level of electronic structure theory used. Of note is that methods that accurately describe the relative energies of the product and reactant clusters did not show reactions on the timescales studied. This suggests that in the upper atmosphere the reaction may occur owing to the energy present in the NO + (H 2 O) 5 complex following its formation.This article is part of the theme issue 'Modern theoretical chemistry'. © 2018 The Author(s).

  3. Sustained Submicromolar H2O2 Levels Induce Hepcidin via Signal Transducer and Activator of Transcription 3 (STAT3)*

    Science.gov (United States)

    Millonig, Gunda; Ganzleben, Ingo; Peccerella, Teresa; Casanovas, Guillem; Brodziak-Jarosz, Lidia; Breitkopf-Heinlein, Katja; Dick, Tobias P.; Seitz, Helmut-Karl; Muckenthaler, Martina U.; Mueller, Sebastian

    2012-01-01

    The peptide hormone hepcidin regulates mammalian iron homeostasis by blocking ferroportin-mediated iron export from macrophages and the duodenum. During inflammation, hepcidin is strongly induced by interleukin 6, eventually leading to the anemia of chronic disease. Here we show that hepatoma cells and primary hepatocytes strongly up-regulate hepcidin when exposed to low concentrations of H2O2 (0.3–6 μm), concentrations that are comparable with levels of H2O2 released by inflammatory cells. In contrast, bolus treatment of H2O2 has no effect at low concentrations and even suppresses hepcidin at concentrations of >50 μm. H2O2 treatment synergistically stimulates hepcidin promoter activity in combination with recombinant interleukin-6 or bone morphogenetic protein-6 and in a manner that requires a functional STAT3-responsive element. The H2O2-mediated hepcidin induction requires STAT3 phosphorylation and is effectively blocked by siRNA-mediated STAT3 silencing, overexpression of SOCS3 (suppressor of cytokine signaling 3), and antioxidants such as N-acetylcysteine. Glycoprotein 130 (gp130) is required for H2O2 responsiveness, and Janus kinase 1 (JAK1) is required for adequate basal signaling, whereas Janus kinase 2 (JAK2) is dispensable upstream of STAT3. Importantly, hepcidin levels are also increased by intracellular H2O2 released from the respiratory chain in the presence of rotenone or antimycin A. Our results suggest a novel mechanism of hepcidin regulation by nanomolar levels of sustained H2O2. Thus, similar to cytokines, H2O2 provides an important regulatory link between inflammation and iron metabolism. PMID:22932892

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

    Science.gov (United States)

    Samuni, Amram; Maimon, Eric; Goldstein, Sara

    2017-08-01

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

  5. HF/H2O2 treated graphite felt as the positive electrode for vanadium redox flow battery

    Science.gov (United States)

    He, Zhangxing; Jiang, Yingqiao; Meng, Wei; Jiang, Fengyun; Zhou, Huizhu; Li, Yuehua; Zhu, Jing; Wang, Ling; Dai, Lei

    2017-11-01

    In order to improve the electrochemical performance of the positive graphite felt electrode in vanadium flow redox battery, a novel method is developed to effectively modify the graphite felt by combination of etching of HF and oxidation of H2O2. After the etching of HF for the graphite felt at ambient temperature, abundant oxygen-containing functional groups were further introduced on the surface of graphite felt by hydrothermal treatment using H2O2 as oxidant. Benefiting from the surface etching and introduction of functional groups, mass transfer and electrode process can be improved significantly on the surface of graphite felt. VO2+/VO2+ redox reaction on the graphite felt modified by HF and H2O2 jointly (denote: GF-HF/H2O2) exhibits superior electrochemical kinetics in comparison with the graphite felt modified by single HF or H2O2 treatment. The cell using GF-HF/H2O2 as the positive electrode was assembled and its electrochemical properties were evaluated. The increase of energy efficiency of 4.1% for GF-HF/H2O2 at a current density of 50 mA cm-2 was obtained compared with the pristine graphite felt. The cell using GF-HF/H2O2 also demonstrated higher discharge capacity. Our study revealed that HF/H2O2 treatment is an efficient method to enhance the electrochemical performance of graphite felt, further improving the comprehensive energy storage performance of the vanadium flow redox battery.

  6. A model for analysis and design of H2O-LiBr absorption heat pumps

    International Nuclear Information System (INIS)

    Bakhtiari, Bahador; Fradette, Louis; Legros, Robert; Paris, Jean

    2011-01-01

    An experimental and simulation analysis of a laboratory single-stage H 2 O-LiBr absorption heat pump with a cooling capacity of 14 kW has been performed. Design characteristics of the machine are given and experimental results obtained from the variation of the five most influential parameters are presented. The machine performance, as described by the coefficient of performance (COP) and cooling capacity was then measured at different flow rates and temperatures of the external cool and hot water loops and for different temperatures of produced chilled water. A design and dimensioning model of H 2 O-LiBr absorption heat pumps was developed. First, the steady-state simulation results of the model were compared with experimental measurements. Close agreement between experimental and simulation results was found. Results also show that the heat pump can adequately operate over a wide range of generator input energy and chilled water temperature; the cooling water flow rate and temperature significantly affect the performance of the machine. Finally, the capability of the model is illustrated by dimensioning an absorption heat pump implemented in a Kraft process.

  7. Structure and Dynamics in Formamide-(H2O)3: A Water Pentamer Analogue.

    Science.gov (United States)

    Blanco, Susana; Pinacho, Pablo; López, Juan Carlos

    2017-12-21

    Water self-association dominates the formation of microsolvated molecular clusters which may give rise to complex structures resembling those of pure water clusters. We present a rotational study of the complex formamide-(H 2 O) 3 formed in a supersonic jet and several monosubstituted isotopologues. Formamide and water molecules form a four-body sequential cycle through N-H···O, O-H···O, and O-H···O═C hydrogen bonds, resulting in a chiral structure with a nonplanar skeleton that can be overlapped to that of water pentamer. The analysis of the 14 N-nucleus quadrupole coupling effects shows the depletion of the electron density of the N atom lone pair with respect to the bare formamide that affects the amide group C-N and C═O distances. The study of the observed tunneling doublets shows that formamide-(H 2 O) 3 follows a path to invert its structure driven by the flipping of water subunits and passing through successive nonplanar configurations, a motion reminiscent of the pseudorotation of water pentamer.

  8. A second polymorph with composition Co3(PO4)2·H2O

    Science.gov (United States)

    Lee, Young Hoon; Clegg, Jack K.; Lindoy, Leonard F.; Lu, G. Q. Max; Park, Yu-Chul; Kim, Yang

    2008-01-01

    Single crystals of Co3(PO4)2·H2O, tricobalt(II) bis­[ortho­phosphate(V)] monohydrate, were obtained under hydro­thermal conditions. The compound is the second polymorph of this composition and is isotypic with its zinc analogue, Zn3(PO4)2·H2O. Three independent Co2+ cations are bridged by two independent orthophosphate anions. Two of the metal cations exhibit a distorted tetra­hedral coordination while the third exhibits a considerably distorted [5 + 1] octa­hedral coordination environment with one very long Co—O distance of 2.416 (3) Å. The former cations are bonded to four different phosphate anions, and the latter cation is bonded to four anions (one of which is bidentate) and one water mol­ecule, leading to a framework structure. Additional hydrogen bonds of the type O—H⋯O stabilize this arrangement. PMID:21200979

  9. Lanthanite-(Nd), Nd2(CO3)3·8H2O

    Science.gov (United States)

    Morrison, Shaunna M.; Andrade, Marcelo B.; Wenz, Michelle D.; Domanik, Kenneth J.; Downs, Robert T.

    2013-01-01

    Lanthanite-(Nd), ideally Nd2(CO3)3·8H2O [dineodymium(III) tricarbonate octa­hydrate], is a member of the lanthanite mineral group characterized by the general formula REE 2(CO3)3·8H2O, where REE is a 10-coordinated rare earth element. Based on single-crystal X-ray diffraction of a natural sample from Mitsukoshi, Hizen-cho, Karatsu City, Saga Prefecture, Japan, this study presents the first structure determination of lanthanite-(Nd). Its structure is very similar to that of other members of the lanthanite group. It is composed of infinite sheets made up of corner- and edge-sharing of two NdO10-polyhedra (both with site symmetry ..2) and two carbonate triangles (site symmetries ..2 and 1) parallel to the ab plane, and stacked perpendicular to c. These layers are linked to one another only through hydrogen bonding involving the water mol­ecules. PMID:23476479

  10. Co3(PO4)2·4H2O

    Science.gov (United States)

    Lee, Young Hoon; Clegg, Jack K.; Lindoy, Leonard F.; Lu, G. Q. Max; Park, Yu-Chul; Kim, Yang

    2008-01-01

    Single crystals of Co3(PO4)2·4H2O, tricobalt(II) bis­[ortho­phosphate(V)] tetra­hydrate, were obtained under hydro­thermal conditions. The title compound is isotypic with its zinc analogue Zn3(PO4)2·4H2O (mineral name hopeite) and contains two independent Co2+ cations. One Co2+ cation exhibits a slightly distorted tetra­hedral coordination, while the second, located on a mirror plane, has a distorted octa­hedral coordination environment. The tetra­hedrally coordinated Co2+ is bonded to four O atoms of four PO4 3− anions, whereas the six-coordinate Co2+ is cis-bonded to two phosphate groups and to four O atoms of four water mol­ecules (two of which are located on mirror planes), forming a framework structure. In addition, hydrogen bonds of the type O—H⋯O are present throughout the crystal structure. PMID:21200978

  11. Open chain or chemically bonded structure of H2O4: The hydroperoxyl radical dimer

    International Nuclear Information System (INIS)

    Fitzgerald, G.; Lee, T.J.; Schaefer, H.F. III; Bartlett, R.J.

    1985-01-01

    The straight chain isomer H--O--O--O--O--H of H 2 O 4 is of considerable current interest in combustion and atmospheric chemistry. Ab initio quantum mechanical methods have been used to study the geometrical structure, energetics, and vibrational frequencies of this species. Double zeta (DZ) and double zeta plus polarization (DZ+P) basis sets have been used in this theoretical study, the latter designated O(9s5p1d/4s2p1d), H(4s1p/2s1p). These basis sets have been employed in conjunction with self--consistent field (SCF)= and configuration interaction (CI) methods, including variationally up to 470 935 configurations. For the straight chain isomer, stationary points of symmetry C/sub 2h/, C/sub i/, and C 1 have been identified, and correspond to Hessian indices 3,1, and 0, respectively. The equilibrium geometry, having no elements of symmetry at all, is relatively unique. The highest level of theory (unlinked cluster corrected DZ+P CI) predicts the straight chain structure of H 2 O 4 to lie slightly lower in total energy than the cyclic two-hydrogen bond isomer