WorldWideScience

Sample records for atmospheric oxidation by-products

  1. Oxidants and oxidation in the Earth's atmosphere

    Science.gov (United States)

    1995-01-01

    The 1994 BOC Priestley Conference was held at Bucknell University in Lewisburg, Pennsylvania, from June 24 through June 27, 1994. This conference, managed by the American Chemical Society (ACS), was a joint celebration with the Royal Society of Chemistry (RSC) commemorating Joseph Priestley's arrival in the U.S. and his discovery of oxygen. The basic theme of the conference was 'Oxidants and Oxidation in the Earth's Atmosphere,' with a keynote lecture on the history of ozone. A distinguished group of U.S. and international atmospheric chemists addressed the issues dominating current research and policy agendas. Topics crucial to the atmospheric chemistry of global change and local and regional air pollution were discussed. The program for the conference included four technical sessions on the following topics: (1) Oxidative Fate of Atmospheric Pollutants; (2) Photochemical Smog and Ozone; (3) Stratospheric Ozone; and (4) Global Tropospheric Ozone.

  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

    2009-01-08

    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. Chlorination and chloramination of aminophenols in aqueous solution: oxidant demand and by-product formation.

    Science.gov (United States)

    Mehrez, O Abou; Dossier-Berne, F; Legube, B

    2015-01-01

    Chlorination and monochloramination of aminophenols (AP) were carried out in aqueous solution at 25°C and at pH 8.5. Oxidant demand and disinfection by-product formation were determined in excess of oxidant. Experiments have shown that chlorine consumption of AP was 40-60% higher than monochloramine consumption. Compared with monochloramination, chlorination of AP formed more chloroform and haloacetic acids (HAA). Dichloroacetic acid was the major species of HAA. Chloroform and HAA represented, respectively, only 1-8% and 14-15% of adsorbable organic halides (AOX) by monochloramination but up to 29% and 39% of AOX by chlorination.

  7. Reassessing the atmospheric oxidation mechanism of toluene

    Science.gov (United States)

    Ji, Yuemeng; Zhao, Jun; Terazono, Hajime; Misawa, Kentaro; Levitt, Nicholas P.; Li, Yixin; Lin, Yun; Peng, Jianfei; Wang, Yuan; Duan, Lian; Pan, Bowen; Zhang, Fang; Feng, Xidan; An, Taicheng; Marrero-Ortiz, Wilmarie; Secrest, Jeremiah; Zhang, Annie L.; Shibuya, Kazuhiko; Molina, Mario J.; Zhang, Renyi

    2017-08-01

    Photochemical oxidation of aromatic hydrocarbons leads to tropospheric ozone and secondary organic aerosol (SOA) formation, with profound implications for air quality, human health, and climate. Toluene is the most abundant aromatic compound under urban environments, but its detailed chemical oxidation mechanism remains uncertain. From combined laboratory experiments and quantum chemical calculations, we show a toluene oxidation mechanism that is different from the one adopted in current atmospheric models. Our experimental work indicates a larger-than-expected branching ratio for cresols, but a negligible formation of ring-opening products (e.g., methylglyoxal). Quantum chemical calculations also demonstrate that cresols are much more stable than their corresponding peroxy radicals, and, for the most favorable OH (ortho) addition, the pathway of H extraction by O2 to form the cresol proceeds with a smaller barrier than O2 addition to form the peroxy radical. Our results reveal that phenolic (rather than peroxy radical) formation represents the dominant pathway for toluene oxidation, highlighting the necessity to reassess its role in ozone and SOA formation in the atmosphere.

  8. Disinfection by-products effect on swimmers oxidative stress and respiratory damage.

    Science.gov (United States)

    Llana-Belloch, Salvador; Priego Quesada, Jose Ignacio; Pérez-Soriano, Pedro; Lucas-Cuevas, Ángel G; Salvador-Pascual, Andrea; Olaso-González, Gloria; Moliner-Martinez, Yolanda; Verdú-Andres, Jorge; Campins-Falco, Pilar; Gómez-Cabrera, M Carmen

    2016-08-01

    Disinfection by-products (DBPs) are generated through the reaction of chlorine with organic and inorganic matter in indoor swimming pools. Different DBPs are present in indoor swimming pools. This study evaluated the effects of different chlorinated formations in oxidative stress and lung damage in 20 swimmers after 40 min of aerobic swimming in 3 indoor pools with different characteristics. Biological samples were collected to measure lung damage (serum-surfactant-associated proteins A and B), oxidative stress parameters (plasma protein carbonylation and malondialdehyde, and whole-blood glutathione oxidation), and swimming exertion values (blood lactate) before and after exercise. Free chlorine and combined chlorine in water, and chlorine in air samples were determined in all the swimming pools. Chlorination as disinfection treatment led to the formation of chloramines in water samples, mainly mono- and dichloramine. However, free chlorine was the predominate species in ultraviolet-treated swimming pool. Levels of total chlorine increased as a function of the swimming activity in chlorinated swimming pools. The lower quality of the installation resulted in a higher content of total chlorine, especially in air samples, and therefore a higher exposure of the swimmer to DBPs. However, the concentration level of chlorinated DBPs did not result in significant variation in serum-surfactant-associated proteins A and oxidative stress parameters in swimmers. In conclusion, the quality of the installation affected the DBPs concentration; however, it did not lead to lung epithelial damage and oxidative stress parameters in swimmers.

  9. Improved measurements of atmospheric nitrous oxide

    Science.gov (United States)

    Wendel, JoAnna

    2014-10-01

    Nitrous oxide (N2O), one of the main greenhouse gases, is known for its degrading effect on Earth's ozone layer. The gas is created naturally by microbial activity on land and in the oceans and artificially by emissions from human-made processes, through fertilization or burning fossil fuels. As the climate continues to warm, it has become imperative to be able to track and quantify the greenhouse gas content of the atmosphere, and various satellite missions have been launched to do so.

  10. Formation of brominated disinfection by-products and bromate in cobalt catalyzed peroxymonosulfate oxidation of phenol.

    Science.gov (United States)

    Liu, Kuo; Lu, Junhe; Ji, Yuefei

    2015-11-01

    Formation of halogenated disinfection by-products (DBPs) in sulfate radical [Formula: see text] based oxidation processes attracted considerable attention recently. However, the underlying reaction pathways have not been well explored. This study focused on the transformation of Br(-) in cobalt activated peroxymonosulfate (Co(2+)/PMS) oxidation process. Phenol was added as a model compound to mimic the reactivity of natural organic matter (NOM). It was revealed that Br(-) was efficiently transformed to reactive bromine species (RBS) including free bromine and bromine radicals (Br, [Formula: see text] , etc.) in Co(2+)/PMS system. [Formula: see text] played a principal role during this process. RBS thus generated resulted in the bromination of phenol and formation brominated DBPs (Br-DBPs) including bromoform and bromoacetic acids, during which brominated phenols were detected as the intermediates. Br-DBPs were further degraded by excessive [Formula: see text] and transformed to bromate ultimately. Free bromine was also formed in the absence of Co(2+), suggesting Br(-) could be oxidized by PMS per se. Free bromine was incorporated to phenol sequentially leading to Br-DBPs as well. However, Br-DBPs could not be further transformed in the absence of [Formula: see text] . This is the first study that elucidated the comprehensive transformation map of Br(-) in PMS oxidation systems, which should be taken into consideration when PMS was applied to eliminate contamination in real practice. Copyright © 2015 Elsevier Ltd. All rights reserved.

  11. Transformation of iodide and formation of iodinated by-products in heat activated persulfate oxidation process.

    Science.gov (United States)

    Wang, Lu; Kong, Deyang; Ji, Yuefei; Lu, Junhe; Yin, Xiaoming; Zhou, Quansuo

    2017-08-01

    Formation of halogenated disinfection by-products (DBPs) in sulfate radical-based advanced oxidation processes (SR-AOPs) have attracted considerable concerns recently. Previous studies have focused on the formation of chlorinated and brominated DBPs. This research examined the transformation of I(-) in heat activated PS oxidation process. Phenol was employed as a model compound to mimic the reactivity of dissolved natural organic matter (NOM) toward halogenation. It was found that I(-) was transformed to free iodine which attacked phenol subsequently leading to iodinated DBPs such as iodoform and iodoacetic acids. Iodophenols were detected as the intermediates during the formation of the iodoform and triiodoacetic acid (TIAA). However, diiodoacetic acid (DIAA) was formed almost concomitantly with iodophenols. In addition, the yield of DIAA was significantly higher than that of TIAA, which is distinct from conventional halogenation process. Both the facts suggest that different pathway might be involved during DIAA formation in SR-AOPs. Temperature and persulfate dose were the key factors governing the transformation process. The iodinated by-products can be further degraded by excessive SO4(-) and transformed to iodate. This study elucidated the transformation pathway of I(-) in SR-AOPs, which should be taken into consideration when persulfate was applied in environmental matrices containing iodine. Copyright © 2017 Elsevier Ltd. All rights reserved.

  12. Removal of atrazine and its by-products from water using electrochemical advanced oxidation processes.

    Science.gov (United States)

    Komtchou, Simon; Dirany, Ahmad; Drogui, Patrick; Robert, Didier; Lafrance, Pierre

    2017-11-15

    Atrazine (ATZ) is one of the most common pesticides detected in surface water in Quebec (Canada). The present study was mainly focused on the degradation of ATZ and its by-products using electrochemical advanced oxidation processes such as photo-electro-Fenton (PEF), electro-Fenton (EF) and anodic-oxidation with simultaneous H2O2 formation (AO - H2O2). The comparison of these processes showed that PEF process was found to be the most effective process in removing ATZ and its by-products from both synthetic solution (ATZ0 = 100 μg L(-1)) and real agricultural surface water enriched with ATZ (ATZ0 = 10 μg L(-1)). Different operating parameters, including wavelength of the light, pH, current density and the presence of natural organic matter (humic acids) were investigated for PEF process using boron-doped diamond (BDD) anode and graphite cathode. The current density and the wavelength of the light were the most important parameters in the ATZ degradation efficiency. The best operating conditions were recorded for the synthetic samples at a current density of 18.2 mA cm(-2), a pH of 3.0 and treatment time of 45 min. Results showed that atrazine-desethyl-desisopropyl (DEDIA) was the most important by-product recorded. More than 99% of ATZ oxidation was recorded after 15 min of treatment and all the concentrations of major by-products were less than the limit of detection after 45 min of treatment. The PEF process was also tested for real surface water contaminated by ATZ: i) with and without addition of iron; ii) without pH adjustment (pH ∼ 6.7) and with pH adjustment (pH ∼ 3.1). In spite of the presence of radical scavenger and iron complexation the PEF process was more effective to remove ATZ from real surface water when the pH value was adjusted near to 3.0. The ATZ removal was 96.0% with 0.01 mM of iron (kapp = 0.13 min(-1)) and 100% with 0.1 mM of iron (kapp = 0.17 min(-1)). Copyright © 2017 Elsevier Ltd. All rights reserved.

  13. 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...

  14. 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.

  15. Grape by-product extracts against microbial proliferation and lipid oxidation: a review.

    Science.gov (United States)

    Mattos, Gabriela N; Tonon, Renata V; Furtado, Angela Al; Cabral, Lourdes Mc

    2017-03-01

    The wine industry is responsible for the production of million tons of waste, such as grape skin, stalk, sludge and seeds, which can be considered inexpensive sources of phenolic compound owing to incomplete extraction during wine production. Phenolic compounds, also called polyphenols, comprise the most abundant bioactive compounds in grape and are recognized by their antioxidant and antimicrobial potential. Because of their functional properties, extracts obtained from grape wastes, which are rich in phenolic compounds, can be employed in the development of many products, ranging from medical to food applications, decreasing the growth of spoilage and pathogenic microorganisms and inhibiting lipid oxidation. These characteristics are motivating the research for alternative sources of natural antioxidant and antimicrobial agents, aimed at decreasing the use of artificial additives, which have been associated with some toxic effects. This article provides a review of the use of grape by-product extracts and their bioactive compounds as natural antioxidant and antimicrobial agents in food products. © 2016 Society of Chemical Industry. © 2016 Society of Chemical Industry.

  16. Oxidant abundances in rainwater and the evolution of atmospheric oxygen

    Science.gov (United States)

    Kasting, J. F.; Holland, H. D.; Pinto, J. P.

    1985-01-01

    H2O2 is probably the dominant oxidant in rainwater at O2 levels lower than 0.01-0.001 present atmospheric levels (PAL), and the magnitude of its dissolved flux is sensitive to the concentration of the trace gases NO, CO, and CH4 in the atmosphere, as well as to the partial pressure of atmospheric CO2. The earlier interpretation of the paleosol data in terms of the ratio of p-O2/p-CO2 in the atmosphere must be modified by taking into account the effects of photochemically produced oxidants and reactants at p-O2 of les than 0.01 PAL.

  17. Atmospheric oxidation of hydrocarbons: Formation of hydroperoxides and peroxyacids

    Science.gov (United States)

    Hanst, Philip L.; Gay, Bruch W.

    Hydrocarbons at ppm levels in air have been oxidized in the absence of nitrogen oxides. Chlorine atoms served as initiators of the oxidations. Infrared analysis showed alkyl hydroperoxides to be formed early in the oxidation sequences. Aldehydes and ketones were also formed, followed by the appearance of peroxyacids. Peroxyacetic acid was found to be an especially stable reaction product. Laboratory rate data and recent atmospheric measurements of NO, NO 2 and HO 2 indicate that hydroperoxides and peroxyacids are also formed in the real atmosphere.

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

    Energy Technology Data Exchange (ETDEWEB)

    Ji, Yuefei [Department of Environmental Science and Engineering, Nanjing Agricultural University, Nanjing 210095 (China); Kong, Deyang [Nanjing Institute of Environmental Science, Ministry of Environmental Protection of PRC, Nanjing 210042 (China); Lu, Junhe, E-mail: jhlu@njau.edu.cn [Department of Environmental Science and Engineering, Nanjing Agricultural University, Nanjing 210095 (China); Jin, Hao; Kang, Fuxing; Yin, Xiaoming; Zhou, Quansuo [Department of Environmental Science and Engineering, Nanjing Agricultural University, Nanjing 210095 (China)

    2016-08-05

    Highlights: • Cobalt catalyzed peroxymonosulfate oxidation of tetrabromobisphenol A. • Phenolic moiety was the reactive site for sulfate radical attack. • Pathways include β-scission, oxidation, debromination and coupling reactions. • Brominated disinfection by-products were found during TBBPA degradation. • Humic acid inhibited TBBPA degradation but promoted DBPs formation. - Abstract: 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 (SO{sub 4}{sup ·−}) with TBBPA was determined to be 5.27 × 10{sup 10} M{sup −1} s{sup −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 SO{sub 4}{sup ·−}. 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 6–10 h. 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.

  19. Comparative study of oxidants and ozone in Los Angeles atmosphere

    Energy Technology Data Exchange (ETDEWEB)

    Renzetti, N.A.; Romanovsky, J.C.

    1956-01-01

    The smog in the Pasadena atmosphere was analyzed from July 15 - Nov. 15, 1955. Pasadena is an area of high incidence of smog during this particular time of year. The instruments used were a phenolphthalin oxidant apparatus, a potassium iodide continuous oxidant recorder, a rubber cracking apparatus, and an ozone ultraviolet spectrometer. The instrumentation and measuring methods are described in detail, as well as the laboratory calibrations. The results of the sampling are summarized in graphical form with comments on interferences.

  20. Trace bromide ion impurity leads to formation of chlorobromoaromatic by-products in peroxymonosulfate-based oxidation of chlorophenols.

    Science.gov (United States)

    Fang, Changling; Wang, Zhaohui; Feng, Min; Huang, Ying; Yang, Fei; Liu, Jianshe

    2017-09-01

    Trace bromide (Br(-)) released from industrial effluents or brominated compounds is able to directly react with peroxymonosulfate (PMS) to generate a series of reactive oxidants which can oxidize and also halogenate organics. We report the identification and evolution of by-products during 2,4,6-trichlorophenol (TCP) degradation in the presence of PMS and trace Br(-). The influencing factors, including Br(-) concentration and pH, were investigated. The depletion of TCP was accelerated with increasing trace Br(-) concentration (0-0.2 mM) and was affected by the initial pH (3.0-7.0). The chlorinated and brominated compounds were identified in simulated wastewater during treatment with PMS. Notably, the potential formation of chlorobromoaromatic by-products was demonstrated for the first time in the presence of PMS and trace Br(-). The possible reaction pathways of TCP and its derivatives are discussed. These findings have important implications for the future applications of PMS-based oxidation processes. Copyright © 2017 Elsevier Ltd. All rights reserved.

  1. Explosion characteristics of flammable organic vapors in nitrous oxide atmosphere.

    Science.gov (United States)

    Koshiba, Yusuke; Takigawa, Tomihisa; Matsuoka, Yusaku; Ohtani, Hideo

    2010-11-15

    Despite unexpected explosion accidents caused by nitrous oxide have occurred, few systematic studies have been reported on explosion characteristics of flammable gases in nitrous oxide atmosphere compared to those in air or oxygen. The objective of this paper is to characterize explosion properties of mixtures of n-pentane, diethyl ether, diethylamine, or n-butyraldehyde with nitrous oxide and nitrogen using three parameters: explosion limit, peak explosion pressure, and time to the peak explosion pressure. Then, similar mixtures of n-pentane, diethyl ether, diethylamine, or n-butyraldehyde with oxygen and nitrogen were prepared to compare their explosion characteristics with the mixtures containing nitrous oxide. The explosion experiments were performed in a cylindrical vessel at atmospheric pressure and room temperature. The measurements showed that explosion ranges of the mixtures containing nitrous oxide were narrow compared to those of the mixtures containing oxygen. On the other hand, the maximum explosion pressures of the mixtures containing nitrous oxide were higher than those of the mixtures containing oxygen. Moreover, our experiments revealed that these mixtures differed in equivalence ratios at which the maximum explosion pressures were observed: the pressures of the mixtures containing nitrous oxide were observed at stoichiometry; in contrast, those of the mixtures containing oxygen were found at fuel-rich area. Chemical equilibrium calculations confirmed these behaviors. Copyright © 2010 Elsevier B.V. All rights reserved.

  2. Atmospheric nitrous oxide uptake in boreal spruce forest soil

    Science.gov (United States)

    Siljanen, Henri; Welti, Nina; Heikkinen, Juha; Biasi, Christina; Martikainen, Pertti

    2017-04-01

    Nitrous oxide (N2O) uptake from the atmosphere has been found in forest soils but environmental factors controlling the uptake and its atmospheric impact are poorly known. We measured N2O fluxes over growing season in a boreal spruce forest having control plots and plots with long nitrogen fertilization history. Also methane (CH4) fluxes were measured to compare the atmospheric impact of N2O and CH4fluxes. Soil chemical and physical characteristics and climatic conditions were measured as background data. Nitrous oxide consumption and uptake mechanisms were measured in complementary laboratory incubation experiments using stable isotope approaches. Gene transcript numbers of nitrous oxide reductase (nosZ) I and II genes were quantified along the incubation with elevated N2O atmosphere. The spruce forests without fertilization history showed highest N2O uptake rates whereas pine forest had low emissions. Nitrous oxide uptake correlated positively with soil moisture, high soil silt content, and low temperature. Nitrous oxide uptake varied seasonally, being highest in spring and autumn when temperature was low and water content was high. The spruce forest was sink for CH4.Methane fluxes were decoupled from the N2O fluxes (i.e. when the N2O uptake was high the CH4 uptake was low). By using GWP approach, the cooling effect of N2O uptake was on average 30% of the cooling effect of CH4 uptake in spruce forest without fertilization. Anoxic conditions promoted higher N2O consumption rates in all soils. Gene transcription of nosZ-I genes were activated at beginning of the incubation. However, atypical/clade-II nosZ was not detected. These results suggests, that also N2O uptake rates have to be considered when accounting for the GHG budget of spruce forests.

  3. Characterizing chlorine oxidation of dissolved organic matter and disinfection by-product formation with fluorescence spectroscopy and parallel factor analysis

    Science.gov (United States)

    Beggs, Katherine M. H.; Summers, R. Scott; McKnight, Diane M.

    2009-12-01

    Relationships between chlorine demand and disinfection by-product (DBP) formation during chlorination and fluorescence of dissolved organic matter (DOM) were developed. Fluorescence excitation and emission (EEM) spectroscopy was employed, and parameters including fluorescence index, redox index, and overall fluorescence intensity (OFI) were correlated to chlorine demand and DBP formation. The EEMs were also analyzed using a well established global parallel factor analysis (PARAFAC) model which resolves the fluorescence signal into 13 components, including quinone-like and protein-like components. Over an 8-day chlorination period the OFI and sum of the 13 PARAFAC loadings decreased by more than 70%. The remaining identified quinone-like compounds within the DOM were shifted to a more oxidized state. Quinone fluorescence was strongly correlated to both reduced fluorescence intensity and to chlorine demand which indicates that fluorescence may be used to track the chlorine oxidation of DOM. Quinone fluorescence was also correlated strongly with both classes of regulated DBPs: total trihalomethanes and haloacetic acids. Quinone-like components were found to be strongly correlated to overall, short-term, and long-term specific DBP formation. The results of this study show that fluorescence is a useful tool in tracking both DOM oxidation and DBP formation during chlorination.

  4. Investigating Atmospheric Oxidation with Molecular Dynamics Imaging and Spectroscopy

    Science.gov (United States)

    Merrill, W. G.; Case, A. S.; Keutsch, F. N.

    2013-06-01

    Volatile organic compounds (VOCs) in the Earth's atmosphere constitute trace gas species emitted primarily from the biosphere, and are the subject of inquiry for a variety of air quality and climate studies. Reactions intiated (primarily) by the hydroxyl radical (OH) lead to a myriad of oxygenated species (OVOCs), which in turn are prone to further oxidation. Investigations of the role that VOC oxidation plays in tropospheric chemistry have brought to light two troubling scenarios: (1) VOCs are responsible in part for the production of two EPA-regulated pollutants---tropospheric ozone and organic aerosol---and (2) the mechanistic details of VOC oxidation remain convoluted and poorly understood. The latter issue hampers the implementation of near-explicit atmospheric simulations, and large discrepancies in OH reactivity exist between measurements and models at present. Such discrepancies underscore the need for a more thorough description of VOC oxidation. Time-of-flight measurements and ion-imaging techniques are viable options for resolving some of the mechanistic and energetic details of VOC oxidation. Molecular beam studies have the advantage of foregoing unwanted bimolecular reactions, allowing for the characterization of specific processes which must typically compete with the complex manifold of VOC oxidation pathways. The focus of this work is on the unimolecular channels of organic peroxy radical intermediates, which are necessarily generated during VOC oxidation. Such intermediates may isomerize and decompose into distinct chemical channels, enabling the unambiguous detection of each pathway. For instance, a (1 + 1') resonance enhanced multiphoton ionization (REMPI) scheme may be employed to detect carbon monoxide generated from a particular unimolecular process. A number of more subtle mechanistic details may be explored as well. By varying the mean free path of the peroxy radicals in a flow tube, the role of collisional quenching in these unimolecular

  5. 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)

  6. Composition and oxidation state of sulfur in atmospheric particulate matter

    Directory of Open Access Journals (Sweden)

    A. F. Longo

    2016-10-01

    Full Text Available The chemical and physical speciation of atmospheric sulfur was investigated in ambient aerosol samples using a combination of sulfur near-edge x-ray fluorescence spectroscopy (S-NEXFS and X-ray fluorescence (XRF microscopy. These techniques were used to determine the composition and oxidation state of sulfur in common primary emission sources and ambient particulate matter collected from the greater Atlanta area. Ambient particulate matter samples contained two oxidation states: S0 and S+VI. Ninety-five percent of the individual aerosol particles (> 1 µm analyzed contain S0. Linear combination fitting revealed that S+VI in ambient aerosol was dominated by ammonium sulfate as well as metal sulfates. The finding of metal sulfates provides further evidence for acidic reactions that solubilize metals, such as iron, during atmospheric transport. Emission sources, including biomass burning, coal fly ash, gasoline, diesel, volcanic ash, and aerosolized Atlanta soil, and the commercially available bacterium Bacillus subtilis, contained only S+VI. A commercially available Azotobacter vinelandii sample contained approximately equal proportions of S0 and S+VI. S0 in individual aerosol particles most likely originates from primary emission sources, such as aerosolized bacteria or incomplete combustion.

  7. 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.

  8. Composition and oxidation state of sulfur in atmospheric particulate matter

    Science.gov (United States)

    Longo, Amelia F.; Vine, David J.; King, Laura E.; Oakes, Michelle; Weber, Rodney J.; Huey, Lewis Gregory; Russell, Armistead G.; Ingall, Ellery D.

    2016-10-01

    The chemical and physical speciation of atmospheric sulfur was investigated in ambient aerosol samples using a combination of sulfur near-edge x-ray fluorescence spectroscopy (S-NEXFS) and X-ray fluorescence (XRF) microscopy. These techniques were used to determine the composition and oxidation state of sulfur in common primary emission sources and ambient particulate matter collected from the greater Atlanta area. Ambient particulate matter samples contained two oxidation states: S0 and S+VI. Ninety-five percent of the individual aerosol particles (> 1 µm) analyzed contain S0. Linear combination fitting revealed that S+VI in ambient aerosol was dominated by ammonium sulfate as well as metal sulfates. The finding of metal sulfates provides further evidence for acidic reactions that solubilize metals, such as iron, during atmospheric transport. Emission sources, including biomass burning, coal fly ash, gasoline, diesel, volcanic ash, and aerosolized Atlanta soil, and the commercially available bacterium Bacillus subtilis, contained only S+VI. A commercially available Azotobacter vinelandii sample contained approximately equal proportions of S0 and S+VI. S0 in individual aerosol particles most likely originates from primary emission sources, such as aerosolized bacteria or incomplete combustion.

  9. Photo-Fenton oxidation of 3-amino-5-methylisoxazole: a by-product from biological breakdown of some pharmaceutical compounds.

    Science.gov (United States)

    Souza, Bianca M; Marinho, Belisa A; Moreira, Francisca C; Dezotti, Márcia W C; Boaventura, Rui A R; Vilar, Vítor J P

    2017-03-01

    The present study aims to assess the removal of 3-amino-5-methylisoxazole (AMI), a recalcitrant by-product resulting from the biological breakdown of some pharmaceuticals, applying a solar photo-Fenton process assisted by ferrioxalate complexes (SPFF) (Fe3+/H2O2/oxalic acid/UVA-Vis) and classical solar photo-Fenton process (SPF) (Fe2+/H2O2/UVA-Vis). The oxidation ability of SPFF was evaluated at different iron/oxalate molar ratios (1:3, 1:6, and 1:9, with [total iron] = 3.58 × 10-2 mM and [oxalic acid] = 1.07 × 10-1, 2.14 × 10-1 and 3.22 × 10-1 mM, respectively) and pH values (3.5-6.5), using low iron contents (2.0 mg Fe3+ L-1). Additionally, the use of other organic ligands such as citrate and ethylenediamine-N,N'-disuccinic acid (EDDS) was tested. The oxidation power of the classical SPF was assessed at different pH values (2.8-4.0) using 2.0 mg Fe2+ per liter. Furthermore, the effect of AMI concentration (2-20 mg L-1), presence of inorganic ions (Cl-, SO42-, NO3-, HCO3-, NH4+), and radical scavengers (sodium azide and D-mannitol) on the SPF method at pH 3.5 was also assessed. Experiments were done using a lab-scale photoreactor with a compound parabolic collector (CPC) under simulated solar radiation. A pilot-scale assay was conducted using the best operation conditions. While at near neutral pH, an iron/oxalate molar ratio of 1:9 led to the removal of 72 % of AMI after 90 min of SPFF, at pH 3.5, an iron/oxalate molar ratio of 1:3 was enough to achieve complete AMI degradation (below the detection limit) after 30 min of reaction. The SPF process at pH 3.5 underwent a slower AMI degradation, reaching total AMI degradation after 40 min of reaction. The scale up of SPF process showed a good reproducibility. Oxalic and oxamic acids were identified as the main low-molecular-weight carboxylic acids detected during the pilot-scale SPF reaction. Graphical abstract ᅟ.

  10. [Low molecular weight oxidation by-products produced during catalytic ozonation with ferric hydroxide of NOM fractions isolated from filtrated water].

    Science.gov (United States)

    Lu, Jin-Feng; Qiu, Jiao; Ma, Jun; Zhang, Tao; Chen, Zhong-Lin; Wang, Huan

    2009-03-15

    Natural organic matter (NOM) in a filtered river water from a water treatment plant was isolated and fractionated into six types of fractions. The aim of the work is to investigate the formation of the low molecular weight (LMW) oxidation by-products (i.e. aldehydes, ketones and ketoacids) after ferric hydroxide-catalyzed ozonation of individual NOM fractions. Results showed that catalytic ozonation could improve the reduction of the dissolved organic matter (DOC) and specific UV absorbance (SUVA) at 254 nm compared with ozonation alone. However, catalytic ozonation with ferric hydroxide could not produce less LMW oxidation by-products than ozonation. Hydrophobic neutral (HON) produced much higher yields of the LMW oxidation by-products than other fractions both during catalytic ozonation and ozonation alone, while the basic NOM fractions formed relatively lower productions of these by-products. Like the case of ozonation alone, the predominant contributors for the yields of aldehydes and ketoacids formed in catalytic ozonation were formaldehyde and pyruvic acid, respectively. Among these NOM fractions, HON produced the highest yields of the formaldehyde and pyruvic acid after catalytic ozonation. The yield of formaldehyde from HON was up to 71.6% of the total aldehydes and ketones, and the pyruvic acid concentration of HON was 78.6 microg/mg after catalytic ozonation. In addition, NOM fractions became more biodegradable after catalytic ozonation, because the percent of total LMW by-products carbon in the final DOC after catalytic ozonation was higher than ozonation alone.

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

    Science.gov (United States)

    Baca, R.; Juárez, G.; Solache, H.; Andraca, J.; Martinez, J.; Garcia, O.; Kryshtab, T.; Peña-Sierra, R.

    2010-02-01

    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.

  12. 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.

  13. 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

  14. 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.

  15. Oxidation of Organic Compoundsin the Atmospheric Aqueous Phase: Development of a New Explicit Oxidation Mechanism

    Science.gov (United States)

    Mouchel-Vallon, C.; Bregonzio-Rozier, L.; Monod, A.; Leriche, M.; Doussin, J. F.; Chaumerliac, N. M.; Deguillaume, L.

    2014-12-01

    Current 3D models tend to underestimate the production of secondary organic aerosol (SOA) in the atmosphere (Volkamer et al., 2006). Recent studies argue that aqueous chemistry in clouds could be responsible for a significant production of SOA (Ervens et al., 2011; Carlton and Turpin, 2013) through oxidative and non-oxidative processes. Aqueous phase reactivity of organic compounds needs to be thoroughly described in models to identify organic molecules available to contribute to SOA mass. Recently, new empirical methods have been developed to allow the estimate of HO·reaction rates in the aqueous phase (Doussin and Monod, 2013, Minakata et al., 2009). These methods provide global rate constants together with branching ratios for HO·abstraction and addition on organic compounds of atmospheric interests. Current cloud chemistry mechanisms do not take the different possible pathways into account. Based on these structure-activity relationships, a new detailed aqueous phase mechanism describing the oxidation of hydrosoluble organic compounds resulting from isoprene oxidation is proposed. This new aqueous phase mechanism is coupled with the detailed gas phase mechanism MCM v3.2 (Jenkin et al., 1997; Saunders et al., 2003) through a kinetic of mass transfer parameterization for the exchange between gas phase and aqueous phase. The GROMHE SAR (Raventos-Duran et al., 2010) allows the evaluation of Henry's law constants for organic compounds. Variable photolysis in both phases using the TUV 4.5 radiative transfer model (Madronich and Flocke, 1997) is also calculated. The resulting multiphase mechanism has been implemented in a cloud chemistry model. Focusing on oxygenated compounds produced from the isoprene oxidation, sensitivity tests and comparisons with multiphase experiments performed in the framework of the CUMULUS project in the CESAM atmospheric simulation chamber (Wang et al., 2011) will be presented. Volkamer et al., GRL, 33, L17811, 2006. Carlton and Turpin

  16. Atmospheric oxidants. [ozone concentration and combustion product aspects in spacecraft design

    Science.gov (United States)

    Daniels, G. E.

    1973-01-01

    The ingredients which cause the air pollution are a mixture of oxides of organic matter (mostly nitrogen oxides and hydrocarbons) and ozone. Ozone, although considered one of the rare atmospheric gases, needs consideration in spacecraft design because of its chemical reaction (oxidation) with organic materials, especially rubber, which becomes hard and brittle under tension in a few minutes time. At the earth surface, a maximum of 60 parts per hundred million of oxidants composed of nitrogen oxides, hydrocarbons, sulphur dioxide, sulphur trioxides, peroxides, and ozone can be expected for 72 hours when smog occurs. A table representing distribution of ozone concentration with atmospheric altitude is included.

  17. Effect of oat by-product antioxidants and vitamin E on the oxidative stability of pork from pigs fed diets supplemented with linseed oil.

    Science.gov (United States)

    Sobotka, Wiesław; Flis, Marianna; Antoszkiewicz, Zofia; Lipiński, Krzysztof; Zduńczyk, Zenon

    2012-02-01

    The aim of the experiment was to compare the antioxidative potential of an oat by-product with the effect of vitamin E on the oxidative stability of pork from pigs fed a diet enriched with linseed oil. Thirty-four crossbreed barrows were fed individually from 39 to 109 kg body weight (BW) on one of four diets: a control diet based on barley-triticale-soybean (Diet C), a diet containing an oat byproduct (Diet O), and the same diets supplemented with vitamin E (100 mg/kg diet) (Diets CE and OE, respectively). The oat by-product, comprising oat hulls and bran, was included at 10 and 20% in the grower and finisher diets, respectively. To Diets O and OE, refined rapeseed oil was added to equalise their energy content to Diets C and CE. Compared to Diets C and CE, the inclusion of the oat by-product in Diets O and OE increased the antioxidative capacity of water-soluble and lipid soluble compounds in these diets. Dietary treatment did not influence growth performance, slaughter value, longissimus dorsi (LD) muscle quality measured by nutrient contents, pH, drip loss or colour. Vitamin E supplementation increased the alpha-tocopherol concentration in serum and meat (p oxidative stability of meat. However, dietary inclusion with the oat by-product was not as efficient as supplementation with vitamin E.

  18. 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

    2016-10-05

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

  19. Kinetics of a Criegee intermediate that would survive high humidity and may oxidize atmospheric SO2

    National Research Council Canada - National Science Library

    Hao-Li Huang; Wen Chao; Jim Jr-Min Lin

    2015-01-01

    Criegee intermediates are thought to play a role in atmospheric chemistry, in particular, the oxidation of SO2, which produces SO3 and subsequently H2SO4, an important constituent of aerosols and acid rain...

  20. Effect of methanol, ethylene glycol and their oxidation by-products on the activity of Pt-based oxygen-reduction catalysts

    Energy Technology Data Exchange (ETDEWEB)

    Travitsky, N.; Peled, E. [School of Chemistry, Sackler Faculty of Exact Sciences, Tel Aviv University, Ramat Aviv, Tel Aviv 69978 (Israel); Burstein, L.; Rosenberg, Y. [Wolfson Applied Materials Research Center, Tel Aviv University, Tel Aviv 69978 (Israel)

    2009-10-20

    Direct-oxidation fuel cells (DOFC) are promising electrochemical devices for various applications. In addition to methanol (MeOH), alternative fuels are being tested in a search for lower toxicity, safer handling, and higher energy density. Ethylene glycol (EG) was employed as one of such fuels. However, DOFCs face several problems, such as fuel crossover through the membrane during its operation. This not only lowers the cell potential but also poisons the catalyst for the oxygen-reduction reaction (ORR). Experiments were performed on the poisoning of Pt and Pt-alloy ORR catalysts (both commercial and homemade, by electroless deposition), by fuels and their oxidation by-products. At 25 C, methanol poisoning was found to be reversible and the catalytic activity measured afterwards in a fuel-free solution and the electrochemical surface area (ECSA) were enhanced. The effect of poisoning by methanol and ethylene glycol and their oxidation intermediates is reported here for the first time. The severity of poisoning was found to be MeOH << formaldehyde < formic acid. In solutions of EG and its oxidation by-products, the poisoning order was EG {<=} glycolic acid < oxalic acid, the poisoning of all three being more severe than that of methanol. The catalysts most resistant both to MeOH and EG poisoning were commercial acid-treated PtCo and homemade PtCoSn. The reasons for the enhanced tolerance were investigated and PtCoSn was found to be the less active both in the methanol and ethylene glycol oxidation processes. (author)

  1. 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 (pavocado 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. Copyright © 2011 Elsevier Ltd. All rights reserved.

  2. The contribution of manure and fertilizer nitrogen to atmospheric nitrous oxide since 1860

    Science.gov (United States)

    Davidson, Eric A.

    2009-09-01

    Atmospheric nitrous oxide concentrations have been increasing since the industrial revolution and currently account for 6% of total anthropogenic radiative forcing. Microbial production in soils is the dominant nitrous oxide source; this has increased with increasing use of nitrogen fertilizers. However, fertilizer use alone cannot account for the historical trends of atmospheric concentrations of nitrous oxide. Here, I analyse atmospheric concentrations, industrial sources of nitrous oxide, and fertilizer and manure production since 1860. Before 1960, agricultural expansion, including livestock production, may have caused globally significant mining of soil nitrogen, fuelling a steady increase in atmospheric nitrous oxide. After 1960, the rate of the increase rose, due to accelerating use of synthetic nitrogen fertilizers. Using a regression model, I show that 2.0% of manure nitrogen and 2.5% of fertilizer nitrogen was converted to nitrous oxide between 1860 and 2005; these percentage contributions explain the entire pattern of increasing nitrous oxide concentrations over this period. Consideration of processes that re-concentrate soil nitrogen, such as manure production by livestock, improved `hind-casting' of nitrous oxide emissions. As animal protein consumption in human diets increases globally, management of manure will be an important component of future efforts to reduce anthropogenic nitrous oxide sources.

  3. Chemical kinetics of homogeneous atmospheric oxidation of sulfur dioxide

    Science.gov (United States)

    Sander, S. P.; Seinfeld, J. H.

    1976-01-01

    A systematic evaluation of known homogeneous SO2 reactions which might be important in air pollution chemistry is carried out. A mechanism is developed to represent the chemistry of NOx/hydrocarbon/SO2 systems, and the mechanism is used to analyze available experimental data appropriate for quantitative analysis of SO2 oxidation kinetics. Detailed comparisons of observed and predicted concentration behavior are presented. In all cases, observed SO2 oxidation rates cannot be explained solely on the basis of those SO2 reactions for which rate constants have been measured. The role of ozone-olefin reactions in SO2 oxidation is elucidated.

  4. 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.

  5. 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.

  6. The atmosphere of heaven: the 1799 nitrous oxide researches reconsidered.

    Science.gov (United States)

    Jay, Mike

    2009-09-20

    Thomas Beddoes's and Humphry Davy's accounts of the nitrous oxide experiments carried out at the Pneumatic Institution in 1799 include extravagant descriptions of its mind-altering effects. Many people, both at the time and subsequently, have considered these descriptions to be the product not of the gas but of its subjects' overheated imaginations. To what extent were these effects 'all in the mind' of the experimenters? Modern understandings of nitrous oxide throw new light on this question; but it was also considered, and resolved in different ways, by Beddoes and Davy themselves.

  7. Oxidative stability of refined olive and sunflower oils supplemented with lycopene-rich oleoresin from tomato peels industrial by-product, during accelerated shelf-life storage.

    Science.gov (United States)

    Kehili, Mouna; Choura, Sirine; Zammel, Ayachi; Allouche, Noureddine; Sayadi, Sami

    2018-04-25

    Tomato peels by-product from a Tunisian industry was used for the extraction of lycopene-rich oleoresin using hexane solvent maceration. Tomato peels oleoresin, TPO, exhibited competitive free radicals scavenging activity with synthetic antioxidants. The efficacy of TPO in stabilizing refined olive (ROO) and sunflower (RSO) oils was investigated for five months, under accelerated shelf-life, compared to the synthetic antioxidant, butylated hydroxytoluene (BHT). TPO was added to ROO and RSO at four different concentrations, namely 250, 500, 1000 and 2000 µg/g and BHT standard at 200 µg/g. Lipid oxidation was tracked by measuring the peroxide value, acidity, conjugated dienes and trienes. Results suggested the highest efficiency of 250 µg/g and 2000 µg/g of TPO, referring to 5 µg/g and 40 µg/g of lycopene, for the oxidative stabilization of ROO and RSO, respectively. The protective effect of TPO against the primary oxidation of these refined oils was significantly correlated to their lycopene contents. Copyright © 2017 Elsevier Ltd. All rights reserved.

  8. Detection of titanium oxide in the atmosphere of a hot Jupiter

    Science.gov (United States)

    Sedaghati, Elyar; Boffin, Henri M. J.; MacDonald, Ryan J.; Gandhi, Siddharth; Madhusudhan, Nikku; Gibson, Neale P.; Oshagh, Mahmoudreza; Claret, Antonio; Rauer, Heike

    2017-09-01

    As an exoplanet transits its host star, some of the light from the star is absorbed by the atoms and molecules in the planet’s atmosphere, causing the planet to seem bigger; plotting the planet’s observed size as a function of the wavelength of the light produces a transmission spectrum. Measuring the tiny variations in the transmission spectrum, together with atmospheric modelling, then gives clues to the properties of the exoplanet’s atmosphere. Chemical species composed of light elements—such as hydrogen, oxygen, carbon, sodium and potassium—have in this way been detected in the atmospheres of several hot giant exoplanets, but molecules composed of heavier elements have thus far proved elusive. Nonetheless, it has been predicted that metal oxides such as titanium oxide (TiO) and vanadium oxide occur in the observable regions of the very hottest exoplanetary atmospheres, causing thermal inversions on the dayside. Here we report the detection of TiO in the atmosphere of the hot-Jupiter planet WASP-19b. Our combined spectrum, with its wide spectral coverage, reveals the presence of TiO (to a confidence level of 7.7σ), a strongly scattering haze (7.4σ) and sodium (3.4σ), and confirms the presence of water (7.9σ) in the atmosphere.

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

    Science.gov (United States)

    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

    2011-02-01

    A detailed understanding of the sources, transformations and fates of organic species in the environment is crucial because of the central roles that they play in human health, biogeochemical cycles and the 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, a quantity that always increases with oxidation, and is readily measured using state-of-the-art analytical techniques. Field and laboratory measurements of the average carbon oxidation state, 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.

  10. Controlled growth of copper oxide nanostructures by atmospheric pressure micro-afterglow

    Science.gov (United States)

    Altaweel, A.; Filipič, G.; Gries, T.; Belmonte, T.

    2014-12-01

    A large variety of copper oxide nanostructures encompassing nanodots, nanowires and nanowalls, sometimes organized in ;cabbage-like; architectures, are grown locally by direct oxidation of copper thin films using the micro-afterglow of an Ar-O2 microwave plasma operating at atmospheric pressure. Morphology, structure and composition of the oxidized copper thin films are characterized by X-ray diffraction, secondary ion mass spectrometry and scanning electron microscopy. The concentric areas where each kind of nanostructures is found are defined by both their radial position with respect to the afterglow centre and by experimental conditions. A growth mechanism is proposed, based on stress-induced outward migration of copper ions. The development of stress gradients is caused by the formation of a copper oxide scale layer. If copper oxide nanowires can be grown as in thermal oxidation processes, micro-afterglow conditions offer novel nanostructures and nano-architectures.

  11. Bolide impacts and the oxidation state of carbon in the Earth's early atmosphere

    Science.gov (United States)

    Kasting, J. F.

    1992-01-01

    A one-dimensional photochemical model was used to examine the effect of bolide impacts on the oxidation state of Earth's primitive atmosphere. The impact rate should have been high prior to 3.8 Ga before present, based on evidence derived from the Moon. Impacts of comets or carbonaceous asteroids should have enhanced the atmospheric CO/CO2 ratio by bringing in CO ice and/or organic carbon that can be oxidized to CO in the impact plume. Ordinary chondritic impactors would contain elemental iron that could have reacted with ambient CO2 to give CO. Nitric oxide (NO) should also have been produced by reaction between ambient CO2 and N2 in the hot impact plumes. High NO concentrations increase the atmospheric CO/CO2 ratio by increasing the rainout rate of oxidized gases. According to the model, atmospheric CO/CO2 ratios of unity or greater are possible during the first several hundred million years of Earth's history, provided that dissolved CO was not rapidly oxidized to bicarbonate in the ocean. Specifically, high atmospheric CO/CO2 ratios are possible if either: (1) the climate was cool (like today's climate), so that hydration of dissolved CO to formate was slow, or (2) the formate formed from CO was efficiently converted into volatile, reduced carbon compounds, such as methane. A high atmospheric CO/CO2 ratio may have helped to facilitate prebiotic synthesis by enhancing the production rates of hydrogen cyanide and formaldehyde. Formaldehyde may have been produced even more efficiently by photochemical reduction of bicarbonate and formate in Fe(++)-rich surface waters.

  12. 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%.

  13. Atmospheric methane oxidizers are present and active in Canadian high Arctic soils

    NARCIS (Netherlands)

    Martineau, Christine; Pan, Y.; Bodrossy, Levente; Yergeau, E.; Whyte, Lyle G.; Greer, Charles W.

    2014-01-01

    The melting of permafrost and the associated potential for methane emissions to the atmosphere are major concerns in the context of global warming. However, soils can also represent a significant sink for methane through the activity of methane-oxidizing bacteria (MOB). In this study, we looked at

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

    NARCIS (Netherlands)

    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

  15. Meteorite Atmospheric Entry Reproduced in Plasmatron II: Iron Oxidation State Change Probed by Xanes

    Science.gov (United States)

    Giuli, G.; Lepore, G. O.; Pittarello, L.; McKibbin, S.; Goderis, S.; Soens, B.; Bariselli, F.; Barros Dias, B. R.; Zavalan, F. L.; Magin, T.; Helber, B.; Claeys, P.

    2017-09-01

    Heating experiments are one of the approaches used to investigate those changes experienced by meteoroids during their atmospheric entry. In this work, we are going to present the preliminary results from scanning electron microscopy and X-ray Adsorption Spectroscopy, in order to quantify the oxidation state of Fe produced in the VKI Plasmatron.

  16. 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 constan...

  17. Degradation of superconducting Nb/NbN films by atmospheric oxidation

    Energy Technology Data Exchange (ETDEWEB)

    Henry, Michael David; Wolfley, Steven L.; Young, Travis Ryan; Monson, Todd; Pearce, Charles Joseph; Lewis, Rupert M.; Clark, Blythe; Brunke, Lyle Brent; Missert, Nancy A.

    2017-03-01

    Niobium and niobium nitride thin films are transitioning from fundamental research toward wafer scale manufacturing with technology drivers that include superconducting circuits and electronics, optical single photon detectors, logic, and memory. Successful microfabrication requires precise control over the properties of sputtered superconducting films, including oxidation. Previous work has demonstrated the mechanism in oxidation of Nb and how film structure could have deleterious effects upon the superconducting properties. This study provides an examination of atmospheric oxidation of NbN films. By examination of the room temperature sheet resistance of NbN bulk oxidation was identified and confirmed by secondary ion mass spectrometry. As a result, Meissner magnetic measurements confirmed the bulk oxidation not observed with simple cryogenic resistivity measurements.

  18. Investigation of MVK oxidation by OH in the atmosphere simulation chamber SAPHIR

    Science.gov (United States)

    Fuchs, Hendrik; Andres, Stefanie; Bohn, Birger; Häseler, Rolf; Hofzumahaus, Andreas; Holland, Frank; Li, Xin; Kaminski, Martin; Novelli, Anna; Rohrer, Franz; Tillmann, Ralf; Wegener, Robert; Wahner, Andreas

    2017-04-01

    Recent field campaigns showed concentrations of hydroxyl radical (OH) up to a factor of ten larger than predicted by current chemical models for high OH reactivity and low concentrations of nitric oxide (NO). These discrepancies were observed in forests, where isoprene oxidation turnover rates were large. Methyl-vinyl-ketone (MVK) is one of the major first generation products of isoprene oxidation. Here, we present the investigation of the MVK oxidation mechanism at different nitric oxide concentrations in the atmosphere simulation chamber SAPHIR in Juelich, Germany. Measurements of trace gases included a full set of accurate and precise radical measurements. Results of the experiments are compared to model predictions using the Master Chemical Mechanism and recently suggested new reaction pathways.

  19. Fast low-temperature plasma reduction of monolayer graphene oxide at atmospheric pressure

    Science.gov (United States)

    Bodik, Michal; Zahoranova, Anna; Micusik, Matej; Bugarova, Nikola; Spitalsky, Zdenko; Omastova, Maria; Majkova, Eva; Jergel, Matej; Siffalovic, Peter

    2017-04-01

    We report on an ultrafast plasma-based graphene oxide reduction method superior to conventional vacuum thermal annealing and/or chemical reduction. The method is based on the effect of non-equilibrium atmospheric-pressure plasma generated by the diffuse coplanar surface barrier discharge in proximity of the graphene oxide layer. As the reduction time is in the order of seconds, the presented method is applicable to the large-scale production of reduced graphene oxide layers. The short reduction times are achieved by the high-volume power density of plasma, which is of the order of 100 W cm-3. Monolayers of graphene oxide on silicon substrate were prepared by a modified Langmuir-Schaefer method and the efficient and rapid reduction by methane and/or hydrogen plasma was demonstrated. The best results were obtained for the graphene oxide reduction in hydrogen plasma, as verified by x-ray photoelectron spectroscopy and Raman spectroscopy.

  20. 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).

  1. Measurement-based modeling of daytime and nighttime oxidation of atmospheric mercury

    Science.gov (United States)

    Tas, Eran; Gabay, Maor; Peleg, Mordechai; Fredj, Erick

    2017-04-01

    Accurate characterization of gaseous elemental mercury (GEM) chemical oxidation pathways and their kinetics is critically important for assessing the transfer of atmospheric mercury to bioaquatic systems. Recent comprehensive field measurements have suggested that the nitrate radical (NO3) plays a role in efficient nighttime oxidation of GEM, and that the role of the hydroxyl radical (OH) as a GEM oxidant has been underestimated. We used the CAABA/MECCA chemical box model and additional kinetic calculations to analyze these measurement results, in order to investigate the nighttime and daytime oxidation of GEM. We assumed a second-order reaction for the NO3 induced nighttime oxidation of GEM. Our analysis demonstrated that nighttime oxidation of GEM has to be included in the model to account for the measured variations in nighttime reactive gaseous mercury (RGM) concentration. A lower limit and best-fit rate constant for GEM nighttime oxidation are provided. To the best of our knowledge, this is the first time that a rate for nighttime oxidation of GEM has been determined based on field measurements. Our analysis further indicates that OH has a much more important role in GEM oxidation than commonly considered. A lower-limit rate constant for the OH-RGM reaction is provided.

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

    Science.gov (United States)

    Augustin, Matthias; Fenske, Daniela; Bardenhagen, Ingo; Westphal, Anne; Knipper, Martin; Plaggenborg, Thorsten; Kolny-Olesiak, Joanna; Parisi, Jürgen

    2015-01-01

    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 Mn (x) (+) 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 MnO x 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 MnO x species on the calcination temperature and the presence of an oxidizing or neutral atmosphere. Furthermore, to demonstrate the application potential of the synthesized MnO x 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.

  3. 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.

  4. Evidence for an increase in the oxidative capacity of the atmosphere in the late twentieth century

    Science.gov (United States)

    Newland, Mike; Martinerie, Patricia; Witrant, Emmanuel; Helmig, Detlev; Worton, David; Hogan, Chris; Sturges, Bill; Reeves, Claire

    2016-04-01

    The hydroxyl radical, OH, is the dominant sink for the majority of trace gases in the troposphere. Thus, it plays a major role in controlling atmospheric chemical composition. However despite this importance there remains much uncertainty as to whether concentrations of OH have changed in the background atmosphere in recent decades. It has previously been reported that recent levels of OH in the troposphere (1997-2008) are well buffered against changes in atmospheric composition (Montzka et al., 2011). We present two independent records that suggest that there was a significant increase in concentrations of the OH radical in the northern hemisphere during the last two decades of the twentieth century. Measurements from Greenland firn air of the changing ratios of n-butane, iso-butane, n-pentane and iso-pentane were compared using a photochemical clock method. Using these changing ratios we calculate an increase in the chemical processing of the air (i.e. [OH].t) between 1980 and 2000. Assuming t to be constant this provides a semi-quantitative historic record of OH concentrations. Furthermore, measurements of three alkyl nitrates (also from Greenland firn air), secondary oxidation products of the alkanes, suggest an increase in the [NO]/[HO2] ratio in the background atmosphere. This could be indicative of increasing NOx concentrations during this period, which would be consistent with increasing [OH]. These two records are further corroborated by comparison with the long term trend in increasing ozone mixing ratios from background European sites. Knowledge of historic changes to the oxidative capacity of the atmosphere is fundamental to understanding the atmospheric records of trace gases and to determining historic trace gas emissions using top-down approaches. The results presented here have profound implications for our understanding of atmospheric composition in the past, the present and for predicting the future evolution of the atmosphere.

  5. 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

  6. 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...

  7. Calculating the balance between atmospheric CO2 drawdown and organic carbon oxidation in subglacial hydrochemical systems

    Science.gov (United States)

    Graly, Joseph A.; Drever, James I.; Humphrey, Neil F.

    2017-04-01

    In order to constrain CO2 fluxes from biogeochemical processes in subglacial environments, we model the evolution of pH and alkalinity over a range of subglacial weathering conditions. We show that subglacial waters reach or exceed atmospheric pCO2 levels when atmospheric gases are able to partially access the subglacial environment. Subsequently, closed system oxidation of sulfides is capable of producing pCO2 levels well in excess of atmosphere levels without any input from the decay of organic matter. We compared this model to published pH and alkalinity measurements from 21 glaciers and ice sheets. Most subglacial waters are near atmospheric pCO2 values. The assumption of an initial period of open system weathering requires substantial organic carbon oxidation in only 4 of the 21 analyzed ice bodies. If the subglacial environment is assumed to be closed from any input of atmospheric gas, large organic carbon inputs are required in nearly all cases. These closed system assumptions imply that order of 10 g m-2 y-1 of organic carbon are removed from a typical subglacial environment—a rate too high to represent soil carbon built up over previous interglacial periods and far in excess of fluxes of surface deposited organic carbon. Partial open system input of atmospheric gases is therefore likely in most subglacial environments. The decay of organic carbon is still important to subglacial inorganic chemistry where substantial reserves of ancient organic carbon are found in bedrock. In glaciers and ice sheets on silicate bedrock, substantial long-term drawdown of atmospheric CO2 occurs.

  8. The Atmospheric Oxidation of Volatile Organic Compounds Through Hydrogen Shift Reactions

    DEFF Research Database (Denmark)

    Knap, Hasse Christian

    In this thesis the unimolecular hydrogen transfer reactions (H-shift) in peroxy and acyl peroxy radicals derived from the atmospheric oxidation of volatile organic compounds (VOC) have been investigated. A unimolecular isomerization reaction where a hydrogen atom is moved internally within...... the reaction rate constants of the H-shift reactions. The autoxidation of volatile organic compounds is an important oxidation mechanism that produces secondary organic aerosols (SOA) and recycles hydroxyl (OH) radicals. The autoxidation cycle produces a second generation peroxy radical (OOQOOH) through...

  9. CO oxidation and O2 removal on meteoric material in Venus' atmosphere

    Science.gov (United States)

    Frankland, Victoria L.; James, Alexander D.; Carrillo-Sánchez, Juan Diego; Nesvorný, David; Pokorný, Petr; Plane, John M. C.

    2017-11-01

    The heterogeneous oxidation of CO by O2 on olivine, Fe sulfate and Fe oxide particles was studied using a flow tube apparatus between 300 and 680 K. These particles were chosen as possible analogues of unablated cosmic dust and meteoric smoke in Venus' atmosphere. On olivine and Fe oxides, the rate of CO oxidation to CO2 only becomes significant above 450 K. For iron sulfates, CO2 production was not observed until these dust analogues had decomposed into iron oxides at ∼ 540 K. The CO oxidation rate increases significantly with a higher Fe content in the dust, implying that oxidation occurs through Fe active sites (no reaction was observed on Mg2SiO4). The oxidation kinetics can be explained by CO reacting with chemi-sorbed O2 through an Eley-Rideal mechanism, which is supported by electronic structure calculations. Uptake coefficients were measured from 450 to 680 K, yielding: log10(γ (CO on MgFeSiO4)) = (2.9 ± 0.1) × 10-3 T(K) - (8.2 ± 0.1); log10(γ (CO on Fe2SiO4)) = (2.3 ± 0.3) × 10-3 T(K) - (7.7 ± 0.2); log10(γ (CO on FeOOH/Fe2O3)) = (5.6 ± 0.8) × 10-3T(K) - (9.3 ± 0.4). A 1-D atmospheric model of Venus was then constructed to explore the role of heterogeneous oxidation. The cosmic dust input to Venus, mostly originating from Jupiter Family Comets, is around 32 tonnes per Earth day. A chemical ablation model was used to show that ∼34% of this incoming mass ablates, forming meteoric smoke particles which, together with unablated dust particles, provide a significant surface for the heterogeneous oxidation of CO to CO2 in Venus' troposphere. This process should cause almost complete removal of O2 below 40 km, but have a relatively small impact on the CO mixing ratio (since CO is in large excess over O2). Theoretical quantum calculations indicate that the gas-phase oxidation of CO by SO2 in the lower troposphere is not competitive with the heterogeneous oxidation of CO. Finally, the substantial number density of meteoric smoke particles predicted

  10. Atmospheric oxidation of halogenated aromatics: comparative analysis of reaction mechanisms and reaction kinetics.

    Science.gov (United States)

    Kovacevic, Goran; Sabljic, Aleksandar

    2017-03-22

    Atmospheric transport is the major route for global distribution of semi-volatile compounds such as halogenated aromatics as well as their major exposure route for humans. Their major atmospheric removal process is oxidation by hydroxyl radicals. There is very little information on the reaction mechanism or reaction-path dynamics of atmospheric degradation of halogenated benzenes. Furthermore, the measured reaction rate constants are missing for the range of environmentally relevant temperatures, i.e. 230-330 K. A series of recent theoretical studies have provided those valuable missing information for fluorobenzene, chlorobenzene, hexafluorobenzene and hexachlorobenzene. Their comparative analysis has provided additional and more general insight into the mechanism of those important tropospheric degradation processes as well as into the mobility, transport and atmospheric fate of halogenated aromatic systems. It was demonstrated for the first time that the addition of hydroxyl radicals to monohalogenated as well as to perhalogenated benzenes proceeds indirectly, via a prereaction complex and its formation and dynamics have been characterized including the respective transition-state. However, in fluorobenzene and chlorobenzene reactions hydroxyl radical hydrogen is pointing approximately to the center of the aromatic ring while in the case of hexafluorobenzene and hexachlorobenzene, unexpectedly, the oxygen is directed towards the center of the aromatic ring. The reliable rate constants are now available for all environmentally relevant temperatures for the tropospheric oxidation of fluorobenzene, chlorobenzene, hexafluorobenzene and hexachlorobenzene while pentachlorophenol, a well-known organic micropollutant, seems to be a major stable product of tropospheric oxidation of hexachlorobenzene. Their calculated tropospheric lifetimes show that fluorobenzene and chlorobenzene are easily removed from the atmosphere and do not have long-range transport potential while

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

    Science.gov (United States)

    Hampson, R. F., Jr.

    1980-01-01

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

  12. Atmospheric oxygen regulation at low Proterozoic levels by incomplete oxidative weathering of sedimentary organic carbon.

    Science.gov (United States)

    Daines, Stuart J; Mills, Benjamin J W; Lenton, Timothy M

    2017-02-02

    It is unclear why atmospheric oxygen remained trapped at low levels for more than 1.5 billion years following the Paleoproterozoic Great Oxidation Event. Here, we use models for erosion, weathering and biogeochemical cycling to show that this can be explained by the tectonic recycling of previously accumulated sedimentary organic carbon, combined with the oxygen sensitivity of oxidative weathering. Our results indicate a strong negative feedback regime when atmospheric oxygen concentration is of order pO 2 ∼0.1 PAL (present atmospheric level), but that stability is lost at pO 2 <0.01 PAL. Within these limits, the carbonate carbon isotope (δ 13 C) record becomes insensitive to changes in organic carbon burial rate, due to counterbalancing changes in the weathering of isotopically light organic carbon. This can explain the lack of secular trend in the Precambrian δ 13 C record, and reopens the possibility that increased biological productivity and resultant organic carbon burial drove the Great Oxidation Event.

  13. Unexpected increase in the oxidation capacity of the urban atmosphere of Madrid, Spain

    Science.gov (United States)

    Saiz-Lopez, A.; Borge, R.; Notario, A.; Adame, J. A.; Paz, D. De La; Querol, X.; Artíñano, B.; Gómez-Moreno, F. J.; Cuevas, C. A.

    2017-04-01

    Atmospheric oxidants such as ozone (O3), hydroxyl and nitrate radicals (OH and NO3) determine the ability of the urban atmosphere to process organic and inorganic pollutants, which have an impact on air quality, environmental health and climate. Madrid city has experienced an increase of 30-40% in ambient air O3 levels, along with a decrease of 20-40% in NO2, from 2007 to 2014. Using air pollution observations and a high-resolution air quality model, we find a large concentration increase of up to 70% and 90% in OH and NO3, respectively, in downtown Madrid (domain-wide average increase of 10% and 32% for OH and NO3, respectively). The results also show an 11% reduction in the nitric acid concentrations, leading to a remarkable denoxification of this urban atmosphere with implications for lower PM2.5 levels and nitrogen input into ecosystems. This study suggests that projected worldwide NOx emission reductions, following air quality standards, will lead to important changes in the oxidizing capacity of the atmosphere in and around large cities.

  14. High temporal and spatial variability of atmospheric-methane oxidation in Alpine glacier-forefield soils.

    Science.gov (United States)

    Chiri, Eleonora; Nauer, Philipp A; Rainer, Edda-Marie; Zeyer, Josef; Schroth, Martin H

    2017-07-07

    Glacier-forefield soils can provide a substantial sink for atmospheric CH4, facilitated by aerobic methane-oxidizing bacteria (MOB). However, MOB activity, abundance, and community structure may be affected by soil age, location in different forefield landforms, and temporal fluctuations in soil-physical parameters. We assessed spatial and temporal variability of atmospheric CH4 oxidation in an Alpine glacier forefield during the snow-free season 2013. We quantified CH4 flux in soils of increasing age and in different landforms (sandhill, terrace, floodplain) using soil-gas-profile and static flux-chamber methods. To determine MOB abundance and community structure, we employed pmoA-gene-based quantitative PCR and targeted-amplicon sequencing. Uptake of CH4 increased in magnitude and decreased in variability with increasing soil age. Sandhill soils exhibited CH4 uptake ranging from -0.03- -3.7 mg CH4 m-2 d-1 Floodplain and terrace soils exhibited smaller uptake and even intermittent CH4 emissions. Linear mixed-effect models indicated that soil age and landform were dominating factors shaping CH4 flux, followed by cumulative rainfall (weighted sum ≤ 4 d prior to sampling). Of 31 MOB operational taxonomic units retrieved, ∼30% were potentially novel, and ∼50% were affiliated with Upland Soil Clusters gamma and alpha. The MOB community structures in floodplain and terrace soils were nearly identical, but differed significantly from highly variable sandhill-soil communities. We conclude that soil age and landform modulate the soil CH4 sink strength in glacier forefields, and recent rainfall affects its short-term variability. This should be taken into account when including this environment in future CH4 inventories.Importance Oxidation of methane (CH4) in well-drained, "upland" soils is an important mechanism for the removal of this potent greenhouse gas from the atmosphere. It is largely mediated by aerobic, methane-oxidizing bacteria (MOB). Whereas there is

  15. Session 6: Stability and performance of metal oxide catalysts during oxidation of ammonia in steam atmosphere at high pressure

    Energy Technology Data Exchange (ETDEWEB)

    Armbruster, U.; Martin, A.; Radnik, J.; Schneider, M. [Institut fur Angewandte Chemie Berlin-Adlershof e.V., Berlin (Germany)

    2004-07-01

    The aim of this work was to test supported and bulk transition metal oxide catalysts for end of pipe-oxidation of ammonia at high pressure in saturated steam. Reaction engineering aspects are also discussed. In fact, the experimental results show that bulk copper chromites are best performing catalysts for ammonia destruction at temperatures around 300 C and pressures at ca. 50 bar in steam atmosphere. No leaching occurred under the applied conditions, however, influence of phase behaviour of water is crucial to catalyst lifetime. Ammonia is exclusively converted to nitrogen. Only a slight loss in activity was observed in long-term tests that is mainly due to small decrease in active surface area. (authors)

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

    Directory of Open Access Journals (Sweden)

    Ieda Caminha

    2004-03-01

    Full Text Available 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 °C and 700 °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 (Fe2O3, Fe3O4 and FeO 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.

  17. OXIDATIVE DNA DAMAGE FROM POTASSIUM BROMATE EXPOSURE IN LONG-EVANS RATS IS NOT ENHANCED BY A MIXTURE OF DRINKING WATER DISINFECTION BY-PRODUCTS

    Science.gov (United States)

    Public drinking water treated with chemical disinfectants contains a complex mixture of disinfection by-products (DBPs) for which the relative toxicity of the mixtures needs to be characterized to accurately assess risk. Potassium bromate (KBrO3) is a by-product from ozonation of...

  18. Atmosphere-ocean-lithosphere interactions during the Great Oxidation Event: insights from zircon δ18O

    Science.gov (United States)

    Spencer, C. J.; Partin, C. A.; Kirkland, C.; Shiels, C.; Raub, T. D.; Kinny, P.

    2016-12-01

    The Great Oxidation Event (GOE) records a precipitous atmospheric oxygen rise, perhaps by as much as three to four orders of magnitude within a few million years. The timescale of the GOE is primarily constrained by the rapid loss of mass-independently fractionated sulfur isotopes. The drastic surface changes associated with the GOE are reflected by the appearance of marine sulfate and manganese deposits, as well as increased redox-sensitive trace metal abundances in banded iron formations and shale. Each of these manifestations is recorded at the atmosphere-lithosphere or atmosphere-ocean interface. However, how the GOE affected the lithosphere beyond the atmosphere interface has received little attention to date. We present zircon δ18O data from Paleoproterozoic sedimentary successions in Western Australia and Canada that display a step-change from the isotopically distinct reservoir with high δ18O that was incorporated into subduction zone magmas. One likely candidate is marine sulfate evaporite deposits, which appear with the GOE. The incorporation of this enriched δ18O reservoir would have facilitated the step change seen in the zircon δ18O record. This signal may also be present to a much lower degree associated with the "whiffs" of atmospheric oxygen prior to the GOE.

  19. 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

  20. Reagent use efficiency with removal of nitrogen from pig slurry via struvite: A study on magnesium oxide and related by-products.

    Science.gov (United States)

    Romero-Güiza, M S; Tait, S; Astals, S; Del Valle-Zermeño, R; Martínez, M; Mata-Alvarez, J; Chimenos, J M

    2015-11-01

    Controlled struvite formation has been attracting increasing attention as a near mature technology to recover nutrients from wastewater. However, struvite feasibility is generally limited by the high cost of chemical reagents. With the aim to understand and control reagent use efficiency, experiments and equilibrium model simulations examined inorganic nitrogen (TAN) removal from pig manure via struvite with added magnesium and phosphate reagents. Four industrial magnesium oxide (MgO), a commercial product and three by-products from magnesite calcination, were tested with phosphate added as a highly soluble potassium salt. TAN removal extents with the MgOs ranged from 47 to 72%, with the highest grade MgO providing the greatest extent of TAN removal. However, model analysis showed that all the MgO reagents were poorly soluble (only about 40% of added magnesium actually dissolved). The model results suggested that this poor dissolution was due to kinetic limitations, not solubility constraints. A further set of additional reagents (termed stabilization agents) were prepared by pre-treating the MgO reagents with phosphoric acid, and were tested separately as a source of both magnesium and phosphate. Results showed that acid pre-treatment of moderate to highly reactive MgOs (soft to medium-burnt) primarily formed bobierrite as the stabilizing agent, whereas the pre-treatment of very low reactivity MgOs (dead-burnt) mostly formed newberyite. The newberyite stabilizing agents achieved very high TAN removal extents of about 80%, which is significant, considering that these were formed from dead-burnt/low-grade MgOs. However, the bobierrite stabilizing agents achieved a substantially lower TAN removal extent than their medium-to-high reactivity precursor MgOs. Again, model analysis showed that the bobierrite stabilizing agents were poorly soluble, due to kinetic limitations, not solubility constraints. In contrast, the model suggested that the newberyite stabilizing

  1. 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

  2. Isotopic evidence of multiple controls on atmospheric oxidants over climate transitions

    Science.gov (United States)

    Geng, Lei; Murray, Lee T.; Mickley, Loretta J.; Lin, Pu; Fu, Qiang; Schauer, Andrew J.; Alexander, Becky

    2017-06-01

    The abundance of tropospheric oxidants, such as ozone (O3) and hydroxyl (OH) and peroxy radicals (HO2 + RO2), determines the lifetimes of reduced trace gases such as methane and the production of particulate matter important for climate and human health. The response of tropospheric oxidants to climate change is poorly constrained owing to large uncertainties in the degree to which processes that influence oxidants may change with climate and owing to a lack of palaeo-records with which to constrain levels of atmospheric oxidants during past climate transitions. At present, it is thought that temperature-dependent emissions of tropospheric O3 precursors and water vapour abundance determine the climate response of oxidants, resulting in lower tropospheric O3 in cold climates while HOx (= OH + HO2 + RO2) remains relatively buffered. Here we report observations of oxygen-17 excess of nitrate (a proxy for the relative abundance of atmospheric O3 and HOx) from a Greenland ice core over the most recent glacial-interglacial cycle and for two Dansgaard-Oeschger events. We find that tropospheric oxidants are sensitive to climate change with an increase in the O3/HOx ratio in cold climates, the opposite of current expectations. We hypothesize that the observed increase in O3/HOx in cold climates is driven by enhanced stratosphere-to-troposphere transport of O3, and that reactive halogen chemistry is also enhanced in cold climates. Reactive halogens influence the oxidative capacity of the troposphere directly as oxidants themselves and indirectly via their influence on O3 and HOx. The strength of stratosphere-to-troposphere transport is largely controlled by the Brewer-Dobson circulation, which may be enhanced in colder climates owing to a stronger meridional gradient of sea surface temperatures, with implications for the response of tropospheric oxidants and stratospheric thermal and mass balance. These two processes may represent important, yet relatively

  3. 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

    The oxidative stability and sensory quality of chicken breast (m. pectoralis) and thigh (m. peroneus longus) stored in high-oxygen modified atmosphere (MAP-O), non-oxygen modified atmosphere (MAP-N), or vacuum for up to 9 days at 5°C were investigated. Protein thiol concentration in breasts...... in MAP-O than breast, indicating that the negative effect MAP-O may have on the oxidative stability and sensory quality of meat varies between different muscles....

  4. Theoretical study for OH radical-initiated atmospheric oxidation of ethyl acrylate.

    Science.gov (United States)

    Sun, Yanhui; Zhang, Qingzhu; Hu, Jingtian; Chen, Jianmin; Wang, Wenxing

    2015-01-01

    OH radical-initiated atmospheric oxidation of ethyl acrylate (ethyl 2-propenoate, EA) has been investigated by performing density functional theory (DFT) calculations. Optimizations of the reactants, intermediates, transition states and products were carried out at the MPWB1K/6-31+G(d,p) level. Single-point energy calculations were performed at the MPWB1K/6-311+G(3df,2p) level of theory. The detailed oxidation mechanism was presented and discussed. The results show that the OH addition is more energetically favorable than the H abstraction. Rice-Ramsperger-Kassel-Marcus (RRKM) theory was used to predict the rate constants over the possible atmospheric temperature range of 180-370 K. The Arrhenius expression adequately describes the total rate constant: k(EA+OH)=(1.71×10(-12))exp(805.42/T)cm(3) molecule(-1) s(-1). At 298 K, the atmospheric lifetime of ethyl acrylate determined by OH radicals is about 16.2h. In order to find out the effect of alkyl substitution on the reaction activity, rate constants for the reactions of methyl acrylate, methyl methacrylate and butyl acrylate with OH radicals were also discussed. Calculation results show that the reaction activity may increase with the increased electron-donating substitution for electrophilic addition reaction. Copyright © 2014 Elsevier Ltd. All rights reserved.

  5. Oxidation Behavior of Titanium Carbonitride Coating Deposited by Atmospheric Plasma Spray Synthesis

    Science.gov (United States)

    Zhu, Lin; He, Jining; Yan, Dianran; Liao, Hanlin; Zhang, Nannan

    2017-10-01

    As a high-hardness and anti-frictional material, titanium carbonitride (TiCN) thick coatings or thin films are increasingly being used in many industrial fields. In the present study, TiCN coatings were obtained by atmospheric plasma spray synthesis or reactive plasma spray. In order to promote the reaction between the Ti particles and reactive gases, a home-made gas tunnel was mounted on a conventional plasma gun to perform the spray process. The oxidation behavior of the TiCN coatings under different temperatures in static air was carefully investigated. As a result, when the temperature was over 700 °C, the coatings suffered from serious oxidation, and finally they were entirely oxidized to the TiO2 phase at 1100 °C. The principal oxidation mechanism was clarified, indicating that the oxygen can permeate into the defects and react with TiCN at high temperatures. In addition, concerning the use of a TiCN coating in high-temperature conditions, the microhardness of the oxidized coatings at different treatment temperatures was also evaluated.

  6. Conductivity of SrTiO3 based oxides in the reducing atmosphere at high temperature

    DEFF Research Database (Denmark)

    Hashimoto, Shin-Ichi; Poulsen, Finn Willy; Mogensen, Mogens Bjerg

    2007-01-01

    The conductivities of several donor-doped SrTiO3 based oxides, which were prepared in air, were studied in a reducing atmosphere at high temperature. The conductivities of all specimens increased slowly with time at 1000 degrees C in 9% H-2/N-2, even after 100 h. Nb-doped SrTiO3 showed relatively...... at 500-800 degrees C, while that of La-doped SrTiO3 dropped immediately on exposure to air. The conduction behavior of Nb-doped SrTiO3 was explained by reduction of Ti4+ and/or Nb5+ and the relatively slow oxygen diffusibility. (c) 2006 Elsevier B.V. All rights reserved.......The conductivities of several donor-doped SrTiO3 based oxides, which were prepared in air, were studied in a reducing atmosphere at high temperature. The conductivities of all specimens increased slowly with time at 1000 degrees C in 9% H-2/N-2, even after 100 h. Nb-doped SrTiO3 showed relatively...... fast reduction and high conductivity compared with the other SrTiO3 based oxides. The conductivity of Nb-doped SrTiO3 was ca. 50 S cm(-1) at 500 degrees C after reduction at 1200 degrees C. After strong reduction, the conductivity of Nb-doped SrTiO3 was almost independent of the oxygen partial pressure...

  7. Oxidation of c60 aerosols by atmospherically relevant levels of o3.

    Science.gov (United States)

    Tiwari, Andrea J; Morris, John R; Vejerano, Eric P; Hochella, Michael F; Marr, Linsey C

    2014-01-01

    Atmospheric processing of carbonaceous nanoparticles (CNPs) may play an important role in determining their fate and environmental impacts. This work investigates the reaction between aerosolized C60 and atmospherically relevant mixing ratios of O3 at differing levels of humidity. Results indicate that C60 is oxidized by O3 and forms a variety of oxygen-containing functional groups on the aerosol surface, including C60O, C60O2, and C60O3. The pseudo-first-order reaction rate between C60 and O3 ranges from 9 × 10(-6) to 2 × 10(-5) s(-1). The reaction is likely to be limited to the aerosol surface. Exposure to O3 increases the oxidative stress exerted by the C60 aerosols as measured by the dichlorofluorescein acellular assay but not by the uric acid, ascorbic acid, glutathione, or dithiothreitol assays. The initial prevalence of C60O and C60O2 as intermediate products is enhanced at higher humidity, as is the surface oxygen content of the aerosols. These results show that C60 can be oxidized when exposed to O3 under ambient conditions, such as those found in environmental, laboratory, and industrial settings.

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

    OpenAIRE

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

    2015-01-01

    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, research...

  9. Historical mining of soil nitrogen was a likely source of atmospheric nitrous oxide

    Science.gov (United States)

    Davidson, E. A.

    2009-12-01

    Prior to the advent of use of synthetic nitrogen (N) fertilizers, agricultural expansion was often followed by depletion of soil carbon and N stocks. While the mining of soil N permits a period of productive agriculture, it may also result in transfers of soil N to groundwater, surface water, and the atmosphere. Atmospheric nitrous oxide (N2O) concentrations have been increasing since the industrial revolution and currently account for 6% of total anthropogenic radiative forcing. Microbial production in soils is the dominant N2O source. The use of synthetic N fertilizers alone cannot account for the historical trends of atmospheric concentrations of N2O, because the increase in atmospheric N2O began well before N fertilizers were widely used. Here, I analyze atmospheric concentrations, industrial sources of N2O, and fertilizer and manure production since 1860. Prior to 1960, agricultural expansion, including livestock production, appears to have caused globally significant mining of soil N, fuelling a steady increase in atmospheric N2O. Post 1960, the rate of the increase rose, due to accelerating use of synthetic N fertilizers. Using a regression model, I show that 2% of manure N and 2.5% of fertilizer N were converted to N2O between 1860 and 2005; these percentage contributions explain the entire pattern of increasing N2O concentrations over this period. Consideration of processes that re-concentrate soil N, such as manure production by livestock, improved hind-casting of N2O emissions. Any process in the past, present, or future that causes either accumulation or depletion of N reservoirs in soils or sediments could affect N2O emissions. As animal protein consumption in human diets increases globally, management of manure will be an important component of future mitigation efforts to reduce anthropogenic N2O sources.

  10. The Influence of Atmosphere on the Oxidation of Ground Walnut During Storage at 20 °C

    Directory of Open Access Journals (Sweden)

    Rajko Vidrih

    2012-01-01

    Full Text Available The aim of this study is to determine the impact of atmosphere on the oxidation of ground walnut during storage at 20 °C. Seven varieties of walnut (Juglans regia L. were ground and stored under O2 or N2 atmospheres in hermetically sealed vials for 10 months at room temperature. Antioxidative potential, total phenolic content, fatty acid composition, and oxidative degradation products were determined after 10 months of storage. Cultivar, atmosphere and cultivar×atmosphere interactions significantly influenced the antioxidative potential. Cultivar and atmosphere significantly influenced the content of total polyphenols, with more polyphenols found in walnut stored in the N2 atmosphere. The mass fraction of unsaturated linolenic acid tended to decrease during storage under the O2 atmosphere; statistically significant differences were only found between individual varieties. The O2 atmosphere also resulted in an increase in the synthesis of oxidative degradation products. Among the degradation products, hexanal was the most abundant volatile compound, followed by 1-octen-3-ol, octanal, as well as the mixture of 2-octenal and 1-octen-3-ol. In general, higher concentrations of these degradation products were found in walnut stored under the O2 atmosphere, although these differences were statistically significant only between individual varieties for some compounds.

  11. Atmospheric oxidation of selected chlorinated alkenes by O3, OH, NO3 and Cl

    Science.gov (United States)

    Zhang, Qun; Chen, Yi; Tong, Shengrui; Ge, Maofa; Shenolikar, Justin; Johnson, Matthew S.; Wang, Yifeng; Tsona, Narcisse T.; Mellouki, Abdelwahid; Du, Lin

    2017-12-01

    An experimental study on the 3-chloro-2-methyl-1-propene (CMP), 2,3-dichloropropene (DCP) and 3,4-dichlorobutene (DCB) reactions with atmospheric oxidants at (298 ± 1) K and atmospheric pressure is reported. Rate constants for the gas phase reactions of the three chlorinated alkenes with O3, OH and NO3 radicals and Cl atom were determined in a 100 L Teflon reactor by gas chromatography with flame ionization detector (GC-FID). The obtained rate constants are (3.03 ± 0.15) × 10-18, (3.83 ± 1.30) × 10-11, (1.99 ± 0.19) × 10-14, and (2.40 ± 0.41) × 10-10 cm3 molecule-1 s-1 for CMP reactions with O3, OH, NO3, and Cl, respectively, (4.62 ± 1.41) × 10-20, (1.37 ± 1.02) × 10-11, (1.45 ± 0.15) × 10-15 and (1.30 ± 0.99) × 10-11 cm3 molecule-1 s-1 for DCP reactions and (2.09 ± 0.24) × 10-19, (1.45 ± 0.59) × 10-11, (3.00 ± 0.82) × 10-16 and (1.91 ± 0.19) × 10-10 cm3 molecule-1 s-1 for DCB reactions. The CMP reaction products were detected and possible reaction mechanisms of their formation were proposed. Chloroacetone was found to be the major product in all four oxidation reactions. The loss process of CMP in the atmosphere is mostly controlled by its reaction with the OH radical during daytime and with NO3 during nighttime, with lifetimes of 3.6 h and 27.9 h respectively. Atmospheric implications of both these reactions and their potential products are discussed.

  12. Coupled Surface-Atmosphere Chemistry of the Martian Peroxide and Perchlorate Oxidants

    Science.gov (United States)

    Atreya, Sushil K.; Wilson, Eric; Encrenaz, Thérèse; Kaiser, Ralf; Mahaffy, Paul

    2017-04-01

    Oxidants play a significant role in planetary habitability. On Mars, while they can be a source of nutrients, they can also destroy surface organics. They may also impact the atmospheric trace gas chemistry. Hydrogen peroxide was first detected in the martian atmosphere in 2003 [1,2], and perchlorates were detected in the surface in 2008 in the polar region [3] and 2012 in the equatorial region [4,5]. Global and seasonal maps of hydrogen peroxide have been generated from regular observations since 2003 [6], while all indications are that perchlorates are ubiquitous on Mars. Homogeneous gas phase chemistry can generally explain the observed atmospheric hydrogen peroxide, but the magnitude of seasonal variation poses a challenge. Heterogeneous chemistry involving airborne dust lifted from the surface and triboelectric processes [6,7] may play a role. Perchlorate formation on Mars is poorly understood, but one thing is clear that the same atmospheric process that works reasonably well for terrestrial perchlorates fails at Mars. An alternative proposal to perchlorate formation in an ancient aqueous environment is an initiation throughout the history of Mars in the surface by radiolysis to source gaseous ClO2 to the atmosphere with subsequent further oxidation [8]. This talk will discuss the current status of oxidant chemistry on Mars in the above context and provide directions for future laboratory and modeling studies. References: [1] Encrenaz, T., et al. (2004) Icarus 170, 424. [2] Clancy, R.T., et al. (2004) Icarus 168, 116. [3] Hecht, M.H., et al. (2009) Science, 325(5936), 64, doi:10.1126/science.1172466. [4] Glavin, D.P., et al. (2013) JGR Planets 118, 1955, doi:10.1002/jgre.20144. [5] Ming, D.W., et al. (2014) Science, 343(6169), doi:10.1126/science.1245267. [6] Encrenaz, T., et al. (2015) A&A. 578, A127 (12pp), DOI: 10.1051/0004-6361/201425448. [7] Atreya, S.K., et al. (2006) Astrobiology 6 (no. 3), 439. [8] Wilson, E.H. et al., (2016) JGR Planets, doi: 10

  13. Atmospheric constraints on 2004 emissions of methane and nitrous oxide in North America from atmospheric measurements and a receptor-oriented modeling framework

    NARCIS (Netherlands)

    Kort, E.A.; Andrews, A.E.; Dlugokencky, E.; Sweeney, C.; Houweling, S.

    2010-01-01

    Methane and nitrous oxide are potent greenhouse gases whose atmospheric abundances have increased significantly in the past 200 years, together accounting for approximately half of the radiative forcing associated with increasing concentrations of carbon dioxide. In order to understand the factors

  14. Application of argon atmospheric cold plasma for indium tin oxide (ITO) based diodes

    Science.gov (United States)

    Akbari Nia, S.; Jalili, Y. Seyed; Salar Elahi, A.

    2017-09-01

    Transparent Conductive Oxide (TCO) layers due to transparency, high conductivity and hole injection capability have attracted a lot of attention. One of these layers is Indium Tin Oxide (ITO). ITO due to low resistance, transparency in the visible spectrum and its proper work function is widely used in the manufacture of organic light emitting diodes and solar cells. One way for improving the ITO surface is plasma treatment. In this paper, changes in surface morphology, by applying argon atmospheric pressure cold plasma, was studied through Atomic Force Microscopic (AFM) image analysis and Fourier Transform Infrared Spectroscopy (FTIR) analysis. FTIR analysis showed functional groups were not added or removed, but chemical bond angle and bonds strength on the surface were changed and also AFM images showed that surface roughness was increased. These factors lead to the production of diodes with enhanced Ohmic contact and injection mechanism which are more appropriate in industrial applications.

  15. Atmospheric-pressure glow plasma synthesis of plasmonic and photoluminescent zinc oxide nanocrystals

    Energy Technology Data Exchange (ETDEWEB)

    Bilik, N., E-mail: bilik006@umn.edu, E-mail: kortshagen@umn.edu; Greenberg, B. L.; Yang, J.; Kortshagen, U. R., E-mail: bilik006@umn.edu, E-mail: kortshagen@umn.edu [Department of Mechanical Engineering, University of Minnesota, Minneapolis, Minnesota 55455 (United States); Aydil, E. S. [Department of Chemical Engineering, University of Minnesota, Minneapolis, Minnesota 55455 (United States)

    2016-06-28

    In this paper, we present a large-volume (non-micro) atmospheric pressure glow plasma capable of rapid, large-scale zinc oxide nanocrystal synthesis and deposition (up to 400 μg/min), whereas in the majority of the literature, nanoparticles are synthesized using micro-scale or filamentary plasmas. The reactor is an RF dielectric barrier discharge with a non-uniform gap spacing. This design encourages pre-ionization during the plasma breakdown, making the discharge uniform over a large volume. The produced zinc oxide nanocrystals typically have diameters ranging from 4 to 15 nm and exhibit photoluminescence at ≈550 nm and localized surface plasmon resonance at ≈1900 cm{sup −1} due to oxygen vacancies. The particle size can be tuned to a degree by varying the gas temperature and the precursor mixing ratio.

  16. Parameterizing soil emission and atmospheric oxidation-reduction in a model of the global biogeochemical cycle of mercury.

    Science.gov (United States)

    Kikuchi, Tetsuro; Ikemoto, Hisatoshi; Takahashi, Katsuyuki; Hasome, Hisashi; Ueda, Hiromasa

    2013-01-01

    Using the GEOS-Chem atmosphere-land-ocean coupled mercury model, we studied the significances of two processes, soil emission and atmospheric oxidation-reduction, in the global biogeochemical cycling of mercury and their parametrization to improve model performance. Implementing an empirical equation for soil emission flux (Esoil) including soil mercury concentration, solar radiation, and surface air temperature as parameters enabled the model to reproduce the observed seasonal variations of Esoil, whereas the default setting, which uses only the former two parameters, failed. The modified setting of Esoil also increased the model-simulated atmospheric concentration in the summertime surface layer of the lower- and midlatitudes and improved the model reproducibility for the observations in Japan and U.S. in the same period. Implementing oxidation of atmospheric gaseous elemental mercury (Hg(0)) by ozone with an updated rate constant, as well as the oxidation by bromine atoms (Br) in the default setting, improved the model reproducibility for the dry deposition fluxes observed in Japan. This setting, however, failed to reproduce the observed seasonal variations of atmospheric concentrations in the Arctic sites due to the imbalance between oxidation and reduction, whereas the model with Br as the sole Hg(0) oxidant in the polar atmosphere could capture the variations.

  17. Comprehensive atmospheric modeling of reactive cyclic siloxanes and their oxidation products

    Science.gov (United States)

    Janechek, Nathan J.; Hansen, Kaj M.; Stanier, Charles O.

    2017-07-01

    Cyclic volatile methyl siloxanes (cVMSs) are important components in personal care products that transport and react in the atmosphere. Octamethylcyclotetrasiloxane (D4), decamethylcyclopentasiloxane (D5), dodecamethylcyclohexasiloxane (D6), and their gas-phase oxidation products have been incorporated into the Community Multiscale Air Quality (CMAQ) model. Gas-phase oxidation products, as the precursor to secondary organic aerosol from this compound class, were included to quantify the maximum potential for aerosol formation from gas-phase reactions with OH. Four 1-month periods were modeled to quantify typical concentrations, seasonal variability, spatial patterns, and vertical profiles. Typical model concentrations showed parent compounds were highly dependent on population density as cities had monthly averaged peak D5 concentrations up to 432 ng m-3. Peak oxidized D5 concentrations were significantly less, up to 9 ng m-3, and were located downwind of major urban areas. Model results were compared to available measurements and previous simulation results. Seasonal variation was analyzed and differences in seasonal influences were observed between urban and rural locations. Parent compound concentrations in urban and peri-urban locations were sensitive to transport factors, while parent compounds in rural areas and oxidized product concentrations were influenced by large-scale seasonal variability in OH.

  18. Comprehensive atmospheric modeling of reactive cyclic siloxanes and their oxidation products

    Directory of Open Access Journals (Sweden)

    N. J. Janechek

    2017-07-01

    Full Text Available Cyclic volatile methyl siloxanes (cVMSs are important components in personal care products that transport and react in the atmosphere. Octamethylcyclotetrasiloxane (D4, decamethylcyclopentasiloxane (D5, dodecamethylcyclohexasiloxane (D6, and their gas-phase oxidation products have been incorporated into the Community Multiscale Air Quality (CMAQ model. Gas-phase oxidation products, as the precursor to secondary organic aerosol from this compound class, were included to quantify the maximum potential for aerosol formation from gas-phase reactions with OH. Four 1-month periods were modeled to quantify typical concentrations, seasonal variability, spatial patterns, and vertical profiles. Typical model concentrations showed parent compounds were highly dependent on population density as cities had monthly averaged peak D5 concentrations up to 432 ng m−3. Peak oxidized D5 concentrations were significantly less, up to 9 ng m−3, and were located downwind of major urban areas. Model results were compared to available measurements and previous simulation results. Seasonal variation was analyzed and differences in seasonal influences were observed between urban and rural locations. Parent compound concentrations in urban and peri-urban locations were sensitive to transport factors, while parent compounds in rural areas and oxidized product concentrations were influenced by large-scale seasonal variability in OH.

  19. 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

    2016-07-07

    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.

  20. 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

    2009-03-01

    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. 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.

  1. Infrared Faraday Rotation Spectroscopy for Monitoring of the atmospheric oxidation capacity

    Science.gov (United States)

    Zhao, Weixiong; Wysocki, Gerard; Chen, Weidong; Fertein, Eric; Petitprez, Denis; Zhang, Weijun

    2010-05-01

    Hydroxyl (OH) free radical is a key oxidizing species in the Earth's atmosphere. Because of its high reactivity, interference-free high sensitivity in situ monitoring of OH represents a real challenge. Faraday rotation spectroscopy (FRS) takes advantage of the particular magneto-optic effect observed for paramagnetic species. When a longitudinal magnetic field is applied, the magnetic circular birefringence is observed in the vicinity of Zeeman splitted absorption lines, and the polarization axis of a linearly polarized light is rotated due to interaction with the sample. This makes FRS capable of enhancing the detection sensitivity and completely eliminating interference from the diamagnetic species in the atmosphere such as CO2 and H2O. For OH free radicals, the highest absorption line strength and the largest gJ value make the Q (1.5) double lines of the 2Π 3-2 (ν=1←0) state at 2.8 μm clearly the best choice for sensitive detection in the infrared region by FRS. In this paper we report on the development of an FRS instrument based on a DFB diode laser operating at 2.8 μm. The prototype instrument with an active optical pathlength of only 25 cm and a lock-in time constant of 300 ms, achieves a 1σ detection limit of 3.5×1010 radicals/cm3. Substantial improvements of the instrumental components are currently ongoing and will be reported in details. Based on the conservative estimates the detection sensitivity of ~107 radicals/cm3 can be attained which is suitable for high accuracy atmospheric chemistry studies in environmental photoreactor chambers and for direct measurement of total reaction rate of OH in the atmosphere under atmospheric pressure.

  2. A highly oxidized atmosphere-ocean system and oceanic molybdenum drawdown during the Paleoproterozoic

    Science.gov (United States)

    Goto, K. T.; Ito, T.; Suzuki, K.; Anbar, A. D.; Gordon, G. W.; Kashiwabara, T.; Takaya, Y.; Shimoda, G.; Nozaki, T.; Kiyokawa, S.; Tetteh, G. M.; Nyame, F. K.

    2014-12-01

    Multiple lines of evidence suggest that the first major oxidation of the atmosphere-ocean system occurred during the Paleoproterozoic. However, the course of this redox transition remains elusive. A number of large Mn deposits are distributed in Paleoproterozoic sedimentary successions. As Mn is a redox-sensitive element characterized by high redox potential, knowledge of the Mn cycle in Paleoproterozoic seawater may provide insight into redox evolution during this period. Here, we investigate the Mn cycle in Paleoproterozoic seawater based on the Re-Os and Mo isotope compositions, and the abundance of major and trace elements, in Mn-rich sedimentary rocks from the Nsuta deposit of the Birimian Supergroup, Ghana. The Mn ore is composed mainly of rhodochrosite and is distributed at the boundaries between sedimentary rocks and tholeiitic volcanic rocks. The Re-Os isochron age (2217 ± 100 Ma) we obtained was consistent with U-Pb zircon ages of the volcanic rocks. The manganophile elements, except for Mo, show no enrichment, which is similar to modern hydrothermal Mn oxides. The PAAS-normalized REE compositions show positive Ce anomaly, indicative of Ce enrichment due to the oxidation of Ce(III) by Mn(IV). These findings suggest that Mn ore formed from primary precipitation of Mn oxides from hydrothermal fluids as they were mixed with bottom seawater at ~2.2 Ga. Thus, the bottom seawater would have been sufficiently oxygenated for the precipitation of Mn oxides at ~2.2 Ga. The Nsuta ore samples exhibit slight Mo enrichment, but Mo/Mn ratios are orders of magnitude lower than those in modern hydrothermal Mn oxides. We also found that the Mo isotopes in the Nsuta ore are ~0.7‰ heavier than those in modern hydrothermal and hydrogenous Mn oxides. As Mo in hydrothermal Mn oxides is sourced primarily from seawater (Goto et al., in prep), these results may reflect smaller oceanic Mo inventory and heavier seawater Mo isotope composition at 2.2 Ga than those of present

  3. A Self-Validation Method for High-Temperature Thermocouples Under Oxidizing Atmospheres

    Science.gov (United States)

    Mokdad, S.; Failleau, G.; Deuzé, T.; Briaudeau, S.; Kozlova, O.; Sadli, M.

    2015-08-01

    Thermocouples are prone to significant drift in use particularly when they are exposed to high temperatures. Indeed, high-temperature exposure can affect the response of a thermocouple progressively by changing the structure of the thermoelements and inducing inhomogeneities. Moreover, an oxidizing atmosphere contributes to thermocouple drift by changing the chemical nature of the metallic wires by the effect of oxidation. In general, severe uncontrolled drift of thermocouples results from these combined influences. A periodic recalibration of the thermocouple can be performed, but sometimes it is not possible to remove the sensor out of the process. Self-validation methods for thermocouples provide a solution to avoid this drawback, but there are currently no high-temperature contact thermometers with self-validation capability at temperatures up to . LNE-Cnam has developed fixed-point devices integrated to the thermocouples consisting of machined alumina-based devices for operation under oxidizing atmospheres. These devices require small amounts of pure metals (typically less than 2 g). They are suitable for self-validation of high-temperature thermocouples up to . In this paper the construction and the characterization of these integrated fixed-point devices are described. The phase-transition plateaus of gold, nickel, and palladium, which enable coverage of the temperature range between and , are assessed with this self-validation technique. Results of measurements performed at LNE-Cnam with the integrated self-validation module at several levels of temperature will be presented. The performance of the devices are assessed and discussed, in terms of robustness and metrological characteristics. Uncertainty budgets are also proposed and detailed.

  4. Photolysis and OH-Initiated oxidation of glycolaldehyde under atmospheric conditions.

    Science.gov (United States)

    Magneron, I; Mellouki, A; Le Bras, G; Moortgat, G K; Horowitz, A; Wirtz, K

    2005-05-26

    The photolysis and OH-initiated oxidation of glycolaldehyde (HOCH(2)CHO), which are relevant atmospheric processes, have been investigated under different conditions using complementary methods in three different laboratories. The UV absorption cross sections of glycolaldehyde determined in two of the laboratories are in excellent agreement. The photolysis of glycolaldehyde in air has been investigated in a quartz cell with sunlamps and in the EUPHORE chamber irradiated by sunlight. The mean photolysis rate measured under solar radiation was (1.1 +/- 0.3) x 10(-5) s(-1) corresponding to a mean effective photolysis quantum yield of (1.3 +/- 0.3). The major products detected were HCHO and CO, whereas CH(3)OH was also observed with an initial yield around 10%. Evidence for OH production was found in both experiments using either OH scavenger or OH tracer species. Photolysis of glycolaldehyde was used as the OH source to measure the reaction rate constants of OH with a series of dienes by the relative method and to identify and quantify the oxidation products of the OH-initiated oxidation of 2-propanol. The different experiments suggest that OH is produced by the primary channel: HOCH(2)CHO + hnu --> OH + CH(2)CHO (1). The rate constant of the OH reaction with glycolaldehyde has been measured at 298 K using the relative method: k(glyc) = (1.2 +/- 0.3) x 10(-11) cm(3) molecule(-1) s(-1). The product study of the OH-initiated oxidation of glycolaldehyde in air has been performed using both a FEP bag and the EUPHORE chamber. HCHO was observed to be the major product with a primary yield of around 65%. Glyoxal (CHOCHO) was also observed in EUPHORE with a primary yield of (22 +/- 6)%. This yield corresponds to the branching ratio ( approximately 20%) of the H-atom abstraction channel from the CH(2) group in the OH + HOCH(2)CHO reaction, the major channel ( approximately 80%) being the H-atom abstraction from the carbonyl group. The data obtained in this work, especially the

  5. Electrolyte effects on aqueous atmospheric oxidation of sulphur dioxide by ozone

    Energy Technology Data Exchange (ETDEWEB)

    Lagrange, J.; Pallares, C.; Lagrange, P. [CNRS, Strasbourg (France)

    1994-07-01

    The kinetics of sulphur(IV) oxidation by ozone in an aqueous solution were studied in various supporting electrolytes (NaClO4, NaCl, NH4ClO4, Na2SO4), using the stopped flow method. The rare data in perchlorate medium (chosen as reference electrolyte) are empirically correlated by the following expression: r = -d(O3)/dt = K(O3)(S(IV))(H(+))(exp -1/2). For each supporting electrolyte studied, the rate constant varies linearly with the ionic strength. The value of the rate constant is extrapolated to zero ionic strength. The rate constants are shown to be higher mainly when ammonium chloride and sodium sulphate are added to the solution. The effect of temperature is studied between 13 and 28 C. The reaction rate is unaffected by the trace presence of metal ion (Mm(2+), Fe(2+), Cu(2+), Fe(3+), Cr(3+)). The rate of oxidation is dissolved SO2 by O3, in water droplets under atmospheric conditions, is calculated as a function of (H(+)) and compared to the oxidation by H2O2. At zero ionic strength the ozone reaction becomes faster than hydrogen peroxide reaction above -log (H(+)) = 4.70. This effect appears at higher H(+) concentration when the ionic strength increases (-log (H(+)) = 3 in 4 mol/L NaCl or 2 mol/L Na2SO4).

  6. Behaviour of metallic materials containing aluminium in a sulfurizing and slightly oxidizing atmosphere

    Energy Technology Data Exchange (ETDEWEB)

    Broc, M.; Fauvet, P.; Olivier, P.; Sannier, J.

    1987-03-01

    A 500 h corrosion test was carried out at 800/sup 0/C in a coal-gasification-type complex atmosphere. Two alloys with 4%-5% mass Al (Manaurite XA and Gilphy 37A) and two alloys low in aluminium (Alloy 800 H and Nicral DB) were considered. The influence of a pre-oxidation treatment on the 4% - 5% mass Al alloys was studied. In the absence of pre-oxidation the alloy Manaurite XA undergoes internal corrosion equivalent to that of the alloys low in aluminium. The alloy Gilphy 37A displays a superior corrosion resistance, which is attributed to more homogeneous distribution of the aluminium and hence more favourable conditions for the growth of a continuous layer of Al/sub 2/O/sub 3/. Pre-oxidation treatment can lead to antagonistic effects: protection of the material or an increase in its rate of corrosion. The treatment must, in fact, give rise to a protective superficial layer of moderate depth which will not deprive the matrix of too much of its aluminium; this latter condition is indispensable to the reconstitution of the corrosion resistance when faults appear in the superficial layer of Al/sub 2/O/sub 3/.

  7. Uncertain Henry's law constants compromise equilibrium partitioning calculations of atmospheric oxidation products

    Science.gov (United States)

    Wang, Chen; Yuan, Tiange; Wood, Stephen A.; Goss, Kai-Uwe; Li, Jingyi; Ying, Qi; Wania, Frank

    2017-06-01

    Gas-particle partitioning governs the distribution, removal, and transport of organic compounds in the atmosphere and the formation of secondary organic aerosol (SOA). The large variety of atmospheric species and their wide range of properties make predicting this partitioning equilibrium challenging. Here we expand on earlier work and predict gas-organic and gas-aqueous phase partitioning coefficients for 3414 atmospherically relevant molecules using COSMOtherm, SPARC Performs Automated Reasoning in Chemistry (SPARC), and poly-parameter linear free-energy relationships. The Master Chemical Mechanism generated the structures by oxidizing primary emitted volatile organic compounds. Predictions for gas-organic phase partitioning coefficients (KWIOM/G) by different methods are on average within 1 order of magnitude of each other, irrespective of the numbers of functional groups, except for predictions by COSMOtherm and SPARC for compounds with more than three functional groups, which have a slightly higher discrepancy. Discrepancies between predictions of gas-aqueous partitioning (KW/G) are much larger and increase with the number of functional groups in the molecule. In particular, COSMOtherm often predicts much lower KW/G for highly functionalized compounds than the other methods. While the quantum-chemistry-based COSMOtherm accounts for the influence of intra-molecular interactions on conformation, highly functionalized molecules likely fall outside of the applicability domain of the other techniques, which at least in part rely on empirical data for calibration. Further analysis suggests that atmospheric phase distribution calculations are sensitive to the partitioning coefficient estimation method, in particular to the estimated value of KW/G. The large uncertainty in KW/G predictions for highly functionalized organic compounds needs to be resolved to improve the quantitative treatment of SOA formation.

  8. Uncertain Henry's law constants compromise equilibrium partitioning calculations of atmospheric oxidation products

    Directory of Open Access Journals (Sweden)

    C. Wang

    2017-06-01

    Full Text Available Gas–particle partitioning governs the distribution, removal, and transport of organic compounds in the atmosphere and the formation of secondary organic aerosol (SOA. The large variety of atmospheric species and their wide range of properties make predicting this partitioning equilibrium challenging. Here we expand on earlier work and predict gas–organic and gas–aqueous phase partitioning coefficients for 3414 atmospherically relevant molecules using COSMOtherm, SPARC Performs Automated Reasoning in Chemistry (SPARC, and poly-parameter linear free-energy relationships. The Master Chemical Mechanism generated the structures by oxidizing primary emitted volatile organic compounds. Predictions for gas–organic phase partitioning coefficients (KWIOM/G by different methods are on average within 1 order of magnitude of each other, irrespective of the numbers of functional groups, except for predictions by COSMOtherm and SPARC for compounds with more than three functional groups, which have a slightly higher discrepancy. Discrepancies between predictions of gas–aqueous partitioning (KW/G are much larger and increase with the number of functional groups in the molecule. In particular, COSMOtherm often predicts much lower KW/G for highly functionalized compounds than the other methods. While the quantum-chemistry-based COSMOtherm accounts for the influence of intra-molecular interactions on conformation, highly functionalized molecules likely fall outside of the applicability domain of the other techniques, which at least in part rely on empirical data for calibration. Further analysis suggests that atmospheric phase distribution calculations are sensitive to the partitioning coefficient estimation method, in particular to the estimated value of KW/G. The large uncertainty in KW/G predictions for highly functionalized organic compounds needs to be resolved to improve the quantitative treatment of SOA formation.

  9. 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

    OpenAIRE

    Rezar, Vida; Levar, Alenka; Salobir, Janez

    2015-01-01

    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 /...

  10. Atmospheric oxidation chemistry and ozone production: Results from SHARP 2009 in Houston, Texas

    Science.gov (United States)

    Ren, Xinrong; van Duin, Diana; Cazorla, Maria; Chen, Shuang; Mao, Jingqiu; Zhang, Li; Brune, William H.; Flynn, James H.; Grossberg, Nicole; Lefer, Barry L.; Rappenglück, Bernhard; Wong, Kam W.; Tsai, Catalina; Stutz, Jochen; Dibb, Jack E.; Thomas Jobson, B.; Luke, Winston T.; Kelley, Paul

    2013-06-01

    Ozone (O3) and secondary fine particles come from the atmospheric oxidation chemistry that involves the hydroxyl radical (OH) and hydroperoxyl radical (HO2), which are together called HOx. Radical precursors such as nitrous acid (HONO) and formaldehyde (HCHO) significantly affect the HOx budget in urban environments. These chemical processes connect surface anthropogenic and natural emissions to local and regional air pollution. Using the data collected during the Study of Houston Atmospheric Radical Precursors (SHARP) in spring 2009, we examine atmospheric oxidation chemistry and O3 production in this polluted urban environment. A numerical box model with five different chemical mechanisms was used to simulate the oxidation processes and thus OH and HO2 in this study. In general, the model reproduced the measured OH and HO2 with all five chemical mechanisms producing similar levels of OH and HO2, although midday OH was overpredicted and nighttime OH and HO2 were underpredicted. The calculated HOx production was dominated by HONO photolysis in the early morning and by the photolysis of O3 and oxygenated volatile organic compounds (OVOCs) in the midday. On average, the daily HOx production rate was 24.6 ppbv d-1, of which 30% was from O3 photolysis, 22% from HONO photolysis, 15% from the photolysis of OVOCs (other than HCHO), 14% from HCHO photolysis, and 13% from O3 reactions with alkenes. The O3 production was sensitive to volatile organic compounds (VOCs) in the early morning but was sensitive to NOx for most of afternoon. This is similar to the behavior observed in two previous summertime studies in Houston: the Texas Air Quality Study in 2000 (TexAQS 2000) and the TexAQS II Radical and Aerosol Measurement Project in 2006 (TRAMP 2006). Ozone production in SHARP exhibits a longer NOx-sensitive period than TexAQS 2000 and TRAMP 2006, indicating that NOx control may be an efficient approach for the O3 control in springtime for Houston. Results from this study

  11. DMS atmospheric concentrations and sulphate aerosol indirect radiative forcing: a sensitivity study to the DMS source representation and oxidation

    Directory of Open Access Journals (Sweden)

    O. Boucher

    2003-01-01

    Full Text Available The global sulphur cycle has been simulated using a general circulation model with a focus on the source and oxidation of atmospheric dimethylsulphide (DMS. The sensitivity of atmospheric DMS to the oceanic DMS climatology, the parameterisation of the sea-air transfer and to the oxidant fields have been studied. The importance of additional oxidation pathways (by O3 in the gas- and aqueous-phases and by BrO in the gas phase not incorporated in global models has also been evaluated. While three different climatologies of the oceanic DMS concentration produce rather similar global DMS fluxes to the atmosphere at 24-27 Tg S yr -1, there are large differences in the spatial and seasonal distribution. The relative contributions of OH and NO3 radicals to DMS oxidation depends critically on which oxidant fields are prescribed in the model. Oxidation by O3 appears to be significant at high latitudes in both hemispheres. Oxidation by BrO could be significant even for BrO concentrations at sub-pptv levels in the marine boundary layer. The impact of such refinements on the DMS chemistry onto the indirect radiative forcing by anthropogenic sulphate aerosols is also discussed.

  12. Sensitivity of Oxygen Isotopes of Sulfate in Ice Cores to Past Changes in Atmospheric Oxidant Concentrations

    Science.gov (United States)

    Sofen, E. D.; Alexander, B.; Kunasek, S. A.; Mickley, L.; Murray, L. T.; Kaplan, J. O.

    2009-12-01

    The oxygen isotopic composition (Δ17O) of sulfate from ice cores allows for a quantitative assessment of the past oxidative capacity of the atmosphere, which has implications for the lifetime of pollutants (e.g. CO) and greenhouse gases (e.g. CH4), and changes in the sulfur budget on various timescales. Using Δ17O of sulfate measurements from the WAIS-Divide, Antarctica and Site-A, Greenland ice cores as constraints, we use the GEOS-Chem global three-dimensional chemical transport model to study changes in the concentrations of OH, O3, and H2O2 and their impact on sulfate Δ17O between the preindustrial and present-day. The Greenland ice core sulfate oxygen isotope observations are insensitive to changes in oxidant concentrations on the preindustrial-industrial timescale due to the rising importance of metal catalyzed S(IV) oxidation in mid- to high-northern latitudes resulting from anthropogenic metal emissions. The small change in Antarctic ice core sulfate Δ17O observations on this timescale is consistent with simultaneous increases in boundary layer O3 (32%) and H2O2 (49%) concentrations in the Southern Hemisphere, which have opposing effects on the sulfate O-isotope anomaly. Sulfate Δ17O is insensitive to the relatively small (-12%) decrease in Southern Hemisphere OH concentrations on this timescale due to the dominance of in-cloud versus gas-phase formation of sulfate in the mid-to-high southern latitudes. We find that the fraction of sulfate formed globally through gas-phase oxidation has not changed substantially between preindustrial and present times, however the total amount of sulfate formed in the gas-phase has nearly quadrupled due to rising anthropogenic emissions of sulfur dioxide. Measurements over a glacial-interglacial cycle from the Vostok core indicate dramatic changes in the Δ17O of sulfate on this timescale, which provide a strong constraint for glacial-era atmospheric chemistry modeling efforts. We will present preliminary results of

  13. 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

  14. 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.

  15. The optical constants of several atmospheric aerosol species - Ammonium sulfate, aluminum oxide, and sodium chloride

    Science.gov (United States)

    Toon, O. B.; Pollack, J. B.; Khare, B. N.

    1976-01-01

    An investigation is conducted of problems which are related to a use of measured optical constants in the simulation of the optical constants of real atmospheric aerosols. The techniques of measuring optical constants are discussed, taking into account transmission measurements through homogeneous and inhomogeneous materials, the immersion of a material in a liquid of a known refractive index, the consideration of the minimum deviation angle of prism measurement, the interference of multiply reflected light, reflectivity measurements, and aspects of mathematical analysis. Graphs show the real and the imaginary part of the refractive index as a function of wavelength for aluminum oxide, NaCl, and ammonium sulfate. Tables are provided for the dispersion parameters and the optical constants.

  16. Translation Effects in Fluorine Doped Tin Oxide Thin Film Properties by Atmospheric Pressure Chemical Vapour Deposition

    Directory of Open Access Journals (Sweden)

    Mohammad Afzaal

    2016-10-01

    Full Text Available In this work, the impact of translation rates in fluorine doped tin oxide (FTO thin films using atmospheric pressure chemical vapour deposition (APCVD were studied. We demonstrated that by adjusting the translation speeds of the susceptor, the growth rates of the FTO films varied and hence many of the film properties were modified. X-ray powder diffraction showed an increased preferred orientation along the (200 plane at higher translation rates, although with no actual change in the particle sizes. A reduction in dopant level resulted in decreased particle sizes and a much greater degree of (200 preferred orientation. For low dopant concentration levels, atomic force microscope (AFM studies showed a reduction in roughness (and lower optical haze with increased translation rate and decreased growth rates. Electrical measurements concluded that the resistivity, carrier concentration, and mobility of films were dependent on the level of fluorine dopant, the translation rate and hence the growth rates of the deposited films.

  17. Methyl hydroperoxide (CH3OOH in urban, suburban and rural atmosphere: ambient concentration, budget, and contribution to the atmospheric oxidizing capacity

    Directory of Open Access Journals (Sweden)

    Y. Zhao

    2012-10-01

    Full Text Available Methyl hydroperoxide (MHP, one of the most important organic peroxides in the atmosphere, contributes to the tropospheric oxidizing capacity either directly as an oxidant or indirectly as a free radical precursor. In this study we report measurements of MHP from seven field campaigns at urban, suburban and rural sites in China in winter 2007 and summer 2006/2007/2008. MHP was usually present in the order of several hundreds of pptv level, but the average mixing ratios have shown a wide range depending on the season and measuring site. Primary sources and sinks of MHP are investigated to understand the impact of meteorological and chemical parameters on the atmospheric MHP budget. The MHP/(MHP+H2O2 ratio is also presented here to examine different sensitivities of MHP and H2O2 to certain atmospheric processes. The diurnal cycle of MHP/(MHP+H2O2, which is out of phase with that of both H2O2 and MHP, could imply that MHP production is more sensitive to the ambient NO concentration, while H2O2 is more strongly influenced by the wet deposition and the subsequent aqueous chemistry. It is interesting to note that our observation at urban Beijing site in winter 2007 provides evidence for the occasional transport of MHP-containing air masses from the marine boundary layer to the continent. Furthermore, the contribution of MHP as an atmospheric oxidant to the oxidizing capacity of an air parcel is assessed based on the "Counter Species" concept.

  18. 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.

  19. Investigation of atmospheric particle-bound reactive oxidative species (ROS): Their sources, characterization, and measurement

    Science.gov (United States)

    Venkatachari, Prasanna

    The relationships between the observed ROS concentrations in the New York City PMTACS study and various other atmospheric indicator species such as O3, HOx radicals, organic carbon (OC), elemental carbon (EC) and secondary organic carbon (SOC), as well as the statistical significance of any observable correlations were explored. A statistically significant moderate positive correlation between the O3 and the ROS concentrations, that indicated the local intensity of photochemistry was a moderate factor affecting the formation of particulate ROS in the daytime atmosphere, was observed. The results of the comparison between ROS and HO x concentrations indicated the existence of, at best, a weak positive correlation. The lack of a more positive correlation of the particle-bound ROS, both with ozone as well as other gas phase oxidants, showed the decoupling of the particulate matter ROS from the gas phase oxidants. The comparison of ROS concentrations with OC, EC, and SOC concentrations revealed a statistically significant relationship (P-value generator was developed, that could deliver known exposures of ROS. It was seen that the system was generally stable with an average ROS generation capability of 5.6 nanomoles of equivalent H2O2/m3 of (aerosol+ozone) flow sampled. Additionally, the alpha-pinene-O3 oxidation chemical system, used in the ROS generator, was studied to elucidate the structures of reaction products using liquid chromatography-multiple stage mass spectrometry (LC/MSn). The classes of compounds identified based on their multiple stage-MS fragmentation patterns, mechanistic considerations of alpha-pinene-O 3 oxidation, and general fragmentation rules, of the products from this reaction system were highly oxygenated species, predominantly containing hydroperoxide and peroxide functional groups. The oxidant species observed were clearly stable for the 1-3 hrs that elapsed during aerosol collection and analysis, and probably for much longer, thus rendering

  20. Atmospheric cycles of nitrogen oxides and ammonia. [source strengths and destruction rates

    Science.gov (United States)

    Bottger, A.; Ehhalt, D. H.; Gravenhorst, G.

    1981-01-01

    The atmospheric cycles of nitrogenous trace compounds for the Northern and Southern Hemispheres are discussed. Source strengths and destruction rates for the nitrogen oxides: NO, NO2 and HNO3 -(NOX) and ammonia (NH3) are given as a function of latitude over continents and oceans. The global amounts of NOX-N and NH3-N produced annually in the period 1950 to 1975 (34 + 5 x one trillion g NOx-N/yr and 29 + or - 6 x one trillion g NH3-N/yr) are much less than previously assumed. Globally, natural and anthropogenic emissions are of similar magnitude. The NOx emission from anthropogenic sources is 1.5 times that from natural processes in the Northern Hemisphere, whereas in the Southern Hemisphere, it is a factor of 3 or 4 less. More than 80% of atmospheric ammonia seems to be derived from excrements of domestic animals, mostly by bulk deposition: 24 + or - 9 x one trillion g NO3 -N/yr and 21 + or - 9 x one trillion g NH4+-N/yr. Another fraction may be removed by absorption on vegetation and soils.

  1. Atmospheric fate of dichlorvos: photolysis and OH-initiated oxidation studies.

    Science.gov (United States)

    Feigenbrugel, V; Le Person, A; Le Calvé, S; Mellouki, A; Muñoz, A; Wirtz, K

    2006-02-01

    The OH-initiated oxidation of dichlorvos (a widely used insecticide) has been investigated under atmospheric conditions at the large outdoor European photoreactor (EUPHORE) in Valencia, Spain. The rate constant of OH reaction with dichlorvos, k, was measured by using a conventional relative rate technique where 1,3,5-trimethylbenzene (TMB) and cyclohexane were taken as references. With the use of the rate constants of 5.67 x 10(-11) and of 6.97 x 10(-12) cm3 molecule(-1) s(-1) for the reactions OH + TMB and OH + cyclohexane, respectively, the resulting value of the OH reaction rate constant with dichlorvos was derived to be k = (2.6 +/- 0.3) x 10(-11) cm3 molecule(-1) s(-1). The tropospheric lifetime of dichlorvos with respect to reaction with OH radical has been estimated to be around 11 h. The major carbon-containing products observed for the OH reaction with dichlorvos in air under sunlight condition were phosgene and carbon monoxide. The formation of a very stable toxic primary product such as phosgene associated with the relatively short lifetime of dichlorvos may make the use of this pesticide even more toxic for humans when released into the atmosphere.

  2. A Rapid Deposition of Fluorine Doped Zinc Oxide Using the Atmospheric Pressure Chemical Vapour Deposition Method

    Science.gov (United States)

    Najafi, Navid; Rozati, S. M.

    2018-03-01

    Fluorine-doped zinc oxide (FZO) (ZnO:F) thin films were manufactured by atmospheric pressure chemical vapor deposition (APCVD) on glass substrates using zinc acetate dihydrate [C4H6O4Zn·2H2O, ZnAc] and ammonium fluoride (NH4F) as the source of fluorine with deposition duration of only 120 s for each sample. The effects of different amounts of fluorine as the dopant on the structural, electrical and optical properties of FZO thin films were investigated. The results show a polycrystalline structure at higher temperatures compared to amorphous structure at lower temperatures. The x-ray diffraction patterns of the polycrystalline films were identified as a hexagonal wurtzite structure of zinc oxide (ZnO) with the (002) preferred orientation. Also, the sheet resistance decreased from 17.8 MΩ/□ to 28.9 KΩ/□ for temperatures 325°C to 450°C, respectively. In order to further decrease the sheet resistance of the undoped ZnO thin films, fluorine was added using NH4F as the precursor, and again a drastic change in sheet resistance of only 17.7 Ω/□ was obtained. Based on the field emission scanning electron microscopy images, the fluorine concentration in CVD source is an important factor affecting the grain size and modifies electrical parameters. Ultraviolet-visible measurements revealed reduction of transparency of the layers with increasing fluorine as the dopant.

  3. Ball lightning from atmospheric discharges via metal nanosphere oxidation: from soils, wood or metals.

    Science.gov (United States)

    Abrahamson, John

    2002-01-15

    The slow (diffusion-limited) oxidation of metal nanoparticles has previously been proposed as the mechanism for ball lightning energy release, and argued to be the result of a normal lightning strike on soil. Here this basic model of networked nanoparticles is detailed further, and extended to lightning strikes on metal structures, and also to the action of other storm-related discharges or man-made discharges. The basic model predicted the important properties of "average" observed ball lightning, and the extension in this paper also covers high-energy examples of ball lightning. Laboratory checks of the theory are described, and predictions given of what conditions are necessary for observing ball lightning in the laboratory. Key requirements of the model are a sheltered region near the strike foot and starting materials which can generate a metal vapour under intensive heating, including soil, wood or a metal structure. The evolution of hydrocarbons (often plastics) along with metal vapour can ensure the local survival of the metal vapour even in an oxidizing atmosphere. Subsequent condensation of this vapour to metallic nanoparticles in networks provides the coherence of a ball structure, which also releases light over an extended time. Also discussed is the passage of ball lightning through a sheet of building material, including glass, and its occasional charring of flesh on close contact.

  4. A Rapid Deposition of Fluorine Doped Zinc Oxide Using the Atmospheric Pressure Chemical Vapour Deposition Method

    Science.gov (United States)

    Najafi, Navid; Rozati, S. M.

    2017-12-01

    Fluorine-doped zinc oxide (FZO) (ZnO:F) thin films were manufactured by atmospheric pressure chemical vapor deposition (APCVD) on glass substrates using zinc acetate dihydrate [C4H6O4Zn·2H2O, ZnAc] and ammonium fluoride (NH4F) as the source of fluorine with deposition duration of only 120 s for each sample. The effects of different amounts of fluorine as the dopant on the structural, electrical and optical properties of FZO thin films were investigated. The results show a polycrystalline structure at higher temperatures compared to amorphous structure at lower temperatures. The x-ray diffraction patterns of the polycrystalline films were identified as a hexagonal wurtzite structure of zinc oxide (ZnO) with the (002) preferred orientation. Also, the sheet resistance decreased from 17.8 MΩ/□ to 28.9 KΩ/□ for temperatures 325°C to 450°C, respectively. In order to further decrease the sheet resistance of the undoped ZnO thin films, fluorine was added using NH4F as the precursor, and again a drastic change in sheet resistance of only 17.7 Ω/□ was obtained. Based on the field emission scanning electron microscopy images, the fluorine concentration in CVD source is an important factor affecting the grain size and modifies electrical parameters. Ultraviolet-visible measurements revealed reduction of transparency of the layers with increasing fluorine as the dopant.

  5. Oxidative modification and electrochemical inactivation of Escherichia coli upon cold atmospheric pressure plasma exposure.

    Directory of Open Access Journals (Sweden)

    Marlène Dezest

    Full Text Available Cold atmospheric pressure plasmas (CAPPs are known to have bactericidal effects but the mechanism of their interaction with microorganisms remains poorly understood. In this study the bacteria Escherichia coli were used as a model and were exposed to CAPPs. Different gas compositions, helium with or without adjunctions of nitrogen or oxygen, were used. Our results indicated that CAPP induced bacterial death at decontamination levels depend on the duration, post-treatment storage and the gas mixture composition used for the treatment. The plasma containing O2 in the feeding gas was the most aggressive and showed faster bactericidal effects. Structural modifications of treated bacteria were observed, especially significant was membrane leakage and morphological changes. Oxidative stress caused by plasma treatment led to significant damage of E. coli. Biochemical analyses of bacterial macromolecules indicated massive intracellular protein oxidation. However, reactive oxygen and nitrogen species (RONS are not the only actors involved in E. coli's death, electrical field and charged particles could play a significant role especially for He-O2 CAPP.

  6. Manganese-cerium oxide catalysts prepared by non-thermal plasma for NO oxidation: Effect of O2 in discharge atmosphere

    Science.gov (United States)

    Liu, Lu; Zheng, Chenghang; Wu, Shenghao; Gao, Xiang; Ni, Mingjiang; Cen, Kefa

    2017-09-01

    Non-thermal plasma with different O2 concentration in discharge atmosphere was applied to synthesize manganese and cerium mixed-oxides catalysts, which were compared in NO oxidation activity. Discharge atmosphere displayed a crucial influence on the performance of the catalysts prepared by plasma. Relatively low O2 concentration in discharge atmosphere allows synthesizing manganese-cerium oxides catalysts in a moderate environment and therefore is favorable for better physicochemical properties which lead to superior catalytic behavior. The best catalyst was obtained by treatment with 10% O2/N2 plasma and presented over 80% NO conversion in the temperature range of 275-325 °C, whereas catalyst prepared in pure O2 discharge atmosphere had the same activity with a catalyst prepared by calcinations. A correlation between the surface properties of the plasma prepared catalysts and its catalytic activity in NO oxidation is proposed. The amount of the surface adsorbed oxygen has an obvious linear correlation with the amount of Ce3+, the H2 consumption at low temperatures and the catalytic performance. The superior catalytic performance is mainly attributed to the stronger interaction between manganese oxides and ceria, and the formation of poorly crystallized Mn-O-Ce phase in the catalyst which resulted from the slow decomposition of nitrates and organics during plasma treatment. Catalysts prepared in relatively low O2 concentration have large specific surface area and is abundant in Ce3+ species and active oxygen species. The study suggests that plasma treatment with proper discharge gas components is a promising method to prepare effective manganese- cerium oxides catalyst for NO oxidation.

  7. By Product Synergy Analysis

    Science.gov (United States)

    2011-03-24

    AFB developed an environmental management system manual; the manual was prepared according to the ISO 14001 standard. The program is focused on...20 Design for Environment ...................................................................................20 ISO 14000 Series... ISO 14000 Framework ..................................................................................21 Figure 6. By Product Flow

  8. 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.

  9. By-products of the oxidation of 2,4-dichlorophenol formed during the treatment of waste waters; Subproductos de oxidacion del 2,4-diclorofenol formados durante el tratamiento de aguas residuales

    Energy Technology Data Exchange (ETDEWEB)

    Pardos, M.; Alfonso, M. A.; Ormad, P.; Ovelleiro, J. L. [Universidad de Zaragoza (Spain)

    2000-07-01

    Nowadays, new technologies for the elimination of toxic and persistent substances present in industrial processes wastewater are being developed. One of these technologies uses the Fenton's reactive (iron salts and hydrogen peroxide) and UV light. In this work, it has been made an study about by-products generated and their formation mechanism, when an oxidation treatment is apply to a synthetic sample of 2,4-dichlorophenol (2,4-DCP) in aquatic medium. During the treatment it is detected the aromatic ring dehalogenation, the formation of low molecular weight oxygenated organic compounds (aldehydes, alcohols, and acids) and an important decreasing of the toxicity. (Author) 15 refs.

  10. Catalytic Oxidation of Benzophenone Hydrazone with Alumina-supported KMnO{sub 4} under Oxygen Atmosphere

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Kang Hyeok; Ko, Kwang Youn [Ajou University, Suwon (Korea, Republic of)

    2006-02-15

    KMnO{sub 4}/alumina reagent, which is cheap and environmentally safe, can serve as a catalytic oxidant under O{sub 2} atmosphere for the oxidation of benzophenone hydrazone. To the best of our knowledge, the present works are the first example where KMnO{sub 4}/alumina reagent acts as a catalytic oxidant under O{sub 2} atmosphere. Diphenyldiazomethane (Ph{sub 2}CN{sub 2}) is widely used for the protection of carboxylic acids by conversion to their diphenylmethyl (dpm) esters since dpm group can be easily deprotected by mild acidic condition or hydrogenolysis, especially in the field of b-lactams and peptides. Diphenyldiazomethane has been prepared by the oxidation of benzophenone hydrazone with reagents such as active manganese dioxide, mercuric oxide, peracetic acid, iodosobenzene diacetate or OXONE. However, some methods suffer from a disadvantage such as toxic nature of reagent, strong oxidative conditions or incompatibility with certain functional groups. For example, OXONE may not be employed for the in situ protection of carboxylic acid containing sulfide group due to the possibility of the concomitant oxidation of sulfide group.

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

    Science.gov (United States)

    Spanos, Dimitrios; Tørngren, Mari Ann; Christensen, Mette; Baron, Caroline P

    2016-03-01

    The characteristics and the oxidative stability of pork steaks and of pork mince were investigated during 2, 5 and 7days of refrigerated storage using oxygen (O2) levels of 0%, 20%, 50% and 80% in modified atmosphere packaging (MAP). Steaks stored during 7days were not affected by an increase in O2 concentration, as revealed by lipid and protein oxidation markers. In contrast, the mince was characterised by an altered protein profile, loss of free thiol groups and increased protein oxidation, early during storage. The oxidative stability of pork mince was improved by using intermediate (50%) O2 MAP. The results show that fresh pork products are affected differently by the MAP O2 concentration and strongly indicate that optimisation of MAP based on the retail product type would be of considerable benefit to their oxidative stability. Copyright © 2015 Elsevier Ltd. All rights reserved.

  12. Lipid oxidation and color changes of goose meat stored under vacuum and modified atmosphere conditions.

    Science.gov (United States)

    Orkusz, A; Haraf, G; Okruszek, A; Werenska-Sudnik, M

    2017-03-01

    The objective of the work was to investigate the color and lipid oxidation changes of goose breast meat packaged in vacuum and modified atmosphere (MA) conditions consisting of 80% O2, 20% CO2, and stored in refrigerated conditions at 4°C. Color stability was monitored by determining total heme pigments concentration; relative concentration of myoglobin, oxymyoglobin, and metmyoglobin; parameters of color L*, a*, b*, and sensory evaluation of the surface color. Lipid stability was measured by determining thiobarbituric acid reactive substances (TBARS). The samples were examined in 24 h after slaughter (unpacked muscles) and on d 4, 7, 9, 11 of storage (muscles packed in vacuum and in MA). Through the time of storage, samples packed in MA had higher TBARS values in comparison to the meat packed in vacuum. For samples packed in two types of atmospheres, the total pigments concentration decreased gradually within 11 d of storage. It was observed that relative metmyoglobin concentration increased whereas relative oxymyoglobin concentration decreased in total heme pigments in the MA stored muscle. The relative concentration of all three myoglobin forms sample packed in vacuum remained unchanged. The color parameters (L*, a*, b*) did not change for 11 d of storage for the vacuum packed meat. The value of the color parameter a* decreased and the value of the color parameters L* and b* increased in the samples packaged in MA. The data prove that if you store goose meat in MA (consisting of 80% O2, 20% CO2) or vacuum, the unchanged surface color is preserved for 9 and 11 day, respectively.Vacuum appears to be a better method as regards the maintaining of lipid stability in goose meat. © 2016 Poultry Science Association Inc.

  13. Oxidative capacity of the Mexico City atmosphere – Part 2: A ROx radical cycling perspective

    Directory of Open Access Journals (Sweden)

    M. J. Molina

    2010-07-01

    Full Text Available A box model using measurements from the Mexico City Metropolitan Area study in the spring of 2003 (MCMA-2003 is presented to study oxidative capacity (our ability to predict OH radicals and ROx (ROx=OH+HO2+RO2+RO radical cycling in a polluted (i.e., very high NOx=NO+NO2 atmosphere. Model simulations were performed using the Master Chemical Mechanism (MCMv3.1 constrained with 10 min averaged measurements of major radical sources (i.e., HCHO, HONO, O3, CHOCHO, etc., radical sink precursors (i.e., NO, NO2, SO2, CO, and 102 volatile organic compounds (VOC, meteorological parameters (temperature, pressure, water vapor concentration, dilution, and photolysis frequencies. Modeled HOx (=OH+HO2 concentrations compare favorably with measured concentrations for most of the day; however, the model under-predicts the concentrations of radicals in the early morning. This "missing reactivity" is highest during peak photochemical activity, and is least visible in a direct comparison of HOx radical concentrations. We conclude that the most likely scenario to reconcile model predictions with observations is the existence of a currently unidentified additional source for RO2 radicals, in combination with an additional sink for HO2 radicals that does not form OH. The true uncertainty due to "missing reactivity" is apparent in parameters like chain length. We present a first attempt to calculate chain length rigorously i.e., we define two parameters that account for atmospheric complexity, and are based on (1 radical initiation, n(OH, and (2 radical termination, ω. We find very high values of n(OH in the early morning are incompatible with our current understanding of ROx termination routes. We also observe missing reactivity in the rate of ozone production (P(O3. For example, the integral amount of ozone produced could be under-predicted by a factor of two. We argue that this uncertainty is partly accounted for in lumped chemical codes that are optimized to

  14. Oxidative capacity of the Mexico City atmosphere - Part 2: A ROx radical cycling perspective

    Science.gov (United States)

    Sheehy, P. M.; Volkamer, R.; Molina, L. T.; Molina, M. J.

    2010-07-01

    A box model using measurements from the Mexico City Metropolitan Area study in the spring of 2003 (MCMA-2003) is presented to study oxidative capacity (our ability to predict OH radicals) and ROx (ROx=OH+HO2+RO2+RO) radical cycling in a polluted (i.e., very high NOx=NO+NO2) atmosphere. Model simulations were performed using the Master Chemical Mechanism (MCMv3.1) constrained with 10 min averaged measurements of major radical sources (i.e., HCHO, HONO, O3, CHOCHO, etc.), radical sink precursors (i.e., NO, NO2, SO2, CO, and 102 volatile organic compounds (VOC)), meteorological parameters (temperature, pressure, water vapor concentration, dilution), and photolysis frequencies. Modeled HOx (=OH+HO2) concentrations compare favorably with measured concentrations for most of the day; however, the model under-predicts the concentrations of radicals in the early morning. This "missing reactivity" is highest during peak photochemical activity, and is least visible in a direct comparison of HOx radical concentrations. We conclude that the most likely scenario to reconcile model predictions with observations is the existence of a currently unidentified additional source for RO2 radicals, in combination with an additional sink for HO2 radicals that does not form OH. The true uncertainty due to "missing reactivity" is apparent in parameters like chain length. We present a first attempt to calculate chain length rigorously i.e., we define two parameters that account for atmospheric complexity, and are based on (1) radical initiation, n(OH), and (2) radical termination, ω. We find very high values of n(OH) in the early morning are incompatible with our current understanding of ROx termination routes. We also observe missing reactivity in the rate of ozone production (P(O3)). For example, the integral amount of ozone produced could be under-predicted by a factor of two. We argue that this uncertainty is partly accounted for in lumped chemical codes that are optimized to predict

  15. Iohexol degradation in wastewater and urine by UV-based Advanced Oxidation Processes (AOPs): Process modeling and by-products identification.

    Science.gov (United States)

    Giannakis, Stefanos; Jovic, Milica; Gasilova, Natalia; Pastor Gelabert, Miquel; Schindelholz, Simon; Furbringer, Jean-Marie; Girault, Hubert; Pulgarin, César

    2017-06-15

    In this work, an Iodinated Contrast Medium (ICM), Iohexol, was subjected to treatment by 3 Advanced Oxidation Processes (AOPs) (UV, UV/H2O2, UV/H2O2/Fe(2+)). Water, wastewater and urine were spiked with Iohexol, in order to investigate the treatment efficiency of AOPs. A tri-level approach has been deployed to assess the UV-based AOPs efficacy. The treatment was heavily influenced by the UV transmittance and the organics content of the matrix, as dilution and acidification improved the degradation but iron/H2O2 increase only moderately. Furthermore, optimization of the treatment conditions, as well as modeling of the degradation was performed, by step-wise constructed quadratic or product models, and determination of the optimal operational regions was achieved through desirability functions. Finally, global chemical parameters (COD, TOC and UV-Vis absorbance) were followed in parallel with specific analyses to elucidate the degradation process of Iohexol by UV-based AOPs. Through HPLC/MS analysis the degradation pathway and the effects the operational parameters were monitored, thus attributing the pathways the respective modifications. The addition of iron in the UV/H2O2 process inflicted additional pathways beneficial for both Iohexol and organics removal from the matrix. Copyright © 2016 Elsevier Ltd. All rights reserved.

  16. Effect of ambient atmosphere in the annealing of indium tin oxide films

    Energy Technology Data Exchange (ETDEWEB)

    Steckl, A.J.; Mohammed, G.

    1980-07-01

    Isochronal annealing experiments on dc-sputtered indium tin oxide (ITO) films in inert (N/sub 2/), reducing (N/sub 2//H/sub 2/) and oxidizing atmospheres were cumulatively performed over the 50..-->..500..-->..50 /sup 0/C range. Three anneal regimes have been identified. In region I, T/sub A/=50..-->..200 /sup 0/C, crystallization occurs, resulting in a sharp drop in sheet resistance (R/sub s/) due to increasing mobility. T/sub A/approx. =200 /sup 0/C results in a minimum R/sub s/. In region II, 200..-->..500..-->..200 /sup 0/C, R/sub s/ is proportional to T/sub A/, increasing (decreasing) during the forward (reverse) anneal cycle. This behavior is apparently due to a temperature-dependent active oxygen concentration and its effect on the carrier concentration. In region III, 200..-->..50 /sup 0/C, R/sub s/ is constant with T/sub A/. Optical transmission and x-ray diffraction experiments were performed at 100 /sup 0/C intervals. Successive anneals tended to increase the transmission in the visible and near-UV regions and to decrease it in the near- and far-IR region. Strong evidence of the Burstein-Moss shift was observed and an extrapolated intrinsic band gap of 3.85 eV was determined. Free-carrier absorption over the 2--5-..mu..m regions was evident after the 200 /sup 0/C anneal for all ambients. From the x-ray data, no evidence of crystallinity was observed in the as-deposited case and for anneals up to 100 /sup 0/C. For anneals in the 300--500 /sup 0/C range, a grain size of the order of 600 A with an orientation normal to the (222) plane was observed for all ambients.

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

    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); Heft, A. [Innovent e.V. Technology Development, Department of Surface Engineering, Prüssingstr. 27B, 07745 Jena (Germany); Schäfer, P.; Haidu, F.; Lehmann, D. [Chemnitz University of Technology, Semiconductor Physics, Reichenhainer Str. 70, 09126 Chemnitz (Germany); Grünler, B.; Schimanski, A. [Innovent e.V. Technology Development, Department of Surface Engineering, Prüssingstr. 27B, 07745 Jena (Germany); Zahn, D.R.T. [Chemnitz University of Technology, Semiconductor Physics, Reichenhainer Str. 70, 09126 Chemnitz (Germany)

    2013-04-01

    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{sup −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{sup −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.

  18. 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 i......%) O2 MAP. The results show that fresh pork products are affected differently by the MAP O2 concentration and strongly indicate that optimisation of MAP based on the retail product type would be of considerable benefit to their oxidative stability....... in O2 concentration, as revealed by lipid and protein oxidation markers. In contrast, the mince was characterised by an altered protein profile, loss of free thiol groups and increased protein oxidation, early during storage. The oxidative stability of pork mince was improved by using intermediate (50......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...

  19. 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.

  20. 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

    2016-01-01

    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 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

  1. Microwave Spectroscopic Study of the Atmospheric Oxidation Product m-TOLUIC Acid and its Monohydrate

    Science.gov (United States)

    Al-Jabiri, Mohamad; Schnitzler, Elijah G.; Seifert, Nathan A.; Jäger, Wolfgang

    2017-06-01

    m-Toluic acid is a photo-oxidation product of m-xylene, a chemical byproduct of the oil and gas industry, and is a common component of secondary atmospheric aerosol. Organic acids, such as m-toluic acid, are also thought to play an important role in the initial steps of aerosol formation, which involves formation of hydrogen bonded clusters with molecular species, such as water, ammonia, and sulfuric acid. Somewhat surprisingly, the rotational spectrum of the m-toluic acid monomer has not been studied before. We have identified four stable conformers using ab initio calculations at the MP2/6-311++G(2df,2pd) level of theory. The two lowest energy conformers are rather close in energy and their rotational spectra were measured using a Balle-Flygare type microwave spectrometer. The structures and barriers to methyl internal rotation were determined. We have identified four isomers of the monohydrate of m-toluic acid using ab initio calculations. Measurements of the microwave spectra of the two lowest energy isomers are underway with a newly constructed chirped pulse microwave Fourier transform spectrometer in the frequency range from 2 to 6 GHz. The spectra and analyses will be presented.

  2. 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.

  3. 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

    2017-02-01

    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.

  4. Transport and deposition of nitrogen oxides and ozone in the atmospheric surface layer

    Science.gov (United States)

    Li, Yongxian

    Tropospheric ozone is an important photochemical air pollutant, which increases respiratory-related diseases, decreases crop yields, and causes other environmental problems. This research has focused on the measurement of soil biogenic emissions of nitric oxide (NO), one of the precursors for ozone formation, from intensively managed soils in the Southeast US, and examined the transport and deposition of NOx (NO + NO2) and ozone in the atmospheric surface layer, and the effects of NO emissions and its chemical reactions on ozone flux and deposition to the earth's surface. Emissions of nitric oxide were measured from an intensively managed agricultural soil, in the lower coastal plain of North Carolina (near Plymouth, NC), using a dynamic chamber technique. Measurements of soil NO emissions in several crop canopies were conducted at four different sites in North Carolina during late spring and summer of 1994-1996. The turbulent fluxes of NO2 and O3 at 5 m and 10 m above the ground were measured using the eddy-correlation technique near Plymouth, NC during late spring of 1995 and summer of 1996, concurrent with measurements of soil NO emissions using the dynamic chamber system. Soil NO emission from within the corn field was high averaging approximately 35 ng N/m2/s during the measurement period of 1995. In another study, vertical measurements of ozone were made on a 610 m tall tower located 15 km Southeast of Raleigh, NC during the summers of 1993-1997, as part of an effort by the State of North Carolina to develop a State Implementation Plan (SIP) for ozone control in the Raleigh Metropolitan Statistical Area. A strong correlation was observed between the nighttime and early morning ozone concentrations in the residual layer (CR) above the NBL and the maximum ground level concentration (C o max) the following afternoon. Based on this correlation, an empirical regression equation (Co max = 27.67*exp(0.016 CR)) was developed for predicting maximum ground level ozone

  5. Oxidation of the Martian surface - Constraints due to chemical processes in the atmosphere

    Science.gov (United States)

    Mcelroy, M. B.; Kong, T. Y.

    1976-01-01

    Dissociation of water in the Martian atmosphere may supply oxygen to the surface and may result in the formation of minerals such as goethite, as proposed by Huguenin. The supply rate is limited by chemical processes in the atmosphere which regulate the abundance of O2. The net surface sink for atmospheric oxygen can be as large as 33 million atoms per sq cm per sec which compares to the escape rate of 60 million atoms per sq cm per sec.

  6. Recent Advances in Atmospheric Vapor-Phase Deposition of Transparent and Conductive Zinc Oxide

    NARCIS (Netherlands)

    Illiberi, A.; Poodt, P.; Roozeboom, F.

    2014-01-01

    The industrial need for high-throughput and low-cost ZnO deposition processes has triggered the development of atmospheric vapor-phase deposition techniques which can be easily applied to continuous, in-line manufacturing. While atmospheric CVD is a mature technology, new processes for the growth of

  7. Climatic, tectonic, and biological factors affecting the oxidation state of the atmosphere and oceans: Implications for Phanerozoic O2 evolution

    Science.gov (United States)

    Ozaki, K.; Tajika, E.

    2015-12-01

    The Earth's atmosphere and oceans have seen fundamental changes in its oxidation state in response to the climatic, tectonic and geochemical variations. Over the past decade, several geochemical proxies have led to significant progress in understanding the paleredox states of ancient oceans. However, a quantitative interpretation of these data for atmospheric O2 levels remain unclear because the relationship between atmospheric O2 levels (pO2) and oceanic redox state depends on several environmental factors, such as terrestrial weathering rate, sea-level stands, and sinking rate of particulate organic matter (POM) in the water column and so on. It is widely thought that the redox-dependent P cycling also plays a crucial role in regulating pO2 because it acts as a negative feedback on a geological timescale. It is important that strength of this feedback for a given pO2 is also modulated by environmental factors, affecting not only O2 levels at steady state but also its susceptibility to environmental changes. In this study, a quantitative role of environmental factors in the oxidation state of Earth's surface environment is evaluated with an oceanic biogeochemical cycle model (CANOPS) coupled with global C cycle model, which enables us to understand the ancient CO2 and O2 evolution. Our results demonstrate that atmospheric O2 level at steady state is affected by CO2 input flux from Earth's interior via changes in biogeochemical cycles, but its response is modulated by several internal factors such as shelf area and POM sinking rate. We also found that early Paleozoic atmospheric O2 levels before the advent of land plant would be determined so that oceans may locate at the "edge of anoxia (EoA)" where the redox-dependency of marine P cycle plays a crucial role in regulating O2 cycle, and that POM sinking rate has a great impact on the EoA. Our findings provide insights into the O2 cycle over the Phanerozoic in response to the climatic and tectonic variations and

  8. Influence of modelled soil biogenic NO emissions on related trace gases and the atmospheric oxidizing capacity

    NARCIS (Netherlands)

    Steinkamp, J.; Ganzeveld, L.N.; Wilcke, W.; Lawrence, M.G.

    2009-01-01

    The emission of nitric oxide (NO) by soils (SNOx) is an important source of oxides of nitrogen (NOx=NO+NO2) in the troposphere, with estimates ranging from 4 to 21 Tg of nitrogen per year. Previous studies have examined the influence of SNOx on ozone (O-3) chemistry. We employ the ECHAM5/MESSy

  9. Soil carbon content and relative abundance of high affinity H2-oxidizing bacteria predict atmospheric H2 soil uptake activity better than soil microbial community composition

    NARCIS (Netherlands)

    Khdhiri, Mondher; Hesse, Laura; Popa, Maria Elena; Quiza, Liliana; Lalonde, Isabelle; Meredith, Laura K.; Röckmann, Thomas; Constant, Philippe

    2015-01-01

    Soil-atmosphere exchange of H2 is controlled by gas diffusion and the microbial production and oxidation activities in soil. Among these parameters, the H2 oxidation activity catalyzed by soil microorganisms harboring high affinity hydrogenase is the most difficult variable to parameterize because

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

    OpenAIRE

    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.

    2016-01-01

    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...

  11. Atmospheric Oxidation Mechanism and Kinetic Studies for OH and NO3 Radical-Initiated Reaction of Methyl Methacrylate

    Directory of Open Access Journals (Sweden)

    Rui Gao

    2014-03-01

    Full Text Available The mechanism for OH and NO3 radical-initiated oxidation reactions of methyl methacrylate (MMA was investigated by using density functional theory (DFT molecular orbital theory. Geometrical parameters of the reactants, intermediates, transition states, and products were fully optimized at the B3LYP/6-31G(d,p level. Detailed oxidation pathways were presented and discussed. The rate constants were deduced by the canonical variational transition-state (CVT theory with the small-curvature tunneling (SCT correction and the multichannel Rice-Ramspergere-Kassele-Marcus (RRKM theory, based on the potential energy surface profiles over the general atmospheric temperature range of 180–370 K. The calculated results were in reasonable agreement with experimental measurement.

  12. 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.

  13. 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...

  14. 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...

  15. Analysis of reaction products formed in the gas phase reaction of E,E-2,4-hexadienal with atmospheric oxidants: Reaction mechanisms and atmospheric implications

    Science.gov (United States)

    Colmenar, I.; Martin, P.; Cabañas, B.; Salgado, S.; Martinez, E.

    2018-03-01

    An analysis of reaction products for the reaction of E,E-2,4-hexadienal with chlorine atoms (Cl) and OH and NO3 radicals has been carried out at the first time with the aim of obtaining a better understanding of the tropospheric reactivity of α,β-unsaturated carbonyl compounds. Fourier Transform Infrared (FTIR) spectroscopy and Gas Chromatography-Mass Spectrometry with a Time of Flight detector (GC-TOFMS) were used to carry out the qualitative and/or quantitative analyses. Reaction products in gas and particulate phase were observed from the reactions of E,E-2,4- hexadienal with all oxidants. E/Z-Butenedial and maleic anhydride were the main products identified in gas phase. E-butenedial calculated molar yield ranging from 4 to 10%. A significant amount of multifunctional compounds (chloro and hydroxy carbonyls) was identified. These compounds could be formed in particulate phase explaining the ∼90% of unaccounted carbon in gas phase. The reaction with Cl atoms in the presence of NOx with a long reaction time gave Peroxy Acetyl Nitrate (PAN) as an additional product, which is known for being an important specie in the generation of the photochemical smog. Nitrated compounds were the major organic products from the reaction with the NO3 radical. Based on the identified products, the reaction mechanisms have been proposed. In these mechanisms a double bond addition of the atmospheric oxidant at C4/C5 of E,E-2,4-hexadienal is the first step for tropospheric degradation.

  16. Measurement and modeling of ozone and nitrogen oxides produced by laser breakdown in oxygen-nitrogen atmospheres.

    Science.gov (United States)

    Gornushkin, Igor B; Stevenson, Chris L; Galbács, Gábor; Smith, Ben W; Winefordner, James D

    2003-11-01

    The production of ozone nad nitrogen oxides was studied during multiple laser breakdown in oxygen-nitrogen mixtures at atmospheric pressure. About 2000 laser shots at 10(10) W cm-2 were delivered into a sealed reaction chamber. The chamber with a long capillary was designed to measure absorption of O3, NO, and NO2 as a function of the number of laser shots. The light source for absorption measurements was the continuum radiation emitted by the plasma during the first 0.2 microsecond of its evolution. A kinetic model was developed that encompassed the principal chemical reactions between the major atmospheric components and the products of laser breakdown. In the model, the laser plasma was treated as a source of nitric oxide and atomic oxygen, whose rates of production were calculated using measured absorption by NO, NO2, and O3. The calculated concentration profiles for NO, NO2, and O3 were in good agreement with measured profiles over a time scale of 0-200 s. The steady-state concentration of ozone was measured in a flow cell in air. For a single breakdown in air, the estimated steady-state yield of ozone was 2 x 10(12) molecules, which agreed with the model prediction. This study can be of importance for general understanding of laser plasma chemistry and for elucidating the nature of spectral interferences and matrix effects that may take place in applied spectrochemical analysis.

  17. Quantum chemical investigation on the mechanism and kinetics of OH radical-initiated atmospheric oxidation of PCB-47.

    Science.gov (United States)

    Sun, Yanhui; Zhang, Qingzhu; Wang, Hui; Wang, Wenxing

    2015-08-01

    The OH radical-initiated atmospheric oxidation degradation of 2,2',4,4'-tetrachlorobiphenyl (PCB-47) was investigated by using quantum chemical calculations. All possible pathways involved in the oxidation process were discussed. Potential barriers and reaction heats have been obtained to assess the energetically favorable reaction pathways and the relatively stable products. The study shows that the OH radicals are more likely to attack the C3 and C5 atom of the aromatic ring in the PCB-47 molecule to form PCB-OH adducts. Subsequent reactions are the addition of O2 or NO2 molecule to the PCB-OH adducts at the ortho position of the OH group. Water molecule plays an important role during the whole degradation process. The individual and overall rate constants were calculated by using the Rice-Ramsperger-Kassel-Marcus (RRKM) theory over the temperature range of 180-370K. At 298K, the atmospheric lifetime of PCB-47 determined by OH radicals is about 9.1d. The computational results are crucial to risk assessment and pollution prevention of PCBs. Copyright © 2015 Elsevier Ltd. All rights reserved.

  18. Single Particle Studies of Heterogeneous Atmospheric Chemistry on Aluminum Oxide Particles in a Quadrupole Trap

    Science.gov (United States)

    2000-03-01

    species of atmospheric importance are also available in permeation tubes, including S02, N02, NH3 , and many halocarbons. 3.5 Alumina Samples and Their...2) over a 20 cm optical path. A catalytic scrubber removes ozone from the reference beam path, and a four-way teflon valve interchanges scrubbed and

  19. The Great Oxidation of Earth's Atmosphere: Contesting the Yoyo Model Via Transition Stability Analysis

    Science.gov (United States)

    Cuntz, M.; Roy, D.; Musielak, Z. E.

    2009-11-01

    A significant controversy regarding the climate history of the Earth and its relationship to the development of complex life forms concerns the rise of oxygen in the early Earth's atmosphere. Geological records show that this rise occurred about 2.4 Gyr ago, when the atmospheric oxygen increased from less than 10-5 present atmospheric level (PAL) to more than 0.01 PAL and possibly above 0.1 PAL. However, there is a debate whether this rise happened relatively smoothly or with well-pronounced ups and downs (the Yoyo model). In our study, we explore a simplified atmospheric chemical system consisting of oxygen, methane, and carbon that is driven by the sudden decline of the net input of reductants to the surface as previously considered by Goldblatt et al. Based on the transition stability analysis for the system equations, constituting a set of non-autonomous and non-linear differential equations, as well as the inspection of the Lyapunov exponents, it is found that the equations do not exhibit chaotic behavior. In addition, the rise of oxygen occurs relative smoothly, possibly with minor bumps (within a factor of 1.2), but without major jumps. This result clearly argues against the Yoyo model in agreement with recent geological findings.

  20. 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 f...

  1. 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.

  2. Toluene decomposition performance and NOx by-product formation during a DBD-catalyst process.

    Science.gov (United States)

    Guo, Yufang; Liao, Xiaobin; Fu, Mingli; Huang, Haibao; Ye, Daiqi

    2015-02-01

    Characteristics of toluene decomposition and formation of nitrogen oxide (NOx) by-products were investigated in a dielectric barrier discharge (DBD) reactor with/without catalyst at room temperature and atmospheric pressure. Four kinds of metal oxides, i.e., manganese oxide (MnOx), iron oxide (FeOx), cobalt oxide (CoOx) and copper oxide (CuO), supported on Al2O3/nickel foam, were used as catalysts. It was found that introducing catalysts could improve toluene removal efficiency, promote decomposition of by-product ozone and enhance CO2 selectivity. In addition, NOx was suppressed with the decrease of specific energy density (SED) and the increase of humidity, gas flow rate and toluene concentration, or catalyst introduction. Among the four kinds of catalysts, the CuO catalyst showed the best performance in NOx suppression. The MnOx catalyst exhibited the lowest concentration of O3 and highest CO2 selectivity but the highest concentration of NOx. A possible pathway for NOx production in DBD was discussed. The contributions of oxygen active species and hydroxyl radicals are dominant in NOx suppression. Copyright © 2014. Published by Elsevier B.V.

  3. 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.

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

    NARCIS (Netherlands)

    Ganendra, G; De Muynck, W; Ho, A.; Hoefman, S.; De Vos, P.; Boeckx, P.; Boon, N.

    2014-01-01

    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 (similar to 20 % (v/v)) and low (similar to 100 ppmv) methane

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

    Science.gov (United States)

    Kühn, S.; Bibinov, N.; Gesche, R.; Awakowicz, P.

    2010-01-01

    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.

  6. High-Temperature Oxidation and Decarburization of 14.55 wt pct Cr-Cast Iron in Dry Air Atmosphere

    Science.gov (United States)

    Efremenko, V. G.; Chabak, Yu. G.; Lekatou, A.; Karantzalis, A. E.; Efremenko, A. V.

    2016-04-01

    The oxidation and decarburization behavior of 14.55 wt pct Cr-cast iron at 1273 K to 1423 K (1000 °C to 1150 °C) in a dry air atmosphere was studied. A gravimetric investigation showed that intensive oxidation of cast iron takes place at temperatures above 1273 K (1000 °C). It is found that oxidizing heating is accompanied by decarburization, which manifests itself in secondary and eutectic carbide dissolution. The volume fraction of carbides decreases with temperature and holding duration increasing. Decarburization results in the formation of a decarburized layer up to 4 mm in depth. A carbide-free layer in depth up to 100 μm appears in the free surface after 6 to 8 hours holding at 1373 K to 1423 K (1100 °C to 1150 °C). Preliminary activation energy calculations suggested that the eutectic carbide dissolution at the depths of 50 to 400 μm is controlled by carbon diffusion in austenite. The dissolution of eutectic carbides involves a capillarity-induced mechanism, which consists of formation and growth of capillary cavities inside carbides.

  7. A sub-atmospheric chemical vapor deposition process for deposition of oxide liner in high aspect ratio through silicon vias.

    Science.gov (United States)

    Lisker, Marco; Marschmeyer, Steffen; Kaynak, Mehmet; Tekin, Ibrahim

    2011-09-01

    The formation of a Through Silicon Via (TSV) includes a deep Si trench etching and the formation of an insulating layer along the high-aspect-ratio trench and the filling of a conductive material into the via hole. The isolation of the filling conductor from the silicon substrate becomes more important for higher frequencies due to the high coupling of the signal to the silicon. The importance of the oxide thickness on the via wall isolation can be verified using electromagnetic field simulators. To satisfy the needs on the Silicon dioxide deposition, a sub-atmospheric chemical vapor deposition (SA-CVD) process has been developed to deposit an isolation oxide to the walls of deep silicon trenches. The technique provides excellent step coverage of the 100 microm depth silicon trenches with the high aspect ratio of 20 and more. The developed technique allows covering the deep silicon trenches by oxide and makes the high isolation of TSVs from silicon substrate feasible which is the key factor for the performance of TSVs for mm-wave 3D packaging.

  8. 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.

  9. Treatment of a simulated textile wastewater containing the Reactive Orange 16 azo dye by a combination of ozonation and moving-bed biofilm reactor: evaluating the performance, toxicity, and oxidation by-products.

    Science.gov (United States)

    Castro, Francine D; Bassin, João Paulo; Dezotti, Márcia

    2017-03-01

    In this study, an aqueous solution containing the azo dye Reactive Orange 16 (RO16) was subjected to two sequential treatment processes, namely: ozonation and biological treatment in a moving-bed biofilm reactor (MBBR). The most appropriate ozonation pretreatment conditions for the biological process and the toxicity of the by-products resulting from RO16 ozone oxidation were evaluated. The results showed that more than 97 % of color removal from the dye solutions with RO16 concentrations ranging from 25 to 100 mg/L was observed in 5 min of ozone exposure. However, the maximum total organic carbon removal achieved by ozonation was only 48 %, indicating partial mineralization of the dye. Eleven intermediate organic compounds resulting from ozone treatment of RO16 solution were identified by LC/MS analyses at different contact times. The toxicity of the dye-containing solution decreased after 2 min of ozonation, but increased at longer contact times. The results further demonstrated that the ozonolysis products did not affect the performance of the subsequent MBBR, which achieved an average chemical oxygen demand (COD) and ammonium removal of 93 ± 1 and 97 ± 2 %, respectively. A second MBBR system fed with non-ozonated dye-containing wastewater was run in parallel for comparison purposes. This reactor also showed an appreciable COD (90 ± 1 %) and ammonium removal (97 ± 2 %), but was not effective in removing color, which remained practically invariable over the system. The use of short ozonation times (5 min) and a compact MBBR has shown to be effective for the treatment of the simulated textile wastewater containing the RO16 azo dye.

  10. Formation and occurrence of dimer esters of pinene oxidation products in atmospheric aerosols

    DEFF Research Database (Denmark)

    Kristensen, Kasper; Enggrob, Kirsten L.; King, S. M.

    2013-01-01

    products cis-pinic and terpenylic acids, but similar to the second-generation oxidation products 3-methyl-1,2,3-butane tricarboxylic acid (MBTCA) and diaterpenylic acid acetate (DTAA). Dimer esters were observed within the first 30 min, indicating rapid production simultaneous to their structural......The formation of carboxylic acids and dimer esters from alpha-pinene oxidation was investigated in a smog chamber and in ambient aerosol samples collected during the Biosphere Effects on Aerosols and Photochemistry Experiment (BEARPEX). Chamber experiments of alpha-pinene ozonolysis in dry air...... times higher during the warmer 2009 campaign relative to 2007, while the concentration of cis-pinic acid was approximately the same during both periods, and lack of correlation with levels of cis-pinic and terpenylic acids for both campaigns indicate that the formation of the pinyl-diaterpenyl ester...

  11. 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.

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

    Czech Academy of Sciences Publication Activity Database

    Hefny, M.M.; Pattyn, C.; Lukeš, Petr; Benedikt, J.

    2016-01-01

    Roč. 49, č. 40 (2016), s. 404002 ISSN 0022-3727 R&D Projects: GA MŠk(CZ) LD14080 Grant - others:European Cooperation in Science and Technology(XE) COST TD1208 Institutional support: RVO:61389021 Keywords : atmospheric pressure plasma * transport of reactive species * reactive oxygen species * aqueous phase chemistry * plasma and liquids * phenol aqueous chemistry Subject RIV: BL - Plasma and Gas Discharge Physics Impact factor: 2.588, year: 2016 http://iopscience.iop.org/article/10.1088/0022-3727/49/40/404002

  13. Improving Single-Chamber Solid Oxide Fuel Cell Performance by Plasma Treatment Using an Atmospheric-Pressure Helium Plasma Jet

    Science.gov (United States)

    Kanazawa, Seiji; Iwao, Tadasuke; Akamine, Shuichi; Ichiki, Ryuta

    2011-08-01

    An atmospheric-pressure helium plasma jet was used for the surface treatment of the electrodes in single-chamber solid oxide fuel cells (SC-SOFCs). The jet-type plasma source used in this study is suitable for the continuous and fine-area processing of materials, such as patterned electrodes. The basic plasma property was investigated by optical emission spectroscopy. Improvement in the performance of SC-SOFC was observed for the plasma-treated cell. From the scanning electron microscopy (SEM) observation, it was found that the surface morphology of the cell was largely changed. The increase in the area of the three-phase boundary among the electrode, electrolyte, and gas phase promoted electrochemical reactions. Under single-chamber operation condition at 850 °C, an open circuit voltage of 650 mV and a maximum power density of approximately 75 mW/cm2 were achieved for a coplanar-type cell.

  14. Flexible reduced graphene oxide supercapacitor fabricated using a nitrogen dc-pulse atmospheric-pressure plasma jet

    Science.gov (United States)

    Yang, Cheng-Han; Kuok, Fei-Hong; Liao, Chen-Yu; Wan, Ting-Hao; Chen, Chieh-Wen; Hsu, Cheng-Che; Cheng, I.-Chun; Chen, Jian-Zhang

    2017-02-01

    We use a nitrogen dc-pulse atmospheric-pressure plasma jet to fabricate a flexible reduced graphene oxide (rGO) supercapacitor with polyvinyl alcohol (PVA)/sulfuric acid (H2SO4) gel electrolyte. An areal capacitance of 47.03 mF · cm-2 (evaluated using cyclic voltammetry (CV) under a potential scan rate of 2 mV · s-1) is achieved. The supercapacitor can be operated without apparent degradation under bending with a bending radius of 0.55 cm. After a 1000 cycle CV stability test, the capacitance retention rate is 100% when flat and is 98.6% under bending (bending radius  =  0.55 cm), indicating promising stability of the APPJ-processed flexible supercapacitor.

  15. Characterization of atmospheric oxidants during, and after 2014 APEC summit: a case study of peroxides and ozone

    Science.gov (United States)

    Shen, H.; Chen, Z.; Huang, L.

    2016-12-01

    Peroxides and ozone (O3) are important atmospheric oxidants, and are directly related to the cycling of radicals in the atmosphere. They have a profound impact on many critical atmospheric chemical processes, and are closely associated with regional air pollution and global climate change. Many filed measurements have been conducted to study their concentrations, budget, and roles in the atmospheric chemistry in the past few decades. However, the characteristic and influencing factors of concentrations of peroxides and O3 are still not fully understood, especially in the polluted area. In this study, measurements for atmospheric peroxides and O3 were conducted simultaneously at PKU site in Beijing, China during, and after the 2014 Asia-Pacific Economic Cooperation (APEC) summit when strict pollution control measures were deployed. Hydrogen peroxide (H2O2) was the predominant peroxide observed, and occasionally, hydroxylmethyl hydroperoxide (HMHP) was detected. The average concentrations of H2O2 and O3 were 22.6±23.7pptv and 14.8±13.4ppbv, respectively. Both H2O2 and O3 showed distinct diurnal variations, with a peak between 14:00-16:00 for O3, and 18:00-20:00 for H2O2. However, the emergence of the H2O2 peak shifted to the night further both during, and after APEC compared to summer observations at the same site and in clean areas, but the exact mechanism is not clear. Concentrations of H2O2 and O3 were higher during APEC with A (After APEC)/D (During APEC) ratios of 0.3 and 0.7, respectively, contrary to the changes of most of the other observed trace constituents. We discussed the influencing factors in detail, and confirmed that the reduction of NOx was the decisive factors. Additionally, we found a sudden increase of concentrations of H2O2 and O3 on the early morning of 11 November. By analyzing the changes of related meteorological parameters, backward air mass trajectories, and pressure vertical velocity, we ascribed this to the downward transport of air

  16. Projections of atmospheric nitrous oxide under scenarios of improved agriculture and industrial efficiencies, diet modification, and representative concentration pathways (RCPs)

    Science.gov (United States)

    Davidson, E. A.

    2011-12-01

    Atmospheric concentrations of nitrous oxide (N2O), now at about 325ppb, have been increasing since the Industrial Revolution, as livestock herds increased globally and as use of synthetic-N fertilizers increased after WWII. The agricultural sector produces 70-80% of anthropogenic N2O. Significantly reducing those emissions while also improving the diets of the growing global human population will be very challenging. Increases in atmospheric N2O since 1860 are consistent with emissions factors of 2.5% of annual fertilizer-N usage and 2.0% of annual manure-N production being converted to N2O. These factors include both direct and indirect emissions attributable to these sources. Here I present projections of N2O emissions for a variety of scenarios including: (1) FAO population/diet scenarios with no changes in emission factors; (2) per-capita protein consumption in the developed world declines to 1980 levels by 2030 and only half of that is obtained from animal products, thus cutting global manure production by about 20%; (3) improvements in N-use efficiency and manure management reduce the emission factors by 50% by 2050; (4) same as 3 but industrial and transportation emissions are similarly reduced by 50% by 2050; and (5) all mitigations together. These projections are then compared to the four representative concentration pathways (RCPs) developed for the IPCC-AR5. With no further mitigation, the projections are consistent with RCP8.5, with atmospheric N2O at 368 ppb in 2050. RCP8.5 is a reasonable representation of N2O concentrations with growing agricultural production to feed a growing and better-nourished population, without improvements in agricultural efficiencies or changes in developed world diets. Major reductions in per-capita meat consumption in the developed world reduce projected 2050 N2O to 256 ppb, which is in line with RCP6.0. Cutting emission factors in half but without diet change would also lower projected 2050 N2O to 252ppb. Adding 50

  17. Ruthenium nanoparticles for oxygen reduction and/or hydrogen oxidation, prepared by pyrolysis in a reducing atmosphere

    Energy Technology Data Exchange (ETDEWEB)

    Altamirano-Gutierrez, A.; Villagran-Naredo, J.L.A.; Jimenez-Sandoval, O. [Inst. Politecnico Nacional (Mexico). Centro de Investigacion y de Estudios Avanzados; Hernandez-Castellanos, R. [Centro de Investigacion y Desarrollo Technologic en Electroquimica (Mexico)

    2006-07-01

    An investigation of the synthesis, structural and electrochemical characterization of ruthenium-based materials prepared by pyrolysis was presented. Ru{sub 3}(CO){sub 12} materials were pyrolized in a hydrogen atmosphere at 80, 140, 360 and 460 degrees C. The materials were then characterized using Fourier Transform Infrared (FTIR) spectroscopy; X-ray diffraction (XRD) and scanning electron microscopy (SEM). Oxygen reduction reactions (ORR) and hydrogen oxidation reactions (HOR) were evaluated through the use of rotating disk electrode measurements in a 0.5 M hydrogen peroxide (H{sub 2}SO{sub 4}) electrolyte at room temperature. Results of the investigation indicated that the Ru{sub 3}(CO){sub 12} precursor was completely decarbonylated in H{sub 2} at 140 degrees C. Carbonyl group bands were observed when the materials were prepared at 80 degrees C due to the formation of an inactive Ru cluster resulting from a structural rearrangement of the cluster. Polarization curves indicated that the materials prepared at 140 degrees C were able to perform the ORR and HOR in an acid medium similar to the medium present in proton exchange (PE) fuel cells. The electrokinetic parameters indicated that the exchange current densities were of the same order as platinum (Pt) current densities, and that the ORR occurred via 4 electrons due to the direct formation of water. Tafel slope values for the HOR suggested that the mechanism of the reaction was related to Herovsky/Volmer types. It was concluded that the use of a reductive atmosphere in the preparation process of ruthenium-based materials prevents the formation of undesirable ruthenium oxides. The nano-sized materials prepared during the experiment did not exhibit loss of their catalytic properties after being exposed to air for several weeks. 4 refs., 2 figs.

  18. 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. Copyright © 2013 Elsevier B.V. All rights reserved.

  19. 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

  20. Proposed reference models for nitrous oxide and methane in the middle atmosphere

    Science.gov (United States)

    Taylor, F. W.; Dudhia, A.; Rodgers, C. D.

    1989-01-01

    Data from the Stratospheric and Mesospheric Sounder (SAMS) on the Nimbus 7 satellite, for the period from Jan. 1979 - Dec. 1981, are used to prepare a reference model for the long-lived trace gases, methane and nitrous oxide, in the stratosphere. The model is presented in tabular form on seventeen pressure surfaces from 20 to 0.1 mb, in 10 degree latitude bins from 50S to 70N, and for each month of the year. The means by which the data quality and interannual variability, and some of the more interesting globally and seasonally variable features of the data are discussed briefly.

  1. Impact of partitioning and oxidative processing of PAH in fogs and clouds on atmospheric lifetimes of PAH

    Science.gov (United States)

    Eagar, Jershon Dale; Ervens, Barbara; Herckes, Pierre

    2017-07-01

    The importance of the atmospheric aqueous phase of fogs and clouds, for the processing and removal of polycyclic aromatic hydrocarbons (PAHs) is not well known. A multiphase model was developed to determine the fate and lifetime of PAHs in fogs and clouds for a limited set of daytime conditions. The model describes partitioning between three phases (aqueous, liquid organic, and gas), experimental and estimated (photo)oxidation rates. Using a limited set of microphysical and chemical input conditions, the loss rates of PAHs in the complex three-phase system are explored. At 25 °C, PAHs with two, three and four rings are predicted to be primarily in the gas phase (fraction in the gas phase xg > 90%) while five- and six-ring PAHs partition significantly into droplets with aqueous phase fractions of 1-6% and liquid organic phase fractions of 31-91%, respectively. The predicted atmospheric chemical lifetimes of PAHs in the presence of fog or cloud droplets (<8 h) are significantly shorter than literature predictions of PAH lifetimes due to wet and dry deposition (1-14 days and 5-15 months, respectively) and shorter than or equal to predicted lifetimes due to chemical reactions in the gas and organic particulate phases (1-300 h). Even though PAH solubilities are ≤4 × 10-2 g L-1, the results of the current study show that often the condensed phase of fog and cloud droplets cannot be neglected as a PAH sink.

  2. Temperature dependence of carbon kinetic isotope effect for the oxidation reaction of ethane by OH radicals under atmospherically relevant conditions

    Science.gov (United States)

    Piansawan, Tammarat; Saccon, Marina; Laumer, Werner; Gensch, Iulia; Kiendler-Scharr, Astrid

    2015-04-01

    Modeling of the global distribution of atmospheric ethane sources and sinks by using the 13C isotopic composition requires accurate knowledge of the carbon kinetic isotope effect (KIE) of its atmospheric removal reactions. The quantum mechanical prediction implies the necessity to elucidate the temperature dependence of KIE within atmospherically relevant temperature range by experiment. In this study, the KIE and its temperature dependence for ethane oxidation by OH radicals was investigated at ambient pressure in a temperature range of 243 K to 303 K. The chemical reactions were carried out in a 15 L PFE reaction chamber, suspended in a thermally controlled oven. The isotope ratios of the gas phase components during the course of the reactions were measured by Thermal Desorption -- Gas Chromatography -- Isotope Ratio Mass Spectrometry (TD-GC-IRMS). For each temperature, the KIE was derived from the temporal evolution of the concentration and stable carbon isotope ratio (δ13C) of ethane using a method adapted from the relative reaction rate concept. The room temperature KIE of the ethane reaction with OH radicals was found to be 6.85 ± 0.32 ‰. This value is in agreement with the previously reported value of 8.57 ± 1.95 ‰ [Anderson et al. 2004] but has a substantially lower uncertainty. The experimental results will be discussed with the KIE temperature dependence predicted by quantum mechanical calculations. Reference: Rebecca S. Anderson, Lin Huang, Richard Iannone, Alexandra E. Thompson, and Jochen Rudolph (2004), Carbon Kinetic Isotope Effects in the Gas Phase Reactions of Light Alkanes and Ethene with the OH Radical at 296 ± 4 K, J. Phys. Chem. A, 108, 11537--11544

  3. Thermal decomposition of wood in oxidizing atmosphere: A kinetic study from non-isothermal TG experiments

    Energy Technology Data Exchange (ETDEWEB)

    Cordero, T.; Rodriguez-Maroto, F.G.; Rodriguez, J.J. (Univ. of Malaga (Spain))

    1991-11-22

    The kinetics of thermal decomposition of four wood species in oxygen-bearing atmospheres of 5, 10 and 20% molar O{sub 2} concentrations have been studied from temperature-programmed experiments carried out at 5, 10 and 20 K min{sup {minus}1} heating rate. Devolatilization as well as combustion of the reamining solid have been considered to analyze the weight loss curves. The homogeneous volume reaction (VR) model has been used to describe devolatilization, whereas for solid combustion the grain model has been also checked. A two-stage approach has been used to fit the conversion-time curves and to derive the corresponding apparent kinetic parameters. The VR/VR (pyrolysis/combustion) combination provided a better description of the experimental {alpha}-t curves than the VR/grain combination. Holm oak and cork oak showed very close reactivities, whereas some differences were observed for aleppo pine and eucalyptus. 6 figs. 8 tabs., 20 refs.

  4. Recent changes in the oxidized to reduced nitrogen ratio in atmospheric precipitation

    Science.gov (United States)

    Kurzyca, Iwona; Frankowski, Marcin

    2017-10-01

    In this study, the characteristics of precipitation in terms of various nitrogen forms (NO3-, NO2-, NH4+, Norganic, Ntotal) is presented. The samples were collected in the areas of different anthropogenic pressure (urban area vs. ecologically protected woodland area, ∼30 km distant from each other; Wielkopolska region, Poland). Based on the Nox and Nred emission profiles (Nox/Nred ratio), temporal and spatial comparison was carried out. For both sites, during a decade of observation, more than 60% of samples had higher contribution of N-NH4+ than N-NO3-, the amount of N-NO2- was negligible, and organic nitrogen amounted to 30% of total nitrogen content which varied up to 16 mg/l. The precipitation events w ith high concentration of nitrogen species were investigated in terms of possible local and remote sources of nitrogen (synoptic meteorology), to indicate the areas which can act as potential sources of N-compounds. Based on the chemometric analysis, it was found that Nred implies Nox and vice versa, due to interactions between them in the atmosphere. Taking into account the analysis of precipitation occurring simultaneously in both locations (about 50% of all rainfall episodes), it was observed that such factor as anthropogenic pressure differentiates but does not determine the chemical composition of precipitation in the investigated areas (urban vs. woodland area; distance of ∼30 km). Thermodynamics of the atmosphere had a significant impact on concentrations of N-NO3- and N-NH4+ in precipitation, as well as the circulation of air masses and remote N sources responsible for transboundary inflow of pollutants.

  5. Rapid atmospheric pressure plasma jet processed reduced graphene oxide counter electrodes for dye-sensitized solar cells.

    Science.gov (United States)

    Liu, Hsiao-Wei; Liang, Sheng-Ping; Wu, Ting-Jui; Chang, Haoming; Kao, Peng-Kai; Hsu, Cheng-Che; Chen, Jian-Zhang; Chou, Pi-Tai; Cheng, I-Chun

    2014-09-10

    In this work, we present the use of reduced graphene oxide (rGO) as the counter electrode materials in dye-sensitized solar cells (DSSCs). rGO was first deposited on a fluorine-doped tin oxide glass substrate by screen-printing, followed by post-treatment to remove excessive organic additives. We investigated the effect of atmospheric pressure plasma jet (APPJ) treatment on the DSSC performance. A power conversion efficiency of 5.19% was reached when DSSCs with an rGO counter electrode were treated by APPJs in the ambient air for a few seconds. For comparison, it requires a conventional calcination process at 400 °C for 15 min to obtain comparable efficiency. Scanning electron micrographs show that the APPJ treatment modifies the rGO structure, which may reduce its conductivity in part but simultaneously greatly enhances its catalytic activity. Combined with the rapid removal of organic additives by the highly reactive APPJ, DSSCs with APPJ-treated rGO counter electrode show comparable efficiencies to furnace-calcined rGO counter electrodes with greatly reduced process time. This ultrashort process time renders an estimated energy consumption per unit area of 1.1 kJ/cm(2), which is only one-third of that consumed in a conventional furnace calcination process. This new methodology thus saves energy, cost, and time, which is greatly beneficial to future mass production.

  6. 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.

  7. Protective effect of atmospheric pressure plasma on oxidative stress-induced neuronal injuries: an in vitro study

    Science.gov (United States)

    Yan, Xu; Qiao, Yajun; Ouyang, Jiting; Jia, Mei; Li, Jiaxin; Yuan, Fang

    2017-03-01

    Atmospheric pressure plasma jet (APPJ) can produce biological active species for biomedical applications. This work proves direct evidence of the protective effects of APPJ against oxidative stress. SH-SY5Y cells, a commonly used cell model for the study of neurotoxicity and neuroprotection, were treated with APPJ for different durations. Then, cells were exposed to 200 µM H2O2 for 24 h and cell viability was measured using a CCK-8 kit. Changes in cell apoptosis were further confirmed by calcein-AM fluorescence imaging and flow cytometry. Extracellular NO production was detected using the Griess method. The results showed that APPJ protected SH-SY5Y from H2O2-induced apoptosis in a time-dependent manner. Moreover, extracellular NO production was significantly increased with the APPJ treatment. The results show in vitro that APPJ treatment could protect SH-SY5Y cells from oxidative stress by reducing cell apoptosis, which might be related to the reactive nitrogen species induced by the APPJ treatment. Our results indicate that the APPJ may have therapeutic potential as a novel ‘NO donor drug’ in neuroprotection and in the treatment of neurodegenerative diseases.

  8. Behaviors of trace elements in Neoarchean and Paleoproterozoic paleosols: Implications for atmospheric oxygen evolution and continental oxidative weathering

    Science.gov (United States)

    Murakami, Takashi; Matsuura, Kei; Kanzaki, Yoshiki

    2016-11-01

    The behaviors of redox-sensitive and/or bio-essential trace elements in Neoarchean and Paleoproterozoic paleosols (ancient weathering profiles) were investigated to better understand atmospheric oxygen evolution. The loss or retention of individual trace elements in the paleosols can show how continental oxidative weathering, and thus atmospheric oxygen evolution, took place against age mainly due to their various redox potentials. The V, Cr, Ni, Cu, Zn and Mo concentrations of two Paleoproterozoic paleosols were measured by inductively coupled plasma optical emission spectrometry and mass spectrometry, and those, as well as Co, W and U concentrations, of nine Neoarchean and Paleoproterozoic paleosols were obtained from the literature. The trace element behaviors were constrained by their degrees of loss or retention in the paleosols. We applied two methods to the estimation: (i) retention fraction of element M (a mass ratio of element M of paleosol to parent rock using immobile elements such as Ti) and (ii) element-element (in particular, Si-element) correlations at different profile depths of a paleosol. There are two distinct groups in trace element behavior in the Neoarchean and Paleoproterozoic paleosols: Co, Ni, Zn and W were lost from weathering profiles until the early Paleoproterozoic but retained in the middle and late Paleoproterozoic, while V, Cr, Cu, Mo and U were retained in the profiles until the early Paleoproterozoic or slightly later but lost from the profiles in the middle and late Paleoproterozoic. More precisely, the timings of such loss and retention were different between trace elements during the Paleoproterozoic. The characteristics of these changes from retention to loss or from loss to retention indicate that the changes occurred and lasted throughout the Paleoproterozoic. The trace element behaviors, accordingly, suggest that continental weathering became oxidative progressively with age during almost the whole Paleoproterozoic, and thus

  9. Evaluation of a full-scale wastewater treatment plant upgraded with ozonation and biological post-treatments: Abatement of micropollutants, formation of transformation products and oxidation by-products.

    Science.gov (United States)

    Bourgin, Marc; Beck, Birgit; Boehler, Marc; Borowska, Ewa; Fleiner, Julian; Salhi, Elisabeth; Teichler, Rebekka; von Gunten, Urs; Siegrist, Hansruedi; McArdell, Christa S

    2018-02-01

    To protect the ecosystem and drinking water resources in Switzerland and in the countries of the downstream catchments, a new Swiss water protection act entered into force in 2016 aiming to reduce the discharge of micropollutants from wastewater treatment plants (WWTPs). As a consequence, selected WWTPs must be upgraded by an advanced treatment for micropollutant abatement with suitable and economic options such as (powdered) activated carbon treatment or ozonation. WWTP Neugut (105'000 people equivalent) was the first WWTP in Switzerland to implement a long-term full-scale ozonation. Differing specific ozone doses in the range of 0.35-0.97 g O3/g DOC were applied to determine the adequate ozone dose to fulfill the requirements of the Swiss water protection act. Based on this assessment, a specific ozone dose of 0.55 g O3/g DOC is recommended at this plant to ensure an average abatement of the twelve selected indicator substances by ≥80% over the whole treatment. A monitoring of 550 substances confirmed that this dose was very efficient to abate a broad range of micropollutants by >79% on average. After ozonation, an additional biological post-treatment is required to eliminate possible negative ecotoxicological effects generated during ozonation caused by biodegradable ozonation transformation products (OTPs) and oxidation by-products (OBPs). Three biological treatments (sand filtration, moving bed, fixed bed) and granular activated carbon (GAC, fresh and pre-loaded) filtration were evaluated as post-treatments after ozonation. In parallel, a fresh GAC filter directly connected to the effluent of the secondary clarifier was assessed. Among the three purely biological post-treatments, the sand filtration performed best in terms of removal of dissolved organic carbon (DOC), assimilable organic carbon (AOC) and total suspended solids (TSS). The fresh activated carbon filtration ensured a significant additional micropollutants abatement after ozonation due to

  10. 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)).

  11. Release of iodine in the atmospheric oxidation of alkyl iodides and the fates of iodinated alkoxy radicals

    Science.gov (United States)

    Cotter, E. S. N.; Booth, N. J.; Canosa-Mas, C. E.; Wayne, R. P.

    This paper describes a study of the products of the Cl-atom-initiated oxidation of three alkyl iodides, RI=CH 3I, C 2H 5I, and 2-C 3H 7I, carried out in synthetic air at atmospheric pressure and at room temperature. Fourier-transform infrared spectroscopy was used to follow the decay of reactants and subsequent formation of products. The primary step proceeds via two channels, one of which yields HCl and an iodinated alkyl radical, and the other I atoms and an alkyl chloride. Quantitative analysis of the product yields, together with an assessment of the formation of HCl in secondary processes, allowed the fractional branching into the two channels to be calculated. The channel yielding HCl from RI constitutes a fraction 0.59, 0.93, and 0.68 for R=CH 3, C 2H 5, and 2-C 3H 7. The iodinated alkyl radical forms first a peroxy, and then an alkoxy, radical in the presence of air. The final products CH 2O, CH 3CHO, and CH 3COCH 3 were observed as expected for the decomposition of these radicals with RI=CH 3I, C 2H 5I, and 2-C 3H 7I, and the fractions of the alkoxy radicals fragmenting to the carbonyl compounds were 0.88, 0.57, and 0.86, respectively. Atomic iodine is formed concomitantly with the carbonyl species, so that these fractions also indicate the yield of I atoms in the secondary process. Alternative reaction pathways for the iodinated alkoxy radicals, in particular reaction with O 2, are evaluated and discussed. The yields of I atoms in the primary and secondary steps, taken in combination with kinetic data, make it possible to estimate the contribution of the Cl-initiated oxidation of the alkyl halides to I-atom production in the atmosphere (and, making certain assumptions, the analogous contribution from OH-initiated oxidation). Radical-initiated processes might augment the photolytic yield of I atoms from simple alkyl iodides: the maximum enhancements lie between 5% (CH 3I) and more than 30% (2-C 3H 7I).

  12. Formation and occurrence of dimer esters of pinene oxidation products in atmospheric aerosols

    Directory of Open Access Journals (Sweden)

    K. Kristensen

    2013-04-01

    Full Text Available The formation of carboxylic acids and dimer esters from α-pinene oxidation was investigated in a smog chamber and in ambient aerosol samples collected during the Biosphere Effects on Aerosols and Photochemistry Experiment (BEARPEX. Chamber experiments of α-pinene ozonolysis in dry air and at low NOx concentrations demonstrated formation of two dimer esters, pinyl-diaterpenyl (MW 358 and pinonyl-pinyl dimer ester (MW 368, under both low- and high-temperature conditions. Concentration levels of the pinyl-diaterpenyl dimer ester were lower than the assumed first-generation oxidation products cis-pinic and terpenylic acids, but similar to the second-generation oxidation products 3-methyl-1,2,3-butane tricarboxylic acid (MBTCA and diaterpenylic acid acetate (DTAA. Dimer esters were observed within the first 30 min, indicating rapid production simultaneous to their structural precursors. However, the sampling time resolution precluded conclusive evidence regarding formation from gas- or particle-phase processes. CCN activities of the particles formed in the smog chamber displayed a modest variation during the course of experiments, with κ values in the range 0.06–0.09 (derived at a supersaturation of 0.19%. The pinyl-diaterpenyl dimer ester was also observed in ambient aerosol samples collected above a ponderosa pine forest in the Sierra Nevada Mountains of California during two seasonally distinct field campaigns in September 2007 and July 2009. The pinonyl-pinyl ester was observed for the first time in ambient air during the 2009 campaign, and although present at much lower concentrations, it was correlated with the abundance of the pinyl-diaterpenyl ester, suggesting similarities in their formation. The maximum concentration of the pinyl-diaterpenyl ester was almost 10 times higher during the warmer 2009 campaign relative to 2007, while the concentration of cis-pinic acid was approximately the same during both periods, and lack of correlation

  13. The mechanism for enhanced oxidation degradation of dioxin-like PCBs (PCB-77) in the atmosphere by the solvation effect.

    Science.gov (United States)

    Xin, Mei-Ling; Yang, Jia-Wen; Li, Yu

    2017-07-11

    The reaction pathways of PCB-77 in the atmosphere with ·OH, O2, NO x , and (1)O2 were inferred based on density functional theory calculations with the 6-31G* basis set. The structures the reactants, transition states, intermediates, and products were optimized. The energy barriers and reaction heats were obtained to determine the energetically favorable reaction pathways. To study the solvation effect, the energy barriers and reaction rates for PCB-77 with different polar and nonpolar solvents (cyclohexane, benzene, carbon tetrachloride, chloroform, acetone, dichloromethane, ethanol, methanol, acetonitrile, dimethylsulfoxide, and water) were calculated. The results showed that ·OH preferentially added to the C5 atom of PCB-77, which has no Cl atom substituent, to generate the intermediate IM5. This intermediate subsequently reacted with O2 via pathway A to generate IM5a, with an energy barrier of 7.27 kcal/mol and total reaction rate of 8.45 × 10(-8) cm(3)/molecule s. Pathway B involved direct dehydrogenation of IM5 to produce the OH-PCBs intermediate IM5b, with an energy barrier of 28.49 kcal/mol and total reaction rate of 1.15 × 10(-5) cm(3)/molecule s. The most likely degradation pathway of PCB-77 in the atmosphere is pathway A to produce IM5a. The solvation effect results showed that cyclohexane, carbon tetrachloride, and benzene could reduce the reaction energy barrier of pathway A. Among these solvents, the solvation effect of benzene was the largest, and could reduce the total reaction energy barrier by 25%. Cyclohexane, carbon tetrachloride, benzene, dichloromethane, acetone, and ethanol could increase the total reaction rate of pathway A. The increase in the reaction rate of pathway A with benzene was 8%. The effect of solvents on oxidative degradation of PCB-77 in the atmosphere is important. Graphical abstract The reaction pathways of PCB-77 in the atmosphere with •OH, O2, NOx, and 1O2 were inferred based on density functional theory

  14. Cold Atmospheric Plasma Induces Apoptosis and Oxidative Stress Pathway Regulation in T-Lymphoblastoid Leukemia Cells

    Directory of Open Access Journals (Sweden)

    Eleonora Turrini

    2017-01-01

    Full Text Available Cold atmospheric plasma (CAP has shown its antitumor activity in both in vitro and in vivo systems. However, the mechanisms at the basis of CAP-cell interaction are not yet completely understood. The aim of this study is to investigate CAP proapoptotic effect and identify some of the molecular mechanisms triggered by CAP in human T-lymphoblastoid leukemia cells. CAP treatment was performed by means of a wand electrode DBD source driven by nanosecond high-voltage pulses under different operating conditions. The biological endpoints were assessed through flow cytometry and real-time PCR. CAP caused apoptosis in Jurkat cells mediated by p53 upregulation. To test the involvement of intrinsic and/or extrinsic pathway, the expression of Bax/Bcl-2 and caspase-8 was analyzed. The activation of caspase-8 and the upregulation of Bax and Bcl-2 were observed. Moreover, CAP treatment increased ROS intracellular level. The situation reverts after a longer time of treatment. This is probably due to compensatory cellular mechanisms such as the posttranscriptional upregulation of SOD1, CAT, and GSR2. According to ROS increase, CAP induced a significant increase in DNA damage at all treatment conditions. In conclusion, our results provide a deeper understanding of CAP potential in the oncological field and pose the basis for the evaluation of its toxicological profile.

  15. Do aerosols act as catalysts in the OH radical initiated atmospheric oxidation of volatile organic compounds?

    Science.gov (United States)

    Sørensen, M.; Hurley, M. D.; Wallington, T. J.; Dibble, T. S.; Nielsen, O. J.

    Smog chamber/FTIR techniques were used to study the relative reactivity of OH radicals with methanol, ethanol, phenol, C 2H 4, C 2H 2, and p-xylene in 750 Torr of air diluent at 296±2 K. Experiments were performed with, and without, 500-8000 μg m -3 (4000-50 000 μm 2 cm -3 surface area per volume) of NaCl, (NH 4) 2SO 4 or NH 4NO 3 aerosol. In contrast to the recent findings of Oh and Andino (Atmospheric Environment 34 (2000) 2901, 36 (2002) 149; International Journal of Chemical Kinetics 33 (2001) 422) there was no discernable effect of aerosol on the rate of loss of the organic compounds via reaction with OH radicals. Gas kinetic theory arguments cast doubt upon the findings of Oh and Andino. The available data suggest that the answer to the title question is "No". As part of this work the rate constants for reactions of OH radicals with methanol, ethanol, and phenol in 750 Torr of air at 296 K were determined to be: kOH+CH 3OH =(8.12±0.54)×10 -13, kOH+C 2H 5OH =(3.47±0.32)×10 -12 and kOH+phenol=(3.27±0.31)×10 -11 cm 3 molecule -1 s -1.

  16. 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

  17. 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...

  18. Laboratory oxygen isotopic study of sulfur (IV) oxidation: Origin of the mass‐independent oxygen isotopic anomaly in atmospheric sulfates and sulfate mineral deposits on Earth

    National Research Council Canada - National Science Library

    Savarino, Joël; Lee, Charles C. W; Thiemens, Mark H

    2000-01-01

    .... In the aqueous phase, sulfur oxidation by H 2 O 2 , O 3 , and O 2 , catalyzed by Fe(III) and Mn(II) were studied. In the gas phase we have investigated the only relevant reaction for the atmosphere...

  19. 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.

  20. Nanophase Iron Oxides as an Ultraviolet Sunscreen for Ancient Photosynthetic Microbes: A Possible Link Between Early Organisms, Banded-Iron Formations, and the Oxygenation of the Atmosphere

    Science.gov (United States)

    Bishop, Janice L.; Rothschild, Lynn J.; Rothschild, Lynn J.; Rogoff, Dana A.

    2006-01-01

    We propose that nanophase iron oxide-bearing materials provided important niches for ancient photosynthetic microbes on the early Earth that ultimately led to the oxygenation of the Earth s atmosphere and the formation of iron oxide deposits. Atmospheric oxygen and ozone attenuate UV radiation on the Earth today providing substantial protection for photosynthetic organisms. With ultraviolet radiation fluxes likely to have been even higher on the early Earth than today, accessing solar radiation was particularly risky for early organisms. Yet, we know that photosynthesis arose then and played a critical role in subsequent evolution. Of primary importance was protection at approx.250-290 nm, where peak nucleic acid (approx.260 nm) and protein (approx.280 nm) absorptions occur. Nanophase ferric oxide/oxyhydroxide minerals absorb, and thus block, the lethal UV radiation, while transmitting light through much of the visible and near-infrared regions of interest to photosynthesis (400 to 1100 nm). Further, they were available in early environments, and are synthesized by many organisms. Based on ferric oxide/oxyhydroxide spectral properties, likely geologic processes, and the results of experiments with the photosynthetic organisms, Euglena sp. and Chlumydomonus reinhardtii, we propose a scenario where photosynthesis, and ultimately the oxygenation of the atmosphere, depended on the protection of early microbes by nanophase ferric oxides/oxyhydroxides. The results of this study are also applicable to other potentially habitable iron-bearing planetary bodies because of the evolutionary pressure to utilize solar radiation when available as an energy source.

  1. Simultaneous detection of atmospheric nitrous oxide and carbon monoxide using a quantum cascade laser

    Science.gov (United States)

    Khan, Amir; Sun, Kang; Miller, David J.; Zondlo, Mark A.

    2011-06-01

    We describe a non-intrusive, open-path, fast-response compact sensor for simultaneous measurements of nitrous-oxide (N2O) and carbon-monoxide (CO) primarily designed for UAV applications. N2O is the third most important anthropogenic greenhouse gas, but the spatial and temporal distributions of N2O emissions are poorly quantified. On the other hand, CO is an important tracer to distinguish between fossil fuel and biogenic sources. We use a 4.5 micron thermoelectrically-cooled, distributed feedback, continuous wave quantum cascade laser as a mid-infrared radiation source to scan CO and N2O transitions centered at 4538.9 nm and 4539.8 nm respectively. Detection was achieved by a thermo-electrically (TE) cooled 5 micron Indium-Phosphide (InSb) infrared detector. For the first time in this application, a compact cylindrical cell with a pattern configuration to minimize the sensor size with a pathlength of 10 meters (2.54 cm radius mirrors, 25 cm basepath). Wavelength modulation spectroscopy was employed to achieve high sensitivity detection. The detection limit of 10-5 fractional absorbance was achieved at a 10 sec. averaging time. This is equivalent to less than 1 ppbv of N2O and 2 ppbv of CO out of 320 ppbv and 200 ppbv ambient levels respectively. In summary we report a cryogen-free, consumable-free sensor that can operate with 10s W of electrical power and packaged in a small shoe-box size which is ideal for UAV or airborne applications.

  2. Effect of flue gas composition on deposit induced high temperature corrosion under laboratory conditions mimicking biomass firing. Part I: Exposures in oxidizing and chlorinating atmospheres

    DEFF Research Database (Denmark)

    Okoro, Sunday Chukwudi; Kiamehr, Saeed; Montgomery, Melanie

    2017-01-01

    In biomass fired power plants, deposition of alkali chlorides on superheaters, aswell as the presence of corrosive flue gas species, give rise to fast corrosion ofsuperheaters. In order to understand the corrosion mechanism under thiscomplex condition, the influence of the flue gas composition...... bothoxidizing and oxidizing-chlorinating atmospheres, and the resulting corrosionproducts were comprehensively studied with scanning electron microscopy(SEM), energy dispersive X-ray spectroscopy (EDS), and X-ray diffraction (XRD)techniques. The results show that deposit-free samples suffer grain boundaryattack...... only in an oxidizing-chlorinating atmosphere, otherwise corrosionresults in formation of a duplex oxide. Corrosion attack on deposit-coatedsamples was higher than on deposit-free samples irrespective of the gaseousatmosphere. Specifically, severe volatilization of alloying elements occurred ondeposit...

  3. 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.

  4. The IPAC-NC field campaign: a pollution and oxidization pool in the lower atmosphere over Huabei, China

    Directory of Open Access Journals (Sweden)

    J. Z. Ma

    2012-05-01

    Full Text Available In the past decades, regional air pollution characterized by photochemical smog and grey haze-fog has become a severe environmental problem in China. To investigate this, a field measurement campaign was performed in the Huabei region, located between 32–42° N latitude in eastern China, during the period 2 April–16 May 2006 as part of the project "Influence of Pollution on Aerosols and Cloud Microphysics in North China" (IPAC-NC. It appeared that strong pollution emissions from urban and industrial centers tend to accumulate in the lower atmosphere over the central area of Huabei. We observed widespread, very high SO2 mixing ratios, about 20–40 ppbv at 0.5–1.5 km altitude and 10–30 ppbv at 1.5–3.0 km altitude. Average CO mixing ratios were 0.65–0.7 ppmv at 0.5–1.5 km altitude, and very high CO around 1 ppmv was observed during some flights, and even higher levels at the surface. We find the high pollution concentrations to be associated with enhanced levels of OH and HO2 radicals, calculated with a chemical box model constrained by the measurements. In the upper part of the boundary layer and in the lower free troposphere, high CO and SO2 compete with relatively less NO2 in reacting with OH, being efficiently recycled through HO2, preventing a net loss of HOx radicals. In addition to reactive hydrocarbons and CO, the oxidation of SO2 causes significant ozone production over Huabei (up to ~13% or 2.0 ppbv h−1 at 0.8 km altitude. Our results indicate that the lower atmosphere over Huabei is not only strongly polluted but also acts as an oxidation pool, with pollutants undergoing very active photochemistry over this part of China.

  5. 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.

  6. Multiphase composition changes and reactive oxygen species formation during limonene oxidation in the new Cambridge Atmospheric Simulation Chamber (CASC)

    Science.gov (United States)

    Gallimore, Peter J.; Mahon, Brendan M.; Wragg, Francis P. H.; Fuller, Stephen J.; Giorio, Chiara; Kourtchev, Ivan; Kalberer, Markus

    2017-08-01

    The chemical composition of organic aerosols influences their impacts on human health and the climate system. Aerosol formation from gas-to-particle conversion and in-particle reaction was studied for the oxidation of limonene in a new facility, the Cambridge Atmospheric Simulation Chamber (CASC). Health-relevant oxidising organic species produced during secondary organic aerosol (SOA) formation were quantified in real time using an Online Particle-bound Reactive Oxygen Species Instrument (OPROSI). Two categories of reactive oxygen species (ROS) were identified based on time series analysis: a short-lived component produced during precursor ozonolysis with a lifetime of the order of minutes, and a stable component that was long-lived on the experiment timescale (˜ 4 h). Individual organic species were monitored continuously over this time using Extractive Electrospray Ionisation (EESI) Mass Spectrometry (MS) for the particle phase and Proton Transfer Reaction (PTR) MS for the gas phase. Many first-generation oxidation products are unsaturated, and we observed multiphase aging via further ozonolysis reactions. Volatile products such as C9H14O (limonaketone) and C10H16O2 (limonaldehyde) were observed in the gas phase early in the experiment, before reacting again with ozone. Loss of C10H16O4 (7-hydroxy limononic acid) from the particle phase was surprisingly slow. A combination of reduced C = C reactivity and viscous particle formation (relative to other SOA systems) may explain this, and both scenarios were tested in the Pretty Good Aerosol Model (PG-AM). A range of characterisation measurements were also carried out to benchmark the chamber against existing facilities. This work demonstrates the utility of CASC, particularly for understanding the reactivity and health-relevant properties of organic aerosols using novel, highly time-resolved techniques.

  7. 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.

    2016-01-01

    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 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 studies, and by

  8. 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.

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

    Directory of Open Access Journals (Sweden)

    R. Volkamer

    2010-07-01

    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; the 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: Oxygenated VOC other than HCHO about 33%; HCHO and O3 photolysis each about 20%; O3/alkene reactions and HONO photolysis each about 12%, other sources <3%. Nitryl chloride photolysis could potentially contribute ~15% additional radicals, while NO2* + water makes – if any – a very small contribution (~2%. The peak radical production of ~7.5 107 molec cm−3 s−1 is

  10. The effect of the atmosphere on the optical properties of as-synthesized colloidal indium tin oxide

    Energy Technology Data Exchange (ETDEWEB)

    Capozzi, Charles J; Joshi, Salil; Gerhardt, Rosario A [School of Materials Science and Engineering, Georgia Institute of Technology, Atlanta, GA 30332-0245 (United States); Ivanov, Ilia N [Center for Nanophase Materials Sciences, Oak Ridge National Laboratory, One Bethel Valley Road, Oak Ridge, TN 37831-6488 (United States)], E-mail: rosario.gerhardt@mse.gatech.edu

    2009-04-08

    The optical properties of indium tin oxide (ITO) have often been explored when it is in the form of deposited thin films. In this study, a colloidal chemistry approach is taken to investigate the influence of the atmosphere on the optical properties of ITO nanoparticles. X-ray diffraction (XRD), transmission electron microscopy (TEM), absorption spectroscopy and photoluminescence (PL) were used to characterize colloidal ITO samples, synthesized under aerated and inert conditions, with the same composition. In both cases, the ITO can be completely dispersed in a non-polar solvent without any evidence of agglomeration. For the ITO made in air, the nanoparticle-solvent solution exhibits a pale green color, and XRD and TEM indicate an average particle size of {approx}7 nm and small shrinkage in the lattice structure. When the ITO is synthesized under inert conditions, the solution turns blue, and XRD and TEM indicate an average particle size of {approx}8 nm and even less strain in the lattice than for the ITO synthesized under aerated conditions. The change in color and lattice strain is attributed to the difference in oxygen vacancy concentration for the ITO nanoparticles synthesized under aerated and inert conditions, which exhibit different optical band gap values of 3.89 eV and 4.05 eV, respectively. Our work here shows that thin film deposition or sintering steps may not be required for studying the optical properties of as-synthesized ITO nanoparticles.

  11. 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.

  12. Integrated application of nitric oxide and modified atmosphere packaging to improve quality retention of button mushroom (Agaricus bisporus).

    Science.gov (United States)

    Jiang, Tianjia; Zheng, Xiaolin; Li, Jianrong; Jing, Guoxing; Cai, Luyun; Ying, Tiejin

    2011-06-15

    Button mushrooms (Agaricus bisporus) were dipped for 10min in different concentrations (0.5, 1, and 2mM) of 2,2'-(hydroxynitrosohydrazino)-bisethanamine (DETANO), a nitric oxide donor, then packed in biorientated polypropylene (BOPP) bags, heat sealed and stored at 4°C for 16days (d). Mushroom weight loss, firmness, colour, percent open caps, total phenolics, ascorbic acid and H2O2 contents, superoxide anion (O2(-)) production rate and activities of polyphenol oxidase (PPO), superoxide dismutase (SOD), catalase (CAT), and ascorbate peroxidase (APX) were measured. The results indicate that treatment with 1mM DETANO maintained a high level of firmness, delayed browning and cap opening, promoted the accumulation of phenolics, ascorbic acid and reduced the increases in both O2(-) production rate and H2O2 content. Furthermore, NO inhibited the activity of PPO, and increased the antioxidant enzymes activities of CAT, SOD and APX throughout storage period. Thus it was observed that application of NO in combination with modified atmosphere packaging (MAP) can extend the storage life of button mushroom up to 12d. Copyright © 2011 Elsevier Ltd. All rights reserved.

  13. High temperature cyclic oxidation of AISI 310 steel in atmospheres with variable oxidation content; Oxidacion ciclica de un acero refractario AISI 310 a alta temperatura en atmosferas con centenidos de oxigeno variables

    Energy Technology Data Exchange (ETDEWEB)

    Higuera-Hidalgo, V.; Belzunce-Varela, F. J.; Riba-Lopez, J.

    2005-07-01

    High temperature oxidation test of an AISI 310 stainless steel was performed in two different environments: in an standard atmosphere (21% oxygen) at 704, 800, 884 and 1,000 degree centigree and in the typical environment of a gas turbine and vapor generator of a combined-cycle electric generation unit (10%oxygen) at 800 and 1,000 degree centigree. The oxidation kinetics was determined by means of the measurements of the weight gain per unit surface of the specimen and also determining the thickness of the oxide layer. Comparable results have been obtained using both methodologies and the effect of the oxygen content along with the other experimental differences were determined observing the oxidation kinetics in both environments. The cyclic oxidation of AISI 310 deteriorates at temperatures higher than 1,000 degree centigree. (Author) 9 refs.

  14. Influence of Gas Atmosphere Dew Point on the Selective Oxidation and the Reactive Wetting During Hot Dip Galvanizing of CMnSi TRIP Steel

    Science.gov (United States)

    Cho, Lawrence; Lee, Seok Jae; Kim, Myung Soo; Kim, Young Ha; De Cooman, Bruno C.

    2013-01-01

    The selective oxidation and reactive wetting of intercritically annealed Si-bearing CMnSi transformation-induced plasticity steels were investigated by high-resolution transmission electron microscopy. In a N2 + 10 pct H2 gas atmosphere with a dew point (DP) ranging from 213 K to 278 K (-60 °C to 5 °C), a continuous layer of selective oxides was formed on the surface. Annealing in a higher DP gas atmosphere resulted in a thinner layer of external oxidation and a greater depth of internal oxidation. The hot dipping was carried out in a Zn bath containing 0.22 mass pct Al, and the bath temperature was 733 K (460 °C). Coarse and discontinuous Fe2Al5- x Zn x grains and Fe-Zn intermetallics (ζ and δ) were observed at the steel/coating interface after the hot dip galvanizing (HDG) of panels were annealed in a low DP atmosphere 213 K (-60 °C). The Fe-Zn intermetallics were formed both in areas where the Fe2Al5- x Zn x inhibition layer had not been formed and on top of non-stoichiometric Fe-Al-Zn crystals. Poor wetting was observed on panels annealed in a low DP atmosphere because of the formation of thick film-type oxides on the surface. After annealing in higher DP gas atmospheres, i.e., 263 K and 278 K (-10 °C and 5 °C), a continuous and fine-grained Fe2Al5- x Zn x layer was formed. No Fe-Zn intermetallics were formed. The small grain size of the inhibition layer was attributed to the nucleation of the Fe2Al5- x Zn x grains on small ferrite sub-surface grains and the presence of granular surface oxides. A high DP atmosphere can therefore significantly contribute to the decrease of Zn-coating defects on CMnSi TRIP steels processed in HDG lines.

  15. Physicochemical properties, lipid oxidation and sensory attributes of pork patties with lupin protein concentrate stored in vacuum, modified atmosphere and frozen state.

    Science.gov (United States)

    Danowska-Oziewicz, Marzena; Kurp, Lidia

    2017-09-01

    The effect of lupin protein concentrate (LPC) addition on selected physicochemical properties, lipid oxidation and sensory quality of pork patties was investigated. LPC was added at the level 1%, 2% and 3%. Patties were packed in vacuum and modified atmosphere (MA) and stored 42days in a refrigerator while aerobically packed patties were stored 84days in a frozen state. Patties with LPC showed a lower cooking loss, were less cohesive and juicy, and demonstrated a non-typical flavour compared to the control samples. The inhibitory effect of LPC on lipid oxidation was observed after cooking. During storage this effect was noted mainly in patties with 2% and 3% of LPC stored in frozen state while in vacuum- and MA-stored products it was demonstrated only at some measuring points. After 42days of storage only sample with 3% LPC packed in modified atmosphere was scored below the borderline of overall acceptance. Copyright © 2017 Elsevier Ltd. All rights reserved.

  16. 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

  17. 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

    2016-04-01

    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 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 (< 0.1 % or high OHRext ( ≥  100 s−1 in OFR185 and > 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

  18. 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.

  19. Effects of Dietary Rape Seed Oil, Copper(II) Sulphate and Vitamin E on Drip Loss, Colour and Lipid Oxidation of Chilled Pork Chops Packed in Atmospheric Air or in a High Oxygen Atmosphere.

    Science.gov (United States)

    Jensen, C; Flensted-Jensen, M; Skibsted, L H; Bertelsen, G

    1998-10-01

    The effect of addition of rapeseed oil (canola), CuSO(4) and vitamin E (all-rac-α-tocopheryl acetate) to pig diets on pork meat quality (lipid oxidation, colour and drip loss) was studied. Pigs were reared on ten different diets, either a control diet (no supplementation of rapeseed oil, CuSO(4) or vitamin E) or 6% rapeseed oil diets supplemented with CuSO(4) (0, 35 or 175mg/kg) and vitamin E (0, 100 or 200mg all-rac-α-tocopheryl acetate/kg). The natural content of vitamin E originating from feed ingredients amounted to 9-23mg vitamin E (α-tocopherol) per kg feed. Muscle vitamin E levels reflected the dietary intake and pigs fed the control diet had significantly lower levels than pigs fed rapeseed oil diets. The quality of fresh pork chops packed in air or in 80% O(2):20% CO(2) was followed during chill storage for 8 and 13 days, respectively. Colour, as measured by tristimulus colorimetry of pork chops packed in 80% oxygen atmosphere, was significantly improved with respect to redness when compared to chops packed in air, regardless of dietary treatment. The low vitamin E content in pigs fed the control feed significantly decreased a values and the oxidative stability of pork chops during chill storage compared to the other feeding groups. Packing of chops in a high-oxygen atmosphere increased lipid oxidation, especially in chops with low levels of vitamin E. Supplementation of rapeseed oil diets with 100 or 200mg vitamin E significantly decreased lipid oxidation of chill stored chops. Supplementation with CuSO(4) did not influence meat quality attributes (drip loss, colour stability and lipid oxidation) for any of the storage conditions.

  20. Waste/By-Product Hydrogen

    Science.gov (United States)

    2011-01-13

    Biogas , including anaerobic digester gas, can be reformed to produce hydrogen and used in a fuel cell to produce significant amounts of electricity...Waste/By product Hydrogen Waste H2 sources include: � Waste bio‐mass: biogas to high temp fuel cells to produce H2 – there are over two dozen sites...and heat. � When biogas is produced and used on‐site in a fuel cell, fuel utilization or overall energy efficiency can reach 90% and can reduce

  1. Studies in Atmospheric Chemistry. I. Assessing Exposure to Environmental Tobacco Smoke. I. Sulfur Oxides Chemistry Related to PM(10) Formation and Visibility Degradation

    Science.gov (United States)

    Caka, Fern M.

    I. Data from four DC-10 flights and forty-eight DC-9 flights are used to evaluate a model which predicts concentrations of ETS onboard commercial aircraft. A first order rate of penetration (decay) is shown to predict concentrations well. II. Two studies were conducted in Utah Valley and the Grand Canyon region. Annular diffusion denuders, impingers and real-time instruments were used to collect and measure sulfur oxide and nitrogen oxide species, ammonia, particulate acidity, and various oxidants. The data provided information on the distribution between gas and particulate phase species as a function of time, location and meteorology. Trends in the data sets which shed light on the factors which may contribute to atmospheric particulate conversion and the effect on PM_{10} formation and visibility degradation are presented.

  2. Application of a Chemiluminescence Detector for the Measurement of Total Oxides of Nitrogen and Ammonia in the Atmosphere

    Science.gov (United States)

    Hodgeson, J. A.; Bell, J. P.; Rehme, K. A.; Krost, K. J.; Stevens, R. K.

    1971-01-01

    By means of the thermal conversion of nitrogen dioxide to the nitric oxide, the chemiluminescent nitric oxide monitor, based on the nitric oxide plus ozone reaction, may be used for monitoring nitrogen dioxide plus nitric oxide (NO(x)). Under conditions previously described, ammonia is also converted to nitric oxide and therefore interferes. A metal surface, gold wool or stainless steel, operated at two different temperatures has been used to convert only nitrogen dioxide or nitrogen dioxide plus ammonia. Quantitative conversion of nitrogen dioxide to nitric oxide has been obtained at temperatures as low as 200 C. Conversion of ammonia is effected at temperatures of 300 C or higher. By the addition of a converter the basic nitric oxide monitor may be used for measuring NO(x) or NO(x) plus ammonia. As an alternate mode, for a fixed high temperature, a specific scrubber is described for removing NH3 without affecting NO2 concentrations.

  3. 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

  4. 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.

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

    Directory of Open Access Journals (Sweden)

    Gerard Masdeu

    2016-09-01

    Full Text Available 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. 1H and 13C NMR full characterization of the products was obtained based on 2D NMR, 1D selective NOESY and diffusion spectroscopy (DOSY experiments.

  6. Effects of antioxidant mixtures in the diet of finishing pigs on the oxidative status and shelf life of longissimus dorsi muscle packaged under modified atmosphere.

    Science.gov (United States)

    Rossi, R; Stella, S; Ratti, S; Maghin, F; Tirloni, E; Corino, C

    2017-11-01

    The effect of pig dietary supplementation with an antioxidant mixture (AOX), containing vitamin E and verbascoside, on animal oxidative status, meat quality parameters, and shelf life of the longissimus dorsi (LD) muscle was examined. Seventy pigs with an average live weight of 95.2 ± 1.2 kg were selected and assigned to 2 dietary treatments. The control (CTR) group was fed a commercial diet, and the AOX group was fed the same diet supplemented with the AOX, containing vitamin E and verbascoside from Verbenaceae extract, for 45 d before slaughter. At the beginning and at the end of the trial, blood samples were collected to determine oxidative status, using the Kit Radicaux Libres test. At slaughter, carcass weight was recorded and LD muscles from 10 pigs per treatment were sampled. Physical, chemical, microbiological, and sensory parameters and oxidative stability of LD muscle were assessed for up to 21 d of storage at 4°C under modified atmosphere packaging. Dietary AOX positively affected ( oxidative status and carcass dressing percentage. The oxidative and color stability of the LD muscle were improved ( meat from the AOX group was comparable ( meat in appearance and aroma. A lower ( < 0.05) spp. load was observed in the AOX samples than in the control samples. No other microbiological parameters were affected by dietary treatment. Overall, the present data showed that dietary AOX supplementation in pigs improved in vivo antioxidant status and exerted antioxidant and antimicrobial effects, thus enhancing the shelf life of raw pork under commercial conditions.

  7. Effects of elevated temperature and atmospheric carbon dioxide concentration on the emissions of methane and nitrous oxide from Portuguese flooded rice fields

    Science.gov (United States)

    Pereira, José; Figueiredo, Nuno; Goufo, Piebiep; Carneiro, João; Morais, Raul; Carranca, Corina; Coutinho, João; Trindade, Henrique

    2013-12-01

    Methane (CH4) and nitrous oxide (N2O) emissions from flooded rice fields have been rarely measured in Europe. A field study was carried out in an intermittent flooded rice field at central Portugal to investigate if global warming under Mediterranean conditions, elevated soil temperature (+2 °C) and atmospheric [CO2] (550 ppm), could lead to significant effects in CH4 and N2O emissions. The experimental design consisted of three treatments arranged in a randomized complete block design with three replicates. To assess the effects of ambient temperature and actual atmospheric [CO2] (375 ppm), plots were laid under open-field rice conditions. Using open-top chambers, two other treatments were established: one to assess the effect of elevated temperature and actual atmospheric [CO2] and a third treatment to evaluate the combined effect of elevated temperature and atmospheric [CO2]. Measurements of CH4 and N2O fluxes were made throughout two consecutive growing seasons in the field using the closed chamber technique. Elevation of temperature with or without elevated atmospheric [CO2] increased CH4 emissions by 50%, but this increase was not significant compared to the open-field condition. As for N2O, elevated temperature alone or combined with elevated atmospheric [CO2] had no significant effect on emissions relative to the open-field treatment. The estimated seasonal CH4 EF for the Portuguese flooded rice fields was 10.0 g CH4 m-2, while the EF for N2O emissions was 1.4% of N input. These results suggested that default seasonal CH4 and N2O EFs currently used by the Portuguese inventory were not appropriated.

  8. Capture of atmospheric CO{sub 2} into (BiO){sub 2}CO{sub 3}/graphene or graphene oxide nanocomposites with enhanced photocatalytic performance

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Wendong [Department of Scientific Research Management, Chongqing Normal University, Chongqing, 401331 (China); Dong, Fan, E-mail: dfctbu@126.com [Chongqing Key Laboratory of Catalysis and Functional Organic Molecules, College of Environment and Resources, Chongqing Technology and Business University, Chongqing, 400067 (China); Zhang, Wei, E-mail: andyzhangwei@163.com [Chongqing Institute of Green and Intelligent Technology, Chinese Academy of Sciences, Chongqing 400714 (China)

    2015-12-15

    Graphical abstract: Self-assembly of (BiO){sub 2}CO{sub 3} nanoflakes on graphene and graphene oxide nanosheets were realized by a one-pot efficient capture of atmospheric CO{sub 2} at room temperature. - Highlights: • A facile one-step method was developed for graphene-based composites. • The synthesis was conducted by utilization of atmospheric CO{sub 2}. • (BiO){sub 2}CO{sub 3}-graphene and (BiO){sub 2}CO{sub 3}-graphene oxide composites were synthesized. • The nanocomposites exhibited enhanced photocatalytic activity. - Abstract: Self-assembly of (BiO){sub 2}CO{sub 3} 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 CO{sub 2} 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){sub 2}CO{sub 3}, (BiO){sub 2}CO{sub 3}/Ge and (BiO){sub 2}CO{sub 3}/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 CO{sub 2} in green synthetic strategy.

  9. Effect of flue gas composition on deposit induced high temperature corrosion under laboratory conditions mimicking biomass firing. Part I: Exposures in oxidizing and chlorinating atmospheres

    DEFF Research Database (Denmark)

    Okoro, Sunday Chukwudi; Kiamehr, Saeed; Montgomery, Melanie

    2017-01-01

    In biomass fired power plants, deposition of alkali chlorides on superheaters, aswell as the presence of corrosive flue gas species, give rise to fast corrosion ofsuperheaters. In order to understand the corrosion mechanism under thiscomplex condition, the influence of the flue gas composition...... on hightemperature corrosion of an austenitic superheater material under laboratoryconditions mimicking biomass firing is investigated in this work. Exposuresinvolving deposit (KCl)-coated and deposit-free austenitic stainless steel (TP347H FG) samples were conducted isothermally at 560 8C for 72 h, under...... only in an oxidizing-chlorinating atmosphere, otherwise corrosionresults in formation of a duplex oxide. Corrosion attack on deposit-coatedsamples was higher than on deposit-free samples irrespective of the gaseousatmosphere. Specifically, severe volatilization of alloying elements occurred ondeposit...

  10. 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.

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

    Directory of Open Access Journals (Sweden)

    L. Xue

    2016-08-01

    Full Text Available 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.

  12. 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

  13. 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.

  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

    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. Reaction between B{sub 4}C and austenitic stainless steel in oxidizing atmosphere at temperatures below 1673 K

    Energy Technology Data Exchange (ETDEWEB)

    Sasaki, Ryosuke; Ueda, Shigeru, E-mail: tie@tagen.tohokku.ac.jp; Kim, Sun-Joong; Gao, Xu; Kitamura, Shin-ya

    2015-11-15

    Synopsis: The control rod of a light water nuclear reactor is constructed of a pole comprising stainless steel filled with a boron carbide (B{sub 4}C) core. To appraise the stability of this control rod in the event of a severe accident, the reactions of the system of B{sub 4}C and grade 304 austenitic stainless steel (SS) were observed at 1473 K in Ar, air, and a mixture of both. To clarify the reaction mechanism and the influence of the oxygen partial pressure, the weight change ratio was monitored and differential thermal analysis was performed at the temperature range from room temperature to 1673 K to monitor the reaction under controlled oxygen partial pressure. The results showed that there was no direct reaction between B{sub 4}C and SS. When the temperature was higher than the melting point of B{sub 2}O{sub 3} (743 K), the molten B{sub 2}O{sub 3} formed by oxidation of B{sub 4}C covered the surface of SS by spreading wetting. This B{sub 2}O{sub 3} layer functioned to transport oxygen from the atmosphere to SS, leading to accelerated oxidation of SS. As a result, a Fe–Cr–Ni–B–O oxide phase covered the surface of SS. Oxygen continuously entered the oxide phase with prolonged reaction time, and oxides such as Fe{sub 2}O{sub 3}, Fe{sub 3}O{sub 4}, and FeOx–Cr{sub 2}O{sub 3} were found on the outer layer. Therefore, in the presence of B{sub 2}O{sub 3} formed by oxidation of B{sub 4}C, the oxidation of SS was accelerated below the eutectic temperature of the Fe–C system. - Highlights: • The reactions of the system of B{sub 4}C and grade 304 austenitic stainless steel (SS) were studied at 1473 K. • The molten B{sub 2}O{sub 3} formed by oxidation of B{sub 4}C covered the surface of SS by spreading wetting at the temperature above 743 K. • In the presence of B{sub 2}O{sub 3}, the oxidation of SS was accelerated.

  16. Increasing the speed of computational fluid dynamics procedure for minimization the nitrogen oxide polution from the premixed atmospheric gas burner

    Directory of Open Access Journals (Sweden)

    Fotev Vasko G.

    2017-01-01

    Full Text Available This article presents innovative method for increasing the speed of procedure which includes complex computational fluid dynamic calculations for finding the distance between flame openings of atmospheric gas burner that lead to minimal NO pollution. The method is based on standard features included in commercial computational fluid dynamic software and shortens computer working time roughly seven times in this particular case.

  17. Interface properties of SiOxNy layer on Si prepared by atmospheric-pressure plasma oxidation-nitridation.

    Science.gov (United States)

    Zhuo, Zeteng; Sannomiya, Yuta; Kanetani, Yuki; Yamada, Takahiro; Ohmi, Hiromasa; Kakiuchi, Hiroaki; Yasutake, Kiyoshi

    2013-05-01

    SiOxNy films with a low nitrogen concentration (pressure plasma oxidation-nitridation process using O2 and N2 as gaseous precursors diluted in He. Interface properties of SiOxNy films have been investigated by analyzing high-frequency and quasistatic capacitance-voltage characteristics of metal-oxide-semiconductor capacitors. It is found that addition of N into the oxide increases both interface state density (Dit) and positive fixed charge density (Qf). After forming gas anneal, Dit decreases largely with decreasing N2/O2 flow ratio from 1 to 0.01 while the change of Qf is insignificant. These results suggest that low N2/O2 flow ratio is a key parameter to achieve a low Dit and relatively high Qf, which is effective for field effect passivation of n-type Si surfaces.

  18. Examining the electrical and chemical properties of reduced graphene oxide with varying annealing temperatures in argon atmosphere

    Energy Technology Data Exchange (ETDEWEB)

    Chambers, Benjamin A. [Centre for NanoScale Science and Technology, School of Chemical and Physical Sciences Flinders University, GPO Box 2100, Adelaide 5001, SA (Australia); Notarianni, Marco [Institute for Future Environments and School of Chemistry, Physics, and Mechanical Engineering, Queensland University of Technology, Brisbane 4001, QLD (Australia); Plasma-Therm LLC, 10050 16th St North, St. Petersburg, FL 33716 (United States); Liu, Jinzhang [School of Materials Science and Engineering, Beihang University, Beijing 100191 (China); Motta, Nunzio, E-mail: n.motta@qut.edu.au [Institute for Future Environments and School of Chemistry, Physics, and Mechanical Engineering, Queensland University of Technology, Brisbane 4001, QLD (Australia); Andersson, Gunther G., E-mail: Gunther.andersson@flinders.edu.au [Centre for NanoScale Science and Technology, School of Chemical and Physical Sciences Flinders University, GPO Box 2100, Adelaide 5001, SA (Australia)

    2015-11-30

    Graphical abstract: - Highlights: • Graphene oxide was reduced by annealing up to 1000 °C. • Sheet resistance of the graphene oxide layer decreases in the annealing process. • Sheet resistance decreases with increase in sp{sup 2} hybridised carbon. • Density of states at low binding energy increase with decreasing sheet resistance. - Abstract: Graphene oxide flakes were successfully fabricated and deposited as a film onto a silicon substrate. A series of these samples were annealed at various temperatures under a low pressure argon environment. The valence structure of the surface is examined using ultraviolet photoelectron spectroscopy whilst the chemical nature of the surface is examined using X-ray photoelectron spectroscopy. The sheet resistance was measured to document the performance changes with variation in electronic and chemical nature of the surface. It was found that increasing the annealing temperature increased the 2p π content leading to a better conductivity and reduction in sheet resistance.

  19. Influence of temperature and atmosphere on the strength and elastic modulus of solid oxide fuel cell anode supports

    DEFF Research Database (Denmark)

    Ni, De Wei; Charlas, Benoit; Kwok, Kawai

    2016-01-01

    Solid Oxide Fuel Cells are subjected to significant stresses during production and operation. The various stress-generating conditions impose strength requirements on the cell components, and thus the mechanical properties of the critical load bearing materials at relevant operational conditions ...

  20. 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.; De Boer, W.; 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

  1. The impact of anthropogenic emissions on atmospheric sulfate production pathways, oxidants, and ice core Δ17O(SO42–

    Directory of Open Access Journals (Sweden)

    S. A. Kunasek

    2011-04-01

    Full Text Available We use a global three-dimensional chemical transport model to quantify the influence of anthropogenic emissions on atmospheric sulfate production mechanisms and oxidant concentrations constrained by observations of the oxygen isotopic composition (Δ17O = &delta17O–0.52 × &delta18O of sulfate in Greenland and Antarctic ice cores and aerosols. The oxygen isotopic composition of non-sea salt sulfate (Δ17O(SO42– is a function of the relative importance of each oxidant (e.g. O3, OH, H2O2, and O2 during sulfate formation, and can be used to quantify sulfate production pathways. Due to its dependence on oxidant concentrations, Δ17O(SO42– has been suggested as a proxy for paleo-oxidant levels. However, the oxygen isotopic composition of sulfate from both Greenland and Antarctic ice cores shows a trend opposite to that expected from the known increase in the concentration of tropospheric O3 since the preindustrial period. The model simulates a significant increase in the fraction of sulfate formed via oxidation by O2 catalyzed by transition metals in the present-day Northern Hemisphere troposphere (from 11% to 22%, offset by decreases in the fractions of sulfate formed by O3 and H2O2. There is little change, globally, in the fraction of tropospheric sulfate produced by gas-phase oxidation (from 23% to 27%. The model-calculated change in Δ17O(SO42– since preindustrial times (1850 CE is consistent with Arctic and Antarctic observations. The model simulates a 42% increase in the concentration of global mean tropospheric O3, a 10% decrease in OH, and a 58% increase in H2O2 between the preindustrial period and present. Model results indicate that the observed decrease in the Arctic Δ17O(SO42– – in spite of increasing tropospheric O3 concentrations – can be explained by the combined effects of increased sulfate formation by O2 catalyzed by anthropogenic transition metals and increased cloud water acidity, rendering Δ17O(SO42– insensitive

  2. Atmospheric deposition of reactive nitrogen oxides and ozone in a temperate deciduous forest and a subarctic woodland: 1. Measurements and mechanisms

    Science.gov (United States)

    Munger, J. William; Wofsy, Steven C.; Bakwin, Peter S.; Fan, Song-Miao; Goulden, Michael L.; Daube, Bruce C.; Goldstein, Allen H.; Moore, Kathleen E.; Fitzjarrald, David R.

    1996-05-01

    We present 5 years of NOy and O3 eddy flux and concentration measurements and NOx concentration measurements at Harvard Forest (1990-1994), a mixed deciduous forest in central Massachusetts, and 2 months of data for a spruce woodland near Schefferville, Quebec, during the NASA ABLE3B/Northern Wetlands Study (1990). Mean midday values of net dry NOy flux from atmosphere to canopy were 3.4 and 3.2 μmole m-2 hr-1 at Harvard Forest in summer and winter, respectively, and 0.5 μmole m-2hr-1 at Schefferville during summer. Nighttime values were 1.3, 2.0, and 0.15 μmole m-2 hr-1, respectively. For 1990-1994, the net annual dry deposition of nitrogen oxides was 17.9 mmole m-2 yr-1 (2.49 kgN ha-1 y-1). Oxidized species such as HNO3 dominated N deposition, with minor contributions from direct deposition of NO2. Emissions of NO from the forest soil were negligible compared to deposition. Comparison of NOy deposition at Harvard Forest and Schefferville and analysis of the dependence on meteorological parameters show that anthropogenic sources dominate the nitrogen oxide inputs over much of North America. Heterogeneous reactions account for >90% of the conversion of NO2 to HNO3 in winter, leading to rates for dry deposition of NOy similar to fluxes in summer despite 10-fold decrease in OH concentrations. In summer, formation of HNO3 by heterogeneous reactions (mainly at night) could provide 25-45% of the NO2 oxidation.

  3. 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.

  4. 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)

  5. 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...

  6. Atmospheric-pressure cold plasma for synthesizing Pd/FeO x catalysts with enhanced low-temperature CO oxidation activity

    Science.gov (United States)

    Di, Lanbo; Li, Zhuang; Park, Dong-Wha; Lee, Byungjin; Zhang, Xiuling

    2017-06-01

    The FeO x -supported Pd catalyst prepared by co-precipitation has drawn considerable research attention owing to its low-temperature CO oxidation activity. However, Pd utilization should be improved owing to its encapsulation into the support. In this work, atmospheric-pressure cold plasma was employed to synthesize a Pd/FeO x -P catalyst for the first time. The reaction rate of the Pd/FeO x -P catalyst (at 25 °C) is 1.3 times that of the Pd/FeO x -C catalyst prepared by conventional H2 reduction and 3.5 times that in a previous work, owing to the surface enrichment of Pd species, the larger pore diameter of the FeO x support, a higher metallic Pd ratio, and abundant oxygen vacancies.

  7. Self-healing atmospheric plasma sprayed Mn1.0Co1.9Fe0.1O4 protective interconnector coatings for solid oxide fuel cells

    Science.gov (United States)

    Grünwald, Nikolas; Sebold, Doris; Sohn, Yoo Jung; Menzler, Norbert Heribert; Vaßen, Robert

    2017-09-01

    Dense coatings on metallic interconnectors are necessary to suppress chromium poisoning of SOFC cathodes. Atmospherically plasma sprayed (APS) Mn1.0Co1.9Fe0.1O4 (MCF) protective layers demonstrated reduced chromium related degradation in laboratory and stack tests. Previous analyses revealed strong microstructural changes comparing the coating's as-sprayed and operated condition. This work concentrates on the layer-densification and crack-healing observed by annealing APS-MCF in air, which simulates the cathode operation conditions. The effect is described by a volume expansion induced by a phase transformation. Reducing conditions during the spray process lead to a deposition of the MCF in a metastable rock salt configuration. Annealing in air activates diffusion processes for a phase transformation to the low temperature stable spinel phase (T gas route is blocked and further oxidation continues over solid state diffusion. The self-healing abilities of metastable APS coatings could be interesting for other applications.

  8. Removal of the potent greenhouse gas NF3 by reactions with the atmospheric oxidants O(1D), OH and O3.

    Science.gov (United States)

    Dillon, Terry J; Vereecken, Luc; Horowitz, Abraham; Khamaganov, Victor; Crowley, John N; Lelieveld, Jos

    2011-11-07

    Nitrogen trifluoride, NF(3), a trace gas of purely anthropogenic origin with a large global warming potential is accumulating in the Earth's atmosphere. Large uncertainties are however associated with its atmospheric removal rate. In this work, experimental and theoretical kinetic tools were used to study the reactions of NF(3) with three of the principal gas-phase atmospheric oxidants: O((1)D), OH and O(3). For reaction (R2) with O((1)D), rate coefficients of k(2)(212-356 K) = (2.0 ± 0.3) × 10(-11) cm(3) molecule(-1) s(-1) were obtained in direct competitive kinetics experiments, and experimental and theoretical evidence was obtained for F-atom product formation. These results indicate that whilst photolysis in the stratosphere remains the principal fate of NF(3), reaction with O((1)D) is significant and was previously underestimated in atmospheric lifetime calculations. Experimental evidence of F-atom production from 248 nm photolysis of NF(3) was also obtained, indicating that quantum yields for NF(3) destruction remain significant throughout the UV. No evidence was found for reaction (R3) of NF(3) with OH indicating that this process makes little or no contribution to NF(3) removal from the atmosphere. An upper-limit of k(3)(298 K) true rate coefficient is more than ten orders of magnitude smaller. An upper-limit of k(4)(296 K) < 3 × 10(-25) cm(3) molecule(-1) s(-1) was obtained in experiments to investigate O(3) + NF(3) (R4). Altogether these results underpin calculations of a long (several hundred year) lifetime for NF(3). In the course of this work rate coefficients (in units of 10(-11) cm(3) molecule(-1) s(-1)) for removal of O((1)D) by n-C(5)H(12), k(6) = (50 ± 5) and by N(2), k(7) = (3.1 ± 0.2) were obtained. Uncertainties quoted throughout are 2σ precision only. This journal is © the Owner Societies 2011

  9. On the use of UV photo-oxidation for the determination of total nitrogen in rainwater and water-extracted atmospheric aerosol

    Science.gov (United States)

    Mace, Kimberly A.; Duce, Robert A.

    Three methods are currently in use for the determination of total N within rainwater and water-extracted aerosols—UV photo-oxidation, persulfate digestion, and high-temperature combustion. Among these methods, UV photo-oxidation has received scrutiny for its reported inability to digest "refractory" organic N compounds. In this manuscript we utilized inorganic and organic nitrogen standards to carefully assess the ability of a specific UV digestor, the Metrohm 705 UV digestor, to correctly digest organic N within dilute solutions (such as rainwater and atmospheric aerosol). We also discuss the negative aspects of the three methods listed above, comment on the photochemical reactions and chemical products produced by exposure to UV light, and make suggestions concerning the proper use of UV digestion technique when determining total N. Our tests indicate that at a digestion time of 2 h and a temperature of 85°C the system is satisfactory for determining the total amount of organic N within dilute solutions. The upper concentration limit using this UV system was found to be 50 μM N of organic N. Diluted samples were found to carry a larger burden of analytical error due to the combined effects of UV blanks (that can range from 0.1-0.6 μM N) and the uncertainty associated with the chromatographic ion analysis (for nitrate, nitrite, and ammonium). This error can often lead to negative values when reporting organic N. We suggest that negative values for organic N be included within the mean and standard deviation of organic N measurements rather than excluding them by rounding negative values to zero. Only by including all analytical error within measurements will true concentrations of organic N within rainwater and atmospheric aerosols and its relevance to total N budgets be known.

  10. UV Absorption Cross Sections of Nitrous Oxide (N2O) and Carbon Tetrachloride (CCl4) Between 210 and 350 K and the Atmospheric Implications

    Science.gov (United States)

    Carlon, Nabilah Rontu; Papanastasiou, Dimitrios K.; Fleming, Eric L.; Jackman, Charles H.; Newman, Paul A.; Burkholder, James B.

    2010-01-01

    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 27 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 37 atmospheric model calculations is presented.

  11. Global change impact on oxidative potential and toxicity of atmospheric particles from the East Mediterranean basin: the ARCHIMEDES initiative

    Science.gov (United States)

    Alleman, Laurent; Anthérieu, Sébastien; Baeza-Squiban, Armelle; Garçon, Guillaume; Lo Guidice, Jean-Marc; Hamonou, Eric; Öztürk, Fatma; Perdrix, Esperanza; Rudich, Yinon; Sciare, Jean; Sauvage, Stéphane

    2017-04-01

    Climate change (CC) has important social, economical and health implications, notably in accordance with variation in air pollution or microbiome modification and its related toxicity mechanisms. CC will have a strong influence on meteorology, inducing dryer and warmer conditions in some regions. The Mediterranean basin is foreseen as a hotspot for regional climate warming, favoring larger dust episodes, wild fire events, vegetation emissions and changes in air pollution physic-chemical characteristics due to enhanced photochemical reactivity. Increasing concentrations of biogenic volatile organic compounds (VOCs), ozone, and radicals will be associated with rising concentrations of secondary organic aerosols (SOA) and other oxidized aerosols. These expected changes in aerosol composition are currently studied within the international ChArMEx (Chemistry-aerosol Mediterranean Experiment) program, part of the interdisciplinary MISTRALS metaprogramme (Mediterranean Integrated STudies at Regional And Local Scales). According to the LIFE/MED-PARTICLES (LIFE) project, this might result in more adverse effects on health. However, toxicologists are far from having a detailed mechanistic knowledge of the quantitative causal relations between particles (PM) and health effects suggested by epidemiological evidences. Detailed toxicological studies looking at contrasted PM origins and chemical compositions are highly needed, particularly on strongly aged SOA suspected to increase the oxidative potential (OP) and to enhance the toxicity of airborne particles. Intensive researches onto the underlying mechanisms of inflammation started to describe the outlines of the intricate relationship between oxidative stress and inflammation. It is therefore, of great importance to better determine the OP of PM from contrasted surroundings, its relationship with CC through PM's physical, chemical and microbial characteristics, and its toxicological consequences within the lungs. Recently

  12. A case study of the relative effects of power plant nitrogen oxides and sulfur dioxide emission reductions on atmospheric nitrogen deposition.

    Science.gov (United States)

    Vijayaraghavan, Krish; Seigneur, Christian; Bronson, Rochelle; Chen, Shu-Yun; Karamchandani, Prakash; Walters, Justin T; Jansen, John J; Brandmeyer, Jo Ellen; Knipping, Eladio M

    2010-03-01

    The contrasting effects of point source nitrogen oxides (NOx) and sulfur dioxide (SO2) air emission reductions on regional atmospheric nitrogen deposition are analyzed for the case study of a coal-fired power plant in the southeastern United States. The effect of potential emission reductions at the plant on nitrogen deposition to Escambia Bay and its watershed on the Florida-Alabama border is simulated using the three-dimensional Eulerian Community Multiscale Air Quality (CMAQ) model. A method to quantify the relative and individual effects of NOx versus SO2 controls on nitrogen deposition using air quality modeling results obtained from the simultaneous application of NOx and SO2 emission controls is presented and discussed using the results from CMAQ simulations conducted with NOx-only and SO2-only emission reductions; the method applies only to cases in which ambient inorganic nitrate is present mostly in the gas phase; that is, in the form of gaseous nitric acid (HNO3). In such instances, the individual effects of NOx and SO2 controls on nitrogen deposition can be approximated by the effects of combined NOx + SO2 controls on the deposition of NOy, (the sum of oxidized nitrogen species) and reduced nitrogen species (NHx), respectively. The benefit of controls at the plant in terms of the decrease in nitrogen deposition to Escambia Bay and watershed is less than 6% of the overall benefit due to regional Clean Air Interstate Rule (CAIR) controls.

  13. Atmospheric application of trace amounts of nitric oxide enhances tolerance to salt stress and improves nutritional quality in spinach (Spinacia oleracea L.).

    Science.gov (United States)

    Du, Shao-Ting; Liu, Yue; Zhang, Peng; Liu, Hui-Jun; Zhang, Xue-Qing; Zhang, Ran-Ran

    2015-04-15

    The increased salinity in greenhouses has become a problem of great concern. In this study, it was observed that the salt-induced oxidative damages (indicated by MDA, H2O2 and antioxidant enzymes, including POD, SOD and CAT) could be alleviated by application of NO gas. Consequently, although both photosynthesis and growth in plants were inhibited by NaCl stress, they were restored by NO gas application, and the fresh and dry biomasses of edible parts increased by 60% and 27% over NaCl stress treatment, respectively. Furthermore, gaseous NO application also significantly elevated the levels of several antioxidation-associated compounds such as proline, ascorbate, glutathione, total phenolics and flavonoids, as well as the total antioxidant capacity (indicated by DPPH scavenging activity) in NaCl-treated plants. Keeping in mind all of the above, we concluded that atmospheric application of trace amounts of nitric oxide gas could be an effective strategy for improving both biomass production and nutrition quality in spinach under salt stress. Copyright © 2014 Elsevier Ltd. All rights reserved.

  14. Degradation of cationic red GTL by catalytic wet air oxidation over Mo-Zn-Al-O catalyst under room temperature and atmospheric pressure.

    Science.gov (United States)

    Xu, Yin; Li, Xiaoyi; Cheng, Xiang; Sun, Dezhi; Wang, Xueye

    2012-03-06

    To overcome the drawback of catalytic wet air oxidation (CWAO) with high temperature and high pressure, the catalytic activity of Mo-Zn-Al-O catalyst for degradation of cationic red GTL under room temperature and atmospheric pressure was investigated. Mo-Zn-Al-O catalyst was prepared by coprecipitation and impregnation. XRD, TG-DTG, and XPS were used to characterize the resulting sample. Central composition design using response surface methodology was employed to optimize correlation of factors on the decolorization of cationic red GTL. The results show that the optimal conditions of pH value, initial concentration of dye and catalyst dosage were found to be 4.0, 85 mg/L and 2.72 g/L, respectively, for maximum decolorization of 80.1% and TOC removal of 50.9%. Furthermore, the reaction on the Mo-Zn-Al-O catalyst and degradation mechanism of cationic red GTL was studied by Electron spin resonance (ESR) and GC-MS technique. The possible reaction mechanism was that the Mo-Zn-Al-O catalyst can efficiently react with adsorbed oxygen/H(2)O to produce ·OH and (1)O(2) and finally induce the degradation of cationic red GTL. GC-MS analysis of the degradation products indicates that cationic red GTL was initiated by the cleavage of -N ═ N- and the intermediates were further oxidized by ·OH or (1)O(2).

  15. 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 < 9.0 × 10(-22) cm(3) molecule(-1) s(-1). In 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.

  16. Influence of temperature and atmosphere on the strength and elastic modulus of solid oxide fuel cell anode supports

    DEFF Research Database (Denmark)

    Ni, De Wei; Charlas, Benoit; Kwok, Kawai

    2016-01-01

    Solid Oxide Fuel Cells are subjected to significant stresses during production and operation. The various stress-generating conditions impose strength requirements on the cell components, and thus the mechanical properties of the critical load bearing materials at relevant operational conditions...... need to be characterized to ensure reliable operation. In this study, the effect of reduction temperature on microstructural stability, high temperature strength and elastic modulus of Ni-YSZ anode supports were investigated. The statistical distribution of strength was determined from a large number...... of samples (∼30) at each condition to ensure high statistical validity. It is revealed that the microstructure and mechanical properties of the Ni-YSZ strongly depend on the reduction temperature. Further studies were conducted to investigate the temperature dependence of the strength and elastic modulus...

  17. 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.

  18. The nitrogen cycle: Atmosphere interactions

    Science.gov (United States)

    Levine, J. S.

    1984-01-01

    Atmospheric interactions involving the nitrogen species are varied and complex. These interactions include photochemical reactions, initiated by the absorption of solar photons and chemical kinetic reactions, which involve both homogeneous (gas-to-gas reactions) and heterogeneous (gas-to-particle) reactions. Another important atmospheric interaction is the production of nitrogen oxides by atmospheric lightning. The nitrogen cycle strongly couples the biosphere and atmosphere. Many nitrogen species are produced by biogenic processes. Once in the atmosphere nitrogen oxides are photochemically and chemically transformed to nitrates, which are returned to the biosphere via precipitation, dry deposition and aerosols to close the biosphere-atmosphere nitrogen cycle. The sources, sinks and photochemistry/chemistry of the nitrogen species; atmospheric nitrogen species; souces and sinks of nitrous oxide; sources; sinks and photochemistry/chemistry of ammonia; seasonal variation of the vertical distribution of ammonia in the troposphere; surface and atmospheric sources of the nitrogen species, and seasonal variation of ground level ammonia are summarized.

  19. Atmospheric pressure plasma oxidation of AA6061-T6 aluminum alloy surface for strong and durable adhesive bonding applications

    Science.gov (United States)

    Saleema, N.; Gallant, D.

    2013-10-01

    AA 6061-T6 aluminum alloy surface has been treated using atmospheric pressure helium-oxygen plasma at room temperature prior to bonding with a bi-component epoxy resin. The adhesive joint strengths were evaluated via single lap shear tests as prepared (pristine conditions) as well as following degradation by exposure to extreme temperature and humidity conditions (cataplasma conditions). Very high adhesion strength of 24 ± 1 MPa was achieved on surfaces after a very short exposure of the He/O2 plasma of only 15 s under pristine conditions resulting in cohesive failure of the adhesive itself. Best results were obtained under cataplasma conditions with adhesion strength of 22.6 ± 1 MPa by introducing a very simple pretreatment with scotch brite® prior to plasma exposure. With many different surface treatment methods being predominantly tested and evaluated, the adhesive bonding community may highly benefit from the present work as the treatment method uses very simple, economical and safe procedures in obtaining results comparable to benchmark methods such as Forest Products Laboratory (FPL) etch, anodization and so on.

  20. 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...

  1. 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

  2. An ab initio Molecular Dynamics study of the solvated OHCl- complex. Implications for the atmospheric oxidation of (Cl-)aq to (Cl2)g

    Energy Technology Data Exchange (ETDEWEB)

    D' Auria, R; Kuo, I W; Tobias, D J

    2007-07-26

    We have studied the OHCl{sup -} complex in a six water cluster and in bulk liquid water by means of generalized gradient-corrected BLYP density functional theory based Born-Oppenheimer molecular dynamics. Self-interaction corrected results, that predict an H-bonded OH...Cl{sup -} complex, are compared to the uncorrected ones, that predict a bonded (HO-Cl){sup -}. A second order Moeller-Plesset potential energy landscape of the gas-phase complex in its ground state was computed to determine which of the two configurations represents the true nature of the bond. Since no evidence of a local minimum was found in the vicinity of the geometry corresponding to the (HO-Cl){sup -} we conclude that the complex is held together by a H-bond like interaction in both an asymmetric solvation environment, as represented by the cluster, and in a symmetric solvation environment, as represented by the bulk system. In the limits of the present results we postulate that the mechanism that governs the atmospheric oxidation of (Cl{sup -}){sub int} to (Cl{sub 2}){sub gas} on the surface of marine aerosols [Knipping et al. 2000] is initiated by the formation of an H-bonded OH...Cl{sup -} complex. Furthermore, since no evidence of charge transfer mechanism from Cl{sup -} to OH was found, in the liquid as well as in the cluster environments, a likely second step toward the oxidation of Cl{sup -} should consist in the reaction of the complex with a second Cl{sup -} that would result in the formation of the species Cl{sup -2} and OH{sup -}. (Cl{sub 2}){sub g} could then be formed upon charge exchange reaction with an impinging OH molecule.

  3. 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.

  4. The influence of diesel-truck exhaust particles on the kinetics of the atmospheric oxidation of dissolved sulfur dioxide by oxygen.

    Science.gov (United States)

    Meena, Vimlesh Kumar; Dhayal, Yogpal; Saxena, Deepa; Rani, Ashu; Chandel, C P Singh; Gupta, K S

    2016-09-01

    The automobile exhausts are one of the major sources of particulate matter in urban areas and these particles are known to influence the atmospheric chemistry in a variety of ways. Because of this, the oxidation of dissolved sulfur dioxide by oxygen was studied in aqueous suspensions of particulates, obtained by scraping the particles deposited inside a diesel truck exhaust pipe (DEP). A variation in pH showed the rate to increase with increase in pH from 5.22 to about ∼6.3 and to decrease thereafter becoming very slow at pH = 8.2. In acetate-buffered medium, the reaction rate was higher than the rate in unbuffered medium at the same pH. Further, the rate was found to be higher in suspension than in the leachate under otherwise identical conditions. And, the reaction rate in the blank reaction was the slowest. This appears to be due to catalysis by leached metal ions in leachate and due to catalysis by leached metal ions and particulate surface both in suspensions. The kinetics of dissolved SO2 oxidation in acetate-buffered medium as well as in unbuffered medium at pH = 5.22 were defined by rate law: k obs  = k 0 + k cat [DEP], where k obs and k 0 are observed rate constants in the presence and the absence of DEP and k cat is the rate constant for DEP-catalyzed pathway. At pH = 8.2, the reaction rate was strongly inhibited by DEP in buffered and unbuffered media. Results suggest that the DEP would have an inhibiting effect in those areas where rainwater pH is 7 or more. These results at high pH are of particular significance to the Indian subcontinent, because of high rainwater pH. Conversely, it indicates the DEP to retard the oxidation of dissolved SO2 and control rainwater acidification.

  5. 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)

  6. 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.

  7. 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.

  8. Atmospheric pollution; Pollution atmospherique

    Energy Technology Data Exchange (ETDEWEB)

    Lambrozo, J.; Guillossou, G. [EDF-Gas de France, Service des Etudes Medicales, 75 - Paris (France)

    2008-10-15

    The atmosphere is the reservoir of numerous pollutants (nitrogen oxides, sulfur oxides, carbon oxides, particulates, volatile organic compounds, polycyclic aromatic hydrocarbons) from natural origin or anthropogenic origin ( industry, transport, agriculture, district heating). With epidemiologic studies the atmospheric pollution is associated with an increase of respiratory and cardiovascular diseases. At the european level, the technological progress, the legislation have allowed a reduction of pollutant emissions, however these efforts have to be continued because the sanitary impact of atmospheric pollution must not be underestimated, even if the risks appear less important that these ones in relation with tobacco, inside pollution or others factors of cardiovascular risks. Indeed, on these last factors an individual action is possible for the exposure to air pollution people have no control. (N.C.)

  9. 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.

  10. 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.

  11. 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...

  12. 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.

  13. 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

    ) which indicate a predominance of anoxic water columns (FeHR/Fetot > 0.38) during the onset of oxidation pulses. We favor the scenario by which isotopically heavy Cr(VI) entered the basin after pulses of oxidative weathering on land and in which Fe(II) accumulated in the water column. Neodymium isotopes...

  14. Atmospheric Dispositifs

    DEFF Research Database (Denmark)

    Wieczorek, Izabela

    2015-01-01

    Through the coupling of dispositif with atmosphere this paper engages in a discussion of the atmospherics as both a form of knowledge and a material practice. In doing so the objective is to provide an inventory of tools and methodologies deployed in the construction of atmosphere understood......, the conceptual foundations and protocols for the production of atmosphere in architecture might be found beneath the surface of contemporary debates. In this context, the notion of atmospheric dispositif – illustrated through an oeuvre of the German architect Werner Ruhnau and its theoretical and historical...

  15. In situ Raman and in situ XRD analysis of PdO reduction and Pd° oxidation supported on γ-Al2O3 catalyst under different atmospheres.

    Science.gov (United States)

    Baylet, Alexandre; Marécot, Patrice; Duprez, Daniel; Castellazzi, Paola; Groppi, Gianpiero; Forzatti, Pio

    2011-03-14

    Reduction of Pd° and decomposition of palladium oxide supported on γ-alumina were studied at atmospheric pressure under different atmospheres (H(2), CH(4), He) over a 4 wt% Pd/Al(2)O(3) catalyst (mean palladium particle size: 5 nm with 50% of small particles of size below 5 nm). During temperature programmed tests (reduction, decomposition and oxidation) the crystal domain behaviour of the PdO/Pd° phase was evaluated by in situ Raman spectroscopy and in situ XRD analysis. Under H(2)/N(2), the reduction of small PdO particles (5 nm) starts at 100 °C and is achieved at 150 °C. Subsequent oxidation in O(2)/N(2) leads to reoxidation of small crystal domain at ambient temperature while oxidation of large particles starts at 300 °C. Under CH(4)/N(2), the small particle reduction occurs between 240 and 250 °C while large particle reduction is fast and occurs between 280 and 290 °C. Subsequent reoxidation of the catalyst reduced in CH(4)/N(2) shows that small and large particle oxidation of Pd° starts also at 300 °C. Under He, no small particle decomposition is observed probably due to strong interactions between particles and support whereas large particle reduction occurs between 700 and 750 °C. After thermal decomposition under He, the oxidation starts at 300 °C. Thus, the reduction phenomenon (small and large crystal domain) depends on the nature of the reducing agent (H(2), CH(4), He). However, whatever the reduction or decomposition treatment or the crystal domain, Pd° oxidation starts at 300 °C and is completed only at temperatures higher than 550 °C. Under lean conditions, with or without water, the palladium consists of reduced sites of palladium (Pd°, Pd(δ+) with δ PdO(x) with x < 1) randomly distributed on palladium particles.

  16. 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

  17. 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 exper......” implications and qualities of the approach are identified through concrete examples of a design case, which also investigates the qualities and implications of addressing atmospheres both as design concern and user experience.......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...

  18. 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......, bioaccumulative, and potentially toxic Molar yields of PFOA depend on location and season, are in the range of 1-10 and are of the correct order of magnitude to explain the observed levels in Arctic fauna. Fluorotelomer alcohols such as n-C8F17CH2CH2OH appear to be a significant global source of persistent...

  19. 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

  20. Atmospheric Neutrinos

    Directory of Open Access Journals (Sweden)

    Takaaki Kajita

    2012-01-01

    Full Text Available 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 atmospheric neutrino experiments and the neutrino oscillation studies with these neutrinos.

  1. Surface enrichment of Pt in stable Pt-Ir nano-alloy particles on MgAl 2 O 4 spinel in oxidizing atmosphere

    Energy Technology Data Exchange (ETDEWEB)

    Li, Weizhen; Nie, Lei; Chen, Ying; Kovarik, Libor; Liu, Jun; Wang, Yong

    2017-04-01

    With the capability of MgAl2O4 spinel {111} nano-facets in stabilizing small Rh, Ir and Pt particles, bimetallic Ir-Pt catalysts on the same support were investigated, aiming at further lowering the catalyst cost by substituting expensive Pt with cheaper Ir in the bulk. Small Pt-Ir nano-alloy particles (< 2nm) were successfully stabilized on the spinel {111} nano-facets as expected. Interestingly, methanol oxidative dehydrogenation (ODH) rate on the surface Pt atoms increases with oxidizing aging but decreases upon reducing treatment, where Ir is almost inactive under the same reaction conditions. Up to three times enhancement in Pt exposure was achieved when the sample was oxidized at 800 °C in air for 1 week and subsequently reduced by H2 for 2 h, demonstrating successful surface enrichment of Pt on Pt-Ir nano-alloy particles. A dynamic stabilization mechanism involving wetting\

  2. Urban atmospheres.

    Science.gov (United States)

    Gandy, Matthew

    2017-07-01

    What is an urban atmosphere? How can we differentiate an 'atmosphere' from other facets of urban consciousness and experience? This essay explores some of the wider cultural, political, and philosophical connotations of atmospheres as a focal point for critical reflections on space and subjectivity. The idea of an 'affective atmosphere' as a distinctive kind of mood or shared corporeal phenomenon is considered in relation to recent developments in phenomenology, extended conceptions of agency, and new understandings of materialism. The essay draws in particular on the changing characteristics of air and light to reflect on different forms of sensory experience and their wider cultural and political connotations. The argument highlights some of the tensions and anomalies that permeate contemporary understandings of urban atmospheres.

  3. The determination and fate of disinfection by-products from ozonation-chlorination of fulvic acid.

    Science.gov (United States)

    Zhong, Xin; Cui, Chongwei; Yu, Shuili

    2017-03-01

    Ozonation of fulvic acid (FA) can result in diverse intermediate oxidation by-products, significantly affecting disinfection by-product (DBP) formation following chlorination. The objective of this study was to provide insight into ozone reaction intermediates and reveal the possible formation pathway of DBPs from ozonation of FA due to the formation of intermediate oxidation by-products. Aldehydes, aromatic acids, short-chain acids, chloroform, and dichloroacetic acid were detected at various ozone dosage additions. Aromatic acids were studied by using solid-phase extraction-ultra high-performance liquid chromatography (SPE-UPLC). This new analytical approach enables the extraction and analysis of highly polar carboxylic acids that are difficult to measure using conventional methods. The results showed that formaldehyde, acetaldehyde, glyoxal, methyl-glyoxal, fumaric, malonic protocatechuic, 3-hydroxybenzoic, and benzoic acid were predominant oxidation by-products. The yields of the four aldehydes increased steadily with ozone dosage. When ozone dosage was 2∼2.5 mg/l, the amount of carboxylic acids was largest, and the total amount of the carboxylic acids was about 5∼10 times higher than that of the aldehydes. Besides, hydroxybenzoic acids are the major precursor, although they have low content in ozone reaction solution, they have a great contribution to the DBP formation. This study provides a new perspective on ozonation natural organic matter, which contributes to understand the other sources of DBPs and thus broadens the knowledge of drinking water treatment.

  4. 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.

  5. 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)

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

    2011-01-01

    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...

  6. 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. Copyright © 2015 Elsevier Ltd. All rights reserved.

  7. Speciation and distribution of vanadium in drinking water iron pipe corrosion by-products.

    Science.gov (United States)

    Gerke, Tammie L; Scheckel, Kirk G; Maynard, J Barry

    2010-11-01

    Vanadium (V) when ingested from drinking water in high concentrations (>15 μg L(-1)) is a potential health risk and is on track to becoming a regulated contaminant. High concentrations of V have been documented in lead corrosion by-products as Pb(5)(V(5+)O(4))(3)Cl (vanadinite) which, in natural deposits is associated with iron oxides/oxyhydroxides, phases common in iron pipe corrosion by-products. The extent of potential reservoirs of V in iron corrosion by-products, its speciation, and mechanism of inclusion however are unknown. The aim of this study is to assess these parameters in iron corrosion by-products, implementing synchrotron-based μ-XRF mapping and μ-XANES along with traditional physiochemical characterization. The morphologies, mineralogies, and chemistry of the samples studied are superficially similar to typical iron corrosion by-products. However, we found V present as discrete grains of Pb(5)(V(5+)O(4))(3)Cl likely embedded in the surface regions of the iron corrosion by-products. Concentrations of V observed in bulk XRF analysis ranged from 35 to 899 mg kg(-1). We calculate that even in pipes with iron corrosion by-products with low V concentration, 100 mg kg(-1), as little as 0.0027% of a 0.1-cm thick X 100-cm long section of that corrosion by-product needs to be disturbed to increase V concentrations in the drinking water at the tap to levels well above the 15 μg L(-1) notification level set by the State of California and could adversely impact human health. In addition, it is likely that large reservoirs of V are associated with iron corrosion by-products in unlined cast iron mains and service branches in numerous drinking water distribution systems. Copyright © 2010 Elsevier B.V. All rights reserved.

  8. Atmospheric Infancy

    DEFF Research Database (Denmark)

    Roald, Tone; Pedersen, Ida Egmose; Levin, Kasper

    2017-01-01

    In this article we establish intersubjective meaning-making in infancy as atmospheric. Through qualitative descriptions of five mother–infant dyads in a video-recorded, experimental setting when the infant is 4, 7, 10, and 13 months, we discovered atmospheric appearances with a developmental...... pattern of atmospheric variations. These appearances, we argue, are contextual and intersubjective monologues. The monologues are similar to what Daniel Stern describes with his concept of “vitality affects,” but they arise as a unified force that envelops the mother and child. As such, we present a new...

  9. Air Quality Criteria for Sulfur Oxides.

    Science.gov (United States)

    National Air Pollution Control Administration (DHEW), Washington, DC.

    Included is a literature review which comprehensively discusses knowledge of the sulfur oxides commonly found in the atmosphere. The subject content is represented by the 10 chapter titles: Physical and Chemical Properties and the Atmospheric Reactions of the Oxides of Sulfur; Sources and Methods of Measurements of Sulfur Oxides in the Atmosphere;…

  10. 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.

  11. The synthesis of tungsten trioxide gel by dissolution of tungsten in hydrogen peroxide and its transformations during the heat treatment in oxidation and reduction atmospheres

    Directory of Open Access Journals (Sweden)

    Georgijević Radovan

    2011-01-01

    Full Text Available The structure and the thermal behavior of WO3 samples in air and in reduction atmosphere were studied. The sample I was prepared by the dissolution of fine metallic tungsten powder in hydrogen peroxide followed by solvent evaporation in the air at 60°C. Sample II was obtained by draining a part of the sample I at 60°C and then heating it up to 430°C. By the means of X-ray diffractometry, scanning electron microscopy and thermal analysis it was evidenced that the sample I was the amorphous hydrated gel, with the WO3•1.5H2O composition, while the second one was the anhidrous monoclinic WO3 with the mean particle size of 100 nm. Additionally, using the thermogravimetric and the differential thermal analysis simultaneously in the reduction atmosphere, both samples types were examined. After reduction the distribution of the metal particles number in respect to the diameters of the anhidrous sample was examined using the electron microscopy.

  12. Identification of market bags composition for biodegradable and oxo-biodegradable samples through thermal analysis in inert and oxidizer atmosphere; Identificacao da composicao de amostras de sacolas plasticas biodegradaveis e oxobiodegradaveis atraves de analises termicas em atmosfera inerte e oxidante

    Energy Technology Data Exchange (ETDEWEB)

    Finzi-Quintao, Cristiane M., E-mail: inzi@ufsj.edu.br [Universidade Federal de Sao Joao del-Rei (UFSJ), MG (Brazil); Novack, Katia M. [Universidade Federal de Ouro Preto (DEQUI/UFOP), MG (Brazil)

    2015-07-01

    Plastic films used to make market bags are based on polymers such as polyethylene, polystyrene and polypropylene, these materials require a long time to degrade in the environment. The alternative technologies of polymers have been developed to reduce the degradation time and the impact on the environment caused by the conventional materials, using pro-degrading additives or by the development biodegradable polymers. In Brazil, the laws of some municipalities require the use of biodegradable material in the production of market bags but the absence of specific surveillance policies makes its chemical composition unknown. In this paper, we analyzed 7 samples that was obtained from a a trading company and commercial market of Belo Horizonte . The samples were characterized by TGA / DTA , XRF , FTIR and MEV which allowed the identification and evaluation of the thermal behavior of the material in inert and oxidizing atmosphere. (author)

  13. Atmospheric chemistry of CH3O(CF2CF2O)(n)CH3 (n=1-3): Kinetics and mechanism of oxidation initiated by Cl atoms and OH radicals, IR spectra, and global warmin potentials

    DEFF Research Database (Denmark)

    Andersen, Mads Peter Sulbæk; Hurley, MD; Wallington, TJ

    2004-01-01

    Smog chambers equipped with FTIR spectrometers were used to study the Cl atom and OH radical initiated oxidation of CH3O(CF2CF2O)(n)CH3 (n = 1-3) in 720 +/- 20 Torr of air at 296 +/- 3 K. Relative rate techniques were used to measure k(Cl + CH3O(CF2CF2O)(n)CH3) (3.7 +/- 10.7) x 10(-13) and k(OH +...... of 0.051, 0.058, and 0.055 (100 year time horizon, relative to CFC-11) for CH3OCF2CF2OCH3, CH3O(CF2CF2O)(2)CH3, and CH3O(CF2CF2O)(3)CH3, respectively. Results are discussed with respect to the atmospheric chemistry of hydrofluoropolyethers (HFPEs)....

  14. Atmospheric neutrinos

    Energy Technology Data Exchange (ETDEWEB)

    Kajita, Takaaki [Research Center for Cosmic Neutrinos, Institute for Cosmic Ray Research, University of Tokyo, Kashiwa-no-ha 5-1-5, Kashiwa, Chiba 277-8582 (Japan)

    2004-12-01

    Neutrino oscillation was discovered through the study of atmospheric neutrinos. 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 and electrons. Depending on the energy of the neutrinos, atmospheric neutrinos are observed as fully contained events, partially contained events and upward-going muon events. The energy range covered by these events is from a few hundred MeV to >1 TeV. Data from various experiments showed zenith angle- and energy-dependent deficit of {nu}{sub {mu}} events, while {nu}{sub e} events did not show any such effect. It was also shown that the {nu}{sub {mu}} survival probability obeys the sinusoidal function as predicted by neutrino oscillations. Two-flavour {nu}{sub {mu}} {r_reversible} {nu}{sub {tau}} oscillations, with sin{sup 2} 2{theta} > 0.90 and {delta}m{sup 2} in the region of 1.9 x 10{sup -3} to 3.0 x 10{sup -3} eV{sup 2}, explain all these data. Various detailed studies using high statistics atmospheric neutrino data excluded the alternative hypotheses that were proposed to explain the {nu}{sub {mu}} deficit.

  15. 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

    Long path length FTIR-smog chamber techniques were used to measure k(OH + cis-CF3CH@CHF) = (1.20 ± 0.14) 1012 and k(O3 + cis-CF3CH@CHF) = (1.65 ± 0.16) 1021 cm3 molecule 1 s1 in 700 Torr of N2/O2 diluent at 296 K. The OH initiated oxidation of cis-CF3CH@CHF gives CF3CHO and HCOF in molar yields w...

  16. 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.

  17. 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...

  18. The formation and control of emerging disinfection by-products of health concern.

    Science.gov (United States)

    Krasner, Stuart W

    2009-10-13

    When drinking water treatment plants disinfect water, a wide range of disinfection by-products (DBPs) of health and regulatory concern are formed. Recent studies have identified emerging DBPs (e.g. iodinated trihalomethanes (THMs) and acids, haloacetonitriles, halonitromethanes (HNMs), haloacetaldehydes, nitrosamines) that may be more toxic than some of the regulated ones (e.g. chlorine- and bromine-containing THMs and haloacetic acids). Some of these emerging DBPs are associated with impaired drinking water supplies (e.g. impacted by treated wastewater, algae, iodide). In some cases, alternative primary or secondary disinfectants to chlorine (e.g. chloramines, chlorine dioxide, ozone, ultraviolet) that minimize the formation of some of the regulated DBPs may increase the formation of some of the emerging by-products. However, optimization of the various treatment processes and disinfection scenarios can allow plants to control to varying degrees the formation of regulated and emerging DBPs. For example, pre-disinfection with chlorine, chlorine dioxide or ozone can destroy precursors for N-nitrosodimethylamine, which is a chloramine by-product, whereas pre-oxidation with chlorine or ozone can oxidize iodide to iodate and minimize iodinated DBP formation during post-chloramination. Although pre-ozonation may increase the formation of trihaloacetaldehydes or selected HNMs during post-chlorination or chloramination, biofiltration may reduce the formation potential of these by-products.

  19. 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

    respectively. Using relative rate techniques, a value of k(Cl + CF3(CF2)(3)CH2CHO) = (1.84 +/- 0.30) x 10(-11) cm(3) molecule(-1) s(-1) was determined. The yield of the perfluorinated acid, CF3(CF2)(3)COOH, from the 4:2 fluorotelomer alcohol increased with the diluent gas oxygen concentration....... For the experimental conditions used herein and employing > 98% consumption of 4:2 fluorotelomer alcohol, the molar yields of CF3(CF2)(3)COOH were ...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...

  20. Spatial Atmospheric Pressure Atomic Layer Deposition of Tin Oxide as an Impermeable Electron Extraction Layer for Perovskite Solar Cells with Enhanced Thermal Stability.

    Science.gov (United States)

    Hoffmann, Lukas; Brinkmann, Kai O; Malerczyk, Jessica; Rogalla, Detlef; Becker, Tim; Theirich, Detlef; Shutsko, Ivan; Görrn, Patrick; Riedl, Thomas

    2018-02-14

    Despite the notable success of hybrid halide perovskite-based solar cells, their long-term stability is still a key-issue. Aside from optimizing the photoactive perovskite, the cell design states a powerful lever to improve stability under various stress conditions. Dedicated electrically conductive diffusion barriers inside the cell stack, that counteract the ingress of moisture and prevent the migration of corrosive halogen species, can substantially improve ambient and thermal stability. Although atomic layer deposition (ALD) is excellently suited to prepare such functional layers, ALD suffers from the requirement of vacuum and only allows for a very limited throughput. Here, we demonstrate for the first time spatial ALD-grown SnO x at atmospheric pressure as impermeable electron extraction layers for perovskite solar cells. We achieve optical transmittance and electrical conductivity similar to those in SnO x grown by conventional vacuum-based ALD. A low deposition temperature of 80 °C and a high substrate speed of 2.4 m min -1 yield SnO x layers with a low water vapor transmission rate of ∼10 -4 gm -2 day -1 (at 60 °C/60% RH). Thereby, in perovskite solar cells, dense hybrid Al:ZnO/SnO x electron extraction layers are created that are the key for stable cell characteristics beyond 1000 h in ambient air and over 3000 h at 60 °C. Most notably, our work of introducing spatial ALD at atmospheric pressure paves the way to the future roll-to-roll manufacturing of stable perovskite solar cells.

  1. Digestion kinetics of carbohydrate fractions of citrus by-products.

    Science.gov (United States)

    Lashkari, Saman; Taghizadeh, Akbar

    2015-01-01

    The present experiment was carried out to determine the digestion kinetics of carbohydrate fractions of citrus by-products. Grapefruit pulp (GP), lemon pulp (LE), lime pulp (LI) and orange pulp (OP) were the test feed. Digestion kinetic of whole citrus by-products and neutral detergent fiber (NDF) fraction and acid detergent fiber (ADF) fractions of citrus by-products were measured using the in vitro gas production technique. Fermentation kinetics of the neutral detergent soluble carbohydrates (NDSC) fraction and hemicelluloses were calculated using a curve subtraction. The fermentation rate of whole was the highest for the LE (p citrus by-products lag time was longer for hemicellulose than other carbohydrate fractions. There was no significant difference among potential gas production (A) volumes of whole test feeds (p citrus by-products have high potential for degradability. It could also be concluded that carbohydrate fractions of citrus by-products have remarkable difference in digestion kinetics and digestive behavior.

  2. Halogenated by-products of disinfecting ozonised recreational waters; Subproductos halaogenados de desinfeccion en aguas recreacionales ozonizadas

    Energy Technology Data Exchange (ETDEWEB)

    Goma i Huguet, A.; Quintana i Comte, J.; Soler i Vilaro, J.

    2005-07-01

    Recreational water like the present in swimming pools suffers, more than water from supply, formation of certain by-products in the local disinfection system because a mechanism of accumulation. Using advanced oxidation process, like onization, drives to a reduction of such an effect. Assessment of the presence of these disinfection by-products with and without onization, as well as the discussion of certain key aspects of how to ozonate, are the aim of this paper. (Author) 7 refs.

  3. Digestion kinetics of carbohydrate fractions of citrus by-products

    OpenAIRE

    Lashkari, Saman; Taghizadeh, Akbar

    2015-01-01

    The present experiment was carried out to determine the digestion kinetics of carbohydrate fractions of citrus by-products. Grapefruit pulp (GP), lemon pulp (LE), lime pulp (LI) and orange pulp (OP) were the test feed. Digestion kinetic of whole citrus by-products and neutral detergent fiber (NDF) fraction and acid detergent fiber (ADF) fractions of citrus by-products were measured using the in vitro gas production technique. Fermentation kinetics of the neutral detergent soluble carbohydrate...

  4. Alarming atmospheres

    DEFF Research Database (Denmark)

    Højlund, Marie; Kinch, Sofie

    2014-01-01

    Nurses working in the Neuro-Intensive Care Unit at Aarhus University Hospital lack the tools to prepare children for the alarming atmosphere they will enter when visiting a hospitalised relative. The complex soundscape dominated by alarms and sounds from equipment is mentioned as the main stressor...

  5. Atmospheric humidity

    Science.gov (United States)

    Water vapor plays a critical role in earth's atmosphere. It helps to maintain a habitable surface temperature through absorption of outgoing longwave radiation, and it transfers trmendous amounts of energy from the tropics toward the poles by absorbing latent heat during evaporation and subsequently...

  6. Atmospheric and aerosol chemistry

    Energy Technology Data Exchange (ETDEWEB)

    McNeill, V. Faye [Columbia Univ., New York, NY (United States). Dept. of Chemical Engineering; Ariya, Parisa A. (ed.) [McGill Univ. Montreal, QC (Canada). Dept. of Chemistry; McGill Univ. Montreal, QC (Canada). Dept. of Atmospheric and Oceanic Sciences

    2014-09-01

    This series presents critical reviews of the present position and future trends in modern chemical research. Short and concise reports on chemistry, each written by the world renowned experts. Still valid and useful after 5 or 10 years. More information as well as the electronic version of the whole content available at: springerlink.com. Christian George, Barbara D'Anna, Hartmut Herrmann, Christian Weller, Veronica Vaida, D. J. Donaldson, Thorsten Bartels-Rausch, Markus Ammann Emerging Areas in Atmospheric Photochemistry. Lisa Whalley, Daniel Stone, Dwayne Heard New Insights into the Tropospheric Oxidation of Isoprene: Combining Field Measurements, Laboratory Studies, Chemical Modelling and Quantum Theory. Neil M. Donahue, Allen L. Robinson, Erica R. Trump, Ilona Riipinen, Jesse H. Kroll Volatility and Aging of Atmospheric Organic Aerosol. P. A. Ariya, G. Kos, R. Mortazavi, E. D. Hudson, V. Kanthasamy, N. Eltouny, J. Sun, C. Wilde Bio-Organic Materials in the Atmosphere and Snow: Measurement and Characterization V. Faye McNeill, Neha Sareen, Allison N. Schwier Surface-Active Organics in Atmospheric Aerosols.

  7. Atmospheric gas phase reactions

    Science.gov (United States)

    Platt, Ulrich

    This chapter introduces the underlying physicochemical principles and the relevance of atmospheric gas phase reactions. In particular, reaction orders, the concept of elementary reactions, definition of and factors determining reaction rates (kinetic theory of chemical reactions), and photochemical reactions are discussed. Sample applications of the pertinent reaction pathways in tropospheric chemistry are presented, particularly reactions involving free radicals (OH, NO3, halogen oxides) and their roles in the self-cleaning of the troposphere. The cycles of nitrogen and sulfur species as well as the principles of tropospheric ozone formation are introduced. Finally, the processes governing the stratospheric ozone layer (Chapman Cycle and extensions) are discussed.

  8. 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

  9. 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

    2016-03-01

    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 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 Ångström 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

  10. 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.; van Donkelaar, Aaron; Buchard, Virginie; Torres, Omar; Ridley, David A.; Spurr, Robert J. D.

    2016-03-01

    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 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 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 Ångström 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

  11. High-Performance Zinc Tin Oxide Semiconductor Grown by Atmospheric-Pressure Mist-CVD and the Associated Thin-Film Transistor Properties.

    Science.gov (United States)

    Park, Jozeph; Oh, Keun-Tae; Kim, Dong-Hyun; Jeong, Hyun-Jun; Park, Yun Chang; Kim, Hyun-Suk; Park, Jin-Seong

    2017-06-21

    Zinc tin oxide (Zn-Sn-O, or ZTO) semiconductor layers were synthesized based on solution processes, of which one type involves the conventional spin coating method and the other is grown by mist chemical vapor deposition (mist-CVD). Liquid precursor solutions are used in each case, with tin chloride and zinc chloride (1:1) as solutes in solvent mixtures of acetone and deionized water. Mist-CVD ZTO films are mostly polycrystalline, while those synthesized by spin-coating are amorphous. Thin-film transistors based on mist-CVD ZTO active layers exhibit excellent electron transport properties with a saturation mobility of 14.6 cm(2)/(V s), which is superior to that of their spin-coated counterparts (6.88 cm(2)/(V s)). X-ray photoelectron spectroscopy (XPS) analyses suggest that the mist-CVD ZTO films contain relatively small amounts of oxygen vacancies and, hence, lower free-carrier concentrations. The enhanced electron mobility of mist-CVD ZTO is therefore anticipated to be associated with the electronic band structure, which is examined by X-ray absorption near-edge structure (XANES) analyses, rather than the density of electron carriers.

  12. The Effect of MnO2 Content and Sintering Atmosphere on The Electrical Properties of Iron Titanium Oxide NTC Thermistors using Yarosite

    Science.gov (United States)

    Wiendartun; Gustaman Syarif, Dani

    2017-02-01

    The effect of MnO2 content and sintering atmosphere on the characteristics of Fe2TiO5 ceramics for Negative Thermal Coefficient (NTC) thermistors by using Fe2O3 derived from yarosite has been studied. The ceramics were produced by pressing a homogeneous mixture of Fe2O3, TiO2 and MnO2 (0-2.0 w/o) powders in appropriate proportions to produce Fe2TiO5 based ceramics and sintering the pressed powder at 1100-1200°C for 3 hours in air, O2 and N2 gas. Electrical characterization was done by measuring electrical resistivity of the sintered ceramics at various temperatures from 30°C to 200°C. Microstructure and structural analyses were also carried out by using an scanning electron microscope (SEM) and x-ray diffraction (XRD). The XRD data showed that the pellets crystallize in orthorhombic. The presence of second phase could not be identified from the XRD analyses. The SEM images showed that the grain size of pellet ceramics increase with increasing of MnO2 addition, and the grains size of the ceramic sintered in oxygen gas is smaller than sintered in nitrogen gas. Electrical data showed that the value of room temperature resistance (RRT) tend to decrease with respect to the increasing of MnO2 addition and the pellet ceramics sintered in oxygen gas had the largest thermistor constant (B), activation energy (Ea), sensitivity (α) and room temperature resistance (RRT), compared to the sintered in nitrogen gas. From the electrical characteristics data, it was known that the electrical characteristics of the Fe2TiO5 pellet ceramics followed the NTC characteristic. The fabricated Fe2TiO5 ceramics have thermistor constants (B = 2207-7145K). This can be applied as temperature sensor, and will fulfill the market requirement.

  13. Atmospheric materiality

    DEFF Research Database (Denmark)

    Wieczorek, Izabela

    2016-01-01

    A disjunction between the material and the immaterial has been at the heart of the architectural debate for decades. In this dialectic tension, the notion of atmosphere which increasingly claims attention in architectural discourse seems to be parallactic, leading to the re-evaluation of perceptual...... experience and, consequently, to the conceptual and methodological shifts in the production of space, and hence in the way we think about materiality. In this context, architectural space is understood as a contingent construction – a space of engagement that appears to us as a result of continuous...... and complex interferences revealed through our perception; ‘the atmospheric’ is explored as a spatial and affective quality as well as a sensory background, and materiality as a powerful and almost magical agency in shaping of atmosphere. Challenging existing dichotomies and unraveling intrinsic...

  14. Middle Atmosphere Program. Handbook for MAP. Volume 13: Ground-based Techniques

    Science.gov (United States)

    Vincent, R. A. (Editor)

    1984-01-01

    Topics of activities in the middle Atmosphere program covered include: lidar systems of aerosol studies; mesosphere temperature; upper atmosphere temperatures and winds; D region electron densities; nitrogen oxides; atmospheric composition and structure; and optical sounding of ozone.

  15. 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.

  16. 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.

  17. 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.

  18. 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.

  19. Evolution of the atmosphere.

    Science.gov (United States)

    Nunn, J F

    1998-01-01

    Planetary atmospheres depend fundamentally upon their geochemical inventory, temperature and the ability of their gravitational field to retain gases. In the case of Earth and other inner planets, early outgassing released mainly carbon dioxide and water vapour. The secondary veneer of comets and meteorites added further volatiles. Photodissociation caused secondary changes, including the production of traces of oxygen from water. Earth's gravity cannot retain light gases, including hydrogen. but retains oxygen. Water vapour generally does not pass the cold trap at the stratopause. In the archaean, early evolution of life, probably in hydrothermal vents, and the subsequent development of photosynthesis in surface waters, produced oxygen, at 3500 Ma or even earlier, becoming a significant component of the atmosphere from about 2000 Ma. Thereafter banded iron formations became rare, and iron was deposited in oxidized red beds. Atmospheric levels of carbon dioxide and oxygen have varied during the Phanerozoic: major changes may have caused extinctions. particularly the Permian/Triassic. The declining greenhouse effect due to the long-term decrease in carbon dioxide has largely offset increasing solar luminosity, and changes in carbon dioxide levels relate strongly to cycles of glaciation.

  20. Aqueous chlorination of acebutolol: kinetics, transformation by-products, and mechanism.

    Science.gov (United States)

    Khalit, Wan Nor Adira Wan; Tay, Kheng Soo

    2016-02-01

    This study investigated the reaction kinetics and the transformation by-products of acebutolol during aqueous chlorination. Acebutolol is one of the commonly used β-blockers for the treatment of cardiovascular diseases. It has been frequently detected in the aquatic environment. In the kinetics study, the second-order rate constant for the reaction between acebutolol and chlorine (k app) was determined at 25 ± 0.1 °C. The degradation of acebutolol by free available chlorine was highly pH dependence. When the pH increased from 6 to 8, it was found that the k app for the reaction between acebutolol and free available chlorine was increased from 1.68 to 11.2 M(-1) min(-1). By comparing with the reported k app values, the reactivity of acebutolol toward free available chlorine was found to be higher than atenolol and metoprolol but lower than nadolol and propranolol. Characterization of the transformation by-products formed during the chlorination of acebutolol was carried out using liquid chromatography-quadrupole time-of-flight high-resolution mass spectrometry. Seven major transformation by-products were identified. These transformation by-products were mainly formed through dealkylation, hydroxylation, chlorination, and oxidation reactions.

  1. Utilization of low rank coal and agricultural by-products

    Energy Technology Data Exchange (ETDEWEB)

    Ekinci, E.; Yardim, M.F.; Petrova, B.; Budinova, T.; Petrov, N. [Istanbul Technical University, Maslak-Istanbul (Turkey). Department of Chemical Engineering

    2007-07-01

    The present investigation deals with alternative utilization processes to convert low rank coal and agricultural by products into solid, liquid and gaseous products for a more efficient exploitation of these materials. Low rank coals and different agricultural by-products were subjected to different thermochemical treatments. The composition and physico-chemical properties of liquid products obtained from agricultural by-products were investigated. The identified compounds are predominantly oxygen derivatives of phenol, dihydroxybenzenes, guaiacol, syringol, vanilin, veratrol, furan and acids. Liquids from low rank coals contain higher quality of aromatic compounds predominantly mono- and bicyclic. The amount of oxygen containing structures is high as well. By thermo-chemical treatment of liquid products from agricultural by-products, low rank coals and their mixtures with H{sub 2}SO{sub 4} carbon adsorbents with very low ash and sulfur content are obtained. Using different activation reagents large scale carbon adsorbents are prepared from agricultural by-products and coals. The results of the investigations open-up possibilities for utilization of low rank coals and agricultural by-products. 18 refs., 5 figs., 7 tabs.

  2. Microstructural evaluation of ceria-samaria-gadolinia-nickel oxide composite after reduction in hydrogen atmosphere; Avaliacao microestrutural do composito de ceria-samaria-gadolinia-oxido de niquel apos reducao em atmosfera de hidrogenio

    Energy Technology Data Exchange (ETDEWEB)

    Arakaki, A. R.; Yoshito, W.K.; Ussui, V.; Lazar, D.R.R., E-mail: alexander@ipen.br [Instituto de Pesquisas Energeticas e Nucleares (IPEN/CNEN-SP), Sao Paulo, SP (Brazil)

    2012-07-01

    The ceria-samaria-gadolinia-nickel composite (Ni-SGDC), used as Solid Oxide Fuel Cell (SOFC) anode, was obtained by 'in situ' reduction of NiO-SGDC, with composition Ce{sub 0,8}(SmGd){sub 0,2}O{sub 1,9}/NiO and mass proportion 40:60%. The composite was produced by hydroxides coprecipitation using CTAB surfactant, followed by solvothermal treatment in butanol, calcination at 600 deg C, pressing and sintering at 1350 deg C for 1 h. The composite reduction kinetic was evaluated in a tubular furnace under dynamic atmosphere of 4% H2 /Air, fixing the temperature at 900 deg C and time between 10 and 120 minutes. The microstructural characterization was performed by optical and scanning electron microscopy. The samples were characterized either by X-ray diffraction and density measurements by immersion technique in water. It was verified that the NiO reduced fraction reached values between 80 and 90% and the achieved porosity (about 30%) is acceptable to a good anode performance (author)

  3. 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...

  4. A theory of atmospheric oxygen.

    Science.gov (United States)

    Laakso, T A; Schrag, D P

    2017-05-01

    Geological records of atmospheric oxygen suggest that pO 2 was less than 0.001% of present atmospheric levels (PAL) during the Archean, increasing abruptly to a Proterozoic value between 0.1% and 10% PAL, and rising quickly to modern levels in the Phanerozoic. Using a simple model of the biogeochemical cycles of carbon, oxygen, sulfur, hydrogen, iron, and phosphorous, we demonstrate that there are three stable states for atmospheric oxygen, roughly corresponding to levels observed in the geological record. These stable states arise from a series of specific positive and negative feedbacks, requiring a large geochemical perturbation to the redox state to transition from one to another. In particular, we show that a very low oxygen level in the Archean (i.e., 10 -7 PAL) is consistent with the presence of oxygenic photosynthesis and a robust organic carbon cycle. We show that the Snowball Earth glaciations, which immediately precede both transitions, provide an appropriate transient increase in atmospheric oxygen to drive the atmosphere either from its Archean state to its Proterozoic state, or from its Proterozoic state to its Phanerozoic state. This hypothesis provides a mechanistic explanation for the apparent synchronicity of the Proterozoic Snowball Earth events with both the Great Oxidation Event, and the Neoproterozoic oxidation. © 2017 John Wiley & Sons Ltd.

  5. 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...

  6. Contribution of anthropogenic and natural sources to atmospheric methane variability

    NARCIS (Netherlands)

    Bousquet, P.; Ciais, P.; Miller, J.B.; Dlugokencky, E.J.; Hauglustaine, D.A.; Prigent, C.; van der Werf, G.R.; Peylin, P.; Brunke, E.G.; Carouge, C.; Langenfelds, R.L.; Lathiere, J.; Papa, F.; Ramonet, M.; Schmidt, M.; Steele, L.P.; Tyler, S.C.; White, J.

    2006-01-01

    Methane is an important greenhouse gas, and its atmospheric concentration has nearly tripled since pre-industrial times. The growth rate of atmospheric methane is determined by the balance between surface emissions and photochemical destruction by the hydroxyl radical, the major atmospheric oxidant.

  7. Satellite Observations of Atmospheric Halogen Oxides

    OpenAIRE

    Wagner, Thomas

    1999-01-01

    Die große Bedeutung von Halogenverbindungen bezüglich der Zerstörung atmosphärischen Ozons wurde schlagartig offenbar, als Mitte der Achtziger Jahre ein dramatischer Ozonverlust über der Antarktis beobachtet wurde, seither bekannt als Ozonloch. Während der folgenden Jahre konnten reaktive Halogenverbindungen auch in der Troposphäre nachgewiesen werden. Seit der Entdeckung des Ozonlochs erweiterte sich das Wissen der atmosphärischen Halogenchemie deutlich; hierzu trugen unter anderem auch abso...

  8. Monitoring natural organic matter and disinfection by-products at ...

    African Journals Online (AJOL)

    Natural organic matter (NOM) is a complex organic material present in natural surface water. NOM can cause problems during water treatment . most notably the formation of toxic disinfection by-products. This study was undertaken in order to assess the effectiveness of some of the water treatment techniques employed by ...

  9. 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.

  10. 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.

  11. Pathway engineering of Enterobacter aerogenes to improve acetoin production by reducing by-products formation.

    Science.gov (United States)

    Jang, Ji-Woong; Jung, Hwi-Min; Im, Dae-Kyun; Jung, Moo-Young; Oh, Min-Kyu

    2017-11-01

    Enterobacter aerogenes was metabolically engineered for acetoin production. To remove the pathway enzymes that catalyzed the formation of by-products, the three genes encoding a lactate dehydrogenase (ldhA) and two 2,3-butanediol dehydrogenases (budC, and dhaD), respectively, were deleted from the genome. The acetoin production was higher under highly aerobic conditions. However, an extracellular glucose oxidative pathway in E. aerogenes was activated under the aerobic conditions, resulting in the accumulation of 2-ketogluconate. To decrease the accumulation of this by-product, the gene encoding a glucose dehydrogenase (gcd) was also deleted. The resulting strain did not produce 2-ketogluconate but produced significant amounts of acetoin, with concentration reaching 71.7g/L with 2.87g/L/h productivity in fed-batch fermentation. This result demonstrated the importance of blocking the glucose oxidative pathway under highly aerobic conditions for acetoin production using E. aerogenes. Copyright © 2017 Elsevier Inc. All rights reserved.

  12. Solar photocatalytic oxidation of recalcitrant natural metabolic by-products of amoxicillin biodegradation.

    Science.gov (United States)

    Pereira, João H O S; Reis, Ana C; Homem, Vera; Silva, José A; Alves, Arminda; Borges, Maria T; Boaventura, Rui A R; Vilar, Vítor J P; Nunes, Olga C

    2014-11-15

    The contamination of the aquatic environment by non-metabolized and metabolized antibiotic residues has brought the necessity of alternative treatment steps to current water decontamination technologies. This work assessed the feasibility of using a multistage treatment system for amoxicillin (AMX) spiked solutions combining: i) a biological treatment process using an enriched culture to metabolize AMX, with ii) a solar photocatalytic system to achieve the removal of the metabolized transformation products (TPs) identified via LC-MS, recalcitrant to further biological degradation. Firstly, a mixed culture (MC) was obtained through the enrichment of an activated sludge sample collected in an urban wastewater treatment plant (WWTP). Secondly, different aqueous matrices spiked with AMX were treated with the MC and the metabolic transformation products were identified. Thirdly, the efficiency of two solar assisted photocatalytic processes (TiO2/UV or Fe(3+)/Oxalate/H2O2/UV-Vis) was assessed in the degradation of the obtained TPs using a lab-scale prototype photoreactor equipped with a compound parabolic collector (CPC). Highest AMX specific biodegradation rates were obtained in buffer and urban wastewater (WW) media (0.10 ± 0.01 and 0.13 ± 0.07 g(AMX) g(biomass)(-1) h(-1), respectively). The resulting TPs, which no longer presented antibacterial activity, were identified as amoxicilloic acid (m/z = 384). The performance of the Fe(3+)/Oxalate/H2O2/UV-Vis system in the removal of the TPs from WW medium was superior to the TiO2/UV process (TPs no longer detected after 40 min (QUV = 2.6 kJ L(-1)), against incomplete TPs removal after 240 min (QUV = 14.9 kJ L(-1)), respectively). Copyright © 2014 Elsevier Ltd. All rights reserved.

  13. Economical Recovery of By-products in the Mining Industry

    Energy Technology Data Exchange (ETDEWEB)

    Berry, J.B.

    2001-12-05

    The U.S. Department of Energy (DOE) Office of Industrial Technologies, Mining Industry of the Future Program, works with the mining industry to further the industry's advances toward environmental and economic goals. Two of these goals are (1) responsible emission and by-product management and (2) low-cost and efficient production (DOE 1998). DOE formed an alliance with the National Mining Association (NMA) to strengthen the basis for research projects conducted to benefit the mining industry. NMA and industry representatives actively participate in this alliance by evaluating project proposals and by recommending research project selection to DOE. Similarly, the National Research Council (NRC) has recently and independently recommended research and technology development opportunities in the mining industry (NRC 2001). The Oak Ridge National Laboratory (ORNL) and Colorado School of Mines engineers conducted one such project for DOE regarding by -product recovery from mining process residue. The results of this project include this report on mining industry process residue and waste with opportunity for by-product recovery. The U.S. mineral processing industry produces over 30,000,000 metric tons per year of process residue and waste that may contain hazardous species as well as valuable by-products. This study evaluates the copper, lead, and zinc commodity sectors which generate between 23,300,000 and 24,000,000 metric tons per year. The distribution of residual elements in process residues and wastes varies over wide ranges* because of variations in the original ore content as it is extracted from the earth's crust. In the earth's crust, the elements of interest to mining fall into two general geochemical classifications, lithophiles and chalcophiles** (Cox 1997). Groups of elements are almost always present together in a given geochemical classification, but the relative amounts of each element are unique to a particular ore body. This paper

  14. Steam reforming of biodiesel by-product to make renewable hydrogen.

    Science.gov (United States)

    Slinn, Matthew; Kendall, Kevin; Mallon, Christian; Andrews, James

    2008-09-01

    The aim of this paper was to investigate the viability of steam reforming the combined glycerol and water by-product streams of a biodiesel plant. A platinum alumina catalyst was used to optimise the operating conditions for glycerol steam reforming and mass spectroscopy was chosen to measure reformer gas yield. The problem is that glycerol steam reforming is relatively untested even with pure glycerol and the by-product quality may be too poor. The strategy was therefore to optimise the process using pure glycerol and compare the performance with by-product glycerol. To test catalyst degradation caused by carbon deposition, a Solid Oxide fuel cell (SOFC) was used as a separate reformer and electrical performance was measured to indicate carbon deposition. This is the first time a SOFC has been run on glycerol. The results showed that thermodynamic theory can be used to predict reformer performance. At high temperatures high gas yield can be reached (almost 100%) and selectivities of 70% (dry basis) obtained. The optimum conditions for glycerol reforming were 860 degrees C temperature (maximum tested), 0.12 mols/min glycerol flow per kg of catalyst and 2.5 steam/carbon ratio. Reforming catalysts lasted for several days of continuous operation with minimal degradation, 0.4% of feed deposited. By-product glycerol performed slightly worse with a lower yield and more carbon deposition, 2% of feed. The results show that glycerol steam reforming is a viable alternative use for glycerol and potentially a better option than purification.

  15. 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...

  16. By-product information can stabilize the reliability of communication.

    Science.gov (United States)

    Schaefer, H Martin; Ruxton, G D

    2012-12-01

    Although communication underpins many biological processes, its function and basic definition remain contentious. In particular, researchers have debated whether information should be an integral part of a definition of communication and how it remains reliable. So far the handicap principle, assuming signal costs to stabilize reliable communication, has been the predominant paradigm in the study of animal communication. The role of by-product information produced by mechanisms other than the communicative interaction has been neglected in the debate on signal reliability. We argue that by-product information is common and that it provides the starting point for ritualization as the process of the evolution of communication. Second, by-product information remains unchanged during ritualization and enforces reliable communication by restricting the options for manipulation and cheating. Third, this perspective changes the focus of research on communication from studying signal costs to studying the costs of cheating. It can thus explain the reliability of signalling in many communication systems that do not rely on handicaps. We emphasize that communication can often be informative but that the evolution of communication does not cause the evolution of information because by-product information often predates and stimulates the evolution of communication. Communication is thus a consequence but not a cause of reliability. Communication is the interplay of inadvertent, informative traits and evolved traits that increase the stimulation and perception of perceivers. Viewing communication as a complex of inadvertent and derived traits facilitates understanding of the selective pressures shaping communication and those shaping information and its reliability. This viewpoint further contributes to resolving the current controversy on the role of information in communication. © 2012 The Authors. Journal of Evolutionary Biology © 2012 European Society For Evolutionary

  17. Water disinfection agents and disinfection by-products

    Science.gov (United States)

    Ilavský, J.; Barloková, D.; Kapusta, O.; Kunštek, M.

    2017-10-01

    The aim of this work is to describe factors of water quality change in the distribution network and legislative requirements in Slovakia for disinfectants and disinfection byproducts (DBPs). In the experimental part, the time dependence of the application of the chlorine dioxide and sodium hypochlorite on the formation of some by-products of disinfection for drinking water from WTP Hriňová is studied. We monitored trihalomethanes, free chlorine, chlorine dioxide and chlorites.

  18. Boron availability to plants from coal combustion by-products

    Energy Technology Data Exchange (ETDEWEB)

    Kukier, U.; Sumner, M.E. [University of Georgia, Athens, GA (United States). Dept. of Crop and Soil Sciences

    1996-02-01

    Agronomic use of coal combustion by-products is often associated with boron (B) excess in amended soils and subsequently in plants. A greenhouse study with corn ({ital Zea mays L.}) as test plant was conducted to determine safe application rates of five fly ashes and one flue gas desulfurization gypsum (FDG). All by-products increased soil and corn tissue B concentration, in some cases above toxicity levels which are 5 mg hot water soluble B (hwsB)kg{sup -1} soil and 100 mg B kg{sup -1} in corn tissue. Acceptable application rates varied from 4 to 100 Mg ha{sup -1} for different by-products. Leaching and weathering of a high B fly ash under ponding conditions decreased its B content and that of corn grown in fly ash amended soil, while leaching of the same fly ash under laboratory conditions increased fly ash B availability to corn in comparison to the fresh fly ash. Hot water soluble B in fly ash or FDG amended soil correlated very well with corn tissue B. Hot water soluble B in fly ash amended soil could be predicted based on soil pH and B solubility in ash at different pH values but not so in the case of FDG. Another greenhouse study was conducted to compare the influence of FDG and Ca(OH{sub 2}) on B concentration in spinach ({ital Spinacia oleracea L.}) leaves grown in soil amended with the high B fly ash. The Ca(OH){sub 2} significantly decreased tissue B content, while FDG did not affect B uptake from fly ash amended soil. 41 refs., 6 figs., 5 tabs.

  19. Controlled decomposition and oxidation: A treatment method for gaseous process effluents

    Science.gov (United States)

    Mckinley, Roger J. B., Sr.

    1990-01-01

    The safe disposal of effluent gases produced by the electronics industry deserves special attention. Due to the hazardous nature of many of the materials used, it is essential to control and treat the reactants and reactant by-products as they are exhausted from the process tool and prior to their release into the manufacturing facility's exhaust system and the atmosphere. Controlled decomposition and oxidation (CDO) is one method of treating effluent gases from thin film deposition processes. CDO equipment applications, field experience, and results of the use of CDO equipment and technological advances gained from the field experiences are discussed.

  20. Biogas from by-products; Biogas aus Nebenprodukten

    Energy Technology Data Exchange (ETDEWEB)

    Mack, Andreas [Eisenmann Anlagenbau GmbH und Co. KG, Boeblingen (Germany)

    2013-01-15

    The Italian sugar producer Co.Pro.B. (Minerbio, Italy) looked for an industrially experienced plant engineer for the biogas process in order to utilize energetically the by-products from the processing of sugar beets. Co.Pro.B. found the German environmental technology specialist Eisenmann Anlagenbau GmbH and Co. KG (Boeblingen, Federal Republic of Germany). After a planning and building period of only six months, even three biogas plants with plug-flow fermentation were brought on line in the provinces Bologna and Padua in autumn 2012.

  1. Utilization of Biodiesel By-Products for Biogas Production

    Science.gov (United States)

    Kolesárová, Nina; Hutňan, Miroslav; Bodík, Igor; Špalková, Viera

    2011-01-01

    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. PMID:21403868

  2. Utilization of Chicken By-Products to Form Collagen Films

    Directory of Open Access Journals (Sweden)

    Kumudini A. Munasinghe

    2015-01-01

    Full Text Available Chicken collagen casings could be an alternate source of collagen casings that are manufactured for sausages. The overall objective of this project was to extract chicken collagen from by-products of the broiler processing industries and to explore the possibility of making films. Chicken skin was washed, ground, and pretreated to remove the noncollagenous compounds. Collagen was extracted using acetic acid and pepsin. Solubilized collagen was salted-out and centrifuged at 20,000 ×g at 4°C for one hour. The precipitates were dissolved in 0.5 M acetic acid and dialyzed against 0.1 M acetic acid and distilled water before freeze-drying. Molecular weight, collagen solubility at different pH values, and NaCl concentrations were determined. TA-XT2 texture analyzer was used to characterize mechanical properties of collagen films. The highest collagen solubility was obtained at pH 2 and 2% NaCl. Hand-homogenized, nonfiltered, and conditioned samples had the highest hardness (3,262 g and the least brittleness (30.5 mm. These results demonstrate that chicken collagen extracted from chicken by-products has the ability to form films and could be considered for making casings or be used in various other industries.

  3. Wheat bread biofortification with rootlets, a malting by-product.

    Science.gov (United States)

    Waters, Deborah M; Kingston, Wilma; Jacob, Fritz; Titze, Jean; Arendt, Elke K; Zannini, Emanuele

    2013-08-15

    Barley rootlets, a malting by-product, are currently discarded or used as fodder. In this study, milled rootlets and Lactobacillus plantarum FST 1.7-fermented rootlets were incorporated into wheat bread. The objective was to formulate a high-nutrition alternative to wholemeal breads with improved technological attributes. Chemical analyses showed that rootlets contribute nutrients and bioactive compounds, including proteins, amino acids, fatty acids, carbohydrates, dietary fibre, polyphenols and minerals. Rootlets are particularly rich in essential amino acids, especially lysine, the typically limiting essential amino acid of cereals. Additionally, rootlets offer potential dietary fibre health benefits such as protection against cardiovascular disease, cancers and digestive disorders. Breads prepared with a (fermented) rootlet inclusion level of up to 10% compared favourably with wholemeal breads from nutritive, technological and textural perspectives. Furthermore, they were well accepted by sensory panellists. Using rootlets as a food ingredient would have the added benefit of increasing this malting by-product's market value. © 2013 Society of Chemical Industry.

  4. Atmosphere: Power, Critique, Politics

    DEFF Research Database (Denmark)

    Albertsen, Niels

    2016-01-01

    This paper hans three interrelated parts. First, atmosphere is approached through the concept of power. Atmospheres 'grip' us directly or mediate power indirectly by manipulating moods and evoking emotions. How does atmosphere relate to different conceptions of power? Second, atmospheric powers may...

  5. Aqueous photodegradation of 4-tert-butylphenol: By-products, degradation pathway and theoretical calculation assessment

    Energy Technology Data Exchange (ETDEWEB)

    Wu, Yanlin [State Key Laboratory of Pollution Control and Resources Reuse, College of Environmental Science and Engineering, Tongji University, Shanghai 200092 (China); Shi, Jin; Chen, Hongche [Shanghai Key Laboratory of Atmospheric Particle Pollution and Prevention, Department of Environmental Science & Engineering, Fudan University, Shanghai 200433 (China); Zhao, Jianfu [State Key Laboratory of Pollution Control and Resources Reuse, College of Environmental Science and Engineering, Tongji University, Shanghai 200092 (China); Dong, Wenbo, E-mail: wbdong@fudan.edu.cn [Shanghai Key Laboratory of Atmospheric Particle Pollution and Prevention, Department of Environmental Science & Engineering, Fudan University, Shanghai 200433 (China)

    2016-10-01

    4-tert-butylphenol (4-t-BP), an endocrine disrupting chemical, is widely distributed in natural bodies of water but is difficult to biodegrade. In this study, we focused on the transformation of 4-t-BP in photo-initiated degradation processes. The steady-state photolysis and laser flash photolysis (LFP) experiments were conducted in order to elucidate its degradation mechanism. Identification of products was performed using the GC–MS, LC-MS and theoretical calculation techniques. The oxidation pathway of 4-t-BP by hydroxyl radical (HO·) was also studied and H{sub 2}O{sub 2} was added to produce HO·. 4-tert-butylcatechol and 4-tert-butylphenol dimer were produced in 4-t-BP direct photolysis. 4-tert-butylcatechol and hydroquinone were produced by the oxidation of HO·. But the formation mechanism of 4-tert-butylcatechol in the two processes was different. The benzene ring was fractured in 4-t-BP oxidation process and 29% of TOC was degraded after 16 h irradiation. - Highlights: • Photodegradation of 4-t-BP, an endocrine disrupting chemical, has been investigated. • 3 stable byproducts were identified from photolysis and oxidation processes. • 5 transient by-products were concluded from LFP experiments. • The theoretical calculation was performed to confirm the byproducts. • 4-t-BP was degraded with increasing efficiency: 254 nm < H{sub 2}O{sub 2}/313 nm < H{sub 2}O{sub 2}/254 nm.

  6. 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

  7. Seasonal evaluation of disinfection by-products throughout two full-scale drinking water treatment plants.

    Science.gov (United States)

    Zhong, Xin; Cui, Chongwei; Yu, Shuili

    2017-07-01

    Carbonyl compounds can occur alpha-hydrogens or beta-diketones substitution reactions with disinfectants contributed to halogenated by-products formation. The objective of this research was to study the occurrence and fate of carbonyl compounds as ozonation by-products at two full-scale drinking water treatment plants (DWTPs) using different disinfectants for one year. The quality of the raw water used in both plants was varied according to the season. The higher carbonyl compounds concentrations were found in raw water in spring. Up to 15 (as the sum of both DWTPs) of the 24 carbonyl compounds selected for this work were found after disinfection. The dominant carbonyl compounds were formaldehyde, glyoxal, methyl-glyoxal, fumaric, benzoic, protocatechuic and 3-hydroxybenzoic acid at both DWTPs. In the following steps in each treatment plant, the concentration patterns of these carbonyl compounds differed depending on the type of disinfectant applied. Benzaldehyde was the only aromatic aldehyde detected after oxidation with ozone in spring. As compared with DWTP 1, five new carbonyl compounds were formed (crotonaldehyde, benzaldehyde, formic, oxalic and malonic acid) disinfection by ozone, and the levels of the carbonyl compounds increased. In addition, pre-ozonation (PO) and main ozonation (OZ) increased the levels of carbonyl compounds, however coagulation/flocculation (CF), sand filtration (SF) and granular activated carbon filtration (GAC) decreased the levels of carbonyl compounds. Copyright © 2017 Elsevier Ltd. All rights reserved.

  8. Evaluation of chlorinated by-products in drinking waters of Central Friuli (Italy).

    Science.gov (United States)

    Goi, Daniele; Tubaro, Franco; Barbone, Fabio; Dolcetti, Giuliano; Bontempelli, Gino

    2005-01-01

    Drinkable water supplied by aqueducts undergoes preliminar potabilization which, in Italy, is mainly accomplished by chlorine addition. The bactericidal action involved in this process is always accompanied by chlorination and oxidation of organic species (mainly humic and fulvic acids) naturally present in treated waters, so that many disinfection by-products (DBPs) are formed, such as trihalomethanes (THMs) and halo-acetic acids (HAA), which can represent a chemical risk for public health. The aim of this study was the monitoring of DBPs in drinking water disinfected by chlorination, supplied by four different aqueducts of Central Friuli (Italy). DBP evaluations were performed in water samples consisting of both input and output of disinfection plants. The results of analytical determinations were worked out to provide the THM and HAA parameters for disinfected waters, while in feeding waters the following different conventional parameters were adopted: (i) trihalomethanes formation potential (THMFP), (ii) halo-acetic acids formation potential (HAAFP) and (iii) UV absorbance at 254 nm (UV254). The quite moderate content of chlorinated products found in all samples considered highlighted the excellent quality of potabilized waters available in Central Friuli. Moreover, our results confirmed that the majority of DBPs formed when chlorine is used for water disinfection consists of THMs, while chlorites and chlorates prevailed when potabilization is accomplished by using chlorine dioxide. Finally, simple UV254 monitoring turned out to be a profitable approach for the determination of chlorinated by-products only when THMs prevail among DBPs.

  9. C/O atmosphere measurements

    Science.gov (United States)

    Kopytova, Taisiya

    2017-06-01

    The atmospheric carbon-to-oxygen ratio is believed to be a key to formation scenario of exoplanets. Due to different condensation temperatures for water, carbon oxide, and carbon dioxide, their "icelines" are situated at different parts of the protoplanetary disk resulting in different C/O ratio values through the disk. Therefore, by measuring a C/O ratio in the atmosphere of a giant exoplanet, we should be able to understand the planet's formation.I will give a brief overview of recent theoretical studies that predict how various mechanisms during planet formation (e.g. migration, pebble drift) may affect the feasability of using a C/O ratio to understand formation of exoplanets.In the second part of my talk, I will discuss various methods of measuring abundances in atmospheres. I will also talk about how to take into account systematic effects in observations and atmospheric models and if there is a possibility to determine and apply "C/O ratio indices".

  10. Photochemical processing of aqueous atmospheric brown carbon

    Directory of Open Access Journals (Sweden)

    R. Zhao

    2015-06-01

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

  11. Origin of disinfection by-products in cheese.

    Science.gov (United States)

    Cardador, Maria Jose; Gallego, Mercedes; Prados, Francisco; Fernández-Salguero, José

    2017-06-01

    The disinfection of water, equipment and surfaces in a cheese factory is one of the factors that can originate disinfection by-products (DBPs) in cheese. This research has focused on studying cheese factories in order to evaluate the individual contribution of each step of the cheese-making process that can contribute to the presence of DBPs in cheese. Ten factories were selected according to their salting processes (brine or dry salting). Each factory was monitored by the collection of six representative samples (factory water supply, brine solution, milk, whey, curd and cheese) in which the concentrations of up to eight chemicals were detected. The study shows that contact with brine solutions containing significant levels of DBPs is the main source of these chemicals in cheese. A minor factor is the pasteurised milk used in their manufacture.

  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. 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.)

  15. Atmospheric oxygenation three billion years ago

    DEFF Research Database (Denmark)

    Crowe, Sean; Døssing, Lasse Nørbye; Beukes, Nicolas J.

    2013-01-01

    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...

  16. Global Maps of Atmospheric Nitrogen Deposition, 1860, 1993, and 2050

    Data.gov (United States)

    National Aeronautics and Space Administration — This data set provides global gridded estimates of atmospheric deposition of total inorganic nitrogen (N), NHx (NH3 and NH4+), and NOy (all oxidized forms of...

  17. Global Maps of Atmospheric Nitrogen Deposition, 1860, 1993, and 2050

    Data.gov (United States)

    National Aeronautics and Space Administration — ABSTRACT: This data set provides global gridded estimates of atmospheric deposition of total inorganic nitrogen (N), NHx (NH3 and NH4+), and NOy (all oxidized forms...

  18. CARVE: L2 Atmospheric Gas Concentrations, Tower-based Flasks, Alaska, 2012-2015

    Data.gov (United States)

    National Aeronautics and Space Administration — This data set provides atmospheric carbon dioxide, methane, carbon monoxide, molecular hydrogen, nitrous oxide, sulfur hexafluoride, and other trace gas mole...

  19. Atmosphere-Ionosphere Coupling via Atmospheric Waves

    Science.gov (United States)

    Koucka Knizova, Petra; Lastovicka, Jan

    2017-04-01

    The Earth atmosphere and ionosphere is complicated and highly variable system which displays oscillations on wide range scales. The most important factor influencing the ionosphere is certainly the solar and geomagnetic activity. However, the processes even in distant regions in the neutral atmosphere cannot be simply neglected. This contribution reviews aspects of ionospheric variability originating in the lower laying atmosphere. It focuses especially on the generation and propagation of the atmospheric waves from their source region up to the heights of the ionosphere. We will show the role of infrasound, gravity waves, tides and planetary waves in the atmosphere-ionosphere coupling. Particularly gravity waves are of high importance for the ionosphere. Recent theoretical and experimental results will briefly be reviewed.

  20. CHARACTERIZATION OF COAL COMBUSTION BY-PRODUCTS FOR THE RE-EVOLUTION OF MERCURY INTO ECOSYSTEMS

    Energy Technology Data Exchange (ETDEWEB)

    J.A. Withum; J.E. Locke; S.C. Tseng

    2005-03-01

    There is concern that mercury (Hg) in coal combustion by-products might be emitted into the environment during processing to other products or after the disposal/landfill of these by-products. This perception may limit the opportunities to use coal combustion by-products in recycle/reuse applications and may result in additional, costly disposal regulations. In this program, CONSOL conducted a comprehensive sampling and analytical program to include ash, flue gas desulfurization (FGD) sludge, and coal combustion by-products. This work is necessary to help identify potential problems and solutions important to energy production from fossil fuels. The program objective was to evaluate the potential for mercury emissions by leaching or volatilization, to determine if mercury enters the water surrounding an active FGD disposal site and an active fly ash slurry impoundment site, and to provide data that will allow a scientific assessment of the issue. Toxicity Characteristic Leaching Procedure (TCLP) test results showed that mercury did not leach from coal, bottom ash, fly ash, spray dryer/fabric filter ash or forced oxidation gypsum (FOG) in amounts leading to concentrations greater than the detection limit of the TCLP method (1.0 ng/mL). Mercury was detected at very low concentrations in acidic leachates from all of the fixated and more than half of the unfixated FGD sludge samples, and one of the synthetic aggregate samples. Mercury was not detected in leachates from any sample when deionized water (DI water) was the leaching solution. Mercury did not leach from electrostatic precipitator (ESP) fly ash samples collected during activated carbon injection for mercury control in amounts greater than the detection limit of the TCLP method (1.0 ng/mL). Volatilization tests could not detect mercury loss from fly ash, spray dryer/fabric filter ash, unfixated FGD sludge, or forced oxidation gypsum; the mercury concentration of these samples all increased, possibly due to

  1. Superlubricating graphene and graphene oxide films

    Energy Technology Data Exchange (ETDEWEB)

    Sumant, Anirudha V.; Erdemir, Ali; Choi, Junho; Berman, Diana

    2018-02-13

    A system and method for forming at least one of graphene and graphene oxide on a substrate and an opposed wear member. The system includes graphene and graphene oxide formed by an exfoliation process or solution processing method to dispose graphene and/or graphene oxide onto a substrate. The system further includes an opposing wear member disposed on another substrate and a gas atmosphere of an inert gas like N2, ambient, a humid atmosphere and a water solution.

  2. 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. Copyright © 2015 Elsevier Ltd. All rights reserved.

  3. Atmospheric structure from Phoenix atmospheric entry data

    Science.gov (United States)

    Catling, D. C.

    2008-12-01

    The atmospheric structure at the time of landing of NASA's Phoenix probe has been derived from measurements of the aerodynamic drag of the spacecraft during atmospheric entry and descent. The result provides the first atmospheric structure in Mars' polar environment obtained from in situ measurements. Phoenix was equipped with an inertial measurement unit (IMU) that used accelerometers for linear acceleration measurement in three Cartesian axes and ring-laser gyroscopes to measure the three- dimensional orientation of the probe (Taylor et al., 2008). The temperature structure of the atmosphere along the flight path was calculated via a four-step process: (i) integrating forward the IMU data to obtain the time history of the spacecraft velocity vector relative to the atmosphere as a function of altitude; (ii) calculating atmospheric density from drag, with iteration for aerodynamic coefficient dependence on density; (iii) integrating the hydrostatic equation to derive the vertical pressure; and (iv) calculating atmospheric temperature from the equation of state. Initial profile reconstruction shows reasonable agreement with predictions in the middle atmosphere for the given season and time of day (landing occurred at 16h 33min 37sec in local solar time expressed as a 24-hour clock). However, the derived lower atmospheric structure below ~0.1 mbar is generally warmer than predicted. A possible explanation could be a shallower vertical distribution of dust that usually assumed. References: P. A. Taylor, D. C. Catling, M. Daly, C. S. Dickinson, H. O. Gunnlaugsson, A-M. Harri, C. F. Lange, Temperature, pressure and wind instrumentation on the Phoenix meteorological package, J. Geophys. Res., 113, EA0A10, doi:10.1029/2007JE003015, 2008.

  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. 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,...

  6. 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.

  7. 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.

  8. Synthesis of zeolite phases from combustion by-products

    Energy Technology Data Exchange (ETDEWEB)

    Pimraksa, K.; Chindaprasirt, P.; Setthaya, N. [Chiang Mai University, Chiang Mai (Thailand). Dept. of Industrial Chemistry

    2010-12-15

    Synthesis of zeolites from combustion by-products, including fly ash, bottom ash and rice husk ash, was studied. A molar ratio of SiO{sub 2}/Al2O{sub 3} of 1.5 was used for the syntheses. Refluxing and hydrothermal methods were also used for synthesis for comparison. The reaction temperatures of refluxing and hydrothermal methods were 100{sup o}C and 130{sup o}C, respectively. Sodalite, phillipsite-K, and zeolite P1 with analcime were obtained when fly ash, bottom ash and rice husk ash were used as starting materials, respectively. With rice husk ash as a starting material, zeolite P1 was produced. This result had advantages over previous studies as there was no prior activation required for the synthesis. The concentrations and types of alkaline used in the synthesis also determined the zeolite type. The different zeolites obtained from three systems were measured for specific surface area and pore size by using BET and Hg-porosimetry, respectively. Ammonium exchange capacities of the synthesised powders containing zeolites, sodalite, zeolite P1 and phillipsite-K were 38.5, 65.0 and 154.7 meq 100 g{sup 1}, respectively.

  9. 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.

  10. [Simulation of polluted atmospheres for animal experimentation: toxic gases].

    Science.gov (United States)

    Godin, J; Boudène, C

    1976-09-20

    A process for the generation of standardized polluted atmospheres usable for animal exposure is described. It is based on the diffusion of compressed gases across a silicone membrane. This device has been tested with four gases of particular importance in the field of atmospheric pollution (sulfur dioxide, nitrogen oxide, carbon monoxide and ammoniac).

  11. The effect of atmospheric corona treatment on AA1050 aluminium

    DEFF Research Database (Denmark)

    Jariyaboon, Manthana; Møller, Per; Dunin-Borkowski, Rafal E.

    2010-01-01

    The effect of atmospheric corona discharge on AM 050 aluminium surface was investigated using electrochemical polarization, SEM-EDX, FIB-SEM. and XPS. The corona treatment was performed with varying time (1, 5, and 15 min) in atmospheric air. A 200 nm oxide layer was generated on AA1050 after...

  12. Effect of surface morphology on atmospheric corrosion behaviour of ...

    Indian Academy of Sciences (India)

    Effect of surface morphology on atmospheric corrosion behaviour of Fe-based metallic glass, Fe67Co18Si14B1 ... present in atmospheric rust were analysed by X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FTIR) to be goethite, lepidocrocite, magnetite, cobalt oxide and cobalt hydroxide phases.

  13. 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

  14. Production of TEMPO by O atoms in atmospheric pressure non-thermal plasma–liquid interactions

    Science.gov (United States)

    Elg, Daniel T.; Yang, I.-Wei; Graves, David B.

    2017-11-01

    Non-thermal atmospheric pressure plasmas enable plasma treatment of surfaces without requiring a low-pressure environment. These plasmas are currently of interest for, among other things, their biomedical applications, many of which are enabled by production of reactive oxygen and nitrogen species (RONS). Plasma–liquid interactions are especially important due to the high amounts of water in biological materials. However, the chemistries of these plasmas are very complex and are not well-understood. One method to quantify plasma–liquid interactions is to dissolve a reactant into the liquid which, when exposed to plasma-created RONS, forms a measurable product. In particular, the oxidation of the spin trap TEMP to TEMPO has been used to track trends in reactive oxygen species. However, the effect of individual species on TEMP has not previously been determined. This paper differentiates the oxidation of TEMP due to various oxygen species produced by a He plasma jet operating in a controllable environment. Oxidation of TEMP is mainly to O atoms, with small or negligible contributions from other species. Thus, the TEMPO yield will also be used to illuminate trends in O atom production.

  15. 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.

  16. 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

  17. BUILDING MATERIALS MADE FROM FLUE GAS DESULFURIZATION BY-PRODUCTS

    Energy Technology Data Exchange (ETDEWEB)

    Michael W. Grutzeck; Maria DiCola; Paul Brenner

    2006-03-30

    Flue gas desulphurization (FGD) materials are produced in abundant quantities by coal burning utilities. Due to environmental restrains, flue gases must be ''cleaned'' prior to release to the atmosphere. They are two general methods to ''scrub'' flue gas: wet and dry. The choice of scrubbing material is often defined by the type of coal being burned, i.e. its composition. Scrubbing is traditionally carried out using a slurry of calcium containing material (slaked lime or calcium carbonate) that is made to contact exiting flue gas as either a spay injected into the gas or in a bubble tower. The calcium combined with the SO{sub 2} in the gas to form insoluble precipitates. Some plants have been using dry injection of these same materials or their own Class C fly ash to scrub. In either case the end product contains primarily hannebachite (CaSO{sub 3} {center_dot} 1/2H{sub 2}O) with smaller amounts of gypsum (CaSO{sub 4} {center_dot} 2H{sub 2}O). These materials have little commercial use. Experiments were carried out that were meant to explore the feasibility of using blends of hannebachite and fly ash mixed with concentrated sodium hydroxide to make masonry products. The results suggest that some of these mixtures could be used in place of conventional Portland cement based products such as retaining wall bricks and pavers.

  18. DEVELOPMENT OF ACTIVATED CARBONS FROM COAL COMBUSTION BY-PRODUCTS

    Energy Technology Data Exchange (ETDEWEB)

    Prof. Harold H. Schobert; Dr. M. Mercedes Maroto-Valer; Ms. Zhe Lu

    2002-09-27

    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, this report evaluates and compares several routes for the production of activated carbons from unburned carbon in fly ash, including physical and chemical activation methods. During the present reporting period (June 30, 2001-June 29, 2002), additional characterization work was conducted under Task 1 ''Procurement and characterization of CCBPs''. The suite collected includes samples from pulverized utility boilers, a utility cyclone unit equipped with a beneficiation technology, a stoker, and a fluidized bed combustor. Proximate, ultimate, and petrographic analyses of the fly ash samples previously collected were measured. Furthermore, the surface areas of the samples assembled were characterized by N{sub 2} adsorption isotherms at 77 K. The proximate analyses showed that all the samples had very low moisture contents (0.17 to 3.39 wt%), while volatile matter contents of the samples varied between 0.45 to 24.8 wt%. The ultimate analyses of all the fly ash samples showed that they contained primarily carbon, while the hydrogen contents of all the samples were very low. In addition, during the current reporting period, also Task 2 ''Development of activated carbons'' and Task 3 ''Characterization of activated carbons'' were continued.

  19. Atmospheric Habitable Zones in Y Dwarf Atmospheres

    Energy Technology Data Exchange (ETDEWEB)

    Yates, Jack S.; Palmer, Paul I. [School of GeoSciences, University of Edinburgh (United Kingdom); Biller, Beth; Cockell, Charles S., E-mail: j.s.yates@ed.ac.uk [Centre for Exoplanet Science, University of Edinburgh (United Kingdom)

    2017-02-20

    We use a simple organism lifecycle model to explore the viability of an atmospheric habitable zone (AHZ), with temperatures that could support Earth-centric life, which sits above an environment that does not support life. To illustrate our model, we use a cool Y dwarf atmosphere, such as WISE J085510.83–0714442.5, whose 4.5–5.2 μ m spectrum shows absorption features consistent with water vapor and clouds. We allow organisms to adapt to their atmospheric environment (described by temperature, convection, and gravity) by adopting different growth strategies that maximize their chance of survival and proliferation. We assume a constant upward vertical velocity through the AHZ. We found that the organism growth strategy is most sensitive to the magnitude of the atmospheric convection. Stronger convection supports the evolution of more massive organisms. For a purely radiative environment, we find that evolved organisms have a mass that is an order of magnitude smaller than terrestrial microbes, thereby defining a dynamical constraint on the dimensions of life that an AHZ can support. Based on a previously defined statistical approach, we infer that there are of the order of 10{sup 9} cool Y brown dwarfs in the Milky Way, and likely a few tens of these objects are within 10 pc from Earth. Our work also has implications for exploring life in the atmospheres of temperate gas giants. Consideration of the habitable volumes in planetary atmospheres significantly increases the volume of habitable space in the galaxy.

  20. Atmospheric Composition Change: Climate-Chemistry Interactions

    Science.gov (United States)

    Isaksen, I.S.A.; Granier, C.; Myhre, G.; Bernsten, T. K.; Dalsoren, S. B.; Gauss, S.; Klimont, Z.; Benestad, R.; Bousquet, P.; Collins, W.; hide

    2011-01-01

    Chemically active climate compounds are either primary compounds such as methane (CH4), removed by oxidation in the atmosphere, or secondary compounds such as ozone (O3), sulfate and organic aerosols, formed and removed in the atmosphere. Man-induced climate-chemistry interaction is a two-way process: Emissions of pollutants change the atmospheric composition contributing to climate change through the aforementioned climate components, and climate change, through changes in temperature, dynamics, the hydrological cycle, atmospheric stability, and biosphere-atmosphere interactions, affects the atmospheric composition and oxidation processes in the troposphere. Here we present progress in our understanding of processes of importance for climate-chemistry interactions, and their contributions to changes in atmospheric composition and climate forcing. A key factor is the oxidation potential involving compounds such as O3 and the hydroxyl radical (OH). Reported studies represent both current and future changes. Reported results include new estimates of radiative forcing based on extensive model studies of chemically active climate compounds such as O3, and of particles inducing both direct and indirect effects. Through EU projects such as ACCENT, QUANTIFY, and the AEROCOM project, extensive studies on regional and sector-wise differences in the impact on atmospheric distribution are performed. Studies have shown that land-based emissions have a different effect on climate than ship and aircraft emissions, and different measures are needed to reduce the climate impact. Several areas where climate change can affect the tropospheric oxidation process and the chemical composition are identified. This can take place through enhanced stratospheric-tropospheric exchange of ozone, more frequent periods with stable conditions favouring pollution build up over industrial areas, enhanced temperature-induced biogenic emissions, methane releases from permafrost thawing, and enhanced

  1. CHARACTERIZATION OF ENALAPRIL AND RANITIDINE CHLORINATION BY-PRODUCTS BY LIQUID CHROMATOGRAPHY/HIGH-RESOLUTION MASS SPECTROMETRY AND THEIR TOXICITY EVALUATION

    Directory of Open Access Journals (Sweden)

    Frederico Jehár Oliveira Quintão

    Full Text Available Due to its low cost, its capability for disinfection and oxidation, chlorination using gaseous chlorine or hypochlorite salts, has also been commonly applied in water treatment plants for oxidation and disinfection purposes. Little is known about the identity and toxicity of by-products resulting from the chlorination of pharmaceutical micropollutants, such as enalapril (ENA and ranitidine (RAN. ENA and RAN chlorination by-products were characterized in this study by high-performance liquid chromatography coupled to high-resolution mass spectrometry (HPLC/HRMS and their toxicity were assessed by MTT assay. Chlorination experiments with ENA and RAN solutions (10 mg L-1 indicate degradation efficiencies of 100% for both compounds after only 5 min of exposure to chlorine at concentration of 9.53 mg Cl2 L-1. On the other hand mineralization rates were lower than 3%, thereby indicating there was accumulation of degradation by-products in all experiments. Mass spectrometric analysis revealed, at all times of reaction after the addition of hypochlorite, the presence of 1-(2-((4-(chlorophenyl-1-ethoxy-1-oxobutan-2-ylaminopropanoylpyrrolidine-2-carboxylic acid (enalapril by-product and N-chloro-N-(2-(((chloro-5-((dimethylaminomethylfuran-2-ylmethylsulfinylethyl-N-methyl-2-nitroethene 1,1-diamine (ranitidine by-product. Despite the formation of oxidized chlorinated by-products in all chlorination assays, the treated solutions were nontoxic to HepG2 cells by the MTT assay. It has been observed that chlorination (10 mg L-1, 5 min of ENA and RAN solutions exhibited high degradation efficiencies of the target compounds and low mineralization rates. Based on the mass spectrometry data, the routes for ENA and RAN successive oxidation by chlorine has been proposed.

  2. 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)

  3. Enrichment of functional properties of ice cream with pomegranate by-products.

    Science.gov (United States)

    Çam, Mustafa; Erdoğan, Fatma; Aslan, Duygu; Dinç, Merve

    2013-10-01

    Pomegranate peel rich in phenolics, and pomegranate seed which contain a conjugated fatty acid namely punicic acid in lipid fraction remain as by-products after processing the fruit into juice. Ice cream is poor in polyunsaturated fatty acids and phenolics, therefore, this study was conducted to improve the functional properties of ice cream by incorporating pomegranate peel phenolics and pomegranate seed oil. Incorporation of the peel phenolics into ice cream at the levels of 0.1% and 0.4% (w/w) resulted in significant changes in the pH, total acidity, and color of the samples. The most prominent outcomes of phenolic incorporation were sharp improvements in antioxidant and antidiabetic activities as well as the phenolic content of ice creams. Replacement of pomegranate seed oil by milk fat at the levels of 2.0% and 4.0% (w/w) increased the conjugated fatty acid content. However, perception of oxidized flavor increased with the additional seed oil. When one considers the functional and nutritional improvements in the enrichment of the ice cream together with overall acceptability results of the sensory analysis, then it follows from this study that ice creams enriched with pomegranate peel phenolics up to 0.4% (w/w) and pomegranate seed oil up to 2.0% (w/w) could be introduced to markets as functional ice cream. Enrichment of ice creams with pomegranate by-products might provide consumers health benefits with striking functional properties of punicalagins in pomegranate peel, and punicic acid in pomegranate seed oil. © 2013 Institute of Food Technologists®

  4. Introductory lecture: atmospheric chemistry in the Anthropocene.

    Science.gov (United States)

    Finlayson-Pitts, Barbara J

    2017-08-24

    The term "Anthropocene" was coined by Professor Paul Crutzen in 2000 to describe an unprecedented era in which anthropogenic activities are impacting planet Earth on a global scale. Greatly increased emissions into the atmosphere, reflecting the advent of the Industrial Revolution, have caused significant changes in both the lower and upper atmosphere. Atmospheric reactions of the anthropogenic emissions and of those with biogenic compounds have significant impacts on human health, visibility, climate and weather. Two activities that have had particularly large impacts on the troposphere are fossil fuel combustion and agriculture, both associated with a burgeoning population. Emissions are also changing due to alterations in land use. This paper describes some of the tropospheric chemistry associated with the Anthropocene, with emphasis on areas having large uncertainties. These include heterogeneous chemistry such as those of oxides of nitrogen and the neonicotinoid pesticides, reactions at liquid interfaces, organic oxidations and particle formation, the role of sulfur compounds in the Anthropocene and biogenic-anthropogenic interactions. A clear and quantitative understanding of the connections between emissions, reactions, deposition and atmospheric composition is central to developing appropriate cost-effective strategies for minimizing the impacts of anthropogenic activities. The evolving nature of emissions in the Anthropocene places atmospheric chemistry at the fulcrum of determining human health and welfare in the future.

  5. [Hygienic assessment of drinking water chlorination by-products in view of multiroute exposure].

    Science.gov (United States)

    Egorova, N A; Bukshuk, A A; Krasovskiy, G N

    2013-01-01

    On the example of threstationary sampling points in houses of the Western Administrative District data on presence of trihalomethanes (TGM)--the main by-products of chlorination--in cold drinking and hot tap water of Moscow were analyzed. Since 'tthe middle of 2007 the concentration of chloroform and other TGM in tests of tap water were established to be defined at levels steadily below hygienic maximum concentration limits. In the performed experiments it is revealed that, despite rather low content of chloroform in water, when using a hot shower considerable receipt of substance in air of the bathing room--in the concentration exceeding average daily maximum concentration limit in atmospheric air is possible. In calculations by the three methods of chloroform doses which can influence the person in living conditions, inhalation receipt was shown to be less if compared with an peroral way (with drinking water) and absorption through skin appear and can make the greatest contribution to the general complex loading of chloroform.

  6. Spectroscopic Studies of Atmospheric Aerosol Chemistry

    Science.gov (United States)

    Wamsley, R.; Leather, K.; Horn, A. B.; Percival, C.

    2008-12-01

    Particles are ubiquitous in the troposphere and are involved in chemical and physical processes affecting the composition of the atmosphere, climate, cloud albedo and human health (Finlayson-Pitts and Pitts, 2000). Organic species, such as alcohols, carboxylic acids, ketones, aldehydes, aromatics, alkenes and alkanes, originate both from anthropogenic and natural sources and comprise a large component of atmospheric particles. Gas-phase species, such as ozone, can oxidize these organics, changing the particle's oxygen-to carbon ratio and potentially altering its hygroscopicity, viscosity, morphology and reactivity. One reaction in particular, that between ozone and oleic acid, has been the focus of several recent studies and extensively researched by Ziemann (2005). Oleic acid reacts readily with ozone and has a low vapor pressure making this reaction convenient to study in the laboratory and has become the benchmark for studying heterogeneous reactions representing the oxidative processing of atmospheric organic aerosols. A critical source of uncertainty in reactivity estimates is a lack of understanding of the mechanism through which some VOCs are oxidized. This knowledge gap is especially critical for aromatic compounds. Because the intermediate reaction steps and products of aromatics oxidation are unknown, chemical mechanisms incorporate parameters estimated from environmental chamber experiments to represent their overall contribution to ozone formation, e.g. Volkamer et al. ( 2006). Previous studies of uncertainties in incremental reactivity estimates for VOCs found that the representation of aromatics chemistry contributed significantly to the estimated 40 - 50% uncertainties in the incremental reactivities of common aromatic compounds Carter et al. (2002). This study shows development of an effective IR method that can monitor the reaction and hence obtain the kinetics of the ozonolysis of an aromatic compound in the aerosol phase. The development of such

  7. Closing the global atmospheric N2O budget: nitrous oxide emissions through the agricultural nitrogen cycle; OECD/IPCC/IEA Phase II Development of IPCC Guidelines for National Greenhouse Gas Inventories.

    NARCIS (Netherlands)

    Mosier, A.; Kroeze, C.; Nevison, C.; Oenema, O.; Seitzinger, S.; Cleempu., van O.

    1998-01-01

    In 1995 a working group was assembled at the request of OECD/IPCC/IEA to revise the methodology for N2O from agriculture for the National Greenhouse Gas Inventories Methodology. The basics of the methodology developed to calculate annual country level nitrous oxide (N2O) emissions from agricultural

  8. Synthesis of double oxides TiO2-SiO2 with low titanium content by hydrolysis of tetrabutoxytitanium-tetraethoxysilane mixture in an atmosphere of water vapor and ammonia

    OpenAIRE

    Shishmakov, A. B.; Koryakova, O. V.; Seleznev, A. S.; Petrov, L. A.; Melkozerov, S. A.

    2013-01-01

    A series of TiO2-SiO2 binary xerogels with the titanium content lower than 7 mol % were prepared by joint hydrolysis of tetrabutoxytitanium and tetraethoxysilane in a desiccator in the atmosphere of vapor over 5% aqueous NH3 solution under static conditions. The physicochemical properties of the material were examined by IR spectroscopy and by the kinetic method with hydrogen peroxide decomposition as model reaction. © 2013 Pleiades Publishing, Ltd.

  9. 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

  10. Evolution of Earth-like Extrasolar Planetary Atmospheres: Assessing the Atmospheres and Biospheres of Early Earth Analog Planets with a Coupled Atmosphere Biogeochemical Model

    Science.gov (United States)

    Gebauer, S.; Grenfell, J. L.; Stock, J. W.; Lehmann, R.; Godolt, M.; von Paris, P.; Rauer, H.

    2017-01-01

    Understanding the evolution of Earth and potentially habitable Earth-like worlds is essential to fathom our origin in the Universe. The search for Earth-like planets in the habitable zone and investigation of their atmospheres with climate and photochemical models is a central focus in exoplanetary science. Taking the evolution of Earth as a reference for Earth-like planets, a central scientific goal is to understand what the interactions were between atmosphere, geology, and biology on early Earth. The Great Oxidation Event in Earth's history was certainly caused by their interplay, but the origin and controlling processes of this occurrence are not well understood, the study of which will require interdisciplinary, coupled models. In this work, we present results from our newly developed Coupled Atmosphere Biogeochemistry model in which atmospheric O2 concentrations are fixed to values inferred by geological evidence. Applying a unique tool (Pathway Analysis Program), ours is the first quantitative analysis of catalytic cycles that governed O2 in early Earth's atmosphere near the Great Oxidation Event. Complicated oxidation pathways play a key role in destroying O2, whereas in the upper atmosphere, most O2 is formed abiotically via CO2 photolysis. The O2 bistability found by Goldblatt et al. (2006) is not observed in our calculations likely due to our detailed CH4 oxidation scheme. We calculate increased CH4 with increasing O2 during the Great Oxidation Event. For a given atmospheric surface flux, different atmospheric states are possible; however, the net primary productivity of the biosphere that produces O2 is unique. Mixing, CH4 fluxes, ocean solubility, and mantle/crust properties strongly affect net primary productivity and surface O2 fluxes. Regarding exoplanets, different "states" of O2 could exist for similar biomass output. Strong geological activity could lead to false negatives for life (since our analysis suggests that reducing gases remove O2 that

  11. 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

  12. 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. Copyright © 2014 Elsevier Ltd. All rights reserved.

  13. 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.

  14. Atmospheric Circulation of Exoplanets

    OpenAIRE

    Showman, Adam P.; Cho, James Y-K.; 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-wate...

  15. Designing Dynamic Atmospheres

    DEFF Research Database (Denmark)

    Kinch, Sofie; Højlund, Marie

    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,....... The potentials and implica-­‐ tions are presented through a design case, Kidkit, highlighting temporality as design parametre within interaction design.......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...

  16. Atmospheric Measurements Laboratory (AML)

    Data.gov (United States)

    Federal Laboratory Consortium — The Atmospheric Measurements Laboratory (AML) is one of the nation's leading research facilities for understanding aerosols, clouds, and their interactions. The AML...

  17. Effect of drinking water disinfection by-products in human peripheral blood lymphocytes and sperm.

    Science.gov (United States)

    Ali, Aftab; Kurzawa-Zegota, Malgorzata; Najafzadeh, Mojgan; Gopalan, Rajendran C; Plewa, Michael J; Anderson, Diana

    2014-12-01

    Drinking water disinfection by-products (DBPs) are generated by the chemical disinfection of water and may pose hazards to public health. Two major classes of DBPs are found in finished drinking water: haloacetic acids (HAAs) and trihalomethanes (THMs). HAAs are formed following disinfection with chlorine, which reacts with iodide and bromide in the water. Previously the HAAs were shown to be cytotoxic, genotoxic, mutagenic, teratogenic and carcinogenic. To determine the effect of HAAs in human somatic and germ cells and whether oxidative stress is involved in genotoxic action. In the present study both somatic and germ cells have been examined as peripheral blood lymphocytes and sperm. The effects of three HAA compounds: iodoacetic acid (IAA), bromoacetic acid (BAA) and chloroacetic acid (CAA) were investigated. After determining appropriate concentration responses, oxygen radical involvement with the antioxidants, butylated hydroxanisole (BHA) and the enzyme catalase, were investigated in the single cell gel electrophoresis (Comet) assay under alkaline conditions, >pH 13 and the micronucleus assay. In the Comet assay, BHA and catalase were able to reduce DNA damage in each cell type compared to HAA alone. In the micronucleus assay, micronuclei (MNi) were found in peripheral lymphocytes exposed to all three HAAs and catalase and BHA were in general, able to reduce MNi induction, suggesting oxygen radicals play a role in both assays. These observations are of concern to public health since both human somatic and germ cells show similar genotoxic responses. Copyright © 2014. Published by Elsevier B.V.

  18. Occurrence and control of nitrogenous disinfection by-products in drinking water--a review.

    Science.gov (United States)

    Bond, Tom; Huang, Jin; Templeton, Michael R; Graham, Nigel

    2011-10-01

    The presence of nitrogenous disinfection by-products (N-DBPs), including nitrosamines, cyanogen halides, haloacetonitriles, haloacetamides and halonitromethanes, in drinking water is of concern due to their high genotoxicity and cytotoxicity compared with regulated DBPs. Occurrence of N-DBPs is likely to increase if water sources become impacted by wastewater and algae. Moreover, a shift from chlorination to chloramination, an option for water providers wanting to reduce regulated DBPs such as trihalomethanes (THMs) and haloacetic acids (HAAs), can also increase certain N-DBPs. This paper provides a critical review of the occurrence and control of N-DBPs. Data collated from surveys undertaken in the United States and Scotland were used to calculate that the sum of analysed halonitromethanes represented 3-4% of the mass of THMs on a median basis; with Pearson product moment correlation coefficients of 0.78 and 0.83 between formation of dihaloacetonitriles and that of THMs and HAAs respectively. The impact of water treatment processes on N-DBP formation is complex and variable. While coagulation and filtration are of moderate efficacy for the removal of N-DBP precursors, such as amino acids and amines, biofiltration, if used prior to disinfection, is particularly successful at removing cyanogen halide precursors. Oxidation before final disinfection can increase halonitromethane formation and decrease N-nitrosodimethylamine, and chloramination is likely to increase cyanogen halides and NDMA relative to chlorination. Copyright © 2011 Elsevier Ltd. All rights reserved.

  19. Volatile disinfection by-product analysis from chlorinated indoor swimming pools.

    Science.gov (United States)

    Weaver, William A; Li, Jing; Wen, Yuli; Johnston, Jessica; Blatchley, Michael R; Blatchley, Ernest R

    2009-07-01

    Chlorination of indoor swimming pools is practiced for disinfection and oxidation of reduced compounds that are introduced to water by swimmers. However, there is growing concern associated with formation for chlorinated disinfection by-products (DBPs) in these settings. Volatile DBPs are of particular concern because they may promote respiratory ailments and other adverse health effects among swimmers and patrons of indoor pool facilities. To examine the scope of this issue, water samples were collected from 11 pools over a 6month period and analyzed for free chlorine and their volatile DBP content. Eleven volatile DBPs were identified: monochloramine (NH(2)Cl), dichloramine (NHCl(2)), trichloramine (NCl(3)), chloroform (CHCl(3)), bromoform (CHBr(3)), dichlorobromomethane (CHBrCl(2)), dibromochloromethane (CHBr(2)Cl), cyanogen chloride (CNCl), cyanogen bromide (CNBr), dichloroacetonitrile (CNCHCl(2)), and dichloromethylamine (CH(3)NCl(2)). Of these 11 DBPs, 10 were identified as regularly occurring, with CHBrCl(2) only appearing sporadically. Pool water samples were analyzed for residual chlorine compounds using the DPD colorimetric method and by membrane introduction mass spectrometry (MIMS). These two methods were chosen as complementary measures of residual chlorine, and to allow for comparisons between the methods. The DPD method was demonstrated to consistently overestimate inorganic chloramine content in swimming pools. Pairwise correlations among the measured volatile DBPs allowed identification of dichloromethylamine and dichloroacetonitrile as potential swimming pool water quality indicator compounds.

  20. Multiple linear regression modeling of disinfection by-products formation in Istanbul drinking water reservoirs.

    Science.gov (United States)

    Uyak, Vedat; Ozdemir, Kadir; Toroz, Ismail

    2007-06-01

    Oxidation of raw water with chlorine results in formation of trihalomethanes (THM) and haloacetic acids (HAA). Factors affecting their concentrations have been found to be organic matter type and concentration, pH, temperature, chlorine dose, contact time and bromide concentration, but the mechanisms of their formation are still under investigation. Within this scope, chlorination experiments have been conducted with water reservoirs from Terkos, Buyukcekmece and Omerli lakes, Istanbul, with different water quality regarding bromide concentration and organic matter content. The factors studied were pH, contact time, chlorine dose, and specific ultraviolet absorbance (SUVA). The determination of disinfection by-products (DBP) was carried out by gas chromatography techniques. Statistical analysis of the results was focused on the development of multiple regression models for predicting the concentrations of total THM and total HAA based on the use of pH, contact time, chlorine dose, and SUVA. The developed models provided satisfactory estimations of the concentrations of the DBP and the model regression coefficients of THM and HAA are 0.88 and 0.61, respectively. Further, the Durbin-Watson values confirm the reliability of the two models. The results indicate that under these experimental conditions which indicate the variations of pH, chlorine dosages, contact time, and SUVA values, the formation of THM and HAA in water can be described by the multiple linear regression technique.

  1. Storage stability of traditional Tunisian butter enriched with antioxidant extract from tomato processing by-products.

    Science.gov (United States)

    Abid, Yousra; Azabou, Samia; Jridi, Mourad; Khemakhem, Ibtihel; Bouaziz, Mohamed; Attia, Hamadi

    2017-10-15

    Traditional Tunisian butter (TTB) is one of the most appreciated dairy products in Tunisia. Herein, the storage stability of TTB enriched with antioxidants from tomato processing by-products (TPB) was evaluated during 60days of storage at 4°C. TPB extract contains significant amounts of lycopene and phenolics. TTB enriched with 400mg of TPB extract/kg of TTB revealed the lowest peroxide values at all the determination intervals. Adding 400mg of TPB extract/kg of TTB did not exhibit any undesired effect on lactic bacteria which are necessary for development of aroma and chemical properties of TTB. However, raw TTB and highly enriched TTB (800mg of TPB extract/kg of TTB) displayed higher lipid peroxidation. The detrimental effect of high antioxidant amounts on TTB stability could be due to a possible pro-oxidant character. Thus, appropriate supplementation of TPB extract could be used in TTB as a protective agent against lipid peroxidation to extend its shelf-life up to two months. Copyright © 2017 Elsevier Ltd. All rights reserved.

  2. Photochemistry of planetary atmospheres. [Mars atmospheric composition

    Science.gov (United States)

    Stief, L. J.

    1973-01-01

    The atmospheric composition of Mars is presented, and the applicability of laboratory data on CO2 absorption cross sections and quantum yields of dissociation is discussed. A summary and critical evaluation are presented on the various mechanisms proposed for converting the photodissociation products CO and O2 back to CO2.

  3. A Statistical Review of Alternative Zinc and Copper Extraction from Mineral Fertilizers and Industrial By-Products.

    Science.gov (United States)

    Cenciani de Souza, Camila Prado; Aparecida de Abreu, Cleide; Coscione, Aline Renée; Alberto de Andrade, Cristiano; Teixeira, Luiz Antonio Junqueira; Consolini, Flavia

    2018-01-01

    Rapid, accurate, and low-cost alternative analytical methods for micronutrient quantification in fertilizers are fundamental in QC. The purpose of this study was to evaluate whether zinc (Zn) and copper (Cu) content in mineral fertilizers and industrial by-products determined by the alternative methods USEPA 3051a, 10% HCl, and 10% H2SO4 are statistically equivalent to the standard method, consisting of hot-plate digestion using concentrated HCl. The commercially marketed Zn and Cu sources in Brazil consisted of oxides, carbonate, and sulfate fertilizers and by-products consisting of galvanizing ash, galvanizing sludge, brass ash, and brass or scrap slag. The contents of sources ranged from 15 to 82% and 10 to 45%, respectively, for Zn and Cu. The Zn and Cu contents refer to the variation of the elements found in the different sources evaluated with the concentrated HCl method as shown in Table 1. A protocol based on the following criteria was used for the statistical analysis assessment of the methods: F-test modified by Graybill, t-test for the mean error, and linear correlation coefficient analysis. In terms of equivalents, 10% HCl extraction was equivalent to the standard method for Zn, and the results of the USEPA 3051a and 10% HCl methods indicated that these methods were equivalents for Cu. Therefore, these methods can be considered viable alternatives to the standard method of determination for Cu and Zn in mineral fertilizers and industrial by-products in future research for their complete validation.

  4. Controlled Atmosphere Stunning

    NARCIS (Netherlands)

    Lambooij, E.; Gerritzen, M.A.

    2009-01-01

    Controlled atmosphere (CAS) stunning includes several variations of gaseous mixtures given to induce an anaesthetic state before slaughter poultry. One method of multi phase CAS is to unload the birds out of the crate on a conveyor belt and subject the birds to an atmosphere of 30% O2, 40% CO2 and

  5. 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...

  6. The Power of Atmosphere

    DEFF Research Database (Denmark)

    Wieczorek, Izabela

    2014-01-01

    composed of bubbles of affects – that is, the particles that are charged with power and normativity. References Grtiffero, T. (2014 (2010)). Atmospheres: Aesthetics of Emotional Spaces. Ashgate Philippopoulos-Mihalopoulos, A. (2013). Atmospheres of law: Senses, affects, lawscapes, in Emotion, Space...

  7. 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....... The potentials and implications are presented through a design case, Kidkit, highlighting temporality as design parametre within interaction design....

  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. Consumption of atmospheric methane by tundra soils

    OpenAIRE

    Whalen, SC; Reeburgh, WS

    1990-01-01

    EMISSION of methane from tundra soil contributes about 10% of the global atmospheric methane budget 1 . Moreover, tundra soils contain 15% of global soil carbon 2 , so the response of this large carbon reservoir to projected global warming 3,4 could be important. Coupled biological models 3-6 predict that a warmer climate will increase methane emission through increased rates of methanogenesis. Microbial oxidation of methane is, however, a possible control on emissions that has previously b...

  10. Atmosphere Impact Losses

    Science.gov (United States)

    Schlichting, Hilke E.; Mukhopadhyay, Sujoy

    2018-02-01

    Determining the origin of volatiles on terrestrial planets and quantifying atmospheric loss during planet formation is crucial for understanding the history and evolution of planetary atmospheres. Using geochemical observations of noble gases and major volatiles we determine what the present day inventory of volatiles tells us about the sources, the accretion process and the early differentiation of the Earth. We further quantify the key volatile loss mechanisms and the atmospheric loss history during Earth's formation. Volatiles were accreted throughout the Earth's formation, but Earth's early accretion history was volatile poor. Although nebular Ne and possible H in the deep mantle might be a fingerprint of this early accretion, most of the mantle does not remember this signature implying that volatile loss occurred during accretion. Present day geochemistry of volatiles shows no evidence of hydrodynamic escape as the isotopic compositions of most volatiles are chondritic. This suggests that atmospheric loss generated by impacts played a major role during Earth's formation. While many of the volatiles have chondritic isotopic ratios, their relative abundances are certainly not chondritic again suggesting volatile loss tied to impacts. Geochemical evidence of atmospheric loss comes from the {}3He/{}^{22}Ne, halogen ratios (e.g., F/Cl) and low H/N ratios. In addition, the geochemical ratios indicate that most of the water could have been delivered prior to the Moon forming impact and that the Moon forming impact did not drive off the ocean. Given the importance of impacts in determining the volatile budget of the Earth we examine the contributions to atmospheric loss from both small and large impacts. We find that atmospheric mass loss due to impacts can be characterized into three different regimes: 1) Giant Impacts, that create a strong shock transversing the whole planet and that can lead to atmospheric loss globally. 2) Large enough impactors (m_{cap} ≳ √{2

  11. Measurements of Oxygenated Organic Chemicals In the Pacific Troposphere During TRACE-P: Higher Aldehydes (less than C(sub 1)), Their Sources, and Potential Role In Atmospheric Oxidation

    Science.gov (United States)

    Singh, Hanwant B.; Salas, L.; Herlth, D.; Viezee, W.; Fried, A.; Jackob, D.; Blake, D.; Heikes, B.; Talbot, R.; Sachse, G.; hide

    2002-01-01

    Airborne measurements of a large number of oxygenated organics were carried out in the Pacific troposphere (to 12 km) in the Spring of 2001 (Feb. 24-April 10). Specifically these measurements included acetaldehyde, propanaldehyde, acetone, methylethyl ketone, methanol, ethanol, PAM and organic nitrates. Independent measurements of formaldehyde, peroxides, and tracers were also available. Highly polluted as well as pristine air masses were sampled. Oxygenated organics were abundant in the clean In troposphere and were greatly enhanced in the outflow regions from Asia. Extremely high concentrations of aldehydes could be measured in the troposphere. It is not possible to explain the large abundances of aldehydes in the background troposphere without invoking significant oceanic sources. A strong correlation between the observed mixing ratios of formaldehyde and acetaldehyde is present. We infer that higher aldehydes (such as acetaldehyde and propanaldehyde) may provide a large source of formaldehyde and sequester Cox throughout the troposphere. The atmospheric behavior of acetone, methylethyl ketone, and methanol is generally indicative of their common terrestrial sources with a Image contribution from biomass/biofuel burning. A vast body of data has been collected and it is being analyzed both statistically and with the help of models to better understand the role that oxygenated organics play in the atmosphere and to unravel their sources and sinks. These results will be presented.

  12. Mineralogical features of size and density fractions in Sasol coal gasification ash, South Africa and potential by-products

    Energy Technology Data Exchange (ETDEWEB)

    R.H. Matjie; C. Van Alphen [Sasol Technology (Pty) Ltd., Sasolburg (South Africa)

    2008-07-15

    Bulk gasification ash (a mixture of coarse and fine ash particles), a by-product of coal gasification, is formed at elevated temperatures and pressures by the interaction of included minerals present in the coal and 'stone'. From the detailed mineralogical and chemical analyses of the pulverised screened size fractions and one density float fraction ({lt}1.9 g/cm{sup 3}) a number of potential viable by-products were identified. Screening and density separation produced a high ash, low volatile carbon-rich by-product, which is potentially suitable as an energy source for the cement industry. In addition, this carbon-rich product has included devolatilised kaolinite and quartz that are a source of Al{sub 2}O{sub 3} and SiO{sub 2}. This product could potentially replace the amount of clay required in the cement process. This high ash carbon product is not suitable as a reductant in the metallurgical industry. The -38 + 20 {mu}m ash size fraction is characterised by a comparatively high proportion of aluminosilicate (transformed product of kaolinite) and Ca-oxide/CaMg-oxide (transformed product of calcite/dolomite). These phases will enhance the pozzolanic reactivity of this ash size fraction and provide material suitable for the cement/concrete industry. The coarse ash size fractions are used as aggregate in road construction and in the manufacture of bricks. If economically and technically feasible, anorthite in the coarse ash size fractions could be beneficiated and used in a refractory. 12 refs., 9 figs., 2 tabs.

  13. Atmospheric Capture On Mars (and Processing)

    Science.gov (United States)

    Muscatello, Tony

    2017-01-01

    The ultimate destination of NASA's human exploration program is Mars. In Situ Resource Utilization (ISRU) is a key technology required to enable such missions, as first proposed by Prof. Robert Ash in 1976. This presentation will review progress in the systems required to produce rocket propellant, oxygen, and other consumables on Mars using the carbon dioxide atmosphere and other potential resources. For many years, NASA, commercial companies, and academia have been developing, and demonstrating techniques to capture and purify Martian atmospheric gases for their utilization for the production of hydrocarbons, oxygen, and water in ISRU systems. Other gases will be required to be separated from Martian atmospheric gases to provide pure CO2 for processing elements. Significant progress has been demonstrated in CO2 collection via adsorption by molecular sieves, freezing, and direct compression. Early stage work in adsorption in Ionic Liquids followed by electrolysis to oxygen is also underway. In addition, other Martian gases, such as nitrogen and argon, occur in concentrations high enough to be useful as buffer gas and could be captured as well. Gas separation requirements include, but are not limited to the selective separation of: (1) methane and water from unreacted carbon oxides (CO2-CO) and hydrogen typical of a Sabatier-type process, (2) carbon oxides and water from unreacted hydrogen from a Reverse Water-Gas Shift process, and (3) carbon oxides from oxygen from a trash/waste processing reaction.

  14. Atmospheric composition change: Ecosystems–Atmosphere interactions

    DEFF Research Database (Denmark)

    Fowler, D.; Pilegaard, Kim; Sutton, M.A.

    2009-01-01

    in the size range 1 nm–10 μm including organic and inorganic chemical species. The main focus of the review is on the exchange between terrestrial ecosystems, both managed and natural and the atmosphere, although some new developments in ocean–atmosphere exchange are included. The material presented is biased...... and techniques in micrometeorology. For some of the compounds there have been paradigm shifts in approach and application of both techniques and assessment. These include flux measurements over marine surfaces and urban areas using micrometeorological methods and the up-scaling of flux measurements using...... aircraft and satellite remote sensing. The application of a flux-based approach in assessment of O3 effects on vegetation at regional scales is an important policy linked development secured through improved quantification of fluxes. The coupling of monitoring, modelling and intensive flux measurement...

  15. 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

  16. Dynamics of Massive Atmospheres

    Science.gov (United States)

    Chemke, Rei; Kaspi, Yohai

    2017-10-01

    The many recently discovered terrestrial exoplanets are expected to hold a wide range of atmospheric masses. Here the dynamic-thermodynamic effects of atmospheric mass on atmospheric circulation are studied using an idealized global circulation model by systematically varying the atmospheric surface pressure. On an Earth analog planet, an increase in atmospheric mass weakens the Hadley circulation and decreases its latitudinal extent. These changes are found to be related to the reduction of the convective fluxes and net radiative cooling (due to the higher atmospheric heat capacity), which, respectively, cool the upper troposphere at mid-low latitudes and warm the troposphere at high latitudes. These together decrease the meridional temperature gradient, tropopause height and static stability. The reduction of these parameters, which play a key role in affecting the flow properties of the tropical circulation, weakens and contracts the Hadley circulation. The reduction of the meridional temperature gradient also decreases the extraction of mean potential energy to the eddy fields and the mean kinetic energy, which weakens the extratropical circulation. The decrease of the eddy kinetic energy decreases the Rhines wavelength, which is found to follow the meridional jet scale. The contraction of the jet scale in the extratropics results in multiple jets and meridional circulation cells as the atmospheric mass increases.

  17. Atmospheric refraction: a history

    Science.gov (United States)

    Lehn, Waldemar H.; van der Werf, Siebren

    2005-09-01

    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 uniform density up to a sharp upper transition to the ether, at which the refraction occurred. Alhazen and Witelo transmitted his knowledge to medieval Europe. The first accurate measurements were made by Tycho Brahe in the 16th century. Finally, Kepler, who was aware of unusually strong refractions, used the Ptolemaic model to explain the first documented and recognized mirage (the Novaya Zemlya effect).

  18. New atmospheric program

    Science.gov (United States)

    The National Science Foundation's Division of Atmospheric Sciences has established an Upper Atmospheric Facilities program within its Centers and Facilities section. The program will support the operation of and the scientific research that uses the longitudinal chain of incoherent scatter radars. The program also will ensure that the chain is maintained as a state-of-the-art research tool available to all interested and qualified scientists.For additional information, contact Richard A. Behnke, Division of Atmospheric Sciences, National Science Foundation, 1800 G Street, N.W., Washington, DC 20550 (telephone: 202-357-7390).

  19. Discovery of atmospheric neutrino oscillations

    Energy Technology Data Exchange (ETDEWEB)

    Kajita, Takaaki [Tokyo Univ., Inst. for Cosmic Ray Research, Kashiwa, Chiba (Japan)

    2003-05-01

    Cosmic ray particles entering the atmosphere interact with the air nuclei produce neutrinos. These neutrinos are called atmospheric neutrinos. The atmospheric neutrino anomaly observed in Kamiokande is now understood as due to neutrino oscillations by high statistics measurements of the atmospheric neutrinos in Super-Kamiokande. The studies of the atmospheric neutrinos have matured into detailed studies of neutrino masses and mixings. (author)

  20. Comparison of thermal oxidation and plasma oxidation of 4H-SiC (0001) for surface flattening

    Science.gov (United States)

    Deng, Hui; Endo, Katsuyoshi; Yamamura, Kazuya

    2014-03-01

    The thermal oxidation and water vapor plasma oxidation of 4H-SiC (0001) were investigated. The initial oxidation rate of helium-based atmospheric-pressure plasma oxidation was six times higher than that of thermal oxidation. The oxide-SiC interface generated by plasma oxidation became flatter with increasing thickness of the oxide, whereas the interface generated by thermal oxidation was atomically flat regardless of the oxide thickness. Many pits were generated on the thermally oxidized surface, whereas few pits were observed on the surface oxidized by plasma. After the oxide layer generated plasma oxidation was removed, an atomically flat and pit-free SiC surface was obtained.

  1. Photosynthesis in Hydrogen-Dominated Atmospheres

    Directory of Open Access Journals (Sweden)

    William Bains

    2014-11-01

    Full Text Available The diversity of extrasolar planets discovered in the last decade shows that we should not be constrained to look for life in environments similar to early or present-day Earth. Super-Earth exoplanets are being discovered with increasing frequency, and some will be able to retain a stable, hydrogen-dominated atmosphere. We explore the possibilities for photosynthesis on a rocky planet with a thin H2-dominated atmosphere. If a rocky, H2-dominated planet harbors life, then that life is likely to convert atmospheric carbon into methane. Outgassing may also build an atmosphere in which methane is the principal carbon species. We describe the possible chemical routes for photosynthesis starting from methane and show that less energy and lower energy photons could drive CH4-based photosynthesis as compared with CO2-based photosynthesis. We find that a by-product biosignature gas is likely to be H2, which is not distinct from the hydrogen already present in the environment. Ammonia is a potential biosignature gas of hydrogenic photosynthesis that is unlikely to be generated abiologically. We suggest that the evolution of methane-based photosynthesis is at least as likely as the evolution of anoxygenic photosynthesis on Earth and may support the evolution of complex life.

  2. Photosynthesis in Hydrogen-Dominated Atmospheres

    Science.gov (United States)

    Bains, William; Seager, Sara; Zsom, Andras

    2014-01-01

    The diversity of extrasolar planets discovered in the last decade shows that we should not be constrained to look for life in environments similar to early or present-day Earth. Super-Earth exoplanets are being discovered with increasing frequency, and some will be able to retain a stable, hydrogen-dominated atmosphere. We explore the possibilities for photosynthesis on a rocky planet with a thin H2-dominated atmosphere. If a rocky, H2-dominated planet harbors life, then that life is likely to convert atmospheric carbon into methane. Outgassing may also build an atmosphere in which methane is the principal carbon species. We describe the possible chemical routes for photosynthesis starting from methane and show that less energy and lower energy photons could drive CH4-based photosynthesis as compared with CO2-based photosynthesis. We find that a by-product biosignature gas is likely to be H2, which is not distinct from the hydrogen already present in the environment. Ammonia is a potential biosignature gas of hydrogenic photosynthesis that is unlikely to be generated abiologically. We suggest that the evolution of methane-based photosynthesis is at least as likely as the evolution of anoxygenic photosynthesis on Earth and may support the evolution of complex life. PMID:25411926

  3. Atmospheric Transport Modeling Resources

    Energy Technology Data Exchange (ETDEWEB)

    Mazzola, Carl A. [Stone and Webster Engineering Corporation, Aiken, SC (United States); Addis, Robert P. [Westinghouse Savannah River Company, Aiken, SC (United States)

    1995-03-01

    The purpose of this publication is to provide DOE and other federal agency emergency managers with an in-depth compilation and description of atmospheric dispersion models available to DOE and other Federal sites.

  4. Atmospheric Heavy Metal Pollution

    Indian Academy of Sciences (India)

    Home; Journals; Resonance – Journal of Science Education; Volume 6; Issue 4. Atmospheric Heavy Metal Pollution - Development of Chronological Records and Geochemical Monitoring. Rohit Shrivastav. General Article Volume 6 Issue 4 April 2001 pp 62-68 ...

  5. Students 'Weigh' Atmospheric Pollution.

    Science.gov (United States)

    Caporaloni, Marina

    1998-01-01

    Describes a procedure developed by students that measures the mass concentration of particles in a polluted urban atmosphere. Uses a portable fan and filters of various materials. Compares students' data with official data. (DDR)

  6. Our Changing Atmosphere.

    Science.gov (United States)

    Clearing, 1988

    1988-01-01

    Summarizes what is known about two major variables involved in certain types of chemical pollution that seem to be changing the structure of the Earth's atmosphere. Discusses the greenhouse effect and the ozone layer. (TW)

  7. Global atmospheric changes.

    OpenAIRE

    Piver, W T

    1991-01-01

    Increasing concentrations of CO2 and other greenhouse gases in the atmosphere can be directly related to global warming. In terms of human health, because a major cause of increasing atmospheric concentrations of CO2 is the increased combustion of fossil fuels, global warming also may result in increases in air pollutants, acid deposition, and exposure to ultraviolet (UV) radiation. To understand better the impacts of global warming phenomena on human health, this review emphasizes the proces...

  8. AFCI Transmutation Fuel Processes and By-Products Planning: Interim Report

    Energy Technology Data Exchange (ETDEWEB)

    Eric L. Shaber

    2005-09-01

    dictates the need for detailed process flows, mass balances, batch size data, and radiological dose estimates. Full definition of the materials that will need to be handled in the facility as feed material inputs, in-process fuel, scrap recycle, scrap requiring recovery, and by-product wastes is required. The feed material for demonstrating transmutation fuel fabrication will need to come from the separations of actinides from spent nuclear fuel processed in the same AFCF.

  9. Antioxidant capacity of hydrolyzed animal by-products and relation to amino acid composition and peptide size distribution.

    Science.gov (United States)

    Damgaard, Trine; Lametsch, René; Otte, Jeanette

    2015-10-01

    The antioxidative capacity of six different tissue hydrolysates (porcine colon, heart and neck and bovine lung, kidney and pancreas) were tested by three different assays monitoring iron chelation, ABTS radical scavenging and inhibition of lipid oxidation in emulsions, respectively. The hydrolysates were also investigated with respect to amino acid composition and peptide size distribution. The hydrolysates contained peptides ranging from 20 kDa to below 100 Da with a predominance of peptides with low molecular weight (53.8 to 89.0 % below 3 kDa). All hydrolysates exhibited antioxidant activity as assessed with all three methods; inhibition of lipid oxidation ranging from 72 to 88 % (at a final protein concentration of 7 mg/mL), iron chelation capacity from 23 to 63 % (at 1.1 mg/mL), and ABTS radical scavenging from 38 to 50 % (at 10 μg /mL). The antioxidant activity did not correlate with the proportion of low molecular weight peptides in the hydrolysed tissues, but with the content of specific amino acid residues. The ABTS radical scavenging capacity of the tissues was found to correlate with the content of Trp, Tyr, Met and Arg, whereas the ability to inhibit the oxidation of lineoleic acid correlated with the content of Glu and His. The chosen animal by-products thus represent a natural source of antioxidants with potential for food application.

  10. 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. Copyright © 2014 Elsevier Ltd. All rights reserved.

  11. Dynamics in Atmospheric Physics

    Science.gov (United States)

    Lindzen, Richard A.

    2005-08-01

    Motion is manifest in the atmosphere in an almost infinite variety of ways. In Dynamics in Atmospheric Physics, Dr. Richard Lindzen describes the nature of motion in the atmosphere, develops fluid dynamics relevant to the atmosphere, and explores the role of motion in determining the climate and atmospheric composition. The author presents the material in a lecture note style, and the emphasis throughout is on describing phenomena that are at the frontiers of current research, but due attention is given to the methodology of research and to the historical background of these topics. The author's treatment and choice of topics is didactic. Problems at the end of each chapter will help students assimilate the material. In general the discussions emphasize physical concepts, and throughout Dr. Lindzen makes a concerted effort to avoid the notion that dynamic meteorology is simply the derivation of equations and their subsequent solution. His desire is that interested students will delve further into solution details. The book is intended as a text for first year graduate students in the atmospheric sciences. Although the material in the book is self contained, a familiarity with differential equations is assumed; some background in fluid mechanics is helpful.

  12. 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.

  13. Catalytic oxidation using nitrous oxide

    Directory of Open Access Journals (Sweden)

    Juan Carlos Beltran-Prieto

    2017-01-01

    Full Text Available Nitrous oxide is a very inert gas used generally as oxidant as it offers some advantage compared with other oxidants such as O2 but a considerably higher temperature (> 526 °C is often required. For particular cases such as the oxidation of sugar alcohols, especially for the oxidation of primary alcohols to aldehydes, N2O has the advantage over O2 of a higher reaction selectivity. In the present paper we present the modelling of oxidation reaction of sugar alcohols using an oxidizing agent in low concentrations, which is important to suppress subsequent oxidation reactions due to the very low residual concentrations of the oxidizing agent. For orientation experiments we chose nitrous oxide generated by thermal decomposition of ammonium nitrate. Kinetic modeling of the reaction was performed after determination of the differential equations that describe the system under study.

  14. Atmospheric Circulation of Exoplanets

    Science.gov (United States)

    Showman, A. P.; Cho, J. Y.-K.; Menou, K.

    2010-12-01

    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 simple 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 dynamics are given particular attention, as these close-in planets have been the subject of most of the concrete developments in the study of exoplanetary atmospheres. We then turn to the basic elements of circulation on terrestrial planets as inferred from solar system studies, including Hadley cells, jet streams, processes that govern the large-scale horizontal temperature contrasts, and climate, and we discuss how these insights may apply to terrestrial exoplanets. Although exoplanets surely possess a greater diversity of circulation regimes than seen on the planets in our solar system, our guiding philosophy is that the multidecade study of solar system planets reviewed here provides a foundation upon which our understanding of more exotic exoplanetary meteorology must build.

  15. Atmospheric Change on Pluto

    Science.gov (United States)

    Person, Michael

    2013-10-01

    We propose to use SOFIA with HIPO and FLITECAM (FLIPO) to measure the parameters of Pluto's atmosphere (temperature, pressure, possible particulate haze) by observing a stellar occultation by Pluto on 15 November 2014. Due to its highly elliptical orbit and seasonally variable obliquity, Pluto's atmosphere is predicted to condense onto its surface within the next ~10 years and possibly within the next few years and thus frequent observations are critical. Detection of the occultation central flash will allow measurement of the structure of Pluto's lower atmosphere and atmospheric oblateness. We will use FLIPO to measure the refracted starlight contemporaneously at visible and infrared wavelengths; this approach is needed to differentiate between two competing explanations for the deficiency in the observed light refracted from Pluto's lower atmosphere (strong thermal gradients versus variable particulate extinction). Only an airborne platform such as SOFIA has the flexibility to place a large telescope in the center of the shadow path of this brief event while at the same time nearly eliminating the possibility of missing time-critical observations due to unfortunate weather systems. Occultation predictions will be updated throughout the period preceding the observations with the goal of achieving sufficient prediction accuracy at the event time to place SOFIA directly in the path of Pluto's central flash. This SOFIA observation will be combined with our ongoing ground-based observing program whose goal is to measure the temporal variability of Pluto's atmosphere in response to its changing seasonal obliquity (and resulting ice migration) and recession from the sun. For the NASA New Horizons mission to Pluto and the Kuiper Belt, this Pluto occultation event represents the last chance, prior to the spacecraft closest approach to the Pluto/Charon system (July 2015), to provide input to the mission for encounter planning, as well as context and supporting atmospheric

  16. Characterization of Hanwoo Bovine By-products by Means of Yield, Physicochemical and Nutritional Compositions

    Science.gov (United States)

    Moon, Sung Sil

    2014-01-01

    Though the edible bovine by-products are widely used for human consumption in most countries worldwide but the scientific information regarding the nutritional quality of these by-products is scarce. In the present study, the basic information regarding the yields, physicochemical and nutritional compositions of edible Hanwoo bovine by-products was studied. Our results showed that the yields, physicochemical and nutritional composition widely varied between the by-products examined. The highest pH values were found in rumen, reticulum, omasum and reproductive organ. Heart, liver, kidney and spleen had the lowest CIE L* values and highest CIE a* values. Liver had the highest vitamin A, B2 and niacin contents whereas the highest B1 and B5 contents were found in kidney. The highest Ca content was found in rumen, reticulum, omasum, head and leg while the highest Mn and Fe contents were found in rumen, omasum and spleen, respectively. Liver had the highest Cu content. Total essential amino acids (EAA)/amino acids (AA) ratios ranged between the by-products from 38.37% to 47.41%. Total polyunsaturated fatty acids (PUFA) levels ranged between the by-products from 2.26% to 26.47%, and most by-products showed favorable PUFA/SFA ratios. It is concluded that most of by-products examined are good sources of essential nutrients and these data will be of great importance for promotion of consumption and utilization of beef by-products in future. PMID:26761281

  17. Fundamentals of Atmospheric Radiation

    Science.gov (United States)

    Bohren, Craig F.; Clothiaux, Eugene E.

    2006-02-01

    This textbook fills a gap in the literature for teaching material suitable for students of atmospheric science and courses on atmospheric radiation. It covers the fundamentals of emission, absorption, and scattering of electromagnetic radiation from ultraviolet to infrared and beyond. Much of the book applies to planetary atmosphere. The authors are physicists and teach at the largest meteorology department of the US at Penn State. Craig T. Bohren has taught the atmospheric radiation course there for the past 20 years with no book. Eugene Clothiaux has taken over and added to the course notes. Problems given in the text come from students, colleagues, and correspondents. The design of the figures especially for this book is meant to ease comprehension. Discussions have a graded approach with a thorough treatment of subjects, such as single scattering by particles, at different levels of complexity. The discussion of the multiple scattering theory begins with piles of plates. This simple theory introduces concepts in more advanced theories, i.e. optical thickness, single-scattering albedo, asymmetry parameter. The more complicated theory, the two-stream theory, then takes the reader beyond the pile-of-plates theory. Ideal for advanced undergraduate and graduate students of atmospheric science.

  18. Atmospheric pollution in Lisbon urban atmosphere

    Science.gov (United States)

    Oliveira, C.

    2009-04-01

    Lisbon is the capital city of Portugal with about 565,000 residents in 2008 and a population density of 6,600 inhabitants per square kilometre. Like several other major metropolis, the town is surrounded by satellite cities, forming together a region known as "Lisbon Metropolitan Area" with about 3 million inhabitants, a quarter of the overall Portuguese population. Besides their local residents, it is estimated that more than one million citizens come into the Lisbon area every day from the outskirts, leading to elevated traffic densities and intense traffic jams, with important consequences on air pollution levels and obvious negative impacts on human health. Airborne particulate matter limit values are frequently exceeded, making urgent the existence of consistent programs to monitor and help taking measures to control them. Within the Portuguese project PAHLIS (Polycyclic Aromatic Hydrocarbons Contamination in Lisbon Urban Atmosphere) financed by the Portuguese Science Foundation ("Fundação para a Ciência e a Tecnologia"), an aerosol and vapour phase sampling program is being implemented in the city of Lisbon at two selected contrasting zones, namely a typically busy area with intense road traffic and frequent exceedences of the particulate matter standard for the maximum allowable concentration, and a residential quieter area, thus with a cleaner atmosphere characterised as an urban background site. An one month-long sampling campaign was performed during the summer of 2008, where particulate matter was collected in two fractions (coarse 2.5µmcommunication, the results of both organic and inorganic analyses of aerosol samples from these two sites will be presented, compared and discussed. Results of this work are expected to cover a lack of reliable information regarding sources of atmospheric pollutants in Portugal and present, for the first time, systematic data of PAHs levels in Lisbon. Acknowledgement: This work was performed under Project PAHLIS (PTDC

  19. Neutralization/prevention of acid rock drainage using mixtures of alkaline by-products and sulfidic mine wastes.

    Science.gov (United States)

    Alakangas, Lena; Andersson, Elin; Mueller, Seth

    2013-11-01

    Backfilling of open pit with sulfidic waste rock followed by inundation is a common method for reducing sulfide oxidation after mine closure. This approach can be complemented by mixing the waste rock with alkaline materials from pulp and steel mills to increase the system's neutralization potential. Leachates from 1 m3 tanks containing sulfide-rich (ca.30 wt %) waste rock formed under dry and water saturated conditions under laboratory conditions were characterized and compared to those formed from mixtures. The waste rock leachate produced an acidic leachate (pH9). The decrease of elemental concentration in the leachate was most pronounced for Pb and Zn, while Al and S were relatively high. Overall, the results obtained were promising and suggest that alkaline by-products could be useful additives for minimizing ARD formation.

  20. Aerosolization and Atmospheric Transformation of Engineered Nanoparticles

    Science.gov (United States)

    Tiwari, Andrea J.

    While research on the environmental impacts of engineered nanoparticles (ENPs) is growing, the potential for them to be chemically transformed in the atmosphere has been largely ignored. The overall objective of this work was to assess the atmospheric transformation of carbonaceous nanoparticles (CNPs). The research focuses on C60 fullerene because it is an important member of the carbonaceous nanoparticle (CNP) family and is used in a wide variety of applications. The first specific objective was to review the potential of atmospheric transformations to alter the environmental impacts of CNPs. We described atmospheric processes that were likely to physically or chemically alter aerosolized CNPs and demonstrated their relevance to CNP behavior and toxicity in the aqueous and terrestrial environment. In order to investigate the transformations of CNP aerosols under controlled conditions, we developed an aerosolization technique that produces nano-scale aerosols without using solvents, which can alter the surface chemistry of the aerosols. We demonstrated the technique with carbonaceous (C60) and metal oxide (TiO2, CeO2) nanoparticle powders. All resulting aerosols exhibited unimodal size distributions and mode particle diameters below 100 nm. We used the new aerosolization technique to investigate the reaction between aerosolized C60 and atmospherically realistic levels of ozone (O3) in terms of reaction products, reaction rate, and oxidative stress potential. We identified C60O, C60O2, and C60O3 as products of the C60-O3 reaction. We demonstrated that the oxidative stress potential of C 60 may be enhanced by exposure to O3. We found the pseudo-first order reaction rate to be 9 x 10-6 to 2 x 10 -5 s-1, which is several orders of magnitude lower than the rate for several PAH species under comparable conditions. This research has demonstrated that a thorough understanding of atmospheric chemistry of ENPs is critical for accurate prediction of their environmental

  1. Phenomenology of atmospheric neutrinos

    Directory of Open Access Journals (Sweden)

    Fedynitch Anatoli

    2016-01-01

    Full Text Available The detection of astrophysical neutrinos, certainly a break-through result, introduced new experimental challenges and fundamental questions about acceleration mechanisms of cosmic rays. On one hand IceCube succeeded in finding an unambiguous proof for the existence of a diffuse astrophysical neutrino flux, on the other hand the precise determination of its spectral index and normalization requires a better knowledge about the atmospheric background at hundreds of TeV and PeV energies. Atmospheric neutrinos in this energy range originate mostly from decays of heavy-flavor mesons, which production in the phase space relevant for prompt leptons is uncertain. Current accelerator-based experiments are limited by detector acceptance and not so much by the collision energy. This paper recaps phenomenological aspects of atmospheric leptons and calculation methods, linking recent progress in flux predictions with particle physics at colliders, in particular the Large Hadron Collider.

  2. Intensifying the Atmospheric

    DEFF Research Database (Denmark)

    Liebst, Lasse Suonperä

    2012-01-01

    The phenomenological concept of urban atmospheres is more often applied as an aesthetic description of the metropolitan space as such. This conceptualization is supported in this paper; however, I strive to give the concept a post-phenomenological axial turn. While phenomenology, due to its under...... sufficiently intense. All things considered, the paper should be read as a sociological contribution to theoretically reconstruct the concept of urban atmospheres in the light of spatial morphology.......The phenomenological concept of urban atmospheres is more often applied as an aesthetic description of the metropolitan space as such. This conceptualization is supported in this paper; however, I strive to give the concept a post-phenomenological axial turn. While phenomenology, due to its...

  3. Atmosphere and Ambient Space

    DEFF Research Database (Denmark)

    Schmidt, Ulrik

    Atmosphere and Ambient Space This paper explores the relation between atmosphere and ambient space. Atmosphere and ambient space share many salient properties. They are both ontologically indeterminate, constantly varying and formally diffuse and they are both experienced as a subtle, non......-signifying property of a given space. But from a certain point of view, the two concepts also designate quite dissimilar experiences of space. To be ’ambient’ means to surround. Accordingly, ambient space is that space, which surrounds something or somebody. (Gibson 1987: 65) Since space is essentially...... of a surrounding character, all space can thus be described as having a fundamentally ambient character. So what precisely is an ambient space, then? As I will argue in my presentation, ambient space is a sensory effect of spatiality when a space is experienced as being particularly surrounding: a ‘space effect...

  4. Evolution of Earth-like Extrasolar Planetary Atmospheres: Assessing the Atmospheres and Biospheres of Early Earth Analog Planets with a Coupled Atmosphere Biogeochemical Model.

    Science.gov (United States)

    Gebauer, S; Grenfell, J L; Stock, J W; Lehmann, R; Godolt, M; von Paris, P; Rauer, H

    2017-01-01

    Understanding the evolution of Earth and potentially habitable Earth-like worlds is essential to fathom our origin in the Universe. The search for Earth-like planets in the habitable zone and investigation of their atmospheres with climate and photochemical models is a central focus in exoplanetary science. Taking the evolution of Earth as a reference for Earth-like planets, a central scientific goal is to understand what the interactions were between atmosphere, geology, and biology on early Earth. The Great Oxidation Event in Earth's history was certainly caused by their interplay, but the origin and controlling processes of this occurrence are not well understood, the study of which will require interdisciplinary, coupled models. In this work, we present results from our newly developed Coupled Atmosphere Biogeochemistry model in which atmospheric O2 concentrations are fixed to values inferred by geological evidence. Applying a unique tool (Pathway Analysis Program), ours is the first quantitative analysis of catalytic cycles that governed O2 in early Earth's atmosphere near the Great Oxidation Event. Complicated oxidation pathways play a key role in destroying O2, whereas in the upper atmosphere, most O2 is formed abiotically via CO2 photolysis. The O2 bistability found by Goldblatt et al. ( 2006 ) is not observed in our calculations likely due to our detailed CH4 oxidation scheme. We calculate increased CH4 with increasing O2 during the Great Oxidation Event. For a given atmospheric surface flux, different atmospheric states are possible; however, the net primary productivity of the biosphere that produces O2 is unique. Mixing, CH4 fluxes, ocean solubility, and mantle/crust properties strongly affect net primary productivity and surface O2 fluxes. Regarding exoplanets, different "states" of O2 could exist for similar biomass output. Strong geological activity could lead to false negatives for life (since our analysis suggests that reducing gases remove O2 that

  5. Anti-Inflammatory Effect of By-Products from Haliotis discus hannai in RAW 264.7 Cells

    Directory of Open Access Journals (Sweden)

    Ho-Seok Rho

    2015-01-01

    Full Text Available Several reports promoted the potential of shellfish due to their ability to act as antioxidant, anti-inflammatory, and antimicrobial agents. Pacific abalone, Haliotis discus hannai viscera is, reported to possess bioactivities such as antioxidative stress and anti-inflammatory. In this study, anti-inflammatory potential of mucus-secreting glands from shell-shucking waste of H. discus hannai was evaluated using RAW 264.7 mouse macrophage cell model. Results indicated that presence of H. discus hannai mucosubstance by-products (AM significantly lowered the nitric oxide (NO production along the expressional suppression of inflammatory mediators such as cytokines TNF-α, IL-1β, and IL-6 and enzymes iNOS and COX-2. Also, AM was shown to increase expression of anti-inflammatory response mediator HO-1. Presence of AM also scavenged the free radicals in vitro. In conclusion, by-products of H. discus hannai are suggested to possess notable anti-inflammatory potential which promotes the possibility of utilization as functional food ingredient.

  6. Effect of the addition of chia's by-product on the composition of fatty acids in hamburgers through chemometric methods.

    Science.gov (United States)

    Souza, Aloisio H P; Gohara, Aline K; Rotta, Eliza M; Chaves, Marcia A; Silva, Claudia M; Dias, Lucia F; Gomes, Sandra T M; Souza, Nilson E; Matsushita, Makoto

    2015-03-30

    Hamburger is a meat-based food that is easy to prepare and is widely consumed. It can be enriched using different ingredients, such as chia's by-product, which is rich in omega-3. Chemometrics is a very interesting tool to assess the influence of ingredients in the composition of foods. A complete factorial design 2(2) (two factors in two levels) with duplicate was performed to investigate the influence of the factors (1) concentration of textured soy proteins (TSP) and (2) concentration of chia flour partially defatted (CFPD) as a partial replacement for the bovine meat and porcine fat mix in hamburgers. The results of proximal composition, lipid oxidation, fatty acids sums, ratios, and nutritional indexes were used to propose statistical models. The factors TSP and CFPD were significant, and the increased values contributed to improve the composition in fatty acids, crude protein, and ash. Principal components analysis distinguished the samples with a higher content of chia. In desirability analysis, the highest level of TSP and CFPD was described as the optimal region, and it was not necessary to make another experimental point. The addition of chia's by-product is an alternative to increase the α-linolenic contents and to obtain nutritionally balanced food. © 2014 Society of Chemical Industry.

  7. Beneficial use of industrial by-products for phytoremediation of an arsenic-rich soil from a gold mining area.

    Science.gov (United States)

    Lopes, G; Ferreira, P A A; Pereira, F G; Curi, N; Rangel, W M; Guilherme, L R G

    2016-08-02

    This study investigated two industrial by-products - red mud (RM) and its mixture with phosphogypsum (RMG), as amendments in an As((5+))-contaminated soil from a gold mining area in Brazil in order to grow three plant species: Brachiaria decumbens, Crotalaria spectabilis, and Stylosanthes cv. Campo Grande. These amendments were applied to reach a soil pH of 6.0. Using RM and RMG increased shoot dry matter (SDM) and root dry matter (RDM) of most plants, with RMG being more effective. Adding RMG increased the SDM of Brachiaria and Crotalaria by 18 and 25% and the RDM by 25 and 12%, respectively. Stylosanthes was sensitive to As toxicity and grew poorly in all treatments. Arsenic concentration in shoots of Brachiaria and Crotalaria decreased by 26% with the use of RMG while As in roots reduced by 11 and 30%, respectively. Also, the activities of the plant oxidative stress enzymes varied following treatments with the by-products. The plants grew in the As-contaminated soil from the gold mining area. Thus, they might be employed for phytoremediation purposes, especially with the use of RMG due to its potential advantage in terms of nutrient supply (Ca(2+) and SO4(2-) from phosphogypsum).

  8. Atmospheric Infrared Radiance Variability.

    Science.gov (United States)

    1981-05-27

    ATMOSPHERIC VARIABILITY ON INFRARED RADIANCE PREDICTIONS - T. C. Degges 53 5. ATMOSPHERIC STRUCTURE - C.H. HLmphrey, C.R. Philbrick, S.M. Silverman , T.F. Tuan...variations similar to those shown in Figure 2. In arctic and subarctic regions, sudden warmings and coolings of the winter stratosphere and mesosphere... Silverman \\Jr I",rre. (;.L~~sIalmratorN Hanscom Air Force Base, Manss. T.F. Tuan Universitv of Cincinnati Cincinnati, (tio M. Anapol S.S.G.. Inc. Waltham

  9. Atmosphere and Heritage

    DEFF Research Database (Denmark)

    Ventzel Riis, Nina

    2012-01-01

    -between of the materials. This is what we identify as atmosphere, an enveloping phenomenon that surrounds and affects our sensuous system and well-being when we approach, enter, stay or move in a building. When we leave the building again we carry this atmospheric multi-sensory experience with us without adequate methods...... to describe and document it. In this paper I will introduce both new and traditional approaches to document the architectural heritage with the final conclusion to describe both tangible and intangible values, it requires an objective and geometrical approach as well as a subjective and phenomenological...

  10. 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 the...

  11. Hazard Analysis and identification of Critical Control Points of collagen extraction from cod by-products

    NARCIS (Netherlands)

    Aalberts, C.H.J.

    2004-01-01

    The aim of the European research project “UTILISATION AND STABILISATION OF BY-PRODUCTS FROM COD SPECIES” (QLK1-CT-2000-01017 QLRT-2001-02829) is to investigate whether collagen from fish by-products could serve as an important raw material in high quality food. Since Atlantic cod is a major

  12. 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...... and improving the success rate of aptamer selection....

  13. 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.

  14. 40 CFR Table 1 to Subpart C - VOC Content Limits by Product Category

    Science.gov (United States)

    2010-07-01

    ... 40 Protection of Environment 5 2010-07-01 2010-07-01 false VOC Content Limits by Product Category..., Table 1 Table 1 to Subpart C—VOC Content Limits by Product Category Product category VOC content limit (weight-percent VOC) Air fresheners: Single-phase 70 Double-phase 30 Liquids/pump sprays 18 Solids/gels 3...

  15. Approach for a pro-active emerging risk system on biofuel by-products in feed

    NARCIS (Netherlands)

    Asselt, van E.D.; Meuwissen, M.P.M.; Asseldonk, van M.A.P.M.; Sterrenburg, P.; Mengelers, M.J.B.

    2011-01-01

    Worldwide biofuel products have rapidly entered the market and consequently so did the availability of their by-products for feed production. A pro-active emerging risk system for biofuel by-products is essential in order to prevent the occurrence of emerging hazards in feed and livestock

  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

  17. An assessment of surface properties and moisture uptake of nonwoven fabrics from ginning by-products

    Science.gov (United States)

    Greige (raw) cotton by-products resulting from cotton ginning and mill processes have long been bleached for using them in absorbent nonwoven products. Other than that, the greige cotton by-products mostly had limited material applications, and used as an alternative feedstock for biomass and as a ...

  18. Improvement in the nutritive quality of cassava and its by-products ...

    African Journals Online (AJOL)

    STORAGESEVER

    2008-12-29

    Dec 29, 2008 ... A review of the extent of fermentation of cassava and its by-products was made in order to highlight the role played by fermentation on the bio-conversion of cassava and cassava by-products for improved nutrient quality. The reasons for cassava products fermentation mentioned were synonymous with the.

  19. Mango (Mangifera indica L.) by-products and their valuable components: a review.

    Science.gov (United States)

    Jahurul, M H A; Zaidul, I S M; Ghafoor, Kashif; Al-Juhaimi, Fahad Y; Nyam, Kar-Lin; Norulaini, N A N; Sahena, F; Mohd Omar, A K

    2015-09-15

    The large amount of waste produced by the food industries causes serious environmental problems and also results in economic losses if not utilized effectively. Different research reports have revealed that food industry by-products can be good sources of potentially valuable bioactive compounds. As such, the mango juice industry uses only the edible portions of the mangoes, and a considerable amount of peels and seeds are discarded as industrial waste. These mango by-products come from the tropical or subtropical fruit processing industries. Mango by-products, especially seeds and peels, are considered to be cheap sources of valuable food and nutraceutical ingredients. The main uses of natural food ingredients derived from mango by-products are presented and discussed, and the mainstream sectors of application for these by-products, such as in the food, pharmaceutical, nutraceutical and cosmetic industries, are highlighted. Copyright © 2015 Elsevier Ltd. All rights reserved.

  20. Worldwide trend of atmospheric mercury since 1995

    Directory of Open Access Journals (Sweden)

    F. Slemr

    2011-05-01

    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 concentrations 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 years is unusually large among most atmospheric trace gases and is at odds with the current mercury emission inventories with nearly constant anthropogenic emissions over this period. This 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. Acidification of oceans, climate change, excess nutrient input and pollution may also contribute by their impact on the biogeochemistry of ocean and soils. 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.

  1. Characterization of metformin by-products under photolysis, photocatalysis, ozonation and chlorination by high-performance liquid chromatography coupled to high-resolution mass spectrometry.

    Science.gov (United States)

    Quintão, Frederico Jehár Oliveira; Freitas, Julia Raquel Lino; de Fátima Machado, Célia; Aquino, Sérgio Francisco; de Queiroz Silva, Silvana; de Cássia Franco Afonso, Robson José

    2016-11-15

    Metformin (MTF) is the most widely prescribed drug for the treatment of patients with type 2 diabetes. Studies involving the removal of MTF from aqueous solutions and detailed information regarding the overall degradation process are scarce. The degradation of MTF in aqueous solution induced by direct photolysis, photocatalysis, ozonation and chlorination was evaluated. The process was continuously monitored focusing on the identification and monitoring of the by-products formed by applying high-performance liquid chromatography coupled to high-resolution mass spectrometry in positive ion mode. The cytotoxicity of metformin by-products was evaluated with an MTT assay. The results from the chlorination and ozonation tests indicate metformin removal efficiencies of 60% after 30 min of exposure. On the other hand, direct photolysis (UV-C) and heterogeneous photocatalysis (TiO2 /UV-C) led to a lower degree of metformin degradation, with removal efficiencies of 9.2% and 31%, respectively, after 30 min of exposure. The mineralization rates varied from 20% for ozonation to 0.72% for photolysis, thereby indicating there was accumulation of degradation by-products in all experiments. Mass spectrometric analysis indicated the presence of five metformin by-products. It was not possible to identify any by-product generated in the photolysis, and, in all oxidative assays, the treated samples were nontoxic to HepG2 cells. It is also observed that all systems exhibited low mineralization rates, with the chlorination process being slightly more efficient in promoting the degradation, whereas the ozonation was more efficient in promoting the mineralization of metformin. Based on these results a route for the chlorination, photodegradation and ozonation of MTF, which comprised of its successive oxidation in the aqueous medium, could be proposed. It could also be concluded that the treated samples were not cytotoxic to HepG2 cells in a MTT assay. Copyright © 2016 John Wiley & Sons

  2. Integrated Disinfection By-Products Mixtures Research: Concentration by Reverse Osmosis Membrane Techniques of Disinfection By-Products from Water Disinfected by Chlorination and Ozonation/Postchlorination

    Science.gov (United States)

    To conduct the health-effect studies described in subsequent articles in this series, concentrated aqueous mixtures of disinfection by-products were required for the two water treatment trains described in the preceding article (Miltner et al., 2008). To accomplish this, the fini...

  3. Biochars made from agro-industrial by-products remove chlorine and lower water toxicity

    Science.gov (United States)

    Tzachristas, Andreas; Xirou, Maria; Manariotis, Ioannis D.; Dailianis, Stefanos; Karapanagioti, Hrissi K.

    2016-04-01

    Chlorination is the most common disinfection process for water and treated wastewater. For the industrial use of water in food production, chlorine can add undesired taste and odor to the final product. For this reason, dechlorination is desired for food industries that use municipal tap water. For treated wastewater discharge or reuse, chlorine can be toxic to the receiving aqueous systems and to the irrigated plants. In both the above cases, dechlorination is also required. Traditionally activated carbon has been used as the ideal material for the removal of chlorine. The main mechanisms that describe the interaction between activated carbon and HOCl or OCl- are described by the following equations (AWWA, 1990): HOCl + C* → C*O + H+ + Cl- (1), OCl- + C* → C*O + Cl- (2) Where C* and C*O represent the activated carbon surface and a surface oxide, respectively. The present study proposes the use of agro-industrial by-products for the production of biochars that will be used for dechlorination of tap-water used for food-industry production. Different raw materials such as malt spent rootlets, coffee residue, olive and grape seeds, etc. are used for the production of biochar. Various temperatures and air-to-solid ratios are tested for optimizing biochar production. Batch tests as well as a column test are employed to study the dechlorination efficiency and kinetics of the different raw and biochar materials as well as those of commercial activated carbons. As chlorine concentration increases the removal also increases linearily. After 1 and 24 hours of contact the chlorine relative removal efficiencies for the biochar made from olive seeds are 50 and 77 ± 4%, respectively. It seems that the removal kinetics are faster during the first hour; then, removal continues but with a slower rate. Most of the biochars tested (with 3 mg of solid in 20 mL of chlorine solution at initial concentration Co=1.5 mg/L) demonstrated removal efficiencies with an average of 9.4 ± 0

  4. Astronomy and Atmospheric Optics

    Science.gov (United States)

    Cowley, Les; Gaina, Alex

    2011-12-01

    The authors discusse the insuccess of the observation of the Total Eclipse of the Moon from 10 december 2011 in Romania and relate them with meteoconditions. Only a very short part of the last penumbral phase was observed, while the inital part and the totality was not observed due to very dense clouds. The change in color and brightness during this phase was signaled. Meanwhile, there is an area of science where clouds are of great use and interest. This area is Atmospheric optics, while the science which study clouds is meteorology. Clouds in combination with Solar and Moon light could give rise to a variety of strange, rare and unobvious phenomena in the atmosphere (sky), sometimes confused with Unidentified Flying Objects (UFO). The importance of meteorology for astronomy and atmospheric optics is underlined and an invitation to astronomers to use unfavourable days for athmospheric observations was sent. The web address of the site by Les Cowley, designed for atmospheric optics phenomena is contained in the text of the entry.

  5. Results from atmospheric neutrinos

    Indian Academy of Sciences (India)

    With the announcement of new evidence for muon neutrino disappearance observed by the super-Kamiokande experiment, the more than a decade old atmospheric neutrino anomaly moved from a possible indication for neutrino oscillations to an apparently inescapable fact. The evidence is reviewed, and new indications ...

  6. ESA Atmospheric Toolbox

    Science.gov (United States)

    Niemeijer, Sander

    2017-04-01

    The ESA Atmospheric Toolbox (BEAT) is one of the ESA Sentinel Toolboxes. It consists of a set of software components to read, analyze, and visualize a wide range of atmospheric data products. In addition to the upcoming Sentinel-5P mission it supports a wide range of other atmospheric data products, including those of previous ESA missions, ESA Third Party missions, Copernicus Atmosphere Monitoring Service (CAMS), ground based data, etc. The toolbox consists of three main components that are called CODA, HARP and VISAN. CODA provides interfaces for direct reading of data from earth observation data files. These interfaces consist of command line applications, libraries, direct interfaces to scientific applications (IDL and MATLAB), and direct interfaces to programming languages (C, Fortran, Python, and Java). CODA provides a single interface to access data in a wide variety of data formats, including ASCII, binary, XML, netCDF, HDF4, HDF5, CDF, GRIB, RINEX, and SP3. HARP is a toolkit for reading, processing and inter-comparing satellite remote sensing data, model data, in-situ data, and ground based remote sensing data. The main goal of HARP is to assist in the inter-comparison of datasets. By appropriately chaining calls to HARP command line tools one can pre-process datasets such that two datasets that need to be compared end up having the same temporal/spatial grid, same data format/structure, and same physical unit. The toolkit comes with its own data format conventions, the HARP format, which is based on netcdf/HDF. Ingestion routines (based on CODA) allow conversion from a wide variety of atmospheric data products to this common format. In addition, the toolbox provides a wide range of operations to perform conversions on the data such as unit conversions, quantity conversions (e.g. number density to volume mixing ratios), regridding, vertical smoothing using averaging kernels, collocation of two datasets, etc. VISAN is a cross-platform visualization and

  7. Atmospheric energy for subsurface life on Mars?

    Science.gov (United States)

    Weiss, B. P.; Yung, Y. L.; Nealson, K. H.

    2000-01-01

    The location and density of biologically useful energy sources on Mars will limit the biomass, spatial distribution, and organism size of any biota. Subsurface Martian organisms could be supplied with a large energy flux from the oxidation of photochemically produced atmospheric H(2) and CO diffusing into the regolith. However, surface abundance measurements of these gases demonstrate that no more than a few percent of this available flux is actually being consumed, suggesting that biological activity driven by atmospheric H(2) and CO is limited in the top few hundred meters of the subsurface. This is significant because the available but unused energy is extremely large: for organisms at 30-m depth, it is 2,000 times previous estimates of hydrothermal and chemical weathering energy and far exceeds the energy derivable from other atmospheric gases. This also implies that the apparent scarcity of life on Mars is not attributable to lack of energy. Instead, the availability of liquid water may be a more important factor limiting biological activity because the photochemical energy flux can only penetrate to 100- to 1,000-m depth, where most H(2)O is probably frozen. Because both atmospheric and Viking lander soil data provide little evidence for biological activity, the detection of short-lived trace gases will probably be a better indicator of any extant Martian life.

  8. Biochars made from agro-industrial by-products remove chlorine from water and wastewater

    Science.gov (United States)

    Tzachristas, Andreas; Manariotis, Ioannis D.; Karapanagioti, Hrissi K.

    2017-04-01

    Chlorination is the most common disinfection process for water and wastewater. For the industrial use of water in food production, chlorine can add undesired taste and odor to the final product. For this reason, dechlorination is desired for food industries that use municipal tap water. For treated wastewater discharge or reuse, chlorine can be toxic to the receiving aqueous systems and to the irrigated plants. In both the above cases, dechlorination is also required. Traditionally activated carbon has been used as the ideal material for the removal of chlorine. The main mechanisms that describe the interaction between activated carbon and HOCl or OCl- are described by the following equations (AWWA, 1990): HOCl + C* → C*O + H+ + Cl- (1), OCl- + C* → C*O + Cl- (2) Where C* and C*O represent the activated carbon surface and a surface oxide, respectively. The present study proposes the use of agro-industrial by-products for the production of biochars that will be used for dechlorination of tap-water used for food-industry production. Different raw materials such as malt spent rootlets, coffee residue, olive and grape seeds, etc. are used for the production of biochar. Various temperatures and air-to-solid ratios are tested for optimizing biochar production. Batch tests as well as a column test are employed to study the dechlorination kinetics of the different raw and biochar materials as well as those of commercial activated carbons. The removal kinetics are faster during the first hour; then, removal continues but with a slower rate. Most of the biochars tested (with 3 mg of solid in 20 mL of chlorine solution at initial concentration Co=1.5 mg/L) demonstrated removal efficiencies with an average of 9.4 ± 0.5 mg/g. For the two commercial activated carbons, removal efficiencies were 11.4 ± 0.2 mg/g. The first-order constant k1 ranged between 0.001 and 0.014 (min-1) for the biosorbents and the biochars and it was equal to 0.017 (min-1) for the commercial

  9. Mars Atmospheric Capture and Gas Separation

    Science.gov (United States)

    Muscatello, Anthony; Santiago-Maldonado, Edgardo; Gibson, Tracy; Devor, Robert; Captain, James

    2011-01-01

    The Mars atmospheric capture and gas separation project is selecting, developing, and demonstrating techniques to capture and purify Martian atmospheric gases for their utilization for the production of hydrocarbons, oxygen, and water in ISRU systems. Trace gases will be required to be separated from Martian atmospheric gases to provide pure C02 to processing elements. In addition, other Martian gases, such as nitrogen and argon, occur in concentrations high enough to be useful as buffer gas and should be captured as welL To achieve these goals, highly efficient gas separation processes will be required. These gas separation techniques are also required across various areas within the ISRU project to support various consumable production processes. The development of innovative gas separation techniques will evaluate the current state-of-the-art for the gas separation required, with the objective to demonstrate and develop light-weight, low-power methods for gas separation. Gas separation requirements include, but are not limited to the selective separation of: (1) methane and water from un-reacted carbon oxides (C02- CO) and hydrogen typical of a Sabatier-type process, (2) carbon oxides and water from unreacted hydrogen from a Reverse Water-Gas Shift process, (3) carbon oxides from oxygen from a trash/waste processing reaction, and (4) helium from hydrogen or oxygen from a propellant scavenging process. Potential technologies for the separations include freezers, selective membranes, selective solvents, polymeric sorbents, zeolites, and new technologies. This paper and presentation will summarize the results of an extensive literature review and laboratory evaluations of candidate technologies for the capture and separation of C02 and other relevant gases.

  10. Quantification of bioactive compounds in pulps and by-products of tropical fruits from Brazil.

    Science.gov (United States)

    Ribeiro da Silva, Larissa Morais; Teixeira de Figueiredo, Evania Altina; Silva Ricardo, Nagila Maria Pontes; Pinto Vieira, Icaro Gusmao; Wilane de Figueiredo, Raimundo; Brasil, Isabella Montenegro; Gomes, Carmen L

    2014-01-15

    This study aimed to quantify the levels of resveratrol, coumarin, and other bioactives in pulps and by-products of twelve tropical fruits from Brazil obtained during pulp production process. Pineapple, acerola, monbin, cashew apple, guava, soursop, papaya, mango, passion fruit, surinam cherry, sapodilla, and tamarind pulps were evaluated as well as their by-products (peel, pulp's leftovers, and seed). Total phenolic, anthocyanins, yellow flavonoids, β-carotene and lycopene levels were also determined. Resveratrol was identified in guava and surinam cherry by-products and coumarin in passion fruit, guava and surinam cherry by-products and mango pulp. These fruit pulp and by-products could be considered a new natural source of both compounds. Overall, fruit by-products presented higher (P<0.05) bioactive content than their respective fruit pulps. This study provides novel information about tropical fruits and their by-products bioactive composition, which is essential for the understanding of their nutraceutical potential and future application in the food industry. Published by Elsevier Ltd.

  11. The Potential of Animal By-Products in Food Systems: Production, Prospects and Challenges

    Directory of Open Access Journals (Sweden)

    Babatunde O. Alao

    2017-06-01

    Full Text Available The consumption of animal by-products has continued to witness tremendous growth over the last decade. This is due to its potential to combat protein malnutrition and food insecurity in many countries. Shortly after slaughter, animal by-products are separated into edible or inedible parts. The edible part accounts for 55% of the production while the remaining part is regarded as inedible by-products (IEBPs. These IEBPs can be re-processed into sustainable products for agricultural and industrial uses. The efficient utilization of animal by-products can alleviate the prevailing cost and scarcity of feed materials, which have high competition between animals and humans. This will also aid in reducing environmental pollution in the society. In this regard, proper utilization of animal by-products such as rumen digesta can result in cheaper feed, reduction in competition and lower cost of production. Over the years, the utilization of animal by-products such as rumen digesta as feed in livestock feed has been successfully carried out without any adverse effect on the animals. However, there are emerging gaps that need to be further addressed regarding the food security and sustainability of the products. Therefore, the objective of this review highlights the efficacy and effectiveness of using animal by-products as alternative sources of feed ingredients, and the constraints associated with their production to boost livestock performance in the industry at large.

  12. An Overview of the Utilisation of Brewery By-Products as Generated by British Craft Breweries

    Directory of Open Access Journals (Sweden)

    Clare Kerby

    2017-06-01

    Full Text Available There is a wide range of information available on by-product disposal methods used by large national breweries. However, little information is available on the methods of by-product disposal used by craft breweries. An investigation was carried out in which 200+ British craft brewers were contacted, of which 90 craft brewers provided basic information about their brewery operations and by-product disposal. Representatives of eleven breweries were interviewed to provide an in-depth case study of their by-product disposal methods. The research found that urban craft brewers use a wider range of disposal methods compared to rural craft brewers; urban brewers dispose of more waste through sewage and landfill, as well as using external companies, such as bio-recycling and anaerobic digester plants, whereas rural brewers have relationships with farmers who dispose of the by-products in various ways. Craft brewers tend to have a direct relationship with the by-product users. Even though they do not have all disposal options available to them which the large industrial breweries have, due to their small scale of by-product production, craft brewers appear to find alternative means of sustainability.

  13. Ultrasound-assisted activation of zero-valent magnesium for nitrate denitrification: identification of reaction by-products and pathways.

    Science.gov (United States)

    Ileri, Burcu; Ayyildiz, Onder; Apaydin, Omer

    2015-07-15

    Zero-valent magnesium (Mg(0)) was activated by ultrasound (US) in an aim to promote its potential use in water treatment without pH control. In this context, nitrate reduction was studied at batch conditions using various doses of magnesium powder and ultrasound power. While neither ultrasound nor zero-valent magnesium alone was effective for reducing nitrate in water, their combination removed up to 90% of 50 mg/L NO3-N within 60 min. The rate of nitrate reduction by US/Mg(0) enhanced with increasing ultrasonic power and magnesium dose. Nitrogen gas (N2) and nitrite (NO2(-)) were detected as the major reduction by-products, while magnesium hydroxide Mg(OH)2 and hydroxide ions (OH(-)) were identified as the main oxidation products. The results from SEM-EDS measurements revealed that the surface oxide level decreased significantly when the samples of Mg(0) particles were exposed to ultrasonic treatment. The surface passivation of magnesium particles was successfully minimized by mechanical forces of ultrasound, which in turn paved the way to sustain the catalyst activity toward nitrate reduction. Copyright © 2015 Elsevier B.V. All rights reserved.

  14. Sodic soils reclaimed with by-product from flue gas desulfurization: corn production and soil quality.

    Science.gov (United States)

    Chun, S; Nishiyama, M; Matsumoto, S

    2001-01-01

    Interest is growing in the use of by-product from flue gas desulfurization (FGD) to reclaim sodic soils by controlling the pH and excessive Na+. This study evaluated the effects on corn (Zea mays) production and pH and electrical conductivity (EC) of calcareous sodic soil during four times of cultivation when the by-product was applied once at the first cultivation (Study I) and the impacts on plant and soil quality at first cultivation when the by-product was applied to the soil at 23,000 kg ha-1 (Study II). In Study I, the germination rate and corn production increased by applying the by-product (0, 5,800, 11,600, and 23,100 kg ha-1), and the greatest total amounts of corn production during the four times of cultivation was when the by-product was applied at 23,100 kg ha-1. In Study II, the pH, exchangeable sodium percentage (ESP), clay dispersion and soluble Na+ in the soil decreased and soluble Mg2+ and soluble K+ in the soil increased. The soil pH was reduced from 9.0 to 7.7 by applying the by-product. However, the by-product decreased the concentrations of total N and P in corn leaves in this study. No significant difference in the concentrations of Mo, Zn, Pb, Ni, Cd, Mn, Cr, Cu, and Al in corn leaves and the soil was observed between the by-product addition and the control except for B in the soil and Fe in corn leaves. The concentration of B in the soil was reduced from 28.7 mg kg-1 to 25.4 mg kg-1 and the concentration of Fe in corn leaves increased from 17.5 mg kg-1 to 22.6 mg kg-1 by applying the by-product in our study.

  15. Multi-model study of mercury dispersion in the atmosphere: atmospheric processes and model evaluation

    Science.gov (United States)

    Travnikov, Oleg; Angot, Hélène; Artaxo, Paulo; Bencardino, Mariantonia; Bieser, Johannes; D'Amore, Francesco; Dastoor, Ashu; De Simone, Francesco; Diéguez, María del Carmen; Dommergue, Aurélien; Ebinghaus, Ralf; Feng, Xin Bin; Gencarelli, Christian N.; Hedgecock, Ian M.; Magand, Olivier; Martin, Lynwill; Matthias, Volker; Mashyanov, Nikolay; Pirrone, Nicola; Ramachandran, Ramesh; Read, Katie Alana; Ryjkov, Andrei; Selin, Noelle E.; Sena, Fabrizio; Song, Shaojie; Sprovieri, Francesca; Wip, Dennis; Wängberg, Ingvar; Yang, Xin

    2017-04-01

    Current understanding of mercury (Hg) behavior in the atmosphere contains significant gaps. Some key characteristics of Hg processes, including anthropogenic and geogenic emissions, atmospheric chemistry, and air-surface exchange, are still poorly known. This study provides a complex analysis of processes governing Hg fate in the atmosphere involving both measured data from ground-based sites and simulation results from chemical transport models. A variety of long-term measurements of gaseous elemental Hg (GEM) and reactive Hg (RM) concentration as well as Hg wet deposition flux have been compiled from different global and regional monitoring networks. Four contemporary global-scale transport models for Hg were used, both in their state-of-the-art configurations and for a number of numerical experiments to evaluate particular processes. Results of the model simulations were evaluated against measurements. As follows from the analysis, the interhemispheric GEM gradient is largely formed by the prevailing spatial distribution of anthropogenic emissions in the Northern Hemisphere. The contributions of natural and secondary emissions enhance the south-to-north gradient, but their effect is less significant. Atmospheric chemistry has a limited effect on the spatial distribution and temporal variation of GEM concentration in surface air. In contrast, RM air concentration and wet deposition are largely defined by oxidation chemistry. The Br oxidation mechanism can reproduce successfully the observed seasonal variation of the RM / GEM ratio in the near-surface layer, but it predicts a wet deposition maximum in spring instead of in summer as observed at monitoring sites in North America and Europe. Model runs with OH chemistry correctly simulate both the periods of maximum and minimum values and the amplitude of observed seasonal variation but shift the maximum RM / GEM ratios from spring to summer. O3 chemistry does not predict significant seasonal variation of Hg

  16. Atmospheric pressure plasma jet applications

    Energy Technology Data Exchange (ETDEWEB)

    Park, J.; Herrmann, H.W.; Henins, I.; Selwyn, G.S. [Los Alamos National Lab., NM (United States)

    1998-12-31

    The atmospheric pressure plasma jet (APPJ) is a non-thermal, high pressure plasma discharge that produces a high velocity effluent stream of highly reactive chemical species. The discharge operates on a feedstock gas (e.g., He/O2/H2O) which flows between two concentric cylindrical electrodes: an outer grounded electrode and an inner electrode powered at 13.56 MHz RF. While passing through the plasma, the feedgas becomes excited, ionized or dissociated by electron impact. The fast-flowing effluent consists of ions and electrons, which are rapidly lost by recombination, highly reactive radicals (e.g., O, OH), and metastable species (e.g., O2). The metastable O2, which is reactive to hydrocarbon and other organic species, has been observed through optical emission spectroscopy to decrease by a factor of 2 from the APPJ nozzle exit to a distance of 10 cm. Unreacted metastable O2, and that which does not impinge on a surface, will then decay back to ordinary ground state O2, resulting in a completely dry, environmentally-benign form of surface cleaning. Applications such as removal of photoresist, oxide films and organic residues from wafers for the electronics industry, decontamination of civilian and military areas and personnel exposed to chemical or biological warfare agents, and paint (e.g., graffiti) removal are being considered.

  17. Aspects of the atmospheric chemistry of amides.

    Science.gov (United States)

    Barnes, Ian; Solignac, Geraldine; Mellouki, Abdelwahid; Becker, Karl H

    2010-12-17

    The gas-phase reactions of six amides, formamide, N-methyl formamide, N,N-dimethyl formamide, acetamide, N-methyl acetamide and N,N-dimethyl acetamide with the atmospheric oxidants OH radicals and Cl atoms, but in a number of cases also with NO(3) radicals and ozone, are presented and discussed. Kinetic and mechanistic information available from previous experimental work is combined with new kinetic and product information from this study, obtained in a photoreactor using in situ FTIR spectrometry, to elucidate the gas-phase photooxidation mechanisms of the amides and assess potential environmental implications.

  18. Landslide remediation on Ohio State Route 83 using clean coal combustion by-products

    Energy Technology Data Exchange (ETDEWEB)

    Payette, R. [Ohio Dept. of Transportation, Jacksontown, OH (United States); Chen, Xi You; Wolfe, W. [Ohio State Univ., Columbus, OH (United States); Beeghly, J. [Dravo Lime Co., Pittsburgh, PA (United States)

    1995-12-31

    The disposal of flue gas desulfurization (FGD) by-products has become a major concern as issues of emission cleansing and landfill costs continue to rise. Laboratory tests conducted at the Ohio State University have shown that dry FGD by-products possess certain engineering properties that have proven desirable in a number of construction uses. As a follow on to the laboratory program, a field investigation into engineering uses of dry FGD wastes was initiated. In the present work, an FGD by-product was used to reconstruct the failed portion of a highway embankment. The construction process and the stability of the repaired embankment are examined.

  19. Atmospheric Level of SO2 in Sokoto Metropolis, Nigeria | Tsafe ...

    African Journals Online (AJOL)

    The concentration of atmospheric sulphur (IV) oxide in Sokoto Metropolis was determined by sucking air in hydrogen peroxide solution, followed by the photometric determination of the sulphates ion formed. The overall mean concentration obtained (0.270+-0.051 mg/m3) exceeds the recommended WHO daily guideline ...

  20. Electrolytic synthesis of ammonia in molten salts under atmospheric pressure.

    Science.gov (United States)

    Murakami, Tsuyoshi; Nishikiori, Tokujiro; Nohira, Toshiyuki; Ito, Yasuhiko

    2003-01-15

    Ammonia was successfully synthesized by using a new electrochemical reaction with high current efficiency at atmospheric pressure and at lower temperatures than the Haber-Bosch process. In this method, nitride ion (N3-), which is produced by the reduction from nitrogen gas at the cathode, is anodically oxidized and reacts with hydrogen to produce ammonia at the anode.

  1. Atmospheric pressure CVD of SNO2 and ZNO:AL

    NARCIS (Netherlands)

    Deelen, J. van; Kniknie, B.J.; Steijvers, H.L.A.H.; Mannie, G.; Thune, P.; Illiberi, A.

    2012-01-01

    Atmospheric pressure CVD (APCVD) is a highly cost effective method of depositing transparent conductive oxides (TCOs). In this work, insights in alcohol addition in the widely applied SnO2 process are discussed, including high resolution TEM images. Furthermore, the APCVD process of ZnO:Al was

  2. Spatial atmospheric atomic layer deposition of alxzn1-xo

    NARCIS (Netherlands)

    Illiberi, A.; Scherpenborg, R.; Wu, Y.; Roozeboom, F.; Poodt, P.

    2013-01-01

    The possibility of growing multicomponent oxides by spatial atmospheric atomic layer deposition has been investigated. To this end, Al xZn1-xO films have been deposited using diethyl zinc (DEZ), trimethyl aluminum (TMA), and water as Zn, Al, and O precursors, respectively. When the metal precursors

  3. Chapter 4 Gaseous Elemental Mercury in the Ambient Atmosphere

    DEFF Research Database (Denmark)

    Ariya, Parisa A.; Skov, Henrik; Grage, Mette M L

    2008-01-01

    Understanding the kinetics and mechanisms associated with the atmospheric chemistry of mercury is of great importance to protecting the environment. This review will focus on theoretical calculations to advance understanding of gas phase oxidation of gaseous elemental mercury (GEM) by halogen spe...

  4. Atmospheric chemistry of CH3CHF2 (HFC-152a)

    DEFF Research Database (Denmark)

    Taketani, Fumikazu; Nakayama, Tomoki; Takahashi, Kenshi

    2005-01-01

    Smog chamber/Fourier transform infrared (FTIR) and laser-induced fluorescence (LIF) spectroscopic techniques were used to study the atmospheric degradation of CH3CHF2. The kinetics and products of the Cl(2P(3/2)) (denoted Cl) atom- and the OH radical-initiated oxidation of CH3CHF2 in 700 Torr...

  5. LBA-ECO TG-06 Vertical Profiles of Atmospheric Trace Gases over the Amazon Basin

    Data.gov (United States)

    National Aeronautics and Space Administration — This data set contains measurements of atmospheric carbon dioxide (CO2), methane (CH4), carbon monoxide (CO), hydrogen (H2), nitrous oxide (N2O), and sulfur...

  6. CARVE: L2 Atmospheric Gas Concentrations, Airborne Flasks, Alaska, 2012-2015

    Data.gov (United States)

    National Aeronautics and Space Administration — This data set provides atmospheric carbon dioxide (CO2), methane (CH4), carbon monoxide (CO), molecular hydrogen (H2), nitrous oxide (N2O), sulfur hexafluoride...

  7. LBA-ECO TG-06 Vertical Profiles of Atmospheric Trace Gases over the Amazon Basin

    Data.gov (United States)

    National Aeronautics and Space Administration — ABSTRACT: This data set contains measurements of atmospheric carbon dioxide (CO2), methane (CH4), carbon monoxide (CO), hydrogen (H2), nitrous oxide (N2O), and...

  8. Dynamics of Nitric Oxide and Nitrous Oxide Emission during Nitrogen Conversion Processes

    NARCIS (Netherlands)

    Kampschreur, M.J.

    2010-01-01

    Nitric oxide (NO) and nitrous oxide (N2O) emissions can be a serious threat to the environment. Rising levels of N2O in the atmosphere contribute to global warming and destruction of the ozone layer. This thesis describes an investigation on the emission of NO and N2O during nitrogen conversion

  9. Serum from postmenopausal women treated with a by-product of olive-oil extraction process stimulates osteoblastogenesis and inhibits adipogenesis in human mesenchymal stem-cells (MSC).

    Science.gov (United States)

    Casado-Díaz, Antonio; Túnez-Fiñana, Isaac; Mata-Granados, José María; Ruiz-Méndez, María Victoria; Dorado, Gabriel; Romero-Sánchez, María Concepción; Navarro-Valverde, Cristina; Quesada-Gómez, José Manuel

    2017-04-01

    Aging may enhance both oxidative stress and bone-marrow mesenchymal stem-cell (MSC) differentiation into adipocytes. That reduces osteoblastogenesis, thus favoring bone-mass loss and fracture, representing an important worldwide health-issue, mainly in countries with aging populations. Intake of antioxidant products may help to retain bone-mass density. Interestingly, a novel olive-pomace physical treatment to generate olive oil also yields by-products rich in functional antioxidants. Thus, diet of postmenopausal women was supplemented for two months with one of such by-products (distillate 6; D6), being rich in squalene. After treatment, serum from such women showed reduced both lipidic peroxidation and oxidized low-density lipoprotein (LDL). Besides, vitamin E and coenzyme Q10 levels increased. Furthermore, culture medium containing 10% of such serum both increased osteoblastogenesis and reduced adipogenesis in human MSC from bone marrow. Therefore, highly antioxidant by-products like D6 may represent a relevant source for development of functional products, for both prevention and treatment of degenerative pathologies associated with aging, like osteoporosis. Copyright © 2017 Elsevier Inc. All rights reserved.

  10. Applications of theoretical methods in atmospheric science

    DEFF Research Database (Denmark)

    Johnson, Matthew Stanley; Goodsite, Michael E.

    2008-01-01

    in addressing an issue of primary concern: understanding photochemical reaction rates at the various conditions found in the atmosphere. Atmospheric science includes both atmospheric chemistry and atmospheric physics, meteorology, climatology and the study of extraterrestrial atmospheres....

  11. Atmospheric lepton fluxes

    Directory of Open Access Journals (Sweden)

    Gaisser Thomas K.

    2015-01-01

    Full Text Available 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 νμ and νe are discussed, along with the implications of the muon charge ratio for the νµ / ν̅µ ratio. Methods to account for effects of the knee in the primary cosmic-ray spectrum and the energy-dependence of hadronic interactions on the neutrino fluxes are discussed and illustrated in the context of recent results from IceCube. A simple numerical/analytic method is proposed for systematic investigation of uncertainties in neutrino fluxes arising from uncertainties in the primary cosmic-ray spectrum/composition and hadronic interactions.

  12. Habituating alarming atmospheres

    DEFF Research Database (Denmark)

    Højlund, Marie

    This paper proposes embodied rhythmic sound habituation as a possible resource when designing contextualized technologies in critical atmospheres. The main contribution is collating the concept of rhythm as presented by Henri Lefebvre with the concept of sound habituation to help operationalize...... essential dynamic parameters when designing atmospheres. This research is based on the development of the novel research artefact Kidkit, designed for children, who are going to meet a hospitalized relative with fatal injuries in a Neuro–Intensive Care Unit. Sounds from hospital equipment have important...... functionality for the staff, but are stressful for visitors and patients, as they are designed to demand attention even though they have no direct functional meaning to them. By introducing sounds from the ward, integrated in the furniture as simple sound sample triggers, KidKit invites children to become...

  13. Atmosphere beyond Poetics

    DEFF Research Database (Denmark)

    Wieczorek, Izabela

    2014-01-01

    , the notion of atmosphere is presented as parallactic for designing experience in architectural fields, since it transgresses formal and material boundaries of bodies, opening a new gap that exposes the orthodox space-body-environment relationships to questions. It leads to the dissolution...... of the architectural ‘object’ and its fixity and offers a new understanding of context and space – approached as a field of dynamic relationships. It calls for a re-evaluation of perceptual experience, offering to architecture an expanded domain in which architecture manifests itself, including qualities – besides...... poetics and beauty – that architecture has long resisted. That is, it defines space as a contingent construction, performative and intensely affective. Accordingly, the intention is to critically analyse what the term atmosphere entails in architecture, and to expand its notion in terms of affective...

  14. Contaminants in the Atmosphere

    DEFF Research Database (Denmark)

    Skov, H.; Bossi, R.; Wåhlin, P.

    This report presents the results of atmospheric monitoring in Nuuk, Greenland. A long series of heavy metals and persistent organic Pollutants (POPs) have been measured and model calculations have been carried out supporting the interpretation of the results. Financially, the Danish Environmental...... Protection Agency supported this work with means from the MIKA/DANCEA funds for Environmental Support to the Arctic Region and the work is part of the Danish contribution to Arctic Monitoring and Assessment Programme, AMAP......This report presents the results of atmospheric monitoring in Nuuk, Greenland. A long series of heavy metals and persistent organic Pollutants (POPs) have been measured and model calculations have been carried out supporting the interpretation of the results. Financially, the Danish Environmental...

  15. Atmospheric Loss and Warming Of The Early Mars

    Science.gov (United States)

    Airapetian, V.; Gronoff, G.; Grocer, A.; Khazanov, G. V.; Hébrard, E.

    2016-12-01

    Today Mars represents an inhospitable world with a thin 6-mbar atmosphere that cannot support surface water. Current evidence suggests that the early Mars was a wet and at least somewhat warmer world that could support life. How hospitable Mars was for life? The atmospheric evolution of Mars over the last 4 billion years was affected by the rate of atmospheric loss and the chemical changes induced by space weather events from the evolving Sun and the planet's early outgassing history. We apply our atmospheric model enhanced with chemistry that describes photo-collisional dissociation and ionization of molecular nitrogen and carbon dioxide rich atmosphere of the early Mars due to XUV emission and penetration of energetic protons accelerated in extended shock waves driven by super Carrington events from the young Sun. We calculate the rate of atmospheric loss of oxygen ions from the atmosphere of early Mars to be 200 kg/s. This suggests that the early Martian atmosphere was subject to significant erosion, which implies the large rate of outgassing due to tectonic and volcanic activity. We also show that energetic protons produce multiple generations of secondary electrons that contribute to the destruction of N2 into reactive nitrogen, and the subsequent destruction of CO2 and CH4 efficiently producing N2O, a powerful greenhouse gas. The efficient production of nitrous oxide in the Martian troposphere can explain the longstanding problem of the Faint Young Sun paradox for Mars.

  16. Haze in Pluto's atmosphere

    Science.gov (United States)

    Cheng, A. F.; Summers, M. E.; Gladstone, G. R.; Strobel, D. F.; Young, L. A.; Lavvas, P.; Kammer, J. A.; Lisse, C. M.; Parker, A. H.; Young, E. F.; Stern, S. A.; Weaver, H. A.; Olkin, C. B.; Ennico, K.

    2017-07-01

    Haze in Pluto's atmosphere was detected in images by both the Long Range Reconnaissance Imager (LORRI) and the Multispectral Visible Imaging Camera (MVIC) on New Horizons. LORRI observed haze up to altitudes of at least 200 km above Pluto's surface at solar phase angles from ∼20° to ∼169°. The haze is structured with about ∼20 layers, and the extinction due to haze is greater in the northern hemisphere than at equatorial or southern latitudes. However, more haze layers are discerned at equatorial latitudes. A search for temporal variations found no evidence for motions of haze layers (temporal changes in layer altitudes) on time scales of 2 to 5 hours, but did find evidence of changes in haze scale height above 100 km altitude. An ultraviolet extinction attributable to the atmospheric haze was also detected by the ALICE ultraviolet spectrograph on New Horizons. The haze particles are strongly forward-scattering in the visible, and a microphysical model of haze is presented which reproduces the visible phase function just above the surface with 0.5 μm spherical particles, but also invokes fractal aggregate particles to fit the visible phase function at 45 km altitude and account for UV extinction. A model of haze layer generation by orographic excitation of gravity waves is presented. This model accounts for the observed layer thickness and distribution with altitude. Haze particles settle out of the atmosphere and onto Pluto's surface, at a rate sufficient to alter surface optical properties on seasonal time scales. Pluto's regional scale albedo contrasts may be preserved in the face of the haze deposition by atmospheric collapse.

  17. Recovery and characterization of by-products from egg processing plant wastewater using coagulants

    National Research Council Canada - National Science Library

    Xu, L J; Sheldon, B W; Carawan, R E; Larick, D K; Chao, A C

    2001-01-01

    ...%, respectively, for all coagulants tested. Protein and fat recoveries were over 95% for all coagulants. The optimal coagulant concentration for maximum by-product recovery depended on initial wastewater concentrations of protein, total solids, and fat...

  18. MULTISPECTRAL IDENTIFICATION OF CHLORINE DIOXIDE DISINFECTION BY-PRODUCTS IN DRINKING WATER

    Science.gov (United States)

    This paper discusses the identification of organic disinfection by-products (DBPs) at a pilot plant in Evansville, Indiana, that uses chlorine dioxide as a primary disinfectant. nconventional multispectral identification techniques (gas chromatography combined with high and low r...

  19. Incineration By-Products of AA2, NC Fines, and NG Slums

    National Research Council Canada - National Science Library

    Cropek, Donald

    2001-01-01

    ...) and associated energetic wastes (EW). Knowledge of the by-products from incineration is invaluable for the proper design of emission control systems and selection of operating parameters to ensure maximum destruction efficiency...

  20. SHORTER