WorldWideScience

Sample records for monoxide photochemical oxidants

  1. 40 CFR 52.269 - Control strategy and regulations: Photochemical oxidants (hydrocarbons) and carbon monoxide.

    Science.gov (United States)

    2010-07-01

    ...: Photochemical oxidants (hydrocarbons) and carbon monoxide. 52.269 Section 52.269 Protection of Environment... PLANS California § 52.269 Control strategy and regulations: Photochemical oxidants (hydrocarbons) and... provide for attainment and maintenance of the national standards for photochemical oxidants...

  2. 40 CFR 52.1877 - Control strategy: Photochemical oxidants (hydrocarbons).

    Science.gov (United States)

    2010-07-01

    ... oxidants (hydrocarbons). 52.1877 Section 52.1877 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY....1877 Control strategy: Photochemical oxidants (hydrocarbons). (a) The requirements of Subpart G of this... national standard for photochemical oxidants (hydrocarbons) in the Metropolitan Cincinnati...

  3. Photochemical Transformation of Graphene Oxide in Sunlight

    Science.gov (United States)

    Graphene oxide (GO) is a graphene derivative that is more easily manufactured in large scale and used to synthesize reduced graphene oxide (rGO) with properties analogous to graphene. In this study, we investigate the photochemical fate of GO under sunlight conditions. The resu...

  4. Photochemical oxidation of dimethylsulfide in seawater

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    Dimethylsulfide (DMS) is generally thought to be lost from the surface oceans by evasion into the atmosphere as well as consumption by microbe. However, photochemical process might be important in the removal of DMS in the oceanic photic zone. A kinetic investigation into the photochemical oxidation of DMS in seawater was performed. The photo-oxidation rates of DMS were influenced by various factors including the medium, dissolved oxygen, photosensitizers, and heavy metal ions. The photo-oxidation rates of DMS were higher in seawater than in distilled water, presumably due to the effect of salinity existing in seawater. Three usual photosensitizers (humic acid, fulvic acid and anthroquinone), especially in the presence of oxygen, were able to enhance the photo-oxidation rate of DMS, with the fastest rate observed with anthroquinone. Photo-oxidation of DMS followed first order reaction kinetics with the rate constant ranging from 2.5×10-5 to 34.3×10-5 s-1. Quantitative analysis showed that approximately 32% of the photochemically removed DMS was converted to dimethylsulfoxide. One of the important findings was that the presence of Hg2+ could markedly accelerate the photo-oxidation rate of DMS in seawater. The mechanism of mercuric catalysis for DMS photolysis was suggested according to the way of CTTM (charge transfer to metal) of DMS-Hg2+ complex.

  5. Catalyst for Carbon Monoxide Oxidation

    Science.gov (United States)

    Davis, Patricia; Brown, Kenneth; VanNorman, John; Brown, David; Upchurch, Billy; Schryer, David; Miller, Irvin

    2010-01-01

    In many applications, it is highly desirable to operate a CO2 laser in a sealed condition, for in an open system the laser requires a continuous flow of laser gas to remove the dissociation products that occur in the discharge zone of the laser, in order to maintain a stable power output. This adds to the operating cost of the laser, and in airborne or space applications, it also adds to the weight penalty of the laser. In a sealed CO2 laser, a small amount of CO2 gas is decomposed in the electrical discharge zone into corresponding quantities of CO and O2. As the laser continues to operate, the concentration of CO2 decreases, while the concentrations of CO and O2 correspondingly increase. The increasing concentration of O2 reduces laser power, because O2 scavenges electrons in the electrical discharge, thereby causing arcing in the electric discharge and a loss of the energetic electrons required to boost CO2 molecules to lasing energy levels. As a result, laser power decreases rapidly. The primary object of this invention is to provide a catalyst that, by composition of matter alone, contains chemisorbed water within and upon its structure. Such bound moisture renders the catalyst highly active and very long-lived, such that only a small quantity of it needs to be used with a CO2 laser under ambient operating conditions. This object is achieved by a catalyst that consists essentially of about 1 to 40 percent by weight of one or more platinum group metals (Pt, Pd, Rh, Ir, Ru, Os, Pt being preferred); about 1 to 90 percent by weight of one or more oxides of reducible metals having multiple valence states (such as Sn, Ti, Mn, Cu, and Ce, with SnO2 being preferred); and about 1 to 90 percent by weight of a compound that can bind water to its structure (such as silica gel, calcium chloride, magnesium sulfate, hydrated alumina, and magnesium perchlorate, with silica gel being preferred). Especially beneficial results are obtained when platinum is present in the

  6. Photochemical oxidants: state of the science.

    Science.gov (United States)

    Kley, D; Kleinmann, M; Sanderman, H; Krupa, S

    1999-01-01

    Atmospheric photochemical processes resulting in the production of tropospheric ozone (O(3)) and other oxidants are described. The spatial and temporal variabilities in the occurrence of surface level oxidants and their relationships to air pollution meteorology are discussed. Models of photooxidant formation are reviewed in the context of control strategies and comparisons are provided of the air concentrations of O(3) at select geographic locations around the world. This overall oxidant (O(3)) climatology is coupled to human health and ecological effects. The discussion of the effects includes both acute and chronic responses, mechanisms of action, human epidemiological and plant population studies and briefly, efforts to establish cause-effect relationships through numerical modeling. A short synopsis is provided of the interactive effects of O(3) with other abiotic and biotic factors. The overall emphasis of the paper is on identifying the current uncertainties and gaps in our understanding of the state of the science and some suggestions as to how they may be addressed.

  7. Nitric oxide and carbon monoxide diffusing capacity of the lung

    NARCIS (Netherlands)

    Lee, I. van der

    2006-01-01

    The single breath diffusion capacity of the lung for carbon monoxide (DLCO) is measure for gas uptake by the lung, and consists of a membrane and a vascular component. Nitric oxide (NO) binds 400 times faster to hemoglobin than carbon monoxide, thus the uptake of NO by the blood is very large.

  8. Nitric oxide and carbon monoxide diffusing capacity of the lung

    NARCIS (Netherlands)

    Lee, I. van der

    2006-01-01

    The single breath diffusion capacity of the lung for carbon monoxide (DLCO) is measure for gas uptake by the lung, and consists of a membrane and a vascular component. Nitric oxide (NO) binds 400 times faster to hemoglobin than carbon monoxide, thus the uptake of NO by the blood is very large. There

  9. Photochemical oxidation: A solution for the mixed waste dilemma

    Energy Technology Data Exchange (ETDEWEB)

    Prellberg, J.W.; Thornton, L.M.; Cheuvront, D.A. [Vulcan Peroxidation Systems, Inc., Tucson, AZ (United States)] [and others

    1995-12-31

    Numerous technologies are available to remove organic contamination from water or wastewater. A variety of techniques also exist that are used to neutralize radioactive waste. However, few technologies can satisfactorily address the treatment of mixed organic/radioactive waste without creating unacceptable secondary waste products or resulting in extremely high treatment costs. An innovative solution to the mixed waste problem is on-site photochemical oxidation. Liquid-phase photochemical oxidation has a long- standing history of successful application to the destruction of organic compounds. By using photochemical oxidation, the organic contaminants are destroyed on-site leaving the water, with radionuclides, that can be reused or disposed of as appropriate. This technology offers advantages that include zero air emissions, no solid or liquid waste formation, and relatively low treatment cost. Discussion of the photochemical process will be described, and several case histories from recent design testing, including cost analyses for the resulting full-scale installations, will be presented as examples.

  10. Photochemical transformation of graphene oxide in sunlight (journal)

    Science.gov (United States)

    Graphene oxide (GO) is a graphene derivative that is more easily manufactured in large scale and used to synthesize reduced graphene oxide (rGO) with properties analogous to graphene. In this study, we investigate the photochemical fate of GO under sunlight conditions. The resu...

  11. Cobalt promoted copper manganese oxide catalysts for ambient temperature carbon monoxide oxidation.

    Science.gov (United States)

    Jones, Christopher; Taylor, Stuart H; Burrows, Andrew; Crudace, Mandy J; Kiely, Christopher J; Hutchings, Graham J

    2008-04-14

    Low levels of cobalt doping (1 wt%) of copper manganese oxide enhances its activity for carbon monoxide oxidation under ambient conditions and the doped catalyst can display higher activity than current commercial catalysts.

  12. Photochemical oxidation of halocarbons in the troposphere

    Energy Technology Data Exchange (ETDEWEB)

    Cox, R.A. (Atomic Energy Research Establishment, Harwell, Eng.); Derwent, R.G.; Eggleton, A.E.J.; Lovelock, J.E.

    1976-01-01

    Measurements of the reactivity of hydroxyl radicals with some simple halocarbons are reported, together with some new measurements of the air concentration of halocarbons in the N and S hemispheres. The OH reactivities are used to derive life-times of the halocarbons with respect to photo-oxidation in the troposphere. It is found that the chlorohydrocarbons containing H atoms are moderately reactive with lifetimes of 1 y or less but the fully halogenated compounds carbon tetrachloride and Freons 11 and 12 are essentially inert towards photo-oxidation. The air concentration and reactivity data are combined to provide an estimate of the magnitude of the tropospheric sink for the halocarbons due to oxidation by OH radicals. For some of the more reactive halocarbons this sink exceeds the estimated anthropogenic emissions and an additional, possibly natural, source is indicated.

  13. Oxidation of carbon monoxide by perferrylmyoglobin

    DEFF Research Database (Denmark)

    Libardi, Silvia H; Skibsted, Leif Horsfelt; Cardoso, Daniel R

    2014-01-01

    Perferrylmyoglobin is found to oxidize CO in aerobic aqueous solution to CO2. Tryptophan hydroperoxide in the presence of tetra(4-sulfonatophenyl)-porphyrinate-iron(III) or simple iron(II)/(III) salts shows similar reactivity against CO. The oxidation of CO is for tryptophan hydroperoxide conclud...

  14. Evidence for significant photochemical production of carbon monoxide by particles in coastal and oligotrophic marine waters

    Science.gov (United States)

    Xie, Huixiang; Zafiriou, Oliver C.

    2009-12-01

    Carbon monoxide (CO) photoproduction from particulate and chromophoric dissolved organic matter (CDOM) was determined in seawater from open-ocean and coastal areas. In confirmatory tests, poisoned or non-poisoned filtered and unfiltered blue-water samples, were exposed to sunlight. CO photoproduction was 21-42% higher in the unfiltered than in the filtered samples. In a more thorough study utilizing concentrated particles prepared by 0.2-μm cross-flow filtration, samples containing varying levels of particles were irradiated under simulated solar radiation. Their CO photoproduction rates increased linearly with particle concentration factor. Particulate CO production was 11-35% of CDOM-based CO production. On an absorbed-photons basis, the former was 30-108% more efficient than the latter. This study suggests that in both coastal and blue waters these new-found particulate photoprocesses are of similar biogeochemical importance to the well-known CDOM photoproduction term.

  15. Kinetics study on photochemical oxidation of polyacrylamide by ozone combined with hydrogen peroxide and ultraviolet radiation

    Institute of Scientific and Technical Information of China (English)

    REN Guang-meng; SUN De-zhi; CHUNG Jong Shik

    2006-01-01

    An investigation on the process of ozone combined with hydrogen peroxide and ultraviolet radiation has been carried out in order to establish the kinetics for photochemical oxidation of polyacrylamide (PAM) in aqueous solution. Effects of operating parameters, including initial PAM concentration, dosages of ozone and hydrogen peroxide, UV radiation and pH value on the photochemical oxidation of PAM, have been studied. There was an increase in photochemical oxidation rate of PAM with increasing of dosages of O3, H2O2 and ultraviolet radiation. Upon increasing of the initial PAM concentration, the photochemical oxidation rate of PAM decreased. Slight effect of pH value on the photochemical oxidation rate of PAM was observed in the experiments. The kinetics equation for the photochemical oxidation of PAM by the system has been established.

  16. Photochemical oxidation of persistent cyanide-related compounds

    Science.gov (United States)

    Budaev, S. L.; Batoeva, A. A.; Khandarkhaeva, M. S.; Aseev, D. G.

    2017-03-01

    Kinetic regularities of the photolysis of thiocyanate solutions using of mono- and polychromatic UV radiation sources with different spectral ranges are studied. Comparative experiments aimed at investigating the role of photochemical action during the oxidation of thiocyanates with persulfates and additional catalytic activation with iron(III) ions are performed. The rate of conversion and the initial rate of thiocyanate oxidation are found to change in the order UV < UV/S2O 8 2- < S2O 8 2- /Fe3+ < UV/S2O 8 2- /Fe3+. A synergistic effect is detected when using the combined catalytic method for the destruction of thiocyanates by the UV/S2O 8 2- /Fe3+ oxidation system. This effect is due to the formation of reactive oxygen species, as a result of both the decomposition of persulfate and the reduction of inactive Fe3+ intermediates into Fe3+.

  17. Anoxic photochemical oxidation of siderite generates molecular hydrogen and iron oxides.

    Science.gov (United States)

    Kim, J Dongun; Yee, Nathan; Nanda, Vikas; Falkowski, Paul G

    2013-06-18

    Photochemical reactions of minerals are underappreciated processes that can make or break chemical bonds. We report the photooxidation of siderite (FeCO3) by UV radiation to produce hydrogen gas and iron oxides via a two-photon reaction. The calculated quantum yield for the reaction suggests photooxidation of siderite would have been a significant source of molecular hydrogen for the first half of Earth's history. Further, experimental results indicate this abiotic, photochemical process may have led to the formation of iron oxides under anoxic conditions. The reaction would have continued through the Archean to at least the early phases of the Great Oxidation Event, and provided a mechanism for oxidizing the atmosphere through the loss of hydrogen to space, while simultaneously providing a key reductant for microbial metabolism. We propose that the photochemistry of Earth-abundant minerals with wide band gaps would have potentially played a critical role in shaping the biogeochemical evolution of early Earth.

  18. Tsukamurella carboxydivorans sp. nov., a carbon monoxide-oxidizing actinomycete.

    Science.gov (United States)

    Park, Sae W; Kim, Sung M; Park, Sang T; Kim, Young M

    2009-06-01

    A Gram-positive, slightly acid-alcohol-fast, carbon monoxide-oxidizing bacterium, strain Y2(T), was isolated from a soil sample collected from a roadside in Seoul, Korea. On the basis of 16S rRNA gene sequence comparative analyses, strain Y2(T) was shown to belong to the genus Tsukamurella and was most closely related to Tsukamurella tyrosinosolvens DSM 44234(T) (GenBank accession no. AY238514; 99.8 %). The predominant fatty acids were C(18 : 1)omega9c and C(16 : 0). The cell-wall peptidoglycan of strain Y2(T) contained meso-diaminopimelic acid as the diagnostic diamino acid. Strain Y2(T) contained galactose and arabinose as the whole cell sugars. The DNA G+C content was 77 mol%. The DNA-DNA relatedness value between strain Y2(T) and T. tyrosinosolvens DSM 44234(T) was 62.7 %. Based on the combination of the carbon source utilization pattern, fatty acid profile, cell-wall chemotype, DNA G+C content and DNA-DNA hybridization experiments, it is proposed that strain Y2(T) (=KCCM 42885(T)=JCM 15482(T)) represents the type strain of a novel species, Tsukamurella carboxydivorans sp. nov.

  19. Kinetic and photochemical data for atmospheric chemistry reactions of the nitrogen oxides

    Science.gov (United States)

    Hampson, R. F., Jr.

    1980-01-01

    Data sheets for thermal and photochemical reactions of importance in the atmospheric chemistry of the nitrogen oxides are presented. For each reaction the available experimental data are summarized and critically evaluated, and a preferred value of the rate coefficient is given. The selection of the preferred value is discussed and an estimate of its accuracy is given. For the photochemical process, the data are summarized, and preferred for the photoabsorption cross section and primary quantum yields are given.

  20. 40 CFR 52.229 - Control strategy and regulations: Photochemical oxidants (hydrocarbons), Metropolitan Los Angeles...

    Science.gov (United States)

    2010-07-01

    ...: Photochemical oxidants (hydrocarbons), Metropolitan Los Angeles Intrastate Region. 52.229 Section 52.229... oxidants (hydrocarbons), Metropolitan Los Angeles Intrastate Region. (a) (b) The following rules are... and approved for the SIP, remain federally enforceable: (1) Los Angeles County APCD, Regulation IV...

  1. Electrochemical oxidation of carbon monoxide: from platinum single crystals to low temperature fuel cells catalysts. Part I: Carbon monoxide oxidation onto low index platinum single crystals

    Directory of Open Access Journals (Sweden)

    PHILIP N. ROSS JR

    2001-12-01

    Full Text Available The electrochemical oxidation of carbon monoxide and the interfacial structure of the CO adlayer (COads on platinum low index single crystals, Pt(111, Pt(100 and two reconstruction of Pt(110, were examined using the rotation disk electrode method in combination with the in situ surface X-ray diffraction scattering technique. The mechanism of CO oxidation is discussed on the basis of the findings that, depending on the potential, two energetic states of COads exist on the platinum surfaces. Thus, at lower potentials, weakly bonded states (COads,w and at higher potentials strongly bonded states (COads,s are formed. The mechanism of the oxidation of hydrogen-carbon monoxide mixtures is also proposed.

  2. Investigation of the Carbon Monoxide Gas Sensing Characteristics of Tin Oxide Mixed Cerium Oxide Thin Films

    Directory of Open Access Journals (Sweden)

    Muhammad B. Haider

    2012-02-01

    Full Text Available Thin films of tin oxide mixed cerium oxide were grown on unheated substrates by physical vapor deposition. The films were annealed in air at 500 °C for two hours, and were characterized using X-ray photoelectron spectroscopy, atomic force microscopy and optical spectrophotometry. X-ray photoelectron spectroscopy and atomic force microscopy results reveal that the films were highly porous and porosity of our films was found to be in the range of 11.6–21.7%. The films were investigated for the detection of carbon monoxide, and were found to be highly sensitive. We found that 430 °C was the optimum operating temperature for sensing CO gas at concentrations as low as 5 ppm. Our sensors exhibited fast response and recovery times of 26 s and 30 s, respectively.

  3. An infrared spectroscopic study of the adsorption of carbon monoxide on silica-supported copper oxide

    NARCIS (Netherlands)

    Jong, K.P. de; Geus, John W.; Joziasse, J.

    1980-01-01

    Adsorption of carbon monoxide at room temperature (0.1–50 Torr) on silica-supported copper oxide was studied by infrared spectroscopy. Catalysts were prepared by deposition-precipitation or impregnation. After calcination two types of adsorbed CO were identified showing absorption bands at 2136 ± 3

  4. Carbon monoxide oxidation using Zn-Cu-Ti hydrotalcite-derived catalysts

    Indian Academy of Sciences (India)

    O Saber; T Zaki

    2014-07-01

    Multioxide catalysts of zinc, copper and titanium with different ratios obtained from layered double hydroxide (LDH) precursors were used in the oxidation of carbon monoxide. The catalysts were characterized by energy-dispersive X-ray spectrometry, X-ray diffraction, thermal analyses (TG, DTG and DTA) and scanning electron microscopy. X-ray diffraction showed different phases of double hydroxide structures. On increasing the percentage of zinc, hydrotalcite structure became the main phase in these samples. SEM images confirmed the presence of layered double hydroxide as plate-like structure. Experimental results indicated a sharp increase in the catalytic activities of the calcined samples towards the oxidation of carbon monoxide at temperatures in the range of 225-275°C. High conversion of carbon monoxide (90 ∼ 95%) was achieved at reaction temperature of 275°C by samples having ZnTiO3 as a main phase. These results suggested that hydrotalcite structure of Zn-Ti has a positive catalytic effect towards carbon monoxide oxidation.

  5. Surface structure and relaxation during the oxidation of carbon monoxide on Pt Pd bimetallic surfaces

    Science.gov (United States)

    Lucas, C. A.; Markovic, N. M.; Ball, M.; Stamenkovic, V.; Climent, V.; Ross, P. N.

    2001-05-01

    The atomic structure and surface relaxation of Pd monolayer on Pt(1 1 1) has been studied by surface X-ray scattering, in an aqueous environment under electrostatic potential control, during the adsorption and oxidation of carbon monoxide. The results show that the Pd-Pt layer spacing contracts at the onset of CO oxidation before the Pd adlayer forms an oxide structure that is incommensurate with the Pt lattice. Both the oxide formation and the lattice contraction are fully reversible over many cycles of the applied electrode potential.

  6. Gold catalysts supported on nanosized iron oxide for low-temperature oxidation of carbon monoxide and formaldehyde

    Science.gov (United States)

    Tang, Zheng; Zhang, Weidong; Li, Yi; Huang, Zuming; Guo, Huishan; Wu, Feng; Li, Jinjun

    2016-02-01

    This study aimed to optimize synthesis of gold catalyst supported on nanosized iron oxide and to evaluate the activity in oxidation of carbon monoxide and formaldehyde. Nanosized iron oxide was prepared from a colloidal dispersion of hydrous iron oxide through a dispersion-precipitation method. Gold was adsorbed onto nanosized iron oxide under self-generated basic conditions. Characterization results indicate that the iron oxide consisted of hematite/maghemite composite with primary particle sizes of 6-8 nm. Gold was highly dispersed on the surface of the support. The catalysts showed good activity in the oxidation of airborne carbon monoxide and formaldehyde. The optimal pH for their synthesis was ∼7. The catalytic performance could be enhanced by extending the adsorption time of gold species on the support within 21 h. The optimized catalyst was capable of achieving complete oxidation of 1% carbon monoxide at -20 °C and 33% conversion of 450 ppm formaldehyde at ambient temperature. The catalyst may be applicable to indoor air purification.

  7. Vertical observation of molecular hydrogen and carbon monoxide: Implication for non-photochemical H2 production at ocean surface and subsurface

    Science.gov (United States)

    Kawagucci, S.; Narita, T.; Obata, H.; Ogawa, H.; Gamo, T.

    2009-12-01

    Biological nitrogen fixation is a key metabolism controlling marine N-cycling and also known as a main H2 source. Recently, it was proposed that a monitoring of surface H2 concentration could be used quickly to figure out the spatial extent of biological nitrogen fixation activity without onboard incubation required for currently used methods for detecting the activity. However, H2 behavior in ocean water was still unresolved. This study carried out vertical observation of H2 and CO concentrations in south of Japan, western North Pacific. Because carbon monoxide, CO, in seawater has no relation with nitrogen fixation metabolism and is produced dominantly by the photochemical reaction, which is an altanative H2 source, simultaneous observation and comparison of H2 and CO concentration is helpful to investigate H2 behavior in ocean water. Reductive gases in seawater were observed during the R/V Tansei-maru KT-08-14 cruise by using a wired CTD-CMS (CTD-carousel multiple sampling) system to conduct vertical sampling (at most 200 m depth) and by using a plastic bucket for sampling surface seawater. The sample in the Niskin-X bottle was directed to the bottom of a 120 mL brown-colored glass vial allowed to overflow by 2 volumes before the tube was slowly withdrawn. After the addition of 0.5 mL HgCl2-saturated solution for poisoning, the PTFE-lined butyl-gum septum was used to cap the vials. Molecular hydrogen (H2) and carbon monoxide (CO) were analyzed at an onboard laboratory within 6 hours after subsampling. 20 mL of sample water was substituted by 20 mL of H2- and CO-free air using a gas-tight syringe; then the vial was put on an automatic shaker and shaken upside down for 6 minutes to achieve a complete equilibrium between the dissolved and head space gases in the vial. The equilibrated headspace was taken by another gas-tight syringe and then injected into a gas chromatograph equipped with a trace reduced gas detector. Vertical distribution of dissolved H2 and CO

  8. Selective oxidation of carbon monoxide in the presence of butane and maleic anhydride

    Energy Technology Data Exchange (ETDEWEB)

    Corbin, D.R.; Bonifaz, C. (DuPont Company, Wilmington, DE (United States))

    1994-03-01

    The selective oxidation of carbon monoxide in the presence of butane and maleic anhydride has been studied over platinum- and palladium-containing zeolites as well as palladium-on-silica (Pd/SiO[sub 2]) catalysts. The results show that although a zeolite support is needed in many systems to effect a kinetic control to improve selectivity, thermodynamic control using Pd([approximately]2-4 ppm)/SiO[sub 2] is sufficient to give the desired selectivities in this system. In addition, a palladium-containing vanadium-phosphate catalyst was prepared that showed complete oxidation of carbon monoxide, conversion of butane to maleic anhydride, and no observable decomposition of the maleic anhydride. 14 refs., 4 tabs.

  9. Sunlight-induced photochemical decay of oxidants in natural waters: implications in ballast water treatment.

    Science.gov (United States)

    Cooper, William J; Jones, Adam C; Whitehead, Robert F; Zika, Rod G

    2007-05-15

    The transport and discharge of ship ballast water has been recognized as a major vector for the introduction of invasive species. Chemical oxidants, long used in drinking water and wastewater treatment, are alternative treatment methods for the control of invasive species currently being tested for use on ships. One concern when a ballasted vessel arrives in port is the adverse effects of residual oxidant in the treated water. The most common oxidants include chlorine (HOCl/OCl-), bromine (HOBr/OBr-), ozone (03), hydrogen peroxide (H2O2), chlorine dioxide (ClO2), and monochloramine (NH2Cl). The present study was undertaken to evaluate the sunlight-mediated photochemical decomposition of these oxidants. Sunlight photodecomposition was measured at various pH using either distilled water or oligotrophic Gulf Stream water for specific oxidants. For selected oxidants, quantum yields at specific wavelengths were obtained. An environmental photochemical model, GCSOLAR, also provided predictions of the fate (sunlight photolysis half-lives) of HOCI/OCl-, HOBr/OBr-, ClO2, and NH2Cl for two different seasons at latitude 40 degrees and in water with two different concentrations of chromophoric dissolved organic matter. These data are useful in assessing the environmental fate of ballast water treatment oxidants if they were to be discharged in port.

  10. Resveratrol Induces Hepatic Mitochondrial Biogenesis Through the Sequential Activation of Nitric Oxide and Carbon Monoxide Production

    OpenAIRE

    Kim, Seul-Ki; Joe, Yeonsoo; Min ZHENG; Kim, Hyo Jeong; Yu, Jae-Kyoung; Cho, Gyeong Jae; Chang, Ki Churl; Kim, Hyoung Kyu; Han, Jin; Ryter, Stefan W.; Chung, Hun Taeg

    2014-01-01

    Aims: Nitric oxide (NO) can induce mitochondrial biogenesis in cultured cells, through increased guanosine 3′,5′-monophosphate (cGMP), and activation of peroxisome proliferator-activated receptor gamma coactivator-1α (PGC-1α). We sought to determine the role of NO, heme oxygenase-1 (HO-1), and its reaction product (carbon monoxide [CO]) in the induction of mitochondrial biogenesis by the natural antioxidant resveratrol. Results: S-nitroso-N-acetylpenicillamine (SNAP), an NO donor, induced ...

  11. Carbon monoxide-induced reduction and healing of graphene oxide

    NARCIS (Netherlands)

    Narayanan, B.; Weeks, S. L.; Jariwala, B. N.; Macco, B.; Weber, J.; Rathi, S. J.; M. C. M. van de Sanden,; Sutter, P.; Agarwal, S.; Ciobanu, C. V.

    2013-01-01

    Graphene oxide holds promise as a carbon-based nanomaterial that can be produced inexpensively in large quantities. However, its structural and electrical properties remain far from those of the graphene sheets obtained by mechanical exfoliation or by chemical vapor deposition unless efficient reduc

  12. Carbon monoxide-induced reduction and healing of graphene oxide

    NARCIS (Netherlands)

    Narayanan, B.; Weeks, S. L.; Jariwala, B. N.; Macco, B.; Weber, J.; Rathi, S. J.; M. C. M. van de Sanden,; Sutter, P.; Agarwal, S.; Ciobanu, C. V.

    2013-01-01

    Graphene oxide holds promise as a carbon-based nanomaterial that can be produced inexpensively in large quantities. However, its structural and electrical properties remain far from those of the graphene sheets obtained by mechanical exfoliation or by chemical vapor deposition unless efficient reduc

  13. Interaction and reactivity of nitric oxide and carbon monoxide on ruthenium surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Quick, E.E.

    1980-03-01

    A multifaceted investigation of the reduction of nitric oxide by carbon monoxide using a ruthenium (102) single crystal catalyst in the pressure range 10/sup -3/ to 10 Torr and temperature range of 300 to 475/sup 0/C has been undertaken. Kinetic and isotopic results indicate that the reaction products CO/sub 2/ and N/sub 2/ were produced via two reaction mechanisms. Using a reducing gas mixture (low P/sub NO//P/sub CO/ ratio) a two site mechanism was operative involving NO dissociation. The carbon monoxide kinetic order varied from +1 to -3 and the nitric oxide order varied from +1 to 0. The catalyst under these conditions was determined to be metallic ruthenium with oxygen bonded within the first surface layer. The oxygen was unreactive and formed a (1 x 3)-0 LEED pattern. Under oxidizing conditions (high P/sub NO//P/sub CO/ ratio) the catalyst was ruthenium dioxide and the functional mechanism under these reaction conditions yielded a nitric oxide order of +2 to -4. Inclusion of a site poisoning mechanism under reducing conditions and an RuO/sub 2/ growth mechanism involving ruthenium cation transfer under oxidizing conditions into the kinetic rate laws led to an overall rate law which could be fit to the carbon monoxide and nitric oxide order plots. Using isotopically oxygen labelled reactants, it was observed that the three possible isotopes of carbon dioxide were produced. A ..gamma..-CO surface species is postulated as an intermediate in the exchange process. The reaction was observed to be initially surface structure insensitive and the reaction kinetics were derived using a Langmuir-Hinshelwood formalism.

  14. European scale modeling of sulfur, oxidized nitrogen and photochemical oxidants. Model development and evaluation for the 1994 growing season

    Energy Technology Data Exchange (ETDEWEB)

    Langner, J.; Bergstroem, R. [Swedish Meteorological and Hydrological Inst., Norrkoeping (Sweden); Pleijel, K. [Swedish Environmental Research Inst., Goeteborg (Sweden)

    1998-09-01

    A chemical mechanism, including the relevant reactions leading to the production of ozone and other photochemical oxidants, has been implemented in the MATCH regional tracer transport/chemistry/deposition model. The aim has been to develop a model platform that can be used as a basis for a range of regional scale studies involving atmospheric chemistry, including assessment of the importance of different sources of pollutants to the levels of photochemical oxidants and air pollutant forecasting. Meteorological input data to the model were taken from archived output from the operational version of HIRLAM at SMHI. Evaluation of model calculations over Europe for a six month period in 1994 for a range of chemical components show good results considering known sources of error and uncertainties in input data and model formulation. With limited further work the system is sufficiently good to be applied for scenario studies and for regional scale air pollutant forecasts 42 refs, 24 figs, 17 tabs

  15. Carbon monoxide and nitric oxide from biofuel fires in Kenya

    Energy Technology Data Exchange (ETDEWEB)

    Kituyi, E.; Wandiga, S.O.; Jumba, I.O. [University of Nairobi (Kenya). Dept. of Chemistry; Marufu, L.; Andreae, M.O.; Helas, G. [Max Planck Inst. for Chemistry, Mainz (Germany). Dept. of Biochemistry

    2001-09-01

    Emission ratios (ER) of CO and NO relative to CO{sub 2} are reported from real time emission measurements on biofuel fires in Kenya. The experiments were based on available fuels burning in local popular traditional and improved stoves. The mean dCO/dCO{sub 2} ratios were 71, 79 and 74 mmol mol{sup -1} for firewood, charcoal and agricultural residues, respectively, while the corresponding mean dNO/dCO{sub 2} ratios for these fuels, in the same order, were 1.8, 2 and 2.2 mmol mol{sup -1}, respectively. Whereas stove design characteristics largely influenced the dCO/dCO{sub 2} ratios, the fuel nitrogen content was the major factor determining the dNO/dCO{sub 2} ratios. The dCO/dCO{sub 2} ratio for fuel derived NO is not affected by fire temperature but linearly depend on the fuel nitrogen content. Other important fuel parameters that influenced the observed emission ratio patterns include fuel moisture content, size and volatile matter content in the case of charcoal. In comparison to savanna and forest fires, biofuel fires tend to favour formation of reduced or partially oxidized compounds. It is clear that a change in energy preference up the ''energy ladder'' leads to a reduction in the CO ER, and important results for emission mitigation policy design. (author)

  16. Selective catalytic reduction of sulfur dioxide by carbon monoxide over iron oxide supported on activated carbon

    OpenAIRE

    2014-01-01

    The selective reduction of sulfur dioxide with carbon monoxide to elemental sulfur was studied over AC-supported transition-metal oxide catalysts. According to the study, Fe2O3/AC was the most active catalyst among the 4 AC-supported catalysts tested. By using Fe2O3/AC, the best catalyst, when the feed conditions were properly optimized (CO/SO2 molar ratio = 2:1; sulfidation temperature, 400 °C; Fe content, 20 wt%; GHSV = 7000 mL g-1 h-1), 95.43% sulfur dioxide conversion and 86.59% sulfur yi...

  17. Investigations on the necrotic injury to Taro Leaf by photochemical oxidants

    Energy Technology Data Exchange (ETDEWEB)

    Matsuoka, Y.; Takasaki, T.; Morikawa, M.; Matsumaru, T.; Shiratori, K.; Omichi, S.; Yoda, H.

    1975-03-01

    In August of 1969, taro, Colocasia antiquorum SCHOTT., planted in Ichihara city and neighboring towns in chiba prefecture, was observed to be suddenly damaged. The injury appeared as reddish-brown necrotic spots on interveinal mesophyll along the veins. Some injured leaves died back within few days. In order to resolve the reason for singular leaf injury, field surveys were made everywhere leaf injury occurred. The cause of taro leaf injury was determined to be as follows and attributed to air pollution. 1) Two plant growth chambers were prepared for this examinations. One was equipped with activated carbon and manganese dioxide filters for the purpose of removing air pollutants such as photochemical oxidants and sulfur dioxide. The other was without any filter. 2) When was planted taro in the filtered chamber, the injury was completely suppressed. In the filterless chamber the injury occurred many times throughout summer. 3) It was found that the air was sometimes polluted by photochemical oxidants and pollutants achieved more than 10 or 20 pphm in maximum concentration in the filterless chamber. Taro leaf injury developed immediately after occurrance of photochemical air pollutants. 4) At that time tobacco, Bel W3 which had been planted together with taro in filterless chamber, was severly injured. 5) Histological observation was carried out on cross sections of injured leaves. Their palisade cells and tissues were damaged and brown pigment sometimes accumulated in affected tissue, but epidermis and spongy tissues remained normal. 6) Ozone fumigation was examined on taro leaves with 30 pphm in concentration for 3 hours. Immediately after the fumigation water soaked spots developed on their leaves and turned to the chlorotic spots after 1 or 2 days. Most of chlorotic spots developed on interveinal mesophyll along the vein.

  18. Hydrogen Oxidation on Gas Diffusion Electrodes for Phosphoric Acid Fuel Cells in the Presence of Carbon Monoxide and Oxygen

    DEFF Research Database (Denmark)

    Gang, Xiao; Li, Qingfeng; Hjuler, Hans Aage

    1995-01-01

    Hydrogen oxidation has been studied on a carbon-supported platinum gas diffusion electrode in a phosphoric acidelectrolyte in the presence of carbon monoxide and oxygen in the feed gas. The poisoning effect of carbon monoxide presentin the feed gas was measured in the temperature range from 80...... to 150°C. It was found that throughout the temperaturerange, the potential loss due to the CO poisoning can be reduced to a great extent by the injection of small amounts ofgaseous oxygen into the hydrogen gas containing carbon monoxide. By adding 5 volume percent (v/o) oxygen, an almost......CO-free performance can be obtained for carbon monoxide concentrations up to 0.5 v/o CO at 130°C, 0.2 v/o CO at 100°C,and 0.1 v/o CO at 80°C, respectively....

  19. Review of photochemical reaction constants of organic micropollutants required for UV advanced oxidation processes in water.

    Science.gov (United States)

    Wols, B A; Hofman-Caris, C H M

    2012-06-01

    Emerging organic contaminants (pharmaceutical compounds, personal care products, pesticides, hormones, surfactants, fire retardants, fuel additives etc.) are increasingly found in water sources and therefore need to be controlled by water treatment technology. UV advanced oxidation technologies are often used as an effective barrier against organic contaminants. The combined operation of direct photolysis and reaction with hydroxyl radicals ensures good results for a wide range of contaminants. In this review, an overview is provided of the photochemical reaction parameters (quantum yield, molar absorption, OH radical reaction rate constant) of more than 100 organic micropollutants. These parameters allow for a prediction of organic contaminant removal by UV advanced oxidation systems. An example of contaminant degradation is elaborated for a simplified UV/H(2)O(2) system.

  20. Total OH reactivity study from VOC photochemical oxidation in the SAPHIR chamber

    Science.gov (United States)

    Yu, Z.; Tillmann, R.; Hohaus, T.; Fuchs, H.; Novelli, A.; Wegener, R.; Kaminski, M.; Schmitt, S. H.; Wahner, A.; Kiendler-Scharr, A.

    2015-12-01

    It is well known that hydroxyl radicals (OH) act as a dominant reactive species in the degradation of VOCs in the atmosphere. In recent field studies, directly measured total OH reactivity often showed poor agreement with OH reactivity calculated from VOC measurements (e.g. Nölscher et al., 2013; Lu et al., 2012a). This "missing OH reactivity" is attributed to unaccounted biogenic VOC emissions and/or oxidation products. The comparison of total OH reactivity being directly measured and calculated from single component measurements of VOCs and their oxidation products gives us a further understanding on the source of unmeasured reactive species in the atmosphere. This allows also the determination of the magnitude of the contribution of primary VOC emissions and their oxidation products to the missing OH reactivity. A series of experiments was carried out in the atmosphere simulation chamber SAPHIR in Jülich, Germany, to explore in detail the photochemical degradation of VOCs (isoprene, ß-pinene, limonene, and D6-benzene) by OH. The total OH reactivity was determined from the measurement of VOCs and their oxidation products by a Proton Transfer Reaction Time of Flight Mass Spectrometer (PTR-TOF-MS) with a GC/MS/FID system, and directly measured by a laser-induced fluorescence (LIF) at the same time. The comparison between these two total OH reactivity measurements showed an increase of missing OH reactivity in the presence of oxidation products of VOCs, indicating a strong contribution to missing OH reactivity from uncharacterized oxidation products.

  1. Reduction of nitric oxide with carbon monoxide on the Al-Mo(110) surface alloy

    Science.gov (United States)

    Grigorkina, G. S.; Tvauri, I. V.; Kaloeva, A. G.; Burdzieva, O. G.; Sekiba, D.; Ogura, S.; Fukutani, K.; Magkoev, T. T.

    2016-05-01

    Coadsorption and reaction of carbon monoxide (CO) and nitric oxide (NO) on Al-Mo(110) surface alloy have been studied by means of Auger electron, reflection-absorption infrared and temperature programmed desorption spectroscopies (AES, RAIRS, TPD), low energy electron diffraction (LEED) and work function measurements. The Al-Mo(110) surface alloy was obtained by thermal annealing at 800 K of aluminum film deposited on Mo(110) held at room temperature. Upon annealing Al penetrates the surface, most likely forming stoichiometric hexagonal surface monolayer of the compound Al2Mo. The NO and CO adsorb molecularly on this alloy surface at 200 K, unlike totally dissociative adsorption on bare Mo(110) and Al(111) film. Adsorption of CO on NO precovered Al-Mo(110) substrate dramatically affects the state of NO molecules, most probably displacing them to higher-coordinated sites with their simultaneous tilting to the surface plane. Heating to about room temperature (320 K) causes reduction of nitric oxide with carbon monoxide, yielding CO2, and substrate nitridation. This behavior can be associated with the surface reconstruction providing additional Al/Mo interface reaction sites and change of the d-band upon alloying.

  2. Carbon monoxide gas sensing using zinc oxide film deposited by spray pyrolysis

    Science.gov (United States)

    Leano, J. M. G.; Villapando, J. M. L. A.; Balaaldia, A. E.; Gianan, G.; Manalo, F. K. B.; Florido, E. A.

    2017-05-01

    This study was aimed to determine the carbon monoxide (CO) gas sensing ability of zinc oxide (ZnO) film fabricated by spray pyrolysis on glass substrate heated at 3000C using 0.2 M zinc acetate precursor solution. The temperature of the precursor solution was maintained at room temperature. Carbon monoxide gas was synthesized by mixing the required amount of formic acid and excess sulfuric acid in the ratio of 1:6 to produce CO gas concentrations of 100, 200, 300, 400, and 500 parts per million (ppm) v/v. There were five trials for each concentration. The films produced exhibited good sensor characteristics such as high linearity in current voltage relationship and voltage response versus concentration. Electrical characterization using the four-point probe showed a linear relationship between current and voltage with resistivity of 0.49 ohm-cm and R2 value of 0.994 The zinc oxide film exhibited a sensitivity of 0.19 Volt per 100 ppm of CO gas and linearity R2 value of 0.993.

  3. The Photochemical Oxidation of Siderite That Drove Hydrogen Based Microbial Redox Reactions in The Archean Biosphere

    Science.gov (United States)

    Kim, J. D.; Yee, N.; Falkowski, P. G.

    2012-12-01

    Hydrogen is the most abundant element in the universe and molecular hydrogen (H2) is a rich source of electron in a mildly reducing environment for microbial redox reactions, such as anoxygenic photosynthesis and methanogenesis. Subaerial volcanoes, ocean crust serpentinization and mid-ocean ridge volcanoes have been believed to be the major source of the hydrogen flux to the atmosphere. Although ferrous ion (Fe2+) photooxidation has been proposed as an alternative mechanism by which hydrogen gas was produced, ferruginous water in contact with a CO2-bearing atmosphere is supersaturated with respect to FeCO3 (siderite), thus the precipitation of siderite would have been thermodynamically favored in the Archean environment. Siderite is the critical mineral component of the oldest fossilized microbial mat. It has also been inferred as a component of chemical sedimentary protolith in the >3750 Ma Nuvvuagittuq supracrustal belt, Canada and the presence of siderite in the protolith suggests the occurrence of siderite extends to Hadean time. Analyses of photooxidation of siderite suggest a significant flux of hydrogen in the early atmosphere. Our estimate of the hydrogen production rate under Archean solar flux is approximately 50 times greater than the estimated hydrogen production rate by the volcanic activity based on a previous report (Tian et al. Science 2005). Our analyses on siderite photooxidation also suggest a mechanism by which banded iron formation (BIF) was formed. The photooxidation transforms siderite to magnetite/maghemite (spinnel iron oxide), while oxygenic oxidation of siderite leads to goethite, and subsequently to hematite (Fe3+2O3) upon dehydration. We will discuss the photochemical reaction, which was once one of the most ubiquitous photochemical reactions before the rise of oxygen in the atmosphere. Photooxidation of siderite over time by UV light From left to right: UV oxidized siderite, pristine siderite, oxidized siderite by oxygen

  4. A Review on Preferential Oxidation of Carbon Monoxide in Hydrogen Rich Gases

    Directory of Open Access Journals (Sweden)

    A. Mishra

    2011-05-01

    Full Text Available In this review, recent works on the preferential oxidation of carbon monoxide in hydrogen rich gases for fuel cell applications are summarized. H2 is used as a fuel for polymer-electrolyte membrane fuel cell (PEMFC. It is produced by reforming of natural gas or liquid fuels followed by water gas shift reaction. The produced gas consists of H2, CO, and CO2. In which CO content is around 1%, which is highly poisonous for the Pt anode of the PEMFC so that further removal of CO is needed. Catalytic preferential oxidation of CO (CO-PROX is one of the most suitable methods of purification of H2 because of high CO conversion rate at low temperature range, which is preferable for PEMFC operating conditions. Catalysts used for COPROX are mainly noble metal based; gold based and base metal oxide catalysts among them Copper-Ceria based catalysts are the most appropriate due to its low cost, easy availability and result obtained by these catalysts are comparable with the conventional noble metal catalysts. Copyright © 2011 BCREC UNDIP. All rights reserved(Received: 22nd October 2010, Revised: 12nd January 2011, Accepted: 19th January 2011[How to Cite: A. Mishra, R. Prasad. (2011. A Review on Preferential Oxidation of Carbon Monoxide in Hydrogen Rich Gases. Bulletin of Chemical Reaction Engineering & Catalysis, 6 (1: 1-14. doi:10.9767/bcrec.6.1.191.1-14][How to Link / DOI: http://dx.doi.org/10.9767/bcrec.6.1.191.1-14 || or local:  http://ejournal.undip.ac.id/index.php/bcrec/article/view/191] | View in 

  5. Evaluation of simulated photochemical partitioning of oxidized nitrogen in the upper troposphere

    Directory of Open Access Journals (Sweden)

    B. H. Henderson

    2011-01-01

    Full Text Available Regional and global chemical transport models underpredict NOx (NO + NO2 in the upper troposphere where it is a precursor to the greenhouse gas ozone. The NOx bias has been shown in model evaluations using aircraft data (Singh et al., 2007 and total column NO2 (molecules cm−2 from satellite observations (Napelenok et al., 2008. The causes of NOx underpredictions have yet to be fully understood due to the interconnected nature of simulated emission, transport, and chemistry processes. Recent observation-based studies, in the upper troposphere, identify chemical rate coefficients as a potential source of error (Olson et al., 2006; Ren et al., 2008. Since typical chemistry evaluation techniques are not available for upper tropospheric conditions, this study develops an evaluation platform from in situ observations, stochastic convection, and deterministic chemistry. We derive a stochastic convection model and optimize it using two simulated datasets of time since convection, one based on meteorology, and the other on chemistry. The chemistry surrogate for time since convection is calculated using seven different chemical mechanisms, all of which predict shorter time since convection than our meteorological analysis. We evaluate chemical simulations by inter-comparison and by pairing results with observations based on NOx:HNO3, a photochemical aging indicator. Inter-comparison reveals individual chemical mechanism biases and recommended updates. Evaluation against observations shows that all chemical mechanisms overpredict NOx removal relative to long-lived methanol and carbon monoxide. All chemical mechanisms underpredict observed NOx by at least 30%, and further evaluation is necessary to refine simulation sensitivities to initial conditions and chemical rate uncertainties.

  6. Exposure assessment for nitrogen oxides and carbon monoxide in German hard coal mining.

    Science.gov (United States)

    Dahmann, Dirk; Morfeld, Peter; Monz, Christian; Noll, Birgit; Gast, Frank

    2009-11-01

    The exposure situation of German hard coal miners with respect to the components nitrogen monoxide and nitrogen dioxide. Carbon monoxide was measured additionally and the results are displayed but not discussed in detail in this paper. The data were used to estimate personal long-term exposures in an inception cohort. For all three components, time weighted 8-h shift values were determined for typical groups of coalminers according to the European measurement standard. An expert panel from the coal mining company made an effort to estimate major potential changes in the exposure situation. The main sources of nitrogen oxides and carbon monoxide in hard coal mining were the diesel engines. Blasting fumes contributed only to a lesser degree and with different exposure characteristics, e.g. much reduced NO(2) levels compared to the mines' rear areas. As rough 8 h-shift averages describing the current exposure situation, we found 1.35 ppm NO and 0.21 ppm NO(2) for the diesel engine drivers. Blasting specialists were more difficult to evaluate but rough 8 h-shift averages of 0.84 ppm NO and 0.014 ppm NO(2) could be estimated from our measurement series. By applying these data and the estimates of experts about the retrospective exposure situation to a cohort of 1,369 coalminers, we derived mean (max) cumulative exposures in ppm x number of shifts of 1,748 (5,928) for NO and 19.6 (1,013) for NO(2) when summarizing over the follow-up period from 1974 until 1998. Especially for the diesel engine drivers, exposure can be regarded as rather high, in particular, when compared to recommended limits by SCOEL and MAK, though the exposures have been in line with the enforced German occupational exposure limits. Whether this exposure situation has caused adverse health effects will be investigated epidemiologically.

  7. Efficient decomposition of environmentally persistent perfluorocarboxylic acids by use of persulfate as a photochemical oxidant.

    Science.gov (United States)

    Hori, Hisao; Yamamoto, Ari; Hayakawa, Etsuko; Taniyasu, Sachi; Yamashita, Nobuyoshi; Kutsuna, Shuzo; Kiatagawa, Hiroshi; Arakawa, Ryuichi

    2005-04-01

    Photochemical decomposition of persistent perfluorocarboxylic acids (PFCAs) in water by use of persulfate ion (S2O8(2-)) was examined to develop a technique to neutralize stationary sources of PFCAs. Photolysis of S2O8(2-) produced highly oxidative sulfate radical anions (SO4-), which efficiently decomposed perfluorooctanoic acid (PFOA) and other PFCAs bearing C4-C8 perfluoroalkyl groups. The major products were F- and CO2; also, small amounts of PFCAs with shorter than initial chain lengths were detected in the reaction solution. PFOA at a concentration of 1.35 mM (typical of that in untreated wastewater after an emulsifying process in fluoropolymer manufacture) was completely decomposed by a photochemical system with 50 mM S2O8(2-) and 4 h of irradiation from a 200-W xenon-mercury lamp. The initial PFOA decomposition rate was 11 times higherthan with photolysis alone. All sulfur-containing species in the reaction solution were eventually transformed to sulfate ions by this method. This method was successfully applied to the decomposition of perfluorononanoic acid contained in a floor wax solution.

  8. Photochemical decoration of silver nanoparticles on graphene oxide nanosheets and their optical characterization

    Energy Technology Data Exchange (ETDEWEB)

    Lan, Nguyen Thi; Chi, Do Thi; Dinh, Ngo Xuan; Hung, Nguyen Duy; Lan, Hoang [Department of Nanoscience and Nanotechnology, Advanced Institute for Science and Technology (AIST), Hanoi University of Science and Technology (HUST), No. 1 Dai Co Viet Street, Hai Ba Trung District, Hanoi (Viet Nam); Tuan, Pham Anh [Vietnam Metrology Institute, 08 Hoang Quoc Viet Road, Cau Giay District, Hanoi (Viet Nam); Thang, Le Hong [School of Materials Science and Engineering, Hanoi University of Science and Technology (HUST), 01 Dai Co Viet Street, Hai Ba Trung District, Hanoi (Viet Nam); Trung, Nguyen Ngoc [School of Engineering Physics, Hanoi University of Science and Technology (HUST), 01 Dai Co Viet Street, Hai Ba Trung District, Hanoi (Viet Nam); Hoa, Nguyen Quang [Department of Physics, Hanoi University of Science, 334 Nguyen Trai, Thanh Xuan, Hanoi (Viet Nam); Huy, Tran Quang [Laboratory for Ultrastructure and Bionanotechnology (LUBN), National Institute of Hygiene and Epidemiology (NIHE), No. 1 Yecxanh Street, Hai Ba Trung District, Hanoi (Viet Nam); Quy, Nguyen Van [International Training Institute for Materials Science (ITIMS), Hanoi University of Science and Technology (HUST), 01 Dai Co Viet Street, Hai Ba Trung District, Hanoi (Viet Nam); Duong, Thanh-Tung [Department of Materials Engineering, Chungnam National University, Daeduk Science Town, 305-764 Daejeon (Korea, Republic of); Phan, Vu Ngoc [Department of Nanoscience and Nanotechnology, Advanced Institute for Science and Technology (AIST), Hanoi University of Science and Technology (HUST), No. 1 Dai Co Viet Street, Hai Ba Trung District, Hanoi (Viet Nam); Le, Anh-Tuan, E-mail: tuan.leanh1@hust.edu.vn [Department of Nanoscience and Nanotechnology, Advanced Institute for Science and Technology (AIST), Hanoi University of Science and Technology (HUST), No. 1 Dai Co Viet Street, Hai Ba Trung District, Hanoi (Viet Nam)

    2014-12-05

    Highlights: • A photochemical method for effective decoration of the Ag-NPs on GO nanosheets is presented. • The average size of the Ag-NPs on the GO nanosheets obtained ∼6–7 nm with uniform size distribution. • Surface interaction of Ag-NPs with GO nanosheets leads to surface plasmon-enhanced luminescence. - Abstract: Nanohybrid materials based on silver nanoparticles (Ag-NPs) and graphene oxide (GO) are attracting considerable research interest because of their potential many applications including surface-enhanced Raman scattering, catalysis, sensors, biomedicine and antimicrobials. In this study, we established a simple and effective method of preparing a finely dispersed Ag-GO aqueous solution using modified Hummer and photochemical technique. The Ag-NPs formation on GO nanosheets was analyzed by X-ray diffraction, transmission electron microscopy, Raman spectroscopy, and Fourier-transform infrared spectroscopy. The average size of Ag-NPs on the GO nanosheets was approximately 6–7 nm with nearly uniform size distribution. The Ag-GO nanohybrid also exhibits an adsorption band at 435 nm because of the presence of Ag-NPs on the GO nanosheets. Photoluminescence emission of the Ag-GO nanohybrid was found at 400 and 530 nm, which can be attributed to the interaction between the luminescence of exploited GO nanosheets and localized surface plasmon resonance from metallic Ag-NPs. The observed excellent optical properties of the as-prepared Ag-GO nanohybrid showed a significant potential for optoelectronics applications.

  9. Tracing Gas and Particle Phase Oxidation From Engine Sources as a Function of Fuel Type, Load, and Photochemical Age

    Science.gov (United States)

    Friedman, B.; Farmer, D.; Jathar, S.; Galang, A.; Fulgham, R.; Link, M.; Brophy, P.

    2015-12-01

    Motor vehicle emissions are an important source of anthropogenic gases and particles in the atmosphere. To study the gas and particle phase emissions, an HR-TOF-AMS and HR-TOF-CIMS were deployed at the CSU Engines Lab, along with an oxidative flow reactor, to measure emissions from a 4.5 L John Deere engine, which ran either diesel or biodiesel fuel. Concurrent gas-phase and particle-phase measurements allowed determination of the gas-phase and particle-phase oxidation properties as a function of fuel type, fuel load, and photochemical age. The impacts of particulate filers on composition and oxidation state were also assessed. While aerosol composition and associated oxidation properties for the biodiesel and diesel fuel types were similar, differences in photochemical production existed for the amount of load, or efficiency of the engine. The mean particulate oxygen to carbon ratios (O:C) and mean hydrogen to carbon ratios (H:C) moved from an initial 0.1 and 2 to a final 0.55 and 1.6, respectively, upon idle biodiesel and diesel engine exhaust exposure to approximately 7 days of OH exposure. The more efficient higher load biodiesel and diesel engine exhaust experienced less changes in the mean O:C and H:C values (an initial 0.1 and 2 to a final 0.3 and 1.7, respectively) with approximately the same amount of OH exposure. Despite largely scrubbing the majority of particles from the engine exhaust, experiments with engine particulate filters still showed photochemical production of oxidized particle-phase species at high photochemical ages, similar to that of idle engine exhaust without any particulate filters. Bulk gas-phase data was compared to bulk aerosol data in Van Krevelen space in order to understand how particle-phase oxidation traces gas-phase oxidation as a function of fuel type, engine load, and photochemical age.

  10. Dosimetry Determines the Initial OH Radical Concentration in Fast Photochemical Oxidation of Proteins (FPOP)

    Science.gov (United States)

    Niu, Ben; Zhang, Hao; Giblin, Daryl; Rempel, Don L.; Gross, Michael L.

    2015-05-01

    Fast photochemical oxidation of proteins (FPOP) employs laser photolysis of hydrogen peroxide to give OH radicals that label amino acid side-chains of proteins on the microsecond time scale. A method for quantitation of hydroxyl radicals after laser photolysis is of importance to FPOP because it establishes a means to adjust the yield of •OH, offers the opportunity of tunable modifications, and provides a basis for kinetic measurements. The initial concentration of OH radicals has yet to be measured experimentally. We report here an approach using isotope dilution gas chromatography/mass spectrometry (GC/MS) to determine quantitatively the initial •OH concentration (we found ~0.95 mM from 15 mM H2O2) from laser photolysis and to investigate the quenching efficiencies for various •OH scavengers.

  11. First-Principles Study of Photochemical Activation of CO2 by Ti-based Oxides

    Science.gov (United States)

    He, Haiying; Zapol, Peter; Curtiss, Larry

    2013-03-01

    The photochemical conversion of CO2 and H2O into energy-bearing hydrocarbon fuels provides an attractive way of mitigating the green-house gas CO2 and utilizing solar energy as a sustainable energy source. However, due to the high reduction potential and chemical inertness of CO2 molecules, the conversion rate of CO2 is impractically low. The activation of CO2 is critical in facilitating further reactions. By carrying out first-principles calculations of reaction pathways from CO2 to CO2-anions on Ti-based oxides including zeolites in the presence of photoexcited electrons, we have studied the initial step of CO2 activation via 1e transfer. It is shown that the CO2 reactivity of these surfaces strongly depends on the crystal structure, surface orientation, and presence of defects. This opens a new dimension in surface structure modification to enhance the CO2 adsorption and reduction on semiconductor surfaces.

  12. Mechanisms in Ruthenium(II) photochemistry and Iron(III) catalyzed oxidations : Photochemical, Electrochemical and Spectroscopic studies

    NARCIS (Netherlands)

    Unjaroen, Duenpen

    2017-01-01

    In this thesis, photochemical, electrochemical and spectroscopic studies of Ru(II), Fe(II), and Fe(III) complexes are described. The overall goal in this studies was to understanding process that occur during oxidation catalysis and photo irradiation and especially the changes in the structure that

  13. Highly n-Type Titanium Oxide as an Electronically Active Support for Platinum in the Catalytic Oxidation of Carbon Monoxide

    KAUST Repository

    Baker, L. Robert

    2011-08-18

    The role of the oxide-metal interface in determining the activity and selectivity of chemical reactions catalyzed by metal particles on an oxide support is an important topic in science and industry. A proposed mechanism for this strong metal-support interaction is electronic activation of surface adsorbates by charge carriers. Motivated by the goal of using electronic activation to drive nonthermal chemistry, we investigated the ability of the oxide support to mediate charge transfer. We report an approximately 2-fold increase in the turnover rate of catalytic carbon monoxide oxidation on platinum nanoparticles supported on stoichiometric titanium dioxide (TiO2) when the TiO2 is made highly n-type by fluorine (F) doping. However, for nonstoichiometric titanium oxide (TiOX<2) the effect of F on the turnover rate is negligible. Studies of the titanium oxide electronic structure show that the energy of free electrons in the oxide determines the rate of reaction. These results suggest that highly n-type TiO2 electronically activates adsorbed oxygen (O) by electron spillover to form an active O- intermediate. © 2011 American Chemical Society.

  14. Oxygen permeation flux through La1-ySryFeO3 limited by the carbon monoxide oxidation rate

    NARCIS (Netherlands)

    van Hassel, B.A.; van Hassel, B.A.; ten Elshof, Johan E.; Bouwmeester, Henricus J.M.

    1995-01-01

    The oxygen permeation flux through La1-ySryFeO3-δ (y = 0.1, 0.2) in a large oxygen partial pressure gradient (air/CO, CO2 mixture) was found to be limited by the carbon monoxide oxidation rate at the low oxygen partial pressure side of the membrane. The oxygen permeation flux through the membrane

  15. The phylogenetic distribution and ecological role of carbon monoxide oxidation in the genus Burkholderia.

    Science.gov (United States)

    Weber, Carolyn F; King, Gary M

    2012-01-01

    Burkholderia is a physiologically and ecologically diverse genus that occurs commonly in assemblages of soil and rhizosphere bacteria. Although Burkholderia is known for its heterotrophic versatility, we demonstrate that 14 distinct environmental isolates oxidized carbon monoxide (CO) and possessed the gene encoding the catalytic subunit of form I CO dehydrogenase (coxL). DNA from a Burkholderia isolate obtained from a passalid beetle also contained coxL as do the genomic sequences of species H160 and Ch1-1. Isolates were able to consume CO at concentrations ranging from 100 ppm (vol/vol) to sub-ambient ( 2.5 mM), but mixotrophic consumption of CO and pyruvate occurred when initial pyruvate concentrations were lower (c. 400 lM). With the exception of an isolate most closely related to Burkholderia cepacia, all CO-oxidizing isolates examined were members of a nonpathogenic clade and were most closely related to Burkholderia species, B. caledonica, B. fungorum, B. oxiphila, B. mimosarum, B. nodosa, B. sacchari, B. bryophila, B. ferrariae, B. ginsengesoli, and B. unamae. However, none of these type strains oxidized CO or contained coxL based on results from PCR analyses. Collectively, these results demonstrate that the presence of CO oxidation within members of the Burkholderia genus is variable but it is most commonly found among rhizosphere inhabitants that are not closely related to B. cepacia.

  16. Interfacial Cu+ promoted surface reactivity: Carbon monoxide oxidation reaction over polycrystalline copper-titania catalysts

    Science.gov (United States)

    Senanayake, Sanjaya D.; Pappoe, Naa Adokaley; Nguyen-Phan, Thuy-Duong; Luo, Si; Li, Yuanyuan; Xu, Wenqian; Liu, Zongyuan; Mudiyanselage, Kumudu; Johnston-Peck, Aaron C.; Frenkel, Anatoly I.; Heckler, Ilana; Stacchiola, Dario; Rodriguez, José A.

    2016-10-01

    We have studied the catalytic carbon monoxide (CO) oxidation (CO + 0.5O2 → CO2) reaction using a powder catalyst composed of both copper (5 wt.% loading) and titania (CuOx-TiO2). Our study was focused on revealing the role of Cu, and the interaction between Cu and TiO2, by systematic comparison between two nanocatalysts, CuOx-TiO2 and pure CuOx. We interrogated these catalysts under in situ conditions using X-ray diffraction (XRD), X-ray absorption fine structure (XAFS) and diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) to probe the structure and electronic properties of the catalyst at all stages of the reaction and simultaneously probe the surface states or intermediates of this reaction. With the aid of several ex situ characterization techniques including transmission electron microscopy (TEM), the local catalyst morphology and structure were also studied. Our results show that a CuOx-TiO2 system is more active than bulk CuOx for the CO oxidation reaction due to its lower onset temperature and better stability at higher temperatures. Our results also suggest that surface Cu+ species observed in the CuOx-TiO2 interface are likely to be a key player in the CO oxidation mechanism, while implicating that the stabilization of this species is probably associated with the oxide-oxide interface. Both in situ DRIFTS and XAFS measurements reveal that there is likely to be a Cu(Ti)-O mixed oxide at this interface. We discuss the nature of this Cu(Ti)-O interface and interpret its role on the CO oxidation reaction.

  17. Cobalt Oxide Nanosheet and CNT Micro Carbon Monoxide Sensor Integrated with Readout Circuit on Chip

    Science.gov (United States)

    Dai, Ching-Liang; Chen, Yen-Chi; Wu, Chyan-Chyi; Kuo, Chin-Fu

    2010-01-01

    The study presents a micro carbon monoxide (CO) sensor integrated with a readout circuit-on-a-chip manufactured by the commercial 0.35 μm complementary metal oxide semiconductor (CMOS) process and a post-process. The sensing film of the sensor is a composite cobalt oxide nanosheet and carbon nanotube (CoOOH/CNT) film that is prepared by a precipitation-oxidation method. The structure of the CO sensor is composed of a polysilicon resistor and a sensing film. The sensor, which is of a resistive type, changes its resistance when the sensing film adsorbs or desorbs CO gas. The readout circuit is used to convert the sensor resistance into the voltage output. The post-processing of the sensor includes etching the sacrificial layers and coating the sensing film. The advantages of the sensor include room temperature operation, short response/recovery times and easy post-processing. Experimental results show that the sensitivity of the CO sensor is about 0.19 mV/ppm, and the response and recovery times are 23 s and 34 s for 200 ppm CO, respectively. PMID:22294897

  18. Cobalt Oxide Nanosheet and CNT Micro Carbon Monoxide Sensor Integrated with Readout Circuit on Chip

    Directory of Open Access Journals (Sweden)

    Ching-Liang Dai

    2010-03-01

    Full Text Available The study presents a micro carbon monoxide (CO sensor integrated with a readout circuit-on-a-chip manufactured by the commercial 0.35 μm complementary metal oxide semiconductor (CMOS process and a post-process. The sensing film of the sensor is a composite cobalt oxide nanosheet and carbon nanotube (CoOOH/CNT film that is prepared by a precipitation-oxidation method. The structure of the CO sensor is composed of a polysilicon resistor and a sensing film. The sensor, which is of a resistive type, changes its resistance when the sensing film adsorbs or desorbs CO gas. The readout circuit is used to convert the sensor resistance into the voltage output. The post-processing of the sensor includes etching the sacrificial layers and coating the sensing film. The advantages of the sensor include room temperature operation, short response/recovery times and easy post-processing. Experimental results show that the sensitivity of the CO sensor is about 0.19 mV/ppm, and the response and recovery times are 23 s and 34 s for 200 ppm CO, respectively.

  19. Evaluation of simulated photochemical partitioning of oxidized nitrogen in the upper troposphere

    Directory of Open Access Journals (Sweden)

    B. H. Henderson

    2010-08-01

    Full Text Available Regional and global chemical transport models underpredict NOx (NO+NO2 in the upper troposphere where it is a precursor to the greenhouse gas ozone. The NOx bias been shown in model evaluations using aircraft data (Singh et al., 2007 and total column NO2 (molecules cm−2 from satellite observations (Napelenok et al., 2008. The causes of NOx underpredictions have yet to be fully understood due to the interconnected nature of simulated emission, transport, and chemistry processes. Recent observation-based studies suggest that, in the upper troposphere, simulated chemistry overpredicts hydrogen radicals (OH and HO2 and would convert NOx to HNO3 too quickly (Olson et al., 2006; Bertram et al., 2007; Ren et al., 2008. Since typical chemistry evaluation techniques are not available for upper tropospheric conditions, this study develops an evaluation platform from in situ observations, stochastic convection, and deterministic chemistry. We derive a stochastic convection model and optimize it using two simulated datasets of time since convection, one based on meteorology and the other on chemistry. The chemistry surrogate for time since convection is calculated using seven different chemical mechanisms, all of which predict shorter time since convection than our meteorological analysis. We evaluate chemical simulations by inter-comparison and by pairing results with observations based on NOx:HNO3, a photochemical aging indicator. Inter-comparison reveals individual chemical mechanism biases and recommended updates. Evaluation against observations shows that all chemical mechanisms overpredict NOx removal relative to long-lived methanol and carbon monoxide. All chemical mechanisms underpredict observed NOx by at least 30%, and further evaluation is necessary to refine simulation

  20. Catalytic reduction of nitric oxide with carbon monoxide on copper-cobalt oxides supported on nano-titanium dioxide.

    Science.gov (United States)

    Chen, Xia; Zhang, Junfeng; Huang, Yan; Tong, Zhiquan; Huang, Ming

    2009-01-01

    A series of copper-cobalt oxides supported on nano-titanium dioxide were prepared for the reduction of nitric oxide with carbon monoxide and characterized using techniques such as XRD, BET and TPR. Catalyst CuCoOx/TiO2 with Cu/Co molar ratio of 1/2, Cu-Co total loading of 30% at the calcination temperature of 350 degrees C formed CuCo2O4 spinel and had the highest activity. NO conversion reached 98.9% at 200 degrees C. Mechanism of the reduction was also investigated, N2O was mainly yielded below 100 degrees C, while N2 was produced instead at higher temperature. O2 was supposed to accelerate the reaction between NOx and CO for its oxidation of NO to give more easily reduced NO2, but the oxidation of CO by O2 to CO2 decreased the speed of the reaction greatly. Either SO2 or H2O had no adverse impact on the activity of NO reduction; however, in the presence of both SO2 and H2O, the catalyst deactivated quickly.

  1. Carbon monoxide pollution aggravates ischemic heart failure through oxidative stress pathway.

    Science.gov (United States)

    Reboul, Cyril; Boissière, Julien; André, Lucas; Meyer, Gregory; Bideaux, Patrice; Fouret, Gilles; Feillet-Coudray, Christine; Obert, Philippe; Lacampagne, Alain; Thireau, Jérôme; Cazorla, Olivier; Richard, Sylvain

    2017-01-03

    Risk of hospital readmission and cardiac mortality increases with atmospheric pollution for patients with heart failure. The underlying mechanisms are unclear. Carbon monoxide (CO) a ubiquitous environmental pollutant could be involved. We explored the effect of daily exposure of CO relevant to urban pollution on post-myocardial infarcted animals. Rats with ischemic heart failure were exposed 4 weeks to daily peaks of CO mimicking urban exposure or to standard filtered air. CO exposure worsened cardiac contractile dysfunction evaluated by echocardiography and at the cardiomyocyte level. In line with clinical reports, the animals exposed to CO also exhibited a severe arrhythmogenic phenotype with numerous sustained ventricular tachycardias as monitored by surface telemetric electrocardiograms. CO did not affect cardiac β-adrenergic responsiveness. Instead, mitochondrial dysfunction was exacerbated leading to additional oxidative stress and Ca(2+) cycling alterations. This was reversed following acute antioxidant treatment of cardiomyocytes with N-acetylcysteine confirming involvement of CO-induced oxidative stress. Exposure to daily peaks of CO pollution aggravated cardiac dysfunction in rats with ischemic heart failure by specifically targeting mitochondria and generating ROS-dependent alterations. This pathway may contribute to the high sensibility and vulnerability of individuals with cardiac disease to environmental outdoor air quality.

  2. Carbon monoxide pollution aggravates ischemic heart failure through oxidative stress pathway

    Science.gov (United States)

    Reboul, Cyril; Boissière, Julien; André, Lucas; Meyer, Gregory; Bideaux, Patrice; Fouret, Gilles; Feillet-Coudray, Christine; Obert, Philippe; Lacampagne, Alain; Thireau, Jérôme; Cazorla, Olivier; Richard, Sylvain

    2017-01-01

    Risk of hospital readmission and cardiac mortality increases with atmospheric pollution for patients with heart failure. The underlying mechanisms are unclear. Carbon monoxide (CO) a ubiquitous environmental pollutant could be involved. We explored the effect of daily exposure of CO relevant to urban pollution on post-myocardial infarcted animals. Rats with ischemic heart failure were exposed 4 weeks to daily peaks of CO mimicking urban exposure or to standard filtered air. CO exposure worsened cardiac contractile dysfunction evaluated by echocardiography and at the cardiomyocyte level. In line with clinical reports, the animals exposed to CO also exhibited a severe arrhythmogenic phenotype with numerous sustained ventricular tachycardias as monitored by surface telemetric electrocardiograms. CO did not affect cardiac β–adrenergic responsiveness. Instead, mitochondrial dysfunction was exacerbated leading to additional oxidative stress and Ca2+ cycling alterations. This was reversed following acute antioxidant treatment of cardiomyocytes with N-acetylcysteine confirming involvement of CO-induced oxidative stress. Exposure to daily peaks of CO pollution aggravated cardiac dysfunction in rats with ischemic heart failure by specifically targeting mitochondria and generating ROS-dependent alterations. This pathway may contribute to the high sensibility and vulnerability of individuals with cardiac disease to environmental outdoor air quality. PMID:28045070

  3. Transient kinetic modeling of the ethylene and carbon monoxide oxidation over a commercial automotive exhaust gas catalyst

    Energy Technology Data Exchange (ETDEWEB)

    Harmsen, J.M.A.; Hoebink, J.H.B.J.; Schouten, J.C.

    2000-03-01

    The transient kinetics of ethylene oxidation by oxygen over a commercial Pt/Rh/CeO{sub 2}/{gamma}-Al{sub 2}O{sub 3} three-way catalyst were modeled. Experiments were carried out in a fixed-bed microreactor with two separate inlets, enabling alternate feeding of ethylene and oxygen with frequencies up to {1/4} Hz. The experimental conditions resemble the cold-start period of an Otto engine in a car. Two types of adsorbed ethylene species seem to exist. A selective catalyst deactivation for oxygen adsorption, due to deposition of carbonaceous species, was found. A kinetic model was developed, based on elementary reaction steps, that allows one to describe the experiments quantitatively. Furthermore, this model was combined with the published model for transient carbon monoxide oxidation over the same catalyst, which enables one to predict the results of simultaneous ethylene and carbon monoxide oxidation. Both components react in rather distinct zones, with ethylene being converted only when carbon monoxide oxidation is almost complete.

  4. Experimental Measurements of the Effects of Photo-chemical Oxidation on Aerosol Emissions in Aircraft Exhaust

    Science.gov (United States)

    Miracolo, M. A.; Presto, A. A.; Hennigan, C. J.; Nguyen, N.; Ranjan, M.; Reeder, A.; Lipsky, E.; Donahue, N. M.; Robinson, A. L.

    2009-12-01

    Many military and commercial airfields are located in non-attainment areas for particulate matter (PM2.5), but the contribution of emissions from in-use aircraft to local and regional PM2.5 concentrations is uncertain. In collaboration with the Pennsylvania Air National Guard 171st Air Refueling Wing, the Carnegie Mellon University (CMU) Mobile Laboratory was deployed to measure fresh and aged emissions from a CFM56-2B1 gas-turbine engine mounted on a KC-135 Stratotanker airframe. The CFM-56 family of engine powers many different types of military and civilian aircraft, including the Boeing 737 and several Airbus models. It is one of the most widely deployed models of engines in the world. The goal of this work was to measure the gas-particle partitioning of the fresh emissions at atmospherically relevant conditions and to investigate the effect of atmospheric oxidation on aerosol loadings as the emissions age. Emissions were sampled from an inlet installed one meter downstream of the engine exit plane and transferred into a portable smog chamber via a heated inlet line. Separate experiments were conducted at different engine loads ranging from ground idle to take-off rated thrust. During each experiment, some diluted exhaust was added to the chamber and the volatility of the fresh emissions was then characterized using a thermodenuder. After this characterization, the chamber was exposed to either ambient sunlight or UV lights to initiate photochemical oxidation, which produced secondary aerosol and ozone. A suite of gas and particle-phase instrumentation was used to characterize the evolution of the gas and particle-phase emissions, including an aerosol mass spectrometer (AMS) to measure particle size and composition distributions. Fresh emissions of fine particles varied with engine load with peak emission factors at low and high loads. At high engine loads, the fresh emissions were dominated by black carbon; at low loads volatile organic carbon emissions were

  5. REDUCTION OF NITRIC OXIDE BY CARBON MONOXIDE OVER A SILICA SUPPORTED PLATINUM CATALYST: INFRARED AND KINETIC STUDIES

    Energy Technology Data Exchange (ETDEWEB)

    Lorimer, D.H.

    1978-08-01

    The reduction of nitric oxide by carbon monoxide over a 4.5 weight precent platinum catalyst supported on silica was studied at 300 C. Reaction rate data was obtained together with in situ infrared spectra of species on the catalyst surface. The kinetics of the system were found to exhibit two distinct trends, depending on the molar ratio of CO/NO in the reactor. For net reducing conditions (CO/NO> 1) the catalyst underwent a transient deactivation, the extent of which was dependent on the specific CO/NO ratio during reaction. Reactivation of the catalyst was obtained with both oxidizing and reducing pretreatments. For molar feed ratios of CO/NO less than one, carbon monoxide conversion was typically 95 to 100%, resulting in strongly oxidizing conditions over the catalyst. Under these conditions no deactivation was apparent. Infrared spectra recorded under reaction conditions revealed intense bands at 2075 and 2300 cm{sup -1} , which were identified as carbon monoxide adsorbed on Pt and Si-NCO, respectively. Isocyanate bands formed under reducing conditions were more intense and exhibited greater stability than those formed under oxidizing conditions. A reaction mechanism based on the dissociation of nitric oxide as the rate-limiting step was used to correlate nitric oxide reaction rates and nitrous oxide selectivities observed under reducing conditions. As part of this mechanism it is assumed that nitrous bxide is formed via a Langmuir-Hinshelwood process in which an adsorbed nitrogen atom reacts with an adsorbed nitric oxide molecule. The nitric oxide reaction rate was found to be first order in nitric oxide partial pressure, and inverse second order in carbon monoxide partial pressure. A mechanism is proposed to qualitatively explain the deactivation process observed under reducing conditions. The essential part of this mechanism is the formation of an isocyanate species on the Pt crystallites of the catalyst and the subsequent transient diffusion of these

  6. Thermal and Photochemical Reactions of NO2 on a Chromium (III) Oxide Surface

    Science.gov (United States)

    Nishino, N.; Finlayson-Pitts, B. J.

    2011-12-01

    Chromium oxide (Cr2O3) is a major component of the oxide layer on stainless steel surfaces. It is also widely used as pigment in paints and roofs and as a protective coating on various surfaces. While many studies have focused on the catalytic activity of Cr2O3 surfaces for selective catalytic reduction (SCR), less attention has been paid to its surface chemistry involving atmospherically important species such as NO2 under atmospheric conditions. In this study, we have investigated thermal and photochemical reactions of NO2 in the presence and the absence of water vapor, using a thin layer of Cr2O3 as a model for the surface of stainless steel as well as other similarly coated surfaces in the boundary layer. A 30 nm thick Cr2O3 film was deposited on a germanium attenuated total reflectance (ATR) crystal, and the changes in the surface species were monitored by Fourier Transform Infrared (FTIR) spectroscopy. Upon NO2 adsorption, nitrate (NO3-) ions appeared likely coordinated to Cr3+ ion(s). The NO3- peaks reversibly shifted when water vapor was added, suggesting that NO3- become solvated. Irradiation at 311 nm led to a decrease in NO3- ions under both dry and humid conditions. The major gas-phase species formed by the irradiation was NO under dry conditions, while NO2 was mainly formed in the presence of H2O. Possible mechanisms and the implications for heterogeneous NO2 chemistry in the boundary layer will be discussed. The results will also be compared to similar chemistry on other surfaces.

  7. Zinc Oxide-Multi Walled Carbon Nanotubes Nanocomposites for Carbon Monoxide Gas Sensor Application.

    Science.gov (United States)

    Alharbi, Najlaa D; Ansari, M Shahnawaze; Salah, Numan; Khayyat, Suzan A; Khan, Zishan H

    2016-01-01

    Zinc oxide (ZnO)/multi walled carbon nanotubes (MWCNTs) composites based sensors with different ZnO concentrations were fabricated to improve carbon monoxide (CO) gas sensing properties in comparison to the sensors based on bare MWCNTs. To study the structure, morphology and elemental composition of the resultant products, X-ray diffraction (XRD), Field emission scanning electron microscopy (FESEM) and Energy dispersive X-ray spectroscopy (EDS) were carried out. It has been observed that as the concentration of ZnO is increased more and more ZnO nanoparticles in the form of nodes get attached to MWCNTs resulting the reduction in average diameter of MWCNTs. The typical response of ZnO/MWCNTs composites based gas sensors for different CO concentrations (40, 100, 140 and 200 ppm) was studied by using very advanced sensing setup attached to I-V measurement system. Different sensing parameters such as: resistive response, sensitivity and response time were estimated at room temperature for all the fabricated sensors. The results indicated that the sensor based on nanocomposite which has 30 mg ZnO dispersed on 20 mg MWCNTs showing highest sensitivity and fastest response. All the sensors showed response times ranging from 8 to 23 seconds. The sensing mechanism behind the sensors based on ZnO/MWCNTs nanocomposites for CO gas at room temperature is also discussed in the present report.

  8. Nitric oxide modulates hypoxic pulmonary smooth muscle cell proliferation and apoptosis by regulating carbon monoxide pathway

    Institute of Scientific and Technical Information of China (English)

    Yan-fei WANG; Hong TIAN; Chao-shu TANG; Hong-fang JIN; Jun-bao DU

    2007-01-01

    Aim: To explore the role of carbon monoxide (CO) in the regulation of hypoxic pulmonary artery smooth muscle cell (PASMC) proliferation and apoptosis by nitric oxide (NO). Methods: PASMC of Wistar rats was cultured in vitro in the presence of a NO donor, sodium nitroprusside, or an inhibitor of heme oxygenase (HO), zinc protoporphyrin-IX, or under both normoxic and hypoxic conditions.Nitrite and carboxyhemoglobin in PASMC medium were detected with spectrophotometry. The proliferating and apoptotic percentage of PASMC was measured by flow cytometry. The expression of HO-1 mRNA in PASMC was analyzed by fluorescent real-time quantitative PCR, and the proliferating cell nuclear antigen and caspase-3 were examined by immunocytochemical analysis. Results: The results showed that hypoxia suppressed NO generation from PASMC, which promoted hypoxic PASMC proliferation and induced apoptosis. Meanwhile, hy-poxia induced HO-1 expression in PASMC and promoted CO production from PASMC, which inhibited PASMC proliferation and regulated PASMC apoptosis. NO upregulated the expression of HO-1 mRNA in hypoxic PASMC; NO also inhib-ited proliferation and promoted apoptosis of hypoxic PASMC, possibly by regu-lating the production of CO. Conclusion: The results indicated that CO could inhibit proliferation and regulate apoptosis of PASMC, and NO inhibited prolifera-tion and promoted apoptosis of hypoxic PASMC, possibly by regulating the pro-duction of CO.

  9. Interaction between endogenous nitric oxide and carbon monoxide in the pathogenesis of hypoxic pulmonary hypertension

    Institute of Scientific and Technical Information of China (English)

    2003-01-01

    The aim of the study was to investigate the interaction between nitric oxygenase (NOS)/ nitric oxide (NO) and heme oxygenase (HO)/ carbon monoxide (CO) system in the pathogenesis of hypoxic pulmonary hypertension. On a rat model of hypoxic pulmonary hypertension, the pulmonary artery pressure was measured, and NO formation and expression of NOS in pulmonary tissues were examined after treatment with ZnPP-IX, an HO-1 inhibitor. The pulmonary artery pressure, CO formation and expression of HO-1 in pulmonary tissues were examined after treatment with L-NAME, a NOS inhibitor. We found that pulmonary hypertension developed after 2-week hypoxia, while the concentration of NO in the pulmonary tissue homogenates and the expression of NOS in intrapulmonary artery endothelial cells decreased markedly. ZnPP-IX worsened pulmonary hypertension of hypoxic rats. However, it increased endogenous production of NO and the expression of NOS obviously. The concentration of CO in the pulmonary tissue homogenates and the expression of HO-1 in intrapulmonary artery smooth muscle cells increased markedly with hypoxic pulmonary hypertension. L-NAME worsened pulmonary hypertension of hypoxic rats, but inhibited CO formation and HO-1 expression (P < 0.01). The results of this study suggested that endogenous NOS/NO and HO/CO systems might interact with each other and therefore play an important regulating role in hypoxic pulmonary hypertension.

  10. A simultaneous single breath measurement of pulmonary diffusing capacity with nitric oxide and carbon monoxide.

    Science.gov (United States)

    Borland, C D; Higenbottam, T W

    1989-01-01

    Pulmonary diffusing capacity (DL) for carbon monoxide (CO) and nitric oxide (NO) were simultaneously measured in man using the single breath method, by adding 4O ppm of NO to the inspired gas and analysing the expirate for NO by a chemiluminescent method. The mean ratio of DLNO to DLCO in thirteen subjects was 4.3 (SD 0.3), mean DLNO = 49 mmol.min-1.kPa-1 (SD 10) and mean DLCO = 11 mmol.min-1.kPa-1 (SD 2). An increase in alveolar oxygen concentration from a mean of 18 to 68% in five subjects was associated with a 54% fall in DLCO but no change in DLNO. A reduction of lung volume from total lung capacity (TLC) (mean of 7 l) to a mean volume of 3.9 l in five subjects caused a fall in both DLNO (by 34%) and DLCO (by 8%). With 175 watts cycle exercise in three subjects the DLCO rose by 45% and DLNO by 25%. Since NO reacts much faster with haemoglobin than CO, DLNO should be influenced much less by reaction with haemoglobin, and perhaps represents a better index for the diffusing capacity of the alveolar-capillary membrane (Dm) than DLCO.

  11. Control of Disease Tolerance to Malaria by Nitric Oxide and Carbon Monoxide

    Directory of Open Access Journals (Sweden)

    Viktória Jeney

    2014-07-01

    Full Text Available Nitric oxide (NO and carbon monoxide (CO are gasotransmitters that suppress the development of severe forms of malaria associated with Plasmodium infection. Here, we addressed the mechanism underlying their protective effect against experimental cerebral malaria (ECM, a severe form of malaria that develops in Plasmodium-infected mice, which resembles, in many aspects, human cerebral malaria (CM. NO suppresses the pathogenesis of ECM via a mechanism involving (1 the transcription factor nuclear factor erythroid 2-related factor 2 (NRF-2, (2 induction of heme oxygenase-1 (HO-1, and (3 CO production via heme catabolism by HO-1. The protection afforded by NO is associated with inhibition of CD4+ T helper (TH and CD8+ cytotoxic (TC T cell activation in response to Plasmodium infection via a mechanism involving HO-1 and CO. The protective effect of NO and CO is not associated with modulation of host pathogen load, suggesting that these gasotransmitters establish a crosstalk-conferring disease tolerance to Plasmodium infection.

  12. Alleviation of copper-induced oxidative damage in Chlamydomonas reinhardtii by carbon monoxide.

    Science.gov (United States)

    Zheng, Qi; Meng, Qian; Wei, Yuan Yuan; Yang, Zhi Min

    2011-08-01

    Carbon monoxide (CO) is an endogenous gaseous molecule in plants and animals. Recent studies have shown that it is one of the most essential cellular components regulating many aspects of plant growth and development. However, whether CO regulates the green algae adaptive response to heavy metal toxicity is unknown. The present study investigated the role of CO in regulating Cu-induced oxidative stress in eukaryotic algae Chlamydomonas reinhardtii. Cells pretreated with 5 μM CO for 30 min and followed by exposure to 5 μM Cu(II) for 4 days showed attenuated toxicity. The CO-improved growth of algae was correlated with reduced lipid peroxidation and increased chlorophyll accumulation. The beneficial effect of CO was confirmed by histochemical staining with reactive oxygen species. Further, treatment with 5 μM CO increased the activity of catalase with Cu. However, a reduced superoxide dismutase activity was observed in the CO + Cu-treated algae compared to the control (activity of Cu treatment alone). Under the same condition, the activity of ascorbate peroxidase was not significantly changed. These results suggest that CO can play an important role in regulating the response of algae to Cu stress.

  13. Laboratory investigation of photochemical oxidation of organic aerosol from wood fires – Part 2: Analysis of aerosol mass spectrometer data

    Directory of Open Access Journals (Sweden)

    A. P. Grieshop

    2008-09-01

    Full Text Available Experiments were conducted to investigate the effects of photo-oxidation on organic aerosol (OA in dilute wood smoke by exposing emissions from soft- and hard-wood fires to UV light in a smog chamber. This paper focuses on changes in OA composition measured using a unit mass resolution quadrupole Aerosol Mass Spectrometer (AMS. The results highlight how photochemical processing can lead to considerable evolution of the mass, the volatility and the level of oxygenation of biomass-burning OA. Photochemical oxidation produced substantial new OA, more than doubling the primary contribution after a few hours of aging under typical summertime conditions. Aging decreased the OA volatility of the total OA as measured with a thermodenuder; it also made the OA progressively more oxygenated in every experiment. With explicit knowledge of the condensed-phase mass spectrum (MS of the primary emissions from each fire, each MS can be decomposed into primary and residual spectra throughout the experiment. The residual spectra provide an estimate of the composition of the photochemically produced OA. These spectra are also very similar to those of the oxygenated OA that dominates ambient AMS datasets. In addition, aged wood smoke spectra are shown to be similar to those from OA created by photo-oxidized dilute diesel exhaust and aged biomass-burning OA measured in urban and remote locations. This demonstrates that the oxygenated OA observed in the atmosphere can be produced by photochemical aging of dilute emissions from combustion of fuels containing both modern and fossil carbon.

  14. Kinetics of carbon monoxide oxidation over modified supported CuO catalysts

    Energy Technology Data Exchange (ETDEWEB)

    Loc, Luu Cam; Tri, Nguyen; Cuong, Hoang Tien; Thoang, Ho Si [Vietnam Academy of Science and Technology (VAST), Ho Chi Minh City (Viet Nam). Inst. of Chemical Technology; Agafonov, Yu.A.; Gaidai, N.A.; Lapidus, A.L. [Russian Academy of Sciences, Moscow (Russian Federation). N.D. Zelinsky Institute of Organic Chemistry

    2013-11-01

    The following supported on {gamma}-Al{sub 2}O{sub 3} catalysts: 10(wt.)%CuO (CuAl), 10%CuO+10%Cr{sub 2}O{sub 3} (CuCrAl) and 10%CuO+20%CeO{sub 2} (CuCeAl) were under the investigation. Physico-chemical characteristics of the catalysts were determined by the methods of BET, X-ray Diffraction (XRD), and Temperature-Programmed Reduction (TPR). A strong interaction of copper with support in CuAl resulted in the formation of low active copper aluminates. The bi-oxide CuCrAl was more active than CuAl owing to the formation of high catalytically active spinel CuCr{sub 2}O{sub 4}. The fact of very high activity of the sample CuCeAl can be explained by the presence of the catalytically active form of CuO-CeO{sub 2}-Al{sub 2}O{sub 3}. The kinetics of CO total oxidation was studied in a gradientless flow-circulating system at the temperature range between 200 C and 270 C. The values of initial partial pressures of carbon monoxide (P{sup o}{sub CO}), oxygen (P{sup o}{sub O2}), and specially added carbon dioxide (P{sup o}{sub CO{sub 2}}) were varied in ranges (hPa): 10 / 45; 33 / 100, and 0 / 30, respectively. (orig.)

  15. REFORMULATION OF COAL-DERIVED TRANSPORTATION FUELS: SELECTIVE OXIDATION OF CARBON MONOXIDE ON METAL FOAM CATALYSTS

    Energy Technology Data Exchange (ETDEWEB)

    Mr. Paul Chin; Dr. Xiaolei Sun; Professor George W. Roberts; Professor James J. Spivey; Mr. Amornmart Sirijarhuphan; Dr. James G. Goodwin, Jr.; Dr. Richard W. Rice

    2002-12-31

    Several different catalytic reactions must be carried out in order to convert hydrocarbons (or alcohols) into hydrogen for use as a fuel for polyelectrolyte membrane (PEM) fuel cells. Each reaction in the fuel-processing sequence has a different set of characteristics, which influences the type of catalyst support that should be used for that particular reaction. A wide range of supports are being evaluated for the various reactions in the fuel-processing scheme, including porous and non-porous particles, ceramic and metal straight-channel monoliths, and ceramic and metal monolithic foams. These different types of support have distinctly different transport characteristics. The best choice of support for a given reaction will depend on the design constraints for the system, e.g., allowable pressure drop, and on the characteristics of the reaction for which the catalyst is being designed. Three of the most important reaction characteristics are the intrinsic reaction rate, the exothermicity/endothermicity of the reaction, and the nature of the reaction network, e.g., whether more than one reaction takes place and, in the case of multiple reactions, the configuration of the network. Isotopic transient kinetic analysis was used to study the surface intermediates. The preferential oxidation of low concentrations of carbon monoxide in the presence of high concentrations of hydrogen (PROX) is an important final step in most fuel processor designs. Data on the behavior of straight-channel monoliths and foam monolith supports will be presented to illustrate some of the factors involved in choosing a support for this reaction.

  16. Copper-cerium oxides supported on carbon nanomaterial for preferential oxidation of carbon monoxide

    Institute of Scientific and Technical Information of China (English)

    高美怡; 江楠; 赵宇宏; 徐长进; 苏海全; 曾尚红

    2016-01-01

    The CuxO-CeO2/Fe@CNSs, CuxO-CeO2/MWCNTs-Co and CuxO-CeO2/MWCNTs-Ni catalysts were prepared by the im-pregnation method and characterized by transmission electron microscopy, scanning electron microscopy, X-ray powder diffrac-tion, H2-temperature programmed reduction and N2 adsorption-desorption techniques. It was found that the Fe nanoparticles were encapsulated into the multi-layered carbon nanospheres (CNSs). However, the multi-wall carbon nanotubes (MWCNTS) were generated on the Co/Al2O3 and Ni/Al2O3 precursor. The addition of carbon nanomaterial as supports could improve structural properties and low-temperature activity of the CuO-CeO2 catalyst, and save the used amount of metal catalysts in the temperature range with high selectivity for CO oxidation. The copper-cerium oxides supported on carbon nanomaterial had good resistence to H2O and CO2.

  17. A comparative study of formaldehyde and carbon monoxide complete oxidation on MnOx-CeO2 catalysts

    Institute of Scientific and Technical Information of China (English)

    LIU Xuesong; LU Jiqing; QIAN Kun; HUANG Weixin; LUO Mengfei

    2009-01-01

    MnOx-CeO2 composite catalysts were prepared by a coprecipitation method and tested for formaldehyde (HCHO) and carbon monoxide (CO) oxidation. X-ray photon spectroscopy (XPS) results indicated that the average oxidation state of surface Mn species in CeMn composite catalyst was higher compared to the pure MnOx. The enhancement of reactivity for HCHO oxidation was due to the activation of the lattice oxygen species in MnOx by the addition of CeO2, which was confirmed by the H2 temperature programmed reduction (H2-TPR) results. The remarkable enhancement of reactivity for CO oxidation by the addition of CeO2 was due to the active oxygen species generated on the CeO2 surface which directly participated in the reaction.

  18. Laboratory investigation of photochemical oxidation of organic aerosol from wood fires 2: analysis of aerosol mass spectrometer data

    Directory of Open Access Journals (Sweden)

    A. P. Grieshop

    2009-03-01

    Full Text Available Experiments were conducted to investigate the effects of photo-oxidation on organic aerosol (OA in dilute wood smoke by exposing emissions from soft- and hard-wood fires to UV light in a smog chamber. This paper focuses on changes in OA composition measured using a unit-mass-resolution quadrupole Aerosol Mass Spectrometer (AMS. The results highlight how photochemical processing can lead to considerable evolution of the mass, volatility and level of oxygenation of biomass-burning OA. Photochemical oxidation produced substantial new OA, more than doubling the OA mass after a few hours of aging under typical summertime conditions. Aging also decreased the volatility of the OA and made it progressively more oxygenated. The results also illustrate strengths of, and challenges with, using AMS data for source apportionment analysis. For example, the mass spectra of fresh and aged BBOA are distinct from fresh motor-vehicle emissions. The mass spectra of the secondary OA produced from aging wood smoke are very similar to those of the oxygenated OA (OOA that dominates ambient AMS datasets, further reinforcing the connection between OOA and OA formed from photo-chemistry. In addition, aged wood smoke spectra are similar to those from OA created by photo-oxidizing dilute diesel exhaust. This demonstrates that the OOA observed in the atmosphere can be produced by photochemical aging of dilute emissions from different types of combustion systems operating on fuels with modern or fossil carbon. Since OOA is frequently the dominant component of ambient OA, the similarity of spectra of aged emissions from different sources represents an important challenge for AMS-based source apportionment studies.

  19. Photochemical oxidation of water and reduction of polyoxometalate anions at interfaces of water with ionic liquids or diethylether

    OpenAIRE

    Bernardini, Gianluca; Wedd, Anthony G.; Zhao, Chuan; Bond, Alan M.

    2012-01-01

    Photoreduction of [P2W18O62]6-, [S2Mo18O62]4-, and [S2W18O62]4- polyoxometalate anions (POMs) and oxidation of water occurs when water–ionic liquid and water–diethylether interfaces are irradiated with white light (275–750 nm) or sunlight. The ionic liquids (ILs) employed were aprotic ([Bmim]X; Bmim = (1-butyl-3-methylimidazolium,X = BF4,PF6) and protic (DEAS = diethanolamine hydrogen sulphate; DEAP = diethanolamine hydrogen phosphate). Photochemical formation of reduced POMs at both thermody...

  20. Enzymatic AND Logic Gate with Sigmoid Response Induced by Photochemically Controlled Oxidation of the Output

    OpenAIRE

    Privman, Vladimir; Fratto, Brian E.; Zavalov, Oleksandr; Halamek, Jan; Katz, Evgeny

    2013-01-01

    We report a study of a system which involves an enzymatic cascade realizing an AND logic gate, with an added photochemical processing of the output allowing to make the gate's response sigmoid in both inputs. New functional forms are developed for quantifying the kinetics of such systems, specifically designed to model their response in terms of signal and information processing. These theoretical expressions are tested for the studied system, which also allows us to consider aspects of bioch...

  1. Advanced oxidation treatment and photochemical fate of selected antidepressant pharmaceuticals in solutions of Suwannee River humic acid

    Energy Technology Data Exchange (ETDEWEB)

    Santoke, Hanoz, E-mail: hsantoke@uci.edu [Urban Water Research Center, Department of Civil and Environmental Engineering, University of California, Irvine, Irvine, CA 92697-2175 (United States); Song, Weihua, E-mail: wsong@uci.edu [Urban Water Research Center, Department of Civil and Environmental Engineering, University of California, Irvine, Irvine, CA 92697-2175 (United States); Department of Environmental Science and Engineering, Fudan University, Shanghai, 200433 (China); Cooper, William J., E-mail: wcooper@uci.edu [Urban Water Research Center, Department of Civil and Environmental Engineering, University of California, Irvine, Irvine, CA 92697-2175 (United States); Peake, Barrie M., E-mail: bpeake@chemistry.otago.ac.nz [Chemistry Department, University of Otago, P.O. Box 56, Dunedin 9054 (New Zealand)

    2012-05-30

    Highlights: Black-Right-Pointing-Pointer We elucidate the photochemical degradation of three antidepressant pharmaceuticals. Black-Right-Pointing-Pointer Hydroxyl radical is the most significant contributor to the degradation. Black-Right-Pointing-Pointer Excited state dissolved organic matter also plays a significant role for duloxetine. Black-Right-Pointing-Pointer Tentative reaction byproducts are identified. - Abstract: Antidepressant pharmaceuticals have recently been detected at low concentrations in wastewater and surface water. This work reports studies of the direct and indirect photochemical fate and treatment by advanced oxidation of three antidepressant compounds (duloxetine, venlafaxine and bupropion) in solutions of humic acid in order to elucidate their behavior in the natural environment prior to reaching a water treatment facility and potentially entering a potable water supply. Humic acid solution was prepared by adding to distilled water a known amount of organic matter as a photosensitizer. All three antidepressants react very rapidly with hydroxyl radicals ({center_dot}OH) and hydrated electrons (e{sup -}{sub aq}) with rate constants of {approx}10{sup 8} to 10{sup 10} M{sup -1} s{sup -1}, but significantly slower with singlet oxygen ({sup 1}{Delta}O{sub 2}) ({approx}10{sup 3} to 10{sup 5} M{sup -1} s{sup -1}). The steady-state concentrations of {center_dot}OH and {sup 1}{Delta}O{sub 2}, in a sample of humic acid solution were measured and used with the second order rate constants to show that the hydroxyl radical was an order of magnitude more effective than the singlet oxygen in the solar-induced photochemical degradation of the antidepressants. Excited state dissolved organic matter also accounted for a substantial portion of degradation of duloxetine, decreasing its half-life by 27% under solar irradiation. Several reaction pathways and by-products arising from the photodegradation were identified using gamma-irradiation followed by LC

  2. Photochemical Oxidative Cyclisation of Stilbenes and Stilbenoids—The Mallory-Reaction

    Directory of Open Access Journals (Sweden)

    Kåre B. Jørgensen

    2010-06-01

    Full Text Available After Mallory described in 1964 the use of iodine as catalyst for the photochemical cyclisation of stilbenes, this reaction has proven its effectiveness in the synthesis of phenanthrenes, other PAHs and phenacenes with a surprisingly large selection of substituents. The “early age” of the reaction was reviewed by Mallory in 1984in a huge chapter in the Organic Reactions series, but the development has continued. Alternative conditions accommodate more sensitive substituents, and isomers can be favoured by sacrificial substituents. Herein the further developments and applications of this reaction after 1984 are discussed and summarized.

  3. Enzymatic AND logic gate with sigmoid response induced by photochemically controlled oxidation of the output.

    Science.gov (United States)

    Privman, Vladimir; Fratto, Brian E; Zavalov, Oleksandr; Halámek, Jan; Katz, Evgeny

    2013-06-27

    We report a study of a system which involves an enzymatic cascade realizing an AND logic gate, with an added photochemical processing of the output, allowing the gate's response to be made sigmoid in both inputs. New functional forms are developed for quantifying the kinetics of such systems, specifically designed to model their response in terms of signal and information processing. These theoretical expressions are tested for the studied system, which also allows us to consider aspects of biochemical information processing such as noise transmission properties and control of timing of the chemical and physical steps.

  4. Laboratory investigation of photochemical oxidation of organic aerosol from wood fires 1: measurement and simulation of organic aerosol evolution

    Directory of Open Access Journals (Sweden)

    A. P. Grieshop

    2009-02-01

    Full Text Available Experiments were conducted to investigate the effects of photo-oxidation on organic aerosol (OA emissions from flaming and smoldering hard- and soft-wood fires under plume-like conditions. This was done by exposing the dilute emissions from a small wood stove to UV light in a smog chamber and measuring the gas- and particle-phase pollutant concentrations with a suite of instruments including a Proton Transfer Reaction Mass Spectrometer (PTR-MS, an Aerosol Mass Spectrometer (AMS and a thermodenuder. The measurements highlight how atmospheric processing can lead to considerable evolution of the mass and volatility of biomass-burning OA. Photochemical oxidation produced substantial new OA, increasing concentrations by a factor of 1.5 to 2.8 after several hours of exposure to typical summertime hydroxyl radical (OH concentrations. Less than 20% of this new OA could be explained using a state-of-the-art secondary organic aerosol model and the measured decay of traditional SOA precursors. The thermodenuder data indicate that the primary OA is semivolatile; at 50°C between 50 and 80% of the fresh primary OA evaporated. Aging reduced the volatility of the OA; at 50°C only 20 to 40% of aged OA evaporated. The predictions of a volatility basis-set model that explicitly tracks the partitioning and aging of low-volatility organics was compared to the chamber data. The OA production can be explained by the oxidation of low-volatility organic vapors; the model can also reproduce observed changes in OA volatility and composition. The model was used to investigate the competition between photochemical processing and dilution on OA concentrations in plumes.

  5. DFT studies on the SCR reaction mechanism of nitrogen monoxide with propylene catalyzed by copper oxide

    Institute of Scientific and Technical Information of China (English)

    TIAN Ying; XU Jing; ZHAO Jing-xiang

    2007-01-01

    The SCR reaction mechanism of NO with C3H6catalyzed by CuO was studied by the method of Density Functional Theory (DFT) at the B3LYP/LanL2DZ levels. The optimized geometries of the stationary points on the potential surface were obtained and the transition state was confirmed by IRC and vibration analysis. The activation energy was calculated being 34. 26 kJ/mol. It was shown that propylene reacted firstly with Cu forming intermediate, and then nitrogen monoxide immediately reacted with the intermediate to be reduced. It was proved to be a direct interaction mechanism.

  6. Carbon monoxide, skeletal muscle oxidative stress, and mitochondrial biogenesis in humans

    OpenAIRE

    Rhodes, Michael A.; Carraway, Martha Sue; Piantadosi, Claude A.; Reynolds, Crystal M; Cherry, Anne D.; Wester, T. E.; Natoli, Michael J.; Massey, E. Wayne; Moon, Richard E.; Suliman, Hagir B.

    2009-01-01

    Given that the physiology of heme oxygenase-1 (HO-1) encompasses mitochondrial biogenesis, we tested the hypothesis that the HO-1 product, carbon monoxide (CO), activates mitochondrial biogenesis in skeletal muscle and enhances maximal oxygen uptake (V̇o2max) in humans. In 10 healthy subjects, we biopsied the vastus lateralis and performed V̇o2max tests followed by blinded randomization to air or CO breathing (1 h/day at 100 parts/million for 5 days), a contralateral muscle biopsy on day 5, a...

  7. Oxidative decomposition of atrazine in water in the presence of hydrogen peroxide using an innovative microwave photochemical reactor

    Energy Technology Data Exchange (ETDEWEB)

    Chen Huilun [Department of Environmental Engineering, Civil and Environment Engineering School, University of Science and Technology Beijing, 30 Xueyuan Road, Haidian District, Beijing 100083 (China); Italian National Research Council-Istituto di Chimica dei Composti Organometallici (ICCOM), Via G. Moruzzi 1, 56124 Pisa (Italy); Bramanti, Emilia, E-mail: ebramanti@iccom.cnr.it [Italian National Research Council-Istituto di Chimica dei Composti Organometallici (ICCOM), Via G. Moruzzi 1, 56124 Pisa (Italy); Longo, Iginio [Italian National Research Council-National Institute of Optics (INO), Via G. Moruzzi 1, 56124 Pisa (Italy); Onor, Massimo [Italian National Research Council-Istituto di Chimica dei Composti Organometallici (ICCOM), Via G. Moruzzi 1, 56124 Pisa (Italy); Ferrari, Carlo [Italian National Research Council-National Institute of Optics (INO), Via G. Moruzzi 1, 56124 Pisa (Italy)

    2011-02-28

    The simultaneous application of microwave (MW) power and UV light leads to improved results in photochemical processes. This study investigates the oxidative decomposition of atrazine in water using an innovative MW and UV photochemical reactor, which activates a chemical reaction with MW and UV radiation using an immersed source without the need for a MW oven. We investigated the influence of reaction parameters such as initial H{sub 2}O{sub 2} concentrations, reaction temperatures and applied MW power and identified the optimal conditions for the oxidative decomposition of atrazine. Atrazine was completely degraded by MW/UV/H{sub 2}O{sub 2} in a very short time (i.e. t{sub 1/2} = 1.1 min for 20.8 mg/L in optimal conditions). From the kinetic study, the disappearance rate of atrazine can be expressed as dX/dt = k{sub PH}[M]{sub 0}(b - X)(1 - X), where b {identical_to} [H{sub 2}O{sub 2}]{sub 0}/[M]{sub 0} + k{sub OH}[{center_dot}OH]/k{sub PH}[M]{sub 0}, and X is the atrazine conversion, which correlates well with the experimental data. The kinetic analysis also showed that an indirect reaction of atrazine with an OH radical is dominant at low concentrations of H{sub 2}O{sub 2} and a direct reaction of atrazine with H{sub 2}O{sub 2} is dominant when the concentration of H{sub 2}O{sub 2} is more than 200 mg/L.

  8. Surface composition tuning of Au-Pt bimetallic nanoparticles for enhanced carbon monoxide and methanol electro-oxidation.

    Science.gov (United States)

    Suntivich, Jin; Xu, Zhichuan; Carlton, Christopher E; Kim, Junhyung; Han, Binghong; Lee, Seung Woo; Bonnet, Nicéphore; Marzari, Nicola; Allard, Lawrence F; Gasteiger, Hubert A; Hamad-Schifferli, Kimberly; Shao-Horn, Yang

    2013-05-29

    The ability to direct bimetallic nanoparticles to express desirable surface composition is a crucial step toward effective heterogeneous catalysis, sensing, and bionanotechnology applications. Here we report surface composition tuning of bimetallic Au-Pt electrocatalysts for carbon monoxide and methanol oxidation reactions. We establish a direct correlation between the surface composition of Au-Pt nanoparticles and their catalytic activities. We find that the intrinsic activities of Au-Pt nanoparticles with the same bulk composition of Au0.5Pt0.5 can be enhanced by orders of magnitude by simply controlling the surface composition. We attribute this enhancement to the weakened CO binding on Pt in discrete Pt or Pt-rich clusters surrounded by surface Au atoms. Our finding demonstrates the importance of surface composition control at the nanoscale in harnessing the true electrocatalytic potential of bimetallic nanoparticles and opens up strategies for the development of highly active bimetallic nanoparticles for electrochemical energy conversion.

  9. Aqueous-phase photochemical oxidation and direct photolysis of vanillin - a model compound of methoxy-phenols from biomass burning

    Science.gov (United States)

    Li, Y. J.; Huang, D. D.; Cheung, H. Y.; Lee, A. K. Y.; Chan, C. K.

    2013-10-01

    We present here experimental results on aqueous-phase (A) photochemical oxidation (with UV and OH radicals generated from H2O2 photolysis) and (B) direct photolysis (with only UV irradiation) of a methoxy-phenol, vanillin (VL), as a model compound from biomass burning. Both on-line aerosol mass spectrometric (AMS) characterization and off-line chemical analyses were performed. AMS analyses of dried atomized droplets of the bulk reacting mixtures showed that VL almost entirely evaporates during the drying process. Large amounts of organic mass remained in the particle phase after reactions under both conditions. Under condition (A), AMS measured organic mass first increased rapidly and then decreased, attributable to the formation of non-volatile products and subsequent formation of smaller and volatile products, respectively. The oxygen-to-carbon (O:C) ratio of the products reached 1.5 after about 80 min, but dropped substantially thereafter. In contrast, organic mass increased slowly under condition (B). The O:C ratio reached 1.0 after 180 min. In off-line analyses, small oxygenates were detected under condition (A), while hydroxylated products and dimers of VL were detected under condition (B). Particle hygroscopic growth factor (GF) and cloud condensation nuclei (CCN) activity of the reacting mixtures were found to be dependent on both organic volume fraction and the degree of oxygenation of organics. Results show that (1) aqueous-phase processes can lead to the retention of a large portion of the organic mass in the particle phase; (2) once retained, this portion of organic mass significantly changes the hygroscopicity and CCN activity of the aerosol particles; (3) intensive photochemical oxidation gave rise to an O:C ratio as high as 1.5 but the ratio decreased as further oxidation led to smaller and more volatile products; and (4) polymerization occurred with direct photolysis, resulting in high-molecular-weight products of a yellowish color. This study

  10. Aqueous-phase photochemical oxidation and direct photolysis of vanillin - a model compound of methoxy phenols from biomass burning

    Science.gov (United States)

    Li, Y. J.; Huang, D. D.; Cheung, H. Y.; Lee, A. K. Y.; Chan, C. K.

    2014-03-01

    We present here experimental results on aqueous-phase (A) photochemical oxidation (with UV and OH radicals generated from H2O2 photolysis) and (B) direct photolysis (with only UV irradiation) of a methoxy phenol, vanillin (VL), as a model compound from biomass burning. Both on-line aerosol mass spectrometric (AMS) characterization and off-line chemical analyses were performed. AMS analyses of dried atomized droplets of the bulk reacting mixtures showed that VL almost entirely evaporates during the drying process. Large amounts of organic mass remained in the particle phase after reactions under both conditions. Under condition (A), AMS measured organic mass first increased rapidly and then decreased, attributable to the formation of non-volatile products and subsequent formation of smaller and volatile products, respectively. The oxygen-to-carbon (O : C) ratio of the products reached 1.5 after about 80 min, but dropped substantially thereafter. In contrast, organic mass increased slowly under condition (B). The O : C ratio reached 1.0 after 180 min. In off-line analyses, small oxygenates were detected under condition (A), while hydroxylated products and dimers of VL were detected under condition (B). Particle hygroscopic growth factor (GF) and cloud condensation nuclei (CCN) activity of the reacting mixtures were found to depend on both organic volume fraction and the degree of oxygenation of organics. Results show that (1) aqueous-phase processes can lead to the retention of a large portion of the organic mass in the particle phase; (2) once retained, this portion of organic mass significantly changes the hygroscopicity and CCN activity of the aerosol particles; (3) intensive photochemical oxidation gave rise to an O : C ratio as high as 1.5 but the ratio decreased as further oxidation led to smaller and more volatile products; and (4) polymerization occurred with direct photolysis, resulting in high-molecular-weight products of a yellowish color. This study

  11. Carbon monoxide alleviates ethanol-induced oxidative damage and inflammatory stress through activating p38 MAPK pathway

    Energy Technology Data Exchange (ETDEWEB)

    Li, Yanyan; Gao, Chao; Shi, Yanru; Tang, Yuhan; Liu, Liang; Xiong, Ting; Du, Min [Department of Nutrition and Food Hygiene, School of Public Health, Tongji Medical College, Huazhong University of Science and Technology, 13 Hangkong Road, Wuhan 430030 (China); Ministry of Education Lab of Environment and Health, School of Public Health, Tongji Medical College, Huazhong University of Science and Technology, 13 Hangkong Road, Wuhan 430030 (China); Hubei Key Laboratory of Food Nutrition and Safety, School of Public Health, Tongji Medical College, Huazhong University of Science and Technology, 13 Hangkong Road, Wuhan 430030 (China); Xing, Mingyou [Department of Infectious Diseases, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, 13 Hangkong Road, Wuhan 430030 (China); Liu, Liegang [Department of Nutrition and Food Hygiene, School of Public Health, Tongji Medical College, Huazhong University of Science and Technology, 13 Hangkong Road, Wuhan 430030 (China); Ministry of Education Lab of Environment and Health, School of Public Health, Tongji Medical College, Huazhong University of Science and Technology, 13 Hangkong Road, Wuhan 430030 (China); Hubei Key Laboratory of Food Nutrition and Safety, School of Public Health, Tongji Medical College, Huazhong University of Science and Technology, 13 Hangkong Road, Wuhan 430030 (China); Yao, Ping, E-mail: yaoping@mails.tjmu.edu.cn [Department of Nutrition and Food Hygiene, School of Public Health, Tongji Medical College, Huazhong University of Science and Technology, 13 Hangkong Road, Wuhan 430030 (China); Ministry of Education Lab of Environment and Health, School of Public Health, Tongji Medical College, Huazhong University of Science and Technology, 13 Hangkong Road, Wuhan 430030 (China); Hubei Key Laboratory of Food Nutrition and Safety, School of Public Health, Tongji Medical College, Huazhong University of Science and Technology, 13 Hangkong Road, Wuhan 430030 (China)

    2013-11-15

    Stress-inducible protein heme oxygenase-1(HO-1) is well-appreciative to counteract oxidative damage and inflammatory stress involving the pathogenesis of alcoholic liver diseases (ALD). The potential role and signaling pathways of HO-1 metabolite carbon monoxide (CO), however, still remained unclear. To explore the precise mechanisms, ethanol-dosed adult male Balb/c mice (5.0 g/kg.bw.) or ethanol-incubated primary rat hepatocytes (100 mmol/L) were pretreated by tricarbonyldichlororuthenium (II) dimmer (CORM-2, 8 mg/kg for mice or 20 μmol/L for hepatocytes), as well as other pharmacological reagents. Our data showed that CO released from HO-1 induction by quercetin prevented ethanol-derived oxidative injury, which was abolished by CO scavenger hemoglobin. The protection was mimicked by CORM-2 with the attenuation of GSH depletion, SOD inactivation, MDA overproduction, and the leakage of AST, ALT or LDH in serum and culture medium induced by ethanol. Moreover, CORM-2 injection or incubation stimulated p38 phosphorylation and suppressed abnormal Tnfa and IL-6, accompanying the alleviation of redox imbalance induced by ethanol and aggravated by inflammatory factors. The protective role of CORM-2 was abolished by SB203580 (p38 inhibitor) but not by PD98059 (ERK inhibitor) or SP600125 (JNK inhibitor). Thus, HO-1 released CO prevented ethanol-elicited hepatic oxidative damage and inflammatory stress through activating p38 MAPK pathway, suggesting a potential therapeutic role of gaseous signal molecule on ALD induced by naturally occurring phytochemicals. - Highlights: • CO alleviated ethanol-derived liver oxidative and inflammatory stress in mice. • CO eased ethanol and inflammatory factor-induced oxidative damage in hepatocytes. • The p38 MAPK is a key signaling mechanism for the protective function of CO in ALD.

  12. Photochemical oxidation of thiophene by O2 in an oil/acetonitrile two-phase extraction system.

    Science.gov (United States)

    Li, Fa-Tang; Zhao, Di-Shun; Li, Hong-Xia; Liu, Rui-Hong

    2008-10-01

    Photochemical oxidation of thiophene in an n-octane/acetonitrile extraction system using O(2) as oxidant was studied. Results obtained here can be used as a reference for desulfurization of gasoline, because thiophene is one of the main components containing sulfur in fluid catalytic cracking gasoline. A 500-W high-pressure mercury lamp was used as a light source for irradiation, and air was introduced by a gas pump to supply O(2). Thiophene dissolved in nopolar n-octane solvent was photodecomposed and removed into the polar acetonitrile phase. The desulfurization rate of thiophene in n-octane was 65.2% under photoirradiation for 5 h under the conditions of air flow at 150 mL min(-1), and V(n-octane):V(acetonitrile) = 1:1. This can be improved to 96.5% by adding 0.15 g Na-ZSM-5 zeolite into the 100-mL reaction system, which is the absorbent for O(2) and thiophene. Under such conditions, the photooxidation kinetics of thiophene with O(2) and Na-ZSM-5 zeolite is first-order with an apparent rate constant of 0.6297 h(-1) and half-time of 1.10 h. The sulfur content can be reduced from 800 microL L(-1) to 28 microL L(-1).

  13. Low-Temperature Photochemically Activated Amorphous Indium-Gallium-Zinc Oxide for Highly Stable Room-Temperature Gas Sensors.

    Science.gov (United States)

    Jaisutti, Rawat; Kim, Jaeyoung; Park, Sung Kyu; Kim, Yong-Hoon

    2016-08-10

    We report on highly stable amorphous indium-gallium-zinc oxide (IGZO) gas sensors for ultraviolet (UV)-activated room-temperature detection of volatile organic compounds (VOCs). The IGZO sensors fabricated by a low-temperature photochemical activation process and exhibiting two orders higher photocurrent compared to conventional zinc oxide sensors, allowed high gas sensitivity against various VOCs even at room temperature. From a systematic analysis, it was found that by increasing the UV intensity, the gas sensitivity, response time, and recovery behavior of an IGZO sensor were strongly enhanced. In particular, under an UV intensity of 30 mW cm(-2), the IGZO sensor exhibited gas sensitivity, response time and recovery time of 37%, 37 and 53 s, respectively, against 750 ppm concentration of acetone gas. Moreover, the IGZO gas sensor had an excellent long-term stability showing around 6% variation in gas sensitivity over 70 days. These results strongly support a conclusion that a low-temperature solution-processed amorphous IGZO film can serve as a good candidate for room-temperature VOCs sensors for emerging wearable electronics.

  14. Photophysical and photochemical effects of UV and VUV photo-oxidation and photolysis on PET and PEN

    Science.gov (United States)

    Morgan, Andrew

    Polyethylene Terephthalate (PET) is a widely used polymer in the bottling, packaging, and clothing industry. In recent years an increasing global demand for PET has taken place due to the Solar Disinfection (SODIS) process. SODIS is a method of sterilizing fresh water into drinkable water. The PET bottles are used in the process to contain the water during solar irradiation due to its highly transparent optical property. Alongside PET, polyethylene 2,6-napthalate (PEN) is used in bottling and flexible electronic applications. The surface of PEN would need to be modified to control the hydrophilicity and the interaction it exudes as a substrate. The UV light absorption properties of PET and PEN are of great importance for many applications, and thus needs to be studied along with its photochemical resistance. The optical and chemical nature of PET was studied as it was treated by UV photo-oxidation, photo-ozonation, and photolysis under atmospheric pressure. Another investigation was also used to study PEN and PET as they are treated by vacuum UV (VUV) photo-oxidation, VUV photolysis, and remote oxygen reactions. The extent of the photoreactions' effect into the depth of the polymers is examined as treatment conditions are changed. The different experimental methods established the rate of several competing photoreactions on PET and PEN during irradiance, and their effect on the optical quality of the polymers.

  15. Mercury in Arctic snow: Quantifying the kinetics of photochemical oxidation and reduction

    Energy Technology Data Exchange (ETDEWEB)

    Mann, E.A. [Department of Environmental Science, Acadia University, Wolfville, NS (Canada); Environmental Science Programme, Memorial University of Newfoundland, St. John' s, NL (Canada); Mallory, M.L. [Department of Biology, Acadia University, Wolfville, NS (Canada); Ziegler, S.E. [Environmental Science Programme, Memorial University of Newfoundland, St. John' s, NL (Canada); Tordon, R. [Environment Canada, Dartmouth, NS (Canada); O' Driscoll, N.J., E-mail: nelson.odriscoll@acadiau.ca [Department of Environmental Science, Acadia University, Wolfville, NS (Canada)

    2015-03-15

    Controlled experiments were performed with frozen and melted Arctic snow to quantify relationships between mercury photoreaction kinetics, ultra violet (UV) radiation intensity, and snow ion concentrations. Frozen (− 10 °C) and melted (4 °C) snow samples from three Arctic sites were exposed to UV (280–400 nm) radiation (1.26–5.78 W · m{sup −2}), and a parabolic relationship was found between reduction rate constants in frozen and melted snow with increasing UV intensity. Total photoreduced mercury in frozen and melted snow increased linearly with greater UV intensity. Snow with the highest concentrations of chloride and iron had larger photoreduction and photooxidation rate constants, while also having the lowest Hg(0) production. Our results indicate that the amount of mercury photoreduction (loss from snow) is the highest at high UV radiation intensities, while the fastest rates of mercury photoreduction occurred at both low and high intensities. This suggests that, assuming all else is equal, earlier Arctic snow melt periods (when UV intensities are less intense) may result in less mercury loss to the atmosphere by photoreduction and flux, since less Hg(0) is photoproduced at lower UV intensities, thereby resulting in potentially greater mercury transport to aquatic systems with snowmelt. - Highlights: • Mercury photochemical kinetics were studied in frozen and melted Arctic snow. • UV-induced photoreduction and photooxidation rate constants were quantified. • Chloride ion, iron, and DOC influence mercury photoreactions in snow. • Frozen and melted snow have different mercury photoreduction characteristics. • Kinetic information provided can be used to model mercury fate in the Arctic.

  16. Concentrations of Carbon Monoxide and Nitrogen Oxides From a 25 kW Boiler Supplied Periodically and Continuously with Wood Pellets

    Directory of Open Access Journals (Sweden)

    Juszczak Marek

    2014-06-01

    Full Text Available The impact of the fuel feeding mode (continuous or periodic with different stand-by/operation time ratios on carbon monoxide (CO and nitrogen oxides (NO, NOx concentration values in the flue gas was analysed for coniferous wood pellet firing. Experiments were performed in a 25 kW water boiler equipped with an over-fed wood pellet furnace located in a full scale heat station simulating real-life conditions. Influence of oxygen concentration and temperature in the combustion chamber on carbon monoxide and nitrogen oxide concentrations was presented in diagrams. Dust and hydrocarbon concentrations were also monitored. It was concluded that the commonly used periodic fuel supply does not necessarily cause a significant increase of carbon monoxide concentration, as compared to the continuous fuel feeding mode. Continuous fuel supply can even induce higher carbon monoxide concentrations when fuel mass stream is not chosen properly. Each time new fuel type is used in a specific furnace, one should perform experiments to determine the adequate settings (stand-by/operation time ratio, fuel mass streams, air stream to obtain the optimal, lowest possible emission for a certain boiler heat output

  17. Carbon monoxide oxidation on Pt single crystal electrodes: understanding the catalysis for low temperature fuel cells.

    Science.gov (United States)

    García, Gonzalo; Koper, Marc T M

    2011-08-01

    Herein the general concepts of fuel cells are discussed, with special attention to low temperature fuel cells working in alkaline media. Alkaline low temperature fuel cells could well be one of the energy sources in the next future. This technology has the potential to provide power to portable devices, transportation and stationary sectors. With the aim to solve the principal catalytic problems at the anode of low temperature fuel cells, a fundamental study of the mechanism and kinetics of carbon monoxide as well as water dissociation on stepped platinum surfaces in alkaline medium is discussed and compared with those in acidic media. Furthermore, cations involved as promoters for catalytic surface reactions are also considered. Therefore, the aim of the present work is not only to provide the new fundamental advances in the electrocatalysis field, but also to understand the reactions occurring at fuel cell catalysts, which may help to improve the fabrication of novel electrodes in order to enhance the performance and to decrease the cost of low temperature fuel cells.

  18. Oxidation of Carbon Monoxide over Cu/CeO2 Catalysts Prepared by SMAI

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    Supported Cu catalysts for low-temperature CO oxidation were prepared by solvated metal atom impregnation (SMAI). X-ray photoelectron spectroscopy (XPS) investigations indicated that the copper in all the samples was in a metallic state. XRD measurements showed that the mean diameters of Cu particles prepared by SMAI were small. Catalytical tests showed that the SMAI catalyst had high CO oxidation activity.

  19. Photochemical oxidation of chloride ion by ozone in acid aqueous solution.

    Science.gov (United States)

    Levanov, Alexander V; Isaykina, Oksana Ya; Amirova, Nazrin K; Antipenko, Ewald E; Lunin, Valerii V

    2015-11-01

    The experimental investigation of chloride ion oxidation under the action of ozone and ultraviolet radiation with wavelength 254 nm in the bulk of acid aqueous solution at pH 0-2 has been performed. Processes of chloride oxidation in these conditions are the same as the chemical reactions in the system O3 - OH - Cl(-)(aq). Despite its importance in the environment and for ozone-based water treatment, this reaction system has not been previously investigated in the bulk solution. The end products are chlorate ion ClO3(-) and molecular chlorine Cl2. The ions of trivalent iron have been shown to be catalysts of Cl(-) oxidation. The dependencies of the products formation rates on the concentrations of O3 and H(+) have been studied. The chemical mechanism of Cl(-) oxidation and Cl2 emission and ClO3(-) formation has been proposed. According to the mechanism, the dominant primary process of chloride oxidation represents the complex interaction with hydroxyl radical OH with the formation of Cl2(-) anion-radical intermediate. OH radical is generated on ozone photolysis in aqueous solution. The key subsequent processes are the reactions Cl2(-) + O3 → ClO + O2 + Cl(-) and ClO + H2O2 → HOCl + HO2. Until the present time, they have not been taken into consideration on mechanistic description and modelling of Cl(-) oxidation. The final products are formed via the reactions 2ClO → Cl2O2, Cl2O2 + H2O → 2H(+) + Cl(-) + ClO3(-) and HOCl + H(+) + Cl(-) ⇄ H2O + Cl2. Some portion of chloride is oxidized directly by O3 molecule with the formation of molecular chlorine in the end.

  20. Molecular composition and volatility of isoprene photochemical oxidation secondary organic aerosol under low and high NOx conditions

    Energy Technology Data Exchange (ETDEWEB)

    D' Ambro, Emma; Lee, Ben H.; Liu, Jiumeng; Shilling, John E.; Gaston, Cassandra J.; Lopez-Hilfiker, Felipe D.; Schobesberger, Siegfried; Zaveri, Rahul A.; Mohr, Claudia; Lutz, Anna; Zhang, Zhenfa; Gold, Avram; Surratt, Jason D.; Rivera-Rios, Jean; Keutsch, Frank N.; Thornton, Joel A.

    2017-01-04

    We present measurements of secondary organic aerosol (SOA) formation from isoprene photochemical oxidation formed in an environmental simulation chamber using dry neutral seed particles, thereby suppressing the role of acid catalyzed multiphase chemistry, at a variety of oxidant conditions. A high-resolution time-of-flight chemical ionization mass spectrometer (HRToF-CIMS) utilizing iodide-adduct ionization coupled to the Filter Inlet for Gases and AEROsols (FIGAERO) allowed for the simultaneous online sampling of the gas and particle composition. Under high HO2 and low NO conditions, highly oxygenated (O:C ≥ 1) C5 compounds were major components (~50%) of the SOA. The overall composition of the SOA evolved both as a function of time and as a function of input NO concentrations. As the level of input NO increased, organic nitrates increased in both the gas- and particle-phases, but the dominant non-nitrate particle-phase components monotonically decreased. We use comparisons of measured and predicted gas-particle partitioning of individual components to assess the validity of literature-based group-contribution methods for estimating saturation vapor concentrations. While there is evidence for equilibrium partitioning being achieved on the chamber residence time scale (5.2 hours) for some individual components, significant errors in group-contribution methods are revealed. In addition, >30% of the SOA mass, detected as low-molecular weight compounds, cannot be reconciled with equilibrium partitioning. These compounds desorb from the FIGAERO at unexpectedly high temperatures given their molecular composition, indicative of thermal decomposition of effectively lower volatility components, likely larger molecular weight oligomers. We use these insights from the laboratory and observations of the same SOA components made during the Southern Oxidant and Aerosol Study (SOAS) to assess the importance of isoprene photooxidation as a local SOA source.

  1. Carbon monoxide, skeletal muscle oxidative stress, and mitochondrial biogenesis in humans.

    Science.gov (United States)

    Rhodes, Michael A; Carraway, Martha Sue; Piantadosi, Claude A; Reynolds, Crystal M; Cherry, Anne D; Wester, T E; Natoli, Michael J; Massey, E Wayne; Moon, Richard E; Suliman, Hagir B

    2009-07-01

    Given that the physiology of heme oxygenase-1 (HO-1) encompasses mitochondrial biogenesis, we tested the hypothesis that the HO-1 product, carbon monoxide (CO), activates mitochondrial biogenesis in skeletal muscle and enhances maximal oxygen uptake (Vo(2max)) in humans. In 10 healthy subjects, we biopsied the vastus lateralis and performed Vo(2max) tests followed by blinded randomization to air or CO breathing (1 h/day at 100 parts/million for 5 days), a contralateral muscle biopsy on day 5, and repeat Vo(2max) testing on day 8. Six independent subjects underwent CO breathing and two muscle biopsies without exercise testing. Molecular studies were performed by real-time RT-PCR, Western blot analysis, and immunochemistry. After Vo(2max) testing plus CO breathing, significant increases were found in mRNA levels for nuclear respiratory factor-1, peroxisome proliferator-activated receptor-gamma coactivator-1alpha, mitochondrial transcription factor-A (Tfam), and DNA polymerase gamma (Polgamma) with no change in mitochondrial DNA (mtDNA) copy number or Vo(2max). Levels of myosin heavy chain I and nuclear-encoded HO-1, superoxide dismutase-2, citrate synthase, mitofusin-1 and -2, and mitochondrial-encoded cytochrome oxidase subunit-I (COX-I) and ATPase-6 proteins increased significantly. None of these responses were reproduced by Vo(2max) testing alone, whereas CO alone increased Tfam and Polgamma mRNA, and COX-I, ATPase-6, mitofusin-2, HO-1, and superoxide dismutase protein. These findings provide evidence linking the HO/CO response involved in mitochondrial biogenesis in rodents to skeletal muscle in humans through a set of responses involving regulation of the mtDNA transcriptosome and mitochondrial fusion proteins autonomously of changes in exercise capacity.

  2. CuO/CeO2 Catalysts for Selective Oxidation of Carbon Monoxide in Excess Hydrogen

    Institute of Scientific and Technical Information of China (English)

    刘春涛; 史鹏飞; 张菊香

    2004-01-01

    CuO/CeO2 catalysts were prepared by a coprecipitation method and tested for CO removal from reformed fuels via selective oxidation. The influence of the calcination temperature on the chemical compositions and catalytic performance of CuO/CeO2 catalysts were studied. It was found that CuO/CeO2 catalysts exhibit excellent CO oxidation activity and selectivity,and the complete removal of CO is attained when the catalysts are calcined at appropriate temperatures. XRD, TPR and XPS results indicate that CuO/CeO2 catalysts exhibit higher catalytic performance in CO selective oxidation due to the strong interaction between copper oxide and cerium dioxide, which promotes the dispersion and hydrogen reduction activity of copper.

  3. De-etiolation of wheat seedling leaves: cross talk between heme oxygenase/carbon monoxide and nitric oxide.

    Directory of Open Access Journals (Sweden)

    Yahui Liu

    Full Text Available Greening of etiolated plants is predominantly stimulated by light but the complete molecular mechanism is still unknown. Multiple studies currently focus on the important physiological effects of heme oxygenase (HO/carbon monoxide (CO in plants. In this report, firstly, the role of HO/CO in light-induced de-etiolation process was investigated. We discovered that light could significantly increase HO activities, HO-1 gene expression, CO release, and chlorophyll accumulation, all of which were sensitive to zinc protoporphyrin (ZnPPIX, the potent inhibitor of HO-1, respectively. Both HO-1 inducer hematin (H and CO aqueous solution were able to relieve etiolation in wheat seedling leaves under completely darkness by up-regulating endogenous HO/CO system, so as nitric oxide (NO donor sodium nitroprusside (SNP did. Similarly, endogenous NO production was also boost in response to light, SNP, hematin and CO aqueous solution in wheat seedling leaves. Additionally, the restoration of chlorophyll contents was blocked, when the inhibitor of mammalian nitric oxide synthase N(G-nitro-L-arginine methylester hydrochloride (L-NAME or the specific scavenger of NO 2-(4-carboxyphenyl-4, 4, 5, 5-tetramethylimidazoline-1-oxyl-3-oxide potassium salt (cPTIO was added, respectively. Furthermore, the inducible effects of light were different from those of SNP, hematin, and CO on Pfr accumulation and PHYA transcripts. However, all of sodium nitroprusside (SNP, hematin, and CO could accelerate NO emission, which suggested that HO/CO in wheat seedlings de-etiolation under dark-light transition may have a cross talk with NO.

  4. Real-Time Studies of Iron Oxalate-Mediated Oxidation of Glycolaldehyde as a Model for Photochemical Aging of Aqueous Tropospheric Aerosols

    OpenAIRE

    Thomas, Daniel A.; Coggon, Matthew M.; Lignell, Hanna; Schilling, Katherine Ann; Zhang, Xuan; Schwantes, Rebecca H.; Flagan, Richard C.; Seinfeld, John H.; Beauchamp, Jesse Lee

    2016-01-01

    The complexation of iron (III) with oxalic acid in aqueous solution yields a strongly absorbing chromophore that undergoes efficient photodissociation to give iron (II) and the carbon dioxide anion radical. Importantly, iron (III) oxalate complexes absorb near-UV radiation (λ > 350 nm), providing a potentially powerful source of oxidants in aqueous tropospheric chemistry. Although this photochemical system has been studied extensively, the mechanistic details associated with its role in the o...

  5. Kinetics of Carbon Monoxide Electro-Oxidation in Solid-Oxide Fuel Cells from Ni-YSZ Patterned-Anode Measurements

    KAUST Repository

    Hanna, J.

    2013-04-17

    A mathematical model is developed around the framework of a reduced mechanism describing electrochemical oxidation of carbon monoxide on Ni-YSZ patterned anodes. The electro-oxidation mechanism involves three reactions, one describing adsorption/ desorption of COonNi, and two single-electron charge-transfer steps inwhich the surface adsorbate CO(Ni) participates directly. These steps are coupled with surface transport in a reaction-diffusion model for which analytic equilibrium and steady-state solutions are derived. As much as possible, we make use of existing, independent, published information about heterogeneous chemistry, surface transport, and other model parameters. The only unknowns in our model are taken to be the kinetic rate constants of the electrochemical reactions, which we evaluate by fitting the model predictions to previously published patterned-anode experiments [B. Habibzadeh, Ph.D. Thesis, University of Maryland, College Park, MD, USA (2007)]. The results show that diffusion of CO on the Ni surface to the three-phase boundary is the rate-controlling process for CO electro-oxidation. Moreover, from a reaction standpoint, the charge-transfer process is dominated by a slow step involving CO(Ni). These findings collectively demonstrate the critical dependence of the electro-oxidation process to the direct participation of CO. © 2013 The Electrochemical Society. All rights reserved.

  6. Modeling of carbon monoxide oxidation kinetics over NASA carbon dioxide laser catalysts

    Science.gov (United States)

    Herz, Richard K.

    1989-01-01

    The recombination of CO and O2 formed by the dissociation of CO2 in a sealed CO2 laser discharge zone is examined. Conventional base-metal-oxide catalysts and conventional noble-metal catalysts are not effective in recombining the low O2/CO ratio at the low temperatures used by the lasers. The use of Pt/SnO2 as the noble-metal reducible-oxide (NMRO), or other related materials from Group VIIIA and IB and SnO2 interact synergistically to produce a catalytic activity that is substantially higher than either componet separately. The Pt/SnO2 and Pd/SnO2 were reported to have significant reaction rates at temperatures as low as -27 C, conditions under which conventional catalysts are inactive. The gas temperature range of lasers is 0 + or - 40 C. There are three general ways in which the NMRO composite materials can interact synergistically: one component altering the properties of another component; the two components each providing independent catalytic functions in a complex reaction mechanism; and the formation of catalytic sites through the combination of two components at the atomic level. All three of these interactions may be important in low temperature CO oxidation over NMRO catalysts. The effect of the noble metal on the oxide is discussed first, followed by the effect of the oxide on the noble metal, the interaction of the noble metal and oxide to form catalytic sites, and the possible ways in which the CO oxidation reaction is catalyzed by the NMRO materials.

  7. Oxidation of chlorfenvinphos in ultrapure and natural waters by ozonation and photochemical processes.

    Science.gov (United States)

    Acero, Juan L; Real, Francisco J; Javier Benitez, F; González, Antonio

    2008-06-01

    The chemical oxidation of the organophosphorus insecticide chlorfenvinphos, a priority pollutant in aquatic environments, has been conducted in ultrapure water, by means of single degradation agents (ozone and UV radiation), and by the Advanced Oxidation Processes constituted by combinations of these oxidants (O(3)/H(2)O(2) and UV/H(2)O(2)). The influence of the operating variables was discussed, and the degradation rates were evaluated by determining the rate constants for the reactions with ozone (k(O)(3)=3.7+/-0.2 L mol(-1)s(-1)) and OH radicals (k(OH)=(3.2+/-0.2)x10(9) L mol(-1)s(-1)), as well as the quantum yield for the photodegradation (around 0.1 mol E(-1), depending on the pH). Additionally, the ozonation of chlorfenvinphos in a natural water system (a surface water from a reservoir) was studied. The influence of the operating conditions on the insecticide removal efficiency was established, and the R(ct) parameter was evaluated. A kinetic model was proposed for the prediction of the elimination rate of chlorfenvinphos in the ozonation process and the results obtained reveal a good agreement between experimental results and predicted values.

  8. Molecular composition and volatility of isoprene photochemical oxidation secondary organic aerosol under low- and high-NOx conditions

    Science.gov (United States)

    D'Ambro, Emma L.; Lee, Ben H.; Liu, Jiumeng; Shilling, John E.; Gaston, Cassandra J.; Lopez-Hilfiker, Felipe D.; Schobesberger, Siegfried; Zaveri, Rahul A.; Mohr, Claudia; Lutz, Anna; Zhang, Zhenfa; Gold, Avram; Surratt, Jason D.; Rivera-Rios, Jean C.; Keutsch, Frank N.; Thornton, Joel A.

    2017-01-01

    We present measurements of secondary organic aerosol (SOA) formation from isoprene photochemical oxidation in an environmental simulation chamber at a variety of oxidant conditions and using dry neutral seed particles to suppress acid-catalyzed multiphase chemistry. A high-resolution time-of-flight chemical ionization mass spectrometer (HR-ToF-CIMS) utilizing iodide-adduct ionization coupled to the Filter Inlet for Gases and Aerosols (FIGAERO) allowed for simultaneous online sampling of the gas and particle composition. Under high-HO2 and low-NO conditions, highly oxygenated (O : C ≥ 1) C5 compounds were major components (˜ 50 %) of SOA. The SOA composition and effective volatility evolved both as a function of time and as a function of input NO concentrations. Organic nitrates increased in both the gas and particle phases as input NO increased, but the dominant non-nitrate particle-phase components monotonically decreased. We use comparisons of measured and predicted gas-particle partitioning of individual components to assess the validity of literature-based group-contribution methods for estimating saturation vapor concentrations. While there is evidence for equilibrium partitioning being achieved on the chamber residence timescale (5.2 h) for some individual components, significant errors in group-contribution methods are revealed. In addition, > 30 % of the SOA mass, detected as low-molecular-weight semivolatile compounds, cannot be reconciled with equilibrium partitioning. These compounds desorb from the FIGAERO at unexpectedly high temperatures given their molecular composition, which is indicative of thermal decomposition of effectively lower-volatility components such as larger molecular weight oligomers.

  9. The effect of carbon monoxide integrating nitric oxide through auxin signal in Arabidopsis to modulate iron deficiency

    Directory of Open Access Journals (Sweden)

    Liming eYang

    2016-03-01

    Full Text Available Carbon monoxide (CO and nitric oxide (NO are essential modulators that regulate the plant response to iron deficiency (-Fe. Auxin is a phytohormone that plays important roles in plant growth and development. We report here that in Arabidopsis –Fe enhanced heme oxygenase-dependent CO generation and auxin transport through redistribution of PIN1 protein, which subsequently increased NO accumulation; NO signaling regulated the activity of ferric chelate reductase (FCR and the expression of Fe-uptake genes including basic helix-loop-helix transcription factor (FIT and the ferric reduction oxidase 2 (FRO2. Over-expression of HY1 encoding heme oxygenase, or treatment with CO donor enhanced basipetal auxin transport, FCR activity, and the expressions of FIT and FRO2 under –Fe. Such effects were compromised in the mutant aux1-7 impaired in auxin transport or in the mutant noa1 or nia1/nia2 defective in NO biosynthesis. -Fe failed to promote auxin transport and FCR activity in hy1 mutant; such inability was reversed in the double mutant of hy1/yucca1 with elevated auxin production, or in hy1/cue1 mutant with NO over-accumulation. Taken together, our results suggest that CO modulates NO signaling through auxin to cope with Fe deficiency in Arabidopsis.

  10. Amperometric Microsensors Monitoring Glutamate-Evoked In Situ Responses of Nitric Oxide and Carbon Monoxide from Live Human Neuroblastoma Cells

    Directory of Open Access Journals (Sweden)

    Yejin Ha

    2017-07-01

    Full Text Available In the brain, nitric oxide (NO and carbon monoxide (CO are important signaling gases which have multifaceted roles, such as neurotransmitters, neuromodulators, and vasodilators. Even though it is difficult to measure NO and CO in a living system due to their high diffusibility and extremely low release levels, electrochemical sensors are promising tools to measure in vivo and in vitro NO and CO gases. In this paper, using amperometric dual and septuple NO/CO microsensors, real-time NO and CO changes evoked by glutamate were monitored simultaneously for human neuroblastoma (SH-SY5Y cells. In cultures, the cells were differentiated and matured into functional neurons by retinoic acid and brain-derived neurotrophic factor. When glutamate was administrated to the cells, both NO and CO increases and subsequent decreases returning to the basal levels were observed with a dual NO/CO microsensor. In order to facilitate sensor’s measurement, a flower-type septuple NO/CO microsensor was newly developed and confirmed in terms of the sensitivity and selectivity. The septuple microsensor was employed for the measurements of NO and CO changes as a function of distances from the position of glutamate injection. Our sensor measurements revealed that only functionally differentiated cells responded to glutamate and released NO and CO.

  11. Characterization of the oxygen tolerance of a hydrogenase linked to a carbon monoxide oxidation pathway in Rubrivivax gelatinosus.

    Science.gov (United States)

    Maness, Pin-Ching; Smolinski, Sharon; Dillon, Anne C; Heben, Michael J; Weaver, Paul F

    2002-06-01

    A hydrogenase linked to the carbon monoxide oxidation pathway in Rubrivivax gelatinosus displays tolerance to O2. When either whole-cell or membrane-free partially purified hydrogenase was stirred in full air (21% O2, 79% N2), its H2 evolution activity exhibited a half-life of 20 or 6 h, respectively, as determined by an anaerobic assay using reduced methyl viologen. When the partially purified hydrogenase was stirred in an atmosphere containing either 3.3 or 13% O2 for 15 min and evaluated by a hydrogen-deuterium (H-D) exchange assay, nearly 80 or 60% of its isotopic exchange rate was retained, respectively. When this enzyme suspension was subsequently returned to an anaerobic atmosphere, more than 90% of the H-D exchange activity was recovered, reflecting the reversibility of this hydrogenase toward O2 inactivation. Like most hydrogenases, the CO-linked hydrogenase was extremely sensitive to CO, with 50% inhibition occurring at 3.9 microM dissolved CO. Hydrogen production from the CO-linked hydrogenase was detected when ferredoxins of a prokaryotic source were the immediate electron mediator, provided they were photoreduced by spinach thylakoid membranes containing active water-splitting activity. Based on its appreciable tolerance to O2, potential applications of this hydrogenase are discussed.

  12. Platinum supported catalysts for carbon monoxide preferential oxidation: Study of support influence

    Energy Technology Data Exchange (ETDEWEB)

    Padilla, R.; Rodriguez, L.; Serrano-Lotina, A.; Daza, L. [Instituto de Catalisis y Petroleoquimica (CSIC), C/Marie Curie 2, Campus Cantoblanco, 28049 Madrid (Spain); Benito, M. [Instituto de Catalisis y Petroleoquimica (CSIC), C/Marie Curie 2, Campus Cantoblanco, 28049 Madrid (Spain); Centro de Investigaciones Energeticas Medioambientales y Tecnologicas (CIEMAT), Av. Complutense 22, 28040 Madrid (Spain)

    2009-07-01

    The aim of this work is to study the influence of the addition of different oxides to an alumina support, on surface acidity and platinum reducibility in platinum-based catalysts, as well as their effect on the activity and selectivity in CO preferential oxidation, in presence of hydrogen. A correlation between surface acidity and acid strength of surface sites and metal reducibility was obtained, being Pt-support interaction a function of the acid sites concentration under a particular temperature range. In platinum supported on alumina catalysts, CO oxidation follows a Langmuir-Hinshelwood mechanism, where O{sub 2} and CO compete in the adsorption on the same type of active sites. It is noteworthy that the addition of La{sub 2}O{sub 3} modifies the reaction mechanism. In this case, CO is not only adsorbed on the Pt active sites but also on La{sub 2}O{sub 3}, forming bridge bonded carbonates which leads to high reactivity at low temperatures. An increase on temperature produces CO desorption from Pt surface sites and favours oxygen adsorption producing CO{sub 2}. CO oxidation with surface hydroxyl groups was activated producing simultaneously CO{sub 2} and H{sub 2}. (author)

  13. Self-sustained carbon monoxide oxidation oscillations on size-selected platinum nanoparticles at atmospheric pressure

    DEFF Research Database (Denmark)

    Jensen, Robert; Andersen, Thomas; Nierhoff, Anders Ulrik Fregerslev

    2013-01-01

    High-quality mass spectrometry data of the oscillatory behavior of CO oxidation on SiO2 supported Pt-nanoparticles at atmospheric pressure have been acquired as a function of pressure, coverage, gas composition and nanoparticle size. The oscillations are self-sustained for several days at constant...

  14. Continuous measurements of nitrous oxide, carbon monoxide, methane and carbon dioxide in the surface ocean with novel laser-absorption analysers

    Science.gov (United States)

    Kaiser, Jan; Grefe, Imke; Wager, Natalie; Bakker, Dorothee C. E.; Lee, Gareth A.

    2013-04-01

    In recent years, improvements in spectroscopic technology have revolutionised atmospheric trace gas research. In particular, cavity-based optical absorption analysers allow determination of gas concentrations with high frequency, repeatability, reproducibility and long-term stability. These qualities make them particularly suitable for autonomous measurements on voluntary observing ships (VOS). Here, we present results from three of the first deployments of such analysers on research ships, as a first step towards VOS installations. Los Gatos off-axis ICOS (Integrated Cavity Output Spectroscopy) analysers were used to measure nitrous oxide (N2O), carbon monoxide (CO), methane (CH4) and carbon dioxide (CO2) mixing ratios in ocean surface water during research cruises in 2010, 2011 and 2012. The analysers were coupled to an equilibrator fed by the scientific seawater supply in the ship's laboratories. The equilibrator measurements were alternated with regular measurements of marine air and calibrated standard gases. Short-term precision for 10 s-average N2O mole fractions at an acquisition rate of 1 Hz was better than 0.2 nmol mol-1. The same value was achieved for duplicate measurements of a standard gas analysed within 1 hour of each other. The response time to concentration changes in water was 142-203 s, depending on the headspace flow rate. During the first deployment on the AMT20 cruise (Atlantic Meridional Transect, Southampton to Punta Arenas, 12 October to 25 November 2010), we unexpectedly found the subtropical gyres to be slightly undersaturated in N2O, implying that this region acted as a sink for this greenhouse gas. In contrast, the equatorial region was supersaturated and a source of nitrous oxide to the atmosphere. Mean sea-to-air fluxes were overall small and ranged between -1.6 and 0.11 μmol m-2 d-1 (negative fluxes imply an net uptake by the ocean). Despite the good short-term repeatability, significant calibration drift occurred between the six

  15. Measurements of hydrocarbons, oxygenated hydrocarbons, carbon monoxide, and nitrogen oxides in an urban basin in Colorado: Implications for Emission Inventories

    Science.gov (United States)

    Goldan, P. D.; Trainer, M.; Kuster, W. C.; Parrish, D. D.; Carpenter, J.; Roberts, J. M.; Yee, J. E.; Fehsenfeld, F. C.

    1995-11-01

    Concentrations of a wide variety of volatile organic compounds (VOCs) in the C3 to C10 range, CO, NOy (total reactive oxidized nitrogen), SO2, and meteorological parameters were measured concurrently at a site on the western perimeter of Boulder, Colorado, during February 1991. The measurement site, located some 150 m above the Boulder urban basin, receives air masses typifying averaged local sources. The highest hydrocarbon concentrations observed showed little effects of photochemical loss processes and reflect the pattern of the local emission sources. The observed ratios of CO and the VOCs to NOy are compared to those predicted by the 1985 National Acid Precipitation Assessment Program (NAPAP) inventory.These comparisons indicate (1) good agreement for CO/NOY, (2) significant overpredictions by the NAPAP inventory for many of the hydrocarbon to NOY ratios, (3) much more benzene from mobile sources (and less from area sources) than predicted by the NAPAP inventory, and (4) large underpredictions of the light alcohols and carbonyls by the NAPAP inventory. These first two results are in marked contrast to the conclusions of the recent tunnel study reported by Ingalls in 1989. Source profile reconciliation implies substantial input from both a local propane source and gasoline headspace venting.

  16. EFFECT OF NATURAL IRON OXIDE, HYDROGEN PEROXIDE, AND OXALIC ACID ON PHOTOCHEMICAL DEGRADATION OF 2-CHLOROPHENOL

    Directory of Open Access Journals (Sweden)

    W REMACHE

    2014-07-01

    Full Text Available The voluntary or accidental release of chemical compounds in the environment is a major cause of pollution of natural waters. Most of chlorophenols are toxic and hardly biodegradable and are difficult to remove from the environment. Therefore, it is important to find innovative and economical methods for the safe and complete destruction. The objective of this work is to test the activity photocatalytic of natural iron oxide (NIO in the photodegradation of 2-chlorophenol (2-CP. The analysis chromatographic with HPLC of solutions exposed under UV irradiation revealed that the degradation of 2-CP was negligible under the condition of using only natural iron oxide. The effect of wavelength on photoreactivity of NIO was also investigated in this process: at high wavelength thus at low energy the efficiency of degradation is important. We have also investigated the activation of NIO by hydrogen peroxide and oxalic acid, The results showed that the photodegradation of 2-CP under UVA irradiation could be enhanced greatly in the presence of oxalate. 2-CP was completly removed after 240 minutes of irradiation when the concentration of oxalic acid is equal to 2.10-3 M. The use of 2.0 % of isopropanol as a scavenger confirmed the intervention of hydroxyl radicals in the photodegradation of 2-CP.

  17. Operando atomic structure and active sites of TiO2(110)-supported gold nanoparticles during carbon monoxide oxidation.

    Science.gov (United States)

    Saint-Lager, Marie-Claire; Laoufi, Issam; Bailly, Aude

    2013-01-01

    It is well known that gold nanoparticles supported on TiO2 act as a catalyst for CO oxidation, even below room temperature. Despite extensive studies, the origin of this catalytic activity remains under debate. Indeed, when the particle size decreases, many changes may occur; thus modifying the nanoparticles' electronic properties and consequently their catalytic performances. Thanks to a state-of-the-art home-developed setup, model catalysts can be prepared in ultra-high vacuum and their morphology then studied in operando conditions by Grazing Incidence Small Angle X-ray Scattering, as well as their atomic structure by Grazing Incidence X-ray Diffraction as a function of their catalytic activity. We previously reported on the existence of a catalytic activity maximum observed for three-dimensional gold nanoparticles with a diameter of 2-3 nm and a height of 6-7 atomic planes. In the present work we correlate this size dependence of the catalytic activity to the nanoparticles' atomic structure. We show that even when their size decreases below the optimum diameter, the gold nanoparticles keep the face-centered cubic structure characteristic of bulk gold. Nevertheless, for these smallest nanoparticles, the lattice parameter presents anisotropic strains with a larger contraction in the direction perpendicular to the surface. Moreover a careful analysis of the atomic-scale morphology around the catalytic activity maximum tends to evidence the role of sites with a specific geometry at the interface between the nanoparticles and the substrate. This argues for models where atoms at the interface periphery act as catalytically active sites for carbon monoxide oxidation.

  18. Nitrogen-monoxide gas-sensing properties of transparent p-type copper-oxide nanorod arrays

    Energy Technology Data Exchange (ETDEWEB)

    Park, Soojeong; Kim, Hyojin; Kim, Dojin [Chungnam National University, Daejeon (Korea, Republic of)

    2015-01-15

    We report the nitrogen-monoxide (NO) gas-sensing properties of transparent p-type copper-oxide (CuO) nanorod arrays synthesized by using the hydrothermal method with a CuO nanoparticle seed layer deposited on a glass substrate via sputtering process. We synthesized polycrystalline CuO nanorods measuring 200 to 300 nm in length and 20 to 30 nm in diameter for three controlled molarity ratios of 1:1, 1:2 and 1:4 between copper nitrate trihydrate [Cu(NO{sub 2}){sub 2}·3H{sub 2}O] and hexamethylenetetramine (C{sub 6}H{sub 12}N{sub 4}). The crystal structures and morphologies of the synthesized CuO nanorod arrays were examined using grazing incidence X-ray diffraction and scanning electron microscopy. The gas-sensing measurements for NO gas in dry air indicated that the CuO nanorodarray-based gas sensors synthesized under hydrothermal condition at a molarity ratio of 1:2 showed the best gas sensing response to NO gas. These CuO nanorod-array gas sensors exhibited a highly sensitive response to NO gas, with a maximum sensitivity of about 650% for 10 ppm NO in dry air at an operating temperature of 100 .deg. C. These transparent p-type CuO nanorod-array gas sensors have shown a reversible and reliable response to NO gas over a range of operating temperatures. These results indicate certain potential use of p-type oxide semiconductor CuO nanorods as sensing materials for several types of gas sensors, including p - n junction gas sensors.

  19. Nanostructured Indium Oxide Coated Silicon Nanowire Arrays: A Hybrid Photothermal/Photochemical Approach to Solar Fuels.

    Science.gov (United States)

    Hoch, Laura B; O'Brien, Paul G; Jelle, Abdinoor; Sandhel, Amit; Perovic, Douglas D; Mims, Charles A; Ozin, Geoffrey A

    2016-09-27

    The field of solar fuels seeks to harness abundant solar energy by driving useful molecular transformations. Of particular interest is the photodriven conversion of greenhouse gas CO2 into carbon-based fuels and chemical feedstocks, with the ultimate goal of providing a sustainable alternative to traditional fossil fuels. Nonstoichiometric, hydroxylated indium oxide nanoparticles, denoted In2O3-x(OH)y, have been shown to function as active photocatalysts for CO2 reduction to CO via the reverse water gas shift reaction under simulated solar irradiation. However, the relatively wide band gap (2.9 eV) of indium oxide restricts the portion of the solar irradiance that can be utilized to ∼9%, and the elevated reaction temperatures required (150-190 °C) reduce the overall energy efficiency of the process. Herein we report a hybrid catalyst consisting of a vertically aligned silicon nanowire (SiNW) support evenly coated by In2O3-x(OH)y nanoparticles that utilizes the vast majority of the solar irradiance to simultaneously produce both the photogenerated charge carriers and heat required to reduce CO2 to CO at a rate of 22.0 μmol·gcat(-1)·h(-1). Further, improved light harvesting efficiency of the In2O3-x(OH)y/SiNW films due to minimized reflection losses and enhanced light trapping within the SiNW support results in a ∼6-fold increase in photocatalytic conversion rates over identical In2O3-x(OH)y films prepared on roughened glass substrates. The ability of this In2O3-x(OH)y/SiNW hybrid catalyst to perform the dual function of utilizing both light and heat energy provided by the broad-band solar irradiance to drive CO2 reduction reactions represents a general advance that is applicable to a wide range of catalysts in the field of solar fuels.

  20. Preparation of PdCu Alloy Nanocatalysts for Nitrate Hydrogenation and Carbon Monoxide Oxidation

    Directory of Open Access Journals (Sweden)

    Fan Cai

    2016-06-01

    Full Text Available Alloying Pd with Cu is important for catalytic reactions such as denitrification reaction and CO oxidation reaction, but understanding of the catalyst preparation and its correlation with the catalyst’s activity and selectivity remains elusive. Herein, we report the results of investigations of the preparation of PdCu alloy nanocatalysts using different methods and the catalytic properties of the catalysts in catalytic denitrification reaction and CO oxidation reaction. PdCu alloy nanocatalysts were prepared by conventional dry impregnation method and ligand-capping based wet chemical synthesis method, and subsequent thermochemical activation as well. The alloying characteristics depend on the bimetallic composition. PdCu/Al2O3 with a Pd/Cu ratio of 50:50 was shown to exhibit an optimized hydrogenation activity for the catalytic denitrification reaction. The catalytic activity of the PdCu catalysts was shown to be highly dependent on the support, as evidenced by the observation of an enhanced catalytic activity for CO oxidation reaction using TiO2 and CeO2 supports with high oxygen storage capacity. Implications of the results to the refinement of the preparation of the alloy nanocatalysts are also discussed.

  1. A New Insight of Graphene oxide-Fe(III) Complex Photochemical Behaviors under Visible Light Irradiation

    Science.gov (United States)

    Liu, Renlan; Zhu, Xiaoying; Chen, Baoliang

    2017-01-01

    Graphene oxide (GO) contains not only aromatic carbon lattice but also carboxyl groups which enhanced the aqueous solubility of GO. To study the transformation of GO nanosheets in natural environments, GO aqueous dispersion was mixed with Fe3+ ions to form photoactive complex. Under visible light irradiation, Fe(III) of the complex would be reduced to Fe(II) which could subsequently reduce highly toxic Cr(VI) to Cr3+. The electron of the reduction was contributed by the decarboxylation of carboxyl groups on GO and iron was acting as a catalyst during the photoreduction. On the other hand, the consumption of carboxyl groups may convert GO to rGO which are tend to aggregate since the decreased electrostatic repulsion and the increased π-π attraction. The formed Cr3+ may be electrostatically adsorbed by the rGO sheets and simultaneously precipitated with the aggregated rGO sheets, resulting the effective removal of chromium and GO nanosheets from the aqueous environment. This study may shed a light on understanding the environmental transformation of GO and guide the treatment of Cr(VI). PMID:28084446

  2. Photochemical oxidation processes for the elimination of phenyl-urea herbicides in waters.

    Science.gov (United States)

    Benitez, F Javier; Real, Francisco J; Acero, Juan L; Garcia, Carolina

    2006-11-16

    Four phenyl-urea herbicides (linuron, chlorotoluron, diuron, and isoproturon) were individually photooxidized by monochromatic UV radiation in ultra-pure aqueous solutions. The influence of pH and temperature on the photodegradation process was established, and the first-order rate constants and quantum yields were evaluated. The sequence of photodecomposition rates was: linuron>chlorotoluron>diuron>isoproturon. The simultaneous photooxidation of mixtures of the selected herbicides in several types of waters was then performed by means of UV radiation alone, and by UV radiation combined with hydrogen peroxide. The types of waters used were: ultra-pure water, a commercial mineral water, a groundwater, and a lake water. The influence of the independent variables in these processes - the presence or absence of tert-butyl alcohol, types of herbicide and waters, and concentration of hydrogen peroxide - were established and discussed. A kinetic study was performed using a competitive kinetic model that allowed various rate constants to be evaluated for each herbicide. This kinetic model allows one to predict the elimination of these phenyl-urea herbicides in contaminated waters by the oxidation systems used (UV alone and combined UV/H2O2). The herbicide concentrations predicted by this model agree well with the experimental results that were obtained.

  3. Stochastic resonance in surface catalytic oxidation of carbon monoxide induced by colored noise

    Institute of Scientific and Technical Information of China (English)

    GONG Yubing; HOU Zhonghuai; XIN Houwen

    2004-01-01

    The dynamical behavior of surface catalytic oxidation reaction of Pt(110)/CO+O2modulated by colored noise, under the condition of specific temperature, has been investigated when the partial pressure of CO gas is near the supercritical Hopf bifurcation point. By computer simulation the oscillation and stochastic resonance induced by colored noise are observed. The influences of the intensity and correlation time of colored noise on stochastic resonance are discussed. The range of sensitivity of the system to the environmental fluctuation is analyzed.

  4. REFORMULATION OF COAL-DERIVED TRANSPORTATION FUELS: SELECTIVE OXIDATION OF CARBON MONOXIDE ON METAL FOAM CATALYSTS

    Energy Technology Data Exchange (ETDEWEB)

    Paul Chin; Xiaolei Sun; George W. Roberts; Amornmart Sirijarhuphan; Sourabh Pansare; James G. Goodwin Jr; Richard W. Rice; James J. Spivey

    2005-06-01

    Hydrocarbon fuels must be reformed in a series of steps to provide hydrogen for use in proton exchange membrane fuel cells (PEMFCs). Preferential oxidation (PROX) is one method to reduce the CO concentration to less than 10 ppm in the presence of {approx}40% H{sub 2}, CO{sub 2}, and steam. This will prevent CO poisoning of the PEMFC anode. Structured supports, such as ceramic monoliths, can be used for the PROX reaction. Alternatively, metal foams offer a number of advantages over the traditional ceramic monolith.

  5. Biogenic VOC measurements during the Oxidant and Particle Photochemical Processes (OP3) above a South-East Asian tropical rainforest Campaign

    Science.gov (United States)

    Jones, Charlotte; Hopkins, James; Lee, James; Lewis, Alastair; Hamilton, Jacqueline

    2010-05-01

    We present the first ambient air speciated monoterpene measurements from the UK FGAM (Facility for Ground based Atmospheric Measrements) - York dual channel gas chromatograph system with flame ionisation detectors, alongside measurements of other biogenic volatile organic compounds (BVOCs) such as isoprene, which were made during the Oxidant and Particle Photochemical Processes above a South-East Asian tropical rainforest (OP3) campaign in Danum Valley, Borneo, in 2008. The monoterpenes measured were alpha-pinene, camphene, 3-carene, gamma-terpinene and limonene. We compare the relative concentrations and diurnal profiles of the different monoterpene species and other BVOCs such as isoprene, and analyse variability in their concentrations in light of various environmental conditions, in order to gain insight into factors which influence their emission rates, and therefore regulate their potential impact upon photochemical processes within the boundary layer. We also present regional BVOC measurements made onboard the FAAM BAE 146 aircraft over both the natural rainforest and oil palm plantations.

  6. CO Oxidation by Group 3 Metal Monoxide Cations Supported on [Fe(CO)4 ](2).

    Science.gov (United States)

    Chi, Chaoxian; Qu, Hui; Meng, Luyan; Kong, Fanchen; Luo, Mingbiao; Zhou, Mingfei

    2017-09-10

    Infrared photodissociation spectroscopy of mass-selected heteronuclear cluster anions in the form of OMFe(CO)5(-) (M=Sc, Y, La) indicates that all these anions involve an 18-electron [Fe(CO)4 ](2-) building block that is bonded with the M center through two bridged carbonyl ligands. The OLaFe(CO)5(-) anion is determined to be a CO-tagged complex involving a [Fe(CO)4 ](2-) [LaO](+) anion core. In contrast, the OYFe(CO)5(-) anion is characterized to have a [Fe(CO)4 ](2-) [Y(η(2) -CO2 )](+) structure involving a side-on bonded CO2 ligand. The CO-tagged complex and the [Fe(CO)4 ](2-) [Sc(η(2) -CO2 )](+) isomer co-exist for the OScFe(CO)5(-) anion. These observations indicate that both the ScO(+) and YO(+) cations supported on [Fe(CO)4 ](2-) are able to oxidize CO to CO2 . Theoretical analyses show that [Fe(CO)4 ](2-) coordination significantly weakens the MO(+) bond and decreases the energy gap of the interacting valence orbitals between MO(+) and CO, leading to the CO oxidation reactions being both thermodynamically exothermic and kinetically facile. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  7. Lung diffusion capacity for nitric oxide and carbon monoxide is impaired similarly following short-term graded exercise.

    Science.gov (United States)

    Zavorsky, Gerald S; Lands, Larry C

    2005-02-01

    Study aimed to determine whether short-term graded exercise affects single-breath lung diffusion capacity for nitric oxide (DLNO) and carbon monoxide (DLCO) similarly, and whether the DLNO/DLCO ratios during rest are altered post-exercise compared to pre-exercise. Eleven healthy subjects (age=29+/-6 years; weight=76.6+/-13.2 kg; height=177.9+/-13.2 cm; and maximal oxygen uptake or V(.-)(O(2max) = 52.7 +/- 9.3 ml kg(-1) min(-1))performed simultaneous single-breath DLNO and DLCO measurements at rest (inspired NO concentration=43.2+/-4.1 ppm, inspired CO concentration=0.30%) 15 min before and 2h after a graded exercise test to exhaustion (exercise duration=593+/-135 s). Resting DLNO and DLCO was similarly reduced 2h post-exercise (DLNO=-7.8+/-3.5%, DLCO=-10.3+/-6.9%, and PDLNO post-exercise such that 68% of the variance in the change in DLCO was accounted for by the variance in the change in DLNO (PDLNO/DLCO ratio was not altered post-exercise (5.87+/-0.37) compared to pre-exercise (5.70+/-0.34). We conclude that the decrease in single-breath DLNO and DLCO from pre- to post-exercise is similar, the magnitude of the change in DLCO closely reflects that of the change in DLNO, and single-breath DLNO/DLCO ratios are independent of the timing of measurement suggesting that using NO and CO transfer gases are valid in looking at short-term changes in lung diffusional conductance.

  8. Photochemical oxidation of water and reduction of polyoxometalate anions at interfaces of water with ionic liquids or diethylether

    Science.gov (United States)

    Bernardini, Gianluca; Wedd, Anthony G.; Zhao, Chuan; Bond, Alan M.

    2012-01-01

    Photoreduction of [P2W18O62]6-, [S2Mo18O62]4-, and [S2W18O62]4- polyoxometalate anions (POMs) and oxidation of water occurs when water–ionic liquid and water–diethylether interfaces are irradiated with white light (275–750 nm) or sunlight. The ionic liquids (ILs) employed were aprotic ([Bmim]X; Bmim = (1-butyl-3-methylimidazolium,X = BF4,PF6) and protic (DEAS = diethanolamine hydrogen sulphate; DEAP = diethanolamine hydrogen phosphate). Photochemical formation of reduced POMs at both thermodynamically stable and unstable water–IL interfaces led to their initial diffusion into the aqueous phase and subsequent extraction into the IL phase. The mass transport was monitored visually by color change and by steady-state voltammetry at microelectrodes placed near the interface and in the bulk solution phases. However, no diffusion into the organic phase was observed when [P2W18O62]6- was photo-reduced at the water–diethylether interface. In all cases, water acted as the electron donor to give the overall process: 4POM + 2H2O + hν → 4POM- + 4H+ + O2. However, more highly reduced POM species are likely to be generated as intermediates. The rate of diffusion of photo-generated POM- was dependent on the initial concentration of oxidized POM and the viscosity of the IL (or mixed phase system produced in cases in which the interface is thermodynamically unstable). In the water-DEAS system, the evolution of dioxygen was monitored in situ in the aqueous phase by using a Clark-type oxygen sensor. Differences in the structures of bulk and interfacial water are implicated in the activation of water. An analogous series of reactions occurred upon irradiation of solid POM salts in the presence of water vapor. PMID:22753501

  9. Oxidative capacity and radical chemistry in the polluted atmosphere of Hong Kong and Pearl River Delta region: analysis of a severe photochemical smog episode

    Science.gov (United States)

    Xue, Likun; Gu, Rongrong; Wang, Tao; Wang, Xinfeng; Saunders, Sandra; Blake, Donald; Louie, Peter K. K.; Luk, Connie W. Y.; Simpson, Isobel; Xu, Zheng; Wang, Zhe; Gao, Yuan; Lee, Shuncheng; Mellouki, Abdelwahid; Wang, Wenxing

    2016-08-01

    We analyze a photochemical smog episode to understand the oxidative capacity and radical chemistry of the polluted atmosphere in Hong Kong and the Pearl River Delta (PRD) region. A photochemical box model based on the Master Chemical Mechanism (MCM v3.2) is constrained by an intensive set of field observations to elucidate the budgets of ROx (ROx = OH+HO2+RO2) and NO3 radicals. Highly abundant radical precursors (i.e. O3, HONO and carbonyls), nitrogen oxides (NOx) and volatile organic compounds (VOCs) facilitate strong production and efficient recycling of ROx radicals. The OH reactivity is dominated by oxygenated VOCs (OVOCs), followed by aromatics, alkenes and alkanes. Photolysis of OVOCs (except for formaldehyde) is the dominant primary source of ROx with average daytime contributions of 34-47 %. HONO photolysis is the largest contributor to OH and the second-most significant source (19-22 %) of ROx. Other considerable ROx sources include O3 photolysis (11-20 %), formaldehyde photolysis (10-16 %), and ozonolysis reactions of unsaturated VOCs (3.9-6.2 %). In one case when solar irradiation was attenuated, possibly by the high aerosol loadings, NO3 became an important oxidant and the NO3-initiated VOC oxidation presented another significant ROx source (6.2 %) even during daytime. This study suggests the possible impacts of daytime NO3 chemistry in the polluted atmospheres under conditions with the co-existence of abundant O3, NO2, VOCs and aerosols, and also provides new insights into the radical chemistry that essentially drives the formation of photochemical smog in the high-NOx environment of Hong Kong and the PRD region.

  10. Preparation of conducting polymer patterns using photochemical reaction of oxidation polymerization agents; Sanka jugozai no hikarikagaku henka wo riyoshita dodensei kobunshi patan no seisaku hoho

    Energy Technology Data Exchange (ETDEWEB)

    Onishi, Yasushi; Naruse, Tsutomu; Yoshimoto, Shoji; Kimura, Kazuyuki [Aichi Prefectura Goverment, Aichi (Japan). Institute of Industrial Research; Natsume, Yukihiro [Aica Kogyo Corp., Aichi (Japan)

    1999-09-10

    Preparation of conducting polymer patterns using the photochemical oxidizing ability changes of an oxidation polymerization agent has been investigated. Photoreactive metal salts such as iron (3) chloride were used for oxidation polymerization of conducting polymers such as polymers such as polypyrrole. Metal salts were reduced by exposing to ultra-violet (UV) light and missed the ability of oxidation polymerization. Therefore, conducting polypyrrole patterns have been prepared on the unirradiated part by exposing films containing iron (3) chloride to UV light through the pattern mask and then contacting with pyrrole vapor or dipping in pyrrole solution. By this method, large and fine conducting polymer patterns can easily be prepared on plastics, ceramics, papers, clothes, woods, etc. In addition, it may be able to prepare patterns with partially different conductivity by controlling the irradiation time of UV light and/or shades of the pattern masks. (author)

  11. Hydrogenase activity in Azospirillum brasilense is inhibited by nitrite, nitric oxide, carbon monoxide, and acetylene

    Energy Technology Data Exchange (ETDEWEB)

    Tibelius, K.H.; Knowles, R.

    1984-10-01

    Nitrite, NO, CO, and C/sub 2/H/sub 2/ inhibited O/sub 2/-dependent H/sub 2/ uptake (H/sup 3/H oxidation) in denitrifying Azospirillum brasilense Sp7 grown anaerobically on N/sub 2/O or NO/sub 3//sup -/. The apparent K/sub i/ values for inhibition of O/sub 2/-dependent H/sub 2/ uptake were 20 ..mu..M for NO/sub 2//sup -/, 0.4 ..mu..M for NO, 28 ..mu..M for CO, and 88 ..mu..M for C/sub 2/H/sub 2/. These inhibitors also affected methylene blue-dependent H/sub 2/ uptake, presumably by acting directly on the hydrogenase. Nitrite and NO inhibited H/sub 2/ uptake irreversibly, whereas inhibition due to CO was easily reversed by repeatedly evacuating and backfilling with N/sub 2/. The C/sub 2/H/sub 2/ inhibition was not readily reversed, partly due to difficulty in removing the last traces of this gas from solution. The NO/sub 2//sup -/ inhibition of malate-dependent respiration was readily reversed by repeatedly washing the cells, in contrast to the effect of NO/sub 2//sup -/ on H/sub 2/-dependent respiration. These results suggest that the low hydrogenase activities observed in NO/sub 3//sup -/-grown cultures of A. brasilense may be due to the irreversible inhibition of hydrogenase by NO/sub 2//sup -/ and NO produced by NO/sub 3//sup -/ reduction.

  12. Mixed N-Heterocyclic Carbene-Bis(oxazolinyl)borato Rhodium and Iridium Complexes in Photochemical and Thermal Oxidative Addition Reactions

    Energy Technology Data Exchange (ETDEWEB)

    Xu, Songchen [Ames Laboratory; Manna, Kuntal [Ames Laboratory; Ellern, Arkady [Ames Laboratory; Sadow, Aaron D [Ames Laboratory

    2014-12-08

    In order to facilitate oxidative addition chemistry of fac-coordinated rhodium(I) and iridium(I) compounds, carbene–bis(oxazolinyl)phenylborate proligands have been synthesized and reacted with organometallic precursors. Two proligands, PhB(OxMe2)2(ImtBuH) (H[1]; OxMe2 = 4,4-dimethyl-2-oxazoline; ImtBuH = 1-tert-butylimidazole) and PhB(OxMe2)2(ImMesH) (H[2]; ImMesH = 1-mesitylimidazole), are deprotonated with potassium benzyl to generate K[1] and K[2], and these potassium compounds serve as reagents for the synthesis of a series of rhodium and iridium complexes. Cyclooctadiene and dicarbonyl compounds {PhB(OxMe2)2ImtBu}Rh(η4-C8H12) (3), {PhB(OxMe2)2ImMes}Rh(η4-C8H12) (4), {PhB(OxMe2)2ImMes}Rh(CO)2 (5), {PhB(OxMe2)2ImMes}Ir(η4-C8H12) (6), and {PhB(OxMe2)2ImMes}Ir(CO)2 (7) are synthesized along with ToMM(η4-C8H12) (M = Rh (8); M = Ir (9); ToM = tris(4,4-dimethyl-2-oxazolinyl)phenylborate). The spectroscopic and structural properties and reactivity of this series of compounds show electronic and steric effects of substituents on the imidazole (tert-butyl vs mesityl), effects of replacing an oxazoline in ToM with a carbene donor, and the influence of the donor ligand (CO vs C8H12). The reactions of K[2] and [M(μ-Cl)(η2-C8H14)2]2 (M = Rh, Ir) provide {κ4-PhB(OxMe2)2ImMes'CH2}Rh(μ-H)(μ-Cl)Rh(η2-C8H14)2 (10) and {PhB(OxMe2)2ImMes}IrH(η3-C8H13) (11). In the former compound, a spontaneous oxidative addition of a mesityl ortho-methyl to give a mixed-valent dirhodium species is observed, while the iridium compound forms a monometallic allyl hydride. Photochemical reactions of dicarbonyl compounds 5 and 7 result in C–H bond oxidative addition providing the compounds {κ4-PhB(OxMe2)2ImMes'CH2}RhH(CO) (12) and {PhB(OxMe2)2ImMes}IrH(Ph)CO (13). In 12, oxidative addition results in cyclometalation of the mesityl ortho-methyl similar to 10, whereas the iridium compound reacts with the benzene solvent to give a rare crystallographically characterized cis

  13. Comparative Assessment of Antimicrobial Efficiency of Ionic Silver, Silver Monoxide, and Metallic Silver Incorporated onto an Aluminum Oxide Nanopowder Carrier

    Directory of Open Access Journals (Sweden)

    Agnieszka Maria Jastrzębska

    2013-01-01

    Full Text Available The present paper provides comparative assessment of antimicrobial efficiency of ionic silver (Ag+, silver monoxide (Ag2O, and metallic silver (Ag incorporated onto an aluminum oxide nanopowder carrier (Al2O3. The deposition of Ag+ ions, Ag2O nanoparticles, and Ag nanoparticles on an different phases of aluminum oxide nanopowder carrier was realized using consecutive stages of dry sol-gel method. The Al2O3-Ag+, Al2O3-Ag2O, and Al2O3-Ag nanopowders were widely characterized qualitatively and quantitatively by SEM, physical nitrogen sorption and XRD analyses. Results indicate that the Al2O3 nanopowders added with Ag+, Ag2O, and Ag, apart from phase composition, were not differing considerably from one another in terms of their morphology and physical properties. However, nanopowders of Al2O3-Ag were more agglomerated than Al2O3-Ag2O and Al2O3-Ag+ nanopowders. The antibacterial activity of the nanopowders was examined by the spread plate method using bacterial strains such as Escherichia coli, Sarcina lutea, and Bacillus subtilis. The best antibacterial properties against Sarcina lutea strain were achieved in the amorphous-Al2O3-Ag+ and Al2O3-Ag2O nanopowders, whereas the worst antimicrobial activity against Bacillus subtilis and Escherichia coli was shown by the Al2O3-Ag+ and Al2O3-Ag nanopowders. The observed increase of the antibacterial activity as the silver content was not however significant for Al2O3-Ag nanopowders. The results obtained in the present experiments show that the Al2O3-Ag+, Al2O3-Ag2O, and Al2O3-Ag nanopowders, possessing good bactericidal properties, can be produced by using consecutive stages of dry sol-gel method, and Al2O3 nanopowder added with Ag2O is considered as the best raw material in the production of antiseptic materials.

  14. Photochemical nitric oxide precursors: synthesis, photochemistry, and ligand substitution kinetics of ruthenium salen nitrosyl and ruthenium salophen nitrosyl complexes.

    Science.gov (United States)

    Works, Carmen F; Jocher, Christoph J; Bart, Gwen D; Bu, Xianhui; Ford, Peter C

    2002-07-15

    Described are syntheses, characterizations, and photochemical reactions of the nitrosyl complexes Ru(salen)(ONO)(NO) (I, salen = N,N'-ethylenebis(salicylideneiminato) dianion), Ru(salen)(Cl)(NO) (II), Ru((t)Bu(4)salen)(Cl)(NO) (III,(t)Bu(4)salen = N,N'-ethylenebis(3,5-di-tert-butylsalicylideneiminato) dianion), Ru((t)Bu(4)salen)(ONO)(NO) (IV), Ru((t)Bu(2)salophen)(Cl)(NO) (V, (t)Bu(2)salophen = N,N'-1,2-phenylenediaminebis(3-tert-butylsalicylideneiminato) dianion), and Ru((t)Bu(4)salophen)(Cl)(NO) (VI, (t)Bu(4)salophen = N,N'-1,2-phenylenebis(3,5-di-tert-butylsalicylideneiminato) dianion). Upon photolysis, these Ru(L)(X)(NO) compounds undergo NO dissociation to give the ruthenium(III) solvento products Ru(L)(X)(Sol). Quantum yields for 365 nm irradiation in acetonitrile solution fall in a fairly narrow range (0.055-0.13) but decreased at longer lambda(irr). The quantum yield (lambda(irr) = 365 nm) for NO release from the water soluble complex [Ru(salen)(H(2)O)(NO)]Cl (VII) was 0.005 in water. Kinetics of thermal back-reactions to re-form the nitrosyl complexes demonstrated strong solvent dependence with second-order rate constants k(NO) varying from 5 x 10(-4) M(-1) s(-1) for the re-formation of II in acetonitrile to 5 x 10(8) M(-1) s(-1) for re-formation of III in cyclohexane. Pressure and temperature effects on the back-reaction rates were also examined. These results are relevant to possible applications of photochemistry for nitric oxide delivery to biological targets, to the mechanisms by which NO reacts with metal centers to form metal-nitrosyl bonds, and to the role of photochemistry in activating similar compounds as catalysts for several organic transformations. Also described are the X-ray crystal structures of I and V.

  15. Catalytic Oxidation of Propylene, Toluene, Carbon Monoxide, and Carbon Black over Au/CeO2 Solids: Comparing the Impregnation and the Deposition-Precipitation Methods

    Directory of Open Access Journals (Sweden)

    Antoine Aboukaïs

    2013-01-01

    Full Text Available Au/CeO2 solids were prepared by two methods: deposition-precipitation (DP and impregnation (Imp. The prepared solids were calcined under air at 400°C. Both types of catalysts have been tested in the total oxidation of propylene, toluene, carbon monoxide, and carbon black. Au/CeO2-DP solids were the most reactive owing to the high number of gold nanoparticles and Au+ species and the low concentration of Cl- ions present on its surface compared to those observed in Au/CeO2-Imp solids.

  16. Tropospheric Ozone and Photochemical Smog

    Science.gov (United States)

    Sillman, S.

    2003-12-01

    The question of air quality in polluted regions represents one of the issues of geochemistry with direct implications for human well-being. Human health and well-being, along with the well-being of plants, animals, and agricultural crops, are dependent on the quality of air we breathe. Since the start of the industrial era, air quality has become a matter of major importance, especially in large cities or urbanized regions with heavy automobile traffic and industrial activity.Concern over air quality existed as far back as the 1600s. Originally, polluted air in cities resulted from the burning of wood or coal, largely as a source of heat. The industrial revolution in England saw a great increase in the use of coal in rapidly growing cities, both for industrial use and domestic heating. London suffered from devastating pollution events during the late 1800s and early 1900s, with thousands of excess deaths attributed to air pollution (Brimblecombe, 1987). With increasing use of coal, other instances also occurred in continental Europe and the USA. These events were caused by directly emitted pollutants (primary pollutants), including sulfur dioxide (SO2), carbon monoxide (CO), and particulates. They were especially acute in cities with northerly locations during fall and winter when sunlight is at a minimum. These original pollution events gave rise to the term "smog" (a combination of smoke and fog). Events of this type have become much less severe since the 1950s in Western Europe and the US, as natural gas replaced coal as the primary source of home heating, industrial smokestacks were designed to emit at higher altitudes (where dispersion is more rapid), and industries were required to install pollution control equipment.Beginning in the 1950s, a new type of pollution, photochemical smog, became a major concern. Photochemical smog consists of ozone (O3) and other closely related species ("secondary pollutants") that are produced photochemically from directly

  17. Kinetic and mechanistic studies of reactive intermediates in photochemical and transition metal-assisted oxidation, decarboxylation and alkyl transfer reactions

    Science.gov (United States)

    Carraher, Jack McCaslin

    -olefins selectively. This process is made catalytic by the introduction of O2. Photochemical decarboxylation of propionic acid in the presence of Cu2+ generates ethylene and Cu +. Longer-chain acids also yield alpha olefins as exclusive products. In the absence of continued purging with O2 to aid removal of olefin, Cu+(olefin) complexes accumulate and catalytic activity slows dramatically due to depletion of Cu2+. The results underscore the profound effect that the choice of metal ions, the medium, and reaction conditions exert on the photochemistry of carboxylic acids. Free Oxygen Atom in Solution from 4-Benzoylpyridine N-Oxide Excited Singlet. Photolysis of 4-benzoylpyridine N-oxide (BPyO) in the presence of quenchers of the triplet excited state produces up to 41% O(3P) (as determined by generation of ethylene upon scavenging with cyclopentene). In the absence of 3BPyO* quenchers a maximum of 13% O(3P) relative to consumed BPyO is obtained. The remaining products are hydroxylated-4-benzoylpyridine and 4-benzoylpyridine. Additionally, the rate of BPyO consumption (as determined by UV-vis) decreases in the presence of 3BPyO* quenching agents. Second order rate constants for 3BPyO* quenching were determined. A mechanism for photochemical deoxygenation of BPyO is proposed on the basis of kinetic data and product distribution under various conditions. Additionally, comparisons are made between the observed intermediates and similar triplet excited states and radical anions.

  18. Gas-phase energies of actinide oxides -- an assessment of neutral and cationic monoxides and dioxides from thorium to curium

    Energy Technology Data Exchange (ETDEWEB)

    Marcalo, Joaquim; Gibson, John K.

    2009-08-10

    An assessment of the gas-phase energetics of neutral and singly and doubly charged cationic actinide monoxides and dioxides of thorium, protactinium, uranium, neptunium, plutonium, americium, and curium is presented. A consistent set of metal-oxygen bond dissociation enthalpies, ionization energies, and enthalpies of formation, including new or revised values, is proposed, mainly based on recent experimental data and on correlations with the electronic energetics of the atoms or cations and with condensed-phase thermochemistry.

  19. Near-ambient X-ray photoemission spectroscopy and kinetic approach to the mechanism of carbon monoxide oxidation over lanthanum substituted cobaltites

    Energy Technology Data Exchange (ETDEWEB)

    Hueso, J. L.; Martinez-Martinez, D.; Cabalerro, Alfonso; Gonzalez-Elipe, Agustin Rodriguez; Mun, Bongjin Simon; Salmeron, Miquel

    2009-07-31

    We have studied the oxidation of carbon monoxide over a lanthanum substituted perovskite (La0.5Sr0.5CoO3-d) catalyst prepared by spray pyrolysis. Under the assumption of a first-order kinetics mechanism for CO, it has been found that the activation energy barrier of the reaction changes from 80 to 40 kJ mol-1 at a threshold temperature of ca. 320 oC. In situ XPS near-ambient pressure ( 0.2 torr) shows that the gas phase oxygen concentration over the sample decreases sharply at ca. 300 oC. These two observations suggest that the oxidation of CO undergoes a change of mechanism at temperatures higher than 300 oC.

  20. Real-Time Studies of Iron Oxalate-Mediated Oxidation of Glycolaldehyde as a Model for Photochemical Aging of Aqueous Tropospheric Aerosols.

    Science.gov (United States)

    Thomas, Daniel A; Coggon, Matthew M; Lignell, Hanna; Schilling, Katherine A; Zhang, Xuan; Schwantes, Rebecca H; Flagan, Richard C; Seinfeld, John H; Beauchamp, J L

    2016-11-15

    The complexation of iron(III) with oxalic acid in aqueous solution yields a strongly absorbing chromophore that undergoes efficient photodissociation to give iron(II) and the carbon dioxide anion radical. Importantly, iron(III) oxalate complexes absorb near-UV radiation (λ > 350 nm), providing a potentially powerful source of oxidants in aqueous tropospheric chemistry. Although this photochemical system has been studied extensively, the mechanistic details associated with its role in the oxidation of dissolved organic matter within aqueous aerosol remain largely unknown. This study utilizes glycolaldehyde as a model organic species to examine the oxidation pathways and evolution of organic aerosol initiated by the photodissociation of aqueous iron(III) oxalate complexes. Hanging droplets (radius 1 mm) containing iron(III), oxalic acid, glycolaldehyde, and ammonium sulfate (pH ∼3) are exposed to irradiation at 365 nm and sampled at discrete time points utilizing field-induced droplet ionization mass spectrometry (FIDI-MS). Glycolaldehyde is found to undergo rapid oxidation to form glyoxal, glycolic acid, and glyoxylic acid, but the formation of high molecular weight oligomers is not observed. For comparison, particle-phase experiments conducted in a laboratory chamber explore the reactive uptake of gas-phase glycolaldehyde onto aqueous seed aerosol containing iron and oxalic acid. The presence of iron oxalate in seed aerosol is found to inhibit aerosol growth. These results suggest that photodissociation of iron(III) oxalate can lead to the formation of volatile oxidation products in tropospheric aqueous aerosols.

  1. Final Technical Report "Catalytic Hydrogenation of Carbon Monoxide and Olefin Oxidation" Grant number : DE-FG02-86ER13615

    Energy Technology Data Exchange (ETDEWEB)

    Wayland, B.B.

    2009-08-31

    Title: Catalytic Hydrogenation of Carbon Monoxide and Olefin Oxidation Grant No. DE-FG02-86ER13615 PI: Wayland, B. B. (wayland@sas.upenn.edu) Abstract Development of new mechanistic strategies and catalyst materials for activation of CO, H2, CH4, C2H4, O2, and related substrates relevant to the conversion of carbon monoxide, alkanes, and alkenes to organic oxygenates are central objectives encompassed by this program. Design and synthesis of metal complexes that manifest reactivity patterns associated with potential pathways for the hydrogenation of carbon monoxide through metallo-formyl (M-CHO), dimetal ketone (M-C(O)-M), and dimetal dionyl (M-C(O)-C(O)-M) species is one major focus. Hydrocarbon oxidation using molecular oxygen is a central goal for methane activation and functionalization as well as regioselective oxidation of olefins. Discovery of new reactivity patterns and control of selectivity are pursued through designing new metal complexes and adjusting reaction conditions. Variation of reaction media promotes distinct reaction pathways that control both reaction rates and selectivities. Dimetalloradical diporphyrin complexes preorganize transition states for substrate reactions that involve two metal centers and manifest large rate increases over mono-metalloradical reactions of hydrogen, methane, and other small molecule substrates. Another broad goal and recurring theme of this program is to contribute to the thermodynamic database for a wide scope of organo-metal transformations in a range of reaction media. One of the most complete descriptions of equilibrium thermodynamics for organometallic reactions in water and methanol is emerging from the study of rhodium porphyrin substrate reactions in aqueous and alcoholic media. Water soluble group nine metalloporphyrins manifest remarkably versatile substrate reactivity in aqueous and alcoholic media which includes producing rhodium formyl (Rh-CHO) and hydroxy methyl (Rh-CH2OH) species. Exploratory

  2. Effect of the chemical termination of conductive diamond substrate on the resistance to carbon monoxide-poisoning during methanol oxidation of platinum particles

    Science.gov (United States)

    Spătaru, Tanţa; Osiceanu, Petre; Anastasescu, Mihai; Pătrinoiu, Greta; Munteanu, Cornel; Spătaru, Nicolae; Fujishima, Akira

    2014-09-01

    Boron-doped diamond (BDD) films were annealed in hydrogen or oxygen streams and were further used as substrates for Pt electrochemical deposition. SEM and AFM measurements have shown that, from the point of view of the efficiency of noble metal utilization, a hydrogen-terminated diamond (HT-BDD) support is more convenient because it enables better dispersion and smaller size of the deposited particles. An enhancement of ca. 23% of the electrocatalyst specific surface area was observed for Pt/HT-BDD, compared to the case of Pt deposited at oxygen-terminated diamond (OT-BDD). Nevertheless, it was found that when deposited on oxidized BDD, Pt particles are more resistant to fouling during methanol oxidation. Electrochemical oxidation of adsorbed carbon monoxide was investigated by anodic stripping voltammetry and it was demonstrated that the use of OT-BDD substrate facilitates oxidative desorption of CO from the platinum active sites. This behavior was tentatively ascribed to the high surface concentration of oxygenated carbon species, evidenced by XPS, which may act as oxygen donors and/or could partially weaken Pt-CO bonds, thus enabling easier CO eviction from the electrocatalyst surface.

  3. Distribution and diversity of carbon monoxide-oxidizing bacteria and bulk bacterial communities across a succession gradient on a Hawaiian volcanic deposit.

    Science.gov (United States)

    Weber, C F; King, G M

    2010-07-01

    Relatively little is known about the distribution and diversity of CO-oxidizing bacteria during succession on volcanic deposits even though they are among the primary colonists. We surveyed CO-oxidizing communities across a vegetation gradient on a 1959 cinder deposit using coxL (large subunit gene of carbon monoxide dehydrogenase) sequences. Sequences most closely related to a coxL sequence from Ktedonobacter racemifer, dominated unvegetated cinders, while Proteobacteria-like sequences dominated vegetated sites. The number of coxL operational taxonomic units (OTUs) increased threefold with increased vegetation, and correlated most strongly with the increased beta-Proteobacteria richness (r = 0.987). These compositional shifts were also reflected in overall bacterial community compositions as determined by 16S rRNA gene analysis. Notably, coxL OTU:16S rRNA OTU ratios increased with increased vegetation, indicating that CO oxidizers became a larger fraction of total bacterial richness during succession. Results from most probable number estimates and maximum potential CO uptake activity assays indicate that increased richness is paralleled by increased CO oxidizer abundance, which likely results from increased vegetation and organic carbon content. Collectively, results suggest that in contrast to patterns observed for plant succession, a versatile bacterial functional group that is important during early colonization and succession can remain important in later stages of succession, irrespective of dramatic environmental changes.

  4. Electrochemical oxidation of carbon monoxide: from platinum single crystals to low temperature fuel catalysts. Part II: Electrooxidation of H2, CO and H2/CO mixtures on well characterized PtMo alloy

    Directory of Open Access Journals (Sweden)

    PHILIP N. ROSS JR.

    2003-03-01

    Full Text Available The oxidation of hydrogen and hydrogen–carbon monoxide mixture has been investigated on well-characterized metallurgically prepared platinum–molybdenum (PtMo alloys. It was concluded that the optimum surface concentration of molybdenum is near 23 mol.%. Based on experimentally determined parameters and simulations, the mechanism of the oxidation of CO/H2 mixtures is discussed.

  5. Spectroelectrochemical Study of Carbon Monoxide and Ethanol Oxidation on Pt/C, PtSn(3:1/C and PtSn(1:1/C Catalysts

    Directory of Open Access Journals (Sweden)

    Rubén Rizo

    2016-09-01

    Full Text Available PtSn-based catalysts are one of the most active materials toward that contribute ethanol oxidation reaction (EOR. In order to gain a better understanding of the Sn influence on the carbon monoxide (principal catalyst poison and ethanol oxidation reactions in acidic media, a systematic spectroelectrochemical study was carried out. With this end, carbon-supported PtSnx (x = 0, 1/3 and 1 materials were synthesized and employed as anodic catalysts for both reactions. In situ Fourier transform infrared spectroscopy (FTIRS and differential electrochemical mass spectrometry (DEMS indicate that Sn diminishes the amount of bridge bonded CO (COB and greatly improves the CO tolerance of Pt-based catalysts. Regarding the effect of Sn loading on the EOR, it enhances the catalytic activity and decreases the onset potential. FTIRS and DEMS analysis indicate that the C-C bond scission occurs at low overpotentials and at the same potential values regardless of the Sn loading, although the amount of C-C bond breaking decreases with the rise of Sn in the catalytic material. Therefore, the elevated catalytic activity toward the EOR at PtSn-based electrodes is mainly associated with the improved CO tolerance and the incomplete oxidation of ethanol to form acetic acid and acetaldehyde species, causing the formation of a higher amount of both C2 products with the rise of Sn loading.

  6. Catalysis of Photochemical Reactions.

    Science.gov (United States)

    Albini, A.

    1986-01-01

    Offers a classification system of catalytic effects in photochemical reactions, contrasting characteristic properties of photochemical and thermal reactions. Discusses catalysis and sensitization, examples of catalyzed reactions of excepted states, complexing ground state substrates, and catalysis of primary photoproducts. (JM)

  7. Carbon monoxide poisoning

    Science.gov (United States)

    ... and smokers. Carbon monoxide can harm a fetus (unborn baby still in the womb). Symptoms of carbon ... symptoms Outlook (Prognosis) Carbon monoxide poisoning can cause death. For those who survive, recovery is slow. How ...

  8. Low-temperature carbon monoxide oxidation over zirconia-supported CuO-CeO2 catalysts: Effect of zirconia support properties

    Science.gov (United States)

    Moretti, Elisa; Molina, Antonia Infantes; Sponchia, Gabriele; Talon, Aldo; Frattini, Romana; Rodriguez-Castellon, Enrique; Storaro, Loretta

    2017-05-01

    A study was conducted to investigate the effect of the preparation route of ZrO2 in CuO-CeO2/ZrO2 catalysts for the oxidation of carbon monoxide at low temperature (COX). Four ZrO2 supports were synthetized via either type sol-gel methodology or precipitation. The final Cu-Ce-Zr oxide catalysts were prepared by incipient wetness co-impregnation with copper and cerium solutions (with a loading of 6 wt% of CuO and 20 wt% of CeO2). The catalyst crystalline phases, texture and active species reducibility were determined by XRD, N2 physisorption at -196 °C and H2-TPR, respectively; meanwhile the surface composition and copper-cerium electronic states were studied by XPS. The catalytic activity was evaluated in the oxidation of CO to CO2, in the 40-215 °C temperature range. Catalytic results evidenced that the samples prepared by a sol-gel methodology showed, after the impregnation, a severe decrease of specific surface area and pore volume attributable to a wide degree of pore blockage caused by the presence of metal oxide particles and a collapse of the structure partially burying the active sites. A simple co-impregnation of a zirconia support, obtained through facile and fast precipitation, provided instead a catalyst with very good redox properties and high dispersion of the active phases, which completely oxidizes CO in the range 115-215 °C with T50 of 65 °C. This higher observed activity was ascribed to the formation of a larger fraction of highly dispersed and easily reducible Cu species and ceria nanocrystallites, mainly present as Ce(IV), with an average size of 5 nm.

  9. CARBON MONOXIDE TREATMENT GUIDELINES

    Directory of Open Access Journals (Sweden)

    Miran Brvar

    2014-02-01

    Full Text Available Carbon monoxide is the leading cause of unintentional poisoning-related death in Slovenia. It is an odorless, colorless gas that usually remains undetectable until exposures result in injury or death. Exposure to carbon monoxide is most commonly accompanied by headache, nausea, vomiting, dizziness, confusion, drowsiness, fatigue and collapse. Carbon monoxide poisoning management includes normobaric oxygen therapy. Hyperbaric-oxygen treatments reduce the risk of cognitive sequelae after carbon monoxide poisoning. 

  10. Oxidant and particle photochemical processes above a south-east Asian tropical rain forest (the OP3 project: introduction, rationale, location characteristics and tools

    Directory of Open Access Journals (Sweden)

    C. N. Hewitt

    2009-09-01

    Full Text Available In April–July 2008, intensive measurements were made of atmospheric composition and chemistry in Sabah, Malaysia, as part of the "Oxidant and particle photochemical processes above a South-East Asian tropical rain forest" (OP3 project. Fluxes and concentrations of trace gases and particles were made from and above the rain forest canopy at the Bukit Atur Global Atmosphere Watch station and at the nearby Sabahmas oil palm plantation, using both ground-based and airborne measurements. Here, the measurement and modelling strategies used, the characteristics of the sites and an overview of data obtained are described. Composition measurements show that the rainforest site was not impacted by significant sources of anthropogenic pollution, and this is confirmed by satellite retrievals of NO2 and HCHO. The dominant modulators of atmospheric chemistry at the rain forest site were therefore emissions of BVOCs and soil emissions of reactive nitrogen oxides. At the observed BVOC:NOx volume mixing ratio (~104 pptv/pptv, current chemical models suggest that daytime maximum OH concentrations should be ca. 105 radicals cm−3, but observed OH concentrations were an order of magnitude greater than this. We confirm, therefore, previous measurements which suggest that an unexplained source of OH must exist above tropical forests and continue to interrogate the data to find explanations for this.

  11. Overview: oxidant and particle photochemical processes above a south-east Asian tropical rainforest (the OP3 project: introduction, rationale, location characteristics and tools

    Directory of Open Access Journals (Sweden)

    C. N. Hewitt

    2010-01-01

    Full Text Available In April–July 2008, intensive measurements were made of atmospheric composition and chemistry in Sabah, Malaysia, as part of the "Oxidant and particle photochemical processes above a South-East Asian tropical rainforest" (OP3 project. Fluxes and concentrations of trace gases and particles were made from and above the rainforest canopy at the Bukit Atur Global Atmosphere Watch station and at the nearby Sabahmas oil palm plantation, using both ground-based and airborne measurements. Here, the measurement and modelling strategies used, the characteristics of the sites and an overview of data obtained are described. Composition measurements show that the rainforest site was not significantly impacted by anthropogenic pollution, and this is confirmed by satellite retrievals of NO2 and HCHO. The dominant modulators of atmospheric chemistry at the rainforest site were therefore emissions of BVOCs and soil emissions of reactive nitrogen oxides. At the observed BVOC:NOx volume mixing ratio (~100 pptv/pptv, current chemical models suggest that daytime maximum OH concentrations should be ca. 105 radicals cm−3, but observed OH concentrations were an order of magnitude greater than this. We confirm, therefore, previous measurements that suggest that an unexplained source of OH must exist above tropical rainforest and we continue to interrogate the data to find explanations for this.

  12. Fe{sup 3+}-doped zeolites. Optimised conditions for the oxidative degradation of 2,4-xylidine in laboratory and solar photochemical reactors

    Energy Technology Data Exchange (ETDEWEB)

    Shahin, N.; Thanh, H. le; Bonfill, A.; Woerner, M.; Lang, J.; Bossmann, S.H.; Oliveros, E.; Braun, A.M. [Lehrstuhl fuer Umweltmesstechnik am Engler-Bunte Inst. der Univ. Karlsruhe (Germany)

    2003-07-01

    Among advanced oxidation processes (AOP), the photochemically enhanced Fenton reaction (photo-Fenton) may be considered as one of the most efficient for the degradation of contaminants in industrial wastewater. This process involves a series of complex reactions, which cannot be described completely by conventional models. Therefore, the experimental design methodology has been employed for modelling the experimental data obtained in a laboratory batch reactor as well as in a novel type of solar reactor. As heterogeneous Fenton catalyst, a Fe{sup 3+}-exchanged zeolite Y photocatalyst was employed. As a model pollutant, 2,4-dimethyl aniline (2,4-xylidine) was chosen, because its oxidative degradation chemistry is well known. The experimental design model has been used for describing the behaviour of the reaction system in sensitivity studies aimed at optimising the amounts of Fenton reagents (heterogeneous Fenton catalyst and hydrogen peroxide) employed in the process. The results show that this heterogeneous photo-Fenton process is very sensitive to the concentration of catalyst as well as of added hydrogen peroxide. (orig.)

  13. Photochemical Oxidation of a Manganese(III) Complex with Oxygen and Toluene Derivatives to Form a Manganese(V)-Oxo Complex

    Science.gov (United States)

    Jung, Jieun; Ohkubo, Kei; Prokop-Prigge, Katharine A.; Neu, Heather M.; Goldberg, David P.; Fukuzumi, Shunichi

    2013-01-01

    Visible light photoirradiation of an oxygen-saturated benzonitrile solution of a manganese(III) corrolazine complex [(TBP8Cz)MnIII (1): [TBP8Cz = octakis(p-tert-butylphenyl)corrolazinato3−] in the presence of toluene derivatives resulted in formation of the manganese(V)-oxo complex [(TBP8Cz)MnV(O)]. The photochemical oxidation of (TBP8Cz)MnIII with O2 and hexamethylbenzene (HMB) led to the isosbestic conversion of 1 to (TBP8Cz)MnV(O), accompanied by the selective oxidation of HMB to pentamethylbenzyl alcohol (87%). The formation rate of (TBP8Cz)MnV(O) increased with methyl group substitution, from toluene, p-xylene, mesitylene, durene, pentamethylbenzene, up to hexamethylbenzene. Deuterium kinetic isotope effects (KIEs) were observed for toluene (KIE = 5.4) and mesitylene (KIE = 5.3). Femtosecond laser flash photolysis of (TBP8Cz)MnIII revealed the formation of a tripquintet excited state, which was rapidly converted to a tripseptet excited state. The tripseptet excited state was shown to be the key, activated state that reacts with O2 via a diffusion-limited rate constant. The data allow for a mechanism to be proposed in which the tripseptet excited state reacts with O2 to give the putative (TBP8Cz)MnIV(O2•−), which then abstracts a hydrogen atom from the toluene derivatives in the rate-determining step. The mechanism of hydrogen abstraction is discussed by comparison of the reactivity with the hydrogen abstraction from the same toluene derivatives by cumylperoxyl radical. Taken together, the data suggest a new catalytic method is accessible for the selective oxidation of C-H bonds with O2 and light, and the first evidence for catalytic oxidation of C–H bonds was obtained with 10-methyl-9,10-dihydroacridine as a substrate. PMID:24219426

  14. Carbon Monoxide Information Center

    Medline Plus

    Full Text Available ... main content Languages 简体中文 English Bahasa Indonesia 한국어 Español ภาษาไทย Tiếng Việt Text Size: Decrease Font Increase ... Monoxide Information Center Carbon Monoxide Information Center En Español The Invisible Killer Carbon monoxide, also known as ...

  15. The Statistical Evolution of Multiple Generations of Oxidation Products in the Photochemical Aging of Chemically Reduced Organic Aerosol

    Energy Technology Data Exchange (ETDEWEB)

    Wilson, Kevin R.; Smith, Jared D.; Kessler, Sean; Kroll, Jesse H.

    2011-10-03

    The heterogeneous reaction of hydroxyl radicals (OH) with squalane and bis(2-ethylhexyl) sebacate (BES) particles are used as model systems to examine how distributions of reactionproducts evolve during the oxidation of chemically reduced organic aerosol. A kinetic model of multigenerational chemistry, which is compared to previously measured (squalane) and new(BES) experimental data, reveals that it is the statistical mixtures of different generations of oxidation products that control the average particle mass and elemental composition during thereaction. The model suggests that more highly oxidized reaction products, although initially formed with low probability, play a large role in the production of gas phase reaction products.In general, these results highlight the importance of considering atmospheric oxidation as a statistical process, further suggesting that the underlying distribution of molecules could playimportant roles in aerosol formation as well as in the evolution of key physicochemical properties such as volatility and hygroscopicity.

  16. Photochemical tyrosine oxidation in the structurally well-defined α3Y protein: proton-coupled electron transfer and a long-lived tyrosine radical.

    Science.gov (United States)

    Glover, Starla D; Jorge, Christine; Liang, Li; Valentine, Kathleen G; Hammarström, Leif; Tommos, Cecilia

    2014-10-08

    Tyrosine oxidation-reduction involves proton-coupled electron transfer (PCET) and a reactive radical state. These properties are effectively controlled in enzymes that use tyrosine as a high-potential, one-electron redox cofactor. The α3Y model protein contains Y32, which can be reversibly oxidized and reduced in voltammetry measurements. Structural and kinetic properties of α3Y are presented. A solution NMR structural analysis reveals that Y32 is the most deeply buried residue in α3Y. Time-resolved spectroscopy using a soluble flash-quench generated [Ru(2,2'-bipyridine)3](3+) oxidant provides high-quality Y32-O• absorption spectra. The rate constant of Y32 oxidation (kPCET) is pH dependent: 1.4 × 10(4) M(-1) s(-1) (pH 5.5), 1.8 × 10(5) M(-1) s(-1) (pH 8.5), 5.4 × 10(3) M(-1) s(-1) (pD 5.5), and 4.0 × 10(4) M(-1) s(-1) (pD 8.5). k(H)/k(D) of Y32 oxidation is 2.5 ± 0.5 and 4.5 ± 0.9 at pH(D) 5.5 and 8.5, respectively. These pH and isotope characteristics suggest a concerted or stepwise, proton-first Y32 oxidation mechanism. The photochemical yield of Y32-O• is 28-58% versus the concentration of [Ru(2,2'-bipyridine)3](3+). Y32-O• decays slowly, t1/2 in the range of 2-10 s, at both pH 5.5 and 8.5, via radical-radical dimerization as shown by second-order kinetics and fluorescence data. The high stability of Y32-O• is discussed relative to the structural properties of the Y32 site. Finally, the static α3Y NMR structure cannot explain (i) how the phenolic proton released upon oxidation is removed or (ii) how two Y32-O• come together to form dityrosine. These observations suggest that the dynamic properties of the protein ensemble may play an essential role in controlling the PCET and radical decay characteristics of α3Y.

  17. Laboratory investigation of photochemical oxidation of organic aerosol from wood fires – Part 1: Measurement and simulation of organic aerosol evolution

    Directory of Open Access Journals (Sweden)

    A. P. Grieshop

    2008-08-01

    Full Text Available Experiments were conducted to investigate the effects of photo-oxidation on organic aerosol (OA in wood smoke by exposing diluted emissions from soft- and hard-wood fires to UV light in a smog chamber. Particle- and gas-phase concentrations were monitored with a suite of instruments including a Proton Transfer Reaction Mass Spectrometer (PTR-MS, an Aerosol Mass Spectrometer (AMS and a thermodenuder to measure aerosol volatility. The measurements highlight how in-plume processing can lead to considerable evolution of the mass and volatility of biomass burning OA. Photochemical oxidation produced substantial new OA, increasing concentrations by a factor of 1.5 to 2.8 after several hours of exposure to typical summertime hydroxyl radical (OH concentrations. Less than 20% of this new OA could be explained using the measured decay of traditional secondary organic aerosol (SOA precursors and a state-of-the-art SOA model. Aging also created less volatile OA; at 50°C between 50 and 80% of the fresh primary OA evaporated but only 20 to 40% of aged OA. Therefore, the data provide additional evidence that primary OA is semivolatile. They also raise questions about the current approach used to simulate OA in chemical transport models, which assume that primary OA are non-volatile but that SOA is semivolatile. Predictions of a volatility basis-set model that explicitly tracks the partitioning and aging of low-volatile organics are compared to the chamber data. This model demonstrates that the OA production observed in these experiments can be explained by oxidation of low volatility organic vapors. The basis-set model can also simulate observed changes in OA volatility and composition, predicting the OA production and the increased oxygenation and decreased volatility of the OA.

  18. Photochemically deposited nano-Ag/sol-gel TiO2-In2O3 mixed oxide mesoporous-assembled nanocrystals for photocatalytic dye degradation.

    Science.gov (United States)

    Sreethawong, Thammanoon; Ngamsinlapasathian, Supachai; Yoshikawa, Susumu

    2014-05-01

    This work focused on the improvement of the photocatalytic activity for Congo Red (CR) azo dye degradation of mesoporous-assembled 0.95 TiO2-0.05 In2O3 mixed oxide photocatalyst (with a TiO2-to-In2O3 molar ratio of 0.95:0.05) by loading with Ag nanoparticles. The mesoporous-assembled 0.95TiO2-0.05In2O3 mixed oxide photocatalyst was synthesized by a hydrolytic sol-gel method with the aid of a structure-directing surfactant, prior to loading with various Ag contents (0.5-2 wt.%) by a photochemical deposition method. The optimum Ag loading content was found to be 1.5 wt.%, exhibiting a great increase in photocatalytic CR dye degradation activity. The 1.5 wt.% Ag-loaded 0.95TiO2-0.05In2O3 mixed oxide photocatalyst was further applied for the CR dye degradation in the presence of water hardness. Different types (Ca2+ and Ca2+ -Mg2+ mixture) and concentrations (200 and 500 mg/l) of water hardness were investigated. The results showed that the water hardness reduced the photocatalytic CR dye degradation activity, particularly for the extremely hard water with 500 mg/l of Ca2+ -Mg2+ mixture. The adjustment of initial solution pH of the CR dye-containing hard water to an appropriate value was found to improve the photocatalytic CR dye degradation activity under the identical reaction conditions.

  19. Integrated electricity and carbon monoxide production

    Energy Technology Data Exchange (ETDEWEB)

    Griffiths, J.

    1994-03-23

    In a process for the production of carbon monoxide and electric power in an IGCC with the removal of sulphur compounds, between the outlet of quenched gas from a partial oxidation unit and a fuel inlet to a combined cycle gas turbine there is a permeable membrane unit to separate a non-permeable stream, which is utilised as a source of carbon monoxide, and a permeate stream, which is used as fuel for the gas turbine of the combined cycle unit. (author)

  20. Photochemical activation of ruthenium(II)-pyridylamine complexes having a pyridine-N-oxide pendant toward oxygenation of organic substrates.

    Science.gov (United States)

    Kojima, Takahiko; Nakayama, Kazuya; Sakaguchi, Miyuki; Ogura, Takashi; Ohkubo, Kei; Fukuzumi, Shunichi

    2011-11-09

    Ruthenium(II)-acetonitrile complexes having η(3)-tris(2-pyridylmethyl)amine (TPA) with an uncoordinated pyridine ring and diimine such as 2,2'-bipyridine (bpy) and 2,2'-bipyrimidine (bpm), [Ru(II)(η(3)-TPA)(diimine)(CH(3)CN)](2+), reacted with m-chloroperbenzoic acid to afford corresponding Ru(II)-acetonitrile complexes having an uncoordinated pyridine-N-oxide arm, [Ru(II)(η(3)-TPA-O)(diimine)(CH(3)CN)](2+), with retention of the coordination environment. Photoirradiation of the acetonitrile complexes having diimine and the η(3)-TPA with the uncoordinated pyridine-N-oxide arm afforded a mixture of [Ru(II)(TPA)(diimine)](2+), intermediate-spin (S = 1) Ru(IV)-oxo complex with uncoordinated pyridine arm, and intermediate-spin Ru(IV)-oxo complex with uncoordinated pyridine-N-oxide arm. A Ru(II) complex bearing an oxygen-bound pyridine-N-oxide as a ligand and bpm as a diimine ligand was also obtained, and its crystal structure was determined by X-ray crystallography. Femtosecond laser flash photolysis of the isolated O-coordinated Ru(II)-pyridine-N-oxide complex has been investigated to reveal the photodynamics. The Ru(IV)-oxo complex with an uncoordinated pyridine moiety was alternatively prepared by reaction of the corresponding acetonitrile complex with 2,6-dichloropyridine-N-oxide (Cl(2)py-O) to identify the Ru(IV)-oxo species. The formation of Ru(IV)-oxo complexes was concluded to proceed via intermolecular oxygen atom transfer from the uncoordinated pyridine-N-oxide to a Ru(II) center on the basis of the results of the reaction with Cl(2)py-O and the concentration dependence of the consumption of the starting Ru(II) complexes having the uncoordinated pyridine-N-oxide moiety. Oxygenation reactions of organic substrates by [Ru(II)(η(3)-TPA-O)(diimine)(CH(3)CN)](2+) were examined under irradiation (at 420 ± 5 nm) and showed selective allylic oxygenation of cyclohexene to give cyclohexen-1-ol and cyclohexen-1-one and cumene oxygenation to afford cumyl alcohol

  1. Separation of emitted and photochemical formaldehyde in Mexico City using a statistical analysis and a new pair of gas-phase tracers

    Science.gov (United States)

    Garcia, A. R.; Volkamer, R.; Molina, L. T.; Molina, M. J.; Samuelson, J.; Mellqvist, J.; Galle, B.; Herndon, S. C.; Kolb, C. E.

    2006-10-01

    Photochemical pollution control strategies require an understanding of photochemical oxidation precursors, making it important to distinguish between primary and secondary sources of HCHO. Estimates for the relative strengths of primary and secondary sources of formaldehyde (HCHO) were obtained using a statistical regression analysis with time series data of carbon monoxide (CO) and glyoxal (CHOCHO) measured in the Mexico City Metropolitan Area (MCMA) during the spring of 2003. Differences between Easter week and more typical weeks are evaluated. The use of CO-CHOCHO as HCHO tracers is more suitable for differentiating primary and secondary sources than CO-O3. The application of the CO-O3 tracer pair to mobile laboratory data suggests a potential in-city source of background HCHO. A significant amount of HCHO observed in the MCMA is associated with primary emissions.

  2. Separation of emitted and photochemical formaldehyde in Mexico City using a statistical analysis and a new pair of gas-phase tracers

    Directory of Open Access Journals (Sweden)

    A. R. Garcia

    2006-01-01

    Full Text Available Photochemical pollution control strategies require an understanding of photochemical oxidation precursors, making it important to distinguish between primary and secondary sources of HCHO. Estimates for the relative strengths of primary and secondary sources of formaldehyde (HCHO were obtained using a statistical regression analysis with time series data of carbon monoxide (CO and glyoxal (CHOCHO measured in the Mexico City Metropolitan Area (MCMA during the spring of 2003. Differences between Easter week and more typical weeks are evaluated. The use of CO-CHOCHO as HCHO tracers is more suitable for differentiating primary and secondary sources than CO-O3. The application of the CO-O3 tracer pair to mobile laboratory data suggests a potential in-city source of background HCHO. A significant amount of HCHO observed in the MCMA is associated with primary emissions.

  3. Separation of emitted and photochemical formaldehyde in Mexico City using a statistical analysis and a new pair of gas-phase tracers

    Directory of Open Access Journals (Sweden)

    A. R. García

    2005-11-01

    Full Text Available Photochemical pollution control strategies require an understanding of photochemical oxidation precursors, making it important to distinguish between primary and secondary sources of HCHO. Estimates for the relative strengths of primary and secondary sources of formaldehyde (HCHO were obtained using a statistical regression analysis with time series data of carbon monoxide (CO and glyoxal (CHOCHO measured in the Mexico City Metropolitan Area (MCMA during the spring of 2003. Differences between Easter week and more typical weeks are evaluated. The use of CO-CHOCHO as HCHO tracers is more suitable for differentiating primary and secondary sources than CO-O3. The application of the CO-O3 tracer pair to mobile laboratory data suggests a potential in-city source of background HCHO. A significant amount of HCHO observed in the MCMA is associated with primary emissions.

  4. Photochemical ozone and nitric oxide formation in air-nitrogen dioxide mixtures containing sulfur dioxide or chlorine

    Energy Technology Data Exchange (ETDEWEB)

    Wallace, J.S.; Springer, G.S.; Stedman, D.H.

    1980-01-01

    The effects of sulfur dioxide and chlorine on ozone and nitric oxide concentrations in nitrogen dioxide-air mixtures were studied. The presence of 0-10 ppM SO/sub 2/ produced no change in the air mixture. Addition of 1-15 ppm chlorine increased the ozone concentration in the air mixture. A reaction model describing the interactions of chlorine and NO/sub 2/ is presented. (1 diagram, 6 graphs, 30 references, 3 tables)

  5. Water-Mediated Photochemical Treatments for Low-Temperature Passivation of Metal-Oxide Thin-Film Transistors.

    Science.gov (United States)

    Heo, Jae Sang; Jo, Jeong-Wan; Kang, Jingu; Jeong, Chan-Yong; Jeong, Hu Young; Kim, Sung Kyu; Kim, Kwanpyo; Kwon, Hyuck-In; Kim, Jaekyun; Kim, Yong-Hoon; Kim, Myung-Gil; Park, Sung Kyu

    2016-04-27

    The low-temperature electrical passivation of an amorphous oxide semiconductor (AOS) thin-film transistor (TFT) is achieved by a deep ultraviolet (DUV) light irradiation-water treatment-DUV irradiation (DWD) method. The water treatment of the first DUV-annealed amorphous indium-gallium-zinc-oxide (a-IGZO) thin film is likely to induce the preferred adsorption of water molecules at the oxygen vacancies and leads to subsequent hydroxide formation in the bulk a-IGZO films. Although the water treatment initially degraded the electrical performance of the a-IGZO TFTs, the second DUV irradiation on the water-treated devices may enable a more complete metal-oxygen-metal lattice formation while maintaining low oxygen vacancies in the oxide films. Overall, the stable and dense metal-oxygen-metal (M-O-M) network formation could be easily achieved at low temperatures (below 150 °C). The successful passivation of structural imperfections in the a-IGZO TFTs, such as hydroxyl group (OH-) and oxygen vacancies, mainly results in the enhanced electrical performances of the DWD-processed a-IGZO TFTs (on/off current ratio of 8.65 × 10(9), subthreshold slope of 0.16 V/decade, an average mobility of >6.94 cm(2) V(-1) s(-1), and a bias stability of ΔVTH < 2.5 V), which show more than a 30% improvement over the simple DUV-treated a-IGZO TFTs.

  6. Preferential Oxidation of Carbon Monoxide in Excess Hydrogen over Au/Co3O4- CeO2 Catalysts

    Institute of Scientific and Technical Information of China (English)

    2005-01-01

    Au/Co3O4-CeO2 mixed-oxide catalysts were shown experimentally to be highly active and selective for the oxidation of CO in hydrogen-rich mixture. Activity was markedly influenced by the composition of the support, aging temperature and Au-loading temperature. It provided that single-step removal of CO from hydrogen-rich stream both in the absence and presence of CO2 and H2O to a PEMFC tolerant level. It was found that catalytic activity is greatly affected by adding CO2 in the mixture and increased by farther adding H2O. It meants H2O has the effect to rise catalytic activity. Moreover,it shows better stability with reaction time for the preferential CO oxidation.

  7. Determination of thiomersal by flow injection coupled with microwave-assisted photochemical online oxidative decomposition of organic mercury and cold vapor atomic fluorescence spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Campanella, Beatrice; Onor, Massimo; Mascherpa, Marco Carlo; D’Ulivo, Alessandro [National Research Council of Italy, C.N.R., Istituto di Chimica dei Composti Organo Metallici-ICCOM-UOS Pisa, Area di Ricerca, Via G. Moruzzi 1, 56124 Pisa (Italy); Ferrari, Carlo [National Research Council of Italy, C.N.R., Istituto Nazionale di Ottica, INO–UOS Pisa, Area di Ricerca, Via G. Moruzzi 1, 56124 Pisa (Italy); Bramanti, Emilia, E-mail: bramanti@pi.iccom.cnr.it [National Research Council of Italy, C.N.R., Istituto di Chimica dei Composti Organo Metallici-ICCOM-UOS Pisa, Area di Ricerca, Via G. Moruzzi 1, 56124 Pisa (Italy)

    2013-12-04

    Graphical abstract: -- Highlights: •Thiomersal was determined on line using FI-MW/UV-CVGAFS. •MW/UV allows a “green” on line oxidation of organic mercury to Hg{sup II}. •Each measure requires less than 5 min with a LOD of 3 ng mL{sup −1} (as mercury). •Hg concentration in commercial ophthalmic solutions ranges between 7.5 and 59.0 μg mL{sup −1}. -- Abstract: We developed a flow injection (FI) method for the determination of thiomersal (sodium ethylmercurithiosalicylate, C{sub 9}H{sub 9}HgNaO{sub 2}S) based on the UV/microwave (MW) photochemical, online oxidation of organic mercury, followed by cold vapor generation atomic fluorescence spectrometry (CVG-AFS) detection. Thiomersal was quantitatively converted in the MW/UV process to Hg(II), with a yield of 97 ± 3%. This reaction was followed by the reduction of Hg(II) to Hg(0) performed in a knotted reaction coil with NaBH{sub 4} solution, and AFS detection in an Ar/H{sub 2} miniaturized flame. The method was linear in the 0.01–2 μg mL{sup −1} range, with a LOD of 0.003 μg mL{sup −1}. This method has been applied to the determination of thiomersal in ophthalmic solutions, with recoveries ranging between 97% and 101%. We found a mercury concentration in commercial ophthalmic solutions ranging between 7.5 and 59.0 μg mL{sup −1}.

  8. Actions and interactions of nitric oxide, carbon monoxide and hydrogen sulphide in the cardiovascular system and in inflammation--a tale of three gases!

    Science.gov (United States)

    Li, Ling; Hsu, Anna; Moore, Philip K

    2009-09-01

    Nitric oxide (NO), carbon monoxide (CO) and hydrogen sulphide (H(2)S) together make up a family of biologically active gases (the so-called 'gaseous triumvirate') with an increasingly well defined range of physiological effects plus roles to play in a number of disease states. Over the years, most researchers have concentrated their attention on understanding the part played by a single gas in one or more body systems. It is becoming more clear that all three gases are synthesised naturally in the body, often by the same cells within the same organs, and that all three gases exert essentially similar biological effects albeit via different mechanisms. Within the cardiovascular system, for example, all are vasodilators, promote angiogenesis and vascular remodelling and are protective towards tissue damage in for example, ischaemia-reperfusion injury in the heart. Similarly, all exhibit complex effects in inflammation with both pro- and anti-inflammatory effects recognised. It seems likely that cell function is controlled not by the activity of single gases working in isolation but by the concerted activity of all three of these gases working together.

  9. Rhodium based clusters for oxygen reduction and hydrogen oxidation in 0.5 M H2SO4, tolerant to methanol and carbon monoxide, respectively

    Energy Technology Data Exchange (ETDEWEB)

    Uribe-Godinez, J.; Jimenez-Sandoval, O.; Borja-Arco, E.; Altamirano-Gutierrez, A. [Centro de Investigacion y de Estudios Avanzados del Instituto Politecnico Nacional, Queritaro (Mexico); Castellanos, R.H. [Centro de Investigacion en Ciencia Aplicada y Tecnologia Avanzada-Queretaro, Queretaro (Mexico)

    2008-07-01

    Rhodium (Rh6(CO)16) and novel Rh-based clusters were prepared using thermolysis techniques under different conditions in N2 and H2 reaction media, as well as in n-nonane, o-xylene, 1,2-dichlorobenzene and dimethylsulfoxide. The clusters were used as novel electrocatalysts for oxygen reduction reaction (ORR) in the absence and presence of 1.0 and 2.0 M methanol solutions. The catalysts were also used for hydrogen oxidation reaction (HOR) with pure hydrogen (H2) and in the presence of carbon monoxide (CO). Rotating disk electrode measurements were used to analyze the materials. The study showed that the electrocatalyst support ratio plays a significant role in the electrochemical behaviour of the materials. Rh6(CO)16 and Rh2(1,2-DCB) presented the best electrocatalytic behaviour for ORR and HOR in the absence and presence of methanol and CO. The study demonstrated that the rhodium-based materials are capable of performing ORR and HOR while being tolerant of both methanol and CO. 3 refs., 3 figs.

  10. Effect of varying alveolar oxygen partial pressure on diffusing capacity for nitric oxide and carbon monoxide, membrane diffusing capacity and lung capillary blood volume.

    Science.gov (United States)

    Borland, C D; Cox, Y

    1991-12-01

    1. To examine the effect of varying oxygen partial pressure (PAO2) on nitric oxide (DLNO) and carbon monoxide (DLCO) diffusing capacity (transfer factor), 10 subjects performed combined DLCO/DLNO measurements with the inspired mixture made up with three different oxygen concentrations (25%, 18% and 15%) to give PAO2 values of 12-20 kPa. 2. A novel method is described for calculating membrane diffusing capacity (DM) and pulmonary capillary volume (Qc) from DLNO and DLCO. 3. The mean DMCO was 52.89 mmol min-1 kPa-1 and Qc was 0.056 litre. Reducing PAO2 from 20 to 12 kPa resulted in an increase in DLCO = -0.124 (O2%) + 11.67 (P less than 0.001) and a fall in DLNO = 0.538 (O2%) + 32.01 (P less than 0.001) and a fall in DLNO/DLCO = 0.107 (O2%) + 2.52 (P less than 0.001). DM (P = 0.59) and Qc (P = 0.64) also tended to fall with falling PAO2. 4. It appears more likely that the minor reduction in DLNO that we have observed with falling PAO2 is due to diffusion rather than reaction limitation.

  11. Lung diffusing capacity for nitric oxide and carbon monoxide in relation to morphological changes as assessed by computed tomography in patients with cystic fibrosis

    Directory of Open Access Journals (Sweden)

    Nowak Dennis

    2009-06-01

    Full Text Available Abstract Background Due to large-scale destruction, changes in membrane diffusion (Dm may occur in cystic fibrosis (CF, in correspondence to alterations observed by computed tomography (CT. Dm can be easily quantified via the diffusing capacity for nitric oxide (DLNO, as opposed to the conventional diffusing capacity for carbon monoxide (DLCO. We thus studied the relationship between DLNO as well as DLCO and a CF-specific CT score in patients with stable CF. Methods Simultaneous single-breath determinations of DLNO and DLCO were performed in 21 CF patients (mean ± SD age 35 ± 9 y, FEV1 66 ± 28%pred. Patients also underwent spirometry and bodyplethysmography. CT scans were evaluated via the Brody score and rank correlations (rS with z-scores of functional measures were computed. Results CT scores correlated best with DLNO (rS = -0.83; p S = -0.63; p CO (rS = -0.79; p NO were significantly lower than for DLCO (p 1, IVC or bodyplethysmographic (e.g., SRaw, RV/TLC indices were weaker than for DLNO or DLCO but most of them were also significant (p Conclusion In this cross sectional study in patients with CF, DLNO and DLCO reflected CT-morphological alterations of the lung better than other measures. Thus the combined diffusing capacity for NO and CO may play a future role for the non-invasive, functional assessment of structural alterations of the lung in CF.

  12. Acetaldehyde as an Intermediate in the Electroreduction of Carbon Monoxide to Ethanol on Oxide-Derived Copper

    DEFF Research Database (Denmark)

    Bertheussen, Erlend; Verdaguer Casadevall, Arnau; Ravasio, Davide

    2016-01-01

    Oxide-derived copper (OD-Cu) electrodes exhibit unprecedented CO reduction performance towards liquid fuels, producing ethanol and acetate with >50 % Faradaic efficiency at −0.3 V (vs. RHE). By using static headspace-gas chromatography for liquid phase analysis, we identify acetaldehyde as a mino...

  13. Electro-oxidation of carbon monoxide and methanol on bare and Pt-modified Ru(1010) electrodes.

    Science.gov (United States)

    Pinheiro, A L N; Zei, M S; Ertl, G

    2005-03-21

    The activity towards CO and methanol electrooxidation of bare and platinum-modified Ru(1010) surfaces has been investigated. The structure/morphology and composition of the modified surfaces were characterized using electron diffraction techniques (LEED, RHEED) and Auger spectroscopy. The bare Ru(1010) surface exhibits a higher catalytic activity towards CO electrooxidation than the Ru(0001) surface due to the lower oxidation potential of the former surface. The early stages of surface oxidation lead to disordering of the surface and further enhancing of the electrocatalytic activity. Electrodeposition of Pt on Ru(1010) leads to epitaxial growth via a Volmer-Weber growth mode. The Pt clusters grow preferentially with the (311) plane parallel to the substrate surface with (011) rows in the layers in contact with the substrate compressed by about 3% with respect to bulk Pt, in order to match with the (1210) rows of the Ru(1010) surface. This compression leads to enhanced catalytic activity towards CO oxidation for thin Pt deposits whereas for large deposited Pt particles the dominating factor for the catalytic enhancement is the higher concentration of surface defects. On the other hand, in the case of methanol oxidation, the dominant factor in determining the catalytic activity is the concentration of adjacent Pt-Ru sites, although surface defects play an important role in the methanol dehydrogenation steps.

  14. Oxidation of carbon monoxide, hydrogen peroxide and water at a boron doped diamond electrode: the competition for hydroxyl radicals.

    Science.gov (United States)

    Kisacik, Izzet; Stefanova, Ana; Ernst, Siegfried; Baltruschat, Helmut

    2013-04-07

    Boron doped diamond (BDD) electrodes have an extremely high over-voltage for oxygen evolution from water, which favours its use in oxidation processes of other compounds at high potentials. We used a rotating ring disc (RRDE) assembly and differential electrochemical mass spectrometry (DEMS) in order to monitor the consumption or the production of species in the course of the electrode processes. By intercepting the intermediate of the electrochemical water oxidation with chemical reactions we demonstrate clearly, albeit indirectly, that in the water oxidation process at BDD above 2.5 V the first step is the formation of ˙OH radicals. The electro-oxidation of CO to CO2 at BDD electrodes proceeds only via a first attack by ˙OH radicals followed by a further electron transfer to the electrode. At potentials below the onset of oxygen evolution from water, H2O2 is oxidised by a direct electron transfer to the BDD electrode, while at higher potentials, two different reactions paths compete for the ˙OH radicals formed in the first electron transfer from water: one, where these ˙OH radicals react with each other followed by further electron transfers leading to O2 on the one hand and one, where ˙OH radicals react with other species like H2O2 or CO with subsequent electron transfers on the other hand.

  15. Acetaldehyde as an Intermediate in the Electroreduction of Carbon Monoxide to Ethanol on Oxide-Derived Copper

    DEFF Research Database (Denmark)

    Bertheussen, Erlend; Verdaguer Casadevall, Arnau; Ravasio, Davide

    2016-01-01

    Oxide-derived copper (OD-Cu) electrodes exhibit unprecedented CO reduction performance towards liquid fuels, producing ethanol and acetate with >50 % Faradaic efficiency at −0.3 V (vs. RHE). By using static headspace-gas chromatography for liquid phase analysis, we identify acetaldehyde as a mino...

  16. O{sub 2}-mediated oxidation of ferrous nitrosylated human serum heme-albumin is limited by nitrogen monoxide dissociation

    Energy Technology Data Exchange (ETDEWEB)

    Ascenzi, Paolo, E-mail: ascenzi@uniroma3.it [Interdepartmental Laboratory of Electron Microscopy, University Roma Tre, Via della Vasca Navale 79, I-00146 Roma (Italy); National Institute for Infectious Diseases I.R.C.C.S. ' Lazzaro Spallanzani' , Via Portuense 292, I-00149 Roma (Italy); Gullotta, Francesca; Gioia, Magda; Coletta, Massimo [Department of Experimental Medicine and Biochemical Sciences, University of Roma ' Tor Vergata' , Via Montpellier 1, I-00133 Roma (Italy); Interuniversity Consortium for the Research on the Chemistry of Metals in Biological Systems, Piazza Umberto I 1, I-87100 Bari (Italy); Fasano, Mauro [Department of Structural and Functional Biology, and Center of Neuroscience, University of Insubria, Via Alberto da Giussano 12a, I-21052 Busto Arsizio, VA (Italy)

    2011-03-04

    Research highlights: {yields} Human serum heme-albumin displays globin-like properties. {yields} O{sub 2}-mediated oxidation of ferrous nitrosylated human serum heme-albumin. {yields} Allosteric modulation of human serum heme-albumin reactivity. {yields} Rifampicin is an allosteric effector of human serum heme-albumin. {yields} Human serum heme-albumin is a ROS and NOS scavenger. -- Abstract: Human serum heme-albumin (HSA-heme-Fe) displays globin-like properties. Here, kinetics of O{sub 2}-mediated oxidation of ferrous nitrosylated HSA-heme-Fe (HSA-heme-Fe(II)-NO) is reported. Values of the first-order rate constants for O{sub 2}-mediated oxidation of HSA-heme-Fe(II)-NO (i.e., for ferric HSA-heme-Fe formation) and for NO dissociation from HSA-heme-Fe(II)-NO (i.e., for NO replacement by CO) are k = 9.8 x 10{sup -5} and 8.3 x 10{sup -4} s{sup -1}, and h = 1.3 x 10{sup -4} and 8.5 x 10{sup -4} s{sup -1}, in the absence and presence of rifampicin, respectively, at pH = 7.0 and T = 20.0 {sup o}C. The coincidence of values of k and h indicates that NO dissociation represents the rate limiting step of O{sub 2}-mediated oxidation of HSA-heme-Fe(II)-NO. Mixing HSA-heme-Fe(II)-NO with O{sub 2} does not lead to the formation of the transient adduct(s), but leads to the final ferric HSA-heme-Fe derivative. These results reflect the fast O{sub 2}-mediated oxidation of ferrous HSA-heme-Fe and highlight the role of drugs in modulating allosterically the heme-Fe-atom reactivity.

  17. Characterization and carbon monoxide oxidation activity of La1-ySryCr1-xRuxO3 perovskites

    Directory of Open Access Journals (Sweden)

    C. MARINOVA

    2000-01-01

    Full Text Available The oxidation of CO over La1-ySryCr1-xRuxO3 perovskite type oxides with y=0.3 and 0 £ x £ 0.100 have been studied. X-ray fluorescence analysis confirmed that content of elements in the bulk corresponds to the established nominal perovskite stoichiometry, indicating that no significant oxidation of ruthenium into volatile polyvalent oxides with their consequented escape from the sample occurred in air up to the temperature of 1000°C. According to X-ray diffraction analysis, all sampls achieved the perovskite hexagonal with the presence of some SrCrO4. X-ray photoelectron spectroscopy analysis of ruthenium samples shows higher Ru and Sr surface concentraitions than in the bulk. The binding energy for Ru3p is virtually the same in all samples and consistent with that of Ru4+ (463.6-464.3eV. Kinetic studies were performed in a differential recycle reactor with a recycling ratio 80. The results show that substitution of Ru4+ for Cr3+ in La1-ySryCrO3 leads to a significant increase in both the activity and the activation energy. The global CO oxidation rate, referred on the BET surface area, correlates with the surface Ru4+ atomic concentraiton. Hence, the activity reflect the surface enrichment in ruthenium. Moreover, an identical apparent activation energy E = 93 kJ/mol and the same specific rate per ruthenium surface ion were obtained for samples with a Ru content x ³ 0.05 suggest that exposed Ru4+ ions mainly participate in the reaction.

  18. The carbon monoxide oxidation reaction over controlled catalyst structures based on gold/cerium dioxide thin films

    Science.gov (United States)

    Zhou, Zheng

    Gold-based catalysts have attracted significant research interest due to their remarkably high activity for many important reactions, including the low-temperature CO oxidation reaction. Despite extensive studies, several fundamental issues in the understanding of CO oxidation over supported gold catalysts are unresolved. The locus and nature of active sites, including the role of the metal, metal oxide support, and their interface, remain controversial. The objectives of this thesis were to study CO oxidation on Au/CeO2 catalysts that were prepared using thin film techniques so as to form geometrically controlled structures in contrast to the typical supported nanoparticle systems. Using these structures enables one to evaluate the contribution of metal oxide support (CeO2), and locate and identify the active sites in the Au/CeO2 system. In particular, the specific contribution to the reaction by the metal/oxide interface, the role and nature of the vacancies in the oxide, the role of the dimensions of the Au and ceria, and the role of stress in the gold films have been investigated. Two catalyst systems, each employing nanoscale films, were investigated. One was formed from a "single layer" of metal or oxide in the form of an extended surface that was then decorated with a thin layer of the other catalyst partner; the second approach was a study of multilayer metal/oxide structures to assess the role of the metal/metal oxide interface. More specifically the reaction sites formed at the three-phase boundary of metal, metal oxide and gas. In the first case, a Au film (4.5nm) was prepared using vapor deposition on SiO2/Si (100) substrates. The gold coalesced into discrete islands with large lateral size (20-100nm) and was found to be only weakly active. The extremely low activity of gold with large lateral extended surface has been attributed to the lack of uncoordinated gold atoms on this type of gold surface. Subsequently decorating the gold with nanosized ceria

  19. Effect of Organic Capping Layers over Monodisperse Platinum Nanoparticles upon Activity for Ethylene Hydrogenation and Carbon Monoxide Oxidation

    Energy Technology Data Exchange (ETDEWEB)

    Kuhn, John N.; Tsung, Chia-Kuang; Huang, Wenyu; Somorjai, Gabor A.

    2009-03-24

    The influence of oleylamine (OA), trimethyl tetradecyl ammonium bromide (TTAB), and polyvinlypyrrolidone (PVP) capping agents upon the catalytic properties of Pt/silica catalysts was evaluated. Pt nanoparticles that were 1.5 nm in size were synthesized by the same procedure (ethylene glycol reduction under basic conditions) with the various capping agents added afterward for stabilization. Before examining catalytic properties for ethylene hydrogenation and CO oxidation, the Pt NPs were deposited onto mesoporous silica (SBA-15) supports and characterized by transmission electron microscopy (TEM), H{sub 2} chemisorption, and elemental analysis (ICP-MS). PVP- and TTAB-capped Pt yielded mass-normalized reaction rates that decreased with increasing pretreatment temperature, and this trend was attributed to the partial coverage of the Pt surface with decomposition products from the organic capping agent. Once normalized to the Pt surface area, similar intrinsic activities were obtained regardless of the pretreatment temperature, which indicated no influence on the nature of the active sites. Consequently, a chemical probe technique using intrinsic activity for ethylene hydrogenation was demonstrated as an acceptable method for estimating the metallic surface areas of Pt. Amine (OA) capping exhibited a detrimental influence on the catalytic properties as severe deactivation and low activity were observed for ethylene hydrogenation and CO oxidation, respectively. These results were consistent with amine groups being strong poisons for Pt surfaces, and revealed the need to consider the effects of capping agents on the catalytic properties.

  20. Large-scale and green synthesis of octahedral flower-like cupric oxide nanocrystals with enhanced photochemical properties

    Energy Technology Data Exchange (ETDEWEB)

    Li, Shi-Kuo; Pan, Yu-Yi; Wu, Mi; Huang, Fang-Zhi; Li, Chuan-Hao, E-mail: lichuanhao1983@163.com; Shen, Yu-Hua, E-mail: s_yuhua@163.com

    2014-10-01

    Graphical abstract: - Highlights: • A green method is reported for large-scale synthesis of CuO nanocrystals via a coordination-deposition technique. • Flower-like nanostructure can be rationally tailored by adjusting reaction parameters. • Flower-like nanostructure can be obtained in a wide reaction solution volume range. • Uniform flower-like nanocrystal film assembled by oil–water interfacial self-assembly method exhibits excellent PEC performance. - Abstract: In this work, a large-scale and green method is reported for the facile synthesis of octahedral flower-like CuO nanocrystals via a coordination-deposition route by using Fehling regents. Not any harmful organic chemicals were used during the reaction period. The obtained hierarchical nanostructure can be rationally tailored by varying the concentration of tartrate ions and reaction time. The typical flower-like CuO nanocrystals in the range of 200–250 nm are consisted of numerous small crystalline whiskers, which present a porous surface with a specific surface area of 32.12 m{sup 2}/g and a narrow band gap of 1.5 eV. Importantly, the flower-like CuO nanocrystals show an enhanced photocatalytic activity toward decomposing Rhodamine B (RhB) molecules. The degradation rate is about 87.9% in 40 min under visible light irradiation, which is about 2.5 times for the commercial CuO powers (35.2%). Moreover, the uniform flower-like monolayered CuO film exhibits an excellent photoelectrochemical (PEC) performance with a maximum photocurrent density of 58.8 μA/cm{sup 2}, which is nearly five times higher than the commercial CuO film. This novel synthesis approach provides a large-scale and green protocol for synthesizing hierarchical metal oxide nanocrystals that are useful for photocatalysis, PEC water splitting and photovoltaic device.

  1. Carbon Monoxide Information Center

    Medline Plus

    Full Text Available ... Estimates OCTOBER 13, 2015 Incidents, Deaths, and In-Depth Investigations Associated with Non-Fire Carbon Monoxide from Engine-Driven Generators and ... Engine-Driven Tools, 2004–2014 JANUARY 08, 2015 Non-Fire Carbon Monoxide Deaths Associated with the Use of Consumer Products 2011 Annual Estimates View All ... Inside CPSC Accessibility ...

  2. Hydrogenation of carbon monoxide over the mixed catalysts composed of cobalt-nickel/manganese oxide-zirconium oxide and zeolite catalysts

    Energy Technology Data Exchange (ETDEWEB)

    Ishihara, Tatsumi; Iwakuni, Hideharu; Eguchi, Koichi; Arai, Hiromichi (Kyushu Univ., Fukuoka (Japan))

    1991-08-15

    Mechanical mixtures of Co-Ni/MnO-ZrO2 and zeolite were used as catalysts for the selective synthesis of gasoline by carbon monoxide hydrogenation. Formation of branched alkanes was promoted, but that of hydrocarbons higher than a carbon number of 10 was suppressed by a combination with zeolite. The reactivity of zeolite for higher hydrocarbons has the decisive role in the product distribution as result of using these mixed catalysts, and thus the product distribution strongly depends on the type of zeolite. Since the hydrogenolysis of higher hydrocarbons proceeds on the strong acid sites, the formation of branched alkanes was promoted by increasing the aluminium content in the zeolite. Ammonia temperature-programmed desorption suggests that increasing the aluminium content in the zeolite increases the number of strong acid sites, but weakens the average strength of the acid sites. Pentasil zeolite with an aluminium content of 1.32 mmolg{sup -1} is effective for enhancing the yield of gasoline as well as its octane number. 8 figs., 1 tab., 20 refs.

  3. Effects of Tai Chi exercise on blood pressure and plasma levels of nitric oxide, carbon monoxide and hydrogen sulfide in real-world patients with essential hypertension.

    Science.gov (United States)

    Pan, Xiaogui; Zhang, Yi; Tao, Sai

    2015-01-01

    Objective was to investigate the effects of Tai Chi exercise on nitric oxide (NO), carbon monoxide (CO) and hydrogen sulfide (H2S) levels, and blood pressure (BP) in patients with essential hypertension (EH). EH patients were assigned to the Tai Chi exercise group (HTC, n = 24), and hypertension group (HP, n = 16) by patients' willingness. Healthy volunteers matched for age and gender were recruited as control (NP, n = 16). HTC group performed Tai Chi (60 min/d, 6 d/week) for 12 weeks. Measurements (blood glucose, cholesterol, NO, CO, H2S and BP) were obtained at week 0, 6, and 12. SBP, MAP, and low-density lipoprotein cholesterol levels decreased, and high-density lipoprotein cholesterol levels increased by week 12 in the HTC group (all p < 0.05 versus baseline). Plasma NO, CO, and H2S levels in the HTC group were increased after 12 weeks (all p < 0.05 versus baseline). SBP, DBP and MAP levels were significantly lower in the HTC than in the HP group (all p < 0.05). However, no changes were observed in the HP and NP groups. Correlations were observed between changes in SBP and changes in NO, CO and H2S (r = -0.45, -0.51 and -0.46, respectively, all p < 0.05), and between changes in MAP and changes in NO, CO and H2S (r = -0.36, -0.45 and -0.42, respectively, all p < 0.05). In conclusion, Tai Chi exercise seems to have beneficial effects on BP and gaseous signaling molecules in EH patients. However, further investigation is required to understand the exact mechanisms underlying these observations, and to confirm these results in a larger cohort.

  4. Effect of varying the combustion parameters on the emissions of carbon monoxide and nitrogen oxides in the exhaust gases from propane-fueled vehicles.

    Science.gov (United States)

    Roberge, B

    2000-05-01

    Propane-fueled forklifts are one source of carbon monoxide (CO) contamination of workplace air. The previous study carried out by the Quebec Occupational Health and Safety Research Institute dealt with worker exposure to CO during forklift use in buildings. It recommends that exhaust gas emissions be kept below a 1 percent concentration. However, this control has not produced a significant reduction in worker exposure to CO, when factors (ventilation, type of work tasks, and management of vehicle fleet) specific to companies are taken into account. Consequently, a reduction in CO emissions below the threshold of 0.3 percent should be considered. The experience acquired with propane-fueled ice resurfacers can be used to determine the effect of combustion parameters on exhaust gas emissions. It is known that a reduction in CO emissions from ice resurfacers resulted in the appearance of nitrogen oxides (NOx) and eventually in nitrogen dioxide (NO2) poisoning. Few publications present NOx results in relation to the CO measured in the exhaust gases of propane-fueled vehicles. The objective of this study is to define the level to which CO emissions can be reduced without increasing NOx concentrations. This real-situation study quantified the CO, NO, and NOx in the exhaust gases of a fleet of propane-fueled forklifts in relation to the mixture ratio. The results show the impact of the motor speed and mixture ratio on the CO, NO, and NO2 concentrations. They confirm an increase in NOx concentrations when CO concentrations are reduced. They also show that proper maintenance of forklifts combined with optimal adjustments can reduce CO and NOx emissions. The study proposes a compromise between CO and NOx emissions by taking into account worker health and safety as well as vehicle performance. Monitoring must be done to control air quality in work areas and worker exposure to CO and NO2. A forklift preventive maintenance program and general building ventilation are the favored

  5. The Influence of Base Metal (M Oxidation State in Au-M-O/TiO2 Systems on Their Catalytic Activity in Carbon Monoxide Oxidation

    Directory of Open Access Journals (Sweden)

    Katarzyna Samson

    2011-12-01

    Full Text Available Base metal promoted gold/titania catalysts were synthesized, characterized and tested in CO oxidation reaction. Catalysts containing dopant metals in higher oxidation states exhibited higher activity than catalysts containing dopants in reduced states. The activity of fresh catalysts promoted by Cu, Fe and Ni was similar to the unpromoted one, but treatment in reducing and oxidizing atmospheres revealed the supremacy of the copper promoted catalyst. The sequential deposition method proved to be better than the co-deposition—precipitation method. An attempt to explain these differences using XPS, FTIR and H2 TPR was performed.

  6. The role and interactions of nitric oxide (NO), carbon monoxide (CO), and prostanoids in the pathogenesis of postoperative ileus in rats.

    Science.gov (United States)

    Korolkiewicz, R P; Sein-Anand, J; Ruczyński, J; Rekowski, P; Bieniaszewski, L; Chodorowski, Z; Petrusewicz, J; Ujda, M; Dabkowski, J; Bitel, M; Kato, S; Takeuchi, K

    2004-01-01

    The effects of heme oxygenase (HO) inhibitors, zinc-protoporphyrin-IX (ZnPP-IX), and tin protoporphyrin-IX (SnPP-IX) and their interactions with L-arginine/nitric oxide synthase (NOS) and cyclooxygenase (COX) pathways were investigated in postoperative ileus in rats. Intestinal transit was measured as Evans blue migration after skin incision, laparotomy or laparotomy plus gut evisceration and handling. Laparotomy and small intestinal manipulations increased blood plasma nitrites/nitrates level 1.88-fold. N(omega)-nitro-L-arginine methyl ester, indomethacin, a selective COX-1 blocker (resveratrol) and COX-2 antagonists (nimesulide, DuP-697, NS-398) reversed the additional inhibitory effects of gut manipulation subsequent to laparotomy. In contrast, N-(3-(aminomethyl)benzyl)acetamidine or S-methylisothiourea, highly selective inducible NOS blockers, remained ineffective. ZnPP-IX and SnPP-IX overturned the effects of laparotomy on dye propulsion, but were only partially effective after laparotomy and gut handling attenuating the additional inhibitory influences of gut manipulation, the intestinal transit reaching 89.21%, 92.87%, 53.46%, and 48.56% of respective controls transit. Salutary effects of L-NAME, ZnPP-IX, and SnPP-IX were dose-dependent, L-arginine or hemin (HO substrate) sensitive. Administration of indomethacin and resveratrol subsequent to SnPP-IX reversed the inhibitory effects of laparotomy and manipulation, amounting to 93.91% and 87.43% of controls. On the other hand, L-NAME injected after SnPP-IX abolished the salutary effects of the latter, study dye migration reached 25.18% of control rat. Therefore we demonstrated that nitric oxide, carbon monoxide, and prostanoids play a role in the pathogenesis of postoperative ileus albeit in different mechanisms. Laparotomy stimulated HO activity, whereas gut manipulation led to an excessive constitutive NOS stimulation accompanied by augmented prostanoid synthesis by COX-1. Unaffected synthesis of either NO

  7. Cost of photochemical machining

    OpenAIRE

    Roy, Rajkumar; Allen, David; Zamora, Oscar

    2004-01-01

    Photochemical machining (PCM), also known as photoetching, photofabrication or photochemical milling, is a non-traditional manufacturing method based on the combination of photoresist imaging and chemical etching. PCM uses techniques similar to those employed for the production of printed circuit boards and silicon integrated circuits. The PCM industry plays a valuable worldwide role in the production of metal precision parts and decorative items. Parts produced by PCM are t...

  8. Evidence for oxidative stress in the developing cerebellum of the rat after chronic mild carbon monoxide exposure (0.0025% in air

    Directory of Open Access Journals (Sweden)

    Lopez Ivan A

    2009-05-01

    Full Text Available Abstract Background The present study was designed to test the hypothesis that chronic very mild prenatal carbon monoxide (CO exposure (25 parts per million subverts the normal development of the rat cerebellar cortex. Studies at this chronic low CO exposure over the earliest periods of mammalian development have not been performed to date. Pregnant rats were exposed chronically to CO from gestational day E5 to E20. In the postnatal period, rat pups were grouped as follows: Group A: prenatal exposure to CO only; group B: prenatal exposure to CO then exposed to CO from postnatal day 5 (P5 to P20; group C: postnatal exposure only, from P5 to P20, and group D, controls (air without CO. At P20, immunocytochemical analyses of oxidative stress markers, and structural and functional proteins were assessed in the cerebellar cortex of the four groups. Quantitative real time PCR assays were performed for inducible (iNOS, neuronal (nNOS, and endothelial (eNOS nitric oxide synthases. Results Superoxide dismutase-1 (SOD1, SOD2, and hemeoxygenase-1 (HO-1 immunoreactivity increased in cells of the cerebellar cortex of CO-exposed pups. INOS and nitrotyrosine immunoreactivity also increased in blood vessels and Purkinje cells (PCs of pups from group-A, B and C. By contrast, nNOS immunoreactivity decreased in PCs from group-B. Endothelial NOS immunoreactivity showed no changes in any CO-exposed group. The mRNA levels for iNOS were significantly up-regulated in the cerebellum of rats from group B; however, mRNA levels for nNOS and eNOS remained relatively unchanged in groups A, B and C. Ferritin-H immunoreactivity increased in group-B. Immunocytochemistry for neurofilaments (structural protein, synapsin-1 (functional protein, and glutamic acid decarboxylase (the enzyme responsible for the synthesis of the inhibitory neurotransmitter GABA, were decreased in groups A and B. Immunoreactivity for two calcium binding proteins, parvalbumin and calbindin, remained

  9. Carbon Monoxide Information Center

    Medline Plus

    Full Text Available ... CONSUMER PRODUCT SAFETY COMMISSION Search CPSC Search Menu Home Recalls Recall List CPSC Recall API Recall Lawsuits ... and Bans Report an Unsafe Product Consumers Businesses Home Safety Education Safety Education Centers Carbon Monoxide Information ...

  10. Carbon Monoxide Information Center

    Medline Plus

    Full Text Available ... Safety Blogs: CO Safety More CO Blogs Research & Statistics JANUARY 07, 2016 Non-Fire Carbon Monoxide Deaths ... 2011 Annual Estimates View All CO-Related Injury Statistics and Technical Reports Related Links Recalls Safety Education ...

  11. Carbon Monoxide Information Center

    Medline Plus

    Full Text Available ... On Safety Blogs: CO Safety More CO Blogs Research & Statistics JANUARY 07, 2016 Non-Fire Carbon Monoxide ... Related Links Recalls Safety Education Regulations, Laws & Standards Research & Statistics Business & Manufacturing Small Business Resources OnSafety Blogs ...

  12. Carbon Monoxide Information Center

    Medline Plus

    Full Text Available ... Community Outreach Resource Center Toy Recall Statistics CO Poster Contest Pool Safely Business & Manufacturing Business & Manufacturing Business ... Featured Resources CPSC announces winners of carbon monoxide poster contest Video View the blog Clues You Can ...

  13. Carbon Monoxide Information Center

    Science.gov (United States)

    ... and Criminal Penalties Federal Court Orders & Decisions Research & Statistics Research & Statistics Technical Reports Injury Statistics NEISS Injury Data ... On Safety Blogs: CO Safety More CO Blogs Research & Statistics JANUARY 07, 2016 Non-Fire Carbon Monoxide Deaths ...

  14. Carbon Monoxide Information Center

    Medline Plus

    Full Text Available ... Statistics JANUARY 07, 2016 Non-Fire Carbon Monoxide Deaths Associated with the Use of Consumer Products 2012 Annual Estimates OCTOBER 13, 2015 Incidents, Deaths, and In-Depth Investigations Associated with Non-Fire ...

  15. Carbon Monoxide Information Center

    Medline Plus

    Full Text Available ... Unites States die every year from accidental non-fire related CO poisoning associated with consumer products, including ... CO Blogs Research & Statistics JANUARY 07, 2016 Non-Fire Carbon Monoxide Deaths Associated with the Use of ...

  16. Carbon Monoxide Information Center

    Medline Plus

    Full Text Available ... Import Safety International Recall Guidance Civil and Criminal Penalties Federal Court Orders & ... 07, 2016 Non-Fire Carbon Monoxide Deaths Associated with the Use of Consumer Products 2012 ...

  17. Carbon Monoxide Nonattainment Areas

    Data.gov (United States)

    U.S. Environmental Protection Agency — This data layer identifies areas in the U.S. where air pollution levels have not met the National Ambient Air Quality Standards (NAAQS) for Carbon Monoxide and have...

  18. Carbon Monoxide Information Center

    Medline Plus

    Full Text Available ... Unites States die every year from accidental non-fire related CO poisoning associated with consumer products, including ... CO Blogs Research & Statistics JANUARY 07, 2016 Non-Fire Carbon Monoxide Deaths Associated with the Use of ...

  19. Highly-resolved Modeling of Emissions and Concentrations of Carbon Monoxide, Carbon Dioxide, Nitrogen Oxides, and Fine Particulate Matter in Salt Lake City, Utah

    Science.gov (United States)

    Mendoza, D. L.; Lin, J. C.; Mitchell, L.; Ehleringer, J. R.

    2014-12-01

    Accurate, high-resolution data on air pollutant emissions and concentrations are needed to understand human exposures and for both policy and pollutant management purposes. An important step in this process is also quantification of uncertainties. We present a spatially explicit and highly resolved emissions inventory for Salt Lake County, Utah, and trace gas concentration estimates for carbon monoxide (CO), carbon dioxide (CO2), nitrogen oxides (NOx) and fine particles (PM2.5) within Salt Lake City. We assess the validity of this approach by comparing measured concentrations against simulated values derived from combining the emissions inventory with an atmospheric model. The emissions inventory for the criteria pollutants was constructed using the 2011 National Emissions Inventory (NEI). The spatial and temporal allocation methods from the Emission Modeling Clearinghouse data set are used to downscale the NEI data from annual to hourly scales and from county-level to 500 m x 500 m resolution. Onroad mobile source emissions were estimated by combining a bottom-up emissions calculation approach for large roadway links with a top-down spatial allocation approach for other roadways. Vehicle activity data for road links were derived from automatic traffic responder data. The emissions inventory for CO2 was obtained from the Hestia emissions data product at an hourly, building, facility, and road link resolution. The AERMOD and CALPUFF dispersion models were used to transport emissions and estimate air pollutant concentrations at an hourly temporal and 500 m x 500 m spatial resolution. Modeled results were compared against measurements from a mobile lab equipped with trace gas measurement equipment traveling on pre-determined routes in the Salt Lake City area. The comparison between both approaches to concentration estimation highlights spatial locations and hours of high variability/uncertainty. Results presented here will inform understanding of variability and

  20. Photochemical behaviour of phenylurea herbicides.

    Science.gov (United States)

    Amine-Khodja, Amina; Boulkamh, Abdelaziz; Boule, Pierre

    2004-02-01

    The photochemical behaviour of phenylurea herbicides in aqueous solution is highly dependent on the nature and position of substituents on the ring. Most of these herbicides are methylated on the urea moiety, the other substituents are usually halogens or methoxy groups. The main reaction involving the aromatic ring of unhalogenated phenylureas excited at wavelengths shorter than 300 nm is an intramolecular rearrangement, similar to photo-Fries rearrangement, whereas with halogenated derivatives, photohydrolysis is the main transformation pathway. In the particular case of para-halogenated phenylureas, the intermediate formation of a carbene is observed. When the urea moiety is substituted with a methoxyl group, demethoxylation is a competitive reaction. N-Demethylation or oxidation of methyl groups is also observed, but with a lower yield. Photooxidation of phenylureas can also be induced by photocatalysis, iron salts or humic substances. In the absence of water, the main route for phototransformation of diuron is the oxidation or elimination of methyl groups. It is entirely possible that a photochemical intermediate could turn out to be more toxic than the initial herbicide.

  1. Photochemical tissue bonding

    Science.gov (United States)

    Redmond, Robert W.; Kochevar, Irene E.

    2012-01-10

    Photochemical tissue bonding methods include the application of a photosensitizer to a tissue and/or tissue graft, followed by irradiation with electromagnetic energy to produce a tissue seal. The methods are useful for tissue adhesion, such as in wound closure, tissue grafting, skin grafting, musculoskeletal tissue repair, ligament or tendon repair and corneal repair.

  2. Additive and Photochemical Manufacturing of Copper

    Science.gov (United States)

    Yung, Winco K. C.; Sun, Bo; Meng, Zhengong; Huang, Junfeng; Jin, Yingdi; Choy, Hang Shan; Cai, Zhixiang; Li, Guijun; Ho, Cheuk Lam; Yang, Jinlong; Wong, Wai Yeung

    2016-12-01

    In recent years, 3D printing technologies have been extensively developed, enabling rapid prototyping from a conceptual design to an actual product. However, additive manufacturing of metals in the existing technologies is still cost-intensive and time-consuming. Herein a novel platform for low-cost additive manufacturing is introduced by simultaneously combining the laser-induced forward transfer (LIFT) method with photochemical reaction. Using acrylonitrile butadiene styrene (ABS) polymer as the sacrificial layer, sufficient ejection momentum can be generated in the LIFT method. A low-cost continuous wave (CW) laser diode at 405 nm was utilized and proved to be able to transfer the photochemically synthesized copper onto the target substrate. The wavelength-dependent photochemical behaviour in the LIFT method was verified and characterized by both theoretical and experimental studies compared to 1064 nm fiber laser. The conductivity of the synthesized copper patterns could be enhanced using post electroless plating while retaining the designed pattern shapes. Prototypes of electronic circuits were accordingly built and demonstrated for powering up LEDs. Apart from pristine PDMS materials with low surface energies, the proposed method can simultaneously perform laser-induced forward transfer and photochemical synthesis of metals, starting from their metal oxide forms, onto various target substrates such as polyimide, glass and thermoplastics.

  3. Additive and Photochemical Manufacturing of Copper.

    Science.gov (United States)

    Yung, Winco K C; Sun, Bo; Meng, Zhengong; Huang, Junfeng; Jin, Yingdi; Choy, Hang Shan; Cai, Zhixiang; Li, Guijun; Ho, Cheuk Lam; Yang, Jinlong; Wong, Wai Yeung

    2016-12-21

    In recent years, 3D printing technologies have been extensively developed, enabling rapid prototyping from a conceptual design to an actual product. However, additive manufacturing of metals in the existing technologies is still cost-intensive and time-consuming. Herein a novel platform for low-cost additive manufacturing is introduced by simultaneously combining the laser-induced forward transfer (LIFT) method with photochemical reaction. Using acrylonitrile butadiene styrene (ABS) polymer as the sacrificial layer, sufficient ejection momentum can be generated in the LIFT method. A low-cost continuous wave (CW) laser diode at 405 nm was utilized and proved to be able to transfer the photochemically synthesized copper onto the target substrate. The wavelength-dependent photochemical behaviour in the LIFT method was verified and characterized by both theoretical and experimental studies compared to 1064 nm fiber laser. The conductivity of the synthesized copper patterns could be enhanced using post electroless plating while retaining the designed pattern shapes. Prototypes of electronic circuits were accordingly built and demonstrated for powering up LEDs. Apart from pristine PDMS materials with low surface energies, the proposed method can simultaneously perform laser-induced forward transfer and photochemical synthesis of metals, starting from their metal oxide forms, onto various target substrates such as polyimide, glass and thermoplastics.

  4. Effect the conditions of the acid-thermal modification of clinoptilolite have on the catalytic properties of palladium-copper complexes anchored on it in the reaction of carbon monoxide oxidation

    Science.gov (United States)

    Rakitskaya, T. L.; Kiose, T. A.; Ennan, A. A.; Golubchik, K. O.; Oleksenko, L. P.; Gerasiova, V. G.

    2016-06-01

    The dependence of the physicochemical and structural-adsorption properties of natural and acid-thermal modified clinoptilolite, and of Pd(II)-Cu(II) catalysts based on them, on the duration of acid-thermal modification is investigated. The samples under study are described via XRD and thermal gravimetric (DTG and DTA) analysis, IR, DR UV-Vis, EPR spectroscopy, and water vapor adsorption. Values of both the specific surface area ( S sp) and pH of aqueous suspensions are determined. The resulting catalysts are tested in the reaction of low-temperature carbon monoxide oxidation with air oxygen. A conclusion is drawn about the nature of surface bimetallic Pd(II)-Cu(II) complexes. The greatest catalytic activity is shown by complexes based on clinoptilolite and modified with 3 M HNO3 for 0.5 and 1 h.

  5. Fabrication of copper decorated tungsten oxide–titanium oxide nanotubes by photochemical deposition technique and their photocatalytic application under visible light

    Energy Technology Data Exchange (ETDEWEB)

    Momeni, Mohamad Mohsen, E-mail: mm.momeni@cc.iut.ac.ir

    2015-12-01

    Graphical abstract: Schematic presentation of the pretreatment method of titanium sheets and producing process of WTNs and Cu/WTNs films on titanium foils. - Highlights: • WO{sub 3}–TiO{sub 2} nanotubes (WTNs) were synthesized by one-step electrochemical anodizing. • Copper decorated WO{sub 3}–TiO{sub 2} nanotubes (Cu/WTNs) were successfully prepared by photochemical deposition. • Photocatalytic activity of Cu/WTNs is higher than that of bare WTNs. • These photocatalysts showed good stability and it could be recycled several times without significant loss of its activity. - Abstract: Copper decorated WO{sub 3}–TiO{sub 2} nanotubes (Cu/WTNs) with a high photocatalytic activity were prepared by anodizing and photochemical deposition. Highly ordered WO{sub 3}–TiO{sub 2} nanotubes (WTNs) on pure titanium foils were successfully fabricated by electrochemical anodizing and copper deposited on these nanotubes (Cu/WTNs) by photoreduction method. The resulting samples were characterized by various methods. Only the anatase phase was detected by X-ray diffraction analysis. The presence of copper in the structure of thin films was confirmed by energy dispersive X-ray spectrometry and X-ray diffraction. The extension of optical absorption into the visible region of as-prepared films was indicated by UV/Vis spectroscopy. The degradation of methylene blue was used as a model reaction to evaluate the photocatalytic activity of the obtained samples. Results showed that the photocatalytic activity of Cu/WTNs samples is higher than bare WTNs sample. Kinetic research showed that the reaction rate constant of Cu/WTNs is approximately 2.5 times higher than the apparent reaction rate constant of bare WTNs. These results not only offer an economical method for constructing Cu/WTNs photocatalysts, but also shed new insight on the rational design of a low cost and high-efficiency photocatalyst for environmental remediation.

  6. Photochemical Age Determinations in the Phoenix Metropolitan Area

    Energy Technology Data Exchange (ETDEWEB)

    Kleinman, Lawrence I.; Daum, Peter H.; Lee, Y.- N.; Nunnermacker, L. J.; Springston, S. R.; Weinstein-Lloyd, J.; Hyde, P.; Doskey, Paul; Rudolph, Jochen; Fast, Jerome D.; Berkowitz, Carl M.

    2003-02-05

    An extensive VOC data set was gathered as part of a photochemical oxidant field campaign conducted in the Phoenix air basin in the late spring of 1998. Sampling was done at the surface and by aircraft at mid-boundary layer height; in regions with emission sources and downwind in the urban plume. VOC concentration ratios were used to calculate photochemical age, defined as the time integrated exposure of an air mass to OH radical. Based on the VOC ratios of 15 compounds (with OH reactivity varying between acetylene and p,m-xylene), we present estimates for photochemical age and dilution factors for several regions within the air basin. Geographic trends are in agreement with the expectation that pollutants are transported in a generally eastward direction so that older and more dilute mixtures occur to the east of the city. Photochemical ages determined from aircraft samples agree with those determined at a downwind surface site. The bias in photochemical age that occurs because fresh pollutants are added to an aged mixture has been quantified by using a particle trajectory model. A combination of trajectory results (actual age of the pollutants in an air mass) and photochemical age yields an estimate of the average OH concentration experienced by the air parcel. OH obtained in this way is somewhat lower, but has the same trends as OH concentrations calculated using a photochemical box model that is constrained with observed concentrations coincident with the VOC samples.

  7. Photochemical Assessment Monitoring Stations (PAMS)

    Data.gov (United States)

    U.S. Environmental Protection Agency — Photochemical Assessment Monitoring Stations (PAMS). This file provides information on the numbers and distribution (latitude/longitude) of air monitoring sites...

  8. The application of forest classification from Landsat data as a basis for natural hydrocarbon emission estimation and photochemical oxidant model simulations in southeastern Virginia

    Science.gov (United States)

    Salop, J.; Wakelyn, N. T.; Levy, G. F.; Middleton, W. M.; Gervin, J. C.

    1983-01-01

    The possible contribution by natural hydrocarbon emissions to the total ozone budget recorded in the Tidewater region of southeastern Virginia during the height of the summer period was examined. Natural sources investigated were limited to the primary HC emitters and most prevalent natural vegetation, the forests. Three types and their areal coverage were determined for Region VI of the Virginia State Air Pollution Control Board using remotely sensed data from Landsat, a NASA experimental earth resources satellite. Emission factors appropriate to the specific types (coniferous 0.24 x 10 to the 13th, mixed 0.63 x 10 to the 13th, deciduous 1.92 x 10 to the 13th, microgram/h), derived from contemporary procedures, were applied to produce an overall regional emission rate of 2.79 x 10 to the 13th microgram/h for natural non-methane hydrocarbons (NMHC). This rate was used with estimates of the anthropogenic NO(x) and NMHC loading, as input into a photochemical box model. Additional HC loading on the order of that estimated to be produced by the natural forest communities was required in order to reach certain measured summer peak ozone levels as the computer simulation was unable to account for the measured episodic levels on the basis of the anthropogenic inventory alone.

  9. Carbon monoxide may be an important molecule in migraine and other headaches

    DEFF Research Database (Denmark)

    Arngrim, Nanna; Schytz, Henrik W; Hauge, Mette K

    2014-01-01

    INTRODUCTION: Carbon monoxide was previously considered to just be a toxic gas. A wealth of recent information has, however, shown that it is also an important endogenously produced signalling molecule involved in multiple biological processes. Endogenously produced carbon monoxide may thus play...... an important role in nociceptive processing and in regulation of cerebral arterial tone. DISCUSSION: Carbon monoxide-induced headache shares many characteristics with migraine and other headaches. The mechanisms whereby carbon monoxide causes headache may include hypoxia, nitric oxide signalling and activation...

  10. Catalytic oxidation of carbon monoxide and propane on NiO-LaCoO3%NiO-LaCoO3催化剂的丙烷和CO氧化性能

    Institute of Scientific and Technical Information of China (English)

    章轩语; 陈忠; 周颖; 邢丰; 胡庚申; 罗孟飞

    2015-01-01

    A series of NiO-LaCoO3were synthesized by solid-phase reaction method. The effects of calcination temperature and the content of Ni in catalyst on the carbon monoxide and propane oxidation performance of the as-synthesized catalysts were investigated. These catalysts were characterized by X-ray diffraction (XRD),hydrogen temperature-programmed reduction (H2-TPR) and other techniques. The results indicate that lower calcination temperature is beneficial for better catalytic performance. Among all catalysts,10NiO-LaCoO3calcinated at 700℃ exhibited the best catalytic performance. The addition of Ni into the structure of LaCoO3can significantly enhance the carbon monoxide and propane oxidation activity,and the optimal NiO loading is 7.5%. It was also found that the catalytic performance of catalysts is highly associated with oxygen mobility in catalysts.%采用固相反应制备了NiO-LaCoO3催化剂,考察了焙烧温度以及Ni含量对催化剂的CO和丙烷氧化活性的影响.用X射线粉末衍射、H2-程序升温还原等技术对催化剂进行了表征.结果表明,在焙烧温度为700~1000℃时,焙烧温度越高,催化剂的丙烷和CO氧化性能越差,其中700℃焙烧后的10NiO-LaCoO3催化剂的效果最好.助剂Ni能有效提高LaCoO3催化剂的丙烷和CO氧化性能,其中Ni含量为7.5%的7.5NiO-LaCoO3催化剂氧化性能最佳.研究发现催化剂的CO和丙烷氧化活性与催化剂中氧活动性具有相关性.

  11. Solid-state charge-based device for control of catalytic carbon monoxide oxidation on platinum nanofilms using external bias and light.

    Science.gov (United States)

    Baker, L Robert; Hervier, Antoine; Kennedy, Griffin; Somorjai, Gabor A

    2012-05-09

    Using a Pt/Si catalytic nanodiode, we externally control the rate of CO oxidation on a Pt nanofilm. The catalytic reaction can be turned on and off by alternating between bias states of the device. Additionally, the reaction rate is sensitive to photocurrent induced by visible light. The effects of both bias and light show that negative charge on the Pt increases catalytic activity, while positive charge on the Pt decreases catalytic activity for CO oxidation.

  12. The effect of fuel composition on the formation of photochemical smog

    Energy Technology Data Exchange (ETDEWEB)

    Dutkiewicz, R.K. [Cape Town Univ. (South Africa). Energy Research Inst.

    1995-12-31

    The high level of solar radiation, moderate to high ambient temperatures and increasing vehicle density have resulted in an increasing number of incidents of photochemical smog in Cape Town. Whilst the situation has not reached levels reported from many cities around the world there is concern that photochemical smog may become a serious pollution problem. Work has started on a characterization of the photochemical smog and to determine what measures will be required to limit photochemical smog. The work has consisted of the monitoring of ambient levels of photochemical precursors such as hydrocarbons and oxides of nitrogen, and measurement of ozone. In addition to continuous monitoring by the Cape Town City Council some measurements have been made of PAN and other components of photochemical smog. In addition a study is being carried out of the composition of a brown haze which envelopes CaPe Town during spring and autumn under strong inversion episodes. In addition to ambient monitoring, work is being carried out on the effect of vehicle emissions and fuel evaporation on the formation of photochemical smog. This work involves the formation of photochemical smog in an indoor smog chamber in which exhaust emissions and volatile organic compounds are tested in terms of their photochemical smog tendency. This work is aimed at estimating the effect of increasing precursor levels on the potential photochemical smog situation in Cape Town

  13. Photochemical transformation of vanadium(5) acetylacetonate complexes

    Energy Technology Data Exchange (ETDEWEB)

    Kuchmij, S.Ya.; Turchaninov, A.M.; Kryukov, A.I. (AN Ukrainskoj SSR, Kiev. Inst. Fizicheskoj Khimii)

    1980-08-01

    Photochemical transformations of mixed vanadium (5) complex formed as a result of interaction between ethylorthovanadate and acetylacetone which includes in the first coordination sphere vanadyl oxygen, two enolate-ions and enthoxygroup are studied spectrophotometrically and using ESR method. During irradiation of ethanol solutions of the complex a successive reduction of central atom with formation of acetyl-acetonate complexes of vanadium (4) and (3) takes place. At that the solvent is oxidated. In CCl/sub 4/ solution under the effect of UV irradiation ethoxygroup is replaced by chlorine ion with the formation of new mixed vanadium (5) complex, sensible to visible and UV radiation.

  14. Hydroxylamine-induced oxidation of ferrous carbonylated truncated hemoglobins from Mycobacterium tuberculosis and Campylobacter jejuni is limited by carbon monoxide dissociation.

    Science.gov (United States)

    Ascenzi, Paolo; Ciaccio, Chiara; Gasperi, Tecla; Pesce, Alessandra; Caporaso, Lucia; Coletta, Massimo

    2017-08-01

    Hydroxylamine (HA) is an oxidant of ferrous globins and its action has been reported to be inhibited by CO, even though this mechanism has not been clarified. Here, kinetics of the HA-mediated oxidation of ferrous carbonylated Mycobacterium tuberculosis truncated hemoglobin N and O (Mt-trHbN(II)-CO and Mt-trHbO(II)-CO, respectively) and Campylobacter jejuni truncated hemoglobin P (Cj-trHbP(II)-CO), at pH 7.2 and 20.0 °C, are reported. Mixing Mt-trHbN(II)-CO, Mt-trHbO(II)-CO, and Cj-trHbP(II)-CO solution with the HA solution brings about absorption spectral changes reflecting the disappearance of the ferrous carbonylated derivatives with the concomitant formation of the ferric species. HA oxidizes irreversibly Mt-trHbN(II)-CO, Mt-trHbO(II)-CO, and Cj-trHbP(II)-CO with the 1:2 stoichiometry. The dissociation of CO turns out to be the rate-limiting step for the oxidation of Mt-trHbN(II)-CO, Mt-trHbO(II)-CO, and Cj-trHbP(II)-CO by HA. Values of the second-order rate constant for HA-mediated oxidation of Mt-trHbN(II)-CO, Mt-trHbO(II)-CO, and Cj-trHbP(II)-CO range between 8.8 × 10(4) and 8.6 × 10(7) M(-1) s(-1), reflecting different structural features of the heme distal pocket. This study (1) demonstrates that the inhibitory effect of CO is linked to the dissociation of this ligand, giving a functional basis to previous studies, (2) represents the first comparative investigation of the oxidation of ferrous carbonylated bacterial 2/2 globins belonging to the N, O, and P groups by HA, (3) casts light on the correlation between kinetics of HA-mediated oxidation and carbonylation of globins, and (4) focuses on structural determinants modulating the HA-induced oxidation process.

  15. Effect of preparation method on the surface characteristics and activity of the Pd/OMS-2 catalysts for the oxidation of carbon monoxide, toluene, and ethyl acetate

    Science.gov (United States)

    Liu, Lisha; Song, Yong; Fu, Zhidan; Ye, Qing; Cheng, Shuiyuan; Kang, Tianfang; Dai, Hongxing

    2017-02-01

    The cryptomelane-type manganese oxide octahedral molecular sieve (OMS-2)-supported Pd (0.5 wt% Pd/OMS-2-DP, 0.5 wt% Pd/OMS-2-PI, and 0.5 wt% Pd/OMS-2-EX) catalysts were prepared by the deposition-precipitation, pre-incorporation, and ion-exchanging strategies, respectively. It is shown that the preparation method exerted an important effect on the physicochemical property of the sample. Among the OMS-2-supported Pd catalysts, 0.5 wt% Pd/OMS-2-DP possessed the highest surface (Mn2+ + Mn3+)/Mn4+ atomic ratio and the highest surface Pd loading and acid sites. The 0.5 wt% Pd/OMS-2 catalysts outperformed the Pd-free counterpart, among which 0.5 wt% Pd/OMS-2-DP presented the best catalytic activity (T50% and T90% were 25 and 55 °C for CO oxidation, 240 and 285 °C for toluene oxidation, and 160 and 200 °C for ethyl acetate oxidation, respectively). We believe that the high Pd surface loading, high surface atomic ratio of (Mn2+ + Mn3+)/Mn4+, and good low-temperature reducibility, good oxygen mobility, and high acidity were responsible for the excellent performance of the 0.5 wt% Pd/OMS-2-DP catalyst.

  16. Carbon Monoxide (CO) Poisoning Prevention

    Science.gov (United States)

    ... Recommend on Facebook Tweet Share Compartir When power outages occur after severe weather (such as winter storms, hurricanes or tornadoes), using alternative sources of power can cause carbon monoxide (CO) to build up in a ...

  17. Carbon Monoxide Mixing Ratio System

    Data.gov (United States)

    Oak Ridge National Laboratory — The Southern Great Plains (SGP) Carbon Monoxide (CO) system provides high-precision atmospheric concentration measurements of CO mixing ratio (ppbv dry air) every 10...

  18. Variation characteristics of carbon monoxide and ozone over the course of the 2014 Chinese National Arctic Research Expedition

    Institute of Scientific and Technical Information of China (English)

    LI Bokun; BIAN Lingen; ZHENG Xiangdong; DING Minghu; XIE Zhouqing

    2015-01-01

    The concentrations of carbon monoxide and ozone in the marine boundary layer were measured during the 6th Chinese National Arctic Research Expedition (from July to September, 2014). Carbon monoxide concentration ranged between 47.00 and 528.52 ppbv with an average of 103.59 ± 40.37 ppbv. A slight decrease with increasing latitude was observed, except for the extremely high values over the East China Sea which may be attributed to anthropogenic emissions. Ozone concentration ranged between 3.27 and 77.82 ppbv with an average of 29.46±10.48 ppbv. Ozone concentration decreased sharply with increasing latitude outside the Arctic Ocean (during both the northward and the southward course), while no significant variation was observed over the Arctic Ocean. The positive correlation between carbon monoxide and ozone in most sections suggests that the ozone in the marine boundary layer mainly originated from photochemical reactions involving carbon monoxide.

  19. Gold stabilized aqueous sols immobilized on mesoporous CeO2-Al2O3 as catalysts for the preferential oxidation of carbon monoxide.

    Science.gov (United States)

    Storaro, Loretta; Lenarda, Maurizio; Moretti, Elisa; Talon, Aldo; Porta, Francesca; Moltrasio, Bernardo; Canton, Patrizia

    2010-10-15

    Nanostructured Au/Al(2)O(3)-CeO(2) catalysts with a low content of precious metal (0.9% wt.) were prepared immobilizing two different stabilized Au sols on a high surface area Al(2)O(3)-CeO(2) mixed oxide with a uniform pore size distribution, synthesized by a one-pot methodology. The samples were characterized by elemental analysis, N(2) physisorption, XRPD, TEM and (27)Al-MAS NMR techniques. The catalytic activity of the two samples in the preferential oxidation of CO in excess of H(2) (CO-PROX) was comparatively evaluated in the 35-110 degrees C temperature range. The Au-THPS/AlCe20 sample, prepared immobilizing a sol obtained reducing an aqueous solution of gold tetrachloroaurate salt with bis[tetrakis(hydroxymethyl)phosphonium sulfate], resulted very active and selective at low temperatures and its catalytic activity was correlated with the structural characteristics of the metal particles and of the ordered mesoporous support. Copyright 2010 Elsevier Inc. All rights reserved.

  20. Fabrication and anti-fouling properties of photochemically and thermally immobilized poly(ethylene oxide) and low molecular weight poly(ethylene glycol) thin films.

    Science.gov (United States)

    Wang, Hui; Ren, Jin; Hlaing, Aye; Yan, Mingdi

    2011-02-01

    Poly(ethylene oxide) (PEO) and low molecular weight poly(ethylene glycol) (PEG) were covalently immobilized on silicon wafers and gold films by way of the CH insertion reaction of perfluorophenyl azides (PFPAs) by either photolysis or thermolysis. The immobilization does not require chemical derivatization of PEO or PEG, and polymers of different molecular weights were successfully attached to the substrate to give uniform films. Microarrays were also generated by printing polymer solutions on PFPA-functionalized wafer or Au slides followed by light activation. For low molecular weight PEG, the immobilization was highly dependent on the quality of the film deposited on the substrate. While the spin-coated and printed PEG showed poor immobilization efficiency, thermal treatment of the PEG melt on PFPA-functionalized surfaces resulted in excellent film quality, giving, for example, a grafting density of 9.2×10(-4)Å(-2) and an average distance between grafted chains of 33Å for PEG 20,000. The anti-fouling property of the films was evaluated by fluorescence microscopy and surface plasmon resonance imaging (SPRi). Low protein adsorption was observed on thermally-immobilized PEG whereas the photoimmobilized PEG showed increased protein adsorption. In addition, protein arrays were created using polystyrene (PS) and PEG based on the differential protein adsorption of the two polymers.

  1. Photochemical oxidant injury and bark beetle coleoptera scolytidae infestation of ponderosa pine. I. Incidence of bark beetle infestation in injured trees

    Energy Technology Data Exchange (ETDEWEB)

    Stark, R.W.; Miller, P.R.; Cobb, F.W. Jr.; Wood, D.L.; Parmeter, J.R. Jr.

    1968-05-01

    A total of 107 beetle-killed and 963 nearest-neighbor ponderosa pines were examined to determine the association between severity of atmospheric pollution injury and infestation by bark beetles. Trees exhibiting advanced symptoms of pollution injury were most frequently infested by the western pine beetle, Dendroctonus brevicomis, and the mountain pine beetle, D. ponderosae. The degree of injury and incidence of bark beetle infestation were not related to total height, diameter, length of live and dead crown or crown class. As severity of oxidant injury increased, live crown ratio decreased and incidence of bark beetle infestation increased. One hundred noninfested trees in each of three disease categories, advanced, intermediate, and healthy, were examined for evidence of prior beetle attacks. Thirty-six percent of the advanced-diseased trees versus only 5% of the healthy trees were attacked. Thus, the beetles may discriminate between healthy and diseased trees at a distance, upon contact with the host, or both. These studies indicate strongly that atmospheric pollution injury predisposes ponderosa pine to bark beetle infestations. 3 references, 7 tables.

  2. Photochemical Synthesis of Au@Pd Core-Shell Nanoparticles for Methanol Oxidation Reaction: the Promotional Effect of the Au Core

    Directory of Open Access Journals (Sweden)

    Dong Yingnan

    2016-01-01

    Full Text Available A novel method for synthesizing Au@Pd core-shell nanoparticles was proposed based on photochemistry. By irradiating the mixture of Au (III and Pd (II ions using ultraviolet light, the Au@Pd core-shell nanoparticles were prepared. The size of the nanoparticles and the thickness of the Pd shell could be efficiently adjusted by changing the molar ratio of Au (III to Pd (II ion. In this way, nanoparticles with diameter in the range of 5.6~4.6 nm were obtained. The core-shell structure of the synthesized nanoparticles was showed by the characterization using UV-Vis, TEM/HR-TEM and XPS. The paper investigated the electrocatalysis performance of Au@Pd nanoparticles in the methanol catalytic oxidation reaction, as well as the electron donating effect of Au core to Pd shell and the promotion of this effect on the catalytic activity of Pd shell. The experimental results provided reference for the development of non-platinum catalysts of low-temperature fuel cell anode.

  3. Research opportunities in photochemical sciences

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1996-07-01

    The workshop entitled {open_quotes}Research Opportunities in Photochemical Sciences{close_quotes} was initiated by the U.S. Department of Energy (DOE), Office of Energy Research (ER), Office of Basic Energy Sciences (BES), Division of Chemical Sciences. The National Renewable Energy Laboratory (NREL) in Golden, Colorado was requested by ER to host the workshop. It was held February 5-8, 1996 at the Estes Park Conference Center, Estes Park, CO, and attended by about 115 leading scientists and engineers from the U.S., Japan, and Europe; program managers for the DOE ER and Energy Efficiency and Renewable Energy (EERE) programs also attended. The purpose of the workshop was to bridge the communication gap between the practioneers and supporters of basic research in photochemical science and the practioneers and supporters of applied research and development in technologies related to photochemical science. For the purposes of the workshop the definition of the term {open_quotes}photochemical science{close_quotes} was broadened to include homogeneous photochemistry, heterogeneous photochemistry, photoelectrochemistry, photocatalysis, photobiology (for example, the light-driven processes of biological photosynthesis and proton pumping), artificial photosynthesis, solid state photochemistry, and solar photochemistry. The technologies under development through DOE support that are most closely related to photochemical science, as defined above, are the renewable energy technologies of photovoltaics, biofuels, hydrogen energy, carbon dioxide reduction and utilization, and photocatalysis for environmental cleanup of water and air. Individual papers were processed separately for the United states Department of Energy databases.

  4. Engineering photochemical smog through convection towers

    Energy Technology Data Exchange (ETDEWEB)

    Elliott, S.; Prueitt, M.L.; Bossert, J.E.; Mroz, E.J.; Krakowski, R.A.; Miller, R.L. [Los Alamos National Lab., NM (United States); Jacobson, M.Z.; Turco, R.P. [Los Alamos National Lab., NM (United States)]|[Univ. of California, Los Angeles, CA (United States). Atmospheric Sciences Dept.

    1995-02-01

    Reverse convection towers have attracted attention as a medium for cleansing modern cities. Evaporation of an aqueous mist injected at the tower opening could generate electrical power by creating descent, and simultaneously scavenge unsightly and unhealthful particulates. The study offered here assesses the influence to tower water droplets on the photochemical component of Los Angeles type smog. The primary radical chain initiator OH is likely removed into aqueous phases well within the residence time of air in the tower, and then reacts away rapidly. Organics do not dissolve, but nighttime hydrolysis of N{sub 2}O{sub 5} depletes the nitrogen oxides. A lack of HOx would slow hydrocarbon oxidation and so also ozone production. Lowering of NOx would also alter ozone production rates, but the direction is uncertain. SO{sub 2} is available in sufficient quantities in some urban areas to react with stable oxidants, and if seawater were the source of the mist, the high pH would lead to fast sulfur oxidation kinetics. With an accommodation coefficient of 10{sup {minus}3}, however, ozone may not enter the aqueous phase efficiently. Even if ozone is destroyed or its production suppressed, photochemical recovery times are on the order of hours, so that tower processing must be centered on a narrow midday time window. The cost of building the number of structures necessary for this brief turnover could be prohibitive. The increase in humidity accompanying mist evaporation could be controlled with condensers, but might otherwise counteract visibility enhancements by recreating aqueous aerosols. Quantification of the divergent forcings convection towers must exert upon the cityscape would call for coupled three dimensional modeling of transport, microphysics, and photochemistry. 112 refs.

  5. Degradation of dibutyl phthalate (DBP) by UV-254 nm/H2O2 photochemical oxidation: kinetics and influence of various process parameters.

    Science.gov (United States)

    Wang, Dong; Duan, Xiaodi; He, Xuexiang; Dionysiou, Dionysios D

    2016-12-01

    Degradation of dibuytl phthalate (DBP), a plasticizer and also a widely distributed endocrine disruptor, by UV-254 nm/H2O2 advanced oxidation process (AOP) was investigated in this study. A significant DBP removal of 77.1 % at an initial concentration of 1.0 μM was achieved at UV fluence of 160 mJ/cm(2), initial H2O2 dosage of 1.0 mM, and pH of 7.6 ± 0.1. The DBP degradation exhibited a pseudo-first-order reaction kinetic pattern, with the rate constants linearly increasing with increasing H2O2 dosage while decreasing with increasing initial DBP concentration and pH value in a specific range. DBP destruction was significantly inhibited in the presence of alkalinity and natural organic matter (NOM), two known factors that should be taken a serious consideration of in the research and design of UV/H2O2-based AOPs. Presence of common inorganic anions (i.e., Cl(-), SO4(2-), and NO3(-)) and metal cations (i.e., Fe(3+) and Zn(2+)) had a slight impact on the degradation of DBP, although Cu(2+) could improve the degradation efficiency even at a concentration as low as 0.01 mg/L, suggesting a strong potential of applying UV/H2O2 for the removal of DBP with an environmental relevant level of copper.

  6. 光化学烟雾研究综述%The Summary of Research on Photochemical Smog

    Institute of Scientific and Technical Information of China (English)

    戴华茂

    2009-01-01

    With the sustained development of our country, and the growth of fuel consumption year by year, carbon monoxide, nitrogen oxides and hydrocarbons such as contamination emissions are also growing rapidly. These are the raw material for the formation of photochemical smog. Once the formation of photochernical smog, affection is a wide range. And its harmfulness has caused enormous threat for city environment, human health, ecological balance. Therefore carry out the energy-saving and emission reduction policies, and control the emissions of air pollutants must be done. The paper analyzed the formation, conditions and mechanism of photochemical smog. And set forth the harm and the prevention and control measures,%伴随我国经济的持续商速发展,燃料的消耗最逐年增长,大气中一氧化碳、氮氧化物及碳氢化物等污染物的排放量也迅速增长,这些都是形成光化学烟雾的原料.光化学烟雾一旦形成,影响范围广,其危害性已对城市环境、人体健康、生态环境平衡造成巨大危胁.因此贯彻节能减排政策,控制大气污染物排放量势在必行.文章分析了光化学烟雾形成的条件及机理,阐述了造成的危害和防治措施.

  7. Electrocatalytic studies of osmium-ruthenium carbonyl cluster compounds for their application as methanol-tolerant cathodes for oxygen reduction reaction and carbon monoxide-tolerant anodes for hydrogen oxidation reaction

    Energy Technology Data Exchange (ETDEWEB)

    Borja-Arco, E.; Uribe-Godinez, J.; Castellanos, R.H. [Centro de Investigacion y Desarrollo Tecnologico en Electroquimica, Escobedo (Mexico); Altamirano-Gutierrez, A.; Jimenez-Sandoval, O. [Centro de Investigacion y de Estudios Avanzados del Inst. Politecnico Nacional, Querataro (Mexico)

    2006-07-01

    This paper provided details of an electrokinetic study of novel electrocatalytic materials capable of performing both the oxygen reduction reaction (ORR) and the hydrogen oxidation reaction (HOR). Osmium-ruthenium carbonyl cluster compounds (Os{sub x}Ru{sub 3}(CO){sub n}) were synthesized by chemical condensation in non-polar organic solvents at different boiling points and refluxing temperatures. Three different non-polar organic solvents were used: (1) n-nonane; o-xylene; and 1,2-dichlorobenzene. The electrocatalysts were characterized by Fourier Transform Infra-red (FTIR) spectroscopy, scanning electron microscopy (SEM) and X-ray diffraction (XRD). A rotating disk electrode technique was used to analyze the materials. Results of the analysis showed that the materials performed ORR in both the presence and absence of carbon monoxide (CO), and that electrocatalysts were not poisoned by the presence of CO. Cyclic voltamperometry for the disk electrodes showed that the electrochemical behaviour of the compounds in the acid electrolyte was similar in the presence or absence of methanol. The Tafel slope, exchange current density and the transfer coefficient were also investigated. The electrokinetic parameters for the ORR indicated that the materials with the highest electrocatalytic activity were synthesized in 1,2-dichlorobenzene. Electrocatalytic activity during HOR were prepared in n-nonane. It was concluded that the new materials are good candidates for use as both a cathode and an anode in proton exchange membrane fuel cells (PEMFCs) and direct methanol fuel cells (DMFCs). 7 refs., 2 tabs., 7 figs.

  8. Method of removing nitrogen monoxide from a nitrogen monoxide-containing gas using a water-soluble iron ion-dithiocarbamate, xanthate or thioxanthate

    Science.gov (United States)

    Liu, D. Kwok-Keung; Chang, Shih-Ger

    1987-08-25

    The present invention relates to a method of removing of nitrogen monoxide from a nitrogen monoxide-containing gas which method comprises contacting a nitrogen oxide-containing gas with an aqueous solution of water soluble organic compound-iron ion chelate complex. The NO absorption efficiency of ferrous urea-dithiocarbamate and ferrous diethanolamine-xanthate as a function of time, oxygen content and solution ph is presented. 3 figs., 1 tab.

  9. Photochemical processing of aqueous atmospheric brown carbon

    Directory of Open Access Journals (Sweden)

    R. Zhao

    2015-01-01

    Full Text Available Atmospheric Brown Carbon (BrC is a collective term for light absorbing organic compounds in the atmosphere. While the identification of BrC and its formation mechanisms is currently a central effort in the community, little is known about the atmospheric removal processes of aerosol BrC. As a result, we report a series of laboratory studies of photochemical processing of BrC in the aqueous phase, by direct photolysis and OH oxidation. Solutions of ammonium sulfate mixed with glyoxal (GLYAS or methylglyoxal (MGAS are used as surrogates for a class of secondary BrC mediated by imine intermediates. Three nitrophenol species, namely 4-nitrophenol, 5-nitroguaiacol and 4-nitrocatechol, were investigated as a class of water soluble BrC originating from biomass burning. Photochemical processing induced significant changes in the absorptive properties of BrC. The imine-mediated BrC solutions exhibited rapid photo-bleaching with both direct photolysis and OH oxidation, with atmospheric half-lives of minutes to a few hours. The nitrophenol species exhibited photo-enhancement in the visible range during direct photolysis and the onset of OH oxidation, but rapid photo-bleaching was induced by further OH exposure on an atmospheric timescale of an hour or less. To illustrate atmospheric relevance of this work, we also performed direct photolysis experiments on water soluble organic carbon extracted from biofuel combustion samples and observed rapid changes in optical properties of these samples as well. Overall, these experiments indicate that atmospheric models need to incorporate representations of atmospheric processing of BrC species to accurately model their radiative impacts.

  10. Photochemical processing of aqueous atmospheric brown carbon

    Directory of Open Access Journals (Sweden)

    R. Zhao

    2015-06-01

    Full Text Available Atmospheric brown carbon (BrC is a collective term for light absorbing organic compounds in the atmosphere. While the identification of BrC and its formation mechanisms is currently a central effort in the community, little is known about the atmospheric removal processes of aerosol BrC. As a result, we report on a series of laboratory studies of photochemical processing of BrC in the aqueous phase, by direct photolysis and OH oxidation. Solutions of ammonium sulfate mixed with glyoxal (GLYAS or methylglyoxal (MGAS are used as surrogates for a class of secondary BrC mediated by imine intermediates. Three nitrophenol species, namely 4-nitrophenol, 5-nitroguaiacol and 4-nitrocatechol, were investigated as a class of water-soluble BrC originating from biomass burning. Photochemical processing induced significant changes in the absorptive properties of BrC. The imine-mediated BrC solutions exhibited rapid photo-bleaching with both direct photolysis and OH oxidation, with atmospheric half-lives of minutes to a few hours. The nitrophenol species exhibited photo-enhancement in the visible range during direct photolysis and the onset of OH oxidation, but rapid photo-bleaching was induced by further OH exposure on an atmospheric timescale of an hour or less. To illustrate the atmospheric relevance of this work, we also performed direct photolysis experiments on water-soluble organic carbon extracted from biofuel combustion samples and observed rapid changes in the optical properties of these samples as well. Overall, these experiments indicate that atmospheric models need to incorporate representations of atmospheric processing of BrC species to accurately model their radiative impacts.

  11. Photochemical processing of aqueous atmospheric brown carbon

    Science.gov (United States)

    Zhao, R.; Lee, A. K. Y.; Huang, L.; Li, X.; Yang, F.; Abbatt, J. P. D.

    2015-06-01

    Atmospheric brown carbon (BrC) is a collective term for light absorbing organic compounds in the atmosphere. While the identification of BrC and its formation mechanisms is currently a central effort in the community, little is known about the atmospheric removal processes of aerosol BrC. As a result, we report on a series of laboratory studies of photochemical processing of BrC in the aqueous phase, by direct photolysis and OH oxidation. Solutions of ammonium sulfate mixed with glyoxal (GLYAS) or methylglyoxal (MGAS) are used as surrogates for a class of secondary BrC mediated by imine intermediates. Three nitrophenol species, namely 4-nitrophenol, 5-nitroguaiacol and 4-nitrocatechol, were investigated as a class of water-soluble BrC originating from biomass burning. Photochemical processing induced significant changes in the absorptive properties of BrC. The imine-mediated BrC solutions exhibited rapid photo-bleaching with both direct photolysis and OH oxidation, with atmospheric half-lives of minutes to a few hours. The nitrophenol species exhibited photo-enhancement in the visible range during direct photolysis and the onset of OH oxidation, but rapid photo-bleaching was induced by further OH exposure on an atmospheric timescale of an hour or less. To illustrate the atmospheric relevance of this work, we also performed direct photolysis experiments on water-soluble organic carbon extracted from biofuel combustion samples and observed rapid changes in the optical properties of these samples as well. Overall, these experiments indicate that atmospheric models need to incorporate representations of atmospheric processing of BrC species to accurately model their radiative impacts.

  12. Impact of Mg2+ ion incorporation on the phase development of ZrO2-type solid solutions and their application in the catalytic oxidation of carbon monoxide

    Science.gov (United States)

    Nemec, Vinko; Kaper, Helena; Pétaud, Guillaume; Ivanda, Mile; Štefanić, Goran

    2017-07-01

    The precursors of ZrO2-MgO system covering the whole concentration range were prepared by co-precipitation of the corresponding nitrate salts. The obtained precursors were calcined in air at different temperatures up to 1000 °C and analyzed at room temperature using X-ray powder diffraction (XRD), Raman spectroscopy, field emission scanning electron microscopy (FESM) and energy dispersive X-ray spectrometry (EDS). Maximum solubility of Mg2+ ions (∼32 mol%) was obtained in the amorphous precursor. After crystallization at 600 °C the solid solubility of Mg2+ ions decreases to ∼26 mol% of which ∼22 mol% was incorporated inside ZrO2-type lattice while the remaining part of Mg2+ ions was adsorbed on the surface of the particles. Further thermal treatment decreases solubility of Mg2+ ions to 18 mol% (800 °C) and finally to 9 mol% (1000 °C). On the other side of the concentration range, the solubility of Zr4+ ions in MgO lattice was 10 mol%) polymorphs. A precise determination of unit-cell parameters shows that the increase in the Mg2+ content causes a decrease in the parameter c of tetragonal ZrO2 lattice, which in a solid solution with a Mg2+ content ≥10 mol% becomes very close to the lattice parameter a (approaching cubic lattice). The results of FE-SEM analysis show that the addition of Mg2+ ions promotes sintering of samples. The influence of thermal treatment on the crystallization of the amorphous precursors to ZrO2-type lattice was examined by differential thermal analysis and thermogravimetric measurement. The obtained results show that the crystallization temperature increases with increasing Mg content, from 445 °C (0 mol% MgO) to 625 °C (∼50 mol% MgO). The ZrO2 doped with 3 mol% MgO was used as catalyst support for platinum nanoparticles and compared to commercially available 3% yttria-doped stabilized zirconia (3YSZ). The catalysts were used for catalytic CO oxidation and show slightly better performance of the ZrO2-MgO system, which

  13. (Carbon monoxide metabolism by photosynthetic bacteria)

    Energy Technology Data Exchange (ETDEWEB)

    1989-01-01

    Research continued on the metabolism of carbon monoxide by Rhodospirillum rubrum. This report discusses progress on the activity, induction, inhibition, and spectroscopic analysis of the enzyme Carbon Monoxide Dehydrogenase. (CBS)

  14. Carbon Monoxide Silicate Reduction System Project

    Data.gov (United States)

    National Aeronautics and Space Administration — The Carbon Monoxide Silicate Reduction System (COSRS) is an innovative method that for the first time uses the strong reductant carbon monoxide to both reduce iron...

  15. Seasonal photochemical transformations of nitrogen species in a forest stream and lake.

    Directory of Open Access Journals (Sweden)

    Petr Porcal

    Full Text Available The photochemical release of inorganic nitrogen from dissolved organic matter is an important source of bio-available nitrogen (N in N-limited aquatic ecosystems. We conducted photochemical experiments and used mathematical models based on pseudo-first-order reaction kinetics to quantify the photochemical transformations of individual N species and their seasonal effects on N cycling in a mountain forest stream and lake (Plešné Lake, Czech Republic. Results from laboratory experiments on photochemical changes in N speciation were compared to measured lake N budgets. Concentrations of organic nitrogen (Norg; 40-58 µmol L-1 decreased from 3 to 26% during 48-hour laboratory irradiation (an equivalent of 4-5 days of natural solar insolation due to photochemical mineralization to ammonium (NH4+ and other N forms (Nx; possibly N oxides and N2. In addition to Norg mineralization, Nx also originated from photochemical nitrate (NO3- reduction. Laboratory exposure of a first-order forest stream water samples showed a high amount of seasonality, with the maximum rates of Norg mineralization and NH4+ production in winter and spring, and the maximum NO3- reduction occurring in summer. These photochemical changes could have an ecologically significant effect on NH4+ concentrations in streams (doubling their terrestrial fluxes from soils and on concentrations of dissolved Norg in the lake. In contrast, photochemical reactions reduced NO3- fluxes by a negligible (<1% amount and had a negligible effect on the aquatic cycle of this N form.

  16. Carbon monoxide formation in tomatoes

    Energy Technology Data Exchange (ETDEWEB)

    Gladon, R.J.; Staby, G.L.

    1979-01-01

    Carbon monoxide (CO) is not emanated to any large extent from tomato fruits (Lycopersicon esculentum, Mill. cvs. Rutgers and Ohio MR-13), but is retained within the internal atmosphere. CO is found during all stages of fruit development, but no set pattern of CO concentration is evident.

  17. MOPITT Carbon Monoxide Over India

    Science.gov (United States)

    2002-01-01

    MOPITT observed high levels of carbon monoxide (red and yellow pixels) over the Indian sub-continent during March. These values are associated with industrial activity in the region just south of the Himalayan Mountains. Notice that to the north, the Himalayas are characterized by low values (blue pixels).

  18. The Protective Role of Carbon Monoxide (CO Produced by Heme Oxygenases and Derived from the CO-Releasing Molecule CORM-2 in the Pathogenesis of Stress-Induced Gastric Lesions: Evidence for Non-Involvement of Nitric Oxide (NO

    Directory of Open Access Journals (Sweden)

    Katarzyna Magierowska

    2016-03-01

    Full Text Available Carbon monoxide (CO produced by heme oxygenase (HO-1 and HO-2 or released from the CO-donor, tricarbonyldichlororuthenium (II dimer (CORM-2 causes vasodilation, with unknown efficacy against stress-induced gastric lesions. We studied whether pretreatment with CORM-2 (0.1–10 mg/kg oral gavage (i.g., RuCl3 (1 mg/kg i.g., zinc protoporphyrin IX (ZnPP (10 mg/kg intraperitoneally (i.p., hemin (1–10 mg/kg i.g. and CORM-2 (1 mg/kg i.g. combined with NG-nitro-l-arginine (l-NNA, 20 mg/kg i.p., 1H-[1,2,4]oxadiazolo[4,3-a]quinoxalin-1-one (ODQ, 10 mg/kg i.p., indomethacin (5 mg/kg i.p., SC-560 (5 mg/kg i.g., and celecoxib (10 mg/kg i.g. affects gastric lesions following 3.5 h of water immersion and restraint stress (WRS. Gastric blood flow (GBF, the number of gastric lesions and gastric CO and nitric oxide (NO contents, blood carboxyhemoglobin (COHb level and the gastric expression of HO-1, HO-2, hypoxia inducible factor 1α (HIF-1α, tumor necrosis factor α (TNF-α, cyclooxygenase (COX-2 and inducible NO synthase (iNOS were determined. CORM-2 (1 mg/kg i.g. and hemin (10 mg/kg i.g. significantly decreased WRS lesions while increasing GBF, however, RuCl3 was ineffective. The impact of CORM-2 was reversed by ZnPP, ODQ, indomethacin, SC-560 and celecoxib, but not by l-NNA. CORM-2 decreased NO and increased HO-1 expression and CO and COHb content, downregulated HIF-1α, as well as WRS-elevated COX-2 and iNOS mRNAs. Gastroprotection by CORM-2 and HO depends upon CO’s hyperemic and anti-inflammatory properties, but is independent of NO.

  19. Masimo SET(R)Rad-57碳氧血氧测量仪在急性一氧化碳中毒急救中的应用%Clinical Application of Emergency Treatment in Patients with Carbon Monoxide Poisoning by Masimo SET (R) Rad-57 Carbonic Oxide Poisoning Monitor

    Institute of Scientific and Technical Information of China (English)

    吴耿茂; 林凯胜; 杨小旭; 刘育春; 黄国梁

    2015-01-01

    目的:探讨Masimo SET(R)Rad-57碳氧血氧测量仪在急性一氧化碳中毒患者早期诊断中的价值。方法:将2013年11月-2014年4月收治的急性一氧化碳中毒患者35例按照临床症状和体征分为轻、中、重度一氧化碳中毒,并与Masimo SET(R)Rad-57碳氧血氧测量仪测得的碳氧血红蛋白饱和度进行比较。结果:Masimo SET(R) Rad-57碳氧血氧测量仪测得的碳氧血红蛋白饱和度与一氧化碳中毒的病情相符,且轻、中、重度组间均有显著性差异(P均<0.01)。结论:急诊科应用Masimo SET(R)Rad-57碳氧血氧测量仪对一氧化碳中毒患者有早期诊断价值。%Objective:To investigate the early diagnosis value of patients with carbon monoxide poisoning by Masimo:SET (R)Rad-57 carbonic oxide poisoning monitor. Methods:35 patients with carbonic oxide poisoning were divided into light severity , medium severity and heavy according to the clinical symptoms and signs from Nov 2013 to Apr 2014, and the severities were compared with the saturation of carbonic oxide detected by Masimo SET(R)Rad-57 carbonic oxide poisoning monitor. Results:The saturations of carbonic oxide detected by Masimo SET (R) Rad-57 carbonic oxide poisoning monitor corresponded with the severities of the carbon monoxide poisoning. There were significant differences among the light, moderate and severe groups, all P<0.01. Conclusion:There is early diagnostic value for patients with carbon monoxide poisoning using Masimo SET (R)Rad-57 carbonic oxide poisoning monitor in department of emergency.

  20. Supramolecular Photochemistry Controlling Photochemical Processes

    CERN Document Server

    Ramamurthy, V

    2011-01-01

    This is the most updated, comprehensive collection of monographs on all aspects of photochemistry and photophysics related to natural and synthetic, inorganic, organic, and biological supramolecular systems. Supramolecular Photochemistry: Controlling Photochemical Processes addresses reactions in crystals, organized assemblies, monolayers, zeolites, clays, silica, micelles, polymers, dendrimers, organic hosts, supramolecular structures, organic glass, proteins and DNA, and applications of photosystems in confined media. This landmark publication describes the past, present, and future of this

  1. Photochemical pollution indicators; Les indicateurs de la pollution photochimique. La mesure des composes azotes

    Energy Technology Data Exchange (ETDEWEB)

    Perros, P.E.; Marion, T. [Paris-7 Univ., 75 (France). Laboratoire Interuniversitaire des Systemes Atmospheriques

    1998-11-01

    The number of photochemical pollution is generally based on the observation of ozone and nitrogen oxides concentration levels. So, the measurement of photochemical pollution indicators becomes essential to better understand the involved phenomena, and at the end to enable its reduction control and strategy. In this paper, we focus on the measurements of nitrogen compounds (NO{sub x} PAN, HNO{sub 3}). (authors) 24 refs.

  2. Photochemical reactions of neptunium in nitric acid solution containing photocatalyst

    Energy Technology Data Exchange (ETDEWEB)

    Fukasawa, Tetsuo; Kawamura, Fumio (Hitachi Ltd., Ibaraki (Japan). Energy Research Lab.)

    1991-01-01

    Photochemical oxidation and reduction behaviors of neptunium were preliminarily investigated in 3 mol/l nitric acid solution. Nitric acid of 3 mol/l simulated the high level waste solution from a spent fuel reprocessing process. Concentrations of Np(V), Np(VI) and nitrous acid were determined with a photospectrometer, and solution potential with an electrode. Without additives, Np(VI) was reduced to Np(V) by nitrous acid which was photolytically generated from nitric acid. With a scavenger for nitrous acid, Np(V) was oxidized to extractable Np(VI) by a photolytically generated oxidizing reagent which were predicted by the solution potential measurement. The reduction rate was higher than the oxidation rate because of the larger quantity and higher reactivity of nitrous acid than an oxidizing reagent. Photocatalyst was proved to be effective for the oxidation of Np(V) to Np(VI). (author).

  3. FIGAERO ToF CIMS measurements of chlorine photochemical activation by nitryl chloride chemistry at a semi-rural site in Beijing

    Science.gov (United States)

    Le Breton, Michael; Hallquist, Åsa M.; Kant Pathak, Ravi; Simpson, David; Wang, Yujue; Zheng, Jing; Yang, Yudong; Shang, Dongjie; Wang, Haichao; Lu, Keding; Guo, Song; Hu, Min; Hallquist, Mattias

    2017-04-01

    Severe pollution events across China pose a major threat to air quality and climate through the direct emission of pollutants, but also via the production of photochemically induced secondary pollutants. Nitryl chloride (ClNO2), produced from heterogeneous reactions of dinitrogen pentoxide (N2O5) and aerosols containing chloride, is photolysed rapidly in sunlight and activates chlorine. Subsequent daytime oxidation via the chlorine atom can proceed orders of magnitude faster than that of the hydroxyl radical and therefore significantly perturb radical budgets and concentrations of ozone and secondary pollutants. Knowledge of the formation pathways, abundance and fate of these secondary pollutants, which can depend on ClNO2 abundance, is not fully understood but is necessary to support abatement strategies which will efficiently account for both primary and secondary pollutants. A Time of Flight Chemical Ionisation Mass Spectrometer (ToF CIMS) utilising the Filter Inlet for Gases and AEROsols (FIGAERO) was deployed in Changping, Beijing, during June and July, 2016 as part of an intercollaborative project to assess the photochemical smog in China. Concentrations of ClNO2 regularly exceeded 500 ppt throughout the campaign and reached a maximum concentration of 2.8 ppb, whereas relatively low N2O5 concentrations were observed, indicating a rapid heterogeneous production of ClNO2. Correlation of particulate chloride and carbon monoxide during the campaign suggests an anthropogenic chlorine source, also supported by high daytime Cl2 concentrations. Observations of ClNO2 desorptions using the FIGAERO suggest a possible unaccounted particulate reservoir of active chlorine in highly polluted regions. The persistence of ClNO2 several hours passed sunrise significantly increases the atomic chlorine production rate throughout the day further perturbing standard daytime oxidation processes. Simultaneous ToF CIMS measurements of Cl2, ClNO2, HCl, HOCl, OClO and ClONO2 were

  4. Characterizing the unique photochemical environment in China

    Science.gov (United States)

    Liu, Z.; Wang, Y.; Gu, D.; Zhao, C.; Huey, L. G.; Stickel, R.; Liao, J.

    2010-12-01

    Recent observational evidence suggests that the atmospheric chemical system over China could be more complex than expected, possibly as a result of the rapid increasing anthropogenic emissions. During the CAREBeijing-2007 Experiment in August of 2007, up to 14 ppbv of peroxyacetyl nitrate (PAN, CH3C(O)OONO2) and 4.5 ppbv of glyoxal (CHOCHO) were observed, among the highest levels observed in the world in recent years. Elevated nitrous acid (HNO2) (~1.0 ppbv on average) was also observed in the early afternoon despite of the moderate amount of its precursors, i.e. nitrogen oxides (NOx=NO + NO2). We employ a 1-D photochemical model (REAM) to analyze the observations. The results indicate that reactive aromatics are the dominating source of PAN (55%-75%) and glyoxal (90%), and methylglyoxal is the major precursor of peroxy acetyl radical (50%). Downward transport from boundary layer is found to contribute ~50% of the PAN observed at surface. Photolysis of HNO2 is by far the largest primary OH source (more than 50%) throughout the daytime, and yet the fast formation rate of HNO2 inferred from the observations could not be explained by current known mechanisms. Detailed photochemical analysis is conducted to understand the controlling factors for O3 formation. O3 formation chemistry is strongly affected by aromatics and HNO2. By providing a large primary OH source, HNO2 leads to ~25% enhancement of the average O3 production rate, and aromatics contribute ~40% by serving as a major source of RO2 and HO2 radicals. Due to the large abundance of reactive hydrocarbons, O3 formation is generally NOx limited, although the sensitivity is low that a 50% reduction of NOx could only result in less than 25% reduction of the O3 production rate. Future research targeting HNO2 formation mechanism and emission sources of aromatics is necessary for better understanding the unique photochemical environment in China under significant anthropogenic impacts and the regional pollution

  5. Carbon monoxide kinetics following simulated cigarette smoking

    Energy Technology Data Exchange (ETDEWEB)

    Karnik, A.S. (Wayne State Univ., Detroit, MI); Coin, E.J.

    1980-05-01

    Carbon monoxide kinetics were measured in the blood (% carboxyhemoglobin) and alveolar phase (ppM carbon monoxide) after simulated cigarette smoking. Cigarette smoking was siumlated using the same amount of carbon monoxide that 2R1F cigarettes manufactured by the Tobacco Research Institute would contain. Ten boluses of air containing carbon monoxide equivalent to smoking one cigarette were inhaled by six healthy nonsmoker volunteers. Carbon monoxide in the air phase was measured by an Ecolyzer and carboxyhemoglobin was measured by a CO-Oximeter. The mean rise in alveolar carbon monoxide immediately and 20 min after inhaling the last bolus was 3.3 and 3.1 ppM, respectively (p<.005). The mean rise in carboxyhemoglobin immediately and 20 min after inhalation of the last bolus was 0.8 and 0.5% respectively (P<.005). The changes in carboxyhemoglobin were found to be similar to changes that occur when one cigarette is actually smoked.

  6. Photochemical Studies on Aqueous Carboplatin

    Institute of Scientific and Technical Information of China (English)

    刘伟平; 杨懿昆; 阙振寰; 熊惠周

    1994-01-01

    The photochemical products,quantum yields and mechanisms of aqueous Carboplatin havebeen studied at 313 and 254 nm irradiation.Excitation in the ligand field bands 1A1→1A2 and 1A1→1E leads tosubstitution reactions,giving diaquodiammineplatinum and tetraaquoplatinum.And then these complexesundergo thermally hydrolysis and polymerization producing polymeric hydroxo-bridged complexes.Oxygen isnot involved in the reactions.Excitation in the charge-transfer band 1A1→1A2u results in redox reaction.Metallic platinum and diaquodiammineplatinum are formed,respectively,in the absence and the presence ofoxygen.

  7. Catalysis of carbon monoxide methanation by deep sea manganate minerals

    Science.gov (United States)

    Cabrera, A. L.; Maple, M. B.; Arrhenius, G.

    1990-01-01

    The catalytic activity of deep sea manganese nodule minerals for the methanation of carbon monoxide was measured with a microcatalytic technique between 200 and 460 degrees C. The manganate minerals were activated at 248 degrees C by immersion into a stream of hydrogen in which pulses of carbon monoxide were injected. Activation energies for the methanation reaction and hydrogen desorption from the manganate minerals were obtained and compared with those of pure nickel. Similar energy values indicate that the activity of the nodule materials for the reaction appears to be related to the amount of reducible transition metals present in the samples (ca. 11 wt.-%). Since the activity of the nodule minerals per gram is comparable to that of pure nickel, most of the transition metal ions located between manganese oxide layers appear to be exposed and available to catalyze the reaction.

  8. Photochemical Ablation of Organic Solids

    Science.gov (United States)

    Garrison, Barbara

    2004-03-01

    As discovered by Srinivasan in 1982, irradiation of materials by far UV laser light can lead to photochemical ablation, a process distinct from normal thermal ablation in which the laser primarily heats the material. A versatile mesoscopic model for molecular dynamics simulations of the laser ablation phenomena is presented. The model incorporates both the thermal and photochemical events, that is, both heating of the system and UV induced bond-cleavage followed by abstraction and radical-radical recombination reactions. The results from the simulations are compared to experimental data and the basic physics and chemistry for each irradiation regime are discussed. Initial results from polymer ablation simulations will be presented. L. V. Zhigilei, P. B. S. Kodali and B. J. Garrison, J. Phys. Chem. B, 102, 2845-2853 (1998); L. V. Zhigilei and B. J. Garrison, Journal of Applied Physics, 88, 1281-1298 (2000). Y. G. Yingling, L. V. Zhigilei and B. J. Garrison, J. Photochemistry and Photobiology A: Chemistry, 145, 173-181 (2001); Y. G. Yingling and B. J. Garrison, Chem. Phys. Lett., 364, 237-243 (2002).

  9. A Study of Different Doped Metal Cations on the Physicochemical Properties and Catalytic Activities of Ce20 M1 Ox (M=Zr, Cr, Mn, Fe, Co, Sn) Composite Oxides for Nitric Oxide Reduction by Carbon Monoxide.

    Science.gov (United States)

    Deng, Changshun; Li, Min; Qian, Junning; Hu, Qun; Huang, Meina; Lin, Qingjin; Ruan, Yongshun; Dong, Lihui; Li, Bin; Fan, Minguang

    2016-08-05

    This work is mainly focused on investigating the effects of different doped metal cations on the formation of Ce20 M1 Ox (M=Zr, Cr, Mn, Fe, Co, Sn) composite oxides and their physicochemical and catalytic properties for NO reduction by CO as a model reaction. The obtained samples were characterized by using N2 physisorption, X-ray diffraction, laser Raman spectroscopy, UV/Vis diffuse reflectance spectroscopy, inductively coupled plasma atomic emission spectroscopy, X-ray photoelectron spectroscopy, temperature-programmed reduction by hydrogen and by oxygen (H2 -TPR and O2 -TPD), in situ diffuse reflectance infrared Fourier transform spectroscopy, and the NO+CO model reaction. The results imply that the introduction of M(x+) into the lattice of CeO2 increases the specific surface area and pore volume, especially for variable valence metal cations, and enhances the catalytic performance to a great extent. In this regard, increases in the oxygen vacancies, reduction properties, and chemisorbed O2 (-) (and/or O(-) ) species of these Ce20 M1 Ox composite oxides (M refers to variable valence metals) play significant roles in this reaction. Among the samples, Ce20 Cr1 Ox exhibited the best catalytic performance, mainly because it has the best reducibility and more chemisorbed oxygen, and significant reasons for these attributes may be closely related to favorable synergistic interactions of the vacancies and near-surface Ce(3+) and Cr(3+) . Finally, a possible reaction mechanism was tentatively proposed to understand the reactions.

  10. Carbon monoxide conversion by anaerobic bioreactor sludges

    NARCIS (Netherlands)

    Sipma, J.; Stams, A.J.M.; Lens, P.N.L.; Lettinga, G.

    2003-01-01

    Seven different anaerobic sludges from wastewater treatment reactors were screened for their ability to convert carbon monoxide (CO) at 30 and 55degreesC
    Seven different anaerobic sludges from wastewater treatment reactors were screened for their ability to convert carbon monoxide (CO) at 30 and

  11. From Laboratory Studies to the Field Applications of Advanced Oxidation Processes: A Case Study of Technology Transfer from Switzerland to Burkina Faso on the Field of Photochemical Detoxification of Biorecalcitrant Chemical Pollutants in Water

    Directory of Open Access Journals (Sweden)

    S. Kenfack

    2009-01-01

    Full Text Available The Fenton and photo-Fenton detoxification of non-biodegradable chemical pollution in water was investigated under simulated UV light in the laboratory and under direct sunlight in Ouagadougou, Burkina Faso. The laboratory experiments enable one to make a systematic diagnosis among three types of wastewaters, identifying a biorecalcitrant wastewater containing the Chloro-hydroxy-Pryridine (CHYPR. The application of the photo-Fenton process on effluent containing the CHYPR showed not to stimulate the generation of biodegradable by-products. Optimal conditions for detoxification of effluent containing the CHYPR were found at pH=2.8, [Fe2+]=5.2 mM, initial [H2O2]=768 mM, for an effluent concentrated at 2.2 mM of CHYPR. The application of the photochemical process on a field pilot solar photoreactor for the detoxification of water polluted with a pesticide made with Endosulfan showed very promising results, with potential biodegradable effluents obtained at the end of the photochemical treatment. Optimal conditions of the applied study were found at pH=3. [H2O2]=8 mM and [Fe2+]=0.18 mM for an initial concentration of 0.36 mM of Endosulfan.

  12. Photochemical organonitrate formation in wet aerosols

    Science.gov (United States)

    Lim, Yong Bin; Kim, Hwajin; Kim, Jin Young; Turpin, Barbara J.

    2016-10-01

    Water is the most abundant component of atmospheric fine aerosol. However, despite rapid progress, multiphase chemistry involving wet aerosols is still poorly understood. In this work, we report results from smog chamber photooxidation of glyoxal- and OH-containing ammonium sulfate or sulfuric acid particles in the presence of NOx and O3 at high and low relative humidity. Particles were analyzed using ultra-performance liquid chromatography coupled to quadrupole time-of-flight mass spectrometry (UPLC-Q-TOF-MS). During the 3 h irradiation, OH oxidation products of glyoxal that are also produced in dilute aqueous solutions (e.g., oxalic acids and tartaric acids) were formed in both ammonium sulfate (AS) aerosols and sulfuric acid (SA) aerosols. However, the major products were organonitrogens (CHNO), organosulfates (CHOS), and organonitrogen sulfates (CHNOS). These were also the dominant products formed in the dark chamber, indicating non-radical formation. In the humid chamber (> 70 % relative humidity, RH), two main products for both AS and SA aerosols were organonitrates, which appeared at m / z- 147 and 226. They were formed in the aqueous phase via non-radical reactions of glyoxal and nitric acid, and their formation was enhanced by photochemistry because of the photochemical formation of nitric acid via reactions of peroxy radicals, NOx and OH during the irradiation.

  13. Carbon Monoxide: An Essential Signalling Molecule

    Science.gov (United States)

    Mann, Brian E.

    Carbon monoxide (CO), like nitric oxide (NO), is an essential signalling molecule in humans. It is active in the cardiovascular system as a vasodilator. In addition, CO possesses anti-inflammatory, anti-apoptotic and anti-proliferative properties and protects tissues from hypoxia and reperfusion injury. Some of its applications in animal models include suppression of organ graft rejection and safeguarding the heart during reperfusion after cardiopulmonary bypass surgery. CO also suppresses arteriosclerotic lesions following angioplasty, reverses established pulmonary hypertension and mitigates the development of post-operative ileus in the murine small intestine and the development of cerebral malaria in mice as well as graft-induced intimal hyperplasia in pigs. There have been several clinical trials using air-CO mixtures for the treatment of lung-, heart-, kidney- and abdominal-related diseases. This review examines the research involving the development of classes of compounds (with particular emphasis on metal carbonyls) that release CO, which could be used in clinically relevant conditions. The review is drawn not only from published papers in the chemical literature but also from the extensive biological literature and patents on CO-releasing molecules (CO-RMs).

  14. The Carbon Monoxide Tape Recorder

    Science.gov (United States)

    Schoeberl, M. R.; Duncan, B. N.; Douglass, A. R.; Waters, J.; Livesey, N.; Read, W.; Filipiak, M.

    2006-01-01

    Using Aura MLS data we have identified the stratospheric tape recorder in carbon monoxide (CO). Unlike the water vapor tape recorder, which is controlled by upper troposphere processes, the CO tape recorder is linked to seasonal biomass burning. Since CO has a lifetime of only a few months, the CO tape recorder barely extends above 20 km. The tape head for CO appears to be close to 360K near the same location as the water vapor tape head [Read et al, 20041. Both tape heads are below the equatorial cold point tropopause but above the base of the tropical tropopause layer. The tape recorder signal becomes more distinct from 360K to 380K suggesting that convective detrainment of plays a decreasingly important role with altitude. The Global Modeling Initiative chemical transport model forced by the climatology of biomass burning reproduces the CO tape recorder.

  15. Oxidation catalyst

    Science.gov (United States)

    Ceyer, Sylvia T.; Lahr, David L.

    2010-11-09

    The present invention generally relates to catalyst systems and methods for oxidation of carbon monoxide. The invention involves catalyst compositions which may be advantageously altered by, for example, modification of the catalyst surface to enhance catalyst performance. Catalyst systems of the present invention may be capable of performing the oxidation of carbon monoxide at relatively lower temperatures (e.g., 200 K and below) and at relatively higher reaction rates than known catalysts. Additionally, catalyst systems disclosed herein may be substantially lower in cost than current commercial catalysts. Such catalyst systems may be useful in, for example, catalytic converters, fuel cells, sensors, and the like.

  16. Modeling of Carbon Monoxide Removal by Corona Plasma

    Institute of Scientific and Technical Information of China (English)

    FENG Jingwei; SUN Yabing; ZHAO Dayong; ZHENG Zheng; XU Yuewu; YANG Haifeng; ZHU Hongbiao; ZHOU Xiaoxia

    2009-01-01

    Modeling of carbon monoxide (CO) removal by a corona plasma was conducted in this study.The purification efficiency of CO was calculated theoretically and the factors affecting the removal of CO were analyzed.The results showed that the main removal mechanisms of CO were direct dissociation by generated high-energy electrons and indirect oxidation by generated hydroxyl radicals.The purification efficiency of CO was dependent on the plasma parameters,indoor air humidity and initial concentration of CO.Good consistency between the theoretical calculation and the experimental results was observed.

  17. Engineering evidence for carbon monoxide toxicity cases.

    Science.gov (United States)

    Galatsis, Kosmas

    2016-07-01

    Unintentional carbon monoxide poisonings and fatalities lead to many toxicity cases. Given the unusual physical properties of carbon monoxide-in that the gas is odorless and invisible-unorganized and erroneous methods in obtaining engineering evidence as required during the discovery process often occurs. Such evidence gathering spans domains that include building construction, appliance installation, industrial hygiene, mechanical engineering, combustion and physics. In this paper, we attempt to place a systematic framework that is relevant to key aspects in engineering evidence gathering for unintentional carbon monoxide poisoning cases. Such a framework aims to increase awareness of this process and relevant issues to help guide legal counsel and expert witnesses.

  18. Delayed encephalopathy after acute carbon monoxide poisoning

    Directory of Open Access Journals (Sweden)

    Mehmet İbrahim Turan

    2014-03-01

    Full Text Available Carbon monoxide poisoning is a major cause of death following attempted suicide and accidental exposures. Although clinical presentation depends on the duration and the intensity of exposure, the assessment of the severity of intoxication is difficult. A small percentage of patients who show complete initial recovery may develop delayed neurological deficits. Delayed encephalopathy after acute carbon monoxide poisoning is a rare and poor prognosis neurologic disorders and there is no specific treatment. We present a case with early onset of delayed encephalopathy after acute carbon monoxide poisoning with typical cranial imaging findings in a child with atypical history and clinical presentation.

  19. Hypervalence in monoxides and dioxides of superalkali clusters

    Science.gov (United States)

    Cochran, Elizabeth; Meloni, Giovanni

    2014-05-01

    F2Li3, a superalkali cluster, is characterized as having a lower adiabatic ionization energy than its elemental alkali counterpart and, coupled with the presence of complex molecular orbitals, suggests promise for novel bonding possibilities. CBS-QB3 composite method was used to study three distinct cluster isomers, as well as their cationic (+1) and anionic (-1) species, to identify energetic trends and observe geometric changes. Oxides were then generated from these clusters, of which three distinct monoxides and nine dioxides were obtained upon structure optimization. Identical calculations were performed for the oxide species and their charged counterparts. Some of the most stable oxides produced appear to possess hypervalent lithium and oxygen atoms, forming unique structures with exceptional stability.

  20. Photochemical conversion of solar energy.

    Science.gov (United States)

    Balzani, Vincenzo; Credi, Alberto; Venturi, Margherita

    2008-01-01

    Energy is the most important issue of the 21st century. About 85% of our energy comes from fossil fuels, a finite resource unevenly distributed beneath the Earth's surface. Reserves of fossil fuels are progressively decreasing, and their continued use produces harmful effects such as pollution that threatens human health and greenhouse gases associated with global warming. Prompt global action to solve the energy crisis is therefore needed. To pursue such an action, we are urged to save energy and to use energy in more efficient ways, but we are also forced to find alternative energy sources, the most convenient of which is solar energy for several reasons. The sun continuously provides the Earth with a huge amount of energy, fairly distributed all over the world. Its enormous potential as a clean, abundant, and economical energy source, however, cannot be exploited unless it is converted into useful forms of energy. This Review starts with a brief description of the mechanism at the basis of the natural photosynthesis and, then, reports the results obtained so far in the field of photochemical conversion of solar energy. The "grand challenge" for chemists is to find a convenient means for artificial conversion of solar energy into fuels. If chemists succeed to create an artificial photosynthetic process, "... life and civilization will continue as long as the sun shines!", as the Italian scientist Giacomo Ciamician forecast almost one hundred years ago.

  1. Characterization of Fe-Co-Mn catalysts after carbon monoxide hydrogenation

    Energy Technology Data Exchange (ETDEWEB)

    Gonzalez C, S.L.; Serbia, M.A.; Baechler, R.; Orozco, J. [Laboratorio de Cinetica y Catalisis, Departamento de Quimica, Facultad de Ciencias, Universidad de Los Andes, Merida 5101A (Venezuela); e-mail: goncor@ula.ve

    2003-07-01

    An Fe-Co-Mn catalysts series after hydrogenation of carbon monoxide has been characterized. The XRD analysis shows the magnetite as main crystalline phase after reaction, in addition of carbon and carbide phases. All these phases lead to hydrogen consumption and oxidation rate changes on Fe-Co-Mn catalysts. A phase transformation superficial diagram is analysed. (Author)

  2. Carbon Monoxide Silicate Reduction System Project

    Data.gov (United States)

    National Aeronautics and Space Administration — The Carbon Monoxide Silicate Reduction System (COSRS) is a novel technology for producing large quantities of oxygen on the Moon. Oxygen yields of 15 kilograms per...

  3. Protect Yourself from Carbon Monoxide Poisoning

    Centers for Disease Control (CDC) Podcasts

    2007-11-20

    Learn about carbon monoxide - a colorless, odorless gas - and how to protect yourself and your family.  Created: 11/20/2007 by CDC National Center for Environmental Health.   Date Released: 12/4/2007.

  4. Hearing Loss due to Carbon Monoxide Poisoning

    Directory of Open Access Journals (Sweden)

    Amir Houshang Mehrparvar

    2013-01-01

    Full Text Available Carbon monoxide poisoning is one of the rare causes of hearing loss which may cause reversible or irreversible, unilateral or bilateral hearing loss after acute or chronic exposure. In this report, we present a case of bilateral sensorineural hearing loss in a secondary smelting workshop worker after an acute exposure to carbon monoxide. This complication was diagnosed by pure-tone audiometry and confirmed by transient evoked otoacoustic emissions. Hearing loss has not improved after 3 months of followup.

  5. Photochemical dynamics of indolylmaleimide derivatives.

    Science.gov (United States)

    Murakami, Tatsuhiro; Nakazono, Manabu; Kondorskiy, Alexey; Ishida, Toshimasa; Nanbu, Shinkoh

    2012-08-28

    On-the-fly nonadiabatic ab initio molecular dynamics simulations have been carried out for three anionic species of indolylmaleimides (3-(1H-3-indolyl)-2,5-dihydro-1H-2,5-pyrroledione, IM) to clarify the mechanisms of photochemical reactions. The results are obtained for (i) a monovalent anion with a deprotonated indole NH group (IM(-)'), (ii) a monovalent anion with a deprotonated maleimide NH group (IM(-)'') and (iii) a divalent anion with doubly deprotonated indole and the maleimide NH groups (IM(2-)). Quantum chemical calculations are treated at the three state averaged complete-active space self-consistent field level for 6 electrons in 5 orbitals with the cc-pVDZ basis set (CAS (6, 5) SCF/cc-pVDZ). Molecular dynamics simulations are performed with electronically nonadiabatic transitions included using the Zhu-Nakamura version of the trajectory surface hopping (ZN-TSH) method. It is found that the nonadiabatic transitions occur accompanied by the stretching and shrinking motions of the N(7)-C(8) bond in the case of IM(-)' and the C(11)-N(12) bond in IM(2-) rather than the twisting motion of the dihedral angle. We also found that the ultrafast S(2)→ S(1) nonadiabatic transitions occur through the conical intersection (CoIn) right after photoexcitation to S(2) in IM(-)' and IM(2-). Furthermore, the S(1)→ S(0) nonadiabatic transitions are found to take place in IM(-)'. It is concluded that IM(2-) would mainly contribute to the photoemission, because the S(1)← S(0) and S(2)← S(0) transitions of IM(-)'' are dipole-forbidden transitions and, moreover, IM(2-) is found to be the only species to stay in the S(1) state without non-radiative decay.

  6. Toward Carbon Monoxide-Based Therapeutics: Critical Drug Delivery and Developability Issues.

    Science.gov (United States)

    Ji, Xingyue; Damera, Krishna; Zheng, Yueqin; Yu, Bingchen; Otterbein, Leo E; Wang, Binghe

    2016-02-01

    Carbon monoxide (CO) is an intrinsic signaling molecule with importance on par with that of nitric oxide. During the past decade, pharmacologic studies have amply demonstrated the therapeutic potential of carbon monoxide. However, such studies were mostly based on CO inhalation and metal-based CO-releasing molecules. The field is now at the stage that a major effort is needed to develop pharmaceutically acceptable forms of CO for delivery via various routes such as oral, injection, infusion, or topical applications. This review examines the state of the art, discusses the existing hurdles to overcome, and proposes developmental strategies necessary to address remaining drug delivery issues.

  7. Untangling the Energetics and Dynamics of Boron Monoxide Radical Reactions (11BO; X2Sigma+)

    Science.gov (United States)

    2015-04-15

    energy-density molecules and builds up on our previously successful synthesis of higher carbon oxides COx (x=3-6). Higher-order carbon sulfides - carbon...3.1. Crossed Beam Reactions of Boron Monoxide with Acetylene anmd Ethylene (P1, P8) The reaction dynamics of boron monoxide (BO; X2Σ...with acetylene (C2H2; X1Σg+) and with ethylene (C2H4; X1Ag) were investigated under single collision conditions at collision energy of 12 to 13 kJ mol

  8. Disulfide S-monoxides convert xanthine dehydrogenase into oxidase in rat liver cytosol more potently than their respective disulfides.

    Science.gov (United States)

    Sakuma, Satoru; Fujita, Junko; Nakanishi, Masahiko; Wada, Shun-ich; Fujimoto, Yohko

    2008-05-01

    Xanthine oxidase (XO)/xanthine dehydrogenase (XD) oxidizes oxypurines to uric acid, with only the XO form producing reactive oxygen species. In the present study, the effects of cystamine S-monoxide and cystine S-monoxide (disulfide S-monoxides) on the conversion of XD to XO in rat liver were examined. A partially purified enzyme fraction from the rat liver was incubated with xanthine in the presence or absence of NAD+, and the uric acid formed was measured by HPLC. Under basal conditions, XO activity represented about 15% of the total XO plus XD activity. Cystamine S-monoxide and cystine S-monoxide converted XD into XO in a dose-dependent manner, and the concentrations required to increase XO activity by 50% were approximately 1 and 2 microM, respectively. Their respective thiols (cysteamine and cysteine) and disulfides (cystamine and cystine) up to 10 microM showed weak or no effects on the activities of XO and XD and their conversion. Experiments utilizing a sulfhydryl reducing reagent (dithiothreitol) and sulfhydryl modifiers (4,4'-dithiodipyridine and 1-fluoro-2,4-dinitrobenzene) indicated that disulfide S-monoxides-induced conversion of XD to XO occurs via disulfide bridge formation in XD, but not the modification of sulfhydryl groups. These results suggest that disulfide S-monoxides have the potential to increase the generation of reactive oxygen species through the conversion of XD to XO in liver.

  9. Formation of orthorhombic tin dioxide from mechanically milled monoxide powders

    Science.gov (United States)

    Lamelas, F. J.

    2004-12-01

    X-ray scattering measurements are used to show that the metastable orthorhombic phase of tin dioxide is produced by the oxidation of mechanically milled litharge-phase tin monoxide. After milling to a grain size of approximately 20nm, followed by heating to 575°C, the fraction of the orthorhombic phase is approximately 80%. The orthorhombic phase was originally observed in high-pressure experiments, but more recently, it has been produced in a wide variety of thin-film and nanoparticle samples. The data presented here demonstrate the importance of small-grain-size tin monoxide as a precursor in the ambient-pressure synthesis of the orthorhombic phase. This result has practical importance in the production of tin dioxide gas sensors. A more fundamental observation is that the particle size of a precursor phase can have a marked effect on subsequent phases produced during oxidation. Lastly, a formula for determining the orthorhombic fraction in two-phase tin dioxide samples is developed using the method of standard additions.

  10. Space-based observation of volcanic iodine monoxide

    Science.gov (United States)

    Schönhardt, Anja; Richter, Andreas; Theys, Nicolas; Burrows, John P.

    2017-04-01

    Volcanic eruptions inject substantial amounts of halogens into the atmosphere. Chlorine and bromine oxides have frequently been observed in volcanic plumes from different instrumental platforms such as from ground, aircraft and satellites. The present study is the first observational evidence that iodine oxides are also emitted into the atmosphere during volcanic eruptions. Large column amounts of iodine monoxide, IO, are observed in satellite measurements following the major eruption of the Kasatochi volcano, Alaska, in 2008. The IO signal is detected in measurements made both by SCIAMACHY (Scanning Imaging Absorption Spectrometer for Atmospheric CHartographY) on ENVISAT (Environmental Satellite) and GOME-2 (Global Ozone Monitoring Experiment-2) on MetOp-A (Meteorological Operational Satellite A). Following the eruption on 7 August 2008, strongly elevated levels of IO slant columns of more than 4 × 1013 molec cm-2 are retrieved along the volcanic plume trajectories for several days. The retrieved IO columns from the different instruments are consistent, and the spatial distribution of the IO plume is similar to that of bromine monoxide, BrO. Details in the spatial distribution, however, differ between IO, BrO and sulfur dioxide, SO2. The column amounts of IO are approximately 1 order of magnitude smaller than those of BrO. Using the GOME-2A observations, the total mass of IO in the volcanic plume injected into the atmosphere from the eruption of Kasatochi on 7 August 2008, is determined to be on the order of 10 Mg.

  11. Mechanistic insights into chemical and photochemical transformations of bismuth vanadate photoanodes

    OpenAIRE

    Toma, Francesca M.; Cooper, Jason K.; Kunzelmann, Viktoria; McDowell, Matthew T.; Yu, Jie; Larson, David M.; Borys, Nicholas J.; Abelyan, Christine; Beeman, Jeffrey W.; Yu, Kin Man; Yang, Jinhui; Chen, Le; Shaner, Matthew R.; Spurgeon, Joshua; Houle, Frances A.

    2016-01-01

    Artificial photosynthesis relies on the availability of semiconductors that are chemically stable and can efficiently capture solar energy. Although metal oxide semiconductors have been investigated for their promise to resist oxidative attack, materials in this class can suffer from chemical and photochemical instability. Here we present a methodology for evaluating corrosion mechanisms and apply it to bismuth vanadate, a state-of-the-art photoanode. Analysis of changing morphology and compo...

  12. Hemeoxygenase-1 inhibits human myometrial contractility via carbon monoxide and is upregulated by progesterone during pregnancy.

    OpenAIRE

    Acevedo, C H; Ahmed, A

    1998-01-01

    Nitric oxide was proposed as an endogenous inhibitor of myometrial contractility during pregnancy. Carbon monoxide (CO) like nitric oxide increases cGMP and is generated during the degradation of heme to biliverdin IX by hemeoxygenases (HO). Here we report that the expression of both HO-1 (inducible) and HO-2 (constitutive) were > 15-fold higher in pregnant myometrium compared to nonpregnant myometrium (n = 4, P < 0.001, P < 0.005, respectively). Moreover, the activation of the HO-CO pathway ...

  13. Stable isotope composition of atmospheric carbon monoxide. A modelling study

    Energy Technology Data Exchange (ETDEWEB)

    Gromov, Sergey S.

    2014-11-01

    This study aims at an improved understanding of the stable carbon and oxygen isotope composition of the carbon monoxide (CO) in the global atmosphere by means of numerical simulations. At first, a new kinetic chemistry tagging technique for the most complete parameterisation of isotope effects has been introduced into the Modular Earth Submodel System (MESSy) framework. Incorporated into the ECHAM/MESSy Atmospheric Chemistry (EMAC) general circulation model, an explicit treatment of the isotope effects on the global scale is now possible. The expanded model system has been applied to simulate the chemical system containing up to five isotopologues of all carbon- and oxygen-bearing species, which ultimately determine the δ{sup 13}C, δ{sup 18}O and Δ{sup 17}O isotopic signatures of atmospheric CO. As model input, a new stable isotope-inclusive emission inventory for the relevant trace gases has been compiled. The uncertainties of the emission estimates and of the resulting simulated mixing and isotope ratios have been analysed. The simulated CO mixing and stable isotope ratios have been compared to in-situ measurements from ground-based observatories and from the civil-aircraft-mounted CARIBIC-1 measurement platform. The systematically underestimated {sup 13}CO/{sup 12}CO ratios of earlier, simplified modelling studies can now be partly explained. The EMAC simulations do not support the inferences of those studies, which suggest for CO a reduced input of the highly depleted in {sup 13}C methane oxidation source. In particular, a high average yield of 0.94 CO per reacted methane (CH{sub 4}) molecule is simulated in the troposphere, to a large extent due to the competition between the deposition and convective transport processes affecting the CH{sub 4} to CO reaction chain intermediates. None of the other factors, assumed or disregarded in previous studies, however hypothesised to have the potential in enriching tropospheric CO in {sup 13}C, were found significant

  14. Photochemical Hydrogen Doping Induced Embedded Two-Dimensional Metallic Channel Formation in InGaZnO at Room Temperature.

    Science.gov (United States)

    Kim, Myeong-Ho; Lee, Young-Ahn; Kim, Jinseo; Park, Jucheol; Ahn, Seungbae; Jeon, Ki-Joon; Kim, Jeong Won; Choi, Duck-Kyun; Seo, Hyungtak

    2015-10-27

    The photochemical tunability of the charge-transport mechanism in metal-oxide semiconductors is of great interest since it may offer a facile but effective semiconductor-to-metal transition, which results from photochemically modified electronic structures for various oxide-based device applications. This might provide a feasible hydrogen (H)-radical doping to realize the effectively H-doped metal oxides, which has not been achieved by thermal and ion-implantation technique in a reliable and controllable way. In this study, we report a photochemical conversion of InGaZnO (IGZO) semiconductor to a transparent conductor via hydrogen doping to the local nanocrystallites formed at the IGZO/glass interface at room temperature. In contrast to thermal or ionic hydrogen doping, ultraviolet exposure of the IGZO surface promotes a photochemical reaction with H radical incorporation to surface metal-OH layer formation and bulk H-doping which acts as a tunable and stable highly doped n-type doping channel and turns IGZO to a transparent conductor. This results in the total conversion of carrier conduction property to the level of metallic conduction with sheet resistance of ∼16 Ω/□, room temperature Hall mobility of 11.8 cm(2) V(-1) sec(-1), the carrier concentration at ∼10(20) cm(-3) without any loss of optical transparency. We demonstrated successful applications of photochemically highly n-doped metal oxide via optical dose control to transparent conductor with excellent chemical and optical doping stability.

  15. Stratospheric Ozone: Transport, Photochemical Production and Loss

    Science.gov (United States)

    Douglass, A. R.; Kawa, S. R.; Jackman, C. H.

    2003-01-01

    Observations from various satellite instruments (e.g., Total Ozone Mapping Spectrometer (TOMS), Halogen Occultation Experiment (HALOE), Microwave Limb Sounder (MLS)) specify the latitude and seasonal variations of total ozone and ozone as a function of altitude. These seasonal variations change with latitude and altitude partly due to seasonal variation in transport and temperature, partly due to differences in the balance between photochemical production and loss processes, and partly due to differences in the relative importance of the various ozone loss processes. Comparisons of modeled seasonal ozone behavior with observations test the following: the seasonal dependence of dynamical processes where these dominate the ozone tendency; the seasonal dependence of photochemical processes in the upper stratosphere; and the seasonal change in the balance between photochemical and dynamical processes.

  16. Mixing ratios of carbon monoxide in the troposphere

    Energy Technology Data Exchange (ETDEWEB)

    Novelli, P.C.; Steele, L.P. (Univ. of Colorado, Boulder (United States)); Tans, P.P. (NOAA, Boulder, CO (United States))

    1992-12-20

    Carbon monoxide (CO) mixing ratios were measured in air samples collected weekly at eight locations. The air was collected as part of the CMDL/NOAA cooperative flask sampling program (Climate Monitoring and Diagnostics Laboratory, formerly Geophysical Monitoring for Climatic Change, Air Resources Laboratory/National Oceanic and Atmospheric Administration) at Point Barrow, Alaska, Niwot Ridge, Colorado, Mauna Loa and Cape Kumakahi, Hawaii, Guam, Marianas Islands, Christmas Island, Ascension Island and American Samoa. Half-liter or 3-L glass flasks fitted with glass piston stopcocks holding teflon O rings were used for sample collection. CO levels were determined within several weeks of collection using gas chromatography followed by mercuric oxide reduction detection, and mixing ratios were referenced against the CMDL/NOAA carbon monoxide standard scale. During the period of study (mid-1988 through December 1990) CO levels were greatest in the high latitudes of the northern hemisphere (mean mixing ratio from January 1989 to December 1990 at Point Barrow was approximately 154 ppb) and decreased towards the south (mean mixing ratio at Samoa over a similar period was 65 ppb). Mixing ratios varied seasonally, the amplitude of the seasonal cycle was greatest in the north and decreased to the south. Carbon monoxide levels were affected by both local and regional scale processes. The difference in CO levels between northern and southern latitudes also varied seasonally. The greatest difference in CO mixing ratios between Barrow and Samoa was observed during the northern winter (about 150 ppb). The smallest difference, 40 ppb, occurred during the austral winter. The annually averaged CO difference between 71[degrees]N and 14[degrees]S was approximately 90 ppb in both 1989 and 1990; the annually averaged interhemispheric gradient from 71[degrees]N to 41[degrees]S is estimated as approximately 95 ppb. 66 refs., 5 figs., 5 tabs.

  17. A Simple Parallel Photochemical Reactor for Photodecomposition Studies

    Science.gov (United States)

    Xiaobo Chen; Halasz, Sarah M.; Giles, Eric C.; Mankus, Jessica V.; Johnson, Joseph C.; Burda, Clemens

    2006-01-01

    A simple and useful parallel photochemical reactor intended to study the photodecomposition of dyes using semiconductor photocatalysis is presented. The photochemical reactions are followed through time-dependent changes in the ground-state absorption spectra of the dyes.

  18. Photochemical and Nonphotochemical Transformations of Cysteine with Dissolved Organic Matter.

    Science.gov (United States)

    Chu, Chiheng; Erickson, Paul R; Lundeen, Rachel A; Stamatelatos, Dimitrios; Alaimo, Peter J; Latch, Douglas E; McNeill, Kristopher

    2016-06-21

    Cysteine (Cys) plays numerous key roles in the biogeochemistry of natural waters. Despite its importance, a full assessment of Cys abiotic transformation kinetics, products and pathways under environmental conditions has not been conducted. This study is a mechanistic evaluation of the photochemical and nonphotochemical (dark) transformations of Cys in solutions containing chromophoric dissolved organic matter (CDOM). The results show that Cys underwent abiotic transformations under both dark and irradiated conditions. Under dark conditions, the transformation rates of Cys were moderate and were highly pH- and temperature-dependent. Under UVA or natural sunlight irradiations, Cys transformation rates were enhanced by up to two orders of magnitude compared to rates under dark conditions. Product analysis indicated cystine and cysteine sulfinic acid were the major photooxidation products. In addition, this study provides an assessment of the contributions of singlet oxygen, hydroxyl radical, hydrogen peroxide, and triplet dissolved organic matter to the CDOM-sensitized photochemical oxidation of Cys. The results suggest that another unknown pathway was dominant in the CDOM-sensitized photodegradation of Cys, which will require further study to identify.

  19. Pulmonary edema in acute carbon monoxide poisoning

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Kun Sang; Chang, Kee Hyun; Lee, Myung Uk [Seoul National University College of Medicine, Seoul (Korea, Republic of)

    1974-10-15

    Acute carbon monoxide poisoning has frequently occurred in Korean, because of the coal briquette being widely used as fuel in Korean residences. Carbon monoxide poisoning has been extensively studied, but it has been sparsely reported that pulmonary edema may develop in acute CO poisoning. We have noticed nine cases of pulmonary edema in acute CO poisoning last year. Other possible causes of pulmonary edema could be exclude in all cases but one. The purpose of this paper is to describe nine cases of pulmonary edema complicated in acute CO poisoning and discuss the pathogenesis and the prognosis.

  20. 40 CFR 60.103 - Standard for carbon monoxide.

    Science.gov (United States)

    2010-07-01

    ... Refineries § 60.103 Standard for carbon monoxide. Each owner or operator of any fluid catalytic cracking unit... regenerator any gases that contain carbon monoxide (CO) in excess of 500 ppm by volume (dry basis)....

  1. [Carbon monoxide metabolism by photosynthetic bacteria]. Progress report

    Energy Technology Data Exchange (ETDEWEB)

    1989-12-31

    Research continued on the metabolism of carbon monoxide by Rhodospirillum rubrum. This report discusses progress on the activity, induction, inhibition, and spectroscopic analysis of the enzyme Carbon Monoxide Dehydrogenase. (CBS)

  2. Carbon Monoxide Hazards from Small Gasoline Powered Engines

    Science.gov (United States)

    ... Topics Publications and Products Programs Contact NIOSH NIOSH CARBON MONOXIDE Recommend on Facebook Tweet Share Compartir On this Page Recommendations NIOSH Publications Worker Notification Program Carbon Monoxide Hazards from Small Gasoline Powered Engines Many ...

  3. Oxidation of atrazine by photoactivated potassium persulfate in aqueous solutions

    Science.gov (United States)

    Khandarkhaeva, M. S.; Aseev, D. G.; Sizykh, M. R.; Batoeva, A. A.

    2016-11-01

    General laws of the photochemical oxidation of atrazine by inorganic peroxo compounds under the impact of solar radiation are studied. It is found that almost complete conversion of atrazine can be achieved via photochemical oxidation with persulfate after 120 min, but no deep mineralization is observed. The effect an aqueous matrix has on the processes of atrazine degradation in combined oxidation systems is considered.

  4. Simultaneous measurements of carbon monoxide and ozone in the NASA Global Atmospheric Sampling Program (GASP)

    Science.gov (United States)

    Newell, R. E.; Wu, M.-F.

    1985-01-01

    It is noted that the Global Atmospheric Sampling Program (GASP) was intended to establish global baseline values of selected atmospheric constituents that could be used for studies of the dynamics of the sampled region as well as for modeling purposes. Instrument packages were carried on four Boeing 747 aircraft in routine commercial service. Carbon monoxide and ozone data were collected simultaneously from early 1977 to early 1979 when GASP terminated. CO was measured with an infrared absorption analyzer using dual isotope fluorescence. Ozone was measured via absorption of UV light. Correlations between the CO and the O3 are tabulated; they are clearly negative for both troposphere and stratosphere in middle latitudes, indicating that transport processes between the stratosphere and troposphere (discussed) dominate. But in the low latitude troposphere the correlations are positive, indicating the possible influence of photochemical effects.

  5. Material processing with hydrogen and carbon monoxide on Mars

    Science.gov (United States)

    Hepp, Aloysius F.; Landis, Geoffrey A.; Linne, Diane L.

    1991-01-01

    Several novel proposals are examined for propellant production from carbon dioxide and monoxide and hydrogen. Potential uses were also examined of CO as a fuel or as a reducing agent in metal oxide processing as obtained or further reduced to carbon. Hydrogen can be reacted with CO to produce a wide variety of hydrocarbons, alcohols, and other organic compounds. Methanol, produced by Fischer-Tropsch chemistry may be useful as a fuel; it is easy to store and handle because it is a liquid at Mars temperatures. The reduction of CO2 to hydrocarbons such as methane or acetylene can be accomplished with hydrogen. Carbon monoxide and hydrogen require cryogenic temperatures for storage as liquids. Noncryogenic storage of hydrogen may be accomplished using hydrocarbons, inorganic hydrides, or metal hydrides. Noncryogenic storage of CO may be accomplished in the form of iron carbonyl (FE(CO)5) or other metal carbonyls. Low hydrogen content fuels such as acetylene (C2H2) may be effective propellants with low requirements for earth derived resources. The impact on manned Mars missions of alternative propellant production and utilization is discussed.

  6. Controlled generation of uniform spherical LaMnO3, LaCoO3, Mn2O3, and Co3O4 nanoparticles and their high catalytic performance for carbon monoxide and toluene oxidation.

    Science.gov (United States)

    Liu, Yuxi; Dai, Hongxing; Deng, Jiguang; Zhang, Lei; Zhao, Zhenxuan; Li, Xinwei; Wang, Yuan; Xie, Shaohua; Yang, Huanggen; Guo, Guangsheng

    2013-08-01

    Uniform hollow spherical rhombohedral LaMO3 and solid spherical cubic MOx (M = Mn and Co) NPs were fabricated using the PMMA-templating strategy. Hollow spherical LaMO3 and solid spherical MOx NPs possessed surface areas of 21-33 and 21-24 m(2)/g, respectively. There were larger amounts of surface-adsorbed oxygen species and better low-temperature reducibility on/of the hollow spherical LaMO3 samples than on/of the solid spherical MOx samples. Hollow spherical LaMO3 and solid spherical MOx samples outperformed their nanosized counterparts for oxidation of CO and toluene, with the best catalytic activity being achieved over the solid spherical Co3O4 sample for CO oxidation (T50% = 81 °C and T90% = 109 °C) at space velocity = 10,000 mL/(g h) and the hollow spherical LaCoO3 sample for toluene oxidation (T50% = 220 °C and T90% = 237 °C) at space velocity = 20,000 mL/(g h). It is concluded that the higher surface areas and oxygen adspecies concentrations and better low-temperature reducibility are responsible for the excellent catalytic performance of the hollow spherical LaCoO3 and solid spherical Co3O4 NPs. We believe that the PMMA-templating strategy provides an effective route to prepare uniform perovskite-type oxide and transition-metal oxide NPs.

  7. Southern Africa - a giant natural photochemical reactor

    CSIR Research Space (South Africa)

    Diab, RD

    2006-04-01

    Full Text Available The analogy of a ‘giant natural photochemical reactor’ is extended in this paper to the central and southern African tropics, where tropospheric ozone enhancement occurs over a vast geographical area from the Congo to South Africa, and over a long...

  8. VUV laser ablation of polymers. Photochemical aspect

    Science.gov (United States)

    Castex, M. C.; Bityurin, N.; Olivero, C.; Muraviov, S.; Bronnikova, N.; Riedel, D.

    2000-12-01

    A photochemical theory of laser ablation owing to the direct chain scission process is considered in quite general form taking into account the modification of material. The formulas obtained can be used for estimating mechanisms of VUV laser ablation of polymers.

  9. Photochemical Pollution Modeling of Ozone at Metropolitan Area of Porto Alegre - RS/Brazil using WRF/Chem

    Science.gov (United States)

    Cuchiara, G. C.; Carvalho, J.

    2013-05-01

    One of the main problems related to air pollution in urban areas is caused by photochemical oxidants, particularly troposphere ozone (O3), which is considered a harmful substance. The O3 precursors (carbon monoxide CO, nitrogen oxides NOx and hydrocarbons HCs) are predominantly of anthropogenic origin in these areas, and vehicles are the main emission sources. Due to the increased urbanization and industrial development in recent decades, air pollutant emissions have increased likewise, mainly by mobile sources in the highly urbanized and developed areas, such as the Metropolitan Area of Porto Alegre-RS (MAPA). According to legal regulations implemented in Brazil in 2005, which aimed at increasing the fraction of biofuels in the national energy matrix, 2% biodiesel were supposed to be added to the fuel mixture within three years, and up to 5% after eight years of implementation of these regulations. Our work performs an analysis of surface concentrations for O3, NOx, CO, and HCs through numerical simulations with WRF/Chem (Weather Research and Forecasting model with Chemistry). The model is validated against observational data obtained from the local urban air quality network for the period from January 5 to 9, 2009 (96 hours). One part of the study focused on the comparison of simulated meteorological variables, to observational data from two stations in MAPA. The results showed that the model simulates well the diurnal evolution of pressure and temperature at the surface, but is much less accurate for wind speed. Another part included the evaluation of model results of WRF/Chem for O3 versus observed data at air quality stations Esteio and Porto Alegre. Comparisons between simulated and observed O3 revealed that the model simulates well the evolution of the observed values, but on many occasions the model did not reproduce well the maximum and minimum concentrations. Finally, a preliminary quantitative sensitivity study on the impact of biofuel on the

  10. Arctic chlorine monoxide observations during spring 1993 over Thule, Greenland, and implications for ozone depletion

    Science.gov (United States)

    Shindell, D. T.; Reeves, J. M.; Emmons, L. K.; De Zafra, R. L.

    1994-01-01

    We have determined the vertical distribution of chlorine monoxide (ClO), from measurements of pressure-broadened molecular-emission spectra made over Thule, Greenland, during the 1993 Arctic spring. The measurements show a weak lower stratospheric layer of chlorine monoxide inside the vortex in late February, which was, however, significantly greater in mixing ratio than that seen in observations we made in the spring of 1992. ClO was also observed in much smaller quantities in early to mid-March 1993 when Thule was outside the vortex. The amount of ClO within the vortex was severely reduced by the time it returned over Thule in late March. This reduction occurred several weeks earlier relative to the winter solstice than the decline of ClO inside the Antarctic vortex in 1993. The enhanced Arctic lower stratospheric layer seen in late February 1993 at a nearly equivalent photochemical period, and beyond. We have calculated daily ozone loss rates, due primarily to the dimer chlorine catalytic cycle, from both sets of measurements. The vertical integral of the Arctic daily percentage ozone loss when the largest ClO levels were present, at the end of February, is found to be approximately one quarter of that in the Antarctic at a photochemical period only 1 week later. The relative weakness of daily ozone depletion, combined with the early disappearance of ClO in the Arctic, suggests that hemispheric dilution by ozone-poor air from within the Arctic vortex is unlikely to be sufficient to explain the historically extreme loss of midlatitude northern hemisphere ozone which began in 1992 and persisted throughout 1993.

  11. Arctic chlorine monoxide observations during spring 1993 over Thule, Greenland, and implications for ozone depletion

    Science.gov (United States)

    Shindell, D. T.; Reeves, J. M.; Emmons, L. K.; de Zafra, R. L.

    1994-12-01

    We have determined the vertical distribution of chlorine monoxide (ClO), from measurements of pressure-broadened molecular-emission spectra made over Thule, Greenland, during the 1993 Arctic spring. The measurements show a weak lower stratospheric layer of chlorine monoxide inside the vortex in late February, which was, however, significantly greater in mixing ratio than that seen in observations we made in the spring of 1992. ClO was also observed in much smaller quantities in early to mid-March 1993 when Thule was outside the vortex. The amount of ClO within the vortex was severely reduced by the time it returned over Thule in late March. This reduction occurred several weeks earlier relative to the winter solstice than the decline of ClO inside the Antarctic vortex in 1993. The enhanced Arctic lower stratospheric layer seen in late February 1993 had a peak mixing ratio of about 0.5 parts per billion by volume (ppbv), slightly less than a factor of 3 smaller than that observed in the Antarctic in 1993 at a nearly equivalent photochemical period, and beyond. We have calculated daily ozone loss rates, due primarily to the dimer chlorine catalytic cycle, from both sets of measurements. The vertical integral of the Arctic daily percentage ozone loss when the largest ClO levels were present, at the end of February, is found to be approximately one quarter of that in the Antarctic at a photochemical period only 1 week later. The relative weakness of daily ozone depletion, combined with the early disappearance of ClO in the Arctic, suggests that hemispheric dilution by ozone-poor air from within the Arctic vortex is unlikely to be sufficient to explain the historically extreme loss of midlatitude northern hemisphere ozone which began in 1992 and persisted throughout 1993.

  12. Assessment of carbon monoxide values in smokers: a comparison of carbon monoxide in expired air and carboxyhaemoglobin in arterial blood

    DEFF Research Database (Denmark)

    Andersson, Mette F; Møller, Ann M

    2010-01-01

    Smoking increases perioperative complications. Carbon monoxide concentrations can estimate patients' smoking status and might be relevant in preoperative risk assessment. In smokers, we compared measurements of carbon monoxide in expired air (COexp) with measurements of carboxyhaemoglobin (COHb...

  13. Hearing Loss due to Carbon Monoxide Poisoning

    DEFF Research Database (Denmark)

    Mehrparvar, Amir Houshang; Davari, Mohammad Hossein; Mollasadeghi, Abolfazl

    2013-01-01

    Carbon monoxide poisoning is one of the rare causes of hearing loss which may cause reversible or irreversible, unilateral or bilateral hearing loss after acute or chronic exposure. In this report, we present a case of bilateral sensorineural hearing loss in a secondary smelting workshop worker...

  14. Study of electrocatalytic properties of iridium carbonyl cluster and rhodium carbonyl cluster compounds for the oxygen reduction and hydrogen oxidation reactions in 0.5 MH{sub 2}SO{sub 4} in presence and absence of methanol and carbon monoxide, respectively

    Energy Technology Data Exchange (ETDEWEB)

    Uribe-Godinez, J.; Borja-Arco, E.; Castellanos, R.H. [Centro de Investigacion y Desarrollo Tecnologico en Electroquimica, Escobedo (Mexico); Jimenez-Sandoval, O. [Centro de Investigacion y de Estudios Avanzados del Inst. Politecnico Nacional, Querataro (Mexico)

    2006-07-01

    The suitability of carbonyl cluster compounds as a substitute to platinum (Pt) in fuel cell catalysts was investigated. Iridium (Ir{sub 4}(CO){sub 12} and rhodium (Rh{sub 6}(CO){sub 116}) cluster compounds were investigated as potential new electrocatalysts for oxygen reduction reaction (ORR) in the presence and absence of methanol at different concentrations, as well as for the hydrogen oxidation reaction (HOR) with pure hydrogen and a hydrogen/carbon monoxide mixture. The materials were studied using room temperature rotating disk electrode (RDE) measurements and cyclic and linear sweep voltammetry techniques (LSV). Tafel slope and exchange current density were calculated using the LSV polarization curves. Cyclic voltamperometry results suggested that the electrocatalysts were tolerant to methanol. However, electrochemical behaviour of the materials altered in the presence of CO, and peaks corresponding to CO oxidation were observed in both cases. The rhodium carbonyl showed a higher current density for the ORR than the iridium carbonyl. The current potential curves in the presence of methanol were similar to those obtained without methanol. Results confirmed the tolerance properties of the materials to perform the ORR. Decreased current density values were observed during HOR, and were attributed to changes in the hydrogen solubility and diffusion coefficient due to the presence of CO. The Tafel slopes indicated that the mechanics of the HOR were Heyrovsky-Volmer. Results showed that the materials are capable of performing both ORR and HOR in an acid medium. It was noted that the iridium carbonyl cluster followed a 4-electron transfer mechanism towards the formation of water. It was concluded that the compounds are suitable for use as both cathodes and anodes in proton exchange membrane fuel cells (PEMFCs) and as cathodes in direct methanol fuel cells (DMFCs). 3 refs., 2 tabs., 3 figs.

  15. Surface chemistry for stable and smart molecular and biomolecular interfaces via photochemical grafting of alkenes.

    Science.gov (United States)

    Wang, Xiaoyu; Landis, Elizabeth C; Franking, Ryan; Hamers, Robert J

    2010-09-21

    Many emerging fields such as biotechnology and renewable energy require functionalized surfaces that are "smart" and highly stable. Surface modification schemes developed previously have often been limited to simple molecules or have been based on weakly bound layers that have limited stability. In this Account, we report on recent developments enabling the preparation of molecular and biomolecular interfaces that exhibit high selectivity and unprecedented stability on a range of covalent materials including diamond, vertically aligned carbon nanofibers, silicon, and metal oxides. One particularly successful pathway to ultrastable interfaces involves the photochemical grafting of organic alkenes to the surfaces. Bifunctional alkenes with a suitable functional group at the distal end can directly impart functionality and can serve as attachment points for linking complex structures such as DNA and proteins. The successful application of photochemical grafting to a surprisingly wide range of materials has motivated researchers to better understand the underlying photochemical reaction mechanisms. The resulting studies using experimental and computational methods have provided fundamental insights into the electronic structure of the molecules and the surface control photochemical reactivity. Such investigations have revealed the important role of a previously unrecognized process, photoelectron emission, in initiating photochemical grafting of alkenes to surfaces. Molecular and biomolecular interfaces formed on diamond and other covalent materials are leading to novel types of molecular electronic interfaces. For example, electrical, optical, or electromechanical structures that convert biological information directly into analytical signals allow for direct label-free detection of DNA and proteins. Because of the preferential adherence of molecules to graphitic edge-plane sites, the grafting of redox-active species to vertically aligned carbon nanofibers leads to

  16. Using of Photochemical H2O2/UVC Decontamination Cell for Heavily Polluted Waters

    OpenAIRE

    Žebrák, R.; Mašín, P.; Klusoň, P. (Petr); Krystyník, P. (Pavel)

    2014-01-01

    The presented contribution focuses on the complex study of the pilot-scale photochemical H2O2/UVC system arranged as the ex-situ decontamination cell for heavily polluted waters (contamination with organic substances. The method principle comprises the rational decomposition of hydrogen peroxide induced by UV-C (254 nm). The produced OH radicals are very efficient oxidation species enabling the direct destruction of wide spectrum of organic compounds (polyaromatic hydrocarbons, chlorinat...

  17. Photochemical preparation of sub-wavelength heterogeneous laser-induced periodic surface structures.

    Science.gov (United States)

    Kim, Hee-Cheol; Reinhardt, Hendrik; Hillebrecht, Pierre; Hampp, Norbert A

    2012-04-17

    Laser-induced periodic surface structures (LIPSS) are a phenomenon caused by interaction of light with solid surfaces. We present a photochemical concept which uses LIPSS-related light intensity patterns for the generation of heterogeneous nanostructures. The process facilitates arbitrary combinations of substrate and LIPSS-pattern materials. An efficient method for the generation of organometallic hybrid-nanowire arrays on porous anodic aluminum oxide is demonstrated.

  18. Suppressing photochemical reactions with quantized light fields

    CERN Document Server

    Galego, Javier; Feist, Johannes

    2016-01-01

    Photoisomerization, i.e., a change of molecular structure after absorption of a photon, is one of the most fundamental photochemical processes. It can perform desirable functionality, e.g., as the primary photochemical event in human vision, where it stores electronic energy in the molecular structure, or for possible applications in solar energy storage and as memories, switches, and actuators; but it can also have detrimental effects, for example as an important damage pathway under solar irradiation of DNA, or as a limiting factor for the efficiency of organic solar cells. While photoisomerization can be avoided by shielding the system from light, this is of course not a viable pathway for approaches that rely on the interaction with external light (such as solar cells or solar energy storage). Here, we show that strong coupling of organic molecules to a confined light mode can be used to strongly suppress photoisomerization, and thus convert molecules that normally show fast photodegradation into photosta...

  19. Photochemical degradation of crude oil in seawater

    Institute of Scientific and Technical Information of China (English)

    YANG Guipeng; ZHANG Li; SUN Xiaojing; JING Weiwen

    2006-01-01

    Photochemical degradation of crude oil in seawater is an important issue in marine environmental protection and is studied in this work. Results showed that petroleum hydrocarbons could be effectively degraded by the irradiation of high-pressure mercury light or natural sunlight. Photochemical reaction was controlled by various factors including light source, aquatic medium, heavy metal ion and photo-sensitizer. The rate of photo-degradation was fast at the initial stage of exposure, exhibiting a first-order reaction kinetic behavior. However, after irradiation for a few hours, the concentration of water-soluble fraction (WSF) of petroleum hydrocarbons stabilized. For all experimental conditions, the range of the photo-degradation rate is from 0.001 3 to 0.005 7/min.

  20. Photochemical Escape of Oxygen from Early Mars

    CERN Document Server

    Zhao, Jinjin

    2015-01-01

    Photochemical escape is an important process for oxygen escape from present Mars. In this work, a 1-D Monte-Carlo Model is developed to calculate escape rates of energetic oxygen atoms produced from O2+ dissociative recombination reactions (DR) under 1, 3, 10, and 20 times present solar XUV fluxes. We found that although the overall DR rates increase with solar XUV flux almost linearly, oxygen escape rate increases from 1 to 10 times present solar XUV conditions but decreases when increasing solar XUV flux further. Analysis shows that atomic species in the upper thermosphere of early Mars increases more rapidly than O2+ when increasing XUV fluxes. While the latter is the source of energetic O atoms, the former increases the collision probability and thus decreases the escape probability of energetic O. Our results suggest that photochemical escape be a less important escape mechanism than previously thought for the loss of water and/or CO2 from early Mars.

  1. [Photochemical degradation of chlorpyrifos in water].

    Science.gov (United States)

    Wu, Xiangwei; Hua, Rimao; Tang, Feng; Li, Xuede; Cao, Haiqun; Yue, Yongde

    2006-07-01

    In this paper, the effects of different light sources, temperature, pH, and water quality on the photochemical degradation of clilorpyrifos in water were examined under natural and simulated solar irradiation. The results showed that the photochemical degradation of chlorpyrifos in water followed the first order reaction, and its half-life was 0.62, 6.92, 19.74 and 22.50 h under high pressure mercury lamp (HPML), xenon lamp (XL), ultraviolet lamp (UV), and sunlight (SL) irradiation, respectively. Temperature had a significant effect on the degradation rate of chlorpyrifos, which was increased with increasing temperature and reached the maximum at 35 degrees C. The degradation rate of chlorpyrifos was stable both in acid and in neutral buffer solution, but enhanced in alkaline buffer solution. Water quality also had a significant effect, with a decreasing degradation rate of chlorpyrifos in the sequence of distilled water > tap water > river water > lake wate > paddy water.

  2. Recovery of energy metabolism in rat brain after carbon monoxide hypoxia.

    OpenAIRE

    Brown, S D; Piantadosi, C. A.

    1992-01-01

    Carbon monoxide (CO) may inhibit mitochondrial electron transport in the brain and increase the toxic effects of the gas. This hypothesis was investigated in anesthetized rats during CO exposure and recovery at either normobaric or hyperbaric O2 concentrations. During exposure and recovery, we measured the oxidation level of cerebrocortical cytochrome c oxidase by differential spectroscopy and biochemical metabolites known to reflect aerobic energy provision in the brain. CO exposure (HbCO = ...

  3. Iron-catalyzed photochemical transformation of benzoic acid in atmospheric liquids: Product identification and reaction mechanisms

    Science.gov (United States)

    Deng, Yiwei; Zhang, Kai; Chen, Hao; Wu, Taixing; Krzyaniak, Metthew; Wellons, Amina; Bolla, Dawn; Douglas, Kenneth; Zuo, Yuegang

    This study investigated iron-catalyzed photochemical oxidation of benzoic acid (BA), one of the major photodegradation products of petroleum hydrocarbons, under sunlight or monochromatic light irradiation in a wavelength range of 254-419 nm. The photochemical degradation of BA in the absence of iron (III) occurred at irradiation wavelengths below 300 nm. The photochemical transformation of BA in the presence Fe(III) was observed at both 254, 350, 419 nm and under solar irradiation. The half-life for the photodegradation of BA (100 μM) was 160±20 min in the presence of 20 μM Fe(III) at pH 3.20 on sunny August days at noon time. The degradation rate increased with increasing concentration of Fe(III). The reaction products were separated and identified using capillary electrophoresis (CE), gas chromatography/mass spectrometry (GC/MS) and UV-Visible spectrophotometry. The major reaction products were 2-hydroxybenzoic, 3-hydroxybenzoic and 4-hydroxybenzoic acids. Hydrogen peroxide (H 2O 2) and Fe(II) species were also formed during the photochemical reactions. The proposed reaction mechanisms include the photoexcitation of Fe(III) hydroxide complexes to form Fe(II) ions and hydroxyl radicals (OH rad ) that attack ortho, meta and para positions of BA to form corresponding monohydroxybenzoic acids and H 2O 2. The monohydroxybenzoic acids formed further react with hydroxyl and surperoxide radicals (HO 2- rad /O 2- rad ) to yield dihydroxybenzoic acids in atmospheric water droplets.

  4. Atomic chlorine concentrations derived from ethane and hydroxyl measurements over the equatorial Pacific Ocean: Implication for dimethyl sulfide and bromine monoxide

    Science.gov (United States)

    Wingenter, Oliver W.; Sive, Barkley C.; Blake, Nicola J.; Blake, Donald R.; Rowland, F. Sherwood

    2005-10-01

    Atomic chlorine and bromine monoxide concentrations ([Cl] and [BrO]) and dimethyl sulfide (DMS) sea-air fluxes are estimated from data collected during a Lagrangian flight made near Christmas Island (2°N, 157°W) during August 1996 aboard the NASA P3-B aircraft. Intensive hydrocarbon sampling began in the surface layer (SL) one-half hour after sunrise and continued until ˜1300 local solar time. Our empirical model includes in situ observations of hydroxyl [HO] and precise measurements of ethane (C2H6) mixing ratios. Ethane was ˜40 pptv higher in the buffer layer (BuL) than in the SL, thus vertical exchange tended to replace any C2H6 that was photochemically removed in the SL. In spite of this, SL C2H6 mixing ratios decreased significantly during the flight. Using only the measured [HO] and estimated vertical mixing, our mass balance equation cannot explain all of the observed SL C2H6 loss. However, when an initial [Cl] of 8.4 (±2.0) × 104 Cl cm-3, decreasing to 5.7 (±2.0) × 104 Cl cm-3 at midday, is included, the observed and estimated C2H6 values are in excellent agreement. Using our [Cl], we estimate a DMS flux a factor of 2 higher than when HO is the only oxidant considered. This flux estimate, when compared to that derived by Lenschow et al. (1999), suggests that if the differences are real, we may be missing a loss term. Best agreement occurs when an average BrO mixing ratio of 1.3 (±1.3) pptv is included in our mass balance equation.

  5. Photochemical Phenomenology Model for the New Millennium

    Science.gov (United States)

    Bishop, James; Evans, J. Scott

    2001-01-01

    The "Photochemical Phenomenology Model for the New Millennium" project tackles the issue of reengineering and extension of validated physics-based modeling capabilities ("legacy" computer codes) to application-oriented software for use in science and science-support activities. While the design and architecture layouts are in terms of general particle distributions involved in scattering, impact, and reactive interactions, initial Photochemical Phenomenology Modeling Tool (PPMT) implementations are aimed at construction and evaluation of photochemical transport models with rapid execution for use in remote sensing data analysis activities in distributed systems. Current focus is on the Composite Infrared Spectrometer (CIRS) data acquired during the CASSINI flyby of Jupiter. Overall, the project has stayed on the development track outlined in the Year 1 annual report and most Year 2 goals have been met. The issues that have required the most attention are: implementation of the core photochemistry algorithms; implementation of a functional Java Graphical User Interface; completion of a functional CORBA Component Model framework; and assessment of performance issues. Specific accomplishments and the difficulties encountered are summarized in this report. Work to be carried out in the next year center on: completion of testing of the initial operational implementation; its application to analysis of the CASSINI/CIRS Jovian flyby data; extension of the PPMT to incorporate additional phenomenology algorithms; and delivery of a mature operational implementation.

  6. How are radicals (re)generated in photochemical ATRP?

    Science.gov (United States)

    Ribelli, Thomas G; Konkolewicz, Dominik; Bernhard, Stefan; Matyjaszewski, Krzysztof

    2014-09-24

    The polymerization mechanism of photochemically mediated Cu-based atom-transfer radical polymerization (ATRP) was investigated using both experimental and kinetic modeling techniques. There are several distinct pathways that can lead to photochemical (re)generation of Cu(I) activator species or formation of radicals. These (re)generation pathways include direct photochemical reduction of the Cu(II) complexes by excess free amine moieties and unimolecular reduction of the Cu(II) complex, similar to activators regenerated by electron-transfer (ARGET) ATRP processes. Another pathway is photochemical radical generation either directly from the alkyl halide, ligand, or via interaction of ligand with either monomer or with alkyl halides. These photochemical radical generation processes are similar to initiators for continuous activator regeneration (ICAR) ATRP processes. A series of model experiments, ATRP reactions, and kinetic simulations were performed to evaluate the contribution of these reactions to the photochemical ATRP process. The results of these studies indicate that the dominant radical (re)generation reaction is the photochemical reduction of Cu(II) complexes by free amines moieties (from amine containing ligands). The unimolecular reduction of the Cu(II) deactivator complex is not significant, however, there is some contribution from ICAR ATRP reactions involving the interaction of alkyl halides and ligand, ligand with monomer, and the photochemical cleavage of the alkyl halide. Therefore, the mechanism of photochemically mediated ATRP is consistent with a photochemical ARGET ATRP reaction dominating the radical (re)generation.

  7. Mathematical Modeling of Photochemical Air Pollution.

    Science.gov (United States)

    McRae, Gregory John

    Air pollution is an environmental problem that is both pervasive and difficult to control. An important element of any rational control approach is a reliable means for evaluating the air quality impact of alternative abatement measures. This work presents such a capability, in the form of a mathematical description of the production and transport of photochemical oxidants within an urban airshed. The combined influences of advection, turbulent diffusion, chemical reaction, emissions and surface removal processes are all incorporated into a series of models that are based on the species continuity equations. A delineation of the essential assumptions underlying the formulation of a three-dimensional, a Lagrangian trajectory, a vertically integrated and single cell air quality model is presented. Since each model employs common components and input data the simpler forms can be used for rapid screening calculations and the more complex ones for detailed evaluations. The flow fields, needed for species transport, are constructed using inverse distance weighted polynomial interpolation techniques that map routine monitoring data onto a regular computational mesh. Variational analysis procedures are then employed to adjust the field so that mass is conserved. Initial concentration and mixing height distributions can be established with the same interpolation algorithms. Subgrid scale turbulent transport is characterized by a gradient diffusion hypothesis. Similarity solutions are used to model the surface layer fluxes. Above this layer different treatments of turbulent diffusivity are required to account for variations in atmospheric stability. Convective velocity scaling is utilized to develop eddy diffusivities for unstable conditions. The predicted mixing times are in accord with results obtained during sulfur hexafluoride (SF(,6)) tracer experiments. Conventional models are employed for neutral and stable conditions. A new formulation for gaseous deposition fluxes

  8. Photosynthetic carbon monoxide metabolism by sugarcane leaves

    Energy Technology Data Exchange (ETDEWEB)

    Kortschak, H.P.; Nickell, L.G.

    1973-01-01

    The photosynthetic carbon monoxide metabolism by sugarcane was studied to determine whether substantial quantities of CO are removed from the air by fields in Hawaii. Leaves metabolized low CO concentrations photosynthetically, with sucrose as an end product. Rates of uptake were of the order of 10/sup -4/ power mg/d sq m/hr. This was to low to be significant in removing CO from the atmosphere.

  9. Sensorineural Hearing Loss following Carbon Monoxide Poisoning

    Directory of Open Access Journals (Sweden)

    Joseph P. Pillion

    2012-01-01

    Full Text Available A case study is presented of a 17-year-old male who sustained an anoxic brain injury and sensorineural hearing loss secondary to carbon monoxide poisoning. Audiological data is presented showing a slightly asymmetrical hearing loss of sensorineural origin and mild-to-severe degree for both ears. Word recognition performance was fair to poor bilaterally for speech presented at normal conversational levels in quiet. Management considerations of the hearing loss are discussed.

  10. Bioavialability of Dom Photochemically Released from Resuspended Sediments

    Science.gov (United States)

    Avery, G. B., Jr.; Rainey, D. H.; Mead, R. N.; Skrabal, S. A.; Kieber, R. J.; Felix, J. D.; Helms, J. R.

    2016-02-01

    Little is known regarding the bioavailability of dissolved organic matter (DOM) released photochemically from resuspended estuarine sediments. Sediments were collected from two sites along the Cape Fear River estuary, NC, USA, size fractionated in 0.2 µm filtered Gulf Stream seawater and exposed to simulated sunlight for six hours. Light exposed samples resulted in increases of dissolved organic carbon (DOC) (34 ± 3 µM), chromophoric dissolved organic matter (CDOM) (a300nm, 2.7 m-1), and fluorescent dissolved organic matter (FDOM) (78.6 quinine sulfate equivalents (QSE)) compared to dark controls. Ultra high resolution mass spectrometric characterization indicated the photoreleased DOM was more oxidized and condensed based upon van Kreevlan analysis. Samples were then filtered and inoculated to a final ratio of 4% with coastal water sample filtered through a100 µm net to remove larger grazing organisms and particles while keeping most of bacterial community intact. All three parameters were monitored during a 30 day-long incubation in the dark to assess biological consumption and alteration. Previously light exposed samples had double (20 vs. 9 µM) the amount of DOC consumed compared to samples not previously exposed to light and twice the loss of CDOM (a300nm, 0.6 vs. 0.3 m-1) compared to samples not previously exposed to light. Previously light exposed samples resulted in a threefold loss of FDOM (9.5 QSE) compared to samples not previously exposed to light (2.8 QSE). Results of this study are important because they demonstrate dissolved organic matter released photochemically from resuspended sediments is more bioavailable than ambient material likely fueling secondary productivity and impacting ecosystem functioning in coastal regions.

  11. Photochemical synthesis of mono and bimetallic nanoparticles and their use in catalysis

    Science.gov (United States)

    Pardoe, Andrea

    2011-07-01

    Nanomaterials have become a popular topic of research over the years because of their many important applications. It can be a challenge to stabilize the particles at a nanometer size, while having control over their surface features. Copper nanoparticles were synthesized photochemically using a photogenerated radical allowing spatial and temporal control over their formation. The synthesis was affected by the stabilizers used, which changed the size, dispersity, rate of formation, and oxidation rate. Copper nanoparticles suffer from their fast oxidation in air, so copper-silver bimetallic nanoparticles were synthesized in attempts to overcome the oxidation of copper nanoparticles. Bimetallic nanoparticles were synthesized, but preventing the oxidation of the copper nanoparticles proved difficult. One important application of nanoparticles that was explored here is in catalyzing organic reactions. Because of the fast oxidation of copper nanoparticles, silver nanoparticles were synthesized photochemically on different supports including TiO2 and hydrotalcite (HTC). Their catalytic efficiency was tested using alcohol oxidations. Different silver nanoparticle shapes (decahedra and plates) were compared with the spheres to see the different catalytic efficiencies.

  12. Study of the catalytic activity of pure or cerium-containing thoria in the catalytic oxidation of carbon monoxide (1963); Etude de l'activite catalytique de la thorine pure ou contenant du cerium. Dans l'oxydation de l'oxyde de carbone (1963)

    Energy Technology Data Exchange (ETDEWEB)

    Veron, J. [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

    1963-07-01

    We have undertaken research into the oxidation of carbon monoxide on pure thoria prepared by the decomposition of thorium nitrate, and on the same oxide containing small amounts of cerium. The results we have obtained, both as concerns the chemisorption of the various gases as well as the conductivity of the absorbent and the kinetics of the oxidation itself, appear to be quite coherent. The following steps occur: 1) The carbon monoxide is adsorbed on a clean catalyst surface, the oxygen remaining un-adsorbed. 2) The oxygen is adsorbed on a previously adsorbed carbon, monoxide layer, and reacts to give carbon dioxide (no role being played by the lattice oxygen). This behaviour is usual for a p-type semiconductor. We have in fact confirmed that semi-conductivity is of this type, and the gas-solid interactions can be written: (1) CO{sub (g)} {r_reversible} CO{sup +}{sub (a)} + e{sup -} (2) CO{sup +} 1/2 O{sub 2(g)} + 2 e{sup -} {yields} CO{sup -}{sub 2(a)} (3) CO{sup -}{sub 2(a)} {r_reversible} CO{sub 2(g)} + e{sup -} The kinetic equation obtained by supposing that step (2) is the slowest, makes it possible to deduce correctly the experimental results which can be expressed as: dp / dt = k (P{sup 0.3}{sub CO} x P{sup 0.5}{sub O{sub 2}}) / (1+ k' x P{sub CO{sub 2}}) The influence of the addition of small amounts of cerium can also be explained logically by this process; there is in fact both a decrease in the conductivity and an increase in the catalytic activity, this being characteristic, according to VOLKENSTEIN [52] of an n-type rate-determining reaction occurring on a p-type semi-conductor. We believe that these first results could be advantageously complemented by a study of thoria prepared by other means and doped differently. (author) [French] Nous avons entrepris l'etude de l'oxydation de l'oxyde de carbone sur la thorine pure preparee par decomposition du nitrate de thorium, et sur le meme oxyde renfermant de petites quantites de cerium

  13. Effect of photochemical ageing on the ice nucleation properties of diesel and wood burning particles

    Science.gov (United States)

    Chou, C.; Kanji, Z. A.; Stetzer, O.; Tritscher, T.; Chirico, R.; Heringa, M. F.; Weingartner, E.; Prévôt, A. S. H.; Baltensperger, U.; Lohmann, U.

    2013-01-01

    A measurement campaign (IMBALANCE) conducted in 2009 was aimed at characterizing the physical and chemical properties of freshly emitted and photochemically aged combustion particles emitted from a log wood burner and diesel vehicles: a EURO3 Opel Astra with a diesel oxidation catalyst (DOC) but no particle filter and a EURO2 Volkswagen Transporter TDI Syncro without emission aftertreatment. Ice nucleation experiments in the deposition and condensation freezing modes were conducted with the Portable Ice Nucleation Chamber (PINC) at three nominal temperatures, -30 °C, -35 °C and -40 °C. Freshly emitted diesel particles showed ice formation only at -40 °C in the deposition mode at 137% relative humidity with respect to ice (RHi) and 92% relative humidity with respect to water (RHw), and photochemical ageing did not play a role in modifying their ice nucleation behaviour. Only one diesel experiment where α-pinene was added for the ageing process, showed an ice nucleation enhancement at -35 °C. Wood burning particles also act as ice nuclei (IN) at -40 °C in the deposition mode at the same conditions as for diesel particles and photochemical ageing also did not alter the ice formation properties of the wood burning particles. Unlike diesel particles, wood burning particles form ice via condensation freezing at -35 °C whereas no ice nucleation was observed at -30 °C. Photochemical ageing did not affect the ice nucleation ability of the diesel and wood burning particles at the three different temperatures investigated but a broader range of temperatures below -40 °C need to be investigated in order to draw an overall conclusion on the effect of photochemical ageing on deposition/condensation ice nucleation across the entire temperature range relevant to cold clouds.

  14. Effect of photochemical aging on the ice nucleation properties of diesel and wood burning particles

    Science.gov (United States)

    Chou, C.; Stetzer, O.; Tritscher, T.; Chirico, R.; Heringa, M. F.; Kanji, Z. A.; Weingartner, E.; Prévôt, A. S. H.; Baltensperger, U.; Lohmann, U.

    2012-06-01

    A measurement campaign (IMBALANCE) was conducted in 2009 and aimed at characterizing the physical and chemical properties of freshly emitted and photochemically aged combustion particles emitted from a log wood burner and diesel vehicles: a EURO3 Opel Astra with a diesel oxidation catalyst (DOC) but no particle filter and a EURO2 Volkswagen Transporter TDI Syncro with no emission after-treatment. Ice nucleation experiments in the deposition and condensation freezing modes were conducted with the Portable Ice Nucleation Chamber (PINC) at three nominal temperatures, -30 °C, -35 °C and -40 °C. Freshly emitted diesel particles showed ice formation only at -40 °C in the deposition mode at 137% relative humidity with respect to ice (RHi) and 92% relative humidity with respect to water (RHw), and photochemical aging did not play a role in modifying their ice nucleation behavior. Only one diesel experiment where α-pinene was added, showed an ice nucleation enhancement after the aging at -35 °C. Wood burning particles also act as ice nuclei (IN) at -40 °C in the deposition mode at the same conditions as for diesel particles and photochemical aging did also not alter the ice formation properties of the wood burning particles. Unlike diesel particles, wood burning particles form ice via condensation freezing at -35 °C with no ice nucleation observed at -30 °C for wood burning particles. Photochemical aging did not affect the ice nucleation ability of the diesel and wood burning particles at the three different temperatures investigated but a broader range of temperatures below -30 °C need to be investigated in order to draw an overall conclusion on the effect of photochemical aging on deposition/condensation ice nucleation across the entire temperature range relevant to cold clouds.

  15. Effect of photochemical aging on the ice nucleation properties of diesel and wood burning particles

    Directory of Open Access Journals (Sweden)

    C. Chou

    2012-06-01

    Full Text Available A measurement campaign (IMBALANCE was conducted in 2009 and aimed at characterizing the physical and chemical properties of freshly emitted and photochemically aged combustion particles emitted from a log wood burner and diesel vehicles: a EURO3 Opel Astra with a diesel oxidation catalyst (DOC but no particle filter and a EURO2 Volkswagen Transporter TDI Syncro with no emission after-treatment. Ice nucleation experiments in the deposition and condensation freezing modes were conducted with the Portable Ice Nucleation Chamber (PINC at three nominal temperatures, −30 °C, −35 °C and −40 °C. Freshly emitted diesel particles showed ice formation only at −40 °C in the deposition mode at 137% relative humidity with respect to ice (RHi and 92% relative humidity with respect to water (RHw, and photochemical aging did not play a role in modifying their ice nucleation behavior. Only one diesel experiment where α-pinene was added, showed an ice nucleation enhancement after the aging at −35 °C. Wood burning particles also act as ice nuclei (IN at −40 °C in the deposition mode at the same conditions as for diesel particles and photochemical aging did also not alter the ice formation properties of the wood burning particles. Unlike diesel particles, wood burning particles form ice via condensation freezing at −35 °C with no ice nucleation observed at −30 °C for wood burning particles. Photochemical aging did not affect the ice nucleation ability of the diesel and wood burning particles at the three different temperatures investigated but a broader range of temperatures below −30 °C need to be investigated in order to draw an overall conclusion on the effect of photochemical aging on deposition/condensation ice nucleation across the entire temperature range relevant to cold clouds.

  16. Effect of photochemical ageing on the ice nucleation properties of diesel and wood burning particles

    Directory of Open Access Journals (Sweden)

    C. Chou

    2013-01-01

    Full Text Available A measurement campaign (IMBALANCE conducted in 2009 was aimed at characterizing the physical and chemical properties of freshly emitted and photochemically aged combustion particles emitted from a log wood burner and diesel vehicles: a EURO3 Opel Astra with a diesel oxidation catalyst (DOC but no particle filter and a EURO2 Volkswagen Transporter TDI Syncro without emission aftertreatment. Ice nucleation experiments in the deposition and condensation freezing modes were conducted with the Portable Ice Nucleation Chamber (PINC at three nominal temperatures, −30 °C, −35 °C and −40 °C. Freshly emitted diesel particles showed ice formation only at −40 °C in the deposition mode at 137% relative humidity with respect to ice (RHi and 92% relative humidity with respect to water (RHw, and photochemical ageing did not play a role in modifying their ice nucleation behaviour. Only one diesel experiment where α-pinene was added for the ageing process, showed an ice nucleation enhancement at −35 °C. Wood burning particles also act as ice nuclei (IN at −40 °C in the deposition mode at the same conditions as for diesel particles and photochemical ageing also did not alter the ice formation properties of the wood burning particles. Unlike diesel particles, wood burning particles form ice via condensation freezing at −35 °C whereas no ice nucleation was observed at −30 °C. Photochemical ageing did not affect the ice nucleation ability of the diesel and wood burning particles at the three different temperatures investigated but a broader range of temperatures below −40 °C need to be investigated in order to draw an overall conclusion on the effect of photochemical ageing on deposition/condensation ice nucleation across the entire temperature range relevant to cold clouds.

  17. Probing into the aging dynamics of biomass burning aerosol by using satellite measurements of aerosol optical depth and carbon monoxide

    Science.gov (United States)

    Konovalov, Igor B.; Beekmann, Matthias; Berezin, Evgeny V.; Formenti, Paola; Andreae, Meinrat O.

    2017-04-01

    Carbonaceous aerosol released into the atmosphere from open biomass burning (BB) is known to undergo considerable chemical and physical transformations (aging). However, there is substantial controversy about the nature and observable effects of these transformations. A shortage of consistent observational evidence on BB aerosol aging processes under different environmental conditions and at various temporal scales hinders development of their adequate representations in chemistry transport models (CTMs). In this study, we obtain insights into the BB aerosol dynamics by using available satellite measurements of aerosol optical depth (AOD) and carbon monoxide (CO). The basic concept of our method is to consider AOD as a function of the BB aerosol photochemical age (that is, the time period characterizing the exposure of BB aerosol emissions to atmospheric oxidation reactions) predicted by means of model tracers. We evaluate the AOD enhancement ratio (ER) defined as the ratio of optical depth of actual BB aerosol with respect to that of a modeled aerosol tracer that is assumed to originate from the same fires as the real BB aerosol but that is not affected by any aging processes. To limit possible effects of model transport errors, the AOD measurements are normalized to CO column amounts that are also retrieved from satellite measurements. The method is applied to the analysis of the meso- and synoptic-scale evolution of aerosol in smoke plumes from major wildfires that occurred in Siberia in summer 2012. AOD and CO retrievals from MODIS and IASI measurements, respectively, are used in combination with simulations performed with the CHIMERE CTM. The analysis indicates that aging processes strongly affected the evolution of BB aerosol in the situation considered, especially in dense plumes (with spatial average PM2. 5 concentration exceeding 100 µg m-3). For such plumes, the ER is found to increase almost 2-fold on the scale of ˜ 10 h of daytime aerosol evolution

  18. Shock tube measurements of growth constants in the branched chain formaldehyde-carbon monoxide-oxygen system

    Science.gov (United States)

    Brabbs, T. A.; Brokaw, R. S.

    1982-01-01

    Exponential free radical growth constants were measured for formaldehyde carbon monoxide-oxygen systems by monitoring the growth of oxygen atom concentration as manifested by CO flame band emission. Data were obtained over the temperature range of 1200 to 2000 K. The data were analyzed using a formaldehyde oxidation mechanism involving 12 elementary reaction steps. The computed growth constants are roughly in accord with experimental values, but are much more temperature dependent. The data was also analyzed assuming formaldehyde is rapidly decomposed to carbon monoxide and hydrogen. Growth constants computed for the resulting carbon monoxide hydrogen oxygen mixtures have a temperature dependence similar to experiments; however, for most mixtures, the computed growth constants were larger than experimental values.

  19. Thermo-cleavable polymers: Materials with enhanced photochemical stability

    DEFF Research Database (Denmark)

    Manceau, Matthieu; Petersen, Martin Helgesen; Krebs, Frederik C

    2010-01-01

    Photochemical stability of three thermo-cleavable polymers was investigated as thin films under atmospheric conditions. A significant increase in lifetime was observed once the side-chain was cleaved emphasizing the detrimental effect of solubilizing groups on the photochemical stability of conju......Photochemical stability of three thermo-cleavable polymers was investigated as thin films under atmospheric conditions. A significant increase in lifetime was observed once the side-chain was cleaved emphasizing the detrimental effect of solubilizing groups on the photochemical stability...... of conjugated polymers. In addition to their ease of processing, thermo-cleavable polymers thus also offer a greater intrinsic stability under illumination....

  20. Methane on Mars: Thermodynamic Equilibrium and Photochemical Calculations

    Science.gov (United States)

    Levine, J. S.; Summers, M. E.; Ewell, M.

    2010-01-01

    The detection of methane (CH4) in the atmosphere of Mars by Mars Express and Earth-based spectroscopy is very surprising, very puzzling, and very intriguing. On Earth, about 90% of atmospheric ozone is produced by living systems. A major question concerning methane on Mars is its origin - biological or geological. Thermodynamic equilibrium calculations indicated that methane cannot be produced by atmospheric chemical/photochemical reactions. Thermodynamic equilibrium calculations for three gases, methane, ammonia (NH3) and nitrous oxide (N2O) in the Earth s atmosphere are summarized in Table 1. The calculations indicate that these three gases should not exist in the Earth s atmosphere. Yet they do, with methane, ammonia and nitrous oxide enhanced 139, 50 and 12 orders of magnitude above their calculated thermodynamic equilibrium concentration due to the impact of life! Thermodynamic equilibrium calculations have been performed for the same three gases in the atmosphere of Mars based on the assumed composition of the Mars atmosphere shown in Table 2. The calculated thermodynamic equilibrium concentrations of the same three gases in the atmosphere of Mars is shown in Table 3. Clearly, based on thermodynamic equilibrium calculations, methane should not be present in the atmosphere of Mars, but it is in concentrations approaching 30 ppbv from three distinct regions on Mars.

  1. Remotely sensing the photochemical reflectance index, PRI

    Science.gov (United States)

    Vanderbilt, Vern; Daughtry, Craig; Dahlgren, Robert

    2015-09-01

    In remote sensing, the Photochemical Reflectance Index (PRI) provides insight into physiological processes occurring inside leaves in a plant stand. Developed by1,2, PRI evolved from laboratory reflectance measurements of individual leaves. Yet in a remotely sensed image, a pixel measurement may include light from both reflecting and transmitting leaves. We compared values of PRI based upon polarized reflectance and transmittance measurements of water and nutrient stressed leaves. Our results show the polarized leaf surface reflection should be removed when calculating PRI and that the leaf physiology information is in leaf interior reflectance, not leaf transmittance.

  2. Photochemical synthesis of biomolecules under anoxic conditions

    Science.gov (United States)

    Folsome, C.; Brittain, A.; Zelko, M.

    1983-01-01

    The long-wavelength UV anoxic photosynthesis of uracil, various sugars (including deoxyribose and glycoaldehyde), amino acids, and other organic photoproducts is reported. The reactions were conducted in a mixture of water, calcium carbonate, hydrazine, and formaldehyde which were subjected to 24 hr or 72 hr radiation. Product yields were greatest when the hydrazine/formaldehyde ratio was one, and when the reactant concentrations were low. These data suggest that organic products can be formed in variety from those amounts of formaldehyde and hydazine precursors which are themselves formed under anoxic UV photochemical conditions.

  3. Enantioselectivity of Photochemical Reactions within Polymer Microcapsules

    Institute of Scientific and Technical Information of China (English)

    MA,Lei; WU,Li-Zhu; ZHANG,Li-Ping; TUNG,Chen-Ho

    2003-01-01

    Polymer microcapsule was employed as a reaction medium to achieve enantioselectivity in photochemical reduction of phenyl cyclohexyl ketone and photoelectrocyclization of tropolone methyl ether unader the influence of various chiral inductors. In all cases,low but evident enantioselectivity was observed. The poor enantioselectivity is probably due to the facts that not all the capsules include simultaneously both the chiral inductor and the reactant molecules, and the wall of the microcapsule is not rigid enough tohold the reactant and the chiral inductor moleculesin close contact.

  4. Using 18O as a Tracer of Oxygen in the Photochemical Alteration of Dissolved Organic Matter

    Science.gov (United States)

    Davis, J. A.; Stubbins, A.; Helms, J.; Dias, R. F.; Mopper, K.

    2006-12-01

    The biogeochemical cycling of dissolved organic matter (DOM) in natural waters is affected by numerous processes, including photochemical alteration. Photochemical processes result in the net oxidation and mineralization of DOM concomitant with dissolved oxygen consumption and production of dissolved inorganic carbon (DIC; principally CO2). The photochemical oxygen budget is not well constrained while DIC production accounts for nearly all the dissolved oxygen consumed, conflicting data suggests that more than half of the oxygen consumed is required to account for observed DOM oxidation and hydrogen peroxide production. An alternate source of oxygen is required to balance this budget; water itself may provide the answer. In order to determine the source of oxygen, a number of time series irradiations were performed using Great Dismal Swamp water (southeast Virginia) with 18O enrichments as either dissolved oxygen or water. Early results, upon irradiation in a UV solar simulator, show significant incorporation of 18O-enriched oxygen into high molecular weight (HMW) DOM from both sources. While the majority of the incorporated oxygen originated from the dissolved oxygen, at least 5 percent originated from water. Data will be presented showing the rate and degree of incorporation of 18O-enriched oxygen from both sources as well as the production of 18O-enriched carbon dioxide. The movement of 18O label will be discussed in relation to shifts in spectral qualities, including photobleaching and spectral slope, of the irradiated samples and selective incorporation as detailed by FT-ICRMS.

  5. Compact Instrument for Measurement of Atmospheric Carbon Monoxide Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Southwest Sciences proposed the development of a rugged, compact, and automated instrument for the high sensitivity measurement of tropospheric carbon monoxide...

  6. Oxidation-reduction catalyst and its process of use

    Science.gov (United States)

    Jordan, Jeffrey D. (Inventor); Watkins, Anthony Neal (Inventor); Schryer, Jacqueline L. (Inventor); Oglesby, Donald M. (Inventor)

    2008-01-01

    This invention relates generally to a ruthenium stabilized oxidation-reduction catalyst useful for oxidizing carbon monoxide, and volatile organic compounds, and reducing nitrogen oxide species in oxidizing environments, substantially without the formation of toxic and volatile ruthenium oxide species upon said oxidizing environment being at high temperatures.

  7. Mass psychogenic systemic illness in school children in relation to the Tokyo photochemical smog

    Energy Technology Data Exchange (ETDEWEB)

    Araki, S.; Honma, T.

    1986-05-01

    To clarify the pathogenic mechanism of epidemics with acute systemic neurobehavioral illness associated with photochemical air pollution in Japan, we re-examined our past records in sixteen junior high school children, and compared them with major epidemics that occurred in 1970-1972 during which time Japanese society faced a new and unusual type of air pollution (Tokyo smog). Dysfunction of alveolar-arterial gas exchange, together with respiratory alkalosis, was newly found in these children, who suffered from chest discomfort, ocular irritation, emotional distress, tetany, and unconsciousness. It was concluded that anxiety reaction, precipitated by the physical effects of photochemical oxidants and athletic performance, possibly led to many outbreaks of mass psychogenic systemic illness (hyperventilation syndrome) among school children.

  8. FTIR and DSC studies of the thermal and photochemical stability of Balanites aegyptiaca oil (Toogga oil).

    Science.gov (United States)

    Gardette, Jean-Luc; Baba, Mohamed

    2013-01-01

    The oil extracted from the bean of Balanites aegyptiaca was characterized, and its photochemical and thermal stabilization were evaluated. The chemical composition was determined using gas chromatography (GC), revealing that the oil is very rich in unsaturated fatty acids (72% omega-6 and omega-9). The photochemical stability was assessed by subjecting it to artificially accelerated photo-aging and then examining the changes using infrared spectroscopy. The thermal stability was studied at six different temperatures ranging from 130 to 200°C and monitored in situ by differential scanning calorimetry (DSC). The kinetic parameters (EA and k) describing the thermal degradation of this oil were calculated. It has been shown that the antioxidants present in the oil delay the oxidation process (induction period). The degradation of the Toogga oil was compared with that of oleic and linoleic fatty acids. In addition, the degradation of the Toogga oil extracted with hexane was compared to that of the neat oil.

  9. Electricity generation from carbon monoxide and syngas in a microbial fuel cell.

    Science.gov (United States)

    Hussain, Abid; Guiot, Serge R; Mehta, Punita; Raghavan, Vijaya; Tartakovsky, Boris

    2011-05-01

    Electricity generation in microbial fuel cells (MFCs) has been a subject of significant research efforts. MFCs employ the ability of electricigenic bacteria to oxidize organic substrates using an electrode as an electron acceptor. While MFC application for electricity production from a variety of organic sources has been demonstrated, very little research on electricity production from carbon monoxide and synthesis gas (syngas) in an MFC has been reported. Although most of the syngas today is produced from non-renewable sources, syngas production from renewable biomass or poorly degradable organic matter makes energy generation from syngas a sustainable process, which combines energy production with the reprocessing of solid wastes. An MFC-based process of syngas conversion to electricity might offer a number of advantages such as high Coulombic efficiency and biocatalytic activity in the presence of carbon monoxide and sulfur components. This paper presents a discussion on microorganisms and reactor designs that can be used for operating an MFC on syngas.

  10. The Effect of Water Vapor on Flame Velocity in Equivalent Carbon Monoxide and Oxygen Mixtures

    Science.gov (United States)

    Fiock, Ernest F; King, H Kendall

    1936-01-01

    This report presents the results of an investigation to study the effect of water vapor upon the spatial speed of flame in equivalent mixtures of carbon monoxide and oxygen at various total pressures from 100 to 780 mm.hg. These results show that, within this pressure range, an increase in flame speed is produced by increasing the mole fraction of water vapor at least as far as saturation at 25 degrees c., and that the rate of this increase is greater the higher the pressure. It is evident that water vapor plays an important part in the explosive oxidation of carbon monoxide; the need for further experimental evidence as to the nature of its action is indicated.

  11. Photochemical processes for atrazine degradation: methodological approach.

    Science.gov (United States)

    Héquet, V; Gonzalez, C; Le Cloirec, P

    2001-12-01

    Numerous studies have been carried out on s-triazines, and more specifically on atrazine, with the long-term objective of resolving the problems caused by these herbicides: removing them from drinking water. However, applications have remained too limited. So far, processes based on photochemical degradation have been little implemented. We, therefore, investigated the development of photochemical processes, emphasizing their capacity to degrade triazine by photolytic and photocatalytic mode. The study sought to assess the performance of these ssstems. Experiments ts showed that according to a medium pressure mercury source (UV-Vis irradiation), the photolytic degradation of atrazine was very efficient, with a best atrazine degradation half-life shorter that 5 min. The main degradation pathway was deshalogenation. The photocatalytic degradation of atrazine under irradiation over 290 nm in the presence of titanium dioxide was shown to be efficient too, with a half-life of about 20 min. In this case an experimental design was conducted so as to assess the influence of various parameters: pH, water medium, and amount of catalyst. There has been observational evidence for the efficiency of the processes investigated here and for potential technological developments as regards drinking water treatment.

  12. Photochemical tissue bonding with chitosan adhesive films

    Directory of Open Access Journals (Sweden)

    Piller Sabine C

    2010-09-01

    Full Text Available Abstract Background Photochemical tissue bonding (PTB is a promising sutureless technique for tissue repair. PTB is often achieved by applying a solution of rose bengal (RB between two tissue edges, which are irradiated by a green laser to crosslink collagen fibers with minimal heat production. In this study, RB has been incorporated in chitosan films to create a novel tissue adhesive that is laser-activated. Methods Adhesive films, based on chitosan and containing ~0.1 wt% RB were manufactured and bonded to calf intestine by a solid state laser (λ = 532 nm, Fluence~110 J/cm2, spot size~0.5 cm. A single-column tensiometer, interfaced with a personal computer, tested the bonding strength. K-type thermocouples recorded the temperature (T at the adhesive-tissue interface during laser irradiation. Human fibroblasts were also seeded on the adhesive and cultured for 48 hours to assess cell growth. Results The RB-chitosan adhesive bonded firmly to the intestine with adhesion strength of 15 ± 2 kPa, (n = 31. The adhesion strength dropped to 0.5 ± 0.1 (n = 8 kPa when the laser was not applied to the adhesive. The average temperature of the adhesive increased from 26°C to 32°C during laser exposure. Fibroblasts grew confluent on the adhesive without morphological changes. Conclusion A new biocompatible chitosan adhesive has been developed that bonds photochemically to tissue with minimal temperature increase.

  13. Chitosan Adhesive Films for Photochemical Tissue Bonding

    Science.gov (United States)

    Lauto, Antonio; Mawad, Damia; Barton, Matthew; Piller, Sabine C.; Longo, Leonardo

    2011-08-01

    Photochemical tissue bonding (PTB) is a promising sutureless technique for tissue repair. PTB is often achieved by applying a solution of rose bengal (RB) between two tissue edges, which are irradiated by a green laser to crosslink collagen fibers with minimal heat production. In this study, RB has been incorporated in chitosan films to create a novel tissue adhesive that is laser-activated. Materials and Methods. Adhesive films, based on chitosan and containing ˜0.1wt% RB were manufactured and bonded to calf intestine by a solid state laser (wavelength = 532 nm, Fluence ˜110 J/cm2, spot size ˜5 mm). A single-column tensiometer, interfaced with a personal computer, tested the bonding strength. K-type thermocouples recorded the temperature (T) at the adhesive-tissue interface during laser irradiation. Human fibroblasts were also seeded on the adhesive and cultured for 48 hours to assess cell growth. Results and Conclusion. The RB-chitosan adhesive bonded firmly to the intestine (15±2 kPa, n = 31). The adhesion strength dropped to 0.5±0.1 kPa (n = 8) when the laser was not applied to the adhesive. The average temperature of the adhesive increased from 26 °C to 32 °C during laser exposure. Fibroblasts grew confluent on the adhesive without morphological changes. A new biocompatible chitosan adhesive has been developed that bonds photochemically to tissue with minimal temperature increase.

  14. Photochemical production of carbon disulphide in seawater

    Science.gov (United States)

    Xie, Huixiang; Moore, Robert M.; Miller, William L.

    1998-03-01

    It is generally accepted that the ocean is an important source for atmospheric CS2, which makes a major contribution to the formation of COS in the atmosphere. The processes producing CS2 in seawater, however, are essentially unknown. We report for the first time to our knowledge that marine photochemical reactions are identified as a significant source for oceanic CS2. Apparent quantum yield spectra of CS2 production were obtained using water samples collected in the northeast Atlantic. Results indicate that it is mainly UV solar radiation (290-340 nm) which is responsible for CS2 photoproduction. The photoproduction rate of CS2 is positively correlated with absorbance at 350 nm, suggesting that the reactions are mediated by chromophoric dissolved organic matter (CDOM). Laboratory irradiations have confirmed that cysteine and cystine are efficient precursors of CS2 and that OH radicals are likely to be important intermediates. Both the field survey and laboratory work point to similar mechanisms for photochemical production of CS2 and COS in marine waters. A CS2 production rate of 0.49 Tg yr-1 for the world oceans has been estimated using the quantum yield spectra from this work and the sea surface light field provided by Leifer [1988]. This estimate is of the same order of magnitude as the present estimate of the CS2 flux from the ocean to the atmosphere based on surface saturation and wind speed.

  15. Photochemical tissue bonding with chitosan adhesive films.

    Science.gov (United States)

    Lauto, Antonio; Mawad, Damia; Barton, Matthew; Gupta, Abhishek; Piller, Sabine C; Hook, James

    2010-09-08

    Photochemical tissue bonding (PTB) is a promising sutureless technique for tissue repair. PTB is often achieved by applying a solution of rose bengal (RB) between two tissue edges, which are irradiated by a green laser to crosslink collagen fibers with minimal heat production. In this study, RB has been incorporated in chitosan films to create a novel tissue adhesive that is laser-activated. Adhesive films, based on chitosan and containing ~0.1 wt% RB were manufactured and bonded to calf intestine by a solid state laser (λ = 532 nm, Fluence~110 J/cm2, spot size~0.5 cm). A single-column tensiometer, interfaced with a personal computer, tested the bonding strength. K-type thermocouples recorded the temperature (T) at the adhesive-tissue interface during laser irradiation. Human fibroblasts were also seeded on the adhesive and cultured for 48 hours to assess cell growth. The RB-chitosan adhesive bonded firmly to the intestine with adhesion strength of 15 ± 2 kPa, (n = 31). The adhesion strength dropped to 0.5 ± 0.1 (n = 8) kPa when the laser was not applied to the adhesive. The average temperature of the adhesive increased from 26°C to 32°C during laser exposure. Fibroblasts grew confluent on the adhesive without morphological changes. A new biocompatible chitosan adhesive has been developed that bonds photochemically to tissue with minimal temperature increase.

  16. Photochemical aerosols in warm exoplanetary atmospheres

    Science.gov (United States)

    Imanaka, Hiroshi; Smith, Mark A.; McKay, Christopher P.; Cruikshank, Dale P.; Marley, Mark S.

    2016-10-01

    Recent transit observations of exoplanets have demonstrated the possibility of a wide prevalence of haze/cloud layers at high altitudes. Hydrocarbon photochemical haze could be the candidate for such haze particles on warm sub-Neptunes, but the lack of evidence for methane poses a puzzle for such hydrocarbon photochemical haze. The CH4/CO ratios in planetary atmospheres vary substantially from their temperature and dynamics. We have conducted a series of laboratory simulations to investigate how atmospheric compositions, specifically CH4/CO ratios, affect the haze production rates and their optical properties. The mass production rates in the H2-CH4-CO gas mixtures are rather insensitive to the CH4/CO ratios larger than at 0.3. Significant formation of solid material is observed in a H2-CO gas mixture even without CH4. The complex refractive indices of the aerosol analogue from the H2-CO gas mixture show strong absorption at the visible/near-IR wavelengths. These experimental facts imply that substantial carbonaceous aerosols may be generated in warm H2-CO-CH4 exoplanetary atmospheres, and that it might be responsible for the observed dark albedos at the visible wavelengths.

  17. Analysis of Carbon Monoxide in Blood

    Science.gov (United States)

    Huddle, Benjamin P.; Stephens, Joseph C.

    2003-04-01

    Forensic tests used to perform the qualitative and quantitative analyses of carbon monoxide in blood are described. The qualitative test uses the diffusion of CO, which is released from blood by reaction with H2SO4, into a PdCl2 solution in a Conway cell and the resultant formation of a palladium mirror. The quantitative analysis is based on the absorption of visible light by carboxyhemoglobin at 541 nm and reduced hemoglobin at 555 nm. Both procedures are suitable for undergraduate chemistry experiments.

  18. Evaluation of the photochemical production of hydrogen from solar energy

    Energy Technology Data Exchange (ETDEWEB)

    Heppert, J. A.

    1977-08-09

    The potential for utilizing solar energy through photochemical storage were investigated. Both water and nitrosyl chloride systems are examined. A comprehensive review of the literature led to the conclusion that many major questions must be answered before photochemical energy storage becomes a viable alternate means of exploiting solar energy.

  19. 40 CFR 52.777 - Control strategy: photochemical oxidants (hydrocarbons).

    Science.gov (United States)

    2010-07-01

    ... from mobile sources and demonstrating that no increase in emissions would take place. Indiana satisfied... control technology (RACT), new source review (NSR), vehicle inspection/maintenance (I/M), and general... (NOX) reasonably available control technology (RACT) requirements under section 182(f) of the Clean...

  20. Laboratory investigations of the photochemical decay of alkylbromides trapped in ice

    Science.gov (United States)

    Schrems, Otto; Okaikwei, Bismark; Bluszcz, Thaddäus

    2014-05-01

    Photochemical reactions of atmospheric trace gases taking place at the surface of atmospheric ice particles and in bulk ice are important in tropospheric chemistry but also in polar and alpine snowpack chemistry. Consequently, the understanding of the uptake und incorporation of tropospheric trace gases in water ice as well as their interactions with water molecules is very important for the understanding of processes which occur in ice particles and at the air/ice interface. Reactive atmospheric trace gases trapped in ice are subject of photochemical reactions when irradiated with solar UV radiation. Among such compounds bromine species are highly interesting due to their potential of depleting ozone both in the stratosphere and troposphere. Methyl bromide (CH3Br) is the largest bromine carrier to the stratosphere. It has both natural and anthropogenic sources. In this contribution we will present the results of our laboratory studies of alkyl bromides (methyl bromide (CH3Br), methyl dibromide (CH2Br2), n-propyl bromide (C3H7Br), 1,2-dibromoethane C2H4Br2)), trapped in water ice. We have simulated the UV photochemistry of these brominated alkanes isolated in ice films kept at 16 K and for comparison in solid argon matrices. The photoproducts formed in the ice have been identified by means of FTIR spectroscopy. Reflection absorption infrared spectroscopy (RAIRS) is especially useful to study nascent ice surfaces, kinetics of adsorption/decomposition, and heterogeneous catalysis. Among the observed photoproducts we could identify carbon monoxide and carbon dioxide for each alkyl bromide studied. The photoproduct HBr is dissociated in the bulk ice. Based on the experimental observations possible reaction mechanisms will be discussed.

  1. Low concentration of exogenous carbon monoxide protects mammalian cells against proliferation induced by radiation-induced bystander effect

    Energy Technology Data Exchange (ETDEWEB)

    Tong, Liping [Center of Medical Physics and Technology, Hefei Institutes of Physical Science, Chinese Academy of Sciences, Hefei 230031 (China); Yu, K.N. [Department of Physics and Materials Science, City University of Hong Kong, Tat Chee Avenue, Kowloon Tong (Hong Kong); Center of Medical Physics and Technology, Hefei Institutes of Physical Science, Chinese Academy of Sciences, Hefei 230031 (China); Bao, Lingzhi; Wu, Wenqing; Wang, Hongzhi [Center of Medical Physics and Technology, Hefei Institutes of Physical Science, Chinese Academy of Sciences, Hefei 230031 (China); Han, Wei, E-mail: hanw@hfcas.cn [Center of Medical Physics and Technology, Hefei Institutes of Physical Science, Chinese Academy of Sciences, Hefei 230031 (China)

    2014-01-15

    Highlights: • We show the possibility of modulate proliferation induced by radiation-induced bystander effect with low concentration carbon monoxide. • Carbon monoxide inhibited proliferation via modulating the transforming growth factor β1 (TGF-β1)/nitric oxide (NO) signaling pathway. • Exogenous carbon monoxide has potential application in clinical radiotherapy. - Abstract: Radiation-induced bystander effect (RIBE) has been proposed to have tight relationship with the irradiation-caused secondary cancers beyond the irradiation-treated area after radiotherapy. Our previous studies demonstrated a protective effect of low concentration carbon monoxide (CO) on the genotoxicity of RIBE after α-particle irradiation. In the present work, a significant inhibitory effect of low-dose exogenous CO, generated by tricarbonyldichlororuthenium (II) dimer [CO-releasing molecule (CORM-2)], on both RIBE-induced proliferation and chromosome aberration was observed. Further studies on the mechanism revealed that the transforming growth factor β1/nitric oxide (NO) signaling pathway, which mediated RIBE signaling transduction, could be modulated by CO involved in the protective effects. Considering the potential of exogenous CO in clinical applications and its protective effect on RIBE, the present work aims to provide a foundation for potential application of CO in radiotherapy.

  2. [Carbon monoxide poisoning by a heating system].

    Science.gov (United States)

    Dietz, Eric; Gehl, Axel; Friedrich, Peter; Kappus, Stefan; Petter, Franz; Maurer, Klaus; Püschel, Klaus

    2016-01-01

    A case of accidental carbon monoxide poisoning in several occupants of two neighboring residential buildings in Hamburg-Harburg (Germany) caused by a defective gas central heating system is described. Because of leaks in one of the residential buildings and the directly adjacent wall of the neighboring house, the gas could spread and accumulated in both residential buildings, which resulted in a highly dangerous situation. Exposure to the toxic gas caused mild to severe intoxication in 15 persons. Three victims died still at the site of the accident. Measures to protect the occupants were taken only with a great delay. As symptoms were unspecific, it was not realized that the various alarms given by persons involved in the accident were related to the same cause. In order to take appropriate measures in time it is indispensible to recognize, assess and check potential risks, which can be done by using carbon monoxide warning devices and performing immediate COHb measurements with special pulse oximeters on site. Moreover, the COHb content in the blood should be routinely determined in all patients admitted to an emergency department with unspecific symptoms.

  3. Observations of iodine monoxide columns from satellite

    Directory of Open Access Journals (Sweden)

    A. Schönhardt

    2008-02-01

    Full Text Available Iodine species in the troposphere are linked to ozone depletion and new particle formation. In this study, a full year of iodine monoxide (IO columns retrieved from measurements of the SCIAMACHY satellite instrument is presented, coupled with a discussion of their uncertainties and the detection limits. The largest amounts of IO are found near springtime in the Antarctic. A seasonal variation of iodine monoxide in Antarctica is revealed with high values in springtime, slightly less IO in the summer period and again larger amounts in autumn. In winter, no elevated IO levels are found in the areas accessible to satellite measurements. This seasonal cycle is in good agreement with recent ground-based measurements in Antarctica. In the Arctic region, no elevated IO levels were found in the period analysed. This implies that different conditions with respect to iodine release exist in the two Polar Regions. To investigate possible release mechanisms, comparisons of IO columns with those of tropospheric BrO, and ice coverage are described and discussed. Some parallels and interesting differences between IO and BrO temporal and spatial distributions are identified. Overall, the large spatial coverage of satellite retrieved IO data and the availability of a long-term dataset provide new insight about the abundances and distributions of iodine compounds in the troposphere.

  4. Fatal carbon monoxide intoxication after acetylene gas welding of pipes.

    Science.gov (United States)

    Antonsson, Ann-Beth; Christensson, Bengt; Berge, Johan; Sjögren, Bengt

    2013-06-01

    Acetylene gas welding of district heating pipes can result in exposure to high concentrations of carbon monoxide. A fatal case due to intoxication is described. Measurements of carbon monoxide revealed high levels when gas welding a pipe with closed ends. This fatality and these measurements highlight a new hazard, which must be promptly prevented.

  5. Real World of Industrial Chemistry: Organic Chemicals from Carbon Monoxide.

    Science.gov (United States)

    Kolb, Kenneth E.; Kolb, Doris

    1983-01-01

    Carbon Monoxide obtained from coal may serve as the source for a wide variety of organic compounds. Several of these compounds are discussed, including phosgene, benzaldehyde, methanol, formic acid and its derivatives, oxo aldehydes, acrylic acids, and others. Commercial reactions of carbon monoxide are highlighted in a table. (JN)

  6. Plasmonic antenna effects on photochemical reactions.

    Science.gov (United States)

    Gao, Shuyan; Ueno, Kosei; Misawa, Hiroaki

    2011-04-19

    Efficient solar energy conversion has been vigorously pursued since the 1970s, but its large-scale implementation hinges on the availability of high-efficiency modules. For maximum efficiency, it is important to absorb most of the incoming radiation, which necessitates both efficient photoexcitation and minimal electron-hole recombination. To date, researchers have primarily focused on the latter difficulty: finding a strategy to effectively separate photoinduced electrons and holes. Very few reports have been devoted to broadband sunlight absorption and photoexcitation. However, the currently available photovoltaic cells, such as amorphous silicon, and even single-crystal silicon and sensitized solar cells, cannot respond to the wide range of the solar spectrum. The photoelectric conversion characteristics of solar cells generally decrease in the infrared wavelength range. Thus, the fraction of the solar spectrum absorbed is relatively poor. In addition, the large mismatch between the diffraction limit of light and the absorption cross-section makes the probability of interactions between photons and cell materials quite low, which greatly limits photoexcitation efficiency. Therefore, there is a pressing need for research aimed at finding conditions that lead to highly efficient photoexcitation over a wide spectrum of sunlight, particularly in the visible to near-infrared wavelengths. As characterized in the emerging field of plasmonics, metallic nanostructures are endowed with optical antenna effects. These plasmonic antenna effects provide a promising platform for artificially sidestepping the diffraction limit of light and strongly enhancing absorption cross-sections. Moreover, they can efficiently excite photochemical reactions between photons and molecules close to an optical antenna through the local field enhancement. This technology has the potential to induce highly efficient photoexcitation between photons and molecules over a wide spectrum of sunlight

  7. Mechanistic insights into chemical and photochemical transformations of bismuth vanadate photoanodes

    Science.gov (United States)

    Toma, Francesca M.; Cooper, Jason K.; Kunzelmann, Viktoria; McDowell, Matthew T.; Yu, Jie; Larson, David M.; Borys, Nicholas J.; Abelyan, Christine; Beeman, Jeffrey W.; Yu, Kin Man; Yang, Jinhui; Chen, Le; Shaner, Matthew R.; Spurgeon, Joshua; Houle, Frances A.; Persson, Kristin A.; Sharp, Ian D.

    2016-07-01

    Artificial photosynthesis relies on the availability of semiconductors that are chemically stable and can efficiently capture solar energy. Although metal oxide semiconductors have been investigated for their promise to resist oxidative attack, materials in this class can suffer from chemical and photochemical instability. Here we present a methodology for evaluating corrosion mechanisms and apply it to bismuth vanadate, a state-of-the-art photoanode. Analysis of changing morphology and composition under solar water splitting conditions reveals chemical instabilities that are not predicted from thermodynamic considerations of stable solid oxide phases, as represented by the Pourbaix diagram for the system. Computational modelling indicates that photoexcited charge carriers accumulated at the surface destabilize the lattice, and that self-passivation by formation of a chemically stable surface phase is kinetically hindered. Although chemical stability of metal oxides cannot be assumed, insight into corrosion mechanisms aids development of protection strategies and discovery of semiconductors with improved stability.

  8. Mechanistic insights into chemical and photochemical transformations of bismuth vanadate photoanodes.

    Science.gov (United States)

    Toma, Francesca M; Cooper, Jason K; Kunzelmann, Viktoria; McDowell, Matthew T; Yu, Jie; Larson, David M; Borys, Nicholas J; Abelyan, Christine; Beeman, Jeffrey W; Yu, Kin Man; Yang, Jinhui; Chen, Le; Shaner, Matthew R; Spurgeon, Joshua; Houle, Frances A; Persson, Kristin A; Sharp, Ian D

    2016-07-05

    Artificial photosynthesis relies on the availability of semiconductors that are chemically stable and can efficiently capture solar energy. Although metal oxide semiconductors have been investigated for their promise to resist oxidative attack, materials in this class can suffer from chemical and photochemical instability. Here we present a methodology for evaluating corrosion mechanisms and apply it to bismuth vanadate, a state-of-the-art photoanode. Analysis of changing morphology and composition under solar water splitting conditions reveals chemical instabilities that are not predicted from thermodynamic considerations of stable solid oxide phases, as represented by the Pourbaix diagram for the system. Computational modelling indicates that photoexcited charge carriers accumulated at the surface destabilize the lattice, and that self-passivation by formation of a chemically stable surface phase is kinetically hindered. Although chemical stability of metal oxides cannot be assumed, insight into corrosion mechanisms aids development of protection strategies and discovery of semiconductors with improved stability.

  9. Search of medical literature for indoor carbon monoxide exposure

    Energy Technology Data Exchange (ETDEWEB)

    Brennan, T.; Ivanovich, M.

    1995-12-01

    This report documents a literature search on carbon monoxide. The search was limited to the medical and toxicological databases at the National Library of Medicine (MEDLARS). The databases searched were Medline, Toxline and TOXNET. Searches were performed using a variety of strategies. Combinations of the following keywords were used: carbon, monoxide, accidental, residential, occult, diagnosis, misdiagnosis, heating, furnace, and indoor. The literature was searched from 1966 to the present. Over 1000 references were identified and summarized using the following abbreviations: The major findings of the search are: (1) Acute and subacute carbon monoxide exposures result in a large number of symptoms affecting the brain, kidneys, respiratory system, retina, and motor functions. (2) Acute and subacute carbon monoxide (CO) poisonings have been misdiagnosed on many occasions. (3) Very few systematic investigations have been made into the frequency and consequences of carbon monoxide poisonings.

  10. Photochemically induced oscillations of aromatic pentazadienes

    Energy Technology Data Exchange (ETDEWEB)

    Kunz, T.; Hahn, C.; Wokaun, A. [Paul Scherrer Inst. (PSI), Villigen (Switzerland)

    1997-06-01

    Aromatic pentazadienes are used to enhance the laser induced ablation of standard polymers with low absorption in the UV. Therefore the photochemistry of substituted 1,5-diaryl-3-alkyl-1,4-pentazadiene monomers was studied with a pulsed excimer laser as irradiation source. The net photochemical reaction proceeds in an overall one-step pathway A{yields}B. Quantum yields for the laser decomposition were determined to be up to 10%. An oscillating behaviour of the absorption was found during the dark period following the irradiation. The temperature dependence of this dark reaction has been studied. An attempt to model this behaviour in terms of a non-linear coupling between heat released, heat transfer, and reaction kinetics will be described. (author) 4 figs., 4 refs.

  11. Photochemical stability of electrochromic polymers and devices

    DEFF Research Database (Denmark)

    Jensen, Jacob; Madsen, Morten Vesterager; Krebs, Frederik C

    2013-01-01

    The stability of fully printed flexible organic electrochromics based on 11 different conjugated polymers is explored from the fundamental chemical degradation level to the operational device level. The photochemical stability of the electrochromic polymers (ECPs) is studied enabling an analysis...... operations for many years under indoor conditions and for a few years under outside conditions. Finally, functioning electrochromic devices (ECDs) were made and the effect of illumination on the response time and optical contrast was established. This report shows that encapsulated electrochromic devices...... based on flexible barrier substrates exhibit increased stability and are indeed viable in devices such as shading elements, light management systems, displays with low switching speed requirements and signage. © 2013 The Royal Society of Chemistry....

  12. Fibre-optic photochemical stroke: generating and measuring photochemical changes inside the brain

    Science.gov (United States)

    Tsiminis, G.; Klarić, T. S.; Schartner, E. P.; Warren-Smith, S. C.; Lewis, M. D.; Koblar, S. A.; Monro, T. M.

    2014-05-01

    We report here on the development of a method to induce a stroke in a specific location within a mouse brain through the use of an optical fibre. By capturing the emitted fluorescence signal generated using the same fibre it is then possible to monitor photochemical changes within the brain in real-time, potentially reducing the requirement for post-operative histology to determine if a stroke has successfully been induced within the animal.

  13. Photochemical Wastewater Treatment for Potential Agricultural Use

    Directory of Open Access Journals (Sweden)

    Sandra García

    2014-12-01

    Full Text Available The urban wastewaters after advanced primary treatment (APT are again discharged into the river without any use. In the present research in a soilless culture system where maize seedlings were tested three different treatments were planted: 1. Obtained from the effluent water of an APT, 2. Photochemically treated wastewater (PCT and 3. Urban water network (UW. A block randomly distributed design was tested, with five repetitions where the experimental unit was formed by a 36 cavities filled with Peat Moss and the useful plot was considered by 16 central plants for each experimental unit. Irrigations were scheduled since the first time of the planting, employed 27 mL/cavity. The removal of the organic contaminants present into the water was conducted by the employment of a Batch photoreactor, adapted with a recirculation system (UV/H2O2/O3, evaluated to determine UV-Vis spectra, pH, color and turbidity parameters initial and final samples. Measurements of height and percentage of germination in plants, where is determined that the seedlings irrigated with water PCT were reached the highest average compared to APT and UW irrigated; After the 50 cm growing plant, a determination of the presence of heavy metal, via atomic absorption method, were carried on analyzing the leaves, roots and stalks of the samples. Concluding that the presences of heavy metals into the APT were higher than PCT treatments, it can be an impediment for the normal growing of the plants. Therefore, the application of the photochemical treatment using (UV/H2O2/O3 system, represent a viable alternative for the wastewater treatment after the APT process to possible use of irrigation.

  14. Photochemical reactions among formaldehyde, chlorine, and nitrogen dioxide in air

    Energy Technology Data Exchange (ETDEWEB)

    Hanst, P.L.; Gay, B.W. Jr.

    1977-11-01

    Photochemical reactions among chlorine, nitrogen dioxide, and formaldehyde were studied, using parts-per-million concentrations in 1 atm of air. The reactant mixtures were irradiated by ultraviolet fluorescent lamps and simultaneously analyzed by the Fourier transform infrared technique by use of folded light paths up to 504 m. With an excess of NO/sub 2/ over Cl/sub 2/, the reaction products included O/sub 3/, CO, HNO/sub 3/,N/sub 2/O/sub 5/, HCl, and nitryl chloride (ClNO/sub 2/). When chlorine exceeded NO/sub 2/, the principal product was peroxy nitric acid (HOONO/sub 2/). Peroxy formyl nitrate, nitrous acid, and chlorine nitrate were not seen. The nitryl chloride was stable even with the ultraviolet lights on. The peroxy nitric acid disappeared from the cell with a half-life of about 10 min. Formyl radicals (HCO), unlike acetyl radicals, did not combine with O/sub 2/ and NO/sub 2/ by addition. HCO reacted with O/sub 2/ to yield CO and HO/sub 2/. The HO/sub 2/ will then add to NO/sub 2/ to yield HOONO/sub 2/. If NO is present, the HO/sub 2/ will prefer to react with it, oxidizing it to NO/sub 2/.

  15. Photochemical degradation of marbofloxacin and enrofloxacin in natural waters.

    Science.gov (United States)

    Sturini, Michela; Speltini, Andrea; Maraschi, Federica; Profumo, Antonella; Pretali, Luca; Fasani, Elisa; Albini, Angelo

    2010-06-15

    The photochemical fate of Marbofloxacin (MAR) and Enrofloxacin (ENR), two Fluoroquinolones (FQs) largely used as veterinary bactericides known to be present in surface waters, was investigated in aqueous solution. The degradation of these pollutants (5-50 microg L(-1) starting concentration) was complete in about 1 h by exposure to solar light (summer) and obeyed a first-order kinetics. The structure of the primary photoproducts was determined. Those from ENR arose through three paths, namely, oxidative degradation of the piperazine side-chain, reductive defluorination, and fluorine solvolysis. More heavily degraded products that had been previously reported were rationalized as secondary photoproducts from the present ones. As for MAR, this underwent homolytic cleavage of the tetrahydrooxadiazine moiety to give two quinolinols. All of the primary products were themselves degraded in about 1 h. The photoreactions rates were scarcely affected by Ca(2+) (200 mg L(-1)), Mg(2+) (30 mg L(-1)), Cl(-) (30 mg L(-1)), and humic acid (1 mg L(-1)), but increased in the presence of phosphate (20 mg L(-1)). The fastest degradation of ENR occurred at pH about 8 where the zwitterionic form was present, while in the case of MAR the cationic form was the most reactive.

  16. Atmospheric photochemical degradation of 1,4-unsaturated dicarbonyls

    Energy Technology Data Exchange (ETDEWEB)

    Liu, X.; Jeffries, H.E.; Sexton, K.G.

    1999-12-01

    To better understand fates of aromatics hydrocarbon species in the atmosphere, the authors have investigated the transformation chemistry of butenedial (CHOCH{double{underscore}bond}CHCHO), 4-oxo-2-pentenal (CH{sub 3}COCH{double{underscore}bond}CHCHO), and 3-hexene-2, 5-dione (CH{sub 3}COCH{double{underscore}bond}CHCOCH{sub 3}). These 1,4-unsaturated dicarbonyls are known to be products of aromatic photochemical oxidation. Both hydroxyl radical (OH) and ozone (O{sub 3}) initiated smog chamber experiments under atmospheric conditions were conducted in the University of North Carolina outdoor smog chamber. Carbonyl intermediates and products were measured using the O-(2,3,4,5,6-pentafluorobenzyl)hydroxylamine derivatization method followed by gas chromatography/ion trap mass spectrometry analysis. Carbonyl products detected and identified by comparison with standards in the OH-initiated photooxidation of butenedial include formaldehyde, acrolein, glycolaldehyde, glyoxal, and malonaldehyde (CHOCH{sub 2}CHO). For 4-oxo-2-pentenal, the carbonyl products were formaldehyde, methyl vinyl ketone, glycolaldehyde, hydroxyacetone, glyoxal, methylglyoxal, and malonaldehyde. for 3-hexene-2,5-dione the products were formaldehyde, acetaldehyde, acetone, hydroxyacetone, and methylglyoxal. Carbonyl products detected in the P{sub 3}-initiated experiments with cyclohexane as the OH scavenger were formaldehyde and glyoxal in butenedial; formaldehyde, glyoxal, methyl-glyoxal, and malonaldehyde in 4-oxo-2-pentenal; and formaldehyde and methylglyoxal in 3-hexene-2,5-dione.

  17. A fresh look at the evolution and diversification of photochemical reaction centers.

    Science.gov (United States)

    Cardona, Tanai

    2015-10-01

    In this review, I reexamine the origin and diversification of photochemical reaction centers based on the known phylogenetic relations of the core subunits, and with the aid of sequence and structural alignments. I show, for example, that the protein folds at the C-terminus of the D1 and D2 subunits of Photosystem II, which are essential for the coordination of the water-oxidizing complex, were already in place in the most ancestral Type II reaction center subunit. I then evaluate the evolution of reaction centers in the context of the rise and expansion of the different groups of bacteria based on recent large-scale phylogenetic analyses. I find that the Heliobacteriaceae family of Firmicutes appears to be the earliest branching of the known groups of phototrophic bacteria; however, the origin of photochemical reaction centers and chlorophyll synthesis cannot be placed in this group. Moreover, it becomes evident that the Acidobacteria and the Proteobacteria shared a more recent common phototrophic ancestor, and this is also likely for the Chloroflexi and the Cyanobacteria. Finally, I argue that the discrepancies among the phylogenies of the reaction center proteins, chlorophyll synthesis enzymes, and the species tree of bacteria are best explained if both types of photochemical reaction centers evolved before the diversification of the known phyla of phototrophic bacteria. The primordial phototrophic ancestor must have had both Type I and Type II reaction centers.

  18. Unmetallated and metallated phthalocyanines bearing oxadiazole groups: Synthesis, photophysical and photochemical studies

    Energy Technology Data Exchange (ETDEWEB)

    Nas, Asiye [Department of Chemistry, Karadeniz Technical University, 61080 Trabzon (Turkey); Kantekin, Halit, E-mail: halit@ktu.edu.tr [Department of Chemistry, Karadeniz Technical University, 61080 Trabzon (Turkey); Durmuş, Mahmut [Gebze Institute of Technology, Department of Chemistry, PO Box 141, Gebze, 41400 Kocaeli (Turkey); Gümrükçüoğlu, Nurhan [Department of Chemistry, Karadeniz Technical University, 61080 Trabzon (Turkey)

    2014-10-15

    Unmetallated (4) and metallated (zinc(II), cobalt(II), lead(II)) phthalocyanines (5–7) carrying four 4-(4-(5-phenyl-1,3,4-oxadiazol-2-yl)phenoxy) groups on the peripheral positions were synthesized by cyclotetramerization of 4-(4-(5-phenyl-1,3,4-oxadiazol-2-yl)phenoxy)phthalonitrile (3) in the presence of corresponding metal salts (zinc(II) acetate, cobalt(II) chloride, lead(II) oxide) for metallated and without any metal for unmetallated phthalocyanines. The obtained organo-soluble phthalocyanines were characterized by infrared, electronic absorption, nuclear magnetic resonance and mass spectral techniques and elemental analysis as well. The photophysical and photochemical properties of newly synthesized tetra-substituted unmetallated (4), zinc(II) (5) and lead(II) (7) phthalocyanines were reported in N,N-dimetilformamid (DMF). The synthesized phthalocyanine compound 6 was not evaluated for photophysical and photochemical studies due to open shell and paramagnetic behavior of cobalt(II) metal ions in the phthalocyanine cavity. - Highlights: • Synthesis of unmetallated and metallated phthalocyanines. • Photophysical and photochemical properties of tetra-substituted phthalocyanines. • Characterization of organosoluble phthalocyanines by several spectral techniques.

  19. Anaerobiosis induced state transition: a non photochemical reduction of PQ pool mediated by NDH in Arabidopsis thaliana.

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    Sreedhar Nellaepalli

    Full Text Available BACKGROUND: Non photochemical reduction of PQ pool and mobilization of LHCII between PSII and PSI are found to be linked under abiotic stress conditions. The interaction of non photochemical reduction of PQ pool and state transitions associated physiological changes are critically important under anaerobic condition in higher plants. METHODOLOGY/FINDINGS: The present study focused on the effect of anaerobiosis on non-photochemical reduction of PQ pool which trigger state II transition in Arabidopsis thaliana. Upon exposure to dark-anaerobic condition the shape of the OJIP transient rise is completely altered where as in aerobic treated leaves the rise is unaltered. Rise in F(o and F(J was due to the loss of oxidized PQ pool as the PQ pool becomes more reduced. The increase in F(o' was due to the non photochemical reduction of PQ pool which activated STN7 kinase and induced LHCII phosphorylation under anaerobic condition. Further, it was observed that the phosphorylated LHCII is migrated and associated with PSI supercomplex increasing its absorption cross-section. Furthermore, evidences from crr2-2 (NDH mutant and pgr5 mutants (deficient in non NDH pathway of cyclic electron transport have indicated that NDH is responsible for non photochemical reduction of the PQ pool. We propose that dark anaerobic condition accelerates production of reducing equivalents (such as NADPH by various metabolic pathways which reduce PQ pool and is mediated by NDH leading to state II transition. CONCLUSIONS/SIGNIFICANCE: Anaerobic condition triggers non photochemical reduction of PQ pool mediated by NDH complex. The reduced PQ pool activates STN7 kinase leading to state II transition in A. thaliana.

  20. Metal hybrid nanoparticles for catalytic organic and photochemical transformations.

    Science.gov (United States)

    Song, Hyunjoon

    2015-03-17

    In order to understand heterogeneous catalytic reactions, model catalysts such as a single crystalline surface have been widely studied for many decades. However, catalytic systems that actually advance the reactions are three-dimensional and commonly have multiple components including active metal nanoparticles and metal oxide supports. On the other hand, as nanochemistry has rapidly been developed and been applied to various fields, many researchers have begun to discuss the impact of nanochemistry on heterogeneous catalysis. Metal hybrid nanoparticles bearing multiple components are structurally very close to the actual catalysts, and their uniform and controllable morphology is suitable for investigating the relationship between the structure and the catalytic properties in detail. In this Account, we introduce four typical structures of metal hybrid nanoparticles that can be used to conduct catalytic organic and photochemical reactions. Metal@silica (or metal oxide) yolk-shell nanoparticles, in which metal cores exist in internal voids surrounded by thin silica (or metal oxide) shells, exhibited extremely high thermal and chemical stability due to the geometrical protection of the silica layers against the metal cores. The morphology of the metal cores and the pore density of the hollow shells were precisely adjusted to optimize the reaction activity and diffusion rates of the reactants. Metal@metal oxide core-shell nanoparticles and inverted structures, where the cores supported the shells serving an active surface, exhibited high activity with no diffusion barriers for the reactants and products. These nanostructures were used as effective catalysts for various organic and gas-phase reactions, including hydrogen transfer, Suzuki coupling, and steam methane reforming. In contrast to the yolk- and core-shell structures, an asymmetric arrangement of distinct domains generated acentric dumbbells and tipped rods. A large domain of each component added multiple

  1. Density-functional study of plutonium monoxide monohydride

    Science.gov (United States)

    Qiu, Ruizhi; Lu, Haiyan; Ao, Bingyun; Tang, Tao; Chen, Piheng

    2017-03-01

    The structural, electronic, mechanical, optical, thermodynamic properties of plutonium monoxide monohydride (PuOH) are studied by density-functional calculations within the framework of LDA/GGA and LDA/GGA+U. From the total energy calculation, the lowest-energy crystal structure of PuOH is predicted to have space group F 4 bar 3 m (No. 216). Within the LDA+U framework, the calculated lattice parameter of F 4 bar 3 m -PuOH is in good agreement with the experimental value and the corresponding ground state is predicted to be an antiferromagnetic charge-transfer insulator. Furthermore, we investigate the bonding character of PuOH by analyzing the electron structure and find that there are a stronger Pu-O bond and a weaker Pu-H bond. The mechanical properties including the elastic constants, elastic moduli and Debye's temperature, and the optical properties including the reflectivity and absorption coefficient are also calculated. We then compute the phonon spectrum which verified the dynamical stability of F 4 bar 3 m -PuOH. Some thermodynamic quantities such as the specific heat are evaluated. Finally we calculate the formation energy of PuOH, and the reaction energies for the oxidation of PuOH and PuOH-coated Pu, which are in reasonable agreement with the experimental values.

  2. Regulation of ROS Production and Vascular Function by Carbon Monoxide

    Directory of Open Access Journals (Sweden)

    Yoon Kyung Choi

    2012-01-01

    Full Text Available Carbon monoxide (CO is a gaseous molecule produced from heme by heme oxygenase (HO. CO interacts with reduced iron of heme-containing proteins, leading to its involvement in various cellular events via its production of mitochondrial reactive oxygen species (ROS. CO-mediated ROS production initiates intracellular signal events, which regulate the expression of adaptive genes implicated in oxidative stress and functions as signaling molecule for promoting vascular functions, including angiogenesis and mitochondrial biogenesis. Therefore, CO generated either by exogenous delivery or by HO activity can be fundamentally involved in regulating mitochondria-mediated redox cascades for adaptive gene expression and improving blood circulation (i.e., O2 delivery via neovascularization, leading to the regulation of mitochondrial energy metabolism. This paper will highlight the biological effects of CO on ROS generation and cellular redox changes involved in mitochondrial metabolism and angiogenesis. Moreover, cellular mechanisms by which CO is exploited for disease prevention and therapeutic applications will also be discussed.

  3. Heme oxygenase-1 and carbon monoxide in pulmonary medicine.

    Science.gov (United States)

    Slebos, Dirk-Jan; Ryter, Stefan W; Choi, Augustine M K

    2003-01-01

    Heme oxygenase-1 (HO-1), an inducible stress protein, confers cytoprotection against oxidative stress in vitro and in vivo. In addition to its physiological role in heme degradation, HO-1 may influence a number of cellular processes, including growth, inflammation, and apoptosis. By virtue of anti-inflammatory effects, HO-1 limits tissue damage in response to proinflammatory stimuli and prevents allograft rejection after transplantation. The transcriptional upregulation of HO-1 responds to many agents, such as hypoxia, bacterial lipopolysaccharide, and reactive oxygen/nitrogen species. HO-1 and its constitutively expressed isozyme, heme oxygenase-2, catalyze the rate-limiting step in the conversion of heme to its metabolites, bilirubin IXalpha, ferrous iron, and carbon monoxide (CO). The mechanisms by which HO-1 provides protection most likely involve its enzymatic reaction products. Remarkably, administration of CO at low concentrations can substitute for HO-1 with respect to anti-inflammatory and anti-apoptotic effects, suggesting a role for CO as a key mediator of HO-1 function. Chronic, low-level, exogenous exposure to CO from cigarette smoking contributes to the importance of CO in pulmonary medicine. The implications of the HO-1/CO system in pulmonary diseases will be discussed in this review, with an emphasis on inflammatory states.

  4. Heme oxygenase-1 and carbon monoxide in pulmonary medicine

    Directory of Open Access Journals (Sweden)

    Choi Augustine MK

    2003-08-01

    Full Text Available Abstract Heme oxygenase-1 (HO-1, an inducible stress protein, confers cytoprotection against oxidative stress in vitro and in vivo. In addition to its physiological role in heme degradation, HO-1 may influence a number of cellular processes, including growth, inflammation, and apoptosis. By virtue of anti-inflammatory effects, HO-1 limits tissue damage in response to proinflammatory stimuli and prevents allograft rejection after transplantation. The transcriptional upregulation of HO-1 responds to many agents, such as hypoxia, bacterial lipopolysaccharide, and reactive oxygen/nitrogen species. HO-1 and its constitutively expressed isozyme, heme oxygenase-2, catalyze the rate-limiting step in the conversion of heme to its metabolites, bilirubin IXα, ferrous iron, and carbon monoxide (CO. The mechanisms by which HO-1 provides protection most likely involve its enzymatic reaction products. Remarkably, administration of CO at low concentrations can substitute for HO-1 with respect to anti-inflammatory and anti-apoptotic effects, suggesting a role for CO as a key mediator of HO-1 function. Chronic, low-level, exogenous exposure to CO from cigarette smoking contributes to the importance of CO in pulmonary medicine. The implications of the HO-1/CO system in pulmonary diseases will be discussed in this review, with an emphasis on inflammatory states.

  5. Heme oxygenase-1/carbon monoxide: from metabolism to molecular therapy.

    Science.gov (United States)

    Ryter, Stefan W; Choi, Augustine M K

    2009-09-01

    Heme oxygenase-1 (HO-1), a ubiquitous inducible stress-response protein, serves a major metabolic function in heme turnover. HO activity cleaves heme to form biliverdin-IXalpha, carbon monoxide (CO), and iron. Genetic experiments have revealed a central role for HO-1 in tissue homeostasis, protection against oxidative stress, and in the pathogenesis of disease. Four decades of research have witnessed not only progress in elucidating the molecular mechanisms underlying the regulation and function of this illustrious enzyme, but also have opened remarkable translational applications for HO-1 and its reaction products. CO, once regarded as a metabolic waste, can act as an endogenous mediator of cellular signaling and vascular function. Exogenous application of CO by inhalation or pharmacologic delivery can confer cytoprotection in preclinical models of lung/vascular injury and disease, based on anti-apoptotic, anti-inflammatory, and anti-proliferative properties. The bile pigments, biliverdin and bilirubin, end products of heme degradation, have also shown potential as therapeutics in vascular disease based on anti-inflammatory and anti-proliferative activities. Further translational and clinical trials research will unveil whether the HO-1 system or any of its reaction products can be successfully applied as molecular medicine in human disease.

  6. Reduction of carbon monoxide. Past research summary

    Energy Technology Data Exchange (ETDEWEB)

    Schrock, R.R.

    1981-10-01

    Research programs for the year on the preparation, characterization, and reactions of binuclear tantalum complexes are described. All evidence to date suggest the following of these dimeric molecules: (1) the dimer does not break into monomers under mild conditions; (2) intermolecular hydride exchange is not negligible, but it is slow; (3) intermolecular non-ionic halide exchange is fast; (4) the ends of the dimers can rotate partially with respect to one another. The binuclear tantalum hydride complexes were found to react with carbon monoxide to give a molecule which is the only example of reduction of CO by a transition metal hydride to give a complex containing a CHO ligand. Isonitrides also reacted in a similar manner with dimeric tantalum hydride. (ATT)

  7. Regulation of multiple carbon monoxide consumption pathways in anaerobic bacteria

    Directory of Open Access Journals (Sweden)

    Stephen M Techtmann

    2011-07-01

    Full Text Available Carbon monoxide (CO, well known as a toxic gas, is increasingly recognized as a key metabolite and signaling molecule. Microbial utilization of CO is quite common, evidenced by the rapid escalation in description of new species of CO-utilizing bacteria and archaea. Carbon monoxide dehydrogenase (CODH, the protein complex that enables anaerobic CO utilization has been well-characterized from an increasing number of microorganisms, however the regulation of multiple CO-related gene clusters in single isolates remains unexplored. Many species are extroraordinarily resistant to high CO concentrations, thiriving under pure CO at more than one atmosphere. We hypothesized that, in strains that can grow exclusively on CO, both carbon acquisition via the CODH/Acetyl CoA synthase complex and energy conservation via a CODH-linked hydrogenase must be differentially regulated in response to the availability of CO. The CO-sensing transcriptional activator, CooA is present in most CO-oxidizing bacteria. Here we present a genomic and phylogenetic survey of CODH operons and cooA genes found in CooA-containing bacteria. Two distinct groups of CooA homologs were found: One clade (CooA-1 is found in the majority of CooA containing bacteria, whereas the other clade (CooA-2 is found only in genomes that encode multiple CODH clusters, suggesting that the CooA-2 might be important for cross-regulation of competing CODH operons. Recombinant CooA-1 and CooA-2 regulators from the prototypical CO-utilizing bacterium Carboxydothermus hydrogenoformans were purified, and promoter binding analyses revealed that CooA-1 specifically regulates the hydrogenase-linked CODH, whereas CooA-2 is able to regulate both the hydrogenase-linked CODH and the CODH/ACS operons. These studies point to the ability of dual CooA homologs to partition CO into divergent CO-utilizing pathways resulting in efficient consumption of a single limiting growth substrate available across a wide range of

  8. Experimental Study of Nonequilibrium Electrodeposition of Nanostructures on Copper and Nickel for Photochemical Fuel Cell Application

    Directory of Open Access Journals (Sweden)

    Rajesh K. Shanmugam

    2011-01-01

    Full Text Available To increase the performance of photochemical fuel cells, nonequilibrium electrodeposition has been performed on Cu and Ni to make photosensitive anodes. Processing parameters including electrolyte concentration, and electrode potential were studied using cyclic voltammetry. Scanning electron microscopy (SEM and X-ray Spectroscopy (EDS were performed to understand the formation of the nanostructures during the nonequilibrium deposition of copper fractals. An increase in the deposition rate was observed with the increase in electrolyte concentration (from 0.05 M to 1.0 M. Similar trend was found when the cathode potential was decreased from −0.5 V to −4.5 V. The effect of substrate material was also examined. Porous fractal structures on copper were achieved, while the deposited material showed high density of surface cracks on nickel. The fractal structures deposited on copper electrode with the increased surface area were converted into copper oxide by oxidation in air. Such oxide samples were made into anodes for photochemical fuel cell application. We demonstrated that an increase in the magnitude of open circuit output voltage is associated with the increase in the fractal surface area under the ultraviolet irradiation test conditions. However, the electrodeposited fractals on nickel showed very limited increase in the magnitude of open circuit voltage.

  9. Syncope Associated with Carbon Monoxide Poisoning due to Narghile Smoking

    Directory of Open Access Journals (Sweden)

    Seda Ozkan

    2013-01-01

    Full Text Available Narghile smoking is a traditional method of tobacco use, and it has been practiced extensively for 400 years. Traditionally, narghile smoking is a matter of culture mainly in Middle East, Asia, and Africa. In recent years, its use as a social activity has increased worldwide, especially among young people. Narghile smoking is an unusual cause of carbon monoxide poisoning. Narghile smoking, compared to cigarette smoking, can result in more smoke exposure and greater levels of carbon monoxide. We present an acute syncope case of a 19-year-old male patient who had carbon monoxide poisoning after narghile smoking.

  10. Exhaled carbon monoxide in asthmatics: a meta-analysis

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    Huang Mao

    2010-04-01

    Full Text Available Abstract Background The non-invasive assessment of airway inflammation is potentially advantageous in asthma management. Exhaled carbon monoxide (eCO measurement is cheap and has been proposed to reflect airway inflammation and oxidative stress but current data are conflicting. The purpose of this meta-analysis is to determine whether eCO is elevated in asthmatics, is regulated by steroid treatment and reflects disease severity and control. Methods A systematic search for English language articles published between 1997 and 2009 was performed using Medline, Embase and Cochrane databases. Observational studies comparing eCO in non-smoking asthmatics and healthy subjects or asthmatics before and after steroid treatment were included. Data were independently extracted by two investigators and analyzed to generate weighted mean differences using either a fixed or random effects meta-analysis depending upon the degree of heterogeneity. Results 18 studies were included in the meta-analysis. The eCO level was significantly higher in asthmatics as compared to healthy subjects and in intermittent asthma as compared to persistent asthma. However, eCO could not distinguish between steroid-treated asthmatics and steroid-free patients nor separate controlled and partly-controlled asthma from uncontrolled asthma in cross-sectional studies. In contrast, eCO was significantly reduced following a course of corticosteroid treatment. Conclusions eCO is elevated in asthmatics but levels only partially reflect disease severity and control. eCO might be a potentially useful non-invasive biomarker of airway inflammation and oxidative stress in nonsmoking asthmatics.

  11. Photochemical treatment as an alternative to improve the quality of wastewater after advanced primary treatment.

    Directory of Open Access Journals (Sweden)

    Hernández Fernando

    2014-12-01

    Full Text Available The present research contains the photochemical treatment (PCT of residual wastewater effluent derived from an advanced primary treatment process (APT. The application employed an ultraviolet light system, hydrogen peroxide and ozone as a free hydroxyl’s radicals generator; strong oxidants for the organic contaminants mineralization which affects the water quality. The aliquots of the APT and PCT were analyzed by determination of the parameters as the color, turbidity, electric conductivity, COD, UV-Vis spectrometry, anion and cation techniques, enabling the determination of the photo-oxidative wastewater treatment efficiency. The microbiological assays denote the one hundred percent photo-oxidative effectiveness for the removal of undesirable microorganisms. After the treatment, the water is suitable for its reuse, commercialization or spill into a body receptor without any risk for the environment or the health.

  12. A green chemistry of graphene: photochemical reduction towards monolayer graphene sheets and the role of water adlayers.

    Science.gov (United States)

    Li, Xin-Hao; Chen, Jie-Sheng; Wang, Xinchen; Schuster, Manfred E; Schlögl, Robert; Antonietti, Markus

    2012-04-01

    Clean sheets: Stable aqueous dispersions of graphene sheets (GSs) are obtained by exposing graphene oxide to irradiation with light at room temperature, without using any chemical additives. The photochemical reduction method is sustainable and scalable, repairs a majority of defects in the graphene layers, and can be used to fine-tune surface functional groups. Interestingly, the aqueous GS dispersions are stable without any added surfactant. The existence of a water layer that is strongly bound to GS is evidenced.

  13. Identification of the Active Species in Photochemical Hole Scavenging Reactions of Methanol on TiO2

    Energy Technology Data Exchange (ETDEWEB)

    Shen, Mingmin; Henderson, Michael A.

    2011-11-03

    Molecular and dissociative methanol adsorption species were prepared on rutile TiO2(110) surfaces to study photocatalytic oxidation of methanol in ultrahigh vacuum (UHV) using temperature-programmed desorption (TPD). Adsorbed methoxy groups (CH3O-) were found to be the photoactive form of adsorbed methanol converted to adsorbed formaldehyde and a surface OH group by hole-mediated C-H bond cleavage. These results suggest that adsorbed methoxy is the effective hole scavenger in photochemical reactions involving methanol.

  14. Laser-Time Interaction XII: Photochemical, Photothermal, and Photomechanical

    Science.gov (United States)

    Duncan, Donald D.; Jacques, Steven L.; Johnson, Peter C.

    2001-01-01

    This proceedings contains papers on the following topics: photodynamic therapy, immunotherapy, pulsed laser effects, polarized light interactions, photochemical interactions, occular laser effects,thermal interactions, laser shaping of cartilage.

  15. The chemistry and transport of methane and carbon monoxide in the troposphere

    Science.gov (United States)

    Peters, L. K.; Chameides, W. L.

    1980-01-01

    The present understanding of the physical and chemical behavior of methane, carbon monoxide and the chemical species involved in the conversion of CH4 to CO in the troposphere is reviewed. Following a brief summary of CO and CH4 emission and reactions in urban areas, attention is given to measurements of the spatial and temporal distributions of CO and CH4 in the rural atmosphere, the contribution of the oceans to atmospheric CO and CH4 concentrations, and interactions of CH4 and CO with soils and vegetation. Estimates of the transport of CH4 and CO from the troposphere to the stratosphere are discussed, and photochemical reactions of the constituents are examined. Two- and three-dimensional models for CH4 and CO transport are presented, and possible future variations in atmospheric abundances of the molecules are considered. Finally, present estimates of the global methane and carbon dioxide budgets are summarized, and it is pointed out that, despite the large contribution of anthropogenic sources, the budgets appear to be in balance.

  16. Remotely Sensing the Photochemical Reflectance Index (PRI)

    Science.gov (United States)

    Vanderbilt, Vern

    2015-01-01

    In remote sensing, the Photochemical Reflectance Index (PRI) provides insight into physiological processes occurring inside the leaves in a stand of plants. Developed by Gamon et al., (1990 and 1992), PRI evolved from laboratory measurements of the reflectance of individual leaves (Bilger et al.,1989). Yet in a remotely sensed image, a pixel measurement may include light from both reflecting and transmitting leaves. We conducted laboratory experiments comparing values of PRI based upon polarized reflectance and transmittance measurements of water and nutrient stressed leaves. We illuminated single detached leaves using a current controlled light source (Oriel model 66881) and measured the leaf weight using an analytical balance (Mettler model AE 260) and the light reflected and transmitted by the leaf during dry down using two Analytical Spectral Devices spectroradiometers. Polarizers on the incident and reflected light beams allowed us to divide the leaf reflectance into two parts: a polarized surface reflectance and a non-polarized 'leaf interior' reflectance. Our results underscore the importance when calculating PRI of removing the leaf surface reflection, which contains no information about physiological processes ongoing in the leaf interior. The results show that the leaf physiology information is in the leaf interior reflectance, not the leaf transmittance. Applied to a plant stand, these results suggest use of polarization measurements in sun-view directions that minimize the number of sunlit transmitting leaves in the sensor field of view.

  17. Laser photochemical reaction dynamics in formaldehyde

    Energy Technology Data Exchange (ETDEWEB)

    Zughul, M.B.A.

    1978-08-01

    Appearance rate constants of molecular photochemical products were measured following laser photolysis of formaldehyde in the near ultraviolet. The pressure dependence of appearance rates was studied for three formaldehyde isotopic species: H/sub 2/CO, HDCO, and D/sub 2/CO. The effect of added foreign gases on those rates in H/sub 2/CO has been determined for He, Ar, Xe, and NO. The energy dependence of photodissociation rates has been examined following laser photolysis at 354.7 and 299.1 nm and the results compared with earlier data obtained at 337.1 nm. The corresponding appearance rates measured for other carbonyls such as acrolein, propynal, ketene, and cyclobutanone were found to be much faster and greater than gas kinetic, indicating a photodissociation mechanism which is different from that of formaldehyde. The decay rates of CO(v = 1) have been measured for several collision partners including H/sub 2/CO, HDCO, acrolein, ketene, cis-2-butene, and cyclobutanone. Appearance rates for the radical dissociation channel in formaldehyde by monitoring H-atom production were measured using three different techniques: resonance fluorescence, resonance absorption, and two-photon excited fluorescence of Hydrogen Lyman-..cap alpha.. photons. 152 references, 45 figures, 16 tables.

  18. Photochemical Phenomenology Model for the New Millenium

    Science.gov (United States)

    Bishop, James; Evans, J. Scott

    2000-01-01

    This project tackles the problem of conversion of validated a priori physics-based modeling capabilities, specifically those relevant to the analysis and interpretation of planetary atmosphere observations, to application-oriented software for use in science and science-support activities. The software package under development, named the Photochemical Phenomenology Modeling Tool (PPMT), has particular focus on the atmospheric remote sensing data to be acquired by the CIRS instrument during the CASSINI Jupiter flyby and orbital tour of the Saturnian system. Overall, the project has followed the development outline given in the original proposal, and the Year 1 design and architecture goals have been met. Specific accomplishments and the difficulties encountered are summarized in this report. Most of the effort has gone into complete definition of the PPMT interfaces within the context of today's IT arena: adoption and adherence to the CORBA Component Model (CCM) has yielded a solid architecture basis, and CORBA-related issues (services, specification options, development plans, etc.) have been largely resolved. Implementation goals have been redirected somewhat so as to be more relevant to the upcoming CASSINI flyby of Jupiter, with focus now being more on data analysis and remote sensing retrieval applications.

  19. Locating conical intersections relevant to photochemical reactions

    Energy Technology Data Exchange (ETDEWEB)

    Dick, Bernhard [Institut fuer Physikalische und Theoretische Chemie, Universitaet Regensburg, D 93040 Regensburg (Germany)], E-mail: Bernhard.Dick@chemie.uni-regensburg.de; Haas, Yehuda; Zilberg, Shmuel [Department of Physical Chemistry and the Farkas Center for Light-induced Processes, The Hebrew University of Jerusalem, Jerusalem 91904 (Israel)

    2008-05-23

    A new computerized method for locating conical intersections of interest in photochemistry is presented. The search is based on the Longuet-Higgins phase change theorem (Berry phase) which provides the subspace required for the initial search. The subspace is approximated as a plane containing three stable structures lying on a Longuet-Higgins loop. The search is conducted for a minimum of {delta}E, the energy difference between two electronic states. It is started using up to three points within the circle defined by the three structures; symmetry, if relevant, is helpful but not essential. Since a two-dimensional subspace of the large 3N - 6 space is used, the search that uses either Cartesian or internal coordinates is efficient and yields a degeneracy after a few iterations. Given that not all degrees of freedom are included in the search, usually a high lying part of the conical intersection is initially located. The system is subsequently optimized along all coordinates keeping {delta}E as close to zero as desired. The method is demonstrated for the symmetric H{sub 3} system and also for the butadiene-cyclobutene-bicyclobutane system in which the three stable structures are not equivalent. The method is general and can be extended to any photochemical system.

  20. Improving a Mars photochemical model with thermodynamics

    Science.gov (United States)

    Delgado-Bonal, A.; Martin-Torres, F. J.; Simoncini, E.

    2012-12-01

    Different conditions of temperature and pressure drive the chemistry of a planetary atmosphere to different steady states. However, the different thermodynamic conditions are not considered in many studies about the abundance of liquid water, methane or other important compounds called sometimes biomarkers, leading to wrong calculations. We have adapted a photochemical model for Mars atmosphere [1] to the proper thermodynamical conditions and coupled it with realistic profiles of Temperature and Pressure previously calculated with PRAMS GCM. As we have shown previously [2], the influence of T,P and molar fraction in the Gibbs Free Energy calculations and therefore in the kinetics of the gases in a planetary atmosphere has a huge influence in the final steady state and concentrations. The study is applied to different compounds and determine their abundance with real Mars conditions. The existence and reactivity of liquid water on Mars is highly linked with the presence of other compounds in the atmosphere such as Ozone, OH or CH4, and the determination of those also require the thermodynamical studies. [1 ] Franck Lefèvre and François Forget. Observed variations of methane on Mars unexplained by known atmospheric chemistry and physics. Nature 460, 720-723 (6 August 2009) [2] Simoncini E., Delgado-Bonal A., Martin-Torres F.J., Accounting thermodynamic conditions in chemical models of planetary atmospheres. Submitted to Astrophysical Journal.

  1. Photochemical Patterning of Ionically Cross-Linked Hydrogels

    Directory of Open Access Journals (Sweden)

    Marion Bruchet

    2013-08-01

    Full Text Available Iron(III cross-linked alginate hydrogel incorporating sodium lactate undergoes photoinduced degradation, thus serving as a biocompatible positive photoresist suitable for photochemical patterning. Alternatively, surface etching of iron(III cross-linked hydrogel contacting lactic acid solution can be used for controlling the thickness of the photochemical pattering. Due to biocompatibility, both of these approaches appear potentially useful for advanced manipulation with cell cultures including growing cells on the surface or entrapping them within the hydrogel.

  2. Investigation of the Photochemical Method for Uranium Isotope Separation

    Science.gov (United States)

    Urey, H. C.

    1943-07-10

    To find a process for successful photochemical separation of isotopes several conditions have to be fulfilled. First, the different isotopes have to show some differences in the spectrum. Secondly, and equally important, this difference must be capable of being exploited in a photochemical process. Parts A and B outline the physical and chemical conditions, and the extent to which one might expect to find them fulfilled. Part C deals with the applicability of the process.

  3. Degradation of artificial sweeteners via direct and indirect photochemical reactions.

    Science.gov (United States)

    Perkola, Noora; Vaalgamaa, Sanna; Jernberg, Joonas; Vähätalo, Anssi V

    2016-07-01

    We studied the direct and indirect photochemical reactivity of artificial sweeteners acesulfame, saccharin, cyclamic acid and sucralose in environm entally relevant dilute aqueous solutions. Aqueous solutions of sweeteners were irradiated with simulated solar radiation (>290 nm; 96 and 168 h) or ultraviolet radiation (UVR; up to 24 h) for assessing photochemical reactions in surface waters or in water treatment, respectively. The sweeteners were dissolved in deionised water for examination of direct photochemical reactions. Direct photochemical reactions degraded all sweeteners under UVR but only acesulfame under simulated solar radiation. Acesulfame was degraded over three orders of magnitude faster than the other sweeteners. For examining indirect photochemical reactions, the sweeteners were dissolved in surface waters with indigenous dissolved organic matter or irradiated with aqueous solutions of nitrate (1 mg N/L) and ferric iron (2.8 mg Fe/L) introduced as sensitizers. Iron enhanced the photodegradation rates but nitrate and dissolved organic matter did not. UVR transformed acesulfame into at least three products: iso-acesulfame, hydroxylated acesulfame and hydroxypropanyl sulfate. Photolytic half-life was one year for acesulfame and more than several years for the other sweeteners in surface waters under solar radiation. Our study shows that the photochemical reactivity of commonly used artificial sweeteners is variable: acesulfame may be sensitive to photodegradation in surface waters, while saccharin, cyclamic acid and sucralose degrade very slowly even under the energetic UVR commonly used in water treatment.

  4. An interesting cause of pulmonary emboli: Acute carbon monoxide poisoning

    Energy Technology Data Exchange (ETDEWEB)

    Sevinc, A.; Savli, H.; Atmaca, H. [Gaziantep University, Gaziantep (Turkey). School of Medicine

    2005-07-01

    Carbon monoxide poisoning, a public health problem of considerable significance, is a relatively frequent event today, resulting in thousands of hospitalizations annually. A 70-year-old lady was seen in the emergency department with a provisional diagnosis of carbon monoxide poisoning. The previous night, she slept in a tightly closed room heated with coal ember. She was found unconscious in the morning with poor ventilation. She had a rare presentation of popliteal vein thrombosis, pulmonary emboli, and possible tissue necrosis with carbon monoxide poisoning. Oxygen treatment with low-molecular-weight heparin (nadroparine) and warfarin therapy resulted in an improvement in both popliteal and pulmonary circulations. In conclusion, the presence of pulmonary emboli should be sought in patients with carbon monoxide poisoning.

  5. US EPA Region 9 carbon monoxide designated areas

    Data.gov (United States)

    U.S. Environmental Protection Agency — Polygon Feature class of Nonattainment Areas for Carbon Monoxide. Nonattainment areas are geographic areas which have not met National Ambient Air Quality Standards...

  6. Carbon monoxide poisoning in the United Arab Emirates.

    Science.gov (United States)

    Al Kaabi, Juma M; Wheatley, Andrew D; Barss, Peter; Al Shamsi, Mariam; Lababidi, Anis; Mushtaq, Ahmed

    2011-01-01

    Carbon monoxide (CO) poisoning is rare in the Arabian Peninsula and occurs almost exclusively during the winter months. Knowledge and perception of the hazards of carbon monoxide is limited. Migrant workers from warm climates appear particularly at risk. We investigated 46 cases of carbon monoxide poisoning presenting at emergency departments from 2007-2009 of the two main hospitals in Al Ain city, United Arab Emirates. Interviews, hospital records, and administered questionnaires were used to collect the data. Among the 46 cases investigated, 24 (52%) were males. Foreign nationals compromised 80% of the cases and the incidence was 3.1 cases per 100,000 residents per year. Burning charcoal in poorly ventilated residences was the predominant source of the carbon monoxide poisoning. Almost all cases (98%) were admitted during the winter months, most in the early morning hours. Carboxyhaemoglobin (COHb) was significantly increased in cases with loss of consciousness and depressed consciousness. There were no reported fatalities.

  7. Same Exposure, Various Clinical Pictures: The Carbon Monoxide Enigma

    Directory of Open Access Journals (Sweden)

    Musa Salmanoglu

    2013-02-01

    Full Text Available -Children and adolescents exposed to the same source of carbon monoxide have been shown to demonstrate different clinical pictures (1,2. The same condition probably may be extrapolated between children with varying ages and hence lung surface areas. Smaller children will receive larger doses of carbon monoxide, because they have greater lung surface area/body weight ratios and increased minute volumes/weight ratios. As carbon monoxide accumulation is expected to be more significant nearer to the ground, another explanation for varying clinical pictures in poisoning events may be the different level of sleeping positions of the casualties. Herein, we report a cluster poisoning of carbon monoxide affecting 5 children from the same family at the same time but in different clinical pictures. [TAF Prev Med Bull 2013; 12(1.000: 118-118

  8. Carbon monoxide exposure in blast furnace workers.

    Science.gov (United States)

    Lewis, S; Mason, C; Srna, J

    1992-09-01

    This study investigated the occupational exposure to carbon monoxide (CO) of a group of blast furnace workers from an integrated steelworks, compared to a control group having no significant occupational CO exposure from other areas in the same works. The study was undertaken in 1984 at Port Kembla, New South Wales. Carboxyhaemoglobin (COHb) levels before and after an eight-hour work shift were measured in 98 male steelworkers: 52 from two CO-exposed iron blast furnaces and 46 controls from production areas in the same steelworks. The sample was stratified by smoking habits. Environmental air CO levels had been found to be consistently higher on one furnace than on the other. Absorption of CO from the working environment occurred in workers on the blast furnace with higher CO levels, regardless of smoking habits. On this blast furnace, some readings of COHb levels after a workshift in nonsmokers approached the proposed Australian occupational limit of 5 per cent COHb saturation. Overall, workers with the highest occupational exposure who smoked most heavily had the highest absorption of CO over a work shift. Biological monitoring gives an accurate measure of individual worker 'dose' of CO from all sources. Both environmental monitoring and biological monitoring need to be included as part of a program for controlling occupational CO exposure.

  9. First-Principles Investigations on Europium Monoxide

    KAUST Repository

    Wang, Hao

    2011-05-01

    Europium monoxide is both an insulator and a Heisenberg ferromagnet (Tc=69 K). In the present thesis, the author has investigated the electronic structure of different types of EuO by density functional theory. The on-site Coulomb interaction of the localized Eu 4f and 5d electrons, which is wrongly treated in the standard generalized gradient approximation method, is found to be crucial to obtain the correct insulating ground state as observed in experiments. Our results show that the ferromagnetism is stable under pressure, both hydrostatic and uniaxial. For both types of pressure an insulator-metal transition is demonstrated. Moreover, the experimentally observed insulator-metal transition in oxygen deficient and gadolinium-doped EuO is reproduced in our calculations for impurity concentrations of 6.25% and 25%. Furthermore, a 10- layer EuO thin film is theoretically predicted to be an insulator with a narrow band gap of around 0.08 eV, while the Si/EuO interface shows metallic properties with the Si and O 2p as well as Eu 5d bands crossing the Fermi level.

  10. Chlorine Monoxide in the Antarctic Spring Stratosphere.

    Science.gov (United States)

    Jaramillo-Ayerbe, Mauricio

    1988-06-01

    A series of observations of stratospheric chlorine monoxide (ClO) were carried out during the austral springs of 1986 and 1987 in McMurdo Station, Antarctica, as part of two experimental campaigns sent to investigate the seasonal decrease in ozone over the antarctic continent (the ozone "hole"). Measurements of the vertical distribution of ClO were obtained by high resolution ground-based emission spectroscopy at 278 GHz, using the Stony Brook mm-wave receiver. They show the presence of an anomalous layer of lower stratospheric ClO which is not observed at other latitudes. This anomalous layer is centered at ~20 km altitude and exhibits a pronounced diurnal variation, reaching a maximum at midday and disappearing at night. During the period of Sep. 20-24, 1987, the lower-stratospheric ClO had a maximum volume mixing ratio of 1.8_sp{+0cdot5}{ -0cdot9} ppbv. A normal ClO layer centered at ~36 km was also observed, with concentrations and diurnal behavior similar to those seen in tropical latitudes. These findings are evidence of anomalous chlorine chemistry taking place in the lower stratosphere during the antarctic spring, and indicate that increasing anthropogenic chlorine is a prime causative agent in the formation of the ozone hole.

  11. Sunlight technologies for photochemical deactivation of organic pollutants in water

    Energy Technology Data Exchange (ETDEWEB)

    Acher, A.; Fischer, E.; Tornheim, R. [The Volcani Center, Inst. of Soils and Water, Bet Dagan (Israel); Manor, Y. [Sheba Medical Center, Central Virology Lab., Ramat Gan (Israel)

    1997-12-31

    Sensitized-photochemical oxidation methods aimed at use in water treatment technologies for deactivation of biotic (microorganisms) and/or of xenobiotic (pesticides) pollutants in water were developed using global solar radiation or concentrated sunlight (up to 250 suns). The solar global radiation was used either for detoxification of industrial waste water from a pesticide factory to allow their discharge into the urban sewer, or for disinfection of domestric effluents to be used in crop irrigation. The disinfection process was eventually carried out in an experimental pilot-scale plant, capable of disinfection up to 50 m{sup 3}/h of effluent supplied by an activated sludge sewage treatment plant located in Tel-Aviv area. The treated effluents did not show any regrowth of the microorganisms during 7 days. The solar concentrated radiation experiments performed using facilities of the Sun Tower of The Weizman Institute of Science, Rehovot. The concentrated sunlight was provided by different combination of several computer controlled heliostates, up to 8, that track the sun and focus the received sunlight onto the target situated on the roof of the sun-tower. The sunlight intensities measured on the target reached up to 200 kW/m{sup 2}. The experiments were performed either batch- or continuous-wise. The water-samples exposed to disinfection were the above effluent, filtered and supplemented with vaccine strain poliovirus or with different concentrations of an industrial potential pollutant (bromacil), MB 2 mg/L and two concentrations of dissolved oxygen (8.0 or 40.0 mg O{sub 2}/L). An exposure time of 2-3 seconds at 150 kW/m{sup 2} was decreased the microorganisms alive (counts) by five orders of magnitude. A comparison between the two above water treatment technologies is presented. (orig./SR)

  12. A photochemically driven molecular-level abacus

    Science.gov (United States)

    Ashton; Ballardini; Balzani; Credi; Dress; Ishow; Kleverlaan; Kocian; Preece; Spencer; Stoddart; Venturi; Wenger

    2000-10-01

    sequence of photoinduced electron transfer processes? In order to find an answer to this question, the electrochemical, photophysical, and photochemical (under continuous and pulsed excitation) properties of the [2]rotaxane, its dumbbell-shaped component, and some model compounds containing electro- and photoactive units have been investigated. In an attempt to obtain the photoinduced abacus-like movement of the BPP34C10 macrocycle between the two stations, two strategies have been employed-one was based fully on processes that involved only the rotaxane components (intramolecular mechanism), while the other one required the help of external reactants (sacrificial mechanism). Both mechanisms imply a sequence of four steps (destabilization of the stable translational isomer, macrocyclic ring displacement, electronic reset, and nuclear reset) that have to compete with energy-wasteful steps. The results have demonstrated that photochemically driven switching can be performed successfully by the sacrificial mechanism, whereas, in the case of the intramolecular mechanism, it would appear that the electronic reset of the system is faster than the ring displacement.

  13. Topography of Photochemical Initiation in Molecular Materials

    Directory of Open Access Journals (Sweden)

    Edward D. Aluker

    2013-11-01

    Full Text Available We propose a fluctuation model of the photochemical initiation of an explosive chain reaction in energetic materials. In accordance with the developed model, density fluctuations of photo-excited molecules serve as reaction nucleation sites due to the stochastic character of interactions between photons and energetic molecules. A further development of the reaction is determined by a competition of two processes. The first process is growth in size of the isolated reaction cell, leading to a micro-explosion and release of the material from the cell towards the sample surface. The second process is the overlap of reaction cells due to an increase in their size, leading to the formation of a continuous reaction zone and culminating in a macro-explosion, i.e., explosion of the entire area, covering a large part of the volume of the sample. Within the proposed analytical model, we derived expressions of the explosion probability and the duration of the induction period as a function of the initiation energy (exposure. An experimental verification of the model was performed by exploring the initiation of pentaerythritol tetranitrate (PETN with the first harmonic of YAG: Nd laser excitation (1,064 nm, 10 ns, which has confirmed the adequacy of the model. This validation allowed us to make a few quantitative assessments and predictions. For example, there must be a few dozen optically excited molecules produced by the initial fluctuations for the explosive decomposition reaction to occur and the life-time of an isolated cell before the micro-explosion must be of the order of microseconds.

  14. Photochemical Formation of Sulfur-Containing Aerosols

    Science.gov (United States)

    Kroll, Jay A.; Vaida, Veronica

    2017-06-01

    In order to understand planetary climate systems, modeling the properties of atmospheric aerosols is vital. Aerosol formation plays an important role in planetary climates and is tied to feedback loops that can either warm or cool a planet. Sulfur compounds are known to play an important role in new particle aerosol formation and have been observed in a number of planetary atmospheres throughout our solar system. Our current understanding of sulfur chemistry explains much of what we observe in Earth's atmosphere; however, several discrepancies arise when comparing observations of the Venusian atmosphere with model predictions. This suggests that there are still problems in our fundamental understanding of sulfur chemistry. This is concerning given recent renewed interest in sulfate injections in the stratosphere for solar radiation management geo-engineering schemes. We investigate the role of sunlight as a potential driver of the formation of sulfur-containing aerosols. I will present recent work investigating the generation of large quantities of aerosol from the irradiation of mixtures of SO_2 with water and organic species, using a solar simulator that mimics the light that is available in the Earth's troposphere and the Venusian middle atmosphere. I will present on recent work done in our lab suggesting the formation of sulfurous acid, H_2SO_3, and describe experimental work that supports this proposed mechanism. Additionally I will present on new work showing the highly reactive nature of electronically excited SO_2 with saturated alkane species. The implications of this photochemically induced sulfur aerosol formation in the atmosphere of Earth and other planetary atmospheres will be discussed.

  15. Assessment of carbon monoxide values in smokers: a comparison of carbon monoxide in expired air and carboxyhaemoglobin in arterial blood

    DEFF Research Database (Denmark)

    Andersson, Mette F; Møller, Ann M

    2010-01-01

    Smoking increases perioperative complications. Carbon monoxide concentrations can estimate patients' smoking status and might be relevant in preoperative risk assessment. In smokers, we compared measurements of carbon monoxide in expired air (COexp) with measurements of carboxyhaemoglobin (COHb) ......) in arterial blood. The objectives were to determine the level of correlation and to determine whether the methods showed agreement and evaluate them as diagnostic tests in discriminating between heavy and light smokers....

  16. One-step surface selective modification of UV-curable hard coatings with photochemical metal organics

    Science.gov (United States)

    Lee, Yoon Kwang; Park, Chang-Sun; Park, Hyung-Ho

    2016-12-01

    An organic-inorganic hybrid bi-layer film with a selective distribution of inorganic components was synthesized from a one-pot process of UV irradiation. A photochemical metal oxide precursor (Sr 2-ethylhexanoate) varying from 0 to 4 wt% was dispersed in UV-curable coating materials. Under UV exposure, the bi-layer started reacting simultaneously but at different rates due to differences in the two UV-condensable components' reactivity. The effects of the dispersed inorganic component on the surface morphology and mechanical properties were investigated by atomic force microscopy and nanoindentation, respectively. The reaction process and rates were studied from linkage change using Fourier transform infrared spectroscopy at various UV exposure times (0-30 min). The elemental distribution and the interface on the coating layer were characterized by X-ray photoelectron spectroscopy from Ar etching, revealing continuous and gradual composition changes in depth. The results showed that a flattened and surface-selectively hardened SrO containing the coating film could be obtained by this simple process. Consequently, a small ratio of photochemical metal oxide reinforced the organic hard coating film's mechanical properties through the formation of an effective SrO top layer.

  17. Photochemical Hydrogen Abstraction and Electron Transfer Reactions of Tetrachlorobenzoquinone with Pyrimidine Nucleobases

    Institute of Scientific and Technical Information of China (English)

    Kun-hui Liu; Li-dan Wu; Xiao-ran Zou; Wen Yang; Qian Du; Hong-mei Su

    2011-01-01

    Pentachlorophenol,a widespread environmental pollutant that is possibly carcinogenic to humans,is metabolically oxidized to tetrachloroquinone (TCBQ) which can result in DNA damage.We have investigated the photochemical reaction dynamics of TCBQ with two pyrimidine type nucleobases (thymine and uracil) upon UVA (355 nm) excitation using the technique of nanosecond time-resolved laser flash photolysis.It has been found that 355 nm excitation populates TCBQ molecules to their triplet state 3TCBQ*,which are highly reactive towards thymine or uracil and undergo two parallel reactions,the hydrogen abstraction and electron transfer,leading to the observed photoproducts of TCBQH.and TCBQ.- in transient absorption spectra.The concomitantly produced nucleobase radicals and radical cations are expected to induce a series of oxidative or strand cleavage damage to DNA afterwards.By characterizing the photochemical hydrogen abstraction and electron transfer reactions,our results provide potentially important molecular reaction mechanisms for understanding the carcinogenic effects of pentachlorophenol and its metabolites TCBQ.

  18. Heterologous Production of an Energy-Conserving Carbon Monoxide Dehydrogenase Complex in the Hyperthermophile Pyrococcus furiosus

    Directory of Open Access Journals (Sweden)

    Gerrit Jan Schut

    2016-01-01

    Full Text Available Carbon monoxide (CO is an important intermediate in anaerobic carbon fixation pathways in acetogenesis and methanogenesis. In addition, some anaerobes can utilize CO as an energy source. In the hyperthermophilic archaeon Thermococcus onnurineus, which grows optimally at 80°C, CO oxidation and energy conservation is accomplished by a respiratory complex encoded by a 16-gene cluster containing a carbon monoxide dehydrogenase, a membrane-bound [NiFe]-hydrogenase and a Na+/H+ antiporter module. This complex oxidizes CO, evolves CO2 and H2, and generates a Na+ motive force that is used to conserve energy by a Na+-dependent ATP synthase. Herein we used a bacterial artificial chromosome to insert the 13.2 kb gene cluster encoding the CO-oxidizing respiratory complex of T. onnurineus into the genome of the heterotrophic archaeon, Pyrococcus furiosus, which grows optimally at 100°C. P. furiosus is normally unable to utilize CO, however, the recombinant strain readily oxidized CO and generated H2 at 80°C. Moreover, CO also served as an energy source and allowed the P. furiosus strain to grow with a limiting concentration of sugar or with peptides as the carbon source. Moreover, CO oxidation by P. furiosus was also coupled to the re-utilization, presumably for biosynthesis, of acetate generated by fermentation. The functional transfer of CO utilization between Thermococcus and Pyrococcus species demonstrated herein is representative of the horizontal gene transfer of an environmentally-relevant metabolic capability. The transfer of CO utilizing, hydrogen-producing genetic modules also has applications for biohydrogen production and a CO-based industrial platform for various thermophilic organisms.

  19. Carbon Monoxide Promotes Lateral Root Formation in Rapeseed

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    Carbon monoxide (CO), an odorless, tasteless and colorless gas, has recently proved to be an important bioactive or signal molecule in mammalian cells, with its effects mediated mainly by nitric oxide (NO). In the present report, we show that exogenous CO induces lateral root (LR) formation, an NO-dependent process. Administration of the CO donor hematin to rapeseed (Brassica napus L. Yangyou 6) seedlings for 3 days, dose-dependently promoted the total length and number of LRs. These responses were also seen following the application of gaseous CO aqueous solutions of different saturated concentrations. Furthermore, the actions of CO on seedlings were fully reversed when the CO scavenger hemoglobin (Hb)or the CO-specific synthetic inhibitor zinc protoporphyrin-Ⅸ (ZnPPIX) were added. Interestingly, depletion of endogenous NO using its specific scavenger 2-(4-carboxyphenyl)-4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide potassium salt (cPTIO)or the nitric oxide synthase (NOS) inhibitor NG-nitro-L-arginine methyl ester (L-NAME), led to the complete abolition of LR development, illustrating an important role for endogenous NO in the action of CO on LR formation. However, the or absence of ZnPPIX. Furthermore, using an anatomical approach combined with laser scanning confocal microscopy with the NO-specific fluorophore 4,5-diaminofluorescein diacetate, we observed that both hematin and SNP increased NO release compared with control samples and that the NO signal was mainly distributed in the LR primordia (LRP), especially after 36 h treatment. The LRP were found to have similar morphology in control, SNP- and hematin-treated seedlings.Similarly, the enhancement of the NO signal by CO at 36 h was differentially quenched by the addition of cPTIO, L-NAME,ZnPPIX and Hb. In contrast, the induction of NO caused by SNP was not affected by the application of ZnPPIX. Therefore,we further deduced that CO induces LR formation probably mediated by the NO/NOS pathway and NO may act

  20. Annual hydrogen, carbon monoxide and carbon dioxide concentrations and surface to air exchanges in a rural area (Québec, Canada)

    Science.gov (United States)

    Constant, Philippe; Poissant, Laurier; Villemur, Richard

    The industrialization and the demographic expansion have both influenced the biogeochemical cycle of hydrogen (H 2), carbon monoxide (CO) and carbon dioxide (CO 2). In the actual context, knowledge about the spatial distribution of the natural sources and sinks of these trace gases is then crucial to infer possible effects of climate and land use changes on their global budget. This article reports the H 2, CO and CO 2 concentrations and micrometeorological fluxes measured during 1 year in a rural area of the mixed wood ecozone of Canada. Land use represents a critical issue in the control of trace gas natural sources or sinks of that region, which is the most densely habited in Canada. On average, the site emitted CO 2 at a rate of 7.7 g m -2 d -1 and consumed H 2 and CO at 0.34 and 5.1 mg m -2 d -1, respectively. Temperature was the most important factor affecting the H 2 and CO surface to air exchanges. The strength of the soil sink was maximal at the end of the summer, while H 2 and CO emissions were observed at the snow-melting period. In winter, H 2 and CO depositions were attributed to their oxidation by photochemically active compounds within the snow cover. When soil temperature was above 10 °C, trace gas fluxes followed a well-defined diurnal cycle. H 2 and CO 2 deposition rates were positively correlated with H 2O fluxes, while CO followed the inverse trend. CO 2 diurnal variations resulted from a balance between photosynthesis and soil respiration, while some biotic and abiotic factors were proposed to explain the trend observed for H 2. In the case of CO, emissions originating from heat- and photo-induced reactions were involved in the attenuation in the strength of the soil sink during daytime. Measured fluxes were compared with the literature to show the relative importance of the rural areas in the studied trace gases budget.

  1. Enhanced acute anti-inflammatory effects of CORM-2-loaded nanoparticles via sustained carbon monoxide delivery.

    Science.gov (United States)

    Qureshi, Omer Salman; Zeb, Alam; Akram, Muhammad; Kim, Myung-Sic; Kang, Jong-Ho; Kim, Hoo-Seong; Majid, Arshad; Han, Inbo; Chang, Sun-Young; Bae, Ok-Nam; Kim, Jin-Ki

    2016-11-01

    The aim of this study was to enhance the anti-inflammatory effects of carbon monoxide (CO) via sustained release of CO from carbon monoxide-releasing molecule-2-loaded lipid nanoparticles (CORM-2-NPs). CORM-2-NPs were prepared by hot high pressure homogenization method using trilaurin as a solid lipid core and Tween 20/Span 20/Myrj S40 as surfactant mixture. The physicochemical properties of CORM-2-NPs were characterized and CO release from CORM-2-NPs was assessed by myoglobin assay. In vitro anti-inflammatory effects were evaluated by nitric oxide assay in lipopolysaccharide-stimulated RAW 264.7 macrophages. In vivo anti-inflammatory activity was investigated by measuring paw volumes and histological examination in carrageenan-induced rat paw edema. Spherical CORM-2-NPs were around 100nm with narrow particle size distribution. The sustained CO release from CORM-2-NPs was observed and the half-life of CO release increased up to 10 times compared with CORM-2 solution. CORM-2-NPs showed enhanced in vitro anti-inflammatory effects by inhibition of nitric oxide production. Edema volume in rat paw was significantly reduced after treatment with CORM-2-NPs. Taken together, CORM-2-NPs have a great potential for CO therapeutics against inflammation via sustained release of CO. Copyright © 2016 Elsevier B.V. All rights reserved.

  2. Carbon Monoxide (CO) Is a Novel Inhibitor of Connexin Hemichannels*

    Science.gov (United States)

    León-Paravic, Carmen G.; Figueroa, Vania A.; Guzmán, Diego J.; Valderrama, Carlos F.; Vallejos, Antonio A.; Fiori, Mariana C.; Altenberg, Guillermo A.; Reuss, Luis; Retamal, Mauricio A.

    2014-01-01

    Hemichannels (HCs) are hexamers of connexins that can form gap-junction channels at points of cell contacts or “free HCs” at non-contacting regions. HCs are involved in paracrine and autocrine cell signaling, and under pathological conditions may induce and/or accelerate cell death. Therefore, studies of HC regulation are of great significance. Nitric oxide affects the activity of Cx43 and Cx46 HCs, whereas carbon monoxide (CO), another gaseous transmitter, modulates the activity of several ion channels, but its effect on HCs has not been explored. We studied the effect of CO donors (CORMs) on Cx46 HCs expressed in Xenopus laevis oocytes using two-electrode voltage clamp and on Cx43 and Cx46 expressed in HeLa cells using a dye-uptake technique. CORM-2 inhibited Cx46 HC currents in a concentration-dependent manner. The C-terminal domain and intracellular Cys were not necessary for the inhibition. The effect of CORM-2 was not prevented by guanylyl-cyclase, protein kinase G, or thioredoxin inhibitors, and was not due to endocytosis of HCs. However, the effect of CORM-2 was reversed by reducing agents that act extracellularly. Additionally, CO inhibited dye uptake of HeLa cells expressing Cx43 or Cx46, and MCF-7 cells, which endogenously express Cx43 and Cx46. Because CORM-2 carbonylates Cx46 in vitro and induces conformational changes, a direct effect of that CO on Cx46 is possible. The inhibition of HCs could help to understand some of the biological actions of CO in physiological and pathological conditions. PMID:25384983

  3. Inhibition of cellular respiration by endogenously produced carbon monoxide.

    Science.gov (United States)

    D'Amico, Gabriela; Lam, Francis; Hagen, Thilo; Moncada, Salvador

    2006-06-01

    Endogenously produced nitric oxide (NO) interacts with mitochondrial cytochrome c oxidase, leading to inhibition of cellular respiration. This interaction has been shown to have important physiological and pathophysiological consequences. Exogenous carbon monoxide (CO) is also known to inhibit cytochrome c oxidase in vitro; however, it is not clear whether endogenously produced CO can inhibit cellular respiration and, if so, what the significance of this might be. In this study, we show that exogenous CO inhibits respiration in a moderate but persistent manner in HEK293 cells under ambient (21%) oxygen concentrations (K(i) = 1.44 microM). This effect of CO was increased (K(i) = 0.35 microM) by incubation in hypoxic conditions (1% oxygen). Endogenous CO, generated by HEK293 cells transfected with the inducible isoform of haem oxygenase (haem oxygenase-1; HO-1), also inhibited cellular respiration moderately (by 12%) and this was accompanied by inhibition (23%) of cytochrome c oxidase activity. When the cells were incubated in hypoxic conditions during HO-1 induction, the inhibitory effect of CO on cell respiration was markedly increased to 70%. Furthermore, endogenously produced CO was found to be responsible for the respiratory inhibition that occurs in RAW264.7 cells activated in hypoxic conditions with lipopolysaccharide and interferon-gamma, in the presence of N-(iminoethyl)-L-ornithine to prevent the synthesis of NO. Our results indicate that CO contributes significantly to the respiratory inhibition in activated cells, particularly under hypoxic conditions. Inhibition of cell respiration by endogenous CO through its interaction with cytochrome c oxidase might have an important role in inflammatory and hypoxic conditions.

  4. Measurements on high temperature fuel cells with carbon monoxide-containing fuel gases; Messungen an Hochtemperatur-Brennstoffzellen mit kohlenmonoxidhaltigen Brenngasen

    Energy Technology Data Exchange (ETDEWEB)

    Apfel, Holger

    2012-10-10

    In the present work the different power density of anode-supported high-temperature solid oxide fuel cells (ASC-SOFCs) were examined for carbon monoxide-containing fuels. In addition to wet hydrogen / carbon monoxide mixtures the cells were run with synthetic gas mixtures resembling the products of an autothermal reformer, and actual reformate generated by a 2 kW autothermal reformer. It was found that the power-voltage characteristics of an ASC depends primarily on the open circuit voltages of different gas mixtures, but is nearly independent of the hydrogen concentration of the fuel, although the reaction rates of other potential fuels within the gas mixture, namely carbon monoxide and methane, are much lower that the hydrogen reaction rate. The probable reason is that the main fuel for the electrochemical oxidation within the cell is hydrogen, while the nickel in the base layer of the anode acts as a reformer which replenishes the hydrogen by water reduction via carbon monoxide and methane oxidation.

  5. STUDY OF MnOx-PROMOTED Cu/γ-Al203 CATALYSTS FOR HYDROGENATION OF CARBON MONOXIDE

    Institute of Scientific and Technical Information of China (English)

    Qi Gongxin; Fei Jinhua; Hou Zhaoyin; Zheng Xiaoming

    2001-01-01

    γ-Alumina-supported copper-manganese oxide was prepared by impregnation and used for carbon monoxide hydrogenation. The Cu-MnOx/γ-Al2O3 catalysts exhibit high catalytic activity in CO hydrogenation, showing markedly enhanced catalytic activities due to the synergistic interaction between the copper and manganese oxide. The results of XRD indicated that the addition of manganese enhances the dispersion of CuO, retards the reduction of CuO and enhances the ability of H2-adsorption, which contribute to the activity of DME synthesis from syngas.

  6. Oral administration of lactulose: a novel therapy for acute carbon monoxide poisoning via increasing intestinal hydrogen production.

    Science.gov (United States)

    Fan, Dan-Feng; Hu, Hui-Jun; Sun, Xue-Jun; Meng, Xiang-En; Zhang, Yu; Pan, Shu-Yi

    2016-01-01

    It has been known that the pathophysiology of carbon monoxide (CO) poisoning is related to hypoxia, the increased production of reactive oxygen species (ROS) and oxidative stress. Studies have shown that the novel, safe and effective free radical scavenger, hydrogen, has neuroprotective effects in both acute CO poisoning and delayed neuropsychological sequelae in CO poisoning. Orally administered lactulose, which may be used by some intestinal bacteria as a food source to produce endogenous hydrogen, can ameliorate oxidative stress. Based on the available findings, we hypothesize that oral administration of lactulose may be a novel therapy for acute CO poisoning via increasing intestinal hydrogen production.

  7. One-step photochemical synthesis of permanent, nonleaching, ultrathin antimicrobial coatings for textiles and plastics.

    Science.gov (United States)

    Dhende, Vikram P; Samanta, Satyabrata; Jones, David M; Hardin, Ian R; Locklin, Jason

    2011-08-01

    Antimicrobial copolymers of hydrophobic N-alkyl and benzophenone containing polyethylenimines were synthesized from commercially available linear poly(2-ethyl-2-oxazoline), and covalently attached to surfaces of synthetic polymers, cotton, and modified silicon oxide using mild photo-cross-linking. Specifically, these polymers were applied to polypropylene, poly(vinyl chloride), polyethylene, cotton, and alkyl-coated oxide surfaces using solution casting or spray coating and then covalently cross-linked rendering permanent, nonleaching antimicrobial surfaces. The photochemical grafting of pendant benzophenones allows immobilization to any surface that contains a C-H bond. Incubating the modified materials with either Staphylococcus aureus or Escherichia coli demonstrated that the modified surfaces had substantial antimicrobial capacity against both Gram-positive and Gram-negative bacteria (>98% microbial death).

  8. Regional ozone pollution and key controlling factors of photochemical ozone production in Pearl River Delta during summer time

    Institute of Scientific and Technical Information of China (English)

    CHANG; ChihChung; CHOU; C.K.Charles; Andreas; Wahner

    2010-01-01

    An intensive field campaign including measurements from the environmental monitoring network and from two super sites took place in the Pearl River Delta region in summer 2006.Using routinely measured O3 and NOx concentrations,the spatial and temporal variation of O3 and of the total oxidant concentrations was characterized.According to the spatial variability of NO2/NO,the two super sites were found to be representative of polluted urban and downwind suburban conditions.In addition,both sites were located in high O3 regions.In-depth diagnostic of photochemical ozone production processes and their key controlling factors are achieved with an observation-based model(OBM) to gain regional perspectives.Budget analysis and sensitivity model runs show that aldehyde and HONO chemistry had significant impacts on local photochemical ozone production rates.The analysis of calculated Relative Incremental Reactivities shows that photochemical ozone production rates are mainly sensitive to anthropogenic hydrocarbons(HCs) in the polluted urban areas.In the suburban areas,sensitivity to nitrogen oxide(NO) concentrations dominated.Key anthropogenic HCs in both areas are alkenes and aromatics.Significant differences of ozone production efficiencies are identified between the urban and suburban regions,consistent with the OBM diagnosed results.

  9. Seasonal changes in photochemical properties of dissolved organic matter

    Science.gov (United States)

    Porcal, P.; Dillon, P. J.; Molot, L. A.

    2013-03-01

    The fate of dissolved organic matter (DOM) in lakes and streams is significantly affected by photochemical transformation of DOM. A series of laboratory photochemical experiments was conducted to describe long-term changes in photochemical properties of DOM. The stream samples used in this study originated from three different catchments on the southern-most part of the Boreal ecozone near Dorset, Ontario, Canada. A first-order kinetics equation was used to model photochemical degradation of DOM and the kinetic rate constant, K, was used as an indicator of photochemical properties of DOM. Highest Kwas observed in samples from the catchment dominated by coniferous forest while the lowest K was measured in the deciduous catchment. Kinetic rate constants from all three catchments showed a sinusoidal pattern during the hydrological year. K increased steadily during autumn and winter and decreased during spring and summer. The highest values were observed during spring melt events when DOM was flushed from terrestrial sources by high flows. The minimum rate constants were found in summer when discharge was lowest. DOM molecular weight and specific absorbance at 254 nm also exhibited annual cycles corresponding to the seasonal cycles of terrestrial organic matter but the relationships between these properties and K was probably affected by previous exposure to solar radiation during transit from the catchment as well as pH and iron.

  10. Hemeoxygenase-1 inhibits human myometrial contractility via carbon monoxide and is upregulated by progesterone during pregnancy.

    Science.gov (United States)

    Acevedo, C H; Ahmed, A

    1998-03-01

    Nitric oxide was proposed as an endogenous inhibitor of myometrial contractility during pregnancy. Carbon monoxide (CO) like nitric oxide increases cGMP and is generated during the degradation of heme to biliverdin IX by hemeoxygenases (HO). Here we report that the expression of both HO-1 (inducible) and HO-2 (constitutive) were > 15-fold higher in pregnant myometrium compared to nonpregnant myometrium (n = 4, P synthesis (n = 4, P tin protoporphyrin IX (20 microM). This study clearly demonstrates the expression of HO in the human myometrium and shows that its induction produces CO that limits uterine contractility in pregnant myometrium indicating a role for the HO-CO-cGMP pathway in the maintenance of the quiescent state of the uterus during pregnancy.

  11. A population-based exposure assessment methodology for carbon monoxide: Development of a carbon monoxide passive sampler and occupational dosimeter

    Energy Technology Data Exchange (ETDEWEB)

    Apte, M.G.

    1997-09-01

    Two devices, an occupational carbon monoxide (CO) dosimeter (LOCD), and an indoor air quality (IAQ) passive sampler were developed for use in population-based CO exposure assessment studies. CO exposure is a serious public health problem in the U.S., causing both morbidity and mortality (lifetime mortality risk approximately 10{sup -4}). Sparse data from population-based CO exposure assessments indicate that approximately 10% of the U.S. population is exposed to CO above the national ambient air quality standard. No CO exposure measurement technology is presently available for affordable population-based CO exposure assessment studies. The LOCD and IAQ Passive Sampler were tested in the laboratory and field. The palladium-molybdenum based CO sensor was designed into a compact diffusion tube sampler that can be worn. Time-weighted-average (TWA) CO exposure of the device is quantified by a simple spectrophotometric measurement. The LOCD and IAQ Passive Sampler were tested over an exposure range of 40 to 700 ppm-hours and 200 to 4200 ppm-hours, respectively. Both devices were capable of measuring precisely (relative standard deviation <20%), with low bias (<10%). The LOCD was screened for interferences by temperature, humidity, and organic and inorganic gases. Temperature effects were small in the range of 10{degrees}C to 30{degrees}C. Humidity effects were low between 20% and 90% RH. Ethylene (200 ppm) caused a positive interference and nitric oxide (50 ppm) caused a negative response without the presence of CO but not with CO.

  12. A population-based exposure assessment methodology for carbon monoxide: Development of a carbon monoxide passive sampler and occupational dosimeter

    Energy Technology Data Exchange (ETDEWEB)

    Apte, Michael G. [Univ. of California, Berkeley, CA (United States)

    1997-09-01

    Two devices, an occupational carbon monoxide (CO) dosimeter (LOCD), and an indoor air quality (IAQ) passive sampler were developed for use in population-based CO exposure assessment studies. CO exposure is a serious public health problem in the U.S., causing both morbidity and mortality (lifetime mortality risk approximately 10{sup -4}). Sparse data from population-based CO exposure assessments indicate that approximately 10% of the U.S. population is exposed to CO above the national ambient air quality standard. No CO exposure measurement technology is presently available for affordable population-based CO exposure assessment studies. The LOCD and IAQ Passive Sampler were tested in the laboratory and field. The palladium-molybdenum based CO sensor was designed into a compact diffusion tube sampler that can be worn. Time-weighted-average (TWA) CO exposure of the device is quantified by a simple spectrophotometric measurement. The LOCD and IAQ Passive Sampler were tested over an exposure range of 40 to 700 ppm-hours and 200 to 4200 ppm-hours, respectively. Both devices were capable of measuring precisely (relative standard deviation <20%), with low bias (<10%). The LOCD was screened for interferences by temperature, humidity, and organic and inorganic gases. Temperature effects were small in the range of 10°C to 30°C. Humidity effects were low between 20% and 90% RH. Ethylene (200 ppm) caused a positive interference and nitric oxide (50 ppm) caused a negative response without the presence of CO but not with CO.

  13. Carbon monoxide tolerant platinum electrocatalysts on niobium doped titania and carbon nanotube composite supports

    Science.gov (United States)

    Rigdon, William A.; Huang, Xinyu

    2014-12-01

    In the anode of electrochemical cells operating at low temperature, the hydrogen oxidation reaction is susceptible to poisoning from carbon monoxide (CO) which strongly adsorbs on platinum (Pt) catalysts and increases activation overpotential. Adsorbed CO is removed by oxidative processes such as electrochemical stripping, though cleaning can also cause corrosion. One approach to improve the tolerance of Pt is through alloying with less-noble metals, but the durability of alloyed electrocatalysts is a critical concern. Without sacrificing stability, tolerance can be improved by careful design of the support composition using metal oxides. The bifunctional mechanism is promoted at junctions of the catalyst and metal oxides used in the support. Stable metal oxides can also form strong interactions with catalysts, as is the case for platinum on titania (TiOx). In this study, niobium (Nb) serves as an electron donor dopant in titania. The transition metal oxides are joined to functionalized multi-wall carbon nanotube (CNT) supports in order to synthesize composite supports. Pt is then deposited to form electrocatalysts which are characterized before fabrication into anodes for tests as an electrochemical hydrogen pump. Comparisons are made between the control from Pt-CNT to Pt-TiOx-CNT and Pt-Ti0.9Nb0.1Ox-CNT in order to demonstrate advantages.

  14. Evidence for dissolved organic matter as the primary source and sink of photochemically produced hydroxyl radical in arctic surface waters.

    Science.gov (United States)

    Page, Sarah E; Logan, J Robert; Cory, Rose M; McNeill, Kristopher

    2014-04-01

    Hydroxyl radical (˙OH) is an indiscriminate oxidant that reacts at near-diffusion-controlled rates with organic carbon. Thus, while ˙OH is expected to be an important oxidant of dissolved organic matter (DOM) and other recalcitrant compounds, the role of ˙OH in the oxidation of these compounds in aquatic ecosystems is not well known due to the poorly constrained sources and sinks of ˙OH, especially in pristine (unpolluted) natural waters. We measured the rates of ˙OH formation and quenching across a range of surface waters in the Arctic varying in concentrations of expected sources and sinks of ˙OH. Photochemical formation of ˙OH was observed in all waters tested, with rates of formation ranging from 2.6 ± 0.6 to 900 ± 100 × 10(-12) M s(-1). Steady-state concentrations ranged from 2 ± 1 to 290 ± 60 × 10(-17) M, and overlapped with previously reported values in surface waters. While iron-mediated photo-Fenton reactions likely contributed to the observed ˙OH production, several lines of evidence suggest that DOM was the primary source and sink of photochemically produced ˙OH in pristine arctic surface waters. DOM from first-order or headwater streams was more efficient in producing ˙OH than what has previously been reported for DOM, and ˙OH formation decreased with increasing residence time of DOM in sunlit surface waters. Despite the ubiquitous formation of ˙OH in arctic surface waters observed in this study, photochemical ˙OH formation was estimated to contribute ≤4% to the observed photo-oxidation of DOM; however, key uncertainties in this estimate must be addressed before ruling out the role of ˙OH in the oxidation of DOM in these waters.

  15. High temperature thermodynamics and vaporization of stoichiometric titanium monoxide

    Energy Technology Data Exchange (ETDEWEB)

    Sheldon, R.I.; Gilles, P.W.

    1976-08-17

    Three vaporization experiments were performed on samples of nearly stoichiometric titanium monoxide. Two experiments were constant temperature experiments (1806/sup 0/K) designed to measure the equilibrium vapor pressures of Ti(g) and TiO(g). In one experiment titanium monoxide was vaporized from a tungsten Knudsen effusion cell; the vapor was collected on a water cooled quartz cap surrounding the cell; and the total amount of titanium deposited on the cap was analyzed colorimetrically. In the second constant temperature experiment (1806/sup 0/K) the vapor composition in equilibrium with nearly stoichiometric titanium monoxide was measured mass spectrometrically. The mass spectrometer results were used to apportion the total titanium collected in the first experiment to Ti(g) and TiO(g). In the third experiment the temperature dependence of the ions Ti/sup +/(48) and TiO(64) was measured spectrometrically. The results obtained in this work are compared with published thermodynamic properties of the titanium oxygen system, and indicate the standard free energy of formation of titanium monoxide obtained from the earliest calorimetric measurements yielded a result not negative enough and also oxygen pressures obtained by emf measurements for stoichiometric titanium monoxide at 1806/sup 0/K are high by a factor of 42.6. The present results are in good agreement with the thermodynamic properties reported in recently issued pages of the JANAF Thermochemical Tables.

  16. Kinetic analyses and mathematical modeling of primary photochemical and photoelectrochemical processes in plant photosystems.

    Science.gov (United States)

    Vredenberg, Wim

    2011-02-01

    In this paper the model and simulation of primary photochemical and photo-electrochemical reactions in dark-adapted intact plant leaves is presented. A descriptive algorithm has been derived from analyses of variable chlorophyll a fluorescence and P700 oxidation kinetics upon excitation with multi-turnover pulses (MTFs) of variable intensity and duration. These analyses have led to definition and formulation of rate equations that describe the sequence of primary linear electron transfer (LET) steps in photosystem II (PSII) and of cyclic electron transport (CET) in PSI. The model considers heterogeneity in PSII reaction centers (RCs) associated with the S-states of the OEC and incorporates in a dark-adapted state the presence of a 15-35% fraction of Q(B)-nonreducing RCs that probably is identical with the S₀ fraction. The fluorescence induction algorithm (FIA) in the 10 μs-1s excitation time range considers a photochemical O-J-D, a photo-electrochemical J-I and an I-P phase reflecting the response of the variable fluorescence to the electric trans-thylakoid potential generated by the proton pump fuelled by CET in PSI. The photochemical phase incorporates the kinetics associated with the double reduction of the acceptor pair of pheophytin (Phe) and plastoquinone Q(A) [PheQ(A)] in Q(B) nonreducing RCs and the associated doubling of the variable fluorescence, in agreement with the three-state trapping model (TSTM) of PS II. The decline in fluorescence emission during the so called SMT in the 1-100s excitation time range, known as the Kautsky curve, is shown to be associated with a substantial decrease of CET-powered proton efflux from the stroma into the chloroplast lumen through the ATPsynthase of the photosynthetic machinery.

  17. A Novel Method For Predicting Carbon Monoxide Apparent Quantum Yield Spectra in Coastal Water Using Remote Sensing Reflectance Data

    Science.gov (United States)

    Reader, H. E.; Miller, W. L.

    2010-12-01

    Photochemical oxidation of chromophoric dissolved organic matter (CDOM) is the major source of carbon monoxide to the surface ocean. Bacterial consumption and air-sea exchange comprise the two known sinks for CO in marine systems. Though the two loss terms are relatively efficient, CO remains supersaturated with respect to the atmosphere in the surface ocean. Global oceanic estimates of CO photoproduction range from 30-84Tg CO/year (Zafiriou 2003, Fichot and Miller 2010). The variation in estimates is largely due to the difficulty in predicting the efficiency of photoproduction (i.e. Apparent Quantum Yield; AQY). Though the AQY for CO photoproduction appears to be relatively constant, there is indication that terrestrially derived sources, such as those found in estuarine environments, produce CO more efficiently than marine derived sources (Ziolkowski 2000). Since variation among sources is likely in the global ocean, accurate assignment of AQY to variable water types is required to accurately predict CO photoproduction. Deriving the correct apparent quantum yield from remotely sensed data would lead to better predictions of large scale CO photoproduction from optical data. Thirty-eight (38) AQY spectra for CO photoproduction were determined by monthly sampling during spring tides in three dark water locations on the coast of Georgia, USA, from November 2008 to September 2009. Sapelo Sound, a marine dominated system, receives little to no freshwater input over the year, while Altamaha Sound drains the largest watershed in the state of Georgia, and has largely variably freshwater input. Doboy Sound, situated between Sapelo Sound and Altamaha Sound, is largely marine dominated, though in periods of high flow on the Altamaha River, receives some fresh water overflow. The coast of Georgia is dominated by Spartina alterniflora salt marshes, and thus also has a strong non-point source of terrestrially derived carbon. CO apparent quantum yields were determined by

  18. A Southern Hemisphere atmospheric history of carbon monoxide from South Pole firn air

    Science.gov (United States)

    Verhulst, K. R.; Aydin, M.; Novelli, P. C.; Holmes, C. D.; Prather, M. J.; Saltzman, E. S.

    2013-12-01

    Carbon monoxide (CO) is a reactive trace gas and is important to tropospheric photochemistry as a major sink of hydroxyl radicals (OH). Major sources of CO are fossil fuel combustion, linked mostly to automotive emissions, biomass burning, and oxidation of atmospheric methane. Understanding changes in carbon monoxide over the past century will improve our understanding of man's influence on the reactivity of the atmosphere. Little observational information is available about CO levels and emissions prior to the 1990s, particularly for the Southern Hemisphere. The NOAA global flask network provides the most complete instrumental record of CO, extending back to 1988. Annually averaged surface flask measurements suggest atmospheric CO levels at South Pole were relatively stable from 2004-2009 at about 51 nmol mol-1 [Novelli and Masarie, 2013]. In this study, a 20th century atmospheric history of CO is reconstructed from South Pole firn air measurements, using a 1-D firn air diffusion model. Firn air samples were collected in glass flasks from two adjacent holes drilled from the surface to 118 m at South Pole, Antarctica during the 2008/2009 field season and CO analysis was carried out by NOAA/CCG. Carbon monoxide levels increase from about 45 nmol mol-1 in the deepest firn sample at 116 m to 52 nmol mol-1 at 107 m, and remain constant at about 51-52 nmol mol-1 at shallower depths. Atmospheric histories based on the firn air reconstructions suggest that CO levels over Antarctica increased by roughly 40% (from about 36 to 50 nmol mol-1) between 1930-1990, at a rate of about 0.18 nmol mol-1 yr-1. Firn air and surface air results suggest the rate of CO increase at South Pole slowed considerably after 1990. The firn air-based atmospheric history is used to infer changes in Southern Hemisphere CO emissions over the 20th century.

  19. Approximate photochemical dynamics of azobenzene with reactive force fields

    Science.gov (United States)

    Li, Yan; Hartke, Bernd

    2013-12-01

    We have fitted reactive force fields of the ReaxFF type to the ground and first excited electronic states of azobenzene, using global parameter optimization by genetic algorithms. Upon coupling with a simple energy-gap transition probability model, this setup allows for completely force-field-based simulations of photochemical cis→trans- and trans→cis-isomerizations of azobenzene, with qualitatively acceptable quantum yields. This paves the way towards large-scale dynamics simulations of molecular machines, including bond breaking and formation (via the reactive force field) as well as photochemical engines (presented in this work).

  20. Photochemical preparation and application research of Au nanoparticles

    Institute of Scientific and Technical Information of China (English)

    DONG; Shou-an; SUN; Jia-lin

    2005-01-01

    Gold nanoparticles protected by organic small molecular compounds or macromolecule have attracted considerable attention and their preparation is one of hotspots in the nano-chemical material field due to their ongoing and potential applications in optics, electronics, catalysts and biosensors. In recent years there are many liquid phase chemistry methods to prepare monodispersed gold particles. Among them, the photochemical method is quite attractive because of its some important advantages for size-controlled synthesis of gold nanoparticles. Therefore, in this paper the recert progress of the photochemical preparing Au nanoparticle materials was briefly introduced and mainly emphasized authors' own works of this area.

  1. Approximate photochemical dynamics of azobenzene with reactive force fields.

    Science.gov (United States)

    Li, Yan; Hartke, Bernd

    2013-12-14

    We have fitted reactive force fields of the ReaxFF type to the ground and first excited electronic states of azobenzene, using global parameter optimization by genetic algorithms. Upon coupling with a simple energy-gap transition probability model, this setup allows for completely force-field-based simulations of photochemical cis→trans- and trans→cis-isomerizations of azobenzene, with qualitatively acceptable quantum yields. This paves the way towards large-scale dynamics simulations of molecular machines, including bond breaking and formation (via the reactive force field) as well as photochemical engines (presented in this work).

  2. The exploration of supramolecular systems and nanostructures by photochemical techniques

    CERN Document Server

    Ceroni, Paola

    2011-01-01

    ""The Exploration of Supramolecular Systems and Nanostructures by Photochemical Techniques"" provides a comprehensive view of the most commonly used photochemical and photophysical techniques and their applications to the study of supramolecular systems. Optical inputs are extremely powerful in the study of nanostructures since they can be used both to ""read"" the state of the system and to provide it energy to work. After a brief introduction to the realm of photochemistry, electronically excited state formation and the different pathways of excited state deactivation, the book focuses on th

  3. Ozone and carbon monoxide at the Ushuaia GAW-WMO global station

    Science.gov (United States)

    Adame, Jose; Cupeiro, Manuel; Yela, Margarita; Cuevas, Emilio; Carbajal, Gerardo

    2016-04-01

    Ozone and carbon monoxide have been investigated in the GAW-WMO station of Ushuaia (Argentina), using hourly values during five years (2010-2014). This work has been developed in the framework of HELADO (Halogens in the Antarctic atmosphere and its role in the Ozone distribution) project and under the collaboration between INTA (National Institute for Aerospace Technology - Spain), SMN (National Meteorological Service - Argentina) and AEMET (State Meteorological Agency - Spain). Meteorological features have been analyzed with in-situ observations and meteorological fields from ECMWF 0.5° as spatial resolution model. These fields have been applied to compute back trajectories with HYSPLIT model. Independently of season, mostly atmospheric flows coming from W-SW (South Pacific Ocean), theses westerlies winds are associated with low pressure systems; in addition with lower frequencies are collected winds from South (Antarctic Peninsula and Weddell Sea), polar easterlies. Hourly averages of surface (in-situ) ozone and CO levels were 20±7 and 71±45 ppb respectively, typical values of remote environments. A clear seasonal pattern has been obtained for surface ozone with monthly peaks in winter of 25 ppb and minimum in summer with 12 ppb; a similar behaviour is found for CO, 93 and 48 ppb for maximum and minimum values, respectively. A weak daily cycle has been obtained in both species, amplitude for ozone of 2-4 ppb and 13-20 ppb for CO. The seasonal levels behaviour for surface ozone is also observed in upper levels, approximately from surface up to 5 km. This result has been obtained from 139 ozone profiles launched in the studied period. Since the ozone precursors and carbon monoxide emissions are low in this area, the origin of the values observed could be in the atmospheric transport processes. As hypothesis to explain the behaviour observed, we suggest that in the warm season with solar radiation, the photochemical mechanisms are active, and the elimination

  4. PHOTOCHEMICAL REACTIONS OF FORMYLMETHYLFLAVIN AND RIBOFLAVIN

    Directory of Open Access Journals (Sweden)

    Tania Mirza

    2015-12-01

    Full Text Available Formylmethylflavin (FMF is a major intermediate product in the aerobic and anaerobic photolysis of riboflavin (RF and is highly sensitive to light and hydrolysis. It is more sensitive to light as compared to RF. FMF is further degraded into lumichrome (LC, carboxymethylflavin (CMF in acidic medium, and LC, CMF and lumiflavin (LF in alkaline medium. When FMF is exposed to light it is degraded in to LC and LF via a photoreduction and CMF through photooxidation pathways. In aerobic and anaerobic conditions, RF when exposed to light is excited to singlet state (1RF and from singlet to triplet state (3RF. This is followed by the conversion of 3RF into a semiquinone radical (RFH and this radical further disproportionate to form an oxidized RF and a cyclic intermediate, which is further oxidized to FMF and degradation products (LC, LF, CMF.

  5. Unification of catalytic water oxidation and oxygen reduction reactions: amorphous beat crystalline cobalt iron oxides.

    Science.gov (United States)

    Indra, Arindam; Menezes, Prashanth W; Sahraie, Nastaran Ranjbar; Bergmann, Arno; Das, Chittaranjan; Tallarida, Massimo; Schmeißer, Dieter; Strasser, Peter; Driess, Matthias

    2014-12-17

    Catalytic water splitting to hydrogen and oxygen is considered as one of the convenient routes for the sustainable energy conversion. Bifunctional catalysts for the electrocatalytic oxygen reduction reaction (ORR) and the oxygen evolution reaction (OER) are pivotal for the energy conversion and storage, and alternatively, the photochemical water oxidation in biomimetic fashion is also considered as the most useful way to convert solar energy into chemical energy. Here we present a facile solvothermal route to control the synthesis of amorphous and crystalline cobalt iron oxides by controlling the crystallinity of the materials with changing solvent and reaction time and further utilize these materials as multifunctional catalysts for the unification of photochemical and electrochemical water oxidation as well as for the oxygen reduction reaction. Notably, the amorphous cobalt iron oxide produces superior catalytic activity over the crystalline one under photochemical and electrochemical water oxidation and oxygen reduction conditions.

  6. [Massive poisoning with carbon monoxide: an update from a case].

    Science.gov (United States)

    Díaz, Mariano; Crapanzano, Gabriel; Cabrerizo, Silvia; Aichele, Cristina; Deurtiaga, Alejandra; Vallejos, Yamila

    2017-02-01

    Carbon monoxide is known as the "silent murderer" because it is a colorless and odorless gas. According to these characteristics, toxicity goes unnoticed which makes the diagnosis difficult. In most cases, the cold periods and group poisoning make suspect its presence because inappropriate heat both in home or public environments. Our goal is to inform about a mass carbon monoxide poisoning in a children's parties room using a combustion source installed, not for the purpose of heating, but as a supply of light (generator), emphasizing that it can occur in any time of the year.

  7. Structural and magnetic properties of mechanochemically synthesized nanocrystalline titanium monoxide

    Directory of Open Access Journals (Sweden)

    Barudžija Tanja

    2012-01-01

    Full Text Available Nano-sized titanium monoxide (TiO powder was prepared by mechanochemical synthesis. A mixture of commercial Ti and TiO2 (rutile powders with the molar ratio of 1:1 was milled in a planetary ball mill for 5, 10, 20, 30 and 60 min under argon atmosphere. The final single-phase titanium monoxide sample was characterized by X-ray diffraction (XRD, magnetic measurements using a superconducting quantum interference device magnetometer (SQUID and thermogravimetric analysis (TGA. The temperature dependency of the magnetic susceptibility is characterized by significant contribution of Pauli paramagnetism due to conduction electrons.

  8. Electro- and photochemical switching of dithienylethene self-assembled monolayers on gold electrodes

    DEFF Research Database (Denmark)

    Browne, W.R.; Kudernac, T.; Katsonis, N.

    2008-01-01

    The photochemical and electrochemical properties of self-assembled monolayers (SAM) of three structurally distinct hexahydro- and hexafluoro-dithienylcyclopentene-based photochromic switches on gold electrodes are reported. The photochemical and electrochemical switching between the open and closed...

  9. A Model Study of the Photochemical Fate of As(III in Paddy-Water

    Directory of Open Access Journals (Sweden)

    Luca Carena

    2017-03-01

    Full Text Available The APEX (Aqueous Photochemistry of Environmentally-occurring Xenobiotics software previously developed by one of us was used to model the photochemistry of As(III in paddy-field water, allowing a comparison with biotic processes. The model included key paddy-water variables, such as the shielding effect of the rice canopy on incident sunlight and its monthly variations, water pH, and the photochemical parameters of the chromophoric dissolved organic matter (CDOM occurring in paddy fields. The half-life times (t1/2 of As(III photooxidation to As(V would be ~20–30 days in May. In contrast, the photochemical oxidation of As(III would be much slower in June and July due to rice-canopy shading of radiation because of plant growth, despite higher sunlight irradiance. At pH < 8 the photooxidation of As(III would mainly be accounted for by reaction with transient species produced by irradiated CDOM (here represented by the excited triplet states 3CDOM*, neglecting the possibly more important reactions with poorly known species such as the phenoxy radicals and, to a lesser extent, with the hydroxyl radicals (HO•. However, the carbonate radicals (CO3•− could be key photooxidants at pH > 8.5 provided that the paddy-water 3CDOM* is sufficiently reactive toward the oxidation of CO32−. In particular, if paddy-water 3CDOM* oxidizes the carbonate anion with a second-order reaction rate constant near (or higher than 106 M−1·s−1, the photooxidation of As(III could be quite fast at pH > 8.5. Such pH conditions can be produced by elevated photosynthetic activity that consumes dissolved CO2.

  10. Efficient photochemical generation of peroxycarboxylic nitric anhydrides with ultraviolet light emitting diodes

    Directory of Open Access Journals (Sweden)

    N. D. Rider

    2015-01-01

    Full Text Available Photochemical sources of peroxycarboxylic nitric anhydrides (PANs are utilized in many atmospheric measurement techniques for calibration or to deliver an internal standard. Conventionally, such sources rely on phosphor-coated low-pressure mercury (Hg lamps to generate the UV light necessary to photo-dissociate a dialkyl ketone (usually acetone in the presence of a calibrated amount of nitric oxide (NO and oxygen (O2. In this manuscript, a photochemical PAN source in which the Hg lamp has been replaced by arrays of ultraviolet light-emitting diodes (UV-LEDs is described. The output of the UV-LED source was analyzed by gas chromatography (PAN-GC and thermal dissociation cavity ring-down spectroscopy (TD-CRDS. Using acetone, diethyl ketone (DIEK, diisopropyl ketone (DIPK, or di-n-propyl ketone (DNPK, respectively, the source produces peroxyacetic (PAN, peroxypropionic (PPN, peroxyisobutanoic (PiBN, or peroxy-n-butanoic nitric anhydride (PnBN from NO in high yield (> 90%. Box model simulations with a subset of the Master Chemical Mechanism (MCM were carried out to rationalize products yields and to identify side products. The use of UV-LED arrays offers many advantages over conventional Hg lamp setups, including greater light output over a narrower wavelength range, lower power consumption, and minimal generation of heat.

  11. Photochemical decomposition of perfluorooctanoic acid mediated by iron in strongly acidic conditions.

    Science.gov (United States)

    Ohno, Masaki; Ito, Masataka; Ohkura, Ryouichi; Mino A, Esteban R; Kose, Tomohiro; Okuda, Tetsuji; Nakai, Satoshi; Kawata, Kuniaki; Nishijima, Wataru

    2014-03-15

    The performance of a ferric ion mediated photochemical process for perfluorooctanoic acid (PFOA) decomposition in strongly acidic conditions of pH 2.0 was evaluated in comparison with those in weakly acidic conditions, pH 3.7 or pH 5.0, based on iron species composition and ferric ion regeneration. Complete decomposition of PFOA under UV irradiation was confirmed at pH 2.0, whereas perfluoroheptanoic acid (PFHpA) and other intermediates were accumulated in weakly acidic conditions. Iron states at each pH were evaluated using a chemical equilibrium model, Visual MINTEQ. The main iron species at pH 2.0 is Fe(3+) ion. Although Fe(3+) ion is consumed and is transformed to Fe(2+) ion by photochemical decomposition of PFOA and its intermediates, the produced Fe(2+) ion will change to Fe(3+) ion to restore chemical equilibrium. Continuous decomposition will occur at pH 2.0. However, half of the iron cannot be dissolved at pH 3.7. The main species of dissolved iron is Fe(OH)(2+). At pH 3.7 or higher pH, Fe(3+) ion will only be produced from the oxidation of Fe(2+) ion by hydroxyl radical produced by Fe(OH)(2+) under UV irradiation. These different mechanisms of Fe(3+) regeneration that prevail in strongly and weakly acidic conditions will engender different performances of the ferric ion.

  12. Novel pathway for N1-acetyl-5-methoxykynuramine: UVB-induced liberation of carbon monoxide from precursor N1-acetyl-N2-formyl-5-methoxykynuramine.

    Science.gov (United States)

    Seever, Katinka; Hardeland, Rüdiger

    2008-05-01

    Irradiation of the melatonin metabolite N(1)-acetyl-N(2)-formyl-5-methoxykynuramine (AFMK) with UV light of 254 nm causes the release of carbon monoxide (CO) and, thus, deformylation to N(1)-acetyl-5-methoxykynuramine (AMK). Liberation of CO was demonstrated by reduction of PdCl(2) to metallic palladium, under avoidance of actions by other reductants. Photochemical AMK formation was not due to UV-induced hydroxyl radicals, because the reaction also took place with high efficiency in ethanol and 2-propanol. Moreover, AMK was generated from AFMK by UVB on a dry thin layer chromatographic plate. Although AMK seems to be the major primary product generated by UVB radiation, prolonged exposure of AFMK led to various other products, especially formed by destruction of AMK, as shown by irradiation of this latter compound. With regard to the demonstration of melatonin in skin and substantial amounts of AFMK in keratinocytes, these findings may be of dermatologic relevance.

  13. Characteristics of autoignited laminar lifted flames in heated coflow jets of carbon monoxide/hydrogen mixtures

    KAUST Repository

    Choi, Byungchul

    2012-06-01

    The characteristics of autoignited lifted flames in laminar jets of carbon monoxide/hydrogen fuels have been investigated experimentally in heated coflow air. In result, as the jet velocity increased, the blowoff was directly occurred from the nozzle-attached flame without experiencing a stabilized lifted flame, in the non-autoignited regime. In the autoignited regime, the autoignited lifted flame of carbon monoxide diluted by nitrogen was affected by the water vapor content in the compressed air oxidizer, as evidenced by the variation of the ignition delay time estimated by numerical calculation. In particular, in the autoignition regime at low temperatures with added hydrogen, the liftoff height of the autoignited lifted flames decreased and then increased as the jet velocity increased. Based on the mechanism in which the autoignited laminar lifted flame is stabilized by ignition delay time, the liftoff height can be influenced not only by the heat loss, but also by the preferential diffusion between momentum and mass diffusion in fuel jets during the autoignition process. © 2012 The Korean Society of Mechanical Engineers.

  14. Photochemical control of the distribution of Venusian water

    Science.gov (United States)

    Parkinson, Christopher D.; Gao, Peter; Esposito, Larry; Yung, Yuk; Bougher, Stephen; Hirtzig, Mathieu

    2015-08-01

    We use the JPL/Caltech 1-D photochemical model to solve continuity diffusion equation for atmospheric constituent abundances and total number density as a function of radial distance from the planet Venus. Photochemistry of the Venus atmosphere from 58 to 112 km is modeled using an updated and expanded chemical scheme (Zhang et al., 2010, 2012), guided by the results of recent observations and we mainly follow these references in our choice of boundary conditions for 40 species. We model water between 10 and 35 ppm at our 58 km lower boundary using an SO2 mixing ratio of 25 ppm as our nominal reference value. We then vary the SO2 mixing ratio at the lower boundary between 5 and 75 ppm holding water mixing ratio of 18 ppm at the lower boundary and finding that it can control the water distribution at higher altitudes. SO2 and H2O can regulate each other via formation of H2SO4. In regions of high mixing ratios of SO2 there exists a "runaway effect" such that SO2 gets oxidized to SO3, which quickly soaks up H2O causing a major depletion of water between 70 and 100 km. Eddy diffusion sensitivity studies performed characterizing variability due to mixing that show less of an effect than varying the lower boundary mixing ratio value. However, calculations using our nominal eddy diffusion profile multiplied and divided by a factor of four can give an order of magnitude maximum difference in the SO2 mixing ratio and a factor of a few difference in the H2O mixing ratio when compared with the respective nominal mixing ratio for these two species. In addition to explaining some of the observed variability in SO2 and H2O on Venus, our work also sheds light on the observations of dark and bright contrasts at the Venus cloud tops observed in an ultraviolet spectrum. Our calculations produce results in agreement with the SOIR Venus Express results of 1 ppm at 70-90 km (Bertaux et al., 2007) by using an SO2 mixing ratio of 25 ppm SO2 and 18 ppm water as our nominal reference

  15. Photochemical fate of pharmaceuticals in the environment: cimetidine and ranitidine.

    Science.gov (United States)

    Latch, Douglas E; Stender, Brian L; Packer, Jennifer L; Arnold, William A; McNeill, Kristopher

    2003-08-01

    The photochemical fates of the histamine H2-receptor antagonists cimetidine and ranitidine were studied. Each of the two environmentally relevant pharmaceuticals displayed high rates of reaction with both singlet oxygen (1O2, O2(1delta(g))) and hydroxyl radical (*OH), two transient oxidants formed in sunlit natural waters. For cimetidine, the bimolecular rate constant for reaction with *OH in water is 6.5 +/- 0.5 x 10(9) M(-1) s(-1). Over the pH range 4-10, cimetidine reacts with 1O2 with bimolecular rate constants ranging from 3.3 +/- 0.3 x 10(6) M(-1) s(-1) at low pH to 2.5 +/- 0.2 x 10(8) M(-1) s(-1) in alkaline solutions. The bimolecular rate constants for ranitidine reacting with 1O2 in water ranges from 1.6 +/- 0.2 x 10(7) M(-1) s(-1) at pH 6-6.4 +/- 0.2 x 10(7) M(-1) s(-1) at pH 10. Reaction of ranitidine hydrochloride with *OH proceeds with a rate constant of 1.5 +/- 0.2 x 10(10) M(-1) s(-1). Ranitidine was also degraded in direct photolysis experiments with a half-life of 35 min under noon summertime sunlight at 45 degrees latitude, while cimetidine was shown to be resistant to direct photolysis. The results of these experiments, combined with the expected steady-state near surface concentrations of 1O2 and *OH, indicate that photooxidation mediated by 1O2 is the likely degradation pathway for cimetidine in most natural waters, and photodegradation by direct photolysis is expected to be the major pathway for ranitidine, with some degradation caused by 1O2. These predictions were verified in studies using Mississippi River water. Model compounds were analyzed by laser flash photolysis experiments to assess which functionalities within ranitidine and cimetidine are most susceptible to singlet-oxygenation and direct photolysis. The heterocyclic moieties of the pharmaceuticals were clearly implicated as the sites of reaction with 1O2, as evidenced by the high relative rate constants of the furan and imidazole models. The nitroacetamidine portion of ranitidine

  16. Photochemical processes and ozone production in Finnish conditions

    Energy Technology Data Exchange (ETDEWEB)

    Laurila, T.; Hakola, H. [Finnish Meteorological Inst., Helsinki (Finland). Air Quality Dept.

    1996-12-31

    Photochemical ozone production is observed in March-September. Highest ozone concentrations and production efficiencies are observed in spring in the northern parts and in summer in the southern parts of the country. VOC concentrations are relatively low compared to continental areas in general. During the growing season a substantial part of the total reactive mass of VOCs is of biogenic origin. Large forest areas absorb ozone substantially, decreasing the ambient ozone concentrations in central and northern parts of Finland where long-range transport of ozone is relatively important compared to local production. The aim of the work conducted at Finnish Meteorological Institute has been to characterise concentrations of photochemically active species in the boundary layer and their photochemical formation and deposition including the effects on vegetation. Also interactions between the boundary layer and free troposphere of ozone have been studied. In the future, fluxes of both biogenic species and air pollutants will be measured and the models will be further developed so that the photochemical and micrometeorological processes could be better understood

  17. Photochemical Process Modeling and Analysis of Ozone Generation

    Institute of Scientific and Technical Information of China (English)

    王冰; 邱彤; 陈丙珍

    2014-01-01

    Air pollution in modern city and industrial zones has become a serious public concern in recent years in China. Significance of air quality assessment and emission control strategy design is increasing. Most studies in China focus on particulate matter (PM), especially PM2.5, while few account for photochemical secondary air pol-lutions represented by ozone (O3). In this paper, a procedure for air quality simulation with comprehensive air quality model with extensions (CAMx) is demonstrated for studying the photochemical process and ozone generation in the troposphere. As a case study, the CAMx photochemical grid model is used to model ozone over southern part of Beijing city in winter, 2011. The input parameters to CAMx include emission sources, meteorology field data, terrain definition, photolysis status, initial and boundary conditions. The simulation results are verified by theoretical analysis of the ozone generation tendency. The simulated variation tendency of domain-wide average value of hourly ozone concentration coincides reasonably well with the theoretical analysis on the atmospheric photochemical process, demonstrating the effectiveness of the procedure. An integrated model system that cooperates with CAMx will be established in our future work.

  18. Packed bed reactor for photochemical .sup.196 Hg isotope separation

    Science.gov (United States)

    Grossman, Mark W.; Speer, Richard

    1992-01-01

    Straight tubes and randomly oriented pieces of tubing having been employed in a photochemical mercury enrichment reactor and have been found to improve the enrichment factor (E) and utilization (U) compared to a non-packed reactor. One preferred embodiment of this system uses a moving bed (via gravity) for random packing.

  19. Photochemical Copper Coating on 3D Printed Thermoplastics.

    Science.gov (United States)

    Yung, Winco K C; Sun, Bo; Huang, Junfeng; Jin, Yingdi; Meng, Zhengong; Choy, Hang Shan; Cai, Zhixiang; Li, Guijun; Ho, Cheuk Lam; Yang, Jinlong; Wong, Wai Yeung

    2016-08-09

    3D printing using thermoplastics has become very popular in recent years, however, it is challenging to provide a metal coating on 3D objects without using specialized and expensive tools. Herein, a novel acrylic paint containing malachite for coating on 3D printed objects is introduced, which can be transformed to copper via one-step laser treatment. The malachite containing pigment can be used as a commercial acrylic paint, which can be brushed onto 3D printed objects. The material properties and photochemical transformation processes have been comprehensively studied. The underlying physics of the photochemical synthesis of copper was characterized using density functional theory calculations. After laser treatment, the surface coating of the 3D printed objects was transformed to copper, which was experimentally characterized by XRD. 3D printed prototypes, including model of the Statue of Liberty covered with a copper surface coating and a robotic hand with copper interconnections, are demonstrated using this painting method. This composite material can provide a novel solution for coating metals on 3D printed objects. The photochemical reduction analysis indicates that the copper rust in malachite form can be remotely and photo-chemically reduced to pure copper with sufficient photon energy.

  20. Photochemical Copper Coating on 3D Printed Thermoplastics

    Science.gov (United States)

    Yung, Winco K. C.; Sun, Bo; Huang, Junfeng; Jin, Yingdi; Meng, Zhengong; Choy, Hang Shan; Cai, Zhixiang; Li, Guijun; Ho, Cheuk Lam; Yang, Jinlong; Wong, Wai Yeung

    2016-01-01

    3D printing using thermoplastics has become very popular in recent years, however, it is challenging to provide a metal coating on 3D objects without using specialized and expensive tools. Herein, a novel acrylic paint containing malachite for coating on 3D printed objects is introduced, which can be transformed to copper via one-step laser treatment. The malachite containing pigment can be used as a commercial acrylic paint, which can be brushed onto 3D printed objects. The material properties and photochemical transformation processes have been comprehensively studied. The underlying physics of the photochemical synthesis of copper was characterized using density functional theory calculations. After laser treatment, the surface coating of the 3D printed objects was transformed to copper, which was experimentally characterized by XRD. 3D printed prototypes, including model of the Statue of Liberty covered with a copper surface coating and a robotic hand with copper interconnections, are demonstrated using this painting method. This composite material can provide a novel solution for coating metals on 3D printed objects. The photochemical reduction analysis indicates that the copper rust in malachite form can be remotely and photo-chemically reduced to pure copper with sufficient photon energy. PMID:27501761

  1. Photochemical Copper Coating on 3D Printed Thermoplastics

    Science.gov (United States)

    Yung, Winco K. C.; Sun, Bo; Huang, Junfeng; Jin, Yingdi; Meng, Zhengong; Choy, Hang Shan; Cai, Zhixiang; Li, Guijun; Ho, Cheuk Lam; Yang, Jinlong; Wong, Wai Yeung

    2016-08-01

    3D printing using thermoplastics has become very popular in recent years, however, it is challenging to provide a metal coating on 3D objects without using specialized and expensive tools. Herein, a novel acrylic paint containing malachite for coating on 3D printed objects is introduced, which can be transformed to copper via one-step laser treatment. The malachite containing pigment can be used as a commercial acrylic paint, which can be brushed onto 3D printed objects. The material properties and photochemical transformation processes have been comprehensively studied. The underlying physics of the photochemical synthesis of copper was characterized using density functional theory calculations. After laser treatment, the surface coating of the 3D printed objects was transformed to copper, which was experimentally characterized by XRD. 3D printed prototypes, including model of the Statue of Liberty covered with a copper surface coating and a robotic hand with copper interconnections, are demonstrated using this painting method. This composite material can provide a novel solution for coating metals on 3D printed objects. The photochemical reduction analysis indicates that the copper rust in malachite form can be remotely and photo-chemically reduced to pure copper with sufficient photon energy.

  2. Electrochemical and Photochemical Treatment of Aqueous Waste Streams

    Science.gov (United States)

    1996-01-01

    PAGES 6 Aerogel, Electrochemical treatment, Photochemical waste treatment, SERDP 16. PRICE CODE N/A 17. SECURITY CLASSIFICATION 18. SECURITY 19...Lawrence Livermore National Laboratory 7000 East Avenue Livermore, California 94550 (510)423-6574 ABSTRACT from sea water and 0.1 M KNO3 . This electrolytic

  3. Nonstationary heating during VUV photochemical ablation of polymers

    Science.gov (United States)

    Bityurin, N.; Castex, M. C.

    According to a previously developed pure photochemical model of VUV laser ablation of polymers, the velocity of ablation front is proportional to surface intensity, and a stationary value of the surface temperature does not depend on laser intensity. Previous estimations show, however, that this stationary surface temperature could be too high to be relevant to the photochemical mechanism. This raises a question of whether the stationary value of the surface temperature can be achieved for a given time shape of light intensity coming to the surface irradiated by a laser pulse of high enough fluence. The intensity time shape is connected not only with the time shape of a laser pulse but also with screening of laser radiation by the plume. This problem is discussed in the present communication. Specifically, it is shown that with a hyperbolic surface intensity time shape, heat diffusion can successfully compete with laser heating decreasing maximum surface temperature compared to its stationary value. The hyperbolic surface laser intensity corresponds to a rectangular laser pulse screened by plume during the photochemical ablation. This allows one to estimate that the photochemical model for a multiple-pulse VUV laser ablation with a high plume extinction coefficient is self-consistent even for a high value of stationary temperature and for high enough laser fluences.

  4. Investigation of isoprene oxidation in the atmosphere simulation chamber SAPHIR at low NO concentrations

    Science.gov (United States)

    Fuchs, H.; Rohrer, F.; Hofzumahaus, A.; Bohn, B.; Brauers, T.; Dorn, H.; Häseler, R.; Holland, F.; Li, X.; Lu, K.; Nehr, S.; Tillmann, R.; Wahner, A.

    2012-12-01

    During recent field campaigns, hydroxyl radical (OH) concentrations that were measured by laser-induced fluorescence spectroscopy (LIF) were up to a factor of ten larger than predicted by current chemical models for conditions of high OH reactivity and low nitrogen monoxide (NO) concentrations. These discrepancies were observed in the Pearl-River-Delta, China, which is an urban-influenced rural area, in rainforests, and forested areas in North America and Europe. Isoprene contributed significantly to the total OH reactivity in these field studies, so that potential explanations for the missing OH focused on new reaction pathways in the isoprene degradation mechanism. These pathways regenerate OH without oxidation of NO and thus without ozone production. In summer 2011, a series of experiments was carried out in the atmosphere simulation chamber SAPHIR in Juelich, Germany, in order to investigate the photochemical degradation of isoprene at low NO concentrations (NOSAPHIR by established chemical models like the Master Chemical Mechanism (MCM). Moreover, OH concentration measurements of two independent instruments (LIF and DOAS) agreed during all chamber experiments. Here, we present the results of the experiments and compare measurements with model predictions using the MCM. Furthermore, the validity of newly proposed reaction pathways in the isoprene degradation is evaluated by comparison with observations.

  5. The Effects of Low Level Prenatal Carbon Monoxide on Neocortical Development

    Science.gov (United States)

    2010-06-02

    378.1958). Ginsberg MD, Myers RE (Fetal brain damage following maternal carbon monoxide intoxication: an experimental study. Acta obstetricia et...monoxide production and blood loss at delivery. Acta obstetricia et gynecologica Scandinavica 48:362-370.1969). Longo LD (Carbon monoxide in the

  6. Correlation between catalytic activity of supported gold catalysts for carbon monoxide oxidation and metal-oxygen binding energy of the support metal oxides%负载金催化剂上CO氧化反应活性与金属氧化物载体中金属-氧结合能之间的关系

    Institute of Scientific and Technical Information of China (English)

    Takashi Fujita; Masanori Horikawa; Takashi Takei; Toru Murayama; Masatake Haruta

    2016-01-01

    The effect of a wide variety of metal oxide (MOx) supports has been discussed for CO oxidation on nanoparticulate gold catalysts. By using typical co‐precipitation and deposition–precipitation methods and under identical calcination conditions, supported gold catalysts were prepared on a wide variety of MOx supports, and the temperature for 50%conversion was measured to qualita‐tively evaluate the catalytic activities of these simple MOx and supported Au catalysts. Furthermore, the difference in these temperatures for the simple MOx compared to the supported Au catalysts is plotted against the metal–oxygen binding energies of the support MOx. A clear volcano‐like correla‐tion between the temperature difference and the metal–oxygen binding energies is observed. This correlation suggests that the use of MOx with appropriate metal–oxygen binding energies (300–500 kJ/atom O) greatly improves the catalytic activity of MOx by the deposition of Au NPs.%讨论了金属氧化物载体(MOx)对其负载纳米金催化剂(Au/MOx)上CO氧化反应的影响。采用典型的共沉淀法和沉积-沉淀法在完全相同的焙烧条件下制备了一系列MOx负载金催化剂,以CO氧化转化50%时的反应温度(T1/2)定量评价了MOx载体和Au/MOx催化剂的催化活性。进一步将MOx载体与相应Au/MOx催化剂的T1/2值之差对MOx载体的金属-氧结合能做曲线进行关联,发现二者呈明显的火山型关系。这一结果表明,采用具有适当金属-氧结合能(300–500 atom O)的MOx可大大提高沉积于其上的Au纳米颗粒的催化活性。

  7. SOFT X-RAY IRRADIATION OF PURE CARBON MONOXIDE INTERSTELLAR ICE ANALOGUES

    Energy Technology Data Exchange (ETDEWEB)

    Ciaravella, A.; Candia, R.; Collura, A. [INAF-Osservatorio Astronomico di Palermo, P.za Parlamento 1, 90134 Palermo (Italy); Jimenez-Escobar, A.; Munoz Caro, G. M. [Centro de Astrobiologia (CSIC-INTA), Carretera de Ajalvir, km 4, Torrejon de Ardoz, 28850 Madrid (Spain); Cecchi-Pestellini, C. [INAF-Osservatorio Astronomico di Cagliari, Strada n.54, Loc. Poggio dei Pini, I-09012 Capoterra (Italy); Giarrusso, S. [INAF-Istituto di Astrofisica Spaziale e Fisica Cosmica, Via U. La Malfa 153, I-90146 Palermo (Italy); Barbera, M., E-mail: aciaravella@astropa.unipa.it [Dipartimento di Scienze Fisiche and Astronomiche, Universita di Palermo, Sezione di Astronomia, Piazza del Parlamento 1, I-90134 Palermo (Italy)

    2012-02-10

    There is an increasing evidence for the existence of large organic molecules in the interstellar and circumstellar medium. Very few among such species are readily formed in conventional gas-phase chemistry under typical conditions of interstellar clouds. Attention has therefore focused on interstellar ices as a potential source of these relatively complex species. Laboratory experiments show that irradiation of interstellar ice analogues by fast particles or ultraviolet radiation can induce significant chemical complexity. However, stars are sources of intense X-rays at almost every stage of their formation and evolution. Such radiation may thus provide chemical changes in regions where ultraviolet radiation is severely inhibited. After H{sub 2}O, CO is often the most abundant component of icy grain mantles in dense interstellar clouds and circumstellar disks. In this work we present irradiation of a pure carbon monoxide ice using a soft X-ray spectrum peaked at 0.3 keV. Analysis of irradiated samples shows formation of CO{sub 2}, C{sub 2}O, C{sub 3}O{sub 2}, C{sub 3}, C{sub 4}O, and CO{sub 3}/C{sub 5}. Comparison of X-rays and ultraviolet irradiation experiments, of the same energy dose, shows that X-rays are more efficient than ultraviolet radiation in producing new species. With the exception of CO{sub 2}, X-ray photolysis induces formation of a larger number of products with higher abundances, e.g., C{sub 3}O{sub 2} column density is about one order of magnitude higher in the X-ray experiment. To our knowledge this is the first report on X-ray photolysis of CO ices. The present results show that X-ray irradiation represents an efficient photo-chemical way to convert simple ices to more complex species.

  8. On the relationship between acetone and carbon monoxide in different air masses

    Directory of Open Access Journals (Sweden)

    M. de Reus

    2003-01-01

    Full Text Available Carbon monoxide and acetone measurements are presented for five aircraft measurement campaigns at mid-latitudes, polar and tropical regions in the northern hemisphere. Throughout all campaigns, free tropospheric air masses, which were influenced by anthropogenic emissions, showed a similar linear relation between acetone and CO, with a slope of 21-25 pptv acetone/ppbv CO. Measurements in the anthropogenically influenced marine boundary layer revealed a slope of 13-16 pptv acetone/ppbv CO. The different slopes observed in the marine boundary layer and the free troposphere indicate that acetone is emitted by the ocean in relatively clean air masses and taken up by the ocean in polluted air masses. In the lowermost stratosphere, a good correlation between acetone and CO was observed as well, however, with a much smaller slope (~5 pptv acetone/ppbv CO compared to the troposphere. This is caused by the longer photochemical lifetime of CO compared to acetone in the lower stratosphere, due to the increasing photolytic loss of acetone and the decreasing OH concentration with altitude. No significant correlation between acetone and CO was observed over the tropical rain forest due to the large direct and indirect biogenic emissions of acetone. The common slopes of the linear acetone-CO relation in various layers of the atmosphere, during five field experiments, makes them useful for model calculations. Often a single observation of the acetone-CO correlation, determined from stratospheric measurements, has been used in box model applications. This study shows that different slopes have to be considered for marine boundary layer, free tropospheric and stratospheric air masses, and that the acetone-CO relation cannot be used for air masses which are strongly influenced by biogenic emissions.

  9. The Oxides of Nitrogen in Air Pollution.

    Science.gov (United States)

    California State Air Resources Board, Sacramento.

    Research on the health effects of oxides of nitrogen and on the role of oxides of nitrogen in producing photochemical smog effects is presented in this report. Prepared by the California State Department of Public Health at the request of the State Legislature, it gives a comprehensive review of available information, as well as the need for air…

  10. Snowmelt onset hinders bromine monoxide heterogeneous recycling in the Arctic

    Science.gov (United States)

    Burd, Justine A.; Peterson, Peter K.; Nghiem, Son V.; Perovich, Don K.; Simpson, William R.

    2017-08-01

    Reactive bromine radicals (bromine atoms, Br, and bromine monoxide, BrO) deplete ozone and alter tropospheric oxidation chemistry during the Arctic springtime (February-June). As spring transitions to summer (May-June) and snow begins to melt, reactive bromine events cease and BrO becomes low in summer. In this study, we explore the relationship between the end of the reactive bromine season and snowmelt timing. BrO was measured by Multi-AXis Differential Optical Absorption Spectrometer at Utqiaġvik (Barrow), AK, from 2012 to 2016 and on drifting buoys deployed in Arctic sea ice from 2011 to 2016, a total of 13 site and year combinations. The BrO seasonal end date (SED) was objectively determined and was compared to surface-air-temperature-derived melt onset date (MOD). The SED was highly correlated with the MOD (N = 13, R2 = 0.983, RMS = 1.9 days), and BrO is only observed at subfreezing temperatures. In subsets of these sites and years where ancillary data were available, we observed that snowpack depth reduced and rain precipitation occurred within a few days of the SED. These data are consistent with snowpack melting hindering BrO recycling, which is necessary to maintain enhanced BrO concentrations. With a projected warmer Arctic, a shift to earlier snowmelt seasons could alter the timing and role of halogen chemical reactions in the Arctic with impacts on ozone depletion and mercury deposition.Plain Language SummaryReactive bromine events in the Arctic are common in spring and deplete ozone and cause mercury deposition. These events are affected by snow and ice, which are changing in the Arctic; therefore, we need to understand how environmental conditions affect reactive bromine chemistry. We find that the reactive bromine season ends when snowpack begins to melt. Through these full seasonal observations, we find that reactive bromine events occur to warmer temperatures than previously reported, with 0°C being the observed threshold above which reactive

  11. Carbon Monoxide Poisoning - Multiple Languages: MedlinePlus

    Science.gov (United States)

    ... sharing features on this page, please enable JavaScript. Amharic (amarunya) Arabic (العربية) Chinese - Traditional (繁體中文) French (français) ... Kiswahili) Tagalog (Tagalog) Tigrinya (tigrinya) Vietnamese (Tiếng Việt) Amharic (amarunya) Prevention Guidelines: You Can Prevent Carbon Monoxide ...

  12. Pathways and bioenergetics of anaerobic carbon monoxide fermentation

    NARCIS (Netherlands)

    Diender, Martijn; Stams, Fons; Machado de Sousa, Diana

    2015-01-01

    Carbon monoxide can act as a substrate for different modes of fermentative anaerobic metabolism. The trait of utilizing CO is spread among a diverse group of microorganisms, including members of bacteria as well as archaea. Over the last decade this metabolism has gained interest due to the poten

  13. UV-induced carbon monoxide emission from living vegetation

    DEFF Research Database (Denmark)

    Bruhn, Dan; Albert, Kristian Rost; Mikkelsen, Teis Nørgaard

    2013-01-01

    The global burden of carbon monoxide (CO) is rather uncertain. In this paper we address the potential for UV-induced CO emission by living terrestrial vegetation surfaces. Real-time measurements of CO concentrations were made with a cavity enhanced laser spectrometer connected in closed loop...

  14. Study on Response Time of SPE Carbon Monoxide Sensor

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    The influence of structural design and the parameters of the working electrode on the response time of a solid polymer electrolyte (SPE) carbon monoxide sensor has been studied. Results show that the response time is mainly determined by the RC time constant of the catalyst layer and also related with the working electrode potential.

  15. Carbon monoxide : A quantitative tracer for fossil fuel CO2?

    NARCIS (Netherlands)

    Gamnitzer, Ulrike; Karstens, Ute; Kromer, Bernd; Neubert, Rolf E. M.; Meijer, Harro A. J.; Schroeder, Hartwig; Levin, Ingeborg

    2006-01-01

    Carbon monoxide (CO), carbon dioxide (CO2), and radiocarbon ((CO2)-C-14) measurements have been made in Heidelberg from 2001 to 2004 in order to determine the regional fossil fuel CO2 component and to investigate the application of CO as a quantitative tracer for fossil fuel CO2 (CO2(foss)). The obs

  16. Hydrogen, carbon monoxide, and methane in the marine environment

    OpenAIRE

    Bullister, John Logan

    1980-01-01

    EXTRACT (SEE PDF FOR FULL ABSTRACT): The horizontal and vertical distribution of three dissolved trace gases, namely molecular hydrogen, carbon monoxide, and methane, was measured in coastal and oceanic areas. Atmospheric concentrations of these gases were measured both at locations influenced by nearby human activity, and in areas far removed from these inputs.

  17. Carbon monoxide poisoning mimicking long-QT induced syncope

    NARCIS (Netherlands)

    I.M. Onvlee-Dekker (Irene); A.C.H. de Vries (Andrica); A.D.J. ten Harkel (Arend)

    2007-01-01

    textabstractCarbon monoxide (CO)poisoning is a rare cause of QT prolongation, and is therefore easily missed. The case of a patient with unexplained syncope and QT prologation on the electrocardiogram that turned out to be related to CO poisoning is reported here. In patients with QT prolongation,

  18. Optimization of Treatment Policy for Acute Carbon Monoxide Poisoning

    Directory of Open Access Journals (Sweden)

    R. N. Akalayev

    2012-01-01

    Full Text Available Objective: to evaluate the efficiency of combination use of hyperbaric oxygenation, succinate-containing solutions, and anti-edematous agents in patients with acute carbon monoxide poisoning. Subjects and methods. The results of treatment were analyzed in 32 patients admitted in 2009—2011 for severe acute carbon monoxide poisoning and a Glasgow coma score of 6—8. The patients were divided into 2 groups: 1 patients whose combination therapy involved hyperbaric oxygenation, Succinasol infusions, and L-lysine-aescinate injections; 2 those who received traditional therapy. All the patients underwent complex clinical, laboratory, and neurophysiologic examinations. Results. Just 24 hours after the combination use of Succinasol and L-lysine-aescinate, Group I patients were observed to have substantially reduced lactate, the content of the latter approached the normal value following 48 hours, which was much below the values in the control group. The similar pattern was observed when endogenous intoxication parameters were examined. During the performed therapy, the level of consciousness and that of intellect according to the MMSE and FAB scales were restored more rapidly in the study group patients than in Group 2. Conclusion. The combination use of hyperbaric oxygenation, the succinate-containing solution Succinasol, and the anti-edematous agent L-lysine-aescinate considerably enhances the efficiency of intensive therapy for acute carbon monoxide poisoning. Key words: carbon monoxide, toxic hypoxic encephalopathy, combination therapy, hyperbaric oxygenation, succinic acid, L-lysine-aescinate.

  19. Ultrasound and photochemical procedures for nanocatalysts preparation: application in photocatalytic biomass valorization.

    Science.gov (United States)

    Colmenares, Juan Carlos

    2013-07-01

    Nano-photocatalysis is becoming increasingly important due to its multiple applications and multidisciplinary aspects. Applications such as water/air purification, solar energy storage, chemicals production and optoelectronics are some of the most promising. In recent years, the development of novel environmental friendly and cost efficient methods for materials preparation that could replace the old ones is on demand. Unconventional and "soft" techniques such as sonication and photochemistry offer huge possibilities for the synthesis of a broad spectrum of nanostructured materials (e.g., nano-photocatalysts). In the present study, I focus on ultrasound and photochemical procedures for the preparation of nanostructured photocatalysts (e.g., supported metals, metal oxides) and their application in food organic wastes valorization.

  20. Light-induced changes in bottled white wine and underlying photochemical mechanisms.

    Science.gov (United States)

    Grant-Preece, Paris; Barril, Celia; Schmidtke, Leigh M; Scollary, Geoffrey R; Clark, Andrew C

    2017-03-04

    Bottled white wine may be exposed to UV-visible light for considerable periods of time before it is consumed. Light exposure may induce an off-flavor known as "sunlight" flavor, bleach the color of the wine, and/or increase browning and deplete sulfur dioxide. The changes that occur in bottled white wine exposed to light depend on the wine composition, the irradiation conditions, and the light exposure time. The light-induced changes in the aroma, volatile composition, color, and concentrations of oxygen and sulfur dioxide in bottled white wine are reviewed. In addition, the photochemical reactions thought to have a role in these changes are described. These include the riboflavin-sensitized oxidation of methionine, resulting in the formation of methanethiol and dimethyl disulfide, and the photodegradation of iron(III) tartrate, which gives rise to glyoxylic acid, an aldehyde known to react with flavan-3-ols to form yellow xanthylium cation pigments.

  1. Chemical degradation of proteins in the solid state with a focus on photochemical reactions.

    Science.gov (United States)

    Mozziconacci, Olivier; Schöneich, Christian

    2015-10-01

    Protein pharmaceuticals comprise an increasing fraction of marketed products but the limited solution stability of proteins requires considerable research effort to prepare stable formulations. An alternative is solid formulation, as proteins in the solid state are thermodynamically less susceptible to degradation. Nevertheless, within the time of storage a large panel of kinetically controlled degradation reactions can occur such as, e.g., hydrolysis reactions, the formation of diketopiperazine, condensation and aggregation reactions. These mechanisms of degradation in protein solids are relatively well covered by the literature. Considerably less is known about oxidative and photochemical reactions of solid proteins. This review will provide an overview over photolytic and non-photolytic degradation reactions, and specially emphasize mechanistic details on how solid structure may affect the interaction of protein solids with light.

  2. Photochemical Charge Separation in Nanocrystal Photocatalyst Films: Insights from Surface Photovoltage Spectroscopy.

    Science.gov (United States)

    Zhao, Jing; Osterloh, Frank E

    2014-03-01

    Photochemical charge generation, separation, and transport at nanocrystal interfaces are central to photoelectrochemical water splitting, a pathway to hydrogen from solar energy. Here, we use surface photovoltage spectroscopy to probe these processes in nanocrystal films of HCa2Nb3O10, a proven photocatalyst. Charge injection from the nanoparticles into the gold support can be observed, as well as oxidation and reduction of methanol and oxygen adsorbates on the nanosheet films. The measured photovoltage depends on the illumination intensity and substrate material, and it varies with illumination time and with film thickness. The proposed model predicts that the photovoltage is limited by the built-in potential of the nanosheet-metal junction, that is, the difference of Fermi energies in the two materials. The ability to measure and understand these light-induced charge separation processes in easy-to-fabricate films will promote the development of nanocrystal applications in photoelectrochemical cells, photovoltaics, and photocatalysts.

  3. Photophysical and photochemical effects in ultrafast laser patterning of CVD graphene

    Science.gov (United States)

    Bobrinetskiy, Ivan; Emelianov, Aleksei; Nasibulin, Albert; Komarov, Ivan; Otero, Nerea; Romero, Pablo M.

    2016-10-01

    The micro-scale patterns in graphene on Si/SiO2 substrate were fabricated using ultrashort 515 nm laser pulses. For both picosecond and femtosecond laser pulses two competitive processes, based on photo-thermal (ablation) and photochemical (oxidation/etching) effects, were observed. The laser-induced etching of graphene starts just below the threshold energy of graphene ablation: 1.7 nJ per 280 fs pulse and 2.7 µJ per 30 ps pulse. Whilst etching is not sensitive to thermal properties of graphene and provides uniform patterns, the ablation, in contrast, is highly affected by defects in the graphene structure like wrinkles and bilayer islands. The mechanisms of ultrafast laser interaction with graphene are discussed.

  4. From small aromatic molecules to functional nanostructured carbon by pulsed laser-induced photochemical stitching

    Directory of Open Access Journals (Sweden)

    R. R. Gokhale

    2012-06-01

    Full Text Available A novel route employing UV laser pulses (KrF Excimer, 248 nm to cleave small aromatic molecules and stitch the generated free radicals into functional nanostructured forms of carbon is introduced. The process differs distinctly from any strategies wherein the aromatic rings are broken in the primary process. It is demonstrated that this pulsed laser-induced photochemical stitching (PLPS process when applied to routine laboratory solvents (or toxic chemical wastes when discarded Chlorobenzene and o-Dichlorobenzene yields Carbon Nanospheres (CNSs comprising of graphene-like sheets assembled in onion-like configurations. This room temperature process implemented under normal laboratory conditions is versatile and clearly applicable to the whole family of haloaromatic compounds without and with additions of precursors or other nanomaterials. We further bring out its applicability for synthesis of metal-oxide based carbon nanocomposites.

  5. Polymeric Framboidal Nanoparticles Loaded with a Carbon Monoxide Donor via Phenylboronic Acid-Catechol Complexation.

    Science.gov (United States)

    van der Vlies, André J; Inubushi, Ryosuke; Uyama, Hiroshi; Hasegawa, Urara

    2016-06-15

    Carbon monoxide (CO) is an essential gaseous signaling molecule in the human body. Toward the controlled delivery of CO to the target tissues or cells, nanomaterial-based CO donors have attracted growing attention. Here, we present CO-releasing polymeric nanoparticles (CONPs) prepared by simple mixing of phenylboronic acid-containing framboidal nanoparticles with the catechol-bearing CO-donor Ru(CO)3Cl(L-DOPA) via phenylboronic acid-catechol complexation. The CONPs release CO in response to cysteine and suppress the production of the pro-inflammatory mediators interleukin 6 (IL-6) and nitric oxide (NO) in lipopolysaccharide (LPS)-stimulated murine macrophages. This CONP platform may show promise in therapeutic applications of CO.

  6. Efficient preparation of carbamates by Rh-catalysed oxidative carbonylation: unveiling the role of the oxidant.

    Science.gov (United States)

    Iturmendi, Amaia; Iglesias, Manuel; Munárriz, Julen; Polo, Victor; Pérez-Torrente, Jesús J; Oro, Luis A

    2016-12-22

    The synthesis of a wide variety of carbamates from amines, alcohols and carbon monoxide has been achieved by means of a Rh-catalysed oxidative carbonylation reaction that uses Oxone as a stoichiometric oxidant. In-depth studies on the reaction mechanism shed light on the intimate role of Oxone in the catalytic cycle.

  7. Mechanistic studies of carbon monoxide reduction

    Energy Technology Data Exchange (ETDEWEB)

    Geoffroy, G.L.

    1990-06-12

    The progress made during the current grant period (1 January 1988--1 April 1990) in three different areas of research is summarized. The research areas are: (1) oxidatively-induced double carbonylation reactions to form {alpha}-ketoacyl complexes and studies of the reactivity of the resulting compounds, (2) mechanistic studies of the carbonylation of nitroaromatics to form isocyanates, carbamates, and ureas, and (3) studies of the formation and reactivity of unusual metallacycles and alkylidene ligands supported on binuclear iron carbonyl fragments. 18 refs., 5 figs., 1 tab.

  8. In Situ Photochemical Activation of Sulfate for Enhanced Degradation of Organic Pollutants in Water.

    Science.gov (United States)

    Liu, Guoshuai; You, Shijie; Tan, Yang; Ren, Nanqi

    2017-02-21

    The advanced oxidation process (AOP) based on SO4(•-) radicals has been receiving growing attention in water and wastewater treatment. Producing SO4(•-) radicals by activation of peroxymonosulfate or persulfate faces the challenges of high operational cost and potential secondary pollution. In this study, we report the in situ photochemical activation of sulfate (i-PCAS) to produce SO4(•-) radicals with bismuth phosphate (BPO) serving as photocatalyst. The prepared BPO rod-like material could achieve remarkably enhanced degradation of 2,4-dichlorophenol (2,4-DCP) in the presence of sulfate, indicated by the first-order kinetic constant (k = 0.0402 min(-1)) being approximately 2.1 times that in the absence (k = 0.019 min(-1)) at pH-neutral condition. This presented a marked contrast with commercial TiO2 (P25), the performance of which was always inhibited by sulfate. The impact of radical scavenger and electrolyte, combined with electron spin resonance (ESR) measurement, verified the formation of •OH and SO4(•-) radicals during i-PCAS process. According to theoretical calculations, BPO has a sufficiently high valence band potential making it thermodynamically favorable for sulfate oxidation, and weaker interaction with SO4(•-) radicals resulting in higher reactivity toward target organic pollutant. The concept of i-PCAS appears to be attractive for creating new photochemical systems where in situ production of SO4(•-) radicals can be realized by using sulfate originally existing in aqueous environment. This eliminates the need for extrinsic chemicals and pH adjustment, which makes water treatment much easier, more economical, and more sustainable.

  9. Ozone-driven photochemical formation of carboxylic acid groups from alkane groups

    Directory of Open Access Journals (Sweden)

    S. Liu

    2011-03-01

    Full Text Available Carboxylic acids are ubiquitous in atmospheric particles, and they play an important role in the physical and chemical properties of aerosol particles. During measurements in coastal California in the summer of 2009, carboxylic acid functional groups were highly associated with trajectories from an industrial region with high organic mass (OM, likely from fossil fuel combustion emissions. The concentration of carboxylic acid groups peaked during daytime, suggesting a photochemical secondary formation mechanism. This daytime increase in concentration was tightly correlated with O3 mixing ratio, indicating O3 was the likely driver in acid formation. Based on the diurnal cycles of carboxylic acid and alkane groups, the covariation of carboxylic acid groups with O3, and the composition of the Combustion factor resulted from the factor analyses, gas-phase alkane oxidation by OH radicals to form dihyfrofuran followed by further oxidation of dihydrofuran by O3 is the likely acid formation mechanism. Using the multi-day average of the daytime increase of carboxylic acid group concentrations and m/z 44-based Aged Combustion factor, we estimated the lower-bound contributions of secondary organic aerosol (SOA formed in 12-h daytime of processing in a single day to be 30% of the carboxylic acid groups and 25–45% of the Combustion factor concentration. These unique ambient observations of photochemically-driven acid formation suggest that gas-phase alkanes might be important sources of SOA formation in this coastal region.

  10. Chemical composition and photochemical reactivity of exhaust from aircraft turbine engines

    Directory of Open Access Journals (Sweden)

    T. F. Lyon

    Full Text Available Assessment of the environmental impact of aircraft emissions is required by planners and policy makers. Seveal areas of concern are: 1. exposure of airport workers and urban residents to toxic chemicals emitted when the engines operate at low power (idle and taxi on the ground; 2. contributions to urban photochemical air pollution of aircraft volatile organic and nitrogen oxides emissions from operations around airports; and 3. emissions of nitrogen oxides and particles during high-altitude operation. The environmental impact of chemicals emitted from jet aircraft turbine engines has not been firmly established due to lack of data regarding emission rates and identities of the compounds emitted. This paper describes an experimental study of two different aircraft turbine engines designed to determine detailed organic emissions, as well as emissions of inorganic gases. Emissions were measured at several engine power settings. Measurements were made of detailed organic composition from C1 through C17, CO, CO2, NO, NOx, and polycyclic aromatic hydrocarbons. Measurements were made using a multi-port sampling pro be positioned directly behind the engine in the exhaust exit plane. The emission measurements have been used to determine the organic distribution by carbon number and the distribution by compound class at each engine power level. The sum of the organic species was compared with an independent measurement of total organic carbon to assess the carbon mass balance. A portion of the exhaust was captured and irradiated in outdoor smog chambers to assess the photochemical reactivity of the emissions with respect to ozone formation. The reactivity of emissions from the two engines was apportioned by chemical compound class.

  11. Light-induced ruthenium-catalyzed nitrene transfer reactions: a photochemical approach towards N-acyl sulfimides and sulfoximines.

    Science.gov (United States)

    Bizet, Vincent; Buglioni, Laura; Bolm, Carsten

    2014-05-26

    1,4,2-Dioxazol-5-ones are five-membered heterocycles known to decarboxylate under thermal or photochemical conditions, thus yielding N-acyl nitrenes. Described herein is a light-induced ruthenium-catalyzed N-acyl nitrene transfer to sulfides and sulfoxides by decarboxylation of 1,4,2-dioxazol-5-ones at room temperature, thus providing direct access to N-acyl sulfimides and sulfoximines under mild reaction conditions. In addition, a one-pot sulfur imidation/oxidation sequence catalyzed by a single ruthenium complex is reported. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  12. Shock tube measurements of growth constants in the branched-chain ethane-carbon monoxide-oxygen system

    Science.gov (United States)

    Brokaw, R. S.; Brabbs, T. A.; Snyder, C. A.

    1985-01-01

    Exponential free radical growth constants have been measured for ethane carbon monoxide oxygen mixtures by monitoring the growth of oxygen atom concentration as manifested by CO flame band emission. Data were obtained over the temperature range of 1200 to 1700 K. The data were analyzed using an ethane oxidation mechanism involving seven elementary reaction steps. Calculated growth constants were close to experimental values at lower temperatures, up to about 1400 K, but at higher temperatures computed growth constants were considerably smaller than experiment. In attempts to explain these results additional branching reactions were added to the mechanism. However, these additional reactions did not appreciably change calculated growth constants.

  13. CO Adsorption and Oxidation at the Catalyst-Water Interface: An Investigation by Attenuated Total Reflection Infrared Spectroscopy.

    NARCIS (Netherlands)

    Ebbesen, S.D.; Mojet, Barbara; Lefferts, Leonardus

    2006-01-01

    Adsorption of carbon monoxide and oxidation of preadsorbed carbon monoxide from gas and aqueous phases were studied on a platinum catalyst deposited on a ZnSe internal reflection element (IRE) using attenuated total reflection infrared (ATR-IR) spectroscopy. The results of this study convincingly

  14. Photochemical transformation of aircraft exhausts at their transition from the plume to the large scale dispersion in the Northern temperature belt

    Energy Technology Data Exchange (ETDEWEB)

    Karol, I.L.; Kiselev, A.A. [Main Geophysical Observatory, St.Petersburg (Russian Federation)

    1997-12-31

    The 2-D diurnally varying photochemical model of the Northern temperate zonal tropospheric belt with fixed (off line) temperature and air transport is used for the description of the formation of aircraft exhaust concentration distribution in the North Atlantic commercial flight corridor, based on actual flights in summer and winter. A strong diurnal and seasonal variation of emitted NO{sub x} oxidation rate is revealed and evaluated. (author) 11 refs.

  15. Composition/bandgap selective dry photochemical etching of semiconductor materials

    Energy Technology Data Exchange (ETDEWEB)

    Ashby, C.I.H.; Dishman, J.L.

    1985-10-11

    Disclosed is a method of selectively photochemically dry etching a first semiconductor material of a given composition and direct bandgap Eg/sub 1/ in the presence of a second semiconductor material of a different composition and direct bandgap Eg/sub 2/, wherein Eg/sub 2/ > Eg/sub 1/, said second semiconductor material substantially not being etched during said method. The method comprises subjecting both materials to the same photon flux and to the same gaseous etchant under conditions where said etchant would be ineffective for chemical etching of either material were the photons not present, said photons being of an energy greater than Eg/sub 1/ but less than Eg/sub 2/, whereby said first semiconductor material is photochemically etched and said second material is substantially not etched.

  16. Composition/bandgap selective dry photochemical etching of semiconductor materials

    Energy Technology Data Exchange (ETDEWEB)

    Ashby, Carol I. H. (Edgewood, NM); Dishman, James L. (Albuquerque, NM)

    1987-01-01

    A method of selectively photochemically dry etching a first semiconductor material of a given composition and direct bandgap Eg.sub.1 in the presence of a second semiconductor material of a different composition and direct bandgap Eg.sub.2, wherein Eg.sub.2 >Eg.sub.1, said second semiconductor material substantially not being etched during said method, comprises subjecting both materials to the same photon flux and to the same gaseous etchant under conditions where said etchant would be ineffective for chemical etching of either material were the photons not present, said photons being of an energy greater than Eg.sub.1 but less than Eg.sub.2, whereby said first semiconductor material is photochemically etched and said second material is substantially not etched.

  17. Composition/bandgap selective dry photochemical etching of semiconductor materials

    Energy Technology Data Exchange (ETDEWEB)

    Ashby, C.I.H.; Dishman, J.L.

    1987-03-10

    A method is described of selectively photochemically dry etching a first semiconductor material of a given composition and direct bandgap E/sub g1/ in the presence of a second semiconductor material of a different composition and direct bandgap E/sub g2/, wherein E/sub g2/>E/sub g1/. The second semiconductor material is not substantially etched during the method, comprising subjecting both materials to the same photon flux and to the same gaseous etchant under conditions where the etchant would be ineffective for chemical etching of either material where the photons are not present, the photons being of an energy greater than E/sub g1/ but less than E/sub g2/, whereby the first semiconductor material is photochemically etched and the second material is substantially not etched.

  18. Visible light photocatalysis as a greener approach to photochemical synthesis.

    Science.gov (United States)

    Yoon, Tehshik P; Ischay, Michael A; Du, Juana

    2010-07-01

    Light can be considered an ideal reagent for environmentally friendly, 'green' chemical synthesis; unlike many conventional reagents, light is non-toxic, generates no waste, and can be obtained from renewable sources. Nevertheless, the need for high-energy ultraviolet radiation in most organic photochemical processes has limited both the practicality and environmental benefits of photochemical synthesis on industrially relevant scales. This perspective describes recent approaches to the use of metal polypyridyl photocatalysts in synthetic organic transformations. Given the remarkable photophysical properties of these complexes, these new transformations, which use Ru(bpy)(3)(2+) and related photocatalysts, can be conducted using almost any source of visible light, including both store-bought fluorescent light bulbs and ambient sunlight. Transition metal photocatalysis thus represents a promising strategy towards the development of practical, scalable industrial processes with great environmental benefits.

  19. Spectroscopic studies on the photochemical decarboxylation mechanisms of synthetic pyrethroids.

    Science.gov (United States)

    Suzuki, Yusuke; Ishizaka, Shoji; Kitamura, Noboru

    2012-12-01

    A novel radical trapping technique combined with a fluorescence spectroscopic analysis has been employed to investigate the radical intermediates produced by photodecarboxylation of four synthetic pyrethroids: fenvalerate (SMD), fenpropathrin (DTL), cyphenothrin (GKL), and cypermethrin (AGT). Under photoirradiation at >290 nm, all pyrethroids underwent direct photolysis via homolytic cleavage of the carbon-oxygen bonds in the ester groups. The consumed amount of a nitroxide free radical, as a trapping agent for the intermediate radical of a pyrethroid, was determined by ESR, which was the measure of the reaction yield of a photochemically generated α-cyano-3-phenoxybenzyl radical common to all pyrethroids. The reactivities of the pyrethroids studied was in the sequence of SMD > DTL > GKL > AGT. Furthermore, nanosecond transient absorption spectroscopy demonstrated that geminate recombination of the radical pair within a solvent cage is the main deactivation route of the photochemically generated α-cyano-3-phenoxybenzyl radical common for all pyrethroids studied.

  20. Photochemical manipulation of colloidal structures in liquid-crystal colloids

    Science.gov (United States)

    Yamamoto, T.; Tabe, Y.; Yokoyama, H.

    2007-05-01

    We investigated photochemical manipulation of physical properties and colloidal structures in liquid-crystal (LC) colloids containing azobenzene compounds. In a LC suspension where polymeric particles were dispersed in a host LC, we achieved photochemical control of light-scattering properties of the suspension. In a nematic phase, when the suspension was sandwiched with two glass plates, the film became opaque. This would be attributable to an appearance of both multidomain structures of LC alignment and mismatches of refractive indices between the materials. The opaque state turned into a transparent one when a nematic-to-isotropic phase transition was induced by the trans-to-cis photoisomerization of the azo-dye. This will result from a disappearance of both the multidomain structures and the refractive-index mismatches in the isotropic phase. The transparent film went back into the initial opaque film when the nematic phase was obtained by the cis-to-trans photoisomerization. In a LC emulsion in which glycerol or water droplets were dispersed in liquid crystals, we examined photochemical change of defect structures and inter-droplet distances by the photochemical manner. At the initial state, Saturn ring and hedgehog defects were formed around the droplets. For the glycerol droplets, we observed structural transformations between Saturn ring and boojums on irradiation with ultra-violet and visible light. For the water droplets, the inter-droplet distances varied by changing defect size on the irradiation. These phenomena would result from modulation of anchoring conditions of the droplets by the photoisomerization of the azo-dyes.

  1. The structural basis of non-photochemical quenching is revealed?

    Science.gov (United States)

    Cogdell, Richard J

    2006-02-01

    Light-harvesting complex II (LHCII, the major plant light-harvesting pigment-protein complex, efficiently harvests light-energy. However, if the incident light intensity is too high and photosynthesis becomes saturated, LHCII can switch into a quenching state that prevents photodamage. This important process is called non-photochemical quenching, or NPQ, and represents feedback control. Andrew Pascal et al. have recently proposed a detailed model of NPQ based upon the crystal structure of LHCII from spinach.

  2. Enhanced transfection of brain tumor suppressor genes by photochemical internalization

    Science.gov (United States)

    Chou, Chih H.; Sun, Chung-Ho; Zhou, Yi-Hong; Madsen, Steen J.; Hirschberg, Henry

    2011-03-01

    One of many limitations for cancer gene therapy is the inability of the therapeutic gene to transfect a sufficient number of tumor cells. Photochemical internalization (PCI) is a photodynamic therapy-based approach for improving the delivery of macromolecules and genes into the cell cytosol. The utility of PCI for the delivery of a tumor suppressor gene (PAX-6) was investigated in monolayers and spheroids consisting of F98 rat glioma cells.

  3. Digit and letter alexia in carbon monoxide poisoning

    Institute of Scientific and Technical Information of China (English)

    Qingyu Shen; Xiaoming Rong; Rui Pan; Ying Peng; Wei Peng; Yamei Tang

    2012-01-01

    This study examined a 24-year-old patient with delayed encephalopathy, who was admitted to hospital with complaints of headache and visual impairment 1 week after acute carbon monoxide poisoning. The results of a visual field assessment, electroencephalography and head magnetic resonance imaging indicated damage to the cerebral cortex. After a 2-week treatment period, the patient had recovered from the visual impairment, but exhibited digit- and letter-reading difficulty. The Chinese aphasia battery and the number and letter battery supplement were conducted. The results revealed that the patient exhibited digit and letter alexia, while the ability to read Chinese characters was preserved. In contrast, the patient exhibited a deficit in Chinese character writing, while number and letter writing remained intact. Following treatment, reading and writing ability was improved and electroencephalographic abnormalities were ameliorated. Overall, our experimental findings demonstrated that delayed encephalopathy following acute carbon monoxide poisoning was characterized by digit and letter alexia.

  4. Effect of carbon monoxide on plants. [Mimosa pudica

    Energy Technology Data Exchange (ETDEWEB)

    Zimmerman, P.W.; Crocker, W.; Hitchcock, A.E.

    1933-01-01

    Of 108 species of plants treated with one per cent carbon monoxide, 45 showed epinastic growth of leaves. Several species showed hyponasty which caused upward curling of leaves. Other effects included: retarded stem elongation; abnormally small new leaves; abnormal yellowing of the leaves, beginning with the oldest; abscission of leaves usually associated with yellowing; and hypertrophied tissues on stems and roots. During recovery an abnormally large number of side shoots arose from latent buds of many species. Motion pictures of Mimosa pudica showed a loss of correlation, normal equilibrium position to gravity, and sensitiveness to contact or heat stimuli; however, the leaves moved about more rapidly than those of controls. Since carbon monoxide causes growth rigor and loss of sensitiveness to external stimuli, it is here considered as an anesthetic.

  5. [Heme oxygenase and carbon monoxide in the physiology and pathology of the cardiovascular system].

    Science.gov (United States)

    Bełtowski, Jerzy; Jamroz, Anna; Borkowska, Ewelina

    2004-03-03

    Heme oxygenase (HO) degrades heme to carbon monoxide (CO), ferrous ions, and the bile pigment biliverdin, which is subsequently reduced to the other important bile pigment, bilirubin, by biliverdin reductase. Fe2+ liberated from the heme molecule upregulates ferritin production, and bile pigments are potent endogenous antioxidants. The HO enzyme exists in three isophorms: HO-1 is expressed at low levels under physiological conditions, but is induced by numerous factors, including oxidative stress, inflammation, nitric oxide, an elevated level of substrate, and hypoxia. HO-2 is a constitutive enzyme involved in the baseline production of CO in the cardiovascular and nervous systems, whereas HO-3 is also ubiquitously expressed, but possesses low catalytic activity. Like nitric oxide, CO activates soluble guanylate cyclase and elevates cGMP in target tissues, which dilates blood vessels. It also does this by directly activating potassium channels in vascular smooth muscle cells. In addition, CO inhibits platelet aggregation and proliferation of vascular smooth muscle cells, inhibits apoptosis, and stimulates angiogenesis. Both deficiency, and excess of HO-1 may be involved in the pathogenesis of arterial hypertension. Induction of HO-1 attenuates atherosclerosis and myocardial ischemia-reperfusion injury. Pharmacological and genetic induction of HO-1 as well as the delivery of exogenous CO are promising therapeutic strategies for the treatment of cardiovascular diseases.

  6. [Sudden unilateral sensorineural hearing loss after carbon monoxide intoxication].

    Science.gov (United States)

    Michalska-Piechowiak, Teresa; Miarzyńska, Maria; Perlik-Gattner, Irena

    2004-01-01

    A case of unilateral sensorineural hearing loss of the left ear after carbon monoxide intoxication was presented. The diagnosis was based upon an interview, medical examinations and audiometric investigations. Results of diagnostic evaluations, clinical presentation and treatment were discussed. Hearing improvement was obtained after 6 days of treatment and normal hearing returned after 14 days. Patients who suffer from CO intoxication are at risk of hearing impairment, therefore, there is a need for audiometric follow up in these patients.

  7. Pregnancy Hypertenssion and Preeclampsia in Enviromental Expossure to Carbon Monoxide

    OpenAIRE

    2008-01-01

    Introduction: In this study relationship between carbon monoxide (CO) with pregnancy induced hypertension and preeclampsia in mothers in various levels of CO pollution was evaluated. Methods: The study was carried out in three teaching hospitals and 4500 pregnant women living area divided in one low-level CO polluted and as the second level, three moderate to high polluted areas (central, south and west). The subjects, residence places were within 5 kilometers of the air pollution monitoring ...

  8. Photochemical fate of beta-blockers in NOM enriched waters

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Ling; Xu, Haomin; Cooper, William J. [Urban Water Research Center, Department of Civil and Environmental Engineering, University of California, Irvine, Irvine, CA 92697-2175 (United States); Song, Weihua, E-mail: wsong@fudan.edu.cn [Department of Environmental Science and Engineering, Fudan University, Shanghai 200433 (China)

    2012-06-01

    Beta-blockers, prescribed for the treatment of high blood pressure and for long-term use after a heart attack, have been detected in surface and ground waters. This study examines the photochemical fate of three beta-blockers, atenolol, metoprolol, and nadolol. Hydrolysis accounted for minor losses of these beta-blockers in the pH range 4-10. The rate of direct photolysis at pH 7 in a solar simulator varied from 6.1 to 8.9 h{sup -1} at pH 7. However, the addition of a natural organic matter (NOM) isolate enhanced the photochemical loss of all three compounds. Indirect photochemical fate, generally described by reactions with hydroxyl radical ({center_dot}OH) and singlet oxygen ({sup 1}{Delta}O{sub 2}), and, the direct reaction with the triplet excited state, {sup 3}NOM{sup Low-Asterisk }, also varied but collectively appeared to be the major loss factor. Bimolecular reaction rate constants of the three beta-blockers with {sup 1}{Delta}O{sub 2} and {center_dot}OH were measured and accounted for 0.02-0.04% and 7.2-38.9% of their loss, respectively. These data suggest that the {sup 3}NOM{sup Low-Asterisk} contributed 50.6-85.4%. Experiments with various {sup 3}NOM{sup Low-Asterisk} quenchers supported the hypothesis that it was singly the most important reaction. Atenolol was chosen for more detailed investigation, with the photoproducts identified by LC-MS analysis. The results suggested that electron-transfer could be an important mechanism in photochemical fate of beta-blockers in the presence of NOM. - Highlights: Black-Right-Pointing-Pointer Photochemical degradation of beta-blockers in the simulated natural waters. Black-Right-Pointing-Pointer Reactive Oxygen Species play a minor role in the indirect photodegradation. Black-Right-Pointing-Pointer The loss of beta-blockers results from direct reaction with {sup 3}DOM{sup Low-Asterisk }.

  9. Mobile Carbon Monoxide Monitoring System Based on Arduino-Matlab for Environmental Monitoring Application

    Science.gov (United States)

    Azieda Mohd Bakri, Nur; Junid, Syed Abdul Mutalib Al; Razak, Abdul Hadi Abdul; Idros, Mohd Faizul Md; Karimi Halim, Abdul

    2015-11-01

    Nowadays, the increasing level of carbon monoxide globally has become a serious environmental issue which has been highlighted in most of the country globally. The monitoring of carbon monoxide content is one of the approaches to identify the level of carbon monoxide pollution towards providing the solution for control the level of carbon monoxide produced. Thus, this paper proposed a mobile carbon monoxide monitoring system for measuring the carbon monoxide content based on Arduino-Matlab General User Interface (GUI). The objective of this project is to design, develop and implement the real-time mobile carbon monoxide sensor system and interfacing for measuring the level of carbon monoxide contamination in real environment. Four phases or stages of work have been carried out for the accomplishment of the project, which classified as sensor development, controlling and integrating sensor, data collection and data analysis. As a result, a complete design and developed system has been verified with the handheld industrial standard carbon monoxide sensor for calibrating the sensor sensitivity and measurement in the laboratory. Moreover, the system has been tested in real environments by measuring the level of carbon monoxide in three different lands used location; industrial area; residential area and main road (commercial area). In this real environment test, the industrial area recorded the highest reading with 71.23 ppm and 82.59 ppm for sensor 1 and sensor 2 respectively. As a conclusion, the mobile realtime carbon monoxide system based on the Arduino-Matlab is the best approach to measure the carbon monoxide concentration in different land-used since it does not require a manual data collection and reduce the complexity of the existing carbon monoxide level concentration measurement practise at the same time with a complete data analysis facilities.

  10. Characterization of photochemical pollution at different elevations in mountainous areas in Hong Kong

    Directory of Open Access Journals (Sweden)

    H. Guo

    2013-04-01

    Full Text Available To advance our understanding on the factors that affect photochemical pollution at different elevations in mountainous areas, concurrent systematic field measurements (September to November 2010 were conducted at a mountain site and at an urban site at the foot of the mountain in Hong Kong. The mixing ratios of air pollutants were greater at the foot of the mountain (i.e., Tsuen Wan urban site, TW than near the summit (i.e., Tai Mao Shan mountain site, TMS, expect for ozone. In total, only one O3 episode day was observed at TW, whereas twenty-one (21 O3 episode days were observed at TMS. The discrepancy of O3 at the two sites was attributed to the mixed effects of NO titration, vertical meteorological conditions, regional transport and mesoscale circulations. The lower NO levels at TMS and the smaller differences of "oxidant" Ox (O3 + NO2 between the two sites suggested that variations of O3 at the two sites were partly attributed to different degree of NO titration. In addition, analysis of vertical structure of meteorological variables revealed that the inversion layer at the range of altitudes of 500–1000 m might be another factor that caused the high O3 levels at TMS. Furthermore, analyses of the wind fields, the levels of air pollutants in different air flows, ratios of different trace gases and the correlation between variability and the lifetime of VOCs (volatile organic compounds indicated that high O3 concentrations at TMS were somewhat influenced by regional air masses from the highly polluted Pearl River delta (PRD region. In particular, the diurnal profiles and correlations of gaseous pollutants suggested influence of mesoscale circulations, which is confirmed using the Master Chemical Mechanism moving box model (Mbox and the Weather Research and Forecasting (WRF model. By investigating the correlations of observed O3 and NOx* and the relationships of O3 and its precursors by an observation-based model (OBM, as well as the ratios

  11. Photochemical CVD of Ru on functionalized self-assembled monolayers from organometallic precursors

    Science.gov (United States)

    Johnson, Kelsea R.; Arevalo Rodriguez, Paul; Brewer, Christopher R.; Brannaka, Joseph A.; Shi, Zhiwei; Yang, Jing; Salazar, Bryan; McElwee-White, Lisa; Walker, Amy V.

    2017-02-01

    Chemical vapor deposition (CVD) is an attractive technique for the metallization of organic thin films because it is selective and the thickness of the deposited film can easily be controlled. However, thermal CVD processes often require high temperatures which are generally incompatible with organic films. In this paper, we perform proof-of-concept studies of photochemical CVD to metallize organic thin films. In this method, a precursor undergoes photolytic decomposition to generate thermally labile intermediates prior to adsorption on the sample. Three readily available Ru precursors, CpRu(CO)2Me, (η3-allyl)Ru(CO)3Br, and (COT)Ru(CO)3, were employed to investigate the role of precursor quantum yield, ligand chemistry, and the Ru oxidation state on the deposition. To investigate the role of the substrate chemistry on deposition, carboxylic acid-, hydroxyl-, and methyl-terminated self-assembled monolayers were used. The data indicate that moderate quantum yields for ligand loss (φ ≥ 0.4) are required for ruthenium deposition, and the deposition is wavelength dependent. Second, anionic polyhapto ligands such as cyclopentadienyl and allyl are more difficult to remove than carbonyls, halides, and alkyls. Third, in contrast to the atomic layer deposition, acid-base reactions between the precursor and the substrate are more effective for deposition than nucleophilic reactions. Finally, the data suggest that selective deposition can be achieved on organic thin films by judicious choice of precursor and functional groups present on the substrate. These studies thus provide guidelines for the rational design of new precursors specifically for selective photochemical CVD on organic substrates.

  12. Photochemical grid model implementation of VOC, NOx, and O3 source apportionment

    Directory of Open Access Journals (Sweden)

    R. H. F. Kwok

    2014-09-01

    Full Text Available For the purposes of developing optimal emissions control strategies, efficient approaches are needed to identify the major sources or groups of sources that contribute to elevated ozone (O3 concentrations. Source based apportionment techniques implemented in photochemical grid models track sources through the physical and chemical processes important to the formation and transport of air pollutants. Photochemical model source apportionment has been used to estimate impacts of specific sources, groups of sources (sectors, sources in specific geographic areas, and stratospheric and lateral boundary inflow on O3. The implementation and application of a source apportionment technique for O3 and its precursors, nitrogen oxides (NOx and volatile organic compounds (VOC, for the Community Multiscale Air Quality (CMAQ model are described here. The Integrated Source Apportionment Method (ISAM O3 approach is a hybrid of source apportionment and source sensitivity in that O3 production is attributed to precursor sources based on O3 formation regime (e.g., for a NOx-sensitive regime, O3 is apportioned to participating NOx emissions. This implementation is illustrated by tracking multiple emissions source sectors and lateral boundary inflow. NOx, VOC, and O3 attribution to tracked sectors in the application are consistent with spatial and temporal patterns of precursor emissions. The O3 ISAM implementation is further evaluated through comparisons of apportioned ambient concentrations and deposition amounts with those derived from brute force zero-out scenarios, with correlation coefficients ranging between 0.58 and 0.99 depending on specific combination of target species and tracked precursor emissions. Low correlation coefficients occur for chemical regimes that have strong non-linearity in O3 sensitivity, which demonstrates different functionalities between source apportionment and zero-out approaches, depending on whether sources of interest are either to

  13. Ferrous iron oxidation by anoxygenic phototrophic bacteria

    OpenAIRE

    Widdel, Friedrich; Schnell, Sylvia; Heising, Silke; Ehrenreich, Armin; Assmus, Bernhard; Schink, Bernhard

    1993-01-01

    Natural oxidation of ferrous to ferric iron by bacteria such as Thiobacillus ferrooxidans or Gallionella ferruginea 1, or by chemical oxidation2,3 has previously been thought always to involve molecular oxygen as the electron acceptor. Anoxic photochemical reactions4 6 or a photobiological process involving two photosystems7 9 have also been discussed as mechanisms of ferrous iron oxidation. The knowledge of such processes has implications that bear on our understanding of the origin of Preca...

  14. Heterologous Production of an Energy-Conserving Carbon Monoxide Dehydrogenase Complex in the Hyperthermophile Pyrococcus furiosus

    Science.gov (United States)

    Schut, Gerrit J.; Lipscomb, Gina L.; Nguyen, Diep M. N.; Kelly, Robert M.; Adams, Michael W. W.

    2016-01-01

    Carbon monoxide (CO) is an important intermediate in anaerobic carbon fixation pathways in acetogenesis and methanogenesis. In addition, some anaerobes can utilize CO as an energy source. In the hyperthermophilic archaeon Thermococcus onnurineus, which grows optimally at 80°C, CO oxidation and energy conservation is accomplished by a respiratory complex encoded by a 16-gene cluster containing a CO dehydrogenase, a membrane-bound [NiFe]-hydrogenase and a Na+/H+ antiporter module. This complex oxidizes CO, evolves CO2 and H2, and generates a Na+ motive force that is used to conserve energy by a Na+-dependent ATP synthase. Herein we used a bacterial artificial chromosome to insert the 13.2 kb gene cluster encoding the CO-oxidizing respiratory complex of T. onnurineus into the genome of the heterotrophic archaeon, Pyrococcus furiosus, which grows optimally at 100°C. P. furiosus is normally unable to utilize CO, however, the recombinant strain readily oxidized CO and generated H2 at 80°C. Moreover, CO also served as an energy source and allowed the P. furiosus strain to grow with a limiting concentration of sugar or with peptides as the carbon source. Moreover, CO oxidation by P. furiosus was also coupled to the re-utilization, presumably for biosynthesis, of acetate generated by fermentation. The functional transfer of CO utilization between Thermococcus and Pyrococcus species demonstrated herein is representative of the horizontal gene transfer of an environmentally relevant metabolic capability. The transfer of CO utilizing, hydrogen-producing genetic modules also has applications for biohydrogen production and a CO-based industrial platform for various thermophilic organisms. PMID:26858706

  15. On the in vivo photochemical rate parameters for PDT reactive oxygen species modeling

    Science.gov (United States)

    Kim, Michele M.; Ghogare, Ashwini A.; Greer, Alexander; Zhu, Timothy C.

    2017-03-01

    Photosensitizer photochemical parameters are crucial data in accurate dosimetry for photodynamic therapy (PDT) based on photochemical modeling. Progress has been made in the last few decades in determining the photochemical properties of commonly used photosensitizers (PS), but mostly in solution or in vitro. Recent developments allow for the estimation of some of these photochemical parameters in vivo. This review will cover the currently available in vivo photochemical properties of photosensitizers as well as the techniques for measuring those parameters. Furthermore, photochemical parameters that are independent of environmental factors or are universal for different photosensitizers will be examined. Most photosensitizers discussed in this review are of the type II (singlet oxygen) photooxidation category, although type I photosensitizers that involve other reactive oxygen species (ROS) will be discussed as well. The compilation of these parameters will be essential for ROS modeling of PDT.

  16. Carbon Monoxide Distribution over Peninsular Malaysia from the Atmospheric Infrared Sounder (AIRS)

    Science.gov (United States)

    Rajab, Jaso M.; MatJafri, M. Z.; Lim, H. S.; Abdullah, K.

    2009-07-01

    The Atmospheric Infrared Sounder (AIRS) onboard NASA's Aqua satellite. It daily coverage of ˜70% of the planet represents a significant evolutionary advance in satellite traces gas remote sensing. AIRS, the part of a large international investment to upgrade the operational meteorological satellite systems, is first of the new generation of meteorological advanced sounders for operational and research use, Providing New Insights into Weather and Climate for the 21st Century. Carbon monoxide (CO) is a ubiquitous, an indoor and outdoor air pollutant, is not a significant greenhouse gas as it absorbs little infrared radiation from the Earth. However, it does have an influence on oxidization in the atmosphere through interaction with hydroxyl radicals (OH), which also react with methane, halocarbons and tropospheric ozone. It produced by the incomplete combustion of fossil fuels and biomass burning, and that it has a role as a smog. The aim of this investigation is to study the (CO) carbon monoxide distribution over Peninsular Malaysia. The land use map of the Peninsular Malaysia was conducted by using CO total column amount, obtained from AIRS data, the map & data was processed and analyzed by using Photoshop & SigmaPlot 11.0 programs and compared for timing of various (day time) (28 August 2005 & 29 August 2007) for both direct comparison and the comparison using the same a priori profile, the CO concentrations in 28/8/2005 higher. The CO maps were generated using Kriging Interpolation technique. This interpolation technique produced high correlation coefficient, R2 and low root mean square error, RMS for CO. This study provided useful information for influence change of CO concentration on varies temperature.

  17. Central Diabetes Insipidus and Hyperglycemic Hyperosmolar State Following Accidental Carbon Monoxide Poisoning.

    Science.gov (United States)

    Ul Abideen, Zain; Mahmud, Syed Nayer; Rasheed, Amna; Farooq Qasim, Yusaf; Ali, Furqan

    2017-06-03

    Carbon monoxide poisoning is common and carries significant morbidity and mortality. The nervous system, particularly the brain, is frequently affected by it, owing to its high metabolic activity and oxygen requirements. Carbon monoxide damages the nervous system by both hypoxic and inflammatory mechanisms. Central diabetes insipidus is an extremely rare complication of carbon monoxide poisoning. Herein, we report the case of a young lady, who developed this complication and severe hypernatremia after accidental carbon monoxide poisoning. She also developed a hyperglycemic hyperosmolar state during the treatment for hypernatremia. To the best of our knowledge, both these entities have not been reported together in association with carbon monoxide poisoning. The purpose of this article is to emphasize the anticipation and early recognition of central diabetes insipidus in carbon monoxide poisoning. This can prevent severe hypernatremia and complications associated with its presence and treatment.

  18. Closed system Fischer-Tropsch synthesis over meteoritic iron, iron ore and nickel-iron alloy. [deuterium-carbon monoxide reaction catalysis

    Science.gov (United States)

    Nooner, D. W.; Gibert, J. M.; Gelpi, E.; Oro, J.

    1976-01-01

    Experiments were performed in which meteoritic iron, iron ore and nickel-iron alloy were used to catalyze (in Fischer-Tropsch synthesis) the reaction of deuterium and carbon monoxide in a closed vessel. Normal alkanes and alkenes and their monomethyl substituted isomers and aromatic hydrocarbons were synthesized. Iron oxide and oxidized-reduced Canyon Diablo used as Fischer-Tropsch catalysts were found to produce aromatic hydrocarbons in distributions having many of the features of those observed in carbonaceous chondrites, but only at temperatures and reaction times well above 300 C and 6-8 h.

  19. Photochemical Cyclopolymerization of Polyimides in Ultraviolet Ridgidizing Composites for Use in Inflatable Structures Project

    Data.gov (United States)

    National Aeronautics and Space Administration — This innovation uses photochemical cyclopolymerization of polyimides to manufacture ultraviolet rigidizable composites for use in RIS (ridgidizing inflatable)...

  20. Photochemical Reactivity of Dissolved Organic Matter in Boreal Lakes

    Science.gov (United States)

    Gu, Y.; Vuorio, K.; Tiirola, M.; Perämäki, S.; Vahatalo, A.

    2016-12-01

    Boreal lakes are rich in dissolved organic matter (DOM) that terrestrially derived from forest soil and wetland, yet little is known about potential for photochemical transformation of aquatic DOM in boreal lakes. Transformation of chromophoric dissolved organic matter (CDOM) can decrease water color and enhance microbial mineralization, affecting primary production and respiration, which both affect the CO2 balance of the lakes. We used laboratory solar radiation exposure experiments with lake water samples collected from 54 lakes located in Finland and Sweden, representing different catchment composition and watershed location to assess photochemical reactivity of DOM. The pH of water samples ranged from 5.4 to 8.3, and the concentrations of dissolved iron (Fe) were between sunlight, and photomineralization of dissolved organic carbon (DOC) to dissolved inorganic carbon (DIC) was measured for determination of spectral apparent quantum yields (AQY). During irradiation, photobleaching decreased the absorption coefficients of CDOM at 330 nm between 4.9 and 79 m-1 by 0.5 to 11 m-1. Irradiation generated DIC from 2.8 to 79 μmol C L-1. The AQY at 330 nm ranged between 31 and 273 ×10-6 mol C mol photons-1 h-1, which was correlated positively with concentration of dissolved Fe, and negatively with pH. Further statistical analyze indicated that the interaction between pH and Fe may explain much of the photochemical reactivity of DOM in the examined lakes, and land cover concerns main catchment areas also can have impact on the photoreaction process. This study may suggest how environmental conditions regulate DOM photomineralization in boreal lakes.