WorldWideScience

Sample records for atmospheric oxidation by-products

  1. Study of Atmospheric Nitric Oxide

    Science.gov (United States)

    Dalgarno, A.

    1998-01-01

    We investigated the contribution of energetic nitrogen atoms to the production of nitric oxide in the thermosphere and their influence on the infrared emission spectrum. The nitric oxide molecules are important contributors to the cooling of the atmosphere. We first pointed out that in determining the energy distribution of the nitrogen atoms, it is important to take into account the thermal motion of the atmospheric gases. It had been ignored in all earlier studies. The source spectra are broadened considerably by the center of mass motion of the reactants. We worked out the consequences for the production of nitric oxide at night, using as sources of energetic N atoms, NO(+) + e yield N + O, N(D-2) + O yield N + O. The high energy tail is enhanced by orders of magnitude. We had earlier suggested (Sharma et al. 1993) that the reaction of energetic nitrogen atoms with O2 was responsible for the rotationally enhanced NO identified in the infrared spectrum. Our calculations provided quantitative confirmation of the suggestion. We proceeded to explore the validity of another approximation used in earlier analyses, the hard sphere approximation for the energy loss in elastic collisions. We carried out precise quantum mechanical calculations of the elastic 2 differential scattering of nitrogen atoms in collisions with oxygen atoms and showed that although the hard sphere approximation was nowhere of high precision, reasonable results could be obtained with an effective cross section of 6 x 10(exp 15)sq cm. We also initiated a program to include inelastic energy loss processes in the determination of the energy distribution function. We began a calculation of the rotation and vibrational excitation cross sections of molecular nitrogen and nitrogen atoms and developed a method for including inelastic energy loss as a function of scattering angle in the Boltzmann equation. A procedure for obtaining the solution of the Boltzman equation was worked out.

  2. Atmospheric oxidation of selected hydrocarbons

    Energy Technology Data Exchange (ETDEWEB)

    Benter, T.; Olariu, R.I.

    2002-02-01

    This work presents investigations on the gas-phase chemistry of phenol and the cresol isomers performed in a 1080 l quartz glass reactor in Wuppertal and in a large-volume outdoor photoreactor EUPHORE in Valencia, Spain. The studies aimed at clarifying the oxidation mechanisms of the reactions of these compounds with OH and NO{sub 3} radicals. Product investigations on the oxidation of phenol and the cresol isomers initiated by OH radicals were performed in the 1080 l quartz glass reactor with analyses by in situ FT-IR absorption spectroscopy. The primary focus of the investigations was on the determination of product yields. This work represents the first determination and quantification of 1,2-dihydroxybenzenes in the OH oxidation of phenolic compounds. Possible reaction pathways leading to the observed products have been elucidated. (orig.)

  3. Atmospheric oxidation of selected alcohols and esters

    Energy Technology Data Exchange (ETDEWEB)

    Becker, K.H.; Cavalli, F.

    2001-03-01

    The decision whether it is appropriate and beneficial for the environment to deploy specific oxygenated organic compounds as replacements for traditional solvent types requires a quantitative assessment of their potential atmospheric impacts including tropospheric ozone and other photooxidant formation. This involves developing chemical mechanisms for the gasphase atmospheric oxidation of the compounds which can be reliably used in models to predict their atmospheric reactivity under a variety of environmental conditions. Until this study, there was very little information available concerning the atmospheric fate of alcohols and esters. The objectives of this study were to measure the atmospheric reaction rates and to define atmospheric reaction mechanisms for the following selected oxygenated volatile organic compounds: the alcohols, 1-butanol and 1-pentanol, and the esters, methyl propionate and dimethyl succinate. The study has successfully addressed these objectives. (orig.)

  4. Greenhouse effect due to atmospheric nitrous oxide

    Science.gov (United States)

    Yung, Y. L.; Wang, W. C.; Lacis, A. A.

    1976-01-01

    The greenhouse effect due to nitrous oxide in the present atmosphere is about 0.8 K. Increase in atmospheric N2O due to perturbation of the nitrogen cycle by man may lead to an increase in surface temperature as large as 0.5 K by 2025, or 1.0 K by 2100. Other climatic effects of N2O are briefly discussed.

  5. Primary atmospheric oxidation mechanism for toluene.

    Science.gov (United States)

    Baltaretu, Cristian O; Lichtman, Eben I; Hadler, Amelia B; Elrod, Matthew J

    2009-01-01

    The products of the primary OH-initiated oxidation of toluene were investigated using the turbulent flow chemical ionization mass spectrometry technique at temperatures ranging from 228 to 298 K. A major dienedial-producing pathway was detected for the first time for toluene oxidation, and glyoxal and methylglyoxal were found to be minor primary oxidation products. The results suggest that secondary oxidation processes involving dienedial and epoxide primary products are likely responsible for previous observations of glyoxal and methylglyoxal products from toluene oxidation. Because the dienedial-producing pathway is a null cycle for tropospheric ozone production and glyoxal and methylglyoxal are important secondary organic aerosol precursors, these new findings have important implications for the modeling of toluene oxidation in the atmosphere.

  6. Primary atmospheric oxidation mechanism for toluene.

    Science.gov (United States)

    Baltaretu, Cristian O; Lichtman, Eben I; Hadler, Amelia B; Elrod, Matthew J

    2009-01-01

    The products of the primary OH-initiated oxidation of toluene were investigated using the turbulent flow chemical ionization mass spectrometry technique at temperatures ranging from 228 to 298 K. A major dienedial-producing pathway was detected for the first time for toluene oxidation, and glyoxal and methylglyoxal were found to be minor primary oxidation products. The results suggest that secondary oxidation processes involving dienedial and epoxide primary products are likely responsible for previous observations of glyoxal and methylglyoxal products from toluene oxidation. Because the dienedial-producing pathway is a null cycle for tropospheric ozone production and glyoxal and methylglyoxal are important secondary organic aerosol precursors, these new findings have important implications for the modeling of toluene oxidation in the atmosphere. PMID:19118482

  7. Oxidation and Assimilation of Atmospheric Methane by Soil Methane Oxidizers

    OpenAIRE

    Roslev, P.; Iversen, N.; Henriksen, K.

    1997-01-01

    The metabolism of atmospheric methane in a forest soil was studied by radiotracer techniques. Maximum (sup14)CH(inf4) oxidation (163.5 pmol of C cm(sup-3) h(sup-1)) and (sup14)C assimilation (50.3 pmol of C cm(sup-3) h(sup-1)) occurred at the A(inf2) horizon located 15 to 18 cm below the soil surface. At this depth, 31 to 43% of the atmospheric methane oxidized was assimilated into microbial biomass; the remaining methane was recovered as (sup14)CO(inf2). Methane-derived carbon was incorporat...

  8. A new method for quantitatively characterizing atmospheric oxidation capacity

    Institute of Scientific and Technical Information of China (English)

    CHENG YanLi; WANG XueSong; LIU ZhaoRong; BAI YuHua; LI JinLong

    2008-01-01

    Based on atmospheric chemical kinetics, the rate constant of overall pseudo-first order oxidation re-moval of gaseous pollutants (Kpor.T) is proposed to characterize the atmospheric oxidation capacity in troposphere. Being a quantitative parameter, Kpor,T can be used to address the issues related to at-mospheric oxidation capacity. By applying this method, the regional oxidation capacity of the atmos-phere in Pearl River Delta (PRD) is numerically simulated based on CBM-Ⅳ chemical mechanism. Re-sults show the significant spatio-temporal variation of the atmospheric oxidation capacity in PRD. It is found that OH initiated oxidations, heterogeneous oxidation of SO2, and photolysis of aldehydes are the three most important oxidation processes influencing the atmospheric oxidation capacity in PRD.

  9. A new method for quantitatively characterizing atmospheric oxidation capacity

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    Based on atmospheric chemical kinetics, the rate constant of overall pseudo-first order oxidation re-moval of gaseous pollutants (Kpor,T) is proposed to characterize the atmospheric oxidation capacity in troposphere. Being a quantitative parameter, Kpor,T can be used to address the issues related to at-mospheric oxidation capacity. By applying this method, the regional oxidation capacity of the atmos-phere in Pearl River Delta (PRD) is numerically simulated based on CBM-IV chemical mechanism. Re-sults show the significant spatio-temporal variation of the atmospheric oxidation capacity in PRD. It is found that OH initiated oxidations, heterogeneous oxidation of SO2, and photolysis of aldehydes are the three most important oxidation processes influencing the atmospheric oxidation capacity in PRD.

  10. Removing of Disinfection By-Product Precursors from Surface Water by Using Magnetic Graphene Oxide.

    Directory of Open Access Journals (Sweden)

    Zhongmou Liu

    Full Text Available The magnetic graphene oxide (MGO was successfully synthesised by the in situ chemical co-precipitation method with Fe3+, Fe2+ and graphene oxide (GO in laboratory and, was used as an adsorbent for disinfection by-product (DBP precursors removing from four natural surface water samples. The results indicate that various DBPs formation significantly decreased by 7-19% to 78-98% for the four samples after MGO treatment and, the treatment process was rapidly reached equilibrium within 20 minutes. The DBP precursors removal efficiency decreased with the increasing pH value from 4 to 10. Hydrophobic compounds (humic acid and fulvic acid are more sensitive to MGO, whereas hydrophilic and nitrogenous compounds (aromatic proteins are more insensitive. MGO could be regenerated by using 20% (v/v ethanol and, the DBP precursors removal efficiency can stay stable after five cycles. These results indicate that MGO can be utilized as a promising adsorbent for the removal of DBP precursors from natural surface water.

  11. High Performance Nitrous Oxide Analyzer for Atmospheric Research Project

    Data.gov (United States)

    National Aeronautics and Space Administration — This project targets the development of a highly sensitive gas sensor to monitor atmospheric nitrous oxide. Nitrous oxide is an important species in Earth science...

  12. Removal of disinfection by-product precursors with ozone-UV advanced oxidation process.

    Science.gov (United States)

    Chin, A; Bérubé, P R

    2005-05-01

    The efficacy of using ozone (O3), ultraviolet irradiation (UV) and the combined O3-UV advanced oxidation process (AOP) to remove 2 classes of disinfection by-product (DBP) precursors from raw surface water samples have been evaluated and compared. In particular, trihalomethane and haloacetic acids formation potentials were measured. Laboratory batch scale experiments were carried out as a function of ozone and UV dosage in order to study the removal kinetics. It is concluded that the combined O3-UV AOP is more effective than either the ozone or UV treatment alone. Ozone-UV AOP is capable of mineralizing up to 50% of the total organic carbon from the raw source water at an ozone dose of 0.62+/-0.019 mg O3/mL and a UV dose of 1.61 W s/cm2. In addition, O3-UV AOP can reduce trihalomethane formation potential by roughly 80% and haloacetic acids formation potential by roughly 70% at the same ozone and UV dosage.

  13. Occurrence of by-products of strong oxidants reacting with drinking water contaminants--scope of the problem.

    OpenAIRE

    Rice, R G; Gomez-Taylor, M

    1986-01-01

    This paper describes results of a detailed literature review of the organic and inorganic by-products that have been identified as being formed in aqueous solution with four of the strong oxidizing/disinfecting agents commonly employed in drinking water treatment. These agents are: chlorine, chlorine dioxide, chloramine, and ozone. Significant findings include the production of similar nonchlorinated organic oxidation products from chlorine, chlorine dioxide, and ozone. In addition, all three...

  14. A new atmospherically relevant oxidant of sulphur dioxide.

    Science.gov (United States)

    Mauldin, R L; Berndt, T; Sipilä, M; Paasonen, P; Petäjä, T; Kim, S; Kurtén, T; Stratmann, F; Kerminen, V-M; Kulmala, M

    2012-08-01

    Atmospheric oxidation is a key phenomenon that connects atmospheric chemistry with globally challenging environmental issues, such as climate change, stratospheric ozone loss, acidification of soils and water, and health effects of air quality. Ozone, the hydroxyl radical and the nitrate radical are generally considered to be the dominant oxidants that initiate the removal of trace gases, including pollutants, from the atmosphere. Here we present atmospheric observations from a boreal forest region in Finland, supported by laboratory experiments and theoretical considerations, that allow us to identify another compound, probably a stabilized Criegee intermediate (a carbonyl oxide with two free-radical sites) or its derivative, which has a significant capacity to oxidize sulphur dioxide and potentially other trace gases. This compound probably enhances the reactivity of the atmosphere, particularly with regard to the production of sulphuric acid, and consequently atmospheric aerosol formation. Our findings suggest that this new atmospherically relevant oxidation route is important relative to oxidation by the hydroxyl radical, at least at moderate concentrations of that radical. We also find that the oxidation chemistry of this compound seems to be tightly linked to the presence of alkenes of biogenic origin.

  15. Atmospheric oxidation capacity sustained by a tropical forest.

    Science.gov (United States)

    Lelieveld, J; Butler, T M; Crowley, J N; Dillon, T J; Fischer, H; Ganzeveld, L; Harder, H; Lawrence, M G; Martinez, M; Taraborrelli, D; Williams, J

    2008-04-10

    Terrestrial vegetation, especially tropical rain forest, releases vast quantities of volatile organic compounds (VOCs) to the atmosphere, which are removed by oxidation reactions and deposition of reaction products. The oxidation is mainly initiated by hydroxyl radicals (OH), primarily formed through the photodissociation of ozone. Previously it was thought that, in unpolluted air, biogenic VOCs deplete OH and reduce the atmospheric oxidation capacity. Conversely, in polluted air VOC oxidation leads to noxious oxidant build-up by the catalytic action of nitrogen oxides (NO(x) = NO + NO2). Here we report aircraft measurements of atmospheric trace gases performed over the pristine Amazon forest. Our data reveal unexpectedly high OH concentrations. We propose that natural VOC oxidation, notably of isoprene, recycles OH efficiently in low-NO(x) air through reactions of organic peroxy radicals. Computations with an atmospheric chemistry model and the results of laboratory experiments suggest that an OH recycling efficiency of 40-80 per cent in isoprene oxidation may be able to explain the high OH levels we observed in the field. Although further laboratory studies are necessary to explore the chemical mechanism responsible for OH recycling in more detail, our results demonstrate that the biosphere maintains a remarkable balance with the atmospheric environment.

  16. Utilization of a By-product Produced from Oxidative Desulfurization Process over Cs-Mesoporous Silica Catalysts

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Hyeonjoo; Jeong, Kwang Eun; Jeong, Soon-Yong; Park, Young-Kwon; Kim, Do Heui; Jeon, Jong Ki

    2011-02-28

    We investigated the use of Cs-mesoporous silica catalysts to upgrade a by-product of oxidative desulfurization (ODS). Cs-mesoporous silica catalysts were chaeacterized through N2 adsorption, XRD, CO2-temperature-programmed desorption, and XRF. Cs-mesoporous silica prepared by the direct incorporation method showed higher catalytic performance than a Cs/MCM-41 catalyst by impregnation method for the catalytic decomposition of sulfone compounds produced from ODS process.

  17. Utilization of a by-product produced from oxidative desulfurization process over Cs-mesoporous silica catalysts.

    Science.gov (United States)

    Kim, Hyeonjoo; Jeong, Kwang-Eun; Jeong, Soon-Yong; Park, Young-Kwon; Kim, Do Heui; Jeon, Jong-Ki

    2011-02-01

    We investigated the use of Cs-mesoporous silica catalysts to upgrade a by-product of oxidative desulfurization (ODS). Cs-mesoporous silica catalysts were characterized through N2 adsorption, XRD, CO2-temperature-programmed desorption, and XRF. Cs-mesoporous silica prepared by the direct incorporation method showed higher catalytic performance than a Cs/MCM-41 catalyst by impregnation method for the catalytic decomposition of sulfone compounds produced from ODS process. PMID:21456272

  18. Synthesis by-products from the Wacker oxidation of safrole in methanol using rho-benzoquinone and palladium chloride.

    Science.gov (United States)

    Cox, M; Klass, G

    2006-12-20

    This paper reports the identification of a number of by-products, which are produced during the Wacker oxidation of safrole to 3,4-methylenedioxyphenyl-2-propanone (MDP2P) using rho-benzoquinone and palladium chloride when methanol is utilised as the solvent. Also described is the retrieval of these compounds from illicit samples from a clandestine laboratory, which was uncovered in South Australia in September 2003.

  19. Atmospheric oxidation capacity sustained by a tropical forest

    NARCIS (Netherlands)

    Lelieveld, J.; Butler, T.; Crowley, J.N.; Dillon, T.J.; Fischer, H.; Ganzeveld, L.N.; Harder, H.; Lawrence, M.G.; Martinez, M.; Taraborelli, D.; Williams, J.

    2008-01-01

    Terrestrial vegetation, especially tropical rain forest, releases vast quantities of volatile organic compounds (VOCs) to the atmosphere1, 2, 3, which are removed by oxidation reactions and deposition of reaction products4, 5, 6. The oxidation is mainly initiated by hydroxyl radicals (OH), primarily

  20. OXIDATION BEHAVIOR OF KOVAR ALLOY IN CONTROLLED ATMOSPHERE

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    Controlled oxidation experiments were performed on Kovar alloy by changing oxi-dation atmosphere, temperature, and exposure time to produce films with different oxide type and thickness. The results indicated that single Fe3O4 and single FeO were respectively obtained when Kovar alloy was oxidized in N2-2.31%H2O-0.95%H2 at 500℃ and in N2-2.31%H2O-O.5%H2 at 1000℃, and all kinetic curves followed linear relation; mixed oxides of FeO and Fe3O4 formed when Kovar was oxidized in N2-2.31%H2O at 1000℃, and parabolic kinetics were obeyed. Analysis of metal-lographic cross section of oxides indicated that oxygen diffusion inward through the oxide scale is responsible for intergranular oxide, which had formed beneath the oxide scales when the oxide products were mixed oxides of FeO and Fe3O4, and which did not occur when the oxide was single FeO or Fe3O4. The oxidation model was also established.

  1. Formation of halogenated disinfection by-products in cobalt-catalyzed peroxymonosulfate oxidation processes in the presence of halides.

    Science.gov (United States)

    Xie, Weiping; Dong, Wei; Kong, Deyang; Ji, Yuefei; Lu, Junhe; Yin, Xiaoming

    2016-07-01

    Sulfate radicals (SO4(-)) generated by activation of peroxymonosulfate (PMS) and persulfate (PS) are highly oxidative and applied to degrade various organic pollutants. This research was designed to investigate formation of halogenated by-products in Co(2+) activated PMS process in the presence of halides and natural organic matter (NOM). It was revealed that no halogenated by-products were detected in the presence of Cl(-) while 189 μg/L bromoform and 100.7 μg/L dibromoacetic acid (DBAA) were found after 120 h when 2 mg/L NOM, 0.1 mM Br(-), 1.0 mM PMS, and 5 μL Co(2+) were present initially. These products are known as disinfection by-products (DBPs) since they are formed in water disinfection processes. Formation of DBPs was even more significant in the absence of Co(2+). The data indicate that both PMS and SO4(-) can transform Br(-) to reactive bromine species which react with NOM to form halogenated by-products. Less DBP formation in Co(2+)-PMS systems was due to the further destruction of DBPs by SO4(-). More DBPs species including chlorinated ones were detected in the presence of both Cl(-) and Br(-). However, more brominated species produced than chlorinate ones generally. The total DBP yield decreased with the increase of Cl(-) content when total halides kept constant. This is one of the few studies that demonstrate the formation of halogenated DBPs in Co(2+)/PMS reaction systems, which should be taken into consideration in the application of SO4(-) based oxidation technologies. PMID:27093695

  2. Heterogeneous Photocatalytic Oxidation of Atmospheric Trace Contaminants

    Science.gov (United States)

    Ollis, David F.

    1996-01-01

    Heterogeneous photocatalysis involves the use of a light-activated catalyst at room temperature in order to carry out a desired reaction. In the presence of molecular oxygen, illumination of the n-type semiconductor oxide titanium dioxide (TiO2) provides for production of highly active forms of oxygen, such as hydroxyl radicals, which are able to carry out the complete oxidative destruction of simple hydrocarbons such as methane, ethane, ethylene, propylene, and carbon monoxide. This broad oxidation potential, coupled with the ability with sufficient residence time to achieve complete oxidation of simple hydrocarbon contaminants to carbon dioxide and water, indicated that heterogeneous photocatalysis should be examined for its potential for purification of spacecraft air. If a successful catalyst and photoreactor could be demonstrated at the laboratory level, such results would allow consideration of photocatalysts as a partial or complete replacement of adsorption systems, thereby allowing for reduction in lift-off weight of a portion of the life support system for the spacecraft, or other related application such as a space station or a conventional commercial aircraft. The present research was undertaken to explore this potential through achievement of the following plan of work: (a) ascertain the intrinsic kinetics of conversion of pollutants of interest in spacecraft, (b) ascertain the expected lifetime of catalysts through examination of most likely routes of catalyst deactivation and regeneration (c) model and explore experimentally the low pressure drop catalytic monolith, a commercial configuration for automotive exhaust control (d) examine the kinetics of multicomponent conversions. In the recent course of this work, we have also discovered how to increase catalyst activity via halide promotion which has allowed us to achieve approximately 100% conversion of an aromatic contaminant (toluene) in a very short residence time of 5-6 milliseconds.

  3. Control of disinfection by-product formation using ozone-based advanced oxidation processes.

    Science.gov (United States)

    Chen, Kuan-Chung; Wang, Yu-Hsiang

    2012-01-01

    The effects of ozone dosage, water temperature and catalyst addition in an ozonation-fluidized bed reactor (O3/FBR) on treated water quality and on the control of chlorinated and ozonated disinfection by-products (DBPs) were investigated. A biofiltration column was used to evaluate its removal efficiency on biodegradable organic matter and to reduce DBP formation. The Dong-Gang River, polluted by agricultural and domestic wastewater in Pingtung, Taiwan, was used as the water source. The treated water quality in terms of dissolved organic carbon (DOC), biodegradable DOC, ultraviolet absorbance at 254 nm (UV254) and specific UV absorbance (SUVA) improved with increasing ozone and catalyst dosages. Catalytic ozonation was more effective than ozonation alone at reducing the formation of DBPs at a given dosage. Experimental results show that water temperature had little effect on the treated water quality with the O3/FBR system used in this study (p > 0.05). The combination of O3/FBR and the biofiltration process effectively decreased the amount ofDBP precursors. The concentration of total trihalomethanes (TTHMs) was less than the maximum contaminant level (MCL) requirement, which is 80 microg/L, for all treated waters and the concentration of five haloacetic acids (HAA5) fell below 60 microg/L with an ozone dosage higher than 2.5 mg/L.

  4. Cobalt catalyzed peroxymonosulfate oxidation of tetrabromobisphenol A: Kinetics, reaction pathways, and formation of brominated by-products.

    Science.gov (United States)

    Ji, Yuefei; Kong, Deyang; Lu, Junhe; Jin, Hao; Kang, Fuxing; Yin, Xiaoming; Zhou, Quansuo

    2016-08-01

    Degradation of tetrabromobisphenol A (TBBPA), a flame retardant widely spread in the environment, in Co(II) catalyzed peroxymonosulfate (PMS) oxidation process was systematically explored. The second-order-rate constant for reaction of sulfate radical (SO4(-)) with TBBPA was determined to be 5.27×10(10)M(-1)s(-1). Apparently, degradation of TBBPA showed first-order kinetics to the concentrations of both Co(II) and PMS. The presence of humic acid (HA) and bicarbonate inhibited TBBPA degradation, most likely due to their competition for SO4(-). Degradation of TBBPA was initiated by an electron abstraction from one of the phenolic rings. Detailed transformation pathways were proposed, including β-scission of isopropyl bridge, phenolic ring oxidation, debromination and coupling reactions. Further oxidative degradation of intermediates in Co(II)/PMS process yielded brominated disinfection by-products (Br-DBPs) such as bromoform and brominated acetic acids. Evolution profile of Br-DBPs showed an initially increasing and then decreasing pattern with maximum concentrations occurring around 6-10h. The presence of HA enhanced the formation of Br-DBPs significantly. These findings reveal potentially important, but previously unrecognized, formation of Br-DBPs during sulfate radical-based oxidation of bromide-containing organic compounds that may pose toxicological risks to human health. PMID:27107323

  5. The oxidation and surface speciation of indium and indium oxides exposed to atmospheric oxidants

    Science.gov (United States)

    Detweiler, Zachary M.; Wulfsberg, Steven M.; Frith, Matthew G.; Bocarsly, Andrew B.; Bernasek, Steven L.

    2016-06-01

    Metallic indium and its oxides are useful in electronics applications, in transparent conducting electrodes, as well as in electrocatalytic applications. In order to understand more fully the speciation of the indium and oxygen composition of the indium surface exposed to atmospheric oxidants, XPS, HREELS, and TPD were used to study the indium surface exposed to water, oxygen, and carbon dioxide. Clean In and authentic samples of In2O3 and In(OH)3 were examined with XPS to provide standard spectra. Indium was exposed to O2 and H2O, and the ratio of O2 - to OH- in the O1s XPS region was used to monitor oxidation and speciation of the surface. HREELS and TPD indicate that water dissociates on the indium surface even at low temperature, and that In2O3 forms at higher temperatures. Initially, OH- is the major species at the surface. Pure In2O3 is also OH- terminated following water exposure. Ambient pressure XPS studies of water exposure to these surfaces suggest that high water pressures tend to passivate the surface, inhibiting extensive oxide formation.

  6. The Mantle-Atmosphere Connection: Oxidation of the Atmosphere through Mantle Convection

    Science.gov (United States)

    Lee, K. K. M.; Gu, T.; Li, M.; McCammon, C. A.

    2015-12-01

    Earth's mantle connects the surface with the deep interior through convection, and the evolution of its redox state will affect the distribution of siderophile elements1, recycling of refractory isotopes2 and the oxidation state of the atmosphere through volcanic outgassing3. The rise of oxygen in atmosphere, i.e., the Great Oxidation Event (G.O.E.) occurred ~2.4 billion years ago (Ga)4. However, multiple lines of evidence point to biological oxygen production well before 2.4 Ga5; while chromium isotopes in iron formations indicates a decline of atmospheric oxygen about 1.88 Ga6. In contrast to the fluctuation of atmospheric oxygen, vanadium in Archean mantle lithosphere suggests that the mantle redox state has been constant for ~3.5 Ga7. Indeed, the redox state of the deep Earth's interior is not well constrained8 and its effect on mantle dynamics is unknown. Here we show a redox-induced density difference affects mantle convection and may potentially cause the oxidation of the upper mantle. From two synthetic enstatite chondritic samples with identical bulk compositions but formed under different oxygen fugacities (fO2) compressed to lower mantle pressures and temperatures, we find Al2O3 forms its own phase separate from the dominant Mg-silicate perovskite phase (i.e., bridgmanite9) in the more reduced composition, in contrast to a more Al-rich, bridgmanite-dominated assemblage for a more oxidized starting composition. As a result, the reduced material is ~1-1.5% denser than the oxidized material. Geodynamical numerical simulations show that the redox-induced density difference could lead to an increased oxidation of Earth's upper mantle but is buffered by slow mixing with more reduced material through hot upwellings, which will potentially affect mantle redox and rise of oxygen in atmosphere.

  7. UV-based advanced oxidation processes for the treatment of odour compounds: efficiency and by-product formation.

    Science.gov (United States)

    Zoschke, Kristin; Dietrich, Norman; Börnick, Hilmar; Worch, Eckhard

    2012-10-15

    The occurrence of the taste and odour compounds geosmin and 2-methyl isoborneol (2-MIB) affects the organoleptic quality of raw waters from drinking water reservoirs worldwide. UV-based oxidation processes for the removal of these substances are an alternative to adsorption and biological processes, since they additionally provide disinfection of the raw water. We could show that the concentration of geosmin and 2-MIB could be reduced by VUV irradiation and the combination of UV irradiation with ozone and hydrogen peroxide in pure water and water from a drinking water reservoir. The figure of merit EE/O is an appropriate tool to compare the AOPs and showed that VUV and UV/O(3) yielded the lowest treatment costs for the odour compounds in pure and raw water, respectively. Additionally, VUV irradiation with addition of ozone, generated by the VUV lamp, was evaluated. The generation of ozone and the irradiation were performed in a single reactor system using the same low-pressure mercury lamp, thereby reducing the energy consumption of the treatment process. The formation of the undesired by-products nitrite and bromate was investigated. The combination of VUV irradiation with ozone produced by a VUV lamp avoided the formation of relevant concentrations of the by-products. The internal generation of ozone is capable to produce ozone concentrations sufficient to reduce EE/O below 1 kWh m(-3) and without the risk of the formation of nitrite or bromate above the maximum contaminant level.

  8. Removal of precursors for disinfection by-products (Dbps)--differences between ozone- and OH-radical-induced oxidation.

    Science.gov (United States)

    Kleiser, G; Frimmel, F H

    2000-06-22

    Pre-oxidation is often applied to reduce the formation of disinfection by-products (DBPs). The aim of pre-oxidation is to remove the centers of natural organic matter (NOM) which are responsible for the formation of DBPs. In this paper, the differences between ozone- and OH-radical-induced oxidation to remove DBP-precursors are compared. The experiments were done with water of the River Ruhr (Germany) with a concentration of dissolved organic carbon (DOC) of 2 mg/l. Ozonation was able to remove DBP precursors selectively. After application of an absorbed ozone mass of 1.5 mg/mg DOC, a reduction in the formation potential for (THM-FP) and in the formation potential for organic halogen adsorbable on activated carbon (AOX-FP) down to 68 and 73% of the initial concentration was achieved, respectively. A removal of NOM was not achieved using absorbed ozone masses between 0.5 and 1.5 mg/mg DOC. In the hydrogen peroxide/UV process, in which OH-radicals are the reactive species, an increase in the THM concentration was measured after application of this process with short irradiation times. The maximum value of the THM-FP was 20% higher than the initial THM-FP. After an irradiation time of 1,050 min and a hydrogen peroxide consumption of 5.6 mg/l, the THM-FP and AOX-FP decreased to 75 and 71% of the initial formation potential, respectively. There was no selective removal of DBP precursors because the DOC concentration decreased also to 75% of the initial DOC-concentration after 1,050 min of irradiation.

  9. Oxidative stability during storage of fish oil from filleting by-products of rainbow trout (Oncorhynchus mykiss) is largely independent of the processing and production temperature

    DEFF Research Database (Denmark)

    Honold, Philipp; Nouard, Marie-Louise; Jacobsen, Charlotte

    2016-01-01

    be used to produce high quality fish oil. In this study, the oxidative stability of fish oil produced from filleting by-products was evaluated. The oil was produced from conventional or organic fish (low and high omega-3 fatty acid content) at different temperatures (70 and 90°C). The oxidative stability...

  10. Catalytic oxidation of CS2 over atmospheric particles and oxide catalysts

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    The catalytic oxidization of CS2 over atmospheric particles and some oxide catalysts was explored through FT-IR, MS and a fixed-bed stainless steel reactor. The results show that at mospheric particles and some oxide catalysts exhibited considerable oxidizing activities for CS2 at ambient temperature. The reaction products are mainly COS and elemental sulfur, even CO2 on some catalysts. Among the catalysts, CaO has the strongest catalytic activity for oxidizing CS2. Fe2O3 is weaker than CaO. The catalytic activity for AI2O3 reduces considerably compared with the former two catalysts, and SiO2 the weakest. Atmospheric particle samples' catalytic activity is be tween Fe2O3's and AI2O3's. The atmospheric particle sample collected mainly consists of Ca(AI2Si2O8)· 4H2O, which is also the main component of cement. COS, the main product, is formed by the catalytic oxidization of CS2 with adsorbed “molecular” oxygen over the catalysts' surfaces. The concentration of adsorbed oxygen over catalysts' surfaces may be the key factor contributed to the oxidizing activity. It is indicated that CS2 could be catalytically oxidized over at mospheric particles, which induced that this reaction may be another important source of atmos pheric COS from CS2.

  11. Metal catalyzed atmospheric oxidation reactions. A challenge to coordination chemists

    Energy Technology Data Exchange (ETDEWEB)

    Coichev, N. (Sao Paulo Univ., SP (Brazil). Inst. de Quimica); Van Eldik, R. (Universitaet Witten/Herdecke (Germany))

    1994-01-01

    Oxidation reactions of SO[sub x] and NO[sub y] species in the aqueous phase can play an important role in atmospheric chemistry and are of major environmental concern. The auto-oxidation processes are known to be catalyzed by trace metal ions and complexes. An overview of the most important reactions in metal catalyzed autoxidation processes is presented. Attention is given to the oxidation of the SO[sub x] and NO[sub y] species separately, as well as to the combined chemistry that results from the interaction of SO[sub x] and NO[sub y] species in the absence and presence of metal ions. Our work has revealed a fascinating redox cycling of the metal ions and complexes during such autoxidation processes, which has turned out to present quite a challenge to coordination chemists. (authors). 118 refs., 4 figs., 1 tab.

  12. Co-Mg-Al oxides issued of hydrotalcite precursors for total oxidation of volatile organic compounds. Identification and toxicological impact of the by-products

    Energy Technology Data Exchange (ETDEWEB)

    Gennequin, C.; Kouassi, S.; Tidahy, L.; Cousin, R.; Lamonier, J.F.; Garcon, G.; Shirali, P.; Cazier, F.; Aboukais, A.; Siffert, St. [Universite Lille Nord de France, 59 - Lille (France); Gennequin, C.; Kouassi, S.; Tidahy, L.; Cousin, R.; Lamonier, J.F.; Garcon, G.; Shirali, P.; Aboukais, A.; Siffert, St. [ULCO, UCEIV, MREI, 59 - Dunkerque (France); Cazier, F. [ULCO, CCM, MREI, 59 - Dunkerque (France)

    2010-05-15

    Catalysts based on Co-Mg-Al, which were used for the total oxidation of toluene, were synthesized by using the hydrotalcite pathway. The calcination allowed us to obtain various mixed oxide types (i.e. Co{sub 3}O{sub 4}, Co{sub 2}AlO{sub 4} or CoAl{sub 2}O{sub 4}), presenting meso-pores of about 8 nm and high specific surface areas. The solids were tested for the total oxidation of toluene and showed a total selectivity in CO{sub 2} and H{sub 2}O for 100% of toluene conversion. However, studies using diffuse reflectance infrared 'operando' and GC-MS allowed us to identify intermediary by-products stemming from the catalytic oxidation of toluene: benzene and small quantities of benzaldehyde, styrene and acetophenone. In order to contribute to the improvement of the current scientific knowledge on volatile organic compound (VOC) toxicity in humans, the lung toxicity of toluene, benzene or their association was determined by using a human epithelial lung cell model (i.e. L132 cell line). VOC cytotoxicity was studied with three complementary methods: the enzymatic activity of extracellular lactate dehydrogenase (LDH), the enzymatic activity of mitochondrial dehydrogenase (mDH), and the incorporation of 5-Bromodeoxyuridine (5-BrdU). Taken together, these results showed the occurrence of adverse effects, notably reported by significant increases in LDH activity in cell culture supernatants, 24 hours after L132 cell exposure not only to toluene alone or benzene alone, but also to their association. This original approach allowed us to integrate some toxicological parameters to help the choice of new-dedicated catalysts for the oxidative conversion of VOC. (authors)

  13. Co-Mg-Al oxides issued of hydrotalcite precursors for total oxidation of volatile organic compounds. Identification and toxicological impact of the by-products

    International Nuclear Information System (INIS)

    Catalysts based on Co-Mg-Al, which were used for the total oxidation of toluene, were synthesized by using the hydrotalcite pathway. The calcination allowed us to obtain various mixed oxide types (i.e. Co3O4, Co2AlO4 or CoAl2O4), presenting meso-pores of about 8 nm and high specific surface areas. The solids were tested for the total oxidation of toluene and showed a total selectivity in CO2 and H2O for 100% of toluene conversion. However, studies using diffuse reflectance infrared 'operando' and GC-MS allowed us to identify intermediary by-products stemming from the catalytic oxidation of toluene: benzene and small quantities of benzaldehyde, styrene and acetophenone. In order to contribute to the improvement of the current scientific knowledge on volatile organic compound (VOC) toxicity in humans, the lung toxicity of toluene, benzene or their association was determined by using a human epithelial lung cell model (i.e. L132 cell line). VOC cytotoxicity was studied with three complementary methods: the enzymatic activity of extracellular lactate dehydrogenase (LDH), the enzymatic activity of mitochondrial dehydrogenase (mDH), and the incorporation of 5-Bromodeoxyuridine (5-BrdU). Taken together, these results showed the occurrence of adverse effects, notably reported by significant increases in LDH activity in cell culture supernatants, 24 hours after L132 cell exposure not only to toluene alone or benzene alone, but also to their association. This original approach allowed us to integrate some toxicological parameters to help the choice of new-dedicated catalysts for the oxidative conversion of VOC. (authors)

  14. Formation of iodinated disinfection by-products during oxidation of iodide-containing waters with chlorine dioxide.

    Science.gov (United States)

    Ye, Tao; Xu, Bin; Lin, Yi-Li; Hu, Chen-Yan; Lin, Lin; Zhang, Tian-Yang; Gao, Nai-Yun

    2013-06-01

    This study was to explore the formation of iodinated disinfection by-products (I-DBPs), including iodoform (CHI3), iodoacetic acid (IAA) and triiodoacetic acid (TIAA), when iodide-containing artificial synthesized waters and raw waters are in contact with chlorine dioxide (ClO2). Among the investigated I-DBPs, CHI3 was the major species during ClO2 oxidation in artificial synthesized waters. Impact factors were evaluated, including the concentrations of ClO2, iodide (I(-)), dissolved organic carbon (DOC) and pH. Formation of CHI3, IAA and TIAA followed an increasing and then decreasing pattern with increased ClO2 or DOC concentration. I-DBPs yield was significantly affected by solution pH. High concentrations of I-DBPs were generated under circumneutral conditions with the maximum formation at pH 8. The increase of I(-) concentration can increase I-DBPs yields, but the increment was suppressed when I(-) concentration was higher than 50 μM. When 100 μg/L I(-)and ClO2 (7.5-44.4 μM) were spiked to the raw water samples from Yangshupu and Minhang drinking water treatment plant, certain amounts of CHI3 and IAA were found under pH 7 and the concentrations were strongly correlated with ClO2 dosage and water qualities, however, no TIAA was detected. Finally, we investigated I-DBPs formation of 18 model compounds, including 4 carboxylic acids, 5 phenols and 8 amino acids, treating with ClO2 when I(-) was present. Results showed that most of these model compounds could form a considerable amount of I-DBPs, especially for propanoic acid, butanoic acid, resorcinol, hydroquinone, alanine, glutamic acid, phenylalanine and serine.

  15. Can Highly Oxidized Organics Contribute to Atmospheric New Particle Formation?

    Science.gov (United States)

    Ortega, Ismael K; Donahue, Neil M; Kurtén, Theo; Kulmala, Markku; Focsa, Cristian; Vehkamäki, Hanna

    2016-03-10

    Highly oxidized organic molecules may play a critical role in new-particle formation within Earth's atmosphere along with sulfuric acid, which has long been considered as a key compound in this process. Here we explore the interactions of these two partners, using quantum chemistry to find the formation free energies of heterodimers and trimers as well as the fastest evaporation rates of (2,2) tetramers. We find that the heterodimers are more strongly bound than pure sulfuric acid dimers. Their stability correlates well with the oxygen to carbon ratio of the organics, their volatility, and the number of hydrogen bonds formed. Most of the stable trimers contain one sulfuric acid and two organics (1,2), whereas many (2,2) tetramers evaporate quickly, probably due to the stability of (1,2) clusters. This finding agrees with recent experimental studies that show how new-particle formation involving oxidized organics and sulfuric acid may be rate-limited by activation of (1,2) trimers, confirming the importance of this process in the atmosphere.

  16. Pathways for the Oxidation of Sarin in Urban Atmospheres

    Energy Technology Data Exchange (ETDEWEB)

    Gerald E. Streit; James E. Bossert; Jeffrey S. Gaffney; Jon Reisner; Laurie A. McNair; Michael Brown; Scott Elliott

    1998-11-01

    Terrorists have threatened and carried out chemicalhiological agent attacks on targets in major cities. The nerve agent sarin figured prominently in one well-publicized incident. Vapors disseminating from open containers in a Tokyo subway caused thousands of casualties. High-resolution tracer transport modeling of agent dispersion is at hand and will be enhanced by data on reactions with components of the urban atmosphere. As a sample of the level of complexity currently attainable, we elaborate the mechanisms by which sarin can decompose in polluted air. A release scenario is outlined involving the passage of a gas-phase agent through a city locale in the daytime. The atmospheric chemistry database on related organophosphorus pesticides is mined for rate and product information. The hydroxyl,radical and fine-mode particles are identified as major reactants. A review of urban air chernistry/rnicrophysics generates concentration tables for major oxidant and aerosol types in both clean and dirty environments. Organic structure-reactivity relationships yield an upper limit of 10-1' cm3 molecule-' S-* for hydrogen abstraction by hydroxyl. The associated midday loss time scale could be as little as one hour. Product distributions are difficult to define but may include nontoxic organic oxygenates, inorganic phosphorus acids, sarin-like aldehydes, and nitrates preserving cholinergic capabilities. Agent molecules will contact aerosol surfaces in on the order of minutes, with hydrolysis and side-chain oxidation as likely reaction channels.

  17. Study of organic pollutants oxidation by atmospheric plasma discharge

    Science.gov (United States)

    Gumuchian, Diane; Cavadias, Simeon; Duten, Xavier; Tatoulian, Michael; da Costa, Patrick; Ognier, Stephanie

    2013-09-01

    Ozonation is one of the usual steps in water treatment processes. However, some organic molecules (acetic acid) cannot be decomposed during ozonation. In that context, we are developing an Advanced Oxidation Process based on the use of a needle plate discharge at atmospheric pressure. The process is a reactor with a plasma discharge between a high voltage electrode and the solution in controlled atmosphere. Characterizations of the plasma obtained in different atmospheres were carried out (Optical Emission Spectroscopy, iCCD camera observations, etc). The efficiency of the process was evaluated by the percentage of degradation of the model-pollutant, measured by liquid chromatography analysis. Treatments in nitrogen lead to the formation of NOx species that decrease the efficiency of the process. Indeed, NOx lead to the consumption of actives species created. Treatments in argon are the most efficient. Two hypotheses are considered: (i) metastable argon participates to the degradation of acetic acid or to the formation of radicals (ii) discharges in argon lead to the formation of many streamers of low energy that increase the interface plasma/solution.

  18. Atmospheric pressure plasma enhanced chemical vapor deposition of zinc oxide and aluminum zinc oxide

    International Nuclear Information System (INIS)

    Zinc oxide (ZnO) and aluminum-doped zinc oxide (AZO) thin films were deposited via atmospheric pressure plasma enhanced chemical vapor deposition. A second-generation precursor, bis(1,1,1,5,5,5-hexafluoro-2,4-pentanedionato)(N,N′-diethylethylenediamine) zinc, exhibited significant vapor pressure and good stability at one atmosphere where a vaporization temperature of 110 °C gave flux ∼ 7 μmol/min. Auger electron spectroscopy confirmed that addition of H2O to the carrier gas stream mitigated F contamination giving nearly 1:1 metal:oxide stoichiometries for both ZnO and AZO with little precursor-derived C contamination. ZnO and AZO thin film resistivities ranged from 14 to 28 Ω·cm for the former and 1.1 to 2.7 Ω·cm for the latter. - Highlights: • A second generation precursor was utilized for atmospheric pressure film growth. • Addition of water vapor to the carrier gas stream led to a marked reduction of ZnF2. • Carbonaceous contamination from the precursor was minimal

  19. Combined atmospheric oxidant capacity and increased levels of exhaled nitric oxide

    Science.gov (United States)

    Yang, Changyuan; Li, Huichu; Chen, Renjie; Xu, Wenxi; Wang, Cuicui; Tse, Lap Ah; Zhao, Zhuohui; Kan, Haidong

    2016-07-01

    Nitrogen dioxide and ozone are two interrelated oxidative pollutants in the atmosphere. Few studies have evaluated the health effects of combined oxidant capacity (O x ). We investigated the short-term effects of O x on fractional exhaled nitric oxide (FeNO), a well-established biomarker for airway inflammation, in a group of chronic obstructive pulmonary disease patients. Real-time concentrations of O x were obtained by calculating directly the sum of nitrogen dioxide and ozone. Linear mixed-effect models were applied to explore the acute effects of O x on FeNO levels. Short-term exposure to Ox was significantly associated with elevated FeNO. This effect was strongest in the first 24 h after exposure, and was robust to the adjustment of PM2.5. A 10 μg m‑3 increase in 24 h average concentrations of O x was associated with 4.28% (95% confidence interval: 1.19%, 7.37%) increase in FeNO. The effect estimates were statistically significant only among males, elders, and those with body mass index ≥24 kg m‑2, a comorbidity, higher educational attainment, or moderate airflow limitation. This analysis demonstrated an independent effect of O x on respiratory inflammation, and suggested that a single metric O x might serve as a preferable indicator of atmospheric oxidative capacity in further air pollution epidemiological studies.

  20. Kinetics of the oxidation of Zn foils in air atmosphere

    Energy Technology Data Exchange (ETDEWEB)

    Baca, R; Martinez, J [Centro de Investigacion de Dispositivos Semiconductores, BUAP, Puebla. C.P. 72570 (Mexico); Kryshtab, T [Departamento de Ciencias de Materiales, ESFM - IPN, Mexico D.F (Mexico); Juarez, G; Solache, H; Andraca, J; Garcia, O; Pena-Sierra, R, E-mail: rbaca02006@yahoo.com.mx

    2010-02-15

    The formation kinetics of ZnO thin films grown by oxidation of polycrystalline Zn foils in air atmosphere at temperatures below the melting point is reported. Previous to the oxidation process the Zn foils were polished to produce mirror-like finished surfaces. The growth rate of the ZnO films was monitored by ellipsometric measurements. The growth rate of the ZnO films under 100 nm follows a linear and parabolic behavior in accordance with previously reported studies. The thicknesses of the films strongly influence the appearance of the final produced ZnO surface. The ZnO films surfaces with thicknesses less than 100 nm resulted uniform with low rms roughness. However as the films become thicker the rms roughness increased and a uniform distribution of whiskers was observed. X-ray diffraction and photoluminescence (PL) studies were done on the ZnO films to find out their structural and optical characteristics. PL spectra on the films are composed by two main bands; a weak near-band gap in the ultraviolet region and a strong but well defined green band. A discussion is included on the origins of the observed PL spectra.

  1. Global atmospheric model for mercury including oxidation by bromine atoms

    Directory of Open Access Journals (Sweden)

    C. D. Holmes

    2010-12-01

    Full Text Available Global models of atmospheric mercury generally assume that gas-phase OH and ozone are the main oxidants converting Hg0 to HgII and thus driving mercury deposition to ecosystems. However, thermodynamic considerations argue against the importance of these reactions. We demonstrate here the viability of atomic bromine (Br as an alternative Hg0 oxidant. We conduct a global 3-D simulation with the GEOS-Chem model assuming gas-phase Br to be the sole Hg0 oxidant (Hg + Br model and compare to the previous version of the model with OH and ozone as the sole oxidants (Hg + OH/O3 model. We specify global 3-D Br concentration fields based on our best understanding of tropospheric and stratospheric Br chemistry. In both the Hg + Br and Hg + OH/O3 models, we add an aqueous photochemical reduction of HgII in cloud to impose a tropospheric lifetime for mercury of 6.5 months against deposition, as needed to reconcile observed total gaseous mercury (TGM concentrations with current estimates of anthropogenic emissions. This added reduction would not be necessary in the Hg + Br model if we adjusted the Br oxidation kinetics downward within their range of uncertainty. We find that the Hg + Br and Hg + OH/O3 models are equally capable of reproducing the spatial distribution of TGM and its seasonal cycle at northern mid-latitudes. The Hg + Br model shows a steeper decline of TGM concentrations from the tropics to southern mid-latitudes. Only the Hg + Br model can reproduce the springtime depletion and summer rebound of TGM observed at polar sites; the snowpack component of GEOS-Chem suggests that 40% of HgII deposited to snow in the Arctic is transferred to the ocean and land reservoirs, amounting to a net deposition flux to the Arctic of 60 Mg a−1. Summertime events of depleted Hg0 at Antarctic sites due to subsidence are much better simulated by

  2. Global atmospheric model for mercury including oxidation by bromine atoms

    Directory of Open Access Journals (Sweden)

    C. D. Holmes

    2010-08-01

    Full Text Available Global models of atmospheric mercury generally assume that OH and ozone are the main oxidants converting Hg0 to HgII and thus driving mercury deposition to ecosystems. However, thermodynamic considerations argue against the importance of these reactions. We demonstrate here the viability of atomic bromine (Br as an alternative Hg0 oxidant. We conduct a global 3-D simulation with the GEOS-Chem model assuming Br to be the sole Hg0 oxidant (Hg + Br model and compare to the previous version of the model with OH and ozone as the sole oxidants (Hg + OH/O3 model. We specify global 3-D Br concentration fields based on our best understanding of tropospheric and stratospheric Br chemistry. In both the Hg + Br and Hg + OH/O3 models, we add an aqueous photochemical reduction of HgII in cloud to impose a tropospheric lifetime for mercury of 6.5 months against deposition, as needed to reconcile observed total gaseous mercury (TGM concentrations with current estimates of anthropogenic emissions. This added reduction would not be necessary in the Hg + Br model if we adjusted the Br oxidation kinetics downward within their range of uncertainty. We find that the Hg + Br and Hg + OH/O3 models are equally capable of reproducing the spatial distribution of TGM and its seasonal cycle at northern mid-latitudes. The Hg + Br model shows a steeper decline of TGM concentrations from the tropics to southern mid-latitudes. Only the Hg + Br model can reproduce the springtime depletion and summer rebound of TGM observed at polar sites; the snowpack component of GEOS-Chem suggests that 40% of HgII deposited to snow in the Arctic is transferred to the ocean and land reservoirs, amounting to a net deposition flux of 60 Mg a−1. Summertime events of depleted Hg0 at Antarctic sites due to subsidence are much better simulated by the Hg + Br model. Model

  3. Nitrous oxide and carbon dioxide emissions during initial decomposition of animal by-products applied as fertilisers to soils.

    NARCIS (Netherlands)

    Cayuela, M.L.; Velthof, G.L.; Mondini, C.; Sinicco, T.; Groenigen, van J.W.

    2010-01-01

    The recycling of organic wastes as soil amendments is notably promoted in sustainable agricultural systems. However, for many animal by-products approved by organic farming regulations little is known about their effects on the greenhouse gas balance of the soil, in particular on N2O emissions. In t

  4. Pineapple by-product and canola oil as partial fat replacers in low-fat beef burger: Effects on oxidative stability, cholesterol content and fatty acid profile.

    Science.gov (United States)

    Selani, Miriam M; Shirado, Giovanna A N; Margiotta, Gregório B; Rasera, Mariana L; Marabesi, Amanda C; Piedade, Sonia M S; Contreras-Castillo, Carmen J; Canniatti-Brazaca, Solange G

    2016-05-01

    The effect of freeze-dried pineapple by-product and canola oil as fat replacers on the oxidative stability, cholesterol content and fatty acid profile of low-fat beef burgers was evaluated. Five treatments were performed: conventional (CN, 20% fat) and four low-fat formulations (10% fat): control (CT), pineapple by-product (PA), canola oil (CO), and pineapple by-product and canola oil (PC). Low-fat cooked burgers showed a mean cholesterol content reduction of 9.15% compared to the CN. Canola oil addition improved the fatty acid profile of the burgers, with increase in the polyunsaturated/saturated fatty acids ratio and decrease in the n-6/n-3 ratio, in the atherogenic and thrombogenic indexes. The oxidative stability of the burgers was affected by the vegetable oil addition. However, at the end of the storage time (120 days), malonaldehyde values of CO and PC were lower than the threshold for the consumer's acceptance. Canola oil, in combination with pineapple by-product, can be considered promising fat replacers in the development of healthier burgers.

  5. A spectroscopic study of ethylene destruction and by-product generation using a three-stage atmospheric packed-bed plasma reactor

    Energy Technology Data Exchange (ETDEWEB)

    Huebner, M.; Roepcke, J. [INP Greifswald, Felix-Hausdorff-Str. 2, 17489 Greifswald (Germany); Guaitella, O.; Rousseau, A. [LPP, Ecole Polytechnique, UPMC, Universite Paris Sud-11, CNRS, Palaiseau (France)

    2013-07-21

    Using a three-stage dielectric packed-bed plasma reactor at atmospheric pressure, the destruction of ethylene, a typical volatile organic compound, and the generation of major by-products have been studied by means of Fourier Transform Infrared Spectroscopy. A test gas mixture air at a gas flow of 1 slm containing 0.12% humidity with 0.1% ethylene has been used. In addition to the fragmentation of the precursor gas, the evolution of the concentration of ten stable reaction products, CO, CO{sub 2}, O{sub 3}, NO{sub 2}, N{sub 2}O, HCN, H{sub 2}O, HNO{sub 3}, CH{sub 2}O, and CH{sub 2}O{sub 2} has been monitored. The concentrations of the by-products range between 5 ppm, in the case of NO{sub 2}, and 1200 ppm, for H{sub 2}O. By the application of three sequentially working discharge cells at a frequency of f = 4 kHz and voltage values between 9 and 12 kV, a nearly complete decomposition of C{sub 2}H{sub 4} could be achieved. Furthermore, the influence of the specific energy deposition (SED) on the destruction process has been studied and the maximum value of SED was about 900 J l{sup -1}. The value of the characteristic energy {beta}, characterizing the energy efficiency of the ethylene destruction in the reactor, was found to be 330 J l{sup -1}. It was proven that the application of three reactor stages suppresses essentially the production of harmful by-products as formaldehyde, formic acid, and NO{sub 2} compared to the use of only one or two stages. Based on the multi-component detection, the carbon balance of the plasma chemical conversion of ethylene has been analyzed. The dependence of the fragmentation efficiencies of ethylene (R{sub F}(C{sub 2}H{sub 4}) = 5.5 Multiplication-Sign 10{sup 19} molecules J{sup -1}) and conversion efficiencies to the produced molecular species (R{sub C} = (0.1-3) Multiplication-Sign 10{sup 16} molecules J{sup -1}) on the discharge conditions could be estimated in the multistage plasma reactor.

  6. Quantification and human health risk assessment of by-products of photo catalytic oxidation of ethylbenzene, xylene and toluene in indoor air of analytical laboratories.

    Science.gov (United States)

    Dhada, Indramani; Sharma, Mukesh; Nagar, Pavan Kumar

    2016-10-01

    The by-products of TiO2-based photocatalytic oxidation (PCO) of ethylbenze, p,m-xylene, o-xylene and toluene (EXT) in vapour phase and those adsorbed on the catalyst surface (solid phase) were identified and quantified on GC/GC-MS. A factor was developed in terms of μg of by-product produced per mg of EXT removed per sq-meter surface area of catalyst for estimating the mass of by-products produced. The by-products quantified were: acetone, hexane, cyclohexane, benzene, crotonaldehyde, toulene, 1,4-benzoquinone, benzaldehyde, phenol, benzylalcohol, cresol, hydroquinone and benzoic acid. The by-products accounted for 2.3-4.2% of the total mass of EXT treated. For treating concentrations of 220μg/m(3) (ethylbenzene), 260μg/m(3) (p,m-xylene), 260μg/m(3) (o-xylene) and 320μg/m(3) (toluene), at a flow rate of 7L/min for 12h in a laboratory of volume 195m(3), the estimated cancer risks of by-products to the occupants were 1.51×10(-6), 1.06×10(-6), 4.69×10(-7), and 1.58×10(-9) respectively. The overall hazard index (HI) of the by-products for EXT was of the order 10(-4); which is much less than desired level of 1.0. The estimated risks were within the acceptable level. This study has also suggested the photocatalytic degradation pathways for EX which are through formation of toluene. PMID:27208611

  7. Cl atom initiated oxidation of 1-alkenes under atmospheric conditions

    Science.gov (United States)

    Walavalkar, M.; Sharma, A.; Alwe, H. D.; Pushpa, K. K.; Dhanya, S.; Naik, P. D.; Bajaj, P. N.

    2013-03-01

    In view of the importance of the oxidation pathways of alkenes in the troposphere, and the significance of Cl atom as an oxidant in marine boundary layer (MBL) and polluted industrial atmosphere, the reactions of four 1-alkenes (C6-C9) with Cl atoms are investigated. The rate coefficients at 298 K are measured to be (4.0 ± 0.5), (4.4 ± 0.7), (5.5 ± 0.9) and (5.9 ± 1.7) × 10-10 cm3 molecule-1 s-1 for 1-hexene, 1-heptene, 1-octene and 1-nonene, respectively. The quoted errors include the experimental 2σ, along with the error in the reference rate coefficients. From the systematic increase in the rate coefficients with the number of carbon atoms, an approximate value for the average rate coefficient for hydrogen abstraction per CH2 group in alkenes is estimated to be (4.9 ± 0.3) × 10-11 cm3 molecule-1 s-1. Based on these rate coefficients, the contribution of Cl atom reactions towards the degradation of these molecules is found to be comparable to that of OH radical reactions, under MBL conditions. The products identified in gas phase indicate that Cl atom addition occurs mainly at the terminal carbon, leading to the formation of 1-chloro-2-ketones and 1-chloro-2-ols. The major gas phase products from the alkenyl radicals (formed by H atom abstraction) are different positional isomers of long chain enols and enones. A preference for dissociation leading to an allyl radical, resulting in aldehydes, lower by three carbon atoms, is indicated. The observed relative yields suggest that in general, the increased contribution of the reactions of Cl atoms towards degradation of 1-alkenes in NOx free air does not result in an increase in the generation of small aldehydes (carbon number < 4), including chloroethanal, as compared to that in the reaction of 1-butene.

  8. Stabilization of coacervate systems by products of abiogenic oxidation of low-molecular-weight compounds using the energy of. gamma. radiation

    Energy Technology Data Exchange (ETDEWEB)

    Evreinova, T.N.; Kuzin, A.M.; Kryukova, L.M.; Kameneva, T.G.; Khrust, Yu.R.

    1976-01-01

    The purpose of the study was to determine the possibility of stabilization of protein-carbohydrate and protein-nucleic acid systems by products of the abiogenic oxidation of pyrocatechol, pyrogallol, and o-dianisidine using the energy of gamma radiation. The protein-nucleic acid system was produced by mixing the following reagents: histone, DNA, acetate buffer, and a solution of oxidized compounds. The protein-carbohydrate system was produced by mixing the following reagents: histone, gum arabic, acetate buffer, and a solution of oxidized compounds. Results indicated that the stabilization of coacervate systems occurs when stabilizing low-molecular-weight compounds of the type of quinones and the imino form of o-dianisidine are included in them. These compounds may be formed under the action of physical factors without the participation of enzymes. (HLW)

  9. Molecular understanding of atmospheric particle formation from sulfuric acid and large oxidized organic molecules

    OpenAIRE

    Schobesberger, S.; Junninen, H.; BIANCHI, F.; Lonn, G.; M. Ehn; Lehtipalo, K.; Dommen, J; S. Ehrhart; Ortega, I.K.; A. Franchin; Nieminen, T.; Riccobono, F.; Hutterli, M.; J. Duplissy; Almeida, J

    2013-01-01

    The formation of nanoparticles by condensable vapors in the atmosphere influences radiative forcing and therefore climate. We explored the detailed mechanism of particle formation, in particular the role of oxidized organic molecules that arise from the oxidation of monoterpenes, a class of volatile organic compounds emitted from plants. We mimicked atmospheric conditions in a well-controlled laboratory setup and found that these oxidized organics form initial clusters directly with single su...

  10. Missing SO2 oxidant in the coastal atmosphere? – Evidence from high resolution measurements of OH and atmospheric sulfur compounds

    Directory of Open Access Journals (Sweden)

    H. Berresheim

    2014-01-01

    Full Text Available Diurnal and seasonal variations of gaseous sulfuric acid (H2SO4 and methane sulfonic acid (MSA were measured in N.E. Atlantic air at the Mace Head atmospheric research station during the years 2010 and 2011. The measurements utilized selected ion/chemical ionization mass spectrometry (SI/CIMS with a detection limit for both compounds of 4.3 × 10 4 cm−3 at 5 min signal integration. The H2SO4 and MSA gas-phase concentrations were analysed in conjunction with the condensational sink for both compounds derived from 3 nm–10 μm (diameter aerosol size distributions. Accommodation coefficients of 1.0 for H2SO4 and 0.12 for MSA were assumed leading to estimated atmospheric lifetimes of the order of 7 min and 25 min, respectively. With the SI/CIMS instrument in OH measurement mode alternating between OH signal and background (non-OH signal evidence was obtained for the presence of one or more unknown oxidants of SO2 in addition to OH. Depending on the nature of the oxidant(s their ambient concentration may be enhanced in the CIMS inlet system by additional production. The apparent unknown SO2 oxidant was additionally confirmed by direct measurements of SO2 in conjunction with calculated H2SO4 concentrations. The calculated concentrations were consistently lower than the measured concentrations by a factor 4.8 ± 3.4 when considering the oxidation of SO2 by OH as the only source of H2SO4. Both the OH and the background signal were also observed to increase significantly during daytime aerosol nucleation events, independent of the ozone photolysis frequency, J(O1D, and were followed by peaks in both H2SO4 and MSA concentrations. This suggests a strong relation between the unknown oxidant(s, OH chemistry, and the atmospheric photo-oxidation of biogenic iodine compounds. As to the identity of the oxidant(s, we have been able to exclude ClO, BrO, IO, and OIO as possible candidates based on ab initio calculations. Stabilized Criegee intermediates (s

  11. Study on influence of native oxide and corrosion products on atmospheric corrosion of pure Al

    International Nuclear Information System (INIS)

    Highlights: •Corrosion products layer is only formed in coastal atmosphere. •In coastal atmosphere, rate controlling step is diffusion process. •In rural atmosphere, rate controlling step is charge transfer process. •Pitting area increases greatly in coastal site, but slightly in rural site. -- Abstract: Effects of native oxide and corrosion products on atmospheric corrosion of aluminium in rural and coastal sites were studied by electrochemical impedance spectroscopy (EIS), open-circuit potential (OCP) and scanning electron microscope (SEM) techniques after outdoor exposure. In the rural atmosphere, only the compact, adhesive native oxide layer exists, and the rate controlling step is diffusion process, while in the coastal atmosphere, another loose, inadhesive corrosion products layer exists, and a charge transfer process controls the corrosion process. The pitting area in the coastal atmosphere increases over time more obviously than that in the rural atmosphere

  12. Advances of study on atmospheric methane oxidation (consumption) in forest soil

    Institute of Scientific and Technical Information of China (English)

    WANG Chen-rui; SHI Yi; YANG Xiao-ming; WU Jie; YUE Jin

    2003-01-01

    Next to CO2, methane (CH4) is the second important contributor to global warming in the atmosphere and global atmospheric CH4 budget depends on both CH4 sources and sinks. Unsaturated soil is known as a unique sink for atmospheric CH4 in terrestrial ecosystem. Many comparison studies proved that forest soil had the biggest capacity of oxidizing atmospheric CH4 in various unsaturated soils. However, up to now, there is not an overall review in the aspect of atmospheric CH4 oxidation (consumption) in forest soil. This paper analyzed advances of studies on the mechanism of atmospheric CH4 oxidation, and related natural factors (Soil physical and chemical characters, temperature and moisture, ambient main greenhouse gases concentrations, tree species, and forest fire) and anthropogenic factors (forest clear-cutting and thinning, fertilization, exogenous aluminum salts and atmospheric deposition, adding biocides, and switch of forest land use) in forest soils. It was believed that CH4 consumption rate by forest soil was limited by diffusion and sensitive to changes in water status and temperature of soil. CH4 oxidation was also particularly sensitive to soil C/N, Ambient CO2, CH4 and N2O concentrations, tree species and forest fire. In most cases, anthropogenic disturbances will decrease atmospheric CH4 oxidation, thus resulting in the elevating of atmospheric CH4. Finally, the author pointed out that our knowledge of atmospheric CH4 oxidation (consumption) in forest soil was insufficient. In order to evaluate the contribution of forest soils to atmospheric CH4 oxidation and the role of forest played in the process of global environmental change, and to forecast the trends of global warming exactly, more researchers need to studies further on CH4 oxidation in various forest soils of different areas.

  13. The Autistic Phenotype Exhibits a Remarkably Localized Modification of Brain Protein by Products of Free Radical-Induced Lipid Oxidation

    Directory of Open Access Journals (Sweden)

    Teresa A. Evans

    2008-01-01

    Full Text Available Oxidative damage has been documented in the peripheral tissues of autism patients. In this study, we sought evidence of oxidative injury in autistic brain. Carboxyethyl pyrrole (CEP and iso[4]levuglandin (iso[4]LGE2-protein adducts, that are uniquely generated through peroxidation of docosahexaenoate and arachidonate-containing lipids respectively, and heme oxygenase-1 were detected immunocytochemically in cortical brain tissues and by ELISA in blood plasma. Significant immunoreactivity toward all three of these markers of oxidative damage in the white matter and often extending well into the grey matter of axons was found in every case of autism examined. This striking threadlike pattern appears to be a hallmark of the autistic brain as it was not seen in any control brain, young or aged, used as controls for the oxidative assays. Western blot and immunoprecipitation analysis confirmed neurofilament heavy chain to be a major target of CEP-modification. In contrast, in plasma from 27 autism spectrum disorder patients and 11 age-matched healthy controls we found similar levels of plasma CEP (124.5 ± 57.9 versus 110.4 ± 30.3 pmol/mL, iso[4]LGE2 protein adducts (16.7 ± 5.8 versus 13.4 ± 3.4 nmol/mL, anti-CEP (1.2 ± 0.7 versus 1.2 ± 0.3 and anti-iso[4]LGE2 autoantibody titre (1.3 ± 1.6 versus 1.0 ± 0.9, and no differences between the ratio of NO2Tyr/Tyr (7.81 E-06 ± 3.29 E-06 versus 7.87 E-06 ± 1.62 E-06. These findings provide the first direct evidence of increased oxidative stress in the autistic brain. It seems likely that oxidative injury of proteins in the brain would be associated with neurological abnormalities and provide a cellular basis at the root of autism spectrum disorders.

  14. Oxidation Products of Biogenic Emissions Contribute to Nucleation of Atmospheric Particles

    OpenAIRE

    Riccobono, F.; Schobesberger, S.; Scott, CE; Dommen, J; Ortega, IK; L. Rondo; Almeida, J; Amorim, A.; BIANCHI, F.; Breitenlechner, M.; David, A.(CERN, European Organization for Nuclear Research, Geneva, Switzerland); Downard, A.; Dunne, EM; J. Duplissy; S. Ehrhart

    2014-01-01

    Atmospheric new-particle formation affects climate and is one of the least understood atmospheric aerosol processes. The complexity and variability of the atmosphere has hindered elucidation of the fundamental mechanism of new-particle formation from gaseous precursors. We show, in experiments performed with the CLOUD (Cosmics Leaving Outdoor Droplets) chamber at CERN, that sulfuric acid and oxidized organic vapors at atmospheric concentrations reproduce particle nucleation rates observed in ...

  15. Nitric oxide and nitrous oxide emission from Hungarian forest soils; link with atmospheric N-deposition

    Directory of Open Access Journals (Sweden)

    L. Horváth

    2005-06-01

    Full Text Available Studies of forest nitrogen (N budgets generally measure inputs to the atmosphere in wet and dry precipitation and outputs via hydrologic export. Although denitrification has been shown to be important in many wetland ecosystems, emission of nitrogen oxides from forest soils is an important, and often overlooked, component of an ecosystem nitrogen budget. During one year (2002-2003, emissions of nitric oxide (NO and nitrous oxide (N2O were measured from Sessile oak and Norway spruce forest soils in northeast Hungary. Accumulation in small static chambers followed by gas chromatography-mass spectrometry detection was used for the estimation of N2O emission flux. Because there are rapid chemical reactions of NO and ozone, small dynamic chambers were used for in situ NO flux measurements. Average soil emissions of NO were 1.2 and 2.1 µgNm-2h-1, and for N2O were 15 and 20 µgNm-2h-1, for spruce and oak soils, respectively. The previously determined nitrogen balance between the atmosphere and the forest ecosystem was re-calculated using these soil emission figures. The total (dry + wet atmospheric N-deposition to the soil was 1.42 and 1.59gNm-2yr-1 for spruce and oak, respectively, while the soil emissions are 0.14 and 0.20 gNm-2yr-1. Thus, about 10-13% of N compounds deposited to the soil, mostly as NH3/NH4+ and HNO3/NO3-, are transformed in the soil and emitted back to the atmosphere, mostly as a greenhouse gas (N2O.

  16. Avocado by-products as inhibitors of color deterioration and lipid and protein oxidation in raw porcine patties subjected to chilled storage.

    Science.gov (United States)

    Rodríguez-Carpena, J G; Morcuende, D; Estévez, M

    2011-10-01

    Processing of avocados generates an important amount of by-products such as peels and seeds that are rich in bioactive substances with proven radical suppressing activities. The objective of this study was to evaluate the effectiveness of peel and seed extracts from two avocado varieties-'Hass' and 'Fuerte'-as inhibitors of lipid and protein oxidation and color deterioration of raw porcine patties during chilled storage (4 °C/15 days). Avocado extracts significantly (pHass' extracts. Patties treated with avocado extracts had significantly lower amounts of TBA-RS than control ones throughout the storage. 'Hass' avocado extracts significantly inhibited the formation of protein carbonyls in chilled patties at day 15. The present results highlight the potential usage of extracts from avocado by-products as ingredients for the production of muscle foods with enhanced quality traits.

  17. Ozone oxidation of antidepressants in wastewater –Treatment evaluation and characterization of new by-products by LC-QToFMS

    Directory of Open Access Journals (Sweden)

    Lajeunesse André

    2013-01-01

    Full Text Available Abstract Background The fate of 14 antidepressants along with their respective N-desmethyl metabolites and the anticonvulsive drug carbamazepine was examined in a primary sewage treatment plant (STP and following advanced treatments with ozone (O3. The concentrations of each pharmaceutical compound were determined in raw sewage, effluent and sewage sludge samples by LC-MS/MS analysis. The occurrence of antidepressant by-products formed in treated effluent after ozonation was also investigated. Results Current primary treatments using physical and chemical processes removed little of the compounds (mean removal efficiency: 19%. Experimental sorption coefficients (Kd of each studied compounds were also calculated. Sorption of venlafaxine, desmethylvenlafaxine, and carbamazepine on sludge was assumed to be negligible (log Kd ≤ 2, but higher sorption behavior can be expected for sertraline (log Kd ≥ 4. Ozonation treatment with O3 (5 mg/L led to a satisfactory mean removal efficiency of 88% of the compounds. Screening of the final ozone-treated effluent samples by high resolution-mass spectrometry (LC-QqToFMS did confirm the presence of related N-oxide by-products. Conclusion Effluent ozonation led to higher mean removal efficiencies than current primary treatment, and therefore represented a promising strategy for the elimination of antidepressants in urban wastewaters. However, the use of O3 produced by-products with unknown toxicity.

  18. Meat composition, fatty acid profile and oxidative stability of meat from broilers supplemented with pomegranate (Punica granatum L.) by-products.

    Science.gov (United States)

    Ahmed, Sonia Tabasum; Islam, Md Manirul; Bostami, A B M Rubayet; Mun, Hong-Seok; Kim, Ye-Jin; Yang, Chul-Ju

    2015-12-01

    The effects of diets supplemented with four levels (0%, 0.5%, 1.0% and 2.0%) of pomegranate by-product (PB) on meat composition, fatty acid profile and oxidative stability of broiler meat were evaluated. The crude protein and moisture contents increased, whereas ether extract in breast and thigh meat and cholesterol in breast meat decreased in response to dietary PB supplementation (p<0.05). In breast and thigh meat, the sum of saturated fatty acids was lower, while the sum of mono-unsaturated and n-3 fatty acids were higher, alongside lower n-6/n-3 ratio in the 1.0% and 2.0% PB supplemented group (p<0.05). The TBARS values and pH of breast and thigh meat were reduced in the PB supplemented groups (p<0.05). Overall, the results presented herein indicate that supplementation of diets with up to 2% pomegranate by-products improved the meat composition, fatty acid profile and reduced lipid oxidation of broiler meat. PMID:26041221

  19. Radioactive Fingerprinting of Microorganisms That Oxidize Atmospheric Methane in Different Soils

    OpenAIRE

    Roslev, Peter; Iversen, Niels

    1999-01-01

    Microorganisms that oxidize atmospheric methane in soils were characterized by radioactive labelling with 14CH4 followed by analysis of radiolabelled phospholipid ester-linked fatty acids (14C-PLFAs). The radioactive fingerprinting technique was used to compare active methanotrophs in soil samples from Greenland, Denmark, the United States, and Brazil. The 14C-PLFA fingerprints indicated that closely related methanotrophic bacteria were responsible for the oxidation of atmospheric methane in ...

  20. Linking activity, composition and seasonal dynamics of atmospheric methane oxidizers in a meadow soil

    OpenAIRE

    Shrestha, Pravin Malla; KAMMANN, Claudia; Lenhart, Katharina; Dam, Bomba; Liesack, Werner

    2011-01-01

    Microbial oxidation is the only biological sink for atmospheric methane. We assessed seasonal changes in atmospheric methane oxidation and the underlying methanotrophic communities in grassland near Giessen (Germany), along a soil moisture gradient. Soil samples were taken from the surface layer (0–10 cm) of three sites in August 2007, November 2007, February 2008 and May 2008. The sites showed seasonal differences in hydrological parameters. Net uptake rates varied seasonally between 0 and 7...

  1. The enhanced removal of carbonaceous and nitrogenous disinfection by-product precursors using integrated permanganate oxidation and powdered activated carbon adsorption pretreatment.

    Science.gov (United States)

    Chu, Wenhai; Yao, Dechang; Gao, Naiyun; Bond, Tom; Templeton, Michael R

    2015-12-01

    Pilot-scale tests were performed to reduce the formation of a range of carbonaceous and nitrogenous disinfection by-products (C-, N-DBPs), by removing or transforming their precursors, with an integrated permanganate oxidation and powdered activated carbon adsorption (PM-PAC) treatment process before conventional water treatment processes (coagulation-sedimentation-filtration, abbreviated as CPs). Compared with the CPs, PM-PAC significantly enhanced the removal of DOC, DON, NH3(+)-N, and algae from 52.9%, 31.6%, 71.3%, and 83.6% to 69.5%, 61.3%, 92.5%, and 97.5%, respectively. PM pre-oxidation alone and PAC pre-adsorption alone did not substantially reduce the formation of dichloroacetonitrile, trichloroacetonitrile, N-nitrosodimethylamine and dichloroacetamide. However, the PM-PAC integrated process significantly reduced the formation of both C-DBPs and N-DBPs by 60-90% for six C-DBPs and 64-93% for six N-DBPs, because PM oxidation chemically altered the molecular structures of nitrogenous organic compounds and increased the adsorption capacity of the DBP precursors, thus highlighting a synergistic effect of PM and PAC. PM-PAC integrated process is a promising drinking water technology for the reduction of a broad spectrum of C-DBPs and N-DBPs. PMID:26065622

  2. Visible light photo response from N-doped anodic niobium oxide after annealing in ammonia atmosphere

    International Nuclear Information System (INIS)

    Niobium oxide films with a thickness of approximately 165 nm were prepared by electrochemical anodization. These anodic oxide layers were then treated in an ammonia atmosphere at different temperatures and durations, and characterized with XRD, XPS, ToF-SIMS and photoelectrochemical methods. Under optimized conditions nitrogen doping of the niobium oxide films takes place, resulting in a distinct photo response in the visible range of light.

  3. Nitrogen atmosphere and natural antioxidants effect on muesli oxidation during long-time storage

    Directory of Open Access Journals (Sweden)

    Dorota Klensporf-Pawlik

    2009-03-01

    Full Text Available The effects of natural antioxidants from raspberry and black currant seeds and modified atmosphere packaging on muesli oxidative stability measured by monitoring volatile lipid oxidation products were evaluated. The effectiveness toward lipid oxidation was investigated during 10 months storage at ambient temperature. Both ethanolic extracts as well as nitrogen atmosphere influenced lipid oxidation rate in muesli measured by volatile compounds content. The most abundant lipid derived volatile compounds was hexanal. After storage, its concentration changed from 802 µg/kg to 9.8 mg/kg in muesli stored in air atmosphere, whereas in muesli stored in nitrogen atmosphere with raspberry seed extract addition it raised to 3.1 mg/kg. Although, both natural antioxidants rich in phenolic compounds, were effective towards lipid oxidation, the strongest inhibiting effect had modified atmosphere packaging. The addition of ethanolic extracts did not fortify its positive effect. Total concentration of volatile compounds in muesli after 10 months of storage was 19.6 mg/kg when stored in air and 13.7 and 11.8 mg/kg when stored with raspberry and black currant seeds extract addition respectively, while 9.8 mg/kg when stored in nitrogen atmosphere without antioxidants, and 9.7 and 9.9 mg/kg when stored with antioxidants mentioned above.

  4. Five pesticides decreased oxidation of atmospheric methane in a forest soil

    DEFF Research Database (Denmark)

    Priemé, Anders; Ekelund, Flemming

    2001-01-01

    We found that five tested pesticides (the insecticide Dimethoat 40 EC, the herbicide Tolkan, and the fungicides Tilt 250 EC, Tilt Top, and Corbel) decreased the oxidation of atmospheric methane in slurries from a Danish forest soil. Dimethoat 40 EC was the most toxic with an EC50 value (i...... the oxidation of atmospheric methane at concentrations expected in natural soil after application of the pesticides. Pesticides, therefore, may be partly responsible for the lowered methane oxidation rates in arable soils compared to forest soils....

  5. Insights into hydroxyl measurements and atmospheric oxidation in a California forest

    Directory of Open Access Journals (Sweden)

    J. Mao

    2012-03-01

    Full Text Available The understanding of oxidation in forest atmospheres is being challenged by measurements of unexpectedly large amounts of hydroxyl (OH. A significant number of these OH measurements were made by laser-induced fluorescence in low-pressure detection chambers (called Fluorescence Assay with Gas Expansion (FAGE using the Penn State Ground-based Tropospheric Hydrogen Oxides Sensor (GTHOS. We deployed a new chemical removal method to measure OH in parallel with the traditional FAGE method. The new method gives on average only 40–50% of the OH from the traditional method and this discrepancy is temperature-dependent. Evidence indicates that the new method measures atmospheric OH while the traditional method is affected by internally generated OH, possibly from oxidation of biogenic volatile organic compounds. The agreement between OH measured by this new technique and modeled OH suggests that oxidation chemistry in at least one forest atmosphere is better understood than previously thought.

  6. Oxidation Products of Biogenic Emissions Contribute to Nucleation of Atmospheric Particles

    CERN Document Server

    Riccobono, Francesco; Baltensperger, Urs; Worsnop, Douglas R; Curtius, Joachim; Carslaw, Kenneth S; Wimmer, Daniela; Wex, Heike; Weingartner, Ernest; Wagner, Paul E; Vrtala, Aron; Viisanen, Yrjö; Vaattovaara, Petri; Tsagkogeorgas, Georgios; Tomé, Antonio; Stratmann, Frank; Stozhkov, Yuri; Spracklen, Dominick V; Sipilä, Mikko; Praplan, Arnaud P; Petäjä, Tuukka; Onnela, Antti; Nieminen, Tuomo; Mathot, Serge; Makhmutov, Vladimir; Lehtipalo, Katrianne; Laaksonen, Ari; Kvashin, Alexander N.; Kürten, Andreas; Kupc, Agnieszka; Keskinen, Helmi; Kajos, Maija; Junninen, Heikki; Hansel, Armin; Franchin, Alessandro; Flagan, Richard C; Ehrhart, Sebastian; Duplissy, Jonathan; Dunne, Eimear M; Downard, Andrew; David, André; Breitenlechner, Martin; Bianchi, Federico; Amorim, Antonio; Almeida, João; Rondo, Linda; Ortega, Ismael K; Dommen, Josef; Scott, Catherine E; Vrtala, Aron; Santos, Filipe D; Schallhart, Simon; Seinfeld, John H; Sipila, Mikko; Donahue, Neil M; Kirkby, Jasper; Kulmala, Markku

    2014-01-01

    Atmospheric new-particle formation affects climate and is one of the least understood atmospheric aerosol processes. The complexity and variability of the atmosphere has hindered elucidation of the fundamental mechanism of new-particle formation from gaseous precursors. We show, in experiments performed with the CLOUD (Cosmics Leaving Outdoor Droplets) chamber at CERN, that sulfuric acid and oxidized organic vapors at atmospheric concentrations reproduce particle nucleation rates observed in the lower atmosphere. The experiments reveal a nucleation mechanism involving the formation of clusters containing sulfuric acid and oxidized organic molecules from the very first step. Inclusion of this mechanism in a global aerosol model yields a photochemically and biologically driven seasonal cycle of particle concentrations in the continental boundary layer, in good agreement with observations.

  7. High-Temperature, Dual-Atmosphere Corrosion of Solid-Oxide Fuel Cell Interconnects

    Science.gov (United States)

    Gannon, Paul; Amendola, Roberta

    2012-12-01

    High-temperature corrosion of ferritic stainless steel (FSS) surfaces can be accelerated and anomalous when it is simultaneously subjected to different gaseous environments, e.g., when separating fuel (hydrogen) and oxidant (air) streams, in comparison with single-atmosphere exposures, e.g., air only. This so-called "dual-atmosphere" exposure is realized in many energy-conversion systems including turbines, boilers, gasifiers, heat exchangers, and particularly in intermediate temperature (600-800°C) planar solid-oxide fuel cell (SOFC) stacks. It is generally accepted that hydrogen transport through the FSS (plate or tube) and its subsequent integration into the growing air-side surface oxide layer can promote accelerated and anomalous corrosion—relative to single-atmosphere exposure—via defect chemistry changes, such as increased cation vacancy concentrations, decreased oxygen activity, and steam formation within the growing surface oxide layers. Establishment of a continuous and dense surface oxide layer on the fuel side of the FSS can inhibit hydrogen transport and the associated effects on the air side. Minor differences in FSS composition, microstructure, and surface conditions can all have dramatic influences on dual-atmosphere corrosion behaviors. This article reviews high-temperature, dual-atmosphere corrosion phenomena and discusses implications for SOFC stacks, related applications, and future research.

  8. Oxidation Behaviour of Si3N4 Materials in Air and Nitrogen Atmosphere

    Institute of Scientific and Technical Information of China (English)

    ZHANGQitu; LINGZhida

    1999-01-01

    Si3N4 powder and hot-pressed Si3N4 ceramics added with Al2O3 are used for investigate their oxidation behvior in air and nitrogen atmosphere(with oxygen partial pressure PO2=1-10Pa),The oxidation products of Si3N4 are examined by chemical analysi,X-ray diffraction (XRD) and XPS method,Also, thermodynamic calculation is made to analyze oxidation behavior of Si3N4.The results show that only passive oxidation will occur when Si3N4 is oxidized in air at high temperature,whereas in N2 at high temperature,the active oxidation is dominant in spite of the existence of a little passive oxidation.

  9. Rapid changes in biomass burning aerosols by atmospheric oxidation

    OpenAIRE

    Vakkari, Ville; Beukes, Johan Paul; Tiitta, Petri; van Zyl, Pieter G.; Josipovic, Miroslav; Venter, Andrew D.; Jaars, Kerneels

    2014-01-01

    Primary and secondary aerosol particles originating from biomass burning contribute significantly to the atmospheric aerosol budget and thereby to both direct and indirect radiative forcing. Based on detailed measurements of a large number of biomass burning plumes of variable age in southern Africa, we show that the size distribution, chemical composition, single-scattering albedo, and hygroscopicity of biomass burning particles change considerably during the first 2–4 h of their...

  10. Mechanistic and kinetic studies on the OH-initiated atmospheric oxidation of fluoranthene

    International Nuclear Information System (INIS)

    The atmospheric oxidation of polycyclic aromatic hydrocarbons (PAHs) can generate toxic derivatives which contribute to the carcinogenic potential of particulate organic matter. In this work, the mechanism of the OH-initiated atmospheric oxidation of fluoranthene (Flu) was investigated by using high-accuracy molecular orbital calculations. All of the possible oxidation pathways were discussed, and the theoretical results were compared with the available experimental observation. The rate constants of the crucial elementary reactions were evaluated by the Rice–Ramsperger–Kassel–Marcus (RRKM) theory. The main oxidation products are a range of ring-retaining and ring-opening chemicals containing fluoranthols, fluoranthones, fluoranthenequinones, nitro-fluoranthenes, dialdehydes and epoxides. The overall rate constant of the OH addition reaction is 1.72 × 10−11 cm3 molecule−1 s−1 at 298 K and 1 atm. The atmospheric lifetime of Flu determined by OH radicals is about 0.69 days. This work provides a comprehensive investigation of the OH-initiated oxidation of Flu and should help to clarify its atmospheric conversion. - Highlights: • We studied a comprehensive mechanism of OH-initiated oxidation of fluoranthene. • We reported the formation pathways of fluoranthone, fluoranthenequinone and epoxide. • The rate constants of the crucial elementary steps were evaluated

  11. Contribution of dopants to sinterability of UO2 in reducing and oxidizing atmospheres

    International Nuclear Information System (INIS)

    The effects of dopants on sinterability of UO2 have been studied in hydrogen and CO2/CO mixture atmospheres. Ta2O5, TiO2 and Nb2O5 have been used as a sintering aid for UO2. The dopants were added as oxide powers at the level of 0.10 wt% of oxide, and in the case of the Ta2O5 and Nb2O5, a further addition was made. The dopants and UO2 powders were homogenized by attrition milling. The mixed powders were pressed with die wall lubrication and sintered in hydrogen at 1700degC for 4 hrs or in oxidizing atmosphere using controlled CO2/CO mixture at 1250degC for 5 hrs. The pellets sintered in oxidizing atmospheres were reduced in hydrogen at 1200degC for 2 hrs. In reducing atmosphere, both density and microstructure of UO2 are modified by the addition of dopant. The sintered density is increased with Ta addition up to 0.33 wt% and substantially decreased by high contents of Ta. The effects on the densification and the grain growth is apparent for the addition of 0.24 wt% niobia. For 0.1 wt% titania, the sintered density is decreased, but the grain size is increased. In oxidizing atmosphere, the effect of additives on densification occurred only a little. The grain size of Ta- and Nb-doped UO2 is decreased with increasing CO2/CO ratio, but that of Ti-doped UO2 is not changed. A large portion of second phase is observed in UO2 doped with 0.66 wt% Ta2O5 and 0.1 wt% TiO2 sintered in hydrogen atmosphere, but not observed in CO2/CO atmospheres. (author)

  12. Degradation of polyethylene induced by plasma in oxidizing atmospheres

    International Nuclear Information System (INIS)

    The garbage of polyethylene is not easily degradable in normal environmental conditions . The indiscriminate use of this polymer and the enormous quantity of garbage which is generated carries a damage to the environment due to its long life as waste. The objective of this work is to study the conditions in which can be carried out the degradation of polyethylene. A form of accelerating the degradation is exposing it to plasma with reactive atmospheres. In this work a study of surface modification of polyethylene by plasmas with discharges of direct current of oxygen and nitrogen is presented. (Author)

  13. OH regeneration from methacrolein oxidation investigated in the atmosphere simulation chamber SAPHIR

    OpenAIRE

    Fuchs, H; I.-H. Acir; Bohn, B.; Brauers, T.; H.-P. Dorn; R. Häseler; Hofzumahaus, A.; Holland, F.; Kaminski, M.; Li, X.; Lu, K.; A. Lutz; Nehr, S.; Rohrer, F.; Tillmann, R.

    2014-01-01

    Hydroxyl radicals (OH) are the most important reagent for the oxidation of trace gases in the atmosphere. OH concentrations measured during recent field campaigns in isoprene rich environments were unexpectedly large. A number of studies showed that unimolecular reactions of organic peroxy radicals (RO2) formed in the initial reaction step of isoprene with OH play an important role for the OH budget in the atmosphere at low mixing ratios of nitrogen monoxide...

  14. High Temperature Corrosion of Fe-C-S Cast Irons in Oxidizing and Sulfidizing Atmospheres

    Institute of Scientific and Technical Information of China (English)

    Thuan-Dinh NGUYEN; Dong-Bok LEE

    2008-01-01

    The corrosion behavior of spheroidal graphite and flake graphite cast irons was studied in oxidizing and sulfidizing atmospheres between 600 and 800℃ for 50 h. The corrosion rate in the sulfidizing atmosphere was faster than that in air above 700℃, due to the formation of the Feo.975S sulfide. The corrosion rate of the spheroidal graphite cast iron was similar to that of the flake graphite cast iron.

  15. Oxidation Effect on Pool Boiling Heat Transfer in Atmospheric Saturated Water

    Energy Technology Data Exchange (ETDEWEB)

    Son, Hong Hyun; Jeong, Uiju; Seo, Gwang Hyeok; Jeun, Gyoodong; Kim, Sung Joong [Hanyang Univ., Seoul (Korea, Republic of)

    2014-10-15

    During the hypothesized severe accidents, however, the modified nature of the oxidized outer surface of RPV may act as a significant heat transfer variable to achieve In-Vessel Retention through External Reactor Vessel Cooling (IVR-ERVC) strategy, which is the one of important mitigation strategies of severe accident to delay occurrence of critical heat flux (CHF). As well understood, the CHF is mainly affected by the two distinctive conditions classified to thermal hydraulic behavior of fluid system and surface characteristics. In this regard, a CHF test considering oxidation effect on the pool boiling heat transfer of the RPV outer surface has been proposed to evaluate realistic thermal margin of IVR-ERVC strategy. In this study, pool boiling heat transfer experiment was conducted under the condition of atmospheric saturated water. Oxidized surface characteristics were quantitatively evaluated with measurement of contact angle and roughness. In this study, oxide layer formation on the heated surface was investigated and experimentally simulated to find out its effect on the pool boiling CHF. Several SS316L substrates were oxidized in the corrosive environment under the condition of high temperature with different oxidation periods. Local pitting corrosion was observed on the heating surface in 5 days of short-term oxidation but a fully oxidized surface with somewhat uniform thickness, 1. Pool boiling heat transfer tests with the bare and oxidized heaters were conducted and major findings are summarized as follows: 1. Wettability in terms of the receding angle of the oxidized surface is enhanced regardless of the oxidation period. 2. Average roughness between the oxidized surfaces is almost the same in the range of nano-scale. 3. Effect of wettability and surface roughness on the CHF was negligible in the locally oxidized surface, which may be attributed to the presence of the disconnected porous channel. Unlike the local oxidation, fully oxidized surface shows

  16. NEW CATHODE MATERIALS FOR INERT AND OXIDIZING ATMOSPHERE PLASMA APPLICATION

    OpenAIRE

    Sadek, A; Kusumoto, K.; Ushio, M; Matsuda, F.

    1990-01-01

    This study has been carried out to develop new cathode materials for two types of thermionic cathode. First is concerning to the tungsten electrodes for the plasma furnace and welding torches. The second one is the electrodes for air plasma cutting torch. Tungsten electrodes activated with a single and combined additives of rare earth metal oxides, such as La2O3, Y2O3 and CeO2, are produced and pared with pure and thoriated tungsten electrode conventionally used, from the point of view of ele...

  17. ETCHING OF WRINKLED GRAPHENE OXIDE FILMS IN NOBLE GAS ATMOSPHERE UNDER UV IRRADIATION

    OpenAIRE

    ALEKSENSKII A.E.; VUL S.P.; DIDEIKIN A.T.; Sakharov, V. I.; SERENKOV I.T.; RABCHINSKII M.K.; AFROSIMOV V.V.

    2016-01-01

    We have studied the process of UV reduction of wrinkled grahpene oxide films, deposited on silicon substrate from ethanol suspension. In order to avoid destruction of graphene oxide via ozone formation from ambient air, samples were protected by argon atmosphere during UV irradiation. Using the analysis of back scattering spectra for medium energy ions, we have found that the UV irradiation mediated reduction process produced significantly decreased carbon content on the substrate surface. Th...

  18. Reactivity of E-butenedial with the major atmospheric oxidants

    Science.gov (United States)

    Martín, Pilar; Cabañas, Beatriz; Colmenar, Inmaculada; Salgado, María Sagrario; Villanueva, Florentina; Tapia, Araceli

    2013-05-01

    The degradation reactions of E-butenedial with OH and NO3 radicals and Cl atoms were investigated using a relative rate method. The experiments were carried out at ˜298 ± 1 K and an atmospheric pressure of N2 or synthetic air as the bath gas. Three different sampling/detection methods have been used for the study with Cl, OH and NO3: (1) Solid-Phase Microextraction and Gas Chromatography with Flame Ionization Detection (SPME/GC-FID), (2) ‘in situ’ with long-path Fourier Transform Infrared Spectroscopy (FTIR), and (3) Tenax solid adsorbent and Gas Chromatography with Mass Spectrometry (Tenax/GC-MS) as the detection system. The measured rate coefficients for E-butenedial (cm3 molecule-1 s-1) are as follows: (1.35 ± 0.29) × 10-10 for the Cl atom, (3.45 ± 0.34) × 10-11 for the OH radical and (1.70 ± 0.83) × 10-15 for the NO3 radical. For the reaction of Cl and NO3 these are the first rate coefficient data to be reported and in the case of OH the literature value is confirmed. This study confirms that the chemical structure of the organic substances does not influence on the reactivity with Cl, has a significant effect for OH reactions and is very important for NO3 reactions. Calculated atmospheric lifetimes are in the order of days for Cl and NO3 reactions and hours for OH. In the case of Cl atoms, a lifetime of 20 h is estimated in the early morning hours in urban coastal air. These shorter lifetimes imply that the degradation reactions of E-butenedial are of great importance because their reaction products are secondary pollutants that are involved in processes such as the formation of photochemical smog or peroxyacyl nitrates (PANs).

  19. Branching between fragmentation and functionalization pathways in the oxidation of atmospheric organics

    Science.gov (United States)

    Kroll, J. H.; Smith, J. D.; Wilson, K. R.; Worsnop, D. R.; Ahmed, M.; Leone, S. R.

    2008-12-01

    Oxidation reactions that affect the volatility of organics are of central importance to the chemistry of the troposphere, as they lead to the formation of secondary organic aerosol, and can change the properties or loadings of existing particulate matter via oxidative processing ("aging"). Atmospheric oxidation can decrease the vapor pressure of an organic compound by adding oxygen-containing functional groups (increasing its polarity), or increase vapor pressure by breaking carbon-carbon bonds (decreasing its molecular weight). Despite being a fundamental determinant of the changes to volatilities of atmospheric organics, the functionalization/fragmentation branching ratio is not well-constrained for large atmospheric organics, especially for highly oxidized ones. Here we present laboratory measurements of this branching ratio for the heterogeneous oxidation of particulate organics. Particles of pure squalane (a branched C30 alkane) are sent into a flow reactor and are rapidly oxidized by exposure to high levels of OH; particle size and composition are measured as a function of OH exposure using a scanning mobility particle sizer (SMPS) and high-resolution time-of-flight aerosol mass spectrometer (AMS). Oxidation reactions are found to decrease particle mass, indicating volatilization (from carbon-carbon bond breaking) and also to increase the oxygen/carbon (O/C) ratio of the particulate organics, indicating the addition of functional groups. The relative rates of these two processes allows for the determination of the branching ratio between fragmentation and functionalization. Functionalization is found to dominate the oxidation of the pure hydrocarbon, but the importance of fragmentation increases as the organics become increasingly oxidized. Fragmentation pathways appear to dominate for organics with O/C ratios above ~30%.

  20. Conventional methanotrophs are responsible for atmospheric methane oxidation in paddy soils

    Science.gov (United States)

    Cai, Yuanfeng; Zheng, Yan; Bodelier, Paul L. E.; Conrad, Ralf; Jia, Zhongjun

    2016-06-01

    Soils serve as the biological sink of the potent greenhouse gas methane with exceptionally low concentrations of ~1.84 p.p.m.v. in the atmosphere. The as-yet-uncultivated methane-consuming bacteria have long been proposed to be responsible for this `high-affinity' methane oxidation (HAMO). Here we show an emerging HAMO activity arising from conventional methanotrophs in paddy soil. HAMO activity was quickly induced during the low-affinity oxidation of high-concentration methane. Activity was lost gradually over 2 weeks, but could be repeatedly regained by flush-feeding the soil with elevated methane. The induction of HAMO activity occurred only after the rapid growth of methanotrophic populations, and a metatranscriptome-wide association study suggests that the concurrent high- and low-affinity methane oxidation was catalysed by known methanotrophs rather than by the proposed novel atmospheric methane oxidizers. These results provide evidence of atmospheric methane uptake in periodically drained ecosystems that are typically considered to be a source of atmospheric methane.

  1. Low-temperature sintering process for UO2 pellets in partially-oxidative atmosphere

    Institute of Scientific and Technical Information of China (English)

    YANG Xiao-dong; GAO Jia-cheng; WANG Yong; CHANG Xin

    2008-01-01

    Low-temperature sintering(LTS) experiments of UO2 pellets and their results were reported. Moreover, a routine process of LTS for UO2 pellets was primarily established. Being sintered at 1 400 ℃ for 3 h in a partially-oxidative atmosphere, the relative density of the pellet can be up to around 94%. Pellets with such a high density are of benefit for following-up reduction-sintering processes. Orthogonal test indicates that the importance of factors affecting the density decreases in the sequence of partial-oxidative sintering temperature and time, reduction-sintering time and temperature, and sintering atmosphere. It is found that it is helpful to introducing a small amount of water vapor into the sintering atmosphere during the latter stage. It is believed that it is the key factor to raise the O/U ratio of original powder in order to improve the properties of the low-temperature sintered pellets.

  2. Complexes and clusters of water relevant to atmospheric chemistry: H2O complexes with oxidants.

    Science.gov (United States)

    Sennikov, Petr G; Ignatov, Stanislav K; Schrems, Otto

    2005-03-01

    Experimental observations and data from quantum chemical calculations on complexes between water molecules and small, oxygen-containing inorganic species that play an important role as oxidants in the atmosphere (O(1D), O(3P), O2(X3sigmag), O2(b1sigmag+), O3, HO, HOO, HOOO, and H2O2) are reviewed, with emphasis on their structure, hydrogen bonding, interaction energies, thermodynamic parameters, and infrared spectra. In recent years, weakly bound complexes containing water have increasingly attracted scientific attention. Water in all its phases is a major player in the absorption of solar and terrestrial radiation. Thus, complexes between water and other atmospheric species may have a perceivable influence on the radiative balance and contribute to the greenhouse effect, even though their concentrations are low. In addition, they can play an important role in the chemistry of the Earth's atmosphere, particularly in the oxidation of trace gases. Apart from gas-phase complexes, the interactions of oxidants with ice surfaces have also received considerable advertency lately due to their importance in the chemistry of snow, ice clouds, and ice surfaces (e.g., ice shields in polar regions). In paleoclimate--respectively paleoenvironmental--studies, it is essential to understand the transfer processes from the atmosphere to the ice surface. Consequently, special attention is being paid here to the intercomparison of the properties of binary complexes and the complexes and clusters of more complicated compositions, including oxidants adsorbed on ice surfaces, where ice is considered a kind of large water cluster. Various facts concerning the chemistry of the Earth's atmosphere (concentration profiles and possible influence on radical reactions in the atmosphere) are discussed. PMID:15799459

  3. Carbon oxidation state as a metric for describing the chemistry of atmospheric organic aerosol

    Energy Technology Data Exchange (ETDEWEB)

    Massachusetts Institute of Technology; Kroll, Jesse H.; Donahue, Neil M.; Jimenez, Jose L.; Kessler, Sean H.; Canagaratna, Manjula R.; Wilson, Kevin R.; Altieri, Katye E.; Mazzoleni, Lynn R.; Wozniak, Andrew S.; Bluhm, Hendrik; Mysak, Erin R.; Smith, Jared D.; Kolb, Charles E.; Worsnop, Douglas R.

    2010-11-05

    A detailed understanding of the sources, transformations, and fates of organic species in the environment is crucial because of the central roles that organics play in human health, biogeochemical cycles, and Earth's climate. However, such an understanding is hindered by the immense chemical complexity of environmental mixtures of organics; for example, atmospheric organic aerosol consists of at least thousands of individual compounds, all of which likely evolve chemically over their atmospheric lifetimes. Here we demonstrate the utility of describing organic aerosol (and other complex organic mixtures) in terms of average carbon oxidation state (OSC), a quantity that always increases with oxidation, and is readily measured using state-of-the-art analytical techniques. Field and laboratory measurements of OSC , using several such techniques, constrain the chemical properties of the organics and demonstrate that the formation and evolution of organic aerosol involves simultaneous changes to both carbon oxidation state and carbon number (nC).

  4. Atmospheric oxidation mechanism of phenol initiated by OH radical.

    Science.gov (United States)

    Xu, Cui; Wang, Liming

    2013-03-21

    The gas-phase oxidation mechanism of phenol initiated by OH radical was investigated using DFT and ab initio calculations. The initiation of the reaction is dominated by OH addition to ortho-position, forming P2, which subsequently combines with O2 at the ipso-position to form P2-1-OO adduct. A concerted HO2 elimination process from P2-1-OO was found to be much faster than the common ring closure to bicyclic intermediates. The HO2 elimination process from P2-1-OO forms 2-hydroxy-3,5-cyclohexadienone (HCH) as the main product and is also responsible for the experimental fact that the rate constants for reaction between P2 and O2 are about 2 orders of magnitude higher than those between other aromatic-OH adducts and O2. It was speculated that HCH would isomerize to catechol, which is thermodynamically more stable than HCH and was the experimentally observed main product, possibly through heterogeneous processes. Reaction of P2 with NO2 proceeded by addition to form P2-n-NO2 (n = 1, 3, 5), followed by HONO elimination from P2-1/3-NO2 to form catechol. The barriers for HONO elimination and catechol formation are below the separate reactants P2 and NO2, being consistent with the experimental observation of catechol in the absence of O2, while H2O elimination from P2-1/3-NO2 to form 2-nitrophenol (2NP) is hindered by high barriers. The most likely pathway for 2NP is the reaction of phenoxy radical and NO2.

  5. Regional Air Quality Model Application of the Aqueous-Phase Photo Reduction of Atmospheric Oxidized Mercury by Dicarboxylic Acids

    Science.gov (United States)

    In most ecosystems, atmospheric deposition is the primary input of mercury. The total wet deposition of mercury in atmospheric chemistry models is sensitive to parameterization of the aqueous-phase reduction of divalent oxidized mercury (Hg2+). However, most atmospheric chemistry...

  6. Manganese oxide phases and morphologies: A study on calcination temperature and atmospheric dependence

    Directory of Open Access Journals (Sweden)

    Matthias Augustin

    2015-01-01

    Full Text Available Manganese oxides are one of the most important groups of materials in energy storage science. In order to fully leverage their application potential, precise control of their properties such as particle size, surface area and Mnx+ oxidation state is required. Here, Mn3O4 and Mn5O8 nanoparticles as well as mesoporous α-Mn2O3 particles were synthesized by calcination of Mn(II glycolate nanoparticles obtained through an economical route based on a polyol synthesis. The preparation of the different manganese oxides via one route facilitates assigning actual structure–property relationships. The oxidation process related to the different MnOx species was observed by in situ X-ray diffraction (XRD measurements showing time- and temperature-dependent phase transformations occurring during oxidation of the Mn(II glycolate precursor to α-Mn2O3 via Mn3O4 and Mn5O8 in O2 atmosphere. Detailed structural and morphological investigations using transmission electron microscopy (TEM and powder XRD revealed the dependence of the lattice constants and particle sizes of the MnOx species on the calcination temperature and the presence of an oxidizing or neutral atmosphere. Furthermore, to demonstrate the application potential of the synthesized MnOx species, we studied their catalytic activity for the oxygen reduction reaction in aprotic media. Linear sweep voltammetry revealed the best performance for the mesoporous α-Mn2O3 species.

  7. High Temperature Behavior of Oxidized Mild Steel in Dry and Wet Atmospheres

    International Nuclear Information System (INIS)

    During the hot rolling process, steels develop an oxide scale on their surface. This scale can affect the mechanical properties of the rolled steel and its surface aspect. The main problem comes from the mechanical integrity of the oxide scales which could delaminate or crack, leading eventually to later oxide incrustation within the steel. The objective of the present work is to qualify the mechanical integrity of the iron oxide scales during the hot rolling process. The laboratory experiments use a four point bending test to simulate the mechanical solicitation which takes place during the rolling sequence of the steel slabs. The oxide scales grow on a mild steel at 900 .deg. C under wet or dry atmosphere and the oxidized steel is then mechanically tested at 900 .deg. C or 700 .deg. C. The high temperature four point bending tests are completed with microstructural observations and with the record of acoustic emission to follow in-situ the mechanical damages of the oxide scales. The results show the role of water vapor which promotes the scale adherence, and the role of the temperature as the oxide are more damaged at 700 .deg. C than at 900 .deg. C

  8. Molecular understanding of atmospheric particle formation from sulfuric acid and large oxidized organic molecules

    Science.gov (United States)

    Schobesberger, Siegfried; Junninen, Heikki; Bianchi, Federico; Lönn, Gustaf; Ehn, Mikael; Lehtipalo, Katrianne; Dommen, Josef; Ehrhart, Sebastian; Ortega, Ismael K.; Franchin, Alessandro; Nieminen, Tuomo; Riccobono, Francesco; Hutterli, Manuel; Duplissy, Jonathan; Almeida, João; Amorim, Antonio; Breitenlechner, Martin; Downard, Andrew J.; Dunne, Eimear M.; Flagan, Richard C.; Kajos, Maija; Keskinen, Helmi; Kirkby, Jasper; Kupc, Agnieszka; Kürten, Andreas; Kurtén, Theo; Laaksonen, Ari; Mathot, Serge; Onnela, Antti; Praplan, Arnaud P.; Rondo, Linda; Santos, Filipe D.; Schallhart, Simon; Schnitzhofer, Ralf; Sipilä, Mikko; Tomé, António; Tsagkogeorgas, Georgios; Vehkamäki, Hanna; Wimmer, Daniela; Baltensperger, Urs; Carslaw, Kenneth S.; Curtius, Joachim; Hansel, Armin; Petäjä, Tuukka; Kulmala, Markku; Donahue, Neil M.; Worsnop, Douglas R.

    2013-01-01

    Atmospheric aerosols formed by nucleation of vapors affect radiative forcing and therefore climate. However, the underlying mechanisms of nucleation remain unclear, particularly the involvement of organic compounds. Here, we present high-resolution mass spectra of ion clusters observed during new particle formation experiments performed at the Cosmics Leaving Outdoor Droplets chamber at the European Organization for Nuclear Research. The experiments involved sulfuric acid vapor and different stabilizing species, including ammonia and dimethylamine, as well as oxidation products of pinanediol, a surrogate for organic vapors formed from monoterpenes. A striking resemblance is revealed between the mass spectra from the chamber experiments with oxidized organics and ambient data obtained during new particle formation events at the Hyytiälä boreal forest research station. We observe that large oxidized organic compounds, arising from the oxidation of monoterpenes, cluster directly with single sulfuric acid molecules and then form growing clusters of one to three sulfuric acid molecules plus one to four oxidized organics. Most of these organic compounds retain 10 carbon atoms, and some of them are remarkably highly oxidized (oxygen-to-carbon ratios up to 1.2). The average degree of oxygenation of the organic compounds decreases while the clusters are growing. Our measurements therefore connect oxidized organics directly, and in detail, with the very first steps of new particle formation and their growth between 1 and 2 nm in a controlled environment. Thus, they confirm that oxidized organics are involved in both the formation and growth of particles under ambient conditions. PMID:24101502

  9. Mechanistic studies on the OH-initiated atmospheric oxidation of selected aromatic hydrocarbons

    Energy Technology Data Exchange (ETDEWEB)

    Nehr, Sascha

    2012-07-01

    Benzene, toluene, the xylenes, and the trimethylbenzenes are among the most abundant aromatic trace constituents of the atmosphere mainly originating from anthropogenic sources. The OH-initiated atmospheric photo-oxidation of aromatic hydrocarbons is the predominant removal process resulting in the formation of O{sub 3} and secondary organic aerosol. Therefore, aromatics are important trace constituents regarding air pollution in urban environments. Our understanding of aromatic photo-oxidation processes is far from being complete. This work presents novel approaches for the investigation of OH-initiated atmospheric degradation mechanisms of aromatic hydrocarbons. Firstly, pulsed kinetic studies were performed to investigate the prompt HO{sub 2} formation from OH+ aromatic hydrocarbon reactions under ambient conditions. For these studies, the existing OH reactivity instrument, based on the flash photolysis/laser-induced fluorescence (FP/LIF) technique, was extended to the detection of HO{sub 2} radicals. The experimental design allows for the determination of HO{sub 2} formation yields and kinetics. Results of the pulsed kinetic experiments complement previous product studies and help to reduce uncertainties regarding the primary oxidation steps. Secondly, experiments with aromatic hydrocarbons were performed under atmospheric conditions in the outdoor atmosphere simulation chamber SAPHIR (Simulation of Atmospheric PHotochemistry In a large Reaction chamber) located at Forschungszentrum Juelich. The experiments were aimed at the evaluation of up-to-date aromatic degradation schemes of the Master Chemical Mechanism (MCMv3.2). The unique combination of analytical instruments operated at SAPHIR allows for a detailed investigation of HO{sub x} and NO{sub x} budgets and for the determination of primary phenolic oxidation product yields. MCMv3.2 deficiencies were identified and most likely originate from shortcomings in the mechanistic representation of ring

  10. Molecular understanding of atmospheric particle formation from sulfuric acid and large oxidized organic molecules

    CERN Document Server

    Schobesberger, Siegfried; Bianchi, Federico; Lönn, Gustaf; Ehn, Mikael; Lehtipalo, Katrianne; Dommen, Josef; Ehrhart, Sebastian; Ortega, Ismael K; Franchin, Alessandro; Nieminen, Tuomo; Riccobono, Francesco; Hutterli, Manuel; Duplissy, Jonathan; Almeida, João; Amorim, Antonio; Breitenlechner, Martin; Downard, Andrew J; Dunne, Eimear M; Flagan, Richard C; Kajos, Maija; Keskinen, Helmi; Kirkby, Jasper; Kupc, Agnieszka; Kürten, Andreas; Kurtén, Theo; Laaksonen, Ari; Mathot, Serge; Onnela, Antti; Praplan, Arnaud P; Rondo, Linda; Santos, Filipe D; Schallhart, Simon; Schnitzhofer, Ralf; Sipilä, Mikko; Tomé, António; Tsagkogeorgas, Georgios; Vehkamäki, Hanna; Wimmer, Daniela; Baltensperger, Urs; Carslaw, Kenneth S; Curtius, Joachim; Hansel, Armin; Petäjä, Tuukka; Kulmala, Markku; Donahue, Neil M; Worsnop, Douglas R

    2013-01-01

    Atmospheric aerosols formed by nucleation of vapors affect radiative forcing and therefore climate. However, the underlying mechanisms of nucleation remain unclear, particularly the involvement of organic compounds. Here, we present high-resolution mass spectra of ion clusters observed during new particle formation experiments performed at the Cosmics Leaving Outdoor Droplets chamber at the European Organization for Nuclear Research. The experiments involved sulfuric acid vapor and different stabilizing species, including ammonia and dimethylamine, as well as oxidation products of pinanediol, a surrogate for organic vapors formed from monoterpenes. A striking resemblance is revealed between the mass spectra from the chamber experiments with oxidized organics and ambient data obtained during new particle formation events at the Hyytiälä boreal forest research station. We observe that large oxidized organic compounds, arising from the oxidation of monoterpenes, cluster directly with single sulfuric acid molec...

  11. Conventional methanotrophs are responsible for atmospheric methane oxidation in paddy soils

    OpenAIRE

    Cai, Yuanfeng; Yan, Zheng; Bodelier, P. L. E.; Conrad, R.; Jia, Zhongjun

    2016-01-01

    Soils serve as the biological sink of the potent greenhouse gas methane with exceptionally low concentrations of ~1.84 p.p.m.v. in the atmosphere. The as-yet-uncultivated methane-consuming bacteria have long been proposed to be responsible for this ‘high-affinity’ methane oxidation (HAMO). Here we show an emerging HAMO activity arising from conventional methanotrophs in paddy soil. HAMO activity was quickly induced during the low-affinity oxidation of high-concentration methane. Activity was ...

  12. Direct measurements of nitric oxide height distribution in the middle atmosphere

    International Nuclear Information System (INIS)

    The [NO] distribution over the entire range of middle atmosphere altitudes (∼20-100 km) has been obtained in only one experiment involving measurement of solar radiation absorption in the infrared range; the measurements were performed aboard the orbital station Spacelab-1. This study presents results of the first direct rock measurements of the height distribution of nitric oxide in the range ∼30-90 km, performed by an RFI photoionization sensor

  13. Monitoring atmospheric nitrous oxide background concentrations at Zhongshan Station, east Antarctica.

    Science.gov (United States)

    Ye, Wenjuan; Bian, Lingen; Wang, Can; Zhu, Renbin; Zheng, Xiangdong; Ding, Minghu

    2016-09-01

    At present, continuous observation data for atmospheric nitrous oxide (N2O) concentrations are still lacking, especially in east Antarctica. In this paper, nitrous oxide background concentrations were measured at Zhongshan Station (69°22'25″S, 76°22'14″E), east Antarctica during the period of 2008-2012, and their interannual and seasonal characteristics were analyzed and discussed. The mean N2O concentration was 321.9nL/L with the range of 320.5-324.8nL/L during the five years, and it has been increasing at a rate of 0.29% year(-1). Atmospheric N2O concentrations showed a strong seasonal fluctuation during these five years. The concentrations appeared to follow a downtrend from spring to autumn, and then increased in winter. Generally the highest concentrations occurred in spring. This trend was very similar to that observed at other global observation sites. The overall N2O concentration at the selected global sites showed an increasing annual trend, and the mean N2O concentration in the Northern Hemisphere was slightly higher than that in the Southern Hemisphere. Our result could be representative of atmospheric N2O background levels at the global scale. This study provided valuable data for atmospheric N2O concentrations in east Antarctica, which is important to study on the relationships between N2O emissions and climate change. PMID:27593286

  14. Corrosion resistance of a steel under an oxidizing atmosphere in a fluid catalytic cracking regenerator

    Energy Technology Data Exchange (ETDEWEB)

    Caminha, Ieda [Instituto Nacional de Tecnologia (INT), Rio de Janeiro, RJ (Brazil). Lab. de Metalografia e de Dureza; Zeng, Chaoliu [Chinese Academy of Science, Shenyang (China). Inst. of Corrosion and Protection of Metals. State Key Lab. for Corrosion and Protection; Paes, Marcelo Piza [PETROBRAS, Rio de Janeiro, RJ (Brazil). Centro de Pesquisas (CENPES); Monteiro, Mauricio Jesus; Rizzo, Fernando [Pontificia Univ. Catolica do Rio de Janeiro, RJ (Brazil). Dept. de Ciencia dos Materiais e Metalurgia]. E-mail: rizzo@dcmm.puc-rio.br

    2004-03-01

    In the present work, the corrosion resistance of an ASTM A 387 G11 steel was evaluated under two conditions: an oxidizing atmosphere in a fluid catalytic cracking regenerator of a petroleum processing unit and a simulated atmosphere in the laboratory, at temperatures of 650 deg C and 700 deg C. The characterization of the phases present in the oxidized layer was carried out by X-ray diffraction (XRD), optical microscopy (OM) and scanning electron microscopy (SEM) with X-ray energy dispersive analysis (EDS). Severe corrosion was observed after exposure to both the real and simulated conditions, with formation of several iron oxides (Fe{sub 2}O{sub 3}, Fe{sub 3}O{sub 4} and Fe O) in the product scale layer, as well as a slight inner oxidation and sulfidation of chromium in the substrate. Internal nitridation of the silicon and the manganese was observed only in the real condition, probably related to the long-term exposure inside the regenerator. (author)

  15. Waiting ages for atmospheric oxygen: A titration hourglass and the oxidation of the solid Earth. (Invited)

    Science.gov (United States)

    Catling, D. C.; Claire, M.; Zahnle, K. J.

    2013-12-01

    Atmospheric O2 increased from less than 1 ppm to 0.2-2% at 2.45-2.22 Ga in the Great Oxidation Event (GOE). A minority opinion is that the GOE happened close to the time when oxygenic photosynthesis originated but evidence from the concentration of redox-sensitive elements in shales and their isotopes, as well as the setting and morphology of stromatolites supports the consensus view that oxygenic photosynthesis had originated by 2.8-2.7 Ga. Models show that O2 can be consumed rapidly by reductants in the Archean so that the air can remain anoxic even after photosynthesis began pumping out O2. Why did the world ultimately shift away from this balance? What conditions were needed to oxygenate the atmosphere in addition to oxygenic photosynthesis? A general principle is that a shift to an oxic environment from a reducing one requires net export of reductant. In planetary science, for example, the oxidation of the surfaces and atmospheres of other planets or satellites is universally attributed to the escape of hydrogen to space. Hydrogen escape explains the redness of Mars, several characteristics of the atmosphere of Venus, and the presence of tenuous O2 atmospheres on Ganymede, Europa, Rhea and Dione. For the Earth's rise of oxygen, many ideas focus on a decline in mantle or seafloor reductant fluxes (driven by internal geologic evolution) to the point where these fluxes were surpassed by biogenic oxygen fluxes. But for such a shift (without a role for hydrogen escape), the surface still has to export net reductant to the mantle. Such net export depends on the ratio of subducted ferric iron versus reduced carbon during the Archean, which remains poorly constrained. Over a decade ago, we proposed that rapid escape of hydrogen to space from the pre-GOE atmosphere would have gradually oxidized the Earth's surface and crust, accompanied by falling levels of atmospheric CH4 [1]. The idea is that Earth underwent a redox titration. A point would be reached where O2 became

  16. Laboratory investigations of the hydroxyl radical-initiated oxidation of atmospheric volatile organic compounds

    Science.gov (United States)

    Vimal, Deepali

    The hydroxyl radical (OH) is one of the most important oxidants in the atmosphere, because reaction with OH is the dominant atmospheric fate of most trace atmospheric species. OH is intimately involved in a complex non-linear photochemical pathway involving anthropogenic and biogenic emissions of volatile organic compounds (VOCs) and nitrogen oxides that are emitted from vehicular exhaust and industrial emissions. This chemistry generates secondary tropospheric ozone which is an important greenhouse gas as well as a component of photochemical smog. In addition, this chemistry leads to the formation of secondary organic aerosols in the atmosphere which have implications for public health and climate change. The focus of this dissertation is to improve our understanding of this complex chemistry by investigating the rate-limiting elementary reactions which are part of the OH-initiated oxidation of important VOCs. Experimental (discharge flow technique coupled with resonance fluorescence and laser induced fluorescence) and theoretical studies (Density Functional Theory computations) of the kinetics of three atmospheric VOCs, acetic acid, 1,3-butadiene and methyl ethyl ketone are discussed. The acetic acid and OH reaction has been thought to undergo a hydrogen-bonded complex mediated pathway instead of a direct one leading to faster rate constants at lower temperature. Our results for the experimental investigation between 263-373 K and pressures of 2-5 Torr for the gas phase reaction of acetic acid with OH confirm the complex mediated reaction mechanism and indicate that acetic acid can play an important role especially in the oxidative chemistry of upper troposphere. The 1,3-butadiene and OH reaction is thought to undergo electrophilicaddition by OH which could display a complex pressure dependence similar to isoprene and 232-butenol as noted earlier in this laboratory. However, our results for the kinetics of the reaction between 273-423 K and a pressure range of 1

  17. Methyl chavicol: characterization of its biogenic emission rate, abundance, and oxidation products in the atmosphere

    Science.gov (United States)

    Bouvier-Brown, N. C.; Goldstein, A. H.; Worton, D. R.; Matross, D. M.; Gilman, J. B.; Kuster, W. C.; Welsh-Bon, D.; Warneke, C.; de Gouw, J. A.; Cahill, T. M.; Holzinger, R.

    2009-03-01

    We report measurements of ambient atmospheric mixing ratios for methyl chavicol and determine its biogenic emission rate. Methyl chavicol, a biogenic oxygenated aromatic compound, is abundant within and above Blodgett Forest, a ponderosa pine forest in the Sierra Nevada Mountains of California. Methyl chavicol was detected simultaneously by three in-situ instruments - a gas chromatograph with mass spectrometer detector (GC-MS), a proton transfer reaction mass spectrometer (PTR-MS), and a thermal desorption aerosol GC-MS (TAG) - and found to be abundant within and above Blodgett Forest. Methyl chavicol atmospheric mixing ratios are strongly correlated with 2-methyl-3-buten-2-ol (MBO), a light- and temperature-dependent biogenic emission from the ponderosa pine trees at Blodgett Forest. Scaling from this correlation, methyl chavicol emissions account for 4-68% of the carbon mass emitted as MBO in the daytime, depending on the season. From this relationship, we estimate a daytime basal emission rate of 0.72-10.2 μgCg-1 h-1, depending on needle age and seasonality. We also present the first observations of its oxidation products (4-methoxybenzaldehyde and 4-methyoxy benzene acetaldehyde) in the ambient atmosphere. Methyl chavicol is a major essential oil component of many plant species. This work suggests that methyl chavicol plays a significant role in the atmospheric chemistry of Blodgett Forest, and potentially other sites, and should be included explicitly in both biogenic volatile organic carbon emission and atmospheric chemistry models.

  18. Nitrogen oxide air pollution: atmospheric chemistry. 1964-1978 (citations from the NTIS data base). Report for 1964-78

    Energy Technology Data Exchange (ETDEWEB)

    Cavagnaro, D.M.

    1980-10-01

    Research reports on photochemical air pollution models, smog chemistry and reactivity, and SSt exhaust effects are cited in the bibliography. Auroral and upper atmospheric in chemistry, and photochemistry of naturally occurring nitrogen oxides are excluded. (Contains 247 citations)

  19. Oxidation of elemental mercury in the atmosphere; Constraints imposed by global scale modelling

    Energy Technology Data Exchange (ETDEWEB)

    Bergan, Torbjoern; Rodhe, Henning [Stockholm Univ. (Sweden). Dept. of Meteorology

    2000-05-01

    Based on the global mercury model published by Bergan et al. (1999), we present here further results from simulations where the central theme has been to evaluate the role of ozone and the hydroxyl radical as possible gas phase oxidants for the oxidation of elemental mercury in the atmosphere. The magnitude of natural and man-made mercury emissions are taken from recent literature estimates and the flux from land areas is assumed to vary by season. We consider only two mercury reservoirs, elemental mercury, Hg{sup 0}, and the more soluble divalent form, Hgll. Wet and dry deposition of Hgll is explicitly treated. Applying monthly mean fields of ozone for the oxidation of gas phase Hg{sup 0} and using the reaction rate by Hall (1995) yields a global transformation of Hg{sup 0} to Hgll which is too slow to keep the simulated concentration of Hg{sup 0} near observed values. This shows that there are additional important removal processes for Hg{sup 0} or that the reaction rate proposed by Hall (1995) is too slow. A simulation in which the oxidation rate was artificially increased, so that the global turn-over time of Hg{sup 0} was one year and the simulated average concentration of Hg{sup 0} was realistic, produced latitudinal and seasonal variations in Hg{sup 0} that did not support the hypothesis that gas phase reaction with O{sub 3} is the major oxidation process for Hg{sup 0}. Recent studies indicate that OH may be an important gas phase oxidant for Hg{sup 0}. Using OH as the oxidant and applying the preliminary oxidation rate by Sommar et al. (1999) gave an unrealistically large removal of Hg{sup 0} from the atmosphere. From calculations using a slower reaction rate, corresponding to a turn-over time of Hg{sup 0} of one year, we calculated concentrations of both Hg{sup 0} in surface air and Hgll in precipitation which correspond, both in magnitude and temporal variation, to seasonal observations in Europe and North America. This result supports the suggestion that

  20. Heterogeneous Oxidation of Atmospheric Organic Aerosol: Kinetics of Changes to the Amount and Oxidation State of Particle-Phase Organic Carbon.

    Science.gov (United States)

    Kroll, Jesse H; Lim, Christopher Y; Kessler, Sean H; Wilson, Kevin R

    2015-11-01

    Atmospheric oxidation reactions are known to affect the chemical composition of organic aerosol (OA) particles over timescales of several days, but the details of such oxidative aging reactions are poorly understood. In this study we examine the rates and products of a key class of aging reaction, the heterogeneous oxidation of particle-phase organic species by the gas-phase hydroxyl radical (OH). We compile and reanalyze a number of previous studies from our laboratories involving the oxidation of single-component organic particles. All kinetic and product data are described on a common basis, enabling a straightforward comparison among different chemical systems and experimental conditions. Oxidation chemistry is described in terms of changes to key ensemble properties of the OA, rather than to its detailed molecular composition, focusing on two quantities in particular, the amount and the oxidation state of the particle-phase carbon. Heterogeneous oxidation increases the oxidation state of particulate carbon, with the rate of increase determined by the detailed chemical mechanism. At the same time, the amount of particle-phase carbon decreases with oxidation, due to fragmentation (C-C scission) reactions that form small, volatile products that escape to the gas phase. In contrast to the oxidation state increase, the rate of carbon loss is nearly uniform among most systems studied. Extrapolation of these results to atmospheric conditions indicates that heterogeneous oxidation can have a substantial effect on the amount and composition of atmospheric OA over timescales of several days, a prediction that is broadly in line with available measurements of OA evolution over such long timescales. In particular, 3-13% of particle-phase carbon is lost to the gas phase after one week of heterogeneous oxidation. Our results indicate that oxidative aging represents an important sink for particulate organic carbon, and more generally that fragmentation reactions play a major

  1. Oxidation of a new Biogenic VOC: Chamber Studies of the Atmospheric Chemistry of Methyl Chavicol

    Science.gov (United States)

    Bloss, William; Alam, Mohammed; Adbul Raheem, Modinah; Rickard, Andrew; Hamilton, Jacqui; Pereira, Kelly; Camredon, Marie; Munoz, Amalia; Vazquez, Monica; Vera, Teresa; Rodenas, Mila

    2013-04-01

    The oxidation of volatile organic compounds (VOCs) leads to formation of ozone and SOA, with consequences for air quality, health, crop yields, atmospheric chemistry and radiative transfer. Recent observations have identified Methyl Chavicol ("MC": Estragole; 1-allyl-4-methoxybenzene, C10H12O) as a major BVOC above pine forests in the USA, and oil palm plantations in Malaysian Borneo. Palm oil cultivation, and hence MC emissions, may be expected to increase with societal food and bio fuel demand. We present the results of a series of simulation chamber experiments to assess the atmospheric fate of MC. Experiments were performed in the EUPHORE facility, monitoring stable product species, radical intermediates, and aerosol production and composition. We determine rate constants for reaction of MC with OH and O3, and ozonolysis radical yields. Stable product measurements (FTIR, PTRMS, GC-SPME) are used to determine the yields of stable products formed from OH- and O3- initiated oxidation, and to develop an understanding of the initial stages of the MC degradation chemistry. A surrogate mechanism approach is used to simulate MC degradation within the MCM, evaluated in terms of ozone production measured in the chamber experiments, and applied to quantify the role of MC in the real atmosphere.

  2. Transparent conductive indium-doped zinc oxide films prepared by atmospheric pressure plasma jet

    Energy Technology Data Exchange (ETDEWEB)

    Chang, Kow-Ming [Department of Electronics Engineering and Institute of Electronics, National Chiao Tung University, 1001 Ta Hsueh Road, Hsinchu, Taiwan 30010 (China); College of Electrical and Information Engineering, I-Shou University, Kaohsiung County, Taiwan 84001 (China); Huang, Sung-Hung, E-mail: sunghunghuang@gmail.com [Department of Electronics Engineering and Institute of Electronics, National Chiao Tung University, 1001 Ta Hsueh Road, Hsinchu, Taiwan 30010 (China); Wu, Chin-Jyi [Industrial Technology Research Institute, Mechanical and Systems Research Laboratories, 195, Sec. 4, Chung Hsing Rd., Chutung, Hsinchu, 31040, Taiwan (China); Lin, Wei-Li; Chen, Wei-Chiang; Chi, Chia-Wei [Department of Electronics Engineering and Institute of Electronics, National Chiao Tung University, 1001 Ta Hsueh Road, Hsinchu, Taiwan 30010 (China); Lin, Je-Wei; Chang, Chia-Chiang [Industrial Technology Research Institute, Mechanical and Systems Research Laboratories, 195, Sec. 4, Chung Hsing Rd., Chutung, Hsinchu, 31040, Taiwan (China)

    2011-05-31

    Atmospheric-pressure plasma processing has attracted much interest for industrial applications due to its low cost, high processing speed and simple system. In this study, atmospheric-pressure plasma jet technique was developed to deposit indium-doped zinc oxide films. The inorganic metal salts of zinc nitrate and indium nitrate were used as precursors for Zn ions and In ions, respectively. The effect of different indium doping concentration on the morphological, structural, electrical and optical properties of the films was investigated. Grazing incidence X-ray diffraction results show that the deposited films with a preferred (002) orientation. The lowest resistivity of 1.8 x 10{sup -3} {Omega} cm was achieved with the 8 at.% indium-doped solution at the substrate temperature of 200 deg. C in open air, and average transmittance in the visible region was more than 80%.

  3. Glass-ceramic sealant for solid oxide fuel cells application: Characterization and performance in dual atmosphere

    Science.gov (United States)

    Sabato, A. G.; Cempura, G.; Montinaro, D.; Chrysanthou, A.; Salvo, M.; Bernardo, E.; Secco, M.; Smeacetto, F.

    2016-10-01

    A glass-ceramic composition was designed and tested for use as a sealant in solid oxide fuel cell (SOFC) planar stack design. The crystallization behaviour was investigated by calculating the Avrami parameter (n) and the activation energy for crystallization (Ec) was obtained. The calculated values for n and Ec were 3 and 413.5 kJ/mol respectively. The results of thermal analyses indicate that this composition shows no overlap between the sintering and crystallization stages and thus an almost pore-free sealant can be deposited and sintered at 850 °C in air for 30 min. A gas tightness test has been carried out at 800 °C for 1100 h in dual atmosphere (Ar-H2 and air) without recording any leakage. Morphological and crystalline phase analyses were conducted prior and following tests in dual atmospheres in order to assess the compatibility of the proposed sealant with the metallic interconnect.

  4. Oxygen dynamics in the aftermath of the Great Oxidation of Earth’s atmosphere

    DEFF Research Database (Denmark)

    Canfield, Donald Eugene; Ngombi-Pemba, Lauriss; Hammarlund, Emma;

    2013-01-01

    The oxygen content of Earth’s atmosphere has varied greatly through time, progressing from exceptionally low levels before about 2.3 billion years ago, to much higher levels afterward. In the absence of better information, we usually view the progress in Earth’s oxygenation as a series of steps......-oxygenated deep waters whereas the youngest were deposited in euxinic waters, which were globally extensive. These fluctuations in oxygenation were likely driven by the comings and goings of the Lomagundi carbon isotope excursion, the longest–lived positive δ13C excursion in Earth history, generating a huge...... oxygen source to the atmosphere. As the Lomagundi event waned, the oxygen source became a net oxygen sink as Lomagundi organic matter became oxidized, driving oxygen to low levels; this state may have persisted for 200 million years....

  5. Enhancement of atmospheric H2SO4/H2O nucleation: organic oxidation products versus amines

    Directory of Open Access Journals (Sweden)

    T. Berndt

    2013-06-01

    Full Text Available Atmospheric H2SO4/H2O nucleation influencing effects have been studied in the flow tube IfT-LFT (Institute for Tropospheric Research – Laminar Flow Tube at 293 ± 0.5 K and a pressure of 1 bar using synthetic air as the carrier gas. The presence of a possible background amine concentration in the order of 107–108 molecule cm−3 throughout the experiments has to be taken into account. In a first set of investigations, ozonolysis of olefins (tetramethylethylene, 1-methyl-cyclohexene, α-pinene and limonene for close to atmospheric concentrations, served as the source of OH radicals and possibly other oxidants initiating H2SO4 formation starting from SO2. The oxidant generation is inevitably associated with the formation of a series of organic oxidation products arising from the parent olefins. These products (first generation mainly showed no clear effect on the number of nucleated particles within a wide range of experimental conditions for H2SO4 concentrations higher than ~107 molecule cm−3. A comparison of the results of two different particle counters (50% cut-off size: about 1.5 nm or 2.5–3 nm suggested that the early growth process of the nucleated particles was not significantly influenced by the organic oxidation products. An additional, H2SO4-independent process of particle (nano-CN formation was observed in the case of α-pinene and limonene ozonolysis for H2SO4 concentrations smaller than ~10 7 molecule cm−3. Furthermore, the findings confirm the existence of an additional oxidant for SO2 beside OH radicals, very likely stabilized Criegee Intermediate (sCI. In the case of the ozonolysis of tetramethylethylene, the H2SO4 measurements in the absence and presence of an OH radical scavenger were well described by modelling using recently obtained kinetic data for the sCI reactivity in this system. A second set of experiments has been performed in the presence of added amines (trimethylamine, dimethylamine, aniline and pyridine in

  6. OH regeneration from methacrolein oxidation investigated in the atmosphere simulation chamber SAPHIR

    Directory of Open Access Journals (Sweden)

    H. Fuchs

    2014-02-01

    Full Text Available Hydroxyl radicals (OH are the most important reagent for the oxidation of trace gases in the atmosphere. OH concentrations measured during recent field campaigns in isoprene rich environments were unexpectedly large. A number of studies showed that unimolecular reactions of organic peroxy radicals (RO2 formed in the initial reaction step of isoprene with OH play an important role for the OH budget in the atmosphere at low mixing ratios of nitrogen monoxide (NO of less than 100 pptv. It has also been suggested that similar reactions potentially play an important role for RO2 from other compounds. Here, we investigate the oxidation of methacrolein (MACR, one major oxidation product of isoprene, by OH in experiments in the simulation chamber SAPHIR under controlled atmospheric conditions. The experiments show that measured OH concentrations are approximately 50% larger than calculated by current chemical models for conditions of the experiments (NO mixing ratio of 90 pptv. The analysis of the OH budget reveals a so far unaccounted OH source, which is correlated with the production rate of RO2 radicals from MACR. In order to balance the measured OH destruction rate, (0.77±0.3 OH radicals need to be additionally reformed from each OH that has reacted with MACR. The strong correlation of the missing OH source with the production of RO2 radicals is consistent with the concept of OH formation from unimolecular isomerization and decomposition reactions of RO2. The comparison of observations with model calculations gives a lower limit of 0.03 s−1 for the reaction rate constant, if the OH source is attributed to an isomerization reaction of one RO2 species formed in the MACR+OH reaction as suggested in literature. This fast isomerization reaction would be competitive to the reaction of this RO2 species with minimum 150 pptv NO.

  7. Synthesis of barium titanium oxide from barium sulphate and anatase. Study of equimolar mixtures under different atmospheres

    International Nuclear Information System (INIS)

    To enable the ceramization of a barium sulphate-rich radioactive waste the synthesis of barium titanium oxide is studied by using anatase and barium sulphate. As a function of the calcination atmosphere, helium (or air) and Ar/H2, two reactions are studied. A mechanism of barium titanium oxide synthesis in helium (or in air) is proposed

  8. Complexes and Clusters of Water Relevant to Atmospheric Chemistry: H2O Complexes with Oxidants

    OpenAIRE

    Sennikov, Peter; Ignatov, Stanislav; Schrems, Otto

    2005-01-01

    Experimental observations and data from quantum chemical calculations related to the complexes between water molecules and small oxygen containing inorganic species which are playing an important role as oxidants (O(1D), O(3P), O2(X3Σg), O2(b1Σg+), O3, HO, HOO, HOOO, and H2O2) in the atmosphere are reviewed with emphasis on their structure, hydrogen bonding, interaction energies, thermodynamic parameters and IR spectra. In recent years, weakly bound complexes containing water have i...

  9. 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......, temperature, pressure and CO/O2 ratio. The frequency of the oscillations is very well defined and increases over time. The oscillation frequency is furthermore strongly temperature dependent with increasing temperature resulting in increasing frequency. A plausible mechanism for the oscillations is proposed...

  10. Ozone oxidation of antidepressants in wastewater –Treatment evaluation and characterization of new by-products by LC-QToFMS

    OpenAIRE

    Lajeunesse André; Blais Mireille; Barbeau Benoît; Sauvé Sébastien; Gagnon Christian

    2013-01-01

    Abstract Background The fate of 14 antidepressants along with their respective N-desmethyl metabolites and the anticonvulsive drug carbamazepine was examined in a primary sewage treatment plant (STP) and following advanced treatments with ozone (O3). The concentrations of each pharmaceutical compound were determined in raw sewage, effluent and sewage sludge samples by LC-MS/MS analysis. The occurrence of antidepressant by-products formed in treated effluent after ozonation was also investigat...

  11. Heterogeneous chemistry and reaction dynamics of the atmospheric oxidants, O3, NO3, and OH, on organic surfaces.

    Science.gov (United States)

    Chapleski, Robert C; Zhang, Yafen; Troya, Diego; Morris, John R

    2016-07-01

    Heterogeneous chemistry of the most important atmospheric oxidants, O3, NO3, and OH, plays a central role in regulating atmospheric gas concentrations, processing aerosols, and aging materials. Recent experimental and computational studies have begun to reveal the detailed reaction mechanisms and kinetics for gas-phase O3, NO3, and OH when they impinge on organic surfaces. Through new research approaches that merge the fields of traditional surface science with atmospheric chemistry, researchers are developing an understanding for how surface structure and functionality affect interfacial chemistry with this class of highly oxidizing pollutants. Together with future research initiatives, these studies will provide a more complete description of atmospheric chemistry and help others more accurately predict the properties of aerosols, the environmental impact of interfacial oxidation, and the concentrations of tropospheric gases.

  12. Atmospheric Oxidation of Squalene: Molecular Study Using COBRA Modeling and High-Resolution Mass Spectrometry

    Energy Technology Data Exchange (ETDEWEB)

    Fooshee, David R.; Aiona, Paige K.; Laskin, Alexander; Laskin, Julia; Nizkorodov, Sergey; Baldi, Pierre

    2015-10-22

    Squalene is a major component of skin and plant surface lipids, and is known to be present at high concentrations in indoor dust. Its high reactivity toward ozone makes it an important ozone sink and a natural protectant against atmospheric oxidizing agents. While the volatile products of squalene ozonolysis are known, the condensed-phase products have not been characterized. We present an analysis of condensed-phase products resulting from an extensive oxidation of squalene by ozone probed by electrospray ionization (ESI) high-resolution mass spectrometry (HR-MS). A complex distribution of nearly 1,300 peaks assignable to molecular formulas is observed in direct infusion positive ion mode ESI mass spectra. The distribution of peaks in the mass spectra suggests that there are extensive cross-coupling reactions between hydroxy-carbonyl products of squalene ozonolysis. To get additional insights into the mechanism, we apply a Computational Brewing Application (COBRA) to simulate the oxidation of squalene in the presence of ozone, and compare predicted results with those observed by the HR-MS experiments. The system predicts over one billion molecular structures between 0-1450 Da, which correspond to about 27,000 distinct elemental formulas. Over 83% of the squalene oxidation products inferred from the mass spectrometry data are matched by the simulation. Simulation indicates a prevalence of peroxy groups, with hydroxyl and ether groups being the second-most important O-containing functional groups formed during squalene oxidation. These highly oxidized products of squalene ozonolysis may accumulate on indoor dust and surfaces, and contribute to their redox capacity.

  13. CO oxidation over ruthenium: identification of the catalytically active phases at near-atmospheric pressures

    Energy Technology Data Exchange (ETDEWEB)

    Gao, Feng; Goodman, Wayne D.

    2012-05-21

    CO oxidation was carried out over Ru(0001) and RuO2(110) thin film grown on Ru(0001) at various O2/CO ratios near atmospheric pressures. Reaction kinetics, coupled with in situ polarization modulation infrared reflection absorption spectroscopy (PM-IRAS) and post-reaction Auger electron spectroscopy (AES) measurements were used to identify the catalytically relevant phases at different reaction conditions. Under stoichiometric and reducing conditions at all reaction temperatures, as well as net-oxidizing reaction conditions below {approx}475 K, a reduced metallic phase with chemisorbed oxygen is the thermodynamically stable and catalytically active phase. On this surface CO oxidation occurs at surface defect sites, for example step edges. Only at net-oxidizing reaction conditions and above {approx}475 K is the RuO2 thin film grown on metallic Ru stable and active. However, RuO2 is not active itself without the existence of the metal substrate, suggesting the importance of a strong metal-substrate interaction (SMSI).

  14. Synthesis of porous superparamagnetic iron oxides from colloidal nanoparticles: Effect of calcination temperature and atmosphere

    Energy Technology Data Exchange (ETDEWEB)

    Cheng, Wei; Xu, Jing; Ding, Wei; Wang, Yajie; Zheng, Wenping; Wu, Feng; Li, Jinjun, E-mail: ljjcbacademy@163.com

    2015-03-01

    Nanostructured iron oxides with superparamagnetism were synthesized from colloidal particles of hydrous iron oxide. The synthesis procedure involved preparation of acetone-nanoparticle composite and calcination of the composite in air or nitrogen. The effects of calcination temperature and atmosphere on the properties of the products were investigated. Powder X-ray diffraction, {sup 57}Fe Mössbauer spectra, transmission electron microscopy, nitrogen sorption, thermal analysis and vibrating-sample magnetometry were applied to characterize the materials. The products calcined in flowing air are composed of nanoparticles, while those calcined in flowing nitrogen contain nanosheets. The former has larger specific surface areas, whereas the latter has stronger saturation magnetization in external magnetic field. Increasing calcination temperature reduced the specific surface area of the product, whereas enhanced its saturation magnetization. Furthermore, the iron oxides with superparamagnetism showed good affinity to arsenite, and therefore they could be potential adsorbents for arsenic remediation in water. - Highlights: • Nanostructured superparamagnetic iron oxides were synthesized from colloidal nanoparticles. • Calcination in air led to formation of nanoparticles. • Calcination in nitrogen led to formation of nanosheets. • The superparamagnetic materials had high adsorption capabilities for arsenite.

  15. Methyl chavicol: characterization of its biogenic emission rate, abundance, and oxidation products in the atmosphere

    Directory of Open Access Journals (Sweden)

    N. C. Bouvier-Brown

    2008-11-01

    Full Text Available We report measurements of ambient atmospheric mixing ratios for methyl chavicol and determine its biogenic emission rate. Methyl chavicol, a biogenic oxygenated aromatic compound, is abundant within and above Blodgett Forest, a ponderosa pine forest in the Sierra Nevada Mountains of California. Methyl chavicol was detected simultaneously by three in-situ instruments – a gas chromatograph with mass spectrometer detector (GC-MS, a proton transfer reaction mass spectrometer (PTR-MS, and a thermal desorption aerosol GC-MS (TAG – and found to be abundant within and above Blodgett Forest, a ponderosa pine forest in the Sierra Nevada Mountains of California. Methyl chavicol atmospheric mixing ratios are strongly correlated with 2-methyl-3-buten-2-ol (MBO, a light- and temperature-dependent biogenic emission from the ponderosa pine trees at Blodgett Forest. Scaling from this correlation, methyl chavicol emissions account for 4–68% of the carbon mass emitted as MBO in the daytime, depending on the season. From this relationship, we estimate a daytime basal emission rate of 0.72–10.2 μgCg−1h−1, depending on needle age and seasonality. We also present the first observations of its oxidation products (4-methoxybenzaldehyde and 4-methyoxy benzene acetaldehyde in the ambient atmosphere. Methyl chavicol is a major essential oil component of many plant species. This work suggests that methyl chavicol plays a significant role in the atmospheric chemistry of Blodgett Forest, and potentially other sites, and should be included explicitly in both biogenic volatile organic carbon emission and atmospheric chemistry models.

  16. Magnetic Properties of Iron Oxide Minerals in Atmospheric Dust and Source Sediments from Western US

    Science.gov (United States)

    Moskowitz, B. M.; Yauk, K.; Till, J. L.; Berquo, T. S.; Banerjee, S. K.; Reynolds, R. L.; Goldstein, H. L.

    2011-12-01

    Atmospheric dust contains iron oxide minerals that can play important roles in various physical and biological processes affecting atmospheric and surface temperatures, marine phytoplankton productivity, and human health. Iron oxide minerals in dust deposited on mountain snow cover are especially important because these minerals absorb solar and IR radiation leading to changes in albedo and affecting the timing and rate of spring and summer snowpack melting. As part of an ongoing project to study physical and chemical properties of dust from sources to sinks in the western US, we will describe one approach to characterize iron oxide mineralogy using magnetic property measurements and Mossbauer spectroscopy. Magnetic property measurements over a wide range of temperatures (2-300 K) and magnetic fields (0-5 T) are particularly sensitive to composition, particle size (from nanometer to micrometer), and concentration of iron oxide and oxyhydroxide minerals. The high sensitivity of magnetic measurements to target minerals allows the measurement of bulk samples preventing any aliasing of composition or grain size resulting from attempts at prior magnetic separation. In addition, different magnetic measurement protocols can isolate different particle-size assemblages and different compositions in multicomponent mixtures and help to identify dust-source areas. These techniques have been applied to dust deposited on snow (DOS) cover of the San Juan Mountains, Colorado (collected 2005-2010) and Wasatch Mountains, Utah (collected 2010) and possible dust-source sediments from the North American Great Basin and Colorado Plateau deserts. Results show that all samples contain a high coercivity phase consistent with hematite and/or goethite as the dominate ferric oxide mineral plus minor amounts of magnetite (hematite concentration ( x2 difference) but with similar spreads in magnetite concentrations (0.05-0.2%) within each group. Preliminary Mössbauer spectroscopy at 300 K for

  17. Photon and Water Mediated Sulfur Oxide and Acid Chemistry in the Atmosphere of Venus

    Science.gov (United States)

    Kroll, Jay A.; Vaida, Veronica

    2014-06-01

    Sulfur compounds have been observed in the atmospheres of a number of planetary bodies in our solar system including Venus, Earth, Mars, Io, Europa, and Callisto. The global cloud cover on Venus located at an altitude between 50 and 80 kilometers is composed primarily of sulfuric acid (H_2SO_4) and water. Planetary photochemical models have attempted to explain observations of sulfuric acid and sulfur oxides with significant discrepancies remaining between models and observation. In particular, high SO_2 mixing ratios are observed above 90 km which exceed model predictions by orders of magnitude. Work recently done in the Vaida lab has shown red light can drive photochemistry through overtone pumping for acids like H_2SO_4 and has been successful in explaining much of the sulfur chemistry in Earth's atmosphere. Water can have a number of interesting effects such as catalysis, suppression, and anti-catalysis of thermal and photochemical processes. We investigate the role of water complexes in the hydration of sulfur oxides and dehydration of sulfur acids and present spectroscopic studies to document such effects. We investigate these reactions using FTIR and UV/Vis spectroscopy and will report on our findings.

  18. Carbon isotope excursions and the oxidant budget of the Ediacaran atmosphere and ocean

    Science.gov (United States)

    Bristow, Thomas F.; Kennedy, Martin J.

    2008-11-01

    A possible global drop in marine carbon isotope values to aslow as -12 Peedee belemnite (PDB), recorded in the EdiacaranShuram Formation of Oman, has been attributed to the non-steady-stateoxidation of oceanic dissolved organic carbon (DOC) resultingfrom the rise in atmospheric oxygen to near modern values atthe end of the Precambrian. Geologic constraints indicate thatthe excursion lasted between 25 and 50 m.y., requiring a DOCpool thousands of times to 10,000 times the modern inventoryto conform with carbon isotope mass balance calculations fora -12 excursion. At the consequent rates of DOC oxidation,oceanic sulfate and oxygen in the atmosphere and oceans areexhausted on a time scale of 800 k.y. Oxidant depletion isincompatible with independent geochemical and biological indicatorsthat show oceanic sulfate and oxygen levels were maintainedor increased during the Shuram excursion. Furthermore, a DOC-drivenexcursion does not explain strong covariation between the carbonand oxygen isotope record. These indicators show that negativeisotope excursions recorded in the Shuram and other Ediacaransections are unlikely to represent a global ocean signal.

  19. Process-Scale Modeling of Atmosphere-Snowpack Exchange of Nitrogen Oxides

    Science.gov (United States)

    Murray, K. A.; Doskey, P. V.; Ganzeveld, L.

    2013-12-01

    Snowpack over glacial ice is a reservoir for reactive nitrogen gases. Previous studies indicate nitrogen oxides (NOx) are generated in snowpack interstitial air through photolysis of nitrate (NO3-). Gradients in NOx mixing ratios between snowpack interstitial air and the overlying atmosphere regulate exchange of NOx with snowpack, which affects the Arctic ozone budget and climate. To better understand the dynamics of cryosphere-atmosphere exchange of NOx in the Arctic, we collected 2 years of meteorological and chemical data in and above the snowpack at Summit, Greenland. The comprehensive dataset indicates NOx emissions are episodic, with NOx enhancements in snowpack in early spring during high wind speed events (10-20 mph), which elevate NOx levels to ~500 pptv at depths of 2.5 m. Analysis of the observations will be based upon application of a 1-D process-scale model of atmosphere-snowpack exchange of NOx. The model will include representations of the snowpack chemistry in gas and aqueous phases, mass transfer of chemical species between phases, and physical transport by diffusion and wind pumping. The model will calculate the chemical and physical tendencies in three dimensions: depth, time, and intensity. Analysis of the tendencies will allow us to perform model sensitivity tests of pertinent snowpack physical and chemical processes. The end-goal of the project is to simplify the major tendencies into a parameterized model add-on for use in global models to determine the importance of properly representing snowpack in global model simulations.

  20. Emission to atmosphere of tritiated water formed at soil surface by oxidation of HT

    International Nuclear Information System (INIS)

    In the event of a release of molecular tritium to atmosphere, some tritium can oxidized at soil surface and be gradually re-emitted to atmosphere as HTO. The two processes are characterized by a deposition velocity and an emission rate, which are commonly used in deposition/emission models designed to calculate the concentrations of HTO in atmosphere. A technique has been developed to determine the emission rate and its evolution, by covering a small area of undisturbed soil by a field chamber, exposing the enclosed soil to molecular tritium, then determining the changes in HTO vapour content of a measured air-stream passing through the chamber. The emission rate is derived by dividing the amount of HTO extracted from the chamber during a given period of time, by the average amount of HTO contained in the soil during the same period. First experiments have been done on bare and grass-covered soils. The data obtained from these small-scale field experiments are consistent with those obtained from a full-scale field study carried out at nearly the same place

  1. Electrochemical capacitance of iron oxide nanotube (Fe-NT): effect of annealing atmospheres

    Science.gov (United States)

    Sarma, Biplab; Jurovitzki, Abraham L.; Ray, Rupashree S.; Smith, York R.; Mohanty, Swomitra K.; Misra, Mano

    2015-07-01

    The effect of annealing atmosphere on the supercapacitance behavior of iron oxide nanotube (Fe-NT) electrodes has been explored and reported here. Iron oxide nanotubes were synthesized on a pure iron substrate through an electrochemical anodization process in an ethylene glycol solution containing 3% H2O and 0.5 wt.% NH4F. Subsequently, the annealing of the nanotubes was carried out at 500 °C for 2 h in various gas atmospheres such as air, oxygen (O2), nitrogen (N2), and argon (Ar). The morphology and crystal phases evolved after the annealing processes were examined via field emission scanning electron microscopy, x-ray diffraction, Raman spectroscopy, and x-ray photoelectron spectroscopy. The electrochemical capacitance properties of the annealed Fe-NT electrodes were evaluated by conducting cyclic voltammetry (CV), galvanostatic charge-discharge, and electrochemical impedance spectroscopy tests in the Li2SO4 electrolyte. Based on these experiments, it was found that the capacitance of the Fe-NT electrodes annealed in air and O2 atmospheres shows mixed behavior comprising both the electric double layer and pseudocapacitance. However, annealing in N2 and Ar environments resulted in well-defined redox peaks in the CV profiles of the Fe-NT electrodes, which are therefore attributed to the relatively higher pseudonature of the capacitance in these electrodes. Based on the galvanostatic charge-discharge studies, the specific capacitance achieved in the Fe-NT electrode after annealing in Ar was about 300 mF cm-2, which was about twice the value obtained for N2-annealed Fe-NTs and three times higher than those annealed in air and O2. The experiments also demonstrated excellent cycle stability for the Fe-NT electrodes with 83%-85% capacitance retention, even after many charge-discharge cycles, irrespective of the gas atmospheres used during annealing. The increase in the specific capacitance was discussed in terms of increased oxygen vacancies as a result of the

  2. Product characteristics from the torrefaction of oil palm fiber pellets in inert and oxidative atmospheres.

    Science.gov (United States)

    Chen, Wei-Hsin; Zhuang, Yi-Qing; Liu, Shih-Hsien; Juang, Tarng-Tzuen; Tsai, Chi-Ming

    2016-01-01

    The aim of this work was to study the characteristics of solid and liquid products from the torrefaction of oil palm fiber pellets (OPFP) in inert and oxidative environments. The torrefaction temperature and O2 concentration in the carrier gas were in the ranges of 275-350°C and 0-10 vol%, respectively, while the torrefaction duration was 30 min. The oxidative torrefaction of OPFP at 275°C drastically intensified the HHV of the biomass when compared to the non-oxidative torrefaction. OPFP torrefied at 300°C is recommended to upgrade the biomass, irrespective of the atmosphere. The HHV of condensed liquid was between 10.1 and 13.2 MJ kg(-)(1), and was promoted to 23.2-28.7 MJ kg(-)(1) following dewatering. This accounts for 92-139% improvement in the calorific value of the liquid. This reveals that the recovery of condensed liquid with dewatering is able to enhance the energy efficiency of a torrefaction system.

  3. Product characteristics from the torrefaction of oil palm fiber pellets in inert and oxidative atmospheres.

    Science.gov (United States)

    Chen, Wei-Hsin; Zhuang, Yi-Qing; Liu, Shih-Hsien; Juang, Tarng-Tzuen; Tsai, Chi-Ming

    2016-01-01

    The aim of this work was to study the characteristics of solid and liquid products from the torrefaction of oil palm fiber pellets (OPFP) in inert and oxidative environments. The torrefaction temperature and O2 concentration in the carrier gas were in the ranges of 275-350°C and 0-10 vol%, respectively, while the torrefaction duration was 30 min. The oxidative torrefaction of OPFP at 275°C drastically intensified the HHV of the biomass when compared to the non-oxidative torrefaction. OPFP torrefied at 300°C is recommended to upgrade the biomass, irrespective of the atmosphere. The HHV of condensed liquid was between 10.1 and 13.2 MJ kg(-)(1), and was promoted to 23.2-28.7 MJ kg(-)(1) following dewatering. This accounts for 92-139% improvement in the calorific value of the liquid. This reveals that the recovery of condensed liquid with dewatering is able to enhance the energy efficiency of a torrefaction system. PMID:26346262

  4. Thermoeconomic analysis of large solid oxide fuel cell plants: Atmospheric vs. pressurized performance

    International Nuclear Information System (INIS)

    A detailed thermoeconomic analysis of two large solid oxide fuel cell-based power plants operating at atmospheric pressure and 20 bar, respectively, is assessed in this work. The analyzed systems employ SOFC-GT (gas turbine) modules as main power generators; a bottom HRSC (heat recovery steam cycle) to generate additional electricity from the SOFC-GT exhaust hot gases is also included. The thermodynamic and economic performance of the two plant configurations are studied in detail: the exergy analysis shows an enhanced exergetic performance for the pressurized cycle that features components with higher efficiency and consequently a lower rate of exergy destruction (∼20% less than the atmospheric plant). The economic analysis considers the capital cost of each component within the system and is developed aiming at estimating the levelized cost of electricity. In order to match both exergetic and economic parts, a rigorous thermoeconomic analysis following the theory of Valero and Bejan [1,2] is implemented. A well-defined set of rules for the exergoeconomic balance around each plant component is specified and specific cost balance equations are thus derived. Results show how pressurized plant outperforms the atmospheric one, with a (on exergo-economic base) cost of electricity of 47.7 $/MWh instead of 64.2 $/MWh. Therefore, both exergetic and economic advantages result from the adoption of a pressurized SOFC-GT cycle in the framework of future advance power plants based on high-temperature fuel cells. - Highlights: • Exergy analysis of atmospheric and pressurized SOFC plants. • Exergy destruction in a fuel cell hybrid power plant. • Rigorous thermoeconomic methodology to assess the performance of different power generation plants. • Economic performance of SOFC plants

  5. Atmospheric nitrous oxide observations above the oceanic surface during the first Chinese Arctic Research Expedition

    Institute of Scientific and Technical Information of China (English)

    朱仁斌; 孙立广; 谢周清; 赵俊琳

    2003-01-01

    339 gas samples above oceanic surface were collected on the cruise of "Xuelong" expeditionary ship and nitrous oxide concentrations were analyzed in the laboratory. Results showed that Atmospheric average N20 concentration was 309 ± 3.8nL/L above the surface of northern Pacific and Arctic ocean. N2O concentrations were significantly different on the northbound and southbound track in the range of the same latitude, 308.0 ± 3.5 nL/L from Shanghai harbor to the Arctic and 311.9 ± 2.5 nL/L from the Arctic to Shanghai harbor. N2O concentration had a greater changing magnitude on the mid- and high-latitude oceanic surface of northern Pacific Ocean than in the other latitudinal ranges. The correlation between the concentrations of the compositions in the aerosol samples and atmospheric N2O showed that continental sources had a great contribution on atmospheric N2 O concentration above the oceanic surface. Atmospheric N2O concentration significantly increased when the expeditionary ship approached Shanghai harbor. The average N2O concentrations were 315.1 ±2.5 nL/L, 307.2 ±1.4 nL/L and 306.2 ±0.7 nL/L, respectively, at Shanghai harbor, at ice stations and at floating ices. The distribution of N2O concentrations was related with air pressure and temperature above the mid- and high-latitude Pacific Ocean.

  6. THE EFFECT OF OLIVE BY PRODUCTS AND THEIR EXTRACTS ON ANTIOXIDATIVE STATUS OF LAYING HENS AND OXIDATIVE STABILITY OF EGGS ENRICHED WITH N-3 FATTY ACIDS

    Directory of Open Access Journals (Sweden)

    Vida Rezar

    2015-09-01

    Full Text Available The aim of the study was to assess the effects olive leaves, pulp and their extract supplementation on performance, antioxidant status and oxidative stability of eggs. Oxidative stress was induced by the addition of 6% linseed oil in the feed. 94 individually caged laying hens, 40 weeks old, were included in the study. Animals were divided into 6 groups. The feed of each group was composed of a basic feed, supplemented with: group Cont - no supplement, Vit E - 150 IU of α-tocopherol acetate /kg, Olive L - 1% of olive leaves, Olive Ex - extract from olive leaves, the Pulp group - 1% of dried and ground pulp and Pulp Ex - extract from pulp. Based on the results we found out that supplementation of vitamin E, olive leaves, pulp and their extracts had no effect on the performance of hens and showed neither a lymphocyte DNA damage preventive activity nor influence malondialdehyde (MDA concentration in plasma. The results suggest that α-tocopherol acetate and olive leaves supplementation had significant effect on the MDA content of the stored eggs. Supplements, except vitamin E had neither influence on antioxidant activity (ACL in eggs nor on n-3 PUFA in fresh and 40 days stored eggs.

  7. Response of Atmospheric-Methane Oxidation to Methane-Flux Manipulation in a Laboratory Soil-Column Experiment

    Science.gov (United States)

    Schroth, M. H.; Mignola, I.; Henneberger, R.

    2015-12-01

    Upland soils are an important sink for atmospheric methane (CH4). Uptake of atmospheric CH4 in soils is generally diffusion limited, and is mediated by aerobic CH4 oxidizing bacteria (MOB) that possess a high-affinity form of a key enzyme, allowing CH4 consumption at near-atmospheric concentrations (≤ 1.9 µL/L). As cultivation attempts for these high-affinity MOB have shown little success, there remains much speculation regarding their functioning in different environments. For example, it is frequently assumed that they are highly sensitive to physical disturbance, but their response in activity and abundance to changes in substrate availability remains largely unknown. We present results of a laboratory column experiment conducted to investigate the response in activity and abundance of high-affinity MOB to an increase in CH4 flux. Intact soil cores, collected at a field site where atmospheric CH4 oxidation activity is frequently quantified, were transferred into two 1-m-long, 12-cm-dia. columns. The columns were operated at constant temperature in the dark, their headspace being continuously flushed with air. Diffusive gas-transport conditions were maintained in the reference column, whereas CH4 flux was increased in several steps in the treatment column by inducing advective gas flow using a diaphragm pump. Soil-gas samples periodically collected from ports installed along the length of the columns were analyzed for CH4 content. Together with measurements of soil-water content, atmospheric CH4 oxidation was quantified using the soil-profile method. First results indicate that atmospheric CH4 oxidation activity comparable with the field was maintained in the reference column throughout the experiment. Moreover, high-affinity MOB quickly adjusted to an increase in CH4 flux in the treatment column, efficiently consuming CH4. Quantification of MOB abundance is currently ongoing. Our data provide new insights into controls on atmospheric CH4 oxidation in soils.

  8. On-line coating of glass with tin oxide by atmospheric pressure chemical vapor deposition.

    Energy Technology Data Exchange (ETDEWEB)

    Allendorf, Mark D.; Sopko, J.F. (PPF Industries, Pittsburgh, PA); Houf, William G.; Chae, Yong Kee; McDaniel, Anthony H.; Li, M. (PPF Industries, Pittsburgh, PA); McCamy, J.W. (PPF Industries, Pittsburgh, PA)

    2006-11-01

    Atmospheric pressure chemical vapor deposition (APCVD) of tin oxide is a very important manufacturing technique used in the production of low-emissivity glass. It is also the primary method used to provide wear-resistant coatings on glass containers. The complexity of these systems, which involve chemical reactions in both the gas phase and on the deposition surface, as well as complex fluid dynamics, makes process optimization and design of new coating reactors a very difficult task. In 2001 the U.S. Dept. of Energy Industrial Technologies Program Glass Industry of the Future Team funded a project to address the need for more accurate data concerning the tin oxide APCVD process. This report presents a case study of on-line APCVD using organometallic precursors, which are the primary reactants used in industrial coating processes. Research staff at Sandia National Laboratories in Livermore, CA, and the PPG Industries Glass Technology Center in Pittsburgh, PA collaborated to produce this work. In this report, we describe a detailed investigation of the factors controlling the growth of tin oxide films. The report begins with a discussion of the basic elements of the deposition chemistry, including gas-phase thermochemistry of tin species and mechanisms of chemical reactions involved in the decomposition of tin precursors. These results provide the basis for experimental investigations in which tin oxide growth rates were measured as a function of all major process variables. The experiments focused on growth from monobutyltintrichloride (MBTC) since this is one of the two primary precursors used industrially. There are almost no reliable growth-rate data available for this precursor. Robust models describing the growth rate as a function of these variables are derived from modeling of these data. Finally, the results are used to conduct computational fluid dynamic simulations of both pilot- and full-scale coating reactors. As a result, general conclusions are

  9. Fractionation of sulfur isotopes during heterogeneous oxidation of SO2 in the atmosphere

    Science.gov (United States)

    Harris, E. J.; Sinha, B.; Hoppe, P.; Crowley, J.; Borrmann, S.; Foley, S. F.; Gnauk, T.; Van Pinxteren, D.; Herrmann, H.

    2011-12-01

    Sulfate and sulfur dioxide play an important role in environmental chemistry and climate, particularly through their effect on aerosols. Processing of aerosol through sulfate addition in clouds, which causes both hygroscopicity changes and mass increases, has been shown to modify the cloud condensation nucleus spectrum, leading to important climatological effects (Bower et al. 1997, Hegg et al. 2004). However, the uptake of sulfate and SO2 to aerosol in clouds is not well constrained, nor is it resolved for different particle types and sizes (Kasper-Giebl et al. 2000, Barrie et al. 2001). Measurements of stable sulfur isotopes can be used to investigate the chemistry of SO2 in the environment, providing insight into sources, sinks and oxidation pathways. Typical isotopic compositions for many sources have been measured, and the major current limitation is the lack of reliable fractionation factors - characteristic changes in isotopic composition caused by chemical reactions - with which to interpret the data. Laboratory values of fractionation factors for the major oxidation reactions have been measured in previous work, however there are no measurements or models to represent isotopic fractionation during heterogeneous oxidation on complex atmospheric surfaces. In this work the sulfur isotopic fractionation factors for SO2 oxidation have been measured on Sahara dust, obtained from the Cape Verde Islands, and sea salt aerosol, which was synthesised in the laboratory according to Millero (1974), modified to contain no sulfate. Sulfur dioxide with a known isotopic composition was oxidised on these surfaces under a variety of conditions including irradiation and ozonation, and the sulfur isotopic composition of the product sulfate was measured with the Cameca NanoSIMS 50. These laboratory results were then used to investigate the uptake of sulfur to particles in an orographic cloud during the HCCT campaign. The campaign took place at the Schmücke mountain in Germany

  10. Using Magnetism to Characterize and Distinguish High Coercivity Iron Oxide and Oxyhydroxide Minerals in Atmospheric Dust

    Science.gov (United States)

    Yauk, Kimberly E.

    Natural atmospheric dust samples collected from the American southwest and globally were measured using magnetic methods in order to separate remanence attributed to the high coercivity iron oxide and oxyhydroxide minerals hematite and goethite. Dust collected from mountain snow and dust source areas in nearby arid plains were analyzed using traditional room- and low temperature methods. Additional methods were created to better examine the weak, high coercivity components. Combinations of high fields (2.5-9 T), low temperatures (10-300 K), partial AF demagnetization, and thermal demagnetization to 400 K were implemented to separate each component. Percentages of remanence attributed to magnetite, hematite, and goethite were compared to results found by HIRM (hard isothermal remanent magnetization) and Mossbauer spectroscopy with good correlation and to coercivity unmixing methods without correlation. TRM (thermoremanent magnetization) was found to be an important step in magnetizing a greater portion of the goethite fraction. Further procedures for characterizing nano grain sizes would be illuminating.

  11. Coarsening of Pd nanoparticles in an oxidizing atmosphere studied by in situ TEM

    DEFF Research Database (Denmark)

    Simonsen, Søren Bredmose; Chorkendorff, Ib; Dahl, Søren;

    2016-01-01

    The coarsening of supported palladium nanoparticles in an oxidizing atmosphere was studied in situ by means of transmission electron microscopy (TEM). Specifically, the Pd nanoparticles were dispersed on a planar and amorphous Al2O3 support and were observed during the exposure to 10 mbar technical...... air at 650 °C. Time-resolved TEM image series reveal that the Pd nanoparticles were immobile and that a few percent of the nanoparticles grew or shrank, indicating a coarsening process mediated by the Ostwald ripening mechanism. The TEM image contrast suggests that the largest nanoparticles tended...... to wet the Al2O3 support to a higher degree than the smaller nanoparticles and that the distribution of projected particle sizes consequently broadens by the appearance of an asymmetric tail toward the larger particle sizes. A comparison with computer simulations based on a simple mean-field model...

  12. Nitric oxide delta band emission in the earth's atmosphere - Comparison of a measurement and a theory

    Science.gov (United States)

    Rusch, D. W.; Sharp, W. E.

    1981-01-01

    Attention is given to the altitude dependent emission rate in the delta-bands of nitric oxide as measured in the earth's atmosphere at night by a scanning ultraviolet spectrometer. It is noted that the reaction responsible is the two-body association of nitrogen and oxygen atoms. The measurements show a vertical intensity beneath the layer for the delta-band system of 19 R. The horizontal emission rate is found to increase from 70 R at 117 km to 140 R at 150 km. The data are analyzed with a one-dimensional, time-dependent, vertical-transport model of odd nitrogen photochemistry. The calculated and measured intensities agree so long as the quenching of N(2D) by atomic oxygen is near 5 x 10 to the -13 cu cm/sec.

  13. Mechanical characterisation of tungsten–1 wt.% yttrium oxide as a function of temperature and atmosphere

    Energy Technology Data Exchange (ETDEWEB)

    Palacios, T.; Jiménez, A. [Materials Science Department, Technical University of Madrid, E.T.S. de Ingenieros de Caminos, Canales y Puertos, C/Profesor Aranguren s/n, 28040 Madrid (Spain); Muñóz, A.; Monge, M.A.; Ballesteros, C. [Departamento de Física, Universidad Carlos III de Madrid, Leganés (Spain); Pastor, J.Y. [Materials Science Department, Technical University of Madrid, E.T.S. de Ingenieros de Caminos, Canales y Puertos, C/Profesor Aranguren s/n, 28040 Madrid (Spain)

    2014-11-15

    This study evaluates the mechanical behaviour of an Y{sub 2}O{sub 3}-dispersed tungsten (W) alloy and compares it to a pure W reference material. Both materials were processed via mechanical alloying (MA) and subsequent hot isostatic pressing (HIP). We performed non-standard three-point bending (TPB) tests in both an oxidising atmosphere and vacuum across a temperature range from 77 K, obtained via immersion in liquid nitrogen, to 1473 K to determine the mechanical strength, yield strength and fracture toughness. This research aims to evaluate how the mechanical behaviour of the alloy is affected by oxides formed within the material at high temperatures, primarily from 873 K, when the materials undergo a massive thermal degradation. The results indicate that the alloy is brittle to a high temperature (1473 K) under both atmospheres and that the mechanical properties degrade significantly above 873 K. We also used Vickers microhardness tests and the dynamic modulus by impulse excitation technique (IET) to determine the elastic modulus at room temperature. Moreover, we performed nanoindentation tests to determine the effect of size on the hardness and elastic modulus; however, no significant differences were found. Additionally, we calculated the relative density of the samples to assess the porosity of the alloy. Finally, we analysed the microstructure and fracture surfaces of the tested materials via field emission scanning electron microscopy (FE-SEM) and transmission electron microscopy (TEM). In this way, the relationship between the macroscopic mechanical properties and micromechanisms of failure could be determined based on the temperature and oxides formed.

  14. Oxygen dynamics in the aftermath of the Great Oxidation of Earth’s atmosphere

    Science.gov (United States)

    Canfield, Donald E.; Ngombi-Pemba, Lauriss; Hammarlund, Emma U.; Bengtson, Stefan; Chaussidon, Marc; Gauthier-Lafaye, François; Meunier, Alain; Riboulleau, Armelle; Rollion-Bard, Claire; Rouxel, Olivier; Asael, Dan; Pierson-Wickmann, Anne-Catherine; El Albani, Abderrazak

    2013-01-01

    The oxygen content of Earth’s atmosphere has varied greatly through time, progressing from exceptionally low levels before about 2.3 billion years ago, to much higher levels afterward. In the absence of better information, we usually view the progress in Earth’s oxygenation as a series of steps followed by periods of relative stasis. In contrast to this view, and as reported here, a dynamic evolution of Earth’s oxygenation is recorded in ancient sediments from the Republic of Gabon from between about 2,150 and 2,080 million years ago. The oldest sediments in this sequence were deposited in well-oxygenated deep waters whereas the youngest were deposited in euxinic waters, which were globally extensive. These fluctuations in oxygenation were likely driven by the comings and goings of the Lomagundi carbon isotope excursion, the longest–lived positive δ13C excursion in Earth history, generating a huge oxygen source to the atmosphere. As the Lomagundi event waned, the oxygen source became a net oxygen sink as Lomagundi organic matter became oxidized, driving oxygen to low levels; this state may have persisted for 200 million years. PMID:24082125

  15. Oxygen dynamics in the aftermath of the Great Oxidation of Earth's atmosphere.

    Science.gov (United States)

    Canfield, Donald E; Ngombi-Pemba, Lauriss; Hammarlund, Emma U; Bengtson, Stefan; Chaussidon, Marc; Gauthier-Lafaye, François; Meunier, Alain; Riboulleau, Armelle; Rollion-Bard, Claire; Rouxel, Olivier; Asael, Dan; Pierson-Wickmann, Anne-Catherine; El Albani, Abderrazak

    2013-10-15

    The oxygen content of Earth's atmosphere has varied greatly through time, progressing from exceptionally low levels before about 2.3 billion years ago, to much higher levels afterward. In the absence of better information, we usually view the progress in Earth's oxygenation as a series of steps followed by periods of relative stasis. In contrast to this view, and as reported here, a dynamic evolution of Earth's oxygenation is recorded in ancient sediments from the Republic of Gabon from between about 2,150 and 2,080 million years ago. The oldest sediments in this sequence were deposited in well-oxygenated deep waters whereas the youngest were deposited in euxinic waters, which were globally extensive. These fluctuations in oxygenation were likely driven by the comings and goings of the Lomagundi carbon isotope excursion, the longest-lived positive δ(13)C excursion in Earth history, generating a huge oxygen source to the atmosphere. As the Lomagundi event waned, the oxygen source became a net oxygen sink as Lomagundi organic matter became oxidized, driving oxygen to low levels; this state may have persisted for 200 million years.

  16. Atmospheric-pressure plasma-enhanced chemical vapor deposition of electrochromic organonickel oxide thin films with an atmospheric pressure plasma jet

    International Nuclear Information System (INIS)

    Deposition of electrochromic organonickel oxide (NiOxCy) films onto glass/indium tin oxide (ITO) substrates using atmospheric-pressure plasma-enhanced chemical vapor deposition with an atmospheric pressure plasma jet under various precursor injection angles is investigated. A precursor [nickelocene, Ni(C5H5)2] vapor, carried by argon gas and mixed with oxygen gas, is injected into an air plasma torch for the deposition of NiOxCy films by a short exposure of the substrate, 20 s, in the plasma. Uniform light modulation on glass/ITO/NiOxCy is produced while the moving glass/ITO substrate is exposed to the plasma torch at room temperature (∼ 23 °C) and under atmospheric pressure. Light modulation with up to a 40.9% transmittance variation at a wavelength of 513.9 nm under Li+ intercalation and de-intercalation in a 1 M LiClO4–propylene carbonate electrolyte is achieved. - Highlights: ► Rapid deposition of electrochromic NiOxCy film by atmospheric pressure plasma jet ► Uniform light modulation on NiOxCy film is produced. ► Nano-grains in NiOxCy films offer fast coloration and bleaching

  17. The impact of Southwest Airline's contribution to atmospheric Carbon Dioxide and Nitrous Oxide totals

    Science.gov (United States)

    Wilkerson, Cody L.

    Over the last century, aviation has grown to become an economical juggernaut. The industry creates innovation, connects people, and maintains a safety goal unlike any other field. However, as the world becomes more populated with technology and individuals, a general curiosity as to how human activity effects the planet is becoming of greater interest. This study presents what one domestic airline in the United States, Southwest Airlines, contributes to the atmospheric make-up of the planet. Utilizing various sources of quantifiable data, an outcome was reached that shows the amount of Carbon Dioxide and Nitrous Oxide produced by Southwest Airlines from 2002 to 2013. This topic was chosen due to the fact that there are no real quantifiable values of emission statistics from airlines available to the public. Further investigation allowed for Southwest Airlines to be compared to the overall Carbon Dioxide and Nitrous Oxide contributions of the United States for the year 2011. The results showed that with the absence of any set standard on emissions, it is vital that one should be established. The data showed that the current ICAO standard emission values showed a higher level of emissions than when Southwest Airline's fleet was analyzed using their actual fleet mix.

  18. Mainz Isoprene Mechanism 2 (MIM2: an isoprene oxidation mechanism for regional and global atmospheric modelling

    Directory of Open Access Journals (Sweden)

    D. Taraborrelli

    2008-07-01

    Full Text Available We present an oxidation mechanism of intermediate size for isoprene (2-methyl-1,3-butadiene suitable for simulations in regional and global atmospheric chemistry models, which we call MIM2. It is a reduction of the corresponding detailed mechanism in the Master Chemical Mechanism (MCM v3.1 and intended as the second version of the well-established Mainz Isoprene Mechanism (MIM. Our aim is to improve the representation of tropospheric chemistry in regional and global models under all NOx regimes. We evaluate MIM2 and re-evaluate MIM through comparisons with MCM v3.1. We find that MIM and MIM2 compute similar O3, OH and isoprene mixing ratios. Unlike MIM, MIM2 produces small relative biases for NOx and organic nitrogen-containing species due to a good representation of the alkyl and peroxy acyl nitrates (RONO2 and RC(OOONO2. Moreover, MIM2 computes only small relative biases with respect to hydrogen peroxide (H2O2, methyl peroxide (CH3OOH, methanol (CH3OH, formaldehyde (HCHO, peroxy acetyl nitrate (PAN, and formic and acetic acids (HCOOH and CH3C(OOH, being always below ≈6% in all NOx scenarios studied. Most of the isoprene oxidation products are represented explicitly, including methyl vinyl ketone (MVK, methacrolein (MACR, hydroxyacetone and methyl glyoxal. MIM2 is mass-conserving with respect to carbon, including CO2 as well. Therefore, it is suitable for studies assessing carbon monoxide (CO from biogenic sources, as well as for studies focused on the carbon cycle. Compared to MIM, MIM2 considers new species like acetaldehyde (CH3CHO, propene (CH2=CHCH3 and glyoxal (CHOCHO with global chemical production rates for the year 2005 of 7.3, 9.5 and 33.8 Tg/yr, respectively. Our new mechanism is expected to substantially improve the results of atmospheric chemistry models by more

  19. Effect of titanium oxide nanoparticle incorporation into nm thick coatings deposited using an atmospheric pressure plasma.

    Science.gov (United States)

    Denis, Dowling P; Barry, Twomey; Gerry, Byrne

    2010-04-01

    This study reports on the use of an atmospheric plasma technique to incorporate metal oxide nanoparticles into nm thick siloxane coatings. Titanium dioxide (TiO2) particles with diameters of 30-80 nm, were mixed with a number of different siloxanes-polydimethylsiloxane, hexamethyldisiloxane and tetraethylorthosilicate (TEOS). The TiO2/TEOS mixture was found to give the most stable suspension, possibly due to the higher surface tension of TEOS compared with the other siloxanes. TiO2/TEOS mixtures with 2 to 10% by weight of the metal oxide were prepared and were then nebulised into a helium/oxygen atmospheric plasma. Polyethylene terepthalate (PET) and silicon wafer substrates were passed through this plasma using a reel-to-reel substrate manipulation system. SEM combined with EDX was used to examine the distribution of the metal oxide particles in the resultant coatings. The TEOS coating thickness without TiO2 addition was 9 nm. The composite coating consisted of a relatively homogeneous distribution of small agglomerates of the TiO2 nanoparticles in TEOS. A linear increase in the titanium surface concentration was observed with increase in the quantity of TiO2 added into the siloxane precursor. The chemical functionality of the siloxane coating was examined using FTIR spectroscopy and no significant spectrum differences was observed with the incorporation of the different concentrations of TiO2 into the polymer. There were also no changes observed in coating surface energy with TiO2 incorporation. Coating morphology was examined using optical profilometry and surface roughness (Ra) values increased from typical values of 0.8 nm for the TEOS coating to 4.1 nm for the TiO2/TEOS coating. The adhesion of the deposited coatings was compared using fragmentation tests. These were carried out through uniaxial tensile loading. The coating cracking pattern after applied strain of 20% was not observed to change significantly with the addition of TiO2 into the siloxane. PMID

  20. Nitrogen oxide air pollution: atmospheric chemistry. 1979-August, 1980 (citations from the NTIS data base). Report for 1979-Aug 80

    Energy Technology Data Exchange (ETDEWEB)

    Cavagnaro, D.M.

    1980-10-01

    Photochemical air pollution models, smog chemistry and reactivity, and SSt exhaust effects are covered in the bibliography. Auroral and upper atmospheric chemistry, and photochemistry of naturally occurring nitrogen oxides are excluded. (This updated bibliography contains 63 citations, 40 of which are new entries to the previous edition.)

  1. Influence of the atmospheric species water, oxygen, nitrogen and carbon dioxide on the degradation of aluminum doped zinc oxide layers

    NARCIS (Netherlands)

    Theelen, M.; Dasgupta, S.; Vroon, Z.; Kniknie, B.; Barreau, N.; Berkum, J. van; Zeman, M.

    2014-01-01

    Aluminum doped zinc oxide (ZnO:Al) layers were exposed to the atmospheric gases carbon dioxide (CO2), oxygen (O2), nitrogen (N 2) and air as well as liquid H2O purged with these gases, in order to investigate the chemical degradation behavior of these layers. The samples were analyzed by electrical,

  2. Effect of oxygen level on the oxidative stability of two different retail pork products stored using modified atmosphere packaging (MAP)

    DEFF Research Database (Denmark)

    Spanos, Dimitrios; Ann Tørngren, Mari; Christensen, Mette;

    2016-01-01

    The characteristics and the oxidative stability of pork steaks and of pork mince were investigated during 2, 5 and 7 days of refrigerated storage using oxygen (O2) levels of 0%, 20%, 50% and 80% in modified atmosphere packaging (MAP). Steaks stored during 7 days were not affected by an increase...

  3. Effect of Kovar alloy oxidized in simulated N2/H2O atmosphere on its sealing with glass

    Institute of Scientific and Technical Information of China (English)

    Dawei Luo; Wenbo Leng; Zhuoshen Shen

    2008-01-01

    The effect of Kovar alloy oxidized in simulated field atmosphere on its sealing with glass was studied in this article. After Kovar plates and pins were preoxidized in N2 with 0℃, 10℃ and 20℃ dew points at 1000℃ for different times, Fe3O4 and Fe2O3 existed in the oxidation products on Kovar surface, and the quantity of Fe2O3 increased with increasing dew point and oxidation time.Then they were sealed with borosilicate glass insulator at 1030℃ for 20 min. The results indicated that the type and quantity of oxidation products would directly influence the quality of glass-to-metal seals. With the increase of oxidation products, gas bubbles in the glass insulator were more serious, the climbing height of glass along the pins was higher, and corrosion of Kovar pins caused from the molten glass was transformed from uniform to the localized.

  4. Atmospheric plasma generates oxygen atoms as oxidizing species in aqueous solutions

    Science.gov (United States)

    Mokhtar Hefny, Mohamed; Pattyn, Cedric; Lukes, Petr; Benedikt, Jan

    2016-10-01

    A remote microscale atmospheric pressure plasma jet (µAPPJ) with He, He/H2O, He/O2, and He/O2/H2O gas mixtures was used to study the transport of reactive species from the gas phase into the liquid and the following aqueous phase chemistry. The effects induced by the µAPPJ in water were quantitatively studied using phenol as a chemical probe and by measuring H2O2 concentration and pH values. These results were combined with the analysis of the absolute densities of the reactive species and the modeling of convective/diffusion transport and recombination reactions in the effluent of the plasma jet. Additionally, modified plasma jets were used to show that the role of emitted photons in aqueous chemistry is negligible for these plasma sources. The fastest phenol degradation was measured for the He/O2 plasma, followed by He/H2O, He/O2/H2O, and He plasmas. The modeled quantitative flux of O atoms into the liquid in the He/O2 plasma case was highly comparable with the phenol degradation rate and showed a very high transfer efficiency of reactive species from the plasma into the liquid, where more than half of the O atoms leaving the jet nozzle entered the liquid. The results indicate that the high oxidative effect of He/O2 plasma was primarily due to solvated O atoms, whereas OH radicals dominated the oxidative effects induced in water by plasmas with other gas mixtures. These findings help to understand, in a quantitative way, the complex interaction of cold atmospheric plasmas with aqueous solutions and will allow a better understanding of the interaction of these plasmas with water or buffered solutions containing biological macromolecules, microorganisms, or even eukaryotic cells. Additionally, the µAPPJ He/O2 plasma source seems to be an ideal tool for the generation of O atoms in aqueous solutions for any future studies of their reactivity.

  5. Mainz Isoprene Mechanism 2 (MIM2: an isoprene oxidation mechanism for regional and global atmospheric modelling

    Directory of Open Access Journals (Sweden)

    D. Taraborrelli

    2009-04-01

    Full Text Available We present an oxidation mechanism of intermediate size for isoprene (2-methyl-1,3-butadiene suitable for simulations in regional and global atmospheric chemistry models, which we call MIM2. It is a reduction of the corresponding detailed mechanism in the Master Chemical Mechanism (MCM v3.1 and intended as the second version of the well-established Mainz Isoprene Mechanism (MIM. Our aim is to improve the representation of tropospheric chemistry in regional and global models under all NOx regimes. We evaluate MIM2 and re-evaluate MIM through comparisons with MCM v3.1. We find that MIM and MIM2 compute similar O3, OH and isoprene mixing ratios. Unlike MIM, MIM2 produces small relative biases for NOx and organic nitrogen-containing species due to a good representation of the alkyl and peroxy acyl nitrates (RONO2 and RC(OOONO2. Moreover, MIM2 computes only small relative biases with respect to hydrogen peroxide (H2O2, methyl peroxide (CH3OOH, methanol (CH3OH, formaldehyde (HCHO, peroxy acetyl nitrate (PAN, and formic and acetic acids (HCOOH and CH3C(OOH, being always below ≈6% in all NOx scenarios studied. Most of the isoprene oxidation products are represented explicitly, including methyl vinyl ketone (MVK, methacrolein (MACR, hydroxyacetone and methyl glyoxal. MIM2 is mass-conserving with respect to carbon, including CO2 as well. Therefore, it is suitable for studies assessing carbon monoxide (CO from biogenic sources, as well as for studies focused on the carbon cycle. Compared to MIM, MIM2 considers new species like acetaldehyde (CH3CHO, propene (CH2=CHCH3 and glyoxal (CHOCHO with global chemical production rates for the year 2005 of 7.3, 9.5 and 33.8 Tg/yr, respectively. Our new mechanism is expected to substantially improve the results of atmospheric chemistry models by

  6. The magnetic and oxidation behavior of bare and silica-coated iron oxide nanoparticles synthesized by reverse co-precipitation of ferrous ion (Fe2+) in ambient atmosphere

    International Nuclear Information System (INIS)

    The synthesis of iron oxide nanoparticles, i.e., magnetite was attempted by using only ferrous ion (Fe2+) as a magnetite precursor, under an ambient atmosphere. The room temperature reverse co-precipitation method was used, by applying two synthesis protocols. The freshly prepared iron oxide was also immediately coated with Stöber silica (SiO2) layer, forming the coreshell structure. The phase, stoichiometry, crystallite and the particle size of the synthesized powders were determined by using X-ray diffraction (XRD) and transmission electron microscope (TEM), while the magnetic and oxidation behaviors were studied by using the vibrating sample magnetometer (VSM) and Mössbauer spectroscopy. Based on the results, the bare iron oxide nanoparticles are in the stoichiometry between the magnetite and the maghemite stoichiometry, i.e., oxidation occurs. This oxidation is depending on the synthesis protocols used. With the silica coating, the oxidation can be prevented, as suggested by the fits of Mössbauer spectra and low temperature magnetic measurement. - Highlights: • Synthesis of magnetite was attempted by using ferrous ion (Fe2+) in air. • The synthesized particle has a stoichiometry in between magnetite and maghemite. • Silica shell partly prevented the oxidation as suggested by magnetic and Mössbauer study

  7. Conductive zinc oxide thin film coatings by combustion chemical vapour deposition at atmospheric pressure

    International Nuclear Information System (INIS)

    We have established a combustion chemical vapour deposition (C-CVD) system for the deposition of zinc oxide (ZnO) at atmospheric pressure. This C-CVD process has the advantage of a short exposure of the substrates to the flame. It is also potentially applicable as an inline coating system. Fundamental studies were performed on undoped ZnO. The specific resistivity of these layers strongly depends on the film thickness and decreases with increasing thickness. As the lowest resistivities, values of about 2.0 · 10−1 Ωcm are achieved. Ultra-violet photoemission spectra show the valence band structure of the deposited ZnO. The work function and valence band edge were determined. UV–vis spectra were taken to investigate the transmission of the coated glass samples. From these spectra the band gap energy was obtained. Raman spectroscopy as well as infrared spectroscopy confirmed the presence of ordered ZnO crystallites. The X-ray diffraction verified this result and illustrates the hexagonal structure. In the mid-infrared range precursor deposits were detected for low substrate temperatures. - Highlights: ► Zinc oxide (ZnO) films are conductive in the range of 2.0 · 10−1 Ωcm. ► X-ray diffraction, Raman and infrared spectroscopy indicate crystalline ZnO films. ► Precursor deposits were proved within the films for low growing temperatures. ► Band gap energy changes are achieved due to different growing temperatures

  8. Modeling the possible role of iodine oxides in atmospheric new particle formation

    Directory of Open Access Journals (Sweden)

    S. Pechtl

    2006-01-01

    Full Text Available We studied the possible role of iodine oxides in atmospheric new particle formation with the one-dimensional marine boundary layer model MISTRA, which includes chemistry in the gas and aerosol phase as well as aerosol microphysics. The chemical reaction set focuses on halogen (Cl-Br-I chemistry. We included a two-step nucleation parameterization, where in the first step, the 'real' nucleation process is parameterized, i.e., the formation of cluster-sized nuclei via homogeneous condensation of gases. We considered both ternary sulfuric acid-ammonia-water nucleation and homomolecular homogeneous OIO nucleation. For the latter, we derived a parameterization based on combined laboratory-model studies. The second step of the nucleation parameterization treats the 'apparent' nucleation rate, i.e., the growth of clusters into the model's lowest size bin by condensable vapors such as OIO. We compared different scenarios for a clean marine versus a polluted continental background atmosphere. In every scenario, we assumed the air to move, independent of its origin, first over a coastal region (where it is exposed to surface fluxes of different reactive iodine precursors and later over the open ocean. According to these sensitivity studies, in the clean marine background atmosphere OIO can be responsible for both homogeneous nuclei formation and the subsequent growth of the clusters to detectable sizes. In contrast to this, in the continental case with its higher levels of pollutants, gas phase OIO mixing ratios, and hence related nucleation rates, are significantly lower. Compared to ternary H2SO4-NH3-H2O nucleation, homogeneous OIO nucleation can be neglected for new particle formation in this case, but OIO can contribute to early particle growth, i.e., to apparent nucleation rates. In general, we found OIO to be more important for the growth of newly formed particles than for the formation of new nuclei. According to our studies, observations of

  9. Fog composition at Baengnyeong Island in the Eastern Yellow Sea: detecting markers of aqueous atmospheric oxidations

    Directory of Open Access Journals (Sweden)

    A. J. Boris

    2015-09-01

    Full Text Available Samples of fog water were collected at Baengnyeong Island (BYI in the Yellow Sea during the summer of 2014. The most abundant chemical species in the fog water were NH4+ (mean of 2220 μM, NO3− (1260 μM, SO4−2 (730 μM, and Na+ (551 μM, with substantial contributions from other ions consistent with marine and biomass burning influence on some dates. The pH of the samples ranged between 3.48 and 5.00, with a mean of 3.94, intermediate within pH values of fog/cloud water reported previously in Southeast Asia. Back trajectories (72 h showed that high relative humidity (> 80 % was encountered upwind of the sampling site by all but one of the sampled air masses, and that the fog composition at BYI can be impacted by several different source regions, including the Sea of Japan, Northeastern China, and the East China Sea. Sulfur in the collected fog was highly oxidized: low S(IV concentrations were measured (mean of 2.36 μM in contrast to SO4−2 and in contrast to fog/cloud S(IV concentrations from pollutant source regions; organosulfate species were also observed and were most likely formed through aging of mainly biogenic volatile organic compounds. Low molecular mass organic acids were major contributors to total organic carbon (TOC; 36–69 %, comprising a fraction of TOC at the upper end of that seen in fogs and clouds in other polluted environments. Large contributions were observed from not only acetic and formic acids, but also oxalic, succinic, maleic, and other organic acids that can be produced in aqueous atmospheric organic processing (AAOP reactions. These samples of East Asian fog water containing highly oxidized components represent fog downwind of pollutant sources and can provide new insight into the fate of regional emissions. In particular, these samples demonstrate the result of extensive photochemical aging during multiday transport, including oxidation within wet aerosols and fogs.

  10. Fog composition at Baengnyeong Island in the eastern Yellow Sea: detecting markers of aqueous atmospheric oxidations

    Science.gov (United States)

    Boris, A. J.; Lee, T.; Park, T.; Choi, J.; Seo, S. J.; Collett, J. L., Jr.

    2016-01-01

    Samples of fog water were collected at Baengnyeong Island (BYI) in the Yellow Sea during the summer of 2014. The most abundant chemical species in the fog water were NH4+ (mean of 2220 µM), NO3- (1260 µM), SO4-2 (730 µM), and Na+ (551 µM), with substantial contributions from other species consistent with marine and biomass burning influence on some dates. The pH of the samples ranged between 3.48 and 5.00, with a mean of 3.94, intermediate within pH values of fog/cloud water reported previously in Southeast Asia. Back trajectories (72 h) showed that high relative humidity ( > 80 %) was encountered upwind of the sampling site by all but one of the sampled air masses, and that the fog composition at BYI can be impacted by several different source regions, including the Sea of Japan, southeastern China, northeastern China, and the East China Sea. Sulfur in the collected fog was highly oxidized: low S(IV) concentrations were measured (mean of 2.36 µM) in contrast to SO4-2 and in contrast to fog/cloud S(IV) concentrations from pollutant source regions; organosulfate species were also observed and were most likely formed through aging of mainly biogenic volatile organic compounds. Low-molecular-mass organic acids were major contributors to total organic carbon (TOC; 36-69 %), comprising a fraction of TOC at the upper end of that seen in fogs and clouds in other polluted environments. Large contributions were observed from not only acetic and formic acids but also oxalic, succinic, maleic, and other organic acids that can be produced in aqueous atmospheric organic processing (AAOP) reactions. These samples of East Asian fog water containing highly oxidized components represent fog downwind of pollutant sources and can provide new insight into the fate of regional emissions. In particular, these samples demonstrate the result of extensive photochemical aging during multiday transport, including oxidation within wet aerosols and fogs.

  11. Fighting global warming by greenhouse gas removal: destroying atmospheric nitrous oxide thanks to synergies between two breakthrough technologies.

    Science.gov (United States)

    Ming, Tingzhen; de Richter, Renaud; Shen, Sheng; Caillol, Sylvain

    2016-04-01

    Even if humans stop discharging CO2 into the atmosphere, the average global temperature will still increase during this century. A lot of research has been devoted to prevent and reduce the amount of carbon dioxide (CO2) emissions in the atmosphere, in order to mitigate the effects of climate change. Carbon capture and sequestration (CCS) is one of the technologies that might help to limit emissions. In complement, direct CO2 removal from the atmosphere has been proposed after the emissions have occurred. But, the removal of all the excess anthropogenic atmospheric CO2 will not be enough, due to the fact that CO2 outgases from the ocean as its solubility is dependent of its atmospheric partial pressure. Bringing back the Earth average surface temperature to pre-industrial levels would require the removal of all previously emitted CO2. Thus, the atmospheric removal of other greenhouse gases is necessary. This article proposes a combination of disrupting techniques to transform nitrous oxide (N2O), the third most important greenhouse gas (GHG) in terms of current radiative forcing, which is harmful for the ozone layer and possesses quite high global warming potential. Although several scientific publications cite "greenhouse gas removal," to our knowledge, it is the first time innovative solutions are proposed to effectively remove N2O or other GHGs from the atmosphere other than CO2. PMID:26805926

  12. Fighting global warming by greenhouse gas removal: destroying atmospheric nitrous oxide thanks to synergies between two breakthrough technologies.

    Science.gov (United States)

    Ming, Tingzhen; de Richter, Renaud; Shen, Sheng; Caillol, Sylvain

    2016-04-01

    Even if humans stop discharging CO2 into the atmosphere, the average global temperature will still increase during this century. A lot of research has been devoted to prevent and reduce the amount of carbon dioxide (CO2) emissions in the atmosphere, in order to mitigate the effects of climate change. Carbon capture and sequestration (CCS) is one of the technologies that might help to limit emissions. In complement, direct CO2 removal from the atmosphere has been proposed after the emissions have occurred. But, the removal of all the excess anthropogenic atmospheric CO2 will not be enough, due to the fact that CO2 outgases from the ocean as its solubility is dependent of its atmospheric partial pressure. Bringing back the Earth average surface temperature to pre-industrial levels would require the removal of all previously emitted CO2. Thus, the atmospheric removal of other greenhouse gases is necessary. This article proposes a combination of disrupting techniques to transform nitrous oxide (N2O), the third most important greenhouse gas (GHG) in terms of current radiative forcing, which is harmful for the ozone layer and possesses quite high global warming potential. Although several scientific publications cite "greenhouse gas removal," to our knowledge, it is the first time innovative solutions are proposed to effectively remove N2O or other GHGs from the atmosphere other than CO2.

  13. Coarsening of Pd nanoparticles in an oxidizing atmosphere studied by in situ TEM

    Science.gov (United States)

    Simonsen, Søren Bredmose; Chorkendorff, Ib; Dahl, Søren; Skoglundh, Magnus; Helveg, Stig

    2016-06-01

    The coarsening of supported palladium nanoparticles in an oxidizing atmosphere was studied in situ by means of transmission electron microscopy (TEM). Specifically, the Pd nanoparticles were dispersed on a planar and amorphous Al2O3 support and were observed during the exposure to 10 mbar technical air at 650 °C. Time-resolved TEM image series reveal that the Pd nanoparticles were immobile and that a few percent of the nanoparticles grew or shrank, indicating a coarsening process mediated by the Ostwald ripening mechanism. The TEM image contrast suggests that the largest nanoparticles tended to wet the Al2O3 support to a higher degree than the smaller nanoparticles and that the distribution of projected particle sizes consequently broadens by the appearance of an asymmetric tail toward the larger particle sizes. A comparison with computer simulations based on a simple mean-field model for the Ostwald ripening process indicates that the observed change in the particle size distribution can be accounted for by wetting of the Al2O3 support by the larger Pd nanoparticles.

  14. Optimizing the electrical excitation of an atmospheric pressure plasma advanced oxidation process.

    Science.gov (United States)

    Olszewski, P; Li, J F; Liu, D X; Walsh, J L

    2014-08-30

    The impact of pulse-modulated generation of atmospheric pressure plasma on the efficiency of organic dye degradation has been investigated. Aqueous samples of methyl orange were exposed to low temperature air plasma and the degradation efficiency was determined by absorbance spectroscopy. The plasma was driven at a constant frequency of 35kHz with a duty cycle of 25%, 50%, 75% and 100%. Relative concentrations of dissolved nitrogen oxides, pH, conductivity and the time evolution of gas phase ozone were measured to identify key parameters responsible for the changes observed in degradation efficiency. The results indicate that pulse modulation significantly improved dye degradation efficiency, with a plasma pulsed at 25% duty showing a two-fold enhancement. Additionally, pulse modulation led to a reduction in the amount of nitrate contamination added to the solution by the plasma. The results clearly demonstrate that optimization of the electrical excitation of the plasma can enhance both degradation efficiency and the final water quality.

  15. Effect of atmospheric oxidative plasma treatments on polypropylenic fibers surface: Characterization and reaction mechanisms

    Energy Technology Data Exchange (ETDEWEB)

    Nisticò, Roberto, E-mail: roberto.nistico@unito.it [University of Torino, Department of Chemistry and NIS Centre of Excellence, Via P. Giuria 7, 10125 Torino (Italy); Magnacca, Giuliana [University of Torino, Department of Chemistry and NIS Centre of Excellence, Via P. Giuria 7, 10125 Torino (Italy); Faga, Maria Giulia; Gautier, Giovanna [CNR-IMAMOTER, Strada delle Cacce 73, 10135 Torino (Italy); D’Angelo, Domenico; Ciancio, Emanuele [Clean-NT Lab, Environment Park S.p.A., Via Livorno 60, 10144 Torino (Italy); Lamberti, Roberta; Martorana, Selanna [Herniamesh S.r.l., Via F.lli Meliga 1/C, 10034 Chivasso (Italy)

    2013-08-15

    Atmospheric pressure plasma-dielectric barrier discharge (APP-DBD, open chamber configuration) was used to functionalize polypropylene (PP) fibers surface in order to generate oxidized-reactive groups such as hydroperoxides, alcohols and carbonyl species (i.e. ketones and others). Such a species increased the surface polarity, without causing material degradation. Three different types of plasma mixture (He, He/O{sub 2}, He/O{sub 2}/H{sub 2}O) under three different values of applied power (750, 1050, 1400 W) were investigated. The formed plasma species (O{sub 2}{sup +}, O single atom and OH radical) and their distribution were monitored via optical emission spectrometry (OES) measurements, and the plasma effects on PP surface species formation were followed by X-ray photoemission spectroscopy (XPS). Results allowed to better understand the reaction pathways between plasma phase and PP fibers. In fact, two reaction mechanisms were proposed, the first one concerning the plasma phase reactions and the second one involving material surface modifications.

  16. Structural properties of zinc oxide deposited using atmospheric pressure combustion chemical vapour deposition

    International Nuclear Information System (INIS)

    In this study the deposition of thin zinc oxide (ZnO) films under atmospheric pressure conditions was investigated. The deposition technique applied was combustion chemical vapour deposition (CCVD), at which a propane–air mixture was combusted in a burner. Dissolved zinc nitrate was used as precursor, which was guided as aerosol droplets by the processing gas flow directly into the reaction zone. Fundamental investigations were performed to form undoped ZnO. The structural properties of the films were analysed in dependence of the substrate temperature during the coating process. The presence of crystalline ZnO structures was proved and differences in film growth and crystallite sizes are revealed. Additionally, the particles generated by the CCVD-flame are characterised. The thin films showed a slight excess of Zn and several states of binding energy could be observed by fitting the core level spectra. Scanning and transmission electron microscopy also indicated ordered structures and additionally different orientations of crystallites were observed. - Highlights: • Columnar growth structures of ZnO by CCVD were observed. • The presence of polycrystalline ZnO with (002) as main orientation was confirmed. • Initial particles significantly differ from crystallite sizes of the resulting films. • The films show an excess of Zn with a Zn-to-O ratio of around 1.7

  17. Structural properties of zinc oxide deposited using atmospheric pressure combustion chemical vapour deposition

    Energy Technology Data Exchange (ETDEWEB)

    Zunke, I., E-mail: iz@innovent-jena.de [Innovent e.V. Technology Development, Department of Surface Engineering, Prüssingstr. 27B, 07745 Jena (Germany); Wolf, S. [University of Jena, Institute for Solid State Physics, Helmholtzweg 3/5, 07745 Jena (Germany); Heft, A.; Schimanski, A.; Grünler, B. [Innovent e.V. Technology Development, Department of Surface Engineering, Prüssingstr. 27B, 07745 Jena (Germany); Ronning, C.; Seidel, P. [University of Jena, Institute for Solid State Physics, Helmholtzweg 3/5, 07745 Jena (Germany)

    2014-08-28

    In this study the deposition of thin zinc oxide (ZnO) films under atmospheric pressure conditions was investigated. The deposition technique applied was combustion chemical vapour deposition (CCVD), at which a propane–air mixture was combusted in a burner. Dissolved zinc nitrate was used as precursor, which was guided as aerosol droplets by the processing gas flow directly into the reaction zone. Fundamental investigations were performed to form undoped ZnO. The structural properties of the films were analysed in dependence of the substrate temperature during the coating process. The presence of crystalline ZnO structures was proved and differences in film growth and crystallite sizes are revealed. Additionally, the particles generated by the CCVD-flame are characterised. The thin films showed a slight excess of Zn and several states of binding energy could be observed by fitting the core level spectra. Scanning and transmission electron microscopy also indicated ordered structures and additionally different orientations of crystallites were observed. - Highlights: • Columnar growth structures of ZnO by CCVD were observed. • The presence of polycrystalline ZnO with (002) as main orientation was confirmed. • Initial particles significantly differ from crystallite sizes of the resulting films. • The films show an excess of Zn with a Zn-to-O ratio of around 1.7.

  18. Fabrication and electrochemical performance of solid oxide fuel cell components by atmospheric and suspension plasma spray

    Institute of Scientific and Technical Information of China (English)

    XIA Wei-sheng; YANG Yun-zhen; ZHANG Hai-ou; WANG Gui-lan

    2009-01-01

    The theory of functionally graded material (FGM) was applied in the fabrication process of PEN (Positive- Electrolyte-Negative),the core component of solid oxide fuel cell (SOFC).To enhance its electrochemical performance,the functionally graded PEN of planar SOFC was prepared by atmospheric plasma spray (APS).The cross-sectional SEM micrograph and element energy spectrum of the resultant PEN were analyzed.Its interface resistance was also compared with that without the graded layers to investigate the electrochemical performance enhanced by the functionally graded layers.Moreover,a new process,suspension plasma spray (SPS) was applied to preparing the SOFC electrolyte.Higher densification of the coating by SPS,1.61%,is observed,which is helpful to effectively improve its electrical conductivity.The grain size of the electrolyte coating fabricated by SPS is also smaller than that by APS,which is more favourable to obtain the dense electrolyte coatings.To sum up,all mentioned above can prove that the hybrid process of APS and SPS could be a better approach to fabricate the PEN of SOFC stacks,in which APS is for porous electrodes and SPS for dense electrolyte.

  19. Torrefaction of agricultural by-products (abstract)

    Science.gov (United States)

    Torrefaction of biomass involves heating at 200°C-300°C under inert atmosphere to remove volatiles and produce materials with higher energy values and low moisture. Agricultural by-products, such as apple, grape, olive, and tomato pomaces as well as almond and walnut shells, were torrefied at differ...

  20. Multi-scale Model of Residual Strength of 2D Plain Weave C/SiC Composites in Oxidation Atmosphere

    Science.gov (United States)

    Chen, Xihui; Sun, Zhigang; Sun, Jianfen; Song, Yingdong

    2016-06-01

    Multi-scale models play an important role in capturing the nonlinear response of woven carbon fiber reinforced ceramic matrix composites. In plain weave carbon fiber/silicon carbon (C/SiC) composites, the carbon fibers and interphases will be oxidized at elevated temperature and the strength of the composite will be degraded when oxygen enters micro-cracks formed in the as-produced parts due to the mismatch in thermal properties between constituents. As a result of the oxidation on fiber surface, fiber shows a notch-like morphology. In this paper, the change rule of fiber notch depth is fitted by circular function. And a multi-scale model based upon the change rule of fiber notch depth is developed to simulate the residual strength and post-oxidation stress-strain curves of the composite. The multi-scale model is able to accurately predict the residual strength and post-oxidation stress-strain curves of the composite. Besides, the simulated residual strength and post-oxidation stress-strain curves of 2D plain weave C/SiC composites in oxidation atmosphere show good agreements with experimental results. Furthermore, the oxidation time and temperature of the composite are investigated to show their influences upon the residual strength and post-oxidation stress-strain curves of plain weave C/SiC composites.

  1. Enhanced Removal of Biogenic Hydrocarbons in Power Plant Plumes Constrains the Dependence of Atmospheric Hydroxyl Concentrations on Nitrogen Oxides

    Science.gov (United States)

    De Gouw, J. A.; Trainer, M.; Parrish, D. D.; Brown, S. S.; Edwards, P.; Gilman, J.; Graus, M.; Hanisco, T. F.; Kaiser, J.; Keutsch, F. N.; Kim, S. W.; Lerner, B. M.; Neuman, J. A.; Pollack, I. B.; Roberts, J. M.; Ryerson, T. B.; Veres, P. R.; Warneke, C.; Wolfe, G.

    2015-12-01

    Hydroxyl (OH) radicals in the atmosphere provide one of the main chemical mechanisms for the removal of trace gases. OH plays a central role in determining the atmospheric lifetime and radiative forcing of greenhouse gases like methane. OH also plays a major role in the oxidation of organic trace gases, which can lead to formation of secondary pollutants such as ozone and PM2.5. Due to its very short atmospheric lifetime of seconds or less, OH concentrations are extremely variable in space and time, which makes measurements and their interpretation very challenging. Several recent measurements have yielded higher than expected OH concentrations. To explain these would require the existence of unidentified, radical recycling processes, but issues with the measurements themselves are also still being discussed. During the NOAA airborne SENEX study in the Southeast U.S., the biogenic hydrocarbons isoprene and monoterpenes were consistently found to have lower mixing ratios in air masses with enhanced nitrogen oxides from power plants. We attribute this to faster oxidation rates of biogenic hydrocarbons due to increased concentrations of OH in the power plant plumes. Measurements at different downwind distances from the Scherer and Harllee Branch coal-fired power plants near Atlanta are used to constrain the dependence of OH on nitrogen oxides. It is found that OH concentrations were highest at nitrogen dioxide concentrations of 1-2 ppbv and decreased at higher and at lower concentrations. These findings agree with the expected dependence of OH on nitrogen oxide concentrations, but do not appear to be consistent with the reports in the literature that have shown high OH concentrations in regions of the atmosphere with high biogenic emissions and low NOx concentrations that would require unidentified radical recycling processes to be explained.

  2. The magnetic and oxidation behavior of bare and silica-coated iron oxide nanoparticles synthesized by reverse co-precipitation of ferrous ion (Fe2+) in ambient atmosphere

    Science.gov (United States)

    Mahmed, N.; Heczko, O.; Lancok, A.; Hannula, S.-P.

    2014-03-01

    The synthesis of iron oxide nanoparticles, i.e., magnetite was attempted by using only ferrous ion (Fe2+) as a magnetite precursor, under an ambient atmosphere. The room temperature reverse co-precipitation method was used, by applying two synthesis protocols. The freshly prepared iron oxide was also immediately coated with Stöber silica (SiO2) layer, forming the coreshell structure. The phase, stoichiometry, crystallite and the particle size of the synthesized powders were determined by using X-ray diffraction (XRD) and transmission electron microscope (TEM), while the magnetic and oxidation behaviors were studied by using the vibrating sample magnetometer (VSM) and Mössbauer spectroscopy. Based on the results, the bare iron oxide nanoparticles are in the stoichiometry between the magnetite and the maghemite stoichiometry, i.e., oxidation occurs. This oxidation is depending on the synthesis protocols used. With the silica coating, the oxidation can be prevented, as suggested by the fits of Mössbauer spectra and low temperature magnetic measurement.

  3. Corrosion of Iron and Four Commercial Steels in a Cl-Containing Oxidizing Atmosphere at 500~600℃

    Institute of Scientific and Technical Information of China (English)

    Ke ZHANG; Yah NIU; Chaoliu ZENG; Weitao WU

    2004-01-01

    The corrosion behaviors of Fe and four commercial steels with different Cr contents were investigated in an oxidizing atmosphere containing HCI at 500~600℃, which simulated the environment to which materials are usually exposed in waste incineration. All the test materials underwent an accelerated corrosion in this atmosphere and small amounts of chlorine could be detected at the metal/scale interface. The corrosion mechanism is discussed on the basis of thermodynamic considerations for the reactions between metals and mixed O-CI gases.

  4. Standard method for continuous measurement of nitric oxide, nitrogen dioxide, and ozone in the atmosphere. [Calorimetrically using Griess Reagent

    Energy Technology Data Exchange (ETDEWEB)

    1975-01-01

    Nitrogen dioxide is absorbed from the atmosphere in a modified Griess reagent which contains 0.5 percent sulfanilic acid and 50 ppM of N-(1-naphthyl)-ethylene diamine hydrochloride in 5 percent acetic acid that produces a red dye. The red dye is measured continuously in a recording colorimeter by comparison with a blank of unreacted reagent. Nitric oxide from the atmosphere passes through the absorber practically unaffected and is oxidized to nitrogen dioxide by bubbling through a dilute permanganate solution prior to determination with modified Griess reagent in a separate cell. Optionally, ozone in the air sample may be determined in a third absorber-colorimeter cell unit by adding about 0.5 to 1.0 ppM of pure nitric oxide to another sample of air and noting the increase in nitrogen dioxide level due to the rapid oxidation of nitric oxide to nitrogen dioxide by ozone. The overall accuracy of the results of the method is +-10 percent. (BLM)

  5. Oxidation and nitration of tyrosine by ozone and nitrogen dioxide: reaction mechanisms and biological and atmospheric implications.

    Science.gov (United States)

    Sandhiya, L; Kolandaivel, P; Senthilkumar, K

    2014-04-01

    The nitration of tyrosine by atmospheric oxidants, O3 and NO2, is an important cause for the spread of allergenic diseases. In the present study, the mechanism and pathways for the reaction of tyrosine with the atmospheric oxidants O3 and NO2 are studied using DFT-M06-2X, B3LYP, and B3LYP-D methods with the 6-311+G(d,p) basis set. The energy barrier for the initial oxidation reactions is also calculated at the CCSD(T)/6-31+G(d,p) level of theory. The reaction is studied in gas, aqueous, and lipid media. The initial oxidation of tyrosine by O3 proceeds by H atom abstraction and addition reactions and leads to the formation of six different intermediates. The subsequent nitration reaction is studied for all the intermediates, and the results show that the nitration affects both the side chain and the aromatic ring of tyrosine. The rate constant of the favorable oxidation and nitration reaction is calculated using variational transition state theory over the temperature range of 278-350 K. The spectral properties of the oxidation and nitration products are calculated at the TD-M06-2X/6-311+G(d,p) level of theory. The fate of the tyrosine radical intermediate is studied by its reaction with glutathione antioxidant. This study provides an enhanced understanding of the oxidation and nitration of tyrosine by O3 and NO2 in the context of improving the air quality and reducing the allergic diseases.

  6. Exploring Atmospheric Aqueous Chemistry (and Secondary Organic Aerosol Formation) through OH Radical Oxidation Experiments, Droplet Evaporation and Chemical Modeling

    Science.gov (United States)

    Turpin, B. J.; Kirkland, J. R.; Lim, Y. B.; Ortiz-Montalvo, D. L.; Sullivan, A.; Häkkinen, S.; Schwier, A. N.; Tan, Y.; McNeill, V. F.; Collett, J. L.; Skog, K.; Keutsch, F. N.; Sareen, N.; Carlton, A. G.; Decesari, S.; Facchini, C.

    2013-12-01

    Gas phase photochemistry fragments and oxidizes organic emissions, making water-soluble organics ubiquitous in the atmosphere. My group and others have found that several water-soluble compounds react further in the aqueous phase forming low volatility products under atmospherically-relevant conditions (i.e., in clouds, fogs and wet aerosols). Thus, secondary organic aerosol can form as a result of gas followed by aqueous chemistry (aqSOA). We have used aqueous OH radical oxidation experiments coupled with product analysis and chemical modeling to validate and refine the aqueous chemistry of glyoxal, methylglyoxal, glycolaldehyde, and acetic acid. The resulting chemical model has provided insights into the differences between oxidation chemistry in clouds and in wet aerosols. Further, we conducted droplet evaporation experiments to characterize the volatility of the products. Most recently, we have conducted aqueous OH radical oxidation experiments with ambient mixtures of water-soluble gases to identify additional atmospherically-important precursors and products. Specifically, we scrubbed water-soluble gases from the ambient air in the Po Valley, Italy using four mist chambers in parallel, operating at 25-30 L min-1. Aqueous OH radical oxidation experiments and control experiments were conducted with these mixtures (total organic carbon ≈ 100 μM-C). OH radicals (3.5E-2 μM [OH] s-1) were generated by photolyzing H2O2. Precursors and products were characterized using electrospray ionization mass spectrometry (ESI-MS), ion chromatography (IC), IC-ESI-MS, and ultra high resolution Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR-MS). Chemical modeling suggests that organic acids (e.g., oxalate, pyruvate, glycolate) are major products of OH radical oxidation at cloud-relevant concentrations, whereas organic radical - radical reactions result in the formation of oligomers in wet aerosols. Products of cloud chemistry and droplet evaporation have

  7. Atmospheric oxidation of phenanthrene initiated by OH radicals in the presence of O2 and NOx - A theoretical study.

    Science.gov (United States)

    Zhao, Nan; Zhang, Qingzhu; Wang, Wenxing

    2016-09-01

    Phenanthrene (Phe) is one of the most abundant polycyclic aromatic hydrocarbons (PAHs) observed in polluted urban atmosphere. The most important atmospheric loss process of Phe is the reaction with OH radicals. The present work investigated OH radical-initiated atmospheric degradation of Phe in the presence of O2 and NOx. The possible reaction mechanism was elucidated by density functional theory (DFT) calculations. Calculations show that the main products are a series of ring-retaining and ring-opening oxygenated PAHs containing phenanthrol, phenanthones, phenanthrenequinone, and dialdehydes. Rice-Ramsperger-Kassel-Marcus (RRKM) theory was employed to evaluate the rate constants for the initial steps of Phe with OH. The atmospheric lifetime of Phe relative to gas-phase reactions with OH is estimated to be 4.6h, based on the calculated overall rate constant of 3.02×10(-11)cm(3) molecule(-1)s(-1) at 298K and 1atm. Combined with available experimental data, this work also provides a comprehensive investigation of the formation mechanism of oxygenated PAHs in the atmospheric oxidation process of phenanthrene and should help to clarify its potential health risk. PMID:27169729

  8. The atmospheric oxidation of dimethyl, diethyl, and diisopropyl ethers. The role of the intramolecular hydrogen shift in peroxy radicals.

    Science.gov (United States)

    Wang, Sainan; Wang, Liming

    2016-03-21

    The atmospheric oxidation mechanisms of dimethyl ether (DME), diethyl ether (DEE) and diisopropyl ether (DiPE) are studied by using quantum chemistry and unimolecular reaction theory (RRKM-ME) calculations. For the peroxy radical CH3OCH2O2˙ from DME, a barrier height of ∼ 85 kJ mol(-1) is found for its intramolecular H-shift to ˙CH2OCH2OOH, which can recombine rapidly with the atmospheric O2. RRKM-ME calculations obtain an effective rate of ∼ 0.1 s(-1) at 298 K for the formation of ˙O2CH2OCH2OOH. For similar radicals in DEE and DiPE, effective rates are 1.6 s(-1) and 1.1 s(-1), respectively. In the atmosphere, these unimolecular reactions are fast enough to compete with the bimolecular reactions with NO and/or HO2, especially when [NO] is low. The fates of radicals after the H-shifts are also examined here. Several subsequent reactions are found to recycle OH radicals. New mechanisms are proposed on the basis of present calculations and are consistent with previous experimental results. In the atmosphere, the routes via H-shifts represent an auto-oxidation of these ethers with no involvement of NOx and therefore no O3 formation, and also a self-cleaning mechanism of organic compounds due to recycling of OH radicals. Some of the end products are highly oxidized with multifunctional groups and high O : C ratios, suggesting their low volatility and potential contribution to secondary organic aerosols. PMID:26907474

  9. Characteristic of coal combustion in oxygen/carbon dioxide atmosphere and nitric oxide release during this process

    International Nuclear Information System (INIS)

    Combustion characteristic of a bituminous coal and an anthracite coal in oxygen/carbon dioxide (O2/CO2) atmosphere is investigated in a thermogravimetric (TG) analyzer. The characteristic parameters, which are deduced from the TG-DTG (differential thermogravimetric) curves, show that the coal combustion process is basically kept consistent in O2/CO2 and O2/N2 atmosphere at the O2 concentration of 20%. The Coats-Redfern method with the reaction order of 1.25 could perfectly describe the combustion process in these two different atmospheres through the calculation of the kinetic parameters for the two coals. Nitric oxide (NO) release is concentrated in a narrower time period in O2/CO2 atmosphere compared with the one in O2/N2 atmosphere during the coal combustion process. Though the high value of the NO release rate peak, the total conversion of the fuel-N to NO is strongly depressed in O2/CO2 atmosphere, and at 1473 K, the conversion is reduced by 28.99% for the bituminous coal and 22.54% for the anthracite coal, respectively. When O2 concentration is increased from 20% to 40% in O2/CO2 atmosphere, the coal combustion property is obviously improved with the shift of the whole process into the lower temperature zone and the more intensive of the reaction occurrence in a narrower temperature range. However, the total fuel-N to NO conversion is increased accordingly. For bituminous coal the increase is 17.22% at 1073 K and 20.51% at 1173 K, and for anthracite coal the increase is 15.73% at 1073 K and 16.19% at 1173 K.

  10. High throughput measurement of high temperature strength of ceramics in controlled atmosphere and its use on solid oxide fuel cell anode supports

    DEFF Research Database (Denmark)

    Frandsen, Henrik Lund; Curran, Declan; Rasmussen, Steffen;

    2014-01-01

    In the development of structural and functional ceramics for high temperature electrochemical conversion devices such as solid oxide fuel cells, their mechanical properties must be tested at operational conditions, i.e. at high temperature and controlled atmospheres. Furthermore, characterization...

  11. Oxidant Component In The Martian Atmosphere Observed By Mex/pfs

    Science.gov (United States)

    Kasaba, Yasumasa; Aoki, S.; Nakagawa, H.; Murata, I.; Formisano, V.; Giuranna, M.; Geminale, A.

    2010-10-01

    Previous observations have been suggested that the large and fast variations of methane in the Martian atmosphere would be caused by oxidation loss with H2O2. These results also suggested that H2O2 would be produced in quantities much larger than foreseen by water photochemistry during dust storms and dust devils by means of electrostatic charging of the dust grains. However, past ground-based observations of H2O2 mixing ratios were few and contradictory with photochemical model. In this study, we tried to detect the Martian H2O2 from the continuous observations with Planetary Fourier Spectroscopy (PFS) onboard Mars Express (MEX) over several Mars years. Based on the possible H2O2 line at 362 cm-1 which is not contaminated by strong water lines, the derived H2O2 mixing ratio shows varies between 0 and 50 ppb with an average and standard deviation of 20-30 ppb, respectively. The result itself is good consistent with the photochemical model. However, the credibility of this innovative result shall be established. We tried to evaluate the results with the one in other lines at 379, 416 and 433 cm-1. At the moment, the results from these four lines are inconsistent. In order to clarify the true absorption of H2O2, the following two things are tried: (1) The removal of the side lobe effects in the instrumental function (i.e. Adoption of the apodization into the interferogram analysis.) (2) Identification of the artificial enhancement at the H2O2 absorption lines (i.e., the H2O2 absorption in the condition with very low H2O mixing ratio. Less absorption shall be expected in average.). This paper will reflects the updated results based this trials. In addition, we will also briefly report our recent ground-based activities, i.e., (1) submm observations of Martian minor elements and (2) the development of infrared heterodyne spectrometer.

  12. Preparation of Superfine Transparent Iron Oxide with Ferrous Sulphate from the By-product of Titanium Dioxide Production%钛白副产硫酸亚铁制备超细透明氧化铁黄研究

    Institute of Scientific and Technical Information of China (English)

    李金磊; 胡兵; 宋建民

    2012-01-01

    以钛白粉厂副产物硫酸亚铁为原料,以氨水为沉淀剂,采用空气氧化法制备超细透明氧化铁黄.分别研究了影响晶种形成和晶体生长的主要影响因素.通过优化实验,得出了最佳工艺条件.晶种制备阶段:温度为30℃,空气流量为2L/min,溶液的pH为4~6,搅拌速度为400r/min,Fe2+浓度为1mol/L.晶体生长阶段:温度为85℃,空气流量为2L/min,溶液pH为4~6.%A process of preparing superfine transparent iron oxide with the by-products of ferrous sulfate was described.The process included two steps:the yielding and growing of crystals.Several key factors affecting the two steps were studied respectively such as effects of Fe2+ concentration,air flow rate and stirring rate and reaction temperature and pH values.

  13. Were ancient granitoid compositions influenced by contemporaneous atmospheric and hydrosphere oxidation states?Were ancient granitoid compositions influenced by contemporaneous atmospheric and hydrosphere oxidation states?

    Science.gov (United States)

    Jagoutz, Oliver

    2014-05-01

    A fundamental shift in the nature of granitoids occurs at approximately the Archean-Proterozoic boundary. Archean crust is dominated Na-rich tonalite-trondhjemite-granodiorites (TTGs), whereas post-Archean granitoids are characterized by K-rich granodiorite-granite (GG). Due to the HREE depletion commonly found in TTGs indicating the presence of residual garnet, many researchers have proposed that the difference in Na/K is related to the deeper melting depth of the TTG parental liquids. Here I present a compilation of the relevant experimental data, documenting that no correlation exists between the Na/K of derivative felsic liquids and the pressure of partial melting/fractional crystallization. Instead, the Na/K ratio of the felsic liquid best correlates with the Na/K ratio of the source. This implies that in Archean time the source material of TTG rocks must have been Na/K enriched relative to the modern. Modern granitoids are dominantly formed in a supra subduction zone environment, where a feedback loop exists between subducted materials (oceanic crust and sediments) and arc magmatism. Sea-floor weathering and the Na/K of the altered oceanic crust strongly depends on f(O2) conditions during alteration, which likely changed with earth history. During alteration under oxidized condition K2O is fixated due to the formation of celadonite (K-Mica), wheres during anoxic condition saponite (Na-Smectite) is the stable alteration mineral. I propose that the rise of oxygen at 2600-2400 Ma triggered associated changes in f(O2) seafloor alteration conditions. The change in the dominant seafloor alteration mineral from reduced to oxidized causes a change in the nature of the arc magma source and provides a possible explanation for the observed transition from TTGrocks in the Archean to the GG-granitoids in post-Archean times.

  14. Oxidation of atmospheric methane in Northern European soils, comparison with other ecosystems, and uncertainties in the global terrestrial sink

    DEFF Research Database (Denmark)

    Smith, K.A.; Dobbie, K.E.; Ball, B.C.;

    2000-01-01

    , with a log-normal distribution (log-mean ˜ 1.6 kg CH4 ha-1 y-1). Conversion of natural soils to agriculture reduced oxidation rates by two-thirds -- closely similar to results reported for other regions. N inputs also decreased oxidation rates. Full recovery of rates after these disturbances takes > 100 y......This paper reports the range and statistical distribution of oxidation rates of atmospheric CH4 in soils found in Northern Europe in an international study, and compares them with published data for various other ecosystems. It reassesses the size, and the uncertainty in, the global terrestrial CH4...... sink, and examines the effect of land-use change and other factors on the oxidation rate. Only soils with a very high water table were sources of CH4; all others were sinks. Oxidation rates varied from 1 to nearly 200 µg CH4 m-2 h-1; annual rates for sites measured for =1 y were 0.1-9.1 kg CH4 ha-1 y-1...

  15. 3-D laser confocal microscopy study of the oxidation of NdFeB magnets in atmospheric conditions

    Science.gov (United States)

    Meakin, J. P.; Speight, J. D.; Sheridan, R. S.; Bradshaw, A.; Harris, I. R.; Williams, A. J.; Walton, A.

    2016-08-01

    Neodymium iron boron (NdFeB) magnets are used in a number of important applications, such as generators in gearless wind turbines, motors in electric vehicles and electronic goods (e.g.- computer hard disk drives, HDD). Hydrogen can be used as a processing gas to separate and recycle scrap sintered Nd-Fe-B magnets from end-of-life products to form a powder suitable for recycling. However, the magnets are likely to have been exposed to atmospheric conditions prior to processing, and any oxidation could lead to activation problems for the hydrogen decrepitation reaction. Many previous studies on the oxidation of NdFeB magnets have been performed at elevated temperatures; however, few studies have been formed under atmospheric conditions. In this paper a combination of 3-D laser confocal microscopy and Raman spectroscopy have been used to assess the composition, morphology and rate of oxidation/corrosion on scrap sintered NdFeB magnets. Confocal microscopy has been employed to measure the growth of surface reaction products at room temperature, immediately after exposure to air. The results showed that there was a significant height increase at the triple junctions of the Nd-rich grain boundaries. Using Raman spectroscopy, the product was shown to consist of Nd2O3 and formed only on the Nd-rich triple junctions. The diffusion coefficient of the triple junction reaction product growth at 20 °C was determined to be approximately 4 × 10-13 cm2/sec. This value is several orders of magnitude larger than values derived from the diffusion controlled oxide growth observations at elevated temperatures in the literature. This indicates that the growth of the room temperature oxidation products are likely defect enhanced processes at the NdFeB triple junctions.

  16. The effects of re-firing process under oxidizing atmosphere and temperatures on the properties of strontium aluminate phosphors

    Energy Technology Data Exchange (ETDEWEB)

    Karacaoglu, Erkul, E-mail: erkaracaoglu@gmail.com [Anadolu University, Graduate School of Sciences, Department of Materials Science and Engineering, Eskisehir (Turkey); Fosfortek Phosphor Technologies Co., Eskisehir (Turkey); Karasu, Bekir [Anadolu University, Materials Science and Engineering Department, Eskisehir (Turkey)

    2013-10-15

    Graphical abstract: The comparative emission spectra of standard and re-fired Phosphor A under oxidizing atmosphere at various temperatures. The colour of Phosphor A re-fired at higher temperatures above 900 °C shifted from yellowish-green to bluish-green in the dark. But, the bluish-green emission could only be seen when it was exposed to UV and disappeared as soon as the light source was removed. Moreover, the emission intensities decreased as the re-firing temperatures increased. This could be attributed to the oxidation of Eu{sup 2+} during the re-firing process. It is well known fact from the literature that the reduction of Eu{sup 3+} to Eu{sup 2+} in appropriate host materials needs an annealing process in a reducing atmosphere such as H{sub 2}, H{sub 2}/N{sub 2} mixture or CO. Up to now, the reduction phenomena of Eu{sup 3+} → Eu{sup 2+} in air have been found in phosphates (Ba{sub 3}(PO{sub 4}){sub 2}:Eu), sulphates (BaSO{sub 4}:Eu), borates (SrB{sub 4}O{sub 7}:Eu, SrB{sub 6}O{sub 10}:Eu and BaB{sub 8}O{sub 13}:Eu) and aluminates (Sr{sub 4}Al{sub 14}O{sub 25}:Eu). Interestingly, an apparent blue shift in the phosphorescence spectrum was observed in the samples re-fired at 1000 °C and above, indicating a minimal effect on the oxidation state or the electronic energy levels of the co-doped Dy{sup 3+} ions, which were thought to act as long-lived hole traps resulting in long afterglow. - Highlights: • This study examines the effects re-firing at oxidizing atmosphere of photoluminescence of three different commercial SrAl{sub 2}O{sub 4}:Eu{sup 2+},Dy{sup 3+}-phosphors. • All the commercial SrAl{sub 2}O{sub 4}:Eu{sup 2+},Dy{sup 3+}-phosphors completely lost their phosphorescence after being re-fired at 1300 °C. • Oxidizing environment and re-firing temperature naturally affecting the valance of Eu{sup 2+} may cause the basic lattice structure to be modified and also limit their applications at higher temperatures, such as third firing vetrosa d

  17. Determination of carbon in amorphous carbon and uranium monocarbide by oxidation with lead(IV) oxide, copper(II) oxide or barium sulfate in an inert atmosphere

    International Nuclear Information System (INIS)

    Oxidation behavior was studied on amorphous carbon and carbon in uranium monocarbide when lead(IV) oxide, copper(II) oxide and barium sulfate were used as the oxidizing fluxes in helium. The amorphous carbon and the carbon in the carbide were completely extracted with lead oxide in 5 min at 10000C and in 8 min at 700 and 5000C, respectively. Carbon in two samples was quantitatively extracted at 10000C with copper oxide in 8 and 5 min, and with barium sulfate in 7 and 5 min, respectively. The rate of extraction of carbon with copper oxide decreased with decreasing temperature. It was found that the mixing ratio of the oxidizing flux to the amorphous carbon or carbide gave effect on the recovery of carbon. The conventional capillary-trap method which is used for the determination of carbon has a disadvantage that, when carbon dioxide is caught in a cold trap (liquid nitrogen), oxygen is also trapped. This disadvantage was eliminated when a stream of helium was used in place of oxygen. Carbon in the sample can be determined with lead oxide, copper oxide or barium sulfate by extracting carbon dioxide at 10000C for 10 min. (auth.)

  18. Oxidation characteristics of nickel-base superalloys at high temperature in air and helium atmospheres

    International Nuclear Information System (INIS)

    Nickel-base superalloys are considered as materials for piping and structural materials in a very high temperature gas cooled reactor (VHTR). They are subjected to the environmental degradation caused by a continuous process for oxidation due to small amount of impurities in He coolant during long term operation. In the present study, the oxidation behaviors of several nickel-base superalloys such as Alloy-617, Haynes-214 and Haynes-230 in particular, were studied at the temperature of 900 and 1100 C degrees in air, and in the high purity He environment. Oxide layers were analyzed by SEM (Scanning Electron Microscope) and EDX (Energy Dispersive X-ray analysis). The differences in oxidation behaviors of these alloys were mainly caused by different protective oxide layers on surface. In the case of Alloy-617 and Haynes-230, Cr2O3 layer formed on the surface which is not stable at 1100 C degrees. Therefore, the weight increased significantly due to oxidation at the initial stage, which followed by a decrease due to the scaling and volatilization of Cr2O3 layer. On the other hand, since Haynes-214 has mainly Al2O3 oxide layer on surface which is more stable and has more dense structure at higher temperature, the weight gain eventually reaches to parabolic. Microstructural characteristics of internal carbides and carbide depletion zone were analyzed. With oxidation time, continuous grain boundary carbides of M23C6 type were getting thin or it disappeared partially. Especially, carbides on grain boundary disappeared entirely below oxide layer (carbide depletion zone). It was getting wide with oxidation time. For Haynes-214, the size of carbide depletion zone was smaller than other alloys because Al2O3 layer acted as a diffusion layer prevented effectively the penetration of oxygen into base metal. (authors)

  19. SCR atmosphere induced reduction of oxidized mercury over CuO-CeO2/TiO2 catalyst.

    Science.gov (United States)

    Li, Hailong; Wu, Shaokang; Wu, Chang-Yu; Wang, Jun; Li, Liqing; Shih, Kaimin

    2015-06-16

    CuO-CeO2/TiO2 (CuCeTi) catalyst synthesized by a sol-gel method was employed to investigate mercury conversion under a selective catalytic reduction (SCR) atmosphere (NO, NH3 plus O2). Neither NO nor NH3 individually exhibited an inhibitive effect on elemental mercury (Hg(0)) conversion in the presence of O2. However, Hg(0) conversion over the CuCeTi catalyst was greatly inhibited under SCR atmosphere. Systematic experiments were designed to investigate the inconsistency and explore the in-depth mechanisms. The results show that the copresence of NO and NH3 induced reduction of oxidized mercury (Hg(2+), HgO in this study), which offset the effect of catalytic Hg(0) oxidation, and hence resulted in deactivation of Hg(0) conversion. High NO and NH3 concentrations with a NO/NH3 ratio of 1.0 facilitated Hg(2+) reduction and therefore lowered Hg(0) conversion. Hg(2+) reduction over the CuCeTi catalyst was proposed to follow two possible mechanisms: (1) direct reaction, in which NO and NH3 react directly with HgO to form N2 and Hg(0); (2) indirect reaction, in which the SCR reaction consumed active surface oxygen on the CuCeTi catalyst, and reduced species on the CuCeTi catalyst surface such as Cu2O and Ce2O3 robbed oxygen from adjacent HgO. Different from the conventionally considered mechanisms, that is, competitive adsorption responsible for deactivation of Hg(0) conversion, this study reveals that oxidized mercury can transform into Hg(0) under SCR atmosphere. Such knowledge is of fundamental importance in developing efficient and economical mercury control technologies for coal-fired power plants. PMID:25961487

  20. Modelling atmospheric oxidation of 2-aminoethanol (MEA) emitted from post-combustion capture using WRF-Chem.

    Science.gov (United States)

    Karl, M; Svendby, T; Walker, S-E; Velken, A S; Castell, N; Solberg, S

    2015-09-15

    Carbon capture and storage (CCS) is a technological solution that can reduce the amount of carbon dioxide (CO2) emissions from the use of fossil fuel in power plants and other industries. A leading method today is amine based post-combustion capture, in which 2-aminoethanol (MEA) is one of the most studied absorption solvents. In this process, amines are released to the atmosphere through evaporation and entrainment from the CO2 absorber column. Modelling is a key instrument for simulating the atmospheric dispersion and chemical transformation of MEA, and for projections of ground-level air concentrations and deposition rates. In this study, the Weather Research and Forecasting model inline coupled with chemistry, WRF-Chem, was applied to quantify the impact of using a comprehensive MEA photo-oxidation sequence compared to using a simplified MEA scheme. Main discrepancies were found for iminoethanol (roughly doubled in the detailed scheme) and 2-nitro aminoethanol, short MEA-nitramine (reduced by factor of two in the detailed scheme). The study indicates that MEA emissions from a full-scale capture plant can modify regional background levels of isocyanic acid. Predicted atmospheric concentrations of isocyanic acid were however below the limit value of 1 ppbv for ambient exposure. The dependence of the formation of hazardous compounds in the OH-initiated oxidation of MEA on ambient level of nitrogen oxides (NOx) was studied in a scenario without NOx emissions from a refinery area in the vicinity of the capture plant. Hourly MEA-nitramine peak concentrations higher than 40 pg m(-3) did only occur when NOx mixing ratios were above 2 ppbv. Therefore, the spatial variability and temporal variability of levels of OH and NOx need to be taken into account in the health risk assessment. The health risk due to direct emissions of nitrosamines and nitramines from full-scale CO2 capture should be investigated in future studies. PMID:25958366

  1. SCR atmosphere induced reduction of oxidized mercury over CuO-CeO2/TiO2 catalyst.

    Science.gov (United States)

    Li, Hailong; Wu, Shaokang; Wu, Chang-Yu; Wang, Jun; Li, Liqing; Shih, Kaimin

    2015-06-16

    CuO-CeO2/TiO2 (CuCeTi) catalyst synthesized by a sol-gel method was employed to investigate mercury conversion under a selective catalytic reduction (SCR) atmosphere (NO, NH3 plus O2). Neither NO nor NH3 individually exhibited an inhibitive effect on elemental mercury (Hg(0)) conversion in the presence of O2. However, Hg(0) conversion over the CuCeTi catalyst was greatly inhibited under SCR atmosphere. Systematic experiments were designed to investigate the inconsistency and explore the in-depth mechanisms. The results show that the copresence of NO and NH3 induced reduction of oxidized mercury (Hg(2+), HgO in this study), which offset the effect of catalytic Hg(0) oxidation, and hence resulted in deactivation of Hg(0) conversion. High NO and NH3 concentrations with a NO/NH3 ratio of 1.0 facilitated Hg(2+) reduction and therefore lowered Hg(0) conversion. Hg(2+) reduction over the CuCeTi catalyst was proposed to follow two possible mechanisms: (1) direct reaction, in which NO and NH3 react directly with HgO to form N2 and Hg(0); (2) indirect reaction, in which the SCR reaction consumed active surface oxygen on the CuCeTi catalyst, and reduced species on the CuCeTi catalyst surface such as Cu2O and Ce2O3 robbed oxygen from adjacent HgO. Different from the conventionally considered mechanisms, that is, competitive adsorption responsible for deactivation of Hg(0) conversion, this study reveals that oxidized mercury can transform into Hg(0) under SCR atmosphere. Such knowledge is of fundamental importance in developing efficient and economical mercury control technologies for coal-fired power plants.

  2. Site variation in methane oxidation as affected by atmospheric deposition and type of temperate forest ecosystem

    Science.gov (United States)

    Brumme, Rainer; Borken, Werner

    1999-06-01

    Factors controlling methane oxidation were analyzed along a soil acidity gradient (pH(H2O) 3.9 to 5.2) under beech and spruce forests in Germany. Mean annual methane oxidation ranged from 0.1 to 2.5 kg CH4 ha-1 yr-1 and was correlated with base saturation (r2 = 0.88), soil pH (r2 = 0.77), total nitrogen (r2 = 0.71), amount of the organic surface horizon (r2 = 0.49) and bulk density of the mineral soil (r2 = 0.43). At lower pHs the formation of an organic surface horizon was promoted. This horizon did not have any methane oxidation capacity and acted like a gas diffusion barrier, which decreased the methane oxidation capacity of the soil. In contrast, on sites at the higher end of the pH range, higher burrowing activity of earthworms increased macroporosity and thereby gas diffusivity and methane oxidation. Gas diffusivity was also affected by litter shape: broad beech leaves reduced methane oxidation more than spruce needles. An increase in methane oxidation of most soil samples following sieving indicates that diffusion is the main limiting factor for methane oxidation. However, this "sieving effect" was less in soils with a pH below 5 than in soils with a pH above 5, which we attribute to a direct effect of soil acidity. We discuss our results using a hierarchical concept for the "short-term" and "long-term" controls on methane oxidation in forest ecosystems.

  3. Synergy of CuO and CeO2 combination for mercury oxidation under low-temperature selective catalytic reduction atmosphere

    KAUST Repository

    Li, Hailong

    2016-07-19

    Synergy for low temperature Hg0 oxidation under selective catalytic reduction (SCR) atmosphere was achieved when copper oxides and cerium oxides were combined in a CuO-CeO2/TiO2 (CuCeTi) catalyst. Hg0 oxidation efficiency as high as 99.0% was observed on the CuCeTi catalyst at 200 °C, even the gas hourly space velocity was extremely high. To analyze the synergistic effect, comparisons of catalyst performance in the presence of different SCR reaction gases were systematically conducted over CuO/TiO2 (CuTi), CeO2/TiO2 (CeTi) and CuCeTi catalysts prepared by sol-gel method. The interactions between copper oxides and cerium oxides in CuCeTi catalyst yielded more surface chemisorbed oxygen, and facilitated the conversion of gas-phase O2 to surface oxygen, which are favorable for Hg0 oxidation. Copper oxides in the combination interacted with NO forming more chemisorbed oxygen for Hg0 oxidation in the absence of gas-phase O2. Cerium oxides in the combination promoted Hg0 oxidation through enhancing the transformations of NO to NO2. In the absence of NO, NH3 exhibited no inhibitive effect on Hg0 oxidation, because enough Lewis acid sites due to the combination of copper oxides and cerium oxides scavenged the competitive adsorption between NH3 and Hg0. In the presence of NO, although NH3 lowered Hg0 oxidation rate through inducing reduction of oxidized mercury, complete recovery of Hg0 oxidation activity over the CuCeTi catalyst was quickly achieved after cutting off NH3. This study revealed the synergistic effect of the combination of copper oxides and cerium oxides on Hg0 oxidation, and explored the involved mechanisms. Such knowledge would help obtaining maximum Hg0 oxidation co-benefit from SCR units in coal-fired power plants.

  4. Biomass torrefaction characteristics in inert and oxidative atmospheres at various superficial velocities.

    Science.gov (United States)

    Chen, Wei-Hsin; Lu, Ke-Miao; Liu, Shih-Hsien; Tsai, Chi-Ming; Lee, Wen-Jhy; Lin, Ta-Chang

    2013-10-01

    The reaction characteristics of four biomass materials (i.e. oil palm fiber, coconut fiber, eucalyptus, and Cryptomeria japonica) with non-oxidative and oxidative torrefaction at various superficial velocities are investigated where nitrogen and air are used as carrier gases. Three torrefaction temperatures of 250, 300, and 350 °C are considered. At a given temperature, the solid yield of biomass is not affected by N2 superficial velocity, revealing that the thermal degradation is controlled by heat and mass transfer in biomass. Increasing air superficial velocity decreases the solid yield, especially in oil palm fiber and coconut fiber, implying that the torrefaction reaction of biomass is dominated by surface oxidation. There exists an upper limit of air superficial velocity in the decrement of solid yield, suggesting that beyond this limit the thermal degradation of biomass is no longer governed by surface oxidation, but rather is controlled by internal mass transport.

  5. Total atmospheric deposition of oxidized nitrogen in the United States Pacific Northwest for 2002

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — This spatial data set was created by the U.S. Geological Survey (USGS) to represent the amount of wet and dry deposition of oxidized nitrogen in the Pacific...

  6. Total atmospheric deposition of oxidized and reduced nitrogen in the United States Pacific Northwest for 2002

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — This spatial data set was created by the U.S. Geological Survey (USGS) to represent the amount of wet and dry deposition of oxidized and reduced nitrogen in the...

  7. Using sulfur isotope fractionation to understand the atmospheric oxidation of SO 2

    OpenAIRE

    Harris, Eliza

    2012-01-01

    Sulfate aerosol plays an important but uncertain role in cloud formation and radiative forcing of the climate, and is also important for acid deposition and human health. The oxidation of SO2 to sulfate is a key reaction in determining the impact of sulfate in the environment through its effect on aerosol size distribution and composition. This thesis presents a laboratory investigation of sulfur isotope fractionation during SO2 oxidation by the most important gas-phase and heterogeneous path...

  8. Protection of articles in oxidizing atmosphere on high-temperature heating

    International Nuclear Information System (INIS)

    Composition of the melt on the base of potassium or sodium bichromates with oxygen-containing molybdenum compounds is developed for the treatment of steel blanks to form scale-resistant oxide layer. Tubes pressed out of the blanks, covered with oxide layer, are characterized by the increased accuracy of dimensions and improved quality of the surface. Besides, application of protection layer increases the instrument endurance

  9. High-throughput processes for industrially scalable deposition of zinc oxide at atmospheric pressure

    NARCIS (Netherlands)

    Illiberi, A.; Grob, F.; Kniknie, B.; Frijters, C.; Deelen, J. van; Poodt, P.; Beckers, E.H.A.; Bolt, P.J.

    2014-01-01

    ZnO films have been grown on a moving glass substrate by high temperature (480 0C) chemical vapour deposition (CVD) and low temperature (200 0C) plasma enhanced CVD (PE-CVD) process at atmospheric pressure. Deposition rates above 7 nm/s have been achieved for substrate speeds from 20 to 500 mm/min.

  10. Nanostructured europium oxide thin films deposited by pulsed laser ablation of a metallic target in a He buffer atmosphere

    Energy Technology Data Exchange (ETDEWEB)

    Luna, H.; Franceschini, D. F.; Prioli, R.; Guimaraes, R. B.; Sanchez, C. M.; Canal, G. P.; Barbosa, M. D. L.; Galvao, R. M. O. [Instituto de Fisica, Universidade Federal do Rio de Janeiro, Cx. Postal 68528, Rio de Janeiro, RJ 21941-972 (Brazil); Instituto de Fisica, Universidade Federal Fluminense, Niteroi, RJ 24210-346 (Brazil); Departamento de Fisica, Pontificia Universidade Catolica do Rio de Janeiro, Rua Marques de Sao Vicente 225, 22453-970, Rio de Janeiro, RJ (Brazil); Instituto de Fisica, Universidade Federal Fluminense, Niteroi, RJ 24210-346 (Brazil); Centro Brasileiro de Pesquisas Fisicas, Laboratorio de Plasmas Aplicados, Rua Xavier Sigaud 150, 22290-180, Rio de Janeiro, RJ (Brazil); Instituto de Fisica, Departamento de Fisica Nuclear, Universidade de Sao Paulo, Caixa Postal 66328, 05315-970, Sao Paulo, SP (Brazil); Centro Brasileiro de Pesquisas Fisicas, Laboratorio de Plasmas Aplicados, Rua Xavier Sigaud 150, 22290-180, Rio de Janeiro, RJ (Brazil)

    2010-09-15

    Nanostrucured europium oxide and hydroxide films were obtained by pulsed Nd:YAG (532 nm) laser ablation of a europium metallic target, in the presence of a 1 mbar helium buffer atmosphere. Both the produced film and the ambient plasma were characterized. The plasma was monitored by an electrostatic probe, for plume expansion in vacuum or in the presence of the buffer atmosphere. The time evolution of the ion saturation current was obtained for several probe to substrate distances. The results show the splitting of the plume into two velocity groups, being the lower velocity profile associated with metal cluster formation within the plume. The films were obtained in the presence of helium atmosphere, for several target-to-substrate distances. They were analyzed by Rutherford backscattering spectrometry, x-ray diffraction, and atomic force microscopy, for as-deposited and 600 deg. C treated-in-air samples. The results show that the as-deposited samples are amorphous and have chemical composition compatible with europium hydroxide. The thermally treated samples show x-ray diffraction peaks of Eu{sub 2}O{sub 3}, with chemical composition showing excess oxygen. Film nanostructuring was shown to be strongly correlated with cluster formation, as shown by velocity splitting in probe current versus time plots.

  11. Mechanism and kinetic properties of OH-initiated atmospheric oxidation degradation of methamidophos in the presence of O2/NO

    Science.gov (United States)

    Shi, Xiangli; Zhang, Ruiming; Zhang, Qingzhu; Wang, Wenxing

    2016-05-01

    Methamidophos is a member of the organophosphorus insecticides. In the present work, the mechanism of the OH radical-initiated atmospheric oxidation degradation of methamidophos and the possible degradation products were investigated with the aid of quantum chemical calculations. The geometrical parameters and vibrational frequencies were calculated at the MPWB1K/6-31+G(d,p) level. The energies of all the stationary points were carried out at the MPWB1K/6-311+G(3df,2p) level of theory. The rate constants of key elementary steps involved in the OH radical-initiated atmospheric degradation of methamidophos were calculated by meaning of the canonical variation transition-state (CVT) theory with the small curvature tunneling (SCT) correction over the possible atmospheric temperature range of 273-333 K. The rate-temperature formulas were fitted for the first time. The pre-exponential factor and the activation energy were obtained. Studies show that the OH additions from the trans-positions of the NH2 and OCH3 groups, the H abstractions from the SCH3 and OCH3 groups as well as the substitution reaction resulting in the products of CH3OP(O)OHNH2 and SCH3 are thermodynamically favorable reaction pathways for the reaction of methamidophos with OH radicals due to the low barrier and strong exothermicity.

  12. Atmospheric oxygen levels, anaerobic methane oxidation, and the coupling of the global COS cycles by sulfate reduction

    Science.gov (United States)

    Wortmann, U. G.; Chernyavsky, B. M.

    2007-12-01

    Changes in the partitioning between the reduced and oxidized reservoirs of carbon and sulfur are the dominant control on atmospheric oxygen levels, and the partitioning itself depends to a large degree on microbial redox processes remineralizing organic matter (OM). However, the controls of organic matter preservation in marine sediments are one of the most complex and controversial issues in contemporary biochemistry. Knowledge how the transition from one electron acceptor to another affects OM remineralization rates is scant even for the transition from aerobic to anaerobic respiration. Much less is known about the transition from anaerobic respiration to fermentation. Although the individual pathways of methane generation are known, our understanding of the complex interactions between different bacterial groups remains limited, resulting in considerable difficulties to resolve these questions in microcosm experiments. Here we show that a dramatic drop in seawater sulfate concentrations during the Early Cretaceous (Wortmann & Chernyavsky, Nature 2007) resulted in a global breakdown of microbial sulfate reduction in the marine subsurface biosphere. This event resulted in a positive excursion of the global δ13C-value, suggesting that organic matter remineralization rates dropped by more than 50%. This implies that the methanogenic microbial community was unable to increase their metabolic rates, despite the increased supply of organic matter. the reduced availability of sulfate for anaerobic methane oxidation did not increase the flux of isotopically light carbon into the ocean/atmosphere system. We therefore speculate that the capacity of marine methanogenic ecosystems to synthesize extracellular enzymes to hydrolyze organic matter is specific to the prevailing type of organic matter. This results in a positive coupling of the metabolic activity of both ecosystems, which in turn is a necessary prerequisite to decouple reduced carbon and sulfur burial, a key

  13. Sensitivity of measured steam oxidation kinetics to atmospheric control and impurities

    Science.gov (United States)

    Sooby Wood, E.; Terrani, K. A.; Nelson, A. T.

    2016-08-01

    The most direct means of improving the ability of water cooled reactors to withstand excessive cladding oxidation during a loss of coolant accident is to either modify or replace zirconium cladding. It is important to understand what level of agreement is to be expected as a function of systematic differences in steam oxidation testing techniques and instrumentation among testing facilities. The present study was designed to assess the sensitivities of some of the current and proposed reactor cladding materials. Steam oxidation sensitivity of Zircaloy-2, FeCrAl and Mo to O2 impurities in steam were examined. It was shown that the effect of O2 impurities is negligible for the two former materials while significant in the case of Mo.

  14. An evaluation of anti-oxidative protection for cells against atmospheric pressure cold plasma treatment

    Energy Technology Data Exchange (ETDEWEB)

    Ma Ruonan; Zhang Qian [Academy for Advanced Interdisciplinary Studies, Peking University, Beijing 100871 (China); Feng Hongqing; Liang Yongdong [College of Engineering, Peking University, Beijing 100871 (China); Li Fangting [Academy for Advanced Interdisciplinary Studies, Peking University, Beijing 100871 (China); College of Physics, Peking University, Beijing 100871 (China); Zhu Weidong [Department of Applied Science and Technology, Saint Peter' s College, Jersey City, New Jersey 07306 (United States); Zhang Jue; Fang Jing [Academy for Advanced Interdisciplinary Studies, Peking University, Beijing 100871 (China); College of Engineering, Peking University, Beijing 100871 (China); Becker, Kurt H. [Department of Applied Physics, Polytechnic Institute of New York University, Brooklyn, New York 11201 (United States)

    2012-03-19

    With the development of plasma medicine, safety issues are emerging as a serious concern. In this study, both intracellular (genetic engineering) and extracellular (scavengers) measures were tested in an effort to determine the best protection for cells against plasma-induced oxidative stress. All results of immediate reactive species detection, short term survival and long term proliferation, suggest that intracellular pathways are superior in reducing oxidative stress and cell death. This work provides a potential mechanism to enhance safety and identifies precautionary measures that should be taken in future clinical applications of plasmas.

  15. Analysis of High Frequency Site-Specific Nitrogen and Oxygen Isotopic Composition of Atmospheric Nitrous Oxide at Mace Head, Ireland

    Science.gov (United States)

    McClellan, M. J.; Harris, E. J.; Olszewski, W.; Ono, S.; Prinn, R. G.

    2014-12-01

    Atmospheric nitrous oxide (N2O) significantly impacts Earth's climate due to its dual role as an inert potent greenhouse gas in the troposphere and as a reactive source of ozone-destroying nitrogen oxides in the stratosphere. However, there remain significant uncertainties in the global budget of this gas. The marked spatial divide in its reactivity means that all stages in the N2O life cycle—emission, transport, and destruction—must be examined to understand the overall effect of N2O on climate. Source and sink processes of N2O lead to varying concentrations of N2O isotopologues (14N14N16O, 14N15N16O, 15N14N16O, and 14N14N18O being measured) due to preferential isotopic production and elimination in different environments. Estimation of source and sink fluxes can be improved by combining isotopically resolved N2O observations with simulations using a chemical transport model with reanalysis meteorology and treatments of isotopic signatures of specific surface sources and stratospheric intrusions. We present the first few months of site-specific nitrogen and oxygen isotopic composition data from the Stheno-TILDAS instrument (Harris et al, 2013) at Mace Head, Ireland and compare these to results from MOZART-4 (Model for Ozone and Related Chemical Tracers, version 4) chemical transport model runs including N2O isotopic fractionation processes and reanalysis meterological fields (NCEP/NCAR, MERRA, and GEOS-5). This study forms the basis for future inverse modeling experiments that will improve the accuracy of isotopically differentiated N2O emission and loss estimates. Ref: Harris, E., D. Nelson, W. Olszewski, M. Zahniser, K. Potter, B. McManus, A. Whitehill, R. Prinn, and S. Ono, Development of a spectroscopic technique for continuous online monitoring of oxygen and site-specific nitrogen isotopic composition of atmospheric nitrous oxide, Analytical Chemistry, 2013; DOI: 10.1021/ac403606u.

  16. Non-thermal atmospheric pressure HF plasma source: generation of nitric oxide and ozone for bio-medical applications

    Energy Technology Data Exchange (ETDEWEB)

    Kuehn, S; Gesche, R [Ferdinand-Braun-Institut (FBH), Gustav-Kirchhoff-Str. 4, 12489 Berlin (Germany); Bibinov, N; Awakowicz, P [Institute for Electrical Engineering and Plasma Technology, Ruhr-Universitaet Bochum, Universitaetsstr. 150, 44801 Bochum (Germany)], E-mail: Silvio.Kuehn@fbh-berlin.de, E-mail: Nikita.Bibinov@rub.de

    2010-01-15

    A new miniature high-frequency (HF) plasma source intended for bio-medical applications is studied using nitrogen/oxygen mixture at atmospheric pressure. This plasma source can be used as an element of a plasma source array for applications in dermatology and surgery. Nitric oxide and ozone which are produced in this plasma source are well-known agents for proliferation of the cells, inhalation therapy for newborn infants, disinfection of wounds and blood ozonation. Using optical emission spectroscopy, microphotography and numerical simulation, the gas temperature in the active plasma region and plasma parameters (electron density and electron distribution function) are determined for varied nitrogen/oxygen flows. The influence of the gas flows on the plasma conditions is studied. Ozone and nitric oxide concentrations in the effluent of the plasma source are measured using absorption spectroscopy and electro-chemical NO-detector at variable gas flows. Correlations between plasma parameters and concentrations of the particles in the effluent of the plasma source are discussed. By varying the gas flows, the HF plasma source can be optimized for nitric oxide or ozone production. Maximum concentrations of 2750 ppm and 400 ppm of NO and O{sub 3}, correspondingly, are generated.

  17. Non-thermal atmospheric pressure HF plasma source: generation of nitric oxide and ozone for bio-medical applications

    International Nuclear Information System (INIS)

    A new miniature high-frequency (HF) plasma source intended for bio-medical applications is studied using nitrogen/oxygen mixture at atmospheric pressure. This plasma source can be used as an element of a plasma source array for applications in dermatology and surgery. Nitric oxide and ozone which are produced in this plasma source are well-known agents for proliferation of the cells, inhalation therapy for newborn infants, disinfection of wounds and blood ozonation. Using optical emission spectroscopy, microphotography and numerical simulation, the gas temperature in the active plasma region and plasma parameters (electron density and electron distribution function) are determined for varied nitrogen/oxygen flows. The influence of the gas flows on the plasma conditions is studied. Ozone and nitric oxide concentrations in the effluent of the plasma source are measured using absorption spectroscopy and electro-chemical NO-detector at variable gas flows. Correlations between plasma parameters and concentrations of the particles in the effluent of the plasma source are discussed. By varying the gas flows, the HF plasma source can be optimized for nitric oxide or ozone production. Maximum concentrations of 2750 ppm and 400 ppm of NO and O3, correspondingly, are generated.

  18. Nitrous oxide in the Schelde estuary: production by nitrification and emission to the atmosphere

    NARCIS (Netherlands)

    De Wilde, H.; De Bie, M.J.M.

    2000-01-01

    Concentrations of nitrous oxide (N2O), oxygen, nitrate, and ammonium, as well as nitrification activity were determined along the salinity gradient of the Schelde Estuary, Northwest Europe, in October 1993, March 1994, and July 1996, The entire estuary was always supersaturated with N2O. Concentrati

  19. Oxidative stress on plasmid DNA induced by inhalable particles in the urban atmosphere

    Institute of Scientific and Technical Information of China (English)

    SHI Zongbo; SHAO Longyi; T. P. Jones; A. G. Whittaker; R. J. Richards; ZHANG Pengfei

    2004-01-01

    Plasmid DNA assay is a newly-developed in vitro method to investigate bioreactivity of particles. In this paper, this method was used to study the bioreactivity of PM10 (particulate matter with aerodynamic diameter of less than 10цm) and PM2.5 (particulate matter with aerodynamic diameter of less than 2.5 цm). Samples and dust storm particles were collected in 2001 in an urban area, a satellite city and a clean air area in Beijing. A big difference was found for oxidative DNA stress induced by different particulate matter (PM) samples, with the TM50 (particle mass causing 50% damage to DNA) values varying by a factor over 10. This was closely dependent on the sizes of particles as well as the variation in relative proportion of mineral matter. PM2.5 samples generally impose larger oxidative stress on plasmid DNA than PM10 samples. Airborne particles collected during dust storm episodes, usually with a higher proportion of mineral matter, have a much lower oxidative capacity than those collected during non-dust storm episodes. PM samples and their water-soluble fractions usually have similar bioreactivities, demonstrating that oxidative capacity of Beijing airborne particles is mainly sourced from their water-soluble fractions.

  20. Different Atmospheric Methane-Oxidizing Communities in European Beech and Norway Spruce Soils▿ †

    OpenAIRE

    Degelmann, Daniela M.; Borken, Werner; Drake, Harold L; Kolb, Steffen

    2010-01-01

    Norway spruce (Picea abies) forests exhibit lower annual atmospheric methane consumption rates than do European beech (Fagus sylvatica) forests. In the current study, pmoA (encoding a subunit of membrane-bound CH4 monooxygenase) genes from three temperate forest ecosystems with both beech and spruce stands were analyzed to assess the potential effect of tree species on methanotrophic communities. A pmoA sequence difference of 7% at the derived protein level correlated with the species-level d...

  1. Preparation of Aluminium Oxynitride by Carbothermal Reduction of Aluminium Oxide in a Flowing N2 Atmosphere

    Institute of Scientific and Technical Information of China (English)

    LIYa-wei; YUANRun-zhang; 等

    1996-01-01

    Carbothermal reduction of alumina into aluminium oxynitride(AlON) spinel in a flowing nitrogen atmosphere was studied.The effects of Al2O3/C ratio temperature,soaking time,heating rate molding pressure of samples,and nitrogen flow rate on reactions were investigated.Then the stability of AlON was elucidated and AlON wa confirmed as an intermediate compound in reduction of alumina.

  2. Effect of surface oxide film and atmosphere on microwave heating of compacted copper powder

    International Nuclear Information System (INIS)

    The microwave irradiation was performed using a compacted Cu powder under different oxygen partial pressures. After reaching about 600 K, an abrupt temperature rise and drop occurred. The abrupt temperature drop is caused by both sintering of Cu powder particles and growing of surface oxide film. The magnitude of the abrupt temperature drop decreased with increasing oxygen partial pressure. The temperature then remained constant (steady state), gradually increased or exhibited a secondary significant increase. The magnitude of the temperature rise after abrupt temperature drop increased with increasing oxygen partial pressure. The microwave heating behavior of the compacted Cu powder depended on the type and thickness of the surface oxide film and also on the type and volume fraction of the gas occupying the vacant spaces between the Cu powder particles.

  3. Influence of Inert and Oxidizing Atmospheres on the Physical and Optical Properties of Luminescent Carbon Dots Prepared through Pyrolysis of a Model Molecule.

    Science.gov (United States)

    Machado, Cláudia Emanuele; Tartuci, Letícia Gazola; de Fátima Gorgulho, Honória; de Oliveira, Luiz Fernando Cappa; Bettini, Jefferson; Pereira dos Santos, Daniela; Ferrari, Jefferson Luis; Schiavon, Marco Antônio

    2016-03-18

    This work used L-tartaric acid as a model molecule to evaluate how the use of inert and oxidizing atmospheres during pyrolysis affected the physical and optical properties of the resulting carbon dots (CDs). Pyrolysis revealed to be a simple procedure that afforded CDs in a single step, dismissed the addition of organic solvents, and involved only one extraction stage that employed water. By X-ray diffraction a dependency between the structure of the CDs and the atmosphere (oxidizing or inert) used during the pyrolysis was found. Potentiometric titration demonstrated that the CDs were largely soluble in water; it also aided characterization of the various groups that contained sp(3) -hybridized carbon atoms on the surface of the dots. Raman spectroscopy suggested that different amounts of sp(2)- and sp(3)-hybridized carbon atoms emerged on the CDs depending on the pyrolysis atmosphere. In conclusion, the pyrolysis atmosphere influenced the physical properties, such as the composition and the final structure.

  4. Mercury oxidation via chlorine, bromine, and iodine under atmospheric conditions: thermochemistry and kinetics.

    Science.gov (United States)

    Auzmendi-Murua, Itsaso; Castillo, Álvaro; Bozzelli, Joseph W

    2014-04-24

    Emissions of gaseous mercury from combustion sources are the major source of Hg in the atmosphere and in environmental waters and soils. Reactions of Hg(o)(g) with halogens are of interest because they relate to mercury and ozone depletion events in the Antarctic and Arctic early spring ozone hole events, and the formation of Hg-halides (HgX2) is a method for removal of mercury from power generation systems. Thermochemistry and kinetics from published theoretical and experimental studies in the literature and from computational chemistry are utilized to compile a mechanism of the reactions considered as contributors to the formation of HgX2 (X = Cl, Br, I) to understand the reaction paths and mechanisms under atmospheric conditions. Elementary reaction mechanisms are assembled and evaluated using thermochemistry for all species and microscopic reversibility for all reactions. Temperature and pressure dependence is determined with quantum Rice Ramsperger Kassel (RRK) analysis for k(E) and master equation analysis for fall-off. We find that reactions of mercury with a small fraction of the reactor surface or initiation by low concentrations of halogen atoms is needed to explain the experimental conversion of Hg to HgX2 in the gas phase. The models do not replicate data from experiments that do not explicitly provide an atom source. The Hg insertion reaction into X2 (Hg + X2 → HgX2) that has been reported is further studied, and we find agreement with studies that report high barriers. The high barriers prevent this insertion path from explaining the experimental data on HgX2 formation and Hg conversion under atmospheric conditions. Mechanism studies with low initial concentrations of halogen radicals show significant conversion of Hg under the experimental conditions. PMID:24661061

  5. Microkinetics of H2S Removal by Zinc Oxide in the Presence of Moist Gas Atmosphere

    Institute of Scientific and Technical Information of China (English)

    Huiling Fan; Chunhu Li; Hanxian Guo; Kechang Xie

    2003-01-01

    The microkinetics of H2S removal by ZnO desulfurization in H2O-CO2-N2, H2O-CO-N2 andH2O-O2-N2 gas mixtures was studied by thermogravimetric analysis. Experiments were carried out with100 120 mesh ZnO powder at temperatures from 473 K to 563 K. The results show that the kineticbehaviors of desulfurization could all be described by an improved shrinking-core model. The activationenergies of the reaction and the diffusion in different gas atmospheres were estimated.

  6. Atmospheric oxidation of sulphur dioxide in water droplets in presence of ammonia

    Energy Technology Data Exchange (ETDEWEB)

    McKay, H.A.C.

    1971-01-01

    The kinetics of the conversion of ammonia and sulphur dioxide to ammonium sulphate in water droplets in the atmosphere in the absence of metal ion catalysts has been reconsidered. It is concluded that the reaction is an order of magnitude faster than earlier work suggested, and that lowering the temperature increases the rate by a large factor. In a cloud or a thick mist appreciable amounts of ammonium sulphate may be formed in a few minutes; nevertheless a substantial proportion of unreacted ammonia may sometimes persist for hours, even though excess sulphur dioxide is present and the initial reaction is fast.

  7. Theoretical perspectives on the mechanism and kinetics of the OH radical-initiated gas-phase oxidation of PCB126 in the atmosphere

    Energy Technology Data Exchange (ETDEWEB)

    Dang, Juan; Shi, Xiangli; Zhang, Qingzhu, E-mail: zqz@sdu.edu.cn; Wang, Wenxing

    2015-06-01

    Polychlorinated biphenyls (PCBs) primarily exist in the gas phase in air and may undergo atmospheric oxidation degradations, particularly the oxidation reaction initiated by OH radicals. In this work, the mechanism of the OH radical-initiated atmospheric oxidation of the most toxic PCB congener 3,3′,4,4′,5-pentachlorobiphenyl (PCB126) was investigated by using quantum chemistry methods. The rate constants of the crucial elementary reactions were estimated by the Rice–Ramsperger–Kassel–Marcus (RRKM) theory. The oxidation products of the reaction of PCB126 with OH radicals include 3,3′,4,4′,5-pentachlorobiphenyl-ols, chlorophenols, 2,3,4,7,8-pentachlorodibenzofuran, 2,3,4,6,7-pentachlorodibenzofuran, dialdehydes, 3,3′,4,4′,5-pentachloro-5′-nitro-biphenyl, and 4,5-dichloro-2-nitrophenol. Particularly, the formation of polychlorinated dibenzofurans (PCDFs) from the atmospheric oxidation of PCBs is revealed for the first time. The overall rate constant of the OH addition reaction is 2.52 × 10{sup −13} cm{sup 3} molecule{sup −1} s{sup −1} at 298 K and 1 atm. The atmospheric lifetime of PCB126 determined by OH radicals is about 47.08 days which indicates that PCB126 can be transported long distances from local to global scales. - Highlights: • A comprehensive mechanism of OH-initiated oxidation of PCB126 was investigated. • The formation of PCDFs from the oxidation of PCBs is determined for the first time. • The rate constants for key elementary reactions were estimated by the RRKM theory. • The atmospheric lifetime of PCB126 determined by OH radicals is about 47.08 days.

  8. Advanced Gasification By-Product Utilization

    Energy Technology Data Exchange (ETDEWEB)

    Rodney Andrews; Aurora Rubel; Jack Groppo; Brock Marrs; Ari Geertsema; Frank Huggins; M. Mercedes Maroto-Valer; Brandie M. Markley; Zhe Lu; Harold Schobert

    2006-08-31

    With the passing of legislation designed to permanently cap and reduce mercury emissions from coal-fired utilities, it is more important than ever to develop and improve upon methods of controlling mercury emissions. One promising technique is carbon sorbent injection into the flue gas of the coal-fired power plant. Currently, this technology is very expensive as costly commercially activated carbons are used as sorbents. There is also a significant lack of understanding of the interaction between mercury vapor and the carbon sorbent, which adds to the difficulty of predicting the amount of sorbent needed for specific plant configurations. Due to its inherent porosity and adsorption properties as well as on-site availability, carbons derived from gasifiers are potential mercury sorbent candidates. Furthermore, because of the increasing restricted use of landfilling, the coal industry is very interested in finding uses for these materials as an alternative to the current disposal practice. The results of laboratory investigations and supporting technical assessments conducted under DOE Subcontract No. DE-FG26-03NT41795 are reported. This contract was with the University of Kentucky Research Foundation, which supports work with the University of Kentucky Center for Applied Energy Research and The Pennsylvania State University Energy Institute. The worked described was part of a project entitled ''Advanced Gasification By-Product Utilization''. This work involved the development of technologies for the separation and characterization of coal gasification slags from operating gasification units, activation of these materials to increase mercury and nitrogen oxide capture efficiency, assessment of these materials as sorbents for mercury and nitrogen oxides, assessment of the potential for leaching of Hg captured by the carbons, analysis of the slags for cement applications, and characterization of these materials for use as polymer fillers. The

  9. Surface reactivity and oxygen migration in amorphous indium-gallium-zinc oxide films annealed in humid atmosphere

    International Nuclear Information System (INIS)

    An isotope tracer study, i.e., 18O/16O exchange using 18O2 and H218O, was performed to determine how post-deposition annealing (PDA) affected surface reactivity and oxygen diffusivity of amorphous indium–gallium–zinc oxide (a-IGZO) films. The oxygen tracer diffusivity was very high in the bulk even at low temperatures, e.g., 200 °C, regardless of PDA and exchange conditions. In contrast, the isotope exchange rate, dominated by surface reactivity, was much lower for 18O2 than for H218O. PDA in a humid atmosphere at 400 °C further suppressed the reactivity of O2 at the a-IGZO film surface, which is attributable to –OH-terminated surface formation

  10. Oxidation of siloxanes during biogas combustion and nanotoxicity of Si-based particles released to the atmosphere.

    Science.gov (United States)

    Tansel, Berrin; Surita, Sharon C

    2014-01-01

    Siloxanes have been detected in the biogas produced at municipal solid waste landfills and wastewater treatment plants. When oxidized, siloxanes are converted to silicon oxides. The objectives of this study were to evaluate the transformation of siloxanes and potential nanotoxicity of Si-based particles released to the atmosphere from the gas engines which utilize biogas. Data available from nanotoxicity studies were used to assess the potential health risks associated with the inhalation exposure to Si-based nanoparticles. Silicon dioxide formed from siloxanes can range from 5 nm to about 100 nm in diameter depending on the combustion temperature and particle clustering characteristics. In general, silicon dioxide particles formed during from combustion process are typically 40-70 nm in diameter and can be described as fibrous dusts and as carcinogenic, mutagenic, astmagenic or reproductive toxic (CMAR) nanoparticles. Nanoparticles deposit in the upper respiratory system, conducting airways, and the alveoli. Size ranges between 5 and 50 nm show effective deposition in the alveoli where toxic effects are higher. In this study the quantities for the SiO₂ formed and release during combustion of biogas were estimated based on biogas utilization characteristics (gas compositions, temperature). The exposure to Si-based particles and potential effects in humans were analyzed in relation to their particle size, release rates and availability in the atmosphere. The analyses showed that about 54.5 and 73 kg/yr of SiO₂ can be released during combustion of biogas containing D4 and D5 at 14.1 mg/m(3) (1 ppm) and 15.1 mg/m(3) (1ppm), respectively, per MW energy yield.

  11. Laboratory Studies of Processing of Carbonaceous Aerosols by Atmospheric Oxidants/Hygroscopicity and CCN Activity of Secondary & Processed Primary Organic Aerosols

    Energy Technology Data Exchange (ETDEWEB)

    Ziemann, P.J.; Arey, J.; Atkinson, R.; Kreidenweis, S.M.; Petters, M.D.

    2012-06-13

    The atmosphere is composed of a complex mixture of gases and suspended microscopic aerosol particles. The ability of these particles to take up water (hygroscopicity) and to act as nuclei for cloud droplet formation significantly impacts aerosol light scattering and absorption, and cloud formation, thereby influencing air quality, visibility, and climate in important ways. A substantial, yet poorly characterized component of the atmospheric aerosol is organic matter. Its major sources are direct emissions from combustion processes, which are referred to as primary organic aerosol (POA), or in situ processes in which volatile organic compounds (VOCs) are oxidized in the atmosphere to low volatility reaction products that subsequent condense to form particles that are referred to as secondary organic aerosol (SOA). POA and VOCs are emitted to the atmosphere from both anthropogenic and natural (biogenic) sources. The overall goal of this experimental research project was to conduct laboratory studies under simulated atmospheric conditions to investigate the effects of the chemical composition of organic aerosol particles on their hygroscopicity and cloud condensation nucleation (CCN) activity, in order to develop quantitative relationships that could be used to more accurately incorporate aerosol-cloud interactions into regional and global atmospheric models. More specifically, the project aimed to determine the products, mechanisms, and rates of chemical reactions involved in the processing of organic aerosol particles by atmospheric oxidants and to investigate the relationships between the chemical composition of organic particles (as represented by molecule sizes and the specific functional groups that are present) and the hygroscopicity and CCN activity of oxidized POA and SOA formed from the oxidation of the major classes of anthropogenic and biogenic VOCs that are emitted to the atmosphere, as well as model hydrocarbons. The general approach for this project was

  12. Plant species diversity affects soil-atmosphere fluxes of methane and nitrous oxide.

    Science.gov (United States)

    Niklaus, Pascal A; Le Roux, Xavier; Poly, Franck; Buchmann, Nina; Scherer-Lorenzen, Michael; Weigelt, Alexandra; Barnard, Romain L

    2016-07-01

    Plant diversity effects on ecosystem functioning can potentially interact with global climate by altering fluxes of the radiatively active trace gases nitrous oxide (N2O) and methane (CH4). We studied the effects of grassland species richness (1-16) in combination with application of fertilizer (nitrogen:phosphorus:potassium = 100:43.6:83 kg ha(-1) a(-1)) on N2O and CH4 fluxes in a long-term field experiment. Soil N2O emissions, measured over 2 years using static chambers, decreased with species richness unless fertilizer was added. N2O emissions increased with fertilization and the fraction of legumes in plant communities. Soil CH4 uptake, a process driven by methanotrophic bacteria, decreased with plant species numbers, irrespective of fertilization. Using structural equation models, we related trace gas fluxes to soil moisture, soil inorganic N concentrations, nitrifying and denitrifying enzyme activity, and the abundance of ammonia oxidizers, nitrite oxidizers, and denitrifiers (quantified by real-time PCR of gene fragments amplified from microbial DNA in soil). These analyses indicated that plant species richness increased soil moisture, which in turn increased N cycling-related activities. Enhanced N cycling increased N2O emission and soil CH4 uptake, with the latter possibly caused by removal of inhibitory ammonium by nitrification. The moisture-related indirect effects were surpassed by direct, moisture-independent effects opposite in direction. Microbial gene abundances responded positively to fertilizer but not to plant species richness. The response patterns we found were statistically robust and highlight the potential of plant biodiversity to interact with climatic change through mechanisms unrelated to carbon storage and associated carbon dioxide removal. PMID:27038993

  13. Determination of nitrogen in uranium-plutonium mixed oxide fuel by gas chromatography after fusion in an inert gas atmosphere

    International Nuclear Information System (INIS)

    A gas chromatographic technique has been developed for the determination of nitrogen in uranium-plutonium mixed oxide fuel after fusion in an inert gas atmosphere. When the sample and pure iron powder in a graphite crucible were heated to approximately 2500C by a resistance heating furnace, a large amount of carbon monoxide was evolved with a small amount of nitrogen and hydrogen. A gas chromatograph equipped with a pre-cut system was used for the separation of nitrogen from the carbon monoxide. Nitrogen separated by the gas chromatograph was determined by means of a thermal conductivity detector. Only 100mg of the sample was used, and the analysis requires about 10min. No specific skills for glove-box work are necessary. The relative standard deviation and detection limit (3σ-criterion) were less than 5% and 9μgg-1, respectively. The present method is not only applicable to the analysis of research samples but also to the quality control of uranium-plutonium mixed oxide fuel production lines

  14. Electrochromic properties of novel atmospheric pressure plasma jet-synthesized-organotungsten oxide films for flexible electrochromic devices

    Energy Technology Data Exchange (ETDEWEB)

    Lin, Y.-S.; Wu, S.-S.; Tsai, T.-H. [Department of Chemical Engineering, Feng Chia University, No.100, Wenhwa Road, Seatwen, Taichung, Taiwan 407 (China)

    2010-12-15

    An investigation was conducted in electrochromic performance of organotungsten oxide WO{sub x}C{sub y} films deposited onto 40 {omega}/square flexible PET (polyethylene terephthalate)/ITO (indium tin oxide) substrates using atmospheric pressure plasma jet (APPJ) at various precursor injection angles. A precursor [tungsten carbonyl, W(CO){sub 6};TC] vapor, carried by argon gas, was injected into air plasma torch. The APPJ-synthesized WO{sub x}C{sub y} films were proven to offer extraordinary electrochromic performance. Cyclic voltammetry (CV) switching measurements indicated that only low driving voltages from -1 to +1 V are needed to offer reversible Li{sup +} ion intercalation and de-intercalation in a 1 M LiClO{sub 4}-propylene carbonate (PC) electrolyte. Light modulation with up to 72.5% transmittance variation, optical density change of 0.84 and coloration efficiency of 49.6 cm{sup 2}/mC at a wavelength of 797.6 nm after 200 cycles of Li{sup +} ion intercalation and deintercalation were obtained. (author)

  15. Impact of Atmospheric Microparticles on the Development of Oxidative Stress in Healthy City/Industrial Seaport Residents

    Directory of Open Access Journals (Sweden)

    Kirill Golokhvast

    2015-01-01

    Full Text Available Atmospheric microsized particles producing reactive oxygen species can pose a serious health risk for city residents. We studied the responses of organisms to microparticles in 255 healthy volunteers living in areas with different levels of microparticle air pollution. We analyzed the distribution of microparticles in snow samples by size and content. ELISA and flow cytometry methods were employed to determine the parameters of the thiol-disulfide metabolism, peroxidation and antioxidant, genotoxicity, and energy state of the leukocytes. We found that, in the park areas, microparticles with a size of 800 μm or more were predominant (96%, while in the industrial areas, they tended to be less than 50 μm (93%, including size 200–300 nm (7%. In the industrial areas, we determined the oxidative modification of proteins (21% compared to the park areas, p≤0.05 and DNA (12%, p≤0.05, as well as changes in leukocytes’ energy potential (53%, p≤0.05. An increase in total antioxidant activity (82%, p≤0.01 and thiol-disulfide system response (thioredoxin increasing by 33%, p≤0.01; glutathione, 30%, p≤0.01 with stable reductases levels maintains a balance of peroxidation-antioxidant processes, protecting cellular and subcellular structures from significant oxidative damage.

  16. Gas chromatographic vapor pressure determination of atmospherically relevant oxidation products of β-caryophyllene and α-pinene

    Science.gov (United States)

    Hartonen, Kari; Parshintsev, Jevgeni; Vilja, Vesa-Pekka; Tiala, Heidi; Knuuti, Sinivuokko; Lai, Ching Kwan; Riekkola, Marja-Liisa

    2013-12-01

    Vapor pressures (subcooled liquid, pliquid) of atmospherically relevant oxidation products of β-caryophyllene (β-caryophyllene aldehyde 0.18 ± 0.03 Pa and β-nocaryophyllene aldehyde 0.17 ± 0.03 Pa), and α-pinene (pinonaldehyde 16.8 ± 0.20 Pa, cis-pinic acid 0.12 ± 0.06 Pa, and cis-pinonic acid 0.99 ± 0.19 Pa) at 298 K were obtained by gas chromatography with flame ionization detection (FID) and mass spectrometric (MS) detection. The effects of stationary phase polarity and column film thickness on the vapor pressure values were investigated. Increase in stationary phase polarity provided smaller values, while increase in film thickness gave slightly higher values. Values for vapor pressure were at least two orders of magnitude lower when obtained by a method utilizing vaporization enthalpy (determined by gas chromatography-mass spectrometry) than by retention index method. Finally, the results were compared with values calculated by group contribution theory. For the β-caryophyllene oxidation products, the values measured by gas chromatography were slightly lower than those obtained by theoretical calculations. The opposite trend was observed for the α-pinene oxidation products. The methods based on gas chromatography are concluded to be highly useful for the determination of vapor pressures of semi-volatile compounds. Except for the most polar pinic and pinonic acids, differences between vapor pressure values obtained by GC-FID and GC-MS were small. Since GC-MS provides structural information simultaneously, the use of GC-MS is recommended.

  17. Synthesis and modeling of uniform complex metal oxides by close-proximity atmospheric pressure chemical vapor deposition.

    Science.gov (United States)

    Hoye, Robert L Z; Muñoz-Rojas, David; Musselman, Kevin P; Vaynzof, Yana; MacManus-Driscoll, Judith L

    2015-05-27

    A close-proximity atmospheric pressure chemical vapor deposition (AP-CVD) reactor is developed for synthesizing high quality multicomponent metal oxides for electronics. This combines the advantages of a mechanically controllable substrate-manifold spacing and vertical gas flows. As a result, our AP-CVD reactor can rapidly grow uniform crystalline films on a variety of substrate types at low temperatures without requiring plasma enhancements or low pressures. To demonstrate this, we take the zinc magnesium oxide (Zn(1-x)Mg(x)O) system as an example. By introducing the precursor gases vertically and uniformly to the substrate across the gas manifold, we show that films can be produced with only 3% variation in thickness over a 375 mm(2) deposition area. These thicknesses are significantly more uniform than for films from previous AP-CVD reactors. Our films are also compact, pinhole-free, and have a thickness that is linearly controllable by the number of oscillations of the substrate beneath the gas manifold. Using photoluminescence and X-ray diffraction measurements, we show that for Mg contents below 46 at. %, single phase Zn(1-x)Mg(x)O was produced. To further optimize the growth conditions, we developed a model relating the composition of a ternary oxide with the bubbling rates through the metal precursors. We fitted this model to the X-ray photoelectron spectroscopy measured compositions with an error of Δx = 0.0005. This model showed that the incorporation of Mg into ZnO can be maximized by using the maximum bubbling rate through the Mg precursor for each bubbling rate ratio. When applied to poly(3-hexylthiophene-2,5-diyl) hybrid solar cells, our films yielded an open-circuit voltage increase of over 100% by controlling the Mg content. Such films were deposited in short times (under 2 min over 4 cm(2)). PMID:25939729

  18. Were ancient granitoid compositions influenced by contemporaneous atmospheric and hydrosphere oxidation states?

    Science.gov (United States)

    Jagoutz, O. E.

    2013-12-01

    A fundamental shift in the nature of granitoids occurs at approximately the Archean-Proterozoic boundary. Archean crust is dominated Na-rich tonalite-trondhjemite-granodiorites (TTGs), whereas post-Archean granitoids are characterized by K-rich granodiorite-granite (GG). Due to the HREE depletion commonly found in TTGs indicating the presence of residual garnet, many researchers have proposed that the difference in Na/K is related to the deeper melting depth of the TTG parental liquids. Here I present a compilation of the relevant experimental data, documenting that no correlation exists between the Na/K of derivative felsic liquids and the pressure of partial melting/fractional crystallization. Instead, the Na/K ratio of the felsic liquid best correlates with the Na/K ratio of the source. This implies that in Archean time the source material of TTG rocks must have been Na/K enriched relative to the modern. Modern granitoids are dominantly formed in a supra subduction zone environment, where a feedback loop exists between subducted materials (oceanic crust and sediments) and arc magmatism. Sea-floor weathering and the Na/K of the altered oceanic crust strongly depends on f(O2) conditions during alteration, which likely changed with earth history. During alteration under oxidized condition K2O is fixated due to the formation of celadonite (K-Mica), wheres during anoxic condition saponite (Na-Smectite) is the stable alteration mineral. I propose that the rise of oxygen at 2600-2400 Ma triggered associated changes in f(O2) seafloor alteration conditions. The change in the dominant seafloor alteration mineral from reduced to oxidized causes a change in the nature of the arc magma source and provides a possible explanation for the observed transition from TTGrocks in the Archean to the GG-granitoids in post-Archean times.

  19. ADVANCED GASIFICATION BY-PRODUCT UTILIZATION

    Energy Technology Data Exchange (ETDEWEB)

    Rodney Andrews; Aurora Rubel; Jack Groppo; Ari Geertsema; M. Mercedes Maroto-Valer; Zhe Lu; Harold Schobert

    2005-04-01

    The results of laboratory investigations and supporting technical assessments conducted under DOE Subcontract No. DE-FG26-03NT41795 are reported for the period September 1, 2003 to August 31, 2004. This contract is with the University of Kentucky Research Foundation, which supports work with the University of Kentucky Center for Applied Energy Research and The Pennsylvania State University Energy Institute. The worked described was part of a project entitled ''Advanced Gasification By-Product Utilization''. This work involves the development of technologies for the separation and characterization of coal gasification slags from operating gasification units, activation of these materials to increase mercury and nitrogen oxide capture efficiency, assessment of these materials as sorbents for mercury and nitrogen oxides, and characterization of these materials for use as polymer fillers.

  20. Soil-Atmosphere Exchange of Nitrous Oxide, Nitric Oxide, Methane, and Carbon Dioxide in Logged and Undisturbed Forest in the Tapajos National Forest, Brazil

    Science.gov (United States)

    Keller, M.; Varner, R. K.; Dias, J. D.; Silva, H.; Crill, P. M.; de Oliveira, R. C.; Asner, G. P.

    2004-12-01

    Selective logging is an extensive land use in the Brazilian Amazon region. We studied the soil-atmosphere fluxes of nitrous oxide (N2O), nitric oxide (NO), methane (CH4), and carbon dioxide (CO2) on two soil types (clay Oxisol and sandy loam Ultisol) over two years (2000-2001) in both undisturbed forest and forest recently logged using reduced impact forest management in the Tapajos National Forest, near Santarem, Para, Brazil. In undisturbed forest, annual soil-atmosphere fluxes of N2O (mean +/- standard error) were 7.9 +/- 0.7 and 7.0 +/- 0.6 ng N cm-2 h-1 for the Oxisol and 1.7 +/- 0.1 and 1.6 +/- 0.3 ng N cm-2 h-1 for the Ultisol for 2000 and 2001 respectively. The annual fluxes of NO from undisturbed forest soil in 2001 was 9.0 +/- 2.8 ng N cm-2 h-1 for the Oxisol and 8.8 +/- 5.0 ng N cm-2 h-1 for the Ultisol. Consumption of CH4 from the atmosphere dominated over production on undisturbed forest soils. Fluxes averaged -0.3 +/- 0.2 and -0.1 +/- 0.9 mg CH4 m-2 d-1 on the Oxisol and -1.0 +/- 0.2 and -0.9 +/- 0.3 mg CH4 m-2 d-1 on the Ultisol for years 2000 and 2001. For CO2 in 2001, the annual fluxes averaged 3.6 +/- 0.4 μ mol m-2 d-1 on the Oxisol and 4.9 +/- 1.1 μ mol m-2 d-1 on the Ultisol. We measured fluxes over one year each from two recently logged forests on the Oxisol in 2000 and on the Ultisol in 2001. Sampling in logged areas was stratified from greatest to least ground disturbance covering log decks, skid trails, tree-fall gaps, and forest matrix. Areas of strong soil compaction, especially the skid trails and logging decks were prone to significantly greater emissions of N2O, NO, and especially CH4. In the case of CH4, estimated annual emissions from decks reached extremely high rates of 531 +/- 419 and 98 +/- 41 mg CH4 m-2 d-1, for Oxisol and Ultisol respectively, comparable to wetland emissions in the region. We calculated excess fluxes from logged areas by subtraction of a background forest flux and adjusted these fluxes for the proportional

  1. The influence of atmospheric species on the degradation of aluminum doped zinc oxide and Cu(In,Ga)Se2 solar cells

    NARCIS (Netherlands)

    Theelen, M.J.; Foster, C.; Dasgupta, S.; Vroon, Z.A.E.P.; Barreau, N.; Zeman, M.

    2014-01-01

    Aluminum doped zinc oxide (ZnO:Al) layers were exposed to the atmospheric gases carbondioxide (CO2), oxygen (O2), nitrogen (N2) and air as well as liquid H2O purged with these gases, in order to investigate the chemical degradation behavior of these layers. The samples were analyzed by electrical, c

  2. Atmospheric methane removal by methane-oxidizing bacteria immobilized on porous building materials.

    Science.gov (United States)

    Ganendra, Giovanni; De Muynck, Willem; Ho, Adrian; Hoefman, Sven; De Vos, Paul; Boeckx, Pascal; Boon, Nico

    2014-04-01

    Biological treatment using methane-oxidizing bacteria (MOB) immobilized on six porous carrier materials have been used to mitigate methane emission. Experiments were performed with different MOB inoculated in building materials at high (~20 % (v/v)) and low (~100 ppmv) methane mixing ratios. Methylocystis parvus in autoclaved aerated concrete (AAC) exhibited the highest methane removal rate at high (28.5 ± 3.8 μg CH₄ g⁻¹ building material h⁻¹) and low (1.7 ± 0.4 μg CH₄ g⁻¹ building material h⁻¹) methane mixing ratio. Due to the higher volume of pores with diameter >5 μm compared to other materials tested, AAC was able to adsorb more bacteria which might explain for the higher methane removal observed. The total methane and carbon dioxide-carbon in the headspace was decreased for 65.2 ± 10.9 % when M. parvus in Ytong was incubated for 100 h. This study showed that immobilized MOB on building materials could be used to remove methane from the air and also act as carbon sink. PMID:24337222

  3. A flow reactor study of neopentane oxidation at 8 atmospheres: Experiments and modeling

    Energy Technology Data Exchange (ETDEWEB)

    Wang, S.; Miller, D.L.; Cernansky, N.P. [Drexel Univ., Philadelphia, PA (United States). Dept. of Mechanical Engineering and Mechanics; Curran, H.J.; Pitz, W.J.; Westbrook, C.K. [Lawrence Livermore National Lab., CA (United States)

    1999-08-01

    An existing detailed chemical kinetic reaction mechanism for neopentane oxidation is applied to new experimental measurements, taken in a flow reactor operating at a pressure of 8 atm. The reactor temperature ranged from 620 K to 810 K and flow rates of the reactant gases neopentane, oxygen, and nitrogen were 0.285, 7.6, and 137.1 standard liter per minute (SLM), respectively, producing an equivalence ratio of 0.3. Initial simulations identified some deficiencies in the existing model and the paper presents modifications which included upgrading the thermodynamic parameters of alkyl radical and alkylperoxy radical species, adding an alternative isomerization reaction of hydroperoxy-neopentyl-peroxy, and a multistep reaction sequence for 2-methylpropan-2-yl radical with molecular oxygen. These changes improved the calculation for the overall reactivity and the concentration profiles of the following primary products: formaldehyde, acetone, isobutene; 3,3-dimethyloxetane, methacrolein, carbon monoxide, carbon dioxide, and water. Experiments indicate that neopentane shows negative temperature coefficient behavior similar to other alkanes, though it is not as pronounced as that shown by n-pentane for example. Modeling results indicate that this behavior is caused by the {beta}-scission of the neopentyl radical and the chain propagation reactions of the hydroperoxyl-neopentyl radical.

  4. Influence of packaging atmosphere on the formation of cholesterol oxides in [gamma]-irradiated egg powder

    Energy Technology Data Exchange (ETDEWEB)

    Lebovics, V.K.; Gaal, O. (National Inst. of Food Hygiene and Nutrition, Budapest (Hungary)); Farkas, J.; Somogyi, L. (University of Horticulture and Food Industry, Budapest (Hungary))

    1993-09-01

    In the present work the influence of aerobic and anoxic conditions have been comparatively investigated to study the chemical changes of cholesterol in [gamma]-irradiated egg powder. The irradiation treatment was carried out with powdered egg packed under air and also under vacuum in polyethylene (PE) bags and in laminated, oxygen impermeable three-layer (polyester-aluminium-polyethylene) foil to dosage levels 2 and 4 kGy at room temperature. The cholesterol oxidation is demonstrated by thin-layer chromatograms. In the egg powder wrapped in Pe bags the predominant cholesterol derivatives -7-hydroxycholesterol isomers ([alpha] and [beta]) - accumulated in significant amounts (increasing with dose) while vacuum-packaging in laminated foil considerably suppressed the quantity of these products and prevented the formation of cholesterol 5[alpha], 6[alpha]-epoxide as well as 7-ketocholesterol. Little or no change was observed in non-irradiated (control) vacuum-packed egg powder stored at approximately 22[sup o]C for up to 5 months. Peroxide values showed changes parallel to the formation of COPs. (author).

  5. Modelling of gaseous dimethylamine in the global atmosphere: impacts of oxidation and aerosol uptake

    Directory of Open Access Journals (Sweden)

    F. Yu

    2014-07-01

    Full Text Available Recent laboratory studies indicate that while a dimethylamine concentration ([DMA] of several pptv can substantially enhance nucleation rates, such an enhancement drops significantly as [DMA] decreases below a few pptv. Here we study global distributions of amines with a chemistry transport model. DMA's lifetime is quite short (1–2 h in some regions due to aerosol uptake and oxidation. Aerosol uptake is important over regions of high anthropogenic emissions, while the decrease of the uptake coefficient (γ from 0.03 to 0.001 in these regions increases the modeled amine concentrations by a factor of ~5. Further decrease of γ from 0.001 to 0 has a small (<10% effect on the predicted amine concentrations. With the estimated global emission flux, from the reference, our simulations indicate that [DMA] in the surface layer is generally less than 1 pptv over major continents and below 0.1 pptv over oceans, decreasing quickly with altitude. Total concentrations of methylamines are about one order of magnitude higher than that of DMA. A comparison of simulated and observed [DMA] shows that the values of the simulated [DMA] are close to the measured values for the various urban sites but are substantially lower (by 1–2 orders of magnitude than those measured at the rural, coastal, and marine sites.

  6. Self-sealing of unsealed aluminium anodic oxide films in very different atmospheres

    Directory of Open Access Journals (Sweden)

    González, J. A.

    2003-12-01

    Full Text Available It is widely believed that the corrosion resistance behaviour of bare aluminium in natural environments is superior to that of unsealed anodised aluminium. However, results obtained in the exposure of unsealed anodised aluminium specimens with three different film thicknesses, in 9 atmospheres of Ibero-America with salinity levels between 3.9 and 517 mg.m-2.d-1 chloride, clearly shows the reverse to be true. After a sufficient time, which is shorter the higher the precipitation rate and the environmental relative humidity, a self-sealing process takes place, leading to coatings that surpass the quality standards demanded in industrial practice. Anodic films, sealed and unsealed, are protective coatings whose quality improves with ageing in most natural environments.

    Está muy difundida la idea de que el comportamiento del aluminio es superior al del aluminio anodizado y sin sellar, desde el punto de vista de la resistencia a la corrosión, en los ambientes naturales. Sin embargo, los resultados obtenidos en la exposición de anodizados sin sellar, de tres espesores diferentes, a 9 atmósferas de Iberoamérica, con salinidades comprendidas entre 3,9 y 517 mg.m-2.d-1 de cloruros, muestran, sin lugar a dudas, lo contrario. Con tiempo suficiente, tanto más rápidamente cuanto mayor sean las precipitaciones y la humedad relativa ambiental, tiene lugar un proceso de autosellado que conduce a recubrimientos que superan las normas de calidad exigidas en la práctica industrial. Los anodizados, sellados y sin sellar, son recubrimientos protectores que mejoran su calidad, en la mayoría de los ambientes naturales, con el envejecimiento.

  7. Mechanism and kinetics study on the OH-initiated oxidation of organophosphorus pesticide trichlorfon in atmosphere

    Energy Technology Data Exchange (ETDEWEB)

    Bao, Yuan; Zhang, Chenxi; Yang, Wenbo; Hu, Jingtian [Environment Research Institute, Shandong University, Jinan 250100 (China); Sun, Xiaomin, E-mail: sxmwch@sdu.edu.cn [Environment Research Institute, Shandong University, Jinan 250100 (China); State Key Laboratory of Solid Lubrication, Lanzhou Institute of Chemical Physics, Chinese Academy Of Science, Lanzhou 730000 (China)

    2012-03-01

    Trichlorfon [O,O-dimethyl-(2,2,2-trichloro-1-hydroxy-ethyl) phosphonate] (TCF) is a kind of widely used organophosphorus pesticides. In this paper, the mechanism and possible oxidation products for the OH-initiated reactions of TCF are studied at the MPWB1K/6-311 + G(3df,2p)//MPWB1K/6-31 + G(d,p) level. The study shows that H abstraction reaction from the CH{sub 3} group and the CH group as well as OH addition reaction to the P atom are energetically favorable for the reactions of TCF and the main products are (CH{sub 3}O){sub 2}POOH (P1), CCl{sub 3}CHOHPOOH(OCH{sub 3}) (P2), CH{sub 3}OPO{sub 2} (P3), CCl{sub 3}COPO(OCH{sub 3}){sub 2} (P6) and HCHO. On the basis of the quantum chemical information, the kinetic calculation is performed and the rate constants are calculated over a temperature range of 200-800 K using the transition state theory and canonical variational transition state theory with small-curvature tunneling effect. The Arrhenius formulas of rate constants with the temperature are fitted and the lifetimes of the reaction species in the troposphere are estimated according to the rate constants, which can provide helpful information for the model simulation study. - Highlights: Black-Right-Pointing-Pointer The H-abstracted reaction and OH addition reaction are favorable channels. Black-Right-Pointing-Pointer The Arrhenius formulas of rate constants with the temperature are fitted. Black-Right-Pointing-Pointer The rate constants of TCF relative to OH radical is 4.95 Multiplication-Sign 10{sup -15} cm{sup 3} molecule{sup -1} s{sup -1}.

  8. Snowpack-atmosphere gas exchanges of carbon dioxide, ozone, and nitrogen oxides at a hardwood forest site in northern Michigan

    Directory of Open Access Journals (Sweden)

    Brian Seok

    2015-03-01

    Full Text Available Abstract Snowpack-atmosphere gas exchanges of CO2, O3, and NOx (NO + NO2 were investigated at the University of Michigan Biological Station (UMBS, a mid-latitude, low elevation hardwood forest site, during the 2007–2008 winter season. An automated trace gas sampling system was used to determine trace gas concentrations in the snowpack at multiple depths continuously throughout the snow-covered period from two adjacent plots. One natural plot and one with the soil covered by a Tedlar sheet were setup for investigating whether the primary source of measured trace gases was biogenic (i.e., from the soil or non-biogenic (i.e., from the snowpack. The results were compared with the “White on Green” study conducted at the Niwot Ridge (NWT Long Term Ecological Research site in Colorado. The average winter CO2 flux ± s.e. from the soil at UMBS was 0.54 ± 0.037 µmol m-2 s-1 using the gradient diffusion method and 0.71 ± 0.012 µmol m-2 s-1 using the eddy covariance method, and in a similar range as found for NWT. Observed snowpack-O3 exchange was also similar to NWT. However, nitrogen oxides (NOx fluxes from snow at UMBS were 10 times smaller than those at NWT, and fluxes were bi-directional with the direction of the flux dependent on NOx concentrations in ambient air. The compensation point for the change in the direction of NOx flux was estimated to be 0.92 nmol mol-1. NOx in snow also showed diurnal dependency on incident radiation. These NOx dynamics in the snow at UMBS were notably different compared to NWT, and primarily determined by snow-atmosphere interactions rather than by soil NOx emissions.

  9. A Comparison of Process-Scale Modeling and Measurements of Atmosphere-Snowpack Exchange of Nitrogen Oxides at Summit, Greenland

    Science.gov (United States)

    Murray, K. A.; Helmig, D.; Kramer, L. J.; Doskey, P. V.; Van Dam, B. A.; Seok, B.; Ganzeveld, L.

    2015-12-01

    Snowpack over glacial ice is a reservoir for reactive nitrogen gases. Previous studies indicate nitrogen oxides (NOx) are generated in snowpack interstitial air through photolysis of nitrate (NO3-). Gradients in NOx mixing ratios between snowpack interstitial air and the overlying atmosphere regulate NOx surface exchange, which affects the Arctic ozone budget and climate. To better understand the dynamics of cryosphere-atmosphere exchange of NOx in the Arctic, we use a 1-D process-scale model to evaluate measurements of NOxin and above the snowpack during March-May 2009 at Summit, Greenland. The model is based upon the processes previously presented in the snowpack chemistry and physics model, MISTRA-SNOW, which represents snow grains as spheres with surfaces uniformly coated by an aqueous phase. Modeled profiles of NO, NO2, and O3 up to ~ 2 meters deep into the snowpack for March-May 2009 have been compared to measured profiles and will be presented. During the March-May time period at Summit, low irradiances are observed during March, diurnal irradiance profiles are observed during April, and the sun never sets in May. The model results suggest a key chemical pathway for the formation of NO2 during "nighttime" that was previously unexplained. In addition, modeled 24-hour NOx fluxes are compared to measured NOx fluxes from a MET tower at Summit. Modeled fluxes of NOx in April 2009 are the same order of magnitude as the measurements; however, modeled fluxes of NOx deviate up to one order of magnitude from measurements in May 2009. A detailed analysis of the modeled/measured flux comparison will be presented.

  10. Oxidative capacity of the Mexico City atmosphere – Part 1: A radical source perspective

    Directory of Open Access Journals (Sweden)

    M. J. Molina

    2007-04-01

    Full Text Available A detailed analysis of OH, HO2 and RO2 radical sources is presented for the near field photochemical regime inside the Mexico City Metropolitan Area (MCMA. During spring of 2003 (MCMA-2003 field campaign an extensive set of measurements was collected to quantify time resolved ROx (sum of OH, HO2, RO2 radical production rates from day- and nighttime radical sources. The Master Chemical Mechanism (MCMv3.1 was constrained by measurements of (1 concentration time-profiles of photosensitive radical precursors, i.e., nitrous acid (HONO, formaldehyde (HCHO, ozone (O3, glyoxal (CHOCHO, and other oxygenated volatile organic compounds (OVOCs; (2 respective photolysis-frequencies (J-values; (3 concentration time-profiles of alkanes, alkenes, and aromatic VOCs (103 compound are treated and oxidants, i.e., OH- and NO3 radicals, O3; and (4 NO, NO2, meteorological and other parameters. The ROx production rate was calculated directly from these observations; MCM was used to estimate further ROx production from unconstrained sources, and express overall ROx production as OH-equivalents (i.e., taking into account the propagation efficiencies of RO2 and HO2 radicals into OH radicals. Daytime radical production is found to be about 10-25 times higher than at night; it does not track the abundance of sunlight. 12-h average daytime contributions of individual sources are: HCHO and O3 photolysis, each about 20%; O3/alkene reactions and HONO photolysis, each about 15%; unmeasured sources about 30%. While the direct contribution of O3/alkene reactions appears to be moderately small, source-apportionment of ambient HCHO and HONO identifies O3/alkene reactions as being largely responsible for jump-starting photochemistry about one hour after sunrise. The peak radical production is found to be higher than in any other urban influenced environment studied to date; further, differences exist in the timing of radical production. Our measurements and analysis comprise a

  11. Measurement and Modeling of Site-specific Nitrogen and Oxygen Isotopic Composition of Atmospheric Nitrous Oxide at Mace Head, Ireland

    Science.gov (United States)

    McClellan, M. J.; Saikawa, E.; Prinn, R. G.; Ono, S.

    2015-12-01

    Global mixing ratios of atmospheric nitrous oxide (N2O), a potent greenhouse gas, have increased nearly linearly from the beginning of the modern industrial period to today, with the current global average in excess of 325 ppb. This increase can be largely attributed to anthropogenic activity above the level of N2O emissions from natural biotic sources. The effect of N2O on Earth's climate is twofold: in the troposphere, N2O is radiatively active and chemically inert, while it serves as a reactive source of ozone-destroying nitrogen oxides in the stratosphere. The marked altitudinal divide in its reactivity means that all stages in the N2O life cycle—emission, transport, and destruction—must be examined to understand the overall effect of N2O on Earth's climate. However, the understanding of the total impact of N2O is incomplete, as there remain significant uncertainties in the global budget of this gas. Due to unique isotopic substitutions (15N and 18O) made by different N2O sources and stratospheric chemical reactions, the measurement of N2O isotopic ratios in ambient air can help identify the distribution and magnitude of distinct source types. We present the first year of site-specific nitrogen and oxygen isotopic composition data from the MIT Stheno-tunable infrared direct absorption spectroscopy (TILDAS) instrument at Mace Head, Ireland. Aided by the Stheno preconcentration system, Stheno-TILDAS can achieve measurement precisions of 0.10‰ or greater for all isotopic ratios (δ15N and δ18O) in ambient N2O. We further compare these data to the results from Model for Ozone and Related Tracers version 4 (MOZART-4) simulations, including N2O isotopic fractionation processes and MERRA/GEOS-5 reanalysis meteorological fields. These results will form the basis of future Bayesian inverse modeling simulations that will constrain global N2O source, circulation, and sink dynamics better.

  12. Dissociation against oxidation kinetics for the conversion of VOCs in non-thermal plasmas of atmospheric gases

    Science.gov (United States)

    Pasquiers, Stéphane; Blin-Simiand, Nicole; Magne, Lionel

    2016-08-01

    The kinetics of four volatile organic compounds (VOCs) (propene, propane, acetaldehyde, acetone) were studied in plasmas of atmospheric gases using a photo-triggered discharge (homogeneous plasma) or a dielectric barrier discharge (filamentary plasma). It was shown for the homogeneous plasma that quenchings of nitrogen metastable states, A3Ʃ+u and the group of singlets a' 1Ʃ-u, a 1Πg and w 1∆u, are important processes for the decomposition of such molecules. Recent measurements of the H2 concentration produced in the N2/C3H6 mixture emphasize that the hydrogen molecule can be an exit route for propene dissociation. It is also found that H2 and CO molecules are efficiently produced following the dissociation of CH3COCH3 and the subsequent chemical reactivity induced by radicals coming from acetone. Addition of oxygen to a N2/VOC mixture can change drastically the kinetics. However, the quenching processes of N2 metastables by the VOC are always present and compete with oxidation reactions for the conversion of the pollutant. At low temperature, oxidations by O or by OH are not always sufficiently effective to induce an increase of the molecule decomposition when oxygen is added to the mixture. In particular, the presence of O2 has a detrimental effect on the acetone removal. Also, as evidenced for acetaldehyde and propane, some kinetic analogies appear between filamentary and homogeneous plasmas. Contribution to the topical issue "6th Central European Symposium on Plasma Chemistry (CESPC-6)", edited by Nicolas Gherardi, Ester Marotta and Cristina Paradisi

  13. Non-OH chemistry in oxidation flow reactors for the study of atmospheric chemistry systematically examined by modeling

    Directory of Open Access Journals (Sweden)

    Z. Peng

    2015-09-01

    Full Text Available Oxidation flow reactors (OFRs using low-pressure Hg lamp emission at 185 and 254 nm produce OH radicals efficiently and are widely used in atmospheric chemistry and other fields. However, knowledge of detailed OFR chemistry is limited, allowing speculation in the literature about whether some non-OH reactants, including several not relevant for tropospheric chemistry, may play an important role in these OFRs. These non-OH reactants are UV radiation, O(1D, O(3P, and O3. In this study, we investigate the relative importance of other reactants to OH for the fate of reactant species in OFR under a wide range of conditions via box modeling. The relative importance of non-OH species is less sensitive to UV light intensity than to relative humidity (RH and external OH reactivity (OHRext, as both non-OH reactants and OH scale roughly proportional to UV intensity. We show that for field studies in forested regions and also the urban area of Los Angeles, reactants of atmospheric interest are predominantly consumed by OH. We find that O(1D, O(3P, and O3 have relative contributions to VOC consumption that are similar or lower than in the troposphere. The impact of O atoms can be neglected under most conditions in both OFR and troposphere. Under "pathological OFR conditions" of low RH and/or high OHRext, the importance of non-OH reactants is enhanced because OH is suppressed. Some biogenics can have substantial destructions by O3, and photolysis at non-tropospheric wavelengths (185 and 254 nm may also play a significant role in the degradation of some aromatics under pathological conditions. Working under low O2 with the OFR185 mode allows OH to completely dominate over O3 reactions even for the biogenic species most reactive with O3. Non-tropospheric VOC photolysis may have been a problem in some laboratory and source studies, but can be avoided or lessened in future studies by diluting source emissions and working at lower precursor concentrations in lab

  14. Seasonal variability of atmospheric nitrogen oxides and non-methane hydrocarbons at the GEOSummit station, Greenland

    Directory of Open Access Journals (Sweden)

    L. J. Kramer

    2014-05-01

    Full Text Available Measurements of atmospheric NOx (NOx = NO + NO2, peroxyacetyl nitrate (PAN, NOy and non-methane hydrocarbons (NMHC were taken at the GEOSummit Station, Greenland (72.34° N, 38.29° W, 3212 m.a.s.l from July 2008 to July 2010. The data set represents the first year-round concurrent record of these compounds sampled at a high latitude Arctic site in the free troposphere. Here, the study focused on the seasonal variability of these important ozone (O3 precursors in the Arctic free troposphere and the impact from transported anthropogenic and biomass burning emissions. Our analysis shows that PAN is the dominant NOy species in all seasons at Summit, varying from 49% to 78%, however, we find that odd NOy species (odd NOy = NOy − PAN-NOx contribute a large amount to the total NOy speciation with monthly means of up to 95 pmol mol−1 in the winter and ∼40 pmol mol−1 in the summer, and that the level of odd NOy species at Summit during summer is greater than that of NOx. We hypothesize that the source of this odd NOy is most likely alkyl nitrates from transported pollution, and photochemically produced species such as HNO3 and HONO. FLEXPART retroplume analysis and tracers for anthropogenic and biomass burning emissions, were used to identify periods when the site was impacted by polluted air masses. Europe contributed the largest source of anthropogenic emissions during the winter and spring months, with up to 82% of the simulated anthropogenic black carbon originating from this region between December 2009 and March 2010, whereas, North America was the primary source of biomass burning emissions. Polluted air masses were typically aged, with median transport times to the site from the source region of 11 days for anthropogenic events in winter, and 14 days for BB plumes. Overall we find that the transport of polluted air masses to the high altitude Arctic typically resulted in high variability in levels of O3 and O3 precursors. During winter

  15. Surface and optical properties of indium tin oxide layer deposition by RF magnetron sputtering in argon atmosphere

    Science.gov (United States)

    Yudar, H. Hakan; Korkmaz, Şadan; Özen, Soner; Şenay, Volkan; Pat, Suat

    2016-08-01

    This study focused on the characterization and properties of transparent and conductive indium tin oxide (ITO) thin films deposited in argon atmosphere. ITO thin films were coated onto glass substrates by radio frequency (RF) magnetron sputtering technique at 75 and 100 W RF powers. Structural characteristics of producing films were investigated through X-ray diffraction analysis. UV-Vis spectrophotometer and interferometer were used to determine transmittance, absorbance and reflectance values of samples. The surface morphology of the films was characterized by atomic force microscope. The calculated band gaps were 3.8 and 4.1 eV for the films at 75 and 100 W, respectively. The effect of RF power on crystallinity of prepared films was explored using mentioned analysis methods. The high RF power caused higher poly crystallinity in the produced samples. The thickness and refractive index values for all samples increased respect to an increment of RF power and were calculated as 20, 50 nm and 1.71, 1.86 for samples at 75 and 100 W, respectively. Finally, the estimated grain sizes for all prepared films decreased with increasing of 2 θ degrees, and the number of crystallite per unit volume was calculated. It was found that nearly all properties including sheet resistance and resistivity depend on the RF power.

  16. Evaporation rates and vapor pressures of individual aerosol species formed in the atmospheric oxidation of alpha- and beta-pinene.

    Science.gov (United States)

    Bilde, M; Pandis, S N

    2001-08-15

    The semivolatile oxidation products (trans-norpinic acid, pinic acid, cis-pinonic acid, etc.) of the biogenic monoterpenes (alpha-pinene, beta-pinene, etc.) contribute to the atmospheric burden of particulate matter. Using the tandem differential mobility analysis (TDMA) technique evaporation rates of glutaric acid, trans-norpinic acid, and pinic acid particles were measured in a laminar flow reactor. The vapor pressure of glutaric acid was found to be log(p0 glutaric/Pa) = - 3,510 K/T + 8.647 over the temperature range 290-300 K in good agreement with the values previously reported by Tao and McMurry (1989). The measured vapor pressure of trans-norpinic acid over the temperature range 290-312 K is log(p0 norpinic/Pa) = - 2,196.9 K/T + 3.522, and the vapor pressure of pinic acid is log(p0 pinic/ Pa) = - 5,691.7 K/T + 14.73 over the temperature range 290-323 K. The uncertainty on the reported vapor pressures is estimated to be approximately +/- 50%. The vapor pressure of cis-pinonic acid is estimated to be of the order of 7 x 10(-5) Pa at 296 K.

  17. Experimental and modeling study of the oxidation of acetaldehyde in an atmospheric-pressure pulsed corona discharge

    Science.gov (United States)

    Klett, C.; Touchard, S.; Vega-Gonzalez, A.; Redolfi, M.; Bonnin, X.; Hassouni, K.; Duten, X.

    2012-08-01

    This paper reports the results obtained for the degradation of acetaldehyde by an atmospheric plasma corona discharge working in a pulsed regime. It was shown that a few hundred ppm of acetaldehyde diluted in a pure N2 gas flow can be removed up to 80% by a discharge fed with an electric power lower than 1 W. Under the same conditions, adding up to 5% of O2 allowed the removal of up to 95% of the initial acetaldehyde. The main identified end products were CO2, CO and methanol. A quasi-homogeneous zero-dimensional chemical model was developed to investigate the respective efficiency of the discharge and post-discharge periods in the global removal of the pollutant. The identified main pathways of acetaldehyde degradation were quenching of N2 metastable states during plasma pulses and oxidation by O and OH radicals during the post-discharge. This latter contribution increased with input power because of ozone accumulation in the gas mixture acting as an additional oxygen reservoir.

  18. Vanillic and syringic acids from biomass burning: Behaviour during Fenton-like oxidation in atmospheric aqueous phase and in the absence of light.

    Science.gov (United States)

    Santos, Gabriela T A D; Santos, Patrícia S M; Duarte, Armando C

    2016-08-01

    Biomass combustion is a threat to the environment since it emits to the atmosphere organic compounds, which may react and originate others more aggressive. This work studied the behaviours of vanillic and syringic acids, small aromatic tracers of biomass burning, during Fenton-like oxidation in aqueous phase and absence of light. For both compounds, the extent of oxidation increased with pH decrease from neutral to acid in atmospheric waters, but for vanillic acid the neutral pH was not able of promoting the oxidation. With the oxidation of both acids were formed chromophoric compounds, and the formation rate increased with the degree of electron-donator substituents in benzene ring. The initial and produced compounds were not totally degraded up to 24h of reaction at pH 4.5, suggesting that the night period may be not sufficient for their full degradation in atmospheric waters. The major compounds formed were the 3,4-dihydroxybenzoic acid for vanillic acid, and the 1,4-dihydroxy-2,6-dimethoxybenzene for syringic acid. These findings suggest the occurrence of an ipso attack by the hydroxyl radical preferential to the methoxy and carboxyl groups of vanillic and syringic acids, respectively. It is important to highlight that for both aromatic acids the main compounds produced are also small aromatic compounds. PMID:27085101

  19. Partial conductivities in perovskites CaZr1- x Sc x O3-α ( x = 0.03-0.20) in an oxidation atmosphere

    Science.gov (United States)

    Gorelov, V. P.; Balakireva, V. B.; Kuz'min, A. V.

    2016-01-01

    Partial (ionic, proton, and hole) conductivities of oxides CaZr1- x Sc x O3-α( x = 0.03-0.20) with the perovskite structure in air atmosphere have been studied as functions of temperature in the range of 600-900°C and partial water-vapor pressure in the range of {P_{{H_2}O}}= 40-2500 Pa. The influence of the humidity of the atmosphere on the relative change in the concentration of oxygen vacancies as a function of temperature has been estimated.

  20. Photocatalytic Decomposition of Methyl Red Dye by Using Nanosized Zinc Oxide Deposited on Glass Beads in Various pH and Various Atmosphere

    Directory of Open Access Journals (Sweden)

    H. R. Ebrahimi

    2013-01-01

    Full Text Available Photocatalytic decomposition of methyl red (MR as a pollutant in wastewater samples is investigated in this study. This photodegradation was investigated in water in neutral, alkaline, and acidic media under external UV light irradiation by zinc oxide nanosized catalysts on granule glass. The effect of four atmosphere types including air, nitrogen, oxygen, and argon was investigated. Finally, it was found that photodecomposition using nanosized ZnO layered on glass is a new alternative route for efficient wastewater treatment. The results showed that the titled dye is degraded by various rate under different atmosphere and pH.

  1. The magnetic and oxidation behavior of bare and silica-coated iron oxide nanoparticles synthesized by reverse co-precipitation of ferrous ion (Fe{sup 2+}) in ambient atmosphere

    Energy Technology Data Exchange (ETDEWEB)

    Mahmed, N., E-mail: norsuria.mahmed@aalto.fi [Aalto University School of Chemical Technology, Department of Materials Science and Engineering, P.O. Box 16200, FI-00076 Aalto (Finland); School of Materials Engineering, Kompleks Pusat Pengajian UniMAP, Taman Muhibbah, Universiti Malaysia Perlis, 02600 Jejawi, Perlis (Malaysia); Heczko, O., E-mail: heczko@fzu.cz [Institute of Physics, Academy of Sciences, Czech Republic Na Slovance 2, CZ-182 21 Praha 8 (Czech Republic); Lancok, A., E-mail: Lancok@seznam.cz [Institute of Physics, Academy of Sciences, Czech Republic Na Slovance 2, CZ-182 21 Praha 8 (Czech Republic); Hannula, S-P., E-mail: simo-pekka.hannula@aalto.fi [Aalto University School of Chemical Technology, Department of Materials Science and Engineering, P.O. Box 16200, FI-00076 Aalto (Finland)

    2014-03-15

    The synthesis of iron oxide nanoparticles, i.e., magnetite was attempted by using only ferrous ion (Fe{sup 2+}) as a magnetite precursor, under an ambient atmosphere. The room temperature reverse co-precipitation method was used, by applying two synthesis protocols. The freshly prepared iron oxide was also immediately coated with Stöber silica (SiO{sub 2}) layer, forming the coreshell structure. The phase, stoichiometry, crystallite and the particle size of the synthesized powders were determined by using X-ray diffraction (XRD) and transmission electron microscope (TEM), while the magnetic and oxidation behaviors were studied by using the vibrating sample magnetometer (VSM) and Mössbauer spectroscopy. Based on the results, the bare iron oxide nanoparticles are in the stoichiometry between the magnetite and the maghemite stoichiometry, i.e., oxidation occurs. This oxidation is depending on the synthesis protocols used. With the silica coating, the oxidation can be prevented, as suggested by the fits of Mössbauer spectra and low temperature magnetic measurement. - Highlights: • Synthesis of magnetite was attempted by using ferrous ion (Fe{sup 2+}) in air. • The synthesized particle has a stoichiometry in between magnetite and maghemite. • Silica shell partly prevented the oxidation as suggested by magnetic and Mössbauer study.

  2. Non-OH chemistry in oxidation flow reactors for the study of atmospheric chemistry systematically examined by modeling

    Science.gov (United States)

    Peng, Zhe; Day, Douglas A.; Ortega, Amber M.; Palm, Brett B.; Hu, Weiwei; Stark, Harald; Li, Rui; Tsigaridis, Kostas; Brune, William H.; Jimenez, Jose L.

    2016-04-01

    Oxidation flow reactors (OFRs) using low-pressure Hg lamp emission at 185 and 254 nm produce OH radicals efficiently and are widely used in atmospheric chemistry and other fields. However, knowledge of detailed OFR chemistry is limited, allowing speculation in the literature about whether some non-OH reactants, including several not relevant for tropospheric chemistry, may play an important role in these OFRs. These non-OH reactants are UV radiation, O(1D), O(3P), and O3. In this study, we investigate the relative importance of other reactants to OH for the fate of reactant species in OFR under a wide range of conditions via box modeling. The relative importance of non-OH species is less sensitive to UV light intensity than to water vapor mixing ratio (H2O) and external OH reactivity (OHRext), as both non-OH reactants and OH scale roughly proportionally to UV intensity. We show that for field studies in forested regions and also the urban area of Los Angeles, reactants of atmospheric interest are predominantly consumed by OH. We find that O(1D), O(3P), and O3 have relative contributions to volatile organic compound (VOC) consumption that are similar or lower than in the troposphere. The impact of O atoms can be neglected under most conditions in both OFR and troposphere. We define "riskier OFR conditions" as those with either low H2O ( 200 s-1 in OFR254). We strongly suggest avoiding such conditions as the importance of non-OH reactants can be substantial for the most sensitive species, although OH may still dominate under some riskier conditions, depending on the species present. Photolysis at non-tropospheric wavelengths (185 and 254 nm) may play a significant (> 20 %) role in the degradation of some aromatics, as well as some oxidation intermediates, under riskier reactor conditions, if the quantum yields are high. Under riskier conditions, some biogenics can have substantial destructions by O3, similarly to the troposphere. Working under low O2 (volume mixing

  3. Methane and nitrous oxide measurements onboard the UK Atmospheric Research Aircraft using quantum cascade laser spectrometry (QCL)

    Science.gov (United States)

    Muller, J. B.; O'Shea, S.; Dorsey, J.; Bauguitte, S.; Cain, M.; Allen, G.; Percival, C. J.; Gallagher, M. W.

    2012-12-01

    A Aerodyne Research© Mini-Quantum Cascade Laser (QCL) spectrometer was installed on the UK Facility of Airborne Atmospheric Measurements (FAAM) BAe-146 research aircraft and employed during summer 2012. Methane (CH4) and nitrous oxide (N2O) concentrations were measured within the Arctic Circle as part of the MAMM project (Methane and other greenhouse gases in the Arctic - Measurements, process studies and Modelling) as well as around the UK as part of the ClearfLo project (Clean Air for London). A range of missions were flown, including deep vertical profiles up to the stratosphere, providing concentration profiles of CH4 and N2O, as well as low altitude level runs exploring near surface diffuse emission sources such as the wetlands in Arctic Lapland and point emissions sources such as gas platforms off the UK coast. Significant pollution plumes were observed both in the Arctic and around the UK with elevated CH4 concentrations, as well as enhanced CO, O3 and aerosol levels. The NAME Lagrangian particle dispersion model will be used to investigate the origins of these CH4 plumes to identify the locations of the emissions sources. The first set of flights using QCL on the FAAM research aircraft have been successful and regular in-flight calibrations (high/low span) and target concentrations were used to determine instrument accuracy and precision. Additional data quality control checks could be made by comparison with an onboard Los Gatos Fast Greenhouse Gas Analyser (FGGA) for CO2 and CH4 and provide the basis for further instrument development and implementation for future Arctic MAMM flights during spring and summer 2013.

  4. Atmospheric oxidation and antioxidants

    CERN Document Server

    Meurant, Gerard

    1993-01-01

    Volume I reviews current understanding of autoxidation, largely on the basis of the reactions of oxygen with characterised chemicals. From this flows the modern mechanism of antioxidant actions and their application in stabilisation technology.

  5. Atmospheric reactivity of hydroxyl radicals with guaiacol (2-methoxyphenol), a biomass burning emitted compound: Secondary organic aerosol formation and gas-phase oxidation products

    Science.gov (United States)

    Lauraguais, Amélie; Coeur-Tourneur, Cécile; Cassez, Andy; Deboudt, Karine; Fourmentin, Marc; Choël, Marie

    2014-04-01

    Methoxyphenols are low molecular weight semi-volatile polar aromatic compounds produced from the pyrolysis of wood lignin. The reaction of guaiacol (2-methoxyphenol) with hydroxyl radicals has been studied in the LPCA simulation chamber at (294 ± 2) K, atmospheric pressure, low relative humidity (RH Flame Ionization Detection) and GC-MS (Gas Chromatography - Mass Spectrometry) analysis show the formation of nitroguaiacol isomers as main oxidation products in the gas- and aerosol-phases. In the gas-phase, the formation yields were (10 ± 2) % for 4-nitroguaiacol (1-hydroxy-2-methoxy-4-nitrobenzene; 4-NG) and (6 ± 2) % for 3- or 6-nitroguaiacol (1-hydroxy-2-methoxy-3-nitrobenzene or 1-hydroxy-2-methoxy-6-nitrobenzene; 3/6-NG; the standards are not commercially available so both isomers cannot be distinguished) whereas in SOA their yield were much lower (≤0.1%). To our knowledge, this work represents the first identification of nitroguaiacols as gaseous oxidation products of the OH reaction with guaiacol. As the reactivity of nitroguaiacols with atmospheric oxidants is probably low, we suggest using them as biomass burning emission gas tracers. The atmospheric implications of the guaiacol + OH reaction are also discussed.

  6. Data on the identification and characterization of by-products from N-Cbz-3-aminopropanal and t-BuOOH/H2O2 chemical reaction in chloroperoxidase-catalyzed oxidations.

    Science.gov (United States)

    Masdeu, Gerard; Pérez-Trujillo, Míriam; López-Santín, Josep; Álvaro, Gregorio

    2016-09-01

    This data article is related to the subject of a publication in Process Biochemistry, entitled "Chloroperoxidase-catalyzed amino alcohol oxidation: Substrate specificity and novel strategy for the synthesis of N-Cbz-3-aminopropanal" (Masdeu et al., 2016) [1]. Here, the products of the chemical reaction involving the amino aldehyde (N-Cbz-3-aminopropanal) and peroxides (tert-butyl hydroperoxide and H2O2) are characterized by NMR. (1)H and (13)C NMR full characterization of the products was obtained based on 2D NMR, 1D selective NOESY and diffusion spectroscopy (DOSY) experiments. PMID:27437440

  7. Nitrous oxide in the Changjiang (Yangtze River Estuary and its adjacent marine area: Riverine input, sediment release and atmospheric fluxes

    Directory of Open Access Journals (Sweden)

    G.-L. Zhang

    2010-11-01

    Full Text Available Dissolved nitrous oxide (N2O was measured in the waters of the Changjiang (Yangtze River Estuary and its adjacent marine area during five surveys covering the period of 2002–2006. Dissolved N2O concentrations ranged from 6.04 to 21.3 nM, and indicate great temporal and spatial variations. Distribution of N2O in the Changjiang Estuary was influenced by multiple factors and the key factor varied between cruises. Dissolved riverine N2O was observed monthly at station Xuliujing of the Changjiang, and ranged from 12.4 to 33.3 nM with an average of 19.4 ± 7.3 nM. N2O concentrations in the river waters showed obvious seasonal variations with higher values occurring in both summer and winter. Annual input of N2O from the Changjiang to the estuary was estimated to be 15.0 × 106 mol/yr. N2O emission rates from the sediments of the Changjiang Estuary in spring ranged from −1.88 to 2.02 μmol m−2 d−1, which suggests that sediment can act as either a source or a sink of N2O in the Changjiang Estuary. Average annual sea-to-air N2O fluxes from the studied area were estimated to be 7.7 ± 5.5, 15.1 ± 10.8 and 17.0 ± 12.6 μmol m−2d−1 using LM86, W92 and RC01 relationships, respectively. Hence the Changjiang Estuary and its adjacent marine area are a net source of atmospheric N2O.

  8. Influence of NO2 and metal ions on oxidation of aqueous-phase S(IV in atmospheric concentrations

    Directory of Open Access Journals (Sweden)

    Cláudia R. Martins

    2008-06-01

    Full Text Available An investigation was made of the influence of atmospheric concentrations (15 or 130 ppbv of NO2 on the aqueous-phase oxidation rate of S(IV in the presence and absence of Fe(III, Mn(II and Cr(VI metal ions under controlled experimental conditions (pH, T, concentration of reactants, etc.. The reaction rate in the presence of the NO2 flow was slower than the reaction rate using only clean air with an initial S(IV concentration of 10-4 mol/L. NO2 appears to react with S(IV, producing a kind of inhibitor that slows down the reaction. Conversely, tenfold lower concentrations of S(IV ([S(IV]º = 10-5 mol/L caused a faster reaction in the presence of NO2 than the reaction using purified air. Under these conditions, therefore, the equilibrium shifts to sulfate formation. With the addition of Fe(III, Mn(II or Cr(VI in the presence of a NO2 flow, the reaction occurred faster under all the conditions in which S(IV oxidation was investigated.A reação de oxidação de S(IV em fase aquosa foi estudada em laboratório em presença de NO2 dos íons metálicos Fe(III, Mn(II, e Cr(VI sob condições experimentais controladas (pH, T, concentração dos reagentes, etc.. Na presença de corrente de ar com NO2 (15 ou 130 ppbv a reação de oxidação de S(IV ocorreu mais lentamente do que na presença de ar purificado, para uma concentração inicial de S(IV de 10-4 mol/L. Ao contrário, para concentração inicial de S(IV dez vezes menor ([S(IV]° = 10-5 mol/L a reação ocorreu mais rapidamente na presença de NO2. A explicação está relacionada com o equilíbrio envolvendo a formação de espécies intermediárias de longa vida, que impedem o prosseguimento da reação, porém a depender das concentrações relativas de S(IV e NO2, essas espécies se decompõem deslocando o equilíbrio no sentido de formação de sulfato. A adição dos íons Fe(III, Mn(II ou Cr(VI em presença de corrente de ar com NO2 indicou atividade catalítica para esses íons, em todas

  9. A simple way to obtain high saturation magnetization for superparamagnetic iron oxide nanoparticles synthesized in air atmosphere: Optimization by experimental design

    Science.gov (United States)

    Karaagac, Oznur; Kockar, Hakan

    2016-07-01

    Orthogonal design technique was applied to obtain superparamagnetic iron oxide nanoparticles with high saturation magnetization, Ms. Synthesis of the nanoparticles were done in air atmosphere according to the orthogonal table L934. Magnetic properties of the synthesized nanoparticles were measured by a vibrating sample magnetometer. Structural analysis of the nanoparticles was also carried out by X-ray diffraction technique (XRD), Fourier transform infrared spectroscopy (FTIR) and transmission electron microscopy (TEM). After the analysis of magnetic data, the optimized experimental parameters were determined as [Fe+2]/[Fe+3]=6/6, iron ion concentration=1500 mM, base concentration=6.7 M and reaction time=2 min. Magnetic results showed that the synthesis carried out according to the optimized conditions gave the highest Ms of 69.83 emu/g for the nanoparticles synthesized in air atmosphere. Magnetic measurements at 10 K and 300 K showed the sample is superparamagnetic at room temperature. Structural analysis by XRD, FTIR and selected area electron diffraction showed that the sample had the inverse spinel crystal structure of iron oxide. The particle size of the optimized sample determined from the TEM image is 7.0±2.2 nm. The results indicated that the Ms of superparamagnetic iron oxide nanoparticles can be optimized by experimental design with the suitable choice of the synthesis parameters.

  10. Atmospheric-Pressure DBD Cold Plasma for Preparation of High Active Au/P25 Catalysts for Low-Temperature CO Oxidation

    Institute of Scientific and Technical Information of China (English)

    DI Lanbo; ZHAN Zhibin; ZHANG Xiuling; QI Bin; XU Weijie

    2016-01-01

    Cold plasma generated by dielectric barrier discharge (DBD) at atmospheric pressure was adopted for preparation of commercial TiO2 Degussa P25 supported Au catalysts (Au/P25-P) with the assistance of the deposition-precipitation procedure.The influences of the plasma reduction time and calcination on the performance of the Au/P25-P catalysts were investigated.CO oxidation was performed to investigate the catalytic activity of thc Au/P25 catalysts.The results show that DBD cold plasma for the fabrication of Au/P25-P catalysts is a fast process,and Au/P25-P (4 min) exhibited the highest CO oxidation activity due to the complete reduction of Au compounds and less consumption of oxygen vacancies.In order to form more oxygen vacancies active species,Au/P25-P was calcined to obtain Au/P25-PC catalysts.Interestingly,Au/P25-PC exhibited the highest activity for CO oxidation among the Au/P25 samples.The results of transmission electron microscopy (TEM) indicated that the smaller size and high distribution of Au nanoparticles are the mean reasons for a high performance of Au/P25-PC.Atmospheric-pressure DBD cold plasma was proved to be of great efficiency in preparing high performance supported Au catalysts.

  11. Advanced Gasification By-Product Utilization

    Energy Technology Data Exchange (ETDEWEB)

    Rodney Andrews; Aurora Rubel; Jack Groppo; Ari Geertsema; Frank Huggins; M. Mercedes Maroto-Valer; Brandie M. Markley; Harold Schobert

    2006-02-01

    With the recent passing of new legislation designed to permanently cap and reduce mercury emissions from coal-fired utilities, it is more important than ever to develop and improve upon methods of controlling mercury emissions. One promising technique is carbon sorbent injection into the flue gas of the coal-fired power plant. Currently, this technology is very expensive as costly commercially activated carbons are used as sorbents. There is also a significant lack of understanding of the interaction between mercury vapor and the carbon sorbent, which adds to the difficulty of predicting the amount of sorbent needed for specific plant configurations. Due to its inherent porosity and adsorption properties as well as on-site availability, carbons derived from gasifiers are potential mercury sorbent candidates. Furthermore, because of the increasing restricted use of landfilling, the coal industry is very interested in finding uses for these materials as an alternative to the current disposal practice. The results of laboratory investigations and supporting technical assessments conducted under DOE Subcontract No. DE-FG26-03NT41795 are reported for the period September 1, 2004 to August 31, 2005. This contract is with the University of Kentucky Research Foundation, which supports work with the University of Kentucky Center for Applied Energy Research and The Pennsylvania State University Energy Institute. The worked described was part of a project entitled ''Advanced Gasification By-Product Utilization''. This work involves the development of technologies for the separation and characterization of coal gasification slags from operating gasification units, activation of these materials to increase mercury and nitrogen oxide capture efficiency, assessment of these materials as sorbents for mercury and nitrogen oxides, and characterization of these materials for use as polymer fillers.

  12. Timing and characterization of the change in the redox state of uranium in Precambrian surface environments: A proxy for the oxidation state of the atmosphere

    Science.gov (United States)

    Pollack, Gerald D.

    The redox-sensitive geochemical behavior of uranium permits the use of Th/U ratios as a geochemical proxy for the oxidation state of the atmosphere and oceans during sedimentary processes. Due to the effects of post-depositional uranium mobility on Th/U ratios during events involving oxygenated fluids, direct measurements of Th/U ratios are often misleading, but the whole rock Pb isotope composition may be used to determine a sample's apparent time-integrated Th/U ratio (kappaa) and the timing associated with the onset of the U-Th-Pb geochemistry. Rare earth element (REE) concentrations were determined by isotope dilution mass spectrometry to evaluate the influence of multiple provenance components and potential mobility of Th, U, and Pb during post-depositional processes on the Th/U ratio. The Pb isotope compositions and REE concentrations were determined for six Paleoproterozoic sedimentary sequences, which were the focus of previous studies involving the timing of the rise of atmospheric oxygen. The Mount McRae Shale, Huronian Supergroup, and Zaonezhskaya Formation have been interpreted as experiencing post-depositional alteration (perhaps associated with orogenic events) due to Pb-Pb ages that are younger than the likely depositional age and observed fractionation of REE in chondrite normalized REE patterns and interelement REE ratios (e.g. La/Nd, La/Yb, Eu/Eu*). Similar geochemical proxies have been interpreted as sedimentary geochemical features of the Timeball Hill Formation, Hotazel Formation, and Sengoma Argillite Formation. This study of Paleoproterozoic sedimentary units constrains the onset of U-Th decoupling, most likely due to the onset of oxidative weathering conditions, began by 2.32 Ga, the latest. Index words. Pb isotopes, Rare earth elements, Th/U ratios, Time-integrated, Atmospheric evolution, Oxygen content of the atmosphere, U-Th decoupling

  13. Poisoning of noble metal catalysts by arsenic and silicon compounds in an oxidizing atmosphere. Die Vergiftung von Edelmetall-Katalysatoren durch Arsen- und Siliziumverbindungen unter oxidierenden Verbindungen

    Energy Technology Data Exchange (ETDEWEB)

    Kaizik, A.

    1984-01-12

    The dissertation deals with the poisoning of noble metal catalysts by arsenic and silicon compounds in an oxidizing atmosphere. The problem was studied in the field of catalytic exhaust and waste air post-combustion, but the findings can be applied to other catalytic processes in which arsenic and silicon compounds may occur as catalyst poisons. The following issues were investigated: 1. Kinetics of arsenic and silicon poisoning of platinum-containing carrier catalysts; 2. Regeneration of poisoned catalysts; 3. mathematical modelling of the poisoning processes.

  14. Electrical and optical properties of thin indium tin oxide films produced by pulsed laser ablation in oxygen or rare gas atmospheres

    DEFF Research Database (Denmark)

    Thestrup, B.; Schou, Jørgen; Nordskov, A.;

    1999-01-01

    Films of indium tin oxide (ITO) have been produced in different background gases by pulsed laser deposition (PLD). The Films deposited in rare gas atmospheres on room temperature substrates were metallic, electrically conductive, but had poor transmission of visible light. For substrate...... temperatures at 200 degrees C, the specific resistivity was reduced and the transmission of visible light enhanced for all background gases. Films produced in oxygen turned out to be superior to films deposited in other gases at the same temperature. (C) 1999 Elsevier Science B.V. All rights reserved....

  15. An investigation into the optimum thickness of titanium dioxide thin films synthesized by using atmospheric pressure chemical vapour deposition for use in photocatalytic water oxidation.

    Science.gov (United States)

    Hyett, Geoffrey; Darr, Jawwad A; Mills, Andrew; Parkin, Ivan P

    2010-09-10

    Twenty eight films of titanium dioxide of varying thickness were synthesised by using atmospheric pressure chemical vapour deposition (CVD) of titanium(IV) chloride and ethyl acetate onto glass and titanium substrates. Fixed reaction conditions at a substrate temperature of 660 °C were used for all depositions, with varying deposition times of 5-60 seconds used to control the thickness of the samples. A sacrificial electron acceptor system composed of alkaline sodium persulfate was used to determine the rate at which these films could photo-oxidise water in the presence of 365 nm light. The results of this work showed that the optimum thickness for CVD films on titanium substrates for the purposes of water oxidation was ≈200 nm, and that a platinum coating on the reverse of such samples leads to a five-fold increase in the observed rate of water oxidation. PMID:20645333

  16. 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.

  17. Atmospheric nitric oxide and ozone at the WAIS Divide deep coring site: a discussion of local sources and transport in West Antarctica

    Science.gov (United States)

    Masclin, S.; Frey, M. M.; Rogge, W. F.; Bales, R. C.

    2013-09-01

    The first measurements of atmospheric nitric oxide (NO) along with observations of ozone (O3), hydroperoxides (H2O2 and MHP) and snow nitrate (NO3-) on the West Antarctic Ice Sheet (WAIS) were carried out at the WAIS Divide deep ice-coring site between 10 December 2008 and 11 January 2009. Average ±1σ mixing ratios of NO were 19 ± 31 pptv and confirmed prior model estimates for the summer boundary layer above WAIS. Mean ±1σ mixing ratios of O3 of 14 ± 4 ppbv were in the range of previous measurements from overland traverses across WAIS during summer, while average ±1σ concentrations of H2O2 and MHP revealed higher levels with mixing ratios of 743 ± 362 and 519 ± 238 pptv, respectively. An upper limit for daily average NO2 and NO emission fluxes from snow of 8.6 × 108 and 33.9 × 108 molecule cm-2 s-1, respectively, were estimated based on photolysis of measured NO3- and nitrite (NO2-) in the surface snowpack. The resulting high NOx emission flux may explain the little preservation of NO3- in snow (~ 30%) when compared to Summit, Greenland (75-93%). Assuming rapid and complete mixing into the overlying atmosphere, and steady state of NOx, these snow emissions are equivalent to an average (range) production of atmospheric NOx of 30 (21-566) pptv h-1 for a typical atmospheric boundary-layer depth of 250 (354-13) m. These upper bounds indicate that local emissions from the snowpack are a significant source of short-lived nitrogen oxides above the inner WAIS. The net O3 production of 0.8 ppbv day-1 triggered with NO higher than 2 pptv is too small to explain the observed O3 variability. Thus, the origins of the air masses reaching WAIS Divide during this campaign were investigated with a 4-day back-trajectory analysis every 4 h. The resulting 168 back trajectories revealed that in 75% of all runs air originated from the Antarctic coastal slopes (58%) and the inner WAIS (17%). For these air sources O3 levels were on average 13 ± 3 ppbv. The remaining 25% are

  18. Atmospheric nitric oxide and ozone at the WAIS Divide deep coring site: a discussion of local sources and transport in West Antarctica

    Directory of Open Access Journals (Sweden)

    S. Masclin

    2013-09-01

    Full Text Available The first measurements of atmospheric nitric oxide (NO along with observations of ozone (O3, hydroperoxides (H2O2 and MHP and snow nitrate (NO3– on the West Antarctic Ice Sheet (WAIS were carried out at the WAIS Divide deep ice-coring site between 10 December 2008 and 11 January 2009. Average ±1σ mixing ratios of NO were 19 ± 31 pptv and confirmed prior model estimates for the summer boundary layer above WAIS. Mean ±1σ mixing ratios of O3 of 14 ± 4 ppbv were in the range of previous measurements from overland traverses across WAIS during summer, while average ±1σ concentrations of H2O2 and MHP revealed higher levels with mixing ratios of 743 ± 362 and 519 ± 238 pptv, respectively. An upper limit for daily average NO2 and NO emission fluxes from snow of 8.6 × 108 and 33.9 × 108 molecule cm–2 s–1, respectively, were estimated based on photolysis of measured NO3– and nitrite (NO2– in the surface snowpack. The resulting high NOx emission flux may explain the little preservation of NO3– in snow (~ 30% when compared to Summit, Greenland (75–93%. Assuming rapid and complete mixing into the overlying atmosphere, and steady state of NOx, these snow emissions are equivalent to an average (range production of atmospheric NOx of 30 (21–566 pptv h–1 for a typical atmospheric boundary-layer depth of 250 (354–13 m. These upper bounds indicate that local emissions from the snowpack are a significant source of short-lived nitrogen oxides above the inner WAIS. The net O3 production of 0.8 ppbv day–1 triggered with NO higher than 2 pptv is too small to explain the observed O3 variability. Thus, the origins of the air masses reaching WAIS Divide during this campaign were investigated with a 4-day back-trajectory analysis every 4 h. The resulting 168 back trajectories revealed that in 75% of all runs air originated from the Antarctic coastal slopes (58% and the inner WAIS (17%. For these air sources O3 levels were on average 13 ± 3

  19. Anthropogenic emissions of oxidized sulfur and nitrogen into the atmosphere of the former Soviet Union in 1985 and 1990

    Energy Technology Data Exchange (ETDEWEB)

    Ryaboshapko, A.G.; Brukhanov, P.A.; Gromov, S.A.; Proshina, Yu.V; Afinogenova, O.G. [Institute of Global Climate and Ecology, Moscow (Russian Federation)

    1996-09-01

    Anthropogenic emissions of oxidized sulfur and nitrogen over the former Soviet Union for 1985 and 1990 were calculated on the basis of a combination of `bottom-up` and `top-down` approaches. Sulfur dioxide emissions from combustion of hard coal, brown coal, oil products, natural gas, shale oil, peat, wood as well as from metallurgy, sulfuric acid production, and cement production were estimated. Nitrogen oxides emissions were considered separately for large power plants, small power plants, industrial boilers, residential combustion units, and for transport. The sulfur and nitrogen emissions were spatially distributed over the former Soviet Union with 1 x 1 degree resolution. Data on 721 point sources of sulfur dioxide emissions and on the 242 largest power stations as nitrogen oxides sources were used. The area sources of both sulfur dioxide and nitrogen oxides were distributed according to the population density separately for about 150 administrative units of the former Soviet Union. 63 refs., 19 tabs.

  20. Oxidation of metals and alloys in controlled atmospheres using in situ transmission electron microscopy and Auger spectrography

    Science.gov (United States)

    Rao, D. B.; Heinemann, K.; Douglass, D. L.

    1976-01-01

    Single-crystalline thin films of copper were oxidized at an isothermal temperature of 425 C and at an oxygen partial pressure of .005 Torr in situ in a high-resolution electron microscope. The specimens were prepared by epitaxial vapor deposition onto polished 100 and 110 faces of rocksalt and mounted in a hot stage inside an ultra-high-vacuum specimen chamber of the microscope. Large amounts of sulfur, carbon, and oxygen were detected by Auger electron spectroscopy on the surface of the as-received films and were removed in situ by ion-sputter etching immediately prior to the oxidation. The nucleation and growth characteristics of Cu2O on Cu were studied. Results show that neither stacking faults nor dislocations are associated with the Cu2O nucleation sites. The growth of Cu2O nuclei is linear with time. The experimental findings, including results from oxygen dissolution experiments and from repetitive oxidation-reduction-oxidation sequences, fit well into the framework of an oxidation process involving (a) the formation of a surface-charge layer, (b) oxygen saturation in the metal and (c) nucleation, followed by surface diffusion of oxygen and bulk diffusion of copper for lateral and vertical oxide growth, respectively.

  1. Is carbon within the global terrestrial biosphere becoming more oxidized? Implications for trends in atmospheric O2

    OpenAIRE

    Randerson, JT; Masiello, CA; Still, CJ; Rahn, T.; POORTER, H.; Field, CB

    2006-01-01

    Measurements of atmospheric O2 and CO2 concentrations serve as a widely used means to partition global land and ocean carbon sinks. Interpretation of these measurements has assumed that the terrestrial biosphere contributes to changing O2 levels by either expanding or contracting in size, and thus serving as either a carbon sink or source (and conversely as either an oxygen source or sink). Here, we show how changes in atmospheric O2 can also occur if carbon within the terrestrial biosphere b...

  2. Surface water and atmospheric carbon dioxide and nitrous oxide observations by shipboard automated gas chromatography: Results from expeditions between 1977 and 1990

    Energy Technology Data Exchange (ETDEWEB)

    Weiss, R.F.; Van Woy, F.A.; Salameh, P.K. (Scripps Institution of Oceanography, La Jolla, CA (United States)); Sepanski, R.J. (Tennessee Univ., Knoxville, TN (United States). Energy, Environment and Resources Center)

    1992-12-01

    This document presents the results of surface water and atmospheric carbon dioxide (CO[sub 2]) and nitrous oxide (N[sub 2]O) measurements carried out by shipboard gas chromatography over the period 1977--1990. These data include results from 11 different oceanic surveys for a total of 41 expedition legs. Collectively, they represent a globally distributed sampling that includes locations in the Atlantic, Pacific, Indian, and Southern Oceans, as well as the Mediterranean and Red Seas. The measurements were made by an automated high-precision shipboard gas chromatographic system developed during the late 1970s and used extensively over the intervening years. This instrument measures CO[sub 2] by flame ionization after quantitative reaction to methane in a stream of hydrogen. Nitrous oxide is measured by a separate electron capture detector. The chromatographic system measures 196 dry-gas samples a day, divided equally among the atmosphere, gas equilibrated with surface water, a low-range gas standard, and a high-range gas standard.

  3. Chlorine dioxide and by-products in water distribution systems

    OpenAIRE

    Ferreira, Francisco Cardoso

    1991-01-01

    Chlorine dioxide is used as both a pre-oxidant and/or a post-disinfectant in several water treatment plants in the United States. Chlorine dioxide is associated with its byproducts chlorite and chlorate. Chlorine dioxide, chlorine, chlori te and chlorate were sampled in four distribution systems where chlorine dioxide is used for disinfection purposes: Charleston, WV, Columbus, GA, New Castle, PA, and Skagit, WA. The fate of chlorine dioxide and its by-products in dist...

  4. Morphology and structure evolution of tin-doped indium oxide thin films deposited by radio-frequency magnetron sputtering: The role of the sputtering atmosphere

    International Nuclear Information System (INIS)

    The microstructure and morphology evolution of tin-doped indium oxide (ITO) thin films deposited by radio-frequency magnetron sputtering in different sputtering atmospheres were investigated by X-ray diffraction, X-ray reflectivity, and atomic force microscopy. The surface roughness w increases with increasing film thickness df, and exhibits a power law behavior w ∼ dfβ. The roughness decreases with increasing O2 flow, while it increases with increasing H2 flow. The growth exponent β is found to be 0.35, 0.75, and 0.98 for depositions in Ar/10%O2, pure Ar, and Ar/10%H2 atmospheres, respectively. The correlation length ξ increases with film thickness also with a power law according to ξ ∼ dfz with exponents z = 0.36, 0.44, and 0.57 for these three different gas atmospheres, respectively. A combination of local and non-local growth modes in 2 + 1 dimensions is discussed for the ITO growth in this work

  5. Transmission electron microscopy on early-stage tin oxide film morphology grown by atmospheric pressure chemical vapor deposition

    International Nuclear Information System (INIS)

    Nucleation and morphology development during the early stages of chemical vapor deposition (CVD) processes are believed to be of major importance for the overall film properties. Here, the authors have investigated the nucleation of tin oxide films, comparing different tin precursors (tin tetrachloride (TTC) and monobutyl tin trichloride (MBTC)) and focusing on the effect of methanol addition on the film morphology. Employing electron transparent silicon oxide membranes as substrates and combining transmission electron microscopy (TEM), scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS) analysis on the same set of samples, we describe a detailed picture of nucleation behavior and film growth during early stages of film formation. Our main conclusion is that methanol addition during deposition acts as surfactant, lowering the surface energy of the substrate and resulting in a higher nucleation grain density. Based on these results, we propose a film growth model based on surface energy to explain morphology differences in tin oxide films resulting from methanol addition.

  6. Atmospheric-Pressure DBD Cold Plasma for Preparation of High Active Au/P25 Catalysts for Low-Temperature CO Oxidation

    Science.gov (United States)

    Di, Lanbo; Zhan, Zhibin; Zhang, Xiuling; Qi, Bin; Xu, Weijie

    2016-05-01

    Cold plasma generated by dielectric barrier discharge (DBD) at atmospheric pressure was adopted for preparation of commercial TiO2 Degussa P25 supported Au catalysts (Au/P25-P) with the assistance of the deposition-precipitation procedure. The influences of the plasma reduction time and calcination on the performance of the Au/P25-P catalysts were investigated. CO oxidation was performed to investigate the catalytic activity of the Au/P25 catalysts. The results show that DBD cold plasma for the fabrication of Au/P25-P catalysts is a fast process, and Au/P25-P (4 min) exhibited the highest CO oxidation activity due to the complete reduction of Au compounds and less consumption of oxygen vacancies. In order to form more oxygen vacancies active species, Au/P25-P was calcined to obtain Au/P25-PC catalysts. Interestingly, Au/P25-PC exhibited the highest activity for CO oxidation among the Au/P25 samples. The results of transmission electron microscopy (TEM) indicated that the smaller size and high distribution of Au nanoparticles are the mean reasons for a high performance of Au/P25-PC. Atmospheric-pressure DBD cold plasma was proved to be of great efficiency in preparing high performance supported Au catalysts. supported by National Natural Science Foundation of China (Nos. 11505019, 21173028), the Science and Technology Research Project of Liaoning Provincial Education Department (No. L2013464), the Scientific Research Foundation for the Doctor of Liaoning Province (No. 20131004), and the Dalian Jinzhou New District Science and Technology Plan Project (No. KJCX-ZTPY-2014-0001)

  7. Atmospheric chemistry of (CF3)2C=CH2: OH radicals, Cl atoms and O3 rate coefficients, oxidation end-products and IR spectra.

    Science.gov (United States)

    Papadimitriou, Vassileios C; Spitieri, Christina S; Papagiannakopoulos, Panos; Cazaunau, Mathieu; Lendar, Maria; Daële, Véronique; Mellouki, Abdelwahid

    2015-10-14

    The rate coefficients for the gas phase reactions of OH radicals, k1, Cl atoms, k2, and O3, k3, with 3,3,3-trifluoro-2(trifluoromethyl)-1-propene ((CF3)2C=CH2, hexafluoroisobutylene, HFIB) were determined at room temperature and atmospheric pressure employing the relative rate method and using two atmospheric simulation chambers and a static photochemical reactor. OH and Cl rate coefficients obtained by both techniques were indistinguishable, within experimental precision, and the average values were k1 = (7.82 ± 0.55) × 10(-13) cm(3) molecule(-1) s(-1) and k2 = (3.45 ± 0.24) × 10(-11) cm(3) molecule(-1) s(-1), respectively. The quoted uncertainties are at 95% level of confidence and include the estimated systematic uncertainties. An upper limit for the O3 rate coefficient was determined to be k3 global warming potential (GWP) calculations, radiative efficiency (RE) was determined from the measured IR absorption cross-sections and treating HFIB both as long (LLC) and short (SLC) lived compounds, including estimated lifetime dependent factors in the SLC case. The HFIB lifetime was estimated from kinetic measurements considering merely the OH reaction, τOH = 14.8 days and including both OH and Cl chemistry, τeff = 10.3 days. Therefore, GWP(HFIB,OH) and GWP(HFIB,eff) were estimated to be 4.1 (LLC) and 0.6 (SLC), as well as 2.8 (LLC) and 0.3 (SLC) for a hundred year time horizon. Moreover, the estimated photochemical ozone creation potential (ε(POCP)) of HFIB was calculated to be 4.60. Finally, HCHO and (CF3)2C(O) were identified as final oxidation products in both OH- and Cl-initiated oxidation, while HC(O)Cl was additionally observed in the Cl-initiated oxidation. PMID:26372403

  8. Atmospheric Photochemistry

    Science.gov (United States)

    Massey, Harrie; Potter, A. E.

    1961-01-01

    The upper atmosphere offers a vast photochemical laboratory free from solid surfaces, so all reactions take place in the gaseous phase. At 30 km altitude the pressure has fallen to about one-hundredth of that at ground level, and we shall, rather arbitrarily, regard the upper atmosphere as beginning at that height. By a little less than 100 km the pressure has fallen to 10(exp -3) mm Hg and is decreasing by a power of ten for every 15 km increase in altitude. Essentially we are concerned then with the photochemistry of a nitrogen-oxygen mixture under low-pressure conditions in which photo-ionization, as well as photodissociation, plays an important part. Account must also be taken of the presence of rare constituents, such as water vapour and its decomposition products, including particularly hydroxyl, oxides of carbon, methane and, strangely enough, sodium, lithium and calcium. Many curious and unfamiliar reactions occur in the upper atmosphere. Some of them are luminescent, causing the atmosphere to emit a dim light called the airglow. Others, between gaseous ions and neutral molecules, are almost a complete mystery at this time. Similar interesting phenomena must occur in other planetary atmospheres, and they might be predicted if sufficient chemical information were available.

  9. Experimentation and simulation of tin oxide deposition on glass based on the SnCl4 hydrolysis in an in-line atmospheric pressure chemical vapor deposition reactor

    International Nuclear Information System (INIS)

    Tin oxide thin films were deposited on glass substrates in an in-line atmospheric pressure chemical vapor deposition reactor under various conditions, which were numerically simulated using a commercial package. A soda-lime glass sheet was used as a deposition substrate, and SnCl4 and H2O in gas phase were separately supplied as the precursor and the oxidizer, respectively. By assuming that the main chemical reactions followed the Rideal–Eley mechanism, the experimentally determined deposition rates were fitted to obtain the reaction factors needed to describe the deposition process. The role of barrier gas injection for minimizing unwanted surface reaction or particle generation inside of the reactor, and not on the target (glass backplane itself) has been elucidated. Furthermore, the optimal operating conditions for the deposition on glass with the additives such as CH3OH and HF have been investigated. - Highlights: • Tin oxide deposition on glass based on the SnCl4 hydrolysis in an in-line reactor • Simulations using Rideal–Eley mechanism were compared to experimental observations. • Results: activation energy—79.3 kJ/mol and frequency factor—1.93 × 1010 m4/kmol·s • Influences of additives on transmittances, hazes, and electrical resistivities

  10. Development of a detailed chemical mechanism (MCMv3.1 for the atmospheric oxidation of aromatic hydrocarbons

    Directory of Open Access Journals (Sweden)

    C. Bloss

    2004-09-01

    Full Text Available The Master Chemical Mechanism has been updated from MCMv3 to MCMv3.1 in order to take into account recent improvements in the understanding of aromatic photo-oxidation. Newly available kinetic and product data from the literature has been incorporated into the mechanism. In particular, the degradation mechanisms for hydroxyarenes have been revised following the observation of high yields of ring-retained products, and product studies of aromatic oxidation under relatively low NOx conditions have provided new information on the branching ratios to first generation products. Experiments have been carried out at the European Photoreactor (EUPHORE to investigate key subsets of the toluene system. These results have been used to test our understanding of toluene oxidation, and where possible, refine the degradation mechanisms. The evaluation of MCMv3 and MCMv3.1 using data on benzene, toluene, p-xylene and 1,3,5-trimethylbenzene photosmog systems is described in a companion paper, and significant model shortcomings are identified. Ideas for additional modifications to the mechanisms, and for future experiments to further our knowledge of the details of aromatic photo-oxidation are discussed.

  11. Development of a detailed chemical mechanism (MCMv3.1 for the atmospheric oxidation of aromatic hydrocarbons

    Directory of Open Access Journals (Sweden)

    C. Bloss

    2005-01-01

    Full Text Available The Master Chemical Mechanism has been updated from MCMv3 to MCMv3.1 in order to take into account recent improvements in the understanding of aromatic photo-oxidation. Newly available kinetic and product data from the literature have been incorporated into the mechanism. In particular, the degradation mechanisms for hydroxyarenes have been revised following the observation of high yields of ring-retained products, and product studies of aromatic oxidation under relatively low NOx conditions have provided new information on the branching ratios to first generation products. Experiments have been carried out at the European Photoreactor (EUPHORE to investigate key subsets of the toluene system. These results have been used to test our understanding of toluene oxidation, and, where possible, refine the degradation mechanisms. The evaluation of MCMv3 and MCMv3.1 using data on benzene, toluene, p-xylene and 1,3,5-trimethylbenzene photosmog systems is described in a companion paper, and significant model shortcomings are identified. Ideas for additional modifications to the mechanisms, and for future experiments to further our knowledge of the details of aromatic photo-oxidation are discussed.

  12. Effect of high-oxygen atmosphere packaging on oxidative stability and sensory quality of two chicken muscles during chill storage

    DEFF Research Database (Denmark)

    Jongberg, Sisse; Wen, Jinzhu; Tørngren, Mari Ann;

    2014-01-01

    of secondary lipid oxidation products. However, while breast stored in MAP-O clearly scored lower in tenderness and higher in rancidity compared to breast in non-oxygen storage, the effect of MAP-O for the sensory quality of thigh was negligible. These results show that thigh is more suitable for storage...

  13. Induced apoptosis in melanocytes cancer cell and oxidation in biomolecules through deuterium oxide generated from atmospheric pressure non-thermal plasma jet

    OpenAIRE

    Kumar, Naresh; Attri, Pankaj; Yadav, Dharmendra Kumar; Choi, Jinsung; Choi, Eun Ha; Uhm, Han Sup

    2014-01-01

    Recently, atmospheric-pressure non-thermal plasma-jets (APPJ) are being for the cancer treatment. However, APPJ still has drawbacks such as efficiency and rise in temperature after treatment. So, in this work, a synergetic agent D2O vapour is attached to APPJ which not only increase the efficiency of plasma source against cancer treatment, but also controlled the temperature during the treatment. OD generated by the combination of D2O + N2 plasma helped in enhancing the efficiency of APPJ. We...

  14. Flame spray synthesis under a non-oxidizing atmosphere: Preparation of metallic bismuth nanoparticles and nanocrystalline bulk bismuth metal

    Energy Technology Data Exchange (ETDEWEB)

    Grass, Robert N.; Stark, Wendelin J. [Institute for Chemical and Bioengineering, ETH Zuerich (Switzerland)], E-mail: wendelin.stark@chem.ethz.ch

    2006-10-15

    Metallic bismuth nanoparticles of over 98% purity were prepared by a modified flame spray synthesis method in an inert atmosphere by oxygen-deficient combustion of a bismuth-carboxylate based precursor. The samples were characterized by X-ray diffraction, thermal analysis and scanning electron microscopy confirming the formation of pure, crystalline metallic bismuth nanoparticles. Compression of the as-prepared powder resulted in highly dense, nanocrystalline pills with strong electrical conductivity and bright metallic gloss.

  15. Latitudinal and Altitudinal Distribution of Carbon Dioxide, Halocarbons, Nitrous Oxide, Methane, Carbon Monoxide and Hydroxyl in the Atmosphere

    OpenAIRE

    Kroeze, C.

    1992-01-01

    Due to human activities, atmospheric concentrations of several gases have been increasing during the past century. Some of these gases are so-called greenhouse gases and play an important role in the earth's climate. Increasing concentrations of greenhouse gases may ultimately result in global climate change. In order to investigate regional effects of the enhanced greenhouse effect, 1- to 3-dimensional computer simulation models are being developed. For the calculation of radiative transfer ...

  16. Investigation of the influence of inert and oxidizing atmospheres on the efficiency of decomposition of waste printed circuit boards (WPCBs)

    Science.gov (United States)

    Kumari, Anjan; Jha, Manis Kumar; Singh, Rajendra Prasad; Ranganathan, S.

    2016-08-01

    Thermo-gravimetry was used for studying the influence of the furnace atmosphere during the pyrolysis waste circuit boards (WPCBs). Pyrolysis in argon atmosphere resulted in a continuous decrease of mass of the sample. Rapid mass loss occurred at about 573 K. Heating the WPCBs in air and oxygen atmospheres resulted in an increase in the mass of the sample in the early stages until rapid mass loss occurred at about 573 K. When pyrolysis of larger sample mass (about 5 g each) was carried out in tubular furnace, about 20.43 % mass loss was observed during the pyrolysis of WPCBs in a flowing stream of argon at 548 K during a period of 4 min. On the other hand, a maximum of about 2.26 % mass loss was recorded when the WPCBs were heated at about 600 K for the same time interval in the still air. The mass transfer during the pyrolysis of WPCBs in flowing stream of inert gas was also modeled. It is found that controlling the flow rate of inert gas and the geometry of the equipment can enhance the rate of mass loss significantly.

  17. Atmospheric fate of OH initiated oxidation of terpenes. Reaction mechanism of alpha-pinene degradation and secondary organic aerosol formation.

    Science.gov (United States)

    Librando, Vito; Tringali, Giuseppe

    2005-05-01

    This paper studies the reaction products of alpha-pinene, beta-pinene, sabinene, 3-carene and limonene with OH radicals and of alpha-pinene with ozone using FT-IR spectroscopy for measuring gas phase products and HPLC-MS-MS to measure products in the aerosol phase. These techniques were used to investigate the secondary organic aerosol (SOA) formation from the terpenes. The gas phase reaction products were all quantified using reference compounds. At low terpene concentrations (0.9-2.1 ppm), the molar yields of gas phase reaction products were: HCHO 16-92%, HCOOH 10-54% (OH source: H2O2, 6-25 ppm); HCHO 127-148%, HCOOH 4-6% (OH source: CH3ONO, 5-8 ppm). At high terpene concentrations (4.1-13.2 ppm) the results were: HCHO 9-27%, HCOOH 15-23%, CH3(CO)CH3 0-14%, CH3COOH 0-5%, nopinone 24% (only from beta-pinene oxidation), limona ketone 61% (only from limonene oxidation), pinonaldehyde was identified during alpha-pinene degradation (OH source H2O2, 23-30 ppm); HCHO 76-183%, HCOOH 12-15%, CH3(CO)CH3 0-12%, nopinone 17% (from beta-pinene oxidation), limona ketone 48% (from limonene oxidation), pinonaldehyde was identified during alpha-pinene degradation (OH source CH3ONO, 14-16 ppm). Pinic acid, pinonic acid, limonic acid, limoninic acid, 3-caric acid, 3-caronic acid and sabinic acid were identified in the aerosol phase. On the basis of these results, we propose a formation mechanism for pinonic and pinic acid in the aerosol phase explaining how degradation products could influence SOA formation and growth in the troposphere.

  18. Methane oxidation in soil profiles of Dutch and Finnish coniferous forests with different soil texture and atmospheric nitrogen deposition

    NARCIS (Netherlands)

    Saari, A.; Martikainen, P.J.; Ferm, A.; Ruuskanen, J.; Boer, W. de; Troelstra, S.R.; Laanbroek, H.J.

    1997-01-01

    We studied methane oxidation capacity in soil profiles of Dutch and Finnish coniferous forests. The Finnish sites (n = 9) had nitrogen depositions from 3 to 36 kg N ha⁻¹ a⁻¹. The deposition of N on the Dutch sites (n = 13) was higher ranging from 50 to 92 kg N ha⁻¹ a⁻¹. The Dutch sites had also lime

  19. Influence of thermal treatment in N{sub 2} atmosphere on chemical, microstructural and optical properties of indium tin oxide and nitrogen doped indium tin oxide rf-sputtered thin films

    Energy Technology Data Exchange (ETDEWEB)

    Stroescu, H.; Anastasescu, M.; Preda, S.; Nicolescu, M.; Stoica, M. [Institute of Physical Chemistry “Ilie Murgulescu” of the Romanian Academy, Spl. Independentei 202, 060021 Bucharest (Romania); Stefan, N. [National Institute for Lasers, Plasma and Radiation Physics, Atomistilor 409, RO-77125, Bucharest-Magurele (Romania); Kampylafka, V.; Aperathitis, E. [FORTH-IESL, Crete (Greece); Modreanu, M. [Tyndall National Institute, University College Cork, Cork (Ireland); Zaharescu, M. [Institute of Physical Chemistry “Ilie Murgulescu” of the Romanian Academy, Spl. Independentei 202, 060021 Bucharest (Romania); Gartner, M., E-mail: mgartner@icf.ro [Institute of Physical Chemistry “Ilie Murgulescu” of the Romanian Academy, Spl. Independentei 202, 060021 Bucharest (Romania)

    2013-08-31

    We report the influence of the normal thermal treatment (TT) and of rapid thermal annealing (RTA) on the microstructural, optical and electrical properties of indium tin oxide (ITO) and nitrogen doped indium tin oxide (ITO:N) thin films. The TT was carried out for 1 h at 400 °C and the RTA for 1 min up to 400 °C, both in N{sub 2} atmosphere. The ITO and ITO:N films were deposited by reactive sputtering in Argon, and respectively Nitrogen plasma, on Si with (100) and (111) orientation. The present study brings data about the microstructural and optical properties of ITO thin films with thicknesses around 300–400 nm. Atomic Force Microscopy analysis showed the formation of continuous and homogeneous films, fully covered by quasi-spherical shaped particles, with higher roughness values on Si(100) as compared to Si(111). Spectroscopic ellipsometry allowed the determination of film thickness, optical band gap as well as of the dispersion curves of n and k optical constants. X-ray diffraction analysis revealed the presence of diffraction peaks corresponding to the same nominal bulk composition of ITO, but with different intensities and preferential orientation depending on the substrate, atmosphere of deposition and type of thermal treatment. - Highlights: ► Stability of the films can be monitored by experimental ellipsometric spectra. ► The refractive index of indium tin oxide film on 0.3–30 μm range is reported. ► Si(100) substrate induces rougher film surfaces than Si(111). ► Rapid thermal annealing and normal thermal treatment lead to stable conductive film. ► The samples have a higher preferential orientation after rapid thermal annealing.

  20. Atmospheric and Aqueous Deposition of Polycrystalline Metal Oxides Using Mist-CVD for Highly Efficient Inverted Polymer Solar Cells.

    Science.gov (United States)

    Zhu, Xiaodan; Kawaharamura, Toshiyuki; Stieg, Adam Z; Biswas, Chandan; Li, Lu; Ma, Zhu; Zurbuchen, Mark A; Pei, Qibing; Wang, Kang L

    2015-08-12

    Large scale, cost-effective processing of metal oxide thin films is critical for the fabrication of many novel thin film electronics. To date, however, most of the reported solution-based techniques require either extended thermal anneals or additional synthetic steps. Here we report mist chemical vapor deposition as a solution-based, readily scalable, and open-air method to produce high-quality polycrystalline metal oxide thin films. Continuous, smooth, and conformal deposition of metal oxide thin films is achieved by tuning the solvent chemistry of Leidenfrost droplets to promote finer control over the surface-local dissociation process of the atomized zinc-bearing precursors. We demonstrate the deposited ZnO as highly efficient electron transport layers for inverted polymer solar cells to show the power of the approach. A highest efficiency of 8.7% is achieved with a fill factor of 73%, comparable to that of conventional so-gel ZnO, which serves as an indication of the efficient vertical transport and electron collection achievable using this material. PMID:26146797

  1. Comparison of nitrous oxide (N2O) analyzers for high-precision measurements of atmospheric mole fractions

    Science.gov (United States)

    Lebegue, B.; Schmidt, M.; Ramonet, M.; Wastine, B.; Yver Kwok, C.; Laurent, O.; Belviso, S.; Guemri, A.; Philippon, C.; Smith, J.; Conil, S.; Jost, H. J.; Crosson, E. R.

    2015-10-01

    Over the last few decades, in-situ measurements of atmospheric N2O mole fractions have been performed using gas chromatographs (GCs) equipped with electron capture detectors (ECDs). When trying to meet the World Meteorological Organization's (WMO) quality goal, this technique becomes very challenging as the detectors are highly non-linear and the GCs at remote stations require a considerable amount of maintenance by qualified technicians to maintain good short-term and long-term repeatability. With more robust optical spectrometers being now available for N2O measurements, we aim to identify a robust and stable analyzer that can be integrated into atmospheric monitoring networks, such as the Integrated Carbon Observation System (ICOS). In this study, we tested seven analyzers that were developed and commercialized from five different companies and compared the results with established techniques. Each instrument was characterized during a time period of approximately eight weeks. The test protocols included the characterization of the short-term and long-term repeatability, drift, temperature dependence, linearity and sensitivity to water vapor. During the test period, ambient air measurements were compared under field conditions at the Gif-sur-Yvette station. All of the analyzers showed a standard deviation better than 0.1 ppb for the 10 min averages. Some analyzers would benefit from improvements in temperature stability to reduce the instrument drift, which could then help in reducing the frequency of calibrations. For most instruments, the water vapor correction algorithms applied by companies are not sufficient for high-precision atmospheric measurements, which results in the need to dry the ambient air prior to analysis.

  2. Degradation of polyethylene induced by plasma in oxidizing atmospheres; Degradacion de polietileno inducido por plasma en atmosferas oxidantes

    Energy Technology Data Exchange (ETDEWEB)

    Colin, E.; Olayo, M.G.; Cruz, G.J. [Facultad de Quimica, UAEM, Av. Tollocan y Colon, 50000 Toluca (Mexico)

    2002-07-01

    The garbage of polyethylene is not easily degradable in normal environmental conditions . The indiscriminate use of this polymer and the enormous quantity of garbage which is generated carries a damage to the environment due to its long life as waste. The objective of this work is to study the conditions in which can be carried out the degradation of polyethylene. A form of accelerating the degradation is exposing it to plasma with reactive atmospheres. In this work a study of surface modification of polyethylene by plasmas with discharges of direct current of oxygen and nitrogen is presented. (Author)

  3. The role of oxygen and surface reactions in the deposition of silicon oxide like films from HMDSO at atmospheric pressure

    OpenAIRE

    Reuter, R; Rügner, K.; Ellerweg, D.; Arcos, T. de los; von Keudell, A.; Benedikt, J

    2011-01-01

    The deposition of thin SiO$_x$C$_y$H$_z$ or SiO$_x$H$_y$ films by means of atmospheric pressure microplasma jets with admixture of Hexamethyldisiloxane (HMDSO) and oxygen and the role of surface reactions in film growth are investigated. Two types of microplasma jets, one with a planar electrodes and operated in helium gas and the other one with a coaxial geometry operated in argon, are used to study the deposition process. The growth rate of the film and the carbon-content in the film are me...

  4. Atmospheric carbon dioxide and its stable isotope ratios, methane, carbon monoxide, nitrous oxide and hydrogen from Shetland Isles

    Science.gov (United States)

    Francey, R. J.; Steele, L. P.; Langenfelds, R. L.; Allison, C. E.; Cooper, L. N.; Dunse, B. L.; Bell, B. G.; Murray, T. D.; Tait, H. S.; Thompson, L.; Masarie, K. A.

    Since November 1992, 0.5 l glass flasks have been filled approximately monthly with dry marine air from Shetland Isles, Scotland (60.2°N, 1.2°W) and transported to CSIRO, Australia for analyses. The Shetland site is part of a CSIRO global flask network with 10-12 sites, anchored to continuous high precision in situ measurements made at the Australian Cape Grim Baseline Station (40.7°S, 144.7°E), a primary station in the Global Atmosphere Watch programme (GAW) coordinated by the World Meteorological Organisation. The methodology is summarised, and Shetland results for CO 2, CH 4, N 2O, CO, H 2 and δ13C, δ18O of CO 2 presented for the period 1992-1996. We compare data to available results from surrounding stations of the NOAA cooperative network (in particular Mace Head, Ireland, 53.3°N, 9.9°W), and address issues of both trace species intercalibration and atmospheric spatial gradients. While considerable uniformity of trace-gas composition is evident in oceanic air over a 13° range of latitude, nevertheless anomalies in CO 2 concentration and isotopic composition are suggested in samples representing air to the west of Shetland. The potential for remotely monitoring integrated emissions from northern Europe is also identified.

  5. Microbial ecology of á-Proteobacteria ammonia-oxidizers along a concentration gradient of dry atmospheric nitrogen deposition in the San Bernadino Mountain Range.

    Science.gov (United States)

    Jordan, F. L.; Fenn, M. E.; Stein, L. Y.

    2002-12-01

    The fate of atmospherically-deposited nitrogen from industrial pollution is of major concern in the montane ecosystems bordering the South Coast California Air Basin. Nitrogen deposition rates in the more exposed regions of the San Bernardino Mountains (SBM) are among the highest in North America often exceeding 40 kg ha-1 year-1 in throughfall deposition of nitrate and ammonium (Fenn and Poth, 1999). Forest ecosystems with elevated N deposition generally exhibit elevated accumulation of soil nitrate, leaching and runoff, elevated emissions of nitrogenous gases, increased nitrification, and decreased litter decomposition rates. The role of nitrifying microbial populations, especially those taxonomically associated with the beta-Proteobacteria ammonia-oxidizers (AOB), will provide insight into nitrogen-cycling in these extremely N-saturated environments. Using 16S ribosomal DNA-based molecular techniques (16S rDNA clone library construction and Restriction Fragment Length Polymorphism), we are comparing AOB community diversity at 3 different locations along a natural atmospheric N-deposition concentration gradient in the SBM: from high at Camp Paviaka (CP), medium at Strawberry Peak (SP) to low at Dogwood (DW). As observed for wet N-deposition systems on the east coast, we hypothesized a negative correlation between AOB community diversity, abundance and function with nitrogen loading in the dry N deposition system of SBM. Nitrification potentials determined for the 3 sites along the N-deposition gradient were in the order of CP less than SP less than DW. Preliminary results indicate no correlation between diversity of AOB and increased nitrogen loading. Shannon-Weiner diversity indices calculated for ammonia-oxidizer RFLP group units were 2.22, 2.66 and 1.80 for CP, SP and DW, respectively.

  6. Size effects in the thermal conductivity of gallium oxide (β-Ga2O3) films grown via open-atmosphere annealing of gallium nitride

    Science.gov (United States)

    Szwejkowski, Chester J.; Creange, Nicole C.; Sun, Kai; Giri, Ashutosh; Donovan, Brian F.; Constantin, Costel; Hopkins, Patrick E.

    2015-02-01

    Gallium nitride (GaN) is a widely used semiconductor for high frequency and high power devices due to of its unique electrical properties: a wide band gap, high breakdown field, and high electron mobility. However, thermal management has become a limiting factor regarding efficiency, lifetime, and advancement of GaN devices and GaN-based applications. In this work, we study the thermal conductivity of beta-phase gallium oxide (β-Ga2O3) thin films, a component of typical gate oxides used in such devices. We use time domain thermoreflectance to measure the thermal conductivity of a variety of polycrystalline β-Ga2O3 films of different thicknesses grown via open atmosphere annealing of the surfaces of GaN films on sapphire substrates. We show that the measured effective thermal conductivity of these β-Ga2O3 films can span 1.5 orders of magnitude, increasing with an increased film thickness, which is indicative of the relatively large intrinsic thermal conductivity of the β-Ga2O3 grown via this technique (8.8 ± 3.4 W m-1 K-1) and large mean free paths compared to typical gate dielectrics commonly used in GaN device contacts. By conducting time domain thermoreflectance (TDTR) measurements with different metal transducers (Al, Au, and Au with a Ti wetting layer), we attribute this variation in effective thermal conductivity to a combination of size effects in the β-Ga2O3 film resulting from phonon scattering at the β-Ga2O3/GaN interface and thermal transport across the β-Ga2O3/GaN interface. The measured thermal properties of open atmosphere-grown β-Ga2O3 and its interface with GaN set the stage for thermal engineering of gate contacts in high frequency GaN-based devices.

  7. Shrinking of silicon nanocrystals embedded in an amorphous silicon oxide matrix during rapid thermal annealing in a forming gas atmosphere

    Science.gov (United States)

    van Sebille, M.; Fusi, A.; Xie, L.; Ali, H.; van Swaaij, R. A. C. M. M.; Leifer, K.; Zeman, M.

    2016-09-01

    We report the effect of hydrogen on the crystallization process of silicon nanocrystals embedded in a silicon oxide matrix. We show that hydrogen gas during annealing leads to a lower sub-band gap absorption, indicating passivation of defects created during annealing. Samples annealed in pure nitrogen show expected trends according to crystallization theory. Samples annealed in forming gas, however, deviate from this trend. Their crystallinity decreases for increased annealing time. Furthermore, we observe a decrease in the mean nanocrystal size and the size distribution broadens, indicating that hydrogen causes a size reduction of the silicon nanocrystals.

  8. UV absorption cross sections of nitrous oxide (N2O and carbon tetrachloride (CCl4 between 210 and 350 K and the atmospheric implications

    Directory of Open Access Journals (Sweden)

    C. H. Jackman

    2010-07-01

    Full Text Available Absorption cross sections of nitrous oxide (N2O and carbon tetrachloride (CCl4 are reported at five atomic UV lines (184.95, 202.548, 206.200, 213.857, and 228.8 nm at temperatures in the range 210–350 K. In addition, UV absorption spectra of CCl4 are reported between 200–235 nm as a function of temperature (225–350 K. The results from this work are critically compared with results from earlier studies. For N2O, the present results are in good agreement with the current JPL recommendation enabling a reduction in the estimated uncertainty in the N2O atmospheric photolysis rate. For CCl4, the present cross section results are systematically greater than the current recommendation at the reduced temperatures most relevant to stratospheric photolysis. The new cross sections result in a 5–7% increase in the modeled CCl4 photolysis loss, and a slight decrease in the stratospheric lifetime, from 51 to 50 years, for present day conditions. The corresponding changes in modeled inorganic chlorine and ozone in the stratosphere are quite small. A CCl4 cross section parameterization for use in atmospheric model calculations is presented.

  9. UV absorption cross sections of nitrous oxide (N2O and carbon tetrachloride (CCl4 between 210 and 350 K and the atmospheric implications

    Directory of Open Access Journals (Sweden)

    C. H. Jackman

    2010-04-01

    Full Text Available Absorption cross sections of nitrous oxide (N2O and carbon tetrachloride (CCl4 are reported at five atomic UV lines (184.95, 202.548, 206.200, 213.857, and 228.8 nm at temperatures in the range 210–350 K. In addition, UV absorption spectra of CCl4 are reported between 200–235 nm as a function of temperature (225–350 K. The results from this work are critically compared with results from earlier studies. For N2O, the present results are in good agreement with the current JPL recommendation enabling a reduction in the estimated uncertainty in the N2O atmospheric photolysis rate. For CCl4, the present cross section results are systematically greater than the current recommendation at the reduced temperatures most relevant to stratospheric photolysis. The new cross sections result in a 5–7% increase in the modeled CCl4 photolysis loss, and a slight decrease in the stratospheric lifetime, from 51 to 50 years, for present day conditions. The corresponding changes in modeled inorganic chlorine and ozone in the stratosphere are quite small. A CCl4 cross section parameterization for use in atmospheric model calculations is presented.

  10. Deposition of silicon oxide like films from HMDSO by means of atmospheric pressure microplasma jets: Study of deposition mechanisms

    CERN Document Server

    Reuter, R; Ellerweg, D; Arcos, T de los; von Keudell, A; Benedikt, J

    2011-01-01

    The deposition of thin SiOxCyH or SiOxHy films by means of atmospheric pressure microplasma jets with Helium / Hexamethyldisiloxane (HMDSO / O2) mixtures and the role of surface reactions for the film growth have been investigated. The growth rate and the carbon-content in the film are measured as a function of the O2 and HMDSO mixture in the gas flow. Two types of microplasma jets, one with a planar and one with a coaxial geometry, are used to study the deposition process. The very localised deposition on and treatment of the surface gives the opportunity to separate deposition and treatment processes by applying two jets on a rotating substrate. The etching of carbon at the surface and the increasing HMDSO depletion leading to an increasing deposition rate are both induced by admixing oxygen. Carbon free films can be deposited, even without addition of oxygen, and the main loss channels for carbon are surface reactions.

  11. Tensile Strength and Oxide Analysis of Carbon Steel in Concrete Exposed in Atmospheric Environment for 53 Years

    Institute of Scientific and Technical Information of China (English)

    FENG Xingguo; LU Xiangyu; ZUO Yu; CHEN Da; SU Xiaodong

    2015-01-01

    The tensile strength of a corroded rebar in a 53-year-old concrete structure was studied. The microstructure of the metallic substrate, the fracture surface, and the corrosion product layers were investigated. Metallographic observation results showed that the carbon steel was constituted of ferrite and some pearlite. The tensile test results indicated that the corroded rebar presented low strength and elongation. In addition, the fracture surface of the rebar in the tensile test displayed dimple fracture behavior. The Raman spectroscopy results indicated that corrosion products at the general corrosion zone were obviously different from those at the localized corrosion zone. The rust layer at the general corrosion zone was composed of goethite (α-FeOOH), magnetite (Fe3O4), and hematite (α-Fe2O3), while that of the pitting zone was made of feroxyhyte (δ-FeOOH), goethite (α-FeOOH), and hematite (α-Fe2O3). However, the general tendencies that the corrosion products were constituted of a mix of oxides and hydroxides, the oxides mainly existed in the internal part and the hydroxides more presented in the external layer were observed.

  12. Reproductive toxicology of disinfection by-products.

    OpenAIRE

    Smith, M. K.; Zenick, H; George, E L

    1986-01-01

    The chronic exposure of large segments of the population to disinfected drinking water has necessitated an evaluation of the health effects of the by-products of the chlorination process. This paper reviews the available information concerning the reproductive consequences associated with exposure to disinfection by-products. Four groups of compounds are discussed: the trihalomethanes, in particular chloroform; the chlorinated phenols; chlorinated humic substances; and the haloacetonitriles. ...

  13. Ambient atmosphere-processable, printable Cu electrodes for flexible device applications: structural welding on a millisecond timescale of surface oxide-free Cu nanoparticles

    Science.gov (United States)

    Oh, Sang-Jin; Jo, Yejin; Lee, Eun Jung; Lee, Sun Sook; Kang, Young Hun; Jeon, Hye-Ji; Cho, Song Yun; Park, Jin-Seong; Seo, Yeong-Hui; Ryu, Beyong-Hwan; Choi, Youngmin; Jeong, Sunho

    2015-02-01

    Recently, various functional devices based on printing technologies have been of paramount interest, owing to their characteristic processing advantages along with excellent device performance. In particular, printable metallic electrodes have drawn attention in a variety of optoelectronic applications; however, research into printable metallic nanoparticles has been limited mainly to the case of an environmentally stable Ag phase. Despite its earth-abundance and highly conductive nature, the Cu phase, to date, has not been exploited as an ambient atmosphere-processable, printable material due to its critical oxidation problem in air. In this study, we demonstrate a facile route for generating highly conductive, flexible Cu electrodes in air by introducing the well-optimized photonic sintering at a time frame of 10-3 s, at which the photon energy, rather than conventional thermal energy, is instantly provided. It is elucidated here how the surface oxide-free, printed Cu particulate films undergo chemical structural/microstructural evolution depending on the instantly irradiated photon energy, and a successful demonstration is provided of large-area, flexible, printed Cu conductors on various substrates, including polyimide (PI), polyethersulfone (PES), polyethylene terephthalate (PET), and paper. The applicability of the resulting printed Cu electrodes is evaluated via implementation into both flexible capacitor devices and indium-gallium-zinc oxide (IGZO) flexible thin-film transistors.Recently, various functional devices based on printing technologies have been of paramount interest, owing to their characteristic processing advantages along with excellent device performance. In particular, printable metallic electrodes have drawn attention in a variety of optoelectronic applications; however, research into printable metallic nanoparticles has been limited mainly to the case of an environmentally stable Ag phase. Despite its earth-abundance and highly conductive

  14. Inductively coupled plasma torch efficiency at atmospheric pressure for organo-chlorine liquid waste removal: Chloroform destruction in oxidative conditions

    Energy Technology Data Exchange (ETDEWEB)

    Kamgang-Youbi, Georges, E-mail: kamyougeo@yahoo.fr [French Atomic Commission-CEA, Marcoule-DTCD/SCDV/LPIC, BP 17171, 30207 Bagnols-Sur-Cèze Cedex (France); Department of Inorganic Chemistry, The University of Yaounde I, P.O Box, 812 Yaounde (Cameroon); Poizot, Karine; Lemont, Florent [French Atomic Commission-CEA, Marcoule-DTCD/SCDV/LPIC, BP 17171, 30207 Bagnols-Sur-Cèze Cedex (France)

    2013-01-15

    Highlights: ► Inductively plasma torch is used for the decomposition of organochlorine molecule. ► We examine the impact of liquid water substitution by oxygen gas as oxidant. ► Complete and safe decomposition is achieved with the presence of oxygen. ► The energy efficiency and capabilities of process are better with O{sub 2} than H{sub 2}O. -- Abstract: The performance of a plasma reactor for the degradation of chlorinated hydrocarbon waste is reported. Chloroform was used as a target for a recently patented destruction process based using an inductive plasma torch. Liquid waste was directly injected axially into the argon plasma with a supplied power of ∼4 kW in the presence of oxygen as oxidant and carrier gas. Decomposition was performed at CHCl{sub 3} feed rates up to 400 g h{sup −1} with different oxygen/waste molar ratios, chloroform destruction was obtained with at least 99% efficiency and the energy efficiency reached 100 g kWh{sup −1}. The conversion end products were identified and assayed by online FTIR spectroscopy (CO{sub 2}, HCl and H{sub 2}O) and redox titration (Cl{sub 2}). Considering phosgene as representative of toxic compounds, only very small quantities of toxics were released (<1 g h{sup −1}) even with high waste feed rates. The experimental results were very close to the equilibrium composition predicted by thermodynamic calculations. At the bottom of the reactor, the chlorinated acids were successfully trapped in a scrubber and transformed into mineral salts, hence, only CO{sub 2} and H{sub 2}O have been found in the final off-gases composition.

  15. Quantification of carbon dioxide, methane, nitrous oxide, and chloroform emissions over Ireland from atmospheric observations at Mace Head

    International Nuclear Information System (INIS)

    Flux estimates of CO2, CH4, N2O and CHCl3 over Ireland are inferred from continuous atmospheric records of these species. We use radon-222 (222Rn) as a reference compound to estimate unknown sources of other species. The correlation between each species and 222Rn is calculated for a suite of diurnal events that have been selected in the Mace Head record over the period 1995-1997 to represent air masses exposed to sources over Ireland. We established data selection criteria based on 222Rn and 212Pb concentrations. We estimated flux densities of 12x103 kg CH4/km2/yr, 680 kg N2O/km2/yr and 20 kg CHCl3/km2/yr for CH4, N2O and CHCl3, respectively. We also inferred flux densities of 250x103 kg C/km2/yr for CO2 during wintertime, and of 760x103 kg C/km2/yr for CO2 during summer night-time. Our CH4 inferred flux compare well with the CORINAIR90 and CORNAIR94 inventories for Ireland. The N2O emission flux we inferred is close to the inventory value by CORINAIR90, but twice the inventory value by CORINAIR94 and EDGAR 2.0. This discrepancy may have been caused by the use of the revised 1996 IPCC guidelines for national greenhouse gas inventories in 1994, which include a new methodology for N2O emissions from agriculture. We carried out the first estimation of CHCl3 emission fluxes over Ireland. This estimation is 4 times larger than the CHCl3 emission fluxes measured close to the Mace Head station over peatlands. Our CHCl3 emission fluxes estimate is consistent with the interpretation of the same data by Ryall (personal communication, 2000), who obtained, using a Lagrangian atmospheric transport model, CHCl3 fluxes of 24±7 kg CHCl3/km2/yr. Our estimates of CO2 emission fluxes during summer night-time and wintertime are close to those estimated from inventories and to one biogeochemical model of heterotrophic respiration

  16. NATURAL ANTIOXIDANT INGREDIENT FROM BY-PRODUCTS OF FRUITS

    Directory of Open Access Journals (Sweden)

    G. S. El-Baroty

    2014-01-01

    used safely in the edible oil industry and cosmetics to delay its oxidation. It can be applied in other food industries as a natural antioxidant instead of synthetic antioxidants. Further study should be carried out to identify the predominant phenolics responsible for the antioxidant activity of by product extracts.

  17. Hemodynamic Changes Caused by Exposure of Animals with Acute Immobilization Stress to Continuous Terahertz Radiation with Frequencies equal to Absorption and Emission Frequencies of Nitrogen Oxide and Atmospheric Oxygen

    Directory of Open Access Journals (Sweden)

    Vyacheslav F. Kirichuk

    2012-12-01

    Full Text Available The aim was to study the effects of exposure of albino rats to continuous terahertz radiation with frequencies equal to absorption and emission frequencies of nitrogen oxide (150.176-150.664 GHz and atmospheric oxygen (129.0 ± 0.75 GHz during their immobilization stress on their blood flow rate. Methods – The group of 120 male non-pedigree albino rats with average weight of 180-220 g was chosen as a test subject. Simulation of hemodynamic disorders was achieved by incurring active immobilization stress. All rats were exposed to electromagnetic terahertz radiation equal to absorption and emission frequencies of nitrogen oxide (150.176-150.664 GHz and atmospheric oxygen (129.0 ± 0.75 GHz for 5, 15 and 30 minutes. Results – Experimental simulation of hemodynamic disorders during acute immobilization stress has shown that exposure to continuous terahertz radiation with frequencies equal to absorption and emission frequencies of nitrogen oxide (150.176-150.664 GHz and atmospheric oxygen (129.0 ± 0.75 GHz for 5, 15 and 30 minutes allows to revert post-stress hemodynamic changes in great vessels. Conclusion – This allows using terahertz electromagnetic radiation with frequencies equal to absorption and emission frequencies of nitrogen oxide (150.176-150.664 GHz and atmospheric oxygen (129.0 ± 0.75 GHz to treat hemodynamic disorders accompanying some of pathologic diseases.

  18. Control of substrate oxidation in MOD ceramic coating on low-activation ferritic steel with reduced-pressure atmosphere

    Energy Technology Data Exchange (ETDEWEB)

    Tanaka, Teruya, E-mail: teru@nifs.ac.jp; Muroga, Takeo

    2014-12-15

    Highlights: • A Cr{sub 2}O{sub 3} layer was produced on a ferritic steel substrate with a reduced-pressure. • The Cr{sub 2}O{sub 3} layer prevents further substrate oxidation in following coating process. • The Cr{sub 2}O{sub 3} layer has a function as a hydrogen permeation barrier. • A smooth MOD Er{sub 2}O{sub 3} coating was successfully made on the Cr{sub 2}O{sub 3} layer by dip coating. • The Cr{sub 2}O{sub 3} layer would enhance flexibility in MOD coating process and performances. - Abstract: An Er{sub 2}O{sub 3} ceramic coating fabricated using the metal–organic decomposition (MOD) method on a Cr{sub 2}O{sub 3}-covered low-activation ferritic steel JLF-1 substrate was examined to improve hydrogen permeation barrier performance of the coating. The Cr{sub 2}O{sub 3} layer was obtained before coating by heat treating the substrate at 700 °C under reduced pressures of <5 × 10{sup −3} Pa and 5 Pa. The Cr{sub 2}O{sub 3} layer was significantly stable even with heat treatment at 700 °C in air. This layer prevented further production of Fe{sub 2}O{sub 3}, which has been considered to degrade coating performance. An MOD Er{sub 2}O{sub 3} coating with a smooth surface was successfully obtained on a Cr{sub 2}O{sub 3}-covered JLF-1 substrate by dip coating followed by drying and baking. Preprocessing to obtain a Cr{sub 2}O{sub 3} layer would provide flexibility in the coating process for blanket components and ducts. Moreover, the Cr{sub 2}O{sub 3} layer suppressed hydrogen permeation through the JLF-1 substrate. While further optimization of the coating fabrication process is required, it would be possible to suppress hydrogen permeation significantly by multilayers of Cr{sub 2}O{sub 3} and MOD oxide ceramic.

  19. A laboratory study of the oxidation of non toxic Cr(III) to toxic Cr(VI) by OH• free radicals in simulated atmospheric water droplets conditions: Potential environmental impact

    International Nuclear Information System (INIS)

    Highlights: • Oxidation of non toxic Cr(III) to toxic Cr(VI) is a major environmental hazard. • oxidation by OH. free radicals generated by water radiolysis. • Oxidation is maximum at pH 4. • A mechanism is proposed. - Abstract: In atmospheric waters, oxidation of Cr(III) to Cr(VI) by OH• free radicals is a major environmental hazard since non-toxic species is transformed into toxic one. It is important to obtain some details concerning this oxidation reaction. In this study we simulated this oxidation by steady state radiolysis using 60Co radioactive source and pulse radiolysis technique using a 2.5 MeV van de Graaff electron accelerator and investigated its kinetics in the pH range 1 to 9. Our findings showed that the reaction was highly pH dependant with a maximum yield at pH 4. The electron transfer proceeds via an inner sphere mechanism with (i) formation of the [OH• –Cr(III)] adduct with an equilibrium constant of 2.34 × 104 mol−1 dm−3 then (ii) followed by an electron transfer from Cr(III) to OH• within the adduct with a rate constant of 2.51 × 104 s−1. The implication of this oxidation to atmospheric chromium contamination is discussed

  20. Anaerobic digestion of slaughterhouse by-products

    Energy Technology Data Exchange (ETDEWEB)

    Hejnfelt, Anette; Angelidaki, Irini [Department of Environmental Engineering, Technical University of Denmark, DTU, Building 113, DK-2800 Kgs. Lyngby (Denmark)

    2009-08-15

    Anaerobic digestion of animal by-products was investigated in batch and semi-continuously fed, reactor experiments at 55 C and for some experiments also at 37 C. Separate or mixed by-products from pigs were tested. The methane potential measured by batch assays for meat- and bone flour, fat, blood, hair, meat, ribs, raw waste were: 225, 497, 487, 561, 582, 575, 359, 619 dm{sup 3} kg{sup -1} respectively, corresponding to 50-100% of the calculated theoretical methane potential. Dilution of the by-products had a positive effect on the specific methane yield with the highest dilutions giving the best results. High concentrations of long-chain fatty acids and ammonia in the by-products were found to inhibit the biogas process at concentrations higher than 5 g lipids dm{sup -3} and 7 g N dm{sup -3} respectively. Pretreatment (pasteurization: 70 C, sterilization: 133 C), and alkali hydrolysis (NaOH) had no effect on achieved methane yields. Mesophilic digestion was more stable than thermophilic digestion, and higher methane yield was noticed at high waste concentrations. The lower yield at thermophilic temperature and high waste concentration was due to ammonia inhibition. Co-digestion of 5% pork by-products mixed with pig manure at 37 C showed 40% higher methane production compared to digestion of manure alone. (author)

  1. Tillage and Fertilizer Management Effects on Soil-Atmospheric Exchanges of Methane and Nitrous Oxide in a Corn Production System

    Directory of Open Access Journals (Sweden)

    Ermson Z. Nyakatawa

    2011-01-01

    Full Text Available Land application of poultry litter (PL presents an opportunity to improve soil productivity and disposal of poultry waste. We investigated methane (CH4 and nitrous oxide (N2O emissions from agricultural soil receiving PL and ammonium nitrate (AN fertilizers using surface (SA, soil incorporation (SI, and subsurface band (BA application methods in conventional (CT and no-tillage (NT systems on a Decatur silt loam soil in North Alabama. Plots under CT and NT were sinks of CH4 in spring, summer, and fall. In winter, the plots had net emissions of 3.32 and 4.24 g CH4 ha-1 day-1 in CT and NT systems, respectively. Plots which received AN were net emitters of CH4 and N2O, whereas plots which received PL were net sinks of CH4. Plots which received PL using SA or SI methods were net emitters of N2O, whereas under PL using BA application, the plots were net sinks of N2O. Our study indicates that using subsurface band application of PL was the most promising environmentally sustainable poultry waste application method for reducing CH4 and N2O emissions from agricultural soil in NT and CT corn production systems on the Decatur soil in north Alabama.

  2. Characterizations of arsenic-doped zinc oxide films produced by atmospheric metal-organic chemical vapor deposition

    International Nuclear Information System (INIS)

    p-type ZnO films were prepared by atmospheric metal-organic chemical vapor deposition technique using arsine (AsH3) as the doping source. The electrical and optical properties of arsenic-doped ZnO (ZnO:As) films fabricated at 450–600 °C with various AsH3 flow rates ranging from 8 to 21.34 μmol/min were analyzed and compared. Hall measurements indicate that stable p-type ZnO films with hole concentrations varying from 7.2 × 1015 to 5.8 × 1018 cm−3 could be obtained. Besides, low temperature (17 K) photoluminescence spectra of all ZnO:As films also demonstrate the dominance of the line related to the neutral acceptor-bound exciton. Moreover, the elemental identity and chemical bonding information for ZnO:As films were examined by X-ray photoelectron spectroscopy. Based on the results obtained, the effects of doping conditions on the mechanism responsible for the p-type conduction were studied. Conclusively, a simple technique to fabricate good-quality p-type ZnO films has been recognized in this work. Depositing the film at 550 °C with an AsH3 flow rate of 13.72 μmol/min is appropriate for producing hole concentrations on the order of 1017 cm−3 for it. Ultimately, by increasing the AsH3 flow rate to 21.34 μmol/min for doping and depositing the film at 600 °C, ZnO:As films with a hole concentration over 5 × 1018 cm−3 together with a mobility of 1.93 cm2V−1 s−1 and a resistivity of 0.494 ohm-cm can be achieved.

  3. Behaviour of Al2O3 scales on Fe-Al and Fe-Ni-Al alloys with small additions of titanium, zirconium, niobium and vanadium on thermal cycling and creep in oxidizing and carburizing atmospheres

    International Nuclear Information System (INIS)

    Aluminium as an alloying element in steels is beneficial for the formation of slow-growing oxide layers at high temperatures. Steels with aluminium as the oxide former are of interest for use in carburizing atmospheres with low O2 partial pressures, e.g. coal gasification or the high temperature nuclear reactor. The behaviour of Al2O3 layers on ferritic and austenitic steels with small additions of titanium, zirconium, niobium and vanadium was studied by measuring radiocarbon penetration in thermal cycling and creep experiments. The oxide layers on the ferritic steels adhered well and were compact with a high carburization resistance. In the creep tests on the austenitic alloys, cracking of the oxide layer and subsequent intergranular oxidation and carburization were observed. (orig.)

  4. Anaerobic digestion of slaughterhouse by-products

    DEFF Research Database (Denmark)

    Hejnfelt, Anette; Angelidaki, Irini

    2009-01-01

    hydrolysis (NaOH) had no effect on achieved methane yields. Mesophilic digestion was more stable than thermophilic digestion, and higher methane yield was noticed at high waste concentrations. The lower yield at thermophilic temperature and high waste concentration was due to ammonia inhibition. Co......Anaerobic digestion of animal by-products was investigated in batch and semi-continuously fed, reactor experiments at 55 degrees C and for some experiments also at 37 degrees C. Separate or mixed by-products from pigs were tested. The methane potential measured by batch assays for meat- and bone...... giving the best results. High concentrations of long-chain fatty acids and ammonia in the by-products were found to inhibit the biogas process at concentrations higher than 5 g lipids dm(-3) and 7 gN dm(-3) respectively. Pretreatment (pasteurization: 70 degrees C, sterilization: 133 degrees C, and alkali...

  5. Atmospheric oxidation of isoprene and 1,3-butadiene: influence of aerosol acidity and relative humidity on secondary organic aerosol

    Directory of Open Access Journals (Sweden)

    M. Lewandowski

    2014-11-01

    Full Text Available The effects of acidic seed aerosols on the formation of secondary organic aerosol (SOA have been examined in a number of previous studies, several of which have observed strong linear correlations between the aerosol acidity (measured as nmol H+ per m3 air sample volume and the percent change of secondary organic carbon (SOC. The measurements have used several precursor compounds representative of different classes of biogenic hydrocarbons including isoprene, monoterpenes, and sesquiterpenes. To date, isoprene has displayed the most pronounced increase in SOC, although few measurements have been conducted with anthropogenic hydrocarbons. In the present study, we examine several aspects of the effect of aerosol acidity on the secondary organic carbon formation from the photooxidation of 1,3-butadiene, as well as extending the previous analysis of isoprene. The photooxidation products measured in the absence and presence of acidic sulfate aerosols were generated either through photochemical oxidation of SO2 or by nebulizing mixtures of ammonium sulfate and sulfuric acid into a 14.5 m3 smog chamber system. The results showed that, like isoprene and β-caryophyllene, 1,3-butadiene SOC yields linearly correlate with increasing acidic sulfate aerosol. The observed acid sensitivity of 0.11% SOC increase per nmol m−3 increase in H+ was approximately a factor of three less than that measured for isoprene. The results also showed that the aerosol yield decreased with increasing humidity for both isoprene and 1,3-butadiene, although to different degrees. Increasing the absolute humidity from 2 to 12 g m−3 reduced the 1,3-butadiene yield by 45% and the isoprene yield by 85%.

  6. Mechanism of the hydroxy radical oxidation of methacryoyl peroxynitrate (MPAN) and its pathway toward secondary organic aerosol formation in the atmosphere

    Energy Technology Data Exchange (ETDEWEB)

    Nguyen, Tran B.; Bates, Kelvin H.; Crounse, J. D.; Schwantes, Rebecca H.; Zhang, Xuan; Kjaergaard, Henrik G.; Surratt, Jason D.; Lin, Peng; Laskin, Alexander; Seinfeld, John H.; Wennberg, P. O.

    2015-01-01

    Methacryoyl peroxynitrate (MPAN), the acylperoxyl nitrate of methacrolein, has been suggested to be an important secondary organic aerosol (SOA) precursor from isoprene oxidation. Yet, the mechanism by which MPAN produces SOA via reaction with the hydroxyl radical (OH) is unclear. We systematically evaluate three proposed mechanisms in controlled chamber experiments and provide the first experimental support for the theoretically-predicted lactone formation pathway from the MPAN + OH reaction, producing hydroxymethyl-methyl-α-lactone (HMML). The decomposition of the MPAN-OH adduct yields HMML + NO3 (~ 75%) and hydroxyacetone + CO + NO3 (~ 25%), out-competing its reaction with atmospheric oxygen. The production of other proposed SOA precursors, e.g., methacrylic acid epoxide (MAE), from MPAN and methacrolein are negligible (< 2 %). Furthermore, we show that the beta-alkenyl moiety of MPAN is critical for lactone formation. Alkyl radicals formed via OH abstraction nstead of addition are thermalized; thus, even if they are structurally identical to the MPAN-OH adduct, they do not decompose to HMML. The SOA formation from HMML, via polyaddition of the lactone to organic compounds, is close to unity under dry conditions. However, the SOA yield is sensitive to particle liquid water and solvated ions. In hydrated sulfate-containing particles, HMML reacts primarily with H2O and aqueous sulfate, producing monomeric 2-methylglyceric acid (2MGA) and the associated organosulfate. 2MGA, a tracer for isoprene SOA, is semivolatile and its volatility increases with decreasing pH in the aerosol water. Conditions that enhance the production of neutral 2MGA will suppress SOA mass from the HMML channel. Considering the liquid water content and pH ranges of ambient particles, MGA may exist largely as a gaseous compound in some parts of the atmosphere.

  7. Reaction products and mechanisms for the reaction of n-butyl vinyl ether with the oxidants OH and Cl: Atmospheric implications

    Science.gov (United States)

    Colmenar, Inmaculada; Martín, Pilar; Cabañas, Beatriz; Salgado, Sagrario; Tapia, Araceli; Martínez, Ernesto

    2015-12-01

    A reaction product study for the degradation of butyl vinyl ether (CH3(CH2)3OCHdbnd CH2) by reaction with chlorine atoms (Cl) and hydroxyl radicals (OH) has been carried out using Fourier Transform Infrared absorption spectroscopy (FTIR) and/or Gas Chromatography-Mass Spectrometry with a Time of Flight analyzer (GC-TOFMS). The rate coefficient for the reaction of butyl vinyl ether (BVE) with chlorine atoms has also been evaluated for the first time at room temperature (298 ± 2) K and atmospheric pressure (708 ± 8) Torr. The rate coefficient obtained was (9.9 ± 1.5) × 10-10 cm3 molecule-1 s-1 and this indicates the high reactivity of butyl vinyl ether with Cl atoms. However, this value may be affected by the dark reaction of BVE with Cl2. The results of a qualitative study of the Cl reaction show that the main oxidation products are butyl formate (CH3(CH2)3OC(O)H), butyl chloroacetate (CH3(CH2)3OC(O)CH2Cl and formyl chloride (HCOCl). Individual yields in the ranges ∼16-40% and 30-70% in the absence and presence of NOx, respectively, have been estimated for these products. In the OH reaction, butyl formate and formic acid were identified as the main products, with yields of around 50 and 20%, respectively. Based on the results of this work and a literature survey, the addition of OH radicals and Cl atoms at the terminal C atom of the double bond in CH3(CH2)3OCHdbnd CH2 has been proposed as the first step in the reaction mechanism for both of the studied oxidants. The tropospheric lifetime of butyl vinyl ether is very short and, as a consequence, it will be rapidly degraded and will only be involved in tropospheric chemistry at a local level. The degradation products of these reactions should be considered when evaluating the atmospheric impact.

  8. Effects on surface atmospheric photo-oxidants over Greece during the total solar eclipse event of 29 March 2006

    Directory of Open Access Journals (Sweden)

    P. Zanis

    2007-08-01

    Full Text Available This study investigates the effects of the total solar eclipse of 29 March 2006 on surface air-quality levels over Greece based on observations at a number of sites in conjunction with chemical box modelling and 3-D air-quality modelling. Emphasis is given on surface ozone and other photooxidants at four Greek sites Kastelorizo, Finokalia (Crete, Pallini (Athens and Thessaloniki, which are located at gradually increasing distances from the path of the eclipse totality and are characterized by different air pollution levels. The eclipse offered the opportunity to test our understanding of air pollution build-up and the response of the gas-phase chemistry of photo-oxidants during a photolytical perturbation using both a photochemical box model and a regional air-quality offline model based on the modeling system WRF/CAMx. At the relatively unpolluted sites of Kastelorizo and Finokalia no clear impact of the solar eclipse on surface O3, NO2 and NO concentrations can be deduced from the observations and model simulations as the calculated changes in net ozone production rates between eclipse and non eclipse conditions are rather small compared to the ozone variability and hence the solar eclipse effects on ozone can be easily masked by transport. At the polluted sites of Thessaloniki and Pallini, the solar eclipse effects on O3, NO2 and NO concentrations are clearly revealed from both the measurements and 3-D air-quality modeling with the net effect being a decrease in O3 and NO and an increase in NO2 as NO2 formed from the reaction of O3 with NO while at the same time NO2 is not efficiently photolysed. It is evident from the 3-D air quality modeling over Greece that the maximum effects of the eclipse on O3, NO2 and NO are reflected at the large urban agglomerations of Athens, and Thessaloniki where the maximum of the emissions

  9. Effects on surface atmospheric photo-oxidants over Greece during the total solar eclipse event of 29 March 2006

    Directory of Open Access Journals (Sweden)

    P. Zanis

    2007-12-01

    Full Text Available This study investigates the effects of the total solar eclipse of 29 March 2006 on surface air-quality levels over Greece based on observations at a number of sites in conjunction with chemical box modelling and 3-D air-quality modelling. Emphasis is given on surface ozone and other photooxidants at four Greek sites Kastelorizo, Finokalia (Crete, Pallini (Athens and Thessaloniki, which are located at gradually increasing distances from the path of the eclipse totality and are characterized by different air pollution levels. The eclipse offered the opportunity to test our understanding of air pollution build-up and the response of the gas-phase chemistry of photo-oxidants during a photolytical perturbation using both a photochemical box model and a regional air-quality offline model based on the modeling system WRF/CAMx. At the relatively unpolluted sites of Kastelorizo and Finokalia no clear signal of the solar eclipse on surface O3, NO2 and NO concentrations can be deduced from the observations while there is no correlation of observed O3, NO2 and NO with observed global radiation. The box and regional model simulations for the two relatively unpolluted sites indicate that the calculated changes in net ozone production rates between eclipse and non eclipse conditions are rather small compared to the observed short-term ozone variability. Furthermore the simulated ozone lifetime is in the range of a few days at these sites and hence the solar eclipse effects on ozone can be easily masked by local and regional transport. At the polluted sites of Thessaloniki and Pallini, the solar eclipse effects on O3, NO2 and NO concentrations are revealed from both the measurements and modeling with the net effect being a decrease in O3 and NO and an increase in NO2 as NO2 formed from the reaction of O3 with NO while at the same time NO2 is

  10. Oxidation of SO2 by stabilized Criegee intermediate (sCI radicals as a crucial source for atmospheric sulfuric acid concentrations

    Directory of Open Access Journals (Sweden)

    M. Boy

    2013-04-01

    Full Text Available The effect of increased reaction rates of stabilized Criegee intermediates (sCIs with SO2 to produce sulfuric acid is investigated using data from two different locations, SMEAR II, Hyytiälä, Finland, and Hohenpeissenberg, Germany. Results from MALTE, a zero-dimensional model, show that using previous values for the rate coefficients of sCI + SO2, the model underestimates gas phase H2SO4 by up to a factor of two when compared to measurements. Using the rate coefficients recently calculated by Mauldin et al. (2012 increases sulfuric acid by 30–40%. Increasing the rate coefficient for formaldehyde oxide (CH2OO with SO2 according to the values recommended by Welz et al. (2012 increases the H2SO4 yield by 3–6%. Taken together, these increases lead to the conclusion that, depending on their concentrations, the reaction of stabilized Criegee intermediates with SO2 could contribute as much as 33–46% to atmospheric sulfuric acid gas phase concentrations at ground level. Using the SMEAR II data, results from SOSA, a one-dimensional model, show that the contribution from sCI reactions to sulfuric acid production is most important in the canopy, where the concentrations of organic compounds are the highest, but can have significant effects on sulfuric acid concentrations up to 100 m. The recent findings that the reaction of sCI + SO2 is much faster than previously thought together with these results show that the inclusion of this new oxidation mechanism could be crucial in regional as well as global models.

  11. Valorization of food processing by-products

    NARCIS (Netherlands)

    Chandrasekaran, M.; Nout, M.J.R.; Sarkar, P.K.

    2012-01-01

    Biotechnology has immense potential for resolving environmental problems and augmenting food production. Particularly, it offers solutions for converting solid wastes into value-added items. In food processing industries that generate voluminous by-products and wastes, valorization can help offset g

  12. Atmospheric-Pressure Plasma Jet Processed Pt-Decorated Reduced Graphene Oxides for Counter-Electrodes of Dye-Sensitized Solar Cells

    Directory of Open Access Journals (Sweden)

    Ting-Hao Wan

    2016-10-01

    Full Text Available Ultrafast atmospheric-pressure plasma jet (APPJ processed Pt-decorated reduced graphene oxides (rGOs were used as counter-electrodes in dye-sensitized solar cells (DSSCs. Pastes containing rGO, ethyl cellulose, terpineol, and chloroplatinic acid were screen-printed and sintered by nitrogen dc-pulse APPJs. Pt nanodots were uniformly distributed on the rGO flakes. When using Pt-decorated rGOs as the counter electrodes of DSSCs, the efficiency of the DSSC first increased and then decreased as the APPJ processing time increased. Nitrogen APPJs can effectively remove organic binders and can reduce chloroplatinic acid to Pt, thereby improving the efficiency of DSSCs. However, over-calcination by APPJ can damage the graphenes and degrade the DSSCs. The addition of Pt mainly improves the fill factor, which thereby increases the efficiency of DSSCs. The optimized APPJ processing time was merely 9 s owing to the vigorous interaction among the rGOs, chloroplatinic acid and nitrogen APPJs.

  13. Capture of atmospheric CO2 into (BiO)2CO3/graphene or graphene oxide nanocomposites with enhanced photocatalytic performance

    Science.gov (United States)

    Zhang, Wendong; Dong, Fan; Zhang, Wei

    2015-12-01

    Self-assembly of (BiO)2CO3 nanoflakes on graphene (Ge) and graphene oxide (GO) nanosheets, as an effective strategy to improve the photocatalytic performance of two-dimensional (2D) nanostructured materials, were realized by a one-pot efficient capture of atmospheric CO2 at room temperature. The as-synthesized samples were characterized by XRD, SEM, TEM, XPS, UV-vis DRS, Time-resolved ns-level PL and BET-BJH measurement. The photocatalytic activity of the obtained samples was evaluated by the removal of NO at the indoor air level under simulated solar-light irradiation. Compared with pure (BiO)2CO3, (BiO)2CO3/Ge and (BiO)2CO3/GO nanocomposites exhibited enhanced photocatalytic activity due to their large surface areas and pore volume, and efficient charge separation and transfer. The present work could provide a simple method to construct 2D nanocomposites by efficient utilization of CO2 in green synthetic strategy.

  14. Net soil-atmosphere fluxes mask patterns in gross production and consumption of nitrous oxide and methane in a managed ecosystem

    Science.gov (United States)

    Yang, Wendy H.; Silver, Whendee L.

    2016-03-01

    Nitrous oxide (N2O) and methane (CH4) are potent greenhouse gases that are both produced and consumed in soil. Production and consumption of these gases are driven by different processes, making it difficult to infer their controls when measuring only net fluxes. We used the trace gas pool dilution technique to simultaneously measure gross fluxes of N2O and CH4 throughout the growing season in a cornfield in northern California, USA. Net N2O fluxes ranged 0-4.5 mg N m-2 d-1 with the N2O yield averaging 0.68 ± 0.02. Gross N2O production was best predicted by net nitrogen (N) mineralization, soil moisture, and soil temperature (R2 = 0.60, n = 39, poxidation exhibited a strong positive relationship with gross CH4 production rates (R2 = 0.67, n = 37, p< 0.001), which reached as high as 5.4 mg C m-2 d-1. Our study is the first to demonstrate the simultaneous in situ measurement of gross N2O and CH4 fluxes, and results highlight that net soil-atmosphere fluxes can mask significant gross production and consumption of these trace gases.

  15. Torsion-rotation-vibration effects in the ground and first excited states of methacrolein, a major atmospheric oxidation product of isoprene

    Energy Technology Data Exchange (ETDEWEB)

    Zakharenko, O.; Motiyenko, R. A.; Aviles Moreno, J.-R.; Huet, T. R., E-mail: Therese.Huet@univ-lille1.fr [Laboratoire de Physique des Lasers, Atomes et Molécules, UMR8523 CNRS – Université Lille 1, Bâtiment P5, F- 59655 Villeneuve d’Ascq Cedex (France); Jabri, A. [Laboratoire Inter-universitaire des Systèmes Atmosphériques, CNRS - Universités Paris Est Créteil et Paris Diderot, 61 Avenue du Général de Gaulle, 94010 Créteil Cedex (France); Institute for Physical Chemistry, RWTH Aachen University, Aachen (Germany); Kleiner, I. [Laboratoire Inter-universitaire des Systèmes Atmosphériques, CNRS - Universités Paris Est Créteil et Paris Diderot, 61 Avenue du Général de Gaulle, 94010 Créteil Cedex (France)

    2016-01-14

    Methacrolein is a major oxidation product of isoprene emitted in the troposphere. New spectroscopy information is provided with the aim to allow unambiguous identification of this complex molecule, characterized by a large amplitude motion associated with the methyl top. State-of-the-art millimeter-wave spectroscopy experiments coupled to quantum chemical calculations have been performed. For the most stable s-trans conformer of atmospheric interest, the torsional and rotational structures have been characterized for the ground state, the first excited methyl torsional state (ν{sub 27}), and the first excited skeletal torsional state (ν{sub 26}). The inverse sequence of A and E tunneling sub-states as well as anomalous A-E splittings observed for the rotational lines of v{sub 26} = 1 state clearly indicates a coupling between methyl torsion and skeletal torsion. A comprehensive set of molecular parameters has been obtained. The far infrared spectrum of Durig et al. [Spectrochim. Acta, Part A 42, 89–103 (1986)] was reproduced, and a Fermi interaction between ν{sub 25} and 2ν{sub 27} was evidenced.

  16. Peanut by-products fed to cattle.

    Science.gov (United States)

    Hill, Gary M

    2002-07-01

    Peanut by-products supply substantial quantities of feedstuffs to beef cattle grown in the same region where peanuts are produced. Included in the list of products fed to cattle are peanuts and peanut meal, peanut skins, peanut hulls, peanut hay, and silages. Residual peanut hay is by far the most widely used peanut by-product fed to beef cattle, and if it is properly harvested with minimal leaf shatter, it is comparable to good-quality grass hays in nutrient content. Peanut skins are often included in small quantities in cattle and pet foods, supplying both protein and energy. High tannin content of peanut skins can cause severe performance depressions in beef cattle if peanut skins are included at levels higher than 10% of the diet, unless diets contain relatively high CP (above 15% CP), or additional N sources are added such as ammonia or urea. Because dairy cattle diets are often above 16% CP in the total dietary DM, peanut skins may increase milk production when added at levels up to 16% of the dry matter. Peanut hulls are effectively used as a roughage source at levels up to 20% of beef finishing diets, for bedding in dairy cattle loafing sheds (if tested and found to contain low aflatoxin levels), and in a variety of manufactured products. Peanut hulls are economically priced because of their quantity, their inherent high fiber, and low CP content, and they should not be fed as a primary feedstuffs for beef cattle. Peanut by-products are generally priced below other by-products, and they can be incorporated into a variety of supplements and diets for cow herds, growing-finishing cattle, and dairy cattle. PMID:12235662

  17. Atmospheric Chemistry and Air Pollution

    OpenAIRE

    Gaffney, Jeffrey S.; Marley, Nancy A.

    2003-01-01

    Atmospheric chemistry is an important discipline for understanding air pollution and its impacts. This mini-review gives a brief history of air pollution and presents an overview of some of the basic photochemistry involved in the production of ozone and other oxidants in the atmosphere. Urban air quality issues are reviewed with a specific focus on ozone and other oxidants, primary and secondary aerosols, alternative fuels, and the potential for chlorine releases to amplify oxidant chemistry...

  18. Soil-atmosphere exchange of nitrous oxide, methane and carbon dioxide in a gradient of elevation in the coastal Brazilian Atlantic forest

    Science.gov (United States)

    Sousa Neto, E.; Carmo, J. B.; Keller, M.; Martins, S. C.; Alves, L. F.; Vieira, S. A.; Piccolo, M. C.; Camargo, P.; Couto, H. T. Z.; Joly, C. A.; Martinelli, L. A.

    2011-03-01

    Soils of tropical forests are important to the global budgets of greenhouse gases. The Brazilian Atlantic Forest is the second largest tropical moist forest area of South America, after the vast Amazonian domain. This study aimed to investigate the emissions of nitrous oxide (N2O), carbon dioxide (CO2) and methane (CH4) fluxes along an altitudinal transect and the relation between these fluxes and other climatic, edaphic and biological variables (temperature, fine roots, litterfall, and soil moisture). Annual means of N2O flux were 3.9 (± 0.4), 1.0 (± 0.1), and 0.9 (± 0.2) ng N cm-2 h-1 at altitudes 100, 400, and 1000 m, respectively. On an annual basis, soils consumed CH4 at all altitudes with annual means of -1.0 (± 0.2), -1.8 (± 0.3), and -1.6 (± 0.1) mg m-2 d-1 at 100 m, 400 m and 1000 m, respectively. Estimated mean annual fluxes of CO2 were 3.5, 3.6, and 3.4 μmol m-2 s-1 at altitudes 100, 400 and 1000 m, respectively. N2O fluxes were significantly influenced by soil moisture and temperature. Soil-atmosphere exchange of CH4 responded to changes in soil moisture. Carbon dioxide emissions were strongly influenced by soil temperature. While the temperature gradient observed at our sites is only an imperfect proxy for climatic warming, our results suggest that an increase in air and soil temperatures may result in increases in decomposition rates and gross inorganic nitrogen fluxes that could support consequent increases in soil N2O and CO2 emissions and soil CH4 consumption.

  19. Heterogeneous atmospheric chemistry

    Science.gov (United States)

    Schryer, D. R.

    1982-01-01

    The present conference on heterogeneous atmospheric chemistry considers such topics concerning clusters, particles and microparticles as common problems in nucleation and growth, chemical kinetics, and catalysis, chemical reactions with aerosols, electron beam studies of natural and anthropogenic microparticles, and structural studies employing molecular beam techniques, as well as such gas-solid interaction topics as photoassisted reactions, catalyzed photolysis, and heterogeneous catalysis. Also discussed are sulfur dioxide absorption, oxidation, and oxidation inhibition in falling drops, sulfur dioxide/water equilibria, the evidence for heterogeneous catalysis in the atmosphere, the importance of heterogeneous processes to tropospheric chemistry, soot-catalyzed atmospheric reactions, and the concentrations and mechanisms of formation of sulfate in the atmospheric boundary layer.

  20. Torrefaction of agricultural by-products: Effects of temperature and time on energy yields

    Science.gov (United States)

    Agricultural by-products, such as apple, grape, olive, and tomato pomaces as well as almond and walnut shells, were torrefied at different temperatures and times. Torrefaction of biomass involves heating in an inert atmosphere to remove volatile components for improved grindability and increased ene...

  1. Arsenic Removal from Water Using Industrial By-Products

    Directory of Open Access Journals (Sweden)

    Branislava M. Lekić

    2013-01-01

    Full Text Available In this study, removal of arsenic ions using two industrial by-products as adsorbents is represented. Removal of As(III and As(V from water was carried out with industrial by-products: residual from the groundwater treatment process, iron-manganese oxide coated sand (IMOCS, and blast furnace slag from steel production (BFS, both inexpensive and locally available. In addition, the BFS was modified in order to minimise its deteriorating impact on the initial water quality. Kinetic and equilibrium studies were carried out using batch and fixed-bed column adsorption techniques under the conditions that are likely to occur in real water treatment systems. To evaluate the application for real groundwater treatment, the capacities of the selected materials were further compared to those exhibited by commercial sorbents, which were examined under the same experimental conditions. IMOCS was found to be a good and inexpensive sorbent for arsenic, while BFS and modified slag showed the highest affinity towards arsenic. All examined waste materials exhibited better sorption performances for As(V. The maximum sorption capacity in the batch reactor was obtained for blast furnace slag, 4040 μgAs(V/g.

  2. Effect of oxidizing and reducing atmospheres on Ba(Ti0.90Zr0.10O3:2V ceramics as characterized by piezoresponse force microscopy

    Directory of Open Access Journals (Sweden)

    Francisco Moura

    2011-09-01

    Full Text Available The effect of annealing atmospheres (At amb, N2 and O2 on the electrical properties of Ba(Ti0.90Zr0.10O3:2V (BZT10:2V ceramics obtained by the mixed oxide method was investigated. X-ray photoelectron spectroscopy (XPS analysis indicates that oxygen vacancies present near Zr and Ti ions reduce ferroelectric properties, especially in samples treated in an ambient atmosphere (At amb. BZT10:2V ceramics sintered in a nitrogen atmosphere showed better dielectric behaviour at room temperature with a dielectric permittivity measured at a frequency of 10 kHz equal to 16800 with dielectric loss of 0.023. Piezoelectric force microscopy (PFM images reveal improvement in the piezoelectric coefficient by sintering the sample under nitrogen atmosphere. Thus, BZT10:2V ceramics sintered under a nitrogen atmosphere can be useful for practical applications which include nonvolatile digital memories, spintronics and data-storage media.

  3. Nitrous Oxide Flux

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — Nitrous Oxide (N20) flux is the net rate of nitrous oxide exchange between an ecosystem and the atmosphere. Data of this variable were generated by the USGS...

  4. Formation of C7F15COOH (PFOA) and other perfluorocarboxylic acids during the atmospheric oxidation of 8:2 fluorotelomer alcohol

    DEFF Research Database (Denmark)

    Wallington, T. J.; Hurley, M. D.; Xia, J.;

    2006-01-01

    Calculations using a three-dimensional global atmospheric chemistry model (IMPACT) indicate that n-C8F17CH2CH2-OH (widely used in industrial and consumer products) degrades in the atmosphere to give perfluorooctanoic acid (PFOA) and other perfluorocarboxylic acids (PFCAs). PFOA is persistent, bio...

  5. Soil-atmosphere exchange of nitrous oxide, methane and carbon dioxide in a gradient of elevation in the coastal Brazilian Atlantic forest

    Directory of Open Access Journals (Sweden)

    E. Sousa Neto

    2010-07-01

    Full Text Available Soils of tropical forests are important to the global budgets of greenhouse gases. The Brazilian Atlantic Forest is the second largest tropical moist forest area of South America, after the vast Amazonian domain. This study aimed to investigate the emissions of Nitrous Oxide (N2O and Carbon Dioxide (CO2 as well as methane (CH4 emissions and consumptions along an altitudinal transect and the relation between these fluxes and other climatic, edaphic and biological variables (temperature, fine roots, litterfall, and soil moisture. Annual means of N2O flux were 2.6 (±0.5, 0.9 (±0.1, and 0.7 (±0.2 ng N cm−2 h−1 at altitudes 100, 400, and 1000 m, respectively. On an annual basis, soils consumed CH4 at all altitudes with annual means of −1.0 (±0.2, −1.8 (±0.1, and −1.6 (±0.3 mg m−2 d−1 at 100 m, 400 m and 1000 m, respectively. Although not sampled in the hottest and wettest portion of the year because of instrument malfunctions, mean fluxes of CO2 averaged 3.6 (±0.2, 3.5 (±0.3, and 3.1 (±0.3 μmol m−2 s−1 at altitudes 100, 400 and 1000 m, respectively. N2O fluxes were significantly influenced by soil moisture and temperature. Soil-atmosphere exchange of methane responded to changes in soil moisture. Carbon dioxide emissions were strongly influenced by soil temperature. While the temperature gradient observed at our sites is only an imperfect proxy for climate warming, our results suggest that increasing temperatures will result in increased in microbial activity with a consequent increase in soil N2O and CO2 emissions and soil CH4 consumption.

  6. Microstructure degradation of cermet anodes for solid oxide fuel cells: Quantification of nickel grain growth in dry and in humid atmospheres

    Science.gov (United States)

    Holzer, L.; Iwanschitz, B.; Hocker, Th.; Münch, B.; Prestat, M.; Wiedenmann, D.; Vogt, U.; Holtappels, P.; Sfeir, J.; Mai, A.; Graule, Th.

    The effects of compositional and environmental parameters on the kinetics of microstructural degradation are investigated for porous Ni/CGO anodes in solid oxide fuel cells (SOFC). Improved methodologies of SEM-imaging, segmentation and object recognition are described which enable a precise quantification of nickel grain growth over time. Due to these methodological improvements the grain growth can be described precisely with a standard deviation of only 5-15 nm for each time step. In humid atmosphere (60 vol.% H 2O, 40% N 2/H 2) the growth rates of nickel are very high (up to 140%/100 h) during the initial period (1000 h) the growth rates decrease significantly to nearly 0%/100 h. In contrast, under dry conditions (97 vol.% N 2, 3 vol.% H 2) the growth rates during the initial period are much lower (ca. 1%/100 h) but they do not decrease over a period of 2000 h. In addition to the humidity factor there are other environmental and compositional parameters which have a strong influence on the kinetics of the microstructural degradation. The nickel coarsening is strongly depending on the gas flow rate. Also the initial microstructures and the anode compositions have a big effect on the degradation kinetics. Thereby small average grain sizes, wide distribution of particle size and high contents of nickel lead to higher coarsening and degradation rates. Whereas the nickel coarsening appears to be the dominant degradation mechanism during the initial period (1000 h) in humidified gas. Thereby the evaporation of volatile nickel species may lead to a local increase of the Ni/CGO ratio. Due to the surface wetting of CGO a continuous layer tends to form on the surface of the nickel grains which prevents further grain growth and evaporation of nickel. These phenomena lead to a microstructural reorganization between 1000 and 2300 h of exposure. This complex pattern of degradation phenomena also leads to a change of the amount of active microstructural sites that are

  7. Soil-atmosphere exchange of nitrous oxide, methane and carbon dioxide in a gradient of elevation in the coastal Brazilian Atlantic forest

    Directory of Open Access Journals (Sweden)

    E. Sousa Neto

    2011-03-01

    Full Text Available Soils of tropical forests are important to the global budgets of greenhouse gases. The Brazilian Atlantic Forest is the second largest tropical moist forest area of South America, after the vast Amazonian domain. This study aimed to investigate the emissions of nitrous oxide (N2O, carbon dioxide (CO2 and methane (CH4 fluxes along an altitudinal transect and the relation between these fluxes and other climatic, edaphic and biological variables (temperature, fine roots, litterfall, and soil moisture. Annual means of N2O flux were 3.9 (± 0.4, 1.0 (± 0.1, and 0.9 (± 0.2 ng N cm−2 h−1 at altitudes 100, 400, and 1000 m, respectively. On an annual basis, soils consumed CH4 at all altitudes with annual means of −1.0 (± 0.2, −1.8 (± 0.3, and −1.6 (± 0.1 mg m−2 d−1 at 100 m, 400 m and 1000 m, respectively. Estimated mean annual fluxes of CO2 were 3.5, 3.6, and 3.4 μmol m−2 s−1 at altitudes 100, 400 and 1000 m, respectively. N2O fluxes were significantly influenced by soil moisture and temperature. Soil-atmosphere exchange of CH4 responded to changes in soil moisture. Carbon dioxide emissions were strongly influenced by soil temperature. While the temperature gradient observed at our sites is only an imperfect proxy for climatic warming, our results suggest that an increase in air and soil temperatures may result in increases in decomposition rates and gross inorganic nitrogen fluxes that could support consequent increases in soil N2O and CO2 emissions and soil CH4 consumption.

  8. DISINFECTION BY-PRODUCT FORMATION AND CONTROL BY OZONATION AND BIOTREATMENT

    Science.gov (United States)

    There is increasing interest in using ozone in water treatment because it is a strong disinfectant and is able to oxidize the precursors of some disinfection by-products (DBPs). However, ozonation itself produces DBPs, like aldehydes and ketones, and increases the concentration ...

  9. Oxidation of a chromia-forming nickel base alloy at high temperature in mixed diluted CO/H2O atmospheres

    OpenAIRE

    Rouillard, Fabien; Cabet, Céline; Wolski, Krzysztof; Pijolat, Michèle

    2009-01-01

    Corrosion of a chromia-forming nickel base alloy, Haynes 230_, has been investigated under impure helium containing a few Pa of CO and H2O at 900 °C. It has been found that this alloy reacts simultaneously with CO and H2O. Oxidation by CO has been revealed to occur mainly in the first hours. CO diffuses through the scale via short-circuit pathways and oxidizes Al, Cr and Si at the oxide/metal interface. Kinetics of CO oxidation has been investigated and several rate limiting steps are propose...

  10. T91钢高温水蒸气氧化行为%High temperature oxidation of T91 steel in water vapour atmosphere

    Institute of Scientific and Technical Information of China (English)

    王志武; 谢兴

    2013-01-01

    The oxidation behavior of T91 steel in high temperature water vapor(650℃) is studied experimentally. The oxidation kinetics curves of T91 steel have been mensurated by thermo gravimetric analyzer (TGA) method. The results show that the oxidation kinetics obeys the parabolic law. The oxide scales are examined by X-ray diffraction, scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS). The results show that the formed oxide consists of Fe3 O4 and Fe2 O3; they are flaky, cluster, stripy, granular at different oxidative period. The grain size of oxide is formed with nucleating and growing up. Cr can only be identified from the surface of the oxidation film after lh's oxidation, when the oxidation rate is fast and the subsequent oxidizing reaction is running on the exterior surface of the oxide scale all the time, which is external oxidation. The subsequent oxidizing reaction is running on the exterior surface of the oxide scale all the time, which is external oxidation.%通过T91钢在650℃高温水蒸汽条件下的氧化实验,用静态增重法测定了T91钢的氧化动力学曲线,其氧化动力学遵循类抛物线规律;对氧化膜进行扫描电镜、X射线衍射和能谱分析.结果表明,氧化膜的氧化物类型为Fe2O3和Fe3O4,在不同的氧化时间段分别呈片状、簇状、条状和颗粒状;氧化物晶粒是通过形核和长大形成的;氧化1h时,氧化膜的表面有Cr,其后均未发现Cr,且随后的8h氧化过程中,氧化反应一直在氧化膜的外表层进行,即发生外氧化.

  11. Dynamic Response of CoSb2O6 Trirutile-Type Oxides in a CO2 Atmosphere at Low-Temperatures

    OpenAIRE

    Alex Guillén-Bonilla; Verónica-María Rodríguez-Betancourtt; Martín Flores-Martínez; Oscar Blanco-Alonso; Juan Reyes-Gómez; Lorenzo Gildo-Ortiz; Héctor Guillén-Bonilla

    2014-01-01

    Experimental work on the synthesis of the CoSb2O6 oxide and its CO2 sensing properties is presented here. The oxide was synthesized by a microwave-assisted colloidal method in presence of ethylenediamine after calcination at 600 °C. This CoSb2O6 oxide crystallized in a tetragonal structure with cell parameters  and  Å, and space group P42/mnm. To prove its physical, chemical and sensing properties, the oxide was subjected to a series of te...

  12. Research in physical chemistry and chemical education: Part A: Water Mediated Chemistry of Oxidized Atmospheric Compounds Part B: The Development of Surveying Tools to Determine How Effective Laboratory Experiments Contribute to Student Conceptual Understanding

    Science.gov (United States)

    Maron, Marta Katarzyna

    This dissertation is a combination of two research areas, experimental physical chemistry, Chapters I to V, and chemical education, Chapters VI to VII. Chapters I to V describe research on the water-mediated chemistry of oxidized atmospheric molecules and the impact that water has on the spectra of these environmental systems. The role of water in the Earth's atmosphere has been of considerable interest due to its ability to impact chemistry and climate. Oxidized atmospheric molecules in the presence of water have the ability to form hydrogen bonded water complexes. The spectroscopic investigation of nitric acid-water complexes, outlined in Chapter III, was undertaken to characterize intermolecular hydrogen bonds in a water-restricted environment at ambient temperatures. Additionally, this characterization of nitric acid-water complexes allowed for the comparison of calculated overtone OH-stretching vibrational band frequencies, intensities, and anharmonicities of intermolecular hydrogen-bonded water complexes with experimental observations. Oxidized organic molecules, such as aldehydes and ketones, in addition to forming hydrogen-bonded water complexes can undergo a hydration reaction of the carbonyl group and form germinal diols in the presence of water. This chemistry has been studied extensively in bulk aqueous media, however little is known about this process in the gas-phase at low water concentrations. The focus of the studies outlined in Chapters IV and V is motivated by the ability of pyruvic acid and formaldehyde to form germinal diols and water complexes in water-restricted environment. This water-mediated chemistry changes the physical and chemical properties of these organic molecules, therefore, impacting the partitioning between gas and particle phase, as well as the chemistry and photochemistry of oxidized organic molecules in the Earth's atmosphere. The results presented in this dissertation may help resolve the significant discrepancy between

  13. Staging atmospheres

    DEFF Research Database (Denmark)

    Bille, Mikkel; Bjerregaard, Peter; Sørensen, Tim Flohr

    2015-01-01

    The article introduces the special issue on staging atmospheres by surveying the philosophical, political and anthropological literature on atmosphere, and explores the relationship between atmosphere, material culture, subjectivity and affect. Atmosphere seems to occupy one of the classic...... localities of tensions between matter and the immaterial, the practical and the ideal, and subject and object. In the colloquial language there can, moreover, often seem to be something authentic or genuine about atmosphere, juxtaposing it to staging, which is implied to be something simulated or artificial....... This introduction seeks to outline how a number of scholars have addressed the relationship between staged atmospheres and experience, and thus highlight both the philosophical, social and political aspects of atmospheres...

  14. Atmospheric chemistry of 4 : 2 fluorotelomer alcohol (CF3(CF2)(3)CH2CH2OH): Products and mechanism of Cl atom initiated oxidation

    DEFF Research Database (Denmark)

    Hurley, MD; Ball, JC; Wallington, TJ;

    2004-01-01

    Smog chamber/FTIR techniques were used to study the products and mechanism of the Cl atom initiated oxidation of 4:2 fluorotelomer alcohol (CF3(CF2)(3)CH2CH2OH) in 700 Torr of N-2/O-2 diluent at 296 K. CF3(CF2)(3)CH2CHO is the sole primary oxidation product. CF3(CF2)(3)CHO, CF3(CF2)(3)CH2COOH, an...

  15. An identical-location transmission electron microscopy study on the degradation of Pt/C nanoparticles under oxidizing, reducing and neutral atmosphere

    International Nuclear Information System (INIS)

    This study shows that the predominant degradation mechanism of Pt/Vulcan XC72 electrocatalysts strongly depends on the nature of the gas atmosphere and of the upper potential limit used in accelerated stress tests (ASTs). The morphological changes of Pt/Vulcan XC72 nanoparticles were studied by identical location transmission electron microscopy (IL-TEM), following accelerated stress tests in different potential ranges and under various gas atmospheres. X-ray photoelectron spectroscopy was used to probe changes in carbon surface chemistry. Whereas minor changes were detected under neutral atmosphere (Ar) and low potential limit conditions (0.05 2). With an increase of the upper potential limit to 1.23 V vs. RHE, the trends observed previously were maintained but 3D Ostwald ripening strongly overlapped with the three other degradation mechanisms, precluding any identification of the dominant mechanism

  16. Effect of capacitive deionization on disinfection by-product precursors.

    Science.gov (United States)

    Liu, Danyang; Wang, Xiaomao; Xie, Yuefeng F; Tang, Hao L

    2016-10-15

    Formation of brominated disinfection by-products (DBPs) from bromide and natural organic matter upon chlorination imposes health risks to drinking water users. In this study, capacitive deionization (CDI) was evaluated as a potential process for DBP precursor removal. Synthetic humic acid and bromide containing saline water was used as model water prior to CDI treatment. Batch experiments were conducted at cell voltages of 0.6-, 0.9-, and 1.2V to study the influence of CDI on the ratio of bromide and dissolved organic carbon, bromine substitution factor, and DBP formation potential (FP). Results showed beneficial aspects of CDI on reducing the levels of these parameters. A maximum DBPFP removal from 1510 to 1160μg/L was observed at the cell voltage of 0.6V. For the removed DBPFP, electro-adsorption played a greater role than physical adsorption. However, it is also noted that there could be electrochemical oxidations that led to reduction of humic content and formation of new dichloroacetic acid precursors at high cell voltages. Because of the potential of CDI on reducing health risks from the formation of less brominated DBPs upon subsequent chlorination, it can be considered as a potential technology for DBP control in drinking water treatment. PMID:27285792

  17. Disinfection by-product formation during seawater desalination: A review.

    Science.gov (United States)

    Kim, Daekyun; Amy, Gary L; Karanfil, Tanju

    2015-09-15

    Due to increased freshwater demand across the globe, seawater desalination has become the technology of choice in augmenting water supplies in many parts of the world. The use of chemical disinfection is necessary in desalination plants for pre-treatment to control both biofouling as well as the post-disinfection of desalinated water. Although chlorine is the most commonly used disinfectant in desalination plants, its reaction with organic matter produces various disinfection by-products (DBPs) (e.g., trihalomethanes [THMs], haloacetic acids [HAAs], and haloacetonitriles [HANs]), and some DBPs are regulated in many countries due to their potential risks to public health. To reduce the formation of chlorinated DBPs, alternative oxidants (disinfectants) such as chloramines, chlorine dioxide, and ozone can be considered, but they also produce other types of DBPs. In addition, due to high levels of bromide and iodide concentrations in seawater, highly cytotoxic and genotoxic DBP species (i.e., brominated and iodinated DBPs) may form in distribution systems, especially when desalinated water is blended with other source waters having higher levels of organic matter. This article reviews the knowledge accumulated in the last few decades on DBP formation during seawater desalination, and summarizes in detail, the occurrence of DBPs in various thermal and membrane plants involving different desalination processes. The review also identifies the current challenges and future research needs for controlling DBP formation in seawater desalination plants and to reduce the potential toxicity of desalinated water. PMID:26099832

  18. Energy, atmospheric chemistry, and global climate

    Science.gov (United States)

    Levine, Joel S.

    1991-01-01

    Global atmospheric changes due to ozone destruction and the greenhouse effect are discussed. The work of the Intergovernmental Panel on Climate Change is reviewed, including its judgements regarding global warming and its recommendations for improving predictive capability. The chemistry of ozone destruction and the global atmospheric budget of nitrous oxide are reviewed, and the global sources of nitrous oxide are described.

  19. Aqueous chlorination of mefenamic acid: kinetics, transformation by-products and ecotoxicity assessment.

    Science.gov (United States)

    Adira Wan Khalit, Wan Nor; Tay, Kheng Soo

    2016-05-18

    Mefenamic acid (Mfe) is one of the most frequently detected nonsteroidal anti-inflammatory drugs in the environment. This study investigated the kinetics and the transformation by-products of Mfe during aqueous chlorination. The potential ecotoxicity of the transformation by-products was also evaluated. In the kinetic study, the second-order rate constant (kapp) for the reaction between Mfe and free available chlorine (FAC) was determined at 25 ± 0.1 °C. The result indicated that the degradation of Mfe by FAC is highly pH-dependent. When the pH was increased from 6 to 8, it was found that the kapp for the reaction between Mfe and FAC was decreased from 16.44 to 4.4 M(-1) s(-1). Characterization of the transformation by-products formed during the chlorination of Mfe was carried out using liquid chromatography-quadrupole time-of-flight accurate mass spectrometry. Four major transformation by-products were identified. These transformation by-products were mainly formed through hydroxylation, chlorination and oxidation reactions. Ecotoxicity assessment revealed that transformation by-products, particularly monohydroxylated Mfe which is more toxic than Mfe, can be formed during aqueous chlorination.

  20. Efficiencies of metal separation and recovery in ash-melting of municipal solid waste under non-oxidative atmospheres with different reducing abilities.

    Science.gov (United States)

    Okada, Takashi; Tomikawa, Hiroki

    2016-01-15

    Ash-melting of municipal solid waste produces molten metal that contains Fe and Cu, and melting furnace fly ash (MFA) that contains Pb and Zn. To recover the metal from the fly ash, Pb and Zn are extracted from the ash by water or enriched in the ash by washing out salts; this separation depends on their leachability. In this study, we investigated the effects of the reducing ability of the atmosphere on the efficiencies of metal separation during melting and metal recovery in water treatment. Different feedstocks (incineration residues) were melted under N2 or CO + N2 atmospheres. In some of the feedstock materials, volatilization of metallic Cu into MFA was promoted under the atmosphere with greater reducing ability (CO + N2). This increased volatilization inhibited the metal separation in the ash-melting process. Moreover, the higher reducing ability inhibited the formation of water-soluble lead chlorides and decreased the efficiency of metal recovery from the MFA because of the water leaching of the lead compounds. The reducing ability of the atmosphere is difficult to control uniformly in actual ash-melting plants, and we investigated appropriate melting conditions under which the effect of the reducing ability was minimized to promote metal separation and recovery. This minimization was achieved by melting incineration fly ash without additives with Cl gas treatment at 1400 °C.

  1. Exoplanet Atmospheres

    CERN Document Server

    Seager, S

    2010-01-01

    At the dawn of the first discovery of exoplanets orbiting sun-like stars in the mid-1990s, few believed that observations of exoplanet atmospheres would ever be possible. After the 2002 Hubble Space Telescope detection of a transiting exoplanet atmosphere, many skeptics discounted it as a one-object, one-method success. Nevertheless, the field is now firmly established, with over two dozen exoplanet atmospheres observed today. Hot Jupiters are the type of exoplanet currently most amenable to study. Highlights include: detection of molecular spectral features; observation of day-night temperature gradients; and constraints on vertical atmospheric structure. Atmospheres of giant planets far from their host stars are also being studied with direct imaging. The ultimate exoplanet goal is to answer the enigmatic and ancient question, "Are we alone?" via detection of atmospheric biosignatures. Two exciting prospects are the immediate focus on transiting super Earths orbiting in the habitable zone of M-dwarfs, and u...

  2. Atmospheric Neutrinos

    OpenAIRE

    Takaaki Kajita

    2012-01-01

    Atmospheric neutrinos are produced as decay products in hadronic showers resulting from collisions of cosmic rays with nuclei in the atmosphere. Electron-neutrinos and muon-neutrinos are produced mainly by the decay chain of charged pions to muons to electrons. Atmospheric neutrino experiments observed zenith angle and energy-dependent deficit of muon-neutrino events. It was found that neutrino oscillations between muon-neutrinos and tau-neutrinos explain these data well. This paper discusses...

  3. Articulating Atmospheres

    DEFF Research Database (Denmark)

    Kinch, Sofie

    2011-01-01

    This paper presents an architectural approach to designing computational interfaces by articulating the notion of atmosphere in the field of interaction design. It draws upon the concept of kinesthetic interaction and a philosophical notion on atmosphere emphasizing the importance of bodily...... experience in space, presented as middle ground experience. In the field of HCI, middle ground experiences complete the unarticulated spectrum between designing for foreground of attention or background awareness. When “Articulating Atmospheres through Middle Ground Experiences in Interaction Design...

  4. How and why electrostatic charge of combustible nanoparticles can radically change the mechanism and rate of their oxidation in humid atmosphere

    CERN Document Server

    Meshcheryakov, Oleg

    2010-01-01

    Electrostatically charged aerosol nanoparticles strongly attract surrounding polar gas molecules due to a charge-dipole interaction. In humid air, the substantial electrostatic attraction and acceleration of surrounding water vapour molecules towards charged combustible nanoparticles cause intense electrostatic hydration and preferential oxidation of these nanoparticles by accelerated water vapor molecules rather than non-polar oxygen molecules. In particular, electrostatic acceleration, acquired by surrounding water vapour molecules at a distance of their mean free path from the minimally charged iron metal nanoparticle can increase an oxidative activity of these polar molecules with respect to the nanoparticle by a factor of one million. Intense electrostatic hydration of charged metal nanoparticles converts the nanoparticle's oxide based shells into the hydroxide based electrolyte shells, transforming these nanoparticles into metal/air core-shell nanobatteries, periodically short-circuited by intra-particl...

  5. Pluto's atmosphere

    International Nuclear Information System (INIS)

    Airborne CCD photometer observations of Pluto's June 9, 1988 stellar occultation have yielded an occultation lightcurve, probing two regions on the sunrise limb 2000 km apart, which reveals an upper atmosphere overlying an extinction layer with an abrupt upper boundary. The extinction layer may surround the entire planet. Attention is given to a model atmosphere whose occultation lightcurve closely duplicates observations; fits of the model to the immersion and emersion lightcurves exhibit no significant derived atmosphere-structure differences. Assuming a pure methane atmosphere, surface pressures of the order of 3 microbars are consistent with the occultation data. 43 references

  6. Atmospheric electricity

    CERN Document Server

    Chalmers, J Alan

    1957-01-01

    Atmospheric Electricity brings together numerous studies on various aspects of atmospheric electricity. This book is composed of 13 chapters that cover the main problems in the field, including the maintenance of the negative charge on the earth and the origin of the charges in thunderstorms. After a brief overview of the historical developments of atmospheric electricity, this book goes on dealing with the general principles, results, methods, and the MKS system of the field. The succeeding chapters are devoted to some aspects of electricity in the atmosphere, such as the occurrence and d

  7. High-temperature oxidation of iron, Fe-0.5 wt. % Al and Fe-1 wt% Al alloys in CO2 at atmospheric pressure

    International Nuclear Information System (INIS)

    The oxidation of several grades of iron (on being a zone-melting grade) in the poly- and monocrystalline forms between 570 and 11500C proceeds along a linear, then a transitory and a parabolic law in correspondence with the growth of wustite possibly covered with magnetite, whereas in the 400-5700C range where the parabolic law is rapidly establishing, the scale is entirely formed of magnetite. The oxidation of the two Fe-A1 alloys follows similarly a quasi linear law after a very short linear period. Their weight gains differ only at 10% at most while remaining close to that of iron (except above 5700C where they are much lower). The activation energies correspponding to the parabolic process -and in some cases to the linear one- have been determined for each material. They are in the range 11 to 43 Kcal.mole-1, such values being rather low. The characteristics of the oxide layers: mode and facies of nucleation and crystal growth -particularly of the ridges at grain boundaries- the evolution of interfaces, precipitation of magnetite within wustite, etc... have been thoroughly investigated. Finally mechanisms concerning the linear, transitory and parabolic oxidation processes have been proposed after a careful discussion of the results

  8. Dynamic Response of CoSb2O6 Trirutile-Type Oxides in a CO2 Atmosphere at Low-Temperatures

    Directory of Open Access Journals (Sweden)

    Alex Guillén-Bonilla

    2014-08-01

    Full Text Available Experimental work on the synthesis of the CoSb2O6 oxide and its CO2 sensing properties is presented here. The oxide was synthesized by a microwave-assisted colloidal method in presence of ethylenediamine after calcination at 600 °C. This CoSb2O6 oxide crystallized in a tetragonal structure with cell parameters  and  Å, and space group P42/mnm. To prove its physical, chemical and sensing properties, the oxide was subjected to a series of tests: Raman spectroscopy, Scanning Electron Microscopy (SEM and impedance (Z measurements. Microstructures, like columns, bars and hollow hemispheres, were observed. For the CO2 sensing test, a thick film of CoSb2O6 was used, measuring the impedance variations on the presence of air/CO2 flows (0.100 sccm/0.100 sccm using AC (alternating current signals in the frequency-range 0.1–100 kHz and low relative temperatures (250 and 300 °C. The CO2 sensing results were quite good.

  9. Fluctuations in late Neoproterozoic atmospheric oxidation — Cr isotope chemostratigraphy and iron speciation of the late Ediacaran lower Arroyo del Soldado Group (Uruguay)

    DEFF Research Database (Denmark)

    Frei, Robert; Gaucher, Claudio; Stolper, Daniel;

    2013-01-01

    .0‰) in iron-rich cherts and banded iron formation horizons within the Arroyo del Soldado Group (Ediacaran; Uruguay) that can be explained by rapid, effective oxidation of Fe(II)-rich surface waters. These fluctuations are correlated with variations in ratios of highly reactive iron (FeHR) to total iron (Fetot...

  10. Kinetic study of the OH, NO3 radicals and Cl atom initiated atmospheric photo-oxidation of iso-propenyl methyl ether

    Science.gov (United States)

    Taccone, Raúl Alberto; Moreno, Alberto; Colmenar, Inmaculada; Salgado, Sagrario; Martín, María Pilar; Cabañas, Beatriz

    2016-02-01

    Rate coefficients at room temperature and atmospheric pressure for the reaction of isopropenyl methyl ether (i-PME) (CH2dbnd C(CH3)OCH3), with OH and NO3 radicals and with Cl atoms have been determined in a 50 L Pyrex glass reaction chamber in conjunction with Fourier Transform Infrared absorption spectroscopy (FTIR) as a detection technique. The chamber is equipped with a White-type multiple-reflection mirror system with a total optical path length of ≈200 m. Additional experiments were carried out using evacuable Teflon-coated bags (volume 150 L) and a gas chromatography/mass spectrometry-time of flight (GC-TOF MS) detection system. This is the first kinetic study carried out to date for these reactions. The rate coefficients k (in units of cm3 molecule-1 s-1) obtained are: (1.14 ± 0.10) × 10-10 for the OH reaction, (2.41 ± 0.50) × 10-11, for the NO3 reaction and (7.03 ± 0.67) × 10-10 for the Cl reaction. A mechanism is proposed from the observed reaction products. The atmospheric lifetimes of the studied ether is estimated considering the rate coefficients of the reactions with OH and NO3 radicals and Cl atom. Calculated atmospheric lifetimes reveal that the dominant loss process for i-PME is clearly the night-time reaction with the NO3 radical. The radiative efficiency (RE) is obtained from the infrared spectra of the ether and the global warming potential (GWP) is then estimated. Atmospheric implications of the ether emission are discussed.

  11. Atmospheric CO2, d(O2/N2), APO and oxidative ratios from aircraft flask samples over Fyodorovskoye, Western Russia

    NARCIS (Netherlands)

    Laan, van der S.; Laan-Luijkx, van der I.T.; Rödenbeck, C.; Varlagin, A.; Shironya, I.; Neubert, R.E.M.

    2014-01-01

    We present atmospheric CO2 and d(O2/N2) from flask samples taken on board aircraft over Fyodorovskoye (56°27'N, 32°55'E) at heights of 3000 m and 100 m between 1998 and 2008. The long-term trends for CO2 and d(O2/N2) are similar for both sampling heights, and also similar to observations from marine

  12. Atmospheric CO2, delta(O-2/N-2), APO and oxidative ratios from aircraft flask samples over Fyodorovskoye, Western Russia

    NARCIS (Netherlands)

    van der Laan, Sander; van der Laan - Luijkx, Ingrid; Roedenbeck, C.; Varlagin, A.; Shironya, I.; Neubert, R. E. M.; Ramonet, M.; Meijer, H. A. J.

    2014-01-01

    We present atmospheric CO2 and delta(O-2/N-2) from flask samples taken on board aircraft over Fyodorovskoye (56 degrees 27'N, 32 degrees 55'E) at heights of 3000 m and 100 m between 1998 and 2008. The long-term trends for CO2 and delta(O-2/N-2) are similar for both sampling heights, and also similar

  13. Atmospheric Chemistry of cis-CF3CH=CHF: Kinetics of reactions with OH radicals and O3 and products of OH radical initiated oxidation

    DEFF Research Database (Denmark)

    Nilsson, Elna Johanna Kristina; Nielsen, Ole John; Johnson, Matthew Stanley;

    2009-01-01

    which are indistinguishable from 100%. The atmospheric lifetime of cis-CF3CH@CHF is determined by its reaction with OH and is approximately 10 days. cis-CF3CH@CHF has an integrated IR absorption cross section (600–2000 cm1) of (1.71 ± 0.09) 1016 cm molecule1 and a global warming potential...... of approximately 3 (100 year time horizon). Quoted uncertainties reflect two standard deviations from least squares regression analyses....

  14. Maximizing Utilization of Energy from Crop By-products

    OpenAIRE

    Budi Haryanto

    2014-01-01

    The availability of crop by-products is huge during harvesting times as related to the vast agricultural land area; however, their utilization is still limited due to lack of knowledge and handling problem. Seasonal effect is obvious especially during wet season when high rainfall hinders proper management of crop by-products. Crop by-products are energy rich feedstuffs in the form of chemical substance such as cellulose and hemicellulose. The utilization of cellulose and hemicellulose as sou...

  15. Chemical stabilization of cadmium in acidic soil using alkaline agronomic and industrial by-products.

    Science.gov (United States)

    Chang, Yao-Tsung; Hsi, Hsing-Cheng; Hseu, Zeng-Yei; Jheng, Shao-Liang

    2013-01-01

    In situ immobilization of heavy metals using reactive or stabilizing materials is a promising solution for soil remediation. Therefore, four agronomic and industrial by-products [wood biochar (WB), crushed oyster shell (OS), blast furnace slag (BFS), and fluidized-bed crystallized calcium (FBCC)] and CaCO3 were added to acidic soil (Cd = 8.71 mg kg(-1)) at the rates of 1%, 2%, and 4% and incubated for 90 d. Chinese cabbage (Brassica chinensis L.) was then planted in the soil to test the Cd uptake. The elevation in soil pH caused by adding the by-products produced a negative charge on the soil surface, which enhanced Cd adsorption. Consequently, the diethylenetriamine pentaacetic acid (DTPA)-extractable Cd content decreased significantly (P < 0.05) in the incubated soil. These results from the sequential extraction procedure indicated that Cd converted from the exchangeable fraction to the carbonate or Fe-Mn oxide fraction. The long-term effectiveness of Cd immobilization caused by applying the 4 by-products was much greater than that caused by applying CaCO3. Plant shoot biomass clearly increased because of the by-product soil amendment. Cd concentration in the shoots was < 10.0 mg kg(-1) following by-product application, as compared to 24 mg kg(-1) for plants growing in unamended soil. PMID:23947715

  16. Sterilization of E.coli bacterium with an atmospheric pressure surface barrier discharge

    Institute of Scientific and Technical Information of China (English)

    Xu Lei; Zhang Rui; Liu Peng; Ding Li-Li; Zhan Ru-Juan

    2004-01-01

    The atmospheric pressure surface barrier discharge (APSBD) in air has been used in killing Escherichia coli (E.coli). There is almost no bacterial colony in the sample after treatment by discharge plasma for 2 min. A diagnostic technique based on mass spectrum has been applied to the discharge gas and the mechanism of killing is discussed.Ozone and monatomic oxide are considered to be the major antimicrobial active species. There is almost no harmful by-product. The experiment proves that APSBD plasma is a very simple, effective and innocuous tool for sterilization.

  17. Conductivity of perovskites La0.9Sr0.1Sc1- x Fe x O3-α ( x = 0.003-0.47) in oxidizing and reducing atmospheres

    Science.gov (United States)

    Stroeva, A. Yu.; Gorelov, V. P.; Kuz'min, A. V.

    2016-08-01

    The conductivity of single-phase ceramic materials based on proton-conducting perovskite La0.9Sr0.1ScO3-α containing from 0.3 to 47 at % Fe in the scandium sublattice has been studied. Synthesis has been performed by burning with ethylene glycol. Measurements have been carried out by the four-probe (500-900°C) and impedance (100-500°C) methods in oxidizing and reducing atmospheres, as well as at different pressures {p_{{O_2}}} (2.1 × 104-10‒15 Pa) and {p_{{H_2}O}} (0.04-2.5 kPa). Substitution of scandium with iron significantly decreases the proton conductivity.

  18. Exoplanetary Atmospheres

    CERN Document Server

    Madhusudhan, Nikku; Fortney, Jonathan; Barman, Travis

    2014-01-01

    The study of exoplanetary atmospheres is one of the most exciting and dynamic frontiers in astronomy. Over the past two decades ongoing surveys have revealed an astonishing diversity in the planetary masses, radii, temperatures, orbital parameters, and host stellar properties of exoplanetary systems. We are now moving into an era where we can begin to address fundamental questions concerning the diversity of exoplanetary compositions, atmospheric and interior processes, and formation histories, just as have been pursued for solar system planets over the past century. Exoplanetary atmospheres provide a direct means to address these questions via their observable spectral signatures. In the last decade, and particularly in the last five years, tremendous progress has been made in detecting atmospheric signatures of exoplanets through photometric and spectroscopic methods using a variety of space-borne and/or ground-based observational facilities. These observations are beginning to provide important constraints...

  19. Atmospheric composition

    Science.gov (United States)

    Daniels, G. E.

    1973-01-01

    The earth's atmosphere is made up of a number of gases in different relative amounts. Near sea level and up to about 90 km, the amount of these atmospheric gases in clean, relatively dry air is practically constant. Four of these gases, nitrogen, oxygen, argon, and carbon dioxide, make up 99.99 percent by volume of the atmosphere. Two gases, ozone and water vapor, change in relative amounts, but the total amount of these two is very small compared to the amount of the other gases. The atmospheric composition shown in a table can be considered valid up to 90 km geometric altitude. Above 90 km, mainly because of molecular dissociation and diffusive separation, the composition changes.

  20. Interpreting the Ultraviolet Aerosol Index Observed with the OMI Satellite Instrument to Understand Absorption by Organic Carbon Aerosols and Implications for Atmospheric Oxidation

    Science.gov (United States)

    Hammer, M. S.; Martin, R.; van Donkelaar, A.; Buchard, V.; Torres, O.; Ridley, D. A.; Spurr, R. J. D.

    2015-12-01

    Absorption of solar radiation by aerosols plays a major role in radiative forcing and atmospheric photochemistry. Many atmospheric chemistry models tend to overestimate tropospheric OH concentrations compared to observations. Accurately representing aerosol absorption in the UV could help rectify the discrepancies between simulated and observed OH concentrations. We develop a simulation of the Ultraviolet Aerosol Index (UVAI), using the 3-D chemical transport model GEOS-Chem coupled with the Vector Linearized Discrete Ordinate Radiative Transfer model (VLIDORT). The simulation is applied to interpret UVAI observations from the Ozone Monitoring Instrument (OMI). Simulated and observed values are highly consistent in regions where mineral dust dominates the UVAI, but a large negative bias (-0.4 to -1.0) exists between simulated and observed values in biomass burning regions. We implement optical properties for absorbing organic aerosol, known as brown carbon (BrC), into GEOS-Chem and evaluate the simulation with observed UVAI values over biomass burning regions. The spectral dependence of absorption after adding BrC to the model is broadly consistent with reported observations for biomass burning aerosol, with Absorbing Angstrom Exponent (AAE) values ranging from 2.7 in the UV to 1.3 across the UV-Near IR spectrum. The addition of absorbing BrC decreases the mean bias between simulated and OMI UVAI values from -0.60 to -0.08 over North Africa in January, from -0.40 to -0.003 over South Asia in April, from -1.0 to -0.24 over southern Africa in July, and from -0.50 to +0.34 over South America in September. We assess the effect of the additional UV absorption by BrC on atmospheric photochemistry by examining ozone photolysis frequencies (J(O(1D))) and tropospheric OH concentrations in GEOS-Chem. The inclusion of BrC decreases J(O(1D)) and OH by up to 35% over biomass burning regions, and reduces the global bias in OH.

  1. Nióbia sintética modificada como catalisador na oxidação de corante orgânico: utilização de H2O2 e O2 atmosférico como oxidantes Modified synthetic niobia as catalyst in the oxidation of organic dye: utilization of H2O2 and atmospheric O2 as oxidants

    Directory of Open Access Journals (Sweden)

    Kele T. G. Carvalho

    2009-01-01

    Full Text Available In this work synthetic niobia was used to promote the oxidation of methylene blue dye in aqueous medium. The niobia was characterized by N2 adsorption/desorption, XRD and TG measurements. The presence of reactive species on the niobia surface strongly increased the oxidation rate of the methylene blue dye. The reaction mechanism was studied by ESI-MS suggesting that the oxidation of the organic dye involve oxidizing species generated mainly after previous treatment with H2O2. It can be observed that the catalyst is a good material in the activation of gas (atmospheric oxygen or liquid (hydrogen peroxide oxidant agent with a total discoloration of the dye solution after only 1 h of reaction.

  2. Nitrous oxide in fresh water systems: An estimate for the yield of atmospheric N2O associated with disposal of human waste

    Science.gov (United States)

    Kaplan, W. A.; Elkins, J. W.; Kolb, C. E.; Mcelroy, M. B.; Wofsy, S. C.; Duran, A. P.

    1977-01-01

    The N2O content of waters in the Potomac and Merrimack Rivers was measured on a number of occasions over the period April to July 1977. The concentrations of dissolved N2O exceeded those which would apply in equilibrium with air by factors ranging from about 46 in the Potomac to 1.2 in the Merrimack. Highest concentrations of dissolved N2O were associated with sewage discharges from the vicinity of Washington, D. C., and analysis indicates a relatively high yield, 1.3 to 11%, for prompt conversion of waste nitrogen to N2O. Measurements of dissolved N2O in fresh water ponds near Boston demonstrated that aquatic systems provide both strong sources and sinks for atmospheric N2O.

  3. Atmospheric oxidation of 1,3-butadiene: characterization of gas and aerosol reaction products and implications for PM2.5

    Science.gov (United States)

    Jaoui, M.; Lewandowski, M.; Docherty, K.; Offenberg, J. H.; Kleindienst, T. E.

    2014-12-01

    examined. The contribution of SOA products from 13BD oxidation to ambient PM2.5 was investigated by analyzing a series of ambient PM2.5 samples collected in several locations around the United States. In addition to the occurrence of several organic compounds in field and laboratory samples, glyceric acid, d-threitol, erythritol, erythrose, and threonic acid were found to originate only from the oxidation of 13BD based on our previous experiments involving chamber oxidation of a series of hydrocarbons. Initial attempts have been made to quantify the concentrations of these compounds. The average concentrations of these compounds in ambient PM2.5 samples from the California Research at the Nexus of Air Quality and Climate Change (CalNex) study ranged from 0 to approximately 14.1 ng m-3. The occurrence of several other compounds in both laboratory and field samples suggests that SOA originating from 13BD oxidation could contribute to the ambient aerosol mainly in areas with high 13BD emission rates.

  4. By-products of palm oil extraction and refining

    OpenAIRE

    Tan Yew-Ai

    2006-01-01

    This paper outlines the utilisation of by-products resulting from the extraction and refining of palm oil. It summarises research by the Malaysian Palm Oil Board (MPOB) directed at producing zero waste from the palm oil industry. MPOB regards by-products of the palm oil industry not as waste but resources. It will be evident that by-products from the palm oil industry can be and have been used extensively and that the research carried out is relevant to both the milling and refining sectors.

  5. By-products of palm oil extraction and refining

    Directory of Open Access Journals (Sweden)

    Tan Yew-Ai

    2006-01-01

    Full Text Available This paper outlines the utilisation of by-products resulting from the extraction and refining of palm oil. It summarises research by the Malaysian Palm Oil Board (MPOB directed at producing zero waste from the palm oil industry. MPOB regards by-products of the palm oil industry not as waste but resources. It will be evident that by-products from the palm oil industry can be and have been used extensively and that the research carried out is relevant to both the milling and refining sectors.

  6. Bioactive peptides generated from meat industry by-products

    OpenAIRE

    Mora, Leticia; Reig, Milagro; Toldrá, Fidel

    2014-01-01

    There is a large generation of meat by-products, not only from slaughtering but also in the meat industry from trimming and deboning during further processing. This results in extraordinary volumes of by-products that are primarily used as feeds with low returns or, more recently, to biodiesel generation. The aim of this work was to review the state of the art to generate bioactive peptides from meat industry by-products giving them an added value. Hydrolysis with commercial proteases constit...

  7. A Review of Antioxidant Peptides Derived from Meat Muscle and By-Products

    Science.gov (United States)

    Liu, Rui; Xing, Lujuan; Fu, Qingquan; Zhou, Guang-hong; Zhang, Wan-gang

    2016-01-01

    Antioxidant peptides are gradually being accepted as food ingredients, supplemented in functional food and nutraceuticals, to positively regulate oxidative stress in the human body against lipid and protein oxidation. Meat muscle and meat by-products are rich sources of proteins and can be regarded as good materials for the production of bioactive peptides by use of enzymatic hydrolysis or direct solvent extraction. In recent years, there has been a growing number of studies conducted to characterize antioxidant peptides or hydrolysates derived from meat muscle and by-products as well as processed meat products, including dry-cured hams. Antioxidant peptides obtained from animal sources could exert not only nutritional value but also bioavailability to benefit human health. This paper reviews the antioxidant peptides or protein hydrolysates identified in muscle protein and by-products. We focus on the procedure for the generation of peptides with antioxidant capacity including the acquisition of crude peptides, the assessment of antioxidant activity, and the purification and identification of the active fraction. It remains critical to perform validation experiments with a cell model, animal model or clinical trial to eliminate safety concerns before final application in the food system. In addition, some of the common characteristics on structure-activity relationship are also reviewed based on the identified antioxidant peptides. PMID:27657142

  8. A Review of Antioxidant Peptides Derived from Meat Muscle and By-Products

    Directory of Open Access Journals (Sweden)

    Rui Liu

    2016-09-01

    Full Text Available Antioxidant peptides are gradually being accepted as food ingredients, supplemented in functional food and nutraceuticals, to positively regulate oxidative stress in the human body against lipid and protein oxidation. Meat muscle and meat by-products are rich sources of proteins and can be regarded as good materials for the production of bioactive peptides by use of enzymatic hydrolysis or direct solvent extraction. In recent years, there has been a growing number of studies conducted to characterize antioxidant peptides or hydrolysates derived from meat muscle and by-products as well as processed meat products, including dry-cured hams. Antioxidant peptides obtained from animal sources could exert not only nutritional value but also bioavailability to benefit human health. This paper reviews the antioxidant peptides or protein hydrolysates identified in muscle protein and by-products. We focus on the procedure for the generation of peptides with antioxidant capacity including the acquisition of crude peptides, the assessment of antioxidant activity, and the purification and identification of the active fraction. It remains critical to perform validation experiments with a cell model, animal model or clinical trial to eliminate safety concerns before final application in the food system. In addition, some of the common characteristics on structure-activity relationship are also reviewed based on the identified antioxidant peptides.

  9. A Review of Antioxidant Peptides Derived from Meat Muscle and By-Products.

    Science.gov (United States)

    Liu, Rui; Xing, Lujuan; Fu, Qingquan; Zhou, Guang-Hong; Zhang, Wan-Gang

    2016-01-01

    Antioxidant peptides are gradually being accepted as food ingredients, supplemented in functional food and nutraceuticals, to positively regulate oxidative stress in the human body against lipid and protein oxidation. Meat muscle and meat by-products are rich sources of proteins and can be regarded as good materials for the production of bioactive peptides by use of enzymatic hydrolysis or direct solvent extraction. In recent years, there has been a growing number of studies conducted to characterize antioxidant peptides or hydrolysates derived from meat muscle and by-products as well as processed meat products, including dry-cured hams. Antioxidant peptides obtained from animal sources could exert not only nutritional value but also bioavailability to benefit human health. This paper reviews the antioxidant peptides or protein hydrolysates identified in muscle protein and by-products. We focus on the procedure for the generation of peptides with antioxidant capacity including the acquisition of crude peptides, the assessment of antioxidant activity, and the purification and identification of the active fraction. It remains critical to perform validation experiments with a cell model, animal model or clinical trial to eliminate safety concerns before final application in the food system. In addition, some of the common characteristics on structure-activity relationship are also reviewed based on the identified antioxidant peptides. PMID:27657142

  10. Atmospheric thermodynamics

    CERN Document Server

    Iribarne, J V

    1973-01-01

    The thermodynamics of the atmosphere is the subject of several chapters in most textbooks on dynamic meteorology, but there is no work in English to give the subject a specific and more extensive treatment. In writing the present textbook, we have tried to fill this rather remarkable gap in the literature related to atmospheric sciences. Our aim has been to provide students of meteorology with a book that can playa role similar to the textbooks on chemical thermodynamics for the chemists. This implies a previous knowledge of general thermodynamics, such as students acquire in general physics courses; therefore, although the basic principles are reviewed (in the first four chapters), they are only briefly discussed, and emphasis is laid on those topics that will be useful in later chapters, through their application to atmospheric problems. No attempt has been made to introduce the thermodynamics of irreversible processes; on the other hand, consideration of heterogeneous and open homogeneous systems permits a...

  11. Theoretical investigation on the atmospheric fate of CF3C(O)OCH 2O radical: alpha-ester rearrangement vs oxidation at 298 K.

    Science.gov (United States)

    Mishra, Bhupesh Kumar

    2014-09-01

    A theoretical study on the mechanism of the thermal decomposition of CF(3)C(O)OCH(2)O radical is presented for the first time. Geometry optimization and frequency calculations were performed at the MPWB1K/6-31 + G(d, p) level of theory and energetic information further refined by calculating the energy of the species using G2(MP2) theory. Three plausible decomposition pathways including α-ester rearrangement, reaction with O(2) and thermal decomposition (C-O bond scission) were considered in detail. Our results reveal that reaction with O(2) is the dominant path for the decomposition of CF(3)C(O)OCH(2)O radical in the atmosphere, involving the lowest energy barrier, which is in accord with experimental findings. Our theoretical results also suggest that α-ester rearrangement leading to the formation of trifluoroacetic acid TFA makes a negligible contribution to decomposition of the title alkoxy radical. The thermal rate constants for the above decomposition pathways were evaluated using canonical transition state theory (CTST) at 298 K. PMID:25208556

  12. Wastes and by-products - alternatives for agricultural use

    International Nuclear Information System (INIS)

    Top address a growing national problem with generation of wastes and by-products, TVA has been involved for several years with developing and commercializing environmentally responsible practices for eliminating, minimizing, or utilizing various wastes/by-products. In many cases, reducing waste generation is impractical, but the wastes/by-products can be converted into other environmentally sound products. In some instances, conversion of safe, value-added agricultural products in the best or only practical alternative. TVA is currently involved with a diversity of projects converting wastes/by-products into safe, economical, and agriculturally beneficial products. Environmental improvement projects have involved poultry litter, cellulosic wastes, used battery acid, ammonium sulfate fines, lead smelting effluents, deep-welled sulfuric acid/ammonium bisulfate solutions, wood ash, waste magnesium ammonium sulfate slurry from recording tape production, and ammunition plant waste sodium nitrate/ammonium nitrate streams

  13. Wastes and by-products - alternatives for agricultural use

    Energy Technology Data Exchange (ETDEWEB)

    Boles, J.L.; Craft, D.J.; Parker, B.R.

    1994-10-01

    Top address a growing national problem with generation of wastes and by-products, TVA has been involved for several years with developing and commercializing environmentally responsible practices for eliminating, minimizing, or utilizing various wastes/by-products. In many cases, reducing waste generation is impractical, but the wastes/by-products can be converted into other environmentally sound products. In some instances, conversion of safe, value-added agricultural products in the best or only practical alternative. TVA is currently involved with a diversity of projects converting wastes/by-products into safe, economical, and agriculturally beneficial products. Environmental improvement projects have involved poultry litter, cellulosic wastes, used battery acid, ammonium sulfate fines, lead smelting effluents, deep-welled sulfuric acid/ammonium bisulfate solutions, wood ash, waste magnesium ammonium sulfate slurry from recording tape production, and ammunition plant waste sodium nitrate/ammonium nitrate streams.

  14. Formation and Occurrence of Disinfection By-Products

    Science.gov (United States)

    Disinfection by-products (DBPs) are formed when disinfectants such as chlorine, ozone, chlorine dioxide, or chloramines react with naturally occurring organic matter, anthropogenic contaminants, bromide, and iodide during the production of drinking water. There is concern about D...

  15. SOA formation from the atmospheric oxidation of 2-methyl-3-buten-2-ol and its implications for PM2.5

    Directory of Open Access Journals (Sweden)

    W. A. Lonneman

    2012-02-01

    Full Text Available The formation of secondary organic aerosol (SOA generated by irradiating 2-methyl-3-buten-2-ol (MBO in the presence and/or absence of NOx, H2O2, and/or SO2 was examined. Experiments were conducted in smog chambers operated in either dynamic or static mode. A filter/denuder sampling system was used for simultaneously collecting gas- and particle-phase products. The structural characterization of gas and particulate products was investigated using BSTFA, BSTFA + PFBHA, and DNPH derivatization techniques followed by GC-MS and liquid chromatography analysis. This analysis showed the occurrence of more than 68 oxygenated organic compounds in the gas and particle phases, 28 of which were tentatively identified. The major components observed include 2,3-dihydroxyisopentanol (DHIP, 2-hydroxy-2-oxoisopentanol, 2,3-dihydroxy-3-methylbutanal, 2,3-dihydroxy-2-methylsuccinic acid, 2-hydroxy-2-methylpropanedioic acid, acetone, glyoxal, methylglyoxal, glycolaldehyde, and formaldehyde. Most of these oxygenated compounds were detected for the first time in this study. While measurements of the gas-phase photooxidation products have been made, the focus of this work has been an examination of the particle phase. SOA from some experiments was analyzed for the organic mass to organic carbon ratio (OM/OC, the effective enthalpy of vaporization (ΔHvapeff, and the aerosol yield. Additionally, aerosol size, volume, and number concentrations were measured by a Scanning Mobility Particle Sizer coupled to a Condensation Particle Counter system. The OM/OC ratio was 2.1 in the MBO/H2O2 system. The ΔHvapeff was 41 kJ mol−1, a value similar to that of isoprene SOA. The laboratory SOA yield measured in this study was 0.7% in MBO/H2O2 for an aerosol mass of 33 μg m−3. Secondary organic aerosol was found to be negligible under conditions with oxides of nitrogen (NOx present. Time profiles and proposed reaction schemes are provided for selected compounds. The contribution

  16. Antioxidant properties of extracts from buckwheat by-products

    OpenAIRE

    Marzanna Hęś; Danuta Górecka; Krzysztof Dziedzic

    2012-01-01

    Background. In the course of production of buckwheat groats by-products are produced, such as bran and hull, which apart from high content of dietary fi ber, may also constitute valuable sources of antioxidants. The aim of these investigations was to determine the antioxidant activity of extracts from by-products produced during processing of buckwheat for groats. Material and method. Analyses were conducted on bran and hull of buckwheat cv. Kora. Extraction was run using acetone, methanol an...

  17. Assessing methane oxidation under landfill covers and its contribution to the above atmospheric CO2 levels: The added value of the isotope (δ13C and δ18O CO2; δ13C and δD CH4) approach

    International Nuclear Information System (INIS)

    Highlights: ► Comparison of the isotope and mass balance approaches to evaluate the level of methane oxidation within a landfill. ► The level of methane oxidation is not homogenous under the landfill cover and is strongly correlated to the methane flux. ► Isotope tracking of the contribution of the methane oxidation to the CO2 concentrations in the ambient air. - Abstract: We are presenting here a multi-isotope approach (δ13C and δ18O of CO2; δ13C and δD of CH4) to assess (i) the level(s) of methane oxidation during waste biodegradation and its migration through a landfill cover in Sonzay (France), and (ii) its contribution to the atmospheric CO2 levels above the surface. The isotope approach is compared to the more conventional mass balance approach. Results from the two techniques are comparable and show that the CH4 oxidation under the landfill cover is heterogenous, with low oxidation percentages in samples showing high biogas fluxes, which was expected in clay covers presenting fissures, through which CH4 is rapidly transported. At shallow depth, more immobile biogas pockets show a higher level of CH4 oxidation by the methanotrophic bacteria. δ13C of CO2 samples taken at different heights (from below the cover up to 8 m above the ground level) were also used to identify and assess the relative contributions of its main sources both under the landfill cover and in the surrounding atmosphere.

  18. ANALYSIS OF BY-PRODUCTS MARKET IN RUSSIA

    Directory of Open Access Journals (Sweden)

    Keniyz N. V.

    2015-01-01

    Full Text Available Changing style of life, its rhythm and tendencies dictate their own conditions. The deficit of time makes us economize it on all, including the time for cooking. Among the main trends of the domestic meat market - switching consumers from frozen meat products to fresh cooled products. In connection with it the amount of consumers of meat semi-finished products grows. In the work there was considered the results of research of the Russian market of by-products. The market of frozen meat by-products is actively developed in large cities, where it has its own production. The participants of the market state that consumers have started to buy more frozen by-products by weight and the analysis of meat by-products assortment in retailing trade for 2014 testifies it. Trying to fasten their positions, operators of the market not only develop the production powers but work out new products and the analysis of dynamics of production volumes of meat by-products and shares of federal districts – producers of meat by-products testify it. The main players in this segment see the future market for complex, receipt, combined products and ready dishes that will lead to change of structure of meat semi-finished products sales

  19. Interpreting the Ultraviolet Aerosol Index Observed with the OMI Satellite Instrument to Understand Absorption by Organic Aerosols: Implications for Atmospheric Oxidation and Direct Radiative Effects

    Science.gov (United States)

    Hammer, Melanie S.; Martin, Randall V.; Donkelaar, Aaron van; Buchard, Virginie; Torres, Omar; Ridley, David A.; Spurr, Robert J. D.

    2016-01-01

    Satellite observations of the ultraviolet aerosol index (UVAI) are sensitive to absorption of solar radiation by aerosols; this absorption affects photolysis frequencies and radiative forcing. We develop a global simulation of the UVAI using the 3-D chemical transport model GEOSChem coupled with the Vector Linearized Discrete Ordinate Radiative Transfer model (VLIDORT). The simulation is applied to interpret UVAI observations from the Ozone Monitoring Instrument (OMI) for the year 2007. Simulated and observed values are highly consistent in regions where mineral dust dominates the UVAI, but a large negative bias (-0.32 to -0.97) exists between simulated and observed values in biomass burning regions. We determine effective optical properties for absorbing organic aerosol, known as brown carbon (BrC), and implement them into GEOS-Chem to better represent observed UVAI values over biomass burning regions. The inclusion of absorbing BrC decreases the mean bias between simulated and OMI UVAI values from -0.57 to -0.09 over West Africa in January, from -0.32 to +0.0002 over South Asia in April, from -0.97 to -0.22 over southern Africa in July, and from -0.50 to +0.33 over South America in September. The spectral dependence of absorption after including BrC in the model is broadly consistent with reported observations for biomass burning aerosol, with absorbing Angstrom exponent (AAE) values ranging from 2.9 in the ultraviolet (UV) to 1.3 across the UV-Near IR spectrum. We assess the effect of the additional UV absorption by BrC on atmospheric photochemistry by examining tropospheric hydroxyl radical (OH) concentrations in GEOS-Chem. The inclusion of BrC decreases OH by up to 30% over South America in September, up to 20% over southern Africa in July, and up to 15% over other biomass burning regions. Global annual mean OH concentrations in GEOS-Chem decrease due to the presence of absorbing BrC, increasing the methyl chloroform lifetime from 5.62 to 5.68 years, thus

  20. Interpreting the Ultraviolet Aerosol Index observed with the OMI satellite instrument to understand absorption by organic aerosols: implications for atmospheric oxidation and direct radiative effects

    Directory of Open Access Journals (Sweden)

    M. S. Hammer

    2015-10-01

    Full Text Available Satellite observations of the Ultraviolet Aerosol Index (UVAI are sensitive to absorption of solar radiation by aerosols; this absorption affects photolysis frequencies and radiative forcing. We develop a global simulation of the UVAI using the 3-D chemical transport model GEOS-Chem coupled with the Vector Linearized Discrete Ordinate Radiative Transfer model (VLIDORT. The simulation is applied to interpret UVAI observations from the Ozone Monitoring Instrument (OMI for the year 2007. Simulated and observed values are highly consistent in regions where mineral dust dominates the UVAI, but a large negative bias (−0.32 to −0.97 exists between simulated and observed values in biomass burning regions. We determine effective optical properties for absorbing organic aerosol, known as brown carbon (BrC, and implement them into GEOS-Chem to better represent observed UVAI values over biomass burning regions. The addition of absorbing BrC decreases the mean bias between simulated and OMI UVAI values from −0.57 to −0.09 over West Africa in January, from −0.32 to +0.0002 over South Asia in April, from −0.97 to −0.22 over southern Africa in July, and from −0.50 to +0.33 over South America in September. The spectral dependence of absorption after adding BrC to the model is broadly consistent with reported observations for biomass burning aerosol, with Absorbing Angstrom Exponent (AAE values ranging from 2.9 in the ultraviolet (UV to 1.3 across the UV-Near IR spectrum. We assess the effect of the additional UV absorption by BrC on atmospheric photochemistry by examining tropospheric hydroxyl radical (OH concentrations in GEOS-Chem. The inclusion of BrC decreases OH by up to 35 % over South America in September, up to 25 % over southern Africa in July, and up to 20 % over other biomass burning regions. Global annual mean OH concentrations in GEOS-Chem decrease due to the presence of absorbing BrC, increasing the methyl chloroform lifetime from 5

  1. Atmospheric Refraction

    CERN Document Server

    Nauenberg, Michael

    2016-01-01

    Calculations of atmospheric refraction are generally based on a simplified model of atmospheric density in the troposphere which assumes that the temperature decreases at a constant lapse rate from sea level up to a height equal to eleven km, and that afterwards it remains constant. In this model, the temperature divided by the lapse rate determines the length scale in the calculations for altitudes less than this height. But daily balloon measurements across the U.S.A. reveal that in some cases the air temperature actually increases from sea level up to a height of about one km, and only after reaching a plateau, it decreases at an approximately constant lapse rate. Moreover, in three examples considered here, the temperature does not remain constant at eleven km , but continues to decreases to a minimum at about sixteen kilometers , and then increases at higher altitudes at a lower rate. Calculations of atmospheric refraction based on this atmospheric data is compared with the results of simplified models.

  2. Atmospheric Dispositifs

    DEFF Research Database (Denmark)

    Wieczorek, Izabela

    2015-01-01

    as a spatial phenomenon, exploring a multiplicity of conditions that constitute their resonant origins – i.e. the production sites from and within they have emerged. The intention is also to argue that despite the fact that atmosphere as an aesthetic category has crystallised over the last few decades...

  3. Highly oxidized superconductors

    Science.gov (United States)

    Morris, Donald E.

    1994-01-01

    Novel superconducting materials in the form of compounds, structures or phases are formed by performing otherwise known syntheses in a highly oxidizing atmosphere rather than that created by molecular oxygen at atmospheric pressure or below. This leads to the successful synthesis of novel superconducting compounds which are thermodynamically stable at the conditions under which they are formed.

  4. Drinking Water Disinfection by In-line Electrolysis: Product and Inorganic By-Product Formation

    Science.gov (United States)

    Bergmann, M. E. Henry

    This section covers peculiarities of so-called in-line electrolysis when drinking water is electrolysed to produce disinfection species killing microorganisms. Mainly mixed oxide electrodes (MIO) based on IrO2 and/or RuO2 coatings and boron-doped diamond electrodes were used in the studies. Artificial and real drinking water systems were electrolysed in continuous and discontinuous operating mode, varying water composition, current density and electrode materials. Results show, besides the ability of producing active chlorine, risks of inorganic disinfection by-products (DBPs) such as chlorate, perchlorate, nitrite, ammonium, chloramines, hydrogen peroxide and others. DBPs are responsible for analysis errors using DPD method for active chlorine measurements. Geometry may influence by-product yield. As a conclusion, the necessity of developing test routines for practical cell applications must be underlined.

  5. Oxidization of squalene, a human skin lipid: a new and reliable marker of environmental pollution studies.

    Science.gov (United States)

    Pham, D-M; Boussouira, B; Moyal, D; Nguyen, Q L

    2015-08-01

    A review of the oxidization of squalene, a specific human compound produced by the sebaceous gland, is proposed. Such chemical transformation induces important consequences at various levels. Squalene by-products, mostly under peroxidized forms, lead to comedogenesis, contribute to the development of inflammatory acne and possibly modify the skin relief (wrinkling). Experimental conditions of oxidation and/or photo-oxidation mechanisms are exposed, suggesting that they could possibly be bio-markers of atmospheric pollution upon skin. Ozone, long UVA rays, cigarette smoke… are shown powerful oxidizing agents of squalene. Some in vitro, ex vivo and in vivo testings are proposed as examples, aiming at studying ingredients or products capable of boosting or counteracting such chemical changes that, globally, bring adverse effects to various cutaneous compartments. PMID:25656265

  6. Oxidization of squalene, a human skin lipid: a new and reliable marker of environmental pollution studies.

    Science.gov (United States)

    Pham, D-M; Boussouira, B; Moyal, D; Nguyen, Q L

    2015-08-01

    A review of the oxidization of squalene, a specific human compound produced by the sebaceous gland, is proposed. Such chemical transformation induces important consequences at various levels. Squalene by-products, mostly under peroxidized forms, lead to comedogenesis, contribute to the development of inflammatory acne and possibly modify the skin relief (wrinkling). Experimental conditions of oxidation and/or photo-oxidation mechanisms are exposed, suggesting that they could possibly be bio-markers of atmospheric pollution upon skin. Ozone, long UVA rays, cigarette smoke… are shown powerful oxidizing agents of squalene. Some in vitro, ex vivo and in vivo testings are proposed as examples, aiming at studying ingredients or products capable of boosting or counteracting such chemical changes that, globally, bring adverse effects to various cutaneous compartments.

  7. Impact of Amazonian deforestation on atmospheric chemistry

    OpenAIRE

    Ganzeveld, L.N.; Lelieveld, J.

    2004-01-01

    A single-column chemistry and climate model has been used to study the impact of deforestation in the Amazon Basin on atmospheric chemistry. Over deforested areas, daytime ozone deposition generally decreases strongly except when surface wetness decreases through reduced precipitation, whereas nocturnal soil deposition increases. The isoprene and soil nitric oxide emissions decrease although nitrogen oxide release to the atmosphere increases due to reduced canopy deposition. Deforestation als...

  8. Atmospheric emission of nitrogen oxide from kraft recovery boilers in Sweden; Kartlaeggning av NO{sub x}-utslaepp fraan sodapannor i Sverige

    Energy Technology Data Exchange (ETDEWEB)

    Kjoerk, Anders; Herstad Swaerd, Solvie [S.E.P. Scandinavian Energy Project AB, Goeteborg (Sweden)

    2000-05-01

    Recovery boiler NO{sub x} emissions are low compared with those from power boilers. However tighter environmental requirements to decrease the acidic emissions implies that all sources have to be addressed. There are an ongoing evaluation and development of NO{sub x} control technologies in the pulp industry. Basically air staging, selective catalytic reduction, SCR, and selective noncatalytic reduction, SNCR, have been discussed. Other NO{sub x} control options may be available as a result of ongoing research and development. As a background in the work to reduce the acid rain it has been considered necessary to have a good picture of the NO{sub x} emission from recovery boilers, and the Thermal Engineering Research Institute in Sweden have therefore sponsored this study. The intention is to give a good general view and try to explain the reasons for the large differences between boilers. Data from the 30 kraft recovery boilers which were in operation in Sweden during 1999 have been collected. Both NO{sub x} levels and specific conditions which could have an influence on the level have been included. The evaluation show a clear correlation between the nitrogen content in the liquor and the NO{sub x} level. It seams also that a long retention time in the furnace give an opportunity to reduce the amount of nitrogen oxide. For most boilers in Sweden the NO{sub x} levels are reported in mg/MJ and comparison could be done between different types of boilers. However for recovery boilers there could be a large uncertainty in the calculation which gives the amount (mg) of NO{sub x}, the definition of the heat input to be used (MJ) is either not clear. As a base for the study the measured concentration in ppm is used instead. The reported values are in the range of 30 - 100 ppm, however the majority of the boilers operate in a more narrow range 60-80 ppm. Air staging and other combustion methods could not reasonably reduce the NO{sub x} emission with more than 20% in the

  9. Atmospheric Chemistry and Air Pollution

    Directory of Open Access Journals (Sweden)

    Jeffrey S. Gaffney

    2003-01-01

    Full Text Available Atmospheric chemistry is an important discipline for understanding air pollution and its impacts. This mini-review gives a brief history of air pollution and presents an overview of some of the basic photochemistry involved in the production of ozone and other oxidants in the atmosphere. Urban air quality issues are reviewed with a specific focus on ozone and other oxidants, primary and secondary aerosols, alternative fuels, and the potential for chlorine releases to amplify oxidant chemistry in industrial areas. Regional air pollution issues such as acid rain, long-range transport of aerosols and visibility loss, and the connections of aerosols to ozone and peroxyacetyl nitrate chemistry are examined. Finally, the potential impacts of air pollutants on the global-scale radiative balances of gases and aerosols are discussed briefly.

  10. 常压下Pt-Bi双金属催化剂上甘油选择性氧化%Glycerol Oxidation with Oxygen over Bimetallic Pt-Bi Catalysts under Atmospheric Pressure

    Institute of Scientific and Technical Information of China (English)

    梁丹; 崔世玉; 高静; 王军华; 陈平; 侯昭胤

    2011-01-01

    制备了一系列活性碳(AC)负载的Pt-Bi双金属催化剂,考察了催化剂中Bi含量对其催化甘油选择性氧化反应性能的影响.结果表明,适量Bi的添加可以改善催化剂中Pt的氧化还原性能,从而有利于催化剂活性的提高和二羟基丙酮(DIHA)产物的生成.当Bi的含量为5%时,该催化剂的活性最高,甘油转化率和DIHA选择性分别达到91.5%和49.0%.表征结果显示,Pt-Bi颗粒的平均粒径为3.8 nm,且高度分散在催化剂表面,这是该催化剂具有较高活性的主要原因.%A series of bimetallic Pt-Bi catalysts with a constant platinum content of 5.0 wt% and a varied bismuth content (3.0-7.0 wt%)supported on active carbon were prepared and used for glycerol oxidation with oxygen under atmospheric pressure.The bimetallic Pt-Bi/C was efficient for the selective oxidation of glycerol to dihydroxyacetone (DIHA) and the selectivity for DIHA reached 49.0% at a 91.5%conversion of glycerol over the 5%Pt-5%Bi/C catalyst.X-ray diffraction and transmission electron microscopy analysis revealed that the specially configured Pt-Bi nanoparticles in 5%Pt-5%Bi/C were highly dispersed (3.8 nm) over the active carbon support,which is proposed to contribute to the improved performance.

  11. Processes regulating nitric oxide emissions from soils

    DEFF Research Database (Denmark)

    Pilegaard, Kim

    2013-01-01

    Nitric oxide (NO) is a reactive gas that plays an important role in atmospheric chemistry by influencing the production and destruction of ozone and thereby the oxidizing capacity of the atmosphere. NO also contributes by its oxidation products to the formation of acid rain. The major sources...

  12. Estimating indirect land use impacts from by-products utilization

    Energy Technology Data Exchange (ETDEWEB)

    Croezen, H.; Brouwer, F.

    2008-06-15

    Aim of this project part is providing an indication of the effects utilization of by-products from biofuels production can have on global land use and on land use changes. Potential influences on land use changes may also influence net GHG emissions, in case deforestation or other forms of changing natural habitats into crop land are avoided. In order to demonstrate the relevance we broadly translated avoided land use in potential GHG emission avoidance due to avoiding land use change. The analysis focuses on the utilization of by-products from so-called first generation biofuels production technologies as feed. This application avoids cultivation of primary feed crops such as soy, wheat and corn and thus reduces area requirement for cultivation of these crops and the GHG emissions related to crop cultivation and crop processing. Reduction in area requirement might also mean avoiding creation of extra agricultural area by transforming natural area's. This would avoid GHG emissions related to land use change. The by-products could alternatively be utilized as fuel or - in the future - as feedstock for second generation biofuels. By-products utilization as fuel will avoid fossil fuel consumption and related GHG emissions. The analysis is a follow up of the E4Tech scenario analysis. We used the amounts of crops applied as feedstocks in the E4Tech scenario's as starting point of our own analysis. In chapter 2 we estimate the amounts of by-products we have to consider. In chapter 3 we then estimate which amounts of primary feed crops are likely to be replaced by the considered amounts of by-products.

  13. Producing Fish Protein Hydrolysates from Mackerel By-Products

    OpenAIRE

    Ana Luísa De Sousa Augusto

    2014-01-01

    Portugal is one of the largest consumers of fishery products in Europe. This consumption involves a large amount of discarded raw material, such as rejected fish in selling auctions and the generation of by-products in industrial production processes. The by-products in the canning industry alone reach 40% of the raw material, while the frozen fish industries may reach 10-50% of the raw material (INE, 2013). Fish protein hydrolysates (FPH) are one of the most promising technologies for th...

  14. Strategies For Turkish Automotive By-Products Industry

    Directory of Open Access Journals (Sweden)

    Hakan Bütüner

    2012-06-01

    Full Text Available Automotive industry is comprised of the industry which produces vehicles, and the industry which, as dominated by Small and Medium Scale Enterprises, produces parts, modules, and systems of such vehicles according to the technical documentation. Having been established through technical and economic supports of the major manufacturers, and developed in the course of time, the by products industry is involved its activities as a significant potential for the domestic economy at present. In this article, general characteristics of Turkish automative by products industry, its weak aspects, aspects need to be improved, and dominant strategies that need to be considered for the improvement are discussed.

  15. Atmospheric soundings from Mount Abu

    Science.gov (United States)

    Sharma, Som; Sinha, H. S. S.

    2005-06-01

    An atmospheric science laboratory was set up at Gurushikhar, in the campus of PRL's Infrared observatory, in 1994. A variety of scientific instruments were housed in the atmospheric science laboratory to explore the Earth's ionosphere and neutral atmosphere. A powerful Nd-YAG laser based Lidar, a multi-wavelength all sky imaging system, Day-night-airglow photometer/spectrometer and a proton precession magnetometer are in operation along with a surface ozone sampler, a carbon mono-oxide analyzer and a UV radiometer (measures solar ultraviolet irradiance between 280 and 320 nm). This article highlights the neutral density and temperature measurements by the lidar as well as Atmospheric/Ionospheric parameters derived by other instruments.

  16. Total Sulfur Deposition (wet+dry) from the Atmosphere

    Data.gov (United States)

    U.S. Environmental Protection Agency — Sulfur Dioxide (SO2) is emitted primarily as a by-product of coal combustion from power plants. Sulfur Dioxide reacts in the atmosphere to form other chemical such...

  17. Nutritional Value of Irradiated Animal Feed By-Products

    International Nuclear Information System (INIS)

    Animal feed by-products, widely used in animal diets, are sources of disease organisms for animals and for human beings. Salmonella is the principal genus of concern.Radiation treatment (radicidation, radurization) is a promising method of decontamination of feed ingredients. Commercial samples of fish, meat, and blood meals were sealed by heat in polyethylene bags and irradiated at dose levels of 5.0, 10, 20 and 50 kGy. Their chemical analysis were carried out according to A. O. A.C [1] and the total protein efficiency (TPE) of the three animal feed by-products was determined according to Wood ham (2) by using one day old Dokki-4 chicks. Radiation induced an insignificant effect on the chemical constituent of meals. Also, the same trend was observed with TPE of both fish and meat meals. However, irradiation treatments improved TPE values of irradiated blood meal samples. From the results, it could be concluded that irradiation of animal feed by-products up to a dose level of 50 Gy has no adverse effects on the nutritional value of animal feed by-products

  18. REDUCTION OF DISINFECTION BY-PRODUCT PERCURSORS BY NANOFILTRATION

    Science.gov (United States)

    The reduction of disinfection by-product (DBP) precursors by nanofiltration was investigated in Florida at both a groundwater site and a surface water site. eparate studies, involving pilot plant operations, were conducted for one year at each site. he principal research tasks at...

  19. Maximizing Utilization of Energy from Crop By-products

    Directory of Open Access Journals (Sweden)

    Budi Haryanto

    2014-03-01

    Full Text Available The availability of crop by-products is huge during harvesting times as related to the vast agricultural land area; however, their utilization is still limited due to lack of knowledge and handling problem. Seasonal effect is obvious especially during wet season when high rainfall hinders proper management of crop by-products. Crop by-products are energy rich feedstuffs in the form of chemical substance such as cellulose and hemicellulose. The utilization of cellulose and hemicellulose as sources of energy can be maximized by the application of technologies to increase the digestibility. Cellulose is polymer of glucose while hemicellulose is polymer of xylose which both can be converted to volatile fatty acids by rumen microbial enzyme activities and subsequently used by the host animal as source of energy. In addition, cellulose and hemicellulose can also be used as substrates for bioethanol production leaving behind residual matter with higher concentration of protein which is also appropriate for ruminant feeds. The fat content of crop by-products such as those in rice bran and corn germ can be extracted for oil production that can be used for human consumption with concomitant production of high nutritive value of residues for ruminant feeds. The oil extraction technologies are available; however the high cost of ethanol and oil production should obtain high attention to make the technologies more applicable at farmers’ level.

  20. Genotoxicity of Disinfection By-products: Comparison to Carcinogenicity

    Science.gov (United States)

    Disinfection by-products (DBPs) can be formed when water is disinfected by various agents such as chlorine, ozone, or chloramines. Among the >600 DBPs identified in drinking water, 11 are regulated by the U.S. Environmental Protection Agency, and another ~70 DBPs that occur at s...

  1. Impacts of drinking water pretreatments on the formation of nitrogenous disinfection by-products.

    Science.gov (United States)

    Chu, Wenhai; Gao, Naiyun; Deng, Yang; Templeton, Michael R; Yin, Daqiang

    2011-12-01

    The formation of disinfection by-products (DBPs), including both nitrogenous DBPs (N-DBPs) and carbonaceous DBPs (C-DBPs), was investigated by analyzing chlorinated water samples following the application of three pretreatment processes: (i) powdered activated carbon (PAC) adsorption; (ii) KMnO(4) oxidation and (iii) biological contact oxidation (BCO), coupled with conventional water treatment processes. PAC adsorption can remove effectively the precursors of chloroform (42.7%), dichloroacetonitrile (28.6%), dichloroacetamide (DCAcAm) (27.2%) and trichloronitromethane (35.7%), which were higher than that pretreated by KMnO(4) oxidation and/or BCO process. The removal efficiency of dissolved organic carbon by BCO process (76.5%)--was superior to that by PAC adsorption (69.9%) and KMnO(4) oxidation (61.4%). However, BCO increased the dissolved organic nitrogen (DON) concentration which caused more N-DBPs to be formed during subsequent chlorination. Soluble microbial products including numerous DON compounds were produced in the BCO process and were observed to play an essential role in the formation of DCAcAm in particular. PMID:22014706

  2. Ozone and hydrogen peroxide applications for disinfection by-products control in drinking water

    International Nuclear Information System (INIS)

    A great interest has been developed during the last years for ozone in drinking water treatments thanks to its strong oxidant and disinfectant power and for its efficiency in disinfection by-products (DBPs) precursors removal. However ozonization produces some specific DBPs, such as aldehydes and ketones; moreover, the presence of bromide in raw water engages ozone in a complex cycle in which both organic bromide and inorganic bromate are end products. In this paper the combination of hydrogen peroxide with ozone (known as peroxone process) and the ozone alone process were experimented on one surface water coming from the lake of Brugneto (Genova) in order to investigate bromate formation and trihalomethanes precursors removal during the oxidation process. The results show that the advanced peroxone process can be applied for bromate reduction (about 30-40%) with better results in comparison with the ozone alone process, while no advantages are shown for THMs precursors removal. The addition of in-line filtration step after pre-oxidation improves both bromate and THMs precursors removal, particularly with increasing hydrogen peroxide/ozone ratio in the oxidation step

  3. Land application uses for dry FGD by-products

    Energy Technology Data Exchange (ETDEWEB)

    Bigham, J.; Dick, W.; Forster, L.; Hitzhusen, F.; McCoy, E.; Stehouwer, R.; Traina, S.; Wolfe, W. (Ohio State Univ., Columbus, OH (United States)); Haefner, R. (Geological Survey, Columbus, OH (United States). Water Resources Div.)

    1993-04-01

    The 1990 amendments to the Clean Air Act have spurred the development of flue gas desulfurization (FGD) processes, several of which produce a dry, solid by-product material consisting of excess sorbent, reaction products containing sulfates and sulfites, and coal fly ash. Presently FGD by-product materials are treated as solid wastes and must be landfilled. However, landfill sites are becoming more scarce and tipping fees are constantly increasing. It is, therefore, highly desirable to find beneficial reuses for these materials provided the environmental impacts are minimal and socially acceptable. Phase 1 results of a 4 and 1/2 year study to demonstrate large volume beneficial uses of FGD by-products are reported. The purpose of the Phase 1 portion of the project was to characterize the chemical, physical, mineralogical and engineering properties of the FGD by-product materials obtained from various FGD technologies being developed in the state of Ohio. Phase 1 also involved the collection of baseline economic data related to the beneficial reuse of these FGD materials. A total of 58 samples were collected and analyzed. In summary Phase 1 results revealed that FGD by-product materials are essentially coal fly ash materials diluted with unreacted sorbent and reaction products. High volume beneficial reuses will depend on the economics of their substituting for existing materials for various types of applications (e.g. as an agricultural liming material, soil borrow for highway embankment construction, and reclamation of active and abandoned surface coal mines). Environmental constraints to the beneficial reuse of dry FGD byproduct materials, based on laboratory and leachate studies, seem to be less than for coal fly ash.

  4. Does KMnO4 preoxidation reduce the genotoxicity of disinfection by-products?

    Science.gov (United States)

    Chang, Yangyang; Bai, Yaohui; Qu, Jiuhui

    2016-11-01

    Potassium permanganate (KMnO4) preoxidation is capable of affecting the formation of disinfection by-products (DBPs). However, few studies have focused on the toxicity of DBPs after KMnO4 preoxidation, which is an important index to evaluate alternative treatment processes. Herein genotoxicity (SOS/umu test) was used to clarify the impact of KMnO4 preoxidation on the chlorination byproducts produced from two representative precursors, tyrosine (Tyr) and 2-hydroxy-4-methoxybenzophenone-5-sulfonic acid (BP-4), and their mixture. Results revealed that although KMnO4 could not oxidize BP-4, after chlorination KMnO4 could oxidize the chlorination byproducts of BP-4 and thus decrease the genotoxicity production. For Tyr, KMnO4 preoxidation could increase or decrease the genotoxicity of DBPs, depending on the KMnO4 dose. The optimal initial molar ratio of KMnO4 to Tyr was confirmed to be 1:1. It has been proved that both the oxidation of Tyr by KMnO4 and manganese dioxide (MnO2, the reduction product of KMnO4) and the oxidation of chlorination byproducts by MnO2 can decrease the genotoxicity production of chlorinated Tyr. Remarkably, during chlorination, the competition of manganese(II) oxidation with organic oxidation can result in less chlorine reacting with organics, to induce an increase in genotoxicity. This is the main cause for the increase in genotoxicity of chlorinated Tyr after KMnO4 preoxidation. Additionally, the genotoxicity of the chlorinated mixture was shifted from being higher than the sum of individual genotoxicities of the chlorinated precursors to being lower than their sum with increasing KMnO4 dosage, due to the combined effects between the preoxidation-chlorination products from the two compounds. PMID:27521641

  5. Bioassay-guided fractionation of a hepatoprotective and antioxidant extract of pea by-product.

    Science.gov (United States)

    Seida, Ahmed A; El Tanbouly, Nebal D; Islam, Wafaa T; Eid, Hanaa H; El Maraghy, Shohda A; El Senousy, Amira S

    2015-01-01

    The hepatoprotective and antioxidant activities of the hydroalcoholic extract (PE) of pea (Pisum sativum L.) by-product were evaluated, using CCl4-induced oxidative stress and hepatic damage in rats. These activities were assessed via measuring alanine aminotransferase (ALT), aspartate aminotransferase (AST), total protein and albumin, malondialdehyde (MDA), reduced glutathione (GSH), protein thiols (PSH), nitrite/nitrate levels, glutathione-peroxidase (GSH-Px), glutathione-S-transferase (GST) activities, as well as, histopathological evaluation. PE revealed significant hepatoprotective and antioxidant activities mostly found in n-butanol fraction. Chromatographic fractionation of this active fraction led to the isolation of five flavonoid glycosides namely, quercetin-3-O-sophorotrioside (1), quercetin-3-O-rutinoside (2), quercetin-3-O-(6″″-O-E sinapoyl)-sophorotrioside (3), quercetin-3-O-(6″″-O-E feruloyl)-sophorotrioside (4) and quercetin-3-O-β-D-glucopyranoside (5). The isolated compounds were quantified in PE, using a validated HPLC method and the nutritional composition of pea by-product was also investigated. Our results suggest that pea by-product contained biologically active constituents which can be utilised to obtain high value added products for nutraceutical use.

  6. Atmospheric influence of Earth's earliest sulfur cycle

    Science.gov (United States)

    Farquhar; Bao; Thiemens

    2000-08-01

    Mass-independent isotopic signatures for delta(33)S, delta(34)S, and delta(36)S from sulfide and sulfate in Precambrian rocks indicate that a change occurred in the sulfur cycle between 2090 and 2450 million years ago (Ma). Before 2450 Ma, the cycle was influenced by gas-phase atmospheric reactions. These atmospheric reactions also played a role in determining the oxidation state of sulfur, implying that atmospheric oxygen partial pressures were low and that the roles of oxidative weathering and of microbial oxidation and reduction of sulfur were minimal. Atmospheric fractionation processes should be considered in the use of sulfur isotopes to study the onset and consequences of microbial fractionation processes in Earth's early history.

  7. Atmospheric pseudohalogen chemistry

    Directory of Open Access Journals (Sweden)

    D. J. Lary

    2004-09-01

    Full Text Available There are at least three reasons why hydrogen cyanide is likely to be significant for atmospheric chemistry. The first is well known, HCN is a product and marker of biomass burning. However, if a detailed ion chemistry of lightning is considered then it is almost certain than in addition to lightning producing NOx, it also produces HOx and HCN. Unlike NOx and HOx, HCN is long-lived and could therefore be a useful marker of lightning activity. Observational evidence is considered to support this view. Thirdly, the chemical decomposition of HCN leads to the production of small amounts of CN and NCO. NCO can be photolyzed in the visible portion of the spectrum yielding N atoms. The production of N atoms is significant as it leads to the titration of nitrogen from the atmosphere via N+N→N2. Normally the only modelled source of N atoms is NO photolysis which happens largely in the UV Schumann-Runge bands. However, NCO photolysis occurs in the visible and so could be involved in titration of atmospheric nitrogen in the lower stratosphere and troposphere. HCN emission inventories are worthy of attention. The CN and NCO radicals have been termed pseudohalogens since the 1920s. They are strongly bound, univalent, radicals with an extensive and varied chemistry. The products of the atmospheric oxidation of HCN are NO, CO and O3. N+CH4 and N+CH3OH are found to be important sources of HCN. Including the pseudohalogen chemistry gives a small increase in ozone and total reactive nitrogen (NOy.

  8. Disinfection by-products in ballast water treatment: an evaluation of regulatory data.

    Science.gov (United States)

    Werschkun, Barbara; Sommer, Yasmin; Banerji, Sangeeta

    2012-10-15

    To reduce the global spread of invasive aquatic species, international regulations will soon require reductions of the number of organisms in ballast water discharged by ships. For this purpose, ballast water treatment systems were developed and approved by an international procedure. These systems rely on established water treatment principles which, to different degrees, have been proven to generate disinfection by-products with hazardous properties but have only scarcely been investigated in marine environments. Our study evaluates the publicly available documentation about approved ballast water treatment systems with regard to by-product formation. The most commonly employed methods are chlorination, ozonation, and ultraviolet (UV) irradiation. Chlorination systems generate trihalomethanes, halogenated acetic acids, and bromate in substantially larger quantities than reported for other areas of application. Levels are highest in brackish water, and brominated species predominate, in particular bromoform and dibromoacetic acid. Ozonation, which is less frequently utilized, produces bromoform in lower concentrations but forms higher levels of bromate, both of which were effectively reduced by active carbon treatment. In systems based on UV radiation, medium pressure lamps are employed as well as UV-induced advanced oxidation. For all UV systems, by-product formation is reported only occasionally. The most notable observations were small increases in nitrite, hydrogen peroxide, halogenated methanes and acetic acids. The assessment of by-product formation during ballast water treatment is limited by the lacking completeness and quality of available information. This concerns the extent and statistical characterisation of chemical analysis as well as the documentation of the test water parameters.

  9. Energy applications of olive-oil industry by-products: 1. The exhaust foot cake

    Energy Technology Data Exchange (ETDEWEB)

    Masghouni, M. [Ecole Nationale des Ingenieurs de Tunis, Belvedere (Tunisia). Laboratoire de synthese et d' analyse des materiaux; Hassairi, M. [Ecole Nationale des Ingenieurs de Tunis, Belvedere (Tunisia). Laboratoire de thermique industrielle

    2000-07-01

    The energy characteristics of the exhaust foot cake (EFC) from the olive-oil extraction industry are described in this paper. This biomass has proved to be an interesting energy source. The use of this solid-waste as a combustible in brick manufacture is economically profitable: 1100 tons of EFC yearly substitute 420 EOT of No. 2 heavy fuel containing 4% of sulphur. The use of this solid-waste as an energy source is environment friendly, as it reduces the nuisance of solid-waste and gas emissions to the atmosphere, particularly sulphur oxides. (author)

  10. Utilization of biodiesel by-products for mosquito control.

    Science.gov (United States)

    Pant, Megha; Sharma, Satyawati; Dubey, Saurabh; Naik, Satya Narayan; Patanjali, Phool Kumar

    2016-03-01

    The current paper has elaborated the efficient utilization of non-edible oil seed cakes (NEOC), by-products of the bio-diesel extraction process to develop a herbal and novel mosquitocidal composition against the Aedes aegypti larvae. The composition consisted of botanical active ingredients, inerts, burning agents and preservatives; where the botanical active ingredients were karanja (Pongamia glabra) cake powder and jatropha (Jatropha curcas) cake powder, products left after the extraction of oil from karanja and jatropha seed. The percentage mortality value recorded for the combination with concentration, karanja cake powder (20%) and jatropha cake powder (20%), 1:1 was 96%. The coil formulations developed from these biodiesel by-products are of low cost, environmentally friendly and are less toxic than the synthetic active ingredients. PMID:26296531

  11. The origins of religion: evolved adaptation or by-product?

    Science.gov (United States)

    Pyysiäinen, Ilkka; Hauser, Marc

    2010-03-01

    Considerable debate has surrounded the question of the origins and evolution of religion. One proposal views religion as an adaptation for cooperation, whereas an alternative proposal views religion as a by-product of evolved, non-religious, cognitive functions. We critically evaluate each approach, explore the link between religion and morality in particular, and argue that recent empirical work in moral psychology provides stronger support for the by-product approach. Specifically, despite differences in religious background, individuals show no difference in the pattern of their moral judgments for unfamiliar moral scenarios. These findings suggest that religion evolved from pre-existing cognitive functions, but that it may then have been subject to selection, creating an adaptively designed system for solving the problem of cooperation.

  12. Utilization of biodiesel by-products for mosquito control.

    Science.gov (United States)

    Pant, Megha; Sharma, Satyawati; Dubey, Saurabh; Naik, Satya Narayan; Patanjali, Phool Kumar

    2016-03-01

    The current paper has elaborated the efficient utilization of non-edible oil seed cakes (NEOC), by-products of the bio-diesel extraction process to develop a herbal and novel mosquitocidal composition against the Aedes aegypti larvae. The composition consisted of botanical active ingredients, inerts, burning agents and preservatives; where the botanical active ingredients were karanja (Pongamia glabra) cake powder and jatropha (Jatropha curcas) cake powder, products left after the extraction of oil from karanja and jatropha seed. The percentage mortality value recorded for the combination with concentration, karanja cake powder (20%) and jatropha cake powder (20%), 1:1 was 96%. The coil formulations developed from these biodiesel by-products are of low cost, environmentally friendly and are less toxic than the synthetic active ingredients.

  13. Soil surface properties affected by organic by-products

    OpenAIRE

    Pachepsky Ya.A.; Rawls W.J.; Fournier L.L.; Filgueira R.R.; Sikora L.J.

    2002-01-01

    The beneficial effects of amending soils with organic by-products include improvement of both chemical and physical factors. Very few studies have investigated changes in the soil specific surface area (SSA) after amendments with manures or composts. Soil samples were taken from plots before and after four years� application of manures, composts or nitrogen fertilizer. A corn-wheat-soybean rotation was grown. Soil samples were tested for changes in water retention at �15 bar, bu...

  14. By-products from Fish Processing: Focus on French Industry

    OpenAIRE

    Penven, Anais; Perez-galvez, Raul; Berge, Jean-pascal

    2013-01-01

    Biotechnology advances for marine by-products conversion into products of interest are numerous. In order to give maximum elements of understanding, it is essential to define the framework of this research to understand why and how bioconversion technologies are applicable. It is essential to look beyond the technical and technological advances on the subject and so to take into account the economic, social, political and environmental parameters, which govern all forms of approaches for fish...

  15. Health impact of disinfection by-products in swimming pools

    OpenAIRE

    Villanueva, Cristina M.; Laia Font-Ribera

    2012-01-01

    This article is focused on the epidemiological evidence on the health impacts related to disinfection by-products (DBPs) in swimming pools, which is a chemical hazard generated as an undesired consequence to reduce the microbial pathogens. Specific DBPs are carcinogenic, fetotoxic and/or irritant to the airways according to experimental studies. Epidemiological evidence shows that swimming in pools during pregnancy is not associated with an increased risk of reproductive outcomes. An epidemio...

  16. Effect of Celebrity Endorsement in Advertising Activities by Product Type

    OpenAIRE

    Karasiewicz Grzegorz; Kowalczuk Martyna

    2014-01-01

    This article seeks to answer two related questions: are celebrity endorsements more likely to be result in a higher evaluation of the product being advertised than use of an anonymous individual (e.g. a typical consumer); and, if present, do these positive effects vary by product category? To answer these two questions research was conducted on a 237 student sample employing a quasi-experiment consisting of four groups (two product categories and two types of endorsers) using data collected t...

  17. Radiolytic oxidation

    International Nuclear Information System (INIS)

    Work under the Radiolytic Oxidation Contract from 1986 until April 1989 is reported. The effects of alpha- and gamma-irradiation on the chemistries of plutonium, neptunium and technetium, under conditions representative of the near fields of intermediate and high level waste repositories, were investigated. Gamma-radiolysis of Np (IV) results in oxidation in solutions below pH 12. Solutions of Tc (VII) are reduced to Tc (IV) by gamma-irradiation in contact with blast furnace slag/ordinary Portland cement under an inert atmosphere but not when in contact with pulverized fuel ash/ordinary Portland cement. Tc (IV) is shown to be susceptible to oxidation by the products of the alpha-radiolysis of water. The results of 'overall effects' experiments, which combined representative components of typical ILW or HLW near fields, supported these observations and also showed enhanced plutonium concentrations in alpha-irradiated, HLW simulations. Mathematical models of the behaviour of plutonium and neptunium during gamma-radiolysis have been developed and indicate that oxidation to Pu (VI) is possible at dose rates typical of those expected for HLW. Simulations at ILW dose rates have indicated some effect upon the speciation of neptunium. Laboratory studies of the gamma-irradiation of Np (IV) in bentonite-equilibrated water have also been modelled. Computer code used: PHREEQE, 8 Figs.; 48 Tabs.; 38 refs

  18. New insights into meat by-product utilization.

    Science.gov (United States)

    Toldrá, Fidel; Mora, Leticia; Reig, Milagro

    2016-10-01

    Meat industry generates large volumes of by-products like blood, bones, meat trimmings, skin, fatty tissues, horns, hoofs, feet, skull and viscera among others that are costly to be treated and disposed ecologically. These costs can be balanced through innovation to generate added value products that increase its profitability. Rendering results in feed ingredients for livestock, poultry and aquaculture as well as for pet foods. Energy valorization can be obtained through the thermochemical processing of meat and bone meal or the use of waste animal fats for the production of biodiesel. More recently, new applications have been reported like the production of polyhydroxyalkanoates as alternative to plastics produced from petroleum. Other interesting valorization strategies are based on the hydrolysis of by-products to obtain added value products like bioactive peptides with relevant physiological effects as antihypertensive, antioxidant, antidiabetic, antimicrobial, etc. with promising applications in the food, pharmaceutical and cosmetics industry. This paper reports and discusses the latest developments and trends in the use and valorisation of meat industry by-products. PMID:27156911

  19. Irradiated fuel by-product separation research in Canada

    International Nuclear Information System (INIS)

    Although no decision has been made to reprocess irradiated CANDU fuel, by-product separation research has recently been initiated in Canada because of its potential importance to Canadian research programs in advanced fuel cycles (especially U/Pu cycle development in the near term) and nuclear waste management. In addition, separated by-products could have a significant commercial potential. Demonstrated applications include: heat sources, gamma radiation sources, light sources, new materials for productions of other useful isotopes, etc. For illustrative purposes the calculated market value of by-products currently stored in irradiated CANDU fuel is approximately $210/kgU. Ontario Hydro has initiated a program to study the application of new separation technolgies, such as laser-based techniques and the plasma ion cyclotron resonance separation technique, to either augment and/or supplant the chemical extraction methods. The main goal is to develop new, more economical extraction methods in order to increase the magnitude of the advantages resulting from this approach to reprocessing. (author)

  20. Assessing methane oxidation under landfill covers and its contribution to the above atmospheric CO{sub 2} levels: The added value of the isotope ({delta}{sup 13}C and {delta}{sup 18}O CO{sub 2}; {delta}{sup 13}C and {delta}D CH{sub 4}) approach

    Energy Technology Data Exchange (ETDEWEB)

    Widory, D., E-mail: d.widory@brgm.fr [BRGM, 3 ave Claude Guillemin, 45000 Orleans (France); Proust, E.; Bellenfant, G. [BRGM, 3 ave Claude Guillemin, 45000 Orleans (France); Bour, O. [INERIS, Parc Technologique ALATA, 60550 Verneuil-en-Halatte (France)

    2012-09-15

    Highlights: Black-Right-Pointing-Pointer Comparison of the isotope and mass balance approaches to evaluate the level of methane oxidation within a landfill. Black-Right-Pointing-Pointer The level of methane oxidation is not homogenous under the landfill cover and is strongly correlated to the methane flux. Black-Right-Pointing-Pointer Isotope tracking of the contribution of the methane oxidation to the CO{sub 2} concentrations in the ambient air. - Abstract: We are presenting here a multi-isotope approach ({delta}{sup 13}C and {delta}{sup 18}O of CO{sub 2}; {delta}{sup 13}C and {delta}D of CH{sub 4}) to assess (i) the level(s) of methane oxidation during waste biodegradation and its migration through a landfill cover in Sonzay (France), and (ii) its contribution to the atmospheric CO{sub 2} levels above the surface. The isotope approach is compared to the more conventional mass balance approach. Results from the two techniques are comparable and show that the CH{sub 4} oxidation under the landfill cover is heterogenous, with low oxidation percentages in samples showing high biogas fluxes, which was expected in clay covers presenting fissures, through which CH{sub 4} is rapidly transported. At shallow depth, more immobile biogas pockets show a higher level of CH{sub 4} oxidation by the methanotrophic bacteria. {delta}{sup 13}C of CO{sub 2} samples taken at different heights (from below the cover up to 8 m above the ground level) were also used to identify and assess the relative contributions of its main sources both under the landfill cover and in the surrounding atmosphere.

  1. Effects of heat-treatment atmosphere on electrochemical performances of Ni-rich mixed-metal oxide (LiNi0.80Co0.15Mn0.05O2) as a cathode material for lithium ion battery

    International Nuclear Information System (INIS)

    Ni-rich mixed metal oxides (LiNi0.80Co0.15Mn0.05O2) as a high capacity cathode material for lithium ion battery are synthesized in two different heat-treatment atmospheres of air and oxygen, respectively. A cell with LiNi0.80Co0.15Mn0.05O2 heat-treated in the oxygen atmosphere shows better electrochemical performance of initial (193.7 mAh/g) and retention (185.2 mAh/g) capacities than a cell with the cathode material heat-treated in the air atmosphere (initial capacity: 185.2 mAh/g and retention capacity: 172.0 mAh/g). In order to find the reasons of the different electrochemical performance, the samples have been characterized in detail by X-ray diffraction and scanning electron microscopy. The structural differences are revealed at the nanometer scale from the experimental works of scanning transmission electron microscopy images mapped with orientation and reliability indices and electron energy loss spectroscopy. The NiO phase of the rock salt structure is considerably developed on the surfaces of the materials in the less oxidative environment of the air atmosphere; this is related to the poor electrochemical performances

  2. Total Nitrogen Deposition (wet+dry) from the Atmosphere

    Data.gov (United States)

    U.S. Environmental Protection Agency — Oxides of Nitrogen are emitted primarily as by-products of combustion. Sources include power plants, industrial boilers, and automobiles. In addition, agricultural...

  3. Antioxidant properties of extracts from buckwheat by-products

    Directory of Open Access Journals (Sweden)

    Marzanna Hęś

    2012-06-01

    Full Text Available Background. In the course of production of buckwheat groats by-products are produced, such as bran and hull, which apart from high content of dietary fi ber, may also constitute valuable sources of antioxidants. The aim of these investigations was to determine the antioxidant activity of extracts from by-products produced during processing of buckwheat for groats. Material and method. Analyses were conducted on bran and hull of buckwheat cv. Kora. Extraction was run using acetone, methanol and water at room temperature for 24 h. The level of phenolics was determined spectrophotometrically with the Folin-Ciocalteau reagent, using (+ catechin as a standard. Antioxidant activity of extracts was analysed in relation to linoleic acid, running incubation for 19 h, by scavenging of stable radicals of DPPH (2,2-diphenyl-1-picrylhydrazyl and on the basis of metal chelating ability. Recorded results were compared with the activity of BHT (butylated hydroxytoluene. Results. The highest content of polyphenols was found in the methanol extract of hull (168.5 mg/g d.m., which was also characterised by the best antiradical properties. The lowest content of total phenols was found for water extracts of bran after grinding and fi nal bran, at 20.3 mg/g d.m. and 10.2 mg/g d.m. In the emulsion system the highest activity was found for methanol extracts of hull and bran after grinding (Wo = 0.89, as well as the extract of fi nal bran (Wo = 0.85. A higher chelating ability in relation to Fe (II ions was observed for bran extracts (after grinding – 76.1%, fi nal bran – 62.2% than for hull extracts (26%. Conclusions. Extracts obtained from by-products of buckwheat were characterised by high antioxidant activity in the applied model systems.

  4. Atmospheric chemistry in volcanic plumes.

    Science.gov (United States)

    von Glasow, Roland

    2010-04-13

    Recent field observations have shown that the atmospheric plumes of quiescently degassing volcanoes are chemically very active, pointing to the role of chemical cycles involving halogen species and heterogeneous reactions on aerosol particles that have previously been unexplored for this type of volcanic plumes. Key features of these measurements can be reproduced by numerical models such as the one employed in this study. The model shows sustained high levels of reactive bromine in the plume, leading to extensive ozone destruction, that, depending on plume dispersal, can be maintained for several days. The very high concentrations of sulfur dioxide in the volcanic plume reduces the lifetime of the OH radical drastically, so that it is virtually absent in the volcanic plume. This would imply an increased lifetime of methane in volcanic plumes, unless reactive chlorine chemistry in the plume is strong enough to offset the lack of OH chemistry. A further effect of bromine chemistry in addition to ozone destruction shown by the model studies presented here, is the oxidation of mercury. This relates to mercury that has been coemitted with bromine from the volcano but also to background atmospheric mercury. The rapid oxidation of mercury implies a drastically reduced atmospheric lifetime of mercury so that the contribution of volcanic mercury to the atmospheric background might be less than previously thought. However, the implications, especially health and environmental effects due to deposition, might be substantial and warrant further studies, especially field measurements to test this hypothesis.

  5. Utilization of Biodiesel By-Products for Biogas Production

    Directory of Open Access Journals (Sweden)

    Nina Kolesárová

    2011-01-01

    Full Text Available This contribution reviews the possibility of using the by-products from biodiesel production as substrates for anaerobic digestion and production of biogas. The process of biodiesel production is predominantly carried out by catalyzed transesterification. Besides desired methylesters, this reaction provides also few other products, including crude glycerol, oil-pressed cakes, and washing water. Crude glycerol or g-phase is heavier separate liquid phase, composed mainly by glycerol. A couple of studies have demonstrated the possibility of biogas production, using g-phase as a single substrate, and it has also shown a great potential as a cosubstrate by anaerobic treatment of different types of organic waste or energy crops. Oil cakes or oil meals are solid residues obtained after oil extraction from the seeds. Another possible by-product is the washing water from raw biodiesel purification, which is an oily and soapy liquid. All of these materials have been suggested as feasible substrates for anaerobic degradation, although some issues and inhibitory factors have to be considered.

  6. Reducing the formation of disinfection by-products by pre-ozonation.

    Science.gov (United States)

    Chang, Cheng-Nan; Ma, Ying-Shih; Zing, Fang-Fong

    2002-01-01

    The objective of this study is to apply the pre-ozonation process to reduce the formation of disinfection by-products (DBPs). The raw water sample, collected from the Te-Chi Reservoir in central Taiwan, has been polluted by fertilizer. Three types of resins were used to isolate the natural organic matter into seven types of organic fractions. The pre-ozonation was used to oxidize each organic fraction to study the reduction of DBPs of each fraction. Experimental results indicated that the pre-ozonation could reduce the concentration of dissolved organic carbon resulting in the reduction of DBP formation. With the pre-ozonation, 9-54% of DOC and more than 40% of DBPs were reduced. With the analysis of UV adsorption and Fourier transform infrared spectrometer (FTIR), the reduction of A254 and unsaturated functional groups such as aromatic ring and C=C bond containing in the water sample is the major reaction mechanism.

  7. Prospects for enhancing carbon sequestration and reclamation of degraded lands with fossil-fuel combustion by-products

    International Nuclear Information System (INIS)

    Concern for the potential global change consequences of increasing atmospheric CO2 has prompted interest in the development of mechanisms to reduce or stabilize atmospheric CO2. During the next several decades, a program focused on terrestrial sequestration processes could make a significant contribution to abating CO2 increases. The reclamation of degraded lands, such as mine-spoil sites, highway rights-of-way, and poorly managed lands, represents an opportunity to couple C sequestration with the use of fossil-fuel and energy by-products and other waste material, such as biosolids and organic wastes from human and animal sewage treatment facilities, to improve soil quality. Degraded lands are often characterized by acidic pH, low levels of key nutrients, poor soil structure, and limited moisture-retention capacity. Much is known about the methods to improve these soils, but the cost of implementation is often a limiting factor. However, the additional financial and environmental benefits of C sequestration may change the economics of land reclamation activities. The addition of energy-related by-products can address the adverse conditions of these degraded lands through a variety of mechanisms, such as enhancing plant growth and capturing of organic C in long-lived soil C pools. This review examines the use of fossil-fuel combustion by-products and organic amendments to enhance C sequestration and identifies the key gaps in information that still must be addressed before these methods can be implemented on an environmentally meaningful scale. (author)

  8. The alkaline comet assay used in evaluation of genotoxic damage of drinking water disinfection by-products (bromoform and chloroform

    Directory of Open Access Journals (Sweden)

    Messaouda Khallef

    2015-06-01

    Full Text Available The alkaline comet assay (pH 12.3 is a useful method for monitoring genotoxic effects of environmental pollutants in the root nuclei of Allium cepa and various plants; it allows the detection of single- and double-strand breaks, incomplete excision-repair sites and cross-links. It has been introduced to detect even small changes in DNA structure. It is a technically simple, highly sensitive, fast and economic test which detects in vitro and in vivo genotoxicity (DNA integrity and packing mode in any cell types examined, and requires just a few cells for its execution (Liman et al., 2011; Yıldız et al., 2009. Chloroform and bromoform are the most important trihalomethanes found in drinking water. Different concentrations of bromoform (25, 50, 75and 100µg/ml and chloroform (25, 50, 100 and 200 µg/ml were introduced to onion tuber roots. Distilled water was used as a negative control and methyl methansulfonate (MMS-10 µg/ml as positive control. All obtained data were subjected to statistical analyses by using SPSS 15.0 for Windows software. For comparison purposes, Duncan multiple range tests using one-way analysis of variance (ANOVA were employed and p<0.05 was accepted as the test of significance. Comet assay results showed that DNA damage was significant at p <0.05 for the different concentrations of chloroform and bromoform compared to the negative control which has a damage rate equal to 3.5 ± 0.7 and the positive control which has damage rate equal to 13.5 ± 2.12. The exposure of root tip cells to these disinfection by-products increases DNA damage. All concentrations examined in this study of bromoform and chloroform cause significant harm, which could be due to DNA damage induced by oxidative stress. The measurement of DNA damage in the nuclei of higher plant tissues is a new area of study with SCGE. This assay could be incorporated into in situ monitoring of atmosphere, water and soil: the comet assay allows a fast detection without

  9. The role of phytoplankton as pre-cursors for disinfection by-product formation upon chlorination.

    Science.gov (United States)

    Tomlinson, Adam; Drikas, Mary; Brookes, Justin D

    2016-10-01

    Water quality remains one of the greatest concerns with regards to human health. Advances in science and technology have resulted in highly efficient water treatment plants, significantly reducing diseases related to waterborne pathogenic microorganisms. While disinfection is critical to mitigate pathogen risk to humans, the reactions between the disinfectant and dissolved organic compounds can lead to the formation of chemical contaminants called disinfection by-products (DBPs). DBPs have been related to numerous health issues including birth defects and cancer. The formation of disinfection by-products occurs due to the reaction of oxidants and natural organic matter. DBP precursors are derived from anthropogenic sources including pharmaceuticals and chemical waste, the breakdown of vegetation from external catchment sources (allochthonous) and internally derived sources including phytoplankton (autochthonous). Current literature focuses on the contribution of allochthonous sources towards the formation of DBPs, however, the recalcitrant nature of hydrophilic phytoplankton derived organic matter indicates that autochthonous derived organic carbon can significantly contribute to total DBP concentrations. The contribution of phytoplankton to the formation of DBPs is also influenced by cellular exudation rates, chemical composition, environmental conditions and the physical and chemical conditions of the solution upon disinfection. Formation of DBPs is further influenced by the presence of cyanobacteria phyla due to their notoriety for forming dense blooms. Management of DBP formation can potentially be improved by reducing cyanobacteria as well as DBP precursors derived from other phytoplankton. PMID:27348195

  10. Atmospheric oxygenation three billion years ago

    DEFF Research Database (Denmark)

    Crowe, Sean; Døssing, Lasse Nørbye; Beukes, Nicolas J.;

    2013-01-01

    It is widely assumedthat atmospheric oxygen concentrations remained persistently low (less than 1025 timespresent levels) for about the first 2 billion years of Earth’s history1. The first long-term oxygenation of the atmosphere is thought tohave taken place around2.3 billion years ago, during...... the GreatOxidation Event2,3.Geochemical indications of transient atmospheric oxygenation, however, date back to 2.6–2.7 billion years ago4–6. Here we examine the distribution of chromium isotopes and redox-sensitive metals in the approximately 3-billionyear- old Nsuze palaeosol and in the near......-contemporaneous Ijzermyn iron formation fromthe Pongola Supergroup, South Africa.We find extensivemobilization of redox-sensitive elements through oxidative weathering. Furthermore, using our data we compute a best minimumestimate for atmospheric oxygen concentrations at that time of 331024 times present levels...

  11. Kinetic and mechanistic studies on the atmospheric oxidation of oxygenated Volatile Organic Compounds: aldehyde, ketones and esters (solvents or car emissions); Etudes des cinetiques et mecanismes de degradation atmospherique de composes organiques volatils oxygenes: aldehydes, cetones et esters (emissions automobiles et solvants)

    Energy Technology Data Exchange (ETDEWEB)

    Thevenet, R.

    2000-12-01

    The atmospheric fate of oxygenated Volatile Organic Compounds (VOCs), used as solvents or emitted by fuel car combustion, is reported in this thesis. Four saturated aldehydes (propanal, isobutyr-aldehyde, pivalaldehyde and valeraldehyde), two unsaturated aldehydes (acrolein and croton-aldehyde), three ketones (2-butanone, 2-methyl-4-pentanone, 2,4-dimethyl-3-pentanone) and three esters (methyl acrylate, methyl methacrylate and methyl pyruvate) have been studied. The rate coefficients of the OH reactions with the VOCs have been measured over the temperature range 233-372 K, using the Pulsed Laser Photolysis - Laser Induced Fluorescence (PLP-LIF) technique. The photo-reactor have been used to measure the reaction rate constants of these VOCs with Cl or O{sub 3} by the relative method. The obtained results are the first determinations for the most of the VOCs. In a second part, the atmospheric oxidation of the VOCs, initiated by OH, have been studied in smog chambers. Analysis have been performed by IRTF and GC-MS. Photo-reactors have been used, a laboratory photo-reactor in Orleans (160 L) and the European Photo-reactor EUPHORE (200 m{sup 3} with sunlight irradiation). The main oxidation pathways of the VOCs and the main products have been identified. For most of the VOCs, there are the first studies. These experimental results leaded to discuss the atmospheric fate of the VOCs in terms of lifetimes and oxidation products of the VOCs. The tropospheric ozone forming potential of the VOCs and their role in the photo-oxidant pollution have been evaluated. (author)

  12. Chlorine dioxine DBPs (disinfection by-products in drinking water

    Directory of Open Access Journals (Sweden)

    C. Lasagna

    2013-01-01

    Full Text Available Since the 1970s it has been well known that, though water for human consumption is generally disinfected before being distributed along the network, the use of chemicals results in the formation of many different Disinfection By-Products (DBPs. In the case of chlorine dioxide, the most important and represented DBPs are chlorite and chlorate: after an introduction concerning the current Italian regulation on this subject, in the experimental part the results of a 7-year minitoring campaign, concerning water of different origin collected from taps in various Italian regions, are shown. The analytical technique used for the determination of chlorite and chlorate was Ion Chromatography. The result obtained are finally discussed.

  13. Effect of Celebrity Endorsement in Advertising Activities by Product Type

    Directory of Open Access Journals (Sweden)

    Karasiewicz Grzegorz

    2014-12-01

    Full Text Available This article seeks to answer two related questions: are celebrity endorsements more likely to be result in a higher evaluation of the product being advertised than use of an anonymous individual (e.g. a typical consumer; and, if present, do these positive effects vary by product category? To answer these two questions research was conducted on a 237 student sample employing a quasi-experiment consisting of four groups (two product categories and two types of endorsers using data collected through an online survey. The results indicate that celebrity endorsements do have a positive impact on the evaluation of durable goods, but do not affect the evaluation of frequently purchased products. This finding largely confirms the assumptions of the match-up model, the meaning transfer model, and the ELM model.

  14. Antioxidant activity, cytotoxic activity and metabolic profiling of juices obtained from saffron (Crocus sativus L.) floral by-products.

    Science.gov (United States)

    Tuberoso, Carlo I G; Rosa, Antonella; Montoro, Paola; Fenu, Maurizio Antonio; Pizza, Cosimo

    2016-05-15

    Juices obtained from cold-pressed saffron (Crocus sativus L.) floral by-products were evaluated as a potential source of compounds with antioxidant and cytotoxic activities. Floral by-products were split in two batches for extraction 24 and 48h after flower harvesting, respectively. The in vitro anti-oxidant activity of these extracts was tested using the FRAP and DPPH assays, and two biological models of lipid oxidation (activity in preventing cholesterol degradation and protection against Cu(2+)-mediated degradation of the liposomal unsaturated fatty acids). The cytotoxic activity was evaluated using the MTT assay. The results show that extracts obtained 48h post-harvest contained higher levels of total polar phenols and had the highest antioxidant activity in all of the performed assays. The LC-DAD and LC-ESI-(HR)MS(n) metabolic profiles showed high levels of kaempferol derivatives and anthocyanins. This study suggests that juices from saffron floral by-products could potentially be used to develop new products for the food and health industry. PMID:26775939

  15. Antioxidant activity, cytotoxic activity and metabolic profiling of juices obtained from saffron (Crocus sativus L.) floral by-products.

    Science.gov (United States)

    Tuberoso, Carlo I G; Rosa, Antonella; Montoro, Paola; Fenu, Maurizio Antonio; Pizza, Cosimo

    2016-05-15

    Juices obtained from cold-pressed saffron (Crocus sativus L.) floral by-products were evaluated as a potential source of compounds with antioxidant and cytotoxic activities. Floral by-products were split in two batches for extraction 24 and 48h after flower harvesting, respectively. The in vitro anti-oxidant activity of these extracts was tested using the FRAP and DPPH assays, and two biological models of lipid oxidation (activity in preventing cholesterol degradation and protection against Cu(2+)-mediated degradation of the liposomal unsaturated fatty acids). The cytotoxic activity was evaluated using the MTT assay. The results show that extracts obtained 48h post-harvest contained higher levels of total polar phenols and had the highest antioxidant activity in all of the performed assays. The LC-DAD and LC-ESI-(HR)MS(n) metabolic profiles showed high levels of kaempferol derivatives and anthocyanins. This study suggests that juices from saffron floral by-products could potentially be used to develop new products for the food and health industry.

  16. Minimization of the formation of disinfection by-products.

    Science.gov (United States)

    Badawy, Mohamed I; Gad-Allah, Tarek A; Ali, Mohamed E M; Yoon, Yeoman

    2012-09-01

    The drinking water industry is required to minimize DBPs levels while ensuring adequate disinfection. In this study, efficient and appropriate treatment scheme for the reduction of disinfection by-product (DBPs) formation in drinking water containing natural organic matter has been established. This was carried out by the investigation of different treatment schemes consisting of enhanced coagulation, sedimentation, disinfection by using chlorine dioxide/ozone, filtration by sand filter, or granular activated carbon (GAC). Bench scale treatment schemes were applied on actual samples from different selected sites to identify the best conditions for the treatment of water. Samples were collected from effluent of each step in the treatment train in order to analyze pH, UV absorbance at 254 nm (UVA(254)), specific UV absorbance at 254 nm (SUVA(254)), dissolved organic carbon (DOC), haloacetic acids (HAAs) and trihalomethanes (THMs). The obtained results indicated that using pre-ozonation/enhanced coagulation/activated carbon filtration treatment train appears to be the most effective method for reducing DBPs precursors in drinking water treatment.

  17. QEMSCAN for characterisation of coal and utilisation by-products

    Energy Technology Data Exchange (ETDEWEB)

    David French; Colin Ward; Alan Butcher [University of New South Wales (Australia). CSIRO Energy Technology

    2008-05-15

    QEMSCAN is an automated electron beam image analysis technique, originally developed by CSIRO, Division of Minerals and now by a CSIRO spin-off company Intellection Pty. Ltd., which has been widely applied in the minerals industry. The objective of this project was to develop new QEMSCAN analytical techniques for coal and coal by-product characterisation that will provide unique phase-specific information that can be used by the coal industry to address technical and marketing issues, to optimise existing utilisation technologies and assist in the development of new technologies. Case studies illustrating how QEMSCAN analysis could be employed were carried out in four areas of coal production and utilisation namely - Coal preparation PF combustion; Boiler deposits; Fly and bottom ash fluidized bed combustion; and Gasification. These case studies have demonstrated that QEMSCAN analysis can provide unique information not readily obtainable by other means. In particular, data can be obtained on particle size and shape, phase identification and abundance, mode of occurrence and association of the identified phases. QEMSCAN analysis can supply information on variations in chemistry of the amorphous phase which is relevant to issues such as ash deposition in pf boilers and ash behaviour in fluidised bed systems. However, it is not an analytical panacea and should always be used in conjunction with other techniques.

  18. Health impact of disinfection by-products in swimming pools.

    Science.gov (United States)

    Villanueva, Cristina M; Font-Ribera, Laia

    2012-01-01

    This article is focused on the epidemiological evidence on the health impacts related to disinfection by-products (DBPs) in swimming pools, which is a chemical hazard generated as an undesired consequence to reduce the microbial pathogens. Specific DBPs are carcinogenic, fetotoxic and/or irritant to the airways according to experimental studies. Epidemiological evidence shows that swimming in pools during pregnancy is not associated with an increased risk of reproductive outcomes. An epidemiological study suggested an increased risk of bladder cancer with swimming pool attendance, although evidence is inconclusive. A higher prevalence of respiratory symptoms including asthma is found among swimming pool workers and elite swimmers, although the causality of this association is unclear. The body of evidence in children indicates that asthma is not increased by swimming pool attendance. Overall, the available knowledge suggests that the health benefits of swimming outweigh the potential health risks of chemical contamination. However, the positive effects of swimming should be enhanced by minimising potential risks. PMID:23247135

  19. UTILIZATION OF LOW NOx COAL COMBUSTION BY-PRODUCTS

    Energy Technology Data Exchange (ETDEWEB)

    J.Y. Hwang; X. Huang; M.G. McKimpson; R.E. Tieder; A.M. Hein; J.M. Gillis; D.C. Popko; K.L. Paxton; Z. Li; X. Liu; X. Song; R.I. Kramer

    1998-12-01

    Low NO{sub x} combustion practices are critical for reducing NO{sub x} emissions from power plants. These low NO{sub x} combustion practices, however, generate high residual carbon contents in the fly ash produced. These high carbon contents threaten utilization of this combustion by-product. This research has successfully developed a separation technology to render fly ash into useful, quality-controlled materials. This technology offers great flexibility and has been shown to be applicable to all of the fly ashes tested (more than 10). The separated materials can be utilized in traditional fly ash applications, such as cement and concrete, as well as in nontraditional applications such as plastic fillers, metal matrix composites, refractories, and carbon adsorbents. Technologies to use beneficiated fly ash in these applications are being successfully developed. In the future, we will continue to refine the separation and utilization technologies to expand the utilization of fly ash. The disposal of more than 31 million tons of fly ash per year is an important environmental issue. With continued development, it will be possible to increase economic, energy and environmental benefits by re-directing more of this fly ash into useful materials.

  20. Health impact of disinfection by-products in swimming pools

    Directory of Open Access Journals (Sweden)

    Cristina M. Villanueva

    2012-12-01

    Full Text Available This article is focused on the epidemiological evidence on the health impacts related to disinfection by-products (DBPs in swimming pools, which is a chemical hazard generated as an undesired consequence to reduce the microbial pathogens. Specific DBPs are carcinogenic, fetotoxic and/or irritant to the airways according to experimental studies. Epidemiological evidence shows that swimming in pools during pregnancy is not associated with an increased risk of reproductive outcomes. An epidemiological study suggested an increased risk of bladder cancer with swimming pool attendance, although evidence is inconclusive. A higher prevalence of respiratory symptoms including asthma is found among swimming pool workers and elite swimmers, although the causality of this association is unclear. The body of evidence in children indicates that asthma is not increased by swimming pool attendance. Overall, the available knowledge suggests that the health benefits of swimming outweigh the potential health risks of chemical contamination. However, the positive effects of swimming should be enhanced by minimising potential risks.

  1. Sampling from stochastic reservoir models constrained by production data

    Energy Technology Data Exchange (ETDEWEB)

    Hegstad, Bjoern Kaare

    1997-12-31

    When a petroleum reservoir is evaluated, it is important to forecast future production of oil and gas and to assess forecast uncertainty. This is done by defining a stochastic model for the reservoir characteristics, generating realizations from this model and applying a fluid flow simulator to the realizations. The reservoir characteristics define the geometry of the reservoir, initial saturation, petrophysical properties etc. This thesis discusses how to generate realizations constrained by production data, that is to say, the realizations should reproduce the observed production history of the petroleum reservoir within the uncertainty of these data. The topics discussed are: (1) Theoretical framework, (2) History matching, forecasting and forecasting uncertainty, (3) A three-dimensional test case, (4) Modelling transmissibility multipliers by Markov random fields, (5) Up scaling, (6) The link between model parameters, well observations and production history in a simple test case, (7) Sampling the posterior using optimization in a hierarchical model, (8) A comparison of Rejection Sampling and Metropolis-Hastings algorithm, (9) Stochastic simulation and conditioning by annealing in reservoir description, and (10) Uncertainty assessment in history matching and forecasting. 139 refs., 85 figs., 1 tab.

  2. Atmospheric Laboratory for Applications and Science Payload

    Science.gov (United States)

    1994-01-01

    This is an STS-66 mission onboard photo of the Space Shuttle Orbiter Atlantis showing the payload of the third Atmospheric Laboratory for Applications and Science (ATLAS-3) mission. During the ATLAS missions, international teams of scientists representing many disciplines combined their expertise to seek answers to complex questions about the atmospheric and solar conditions that sustain life on Earth. The ATLAS program specifically investigated how Earth's middle and upper atmospheres and climate are affected by by the sun and by products of industrial and agricultural activities on Earth. Thirteen ATLAS instruments supported experiments in atmospheric sciences, solar physics, space plasma physics, and astronomy. The instruments were mounted on two Spacelab pallets in the Space Shuttle payload bay. The ATLAS-3 mission continued a variety of atmospheric and solar studies to improve understanding of the Earth's atmosphere and its energy input from the sun. A key scientific objective was to refine existing data on variations in the fragile ozone layer of the atmosphere. The Orbiter Atlantis was launched on November 3, 1994 for the ATLAS-3 mission (STS-66).

  3. DEVELOPMENT OF ACTIVATED CARBONS FROM COAL COMBUSTION BY-PRODUCTS

    Energy Technology Data Exchange (ETDEWEB)

    Harold H. Schobert; M. Mercedes Maroto-Valer; Zhe Lu

    2003-09-30

    The increasing role of coal as a source of energy in the 21st century will demand environmental and cost-effective strategies for the use of coal combustion by-products (CCBPs), mainly unburned carbon in fly ash. Unburned carbon is nowadays regarded as a waste product and its fate is mainly disposal, due to the present lack of efficient routes for its utilization. However, unburned carbon is a potential precursor for the production of adsorbent carbons, since it has gone through a devolatilization process while in the combustor, and therefore, only requires to be activated. Accordingly, the principal objective of this work was to characterize and utilize the unburned carbon in fly ash for the production of activated carbons. The unburned carbon samples were collected from different combustion systems, including pulverized utility boilers, a utility cyclone, a stoker, and a fluidized bed combustor. LOI (loss-on-ignition), proximate, ultimate, and petrographic analyses were conducted, and the surface areas of the samples were characterized by N2 adsorption isotherms at 77K. The LOIs of the unburned carbon samples varied between 21.79-84.52%. The proximate analyses showed that all the samples had very low moisture contents (0.17 to 3.39 wt %), while the volatile matter contents varied between 0.45 to 24.82 wt%. The elemental analyses show that all the unburned carbon samples consist mainly of carbon with very little hydrogen, nitrogen, sulfur and oxygen In addition, the potential use of unburned carbon as precursor for activated carbon (AC) was investigated. Activated carbons with specific surface area up to 1075m{sup 2}/g were produced from the unburned carbon. The porosity of the resultant activated carbons was related to the properties of the unburned carbon feedstock and the activation conditions used. It was found that not all the unburned carbon samples are equally suited for activation, and furthermore, their potential as activated carbons precursors could be

  4. 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.

  5. 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.

  6. 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.

  7. Overview of Disinfection By-products and Associated Health Effects.

    Science.gov (United States)

    Villanueva, Cristina M; Cordier, Sylvaine; Font-Ribera, Laia; Salas, Lucas A; Levallois, Patrick

    2015-03-01

    The presence of chemical compounds formed as disinfection by-products (DBPs) is widespread in developed countries, and virtually whole populations are exposed to these chemicals through ingestion, inhalation, or dermal absorption from drinking water and swimming pools. Epidemiological evidence has shown a consistent association between long-term exposure to trihalomethanes and the risk of bladder cancer, although the causal nature of the association is not conclusive. Evidence concerning other cancer sites is insufficient or mixed. Numerous studies have evaluated reproductive implications, including sperm quality, time to pregnancy, menstrual cycle, and pregnancy outcomes such as fetal loss, fetal growth, preterm delivery, and congenital malformation. The body of evidence suggests only minor effects from high exposure during pregnancy on fetal growth indices such as small for gestational age (SGA) at birth. Populations highly exposed to swimming pools such as pool workers and professional swimmers show a higher prevalence of respiratory symptoms and asthma, respectively, although the direction of the association, and thus causality, is not clear among professional swimmers. The risk of asthma, wheezing, eczema, and other respiratory outcomes among children attending swimming pools has been the object of extensive research. Early studies suggested a positive association, while subsequent larger studies found no correlations or showed a protective association. Future research should develop methods to evaluate the effects of the DBP mixture and the interaction with personal characteristics (e.g., genetics, lifestyle), clarify the association between swimming pools and respiratory health, evaluate the occurrence of DBPs in low- and middle-income countries, and evaluate outcomes suggested by animal studies that have not been considered in epidemiological investigations. PMID:26231245

  8. Atmospheric degradation mechanism of organic sulfur compounds

    Energy Technology Data Exchange (ETDEWEB)

    Benter, T.; Arsene, C.

    2002-02-01

    In the present work a detailed product study has been performed on the OH radical initiated oxidation of dimethyl sulphide and dimethyl sulphoxide, under different conditions of temperature, partial pressure of oxygen and NO{sub x} concentration, in order to better define the degradation mechanism of the above compounds under conditions which prevail in the atmosphere. (orig.)

  9. Atmospheric oxygenation three billion years ago.

    Science.gov (United States)

    Crowe, Sean A; Døssing, Lasse N; Beukes, Nicolas J; Bau, Michael; Kruger, Stephanus J; Frei, Robert; Canfield, Donald E

    2013-09-26

    It is widely assumed that atmospheric oxygen concentrations remained persistently low (less than 10(-5) times present levels) for about the first 2 billion years of Earth's history. The first long-term oxygenation of the atmosphere is thought to have taken place around 2.3 billion years ago, during the Great Oxidation Event. Geochemical indications of transient atmospheric oxygenation, however, date back to 2.6-2.7 billion years ago. Here we examine the distribution of chromium isotopes and redox-sensitive metals in the approximately 3-billion-year-old Nsuze palaeosol and in the near-contemporaneous Ijzermyn iron formation from the Pongola Supergroup, South Africa. We find extensive mobilization of redox-sensitive elements through oxidative weathering. Furthermore, using our data we compute a best minimum estimate for atmospheric oxygen concentrations at that time of 3 × 10(-4) times present levels. Overall, our findings suggest that there were appreciable levels of atmospheric oxygen about 3 billion years ago, more than 600 million years before the Great Oxidation Event and some 300-400 million years earlier than previous indications for Earth surface oxygenation.

  10. Coal slurry solids/coal fluidized bed combustion by-product mixtures as plant growth media

    Science.gov (United States)

    Darmody, R.G.; Green, W.P.; Dreher, G.B.

    1998-01-01

    Fine-textured, pyritic waste produced by coal cleaning is stored in slurry settling ponds that eventually require reclamation. Conventionally, reclamation involves covering the dewatered coal slurry solids (CSS) with 1.3 m of soil to allow plant growth and prevent acid generation by pyrite oxidation. This study was conducted to determine the feasiblity of a less costly reclamation approach that would eliminate the soil cover and allow direct seeding of plants into amended CSS materials. Potential acidity of the CSS would be neutralized by additions of fluidized-bed combustion by-product (FBCB), an alkaline by-product of coal combustion. The experiment involved two sources of CSS and FBCB materials from Illinois. Birdsfoot trefoil (Lotus corniculatus L.), tall fescue (Festuca arundinacea Schreb.), and sweet clover (Melilotus officinalis (L.) Lam.) were seeded in the greenhouse into pots containing mixtures of the materials. CSS-1 had a high CaCO3:FeS2 ratio and needed no FBCB added to compensate for its potential acidity. CSS-2 was mixed with the FBCB materials to neutralize potential acidity (labeled Mix A and B). Initial pH was 5.6, 8.8, and 9.2 for the CSS-1, Mix A, and Mix B materials, respectively. At the end of the 70-day experiment, pH was 5.9 for all mixtures. Tall fescue and sweet clover grew well in all the treatments, but birdsfoot trefoil had poor emergence and survival. Elevated tissue levels of B, Cd, and Se were found in some plants. Salinity, low moisture holding capacity, and potentially phytotoxic B may limit the efficacy of this reclamation method.

  11. Production, modification, and consumption of atmospheric trace gases by microorganisms

    OpenAIRE

    Schlegel, Prof. Dr. H. G.

    2011-01-01

    Some trace gases are contained in the atmosphere in appreciable amounts: methane, carbon monoxide, hydrogen, nitrous oxide. The bulk of these gases is of biological origin. Hydrogen is a primary product of microbial metabolism under anaerobic conditions. However, before reaching the atmosphere, it is converted by methane bacteria to methane, by nitrate reducing bacteria to nitrogen and to nitrous oxide and by sulfate reducing bacteria to hydrogen sulfide. Carbon monoxide is produced from cert...

  12. Atmospheric composition change: Ecosystems-Atmosphere interactions

    NARCIS (Netherlands)

    Fowler, D.; Pilegaard, K.; Sutton, M.A.; Ambus, P.; Raivonen, M.; Duyzer, J.; Simpson, D.; Fagerli, H.; Fuzzi, S.; Schjoerring, J.K.; Granier, C.; Neftel, A.; Isaksen, I.S.A.; Laj, P.; Maione, M.; Monks, P.S.; Burkhardt, J.; Daemmgen, U.; Neirynck, J.; Personne, E.; Wichink Kruit, R.J.; Butterbach-Bahl, K.; Flechard, C.; Tuovinen, J.P.; Coyle, M.; Gerosa, G.; Loubet, B.; Altimir, N.; Gruenhage, L.; Ammann, C.; Cieslik, S.; Paoletti, E.; Mikkelsen, T.N.; Ro-Poulsen, H.; Cellier, P.; Cape, J.N.; Horvath, L.; Loreto, F.; Niinemets, U.; Palmer, P.I.; Rinne, J.; Misztal, P.; Nemitz, E.; Nilsson, D.; Pryor, S.; Gallagher, M.W.; Vesala, T.; Skiba, U.; Brueggemann, N.; Zechmeister-Boltenstern, S.; Williams, J.; O'Dowd, C.; Facchini, M.C.; Leeuw, de G.; Flossman, A.; Chaumerliac, N.; Erisman, J.W.

    2009-01-01

    Ecosystems and the atmosphere: This review describes the state of understanding the processes involved in the exchange of trace gases and aerosols between the earth's surface and the atmosphere. The gases covered include NO, NO2, HONO, HNO3, NH3, SO2, DMS, Biogenic VOC, O-3, CH4, N2O and particles i

  13. The evolution of the prebiotic atmosphere

    Science.gov (United States)

    Kasting, J. F.

    1984-01-01

    One-dimensional radiative-convective and photochemical models are used to estimate the vertical temperature structure and composition of the earth's prebiotic atmosphere. Greatly enhanced CO2 levels (100-1000 times present) are required to keep the mean surface temperature above freezing in the face of decreased solar luminosity during the earth's early history. Such high CO2 partial pressures would have affected the atmospheric oxidation state by facilitating the photochemical production of soluble species including H2O2 and H2CO. Oxidation of ferrous iron in the oceans by H2O2 dissolved in rainwater should have kept the atmospheric H2 mixing ratio above 0.0002, and the ground-level O2 mixing ratio below 10 to the -11th, regardless of the magnitude of the rate of volcanic release of reduced gases.

  14. Concentration of tritium in the atmosphere

    International Nuclear Information System (INIS)

    Concentration of tritium in the atmosphere was measured in Ibaraki, Japan. At first, sampled air was passed through a column of molecular sieve, and all the water vapour was removed. Hydrogen gas obtained by the electrolysis of water was added to the air, and oxidized by a Pd catalyst column, then the oxidized hydrogen was absorbed by a last column of molecular sieves. These columns of molecular sieves were dehydrated by heating at 400 deg C. The concentration range of atmospheric HTO and HT was 1-2 pCi/m3 in Ibaraki for a year. The concentration of atmospheric HTO varied depending on the content of water vapour in air. (J.P.N.)

  15. The global atmospheric budget of ethanol revisited

    Directory of Open Access Journals (Sweden)

    W. V. Kirstine

    2012-01-01

    Full Text Available Ethanol is an important biogenic volatile organic compound, which is increasingly used as a fuel for motor vehicles; therefore, an improved understanding of its atmospheric cycle is important. In this paper we use three sets of observational data, measured emissions of ethanol from living plants, measured concentrations of ethanol in the atmosphere and measured hydroxyl concentrations in the atmosphere (by methyl chloroform titration, to make two independent estimates related to the rate of cycling of ethanol through the atmosphere. In the first estimate, simple calculations give the emission rate of ethanol from living plants as 26 (range, 10–38 Tg yr−1. This contributes significantly to the total global ethanol source of 42 (range, 25–56 Tg yr−1. In the second estimate, the total losses of ethanol from the global atmosphere are 70 (range, 50–90 Tg yr−1, with about three-quarters of the ethanol removed by reaction with hydroxyl radicals in the gaseous and aqueous phases of the atmosphere, and the remainder lost through wet and dry deposition to land. These values of both the source of ethanol from living plants and the removal of atmospheric ethanol via oxidation by hydroxyl radicals (derived entirely from observations are significantly larger than those in recent literature. We suggest that a revision of the estimate of global ethanol emissions from plants to the atmosphere to a value comparable with this analysis is warranted.

  16. Identification of ozonation by-products of 4- and 5-methyl-1H-benzotriazole during the treatment of surface water to drinking water.

    Science.gov (United States)

    Müller, Alexander; Weiss, Stefan C; Beisswenger, Judith; Leukhardt, H Georg; Schulz, Wolfgang; Seitz, Wolfram; Ruck, Wolfgang K L; Weber, Walter H

    2012-03-01

    During the treatment of surface water to drinking water, ozonation is often used for disinfection and to remove organic trace substances, whereby oxidation by-products can be formed. Here we use the example of tolyltriazole to describe an approach for identifying relevant oxidation by-products in the laboratory and subsequently detecting them in an industrial-scale process. The identification process involves ozonation experiments with pure substances at laboratory level (concentration range mg L(-1)). The reaction solutions from different ozone contact times were analyzed by high performance liquid chromatography - quadrupole time-of-flight mass spectrometry (HPLC-QTOF-MS) in full scan mode. Various approaches were used to detect the oxidation by-products: (i) target searches of postulated oxidation by-products, (ii) comparisons of chromatograms (e.g., UV/VIS) of the different samples, and (iii) color-coded abundance time courses (kinetic) of all detected compounds were illustrated in a kind of a heat map. MS/MS, H/D exchange, and derivatization experiments were used for structure elucidation for the detected by-product. Due to the low contaminant concentrations (ng L(-1)-range) of contaminants in the untreated water, the conversion of results from laboratory experiments to an industrial-scale required the use of HPLC-MS/MS with sample enrichment (e.g., solid phase extraction.) In cases where reference substances were not available or oxidation by-products without clear structures were detected, reaction solutions from laboratory experiments were used to optimize the analytical method to detect ng L(-1) in the samples of the industrial processes. We exemplarily demonstrated the effectiveness of the methodology with the industrial chemicals 4- and 5-methyl-1H-benzotriazole (4- and 5-MBT) as an example. Moreover, not only did we identify several oxidation by-products in the laboratory experiments tentatively, but also detected three of the eleven reaction

  17. Growth of ˜5 cm2V-1s-1 mobility, p-type Copper(I) oxide (Cu2O) films by fast atmospheric atomic layer deposition (AALD) at 225°C and below

    Science.gov (United States)

    Muñoz-Rojas, D.; Jordan, M.; Yeoh, C.; Marin, A. T.; Kursumovic, A.; Dunlop, L. A.; Iza, D. C.; Chen, A.; Wang, H.; MacManus Driscoll, J. L.

    2012-12-01

    Phase pure, dense Cu2O thin films were grown on glass and polymer substrates at 225°C by rapid atmospheric atomic layer deposition (AALD). Carrier mobilities of 5 cm2V-1s-1 and carrier concentrations of ˜1016 cm-3 were achieved in films of thickness 50 - 120 nm, over a >10 cm2 area. Growth rates were ˜1 nm.min-1 which is two orders of magnitude faster than conventional ALD.. The high mobilities achieved using the atmospheric, low temperature method represent a significant advance for flextronics and flexible solar cells which require growth on plastic substrates.

  18. Growth of ∼5 cm2V−1s−1 mobility, p-type Copper(I oxide (Cu2O films by fast atmospheric atomic layer deposition (AALD at 225°C and below

    Directory of Open Access Journals (Sweden)

    D. Muñoz-Rojas

    2012-12-01

    Full Text Available Phase pure, dense Cu2O thin films were grown on glass and polymer substrates at 225°C by rapid atmospheric atomic layer deposition (AALD. Carrier mobilities of 5 cm2V−1s−1 and carrier concentrations of ∼1016 cm−3 were achieved in films of thickness 50 - 120 nm, over a >10 cm2 area. Growth rates were ∼1 nm·min−1 which is two orders of magnitude faster than conventional ALD.. The high mobilities achieved using the atmospheric, low temperature method represent a significant advance for flextronics and flexible solar cells which require growth on plastic substrates.

  19. Atmosphere purification of radon and radon daughter elements

    Science.gov (United States)

    Stein, L.

    1974-01-01

    A method of removing radon and radon daughter elements from an atmosphere containing these elements by passing the atmosphere through a bed of fluorinating compound whereby the radon and radon daughters are oxidized to their respective fluorides is discussed. These fluorides adhere to the fluorinating compound and are thus removed from the atmosphere which may then be recirculated. A method for recovering radon and separating radon from its daughter elements is also described. (Official Gazette)

  20. Bioanalytical and chemical evaluation of disinfection by-products in swimming pool water.

    Science.gov (United States)

    Yeh, Ruby Y L; Farré, Maria José; Stalter, Daniel; Tang, Janet Y M; Molendijk, Jeffrey; Escher, Beate I

    2014-08-01

    Pool water disinfection is vital to prevent microbial pathogens. However, potentially hazardous disinfection by-products (DBP) are formed from the reaction between disinfectants and organic/inorganic precursors. The aim of this study was to evaluate the presence of DBPs in various swimming pool types in Brisbane, Australia, including outdoor, indoor and baby pools, and the dynamics after a complete water renewal. Chemical analysis of 36 regulated and commonly found DBPs and total adsorbable organic halogens as well as in vitro bioassays targeting cytotoxicity, oxidative stress and genotoxicity were used to evaluate swimming pool water quality. Dichloroacetic acid and trichloroacetic acid dominated in the pool water samples with higher levels (up to 2600 μg/L) than the health guideline values set by the Australian Drinking Water Guidelines (100 μg/L). Chlorinated DBPs occurred at higher concentrations compared to tap water, while brominated DBPs decreased gradually with increasing pool water age. Biological effects were expressed as chloroacetic acid equivalent concentrations and compared to predicted effects from chemical analysis and biological characterisation of haloacetic acids. The quantified haloacetic acids explained 35-118% of the absorbable organic halogens but less than 4% of the observed non-specific toxicity (cytotoxicity), and less than 1% of the observed oxidative stress response and genotoxicity. While the DBP concentrations in Australian pools found in this study are not likely to cause any adverse health effect, they are higher than in other countries and could be reduced by better hygiene of pool users, such as thorough showering prior to entering the pool and avoiding urination during swimming.

  1. HPLC-UV ATMOSPHERIC-PRESSURE IONIZATION MASS-SPECTROMETRIC DETERMINATION OF THE DOPAMINE-D2 AGONIST N-0923 AND ITS MAJOR METABOLITES AFTER OXIDATIVE-METABOLISM BY RAT-LIVER, MONKEY LIVER, AND HUMAN LIVER-MICROSOMES

    NARCIS (Netherlands)

    SWART, PJ; BRONNER, GM; BRUINS, AP; ENSING, K; TEPPER, PG; DEZEEUW, RA

    1993-01-01

    An innovative custom-built atmospheric ionization source afforded an opportunity to perform on-line LC/MS analysis and to obtain identification of metabolites without need to rely on radioactive profiling. An HPLC with a UV detector coupled to a modified R 3010 triple quadrupole mass spectrometer wa

  2. Oxidative stability of fatty acid alkyl esters: a review.

    Directory of Open Access Journals (Sweden)

    Michal Angelovič

    2015-12-01

    performance. Biodiesels are more susceptible to degradation compared to fossil diesel because of the presence of unsaturated fatty acid chain in it. The mechanisms of oxidative degradation are autoxidation in presence of atmospheric oxygen; thermal or thermal-oxidative degradation from excess heat; hydrolysis in presence of moisture or water during storage and in fuel lines; and microbial contamination from contact with dust particles or water droplets containing fungi or bacteria into the fuel. The oxidation of lipids is a complex process in which unsaturated fatty acids are reacted with molecular oxygen by means of free radicals. The radicals react with lipids, and cause oxidative destruction of unsaturated, polyunsaturated fatty acids, therefore, known as lipid peroxidation. The factors such as heat, oxygen, light, and some metal ions, especially iron and copper, also play a significant role in creating oxidation. Oxidative products formed in biodiesel affect fuel storage life, contribute to deposit formation in tanks, and they may cause clogging of fuel filters and injection systems. The volatile organic acids formed as secondary by products of the oxidative degradation, may stimulate corrosion in the fuel system. Poor stability can lead to increasing acid numbers, increasing fuel viscosity, and the formation of gums and sediments. In general, antioxidants can prevent oxidation. Biodiesel, because it contains large numbers of molecules with double bonds, is much less oxidatively stable than petroleum-based diesel fuel. Oxidation stability is the important parameter to determine the storage of biodiesel for longer period of time. Biodiesel samples were evaluated according to methods on the base of kept in contact with pure oxygen at elevated temperatures and pressures. The results show that the performance antioxidants variation is observed for biodiesel. The most commonly used primary synthetic antioxidants

  3. Statistics in Atmospheric Science

    OpenAIRE

    Solow, Andrew R.

    2003-01-01

    This paper reviews the use of statistical methods in atmospheric science. The applications covered include the development, assessment and use of numerical physical models of the atmosphere and more empirical analysis unconnected to physical models.

  4. Planetary Atmospheric Electricity

    CERN Document Server

    Leblanc, F; Yair, Y; Harrison, R. G; Lebreton, J. P; Blanc, M

    2008-01-01

    This volume presents our contemporary understanding of atmospheric electricity at Earth and in other solar system atmospheres. It is written by experts in terrestrial atmospheric electricity and planetary scientists. Many of the key issues related to planetary atmospheric electricity are discussed. The physics presented in this book includes ionisation processes in planetary atmospheres, charge generation and separation, and a discussion of electromagnetic signatures of atmospheric discharges. The measurement of thunderstorms and lightning, including its effects and hazards, is highlighted by articles on ground and space based instrumentation, and new missions.Theory and modelling of planetary atmospheric electricity complete this review of the research that is undertaken in this exciting field of space science. This book is an essential research tool for space scientists and geoscientists interested in electrical effects in atmospheres and planetary systems. Graduate students and researchers who are new to t...

  5. Atmospheric Lepton Fluxes

    CERN Document Server

    Gaisser, Thomas K

    2014-01-01

    This review of atmospheric muons and neutrinos emphasizes the high energy range relevant for backgrounds to high-energy neutrinos of astrophysical origin. After a brief historical introduction, the main distinguishing features of atmospheric $\

  6. Mirador - Atmospheric Composition

    Data.gov (United States)

    National Aeronautics and Space Administration — Earth Science data access made simple. Atmospheric Composition is focused on the composition of Earth's atmosphere in relation to climate prediction, solar effects,...

  7. Our shared atmosphere

    Science.gov (United States)

    Our atmosphere is a precious and fascinating resource, providing air to breath, shielding us from harmful ultraviolet radiation (UV), and maintaining a comfortable climate. Since the industrial revolution, people have significantly altered the composition of the atmosphere throu...

  8. Evolution of Oxidative Continental Weathering

    Science.gov (United States)

    Konhauser, Kurt; Lalonde, Stefan

    2014-05-01

    The Great Oxidation Event (GOE) is currently viewed as a protracted process during which atmospheric oxygen levels increased above 10-5 times the present atmospheric level. This value is based on the loss of sulphur isotope mass independent fractionation (S-MIF) from the rock record, beginning at 2.45 Ga and disappearing by 2.32 Ga. However, a number of recent papers have pushed back the timing for oxidative continental weathering, and by extension, the onset of atmospheric oxygenation several hundreds of million years earlier despite the presence of S-MIF (e.g., Crowe et al., 2013). This apparent discrepancy can, in part, be resolved by the suggestion that recycling of older sedimentary sulphur bearing S-MIF might have led to this signal's persistence in the rock record for some time after atmospheric oxygenation (Reinhard et al., 2013). Here we suggest another possibility, that the earliest oxidative weathering reactions occurred in environments at profound redox disequilibrium with the atmosphere, such as biological soil crusts, riverbed and estuarine sediments, and lacustrine microbial mats. We calculate that the rate of O2 production via oxygenic photosynthesis in these terrestrial microbial ecosystems provides largely sufficient oxidizing potential to mobilise sulphate and a number of redox-sensitive trace metals from land to the oceans while the atmosphere itself remained anoxic with its attendant S-MIF signature. These findings reconcile geochemical signatures in the rock record for the earliest oxidative continental weathering with the history of atmospheric sulphur chemistry, and demonstrate the plausible antiquity of a terrestrial biosphere populated by cyanobacteria. Crowe, S.A., Dossing, L.N., Beukes, N.J., Bau, M., Kruger, S.J., Frei, R. & Canfield, D.E. Atmospheric oxygenation three billion years ago. Nature 501, 535-539 (2013). Reinhard, C.T., Planavsky, N.J. & Lyons, T.W. Long-term sedimentary recycling of rare sulphur isotope anomalies. Nature 497

  9. Mars Molniya Orbit Atmospheric Resource Mining

    Science.gov (United States)

    Mueller, Robert P.; Braun, Robert D.; Sibille, Laurent; Sforzo, Brandon; Gonyea, Keir; Ali, Hisham

    2016-01-01

    This NIAC (NASA Advanced Innovative Concepts) work will focus on Mars and will build on previous efforts at analyzing atmospheric mining at Earth and the outer solar system. Spacecraft systems concepts will be evaluated and traded, to assess feasibility. However the study will primarily examine the architecture and associated missions to explore the closure, constraints and critical parameters through sensitivity studies. The Mars atmosphere consists of 95.5 percent CO2 gas which can be converted to methane fuel (CH4) and Oxidizer (O2) for chemical rocket propulsion, if hydrogen is transported from electrolyzed water on the Mars surface or from Earth. By using a highly elliptical Mars Molniya style orbit, the CO2 atmosphere can be scooped, ram-compressed and stored while the spacecraft dips into the Mars atmosphere at periapsis. Successive orbits result in additional scooping of CO2 gas, which also serves to aerobrake the spacecraft, resulting in a decaying Molniya orbit.

  10. Catalysts development to base of Cu and Ni supported in ZrO{sub 2} for the H{sub 2} generation by the methanol reformed in oxidizing atmosphere;Desarrollo de catalizadores a base de Cu y Ni soportados en ZrO{sub 2} para la generacion de H{sub 2} mediante el reformado de metanol en atmosfera oxidante

    Energy Technology Data Exchange (ETDEWEB)

    Lopez C, P.; Gutierrez, A.; Gutierrez W, C.; Mendoza A, D.; Martinez, G.; Perez H, R., E-mail: raul.perez@inin.gob.m [ININ, Departamento de Tecnologia de Materiales, Carretera Mexico-Toluca s/n, Ocoyoacac 52750, Estado de Mexico (Mexico)

    2009-07-01

    The search of new alternating sources of energy is at the present time one of the primordial objectives to world level because of the global heating caused by the high emissions of CO{sub 2} at the atmosphere. In this sense the employment of H{sub 2} through the fuel cells offers a more viable alternative for the use of the energy coming from the connection H-H that can be appointed for use of mobile, industrial and homemade applications. However, to generate H{sub 2} in enough quantities is a great challenge at technological level for the necessity of to count with highly selective and efficient catalysts to low reaction temperatures as well as a source that comes from renewable resources. Under this context the methanol reformed in oxidizing atmosphere offers great ecological as energetics and industrial advantages; inside this investigation plane, the Cu seems to be one of the suitable candidates for this reaction due to its high capacity to generate H{sub 2}, besides the great potential of improvement in its physical-chemical properties when being worked in nano metric size and /or associated with other materials. On the other hand, it is known that the Ni addition improvement the catalytic properties because of a better material dispersion, what offers big possibilities of being applied in the H{sub 2} generation in situ by means of the methanol reformed reaction in oxidizing atmosphere; and that the conformation of bimetallic particles Cu/Ni presented high selectivity and catalytic activity for the reaction in question. (Author)

  11. Roadmap for Interdisciplinary Research on Drinking Water Disinfection By-Products

    Science.gov (United States)

    Slide presentation on interdisciplinary research on drinking water disinfection by-products which summarized important issues with drinking water disinfection by-products and focused on emerging, unregulated DBPs.

  12. Atmospheric refraction : a history

    NARCIS (Netherlands)

    Lehn, WH; van der Werf, S

    2005-01-01

    We trace the history of atmospheric refraction from the ancient Greeks up to the time of Kepler. The concept that the atmosphere could refract light entered Western science in the second century B.C. Ptolemy, 300 years later, produced the first clearly defined atmospheric model, containing air of un

  13. The epidemiology and possible mechanisms of disinfection by-products in drinking water.

    Science.gov (United States)

    Nieuwenhuijsen, Mark J; Grellier, James; Smith, Rachel; Iszatt, Nina; Bennett, James; Best, Nicky; Toledano, Mireille

    2009-10-13

    This paper summarizes the epidemiological evidence for adverse health effects associated with disinfection by-products (DBPs) in drinking water and describes the potential mechanism of action. There appears to be good epidemiological evidence for a relationship between exposure to DBPs, as measured by trihalomethanes (THMs), in drinking water and bladder cancer, but the evidence for other cancers including colorectal cancer is inconclusive and inconsistent. There appears to be some evidence for an association between exposure to DBPs, specifically THMs, and little for gestational age/intrauterine growth retardation and, to a lesser extent, pre-term delivery, but evidence for relationships with other outcomes such as low birth weight, stillbirth, congenital anomalies and semen quality is inconclusive and inconsistent. Major limitations in exposure assessment, small sample sizes and potential biases may account for the inconclusive and inconsistent results in epidemiological studies. Moreover, most studies have focused on total THMs as the exposure metric, whereas other DBPs appear to be more toxic than the THMs, albeit generally occurring at lower levels in the water. The mechanisms through which DBPs may cause adverse health effects including cancer and adverse reproductive effects have not been well investigated. Several mechanisms have been suggested, including genotoxicity, oxidative stress, disruption of folate metabolism, disruption of the synthesis and/or secretion of placental syncytiotrophoblast-derived chorionic gonadotropin and lowering of testosterone levels, but further work is required in this area.

  14. Novel technological strategies to enhance tropical thiol precursors in winemaking by-products.

    Science.gov (United States)

    Román Villegas, Tomás; Tonidandel, Loris; Fedrizzi, Bruno; Larcher, Roberto; Nicolini, Giorgio

    2016-09-15

    Grape pomace is a winemaking by-product that can be used to extract oenological tannins. Recently, some grape skin tannins were shown to contain very high amounts of two polyfunctional thiol precursors (3-S-glutathionylhexan-1-ol, 3-S-cysteinylhexan-1-ol) whose free forms are responsible for appreciated tropical-like flavours. This study shows that an oxidative treatment (no SO2) of white grape pomace and the presence of grape leaves and stems can increase the content of the above mentioned precursors. Moreover, it shows significant differences between Sauvignon Blanc, Gewuerztraminer and Mueller-Thurgau grape pomace for the 3-mercaptohexan-1-ol precursors and 4-S-cysteinyl-4-methylpentan-2-one. The grape cultivar is crucial, but the technological ability of enhancing the level of the volatile thiol precursors simply by treating the grape marc in different ways is a promising and powerful tool for the production of potentially flavouring tannins intended for food and beverage industry. PMID:27080874

  15. In situ detection of lipid peroxidation by-products in chronic liver diseases.

    Science.gov (United States)

    Paradis, V; Kollinger, M; Fabre, M; Holstege, A; Poynard, T; Bedossa, P

    1997-07-01

    Lipid peroxidation is an autocatalytic mechanism leading to oxidative destruction of cellular membranes. The deleterious consequences of this mechanism are related in part to the formation of reactive aldehydic products that bind to intra- or extracellular molecules to form adducts. Specific antibodies directed against malondialdehyde (MDA) and 4-hydroxynonenal (HNE) adducts, major aldehydic metabolites of lipid peroxidation, allowed us to investigate in situ, with an immunohistochemical procedure, the occurrence of lipid peroxidation in a panel of different chronic liver diseases. Intracellular HNE and MDA adducts were detected respectively in 24 of 39 cases (62%) and in 12 of 34 cases investigated (35%). They were localized mainly in the cytoplasm of hepatocytes, with the strongest staining observed in hemochromatosis, Wilson's disease, and in areas of acute alcoholic hepatitis in cases of alcoholic liver diseases. A peculiar pattern of immunostaining was observed in primary biliary cirrhosis where biliary cells of destroyed but also intact bile ducts strongly expressed HNE adducts. The liver extracellular matrix also displayed MDA adducts (30 of 34 cases, 88%) and HNE adducts (23 of 39 cases, 59%). While HNE adducts were specifically localized on large bundles of collagen fibers, MDA adducts were detected in a thin reticular network and in sinusoidal cells around portal tracts or fibrous septa. In conclusion, lipid peroxidation by-products are detectable in chronic liver diseases. Immunohistochemical results suggest that this mechanism is implicated very early in the pathogenesis of some of these diseases.

  16. Nonisothermal Pluto atmosphere models

    International Nuclear Information System (INIS)

    The present thermal profile calculation for a Pluto atmosphere model characterized by a high number fraction of CH4 molecules encompasses atmospheric heating by solar UV flux absorption and conductive transport cooling to the surface of Pluto. The stellar occultation curve predicted for an atmosphere of several-microbar surface pressures (which entail the existence of a substantial temperature gradient close to the surface) agrees with observations and implies that the normal and tangential optical depth of the atmosphere is almost negligible. The minimum period for atmospheric methane depletion is calculated to be 30 years. 29 refs

  17. Autotrophic ammonia oxidation by soil thaumarchaea

    OpenAIRE

    Zhang, Li-Mei; Offre, Pierre R.; He, Ji-Zheng; Verhamme, Daniel T.; Nicol, Graeme W.; Prosser, James I.

    2010-01-01

    Nitrification plays a central role in the global nitrogen cycle and is responsible for significant losses of nitrogen fertilizer, atmospheric pollution by the greenhouse gas nitrous oxide, and nitrate pollution of groundwaters. Ammonia oxidation, the first step in nitrification, was thought to be performed by autotrophic bacteria until the recent discovery of archaeal ammonia oxidizers. Autotrophic archaeal ammonia oxidizers have been cultivated from marine and thermal spring environments, bu...

  18. Alternative pathway for atmospheric particles growth.

    Science.gov (United States)

    Monge, Maria Eugenia; Rosenørn, Thomas; Favez, Olivier; Müller, Markus; Adler, Gabriela; Abo Riziq, Ali; Rudich, Yinon; Herrmann, Hartmut; George, Christian; D'Anna, Barbara

    2012-05-01

    Credible climate change predictions require reliable fundamental scientific knowledge of the underlying processes. Despite extensive observational data accumulated to date, atmospheric aerosols still pose key uncertainties in the understanding of Earth's radiative balance due to direct interaction with radiation and because they modify clouds' properties. Specifically, major gaps exist in the understanding of the physicochemical pathways that lead to aerosol growth in the atmosphere and to changes in their properties while in the atmosphere. Traditionally, the driving forces for particle growth are attributed to condensation of low vapor pressure species following atmospheric oxidation of volatile compounds by gaseous oxidants. The current study presents experimental evidence of an unaccounted-for new photoinduced pathway for particle growth. We show that heterogeneous reactions activated by light can lead to fast uptake of noncondensable Volatile Organic Compounds (VOCs) at the surface of particles when only traces of a photosensitizer are present in the seed aerosol. Under such conditions, size and mass increase; changes in the chemical composition of the aerosol are also observed upon exposure to volatile organic compounds such as terpenes and near-UV irradiation. Experimentally determined growth rate values match field observations, suggesting that this photochemical process can provide a new, unaccounted-for pathway for atmospheric particle growth and should be considered by models.

  19. Chemistry of Planetary Atmospheres: Insights and Prospects

    Science.gov (United States)

    Yung, Yuk

    2015-11-01

    Using observations from the Mariners, Pioneers, Vikings, Voyagers, Pioneer Venus, Galileo, Venus Express, Curiosity, Cassini, New Horizons, and numerous observatories both in orbit of Earth and on the ground, I will give a survey of the major chemical processes that control the composition of planetary atmospheres. For the first time since the beginning of the space age, we understand the chemistry of planetary atmospheres ranging from the primitive atmospheres of the giant planets to the highly evolved atmospheres of terrestrial planets and small bodies. Our understanding can be distilled into three important ideas: (1) The stability of planetary atmospheres against escape of their constituents to space, (2) the role of equilibrium chemistry in determining the partitioning of chemical species, and (3) the role of disequilibrium chemistry, which produces drastic departures from equilibrium chemistry. To these three ideas we must also add a fourth: the role of biochemistry at Earth's surface, which makes its atmospheric chemistry unique in the cosmochemical environment. Only in the Earth's atmosphere do strong reducing and oxidizing species coexist to such a degree. For example, nitrogen species in the Earth's atmosphere span eight oxidation states from ammonia to nitric acid. Much of the Earth's atmospheric chemistry consists of reactions initiated by the degradation of biologically produced molecules. Life uses solar energy to drive chemical reactions that would otherwise not occur; it represents a kind of photochemistry that is special to Earth, at least within the Solar System. It remains to be seen how many worlds like Earth there are beyond the Solar System, especially as we are now exploring the exoplanets using Kepler, TESS, HST, Spitzer, soon to be launched missions such as JWST and WFIRST, and ground-based telescopes. The atmospheres of the Solar System provide a benchmark for studying exoplanets, which in turn serve to test and extend our current

  20. Fluctuations in Precambrian atmospheric oxygenation recorded by chromium isotopes

    Science.gov (United States)

    Frei, Robert; Gaucher, Claudio; Poulton, Simon W.; Canfield, Don E.

    2009-09-01

    Geochemical data suggest that oxygenation of the Earth's atmosphere occurred in two broad steps. The first rise in atmospheric oxygen is thought to have occurred between ~2.45 and 2.2Gyr ago, leading to a significant increase in atmospheric oxygen concentrations and concomitant oxygenation of the shallow surface ocean. The second increase in atmospheric oxygen appears to have taken place in distinct stages during the late Neoproterozoic era (~800-542Myr ago), ultimately leading to oxygenation of the deep ocean ~580Myr ago, but details of the evolution of atmospheric oxygenation remain uncertain. Here we use chromium (Cr) stable isotopes from banded iron formations (BIFs) to track the presence of Cr(VI) in Precambrian oceans, providing a time-resolved picture of the oxygenation history of the Earth's atmosphere-hydrosphere system. The geochemical behaviour of Cr is highly sensitive to the redox state of the surface environment because oxidative weathering processes produce the oxidized hexavalent [Cr(VI)] form. Oxidation of reduced trivalent [Cr(III)] chromium on land is accompanied by an isotopic fractionation, leading to enrichment of the mobile hexavalent form in the heavier isotope. Our fractionated Cr isotope data indicate the accumulation of Cr(VI) in ocean surface waters ~2.8 to 2.6Gyr ago and a likely transient elevation in atmospheric and surface ocean oxygenation before the first great rise of oxygen 2.45-2.2Gyr ago (the Great Oxidation Event). In ~1.88-Gyr-old BIFs we find that Cr isotopes are not fractionated, indicating a decline in atmospheric oxygen. Our findings suggest that the Great Oxidation Event did not lead to a unidirectional stepwise increase in atmospheric oxygen. In the late Neoproterozoic, we observe strong positive fractionations in Cr isotopes (δ53Cr up to +4.9‰), providing independent support for increased surface oxygenation at that time, which may have stimulated rapid evolution of macroscopic multicellular life.

  1. Pluto's atmosphere near perihelion

    International Nuclear Information System (INIS)

    A recent stellar occultation has confirmed predictions that Pluto has an atmosphere which is sufficiently thick to uniformly envelope the planet and to extend far above the surface. Pluto's atmosphere consists of methane and perhaps other volatile gases at temperatures below their freezing points; it should regulate the surface temperature of its volatile ices to a globally uniform value. As Pluto approaches and passes through perihelion, a seasonal maximum in the atmospheric bulk and a corresponding minimum in the exposed volatile ice abundance is expected to occur. The lag in maximum atmospheric bulk relative to perihelion will be diagnostic of the surface thermal properties. An estimate of Pluto's atmospheric bulk may result if a global darkening (resulting from the disappearance of the seasonally deposited frosts) occurs before the time of maximum atmospheric bulk. The ice deposited shortly after perihelion may be diagnostic of the composition of Pluto's volatile reservoir

  2. Measurement of the Atmospheric $\

    CERN Document Server

    Aartsen, M G; Abdou, Y; Ackermann, M; Adams, J; Aguilar, J A; Ahlers, M; Altmann, D; Andeen, K; Auffenberg, J; Bai, X; Baker, M; Barwick, S W; Baum, V; Bay, R; Beattie, K; Beatty, J J; Bechet, S; Tjus, J Becker; Becker, K -H; Bell, M; Benabderrahmane, M L; BenZvi, S; Berdermann, J; Berghaus, P; Berley, D; Bernardini, E; Bertrand, D; Besson, D Z; Bindig, D; Bissok, M; Blaufuss, E; Blumenthal, J; Boersma, D J; Bohaichuk, S; Bohm, C; Bose1, D; Boser, S; Botner, O; Brayeur, L; Brown, A M; Bruijn, R; Brunner, J; Buitink, S; Carson, M; Casey, J; Casier, M; Chirkin, D; Christy, B; Clark, K; Clevermann, F; Cohen, S; Cowen, D F; Silva, A H Cruz; Danninger, M; Daughhetee, J; Davis, J C; De Clercq, C; De Ridder, S; Descamps, F; Desiati, P; de Vries-Uiterweerd, G; DeYoung, T; Diaz-Velez, J C; Dreyer, J; Dumm, J P; Dunkman, M; Eagan, R; Eberhardt, B; Eisch, J; Ellsworth, R W; Engdegard, O; Euler, S; Evenson, P A; Fadiran, O; Fazely, A R; Fedynitch, A; Feintzeig, J; Feusels, T; Filimonov, K; Finley, C; Fischer-Wasels, T; Flis, S; Franckowiak, A; Franke, R; Frantzen, K; Fuchs, T; Gaisser, T K; Gallagher, J; Gerhardt, L; Gladstone, L; Glusenkamp, T; Goldschmidt, A; Golup, G; Goodman, J A; Gora, D; Grant, D; Gross, A; Grullon, S; Gurtner, M; Ha, C; Ismail, A Haj; Hallgren, A; Halzen, F; Hanson, K; Heereman, D; Heimann, P; Heinen, D; Helbing, K; Hellauer, R; Hickford, S; Hill, G C; Hoffman, K D; Hoffmann, R; Homeier, A; Hoshina, K; Huelsnitz, W; Hulth, P O; Hultqvist, K; Hussain, S; Ishihara, A; Jacobi, E; Jacobsen, J; Japaridze, G S; Jlelati, O; Kappes, A; Karg, T; Karle, A; Kiryluk, J; Kislat, F; Klas, J; Klein, S R; Kohne, J -H; Kohnen, G; Kolanoski, H; Kopke, L; Kopper, C; Kopper, S; Koskinen, D J; Kowalski, M; Krasberg, M; Kroll, G; Kunnen, J; Kurahashi, N; Kuwabara, T; Labare, M; Landsman, H; Larson, M J; Lauer, R; Lesiak-Bzdak, M; Lunemann, J; Madsen, J; Maruyama, R; Mase, K; Matis, H S; McNally, F; Meagher, K; Merck, M; Meszaros, P; Meures, T; Miarecki, S; Middell, E; Milke, N; Miller, J; Mohrmann, L; Montaruli, T; Morse, R; Nahnhauer, R; Naumann, U; Nowicki, S C; Nygren, D R; Obertacke, A; Odrowski, S; Olivas, A; Olivo, M; O'Murchadha, A; Panknin, S; Paul, L; Pepper, J A; Heros, C Perez de los; Pieloth, D; Pirk, N; Posselt, J; Price, P B; Przybylski, G T; Radel, L; Rawlins, K; Redl, P; Resconi, E; Rhode, W; Ribordy, M; Richman, M; Riedel, B; Rodrigues, J P; Rott, C; Ruhe, T; Ruzybayev, B; Ryckbosch, D; Saba, S M; Salameh, T; Sander, H -G; Santander, M; Sarkar, S; Schatto, K; Scheel, M; Scheriau, F; Schmidt, T; Schmitz, M; Schoenen, S; Schoneberg, S; Schonherr, L; Schonwald, A; Schukraft, A; Schulte, L; Schulz, O; Seckel, D; Seo, S H; Sestayo, Y; Seunarine, S; Sheremata, C; Smith, M W E; Soiron, M; Soldin, D; Spiczak, G M; Spiering, C; Stamatikos, M; Stanev, T; Stasik, A; Stezelberger, T; Stokstad, R G; Stoss, A; Strahler, E A; Strom, R; Sullivan, G W; Taavola, H; Taboada, I; Tamburro, A; Ter-Antonyan, S; Tilav, S; Toale, P A; Toscano, S; Usner, M; van der Drift, D; van Eijndhoven, N; Van Overloop, A; van Santen, J; Vehring, M; Voge1, M; Vraeghe, M; Walck, C; Waldenmaier, T; Wallraff, M; Walter, M; Wasserman, R; Weaver, Ch; Wendt, C; Westerhoff, S; Whitehorn, N; Wiebe, K; Wiebusch, C H; Williams, D R; Wissing, H; Wolf, M; Wood, T R; Woschnagg, K; Xu, C; Xu, D L; Xu, X W; Yanez, J P; Yodh, G; Yoshida, S; Zarzhitsky, P; Ziemann, J; Zierke, S; Zilles, A; Zoll, M

    2012-01-01

    We report the first observation in a high energy neutrino telescope of cascades induced by atmospheric electron neutrinos and by neutral current interactions of atmospheric neutrinos of all flavors. Using data recorded during the first year of operation of IceCube's DeepCore low energy extension, a sample of 1029 events is observed in 281 days of data. The number of observed cascades is $N_{\\rm cascade} = 496 \\pm 66 (stat.) \\pm 88(syst.)$ and the rest of the sample consists of residual backgrounds due to atmospheric muons and charged current interactions of atmospheric muon neutrinos. The flux of the atmospheric electron neutrinos is determined in the energy range between approximately 80 GeV and 6 TeV and is consistent with models of atmospheric neutrinos.

  3. Atmospheric Circulation of Exoplanets

    CERN Document Server

    Showman, Adam P; Menou, Kristen

    2009-01-01

    We survey the basic principles of atmospheric dynamics relevant to explaining existing and future observations of exoplanets, both gas giant and terrestrial. Given the paucity of data on exoplanet atmospheres, our approach is to emphasize fundamental principles and insights gained from Solar-System studies that are likely to be generalizable to exoplanets. We begin by presenting the hierarchy of basic equations used in atmospheric dynamics, including the Navier-Stokes, primitive, shallow-water, and two-dimensional nondivergent models. We then survey key concepts in atmospheric dynamics, including the importance of planetary rotation, the concept of balance, and scaling arguments to show how turbulent interactions generally produce large-scale east-west banding on rotating planets. We next turn to issues specific to giant planets, including their expected interior and atmospheric thermal structures, the implications for their wind patterns, and mechanisms to pump their east-west jets. Hot Jupiter atmospheric d...

  4. Quality and safety of oils and fats obtained as co-products or by-products of the food chain and destined to animal production

    OpenAIRE

    Pignoli, Giovanni

    2008-01-01

    The aim of the first part of this thesis was to evaluate the effect of trans fatty acid- (TFA), contaminant, polycyclic aromatic hydrocarbon (PAH)- and oxidation productenriched diets on the content of TFA and conjugated linoleic acid (CLA) isomers in meat and liver of both poultry and rabbit. The enriched feedings were prepared with preselected fatty co-and by-products that contained low and high levels of TFA (low, palm fatty acid distillate; high, hydrogenated palm fatty aci...

  5. Chlorinated and nitrogenous disinfection by-product formation from ozonation and post-chlorination of natural organic matter surrogates.

    Science.gov (United States)

    Bond, Tom; Templeton, Michael R; Rifai, Omar; Ali, Hussain; Graham, Nigel J D

    2014-09-01

    Ozonation before chlorination is associated with enhanced formation of chloropicrin, a halonitromethane disinfection by-product (DBP), during drinking water treatment. In order to elucidate reasons for this, five natural organic matter (NOM) surrogates were treated using both chlorination and ozonation-chlorination under controlled laboratory conditions. Selected surrogates comprised two phenolic compounds, two free amino acids and one dipeptide; these were resorcinol, 3-aminophenol, L-aspartic acid, β-alanine and ala-ala, respectively. Quantified DBPs included chloropicrin, chloroform, dichloroacetonitrile and trichloroacetonitrile. Relative to chlorination alone, increases in the formation of chloropicrin from ozonation-chlorination varied from 138% for 3-aminophenol to 3740% for ala-ala for the four amine surrogates. This indicates that ozone is more effective than chlorine in mediating a rate-limiting oxidation step in chloropicrin formation, most plausibly involving conversion of an amine group to a nitro group. While both hydrophilic and hydrophobic surrogates acted as chloropicrin precursors, ala-ala was the most reactive precursor following ozonation-chlorination. Since peptides are far commoner in drinking water sources than free amino acids, further research into chemical oxidation of these species by ozone and chlorine is recommended. In contrast, oxidation with ozone prior to chlorination reduced chloroform formation moderately for the two phenolic compounds.

  6. Worldwide trend of atmospheric mercury since 1995

    Directory of Open Access Journals (Sweden)

    F. Slemr

    2011-01-01

    Full Text Available Concern about the adverse effects of mercury on human health and ecosystems has led to tightening emission controls since the mid 1980s. But the resulting mercury emissions reductions in many parts of the world are believed to be offset or even surpassed by the increasing emissions in rapidly industrializing countries. Consequently, concentrations of atmospheric mercury are expected to remain roughly constant. Here we show that the worldwide atmospheric mercury concentration have decreased by about 20 to 38% since 1996 as indicated by long term monitoring at stations in the Southern and Northern Hemispheres combined with intermittent measurements of latitudinal distribution over the Atlantic Ocean. The total reduction of the atmospheric mercury burden of this magnitude within 14 yrs is unprecedented among most of atmospheric trace gases and is at odds with the current mercury emission inventories with nearly constant emissions over the period. It suggests a major shift in the biogeochemical cycle of mercury including oceans and soil reservoirs. Decreasing reemissions from the legacy of historical mercury emissions are the most likely explanation for this decline since the hypothesis of an accelerated oxidation rate of elemental mercury in the atmosphere is not supported by the observed trends of other trace gases. Consequently, models of the atmospheric mercury cycle have to include soil and ocean mercury pools and their dynamics to be able to make projections of future trends.

  7. Dry matter yields of maize grown with coal combustion by-products

    International Nuclear Information System (INIS)

    Major coal combustion by-products (CCBPs) include fly ash, bottom ash, flue gas desulfurization (scrubber sludge) and fluidized bed combustion residues, and coal gasification ashes. Interest in using these products on agricultural land as soil amendments has recently arisen. However, the impact of these products on soils properties and plant growth are unknown. The new technologies in coal power plants are designed to reduce sulfur (S) emissions into the air. Flue Gas Desulfurization (FGD) (scrubber sludge) and Fluidized Bed Combustion (FBC) residues are CCBPs from this new technology. Both of these types of products have received only limited attention relative to agricultural use (Carlson and Adriano, 1992). The FGD products normally result from the addition of limestone slurries to flue gas streams to control sulfur emissions. The final product generally consists of fly ash and Ca-S (sometimes some Mg-S) salts containing different proportions of sulfite/sulfate/carbonate (Santhanam et al., 1979; Miller, 1987). Compositions of products vary extensively dependent on factors such as type of coal used, combustion conditions, and types of devices used for emission control. These products often contain high soluble salts and may contain enhanced amounts of heavy metals. In a few products, much of the sulfite is converted to sulfate and the resulting products contain high CaSO4, (gypsum hydrite). The FBC products normally result from mixing coal and limestone in the furnace in a fluidized bed created by the injection of air. This usually results in an alkaline final product, relatively high in Ca salts (sulfite/sulfate/oxide) with variable amounts of ash whose composition depends on the type of coal and specific boiler systems used (Terman et al., 1978; Korcak, 1980a, 1982). 20 refs., 3 figs

  8. The Atmospheric Fate of Organic Nitrogen Compounds

    Science.gov (United States)

    Borduas, Nadine

    Organic nitrogen compounds are present in our atmosphere from biogenic and anthropogenic sources and have impacts on air quality and climate. Due to recent advances in instrumentation, these compounds are being detected in the gas and particle phases, raising questions as to their source, processing and sinks in the environment. With their recently identified role as contributors to aerosol formation and growth, their novel large scale use as solvents in carbon capture and storage (CCS) technology and their emissions from cigarette smoke, it is now important to address the gaps in our understanding of the fate of organic nitrogen. Experimentally and theoretically, I studied the chemical atmospheric fate of specific organic nitrogen compounds in the amine, amide and isocyanate families, yielding information that can be used in chemical transport models to assess the fate of this emerging class of atmospheric molecules. I performed kinetic laboratory studies in a smog chamber to measure the room temperature rate coefficient for reaction with the hydroxyl radical of monoethanolamine, nicotine, and five different amides. I employed online-mass spectrometry techniques to quantify the oxidation products. I found that amines react quickly with OH radicals with lifetimes of a few hours under sunlit conditions, producing amides as oxidation products. My studies on amides revealed that they have much longer lifetimes in the atmosphere, ranging from a few hours to a week. Photo-oxidation of amides produces isocyanates and I investigated these mechanisms in detail using ab initio calculations. Furthermore, I experimentally measured isocyanic acid's Henry's Law constant as well as its hydrolysis rate constants to better understand its sinks in the atmosphere. Finally, I re-examined the structure-activity relationship (SAR) of organic nitrogen molecules for improved model parameterizations.

  9. The Atmosphere and Climate of Venus

    Science.gov (United States)

    Bullock, M. A.; Grinspoon, D. H.

    this chapter in terms of the initial forcing due to a perturbation, radiative response, and indirect responses, which are feedbacks — either positive or negative. When applied to one Venus climate model, we found that the albedo-radiative feedback is more important than greenhouse forcing for small changes in atmospheric H2O and SO2. An increase in these gases cools the planet by making the clouds brighter. On geologic timescales the reaction of some atmospheric species (SO2, CO, OCS, S, H2O, H2S, HCl, HF) with surface minerals could cause significant changes in atmospheric composition. Laboratory data and thermochemical modeling have been important for showing that atmospheric SO2 would be depleted in ~10 m.y. if carbonates are available at the surface. Without replenishment, the clouds would disappear. Alternatively, the oxidation of pyrite could add SO2 to the atmosphere while producing stable Fe oxides at the surface. The correlation of near-infrared high emissivity (dark) surface features with three young, large volcanos on Venus is strong evidence for recent volcanic activity at these sites, certainly over the timescale necessary to support the clouds. We address the nature of heterogeneous reactions with the surface and the implications for climate change on Venus. Chemical and mineralogical signatures of past climates must exist at the surface and below, so in situ experiments on the composition of surface layers are vital for reconstructing Venus' past climate. Many of the most Earth-like planets found around other stars will probably resemble Venus or a younger version of Venus. We finish the chapter with discussing what Venus can tell us about life in the universe, since it is an example of a planetary climate rendered uninhabitable. It also resembles our world's likely future. As with the climate history of Venus, however, the timing of predictable climate transitions on the Earth is poorly constrained by the data.

  10. Designing Dynamic Atmospheres

    DEFF Research Database (Denmark)

    Højlund, Marie; Kinch, Sofie

    2012-01-01

    This paper addresses the notion of atmospheres from a designerly perspective, and discusses temporal challenges facing interaction designers when acknowledging the dynamic character of it. As atmospheres are created in the relation between body, space, and time, a pragmatic approach seems useful...

  11. Proterozoic atmospheric oxygen

    DEFF Research Database (Denmark)

    Canfield, Donald Eugene

    2014-01-01

    This article is concerned with the evolution of atmospheric oxygen concentrations through the Proterozoic Eon. In particular, this article will seek to place the history of atmospheric oxygenation through the Proterozoic Eon in the context of the evolving physical environment including the history...

  12. Update on Atmospheric Neutrinos

    CERN Document Server

    González-Garciá, M Concepción; Peres, O L G; Stanev, T; Valle, José W F

    1998-01-01

    We discuss the impact of recent experimental results on the determination of atmospheric neutrino oscillation parameters. We use all published results on atmospheric neutrinos, including the preliminary large statistics data of Super-Kamiokande. We re-analyze the data in terms of both $\

  13. High surface area, electrically conductive nanocarbon-supported metal oxide

    Energy Technology Data Exchange (ETDEWEB)

    Worsley, Marcus A.; Han, Thomas Yong-Jin; Kuntz, Joshua D.; Cervantes, Octavio; Gash, Alexander E.; Baumann, Theodore F.; Satcher, Jr., Joe H.

    2015-07-14

    A metal oxide-carbon composite includes a carbon aerogel with an oxide overcoat. The metal oxide-carbon composite is made by providing a carbon aerogel, immersing the carbon aerogel in a metal oxide sol under a vacuum, raising the carbon aerogel with the metal oxide sol to atmospheric pressure, curing the carbon aerogel with the metal oxide sol at room temperature, and drying the carbon aerogel with the metal oxide sol to produce the metal oxide-carbon composite. The step of providing a carbon aerogel can provide an activated carbon aerogel or provide a carbon aerogel with carbon nanotubes that make the carbon aerogel mechanically robust.

  14. MAVEN Imaging UV Spectrograph Results on the Mars Atmosphere and Atmospheric Escape

    Science.gov (United States)

    Chaffin, Michael; Schneider, Nick; McClintock, Bill; Stewart, Ian; Deighan, Justin; Jain, Sonal; Clarke, John; Holsclaw, Greg; Montmessin, Franck; Lefevre, Franck; Chaufray, Jean-Yves; Stiepen, Arnaud; Crismani, Matteo; Mayyasi, Majd; Evans, Scott; Stevens, Mike; Yelle, Roger; Jakosky, Bruce

    2016-04-01

    The Imaging Ultraviolet Spectrograph (IUVS) is one of nine science instruments aboard the Mars Atmosphere and Volatile and EvolutioN (MAVEN) spacecraft, whose payload is dedicated to exploring the upper atmosphere of Mars and understanding the magnitude and drivers of Mars' atmospheric escape rate. IUVS uses ultraviolet light to investigate the lower and upper atmosphere and ionosphere of Mars. The instrument is among the most powerful spectrographs sent to another planet, with several key capabilities: (1) separate Far-UV & Mid-UV channels for stray light control, (2) a high resolution echelle mode to resolve deuterium and hydrogen emission, (3) internal instrument pointing and scanning capabilities to allow complete mapping and nearly continuous operation, and (4) optimization for airglow studies. IUVS, along with other MAVEN instruments, obtains a comprehensive picture of the current state of the Mars upper atmosphere and ionosphere and the processes that control atmospheric escape. We present an overview of selected IUVS results, including (1) the discovery of diffuse aurora at Mars, and its contrast with previously detected discrete aurora localized near crustal magnetic fields; (2) widespread detection of mesospheric clouds; (3) Significant seasonal and short-timescale variability in thermospheric composition; (4) Global ozone maps spanning six months of seasonal evolution; and (5) mapping of the Mars H and O coronas, deriving the escape rates of H and O and their variability. This last is of particular importance for understanding the long term evolution of Mars and its atmosphere, with the observed preset escape of H potentially capable of removing a large fraction of Mars' initial water inventory, and the differential escape of O relative to H potentially providing a net source of oxidizing power to the atmosphere and planet at present, in contrast with a photochemical theory that predicts stoichiometrically balanced escape. The atmospheric and escape

  15. Thermodynamic properties of cerium oxide

    International Nuclear Information System (INIS)

    Thermodynamic properties of cerium oxides in the CeO2-CeO1.5 composition range are studied. For this purpose method of electromotive force with solid electrolyte is used, equilibrium constants of reduction of cerium oxides by hydrogen are measured. Necessity of using atmosphere of argon or purified nitrogen to work with pyrophoric cerium oxides is stressed. The obtained results and the earlier known literary data on CeO2 and Ce2O3 thermodynamic properties are tabulated. 14 refs.; 5 tabs

  16. In situ ruminal crude protein degradability of by-products from cereals, oilseeds and animal origin

    NARCIS (Netherlands)

    Habib, G.; Khan, N.A.; Ali, M.; Bezabih, M.

    2013-01-01

    The aim of this study was to establish a database on in situ ruminal crude protein (CP) degradability characteristics of by-products from cereal grains, oilseeds and animal origin commonly fed to ruminants in Pakistan and South Asian Countries. The oilseed by-products were soybean meal, sunflower me

  17. By-Product Formation in Repetitive PCR Amplification of DNA Libraries during SELEX

    DEFF Research Database (Denmark)

    Tolle, Fabian; Wilke, Julian; Wengel, Jesper;

    2014-01-01

    -recognizing aptamers. Little is known about the formation of such by-products when employing nucleic acid libraries as templates. We report on the formation of two different forms of by-products, named ladder- and non-ladder-type observed during repetitive amplification in the course of in vitro selection experiments...

  18. Acid mine drainage treatment using by-products from quicklime manufacturing as neutralization chemicals.

    Science.gov (United States)

    Tolonen, Emma-Tuulia; Sarpola, Arja; Hu, Tao; Rämö, Jaakko; Lassi, Ulla

    2014-12-01

    The aim of this research was to investigate whether by-products from quicklime manufacturing could be used instead of commercial quicklime (CaO) or hydrated lime (Ca(OH)2), which are traditionally used as neutralization chemicals in acid mine drainage treatment. Four by-products were studied and the results were compared with quicklime and hydrated lime. The studied by-products were partly burnt lime stored outdoors, partly burnt lime stored in a silo, kiln dust and a mixture of partly burnt lime stored outdoors and dolomite. Present application options for these by-products are limited and they are largely considered waste. Chemical precipitation experiments were performed with the jar test. All the studied by-products removed over 99% of Al, As, Cd, Co, Cu, Fe, Mn, Ni, Zn and approximately 60% of sulphate from acid mine drainage. However, the neutralization capacity of the by-products and thus the amount of by-product needed as well as the amount of sludge produced varied. The results indicated that two out of the four studied by-products could be used as an alternative to quicklime or hydrated lime for acid mine drainage treatment. PMID:25193795

  19. Nutritional diversity of agricultural and agro-industrial by-products for ruminant feeding

    Directory of Open Access Journals (Sweden)

    J.A.G. Azevêdo

    2012-10-01

    Full Text Available Fifty-seven by-products were collected from regions throughout Brazil. Chemical composition, in vitro neutral detergent fiber digestibility (IVNDFD, and total digestible nutrients (TDN were determined with the objective of grouping by-products with similar nutritional characteristics. The by-products belonging to group one (G1 presented the highest content of neutral detergent fiber exclusive of ash and nitrogenous compounds [aNDFom(n] and lowest energy content, with 42.5% and 38.8% of IVNDFD and TDN, respectively. A new cluster analysis was carried in order to better characterize G2 by-products, six subgroups (SGs were established (SG1 to SG6. SG1 by-products had the highest and the lowest values for lignin and TDN, respectively. SG2 by-products had the highest aNDFom(n value, with TDN and IVNDFD values greater than 600 and 700g/kg, respectively, and crude protein (CP value below 200g/kg in dry matter (DM. Among all the subgroups, SG3 had the highest TDN (772g/kg and IVNDFD (934g/kg values and the lowest lignin (23g/kg in DM value. The ether extract was what most influenced the hierarchical establishment of residual grouping in SG4. SG5 by-products had the highest concentration of non-fibrous carbohydrate. Different from the other subgroups, SG6 by-products had the highest value of available CP.

  20. 40 CFR 63.302 - Standards for by-product coke oven batteries.

    Science.gov (United States)

    2010-07-01

    ... batteries. 63.302 Section 63.302 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR... National Emission Standards for Coke Oven Batteries § 63.302 Standards for by-product coke oven batteries... oven emissions from each affected existing by-product coke oven battery that exceed any of...