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Sample records for oxidation products aromatics

  1. Selective Production of Aromatic Aldehydes from Heavy Fraction of Bio-oil via Catalytic Oxidation

    International Nuclear Information System (INIS)

    Li, Yan; Chang, Jie; Ouyang, Yong; Zheng, Xianwei

    2014-01-01

    High value-added aromatic aldehydes (e. g. vanillin and syringaldehyde) were produced from heavy fraction of bio-oil (HFBO) via catalytic oxidation. The concept is based on the use of metalloporphyin as catalyst and hydrogen peroxide (H 2 O 2 ) as oxidant under alkaline condition. The biomimetic catalyst cobalt(II)-sulfonated tetraphenylporphyrin (Co(TPPS 4 )) was prepared and characterized. It exhibited relative high activity in the catalytic oxidation of HFBO. 4.57 wt % vanillin and 1.58 wt % syringaldehyde were obtained from catalytic oxidation of HFBO, compared to 2.6 wt % vanillin and 0.86 wt % syringaldehyde without Co(TPPS 4 ). Moreover, a possible mechanism of HFBO oxidation using Co(TPPS 4 )/H 2 O 2 was proposed by the research of model compounds. The results showed that this is a promising and environmentally friendly method for production of aromatic aldehydes from HFBO under Co(TPPS 4 )/H 2 O 2 system

  2. Selective Production of Aromatic Aldehydes from Heavy Fraction of Bio-oil via Catalytic Oxidation

    Energy Technology Data Exchange (ETDEWEB)

    Li, Yan; Chang, Jie; Ouyang, Yong; Zheng, Xianwei [South China Univ. of Technology, Guangzhou (China)

    2014-06-15

    High value-added aromatic aldehydes (e. g. vanillin and syringaldehyde) were produced from heavy fraction of bio-oil (HFBO) via catalytic oxidation. The concept is based on the use of metalloporphyin as catalyst and hydrogen peroxide (H{sub 2}O{sub 2}) as oxidant under alkaline condition. The biomimetic catalyst cobalt(II)-sulfonated tetraphenylporphyrin (Co(TPPS{sub 4})) was prepared and characterized. It exhibited relative high activity in the catalytic oxidation of HFBO. 4.57 wt % vanillin and 1.58 wt % syringaldehyde were obtained from catalytic oxidation of HFBO, compared to 2.6 wt % vanillin and 0.86 wt % syringaldehyde without Co(TPPS{sub 4}). Moreover, a possible mechanism of HFBO oxidation using Co(TPPS{sub 4})/H{sub 2}O{sub 2} was proposed by the research of model compounds. The results showed that this is a promising and environmentally friendly method for production of aromatic aldehydes from HFBO under Co(TPPS{sub 4})/H{sub 2}O{sub 2} system.

  3. Catalytic wet-air oxidation of lignin in a three-phase reactor with aromatic aldehyde production

    Directory of Open Access Journals (Sweden)

    Sales F.G.

    2004-01-01

    Full Text Available In the present work a process of catalytic wet air oxidation of lignin obtained from sugar-cane bagasse is developed with the objective of producing vanillin, syringaldehyde and p-hydroxybenzaldehyde in a continuous regime. Palladium supported on g-alumina was used as the catalyst. The reactions in the lignin degradation and aldehyde production were described by a kinetic model as a system of complex parallel and series reactions, in which pseudo-first-order steps are found. For the purpose of producing aromatic aldehydes in continuous regime, a three-phase fluidized reactor was built, and it was operated using atmospheric air as the oxidizer. The best yield in aromatic aldehydes was of 12%. The experimental results were compatible with those values obtained by the pseudo-heterogeneous axial dispersion model (PHADM applied to the liquid phase.

  4. Influence of cooking methods and storage time on lipid and protein oxidation and heterocyclic aromatic amines production in bacon.

    Science.gov (United States)

    Soladoye, O P; Shand, P; Dugan, M E R; Gariépy, C; Aalhus, J L; Estévez, M; Juárez, M

    2017-09-01

    This study aimed to examine the influence of cooking methods and pre-determined refrigerated storage days on the production of lipid oxidation (TBARS), protein oxidation (PROTOX) and heterocyclic aromatic amines (HAA) in bacon. Forty-four pork bellies selected from pigs varying in breed, sex and diets to introduce variability in composition were processed as bacon. Sliced-bacon was stored at 4°C either for 2 or 28days and these storage groups were cooked either with microwave or frying pan. Microwave led to significantly higher PROTOX (P0.05) by the cooking methods and storage times. Similarly, the fatty acid composition of pork belly did not significantly influence the production of HAA, TBARS and PROTOX produced in bacon during cooking. Overall, microwave cooking had lesser impact on the production of carcinogenic compounds in bacon with only minor impact on sensory attributes. Copyright © 2017. Published by Elsevier Ltd.

  5. Determination of polycyclic aromatic hydrocarbons and their oxy-, nitro-, and hydroxy-oxidation products

    International Nuclear Information System (INIS)

    Cochran, R.E.; Dongari, N.; Jeong, H.; Beránek, J.; Haddadi, S.; Shipp, J.; Kubátová, A.

    2012-01-01

    Highlights: ► We describe a method for determining PAHs and their oxidation products. ► Solid-phase extraction was used to fractionate PAHs and their oxidation products. ► Gas chromatography–mass spectrometry methods were optimized. ► The developed method was applied to two particulate matter (PM) samples. - Abstract: A sensitive method has been developed for the trace analysis of PAHs and their oxidation products (i.e., nitro-, oxy-, and hydroxy-PAHs) in air particulate matter (PM). Following PM extraction, PAHs, nitro-, oxy-, and hydroxy-PAHs were fractionated using solid phase extraction (SPE) based on their polarities. Gas chromatography–mass spectrometry (GC–MS) conditions were optimized, addressing injection (i.e., splitless time), negative-ion chemical ionization (NICI) parameters, i.e., source temperature and methane flow rate, and MS scanning conditions. Each class of PAH oxidation products was then analyzed using the sample preparation and appropriate ionization conditions (e.g., nitro-PAHs exhibited the greatest sensitivity when analyzed with NICI–MS while hydroxy-PAHs required chemical derivatization prior to GC–MS analysis). The analyses were performed in selected-ion-total-ion (SITI) mode, combining the increased sensitivity of selected-ion monitoring (SIM) with the identification advantages of total-ion current (TIC). The instrumental LODs determined were 6–34 pg for PAHs, 5–36 pg for oxy-PAHs, and 1–21 pg for derivatized hydroxy-PAHs using electron ionization (GC-EI-MS). NICI–MS was found to be a useful tool for confirming the tentative identification of oxy-PAHs. For nitro-PAHs, LODs were 1–10 pg using negative-ion chemical ionization (GC-NICI-MS). The developed method was successfully applied to two types of real-world PM samples, diesel exhaust standard reference material (SRM 2975) and wood smoke PM.

  6. Sodium Perborate Oxidation of an Aromatic Amine

    Science.gov (United States)

    Juestis, Laurence

    1977-01-01

    Describes an experiment involving the oxidation of aromatic primary amines to the corresponding azo compound; suggests procedures for studying factors that influence the yield of such a reaction, including the choice of solvent and the oxidant-amine ratio. (MLH)

  7. Microbial production of the aromatic building-blocks (S)-styrene oxide and (R)-1,2-phenylethanediol from renewable resources.

    Science.gov (United States)

    McKenna, Rebekah; Pugh, Shawn; Thompson, Brian; Nielsen, David R

    2013-12-01

    (S)-Styrene oxide and (R)-1,2-phenylethanediol are chiral aromatic molecular building blocks used commonly as precursors to pharmaceuticals and other specialty chemicals. Two pathways have been engineered in Escherichia coli for their individual biosynthesis directly from glucose. The novel pathways each constitute extensions of the previously engineered styrene pathway, developed by co-expressing either styrene monooxygenase (SMO) or styrene dioxygenase (SDO) to convert styrene to (S)-styrene oxide and (R)-1,2-phenylethanediol, respectively. StyAB from Pseudomonas putida S12 was determined to be the most effective SMO. SDO activity was achieved using NahAaAbAcAd of Pseudomonas sp. NCIB 9816-4, a naphthalene dioxygenase with known broad substrate specificity. Production of phenylalanine, the precursor to both pathways, was systematically enhanced through a number of mutations, most notably via deletion of tyrA and over-expression of tktA. As a result, (R)-1,2-phenylethanediol reached titers as high as 1.23 g/L, and at 1.32 g/L (S)-styrene oxide titers already approach their toxicity limit. As with other aromatics, product toxicity was strongly correlated with a model of membrane accumulation and disruption. This study additionally demonstrates that greater flux through the styrene pathway can be achieved if its toxicity is addressed, as achieved in this case by reacting styrene to less toxic products. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  8. pH-Controlled Oxidation of an Aromatic Ketone: Structural Elucidation of the Products of Two Green Chemical Reactions

    Science.gov (United States)

    Ballard, C. Eric

    2010-01-01

    A laboratory experiment emphasizing the structural elucidation of organic compounds has been developed as a discovery exercise. The "unknown" compounds are the products of the pH-controlled oxidation of 4'-methoxyacetophenone with bleach. The chemoselectivity of this reaction is highly dependent on the pH of the reaction media: under basic…

  9. Aromatic-radical oxidation chemistry

    Energy Technology Data Exchange (ETDEWEB)

    Glassman, I.; Brezinsky, K. [Princeton Univ., NJ (United States)

    1993-12-01

    The research effort has focussed on discovering an explanation for the anomalously high CO{sub 2} concentrations observed early in the reaction sequence of the oxidation of cyclopentadiene. To explain this observation, a number of plausible mechanisms have been developed which now await experimental verification. One experimental technique for verifying mechanisms is to probe the reacting system by perturbing the radical concentrations. Two forms of chemical perturbation of the oxidation of cyclopentadiene were begun during this past year--the addition of NO{sub 2} and CO to the reacting mixture.

  10. Aromatics Oxidation and Soot Formation in Flames

    Energy Technology Data Exchange (ETDEWEB)

    Howard, J. B.; Richter, H.

    2005-03-29

    This project is concerned with the kinetics and mechanisms of aromatics oxidation and the growth process to polycyclic aromatic hydrocarbons (PAH) of increasing size, soot and fullerenes formation in flames. The overall objective of the experimental aromatics oxidation work is to extend the set of available data by measuring concentration profiles for decomposition intermediates such as phenyl, cyclopentadienyl, phenoxy or indenyl radicals which could not be measured with molecular-beam mass spectrometry to permit further refinement and testing of benzene oxidation mechanisms. The focus includes PAH radicals which are thought to play a major role in the soot formation process while their concentrations are in many cases too low to permit measurement with conventional mass spectrometry. The radical species measurements are used in critical testing and improvement of a kinetic model describing benzene oxidation and PAH growth. Thermodynamic property data of selected species are determined computationally, for instance using density functional theory (DFT). Potential energy surfaces are explored in order to identify additional reaction pathways. The ultimate goal is to understand the conversion of high molecular weight compounds to nascent soot particles, to assess the roles of planar and curved PAH and relationships between soot and fullerenes formation. The specific aims are to characterize both the high molecular weight compounds involved in the nucleation of soot particles and the structure of soot including internal nanoscale features indicative of contributions of planar and/or curved PAH to particle inception.

  11. Aromatics oxidation and soot formation in flames

    Energy Technology Data Exchange (ETDEWEB)

    Howard, J.B.; Pope, C.J.; Shandross, R.A.; Yadav, T. [Massachusetts Institute of Technology, Cambridge (United States)

    1993-12-01

    This project is concerned with the kinetics and mechanisms of aromatics oxidation and soot and fullerenes formation in flames. The scope includes detailed measurements of profiles of stable and radical species concentrations in low-pressure one-dimensional premixed flames. Intermediate species identifications and mole fractions, fluxes, and net reaction rates calculated from the measured profiles are used to test postulated reaction mechanisms. Particular objectives are to identify and to determine or confirm rate constants for the main benzene oxidation reactions in flames, and to characterize fullerenes and their formation mechanisms and kinetics.

  12. Oxidative decomposition of aromatic hydrocarbons by electron beam irradiation

    Science.gov (United States)

    Han, Do-Hung; Stuchinskaya, Tatiana; Won, Yang-Soo; Park, Wan-Sik; Lim, Jae-Kyong

    2003-05-01

    Decomposition of aromatic volatile organic compounds (VOCs) under electron beam irradiation was studied in order to examine the kinetics of the process, to characterize the reaction product distribution and to develop a process of waste gas control technology. Toluene, ethylbenzene, o-, m-, p-xylenes and chlorobenzene were used as target materials. The experiments were carried out at doses ranging from 0.5 to 10 kGy, using a flow reactor utilized under electron beam irradiation. Maximum degrees of decomposition carried out at 10 kGy in air environment were 55-65% for “non-chlorinated” aromatic VOC and 85% for chlorobenzene. It was found that a combination of aromatic pollutants with chlorobenzene would considerably increase the degradation value up to nearly 50% compared to the same compounds in the absence of chlorine groups. Based on our experimental observation, the degradation mechanism of the aromatic compounds combined with chloro-compound suggests that a chlorine radical, formed from EB irradiation, induces a chain reaction, resulting in an accelerating oxidative destruction of aromatic VOCs.

  13. Aromatic VOCs global influence in the ozone production

    Science.gov (United States)

    Cabrera-Perez, David; Pozzer, Andrea

    2016-04-01

    Aromatic hydrocarbons are a subgroup of Volatile Organic Compounds (VOCs) of special interest in the atmosphere of urban and semi-urban areas. Aromatics form a high fraction of VOCs, are highly reactive and upon oxidation they are an important source of ozone. These group of VOCs are released to the atmosphere by processes related to biomass burning and fossil fuel consumption, while they are removed from the atmosphere primarily by OH reaction and by dry deposition. In addition, a branch of aromatics (ortho-nitrophenols) produce HONO upon photolysis, which is responsible of certain amount of the OH recycling. Despite their importance in the atmosphere in anthropogenic polluted areas, the influence of aromatics in the ozone production remains largely unknown. This is of particular relevance, being ozone a pollutant with severe side effects on air quality, health and climate. In this work the atmospheric impacts at global scale of the most emitted aromatic VOCs in the gas phase (benzene, toluene, xylenes, ethylbenzene, styrene, phenol, benzaldehyde and trimethylbenzenes) are analysed and assessed. Specifically, the impact on ozone due to aromatic oxidation is estimated, as this is of great interest in large urban areas and can be helpful for developing air pollution control strategies. Further targets are the quantification of the NOx loss and the OH recycling due to aromatic oxidation. In order to investigate these processes, two simulations were performed with the numerical chemistry and climate simulation ECHAM/MESSy Atmospheric Chemistry (EMAC) model. The simulations compare two cases, one with ozone concentrations when aromatics are present or the second one when they are missing. Finally, model simulated ozone is compared against a global set of observations in order to better constrain the model accuracy.

  14. Production of aromatics from di- and polyoxygenates

    Energy Technology Data Exchange (ETDEWEB)

    Beck, Taylor; Blank, Brian; Jones, Casey; Woods, Elizabeth; Cortright, Randy

    2017-07-04

    Methods, catalysts, and reactor systems for producing in high yield aromatic chemicals and liquid fuels from a mixture of oxygenates comprising di- and polyoxygenates are disclosed. Also disclosed are methods, catalysts, and reactor systems for producing aromatic chemicals and liquid fuels from oxygenated hydrocarbons such as carbohydrates, sugars, sugar alcohols, sugar degradation products, and the like; and methods, catalysts, and reactor systems for producing the mixture of oxygenates from oxygenated hydrocarbons such as carbohydrates, sugars, sugar alcohols, sugar degradation products, and the like. The disclosed catalysts for preparing the mixture of oxygenates comprise a Ni.sub.nSn.sub.m alloy and a crystalline alumina support.

  15. Formic-acid-induced depolymerization of oxidized lignin to aromatics

    Science.gov (United States)

    Rahimi, Alireza; Ulbrich, Arne; Coon, Joshua J.; Stahl, Shannon S.

    2014-11-01

    Lignin is a heterogeneous aromatic biopolymer that accounts for nearly 30% of the organic carbon on Earth and is one of the few renewable sources of aromatic chemicals. As the most recalcitrant of the three components of lignocellulosic biomass (cellulose, hemicellulose and lignin), lignin has been treated as a waste product in the pulp and paper industry, where it is burned to supply energy and recover pulping chemicals in the operation of paper mills. Extraction of higher value from lignin is increasingly recognized as being crucial to the economic viability of integrated biorefineries. Depolymerization is an important starting point for many lignin valorization strategies, because it could generate valuable aromatic chemicals and/or provide a source of low-molecular-mass feedstocks suitable for downstream processing. Commercial precedents show that certain types of lignin (lignosulphonates) may be converted into vanillin and other marketable products, but new technologies are needed to enhance the lignin value chain. The complex, irregular structure of lignin complicates chemical conversion efforts, and known depolymerization methods typically afford ill-defined products in low yields (that is, less than 10-20wt%). Here we describe a method for the depolymerization of oxidized lignin under mild conditions in aqueous formic acid that results in more than 60wt% yield of low-molecular-mass aromatics. We present the discovery of this facile C-O cleavage method, its application to aspen lignin depolymerization, and mechanistic insights into the reaction. The broader implications of these results for lignin conversion and biomass refining are also considered.

  16. Microbial platform for production of aromatic compounds

    DEFF Research Database (Denmark)

    Skovbjerg, Christine Alexandra Egaa; Olsen, Kresten Jon Kromphardt; Larsen, Thomas Ostenfeld

    2017-01-01

    Polyketides form the basic building blocks of numerous natural products, which are in use in pharmaceuticals, food additives and other fine chemicals. Many of these polyketides possess very specific cyclic and aromatic conformations. The programmable platform we aim to create will be able...

  17. Development of a yeast cell factory for production of aromatic products

    DEFF Research Database (Denmark)

    Rodriguez Prado, Edith Angelica; Kildegaard, Kanchana Rueksomtawin; Li, Mingji

    2014-01-01

    There is much interest in aromatic chemicals in the chemical industry as these can be used for production of dyes, anti-oxidants, nutraceuticals and food ingredients. Yeast is a widely used cell factory and it is particularly well suited for production of aromatic chemicals via complex biosynthetic...... routes involving P450 enzymes. In Saccharomyces cerevisiae the fluxes towards aromatic acids (L-tryptophan, L-tyrosine and L-phenylalanine) are strictly controlled on transcriptional and kinetic levels and therefore are difficult to manipulate. We engineered S. cerevisiae for increased production...... of aromatic compounds by eliminating degradation, up-regulating the key enzyme encoding genes, and removing feed-back inhibition in the pathway. In order to test the strain performance we overexpressed heterologous pathway for coumaric acid production. We obtained 4-fold higher concentrations of coumaric acid...

  18. Aromatic plant production on metal contaminated soils

    International Nuclear Information System (INIS)

    Zheljazkov, Valtcho D.; Craker, Lyle E.; Xing Baoshan; Nielsen, Niels E.; Wilcox, Andrew

    2008-01-01

    Field and container experiments were conducted to assess the feasibility of growing aromatic crops in metal contaminated areas and the effect of metals on herbage and oil productivity. The field experiments were conducted in the vicinities of the Non-Ferrous Metals Combine (Zn-Cu smelter) near Plovdiv, Bulgaria using coriander, sage, dill, basil, hyssop, lemon balm, and chamomile grown at various distances from the smelter. Herbage essential oil yields of basil, chamomile, dill, and sage were reduced when they were grown closer to the smelter. Metal removal from the site with the harvestable plant parts was as high as 180 g ha -1 for Cd, 660 g ha -1 for Pb, 180 g ha -1 for Cu, 350 g ha -1 for Mn, and 205 g ha -1 for Zn. Sequential extraction of soil demonstrated that metal fractionation was affected by the distance to the smelter. With decreasing distance to the smelter, the transfer factor (TF) for Cu and Zn decreased but increased for Cd, while the bioavailability factor (BF) for Cd, Pb, Cu, Mn, and Zn decreased. Scanning electron microscopy and X-ray microanalyses of contaminated soil verified that most of the Pb, Cd, Mn, Cu, and Zn were in the form of small (< 1 μm) particles, although there were larger particles (1-5 μm) with high concentrations of individual metals. This study demonstrated that high concentrations of heavy metals in soil or growth medium did not result in metal transfer into the essential oil. Of the tested metals, only Cu at high concentrations may reduce oil content. Our results demonstrated that aromatic crops may not have significant phytoremediation potential, but growth of these crops in metal contaminated agricultural soils is a feasible alternative. Aromatic crops can provide economic return and metal-free final product, the essential oil

  19. Aromatic plant production on metal contaminated soils

    Energy Technology Data Exchange (ETDEWEB)

    Zheljazkov, Valtcho D. [Mississippi State, Department of Plant and Soil Sciences and North Mississippi Research and Extension Center, 5421 Highway 145 South, Verona, MS 38879 (United States)], E-mail: vj40@pss.msstate.edu; Craker, Lyle E.; Xing Baoshan [Department of Plant and Soil Sciences, 12 Stockbridge Hall, University of Massachusetts, Amherst, MA 01003 (United States); Nielsen, Niels E. [Plant Nutrition and Soil Fertility Lab, Department of Agricultural Sciences, Royal Veterinary and Agricultural University, Thorvaldsensvej 40, DK1871, Copenhagen (Denmark); Wilcox, Andrew [Harper Adams University College, Newport, Shropshire, TF10 8NB (United Kingdom)

    2008-06-01

    Field and container experiments were conducted to assess the feasibility of growing aromatic crops in metal contaminated areas and the effect of metals on herbage and oil productivity. The field experiments were conducted in the vicinities of the Non-Ferrous Metals Combine (Zn-Cu smelter) near Plovdiv, Bulgaria using coriander, sage, dill, basil, hyssop, lemon balm, and chamomile grown at various distances from the smelter. Herbage essential oil yields of basil, chamomile, dill, and sage were reduced when they were grown closer to the smelter. Metal removal from the site with the harvestable plant parts was as high as 180 g ha{sup -1} for Cd, 660 g ha{sup -1} for Pb, 180 g ha{sup -1} for Cu, 350 g ha{sup -1} for Mn, and 205 g ha{sup -1} for Zn. Sequential extraction of soil demonstrated that metal fractionation was affected by the distance to the smelter. With decreasing distance to the smelter, the transfer factor (TF) for Cu and Zn decreased but increased for Cd, while the bioavailability factor (BF) for Cd, Pb, Cu, Mn, and Zn decreased. Scanning electron microscopy and X-ray microanalyses of contaminated soil verified that most of the Pb, Cd, Mn, Cu, and Zn were in the form of small (< 1 {mu}m) particles, although there were larger particles (1-5 {mu}m) with high concentrations of individual metals. This study demonstrated that high concentrations of heavy metals in soil or growth medium did not result in metal transfer into the essential oil. Of the tested metals, only Cu at high concentrations may reduce oil content. Our results demonstrated that aromatic crops may not have significant phytoremediation potential, but growth of these crops in metal contaminated agricultural soils is a feasible alternative. Aromatic crops can provide economic return and metal-free final product, the essential oil.

  20. Structure-Activity Relationships for Rates of Aromatic Amine Oxidation by Manganese Dioxide.

    Science.gov (United States)

    Salter-Blanc, Alexandra J; Bylaska, Eric J; Lyon, Molly A; Ness, Stuart C; Tratnyek, Paul G

    2016-05-17

    New energetic compounds are designed to minimize their potential environmental impacts, which includes their transformation and the fate and effects of their transformation products. The nitro groups of energetic compounds are readily reduced to amines, and the resulting aromatic amines are subject to oxidation and coupling reactions. Manganese dioxide (MnO2) is a common environmental oxidant and model system for kinetic studies of aromatic amine oxidation. In this study, a training set of new and previously reported kinetic data for the oxidation of model and energetic-derived aromatic amines was assembled and subjected to correlation analysis against descriptor variables that ranged from general purpose [Hammett σ constants (σ(-)), pKas of the amines, and energies of the highest occupied molecular orbital (EHOMO)] to specific for the likely rate-limiting step [one-electron oxidation potentials (Eox)]. The selection of calculated descriptors (pKa, EHOMO, and Eox) was based on validation with experimental data. All of the correlations gave satisfactory quantitative structure-activity relationships (QSARs), but they improved with the specificity of the descriptor. The scope of correlation analysis was extended beyond MnO2 to include literature data on aromatic amine oxidation by other environmentally relevant oxidants (ozone, chlorine dioxide, and phosphate and carbonate radicals) by correlating relative rate constants (normalized to 4-chloroaniline) to EHOMO (calculated with a modest level of theory).

  1. Structure-Activity Relationships for Rates of Aromatic Amine Oxidation by Manganese Dioxide

    International Nuclear Information System (INIS)

    Salter-Blanc, Alexandra J.; Lyon, Molly A.; Science University, Portland, OR; Ness, Stuart C.; Science University, Portland, OR; Tratnyek, Paul G.; Science University, Portland, OR

    2016-01-01

    New energetic compounds are designed to minimize their potential environmental impacts, which includes their transformation and the fate and effects of their transformation products. The nitro groups of energetic compounds are readily reduced to amines, and the resulting aromatic amines are subject to oxidation and coupling reactions. Manganese dioxide (MnO 2 ) is a common environmental oxidant and model system for kinetic studies of aromatic amine oxidation. Here in this study, a training set of new and previously reported kinetic data for the oxidation of model and energetic-derived aromatic amines was assembled and subjected to correlation analysis against descriptor variables that ranged from general purpose [Hammett σ constants (σ − ), pK a s of the amines, and energies of the highest occupied molecular orbital (E HOMO )] to specific for the likely rate-limiting step [one-electron oxidation potentials (E ox )]. The selection of calculated descriptors (pK a ), E HOMO , and E ox ) was based on validation with experimental data. All of the correlations gave satisfactory quantitative structure-activity relationships (QSARs), but they improved with the specificity of the descriptor. The scope of correlation analysis was extended beyond MnO 2 to include literature data on aromatic amine oxidation by other environmentally relevant oxidants (ozone, chlorine dioxide, and phosphate and carbonate radicals) by correlating relative rate constants (normalized to 4-chloroaniline) to E HOMO (calculated with a modest level of theory).

  2. Synthesis of a Fluorescent Acridone Using a Grignard Addition, Oxidation, and Nucleophilic Aromatic Substitution Reaction Sequence

    Science.gov (United States)

    Goodrich, Samuel; Patel, Miloni; Woydziak, Zachary R.

    2015-01-01

    A three-pot synthesis oriented for an undergraduate organic chemistry laboratory was developed to construct a fluorescent acridone molecule. This laboratory experiment utilizes Grignard addition to an aldehyde, alcohol oxidation, and iterative nucleophilic aromatic substitution steps to produce the final product. Each of the intermediates and the…

  3. 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

  4. Oxidation kinetics of polycyclic aromatic hydrocarbons by permanganate

    Energy Technology Data Exchange (ETDEWEB)

    Forsey, S.P.; Thomson, N.R.; Barker, J.F. [University of Waterloo, Waterloo, ON (Canada). Dept. of Civil & Environmental Engineering

    2010-04-15

    The reactivity of permanganate towards polycyclic aromatics hydrocarbons (PAHs) is well known but little kinetic information is available. This study investigated the oxidation kinetics of a selected group of coal tar creosote compounds and alkylbenzenes in water using permanganate, and the correlation between compound reactivity and physical/chemical properties. The oxidation of naphthalene, phenanthrene, chrysene, 1-methylnaphthalene, 2-methylnaphthalene, acenaphthene, fluorene, carbazole isopropylbenzene, ethylbenzene and methylbenzene closely followed pseudo first-order reaction kinetics. The oxidation of pyrene was initially very rapid and did not follow pseudo first-order kinetics at early times. Fluoranthene was only partially oxidized and the oxidation of anthracene was too fast to be captured. Biphenyl, dibenzofuran, benzene and tert-butylbenzene were non-reactive under the study conditions. The oxidation rate was shown to increase with increasing number of polycyclic rings because less energy is required to overcome the aromatic character of a polycyclic ring than is required for benzene. Thus the rate of oxidation increased in the series naphthalene < phenanthrene < pyrene. The rate of side chain reactivity is controlled by the C-H bond strength. For the alkyl substituted benzenes an excellent correlation was observed between the reaction rate coefficients and bond dissociation energies, but for the substituted PAHs the relationship was poor. A trend was found between the reaction rate coefficients and the calculated heats of complexation indicating that significant ring oxidation occurred in addition to side chain oxidation. Clar's aromatic sextet theory was used to predict the relative stability of arenes towards ring oxidation by permanganate.

  5. Recent Advances in Microbial Production of Aromatic Chemicals and Derivatives.

    Science.gov (United States)

    Noda, Shuhei; Kondo, Akihiko

    2017-08-01

    Along with the development of metabolic engineering and synthetic biology tools, various microbes are being used to produce aromatic chemicals. In microbes, aromatics are mainly produced via a common important precursor, chorismate, in the shikimate pathway. Natural or non-natural aromatics have been produced by engineering metabolic pathways involving chorismate. In the past decade, novel approaches have appeared to produce various aromatics or to increase their productivity, whereas previously, the targets were mainly aromatic amino acids and the strategy was deregulating feedback inhibition. In this review, we summarize recent studies of microbial production of aromatics based on metabolic engineering approaches. In addition, future perspectives and challenges in this research area are discussed. Copyright © 2017 Elsevier Ltd. All rights reserved.

  6. UV irradiation of polycyclic aromatic hydrocarbons in ices: production of alcohols, quinones, and ethers

    Science.gov (United States)

    Bernstein, M. P.; Sandford, S. A.; Allamandola, L. J.; Gillette, J. S.; Clemett, S. J.; Zare, R. N.

    1999-01-01

    Polycyclic aromatic hydrocarbons (PAHs) in water ice were exposed to ultraviolet (UV) radiation under astrophysical conditions, and the products were analyzed by infrared spectroscopy and mass spectrometry. Peripheral carbon atoms were oxidized, producing aromatic alcohols, ketones, and ethers, and reduced, producing partially hydrogenated aromatic hydrocarbons, molecules that account for the interstellar 3.4-micrometer emission feature. These classes of compounds are all present in carbonaceous meteorites. Hydrogen and deuterium atoms exchange readily between the PAHs and the ice, which may explain the deuterium enrichments found in certain meteoritic molecules. This work has important implications for extraterrestrial organics in biogenesis.

  7. Oxidation kinetics of polycyclic aromatic hydrocarbons by permanganate.

    Science.gov (United States)

    Forsey, Steven P; Thomson, Neil R; Barker, James F

    2010-04-01

    The reactivity of permanganate towards polycyclic aromatics hydrocarbons (PAHs) is well known but little kinetic information is available. This study investigated the oxidation kinetics of a selected group of coal tar creosote compounds and alkylbenzenes in water using permanganate, and the correlation between compound reactivity and physical/chemical properties. The oxidation of naphthalene, phenanthrene, chrysene, 1-methylnaphthalene, 2-methylnaphthalene, acenaphthene, fluorene, carbazole isopropylbenzene, ethylbenzene and methylbenzene closely followed pseudo first-order reaction kinetics. The oxidation of pyrene was initially very rapid and did not follow pseudo first-order kinetics at early times. Fluoranthene was only partially oxidized and the oxidation of anthracene was too fast to be captured. Biphenyl, dibenzofuran, benzene and tert-butylbenzene were non-reactive under the study conditions. The oxidation rate was shown to increase with increasing number of polycyclic rings because less energy is required to overcome the aromatic character of a polycyclic ring than is required for benzene. Thus the rate of oxidation increased in the series naphthalenepermanganate. 2010 Elsevier Ltd. All rights reserved.

  8. A method of refining aromatic hydrocarbons from coal chemical production

    Energy Technology Data Exchange (ETDEWEB)

    Zieborak, K.; Koprowski, A.; Ratajczak, W.

    1979-10-01

    A method is disclosed for refining aromatic hydrocarbons of coal chemical production by contact of liquid aromatic hydrocarbons and their mixtures with a strongly acid macroporous sulfocationite in the H-form at atmospheric pressure and high temperature. The method is distinguished in that the aromatic hydrocarbons and their mixtures, from which alkali compounds have already been removed, are supplied for refinement with the sulfocationite with simultaneous addition of olefin derivatives of aromatic hydrocarbons, followed by separation of pure hydrocarbons by rectification. Styrene or alpha-methylstyrene is used as the olefin derivatives of the aromatic hydrocarbons. The method is performed in several stages with addition of olefin derivatives of aromatic hydrocarbons at each stage.

  9. Adsorption of polar, nonpolar, and substituted aromatics to colloidal graphene oxide nanoparticles

    NARCIS (Netherlands)

    Wang, Fang; Haftka, Joris J H; Sinnige, Theo L.; Hermens, Joop L M; Chen, Wei

    2014-01-01

    We conducted batch adsorption experiments to understand the adsorptive properties of colloidal graphene oxide nanoparticles (GONPs) for a range of environmentally relevant aromatics and substituted aromatics, including model nonpolar compounds (pyrene, phenanthrene, naphthalene, and

  10. Interaction of oxides of nitrogen and aromatic hydrocarbons under simulated atmospheric conditions

    International Nuclear Information System (INIS)

    Obrien, R.J.; Green, P.J.; Doty, R.A.; Vanderzanden, J.W.; Easton, R.R.; Irwin, R.P.

    1979-01-01

    The reactions of nitrogen oxides with aromatic hydrocarbons under simulated atmospheric conditions are investigated. Gaseous reaction products formed when toluene is irradiated under simulated atmospheric conditions in the presence of nitrogen oxides were analyzed by gas chromatography. Reaction products detected include acetylene, water, acetaldehyde, acetone, toluene, benzaldehyde, ortho-, meta- and para-cresol, benzyl nitrate and meta- and para-nitrotoluene. Reaction mechanisms yielding the various products are illustrated. The assumption that all the nitrogen oxides observed to be lost from the reaction products can be accounted for by nitric acid formation in the absence of ozone formation is verified by a model in which the hydroxyl radical is assumed to be the only means of removing toluene. Under conditions in which ozone is formed, nitrogen oxide loss is accounted for by ozone formation in addition to nitric acid formation

  11. Radiation deterioration of several aromatic polymers under oxidative conditions

    International Nuclear Information System (INIS)

    Sasuga, Tsuneo; Hagiwara, Miyuki

    1987-01-01

    Radiation-induced oxidative irradiation effects (with γ-rays under oxygen pressure) or poly(aryl sulphones) (U-PS and PES), poly(aryl ester) (U-Polymer), poly(aryl amide) (A-Film) and poly(aryl ether ether ketone) (PEEK) have been studied based on changes in tensile properties. The deterioration dose estimated from the decrease in the elongation at break was as low as one-fifth to one-tenth of that in high-dose-rate electron-beam irradiation, but the order of radiation resistance of the polymers did not differ from that in electron-beam irradiation, i.e. PEEK > A-Film > U-Polymer > U-PS > PES. The radiation stability of aromatic units under oxidative conditions was estimated from a comparison of the radiation resistance of the polymers themselves and their chemical structures. The following order was obtained: diphenyl ether, diphenyl ketone > aromatic amide>> bisphenol A > diphenyl sulphone. The deterioration mechanism of PEEK under oxidative irradiation was studied by measuring dynamic viscoelastic properties. It was concluded that deterioration in mechanical properties under oxidative irradiation was brought about by chain scission only. (author)

  12. Equilibrium studies of the adsorption of aromatic disulfonates by Mg-Al oxide

    Science.gov (United States)

    Kameda, Tomohito; Umetsu, Mami; Kumagai, Shogo; Yoshioka, Toshiaki

    2018-03-01

    The removal of m-benzenedisulfonate (BDS2-) and 2,6-naphthalenedisulfonate (NDS2-) anions by Mg-Al oxide was investigated. Langmuir model best describes the adsorption of both aromatic disulfonate anions, with the maximum amount of uptake higher for BDS2-. Mg-Al oxide reacts easier with the aromatic disulfonate anion with higher charge density, a trend that is the opposite of that observed in aromatic sulfonate anions. After increasing the charge from -1 to -2, the removal of aromatic disulfonates by Mg-Al oxide is controlled by electrostatic interactions, instead of hydrophobic interactions that are dominant for aromatic sulfonate anions.

  13. Palladium-Catalyzed Tandem Oxidative Arylation/Olefination of Aromatic Tethered Alkenes/Alkynes.

    Science.gov (United States)

    Gao, Yang; Gao, Yinglan; Wu, Wanqing; Jiang, Huanfeng; Yang, Xiaobo; Liu, Wenbo; Li, Chao-Jun

    2017-01-18

    We describe herein a palladium-catalyzed tandem oxidative arylation/olefination reaction of aromatic tethered alkenes/alkynes for the synthesis of dihydrobenzofurans and 2 H-chromene derivatives. This reaction features a 1,2-difunctionalization of C-C π-bond with two C-H bonds using O 2 as terminal oxidant at room temperature. The products obtained are valuable synthons and important scaffolds in biological agents and natural products. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  14. Interaction of aromatic amines with iron oxides: implications for prebiotic chemistry.

    Science.gov (United States)

    Shanker, Uma; Singh, Gurinder; Kamaluddin

    2013-06-01

    The interaction of aromatic amines (aniline, p-chloroaniline, p-toludine and p-anisidine) with iron oxides (goethite, akaganeite and hematite) has been studied. Maximum uptake of amines was observed around pH 7. The adsorption data obtained at neutral pH were found to follow Langmuir adsorption. Anisidine was found to be a better adsorbate probably due to its higher basicity. In alkaline medium (pH > 8), amines reacted on goethite and akaganeite to give colored products. Analysis of the products by GC-MS showed benzoquinone and azobenzene as the reaction products of aniline while p-anisidine afforded a dimer. IR analysis of the amine-iron oxide hydroxide adduct suggests that the surface acidity of iron oxide hydroxides is responsible for the interaction. The present study suggests that iron oxide hydroxides might have played a role in the stabilization of organic molecules through their surface activity and in prebiotic condensation reactions.

  15. Catalytic oxidation of 2-aminophenols and ortho hydroxylation of aromatic amines by tyrosinase

    International Nuclear Information System (INIS)

    Toussaint, O.; Lerch, K.

    1987-01-01

    The usual substrates of tyrosinase, a copper-containing monooxygenase (EC 1.14.18.1), are monophenols and o-diphenols which are both converted to o-quinones. In this paper, the authors studied the reaction of this enzyme with two new classes of substrates: aromatic amines and o-aminophenols, structural analogues of monophenols and o-diphenols, respectively. They undergo the same catalytic reactions (ortho hydroxylation and oxidation), as documented by product analysis and kinetic studies. In the presence of tyrosinase, arylamines and o-aminophenols are converted to o-quinone imines, which are isolated as quinone anils or phenoxazones. As an example, in the presence of tyrosinase, 2-amino-3-hydroxybenzoic acid (an o-aminophenol) is converted to cinnabarinic acid, a well-known phenoxazone, while p-aminotoluene (an aromatic amine) gives rise to the formation of 5-amino-2-methyl-1,4-benzoquinone 1-(4-methylanil). Kinetic studies using an oxygen electrode show that arylamines and the corresponding monophenols exhibit similar Michaelis constants. In contrast, the reaction rates observed for aromatic amines are relatively slow as compared to monophenols. The enzymatic conversion of arylamines by tryosinase is different from the typical ones: N-oxidation and ring hydroxylation without further oxidation. This difference originates from the regiospecific hydroxylation (ortho position) and subsequent oxidation of the intermediate o-aminophenol to the corresponding o-quinone imine. Finally, the well-know monooxygenase activity of tyrosinase was also confirmed for the aromatic amine p-aminotoluene, with 18 O 2

  16. Manufacture of aromatic hydrocarbons from coal hydrogenation products

    Energy Technology Data Exchange (ETDEWEB)

    A.S. Maloletnev; M.A. Gyul' malieva [Institute for Fossil Fuels, Moscow (Russian Federation)

    2007-08-15

    The manufacture of aromatic hydrocarbons from coal distillates was experimentally studied. A flow chart for the production of benzene, ethylbenzene, toluene, and xylenes was designed, which comprised the hydrogen treatment of the total wide-cut (or preliminarily dephenolized) fraction with FBP 425{sup o}C; fractional distillation of the hydrotreated products into IBP-60, 60-180, 180-300, and 300-425{sup o}C fractions; the hydro-cracking of middle fractions for increasing the yield of gasoline fractions whenever necessary; the catalytic reform of the fractions with bp up to 180{sup o}C; and the extraction of aromatic hydrocarbons.

  17. Metallo-deuteroporphyrin as a biomimetic catalyst for the catalytic oxidation of lignin to aromatics.

    Science.gov (United States)

    Zhu, Chenjie; Ding, Weiwei; Shen, Tao; Tang, Chenglun; Sun, Chenguo; Xu, Shichao; Chen, Yong; Wu, Jinglan; Ying, Hanjie

    2015-05-22

    A series of metallo-deuteroporphyrins derived from hemin were prepared as models of the cytochrome P450 enzyme. With the aid of the highly active Co(II) deuteroporphyrin complex, the catalytic oxidation system was applied for the oxidation of several lignin model compounds, and high yields of monomeric products were obtained under mild reaction conditions. It was found that the modified cobalt deuteroporphyrin that has no substituents at the meso sites but does have the disulfide linkage in the propionate side chains at the β sites exhibited much higher activity and stability than the synthetic tetraphenylporphyrin. The changes in the propionate side chains can divert the reactivity of cobalt deuteroporphyrins from the typical CC bond cleavage to CO bond cleavage. Furthermore, this novel oxidative system can convert enzymolysis lignin into depolymerized products including a significant portion of well-defined aromatic monomers. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  18. Metal Triflates for the Production of Aromatics from Lignin.

    Science.gov (United States)

    Deuss, Peter J; Lahive, Ciaran W; Lancefield, Christopher S; Westwood, Nicholas J; Kamer, Paul C J; Barta, Katalin; de Vries, Johannes G

    2016-10-20

    The depolymerization of lignin into valuable aromatic chemicals is one of the key goals towards establishing economically viable biorefineries. In this contribution we present a simple approach for converting lignin to aromatic monomers in high yields under mild reaction conditions. The methodology relies on the use of catalytic amounts of easy-to-handle metal triflates (M(OTf) x ). Initially, we evaluated the reactivity of a broad range of metal triflates using simple lignin model compounds. More advanced lignin model compounds were also used to study the reactivity of different lignin linkages. The product aromatic monomers were either phenolic C2-acetals obtained by stabilization of the aldehyde cleavage products by reaction with ethylene glycol or methyl aromatics obtained by catalytic decarbonylation. Notably, when the method was ultimately tested on lignin, especially Fe(OTf) 3 proved very effective and the phenolic C2-acetal products were obtained in an excellent, 19.3±3.2 wt % yield. © 2016 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  19. Photocatalytic oxidation of aromatic amines using MnO2@g-C3N4

    Data.gov (United States)

    U.S. Environmental Protection Agency — An efficient and direct oxidation of aromatic amines to aromatic azo-compounds has been achieved using a MnO2@g-C3N4 catalyst under visible light as a source of...

  20. Photocatalytic oxidation of aromatic amines using MnO2@g ...

    Science.gov (United States)

    An efficient and direct oxidation of aromatic amines to aromatic azo-compounds has been achieved using a MnO2@g-C3N4 catalyst under visible light as a source of energy at room temperature Prepared for submission to the journal, Advanced Materials Letters.

  1. Ensemble modeling for aromatic production in Escherichia coli.

    Directory of Open Access Journals (Sweden)

    Matthew L Rizk

    2009-09-01

    Full Text Available Ensemble Modeling (EM is a recently developed method for metabolic modeling, particularly for utilizing the effect of enzyme tuning data on the production of a specific compound to refine the model. This approach is used here to investigate the production of aromatic products in Escherichia coli. Instead of using dynamic metabolite data to fit a model, the EM approach uses phenotypic data (effects of enzyme overexpression or knockouts on the steady state production rate to screen possible models. These data are routinely generated during strain design. An ensemble of models is constructed that all reach the same steady state and are based on the same mechanistic framework at the elementary reaction level. The behavior of the models spans the kinetics allowable by thermodynamics. Then by using existing data from the literature for the overexpression of genes coding for transketolase (Tkt, transaldolase (Tal, and phosphoenolpyruvate synthase (Pps to screen the ensemble, we arrive at a set of models that properly describes the known enzyme overexpression phenotypes. This subset of models becomes more predictive as additional data are used to refine the models. The final ensemble of models demonstrates the characteristic of the cell that Tkt is the first rate controlling step, and correctly predicts that only after Tkt is overexpressed does an increase in Pps increase the production rate of aromatics. This work demonstrates that EM is able to capture the result of enzyme overexpression on aromatic producing bacteria by successfully utilizing routinely generated enzyme tuning data to guide model learning.

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

    Directory of Open Access Journals (Sweden)

    C. Bloss

    2005-01-01

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

  3. Synthesis of Heteroaromatic Compounds by Oxidative Aromatization Using an Activated Carbon/Molecular Oxygen System

    Directory of Open Access Journals (Sweden)

    Masahiko Hayashi

    2009-08-01

    Full Text Available A variety of heteroaromatic compounds, such as substituted pyridines, pyrazoles, indoles, 2-substituted imidazoles, 2-substituted imidazoles, 2-arylbenzazoles and pyrimidin-2(1H-ones are synthesized by oxidative aromatization using the activated carbon and molecular oxygen system. Mechanistic study focused on the role of activated carbon in the synthesis of 2-arylbenzazoles is also discussed. In the final section, we will disclose the efficient synthesis of substituted 9,10-anthracenes via oxidative aromatization.

  4. Development of a yeast cell factory for production of aromatic secondary metabolites

    DEFF Research Database (Denmark)

    Rodriguez Prado, Edith Angelica

    Aromatic secondary metabolites are compounds mainly synthesized by plants and fungi as a response to predators and environmental stresses. These compounds have a broad range of natural properties such as reduction of oxidative damage in cells, antibacterial effects and UV protection. Many...... of these properties can be useful for the treatment of different diseases and development of pharmaceutical products. The low abundance of these compounds in natural sources together with technical challenges for the extraction of these compounds from plants, open up the possibility for synthesizing aromatic....... The systems biology analysis of the platform strain suggests that the strain has transcriptional downregulations in genes involved in the transport of amino acids and sugars, which could be a response to the stress triggered by the production of p-coumaric acid. The platform strain was capable of synthesizing...

  5. Pseudopterosin Biosynthesis: Aromatization of the Diterpene Cyclase Product, Elisabethatriene

    Directory of Open Access Journals (Sweden)

    Amber C. Kohl

    2003-11-01

    Full Text Available Abstract: Putative precursors in pseudopterosin biosynthesis, the hydrocarbons isoelisabethatriene (10 and erogorgiaene (11, have been identified from an extract of Pseudopterogorgia elisabethae collected in the Florida Keys. Biosynthetic experiments designed to test the utilization of these compounds in pseudopterosin production revealed that erogorgiaene is transformed to pseudopterosins A-D. Together with our previous data, it is now apparent that early steps in pseudopterosin biosynthesis involve the cyclization of geranylgeranyl diphosphate to elisabethatriene followed by the dehydrogenation and aromatization to erogorgiaene.

  6. Green chemistry perspectives of methane conversion via oxidative methylation of aromatics over zeolite catalysts

    Energy Technology Data Exchange (ETDEWEB)

    Adebajo, M.O. [University of Queensland, St Lucia, Qld. (Australia)

    2007-06-15

    This paper provides a general overview of the recent work that we and other researchers have done on the utilisation of methane for catalytic methylation of aromatic compounds and for direct coal liquefaction for the production of liquid hydrocarbons. In particular, the paper presents a detailed description of more recent substantial experimental evidence that we have provided for the requirement of oxygen as a stoichiometry reactant for benzene methylation with methane over moderately acidic zeolite catalysts. The reaction, which has been termed 'oxidative methylation', was thus postulated to involve a two-step mechanism involving intermediate methanol formation by methane partial oxidation, followed by benzene methylation with methanol in the second step. However, strongly acidic zeolites can cause cracking of benzene to yield methylated products in the absence of oxygen. The participation of methane and oxygen, and the effective use of zeolite catalysts in this methylation reaction definitely have some positive green chemistry implications. Thus, the results of these previous studies are also discussed in this review in light of the principles and tools of green chemistry. Various metrics were used to evaluate the greenness, cost-effectiveness, and material and energy efficiency of the oxidative methylation reaction.

  7. Nitroxyl-mediated oxidation of lignin and polycarboxylated products

    Energy Technology Data Exchange (ETDEWEB)

    Stahl, Shannon S.; Rafiee, Mohammad

    2018-02-27

    Methods of selectively modifying lignin, polycarboxylated products thereof, and methods of deriving aromatic compounds therefrom. The methods comprise electrochemically oxidizing lignin using stable nitroxyl radicals to selectively oxidize primary hydroxyls on .beta.-O-4 phenylpropanoid units to corresponding carboxylic acids while leaving the secondary hydroxyls unchanged. The oxidation results in polycarboxylated lignin in the form of a polymeric .beta.-hydroxy acid. The polymeric .beta.-hydroxy acid has a high loading of carboxylic acid and can be isolated in acid form, deprotonated, and/or converted to a salt. The .beta.-hydroxy acid, anion, or salt can also be subjected to acidolysis to generate various aromatic monomers or oligomers. The initial oxidation of lignin to the polycarboxylated form renders the lignin more susceptible to acidolysis and thereby enhances the yield of aromatic monomers and oligomers obtained through acidolysis.

  8. Study of interaction and adsorption of aromatic amines by manganese oxides and their role in chemical evolution

    Science.gov (United States)

    Bhushan, Brij; Nayak, Arunima; Kamaluddin

    2017-04-01

    The role of manganese oxides in concentrating organic moieties and offering catalytic activity for prebiotic reactions is investigated by studying their interaction with different aromatic amines such as aniline, p-chloroaniline, p-toluidine and p-anisidine. For all amines, metal oxides showed highest adsorption at neutral pH. The order of their adsorption capacity and affinity as revealed by the Langmuir constants was found to be manganosite (MnO) > bixbyite (Mn2O3) > hausmannite (Mn3O4) > and pyrolusite (MnO2). At alkaline pH, these manganese oxides offered their surfaces for oxidation of amines to form coloured oligomers. Analysis of the oxidation products by gas chromatography-mass spectrometry showed the formation of a dimer from p-anisidine and p-chloroaniline, while a trimer and tetramer is formed from p-toluidine and aniline, respectively. A reaction mechanism is proposed for the formation of the oligomers. While field-emission scanning electron microscopic studies confirm the binding phenomenon, the Fourier transform infrared spectroscopy analysis suggests that the mechanism of binding of amines on the manganese oxides was primarily electrostatic. The adsorption behaviour of the studied aromatic amines followed the order: p-anisidine > p-toluidine > aniline > p-chloroaniline, which is related to the basicities and structure of the amines. Our studies confirmed the significance of the role of manganese oxides in prebiotic chemistry.

  9. Microwave-Accelerated Iodination of Some Aromatic Amines, Using Urea-Hydrogen Peroxide Addition Compound (UHP as the Oxidant

    Directory of Open Access Journals (Sweden)

    Lech Skulski

    2002-12-01

    Full Text Available A fast and simple method for the oxidative iodination of some aromatic amines, under microwave irradiation, is reported, using diiodine and the the strongly Hbonded urea-hydrogen peroxide addition compound (H2NCONH2···H2O2, UHP as the oxidant. The reactions were carried out in boiling CHCl3 under a reflux condenser to afford, within 10 minutes, the purified monoiodinated products in 40-80% yields.

  10. Magnetic graphene oxide as adsorbent for the determination of polycyclic aromatic hydrocarbon metabolites in human urine.

    Science.gov (United States)

    Zhu, Linli; Xu, Hui

    2014-09-01

    Detection of monohydroxy polycyclic aromatic hydrocarbons metabolites in urine is an advisable and valid method to assess human environmental exposure to polycyclic aromatic hydrocarbons. In this work, novel Fe3O4/graphene oxide composites were prepared and their application in the magnetic solid-phase extraction of monohydroxy polycyclic aromatic hydrocarbons in urine was investigated by coupling with liquid chromatography and mass spectrometry. In the hybrid material, superparamagnetic Fe3O4 nanoparticles provide fast separation to simplify the analytical process and graphene oxide provides a large functional surface for the adsorption. The prepared magnetic nanocomposites were characterized by X-ray diffraction, scanning electron microscopy, transmission electron microscopy, and vibrating sample magnetometry. The experimental conditions were optimized systematically. Under the optimal conditions, the recoveries of these compounds were in the range of 98.3-125.2%, the relative standard deviations ranged between 6.8 and 15.5%, and the limits of detection were in the range of 0.01-0.15 ng/mL. The simple, quick, and affordable method was successfully used in the analysis of human urinary monohydroxy polycyclic aromatic hydrocarbons in two different cities. The results indicated that the monohydroxy polycyclic aromatic hydrocarbons level in human urine can provide useful information for environmental exposure to polycyclic aromatic hydrocarbons. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  11. Oxidation of aromatic alcohols on zeolite-encapsulated copper amino acid complexes

    Energy Technology Data Exchange (ETDEWEB)

    Ernst, S.; Teixeira Florencio, J.M. [Kaiserslautern Univ. (Germany). Dept. of Chemistry, Chemical Technology

    1998-12-31

    Copper complexes of the amino acids histidine, arginine and lysine have been introduced into the supercages of zeolite Y and, for the first time, into the large intracrystalline cavities of zeolites EMT and MCM-22. The resulting host/guest compounds are characterized by X-ray powder diffraction, UV/VIS-spectroscopy in the diffuse reflectance mode and by catalytic tests in the liquid-phase oxidation of aromatic alcohols (viz. benzyl alcohol, 2- and 3-methylbenzyl alcohol and 2,5-dimethylbenzyl alcohol) with tertiary-butylhydroperoxide as oxidant. It was observed that intracrystalline copper-amino acid complexes possess remarkable catalytic activity, yielding the corresponding aromatic aldehydes and acids. (orig.)

  12. Adsorption of polycyclic aromatic hydrocarbons on graphene oxides and reduced graphene oxides.

    Science.gov (United States)

    Sun, Yubing; Yang, Shubin; Zhao, Guixia; Wang, Qi; Wang, Xiangke

    2013-11-01

    Graphene has attracted increasing attention in multidisciplinary studies because of its unique physical and chemical properties. Herein, the adsorption of polycyclic aromatic hydrocarbons (PAHs), such as naphthalene (NAP), anthracene (ANT), and pyrene (PYR), on reduced graphene oxides (rGOs) and graphene oxides (GOs) as a function of pH, humic acid (HA), and temperature were elucidated by means of a batch technique. For comparison, nonpolar and nonporous graphite were also employed in this study. The increasing of pH from 2 to 11 did not influence the adsorption of PAHs on rGOs, whereas the suppressed adsorption of NAP on rGOs was observed both in the presence of HA and under high-temperature conditions. Adsorption isotherms of PAHs on rGOs were in accordance with the Polanyi-Dubinin-Ashtahhov (PDA) model, providing evidence that pore filling and flat surface adsorption were involved. The saturated adsorbed capacities (in mmol g(-1)) of rGOs for PAHs calculated from the PDA model significantly decreased in the order of NAP>PYR>ANT, which was comparable to the results of theoretical calculations. The pore-filling mechanism dominates the adsorption of NAP on rGOs, but the adsorption mechanisms of ANT and PYR on rGOs are flat surface adsorption. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  13. Relationship between chemical composition and oxidative potential of secondary organic aerosol from polycyclic aromatic hydrocarbons

    Science.gov (United States)

    Wang, Shunyao; Ye, Jianhuai; Soong, Ronald; Wu, Bing; Yu, Legeng; Simpson, André J.; Chan, Arthur W. H.

    2018-03-01

    Owing to the complex nature and dynamic behaviors of secondary organic aerosol (SOA), its ability to cause oxidative stress (known as oxidative potential, or OP) and adverse health outcomes remains poorly understood. In this work, we probed the linkages between the chemical composition of SOA and its OP, and investigated impacts from various SOA evolution pathways, including atmospheric oligomerization, heterogeneous oxidation, and mixing with metal. SOA formed from photooxidation of the two most common polycyclic aromatic hydrocarbons (naphthalene and phenanthrene) were studied as model systems. OP was evaluated using the dithiothreitol (DTT) assay. The oligomer-rich fraction separated by liquid chromatography dominates DTT activity in both SOA systems (52 ± 10 % for naphthalene SOA (NSOA), and 56 ± 5 % for phenanthrene SOA (PSOA)). Heterogeneous ozonolysis of NSOA was found to enhance its OP, which is consistent with the trend observed in selected individual oxidation products. DTT activities from redox-active organic compounds and metals were found to be not additive. When mixing with highly redox-active metal (Cu), OP of the mixture decreased significantly for 1,2-naphthoquinone (42 ± 7 %), 2,3-dihydroxynaphthalene (35 ± 1 %), NSOA (50 ± 6 %), and PSOA (43 ± 4 %). Evidence from proton nuclear magnetic resonance (1H NMR) spectroscopy illustrates that such OP reduction upon mixing can be ascribed to metal-organic binding interactions. Our results highlight the role of aerosol chemical composition under atmospheric aging processes in determining the OP of SOA, which is needed for more accurate and explicit prediction of the toxicological impacts from particulate matter.

  14. Metal Triflates for the Production of Aromatics from Lignin

    NARCIS (Netherlands)

    Deuss, Peter J.; Lahive, Ciaran W.; Lancefield, Christopher S.; Westwood, Nicholas J.; Kamer, Paul C. J.; Barta, Katalin; de Vries, Johannes G.

    2016-01-01

    The depolymerization of lignin into valuable aromatic chemicals is one of the key goals towards establishing economically viable biorefineries. In this contribution we present a simple approach for converting lignin to aromatic monomers in high yields under mild reaction conditions. The methodology

  15. [Comparison of polycyclic aromatic hydrocarbons (PAHS) contents in bakery products].

    Science.gov (United States)

    Ciemniak, Artur; Witczak, Agata

    2010-01-01

    Polycyclic aromatic hydrocarbons are a group of well-known chemical carcinogens with a wide distribution in the environment and formed by the incomplete combustion of organic substances. PAHs have attracted most attention because of their carcinogenic potential. PAHs have been found as contaminants in different food categories such as dairy products, smoked and barbecued meat, vegetables, fruits, oils, coffee, tea, and cereals. Processing of food at high temperatures increases the amount of PAHs in the food Diet is the major source of human exposure to PAHs. The major dietary source of PAH are oils and fats, cereals products and vegetables. The aims of this study were to determine the content levels of 23 PAHs in various sorts of bread. The analytical procedure was based Soxhlet extraction with n--hexane and cleaned up in aflorisil cartridge. Chromatographic separation was performed using gas chromatography (HP 6890) coupled to mass spectrometry (HP 5973). The total concentration of PAHs was low end varied between 2.61 microg/kg to 43.4 microg/kg. Furthermore, the results revealed differences in concentrations of PAHs between rind and bread-crumb.

  16. Reactivity Of Radiolytically-Produced Nitrogen Oxide Radicals Toward Aromatic Compounds

    International Nuclear Information System (INIS)

    Elias, Gracy

    2010-01-01

    The nitration of aromatic compounds in the gas phase is an important source of toxic, carcinogenic, and mutagenic species in the atmosphere and has therefore received much attention. Gas phase nitration typically occurs by free-radical reactions. Condensed-phase free-radical reactions, and in particular nitrite and nitrate radical chemistry, have been studied far less. These condensed-phase free-radical reactions may be relevant in fog and cloud water in polluted areas, in urban aerosols with low pH, in water treatment using advanced oxidation processes such as electron beam (e-beam) irradiation, and in nuclear waste treatment applications. This study discusses research toward an improved understanding of nitration of aromatic compounds in the condensed phase under conditions conducive to free-radical formation. The results are of benefit in several areas of environmental chemistry, in particular nuclear waste treatment applications. The nitration reactions of anisole and toluene as model compounds were investigated in γ-irradiated acidic nitrate, neutral nitrate, and neutral nitrite solutions. Cs-7SB, 1-(2,2,3,3,-tetrafluoropropoxy)-3-(4-sec-butylphenoxy)-2-propanol, is used as a solvent modifier in the fission product extraction (FPEX) formulation for the extraction of Cs and Sr from dissolved nuclear fuel. The formulation also contains the ligands calix(4)arene-bis-(tert-octylbenzo-crown-6) (BOBCalixC6) for Cs extraction and 4,4(prime),(5(prime))-di-(t-butyldicyclohexano)-18-crown-6 (DtBuCH18C6) for Sr extraction, all in Isopar L, a branched-chain alkane diluent. FPEX solvent has favorable extraction efficiency for Cs and Sr from acidic solution and was investigated at the Idaho National Laboratory (INL) for changes in extraction efficiency after γ-irradiation. Extraction efficiency decreased after irradiation. The decrease in solvent extraction efficiency was identical for Cs and Sr, even though they are complexed by different ligands. This suggests that

  17. Aromatic products from reaction of lignin model compounds with UV-alkaline peroxide

    International Nuclear Information System (INIS)

    Sun, Y.P.; Wallis, A.F.A.; Nguyen, K.L.

    1997-01-01

    A series of guaiacyl and syringyl lignin model compounds and their methylated analogues were reacted with alkaline hydrogen peroxide while irradiating with UV light at 254 nm. The aromatic products obtained were investigated by gas chromatography-mass spectrometry (GC-MS). Guaiacol, syringol and veratrol gave no detectable aromatic products. However, syringol methyl ether gave small amounts of aromatic products, resulting from ring substitution and methoxyl displacement by hydroxyl radicals. Reaction of vanillin and syringaldehyde gave the Dakin reaction products, methoxy-1,4-hydroquinones, while reaction of their methyl ethers yielded benzoic acids. Acetoguaiacone, acetosyringone and their methyl ethers afforded several hydroxylated aromatic products, but no aromatic products were identified in the reaction mixtures from guaiacylpropane and syringylpropane. In contrast, veratrylpropane gave a mixture from which 17 aromatic hydroxylated compounds were identified. It is concluded that for phenolic lignin model compounds, particularly those possessing electrondonating aromatic ring substituents, ring-cleavage reactions involving superoxide radical anions are dominant, whereas for non-phenolic lignin models, hydroxylation reactions through attack of hydroxyl radicals prevail

  18. Catalytic Oxidation of Lignins into the Aromatic Aldehydes: General Process Trends and Development Prospects

    Directory of Open Access Journals (Sweden)

    Valery E. Tarabanko

    2017-11-01

    Full Text Available This review discusses principal patterns that govern the processes of lignins’ catalytic oxidation into vanillin (3-methoxy-4-hydroxybenzaldehyde and syringaldehyde (3,5-dimethoxy-4-hydroxybenzaldehyde. It examines the influence of lignin and oxidant nature, temperature, mass transfer, and of other factors on the yield of the aldehydes and the process selectivity. The review reveals that properly organized processes of catalytic oxidation of various lignins are only insignificantly (10–15% inferior to oxidation by nitrobenzene in terms of yield and selectivity in vanillin and syringaldehyde. Very high consumption of oxygen (and consequentially, of alkali in the process—over 10 mol per mol of obtained vanillin—is highlighted as an unresolved and unexplored problem: scientific literature reveals almost no studies devoted to the possibilities of decreasing the consumption of oxygen and alkali. Different hypotheses about the mechanism of lignin oxidation into the aromatic aldehydes are discussed, and the mechanism comprising the steps of single-electron oxidation of phenolate anions, and ending with retroaldol reaction of a substituted coniferyl aldehyde was pointed out as the most convincing one. The possibility and development prospects of single-stage oxidative processing of wood into the aromatic aldehydes and cellulose are analyzed.

  19. Catalytic Oxidation of Lignins into the Aromatic Aldehydes: General Process Trends and Development Prospects

    Science.gov (United States)

    Tarabanko, Valery E.; Tarabanko, Nikolay

    2017-01-01

    This review discusses principal patterns that govern the processes of lignins’ catalytic oxidation into vanillin (3-methoxy-4-hydroxybenzaldehyde) and syringaldehyde (3,5-dimethoxy-4-hydroxybenzaldehyde). It examines the influence of lignin and oxidant nature, temperature, mass transfer, and of other factors on the yield of the aldehydes and the process selectivity. The review reveals that properly organized processes of catalytic oxidation of various lignins are only insignificantly (10–15%) inferior to oxidation by nitrobenzene in terms of yield and selectivity in vanillin and syringaldehyde. Very high consumption of oxygen (and consequentially, of alkali) in the process—over 10 mol per mol of obtained vanillin—is highlighted as an unresolved and unexplored problem: scientific literature reveals almost no studies devoted to the possibilities of decreasing the consumption of oxygen and alkali. Different hypotheses about the mechanism of lignin oxidation into the aromatic aldehydes are discussed, and the mechanism comprising the steps of single-electron oxidation of phenolate anions, and ending with retroaldol reaction of a substituted coniferyl aldehyde was pointed out as the most convincing one. The possibility and development prospects of single-stage oxidative processing of wood into the aromatic aldehydes and cellulose are analyzed. PMID:29140301

  20. Production of alkyl-aromatics from light oxygenates over zeolite catalysts for bio-oil refining

    Science.gov (United States)

    Hoang, Trung Q.

    Upgrading of light oxygenates derived from biomass conversion, such as propanal and glycerol, to more valuable aromatics for biofuels has been demonstrated on zeolite catalysts. Aromatics with a high ratio of C 9/(C8+C7) and little benzene are produced at much higher yield from oxygenates than from olefins at mild conditions over HZSM-5. It is proposed that C9 aromatics are predominantly produced via acid-catalyzed aldol condensation. This reaction pathway is different from the pathway of propylene and other hydrocarbon aromatization that occurs via a hydrocarbon pool at more severe conditions with major aromatic products C6 and C7. In fact, investigation on the effect of crystallite size HZSM-5 has shown a higher ratio of C9/(C8+C 7) aromatics on small crystallite. This is due to faster removal of products from the shorter diffusion path length. As a result, a longer catalyst lifetime, less isomerization, and less cracking were observed on small crystallites. Beside crystallite size, pore geometry of zeolites was also found to significantly affect aromatic production for both conversion of propanal and glycerol. It is shown that the structure of the HZSM-22, with a one-dimensional and narrower channel system, restricts the formation of aromatics. In contrast, a higher yield of aromatic products is observed over HZSM-5 with its three-dimensional channel system. By increasing channel dimension and connectivity of the channels, increasing catalyst activity was also observed due to more accessible acid sites. It was also found that glycerol is highly active for dehydration on zeolites to produce high yields of acrolein (propenal), a high value chemical. To maximize aromatics from glycerol conversion, HZSM-5 and HY were found to be effective. A two-bed reactor of Pd/ZnO and HZSM-5 was used to first deoxygenate/hydrogenate glycerol over Pd/ZnO to intermediate oxygenates that can further aromatize on HZSM-5. The end results are very promising with significant improvement

  1. Polycyclic aromatic hydrocarbons in US and Swedish smokeless tobacco products

    Science.gov (United States)

    2013-01-01

    Background Debate about the health implications of using smokeless tobacco products (STPs) has prompted considerable interest in characterising their levels of toxic and carcinogenic components. In the present study seventy smokeless tobacco products from the US and Sweden, categorized as chewing tobacco, dry and moist snuff, hard and soft pellets, plug, and loose and portion snus, were analysed for twenty one polycyclic aromatic hydrocarbons (PAHs). The tested brands represented 80-90% of the 2008 market share for the major STP categories in these two countries. Results There were significant differences in the total and individual PAH concentrations in the different styles of product. Substantially higher levels of total PAHs (10–60 fold) were found in moist and dry snuff and soft pellets than in the other smokeless tobacco styles. The individual PAH concentrations followed the same patterns as total PAHs except for naphthalene, for which the highest concentrations were found in snus and moist snuff. Good correlations were obtained between benzo[a]pyrene (B[a]P) and all the other PAHs except naphthalene, 1-methylnaphthalene and 2-methylnaphthalene, providing evidence for the first time that it can be used as a good marker for PAHs in STPs. Results were generally in good agreement with two previous studies of PAHs in STPs, except for naphthalene for which significantly lower concentrations were found than previously reported. Analysis of the ratios of different PAHs confirmed that the use of fire-cured tobaccos in the snuffs and soft pellet were the major source of PAHs in these product styles, and provided, for the first time, some indications as to the source of PAHs in the other STP styles, including petrogenic and other combustion sources. Conclusions This study confirms the presence of PAHs in STPs, and identifies substantial differences between the levels in different STP categories. Since previous studies of naphthalene concentrations in STPs differed so

  2. Oxidation of aromatic alcohols by purified methanol dehydrogenase from Methylosinus trichosporium.

    OpenAIRE

    Mountfort, D O

    1990-01-01

    Methanol dehydrogenase was found to be present in subcellular preparations of methanol-grown Methylosinus trichosporium and occurred almost wholly in the soluble fraction of the cell. The enzyme, purified by DEAE-Sephadex and Sephadex G-100 chromatography, showed broad specificity toward different substrates and oxidized the aromatic alcohols benzyl, vanillyl, and veratryl alcohols in addition to a range of aliphatic primary alcohols. No enzyme activity was found toward the corresponding alde...

  3. Comparative study of the addition compounds between lanthanides methane sulfonates (III) and aromatic amino-oxides as ligands

    International Nuclear Information System (INIS)

    Rosario Matos, J. do.

    1989-01-01

    The main goal of this thesis is to further develop the studies on the preparation and characterization of addition compounds obtained from the reaction of lanthanide methane sulfonates and aromatic amino oxides as ligands, pyridine-N-oxides as the picoline-N-oxides (2-pic NO, 3-pic NO and 4-picNO) in order to make a comparative study. (author)

  4. Mild and Efficient Oxidation of Aromatic Alcohols and Other Substrates Using NiO2/CH3COOH System

    Directory of Open Access Journals (Sweden)

    Mohammad Kooti

    2008-01-01

    Full Text Available A variety of aromatic alcohols were efficiently oxidized to their corresponding aldehydes and ketones in good to excellent yields using nickel peroxide activated by acetic acid. Some thiols and amines were also readily oxidized by this oxidant under mild conditions.

  5. Aromatic hydrocarbons

    International Nuclear Information System (INIS)

    Roder, M.

    1985-01-01

    Papers dealing with radiolysis of aromatic hydrocarbons of different composition (from benzene to terphenyls and hydrocarbons with condensed rings) as well as their mixtures (with alkanes, alkenes, other aromatic hydrocarbons) are reviewed. High radiation stability of aromatic hydrocarbons in condensed phases associated with peculiarities of molecular structure of compounds is underlined. Mechanisms of radiolytic processes, vaues of product yields are considered

  6. Medicinal and aromatic crops: Production, Phytochemistry, and Utilization

    Science.gov (United States)

    In the later part of the 20th century the United States experienced a remarkable surge in public interest towards medicinal and aromatic crops and this trend continues. This consumer interest helped create a significant demand for plants with culinary and medicinal applications as the public discove...

  7. Kurdistan crude oils as feedstock for production of aromatics

    Directory of Open Access Journals (Sweden)

    Abdulsalam R. Karim

    2017-05-01

    Full Text Available Crude oils from various locations in Iraqi Kurdistan were fully evaluated, so that enables refiners to improve their operation by selecting the best crude oil that yields high naphtha content to be used as a catalytic reforming feedstock after determination of total sulfur content and then de sulfurizing them, then cyclizing or reforming these sweet naphtha cuts to produce aromatic fractions which can be split into benzene, toluene, and xylenes.

  8. Sensory and aromatic characteristics of tongue sole by-products hydrolysates (Cynoglossus senegalensis)

    OpenAIRE

    Sylla, K. S. B.; Berge, Jean-pascal; Prost, Carole; Musabyemariya, B.; Seydi, Mg

    2009-01-01

    Tongue sole by-products coming from fish-filleting plant were hydrolyzed by Protamex® protease. To identify the future application of hydrolysates, a sensory analysis was carried out.The sensory profile was performed with a jury of 14 specialized judges.11 profiles were found by this panel of tasting. In addition, the aromatic characterization revealed that 57 molecules are responsible for these odours described in sensory analysis.The description of these aromatic compounds opens potentia...

  9. Biological production of hydroxylated aromatics : Optimization strategies for Pseudomonas putida S12

    NARCIS (Netherlands)

    Verhoef, A.

    2010-01-01

    To replace environmentally unfriendly petrochemical production processes, the demand for bio-based production of organic chemicals is increasing. This thesis focuses on the biological production of hydroxylated aromatics from renewable substrates by engineered P. putida S12 including several cases

  10. Distributions of Polycyclic Aromatic Hydrocarbons, Aromatic Ketones, Carboxylic Acids, and Trace Metals in Arctic Aerosols: Long-Range Atmospheric Transport, Photochemical Degradation/Production at Polar Sunrise.

    Science.gov (United States)

    Singh, Dharmendra Kumar; Kawamura, Kimitaka; Yanase, Ayako; Barrie, Leonard A

    2017-08-15

    The distributions, correlations, and source apportionment of aromatic acids, aromatic ketones, polycyclic aromatic hydrocarbons (PAHs), and trace metals were studied in Canadian high Arctic aerosols. Nineteen PAHs including minor sulfur-containing heterocyclic PAH (dibenzothiophene) and major 6 carcinogenic PAHs were detected with a high proportion of fluoranthene followed by benzo[k]fluoranthene, pyrene, and chrysene. However, in the sunlit period of spring, their concentrations significantly declined likely due to photochemical decomposition. During the polar sunrise from mid-March to mid-April, benzo[a]pyrene to benzo[e]pyrene ratios significantly dropped, and the ratios diminished further from late April to May onward. These results suggest that PAHs transported over the Arctic are subjected to strong photochemical degradation at polar sunrise. Although aromatic ketones decreased in spring, concentrations of some aromatic acids such as benzoic and phthalic acids increased during the course of polar sunrise, suggesting that aromatic hydrocarbons are oxidized to result in aromatic acids. However, PAHs do not act as the major source for low molecular weight (LMW) diacids such as oxalic acid that are largely formed at polar sunrise in the arctic atmosphere because PAHs are 1 to 2 orders of magnitude less abundant than LMW diacids. Correlations of trace metals with organics, their sources, and the possible role of trace transition metals are explained.

  11. Prediction of activation energies for aromatic oxidation by cytochrome P450

    DEFF Research Database (Denmark)

    Rydberg, Patrik; Ryde, Ulf; Olsen, Lars

    2008-01-01

    We have estimated the activation energy for aromatic oxidation by compound I in cytochrome P450 for a diverse set of 17 substrates using state-of-the-art density functional theory (B3LYP) with large basis sets. The activation energies vary from 60 to 87 kJ/mol. We then test if these results can...... be reproduced by computationally less demanding methods. The best methods (a B3LYP calculation of the activation energy of a methoxy-radical model or a partial least-squares model of the semiempirical AM1 bond dissociation energies and spin densities of the tetrahedral intermediate for both a hydroxyl...

  12. Process for removing halogenated aliphatic and aromatic compounds from petroleum products

    Science.gov (United States)

    Googin, J.M.; Napier, J.M.; Travaglini, M.A.

    1983-09-20

    A process is described for removing halogenated aliphatic and aromatic compounds, e.g., polychlorinated biphenyls, from petroleum products by solvent extraction. The halogenated aliphatic and aromatic compounds are extracted from a petroleum product into a polar solvent by contacting the petroleum product with the polar solvent. The polar solvent is characterized by a high solubility for the extracted halogenated aliphatic and aromatic compounds, a low solubility for the petroleum product and considerable solvent power for polyhydroxy compound. The preferred polar solvent is dimethylformamide. A miscible compound, such as, water or a polyhydroxy compound, is added to the polar extraction solvent to increase the polarity of the polar extraction solvent. The halogenated aliphatic and aromatic compounds are extracted from the highly-polarized mixture of water or polyhydroxy compound and polar extraction solvent into a low polar or nonpolar solvent by contacting the water or polyhydroxy compound-polar solvent mixture with the low polar or nonpolar solvent. The halogenated aliphatic and aromatic compounds and the low polar or nonpolar solvent are separated by physical means, e.g., vacuum evaporation. The polar and nonpolar solvents are recovered from recycling. The process can easily be designed for continuous operation. Advantages of the process include that the polar solvent and a major portion of the nonpolar solvent can be recycled, the petroleum products are reclaimable and the cost for disposing of waste containing polychlorinated biphenyls is significantly reduced. 1 fig.

  13. Reaction of bromine and chlorine with phenolic compounds and natural organic matter extracts--Electrophilic aromatic substitution and oxidation.

    Science.gov (United States)

    Criquet, Justine; Rodriguez, Eva M; Allard, Sebastien; Wellauer, Sven; Salhi, Elisabeth; Joll, Cynthia A; von Gunten, Urs

    2015-11-15

    Phenolic compounds are known structural moieties of natural organic matter (NOM), and their reactivity is a key parameter for understanding the reactivity of NOM and the disinfection by-product formation during oxidative water treatment. In this study, species-specific and/or apparent second order rate constants and mechanisms for the reactions of bromine and chlorine have been determined for various phenolic compounds (phenol, resorcinol, catechol, hydroquinone, phloroglucinol, bisphenol A, p-hydroxybenzoic acid, gallic acid, hesperetin and tannic acid) and flavone. The reactivity of bromine with phenolic compounds is very high, with apparent second order rate constants at pH 7 in the range of 10(4) to 10(7) M(-1) s(-1). The highest value was recorded for the reaction between HOBr and the fully deprotonated resorcinol (k = 2.1 × 10(9) M(-1) s(-1)). The reactivity of phenolic compounds is enhanced by the activating character of the phenolic substituents, e.g. further hydroxyl groups. With the data set from this study, the ratio between the species-specific rate constants for the reactions of chlorine versus bromine with phenolic compounds was confirmed to be about 3000. Phenolic compounds react with bromine or chlorine either by oxidation (electron transfer, ET) or electrophilic aromatic substitution (EAS) processes. The dominant process mainly depends on the relative position of the hydroxyl substituents and the possibility of quinone formation. While phenol, p-hydroxybenzoic acid and bisphenol A undergo EAS, hydroquinone, catechol, gallic acid and tannic acid, with hydroxyl substituents in ortho or para positions, react with bromine by ET leading to quantitative formation of the corresponding quinones. Some compounds (e.g. phloroglucinol) show both partial oxidation and partial electrophilic aromatic substitution and the ratio observed for the pathways depends on the pH. For the reaction of six NOM extracts with bromine, electrophilic aromatic substitution

  14. Visible-light photoredox catalyzed synthesis of pyrroloisoquinolines via organocatalytic oxidation/[3 + 2] cycloaddition/oxidative aromatization reaction cascade with Rose Bengal

    Directory of Open Access Journals (Sweden)

    Carlos Vila

    2014-05-01

    Full Text Available Pyrrolo[2,1-a]isoquinoline alkaloids have been prepared via a visible light photoredox catalyzed oxidation/[3 + 2] cycloaddition/oxidative aromatization cascade using Rose Bengal as an organo-photocatalyst. A variety of pyrroloisoquinolines have been obtained in good yields under mild and metal-free reaction conditions.

  15. Selective Production of Aromatics from 2-Octanol on Zinc Ion-Exchanged MFI Zeolite Catalysts

    Directory of Open Access Journals (Sweden)

    Masakazu Iwamoto

    2015-12-01

    Full Text Available The aromatization of 2-octanol derived from castor oil as a byproduct in the formation of sebacic acid was investigated on various zeolite catalysts. Zn ion-exchanged MFI (ZSM-5 zeolites with small silica/alumina ratios and zinc contents of 0.5 to 2.0 wt. % were determined to exhibit good and stable activity for the reaction at 623 to 823 K. The yield of aromatics was 62% at 773 K and the space velocity 350 to 1400 h−1. The temperature and contact time dependences of the product distributions indicated the reaction pathways of 2-octanol→dehydration to 2-octene→decomposition to C5 and C3 compounds→further decomposition to small alkanes and alkenes→aromatization with dehydrogenation. Alcohols with carbon numbers of 5 to 8 exhibited similar distributions of products compared to 2-octanol, while corresponding carbonyl compounds demonstrated different reactivity.

  16. Carbonyl atmospheric reaction products of aromatic hydrocarbons in ambient air

    Science.gov (United States)

    Obermeyer, Genevieve; Aschmann, Sara M.; Atkinson, Roger; Arey, Janet

    To convert gaseous carbonyls to oximes during sampling, an XAD-4 resin denuder system pre-coated with O-(2,3,4,5,6-pentafluorobenzyl)hydroxylamine and followed by analysis with methane positive chemical ionization gas chromatography/mass spectrometry was used to measure carbonyls in ambient air samples in Riverside, CA. In conjunction with similar analyses of environmental chamber OH radical-initiated reactions of o- and p-xylene, 1,2,4-trimethylbenzene, ethylbenzene, 4-hydroxy-2-butanone and 1,4-butanediol, we identified benzaldehyde, o-, m- and p-tolualdehyde and acetophenone and the dicarbonyls glyoxal, methylglyoxal, biacetyl, ethylglyoxal, 1,4-butenedial, 3-hexene-2,5-dione, 3-oxo-butanal, 1,4-butanedial and malonaldehyde in the ambient air samples. As discussed, these carbonyls and dicarbonyls can be formed from the OH radical-initiated reactions of aromatic hydrocarbons and other volatile organic compounds emitted into the atmosphere, and we conclude that in situ atmospheric formation is a major source of these carbonyls in our Riverside, CA, ambient air samples.

  17. Lignin solubilization and aqueous phase reforming for the production of aromatic chemicals and hydrogen

    NARCIS (Netherlands)

    Zakzeski, J.|info:eu-repo/dai/nl/326160256; Weckhuysen, B.M.|info:eu-repo/dai/nl/285484397

    2011-01-01

    The solubilization and aqueous phase reforming of lignin, including kraft, soda, and alcell lignin along with sugarcane bagasse, at low temperatures (T≤498 K) and pressures (P≤29 bar) is reported for the first time for the production of aromatic chemicals and hydrogen. Analysis of lignin model

  18. Synthesis of extended polycyclic aromatic hydrocarbons by oxidative tandem spirocyclization and 1,2-aryl migration

    Science.gov (United States)

    Zhang, Xuan; Xu, Zhanqiang; Si, Weili; Oniwa, Kazuaki; Bao, Ming; Yamamoto, Yoshinori; Jin, Tienan

    2017-04-01

    The extended polycyclic aromatic hydrocarbons (PAHs) have received significant interdisciplinary attention due to their semiconducting applications in diverse organic electronics as well as intriguing structural interests of well-defined graphene segments. Herein, a highly efficient oxidative spirocyclization and 1,2-aryl migration tandem synthetic method for the construction of extended polyaromatic hydrocarbons (PAHs) has been developed. The CuCl-catalyst/PhCO3 tBu or DDQ oxidation system in the presence of trifluoroacetic acid enables the selective single-electron oxidation to take place preferentially at the more electron-rich alkene moiety of o-biphenylyl-substituted methylenefluorenes, giving rise to the subsequent tandem process. A variety of structurally diverse extended PAHs including functionalized dibenzo[g,p]chrysenes, benzo[f]naphtho[1,2-s]picene, hexabenzo[a,c,fg,j,l,op]tetracene, tetrabenzo[a,c,f,m]phenanthro[9,10-k]tetraphene, tetrabenzo[a,c,f,k]phenanthro[9,10-m]tetraphene, tetrabenzo[a,c,f,o]phenanthro[9,10-m]picene and S-type helicene have been readily synthesized.

  19. Photodegradation of polycyclic aromatic hydrocarbon pyrene by iron oxide in solid phase

    International Nuclear Information System (INIS)

    Wang, Y.; Liu, C.S.; Li, F.B.; Liu, C.P.; Liang, J.B.

    2009-01-01

    To better understand the photodegradation of polycyclic aromatic hydrocarbons (PAH) in solid phase in natural environment, laboratory experiments were conducted to study the influencing factors, kinetics and intermediate compound of pyrene photodegradation by iron oxides. The results showed that the pyrene photodegradation rate followed the order of α-FeOOH > α-Fe 2 O 3 > γ-Fe 2 O 3 > γ-FeOOH at the same reaction conditions. Lower dosage of α-FeOOH and higher light intensity increased the photodegradation rate of pyrene. Iron oxides and oxalic acid can set up a photo-Fenton-like system without additional H 2 O 2 in solid phase to enhance the photodegradation of pyrene under UV irradiation. All reaction followed the first-order reaction kinetics. The half-life (t 1/2 ) of pyrene in the system showed the higher efficiencies of using iron oxide as photocatalyst to degrade pyrene. Intermediate compound pyreno was found during photodegradation reactions by gas chromatography-mass spectrometry (GC-MS). The photodegradation efficiency for PAHs in this photo-Fenton-like system was also confirmed by using the contaminated soil samples. This work provides some useful information to understand the remediation of PAHs contaminated soils by photochemical techniques under practical condition

  20. OH-radical induced degradation of hydroxybenzoic- and hydroxycinnamic acids and formation of aromatic products-A gamma radiolysis study

    Energy Technology Data Exchange (ETDEWEB)

    Krimmel, Birgit; Swoboda, Friederike [University of Vienna, Department of Nutritional Sciences, Section Radiation Biology (Austria); Solar, Sonja, E-mail: sonja.solar@univie.ac.a [University of Vienna, Department of Nutritional Sciences, Section Radiation Biology (Austria); Reznicek, Gottfried [Department of Pharmacognosy, Althanstrasse 14, A-1090 Vienna (Austria)

    2010-12-15

    The OH-radical induced degradation of hydroxybenzoic acids (HBA), hydroxycinnamic acids (HCiA) and methoxylated derivatives, as well as of chlorogenic acid and rosmarinic acid was studied by gamma radiolysis in aerated aqueous solutions. Primary aromatic products resulting from an OH-radical attachment to the ring (hydroxylation), to the position occupied by the methoxyl group (replacement -OCH{sub 3} by -OH) as well as to the propenoic acid side chain of the cinnamic acids (benzaldehyde formations) were analysed by HPLC-UV and LC-ESI-MS. A comparison of the extent of these processes is given for 3,4-dihydroxybenzoic acid, vanillic acid, isovanillic acid, syringic acid, cinnamic acid, 4-hydroxycinnamic acid, caffeic acid, ferulic acid, isoferulic acid, chlorogenic acid, and rosmarinic acid. For all cinnamic acids and derivatives benzaldehydes were significant oxidation products. With the release of caffeic acid from chlorogenic acid the cleavage of a phenolic glycoside could be demonstrated. Reaction mechanisms are discussed.

  1. Hydrodeoxygenation of oxidized distilled bio-oil for the production of gasoline fuel type

    International Nuclear Information System (INIS)

    Luo, Yan; Guda, Vamshi Krishna; Hassan, El Barbary; Steele, Philip H.; Mitchell, Brian; Yu, Fei

    2016-01-01

    Highlights: • Oxidation had more influence on the yield of total hydrocarbons than distillation. • The highest total hydrocarbon yield was obtained from oxidized distilled bio-oil. • The 2nd-stage hydrocarbons were in the range of gasoline fuel boiling points. • The main products for upgrading of oxidized bio-oil were aliphatic hydrocarbons. • The main products for upgrading of non-oxidized bio-oil were aromatic hydrocarbons. - Abstract: Distilled and oxidized distilled bio-oils were subjected to 1st-stage mild hydrodeoxygenation and 2nd-stage full hydrodeoxygenation using nickel/silica–alumina catalyst as a means to enhance hydrocarbon yield. Raw bio-oil was treated for hydrodeoxygenation as a control to which to compare study treatments. Following two-stage hydrodeoxygenation, four types of hydrocarbons were mainly comprised of gasoline and had water contents, oxygen contents and total acid numbers of nearly zero and higher heating values of 44–45 MJ/kg. Total hydrocarbon yields for raw bio-oil, oxidized raw bio-oil, distilled bio-oil and oxidized distilled bio-oil were 11.6, 16.2, 12.9 and 20.5 wt.%, respectively. The results indicated that oxidation had the most influence on increasing the yield of gasoline fuel type followed by distillation. Gas chromatography/mass spectrometry characterization showed that 66.0–76.6% of aliphatic hydrocarbons and 19.5–31.6% of aromatic hydrocarbons were the main products for oxidized bio-oils while 35.5–38.7% of aliphatic hydrocarbons and 58.2–63.1% of aromatic hydrocarbons were the main products for non-oxidized bio-oils. Both aliphatic and aromatic hydrocarbons are important components for liquid transportation fuels and chemical products.

  2. Production of Monomeric Aromatic Compounds from Oil Palm Empty Fruit Bunch Fiber Lignin by Chemical and Enzymatic Methods

    Directory of Open Access Journals (Sweden)

    Pei-Ling Tang

    2015-01-01

    Full Text Available In this study, oil palm empty fruit bunch (OPEFBF was pretreated with alkali, and lignin was extracted for further degradation into lower molecular weight phenolic compounds using enzymes and chemical means. Efficiency of monomeric aromatic compounds production from OPEFBF lignin via chemical (nitrobenzene versus oxygen and enzymatic [cutinase versus manganese peroxidase (MnP] approaches was investigated. The effects of sodium hydroxide concentration (2, 5, and 10% wt. and reaction time (30, 90, and 180 minutes on the yield of aromatic compounds were studied. The results obtained indicated that nitrobenzene oxidation produced the highest yield (333.17±49.44 ppm hydroxybenzoic acid, 5.67±0.25 ppm p-hydroxybenzaldehyde, 25.57±1.64 ppm vanillic acid, 168.68±23.23 ppm vanillin, 75.44±6.71 ppm syringic acid, 815.26±41.77 ppm syringaldehyde, 15.21±2.19 ppm p-coumaric acid, and 44.75±3.40 ppm ferulic acid, among the tested methods. High sodium hydroxide concentration (10% wt. was needed to promote efficient nitrobenzene oxidation. However, less severe oxidation condition was preferred to preserve the hydroxycinnamic acids (p-coumaric acid and ferulic acid. Cutinase-catalyzed hydrolysis was found to be more efficient than MnP-catalyzed oxidation in the production of aromatic compounds. By hydrolyzed 8% wt. of lignin with 0.625 mL cutinase g−1 lignin at pH 8 and 55°C for 24 hours, about 642.83±14.45 ppm hydroxybenzoic acid, 70.19±3.31 ppm syringaldehyde, 22.80±1.04 ppm vanillin, 27.06±1.20 ppm p-coumaric acid, and 50.19±2.23 ppm ferulic acid were produced.

  3. Effects of methyl group on aromatic hydrocarbons on the nanostructures and oxidative reactivity of combustion-generated soot

    KAUST Repository

    Guerrero Peñ a, Gerardo D.J.; Alrefaai, Mhd Maher; Yang, Seung Yeon; Raj, Abhijeet; Brito, Joaquin L.; Stephen, Samuel; Anjana, Tharalekshmy; Pillai, Vinu; Al Shoaibi, Ahmed; Chung, Suk-Ho

    2016-01-01

    The substituted and unsubstituted aromatic hydrocarbons, present in transportation fuels such as gasoline and diesel, are thought to be responsible for most of the soot particles produced during their combustion. However, the effects of the substituted alkyl groups on the aromatic hydrocarbons on their sooting tendencies, and on the physical and chemical properties of soot produced from them are not well understood. In this work, the effect of the presence of methyl groups on aromatic hydrocarbons on their sooting propensity, and on the oxidative reactivity, morphology, and chemical composition of soot generated from them in diffusion flames is studied using benzene, toluene, and m-xylene as fuels. Several experimental techniques including high resolution transmission electron microscopy and X-ray diffraction are used to identify the morphological changes in soot, whereas the elemental and thermo-gravimetric analyses, electron energy loss spectroscopy, and Fourier transform infrared spectroscopy are used to study the changes in its chemical properties and reactivity. The activation energies for soot oxidation are calculated at different conversion levels, and a trend in the reactivity of soots from benzene, toluene and m-xylene is reported. It is observed that the sizes of primary particles and graphene-like sheets, and the concentrations of aliphatics and oxygenated groups in soot particles decreased with the addition of methyl group(s) on the aromatic ring. The physicochemical changes in soot are found to support the oxidative reactivity trends. © 2016 The Combustion Institute

  4. Effects of methyl group on aromatic hydrocarbons on the nanostructures and oxidative reactivity of combustion-generated soot

    KAUST Repository

    Guerrero Peña, Gerardo D.J.

    2016-07-23

    The substituted and unsubstituted aromatic hydrocarbons, present in transportation fuels such as gasoline and diesel, are thought to be responsible for most of the soot particles produced during their combustion. However, the effects of the substituted alkyl groups on the aromatic hydrocarbons on their sooting tendencies, and on the physical and chemical properties of soot produced from them are not well understood. In this work, the effect of the presence of methyl groups on aromatic hydrocarbons on their sooting propensity, and on the oxidative reactivity, morphology, and chemical composition of soot generated from them in diffusion flames is studied using benzene, toluene, and m-xylene as fuels. Several experimental techniques including high resolution transmission electron microscopy and X-ray diffraction are used to identify the morphological changes in soot, whereas the elemental and thermo-gravimetric analyses, electron energy loss spectroscopy, and Fourier transform infrared spectroscopy are used to study the changes in its chemical properties and reactivity. The activation energies for soot oxidation are calculated at different conversion levels, and a trend in the reactivity of soots from benzene, toluene and m-xylene is reported. It is observed that the sizes of primary particles and graphene-like sheets, and the concentrations of aliphatics and oxygenated groups in soot particles decreased with the addition of methyl group(s) on the aromatic ring. The physicochemical changes in soot are found to support the oxidative reactivity trends. © 2016 The Combustion Institute

  5. Adsorption and Oxidation of Aromatic Amines on Metal(II Hexacyanocobaltate(III Complexes: Implication for Oligomerization of Exotic Aromatic Compounds

    Directory of Open Access Journals (Sweden)

    Rachana Sharma

    2017-03-01

    Full Text Available Based on the hypothesis on the presence of double metal cyanides in the primordial oceans, a series of nano-sized metal(II hexacyanocobaltate(III (MHCCo with the general formula: M3[Co(CN6]2•xH2O (where M = Zn, Fe, Ni and Mn has been synthesized. Surface interaction of aromatic amines, namely aniline, 4-chloroaniline, 4-methylaniline and 4-methoxyaniline with MHCCo particles has been carried out at the concentration range of 100–400 μM at pH~7.0. The percentage binding of aromatic amines on MHCCo surface was found to be in the range of 84%–44%. The trend in adsorption was in accordance to the relative basicity of the studied amines. At the experimental pH, amines reacted rapidly with the surface of the iron(II hexacyanocobaltate, producing colored products that were analyzed by Gas Chromatography Mass Spectroscopy (GC-MS. GC-MS analysis of the colored products demonstrated the formation of dimers of the studied aromatic amines. Surface interaction of aromatic amines with MHCCo was studied by Fourier Transform Infrared (FT-IR spectroscopy and Field Emission Scanning Electron Microscopy (FE-SEM. The change in amine characteristic frequencies, as observed by FT-IR, suggests that interaction took place through the NH2 group on amines with metal ions of hexacyanocobaltate complexes. FE-SEM studies revealed the adherence of 4-methoxyaniline on zinc hexacyanocobaltate particles surface. We proposed that MHCCo might have been formed under the conditions on primitive Earth and may be regarded as an important candidate for concentrating organic molecules through the adsorption process.

  6. Voltammetry coupled to mass spectrometry in the presence of isotope {sup 18}O labeled water for the prediction of oxidative transformation pathways of activated aromatic ethers: Acebutolol

    Energy Technology Data Exchange (ETDEWEB)

    Bussy, Ugo; Tea, Illa [LUNAM Université de Nantes, CNRS, Chimie et Interdisciplinarité: Synthèse, Analyse et Modélisation (CEISAM), UMR 6230, 2 rue de la Houssinière, BP 92208, F-44322 Nantes cedex 3 (France); Ferchaud-Roucher, Véronique; Krempf, Michel [Université de Nantes, Plateforme Spectrométrie de Masse, CRNH, SFR Santé F. Bonamy, Institut du Thorax, UMR S1087, IRT-UN, BP 70721, 8 Quai Moncousu, 44007 Nantes cedex 1 (France); Silvestre, Virginie; Galland, Nicolas [LUNAM Université de Nantes, CNRS, Chimie et Interdisciplinarité: Synthèse, Analyse et Modélisation (CEISAM), UMR 6230, 2 rue de la Houssinière, BP 92208, F-44322 Nantes cedex 3 (France); Jacquemin, Denis [LUNAM Université de Nantes, CNRS, Chimie et Interdisciplinarité: Synthèse, Analyse et Modélisation (CEISAM), UMR 6230, 2 rue de la Houssinière, BP 92208, F-44322 Nantes cedex 3 (France); Institut Universitaire de France, 103, Boulevard Saint-Michel, 75005 Cedex 5 France (France); Andresen-Bergström, Moa; Jurva, Ulrik [CVGI iMed DMPK, AstraZeneca R and D Mölndal, Mölndal (Sweden); and others

    2013-01-31

    Highlights: ► Voltammetry coupled to mass spectrometry method as a useful tool for on-line predictions of electrochemical transformations. ► Evidence of the O-dealkoxylation reaction pathway of acebutolol in the presence of labeled water. ► New approach for on line EC-MS applications. -- Abstract: The coupling between an electrochemical cell (EC) and a mass spectrometer (MS) is a useful screening tool (EC-MS) to study the oxidative transformation pathways of various electroactive species. For that purpose, we showed that the EC-MS method, carried out in the presence and absence of isotope {sup 18}O labeled water leads not only to a fast identification of oxidation products but also leads to a fast elucidation of the mechanism pathway reaction. We examined herein the case of the electrochemical hydrolysis of activated aromatic ether. Acebutolol (β-blockers) was selected herein as model of activated aromatic ether, and its electrochemical oxidation was examined in both the presence and absence of isotope {sup 18}O labeled water. To elucidate electrochemical hydrolysis pathway reaction: O-dealkylation or O-dealkoxylation, our approach was used to prove its applicability. The electrochemical oxidation mechanism was then elucidated showing an O-dealkoxylation reaction. In addition, density functional theory (DFT) calculations fully support the experimental conclusions.

  7. Activated carbon as catalyst for microwave-assisted wet peroxide oxidation of aromatic hydrocarbons.

    Science.gov (United States)

    Garcia-Costa, Alicia L; Lopez-Perela, Lucia; Xu, Xiyan; Zazo, Juan A; Rodriguez, Juan J; Casas, Jose A

    2018-05-21

    This paper addresses the removal of four aromatic hydrocarbons typically found in petrochemical wastewater: benzene (B), toluene (T), o-xylene (X), and naphthalene (N), by microwave-assisted catalytic wet peroxide oxidation (MW-CWPO) using activated carbon (AC) as catalyst. Under the studied conditions, complete pollutant elimination (B, 1.28 mM; T, 1.09 mM; X, 0.94 mM; and N, 0.78 mM) was achieved, with more than 90% TOC removal after only 15-min reaction time, working at 120 °C, pH 0  = 3, AC at 1 g L -1 , and H 2 O 2 at the stoichiometric dose. Furthermore, in the case of toluene, naphthalene, and xylene, the hydroxylation and breakdown of the ring is very rapid and toxic intermediates were not detected. The process follows two steps: (i) pollutant adsorption onto AC followed by (ii) adsorbed compounds oxidation. Thus, MW-CWPO with AC as catalyst appears a promising way for a fast and effective process for B, T, X, and N removal in aqueous phase.

  8. Technological surveillance of aromatic species : from research to the consolidation of the productive chain in Colombia

    Directory of Open Access Journals (Sweden)

    Adriana Patricia Tofiño-Rivera,

    2017-05-01

    Full Text Available The sector of aromatic, medicinal and seasoning herbs brings together a wide variety of native and introduced species with agroindustrial potential. In order to contribute to the technological assessment of the sector in Colombia and provide elements of strategic planning towards higher levels of development and internationalization. We prioritized certain aromatic species in this article and a technological surveillance was made during 2004-2014. A searching scientific articles and patents was made in eight national, iberoamericanand worldwide databases according prioritized issues. Data processing was performed using Microsoft Excel, EndNote, Vantage Point (2014 Thomson Data Analyzer programs. At National level, the planting material and breeding has been the main researched topic; whereas in iberoamerica and the world was biocidal effect. The leading countries in research on the monitored aromatic plants were Brazil, Colombia and Cuba. Internationally, the scientific leaders according to PubMed and Scopus were India, USA, Brazil and Colombia. The global trend in the field of patents has increased, whose main focus is: “Current needs of life”. This technological surveillance gives an overview of developments and trends in research and technological development in different subject areas within the aromatic plants, besides identifying possible allied research and the scientific production trends over time.

  9. Transformations of Aromatic Compounds by Nitrosomonas europaea

    OpenAIRE

    Keener, William K.; Arp, Daniel J.

    1994-01-01

    Benzene and a variety of substituted benzenes inhibited ammonia oxidation by intact cells of Nitrosomonas europaea. In most cases, the inhibition was accompanied by transformation of the aromatic compound to a more oxidized product or products. All products detected were aromatic, and substituents were often oxidized but were not separated from the benzene ring. Most transformations were enhanced by (NH4)2SO4 (12.5 mM) and were prevented by C2H2, a mechanism-based inactivator of ammonia monoo...

  10. Optimizing the Production of Renewable Aromatics via Crop Oil Catalytic Cracking

    Directory of Open Access Journals (Sweden)

    Clancy Kadrmas

    2015-04-01

    Full Text Available While HZSM-5 catalytic cracking of crop oil toward aromatics have been well documented, this work adds to this body of knowledge with a full acid byproduct analysis that provides improved mass balance closure along with a design of experiment optimization of reaction conditions. Fatty acids are an inevitable byproduct when converting any triglyceride oil, but are most often overlooked; despite the impact fatty acids have on downstream processing. Acid analysis verified that only short chain fatty acids, mainly acetic acid, were present in low quantities when all feed oil was reacted. When relatively high fatty acid amounts were present, these were mainly uncracked C16 and C18 fatty acids. Optimization is a balance of aromatics formation vs. unwanted gas products, coke and residual fatty acids. A design of experiments approach was used to provide insight into where the optimal reaction conditions reside for HZSM-5 facilitated reactions. These conditions can then form the basis for further development into a commercially viable process for the production of renewable aromatics and other byproducts.

  11. Adsorption of polycyclic aromatic hydrocarbons by graphene and graphene oxide nanosheets.

    Science.gov (United States)

    Wang, Jun; Chen, Zaiming; Chen, Baoliang

    2014-05-06

    The adsorption of naphthalene, phenanthrene, and pyrene onto graphene (GNS) and graphene oxide (GO) nanosheets was investigated to probe the potential adsorptive sites and molecular mechanisms. The microstructure and morphology of GNS and GO were characterized by elemental analysis, XPS, FTIR, Raman, SEM, and TEM. Graphene displayed high affinity to the polycyclic aromatic hydrocarbons (PAHs), whereas GO adsorption was significantly reduced after oxygen-containing groups were attached to GNS surfaces. An unexpected peak was found in the curve of adsorption coefficients (Kd) with the PAH equilibrium concentrations. The hydrophobic properties and molecular sizes of the PAHs affected the adsorption of G and GO. The high affinities of the PAHs to GNS are dominated by π-π interactions to the flat surface and the sieving effect of the powerful groove regions formed by wrinkles on GNS surfaces. In contrast, the adsorptive sites of GO changed to the carboxyl groups attaching to the edges of GO because the groove regions disappeared and the polar nanosheet surfaces limited the π-π interactions. The TEM and SEM images initially revealed that after loading with PAH, the conformation and aggregation of GNS and GO nanosheets dramatically changed, which explained the observations that the potential adsorption sites of GNS and GO were unusually altered during the adsorption process.

  12. Gas-phase Precursors to Anthropogenic SOA: Using the MCM to Probe Detailed Observations of Aromatic Photo-oxidation

    Science.gov (United States)

    Rickard, A. R.; Wyche, K. P.; Metzger, A.; Monks, P. S.; Ellis, A. M.; Baltensperger, U.; Pilling, M. J.; Jenkin, M. E.

    2008-12-01

    The formation of photochemical ozone and particulate matter are major priorities in the determination of European air quality policies. Predictions of the future state of the atmosphere and the development of appropriate mitigation strategies rely on models, which necessarily incorporate chemistry. The Master Chemical Mechanism (MCM, http://mcm.leeds.ac.uk/MCM) is a near-explicit chemical mechanism originally conceived to model ozone formation in Europe but now also employed as a benchmark mechanism in a wide variety of applications where chemical detail is required. The MCM currently describes the detailed gas- phase tropospheric degradation of a 135 primary emitted volatile organic compounds (VOCs) leading to a mechanism containing ca. 5900 species and 13500 reactions. In order that the MCM continues to be a state-of-the-art resource for the atmospheric science community it resides under a constant regime of evaluation, development and improvement. Individual VOC photochemical mechanisms are evaluated using data obtained, under a variety of atmospheric conditions, from highly instrumented smog chambers. Smog chamber experiments are crucial, not only for mechanism evaluation, but also for mechanism development. Findings obtained from combined model and chamber studies can additionally provide key insight for guiding the directions of future laboratory experiments. Recently, the MCM was updated to MCMv3.1 in order to take into account recent advancements in the understanding of aromatic photo-oxidation, an important class of anthropogenic VOCs. As well as constituting precursors to secondary organic aerosol (SOA), aromatics generally have high photochemical ozone creation potentials (POCPs) and hence contribute significantly towards tropospheric ozone formation. In the work presented, a detailed gas-phase photochemical chamber box model, incorporating the MCMv3.1 degradation mechanism for 1,3,5-trimethylbenzene (TMB), has been used to simulate data measured during

  13. Transparent conducting oxides and production thereof

    Science.gov (United States)

    Gessert, Timothy A.; Yoshida, Yuki; Coutts, Timothy J.

    2014-06-10

    Transparent conducting oxides and production thereof are disclosed. An exemplary method of producing a transparent conducting oxide (TCO) material may comprise: providing a TCO target doped with either a high-permittivity oxide or a low-permittivity oxide in a process chamber. The method may also comprise depositing a metal oxide on the target in the process chamber to form a thin film having enhanced optical properties without substantially decreasing electrical quality.

  14. Comparison of UV irradiation and p-fluorphenylaline as selective agents for production of aromatic compounds in plant cell culture

    International Nuclear Information System (INIS)

    Quesnel, A.A.; Ellis, B.E.

    1989-01-01

    Resistance to UV irradiation, and to the toxicity of p-fluorophenylalanine, can both be mediateted in plants by enhanced synthesis of aromatic compounds. These selective agents were applied to cell cultures of Nicotiana tabacum, Anchusa officinalis and Catharanthus roseur, and the production of aromatic metabolites in the resulting resistant lines of each species was compared. While Nicotiana and Anchusa cultures responded to each selective agent ith an enhanced accumulation of aromatic compounds, the Catharanthus cultures acquired resistance through other, unknown, mechanisms. Some degree of cross-resistance was observed between cultures selected individually for resistance to each agent (author). 26 refs.; 2 figs.; 1 tab

  15. Catalytic oxidation of o-aminophenols and aromatic amines by mushroom tyrosinase.

    Science.gov (United States)

    Muñoz-Muñoz, Jose Luis; Garcia-Molina, Francisco; Garcia-Ruiz, Pedro Antonio; Varon, Ramon; Tudela, Jose; Rodriguez-Lopez, Jose N; Garcia-Canovas, Francisco

    2011-12-01

    The kinetics of tyrosinase acting on o-aminophenols and aromatic amines as substrates was studied. The catalytic constants of aromatic monoamines and o-diamines were both low, these results are consistent with our previous mechanism in which the slow step is the transfer of a proton by a hydroxyl to the peroxide in oxy-tyrosinase (Fenoll et al., Biochem. J. 380 (2004) 643-650). In the case of o-aminophenols, the hydroxyl group indirectly cooperates in the transfer of the proton and consequently the catalytic constants in the action of tyrosinase on these compounds are higher. In the case of aromatic monoamines, the Michaelis constants are of the same order of magnitude than for monophenols, which suggests that the monophenols bind better (higher binding constant) to the enzyme to facilitate the π-π interactions between the aromatic ring and a possible histidine of the active site. In the case of aromatic o-diamines, both the catalytic and Michaelis constants are low, the values of the catalytic constants being lower than those of the corresponding o-diphenols. The values of the Michaelis constants of the aromatic o-diamines are slightly lower than those of their corresponding o-diphenols, confirming that the aromatic o-diamines bind less well (lower binding constant) to the enzyme. Copyright © 2011 Elsevier B.V. All rights reserved.

  16. Oxidation of aromatic amines and diamines by OH radicals. Formation and ionization constants of amine cation radicals in water

    International Nuclear Information System (INIS)

    Hayon, E.; Rao, P.S.

    1975-01-01

    The one-electron oxidation by hydroxyl radicals of aromatic amines and diamines in water was studied using the fast-reaction technique of pulse radiolysis and kinetic absorption spectrophotometry. The following compounds were examined: N,N,N 1 ,N 1 - tetramethyl-p-phenylenediamine (TMPD), p-phenylenediamine (PD), N,N-dimethyl-p-phenylenediamene (DMPD), N,N,N 1 ,N 1 -tetramethylbenzidine (TMB), and diphenylamine (DPA). The main initial reaction of the OH radicals is suggested to be an addition to these compounds to give absorption spectra which absorb strongly in the visible and uv regions. These OH radical adducts decay by first-order kinetics and have lifetimes of approximately 5-50 μsec, dependent on the pH, buffer concentration, and the nature of the aromatic amines and diamines. They decay to give species with somewhat similar absorption spectra and extinction coefficients, which are very long lived in the absence of oxygen. The latter species are assigned to the cation radicals TMPD. + , PD. + , DMPD. + , TMB. + , and DPA. + . The OH radical adducts and the cation radicals have acid-base properties. The pK/sub a/ values of the cation radicals TMPDH. 2+ , PDH. 2+ , DMPDH. 2+ , TMBH. 2+ , and DPAH. 2+ were found to be 5.3, 5.9, 6.1, 5.1, and 4.2, respectively. The results indicate that these aromatic amines and diamines can be oxidized by free radicals to yield the corresponding cation radicals. (U.S.)

  17. Photocatalytic oxidation of polycyclic aromatic hydrocarbons: Intermediates identification and toxicity testing

    International Nuclear Information System (INIS)

    Woo, O.T.; Chung, W.K.; Wong, K.H.; Chow, Alex T.; Wong, P.K.

    2009-01-01

    Polycyclic aromatic hydrocarbons (PAHs) are hydrophobic pollutants and their low water solubility limits their degradation in aqueous solution. The presence of water-miscible solvent such as acetone can increase the water solubility of PAHs, however acetone will also affect the degradation of PAH. In this study the effects of acetone on the photocatalytic degradation efficiency and pathways of 5 selected PAHs, namely naphthalene (2 rings), acenaphthylene (3 rings), phenanthrene (3 rings), anthracene (3 rings) and benzo[a]anthracene (4 rings) were investigated. The Microtox toxicity test was used to determine whether the PCO system can completely detoxify the parental PAHs and its intermediates. The addition of 16% acetone can greatly alter the degradation pathway of naphthalene and anthracene. Based on intermediates identified from degradation of the 5 PAHs, the location of parental PAHs attacked by reactive free radicals can be correlated with the localization energies of different positions of the compound. For toxicity analysis, irradiation by UV light was found to induce acute toxicity by generating intermediates/degradation products from PAHs and possibly acetone. Lastly, all PAHs (10 mg l -1 ) can be completely detoxified by titanium dioxide (100 mg l -1 ) within 24 h under UVA irradiation (3.9 mW cm -2 ).

  18. Identification and characterization of epoxide hydrolase activity of polycyclic aromatic hydrocarbon-degrading bacteria for biocatalytic resolution of racemic styrene oxide and styrene oxide derivatives.

    Science.gov (United States)

    Woo, Jung-Hee; Kwon, Tae-Hyung; Kim, Jun-Tae; Kim, Choong-Gon; Lee, Eun Yeol

    2013-04-01

    A novel epoxide hydrolase (EHase) from polycyclic aromatic hydrocarbon (PAH)-degrading bacteria was identified and characterized. EHase activity was identified in four strains of PAH-degrading bacteria isolated from commercial gasoline and oil-contaminated sediment based on their growth on styrene oxide and its derivatives, such as 2,3- and 4-chlorostyrene oxides, as a sole carbon source. Gordonia sp. H37 exhibited high enantioselective hydrolysis activity for 4-chlorostyrene oxide with an enantiomeric ratio of 27. Gordonia sp. H37 preferentially hydrolyzed the (R)-enantiomer of styrene oxide derivatives resulting in the preparation of a (S)-enantiomer with enantiomeric excess greater than 99.9 %. The enantioselective EHase activity was identified and characterized in various PAH-degrading bacteria, and whole cell Gordonia sp. H37 was employed as a biocatalyst for preparing enantiopure (S)-styrene oxide derivatives.

  19. Effects of mycorrhiza on growth and essential oil production in selected aromatic plants

    Directory of Open Access Journals (Sweden)

    Waed Tarraf

    2015-09-01

    Full Text Available Arbuscular mycorrhizal (AM symbiosis is widely investigated in aromatic herbs. Several studies have shown different effects on secondary metabolites, biomass production, as well as oil quantitative and qualitative aspects. The seeking to increase the yield of plants and their oils is an interesting topic in the world of medicinal and aromatic plant production. In tune with that, this study evaluated the effectiveness of two mycorrhiza fungi, Funneliformis mosseae (syn. Glomus mosseae and Septoglomus viscosum (syn. Glomus viscosum, on three species from Lamiaceae family: Salvia officinalis L., Origanum vulgare L., and Thymus vulgaris L. besides untreated control. It was found that the effect of symbiosis on growth was more favourable with S. viscosum than other AM fungus. The S. viscosum inoculation raised the yield of essential oil in oregano. Analysis of gas chromatography/mass spectrometry showed that manool obtained the highest abundance in leaf essential oil of inoculated sage; thymol was the major component whatever the treatment in thyme and lower relative content of carvacrol was reported with arbuscular mycorrhizal fungi inoculation in oregano. The results suggest the mycorrhizal inoculation as a promising technology in sustainable agricultural system to improve the plant productivity performance. Specific inocula are strategic to enhance the chemical profile of essential oils.

  20. Process for removing halogenated aliphatic and aromatic compounds from petroleum products. [Polychlorinated biphenyls; methylene chloride; perchloroethylene; trichlorofluoroethane; trichloroethylene; chlorobenzene

    Science.gov (United States)

    Googin, J.M.; Napier, J.M.; Travaglini, M.A.

    1982-03-31

    A process for removing halogenated aliphatic and aromatic compounds, e.g., polychlorinated biphenyls, from petroleum products by solvent extraction. The halogenated aliphatic and aromatic compounds are extracted from a petroleum product into a polar solvent by contracting the petroleum product with the polar solvent. The polar solvent is characterized by a high solubility for the extracted halogenated aliphatic and aromatic compounds, a low solubility for the petroleum product and considerable solvent power for polyhydroxy compound. The preferred polar solvent is dimethylformamide. A miscible polyhydroxy compound, such as, water, is added to the polar extraction solvent to increase the polarity of the polar extraction solvent. The halogenated aliphatic and aromatic compounds are extracted from the highly-polarized mixture of polyhydroxy compound and polar extraction solvent into a low polar or nonpolar solvent by contacting the polyhydroxy compound-polar solvent mixture with the low polar or nonpolar solvent. The halogenated aliphatic and aromatic compounds in the low polar or nonpolar solvent by physical means, e.g., vacuum evaporation. The polar and nonpolar solvents are recovered for recycling. The process can easily be designed for continuous operation. Advantages of the process include that the polar solvent and a major portion of the nonpolar solvent can be recycled, the petroleum products are reclaimable and the cost for disposing of waste containing polychlorinated biphenyls is significantly reduced. 2 tables.

  1. Kinetics and Mechanism of Oxidation of Aromatic Aldehydes by Imidazolium Dichromate in Aqueous Acetic Acid Medium

    Directory of Open Access Journals (Sweden)

    S. Sheik Mansoor

    2009-01-01

    Full Text Available The kinetics of oxidation of benzaldehyde (BA and para-substituted benzaldehydes by imidazolium dichromate (IDC has been studied in aqueous acetic acid medium in the presence of perchloric acid. The reaction is first order each in [IDC], [Substrate] and [H+]. The reaction rates have been determined at different temperatures and the activation parameters calculated. Electron withdrawing substituents are found to increase the reaction and electron releasing substituents are found to retard the rate of the reaction and the rate data obey the Hammett relationship. The products of the oxidation are the corresponding acids. The rate decreases with the increase in the water content of the medium. A suitable mechanism is proposed.

  2. Influence of Tunisian aromatic plants on the prevention of oxidation in soybean oil under heating and frying conditions.

    Science.gov (United States)

    Saoudi, Salma; Chammem, Nadia; Sifaoui, Ines; Bouassida-Beji, Maha; Jiménez, Ignacio A; Bazzocchi, Isabel L; Silva, Sandra Diniz; Hamdi, Moktar; Bronze, Maria Rosário

    2016-12-01

    The aim of this study was to improve the oxidative stability of soybean oil by using aromatic plants. Soybean oil flavored with rosemary (ROS) and soybean oil flavored with thyme (THY) were subjected to heating for 24h at 180°C. The samples were analyzed every 6h for their total polar compounds, anisidine values, oxidative stability and polyphenols content. The tocopherols content was determined and volatile compounds were also analyzed. After 24h of heating, the incorporation of these plants using a maceration process reduced the polar compounds by 69% and 71% respectively, in ROS and THY compared to the control. Until 6h of heating, the ROS kept the greatest oxidative stability. The use of the two extracts preserves approximately 50% of the total tocopherols content until 18h for the rosemary and 24h for the thyme flavored oils. Volatile compounds known for their antioxidant activity were also detected in the formulated oils. Aromatic plants added to the soybean oil improved the overall acceptability of potato crisps (p<0.05) until the fifteenth frying. Copyright © 2016 Elsevier Ltd. All rights reserved.

  3. Nitrous Oxide Production by Abundant Benthic Macrofauna

    DEFF Research Database (Denmark)

    Stief, Peter; Schramm, Andreas

    of the short-term metabolic induction of gut denitrification is the preferential production of nitrous oxide rather than dinitrogen. On a large scale, gut denitrification in, for instance, Chironomus plumosus larvae can increase the overall nitrous oxide emission of lake sediment by a factor of eight. We...... screened more than 20 macrofauna species for nitrous oxide production and identified filter-feeders and deposit-feeders that occur ubiquitously and at high abundance (e.g., chironomids, ephemeropterans, snails, and mussels) as the most important emitters of nitrous oxide. In contrast, predatory species...... that do not ingest large quantities of microorganisms produced insignificant amounts of nitrous oxide. Ephemera danica, a very abundant mayfly larva, was monitored monthly in a nitrate-polluted stream. Nitrous oxide production by this filter-feeder was highly dependent on nitrate availability...

  4. Metabolic Engineering of the Shikimate Pathway for Production of Aromatics and Derived Compounds—Present and Future Strain Construction Strategies

    Directory of Open Access Journals (Sweden)

    Nils J. H. Averesch

    2018-03-01

    Full Text Available The aromatic nature of shikimate pathway intermediates gives rise to a wealth of potential bio-replacements for commonly fossil fuel-derived aromatics, as well as naturally produced secondary metabolites. Through metabolic engineering, the abundance of certain intermediates may be increased, while draining flux from other branches off the pathway. Often targets for genetic engineering lie beyond the shikimate pathway, altering flux deep in central metabolism. This has been extensively used to develop microbial production systems for a variety of compounds valuable in chemical industry, including aromatic and non-aromatic acids like muconic acid, para-hydroxybenzoic acid, and para-coumaric acid, as well as aminobenzoic acids and aromatic α-amino acids. Further, many natural products and secondary metabolites that are valuable in food- and pharma-industry are formed outgoing from shikimate pathway intermediates. (Reconstruction of such routes has been shown by de novo production of resveratrol, reticuline, opioids, and vanillin. In this review, strain construction strategies are compared across organisms and put into perspective with requirements by industry for commercial viability. Focus is put on enhancing flux to and through shikimate pathway, and engineering strategies are assessed in order to provide a guideline for future optimizations.

  5. Hydrodeoxygenation of aliphatic and aromatic oxygenates on sulphided catalysts for production of second generation biofuels

    Energy Technology Data Exchange (ETDEWEB)

    Senol, O.I.

    2007-07-01

    Environmental concerns and diminishing petroleum reserves have increased the importance of biofuels for traffic fuel applications. Second generation biofuels produced from wood, vegetable oils and animal fats have been considered promising for delivering biofuels in large amount with low production cost. The abundance of oxygen in the form of various aliphatic and aromatic oxygenates decreases the quality of biofuels, however, and therefore the oxygen content of biofuels must be reduced. Upgrading of biofuels can be achieved by hydrodeoxygenation (HDO), which is similar to hydrodesulphurisation in oil refining. In HDO, oxygen-containing compounds are converted to hydrocarbons by eliminating oxygen in the form of water in the presence of hydrogen and a sulphided catalyst. Due to the low sulphur content of biofuels, a sulphiding agent is typically added to the HDO feed to maintain activity and stability of the catalyst. The aim of this work was to investigate HDO using aliphatic and aromatic oxygenates as model compounds on sulphided NiMo/gamma-Al{sub 2}O3 and CoMo/gamma-Al{sub 2}O3 catalysts. The effects of side product, water, and of sulphiding agents, H{sub 2}S and CS{sub 2}, on HDO were determined. The primary focus was on the HDO of aliphatic oxygenates, because a reasonable amount of data regarding the HDO of aromatic oxygenates already exists. The HDO of aliphatic esters produced hydrocarbons from intermediate alcohol, carboxylic acid, aldehyde and ether compounds. A few sulphur-containing compounds were also detected in trace amounts, and their formation caused desulphurisation of the catalysts. Hydrogenation reactions and acid-catalysed reactions (dehydration, hydrolysis, esterification, E{sub 2} elimination and SN{sub 2} nucleophilic substitution) played a major role in the HDO of aliphatic oxygenates. The NiMo catalyst showed a higher activity for HDO and hydrogenation reactions than the CoMo catalyst, but both catalysts became deactivated because of

  6. Hemoglobin binding of aromatic amines: molecular dosimetry and quantitative structure-activity relationships for N-oxidation.

    Science.gov (United States)

    Sabbioni, G

    1993-01-01

    Aromatic amines are important intermediates in industrial manufacturing. N-Oxidation to N-hydroxyarylamines is a key step in determining the genotoxic properties of aromatic amines. N-Hydroxyarylamines can form adducts with DNA, with tissue proteins, and with the blood proteins albumin and hemoglobin in a dose-dependent manner. The determination of hemoglobin adducts is a useful tool for biomonitoring exposed populations. We have established the hemoglobin binding index (HBI) [(mmole compound/mole hemoglobin)/(mmole compound/kg body weight)] of several aromatic amines in female Wistar rats. Including the values from other researchers obtained in the same rat strain, the logarithm of hemoglobin binding (logHBI) was plotted against the following parameters: the sum of the Hammett constants(sigma sigma = sigma p + sigma m), pKa, logP (octanol/water), the half-wave oxidation potential (E1/2), and the electronic descriptors of the amines and their corresponding nitrenium ions obtained by semi-empirical calculations (MNDO, AMI, and PM3), such as atomic charge densities, energies of the highest occupied molecular orbit and lowest occupied molecular orbit and their coefficients, the bond order of C-N, the dipole moments, and the reaction enthalpy [MNDOHF, AM1HF or PM3HF = Hf(nitrenium) - Hf(amine)]. The correlation coefficients were determined from the plots of all parameters against log HBI for all amines by means of linear regression analysis. The amines were classified in three groups: group 1, all parasubstituted amines (maximum, n = 9); group 2, all amines with halogens (maximun, n = 11); and group 3, all amines with alkyl groups (maximum, n = 13).(ABSTRACT TRUNCATED AT 250 WORDS) PMID:8319626

  7. Formation of polycyclic aromatic hydrocarbons and soot in fuel-rich oxidation of methane in a laminar flow reactor

    DEFF Research Database (Denmark)

    Skjøth-Rasmussen, Martin Skov; Glarborg, Peter; Østberg, M.

    2004-01-01

    Conversion of methane to higher hydrocarbons, polycyclic aromatic hydrocarbons (PAHs), and soot was investigated under fuel-rich conditions in a laminar flow reactor. The effects of stoichiometry, dilution, and water vapor addition were studied at temperatures between 1073 and 1823 K. A chemical...... kinetic mechanism was established for methane oxidation, with emphasis on formation of higher hydrocarbons and PAH. A submodel for soot formation was adopted from the work of Frenklach and co-workers without changes. Modeling predictions showed good agreement with experimental results. Reactants, stable...... decrease with increasing addition of water vapor. The effect is described qualitatively by the reaction mechanism. The enhanced oxidation of acetylene is attributed to higher levels of hydroxyl radicals, formed from the reaction between the water vapor and hydrogen atoms....

  8. Induced production of brominated aromatic compounds in the alga Ceramium tenuicorne.

    Science.gov (United States)

    Dahlgren, Elin; Enhus, Carolina; Lindqvist, Dennis; Eklund, Britta; Asplund, Lillemor

    2015-11-01

    In the Baltic Sea, high concentrations of toxic brominated aromatic compounds have been detected in all compartments of the marine food web. A growing body of evidence points towards filamentous algae as a natural producer of these chemicals. However, little is known about the effects of environmental factors and life history on algal production of brominated compounds. In this study, several congeners of methoxylated polybrominated diphenyl ethers (MeO-PBDEs), hydroxylated polybrominated diphenyl ethers (OH-PBDEs) and brominated phenols (BPs) were identified in a naturally growing filamentous red algal species (Ceramium tenuicorne) in the Baltic Sea. The identified substances displayed large seasonal variations in the alga with a concentration peak in July. Production of MeO-/OH-PBDEs and BPs by C. tenuicorne was also established in isolated clonal material grown in a controlled laboratory setting. Based on three replicates, herbivory, as well as elevated levels of light and salinity in the culture medium, significantly increased the production of 2,4,6-tribromophenol (2,4,6-TBP). Investigation of differences in production between the isomorphic female, male and diploid clonal life stages of the alga grown in the laboratory revealed a significantly higher production of 2,4,6-TBP in the brackish water female gametophytes, compared to the corresponding marine gametophytes. Even higher concentrations of 2,4,6-TBP were produced by marine male gametophytes and sporophytes.

  9. Influence of processing in the prevalence of polycyclic aromatic hydrocarbons in a Portuguese traditional meat product.

    Science.gov (United States)

    Roseiro, L C; Gomes, A; Santos, C

    2011-06-01

    The concentration of 16 polycyclic aromatic hydrocarbons (PAHs) was determined in traditional dry/fermented sausage along distinct stages of processing under two different technological procedures (traditional and modified processes). The influence of product's position in the smoking room, on the variation of contaminants and in their migration dynamics from the outer into the inner part, was also followed up. Raw material mixtures presented expressive total PAH values, 106.17 μg kg(-1) in wet samples and 244.34 μg kg(-1) in dry mater (DM), expressing the frequent fire woods occurred in the regions pigs were extensively reared. Traditional processing produced a higher (plevels comparatively to modified/industrial procedures, with mean values reaching 3237.10 and 1702.85 μg kg(-1) DM, respectively. Both, raw materials and final products, showed PAH profiles with light compounds representing about 99.0% of the total PAHs, mostly accounted by those having two rings (naphthalene-27.5%) or three rings (acenaphtene-16.9%; fluorene-27.1%; phenanthrene-19.5% and anthracene-3.9%). The benzo[a]pyrene (BaP) accumulated in traditional and modified processed products never surpassed the limit of 5 μg kg(-1) established by the EU legislation. PAHs in products hanged in bars closer to heating/smoking source speed up their transfer from the surface/outer portion to the inner part of the product. Copyright © 2011 Elsevier Ltd. All rights reserved.

  10. Practical applications of the Fenton reaction to the removal of chlorinated aromatic pollutants. Oxidative degradation of 2,4-dichlorophenol.

    Science.gov (United States)

    Detomaso, Antonia; Lopez, Antonio; Lovecchio, Giangiuseppe; Mascolo, Giuseppe; Curci, Ruggero

    2003-01-01

    Chlorophenols (CPs) constitute a group of organic pollutants that are introduced into the environment as a result of several man-made activities, such as uncontrolled use of pesticides and herbicides, and as byproducts in the paper pulp bleaching. Promising removal technologies of chlorinated aromatics consist in the application of advanced oxidation processes (AOPs) that can provide an almost total degradation of a variety of contaminants. Among these, wide application find Fenton systems based on generation of reactive species having a high oxidizing power, such as hydroxyl radical HO*. Our objective was that of determining the overall degradation efficiency of the model compound 2,4-dichlorophenol (DCP) by thermal Fenton-type oxidation systems with a view toward defining in more details relevant process parameters, the effect of reaction temperature and of co-catalyst Cu2+. Reaction conditions were similar to those generally adopted as optimal in many practical applications, i.e. pollutant/Fe2+ (as FeSO4) ratio ca. 20, Fe2+/Cu2+ (co-catalyst) 2:1, pH adjusted and controlled at pH 3, and H2O2 in excess (up to four-fold over the stoichiometric amount required for complete mineralization). The results demonstrate that it is advantageous to carry out the reaction at a temperature markedly higher (70 degrees C) than ambient. The stepwise addition of H2O2 in aliquots yields an efficient transformation, while allowing a convenient control of the reaction exothermicity. Under these conditions, the essentially complete removal of the initial DCP is accomplished using just one equiv of H2O2 during 15 min; excess H2O2 (5 equivalents) yields extensive substrate mineralization. Also relevant, at 70 degrees C dechlorination of the initial DCP (and of derived reaction intermediates) is remarkably extensive (3-5% residual TOX), already with the addition of 1 equiv of H2O2. At the end of the reaction, IC and IC-MS analyses of the solution reveal that only low-molecular weight

  11. Oxide production program monthly report - December 2014

    Energy Technology Data Exchange (ETDEWEB)

    Kelley, Evelyn A. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Whitworth, Julia [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Lloyd, Jane Alexandria [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Hampton, David Earl [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Benavidez, Amelia A. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2015-01-15

    A summary of the major activities, accomplishments, milestones, financial summary, project performance and issues facing the ARIES Oxide Production Program for the month of December 2014 is presented in this Executive Summary.

  12. Recent advances in Phytosterol Oxidation Products.

    Science.gov (United States)

    O'Callaghan, Yvonne; McCarthy, Florence O; O'Brien, Nora M

    2014-04-11

    Phytosterols and their oxidation products have become increasingly investigated in recent years with respect to their roles in diet and nutrition. We present a comprehensive review of recent literature on Phytosterol Oxidation Products (POP) identifying critical areas for future investigation. It is evident that POP are formed on food storage/preparation; are absorbed and found in human serum; do not directly affect cholesterol absorption; have evidence of atherogenicity and inflammation; have distinct levels of cytotoxicity; are implicated with high levels of oxidative stress, glutathione depletion, mitochondrial dysfunction and elevated caspase activity. Copyright © 2014 Elsevier Inc. All rights reserved.

  13. Photoinduced oxidation of sea salt halides by aromatic ketones: a source of halogenated radicals

    Directory of Open Access Journals (Sweden)

    A. Jammoul

    2009-07-01

    Full Text Available The interactions between triplet state benzophenone and halide anion species (Cl, Br and I have been studied by laser flash photolysis (at 355 nm in aqueous solutions at room temperature. The decay of the triplet state of benzophenone was followed at 525 nm. Triplet lifetime measurements gave rate constants, kq (M−1 s, close to diffusion controlled limit for iodide (~8×109 M−1 s, somewhat less for bromide (~3×108 M−1 s and much lower for chloride (<106 M−1 s. The halide (X quenches the triplet state; the resulting product has a transient absorption at 355 nm and a lifetime much longer than that of the benzophenone triplet state, is formed. This transient absorption feature matches those of the corresponding radical anion (X2. We therefore suggest that such reactive quenching is a photosensitized source of halogen in the atmosphere or the driving force for the chemical oxidation of the oceanic surface micro layer.

  14. Oriented Decoration in Metal-Functionalized Ordered Mesoporous Silicas and Their Catalytic Applications in the Oxidation of Aromatic Compounds

    Directory of Open Access Journals (Sweden)

    Shijian Zhou

    2018-02-01

    Full Text Available Ordered mesoporous silicas (OMSs attract considerable attention due to their advanced structural properties. However, for the pristine silica materials, the inert property greatly inhibits their catalytic applications. Thus, to contribute to the versatile surface of OMSs, different metal active sites, including acidic/basic sites and redox sites, have been introduced into specific locations (mesoporous channels and framework of OMSs and the metal-functionalized ordered mesoporous silicas (MOMSs show great potential in the catalytic applications. In this review, we first present the categories of metal active sites. Then, the synthesized processes of MOMSs are thoroughly discussed, in which the metal active sites would be introduced with the assistance of organic groups into the specific locations of OMSs. In addition, the structural morphologies of OMSs are elaborated and the catalytic applications of MOMSs in the oxidation of aromatic compounds are illustrated in detail. Finally, the prospects for the future development in this field are proposed.

  15. Escherichia coli as a potential hydrocarbon conversion microorganism. Oxidation of aliphatic and aromatic compounds by recombinant E. coli in two-liquid phase (aqueous-organic) systems

    NARCIS (Netherlands)

    Favre-Bulle, Olivier

    1992-01-01

    The increased interest in the study of hydrocarbon utilizing microorganisms in recent years has been stimulated by the possibility of using their monooxygenases in the selective oxidation of aliphatic and aromatic compounds. As an example, long chain (>C16) n-alkanes are converted to dicarboxylic

  16. Photocatalytic organic transformation by layered double hydroxides: highly efficient and selective oxidation of primary aromatic amines to their imines under ambient aerobic conditions.

    Science.gov (United States)

    Yang, Xiu-Jie; Chen, Bin; Li, Xu-Bing; Zheng, Li-Qiang; Wu, Li-Zhu; Tung, Chen-Ho

    2014-06-25

    We report the first application of layered double hydroxide as a photocatalyst in the transformation of primary aromatic amines to their corresponding imines with high efficiency and selectivity by using oxygen in an air atmosphere as a terminal oxidant under light irradiation.

  17. Cu(OAc)2/TFA-promoted formal [3 + 3] cycloaddition/oxidation of enamines and enones for synthesis of multisubstituted aromatic amines.

    Science.gov (United States)

    Li, Liang; Zhao, Mi-Na; Ren, Zhi-Hui; Li, Jian-Li; Guan, Zheng-Hui

    2012-07-06

    New strategies for the oxidative cycloaddition of enones with enamines are developed. These cycloaddition reactions directly afford substituted aromatic amines, which are important in organic chemistry, in moderate to good yield. Cu(OAc)(2)/TFA is shown to be essential to achieve high reaction efficiency.

  18. Cathode recovery products of oxidation of oils

    Directory of Open Access Journals (Sweden)

    М.М. Захарчук

    2009-01-01

    Full Text Available  The article provides the review of electrochemical reduction of carbonic compounds – those that are among main oxidation of oils  hydrocarbons products. The principal possibility of ketons to alcohols  reduction is proved in practice based on the experimental data . The methodical algoritm of quantative control of the catod reduction is developed, which uses the reduction-oxidizing potentiometric titration method.

  19. Determination of aromatic fragment content in phenol-containing fractions of solid fuel conversion products using nuclear magnetic resonance spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Kanitskaya, L.V.; Kushnarev, D.F.; Polonov, V.M.; Kalabin, G.A.

    1986-03-01

    Optimum conditions are determined for obtaining quantitative nuclear magnetic resonance /sup 13/C spectra of fragments in phenol-containing fraction of coal products. Causes are analyzed of residual signals in spectra of un-protonized carbon atoms. The tests were carried out on: low-temperature carbonization tar and phenol fraction obtained during medium-temperature coking of Cherenkhovskii coal (which contains 84.13% C; 9.68% H; 1.23% S; 4.96% O); products of tar hydrogenation with various phenol content; standard phenol mixture. It was found that quantitative determination of aromatic fraction content in coal conversion products and other phenol- and amine-containing complex mixtures, using NMR spectroscopy requires the addition of dimethylsulfide or acetone in order to suppress specific interactions of phenols (amines) with relaxants and obtain quantitative subspectra of Tertiary and Quaternary aromatic carbon atoms. 16 references.

  20. Chain radiation-chemical oxidation of aromatic amines in polyvinylchloride films

    International Nuclear Information System (INIS)

    Kolninov, O.V.; Lisovskaya, I.A.; Milinchuk, V.K.

    1983-01-01

    Radiation-chemical oxidation of tetramethyldiaminediphenylmethane in polyvinylchloride (PVC) and polystyrene (PS) films was investigated in the presence of CBr 4 at 300 K. Radiation yields (G) of 70 and 1 were obtained for an oxidized amine form (Am + ) in PVC and PS, resp. High yields of Am + in PVC matrix indicate the chain character of an oxidation reaction. Triplet states, which form exciplexes with CBr 4 were established to participate in oxidation reactions. The kinetic scheme suggested for the chain radiation oxidation of Am takes into account energy transfer, formation and degradation of the excited states of molecules resulting in the initiation and propagation of the chain on the account of active particles. (author)

  1. Carbon dioxide hydrogenation to aromatic hydrocarbons by using an iron/iron oxide nanocatalyst

    Directory of Open Access Journals (Sweden)

    Hongwang Wang

    2014-06-01

    Full Text Available The quest for renewable and cleaner energy sources to meet the rapid population and economic growth is more urgent than ever before. Being the most abundant carbon source in the atmosphere of Earth, CO2 can be used as an inexpensive C1 building block in the synthesis of aromatic fuels for internal combustion engines. We designed a process capable of synthesizing benzene, toluene, xylenes and mesitylene from CO2 and H2 at modest temperatures (T = 380 to 540 °C employing Fe/Fe3O4 nanoparticles as catalyst. The synthesis of the catalyst and the mechanism of CO2-hydrogenation will be discussed, as well as further applications of Fe/Fe3O4 nanoparticles in catalysis.

  2. Hydrogen sulfide oxidation without oxygen - oxidation products and pathways

    International Nuclear Information System (INIS)

    Fossing, H.

    1992-01-01

    Hydrogen sulfide oxidation was studied in anoxic marine sediments-both in undisturbed sediment cores and in sediment slurries. The turn over of hydrogen sulfide was followed using 35 S-radiolabeled hydrogen sulfide which was injected into the sediment. However, isotope exchange reactions between the reduced sulfur compounds, in particular between elemental sulfur and hydrogen sulfide, influenced on the specific radioactivity of these pools. It was, therefore, not possible to measure the turn over rates of the reduced sulfur pools by the radiotracer technique but merely to use the radioisotope to demonstrate some of the oxidation products. Thiosulfate was one important intermediate in the anoxic oxidation of hydrogen sulfide and was continuously turned over by reduction, oxidation and disproportionation. The author discusses the importance of isotope exchange and also presents the results from experiments in which both 35 S-radiolabeled elemental sulfur, radiolabeled hydrogen sulfide and radiolabeled thiosulfate were used to study the intermediates in the oxidative pathways of the sulfur cycle

  3. Production of oceanic nitrous oxide by ammonia-oxidizing archaea

    Directory of Open Access Journals (Sweden)

    C. R. Löscher

    2012-07-01

    Full Text Available The recent finding that microbial ammonia oxidation in the ocean is performed by archaea to a greater extent than by bacteria has drastically changed the view on oceanic nitrification. The numerical dominance of archaeal ammonia-oxidizers (AOA over their bacterial counterparts (AOB in large parts of the ocean leads to the hypothesis that AOA rather than AOB could be the key organisms for the oceanic production of the strong greenhouse gas nitrous oxide (N2O that occurs as a by-product of nitrification. Very recently, enrichment cultures of marine ammonia-oxidizing archaea have been reported to produce N2O.

    Here, we demonstrate that archaeal ammonia monooxygenase genes (amoA were detectable throughout the water column of the eastern tropical North Atlantic (ETNA and eastern tropical South Pacific (ETSP Oceans. Particularly in the ETNA, comparable patterns of abundance and expression of archaeal amoA genes and N2O co-occurred in the oxygen minimum, whereas the abundances of bacterial amoA genes were negligible. Moreover, selective inhibition of archaea in seawater incubations from the ETNA decreased the N2O production significantly. In studies with the only cultivated marine archaeal ammonia-oxidizer Nitrosopumilus maritimus SCM1, we provide the first direct evidence for N2O production in a pure culture of AOA, excluding the involvement of other microorganisms as possibly present in enrichments. N. maritimus showed high N2O production rates under low oxygen concentrations comparable to concentrations existing in the oxycline of the ETNA, whereas the N2O production from two AOB cultures was comparably low under similar conditions. Based on our findings, we hypothesize that the production of N2O in tropical ocean areas results mainly from archaeal nitrification and will be affected by the predicted decrease in dissolved

  4. Selective aerobic alcohol oxidation method for conversion of lignin into simple aromatic compounds

    Science.gov (United States)

    Stahl, Shannon S; Rahimi, Alireza

    2015-03-03

    Described is a method to oxidize lignin or lignin sub-units. The method includes oxidation of secondary benzylic alcohol in the lignin or lignin sub-unit to a corresponding ketone in the presence of unprotected primarily aliphatic alcohol in the lignin or lignin sub-unit. The optimal catalyst system consists of HNO.sub.3 in combination with another Bronsted acid, in the absence of a metal-containing catalyst, thereby yielding a selectively oxidized lignin or lignin sub-unit. The method may be carried out in the presence or absence of additional reagents including TEMPO and TEMPO derivatives.

  5. Co-oxidation of carcinogenic polycyclic aromatic hydrocarbons with some biologically active compounds (BAC)

    Energy Technology Data Exchange (ETDEWEB)

    Gubergrits, M.Y.

    1978-09-01

    Oxidation of benzo(a)pyrene (BP) initiated by UV or gamma irradiation was promoted by benz(a)anthracene and 7,12-dimethylbenz(a)anthracene (DMBA) and inhibited by pyrene, dibenz(a,c)anthracene, and asymmetric benz(a)antharacene. The effects of these BAC commonly occurring together with BP in industrial wastes, increased with their concentrations. Phenol and 3-methylcholanthrene strongly promoted BP oxidation when present at low concentrations and inhibited it at high concentrations. Consistent promoting effect was also observed in BP co-oxidation with adipic acid, ..cap alpha..-naphthoflavon, and vitamin E, whereas succinic, azelaic, ferulic, gallic, and chlorogenic acids, rutin, and vitamin C acted as inhibitors. Most saturated dicarboxylic acids studied did not affect BP oxidation at 1:1 acid-BP molar ratio. The kinetics of 7,12-DMBA photooxidation inhibition by some metabolic intermediates, e.g., DMBA endo-peroxide, were also studied.

  6. Emission characteristics and size distribution of polycyclic aromatic hydrocarbons from coke production in China

    Science.gov (United States)

    Mu, Ling; Peng, Lin; Liu, Xiaofeng; He, Qiusheng; Bai, Huiling; Yan, Yulong; Li, Yinghui

    2017-11-01

    Coking is regarded as a major source of atmospheric polycyclic aromatic hydrocarbons (PAHs), but few researches have been conducted on the emission characteristics of PAHs from coke production. In this study, emissions of size-segregated particulate matter (PM) and particle-bound PAHs emitted from charging of coal (CC) and pushing of coke (PC) in four typical coke plants were determined. The emission factors on average, sums of CC and PC, were 4.65 mg/kg, 5.96 mg/kg, 19.18 μg/kg and 20.69 μg/kg of coal charged for PM2.1 (≤ 2.1 μm), PM, PAHs in PM2.1 and total-PAHs, respectively. PM and PAHs emission from plants using stamp charging were significantly more than those using top charging. The profile of PAHs in PM with size ≤ 1.4 μm (PM1.4) emitted from CC process were similar with that from PC, however, it revealed obviously different tendency for PAHs in PM with size > 1.4 μm, indicating the different formation mechanism for coarse particles emitted from CC and PC. Size distributions of PM and PAHs indicated that they were primarily connected with PM1.4, and the contributions of PM1.4 to PM and PAHs emitted from the plants using stamp charging were higher than those using top charging. Some improved technology in air-pollution control devices should be considered in coke production in future based on the considerable impacts of PM1.4 and PAHs on human health and ambient air quality.

  7. Production of superconducting ceramic oxides by coprecipitation

    International Nuclear Information System (INIS)

    Bizaio, L.R.; Lima, M.A.F. de; Figueiredo Jardim, R.de; Pinheiro, E.A.; Galembeck, F.

    1988-01-01

    An alternative method for production of ceramic oxides is described. The method consist in the coprecipitation reaction of metallic ions with oxalic acid. The obtainment samples present additional phases characterized by X-rays and optical microscopy. (C.G.C.) [pt

  8. On the oxidation of the three-dimensional aromatics [B(12)X(12)](2-) (X=F, Cl, Br, I).

    Science.gov (United States)

    Boeré, René T; Derendorf, Janis; Jenne, Carsten; Kacprzak, Sylwia; Kessler, Mathias; Riebau, Rainer; Riedel, Sebastian; Roemmele, Tracey L; Rühle, Monika; Scherer, Harald; Vent-Schmidt, Thomas; Warneke, Jonas; Weber, Stefan

    2014-04-07

    The perhalogenated closo-dodecaborate dianions [B12 X12 ](2-) (X=H, F, Cl, Br, I) are three-dimensional counterparts to the two-dimensional aromatics C6 X6 (X=H, F, Cl, Br, I). Whereas oxidation of the parent compounds [B12 H12 ](2-) and benzene does not lead to isolable radicals, the perhalogenated analogues can be oxidized by chemical or electrochemical methods to give stable radicals. The chemical oxidation of the closo-dodecaborate dianions [B12 X12 ](2-) with the strong oxidizer AsF5 in liquid sulfur dioxide (lSO2 ) yielded the corresponding radical anions [B12 X12 ](⋅-) (X=F, Cl, Br). The presence of radical ions was proven by EPR and UV/Vis spectroscopy and supported by quantum chemical calculations. Use of an excess amount of the oxidizing agent allowed the synthesis of the neutral perhalogenated hypercloso-boranes B12 X12 (X=Cl, Br). These compounds were characterized by single-crystal X-ray diffraction of dark blue B12 Cl12 and [Na(SO2 )6 ][B12 Br12 ]⋅B12 Br12 . Sublimation of the crude reaction products that contained B12 X12 (X=Cl, Br) resulted in pure dark blue B12 Cl12 or decomposition to red B9 Br9 , respectively. The energetics of the oxidation processes in the gas phase were calculated by DFT methods at the PBE0/def2-TZVPP level of theory. They revealed the trend of increasing ionization potentials of the [B12 X12 ](2-) dianions by going from fluorine to bromine as halogen substituent. The oxidation of all [B12 X12 ](2-) dianions was also studied in the gas phase by mass spectrometry in an ion trap. The electrochemical oxidation of the closo-dodecaborate dianions [B12 X12 ](2-) (X=F, Cl, Br, I) by cyclic and Osteryoung square-wave voltammetry in liquid sulfur dioxide or acetonitrile showed very good agreement with quantum chemical calculations in the gas phase. For [B12 X12 ](2-) (X=F, Cl, Br) the first and second oxidation processes are detected. Whereas the first process is quasi-reversible (with oxidation potentials in the range between +1

  9. Graphene oxide and H2 production from bioelectrochemical graphite oxidation.

    Science.gov (United States)

    Lu, Lu; Zeng, Cuiping; Wang, Luda; Yin, Xiaobo; Jin, Song; Lu, Anhuai; Jason Ren, Zhiyong

    2015-11-17

    Graphene oxide (GO) is an emerging material for energy and environmental applications, but it has been primarily produced using chemical processes involving high energy consumption and hazardous chemicals. In this study, we reported a new bioelectrochemical method to produce GO from graphite under ambient conditions without chemical amendments, value-added organic compounds and high rate H2 were also produced. Compared with abiotic electrochemical electrolysis control, the microbial assisted graphite oxidation produced high rate of graphite oxide and graphene oxide (BEGO) sheets, CO2, and current at lower applied voltage. The resultant electrons are transferred to a biocathode, where H2 and organic compounds are produced by microbial reduction of protons and CO2, respectively, a process known as microbial electrosynthesis (MES). Pseudomonas is the dominant population on the anode, while abundant anaerobic solvent-producing bacteria Clostridium carboxidivorans is likely responsible for electrosynthesis on the cathode. Oxygen production through water electrolysis was not detected on the anode due to the presence of facultative and aerobic bacteria as O2 sinkers. This new method provides a sustainable route for producing graphene materials and renewable H2 at low cost, and it may stimulate a new area of research in MES.

  10. Smoking modify the effects of polycyclic aromatic hydrocarbons exposure on oxidative damage to DNA in coke oven workers.

    Science.gov (United States)

    Yang, Jin; Zhang, Hongjie; Zhang, Huitao; Wang, Wubin; Liu, Yanli; Fan, Yanfeng

    2017-07-01

    Coke oven emissions containing polycyclic aromatic hydrocarbons (PAHs) are predominant toxic constituents of particulate air pollution that have been linked to increased risk of lung cancer. Numerous epidemiological studies have suggested that oxidative DNA damage may play a pivotal role in the carcinogenic mechanism of lung cancer. Little is known about the effect of interaction between PAHs exposure and lifestyle on DNA oxidative damage. The study population is composed by coke oven workers (365) and water treatment workers (144), and their urinary levels of four PAH metabolites and 8-hydroxydeoxyguanosine (8-OHdG) were determined. Airborne samples of exposed sites (4) and control sites (3) were collected, and eight carcinogenic PAHs were detected by high-performance liquid chromatography. The median values of the sum of eight carcinogenic PAHs and BaP in exposed sites were significantly higher than control sites (P < 0.01). The study found that the urinary PAH metabolites were significantly elevated in coke oven workers (P < 0.01). Multivariate logistic regression analysis revealed that the risk of high levels of urinary 8-OHdG will increase with increasing age, cigarette consumption, and levels of urinary 1-hydroxypyrene, and P for trend were all <0.05. Smoking can significantly modify the effects of urinary 1-hydroxypyrene on high concentrations urinary 8-OHdG, during co-exposure to both light or heavy smoking and high 1-hydroxypyrene levels (OR 4.28, 95% CI 1.32-13.86 and OR 5.05, 95% CI 1.63-15.67, respectively). Our findings quantitatively demonstrate that workers exposed to coke oven fumes and smoking will cause more serious DNA oxidative damage.

  11. Efficient Method for Aromatic-Aldehyde Oxidation by Cleavage of Their Hydrazones Catalysed by Trimethylsilanolate

    Czech Academy of Sciences Publication Activity Database

    Bürglová, K.; Okorochenkov, S.; Buděšínský, Miloš; Hlaváč, J.

    2017-01-01

    Roč. 2017, č. 2 (2017), s. 389-396 ISSN 1434-193X R&D Projects: GA MŠk(CZ) LO1304 Institutional support: RVO:61388963 Keywords : aldehydes * oxidation * hydrazones * solid-phase synthesis * reaction mechanisms Subject RIV: CC - Organic Chemistry OBOR OECD: Organic chemistry Impact factor: 2.834, year: 2016

  12. Formation of chemical compounds from irradiated mixtures of aromatic hydrocarbons and nitrogen oxides

    NARCIS (Netherlands)

    Besemer, A.C.

    1982-01-01

    The paper describes the analysis of products of the photochemical degradation of toluene and toluene-14C in smog chamber experiments. Compounds identified included methylglyoxal, possibly the recently postulated butenedial and other carbonyl compounds. The main product of photochemical degradation

  13. Formation of chemical compounds from irradiated mixtures of aromatic hydrocarbons and nitrogen oxides

    International Nuclear Information System (INIS)

    Besemer, A.C.

    1982-01-01

    The analysis of products of the photochemical degradation of toluene and toluene- 14 C in smog chamber experiments is described. Compounds identified included methylglyoxal, possibly the recently postulated butenedial and other carbonyl compounds. The main product of photochemical degradation of methylglyoxal appeared to be acetaldehyde. (author)

  14. Graphene oxide bound silica for solid-phase extraction of 14 polycyclic aromatic hydrocarbons in mainstream cigarette smoke.

    Science.gov (United States)

    Shi, Rui; Yan, Lihong; Xu, Tongguang; Liu, Dongye; Zhu, Yongfa; Zhou, Jun

    2015-01-02

    Polycyclic aromatic hydrocarbons (PAHs) were considered as a source of carcinogenicity in mainstream cigarette smoke (MSS). Accurate quantification of these components was necessary for assessing public health risk. In our study, a solid-phase extraction (SPE) method using graphene oxide (GO) bound silica as adsorbent for purification of 14 PAHs in MSS was developed. During SPE process, large matrices interferences of MSS were adsorbed on SPE column. The result of FTIR spectra demonstrated that these matrices interferences were adsorbed on GO mainly through OH and CO groups. The concentrations of PAHs in MSS extract were determined by gas chromatography-mass spectrometry (GC-MS). The limit of detection (LOD) and limit of quantification (LOQ) of the developed method for 14 PAHs ranged from 0.05 to 0.36 ng/cig and 0.17 to 1.19 ng/cig, respectively. The accuracy of the measurement of 14 PAHs was from 73 to 116%. The relative standard deviations of intra- and inter-day analysis were less than 7.8% and 13.9%, respectively. Moreover, the developed method was successfully applied for analysis of real cigarette containing 1R5F reference cigarette and 12 top-selling commercial cigarettes in China. Copyright © 2014 Elsevier B.V. All rights reserved.

  15. Environmental exposure to polycyclic aromatic hydrocarbons, kitchen ventilation, fractional exhaled nitric oxide, and risk of diabetes among Chinese females.

    Science.gov (United States)

    Hou, J; Sun, H; Zhou, Y; Zhang, Y; Yin, W; Xu, T; Cheng, J; Chen, W; Yuan, J

    2018-05-01

    Diabetes is related to exposure to polycyclic aromatic hydrocarbons (PAHs), inflammation in the body, and housing characters. However, associations of urinary monohydroxy-PAHs (OH-PAHs) or fractional exhaled nitric oxide (FeNO) with diabetes risk in relation to housing characters are unclear. In this study, 2645 individuals were drawn from the baseline survey of the Wuhan-Zhuhai Cohort Study. Associations of diabetes with urinary OH-PAHs or FeNO among cooking participants were estimated using logistic regression models. Among women with self-cooking meals, urinary OH-PAH levels were positively associated with diabetes risk (P kitchen exhaust fans/hoods had a 52% decrease in the risk of diabetes (OR: 0.48, 95% CI: 0.27, 0.84), compared with those with nonuse of kitchen exhaust fans/hoods. The results indicated that the cooking women had an elevated risk of diabetes, which may be partly explained by an increase in the PAH body burden and higher inflammatory responses. Use of kitchen exhaust fan/hood can be associated with a lower risk of diabetes. © 2018 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

  16. Impact of Air Frying on Cholesterol and Fatty Acids Oxidation in Sardines: Protective Effects of Aromatic Herbs.

    Science.gov (United States)

    Ferreira, Fernanda S; Sampaio, Geni R; Keller, Laura M; Sawaya, Alexandra C H F; Chávez, Davy W H; Torres, Elizabeth A F S; Saldanha, Tatiana

    2017-12-01

    The high temperatures used to fry fish may induce thermo-oxidation of cholesterol, forming cholesterol oxidation products (COPs). COPs have been associated to coronary heart diseases, atherosclerosis, and other chronic diseases. Air fryers are an alternative thermal process technology to fry foods without oil, and are considered a healthier cooking method. This study is the 1st to evaluate the formation of COPs and the degradation of polyunsaturated fatty acids (PUFAs) in air-fried sardine fillets. Furthermore, we evaluated the effect of fresh herbs added as natural antioxidants to sardines subjected to air frying. Parsley (Petroselinum crispum), chives (Allium schoenoprasum L.), and a mixture of both herbs (cheiro-verde) were added in quantities of 0%, 2%, and 4%. Air frying significantly decreased the content of essential PUFAs, and increased the levels of COPs from 61.2 (raw) to 283 μg/g (P addition of 4% of cheiro-verde in air-fried sardines presented the best protective effect against lipid oxidation. Fish is an important source of essential lipids. However, oxidized cholesterol products, which are formed during thermal processing, are potential hazards to human health. Air fryers present an alternative thermal process for frying food without oil, and this method of cooking is considered to be more convenient and healthier This study shows that the air frying increased the formation of cholesterol oxidation products and decreased the essential polyunsaturated fatty acids in sardine fillets. However, the lipid oxidation is significantly reduced by adding fresh herbs, such as parsley (Petroselinum crispum), chives (Allium schoenoprasum L.), or a mixture of both herbs (cheiro-verde) that are natural antioxidants. © 2017 Institute of Food Technologists®.

  17. PhI(OAc)2-mediated one-pot oxidative decarboxylation and aromatization of tetrahydro-β-carbolines: synthesis of norharmane, harmane, eudistomin U and eudistomin I.

    Science.gov (United States)

    Kamal, Ahmed; Tangella, Yellaiah; Manasa, Kesari Lakshmi; Sathish, Manda; Srinivasulu, Vunnam; Chetna, Jadala; Alarifi, Abdullah

    2015-08-28

    Iodobenzene diacetate was employed as a mild and efficient reagent for one-pot oxidative decarboxylation of tetrahydro-β-carboline acids and dehydrogenation of tetrahydro-β-carbolines to access the corresponding aromatic β-carbolines. To the best of our knowledge this is the first synthesis of β-carbolines via a one-pot oxidative decarboxylation at ambient temperature. The utility of this protocol has been demonstrated in the synthesis of β-carboline alkaloids norharmane (2o), harmane (2p), eudistomin U (9) and eudistomin I (12).

  18. Nitrous oxide emissions of energy production

    International Nuclear Information System (INIS)

    Kinnunen, L.

    1998-01-01

    The share of energy production of the world-wide total N 2 O emissions is about 10 %. In 1991 the N 2 O emissions estimated to be up to 30 %. The previous estimates based on incorrect measurements. The measurement methods have been improved during the past few years. The present measurements have shown that the share of the combustion of fossil fuels is about 2.0 % and the share biomass combustion about 5.0 % of the total. The uncertainty of the values can be few percentage units. According to the present measurements the share of natural emissions and the fertilizers of the total N 2 O emissions is up to 60 %. The formation of nitrous oxide has been studied widely in various countries in the world. In Finland nitrous oxide has been studied in the national LIEKKI research programme. As a result of the research carried out in the programme it has been possible to reduce the formation of N 2 O by using appropriate catalysts and combustion technologies. Nitrous oxide is formed e.g. in fluidized-bed combustion of nitrogen containing fuels. The combustion temperature of other combustion methods is so high that the gas disintegrates in the furnace. By the new methods the nitrous oxide emissions of the fluidized-bed combustion has been possible to reduce from 100-200 ppm to the level less than 50 ppm of the flue gas volume. The Japanese research has shown that the nitrous oxide emissions of bubbling beds vary in between 58 - 103 ppm, but when combusting paper the emissions are 6 - 29 ppm. The corresponding value of circulating fluidized beds is 40 - 153 ppm

  19. Method for production of unsaturated gaseous hydrocarbons, particularly ethylene, and of aromatic hydrocarbons, adapted as motor fuels

    Energy Technology Data Exchange (ETDEWEB)

    1952-10-24

    A method is described for the production of unsaturated gaseous hydrocarbons, in particular of ethylene, and of aromatic hydrocarbons from hydrocarbon oils or from fractions of the same, characterized by the fact that the raw materials are brought into contact with porous, inert substances in the form of fine distribution or of pieces at a temperature of above 500 and in particular from 600 to about 700/sup 0/C and with a traversing speed of from 0.3 up to about 3.0 volumetric parts, preferably up to 1.5 volumetric parts of raw material per volumetric part of the chamber and per hour.

  20. Global oceanic production of nitrous oxide

    Science.gov (United States)

    Freing, Alina; Wallace, Douglas W. R.; Bange, Hermann W.

    2012-01-01

    We use transient time distributions calculated from tracer data together with in situ measurements of nitrous oxide (N2O) to estimate the concentration of biologically produced N2O and N2O production rates in the ocean on a global scale. Our approach to estimate the N2O production rates integrates the effects of potentially varying production and decomposition mechanisms along the transport path of a water mass. We estimate that the oceanic N2O production is dominated by nitrification with a contribution of only approximately 7 per cent by denitrification. This indicates that previously used approaches have overestimated the contribution by denitrification. Shelf areas may account for only a negligible fraction of the global production; however, estuarine sources and coastal upwelling of N2O are not taken into account in our study. The largest amount of subsurface N2O is produced in the upper 500 m of the water column. The estimated global annual subsurface N2O production ranges from 3.1 ± 0.9 to 3.4 ± 0.9 Tg N yr−1. This is in agreement with estimates of the global N2O emissions to the atmosphere and indicates that a N2O source in the mixed layer is unlikely. The potential future development of the oceanic N2O source in view of the ongoing changes of the ocean environment (deoxygenation, warming, eutrophication and acidification) is discussed. PMID:22451110

  1. Global oceanic production of nitrous oxide.

    Science.gov (United States)

    Freing, Alina; Wallace, Douglas W R; Bange, Hermann W

    2012-05-05

    We use transient time distributions calculated from tracer data together with in situ measurements of nitrous oxide (N(2)O) to estimate the concentration of biologically produced N(2)O and N(2)O production rates in the ocean on a global scale. Our approach to estimate the N(2)O production rates integrates the effects of potentially varying production and decomposition mechanisms along the transport path of a water mass. We estimate that the oceanic N(2)O production is dominated by nitrification with a contribution of only approximately 7 per cent by denitrification. This indicates that previously used approaches have overestimated the contribution by denitrification. Shelf areas may account for only a negligible fraction of the global production; however, estuarine sources and coastal upwelling of N(2)O are not taken into account in our study. The largest amount of subsurface N(2)O is produced in the upper 500 m of the water column. The estimated global annual subsurface N(2)O production ranges from 3.1 ± 0.9 to 3.4 ± 0.9 Tg N yr(-1). This is in agreement with estimates of the global N(2)O emissions to the atmosphere and indicates that a N(2)O source in the mixed layer is unlikely. The potential future development of the oceanic N(2)O source in view of the ongoing changes of the ocean environment (deoxygenation, warming, eutrophication and acidification) is discussed.

  2. Alterations in growth, oxidative damage, and metal uptake of five aromatic rice cultivars under lead toxicity.

    Science.gov (United States)

    Ashraf, Umair; Hussain, Saddam; Anjum, Shakeel Ahmad; Abbas, Farhat; Tanveer, Mohsin; Noor, Mehmood Ali; Tang, Xiangru

    2017-06-01

    Lead (Pb) affects plant growth and its related physio-biochemical functions negatively. The present study investigated the responses of five different fragrant rice cultivars viz., Meixiangzhan (MXZ-2), Xiangyaxiangzhan (XYXZ), Guixiangzhan (GXZ), Basmati-385 (B-385), and Nongxiang-18 (NX-18) to four different Pb concentrations viz., 0, 400, 800 and 1200 μM. Results depicted that Pb toxicity significantly (P rice plants; nonetheless, a significant variation was found in the sensitivity of rice cultivars to Pb toxicity. Soluble sugars increased significantly only at 1200 μM in GXZ and 800 μM in B-385, whilst the maximum reductions in protein contents were observed at 1200 μM Pb for all rice cultivars. Proline contents were reduced for XYXZ and NX-18 at Pb1200 μM. Activities of superoxide dismutase (SOD), peroxidase (POD), catalase (CAT) and ascorbate peroxidase (APX) as well as reduced glutathione (GSH) and oxidized glutathione (GSSG) showed differential behavior among Pb treatments and rice cultivars. Among rice cultivars, GXZ showed better antioxidative defense system under Pb toxicity compared with all other cultivars. For all rice cultivars, the trend for Pb accumulation was recorded as: roots > stems > leaves. Furthermore, significant but negative correlations among Pb uptake and plant height (r = -0.79), tillers per plant (r = -0.91) and plant dry biomass (r = -0.81) were recorded for all rice cultivars whereas the values of translocation factor (TF) from stems to leaves were higher than roots to stems. In sum, Pb reduced the early growth and caused physio-biochemical changes in all rice cultivars, nonetheless, GXZ proved better able to tolerate Pb stress than all other rice cultivars under study. Copyright © 2017 Elsevier Masson SAS. All rights reserved.

  3. Effects of aromatic compounds on the production of bacterial nanocellulose by Gluconacetobacter xylinus.

    Science.gov (United States)

    Zhang, Shuo; Winestrand, Sandra; Guo, Xiang; Chen, Lin; Hong, Feng; Jönsson, Leif J

    2014-04-30

    Bacterial cellulose (BC) is a polymeric nanostructured fibrillar network produced by certain microorganisms, principally Gluconacetobacter xylinus. BC has a great potential of application in many fields. Lignocellulosic biomass has been investigated as a cost-effective feedstock for BC production through pretreatment and hydrolysis. It is well known that detoxification of lignocellulosic hydrolysates may be required to achieve efficient production of BC. Recent results suggest that phenolic compounds contribute to the inhibition of G. xylinus. However, very little is known about the effect on G. xylinus of specific lignocellulose-derived inhibitors. In this study, the inhibitory effects of four phenolic model compounds (coniferyl aldehyde, ferulic acid, vanillin and 4-hydroxybenzoic acid) on the growth of G. xylinus, the pH of the culture medium, and the production of BC were investigated in detail. The stability of the phenolics in the bacterial cultures was investigated and the main bioconversion products were identified and quantified. Coniferyl aldehyde was the most potent inhibitor, followed by vanillin, ferulic acid, and 4-hydroxybenzoic acid. There was no BC produced even with coniferyl aldehyde concentrations as low as 2 mM. Vanillin displayed a negative effect on the bacteria and when the vanillin concentration was raised to 2.5 mM the volumetric yield of BC decreased to ~40% of that obtained in control medium without inhibitors. The phenolic acids, ferulic acid and 4-hydroxybenzoic acid, showed almost no toxic effects when less than 2.5 mM. The bacterial cultures oxidized coniferyl aldehyde to ferulic acid with a yield of up to 81%. Vanillin was reduced to vanillyl alcohol with a yield of up to 80%. This is the first investigation of the effect of specific phenolics on the production of BC by G. xylinus, and is also the first demonstration of the ability of G. xylinus to convert phenolic compounds. This study gives a better understanding of how

  4. Enhancement of protocatechuate decarboxylase activity for the effective production of muconate from lignin-related aromatic compounds.

    Science.gov (United States)

    Sonoki, Tomonori; Morooka, Miyuki; Sakamoto, Kimitoshi; Otsuka, Yuichiro; Nakamura, Masaya; Jellison, Jody; Goodell, Barry

    2014-12-20

    The decarboxylation reaction of protocatechuate has been described as a bottleneck and a rate-limiting step in cis,cis-muconate (ccMA) bioproduction from renewable feedstocks such as sugar. Because sugars are already in high demand in the development of many bio-based products, our work focuses on improving protocatechuate decarboxylase (Pdc) activity and ccMA production in particular, from lignin-related aromatic compounds. We previously had transformed an Escherichia coli strain using aroY, which had been used as a protocatechuate decarboxylase encoding gene from Klebsiella pneumoniae subsp. pneumoniae A170-40, and inserted other required genes from Pseudomonas putida KT2440, to allow the production of ccMA from vanillin. This recombinant strain produced ccMA from vanillin, however the Pdc reaction step remained a bottleneck during incubation. In the current study, we identify a way to increase protocatechuate decarboxylase activity in E. coli through enzyme production involving both aroY and kpdB; the latter which encodes for the B subunit of 4-hydroxybenzoate decarboxylase. This permits expression of Pdc activity at a level approximately 14-fold greater than the strain with aroY only. The expression level of AroY increased, apparently as a function of the co-expression of AroY and KpdB. Our results also imply that ccMA may inhibit vanillate demethylation, a reaction step that is rate limiting for efficient ccMA production from lignin-related aromatic compounds, so even though ccMA production may be enhanced, other challenges to overcome vanilate demethylation inhibition still remain.

  5. Modeling of nitrous oxide production by autotrophic ammonia-oxidizing bacteria with multiple production pathways.

    Science.gov (United States)

    Ni, Bing-Jie; Peng, Lai; Law, Yingyu; Guo, Jianhua; Yuan, Zhiguo

    2014-04-01

    Autotrophic ammonia oxidizing bacteria (AOB) have been recognized as a major contributor to N2O production in wastewater treatment systems. However, so far N2O models have been proposed based on a single N2O production pathway by AOB, and there is still a lack of effective approach for the integration of these models. In this work, an integrated mathematical model that considers multiple production pathways is developed to describe N2O production by AOB. The pathways considered include the nitrifier denitrification pathway (N2O as the final product of AOB denitrification with NO2(-) as the terminal electron acceptor) and the hydroxylamine (NH2OH) pathway (N2O as a byproduct of incomplete oxidation of NH2OH to NO2(-)). In this model, the oxidation and reduction processes are modeled separately, with intracellular electron carriers introduced to link the two types of processes. The model is calibrated and validated using experimental data obtained with two independent nitrifying cultures. The model satisfactorily describes the N2O data from both systems. The model also predicts shifts of the dominating pathway at various dissolved oxygen (DO) and nitrite levels, consistent with previous hypotheses. This unified model is expected to enhance our ability to predict N2O production by AOB in wastewater treatment systems under varying operational conditions.

  6. Deletion of the Saccharomyces cerevisiae ARO8 gene, encoding an aromatic amino acid transaminase, enhances phenylethanol production from glucose.

    Science.gov (United States)

    Romagnoli, Gabriele; Knijnenburg, Theo A; Liti, Gianni; Louis, Edward J; Pronk, Jack T; Daran, Jean-Marc

    2015-01-01

    Phenylethanol has a characteristic rose-like aroma that makes it a popular ingredient in foods, beverages and cosmetics. Microbial production of phenylethanol currently relies on whole-cell bioconversion of phenylalanine with yeasts that harbour an Ehrlich pathway for phenylalanine catabolism. Complete biosynthesis of phenylethanol from a cheap carbon source, such as glucose, provides an economically attractive alternative for phenylalanine bioconversion. In this study, synthetic genetic array (SGA) screening was applied to identify genes involved in regulation of phenylethanol synthesis in Saccharomyces cerevisiae. The screen focused on transcriptional regulation of ARO10, which encodes the major decarboxylase involved in conversion of phenylpyruvate to phenylethanol. A deletion in ARO8, which encodes an aromatic amino acid transaminase, was found to underlie the transcriptional upregulation of ARO10 during growth, with ammonium sulphate as the sole nitrogen source. Physiological characterization revealed that the aro8Δ mutation led to substantial changes in the absolute and relative intracellular concentrations of amino acids. Moreover, deletion of ARO8 led to de novo production of phenylethanol during growth on a glucose synthetic medium with ammonium as the sole nitrogen source. The aro8Δ mutation also stimulated phenylethanol production when combined with other, previously documented, mutations that deregulate aromatic amino acid biosynthesis in S. cerevisiae. The resulting engineered S. cerevisiae strain produced >3 mm phenylethanol from glucose during growth on a simple synthetic medium. The strong impact of a transaminase deletion on intracellular amino acid concentrations opens new possibilities for yeast-based production of amino acid-derived products. Copyright © 2014 John Wiley & Sons, Ltd.

  7. Effect of oxidation on the chemical nature and distribution of low-temperature pyrolysis products from bituminous coal

    Energy Technology Data Exchange (ETDEWEB)

    Furimsky, E.; MacPhee, J.A.; Vancea, L.; Ciavaglia, L.A.; Nandi, B.N.

    1983-04-01

    Two bituminous coals, a high volatile Eastern Canadian and a medium volatile Western Canadian, were used to investigate the effect of oxidation on yields and chemical composition of gases, liquids and chars produced during coal pyrolysis. Pyrolysis experiments were performed at 500 C using the Fischer assay method. Mild oxidation of coals resulted in a decrease of liquid hydrocarbon yields. Further coal oxidation increased the proportion of aromatic carbon in liquid products as determined by N.M.R. and also increased the content of oxygen in liquid products. The content of oxygen in chars was markedly lower than in corresponding coals. An attempt is made to explain reactions occurring during oxidation and subsequent pyrolysis of coal on the basis of differences in chemical composition of gases, liquids and chars. (19 refs.)

  8. Effect of oxidation on the chemical nature and distribution of low-temperature pyrolysis products from bituminous coal

    Energy Technology Data Exchange (ETDEWEB)

    Furimsky, E.; Ciavaglia, L.A.; MacPhee, J.A.; Nandi, B.N.; Vancea, L.

    1983-04-01

    Two bituminous coals, a high volatile Eastern Canadian and a medium volatile Western Canadian, were used to investigate the effect of oxidation on yields and chemical composition of gases, liquids and chars produced during coal pyrolysis. Pyrolysis experiments were performed at 500/sup 0/C using the Fischer assay method. Mild oxidation of coals resulted in a decrease of liquid hydrocarbon yields. Further coal oxidation increased the proportion of aromatic carbon in liquid products as determined by n.m.r., and also increased the content of oxygen in liquid products. The content of oxygen in chars was markedly lower than in corresponding coals. An attempt is made to explain reactions occurring during oxidation and subsequent pyrolysis of coal on the basis of differences in chemical composition of gases, liquids and chars.

  9. Biodegradation of photo-oxidized lignite and characterization of the products

    Science.gov (United States)

    Li, Jiantao; Liu, Xiangrong; Yue, Zilin; Zhang, Yaowen

    2018-01-01

    Biodegradation of photo-oxidized Inner Mongolia lignite by pseudomonas aeruginosa was studied and the degradation percentage reached 56.27%, while the corresponding degradation percentage of the strain degrading raw Inner Mongolia lignite is only 23.16%. The degradation products were characterized. Proximate and ultimate analyses show that the higher oxygen content increased by photo-oxidation pretreatment maybe promoted the degradation process. Ultraviolet spectroscopy (UV) analysis of the liquid product reveals that it contains unsaturated structures and aromatic rings are the main structure units. Gas chromatography-mass spectrometry (GC-MS) analysis indicates that the main components of the ethyl acetate extracts are low molecular weight organic compounds, such as ketones, acids, hydrocarbons, esters and alcohols. Infrared spectroscopy (IR) analysis of raw lignite, photo-oxidized lignite and residual lignite demonstrates that the absorption peaks of functional groups in residual lignite disappeared or weakened obviously. Scanning electron microscopy (SEM) analysis manifests that small holes appear in photo-oxidized lignite surface, which may be promote the degradation process and this is only from the physical morphology aspects, so it can be inferred from the tests and analyses results that the more important reason of the high degradation percentage is mostly that the photo-oxidation pretreatment changes the chemical structures of lignite.

  10. Use of bovine catalase and manganese dioxide for elimination of hydrogen peroxide from partly oxidized aqueous solutions of aromatic molecules - Unexpected complications

    Science.gov (United States)

    Kovács, Krisztina; Sági, Gyuri; Takács, Erzsébet; Wojnárovits, László

    2017-10-01

    Being a toxic substance, hydrogen peroxide (H2O2) formed during application of advanced oxidation processes disturbs the biological assessment of the treated solutions. Therefore, its removal is necessary when the concentration exceeds the critical level relevant to the biological tests. In this study, H2O2 removal was tested using catalase enzyme or MnO2 as catalysts and the concentration changes were measured by the Cu(II)/phenanthroline method. MnO2 and Cu(II) were found to react not only with H2O2 but also with the partly oxidized intermediates formed in the hydroxyl radical induced degradation of aromatic antibiotic and pesticide compounds. Catalase proved to be a milder oxidant, it did not show significant effects on the composition of organic molecules. The Cu(II)/phenanthroline method gives the correct H2O2 concentration only in the absence of easily oxidizable compounds, e.g. certain phenol type molecules.

  11. Electro-oxidation of the dye azure B: kinetics, mechanism, and by-products.

    Science.gov (United States)

    Olvera-Vargas, Hugo; Oturan, Nihal; Aravindakumar, C T; Paul, M M Sunil; Sharma, Virender K; Oturan, Mehmet A

    2014-01-01

    In this work, the electrochemical degradation of the dye azure B in aqueous solutions was studied by electrochemical advanced oxidation processes (EAOPs), electro-Fenton, and anodic oxidation processes, using Pt/carbon-felt and boron-doped diamond (BDD)/carbon-felt cells with H₂O₂ electrogeneration. The higher oxidation power of the electro-Fenton (EF) process using BDD anode was demonstrated. The oxidative degradation of azure B by the electrochemically generated hydroxyl radicals ((•)OH) follows a pseudo-first-order kinetics. The apparent rate constants of the oxidation of azure B by (•)OH were measured according to pseudo-first-order kinetic model. The absolute rate constant of azure B hydroxylation reaction was determined by competition kinetics method and found to be 1.19 × 10(9) M(-1) s(-1). It was found that the electrochemical degradation of the dye leads to the formation of aromatic by-products which are then oxidized to aliphatic carboxylic acids before their almost mineralization to CO₂ and inorganic ions (sulfate, nitrate, and ammonium). The evolution of the TOC removal and time course of short-chain carboxylic acids during treatment were also investigated.

  12. Determination of oxidation products in radiolysis of halophenols with pulse radiolysis, hplc, and ion chromatography

    International Nuclear Information System (INIS)

    Ye, M.; Schuler, R.H.

    1990-01-01

    This paper reports on hydroxyl radicals that react with halogen substituted phenols by several different ways. One is addition of OH radicals to the aromatic ring, which is followed by elimination of hydrogen halide, H 2 O or H - . The positions of OH radicals attack are dependent on the nature of the halogen which affects the electronic distribution in the ring. The oxidation of fluorophenols, chlorophenols and bromophenols with hydroxyl radicals in N 2 O saturated solution has been investigated with pulse radiolysis and γ-irradiation experiments. The intermediates of the reactions were studied by pulse radiolysis. The products created in the γ-irradiation of aqueous solutions of halophenols were analyzed by ion chromatography and high performance liquid chromatography (HPLC). With the combination of time-resolved and steady-state experiments a complete and detailed description of radiolytic oxidation of halophenols by hydroxyl radicals was obtained

  13. Methods for forming complex oxidation reaction products including superconducting articles

    International Nuclear Information System (INIS)

    Rapp, R.A.; Urquhart, A.W.; Nagelberg, A.S.; Newkirk, M.S.

    1992-01-01

    This patent describes a method for producing a superconducting complex oxidation reaction product of two or more metals in an oxidized state. It comprises positioning at least one parent metal source comprising one of the metals adjacent to a permeable mass comprising at least one metal-containing compound capable of reaction to form the complex oxidation reaction product in step below, the metal component of the at least one metal-containing compound comprising at least a second of the two or more metals, and orienting the parent metal source and the permeable mass relative to each other so that formation of the complex oxidation reaction product will occur in a direction towards and into the permeable mass; and heating the parent metal source in the presence of an oxidant to a temperature region above its melting point to form a body of molten parent metal to permit infiltration and reaction of the molten parent metal into the permeable mass and with the oxidant and the at least one metal-containing compound to form the complex oxidation reaction product, and progressively drawing the molten parent metal source through the complex oxidation reaction product towards the oxidant and towards and into the adjacent permeable mass so that fresh complex oxidation reaction product continues to form within the permeable mass; and recovering the resulting complex oxidation reaction product

  14. Concerted effects in the reaction of ·OH radicals with aromatics: radiolytic oxidation of salicylic acid

    International Nuclear Information System (INIS)

    Albarran, G.; Schuler, R.H.

    2003-01-01

    Liquid chromatographic and capillary electrophoretic studies have been used to resolve the products produced in the radiolytic oxidation of salicylic acid in aqueous solution. These studies have shown that, as in the case of phenol, · OH radicals preferentially add to the positions ortho and para to the OH substituent. However, in contrast to its reaction with phenol, addition at the ortho position is favored over addition at the para position. Because · OH radical is a strong electrophile this difference suggests that the electron population at the ortho position in the salicylate anion is enhanced as a result of the hydrogen bonding in salicylic acid

  15. Catalytic aromatization of methane.

    Science.gov (United States)

    Spivey, James J; Hutchings, Graham

    2014-02-07

    Recent developments in natural gas production technology have led to lower prices for methane and renewed interest in converting methane to higher value products. Processes such as those based on syngas from methane reforming are being investigated. Another option is methane aromatization, which produces benzene and hydrogen: 6CH4(g) → C6H6(g) + 9H2(g) ΔG°(r) = +433 kJ mol(-1) ΔH°(r) = +531 kJ mol(-1). Thermodynamic calculations for this reaction show that benzene formation is insignificant below ∼600 °C, and that the formation of solid carbon [C(s)] is thermodynamically favored at temperatures above ∼300 °C. Benzene formation is insignificant at all temperatures up to 1000 °C when C(s) is included in the calculation of equilibrium composition. Interestingly, the thermodynamic limitation on benzene formation can be minimized by the addition of alkanes/alkenes to the methane feed. By far the most widely studied catalysts for this reaction are Mo/HZSM-5 and Mo/MCM-22. Benzene selectivities are generally between 60 and 80% at methane conversions of ∼10%, corresponding to net benzene yields of less than 10%. Major byproducts include lower molecular weight hydrocarbons and higher molecular weight substituted aromatics. However, carbon formation is inevitable, but the experimental findings show this can be kinetically limited by the use of H2 or oxidants in the feed, including CO2 or steam. A number of reactor configurations involving regeneration of the carbon-containing catalyst have been developed with the goal of minimizing the cost of regeneration of the catalyst once deactivated by carbon deposition. In this tutorial review we discuss the thermodynamics of this process, the catalysts used and the potential reactor configurations that can be applied.

  16. Polytetrafluoroethylene-jacketed stirrer modified with graphene oxide and polydopamine for the efficient extraction of polycyclic aromatic hydrocarbons.

    Science.gov (United States)

    Zhang, Zinxin; Mwadini, Mwadini Ahmada; Chen, Zilin

    2016-10-01

    Steel stirrers jacketed with polytetrafluoroethylene can be regarded as an ideal substrate for stirrer bar sorptive extraction. However, it is still a great challenge to immobilize graphene onto a polytetrafluoroethylene stirrer due to the high chemical resistance of the surface of a polytetrafluoroethylene stirrer. We describe here a method to modify the surface of polytetrafluoroethylene stirrers with graphene. In this work, graphene was used as the sorbent due to its excellent adsorption capability for aromatic compounds, such as polycyclic aromatic compounds. Graphene was successfully immobilized onto polytetrafluoroethylene-stirrer by a bio-inspired polydopamine functionalization method. The graphene-modified polytetrafluoroethylene-stirrer shows good stability and tolerance to stirring, ultrasonication, strong acidic and basic solutions, and to organic solvents. The multilayer coating was characterized by scanning electronic microscopy and Fourier transform infrared spectroscopy. After the optimization of some experimental conditions, the graphene-modified polytetrafluoroethylene stirrer was used for the stirrer bar sorptive extraction of polycyclic aromatic hydrocarbons, in which the binding between the polycyclic aromatic hydrocarbons and the graphene layer was mainly based on π-π stacking and hydrophobic interactions. The graphene-modified polytetrafluoroethylene-stirrer-based stirrer bar sorptive extraction and high-performance liquid chromatography method was developed for the determination of polycyclic aromatic hydrocarbons with great extraction efficiency, with enrichment factors from 18 to 62. The method has low limits of detection of 1-5 pg/mL, wide linear range (5-100 and 10-200 pg/mL), good linearity (R ≥ 0.9957) and good reproducibility (RSD ≤ 6.45%). The proposed method has been applied to determine polycyclic aromatic hydrocarbons in real dust samples. Good recoveries were obtained, ranging from 88.53 to 109.43%. © 2016 WILEY-VCH Verlag

  17. Solid oxide fuel cells and hydrogen production

    International Nuclear Information System (INIS)

    Dogan, F.

    2009-01-01

    'Full text': A single-chamber solid oxide fuel cell (SC-SOFC), operating in a mixture of fuel and oxidant gases, provides several advantages over the conventional SOFC such as simplified cell structure (no sealing required). SC-SOFC allows using a variety of fuels without carbon deposition by selecting appropriate electrode materials and cell operating conditions. The operating conditions of single chamber SOFC was studied using hydrocarbon-air gas mixtures for a cell composed of NiO-YSZ / YSZ / LSCF-Ag. The cell performance and catalytic activity of the anode was measured at various gas flow rates. The results showed that the open-circuit voltage and the power density increased as the gas flow rate increased. Relatively high power densities up to 660 mW/cm 2 were obtained in a SC-SOFC using porous YSZ electrolytes instead of dense electrolytes required for operation of a double chamber SOFC. In addition to propane- or methane-air mixtures as a fuel source, the cells were also tested in a double chamber configuration using hydrogen-air mixtures by controlling the hydrogen/air ratio at the cathode and the anode. Simulation of single chamber conditions in double chamber configurations allows distinguishing and better understanding of the electrode reactions in the presence of mixed gases. Recent research efforts; the effect of hydrogen-air mixtures as a fuel source on the performance of anode and cathode materials in single-chamber and double-chamber SOFC configurations,will be presented. The presentation will address a review on hydrogen production by utilizing of reversible SOFC systems. (author)

  18. Oxidative cleavage of non-phenolic β-O-4 lignin model dimers by an extracellular aromatic peroxygenase

    Science.gov (United States)

    Matthias Kinne; Marzena Poraj-Kobielska; Rene Ullrich; Paula Nousiainen; Jussi Sipilä; Katrin Scheibner; Kenneth E. Hammel; Martin Hofrichter

    2011-01-01

    The extracellular aromatic peroxygenase of the agaric fungus Agrocybe aegerita catalyzed the H2O2-dependent cleavage of non-phenolic arylgiycerol-ß-aryl ethers (ß-O-4 ethers). For instance 1-(3,4-dimethoxyphenyl)-2-(2-methoxy-phenoxy)propane-1,3-diol, a recalcitrant dimeric lignin model compound that represents the major...

  19. Measuring protection of aromatic wine thiols from oxidation by competitive reactions vs wine preservatives with ortho-quinones.

    Science.gov (United States)

    Nikolantonaki, Maria; Magiatis, Prokopios; Waterhouse, Andrew L

    2014-11-15

    Quinones are central intermediates in wine oxidation that can degrade the quality of wine by reactions with varietal thiols, such as 3-sulfanylhexanol, decreasing desirable aroma. Protection by wine preservatives (sulphur dioxide, glutathione, ascorbic acid and model tannin, phloroglucinol) was assessed by competitive sacrificial reactions with 4-methyl-1,2-benzoquinone, quantifying products and ratios by HPLC-UV-MS. Regioselectivity was assessed by product isolation and identification by NMR spectroscopy. Nucleophilic addition reactions compete with two electron reduction of quinones by sulphur dioxide or ascorbic acid, and both routes serve as effective quenching pathways, but minor secondary products from coupled redox reactions between the products and reactants are also observed. The wine preservatives were all highly reactive and thus all very protective against 3-sulfanylhexanol loss to the quinone, but showed only additive antioxidant effects. Confirmation of these reaction rates and pathways in wine is needed to assess the actual protective action of each tested preservative. Copyright © 2014 Elsevier Ltd. All rights reserved.

  20. Graphene oxide bonded fused-silica fiber for solid-phase microextraction-gas chromatography of polycyclic aromatic hydrocarbons in water.

    Science.gov (United States)

    Xu, Lili; Feng, Juanjuan; Li, Jubai; Liu, Xia; Jiang, Shengxiang

    2012-01-01

    A novel chemically bonded graphene oxide/fused-silica fiber was prepared and applied in solid-phase microextraction of six polycyclic aromatic hydrocarbons from water samples coupled with gas chromatography. It exhibited high extraction efficiency and excellent stability. Effects of extraction time, extraction temperature, ionic strength, stirring rate and desorption conditions were investigated and optimized in our work. Detection limits to the six polycyclic aromatic hydrocarbons were less than 0.08 μg/L, and their calibration curves were all linear (R(2)≥0.9954) in the range from 0.05 to 200 μg/L. Single fiber repeatability and fiber-to-fiber reproducibility were less than 6.13 and 15.87%, respectively. This novel fiber was then utilized to analyze two real water samples from the Yellow River and local waterworks, and the recoveries of samples spiked at 1 and 10 μg/L ranged from 84.48 to 118.24%. Compared with other coating materials, this graphene oxide-coated fiber showed many advantages: wide linear range, low detection limit, and good stability in acid, alkali, organic solutions and at high temperature. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  1. Oxidation kinetics of reaction products formed in uranium metal corrosion

    International Nuclear Information System (INIS)

    Totemeier, T. C.

    1998-01-01

    The oxidation behavior of uranium metal ZPPR fuel corrosion products in environments of Ar-4%O 2 and Ar-20%O 2 were studied using thermo-gravimetric analysis (TGA). These tests were performed to extend earlier work in this area specifically, to assess plate-to-plate variations in corrosion product properties and the effect of oxygen concentration on oxidation behavior. The corrosion products from two relatively severely corroded plates were similar, while the products from a relatively intact plate were not reactive. Oxygen concentration strongly affected the burning rate of reactive products, but had little effect on low-temperature oxidation rates

  2. Oxidation kinetics of reaction products formed in uranium metal corrosion.

    Energy Technology Data Exchange (ETDEWEB)

    Totemeier, T. C.

    1998-04-22

    The oxidation behavior of uranium metal ZPPR fuel corrosion products in environments of Ar-4%O{sub 2} and Ar-20%O{sub 2} were studied using thermo-gravimetric analysis (TGA). These tests were performed to extend earlier work in this area specifically, to assess plate-to-plate variations in corrosion product properties and the effect of oxygen concentration on oxidation behavior. The corrosion products from two relatively severely corroded plates were similar, while the products from a relatively intact plate were not reactive. Oxygen concentration strongly affected the burning rate of reactive products, but had little effect on low-temperature oxidation rates.

  3. Adsorption of Polycyclic aromatic hydrocarbons (fluoranthene and anthracenemethanol) by functional graphene oxide and removal by pH and temperature-sensitive coagulation.

    Science.gov (United States)

    Zhang, Caili; Wu, Lin; Cai, Dongqing; Zhang, Caiyun; Wang, Ning; Zhang, Jing; Wu, Zhengyan

    2013-06-12

    A new kind of functional graphene oxide with fine stability in water was fabricated by mixing graphene oxide (GO) and brilliant blue (BB) with a certain weight ratio. The adsorption performance of this mixture of BB and GO (BBGO) to polycyclic aromatic hydrocarbons (anthracenemethanol (AC) and fluoranthene (FL)) was investigated, and the results indicated BBGO possessed adsorption capacity of 1.676 mmol/g and removal efficiency of 72.7% as to AC and adsorption capacity of 2.212 mmol/g and removal efficiency of 93.2% as to FL. After adsorption, pH and temperature-sensitive coagulation (PTC) method was used to remove the AC/BBGO or FL/BBGO complex and proved to be an effective approach to flocculate the AC/BBGO or FL/BBGO complex into large flocs, which tended to be removed from the aqueous solution.

  4. Parametric study of two-stage hydropyrolysis of lignocellulosic biomass for production of gaseous and light aromatic hydrocarbons.

    Science.gov (United States)

    Zheng, Nan; Zhang, Jie; Wang, Jie

    2017-11-01

    Non-catalytic hydropyrolysis of pinewood and its components was carried out using a two-stage reactor. The main aim of this work is to investigate the hydrodeoxygenation and hydrogenation of volatile matter in the post hydrocracking reactor for oriented production of gaseous and light aromatic hydrocarbons. A portion of volatile matter, which evolved from hemicellulose, neutral extractives and lignin below 275°C, was found to be thoroughly hydrodeoxygenated preventing the release of CO 2 and CO. Increasing hydrocracking temperature from 600°C to 750°C and pressure from 1.0MPa to 5.0MPa strongly facilitated the hydrogenation reactions to target products. The summed yield of CH 4 and C 2 H 6 (dry biomass basis) reached up to 33.2% at a hydrocracking temperature of 750°C and 5.0MPa, with a concomitant 5.1% yield of BTX. All components in pinewood significantly contributed to the production of CH 4 and BTX by hydropyrolysis, differing from the case of pyrolysis. Copyright © 2017 Elsevier Ltd. All rights reserved.

  5. Synthesis of zirconia-immobilized copper chelates for catalytic decomposition of hydrogen peroxide and the oxidation of polycyclic aromatic hydrocarbons

    Czech Academy of Sciences Publication Activity Database

    Baldrian, Petr; Merhautová, Věra; Cajthaml, Tomáš; Nerud, František; Stopka, Pavel; Gorbacheva, O.; Hrubý, Martin; Beneš, Milan J.

    2008-01-01

    Roč. 72, č. 11 (2008), s. 1721-1726 ISSN 0045-6535 R&D Projects: GA AV ČR IBS5020306 Institutional research plan: CEZ:AV0Z50200510; CEZ:AV0Z40320502; CEZ:AV0Z40500505 Keywords : degradation * polycyclic aromatic hydrocarbons * hydrogen peroxide Subject RIV: EE - Microbiology, Virology Impact factor: 3.054, year: 2008

  6. Processes controlling the production of aromatic water-soluble organic matter during litter decomposition

    NARCIS (Netherlands)

    Klotzbücher, T.; Kaiser, K.; Filley, T.R.; Kalbitz, K.

    2013-01-01

    Dissolved organic matter (DOM) plays a fundamental role for many soil processes. For instance, production, transport, and retention of DOM control properties and long-term storage of organic matter in mineral soils. Production of water-soluble compounds during the decomposition of plant litter is a

  7. Polycyclic Aromatic Hydrocarbons (PAH) in Danish Smoked Fish and Meat Products

    DEFF Research Database (Denmark)

    Duedahl-Olesen, Lene; White, S.; Binderup, Mona-Lise

    2006-01-01

    Twenty seven PAH were detected in 45 selected smoked food samples produced in Denmark, including mackerel, herring, trout, small sausages, salami, and bacon. The sum of PAH in smoked meat products ranged from 24 mu g/kg for salami to 64 mu g/kg in bacon, while those in fish products ranged from 2...

  8. A fungal P450 (CYP5136A3 capable of oxidizing polycyclic aromatic hydrocarbons and endocrine disrupting alkylphenols: role of Trp(129 and Leu(324.

    Directory of Open Access Journals (Sweden)

    Khajamohiddin Syed

    Full Text Available The model white rot fungus Phanerochaete chrysosporium, which is known for its versatile pollutant-biodegradation ability, possesses an extraordinarily large repertoire of P450 monooxygenases in its genome. However, the majority of these P450s have hitherto unknown function. Our initial studies using a genome-wide gene induction strategy revealed multiple P450s responsive to individual classes of xenobiotics. Here we report functional characterization of a cytochrome P450 monooxygenase, CYP5136A3 that showed common responsiveness and catalytic versatility towards endocrine-disrupting alkylphenols (APs and mutagenic/carcinogenic polycyclic aromatic hydrocarbons (PAHs. Using recombinant CYP5136A3, we demonstrated its oxidation activity towards APs with varying alkyl side-chain length (C3-C9, in addition to PAHs (3-4 ring size. AP oxidation involves hydroxylation at the terminal carbon of the alkyl side-chain (ω-oxidation. Structure-activity analysis based on a 3D model indicated a potential role of Trp(129 and Leu(324 in the oxidation mechanism of CYP5136A3. Replacing Trp(129 with Leu (W129L and Phe (W129F significantly diminished oxidation of both PAHs and APs. The W129L mutation caused greater reduction in phenanthrene oxidation (80% as compared to W129F which caused greater reduction in pyrene oxidation (88%. Almost complete loss of oxidation of C3-C8 APs (83-90% was observed for the W129L mutation as compared to W129F (28-41%. However, the two mutations showed a comparable loss (60-67% in C9-AP oxidation. Replacement of Leu(324 with Gly (L324G caused 42% and 54% decrease in oxidation activity towards phenanthrene and pyrene, respectively. This mutation also caused loss of activity towards C3-C8 APs (20-58%, and complete loss of activity toward nonylphenol (C9-AP. Collectively, the results suggest that Trp(129 and Leu(324 are critical in substrate recognition and/or regio-selective oxidation of PAHs and APs. To our knowledge, this is the first

  9. New oxidation and photo-oxidation products of tryptophan

    International Nuclear Information System (INIS)

    Savige, W.E.

    1975-01-01

    Dye-sensitized photo-oxidation of tryptophan in water gives N'-formylkynurenine and (+-)-3a-hydroxy-1,2,3a,8,8a-hexahydropyrrolo[2,3-b] indole-2-carboxylic acid. The latter rearranges to oxindolyl-3-alanine on irradiation with UV light and reacts with thiols, including cysteine, in warm 20% acetic acid to give the corresponding 2-tryptophyl sulphides. (orig.) [de

  10. Nano cobalt oxides for photocatalytic hydrogen production

    KAUST Repository

    Mangrulkar, Priti A.; Joshi, Meenal M.; Tijare, Saumitra N.; Polshettiwar, Vivek; Labhsetwar, Nitin K.; Rayalu, Sadhana Suresh

    2012-01-01

    of various operating parameters in hydrogen generation by nano cobalt oxide was then studied in detail. Copyright © 2012, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved.

  11. Nano cobalt oxides for photocatalytic hydrogen production

    KAUST Repository

    Mangrulkar, Priti A.

    2012-07-01

    Nano structured metal oxides including TiO 2, Co 3O 4 and Fe 3O 4 have been synthesized and evaluated for their photocatalytic activity for hydrogen generation. The photocatalytic activity of nano cobalt oxide was then compared with two other nano structured metal oxides namely TiO 2 and Fe 3O 4. The synthesized nano cobalt oxide was characterized thoroughly with respect to EDX and TEM. The yield of hydrogen was observed to be 900, 2000 and 8275 mmol h -1 g -1 of photocatalyst for TiO 2, Co 3O 4 and Fe 3O 4 respectively under visible light. It was observed that the hydrogen yield in case of nano cobalt oxide was more than twice to that of TiO 2 and the hydrogen yield of nano Fe 3O 4 was nearly four times as compared to nano Co 3O 4. The influence of various operating parameters in hydrogen generation by nano cobalt oxide was then studied in detail. Copyright © 2012, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved.

  12. Reinforced microextraction of polycyclic aromatic hydrocarbons from polluted soil samples using an in-needle coated fiber with polypyrrole/graphene oxide nanocomposite.

    Science.gov (United States)

    Behfar, Mina; Ghiasvand, Ali Reza; Yazdankhah, Fatemeh

    2017-07-01

    The surface of a stainless-steel wire was platinized using electrophoretic deposition method to create a high-surface-area with porous and cohesive substrate. The platinized fiber was coated by the polypyrrole/graphene oxide nanocomposite by electropolymerization and accommodated into a stainless-steel needle to fabricate an in-needle coated fiber. The developed setup was coupled to gas chromatography with flame ionization detection and applied to extract and determine polycyclic aromatic hydrocarbons (naphthalene, fluorene, phenanthrene, fluoranthene, and pyrene) in complicated solid matrices, along with reinforcement of the extraction by cooling the sorbent, using liquid carbon dioxide. To obtain the best extraction efficiency, the important experimental variables including extraction temperature and time, temperature of cooled sorbent, sampling flow rate, and desorption condition were studied. Under the optimal condition, limits of detection for five studied analytes were in the range of 0.2-0.8 pg/g. Linear dynamic ranges for the calibration curves were found to be in the range of 0.001-1000 ng/g. Relative standard deviations obtained for six replicated analyses of 1 ng/g of analytes were 4.9-13.5%. The reinforced in-needle coated fiber method was successfully applied for the analysis of polycyclic aromatic hydrocarbons in contaminated soil samples. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  13. Aromatic chemical feedstocks from coal

    Energy Technology Data Exchange (ETDEWEB)

    Collin, G

    1982-06-01

    Liquid byproducts of coal carbonization meet some 25% of the world demand for aromatic chemicals, currently at approx. 30 million t/a, in particular 15% of the demand for benzene and over 95% of the demand for condensed aromatics and heteroaromatics. Industrial processing of the aromatic byproducts of coal pressure gasification is carried out to only a minor extent. Other methods that may be employed in future to obtain carbochemical aromatic compounds are solvolysis and supercritical gas extraction, the catalytic liquid-phase hydrogenation and hydropyrolysis of coal, which also permit recovery of benzene and homologues, phenols, and condensed and partially hydrogenated aromatics, and the synthesis of aromatics using methanol as the key compound. As with the present means of obtaining aromatic chemicals from coal, the processes that may in the future be applied on an industrial scale to obtain pure aromatics will only be economically feasible if linked with the manufacture of other mass products and combined with the present production of carbochemical aromatics.

  14. Aromatic raw materials from coal

    Energy Technology Data Exchange (ETDEWEB)

    Collin, G

    1982-06-01

    Liquid byproducts of coal carbonization meet some 25% of the world demand for aromatic chemicals, currently at approx. 30 million t/a, in particular 15% of the demand for benzene and over 95% of the demand for condensed aromatics and heteroaromatics. Industrial processing of the aromatic byproducts of coal pressure gasification is carried out to only a minor extent. Other methods that may be employed in future to obtain carbochemical aromatic compounds are solvolysis and supercritical gas extraction, the catalytic liquid-phase hydrogenation and hydropyrolysis of coal, which also permit recovery of benzene and homologues, phenols, and condensed and partially hydrogenated aromatics, and the synthesis of aromatics using methanol as the key compound. As with the present means of obtaining aromatic chemicals from coal, the processes that may in future be applied on an industrial scale to obtain pure aromatics will only be economically feasible if linked with the manufacture of other mass products and combined with the present production of carbochemical aromatics. (In German)

  15. H18F: production and use in aromatic fluorinations via triazenes

    International Nuclear Information System (INIS)

    Kilbourn, M.R.; Saji, H.; Welch, M.J.

    1982-01-01

    Studies with the triazene method of radiofluorination are presented, including the production and use of anhydrous H 18 F, investigations into the best reaction conditions, and studies of the stability and purification of the 18 F-labeled products. Despite problems with low yields, the use of triazenes in the prepartion of fluorine-18 labeled receptor ligands remains a sound synthetic approach, and the only one available for no-carrier-added syntheses. However, it appears that the fluorine-18 fluorination yields are much higher with simpler triazenes. For this reason, synthetic efforts are now focused on the preparation of 18 F-spiroperidol by a convergent synthesis

  16. IN VITRO CYTOTOXICITY OF AROMATIC AEROBIC BIOTRANSFORMATION PRODUCTS IN BLUEGILL SUNFISH BF-2 CELLS

    Science.gov (United States)

    Toluene (methylbenzene) is a common environmental pollutant that is found in many hazardous waste sites and it is an aquifer contaminant. A concern is the potential risk to human and ecosystem health due to exposure to toluene and its major biotransformation products. The cytotox...

  17. Bacterial degradation of monocyclic aromatic amines

    Directory of Open Access Journals (Sweden)

    Pankaj Kumar Arora

    2015-08-01

    Full Text Available Aromatic amines are an important group of industrial chemicals, which are widely used for manufacturing of dyes, pesticides, drugs, pigments, and other industrial products. These compounds have been considered highly toxic to human beings due to their carcinogenic nature. Three groups of aromatic amines have been recognized: monocyclic, polycyclic and heterocyclic aromatic amines. Bacterial degradation of several monocyclic aromatic compounds has been studied in a variety of bacteria, which utilizes monocyclic aromatic amines as their sole source of carbon and energy. Several degradation pathways have been proposed and the related enzymes and genes have also been characterized. Many reviews have been reviewed toxicity of monocyclic aromatic amines; however, there is lack of review on biodegradation of monocyclic aromatic amines. The aim of this review is to summarize bacterial degradation of monocyclic aromatic amines. This review will increase our current understanding of biochemical and molecular basis of bacterial degradation of monocyclic aromatic amines.

  18. Enhancing and inhibiting effects of aromatic compounds on luminol-dimethylsulfoxide-OH(-) chemiluminescence and determination of intermediates in oxidative hair dyes by HPLC with chemiluminescence detection.

    Science.gov (United States)

    Zhou, Jian; Xu, Hong; Wan, Guo-Hui; Duan, Chun-Feng; Cui, Hua

    2004-10-08

    The effect of 36 aromatic compounds on the luminol-dimethylsulfoxide-OH(-) chemiluminescence (CL) was systematically studied. It was found that dihydroxybenzenes, and ortho- and para-substituted aminophenols and phenylenediamines inhibited the CL and phenols with three or more than three hydroxyls except phloroglucin tended to enhance the CL. The CL inhibition and enhancement was proposed to be dependent on whether superoxide anion radical (O(2)(-)) was competitively consumed by compounds in the CL system. Trihydroxybenzenes were capable of generating superoxide anion radical, leading to the CL enhancement, whereas dihydroxybenzenes were superoxide anion radical scavenger, causing the CL inhibition. Based on the inhibited CL, a novel method for the simultaneous determination of p-phenylenediamine, o-phenylenediamine, p-aminophenol, o-aminophenol, resorcinol and hydroquinone by high-performance liquid chromatography coupled with chemiluminescence detection was developed. The method has been successfully applied to determine intermediates in oxidative hair dyes and wastewater of shampooing after hair dyed.

  19. Effects of polycyclic aromatic hydrocarbons (PAHs) in environmental pollution on exogenous and oxidative DNA damage (EXPAH project): description of the population under study.

    Science.gov (United States)

    Taioli, Emanuela; Sram, Radim J; Garte, Seymour; Kalina, Ivan; Popov, Todor A; Farmer, Peter B

    2007-07-01

    The EXPAH project was a molecular epidemiology study whose aims were to evaluate the hypothesis that polycyclic aromatic hydrocarbons (PAHs) are a major source of genotoxic activities of organic mixtures associated with air pollution. Biomarkers of exposure, effects and susceptibility, and oxidative DNA damage were measured in three PAH-exposed populations from Prague (Czech Republic), Kosice (Slovakia) and Sofia (Bulgaria). Control populations were included from each city. In total 356 individuals were enrolled. A questionnaire was used to determine life style/dietary factors. Ambient air exposure was measured by stationary monitoring, and personal exposure monitoring was also carried out. The characteristics of the population are described in this paper together with their personal exposure to carcinogenic PAHs (c-PAHs). The dose of c-PAH exposure was found to vary between the occupationally exposed (e.g. policemen and bus drivers) and the control populations in each country, and also varied from country to country.

  20. The Evonik-Uhde HPPO process for proplene oxide production

    Energy Technology Data Exchange (ETDEWEB)

    Jaeger, B.; Baerz, M. [Evonik Industries, Hanau (Germany); Schemel, J.; Kolbe, B. [Uhde GmbH, Dortmund/Bad Soden (Germany)

    2011-07-01

    In 2008 the HPPO technology has shown up as an economically and environmentally friendly alternative for manufacturing of propylene oxide. The HPPO technology offers the advantage of an on purpose process for manufacturing of propylene oxide without dependency on disposal or marketing of coupling products. (orig.)

  1. Catalytic abatement of nitrous oxide from nitric and production

    NARCIS (Netherlands)

    Oonk, J.

    1998-01-01

    Nitric acid production is identified as a main source of nitrous oxide. Options for emission reduction however are not available. TNO and Hydro Agri studied the technological and economic feasibility of catalytic decomposition of nitrous oxide in nitric acid tail-gases. Although in literature

  2. Production of beryllium oxide of nuclear purity from beryl

    Energy Technology Data Exchange (ETDEWEB)

    Copat, A; Sood, S P

    1984-01-01

    Production of beryllium oxide from beryl by the fluoride process was optimized in this study. Optimum results were obtained using a mixture of sodium hexafluorsilicate and sodium hexafluorferrate as flux and calcinating at 740/sup 0/C for 2 hours. The beryllium concentrate produced was further purified by crystallization as beryllium sulfate to obtain nuclear grade beryllium oxide

  3. Production of beryllium oxide of nuclear purity from beryl

    International Nuclear Information System (INIS)

    Copat, A.; Sood, S.P.

    1983-01-01

    Production of beryllium oxide from beryl by the fluoride process was optimized in this study. Optimum results were obtained using a mixture of sodium hexafluorsilicate and sodium hexafluorferrate as flux and calcinating at 740 0 C for 2 hours. The beryllium concentrate produced was further purified by crystallization as beryllium sulfate to obtain nuclear grade beryllium oxide (Author) [pt

  4. Review of the quantification techniques for polycyclic aromatic hydrocarbons (PAHs) in food products.

    Science.gov (United States)

    Bansal, Vasudha; Kumar, Pawan; Kwon, Eilhann E; Kim, Ki-Hyun

    2017-10-13

    There is a growing need for accurate detection of trace-level PAHs in food products due to the numerous detrimental effects caused by their contamination (e.g., toxicity, carcinogenicity, and teratogenicity). This review aims to discuss the up-to-date knowledge on the measurement techniques available for PAHs contained in food or its related products. This article aims to provide a comprehensive outline on the measurement techniques of PAHs in food to help reduce their deleterious impacts on human health based on the accurate quantification. The main part of this review is dedicated to the opportunities and practical options for the treatment of various food samples and for accurate quantification of PAHs contained in those samples. Basic information regarding all available analytical measurement techniques for PAHs in food samples is also evaluated with respect to their performance in terms of quality assurance.

  5. A comparative study on aromatic profiles of strawberry vinegars obtained using different conditions in the production process.

    Science.gov (United States)

    Ubeda, Cristina; Callejón, Raquel M; Troncoso, Ana M; Moreno-Rojas, Jose M; Peña, Francisco; Morales, M Lourdes

    2016-02-01

    Impact odorants in strawberry vinegars produced in different containers (glass, oak and cherry barrels) were determined by gas chromatography-olfactometry using modified frequency (MF) technique, and dynamic headspace gas chromatography-mass spectrometry. Aromatic profile of vinegar from strawberry cooked must was also studied. All strawberry vinegars retained certain impact odorants from strawberries: 3-nonen-2-one, (E,E)-2,4-decadienal, guaiacol, nerolidol, pantolactone+furaneol, eugenol, γ-dodecalactone and phenylacetic acid. Isovaleric acid, pantolactone+furaneol, p-vinylguaiacol, phenylacetic acid and vanillin were the most important aroma-active compounds in all vinegars. The strawberry cooked must vinegar accounted for the highest number of impact odorants. Wood barrels provided more aroma complexity than glass containers. Impact odorants with grassy characteristics were predominant in vinegar from glass containers, and those with sweet and fruity characteristics in vinegars from wood barrels. Principal component analysis indicated that the production process led to differences in the impact odorants. Copyright © 2015 Elsevier Ltd. All rights reserved.

  6. Dispersion modeling of polycyclic aromatic hydrocarbons from combustion of biomass and fossil fuels and production of coke in Tianjin, China.

    Science.gov (United States)

    Tao, Shu; Li, Xinrong; Yang, Yu; Coveney, Raymond M; Lu, Xiaoxia; Chen, Haitao; Shen, Weiran

    2006-08-01

    A USEPA, procedure, ISCLT3 (Industrial Source Complex Long-Term), was applied to model the spatial distribution of polycyclic aromatic hydrocarbons (PAHs) emitted from various sources including coal, petroleum, natural gas, and biomass into the atmosphere of Tianjin, China. Benzo[a]pyrene equivalent concentrations (BaPeq) were calculated for risk assessment. Model results were provisionally validated for concentrations and profiles based on the observed data at two monitoring stations. The dominant emission sources in the area were domestic coal combustion, coke production, and biomass burning. Mainly because of the difference in the emission heights, the contributions of various sources to the average concentrations at receptors differ from proportions emitted. The shares of domestic coal increased from approximately 43% at the sources to 56% at the receptors, while the contributions of coking industry decreased from approximately 23% at the sources to 7% at the receptors. The spatial distributions of gaseous and particulate PAHs were similar, with higher concentrations occurring within urban districts because of domestic coal combustion. With relatively smaller contributions, the other minor sources had limited influences on the overall spatial distribution. The calculated average BaPeq value in air was 2.54 +/- 2.87 ng/m3 on an annual basis. Although only 2.3% of the area in Tianjin exceeded the national standard of 10 ng/m3, 41% of the entire population lives within this area.

  7. Rate of hexabromocyclododecane decomposition and production of brominated polycyclic aromatic hydrocarbons during combustion in a pilot-scale incinerator.

    Science.gov (United States)

    Miyake, Yuichi; Tokumura, Masahiro; Wang, Qi; Amagai, Takashi; Horii, Yuichi

    2017-11-01

    Here, we examined the incineration of extruded polystyrene containing hexabromocyclododecane (HBCD) in a pilot-scale incinerator under various combustion temperatures (800-950°C) and flue gas residence times (2-8sec). Rates of HBCD decomposition ranged from 99.996% (800°C, 2sec) to 99.9999% (950°C, 8sec); the decomposition of HBCD, except during the initial stage of combustion (flue gas residence timepolycyclic aromatic hydrocarbons (BrPAHs) were detected as unintentional by-products. Of the 11 BrPAHs detected, 2-bromoanthracene and 1-bromopyrene were detected at the highest concentrations. The mutagenic and carcinogenic BrPAHs 1,5-dibromoanthracene and 1-bromopyrene were most frequently detected in the flue gases analyzed. The total concentration of BrPAHs exponentially increased (range, 87.8-2,040,000ng/m 3 ) with increasing flue gas residence time. Results from a qualitative analysis using gas chromatography/high-resolution mass spectrometry suggest that bromofluorene and bromopyrene (or fluoranthene) congeners were also produced during the combustion. Copyright © 2017. Published by Elsevier B.V.

  8. Chemical oxidation of unsymmetrical dimethylhydrazine transformation products in water

    NARCIS (Netherlands)

    Abilev, M.; Kenessov, B.N.; Batyrbekova, S.; Grotenhuis, J.T.C.

    2015-01-01

    Oxidation of unsymmetrical dimethylhydrazine (UDMH) during a water treatment has several disadvantages including formation of stable toxic byproducts. Effectiveness of treatment methods in relation to UDMH transformation products is currently poorly studied. This work considers the effectiveness of

  9. Effect of substituted hydroxyl groups in the changes of solution turbidity in the oxidation of aromatic contaminants.

    Science.gov (United States)

    Villota, N; Jm, Lomas; Lm, Camarero

    2017-01-01

    This paper deals with the changes of turbidity that are generated in aqueous solutions of phenol when they are oxidized by using different Fenton technologies. Results revealed that if the Fenton reaction was promoted with UV light, the turbidity that was generated in the water doubled. Alternatively, the use of ultrasonic waves produced an increase in turbidity which initially proceeded slowly, reaching intensities eight times higher than in the conventional Fenton treatment. As well, the turbidity showed a high dependence on pH. It is therefore essential to control acidity throughout the reaction. The maximum turbidity was generated when operating at pH = 2.0, and it slowly decreased with increasing to a value of pH = 3.0, at which the turbidity was the lowest. This result was a consequence of the presence of ferric ions in solution. At pH values greater than 3.5, the turbidity increased almost linearly until at pH = 5.0 reached its maximum intensity. In this range, ferrous ions may generate an additional contribution of radicals that promote the degradation of the phenol species that produce turbidity. Turbidity was enhanced at ratios R = 4.0 mol H 2 O 2 /mol C 6 H 6 O. This value corresponds to the stoichiometric ratio that leads to the production of turbidity-precursor species. Therefore, muconic acid would be a species that generate high turbidity in solution according to its isomerism. Also, the results revealed that the turbidity is not a parameter to which species contribute additively since interactions may occur among species that would enhance their individual contributions to it. Analyzing the oxidation of phenol degradation intermediates, the results showed that meta-substituted compounds (resorcinol) generate high turbidity in the wastewater. The presence of polar molecules, such as muconic acid, would provide the structural features that are necessary for resorcinol to act as a clip between two carboxylic groups, thus establishing

  10. 40 CFR 415.50 - Applicability; description of the calcium oxide production subcategory.

    Science.gov (United States)

    2010-07-01

    ... calcium oxide production subcategory. 415.50 Section 415.50 Protection of Environment ENVIRONMENTAL... SOURCE CATEGORY Calcium Oxide Production Subcategory § 415.50 Applicability; description of the calcium... the production of calcium oxide. ...

  11. Method for production of transparent yttrium oxide

    International Nuclear Information System (INIS)

    Dutta, S.K.; Gazza, G.A.

    1975-01-01

    The method comprises vacuum hot pressing the yttrium oxide (Y 2 O 3 ) powder in a graphite die at temperatures of between 1300 to 1500 0 C and uniaxial pressures of between 5000 to 7000 psi, for a period of 1 to 2 hours. (U.S.)

  12. Cholesterol oxidation products and their biological importance

    Czech Academy of Sciences Publication Activity Database

    Kulig, W.; Cwiklik, Lukasz; Jurkiewicz, P.; Rog, T.; Vattulainen, I.

    2016-01-01

    Roč. 199, Sep (2016), s. 144-160 ISSN 0009-3084 R&D Projects: GA ČR(CZ) GBP208/12/G016 Institutional support: RVO:61388963 Keywords : cholesterol * oxidation * oxysterols * biological membranes * biophysical properties Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 3.361, year: 2016

  13. NADPH oxidases in Microglia oxidant production

    DEFF Research Database (Denmark)

    Haslund-Vinding, J; McBean, G; Jaquet, V

    2017-01-01

    inhibitors. Finally, we review the recent literature on NOX and other sources of ROS that are involved in activation of the inflammasome and discuss the potential influence of microglia-derived oxidants on neurogenesis, neural differentiation and culling of surplus progenitor cells. The degree to which...

  14. Cholesterol oxidation products and their biological importance

    Czech Academy of Sciences Publication Activity Database

    Kulig, W.; Cwiklik, Lukasz; Jurkiewicz, Piotr; Rog, T.; Vattulainen, I.

    2016-01-01

    Roč. 199, SI (2016), s. 144-160 ISSN 0009-3084 R&D Projects: GA ČR(CZ) GBP208/12/G016; GA ČR GA15-14292S Institutional support: RVO:61388955 Keywords : cholesterol * oxidation * oxysterols Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 3.361, year: 2016

  15. Lipid oxidation. Part 2. Oxidation products of olive oil methyl esters.

    Science.gov (United States)

    Pokorný, J; Tài, P; Parízková, H; Smidrkalová, E; El-Tarras, M F; Janícek, G

    1976-01-01

    Olive oil was converted into methyl esters which were autoxidized at 60 degrees C. The composition of oxidized products was determined by the comparison of infrared spectra and NMR spectra of the original and acetylated samples, the sample reduced with potassium iodide and the acetylated reduced sample. Oxidized products were separated by preparative thin layer chromatography on silica gel and characterized by selective detection and by infrared spectrometry of the fractions. The oxidation products consisted of hydroperoxido butyl oleate, substituted hydroperoxides, mono- and disubstituted monomeric derivatives and a small amount of oligomers.

  16. Degradation of aromatic compounds in plants grown under aseptic conditions

    Energy Technology Data Exchange (ETDEWEB)

    Mithaishvili, T.; Ugrekhelidze, D.; Tsereteli, B.; Sadunishvili, T.; Kvesitadze, G. [Durmishidze Inst. of Biochemistry and Biotechnology, Academy of Sciences of Georgia, Tbilisi (Georgia); Scalla, R. [Lab. des Xenobiotiques, INRA, Toulouse (France)

    2005-02-01

    The aim of the work is to investigate the ability of higher plants to absorb and detoxify environmental pollutants - aromatic compounds via aromatic ring cleavage. Transformation of {sup 14}C specifically labelled benzene derivatives, [1-6-{sup 14}C]-nitrobenzene, [1-6-{sup 14}C]-aniline, [1-{sup 14}C]- and [7-{sup 14}C]-benzoic acid, in axenic seedlings of maize (Zea mays L.), kidney bean (Phaseolus vulgaris L.), pea (Pisum sativum L.) and pumpkin (Cucurbita pepo L.) were studied. After penetration in plants, the above xenobiotics are transformed by oxidative or reductive reactions, conjugation with cell endogenous compounds, and binding to biopolymers. The initial stage of oxidative degradation consists in hydroxylation reactions. The aromatic ring can then be cleaved and degraded into organic acids of the Krebs cycle. Ring cleavage is accompanied by {sup 14}CO{sub 2} evolution. Aromatic ring cleavage in plants has thus been demonstrated for different xenobiotics carrying different substitutions on their benzene ring. Conjugation with low molecular peptides is the main pathway of aromatic xenobiotics detoxification. Peptide conjugates are formed both by the initial xenobiotics (except nitrobenzene) and by intermediate transformation products. The chemical nature of the radioactive fragment and the amino acid composition of peptides participating in conjugation were identified. (orig.)

  17. The future role of aromatics in refining and petrochemistry. Proceedings of the DGMK-Conference (Authors' manuscripts)

    Energy Technology Data Exchange (ETDEWEB)

    Emig, G.; Rupp, M.; Weitkamp, J. [eds.

    1999-07-01

    Topic of this conference has been the furure role of aromatics in the refinign industry. The articles deal with the following topics: Refining; legal aspects in the aromatics market; transportation fuels; dearomatization; catalytic reforming and aromatics; separation processes for aromatics; oxidation and ammoxidation of aromatics; electrophilic substitution of aromatics; hydrogenation of benzene; zeolites. (orig./sr)

  18. Decreasing polycyclic aromatic hydrocarbons emission from bitumen using alternative bitumen production process

    International Nuclear Information System (INIS)

    Rasoulzadeh, Y.; Mortazavi, S.B.; Yousefi, A.A.; Khavanin, A.

    2011-01-01

    In 1988, the National Institute for Occupational Safety and Health (NIOSH) recommended that bitumen fumes should also be considered a potential occupational carcinogen and management practices such as engineering controls should be implemented. Changing the production process of bitumen, as a source control method, was investigated in our study. For the first time, a novel alternative process was used to produce paving grade bitumen with decreased PAH emissions as well as improved bitumen performance grade (PG). Post-consumer latex and natural bitumen (NB) were used as additives to obtain 60/70 modified bitumen directly from the vacuum bottom (VB) without any need for air-blowing. The emissions were produced by a laboratory fume generation rig and were sampled and analyzed by GC-Mass and GC-FID as described in NIOSH method 5515. The PG of the resulting modified 60/70 bitumen in this study covers a wider range of climatic conditions and has higher total resistance against deformation than conventional 60/70 bitumen. The total PAH emissions from modified 60/70 bitumen (100.2619 ng/g) were decreased approximately to 50% of PAHs emitted from conventional 60/70 bitumen (197.696 ng/g). Therefore, it is possible to obtain modified bitumen with lower PAH emissions and better quality than conventional bitumen via additives and without air-blowing.

  19. SEDIMENT-ASSOCIATED REACTIONS OF AROMATIC AMINES. 2. QSAR DEVELOPMENT

    Science.gov (United States)

    The fate of aromatic amines in soils and sediments is dominated by irreversible binding through nucleophilic addition and oxidative radical coupling. Despite the common occurrence of the aromatic amine functional group in organic chemicals, the molecular properties useful for pr...

  20. Purification of water polluted with oil and sulfurous closed-ring and aromatic compounds contained in oil and oil products using bacteria relating to thiosphaera

    International Nuclear Information System (INIS)

    Kurashov, V.M.; Sakhno, T.V.; Gavrilov, V.S.; Zijatdinov, R.N.

    2005-01-01

    The intensity of natural purification (self-purification) of reservoirs polluted with oil and oil products is determined by microorganisms. Hydrocarbon-oxidizing microorganisms are constant natural constituent of biocenose in reservoirs. However, as a result of outflows, the oil and oil products concentration exceeds maximum values allowing normal vital functions of microorganisms resulting in breaking micro-biocenose suppression of vital functions of bacteria. In this regard, elective anaerobic microorganisms of Thiosphaera are worthy of notice. We found out that bacteria belonging to Thiosphaera pantotropha decomposed oil at high oil concentrations in water (at oil concentration like 1 liter of oil in 1 liter of water). And this is when aerobic microorganisms lose their vital functions at maximum concentration of 20 g of oil in 1 liter of water. To intensify the process of oil decomposition we emulsified oil with aqueous solutions of salts. Thiosphaera pantotropha are found out to decompose oil in a wide range of ratio between oil and aqueous solutions of salts: from 1:10 to 10:1. The water solutions salinity made from 20 g/l to 80 g/l. It must be noticed that, since the Thiosphaera pantotropha are elective anaerobes and decompose oil both in presence and in absence of oxygen, it is not necessary anymore to conduct the process under strictly anaerobic conditions and to supply additional oxygen. This makes it possible to simplify the process of biodegradation of oil and to make this process practically more feasible and economically more profitable being compared to the processes based on the use of other species of bacteria. We found out that Thiosphaera decompose sulfurous closed-ring and aromatic compounds in oil which are chemically and thermally stable and can be hardly decomposed, and possess extremely poisonous properties, as well. The use of microorganisms of Thiosphaera pantotropha allows to purify waters polluted with oil and oil products both during

  1. Determination of 15 polycyclic aromatic hydrocarbons in aquatic products by solid-phase extraction and GC-MS.

    Science.gov (United States)

    Liu, Qiying; Guo, Yuanming; Sun, Xiumei; Hao, Qing; Cheng, Xin; Zhang, Lu

    2018-02-22

    We propose a method for the simultaneous determination of 15 kinds of polycyclic aromatic hydrocarbons in marine samples (muscle) employing gas chromatography with mass spectrometry after saponification with ultrasound-assisted extraction and solid-phase extraction. The experimental conditions were optimized by the response surface method. In addition, the effects of different lyes and extractants on polycyclic aromatic hydrocarbons extraction were discussed, and saturated sodium carbonate was first used as the primary saponification reaction and extracted with 10 mL of ethyl acetate and secondly 1 mol/L of sodium hydroxide and 10 mL of n-hexane were used to achieve better results. The average recovery was 67-112%. Satisfactory data showed that the method has good reproducibility with a relative standard deviation of <13%. The detection limits of polycyclic aromatic hydrocarbons were 0.02-0.13 ng/g. Compared with other methods, this method has the advantages of simple pretreatment, low solvent consumption, maximum polycyclic aromatic hydrocarbons extraction, the fast separation speed, and the high extraction efficiency. It is concluded that this method meets the batch processing requirements of the sample and can also be used to determine polycyclic aromatic hydrocarbons in other high-fat (fish, shrimp, crab, shellfish) biological samples. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  2. Cholesterol oxidation products and their biological importance

    DEFF Research Database (Denmark)

    Kulig, Waldemar; Cwiklik, Lukasz; Jurkiewicz, Piotr

    2016-01-01

    The main biological cause of oxysterols is the oxidation of cholesterol. They differ from cholesterol by the presence of additional polar groups that are typically hydroxyl, keto, hydroperoxy, epoxy, or carboxyl moieties. Under typical conditions, oxysterol concentration is maintained at a very low...... and precisely regulated level, with an excess of cholesterol. Like cholesterol, many oxysterols are hydrophobic and hence confined to cell membranes. However, small chemical differences between the sterols can significantly affect how they interact with other membrane components, and this in turn can have...

  3. Simultaneous determination of 9 heterocyclic aromatic amines in pork products by liquid chromatography coupled with triple quadrupole tandem mass spectrometry

    Science.gov (United States)

    Shen, X. C.; Zhang, Y. L.; Cui, Y. Q.; Xu, L. Y.; Li, X.; Qi, J. H.

    2017-07-01

    Heterocyclic aromatic amines (HAAs) are potent mutagens that formed at high temperature in cooked, protein-rich food. Owing to their frequent intake, an accurate method is essential to access human health risk of HAAs exposure through detecting these compounds in various heat-treated meat products. In this study, a liquid chromatography-electrospray tandem mass spectrometry (LC--ESI-MS/MS) method was developed to perform the determination of 9 mutagenic heterocyclic amines (HAAs) in meat samples with multiple reaction monitoring (MRM) mode. Ultrasound assisted extraction and diatomaceous earth was employed to extract HAAs from food samples, and the analytes were purified and enriched using tandem solid phase extraction, with propyl sulfonic acid coupled to a C18 cartridge. Two parameters, extraction time and eluent, were carefully optimized to improve the extraction and purification efficiency. The LC separation was carried out using a Zorbax SB-C18 (3.5 μm particle size, 2.1 × 150 mm i.d.) column and optimized some parameters, such as pH, concentration and volume. Under the optimal experimental conditions, recoveries ranged from 52.97% to 97.11% with good quality parameters: limit of detection values between 0.02 and 0.24 ng mL-1, linearity (R2>0.998), and run-to-run and day-to-day precisions lower than 9.81% achieved. To evaluate the performance of the method in high throughput analysis of complex meat samples, the LC-MS/MS method was applied to the analysis of HAAs in three food samples, and the results demonstrated that the method can be used for the trace determination of HAAs in pork samples.

  4. Effect of incorporating graphene oxide and surface imprinting on polysulfone membranes on flux, hydrophilicity and rejection of salt and polycyclic aromatic hydrocarbons from water

    Science.gov (United States)

    Kibechu, Rose Waithiegeni; Ndinteh, Derek Tantoh; Msagati, Titus Alfred Makudali; Mamba, Bhekie Briliance; Sampath, S.

    2017-08-01

    We report a significant enhancement of hydrophillity of polysulfone (Psf) membranes after modification with graphene oxide (GO) as a filler followed by surface imprinting on the surface of GO/Psf composite imprinted membranes (CIMs). The surface imprinting on the GO-Psf membrane was employed in order to enhance its selectivity towards polycyclic aromatic hydrocarbons (PAHs) in water. The CIMs were prepared through a process of phase inversion of a mixture of graphene oxide and polysulfone (Psf) in N-methylpyrrolidone (NMP). Fourier-transform spectroscopy (FT-IR) of the imprinted showed new peaks at 935 cm-1 and 1638 cm-1 indicating success in surface imprinting on the GO-Psf membrane. The CIM also showed improvement in flux from 8.56 LM-2 h-1 of unmodified polysulfone membrane to 15.3 LM-2 h-1 in the CIM, salt rejection increased from 57.2 ± 4.2% of polysulfone membrane to 76 ± 4.5%. The results obtained from the contact angle measurements showed a decrease with increase in GO content from 72 ± 2.7% of neat polysulfone membrane to 62.3 ± 2.1% of CIM indicating an improvement in surface hydrophilicity. The results from this study shows that, it is possible to improve the hydrophilicity of the membranes without affecting the performance of the membranes.

  5. Sensitive electrochemical sensing for polycyclic aromatic amines based on a novel core-shell multiwalled carbon nanotubes@ graphene oxide nanoribbons heterostructure.

    Science.gov (United States)

    Zhu, Gangbing; Yi, Yinhui; Han, Zhixiang; Wang, Kun; Wu, Xiangyang

    2014-10-03

    Being awfully harmful to the environment and human health, the qualitative and quantitative determinations of polycyclic aromatic amines (PAAs) are of great significance. In this paper, a novel core-shell heterostructure of multiwalled carbon nanotubes (MWCNTs) as the core and graphene oxide nanoribbons (GONRs) as the shell (MWCNTs@GONRs) was produced from longitudinal partially unzipping of MWCNTs side walls using a simple wet chemical strategy and applied for electrochemical determination of three kinds of PAAs (1-aminopyrene (1-AP), 1-aminonaphthalene and 3,3'-diaminobiphenyl). Scanning electron microscopy, transmission electron microscopy, Fourier transform infrared spectroscopy, Raman spectroscopy, thermogravimetric analysis and electrochemical methods were used to characterize the as-prepared MWCNTs@GONRs. Due to the synergistic effects from MWCNTs and GONRs, the oxidation currents of PAAs at the MWCNTs@GONRs modified glassy carbon (GC) electrode are much higher than that at the MWCNTs/GC, graphene/GC and bare GC electrodes. 1-AP was used as the representative analyte to demonstrate the sensing performance of the MWCNTs@GONRs/GC electrode, and the proposed modified electrode has a linear response range of 8.0-500.0 nM with a detection limit of 1.5 nM towards 1-AP. Copyright © 2014 Elsevier B.V. All rights reserved.

  6. Sensitive electrochemical sensing for polycyclic aromatic amines based on a novel core–shell multiwalled carbon nanotubes@ graphene oxide nanoribbons heterostructure

    Energy Technology Data Exchange (ETDEWEB)

    Zhu, Gangbing, E-mail: zhgb1030@ujs.edu.cn [School of the Environment and Safety Engineering, Jiangsu University, Zhenjiang 212013 (China); Yi, Yinhui; Han, Zhixiang [School of the Environment and Safety Engineering, Jiangsu University, Zhenjiang 212013 (China); Wang, Kun [School of Chemistry and Chemical Engineering, Jiangsu University, Zhenjiang 212013 (China); Wu, Xiangyang, E-mail: wuxy@ujs.edu.cn [School of the Environment and Safety Engineering, Jiangsu University, Zhenjiang 212013 (China)

    2014-10-03

    Highlights: • A core–shell heterostructure MWCNTs@GONRs was produced from unzipping MWCNTs. • A new electrochemical sensor for PAAs was developed based on MWCNTs@GONRs hybrids. • The sensor shows good analytical performance for PAAs detection. - Abstract: Being awfully harmful to the environment and human health, the qualitative and quantitative determinations of polycyclic aromatic amines (PAAs) are of great significance. In this paper, a novel core–shell heterostructure of multiwalled carbon nanotubes (MWCNTs) as the core and graphene oxide nanoribbons (GONRs) as the shell (MWCNTs@GONRs) was produced from longitudinal partially unzipping of MWCNTs side walls using a simple wet chemical strategy and applied for electrochemical determination of three kinds of PAAs (1-aminopyrene (1-AP), 1-aminonaphthalene and 3,3′-diaminobiphenyl). Scanning electron microscopy, transmission electron microscopy, Fourier transform infrared spectroscopy, Raman spectroscopy, thermogravimetric analysis and electrochemical methods were used to characterize the as-prepared MWCNTs@GONRs. Due to the synergistic effects from MWCNTs and GONRs, the oxidation currents of PAAs at the MWCNTs@GONRs modified glassy carbon (GC) electrode are much higher than that at the MWCNTs/GC, graphene/GC and bare GC electrodes. 1-AP was used as the representative analyte to demonstrate the sensing performance of the MWCNTs@GONRs/GC electrode, and the proposed modified electrode has a linear response range of 8.0–500.0 nM with a detection limit of 1.5 nM towards 1-AP.

  7. Sensitive electrochemical sensing for polycyclic aromatic amines based on a novel core–shell multiwalled carbon nanotubes@ graphene oxide nanoribbons heterostructure

    International Nuclear Information System (INIS)

    Zhu, Gangbing; Yi, Yinhui; Han, Zhixiang; Wang, Kun; Wu, Xiangyang

    2014-01-01

    Highlights: • A core–shell heterostructure MWCNTs@GONRs was produced from unzipping MWCNTs. • A new electrochemical sensor for PAAs was developed based on MWCNTs@GONRs hybrids. • The sensor shows good analytical performance for PAAs detection. - Abstract: Being awfully harmful to the environment and human health, the qualitative and quantitative determinations of polycyclic aromatic amines (PAAs) are of great significance. In this paper, a novel core–shell heterostructure of multiwalled carbon nanotubes (MWCNTs) as the core and graphene oxide nanoribbons (GONRs) as the shell (MWCNTs@GONRs) was produced from longitudinal partially unzipping of MWCNTs side walls using a simple wet chemical strategy and applied for electrochemical determination of three kinds of PAAs (1-aminopyrene (1-AP), 1-aminonaphthalene and 3,3′-diaminobiphenyl). Scanning electron microscopy, transmission electron microscopy, Fourier transform infrared spectroscopy, Raman spectroscopy, thermogravimetric analysis and electrochemical methods were used to characterize the as-prepared MWCNTs@GONRs. Due to the synergistic effects from MWCNTs and GONRs, the oxidation currents of PAAs at the MWCNTs@GONRs modified glassy carbon (GC) electrode are much higher than that at the MWCNTs/GC, graphene/GC and bare GC electrodes. 1-AP was used as the representative analyte to demonstrate the sensing performance of the MWCNTs@GONRs/GC electrode, and the proposed modified electrode has a linear response range of 8.0–500.0 nM with a detection limit of 1.5 nM towards 1-AP

  8. Production and characterization of quality gadolinium oxide nanoparticles

    International Nuclear Information System (INIS)

    Hazarika, Samiran; Mohanta, Dambarudhar

    2013-01-01

    Rare earth system Gadolinium (Gd), in either pure form or oxide form, is highly stable against environmental attack. It has immense potential as a contrast agent in magnetic resonance imaging (MRI) devices. Being mechanically and thermally stable it is always difficult to obtain Gd 2 O 3 nanopowders directly from its bulk counterpart using conventional top-down approach. Recently, we have reported production of Gd 2 O 3 nanopowders by first converting bulk Gd 2 O 3 into a nitrate compound and subsequently reduced into a hydroxide product and finally to the oxide product (nanopowder form)

  9. Laboratory Studies of Stabilities of Heterocyclic Aromatic Molecules: Suggested Gas Phase Ion-Molecule Routes to Production in Interstellar Gas Clouds

    Science.gov (United States)

    Adams, Nigel G.; Fondren, L. Dalila; McLain, Jason L.; Jackson, Doug M.

    2006-01-01

    Several ring compounds have been detected in interstellar gas clouds, ISC, including the aromatic, benzene. Polycyclic aromatic hydrocarbons, PAHs, have been implicated as carriers of diffuse interstellar bands (DIBs) and unidentified infrared (UIR) bands. Heterocyclic aromatic rings of intermediate size containing nitrogen, possibly PreLife molecules, were included in early searches but were not detected and a recent search for Pyrimidine was unsuccessful. Our laboratory investigations of routes to such molecules could establish their existence in ISC and suggest conditions under which their concentrations would be maximized thus aiding the searches. The stability of such ring compounds (C5H5N, C4H4N2, C5H11N and C4H8O2) has been tested in the laboratory using charge transfer excitation in ion-molecule reactions. The fragmentation paths, including production of C4H4(+), C3H3N(+) and HCN, suggest reverse routes to the parent molecules, which are presently under laboratory investigation as production sources.

  10. Super oxidation and solidification of organic solvents, polycyclic aromatic hydrocarbons and pesticides at an abandoned chemical factory site

    Energy Technology Data Exchange (ETDEWEB)

    Yao, Kevin; Xu, Paul [Suntime Remediation Company, Changzhou, Jiangsu (China); Loo, Walter [Environment and Technology Services, 1323 Horizon Lane, Patterson, CA 95363 (United States)

    2013-07-01

    Large quantities of organic chemical such as VOCs, SVOCs and POPs were found in the soil of land at an abandoned Chemical Plant. Technology of super oxidation was applied to the soil for cleanup. Fenton process was utilized to treat soil contaminated heavily by BHC, benzene, chlorobenzene, dichlorobenzene, hexachlorobenzene, dichloroethane, dichloropropane, trichlorobenzene and dichloroether, etc. Super oxidation was coupled with method of stabilization for this case to enhance the remediation effect, which proved to be successful. Concentration of concerned pollutants was brought down below the national regulation level by approximately 8 folds. To make the treated soil strong and effective layer preventing pollutants breaking through, Iron powder was mixed in the soil, forming PBR (Permeable Barrier Reactor), to lower the risk to human health. The site after enhanced super oxidation above was totally safe to be developed into a residential community and/or commercial area. (authors)

  11. Aromatic graphene

    Energy Technology Data Exchange (ETDEWEB)

    Das, D. K., E-mail: gour.netai@gmail.com [Department of Metallurgical and Material Science Engineering, National Institute of Technology Durgapur-713209, West Bengal (India); Sahoo, S., E-mail: sukadevsahoo@yahoo.com [Department of Physics, National Institute of Technology Durgapur-713209, West Bengal (India)

    2016-04-13

    In recent years graphene attracts the scientific and engineering communities due to its outstanding electronic, thermal, mechanical and optical properties and many potential applications. Recently, Popov et al. [1] have studied the properties of graphene and proved that it is aromatic but without fragrance. In this paper, we present a theory to prepare graphene with fragrance. This can be used as scented pencils, perfumes, room and car fresheners, cosmetics and many other useful household substances.

  12. Aromatic graphene

    International Nuclear Information System (INIS)

    Das, D. K.; Sahoo, S.

    2016-01-01

    In recent years graphene attracts the scientific and engineering communities due to its outstanding electronic, thermal, mechanical and optical properties and many potential applications. Recently, Popov et al. [1] have studied the properties of graphene and proved that it is aromatic but without fragrance. In this paper, we present a theory to prepare graphene with fragrance. This can be used as scented pencils, perfumes, room and car fresheners, cosmetics and many other useful household substances.

  13. Production of natural fragrance aromatic acids by coexpression of trans-anethole oxygenase and p-anisaldehyde dehydrogenase genes of Pseudomonas putida JYR-1 in Escherichia coli.

    Science.gov (United States)

    Han, Dongfei; Kurusarttra, Somwang; Ryu, Ji-Young; Kanaly, Robert A; Hur, Hor-Gil

    2012-12-05

    A gene encoding p-anisaldehyde dehydrogenase (PAADH), which catalyzes the oxidation of p-anisaldehyde to p-anisic acid, was identified to be clustered with the trans-anethole oxygenase (tao) gene in Pseudomonas putida JYR-1. Heterologously expressed PAADH in Escherichia coli catalyzed the oxidation of vanillin, veratraldehyde, and piperonal to the corresponding aromatic acids vanillic acid, veratric acid, and piperonylic acid, respectively. Coexpression of trans-anethole oxygenase (TAO) and PAADH in E. coli also resulted in the successful transformation of trans-anethole, isoeugenol, O-methyl isoeugenol, and isosafrole to p-anisic acid, vanillic acid, veratric acid, and piperonylic acid, respectively, which are compounds found in plants as secondary metabolites. Because of the relaxed substrate specificity and high transformation rates by coexpressed TAO and PAADH in E. coli , the engineered strain has potential to be applied in the fragrance industry.

  14. Selective Oxidation of Lignin Model Compounds.

    Science.gov (United States)

    Gao, Ruili; Li, Yanding; Kim, Hoon; Mobley, Justin K; Ralph, John

    2018-05-02

    Lignin, the planet's most abundant renewable source of aromatic compounds, is difficult to degrade efficiently to welldefined aromatics. We developed a microwave-assisted catalytic Swern oxidation system using an easily prepared catalyst, MoO 2 Cl 2 (DMSO) 2 , and DMSO as the solvent and oxidant. It demonstrated high efficiency in transforming lignin model compounds containing the units and functional groups found in native lignins. The aromatic ring substituents strongly influenced the selectivity of β-ether phenolic dimer cleavage to generate sinapaldehyde and coniferaldehyde, monomers not usually produced by oxidative methods. Time-course studies on two key intermediates provided insight into the reaction pathway. Owing to the broad scope of this oxidation system and the insight gleaned with regard to its mechanism, this strategy could be adapted and applied in a general sense to the production of useful aromatic chemicals from phenolics and lignin. © 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  15. Fact and Fiction of Nitrous Oxide Production By Nitrification

    Science.gov (United States)

    Stein, L. Y.; Kozlowski, J.; Stieglmeier, M.; Klotz, M. G.; Schleper, C.

    2014-12-01

    An accepted dogma in nitrification research is that ammonia-oxidizing bacteria (AOB) produce a modicum of nitrous oxide (N2O) during nitritation via incomplete oxidation of hydroxylamine, and substantially more at low oxygen concentrations via nitrifier denitrification.The nitrifier denitrification pathway involves the reduction of nitrite to N2O via nitric oxide and was thought to require activities of a copper-containing nitrite reductase (NirK) and nitric oxide reductase (NorB); inventory encoded in most, but not all AOB genome sequences. The discovery of nirK genes in ammonia-oxidizing Thaumarchaeota (AOA) resulted in a slew of publications stating that AOA must also perform nitrifier denitrification and, due to their high abundance, must control the majority of nitrification-linked N2O emissions. Prior to a publication by Stieglmeier et al. (2014), which definitively showed a lack of nitrifier denitrification by two axenic AOA cultures, other researchers relied on enrichment cultures, negative data, and heavy inferencing without direct demonstration of either a functional pathway or involvement of specific genes or enzymes. AOA genomes lack recognizable nitric oxide reductases and thermophilic AOA also lack nirK genes. Physiological and microrespirometry experiments with axenic AOB and AOA cultures allowed us to demonstrate that: 1) AOB produce N2O via nitrifier denitrification even though some lack annotated nirK and/or norB genes; 2) nitrifier denitrification by AOB is reliant on nitric oxide but ammonia oxidation is not; 3) ammonia oxidation by AOA is reliant on production of nitric oxide; 4) AOA are incapable of generating N2O via nitrifier denitrification; 5) N2O production by AOA is from chemical interactions between NO and media components, most likely not by enzyme activity. Our results reveal operation of different N oxide transformation pathways in AOB and AOA governed by different environmental controls and involving different mechanisms of N2O

  16. Identifying breakthrough technologies for the production of basic chemicals. A long term view on the sustainable production of ammonia, olefins and aromatics in the European region

    Energy Technology Data Exchange (ETDEWEB)

    Benner, J.; Van Lieshout, M.; Croezen, H.

    2012-01-15

    The European Commission's Roadmap for a competitive and low carbon economy in 2050 indicates that greenhouse gas emissions (GHG) in all sectors should be significantly reduced to meet the European Union (EU) objective of 80 to 95% greenhouse gas emission reductions by 2050 compared to 1990 levels. The European Commission indicated in the Roadmap that the EU's industrial sectors should reduce emissions by 83 to 87% domestically by 2050 compared to 1990 levels. The objective of this study is to explore breakthrough abatement technologies in three processes in the European chemical industry that can considerably contribute to achieving the required greenhouse gas emission reductions. In this context we have assessed the processes for the production of: (1) Ammonia; (2) Olefins; (3) Aromatics (BTX). For all three processes possible breakthrough abatement technologies were found, allowing for reductions in GHG emissions varying between 50 and 100% compared to the conventional processes. Our finding regarding the chemical industry and our earlier findings regarding options in the steel, cement and pulp and paper industries show that promising breakthrough abatement technologies are available for European energy-intensive industries to contribute to a low-carbon economy. However, large scale deployment requires an integrated EU industry and energy policy allowing for a resource efficient and sustainable use of available biomass, CCS storage capacity and renewable energy capacity.

  17. Identifying breakthrough technologies for the production of basic chemicals. A long term view on the sustainable production of ammonia, olefins and aromatics in the European region

    Energy Technology Data Exchange (ETDEWEB)

    Benner, J.; Van Lieshout, M.; Croezen, H.

    2012-01-15

    The European Commission's Roadmap for a competitive and low carbon economy in 2050 indicates that greenhouse gas emissions (GHG) in all sectors should be significantly reduced to meet the European Union (EU) objective of 80 to 95% greenhouse gas emission reductions by 2050 compared to 1990 levels. The European Commission indicated in the Roadmap that the EU's industrial sectors should reduce emissions by 83 to 87% domestically by 2050 compared to 1990 levels. The objective of this study is to explore breakthrough abatement technologies in three processes in the European chemical industry that can considerably contribute to achieving the required greenhouse gas emission reductions. In this context we have assessed the processes for the production of: (1) Ammonia; (2) Olefins; (3) Aromatics (BTX). For all three processes possible breakthrough abatement technologies were found, allowing for reductions in GHG emissions varying between 50 and 100% compared to the conventional processes. Our finding regarding the chemical industry and our earlier findings regarding options in the steel, cement and pulp and paper industries show that promising breakthrough abatement technologies are available for European energy-intensive industries to contribute to a low-carbon economy. However, large scale deployment requires an integrated EU industry and energy policy allowing for a resource efficient and sustainable use of available biomass, CCS storage capacity and renewable energy capacity.

  18. Exposure to polycyclic aromatic hydrocarbons, arsenic and environmental tobacco smoke, nutrient intake, and oxidative stress in Japanese preschool children.

    Science.gov (United States)

    Mori, Takuya; Yoshinaga, Jun; Suzuki, Kei; Mizoi, Miho; Adachi, Shu-Ichi; Tao, Hiroaki; Nakazato, Tetsuya; Li, Yun-Shan; Kawai, Kazuaki; Kasai, Hiroshi

    2011-07-01

    The association between oxidative stress and exposure to environmental chemicals was assessed in a group of Japanese preschool children. The concentrations of 8-hydroxy-2'-deoxyguanosine (8-OHdG), 1-hydroxypyrene (1-OHP), inorganic arsenic (iAs) and monomethylarsonic acid (MMA), and cotinine in spot urine samples, collected from 134 children (3-6 yrs) from a kindergarten in Kanagawa, Japan, were measured as biomarkers of oxidative stress or exposure to environmental chemicals. For 76 subjects of the 134, intakes of anti-oxidant nutrients (vitamins A, C, and E, manganese, copper, zinc and selenium (Se)) were estimated from a food consumption survey carried out 2-4 weeks after urine sampling and by urine analysis (Se). The median (min-max) creatinine-corrected concentrations of urinary biomarkers were 4.45 (1.98-12.3), 0.127 (0.04-2.41), 4.78 (1.18-12.7), and 0.62 (iAs+MMA, and cotinine, respectively. Multiple regression analysis was carried out using 8-OHdG concentration as a dependent variable and urinary biomarkers of exposure and Se intake, intakes of vitamins and biological attributes of the subjects as independent variables. To explain 8-OHdG concentrations, intake of vitamin A and age were significant variables with negative coefficients, while 1-OHP concentration had a positive coefficient. These results indicated that oxidative stress of children is affected by chemical exposure at environmental levels, by nutrient intake and by physiological factors in a complex manner. On the other hand, unstable statistical results due to sub-grouping of subject, based on the availability of food consumption data, were found: the present results should further be validated by future studies with suitable research design. Copyright © 2011 Elsevier B.V. All rights reserved.

  19. Role of GSTT1 deletion in DNA oxidative damage by exposure to polycyclic aromatic hydrocarbons in humans

    Czech Academy of Sciences Publication Activity Database

    Garte, S.; Taioli, E.; Popov, T.; Kalina, I.; Šrám, Radim; Farmer, P.

    2007-01-01

    Roč. 120, - (2007), s. 2499-2503 ISSN 0020-7136 Grant - others:EU(GB) 2000-00091 Institutional research plan: CEZ:AV0Z50390512 Source of funding: R - rámcový projekt EK Keywords : metabolic polymorphism * GSTT1 genotype * oxidative DNA damage Subject RIV: DN - Health Impact of the Environment Quality Impact factor: 4.555, year: 2007

  20. Triplet-State Dissolved Organic Matter Quantum Yields and Lifetimes from Direct Observation of Aromatic Amine Oxidation.

    Science.gov (United States)

    Schmitt, Markus; Erickson, Paul R; McNeill, Kristopher

    2017-11-21

    Excited triplet state chromophoric dissolved organic matter ( 3 CDOM*) is a short-lived mixture of excited-state species that plays important roles in aquatic photochemical processes. Unlike the study of the triplet states of well-defined molecules, which are amenable to transient absorbance spectroscopy, the study of 3 CDOM* is hampered by it being a complex mixture and its low average intersystem crossing quantum yield (Φ ISC ). This study is an alternative approach to investigating 3 CDOM* using transient absorption laser spectroscopy. The radical cation of N,N,N',N'-tetramethyl-p-phenylenediamine (TMPD), formed through oxidation by 3 CDOM*, was directly observable by transient absorption spectroscopy and was used to probe basic photophysical properties of 3 CDOM*. Quenching and control experiments verified that TMPD •+ was formed from 3 CDOM* under anoxic conditions. Model triplet sensitizers with a wide range of excited triplet state reduction potentials and CDOM oxidized TMPD at near diffusion-controlled rates. This gives support to the idea that a large cross-section of 3 CDOM* moieties are able to oxidize TMPD and that the complex mixture of 3 CDOM* can be simplified to a single signal. Using the TMPD •+ transient, the natural triplet lifetime and Φ ISC for different DOM isolates and natural waters were quantified; values ranged from 12 to 26 μs and 4.1-7.8%, respectively.

  1. Session 4: Study of alkyl-aromatics hydrodealkylation reaction to orient the production of benzene from the catalytic reforming process

    Energy Technology Data Exchange (ETDEWEB)

    Toppi, S.; Thomas, C.; Sayag, C.; Brodzki, D.; Djega-Mariadassou, G. [Universite Pierre et Marie Curie, Lab. de Reactivite de Surface, UMR CNRS 7609, 75 - Paris (France); Toppi, S.; Travers, C.; Le Peltier, F. [Institut Francais du Petrole (IFP), 92 - Rueil-Malmaison (France)

    2004-07-01

    Due to more stringent environmental constraints, the benzene content in the gasoline decreases regularly and has been fixed to 1% since January 2001. In the same time, the demand in aromatics, benzene, toluene, and xylenes, for the petrochemistry continuously increases. The aim of this work is to study the hydrodealkylation reactions and particularly the benzene formation under reforming operating conditions, with the bifunctional industrial catalyst. It is, therefore, of great importance to determine the role of each function of the catalyst involved in the benzene production in order to orient the reaction by modification of the catalyst. n-propylbenzene transformation was investigated on each family of model catalysts and allowed us to propose a detailed scheme for the reaction on acidic and metallic sites. The identified reactions are: - on metallic sites: dehydrogenation, cyclisation and hydrogenolysis A detailed reaction scheme for this transformation has already been proposed involving the formation of cyclisation products and the existence of a common reactive adsorbate for the indene compounds and ethylbenzene; - on acidic sites: dehydrogenation, isomerization and cracking. The study of the cracking reactions coupled with measurements of the acidity of the catalyst, shows that benzene is the preferentially formed cracking product, on the Broensted sites of the catalyst, through a carbo-cationic mechanism. Conversely, ethylbenzene and toluene are formed through a 'radical' mechanism over the Lewis acid sites of alumina. As far as the cracking reaction leading to benzene is concerned, two compulsory steps were pointed out: the first one is the isomerization of n-propylbenzene to iso-propylbenzene, and the second one is the cracking of iso-propylbenzene into benzene. The increase of strong Broensted acidity over model acidic catalysts, has been correlated with a strong increase of the benzene formation rate, emphasizing the role of strong Broensted

  2. A nanocomposite disk prepared from reduced graphene oxide and gold nanoparticles for the preconcentration of heterocyclic aromatic amines prior to their determination by HPLC

    International Nuclear Information System (INIS)

    Tan, Connieal; Wang, Yiru; Deng, Zhuo; Xu, Na; Song, Xinhong; Liu, Haihong; Rong, Mingcong; Chen, Xi

    2014-01-01

    We report on a preconcentration disk for the determination of trace amounts of heterocyclic aromatic amines (HAAs) in the groups of quinoline and quinoxaline congeners as possible human carcinogens. The disk is based on nanocomposite (NC) prepared from graphene oxide as the precursor and from gold nanoparticles that act as building blocks to form a three-dimensional NC. If deposited in the sampling valve of a HPLC system, the material displays excellent extraction capability for HAAs owing to its large surface and π-π stacking interaction. Following an optimization of the extraction parameters, the method was successfully applied to the simultaneous determination of polar HAAs in meat samples with detection limit of 0.09 to 0.16 ng g −1 and recoveries of 69.5 to 122.7 %. The disk was used in more than 150 subsequent preconcentration cycles without obvious loss of the absorption capability. The results reveal that this new NC represents an excellent sorbent for purposes of preconcentration. (author)

  3. Phytic acid-stabilized super-amphiphilic Fe3O4-graphene oxide for extraction of polycyclic aromatic hydrocarbons from vegetable oils.

    Science.gov (United States)

    Ji, Wenhua; Zhang, Mingming; Duan, Wenjuan; Wang, Xiao; Zhao, Hengqiang; Guo, Lanping

    2017-11-15

    Phytic acid-stabilized Fe 3 O 4 -graphene oxide (GOPA@Fe 3 O 4 ) was assembled by microwave-enhanced hydrothermal synthesis and super-amphipathicity was demonstrated by measurement of dynamic oil and water contact angles. GOPA@Fe 3 O 4 was used as a sorbent for enrichment of eight polycyclic aromatic hydrocarbons (PAHs) from vegetable oils by magnetic solid-phase extraction (MSPE). The extraction-desorption factors were systematically investigated and, under optimum conditions, the super-amphiphilic sorbent achieved wide linear ranges (0.2-200ngg -1 ), satisfactory precision (3.44-6.64% for intra-day and 5.39-8.41% for inter-day) and low limits of detection (LODs, 0.06-0.15ngg -1 ) for PAHs. Excellent recoveries (85.6-102.3%) for spiked PAHs were obtained with genuine vegetable oil samples. These results indicate that MSPE using GOPA@Fe 3 O 4 as the sorbent, coupled with high performance liquid chromatography (HPLC), is an efficient and simple method for the detection of low concentrations of PAHs in vegetable oils. Copyright © 2017 Elsevier Ltd. All rights reserved.

  4. Reduced Graphene Oxide-Hybridized Polymeric High-Internal Phase Emulsions for Highly Efficient Removal of Polycyclic Aromatic Hydrocarbons from Water Matrix.

    Science.gov (United States)

    Huang, Yipeng; Zhang, Wenjuan; Ruan, Guihua; Li, Xianxian; Cong, Yongzheng; Du, Fuyou; Li, Jianping

    2018-03-27

    Reduced graphene oxide (RGO)-hybridized polymeric high-internal phase emulsions (RGO/polyHIPEs) with an open-cell structure and hydrophobicity have been successfully prepared using 2-ethylhexyl acrylate and ethylene glycol dimethacrylate as the monomer and the cross-linker, respectively. The adsorption mechanism and performance of this RGO/polyHIPEs to polycyclic aromatic hydrocarbons (PAHs) were investigated. Adsorption isotherms of PAHs on RGO/polyHIPEs show that the saturated adsorption capacity is 47.5 mg/g and the equilibrium time is 8 h. Cycling tests show that the adsorption capacity of RGO/polyHIPEs remains stable in 10 adsorption-desorption cycles without observable structure change in RGO/polyHIPEs. Moreover, the PAH residues in water samples after being purified by RGO/polyHIPEs are lower than the limit values in drinking water set by the European Food Safety Authority. These results demonstrate that the RGO/polyHIPEs have great potentiality in PAH removal and water purification.

  5. Corrosion-product transport, oxidation state and remedial measures

    International Nuclear Information System (INIS)

    Sawicki, J.A.; Brett, M.E.; Tapping, R.L.

    1998-01-01

    The issues associated with monitoring and controlling corrosion-product transport (CPT) in the balance-of-plant (BOP) and steam generators (SG) of CANDU stations are briefly reviewed. The efforts are focused on minimizing corrosion of carbon steel, which is used extensively in the CANDU primary and secondary systems. Emphasis is placed on the corrosion-product oxidation state as a monitor of water chemistry effectiveness, and as a monitor of system corrosion effects. The discussion is based mostly on the results and observations from Ontario Hydro plants, and their comparisons with PWRs. The effects of low oxygen and elevated hydrazine chemistry are reviewed, as well as the effects of lay-up and various start-up conditions. Progress in monitoring electrochemical potential (ECP) at Ontario Hydro plants and its relationship to the oxidation state of corrosion products is reviewed. Observations on corrosion-product transport on the primary side of steam generators are also discussed. (author)

  6. A nanocomposite consisting of silica-coated magnetite and phenyl-functionalized graphene oxide for extraction of polycyclic aromatic hydrocarbon from aqueous matrices.

    Science.gov (United States)

    Mahpishanian, Shokouh; Sereshti, Hassan; Ahmadvand, Mohammad

    2017-05-01

    In this study, graphene oxide was covalently immobilized on silica-coated magnetite and then modified with 2-phenylethylamine to give a nanocomposite of type Fe 3 O 4 @SiO 2 @GO-PEA that can be applied to the magnetic solid-phase extraction of polycyclic aromatic hydrocarbons (PAHs) from water samples. The resulting microspheres (Fe 3 O 4 @SiO 2 @GO-PEA) were characterized by Fourier transform-infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), CHNS elemental analysis, and vibrating sample magnetometry (VSM) techniques. The adsorbent possesses the magnetic properties of Fe 3 O 4 nanoparticles that allow them easily to be separated by an external magnetic field. They also have the high specific surface area of graphene oxide which improves adsorption capacity. Desorption conditions, extraction time, amount of adsorbent, salt concentration, and pH were investigated and optimized. Following desorption, the PAHs were quantified by gas chromatography with flame ionization detection (GC-FID). The limits of detection (at an S/N ratio of 3) were achieved from 0.005 to 0.1μg/L with regression coefficients (R 2 ) higher than 0.9954. The relative standard deviations (RSDs) were below 5.8% (intraday) and 6.2% (inter-day), respectively. The method was successfully applied to the analysis of PAHs in environmental water samples where it showed recoveries in the range between 71.7% and 106.7% (with RSDs of 1.6% to 8.4%, for n=3). The results indicated that the Fe 3 O 4 @SiO 2 @GO-PEA microspheres had a great promise to extraction of PAHs from different water samples. Copyright © 2016. Published by Elsevier B.V.

  7. Molecular epidemiology studies of carcinogenic environmental pollutants. Effects of polycyclic aromatic hydrocarbons (PAHs) in environmental pollution on exogenous and oxidative DNA damage.

    Science.gov (United States)

    Farmer, Peter B; Singh, Rajinder; Kaur, Balvinder; Sram, Radim J; Binkova, Blanka; Kalina, Ivan; Popov, Todor A; Garte, Seymour; Taioli, Emanuela; Gabelova, Alena; Cebulska-Wasilewska, Antonina

    2003-11-01

    Exposure to high levels of environmental air pollution is known to be associated with an increased carcinogenic risk. The individual contribution to this risk derived from specific carcinogenic chemicals within the complex mixture of air pollution is less certain, but may be explored by the use of molecular epidemiological techniques. Measurements of biomarkers of exposure, of effect and of susceptibility provide information of potential benefit for epidemiological and cancer risk assessment. The application of such techniques has been mostly concerned in the past with the carcinogenic polycyclic aromatic hydrocarbons (c-PAHs) that are associated with particulate matter in air pollution, and has showed clear evidence of genotoxic effects, such as DNA adducts, chromosome aberrations (CA) and ras oncogene overexpression, in environmentally exposed Czech and Polish populations. We are currently extending these studies by an investigation of populations exposed to environmental pollution in three European countries, Czech Republic, Slovak Republic and Bulgaria. This pays particular attention to PAHs, but also investigates the extent of radically induced (oxidative) DNA damage in the exposed populations. Policemen, bus drivers and controls, who carried personal monitors to determine their exposures to PAHs have been studied, and blood and urine were collected. Antioxidant and dietary status were assessed in these populations. Stationary monitors were also used for ambient air monitoring. Amongst the parameters studied in the biological samples were: (a) exposure biomarkers, such as PAH adducts with DNA, p53 and p21(WAF1) protein levels, (b) oxidative DNA damage, (c) the biological effect of the exposure by measurement of chromosome damage by fluorescence in situ hybridisation (FISH) or conventional methods, and (d) polymorphisms in carcinogen metabolising and DNA repair enzymes. Repair ability was also measured by the Comet assay. In vitro systems are being evaluated to

  8. The effects of heavy metals and their interactions with polycyclic aromatic hydrocarbons on the oxidative stress among coke-oven workers

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Tian; Feng, Wei; Kuang, Dan; Deng, Qifei [Department of Occupational and Environmental Health, State Key Laboratory of Environmental Health (Incubating), School of Public Health, Tongji Medical College, Huazhong University of Science and Technology, Wuhan (China); Zhang, Wangzhen [Institute of Industrial Health, Wuhan Iron & Steel (Group) Corporation, Wuhan 430070, China. (China); Wang, Suhan; He, Meian; Zhang, Xiaomin; Wu, Tangchun [Department of Occupational and Environmental Health, State Key Laboratory of Environmental Health (Incubating), School of Public Health, Tongji Medical College, Huazhong University of Science and Technology, Wuhan (China); Guo, Huan, E-mail: ghuan5011@hust.edu.cn [Department of Occupational and Environmental Health, State Key Laboratory of Environmental Health (Incubating), School of Public Health, Tongji Medical College, Huazhong University of Science and Technology, Wuhan (China)

    2015-07-15

    Heavy metals and polycyclic aromatic hydrocarbons (PAHs) are predominate toxic constituents of particulate air pollution that may be related to the increased risk of cardiopulmonary events. We aim to investigate the effects of the toxic heavy metals (arsenic, As; cadmium, Cd; chromium, Cr; nickel, Ni; and lead, Pb), and their interactions with PAHs on oxidative stress among coke-oven workers. A total of 1333 male workers were recruited in this study. We determined their urinary levels of As, Cd, Cr, Ni, Pb, twelve PAH metabolites, 8-hydroxydeoxyguanosine (8-OHdG), and 8-iso-prostaglandin-F2α (8-iso-PGF2α). Multivariate linear regression models were used to analyze the effects of these metals and their interactions with PAHs on 8-OHdG and 8-iso-PGF2α levels. It was found that only urinary As and Ni showed marginal or significant positive linear dose-dependent effects on 8-OHdG in this study population, especially among smokers (β=0.103, P=0.073 and β=0.110, P=0.002, respectively). After stratifying all participants by the quartiles of ΣOH-PAH, all five metals showed linear association with 8-OHdG in the highest quartile subgroup (Q4) of ΣOH-PAHs. However, these five urinary metals showed significantly consistent linear associations with 8-iso-PGF2α in all subjects and each stratum. Urinary ΣOH-PAHs can significant modify the effects of heavy metals on oxidative stress, while co-exposure to both high levels of ΣOH-PAHs and heavy metals render the workers with highest 8-OHdG and 8-iso-PGF2α (all P{sub interaction}≤0.005). This study showed evidence on the interaction effects of heavy metals and PAHs on increasing the oxidative stress, and these results warrant further investigation in more longitudinal studies. - Highlights: • Heavy metals and PAHs are predominate toxic constituents of particulate matters. • Urinary As and Ni showed linear dose-dependent effects on 8-OHdG and 8-iso-PGF2α. • PAHs significant interact with toxic metal in increasing 8

  9. The effects of heavy metals and their interactions with polycyclic aromatic hydrocarbons on the oxidative stress among coke-oven workers

    International Nuclear Information System (INIS)

    Wang, Tian; Feng, Wei; Kuang, Dan; Deng, Qifei; Zhang, Wangzhen; Wang, Suhan; He, Meian; Zhang, Xiaomin; Wu, Tangchun; Guo, Huan

    2015-01-01

    Heavy metals and polycyclic aromatic hydrocarbons (PAHs) are predominate toxic constituents of particulate air pollution that may be related to the increased risk of cardiopulmonary events. We aim to investigate the effects of the toxic heavy metals (arsenic, As; cadmium, Cd; chromium, Cr; nickel, Ni; and lead, Pb), and their interactions with PAHs on oxidative stress among coke-oven workers. A total of 1333 male workers were recruited in this study. We determined their urinary levels of As, Cd, Cr, Ni, Pb, twelve PAH metabolites, 8-hydroxydeoxyguanosine (8-OHdG), and 8-iso-prostaglandin-F2α (8-iso-PGF2α). Multivariate linear regression models were used to analyze the effects of these metals and their interactions with PAHs on 8-OHdG and 8-iso-PGF2α levels. It was found that only urinary As and Ni showed marginal or significant positive linear dose-dependent effects on 8-OHdG in this study population, especially among smokers (β=0.103, P=0.073 and β=0.110, P=0.002, respectively). After stratifying all participants by the quartiles of ΣOH-PAH, all five metals showed linear association with 8-OHdG in the highest quartile subgroup (Q4) of ΣOH-PAHs. However, these five urinary metals showed significantly consistent linear associations with 8-iso-PGF2α in all subjects and each stratum. Urinary ΣOH-PAHs can significant modify the effects of heavy metals on oxidative stress, while co-exposure to both high levels of ΣOH-PAHs and heavy metals render the workers with highest 8-OHdG and 8-iso-PGF2α (all P interaction ≤0.005). This study showed evidence on the interaction effects of heavy metals and PAHs on increasing the oxidative stress, and these results warrant further investigation in more longitudinal studies. - Highlights: • Heavy metals and PAHs are predominate toxic constituents of particulate matters. • Urinary As and Ni showed linear dose-dependent effects on 8-OHdG and 8-iso-PGF2α. • PAHs significant interact with toxic metal in increasing 8-OHd

  10. Demonstrative study on the production of hydrogen and aromatic compounds originated from biogas in the Dairy area

    International Nuclear Information System (INIS)

    Yukoh Shudo; Takashi Ohkubo; Yoshiaki Hideshima

    2006-01-01

    The biogas yielded by methane fermentation of cow slurry was provided for the experimental facilities and the refined methane was introduced to the methane direct reformer. Dehydrogenation and aromatization of methane generated hydrogen and aromatic compounds, such as benzene. In order to keep the conversion rate, pre-treatment and regeneration of the catalysts were carried out and in order to control coking at the catalysts, hydrogen was added to the material methane. Moreover a part of the un-reacted methane was introduced to the steam reformer and 99.99% pure hydrogen was produced by the pressure swing adsorption (PSA). With the result that, it was supposed that pre-treating by methane and hydrogen, repeating regeneration by hydrogen, and more than 9% hydrogen addition were needed to stabilize the formation of hydrogen and benzene. And furthermore, material balance of the experimental facilities was clarified. (authors)

  11. Electrochemical characterisation of solid oxide cell electrodes for hydrogen production

    DEFF Research Database (Denmark)

    Bernuy-Lopez, Carlos; Knibbe, Ruth; He, Zeming

    2011-01-01

    Oxygen electrodes and steam electrodes are designed and tested to develop improved solid oxide electrolysis cells for H2 production with the cell support on the oxygen electrode. The electrode performance is evaluated by impedance spectroscopy testing of symmetric cells at open circuit voltage (OCV...

  12. Modification of Casein by the Lipid Oxidation Product Malondialdehyde

    NARCIS (Netherlands)

    Adams, A.; Kimpe, de N.; Boekel, van T.

    2008-01-01

    The reaction of malondialdehyde with casein was studied in aqueous solution to evaluate the impact of this lipid oxidation product on food protein modification. By using multiresponse modeling, a kinetic model was developed for this reaction. The influence of temperature and pH on protein browning

  13. Fission product release by fuel oxidation after water ingress

    International Nuclear Information System (INIS)

    Schreiber.

    1990-01-01

    On the basis of data obtained by a literature search, a computer code has been established for the calculation of the degree of oxidation of the fuel in the damaged fuel particles, and hence of the fission product release as a function of the time period of steam ingress. (orig.) [de

  14. Controlling nitrous oxide emissions from grassland livestock production systems

    NARCIS (Netherlands)

    Oenema, O.; Gebauer, G.; Rodriguez, M.; Sapek, A.; Jarvis, S.C.; Corré, W.J.; Yamulki, S.

    1998-01-01

    There is growing awareness that grassland livestock production systems are major sources of nitrous oxide (N2O). Controlling these emissions requires a thorough understanding of all sources and controlling factors at the farm level. This paper examines the various controlling factors and proposes

  15. Bee products prevent agrichemical-induced oxidative damage in fish.

    Directory of Open Access Journals (Sweden)

    Daiane Ferreira

    Full Text Available In southern South America and other parts of the world, aquaculture is an activity that complements agriculture. Small amounts of agrichemicals can reach aquaculture ponds, which results in numerous problems caused by oxidative stress in non-target organisms. Substances that can prevent or reverse agrichemical-induced oxidative damage may be used to combat these effects. This study includes four experiments. In each experiment, 96 mixed-sex, 6-month-old Rhamdia quelen (118±15 g were distributed into eight experimental groups: a control group that was not exposed to contaminated water, three groups that were exposed to various concentrations of bee products, three groups that were exposed to various concentrations of bee products plus tebuconazole (TEB; Folicur 200 CE™ and a group that was exposed to 0.88 mg L(-1 of TEB alone (corresponding to 16.6% of the 96-h LC50. We show that waterborne bee products, including royal jelly (RJ, honey (H, bee pollen (BP and propolis (P, reversed the oxidative damage caused by exposure to TEB. These effects were likely caused by the high polyphenol contents of these bee-derived compounds. The most likely mechanism of action for the protective effects of bee products against tissue oxidation and the resultant damage is that the enzymatic activities of superoxide dismutase (SOD, catalase (CAT and glutathione-S-transferase (GST are increased.

  16. Bee products prevent agrichemical-induced oxidative damage in fish.

    Science.gov (United States)

    Ferreira, Daiane; Rocha, Helio Carlos; Kreutz, Luiz Carlos; Loro, Vania Lucia; Marqueze, Alessandra; Koakoski, Gessi; da Rosa, João Gabriel Santos; Gusso, Darlan; Oliveira, Thiago Acosta; de Abreu, Murilo Sander; Barcellos, Leonardo José Gil

    2013-01-01

    In southern South America and other parts of the world, aquaculture is an activity that complements agriculture. Small amounts of agrichemicals can reach aquaculture ponds, which results in numerous problems caused by oxidative stress in non-target organisms. Substances that can prevent or reverse agrichemical-induced oxidative damage may be used to combat these effects. This study includes four experiments. In each experiment, 96 mixed-sex, 6-month-old Rhamdia quelen (118±15 g) were distributed into eight experimental groups: a control group that was not exposed to contaminated water, three groups that were exposed to various concentrations of bee products, three groups that were exposed to various concentrations of bee products plus tebuconazole (TEB; Folicur 200 CE™) and a group that was exposed to 0.88 mg L(-1) of TEB alone (corresponding to 16.6% of the 96-h LC50). We show that waterborne bee products, including royal jelly (RJ), honey (H), bee pollen (BP) and propolis (P), reversed the oxidative damage caused by exposure to TEB. These effects were likely caused by the high polyphenol contents of these bee-derived compounds. The most likely mechanism of action for the protective effects of bee products against tissue oxidation and the resultant damage is that the enzymatic activities of superoxide dismutase (SOD), catalase (CAT) and glutathione-S-transferase (GST) are increased.

  17. ARIES Oxide Production Program Annual Report - FY14

    Energy Technology Data Exchange (ETDEWEB)

    Kelley, Evelyn A. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Dinehart, Steven Mark [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2015-02-01

    A summary of the major accomplishments (September), milestones, financial summary, project performance and issues facing the ARIES Oxide Production Program at the close of FY14 is presented in this Executive Summary. Annual accomplishments are summarized in the body of the report.

  18. Thiol dioxygenase turnover yields benzothiazole products from 2-mercaptoaniline and O2-dependent oxidation of primary alcohols.

    Science.gov (United States)

    Morrow, William P; Sardar, Sinjinee; Thapa, Pawan; Hossain, Mohammad S; Foss, Frank W; Pierce, Brad S

    2017-10-01

    Thiol dioxygenases are non-heme mononuclear iron enzymes that catalyze the O 2 -dependent oxidation of free thiols (-SH) to produce the corresponding sulfinic acid (-SO 2 - ). Previous chemical rescue studies identified a putative Fe III -O 2 - intermediate that precedes substrate oxidation in Mus musculus cysteine dioxygenase (Mm CDO). Given that a similar reactive intermediate has been identified in the extradiol dioxygenase 2, 3-HCPD, it is conceivable that these enzymes share other mechanistic features with regard to substrate oxidation. To explore this possibility, enzymatic reactions with Mm CDO (as well as the bacterial 3-mercaptopropionic acid dioxygenase, Av MDO) were performed using a substrate analogue (2-mercaptoaniline, 2ma). This aromatic thiol closely approximates the catecholic substrate of homoprotocatechuate of 2, 3-HPCD while maintaining the 2-carbon thiol-amine separation preferred by Mm CDO. Remarkably, both enzymes exhibit 2ma-gated O 2 -consumption; however, none of the expected products for thiol dioxygenase or intra/extradiol dioxygenase reactions were observed. Instead, benzothiazoles are produced by the condensation of 2ma with aldehydes formed by an off-pathway oxidation of primary alcohols added to aqueous reactions to solubilize the substrate. The observed oxidation of 1º-alcohols in 2ma-reactions is consistent with the formation of a high-valent intermediate similar to what has been reported for cytochrome P450 and mononuclear iron model complexes. Copyright © 2017 Elsevier Inc. All rights reserved.

  19. Oxidative stress and respiratory symptoms due to human exposure to polycyclic aromatic hydrocarbons (PAHs) in Kumasi, Ghana

    International Nuclear Information System (INIS)

    Bortey-Sam, Nesta; Ikenaka, Yoshinori; Akoto, Osei; Nakayama, Shouta M.M.; Asante, Kwadwo A.; Baidoo, Elvis; Obirikorang, Christian; Saengtienchai, Aksorn; Isoda, Norikazu; Nimako, Collins

    2017-01-01

    Studies of polycyclic aromatic hydrocarbons (PAHs) and its metabolites in PM10, soils, rat livers and cattle urine in Kumasi, Ghana, revealed high concentrations and cancer potency. In addition, WHO and IARC have reported an increase in cancer incidence and respiratory diseases in Ghana. Human urine were therefore collected from urban and control sites to: assess the health effects associated with PAHs exposure using malondialdehyde (MDA) and 8-hydroxy-2-deoxyguanosine (8-OHdG); identify any association between OH-PAHs, MDA, 8-OHdG with age and sex; and determine the relationship between PAHs exposure and occurrence of respiratory diseases. From the results, urinary concentrations of the sum of OH-PAHs (∑OHPAHs) were significantly higher from urban sites compared to the control site. Geometric mean concentrations adjusted by specific gravity, GM SG , indicated 2-OHNaphthalene (2-OHNap) (6.01 ± 4.21 ng/mL) as the most abundant OH-PAH, and exposure could be through the use of naphthalene-containing-mothballs in drinking water purification, insect repellent, freshener in clothes and/or “treatment of various ailments”. The study revealed that exposure to naphthalene significantly increases the occurrence of persistent cough (OR = 2.68, CI: 1.43–5.05), persistent headache (OR = 1.82, CI: 1.02–3.26), tachycardia (OR = 3.36, CI: 1.39–8.10) and dyspnea (OR = 3.07, CI: 1.27–7.43) in Kumasi residents. Highest level of urinary 2-OHNap (224 ng/mL) was detected in a female, who reported symptoms of persistent cough, headache, tachycardia, nasal congestion and inflammation, all of which are symptoms of naphthalene exposure according to USEPA. The ∑OHPAHs, 2-OHNap, 2-3-OHFluorenes, and -OHPhenanthrenes showed a significantly positive correlation with MDA and 4-OHPhenanthrene with 8-OHdG, indicating possible lipid peroxidation/cell damage or degenerative disease in some participants. MDA and 8-OHdG were highest in age group 21–60. The present study

  20. Catalytic synthesis of aromatic diisocyanates by means of carbonylation of nitrocompounds with carbon monoxide

    Energy Technology Data Exchange (ETDEWEB)

    Nefedov, B K; Manov-Yuvenskii, V I; Khoshdurdev, Kh O; Novikov, S S [AN SSSR, Moscow. Inst. Organicheskoj Khimii

    1977-02-11

    The development of an active and selective heterogeneous catalyst for synthesis of aromatic diisocyanates has been studied. The catalytic ability of the catalyst PdO-MoO/sub 3/-Fe/sub 2/O/sub 3/ deposited on ..gamma..-Al/sub 2/O/sub 3/ has been investigated in the reactions of carbonylation of aromatic dinitrocompounds with carbon oxide. The effect of the catalyst composition, method of catalyst production, reaction temperature and pressure on the catalytic ability have been studied. It has been established that the catalyst PdO-MoO/sub 3/-Fe/sub 2/O/sub 3/(2-6:1:1) deposited on ..gamma..-Al/sub 2/O/sub 3/ is highly active and selective in the reactions of carbonilation of aromatic dinitrocompounds at 210 deg and 300 atm. It has been used for synthesis of aromatic diisocyanates in yield 32-75%.

  1. Polycyclic aromatic hydrocarbons residues in Gentile di maiale, a smoked meat product typical of some mountain areas in Latina province (Central Italy

    Directory of Open Access Journals (Sweden)

    Giuseppe Carrabs

    2014-05-01

    Full Text Available Gentile di maiale is a typical meat product prepared in some traditional plants of Latina Province (Central Italy. It is obtained from dehydration, salting, smoking and ripening of swine rectum. Aim of this study was to evaluate the influence of the traditional smoking process on polycyclic aromatic hydrocarbons (PAHs content by means of high-performance liquid chromatographic/fluorescence detection. Polycyclic aromatic hydrocarbons detected in 8 samples of raw material (swine rectum and samples of smoked gentile were: benzo[a]anthracene, chrisene, benzo[b]fluoranthene, benzo[k]fluoranthene, benzo[a] pyrene, benzo[a,h]anthracene. Their residues were detected in all samples of finished product. European Regulation 835/2011 established two levels of PAHs content in meat products. According to first levels, in force until September 2014, only 2 out of 8 samples exceeded legal limit. According to the subsequent, more restrictive, limits all samples would be non-compliant. An improvement and a standardisation of traditional smoking procedures are recommended.

  2. Bilirubin and its oxidation products damage brain white matter

    Science.gov (United States)

    Lakovic, Katarina; Ai, Jinglu; D'Abbondanza, Josephine; Tariq, Asma; Sabri, Mohammed; Alarfaj, Abdullah K; Vasdev, Punarjot; Macdonald, Robert Loch

    2014-01-01

    Brain injury after intracerebral hemorrhage (ICH) occurs in cortex and white matter and may be mediated by blood breakdown products, including hemoglobin and heme. Effects of blood breakdown products, bilirubin and bilirubin oxidation products, have not been widely investigated in adult brain. Here, we first determined the effect of bilirubin and its oxidation products on the structure and function of white matter in vitro using brain slices. Subsequently, we determined whether these compounds have an effect on the structure and function of white matter in vivo. In all, 0.5 mmol/L bilirubin treatment significantly damaged both the function and the structure of myelinated axons but not the unmyelinated axons in brain slices. Toxicity of bilirubin in vitro was prevented by dimethyl sulfoxide. Bilirubin oxidation products (BOXes) may be responsible for the toxicity of bilirubin. In in vivo experiments, unmyelinated axons were found more susceptible to damage from bilirubin injection. These results suggest that unmyelinated axons may have a major role in white-matter damage in vivo. Since bilirubin and BOXes appear in a delayed manner after ICH, preventing their toxic effects may be worth investigating therapeutically. Dimethyl sulfoxide or its structurally related derivatives may have a potential therapeutic value at antagonizing axonal damage after hemorrhagic stroke. PMID:25160671

  3. Corrosion-product transport, oxidation state and remedial measures

    International Nuclear Information System (INIS)

    Sawicki, J.A.; Brett, M.E.; Tapping, R.L.

    1998-10-01

    The issues associated with monitoring and controlling corrosion-product transport (CPT) in the balance-of-plant (BOP) and steam generators (SG) of CANDU stations are briefly reviewed. Efforts are focused on minimizing corrosion of carbon steel, which is used extensively in the CANDU primary and secondary systems. Emphasis is placed on the corrosion-product oxidation state as a monitor of water chemistry effectiveness and as a monitor of system corrosion effects. The discussion is based mostly on the results of observations from Ontario Hydro plants, and their comparisons with pressurized-water reactors. The effects of low oxygen and elevated hydrazine chemistry are reviewed, as well as the effects of layup and various startup conditions. Progress in monitoring electrochemical potential (ECP) at Ontario Hydro plants and its relationship to the oxidation state of corrosion products is reviewed. Observations on CPT on the primary side of SGs are also discussed. (author)

  4. Black tattoo inks induce reactive oxygen species production correlating with aggregation of pigment nanoparticles and product brand but not with the polycyclic aromatic hydrocarbon content.

    Science.gov (United States)

    Høgsberg, Trine; Jacobsen, Nicklas Raun; Clausen, Per Axel; Serup, Jørgen

    2013-07-01

    Black tattoo inks are composed of carbon nanoparticles, additives and water and may contain polycyclic aromatic hydrocarbons (PAHs). We aimed to clarify whether reactive oxygen species (ROS) induced by black inks in vitro is related to pigment chemistry, physico-chemical properties of the ink particles and the content of chemical additives and contaminants including PAHs. The study included nine brands of tattoo inks of six colours each (black, red, yellow, blue, green and white) and two additional black inks of different brands (n = 56). The ROS formation potential was determined by the dichlorofluorescein (DCFH) assay. A semiquantitative method was developed for screening extractable organic compounds in tattoo ink based on gas chromatography-mass spectrometry (GC-MS) and matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF-MS). Two black inks produced high amounts of ROS. Peroxyl radicals accounted for up to 72% of the free radicals generated, whereas hydroxyl radicals and H₂O₂ accounted for inks aggregated strongly in water in contrast to the other black inks. They did not exhibit any shared pattern in PAHs and other organic substances. Aggregation was exclusively shared by all ink colours belonging to the same two brands. Ten of 11 black inks had PAH concentrations exceeding the European Council's recommended level, and all 11 exceeded the recommended level for benzo(a)pyrene. It is a new finding that aggregation of tattoo pigment particles correlates with ROS production and brand, independently of chemical composition including PAHs. ROS is hypothesized to be implicated in minor clinical symptoms. © 2013 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

  5. Supported manganese oxide on TiO{sub 2} for total oxidation of toluene and polycyclic aromatic hydrocarbons (PAHs): Characterization and catalytic activity

    Energy Technology Data Exchange (ETDEWEB)

    Aboukaïs, Antoine, E-mail: aboukais@univ-littoral.fr [Univ Lille Nord de France, 59000 Lille (France); Equipe Catalyse, UCEIV, EA 4492, MREI, ULCO, 59140 Dunkerque (France); Abi-Aad, Edmond [Univ Lille Nord de France, 59000 Lille (France); Equipe Catalyse, UCEIV, EA 4492, MREI, ULCO, 59140 Dunkerque (France); Taouk, Bechara [Laboratoire de Sécurité des procédés Chimiques (LSPC), EA 4704, INSA Rouen, Avenue de l' Université, 76801 Saint Etienne du Rouvray (France)

    2013-11-01

    Manganese oxide catalysts supported on titania (TiO{sub 2}) were prepared by incipient wetness impregnation method in order to elaborate catalysts for total oxidation of toluene and PAHs. These catalysts have been characterized by means of X-ray diffraction (XRD), electron paramagnetic resonance (EPR), temperature programmed reduction (TPR) and temperature programmed desorption (TPD). It has been shown that for the 5%Mn/TiO{sub 2} catalyst the reducibility and the mobility of oxygen are higher compared, in one side, to other x%Mn/TiO{sub 2} samples and, in another side, to catalysts where TiO{sub 2} support was replaced by γ-Al{sub 2}O{sub 3} or SiO{sub 2}. It has been shown that the content of manganese loading on TiO{sub 2} has an effect on the catalytic activity in the toluene oxidation. A maximum of activity was obtained for the 5%Mn/TiO{sub 2} catalyst where the total conversion of toluene was reached at 340 °C. This activity seems to be correlated to the presence of the Mn{sup 3+}/Mn{sup 4+} redox couple in the catalyst. When the Mn content increases, large particles of Mn{sub 2}O{sub 3} appear leading then to the decrease in the corresponding activity. In addition, compared to both other supports, TiO{sub 2} seems to be the best to give the best catalytic activity for the oxidation of toluene when it is loaded with 5% of manganese. For this reason, the latter catalyst was tested for the abatement of some PAHs. The light off temperature of PAHs compounds increases with increasing of benzene rings number and with decreasing of H/C ratio. All of PAHs are almost completely oxidized and converted at temperatures lower than 500 °C. - Highlights: • Preparation of x%MnO{sub 2}/TiO{sub 2} catalysts. • Catalytic oxidation tests of toluene and PAHs. • EPR, TPR and TPD characterizations of Mn(II) and Mn(IV) ions.

  6. Global simulation of aromatic volatile organic compounds in the atmosphere

    Science.gov (United States)

    Cabrera Perez, David; Taraborrelli, Domenico; Pozzer, Andrea

    2015-04-01

    Among the large number of chemical compounds in the atmosphere, the organic group plays a key role in the tropospheric chemistry. Specifically the subgroup called aromatics is of great interest. Aromatics are the predominant trace gases in urban areas due to high emissions, primarily by vehicle exhausts and fuel evaporation. They are also present in areas where biofuel is used (i.e residential wood burning). Emissions of aromatic compounds are a substantial fraction of the total emissions of the volatile organic compounds (VOC). Impact of aromatics on human health is very important, as they do not only contribute to the ozone formation in the urban environment, but they are also highly toxic themselves, especially in the case of benzene which is able to trigger a range of illness under long exposure, and of nitro-phenols which cause detrimental for humans and vegetation even at very low concentrations. The aim of this work is to assess the atmospheric impacts of aromatic compounds on the global scale. The main goals are: lifetime and budget estimation, mixing ratios distribution, net effect on ozone production and OH loss for the most emitted aromatic compounds (benzene, toluene, xylenes, ethylbenzene, styrene and trimethylbenzenes). For this purpose, we use the numerical chemistry and climate simulation ECHAM/MESSy Atmospheric Chemistry (EMAC) model to build the global atmospheric budget for the most emitted and predominant aromatic compounds in the atmosphere. A set of emissions was prepared in order to include biomass burning, vegetation and anthropogenic sources of aromatics into the model. A chemical mechanism based on the Master Chemical Mechanism (MCM) was developed to describe the chemical oxidation in the gas phase of these aromatic compounds. MCM have been reduced in terms of number of chemical equation and species in order to make it affordable in a 3D model. Additionally other features have been added, for instance the production of HONO via ortho

  7. Kinetics of abiotic nitrous oxide production via oxidation of hydroxylamine by particulate metals in seawater

    Science.gov (United States)

    Cavazos, A. R.; Taillefert, M.; Glass, J. B.

    2016-12-01

    The oceans are a significant of nitrous oxide (N2O) to the atmosphere. Current models of global oceanic N2­O flux focus on microbial N2O cycling and often ignore abiotic reactions, such as the thermodynamically favorable oxidation of the nitrification intermediate hydroxylamine (NH2OH) by Mn(IV) or Fe(III). At circumneutral pH, NH2OH oxidation is more thermodynamically favorable via Mn(IV) than Fe(III) reduction. We characterized the kinetics of NH2OH oxidation in synthetic ocean water at pH 5.1-8.8 using microsensor electrodes to measure real-time N2O production. N2O production rates and yield were greater when NH2OH was oxidized by Mn(IV) than Fe(III). Accordingly, the reduction of Mn(IV) was first order with respect to NH2OH whereas the reduction of Fe(III) was zero order with respect to NH2OH. Interestingly, the order of the reaction with respect to Mn(IV) appears to be negative whereas the reaction is second order with respect to Fe(III). The inverse order with respect to Mn(IV) may be due to the aggregation of particles in seawater, which decreases their surface area and changes their reactivity. Finally, the reaction is first order with respect to protons with Fe(III) as the oxidant but zero order with Mn(IV). The stronger effect of the pH on the reaction with Fe(III) as the oxidant compared to Mn(IV) reflects the stoichiometry of these two reactions, as each mole of N2O produced by Fe(III) reduction consumes eight protons while each mole of N2O produced with Mn(IV) as the oxidant requires only four protons. Our data show that abiotic NH2OH oxidation by Mn(IV) or Fe(III) particles may represent a significant source of N2O in seawater. These findings suggest that abiotic N2O production in marine waters may be significant in areas of the oceans where particulate metals originating from aerosols, dust, or rivers may react with NH2OH released from ammonia-oxidizing microorganisms.

  8. Chemical Characterization and Reactivity of Fuel-Oxidizer Reaction Product

    Science.gov (United States)

    David, Dennis D.; Dee, Louis A.; Beeson, Harold D.

    1997-01-01

    Fuel-oxidizer reaction product (FORP), the product of incomplete reaction of monomethylhydrazine and nitrogen tetroxide propellants prepared under laboratory conditions and from firings of Shuttle Reaction Control System thrusters, has been characterized by chemical and thermal analysis. The composition of FORP is variable but falls within a limited range of compositions that depend on three factors: the fuel-oxidizer ratio at the time of formation; whether the composition of the post-formation atmosphere is reducing or oxidizing; and the reaction or post-reaction temperature. A typical composition contains methylhydrazinium nitrate, ammonium nitrate, methylammonium nitrate, and trace amounts of hydrazinium nitrate and 1,1-dimethylhydrazinium nitrate. Thermal decomposition reactions of the FORP compositions used in this study were unremarkable. Neither the various compositions of FORP, the pure major components of FORP, nor mixtures of FORP with propellant system corrosion products showed any unusual thermal activity when decomposed under laboratory conditions. Off-limit thruster operations were simulated by rapid mixing of liquid monomethylhydrazine and liquid nitrogen tetroxide in a confined space. These tests demonstrated that monomethylhydrazine, methylhydrazinium nitrate, ammonium nitrate, or Inconel corrosion products can induce a mixture of monomethylhydrazine and nitrogen tetroxide to produce component-damaging energies. Damaging events required FORP or metal salts to be present at the initial mixing of monomethylhydrazine and nitrogen tetroxide.

  9. Chemical oxidation of unsymmetrical dimethylhydrazine transformation products in water

    Directory of Open Access Journals (Sweden)

    Madi Abilev

    2015-03-01

    Full Text Available Oxidation of unsymmetrical dimethylhydrazine (UDMH during a water treatment has several disadvantages including formation of stable toxic byproducts. Effectiveness of treatment methods in relation to UDMH transformation products is currently poorly studied. This work considers the effectiveness of chemical oxidants in respect to main metabolites of UDMH – 1-formyl-2,2-dimethylhydrazine, dimethylaminoacetontrile, N-nitrosodimethylamine and 1-methyl-1H-1,2,4-triazole. Experiments on chemical oxidation by Fenton's reagent, potassium permanganate and sodium nitrite were conducted. Quantitative determination was performed by HPLC. Oxidation products were identified by gas chromatography-mass spectrometry in combination with solid-phase microextraction. 1-Formyl-2,2-dimethylhydrazine was completely oxidized by Fenton's reagent with formation of formaldehyde N-formyl-N-methyl-hydrazone, 1,4-dihydro-1,4-dimethyl-5H-tetrazol-5-one by the action of potassium permanganate and N-methyl-N-nitro-methanamine in the presence of sodium nitrite. Oxidation of 1-formyl-2,2-dimethylhydrazine also resulted in formation of N-nitrosodimethylamine. Oxidation of dimethylaminoacetontrile proceeded with formation of hydroxyacetonitrile, dimethylformamide and 1,2,5-trimethylpyrrole. After 30 days, dimethylaminoacetontrile was not detected in the presence of Fenton’s reagent and potassium permanganate, but it’s concentration in samples with sodium nitrite was 77.3 mg/L. In the presence of Fenton’s reagent, potassium permanganate and sodium nitrite after 30 days, N-nitrosodimethylamine concentration decreased by 85, 80 and 50%, respectively. In control sample, N-nitrosodimethylamine concentration decreased by 50%, indicating that sodium nitrite has no effect of on N-nitrosodimethylamine concentration. Only Fenton's reagent allowed to reduce the concentration of 1-methyl-1H-1,2,4-triazole to 50% in 30 days. In the presence of other oxidants, 1-methyl-1H-1,2,4-triazole

  10. Production of Oxygen from Lunar Regolith by Molten Oxide Electrolysis

    Science.gov (United States)

    Curreri, Peter A.

    2009-01-01

    This paper describes the use of the molten oxide electrolysis (MOE) process for the extraction of oxygen for life support and propellant, and silicon and metallic elements for use in fabrication on the Moon. The Moon is rich in mineral resources, but it is almost devoid of chemical reducing agents, therefore, molten oxide electrolysis is ideal for extraction, since the electron is the only practical reducing agent. MOE has several advantages over other extraction methods. First, electrolytic processing offers uncommon versatility in its insensitivity to feedstock composition. Secondly, oxide melts boast the twin key attributes of highest solubilizing capacity for regolith and lowest volatility of any candidate electrolytes. The former is critical in ensuring high productivity since cell current is limited by reactant solubility, while the latter simplifies cell design by obviating the need for a gas-tight reactor to contain evaporation losses as would be the case with a gas or liquid phase fluoride reagent operating at such high temperatures. Alternatively, MOE requires no import of consumable reagents (e.g. fluorine and carbon) as other processes do, and does not rely on interfacing multiple processes to obtain refined products. Electrolytic processing has the advantage of selectivity of reaction in the presence of a multi-component feed. Products from lunar regolith can be extracted in sequence according to the stabilities of their oxides as expressed by the values of the free energy of oxide formation (e.g. chromium, manganese, Fe, Si, Ti, Al, magnesium, and calcium). Previous work has demonstrated the viability of producing Fe and oxygen from oxide mixtures similar in composition to lunar regolith by molten oxide electrolysis (electrowinning), also called magma electrolysis having shown electrolytic extraction of Si from regolith simulant. This paper describes recent advances in demonstrating the MOE process by a joint project with participation by NASA KSC and

  11. Two-Step Electrochemical Intercalation and Oxidation of Graphite for the Mass Production of Graphene Oxide.

    Science.gov (United States)

    Cao, Jianyun; He, Pei; Mohammed, Mahdi A; Zhao, Xin; Young, Robert J; Derby, Brian; Kinloch, Ian A; Dryfe, Robert A W

    2017-12-06

    Conventional chemical oxidation routes for the production of graphene oxide (GO), such as the Hummers' method, suffer from environmental and safety issues due to their use of hazardous and explosive chemicals. These issues are addressed by electrochemical oxidation methods, but such approaches typically have a low yield due to inhomogeneous oxidation. Herein we report a two-step electrochemical intercalation and oxidation approach to produce GO on the large laboratory scale (tens of grams) comprising (1) forming a stage 1 graphite intercalation compound (GIC) in concentrated sulfuric acid and (2) oxidizing and exfoliating the stage 1 GIC in an aqueous solution of 0.1 M ammonium sulfate. This two-step approach leads to GO with a high yield (>70 wt %), good quality (>90%, monolayer), and reasonable oxygen content (17.7 at. %). Moreover, the as-produced GO can be subsequently deeply reduced (3.2 at. % oxygen; C/O ratio 30.2) to yield highly conductive (54 600 S m -1 ) reduced GO. Electrochemical capacitors based on the reduced GO showed an ultrahigh rate capability of up to 10 V s -1 due to this high conductivity.

  12. Oxidative stress induced inflammation initiates functional decline of tear production.

    Directory of Open Access Journals (Sweden)

    Yuichi Uchino

    Full Text Available Oxidative damage and inflammation are proposed to be involved in an age-related functional decline of exocrine glands. However, the molecular mechanism of how oxidative stress affects the secretory function of exocrine glands is unclear. We developed a novel mev-1 conditional transgenic mouse model (Tet-mev-1 using a modified tetracycline system (Tet-On/Off system. This mouse model demonstrated decreased tear production with morphological changes including leukocytic infiltration and fibrosis. We found that the mev-1 gene encodes Cyt-1, which is the cytochrome b(560 large subunit of succinate-ubiquinone oxidoreductase in complex II of mitochondria (homologous to succinate dehydrogenase C subunit (SDHC in humans. The mev-1 gene induced excessive oxidative stress associated with ocular surface epithelial damage and a decrease in protein and aqueous secretory function. This new model provides evidence that mitochondrial oxidative damage in the lacrimal gland induces lacrimal dysfunction resulting in dry eye disease. Tear volume in Tet-mev-1 mice was lower than in wild type mice and histopathological analyses showed the hallmarks of lacrimal gland inflammation by intense mononuclear leukocytic infiltration and fibrosis in the lacrimal gland of Tet-mev-1 mice. These findings strongly suggest that oxidative stress can be a causative factor for the development of dry eye disease.

  13. Characteristics of oxidative homolytic alkylation of imidazoles and organic-inorganic hybrid extended networks from large aromatic building blocks

    Science.gov (United States)

    Li, Kunhao

    The discovery of the dramatic in vitro antimalarial activity of 2-iodo-L-histidine and 2-fluoro-L-histidine, as well as their in vivo limitations, has prompted a systematic search for novel 2-substituted imidazoles and bioimidazoles as agents against human malaria. Previous research has shown that the regioselective alkyl free radical substitution on imidazoles and bioimidazoles could serve as a simple and efficient route to a wide variety of 2-alkylimidazoles. In this research, this methodology was successfully extended to include alkyl radicals substituted with various functional groups such as amide or ester. While this novel methodology should be of some synthetic utility when tertiary radicals are used, poorer yields are usually encountered in the cases of primary radicals. In the second part of this dissertation, a series of novel ligands containing multiple ortho-bis(organothio) groups were synthesized and their coordination and network forming properties were studied in the context of crystalline organic-inorganic hybrid extended networks. For the syntheses of HRTTs [2,3,6,7,10,11-hexakis(alkylthio)triphenylenes], a simpler, safer and higher yielding one-pot process was developed. Quenching the hexa-anions (formed when sodium methylthiolate was refluxed with hexabromotriphenylene) with alkyl halides or acid chlorides afforded HRTTs. This newly developed process was also successfully expanded to the pyrene system. In the syntheses of unsymmetrically substituted triphenlyenes, it was shown for the first time that the oxidative cyclization process is applicable to thioether containing systems, pointing to a novel strategy for the preparation of this type of unsymmetrically substituted triphenlyenes. Treating these novel ligands with various metal salts [i.e. bismuth(III) chloride and bismuth(III) bromide] under carefully controlled conditions resulted in a series of air-stable semiconductive coordination networks. Their single crystal structures were

  14. Oxidation of the odorous compound 2,4,6-trichloroanisole by UV activated persulfate: Kinetics, products, and pathways.

    Science.gov (United States)

    Luo, Congwei; Jiang, Jin; Ma, Jun; Pang, Suyan; Liu, Yongze; Song, Yang; Guan, Chaoting; Li, Juan; Jin, Yixin; Wu, Daoji

    2016-06-01

    The transformation efficiency and products of an odorous compound 2,4,6-trichloroanisole (TCA) at the wavelength of 254 nm in the presence of persulfate were investigated for the first time. The effects of water matrix (i.e., natural organic matter (NOM), pH, carbonate/bicarbonate (HCO3(-)/CO3(2-)), and chloride ions (Cl(-))) were evaluated. The second order rate constant of TCA reacting with sulfate radical (SO4(-)) was determined to be (3.72 ± 0.10) × 10(9) M(-1) s(-1). Increasing dosage of persulfate increased the observed pseudo-first-order rate constant for TCA degradation (kobs), and the contribution of SO4(-) to TCA degradation was much higher than that of HO at each experimental condition. Degradation rate of TCA decreased with pH increasing from 4.0 to 9.0, which could be explained by the lower radical scavenging effect of dihydrogen phosphate than hydrogen phosphate in acidic condition (pH kinetic results could be described by a steady-state kinetic model. Furthermore, liquid chromatography/electrospray ionization-triple quadrupole mass spectrometry at powerful precursor ion scan approach was used to selectively detect oxidation products of TCA. It was found that 2,4,6-trichorophenol (TCP) was the major oxidation product (i.e., the initial yield of TCP was above 90%). The second order rate constant between TCP and SO4(-) was estimated to be (4.16 ± 0.20) × 10(9) M(-1) s(-1). In addition, three products (i.e., 2,6-dichloro-1,4-benzoquinone and two aromatic ring-opening products) were detected in the reaction of TCP with SO4(-), which also appeared in the oxidation of TCA in the UV/persulfate process. A tentative pathway was proposed, where the initial one-electron oxidation of TCA by SO4(-) and further reactions (e.g., ipso-hydroxylation and aromatic ring-cleavage) of the formed cation intermediate TCA were involved. Copyright © 2016. Published by Elsevier Ltd.

  15. Three-dimensional ionic liquid functionalized magnetic graphene oxide nanocomposite for the magnetic dispersive solid phase extraction of 16 polycyclic aromatic hydrocarbons in vegetable oils.

    Science.gov (United States)

    Zhang, Yun; Zhou, Hua; Zhang, Zhe-Hua; Wu, Xiang-Lun; Chen, Wei-Guo; Zhu, Yan; Fang, Chun-Fu; Zhao, Yong-Gang

    2017-03-17

    In this paper, a novel three-dimensional ionic liquid functionalized magnetic graphene oxide nanocomposite (3D-IL@mGO) was prepared, and used as an effective adsorbent for the magnetic dispersive solid phase extraction (MSPE) of 16 polycyclic aromatic hydrocarbons (PAHs) in vegetable oil prior to gas chromatography-mass spectrometry (GC-MS). The properties of 3D-IL@mGO were characterized by scanning electron micrographs (SEM), X-ray photoelectron spectroscopy (XPS), vibrating sample magnetometer (VSM). The 3D-IL@mGO, functionalized by ionic liquid, exhibited high adsorption toward PAHs. Compared to molecularly imprinted solid phase extraction (MISPE), the MSPE method based on 3D-IL@mGO had less solvent consumption and low cost, and was more efficent to light PAHs in quantitative analysis. Furthermore, the rapid and accurate GC-MS method coupled with 3D-IL@mGO MSPE procedure was successfully applied for the analysis of 16 PAHs in eleven vegetable oil samples from supermarket in Zhejiang Province. The results showed that the concentrations of BaP in 3 out of 11 samples were higher than the legal limit (2.0μg/kg, Commission Regulation 835/2011a), the sum of 8 heavy PAHs (BaA, CHR, BbF, BkF, BaP, IcP, DaA, BgP) in 11 samples was between 3.03μg/kg and 229.5μg/kg. Validation results on linearity, specificity, accuracy, precision and stability, as well as on application to the analysis of PAHs in oil samples demonstrated the applicability to food safety risk monitoring in China. Copyright © 2017 Elsevier B.V. All rights reserved.

  16. L-cysteine-capped core/shell/shell quantum dot-graphene oxide nanocomposite fluorescence probe for polycyclic aromatic hydrocarbon detection.

    Science.gov (United States)

    Adegoke, Oluwasesan; Forbes, Patricia B C

    2016-01-01

    Environmental pollutants, such as the polycyclic aromatic hydrocarbons (PAHs), become widely distributed in the environment after emission from a range of sources, and they have potential biological effects, including toxicity and carcinogenity. In this work, we have demonstrated the analytical potential of a covalently linked L-cysteine-capped CdSeTe/ZnSe/ZnS core/shell/shell quantum dot (QD)-graphene oxide (GO) nanocomposite fluorescence probe to detect PAH compounds in aqueous solution. Water-soluble L-cysteine-capped CdSeTe/ZnSe/ZnS QDs were synthesized for the first time and were covalently bonded to GO. The fluorescence of the QD-GO nanocomposite was enhanced relative to the unconjugated QDs. Various techniques including TEM, SEM, HRSEM, XRD, Raman, FT-IR, UV/vis and fluorescence spectrophotometry were employed to characterize both the QDs and the QD-GO nanocomposite. Four commonly found priority PAH analytes namely; phenanthrene (Phe), anthracene (Ant), pyrene (Py) and naphthalene (Naph), were tested and it was found that each of the PAH analytes enhanced the fluorescence of the QD-GO probe. Phe was selected for further studies as the PL enhancement was significantly greater for this PAH. A limit of detection (LOD) of 0.19 µg/L was obtained for Phe under optimum conditions, whilst the LOD of Ant, Py and Naph were estimated to be ~0.26 µg/L. The fluorescence detection mechanism is proposed. Copyright © 2015 Elsevier B.V. All rights reserved.

  17. Regiospecifically Fluorinated Polycyclic Aromatic Hydrocarbons via Julia-Kocienski Olefination and Oxidative Photocyclization. Effect of Fluorine Atom Substitution on Molecular Shape.

    Science.gov (United States)

    Banerjee, Shaibal; Sinha, Saikat; Pradhan, Padmanava; Caruso, Alessio; Liebowitz, Daniel; Parrish, Damon; Rossi, Miriam; Zajc, Barbara

    2016-05-20

    A modular synthesis of regiospecifically fluorinated polycyclic aromatic hydrocarbons (PAHs) is described. 1,2-Diarylfluoroalkenes, synthesized via Julia-Kocienski olefination (70-99% yields), were converted to isomeric 5- and 6-fluorobenzo[c]phenanthrene, 5-and 6-fluorochrysene, and 9- and 10-benzo[g]chrysene (66-83% yields) by oxidative photocyclization. Photocyclization to 6-fluorochrysene proceeded more slowly than conversion of 1-styrylnaphthalene to chrysene. Higher fluoroalkene dilution led to a more rapid cyclization. Therefore, photocyclizations were performed at higher dilutions. To evaluate the effect of fluorine atom on molecular shapes, X-ray data for 5- and 6-fluorobenzo[c]phenanthrene, 6-fluorochrysene, 9- and 10-fluorobenzo[g]chrysene, and unfluorinated chrysene as well as benzo[g]chrysene were obtained and compared. The fluorine atom caused a small deviation from planarity in the chrysene series and decreased nonplanarity in the benzo[c]phenanthrene derivatives, but its influence was most pronounced in the benzo[g]chrysene series. A remarkable flattening of the molecule was observed in 9-fluorobenzo[g]chrysene, where the short 2.055 Å interatomic distance between bay-region F-9 and H-8, downfield shift of H-8, and a 26.1 Hz coupling between F-9 and C-8 indicate a possible F-9···H-8 hydrogen bond. In addition, in 9-fluorobenzo[g]chrysene, the stacking distance is short at 3.365 Å and there is an additional interaction between the C-11-H and C-10a of a nearby molecule that is almost perpendicular.

  18. 1 - Aromatization of n-hexane and natural gasoline over ZSM-5 zeolite, 2- Wet catalytic oxidation of phenol on fixed bed of active carbon; 1 - Aromatisation de n-hexane et d'essence sur zeolithe ZSM-5, 2 - Oxydation catalytique en voie humide du phenol sur charbon actif

    Energy Technology Data Exchange (ETDEWEB)

    Suwanprasop, S.

    2005-04-15

    I - The production of aromatic hydrocarbons from n-hexane and natural gasoline over Pd loaded ZSM-5 zeolite in a tubular reactor was achieved under the suitable conditions at 400 deg. C, and 0.4 ml/min reactant feeding rate, employing ZSM-5 (0.5% Pd content) as a catalyst. Under these conditions, n-hexane and natural gasoline conversions were found to be 99.7% and 94.3%, respectively (with respective aromatic selectivity of 92.3% and 92.6%). II - Wet catalytic air oxidation of phenol over a commercial active carbon was studied in a three phase fixed bed reactor under mild temperature and oxygen partial pressure. Exit phenol concentration, COD, and intermediates were analysed. Oxidation of phenol was significantly improved when increasing operating temperature, oxygen partial pressure, and liquid space time, while up or down flow modes had only marginal effect. A complete model involving intrinsic kinetics and all mass transfer limitations gave convenient reactor simulation. (author)

  19. Dispersion strengthening of aluminium-aluminium-oxide products

    DEFF Research Database (Denmark)

    Hansen, Niels

    1970-01-01

    The true stress-true strain curves at room temperature and at 400°C were determined for various types of aluminium-aluminium-oxide products containing from 0.2 to 4.7 weight per cent of aluminium oxide. The effect of particles on the initial flow stress and the flow stress for 0.2% offset at room...... temperature and at 400°C is in agreement with Orowan's theory. The increase in flow stress at room temperature for strain values below 3 per cent was related to the plastic strain by the equation σ-σoy=k1ε 1/2, where σoy is the initial flow stress and where k1 increases for increasing volume fraction...... and decreasing particle size of the dispersed particles. A general expression for k1 was derived for the relationship between the dislocation density and the strain in dispersion-strengthened products...

  20. Production and consumption of nitric oxide by three methanotrophic bacteria.

    Science.gov (United States)

    Ren, T; Roy, R; Knowles, R

    2000-09-01

    We studied nitrogen oxide production and consumption by methanotrophs Methylobacter luteus (group I), Methylosinus trichosporium OB3b (group II), and an isolate from a hardwood swamp soil, here identified by 16S ribosomal DNA sequencing as Methylobacter sp. strain T20 (group I). All could consume nitric oxide (nitrogen monoxide, NO), and produce small amounts of nitrous oxide (N(2)O). Only Methylobacter strain T20 produced large amounts of NO (>250 parts per million by volume [ppmv] in the headspace) at specific activities of up to 2.0 x 10(-17) mol of NO cell(-1) day(-1), mostly after a culture became O(2) limited. Production of NO by strain T20 occurred mostly in nitrate-containing medium under anaerobic or nearly anaerobic conditions, was inhibited by chlorate, tungstate, and O(2), and required CH(4). Denitrification (methanol-supported N(2)O production from nitrate in the presence of acetylene) could not be detected and thus did not appear to be involved in the production of NO. Furthermore, cd(1) and Cu nitrite reductases, NO reductase, and N(2)O reductase could not be detected by PCR amplification of the nirS, nirK, norB, and nosZ genes, respectively. M. luteus and M. trichosporium produced some NO in ammonium-containing medium under aerobic conditions, likely as a result of methanotrophic nitrification and chemical decomposition of nitrite. For Methylobacter strain T20, arginine did not stimulate NO production under aerobiosis, suggesting that NO synthase was not involved. We conclude that strain T20 causes assimilatory reduction of nitrate to nitrite, which then decomposes chemically to NO. The production of NO by methanotrophs such as Methylobacter strain T20 could be of ecological significance in habitats near aerobic-anaerobic interfaces where fluctuating O(2) and nitrate availability occur.

  1. Size characterization of metal oxide nanoparticles in commercial sunscreen products

    Science.gov (United States)

    Bairi, Venu Gopal; Lim, Jin-Hee; Fong, Andrew; Linder, Sean W.

    2017-07-01

    There is an increase in the usage of engineered metal oxide (TiO2 and ZnO) nanoparticles in commercial sunscreens due to their pleasing esthetics and greater sun protection efficiency. A number of studies have been done concerning the safety of nanoparticles in sunscreen products. In order to do the safety assessment, it is pertinent to develop novel analytical techniques to analyze these nanoparticles in commercial sunscreens. This study is focused on developing analytical techniques that can efficiently determine particle size of metal oxides present in the commercial sunscreens. To isolate the mineral UV filters from the organic matrices, specific procedures such as solvent extraction were identified. In addition, several solvents (hexane, chloroform, dichloromethane, and tetrahydrofuran) have been investigated. The solvent extraction using tetrahydrofuran worked well for all the samples investigated. The isolated nanoparticles were characterized by using several different techniques such as transmission electron microscopy, scanning electron microscopy, dynamic light scattering, differential centrifugal sedimentation, and x-ray diffraction. Elemental analysis mapping studies were performed to obtain individual chemical and morphological identities of the nanoparticles. Results from the electron microscopy techniques were compared against the bulk particle sizing techniques. All of the sunscreen products tested in this study were found to contain nanosized (≤100 nm) metal oxide particles with varied shapes and aspect ratios, and four among the 11 products were showed to have anatase TiO2.

  2. Shell biofilm-associated nitrous oxide production in marine molluscs

    DEFF Research Database (Denmark)

    Heisterkamp, I.M.; Schramm, Andreas; Larsen, Lone Heimann

    2013-01-01

    Emission of the greenhouse gas nitrous oxide (N2O) from freshwater and terrestrial invertebrates has exclusively been ascribed to N2O production by ingested denitrifying bacteria in the anoxic gut of the animals. Our study of marine molluscs now shows that also microbial biofilms on shell surfaces...... are important sites of N2O production. The shell biofilms of Mytilus edulis, Littorina littorea and Hinia reticulata contributed 18-94% to the total animal-associated N2O emission. Nitrification and denitrification were equally important sources of N2O in shell biofilms as revealed by 15N-stable isotope...... mollusc species. Ammonium excretion by the animals was found to be sufficient to sustain N2O production in the shell biofilm. Apparently, the animals provide a nutrient-enriched microenvironment that stimulates growth and N2O production of the shell biofilm. This animal-induced stimulation...

  3. Mo-V-Te-Nb oxides as catalysts for ethene production by oxidative dehydrogenation of ethane

    Energy Technology Data Exchange (ETDEWEB)

    Hartmann, D. [Technische Universitaet Muenchen, Garching (Germany). Dept. of Chemistry and Catalysis Research Center; Meiswinkel, A.; Thaller, C.; Bock, M.; Alvarado, L. [Linde AG, Pullach (Germany)

    2013-11-01

    The availability of ethane in shale gas, as well as the interest in valorising previously underutilized carbon feedstocks, makes the oxidative dehydrogenation (ODH) of ethane an attractive alternative to the industrially established processes for production of ethylene. Mo-V-Te-Nb mixed oxide has been chosen as catalyst for the ODH reaction in view of its outstanding ability to activate alkane molecules. Catalytic test results showed that this type of catalyst can selectively oxidize ethane to ethene at moderate temperatures (350-400 C) with minor production of CO{sub x}. The catalytic performance of Mo-V-Te-Nb mixed-oxide is mainly attributable to the crystalline phase 'M1'. Rietveld analysis of the X-Ray diffractograms allowed us to quantify the amount of MoVTeNb oxide that has crystallized as M1. In this way, it was possible to find a linear correlation of the reaction rate with the abundance of M1 in the solid. Therefore, it is clear that for improving the efficiency of MoVTeNb oxide in ODH, the amount of M1 in the catalyst should be maximized. With this purpose, several MoVTeNb oxides were subject to different thermal treatments prior to the catalytic test. Structural changes in the catalyst were monitored by in-situ XRD technique. Under oxidative atmosphere, it was observed a recrystallization of M2 and possibly, amorphous oxide, into M1 phase, leading to correspondingly more active and selective catalysts (selectivities above 95 % for ethane conversions up to 40 % under industrially relevant conditions). The active site of M1 involves V species, likely with redox properties enhanced by the proximity of Mo and Te species, while the function of the crystalline structure itself is to provide the spatial configuration that allows interaction between these species. However, ethene formation rate was observed to be independent of the V content of the samples. The vanadium species exposed at the surface were studied by LEIS and by IR spectroscopy of CO

  4. Arginase expression modulates nitric oxide production in Leishmania (Leishmania) amazonensis.

    Science.gov (United States)

    Acuña, Stephanie Maia; Aoki, Juliana Ide; Laranjeira-Silva, Maria Fernanda; Zampieri, Ricardo Andrade; Fernandes, Juliane Cristina Ribeiro; Muxel, Sandra Marcia; Floeter-Winter, Lucile Maria

    2017-01-01

    Arginase is an enzyme that converts L-arginine to urea and L-ornithine, an essential substrate for the polyamine pathway supporting Leishmania (Leishmania) amazonensis replication and its survival in the mammalian host. L-arginine is also the substrate of macrophage nitric oxide synthase 2 (NOS2) to produce nitric oxide (NO) that kills the parasite. This competition can define the fate of Leishmania infection. The transcriptomic profiling identified a family of oxidoreductases in L. (L.) amazonensis wild-type (La-WT) and L. (L.) amazonensis arginase knockout (La-arg-) promastigotes and axenic amastigotes. We highlighted the identification of an oxidoreductase that could act as nitric oxide synthase-like (NOS-like), due to the following evidences: conserved domain composition, the participation of NO production during the time course of promastigotes growth and during the axenic amastigotes differentiation, regulation dependence on arginase activity, as well as reduction of NO amount through the NOS activity inhibition. NO quantification was measured by DAF-FM labeling analysis in a flow cytometry. We described an arginase-dependent NOS-like activity in L. (L.) amazonensis and its role in the parasite growth. The increased detection of NO production in the mid-stationary and late-stationary growth phases of La-WT promastigotes could suggest that this production is an important factor to metacyclogenesis triggering. On the other hand, La-arg- showed an earlier increase in NO production compared to La-WT, suggesting that NO production can be arginase-dependent. Interestingly, La-WT and La-arg- axenic amastigotes produced higher levels of NO than those observed in promastigotes. As a conclusion, our work suggested that NOS-like is expressed in Leishmania in the stationary growth phase promastigotes and amastigotes, and could be correlated to metacyclogenesis and amastigotes growth in a dependent way to the internal pool of L-arginine and arginase activity.

  5. Photoelectrochemical and electrocatalytic properties of thermally oxidized copper oxide for efficient solar fuel production

    KAUST Repository

    Garcia Esparza, Angel T.; Limkrailassiri, Kevin; Leroy, Fré dé ric; Rasul, Shahid; Yu, Weili; Lin, Liwei; Takanabe, Kazuhiro

    2014-01-01

    We report the use of a facile and highly scalable synthesis process to control growth products of earth-abundant Cu-based oxides and their application in relevant photoelectrochemical and electrochemical solar fuel generation systems. Characterization of the synthesized Cu(I)/Cu(II) oxides indicates that their surface morphology and chemical composition can be simply tuned by varying two synthesis parameters (time and temperature). UV-Vis spectroscopy and impedance spectroscopy studies are performed to estimate the band structures and electronic properties of these p-type semiconductor materials. Photoelectrodes made of Cu oxides possess favorable energy band structures for production of hydrogen from water; the position of their conduction band is ≈1 V more negative than the water-reduction potential. High acceptor concentrations on the order of 1018-1019 cm-3 are obtained, producing large electric fields at the semiconductor-electrolyte interface and thereby enhancing charge separation. The highly crystalline pristine samples used as photocathodes in photoelectrochemical cells exhibit high photocurrents under AM 1.5G simulated illumination. When the samples are electrochemically reduced under galvanostatic conditions, the co-existence of the oxide with metallic Cu on the surface seems to function as an effective catalyst for the selective electrochemical reduction of CO2. © the Partner Organisations 2014.

  6. Polycyclic aromatic hydrocarbons (PAHs) degradation by laccase ...

    African Journals Online (AJOL)

    PRECIOUS

    2009-11-02

    Nov 2, 2009 ... Full Length Research Paper. Polycyclic aromatic ... production of paper, feeds, chemicals and fuels there is ... microbes with the production of lignin-modifying enzymes ... enable white rot fungi to degrade a variety of toxic.

  7. PYROLYSIS OF ISOCHRYSIS MICROALGAE WITH METAL OXIDE CATALYSTS FOR BIO-OIL PRODUCTION

    Directory of Open Access Journals (Sweden)

    TEVFİK AYSU

    2016-12-01

    Full Text Available Pyrolysis of Isochrysis microalgae was carried out in a fixed-bed reactor without and with metal oxide catalysts (CeO2, TiO2, Al2O3 at the temperatures of 450, 500 and 550 oC with a constant heating rate of 40 oC/min. The pyrolysis conditions including catalyst and temperature were studied in terms of their effects on the yields of pyrolysis products and quality. The amount of bio-char, bio-oil and gas products was calculated. The composition of the produced bio-oils was determined by Elemental analysis (EA, Fourier transform infrared spectroscopy (FT-IR, proton nuclear magnetic resonance (1H NMR and Gas chromatography/mass spectrometry (GC–MS techniques. As a result of the pyrolysis experiments, it is shown that there have been significant effects of both catalyst and temperature on the conversion of Isochrysis microalgae into solid, liquid (bio-oil and gas products. The highest bio-oil yield (24.30 % including aqueous phase was obtained in the presence of TiO2 (50% as catalyst at 500 °C. 98 different compounds were identified by GC-MS in bio-oils obtained at 500 oC. According to 1H NMR analysis, bio-oils contained ∼60-64 % aliphatic and ∼17-19 % aromatic structural units. EA showed that the bio-oils contained ∼66-69 % C and having 31-34 MJ/kg higher heating values.

  8. Oxidation kinetics of hydride-bearing uranium metal corrosion products

    Science.gov (United States)

    Totemeier, Terry C.; Pahl, Robert G.; Frank, Steven M.

    The oxidation behavior of hydride-bearing uranium metal corrosion products from Zero Power Physics Reactor (ZPPR) fuel plates was studied using thermo-gravimetric analysis (TGA) in environments of Ar-4%O 2, Ar-9%O 2, and Ar-20%O 2. Ignition of corrosion product samples from two moderately corroded plates was observed between 125°C and 150°C in all environments. The rate of oxidation above the ignition temperature was found to be dependent only on the net flow rate of oxygen in the reacting gas. Due to the higher net oxygen flow rate, burning rates increased with increasing oxygen concentration. Oxidation rates below the ignition temperature were much slower and decreased with increasing test time. The hydride contents of the TGA samples from the two moderately corroded plates, determined from the total weight gain achieved during burning, were 47-61 wt% and 29-39 wt%. Samples from a lightly corroded plate were not reactive; X-ray diffraction (XRD) confirmed that they contained little hydride.

  9. Oxidation kinetics of hydride-bearing uranium metal corrosion products

    International Nuclear Information System (INIS)

    Totemeier, T.C.; Pahl, R.G.; Frank, S.M.

    1998-01-01

    The oxidation behavior of hydride-bearing uranium metal corrosion products from zero power physics reactor (ZPPR) fuel plates was studied using thermo-gravimetric analysis (TGA) in environments of Ar-4%O 2 , Ar-9%O 2 , and Ar-20%O 2 . Ignition of corrosion product samples from two moderately corroded plates was observed between 125 C and 150 C in all environments. The rate of oxidation above the ignition temperature was found to be dependent only on the net flow rate of oxygen in the reacting gas. Due to the higher net oxygen flow rate, burning rates increased with increasing oxygen concentration. Oxidation rates below the ignition temperature were much slower and decreased with increasing test time. The hydride contents of the TGA samples from the two moderately corroded plates, determined from the total weight gain achieved during burning, were 47-61 wt% and 29-39 wt%. Samples from a lightly corroded plate were not reactive; X-ray diffraction (XRD) confirmed that they contained little hydride. (orig.)

  10. Measurements of photo-oxidation products from the reaction of a series of alkyl-benzenes with hydroxyl radicals during EXACT using comprehensive gas chromatography

    Directory of Open Access Journals (Sweden)

    J. F. Hamilton

    2003-01-01

    Full Text Available Photo-oxidation products from the reaction of a series of alkyl-benzenes, (benzene, toluene, p-xylene and 1,3,5-trimethyl-benzene with hydroxyl radicals in the presence of NOx have been investigated using comprehensive gas chromatography (GCxGC. A GCxGC system has been developed which utilises valve modulation and independent separations as a function of both volatility and polarity. A number of carbonyl-type compounds were identified during a series of reactions carried out at the European Photoreactor (EUPHORE, a large volume outdoor reaction chamber in Valencia, Spain. Experiments were carried as part of the EXACT project (Effects of the oXidation of Aromatic Compounds in the Troposphere. Two litre chamber air samples were cryo-focused, with a sampling frequency of 30 minutes, allowing the evolution of species to be followed over oxidation periods of 3-6 hours. To facilitate product identification, several carbonyl compounds, which were possible products of the photo-oxidation, were synthesised and used as reference standards. For toluene reactions, observed oxygenated intermediates found included the co-eluting pair a-angelicalactone/4-oxo-2-pentenal, maleic anhydride, citraconic anhydride, benzaldehyde and p-methyl benzoquinone. In the p-xylene experiment, the products identified were E/Z-hex-3-en-2,5-dione and citraconic anhydride. For 1,3,5-TMB reactions, the products identified were 3,5-dimethylbenzaldehyde, 3,5-dimethyl-3H-furan-2-one and 3-methyl-5-methylene-5H-furan-2-one. Preliminary quantification was carried out on identified compounds using liquid standards. Comparison of FTIR and GCxGC for the measurement of the parent aromatics generally showed good agreement. Comparison of the concentrations observed by GCxGC to concentration-time profiles simulated using the Master Chemical Mechanism, MCMv3, demonstrates that this mechanism significantly over-predicts the concentrations of many product compounds and highlights the

  11. Production of aromas and fragrances through microbial oxidation of monoterpenes

    Directory of Open Access Journals (Sweden)

    H. F. Rozenbaum

    2006-09-01

    Full Text Available Aromas and fragrances can be obtained through the microbial oxidation of monoterpenes. Many microorganisms can be used to carry out extremely specific conversions using substrates of low commercial value. However, for many species, these substrates are highly toxic, consequently inhibiting their metabolism. In this work, the conversion ability of Aspergillus niger IOC-3913 for terpenic compounds was examined. This species was preselected because of its high resistance to toxic monoterpenic substrates. Though it has been grown in media containing R-limonene (one of the cheapest monoterpenic hydrocarbons, which is widely available on the market, the species has not shown the ability to metabolize it, since biotransformation products were not detected in high resolution gas chromatography analyses. For this reason, other monoterpenes (alpha-pinene, beta-pinene and camphor were used as substrates. These compounds were shown to be metabolized by the selected strain, producing oxidized compounds. Four reaction systems were used: a biotransformation in a liquid medium with cells in growth b with pre-grown cultures c with cells immobilized in a synthetic polymer network and d in a solid medium to which the substrate was added via the gas phase. The main biotransformation products were found in all the reaction systems, although the adoption of previously cultivated cells seemed to favor biotransformation. Cell immobilization seemed to be a feasible strategy for alleviating the toxic effect of the substrate. Through mass spectrometry it was possible to identify verbenone and alpha-terpineol as the biotransformation products of alpha-pinene and beta-pinene, respectively. The structures of the other oxidation products are described.

  12. Genomic phenotyping by barcode sequencing broadly distinguishes between alkylating agents, oxidizing agents, and non-genotoxic agents, and reveals a role for aromatic amino acids in cellular recovery after quinone exposure.

    Science.gov (United States)

    Svensson, J Peter; Quirós Pesudo, Laia; McRee, Siobhan K; Adeleye, Yeyejide; Carmichael, Paul; Samson, Leona D

    2013-01-01

    Toxicity screening of compounds provides a means to identify compounds harmful for human health and the environment. Here, we further develop the technique of genomic phenotyping to improve throughput while maintaining specificity. We exposed cells to eight different compounds that rely on different modes of action: four genotoxic alkylating (methyl methanesulfonate (MMS), N-Methyl-N-nitrosourea (MNU), N,N'-bis(2-chloroethyl)-N-nitroso-urea (BCNU), N-ethylnitrosourea (ENU)), two oxidizing (2-methylnaphthalene-1,4-dione (menadione, MEN), benzene-1,4-diol (hydroquinone, HYQ)), and two non-genotoxic (methyl carbamate (MC) and dimethyl sulfoxide (DMSO)) compounds. A library of S. cerevisiae 4,852 deletion strains, each identifiable by a unique genetic 'barcode', were grown in competition; at different time points the ratio between the strains was assessed by quantitative high throughput 'barcode' sequencing. The method was validated by comparison to previous genomic phenotyping studies and 90% of the strains identified as MMS-sensitive here were also identified as MMS-sensitive in a much lower throughput solid agar screen. The data provide profiles of proteins and pathways needed for recovery after both genotoxic and non-genotoxic compounds. In addition, a novel role for aromatic amino acids in the recovery after treatment with oxidizing agents was suggested. The role of aromatic acids was further validated; the quinone subgroup of oxidizing agents were extremely toxic in cells where tryptophan biosynthesis was compromised.

  13. Genomic phenotyping by barcode sequencing broadly distinguishes between alkylating agents, oxidizing agents, and non-genotoxic agents, and reveals a role for aromatic amino acids in cellular recovery after quinone exposure.

    Directory of Open Access Journals (Sweden)

    J Peter Svensson

    Full Text Available Toxicity screening of compounds provides a means to identify compounds harmful for human health and the environment. Here, we further develop the technique of genomic phenotyping to improve throughput while maintaining specificity. We exposed cells to eight different compounds that rely on different modes of action: four genotoxic alkylating (methyl methanesulfonate (MMS, N-Methyl-N-nitrosourea (MNU, N,N'-bis(2-chloroethyl-N-nitroso-urea (BCNU, N-ethylnitrosourea (ENU, two oxidizing (2-methylnaphthalene-1,4-dione (menadione, MEN, benzene-1,4-diol (hydroquinone, HYQ, and two non-genotoxic (methyl carbamate (MC and dimethyl sulfoxide (DMSO compounds. A library of S. cerevisiae 4,852 deletion strains, each identifiable by a unique genetic 'barcode', were grown in competition; at different time points the ratio between the strains was assessed by quantitative high throughput 'barcode' sequencing. The method was validated by comparison to previous genomic phenotyping studies and 90% of the strains identified as MMS-sensitive here were also identified as MMS-sensitive in a much lower throughput solid agar screen. The data provide profiles of proteins and pathways needed for recovery after both genotoxic and non-genotoxic compounds. In addition, a novel role for aromatic amino acids in the recovery after treatment with oxidizing agents was suggested. The role of aromatic acids was further validated; the quinone subgroup of oxidizing agents were extremely toxic in cells where tryptophan biosynthesis was compromised.

  14. Oxidative Stress in Shiga Toxin Production by Enterohemorrhagic Escherichia coli

    Directory of Open Access Journals (Sweden)

    Katarzyna Licznerska

    2016-01-01

    Full Text Available Virulence of enterohemorrhagic Escherichia coli (EHEC strains depends on production of Shiga toxins. These toxins are encoded in genomes of lambdoid bacteriophages (Shiga toxin-converting phages, present in EHEC cells as prophages. The genes coding for Shiga toxins are silent in lysogenic bacteria, and prophage induction is necessary for their efficient expression and toxin production. Under laboratory conditions, treatment with UV light or antibiotics interfering with DNA replication are commonly used to induce lambdoid prophages. Since such conditions are unlikely to occur in human intestine, various research groups searched for other factors or agents that might induce Shiga toxin-converting prophages. Among other conditions, it was reported that treatment with H2O2 caused induction of these prophages, though with efficiency significantly lower relative to UV-irradiation or mitomycin C treatment. A molecular mechanism of this phenomenon has been proposed. It appears that the oxidative stress represents natural conditions provoking induction of Shiga toxin-converting prophages as a consequence of H2O2 excretion by either neutrophils in infected humans or protist predators outside human body. Finally, the recently proposed biological role of Shiga toxin production is described in this paper, and the “bacterial altruism” and “Trojan Horse” hypotheses, which are connected to the oxidative stress, are discussed.

  15. Requirement of argininosuccinate lyase for systemic nitric oxide production.

    Science.gov (United States)

    Erez, Ayelet; Nagamani, Sandesh C S; Shchelochkov, Oleg A; Premkumar, Muralidhar H; Campeau, Philippe M; Chen, Yuqing; Garg, Harsha K; Li, Li; Mian, Asad; Bertin, Terry K; Black, Jennifer O; Zeng, Heng; Tang, Yaoping; Reddy, Anilkumar K; Summar, Marshall; O'Brien, William E; Harrison, David G; Mitch, William E; Marini, Juan C; Aschner, Judy L; Bryan, Nathan S; Lee, Brendan

    2011-11-13

    Nitric oxide (NO) is crucial in diverse physiological and pathological processes. We show that a hypomorphic mouse model of argininosuccinate lyase (encoded by Asl) deficiency has a distinct phenotype of multiorgan dysfunction and NO deficiency. Loss of Asl in both humans and mice leads to reduced NO synthesis, owing to both decreased endogenous arginine synthesis and an impaired ability to use extracellular arginine for NO production. Administration of nitrite, which can be converted into NO in vivo, rescued the manifestations of NO deficiency in hypomorphic Asl mice, and a nitric oxide synthase (NOS)-independent NO donor restored NO-dependent vascular reactivity in humans with ASL deficiency. Mechanistic studies showed that ASL has a structural function in addition to its catalytic activity, by which it contributes to the formation of a multiprotein complex required for NO production. Our data demonstrate a previously unappreciated role for ASL in NOS function and NO homeostasis. Hence, ASL may serve as a target for manipulating NO production in experimental models, as well as for the treatment of NO-related diseases.

  16. A combined chemical + enzymatic method to remove selected aromatics from aqueous streams

    International Nuclear Information System (INIS)

    Xu, X.; John, V.

    1993-01-01

    Aromatics are major pollutants found in aqueous environments and in sediments. While there are many chemical and biochemical processes to remove and/or destroy these contaminants, they have to be considered in light of the economics and the time-scales for treatment. We describe our initial work on a hybrid chemical + enzymatic technique to remove aromatics from aqueous stream. The aromatic is first converted to the corresponding phenol through classical Fenton type chemistry involving catalysis by Fe(II). The phenol is subsequently polymerized through an enzymatic mechanism, using horseradish peroxidase as the oxidative enzyme. The polymer is insoluble in water and can be easily recovered. In addition, such phenolic polymers are useful products with varied applications in coatings and resin technologies. Thus, the pollutants can be eventually converted to useful products

  17. Production and analysis of ultradispersed uranium oxide powders

    Science.gov (United States)

    Zajogin, A. P.; Komyak, A. I.; Umreiko, D. S.; Umreiko, S. D.

    2010-05-01

    Spectroscopic studies are made of the laser plasma formed near the surface of a porous body containing nanoquantities of uranium compounds which is irradiated by two successive laser pulses. The feasibility of using laser chemical methods for obtaining nanoclusters of uranium oxide particles in the volume of a porous body and the simultaneous possibility of determining the uranium content with good sensitivity are demonstrated. The thermochemical and spectral characteristics of the analogs of their compounds with chlorine are determined and studied. The possibility of producing uranium dioxides under ordinary conditions and their analysis in the reaction products is demonstrated.

  18. Identification of intermediates and assessment of ecotoxicity in the oxidation products generated during the ozonation of clofibric acid.

    Science.gov (United States)

    Rosal, Roberto; Gonzalo, María S; Boltes, Karina; Letón, Pedro; Vaquero, Juan J; García-Calvo, E

    2009-12-30

    The degradation of an aqueous solution of clofibric acid was investigated during catalytic and non-catalytic ozonation. The catalyst, TiO(2), enhanced the production of hydroxyl radicals from ozone and raised the fraction or clofibric acid degraded by hydroxyl radicals. The rate constant for the reaction of clofibric acid and hydroxyl radicals was not affected by the presence of the catalyst. The toxicity of the oxidation products obtained during the reaction was assessed by means of Vibrio fischeri and Daphnia magna tests in order to evaluate the potential formation of toxic by-products. The results showed that the ozonation was enhanced by the presence of TiO(2,) the clofibric acid being removed completely after 15 min at pH 5. The evolution of dissolved organic carbon, specific ultraviolet absorption at 254 nm and the concentration of carboxylic acids monitored the degradation process. The formation of 4-chlorophenol, hydroquinone, 4-chlorocatechol, 2-hydroxyisobutyric acid and three non-aromatic compounds identified as a product of the ring-opening reaction was assessed by exact mass measurements performed by liquid chromatography coupled to time-of-flight mass spectrometry (LC-TOF-MS). The bioassays showed a significant increase in toxicity during the initial stages of ozonation following a toxicity pattern closely related to the formation of ring-opening by-products.

  19. Microarc Oxidation of Product Surfaces without Using a Bath

    Directory of Open Access Journals (Sweden)

    V. K. Shatalov

    2015-01-01

    Full Text Available While using an electrochemical method to cover the large-sized work-pieces, units, and products up to 6 м3 by protective coating, there is a certain difficulty to apply traditional anodizing techniques in a plating vat, and it is necessary to find various processing techniques.To use the existing micro-arc oxide coating (MOC methods for work-pieces of various forms and sizes in a plating vat is complicated in case it is required to provide oxide layers in separate places rather than over entire surface of a work-piece. The challenge is to treat flat surfaces in various directions, external and internal surfaces of rotation bodies, profiled surfaces, intersections, closed and through holes, pipes, as well as spline and thread openings for ensuring anti-seize properties in individual or small-scale production to meet technical requirements and operational properties of products.A design of tools to provide MOC-process of all possible surfaces of various engineering box-type products depends on many factors and can be considerably different even when processing the surfaces of the same forms. An attachment to be used is fixed directly on a large-sized design (a work-piece, a product or fastened in the special tool. The features of technological process, design shape, and arrangement of the processed surfaces define a fastening method of the attachment. Therefore it is necessary to pay much attention to a choice of the processing pattern and a design of tools.The Kaluga-branch of Bauman Moscow State Technical University is an original proposer of methods to form MOC-coatings on the separate surfaces of large-sized work-pieces using the moved and stationary electrodes to solve the above listed tasks.The following results of work will have an impact on development of the offered processing methods and their early implementation in real production:1. To provide oxide coatings on the surfaces of large-sized products or assemblies in a single or small

  20. Aerobic nitrous oxide production through N-nitrosating hybrid formation in ammonia-oxidizing archaea.

    Science.gov (United States)

    Stieglmeier, Michaela; Mooshammer, Maria; Kitzler, Barbara; Wanek, Wolfgang; Zechmeister-Boltenstern, Sophie; Richter, Andreas; Schleper, Christa

    2014-05-01

    Soil emissions are largely responsible for the increase of the potent greenhouse gas nitrous oxide (N2O) in the atmosphere and are generally attributed to the activity of nitrifying and denitrifying bacteria. However, the contribution of the recently discovered ammonia-oxidizing archaea (AOA) to N2O production from soil is unclear as is the mechanism by which they produce it. Here we investigate the potential of Nitrososphaera viennensis, the first pure culture of AOA from soil, to produce N2O and compare its activity with that of a marine AOA and an ammonia-oxidizing bacterium (AOB) from soil. N. viennensis produced N2O at a maximum yield of 0.09% N2O per molecule of nitrite under oxic growth conditions. N2O production rates of 4.6±0.6 amol N2O cell(-1) h(-1) and nitrification rates of 2.6±0.5 fmol NO2(-) cell(-1) h(-1) were in the same range as those of the AOB Nitrosospira multiformis and the marine AOA Nitrosopumilus maritimus grown under comparable conditions. In contrast to AOB, however, N2O production of the two archaeal strains did not increase when the oxygen concentration was reduced, suggesting that they are not capable of denitrification. In (15)N-labeling experiments we provide evidence that both ammonium and nitrite contribute equally via hybrid N2O formation to the N2O produced by N. viennensis under all conditions tested. Our results suggest that archaea may contribute to N2O production in terrestrial ecosystems, however, they are not capable of nitrifier-denitrification and thus do not produce increasing amounts of the greenhouse gas when oxygen becomes limiting.

  1. Regulation of adrenomedullin and nitric oxide production by periodontal bacteria.

    Science.gov (United States)

    Hussain, Q A; McKay, I J; Gonzales-Marin, C; Allaker, R P

    2015-10-01

    In periodontitis the host response to bacterial challenge includes activity of the multifunctional molecules adrenomedullin (AM) and nitric oxide (NO). The aim of this study was to investigate the role of periodontal bacteria in regulating the production of these molecules from cultured cells. Regulation of AM and NO production from oral keratinocytes when challenged with culture supernatants from Aggregatibacter actinomycetemcomitans, Campylobacter rectus, Fusobacterium nucleatum, Porphyromonas gingivalis, Prevotella intermedia, Veillonella atypica, Streptococcus salivarius and Candida albicans was examined. AM and NO were measured in cell culture supernatants using an enzyme-linked immunosorbent assay and the nitrate/nitrite (NO metabolites) Griess assay respectively. Cellular production of AM and inducible NO synthase was also analysed in target cells by immunofluorescence and Western blot analysis. The inter-relationship of AM and NO production were further investigated with macrophages. A. actinomycetemcomitans and C. rectus induced maximal levels of both AM and NO after 6 and 48 h respectively from oral keratinocytes. AM production in macrophages was upregulated in response to the NO donor S-nitrosoglutathione and partially blocked by the inducible NO synthase inhibitor, N(ω) -Nitro-l-arginine methyl ester hydrochloride. Likewise, NO production was increased upon exposure to AM, while the AM receptor antagonist AM 22-52 reduced the release of NO. Pathogens associated with aggressive periodontitis, A. actinomycetemcomitans and C. rectus, were more effective than those associated with chronic periodontitis, P. gingivalis and Prev. intermedia, and commensals, S. salivarius and V. atypica, as regards the upregulation of AM and NO production from oral keratinocytes. Interaction between these molecules was also demonstrated with macrophages. Understanding the coordinated regulation of AM and NO production in response to periodontal bacteria may identify

  2. Coupling Solid Oxide Electrolyser (SOE) and ammonia production plant

    International Nuclear Information System (INIS)

    Cinti, Giovanni; Frattini, Domenico; Jannelli, Elio; Desideri, Umberto; Bidini, Gianni

    2017-01-01

    Highlights: • An innovative NH 3 production plant was designed. • CO 2 emissions and energy consumption are studied in three different designs. • High temperature electrolysis allows to achieve high efficiency and heat recovery. • The coupling permits storage of electricity into a liquid carbon free chemical. - Abstract: Ammonia is one of the most produced chemicals worldwide and is currently synthesized using nitrogen separated from air and hydrogen from natural gas reforming with consequent high consumption of fossil fuel and high emission of CO 2 . A renewable path for ammonia production is desirable considering the potential development of ammonia as energy carrier. This study reports design and analysis of an innovative system for the production of green ammonia using electricity from renewable energy sources. This concept couples Solid Oxide Electrolysis (SOE), for the production of hydrogen, with an improved Haber Bosch Reactor (HBR), for ammonia synthesis. An air separator is also introduced to supply pure nitrogen. SOE operates with extremely high efficiency recovering high temperature heat from the Haber-Bosch reactor. Aspen was used to develop a model to study the performance of the plant. Both the SOE and the HBR operate at 650 °C. Ammonia production with zero emission of CO 2 can be obtained with a reduction of 40% of power input compared to equivalent plants.

  3. Use of calcium oxide in palm oil methyl ester production

    Directory of Open Access Journals (Sweden)

    Kulchanat Prasertsit

    2014-04-01

    Full Text Available Introducing an untreated calcium oxide (CaO as a solid heterogeneous catalyst for biodiesel production from palm oil by transesterification was studied in this work. The four studied parameters were methanol to oil molar ratio, CaO catalyst concentration, reaction time, and water content. The results for palm oil show that when the water content is higher than 3%wt and the amount of CaO greater than 7%wt soap formation from saponification occurs. A higher methanol to oil molar ratio requires a higher amount of CaO catalyst to provide the higher product purity. The appropriate methanol to CaO catalyst ratio is about 1.56. Commercial grade CaO gives almost the same results as AR grade CaO. In addition, reusing commercial grade CaO for about 5 to 10 repetitions without catalyst regeneration drops the percentage of methyl ester purity approximately 5 to 10%, respectively.

  4. Evaluating four mathematical models for nitrous oxide production by autotrophic ammonia-oxidizing bacteria.

    Science.gov (United States)

    Ni, Bing-Jie; Yuan, Zhiguo; Chandran, Kartik; Vanrolleghem, Peter A; Murthy, Sudhir

    2013-01-01

    There is increasing evidence showing that ammonia-oxidizing bacteria (AOB) are major contributors to N(2)O emissions from wastewater treatment plants (WWTPs). Although the fundamental metabolic pathways for N(2)O production by AOB are now coming to light, the mechanisms responsible for N(2)O production by AOB in WWTP are not fully understood. Mathematical modeling provides a means for testing hypotheses related to mechanisms and triggers for N(2)O emissions in WWTP, and can then also become a tool to support the development of mitigation strategies. This study examined the ability of four mathematical model structures to describe two distinct mechanisms of N(2)O production by AOB. The production mechanisms evaluated are (1) N(2)O as the final product of nitrifier denitrification with NO(2)- as the terminal electron acceptor and (2) N(2)O as a byproduct of incomplete oxidation of hydroxylamine (NH(2)OH) to NO(2)-. The four models were compared based on their ability to predict N(2)O dynamics observed in three mixed culture studies. Short-term batch experimental data were employed to examine model assumptions related to the effects of (1) NH4+ concentration variations, (2) dissolved oxygen (DO) variations, (3) NO(2)- accumulations and (4) NH(2OH as an externally provided substrate. The modeling results demonstrate that all these models can generally describe the NH4+, NO(2)-, and NO(3)- data. However, none of these models were able to reproduce all measured N(2)O data. The results suggest that both the denitrification and NH(2)OH pathways may be involved in N(2)O production and could be kinetically linked by a competition for intracellular reducing equivalents. A unified model capturing both mechanisms and their potential interactions needs to be developed with consideration of physiological complexity. Copyright © 2012 Wiley Periodicals, Inc.

  5. Products of BVOC oxidation: ozone and organic aerosols

    Science.gov (United States)

    Wildt, Jürgen; Andres, Stefanie; Carriero, Giulia; Ehn, Mikael; Fares, Silvano; Hoffmann, Thorsten; Hacker, Lina; Kiendler-Scharr, Astrid; Kleist, Einhard; Paoletti, Elena; Pullinen, Iida; Rohrer, Franz; Rudich, Yinon; Springer, Monika; Tillmann, Ralf; Wahner, Andreas; Wu, Cheng; Mentel, Thomas

    2015-04-01

    Biogenic Volatile Organic Compounds (BVOC) are important precursors in photochemical O3 and secondary organic aerosol (SOA) formation. We conducted a series of laboratory experiments with OH-induced oxidation of monoterpenes to elucidate pathways and efficiencies of O3 and SOA formation. At high NOx conditions ([BVOC] / [NOx] monoterpene mixes emitted from different plant species we observed increasing ozone formation with increasing [NOX]. Between 2 and 3 O3-molecules were formed from 1 monoterpene when ozone formation was BVOC limited. Under such high NOX conditions, new particle formation was suppressed. Increasing [BVOC] / [NOX] ratios caused increasing efficiency of new particle formation indicating that peroxy radicals are the key intermediates in both, photochemical ozone- and new particle formation. The classical chemistry of peroxy radicals is well established (e.g. Master Chemical Mechanism). Peroxy radicals are produced by addition of molecular oxygen to the alkyl radical formed after OH attack at the BVOC. They either react with NO which leads to ozone formation or they react with other peroxy radicals and form chemically stable products (hydroperoxides, alkoholes and ketones). Much less knowledge exists on such reactions for Highly Oxidized Peroxy Radicals, (HOPR). Such HOPR were observed during ozonolysis of several volatiles and, in case of monoterpenes as precursors, they can contain more than 12 Oxygen atoms (Mentel et al., 2015). Although the OH-initiated formation of HOPR is yet not fully understood, their basic gas phase reactions seem to follow classical photochemical rules. In reactions with NO they can act as precursor for O3 and in reactions with other HOPR or with classical less oxidized peroxy radicals they can form highly oxidized stable products and alkoxy radicals. In addition, HOPR-HOPR reactions lead to the formation of dimers that, in case of monoterpenes as reactants, consist of a skeleton with 20 carbon atoms. These dimers seem to

  6. Yttrium bismuth titanate pyrochlore mixed oxides for photocatalytic hydrogen production

    Energy Technology Data Exchange (ETDEWEB)

    Merka, Oliver

    2012-10-18

    In this work, the sol-gel synthesis of new non-stoichiometric pyrochlore titanates and their application in photocatalytic hydrogen production is reported. Visible light response is achieved by introducing bismuth on the A site or by doping the B site by transition metal cations featuring partially filled d orbitals. This work clearly focusses on atomic scale structural changes induced by the systematical introduction of non-stoichiometry in pyrochlore mixed oxides and the resulting influence on the activity in photocatalytic hydrogen production. The materials were characterized in detail regarding their optical properties and their atomic structure. The pyrochlore structure tolerates tremendous stoichiometry variations. The non-stoichiometry in A{sub 2}O{sub 3} rich compositions is compensated by distortions in the cationic sub-lattice for the smaller Y{sup 3+} cation and by evolution of a secondary phase for the larger Bi{sup 3+} cation on the A site. For TiO{sub 2} rich compositions, the non-stoichiometry leads to a special vacancy formation in the A and optionally O' sites. It is shown that pyrochlore mixed oxides in the yttrium bismuth titanate system represent very active and promising materials for photocatalytic hydrogen production, if precisely and carefully tuned. Whereas Y{sub 2}Ti{sub 2}O{sub 7} yields stable hydrogen production rates over time, the bismuth richer compounds of YBiTi{sub 2}O{sub 7} and Bi{sub 2}Ti{sub 2}O{sub 7} are found to be not stable under irradiation. This drawback is overcome by applying a special co-catalyst system consisting of a precious metal core and a Cr{sub 2}O{sub 3} shell on the photocatalysts.

  7. Wet oxidation pretreatment of rape straw for ethanol production

    International Nuclear Information System (INIS)

    Arvaniti, Efthalia; Bjerre, Anne Belinda; Schmidt, Jens Ejbye

    2012-01-01

    Rape straw can be used for production of second generation bioethanol. In this paper we optimized the pretreatment of rape straw for this purpose using Wet oxidation (WO). The effect of reaction temperature, reaction time, and oxygen gas pressure was investigated for maximum ethanol yield via Simultaneous Saccharification and Fermentation (SSF). To reduce the water use and increase the energy efficiency in WO pretreatment features like recycling liquid (filtrate), presoaking of rape straw in water or recycled filtrate before WO, skip washing pretreated solids (filter cake) after WO, or use of whole slurry (Filter cake + filtrate) in SSF were also tested. Except ethanol yields, pretreatment methods were evaluated based on achieved glucose yields, amount of water used, recovery of cellulose, hemicellulose, and lignin. The highest ethanol yield obtained was 67% after fermenting the whole slurry produced by WO at 205 °C for 3 min with 12 bar of oxygen gas pressure and featured with presoaking in water. At these conditions after pre-treatment, cellulose and hemicellulose was recovered quantitatively (100%) together with 86% of the lignin. WO treatments of 2–3 min at 205–210 °C with 12 bar of oxygen gas produced higher ethanol yields and cellulose, hemicelluloses, and lignin recoveries, than 15 min WO treatment at 195 °C. Also, recycling filtrate and use of higher oxygen gas pressure reduced recovery of materials. The use of filtrate could be inhibitory for the yeast, but also reduced lactic acid formation in SSF. -- Highlights: ► Wet Oxidation pretreatment on rape straw for sugar and ethanol production. ► Variables were reaction time, temperature, and oxygen gas pressure. ► Also, other configurations for increase of water and energy efficiency. ► Short Wet oxidation pretreatment (2–3 min) produced highest ethanol yield. ► After these pretreatment conditions recovery of lignin in solids was 86%.

  8. Solar Thermochemical Hydrogen Production via Terbium Oxide Based Redox Reactions

    Directory of Open Access Journals (Sweden)

    Rahul Bhosale

    2016-01-01

    Full Text Available The computational thermodynamic modeling of the terbium oxide based two-step solar thermochemical water splitting (Tb-WS cycle is reported. The 1st step of the Tb-WS cycle involves thermal reduction of TbO2 into Tb and O2, whereas the 2nd step corresponds to the production of H2 through Tb oxidation by water splitting reaction. Equilibrium compositions associated with the thermal reduction and water splitting steps were determined via HSC simulations. Influence of oxygen partial pressure in the inert gas on thermal reduction of TbO2 and effect of water splitting temperature (TL on Gibbs free energy related to the H2 production step were examined in detail. The cycle (ηcycle and solar-to-fuel energy conversion (ηsolar-to-fuel efficiency of the Tb-WS cycle were determined by performing the second-law thermodynamic analysis. Results obtained indicate that ηcycle and ηsolar-to-fuel increase with the decrease in oxygen partial pressure in the inert flushing gas and thermal reduction temperature (TH. It was also realized that the recuperation of the heat released by the water splitting reactor and quench unit further enhances the solar reactor efficiency. At TH=2280 K, by applying 60% heat recuperation, maximum ηcycle of 39.0% and ηsolar-to-fuel of 47.1% for the Tb-WS cycle can be attained.

  9. Nitrous oxide production kinetics during nitrate reduction in river sediments.

    Science.gov (United States)

    Laverman, Anniet M; Garnier, Josette A; Mounier, Emmanuelle M; Roose-Amsaleg, Céline L

    2010-03-01

    A significant amount of nitrogen entering river basins is denitrified in riparian zones. The aim of this study was to evaluate the influence of nitrate and carbon concentrations on the kinetic parameters of nitrate reduction as well as nitrous oxide emissions in river sediments in a tributary of the Marne (the Seine basin, France). In order to determine these rates, we used flow-through reactors (FTRs) and slurry incubations; flow-through reactors allow determination of rates on intact sediment slices under controlled conditions compared to sediment homogenization in the often used slurry technique. Maximum nitrate reduction rates (R(m)) ranged between 3.0 and 7.1microg Ng(-1)h(-1), and affinity constant (K(m)) ranged from 7.4 to 30.7mg N-NO(3)(-)L(-1). These values were higher in slurry incubations with an R(m) of 37.9microg Ng(-1)h(-1) and a K(m) of 104mg N-NO(3)(-)L(-1). Nitrous oxide production rates did not follow Michaelis-Menten kinetics, and we deduced a rate constant with an average of 0.7 and 5.4ng Ng(-1)h(-1) for FTR and slurry experiments respectively. The addition of carbon (as acetate) showed that carbon was not limiting nitrate reduction rates in these sediments. Similar rates were obtained for FTR and slurries with carbon addition, confirming the hypothesis that homogenization increases rates due to release of and increasing access to carbon in slurries. Nitrous oxide production rates in FTR with carbon additions were low and represented less than 0.01% of the nitrate reduction rates and were even negligible in slurries. Maximum nitrate reduction rates revealed seasonality with high potential rates in fall and winter and low rates in late spring and summer. Under optimal conditions (anoxia, non-limiting nitrate and carbon), nitrous oxide emission rates were low, but significant (0.01% of the nitrate reduction rates). Copyright 2009 Elsevier Ltd. All rights reserved.

  10. Doxycycline reduces nitric oxide production in guinea pig inner ears.

    Science.gov (United States)

    Helling, Kai; Wodarzcyk, Karl; Brieger, Jürgen; Schmidtmann, Irene; Li, Huige; Mann, Wolf J; Heinrich, Ulf-Rüdiger

    2011-12-01

    Gentamicin application is an important therapeutic option to control vertigo spells in Ménière's disease. However, even in the case of low-dose intratympanic application, gentamicin might contribute to a pathological NO-increase leading to cochlear damage and hearing impairment. The study was performed to evaluate the nitric oxide (NO) reducing capacity of doxycycline in the inner ear after NO-induction by gentamicin. In a prospective animal study, a single dose of gentamicin (10mg/kg body weight) was injected intratympanically into male guinea pigs (n=48). The auditory brainstem responses (ABRs) were recorded prior to application and 3, 5 and 7 days afterwards. The organ of Corti and the lateral wall of 42 animals were isolated after 7 days and incubated separately for 6h in cell culture medium. Doxycycline was adjusted to organ cultures of 5 animals. Two NOS inhibitors, N(G)-Nitro-l-arginine methyl ester (l-NAME) and NG-monomethyl-l-arginine monoacetate (l-NMMA), were applied in three different concentrations to the organ cultures of 30 animals in total (5 animals per concentration). As controls, seven animals received no further substance except gentamicin. The NO-production was quantified by chemiluminescence. Additional six gentamicin-treated animals were used for immunohistochemical studies. The ABRs declined continuously from the first to the seventh day after gentamicin application. Doxycycline reduced NO-production in the lateral wall by 54% (p=.029) comparable to the effect of the applied nitric oxide inhibitors. In the organ of Corti, NO-production was reduced by about 41% showing no statistical significance in respect to great inter-animal variations. The application of doxycycline might offer a new therapeutic approach to prevent NO-induced cochlea damage through ototoxic substances. Copyright © 2011 Elsevier Ireland Ltd. All rights reserved.

  11. 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.

  12. Efficient production of ultrapure manganese oxides via electrodeposition.

    Science.gov (United States)

    Cheney, Marcos A; Joo, Sang Woo; Banerjee, Arghya; Min, Bong-Ki

    2012-08-01

    A new process for the production of electrolytic amorphous nanomanganese oxides (EAMD) with uniform size and morphology is described. EAMD are produced for the first time by cathodic deposition from a basic aqueous solution of potassium permanganate at a constant temperature of 16°C. The synthesized materials are characterized by XRD, SEM, TEM, and HRTEM. The materials produced at 5.0 V at constant temperature are amorphous with homogeneous size and morphology with an average particle size around 20 nm, which appears to be much lesser than the previously reported anodic EAMD. A potentiostatic electrodeposition with much lesser deposition rate (with respect to previously reported anodic depositions) is considered to be the reason behind the very low and homogenous particle size distribution due to the lesser agglomeration of our as-synthesized nanoparticles. Copyright © 2012 Elsevier Inc. All rights reserved.

  13. Production of zinc oxide nanowires power with precisely defined morphology

    Science.gov (United States)

    Mičová, Júlia; Remeš, Zdeněk; Chan, Yu-Ying

    2017-12-01

    The interest about zinc oxide is increasing thanks to its unique chemical and physical properties. Our attention has focused on preparation powder of 1D nanostructures of ZnO nanowires with precisely defined morphology include characterization size (length and diameter) and shape controlled in the scanning electron microscopy (SEM). We have compared results of SEM with dynamic light scattering (DLS) technique. We have found out that SEM method gives more accurate results. We have proposed transformation process from ZnO nanowires on substrates to ZnO nanowires powder by ultrasound peeling to colloid followed by lyophilization. This method of the mass production of the ZnO nanowires powder has some advantages: simplicity, cost effective, large-scale and environment friendly.

  14. Wet oxidation pretreatment of rape straw for ethanol production

    DEFF Research Database (Denmark)

    Arvaniti, Efthalia; Bjerre, Anne Belinda; Schmidt, Jens Ejbye

    2012-01-01

    Rape straw can be used for production of second generation bioethanol. In this paper we optimized the pretreatment of rape straw for this purpose using Wet oxidation (WO). The effect of reaction temperature, reaction time, and oxygen gas pressure was investigated for maximum ethanol yield via...... Simultaneous Saccharification and Fermentation (SSF). To reduce the water use and increase the energy efficiency in WO pretreatment features like recycling liquid (filtrate), presoaking of rape straw in water or recycled filtrate before WO, skip washing pretreated solids (filter cake) after WO, or use of whole...... gas produced higher ethanol yields and cellulose, hemicelluloses, and lignin recoveries, than 15 min WO treatment at 195 °C. Also, recycling filtrate and use of higher oxygen gas pressure reduced recovery of materials. The use of filtrate could be inhibitory for the yeast, but also reduced lactic acid...

  15. Additive effects of CuSO4 and aromatic compounds on laccase production by Pleurotus sajor-caju PS-2001 using sucrose as a carbon source

    Directory of Open Access Journals (Sweden)

    F. Bettin

    2014-06-01

    Full Text Available Laccase enzymes are now commercially available, and a laccase/mediator combination is currently marketed for indigo dye bleaching in textile manufacturing; replacing traditional chemical-based processes with enzymatic technology reduces the need for effluent treatment. However, an inexpensive source of these enzymes will be needed to enable wider application of this technology. In the present work, the main objective was to increase laccase production by the mushroom Pleurotus sajor-caju strain PS-2001 grown on sucrose derived from sugar cane, one of most economical carbon sources known, by the addition of compounds that are known to affect laccase production. High laccase activities (45-62 U mL-1 were obtained with additions of syringaldazine, benzoic acid, gallic acid, and vanillin. When CuSO4 was used in conjunction with these aromatic compounds, the levels of laccase activity were further improved, reaching 58-80 U mL-1. These laccase activities indicate the potential of this strain as an enzyme producer, which has also been detected in media containing glucose, but with activity lower than that observed with sucrose.

  16. Arbuscular mycorrhizal fungi are an alternative to the application of chemical fertilizer in the production of the medicinal and aromatic plant Coriandrum sativum L.

    Science.gov (United States)

    Oliveira, Rui S; Ma, Ying; Rocha, Inês; Carvalho, Maria F; Vosátka, Miroslav; Freitas, Helena

    2016-01-01

    The widespread use of agrochemicals is detrimental to the environment and may exert harmful effects on human health. The consumer demand for organic food plants has been increasing. There is thus a rising need for alternatives to agrochemicals that can foster sustainable plant production. The aim of this study was to evaluate the potential use of an arbuscular mycorrhizal (AM) fungus as an alternative to application of chemical fertilizer for improving growth performance of the medicinal and aromatic plant Coriandrum sativum. Plants were inoculated with the AM fungus Rhizophagus irregularis BEG163 and/or supplemented with a commercial chemical fertilizer (Plant Marvel, Nutriculture Bent Special) in agricultural soil. Plant growth, nutrition, and development of AM fungus were assessed. Plants inoculated with R. irregularis and those supplemented with chemical fertilizer displayed significantly improved growth performances when compared with controls. There were no significant differences in total fresh weight between plants inoculated with R. irregularis or those supplemented with chemical fertilizer. Leaf chlorophyll a + b (82%), shoot nitrogen (44%), phosphorus (254%), and potassium (27%) concentrations increased in plants inoculated with R. irregularis compared to controls. Application of chemical fertilizer inhibited root mycorrhizal colonization and the length of the extraradical mycelium of R. irregularis. Inoculation with R. irregularis was equally or more efficient than application of chemical fertilizer in promoting growth and nutrition of C. sativum. AM fungi may thus contribute to improve biologically based production of food plants and reduce the dependence on agrochemicals in agriculture.

  17. Influence of the method of production of eggs on the daily intake of polycyclic aromatic hydrocarbons and organochlorine contaminants: an independent study in the Canary Islands (Spain).

    Science.gov (United States)

    Luzardo, Octavio P; Rodríguez-Hernández, Angel; Quesada-Tacoronte, Yohana; Ruiz-Suárez, Norberto; Almeida-González, Maira; Henríquez-Hernández, Luis Alberto; Zumbado, Manuel; Boada, Luis D

    2013-10-01

    Analysis of 16 polycyclic aromatic hydrocarbons (PAHs), 20 organochlorine pesticides (OCPs) and 18 polychlorinated biphenyls (PCBs) were performed on eggs from three different production types (conventional, free-run and organic) collected from the markets of the Canary Islands (Spain). Unlike other studies we did not found differences in the content of PCBs or OCPs of eggs in relation to its production type. Median ∑OCPs content was 3.87 ng g⁻¹ fat, being dieldrin, dicofol, hexachlorobenzene, p,p'-DDE and p,p'-DDT the most frequently detected. Median ∑PCBs value was 3.93 ng g⁻¹ fat, with 79.9% of this amount coming from the marker PCBs. Two samples, one free-run and one organic, greatly exceeded the current European Commission (EC) limit of 2.5 pg TEQ(PCDD/F) g⁻¹ lipid, but the rest were well below of this limit. The concentrations of PAHs in conventionally produced eggs were almost 4 times higher than in free-run or organic eggs. Mean dietary intake estimates of the organochlorine contaminants based on consumption of eggs, regardless of the type chosen, is negligible for the Canary Islands' population. However, the median dietary intake estimates of PAHs greatly depend on the type of eggs chosen, being much lower when free-run and organic eggs are consumed. Copyright © 2013 Elsevier Ltd. All rights reserved.

  18. Bicyclic Baird-type aromaticity

    Science.gov (United States)

    Cha, Won-Young; Kim, Taeyeon; Ghosh, Arindam; Zhang, Zhan; Ke, Xian-Sheng; Ali, Rashid; Lynch, Vincent M.; Jung, Jieun; Kim, Woojae; Lee, Sangsu; Fukuzumi, Shunichi; Park, Jung Su; Sessler, Jonathan L.; Chandrashekar, Tavarekere K.; Kim, Dongho

    2017-12-01

    Classic formulations of aromaticity have long been associated with topologically planar conjugated macrocyclic systems. The theoretical possibility of so-called bicycloaromaticity was noted early on. However, it has yet to be demonstrated by experiment in a simple synthetic organic molecule. Conjugated organic systems are attractive for studying the effect of structure on electronic features. This is because, in principle, they can be modified readily through dedicated synthesis. As such, they can provide useful frameworks for testing by experiment with fundamental insights provided by theory. Here we detail the synthesis and characterization of two purely organic non-planar dithienothiophene-bridged [34]octaphyrins that permit access to two different aromatic forms as a function of the oxidation state. In their neutral forms, these congeneric systems contain competing 26 and 34 π-electronic circuits. When subject to two-electron oxidation, electronically mixed [4n+1]/[4n+1] triplet biradical species in the ground state are obtained that display global aromaticity in accord with Baird's rule.

  19. Production of biogenic manganese oxides coupled with methane oxidation in a bioreactor for removing metals from wastewater.

    Science.gov (United States)

    Matsushita, Shuji; Komizo, Daisuke; Cao, Linh Thi Thuy; Aoi, Yoshiteru; Kindaichi, Tomonori; Ozaki, Noriatsu; Imachi, Hiroyuki; Ohashi, Akiyoshi

    2018-03-01

    Biogenic manganese oxide (BioMnO x ) can efficiently adsorb various minor metals. The production of BioMnO x in reactors to remove metals during wastewater treatment processes is a promising biotechnological method. However, it is difficult to preferentially enrich manganese-oxidizing bacteria (MnOB) to produce BioMnO x during wastewater treatment processes. A unique method of cultivating MnOB using methane-oxidizing bacteria (MOB) to produce soluble microbial products is proposed here. MnOB were successfully enriched in a methane-fed reactor containing MOB. BioMnO x production during the wastewater treatment process was confirmed. Long-term continual operation of the reactor allowed simultaneous removal of Mn(II), Co(II), and Ni(II). The Co(II)/Mn(II) and Ni(II)/Mn(II) removal ratios were 53% and 19%, respectively. The degree to which Mn(II) was removed indicated that the enriched MnOB used utilization-associated products and/or biomass-associated products. Microbial community analysis revealed that methanol-oxidizing bacteria belonging to the Hyphomicrobiaceae family played important roles in the oxidation of Mn(II) by using utilization-associated products. Methane-oxidizing bacteria were found to be inhibited by MnO 2 , but the maximum Mn(II) removal rate was 0.49 kg m -3  d -1 . Copyright © 2017 Elsevier Ltd. All rights reserved.

  20. Healthy Dietary Patterns and Oxidative Stress as Measured by Fluorescent Oxidation Products in Nurses’ Health Study

    Directory of Open Access Journals (Sweden)

    Seungyoun Jung

    2016-09-01

    Full Text Available Healthy diets may lower oxidative stress and risk of chronic diseases. However, no previous studies examined associations between diet and fluorescent oxidation products (FlOP, a global marker of oxidative stress. We evaluated associations between healthy eating patterns (Alternative Healthy Eating Index (AHEI, Dietary Approach to Stop Hypertension (DASH, and Alternate Mediterranean Diet (aMED and FlOP, measured at three excitation/emission wavelengths (FlOP_360, FlOP_320, FlOP_400 from 2021 blood samples collected from 1688 women within the Nurses’ Health Study. AHEI, DASH, and aMED scores were significantly positively associated with FlOP_360 and FlOP_320 concentrations (p-trend ≤ 0.04, but not associated with FlOP_400. Among specific food groups that contribute to these diet scores, significantly positive associations were observed with legumes and vegetables for FlOP_360, vegetables and fruits for FlOP_320, and legumes and alcohol for FlOP_400. Inverse associations were observed with nuts, sweets or desserts, and olive oil for FlOP_360, nuts for FlOP_320 and sweets or desserts for FlOP_400 (all p-trend ≤ 0.05. However, FlOP variation due to diet was small compared to overall FlOP variation. In conclusion, AHEI, DASH, and aMED scores were unexpectedly positively, but weakly, associated with FlOP_360 and FlOP_320. However, these findings should be interpreted cautiously as the determinants of FlOP concentrations are not fully understood.

  1. Healthy Dietary Patterns and Oxidative Stress as Measured by Fluorescent Oxidation Products in Nurses' Health Study.

    Science.gov (United States)

    Jung, Seungyoun; Smith-Warner, Stephanie A; Willett, Walter C; Wang, Molin; Wu, Tianying; Jensen, Majken; Hankinson, Susan E; Eliassen, A Heather

    2016-09-21

    Healthy diets may lower oxidative stress and risk of chronic diseases. However, no previous studies examined associations between diet and fluorescent oxidation products (FlOP), a global marker of oxidative stress. We evaluated associations between healthy eating patterns (Alternative Healthy Eating Index (AHEI), Dietary Approach to Stop Hypertension (DASH), and Alternate Mediterranean Diet (aMED)) and FlOP, measured at three excitation/emission wavelengths (FlOP_360, FlOP_320, FlOP_400) from 2021 blood samples collected from 1688 women within the Nurses' Health Study. AHEI, DASH, and aMED scores were significantly positively associated with FlOP_360 and FlOP_320 concentrations ( p -trend ≤ 0.04), but not associated with FlOP_400. Among specific food groups that contribute to these diet scores, significantly positive associations were observed with legumes and vegetables for FlOP_360, vegetables and fruits for FlOP_320, and legumes and alcohol for FlOP_400. Inverse associations were observed with nuts, sweets or desserts, and olive oil for FlOP_360, nuts for FlOP_320 and sweets or desserts for FlOP_400 (all p -trend ≤ 0.05). However, FlOP variation due to diet was small compared to overall FlOP variation. In conclusion, AHEI, DASH, and aMED scores were unexpectedly positively, but weakly, associated with FlOP_360 and FlOP_320. However, these findings should be interpreted cautiously as the determinants of FlOP concentrations are not fully understood.

  2. Nitrous oxide production associated with coastal marine invertebrates

    DEFF Research Database (Denmark)

    Heisterkamp, Ines Maria; Schramm, Andreas; de Beer, Dirk

    2010-01-01

    Several freshwater and terrestrial invertebrate species emit the greenhouse gas nitrous oxide (N2O). The N2O production associated with these animals was ascribed to incomplete denitrification by ingested sediment or soil bacteria. The present study shows that many marine invertebrates also emit N2......O at substantial rates. A total of 19 invertebrate species collected in the German Wadden Sea and in Aarhus Bay, Denmark, and 1 aquacultured shrimp species were tested for N2O emission. Potential N2O emission rates ranged from 0 to 1.354 nmol ind.–1 h–1, with an average rate of 0.320 nmol ind.–1 h–1...... with an experimentally cleaned shell. Thus, the N2O production associated with marine invertebrates is apparently not due to gut denitrification in every species, but may also result from microbial activity on the external surfaces of animals. The high abundance and potential N2O emission rates of many marine...

  3. Durability of solid oxide electrolysis cells for hydrogen production

    Energy Technology Data Exchange (ETDEWEB)

    Hauch, A.; Hoejgaard Jensen, S.; Dalgaard Ebbesen, S.

    2007-05-15

    In the perspective of the increasing interest in renewable energy and hydrogen economy, the reversible solid oxide cells (SOCs) is a promising technology as it has the potential of providing efficient and cost effective hydrogen production by high temperature electrolysis of steam (HTES). Furthermore development of such electrolysis cells can gain from the results obtained within the R and D of SOFCs. For solid oxide electrolysis cells (SOEC) to become interesting from a technological point of view, cells that are reproducible, high performing and long-term stable need to be developed. In this paper we address some of the perspectives of the SOEC technology i.e. issues such as a potential H2 production price as low as 0.71 US dollar/kg H{sub 2} using SOECs for HTES; is there a possible market for the electrolysers? and what R and D steps are needed for the realisation of the SOEC technology? In the experimental part we present electrolysis test results on SOCs that have been optimized for fuel cell operation but applied for HTES. The SOCs are produced on a pre-pilot scale at Risoe National Laboratory. These cells have been shown to have excellent initial electrolysis performance, but the durability of such electrolysis cells are not optimal and examples of results from SOEC tests over several hundreds of hours are given here. The long-term tests have been run at current densities of -0.5 A/cm{sup 2} and -1 A/cm{sup 2}, temperatures of 850 deg. C and 950 deg. C and p(H{sub 2}O)/p(H{sub 2}) of 0.5/0.5 and 0.9/0.1. Long-term degradation rates are shown to be up to 5 times higher for SOECs compared to similar SOFC testing. Furthermore, hydrogen and synthetic fuel production prices are calculated using the experimental results from long-term electrolysis test as input and a short outlook for the future work on SOECs will be given as well. (au)

  4. Conservation and sustainable use of medicinal and aromatic products in North America: Are there really lessons to be learned?

    Science.gov (United States)

    A. L. Hammett; James L. Chamberlain

    2002-01-01

    This paper discusses the legacy of nontimber forest products (NTFPs) and, more specifically, medicinal plant use in North America. It also discusses briefly MAP markets both in North America and throughout the world, and describes the constraints to the sustainable use and development of MAP resources. Lastly, the paper relates some lessons that may be appropriate for...

  5. Gross nitrous oxide production drives net nitrous oxide fluxes across a salt marsh landscape.

    Science.gov (United States)

    Yang, Wendy H; Silver, Whendee L

    2016-06-01

    Sea level rise will change inundation regimes in salt marshes, altering redox dynamics that control nitrification - a potential source of the potent greenhouse gas, nitrous oxide (N2 O) - and denitrification, a major nitrogen (N) loss pathway in coastal ecosystems and both a source and sink of N2 O. Measurements of net N2 O fluxes alone yield little insight into the different effects of redox conditions on N2 O production and consumption. We used in situ measurements of gross N2 O fluxes across a salt marsh elevation gradient to determine how soil N2 O emissions in coastal ecosystems may respond to future sea level rise. Soil redox declined as marsh elevation decreased, with lower soil nitrate and higher ferrous iron in the low marsh compared to the mid and high marshes (P production was highest in the low marsh and lowest in the mid-marsh (P = 0.02), whereas gross N2 O consumption did not differ among marsh zones. Thus, variability in gross N2 O production rates drove the differences in net N2 O flux among marsh zones. Our results suggest that future studies should focus on elucidating controls on the processes producing, rather than consuming, N2 O in salt marshes to improve our predictions of changes in net N2 O fluxes caused by future sea level rise. © 2015 John Wiley & Sons Ltd.

  6. Relative rates of nitric oxide and nitrous oxide production by nitrifiers, denitrifiers, and nitrate respirers

    Science.gov (United States)

    Anderson, I. C.; Levine, J. S.

    1986-01-01

    An account is given of the atmospheric chemical and photochemical effects of biogenic nitric and nitrous oxide emissions. The magnitude of the biogenic emission of NO is noted to remain uncertain. Possible soil sources of NO and N2O encompass nitrification by autotropic and heterotropic nitrifiers, denitrification by nitrifiers and denitrifiers, nitrate respiration by fermenters, and chemodenitrification. Oxygen availability is the primary determinant of these organisms' relative rates of activity. The characteristics of this major influence are presently investigated in light of the effect of oxygen partial pressure on NO and N2O production by a wide variety of common soil-nitrifying, denitrifying, and nitrate-respiring bacteria under laboratory conditions. The results obtained indicate that aerobic soils are primary sources only when there is sufficient moisture to furnish anaerobic microsites for denitrification.

  7. Volatile profile, lipid oxidation and protein oxidation of irradiated ready-to-eat cured turkey meat products

    International Nuclear Information System (INIS)

    Feng, Xi; Ahn, Dong Uk

    2016-01-01

    Irradiation had little effects on the thiobarbituric acid reactive substances (TBARS) values in ready-to-eat (RTE) turkey meat products, while it increased protein oxidation at 4.5 kGy. The volatile profile analyses indicated that the amount of sulfur compounds increased linearly as doses increased in RTE turkey meat products. By correlation analysis, a positive correlation was found between benzene/ benzene derivatives and alcohols with lipid oxidation, while aldehydes, ketones and alkane, alkenes and alkynes were positively correlated with protein oxidation. Principle component analysis showed that irradiated meat samples can be discriminated by two categories of volatile compounds: Strecker degradation products and radiolytic degradation products. The cluster analysis of volatile data demonstrated that low-dose irradiation had minor effects on the volatile profile of turkey sausages (<1.5 kGy). However, as the doses increased, the differences between the irradiated and non-irradiated cured turkey products became significant. - Highlights: • Irradiation had little effects on lipid oxidation of ready-to-eat cured turkey. • 4.5 kGy irradiation increased protein oxidation. • Irradiated samples were isolated due to Strecker/radiolytic degradation products. • 1.5 kGy irradiation had limited effects on the volatile profile of turkey sausages. • Dimethyl disulfide can be used as a potential marker for irradiated meat products.

  8. Strategies to mitigate nitrous oxide emissions from herbivore production systems.

    Science.gov (United States)

    Schils, R L M; Eriksen, J; Ledgard, S F; Vellinga, Th V; Kuikman, P J; Luo, J; Petersen, S O; Velthof, G L

    2013-03-01

    Herbivores are a significant source of nitrous oxide (N(2)O) emissions. They account for a large share of manure-related N(2)O emissions, as well as soil-related N(2)O emissions through the use of grazing land, and land for feed and forage production. It is widely acknowledged that mitigation measures are necessary to avoid an increase in N(2)O emissions while meeting the growing global food demand. The production and emissions of N(2)O are closely linked to the efficiency of nitrogen (N) transfer between the major components of a livestock system, that is, animal, manure, soil and crop. Therefore, mitigation options in this paper have been structured along these N pathways. Mitigation technologies involving diet-based intervention include lowering the CP content or increasing the condensed tannin content of the diet. Animal-related mitigation options also include breeding for improved N conversion and high animal productivity. The main soil-based mitigation measures include efficient use of fertilizer and manure, including the use of nitrification inhibitors. In pasture-based systems with animal housing facilities, reducing grazing time is an effective option to reduce N(2)O losses. Crop-based options comprise breeding efforts for increased N-use efficiency and the use of pastures with N(2)-fixing clover. It is important to recognize that all N(2)O mitigation options affect the N and carbon cycles of livestock systems. Therefore, care should be taken that reductions in N(2)O emissions are not offset by unwanted increases in ammonia, methane or carbon dioxide emissions. Despite the abundant availability of mitigation options, implementation in practice is still lagging. Actual implementation will only follow after increased awareness among farmers and greenhouse gases targeted policies. So far, reductions in N(2)O emissions that have been achieved are mostly a positive side effect of other N-targeted policies.

  9. Poly-3-hydroxybutyrate (PHB) production from alkylphenols, mono and poly-aromatic hydrocarbons using Bacillus sp. CYR1: A new strategy for wealth from waste.

    Science.gov (United States)

    Venkateswar Reddy, M; Mawatari, Yasuteru; Yajima, Yuka; Seki, Chigusa; Hoshino, Tamotsu; Chang, Young-Cheol

    2015-09-01

    In the present study five different types of alkylphenols, each of the two different types of mono and poly-aromatic hydrocarbons were selected for degradation, and conversion into poly-3-hydroxybutyrate (PHB) using the Bacillus sp. CYR1. Strain CYR1 showed growth with various toxic organic compounds. Degradation pattern of all the organic compounds at 100 mg/l concentration with or without addition of tween-80 were analyzed using high pressure liquid chromatography (HPLC). Strain CYR1 showed good removal of compounds in the presence of tween-80 within 3 days, but it took 6 days without addition of tween-80. Strain CYR1 showed highest PHB production with phenol (51 ± 5%), naphthalene (42 ± 4%), 4-chlorophenol (32 ± 3%) and 4-nonylphenol (29 ± 3%). The functional groups, structure, and thermal properties of the produced PHB were analyzed. These results denoted that the strain Bacillus sp. CYR1 can be used for conversion of different toxic compounds persistent in wastewaters into useable biological polyesters. Copyright © 2015 Elsevier Ltd. All rights reserved.

  10. Tungsten and molybdenum with oxide dispersion, production and properties

    International Nuclear Information System (INIS)

    Haerdtle, S.; Schmidberger, R.

    1989-01-01

    By the reaction spray process metal powders with dispersed metal oxides can be produced in one step. The systems investigated here are tungsten and molybdenum with 0,5% resp. 5% La 2 O 3 , Y 2 O 3 and ZrO 2 . The oxides with diameters below 0,5μm are finely dispersed within the metal powder particles. The sinterability of the powders depends on the oxide content. Maximum density at an oxide content of 0,5% is about 96% at a sintering temperature of 1600 0 C. The type of oxide influences the densification versus temperature but not the final density. 5 refs., 11 figs. (Author)

  11. Global modeling of secondary organic aerosol formation from aromatic hydrocarbons: high- vs. low-yield pathways

    Directory of Open Access Journals (Sweden)

    D. K. Henze

    2008-05-01

    Full Text Available Formation of SOA from the aromatic species toluene, xylene, and, for the first time, benzene, is added to a global chemical transport model. A simple mechanism is presented that accounts for competition between low and high-yield pathways of SOA formation, wherein secondary gas-phase products react further with either nitric oxide (NO or hydroperoxy radical (HO2 to yield semi- or non-volatile products, respectively. Aromatic species yield more SOA when they react with OH in regions where the [NO]/[HO2] ratios are lower. The SOA yield thus depends upon the distribution of aromatic emissions, with biomass burning emissions being in areas with lower [NO]/[HO2] ratios, and the reactivity of the aromatic with respect to OH, as a lower initial reactivity allows transport away from industrial source regions, where [NO]/[HO2] ratios are higher, to more remote regions, where this ratio is lower and, hence, the ultimate yield of SOA is higher. As a result, benzene is estimated to be the most important aromatic species with regards to global formation of SOA, with a total production nearly equal that of toluene and xylene combined. Global production of SOA from aromatic sources via the mechanisms identified here is estimated at 3.5 Tg/yr, resulting in a global burden of 0.08 Tg, twice as large as previous estimates. The contribution of these largely anthropogenic sources to global SOA is still small relative to biogenic sources, which are estimated to comprise 90% of the global SOA burden, about half of which comes from isoprene. Uncertainty in these estimates owing to factors ranging from the atmospheric relevance of chamber conditions to model deficiencies result in an estimated range of SOA production from aromatics of 2–12 Tg/yr. Though this uncertainty range affords a significant anthropogenic contribution to global SOA, it is evident from comparisons to recent observations that additional pathways for

  12. The direct aromatization of methane

    Energy Technology Data Exchange (ETDEWEB)

    Marcelin, G.; Oukaci, R.; Migone, R.A.; Kazi, A.M. [Altamira Instruments, Pittsburgh, PA (United States)

    1995-12-31

    The thermal decomposition of methane shows significant potential as a process for the production of higher unsaturated and aromatic hydrocarbons when the extent of the reaction is limited. Thermodynamic calculations have shown that when the reaction is limited to the formation of C{sub 2} to C{sub 10} products, yields of aromatics can exceed 40% at temperatures of 1200{degrees}C. Preliminary experiments have shown that when the reaction is limited to the formation of C{sub 2} to C{sub 10} products, yields of aromatics can exceed 40% at temperatures of 1200{degrees}C. Preliminary experiments have shown that cooling the product and reacting gases as the reaction proceeds can significantly reduce or eliminate the formation of solid carbon and heavier (C{sub 10+}) materials. Much work remains to be done in optimizing the quenching process and this is one of the goals of this program. Means to lower the temperature of the reaction are being studied as this result in a more feasible commercial process due to savings realized in energy and material of construction costs. The use of free-radical generators and catalysts will be investigated as a means of lowering the reaction temperature thus allowing faster quenching. It is highly likely that such studies will lead to a successful direct methane to higher hydrocarbon process.

  13. Method of manufacturing gadolinium oxide-incorporated nuclear fuel sintering products

    International Nuclear Information System (INIS)

    Komono, Akira; Seki, Makoto; Omori, Sadayuki.

    1987-01-01

    Purpose: To manufacture nuclear fuel sintering products excellent in burning property and mechanical property. Constitution: In the manufacturing step for nuclear fuel sintering products, specific metal oxides are added for promoting the growth of crystal grains in the sintering. Those metal oxides melted at a temperature lower than the sintering temperature of a mixture of nuclear fuel oxide powder and oxide power, or those metal oxides causing eutectic reaction are used as the metal oxide. Particularly, those compounds having oxygen atom - metal atom ratio (O/M) of not less than 2 are preferably used. As such metal oxides usable herein transition metal oxides, e.g., Nb 2 O 5 , TiO 2 , MoO 3 and WO 3 are preferred, with Nb 2 O 3 and TiO 2 being preferred particularly. (Seki, T.)

  14. Occurrence and exposure to polycyclic aromatic hydrocarbons in kindling-free-charcoal grilled meat products in Taiwan.

    Science.gov (United States)

    Kao, Tsai Hua; Chen, Shaun; Huang, Chun Wei; Chen, Chia Ju; Chen, Bing Huei

    2014-09-01

    This study aimed to determine the contents of 16 PAHs in kindling-free-charcoal grilled meat and seafood products by GC-MS coupled with a QuEChERS method, and estimate the potential risk associated with consumption of those products in Taiwan. Results showed that the total PAHs contents ranged from 6.3±0.9 to 238.8±8.3 ng/g in poultry meat, 0.1±0.0-547.5±12.2 ng/g in red meat, and 6.6±1.4-249.7±6.4 ng/g in seafood products. Among various PAHs, the highly carcinogenic benzo[a]pyrene was detected in chicken breast grilled at 84°C (30 min), chicken heart at 100°C (26 min), chicken drumstick at 74°C (20 min), duck drumstick at 85°C (40 min), and lamb steak at 88°C (12 min), with its level amounting to 1.3±0.0, 2.4±0.1, 4.0±1.3, 3.1±0.0, and 5.8±0.5 ng/g, respectively. The generation of PAHs was associated with grilling time, temperature and fat content. Risk assessment of dietary exposure to PAHs revealed toxicity equivalent to range from ND - 6.174±0.505 μg/g and margin of exposure was >10,000, which agreed with the EFSA's definition of low public health concern. The lifelong average daily PAHs intake was higher for adults than for elderly people in Taiwan, however, consumption of kindling-free-charcoal grilled meat should not be a public health concern based on cancer risk potency. Copyright © 2014 Elsevier Ltd. All rights reserved.

  15. Hydrogen Production via Steam Reforming of Ethyl Alcohol over Palladium/Indium Oxide Catalyst

    Directory of Open Access Journals (Sweden)

    Tetsuo Umegaki

    2009-01-01

    Full Text Available We report the synergetic effect between palladium and indium oxide on hydrogen production in the steam reforming reaction of ethyl alcohol. The palladium/indium oxide catalyst shows higher hydrogen production rate than indium oxide and palladium. Palladium/indium oxide affords ketonization of ethyl alcohol with negligible by-product carbon monoxide, while indium oxide mainly affords dehydration of ethyl alcohol, and palladium affords decomposition of ethyl alcohol with large amount of by-product carbon monoxide. The catalytic feature of palladium/indium oxide can be ascribed to the formation of palladium-indium intermetallic component during the reaction as confirmed by X-ray diffraction and X-ray photoelectron spectroscopic measurements.

  16. Oxydation des huiles de bases minérales d'origine pétrolière. Relation entre leur composition chimique, l'épaississement et la composition de leur produits de dégradation Oxidation of Mineral Base Stocks of Petroleum Origin. Relationship Between Chemical Composition, Thickening and Oxidized Degradation Products

    Directory of Open Access Journals (Sweden)

    Faure D.

    2006-11-01

    composition (Table 1. By tests during which the amount of oxygen consumed is controled continuously (IFP OXYTEST, modified TFOUT and by differential scanning calorimetry analysis (DSC, we have investigated the behavior of these different base stocks with regard to oxidation. Mineral base stocks with high contents of aromatics compounds and sulfur are partially and naturally protected against oxidation. The same is not true for hydroisomerized base stocks, which contain no natural inhibitor and so are very easily oxidized (Fig. 2. However, all such oils become oxidized quickly as soon as they are subjected to high temperatures in the presence of air or oxygen and an oxidation catalyzing metal (Fig. 3. In the presence of soluble iron salts used as catalysts, we havefound that, to be partially selfprotected against oxidation, a base stock must contain a minimum of aromatic carbons (CA > ou = 5 % and sulfur (S > ou = 0. 5 %, with this sulfur generally being linked to aromatic compounds in the thiophenic form (Fig. 4. We will also show that, whereas the oxidation of a base stock issuing from refining products causes an increase in the viscosity of this base stock, this increase is linked directly to the amount of oxygen consumed and depends solely on this amount, no matter what the antioxidant additive may be or the amount of catalyst present. For a given amount of oxygen consumed, the variation in viscosity is independent of the temperature and duration of oxidation as well as of the concentration and choice of the antioxidant (Table 3, Figs. 5 and 6. The antioxidant properties of natural sulfur-containing aromatic compounds have been demonstrated by incorporating them in polyalphaolefin PA06 after they have been extracted from MO and MDN oils and by studying the oxidation stability of the mixtures thus obtained by thin-layer oxidation by DSC (Table 5. Whereas PA06 has no natural resistance to oxidation, the addition of aromatic compounds coming from MO and MDN oils give this

  17. Cu-catalyzed C(sp³)-H bond activation reaction for direct preparation of cycloallyl esters from cycloalkanes and aromatic aldehydes.

    Science.gov (United States)

    Zhao, Jincan; Fang, Hong; Han, Jianlin; Pan, Yi

    2014-05-02

    Cu-catalyzed dehydrogenation-olefination and esterification of C(sp(3))-H bonds of cycloalkanes with TBHP as an oxidant has been developed. The reaction involves four C-H bond activations and gives cycloallyl ester products directly from cycloalkanes and aromatic aldehydes.

  18. ARIES Oxide Production Program Assessment of Risk to Long-term Sustainable Production Rate

    Energy Technology Data Exchange (ETDEWEB)

    Whitworth, Julia [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Lloyd, Jane Alexandria [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Majors, Harry W. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2017-05-04

    This report describes an assessment of risks and the development of a risk watch list for the ARIES Oxide Production Program conducted in the Plutonium Facility at LANL. The watch list is an active list of potential risks and opportunities that the management team periodically considers to maximize the likelihood of program success. The initial assessments were made in FY 16. The initial watch list was reviewed in September 2016. The initial report was not issued. Revision 1 has been developed based on management review of the original watch list and includes changes that occurred during FY-16.

  19. Elastin aging and lipid oxidation products in human aorta

    Directory of Open Access Journals (Sweden)

    Kamelija Zarkovic

    2015-04-01

    Full Text Available Vascular aging is associated with structural and functional modifications of the arteries, and by an increase in arterial wall thickening in the intima and the media, mainly resulting from structural modifications of the extracellular matrix (ECM components. Among the factors known to accumulate with aging, advanced lipid peroxidation end products (ALEs are a hallmark of oxidative stress-associated diseases such as atherosclerosis. Aldehydes generated from the peroxidation of polyunsaturated fatty acids (PUFA, (4-hydroxynonenal, malondialdehyde, acrolein, form adducts on cellular proteins, leading to a progressive protein dysfunction with consequences in the pathophysiology of vascular aging. The contribution of these aldehydes to ECM modification is not known. This study was carried out to investigate whether aldehyde-adducts are detected in the intima and media in human aorta, whether their level is increased in vascular aging, and whether elastin fibers are a target of aldehyde-adduct formation. Immunohistological and confocal immunofluorescence studies indicate that 4-HNE-histidine-adducts accumulate in an age-related manner in the intima, media and adventitia layers of human aortas, and are mainly expressed in smooth muscle cells. In contrast, even if the structure of elastin fiber is strongly altered in the aged vessels, our results show that elastin is not or very poorly modified by 4-HNE. These data indicate a complex role for lipid peroxidation and in particular for 4-HNE in elastin homeostasis, in the vascular wall remodeling during aging and atherosclerosis development.

  20. Degradation of the azo dye Acid Red 1 by anodic oxidation and indirect electrochemical processes based on Fenton's reaction chemistry. Relationship between decolorization, mineralization and products

    International Nuclear Information System (INIS)

    Florenza, Xavier; Solano, Aline Maria Sales; Centellas, Francesc; Martínez-Huitle, Carlos Alberto

    2014-01-01

    Highlights: • Degradation of Acid Red 1 by anodic oxidation, electro-Fenton and photoelectro-Fenton • Quicker and similar decolorization by electro-Fenton and photoelectro-Fenton due to oxidation with ● OH in the bulk • Almost total mineralization by photoelectro-Fenton with Pt or BDD due to fast photolysis of products by UVA light • Detection of 11 aromatic products, 15 hydroxylated compounds, 13 desulfonated derivatives and 7 carboxylic acids • Release of NH 4 + , NO 3 − and SO 4 2− ions, and generation of persistent N-products of low molecular mass - Abstract: Solutions of 236 mg dm −3 Acid Red 1 (AR1), an azo dye widely used in textile dying industries, at pH 3.0 have been comparatively treated by anodic oxidation with electrogenerated H 2 O 2 (AO-H 2 O 2 ), electro-Fenton (EF) and photoelectro-Fenton (PEF) at constant current density (j). Assays were performed with a stirred tank reactor equipped with a Pt or boron-doped diamond (BDD) anode and an air-diffusion cathode for H 2 O 2 generation from O 2 reduction. The main oxidizing agents were hydroxyl radicals produced at the anode from water oxidation in all methods and in the bulk from Fenton's reaction between generated H 2 O 2 and 0.5 mmol dm −3 Fe 2+ in EF and PEF. For each anode, higher oxidation power was found in the sequence AO-H 2 O 2 < EF < PEF. The oxidation ability of the BDD anode was always superior to that of Pt. Faster and similar decolorization efficiency was achieved in EF and PEF owing to the quicker destruction of aromatics with hydroxyl radicals produced in the bulk. The PEF process with BDD was the most potent method yielding almost total mineralization due to the additional rapid photolysis of recalcitrant intermediates like Fe(III)-carboxylate complexes under UVA irradiation. The increase in j always enhanced the decolorization and mineralization processes because of the greater production of hydroxyl radicals, but decreases the mineralization current efficiency

  1. Reduction of Aromatic and Heterocyclic Aromatic N-Hydroxylamines by Human Cytochrome P450 2S1

    Science.gov (United States)

    Wang, Kai; Guengerich, F. Peter

    2013-01-01

    Many aromatic amines and heterocyclic aromatic amines (HAAs) are known carcinogens for animals and there is also strong evidence for some in human cancer. The activation of these compounds, including some arylamine drugs, involves N-hydroxylation, usually by cytochrome P450 enzymes (P450) in Family 1 (1A2, 1A1, and 1B1). We previously demonstrated that the bioactivation product of the anti-cancer agent 2-(4-amino-3-methylphenyl)-5-fluorobenzothiazole (5F 203), an N-hydroxylamine, can be reduced by P450 2S1 to its amine precursor under anaerobic conditions and, to a lesser extent, under aerobic conditions (Wang, K., and Guengerich, F. P. (2012) Chem. Res. Toxicol. 25, 1740–1751). In the present study, we tested the hypothesis that P450 2S1 is involved in the reductive biotransformation of known carcinogenic aromatic amines and HAAs. The N-hydroxylamines of 4-aminobiphenyl (4-ABP), 2-naphthylamine (2-NA), and 2-aminofluorene (2-AF) were synthesized and found to be reduced by P450 2S1 under both anaerobic and aerobic conditions. The formation of amines due to P450 2S1 reduction also occurred under aerobic conditions but was less apparent because the competitive disproportionation reactions (of the N-hydroxylamines) also yielded amines. Further, some nitroso and nitro derivatives of the arylamines could also be reduced by P450 2S1. None of the amines tested were oxidized by P450 2S1. These results suggest that P450 2S1 may be involved in the reductive detoxication of several of the activated products of carcinogenic aromatic amines and HAAs. PMID:23682735

  2. Analysis of microbial populations, denitrification, and nitrous oxide production in riparian buffers

    Science.gov (United States)

    Riparian buffers are used extensively to protect water bodies from nonpoint source nitrogen pollution. However there is relatively little information on the impact of these buffers on production of nitrous oxide (N2O). In this study, we assessed nitrous oxide production in riparian buffers of the so...

  3. Methods to assess secondary volatile lipid oxidation products in complex food matrices

    DEFF Research Database (Denmark)

    Jacobsen, Charlotte; Yesiltas, Betül

    A range of different methods are available to determine secondary volatile lipid oxidation products. These methods include e.g. spectrophotometric determination of anisidine values and TBARS as well as GC based methods for determination of specific volatile oxidation products such as pentanal...... headspace methods on the same food matrices will be presented....

  4. STIMULATION OF OXIDANT PRODUCTION IN ALVEOLAR MACROPHAGES BY POLLUTANT AND LATEX PARTICLES

    Science.gov (United States)

    Air pollutant dusts as well as chemically defined particles were examined for their activating effect on oxidant production (O2- and H2O2) in guinea pig alveolar macrophages (AM). Oxidant production was measured as chemiluminescence of albumin-bound luminol. All particles examine...

  5. Characterization of oxidation end product of plasma albumin 'in vivo'.

    Science.gov (United States)

    Musante, Luca; Bruschi, Maurizio; Candiano, Giovanni; Petretto, Andrea; Dimasi, Nazzareno; Del Boccio, Piero; Urbani, Andrea; Rialdi, Giovanni; Ghiggeri, Gian Marco

    2006-10-20

    Anti-oxidants are paradoxically much lower in plasma than inside cells even blood is comparably exposed to the oxidative stress. 'In vitro' models suggest a critical role of albumin as substitutive anti-oxidant in plasma but no proof for this role is available 'in vivo.' Herein, we demonstrate by LC/MS/MS that plasma albumin undergoes massive oxidation in primary nephrotic syndrome, involving stable sulphonation SO3- of the free SH of Cys 34 with +48Da increase in exact mass of the protein (ESI-MS) and formation of a fast moving isoform in the pH range between 5 and 7. Physical-chemical experiments with DSC and fluorescence spectra indicate a thermal stabilization of the structure upon oxidation. This is the first demonstration of massive oxidation of albumin 'in vivo' that reflects a functional role of the protein. Free radicals should be implicated in the pathogenesis of proteinuria in human FSGS.

  6. [Effects of metal-catalyzed oxidation on the formation of advanced oxidation protein products].

    Science.gov (United States)

    Li, Li; Peng, Ai; Zhu, Kai-Yuan; Yu, Hong; Ll, Xin-Hua; Li, Chang-Bin

    2008-03-11

    To explore the relationship between metal-catalyzed oxidation (MCO) and the formation of advanced oxidation protein products (AOPPs). Specimens of human serum albumin (HSA) and pooled plasma were collected from 3 healthy volunteers and 4 uremia patients were divided into 3 groups: Group A incubated with copper sulfate solution of the concentrations of 0, 0.2, or 0.5 mmol/L, Group B, incubated with hydrogen peroxide 2 mmol/L, and Group C, incubated with copper sulfate 0.2 or 0.5 mmol/L plus hydrogen peroxide 2 mmol/L. 30 min and 24 h later the AOPP level was determined by ultraviolet visible spectrophotometry. High-performance liquid chromatography (HPLC) was used to observe the fragmentation effect on plasma proteins. Ninhydrin method was used to examine the protein fragments. The scavenging capacity of hydroxyl radical by macromolecules was measured so as to estimate the extent of damage for proteins induced by MCO. (1) The AOPP level of the HSA and plasma specimens of the uremia patients increased along with the increase of cupric ion concentration in a dose-dependent manner, especially in the presence of hydrogen peroxide (P < 0.05). (2) Aggregation of proteins was almost negligible in all groups, however, HPLC showed that cupric ion with or without hydrogen peroxide increased the fragments in the HAS specimens (with a relative molecular mass of 5000) and uremia patients' plasma proteins (with the molecular mass 7000). (3) The plasma AOPP level of the healthy volunteers was 68.2 micromol/L +/- 2.4 micromol/L, significantly lower than that of the uremia patients (158.5 micromol/L +/- 8.2 micromol/L). (4) The scavenging ability to clear hydroxyl radical by plasma proteins of the healthy volunteers was 1.38 -9.03 times as higher than that of the uremia patients. MCO contributes to the formation of AOPPs mainly through its fragmentation effect to proteins.

  7. Regularities of synthesis and mechanism of polycondensation of aromatic amines

    International Nuclear Information System (INIS)

    Matnishyan, Hagob

    2002-01-01

    Full text.Aniline polymers and its derivatives are widely used in modern electronics, electrical engineering and manufacturing of various appliances. They are used for production of electrical power sources, probes and sensors, composite materials absorbing high frequency radiations, anticorrosion coatings, nonlinear optical devices-such as lasers, cathode ray tubes, photodiodes etc. Such a wide usage of aromatic amine polymers brings up new demands to their structure and properties, which is dependent on conditions of synthesis and forming of the hard phase. The presented article describes regularities and mechanisms of oxidative polycondensation of aromatic amines. Several types of polymers have been synthesized by chemical and electrochemical oxidation of aniline and its chlor-, brom-, iodo-, nitro-, p-substituted derivatives; diphenylamine, benzidine and phenylenediamines in nonwater media. On the basis of kinetic and electrochemical studies and literature analysis we suggested a mechanism of polycondensation of aromatic amines. According to it, oxidation of amines starts with the electron transfer with cation-radical formation on the first stage, which stabilizes in acid environments due to complex formation with initial amine. Dimer formation and further growth of chain takes place upon another electron transfer from formed complex, which results in forming of macromolecules. We also suggested a scheme for obtaining of structures defect in media assisting in deprotonizing of cation radicals and formation of arylamine radical centers. Those processes lead to formation of azo- and diphenyl fragments in the main chain of the polymer and predetermine the possibility of chain disruption. We also considered reactions leading to formation of branched polymers and cyclic structures, such as phenazine in particular. The peculiarity of electrochemical process lies in regulation of concentration of active centres on the positive electrode surface

  8. Aromater i drikkevand

    DEFF Research Database (Denmark)

    Nyeland, B. A.; Hansen, A. B.

    DMU har den 10. Juni 1997 afholdt en præstationsprøvning: Aromater i drikkevand. Der deltog 21 laboratorier i præstationsprøvningen. Prøvningen omfattede 6 vandige prøver og 6 ampuller indeholdende 6 aromater. Laboratorierne spikede de tilsendte vandprøver med indholdet fra ampullerne...

  9. Generalized cytochrome P450-mediated oxidation and oxygenation reactions in aromatic substrates with activated N-H, O-H, C-H, or S-H substituents

    NARCIS (Netherlands)

    Koymans, L.; Donné-Op den Kelder, G M; te Koppele, J.M.; Vermeulen, N P

    1. The general mechanism of metabolic oxidation of substrates by cytochromes P450 (P450s) appears to consist of sequential one-electron oxidation steps rather than of a single concerted transfer of activated oxygen species from P450 to substrates. 2. In case of the acetanilides paracetamol (PAR),

  10. Low nitrous oxide production in intermittent-feed high performance nitritating reactors

    DEFF Research Database (Denmark)

    Su, Qingxian; Jensen, Malene M.; Smets, Barth F.

    Nitrous oxide (N2O) production from autotrophic nitrogen removal processes, especially nitritating systems, is of growing concern. N2O dynamics were characterized and N2O production factors were quantified in two lab-scale intermittent-feed nitritating SBRs. 93 ± 14% of the oxidized ammonium...... was converted to nitrite, with the average total net N2O production of 2.1 ± 0.7% of the ammonium oxidized. Operation with intermittent feeding appears an effective optimization approach to mitigate N2O emissions from nitritating systems. Net N2O production rates transiently increased with a rise in pH after...

  11. Detection of HOCl-mediated protein oxidation products in the extracellular matrix of human atherosclerotic plaques

    DEFF Research Database (Denmark)

    Woods, Alan A; Linton, Stuart M; Davies, Michael Jonathan

    2003-01-01

    Oxidation is believed to play a role in atherosclerosis. Oxidized lipids, sterols and proteins have been detected in early, intermediate and advanced human lesions at elevated levels. The spectrum of oxidized side-chain products detected on proteins from homogenates of advanced human lesions has...... been interpreted in terms of the occurrence of two oxidative mechanisms, one involving oxygen-derived radicals catalysed by trace transition metal ions, and a second involving chlorinating species (HOCl or Cl2), generated by the haem enzyme myeloperoxidase (MPO). As MPO is released extracellularly...... for 83-96% of the total oxidized protein side-chain products detected in these plaques. Oxidation of matrix components extracted from healthy artery tissue, and model proteins, with reagent HOCl is shown to give rise to a similar pattern of products to those detected in advanced human lesions...

  12. Elastin aging and lipid oxidation products in human aorta.

    Science.gov (United States)

    Zarkovic, Kamelija; Larroque-Cardoso, Pauline; Pucelle, Mélanie; Salvayre, Robert; Waeg, Georg; Nègre-Salvayre, Anne; Zarkovic, Neven

    2015-01-01

    Vascular aging is associated with structural and functional modifications of the arteries, and by an increase in arterial wall thickening in the intima and the media, mainly resulting from structural modifications of the extracellular matrix (ECM) components. Among the factors known to accumulate with aging, advanced lipid peroxidation end products (ALEs) are a hallmark of oxidative stress-associated diseases such as atherosclerosis. Aldehydes generated from the peroxidation of polyunsaturated fatty acids (PUFA), (4-hydroxynonenal, malondialdehyde, acrolein), form adducts on cellular proteins, leading to a progressive protein dysfunction with consequences in the pathophysiology of vascular aging. The contribution of these aldehydes to ECM modification is not known. This study was carried out to investigate whether aldehyde-adducts are detected in the intima and media in human aorta, whether their level is increased in vascular aging, and whether elastin fibers are a target of aldehyde-adduct formation. Immunohistological and confocal immunofluorescence studies indicate that 4-HNE-histidine-adducts accumulate in an age-related manner in the intima, media and adventitia layers of human aortas, and are mainly expressed in smooth muscle cells. In contrast, even if the structure of elastin fiber is strongly altered in the aged vessels, our results show that elastin is not or very poorly modified by 4-HNE. These data indicate a complex role for lipid peroxidation and in particular for 4-HNE in elastin homeostasis, in the vascular wall remodeling during aging and atherosclerosis development. Copyright © 2015 The Authors. Published by Elsevier B.V. All rights reserved.

  13. Measurements of nitrous oxide emissions from vegetable production in China

    Science.gov (United States)

    Xiong, Zhengqin; Xie, Yingxin; Xing, Guangxi; Zhu, Zhaoliang; Butenhoff, Chris

    Nitrous oxide (N 2O) emissions resulting from Chinese vegetable production were measured. A site in suburban Nanjing (East coast; Jiangsu Province) was monitored from November 2001 to January 2003, in which five consecutive vegetable crops were sown. The crops consisted of radish, baby bok choy, lettuce, second planting of baby bok choy, and finally celery. Results suggested that N 2O emission events occur in pulses. The average N 2O-N flux for all five crops was 148±9 μg N m -2 h -1 and the average emission rate was 12±0.7 kg N ha -1. The average seasonal emission fluxes ranged from 37 μg N m -2 h -1 in the radish plot to 300 μg N m -2 h -1 in the celery plot. The celery field produced the greatest cumulative emission of 5.8 kg N ha -1 while the baby bok choy field had the lowest rate of 0.96-1.0 kg N ha -1. In total, 0.73% of applied fertilizer N was emitted as N 2O-N as a whole. The lettuce field had the largest emission factor of 2.2%. Results indicate that emissions from vegetable field are a potential source of national N 2O inventory. Temporal variation is much greater than spatial variation and the corresponding CV averaged 115% and 22%, respectively. Under the same total sampling quantity, increasing sampling frequency is more important than increasing spatial replicates.

  14. Amorphous semiconducting and conducting transparent metal oxide thin films and production thereof

    Science.gov (United States)

    Perkins, John; Van Hest, Marinus Franciscus Antonius Maria; Ginley, David; Taylor, Matthew; Neuman, George A.; Luten, Henry A.; Forgette, Jeffrey A.; Anderson, John S.

    2010-07-13

    Metal oxide thin films and production thereof are disclosed. An exemplary method of producing a metal oxide thin film may comprise introducing at least two metallic elements and oxygen into a process chamber to form a metal oxide. The method may also comprise depositing the metal oxide on a substrate in the process chamber. The method may also comprise simultaneously controlling a ratio of the at least two metallic elements and a stoichiometry of the oxygen during deposition. Exemplary amorphous metal oxide thin films produced according to the methods herein may exhibit highly transparent properties, highly conductive properties, and/or other opto-electronic properties.

  15. Kinetics, Mechanism, and Secondary Organic Aerosol Yield of Aqueous Phase Photo-oxidation of α-Pinene Oxidation Products.

    Science.gov (United States)

    Aljawhary, Dana; Zhao, Ran; Lee, Alex K Y; Wang, Chen; Abbatt, Jonathan P D

    2016-03-10

    Formation of secondary organic aerosol (SOA) involves atmospheric oxidation of volatile organic compounds (VOCs), the majority of which are emitted from biogenic sources. Oxidation can occur not only in the gas-phase but also in atmospheric aqueous phases such as cloudwater and aerosol liquid water. This study explores for the first time the aqueous-phase OH oxidation chemistry of oxidation products of α-pinene, a major biogenic VOC species emitted to the atmosphere. The kinetics, reaction mechanisms, and formation of SOA compounds in the aqueous phase of two model compounds, cis-pinonic acid (PIN) and tricarballylic acid (TCA), were investigated in the laboratory; TCA was used as a surrogate for 3-methyl-1,2,3-butanetricarboxylic acid (MBTCA), a known α-pinene oxidation product. Aerosol time-of-flight chemical ionization mass spectrometry (Aerosol-ToF-CIMS) was used to follow the kinetics and reaction mechanisms at the molecular level. Room-temperature second-order rate constants of PIN and TCA were determined to be 3.3 (± 0.5) × 10(9) and 3.1 (± 0.2) × 10(8) M(-1) s(-1), respectively, from which were estimated their condensed-phase atmospheric lifetimes. Aerosol-ToF-CIMS detected a large number of products leading to detailed reaction mechanisms for PIN and MBTCA. By monitoring the particle size distribution after drying, the amount of SOA material remaining in the particle phase was determined. An aqueous SOA yield of 40 to 60% was determined for PIN OH oxidation. Although recent laboratory studies have focused primarily on aqueous-phase processing of isoprene-related compounds, we demonstrate that aqueous formation of SOA materials also occurs from monoterpene oxidation products, thus representing an additional source of biogenically driven aerosol formation.

  16. Microbial production of nitrous oxide and nitric oxide in boreal peatlands

    Energy Technology Data Exchange (ETDEWEB)

    Regina, K.

    1998-12-31

    Soils are an important source of nitrous oxide (N{sub 2}O) and nitric oxide (NO). N{sub 2}O is a greenhouse gas participating in both warming of the climate and the destruction of ozone, and NO is active in tropospheric chemistry. The fluxes and formation mechanisms of these gases in boreal Finnish peatlands were studied by both laboratory and field techniques. Special attention was paid to factors regulating their production, e.g. height of the water table, pH, temperature, nutrient level and nitrification activity. Both N{sub 2}O and NO fluxes were detected in the peatlands, some of which were sources of these trace gases and some sinks. The flux rates of N{sub 2}O ranged from negative values to several milligrammes per square metre per day. Natural peatlands were the lowest sources of N{sub 2}O, often showing negative fluxes, whereas sites drained for forestry some decades ago had markedly higher fluxes. A site drained for agriculture (grassland) was the highest source found. NO fluxes were observed on the two drained sites studied, a forested fen and the same field of grass, but not on a natural fen with a high water table. NO fluxes amounted to 16-30 % of the N{sub 2}O flux rates. The importance of the water table in regulating N{sub 2}0 fluxes was demonstrated in field and laboratory studies. It was shown in the laboratory that even a short lowering of the water table, for 14 weeks at 20 deg C, induced N{sub 2}0 fluxes from the fens that normally acted as sinks or only low sources. Raising the water table in peat monoliths from drained sites reduced the flux of N{sub 2}O. Nutrient-rich peatlands had much higher capacities for N{sub 2}O and NO production than poorer ones. The addition of KNO{sub 3}, NH{sub 4}Cl or urea to minerotrophic peat further increased the fluxes of N{sub 2}O and NO, and also nitrogen mineralisation. There was a clear connection between the fluxes of N{sub 2}0 and NO and nitrification activity measured as the numbers of nitrite

  17. Microbial production of nitrous oxide and nitric oxide in boreal peatlands

    International Nuclear Information System (INIS)

    Regina, K.

    1998-01-01

    Soils are an important source of nitrous oxide (N 2 O) and nitric oxide (NO). N 2 O is a greenhouse gas participating in both warming of the climate and the destruction of ozone, and NO is active in tropospheric chemistry. The fluxes and formation mechanisms of these gases in boreal Finnish peatlands were studied by both laboratory and field techniques. Special attention was paid to factors regulating their production, e.g. height of the water table, pH, temperature, nutrient level and nitrification activity. Both N 2 O and NO fluxes were detected in the peatlands, some of which were sources of these trace gases and some sinks. The flux rates of N 2 O ranged from negative values to several milligrammes per square metre per day. Natural peatlands were the lowest sources of N 2 O, often showing negative fluxes, whereas sites drained for forestry some decades ago had markedly higher fluxes. A site drained for agriculture (grassland) was the highest source found. NO fluxes were observed on the two drained sites studied, a forested fen and the same field of grass, but not on a natural fen with a high water table. NO fluxes amounted to 16-30 % of the N 2 O flux rates. The importance of the water table in regulating N 2 0 fluxes was demonstrated in field and laboratory studies. It was shown in the laboratory that even a short lowering of the water table, for 14 weeks at 20 deg C, induced N 2 0 fluxes from the fens that normally acted as sinks or only low sources. Raising the water table in peat monoliths from drained sites reduced the flux of N 2 O. Nutrient-rich peatlands had much higher capacities for N 2 O and NO production than poorer ones. The addition of KNO 3 , NH 4 Cl or urea to minerotrophic peat further increased the fluxes of N 2 O and NO, and also nitrogen mineralisation. There was a clear connection between the fluxes of N 2 0 and NO and nitrification activity measured as the numbers of nitrite-oxidising bacteria, nitrification potential or in situ net

  18. Microbial production of nitrous oxide and nitric oxide in boreal peatlands

    Energy Technology Data Exchange (ETDEWEB)

    Regina, K

    1999-12-31

    Soils are an important source of nitrous oxide (N{sub 2}O) and nitric oxide (NO). N{sub 2}O is a greenhouse gas participating in both warming of the climate and the destruction of ozone, and NO is active in tropospheric chemistry. The fluxes and formation mechanisms of these gases in boreal Finnish peatlands were studied by both laboratory and field techniques. Special attention was paid to factors regulating their production, e.g. height of the water table, pH, temperature, nutrient level and nitrification activity. Both N{sub 2}O and NO fluxes were detected in the peatlands, some of which were sources of these trace gases and some sinks. The flux rates of N{sub 2}O ranged from negative values to several milligrammes per square metre per day. Natural peatlands were the lowest sources of N{sub 2}O, often showing negative fluxes, whereas sites drained for forestry some decades ago had markedly higher fluxes. A site drained for agriculture (grassland) was the highest source found. NO fluxes were observed on the two drained sites studied, a forested fen and the same field of grass, but not on a natural fen with a high water table. NO fluxes amounted to 16-30 % of the N{sub 2}O flux rates. The importance of the water table in regulating N{sub 2}0 fluxes was demonstrated in field and laboratory studies. It was shown in the laboratory that even a short lowering of the water table, for 14 weeks at 20 deg C, induced N{sub 2}0 fluxes from the fens that normally acted as sinks or only low sources. Raising the water table in peat monoliths from drained sites reduced the flux of N{sub 2}O. Nutrient-rich peatlands had much higher capacities for N{sub 2}O and NO production than poorer ones. The addition of KNO{sub 3}, NH{sub 4}Cl or urea to minerotrophic peat further increased the fluxes of N{sub 2}O and NO, and also nitrogen mineralisation. There was a clear connection between the fluxes of N{sub 2}0 and NO and nitrification activity measured as the numbers of nitrite

  19. Biogeochemical controls and isotopic signatures of nitrous oxide production by a marine ammonia-oxidizing bacterium

    Directory of Open Access Journals (Sweden)

    C. H. Frame

    2010-09-01

    Full Text Available Nitrous oxide (N2O is a trace gas that contributes to the greenhouse effect and stratospheric ozone depletion. The N2O yield from nitrification (moles N2O-N produced per mole ammonium-N consumed has been used to estimate marine N2O production rates from measured nitrification rates and global estimates of oceanic export production. However, the N2O yield from nitrification is not constant. Previous culture-based measurements indicate that N2O yield increases as oxygen (O2 concentration decreases and as nitrite (NO2 concentration increases. Here, we have measured yields of N2O from cultures of the marine β-proteobacterium Nitrosomonas marina C-113a as they grew on low-ammonium (50 μM media. These yields, which were typically between 4 × 10−4 and 7 × 10−4 for cultures with cell densities between 2 × 102 and 2.1 × 104 cells ml−1, were lower than previous reports for ammonia-oxidizing bacteria. The observed impact of O2 concentration on yield was also smaller than previously reported under all conditions except at high starting cell densities (1.5 × 106 cells ml−1, where 160-fold higher yields were observed at 0.5% O2 (5.1 μM dissolved O2 compared with 20% O2 (203 μM dissolved O2. At lower cell densities (2 × 102 and 2.1 × 104 cells ml−1, cultures grown under 0.5% O2 had yields that were only 1.25- to 1.73-fold higher than cultures grown under 20% O2. Thus, previously reported many-fold increases in N2O yield with dropping O2 could be reproduced only at cell densities that far exceeded those of ammonia oxidizers in the ocean. The presence of excess NO2 (up to 1 mM in the growth

  20. Effects of garlic extract on color, lipid oxidation and oxidative breakdown products in raw ground beef during refrigerated storage

    Directory of Open Access Journals (Sweden)

    XINZHUANG ZHANG

    2016-03-01

    Full Text Available The study aims to investigate the effects of garlic extracts on color, lipid oxidation, and oxidative breakdown products in raw ground beef during refrigerated storage. The two treatments were:control group (C, with no addition and experiment group (D, 50 mg garlic extracts added to 100 g beef. Adding garlic extracts significant increased a* value (PA ≤ 0.05, and significant decreased TBARS and PV values (PA ≤ 0.05. The pH and –SH value of D group had a decreasing tendency (PA=0.0522 and an increasing tendency (PA=0.0636 respectively compared to C group. Garlic extracts protected phospholipids, fatty acids and polypeptides from oxidation. The results indicatethat garlic extracts have the antioxidant activity, helping maintain the meat color, inhibiting lipid oxidation and protein degradation of raw ground beef during refrigerated storage.

  1. 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.

  2. Highly Active and Specific Tyrosine Ammonia-Lyases from Diverse Origins Enable Enhanced Production of Aromatic Compounds in Bacteria and Saccharomyces cerevisiae

    DEFF Research Database (Denmark)

    Jendresen, Christian Bille; Stahlhut, Steen Gustav; Li, Mingji

    2015-01-01

    Phenylalanine and tyrosine ammonia-lyases form cinnamic acid and p-coumaric acid, which are precursors of a wide range of aromatic compounds of biotechnological interest. Lack of highly active and specific tyrosine ammonia-lyases has previously been a limitation in metabolic engineering approaches...

  3. Production of nitric oxide using a microwave plasma torch and its application to fungal cell differentiation

    International Nuclear Information System (INIS)

    Na, Young Ho; Kang, Min-Ho; Cho, Guang Sup; Choi, Eun Ha; Park, Gyungsoon; Uhm, Han Sup; Kumar, Naresh

    2015-01-01

    The generation of nitric oxide by a microwave plasma torch is proposed for its application to cell differentiation. A microwave plasma torch was developed based on basic kinetic theory. The analytical theory indicates that nitric oxide density is nearly proportional to oxygen molecular density and that the high-temperature flame is an effective means of generating nitric oxide. Experimental data pertaining to nitric oxide production are presented in terms of the oxygen input in units of cubic centimeters per minute. The apparent length of the torch flame increases as the oxygen input increases. The various levels of nitric oxide are observed depending on the flow rate of nitrogen gas, the mole fraction of oxygen gas, and the microwave power. In order to evaluate the potential of nitric oxide as an activator of cell differentiation, we applied nitric oxide generated from the microwave plasma torch to a model microbial cell (Neurospora crassa: non-pathogenic fungus). Germination and hyphal differentiation of fungal cells were not dramatically changed but there was a significant increase in spore formation after treatment with nitric oxide. In addition, the expression level of a sporulation related gene acon-3 was significantly elevated after 24 h upon nitric oxide treatment. Increase in the level of nitric oxide, nitrite and nitrate in water after nitric oxide treatment seems to be responsible for activation of fungal sporulation. Our results suggest that nitric oxide generated by plasma can be used as a possible activator of cell differentiation and development. (paper)

  4. Biodiesel Production from Castor Oil by Using Calcium Oxide Derived from Mud Clam Shell

    OpenAIRE

    Ismail, S.; Ahmed, A. S.; Anr, Reddy; Hamdan, S.

    2016-01-01

    The catalytic potential of calcium oxide synthesized from mud clam shell as a heterogeneous catalyst for biodiesel production was studied. The mud clam shell calcium oxide was characterized using particle size analyzer, Fourier transform infrared spectroscopy, scanning electron microscopy, and BET gas sorption analyzer. The catalyst performance of mud clam shell calcium oxide was studied in the transesterification of castor oil as biodiesel. Catalyst characterization and transesterification s...

  5. Spectrofluorimetric study of the aromatic carbohydrates of Noriisk petroleum

    Energy Technology Data Exchange (ETDEWEB)

    Alekseeva, T.A.; Lekveishvili, E.G.; Melikadze, L.D.; Teplitskaia, T.A.; Tevdorashvili, M.N.

    1979-01-01

    Investigation was made of the specimens of aromatic hydrocarbons which were produced by photochemical decomposition of the products of photocondensation with maleicanhydride of narrow aromatic fractions separated by a system of methods from a high temperature part of Noriisk petroleum. Use was made of a standard spectrofluorimeter of low resolution. A series of aromatic hydrocarbons, naphthalene, benzofluorene, phenantrene, chrizene, pyrene, tetraphene, and 3,4-benzophenantrene were installed in the machine.

  6. Method and apparatus for the production of metal oxide powder

    Science.gov (United States)

    Harris, Michael T.; Scott, Timothy C.; Byers, Charles H.

    1992-01-01

    The present invention provides a method for preparing metal oxide powder. A first solution, which is substantially organic, is prepared. A second solution, which is an aqueous solution substantially immiscible in the first solution, is prepared and delivered as drops to the first solution. The drops of the second solution are atomized by a pulsed electric field forming micro-drops of the second solution. Reagents in the first solution diffuse into and react with reactants in the micro-drops of the second solution forming metal hydroxide or oxalate particles. The metal hydroxide or metal oxalate particles are then recovered and dried to produce the metal oxide powder. An apparatus for preparing a metal oxide powder is also disclosed.

  7. Catalytic production of metal carbonyls from metal oxides

    Science.gov (United States)

    Sapienza, Richard S.; Slegeir, William A.; Foran, Michael T.

    1984-01-01

    This invention relates to the formation of metal carbonyls from metal oxides and specially the formation of molybdenum carbonyl and iron carbonyl from their respective oxides. Copper is used here in admixed form or used in chemically combined form as copper molybdate. The copper/metal oxide combination or combined copper is utilized with a solvent, such as toluene and subjected to carbon monoxide pressure of 25 atmospheres or greater at about 150.degree.-260.degree. C. The reducing metal copper is employed in catalytic concentrations or combined concentrations as CuMoO.sub.4 and both hydrogen and water present serve as promoters. It has been found that the yields by this process have been salutary and that additionally the catalytic metal may be reused in the process to good effect.

  8. Method and apparatus for the production of metal oxide powder

    Science.gov (United States)

    Harris, M.T.; Scott, T.C.; Byers, C.H.

    1992-06-16

    The present invention provides a method for preparing metal oxide powder. A first solution, which is substantially organic, is prepared. A second solution, which is an aqueous solution substantially immiscible in the first solution, is prepared and delivered as drops to the first solution. The drops of the second solution are atomized by a pulsed electric field forming micro-drops of the second solution. Reagents in the first solution diffuse into and react with reactants in the micro-drops of the second solution forming metal hydroxide or oxalate particles. The metal hydroxide or metal oxalate particles are then recovered and dried to produce the metal oxide powder. An apparatus for preparing a metal oxide powder is also disclosed. 2 figs.

  9. Enhancing Biodiesel Production Using Green Glycerol-Enriched Calcium Oxide Catalyst : An Optimization Study

    NARCIS (Netherlands)

    Avhad, Mangesh R.; Gangurde, L.S.; Sánchez, Marcos; Bouaid, Abderrahim; Aracil, José; Martínez, Mercedes; Marchetti, Jorge M.

    2018-01-01

    The present article demonstrates a superior catalytic performance of glycerol-enriched calcium oxide for biodiesel production than other calcium-based counterparts. The proficiency of glycerol-enriched calcium oxide in catalyzing the methanolysis of crude Jatropha curcas oil containing high free

  10. The degradation of lining of rotary furnaces in the production of zinc oxide

    Czech Academy of Sciences Publication Activity Database

    Luptáková, Natália; Pešlová, F.; Anisimov, E.

    2014-01-01

    Roč. 21, č. 3 (2014), s. 116-121 ISSN 1335-0803 Institutional support: RVO:68081723 Keywords : zinc oxide * the production of zinc oxide * zinc slag * refractories * the degradation of rotary furnace linings Subject RIV: JG - Metallurgy http://ojs.mateng.sk/index.php/Mateng/article/view/133/194

  11. Continuous operation of a pilot plant for the production of beryllium oxide

    Energy Technology Data Exchange (ETDEWEB)

    Costa, T C; Amaral, S; Silveira, C M.S.; de Oliveira, A P [Instituto de Tecnologia, Governador Valadares (Brazil)

    1975-12-01

    A method of obtaining beryllium oxide with a purity of 99,2% was developed in a pilot plant with a capacity of 7 tons per month destined to operate continuously. The operation market prospects and control of production with the objective of obtaining internacional technical grade beryllium oxide are discussed.

  12. Continuous operation of a pilot plant for the production of beryllium oxide

    International Nuclear Information System (INIS)

    Costa, T.C.; Amaral, S.; Silveira, C.M.S.; Oliveira, A.P. de

    1975-01-01

    A method of obtaining beryllium oxide with a purity of 99,2% was developed in a pilot plant with a capacity of 7 tons per month destined to operate continuously. The operation market prospects and control of production with the objective of obtaining internacional technical grade beryllium oxide are discussed [pt

  13. Impact of residual elements on zinc quality in the production of zinc oxide

    Czech Academy of Sciences Publication Activity Database

    Luptáková, Natália; Dymáček, Petr; Pešlová, F.; Jurkovič, Z.; Barborák, O.; Stodola, J.

    2016-01-01

    Roč. 55, č. 3 (2016), s. 407-410 ISSN 0543-5846 Institutional support: RVO:68081723 Keywords : zinc * metallography * microstructure of zinc * zinc oxide * production of zinc oxide Subject RIV: JG - Metallurgy Impact factor: 0.959, year: 2014

  14. 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...

  15. Nitrous oxide production in grassland soils: assessing the contribution of nitrifier denitrification

    NARCIS (Netherlands)

    Wrage, N.; Velthof, G.L.; Laanbroek, H.J.; Oenema, O.

    2004-01-01

    Nitrifier denitrification is the reduction of NO2- to N2 by nitrifiers. It leads to the production of the greenhouse gas nitrous oxide (N2O) as an intermediate and possible end product. It is not known how important nitrifier denitrification is for the production of N2O in soils. We explored N2O

  16. Economical feasibility of zeolite membranes for industrial scale separations of aromatic hydrocarbons

    NARCIS (Netherlands)

    Meindersma, G.W.; de Haan, A.B.

    2002-01-01

    Naphtha cracker feedstocks contain 10–25 wt% aromatic hydrocarbons, which are not converted into the desired products ethylene and propylene. The conventional processes for the separation of aromatic and aliphatic hydrocarbons are extraction, extractive distillation and azeotropic distillation.

  17. Denitrification: An important pathway for nitrous oxide production in tropical mangrove sediments (Goa, India)

    Digital Repository Service at National Institute of Oceanography (India)

    Fernandes, S.O.; LokaBharathi, P.A.; Bonin, P.C.; Michotey, V.D.

    Net nitrous oxide production and denitrification activity were measured in two mangrove ecosystems of Goa, India. The relatively pristine site Tuvem was compared to Divar, which is prone to high nutrient input. Stratified sampling at 2-cm intervals...

  18. Piper sarmentosum increases nitric oxide production in oxidative stress: a study on human umbilical vein endothelial cells.

    Science.gov (United States)

    Ugusman, Azizah; Zakaria, Zaiton; Hui, Chua Kien; Nordin, Nor Anita Megat Mohd

    2010-07-01

    Nitric oxide produced by endothelial nitric oxide synthase (eNOS) possesses multiple anti-atherosclerotic properties. Hence, enhanced expression of eNOS and increased Nitric oxide levels may protect against the development of atherosclerosis. Piper sarmentosum is a tropical plant with antioxidant and anti-inflammatory activities. This study aimed to investigate the effects of Piper sarmentosum on the eNOS and Nitric oxide pathway in cultured human umbilical vein endothelial cells (HUVECs). HUVECS WERE DIVIDED INTO FOUR GROUPS: control, treatment with 180 microM hydrogen peroxide (H(2)O(2)), treatment with 150 microg/mL aqueous extract of Piper sarmentosum, and concomitant treatment with aqueous extract of PS and H(2)O(2) for 24 hours. Subsequently, HUVECs were harvested and eNOS mRNA expression was determined using qPCR. The eNOS protein level was measured using ELISA, and the eNOS activity and Nitric oxide level were determined by the Griess reaction. Human umbilical vein endothelial cells treated with aqueous extract of Piper sarmentosum showed a marked induction of Nitric oxide. Treatment with PS also resulted in increased eNOS mRNA expression, eNOS protein level and eNOS activity in HUVECs. Aqueous extract of Piper sarmentosum may improve endothelial function by promoting NO production in HUVECs.

  19. Piper sarmentosum increases nitric oxide production in oxidative stress: a study on human umbilical vein endothelial cells

    Directory of Open Access Journals (Sweden)

    Azizah Ugusman

    2010-01-01

    Full Text Available OBJECTIVE: Nitric oxide produced by endothelial nitric oxide synthase (eNOS possesses multiple anti-atherosclerotic properties. Hence, enhanced expression of eNOS and increased Nitric oxide levels may protect against the development of atherosclerosis. Piper sarmentosum is a tropical plant with antioxidant and anti-inflammatory activities. This study aimed to investigate the effects of Piper sarmentosum on the eNOS and Nitric oxide pathway in cultured human umbilical vein endothelial cells (HUVECs. METHODS: HUVECs were divided into four groups: control, treatment with 180 μM hydrogen peroxide (H2O2, treatment with 150 μg/mL aqueous extract of Piper sarmentosum, and concomitant treatment with aqueous extract of PS and H2O2 for 24 hours. Subsequently, HUVECs were harvested and eNOS mRNA expression was determined using qPCR. The eNOS protein level was measured using ELISA, and the eNOS activity and Nitric oxide level were determined by the Griess reaction. RESULTS: Human umbilical vein endothelial cells treated with aqueous extract of Piper sarmentosum showed a marked induction of Nitric oxide. Treatment with PS also resulted in increased eNOS mRNA expression, eNOS protein level and eNOS activity in HUVECs. CONCLUSION: Aqueous extract of Piper sarmentosum may improve endothelial function by promoting NO production in HUVECs.

  20. Oxidative and nonoxidative metabolism of polycyclic aromatic hydrocarbons in rabbit and chicken aortas and in human fetal smooth-muscle cells

    International Nuclear Information System (INIS)

    Bond, J.A.; Kocan, R.M.; Benditt, E.P.; Juchau, M.R.

    1980-01-01

    A description of the various enzyme systems in aortas of rabbits and chickens and in human fetal smooth muscle cells in culture which are responsible overall for the metabolism of F, 12-dimethylbenz(a)anthracene and benzo(a)pyrene-4, 5-oxide are provided

  1. CYP63A2, a catalytically versatile fungal P450 monooxygenase capable of oxidizing higher-molecular-weight polycyclic aromatic hydrocarbons, alkylphenols, and alkanes

    Science.gov (United States)

    Cytochrome P450 monooxygenases (P450s) are known to oxidize hydrocarbons albeit with limited substrate specificity across classes of these compounds. Here we report a P450 monooxygenase (CYP63A2) from the model ligninolytic white rot fungus Phanerochaete chrysosporium that was fo...

  2. Mn(II) oxidation by an ascomycete fungus is linked to superoxide production during asexual reproduction.

    Science.gov (United States)

    Hansel, Colleen M; Zeiner, Carolyn A; Santelli, Cara M; Webb, Samuel M

    2012-07-31

    Manganese (Mn) oxides are among the most reactive minerals within the environment, where they control the bioavailability of carbon, nutrients, and numerous metals. Although the ability of microorganisms to oxidize Mn(II) to Mn(III/IV) oxides is scattered throughout the bacterial and fungal domains of life, the mechanism and physiological basis for Mn(II) oxidation remains an enigma. Here, we use a combination of compound-specific chemical assays, microspectroscopy, and electron microscopy to show that a common Ascomycete filamentous fungus, Stilbella aciculosa, oxidizes Mn(II) to Mn oxides by producing extracellular superoxide during cell differentiation. The reactive Mn oxide phase birnessite and the reactive oxygen species superoxide and hydrogen peroxide are colocalized at the base of asexual reproductive structures. Mn oxide formation is not observed in the presence of superoxide scavengers (e.g., Cu) and inhibitors of NADPH oxidases (e.g., diphenylene iodonium chloride), enzymes responsible for superoxide production and cell differentiation in fungi. Considering the recent identification of Mn(II) oxidation by NADH oxidase-based superoxide production by a common marine bacterium (Roseobacter sp.), these results introduce a surprising homology between some prokaryotic and eukaryotic organisms in the mechanisms responsible for Mn(II) oxidation, where oxidation appears to be a side reaction of extracellular superoxide production. Given the versatility of superoxide as a redox reactant and the widespread ability of fungi to produce superoxide, this microbial extracellular superoxide production may play a central role in the cycling and bioavailability of metals (e.g., Hg, Fe, Mn) and carbon in natural systems.

  3. Pitfalls in measuring nitrous oxide production by nitrifiers

    NARCIS (Netherlands)

    Wrage, N.

    2003-01-01

    Nitrous oxide (N 2 O) is an important greenhouse gas. At present, it causes 6% of global warming. The atmospheric concentration of N 2 O continues to increase at a rate of 0.8 ppb per year. The main known sink of N 2 O is its destruction in the stratosphere to

  4. Serum Iron and Nitric Oxide Production in Trypanosoma brucei ...

    African Journals Online (AJOL)

    JTEkanem

    reduction in the serum iron status and a modulation of nitric oxide synthase activity of T. brucei infected rats. ... inflammation and tissue damage15. ... The serum iron level was determined ... concentration or of total nitrate and nitrite ... 15. 16. 17. 18. Days. S e ru m iro n lev e l mg. /ml. Infected treated. Infected untreated. 0.

  5. Nitrous oxide production by lithotrophic ammonia-oxidizing bacteria and implications for engineered nitrogen-removal systems.

    Science.gov (United States)

    Chandran, Kartik; Stein, Lisa Y; Klotz, Martin G; van Loosdrecht, Mark C M

    2011-12-01

    Chemolithoautotrophic AOB (ammonia-oxidizing bacteria) form a crucial component in microbial nitrogen cycling in both natural and engineered systems. Under specific conditions, including transitions from anoxic to oxic conditions and/or excessive ammonia loading, and the presence of high nitrite (NO₂⁻) concentrations, these bacteria are also documented to produce nitric oxide (NO) and nitrous oxide (N₂O) gases. Essentially, ammonia oxidation in the presence of non-limiting substrate concentrations (ammonia and O₂) is associated with N₂O production. An exceptional scenario that leads to such conditions is the periodical switch between anoxic and oxic conditions, which is rather common in engineered nitrogen-removal systems. In particular, the recovery from, rather than imposition of, anoxic conditions has been demonstrated to result in N₂O production. However, applied engineering perspectives, so far, have largely ignored the contribution of nitrification to N₂O emissions in greenhouse gas inventories from wastewater-treatment plants. Recent field-scale measurements have revealed that nitrification-related N₂O emissions are generally far higher than emissions assigned to heterotrophic denitrification. In the present paper, the metabolic pathways, which could potentially contribute to NO and N₂O production by AOB have been conceptually reconstructed under conditions especially relevant to engineered nitrogen-removal systems. Taken together, the reconstructed pathways, field- and laboratory-scale results suggest that engineering designs that achieve low effluent aqueous nitrogen concentrations also minimize gaseous nitrogen emissions.

  6. Does increased Nitric Oxide production and oxidative stress due to high fat diet affect cardiac function after myocardial infarction?

    Directory of Open Access Journals (Sweden)

    Marjan Aghajani

    2017-01-01

    Full Text Available Background &Objectives: High fat (HF diet by affecting the oxidative stress and nitric oxide (NO production may lead to different effects on function of the heart after myocardial infarction (MI. In the present study we aimed to address the hypothesis that high release of NO by activated macrophages affects LV function after MI.Methods: The animals were randomly divided into four groups comprising each of 10 rats: 1 Sham; 2 MI; 3 Sham+ HF diet; 4 MI+ HF diet. Animals fed with HF diet 30 days before sham and MI surgery. MI was induced by permanent ligation of left anterior descending coronary artery (LAD. Nitric oxide (NO production of peritoneal macrophages, the concentrations of MDA in the heart and the infarct size were measured.Results: Our study indicated that HF has adverse effects on myocardium and it may increase NO production as well as oxidative stress, resulting in augmentation of infarct size.Conclusion: Our results add to our knowledge that HF diet was associated with overproduction of NO by peritoneal macrophages and ROS that lead to development of infarct size and adverse remodeling.

  7. Aromatic hydrocarbons in produced water from offshore oil and gas production. Test of sample strategy; Aromatiske kulbrinter i produceret vand fra offshore olie- og gas industrien. Test af proevetagningsstrategi

    Energy Technology Data Exchange (ETDEWEB)

    Hansen, A.

    2005-07-01

    In co-operation with the Danish EPA, the National Environmental Research Institute (NERI) has carried out a series of measurements of aromatic hydrocarbons in produced water from an offshore oil and gas production platform in the Danish sector of the North Sea as part of the project 'Testing of sampling strategy for aromatic hydrocarbons in produced water from the offshore oil and gas industry'. The measurements included both volatile (BTEX: benzene, toluene, ethylbenzene and xylenes) and semi-volatile aromatic hydrocarbons: NPD (naphthalenes, phenanthrenes and dibenzothiophenes) and selected PAHs (polycyclic aromatic hydrocarbons). In total, 12 samples of produced water were sampled at the Dan FF production platform located in the North Sea by the operator, Maersk Oil and Gas, as four sets of three parallel samples from November 24 - December 02, 2004. After collection of the last set, the samples were shipped to NERI for analysis. The water samples were collected in 1 L glass bottles that were filled completely (without overfilling) and tightly closed. After sampling, the samples were preserved with hydrochloric acid and cooled below ambient until being shipped off to NERI. Here all samples were analysed in dublicates, and the results show that for BTEX, levels were reduced compared to similar measurements carried out by NERI in 2002 and others. In this work, BTEX levels were approximately 5 mg/L, while similar studies showed levels in the range 0,5 - 35 mg/L. For NPD levels were similar, 0,5 - 1,4 mg/L, while for PAH they seerred elevated; 0,1 - 0,4 mg/L in this work compared to 0,001 - 0,3 mg/L in similar studies. The applied sampling strategy has been tested by performing analysis of variance on the analytical data. The test of the analytical data has shown that the mean values of the three parallel samples collected in series constituted a good estimate of the levels at the time of sampling; thus, the variance between the parallel samples was not

  8. Intensity of lipid oxidation and formation of cholesterol oxidation products during frozen storage of raw and cooked chicken

    OpenAIRE

    Conchillo, A. (Ana); Ansorena, D. (Diana); Astiasarán, I. (Iciar)

    2004-01-01

    Raw and cooked chicken breasts were stored at −18 °C for 3 months under aerobic and vacuum conditions, and the intensity of lipid oxidation and the formation of COP (cholesterol oxidation products) were studied. Raw samples showed low COP levels (4.60–7.40 µg g−1 fat), TBARS (thiobarbituric acid reactive substances) levels (0.01–0.03 mg kg−1) and peroxide values (not detected) under both aerobic and vacuum conditions. Cooked samples (grilled and roasted) showed TBARS levels of 0.36–0.99 mg kg...

  9. Global aromatics supply. Today and tomorrow

    Energy Technology Data Exchange (ETDEWEB)

    Bender, M. [BASF SE, Ludwigshafen (Germany)

    2013-11-01

    Aromatics are the essential building blocks for some of the largest petrochemical products in today's use. To the vast majority they are consumed to produce intermediates for polymer products and, hence, contribute to our modern lifestyle. Their growth rates are expected to be in line with GDP growth in future. This contrasts the significantly lower growth rates of the primary sources for aromatics - fuel processing and steam cracking of naphtha fractions. A supply gap can be expected to open up in future for which creative solutions will be required. (orig.)

  10. Secondary organic aerosol production from pinanediol, a semi-volatile surrogate for first-generation oxidation products of monoterpenes

    Science.gov (United States)

    Ye, Penglin; Zhao, Yunliang; Chuang, Wayne K.; Robinson, Allen L.; Donahue, Neil M.

    2018-05-01

    We have investigated the production of secondary organic aerosol (SOA) from pinanediol (PD), a precursor chosen as a semi-volatile surrogate for first-generation oxidation products of monoterpenes. Observations at the CLOUD facility at CERN have shown that oxidation of organic compounds such as PD can be an important contributor to new-particle formation. Here we focus on SOA mass yields and chemical composition from PD photo-oxidation in the CMU smog chamber. To determine the SOA mass yields from this semi-volatile precursor, we had to address partitioning of both the PD and its oxidation products to the chamber walls. After correcting for these losses, we found OA loading dependent SOA mass yields from PD oxidation that ranged between 0.1 and 0.9 for SOA concentrations between 0.02 and 20 µg m-3, these mass yields are 2-3 times larger than typical of much more volatile monoterpenes. The average carbon oxidation state measured with an aerosol mass spectrometer was around -0.7. We modeled the chamber data using a dynamical two-dimensional volatility basis set and found that a significant fraction of the SOA comprises low-volatility organic compounds that could drive new-particle formation and growth, which is consistent with the CLOUD observations.

  11. Enhancing the laccase production and laccase gene expression in the white-rot fungus Trametes velutina 5930 with great potential for biotechnological applications by different metal ions and aromatic compounds.

    Directory of Open Access Journals (Sweden)

    Yang Yang

    Full Text Available Laccase is useful for various biotechnological and industrial applications. The white-rot fungus Trametes velutina 5930 and its laccase, isolated from the Shennongjia Nature Reserve in China by our laboratory, has great potential for practical application in environmental biotechnology. However, the original level of laccase produced by Trametes velutina 5930 was relatively low in the absence of any inducer. Therefore, in order to enhance the laccase production by Trametes velutina 5930 and make better use of this fungus in the field of environmental biotechnology, the regulation of laccase production and laccase gene expression in Trametes velutina 5930 were investigated in this study. Different metal ions such as Cu(2+ and Fe(2+ could stimulate the laccase synthesis and laccase gene transcription in Trametes velutina 5930. Some aromatic compounds structurally related to lignin, such as tannic acid, syringic acid, cinnamic acid, gallic acid and guaiacol, could also enhance the level of laccase activity and laccase gene transcription. We also found that there existed a positive synergistic effect of aromatic compound and metal ion on the laccase production and laccase gene transcription in Trametes velutina 5930. Taken together, our study may contribute to the improvement of laccase productivity by Trametes velutina 5930.

  12. Enhancing the laccase production and laccase gene expression in the white-rot fungus Trametes velutina 5930 with great potential for biotechnological applications by different metal ions and aromatic compounds.

    Science.gov (United States)

    Yang, Yang; Wei, Fuxiang; Zhuo, Rui; Fan, Fangfang; Liu, Huahua; Zhang, Chen; Ma, Li; Jiang, Mulan; Zhang, Xiaoyu

    2013-01-01

    Laccase is useful for various biotechnological and industrial applications. The white-rot fungus Trametes velutina 5930 and its laccase, isolated from the Shennongjia Nature Reserve in China by our laboratory, has great potential for practical application in environmental biotechnology. However, the original level of laccase produced by Trametes velutina 5930 was relatively low in the absence of any inducer. Therefore, in order to enhance the laccase production by Trametes velutina 5930 and make better use of this fungus in the field of environmental biotechnology, the regulation of laccase production and laccase gene expression in Trametes velutina 5930 were investigated in this study. Different metal ions such as Cu(2+) and Fe(2+) could stimulate the laccase synthesis and laccase gene transcription in Trametes velutina 5930. Some aromatic compounds structurally related to lignin, such as tannic acid, syringic acid, cinnamic acid, gallic acid and guaiacol, could also enhance the level of laccase activity and laccase gene transcription. We also found that there existed a positive synergistic effect of aromatic compound and metal ion on the laccase production and laccase gene transcription in Trametes velutina 5930. Taken together, our study may contribute to the improvement of laccase productivity by Trametes velutina 5930.

  13. An economic route to mass production of graphene oxide solution for preparing graphene oxide papers

    Energy Technology Data Exchange (ETDEWEB)

    Liou, Yan-Jia; Tsai, Bo-Da; Huang, Wu-Jang, E-mail: wjhuang@mail.npust.edu.tw

    2015-03-15

    Highlights: • Graphene oxide paper can be prepared from synthesized graphene sheet containing carbon materials. • Graphene oxide paper can be used as a phase change materials for thermal storage. • To prepare graphene oxide paper from synthesized graphene sheet containing carbon materials could highly reduce the cost. - Abstract: Graphene oxide paper (GOP) is a composite material fabricated from graphene oxide (GO) solution. In addition, it can be a novel and potential material for application on the separation of water vapor from gaseous steam or larger alkali ions from aqueous solution. GOP could be used as electricity and thermal storage materials. The preparation of GO commonly uses high purity natural or artificial graphite. It is difficult to prepare GOP from artificial graphite powder due to the cost of $1,450 US/ton. In this study, we tried to prepare GOPs from homemade graphene sheets containing carbon materials (GSCCMs) and evaluate the thermal properties of GSCCM derived GOPs. Results show that GSCCM derived GOPs have a higher phase transition temperature, and the average mesophase phase change enthalpy is 9.41 J/g, which is 2.87 times higher than graphite derived GOP. Therefore, to prepare GOP from GSCCMs could highly reduce the cost.

  14. Quantitation of chlorophylls and 22 of their colored degradation products in culinary aromatic herbs by HPLC-DAD-MS and correlation with color changes during the dehydration process.

    Science.gov (United States)

    Lafeuille, Jean-Louis; Lefèvre, Stéphane; Lebuhotel, Julie

    2014-02-26

    Chlorophylls and their green and olive-brown derivatives were successfully separated from culinary herb extracts by HPLC with photodiode-array and mass spectrometry detection. The method involved a ternary gradient elution and reverse-phase separation conditions capable of resolving 24 different pigments (2 chlorophylls and 22 of their derivatives) of different polarities within 28 min. The method was applied to monitor color changes in 50 samples of culinary aromatic herbs subjected to five different drying treatments. Of the 24 pigments, 14 were key to understanding the differences between the primary degradation pathways of chlorophyll a and chlorophyll b in culinary herbs during drying processes. A color degradation ladder based on the total molar percentage of all the remaining green pigments was also proposed as a tool to measure the impact of drying treatments on aromatic herb visual aspects.

  15. The relationship between biomarkers of oxidative DNA damage, polycyclic aromatic hydrocarbon DNA adducts, antioxidant status and genetic susceptibility following exposure to environmental air pollution in humans

    Czech Academy of Sciences Publication Activity Database

    Shing, R.; Šrám, Radim; Binková, Blanka; Kalina, I.; Popov, T. A.; Georgieva, T.; Garte, S.; Taioli, E.; Farmer, P. B.

    2007-01-01

    Roč. 620, - (2007), s. 83-92 ISSN 0027-5107 Grant - others:EU(GB) 2000-00091; EU(GB) G0100873 Institutional research plan: CEZ:AV0Z50390512 Source of funding: R - rámcový projekt EK ; R - rámcový projekt EK Keywords : air pollution * PAHs * oxidative DNA damage Subject RIV: DN - Health Impact of the Environment Quality Impact factor: 4.159, year: 2007

  16. Production of oxidatively stable fish oil enriched food emulsions

    DEFF Research Database (Denmark)

    Bruni Let, Mette

    Purpose: The objective of the project is to determine how a number of selected fish oil enriched foods can be protected against oxidation by the right choice of antioxidants, emulsifiers and optimal process conditions. Furthermore the influence of antioxidant addition to the fish oil it...... have many other health benefiting properties such as preventing heart diseases. Addition of fish oils to foods is therefore of interest. The many double bonds in the fatty acids are however susceptible to oxidation. Collaboration partners: The project is a collaborative project between DFU-FF, Bio......-self on the effect of antioxidants added to the foods will also be investigated. Background: Fish oils are rich sources of the long-chain polyunsaturated fatty acids EPA and DHA of which DHA is a vital component of the phospholipids of human cellular membranes, especially those in the brain and retina. Fish oils...

  17. Density functional theory studies on electronic properties of thiophene s oxides as aromatic dienophiles for reactivity prediction in diels-alder reactions

    International Nuclear Information System (INIS)

    Banjo, S.

    2013-01-01

    The reactivity of thiophene S-oxides was discussed with special emphasis on the use of thiophene S-oxides as dienophiles in Diels-Alder type reactions. The omega values obtained for thiophene S-oxide (TO) with electron-donating group (-CH/sub 3/) increased the nucleophilicity power whereas substitution with electron-withdrawing groups (such as -NO/sub 2/ and -CO/sub 2/CH/sub 2/CH/sub 3/) increased the electrophilicity power, indicating an increase of reactivity towards a nucleophiles. The higher the value of delta omega the more favourable the D-A process, therefore apart from (4+2) addition reactions of these TO as diene with the typical dienophiles like 1,2-dicyanoethene and 1,2-dicyanoethene, it could be possible for TO with strong electron withdrawing substituents to serve as dienophile, e.g. heterocycles Ie and If. Also, from the value of delta omega heterocycle 1d could involve in (4+2) addition reactions with heterocyles 1e and If. (author)

  18. Inhibition of oxidant production in rat adjuvant arthritis with perostilbene

    Czech Academy of Sciences Publication Activity Database

    Perečko, T.; Drábiková, K.; Nosáľ, R.; Harmatha, Juraj; Bauerová, K.; Mihalová, D.; Jančinová, V.

    2010-01-01

    Roč. 3, č. 3 (2010), A73-A74 ISSN 1337-6853. [Toxcon 2010, Borderless Toxicology. 15th Interdisciplinary Toxicological Conference & Advanced Toxicological Course. 06.09.-10.09.2010, Stará Lesná - Hotel Academia] R&D Projects: GA ČR(CZ) GA203/07/1227 Institutional research plan: CEZ:AV0Z40550506 Keywords : stilbene type polyphenols * antiinflammatory * oxidative burst of neutrophils Subject RIV: CC - Organic Chemistry

  19. Base-catalyzed efficient tandem [3 + 3] and [3 + 2 + 1] annulation-aerobic oxidative benzannulations.

    Science.gov (United States)

    Diallo, Aboubacar; Zhao, Yu-Long; Wang, He; Li, Sha-Sha; Ren, Chuan-Qing; Liu, Qun

    2012-11-16

    An efficient synthesis of substituted benzenes via a base-catalyzed [3 + 3] aerobic oxidative aromatization of α,β-unsaturated carbonyl compounds with dimethyl glutaconate was reported. All the reactions were carried out under mild, metal-free conditions to afford the products in high to excellent yields with molecular oxygen as the sole oxidant and water as the sole byproduct. Furthermore, a more convenient tandem [3 + 2 + 1] aerobic oxidative aromatization reaction was developed through the in situ generation of the α,β-unsaturated carbonyl compounds from aldehydes and ketones.

  20. A Study on the Oxidative-dissolution Leaching of Fission Product Oxides in the carbonate solution

    International Nuclear Information System (INIS)

    Lee, Eil Hee; Kim, Kwang Wook; Lim, Jae Gwan; Chung, Dong Yong; Yang, Han Beom; Joe, Kih Soo; Seo, Heui Seung; Kim, Yeon Hwa; Lee, Se Yoon

    2009-07-01

    This study was carried out to investigate the characteristics of an oxidativedissolution leaching of FP co-dissolved with U in a carbonate solution of Na 2 CO 3 - H 2 O 2 and (NH 4 ) 2 CO 3 -H 2 O 2 , respectively. Simulated FP-oxides which contained 12 components have been added to the solution to examine their oxidative dissolution characteristics. It was found that H 2 O 2 was an effective oxidant to minimize the dissolution of FP in a carbonate solution. In 0.5M Na 2 CO 3 -0.5M H 2 O 2 and 0.5M (NH 4 ) 2 CO 3 -0.5M H 2 O 2 solution, some elements such as Re, Te, Cs and Mo seem to be dissolved together with U. It is revealed that dissolution rates of Re, Te and Cs are high (completely dissolved within 10∼20 minutes) due to their high solubility in Na 2 CO 3 and (NH 4 ) 2 CO 3 solution regardless of the addition of H 2 O 2 , and independent of the concentrations of Na 2 CO 3 and H 2 O 2 . However, Mo was slowly dissolved by an oxidative dissolution with H 2 O 2 . It is found that the most important factor for the oxidative dissolution of FP is the pH of the solution and an effective oxidative dissolution is achieved at a pH between 10∼12 for Na 2 CO 3 and a pH between 9∼10 for (NH 4 ) 2 CO 3 , respectively, in order to minimize the dissolution of FP

  1. Oxidative Stability and Sensory Attributes of Fermented Milk Product Fortified with Fish Oil and Marine Phospholipids

    DEFF Research Database (Denmark)

    Lu, Henna Fung Sieng; Thomsen, Birgitte Raagaard; Hyldig, Grethe

    2013-01-01

    Marine phospholipids (PL) are potential ingredients for food fortification due to its numerous advantages. The main objective of this study was to investigate whether a fermented milk product fortified with a mixture of marine PL and fish oil had better oxidative stability than a fermented milk...... product fortified with fish oil alone. Fortification of a fermented milk product with marine PL was performed by incorporating 1 % w/w lipids, either in the form of neat oil or in the form of a pre-emulsion. Lipid oxidation was investigated in the neat emulsions and fortified products by the measurements...... of primary, secondary volatile oxidation products and tocopherol content upon 32 days storage at 2 °C and 28 days storage at 5 °C, respectively. Analyses of particle size distribution, viscosity and microbial growth were also performed. In addition, sensory attributes such as sour, fishy and rancid flavor...

  2. An investigation of oxidation products and SOA yields from OH + pesticide reactions

    Science.gov (United States)

    Murschell, T.; Friedman, B.; Link, M.; Farmer, D.

    2016-12-01

    Pesticides are used globally in agricultural and residential areas. After application and/or volatilization from a surface, these compounds can be transported over long distances in the atmosphere. However, their chemical fate, including oxidation and gas-particle partitioning in the atmosphere, is not well understood. We present gas and particle measurements of oxidation products from pesticide + OH reactions using a dynamic solution injection system coupled to an Oxidative Flow Reactor. Products were detected with a High Resolution Time of Flight Iodide Chemical Mass Spectrometer (HR-ToF-CIMS) and a Size Mobility Particle Scanner (SMPS). The OFR allows pesticides to react with variable OH radical exposures, ranging from the equivalent of one day to a full week of atmospheric oxidative aging. In this work, we explore pesticide oxidation products from reaction with OH and ozone, and compare those products to photolysis reactions. Pesticides of similar chemical structures were explored, including acetochlor / metolachlor and permethrin / cypermethrin, to explore mechanistic differences. We present chemical parameters including average product oxidation state, average oxygen to carbon ratio, and potential secondary organic aerosol formation for each of these compounds.

  3. Characterization of degradation products from alkaline wet oxidation of wheat straw

    DEFF Research Database (Denmark)

    Klinke, H.B.; Ahring, B.K.; Schmidt, A.S.

    2002-01-01

    to their chemical structure, e.g. diacids (oxalic and succinic acids), furan aldehydes, phenol aldehydes, phenol ketones and phenol acids. Aromatic aldehyde formation was correlated to severe conditions with high temperatures and low pH. Apart from CO2 and water, carboxylic acids were the main degradation products...... degreesC with addition of 12 bar oxygen and 6.5 g l(-1) Na2CO3. At these conditions the hemicellulose fraction from 100 g straw consisted of soluble hemicellulose (16 g), low molecular weight carboxylic acids (11 g), monomeric phenols (0.48 g) and 2-furoic acid (0.01 g). Formic acid and acetic acid...... constituted the majority of degradation products (8.5 g). The main phenol monomers were 4-hydroxybenzaldehyde, vanillin, syringaldehyde, acetosyringone (4-hydroxy-3,5-dimethoxy-acetophenone), vanillic acid and syringic acid, occurring in 0.04-0.12 g per 100 g straw concentrations. High lignin removal from...

  4. Molecular basis for arsenic-Induced alteration in nitric oxide production and oxidative stress: implication of endothelial dysfunction

    International Nuclear Information System (INIS)

    Kumagai, Yoshito; Pi Jingbo

    2004-01-01

    Accumulated epidemiological studies have suggested that prolonged exposure of humans to arsenic in drinking water is associated with vascular diseases. The exact mechanism of how this occurs currently unknown. Nitric oxide (NO), formed by endothelial NO synthase (eNOS), plays a crucial role in the vascular system. Decreased availability of biologically active NO in the endothelium is implicated in the pathophysiology of several vascular diseases and inhibition of eNOS by arsenic is one of the proposed mechanism s for arsenic-induced vascular diseases. In addition, during exposure to arsenic, overproduction of reactive oxygen species (ROS) can occur, resulting in oxidative stress, which is another major risk factor for vascular dysfunction. The molecular basis for decreased NO levels and increased oxidative stress during arsenic exposure is poorly understood. In this article, evidence for arsenic-mediated alteration in NO production and oxidative stress is reviewed. The results of a cross-sectional study in an endemic area of chronic arsenic poisoning and experimental animal studies to elucidate a potential mechanism for the impairment of NO formation and oxidative stress caused by prolonged exposure to arsenate in the drinking water are also reviewed

  5. Microwave- and Ultrasound-Accelerated Green Permanganate Oxidation of Thioethers

    DEFF Research Database (Denmark)

    Luu, Thi Xuan Thi; Le, Huu Tan; Le, Thach Ngoc

    2015-01-01

    Product formation from the solvent-free oxidation of aliphatic, cyclic or aromatic thioethers by permanganate supported on copper sulfate pentahydrate has been investigated in detail with respect to the importance of the nature of thioethers, the molar ratio of potassium permanganate absorbed...

  6. Circulating nitric oxide products do not solely reflect nitric oxide release in cirrhosis and portal hypertension

    DEFF Research Database (Denmark)

    Afzelius, Pia; Bazeghi, Nassim; Bie, Peter

    2011-01-01

    Patients with cirrhosis often develop a systemic vasodilatation and a hyperdynamic circulation with activation of vasoconstrictor systems such as the renin-angiotensin-aldosterone system (RAAS), and vasopressin. Increased nitric oxide (NO) synthesis has been implicated in the development of this ...

  7. Effect of influenza vaccination on oxidative stress products in breath.

    Science.gov (United States)

    Phillips, Michael; Cataneo, Renee N; Chaturvedi, Anirudh; Danaher, Patrick J; Devadiga, Anantrai; Legendre, David A; Nail, Kim L; Schmitt, Peter; Wai, James

    2010-06-01

    Viral infections cause increased oxidative stress, so a breath test for oxidative stress biomarkers (alkanes and alkane derivatives) might provide a new tool for early diagnosis. We studied 33 normal healthy human subjects receiving scheduled treatment with live attenuated influenza vaccine (LAIV). Each subject was his or her own control, since they were studied on day 0 prior to vaccination, and then on days 2, 7 and 14 following vaccination. Breath volatile organic compounds (VOCs) were collected with a breath collection apparatus, then analyzed by automated thermal desorption with gas chromatography and mass spectroscopy. A Monte Carlo simulation technique identified non-random VOC biomarkers of infection based on their C-statistic values (area under curve of receiver operating characteristic). Treatment with LAIV was followed by non-random changes in the abundance of breath VOCs. 2, 8-Dimethyl-undecane and other alkane derivatives were observed on all days. Conservative multivariate models identified vaccinated subjects on day 2 (C-statistic = 0.82, sensitivity = 63.6% and specificity = 88.5%); day 7 (C-statistic = 0.94, sensitivity = 88.5% and specificity = 92.3%); and day 14 (C-statistic = 0.95, sensitivity = 92.3% and specificity = 92.3%). The altered breath VOCs were not detected in live attenuated influenza vaccine, excluding artifactual contamination. LAIV vaccination in healthy humans elicited a prompt and sustained increase in breath biomarkers of oxidative stress. A breath test for these VOCs could potentially identify humans who are acutely infected with influenza, but who have not yet developed clinical symptoms or signs of disease.

  8. Production of the oxidation-resistant polypropylene track membranes

    International Nuclear Information System (INIS)

    Kravets, L.I.; Dmitriev, S.N.; Apel, P.Y.

    1999-01-01

    This paper describes results of the method of manufacturing the polypropylene track membranes produced by physicochemical treatment under irradiation of accelerated heavy ions of polymer films. The developed method allows to produce membranes 0.1 - 0.2 μm in diameter and more with an improved structural and physicochemical properties. Poly-propylene track membranes of a novel sample are characterized by high homogeneity of pore sizes in magnitude, considerable mechanical strength, advanced thermal stability and resistance to oxidation in aggressive media. It opens new fields for their usage

  9. Production of zinc oxide nanowires power with precisely defined morphology

    Czech Academy of Sciences Publication Activity Database

    Mičová, J.; Remeš, Zdeněk; Chang, Yu-Ying

    2017-01-01

    Roč. 68, č. 7 (2017), s. 66-69 ISSN 1335-3632 R&D Projects: GA ČR GC16-10429J Grant - others:AV ČR(CZ) KONNECT-007 Program:Bilaterální spolupráce Institutional support: RVO:68378271 Keywords : zinc oxide nanowires * hydrothermal growth method * scanning electron microscopy (SEM) Subject RIV: BM - Solid Matter Physics ; Magnetism OBOR OECD: Condensed matter physics (including formerly solid state physics, supercond.) Impact factor: 0.483, year: 2016

  10. TiO2 assisted photo-oxidative pretreatment of wheat straw for biogas production

    DEFF Research Database (Denmark)

    Awais, Muhammad; Alvarado-Morales, Merlin; Tsapekos, Panagiotis

    Photo-catalytic oxidation is an advanced oxidation process in which a catalyst is used to absorb light energy and oxidize the target substrates such as organic polymers. A number of metal oxides and metal ions can efficiently increase substrate’s depolymerisation during the process of photo...... to be markedly higher in the pretreated samples that were exposed for 180min with 1.5 wt% and 2 wt% of TiO2 compared to the untreated wheat straw. Moreover, it was concluded that the products of lignin oxidation and also, the presence of TiO2 did not inhibit the AD process. Finally, UV treatment or TiO2 alone......-catalytic oxidation. Titanium oxide (TiO2) is a photo-catalyst that in its rutile and anatase forms presents the property to enhance the photo-oxidation of lignin-containing substrates. Due to lignin is one of the major obstacles in methane production from lignocellulosic biomass, its destruction is a necessary step...

  11. Biotransformation of the high-molecular weight polycyclic aromatic hydrocarbon (PAH) benzo[k]fluoranthene by Sphingobium sp. strain KK22 and identification of new products of non-alternant PAH biodegradation by liquid chromatography electrospray ionization tandem mass spectrometry

    Science.gov (United States)

    Maeda, Allyn H; Nishi, Shinro; Hatada, Yuji; Ozeki, Yasuhiro; Kanaly, Robert A

    2014-01-01

    A pathway for the biotransformation of the environmental pollutant and high-molecular weight polycyclic aromatic hydrocarbon (PAH) benzo[k]fluoranthene by a soil bacterium was constructed through analyses of results from liquid chromatography negative electrospray ionization tandem mass spectrometry (LC/ESI(–)-MS/MS). Exposure of Sphingobium sp. strain KK22 to benzo[k]fluoranthene resulted in transformation to four-, three-and two-aromatic ring products. The structurally similar four-and three-ring non-alternant PAHs fluoranthene and acenaphthylene were also biotransformed by strain KK22, and LC/ESI(–)-MS/MS analyses of these products confirmed the lower biotransformation pathway proposed for benzo[k]fluoranthene. In all, seven products from benzo[k]fluoranthene and seven products from fluoranthene were revealed and included previously unreported products from both PAHs. Benzo[k]fluoranthene biotransformation proceeded through ortho-cleavage of 8,9-dihydroxy-benzo[k]fluoranthene to 8-carboxyfluoranthenyl-9-propenic acid and 9-hydroxy-fluoranthene-8-carboxylic acid, and was followed by meta-cleavage to produce 3-(2-formylacenaphthylen-1-yl)-2-hydroxy-prop-2-enoic acid. The fluoranthene pathway converged with the benzo[k]fluoranthene pathway through detection of the three-ring product, 2-formylacenaphthylene-1-carboxylic acid. Production of key downstream metabolites, 1,8-naphthalic anhydride and 1-naphthoic acid from benzo[k]fluoranthene, fluoranthene and acenaphthylene biotransformations provided evidence for a common pathway by strain KK22 for all three PAHs through acenaphthoquinone. Quantitative analysis of benzo[k]fluoranthene biotransformation by strain KK22 confirmed biodegradation. This is the first pathway proposed for the biotransformation of benzo[k]fluoranthene by a bacterium. PMID:24325265

  12. Biotransformation of the high-molecular weight polycyclic aromatic hydrocarbon (PAH) benzo[k]fluoranthene by Sphingobium sp. strain KK22 and identification of new products of non-alternant PAH biodegradation by liquid chromatography electrospray ionization tandem mass spectrometry.

    Science.gov (United States)

    Maeda, Allyn H; Nishi, Shinro; Hatada, Yuji; Ozeki, Yasuhiro; Kanaly, Robert A

    2014-03-01

    A pathway for the biotransformation of the environmental pollutant and high-molecular weight polycyclic aromatic hydrocarbon (PAH) benzo[k]fluoranthene by a soil bacterium was constructed through analyses of results from liquid chromatography negative electrospray ionization tandem mass spectrometry (LC/ESI(-)-MS/MS). Exposure of Sphingobium sp. strain KK22 to benzo[k]fluoranthene resulted in transformation to four-, three- and two-aromatic ring products. The structurally similar four- and three-ring non-alternant PAHs fluoranthene and acenaphthylene were also biotransformed by strain KK22, and LC/ESI(-)-MS/MS analyses of these products confirmed the lower biotransformation pathway proposed for benzo[k]fluoranthene. In all, seven products from benzo[k]fluoranthene and seven products from fluoranthene were revealed and included previously unreported products from both PAHs. Benzo[k]fluoranthene biotransformation proceeded through ortho-cleavage of 8,9-dihydroxy-benzo[k]fluoranthene to 8-carboxyfluoranthenyl-9-propenic acid and 9-hydroxy-fluoranthene-8-carboxylic acid, and was followed by meta-cleavage to produce 3-(2-formylacenaphthylen-1-yl)-2-hydroxy-prop-2-enoic acid. The fluoranthene pathway converged with the benzo[k]fluoranthene pathway through detection of the three-ring product, 2-formylacenaphthylene-1-carboxylic acid. Production of key downstream metabolites, 1,8-naphthalic anhydride and 1-naphthoic acid from benzo[k]fluoranthene, fluoranthene and acenaphthylene biotransformations provided evidence for a common pathway by strain KK22 for all three PAHs through acenaphthoquinone. Quantitative analysis of benzo[k]fluoranthene biotransformation by strain KK22 confirmed biodegradation. This is the first pathway proposed for the biotransformation of benzo[k]fluoranthene by a bacterium. © 2013 The Authors. Microbial Biotechnology published by John Wiley & Sons Ltd and Society for Applied Microbiology.

  13. Nitrous oxide production in sputum from cystic fibrosis patients with chronic Pseudomonas aeruginosa lung infection

    DEFF Research Database (Denmark)

    Kolpen, Mette; Kühl, Michael; Bjarnsholt, Thomas

    2014-01-01

    local anoxia by consuming the majority of O2 for production of reactive oxygen species (ROS). We hypothesized that P. aeruginosa acquires energy for growth in anaerobic endobronchial mucus by denitrification, which can be demonstrated by production of nitrous oxide (N2O), an intermediate...

  14. Nitrous oxide production, its source and distribution in urine patches on grassland on peat soil.

    NARCIS (Netherlands)

    Koops, J.G.; Beusichem, van M.L.; Oenema, O.

    1997-01-01

    Urine patches are considered to be important sites for nitrous oxide (N2O) production through nitrification and denitrification due to their high concentration of nitrogen (N). The aim of the present study was to determine the microbial source and size of production of N2O in different zones of a

  15. Nitrogen oxides in the combustion products of gas cookers

    Energy Technology Data Exchange (ETDEWEB)

    Benes, M.; Zahourek, J.

    1981-07-01

    The combustion of town gas and natural gas in two types of gas ranges manufactured in Czechoslovakia resulted in measurable amounts of NO/sub x/ in both the combustion products and the surrounding air. In all the cases tested, the amounts of NO/sub x/ given off exceeded levels permitted by current Czech standards. These results indicate that before the widespread use of any new gas ranges, their combustion products should be tested for NO/sub x/.

  16. Arginine de novo and nitric oxide production in disease states

    OpenAIRE

    Luiking, Yvette C.; Ten Have, Gabriella A. M.; Wolfe, Robert R.; Deutz, Nicolaas E. P.

    2012-01-01

    Arginine is derived from dietary protein intake, body protein breakdown, or endogenous de novo arginine production. The latter may be linked to the availability of citrulline, which is the immediate precursor of arginine and limiting factor for de novo arginine production. Arginine metabolism is highly compartmentalized due to the expression of the enzymes involved in arginine metabolism in various organs. A small fraction of arginine enters the NO synthase (NOS) pathway. Tetrahydrobiopterin ...

  17. Hydrogen production by ethanol partial oxidation over nano-iron oxide catalysts produced by chemical vapour synthesis

    Energy Technology Data Exchange (ETDEWEB)

    Ahmed, Wael Ahmed Abou Taleb Sayed

    2011-01-13

    This work presents the experimental results of the synthesis of unsupported and supported SiC iron oxide nanoparticles and their catalytic activity towards ethanol partial oxidation. For comparison, further unsupported iron oxide phases were investigated towards the ethanol partial oxidation. These {gamma}-Fe{sub 2}O{sub 3} and {alpha}/{gamma}-Fe{sub 2}O{sub 3} phase catalysts were prepared by the CVS method using Fe(CO){sub 5} as precursor, supplied by another author. The {alpha}-Fe{sub 2}O{sub 3} and SiC nanoparticles were prepared by the CVS method using a home made hot wall reactor technique at atmospheric pressure. Ferrocene and tetramethylsilane were used as precursor for the production process. Process parameters of precursor evaporation temperature, precursor concentration, gas mixture velocity and gas mixture dilution were investigated and optimised to produce particle sizes in a range of 10 nm. For Fe{sub 2}O{sub 3}/SiC catalyst series production, a new hot wall reactor setup was used. The particles were produced by simultaneous thermal decomposition of ferrocene and tetramethylsilane in one reactor from both sides. The production parameters of inlet tube distance inside the reactor, precursor evaporation temperature and carrier gas flow were investigated to produce a series of samples with different iron oxide content. The prepared catalysts composition, physical and chemical properties were characterized by XRD, EDX, SEM, BET surface area, FTIR, XPS and dynamic light scattering (DLS) techniques. The catalytic activity for the ethanol gas-phase oxidation was investigated in a temperature range from 260 C to 290 C. The product distributions obtained over all catalysts were analysed with mass spectrometry analysis tool. The activity of bulk Fe{sub 2}O{sub 3} and SiC nanoparticles was compared with prepared nano-iron oxide phase catalysts. The reaction parameters, such as reaction temperature and O{sub 2}/ethanol ratio were investigated. The catalysts

  18. Production of petroleum bitumen by oxidation of heavy oil residue with sulfur

    Science.gov (United States)

    Tileuberdi, Ye.; Akkazyn, Ye. A.; Ongarbayev, Ye. K.; Imanbayev, Ye. I.; Mansurov, Z. A.

    2018-03-01

    In this paper production of bitumen adding elemental sulfur at oxidation of oil residue are investigated. The objects of research were distilled residue of Karazhanbas crude oil and elemental sulfur. These oil residue characterized by a low output of easy fractions and the high content of tar-asphaltene substances, therefore is the most comprehensible feedstock for producing bitumen. The sulfur is one of the oil product collected in oil extraction regions. Oxidation process of hydrocarbons carried out at temperatures from 180 up to 210 °С without addition of sulfur and with the addition of sulfur (5-10 wt. %) for 4 hours. At 200 °С oxidation of hydrocarbons with 5, 7 and 10 wt.% sulfur within 3-4 h allows receiving paving bitumen on the mark BND 200/300, BND 130/200, BN 90/130 and BN 70/30. Physical and mechanical characteristics of oxidation products with the addition of 5-7 wt. % sulfur corresponds to grade of paving bitumen BND 40/60. At the given temperature oxidized for 2.5-3 h, addition of 10 wt. % sulfur gave the products of oxidation describing on parameters of construction grades of bitumen (BN 90/10).

  19. Real-time measurements of particulate matter and polycyclic aromatic hydrocarbon emissions from stationary combustion sources used in oil and gas production

    International Nuclear Information System (INIS)

    Hahn, D. W.; Hencken, K. R.; Johnsen, H. A.; Ross, J. R.; Walsh, P. M.

    1998-01-01

    Particulate matter emissions and some components of the particles were measured in the exhaust from combustion equipment used in oil and gas production operations near Bakersfield, California. The combustion sources included a 22.5 MW (electric) turbine generator, a 342-Bhp rich-burn spark ignition engine, and a 50 million Btu/h steam generator, all fired using natural gas. The particle components and measurement techniques were as follows: (1) Calcium, magnesium, sodium, silicon, and iron were measured using laser-induced breakdown spectroscopy (LIBS), (2) particle-bound polycyclic aromatic hydrocarbons (PAH) were detected using the charge produced by photoionization, (3) particles having sizes between 0.1 and 7.5 (micro)m were counted using an instrument based on light scattering, and (4) total particulate matter was measured according to US EPA Method 5. Not all of the methods were applied to all of the sources. Measurements were also made in the ambient air near the combustion air inlets to the units, for comparison with the concentrations in the exhaust, but the inlet and outlet measurements were not done simultaneously. Calcium, sodium, and silicon were found in the exhaust from the steam generator at concentrations similar to those in the ambient air near the inlet to the burner. Sodium and silicon were observed in the engine exhaust at levels a factor of four higher than their concentrations in the air. The principal metal observed in the engine exhaust was calcium, a component of the lubricating oil, at a concentration of 11.6 (micro)g/m 3 . The air entering the gas turbine is filtered, so the average concentrations of metals in the turbine exhaust under steady operating conditions were even lower than in the air. During start-up following a shut-down to wash the turbine, silicon and iron were the major species in the stack, at concentrations of 6.4 and 16.2 (micro)g/m 3 , respectively. A possible source of silicon is the water injected into the turbine

  20. submitter Elemental composition and clustering behaviour of α-pinene oxidation products for different oxidation conditions

    CERN Document Server

    Praplan, A P; Bianchi, F; Rissanen, M P; Ehn, M; Jokinen, T; Junninen, H; Adamov, A; Amorim, A; Dommen, J; Duplissy, J; Hakala, J; Hansel, A; Heinritzi, M; Kangasluoma, J; Kirkby, J; Krapf, M; Kürten, A; Lehtipalo, K; Riccobono, F; Rondo, L; Sarnela, N; Simon, M; Tomé, A; Tröstl, J; Winkler, P M; Williamson, C; Ye, P; Curtius, J; Baltensperger, U; Donahue, N M; Kulmala, M; Worsnop, D R

    2015-01-01

    This study presents the difference between oxidised organic compounds formed by α-pinene oxidation under various conditions in the CLOUD environmental chamber: (1) pure ozonolysis (in the presence of hydrogen as hydroxyl radical (OH) scavenger) and (2) OH oxidation (initiated by nitrous acid (HONO) photolysis by ultraviolet light) in the absence of ozone. We discuss results from three Atmospheric Pressure interface Time-of-Flight (APi-TOF) mass spectrometers measuring simultaneously the composition of naturally charged as well as neutral species (via chemical ionisation with nitrate). Natural chemical ionisation takes place in the CLOUD chamber and organic oxidised compounds form clusters with nitrate, bisulfate, bisulfate/sulfuric acid clusters, ammonium, and dimethylaminium, or get protonated. The results from this study show that this process is selective for various oxidised organic compounds with low molar mass and ions, so that in order to obtain a comprehensive picture of the elemental composition o...

  1. Nitric oxide, human diseases and the herbal products that affect the nitric oxide signalling pathway.

    Science.gov (United States)

    Achike, Francis I; Kwan, Chiu-Yin

    2003-09-01

    1. Nitric oxide (NO) is formed enzymatically from l-arginine in the presence of nitric oxide synthase (NOS). Nitric oxide is generated constitutively in endothelial cells via sheer stress and blood-borne substances. Nitric oxide is also generated constitutively in neuronal cells and serves as a neurotransmitter and neuromodulator in non-adrenergic, non-cholinergic nerve endings. Furthermore, NO can also be formed via enzyme induction in many tissues in the presence of cytokines. 2. The ubiquitous presence of NO in the living body suggests that NO plays an important role in the maintenance of health. Being a free radical with vasodilatory properties, NO exerts dual effects on tissues and cells in various biological systems. At low concentrations, NO can dilate the blood vessels and improve the circulation, but at high concentrations it can cause circulatory shock and induce cell death. Thus, diseases can arise in the presence of the extreme ends of the physiological concentrations of NO. 3. The NO signalling pathway has, in recent years, become a target for new drug development. The high level of flavonoids, catechins, tannins and other polyphenolic compounds present in vegetables, fruits, soy, tea and even red wine (from grapes) is believed to contribute to their beneficial health effects. Some of these compounds induce NO formation from the endothelial cells to improve circulation and some suppress the induction of inducible NOS in inflammation and infection. 4. Many botanical medicinal herbs and drugs derived from these herbs have been shown to have effects on the NO signalling pathway. For example, the saponins from ginseng, ginsenosides, have been shown to relax blood vessels (probably contributing to the antifatigue and blood pressure-lowering effects of ginseng) and corpus cavernosum (thus, for the treatment of men suffering from erectile dysfunction; however, the legendary aphrodisiac effect of ginseng may be an overstatement). Many plant extracts or

  2. Controlled nitric oxide production via O(1D) + N2O reactions for use in oxidation flow reactor studies

    Science.gov (United States)

    Lambe, Andrew; Massoli, Paola; Zhang, Xuan; Canagaratna, Manjula; Nowak, John; Daube, Conner; Yan, Chao; Nie, Wei; Onasch, Timothy; Jayne, John; Kolb, Charles; Davidovits, Paul; Worsnop, Douglas; Brune, William

    2017-06-01

    Oxidation flow reactors that use low-pressure mercury lamps to produce hydroxyl (OH) radicals are an emerging technique for studying the oxidative aging of organic aerosols. Here, ozone (O3) is photolyzed at 254 nm to produce O(1D) radicals, which react with water vapor to produce OH. However, the need to use parts-per-million levels of O3 hinders the ability of oxidation flow reactors to simulate NOx-dependent secondary organic aerosol (SOA) formation pathways. Simple addition of nitric oxide (NO) results in fast conversion of NOx (NO + NO2) to nitric acid (HNO3), making it impossible to sustain NOx at levels that are sufficient to compete with hydroperoxy (HO2) radicals as a sink for organic peroxy (RO2) radicals. We developed a new method that is well suited to the characterization of NOx-dependent SOA formation pathways in oxidation flow reactors. NO and NO2 are produced via the reaction O(1D) + N2O → 2NO, followed by the reaction NO + O3 → NO2 + O2. Laboratory measurements coupled with photochemical model simulations suggest that O(1D) + N2O reactions can be used to systematically vary the relative branching ratio of RO2 + NO reactions relative to RO2 + HO2 and/or RO2 + RO2 reactions over a range of conditions relevant to atmospheric SOA formation. We demonstrate proof of concept using high-resolution time-of-flight chemical ionization mass spectrometer (HR-ToF-CIMS) measurements with nitrate (NO3-) reagent ion to detect gas-phase oxidation products of isoprene and α-pinene previously observed in NOx-influenced environments and in laboratory chamber experiments.

  3. Denitrification: an important pathway for nitrous oxide production in tropical mangrove sediments (Goa, India).

    Science.gov (United States)

    Fernandes, Sheryl Oliveira; Bharathi, P A Loka; Bonin, Patricia C; Michotey, Valérie D

    2010-01-01

    Net nitrous oxide production and denitrification activity were measured in two mangrove ecosystems of Goa, India. The relatively pristine site Tuvem was compared to Divar, which is prone to high nutrient input. Stratified sampling at 2-cm intervals within the 0- to 10-cm depth range showed that N2O production at both the locations decreased with depth. Elevated denitrification activity at Divar resulted in maximum production of up to 1.95 nmol N2O-N g(-1) h(-1) at 2 to 4 cm, which was three times higher than at Tuvem. Detailed investigations to understand the major pathway contributing to N2O production performed at Tuvem showed that incomplete denitrification was responsible for up to 43 to 93% of N2O production. Nitrous oxide production rates closely correlated to nitrite concentration (n = 15; r = -0.47; p production. Nitrous oxide production through nitrification was below detection, affirming that denitrification is the major pathway responsible for production of the greenhouse gas. Net N2O production in these mangrove systems are comparatively higher than those reported from other natural estuarine sediments and therefore warrant mitigation measures.

  4. Production of reduction gases: partial oxidation of hydrocarbons and coal

    Energy Technology Data Exchange (ETDEWEB)

    Tippmer, K

    1976-04-01

    After some general remarks on reduction gas and quality demands, the Texaco process of partial oxidation with scrubbing is dealt with. A comparison of current iron-sponge techniques shows that a heat demand below 3 M kcal/t Fe should be envisaged, which means that heavy fuel oil or coal should be used. The special features of oxygen generation, coal processing, demands made on fuel oil, gasoline, and natural gas, gas generation, soot recovery, hydrogen sulphide-carbon dioxide scrubbing, system Benfield HP process, recycle-carbon dioxide scrubbing, auxiliary steam system, gas preheating, recycle gas cooling and compression, process data and heat balances for natural gas (one-heat system) and heating fuel oil or naphtha (two-heat system) are given.

  5. Production of sized particles of uranium oxides and uranium oxyfluorides

    International Nuclear Information System (INIS)

    Knudsen, I.E.; Randall, C.C.

    1976-01-01

    A process is claimed for converting uranium hexafluoride (UF 6 ) to uranium dioxide (UO 2 ) of a relatively large particle size in a fluidized bed reactor by mixing uranium hexafluoride with a mixture of steam and hydrogen and by preliminary reacting in an ejector gaseous uranium hexafluoride with steam and hydrogen to form a mixture of uranium and oxide and uranium oxyfluoride seed particles of varying sizes, separating the larger particles from the smaller particles in a cyclone separator, recycling the smaller seed particles through the ejector to increase their size, and introducing the larger seed particles from the cyclone separator into a fluidized bed reactor where the seed particles serve as nuclei on which coarser particles of uranium dioxide are formed. 9 claims, 2 drawing figures

  6. Microstructural Analysis of the Oxidation Products of Metallic Alloys According to the HALOX Development

    International Nuclear Information System (INIS)

    De Micco, G.

    2001-01-01

    This publication is a first stage in the development of an oxidation process of the fissile material, from spent nuclear fuel elements of research reactors, containing molybdenum.The oxidation of molybdenum powder with air at elevated temperatures (375-500 o C) has been studied by means of X-ray diffraction and scanning electron microscopy.The results show that the only product was MoO 3 in two different phases: Monoclinic and Orthorhombic.MoO 2 and non-stoichiometric molybdenum oxide such as Mo 4 O 1 1 were not evidenced in any of the Mo oxidation steps. By monitoring the time required for the complete oxidation of Mo at different conditions of temperature and pressure, a rate equation has been determined for the whole process. The activation energy and the pressure and degree of reaction dependence, has been calculated.This values remain constant trough out the complete reaction

  7. Temperature controls oxidative phosphorylation and reactive oxygen species production through uncoupling in rat skeletal muscle mitochondria.

    Science.gov (United States)

    Jarmuszkiewicz, Wieslawa; Woyda-Ploszczyca, Andrzej; Koziel, Agnieszka; Majerczak, Joanna; Zoladz, Jerzy A

    2015-06-01

    Mitochondrial respiratory and phosphorylation activities, mitochondrial uncoupling, and hydrogen peroxide formation were studied in isolated rat skeletal muscle mitochondria during experimentally induced hypothermia (25 °C) and hyperthermia (42 °C) compared to the physiological temperature of resting muscle (35 °C). For nonphosphorylating mitochondria, increasing the temperature from 25 to 42 °C led to a decrease in membrane potential, hydrogen peroxide production, and quinone reduction levels. For phosphorylating mitochondria, no temperature-dependent changes in these mitochondrial functions were observed. However, the efficiency of oxidative phosphorylation decreased, whereas the oxidation and phosphorylation rates and oxidative capacities of the mitochondria increased, with increasing assay temperature. An increase in proton leak, including uncoupling protein-mediated proton leak, was observed with increasing assay temperature, which could explain the reduced oxidative phosphorylation efficiency and reactive oxygen species production. Copyright © 2015 Elsevier Inc. All rights reserved.

  8. Biodiesel Production from Castor Oil by Using Calcium Oxide Derived from Mud Clam Shell

    Directory of Open Access Journals (Sweden)

    S. Ismail

    2016-01-01

    Full Text Available The catalytic potential of calcium oxide synthesized from mud clam shell as a heterogeneous catalyst for biodiesel production was studied. The mud clam shell calcium oxide was characterized using particle size analyzer, Fourier transform infrared spectroscopy, scanning electron microscopy, and BET gas sorption analyzer. The catalyst performance of mud clam shell calcium oxide was studied in the transesterification of castor oil as biodiesel. Catalyst characterization and transesterification study results of synthesized catalyst proved the efficiency of the natural derived catalyst for biodiesel production. A highest biodiesel yield of 96.7% was obtained at optimal parameters such as 1 : 14 oil-to-methanol molar ratio, 3% w/w catalyst concentration, 60°C reaction temperature, and 2-hour reaction time. Catalyst reusability test shows that the synthesized calcium oxide from mud clam shell is reusable up to 5 times.

  9. Oxidation of ciprofloxacin and enrofloxacin by ferrate(VI): Products identification, and toxicity evaluation

    International Nuclear Information System (INIS)

    Yang, Bin; Kookana, Rai S.; Williams, Mike; Ying, Guang-Guo; Du, Jun; Doan, Hai; Kumar, Anupama

    2016-01-01

    Ferrate(VI) (Fe(VI)) has been known to react with emerging organic contaminants containing electron-rich organic moieties, such as phenols, anilines, olefins, reduced sulfur and deprotonated amines. Oxidation of fluoroquinolone antibiotics, ciprofloxacin (CIP) and enrofloxacin (ENR), by Fe(VI) were investigated for their reaction products and toxicity changes as well as biodegradability of these products. Ten products were identified for both CIP and ENR reactions with Fe(VI) using a high-resolution accurate-mass Orbitrap mass analyzer. Structural changes to the CIP and ENR molecule included dealkylation, formation of alcohols and amides in piperazine ring and oxygen transfer to the double bond in quinolone structure. An enamine formation mechanism was tentatively proposed to facilitate the interpretation of CIP and ENR oxidation pathways. Toxicity evaluation using Microbial Assay for toxicity Risk Assessment (MARA) bioassay indicated that Fe(VI) oxidation products of CIP and ENR contributed negligible antibacterial potency and Fe(VI) oxidation treatment can remove the residual toxicity of CIP and ENR impacted source waters. The Fe(VI) oxidation treatment resulted in formation of relatively more biodegradable products (based on in silico assessment) than their corresponding parent compounds. The results showed that Fe(VI) has a good potential to degrade fluoroquinolone antibiotics and their antimicrobial potency in natural waters.

  10. Oxidation of ciprofloxacin and enrofloxacin by ferrate(VI): Products identification, and toxicity evaluation

    Energy Technology Data Exchange (ETDEWEB)

    Yang, Bin, E-mail: Bin.Yang@csiro.au [CSIRO Land and Water, Waite Campus, PMB 2, Glen Osmond, South Australia 5064 (Australia); Kookana, Rai S.; Williams, Mike [CSIRO Land and Water, Waite Campus, PMB 2, Glen Osmond, South Australia 5064 (Australia); Ying, Guang-Guo [State Key Laboratory of Organic Geochemistry, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou 510640 (China); Du, Jun; Doan, Hai; Kumar, Anupama [CSIRO Land and Water, Waite Campus, PMB 2, Glen Osmond, South Australia 5064 (Australia)

    2016-12-15

    Ferrate(VI) (Fe(VI)) has been known to react with emerging organic contaminants containing electron-rich organic moieties, such as phenols, anilines, olefins, reduced sulfur and deprotonated amines. Oxidation of fluoroquinolone antibiotics, ciprofloxacin (CIP) and enrofloxacin (ENR), by Fe(VI) were investigated for their reaction products and toxicity changes as well as biodegradability of these products. Ten products were identified for both CIP and ENR reactions with Fe(VI) using a high-resolution accurate-mass Orbitrap mass analyzer. Structural changes to the CIP and ENR molecule included dealkylation, formation of alcohols and amides in piperazine ring and oxygen transfer to the double bond in quinolone structure. An enamine formation mechanism was tentatively proposed to facilitate the interpretation of CIP and ENR oxidation pathways. Toxicity evaluation using Microbial Assay for toxicity Risk Assessment (MARA) bioassay indicated that Fe(VI) oxidation products of CIP and ENR contributed negligible antibacterial potency and Fe(VI) oxidation treatment can remove the residual toxicity of CIP and ENR impacted source waters. The Fe(VI) oxidation treatment resulted in formation of relatively more biodegradable products (based on in silico assessment) than their corresponding parent compounds. The results showed that Fe(VI) has a good potential to degrade fluoroquinolone antibiotics and their antimicrobial potency in natural waters.

  11. Searching for new sources of innovative products for the food industry within halophyte aromatic plants: In vitro antioxidant activity and phenolic and mineral contents of infusions and decoctions of Crithmum maritimum L.

    Science.gov (United States)

    Pereira, Catarina Guerreiro; Barreira, Luísa; da Rosa Neng, Nuno; Nogueira, José Manuel Florêncio; Marques, Cátia; Santos, Tamára F; Varela, João; Custódio, Luísa

    2017-09-01

    Aromatic halophyte plants are an outstanding source of bioactive compounds and natural products with potential use in the food industry. This work reports the in vitro antioxidant activity, toxicity, polyphenolic profile and mineral contents of infusions and decoctions from stems, leaves and flowers of Crithmum maritimum L., an aromatic and edible maritime halophyte (sea fennel). Aspalathus linearis (Burm.f.) Dahlg. (rooibos) herbal tea was used as a reference. Sea fennel's tisanes, particularly from leaves, were rich in phenolic compounds and five of them (p-hydroxybenzoic and ferulic acids, epicatechin, pyrocatechol and 4-hydroxybenzaldehyde) were here described in C. maritimum for the first time. Chlorogenic acid was the dominant phenolic determined. Na was the most abundant mineral in all tisanes followed by Ca and Mg in leaves' tisanes and K in flowers. Sea fennel's samples had a similar antioxidant activity than those from A. linearis, and had no significant toxicity towards four different mammalian cell lines. Altogether, our results suggest that sea fennel can be a source of products and/or molecules for the food industry with antioxidant properties and minerals in the form, for example, of innovative health-promoting herbal beverages. Copyright © 2017 Elsevier Ltd. All rights reserved.

  12. Nitrous Oxide Production in a Granule-based Partial Nitritation Reactor: A Model-based Evaluation.

    Science.gov (United States)

    Peng, Lai; Sun, Jing; Liu, Yiwen; Dai, Xiaohu; Ni, Bing-Jie

    2017-04-03

    Sustainable wastewater treatment has been attracting increasing attentions over the past decades. However, the production of nitrous oxide (N 2 O), a potent GHG, from the energy-efficient granule-based autotrophic nitrogen removal is largely unknown. This study applied a previously established N 2 O model, which incorporated two N 2 O production pathways by ammonia-oxidizing bacteria (AOB) (AOB denitrification and the hydroxylamine (NH 2 OH) oxidation). The two-pathway model was used to describe N 2 O production from a granule-based partial nitritation (PN) reactor and provide insights into the N 2 O distribution inside granules. The model was evaluated by comparing simulation results with N 2 O monitoring profiles as well as isotopic measurement data from the PN reactor. The model demonstrated its good predictive ability against N 2 O dynamics and provided useful information about the shift of N 2 O production pathways inside granules for the first time. The simulation results indicated that the increase of oxygen concentration and granule size would significantly enhance N 2 O production. The results further revealed a linear relationship between N 2 O production and ammonia oxidation rate (AOR) (R 2  = 0.99) under the conditions of varying oxygen levels and granule diameters, suggesting that bulk oxygen and granule size may exert an indirect effect on N 2 O production by causing a change in AOR.

  13. Thermal Oxidation of Tail Gases from the Production of Oil-furnace Carbon Black

    Directory of Open Access Journals (Sweden)

    Bosak, Z.

    2009-01-01

    Full Text Available This paper describes the production technology of oil-furnace carbon black, as well as the selected solution for preventing the emissions of this process from contaminating the environment.The products of industrial oil-furnace carbon black production are different grades of carbon black and process tail gases. The qualitative composition of these tail gases during the production of oil-furnace carbon black are: carbon(IV oxide, carbon(II oxide, hydrogen, methane, hydrogen sulfide, nitrogen, oxygen, and water vapor.The quantitative composition and lower caloric value of process tail gases change depending on the type of feedstock used in the production, as well as the type of process. The lower caloric value of process tail gases is relatively small with values ranging between 1500 and 2300 kJ m–3.In the conventional production of oil-furnace carbon black, process tail gases purified from carbon black dust are freely released into the atmosphere untreated. In this manner, the process tail gases pollute the air in the town of Kutina, because their quantitative values are much higher than the prescribed emissions limits for hydrogen sulfide and carbon(II oxide. A logical solution for the prevention of such air pollution is combustion of the process tail gases, i. e. their thermal oxidation. For this purpose, a specially designed flare system has been developed. Consuming minimum amounts of natural gas needed for oxidation, the flare system is designed to combust low caloric process tail gases with 99 % efficiency. Thus, the toxic and flammable components of the tail gases (hydrogen sulfide, hydrogen, carbon(II oxide, methane and other trace hydrocarbons would be transformed into environmentally acceptable components (sulfur(IV oxide, water, carbon(IV oxide and nitrogen(IV oxide, which are in compliance with the emissions limit values prescribed by law.Proper operation of this flare system in the production of oil-furnace carbon black would solve

  14. Substituted Phthalic Anhydrides from Biobased Furanics : A New Approach to Renewable Aromatics

    NARCIS (Netherlands)

    Thiyagarajan, Shanmugam; Genuino, Homer C.|info:eu-repo/dai/nl/371571685; Sliwa, Michal; van der Waal, Jan C.; de Jong, Ed; van Haveren, Jacco; Weckhuysen, Bert M.|info:eu-repo/dai/nl/285484397; Bruijnincx, Pieter C. A.|info:eu-repo/dai/nl/33799529X; van Es, Daan S.

    2015-01-01

    A novel route for the production of renewable aromatic chemicals, particularly substituted phthalic acid anhydrides, is presented. The classical two-step approach to furanics-derived aromatics via Diels-Alder (DA) aromatization has been modified into a three-step procedure to address the general

  15. Production of nitrous oxide in the auroral D and E regions

    Science.gov (United States)

    Zipf, E. C.; Prasad, S. S.

    1980-01-01

    A study of nitrous oxide formation mechanisms indicates that N2O concentrations greater than 10 to the 9th per cu cm could be produced in IBC III aurora or by lower-level activity lasting for many hours, and, in favorable conditions, the N2O concentration could exceed the local nitric oxide density. An upper limit on the globally averaged N2O production rate from auroral activity is estimated at 2 x 10 to the 27th per second.

  16. Field study of nitrous oxide production with in situ aeration in a closed landfill site.

    Science.gov (United States)

    Nag, Mitali; Shimaoka, Takayuki; Nakayama, Hirofumi; Komiya, Teppei; Xiaoli, Chai

    2016-03-01

    Nitrous oxide (N(2)O) has gained considerable attention as a contributor to global warming and depilation of stratospheric ozone layer. Landfill is one of the high emitters of greenhouse gas such as methane and N(2)O during the biodegradation of solid waste. Landfill aeration has been attracted increasing attention worldwide for fast, controlled and sustainable conversion of landfills into a biological stabilized condition, however landfill aeration impel N(2)O emission with ammonia removal. N(2)O originates from the biodegradation, or the combustion of nitrogen-containing solid waste during the microbial process of nitrification and denitrification. During these two processes, formation of N(2)O as a by-product from nitrification, or as an intermediate product of denitrification. In this study, air was injected into a closed landfill site and investigated the major N(2)O production factors and correlations established between them. The in-situ aeration experiment was carried out by three sets of gas collection pipes along with temperature probes were installed at three different distances of one, two and three meter away from the aeration point; named points A-C, respectively. Each set of pipes consisted of three different pipes at three different depths of 0.0, 0.75 and 1.5 m from the bottom of the cover soil. Landfill gases composition was monitored weekly and gas samples were collected for analysis of nitrous oxide concentrations. It was evaluated that temperatures within the range of 30-40°C with high oxygen content led to higher generation of nitrous oxide with high aeration rate. Lower O(2) content can infuse N(2)O production during nitrification and high O(2) inhibit denitrification which would affect N(2)O production. The findings provide insights concerning the production potentials of N(2)O in an aerated landfill that may help to minimize with appropriate control of the operational parameters and biological reactions of N turnover. Investigation of

  17. Processing of atmospheric polycyclic aromatic hydrocarbons by fog in an urban environment.

    Science.gov (United States)

    Ehrenhauser, Franz S; Khadapkar, Kalindi; Wang, Youliang; Hutchings, James W; Delhomme, Olivier; Kommalapati, Raghava R; Herckes, Pierre; Wornat, Mary J; Valsaraj, Kalliat T

    2012-10-26

    Polycyclic aromatic hydrocarbons (PAH) are ubiquitous pollutants in the atmosphere, predominantly known for their toxicity. Although there has been substantial work on the atmospheric degradation of PAH, little is known about how the presence of atmospheric droplets (e.g., a fog cloud) affects the fate of PAH. In order to assess the processing of PAH and their corresponding oxidation products during a fog event, two field-sampling campaigns in Fresno, CA and Davis, CA were conducted. The simultaneous evaluation of concentrations of the PAH and oxygenated polycyclic aromatic compounds (OPAC) in the gas phase, particulate matter and fog water droplets before, during and after fog allows for the characterization of transformative and transport processes in a fog cloud. By tracking the ratio of OPAC to PAH in the individual atmospheric phases, two major polycyclic aromatic compounds-processing pathways can be identified: (i) the dissolution of OPAC from particulate matter and (ii) the uptake and oxidation of PAH in the fog water droplets. Wet deposition steadily decreases the pollutant concentration in the fog cloud droplets during a fog event; however, uptake and concentration via evaporative water loss upon the dissipation of a fog cloud cause an increase in the atmospheric pollutant concentration.

  18. Inhibitory effect on nitric oxide production and free radical scavenging activity of Thai medicinal plants in osteoarthritic knee treatment.

    Science.gov (United States)

    Anuthakoengkun, Areeya; Itharat, Arunporn

    2014-08-01

    Thai medicine plants used for Osteoarthritis of knee (OA) treatment consist of twelve plants such as Crinumn asiaticum, Cleome viscosa, Drypetes roxburghii, Piper longum, Piper nigrum, Plumbago indica, Alpinia galanga, Curcuma aromatica, Globba malaccensis, Zingiber montanum, Zingiber officinale andZingiberzerumbet. They showedhighfrequency in OA formula. To investigate inhibitory effect on LPS-induced nitric oxide (NO) release from RAW264. 7 cell and free radical scavenging activity usingDPPH assay of these ethanolic plant extracts. Plant materials were extracted by maceration in 95% ethanol. Anti-inflammatory activity were tested on LPS-induced NO production. Free radical scavenging activity was performed by DPPH assay. All of ethanolic extracts exhibited potent inhibitory effect on NO release. The ethanolic extract of Z. zerumbet exhibited the highest inhibitory effect followed by Z. montanum and G. malaccensis, respectively. Except A. galanga and C. viscosa, all extracts possessed more influential than indomethacin (IC50 = 20.32±3.23 μLg/ml), a positive control. The investigation on antioxidant activity suggested that the ethanolic extracts of D. roxburghii, Z. officinale, Z. montanum, C. aromatic, A. galanga, P indica, G malaccensis, P nigrum exhibited antioxidant activity. By means ofD. roxburghii had the highest electron donating activity,followed by Z. officinale. Moreover both extracts were more effective than BHT apositive control (EC50 = 14.04±1.95 μg/ml). Thai medicinal plants had anti-inflammatory activity and could inhibit destruction of articular cartilage that corresponded to the traditional medicine and supported using these medicinal plants for OA treatment.

  19. Nitric oxide production by rat bronchoalveolar macrophages or ...

    Indian Academy of Sciences (India)

    Unknown

    inflammatory responses to either LPS or silica. For in- stance, the capacity of AMs to respond directly to LPS with increases in NO production has been well docu- mented (Jorens et al 1991; Warner et al 1995). AMs also are a likely source of the NO produced following silica exposure (Huffman et al 1998; Porter et al 2002).

  20. Nitric oxide production by rat bronchoalveolar macrophages or ...

    Indian Academy of Sciences (India)

    Unknown

    Media levels of nitrate and nitrite (NOx; the stable decomposition products of NO) ... have the capacity to express iNOS mRNA and produce. NO, much of ... Sil, < 5 µm diameter, US Silica Corp., Berkeley Springs, ..... provides new information.

  1. Variation in excess oxidant factor in combustion products of MHD generator. [Natural gas fuel

    Energy Technology Data Exchange (ETDEWEB)

    Pinkhasik, M S; Mironov, V D; Zakharko, Yu A; Plavinskii, A I

    1977-12-01

    Methods and difficulties associated with determining the excess oxidant factor for natural gas-fired MHD generators are discussed. The measurement of this factor is noted to be essential for the optimization of the combustion chamber and operation of MHD generators. A gas analyzer of electrochemical type is considered as a quick - response sensor capable of analyzing the composition of the combustion products and thus determining accurately the excess oxidant factor. The principle of operation of this sensor is discussed and the dependence of the electrochemical sensor emf on excess oxidant factor is shown. Three types of sensors are illustrated and tables of test results are provided.

  2. Oxidized lipids enhance RANKL production by T lymphocytes: implications for lipid-induced bone loss.

    Science.gov (United States)

    Graham, Lucia S; Parhami, Farhad; Tintut, Yin; Kitchen, Christina M R; Demer, Linda L; Effros, Rita B

    2009-11-01

    Osteoporosis is a systemic disease that is associated with increased morbidity, mortality and health care costs. Whereas osteoclasts and osteoblasts are the main regulators of bone homeostasis, recent studies underscore a key role for the immune system, particularly via activation-induced T lymphocyte production of receptor activator of NFkappaB ligand (RANKL). Well-documented as a mediator of T lymphocyte/dendritic cell interactions, RANKL also stimulates the maturation and activation of bone-resorbing osteoclasts. Given that lipid oxidation products mediate inflammatory and metabolic disorders such as osteoporosis and atherosclerosis, and since oxidized lipids affect several T lymphocyte functions, we hypothesized that RANKL production might also be subject to modulation by oxidized lipids. Here, we show that short term exposure of both unstimulated and activated human T lymphocytes to minimally oxidized low density lipoprotein (LDL), but not native LDL, significantly enhances RANKL production and promotes expression of the lectin-like oxidized LDL receptor-1 (LOX-1). The effect, which is also observed with 8-iso-Prostaglandin E2, an inflammatory isoprostane produced by lipid peroxidation, is mediated via the NFkappaB pathway, and involves increased RANKL mRNA expression. The link between oxidized lipids and T lymphocytes is further reinforced by analysis of hyperlipidemic mice, in which bone loss is associated with increased RANKL mRNA in T lymphocytes and elevated RANKL serum levels. Our results suggest a novel pathway by which T lymphocytes contribute to bone changes, namely, via oxidized lipid enhancement of RANKL production. These findings may help elucidate clinical associations between cardiovascular disease and decreased bone mass, and may also lead to new immune-based approaches to osteoporosis.

  3. Nitrous oxide production pathways in a partial nitritation-anammox reactor: Isotopic evidence for nitrous oxide production associated anaerobic ammonium oxidation?

    Science.gov (United States)

    Wunderlin, P.; Harris, E. J.; Joss, A.; Emmenegger, L.; Kipf, M.; Mohn, J.; Siegrist, H.

    2014-12-01

    Nitrous oxide (N2O) is a strong greenhouse gas and a major sink for stratospheric ozone. In biological wastewater treatment N2O can be produced via several pathways. This study investigates the dynamics of N2O emissions from a nitritation-anammox reactor, and links its interpretation to the nitrogen and oxygen isotopic signature of the emitted N2O. A 400-litre single-stage nitritation-anammox reactor was operated and continuously fed with digester liquid. The isotopic composition of N2O emissions was monitored online with quantum cascade laser absorption spectroscopy (QCLAS; Aerodyne Research, Inc.; Waechter et al., 2008). Dissolved ammonium and nitrate were monitored online (ISEmax, Endress + Hauser), while nitrite was measured with test strips (Nitrite-test 0-24mgN/l, Merck). Table 1. Summary of experiments conducted to understand N2O emissions Experimental conditions O2[mgO2/L] NO2-[mgN/L] NH4+[mgN/L] N2O/NH4+[%] Normal operation production pathway, which is hypothesized to be mediated by anammox activity (Figure 1). A less likely explanation is that the SP of N2O was increased by partial N2O reduction by heterotrophic denitrification. Various experiments were conducted to further investigate N2O formation pathways in the reactor. Our data reveal that N2O emissions increased when reactor operation was not ideal, for example when dissolved oxygen was too high (Table 1). SP measurements confirmed that these N2O peaks were due to enhanced nitrifier denitrification, generally related to nitrite build-up in the reactor (Figure 1; Table 1). Overall, process control via online N2O monitoring was confirmed to be an ideal method to detect imbalances in reactor operation and regulate aeration, to ensure optimal reactor conditions and minimise N2O emissions. ReferencesWaechter H. et al. (2008) Optics Express, 16: 9239-9244. Wunderlin, P et al. (2013) Environmental Science & Technology 47: 1339-1348.

  4. Aromatic Polyketide GTRI-02 is a Previously Unidentified Product of the act Gene Cluster in Streptomyces coelicolor A3(2).

    Science.gov (United States)

    Wu, Changsheng; Ichinose, Koji; Choi, Young Hae; van Wezel, Gilles P

    2017-07-18

    The biosynthesis of aromatic polyketides derived from type II polyketide synthases (PKSs) is complex, and it is not uncommon that highly similar gene clusters give rise to diverse structural architectures. The act biosynthetic gene cluster (BGC) of the model actinomycete Streptomyces coelicolor A3(2) is an archetypal type II PKS. Here we show that the act BGC also specifies the aromatic polyketide GTRI-02 (1) and propose a mechanism for the biogenesis of its 3,4-dihydronaphthalen-1(2H)-one backbone. Polyketide 1 was also produced by Streptomyces sp. MBT76 after activation of the act-like qin gene cluster by overexpression of the pathway-specific activator. Mining of this strain also identified dehydroxy-GTRI-02 (2), which most likely originated from dehydration of 1 during the isolation process. This work shows that even extensively studied model gene clusters such as act of S. coelicolor can still produce new chemistry, offering new perspectives for drug discovery. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  5. Secondary organic aerosol formation through cloud processing of aromatic VOCs

    Science.gov (United States)

    Herckes, P.; Hutchings, J. W.; Ervens, B.

    2010-12-01

    Field observations have shown substantial concentrations (20-5,500 ng L-1) of aromatic volatile organic compounds (VOC) in cloud droplets. The potential generation of secondary organic aerosol mass through the processing of these anthropogenic VOCs was investigated through laboratory and modeling studies. Under simulated atmospheric laboratory conditions, in idealized solutions, benzene, toluene, ethylbenzene, and xylene (BTEX) degraded quickly in the aqueous phase. The degradation process yielded less volatile products which would contribute to new aerosol mass upon cloud evaporation. However, when realistic cloud solutions containing natural organic matter were used in the experiments, the reaction rates decreased with increasing organic carbon content. Kinetic data derived from these experiments were used as input to a multiphase box model in order to evaluate the secondary organic aerosol (SOA) mass formation potential of cloud processing of BTEX. Model results will be presented that quantify the SOA amounts from these aqueous phase pathways. The efficiency of this multiphase SOA source will be compared to SOA yields from the same aromatics as treated in traditional SOA models that are restricted to gas phase oxidation and subsequent condensation on particles.

  6. Synthesis and bioelectrochemical behavior of aromatic amines.

    Science.gov (United States)

    Shabbir, Muhammad; Akhter, Zareen; Ahmad, Iqbal; Ahmed, Safeer; Bolte, Michael; McKee, Vickie

    2017-12-01

    Four aromatic amines 1-amino-4-phenoxybenzene (A 1 ), 4-(4-aminophenyloxy) biphenyl (A 2 ), 1-(4-aminophenoxy) naphthalene (A 3 ) and 2-(4-aminophenoxy) naphthalene (A 4 ) were synthesized and characterized by elemental, spectroscopic (FTIR, NMR), mass spectrometric and single crystal X-ray diffraction methods. The compounds crystallized in monoclinic crystal system with space group P2 1 . Intermolecular hydrogen bonds were observed between the amine group and amine/ether acceptors of neighboring molecules. Electrochemical investigations were done using cyclic voltammetry (CV), square wave voltammetry (SWV) and differential pulse voltammetry (DPV). CV studies showed that oxidation of aromatic amines takes place at about 0.9 V (vs. Ag/AgCl) and the electron transfer (ET) process has irreversible nature. After first scan reactive intermediate were generated electrochemically and some other cathodic and anodic peaks also appeared in the succeeding scans. DPV study revealed that ET process is accompanied by one electron. DNA binding study of aromatic amines was performed by CV and UV-visible spectroscopy. These investigations revealed groove binding mode of interaction of aromatic amines with DNA. Copyright © 2017 Elsevier Inc. All rights reserved.

  7. Ru(II)-Catalyzed Oxidative Heck-Type Olefination of Aromatic Carboxylic Acids with Styrenes through Carboxylate-Assisted C-H Bond Activation.

    Science.gov (United States)

    Dana, Suman; Mandal, Anup; Sahoo, Harekrishna; Mallik, Sumitava; Grandhi, Gowri Sankar; Baidya, Mahiuddin

    2018-02-02

    A straightforward synthesis of 2-styrylbenzoic acids from aryl carboxylic acids is disclosed through a carboxylate-assisted coupling under Ru(II) catalysis. This protocol is simple and exhibits broad scope with high tolerance of common organic functional groups, providing good to excellent yields of diverse olefinated products. The efficacy of this protocol has been showcased through sequential syntheses of isochromanone, isocoumarin, and formal synthesis of anacardic acid derivative in good yields.

  8. High production volume chemical Amine Oxide [C8-C20] category environmental risk assessment

    DEFF Research Database (Denmark)

    Sanderson, Hans; Tibazarwa, Caritas; Greggs, William

    2009-01-01

    and personal care products. Given the lack of persistence or bioaccumulation, and the low likelihood of these chemicals partitioning to soil, the focus of the environmental assessment is on the aquatic environment. In the United States, the E-FAST model is used to estimate effluent concentrations in the United......An environmental assessment of amine oxides has been conducted under the OECD SIDS High Production Volume (HPV) Program via the Global International Council of Chemical Associations (ICCA) Amine Oxides Consortium. Amine oxides are primarily used in conjunction with surfactants in cleaning...... States from manufacturing facilities and from municipal facilities resulting from consumer product uses. Reasonable worst-case ratios of predicted environmental concentration (PEC) to predicted no effect concentration (PNEC) range from 0.04 to 0.003, demonstrating that these chemicals are a low risk...

  9. Nano tubular Transition Metal Oxide for Hydrogen Production

    International Nuclear Information System (INIS)

    Sreekantan, S.; San, E.P.; Kregvirat, W.; Wei, L.C.

    2011-01-01

    TiO 2 , transition metal oxide nano tubes were successfully grown by anodizing of titanium foil (Ti) in ethylene glycol electrolyte containing 5wt. % hydrogen peroxide and 5wt. % ammonium fluoride for 60 minutes at 60V. It was found such electrochemical condition resulted in the formation of nano tube with average diameter of 90nm and length of 6.6 μm. These samples were used to study the effect of W loading by RF sputtering on TiO 2 nano tubes. Amorphous TiO 2 nano tube substrate leads to enhance incorporation of W instead of anatase. Therefore for the entire study, W was sputtered on amorphous TiO 2 nano tube substrate. TiO 2 nano tube sputtered for 1 minute resulted in the formation of W-O-Ti while beyond this point (10 minutes); it accumulates to form a self independent structure of WO 3 on the surface of the nano tubes. TiO 2 nano tube sputtered for 1 minute at 150 W and annealed at 450 degree Celsius exhibited best photocurrent density (1.4 mA/ cm 2 ) with photo conversion efficiency of 2.5 %. The reason for such behavior is attributed to W 6+ ions allows for electron traps that suppress electron hole recombination and exploit the lower band gap of material to produce a water splitting process by increasing the charge separation and extending the energy range of photoexcitation for the system. (author)

  10. MIS High-Purity Plutonium Oxide Metal Oxidation Product TS707001 (SSR123): Final Report

    Energy Technology Data Exchange (ETDEWEB)

    Veirs, Douglas Kirk [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Stroud, Mary Ann [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Berg, John M. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Narlesky, Joshua Edward [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Worl, Laura Ann [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Martinez, Max A. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Carillo, Alex [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2017-08-09

    A high-purity plutonium dioxide material from the Material Identification and Surveillance (MIS) Program inventory has been studied with regard to gas generation and corrosion in a storage environment. Sample TS707001 represents process plutonium oxides from several metal oxidation operations as well as impure and scrap plutonium from Hanford that are currently stored in 3013 containers. After calcination to 950°C, the material contained 86.98% plutonium with no major impurities. This study followed over time, the gas pressure of a sample with nominally 0.5 wt% water in a sealed container with an internal volume scaled to 1/500th of the volume of a 3013 container. Gas compositions were measured periodically over a six year period. The maximum observed gas pressure was 138 kPa. The increase over the initial pressure of 80 kPa was primarily due to generation of nitrogen and carbon dioxide gas in the first six months. Hydrogen and oxygen were minor components of the headspace gas. At the completion of the study, the internal components of the sealed container showed signs of corrosion, including pitting.

  11. Enhancing lipid productivity of Chlorella vulgaris using oxidative stress by TiO2 nanoparticles

    International Nuclear Information System (INIS)

    Kang, Nam Kyu; Lee, Bongsoo; Choi, Gang-Guk; Moon, Myounghoon; Park, Min S.; Yang, Ji-Won; Lim, JitKang

    2014-01-01

    Ability to increase the lipid production in microalgae is one of the heavily sought-after ideas to improve the economic feasibility of microalgae-derived transportation fuels for commercial applications. We used the oxidative stress by TiO 2 nanoparticles, a well-known photocatalyst, to induce lipid production in microalgae. Chlorella vulgaris UTEX 265 was cultivated under various concentrations of TiO 2 ranging from 0.1 to 5 g/L under UV-A illumination. Maximum specific growth rate was affected in responding to TiO 2 concentrations. In the presence of UV-A, chlorophyll concentration was decreased at the highest concentration of TiO 2 (5 g/L TiO 2 ) by oxidative stress. The fatty acid methyl ester (FAME) composition analysis suggested that oxidative stress causes the accumulation and decomposition of lipids. The highest FAME productivity was 18.2 g/L/d under low concentrations of TiO 2 (0.1 g/L) and a short induction time (two days). The controlled condition of TiO 2 /UV-A inducing oxidative stress (0.1 g/L TiO 2 and two days induction) could be used to increase the lipid productivity of C. vulgaris UTEX 265. Our results show the possibility of modulating the lipid induction process through oxidative stress with TiO 2 /UV-A

  12. Enhancing lipid productivity of Chlorella vulgaris using oxidative stress by TiO{sub 2} nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Kang, Nam Kyu; Lee, Bongsoo; Choi, Gang-Guk; Moon, Myounghoon; Park, Min S.; Yang, Ji-Won [Daejeon, Daejeon (Korea, Republic of); Lim, JitKang [Universiti Sains Malaysia, Penang (Malaysia)

    2014-05-15

    Ability to increase the lipid production in microalgae is one of the heavily sought-after ideas to improve the economic feasibility of microalgae-derived transportation fuels for commercial applications. We used the oxidative stress by TiO{sub 2} nanoparticles, a well-known photocatalyst, to induce lipid production in microalgae. Chlorella vulgaris UTEX 265 was cultivated under various concentrations of TiO{sub 2} ranging from 0.1 to 5 g/L under UV-A illumination. Maximum specific growth rate was affected in responding to TiO{sub 2} concentrations. In the presence of UV-A, chlorophyll concentration was decreased at the highest concentration of TiO{sub 2} (5 g/L TiO{sub 2}) by oxidative stress. The fatty acid methyl ester (FAME) composition analysis suggested that oxidative stress causes the accumulation and decomposition of lipids. The highest FAME productivity was 18.2 g/L/d under low concentrations of TiO{sub 2} (0.1 g/L) and a short induction time (two days). The controlled condition of TiO{sub 2}/UV-A inducing oxidative stress (0.1 g/L TiO{sub 2} and two days induction) could be used to increase the lipid productivity of C. vulgaris UTEX 265. Our results show the possibility of modulating the lipid induction process through oxidative stress with TiO{sub 2}/UV-A.

  13. Serum Antioxidative Enzymes Levels and Oxidative Stress Products in Age-Related Cataract Patients

    Directory of Open Access Journals (Sweden)

    Dong Chang

    2013-01-01

    Full Text Available Purpose. To investigate the activity of antioxidative enzymes and the products of oxidative stress in patients with age-related cataracts and compare the findings with those in healthy control subjects. Method. Sixty patients with age-related cataract and sixty healthy controls of matched age and gender were included in this study. Serum samples were obtained to detect the antioxidative enzymes of superoxide dismutase (SOD, catalase (CAT, and glutathione peroxidase (GSH-Px, and oxidation degradation products of malondialdehyde (MDA, 4-hydroxynonenal (4-HNE, conjugated diene (CD, advanced oxidation protein products (AOPP, protein carbonyl (PC, and 8-hydroxydeoxyguanosine (8-OHdG. Results. Serum SOD, GSH-Px, and CAT activities in cataract group were significantly decreased as compared to the control subjects (P<0.05. The levels of MDA, 4-HNE, and CD in cataract patients were significantly higher than those in the control subjects (P<0.05, P<0.01. Cataract patients had higher levels of 8-OHdG, AOPP, and PC with respect to the comparative group of normal subjects (P<0.01. And there was no statistical significance in concentration of antioxidative enzymes and oxidative stress products in patients with different subtype cataract. Conclusions. Oxidative stress is an important risk factor in the development of age-related cataract, and augmentation of the antioxidant defence systems may be of benefit to prevent or delay cataractogenesis.

  14. Lipid and cholesterol oxidation, color changes, and volatile compounds production in irradiated raw pork batters with different fat content

    International Nuclear Information System (INIS)

    Jo, Cheo Run; Byun, Myung Woo

    2000-01-01

    An emulsion-type product was prepared to determine the effect of irradiation on lipid and cholesterol oxidation, color change, and volatile production in raw pork with different fat content. Lipid oxidation increased with an increase in fat content or irradiation dose. Irradiated batters had higher cholesterol oxides than did non-irradiated batters, and the major cholesterol oxides formed in irradiated pork batters were 7α- and 7β- hydroxycholesterol. Hunter color a- and b-values of raw pork batters were decreased by irradiation regardless of fat content. Irradiation significantly increased the amount of volatile compounds. Although lipid oxidation of high fat products (10 and 15% fat) was higher than that of low fat products (4%), high fat products did not always produce greater amount of volatile compounds in raw pork batters. In summary, irradiation increased lipid and cholesterol oxidation, and volatile compounds production, and had detrimental effects on the color of raw pork batter under aerobic conditions

  15. Biodiesel production using calcium manganese oxide as catalyst and different raw materials

    International Nuclear Information System (INIS)

    Dias, Joana Maia; Conceição Machado Alvim-Ferraz, Maria; Fonseca Almeida, Manuel; Méndez Díaz, José Diego; Sánchez Polo, Manuel; Rivera Utrilla, José

    2013-01-01

    Highlights: ► Biodiesel production using a calcium manganese oxide catalyst was studied. ► The active specie was Ca 0.9 Mn 0.1 O and its deactivation occurred by hydration. ► The studied catalyst presented lower activation temperature than CaO. ► Biodiesel production and quality using different raw materials is reported. ► Compared to the conventional process, biodiesel water content improved. - Abstract: The use of heterogeneous catalysts for biodiesel production aims to simplify the production process as well as to reduce purification costs and related environmental impacts. Calcium manganese oxide was recently identified by the authors as an interesting heterogeneous catalyst for biodiesel production from animal fat; however, the difference between this and other catalysts, the catalyst activation/deactivation mechanisms, its behaviour in the synthesis using different raw materials as well as the impacts of its use on product quality remained unclear. Therefore, the present work: (i) compared biodiesel production using calcium manganese oxide and other catalysts (CaO and NaOH); (ii) studied the reasons leading to activation/deactivation of the heterogeneous catalyst; (iii) analysed biodiesel heterogeneous synthesis using calcium manganese oxide and different raw materials (lard, waste frying oil and a mixture); and (iv) evaluated raw material and catalyst impact on the product quality. Considering the use of different catalysts, the results showed that, after 8 h of reaction, product purity was similar using the different catalysts, being 92.5 wt.% using both NaOH and calcium manganese oxide and 93.8 wt.% using CaO. The active species of the heterogeneous catalysts were CaO, in the case of calcinated calcium carbonate, and Ca 0.9 Mn 0.1 O, in the case of calcinated calcium manganese oxide. Because the deactivating species were different for both catalysts, the calcium manganese oxide required lower activation temperature, which should be an advantage

  16. Low temperature oxidation, co-oxidation and auto-ignition of olefinic and aromatic blending compounds: Experimental study of interactions during the oxidation of a surrogate fuel; Oxydation, co-oxydation et auto-inflammation a basses temperatures d'alcenes et aromatiques types: etude experimentale des interactions au sein d'un carburant-modele

    Energy Technology Data Exchange (ETDEWEB)

    Vanhove, G.

    2004-12-15

    The low-temperature (600-900 K) and high-pressure (5-25 bar) oxidation and auto-ignition of the three position isomers of hexene, of binary mixtures of 1-hexene, toluene and iso-octane, and of a surrogate fuel composed of these three compounds were studied in motor conditions using a rapid compression machine. Auto-ignition delay times were measured as long as intermediate products concentrations during the delay. The results show that the oxidation chemistry of the hexenes is very dependent on the position of the double bond inside the molecule, and that strong interactions between the oxidation mechanisms of hydrocarbons in mixtures can occur. The data obtained concerning the surrogate fuel give a good insight into the behaviour of a practical gasoline after an homogeneous charge compression. (author)

  17. The degradation of lining of rotary furnaces in the production of zinc oxide

    OpenAIRE

    Natália Luptáková; Evgeniy Anisimov; Františka Pešlová

    2014-01-01

    This paper is closely connected with the complex problem of degradation relating to the refractories of rotary furnace linings in the production of zinc oxide. Zinc oxide can be produced by variety of ways, but the most common method of production which is used in Europe is indirect, i.e. pyrolytic combustion of zinc. This method is also called "French process" of manufacturing ZnO. But this mentioned method of preparation leads to the creation of the enormous amount of zinc slag including ch...

  18. The Oxidation Products of Aluminum Hydride and Boron Aluminum Hydride Clusters

    Science.gov (United States)

    2016-01-04

    AFRL-AFOSR-VA-TR-2016-0075 The Oxidation Products of Aluminum Hydride and Boron Aluminum Hydride Clusters KIT BOWEN JOHNS HOPKINS UNIV BALTIMORE MD...2. REPORT TYPE Final Performance 3. DATES COVERED (From - To) 30-09-2014 to 29-09-2015 4. TITLE AND SUBTITLE The Oxidation Products of Aluminum ...Hydride and Boron Aluminum Hydride Clusters 5a.  CONTRACT NUMBER 5b.  GRANT NUMBER FA9550-14-1-0324 5c.  PROGRAM ELEMENT NUMBER 61102F 6. AUTHOR(S) KIT

  19. Oxidant production and SOD1 protein expression in single skeletal myofibers from Down syndrome mice

    Directory of Open Access Journals (Sweden)

    Patrick M. Cowley

    2017-10-01

    Full Text Available Down syndrome (DS is a genetic condition caused by the triplication of chromosome 21. Persons with DS exhibit pronounced muscle weakness, which also occurs in the Ts65Dn mouse model of DS. Oxidative stress is thought to be an underlying factor in the development of DS-related pathologies including muscle dysfunction. High-levels of oxidative stress have been attributed to triplication and elevated expression of superoxide dismutase 1 (SOD1; a gene located on chromosome 21. The elevated expression of SOD1 is postulated to increase production of hydrogen peroxide and cause oxidative injury and cell death. However, it is unknown whether SOD1 protein expression is associated with greater oxidant production in skeletal muscle from Ts65Dn mice. Thus, our objective was to assess levels of SOD1 expression and oxidant production in skeletal myofibers from the flexor digitorum brevis obtained from Ts65Dn and control mice. Measurements of oxidant production were obtained from myofibers loaded with 2′,7′-dichlorodihydrofluorescein diacetate (DCFH2-DA in the basal state and following 15 min of stimulated unloaded contraction. Ts65Dn myofibers exhibited a significant decrease in basal DCF emissions (p 0.05. Myofibers from Ts65Dn mice tended to be smaller and myonuclear domain was lower (p < 0.05. In summary, myofibers from Ts65Dn mice exhibited decreased basal DCF emissions that were coupled with elevated protein expression of SOD1. Stimulated contraction in isolated myofibers did not affect DCF emissions in either group. These findings suggest the skeletal muscle dysfunction in the adult Ts65Dn mouse is not associated with skeletal muscle oxidative stress.

  20. Short exposure to acetylene to distinguish between nitrifier and denitrifier nitrous oxide production in soil and sediment samples

    OpenAIRE

    Kester, R.A.; Boer, W. de; Laanbroek, H.J.

    1996-01-01

    The contribution of nitrifiers and denitrifiers to the nitrous oxide production in slurries of calcareous silt loam and river bank sediment at different oxygen concentrations was determined using acetylene as nitrification inhibitor. The addition of 10 Pa acetylene resulted in inhibition of nitrous oxide production at oxic conditions, but strongly enhanced the nitrous oxide production at oxygen-poor and anoxic conditions. Inhibition of nitrification by short exposure (1 to 24 h) to high conce...

  1. Reactions of clofibric acid with oxidative and reductive radicals—Products, mechanisms, efficiency and toxic effects

    International Nuclear Information System (INIS)

    Csay, Tamás; Rácz, Gergely; Salik, Ádám; Takács, Erzsébet; Wojnárovits, László

    2014-01-01

    The degradation of clofibric acid induced by hydroxyl radical, hydrated electron and O 2 −∙ /HO 2 ∙ reactive species was studied in aqueous solutions. Clofibric acid was decomposed more effectively by hydroxyl radical than by hydrated electron or O 2 −∙ /HO 2 ∙ . Various hydroxylated, dechlorinated and fragmentation products have been identified and quantified. A new LC–MS method was developed based on 18 O isotope labeling to follow the formation of hydroxylated derivatives of clofibric acid. Possible degradation pathways have been proposed. The overall degradation was monitored by determination of sum parameters like COD, TOC and AOX. It was found that the organic chlorine degrades very effectively prior to complete mineralization. After the treatment no toxic effect was found according to Vibrio fischeri tests. However, at early stages some of the reaction products were more harmful than clofibric acid. - Highlights: • Clofibric acid is effectively degraded by OH radical. • Main primary and secondary products are hydroxylated and dihydroxylated phenyl type derivatives of clofibric acid. • In air saturated aqueous solutions O 2 plays an important role in decomposition of the aromatic structure. • A new LC–MS method with 18 O-labeling was developed. • Early stage reaction products are more toxic to bacteria Vibrio fischeri than clofibric acid

  2. Birds and polycyclic aromatic hydrocarbons

    Science.gov (United States)

    Albers, P.H.

    2006-01-01

    Polycyclic aromatic hydrocarbons (PAH) are present throughout the global environment and are produced naturally and by activities of humans. Effects of PAH on birds have been determined by studies employing egg injection, egg immersion, egg shell application, single and multiple oral doses, subcutaneous injection, and chemical analysis of field-collected eggs and tissue. The four-to six-ring aromatic compounds are the most toxic to embryos, young birds, and adult birds. For embryos, effects include death, developmental abnormalities, and a variety of cellular and biochemical responses. For adult and young birds, effects include reduced egg production and hatching, increased clutch or brood abandonment, reduced growth, increased organweights, and a variety of biochemical responses. Trophic level accumulation is unlikely. Environmental exposure to PAH in areas of high human population or habitats affected by recent petroleum spills might be sufficient to adversely affect reproduction. Evidence of long-term effects of elevated concentrations of environmental PAH on bird populations is very limited and the mechanisms of effect are unclear.

  3. Formation of polycyclic aromatic hydrocarbons by ionizing radiations

    International Nuclear Information System (INIS)

    Perez, G.; Lilia, E.; Cristalli, A.

    1986-01-01

    Gaseous 0-terphenyl, 1-phenylnaphthalene, and 9-phenylanthracene were submitted to gamma rays. The yields of cyclization products, polycyclic aromatic hydrocarbons, show that at least one twentieth of the intermediates formed undergo intramolecular reaction. (author)

  4. Comparison of direct, headspace and headspace cold fiber modes in solid phase microextraction of polycyclic aromatic hydrocarbons by a new coating based on poly(3,4-ethylenedioxythiophene)/graphene oxide composite.

    Science.gov (United States)

    Banitaba, Mohammad Hossein; Hosseiny Davarani, Saied Saeed; Kazemi Movahed, Siyavash

    2014-01-17

    A novel nanocomposite coating made of poly(3,4-ethylenedioxythiophene) (PEDOT) and graphene oxide was electrochemically prepared on gold wire. The prepared fiber was applied to the solid-phase microextraction (SPME) and gas chromatographic analysis of six polycyclic aromatic hydrocarbons (PAHs). Three modes of extraction i.e. direct immersion (DI), headspace (HS) and headspace cold fiber (HS-CF) in SPME were investigated. The results were compared under optimized conditions of each mode, considering the effects of the three most important parameters which are extraction temperature, extraction time and ionic strength. The comparison showed that HS-CF-SPME results in the best outcome for the extraction of PAHs from water samples. Under the optimized conditions of this mode, the calibration curves were linear within the range of 0.4-600μgL(-1) and the detection limits were between 0.05 and 0.13μgL(-1). The intra-day and inter-day relative standard deviations obtained at 10μgL(-1) (n=5), using a single fiber, were 4.1-6.8% and 4.8-8.4%, respectively. The fiber-to-fiber repeatabilities (n=4), expressed as the relative standard deviations (RSD%), were between 6.5% and 10.7% at a 10μgL(-1) concentration level. The method was successfully applied to the analysis of PAHs in seawater samples showing recoveries from 85% to 107%. Copyright © 2013 Elsevier B.V. All rights reserved.

  5. Bis(trifluoromethanesulfonyl)imide-based ionic liquids grafted on graphene oxide-coated solid-phase microextraction fiber for extraction and enrichment of polycyclic aromatic hydrocarbons in potatoes and phthalate esters in food-wrap.

    Science.gov (United States)

    Hou, Xiudan; Guo, Yong; Liang, Xiaojing; Wang, Xusheng; Wang, Lei; Wang, Licheng; Liu, Xia

    2016-06-01

    A class of novel, environmental friendly ionic liquids (ILs) were synthesized by on-fiber preparation strategy and modified on graphene oxide (GO)-coated stainless steel wire, which was used as a solid-phase microextraction (SPME) fiber for efficient enrichment of polycyclic aromatic hydrocarbons (PAHs) and phthalate esters (PAEs). Surface characteristic of the ILs and polymeric-ILs (PILs) fibers with the wave-structure were inspected by scanning electron microscope. The successfully synthesis of bis(trifluoromethanesulfonyl)imide (NTf2(-))-based ILs were also characterized by energy dispersive spectrometer analysis. Through the chromatograms of the proposed two ILs (1-aminoethyl-3-methylimidazolium bromide (C2NH2MIm(+)Br(-)), C2NH2MIm(+)NTf2(-)) and two PILs (polymeric 1-vinyl-3-hexylimidazolium bromide (poly(VHIm(+)Br(-))), poly(VHIm(+)NTf2(-)))-GO-coated fibers for the extraction of analytes, NTf2(-)-based PIL demonstrated higher extraction capacity for hydrophobic compounds than other as-prepared ILs. Analytical performances of the proposed fibers were investigated under the optimized extraction and desorption conditions coupled with gas chromatography (GC). Compared with the poly(VHIm(+)Br(-))-GO fiber, the poly(VHIm(+)NTf2(-))-GO SPME fiber brought wider linear ranges for analytes with correlation coefficient in the range of 0.9852-0.9989 and lower limits of detection ranging from 0.015-0.025μgL(-1). The obtained results indicated that the newly prepared PILs-GO coating was a feasible, selective and green microextraction medium, which could be suitable for extraction and determination of PAHs and PAEs in potatoes and food-wrap sample, respectively. Copyright © 2016 Elsevier B.V. All rights reserved.

  6. Durable solid oxide electrolysis cells for hydrogen production

    DEFF Research Database (Denmark)

    Sun, Xiufu; Chen, Ming; Hendriksen, Peter Vang

    2014-01-01

    production is required for promoting commercialization of the SOEC technology. In this work, we report a recent 4400 hours test of a state-of-the-art Ni-YSZ electrode supported SOEC cell. The cell consists of a Ni-YSZ (YSZ: yttria stabilized zirconia) support and active fuel electrode, an YSZ electrolyte...... that except for the first 250 hours fast initial degradation, for the rest of the testing period, the cell showed rather stable performance with an moderate degradation rate of around 25 mV/1000 h. The electrochemical impedance spectra show that both serial resistance and polarization resistance of the cell...... and changing of porosity inside the active layer. The degree of these microstructural changes becomes less and less severe along the hydrogen-steam flow path. The present test results show that this type of cell can be used for early demonstration electrolysis at 1A/cm2. Future work should be focus on reducing...

  7. Large-scale Modeling of Nitrous Oxide Production: Issues of Representing Spatial Heterogeneity

    Science.gov (United States)

    Morris, C. K.; Knighton, J.

    2017-12-01

    Nitrous oxide is produced from the biological processes of nitrification and denitrification in terrestrial environments and contributes to the greenhouse effect that warms Earth's climate. Large scale modeling can be used to determine how global rate of nitrous oxide production and consumption will shift under future climates. However, accurate modeling of nitrification and denitrification is made difficult by highly parameterized, nonlinear equations. Here we show that the representation of spatial heterogeneity in inputs, specifically soil moisture, causes inaccuracies in estimating the average nitrous oxide production in soils. We demonstrate that when soil moisture is averaged from a spatially heterogeneous surface, net nitrous oxide production is under predicted. We apply this general result in a test of a widely-used global land surface model, the Community Land Model v4.5. The challenges presented by nonlinear controls on nitrous oxide are highlighted here to provide a wider context to the problem of extraordinary denitrification losses in CLM. We hope that these findings will inform future researchers on the possibilities for model improvement of the global nitrogen cycle.

  8. Epiphytes modulate Posidonia oceanica photosynthetic production, energetic balance, antioxidant mechanisms and oxidative damage

    Directory of Open Access Journals (Sweden)

    Monya Mendes Costa

    2015-12-01

    Full Text Available Epiphytes impose physical barriers to light penetration into seagrass leaves causing shading, which may decrease the production of oxygen reactive species (ROS, but also constitute a physical aggression that may trigger the production of ROS, leading to oxidative damage. Here we investigate the effects of epiphytes on Posidonia oceanica under both interactive perspectives, light attenuation and oxidative stress. Specifically the role of epiphytes in net photosynthesis, chlorophyll a and b, photoprotection (Violaxanthin+Anteraxanthin+Zeaxanthin cycle, soluble sugar and starch contents, enzymatic (ascorbate peroxidase (APX and dehydroascorbate reductase (DHAR and global (trolox equivalent antioxidant capacity (TEAC and oxygen radical antioxidant capacity (ORAC antioxidant responses, phenolics and oxidative damage (malondialdehyde are tested. Leaves with epiphytes showed higher chlorophyll b and lower content in VAZ cycle carotenoids. Epiphyte shading was the probable reason for the lower VAZ de-epoxidation-ratio of leaves with epiphytes. In spite of being shaded, leaves with epiphytes showed higher antioxidant levels, indicating that epiphytes trigger the production of ROS. Both ORAC and TEAC and also APX and DHAR activities were higher in leaves with epiphytes, indicating that this response was related with its presence. Malondialdehyde concentrations also suggest oxidative damage caused by epiphytes. We conclude that the epiphyte load causes oxidative stress in P. oceanica and the mechanisms to scavenge ROS were not completely effective to avoid cell damage.

  9. Advanced Oxidation Protein Products and Carbonylated Proteins as Biomarkers of Oxidative Stress in Selected Atherosclerosis-Mediated Diseases

    Directory of Open Access Journals (Sweden)

    Bogna Gryszczyńska

    2017-01-01

    Full Text Available Objectives. The main question of this study was to evaluate the intensity of oxidative protein modification shown as advanced oxidation protein products (AOPP and carbonylated proteins, expressed as protein carbonyl content (C=O in abdominal aortic aneurysms (AAA, aortoiliac occlusive disease (AIOD, and chronic kidney disease (CKD. Design and Methods. The study was carried out in a group of 35 AAA patients and 13 AIOD patients. However, CKD patients were divided into two groups: predialysis (PRE included 50 patients or hemodialysis (HD consisted of 34 patients. AOPP and C=O were measured using colorimetric assay kit, while C-reactive protein concentration was measured by high-sensitivity assay (hsCRP. Results. The concentration of AOPP in both AAA and AIOD groups was higher than in PRE and HD groups according to descending order: AAA~AIOD > HD > PRE. The content of C=O was higher in the PRE group in comparison to AIOD and AAA according to the descending order: PRE~HD > AAA~AIOD. Conclusions. AAA, AIOD, and CKD-related atherosclerosis (PRE and HD contribute to the changes in the formation of AOPP and C=O. They may promote modification of proteins in a different way, probably due to the various factors that influence oxidative stress here.

  10. Flavone inhibits nitric oxide synthase (NOS) activity, nitric oxide production and protein S-nitrosylation in breast cancer cells

    Energy Technology Data Exchange (ETDEWEB)

    Zhu, Wenzhen; Yang, Bingwu; Fu, Huiling; Ma, Long; Liu, Tingting; Chai, Rongfei; Zheng, Zhaodi [Shandong Provincial Key Laboratory of Animal Resistant Biology, School of Life Sciences, Shandong Normal University, Jinan 250014 (China); Zhang, Qunye, E-mail: wz.zhangqy@sdu.edu.cn [Key Laboratory of Cardiovascular Remodeling and Function Research Chinese Ministry of Education and Ministry of Public Health, Qilu Hospital, Shandong University, Jinan, Shandong (China); Li, Guorong, E-mail: grli@sdnu.edu.cn [Shandong Provincial Key Laboratory of Animal Resistant Biology, School of Life Sciences, Shandong Normal University, Jinan 250014 (China)

    2015-03-13

    As the core structure of flavonoids, flavone has been proved to possess anticancer effects. Flavone's growth inhibitory functions are related to NO. NO is synthesized by nitric oxide synthase (NOS), and generally increased in a variety of cancer cells. NO regulates multiple cellular responses by S-nitrosylation. In this study, we explored flavone-induced regulations on nitric oxide (NO)-related cellular processes in breast cancer cells. Our results showed that, flavone suppresses breast cancer cell proliferation and induces apoptosis. Flavone restrains NO synthesis by does-dependent inhibiting NOS enzymatic activity. The decrease of NO generation was detected by fluorescence microscopy and flow cytometry. Flavone-induced inhibitory effect on NOS activity is dependent on intact cell structure. For the NO-induced protein modification, flavone treatment significantly down-regulated protein S-nitrosylation, which was detected by “Biotin-switch” method. The present study provides a novel, NO-related mechanism for the anticancer function of flavone. - Highlights: • Flavone inhibits proliferation and induces apoptosis in MCF-7 cells. • Flavone decreases nitric oxide production by inhibiting NOS enzymatic activity in breast cancer cells. • Flavone down-regulates protein S-nitrosylation.

  11. Flavone inhibits nitric oxide synthase (NOS) activity, nitric oxide production and protein S-nitrosylation in breast cancer cells

    International Nuclear Information System (INIS)

    Zhu, Wenzhen; Yang, Bingwu; Fu, Huiling; Ma, Long; Liu, Tingting; Chai, Rongfei; Zheng, Zhaodi; Zhang, Qunye; Li, Guorong

    2015-01-01

    As the core structure of flavonoids, flavone has been proved to possess anticancer effects. Flavone's growth inhibitory functions are related to NO. NO is synthesized by nitric oxide synthase (NOS), and generally increased in a variety of cancer cells. NO regulates multiple cellular responses by S-nitrosylation. In this study, we explored flavone-induced regulations on nitric oxide (NO)-related cellular processes in breast cancer cells. Our results showed that, flavone suppresses breast cancer cell proliferation and induces apoptosis. Flavone restrains NO synthesis by does-dependent inhibiting NOS enzymatic activity. The decrease of NO generation was detected by fluorescence microscopy and flow cytometry. Flavone-induced inhibitory effect on NOS activity is dependent on intact cell structure. For the NO-induced protein modification, flavone treatment significantly down-regulated protein S-nitrosylation, which was detected by “Biotin-switch” method. The present study provides a novel, NO-related mechanism for the anticancer function of flavone. - Highlights: • Flavone inhibits proliferation and induces apoptosis in MCF-7 cells. • Flavone decreases nitric oxide production by inhibiting NOS enzymatic activity in breast cancer cells. • Flavone down-regulates protein S-nitrosylation

  12. CYP-450 isoenzymes catalyze the generation of hazardous aromatic amines after reaction with the azo dye Sudan III.

    Science.gov (United States)

    Zanoni, Thalita Boldrin; Lizier, Thiago M; Assis, Marilda das Dores; Zanoni, Maria Valnice B; de Oliveira, Danielle Palma

    2013-07-01

    This work describes the mutagenic response of Sudan III, an adulterant food dye, using Salmonella typhimurium assay and the generation of hazardous aromatic amines after different oxidation methods of this azo dye. For that, we used metabolic activation by S9, catalytic oxidation by ironporphyrin and electrochemistry oxidation in order to simulate endogenous oxidation conditions. The oxidation reactions promoted discoloration from 65% to 95% of Sudan III at 1 × 10(-4)molL(-1) and generation of 7.6 × 10(-7)molL(-1) to 0.31 × 10(-4)molL(-1) of aniline, o-anisidine, 2-methoxi-5-methylaniline, 4-aminobiphenyl, 4,4'-oxydianiline; 4,4'-diaminodiphenylmethane and 2,6-dimethylaniline. The results were confirmed by LC-MS-MS experiments. We also correlate the mutagenic effects of Sudan III using S. typhimurium with the strain TA1535 in the presence of exogenous metabolic activation (S9) with the metabolization products of this compound. Our findings clearly indicate that aromatic amines are formed due to oxidative reactions that can be promoted by hepatic cells, after the ingestion of Sudan III. Considering that, the use of azo compounds as food dyestuffs should be carefully controlled. Copyright © 2013 Elsevier Ltd. All rights reserved.

  13. Oxidative stress and production of bioactive monoterpene indole alkaloids: biotechnological implications.

    Science.gov (United States)

    Matsuura, Hélio Nitta; Rau, Mariana Ritter; Fett-Neto, Arthur Germano

    2014-02-01

    Monoterpene indole alkaloids (MIAs) encompass plant natural products with important pharmacological relevance. They include the anti-tumoral MIAs found in Catharanthus roseus and Camptotheca acuminata. The often low yields of bioactive alkaloids in plants has prompted research to identify the factors regulating MIA production. Oxidative stress is a general response associated with biotic and abiotic stresses leading to several secondary responses, including elicitation of MIA production. These changes in secondary metabolism may take place directly or via second messengers, such as Ca(2+) and reactive oxygen species (ROS). H2O2 is the main ROS that participates in MIA biosynthesis. This review analyzes the links between oxidative stress, elicitation of bioactive MIA production and their potential roles in antioxidant defense, as well as exploring the implications to developing biotechnological strategies relevant for alkaloid supply.

  14. Phenyltrichlorosilane-functionalized magnesium oxide microspheres: Preparation, characterization and application for the selective extraction of dioxin-like polycyclic aromatic hydrocarbons in soils with matrix solid-phase dispersion

    Energy Technology Data Exchange (ETDEWEB)

    Tan, Dongqin [Key Laboratory of Separation Science for Analytical Chemistry, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, No. 457 Zhongshan Road, Dalian 116023 (China); University of Chinese Academy of Sciences, Beijing 100049 (China); Jin, Jing [Key Laboratory of Separation Science for Analytical Chemistry, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, No. 457 Zhongshan Road, Dalian 116023 (China); Li, Fang [Shenzhen Institutes of Advanced Technology, Chinese Academy of Science, Shenzhen 518055 (China); Sun, Xiaoli [Department of Chemistry, Lishui University, Lishui 32300 (China); Dhanjai; Ni, Yuwen [Key Laboratory of Separation Science for Analytical Chemistry, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, No. 457 Zhongshan Road, Dalian 116023 (China); Chen, Jiping, E-mail: chenjp@dicp.ac.cn [Key Laboratory of Separation Science for Analytical Chemistry, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, No. 457 Zhongshan Road, Dalian 116023 (China)

    2017-03-01

    Magnesium oxide microspheres functionalized with phenyltrichlorosilane (PTS-MgO) were synthesized by surface modification through silanization reaction, which was confirmed by Fourier transform infrared (FT-IR), scanning electron microscopy (SEM), X-ray diffraction (XRD), thermogravimetry analysis (TGA) and N{sub 2} adsorption-desorption. The result indicated that PTS-MgO not only possessed the ability of enhancing the retention with PAHs, but also weakening the interference from chlorinated compounds. As a sorbent for the matrix solid-phase dispersion (MSPD) extraction, PTS-MgO was used to selectively extract seven dioxin-like polycyclic aromatic hydrocarbons (DL-PAHs) from soil samples. Various parameters affecting the recoveries of seven DL-PAHs were investigated and optimized, such as sorbent/sample mass ratio, grinding time, rinsing and eluting conditions. Under the optimized conditions, the developed method combining MSPD with HPLC-FLD exhibited good sensitivity (0.02–0.12 ng g{sup −1} detection of limits) and linearity (linear correlation coefficient greater than 0.9997). Satisfactory recoveries with DL-PAHs spiked at two levels (10 and 80 ng g{sup −1}) were obtained in the range of 72.2–113.1% with RSD < 9.6%, indicating that PTS-MgO had a potential in MSPD extraction of DL-PAHs in soils. Additionally, the proposed MSPD-HPLC-FLD method was also verified by detecting seven DL-PAHs in the standard reference soil. Based on the developed method, DL-PAHs in soil samples were detected with the concentration ranging from 70.08 to 555.05 ng g{sup −1} dry weight (dw). The total toxic equivalency quotients (TEQ) of seven DL-PAHs varied from 9.93 to 143.94 ng TEQ/g dw. - Highlights: • Phenyltrichlorosilane modified magnesium oxide microsphere (PTS-MgO) was presented. • PTS-MgO was used for a new sorbent material in matrix solid-phase dispersion. • The sorbent showed high selectivity for DL-PAHs with satisfactory recoveries obtained. • The

  15. Observations of oxidation products above a forest imply biogenic emissions of very reactive compounds

    Directory of Open Access Journals (Sweden)

    R. Holzinger

    2005-01-01

    Full Text Available Vertical gradients of mixing ratios of volatile organic compounds have been measured in a Ponderosa pine forest in Central California (38.90° N, 120.63° W, 1315m. These measurements reveal large quantities of previously unreported oxidation products of short lived biogenic precursors. The emission of biogenic precursors must be in the range of 13-66µmol m-2h-1 to produce the observed oxidation products. That is 6-30 times the emissions of total monoterpenes observed above the forest canopy on a molar basis. These reactive precursors constitute a large fraction of biogenic emissions at this site, and are not included in current emission inventories. When oxidized by ozone they should efficiently produce secondary aerosol and hydroxyl radicals.

  16. Progesterone modulates the LPS-induced nitric oxide production by a progesterone-receptor independent mechanism.

    Science.gov (United States)

    Wolfson, Manuel Luis; Schander, Julieta Aylen; Bariani, María Victoria; Correa, Fernando; Franchi, Ana María

    2015-12-15

    Genital tract infections caused by Gram-negative bacteria induce miscarriage and are one of the most common complications of human pregnancy. LPS administration to 7-day pregnant mice induces embryo resorption after 24h, with nitric oxide playing a fundamental role in this process. We have previously shown that progesterone exerts protective effects on the embryo by modulating the inflammatory reaction triggered by LPS. Here we sought to investigate whether the in vivo administration of progesterone modulated the LPS-induced nitric oxide production from peripheral blood mononuclear cells from pregnant and non-pregnant mice. We found that progesterone downregulated LPS-induced nitric oxide production by a progesterone receptor-independent mechanism. Moreover, our results suggest a possible participation of glucocorticoid receptors in at least some of the anti-inflammatory effects of progesterone. Copyright © 2015 Elsevier B.V. All rights reserved.

  17. Study of Nitric Oxide production by murine peritoneal macrophages induced by Brucella Lipopolysaccharide

    Directory of Open Access Journals (Sweden)

    Kavoosi G

    2001-07-01

    Full Text Available Brueclla is a gram negative bacteria that causes Brucellosis. Lipopolysaccharide (LPS ", the pathogenic agent of Brucella is composed of O-chain, core oligosaccharide and lipid A. in addition, the structural and biological properties of different LPS extracted from different strains are not identical. The first defense system against LPS is nonspecific immunity that causes macrophage activation. Activated macrophages produce oxygen and nitrogen radicals that enhance the protection against intracellular pathogens.In this experiment LPS was extracted by hot phenol- water procedure and the effect of various LPSs on nitric oxide prodution by peritoneal mouse macrophages was examined.Our results demonstrated that the effect of LPS on nitric oxide production is concentration-dependent we observed the maximum response in concentration of 10-20 microgram per milliliter. Also our results demonstrate that LPS extracted from vaccine Brucella abortus (S 19 had a highe effect on nitric oxide production than the LPS from other strains

  18. Experimental and simulation analysis of hydrogen production by partial oxidation of methanol

    Energy Technology Data Exchange (ETDEWEB)

    Sikander, U. [National Univ. of Science and Technology, Islamabad (Pakistan)

    2014-10-15

    Partial oxidation of methanol is the only self-sustaining process for onboard production of hydrogen. For this a fixed bed catalytic reactor is designed, based on heterogeneous catalytic reaction. To develop an optimized process, simulation is carried out using ASPEN HYSYS v 7.1. Reaction kinetics is developed on the basis of Langmuir Hinshel wood model. 45:55:5 of CuO: ZnO: Al/sub 2/O/sub 3/ is used as a catalyst. Simulation results are studied in detail to understand the phenomenon of partial oxidation of methanol inside the reactor. An experimental rig is developed for hydrogen production through partial oxidation of methanol. Results obtained from process simulation and experimental work; are compared with each other. (author)

  19. Influence of corium oxidation on fission product release from molten pool

    Energy Technology Data Exchange (ETDEWEB)

    Bechta, S.V., E-mail: bechta@sbor.spb.s [Alexandrov Scientific-Research Institute of Technology (NITI), Sosnovy Bor (Russian Federation); Krushinov, E.V.; Vitol, S.A.; Khabensky, V.B.; Kotova, S.Yu.; Sulatsky, A.A. [Alexandrov Scientific-Research Institute of Technology (NITI), Sosnovy Bor (Russian Federation); Gusarov, V.V.; Almyashev, V.I. [Grebenschikov Institute of Silicate Chemistry of the Russian Academy of Sciences (ISC RAS), St. Petersburg (Russian Federation); Ducros, G.; Journeau, C. [CEA, DEN, Cadarache, F-13108 St. Paul lez Durance (France); Bottomley, D. [Joint Research Centre Institut fuer Transurane (ITU), Karlsruhe (Germany); Clement, B. [Institut de Radioprotection et Surete Nucleaire (IRSN), St. Paul lez Durance (France); Herranz, L. [CIEMAT, Madrid (Spain); Guentay, S. [PSI, Wuerenlingen (Switzerland); Trambauer, K. [GRS, Muenchen (Germany); Auvinen, A. [VTT, Espoo (Finland); Bezlepkin, V.V. [SPbAEP, St. Petersburg (Russian Federation)

    2010-05-15

    Qualitative and quantitative determination of the release of low-volatile fission products and core materials from molten oxidic corium was investigated in the EVAN project under the auspices of ISTC. The experiments carried out in a cold crucible with induction heating and RASPLAV test facility are described. The results are discussed in terms of reactor application; in particular, pool configuration, melt oxidation kinetics, critical influence of melt surface temperature and oxidation index on the fission product release rate, aerosol particle composition and size distribution. The relevance of measured high release of Sr from the molten pool for the reactor application is highlighted. Comparisons of the experimental data with those from the COLIMA CA-U3 test and the VERCORS tests, as well as with predictions from IVTANTHERMO and GEMINI/NUCLEA codes are made. Recommendations for further investigations are proposed following the major observations and discussions.

  20. Influence of corium oxidation on fission product release from molten pool

    International Nuclear Information System (INIS)

    Bechta, S.V.; Krushinov, E.V.; Vitol, S.A.

    2009-01-01

    Release of low-volatile fission products and core materials from molten oxidic corium was investigated in the EVAN project under the auspices of ISTC. The experiments carried out in cold crucible with induction heating and RASPLAV test facility are described. The results are discussed in terms of reactor application; in particular, pool configuration, melt oxidation kinetics, critical influence of melt surface temperature and oxidation index on the fission product release rate and aerosol particle composition. The relevance of measured high release of Sr from the molten pool for the reactor application is highlighted. Comparisons of the experimental data with those from the COLIMA CA-U3 test and the VERCORS tests, as well as with predictions from IVTANTHERMO and GEMINI/NUCLEA are set. (author)

  1. Study of cryoprotectors effect on oxidation processes at storage of frozen halffinished products

    Directory of Open Access Journals (Sweden)

    O. Glushkov

    2016-12-01

    Full Text Available The publication presents data on the effect of polysaccharides as cryoprotectants on changes of the lipid fraction of quick-frozen semi-finished products during storage. Since the structure of minced systems is formed as a result of the destruction of the native structure of the meat and the formation of a new secondary structure, it is important to establish the effect of cryoprotectants on the key functional and technological properties of meat systems after freezing, and in the process of storage. Based on studies of the kinetics of the oxidation of fat and accumulation data on the accumulation of the primary and secondary products of oxidation inhibition of oxidative processes has been found.

  2. Analysis of phosphatidylcholine oxidation products in human plasma using quadrupole time-of flight mass spectrometry

    OpenAIRE

    Adachi, Junko; Asano, Migiwa; Yoshioka, Naoki; Nushida, Hideyuki; Ueno, Yasuhiro

    2006-01-01

    We report here an application of the previous method for the analysis ofphosphatidylcholine (PC) and lysophosphatidylcholine (lysoPC) oxidation products inhuman plasma using quadrupole time of flight (Q-TOF) mass spectrometry withelectrospray ionization. We separated these products using an HPLC C8 column witha gradient of methanol and 10 mM aqueous ammonium acetate. Monohydroperoxides,epoxyhydroxy derivatives, oxo derivatives, and trihydroxides of palmitoyl-linoleoyl(C16:0/C18:2) PC and stea...

  3. Life Time Performance Characterization of Solid Oxide Electrolysis Cells for Hydrogen Production

    DEFF Research Database (Denmark)

    Sun, Xiufu; Chen, Ming; Liu, Yi-Lin

    2015-01-01

    Solid oxide electrolysis cells (SOECs) offer a promising technological solution for efficient energy conversion and production of hydrogen or syngas. The commercialization of the SOEC technology can be promoted if SOECs can be operated at high current density with stable performance over ~5 years...... - 3 years (continuous operation, setting 1.5 V as the upper voltage defining “end of life”). The results provide technological input to future design of electrolysis plants for hydrogen production. © 2015 ECS - The Electrochemical Society...

  4. Impact of green tea extract addition on oxidative changes in the lipid fraction of pastry products.

    Science.gov (United States)

    Żbikowska, Anna; Kowalska, Małgorzata; Rutkowska, Jarosława; Kozłowska, Mariola; Onacik-Gür, Sylwia

    2017-01-01

    Alongside flour, fat is the key ingredient of sponge cakes, including those with long shelf lives. It is an unstable food component, whose quality and nutritional safety depend on the composition and pres- ence of oxidation products. Consumption of fat oxidation products adversely affects the human body and contributes to the incidence of a number of medical conditions. Qualitative changes in fats extracted from thermostat sponge cakes with and without antioxidant additions were determined in this study. In the study, two types of antioxidant were used: natural - green tea extract in three doses (0.02%; 0.2% and 1.0%) and synthetic BHA (0.02%) and 100%, solid bakery shortening. Sponge-cakes were thermostatted at temperatures 63°C after twenty-eight days. In this study, the quality of the lipid fraction was analyzed. The amount of primary (PV) and secondary (AnV) oxidation products was determined, and   a Rancimat test was performed. Adding antioxidants to fats varied in the degree to which oxidation processes of lipids fractions were inhibited. The peroxide value after twenty-eight days of thermostatting ranged from 3.57 meq O/kg (BHA) and 11.14 O meq/kg (extract content - 1%) to 62.85 meq O/kg (control sample). In turn, the value of AnV after the storage period ranged from 4.84 (BHA) and 6.71 (extract content - 1%) to 16.83 (control sample). The best protective effects in the process of oxidation was achieved by BHA. The longest in- duction time and the lowest peroxide value and anisidine value were obtained for this antioxidant. It was achieved after twenty-eight days of fat thermostatting. Nonetheless, the results demonstrated it is possible to use the commercially available green tea extract to slow the adverse process of fat oxidation in sponge cake products.

  5. Plasmon-enhanced Solar Fuel Production with Gold-metal Oxide Hybrid Nanomaterials

    DEFF Research Database (Denmark)

    Engelbrekt, Christian; Law, Matt; Zhang, Jingdong

    , provide new catalytic routes and expands the scope of solar photocatalysis. We prepare metal oxide SNPs, gold PNPs and their hybrids through mild aqueous syntheses to develop efficient photocatalyst for solar fuel production. Focus is placed on the synergetic interplay between SNPs and PNPs, understanding...

  6. 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.

  7. In vivo measurement of nitric oxide production in porcine gut, liver and muscle during hyperdynamic endotoxaemia

    NARCIS (Netherlands)

    Bruins, Maaike J.; Lamers, Wouter H.; Meijer, Alfred J.; Soeters, Peter B.; Deutz, Nicolaas E. P.

    2002-01-01

    1. During prolonged endotoxaemia, an increase in arginine catabolism may result in limiting substrate availability for nitric oxide (NO) production. These effects were quantitated in a chronically instrumented porcine endotoxaemia model. 2. Ten days prior to the beginning of the experiments, pigs

  8. AMMONIA REMOVAL AND NITROUS OXIDE PRODUCTION IN GAS-PHASE COMPOST BIOFILTERS

    Science.gov (United States)

    Biofiltration technology is widely utilized for treating ammonia gas (NH3), with one of its potential detrimental by-products being nitrous oxide (N2O), a greenhouse gas approximately 300 times more reactive to infrared than CO2. The present work intends to provide the relation between NH3 removal d...

  9. Selective production of hydrogen peroxide and oxidation of hydrogen sulfide in an unbiased solar photoelectrochemical cell

    DEFF Research Database (Denmark)

    Zong, Xu; Chen, Hongjun; Seger, Brian

    2014-01-01

    A solar-to-chemical conversion process is demonstrated using a photoelectrochemical cell without external bias for selective oxidation of hydrogen sulfide (H2S) to produce hydrogen peroxide (H2O2) and sulfur (S). The process integrates two redox couples anthraquinone/anthrahydroquinone and I−/I3......−, and conceptually illustrates the remediation of a waste product for producing valuable chemicals....

  10. Serum uric acid levels and leukocyte nitric oxide production in multiple sclerosis patients outside relapses

    NARCIS (Netherlands)

    Mostert, JP; Ramsaransing, GSM; Heerserna, DJ; Heerings, M; Wilczak, N; De Keyser, J

    2005-01-01

    Background: A number of studies found that patients with multiple sclerosis (MS) have low serum levels of uric acid. It is unclear whether this represents a primary deficit or secondary effect. Uric acid is a scavenger of peroxynitrite, which is the product of nitric oxide (NO) and superoxide.

  11. Oxidation of trimethoprim by ferrate(VI): kinetics, products, and antibacterial activity.

    Science.gov (United States)

    Anquandah, George A K; Sharma, Virender K; Knight, D Andrew; Batchu, Sudha Rani; Gardinali, Piero R

    2011-12-15

    Kinetics, stoichiometry, and products of the oxidation of trimethoprim (TMP), one of the most commonly detected antibacterial agents in surface waters and municipal wastewaters, by ferrate(VI) (Fe(VI)) were determined. The pH dependent second-order rate constants of the reactions of Fe(VI) with TMP were examined using acid-base properties of Fe(VI) and TMP. The kinetics of reactions of diaminopyrimidine (DAP) and trimethoxytoluene (TMT) with Fe(VI) were also determined to understand the reactivity of Fe(VI) with TMP. Oxidation products of the reactions of Fe(VI) with TMP and DAP were identified by liquid chromatography-tandem mass spectrometry (LC-MS/MS). Reaction pathways of oxidation of TMP by Fe(VI) are proposed to demonstrate the cleavage of the TMP molecule to ultimately result in 3,4,5,-trimethoxybenzaldehyde and 2,4-dinitropyrimidine as among the final identified products. The oxidized products mixture exhibited no antibacterial activity against E. coli after complete consumption of TMP. Removal of TMP in the secondary effluent by Fe(VI) was achieved.

  12. Simple Methods for Production of Nanoscale Metal Oxide Films from Household Sources

    Science.gov (United States)

    Campbell, Dean J.; Baliss, Michelle S.; Hinman, Jordan J.; Ziegenhorn, John W.; Andrews, Mark J.; Stevenson, Keith J.

    2013-01-01

    Production of thin metal oxide films was recently explored as part of an outreach program with a goal of producing nanoscale structures with household items. Household items coated with various metals or titanium compounds can be heated to produce colorful films with nanoscale thicknesses. As part of a materials chemistry laboratory experiment…

  13. Thermo-Oxidization of Municipal Wastewater Treatment Plant Sludge for Production of Class A Biosolids

    Science.gov (United States)

    Bench-scale reactors were used to test a novel thermo-oxidation process on municipal wastewater treatment plant (WWTP) waste activated sludge (WAS) using hydrogen peroxide (H2O2) to achieve a Class A sludge product appropriate for land application. Reactor ...

  14. Primary oxidation and reduction products in x-irradiated aspartic acid

    International Nuclear Information System (INIS)

    Adams, S.M.; Budzinski, E.E.; Box, H.C.

    1976-01-01

    The primary reduction products identified by ESR--ENDOR spectroscopy in single crystals of DL-aspartic acid hydrochloride irradiated at 4.2degreeK are anions formed by addition of an electron to the carbonyl oxygen atoms of the carboxylic acid groups. The main consequence of the oxidation process is to produce a hole centered mainly on atomic chlorine

  15. Nitrogen loss from grassland on peat soils through nitrous oxide production.

    NARCIS (Netherlands)

    Koops, J.G.; Beusichem, van M.L.; Oenema, O.

    1997-01-01

    Nitrous oxide (N2O) in soils is produced through nitrification and denitrification. The N2O produced is considered as a nitrogen (N) loss because it will most likely escape from the soil to the atmosphere as N2O or N2. Aim of the study was to quantify N2O production in grassland on peat soils in

  16. Conformations of double-headed, triple-tailed phospholipid oxidation lipid products in model membranes

    DEFF Research Database (Denmark)

    Hermetter, Albin; Kopec, Wojciech; Khandelia, Himanshu

    2013-01-01

    Products of phospholipid oxidation can produce lipids with a carbonyl moiety at the end of a shortened lipid acyl tail, such as 1-palmitoyl-2-(5-oxovaleroyl)-sn-glycero-3-phosphocholine (POVPC). The carbonyl tail of POVPC can covalently bond to the free tertiary amine of a phosphatidylethanolamine...

  17. Production of nitrogen oxides in air pulse-periodic discharge with apokamp

    Science.gov (United States)

    Panarin, Victor A.; Skakun, Victor S.; Sosnin, Eduard A.; Tarasenko, Victor F.

    2018-05-01

    The decomposition products of pulse-periodic discharge atmospheric pressure plasma in apokamp, diffuse and corona modes were determined by optical and chemical methods. It is shown that apokamp discharge formation starts at a critical value of dissipation power in a discharge channel. Simultaneously, due to the thermochemical reactions, plasma starts to efficiently produce nitrogen oxides.

  18. THE EFFECTS OF EQUIVALENCE RATIO ON THE FORMATION OF POLYCYCLIC AROMATIC HYDROCARBONS AND SOOT IN PREMIXED ETHANE FLAMES. (R825412)

    Science.gov (United States)

    AbstractThe formation of polycyclic aromatic hydrocarbons (PAH) and soot has been investigated in atmospheric-pressure, laminar, ethane/oxygen/argon premixed flames as a function of mixture equivalence ratio. Mole fraction profiles of major products, trace aromatics, ...

  19. Identification of the Products of Oxidation of Quercetin by Air Oxygenat Ambient Temperature

    Directory of Open Access Journals (Sweden)

    Viktor A Utsal

    2007-03-01

    Full Text Available Oxidation of quercetin by air oxygen takes place in water and aqueous ethanol solutions under mild conditions, namely in moderately-basic media (pH ∼ 8-10 at ambient temperature and in the absence of any radical initiators, without enzymatic catalysis or irradiation of the reaction media by light. The principal reaction products are typical of other oxidative degradation processes of quercetin, namely 3,4-dihydroxy-benzoic (proto-catechuic and 2,4,6-trihydroxybenzoic (phloroglucinic acids, as well as the decarboxylation product of the latter – 1,3,5-trihydroxybenzene (phloroglucinol. In accordance with the literature data, this process involves the cleavage of the γ-pyrone fragment (ring C of the quercetin molecule by oxygen, with primary formation of 4,6-dihydroxy-2-(3,4-dihydroxybenzoyloxybenzoic acid (depside. However under such mild conditions the accepted mechanism of this reaction (oxidative decarbonylation with formation of carbon monoxide, CO should be reconsidered as preferably an oxidative decarboxylation with formation of carbon dioxide, CO2. Direct head-space analysis of the gaseous components formed during quercetin oxidation in aqueous solution at ambient temperature indicates that the ratio of carbon dioxide/carbon monoxide in the gas phase after acidification of the reaction media is ca. 96:4 %. Oxidation under these mild conditions is typical for other flavonols having OH groups at C3 (e.g., kaempferol, but it is completely suppressed if this hydroxyl group is substituted by a glycoside fragment (as in rutin, or a methyl substituent. An alternative oxidation mechanism involving the direct cleavage of the C2-C3 bond in the diketo-tautomer of quercetin is proposed.

  20. Effects of silver nanoparticles on nitrification and associated nitrous oxide production in aquatic environments.

    Science.gov (United States)

    Zheng, Yanling; Hou, Lijun; Liu, Min; Newell, Silvia E; Yin, Guoyu; Yu, Chendi; Zhang, Hongli; Li, Xiaofei; Gao, Dengzhou; Gao, Juan; Wang, Rong; Liu, Cheng

    2017-08-01

    Silver nanoparticles (AgNPs) are the most common materials in nanotechnology-based consumer products globally. Because of the wide application of AgNPs, their potential environmental impact is currently a highly topical focus of concern. Nitrification is one of the processes in the nitrogen cycle most susceptible to AgNPs but the specific effects of AgNPs on nitrification in aquatic environments are not well understood. We report the influence of AgNPs on nitrification and associated nitrous oxide (N 2 O) production in estuarine sediments. AgNPs inhibited nitrification rates, which decreased exponentially with increasing AgNP concentrations. The response of nitrifier N 2 O production to AgNPs exhibited low-dose stimulation (production could be enhanced by >100% at low doses of AgNPs. This result was confirmed by metatranscriptome studies showing up-regulation of nitric oxide reductase (norQ) gene expression in the low-dose treatment. Isotopomer analysis revealed that hydroxylamine oxidation was the main N 2 O production pathway, and its contribution to N 2 O emission was enhanced when exposed to low-dose AgNPs. This study highlights the molecular underpinnings of the effects of AgNPs on nitrification activity and demonstrates that the release of AgNPs into the environment should be controlled because they interfere with nitrifying communities and stimulate N 2 O emission.

  1. PRODUCTION OF HYDROGEN FROM THE STEAM AND OXIDATIVE REFORMING OF LPG: THERMODYNAMIC AND EXPERIMENTAL STUDY

    Directory of Open Access Journals (Sweden)

    P. P. Silva

    2015-09-01

    Full Text Available AbstractThe objective of this paper was to use a thermodynamic analysis to find operational conditions that favor the production of hydrogen from steam and oxidative reforming of liquefied petroleum gas (LPG. We also analyzed the performance of a catalyst precursor, LaNiO3, in order to compare the performance of the obtained catalyst with the thermodynamic equilibrium predictions. The results showed that it is possible to produce high concentrations of hydrogen from LPG reforming. The gradual increase of temperature and the use of high water concentrations decrease the production of coke and increase the formation of H2. The reaction of oxidative reforming of LPG was more suitable for the production of hydrogen and lower coke formation. Furthermore the use of an excess of water (H2O/LPG =7.0 and intermediate temperatures (973 K are the most suitable conditions for the process.

  2. Low-Energy, Low-Cost Production of Ethylene by Low- Temperature Oxidative Coupling of Methane

    Energy Technology Data Exchange (ETDEWEB)

    Radaelli, Guido [Siluria Technologies, Inc., San Francisco, CA (United States); Chachra, Gaurav [Siluria Technologies, Inc., San Francisco, CA (United States); Jonnavittula, Divya [Siluria Technologies, Inc., San Francisco, CA (United States)

    2017-12-30

    In this project, we develop a catalytic process technology for distributed small-scale production of ethylene by oxidative coupling of methane at low temperatures using an advanced catalyst. The Low Temperature Oxidative Coupling of Methane (LT-OCM) catalyst system is enabled by a novel chemical catalyst and process pioneered by Siluria, at private expense, over the last six years. Herein, we develop the LT-OCM catalyst system for distributed small-scale production of ethylene by identifying and addressing necessary process schemes, unit operations and process parameters that limit the economic viability and mass penetration of this technology to manufacture ethylene at small-scales. The output of this program is process concepts for small-scale LT-OCM catalyst based ethylene production, lab-scale verification of the novel unit operations adopted in the proposed concept, and an analysis to validate the feasibility of the proposed concepts.

  3. Oxidative stability of pork emulsion containing tomato products and pink guava pulp during refrigerated aerobic storage.

    Science.gov (United States)

    Joseph, Serlene; Chatli, Manish K; Biswas, Ashim K; Sahoo, Jhari

    2014-11-01

    Lipid oxidation-induced quality problems can be minimized with the use of natural antioxidants. Antioxidant potential of tomato puree (10 %; T-1), tomato pulp (12.5 %; T-2), lyophilized tomato peel (6 %; T-3), and pink guava pulp (10 %; T-4) was evaluated in raw pork emulsion during refrigerated storage for 9 days under aerobic packaging. The lycopene and β-carotene content varied in pork emulsion as T-3 > T-1 > T-2 > T-4 and decreased (P emulsions than in control. Overall, incorporation of tomato products and pink guava pulp improved the visual colour and odour scores of raw pork emulsion. These results indicated that tomato products and guava pulp can be utilized as sources of natural antioxidants in raw pork products to minimize lipid oxidation, off-odour development, and surface discolouration.

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

    International Nuclear Information System (INIS)

    Liu, Yanjie; Wang, Zhenyao; Ke, Wei

    2014-01-01

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

  5. Electrochemistry-High Resolution Mass Spectrometry to Study Oxidation Products of Trimethoprim

    Directory of Open Access Journals (Sweden)

    Marc-André Lecours

    2018-01-01

    Full Text Available The study of the fate of emerging organic contaminants (EOCs, especially the identification of transformation products, after water treatment or in the aquatic environment, is a topic of growing interest. In recent years, electrochemistry coupled to mass spectrometry has attracted a lot of attention as an alternative technique to investigate oxidation metabolites of organic compounds. The present study used different electrochemical approaches, such as cyclic voltammetry, electrolysis, electro-assisted Fenton reaction coupled offline to high resolution mass spectrometry and thin-layer flow cell coupled online to high resolution mass spectrometry, to study oxidation products of the anti-infective trimethoprim, a contaminant of emerging concern frequently reported in wastewaters and surface waters. Results showed that mono- and di-hydroxylated derivatives of trimethoprim were generated in electrochemically and possibly tri-hydroxylated derivatives as well. Those compounds have been previously reported as mammalian and bacterial metabolites as well as transformation products of advance oxidation processes applied to waters containing trimethoprim. Therefore, this study confirmed that electrochemical techniques are relevant not only to mimic specific biotransformation reactions of organic contaminants, as it has been suggested previously, but also to study the oxidation reactions of organic contaminants of interest in water treatment. The key role that redox reactions play in the environment make electrochemistry-high resolution mass spectrometry a sensitive and simple technique to improve our understanding of the fate of organic contaminants in the environment.

  6. Serum Advanced Oxidation Protein Products in Oral Squamous Cell Carcinoma: Possible Markers of Diagnostic Significance

    Directory of Open Access Journals (Sweden)

    Abhishek Singh Nayyar

    2013-07-01

    Full Text Available Background: The aim of this study was to measure the concentrations (levels ofserum total proteins and advanced oxidation protein products as markers of oxidantmediated protein damage in the sera of patients with oral cancers.Methods: The study consisted of the sera analyses of serum total protein andadvanced oxidation protein products’ levels in 30 age and sex matched controls, 60patients with reported pre-cancerous lesions and/or conditions and 60 patients withhistologically proven oral squamous cell carcinoma. One way analyses of variance wereused to test the difference between groups. To determine which of the two groups’ meanswere significantly different, the post-hoc test of Bonferroni was used. The results wereaveraged as mean ± standard deviation. In the above test, P values less than 0.05 weretaken to be statistically significant. The normality of data was checked before thestatistical analysis was performed.Results: The study revealed statistically significant variations in serum levels ofadvanced oxidation protein products (P<0.001. Serum levels of total protein showedextensive variations; therefore the results were largely inconclusive and statisticallyinsignificant.Conclusion: The results emphasize the need for more studies with larger samplesizes to be conducted before a conclusive role can be determined for sera levels of totalprotein and advanced oxidation protein products as markers both for diagnosticsignificance and the transition from the various oral pre-cancerous lesions and conditionsinto frank oral cancers.

  7. A model for the release of low-volatility fission products in oxidizing conditions

    International Nuclear Information System (INIS)

    Cox, D.S.; Hunt, C.E.L.; Liu, Z.; Keller, N.A.; Barrand, R.D.; O'Connor, R.F.

    1991-07-01

    A thermodynamic and kinetic model has been developed for calculating low-volatility fission-product releases from UO 2 at high temperatures in oxidizing conditions. Volatilization of the UO 2 matrix is assumed to be the rate controlling process. Oxidation kinetics of the UO 2 are modelled by either interfacial rate control, gas phase oxidant transport control, or solid-state diffusion of oxygen. The vapour pressure of UO 3 in equilibrium with the oxidizing fuel is calculated from thermodynamic data, and volatilization rates are determined using a model for forced convective mass transport. Low-volatility fission-product releases are calculated from the volume of vapourized fuel. Model calculations are conservative compared to experimental data for Zr, La, Ce and Nb fission-product releases from irradiated UO 2 exposed to air at 1973-2350 K. The implications of this conservatism are discussed in terms of possible rate control by processes other than convective mass transport of UO 3 . Coefficients for effective surface area (based on experimental data) and for heterogeneous rate controlling reaction kinetics are introduced to facilitate agreement between calculations and the experimental data.

  8. Enhanced 15-HPETE production during oxidant stress induces apoptosis of endothelial cells.

    Science.gov (United States)

    Sordillo, Lorraine M; Weaver, James A; Cao, Yu-Zhang; Corl, Chris; Sylte, Matt J; Mullarky, Isis K

    2005-05-01

    Oxidant stress plays an important role in the etiology of vascular diseases by increasing rates of endothelial cell apoptosis, but few data exist on the mechanisms involved. Using a unique model of oxidative stress based on selenium deficiency (-Se), the effects of altered eicosanoid production on bovine aortic endothelial cells (BAEC) apoptosis was evaluated. Oxidant stress significantly increased the immediate oxygenation product of arachidonic acid metabolized by the 15-lipoxygenase pathway, 15-hydroxyperoxyeicosatetraenoic acid (15-HPETE). Treatment of -Se BAEC with TNFalpha/cyclohexamide (CHX) exhibited elevated levels of apoptosis, which was significantly reduced by the addition of a specific 15-lipoxygenase inhibitor PD146176. Furthermore, the addition of 15-HPETE to PD146176-treated BAEC, partially restored TNF/CHX-induced apoptosis. Increased exposure to 15-HPETE induced apoptosis, as determined by internucleosomal DNA fragmentation, chromatin condensation, caspase-3 activation, and caspase-9 activation, which suggests mitochondrial dysfunction. The expression of Bcl-2 protein also was decreased in -Se BAEC. Addition of a caspase-9 inhibitor (LEHD-fmk) completely blocked 15-HPETE-induced chromatin condensation in -Se BAEC, suggesting that 15-HPETE-induced apoptosis is caspase-9 dependent. Increased apoptosis of BAEC as a result of oxidant stress and subsequent production of 15-HPETE may play a critical role in a variety of inflammatory based diseases.

  9. Aromatic metabolism of filamentous fungi in relation to the presence of aromatic compounds in plant biomass

    NARCIS (Netherlands)

    Mäkelä, Miia R; Marinović, Mila; Nousiainen, Paula; Liwanag, April J M; Benoit, Isabelle; Sipilä, Jussi; Hatakka, Annele; de Vries, Ronald P; Hildén, Kristiina S

    2015-01-01

    The biological conversion of plant lignocellulose plays an essential role not only in carbon cycling in terrestrial ecosystems but also is an important part of the production of second generation biofuels and biochemicals. The presence of the recalcitrant aromatic polymer lignin is one of the major

  10. The formation of highly oxidized multifunctional products in the ozonolysis of cyclohexene

    DEFF Research Database (Denmark)

    Rissanen, Matti P.; Kurtén, Theo; Sipilä, Mikko

    2014-01-01

    ionization atmospheric pressure interface time-of-flight mass spectrometer with a nitrate ion (NO3 -)-based ionization scheme. Quantum chemical calculations were performed at the CCSD(T)-F12a/VDZ-F12//ωB97XD/aug-cc-pVTZ level, with kinetic modeling using multiconformer transition state theory, including...... of seconds. Dimerization of the peroxy radicals by recombination and cross-combination reactions is in competition with the formation of highly oxidized monomer species and is observed to lead to peroxides, potentially diacyl peroxides. The molar yield of these highly oxidized products (having O/C > 1...

  11. Nitrous oxide production and consumption potential in an agricultural and a forest soil

    DEFF Research Database (Denmark)

    Yu, Kewei; Struwe, Sten; Kjøller, Annelise

    2008-01-01

    Both a laboratory incubation experiment using soils from an agricultural field and a forest and field measurements at the same locations were conducted to determine nitrous oxide (N2O) production and consumption (reduction) potentials using the acetylene (C2H2) inhibition technique. Results from...... measurements show that average N2O emission rates were 0.56 and 0.59 kg N ha-1 in the agricultural field and forest, respectively. When C2H2 was provided in the field measurements, N2O emission rates from the agricultural field and forest increased by 38 and 51%, respectively. Nitrous oxide consumption under...

  12. 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.

  13. Possibilities for production of medicinal aromatic plants on the spoil bank of the Pljevlja coal mine. Mogucnost gajenja ljekovitog i aromaticnog bilja na jalovistu rudnika uglja - Pljevlja

    Energy Technology Data Exchange (ETDEWEB)

    Memic, M.; Bajovic, L. (Rudnik Uglja Pljevlja (Yugoslavia))

    1990-01-01

    Presents results obtained from experimental recultivation of the Potrlica surface coal mine spoil bank (810 m elevation, continental climate) during 1986-1990. Two experimental fields - Potrlica-I (600 m[sup 2]) and Potrlica-II (300 m[sup 2]) - were prepared by spreading a 10-20 cm thick layer of low-quality soil over the marly waste of the spoil bank. Soil composition was: 2.10% and 74% Ca, 4.5% and 0.70% humus, l3.5% and 5.5% P[sub 2]O[sub 5] and 23.0% and 6.0% K[sub 2]O in Potrlica-I and II respectively. Soil pH values were 7.2 and 7.60; 500 kg/ha NPK (15:15:15) were spread. Seventeen species of aromatic and medicinal plants were grown. After four years the plants were classified into 3 groups (thriving, satisfactory and non-thriving). It was found that the following plants can yield satisfactory crops and profits: valeriana officinalis, hyssopus officinalis, artemis dracunculus, cynaris scolimus, foenculum vulgare and malva silvestris. Unsatisfactory results were obtained with melisa officinalis, coriandrum sativum, pimpinela anisum and angelica archangelica. Experiments will be continued.

  14. Genus Cistus: a model for exploring labdane-type diterpenes' biosynthesis and a natural source of high value products with biological, aromatic and pharmacological properties

    Science.gov (United States)

    Papaefthimiou, Dimitra; Papanikolaou, Antigoni; Falara, Vasiliki; Givanoudi, Stella; Kostas, Stefanos; Kanellis, Angelos

    2014-06-01

    The family Cistaceae (Angiosperm, Malvales) consists of 8 genera and 180 species, with 5 genera native of the Mediterranean area (Cistus, Fumara, Halimium, Helianthemum and Tuberaria). Traditionally, a number of Cistus specie have been used in Mediterranean folk medicine as herbal tea infusions for healing, digestive problems and colds, as extracts for the treatment of diseases, and as fragrances. The resin, ladano, secreted by the glandular trichomes of certain Cistus species contains a number of phytochemicals with antioxidant, antibacterial, antifungal and anticancer properties. Furthermore, total leaf aqueous extracts possess anti-influenza virus activity. All these properties have been attributed to phytochemicals such as terpenoids, including diterpenes, labdane-type diterpenes and clerodanes, phenylpropanoids, including flavonoids and ellagitannins, several groups of alkaloids and other types of secondary metabolites. In the past 20 years, research on Cistus involved chemical, biological and phylogenetic analysis but recent investigations have involved genomic and molecular approaches. Our lab is exploring the biosynthetic machinery that generates terpenoids and phenylpropanoids, with a goal to harness their numerous properties that have applications in the pharmaceutical, chemical and aromatic industries. This review focuses on the systematics, botanical characteristics, geographic distribution, chemical analyses, biological function and biosynthesis of major compounds, as well as genomic analyses and biotechnological approaches of the main Cistus species found in the Mediterranean basin, namely C. albidus, C. creticus, C. crispus, C. parviflorus, C. monspeliensis, C. populifolius, C. salviifolius, C. ladanifer, C. laurifolius and C. clusii.

  15. HPLC Separation of Vitamin E and Its Oxidation Products and Effects of Oxidized Tocotrienols on the Viability of MCF-7 Breast Cancer Cells in Vitro.

    Science.gov (United States)

    Drotleff, Astrid M; Büsing, Anne; Willenberg, Ina; Empl, Michael T; Steinberg, Pablo; Ternes, Waldemar

    2015-10-14

    Tocotrienols, a vitamin E subgroup, exert potent anticancer effects, but easily degrade due to oxidation. Eight vitamin E reference compounds, α-, β-, γ-, or δ-tocopherols or -tocotrienols, were thermally oxidized in n-hexane. The corresponding predominantly dimeric oxidation products were separated from the parent compounds by diol-modified normal-phase HPLC-UV and characterized by mass spectroscopy. The composition of test compounds, that is, α-tocotrienol, γ-tocotrienol, or palm tocotrienol-rich fraction (TRF), before and after thermal oxidation was determined by HPLC-DAD, and MCF-7 cells were treated with both nonoxidized and oxidized test compounds for 72 h. Whereas all nonoxidized test compounds (0-100 μM) led to dose-dependent decreases in cell viability, equimolar oxidized α-tocotrienol had a weaker effect, and oxidized TRF had no such effect. However, the IC50 value of oxidized γ-tocotrienol was lower (85 μM) than that of nonoxidized γ-tocotrienol (134 μM), thereby suggesting that γ-tocotrienol oxidation products are able to reduce tumor cell viability in vitro.

  16. Comprehensive Analysis of the Gas- and Particle-Phase Products of VOC Oxidation

    Science.gov (United States)

    Bakker-Arkema, J.; Ziemann, P. J.

    2017-12-01

    Controlled environmental chamber studies are important for determining atmospheric reaction mechanisms and gas and aerosol products formed in the oxidation of volatile organic compounds (VOCs). Such information is necessary for developing detailed chemical models for use in predicting the atmospheric fate of VOCs and also secondary organic aerosol (SOA) formation. However, complete characterization of atmospheric oxidation reactions, including gas- and particle-phase product yields, and reaction branching ratios, are difficult to achieve. In this work, we investigated the reactions of terminal and internal alkenes with OH radicals in the presence of NOx in an attempt to fully characterize the chemistry of these systems while minimizing and accounting for the inherent uncertainties associated with environmental chamber experiments. Gas-phase products (aldehydes formed by alkoxy radical decomposition) and particle-phase products (alkyl nitrates, β-hydroxynitrates, dihydroxynitrates, 1,4-hydroxynitrates, 1,4-hydroxycarbonyls, and dihydroxycarbonyls) formed through pathways involving addition of OH to the C=C double bond as well as H-atom abstraction were identified and quantified using a suite of analytical techniques. Particle-phase products were analyzed in real time with a thermal desorption particle beam mass spectrometer; and off-line by collection onto filters, extraction, and subsequent analysis of functional groups by derivatization-spectrophotometric methods developed in our lab. Derivatized products were also separated by liquid chromatography for molecular quantitation by UV absorbance and identification using chemical ionization-ion trap mass spectrometry. Gas phase aldehydes were analyzed off-line by collection onto Tenax and a 5-channel denuder with subsequent analysis by gas chromatography, or by collection onto DNPH-coated cartridges and subsequent analysis by liquid chromatography. The full product identification and quantitation, with careful

  17. Hybrid Nitrous Oxide Production from a Partial Nitrifying Bioreactor: Hydroxylamine Interactions with Nitrite.

    Science.gov (United States)

    Terada, Akihiko; Sugawara, Sho; Hojo, Keisuke; Takeuchi, Yuki; Riya, Shohei; Harper, Willie F; Yamamoto, Tomoko; Kuroiwa, Megumi; Isobe, Kazuo; Katsuyama, Chie; Suwa, Yuichi; Koba, Keisuke; Hosomi, Masaaki

    2017-03-07

    The goal of this study was to elucidate the mechanisms of nitrous oxide (N 2 O) production from a bioreactor for partial nitrification (PN). Ammonia-oxidizing bacteria (AOB) enriched from a sequencing batch reactor (SBR) were subjected to N 2 O production pathway tests. The N 2 O pathway test was initiated by supplying an inorganic medium to ensure an initial NH 4 + -N concentration of 160 mg-N/L, followed by 15 NO 2 - (20 mg-N/L) and dual 15 NH 2 OH (each 17 mg-N/L) spikings to quantify isotopologs of gaseous N 2 O ( 44 N 2 O, 45 N 2 O, and 46 N 2 O). N 2 O production was boosted by 15 NH 2 OH spiking, causing exponential increases in mRNA transcription levels of AOB functional genes encoding hydroxylamine oxidoreductase (haoA), nitrite reductase (nirK), and nitric oxide reductase (norB) genes. Predominant production of 45 N 2 O among N 2 O isotopologs (46% of total produced N 2 O) indicated that coupling of 15 NH 2 OH with 14 NO 2 - produced N 2 O via N-nitrosation hybrid reaction as a predominant pathway. Abiotic hybrid N 2 O production was also observed in the absence of the AOB-enriched biomass, indicating multiple pathways for N 2 O production in a PN bioreactor. The additional N 2 O pathway test, where 15 NH 4 + was spiked into 400 mg-N/L of NO 2 - concentration, confirmed that the hybrid N 2 O production was a dominant pathway, accounting for approximately 51% of the total N 2 O production.

  18. Suppression of grasshopper sound production by nitric oxide-releasing neurons of the central complex

    Science.gov (United States)

    Weinrich, Anja; Kunst, Michael; Wirmer, Andrea; Holstein, Gay R.

    2008-01-01

    The central complex of acridid grasshoppers integrates sensory information pertinent to reproduction-related acoustic communication. Activation of nitric oxide (NO)/cyclic GMP-signaling by injection of NO donors into the central complex of restrained Chorthippus biguttulus females suppresses muscarine-stimulated sound production. In contrast, sound production is released by aminoguanidine (AG)-mediated inhibition of nitric oxide synthase (NOS) in the central body, suggesting a basal release of NO that suppresses singing in this situation. Using anti-citrulline immunocytochemistry to detect recent NO production, subtypes of columnar neurons with somata located in the pars intercerebralis and tangential neurons with somata in the ventro-median protocerebrum were distinctly labeled. Their arborizations in the central body upper division overlap with expression patterns for NOS and with the site of injection where NO donors suppress sound production. Systemic application of AG increases the responsiveness of unrestrained females to male calling songs. Identical treatment with the NOS inhibitor that increased male song-stimulated sound production in females induced a marked reduction of citrulline accumulation in central complex columnar and tangential neurons. We conclude that behavioral situations that are unfavorable for sound production (like being restrained) activate NOS-expressing central body neurons to release NO and elevate the behavioral threshold for sound production in female grasshoppers. PMID:18574586

  19. Polycyclic Aromatic Hydrocarbon, Haematological and Oxidative ...

    African Journals Online (AJOL)

    Background: Human exposure to hazardous substances in the environment has been known to play an important role in the pathogenesis of some diseases. Photocopying machines have become a ... This will help to prevent or manage continuous exposure to the hazards of photocopying machines. Keywords: Photocopier ...

  20. Model-based evaluation of the role of Anammox on nitric oxide and nitrous oxide productions in membrane aerated biofilm reactor

    DEFF Research Database (Denmark)

    Ni, Bing-Jie; Smets, Barth F.; Yuan, Zhiguo

    2013-01-01

    A multispecies one-dimensional biofilm model considering nitric oxide (NO) and nitrous oxide (N2O) productions for membrane aerated biofilm reactor (MABR) that remove nitrogen autotrophically through aerobic ammonia oxidation followed by Anammox is used to study the role of Anammox activity...... on the total nitrogen (TN) removal and the productions of NO and N2O. The model is applied to evaluate how periodic aeration as a control parameter reduces NO and N2O production but maintains high TN removal in MABR. The simulation results show over 3.5% of the removed TN could be attributed to NO and N2O...... production in MABR under the operational conditions optimal for TN removal (72%). An analysis of factors governing the Anammox activity in MABR shows that enhancing Anammox activity not only helps to achieve a high level of nitrogen removal but also reduces NO and N2O productions. Comparison of aeration...