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Sample records for fluorescent aromatic compounds

  1. Detection of chlorinated aromatic compounds

    DOEpatents

    Ekechukwu, Amy A.

    1996-01-01

    A method for making a composition for measuring the concentration of chloated aromatic compounds in aqueous fluids, and an optical probe for use with the method. The composition comprises a hydrophobic polymer matrix, preferably polyamide, with a fluorescent indicator uniformly dispersed therein. The indicator fluoresces in the presence of the chlorinated aromatic compounds with an intensity dependent on the concentration of these compounds in the fluid of interest, such as 8-amino-2-naphthalene sulfonate. The probe includes a hollow cylindrical housing that contains the composition in its distal end. The probe admits an aqueous fluid to the probe interior for exposure to the composition. An optical fiber transmits excitation light from a remote source to the composition while the indicator reacts with chlorinated aromatic compounds present in the fluid. The resulting fluorescence light signal is reflected to a second optical fiber that transmits the light to a spectrophotometer for analysis.

  2. Detection of chlorinated aromatic compounds

    DOEpatents

    Ekechukwu, A.A.

    1996-02-06

    A method for making a composition for measuring the concentration of chlorinated aromatic compounds in aqueous fluids, and an optical probe for use with the method are disclosed. The composition comprises a hydrophobic polymer matrix, preferably polyamide, with a fluorescent indicator uniformly dispersed therein. The indicator fluoresces in the presence of the chlorinated aromatic compounds with an intensity dependent on the concentration of these compounds in the fluid of interest, such as 8-amino-2-naphthalene sulfonate. The probe includes a hollow cylindrical housing that contains the composition in its distal end. The probe admits an aqueous fluid to the probe interior for exposure to the composition. An optical fiber transmits excitation light from a remote source to the composition while the indicator reacts with chlorinated aromatic compounds present in the fluid. The resulting fluorescence light signal is reflected to a second optical fiber that transmits the light to a spectrophotometer for analysis. 5 figs.

  3. Significance of Cytochrome P450 System Responses and Levels of Bile Fluorescent Aromatic Compounds in Marine Wildlife Following Oil Spills

    SciTech Connect

    Lee, Richard F.; Anderson, Jack W.

    2005-07-01

    The relationships among cytochrome P450 induction in marine wildlife species, levels of fluorescent aromatic compounds (FAC) in their bile, the chemical composition of the inducing compounds, the significance of the exposure pathway, and any resulting injury, as a consequence of exposure to crude oil following a spill, are reviewed. Fish collected after oil spills often show increases in cytochrome P450 system activity, cytochrome P4501A (CYP1A) and bile fluorescent aromatic compounds (FAC), that are correlated with exposure to polycyclic aromatic hydrocarbons (PAH) in the oil. There is also some evidence for increases in bile FAC and induction of cytochrome P450 in marine birds and mammals after oil spills. However, when observed, increases in these exposure indicators are transitory and generally decrease to background levels within one year after the exposure. Laboratory studies have shown induction of cytochrome P450 systems occurs after exposure of fish to crude oil in water, sediment or food. Most of the PAH found in crude oil (dominantly 2- and 3-ring PAH) are not strong inducers of cytochrome P450. Exposure to the 4-ring chrysenes or the photooxidized products of the PAH may account for the cytochrome P450 responses in fish collected from oil-spill sites. The contribution of non-spill background PAH, particularly combustion-derived (pyrogenic) PAH, to bile FAC and cytochrome P450 system responses can be confounding and needs to be considered when evaluating oil spill effects. The ubiquity of pyrogenic PAH makes it important to fully characterize all sources of PAH, including PAH from natural resources, e.g. retene, in oil spill studies. In addition, such parameters as species, sex, age, ambient temperature and season need to be taken into account. While increases in fish bile FAC and cytochrome P450 system responses, can together, be sensitive general indicators of PAH exposure after an oil spill, there is little unequivocal evidence to suggest a linkage to

  4. Device for aqueous detection of nitro-aromatic compounds

    DOEpatents

    Reagen, W.K.; Schulz, A.L.; Ingram, J.C.; Lancaster, G.D.; Grey, A.E.

    1994-04-26

    This invention relates to a compact and portable detection apparatus for nitro-aromatic based chemical compounds, such as nitrotoluenes, dinitrotoluenes, and trinitrotoluene (TNT). The apparatus is based upon the use of fiber optics using filtered light. The preferred process of the invention relies upon a reflective chemical sensor and optical and electronic components to monitor a decrease in fluorescence when the nitro-aromatic molecules in aqueous solution combine and react with a fluorescent polycyclic aromatic compound. 4 figures.

  5. Device for aqueous detection of nitro-aromatic compounds

    DOEpatents

    Reagen, William K.; Schulz, Amber L.; Ingram, Jani C.; Lancaster, Gregory D.; Grey, Alan E.

    1994-01-01

    This invention relates to a compact and portable detection apparatus for ro-aromatic based chemical compounds, such as nitrotoluenes, dinitrotoluenes, and trinitrotoluene (TNT). The apparatus is based upon the use of fiber optics using filtered light. The preferred process of the invention relies upon a reflective chemical sensor and optical and electronic components to monitor a decrease in fluorescence when the nitro-aromatic molecules in aqueous solution combine and react with a fluorescent polycyclic aromatic compound.

  6. Bacterial Degradation of Aromatic Compounds

    PubMed Central

    Seo, Jong-Su; Keum, Young-Soo; Li, Qing X.

    2009-01-01

    Aromatic compounds are among the most prevalent and persistent pollutants in the environment. Petroleum-contaminated soil and sediment commonly contain a mixture of polycyclic aromatic hydrocarbons (PAHs) and heterocyclic aromatics. Aromatics derived from industrial activities often have functional groups such as alkyls, halogens and nitro groups. Biodegradation is a major mechanism of removal of organic pollutants from a contaminated site. This review focuses on bacterial degradation pathways of selected aromatic compounds. Catabolic pathways of naphthalene, fluorene, phenanthrene, fluoranthene, pyrene, and benzo[a]pyrene are described in detail. Bacterial catabolism of the heterocycles dibenzofuran, carbazole, dibenzothiophene, and dibenzodioxin is discussed. Bacterial catabolism of alkylated PAHs is summarized, followed by a brief discussion of proteomics and metabolomics as powerful tools for elucidation of biodegradation mechanisms. PMID:19440284

  7. Alkylation of organic aromatic compounds

    DOEpatents

    Smith, L.A. Jr.; Arganbright, R.P.; Hearn, D.

    1993-09-07

    Aromatic compounds are alkylated in a catalytic distillation, wherein the catalyst structure also serves as a distillation component by contacting the aromatic compound with a C[sub 2] to C[sub 10] olefin in the catalyst bed under 0.25 to 50 atmospheres of pressure and at temperatures in the range of 80 C to 500 C, using as the catalyst a molecular sieve characterized as acidic or an acidic cation exchange resin. For example, ethyl benzene is produced by feeding ethylene to about the mid point of the catalyst bed while benzene is conveniently added through the reflux in molar excess to that required to react with ethylene, thereby reacting substantially all of the ethylene and recovering benzene as the principal overhead and ethyl benzene in the bottoms. 1 figures.

  8. Alkylation of organic aromatic compounds

    DOEpatents

    Smith, Jr., Lawrence A.; Arganbright, Robert P.; Hearn, Dennis

    1994-01-01

    Aromatic compounds are alkylated in a catalytic distillation, wherein the catalyst structure also serves as a distillation component by contacting the aromatic compound with a C.sub.2 to C.sub.10 olefin in the catalyst bed under 0.25 to 50 atmospheres of pressure and at temperatures in the range of 80.degree. C. to 500.degree. C., using as the catalyst a mole sieve characterized as acidic or an acidic cation exchange resin. For example, ethyl benzene is produced by feeding ethylene below the catalyst bed while benzene is conveniently added through the reflux in molar excess to that required to react with ethylene, thereby reacting substantially all of the ethylene and recovering benzene as the principal overhead and ethyl benzene in the bottoms.

  9. Alkylation of organic aromatic compounds

    DOEpatents

    Smith, L.A. Jr.; Arganbright, R.P.; Hearn, D.

    1994-06-14

    Aromatic compounds are alkylated in a catalytic distillation, wherein the catalyst structure also serves as a distillation component by contacting the aromatic compound with a C[sub 2] to C[sub 10] olefin in the catalyst bed under 0.25 to 50 atmospheres of pressure and at temperatures in the range of 80 C to 500 C, using as the catalyst a molecular sieve characterized as acidic or an acidic cation exchange resin. For example, ethyl benzene is produced by feeding ethylene below the catalyst bed while benzene is conveniently added through the reflux in molar excess to that required to react with ethylene, thereby reacting substantially all of the ethylene and recovering benzene as the principal overhead and ethyl benzene in the bottoms. 1 fig.

  10. Alkylation of organic aromatic compounds

    DOEpatents

    Smith, Jr., Lawrence A.

    1989-01-01

    Aromatic compounds are alkylated in a catalytic distillation, wherein the catalyst structure also serves as a distillation component by contacting the aromatic compound with a C.sub.2 to C.sub.10 olefin in the catalyst bed under 0.25 to 50 atmospheres of pressure and at temperatures in the range of 80.degree. C. to 500.degree. C., using as the catalyst a mole sieve characterized as acidic or an acidic cation exchange resin. For example, ethyl benzene is produced by feeding ethylene below the catalyst bed while benzene is conveniently added through the reflux in molar excess to that required to react with ethylene, thereby reacting substantially all of the ethylene and recovering benzene as the principal overhead and ethyl benzene in the bottoms.

  11. Alkylation of organic aromatic compounds

    DOEpatents

    Smith, Jr., Lawrence A.; Arganbright, Robert P.; Hearn, Dennis

    1993-01-01

    Aromatic compounds are alkylated in a catalytic distillation, wherein the catalyst structure also serves as a distillation component by contacting the aromatic compound with a C.sub.2 to C.sub.10 olefin in the catalyst bed under 0.25 to 50 atmospheres of pressure and at temperatures in the range of 80.degree. C. to 500.degree. C., using as the catalyst a mole sieve characterized as acidic or an acidic cation exchange resin. For example, ethyl benzene is produced by feeding ethylene to about the mid point of the catalyst bed while benzene is conveniently added through the reflux in molar excess to that required to react with ethylene, thereby reacting substantially all of the ethylene and recovering benzene as the principal overhead and ethyl benzene in the bottoms.

  12. Alkylation of organic aromatic compounds

    DOEpatents

    Smith, L.A. Jr.

    1989-07-18

    Aromatic compounds are alkylated in a catalytic distillation, wherein the catalyst structure also serves as a distillation component by contacting the aromatic compound with a C[sub 2] to C[sub 10] olefin in the catalyst bed under 0.25 to 50 atmospheres of pressure and at temperatures in the range of 80 C to 500 C, using as the catalyst a mole sieve characterized as acidic or an acidic cation exchange resin. For example, ethyl benzene is produced by feeding ethylene below the catalyst bed while benzene is conveniently added through the reflux in molar excess to that required to react with ethylene, thereby reacting substantially all of the ethylene and recovering benzene as the principal overhead and ethyl benzene in the bottoms. 1 fig.

  13. Time-resolved detection of aromatic compounds on planetary surfaces by ultraviolet laser induced fluorescence and Raman spectroscopy

    NASA Astrophysics Data System (ADS)

    Eshelman, E.; Daly, M. G.; Slater, G.; Cloutis, E.

    2015-12-01

    Raman spectroscopic instruments are highly capable in the search for organics on Mars due to the potential to perform rapid and nondestructive measurements on unprepared samples. Upcoming and future Raman instruments are likely to also incorporate laser-induced fluorescence (LIF) capabilities, which can be added for modest cost and complexity. We demonstrate that it is possible to obtain sub-ns fluorescence lifetime measurements of Mars-relevant organics and minerals if a fast time-gating capability is used with an intensified detector and a short ultraviolet laser pulse. This serves a primary purpose of discriminating mineral from short-lived (less than 10 ns) organic fluorescence, considered a potential biosignature. Additionally, lifetime measurements may assist in determining if more than one fluorescing species is present and provide information concerning the molecular structure as well as the local environment. Fast time-gating is also useful at longer visible or near-IR wavelengths, as this approach increases the sensitivity of the instrument to organic material by removing the majority of the fluorescence background from the Raman signal and reducing the effect of ambient light.

  14. Alkylation of organic aromatic compounds

    DOEpatents

    Smith, L.A. Jr.; Arganbright, R.P.; Hearn, D.

    1993-01-05

    Aromatic compounds are alkylated in a combination reactor/distillation column comprising a vessel suitable for operating between 70 C and 500 C and from 0.5 to 20 atmospheres pressure; an inert distillation packing in the lower one-third of said vessel; solid acidic catalytic material such as zeolites or an acidic cation exchange resin supported in the middle one-third of said vessel; and inert distillation packing in the upper one-third of said vessel. A benzene inlet is located near the upper end of the vessel; an olefin inlet is juxtaposed with said solid acidic catalytic material; a bottoms outlet is positioned near the bottom of said vessel for removing said cumene and ethyl benzene; and an overhead outlet is placed at the top of said vessel for removing any unreacted benzene and olefin.

  15. Alkylation of organic aromatic compounds

    DOEpatents

    Smith, Jr., Lawrence A.; Arganbright, Robert P.; Hearn, Dennis

    1993-01-01

    Aromatic compounds are alkylated in a combination reactor/distillation column comprising a vessel suitable for operating between 70.degree. C. and 500.degree. C. and from 0.5 to 20 atmospheres pressure; an inert distillation packing in the lower one-third of said vessel; solid acidic catalytic material such as zeolites or an acidic cation exchange resin supported in the middle one-third of said vessel; and inert distillation packing in the upper one-third of said vessel. A benzene inlet is located near the upper end of the vessel; an olefin inlet is juxtaposed with said solid acidic catalytic material; a bottoms outlet is positioned near the bottom of said vessel for removing said cumene and ethyl benzene; and an overhead outlet is placed at the top of said vessel for removing any unreacted benzene and olefin.

  16. Anaerobic biodegradation of aromatic compounds.

    PubMed

    Jothimani, P; Kalaichelvan, G; Bhaskaran, A; Selvaseelan, D Augustine; Ramasamy, K

    2003-09-01

    Many aromatic compounds and their monomers are existing in nature. Besides they are introduced into the environment by human activity. The conversion of these aromatic compounds is mainly an aerobic process because of the involvement of molecular oxygen in ring fission and as an electron acceptor. Recent literatures indicated that ring fission of monomers and obligomers mainly occurs in anaerobic environments through anaerobic respiration with nitrate, sulphate, carbon dioxide or carbonate as electron acceptors. These anaerobic processes will help to work out the better situation for bioremediation of contaminated environments. While there are plenty of efforts to reduce the release of these chemicals to the environment, already contaminated sites need to be remediated not only to restore the sites but to prevent the leachates spreading to nearby environment. Basically microorganisms are better candidates for breakdown of these compounds because of their wider catalytic mechanisms and the ability to act even in the absence of oxygen. These microbes can be grouped based on their energy mechanisms. Normally, the aerobic counterparts employ the enzymes like mono-and-dioxygenases. The end product is basically catechol, which further may be metabolised to CO2 by means of quinones reductases cycles. In the absense of reductases compounds, the reduced catechols tend to become oxidised to form many quinone compounds. The quinone products are more recalcitrant and lead to other aesthetic problems like colour in water, unpleasant odour, etc. On the contrary, in the reducing environment this process is prevented and in a cascade of pathways, the cleaved products are converted to acetyl co-A to be integrated into other central metabolite paths. The central metabolite of anaerobic degradation is invariably co-A thio-esters of benzoic acid or hydroxy benzoic acid. The benzene ring undergoes various substitution and addition reactions to form chloro-, nitro-, methyl- compounds

  17. "Carbo-aromaticity" and novel carbo-aromatic compounds.

    PubMed

    Cocq, Kévin; Lepetit, Christine; Maraval, Valérie; Chauvin, Remi

    2015-09-21

    While the concept of aromaticity is being more and more precisely delineated, the category of "aromatic compounds" is being more and more expanded. This is illustrated by an introductory highlight of the various types of "aromaticity" previously invoked, and by a focus on the recently proposed "aromatic character" of the "two-membered rings" of the acetylene and butatriene molecules. This serves as a general foundation for the definition of "carbo-aromaticity", the relevance of which is surveyed through recent results in the synthetic, physical, and theoretical chemistry of carbo-mers and in particular macrocyclic-polycyclic representatives constituting a natural family of "novel aromatic compounds". With respect to their parent molecules, carbo-mers are constitutionally defined as "carbon-enriched", and can also be functionally regarded as "π-electron-enriched". This is exemplified by recent experimental and theoretical results on functional, aromatic, rigid, σ,π-macrocyclic carbo-benzene archetypes of various substitution patterns, with emphasis on the quadrupolar pattern. For the purpose of comparison, several types of non-aromatic references of carbo-benzenes are then considered, i.e. freely rotating σ,π-acyclic carbo-n-butadienes and flexible σ-cyclic, π-acyclic carbo-cyclohexadienes, and to "pro-aromatic" congeners, i.e. rigid σ,π-macrocyclic carbo-quinoids. It is shown that functional carbo-mers are entering the field of "molecular materials" for properties such as linear or nonlinear optical properties (e.g. dichromism and two-photon absorption) and single molecule conductivity. Since total or partial carbo-mers of aromatic carbon-allotropes of infinite size such as graphene (graphynes and graphdiynes) and graphite ("graphitynes") have long been addressed at the theoretical or conceptual level, recent predictive advances on the electrical, optical and mechanical properties of such carbo-materials are surveyed. Very preliminary experimental results

  18. Biodegradation of Aromatic Compounds by Escherichia coli

    PubMed Central

    Díaz, Eduardo; Ferrández, Abel; Prieto, María A.; García, José L.

    2001-01-01

    Although Escherichia coli has long been recognized as the best-understood living organism, little was known about its abilities to use aromatic compounds as sole carbon and energy sources. This review gives an extensive overview of the current knowledge of the catabolism of aromatic compounds by E. coli. After giving a general overview of the aromatic compounds that E. coli strains encounter and mineralize in the different habitats that they colonize, we provide an up-to-date status report on the genes and proteins involved in the catabolism of such compounds, namely, several aromatic acids (phenylacetic acid, 3- and 4-hydroxyphenylacetic acid, phenylpropionic acid, 3-hydroxyphenylpropionic acid, and 3-hydroxycinnamic acid) and amines (phenylethylamine, tyramine, and dopamine). Other enzymatic activities acting on aromatic compounds in E. coli are also reviewed and evaluated. The review also reflects the present impact of genomic research and how the analysis of the whole E. coli genome reveals novel aromatic catabolic functions. Moreover, evolutionary considerations derived from sequence comparisons between the aromatic catabolic clusters of E. coli and homologous clusters from an increasing number of bacteria are also discussed. The recent progress in the understanding of the fundamentals that govern the degradation of aromatic compounds in E. coli makes this bacterium a very useful model system to decipher biochemical, genetic, evolutionary, and ecological aspects of the catabolism of such compounds. In the last part of the review, we discuss strategies and concepts to metabolically engineer E. coli to suit specific needs for biodegradation and biotransformation of aromatics and we provide several examples based on selected studies. Finally, conclusions derived from this review may serve as a lead for future research and applications. PMID:11729263

  19. Nucleophilic fluorination of aromatic compounds

    DOEpatents

    Satyamurthy, Nagichettiar; Barrio, Jorge R

    2014-03-18

    Iodylbenzene derivatives substituted with electron donating as well as electron withdrawing groups on the aromatic ring are used as precursors in aromatic nucleophilic substitution reactions. The iodyl group (IO.sub.2) is regiospecifically substituted by nucleophilic fluoride to provide the corresponding fluoroaryl derivatives. No-carrier-added [F-18]fluoride ion derived from anhydrous [F-18](F/Kryptofix, [F-18]CsF or a quaternary ammonium fluoride (e.g., Me.sub.4NF, Et.sub.4NF, n-Bu.sub.4NF, (PhCH.sub.2).sub.4NF) exclusively substitutes the iodyl moiety in these derivatives and provides high specific activity F-18 labeled fluoroaryl analogs. Iodyl derivatives of a benzothiazole analog and 6-iodyl-L-dopa derivatives have been synthesized as precursors and have been used in the preparation of no-carrier-added [F-18]fluorobenzothiazole as well as 6-[F-18]fluoro-L-dopa.

  20. Linear heterocyclic aromatic fluorescence compounds having various donor-acceptor spacers prepared by the combination of carbon-carbon bond and carbon-nitrogen bond cross-coupling reactions.

    PubMed

    Hu, Bin; Fu, Shu-Jun; Xu, Feng; Tao, Tao; Zhu, Hao-Yu; Cao, Kou-Sen; Huang, Wei; You, Xiao-Zeng

    2011-06-01

    A family of novel linear 1,10-phenanthroline-based (A-D-A-D-A) and oligothiophene-based (A-D-D-D-(D)-A) heterocyclic aromatic fluorescence compounds having N-containing imidazole and pyridine tails with effective π-conjugated systems, prepared by the combination of carbon-carbon (C-C) bond and carbon-nitrogen (C-N) bond cross-coupling reactions, is described. They have molecular lengths of more than 2.30 nm in the cases of 4, 6, 9, and 26, various D-A spacers, and certain N-coordination sites (phen, imidazole, and pyridine). X-ray single-crystal structures of 13 compounds reveal a variety of trans and cis configurations with different dihedral angles between adjacent aromatic heterocycles. Synthetic, computational, and spectral studies have been made to reveal the differences between cross-coupling approaches on the C-C bond and C-N bond formation as well as band gaps and energy levels and optical and electrochemical properties for related compounds. The influences of introducing a β-methyl group to the thiophene ring on reaction activity, solubility, and conformation of related compounds have also been discussed. PMID:21513323

  1. Overview of Polycyclic Aromatic Compounds (PAC)

    PubMed Central

    Achten, Christine; Andersson, Jan T.

    2015-01-01

    The chemical group of polycyclic aromatic compounds (PAC), including the better-known subgroup of polycyclic aromatic hydrocarbons (PAH) and the heterocyclic aromatic compounds (NSO-PAC, heterocycles), comprise several thousand individual compounds. It is hard to find a comprehensive overview in the literature of these PACs that includes a substantial amount of relevant properties. Here an attempt is made to summarize the most studied but also some less well-known PACs. In addition to basic data such as recommended names, abbreviations, CAS numbers, molecular formulas, chemical structures, and exact mono-isotopic molecular weights, physico-chemical properties taken from the literature like boiling points, vapor pressures, water solubilities, Henry's Law constants, n-octanol-water partition coefficients (log KOW), and pKa are summarized. Selected toxicological data are listed indicating carcinogenic and mutagenic activity or effects on different organisms. PAC nomenclature is a complex topic, so suggestions for practical use are made. Regarding available data, estimated (instead of measured) values should be used with caution because considerable deviations from experimentally determined values can occur. For an enhanced understanding of the behavior of single PACs in comparison with each other, some of the properties mentioned above are plotted vs. the number of rings or the degree of alkylation. Also, some physico-chemical data are correlated with different functional groups as substituents of the PAHs. This article reveals that rather little is known about the less common PACs, e.g., higher molecular weight compounds, alkylated or otherwise substituted aromatics, for instance, keto-, oxo-, amino-, nitro-, cyano-PAHs, or some heterocyclic aromatic compounds, including their derivatives. It mirrors the limited state of knowledge about the variety of PACs that do not belong to the 16 EPA PAHs. PMID:26823644

  2. Chemotaxis of Azospirillum species to aromatic compounds

    SciTech Connect

    Lopez-de-Victoria, G.; Lovell, C.R. )

    1993-09-01

    Azospirillum sspeciesare free-living nitrogen fixing bacteria commonly found in soils and in association with plant roots, including important agricultural crops. Rhizosphere colonization my Azospirillum species has been shown to stimulate growth of a variety of plant species. Chemotaxis is one of the properties which may contribute to survival, rhizosphere colonization and the initiation of mutualistic interactions by Azospirillum species. This study evaluates the chemotactic responses of three Azospirillum stains to a variety of aromatic compounds:benzoate, catechol, 4-HB, and PCA. Results indicate that the same aromatic substance can elicit different chemotactic responses from different Azospirillum species, and that Azospirillum can detect aromatic substrates at concentrations similar to those they encounter naturally. 36 refs., 1 fig., 6 tabs.

  3. Fluorescent aromatic sensors and their methods of use

    NASA Technical Reports Server (NTRS)

    Meador, Michael A. (Inventor); Tyson, Daniel S. (Inventor); Ilan, Ulvi F. (Inventor)

    2012-01-01

    Aromatic molecules that can be used as sensors are described. The aromatic sensors include a polycyclic aromatic hydrocarbon core with a five-membered imide rings fused to the core and at least two pendant aryl groups. The aromatic sensor molecules can detect target analytes or molecular strain as a result of changes in their fluorescence, in many cases with on-off behavior. Aromatic molecules that fluoresce at various frequencies can be prepared by altering the structure of the aromatic core or the substituents attached to it. The aromatic molecules can be used as sensors for various applications such as, for example, the detection of dangerous chemicals, biomedical diagnosis, and the detection of damage or strain in composite materials. Methods of preparing aromatic sensor molecules are also described.

  4. 40 CFR 721.750 - Aromatic amine compound.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 40 Protection of Environment 32 2013-07-01 2013-07-01 false Aromatic amine compound. 721.750... Substances § 721.750 Aromatic amine compound. (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance aromatic amine compound (PMN P-86-334) is subject to reporting...

  5. 40 CFR 721.875 - Aromatic nitro compound.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 40 Protection of Environment 31 2014-07-01 2014-07-01 false Aromatic nitro compound. 721.875... Substances § 721.875 Aromatic nitro compound. (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance aromatic nitro compound (PMN P-86-335) is subject to reporting...

  6. 40 CFR 721.875 - Aromatic nitro compound.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 40 Protection of Environment 30 2010-07-01 2010-07-01 false Aromatic nitro compound. 721.875... Substances § 721.875 Aromatic nitro compound. (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance aromatic nitro compound (PMN P-86-335) is subject to reporting...

  7. 40 CFR 721.875 - Aromatic nitro compound.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 40 Protection of Environment 32 2012-07-01 2012-07-01 false Aromatic nitro compound. 721.875... Substances § 721.875 Aromatic nitro compound. (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance aromatic nitro compound (PMN P-86-335) is subject to reporting...

  8. 40 CFR 721.750 - Aromatic amine compound.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 40 Protection of Environment 31 2011-07-01 2011-07-01 false Aromatic amine compound. 721.750... Substances § 721.750 Aromatic amine compound. (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance aromatic amine compound (PMN P-86-334) is subject to reporting...

  9. 40 CFR 721.875 - Aromatic nitro compound.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 40 Protection of Environment 32 2013-07-01 2013-07-01 false Aromatic nitro compound. 721.875... Substances § 721.875 Aromatic nitro compound. (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance aromatic nitro compound (PMN P-86-335) is subject to reporting...

  10. 40 CFR 721.875 - Aromatic nitro compound.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 40 Protection of Environment 31 2011-07-01 2011-07-01 false Aromatic nitro compound. 721.875... Substances § 721.875 Aromatic nitro compound. (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance aromatic nitro compound (PMN P-86-335) is subject to reporting...

  11. 40 CFR 721.750 - Aromatic amine compound.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 40 Protection of Environment 31 2014-07-01 2014-07-01 false Aromatic amine compound. 721.750... Substances § 721.750 Aromatic amine compound. (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance aromatic amine compound (PMN P-86-334) is subject to reporting...

  12. 40 CFR 721.750 - Aromatic amine compound.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 40 Protection of Environment 30 2010-07-01 2010-07-01 false Aromatic amine compound. 721.750... Substances § 721.750 Aromatic amine compound. (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance aromatic amine compound (PMN P-86-334) is subject to reporting...

  13. 40 CFR 721.750 - Aromatic amine compound.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 40 Protection of Environment 32 2012-07-01 2012-07-01 false Aromatic amine compound. 721.750... Substances § 721.750 Aromatic amine compound. (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance aromatic amine compound (PMN P-86-334) is subject to reporting...

  14. Transformations of Aromatic Compounds by Nitrosomonas europaea

    PubMed Central

    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 monooxygenase (AMO). AMO catalyzed alkyl substituent hydroxylations, styrene epoxidation, ethylbenzene desaturation to styrene, and aniline oxidation to nitrobenzene (and unidentified products). Alkyl substituents were preferred oxidation sites, but the ring was also oxidized to produce phenolic compounds from benzene, ethylbenzene, halobenzenes, phenol, and nitrobenzene. No carboxylic acids were identified. Ethylbenzene was oxidized via styrene to two products common also to oxidation of styrene; production of styrene is suggestive of an electron transfer mechanism for AMO. Iodobenzene and 1,2-dichlorobenzene were oxidized slowly to halophenols; 1,4-dichlorobenzene was not transformed. No 2-halophenols were detected as products. Several hydroxymethyl (-CH2OH)-substituted aromatics and p-cresol were oxidized by C2H2-treated cells to the corresponding aldehydes, benzaldehyde was reduced to benzyl alcohol, and o-cresol and 2,5-dimethylphenol were not depleted. PMID:16349282

  15. Metabolism of aromatic compounds by Caulobacter crescentus

    SciTech Connect

    Chatterjee, D.K.; Bourquin, A.W.

    1987-05-01

    Cultures of Caulobacter crescentus were found to grow on a variety of aromatic compounds. Degradation of benzoate, p-hydroxybenzoate, and phenol was found to occur via ..beta..-ketoadipate. The induction of degradative enzymes such as benzoate 1,2-dioxygenase, the ring cleavage enzyme catechol 1,2-dioxygenase, and cis,cis-muconate lactonizing enzyme appeared similar to the control mechanism present in Pseudomonas spp. Both benzoate 1,2-dioxygenase and catechol 1,2-dioxygenase had stringent specificities, as revealed by their action toward substituted benzoates and substituted catechols, respectively.

  16. Petroleum hydrocarbons, fluorescent aromatic compounds in fish bile and organochlorine pesticides from areas surrounding the spill of the Kab121 well, in the Southern Gulf of Mexico: a case study.

    PubMed

    Gold-Bouchot, G; Ceja-Moreno, V; Chan-Cocom, E; Zapata-Perez, O

    2014-01-01

    In October 2007, a light crude oil spill took place in the off shore Kab121 oil well, 32 km north of the mouth of the Grijalva River, Tabasco, Mexico. In order to estimate the possible effects of oil spill on the biota in the area surrounding the spilled well, the level of different fractions of petroleum hydrocarbons were measured in fish, as well as the concentration of some chlorinated hydrocarbons and PCBs. The organisms examined were cat fish (Ariopsis felis), in addition fluorescent aromatic compounds in bile, the contaminants above mentioned and their relationship with cyotochrome P-450 and Ethoxyresorufin-O-deethylase, Glutathion-S-Transferase and catalase activities in liver were determined. The concentration of most pollutants were low, except PAHs. Spatial distribution of these compounds, as well as most biomarkers, reflected the highest exposure of fish to pollutants in the area adjacent to well, as well as in the proximity of rivers. The profile of exposure to this environment was chronic in nature and not temporary. PMID:24579530

  17. Interstellar Polycyclic Aromatic Compounds and Astrophysics

    NASA Technical Reports Server (NTRS)

    Hudgins, Douglas M.; DeVincenzi, Donald (Technical Monitor)

    2001-01-01

    Over the past fifteen years, thanks to significant, parallel advancements in observational, experimental, and theoretical techniques, tremendous strides have been made in our understanding of the role polycyclic aromatic compounds (PAC) in the interstellar medium (ISM). Twenty years ago, the notion of an abundant population of large, carbon rich molecules in the ISM was considered preposterous. Today, the unmistakable spectroscopic signatures of PAC - shockingly large molecules by previous interstellar chemistry standards - are recognized throughout the Universe. In this paper, we will examine the interstellar PAC model and its importance to astrophysics, including: (1) the evidence which led to inception of the model; (2) the ensuing laboratory and theoretical studies of the fundamental spectroscopic properties of PAC by which the model has been refined and extended; and (3) a few examples of how the model is being exploited to derive insight into the nature of the interstellar PAC population.

  18. Reductive carbonylation of aromatic nitro compounds

    SciTech Connect

    Wehman, P.; Kamer, P.C.J.; Leeuwen, P.W.N.M. van

    1995-12-31

    In the reductive carbonylation of aromatic nitro compounds carbamates and isocyanates are prepared through a direct reaction between the nitro group and CO under the influence of a catalyst. This route avoids the major disadvantages of the traditional process for the production of the industrially important isocyanates and carbamates. The authors have developed a stable, active, and rather selective homogeneous palladium catalyst for the reductive carbonylation of the nitro substrate. Best results were obtained with Pd-phenanthroline complexes in which the ligands bear moderately donating substituents. Noncoordinating anions in the catalyst complex are clearly preferable. The highest activity was reached with the Pd(4,7-Me{sub 2}-1,10-phen){sub 2}(OTf){sub 2} catalyst complex (t.o.f. = 311 mol/mol/h, selectivity toward the desired carbamate = 84%). With the Pd(1,10-phenanthroline){sub 2}(OTf){sub 2} catalyst complex, the authors studied the scope of the reaction in order to prepare a wide range of functionalized carbamates for the fine chemistry. During this study, it was found that a remarkable improvement of the catalytic activity and selectivity on addition of a benzoic acid (t.o.f. > 365 mol/mol/h, selectivity toward carbamate = 94%). In the presence of 4-chlorobenzoic acid even aromatic dinitro compounds could be converted easily, resulting in the best results reported ever for the conversion of 1,4-dinitrobenzene into the corresponding dicarbamate (t.o.f. = 73 mol/mol/h, selectivity toward the dicarbamate = 86%).

  19. Fluorescence Spectroscopy of Gas-phase Polycyclic Aromatic Hydrocarbons

    NASA Technical Reports Server (NTRS)

    Thomas, J. D.; Witt, A. N.

    2006-01-01

    The purpose of this investigation was to produce fluorescence spectra of polycyclic aromatic hydrocarbon (PAH) molecules in the gas-phase for comparison with blue luminescence (BL) emission observed in astrophysical sources Vijh et al. (2004, 2005a,b). The BL occurs roughly from 350 to 450 nm, with a sharp peak near 380 nm. PAHs with three to four rings, e.g. anthracene and pyrene, were found to produce luminescence in the appropriate spectral region, based on existing studies. Relatively few studies of the gas-phase fluorescence of PAHs exist; those that do exist have dealt primarily with the same samples commonly available for purchase such as pyrene and anthracene. In an attempt to understand the chemistry of the nebular environment we also obtained several nitrogen substituted PAHs from our colleagues at NASA Ames. In order to simulate the astrophysical environment we also took spectra by heating the PAHs in a flame. The flame environment counteracts the formation of eximers and permits the spectroscopy of free-flying neutral molecules. Experiments with coal tar demonstrate that fluorescence spectroscopy reveals primarily the presence of the smallest molecules, which are most abundant and which possess the highest fluorescence efficiencies. One gas-phase PAH that seems to fit the BL spectrum most closely is phenanthridine. In view of the results from the spectroscopy of coal tar, a compound containing a mixture of PAHs ranging from small to very large PAH molecules, we can not preclude the presence of larger PAHs in interstellar sources exhibiting BL.

  20. Anaerobic Catabolism of Aromatic Compounds: a Genetic and Genomic View

    PubMed Central

    Carmona, Manuel; Zamarro, María Teresa; Blázquez, Blas; Durante-Rodríguez, Gonzalo; Juárez, Javier F.; Valderrama, J. Andrés; Barragán, María J. L.; García, José Luis; Díaz, Eduardo

    2009-01-01

    Summary: Aromatic compounds belong to one of the most widely distributed classes of organic compounds in nature, and a significant number of xenobiotics belong to this family of compounds. Since many habitats containing large amounts of aromatic compounds are often anoxic, the anaerobic catabolism of aromatic compounds by microorganisms becomes crucial in biogeochemical cycles and in the sustainable development of the biosphere. The mineralization of aromatic compounds by facultative or obligate anaerobic bacteria can be coupled to anaerobic respiration with a variety of electron acceptors as well as to fermentation and anoxygenic photosynthesis. Since the redox potential of the electron-accepting system dictates the degradative strategy, there is wide biochemical diversity among anaerobic aromatic degraders. However, the genetic determinants of all these processes and the mechanisms involved in their regulation are much less studied. This review focuses on the recent findings that standard molecular biology approaches together with new high-throughput technologies (e.g., genome sequencing, transcriptomics, proteomics, and metagenomics) have provided regarding the genetics, regulation, ecophysiology, and evolution of anaerobic aromatic degradation pathways. These studies revealed that the anaerobic catabolism of aromatic compounds is more diverse and widespread than previously thought, and the complex metabolic and stress programs associated with the use of aromatic compounds under anaerobic conditions are starting to be unraveled. Anaerobic biotransformation processes based on unprecedented enzymes and pathways with novel metabolic capabilities, as well as the design of novel regulatory circuits and catabolic networks of great biotechnological potential in synthetic biology, are now feasible to approach. PMID:19258534

  1. Structure-Activity Relationships in Nitro-Aromatic Compounds

    NASA Astrophysics Data System (ADS)

    Vogt, R. A.; Rahman, S.; Crespo-Hernández, C. E.

    Many nitro-aromatic compounds show mutagenic and carcinogenic properties, posing a potential human health risk. Despite this potential health hazard, nitro-aromatic compounds continue to be emitted into ambient air from municipal incinerators, motor vehicles, and industrial power plants. As a result, understanding the structural and electronic factors that influence mutagenicity in nitro-aromatic compounds has been a long standing objective. Progress toward this goal has accelerated over the years, in large part due to the synergistic efforts among toxicology, computational chemistry, and statistical modeling of toxicological data. The concerted influence of several structural and electronic factors in nitro-aromatic compounds makes the development of structure-activity relationships (SARs) a paramount challenge. Mathematical models that include a regression analysis show promise in predicting the mutagenic activity of nitro-aromatic compounds as well as in prioritizing compounds for which experimental data should be pursued. A major challenge of the structure-activity models developed thus far is their failure to apply beyond a subset of nitro-aromatic compounds. Most quantitative structure-activity relationship papers point to statistics as the most important confirmation of the validity of a model. However, the experimental evidence shows the importance of the chemical knowledge in the process of generating models with reasonable applicability. This chapter will concisely summarize the structural and electronic factors that influence the mutagenicity in nitro-aromatic compounds and the recent efforts to use quantitative structure-activity relationships to predict those physicochemical properties.

  2. Fluorescence method for enzyme analysis which couples aromatic amines with aromatic aldehydes

    DOEpatents

    Smith, Robert E. [557 Escondido Cir., Livermore, CA 94550; Dolbeare, Frank A. [5178 Diane La., Livermore, CA 94550

    1980-10-21

    Analysis of proteinases is accomplished using conventional amino acid containing aromatic amine substrates. Aromatic amines such as 4-methoxy-2-naphthylamine (4M2NA), 2-naphthylamine, aminoisophthalic acid dimethyl ester, p-nitroaniline, 4-methoxy-1-aminofluorene and coumarin derivatives resulting from enzymatic hydrolysis of the substrate couples with aromatic aldehydes such as 5-nitrosalicylaldehyde (5-NSA), benzaldehyde and p-nitrobenzaldehyde to produce Schiff-base complexes which are water insoluble. Certain Schiff-base complexes produce a shift from blue to orange-red (visible) fluorescence. Such complexes are useful in the assay of enzymes.

  3. Fluorescence method for enzyme analysis which couples aromatic amines with aromatic aldehydes

    DOEpatents

    Smith, Robert E.; Dolbeare, Frank A.

    1979-01-01

    Analysis of proteinases is accomplished using conventional amino acid containing aromatic amine substrates. Aromatic amines such as 4-methoxy-2-naphthylamine (4M2NA), 2-naphthylamine, aminoisophthalic acid dimethyl ester, p-nitroaniline, 5-methoxy-1-aminofluorene and coumarin derivatives resulting from enzymatic hydrolysis of the substrate couples with aromatic aldehydes such as 5-nitrosalicylaldehyde (5-NSA), benzaldehyde and p-nitrobenzaldehyde to produce Schiff-base complexes which are water insoluble. Certain Schiff-base complexes produce a shift from blue to orange-red (visible) fluorescence. Such complexes are useful in the assay of enzymes.

  4. Fluorescence method for enzyme analysis which couples aromatic amines with aromatic aldehydes

    DOEpatents

    Smith, R.E.; Dolbeare, F.A.

    1980-10-21

    Analysis of proteinases is accomplished using conventional amino acid containing aromatic amine substrates. Aromatic amines such as 4-methoxy-2-naphthylamine (4M2NA), 2-naphthylamine, aminoisophthalic acid dimethyl ester, p-nitroaniline, 4-methoxy-1-aminofluorene and coumarin derivatives resulting from enzymatic hydrolysis of the substrate couples with aromatic aldehydes such as 5-nitrosalicylaldehyde (5-NSA), benzaldehyde and p-nitrobenzaldehyde to produce Schiff-base complexes which are water insoluble. Certain Schiff-base complexes produce a shift from blue to orange-red (visible) fluorescence. Such complexes are useful in the assay of enzymes. No Drawings

  5. Assessing Uncertainty of Interspecies Correlation Estimation Models for Aromatic Compounds

    EPA Science Inventory

    We developed Interspecies Correlation Estimation (ICE) models for aromatic compounds containing 1 to 4 benzene rings to assess uncertainty in toxicity extrapolation in two data compilation approaches. ICE models are mathematical relationships between surrogate and predicted test ...

  6. Enzymatic Conversion of Aromatic Compounds Obtained from Crop Residues

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Biomass obtained from crop residues and the related processing wastes typically contain minor amounts of aromatic compounds such as ferulic and p-coumaric acids. These compounds occur as esters and ethers associated with plant cell wall structures and as components of lignin. These compounds exhibit...

  7. Terahertz Spectroscopy of Biochars and Related Aromatic Compounds

    NASA Astrophysics Data System (ADS)

    Lepodise, L. M.; Horvat, J.; Lewis, R. A.

    2016-07-01

    A recent application of terahertz spectroscopy is to biochar, the agricultural charcoal produced by pyrolysis of various organic materials. Biochars simultaneously improve soil fertility and assist in carbon sequestration. Terahertz spectroscopy allows different biochars to be distinguished. However, the origin of the absorption features observed has not been clear. Given that biochar-based fertilizers are rich in aromatic compounds, we have investigated simple aromatic compounds as an approach to unravelling the complex biochar spectrum.

  8. Aromatic metabolism of filamentous fungi in relation to the presence of aromatic compounds in plant biomass.

    PubMed

    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 obstacles in the biofuel/biochemical production process and therefore microbial degradation of lignin is receiving a great deal of attention. Fungi are the main degraders of plant biomass, and in particular the basidiomycete white rot fungi are of major importance in converting plant aromatics due to their ability to degrade lignin. However, the aromatic monomers that are released from lignin and other aromatic compounds of plant biomass are toxic for most fungi already at low levels, and therefore conversion of these compounds to less toxic metabolites is essential for fungi. Although the release of aromatic compounds from plant biomass by fungi has been studied extensively, relatively little attention has been given to the metabolic pathways that convert the resulting aromatic monomers. In this review we provide an overview of the aromatic components of plant biomass, and their release and conversion by fungi. Finally, we will summarize the applications of fungal systems related to plant aromatics. PMID:25911233

  9. Heterocyclic compounds and aromatic diglycosides from Bretschneidera sinensis.

    PubMed

    Liu, Chun-Mei; Li, Bo; Shen, Yun-Heng; Zhang, Wei-Dong

    2010-09-24

    Two new heterocyclic compounds, bretschneiderazines A and B (1, 2), three new aromatic diglycosides, bretschneiderosides A-C (3-5), and three known aromatic diglycosides, 6-8, were isolated from Bretschneidera sinensis. The structure of bretschneiderazine A (1) was confirmed by single-crystal X-ray diffraction analysis. Bretschneiderazine A (1) showed moderate activity against the NCI-H446 cell line. PMID:20722446

  10. Photoinduced electron transfer and fluorescence mechanisms in covalently linked polynuclear aromatic-nucleotide complexes

    SciTech Connect

    Geacintov, N.E.; Mao, Bing; Zhao, Rushen; Chen, Junxin; Liu, Tong Ming; Ya, Nai-Qi; France, L.L.; Sutherland, J.D.

    1992-04-01

    The fluorescence of polycyclic aromatic hydrocarbon-nucleic acid complexes is quenched by photoinduced electron transfer mechanisms in aqueous solutions at ambient temperatures. These effects are illustrated with the biologically important compound benzo[a]pyrene-7,8-diol-9,10-epoxide (BPDE), a mutagenic and carcinogenic metabolite of the environmental pollutant benzo[a]pyrene, which forms covalent mutagenic lesions with 2{prime}-deoxyguanosine (dG) residues in DNA. The dependence of the fluroescence yeild and fluorescence decay times of the covalent model adduct (+)-trans-BPDE-N{sup 2}-dG as a function of temperature and methanol/water composition are described. Because of the sensitivity of the fluorescence of the pyrenyl residue to the polarity of the microenvironment, the magnitude of the fluorescence yield can be used to distinguish between highly hydrophobic (e.g. intercalation) and other more solvent-exposed BPDE-nucleic acid binding sites.

  11. Photoinduced electron transfer and fluorescence mechanisms in covalently linked polynuclear aromatic-nucleotide complexes

    SciTech Connect

    Geacintov, N.E.; Mao, Bing; Zhao, Rushen; Chen, Junxin; Liu, Tong Ming; Ya, Nai-Qi . Dept. of Chemistry); France, L.L.; Sutherland, J.D. )

    1992-01-01

    The fluorescence of polycyclic aromatic hydrocarbon-nucleic acid complexes is quenched by photoinduced electron transfer mechanisms in aqueous solutions at ambient temperatures. These effects are illustrated with the biologically important compound benzo(a)pyrene-7,8-diol-9,10-epoxide (BPDE), a mutagenic and carcinogenic metabolite of the environmental pollutant benzo(a)pyrene, which forms covalent mutagenic lesions with 2{prime}-deoxyguanosine (dG) residues in DNA. The dependence of the fluroescence yeild and fluorescence decay times of the covalent model adduct (+)-trans-BPDE-N{sup 2}-dG as a function of temperature and methanol/water composition are described. Because of the sensitivity of the fluorescence of the pyrenyl residue to the polarity of the microenvironment, the magnitude of the fluorescence yield can be used to distinguish between highly hydrophobic (e.g. intercalation) and other more solvent-exposed BPDE-nucleic acid binding sites.

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

    NASA Astrophysics Data System (ADS)

    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

  13. The oxidation degradation of aromatic compounds

    NASA Technical Reports Server (NTRS)

    Brezinsky, Kenneth; Glassman, Irvin

    1987-01-01

    A series of experiments were conducted which focused on understanding the role that the O atom addition to aromatic rings plays in the oxidation of benzene and toluene. Flow reactor studies of the oxidation of toluene gave an indication of the amount of O atoms available during an oxidation and the degree to which the O atom adds to the ring. Flow reactor studies of the oxidation of toluene and benzene to which NO2 was added, have shown that NO2 appears to suppress the formation of O atoms and consequently reduce the amount of phenols and cresols formed by O atom addition. A high temperature pyrolysis study of phenol has confirmed that the major decomposition products are carbon monoxide and cyclopentadiene. A preliminary value for the overall decomposition rate constant was also obtained.

  14. Airborne Exposures to Polycyclic Aromatic Compounds Among Workers in Asphalt Roofing Manufacturing Facilities.

    PubMed

    Trumbore, David C; Osborn, Linda V; Johnson, Kathleen A; Fayerweather, William E

    2015-01-01

    We studied exposure of 151 workers to polycyclic aromatic compounds and asphalt emissions during the manufacturing of asphalt roofing products-including 64 workers from 10 asphalt plants producing oxidized, straight-run, cutback, and wax- or polymer-modified asphalts, and 87 workers from 11 roofing plants producing asphalt shingles and granulated roll roofing. The facilities were located throughout the United States and used asphalt from many refiners and crude oils. This article helps fill a gap in exposure data for asphalt roofing manufacturing workers by using a fluorescence technique that targets biologically active 4-6 ring polycyclic aromatic compounds and is strongly correlated with carcinogenic activity in animal studies. Worker exposures to polycyclic aromatic compounds were compared between manufacturing plants, at different temperatures and using different raw materials, and to important external benchmarks. High levels of fine limestone particulate in the plant air during roofing manufacturing increased polycyclic aromatic compound exposure, resulting in the hypothesis that the particulate brought adsorbed polycyclic aromatic compounds to the worker breathing zone. Elevated asphalt temperatures increased exposures during the pouring of asphalt. Co-exposures in these workplaces which act as confounders for both the measurement of total organic matter and fluorescence were detected and their influence discussed. Exposures to polycyclic aromatic compounds in asphalt roofing manufacturing facilities were lower than or similar to those reported in hot-mix paving application studies, and much below those reported in studies of hot application of built-up roofing asphalt. These relatively low exposures in manufacturing are primarily attributed to air emission controls in the facilities, and the relatively moderate temperatures, compared to built-up roofing, used in these facilities for oxidized asphalt. The exposure to polycyclic aromatic compounds was a very

  15. Global atmospheric budget of simple monocyclic aromatic compounds

    NASA Astrophysics Data System (ADS)

    Cabrera-Perez, David; Taraborrelli, Domenico; Sander, Rolf; Pozzer, Andrea

    2016-06-01

    The global atmospheric budget and distribution of monocyclic aromatic compounds is estimated, using an atmospheric chemistry general circulation model. Simulation results are evaluated with an ensemble of surface and aircraft observations with the goal of understanding emission, production and removal of these compounds.Anthropogenic emissions provided by the RCP database represent the largest source of aromatics in the model (≃ 23 TgC year-1) and biomass burning from the GFAS inventory the second largest (≃ 5 TgC year-1). The simulated chemical production of aromatics accounts for ≃ 5 TgC year-1. The atmospheric burden of aromatics sums up to 0.3 TgC. The main removal process of aromatics is photochemical decomposition (≃ 27 TgC year-1), while wet and dry deposition are responsible for a removal of ≃ 4 TgC year-1.Simulated mixing ratios at the surface and elsewhere in the troposphere show good spatial and temporal agreement with the observations for benzene, although the model generally underestimates mixing ratios. Toluene is generally well reproduced by the model at the surface, but mixing ratios in the free troposphere are underestimated. Finally, larger discrepancies are found for xylenes: surface mixing ratios are not only overestimated but also a low temporal correlation is found with respect to in situ observations.

  16. Monitoring of fuel consumption and aromatics formation in a kerosene spray flame as characterized by fluorescence spectroscopy.

    PubMed

    Allouis, C; Apicella, B; Barbella, R; Beretta, F; Ciajolo, A; Tregrossi, A

    2003-06-01

    The large presence of aromatic compounds in distillate fossil fuels should allow, in line of principle, to follow the fuel consumption and/or the presence of unburned fuel in a high temperature environment like a burner or the exhaust of combustion systems by exploiting the high fluorescence emission of aromatic fuel components. To this aim an UV-excited fluorescence source has to be used since the aromatic fuel components are strongly fluorescing in the UV region of the emission spectrum. In this work UV-excited laser induced fluorescence (LIF) diagnostics was applied to spray flames of kerosene in order to follow the fuel consumption and the formation of aromatic species. A strong UV signal was detected in the spray region of the flame that presented a shape similar to that found in the LIF spectra preliminary measured on the cold spray and in the room-temperature fluorescence of fuel solutions. The decrease of UV signal along the spray flame region was associated to the consumption of the fuel, but more difficult seems to be the attribution of a broad visible emission, that is present downstream of the flame. The visible emission feature could be assigned to flame-formed PAH species contained in the high molecular weight species, hypothesizing that their fluorescence spectra are shifted toward the visible for effect of the high temperature flame environment. PMID:12718975

  17. [Formations and reactions of aromatic furazan compounds].

    PubMed

    Hasegawa, M; Takabatake, T; Miyazawa, T

    2001-06-01

    A reaction from various kinds of nitroquinoline with hydroxylamine in potassium hydroxide alkalinity produced a novel product, furazanoquinoline, besides the known amino derivatives. The products obtained were furazano [3,4-f] quinoline (5) from 5-nitroquinoline (1) and 6-nitroquinoline (6), and furazano [3,4-h] quinoline (10) from 7-nitroquinoline (8) and 8-nitroquinoline (11). The reaction mechanism was believed to be as shown in Figs. 2 and 3. The photoreaction of benzofuroxan (19) in acetonitrile containing a little water, under a high pressure mercury lamp, produced 1H-azepine-2,7-dione (20), while under irradiation using a low pressure lamp, 6H-furazano [4,5-c] carbazole-3-oxide (21) and compound 20 were obtained. Then the photoproduct 20 produced photodimer 22 by irradiation in acetonitrile: water (9:1, v/v) using a high or low pressure mercury lamp, while photolysis with alkali proceeded as in the photoreaction of N-alkylimide to give 7-hydroxy-1H-azepine-2-one (23). When pyrido [2,3-c] furoxan (24) was irradiated in acetonitrile containing a little water with a low pressure mercury lamp, 3-nitro-2-pyridone (25) was obtained. When compound 24 was irradiated in the presence of morpholine with a low pressure mercury lamp in an argon atmosphere, 6-morpholinopyridine 2,3-dioxime (26) was produced. Quinoxaline 1,4-dioxide derivatives (31, 33), phenazine 5,10-dioxide derivatives (36, 37) and pyrido [2,3-b] pyrazine derivatives (38, 39) were synthesized from the corresponding furoxan catalyzed by silica gel or molecular sieves, and their antibacterial properties were evaluated. The results of antibacterial screening tests in vitro, revealed strong activity against Bacteroides fragilis. PMID:11433773

  18. [Spectrophotometric determination of aromatic amino compounds with J-acid].

    PubMed

    Yin, Xiao-hang; Shi, Wen-jian; Shen, Xin; Ma, Jun-tao; Li, Liang

    2015-01-01

    The problems such as chromogenic reaction selectivity, reaction rate, sensitivity and water-solubility of azo compounds were considered. The molecular structures of coupling components were theoretically designed and screened in the present research The reaction conditions and methods of chromogenic reaction were investigated. J-Acid (2-amino-5-naphthol-7-sulfonic acid) as a coupling reagent to determine aromatic amino compounds was established. In the presence of potassium bromide, at room temperature, nitrite reacted with aromatic amino compounds in the medium of thin hydrochloric acid. Then diazonium salt reacted with J-Acid in the aqueous solution of sodium carbonate, forming coloured azo dye, which had a maximum adsorption at 480 nm. The molar adsorption coeffcients of aniline, 4-aminobenzene sulfonic acid and 1-naphthylamine were 3. 95 X 10(4), 3. 24 X 10(4) and 3. 91 X 10(4) L . mol-1 . cm-1 , respectively. Experimental results showed that common coexisting ions on the surface water did not affect the results of determination. J-Acid of spectrophotometry was used to determine the samples of Shanghai Fu Xing Dao canal. Meanwhile, recovery experiments by standard addition method were done. Experiment results showed that the recoveries of aniline were in the range of 98. 5%-102. 1%, and RSD was 2. 08%. J-Acid is a common organic reagent. It is soluble in water and low volatile, and its toxicity is much lower than N-ethylenediamine. spectrophotometric determination of aromatic amino compounds by J-Acid has the advantage of high sensitivity, good selectivity, simple rapid operation and accurate results, and thus it can be used for the determination of trace aromatic amino compounds in the environmental water. PMID:25993847

  19. 40 CFR 721.785 - Halogenated alkane aromatic compound (generic name).

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 40 Protection of Environment 30 2010-07-01 2010-07-01 false Halogenated alkane aromatic compound... Specific Chemical Substances § 721.785 Halogenated alkane aromatic compound (generic name). (a) Chemical... as a halogenated alkane aromatic compound (PMN P-94-1747) is subject to reporting under this...

  20. 40 CFR 721.785 - Halogenated alkane aromatic compound (generic name).

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 40 Protection of Environment 32 2012-07-01 2012-07-01 false Halogenated alkane aromatic compound... Specific Chemical Substances § 721.785 Halogenated alkane aromatic compound (generic name). (a) Chemical... as a halogenated alkane aromatic compound (PMN P-94-1747) is subject to reporting under this...

  1. 40 CFR 721.785 - Halogenated alkane aromatic compound (generic name).

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 40 Protection of Environment 32 2013-07-01 2013-07-01 false Halogenated alkane aromatic compound... Specific Chemical Substances § 721.785 Halogenated alkane aromatic compound (generic name). (a) Chemical... as a halogenated alkane aromatic compound (PMN P-94-1747) is subject to reporting under this...

  2. 40 CFR 721.9620 - Aromatic sulfonic acid compound with amine.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 40 Protection of Environment 32 2012-07-01 2012-07-01 false Aromatic sulfonic acid compound with... Specific Chemical Substances § 721.9620 Aromatic sulfonic acid compound with amine. (a) Chemical substance... aromatic sulfonic acid compound with amine (PMN P-93-832) is subject to reporting under this section...

  3. 40 CFR 721.9620 - Aromatic sulfonic acid compound with amine.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 40 Protection of Environment 31 2011-07-01 2011-07-01 false Aromatic sulfonic acid compound with... Specific Chemical Substances § 721.9620 Aromatic sulfonic acid compound with amine. (a) Chemical substance... aromatic sulfonic acid compound with amine (PMN P-93-832) is subject to reporting under this section...

  4. 40 CFR 721.785 - Halogenated alkane aromatic compound (generic name).

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 40 Protection of Environment 31 2011-07-01 2011-07-01 false Halogenated alkane aromatic compound... Specific Chemical Substances § 721.785 Halogenated alkane aromatic compound (generic name). (a) Chemical... as a halogenated alkane aromatic compound (PMN P-94-1747) is subject to reporting under this...

  5. 40 CFR 721.9620 - Aromatic sulfonic acid compound with amine.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 40 Protection of Environment 30 2010-07-01 2010-07-01 false Aromatic sulfonic acid compound with... Specific Chemical Substances § 721.9620 Aromatic sulfonic acid compound with amine. (a) Chemical substance... aromatic sulfonic acid compound with amine (PMN P-93-832) is subject to reporting under this section...

  6. 40 CFR 721.785 - Halogenated alkane aromatic compound (generic name).

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 40 Protection of Environment 31 2014-07-01 2014-07-01 false Halogenated alkane aromatic compound... Specific Chemical Substances § 721.785 Halogenated alkane aromatic compound (generic name). (a) Chemical... as a halogenated alkane aromatic compound (PMN P-94-1747) is subject to reporting under this...

  7. 40 CFR 721.9620 - Aromatic sulfonic acid compound with amine.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 40 Protection of Environment 31 2014-07-01 2014-07-01 false Aromatic sulfonic acid compound with... Specific Chemical Substances § 721.9620 Aromatic sulfonic acid compound with amine. (a) Chemical substance... aromatic sulfonic acid compound with amine (PMN P-93-832) is subject to reporting under this section...

  8. 40 CFR 721.9620 - Aromatic sulfonic acid compound with amine.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 40 Protection of Environment 32 2013-07-01 2013-07-01 false Aromatic sulfonic acid compound with... Specific Chemical Substances § 721.9620 Aromatic sulfonic acid compound with amine. (a) Chemical substance... aromatic sulfonic acid compound with amine (PMN P-93-832) is subject to reporting under this section...

  9. Amination of electrophilic aromatic compounds by vicarious nucleophilic substitution

    SciTech Connect

    Mitchell, A.R.; Pagoria, P.F.; Schmidt, R.D.

    2000-05-30

    The present invention relates to a process to aminate electrophilic aromatic compounds by vicarious nucleophilic substitution of hydrogen using quaternary hydrazinium salts. The use of trialkylhydrazinium halide, e.g., trimethylhydrazinium iodide, as well as hydroxylamine, alkoxylamines, and 4-amino-1,2,4-triazole to produce aminated aromatic structures, such as 1,3-diamino-2,4,6-trinitrobenzene (DATB), 1,3,5-triamino-2,4,6-trinitrobenzene (TATB) and 3,5-diamino-2,4,6-trinitrotoluene (DATNT), is described. DATB and TATB are useful insensitive high explosives. TATB is also used for the preparation of benzenehexamine, a starting material for the synthesis of novel materials (optical imaging devices, liquid crystals, ferromagnetic compounds).

  10. Amination of electrophilic aromatic compounds by vicarious nucleophilic substitution

    DOEpatents

    Mitchell, Alexander R.; Pagoria, Philip F.; Schmidt, Robert D.

    2000-01-01

    The present invention relates to a process to aminate electrophilic aromatic compounds by vicarious nucleophilic substitution of hydrogen using quaternary hydrazinium salts. The use of trialkylhydrazinium halide, e.g., trimethylhydrazinium iodide, as well as hydroxylamine, alkoxylamines, and 4-amino-1,2,4-triazole to produce aminated aromatic structures, such as 1,3-diamino-2,4,6-trinitrobenzene (DATB), 1,3,5-triamino-2,4,6-trinitrobenzene (TATB) and 3,5-diamino-2,4,6-trinitrotoluene (DATNT), is described. DATB and TATB are useful insensitive high explosives. TATB is also used for the preparation of benzenehexamine, a starting material for the synthesis of novel materials (optical imaging devices, liquid crystals, ferromagnetic compounds).

  11. Aromatic fluorine compounds. VII. Replacement of aromatic -Cl and -NO2 groups by -F

    USGS Publications Warehouse

    Finger, G.C.; Kruse, C.W.

    1956-01-01

    Replacement of -Cl by -F in aryl chlorides with potassium fluoride has been extended from 2,4-dinitrochlorobenzene to less activated halides by the use of non-aqueous solvents, especially dimethylformamide (DMF) and dimethyl sulfoxide (DMSO). Also replacement of -NO2 by -F in substituted nitrobenzenes was studied in DMF. As a direct result of this study, many aromatic fluorine compounds can now be obtained by a relatively simple synthetic route.

  12. DNA nanostructures based biosensor for the determination of aromatic compounds.

    PubMed

    Gayathri, S Baby; Kamaraj, P; Arthanareeswari, M; Devikala, S

    2015-10-15

    Graphite electrode was modified using multi-walled carbon nanotubes (MWCNT), chitosan (CS), glutaraldehyde (GTA) and DNA nanostructures (nsDNA). DNA nanostructures of 50 nm in size were produced from single DNA template sequence using a simple two step procedure and were confirmed using TEM and AFM analysis. The modified electrode was applied to the electrochemical detection of aromatic compounds using EIS. The modified electrode was characterized using differential pulse voltammetry (DPV), electrochemical impedance spectroscopy (EIS) and cyclic voltammetry (CV). For comparison, electrochemical results derived from single stranded (50 bp length) and double stranded (50 bp length) DNA based biosensors were used. The results indicate that the modified electrode prior to nsDNA immobilization provides a viable platform that effectively promotes electron transfer between nsDNA and the electrode. The mode of binding between the nsDNA and aromatic compounds was investigated using EIS, indicating that the dominant interaction is non-covalent. nsDNA based biosensor was observed to act as an efficient biosensor in selective and sensitive identification of aromatic compounds. PMID:25982727

  13. Fluorescent compounds for plastic scintillation applications

    SciTech Connect

    Pla-Dalmau, A.; Bross, A.D.

    1994-04-01

    Several 2-(2{prime}-hydroxyphenyl)benzothiazole, -benzoxazole, and -benzimidazole derivatives have been prepared. Transmittance, fluorescence, light yield, and decay time characteristics of these compounds have been studied in a polystyrene matrix and evaluated for use in plastic scintillation detectors. Radiation damage studies utilizing a {sup 60}C source have also been performed.

  14. Detection of polycyclic aromatic hydrocarbons (PAHs) in raw menhaden fish oil using fluorescence spectroscopy: Method development.

    PubMed

    Pena, Edwin A; Ridley, Lauren M; Murphy, Wyatt R; Sowa, John R; Bentivegna, Carolyn S

    2015-09-01

    Raw menhaden fish oil was developed for biomonitoring polycyclic aromatic hydrocarbons (PAHs) using fluorescence spectroscopy. Menhaden (Genus Brevoortia) were collected in 2010 and/or 2011 from Delaware Bay, New Jersey, USA; James River, Virginia, USA; Vermillion Bay, Louisiana, USA (VBLA); and Barataria Bay, Louisiana, USA (BBLA). Barataria Bay, Louisiana received heavy oiling from the Deepwater Horizon oil spill. Method development included determining optimal wavelengths for PAH detection, fish oil matrix interferences, and influence of solvent concentration on extraction. Results showed that some fish oils contained high molecular weight PAH-like compounds in addition to other fluorescent compounds such as albumin and vitamin A and vitamin E. None of these naturally occurring compounds interfered with detection of high molecular weight PAHs. However, data suggested that the lipid component of fish oil was altering fluorescence spectra by supporting the formation of PAH excimers. For example, the most intense excitation wavelength for hydroxypyrene shifted from Ex285/Em430 to Ex340/Em430. Comparison of Deepwater Horizon crude oil and fish oil spectra indicated that some fish oils contained crude oil-like PAHs. Using wavelengths of Ex360/Em430, fish oil concentrations were calculated as 3.92 μg/g, 0.61 μg/g, and 0.14 μg/g for a Delaware Bay sample, BBLA 2011, and VBLA 2011, respectively. Overall, these results supported using menhaden fish oil to track PAH exposures spatially and temporally. PMID:25867932

  15. Interactions between manganese oxides and multiple-ringed aromatic compounds

    SciTech Connect

    Whelan, G. ); Sims, R.C. . Dept. of Civil and Environmental Engineering)

    1992-08-01

    Objective is to determine whether Mn reductive dissolution can oxidize multiple-ringed aromatics, such as PAHs, in an oxic environment Research indicated that certain PAHs (eg, dihydrodiols and diones that form free-radical intermediates) are susceptible to oxidation and polymerization. Over 14 days, 83, 76, 54, 70, and 20% of the Mn was reduced by 2,3-, 1,3-, and 1,4-naphthalenediol, quinizarin, and 1,4-naphthoquinone, respectively. 100, 100, and 65% of the first three PAHs were oxidized, respectively. Aromatics with diol functional groups were more easily oxidized than those with only dione groups. Relatively insoluble compounds like quinizarin can be oxidized; insoluble ''humic-like'' material precipitated, indicating a polymerization-humification process. Results suggest that electron transfer/organic release from the oxide surface is the rate-limiting step.

  16. Interactions between manganese oxides and multiple-ringed aromatic compounds

    SciTech Connect

    Whelan, G.; Sims, R.C.

    1992-08-01

    Objective is to determine whether Mn reductive dissolution can oxidize multiple-ringed aromatics, such as PAHs, in an oxic environment? Research indicated that certain PAHs (eg, dihydrodiols and diones that form free-radical intermediates) are susceptible to oxidation and polymerization. Over 14 days, 83, 76, 54, 70, and 20% of the Mn was reduced by 2,3-, 1,3-, and 1,4-naphthalenediol, quinizarin, and 1,4-naphthoquinone, respectively. 100, 100, and 65% of the first three PAHs were oxidized, respectively. Aromatics with diol functional groups were more easily oxidized than those with only dione groups. Relatively insoluble compounds like quinizarin can be oxidized; insoluble ``humic-like`` material precipitated, indicating a polymerization-humification process. Results suggest that electron transfer/organic release from the oxide surface is the rate-limiting step.

  17. A Novel Hydrolytic Dehalogenase for the Chlorinated Aromatic Compound Chlorothalonil▿

    PubMed Central

    Wang, Guangli; Li, Rong; Li, Shunpeng; Jiang, Jiandong

    2010-01-01

    Dehalogenases play key roles in the detoxification of halogenated aromatics. Interestingly, only one hydrolytic dehalogenase for halogenated aromatics, 4-chlorobenzoyl-coenzyme A (CoA) dehalogenase, has been reported. Here, we characterize another novel hydrolytic dehalogenase for a halogenated aromatic compound from the 2,4,5,6-tetrachloroisophthalonitrile (chlorothalonil)-degrading strain of Pseudomonas sp. CTN-3, which we have named Chd. Chd catalyzes a hydroxyl substitution at the 4-chlorine atom of chlorothalonil. The metabolite of the Chd dehalogenation, 4-hydroxy-trichloroisophthalonitrile, was identified by reverse-phase high-performance liquid chromatography (HPLC), tandem mass spectrometry (MS/MS), and nuclear magnetic resonance (NMR). Chd dehalogenates chlorothalonil under anaerobic and aerobic conditions and does not require the presence of cofactors such as CoA and ATP. Chd contains a putative conserved domain of the metallo-β-lactamase superfamily and shows the highest identity with several metallohydrolases (24 to 29%). Chd is a monomer (36 kDa), and the isoelectric point (pI) of Chd is estimated to be 4.13. Chd has a dissociation constant (Km) of 0.112 mM and an overall catalytic rate (kcat) of 207 s−1 for chlorothalonil. Chd is completely inhibited by 1,10-phenanthroline, diethyl pyrocarbonate, and N-bromosuccinic acid. Site-directed mutagenesis of Chd revealed that histidines 128 and 157, serine 126, aspartates 45, 130 and 184, and tryptophan 241 were essential for the dehalogenase activity. Chd differs from other reported hydrolytic dehalogenases based on the analysis of amino acid sequences and catalytic mechanisms. This study provides an excellent dehalogenase candidate for mechanistic study of hydrolytic dehalogenation of halogenated aromatic compound. PMID:20363940

  18. Development of genetically engineered bacteria for production of selected aromatic compounds

    DOEpatents

    Ward, Thomas E.; Watkins, Carolyn S.; Bulmer, Deborah K.; Johnson, Bruce F.; Amaratunga, Mohan

    2001-01-01

    The cloning and expression of genes in the common aromatic pathway of E. coli are described. A compound for which chorismate, the final product of the common aromatic pathway, is an anabolic intermediate can be produced by cloning and expressing selected genes of the common aromatic pathway and the genes coding for enzymes necessary to convert chorismate to the selected compound. Plasmids carrying selected genes of the common aromatic pathway are also described.

  19. FISH BILIARY POLYCYCLIC AROMATIC HYDROCARBON METABOLITES ESTIMATED BY FIXED-WAVELENGTH FLUORESCENCE: COMPARISON WITH HPLC-FLUORESCENT DETECTION

    EPA Science Inventory

    Fixed wavelength fluorescence (FF) was compared to high-performance liquid chromatography with fluorescence detection (HPLC-F) as an estimation of polycyclic aromatic hydrocarbon (PAH) exposure to fish. Two excitation/emission wavelength pairs were used to measure naphthalene- an...

  20. Reactivity of monocyclic aromatic compounds under hydrothermal conditions

    NASA Astrophysics Data System (ADS)

    McCollom, T. M.; Seewald, J. S.; Simoneit, B. R. T.

    2001-02-01

    Monocyclic aromatic compounds (MAC) represent a significant fraction of the total organic carbon in many geologic environments such as hydrothermal systems and petroleum reservoirs, yet the factors that control their abundance in these environments remain highly uncertain. In order to evaluate whether aqueous reactions involving MAC have a significant impact on their occurrence, laboratory experiments were conducted to observe the reactivity of several simple MAC under hydrothermal conditions that included the presence of mineral redox buffers. Aqueous solutions of individual MAC were heated at 300 to 330°C and 350 bar in flexible gold reaction vessels with titanium fittings. Toluene in aqueous solution was found to gradually decompose during heating to form primarily benzene plus CO 2, indicating the decomposition proceeded by an oxidative decarboxylation pathway. The rate of this reaction was enhanced by the presence of dissolved sulfur compounds and relatively oxidizing conditions, suggesting that intermediate oxidation state sulfur compounds (such as thiosulfate or polythionates) could play a role in promoting the reaction by facilitating the transfer of electrons among reactants. Benzoic acid decomposed rapidly to benzene plus CO 2, suggesting that formation of benzoic acid is the rate-limiting step in the overall conversion of toluene to benzene. Both benzene and phenol were found to be essentially unreactive. An assessment of the reaction products was performed to evaluate whether reactions among MAC attained metastable thermodynamic equilibrium. The results of this assessment, however, were equivocal, with some observations suggesting approach to thermodynamic equilibrium while other data indicate that criteria to demonstrate equilibrium were not met. The laboratory results demonstrate that aqueous reactions can play a role in controlling the abundance of aromatic compounds in geologic environments.

  1. Method of upgrading oils containing hydroxyaromatic hydrocarbon compounds to highly aromatic gasoline

    DOEpatents

    Baker, E.G.; Elliott, D.C.

    1993-01-19

    The present invention is a multi-stepped method of converting an oil which is produced by various biomass and coal conversion processes and contains primarily single and multiple ring hydroxyaromatic hydrocarbon compounds to highly aromatic gasoline. The single and multiple ring hydroxyaromatic hydrocarbon compounds in a raw oil material are first deoxygenated to produce a deoxygenated oil material containing single and multiple ring aromatic compounds. Then, water is removed from the deoxygenated oil material. The next step is distillation to remove the single ring aromatic compounds as gasoline. In the third step, the multiple ring aromatics remaining in the deoxygenated oil material are cracked in the presence of hydrogen to produce a cracked oil material containing single ring aromatic compounds. Finally, the cracked oil material is then distilled to remove the single ring aromatics as gasoline.

  2. Pore size dynamics in interpenetrated metal organic frameworks for selective sensing of aromatic compounds.

    PubMed

    Myers, Matthew; Podolska, Anna; Heath, Charles; Baker, Murray V; Pejcic, Bobby

    2014-03-28

    The two-fold interpenetrated metal-organic framework, [Zn2(bdc)2(dpNDI)]n (bdc=1,4-benzenedicarboxylate, dpNDI=N'N'-di(4-pyridyl)-1,4,5,8-naphthalenediimide) can undergo structural re-arrangement upon adsorption of chemical species changing its pore structure. For a competitive binding process with multiple analytes of different sizes and geometries, the interpenetrated framework will adopt a conformation to maximize the overall binding interactions. In this study, we show for binary mixtures that there is a high selectivity for the larger methylated aromatic compounds, toluene and p-xylene, over the small non-methylated benzene. The dpNDI moiety within [Zn2(bdc)2(dpNDI)]n forms an exciplex with these aromatic compounds. The emission wavelength is dependent on the strength of the host-guest CT interaction allowing these compounds to be distinguished. We show that the sorption selectivity characteristics can have a significant impact on the fluorescence sensor response of [Zn2(bdc)2(dpNDI)]n towards environmentally important hydrocarbons based contaminants (i.e., BTEX, PAH). PMID:24636414

  3. [Synthesis and spectrum of novel pyrazoline fluorescent compounds].

    PubMed

    Liu, Qiu-Jun; Gao, Lei; Wang, Lei; Xie, Zhi-Yuan; Li, Dong-Feng

    2009-10-01

    Pyrazoline derivatives have been used widely in dyeing industry as fluorescent whitening agents due to their excellent capability. According to Schellhammer theory of the relation between chemical structure and fluorescent quality, six new fluorescent compounds were designed and synthesized which contained the benzothiazole group in the 1-pyrazoline, the indole group in the 3-pyrazoline and the derivatives of phenyl in the 5-pyrazoline. The structure of target compounds was confirmed by IR, 1H NMR, MS and elementary analysis. The fluorescence spectra showed that these compounds had good fluorescence. They could absorb ultraviolet light at near 353 nm. The fluorescence maximum emission wavelengths were about 430-443 nm. It was a kind of promising fluorescence compounds. The largest fluorescence emission wavelength and the fluorescence intensity were related to the substituted group of the compounds. When the 6-Br group was introduced into benzothiazole, the fluorescence emission wavelength exhibited a blue shift, and the fluorescence intensity increased. Otherwise, the CH3 group was introduced into benzothiazole, the fluorescence emission wavelength red-shift occurred, and the intensity was lower. The fluorescence quantum yield of the compounds was little affected by the substituted group and polarity of the solvent The relative fluorescence intensity and fluorescence quantum yield were not directly related. PMID:20038066

  4. Gas and Particulate Sampling of Airborne Polycyclic Aromatic Compounds

    SciTech Connect

    Lane, D.A.; Gundel, L.A.

    1995-10-01

    The denuder surfaces of the gas and particle (GAP) sampler (developed at the Atmospheric Environment Service of Environment Canada) have been modified by coating with XAD-4 resin, using techniques developed at Lawrence Berkeley National Laboratory (LBNL) for the lower capacity integrated organic vapor/particle sampler (IOVPS). The resulting high capacity integrated organic gas and particle sampler (IOGAPS) has been operated in ambient air at 16.7 L min{sup -1} for a 24-hour period in Berkeley, California, USA. Simultaneous measurements were made at the same collection rate with a conventional sampler that used a filter followed by two sorbent beds. Gas and particle partition measurements were determined for 13 polycyclic aromatic hydrocarbons (PAH) ranging from 2-ring to 6-ring species. The IOGAPS indicated a higher particle fraction of these compounds than did the conventional sampler, suggesting that the conventional sampler suffered from 'blow-off' losses from the particles collected on the filter.

  5. Metal-Free Reduction of Aromatic Nitro Compounds to Aromatic Amines with B2pin2 in Isopropanol.

    PubMed

    Lu, Hongtao; Geng, Zhiyue; Li, Jingya; Zou, Dapeng; Wu, Yusheng; Wu, Yangjie

    2016-06-01

    A metal-free reduction of aromatic nitro compounds to the corresponding amines has been achieved by a combination of B2pin2 and KOtBu in isopropanol. A series of nitro compounds containing various reducible functional groups were chemoselectively reduced in good to excellent yields. PMID:27214590

  6. Metabolism of Multiple Aromatic Compounds in Corn Stover Hydrolysate by Rhodopseudomonas palustris.

    PubMed

    Austin, Samantha; Kontur, Wayne S; Ulbrich, Arne; Oshlag, J Zachary; Zhang, Weiping; Higbee, Alan; Zhang, Yaoping; Coon, Joshua J; Hodge, David B; Donohue, Timothy J; Noguera, Daniel R

    2015-07-21

    Lignocellulosic biomass hydrolysates hold great potential as a feedstock for microbial biofuel production, due to their high concentration of fermentable sugars. Present at lower concentrations are a suite of aromatic compounds that can inhibit fermentation by biofuel-producing microbes. We have developed a microbial-mediated strategy for removing these aromatic compounds, using the purple nonsulfur bacterium Rhodopseudomonas palustris. When grown photoheterotrophically in an anaerobic environment, R. palustris removes most of the aromatics from ammonia fiber expansion (AFEX) treated corn stover hydrolysate (ACSH), while leaving the sugars mostly intact. We show that R. palustris can metabolize a host of aromatic substrates in ACSH that have either been previously described as unable to support growth, such as methoxylated aromatics, and those that have not yet been tested, such as aromatic amides. Removing the aromatics from ACSH with R. palustris, allowed growth of a second microbe that could not grow in the untreated ACSH. By using defined mutants, we show that most of these aromatic compounds are metabolized by the benzoyl-CoA pathway. We also show that loss of enzymes in the benzoyl-CoA pathway prevents total degradation of the aromatics in the hydrolysate, and instead allows for biological transformation of this suite of aromatics into selected aromatic compounds potentially recoverable as an additional bioproduct. PMID:26121369

  7. Method of upgrading oils containing hydroxyaromatic hydrocarbon compounds to highly aromatic gasoline

    DOEpatents

    Baker, Eddie G.; Elliott, Douglas C.

    1993-01-01

    The present invention is a multi-stepped method of converting an oil which is produced by various biomass and coal conversion processes and contains primarily single and multiple ring hydroxyaromatic hydrocarbon compounds to highly aromatic gasoline. The single and multiple ring hydroxyaromatic hydrocarbon compounds in a raw oil material are first deoxygenated to produce a deoxygenated oil material containing single and multiple ring aromatic compounds. Then, water is removed from the deoxygenated oil material. The next step is distillation to remove the single ring aromatic compouns as gasoline. In the third step, the multiple ring aromatics remaining in the deoxygenated oil material are cracked in the presence of hydrogen to produce a cracked oil material containing single ring aromatic compounds. Finally, the cracked oil material is then distilled to remove the single ring aromatics as gasoline.

  8. Amino Acids, Aromatic Compounds, and Carboxylic Acids: How Did They Get Their Common Names?

    ERIC Educational Resources Information Center

    Leung, Sam H.

    2000-01-01

    Surveys the roots of the common names of organic compounds most likely to be encountered by undergraduate organic chemistry students. Includes information for 19 amino acids, 17 aromatic compounds, and 21 carboxylic acids. (WRM)

  9. 40 CFR 721.775 - Brominated aromatic com-pound (generic name).

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 40 Protection of Environment 30 2010-07-01 2010-07-01 false Brominated aromatic com-pound (generic name). 721.775 Section 721.775 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED... Specific Chemical Substances § 721.775 Brominated aromatic com-pound (generic name). (a)...

  10. Neural networks as a tool to classify compounds according to aromaticity criteria.

    PubMed

    Alonso, Mercedes; Herradón, Bernardo

    2007-01-01

    Aromaticity is a fundamental concept in chemistry, with many theoretical and practical implications. Although most organic compounds can be categorized as aromatic, non-aromatic, or antiaromatic, it is often difficult to classify borderline compounds as well as to quantify this property. Many aromaticity criteria have been proposed, although none of them gives an entirely satisfactory solution. The inability to fully arrange organic compounds according to a single criterion arises from the fact that aromaticity is a multidimensional phenomenon. Neural networks are computational techniques that allow one to treat a large amount of data, thereby reducing the dimensionality of the input set to a bidimensional output. We present the successful applications of Kohonen's self-organizing maps to classify organic compounds according to aromaticity criteria, showing a good correlation between the aromaticity of a compound and its placement in a particular neuron. Although the input data for the training of the network were different aromaticity criteria (stabilization energy, diamagnetic susceptibility, NICS, NICS(1), and HOMA) for five-membered heterocycles, the method can be extended to other organic compounds. Some useful features of this method are: 1) it is very fast, requiring less than one minute of computational time to place a new compound in the map; 2) the placement of the different compounds in the map is conveniently visualized; 3) the position of a compound in the map depends on its aromatic character, thus allowing us to establish a quantitative scale of aromaticity, based on Euclidean distances between neurons, 4) it has predictive power. Overall, the results reported herein constitute a significant contribution to the longstanding debate on the quantitative treatment of aromaticity. PMID:17323387

  11. Quenching of fluorescence of phenolic compounds and modified humic acids by cadmium ions.

    PubMed

    Tchaikovskaya, O N; Nechaev, L V; Yudina, N V; Mal'tseva, E V

    2016-08-01

    The interaction of a number of phenolic compounds, being 'model fragments' of humic acids, with cadmium ions was investigated. The fluorescence quenching method was used to determine the complexation constants of these compounds with cadmium ions. It was established that bonding of phenolic compounds by cadmium ions at рН 7 is weak and reaches a maximum value of 15% for interaction with resorcinol. It was demonstrated that modification of humic acids by the mechanoactivation method increases by three times bonding of cadmium ions, which is caused by strengthening the acid properties of carboxyl and hydroxyl groups at the aromatic ring. Copyright © 2016 John Wiley & Sons, Ltd. PMID:26729402

  12. Correlation and prediction of adsorption capacity and affinity of aromatic compounds on carbon nanotubes.

    PubMed

    Wu, Wenhao; Yang, Kun; Chen, Wei; Wang, Wendi; Zhang, Jie; Lin, Daohui; Xing, Baoshan

    2016-01-01

    Adsorption of 22 nonpolar and polar aromatic compounds on 10 carbon nanotubes (CNTs) with various diameters, lengths and surface oxygen-containing group contents was investigated to develop predictive correlations for adsorption, using the isotherm fitting of Polanyi theory-based Dubinin-Ashtakhov (DA) model. Adsorption capacity of aromatic compounds on CNTs is negatively correlated with melting points of aromatic compounds, and surface oxygen-containing group contents and surface area ratios of mesopores to total pores of CNTs, but positively correlated with total surface area of CNTs. Adsorption affinity is positively correlated with solvatochromic parameters of aromatic compounds, independent of tube lengths and surface oxygen-containing group contents of CNTs, but negatively correlated with surface area ratios of mesopores to total pores of CNTs. The correlations of adsorption capacity and adsorption affinity with properties of both aromatic compounds and CNTs clearly have physical significance, can be used successfully with DA model to predict adsorption of aromatic compounds on CNTs from the well-known physiochemical properties of aromatic compounds (i.e., solvatochromic parameters, melting points) and CNTs (i.e., surface area and total acidic group contents), and thus can facilitate the environmental application of CNTs as sorbents and environmental risk assessment of both aromatic contaminants and CNTs. PMID:26521219

  13. Effects of aromatic compounds on antennal responses and on the pheromone-binding proteins of the gypsy moth (Lymantria dispar).

    PubMed

    Gong, Yongmei; Plettner, Erika

    2011-03-01

    Female gypsy moths emit a pheromone, (+)-disparlure, which the males follow until they locate the emitter. The male moths' antennae are covered with innervated sensory hairs, specialized in detection of the pheromone. The neurons in these sensory hairs are bathed by a solution rich in pheromone-binding protein (PBP). PBPs are soluble proteins that bind the pheromone and other odorants reversibly with variable thermodynamic and kinetic selectivity and are essential for olfactory responses. Here, we have studied the interaction between 2 gypsy moth PBPs with aromatic compounds that modulate the responses of male moth antennae to (+)-disparlure. The aromatic compounds do not elicit responses by themselves, but when administered together with pheromone, they inhibit, enhance, or prolong the electrophysiological response to the pheromone. Three interactions between the compounds and PBPs were studied: 1) the equilibrium binding of the compounds by themselves to the PBPs, 2) the equilibrium binding of the compounds in the presence of pheromone or a fluorescent reporter ligand, and 3) the effect of the compounds on the conformation of the pheromone-PBP complex. A subset of compounds causes a prolongation of the electroantennogram response, and from this study, we conclude that these compounds follow a structure-activity pattern and stabilize a particular conformer of the PBPs that appears to activate the olfactory response. PMID:21159920

  14. Effects of polyhalogenated aromatic compounds on porphyrin metabolism.

    PubMed Central

    Hill, R H

    1985-01-01

    Heme production is a vital metabolic process that occurs in the bone marrow and liver. Porphyrins are unused by-products of this biosynthetic process and normally occur in urine and other body fluids in low concentrations. Various disorders can disrupt the heme biosynthetic process, causing greater quantities of porphyrins in urine. The porphyrias are a group of diseases characterized by excessive porphyrins and other precursors in urine. Porphyrias may be either hereditary or acquired through exposure to certain drugs or chemicals. Porphyria cutanea tarda (PCT) is the disease associated with exposure to polyhalogenated aromatic compounds. The urinary porphyrin pattern is of great value in diagnosing PCT and defining the etiology of the disease. As this liver disease from chemical damage develops, the urinary pattern progressively changes. With the development of a rapid and sensitive high-performance liquid chromatography analysis, urinary porphyrin patterns can be easily monitored. All free porphyrin acids can be quantitatively analyzed in less than 15 min. In our studies of groups exposed to porphyrinogenic chemicals, we have not observed clear differences in the urinary porphyrin patterns of cases when compared with carefully selected controls. In animal studies, however, PCT was clearly associated with polybrominated biphenyl exposure. Future evaluation of the utility of urinary porphyrin patterns as a diagnostic tool will require a cohort that has received a recent, well-documented exposure and a comparable control population. Assay of erythrocyte uroporphyrinogen decarboxylase activity will also be needed to define the form of the PCT. PMID:4029097

  15. Redox Switching of Orthoquinone-Containing Aromatic Compounds with Hydrogen and Oxygen Gas.

    PubMed

    Urakawa, Kazuki; Sumimoto, Michinori; Arisawa, Mitsuhiro; Matsuda, Masaki; Ishikawa, Hayato

    2016-06-20

    Unique redox switching of orthoquinone-containing pentacyclic aromatic compounds with molecular hydrogen and oxygen in the presence of a palladium nanoparticle catalyst (SAPd) is disclosed. These molecules were predicted by in silico screening before synthesis. Efficient protocols for the synthesis of orthoquinone-containing aromatic compounds by palladium-mediated homocoupling and the benzoin condensation reaction were developed. Clear switching between orthoquinone and aromatic hydroquinone compounds was observed on the basis of their photoluminescence properties. Furthermore, the twist strain of the orthoquinone moiety could induce dramatic changes in color and emission. PMID:27145376

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

    DOEpatents

    Googin, John M.; Napier, John M.; Travaglini, Michael A.

    1983-01-01

    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 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.

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

    DOEpatents

    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.

  18. Self-Assembly of New Arene-Ruthenium Rectangles Containing Triptycene Building Block and Their Application in Fluorescent Detection of Nitro Aromatics

    PubMed Central

    Dubey, Abhishek; Mishra, Anurag; Min, Jin Wook; Lee, Min Hyung; Kim, Hyunuk; Stang, Peter J.; Chi, Ki-Whan

    2014-01-01

    A suite of two new tetraruthenium metallarectangles 5 and 6 have been obtained from [2 + 2] self-assemblies between dipyridylethynyltriptycene 2 and one of the two dinuclear arene ruthenium clips, [Ru2 (μ-η4-OO∩OO) (η6-p-cymene)2][OTf]2 ; (OO∩OO = oxalate 3; 6,11-dihydroxy-5,12-naphthacenedionato (dotq) 4; OTf = triflate). These molecular rectangles are fully characterized by 1H NMR spectroscopy, electrospray mass spectrometry. A single crystal of 6 was suitable for X-ray diffraction structural characterization. These new metallarectangles showed fluorescence behavior in solution, have been examined for emission quenching effects with various aromatic compounds, and show high quenching selectivity and sensitivity towards nitroaromatics, particularly picric acid and trinitrotoluene. Excited-state charge transfer from the rectangles to nitro aromatic substrates can be used to develop selective fluorescent sensors for nitro aromatics. PMID:26321767

  19. Fluorescence, Absorption, and Excitation Spectra of Polycyclic Aromatic Hydrocarbons as a Tool for Quantitative Analysis

    ERIC Educational Resources Information Center

    Rivera-Figueroa, A. M.; Ramazan, K. A.; Finlayson-Pitts, B. J.

    2004-01-01

    A quantitative and qualitative study of the interplay between absorption, fluorescence, and excitation spectra of pollutants called polycyclic aromatic hydrocarbons (PAHs) is conducted. The study of five PAH displays the correlation of the above-mentioned properties along with the associated molecular changes.

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

    ERIC Educational Resources Information Center

    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…

  1. METHODOLOGY FOR DETERMINATION OF POLYCYCLIC AROMATIC HYDROCARBONS AND OTHER SEMIVOLATILE ORGANIC COMPOUNDS IN HOUSE DUST

    EPA Science Inventory

    Analytical methods were validated to determine polycyclic aromatic hydrocarbons (PAH) and other semivolatile organic compounds in house dust. e also examined the storage stability of three potential markers (solanesol, nicotine, and continine) for particulate-phase environmental ...

  2. Binding phenomena and fluorescence quenching. II: Photophysics of aromatic residues and dependence of fluorescence spectra on protein conformation

    NASA Astrophysics Data System (ADS)

    Callis, Patrik R.

    2014-12-01

    The three amino acids with aromatic ring side chains-phenylalanine (Phe), tyrosine (Tyr), and especially tryptophan (Trp) have played a long and productive role in helping unlock the secrets of protein behavior by optical spectroscopy (absorption, fluorescence, circular dichroism, etc.) In principle, an appropriately placed Trp will undergo fluorescence wavelength and/or intensity changes upon whatever functional process a protein performs. Although perceived to be enigmatic and not well understood, Trp is arguably now better understood than many of the extrinsic probes currently in use. Basic principles of intrinsic tryptophan fluorescence quenching and wavelength shifts in proteins are presented, with strong emphasis on the importance of electrostatics. The condensed description of findings from recent experiments and simulations of tryptophan fluorescence and intrinsic quenching in proteins is designed to help authors in planning and interpreting experimental results of ligand binding studies.

  3. [Health effect of volatile aldehyde compounds in photocatalytic oxidation of aromatics compounds].

    PubMed

    Zhao, Wei-rong; Liao, Qiu-wen; Yang, Ya-nan; Dai, Jiu-song

    2013-05-01

    Photocatalytic oxidation (PCO) of toluene and benzaldehyde in indoor air by N doped TiO2 (N-TiO2) was conducted under UV irradiation of 254 nm. The intermediates were identified and monitored on real-time by proton transfer reaction-mass spectrometry. The health risks of PCO of toluene and benzaldehyde were assessed based on health risk influence index (eta). Results indicated that both the conversion rate and mineralization rate of toluene and benzaldehyde were relatively high, however, the volatile aldehyde compounds (VAs), including acetaldehyde and formaldehyde generated from ring-opening, significantly influenced the health risks of PCO of toluene and benzaldehyde. Acetaldehyde played a crucial role on health risks, which was inclined to desorb from the surface of catalysts, accumulate in gas-phase, and increase the health risks of PCO of the aromatic compounds. The concentration of formaldehyde kept stable at a relatively low level, however its impact cannot be neglected. In the PCO process of toluene and benzaldehyde, eta reached the maximum values of 8 499.68 and 21.43, with the eta(VAs), contribution of VAs to the health risk influence index of outlet, reaching 99.3% and 98.3%, respectively. The average values of eta in the PCO process of 30 min were 932.86 and 8.52, and for which eta(VAs), reached 98.5% and 98.0%, respectively. When PCO of toluene and benzaldehyde reached steady state, eta were 236.09 and 2.30, and eta(VAs) reached 97.9% and 97.8%, respectively. Hence, eta(VAs), can be taken as a characteristic parameter in assessment of health risks of PCO of aromatic compounds. PMID:23914541

  4. Aromatic fumaronitrile core-based donor-linker-acceptor-linker-donor (D-pi-A-pi-D) compounds: synthesis and photophysical properties.

    PubMed

    Panthi, Krishna; Adhikari, Ravi M; Kinstle, Thomas H

    2010-04-01

    A new class of aromatic fumaronitrile core-based compounds with different donors and linkers has been synthesized and well characterized. Compounds 1 and 2 have indole and 2-phenylindole groups as electron donors, respectively. Compounds 3 and 4 have a diphenylamino group as the electron donor, and compound 5 has a 3,6-di-tert-butylcarbazole group as an electron donor. These compounds absorb in the blue-to-green region and emit in the blue-to-red region depending on the electron donor, linker, and solvents. The quantum yields of fluorescence of these compounds in solution are measured and found to be moderate, but in solid states, they are high. These compounds display strong emission solvatochromism that is reflected by a large shift in their fluorescence emission maxima on changing the solvents. This change is accompanied by a successive decrease in fluorescence intensity. The fluorescence lifetimes of these compounds are measured in different solvent and found to vary from <1 to 7 ns. Optical switching of these compounds with solvents, concentration, and excitation energy have been studied. The correlation between the functional group and optical properties has been established to some extent. The ability of these compounds to function as colorimetric and luminescence pH sensors is demonstrated with color changes and luminescence switching upon the addition of trifluoroacetic acid. The potentiality of these compounds for application in optoelectronics has been optically assessed. PMID:20235549

  5. The potential production of aromatic compounds in flowers of Vanda tricolor

    NASA Astrophysics Data System (ADS)

    Darmasiwi, Sari; Indriani, Vitri; Innata, Dita; Semiarti, Endang

    2015-09-01

    Vanda tricolor is a famous natural orchid that has beautiful flowers with fragrance, therefore analysis of aromatic compounds of this orchid are important. The objective of this research was to isolate and identify the aromatic compounds of Vanda tricolor flower. The flower petals were picked at various developmental stages (0,4,7, and 10 days of flower opened) at 12.00 noon. It was then extracted using solvent extraction method and enfleurage method. The hexane:acetone (9:1) extract was considered as concrete extract, while some parts of concrete that were further extracted with ethanol, considered as absolute extract. The olive oil extract was considered as enfleurage extract. Those extracts were then evaporated using nitrogen gas, and analyzed by GC/MS (GC/MS-QP 2010S Shimadzu, Agilent HP-5 MS UI column, 30 m ID length: 0.25 mm, Helium gas carrier). The results showed that aromatic compounds composition in Vanda tricolor flower extracts were consisted of fatty acid derivates, monoterpenoids, sesquiterpenoids, benzenoids, phenylpropanoids, hydrocarbons and other oxygenated compounds. The highest diversity of aromatic compounds were found at the 10th days after floral opened, and the sensory test among those 3 (three) extracts showed that the absolute extract had more similarity with the original flower scent profile rather than the other extracts. This research showed that Vanda tricolor has potential production of aromatic compounds which was different compare to another species of Vanda.

  6. Pioneering Metal-Free Oxidative Coupling Strategy of Aromatic Compounds Using Hypervalent Iodine Reagents.

    PubMed

    Kita, Yasuyuki; Dohi, Toshifumi

    2015-10-01

    We started our hypervalent iodine research about 30 years ago in the mid-1980s. We soon successfully developed the single-electron-transfer oxidation ability of a hypervalent iodine reagent, specifically, phenyliodine(III) bis(trifluoroacetate) (PIFA), toward aromatic rings of phenyl ethers for forming aromatic cation radicals. This was one of the exciting and unexpected events in our research studies so far, and the discovery was reported in 1991. It also led to the next challenge, developing the metal-free oxidative couplings for C-H functionalizations and direct couplings between the C-H bonds of valuable aromatic compounds in organic synthesis. In order to realize the effective oxidative coupling, pioneering new aromatic ring activations was essential and several useful methodologies have been found for oxidizable arenes. The achievements regarding this objective obtained in our continuous research are herein summarized with classification of the aromatic ring activation strategies. PMID:26223195

  7. A review of the selective catalytic reduction of aromatic nitro compounds into aromatic amines, isocyanates, carbamates, and ureas using CO

    SciTech Connect

    Tafesh, A.M.; Weiguny, J.

    1996-09-01

    Although the use of CO as a reductant had been in the past confined to few reactions, its use in organic synthesis, especially in the reductive carbonylation of nitro aromatics and the oxidative carbonylation of aromatic amines, has increased dramatically. Since the discovery of CO-induced reduction of nitro groups, there has been a wide spread increase of interest in the application and mechanistic understanding of this reaction. In a major review published in 1988 it was noted, that in practice no studies of the mechanism of N-carbonylation of aromatic nitro compounds with alcohols leading to carbamates have been carried out. This review clearly shows a major change since that publication. Indeed, metal-catalyzed reductive carbonylation of nitro aromatics using CO as reducing agent has been in the past 10 years the subject of intense investigation both in academia and in the chemical industry. Several articles and reviews have covered the subject up to the late 1980s. The authors will concentrate on more recent literature, but sometimes older data will be used to establish an understanding of these reactions. 127 refs.

  8. SOLVENT-FREE REDUCTION OF AROMATIC NITRO COMPOUNDS WITH ALUMINA-SUPPORTED HYDRAZINE UNDER MICROWAVE IRRADIATION

    EPA Science Inventory

    In a solvent-free microwave-expedited process, aromatic nitro compounds are readily reduced to the corresponding amino compounds in good yield with hydrazine hydrate supported on alumina in presence of FeCl3, 6H2), Fe(III) oxide hydroxide or Fe(III) oxides.

  9. Biodegradation of Various Aromatic Compounds by Enriched Bacterial Cultures: Part A-Monocyclic and Polycyclic Aromatic Hydrocarbons.

    PubMed

    Oberoi, Akashdeep Singh; Philip, Ligy; Bhallamudi, S Murty

    2015-08-01

    Present study focused on the screening of bacterial consortium for biodegradation of monocyclic aromatic hydrocarbon (MAH) and polycyclic aromatic hydrocarbons (PAHs). Target compounds in the present study were naphthalene, acenaphthene, phenanthrene (PAHs), and benzene (MAH). Microbial consortia enriched with the above target compounds were used in screening experiments. Naphthalene-enriched consortium was found to be the most efficient consortium, based on its substrate degradation rate and its ability to degrade other aromatic pollutants with significantly high efficiency. Substrate degradation rate with naphthalene-enriched culture followed the order benzene > naphthalene > acenaphthene > phenanthrene. Chryseobacterium and Rhodobacter were discerned as the predominant species in naphthalene-enriched culture. They are closely associated to the type strain Chryseobacterium arthrosphaerae and Rhodobacter maris, respectively. Single substrate biodegradation studies with naphthalene (PAH) and benzene (MAH) were carried out using naphthalene-enriched microbial consortium (NAPH). Phenol and 2-hydroxybenzaldehyde were identified as the predominant intermediates during benzene and naphthalene degradation, respectively. Biodegradation of toluene, ethyl benzene, xylene, phenol, and indole by NAPH was also investigated. Monod inhibition model was able to simulate biodegradation kinetics for benzene, whereas multiple substrate biodegradation model was able to simulate biodegradation kinetics for naphthalene. PMID:26054614

  10. Determination of aromatic compounds in water by solid phase microextraction and ultraviolet absorption spectroscopy. 1. Methodology

    SciTech Connect

    Wittkamp, B.L.; Hawthorne, S.B.; Tilotta, D.C.

    1997-03-15

    A simple method is described for determining aromatic compounds (i.e., benzene, toluene, ethylbenzene, etc.) in water that combines solid phase microextraction (SPME) and ultraviolet (UV) absorption spectroscopy. The extraction medium consists of a small `chip` of poly(dimethylsiloxane) (total volume of nearly 80 {mu}L) that is immersed in a water sample contaminated with an aromatic compound. Equilibrium is first allowed to establish between the analyte in the water and the extraction medium, and the concentration of the aromatic compound is then determined directly in the sorbent chip by UV spectroscopy. Calibration information on this new method was obtained for 11 aromatic compounds commonly found in unleaded gasoline (e.g., benzene, toluene, naphthalene, etc). It was found that equilibrium is established in the range of 30-50 min, with the exception of 1-methylnaphthalene and naphthalene, which equilibrated within 100 min. Detection limits for the aromatic compounds at their equilibration times range from 0.40 to 12 ppb except for benzene (97 ppb). Relative standard deviations of the SPME-UV measurements are 3-12%. 17 refs., 3 figs., 5 tabs.

  11. Identification of nonhydrocarbon aromatic compounds in the gas oil fraction of Kuwait petroleum

    SciTech Connect

    Ijam, M.J.; Arif, S.F. )

    1992-01-01

    The amounts of individual components in the nonhydrocarbon aromatic portion of a Kuwait gas oil boiling in the range from 218 to 345C are reported. Twenty-eight nonhydrocarbon aromatic components were isolated and identified from their separated fractions. The majority are C{sub 1}-C{sub 5} benzo- and dibenzothiophenes. The compounds were isolated principally by using preparative scale high performance liquid chromatography, and identified by nuclear magnetic resonance and gas chromatography supplemented by mass spectrometry.

  12. Photoactivation and toxicity of mixtures of polycyclic aromatic hydrocarbon compounds in marine sediment

    SciTech Connect

    Swartz, R.C.; Ferraro, S.P.; Lamberson, J.O.; Cole, F.A.; Ozretich, R.J.; Boese, B.L.; Schults, D.W.; Behrenfeld, M.; Ankley, G.T.

    1997-10-01

    The direct toxicity and photoinduced toxicity of sediment-associated acenaphthene, phenanthrene, fluoranthene, and pyrene were determined for the marine amphipod Rhepoxynius abronius. The four polycyclic aromatic hydrocarbons (PAHs) were spiked into sediment in a concentration series of either single compounds or as approximately equitoxic mixtures of all four compounds. Standard 10-d sediment toxicity tests were conducted under fluorescent lighting. After 10 d, survivors were exposed for 1 h to ultraviolet (UV) radiation in the absence of sediment and then tested for their ability to bury in uncontaminated sediment. The 10-d median lethal concentrations (LC50s) were 2.31 mg acenaphthene/g organic carbon (OC), 2.22 mg phenanthrene/g OC, 3.31 mg fluoranthene/g OC, and 2.81 mg pyrene/g OC. These LC50s were used to calculate the sum of toxic units ({Sigma}TU) of the four PAHs in the approximately equitoxic mixtures. The {Sigma}TU LC50 was then calculated for the mixture treatments. If the toxicologic interaction of a mixture of contaminants is additive, {Sigma}TU LC50 = 1.0. The observed LC50 (1.55 {Sigma}TU) was slightly, but significantly, greater than unity, indicating that the interaction of PAHs in the mixture was less than additive. Exposure to UV radiation enhanced the toxic effects of fluoranthene and pyrene, but did not affect the toxicity of acenaphthene and phenanthrene. Effects of UV radiation on the toxicity of the mixture of four PAHs could be explained by the photoactivation of fluoranthene and pyrene alone. These results are consistent with predictions based on photophysical properties of PAH compounds.

  13. Environmental diagnostic analysis of ground water bacteria and their involvement in utilization of aromatic compounds

    SciTech Connect

    Wear, J.E. Jr.

    1993-05-01

    The objective of this study was to examine the hypothesis that select functional groups of bacteria from pristine sites have an innate ability to degrade synthetic aromatics that often contaminate groundwater environments,due to exposure to naturally occurring recalcitrant aromatics in their environment. This study demonstrates that subsurface microbial communities are capable of utilizing lignin and humic acid breakdown products. Utilizers of these compounds were found to be present in most all the wells tested. Even the deepest aquifer tested had utilizers present for all six of the aromatics tested. Highest counts for the aromatics tested were observed with the naturally occurring breakdown products of either lignin or humic acid. Carboxylic acids were found to be an important sole carbon source for groundwater bacteria possibly explained by the fact that they are produced by the oxidative cleavage of aromatic ring structures. The carbohydrate sole carbon sources that demonstrated the greatest densities were ones commonly associated with humics. This study indicates that utilization of naturally occurring aromatic compounds in the subsurface is an important nutritional source for groundwater bacteria. In addition, it suggests that adaptation to naturally occurring recalcitrant substrates is the origin of degradative pathways for xenobiotic compounds with analogous structure. This work has important implications for in situ bioremediation as a method of environmental cleanup.

  14. Synthesis and phtoluminescence study of Microporous Metal Organic Frameworks (MMOFs) for sensing and detection of nitroexplosives and aromatic compounds

    NASA Astrophysics Data System (ADS)

    Pramanik, Sanhita

    Due to the increased terrorist activity worldwide and the use of modern bombs in those attacks, the development of a new method capable of rapidly and cost-efficiently detecting trace vapor of explosives is highly desirable. Chemical explosives composed of a diverse group of compounds, including nitroaromatics, nitramines, nitrate esters as well as some inorganic/organic nitrates and peroxides. Current methodologies include use of well trained dogs and sophisticated instrumentation such as gas chromatography coupled with a mass spectrometer, nuclear quadruple resonance, ionization mass spectrometry (IMS). These methods are highly sensitive and selective, but often expensive, not always easily accessible, and require intense training for operation. As a complementary method, chemical sensors can provide new ways to the rapid detection of ultra trace explosives, and can be easily incorporated into inexpensive and portable microelectronic devices. Fluorescence based sensors utilizing conjugated polymers have attracted enormous attention in the recent years for their excellent performance. In this thesis, a systematic study was performed in a series of luminescent MMOFs and their behavior upon exposure to the vapor of different analytes. For example, [Zn2(oba)2(bpy)]·DMA, one of the MMOFs made of paddle-wheel SBU, selectively responds to nitroaromatics (with electron-withdrawing groups) and other aromatic compounds, like benzene, toluene (with electron-donating groups) via fluorescent quenching and enhancement respectively. The study also shows that nitro-containing non-aromatic analytes (nitroaliphatics) make negligible effect on the fluorescence of [Zn2(oba)2(bpy)]·DMA . The results demonstrate the exceptional ability of this particular MMOF to selectively detect explosives of different types (e.g. aromatic DNT vs. non-aromatic or aliphatic DMNB). Another series of highly luminescent MMOFs made of the same metal center (Zn) and similar ligands (bpdc, bpy, 2,2'dmbpy

  15. Synthesis, spectroscopic characteristic of novel fluorescent dyes of pyrazoline compounds

    NASA Astrophysics Data System (ADS)

    Wang, Hai-Ying; Zhang, Xiao-Xiao; Shi, Jing-Jing; Chen, Gang; Xu, Xiao-Ping; Ji, Shun-Jun

    Four novel fluorescence dyes of the pyrazoline were synthesized and fully characterized by means of 1H, 13C NMR, and HRMS. The optical, electrochemical properties were also investigated. Solvent effect on the fluorescence characteristics of the four compounds indicates that the emission wavelength was red-shifted with the increase of solvent polarity. As we expected, the results indicated that these compounds exhibited high quantum yields. Quantum chemical calculations were used to obtain optimized ground-state geometry, spatial distributions of the HOMO, LUMO levels of the compounds.

  16. Demonstration of the interactions between aromatic compound-loaded lipid nanocapsules and Acinetobacter baumannii bacterial membrane.

    PubMed

    Montagu, A; Joly-Guillou, M-L; Guillet, C; Bejaud, J; Rossines, E; Saulnier, P

    2016-06-15

    Acinetobacter baumannii is an important nosocomial pathogen that is resistant to many commonly-used antibiotics. One strategy for treatment is the use of aromatic compounds (carvacrol, cinnamaldehyde) against A. baumannii. The aim of this study was to determine the interactions between bacteria and lipid nanocapsules (LNCs) over time based on the fluorescence of 3,3'-Dioctadecyloxacarbocyanine Perchlorate-LNCs (DiO-LNCs) and the properties of trypan blue to analyse the physicochemical mechanisms occurring at the level of the biological membrane. The results demonstrated the capacity of carvacrol-loaded LNCs to interact with and penetrate the bacterial membrane in comparison with cinnamaldehyde-loaded LNCs and unloaded LNCs. Modifications of carvacrol after substitution of hydroxyl functional groups by fatty acids demonstrated the crucial role of hydroxyl functions in antibacterial activity. Finally, after contact with the efflux pump inhibitor, carbonylcyanide-3-chlorophenyl hydrazine (CCCP), the results indicated the total synergistic antibacterial effect with Car-LNCs, showing that CCCP is associated with the action mechanism of carvacrol, especially at the level of the efflux pump mechanism. PMID:27039148

  17. Process for reducing aromatic compounds in ethylenediamine with calcium

    DOEpatents

    Benkeser, Robert A.; Laugal, James A.; Rappa, Angela

    1985-01-01

    Olefins are produced by containing an organic compound having at least one benzene ring with ethylenediamine and calcium metal, the calcium metal being used in large excess or alternatively in conjunction with an inert abrasive particulate substance. Substantially all of the organic compounds are converted to corresponding cyclic olefins, largely mono-olefins.

  18. Process for reducing aromatic compounds in ethylenediamine with calcium

    DOEpatents

    Benkeser, R.A.; Laugal, J.A.; Rappa, A.

    1985-08-06

    Olefins are produced by containing an organic compound having at least one benzene ring with ethylenediamine and calcium metal, the calcium metal being used in large excess or alternatively in conjunction with an inert abrasive particulate substance. Substantially all of the organic compounds are converted to corresponding cyclic olefins, largely mono-olefins.

  19. Postfunctionalization of BN-embedded polycyclic aromatic compounds for fine-tuning of their molecular properties.

    PubMed

    Wang, Xiao-Ye; Yang, Dong-Chu; Zhuang, Fang-Dong; Liu, Jia-Jie; Wang, Jie-Yu; Pei, Jian

    2015-06-01

    New BN-embedded, thiophene-fused, polycyclic aromatic compounds with planar geometry were designed and synthesized. The molecules showed excellent stability and chemical robustness. Postfunctionalization on this skeleton was demonstrated with a series of electrophilic bromination, palladium-catalyzed cross-coupling, and Knoevenagel condensation reactions. The π skeleton remained intact during these late-stage transformations. The optical and electronic properties have been well tuned through incorporation of electron-rich and -deficient groups on the backbone. This work shows the great advantage of the postfunctionalization strategy on BN-containing polycyclic aromatic compounds for fast diversification and materials screening. PMID:25955825

  20. Determination of aromatic compounds in water by solid phase microextraction and ultraviolet absorption spectroscopy. 2. Application to fuel aromatics

    SciTech Connect

    Wittkamp, B.L.; Tilotta, D.C.; Hawthorne, S.B.

    1997-03-15

    Solid phase microextraction is coupled with ultraviolet absorption spectroscopy to determine fuel aromatic hydrocarbons from unleaded gasoline, jet fuel (JP4), and no. 1 diesel fuel in water. A rectangular `chip` of poly(dimethylsiloxane) (OV-1) was used as the sorbent medium to selectively partition the various fuels from real water matrices without interferences from naturally occurring organics (e.g., humic and fulvic acids). Equilibration times are under 45 min for the majority of aromatic compounds and range from 150 to 300 min for the three fuels. However, it is shown that the fuels can be quantitated at significantly shorter extraction times (45 min), resulting in only a loss of nearly 2x in the detection limits. Detection limits for unleaded gasoline, JP4, and no. 1 diesel fuel (obtained at their 100% equilibration times) are 4.9, 17, and 9.0 ppb, respectively. In addition, recovery data for the aromatic components from unleaded gasoline, JP4, and no. 1 diesel fuel from two real water matrices are in the range of 87-106%, with RSDs in the range of 5.0-10%. 4 refs., 2 figs., 6 tabs.

  1. Light emission from compound eye with conformal fluorescent coating

    NASA Astrophysics Data System (ADS)

    Martín-Palma, Raúl J.; Miller, Amy E.; Pulsifer, Drew P.; Lakhtakia, Akhlesh

    2015-03-01

    Compound eyes of insects are attractive biological systems for engineered biomimicry as artificial sources of light, given their characteristic wide angular field of view. A blowfly eye was coated with a thin conformal fluorescent film, with the aim of achieving wide field-of-view emission. Experimental results showed that the coated eye emitted visible light and that the intensity showed a weaker angular dependence than a fluorescent thin film deposited on a flat surface.

  2. Aromatic fluorine compounds. VIII. Plant growth regulators and intermediates

    USGS Publications Warehouse

    Finger, G.C.; Gortatowski, M.J.; Shiley, R.H.; White, R.H.

    1959-01-01

    The preparation and properties of 41 fluorophenoxyacetic acids, 4 fluorophenoxypropionic acids, 2 fluorobenzoic acids, several indole derivatives, and a number of miscellaneous compounds are described. Data are given for many intermediates such as new fluorinated phenols, anisoles, anilines and nitrobenzenes. Most of the subject compounds are related to a number of well-known herbicides or plant growth regulators such as 2,4-D, 2,4,5-T and others.

  3. Infrared Spectroscopy of Matrix-Isolated Polycyclic Aromatic Compounds and their Ions. 6; Polycyclic Aromatic Nitrogen Heterocycles

    NASA Technical Reports Server (NTRS)

    Mattioda, A. L.; Hudgins, Douglas M.; Bauschlicher, C. W., Jr.; Rosi, M.; Allamandola, L. J.; DeVincenzi, D. (Technical Monitor)

    2002-01-01

    The matrix-isolation technique has been employed to measure the mid-infrared spectra of several polycyclic aromatic nitrogen heterocycles in both neutral and cationic forms. The species studied include: 7,8 benzoquinoline (C13H9N); 2-azapyrene (C15H9N); 1- and 2-azabenz(a)anthracene (C17H11N); and 1-, 2-, and 4-azachrysene (also C17H11N). The experimentally measured band frequencies and intensities for each molecule are tabulated and compared with their theoretically calculated values computed using density functional theory at the B3LYP/4-31G level. The overall agreement between experiment and theory is quite good, in keeping with previous investigations involving the parent aromatic hydrocarbons. Several interesting spectroscopic trends are found to accompany nitrogen substitution into the aromatic framework of these compounds. First, for the neutral species, the nitrogen atom produces a significant increase in the total integrated infrared intensity across the 1600 - 1100/cm region and plays an essential role in the molecular vibration that underlies an uncharacteristically intense, discrete feature that is observed near 1400/cm in the spectra of 7,8 benzoquinoline, 1-azabenz(a)anthracene, and 4-azachrysene. The origin of this enhanced infrared activity and the nature of the new 1400/cm vibrational mode are explored. Finally, in contrast to the parent hydrocarbon species, these aromatic nitrogen heterocycles possess a significant permanent dipole moment. Consequently, these dipole moments and the rotational constants are reported for these species in their neutral and ionized forms.

  4. Azoarcus sp. CIB, an Anaerobic Biodegrader of Aromatic Compounds Shows an Endophytic Lifestyle

    PubMed Central

    Fernández, Helga; Prandoni, Nicolás; Fernández-Pascual, Mercedes; Fajardo, Susana; Morcillo, César; Díaz, Eduardo; Carmona, Manuel

    2014-01-01

    Background Endophytic bacteria that have plant growth promoting traits are of great interest in green biotechnology. The previous thought that the Azoarcus genus comprises bacteria that fit into one of two major eco-physiological groups, either free-living anaerobic biodegraders of aromatic compounds or obligate endophytes unable to degrade aromatics under anaerobic conditions, is revisited here. Methodology/Principal Findings Light, confocal and electron microscopy reveal that Azoarcus sp. CIB, a facultative anaerobe β-proteobacterium able to degrade aromatic hydrocarbons under anoxic conditions, is also able to colonize the intercellular spaces of the rice roots. In addition, the strain CIB displays plant growth promoting traits such nitrogen fixation, uptake of insoluble phosphorus and production of indoleacetic acid. Therefore, this work demonstrates by the first time that a free-living bacterium able to degrade aromatic compounds under aerobic and anoxic conditions can share also an endophytic lifestyle. The phylogenetic analyses based on the 16S rDNA and nifH genes confirmed that obligate endophytes of the Azoarcus genus and facultative endophytes, such as Azoarcus sp. CIB, locate into different evolutionary branches. Conclusions/Significance This is the first report of a bacterium, Azoarcus sp. CIB, able to degrade anaerobically a significant number of aromatic compounds, some of them of great environmental concern, and to colonize the rice as a facultative endophyte. Thus, Azoarcus sp. CIB becomes a suitable candidate for a more sustainable agricultural practice and phytoremediation technology. PMID:25340341

  5. Fluorescent Analysis of Photosynthetic Microbes and Polycyclic Aromatic Hydrocarbons Linked to Optical Remote Sensing

    NASA Astrophysics Data System (ADS)

    Zhang, D.; Muller, J.-P.; Lavender, S.; Walton, D.; Dartnell, L. R.

    2012-07-01

    Fluorescence analysis, being a non-invasive technique, has become one of the most powerful and widely used techniques for microbiologists and chemists to study various types of sample from photosynthetic microbes to hydrocarbons. The work reported here focuses on experimental results of fluorescent features of photosynthetic microbial species (cyanobacteria) and also five different crude oil samples. The cyanobacteria samples were collected from the Baltic Sea at the end of July 2011 and were associated with cyanobacterial bloom events, and the crude oil samples were from various oil spill events. The aim of the study was to find fluorescent biosignatures of cyanobacteria (initially a species specific to the Baltic Sea) and the fingerprints of crude oil; oil spills can be difficult to differentiate from biogenic films when using Synthetic Aperture Radar (SAR) or sunglint contaminated optical imagery. All samples were measured using a Perkin Elmer LS55 Luminescence spectrometer over a broad range of excitation and emission wavelength from ultraviolet (UV) to near infrared (NIR). The results are presented in Excitation Emission Matrices (EEMs) that exhibit the fluorescent features of each sample. In the EEM of the seawater sample containing cyanobacteria, there is an intense emission peak from tryptophan with fluorescent excitation and emission peaks at 285 and 345 nm respectively. In addition, fluorescent signatures of phycocyanin and chlorophyll-a are present with excitation and emission centre wavelengths at 555 nm, 645 nm and 390 nm, 685 nm, respectively. Additionally, the fluorescence signatures of Polycyclic Aromatic Hydrocarbons (PAHs) are present in the EEMs of crude oil samples with excitation and emission peaks at 285 nm and 425 nm. This study underpins further research on how to distinguish cyanobacteria species by their fluorescence signatures and the potential role that PAHs play in detection of cyanobacteria fluorescence features.

  6. Formation of Polycyclic Aromatic Hydrocarbons and Nitrogen Containing Polycyclic Aromatic Compounds in Titan's Atmosphere, the Interstellar Medium and Combustion

    NASA Astrophysics Data System (ADS)

    Landera, Alexander

    2013-12-01

    Several different mechanisms leading to the formation of (substituted) naphthalene and azanaphthalenes were examined using theoretical quantum chemical calculations. As a result, a series of novel synthetic routes to Polycyclic Aromatic Hydrocarbons (PAHs) and Nitrogen Containing Polycyclic Aromatic Compounds (N-PACs) have been proposed. On Earth, these aromatic compounds originate from incomplete combustion and are released into our environment, where they are known to be major pollutants, often with carcinogenic properties. In the atmosphere of a Saturn's moon Titan, these PAH and N-PACs are believed to play a critical role in organic haze formation, as well as acting as chemical precursors to biologically relevant molecules. The theoretical calculations were performed by employing the ab initio G3(MP2,CC)/B3LYP/6-311G** method to effectively probe the Potential Energy Surfaces (PES) relevant to the PAH and N-PAC formation. Following the construction of the PES, Rice-Ramsperger-Kassel-Markus (RRKM) theory was used to evaluate all unimolecular rate constants as a function of collision energy under single-collision conditions. Branching ratios were then evaluated by solving phenomenological rate expressions for the various product concentrations. The most viable pathways to PAH and N-PAC formation were found to be those where the initial attack by the ethynyl (C2H) or cyano (CN) radical toward a unsaturated hydrocarbon molecule led to the formation of an intermediate which could not effectively lose a hydrogen atom. It is not until ring cyclization has occurred, that hydrogen elimination leads to a closed shell product. By quenching the possibility of the initial hydrogen atom elimination, one of the most competitive processes preventing the PAH or N-PAC formation was avoided, and the PAH or N-PAC formation was allowed to proceed. It is concluded that these considerations should be taken into account when attempting to explore any other potential routes towards

  7. Complete genome sequence of an aromatic compound degrader Arthrobacter sp. YC-RL1.

    PubMed

    Ren, Lei; Jia, Yang; Ruth, Nahurira; Zhao, Baisuo; Yan, Yanchun

    2016-02-10

    Arthrobacter sp. YC-RL1, isolated from a petroleum-contaminated soil, is capable of degrading and utilizing a wide range of aromatic compounds for growth. Here we report the complete genome sequence of strain YC-RL1, which may facilitate the investigation of environmental bioremediation and provide new gene resources for biotechnology and gene engineering. PMID:26699229

  8. CHLORINE 'DISINFECTION' CHEMISTRY OF AROMATIC COMPOUNDS. POLYNUCLEAR AROMATIC HYDROCARBONS: RATES, PRODUCTS, AND MECHANISMS

    EPA Science Inventory

    The use of chlorine for water renovation and disinfection has been questioned because of the reaction of active chlorine species with organic compounds present in water to form products that may be biologically harmful. Among the organic species known to be present during chlorin...

  9. Photoinduced proton transfer and isomerization in a hydrogen-bonded aromatic azo compound: a CASPT2//CASSCF study.

    PubMed

    Cui, Ganglong; Guan, Pei-Jie; Fang, Wei-Hai

    2014-07-01

    Intramolecularly hydrogen-bonded aromatic azo compound 1-cyclopropyldiazo-2-naphthol (CPDNO) exhibits complicated excited-state behaviors, e.g., wavelength-dependent photoinduced proton transfer and photoproducts. Its photochemistry differs from that of common aromatic azo compounds in which cis-trans photoisomerization is dominant. To rationalize the intriguing photochemistry of CPDNO at the atomic level, we have in this work employed the complete active space self-consistent field (CASSCF) and its second-order perturbation (CASPT2) methods to explore the S0, S1, and S2 potential-energy profiles relevant to enol-keto proton transfer and isomerization reactions. It is found that the proton transfer along the bright diabatic (1)ππ* potential-energy profile is almost barrierless, quickly forming the fluorescent (1)ππ* keto minimum. In this process, the dark (1)nπ* state is populated via a (1)ππ*/(1)nπ* crossing point, but the proton transfer on this dark state is suppressed heavily as a result of a large barrier. In addition, two deactivation paths that decay the S1 enol and keto minima to the S0 state, respectively, were uncovered. For the former, it is exoenergetic and thereby thermodynamically favorable; for the latter, it is a little endothermic (ca. 5 kcal/mol). Both are energetically allowable concerning the available total energy. Finally, on the basis of the present results, the experimentally observed wavelength-dependent photoproducts were explained very well. PMID:24940848

  10. Bioactive aromatic compounds from leaves and stems of Vanilla fragrans.

    PubMed

    Sun, R; Sacalis, J N; Chin, C K; Still, C C

    2001-11-01

    Alcoholic extracts of leaves and stems of Vanilla fragrans were fractionated with ethyl acetate and aqueous butanol. All three fractions of ethyl acetate, butanol, and water were screened for toxic bioactivity against mosquito larvae. The results of these experiments showed that the fractions from the ethyl acetate and butanol phases were both active in the bioassay. Bioactivity of the ethyl acetate fraction was found to be much greater than that from the butanol fraction in mosquito larvae toxicity. The water phase appeared to contain no substances that impaired mosquito larval growth. Repeated column chromatography of the ethyl acetate fraction on silica gel led to the isolation of 4-ethoxymethylphenol (1), 4-butoxymethylphenol (2), vanillin (3), 4-hydroxy-2-methoxycinnamaldehyde (4), and 3,4-dihydroxyphenylacetic acid (5). Compounds 4 and 5 were isolated from Vanilla species for the first time and 2 has not been reported to have been found in a natural form. 4-Ethoxymethylphenol (1) was the predominant compound, but 4-butoxymethylphenol (2) showed the strongest toxicity to mosquito larvae. The structures of the compounds were determined on the basis of their mass spectra and (1)H or (13)C NMR data. PMID:11714297

  11. PHENAZINE COMPOUNDS IN FLUORESCENT PSEUDOMONAS SPP.: BIOSYNTHESIS AN REGULATION

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The phenazines include upward of 50 pigmented, heterocyclic nitrogen-containing secondary metabolites synthesized by some strains of fluorescent Pseudomonas spp. and a few other bacterial genera. The antibiotic properties of these compounds have been known for over 150 years, but advances within the...

  12. Detection of Medium-Sized Polycyclic Aromatic Hydrocarbons via Fluorescence Energy Transfer

    PubMed Central

    Serio, Nicole; Prignano, Lindsey; Peters, Sean; Levine, Mindy

    2015-01-01

    Reported herein is the use of proximity-induced non-covalent energy transfer for the detection of medium-sized polycyclic aromatic hydrocarbons (PAHs). This energy transfer occurs within the cavity of γ-cyclodextrin in various aqueous environments, including human plasma and coconut water. Highly efficient energy transfer was observed, and the efficiency of the energy transfer is independent of the concentration of γ-cyclodextrin used, demonstrating the importance of hydrophobic binding in facilitating such energy transfer. Low limits of detection were also observed for many of the PAHs investigated, which is promising for the development of fluorescence-based detection schemes. PMID:25821390

  13. Fluorescent aromatic hydrocarbons in bile as a biomarker of exposure of brown bullheads (Ameiurus nebulosus) to contaminated sediments

    SciTech Connect

    Leadly, T.A.; Haffner, G.D.; Arcand-Hoy, L.D.; Metcalfe, C.D.

    1999-04-01

    Analysis of fluorescent aromatic compounds (FACs) in the bile of fish has been widely used as a biomarker of exposure to polynuclear aromatic hydrocarbon (PAH) contamination. However, bile FAC data for feral fish populations are typically highly variable, and in a few cases, elevation of FACs has not been observed in fish from contaminated areas. In this study, the bile FACs and hepatic ethoxyresorufin-O-deethylase activity in brown bullheads (Ameiurus nebulosus) exposed in the laboratory to contaminated sediments from Hamilton Harbour, Ontario, Canada, increased by 173-fold within 72 h of initial exposure and rapidly declined thereafter. In bullheads caged in the contaminated Trenton Channel area of the Detroit River, bile FACs also increased rapidly within 4 d of initial exposure to mean levels >3,000 ng of benzo[a]pyrene equivalents per milliliter of bile. Surprisingly, there was no difference in the mean-levels of bile FACs in fish caged above the sediment versus fish caged in direct contact with the sediment, indicating that water may be the major vector for uptake of PAHs. The lower bile FACs in bullheads caged in other regions of the Detroit River were consistent with the lower concentrations of PAHs in the sediments from these areas. These data indicate that bile FAC levels are a biomarker of recent exposure to aromatic hydrocarbons in sediments. However, FAC data were highly variable even in these studies, in which fish were relatively homogenous in size, feeding status, and exposure history. Therefore, Even higher variability in bile FAC data are expected in biomarker studies as a result of differences in reproductive status, size, diet, and mobility of the fish.

  14. Biotransformation of N-substituted aromatic compounds in mammalian spermatozoa. Nonoxidative formation of N-hydroxy-N-arylacetamides from nitroso aromatic compounds.

    PubMed

    Yoshioka, T; Suzuki, T; Uematsu, T

    1989-07-25

    The metabolism of N-substituted aromatic compounds, i.e. aniline, acetanilide, N-hydroxyacetanilide, nitrosobenzene, and nitrobenzene in mammalian spermatozoa was investigated. In boar spermatozoa fortified with glucose, no acetylation, deacetylation, and monooxygenation of these compounds were found. Nitrobenzene was reduced slowly, but nitrosobenzene was a good substrate for this reductive activity. In the latter reaction, the products were N-hydroxyacetanilide, azoxybenzene, and an organic phase-nonextractable metabolite(s). Pyruvate was found to be involved in the formation of N-hydroxyacetanilide from nitrosobenzene, and the reaction occurred through a ping-pong mechanism. This enzymatic activity, located in the mid-piece fraction of spermatozoa, was enhanced by thiamine pyrophosphate and Mg2+ and inhibited by thiamine thiazolone pyrophosphate. N-Hydroxyacetanilide formed from [3(-13)C]pyruvate showed complete retention of the isotope at the methyl carbon of the molecule. 2-Nitrosofluorene and 4-nitrosobiphenyl were also transformed into the corresponding N-hydroxy-N-arylacetamides. N-Hydroxyacetanilide was also formed in rat and human spermatozoa. These facts suggest that the formation of N-hydroxy-N-arylacetamides from the nitroso aromatic compounds and pyruvate is mediated by a pyruvate dehydrogenase complex located in the mitochondria of spermatozoa. The formation of both azoxybenzene and the organic phase-nonextractable metabolite(s) was found to be a pyruvate-independent nonenzymatic reaction. PMID:2745452

  15. Bacterial Community Dynamics during Start-Up of a Trickle-Bed Bioreactor Degrading Aromatic Compounds

    PubMed Central

    Stoffels, Marion; Amann, Rudolf; Ludwig, Wolfgang; Hekmat, Dariusch; Schleifer, Karl-Heinz

    1998-01-01

    This study was performed with a laboratory-scale fixed-bed bioreactor degrading a mixture of aromatic compounds (Solvesso100). The starter culture for the bioreactor was prepared in a fermentor with a wastewater sample of a car painting facility as the inoculum and Solvesso100 as the sole carbon source. The bacterial community dynamics in the fermentor and the bioreactor were examined by a conventional isolation procedure and in situ hybridization with fluorescently labeled rRNA-targeted oligonucleotides. Two significant shifts in the bacterial community structure could be demonstrated. The original inoculum from the wastewater of the car factory was rich in proteobacteria of the alpha and beta subclasses, while the final fermentor enrichment was dominated by bacteria closely related to Pseudomonas putida or Pseudomonas mendocina, which both belong to the gamma subclass of the class Proteobacteria. A second significant shift was observed when the fermentor culture was transferred as inoculum to the trickle-bed bioreactor. The community structure in the bioreactor gradually returned to a higher complexity, with the dominance of beta and alpha subclass proteobacteria, whereas the gamma subclass proteobacteria sharply declined. Obviously, the preceded pollutant adaptant did not lead to a significant enrichment of bacteria that finally dominated in the trickle-bed bioreactor. In the course of experiments, three new 16S as well as 23S rRNA-targeted probes for beta subclass proteobacteria were designed, probe SUBU1237 for the genera Burkholderia and Sutterella, probe ALBO34a for the genera Alcaligenes and Bordetella, and probe Bcv13b for Burkholderia cepacia and Burkholderia vietnamiensis. Bacteria hybridizing with the probe Bcv13b represented the main Solvesso100-degrading population in the reactor. PMID:9501433

  16. Studies on the dermal and systemic bioavailability of polycyclic aromatic compounds in high viscosity oil products.

    PubMed

    Potter, D; Booth, E D; Brandt, H C; Loose, R W; Priston, R A; Wright, A S; Watson, W P

    1999-01-01

    The assessment of skin penetration by viscous oil products is an important element in the risk assessment of these materials where skin contact is likely. Systemic bioavailability (body uptake) is viewed as a good indicator of skin penetration following cutaneous exposures. The results of this study provide quantitative information on the influence of viscosity on the bioavailability of a specific polycyclic aromatic compound (benzo(a)pyrene) in base oils, residual aromatic extracts and bitumens following skin exposures to mice. The materials studied were a base mineral oil (viscosity 32 cSt at 35 degrees C), a 1:1 blend of the mineral base oil and a residual aromatic extract (198 cSt), several residual aromatic extracts (ca. 5000 cSt, 35 degrees C) and a range of bitumens (0.65-69 x 10(6) cSt, 35 degrees C). These were each spiked with 0.1% radiolabelled benzo(a)pyrene, as a representative carcinogenic polycyclic aromatic compound, then used for cutaneous exposures to mice. The results indicate that as viscosity increased in the range ca. 30 to 5000 cSt (base oil to residual aromatic extract) the uptake of the radiolabelled benzo(a)pyrene into blood was reduced by ca. fivefold. Further increases in viscosity from ca. 5000 to 69 x 10(6) cSt (i.e. residual aromatic extract to bitumen) resulted in a further but smaller (ca. twofold) reduction in uptake. The relationship between the amounts of free benzo(a)pyrene measured in blood and viscosity showed the same trend. This trend was also mirrored by the degree of binding of benzo(a)pyrene metabolites to DNA in skin. The findings in mouse skin in vivo indicate that viscosity can significantly affect skin penetration and systemic bioavailability of polycyclic aromatic compound components of oil products. Results obtained with viable human skin in vitro also showed that the bioavailability of benzo(a)pyrene was reduced by the viscosity of the oil product matrix. It is thus necessary to take account of physical properties

  17. Destruction of polychlorinated aromatic compounds by spinel-type complex oxides.

    PubMed

    Fan, Yun; Lu, Xianbo; Ni, Yuwen; Zhang, Haijun; Zhao, Liang; Chen, Jiping; Sun, Chenglin

    2010-04-15

    Destruction of polychlorinated aromatic compounds was carried out over spinel-type catalysts XY2O4 (where X = Mg, Ca, Cu, Ni, Zn, and Y = Al, Fe). The catalysts were characterized by XRD, nitrogen adsorption-desorption isotherms and FTIR. The performance of these catalysts toward the decomposition of hexachlorobenzene (HCB) and octachlorodibenzo-p-dioxin (OCDD) was evaluated in a closed system. The spinel-type catalyst with mesoporous structure demonstrated high catalytic activity for the hydrodechlorination of polychlorinated aromatic compounds. Among them, the copper-aluminum spinel (CuAl2O4), specifically calcined at 600 degrees C, exhibited the best activity. More than 85% dechlorination efficiency of HCB and 99% decomposition of polychlorinated dibenzodioxin (PCDD) were achieved at 250 degrees C for 30 min over the above catalyst which was more effective than the corresponding metallic copper and copper oxide catalysts during the thermal degradation of polychlorinated aromatic compounds. The correlation of catalytic performance to structural characteristics is discussed based on the detailed characterization. The simple preparation procedure and reasonable cost of the spinel-type catalysts present a good potential for the thermal treatment of polychlorinated aromatic pollutants at lower temperatures. PMID:20334415

  18. Actions of a versatile fluorene-degrading bacterial isolate on polycyclic aromatic compounds.

    PubMed Central

    Grifoll, M; Selifonov, S A; Gatlin, C V; Chapman, P J

    1995-01-01

    Pseudomonas cepacia F297 grew with fluorene as a sole source of carbon and energy; its growth yield corresponded to an assimilation of about 40% of fluorene carbon. The accumulation of a ring meta-cleavage product during growth and the identification of 1-indanone in growth media and washed-cell suspensions suggest that strain F297 metabolizes fluorene by mechanisms analogous to those of naphthalene degradation. In addition to fluorene, strain F297 utilized for growth a wide variety of polycyclic aromatic compounds (PACs), including naphthalene, 2,3-dimethylnaphthalene, phenanthrene, anthracene, and dibenzothiophene. Fluorene-induced cells of the strain also transformed 2,6-dimethylnaphthalene, biphenyl, dibenzofuran, acenaphthene, and acenaphthylene. The identification of products formed from those substrates (by gas chromatography-mass spectrometry) in washed-cell suspensions indicates that P. cepacia F297 carries out the following reactions: (i) aromatic ring oxidation and cleavage, apparently using the pyruvate released for growth, (ii) methyl group oxidations, (iii) methylenic oxidations, and (iv) S oxidations of aromatic sulfur heterocycles. Strain F297 grew with a creosote-PAC mixture, producing an almost complete removal of all aromatic compounds containing 2 to 3 rings in 14 days, as demonstrated by gas chromatography analysis of the remaining PACs recovered from cultures. The identification of key chemicals confirmed that not only are certain compounds depleted but also the anticipated reaction products are found. PMID:7487007

  19. Biosynthesis of polybrominated aromatic organic compounds by marine bacteria

    PubMed Central

    Agarwal, Vinayak; El Gamal, Abrahim A.; Yamanaka, Kazuya; Poth, Dennis; Kersten, Roland D.; Schorn, Michelle; Allen, Eric E.; Moore, Bradley S.

    2014-01-01

    Polybrominated diphenyl ethers (PBDEs) and polybrominated bipyrroles are natural products that bioaccumulate in the marine food chain. PBDEs have attracted widespread attention due to their persistence in the environment and potential toxicity to humans. However, the natural origins of PBDE biosynthesis are not known. Here we report marine bacteria as producers of PBDEs and establish a genetic and molecular foundation for their production that unifies paradigms for the elaboration of bromophenols and bromopyrroles abundant in marine biota. We provide biochemical evidence of marine brominase enzymes revealing decarboxylative-halogenation enzymology previously unknown among halogenating enzymes. Biosynthetic motifs discovered in our study were used to mine sequence databases to discover unrealized marine bacterial producers of organobromine compounds. PMID:24974229

  20. Investigation of fixed wavelength fluorescence results for biliary metabolites of polycyclic aromatic hydrocarbons formed in Atlantic cod (Gadus morhua).

    PubMed

    Pampanin, Daniela M; Kemppainen, Eeva K; Skogland, Karianne; Jørgensen, Kåre B; Sydnes, Magne O

    2016-02-01

    Fixed wavelength fluorescence (FF) and synchronous fluorescence scanning (SFS) of fish bile are commonly used methods to analyze for exposure to polycyclic aromatic hydrocarbons (PAHs) from petrogenic and pyrogenic sources. A range of conjugated oxidation products from petrogenic PAHs are normally accumulated in the bile. Therefore their detection is important. In the present study, phenanthrene and naphthalene metabolites, formed in vivo in Atlantic cod (Gadus morhua), were used to study the response of these compounds in both FF and SFS analyses. The selected synthetic metabolites were (-)-(1R,2R)-1,2-dihydrophenanthrene-1,2-diol and (-)-(1R,2R)-1,2-dihydronaphthalene-1,2-diol. The study findings showed that the recommended excitation and emission wavelengths for FF analysis do not comprise the maximum emission wavelengths for these metabolites, providing an incorrect estimation of the PAH exposure. A method developed in our laboratory for the synthesis of (-)-(1R,2R)-1,2-dihydrophenanthrene-1,2-diol is also described. PMID:26492423

  1. POLYCYCLIC AROMATIC HYDROCARBONS FROM U.S. AND ANTARCTIC SITES ANALYZED WITH SYNCHRONOUS FLUORESCENCE SPECTROMETRY

    EPA Science Inventory

    Synchronous ultraviolet-visible (UV-vis) fluorescence spectrometry is currently being evaluated as a field screening technology by the U.S. Environmental Protection Agency's (EPA) Environmental Monitoring Systems Laboratory in Las Vegas, Nevada. his method can provide compound- o...

  2. Analysis of preference for carbon source utilization among three strains of aromatic compounds degrading Pseudomonas.

    PubMed

    Karishma, M; Trivedi, Vikas D; Choudhary, Alpa; Mhatre, Akanksha; Kambli, Pranita; Desai, Jinal; Phale, Prashant S

    2015-10-01

    Soil isolates Pseudomonas putida CSV86, Pseudomonas aeruginosa PP4 and Pseudomonas sp. C5pp degrade naphthalene, phthalate isomers and carbaryl, respectively. Strain CSV86 displayed a diauxic growth pattern on phenylpropanoid compounds (veratraldehyde, ferulic acid, vanillin or vanillic acid) plus glucose with a distinct second lag-phase. The glucose concentration in the medium remained constant with higher cell respiration rates on aromatics and maximum protocatechuate 3,4-dioxygenase activity in the first log-phase, which gradually decreased in the second log-phase with concomitant depletion of the glucose. In strains PP4 and C5pp, growth profile and metabolic studies suggest that glucose is utilized in the first log-phase with the repression of utilization of aromatics (phthalate or carbaryl). All three strains utilize benzoate via the catechol 'ortho' ring-cleavage pathway. On benzoate plus glucose, strain CSV86 showed preference for benzoate over glucose in contrast to strains PP4 and C5pp. Additionally, organic acids like succinate were preferred over aromatics in strains PP4 and C5pp, whereas strain CSV86 co-metabolizes them. Preferential utilization of aromatics over glucose and co-metabolism of organic acids and aromatics are found to be unique properties of P. putida CSV86 as compared with strains PP4 and C5pp and this property of strain CSV86 can be exploited for effective bioremediation. PMID:26316546

  3. A direct experimental evidence for an aromatic C-H⋯O hydrogen bond by fluorescence-detected infrared spectroscopy

    NASA Astrophysics Data System (ADS)

    Venkatesan, V.; Fujii, A.; Ebata, T.; Mikami, N.

    2004-08-01

    Formation of a weak aromatic C-H⋯O hydrogen bond has been discerned both experimentally and computationally in the 1,2,4,5-tetrafluorobenzene (TFB)-water system. The intermolecular structure of the isolated TFB-water cluster in a supersonic jet was characterized using fluorescence-detected infrared spectroscopy. The formation of a weak hydrogen bond in the cluster was directly evidenced by a low-frequency shift and intensity enhancement of the hydrogen-bonded aromatic C-H stretch in the TFB moiety. This is the first direct observation of an aromatic C-H⋯O hydrogen bond in isolated gas phase clusters.

  4. Lignin Peroxidase Oxidation of Aromatic Compounds in Systems Containing Organic Solvents

    PubMed Central

    Vazquez-Duhalt, Rafael; Westlake, Donald W. S.; Fedorak, Phillip M.

    1994-01-01

    Lignin peroxidase from Phanerochaete chrysosporium was used to study the oxidation of aromatic compounds, including polycyclic aromatic hydrocarbons and heterocyclic compounds, that are models of moieties of asphaltene molecules. The oxidations were done in systems containing water-miscible organic solvents, including methanol, isopropanol, N, N-dimethylformamide, acetonitrile, and tetrahydrofuran. Of the 20 aromatic compounds tested, 9 were oxidized by lignin peroxidase in the presence of hydrogen peroxide. These included anthracene, 1-, 2-, and 9-methylanthracenes, acenaphthene, fluoranthene, pyrene, carbazole, and dibenzothiophene. Of the compounds studied, lignin peroxidase was able to oxidize those with ionization potentials of <8 eV (measured by electron impact). The reaction products contain hydroxyl and keto groups. In one case, carbon-carbon bond cleavage, yielding anthraquinone from 9-methylanthracene, was detected. Kinetic constants and stability characteristics of lignin peroxidase were determined by using pyrene as the substrate in systems containing different amounts of organic solvent. Benzyl alkylation of lignin peroxidase improved its activity in a system containing water-miscible organic solvent but did not increase its resistance to inactivation at high solvent concentrations. PMID:16349176

  5. Lignin peroxidase oxidation of aromatic compounds in systems containing organic solvents.

    PubMed

    Vazquez-Duhalt, R; Westlake, D W; Fedorak, P M

    1994-02-01

    Lignin peroxidase from Phanerochaete chrysosporium was used to study the oxidation of aromatic compounds, including polycyclic aromatic hydrocarbons and heterocyclic compounds, that are models of moieties of asphaltene molecules. The oxidations were done in systems containing water-miscible organic solvents, including methanol, isopropanol, N, N-dimethylformamide, acetonitrile, and tetrahydrofuran. Of the 20 aromatic compounds tested, 9 were oxidized by lignin peroxidase in the presence of hydrogen peroxide. These included anthracene, 1-, 2-, and 9-methylanthracenes, acenaphthene, fluoranthene, pyrene, carbazole, and dibenzothiophene. Of the compounds studied, lignin peroxidase was able to oxidize those with ionization potentials of <8 eV (measured by electron impact). The reaction products contain hydroxyl and keto groups. In one case, carbon-carbon bond cleavage, yielding anthraquinone from 9-methylanthracene, was detected. Kinetic constants and stability characteristics of lignin peroxidase were determined by using pyrene as the substrate in systems containing different amounts of organic solvent. Benzyl alkylation of lignin peroxidase improved its activity in a system containing water-miscible organic solvent but did not increase its resistance to inactivation at high solvent concentrations. PMID:16349176

  6. Microbial treatment of contaminant mixture of chlorinated solvent, aromatic compounds and chromate under anaerobic environments

    SciTech Connect

    Shen, H.; Sewell, G.W.; Pritchard, P.H.

    1996-12-31

    Chlorinated ethylenes and chromium contamination of the subsurface is a common environmental problem due to their wide spread use in industry, and improper disposal practices or accidental releases. Aromatic compounds, among the most industrial contaminants of ground water, are often mixed together with chlorinated solvents and metals including chromate in polluted sites. A cost-effective method is needed for remediation of soil and ground water contaminated with these toxicants. One promising approach may use native bacteria to reductively transform chromate and chlorinated ethylenes. This process reduces the toxic chromate to the less soluble and less toxic trivalent chromium. Although this process leaves the metal in the subsurface, it decreases both the hazard and exposure, and thus the risk to human health associated with chromium. The microorganisms are capable of removing one or more chlorines from the chlorinated compounds under anaerobic environments, and eventually transforming them to ethylene, an environmentally accepted compounds. The use of microorganisms for degradation of aromatic contaminants is also an extensively used method to remediate the contamination. Therefore, one possible approach may link the bacteria catalyzed oxidation of aromatic compounds to the microbial chromate reduction or solvent dechlorination. Microcosm tests will be presented in this study to show the feasibility of the microbial approach for the concurrent detoxification of multiple contaminants.

  7. Pseudomonads biodegradation of aromatic compounds in oil sands process-affected water.

    PubMed

    Zhang, Yanyan; McPhedran, Kerry N; Gamal El-Din, Mohamed

    2015-07-15

    Aromatic naphthenic acids (NAs) have been shown to be more toxic than the classical NAs found in oil sands process-affected water (OSPW). To reduce this toxicity, Pseudomonas fluorescens and Pseudomonas putida were used to determine their ability to biodegrade aromatic compounds including treatments considering the impacts of external carbon and iron addition. Results showed that with added carbon P. fluorescens and P. putida have the capability of biodegrading these aromatics. In the presence of external carbon, gene expression of a functional PAH-ring hydroxylating dioxygenase (PAH-RHDα) was determined through reverse transcription real-time PCR, suggesting active degradation of OSPW aromatic compounds. Although no significant classical NAs removal was observed during this process, toxicity was reduced by 49.3% under optimal conditions. OSPW toxicity was eliminated with the combination of ozonation at a dose of 80 mg/L followed by biodegradation, indicating that it is a promising combined OSPW treatment approach for the safe discharge to the aquatic environment. PMID:25828413

  8. On the Extraction of Aromatic Compounds from Hydrocarbons by Imidazolium Ionic Liquids

    PubMed Central

    Cassol, Cláudia C.; Umpierre, Alexandre P.; Ebeling, Günter; Ferrera, Bauer; Chiaro, Sandra S. X.; Dupont, Jairton

    2007-01-01

    The liquid-liquid equilibrium for the ternary system formed by n-octane and aromatic (alkylbenzenes) and heteroaromatic compounds (nitrogen and sulfur containing heterocyles) and 1-alkyl-3-methylimidazolium ionic liquids (ILs) associated with various anions has been investigated. The selectivity on the extraction of a specific aromatic compound is influenced by anion volume, hydrogen bond strength between the anion and the imidazolium cation and the length of the 1-methyl-3-alkylimidazolium alkyl side chain. The interaction of alkylbenzenes and sulfur heterocyles with the IL is preferentially through CH-π hydrogen bonds and the quantity of these aromatics in the IL phase decreases with the increase of the steric hindrance imposed by the substituents on the aromatic nucleus. In the case of nitrogen heterocycles the interaction occurs preferentially through N(heteroaromatic)-H(imidazolium) hydrogen bonds and the extraction process is largely controlled by the nitrogen heterocycle pKa. Competitive extraction experiments suggest that benzene, pyridine and dibenzothiophene do not compete for the same hydrogen bond sites of the IL.

  9. The studies on the aromaticity of fullerenes and their holmium endohedral compounds.

    PubMed

    Tan, Bisheng; Peng, Rufang; Li, Hongbo; Wang, Bing; Jin, Bo; Chu, Shijin; Long, Xinping

    2011-02-01

    Density functional theory BLYP/DNP was employed to optimize a series of fullerenes and their holmium endohedral compounds, including C(20), Ho@C(20), Ho(3+)@C(20), C(60), Ho@C(60), Ho(3+)@C(60),C(70), Ho@C(70), Ho(3+)@C(70) C(78), Ho@C(78), Ho(3+)@C(78), C(82),Ho@C(82) and Ho(3+)@C(82). DFT semi core pseudospot approximation was taken into consideration in the calculations of the element holmium because of its particular electronic structure. Fullerenes and their holmium endohedral compounds' aromaticity were studied in terms of structural criteria, energetic criteria, and reactivity criteria. The results indicate that the aromaticity of fullerenes was reduced when a holmium atom was introduced into the carbon cage, and the endohedral fullerenes' reactive activity enhance; but the aromaticity of the carbon cage increased when a Ho(3+) cation was encapsulated into a fullerene. Calculations of aromaticity and stability indicate that two paths can lead to the similar aim of preparing holmium endohedral fullerenes; that is, they can form from either a holmium atom or a holmium cation (Ho(3+)) reacting with fullerenes, respectively, and the latter is more favorable. PMID:20443036

  10. Native Fluorescence Detection Methods and Detectors for Naphthalene and/or Other Volatile Organic Compound Vapors

    NASA Technical Reports Server (NTRS)

    Hug, William F. (Inventor); Bhartia, Rohit (Inventor); Reid, Ray D. (Inventor); Lane, Arthur L. (Inventor)

    2014-01-01

    Naphthalene, benzene, toluene, xylene, and other volatile organic compounds have been identified as serious health hazards. This is especially true for personnel working with JP8 jet fuel and other fuels containing naphthalene as well as other hazardous volatile organic compounds (VOCs). Embodiments of the invention are directed to methods and apparatus for near-real-time in-situ detection and accumulated dose measurement of exposure to naphthalene vapor and other hazardous gaseous VOCs. The methods and apparatus employ excitation of fluorophors native or endogenous to compounds of interest using light sources emitting in the ultraviolet below 300 nm and measurement of native fluorescence emissions in distinct wavebands above the excitation wavelength. The apparatus of some embodiments are cell-phone-sized sensor/dosimeter "badges" to be worn by personnel potentially exposed to naphthalene or other hazardous VOCs. The badge sensor of some embodiments provides both real time detection and data logging of exposure to naphthalene or other VOCs of interest from which both instantaneous and accumulated dose can be determined. The badges employ a new native fluorescence based detection method to identify and differentiate VOCs. The particular focus of some embodiments are the detection and identification of naphthalene while other embodiments are directed to detection and identification of other VOCs like aromatic hydrocarbons such as benzene, toluene, and xylene.

  11. Tryptophan and tyrosine to terbium fluorescence resonance energy transfer as a method to 'map' aromatic residues and monitor docking

    SciTech Connect

    Allen, John E.; McLendon, George L. . E-mail: george.mclendon@duke.edu

    2006-11-03

    Fluorescent lanthanide ions, with large Stokes shifts and narrow emission bands, are excellent tools for the development of FRET-based assays. In this work, a terbium ion is tethered to a peptide which binds to the BIR3 domain of XIAP, an anti-apoptotic protein. Excitation of tryptophan and tyrosine residues in the BIR3 domain causes the peptide bound terbium ion to fluoresce relative to its distance from these aromatic residues. By developing ligands with terbium ions tethered at different residues, the relative terbium emission can be used to 'map' the aromatic residues within the ligand binding pocket.

  12. Biodegradation of Various Aromatic Compounds by Enriched Bacterial Cultures: Part B--Nitrogen-, Sulfur-, and Oxygen-Containing Heterocyclic Aromatic Compounds.

    PubMed

    Oberoi, Akashdeep Singh; Philip, Ligy; Bhallamudi, S Murty

    2015-07-01

    Present study focused on the biodegradation of various heterocyclic nitrogen, sulfur, and oxygen (NSO) compounds using naphthalene-enriched culture. Target compounds in the study were pyridine, quinoline, benzothiophene, and benzofuran. Screening studies were carried out using different microbial consortia enriched with specific polycyclic aromatic hydrocarbon (PAH) and NSO compounds. Among different microbial consortia, naphthalene-enriched culture was the most efficient consortium based on high substrate degradation rate. Substrate degradation rate with naphthalene-enriched culture followed the order pyridine > quinoline > benzofuran > benzothiophene. Benzothiophene and benzofuran were found to be highly recalcitrant pollutants. Benzothiophene could not be biodegraded when concentration was above 50 mg/l. It was observed that 2-(1H)-quinolinone, benzothiophene-2-one, and benzofuran-2,3-dione were formed as metabolic intermediates during biodegradation of quinoline, benzothiophene, and benzofuran, respectively. Quinoline-N and pyridine-N were transformed into free ammonium ions during the biodegradation process. Biodegradation pathways for various NSO compounds are proposed. Monod inhibition model was able to simulate single substrate biodegradation kinetics satisfactorily. Benzothiophene and benzofuran biodegradation kinetics, in presence of acetone, was simulated using a generalized multi-substrate model. PMID:26054616

  13. Structural and functional characterization of solute binding proteins for aromatic compounds derived from lignin: p-coumaric acid and related aromatic acids

    PubMed Central

    Tan, Kemin; Chang, Changsoo; Cuff, Marianne; Osipiuk, Jerzy; Landorf, Elizabeth; Mack, Jamey C.; Zerbs, Sarah; Joachimiak, Andrzej; Collart, Frank R.

    2013-01-01

    Lignin comprises 15.25% of plant biomass and represents a major environmental carbon source for utilization by soil microorganisms. Access to this energy resource requires the action of fungal and bacterial enzymes to break down the lignin polymer into a complex assortment of aromatic compounds that can be transported into the cells. To improve our understanding of the utilization of lignin by microorganisms, we characterized the molecular properties of solute binding proteins of ATP.binding cassette transporter proteins that interact with these compounds. A combination of functional screens and structural studies characterized the binding specificity of the solute binding proteins for aromatic compounds derived from lignin such as p-coumarate, 3-phenylpropionic acid and compounds with more complex ring substitutions. A ligand screen based on thermal stabilization identified several binding protein clusters that exhibit preferences based on the size or number of aromatic ring substituents. Multiple X-ray crystal structures of protein-ligand complexes for these clusters identified the molecular basis of the binding specificity for the lignin-derived aromatic compounds. The screens and structural data provide new functional assignments for these solute.binding proteins which can be used to infer their transport specificity. This knowledge of the functional roles and molecular binding specificity of these proteins will support the identification of the specific enzymes and regulatory proteins of peripheral pathways that funnel these compounds to central metabolic pathways and will improve the predictive power of sequence-based functional annotation methods for this family of proteins. PMID:23606130

  14. Structural and functional characterization of solute binding proteins for aromatic compounds derived from lignin: p-coumaric acid and related aromatic acids.

    PubMed

    Tan, Kemin; Chang, Changsoo; Cuff, Marianne; Osipiuk, Jerzy; Landorf, Elizabeth; Mack, Jamey C; Zerbs, Sarah; Joachimiak, Andrzej; Collart, Frank R

    2013-10-01

    Lignin comprises 15-25% of plant biomass and represents a major environmental carbon source for utilization by soil microorganisms. Access to this energy resource requires the action of fungal and bacterial enzymes to break down the lignin polymer into a complex assortment of aromatic compounds that can be transported into the cells. To improve our understanding of the utilization of lignin by microorganisms, we characterized the molecular properties of solute binding proteins of ATP-binding cassette transporter proteins that interact with these compounds. A combination of functional screens and structural studies characterized the binding specificity of the solute binding proteins for aromatic compounds derived from lignin such as p-coumarate, 3-phenylpropionic acid and compounds with more complex ring substitutions. A ligand screen based on thermal stabilization identified several binding protein clusters that exhibit preferences based on the size or number of aromatic ring substituents. Multiple X-ray crystal structures of protein-ligand complexes for these clusters identified the molecular basis of the binding specificity for the lignin-derived aromatic compounds. The screens and structural data provide new functional assignments for these solute-binding proteins which can be used to infer their transport specificity. This knowledge of the functional roles and molecular binding specificity of these proteins will support the identification of the specific enzymes and regulatory proteins of peripheral pathways that funnel these compounds to central metabolic pathways and will improve the predictive power of sequence-based functional annotation methods for this family of proteins. PMID:23606130

  15. A New Aromatic Compound from the Stem Bark of Terminalia catappa.

    PubMed

    Pertuit, David; Mitaine-Offer, Anne-Claire; Miyamoto, Tomofumi; Tanaka, Chiaki; Delemasure, Stéphanie; Dutartre, Patrick; Lacaille-Dubois, Marie-Aleth

    2015-06-01

    A new aromatic compound 3,4,5-trimethoxyphenyl-1-O-(4-sulfo)-β-D-glucopyranoside (1), in addition to two triterpenoid saponins (chebuloside II, arjunoglucoside II), two triterpenes (arjunolic acid and 3-betulinic acid) and sitosterol-3-O-β-D-glucopyranoside have been isolated from the barks of Terminalia catappa. Their structures have been established on the basis of spectroscopic techniques (1D/2D NMR) and MS. Their cytotoxicity and antiinflammatory activity, together with the antioxidant capacity of compound 1 were also evaluated. PMID:26197537

  16. Biogenic VOCs including monoterpenes and functionalized aromatic compounds within mid-troposphere boreal biomass burning plumes

    NASA Astrophysics Data System (ADS)

    Purvis, Ruth; Hopkins, James; Lewis, Ally; Andrews, Stephen; Punjabi, Shalini; Bauguitte, Stephan; Lee, James; Palmer, Paul; Parrington, Mark

    2013-04-01

    Boreal forest fires are a significant source of chemicals to the atmosphere including numerous VOCs (volatile organic compounds) such as monoterpenes and aromatics compounds. These compounds can have a significant effect on the formation of ozone in the atmosphere and some are implicated in the generation of secondary oxidation products, which can lead to the formation of secondary organic aerosols. Observations made during the BORTAS (Quantifying the impact of Boreal forest fires on Tropospheric oxidants using Aircraft and Satellite) campaign are presented. Data was collected onboard the UK Research Aircraft using a fast response in situ GCMS; this campaign was the first time this instrument was deployed in the field. Enhanced mixing ratios of aliphatic hydrocarbons, isoprene and monoterpenes were observed in both fresh and aged biomass burning plumes, in addition to a range of aromatic compounds such as naphthalene, benzaldehyde and acetophenone. Secondary oxidation products were also observed including methacrolein and methyl vinyl ketone. Emission ratios of organic compounds to carbon monoxide concentrations were calculated and where possible compared to literature. For most simple hydrocarbon emission ratios a very good agreement with previous measurements were observed.

  17. Time-resolved fluorescence spectra of arterial fluorescent compounds: reconstruction with the Laguerre expansion technique.

    PubMed

    Maarek, J M; Marcu, L; Snyder, W J; Grundfest, W S

    2000-02-01

    The time-resolved fluorescence spectra of the main arterial fluorescent compounds were retrieved using a new algorithm based on the Laguerre expansion of kernels technique. Samples of elastin, collagen and cholesterol were excited with a pulsed nitrogen laser and the emission was measured at 29 discrete wavelengths between 370 and 510 nm. The expansion of the fluorescence impulse response function on the Laguerre basis of functions was optimized to reproduce the observed fluorescence emission. Collagen lifetime (5.3 ns at 390 nm) was substantially larger than that of elastin (2.3 ns) and cholesterol (1.3 ns). Two decay components were identified in the emission decay of the compounds. For collagen, the decay components were markedly wavelength dependent and hydration dependent such that the emission decay became shorter at higher emission wavelengths and with hydration. The decay characteristics of elastin and cholesterol were relatively unchanged with wavelength and with hydration. The observed variations in the time-resolved spectra of elastin, collagen and cholesterol were consistent with the existence of several fluorophores with different emission characteristics. Because the compounds are present in different proportions in healthy and atherosclerotic arterial walls, characteristic differences in their time-resolved emission spectra could be exploited to assess optically the severity of atherosclerotic lesions. PMID:10687392

  18. Investigation of aromatic compound degradation under atmospheric conditions in the outdoor simulation chamber SAPHIR

    NASA Astrophysics Data System (ADS)

    Nehr, Sascha; Bohn, Birger; Rohrer, Franz; Tillmann, Ralf; Wegener, Robert; Dorn, Hans-Peter; Häseler, Rolf; Brauers, Theo; Wahner, Andreas

    2010-05-01

    Ozone is produced in the lower troposphere by the OH-initiated photooxidation of volatile organic compounds in the presence of NOx. Aromatic hydrocarbons from anthropogenic sources are a major contributor to the OH-reactivity and thus to ozone formation in urban areas [1]. Moreover, their degradation leads to formation of secondary organic aerosol. Aromatic compounds are therefore important trace constituents with regard to air quality. We will present the results of photooxidation experiments which were conducted in the atmospheric simulation chamber SAPHIR at Forschungszentrum Jülich. The experiments were designed to investigate the degradation mechanisms of benzene and p-xylene, which are among the most abundant aromatics in urban air samples. Benzene and p-xylene were selected because they have high structural symmetry which limits the number of potential isomers of secondary products. The experiments were performed under low-NOx-conditions (≤ 2 ppb). SAPHIR was equipped with instruments for the measurement of the parent aromatics and their major oxidation products, OH radicals, important radical precursors (O3, HONO, HCHO), photolysis frequencies and particulate matter. As shown in previous studies, simulation chamber data from the photooxidation of aromatics cannot be explained satisfactorily with current photochemistry mechanisms. For example the MCMv3.1 tends to overestimate the ozone-concentration and to underestimate the OH-concentration [2]. In this study, we will contrast model calculations with experimental results to check if similar discrepancies can be observed in SAPHIR and how they can be resolved. Based on the results of this preparatory study, further simulation chamber experiments with special emphasis on the radical budget are scheduled in 2010. References: [1] J. G. Calvert, R. Atkinson, K.H. Becker, R.M. Kamens, J.H. Seinfeld, T.J. Wallington, G. Yarwood: The mechanisms of atmospheric oxidation of aromatic hydrocarbons, Oxford University

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

    DOEpatents

    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.

  20. Double-tagged fluorescent bacterial bioreporter for the study of polycyclic aromatic hydrocarbon diffusion and bioavailability.

    PubMed

    Tecon, Robin; Binggeli, Olivier; van der Meer, Jan R

    2009-09-01

    Bacterial degradation of polycyclic aromatic hydrocarbons (PAHs), ubiquitous contaminants from oil and coal, is typically limited by poor accessibility of the contaminant to the bacteria. In order to measure PAH availability in complex systems, we designed a number of diffusion-based assays with a double-tagged bacterial reporter strain Burkholderia sartisoli RP037-mChe. The reporter strain is capable of mineralizing phenanthrene (PHE) and induces the expression of enhanced green fluorescent protein (eGFP) as a function of the PAH flux to the cell. At the same time, it produces a second autofluorescent protein (mCherry) in constitutive manner. Quantitative epifluorescence imaging was deployed in order to record reporter signals as a function of PAH availability. The reporter strain expressed eGFP proportionally to dosages of naphthalene or PHE in batch liquid cultures. To detect PAH diffusion from solid materials the reporter cells were embedded in 2 cm-sized agarose gel patches, and fluorescence was recorded over time for both markers as a function of distance to the PAH source. eGFP fluorescence gradients measured on known amounts of naphthalene or PHE served as calibration for quantifying PAH availability from contaminated soils. To detect reporter gene expression at even smaller diffusion distances, we mixed and immobilized cells with contaminated soils in an agarose gel. eGFP fluorescence measurements confirmed gel patch diffusion results that exposure to 2-3 mg lampblack soil gave four times higher expression than to material contaminated with 10 or 1 (mg PHE) g(-1). PMID:19490030

  1. Ultraviolet-stimulated fluorescence and phosphorescence of aromatic hydrocarbons in water ice.

    PubMed

    Johnson, Paul V; Hodyss, Robert; Bolser, Diana K; Bhartia, Rohit; Lane, Arthur L; Kanik, Isik

    2011-03-01

    A principal goal of astrobiology is to detect and inventory the population of organic compounds on extraterrestrial bodies. Targets of specific interest include the wealth of icy worlds that populate our Solar System. One potential technique for in situ detection of organics trapped in water ice matrices involves ultraviolet-stimulated emission from these compounds. Here, we report a preliminary investigation into the feasibility of this concept. Specifically, fluorescence and phosphorescence of pure benzene ice and 1% mixtures of benzene, toluene, p-xylene, m-xylene, and o-xylene in water ice, respectively, were studied at temperatures ranging from ∼17 K up to 160 K. Spectra were measured from 200-500 nm (50,000-20,000 cm(-1)) while ice mixtures were excited at 248.6 nm. The temperature dependence of the fluorescence and phosphorescence intensities was found to be independent of the thermal history and phase of the ice matrix in all cases examined. All phosphorescent emissions were found to decrease in intensity with increasing temperature. Similar behavior was observed for fluorescence in pure benzene, while the observed fluorescence intensity in water ices was independent of temperature. PMID:21417944

  2. A fluorescent reporter detects details of aromatic ligand interference in drug-binding sites of human serum albumin.

    PubMed

    Dobretsov, Gennady; Smolina, Natalia; Syrejshchikova, Tatiana; Brilliantova, Varvara; Uzbekov, Marat

    2016-09-01

    Human serum albumin (HSA) transports many ligands including small aromatic molecules: metabolites, drugs etc. Phenylbutazone is an anti-inflammatory drug, which binds to the drug-binding site I of HSA. Its interaction with this site has been studied using a fluorescent dye, CAPIDAN, whose fluorescence in serum originates from HSA and is sensitive to the changes in HSA site I in some diseases. Its fluorescence in HSA solutions is strongly suppressed by phenylbutazone. This phenomenon seems to be a basic sign of a simple drug-dye competition. However, a more detailed study of the time-resolved fluorescence decay of CAPIDAN has shown that phenylbutazone lowers fluorescence without changing the total amount of bound dye. In brief, the HSA-bound dye forms three populations due to three types of environment at the binding sites. The first two populations probably have a rather strong Coulomb interaction with the positive charge of residues Arginine 218 or Arginine 222 in site I and are responsible for approximately 90% of the total fluorescence. Phenylbutazone blocks this interaction and therefore lowers this fluorescence. At the same time the binding of the third population increases considerably in the presence of phenylbutazone, and, as a result, the actual number of bound dye molecules remains almost unchanged despite the ligand competition. So, time resolved fluorescence of the reporter allows to observe details of interactions and interference of aromatic ligands in drug binding site I of HSA both in isolated HSA and in serum. PMID:27318089

  3. Enhancing trichloroethylene degradation using non-aromatic compounds as growth substrates.

    PubMed

    Kim, Seungjin; Hwang, Jeongmin; Chung, Jinwook; Bae, Wookeun

    2014-06-30

    The effect of non-aromatic compounds on the trichloroethylene (TCE) degradation of toluene-oxidizing bacteria were evaluated using Burkholderia cepacia G4 that expresses toluene 2-monooxygenase and Pseudomonas putida that expresses toluene dioxygenase. TCE degradation rates for B. cepacia G4 and P. putida with toluene alone as growth substrate were 0.144 and 0.123 μg-TCE/mg-protein h, respectively. When glucose, acetate and ethanol were fed as additional growth substrates, those values increased up to 0.196, 0.418 and 0.530 μg-TCE/mg-protein h, respectively for B. cepacia G4 and 0.319, 0.219 and 0.373 μg-TCE/mg-protein h, respectively for P. putida. In particular, the addition of ethanol resulted in a high TCE degradation rate regardless of the initial concentration. The use of a non-aromatic compound as an additional substrate probably enhanced the TCE degradation because of the additional supply of NADH that is consumed in co-metabolic degradation of TCE. Also, it is expected that the addition of a non-aromatic substrate can reduce the necessary dose of toluene and, subsequently, minimize the potential competitive inhibition upon TCE co-metabolism by toluene. PMID:24857894

  4. Conjugative transfer of preferential utilization of aromatic compounds from Pseudomonas putida CSV86.

    PubMed

    Basu, Aditya; Phale, Prashant S

    2008-02-01

    Pseudomonas putida CSV86 utilizes naphthalene (Nap), salicylate (Sal), benzyl alcohol (Balc), and methylnaphthalene (MN) preferentially over glucose. Methylnaphthalene is metabolized by ring-hydroxylation as well as side-chain hydroxylation pathway. Although the degradation property was found to be stable, the frequency of obtaining Nap(-)Sal(-)MN(-)Balc(-) phenotype increased to 11% in the presence of curing agents. This property was transferred by conjugation to Stenotrophomonas maltophilia CSV89 with a frequency of 7 x 10(-8) per donor cells. Transconjugants were Nap(+)Sal(+)MN(+)Balc(+) and metabolized MN by ring- as well as side-chain hydroxylation pathway. Transconjugants also showed the preferential utilization of aromatic compounds over glucose indicating transfer of the preferential degradation property. The transferred properties were lost completely when transconjugants were grown on glucose or 2YT. Attempts to detect and isolate plasmid DNA from CSV86 and transconjugants were unsuccessful. Transfer of degradation genes and its subsequent loss from the transconjugants was confirmed by PCR using primers specific for 1,2-dihydroxynaphthalene dioxygenase and catechol 2,3-dioxygenase (C23O) as well as by DNA-DNA hybridizations using total DNA as template and C23O PCR fragment as a probe. These results indicate the involvement of a probable conjugative element in the: (i) metabolism of aromatic compounds, (ii) ring- and side-chain hydroxylation pathways for MN, and (iii) preferential utilization of aromatics over glucose. PMID:17487554

  5. Analysis of industrial contaminants in indoor air: part 1. Volatile organic compounds, carbonyl compounds, polycyclic aromatic hydrocarbons and polychlorinated biphenyls.

    PubMed

    Barro, Ruth; Regueiro, Jorge; Llompart, María; Garcia-Jares, Carmen

    2009-01-16

    This article reviews recent literature on the analysis of industrial contaminants in indoor air in the framework of the REACH project, which is mainly intended to improve protection of human health and the environment from the risks of more than 34 millions of chemical substances. Industrial pollutants that can be found in indoor air may be of very different types and origin, belonging to the volatile organic compounds (VOCs) and semivolatile organic compounds (SVOCs) categories. Several compounds have been classified into the priority organic pollutants (POPs) class such as polychlorinated biphenyls (PCBs), polychlorinated dibenzo-p-dioxins and furans (PCDD/PCDFs) and related polychlorinated compounds, and polycyclic aromatic hydrocarbons (PAHs). Many of these compounds are partially associated to the air gas phase, but also to the suspended particulate matter. Furthermore, settled dust can act as a concentrator for the less volatile pollutants and has become a matrix of great concern for indoors contamination. Main literature considered in this review are papers from the last 10 years reporting analytical developments and applications regarding VOCs, aldehydes and other carbonyls, PCBs, PCDDs, PCDFs, and PAHs in the indoor environment. Sample collection and pretreatment, analyte extraction, clean-up procedures, determination techniques, performance results, as well as compound concentrations in indoor samples, are summarized and discussed. Emergent contaminants and pesticides related to the industrial development that can be found in indoor air are reviewed in a second part in this volume. PMID:19019381

  6. Degradation and formation of polycyclic aromatic compounds during bioslurry treatment of an aged gasworks soil.

    PubMed

    Lundstedt, Staffan; Haglund, Peter; Oberg, Lars

    2003-07-01

    The goals of this study were to investigate the relative degradation rates of polycyclic aromatic compounds (PACs) in contaminated soil, and to assess whether persistent oxidation products are formed during their degradation. Samples were taken on five occasions during a pilot-scale bioslurry treatment of soil from a former gasworks site. More than 100 PACs were identified in the soil, including unsubstituted polycyclic aromatic hydrocarbons (PAHs), alkylated PAHs (alkyl-PAHs), heterocyclic PACs, and oxygenated PAHs (oxy-PAHs), such as ketones, quinones, and coumarins. During the treatment, the low molecular weight PAHs and heterocyclics were degraded faster than the high molecular weight compounds. The unsubstituted PAHs also appear to have degraded more quickly than the corresponding alkyl-PAHs and nitrogen-containing heterocyclics. No new oxidation products that were not present in the untreated soil were identified after the soil treatment. However, oxy-PAHs that were present in the untreated soil were generally degraded more slowly than the parent compounds, suggesting that they were formed during the treatment or that they are more persistent. Two oxidation products, 1-acenaphthenone and 4-oxapyrene-5-one, were found at significantly higher concentrations at the end of the study. Because oxy-PAHs can be acutely toxic, mutagenic, or carcinogenic, we suggest that this group of compounds should also be monitored during the treatment of PAH-contaminated soil. PMID:12836964

  7. Production of laccase isoforms by Pleurotus pulmonarius in response to presence of phenolic and aromatic compounds.

    PubMed

    de Souza, Cristina Giatti Marques; Tychanowicz, Giovana Kirst; de Souza, Daniela Farani; Peralta, Rosane Marina

    2004-01-01

    The effect of several phenolic and aromatic monomers structurally-related to lignin on production of laccase by the white rot fungus P. pulmonarius (Fr.) Quélet has been studied. In the absence of an inducer, laccase was maximally produced after depletion of carbon and nitrogen sources. Among 15 phenolic and aromatic compounds tested, ferulic acid and vanillin were the most efficient inducers, increasing the production of laccase activity up to 10 times. A mixture of ferulic acid and vanillin was more efficient to induce the production of laccase than the isolated phenolics. At least three laccase isoforms designated as lcc1, lcc2 and lcc3 were identified by eletrophoretic analysis of P. pulmonarius culture filtrates. The lcc1 and lcc2 isoforms were produced by non-induced cultures, while lcc3 was found only in induced-culture filtrates. PMID:15069672

  8. Comprehensive NO-dependent study of the products of the oxidation of atmospherically relevant aromatic compounds.

    PubMed

    Birdsall, Adam W; Elrod, Matthew J

    2011-06-01

    A comprehensive product study, performed via the turbulent flow chemical ionization mass spectrometry (TF-CIMS) technique, of the primary OH-initiated oxidation of many of the atmospherically abundant aromatic compounds was performed. The bicyclic peroxy radical intermediate, a key proposed intermediate species in the Master Chemical Mechanism (MCM) for the atmospheric oxidation of aromatics, was detected in all cases, as were stable bicyclic species. The NO product yield dependences suggest a potential role for bicyclic peroxy radical + HO(2) reactions at high HO(2)/NO ratios, which are postulated to be a possible source of the inconsistencies between previous environmental chamber results and predictions from the MCM for ozone production and OH reactivity. The TF-CIMS product yield results are also compared to previous environment chamber results and to the latest MCM parametrization. PMID:21553858

  9. Aromatic-Hydroxyl Interaction of a Lignin Model Compound on SBA-15, Present at Pyrolysis Temperatures

    DOE PAGESBeta

    Kandziolka, III, Michael V.; Kidder, Michelle; Gill, Lance W.; Wu, Zili; Savara, Aditya Ashi

    2014-07-14

    An aromatic alpha-aryl ether compound (a benzyl phenyl ether analogue) was covalently grafted to mesoporous silica SBA-15, to create BPEa-SBA-15. The BPEa-SBA-15 was subjected to successive heating cycles up to 600 °C, with in situ monitoring by DRIFTS. It was found that the toluene moiety coordinates to SBA-15 surface silanol hydroxyl groups via an aromatic–hydroxyl interaction. This interaction is evidenced by a red-shift of the aromatic C–H stretches, as well as a red-shift and broadening of the surface hydroxyl O–H stretches, which are features characteristic of a hydrogen bond. These features remain present during heating until ~400 °C whereupon themore » ether linkage of BPEa-SBA-15 is cleaved, accompanied by loss of the toluene moiety.« less

  10. Aromatic-Hydroxyl Interaction of a Lignin Model Compound on SBA-15, Present at Pyrolysis Temperatures

    SciTech Connect

    Kandziolka, III, Michael V.; Kidder, Michelle; Gill, Lance W.; Wu, Zili; Savara, Aditya Ashi

    2014-07-14

    An aromatic alpha-aryl ether compound (a benzyl phenyl ether analogue) was covalently grafted to mesoporous silica SBA-15, to create BPEa-SBA-15. The BPEa-SBA-15 was subjected to successive heating cycles up to 600 °C, with in situ monitoring by DRIFTS. It was found that the toluene moiety coordinates to SBA-15 surface silanol hydroxyl groups via an aromatic–hydroxyl interaction. This interaction is evidenced by a red-shift of the aromatic C–H stretches, as well as a red-shift and broadening of the surface hydroxyl O–H stretches, which are features characteristic of a hydrogen bond. These features remain present during heating until ~400 °C whereupon the ether linkage of BPEa-SBA-15 is cleaved, accompanied by loss of the toluene moiety.

  11. Quinones and Aromatic Chemical Compounds in Particulate Matter Induce Mitochondrial Dysfunction: Implications for Ultrafine Particle Toxicity

    PubMed Central

    Xia, Tian; Korge, Paavo; Weiss, James N.; Li, Ning; Venkatesen, M. Indira; Sioutas, Constantinos; Nel, Andre

    2004-01-01

    Particulate pollutants cause adverse health effects through the generation of oxidative stress. A key question is whether these effects are mediated by the particles or their chemical compounds. In this article we show that aliphatic, aromatic, and polar organic compounds, fractionated from diesel exhaust particles (DEPs), exert differential toxic effects in RAW 264.7 cells. Cellular analyses showed that the quinone-enriched polar fraction was more potent than the polycyclic aromatic hydrocarbon (PAH)–enriched aromatic fraction in O2•− generation, decrease of membrane potential (ΔΨm), loss of mitochondrial membrane mass, and induction of apoptosis. A major effect of the polar fraction was to promote cyclosporin A (CsA)–sensitive permeability transition pore (PTP) opening in isolated liver mitochondria. This opening effect is dependent on a direct effect on the PTP at low doses as well as on an effect on ΔΨm at high doses in calcium (Ca2+)-loaded mitochondria. The direct PTP effect was mimicked by redox-cycling DEP quinones. Although the aliphatic fraction failed to perturb mitochondrial function, the aromatic fraction increased the Ca2+ retention capacity at low doses and induced mitochondrial swelling and a decrease in ΔΨm at high doses. This swelling effect was mostly CsA insensitive and could be reproduced by a mixture of PAHs present in DEPs. These chemical effects on isolated mitochondria could be reproduced by intact DEPs as well as ambient ultrafine particles (UFPs). In contrast, commercial polystyrene nanoparticles failed to exert mitochondrial effects. These results suggest that DEP and UFP effects on the PTP and ΔΨm are mediated by adsorbed chemicals rather than the particles themselves. PMID:15471724

  12. Langmuir films of asphaltene model compounds and their fluorescent properties.

    PubMed

    Nordgård, Erland L; Landsem, Eva; Sjöblom, Johan

    2008-08-19

    The relationship between the physicochemical properties of asphaltenes and asphaltene structure is an issue of increasing focus. Surface pressure-area isotherms of asphaltene model compounds have been investigated to gain more knowledge of their arrangement at an aqueous surface. Variations in interfacial activity have been correlated to proposed arrangements. The presence of a carboxylic acid has shown to be crucial for their interfacial activity and film properties. The acid group directs the molecules normal to the surface, forming a stable monolayer film. The high stability was absent when no acidic groups were present. Fluorescence spectra of deposited Langmuir-Blodgett films showed only the presence of the excimer emission for thin films of acidic model compounds, indicating a close face-to-face arrangement of the molecules. Time-correlated single photon counting (TCSPC) of the model compounds in toluene indicated the presence of aggregates for two of four compounds at low concentrations. However, a sudden drop of interfacial tension observed could not be correlated to the aggregation. Instead, aggregation induced by addition of a "poor" solvent showed decreased interfacial activity when aggregated due to decrease of monomers in bulk. The findings regarding these asphaltene model compounds and their structural differences show the great effect an acidic group has on their physicochemical properties. PMID:18652499

  13. Uptake of polycyclic aromatic hydrocarbon compounds by the gills of the bivalve mollusk Elliptio complanata.

    PubMed

    Birdsall, K; Kukor, J J; Cheney, M A

    2001-02-01

    Polycyclic aromatic hydrocarbons (PAHs) and herbicides are important contaminants of world water systems with effects on aquatic organisms. The uptake of naphthalene, anthracene, and chrysene by gills of the bivalve mollusk Elliptio complanata was determined. Additionally, the effects of paraquat, atrazine, alachlor, 2,4-dichlorophenoxyacetic acid (2,4-D), and 2,4-dinitrophenol on the uptake of these compounds were also determined. The results indicate (1) the uptake of anthracene is approximately equivalent to that of chrysene and the uptake of either of these compounds is higher than that of naphthalene; (2) comparisons of uptakes with that of inulin, which occupies only extracellular space, show that all compounds studied are taken up; (3) the uptakes of naphthalene, anthracene, and chrysene are initially altered by the presence of herbicides such as paraquat, alachlor, 2,4-D, atrazine, and 2,4-dinitrophenol. PMID:11351430

  14. Bioactive Compounds Derived from the Yeast Metabolism of Aromatic Amino Acids during Alcoholic Fermentation

    PubMed Central

    Guillamon, Jose Manuel; Torija, Maria Jesus; Beltran, Gemma; Troncoso, Ana M.; Garcia-Parrilla, M. Carmen

    2014-01-01

    Metabolites resulting from nitrogen metabolism in yeast are currently found in some fermented beverages such as wine and beer. Their study has recently attracted the attention of researchers. Some metabolites derived from aromatic amino acids are bioactive compounds that can behave as hormones or even mimic their role in humans and may also act as regulators in yeast. Although the metabolic pathways for their formation are well known, the physiological significance is still far from being understood. The understanding of this relevance will be a key element in managing the production of these compounds under controlled conditions, to offer fermented food with specific enrichment in these compounds or even to use the yeast as nutritional complements. PMID:24895623

  15. Potential aromatic compounds as markers to differentiate between Tuber melanosporum and Tuber indicum truffles.

    PubMed

    Culleré, Laura; Ferreira, Vicente; Venturini, María E; Marco, Pedro; Blanco, Domingo

    2013-11-01

    The Tuber indicum (Chinese truffle) and Tuber melanosporum (Black truffle) species are morphologically very similar but their aromas are very different. The black truffle aroma is much more intense and complex, and it is consequently appreciated more gastronomically. This work tries to determine whether the differences between the aromatic compounds of both species are sufficiently significant so as to apply them to fraud detection. An olfactometric evaluation (GC-O) of T. indicum was carried out for the first time. Eight important odorants were identified. In order of aromatic significance, these were: 1-octen-3-one and 1-octen-3-ol, followed by two ethyl esters (ethyl isobutyrate and ethyl 2-methylbutyrate), 3-methyl-1-butanol, isopropyl acetate, and finally the two sulfides dimethyldisulfide (DMDS) and dimethylsulfide (DMS). A comparison of this aromatic profile with that of T. melanosporum revealed the following differences: T. indicum stood out for the significant aromatic contribution of 1-octen-3-one and 1-octen-3-ol (with modified frequencies (MF%) of 82% and 69%, respectively), while in the case of T. melanosporum both had modified frequencies of less than 30%. Ethyl isobutyrate, ethyl 2-methylbutyrate and isopropyl acetate were also significantly higher, while DMS and DMDS had low MF (30-40%) compared to T. melanosporum (>70%). The volatile profiles of both species were also studied by means of headspace solid-phase microextraction (HS-SPME-GC-MS). This showed that the family of C8 compounds (3-octanone, octanal, 1-octen-3-one, 3-octanol and 1-octen-3-ol) is present in T. indicum at much higher levels. The presence of 1-octen-3-ol was higher by a factor of about 100, while 1-octen-3-one was detected in T. indicum only (there was no chromatographic signal in T. melanosporum). As well as showing the greatest chromatographic differences, these two compounds were also the most powerful from the aromatic viewpoint in the T. indicum olfactometry. Therefore

  16. Characterization of Transport Proteins for Aromatic Compounds Derived from Lignin: Benzoate Derivative Binding Proteins

    PubMed Central

    Michalska, Karolina; Chang, Changsoo; Mack, Jamey C.; Zerbs, Sarah; Joachimiak, Andrzej; Collart, Frank R.

    2013-01-01

    In vitro growth experiments have demonstrated that aromatic compounds derived from lignin can be metabolized and represent a major carbon resource for many soil bacteria. However, the proteins that mediate the movement of these metabolites across the cell membrane have not been thoroughly characterized. To address this deficiency, we used a library representative of lignin degradation products and a thermal stability screen to determine ligand specificity for a set of solute-binding proteins (SBPs) from ATP-binding cassette (ABC) transporters. The ligand mapping process identified a set of proteins from Alphaproteobacteria that recognize various benzoate derivatives. Seven high-resolution crystal structures of these proteins in complex with four different aromatic compounds were obtained. The protein–ligand complexes provide details of molecular recognition that can be used to infer binding specificity. This structure–function characterization provides new insight for the biological roles of these ABC transporters and their SBPs, which had been previously annotated as branched-chain amino-acid-binding proteins. The knowledge derived from the crystal structures provides a foundation for development of sequencebased methods to predict the ligand specificity of other uncharacterized transporters. These results also demonstrate that Alphaproteobacteria possess a diverse set of transport capabilities for lignin-derived compounds. Characterization of this new class of transporters improves genomic annotation projects and provides insight into the metabolic potential of soil bacteria. PMID:22925578

  17. Accumulation and elimination of 16 polycyclic aromatic compounds in the earthworm (Eisenia fetida).

    PubMed

    Matscheko, Nadja; Lundstedt, Staffan; Svensson, Linda; Harju, Mikael; Tysklind, Mats

    2002-08-01

    Accumulation and elimination of different polycyclic aromatic compounds (PACs) were studied in earthworms (Eisenia fetida) exposed to contaminated soil from an old gasworks site. In total, 12 polycyclic aromatic hydrocarbons (PAHs), two N- and S-heterocyclic PACs, and two PAC-quinones were included in the study. Peak-shaped accumulation curves were found for many of the compounds. After 19 d of exposure, the ratio between concentrations in worm lipids and soil organic matter was 0.02 on average. The half-lives of the PACs were relatively long, between 2 and 11 d. The elimination rate constants, k2, correlated both with literature-derived octanol-water partition coefficients (Kow) for PAHs (r2 = 0.93) and the computed polarizability (r2 = 0.88) of all the compounds. The elimination rate constants of PAHs are comparable to those of PCBs found in earlier studies, and the linear regression coefficient, r2, of k2 against Kow for PAHs and PCBs together was 0.93. PMID:12152775

  18. Predicting adsorption of aromatic compounds by carbon nanotubes based on quantitative structure property relationship principles

    NASA Astrophysics Data System (ADS)

    Rahimi-Nasrabadi, Mehdi; Akhoondi, Reza; Pourmortazavi, Seied Mahdi; Ahmadi, Farhad

    2015-11-01

    Quantitative structure property relationship (QSPR) models were developed to predict the adsorption of aromatic compounds by carbon nanotubes (CNTs). Five descriptors chosen by combining self-organizing map and stepwise multiple linear regression (MLR) techniques were used to connect the structure of the studied chemicals with their adsorption descriptor (K∞) using linear and nonlinear modeling techniques. Correlation coefficient (R2) of 0.99 and root-mean square error (RMSE) of 0.29 for multilayered perceptron neural network (MLP-NN) model are signs of the superiority of the developed nonlinear model over MLR model with R2 of 0.93 and RMSE of 0.36. The results of cross-validation test showed the reliability of MLP-NN to predict the K∞ values for the aromatic contaminants. Molar volume and hydrogen bond accepting ability were found to be the factors much influencing the adsorption of the compounds. The developed QSPR, as a neural network based model, could be used to predict the adsorption of organic compounds by CNTs.

  19. Characterization of a fluorescent compound isolated from Legionella pneumophila

    SciTech Connect

    Swanson, S.J.

    1987-01-01

    Legionella pneumophila requires the presence of amino acids for growth and utilizes them for energy. Along with other amino acids, either phenylalanine or tyrosine is essential for the growth of the organism and tyrosine has been identified as an energy source. When L. pneumophila is grown in the presence of tyrosine, a brown melanin-like pigment is produced. A green fluorescent pigment, fg2, was isolated from centrifuged culture fluid after the organism was grown in the presence of tyrosine. Fg2 is water soluble with a molecular weight of 152 as determined by mass spectral analysis. A mutant of L. pneumophila unable to produce fg2 was isolated to assist in elucidation of the biosynthesis of fg2. Radiolabeling experiments were utilized to conclude that neither tyrosine nor any other amino acid was a precursor in the biosynthesis of fg2. Shikimic acid, an intermediate in tyrosine biosynthesis, was found to also be an intermediate in the biosynthesis of fg2. A series of experiments in which L. pneumophila was grown in a chemically defined medium containing various combinations of aromatic amino acids determined that fg2 and the brown pigment always occur in tandem.

  20. Charge-transfer complexes of pyrimidine Schiff bases with aromatic nitro compounds

    NASA Astrophysics Data System (ADS)

    Issa, Yousry M.; El Ansary, A. L.; Sherif, O. E.; Hassib, H. B.

    2011-08-01

    Charge-transfer (CT) complexes of pyrimidine Schiff bases, derived from condensation of 2-aminopyrimidine and substituted benzaldehydes, with some aromatic polynitro compounds were prepared and investigated using IR, UV, visible and 1H NMR spectroscopy. For all solid complexes, the main interaction between the donor and acceptor molecules takes place through the π-π* interaction. Strong and some weak acidic acceptors, in addition interact through proton transfer from the acceptor molecule to the basic centre of the electron donor. Also, an n-π* transition was detected in some complexes.

  1. Charge-transfer complexes of pyrimidine Schiff bases with aromatic nitro compounds.

    PubMed

    Issa, Yousry M; el-Ansary, A L; Sherif, O E; Hassib, H B

    2011-08-01

    Charge-transfer (CT) complexes of pyrimidine Schiff bases, derived from condensation of 2-aminopyrimidine and substituted benzaldehydes, with some aromatic polynitro compounds were prepared and investigated using IR, UV, visible and (1)H NMR spectroscopy. For all solid complexes, the main interaction between the donor and acceptor molecules takes place through the π-π* interaction. Strong and some weak acidic acceptors, in addition interact through proton transfer from the acceptor molecule to the basic centre of the electron donor. Also, an n-π* transition was detected in some complexes. PMID:21531169

  2. Flash Vacuum Pyrolysis of Lignin Model Compounds: Reaction Pathways of Aromatic Methoxy Groups

    SciTech Connect

    Britt, P.F.; Buchanan, A.C., III; Martineau, D.R.

    1999-03-21

    Currently, there is interest in utilizing lignin, a major constituent of biomass, as a renewable source of chemicals and fuels. High yields of liquid products can be obtained from the flash or fast pyrolysis of biomass, but the reaction pathways that lead to product formation are not understood. To provide insight into the primary reaction pathways under process relevant conditions, we are investigating the flash vacuum pyrolysis (FVP) of lignin model compounds at 500 C. This presentation will focus on the FVP of {beta}-ether linkages containing aromatic methoxy groups and the reaction pathways of methoxy-substituted phenoxy radicals.

  3. Sono-bromination of aromatic compounds based on the ultrasonic advanced oxidation processes.

    PubMed

    Fujita, Mitsue; Lévêque, Jean-Marc; Komatsu, Naoki; Kimura, Takahide

    2015-11-01

    A novel, mild "sono-halogenation" of various aromatic compounds with potassium halide was investigated under ultrasound in a biphasic carbon tetrachloride/water medium. The feasibility study was first undertaken with the potassium bromide and then extended to chloride and iodide analogues. This methodology could be considered as a new expansion of the ultrasonic advanced oxidation processes (UAOPs) into a synthetic aspect as the developed methodology is linked to the sonolytic disappearance of carbon tetrachloride. Advantages of the present method are not only that the manipulation of the bromination is simple and green, but also that the halogenating agents used are readily available, inexpensive, and easy-handling. PMID:26186842

  4. Isolation and identification of aromatic compounds in Lion's Mane Mushroom and their anticancer activities.

    PubMed

    Li, Wei; Zhou, Wei; Kim, Eun-Ji; Shim, Sang Hee; Kang, Hee Kyoung; Kim, Young Ho

    2015-03-01

    Lion's Mane Mushroom (Hericium erinaceum) is a traditional edible mushroom widely used in culinary applications and as an herbal medicine in East Asian countries. In the present study, two new aromatic compounds, hericerin A (1) and isohericenone J (5), along with five known compounds, isoericerin (2), hericerin (3), N-De phenylethyl isohericerin (4), hericenone J (6), and 4-[3',7'-dimethyl-2',6'-octadienyl]-2-formyl-3-hydroxy-5-methyoxybenzylalcohol (7), were isolated from a methanol extract of the fruiting bodies of H. erinaceum. The chemical structures of the compounds were determined from mass spectra and 1D- and 2D NMR spectroscopy. The anticancer effects of the isolated compounds were examined in HL-60 human acute promyelocytic leukaemia cells. Hericerin A (1) and hericerin (3) significantly reduced cell proliferation with IC50 values of 3.06 and 5.47 μM, respectively. These same compounds also induced apoptosis of HL-60 cells, accompanied by time-dependent down-regulation of p-AKT and c-myc levels. These data suggest that compounds 1 and 3 from H. erinaceum are suitable for use in potential cancer treatments. PMID:25306354

  5. Comparison of HPLC-MS interfaces in the determination of heterocyclic polycyclic aromatic compounds

    SciTech Connect

    Thomas, D.; Sim, P.G.; Benoit, F.M.

    1995-12-31

    Polycyclic aromatic compounds (PACs) are generally regarded as one of the most widely disseminated groups of chemical carcinogens. In this work, the authors are interested in the determination of some of the heteroatom substituted PACs, particularly those containing nitrogen (PANHs) or sulfur (PASHs) in the aromatic ring structure. The reason for interest in these compounds is the extreme carcinogenicity of many of them. Further, the relative carcinogenicity can vary markedly between different members of a set of isomeric compounds. Any reliable assessment of the hazards associated with exposure to mixtures of PACs must, therefore, include analysis of the levels of these compounds in the mixture. The analytical technique used must also yield information about the relative amounts of different isomeric compounds. The sample chosen for this study is an extract of PACs from the Sydney Tar Ponds, Sydney, Nova Scotia, Canada. The Tar Ponds represent the end result of approximately 80 years of the uncontrolled discharge of effluent from an industrial coking operation into a tidal lagoon. It is thus a rich source of PAC mixtures. In the present work, the authors have applied two HPLC-MS methods to the characterization of the PASH content of tar pond sample fractions. The methods differed in the nature of the interface between the HPLC and the MS, and in the ionization process. The two techniques studied were the moving belt with EI ionization, and the heated nebulizer with APCI. Comparison was made on the basis of a number of criteria, including ease of use (and of automation), quality of mass spectra provided, preservation of chromatographic integrity, and sensitivity.

  6. Controlling the Adsorption of Aromatic Compounds on Pt(111) with Oxygenate Substituents: From DFT to Simple Molecular Descriptors.

    PubMed

    Réocreux, Romain; Huynh, Minh; Michel, Carine; Sautet, Philippe

    2016-06-01

    Aromatic chemistry on metallic surfaces is involved in many processes within the contexts of biomass valorization, pollutant degradation, or corrosion protection. Albeit theoretically and experimentally challenging, knowing the structure and the stability of aromatic compounds on such surfaces is essential to understand their properties. To gain insights on this topic, we performed periodic ab initio calculations on Pt(111) to determine a set of simple molecular descriptors that predict both the stability and the structure of aromatic adsorbates substituted with alkyl and alkoxy (or hydroxy) groups. While the van der Waals (vdW) interaction is controlled by the molecular weight and the deformation energy by both the nature and the relative position of the substituents to the surface, the chemical bonding can be correlated to the Hard and Soft Acids and Bases (HSAB) interaction energy. This work gives general insights on the interaction of aromatic compounds with the Pt(111) surface. PMID:27206155

  7. Nature of the mutagenicity and carcinogenicity of nitrated, aromatic compounds in the environment

    SciTech Connect

    Tokiwa, H.; Nakagawa, R.; Horikawa, K.; Ohkubo, A.

    1987-08-01

    Gaseous substances such as nitrogen dioxide (NO/sub 2/) and sulfur dioxide (SO/sub 2/) stimulate the process of nitration of polycyclic aromatic hydrocarbons, and the transformation products display a broad spectrum of mutagenicity, genotoxicity, and carcinogenicity. Bacterial mutation by nitroarenes is specific. Tetracyclic nitroarenes are thought to be the most mutagenic compounds in the Salmonella test system, and some are carcinogenic in rats and mice. Furthermore, it was found that the mutational nitroarenes produced mostly DNA damage, which is subject to recombination repair in the rec assay system using Bacillus subtilis. Nitroarenes in the environment seem to be ubiquitous; the majority of the compounds are emitted directly from diesel emissions, kerosene heaters, and gas and liquefied-gas burners or heaters. In nitroarenes induced during incomplete combustion, nitropyrene and nitrofluoranthene derivatives are the most important mutagens/carcinogens for determining the chronic toxicity of nitroarenes overall.

  8. Copper-catalyzed formal C - H carboxylation of aromatic compounds with carbon dioxide through arylaluminum intermediates.

    PubMed

    Ueno, Atsushi; Takimoto, Masanori; O, Wylie W N; Nishiura, Masayoshi; Ikariya, Takao; Hou, Zhaomin

    2015-04-01

    The C - H bond carboxylation of various aromatic compounds with CO2 was achieved by the deprotonative alumination with a mixed alkyl amido lithium aluminate compound iBu3 Al(TMP)Li followed by the NHC-copper-catalyzed carboxylation of the resulting arylaluminum species, which afforded the corresponding carboxylation products in high yield and high selectivity. In addition to benzene derivatives, heteroarenes such as benzofuran, benzothiophene, and indole derivatives are also suitable substrates. Functional groups such as Cl, Br, I, vinyl, amide, and CN could survive the reaction conditions. Some key reaction intermediates such as the copper aryl and isobutyl complexes and their carboxylation products were isolated and structurally characterized by X-ray crystallographic analyses, thus offering important information on the reaction mechanism. PMID:25491488

  9. General approach to the fractionation and class determination of complex mixtures of chlorinated aromatic compounds.

    PubMed

    Albro, P W; Parker, C E

    1980-09-19

    Among the "inadvertent" environmental pollutants are polychlorinated biphenyls, terphenyls, quadphenyls, naphthalenes, diphenyl ethers, dibenzofurans, dibenzo-p-dioxins and benzenes. Mixtures of these classes of compounds also occur in commercial products such as transformer fluids. To analyze such mixtures, gas chromatography--mass spectrometry may be combined with pre-fractionation on basic and acidic alumina columns and semi-quantitative perchlorination techniques. These procedures are illustrated for synthetic mixtures as well as for two samples of stored transformer fluid. Although the described procedure is mainly intended to be applied to the characterization of the major class components of such mixtures, it is also applicable to the determination of trace components such as the dibenzofurans in commercial polychlorinated biphenyls. The mass spectral techniques permit the simultaneous patterning, or "fingerprinting", of the compounds comprising each major class of chlorinated aromatics present. PMID:7451593

  10. Photoinduced Directional and Bidirectional Phase Transitions in Bistable Linear Polycyclic Aromatic Compounds

    NASA Astrophysics Data System (ADS)

    Zhang, Longlong; Yamamoto, Shoji

    2014-06-01

    We study photoinduced phase transitions in linear homocyclic and heterocyclic aromatic polymers, numerically solving the time-dependent Schrödinger equation and observing the photoinduced optical conductivity spectra along the way. All the polycyclic compounds of our interest have bistable cis-trans isomers, which are degenerate in energetics but distinct in optics, and therefore exhibit corresponding photochromism. We reveal that the molecular symmetry is decisive of the photoexchangeability of these bistable configurations, which is directional in molecules of the D2h geometry such as polyacene and paracyanogen but is bidirectional in those of the C2v geometry such as polypyridinopyridine and B, N-substituted acenes. We propose a series of polycyclic compounds for designing tunable photochromism of geometric origin.

  11. Sorption of polar and nonpolar aromatic compounds to two humic acids with varied structural heterogeneity

    SciTech Connect

    Sun, H.Y.; Zhu, D.Q.; Mao, J.D.

    2008-12-15

    The major objective of the present study was to evaluate the correlation between structural nature of humic acids (HAs) and sorption affinity of organic compounds with varied polarity. We compared the sorption behavior of three aromatic compounds-nonpolar phenanthrene (PHEN) and 1,2,4,5-tetrachlorobenzene (TeCB) and highly polar 2,4-dichlorophenol (DCP)-to a solid-phase coal humic acid (CHA) and a soil humic acid (SHA) suspended in aqueous solution. The structural nature of HAs was characterized using elemental analysis, ultraviolet absorbance, diffusive reflectance Fourier-transform infrared, and solid-state C-13 nuclear magnetic resonance. The two tested HAs have very different structural properties: CHA consists primarily of poly(methylene)-rich aliphatics with high aromatic content and some COO/N-C=O but low polarity, while SHA consists of young materials of lignin, carbohydrates, and peptides with high polarity. In response to the structural heterogeneity of HAs, sorption of nonpolar and more hydrophobic solutes (PHEN, TeCB) to CHA is much greater than that to SHA because of the predominance of hydrophobic effects; however, disparities in sorption affinity between the two HAs become smaller for polar and less hydrophobic DCP because of the major role played by polar interactions. The influence of pH on the sorption of different solutes to the two HAs was also discussed. The results of the present work highlight the importance of structural heterogeneity of both solutes and HAs in the sorption process.

  12. Two new luminescent Zn(II) compounds constructed from guanazole and aromatic polycarboxylate ligands

    NASA Astrophysics Data System (ADS)

    Zhao, Haixiang; Dong, Yanli; Liu, Haiping

    2016-02-01

    Two new Zn(II) compounds, namely [(CH3)2NH2]2n[Zn3(bpt)2(datrz)2]n (1) and [(CH3)2NH2)]n[Zn2(bptc)(datrz)]n·n(H2O) (2) (H3bpt = biphenyl-3,4‧,5-tricarboxylic acid, H4bptc = biphenyl-3,3‧,5,5‧-tetracarboxylic acid, Hdatrz = 3,5-diamino-1,2,4-triazole), have been obtained by the self-assemble reactions of Zn(NO3)2, 3,5-diamino-1,2,4-triazole, aromatic polycarboxylate ligands under solvothermal conditions. Single crystal X-ray structural analyses reveal that both compounds display three-dimensional (3D) frameworks. Compound 1 features a trinodal (3, 4, 6)-connected topological network with the point symbol of {4.62}2{4.64.8}{46.64.85}. Compound 2 displays a binodal (4, 6)-connected topological network with the point symbol of {32.62.72}{34.42.64.75}. In addition, the thermal stabilities and luminescent properties of compounds 1 and 2 were also investigated in the solid state at room temperature.

  13. Detection of Nitro aromatics via fluorescence quenching of pegylated and siloxanated 4, 8-dimethylcoumarins

    NASA Astrophysics Data System (ADS)

    Kumar, Abhishek; Pandey, Mukesh; Kumar, Jayant

    2011-03-01

    There is considerable interest in developing chemical sensors for detection of trace explosives. Optical sensors, which rely on the change in optical properties of the material, proved to be very effective. Therefore, there is a need to develop materials for optical sensors which can interact specifically with analytes and detect them sensitively. Here, we report the synthesis of co-polymers of 4, 8-dimethylcoumarins with poly (ethylene glycol) (PEG) and polydimethylsiloxane (PDMS) using Candida Antarctica lipase as a catalyst under solvent-less condition. The low Tg of PEG and PDMS may facilitate porous structure in solid films which allows quencher molecules to easily diffuse in and out of these films. In addition, the co-polymers prevent aggregation and lend themselves easily for thin film fabrication which otherwise is difficult because of low molecular weight of coumarin. Fluorescence quenching of these co-polymer in presence of nitro aromatics, 2,4-dinitrotoulne and 2,4,6-trinitrotoluene, in solution and in vapor phase will be reported. National Science Foundation.

  14. Theoretical modeling of the infrared fluorescence from interstellar polycyclic aromatic hydrocarbons

    NASA Technical Reports Server (NTRS)

    Schutte, W. A.; Tielens, A. G. G. M.; Allamandola, L. J.

    1993-01-01

    We have modeled the family of interstellar IR emission bands at 3.3, 6.2, 7.7, 8.6, 11.3, and 12.7 microns by calculating the fluorescence from a size distribution of interstellar polycyclic aromatic hydrocarbons (PAHs) embedded in the radiation field of a hot star. It is found that the various emission bands are dominated by distinctly different PAHs, from molecules with much less than about 80 C atoms for the 3.3 micron feature, to molecules with 10 exp 2-10 exp 5 C atoms for the emission in the IRAS 12 and 25 micron bands. We quantitatively describe the influence on the emergent spectrum of various PAH properties such as the molecular structure, the amount of dehydrogenation, the intrinsic strength of the IR active modes, and the size distribution. Comparing our model results to the emission spectrum from the Orion Bar region, we conclude that interstellar PAHs are likely fully, or almost fully, hydrogenated. Moreover, it is found that the intrinsic strengths of the 6.2 and 7.7 micron C-C stretching modes, and the 8.6 micron C-H in-plane bending mode are 2-6 times larger than measured for neutral PAHs in the laboratory.

  15. A systematic study of fluorescence-based detection of nitroexplosives and other aromatics in the vapor phase by microporous metal-organic frameworks.

    PubMed

    Pramanik, Sanhita; Hu, Zhichao; Zhang, Xiao; Zheng, Chong; Kelly, Sean; Li, Jing

    2013-11-18

    A systematic study is conducted on four microporous metal-organic framework compounds built on similar ligands but different structures, namely [Zn3(bpdc)3(bpy)]·4DMF·H2O (1), [Zn3(bpdc)3(2,2'dmbpy)]·4DMF·H2O (2), [Zn2(bpdc)2(bpe)]·2DMF (3), and [Zn(bpdc)(bpe)]·DMF (4) (bpdc=4,4'-biphenyldicarboxylate; bpy=4,4'-bipyridine; 2,2'dmbpy=2,2'-dimethyl-4,4'bipyridine; bpe=1,2-bis(4-pyridyl)ethane; DMF=N,N'-dimethylformamide) to investigate their photoluminescence properties and sensing/detection behavior upon exposure to vapors of various aromatic molecules (analytes) including nitroaromatic explosives. The results show that all four compounds are capable of detecting these molecules in the vapor phase through fluorescence quenching or enhancement. Both electrochemical measurements and theoretical calculations are performed to analyze the analyte-MOF interactions, to explain the difference in signal response by different analytes, and to understand the mechanism of fluorescence quenching or enhancement observed in these systems. Interestingly, compound 3 also shows an emission frequency shift when exposed to benzene (BZ), chlorobenzene (ClBZ), and toluene (TO), which provides an additional variable for the identification of different analytes in the same category. PMID:24123511

  16. Laser Induced Fluorescence Spectroscopy of Neutral and Ionized Polycyclic Aromatic Hydrocarbons in a Cosmic Simulation Chamber

    NASA Astrophysics Data System (ADS)

    Bejaoui, Salma; Salama, Farid

    2015-08-01

    Polycyclic aromatic hydrocarbon (PAH) molecules are considered the best carriers to account for the ubiquitous infrared emission bands. PAHs have also been proposed as candidates to explain the diffuse interstellar bands (DIBs), a series of absorption features seen on the interstellar extinction curve and are plausible carriers for the extended red emission (ERE), a photoluminescent process associated with a wide variety of interstellar environments. Extensive efforts have been devoted over the past two decades to characterize the physical and chemical properties of PAH molecules and ions in space. Absorption spectra of PAH molecules and ions trapped in solid matrices have been compared to the DIBs [1, 2]. Absorption spectra of several cold, isolated gas-phase PAHs have also been measured under experimental conditions that mimic the interstellar conditions [see 3 for a review]. The purpose of this study is to provide a new dimension to the existing spectroscopic database of neutral and single ionized PAHs that is largely based on absorption spectra by adding emission spectroscopy data. The measurements are based on the laser-induced fluorescence (LIF) technique [4] and are performed with the Pulsed Discharge Nozzle (PDN) of the COSmIC laboratory facility at NASA Ames laboratory. The PDN generates plasma in a free supersonic jet expansion to simulate the physical and the chemical conditions in interstellar environments. We focus, here, on the fluorescence spectra of large neutral PAHs and their cations where there is a lack of fluorescence spectroscopy data. The astronomical implications of the data (e.g., ERE) are examinedReferences[1] F. Salama, E. Bakes, L.J. Allamandola, A.G.G.M. Tielens, Astrophys. J., 458 (1996) p.621[2] F. Salama, The ISO Revolution, EDP Sciences, Les Ulis, France (1999) p.65[3] Salama F., In Organic Matter in Space, IAU Symposium 251, Kwok & Sandford Eds.Cambridge University Press,4, S251,(2008), p. 357 (2008) and references therein.[4

  17. Evaluation of sampling and analytical methodology for polynuclear aromatic compounds in indoor air. Final report, 1 March-30 September 1985

    SciTech Connect

    Chuang, C.C.; Mack, G.A.; Mondron, P.J.; Petersen, B.A.

    1985-10-01

    The objective of this project was to develop a generic sampling and analytical methodology to characterize the polynuclear aromatic hydrocarbon (PAH) concentrations in air within various microenvironments. The following three studies were performed: evaluation of analytical methods, design of a sampling method, and design of a pilot study. Two analytical methods, high performance liquid chromatography with ultraviolet adsorption and fluorescence detection and gas chromatography/mass spectrometry, were evaluated for the determination of PAHs and their derivatives in air within microenvironments. The results showed that gas chromatography/positive chemical ionization massspectrometry with data acquisition in the selected ion-monitoring mode is the preferred analytical approach. A modified EPA high-volume sampler, consisting of a quartz fiber filter and a polyurethane foam cartridge, is proposed for use in a future experimental study. A literature review was conducted to determine what is known about the contribution of cigarette smoke to the levels of PAHs in air within microenvironments and to evaluate the use of quinoline and isoquinoline as possible marker compounds for the levels of cigarette smoke. A pilot study was designed to assess PAH levels in air found in residences. A study using this design, was conducted in Columbus, Ohio, during the winter of 1983/84. These results can then be applied to a future large-scale study involving the measurement of human exposure to PAH in air.

  18. Selenium status in workers handling aromatic nitro-amino compounds in a chemical factory

    SciTech Connect

    Yoshida, M.; Sunaga, M.; Hara, I. )

    1990-09-01

    The selenium status of workers handling aromatic nitro-amino (ANA) compounds was evaluated by measurement of their blood and urinary selenium concentrations and blood glutathione peroxidase (GSH-Px) activities. Forty-seven healthy Japanese male workers (42.7 +/- 12.1 yr) handling ANA compounds routinely in a chemical factory were studied as exposed workers, and 107 nonindustrial healthy Japanese males (39.3 +/- 10.0 yr) in the same region served as a control group. Urinary diazoreaction-positive metabolites and methemoglobin, both of which have been used as indices of exposure to ANA compounds, were significantly elevated in the exposed workers. Both plasma and erythrocyte selenium in the exposed workers showed 20% lower values compared to the control group. GSH-Px activities in plasma and erythrocytes were also significantly decreased in the exposed workers, but urinary selenium excretions were similar between the two groups. Questionnaire information obtained from each subject regarding intake habits of selenium-rich foods (bread, eggs, meat, and fish) indicated that the average dietary selenium intake was similar for the control group and the exposed workers. These results indicate that (1) the workers handling ANA compounds were surely exposed to these chemicals; (2) their selenium status was lower than that of the nonindustrial controls; and (3) the low selenium status was not associated with any dietary factor.

  19. Ambient cure polyimide foams prepared from aromatic polyisocyanates, aromatic polycarboxylic compounds, furfuryl alcohol, and a strong inorganic acid

    NASA Technical Reports Server (NTRS)

    Sawko, Paul M. (Inventor); Riccitiello, Salvatore R. (Inventor); Hamermesh, Charles L. (Inventor)

    1980-01-01

    Flame and temperature resistant polyimide foams are prepared by the reaction of an aromatic dianhydride, e.g., pyromellitic dianhydride, with an aromatic polyisocyanate, e.g., polymethylene polyphenylisocyanate (PAPI) in the presence of an inorganic acid and a lower molecular weight alcohol, e.g., dilute sulfuric acid or phosphoric acid and furfuryl alcohol. The exothermic reaction between the acid and the alcohol provides the heat necessary for the other reactants to polymerize without the application of any external heat. Such mixtures, therefore, are ideally suited for in situ foam formation, especially where the application of heat is not practical or possible.

  20. The Effects of Molecular Properties on Ready Biodegradation of Aromatic Compounds in the OECD 301B CO2 Evolution Test.

    PubMed

    He, Mei; Mei, Cheng-Fang; Sun, Guo-Ping; Li, Hai-Bei; Liu, Lei; Xu, Mei-Ying

    2016-07-01

    Ready biodegradation is the primary biodegradability of a compound, which is used for discriminating whether a compound could be rapidly and readily biodegraded in the natural ecosystems in a short period and has been applied extensively in the environmental risk assessment of many chemicals. In this study, the effects of 24 molecular properties (including 2 physicochemical parameters, 10 geometrical parameters, 6 topological parameters, and 6 electronic parameters) on the ready biodegradation of 24 kinds of synthetic aromatic compounds were investigated using the OECD 301B CO2 Evolution test. The relationship between molecular properties and ready biodegradation of these aromatic compounds varied with molecular properties. A significant inverse correlation was found for the topological parameter TD, five geometrical parameters (Rad, CAA, CMA, CSEV, and N c), and the physicochemical parameter K ow, and a positive correlation for two topological parameters TC and TVC, whereas no significant correlation was observed for any of the electronic parameters. Based on the correlations between molecular properties and ready biodegradation of these aromatic compounds, the importance of molecular properties was demonstrated as follows: geometrical properties > topological properties > physicochemical properties > electronic properties. Our study first demonstrated the effects of molecular properties on ready biodegradation by a number of experiment data under the same experimental conditions, which should be taken into account to better guide the ready biodegradation tests and understand the mechanisms of the ready biodegradation of aromatic compounds. PMID:26498763

  1. Visual Recognition of Aliphatic and Aromatic Amines Using a Fluorescent Gel: Application of a Sonication-Triggered Organogel.

    PubMed

    Pang, Xuelei; Yu, Xudong; Lan, Haichuang; Ge, Xiaoting; Li, Yajuan; Zhen, Xiaoli; Yi, Tao

    2015-06-24

    A naphthalimide-based fluorescent gelator (N1) containing an alkenyl group has been designed and characterized. This material is able to gelate alcohols via a precipitate-to-gel transformation when triggered with ultrasound for less than 2 min (S-gel). The gelation process in n-propanol was studied by means of absorption, fluorescence, and IR spectra, scanning electron microscopy (SEM) images, and X-ray diffraction patterns. The fluorescence intensity of N1 decreased during the gelation process in a linear relationship with the sonication time. The S-gel of N1 could be used to sense aliphatic and aromatic amines by measuring the change in the signal output. For example, the addition of propylamine to the S-gel of N1 resulted in a dramatic enhancement of the fluorescence intensity, accompanied by a gel-to-sol transition. On the contrary, when the S-gel of N1 was treated with aromatic amines such as aniline, fluorescence was quenched and there was no gel collapse. The sensing mechanisms were studied by (1)H NMR, small-angle X-ray scattering, SEM and spectroscopic experiments. It is proposed that isomerization of the alkenyl group of N1 from the trans to cis form occurs when the S-gel is treated with propylamine, resulting in a gel-sol transition. However, the aromatic aniline molecules prefer to insert into the gel networks of N1 via hydrogen-bonding and charge-transfer interactions, maintaining the gel state. As potential applications, testing strips of N1 were prepared to detect aniline. PMID:26040296

  2. FLUORESCENCE DETECTION AND IDENTIFICATION OF NITRO DERIVATIVES OF POLYNUCLEAR AROMATIC HYDROCARBONS BY ON-COLUMN CATALYTIC REDUCTION TO AROMATIC AMINES

    EPA Science Inventory

    Nitro-PAHs at trace level concentrations were reduced on-column to corresponding amino PAHs with a platinum/rhodium catalyst in a methanol-water reverse-phase HPLC system. The technique provides a convenient and sensitive method for detecting nitro-PAHs by fluorescence measuremen...

  3. How Aromatic Compounds Block DNA Binding of HcaR Catabolite Regulator.

    PubMed

    Kim, Youngchang; Joachimiak, Grazyna; Bigelow, Lance; Babnigg, Gyorgy; Joachimiak, Andrzej

    2016-06-17

    Bacterial catabolism of aromatic compounds from various sources including phenylpropanoids and flavonoids that are abundant in soil plays an important role in the recycling of carbon in the ecosystem. We have determined the crystal structures of apo-HcaR from Acinetobacter sp. ADP1, a MarR/SlyA transcription factor, in complexes with hydroxycinnamates and a specific DNA operator. The protein regulates the expression of the hca catabolic operon in Acinetobacter and related bacterial strains, allowing utilization of hydroxycinnamates as sole sources of carbon. HcaR binds multiple ligands, and as a result the transcription of genes encoding several catabolic enzymes is increased. The 1.9-2.4 Å resolution structures presented here explain how HcaR recognizes four ligands (ferulate, 3,4-dihydroxybenzoate, p-coumarate, and vanillin) using the same binding site. The ligand promiscuity appears to be an adaptation to match a broad specificity of hydroxycinnamate catabolic enzymes while responding to toxic thioester intermediates. Structures of apo-HcaR and in complex with a specific DNA hca operator when combined with binding studies of hydroxycinnamates show how aromatic ligands render HcaR unproductive in recognizing a specific DNA target. The current study contributes to a better understanding of the hca catabolic operon regulation mechanism by the transcription factor HcaR. PMID:27129205

  4. Enhanced Photoreduction of Nitro-aromatic Compounds by Hydrated Electrons Derived from Indole on Natural Montmorillonite.

    PubMed

    Tian, Haoting; Guo, Yong; Pan, Bo; Gu, Cheng; Li, Hui; Boyd, Stephen A

    2015-07-01

    A new photoreduction pathway for nitro-aromatic compounds (NACs) and the underlying degradation mechanism are described. 1,3-Dinitrobenzene was reduced to 3-nitroaniline by the widely distributed aromatic molecule indole; the reaction is facilitated by montmorillonite clay mineral under both simulated and natural sunlight irradiation. The novel chemical reaction is strongly affected by the type of exchangeable cation present on montmorillonite. The photoreduction reaction is initiated by the adsorption of 1,3-dinitrobenzene and indole in clay interlayers. Under light irradiation, the excited indole molecule generates a hydrated electron and the indole radical cation. The structural negative charge of montmorillonite plausibly stabilizes the radical cation hence preventing charge recombination. This promotes the release of reactive hydrated electrons for further reductive reactions. Similar results were observed for the photoreduction of nitrobenzene. In situ irradiation time-resolved electron paramagnetic resonance and Fourier transform infrared spectroscopies provided direct evidence for the generation of hydrated electrons and the indole radical cations, which supported the proposed degradation mechanism. In the photoreduction process, the role of clay mineral is to both enhance the generation of hydrated electrons and to provide a constrained reaction environment in the galley regions, which increases the probability of contact between NACs and hydrated electrons. PMID:26029791

  5. Prenylation of aromatic compounds, a key diversification of plant secondary metabolites.

    PubMed

    Yazaki, Kazufumi; Sasaki, Kanako; Tsurumaru, Yusuke

    2009-01-01

    Prenylation plays a major role in the diversification of aromatic natural products, such as phenylpropanoids, flavonoids, and coumarins. This biosynthetic reaction represents the crucial coupling process of the shikimate or polyketide pathway providing an aromatic moiety and the isoprenoid pathway derived from the mevalonate or methyl erythritol phosphate (MEP) pathway, which provides the prenyl (isoprenoid) chain. In particular, prenylation contributes strongly to the diversification of flavonoids, due to differences in the prenylation position on the aromatic rings, various lengths of prenyl chain, and further modifications of the prenyl moiety, e.g., cyclization and hydroxylation, resulting in the occurrence of ca. 1000 prenylated flavonoids in plants. Many prenylated flavonoids have been identified as active components in medicinal plants with biological activities, such as anti-cancer, anti-androgen, anti-leishmania, and anti-nitric oxide production. Due to their beneficial effects on human health, prenylated flavonoids are of particular interest as lead compounds for producing drugs and functional foods. However, the gene coding for prenyltransferases that catalyze the key step of flavonoid prenylation have remained unidentified for more than three decades, because of the membrane-bound nature of these enzymes. Recently, we have succeeded in identifying the first prenyltransferase gene SfN8DT-1 from Sophora flavescens, which is responsible for the prenylation of the flavonoid naringenin at the 8-position, and is specific for flavanones and dimethylallyl diphosphate (DMAPP) as substrates. Phylogenetic analysis showed that SfN8DT-1 has the same evolutionary origin as prenyltransferases for vitamin E and plastoquinone. A prenyltransferase GmG4DT from soybean, which is involved in the formation of glyceollin, was also identified recently. This enzyme was specific for pterocarpan as its aromatic substrate, and (-)-glycinol was the native substrate yielding the

  6. Migration kinetics of primary aromatic amines from polyamide kitchenware: Easy and fast screening procedure using fluorescence.

    PubMed

    Sanllorente, S; Sarabia, L A; Ortiz, M C

    2016-11-01

    Primary aromatic amines, PAAs, and their derivatives constitute a health risk and control of their migration from food contact materials is the subject of permanent attention by the authorities. 25.1% of notifications made by Rapid Alert System for Food and Feed in the European Union between 2010 and 2015 concerned PAAs, polyamide cooking utensils being a common source. It is thus useful to have fast and efficient analytical methods for their control. In this work a non-separative, easy, fast and inexpensive spectrofluorimetric method based on the second order calibration of excitation-emission fluorescence matrices (EEMs) was proposed for the determination of aniline (ANL), 2,4-diaminotoluene (2,4-TDA) and 4,4'-methylenedianiline (4,4'-MDA) in polyamide cooking utensils. The procedure made it possible to identify unequivocally each analyte. Trilinearity of the data tensor guarantees the uniqueness of the solution obtained through parallel factor analysis (PARAFAC), so the factors of the decomposition match up with the analytes. The three analytes were unequivocally identified by the correlation between the pure spectra and the PARAFAC excitation and emission spectral loadings. The recovery percentages found were, 82.6%, 112.7% and 84.4% for ANL, 2,4-TDA and 4,4'-MDA respectively. The proposed method was applied to carry out a migration test from polyamide cooking utensils, using a 3% (w/v) acetic acid in aqueous solution as food simulant. Detectable levels of 4,4'-MDA were found in food simulant from some of the investigated cooking utensils. Finally, a kinetic model for the migration of 4,4'-MDA has been fitted to experimental data obtained in the migration test. Thanks to the selectivity of PARAFAC calibration, which greatly simplifies sample treatment avoiding the use of toxic solvents, the developed method follows most green analytical chemistry principles. PMID:27591586

  7. A novel sensing mechanism for optic detection of aromatic compounds including chlorophenols

    SciTech Connect

    Zhao, Shishan; Luong, J.H.T.

    1995-12-01

    Development of chemosensors and new sensing mechanisms is encouraging for the detection of environmentally and biologically important species. This paper presents a novel design of optic chemosensors for small aromatic compounds including chlorophenols, which represent a large part of the organic pollutants. Cap-shaped assemblies are prepared from the torus-shaped cyclodextrins (CyDs) and planar porphyrin (POR). The assemblies exhibit an intensive absorption maximum at 420.5 nm and is sensitive to the inclusion of guest molecules. For highly selective recognition of an analyte, the necessary condition is the affinity of its hydrophobic benzene ring to the CyD cavity and the sufficient condition is the interaction between its hydrogen-bonding functional group(s) and the porphyrin cycle.

  8. Screening of halogenated aromatic compounds in some raw material lots for an aluminium recycling plant.

    PubMed

    Sinkkonen, Seija; Paasivirta, Jaakko; Lahtiperä, Mirja; Vattulainen, Antero

    2004-05-01

    Four samples of scrap raw materials for an aluminium recycling plant were screened for the occurrence of persistent halogenated aromatic compounds. The samples contained waste from handling of electric and electronic plastics, filter dust from electronic crusher, cyclone dust from electronic crusher and light fluff from car shredder. In our screening analyses, brominated flame retardants were observed in all samples. Polybrominated diphenyl ethers (PBDE) were identified in all samples in amounts of 245-67450 ng/g. The major PBDE congeners found were decabromo- and pentabromodiphenyl ethers. 1,1-bis(2,4,6-tribromophenoxy)ethane, hexabromobenzene, ethyl-pentabromobenzene, tetrabromobisphenol-A, pentabromotoluene and dimethyl tetrabromobenzene were observed in all scrap samples. The concentrations of PCBs, PCNs (polychlorinated naphthalenes) and nona- to undecachlorinated terphenyls in some of these scrap samples were remarkably high. PMID:14987867

  9. Determining inhibition effects of some aromatic compounds on peroxidase enzyme purified from white and red cabbage

    NASA Astrophysics Data System (ADS)

    Öztekin, Aykut; Almaz, Züleyha; Özdemir, Hasan

    2016-04-01

    Peroxidases (E.C.1.11.1.7) catalyze the one electron oxidation of wide range of substrates. They are used in synthesis reaction, removal of peroxide from industrial wastes, clinical biochemistry and immunoassays. In this study, the white cabbage (Brassica Oleracea var. capitata f. alba) and red cabbage (Brassica oleracea L. var. capitata f. rubra) peroxidase enzymes were purified for investigation of inhibitory effect of some aromatic compounds on these enzymes. IC50 values and Ki constants were calculated for the molecules of 6-Amino nicotinic hydrazide, 6-Amino-5-bromo nicotinic hydrazide, 2-Amino-5-hydroxy benzohydrazide, 4-Amino-3-hydroxy benzohydrazide on purified enzymes and inhibition type of these molecules were determined. (This research was supported by Ataturk University. Project Number: BAP-2015/98).

  10. Evaluation of aromatic plants and compounds used to fight multidrug resistant infections.

    PubMed

    Perumal Samy, Ramar; Manikandan, Jayapal; Al Qahtani, Mohammed

    2013-01-01

    Traditional medicine plays a vital role for primary health care in India, where it is widely practiced to treat various ailments. Among those obtained from the healers, 78 medicinal plants were scientifically evaluated for antibacterial activity. Methanol extract of plants (100  μ g of residue) was tested against the multidrug resistant (MDR) Gram-negative and Gram-positive bacteria. Forty-seven plants showed strong activity against Burkholderia pseudomallei (strain TES and KHW) and Staphylococcus aureus, of which Tragia involucrata L., Citrus acida Roxb. Hook.f., and Aegle marmelos (L.) Correa ex Roxb. showed powerful inhibition of bacteria. Eighteen plants displayed only a moderate effect, while six plants failed to provide any evidence of inhibition against the tested bacteria. Purified compounds showed higher antimicrobial activity than crude extracts. The compounds showed less toxic effect to the human skin fibroblasts (HEPK) cells than their corresponding aromatic fractions. Phytochemical screening indicates that the presence of various secondary metabolites may be responsible for this activity. Most of the plant extracts contained high levels of phenolic or polyphenolic compounds and exhibited activity against MDR pathogens. In conclusion, plants are promising agents that deserve further exploration. Lead molecules available from such extracts may serve as potential antimicrobial agents for future drug development to combat diseases caused by the MDR bacterial strains as reported in this study. PMID:24223059

  11. Evaluation of Aromatic Plants and Compounds Used to Fight Multidrug Resistant Infections

    PubMed Central

    Perumal Samy, Ramar; Manikandan, Jayapal; Al Qahtani, Mohammed

    2013-01-01

    Traditional medicine plays a vital role for primary health care in India, where it is widely practiced to treat various ailments. Among those obtained from the healers, 78 medicinal plants were scientifically evaluated for antibacterial activity. Methanol extract of plants (100 μg of residue) was tested against the multidrug resistant (MDR) Gram-negative and Gram-positive bacteria. Forty-seven plants showed strong activity against Burkholderia pseudomallei (strain TES and KHW) and Staphylococcus aureus, of which Tragia involucrata L., Citrus acida Roxb. Hook.f., and Aegle marmelos (L.) Correa ex Roxb. showed powerful inhibition of bacteria. Eighteen plants displayed only a moderate effect, while six plants failed to provide any evidence of inhibition against the tested bacteria. Purified compounds showed higher antimicrobial activity than crude extracts. The compounds showed less toxic effect to the human skin fibroblasts (HEPK) cells than their corresponding aromatic fractions. Phytochemical screening indicates that the presence of various secondary metabolites may be responsible for this activity. Most of the plant extracts contained high levels of phenolic or polyphenolic compounds and exhibited activity against MDR pathogens. In conclusion, plants are promising agents that deserve further exploration. Lead molecules available from such extracts may serve as potential antimicrobial agents for future drug development to combat diseases caused by the MDR bacterial strains as reported in this study. PMID:24223059

  12. My favorite aromatic compounds--a tribute to friedrich August Kekulé.

    PubMed

    Hopf, Henning

    2014-10-01

    [For a discussion of this picture, please see the Editor's postscript at the end of the paper] Note from the Editor: We are all collectors. All one needs to do is explore a flea market, an antique fair or especially a weekend street market to understand the range of human collections. Tetsuo Nozoe, whom this project celebrates, collected autographs as well as the friendship of those who signed his books! What we collect doesn't necessarily have to be tangible. We all collect memories, stories, and anecdotes. We chemists are particularly privileged: we also collect molecules and reactions. In the essay that follows, Professor Henning Hopf shares with us his collection of favorite aromatic compounds. Hopf is the perfect chemist to have undertaken this sharing, for he has been active in the field of novel aromatic compounds for over four decades. Furthermore, Hopf is a deeply philosophical scientist. I very much admire his 2008 paper with Roald Hoffmann, "Learning from Molecules in Distress" published in Angewandte Chemie, a journal from the same pubilshers as The Chemical Record. As you read the paper that follows, imagine that Professor Hopf has just welcomed you to his home and is giving you a tour of his artwork. The walls are covered with works of Boekelheide, Cram, Fittig, Hückel, Kuck, Müllen, Newman, Scott, and Willstätter among others. Oh, yes, there's a Hopf or two! Enjoy your time in this very special museum. -Jeffrey I. Seeman Guest Editor University of Richmond Richmond, Virginia 23173, USA E-mail: jseeman@richmond.edu. PMID:25205433

  13. Low-pressure effective fluorescence lifetimes and photo-physical rate constants of one- and two-ring aromatics

    NASA Astrophysics Data System (ADS)

    Benzler, Thorsten; Faust, Stephan; Dreier, Thomas; Schulz, Christof

    2015-12-01

    One- and two-ring aromatics such as toluene and naphthalene are frequently used molecular tracer species in laser-induced fluorescence (LIF) imaging diagnostics. Quantifying LIF signal intensities requires knowledge of the photo-physical processes that determine the fluorescence quantum yield. Collision-induced and intramolecular energy transfer processes in the excited electronic state closely interact under practical conditions. They can be separated through experiments at variable low pressures. Effective fluorescence lifetimes of gaseous toluene, 1,2,4-trimethylbenzene, anisole, naphthalene, and 1-methylnaphthalene diluted in CO2 were measured after picosecond laser excitation at 266 nm and time-resolved detection of fluorescence intensities. Measurements in an optically accessible externally heated cell between 296 and 475 K and 0.010-1 bar showed that effective fluorescence lifetimes generally decrease with temperature, while the influence of the bath-gas pressure depends on the respective target species and temperature. The results provide non-radiative and fluorescence rate constants and experimentally validate the effect of photo-induced cooling.

  14. BIODEGRADATION OF AROMATIC COMPOUNDS UNDER MIXED OXYGEN/DENITRIFYING CONDITIONS: A REVIEW

    EPA Science Inventory

    Bioremediation of aromatic hydrocarbons in groundwater and sediments is often limited by dissolved oxygen. Many aromatic hydrocarbons degrade very slowly or not at all under anaerobic conditions. Nitrate is a good alternative electron acceptor to oxygen, and denitrifying bacteria...

  15. Ozone-related fluorescent compounds in mouse liver and lung

    SciTech Connect

    Csallany, A.S.; Manwaring, J.D.; Menken, B.Z.

    1985-08-01

    Groups of ten female, weanling mice were fed a basal, vitamin E-deficient diet or a basal diet supplemented with RRR-alpha-tocopheryl acetate for 14 months. During the last month one group from each dietary regimen was exposed for 30-60 min/day to 1.5 ppm ozone (25 hr total ozone exposure) and the remaining groups to control ambient air. The liver and lung tissues were homogenized and extracted with 2:1 chloroform:methanol and water. Excitation and emission wavelengths for the eluting fractions were determined by continuous emission scans from 250 to 600 nm for each excitation wavelength between 250 and 500 nm. Ozone exposure did not effect the concentration of any of the fluorescent materials examined in the lung, but it resulted in a significant increase in two of four water-soluble compounds in the liver with excitation wavelength maxima/emission wavelength maxima of 270 nm/310 nm and 275 nm/350 nm (smaller molecular weight material) suggesting in vivo lipid oxidation.

  16. GaN-nanowire/ TiO2-nanocluster hybrid sensors for detection of Benzene and related aromatic compounds

    NASA Astrophysics Data System (ADS)

    Aluri, Geetha S.; Motayed, Abhishek; Davydov, Albert V.; Oleshko, Vladimir; Bertness, Kris A.; Sanford, Norman A.; Rao, Mulpuri V.

    2011-05-01

    Nanowire-nanocluster hybrid chemical sensors were realized by functionalizing gallium nitride (GaN) nanowires with titanium dioxide (TiO2) nanoclusters for selectively sensing Benzene and other related aromatic compounds. Hybrid sensor devices were developed by fabricating two-terminal devices using individual GaN nanowires followed by the deposition of TiO2 nanoclusters using RF magnetron sputtering. The sensor fabrication process employed all standard micro-fabrication techniques. A change of current was observed for these hybrid sensors when exposed to aromatic compounds such as Benzene, Toluene, Ethylbenzene, Xylene, and Chlorobenzene mixed with air. However, these sensors did not show any sensitivity when exposed to Methanol, Ethanol, Isopropanol, Chloroform, Acetone, and 1, 3-Hexadiene. These sensors were capable of sensing the aromatic compounds only under ultraviolet excitation. The sensitivity range for the above mentioned aromatic compounds varied from 1% down to 50 parts per billion (ppb) at room-temperature. By combining the enhanced catalytic properties of the TiO2 nanoclusters with the sensitive transduction capability of the nanowires, an ultra-sensitive and highly selective chemical sensing architecture is demonstrated. We have proposed a mechanism that could qualitatively explain the observed sensing behavior.

  17. Aqueous and Tissue Residue-Based Interspecies Correlation Estimation Models Provide Conservative Hazard Estimates for Aromatic Compounds

    EPA Science Inventory

    Interspecies correlation estimation (ICE) models were developed for 30 nonpolar aromatic compounds to allow comparison of prediction accuracy between 2 data compilation approaches. Type 1 models used data combined across studies, and type 2 models used data combined only within s...

  18. Importance of heterocylic aromatic compounds in monitored natural attenuation for coal tar contaminated aquifers: A review.

    PubMed

    Blum, Philipp; Sagner, Anne; Tiehm, Andreas; Martus, Peter; Wendel, Thomas; Grathwohl, Peter

    2011-11-01

    NSO heterocycles (HET) are typical constituents of coal tars. However, HET are not yet routinely monitored, although HET are relatively toxic coal tar constituents. The main objectives of the study is therefore to review previous studies and to analyse HET at coal tar polluted sites in order to assess the relevance of HET as part of monitored natural attenuation (MNA) or any other long-term monitoring programme. Hence, natural attenuation of typical HET (indole, quinoline, carbazole, acridine, methylquinolines, thiophene, benzothiophene, dibenzothiophene, benzofuran, dibenzofuran, methylbenzofurans, dimethylbenzofurans and xanthene) were studied at three different field sites in Germany. Compound-specific plume lengths were determined for all main contaminant groups (BTEX, PAH and HET). The results show that the observed plume lengths are site-specific and are above 250m, but less than 1000m. The latter, i.e. the upper limit, however mainly depends on the level of investigation, the considered compound, the lowest measured concentration and/or the achieved compound-specific detection limit and therefore cannot be unequivocally defined. All downstream contaminant plumes exhibited HET concentrations above typical PAH concentrations indicating that some HET are generally persistent towards biodegradation compared to other coal tar constituents, which results in comparatively increased field-derived half-lives of HET. Additionally, this study provides a review on physicochemical and toxicological parameters of HET. For three well investigated sites in Germany, the biodegradation of HET is quantified using the centre line method (CLM) for the evaluation of bulk attenuation rate constants. The results of the present and previous studies suggest that implementation of a comprehensive monitoring programme for heterocyclic aromatic compounds is relevant at sites, if MNA is considered in risk assessment and for remediation. PMID:22115084

  19. Compounds having aromatic rings and side-chain amide-functionality and a method for transporting monovalent anions across biological membranes using the same

    DOEpatents

    Davis, Jeffery T.; Sidorov, Vladimir; Kotch, Frank W.

    2008-04-08

    A compound containing at least two aromatic rings covalently bonded together, with each aromatic ring containing at least one oxyacetamide-based side chain, the compound being capable of forming a chloride ion channel across a lipid bilayer, and transporting chloride ion across the lipid bilayer.

  20. Hierarchy of Carbon Source Utilization in Soil Bacteria: Hegemonic Preference for Benzoate in Complex Aromatic Compound Mixtures Degraded by Cupriavidus pinatubonensis Strain JMP134.

    PubMed

    Pérez-Pantoja, Danilo; Leiva-Novoa, Pablo; Donoso, Raúl A; Little, Cedric; Godoy, Margarita; Pieper, Dietmar H; González, Bernardo

    2015-06-15

    Cupriavidus pinatubonensis JMP134, like many other environmental bacteria, uses a range of aromatic compounds as carbon sources. Previous reports have shown a preference for benzoate when this bacterium grows on binary mixtures composed of this aromatic compound and 4-hydroxybenzoate or phenol. However, this observation has not been extended to other aromatic mixtures resembling a more archetypal context. We carried out a systematic study on the substrate preference of C. pinatubonensis JMP134 growing on representative aromatic compounds channeled through different catabolic pathways described in aerobic bacteria. Growth tests of nearly the entire set of binary combinations and in mixtures composed of 5 or 6 aromatic components showed that benzoate and phenol were always the preferred and deferred growth substrates, respectively. This pattern was supported by kinetic analyses that showed shorter times to initiate consumption of benzoate in aromatic compound mixtures. Gene expression analysis by real-time reverse transcription-PCR (RT-PCR) showed that, in all mixtures, the repression by benzoate over other catabolic pathways was exerted mainly at the transcriptional level. Additionally, inhibition of benzoate catabolism suggests that its multiple repressive actions are not mediated by a sole mechanism, as suggested by dissimilar requirements of benzoate degradation for effective repression in different aromatic compound mixtures. The hegemonic preference for benzoate over multiple aromatic carbon sources is not explained on the basis of growth rate and/or biomass yield on each single substrate or by obvious chemical or metabolic properties of these aromatic compounds. PMID:25795675

  1. Hierarchy of Carbon Source Utilization in Soil Bacteria: Hegemonic Preference for Benzoate in Complex Aromatic Compound Mixtures Degraded by Cupriavidus pinatubonensis Strain JMP134

    PubMed Central

    Pérez-Pantoja, Danilo; Leiva-Novoa, Pablo; Donoso, Raúl A.; Little, Cedric; Godoy, Margarita; Pieper, Dietmar H.

    2015-01-01

    Cupriavidus pinatubonensis JMP134, like many other environmental bacteria, uses a range of aromatic compounds as carbon sources. Previous reports have shown a preference for benzoate when this bacterium grows on binary mixtures composed of this aromatic compound and 4-hydroxybenzoate or phenol. However, this observation has not been extended to other aromatic mixtures resembling a more archetypal context. We carried out a systematic study on the substrate preference of C. pinatubonensis JMP134 growing on representative aromatic compounds channeled through different catabolic pathways described in aerobic bacteria. Growth tests of nearly the entire set of binary combinations and in mixtures composed of 5 or 6 aromatic components showed that benzoate and phenol were always the preferred and deferred growth substrates, respectively. This pattern was supported by kinetic analyses that showed shorter times to initiate consumption of benzoate in aromatic compound mixtures. Gene expression analysis by real-time reverse transcription-PCR (RT-PCR) showed that, in all mixtures, the repression by benzoate over other catabolic pathways was exerted mainly at the transcriptional level. Additionally, inhibition of benzoate catabolism suggests that its multiple repressive actions are not mediated by a sole mechanism, as suggested by dissimilar requirements of benzoate degradation for effective repression in different aromatic compound mixtures. The hegemonic preference for benzoate over multiple aromatic carbon sources is not explained on the basis of growth rate and/or biomass yield on each single substrate or by obvious chemical or metabolic properties of these aromatic compounds. PMID:25795675

  2. Transformation of polycyclic aromatic hydrocarbons by laccase is strongly enhanced by phenolic compounds present in soil.

    PubMed

    Cañas, Ana I; Alcalde, Miguel; Plou, Francisco; Martínez, Maria Jesús; Martínez, Angel T; Camarero, Susana

    2007-04-15

    Efficient transformation of several polycyclic aromatic hydrocarbons (PAHs) was obtained using a fungal laccase in the presence of phenolic compounds related to those formed in nature during the turnover of lignin and humus. The effect of these natural mediators, namely vanillin, acetovanillone, acetosyringone, syringaldehyde, 2,4,6-trimethylphenol, p-coumaric acid, ferulic acid, and sinapic acid, was compared with that of synthetic mediators such as 2,2'-azinobis-(3-ethylbenzothiazoline-6-sulfonate) (ABTS) and 1-hydroxybenzotriazole (HBT). Anthracene was significantly degraded by laccase in the absence of mediators, whereas benzo[a]pyrene and pyrene were weakly transformed (less than 15% after 24 h). Vanillin, acetovanillone, 2,4,6-trimethylphenol, and, above all, p-coumaric acid strongly promoted the removal of PAHs by laccase. 9,10-Anthraquinone was the main product detected from anthracene oxidation by all the laccase-mediator systems. The yield of anthraquinone formed was directly correlated with the amount of p-coumaric acid used. This compound resulted in a better laccase mediator than ABTS and close similarity to HBT, attaining 95% removal of anthracene and benzo[a]pyrene and around 50% of pyrene within 24 h. Benzo[a]pyrene 1,6-, 3,6-, and 6,12-quinones were produced during benzo[a]pyrene oxidation with laccase and p-coumaric acid, HBT, or ABTS as mediators, although use of the latter mediator gave further oxidation products that were not produced by the two other systems. PMID:17533865

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

    PubMed

    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. PMID:26178826

  4. Determination of aromatic tracer compounds for environmental tobacco smoke aerosol by two step laser mass spectrometry

    NASA Astrophysics Data System (ADS)

    Morrical, Brad D.; Zenobi, Renato

    Cigarette smoking is a major cause of indoor aerosol pollution. Determination of exposure to environmental tobacco smoke (ETS) aerosol is critical to understanding health effects. Sizing studies have shown that ETS has a size distribution that is efficiently deposited into the lungs and can therefore provide effective delivery of carcinogenic compounds into the human body. Two-step laser mass spectrometry is used to analyze aromatic compounds on aerosols collected from a smoking lobby. The determination and suitability of ETS tracers on aerosols is examined. Additionally, the transport of aerosol from the smoking lobby is examined to determine what effect deposition and dilution have on the mass spectrum observed. Results from the analysis of ETS, both from lobby samples and direct cigarette sampling, show that several unique peaks are present in the mass spectrum when compared to other combustion sources, such as automobiles and diesel trucks. In particular, ions at m/ z 118, 132, 146, and 160 are consistently present and are not found in other combustion sources. For the indoor environment, where chemical transformation is much less rapid than in the outdoor environment, these ions were found to be present as soon as the first smokers appeared and persisted over the course of the day. Aerosol samples taken in the morning prior to the presence of smokers in the lobby reveal the presence of skeletal PAHs, indicative of outdoor urban traffic aerosol penetration into the building.

  5. PcaK, a high-affinity permease for the aromatic compounds 4-hydroxybenzoate and protocatechuate from Pseudomonas putida.

    PubMed Central

    Nichols, N N; Harwood, C S

    1997-01-01

    PcaK is a transporter and chemoreceptor protein from Pseudomonas putida that is encoded as part of the beta-ketoadipate pathway regulon for aromatic acid degradation. When expressed in Escherichia coli, PcaK was localized to the membrane and catalyzed the accumulation of two aromatic substrates, 4-hydroxybenzoate and protocatechuate, against a concentration gradient. Benzoate inhibited 4-hydroxybenzoate uptake but was not a substrate for PcaK-catalyzed transport. A P. putida pcaK mutant was defective in its ability to accumulate micromolar amounts of 4-hydroxybenzoate and protocatechuate. The mutant was also impaired in growth on millimolar concentrations of these aromatic acids. In contrast, the pcaK mutant grew at wild-type rates on benzoate. The Vmax for uptake of 4-hydroxybenzoate was at least 25 nmol/min/mg of protein, and the Km was 6 microM. PcaK-mediated transport is energized by the proton motive force. These results show that although aromatic acids in the undissociated (uncharged) form can diffuse across bacterial membranes, high-specificity active transport systems probably also contribute to the ability of bacteria to grow on the micromolar concentrations of these compounds that are typically present in soil. A variety of aromatic molecules, including naturally occurring lignin derivatives and xenobiotics, are metabolized by bacteria and may be substrates for transport proteins. The characterization of PcaK provides a foundation for understanding active transport as a critical step in the metabolism of aromatic carbon sources. PMID:9260946

  6. Emissions of C6-C8 aromatic compounds in the United States: Constraints from tall tower and aircraft measurements

    NASA Astrophysics Data System (ADS)

    Hu, Lu; Millet, Dylan B.; Baasandorj, Munkhbayar; Griffis, Timothy J.; Travis, Katherine R.; Tessum, Christopher W.; Marshall, Julian D.; Reinhart, Wesley F.; Mikoviny, Tomas; Müller, Markus; Wisthaler, Armin; Graus, Martin; Warneke, Carsten; Gouw, Joost

    2015-01-01

    present two full years of continuous C6-C8 aromatic compound measurements by PTR-MS at the KCMP tall tower (Minnesota, US) and employ GEOS-Chem nested grid simulations in a Bayesian inversion to interpret the data in terms of new constraints on US aromatic emissions. Based on the tall tower data, we find that the RETRO inventory (year-2000) overestimates US C6-C8 aromatic emissions by factors of 2.0-4.5 during 2010-2011, likely due in part to post-2000 reductions. Likewise, our implementation of the US EPA's NEI08 overestimates the toluene flux by threefold, reflecting an inventory bias in non-road emissions plus uncertainties associated with species lumping. Our annual top-down emission estimates for benzene and C8 aromatics agree with the NEI08 bottom-up values, as does the inferred contribution from non-road sources. However, the NEI08 appears to underestimate on-road emissions of these compounds by twofold during the warm season. The implied aromatic sources upwind of North America are more than double the prior estimates, suggesting a substantial underestimate of East Asian emissions, or large increases there since 2000. Long-range transport exerts an important influence on ambient benzene over the US: on average 43% of its wintertime abundance in the US Upper Midwest is due to sources outside North America. Independent aircraft measurements show that the inventory biases found here for C6-C8 aromatics also apply to other parts of the US, with notable exceptions for toluene in California and Houston, Texas. Our best estimates of year-2011 contiguous US emissions are 206 (benzene), 408 (toluene), and 822 (C8 aromatics) GgC.

  7. Bromination of aromatic compounds by residual bromide in sodium chloride matrix modifier salt during heated headspace GC/MS analysis.

    PubMed

    Fine, Dennis D; Ko, Saebom; Huling, Scott

    2013-12-15

    Analytical artifacts attributed to the bromination of toluene, xylenes, and trimethylbenzenes were found during the heated headspace gas chromatography/mass spectrometry (GC/MS) analysis of aqueous samples. The aqueous samples were produced from Fenton-like chemical oxidation reactions and contained aromatic compounds, hydrogen peroxide (H2O2), and ferric sulfate. Prior to GC/MS headspace analysis, the samples were acidified (pH<2), and sodium chloride was amended to the headspace vial as a matrix modifier. The brominated artifacts were generated during heated headspace analysis. Further, when samples were spiked with a mixture of volatile chlorinated and aromatic compounds (50 µg/L), poor spike recoveries of toluene and xylenes occurred, and in some cases complete loss of trimethylbenzenes and naphthalene resulted. Where poor recovery of aromatic spike compounds occurred, brominated aromatic compounds were found. The only significant source of bromine in the reaction scheme is the bromide typically present (<0.01% w/w) in the sodium chloride amended to the samples. Conversely, brominated artifacts were absent when a buffered salt mixture composed of sodium chloride and potassium phosphate dibasic/monobasic was used as a matrix modifier and raised the sample pH (pH~6). This indicated that the brominated artifacts resulted from the reaction of the aromatic compounds with BrCl, which was formed by the reaction of H2O2, chloride, and bromide under acidic conditions. An alternative matrix modifier salt is recommended that prevents the bromination reaction and avoids these deleterious effects on sample integrity during headspace analysis. PMID:24209304

  8. Sources of SOA gaseous precursors in contrasted urban environments: a focus on mono-aromatic compounds and intermediate volatility compounds

    NASA Astrophysics Data System (ADS)

    Salameh, Therese; Borbon, Agnès; Ait-Helal, Warda; Afif, Charbel; Sauvage, Stéphane; Locoge, Nadine; Bonneau, Stéphane; Sanchez, Olivier

    2016-04-01

    Among Volatile Organic Compounds (VOC), the mono-aromatic compounds so-called BTEX (Benzene, Toluene, Ethylbenzene, and Xylenes) and the intermediate volatility organic compounds (IVOC) with C>12 are two remarkable chemical families having high impact on health, as well as on the production of secondary pollutants like secondary organic aerosols (SOA) and ozone. However, the nature and relative importance of their sources and, consequently, their impact on SOA formation at urban scale is still under debate. On the one hand, BTEX observations in urban areas of northern mid-latitudes do not reconcile with emission inventories; the latter pointing to solvent use as the dominant source compared to traffic. Moreover, a recent study by Borbon et al. (2013) has shown an enrichment in the C7-C9 aromatic fraction in Paris atmosphere by a factor of 3 compared to other cities. Causes would be: (i) differences in gasoline composition, (ii) differences in vehicle fleet composition, and (iii) differences in solvent use related sources. On the other hand, many smog chamber studies have highlighted IVOCs as important SOA precursors over the last decade but their origin and importance in urban areas relative to other precursors like BTEX is still poorly addressed. Here we combined large VOC datasets to investigate sources of BTEX and IVOC in contrasted urban areas by source-receptor approaches and laboratory experiments. Ambient data include multi-site speciated ambient measurements of C2 to C17 VOCs (traffic, urban background, and tunnel) from air quality networks (ie. AIRPARIF in Paris) and intensive field campaigns (MEGAPOLI-Paris, TRANSEMED in Beirut and Istanbul, PHOTOPAQ in Brussels). Preliminary results for Paris suggest that traffic dominates BTEX concentrations while traffic and domestic heating for IVOC (>70%). In parallel, the detailed composition of the fuel liquid phase was determined at the laboratory for typical fuels distributed in Ile de France region (diesel, SP95

  9. Chromatography, Absorption, and Fluorescence: A New Instrumental Analysis Experiment on the Measurement of Polycyclic Aromatic Hydrocarbons in Cigarette Smoke

    NASA Astrophysics Data System (ADS)

    Wingen, Lisa M.; Low, Jason C.; Finlayson-Pitts, Barbara J.

    1998-12-01

    The recent approval by the American Chemical Society of an undergraduate chemistry degree with an option in environmental chemistry requires the development of new experiments that teach fundamental chemistry in the context of environmental issues. We present an experiment suitable for an undergraduate junior/senior-level instrumental analysis laboratory which illustrates the principles of high-performance liquid chromatography (HPLC) and its application to the identification and measurement of polycyclic aromatic hydrocarbons (PAH) in tobacco smoke. Absorption and fluorescence detection methods for PAH, especially the differences in sensitivity and selectivity of these methods, are clearly demonstrated along with the basic principles of HPLC.

  10. Trophic transfer of naturally produced brominated aromatic compounds in a Baltic Sea food chain.

    PubMed

    Dahlgren, Elin; Lindqvist, Dennis; Dahlgren, Henrik; Asplund, Lillemor; Lehtilä, Kari

    2016-02-01

    Brominated aromatic compounds (BACs) are widely distributed in the marine environment. Some of these compounds are highly toxic, such as certain hydroxylated polybrominated diphenyl ethers (OH-PBDEs). In addition to anthropogenic emissions through use of BACs as e.g. flame retardants, BACs are natural products formed by marine organisms such as algae, sponges, and cyanobacteria. Little is known of the transfer of BACs from natural producers and further up in the trophic food chain. In this study it was observed that total sum of methoxylated polybrominated diphenyl ethers (MeO-PBDEs) and OH-PBDEs increased in concentration from the filamentous red alga Ceramium tenuicorne, via Gammarus sp. and three-spined stickleback (Gasterosteus aculeatus) to perch (Perca fluviatilis). The MeO-PBDEs, which were expected to bioaccumulate, increased in concentration accordingly up to perch, where the levels suddenly dropped dramatically. The opposite pattern was observed for OH-PBDEs, where the concentration exhibited a general trend of decline up the food web, but increased in perch, indicating metabolic demethylation of MeO-PBDEs. Debromination was also indicated to occur when progressing through the food chain resulting in high levels of tetra-brominated MeO-PBDE and OH-PBDE congeners in fish, while some penta- and hexa-brominated congeners were observed to be the dominant products in the alga. As it has been shown that OH-PBDEs are potent disruptors of oxidative phosphorylation and that mixtures of different congener may act synergistically in terms of this toxic mode of action, the high levels of OH-PBDEs detected in perch in this study warrants further investigation into potential effects of these compounds on Baltic wildlife, and monitoring of their levels. PMID:26517387

  11. Picosecond time-resolved fluorescence study on solute-solvent interaction of 2-aminoquinoline in room-temperature ionic liquids: aromaticity of imidazolium-based ionic liquids.

    PubMed

    Iwata, Koichi; Kakita, Minoru; Hamaguchi, Hiro-o

    2007-05-10

    Time-resolved fluorescence spectra and fluorescence anisotropy decay of 2-aminoquinoline (2AQ) have been measured in eight room-temperature ionic liquids, including five imidazolium-based aromatic ionic liquids and three nonaromatic ionic liquids. The same experiments have also been carried out in several ordinary molecular liquids for comparison. The observed time-resolved fluorescence spectra indicate the formation of pi-pi aromatic complexes of 2AQ in some of the aromatic ionic liquids but not in the nonaromatic ionic liquids. The fluorescence anisotropy decay data show unusually slow rotational diffusion of 2AQ in the aromatic ionic liquids, suggesting the formation of solute-solvent complexes. The probe 2AQ molecule is likely to be incorporated in the possible local structure of ionic liquids, and hence the anisotropy decays only through the rotation of the whole local structure, making the apparent rotational diffusion of 2AQ slow. The rotational diffusion time decreases rapidly by adding a small amount of acetonitrile to the solution. This observation is interpreted in terms of the local structure formation in the aromatic ionic liquids and its destruction by acetonitrile. No unusual behavior upon addition of acetonitrile has been found for the nonaromatic ionic liquids. It is argued that the aromaticity of the imidazolium cation plays a key role in the local structure formation in imidazolium-based ionic liquids. PMID:17428083

  12. Influence of polychlorinated aromatic compounds on the biotransformation and toxicity of organophosphorus pesticides (OP) to the Daphnia magna

    SciTech Connect

    Tonkopii, V.; Zagrebin, A.; Sherstneva, L.

    1995-12-31

    The effect of different polychlorinated aromatics (DDT, Aroclor 1254, certain polychlorinated biphenyls and dibenzofurans) on the toxicity of OP (DDVP paraoxon, malaoxon) to Daphnia magna was studied. Pretreatment of daphnids with chlorinated compounds during 72 hours in nontoxic concentrations (1/5--1/20 CL{sub 50}) has been shown to reduce the toxicity of OP for hydrobionts. For study of influence of chlorinated compounds on biotransformation of OP the activity of enzymes which are hydrolyzing the OP was investigated in Daphnia`s homogenates or microsomes. The activity of carboxylesterase (tributyrinase, aliesterase) and arylesterase (phosphorylphosphatase) with usage as substrates accordingly {alpha}-naphthylacetate and paraoxon was measured. Besides that the activity of cholinesterase with application of propionylthiocholine as substrate was determined. After polychlorinated aromatic compounds treatment of daphnids activities of both aryl-and carboxylesterase increased markedly. It decreased the inhibition of Daphnia`s cholinesterase caused by incubation with OP in concentrations 0.5--1.0 CL{sub 50}. Thus the induction by chlorinate aromatics of OP metabolizing enzymes seems to play the important role in reduction of OP toxicity to Daphnia magna. Perhaps the aryl- and carboxylesterase of Daphnia can be used as biomarkers of pollution by polychlorinated aromatics in water.

  13. High-field FT-ICR-MS and aromaticity equivalent approach for structural identification of water soluble organic compounds (WSOC)

    NASA Astrophysics Data System (ADS)

    Harir, Mourad; Yassine, Mahmoud M.; Dabek-Zlotorzynska, Ewa; Hertkorn, Norbert; Schmitt-Kopplin, Philippe

    2015-04-01

    Organic aerosol (OA) makes up a large and often dominant fraction, (20 to 90%) of the submicron atmospheric particulate mass, and its effects are becoming increasingly important in determining climatic and health effects of atmospheric aerosols. Despite the abundance of OA, our understanding of the sources, formation processes and atmospheric properties of OA is limited. Atmospheric OA has both primary (directly emitted) and secondary (formed in the atmosphere from precursor gases) sources, which can be natural (e.g. vegetation) and/or anthropogenic (e.g. fossil-based vehicle exhaust or biomass burning). A significant fraction of OA contains as much as 20-70% of water soluble organic compounds (WSOC). The WSOC fraction is a very complex mixture of low volatility, polyfunctional aliphatic and aromatic compounds containing carboxyl, alcohol, carbonyl, sulfo, nitro, and other functionalities. This high degree of chemical complexity of atmospheric organics has inspired a number of sophisticated approaches that are capable of identifying and detecting a variety of different analytes in OA. Accordingly, one of the most challenging areas of atmospheric particulate matter (PM) analysis is to comprehend the molecular complexity of the OA, especially WSOC fraction, a significant component of atmospheric fine PM (PM2.5). The sources of WSOC are not well understood, especially the relative contributions of primary vs. secondary organic aerosol. Therefore, the molecular characterization of WSOC is important because it allows gaining insight into aerosol sources and underlying mechanisms of secondary organic aerosols (SOA) formation and transformation. In this abstract, molecular characterization of WSOC was achieved using high-field mass spectrometry FT-ICR-MS and aromaticity equivalent approach. Aromaticity equivalent (Xc), defined recently as a new parameter calculated from the assigned molecular formulas (complementary to the aromaticity index [1]), is introduced to improve

  14. Preparation of perfluoro-1,3-propanedisulfonic acid/silica nanocomposites-encapsulated low molecular weight aromatic compounds possessing a nonflammable characteristic.

    PubMed

    Sawada, Hideo; Liu, Xinlai; Goto, Yuki; Kikuchi, Mieko; Tashima, Tsukasa; Nishida, Masakazu

    2011-04-01

    Perfluoro-1,3-propanedisulfonic acid/silica [PFPS/SiO(2)] nanocomposites were prepared by the sol-gel reactions of the corresponding disulfonic acid [PFPS] with tetraethoxysilane and silica nanoparticles under alkaline conditions. These fluorinated nanocomposites thus obtained can exhibit no weight loss behavior corresponding to the contents of PFPS in the composites after calcination at 800°C, although the parent PFPS can decompose completely around 270°C. In addition, we succeeded in encapsulation of a variety of low molecular weight aromatic compounds such as bisphenol-A, bisphenol-AF, bisphenol-F, 4,4'-biphenol and 1,1'-bi-2-naphthol into PFPS/SiO(2) nanocomposite cores. (1)H MAS NMR spectra, UV-vis spectra, fluorescence spectra and HPLC measurements of PFPS/SiO(2) nanocomposites-encapsulated bisphenol-A showed the presence of encapsulated bisphenol-A in the composites before and even after calcination at 800°C. Interestingly, it was verified that fluorescence spectra of PFPS/SiO(2) nanocomposites-encapsulated bisphenol-A after calcination at 800°C can exhibit an extremely red-shifted and enhanced fluorescence peak, compared to that before calcination or parent bisphenol-A. PMID:21256504

  15. Portable spotter for fluorescent contaminants on surfaces

    DOEpatents

    Schuresko, Daniel D.

    1980-01-01

    A portable fluorescence-based spotter for polynuclear aromatic hydrocarbon contamination on personnel and work area surfaces under ambient lighting conditions is provided. This instrument employs beam modulation and phase sensitive detection for discriminating between fluorescence from organic materials from reflected background light and inorganic fluorescent material. The device uses excitation and emission filters to provide differentiation between classes of aromatic organic compounds. Certain inorganic fluorescent materials, including heavy metal compounds, may also be distinguished from the organic compounds, despite both having similar optical properties.

  16. Polarizable Empirical Force Field for Aromatic Compounds Based on the Classical Drude Oscillator

    PubMed Central

    Lopes, Pedro E. M.; Lamoureux, Guillaume; Roux, Benoit; MacKerell, Alexander D.

    2008-01-01

    The polarizable empirical CHARMM force field based on the classical Drude oscillator has been extended to the aromatic compounds benzene and toluene. Parameters were optimized for benzene and then transferred directly to toluene, with parameters for the methyl moiety of toluene taken from the previously published work on the alkanes. Optimization of all parameters was performed against an extensive set of quantum mechanical and experimental data. Ab initio data was used for determination of the electrostatic parameters, the vibrational analysis, and in the optimization of the relative magnitudes of the Lennard-Jones parameters. The absolute values of the Lennard-Jones parameters were determined by comparing computed and experimental heats of vaporization, molecular volumes, free energies of hydration and dielectric constants. The newly developed parameter set was extensively tested against additional experimental data such as vibrational spectra in the condensed phase, diffusion constants, heat capacities at constant pressure and isothermal compressibilities including data as a function of temperature. Moreover, the structure of liquid benzene, liquid toluene and of solutions of each in water were studied. In the case of benzene, the computed and experimental total distribution function were compared, with the developed model shown to be in excellent agreement with experiment. PMID:17388420

  17. The sensitive and selective adsorption of aromatic compounds with highly crosslinked polymer nanoparticles.

    PubMed

    Liu, Shuqin; Chen, Darui; Zheng, Juan; Zeng, Lewei; Jiang, Jijun; Jiang, Ruifeng; Zhu, Fang; Shen, Yong; Wu, Dingcai; Ouyang, Gangfeng

    2015-10-28

    This study presents the preparation and characterization of a nanoscale Davankov-type hyper-crosslinked-polymer (HCP) as an adsorbent of benzene-ring-containing dyes and organic pollutants. HCP nanoparticles post-crosslinked from a poly(DVB-co-VBC) precursor were synthesized in this study, possessing ultrahigh surface area, hydrophobicity and stability. The as-synthesized Davankov-type HCP exhibited a rapid and selective adsorption ability towards the benzene-ring-containing dyes due to its highly conjugated structure. Besides, for the first time, the prepared HCP nanoparticles were adopted for the adsorption of nonpolar organic pollutants by means of solid-phase microextraction (SPME). Owing to its high hydrophobicity, diverse pore size distribution and highly conjugated structure, a 10 μm HCP coating exhibited excellent adsorption abilities towards benzene-ring-containing polycyclic aromatic hydrocarbons (PAHs) and benzene series compounds (benzene, toluene, ethylbenzene and o-xylene; abbreviated to BTEX) and to highly hydrophobic long-chain n-alkanes. Finally, the HCP-nanoparticles-coated SPME fiber was applied to the simultaneous analysis of five PAHs in environmental water samples and satisfactory recoveries were achieved. The findings could provide a new benchmark for the exploitation of superb HCPs as effective adsorbents for SPME or other adsorption applications. PMID:26416568

  18. Polycyclic aromatic compound profiles from extracts of Dreissenid mussels and gammarid amphipods coexisting in Hamilton Harbor

    SciTech Connect

    Marvin, C.H.; McCarry, B.E.; Allan, L.; Bryant, D.W.

    1995-06-01

    Aggregates of dreissenid mussels were collected in Hamilton Harbour (western Lake Ontario) from a south shore site (Randle Reef) in an area characterized by coal tar-contaminated sediments, and from a site on the north shore exposed to particulates circulating in the harbour water column. Samples were separated into three components: dreissend mussels, gammarid amphipods (Gammarus fasciatus), and particulate material. The samples were freeze-dried, and extracted using ultrasonication in dichloromethane. The organic solvent extracts were subjected to an open-column alumina and Sephadex LH-20 gel column clean-up procedure, and characterized by gas chromatography-mass spectrometry (GC-MS). The chromatographic profiles of all sample extracts were dominated by polycyclic aromatic hydrocarbons (PAH). The concentrations of the individual compounds were normalized for contaminant profile comparison of the extracts of dreissenids, amphipods, and particulates associated with aggregates of dreissenid mussels. These profiles were also compared with extracts of coal tar-contaminated sediment from the Randle Reef area, and extracts of suspended particulates obtained from sediment traps. The similarities in the PAH profiles provide evidence of exposure to a common source of contaminants. These data also show that PAH associated with suspended particulates obtained from sediment traps. The similarities in the PAH profiles provide evidence of exposure to a common source of contaminants. These data also show that PAH associated with suspended particulates in Hamilton Harbour are being accumulated by dreissenid mussels and gammarid amphipods.

  19. Characterisation of volatile organic compounds and polycyclic aromatic hydrocarbons in the ambient air of steelworks

    NASA Astrophysics Data System (ADS)

    Ciaparra, Diane; Aries, Eric; Booth, Marie-Jo; Anderson, David R.; Almeida, Susana Marta; Harrad, Stuart

    Investigations have been undertaken at two integrated steelworks in the UK to characterise airborne organic micro-pollutants and to assess the contribution of iron ore sintering and coke making operations on the air quality. Concentrations of volatile organic compounds (VOCs), namely benzene, toluene and p-xylene, were measured continuously within the boundary of a coking plant using for the first time differential optical absorption spectrometry (DOAS) between 2004 and 2006. Concentrations were obtained along two monitoring paths surrounding the coke plant and the average benzene concentration measured along both paths over the campaign was 28 μg m -3. Highest benzene concentrations were associated with winds downwind of the coke oven batteries. Concentrations of polycyclic aromatic hydrocarbons (PAHs) in ambient air were measured during 27 consecutive days in 2005 at three different locations on an integrated steelworks. PAH profiles were determined for each sampling point and compared to coke oven and sinter plant emission profiles showing an impact from the steelworks. The mean benzo [ a] pyrene concentration determined in the immediate vicinity of the coke ovens downwind from the battery was 19 ng m -3, whereas for the two other sites average benzo [ a] pyrene concentrations were much lower (around 1 ng m -3). Data were analysed using principal components analysis (PCA) and results showed that coke making and iron ore sintering were responsible for most of the variation in the PAH concentrations in the vicinity of the investigated plant.

  20. Degradation of Monochlorinated and Nonchlorinated Aromatic Compounds under Iron-Reducing Conditions

    PubMed Central

    Kazumi, J.; Haggblom, M. M.; Young, L. Y.

    1995-01-01

    The capacity for Fe(sup3+) to serve as an electron acceptor in the microbial degradation of monochlorinated and nonchlorinated aromatic compounds was investigated in anoxic sediment enrichments. The substrates tested included phenol, benzoate, aniline, their respective monochlorinated isomers, o-, m-, and p-cresol, and all six dimethylphenol isomers. Phenol and 2-, 3-, and 4-chlorophenol were utilized by anaerobic microorganisms, with the concomitant reduction of Fe(sup3+) to Fe(sup2+). The amount of Fe(sup2+) produced in the enrichments was 89 to 138% of that expected for the stoichiometric degradation of these substrates to CO(inf2), suggesting complete mineralization at the expense of Fe reduction. Under Fe-reducing conditions, there was initial loss of benzoate and 3-chlorobenzoate but not of 2- or 4-chlorobenzoate. In addition, there was initial microbial utilization of aniline but not of the chloroaniline isomers. There was also initial loss of o-, m-, and p-cresol in our enrichments. None of the dimethylphenol isomers, however, was degraded within 300 days. Furthermore, we tested the capacity of an Fe-reducing, benzoate-grown culture of Geobacter metallireducens GS-15 to utilize monochlorinated benzoates and phenols. G. metallireducens was able to degrade benzoate and phenol but none of their chlorinated isomers, suggesting that the degradation of chlorophenols in our sediment enrichments may be due to novel Fe-reducing organisms that have yet to be isolated. PMID:16535169

  1. Dehalococcoides mccartyi Strain DCMB5 Respires a Broad Spectrum of Chlorinated Aromatic Compounds

    PubMed Central

    Pöritz, Marlén; Schiffmann, Christian L.; Hause, Gerd; Heinemann, Ulrike; Seifert, Jana; Jehmlich, Nico; von Bergen, Martin; Nijenhuis, Ivonne

    2014-01-01

    Polyhalogenated aromatic compounds are harmful environmental contaminants and tend to persist in anoxic soils and sediments. Dehalococcoides mccartyi strain DCMB5, a strain originating from dioxin-polluted river sediment, was examined for its capacity to dehalogenate diverse chloroaromatic compounds. Strain DCMB5 used hexachlorobenzenes, pentachlorobenzenes, all three tetrachlorobenzenes, and 1,2,3-trichlorobenzene as well as 1,2,3,4-tetra- and 1,2,4-trichlorodibenzo-p-dioxin as electron acceptors for organohalide respiration. In addition, 1,2,3-trichlorodibenzo-p-dioxin and 1,3-, 1,2-, and 1,4-dichlorodibenzo-p-dioxin were dechlorinated, the latter to the nonchlorinated congener with a remarkably short lag phase of 1 to 4 days following transfer. Strain DCMB5 also dechlorinated pentachlorophenol and almost all tetra- and trichlorophenols. Tetrachloroethene was dechlorinated to trichloroethene and served as an electron acceptor for growth. To relate selected dechlorination activities to the expression of specific reductive dehalogenase genes, the proteomes of 1,2,3-trichlorobenzene-, pentachlorobenzene-, and tetrachloroethene-dechlorinating cultures were analyzed. Dcmb_86, an ortholog of the chlorobenzene reductive dehalogenase CbrA, was the most abundant reductive dehalogenase during growth with each electron acceptor, suggesting its pivotal role in organohalide respiration of strain DCMB5. Dcmb_1041 was specifically induced, however, by both chlorobenzenes, whereas 3 putative reductive dehalogenases, Dcmb_1434, Dcmb_1339, and Dcmb_1383, were detected only in tetrachloroethene-grown cells. The proteomes also harbored a type IV pilus protein and the components for its assembly, disassembly, and secretion. In addition, transmission electron microscopy of DCMB5 revealed an irregular mode of cell division as well as the presence of pili, indicating that pilus formation is a feature of D. mccartyi during organohalide respiration. PMID:25381236

  2. Aromatic compound emissions from municipal solid waste landfill: Emission factors and their impact on air pollution

    NASA Astrophysics Data System (ADS)

    Liu, Yanjun; Lu, Wenjing; Guo, Hanwen; Ming, Zhongyuan; Wang, Chi; Xu, Sai; Liu, Yanting; Wang, Hongtao

    2016-08-01

    Aromatic compounds (ACs) are major components of volatile organic compounds emitted from municipal solid waste (MSW) landfills. The ACs emissions from the working face of a landfill in Beijing were studied from 2014 to 2015 using a modified wind tunnel system. Emission factors (EFs) of fugitive ACs emissions from the working face of the landfill were proposed according to statistical analyses to cope with their uncertainty. And their impacts on air quality were assessed for the first time. Toluene was the dominant AC with an average emission rate of 38.8 ± 43.0 μg m-2 s-1 (at a sweeping velocity of 0.26 m s-1). An increasing trend in AC emission rates was observed from 12:00 to 18:00 and then peaked at 21:00 (314.3 μg m-2 s-1). The probability density functions (PDFs) of AC emission rates could be classified into three distributions: Gaussian, log-normal, and logistic. EFs of ACs from the working face of the landfill were proposed according to the 95th percentile cumulative emission rates and the wind effects on ACs emissions. The annual ozone formation and secondary organic aerosol formation potential caused by AC emissions from landfills in Beijing were estimated to be 8.86 × 105 kg year-1 and 3.46 × 104 kg year-1, respectively. Toluene, m + p-xylene, and 1,3,5-trimethylbenzene were the most significant contributors to air pollution. Although ACs pollutions from landfills accounts for less percentage (∼0.1%) compared with other anthropogenic sources, their fugitive emissions which cannot be controlled efficiently deserve more attention and further investigation.

  3. Parametric investigation of laser-induced fluorescence of solid-state uranyl compounds.

    PubMed

    Wang, Guangjun; Su, Yi; Monts, David L

    2008-10-23

    The combination of remote/standoff sensing and laser-induced fluorescence (LIF) spectroscopy shows potential for detection of uranyl (UO2(2+)) compounds. Uranyl compounds exhibit characteristic emission in the 450-600 nm (22,200 to 16,700 cm(-1)) spectral region when excited by wavelengths in the ultraviolet or in the short-wavelength portion of the visible spectrum. We report a parametric study of the effects of excitation wavelength [including 532 nm (18,797 cm(-1)), 355 nm (28,169 cm(-1)), and 266 nm (37,594 cm(-1))] and excitation laser power on solid-state uranium compounds. The uranium compounds investigated include uranyl nitrate, uranyl sulfate, uranyl oxalate, uranium dioxide, triuranium octaoxide, uranyl acetate, uranyl formate, zinc uranyl acetate, and uranyl phosphate. We observed the characteristic uranyl fluorescence spectrum from the uranium compounds except for uranium oxide compounds (which do not contain the uranyl moiety) and for uranyl formate, which has a low fluorescence quantum yield. Relative uranyl fluorescence intensity is greatest for 355 nm excitation, and the order of decreasing fluorescence intensity with excitation wavelength (relative intensity/laser output) is 355 nm > 266 nm > 532 nm. For 532 nm excitation, the emission spectrum is produced by two-photon excitation. Uranyl fluorescence intensity increases linearly with increasing laser power, but the rate of fluorescence intensity increase is different for different emission bands. PMID:18823105

  4. Accelerated aromatic compounds degradation in aquatic environment by use of interaction between Spirodela polyrrhiza and bacteria in its rhizosphere.

    PubMed

    Toyama, Tadashi; Yu, Ning; Kumada, Hirohide; Sei, Kazunari; Ike, Michihiko; Fujita, Masanori

    2006-04-01

    Accelerated degradation of organic chemicals by aquatic plant-bacterial associations was reported for the first time with elucidation of the role and contribution of aquatic plant and bacteria in its rhizosphere using a fast-growing giant duckweed, Spirodela polyrrhiza. The results clearly showed the accelerated degradation of all the three aromatic compounds (phenol, aniline and 2,4-dichlorophenol [2,4-DCP]) tested by aquatic plant-bacterial associations. In phenol degradation system, phenol-degrading bacteria indigenous to the rhizosphere fraction of S. polyrrhiza mainly contributed, while in aniline degradation system S. polyrrhiza mainly contributed by stimulating aniline-degrading bacteria both in the rhizosphere and balk water fraction. On the other hand in 2,4-DCP degradation system, S. polyrrhiza itself mainly contributed to its removal by uptake and degradation. Thus, the mechanisms for accelerated removal of aromatic compounds were quite different depending on the substrates. S. polyrrhiza showed selective accumulation of phenol-degrading bacteria in its rhizosphere fraction, while aniline- and 2,4-DCP-degrading bacteria were not much accumulated. S. polyrrhiza secreted peroxidase and laccase. However, both of the enzymatic activities increased with the addition of aromatic compounds, degrading ability of S. polyrrhiza itself should be owing to the production of peroxidase rather than laccase because the change of peroxidase activity and concentration of each aromatic compound well concurred. From the results obtained in the present study, it can be concluded that the feasibility of the use of aquatic plant-bacterial associations to accelerate the degradation of organic chemicals especially recalcitrant compounds in aquatic environment was shown. PMID:16716944

  5. Interaction of aromatic compounds with xenon: spectroscopic and computational characterization for the cases of p-cresol and toluene.

    PubMed

    Cao, Qian; Andrijchenko, Natalya; Ermilov, Alexander; Räsänen, Markku; Nemukhin, Alexander; Khriachtchev, Leonid

    2015-03-19

    We have investigated noncovalent interactions of two aromatic compounds (toluene and p-cresol) with Xe atoms by using infrared spectroscopy in a Ne matrix and quantum chemical calculations. The present results show that the methyl group of these molecules is a sensitive probe of the interaction with Xe. We have used the molecules with the deuterated methyl group, possessing a relatively simple spectrum, which allows us to detect characteristic vibrational shifts in the complexes, in which a Xe atom interacts with the aromatic π electron system (π structure). For the p-cresol···Xe complex, we also observed evidence of the 1:1 H-bonded structure. The amount of the H-bonded structure of the cresol···Xe complex is relatively small, which agrees with the calculated interaction energies (stronger interaction for the π structure). The bands of the 1:1 complexes of p-cresol and toluene with Xe appear at low Xe concentration and their intensities relative to the monomer bands are nearly proportional to the Xe/Ne concentration ratio. For the p-cresol-Xe system, additional OH stretching bands appear at higher Xe concentrations, which are suitable for the complexes with several Xe atoms. The π structures studied in this work can probably be formed in the case of aromatic amino acids, for which these simple aromatic compounds are useful models. PMID:25360812

  6. Genetic analysis of Indian aromatic and quality rice (Oryza sativa L.) germplasm using panels of fluorescently-labeled microsatellite markers.

    PubMed

    Jain, Sunita; Jain, Rajinder K; McCouch, Susan R

    2004-09-01

    Genetic relationships among Indian aromatic and quality rice (Oryza sativa) germplasm were assessed using 30 fluorescently labeled rice microsatellite markers. The 69 rice genotypes used in this study included 52 Basmati and other scented/quality rice varieties from different parts of India and 17 indica and japonica varieties that served as controls. A total of 235 alleles were detected at the 30 simple sequence repeat (SSR) loci, 62 (26.4%) of which were present only in Basmati and other scented/quality rice germplasm accessions. The number of alleles per locus ranged from 3 to 22, with an average of 7.8, polymorphism information content (PIC) values ranged from 0.2 to 0.9, with an average of 0.6, and the size range between the smallest and the largest allele for a given microsatellite locus varied between 3 bp and 68 bp. Of the 30 SSR markers, 20 could distinguish traditional Basmati rice varieties, and a single panel of eight markers could be used to differentiate the premium traditional Basmati, cross-bred Basmati, and non-Basmati rice varieties having different commercial value in the market-place. When estimates of inferred ancestry or similarity coefficients were used to cluster varieties, the high-quality Indian aromatic and quality rice genotypes could be distinguished from both indica and japonica cultivars, and crossbred varieties could be distinguished from traditional Basmati rices. The results indicate that Indian aromatic and quality germplasm is genetically distinct from other groups within O. sativa and is the product of a long independent pattern of evolution. The data also suggest that there is scope for exploiting the genetic diversity of aromatic/quality rice germplasm available in India for national Basmati rice breeding programs. PMID:15309297

  7. Spectroscopic properties and laser induced fluorescence determination of some endocrine disrupting compounds.

    PubMed

    Benmansour, Badr; Stephan, Ludovic; Cabon, Jean-Yves; Deschamps, Laure; Giamarchi, Philippe

    2011-05-01

    This work presents spectroscopic properties of some Endocrine Disrupting Compounds (EDCs), frequently found in food and in natural water. Studied molecules belong to the groups of phenolic and phthalate EDCs. In a first part, we have examined their absorption and fluorescence properties. Fluorescence emission wavelengths are about 300 nm for phenolic compounds and 360 nm for phtalate compounds; main excitation wavelengths being comprised between 210 nm and 230 nm. Fluorescence lifetimes measured are short (about 4 ns) and the fluorescence quantum yield has been determined. In a second part, to avoid the time consuming solvent extraction step, an analytical application to evaluate the performance of a direct analysis by laser induced fluorescence spectroscopy of ECDs traces in tap water and in raw water is presented. Good detection limits have been obtained, i.e.: 0.35 µg.L(-1) of chlorophenol in tap water, which are always lower than the reported Predictive Non Efficient Concentration (PNEC). PMID:20084436

  8. Responses of mixtures of polyhalogenated aromatic compounds or single compounds in the CALUX-assay a novel species-specific bioassay for Ah-receptor active compounds

    SciTech Connect

    Murk, A.J.; Aarts, J.M.M.J.G.; Jonas, A.; Brouwer, A.; Denison, M.S.

    1995-12-31

    Polyhalogenated aromatic hydrocarbons (PHAHs) elicit a number of common toxic responses, including reproductive toxicity, teratogenicity, impairment of immune responses, alterations in vitamin A and thyroid hormone metabolism and carcinogenesis. The toxic effects however are highly dependent on the animal species used, The most toxic PHAHs are approximate isostereomeres of 2,3,7,8 tetrachlorinated dibenzo-p-dioxin (TCDD) and share a common mechanism of action mediated by the aryl hydrocarbon receptor (AhR). Based on the common receptor mediated mechanism, the toxic equivalency factor concept was developed, in which the potency of each individual congener is expressed relative to TCDD, thus allowing hazard and risk assessment for mixtures of PHAHs. A number of recombinant cell lines were developed, including hepalclc7 mouse and H4IIE rat hepatoma cell lines, with AhR-mediated firefly (Photinus pyralis) luciferase gene expression. The response in this so-called CALUX (chemical activated luciferase expression) assay is additive for polychlorinated dibenzofurans (PCDFs) and PCDDS, but for polychlorinated biphenyls (PCBs) both synergistic and antagonistic interactions have been demonstrated, which are partially species-dependent. Also some structurally related compounds, like polybrominated diphenyl ether, pentachlorinated phenol, benzo(a)pyrene, pyrene, tetrachlorobenzyltoluene (Ugilec 141) and mixtures of polychlorinated terphenyls have been tested in the CALUX assay. The responses of these compounds were sometimes agonistic, but also antagonistic and synergistic effects on the TCDO response were observed.

  9. Diurnal variability of polycyclic aromatic compound (PAC) concentrations: Relationship with meteorological conditions and inferred sources

    NASA Astrophysics Data System (ADS)

    Alam, Mohammed S.; Keyte, Ian J.; Yin, Jianxin; Stark, Christopher; Jones, Alan M.; Harrison, Roy M.

    2015-12-01

    Polycyclic aromatic hydrocarbons (PAH) and their nitro and oxy derivatives have been sampled every three hours over one week in winter at two sites in Birmingham UK. One site is heavily influenced by road traffic and is close to residential dwellings, while the other site is a background urban location at some distance from both sources of emission. The time series of concentrations has been examined along with the ratio of concentrations between the two sampling sites. A comparison of averaged diurnal profiles has shown different patterns of behaviour which has been investigated through calculating ratios of concentration at 18:00-21:00 h relative to that at 06:00-09:00 h. This allows identification of those compounds with a strong contribution to a traffic-related maximum at 06:00-09:00 h which are predominantly the low molecular weight PAHs, together with a substantial group of quinones and nitro-PAHs. Changes in partitioning between vapour and particulate forms are unlikely to influence the ratio as the mean temperature at both times was almost identical. Most compounds show an appreciable increase in concentrations in the evening which is attributed to residential heating emissions. Compounds dominated by this source show high ratios of 18:00-21:00 concentrations relative to 06:00-09:00 concentrations and include higher molecular weight PAH and a substantial group of both quinones and nitro-PAH. The behaviour of retene, normally taken as an indicator of biomass burning, is suggestive of wood smoke only being one contributor to the evening peak in PAH and their derivatives, with coal combustion presumably being the other main contributor. Variations of PAH concentrations with wind speed show a dilution behaviour consistent with other primary pollutants, and high concentrations of a range of air pollutants were observed in an episode of low temperatures and low wind speeds towards the end of the overall sampling period consistent with poor local dispersion

  10. A novel aromatic oil compound inhibits microbial overgrowth on feet: a case study

    PubMed Central

    Misner, Bill D

    2007-01-01

    Background Athlete's Foot (Tinea pedis) is a form of ringworm associated with highly contagious yeast-fungi colonies, although they look like bacteria. Foot bacteria overgrowth produces a harmless pungent odor, however, uncontrolled proliferation of yeast-fungi produces small vesicles, fissures, scaling, and maceration with eroded areas between the toes and the plantar surface of the foot, resulting in intense itching, blisters, and cracking. Painful microbial foot infection may prevent athletic participation. Keeping the feet clean and dry with the toenails trimmed reduces the incidence of skin disease of the feet. Wearing sandals in locker and shower rooms prevents intimate contact with the infecting organisms and alleviates most foot-sensitive infections. Enclosing feet in socks and shoes generates a moisture-rich environment that stimulates overgrowth of pungent both aerobic bacteria and infectious yeast-fungi. Suppression of microbial growth may be accomplished by exposing the feet to air to enhance evaporation to reduce moistures' growth-stimulating effect and is often neglected. There is an association between yeast-fungi overgrowths and disabling foot infections. Potent agents virtually exterminate some microbial growth, but the inevitable presence of infection under the nails predicts future infection. Topical antibiotics present a potent approach with the ideal agent being one that removes moisture producing antibacterial-antifungal activity. Severe infection may require costly prescription drugs, salves, and repeated treatment. Methods A 63-y female volunteered to enclose feet in shoes and socks for 48 hours. Aerobic bacteria and yeast-fungi counts were determined by swab sample incubation technique (1) after 48-hours feet enclosure, (2) after washing feet, and (3) after 8-hours socks-shoes exposure to a aromatic oil powder-compound consisting of arrowroot, baking soda, basil oil, tea tree oil, sage oil, and clove oil. Conclusion Application of this

  11. Petroleum alteration by thermochemical sulfate reduction - A comprehensive molecular study of aromatic hydrocarbons and polar compounds

    NASA Astrophysics Data System (ADS)

    Walters, Clifford C.; Wang, Frank C.; Qian, Kuangnan; Wu, Chunping; Mennito, Anthony S.; Wei, Zhibin

    2015-03-01

    Thermochemical sulfate reduction (TSR) alters petroleum composition as it proceeds towards the complete oxidation of hydrocarbons to CO2. The effects of TSR on the molecular and isotopic composition of volatile species are well known; however, the non-volatile higher molecular weight aromatic and polar species have not been well documented. To address this deficiency, a suite of onshore Gulf coast oils and condensates generated from and accumulating in Smackover carbonates was assembled to include samples that experienced varying levels of TSR alteration and in reservoir thermal cracking. The entire molecular composition of aromatic hydrocarbons and NSO species were characterized and semi-quantified using comprehensive GC × GC (FID and CSD) and APPI-FTICR-MS. The concentration of thiadiamondoids is a reliable indicator of the extent of TSR alteration. Once generated by TSR, thiadiamondoids remain thermally stable in all but the most extreme reservoir temperatures (>180 °C). Hydrocarbon concentrations and distributions are influenced by thermal cracking and TSR. With increasing TSR alteration, oils become enriched in monoaromatic hydrocarbons and the distribution of high molecular weight aromatic hydrocarbons shifts towards more condensed species with a decrease in the number of alkyl carbons. Organosulfur compounds are created by the TSR process. In addition to the increase in benzothiophenes and dibenzothiophenes noted in previous studies, TSR generates condensed species containing one or more sulfur atoms that likely are composed of a single or multiple thiophenic cores. We hypothesize that these species are generated from the partial oxidation of PAHs and dealkylation reactions, followed by sulfur incorporation and condensation reactions. The organosulfur species remaining in the TSR altered oils are "proto-solid bitumen" moieties that upon further condensation, oxidation or sulfur incorporation result in highly sulfur enriched solid bitumen, which is

  12. Inhibitory effect of synthetic aromatic heterocycle thiosemicarbazone derivatives on mushroom tyrosinase: Insights from fluorescence, (1)H NMR titration and molecular docking studies.

    PubMed

    Xie, Juan; Dong, Huanhuan; Yu, Yanying; Cao, Shuwen

    2016-01-01

    Three structurally similar aromatic heterocyclic compounds 2-thiophenecarboxaldehyde (a), 2-furaldehyde (b), 2-pyrrolecarboxaldehyde (c) were chosen and a series of their thiosemicarbazone derivatives(1a-3a, 1b-3b and 1c-3c) were synthesized to evaluate their biological activities as mushroom tyrosinase inhibitors. The inhibitory effects of these compounds on tyrosinase were investigated by using spectrofluorimetry, (1)H NMR titration and molecular docking techniques. From the results of fluorescence spectrum and (1)H NMR titration, it was found that forming complexes between the sulfur atom from thiourea and copper ion of enzyme center may play a key role for inhibition activity. Moreover, investigation of (1)H NMR spectra further revealed that formation of hydrogen bond between inhibitor and enzyme may be helpful to above complexes formation. The results were well coincident with the suggestion of molecular docking and obviously showed that 2-thiophone N(4)-thiosemicarbazone (1a), 2-furfuran N(4)-thiosemicarbazone (1b) and 2-pyrrole N(4)-thiosemicarbazone (1c) are potential inhibitors which deserves further investigation. PMID:26213029

  13. Overcoming compound fluorescence in the FLiK screening assay with red-shifted fluorophores.

    PubMed

    Schneider, Ralf; Gohla, Anne; Simard, Jeffrey R; Yadav, Dharmendra B; Fang, Zhizhou; van Otterlo, Willem A L; Rauh, Daniel

    2013-06-01

    In the attempt to discover novel chemical scaffolds that can modulate the activity of disease-associated enzymes, such as kinases, biochemical assays are usually deployed in high-throughput screenings. First-line assays, such as activity-based assays, often rely on fluorescent molecules by measuring a change in the total emission intensity, polarization state, or energy transfer to another fluorescent molecule. However, under certain conditions, intrinsic compound fluorescence can lead to difficult data analysis and to false-positive, as well as false-negative, hits. We have reported previously on a powerful direct binding assay called fluorescent labels in kinases ('FLiK'), which enables a sensitive measurement of conformational changes in kinases upon ligand binding. In this assay system, changes in the emission spectrum of the fluorophore acrylodan, induced by the binding of a ligand, are translated into a robust assay readout. However, under the excitation conditions of acrylodan, intrinsic compound fluorescence derived from highly conjugated compounds complicates data analysis. We therefore optimized this method by identifying novel fluorophores that excite in the far red, thereby avoiding compound fluorescence. With this advancement, even rigid compounds with multiple π-conjugated ring systems can now be measured reliably. This study was performed on three different kinase constructs with three different labeling sites, each undergoing distinct conformational changes upon ligand binding. It may therefore serve as a guideline for the establishment of novel fluorescence-based detection assays. PMID:23672540

  14. Simultaneous Catabolism of Plant-Derived Aromatic Compounds Results in Enhanced Growth for Members of the Roseobacter Lineage

    PubMed Central

    Gulvik, Christopher A.

    2013-01-01

    Plant-derived aromatic compounds are important components of the dissolved organic carbon pool in coastal salt marshes, and their mineralization by resident bacteria contributes to carbon cycling in these systems. Members of the roseobacter lineage of marine bacteria are abundant in coastal salt marshes, and several characterized strains, including Sagittula stellata E-37, utilize aromatic compounds as primary growth substrates. The genome sequence of S. stellata contains multiple, potentially competing, aerobic ring-cleaving pathways. Preferential hierarchies in substrate utilization and complex transcriptional regulation have been demonstrated to be the norm in many soil bacteria that also contain multiple ring-cleaving pathways. The purpose of this study was to ascertain whether substrate preference exists in S. stellata when the organism is provided a mixture of aromatic compounds that proceed through different ring-cleaving pathways. We focused on the protocatechuate (pca) and the aerobic benzoyl coenzyme A (box) pathways and the substrates known to proceed through them, p-hydroxybenzoate (POB) and benzoate, respectively. When these two substrates were provided at nonlimiting carbon concentrations, temporal patterns of cell density, gene transcript abundance, enzyme activity, and substrate concentrations indicated that S. stellata simultaneously catabolized both substrates. Furthermore, enhanced growth rates were observed when S. stellata was provided both compounds simultaneously compared to the rates of cells grown singly with an equimolar concentration of either substrate alone. This simultaneous-catabolism phenotype was also demonstrated in another lineage member, Ruegeria pomeroyi DSS-3. These findings challenge the paradigm of sequential aromatic catabolism reported for soil bacteria and contribute to the growing body of physiological evidence demonstrating the metabolic versatility of roseobacters. PMID:23563956

  15. Application of mesoporous carbon as a solid-phase microextraction fiber coating for the extraction of volatile aromatic compounds.

    PubMed

    Zhang, Xi; Zang, Xiaohuan; Zhang, Guijiang; Wang, Chun; Wang, Zhi

    2015-08-01

    A mesoporous carbon was fabricated using MCM-41 as a template and sucrose as a carbon source. The carbon material was coated on stainless-steel wires by using the sol-gel technique. The prepared solid-phase microextraction fiber was used for the extraction of five volatile aromatic compounds (chlorobenzene, ethylbenzene, o-xylene, bromobenzene, and 4-chlorotoluene) from tea beverage samples (red tea and green tea) prior to gas chromatography with mass spectrometric detection. The main experimental parameters affecting the extraction of the volatile aromatic compounds by the fiber, including the extraction time, sample volume, extraction temperature, salt addition, and desorption conditions, were investigated. The linearity was observed in the range from 0.1 to 10.0 μg/L with the correlation coefficients (r) ranging from 0.9923 to 0.9982 and the limits of detection were less than 10.0 ng/L. The recoveries of the volatile aromatic compounds by the method from tea beverage samples at spiking levels of 1.0 and 10.0 μg/L ranged from 73.1 to 99.1%. PMID:26041569

  16. Enhancing muconic acid production from glucose and lignin-derived aromatic compounds via increased protocatechuate decarboxylase activity

    DOE PAGESBeta

    Johnson, Christopher W.; Salvachua, Davinia; Khanna, Payal; Smith, Holly; Peterson, Darren J.; Beckham, Gregg T.

    2016-04-22

    The conversion of biomass-derived sugars and aromatic molecules to cis,cis-muconic acid (referred to hereafter as muconic acid or muconate) has been of recent interest owing to its facile conversion to adipic acid, an important commodity chemical. Metabolic routes to produce muconate from both sugars and many lignin-derived aromatic compounds require the use of a decarboxylase to convert protocatechuate (PCA, 3,4-dihydroxybenzoate) to catechol (1,2-dihydroxybenzene), two central aromatic intermediates in this pathway. Several studies have identified the PCA decarboxylase as a metabolic bottleneck, causing an accumulation of PCA that subsequently reduces muconate production. A recent study showed that activity of the PCAmore » decarboxylase is enhanced by co-expression of two genetically associated proteins, one of which likely produces a flavin-derived cofactor utilized by the decarboxylase. Using entirely genome-integrated gene expression, we have engineered Pseudomonas putida KT2440-derived strains to produce muconate from either aromatic molecules or sugars and demonstrate in both cases that co-expression of these decarboxylase associated proteins reduces PCA accumulation and enhances muconate production relative to strains expressing the PCA decarboxylase alone. In bioreactor experiments, co-expression increased the specific productivity (mg/g cells/h) of muconate from the aromatic lignin monomer p-coumarate by 50% and resulted in a titer of >15 g/L. In strains engineered to produce muconate from glucose, co-expression more than tripled the titer, yield, productivity, and specific productivity, with the best strain producing 4.92+/-0.48 g/L muconate. Furthermore, this study demonstrates that overcoming the PCA decarboxylase bottleneck can increase muconate yields from biomass-derived sugars and aromatic molecules in industrially relevant strains and cultivation conditions.« less

  17. The sensitive and selective adsorption of aromatic compounds with highly crosslinked polymer nanoparticles

    NASA Astrophysics Data System (ADS)

    Liu, Shuqin; Chen, Darui; Zheng, Juan; Zeng, Lewei; Jiang, Jijun; Jiang, Ruifeng; Zhu, Fang; Shen, Yong; Wu, Dingcai; Ouyang, Gangfeng

    2015-10-01

    This study presents the preparation and characterization of a nanoscale Davankov-type hyper-crosslinked-polymer (HCP) as an adsorbent of benzene-ring-containing dyes and organic pollutants. HCP nanoparticles post-crosslinked from a poly(DVB-co-VBC) precursor were synthesized in this study, possessing ultrahigh surface area, hydrophobicity and stability. The as-synthesized Davankov-type HCP exhibited a rapid and selective adsorption ability towards the benzene-ring-containing dyes due to its highly conjugated structure. Besides, for the first time, the prepared HCP nanoparticles were adopted for the adsorption of nonpolar organic pollutants by means of solid-phase microextraction (SPME). Owing to its high hydrophobicity, diverse pore size distribution and highly conjugated structure, a 10 μm HCP coating exhibited excellent adsorption abilities towards benzene-ring-containing polycyclic aromatic hydrocarbons (PAHs) and benzene series compounds (benzene, toluene, ethylbenzene and o-xylene; abbreviated to BTEX) and to highly hydrophobic long-chain n-alkanes. Finally, the HCP-nanoparticles-coated SPME fiber was applied to the simultaneous analysis of five PAHs in environmental water samples and satisfactory recoveries were achieved. The findings could provide a new benchmark for the exploitation of superb HCPs as effective adsorbents for SPME or other adsorption applications.This study presents the preparation and characterization of a nanoscale Davankov-type hyper-crosslinked-polymer (HCP) as an adsorbent of benzene-ring-containing dyes and organic pollutants. HCP nanoparticles post-crosslinked from a poly(DVB-co-VBC) precursor were synthesized in this study, possessing ultrahigh surface area, hydrophobicity and stability. The as-synthesized Davankov-type HCP exhibited a rapid and selective adsorption ability towards the benzene-ring-containing dyes due to its highly conjugated structure. Besides, for the first time, the prepared HCP nanoparticles were adopted for the

  18. Genotoxicity assessment of the antiepileptic drug AMP397, an Ames-positive aromatic nitro compound.

    PubMed

    Suter, Willi; Hartmann, Andreas; Poetter, Franziska; Sagelsdorff, Peter; Hoffmann, Peter; Martus, Hans-Jörg

    2002-07-25

    AMP397 is a novel antiepileptic agent and the first competitive AMPA antagonist with high receptor affinity, good in vivo potency, and oral activity. AMP397 has a structural alert (aromatic nitro group) and was mutagenic in Salmonella typhimurium strains TA97a, TA98 and TA100 without S9, but negative in the nitroreductase-deficient strains TA98NR and TA100NR. The amino derivative of AMP397 was negative in wild-type strains TA98 and TA100. AMP397 was negative in a mouse lymphoma tk assay, which included a 24h treatment without S9. A weak micronucleus induction in vitro was found at the highest concentrations tested in V79 cells with S9. AMP397 was negative in the following in vivo studies, which included the maximum tolerated doses of 320mg/kg in mice and 2000mg/kg in rats: MutaMouse assay in colon and liver (5x320mg/kg) at three sampling times (3, 7 and 31 days after the last administration); DNA binding study in the liver of mice and rats after a single treatment with [14C]-AMP397; comet assay (1x2000mg/kg) in jejunum and liver of rats, sampling times 3 and 24h after administration; micronucleus test (2x320mg/kg) in the bone marrow of mice, sampling 24h after the second administration. Based on these results, it was concluded that AMP397 has no genotoxic potential in vivo. In particular, no genotoxic metabolite is formed in mammalian cells, and, if formed by intestinal bacteria, is unable to exert any genotoxic activity in the adjacent intestinal tissue. These data were considered to provide sufficient safety to initiate clinical development of the compound. PMID:12113769

  19. Oil sands development contributes polycyclic aromatic compounds to the Athabasca River and its tributaries

    PubMed Central

    Kelly, Erin N.; Short, Jeffrey W.; Schindler, David W.; Hodson, Peter V.; Ma, Mingsheng; Kwan, Alvin K.; Fortin, Barbra L.

    2009-01-01

    For over a decade, the contribution of oil sands mining and processing to the pollution of the Athabasca River has been controversial. We show that the oil sands development is a greater source of contamination than previously realized. In 2008, within 50 km of oil sands upgrading facilities, the loading to the snowpack of airborne particulates was 11,400 T over 4 months and included 391 kg of polycyclic aromatic compounds (PAC), equivalent to 600 T of bitumen, while 168 kg of dissolved PAC was also deposited. Dissolved PAC concentrations in tributaries to the Athabasca increased from 0.009 μg/L upstream of oil sands development to 0.023 μg/L in winter and to 0.202 μg/L in summer downstream. In the Athabasca, dissolved PAC concentrations were mostly <0.025 μg/L in winter and 0.030 μg/L in summer, except near oil sands upgrading facilities and tailings ponds in winter (0.031–0.083 μg/L) and downstream of new development in summer (0.063–0.135 μg/L). In the Athabasca and its tributaries, development within the past 2 years was related to elevated dissolved PAC concentrations that were likely toxic to fish embryos. In melted snow, dissolved PAC concentrations were up to 4.8 μg/L, thus, spring snowmelt and washout during rain events are important unknowns. These results indicate that major changes are needed to the way that environmental impacts of oil sands development are monitored and managed. PMID:19995964

  20. Formation of environmentally persistent free radicals from the heterogeneous reaction of ozone and polycyclic aromatic compounds.

    PubMed

    Borrowman, Cuyler K; Zhou, Shouming; Burrow, Timothy E; Abbatt, Jonathan P D

    2016-01-01

    In the 1980s long-lived radical species were identified in cigarette tar. Since then, environmentally persistent free radicals (EPFRs) have been observed in ambient particulate matter, and have been generated in particulate matter generated from internal combustion engines. For the first time, we measure in situ the formation and decay of EPFRs through the heterogeneous reaction of ozone and several polycyclic aromatic compounds (PAC). Solid anthracene (ANT), pyrene (PY), benzo[a]pyrene (BAP), benzo[ghi]perylene (BGHIP), 1,4-naphthoquinone (1,4NQ), and 9,10-anthraquinone (AQ) were reacted with gas-phase ozone in a flow system placed in the active cavity of an electron paramagnetic resonance (EPR) spectrometer, and the formation of radicals was measured on the timescale of tens of minutes at ambient levels of ozone down to 30 ppb. For most substrates the net radical production is initially rapid, slows at intermediate times, and is followed by a slow decay. For oxidized solid BAP, radical signal persists for many days in the absence of ozone. To evaluate the effect of substrate phase, the solid PAHs were also dissolved in squalane, an organic oil inert to ozone, which yielded a much higher maximum radical concentration and faster radical decay when exposed to ozone. With higher mobility, reactants were apparently able to more easily diffuse and react with each other, yielding the higher radical concentrations. The EPR spectra exhibit three radicals types, two of which have been assigned to semiquinone species and one to a PAH-derived, carbon-centered radical. Although our system uses levels of PAC not typically found in the environment it is worth noting that the amounts of radical formed, on the order of 10(18) radicals per g, are comparable to those observed in ambient particulate matter. PMID:26603953

  1. An accurate benchmark description of the interactions between carbon dioxide and polyheterocyclic aromatic compounds containing nitrogen.

    PubMed

    Li, Sicheng; Smith, Daniel G A; Patkowski, Konrad

    2015-07-01

    We assessed the performance of a large variety of modern density functional theory approaches for the adsorption of carbon dioxide on molecular models of pyridinic N-doped graphene. Specifically, we selected eight polyheterocyclic aromatic compounds ranging from pyridine and pyrazine to 1,6-diazacoronene and investigated their complexes with CO2 for a large range of intermolecular distances and including both in-plane and stacked orientations. The benchmark interaction energies were computed at the complete-basis-set limit MP2 level plus a CCSD(T) coupled-cluster correction in a moderate but carefully selected basis set. Using a set of 96 benchmark CCSD(T)-level interaction energies as a reference, we investigated the accuracy of DFT-based approaches as a function of the density functional, the dispersion correction, the basis set, and the counterpoise correction or lack thereof. While virtually all DFT variants exhibit some deterioration of accuracy for distances slightly shorter than the van der Waals minima, we were able to identify several schemes such as B2PLYP-D3 and M05-2X-D3 whose average errors on the entire benchmark data set are in the 5-10% range. The top DFT performers were subsequently used to investigate the energy profile for a carbon dioxide transition through model N-doped graphene pores. All investigated methods confirmed that the largest, N4H4 pore allows for a barrierless CO2 transition to the other side of a graphene sheet. PMID:26055458

  2. Polyphenoloxidases immobilized in organic gels: Properties and applications in the detoxification of aromatic compounds

    SciTech Connect

    Crecchio, C.; Ruggiero, P.; Pizzigallo, M.D.R.

    1995-12-20

    Gelatine gels originate from water in oil microemulsions in which the ternary system consists of isooctane/sulfosuccinic acid bis [2-ethyl hexyl] ester/water; the solubilization of gelatin in the water pool of these microemulsions transforms them into viscous gels in which it is possible to cosolubilize various reactive molecules. These gels were used to immobilize two phenoloxidases, a laccase from Trametes versicolor and a tyrosinase from mushroom. The best balance between gel retention and catalytic activity was reached at a gelatine concentration of 2.5% (w/v) in the case of tyrosinase, while laccase immobilization was independent of gelatine concentration. Both enzymes kept the same optimum pH as the corresponding soluble controls, while a partial loss of activity was observed when they were immobilized. Immobilized enzymes showed an increased stability when incubated for several days at 4 C with a very low release from the gels in the incubation solutions. The immobilization of tyrosinase and of laccase enhanced stability to thermal inactivation. Furthermore, gel-entrapped tyrosinase was almost completely preserved from proteolysis: more than 80% of the activity was maintained, while only 25% of the soluble control activity was detected after the same proteolytic treatments. A column packed with gel-immobilized tyrosinase was used to demonstrate that enzymes immobilized with this technique may be reused several times in the same reaction without loosing their efficiency. Finally, gel-entrapped tyrosinase and laccase were capable of removing naturally occurring and xenobiotic aromatic compounds from aqueous suspensions with different degrees of efficiency.

  3. Green fluorescent protein-doped sol-gel silica planar waveguide to detect organophosphorus compound

    NASA Astrophysics Data System (ADS)

    Enami, Y.; Suye, S.

    2012-02-01

    We report novel living protein-doped planar waveguide, and real-time detection of an organophosphorus compound using a sol-gel silica planar waveguide doped with a green fluorescent protein and an organophosphorus hydrolase on a yeast-cell surface. The waveguide was pumped at 488 nm, and emitted green fluorescence at the far field. The green fluorescent light at 550 nm changed by 50% from the original power 1 min after application of the organophosphorus compound. The results enable the real-time detection of biochemical weapon and insecticide harmful for human body by using an in-line fiber sensor network.

  4. Laser-induced fluorescence studies of polycyclic aromatic hydrocarbons (PAH) vapors at high temperatures.

    PubMed

    Chi, Z; Cullum, B M; Stokes, D L; Mobley, J; Miller, G H; Hajaligol, M R; Vo-Dinh, T

    2001-06-01

    In this work, we present the fluorescence spectra of anthracene and pyrene vapors at different elevated temperatures (from 150 to 650 degrees C) excited with the 337 nm line of a nitrogen laser. We describe the high temperature effects on the resulting spectral properties including spectral intensity, spectral bandwidth and spectral shift. We found that the PAH fluorescence spectral bandwidths become very broad as the temperature increases. The broadening is mainly due to thermal vibrational sequence congestion. We also have found that the fluorescence intensity of pyrene vapor increases with increasing temperature, which results from the increase of the pyrene vapor absorption cross section at 337 nm. PMID:11446693

  5. Chemical characterization of aromatic compounds in extra heavy gas oil by comprehensive two-dimensional gas chromatography coupled to time-of-flight mass spectrometry.

    PubMed

    Avila, Bárbara M F; Pereira, Ricardo; Gomes, Alexandre O; Azevedo, Débora A

    2011-05-27

    Comprehensive two-dimensional gas chromatography coupled to time-of-flight mass spectrometry (GC×GC-TOFMS) was used for the characterization of aromatic compounds present in extra heavy gas oil (EHGO) from Brazil. Individual identification of EHGO compounds was successfully achieved in addition to group-type separation on the chromatographic plane. Many aromatic hydrocarbons, especially polycyclic aromatic hydrocarbons and sulfur compounds, were detected and identified, such as chrysenes, phenanthrenes, perylenes, benzonaphthothiophenes and alkylbenzonaphthothiophenes. In addition, triaromatic steroids, methyl-triaromatic steroids, tetrahydrochrysenes and tetraromatic pentacyclic compounds were present in the EHGO aromatic fractions. Considering the roof-tile effect observed for many of these compound classes and the high number of individual compounds identified, GC×GC-TOFMS is an excellent technique to characterize the molecular composition of the aromatic fraction from EHGO samples. Moreover, data processing allowed the quantification of aromatic compounds, in class and individually, using external standards. EHGO data were obtained in μgg(-1), e.g., benzo[a]pyrene were in the range 351 to 1164μgg(-1). Thus, GC×GC-TOFMS was successfully applied in EHGO quantitative analysis. PMID:20934179

  6. [Methanogenic destruction of (amino)aromatic compounds by anaerobic microbial communities].

    PubMed

    Lin'kova, Iu V; D'iakonova, A T; Gladchenko, M A; Kaliuzhnyĭ, S A; Kotova, I B; Stams, A; Netrusov, A I

    2011-01-01

    Destruction of a number of aromatic substrates by anaerobic microbial communities was studied. Active methanogenic microbial communities decomposing aminoaromatic acids and azo dyes into CH4 and CO2 were isolated. Products of primary conversion were found to be 2-hydroxybenzyl and benzyl alcohols gradually transforming into benzoate. It was shown that isolated microbial communities are capable of converting the initial substrates--benzyl alcohol, benzoate, salicylic acid, and golden yellow azo dye--into biogas without a lag-phase but with different velocities. Aromatic and linear intermediates of biodestruction of aromatic amines by obtained enrichment cultures were determined for the first time. Selective effect of aromatic substrates on a microbial community that was expressed in decrease in diversity and gradual change of dominant morphotypes was revealed. PMID:22232897

  7. EVALUATION OF SAMPLING AND ANALYTICAL METHODOLOGY FOR POLYNUCLEAR AROMATIC COMPOUNDS IN INDOOR AIR

    EPA Science Inventory

    The objective of this project was to develop a generic sampling and analytical methodology to characterize the polynuclear aromatic hydrocarbon (PAH) concentrations in air within various microenvironments. The following three studies were performed: evaluation of analytical metho...

  8. PHOTOACTIVATION AND TOXICITY OF MIXTURES OF POLYCYCLIC AROMATIC HYDROCARBON COMPOUNDS IN MARINE SEDIMENT

    EPA Science Inventory

    The direct toxicity and photoinduced toxicity of sediment-associated acenaphthene, phenanthrene, fluoranthene, and pyrene were determined for the marine amphipod Rhepoxynius abronius. The four polycyclic aromatic hydrocarbons (PAHs) were spiked into sediment in a concentration se...

  9. Exciting fluorescence compounds on an optical fiber's side surface with a liquid core waveguide.

    PubMed

    Ray, Jason C; Almas, Muhammad S; Tao, Shiquan

    2016-01-01

    A new fiber optic fluorescence spectroscopic method using a liquid core waveguide (LCW) as an excitation element has been developed for detecting a fluorescence compound absorbed on an optical fiber's surface. A laser light beam was coupled into a multimode optical fiber. The distal end of the fiber was inserted into an LCW. The diverging light emerging from the fiber's end was collected and guided within the LCW. A tapered optical fiber was inserted into the LCW from the other side. Laser light traveling in the LCW evenly illuminates the tapered fiber surface and excites fluorescence molecules absorbed on the tapered fiber's surface. Fluorescence light emitted from the tapered fiber surface was collected with the fiber itself and delivered through the fiber to an optical fiber compatible spectrometer for detection. This new technique provides an efficient way for evenly exciting fluorescence compounds absorbed on an optical fiber's surface. PMID:26696168

  10. Determination of the aromatic compounds in plant cuticular waxes using FT-IR spectroscopy

    NASA Astrophysics Data System (ADS)

    Dubis, Eligiusz N.; Dubis, Alina T.; Popławski, J.

    2001-09-01

    The infrared study of the aromatic components of hops ( Humulus lupulus) cuticular wax was performed. HATR FT-IR technique for fresh leaves and their extract analysis was applied. Phenylmethyl myristate, 2-phenylethyl myristate and docosyl benzoate were synthesized and used as reference standards. An absorption band in the range of 709-966 cm -1 indicates the presence of aromatic esters in plant cuticular waxes.

  11. Quantification of polycyclic aromatic hydrocarbons in water: a comparative study based on three-dimensional excitation-emission matrix fluorescence.

    PubMed

    Wang, Huanbo; Zhang, Yujun; Xiao, Xue

    2010-01-01

    Excitation-emission matrix fluorescence (EEM) was proposed to quantify three polycyclic aromatic hydrocarbons of anthracene (AN), phenanthrene (PHE) and pyrene (PY) in this paper. Direct analysis through selecting the appropriate areas from the data of EEMs and another approach using all data of EEM combined with the Parallel Factor (PARAFAC) were discussed respectively. The results showed that the predicted concentrations of PHE and PY approached the actual one for both methodologies, and that the room-mean-square errors of the prediction were no more than 0.5 µg L(-1). In addition, a new quantificational method was suggested, in which the sum intensity around the peak value replaced the maximum intensity in the selected regions. The sensitivity can be improved ten times compared with the conventional analysis. PMID:21157096

  12. Solid-matrix fluorescence and phosphorescence and solid-phase microextraction of polycyclic aromatic hydrocarbons with hydrophobic paper

    SciTech Connect

    Ackerman, A.H.; Hurtubise, R.J.

    1999-07-01

    Solid-matrix fluorescence (SMF) and solid-matrix phosphorescence (SMP) have been used in conjunction with solid-phase microextraction to characterize mixtures of polycyclic aromatic hydrocarbons (PAHs) isolated from water. Whatman 1PS paper was used to extract the PAH from water, and then the isolated PAHs were directly identified on the paper by obtaining SMF and SMP spectra. The SMF and SMP properties of 10 PAH were obtained, and the PAHs in a two-component mixture, a three-component mixture, and a four-component mixture were easily identified by a combination of SMF and SMP. No external heavy atom was needed to acquire the SMP data. Benzo[{ital e}]pyrene gave a limit of detection of 6.2 pg/mL with SMP, and with SMF benzo[{ital a}]pyrene gave a limit of detection of 19 pg/mL. {copyright} {ital 1999} {ital Society for Applied Spectroscopy}

  13. Thermodynamics of the hydrogen bonding of nitrogen-containing cyclic and aromatic compounds with proton donors: The structure-property relationship

    NASA Astrophysics Data System (ADS)

    Rakipov, I. T.; Varfolomeev, M. A.; Kirgizov, A. Yu.; Solomonov, B. N.

    2014-12-01

    Enthalpies of dissolution are measured at infinite dilution of nitrogen-containing cyclic (pyrrolidine, piperidine) and aromatic compounds (aniline, N-methylaniline, N,N-dimethylaniline, N-methylimidazole, pyridine, 2-, 3-, 4-methylpyridine, pyrrole, N-methylpyrrole) in chloroform and dichloromethane, and vice versa ( T = 298.15 K). The enthalpies of hydrogen bonds in the above systems are calculated. Relationships between resulting thermochemical data and the structure of nitrogen-containing cyclic and aromatic compounds are explored.

  14. Measurement of diffusion of fluorescent compounds and autofluorescence in skin in vivo using a confocal instrument

    NASA Astrophysics Data System (ADS)

    Buttenschoen, K. K.; Sutton, E. E.; Daly, D.; Girkin, J. M.

    2016-02-01

    Using compact and affordable instrumentation based upon fluorescent confocal imaging we have tracked the movement of autofluorescent compounds through skin in near real time with high temporal and spatial resolution and sensitivity. The ability to measure the diffusion of compounds through skin with such resolution plays an important role for applications such as monitoring the penetration of pharmaceuticals applied to skin and assessing the integrity of the skin barrier. Several measurement methods exist, but they suffer from a number of problems such as being slow, expensive, non-portable and lacking sensitivity. To address these issues, we adapted a technique that we previously developed for tracking fluorescent compounds in the eye to measure the autofluorescence and the diffusion of externally applied fluorescent compounds in skin in vivo. Results are presented that show the change in autofluorescence of the volar forearm over the course of a week. We furthermore demonstrate the ability of the instrument to measure the diffusion speed and depth of externally applied fluorescent compounds both in healthy skin and after the skin barrier function has been perturbed. The instrument is currently being developed further for increased sensitivity and multi-wavelength excitation. We believe that the presented instrument is suitable for a large number of applications in fields such as assessment of damage to the skin barrier, development of topical and systemic medication and tracking the diffusion of fluorescent compounds through skin constructs as well as monitoring effects of skin products and general consumer products which may come into contact with the skin.

  15. Scavenging ratio of polycyclic aromatic compounds in rain and snow at the Athabasca oil sands region

    NASA Astrophysics Data System (ADS)

    Zhang, L.; Cheng, I.; Muir, D.; Charland, J.-P.

    2014-07-01

    Athabasca oil sands industry in northern Alberta, Canada is a possible source of polycyclic aromatic compounds (PACs). Monitored PACs, including polycyclic aromatic hydrocarbons (PAHs), alkylated PAHs, and dibenzothiophenes, in precipitation and in air at three near-source sites in the Fort MacKay and Fort McMurray area during May 2011 to August 2012 were analyzed to generate a database of scavenging (or washout) ratios (Wt) for PACs scavenged by both snow and rain. Median precipitation and air concentrations of parent PAHs over the May 2011 to August 2012 period ranged from 0.3-184.9 (chrysene) ng L-1 and 0.01-3.9 (naphthalene) ng m-3, respectively, which were comparable to literature values. Higher concentrations in precipitation and air were observed for alkylated PAHs and dibenzothiophenes. The median precipitation and air concentrations were 11.3-646.7 (C3-fluoranthene/pyrene) ng L-1 and 0.21-16.9 (C3-naphthalene) ng m-3, respectively, for alkylated PAHs, and 8.5-530.5 (C4-dibenzothiophene) ng L-1 and 0.13-6.6 (C2-dibenzothiophene) ng m-3 for dibenzothiophenes and their alkylated derivatives. Median Wt over the measurement period were 6100-1.1 × 106 from snow scavenging and 350-2.3 × 105 from rain scavenging depending on the PAC species. Median Wt for parent PAHs were within the range of those observed at other urban and suburban locations. But Wt for acenaphthylene in snow samples was 2-7 times higher. Some individual snow and rain samples exceeded literature values by a factor of 10. Wt for benzo(a)pyrene, dibenz(a,h)anthracene, and benzo(g,h,i)perylene in snow samples had reached 107, which is the maximum for PAH snow scavenging ratios reported in literature. From the analysis of data subsets, Wt for particulate-phase dominant PACs were 14-20 times greater than gas-phase dominant PACs in snow samples and 7-20 times greater than gas-phase dominant PACs in rain samples. Wt from snow scavenging was ∼9 times greater than rain scavenging for particulate

  16. Scavenging ratios of polycyclic aromatic compounds in rain and snow in the Athabasca oil sands region

    NASA Astrophysics Data System (ADS)

    Zhang, L.; Cheng, I.; Muir, D.; Charland, J.-P.

    2015-02-01

    The Athabasca oil sands industry in northern Alberta, Canada, is a possible source of polycyclic aromatic compounds (PACs). Monitored PACs, including polycyclic aromatic hydrocarbons (PAHs), alkylated PAHs, and dibenzothiophenes (DBTs), in precipitation and in air at three near-source sites in the Fort MacKay and Fort McMurray area during January 2011 to May 2012, were used to generate a database of scavenging ratios (Wt) for PACs scavenged by both snow and rain. Higher concentrations in precipitation and air were observed for alkylated PAHs and DBTs compared to the other PACs. The sums of the median precipitation concentrations over the period of data analyzed were 0.48 μ g L-1 for the 18 PAHs, 3.38 μ g L-1 for the 20 alkylated PAHs, and 0.94 μ g L-1 for the 5 DBTs. The sums of the median air concentrations for parent PAHs, alkylated PAHs, and DBTs were 8.37, 67.26, and 11.83 ng m-3, respectively. Median Wt over the measurement period were 6100 - 1.1 × 106 from snow scavenging and 350 - 2.3 × 105 from rain scavenging depending on the PAC species. Median Wt for parent PAHs were within the range of those observed at other urban and suburban locations, but Wt for acenaphthylene in snow samples were 2-7 times higher compared to other urban and suburban locations. Wt for some individual snow and rain samples exceeded literature values by a factor of 10. Wt for benzo(a)pyrene, dibenz(a,h)anthracene, and benzo(g,h,i)perylene in snow samples had reached 107, which is the maximum for PAH snow scavenging ratios reported in the literature. From the analysis of data subsets, Wt for particulate-phase dominant PACs were 14-20 times greater than gas-phase dominant PACs in snow samples and 7-20 times greater than gas-phase dominant PACs in rain samples. Wt from snow scavenging were ~ 9 times greater than from rain scavenging for particulate-phase dominant PACs and 4-9.6 times greater than from rain scavenging for gas-phase dominant PACs. Gas-particle fractions of each PAC

  17. Effect of counter ions of arginine as an additive for the solubilization of protein and aromatic compounds.

    PubMed

    Yoshizawa, Shunsuke; Arakawa, Tsutomu; Shiraki, Kentaro

    2016-10-01

    Arginine is widely used in biotechnological application, but mostly with chloride counter ion. Here, we examined the effects of various anions on solubilization of aromatic compounds and reduced lysozyme and on refolding of the lysozyme. All arginine salts tested increased the solubility of propyl gallate with acetate much more effectively than chloride. The effects of arginine salts were compared with those of sodium or guanidine salts, indicating that the ability of anions to modulate the propyl gallate solubility is independent of the cation. Comparison of transfer free energy of propyl gallate between sodium and arginine salts indicates that the interaction of propyl gallate is more favorable with arginine than sodium. On the contrary, the solubility of aromatic amino acids is only slightly modulated by anions, implying that there is specific interaction between acetic acid and propyl gallate. Unlike their effects on the solubility of small aromatic compounds, the solubility of reduced lysozyme was much higher in arginine chloride than in arginine acetate or sulfate. Consistent with high solubility, refolding of reduced lysozyme was most effective in arginine chloride. These results suggest potential broader applications of arginine modulated by different anions. PMID:27234496

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

    PubMed

    Tang, Pei-Ling; Hassan, Osman; Maskat, Mohamad Yusof; Badri, Khairiah

    2015-01-01

    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. PMID:26798644

  19. Long wave fluorophore sensor compounds and other fluorescent sensor compounds in polymers

    DOEpatents

    Walsh, Joseph C.; Heiss, Aaron M.; Noronha, Glenn; Vachon, David J.; Lane, Stephen M.; Satcher, Jr., Joe H.; Peyser, Thomas A.; Van Antwerp, William Peter; Mastrototaro, John Joseph

    2004-07-20

    Fluorescent biosensor molecules, fluorescent biosensors and systems, as well as methods of making and using these biosensor molecules and systems are described. Embodiments of these biosensor molecules exhibit fluorescence emission at wavelengths greater than about 650 nm. Typical biosensor molecules include a fluorophore that includes an iminium ion, a linker moiety that includes a group that is an anilinic type of relationship to the fluorophore and a boronate substrate recognition/binding moiety, which binds glucose. The fluorescence molecules modulated by the presence or absence of polyhydroxylated analytes such as glucose. This property of these molecules of the invention, as well as their ability to emit fluorescent light at greater than about 650 nm, renders these biosensor molecules particularly well-suited for detecting and measuring in-vivo glucose concentrations.

  20. Chemometrics-assisted excitation-emission fluorescence spectroscopy on nylon-attached rotating disks. Simultaneous determination of polycyclic aromatic hydrocarbons in the presence of interferences.

    PubMed

    Cañas, Alejandro; Richter, Pablo; Escandar, Graciela M

    2014-12-10

    This work presents a green and very simple approach which enables the accurate and simultaneous determination of benzo[a]pyrene, dibenz[a,h]anthracene, benz[a]anthracene, and chrysene, concerned and potentially carcinogenic heavy-polycyclic aromatic hydrocarbons (PAHs) in interfering samples. The compounds are extracted from water samples onto a device composed of a small rotating Teflon disk, with a nylon membrane attached to one of its surfaces. After extraction, the nylon membrane containing the concentrated analytes is separated from the Teflon disk, and fluorescence excitation-emission matrices are directly measured on the nylon surface, and processed by applying parallel factor analysis (PARAFAC), without the necessity of a desorption step. Under optimum conditions and for a sample volume of 25 mL, the PAHs extraction was carried out in 20 min. Detection limits based on the IUPAC recommended criterion and relative errors of prediction were in the ranges 20-100 ng L(-1) and 5-7%, respectively. Thanks to the combination of the ability of nylon to strongly retain PAHs, the easy rotating disk extraction approach, and the selectivity of second-order calibration, which greatly simplifies sample treatment avoiding the use of toxic solvents, the developed method follows most green analytical chemistry principles. PMID:25441886

  1. A time-temperature integrator based on fluorescent and polymorphic compounds

    PubMed Central

    Gentili, Denis; Durso, Margherita; Bettini, Cristian; Manet, Ilse; Gazzano, Massimo; Capelli, Raffaella; Muccini, Michele; Melucci, Manuela; Cavallini, Massimiliano

    2013-01-01

    Despite the variety of functional properties of molecular materials, which make them of interest for a number of technologies, their tendency to form inhomogeneous aggregates in thin films and to self-organize in polymorphs are considered drawbacks for practical applications. Here, we report on the use of polymorphic molecular fluorescent thin films as time temperature integrators, a class of devices that monitor the thermal history of a product. The device is fabricated by patterning the fluorescent model compound thieno(bis)imide-oligothiophene. The fluorescence colour of the pattern changes as a consequence of an irreversible phase variation driven by temperature, and reveals the temperature at which the pattern was exposed. The experimental results are quantitatively analysed in the range 20–200°C and interpreted considering a polymorph recrystallization in the thin film. Noteworthy, the reported method is of general validity and can be extended to every compound featuring irreversible temperature-dependent change of fluorescence. PMID:24002421

  2. [Fluorescence enhancement character of terbium perchlorate and thulium perchlorate with phenylcarboxymethyl sulfoxide coordination compounds].

    PubMed

    Li, Wen-xian; Wu, Guo-jiun; Liu, Zhong-shi; Han, Feng-mei

    2002-12-01

    (Tb1-x Tmx).L2.(ClO4).2H2O(x = 0.000 to 0.200, L = C6H5SOCH2COO-) have been synthesized. The coordination compounds have been studied by means of composition analysis, molar conductivity, IR, and the condition of coordination have been inferred. In the fluorescent spectra it was found that Tm3+ has a strongly sensitization effect to the fluorescence of Tb3+. The fluorescent emission intensity of Terbium perchlorate with phenylcarboxymethyl sulfoxide coordination compounds would be enhanced by Tm3+ in mixing. Tm3+ has a sensitization to the fluorescence of Tb3+ in the ratio of Tb3+:Tm3+ = 0.999:0.001-0.900:0.100. In the solubility experiment it was found that the complexes have high solubility in ethanol. PMID:12914160

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

    PubMed

    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

  4. Generalizing the Concept of Specific Compound Formulation Additives towards Non-Fluorescent Drugs: A Solubilization Study on Potential Anti-Alzheimer-Active Small-Molecule Compounds.

    PubMed

    Lawatscheck, Carmen; Pickhardt, Marcus; Wieczorek, Sebastian; Grafmüller, Andrea; Mandelkow, Eckhard; Börner, Hans G

    2016-07-18

    Tailor-made compound formulation additives enable the testing of potential drugs with undesirable pharmacological profiles. A combinatorial approach using Raman microscopy as the readout method is presented to select peptide sequences from large one-bead-one-compound libraries. The resulting peptide-PEG conjugates solubilize potential prophylactic and therapeutic anti-Alzheimer compounds and can be used as specific additives not only for fluorescent but also for non-fluorescent compounds. PMID:27282127

  5. SiRNAs conjugated with aromatic compounds induce RISC-mediated antisense strand selection and strong gene-silencing activity

    SciTech Connect

    Kubo, Takanori; Yanagihara, Kazuyoshi; Takei, Yoshifumi; Mihara, Keichiro; Sato, Yuichiro; Seyama, Toshio

    2012-10-05

    Highlights: Black-Right-Pointing-Pointer SiRNAs conjugated with aromatic compounds (Ar-siRNAs) at 5 Prime -sense strand were synthesized. Black-Right-Pointing-Pointer Ar-siRNAs increased resistance against nuclease degradation. Black-Right-Pointing-Pointer Ar-siRNAs were thermodynamically stable compared with the unmodified siRNA. Black-Right-Pointing-Pointer High levels of cellular uptake and cytoplasmic localization were found. Black-Right-Pointing-Pointer Strong gene-silencing efficacy was exhibited in the Ar-siRNAs. -- Abstract: Short interference RNA (siRNA) is a powerful tool for suppressing gene expression in mammalian cells. In this study, we focused on the development of siRNAs conjugated with aromatic compounds in order to improve the potency of RNAi and thus to overcome several problems with siRNAs, such as cellular delivery and nuclease stability. The siRNAs conjugated with phenyl, hydroxyphenyl, naphthyl, and pyrenyl derivatives showed strong resistance to nuclease degradation, and were thermodynamically stable compared with unmodified siRNA. A high level of membrane permeability in HeLa cells was also observed. Moreover, these siRNAs exhibited enhanced RNAi efficacy, which exceeded that of locked nucleic acid (LNA)-modified siRNAs, against exogenous Renilla luciferase in HeLa cells. In particular, abundant cytoplasmic localization and strong gene-silencing efficacy were found in the siRNAs conjugated with phenyl and hydroxyphenyl derivatives. The novel siRNAs conjugated with aromatic compounds are promising candidates for a new generation of modified siRNAs that can solve many of the problems associated with RNAi technology.

  6. Comparative study of aromatic compounds in fruit wines from raspberry, strawberry, and mulberry in central Shaanxi area

    PubMed Central

    Feng, Yiming; Liu, Min; Ouyang, Yanan; Zhao, Xianfang; Ju, Yanlun; Fang, Yulin

    2015-01-01

    Background Although grape wines have firmly dominated the production and consumption markets of fruit wines, raspberry, strawberry, and mulberry have been utilized to make wines because of their joyful aroma and high contents of polyphenolic phytochemicals and essential fatty acids. However, little is known about aromatic compounds of the wines produced from these three fruits. Methods The aromatic composition of fruit wines produced from raspberry, strawberry, mulberry, and red grape was analyzed by GC-MS. Odor activity values (OAVs) and relative odor contributions (ROCs) were used to estimate the sensory contribution of the aromatic compounds to the overall flavor of the wines. Results In strawberry, raspberry, and mulberry wines, 27, 30, and 31 odorants were detected, respectively. Alcohols formed the most abundant group, followed by esters and acids. The grape wine contained a wider variety (16 types) of alcohols, and 4-methyl-2-pentanol and 2,3-butanediol were not present in the three fruit wines. The quantity of esters in raspberry (1.54%) and mulberry wines (2.08%) were higher than those of strawberry wine (0.78%), and mulberry wine contained more types of esters. There were no significant differences of acids between the three fruit wines and the control wine. In addition, 2-heptanone, 2-octanone, 2-nonanone, and 2-undecanone were unique to raspberry wine, and nonanal was present only in mulberry wine. The indistinguishable aroma of the three fruit wines was attributed to the dominance of fruity and floral odor components derived from ethyl esters of fatty acids and their contributions to the global aroma of the three fruit wines. Conclusion The present study demonstrated that there were significant differences in the volatile components of fruit wines made from raspberry, strawberry, and mulberry. The aroma compounds were more abundant in the raspberry and mulberry wines than in the strawberry wine, but the quality of strawberry wine was superior to

  7. Upconversion fluorescence resonance energy transfer biosensor with aromatic polymer nanospheres as the lable-free energy acceptor.

    PubMed

    Wang, Yuhui; Wu, Zhengjun; Liu, Zhihong

    2013-01-01

    We report a new upconversion fluorescence resonance energy transfer (UC-FRET) biosensor using poly-m-phenylenediamine (PMPD) nanospheres as the energy acceptor in this paper. A single-stranded DNA (ssDNA) tagged with a sulfydryl group at the 5'-terminus was covalently linked to poly(ethylenimine) (PEI) functionalized upconversion phosphors (UCPs, the energy donor). Because of the π-rich electronic structure of PMPD, self-assembly of the donor and the acceptor was achieved through the π-π stacking interaction between ssDNA and PMPD. The fluorescence of the donor was quenched by the acceptor in a PMPD-concentration-dependent manner. A maximum quenching degree of 90% was acquired, which was among the highest levels of all previous reports. Upon the formation of double-stranded DNA (dsDNA) between the target DNA and the probe DNA, the energy acceptor was separated from the donor due to the weakened interaction between dsDNA and PMPD. The fluorescence of UCPs was accordingly restored, and a linear response was obtained with the target concentration ranging from 0.1 to 6.0 nM. The limit of detection was calculated as 0.036 nM, which was a highly competitive sensitivity. The sensor also showed high precision, pronounced specificity, and the applicability to complicated sample matrix (human serum). The UCPs-PMPD FRET sensing platform takes advantages of both the optical merits of the upconversion donors and the superquenching ability and good water-solubility of the aromatic polymer nanoparticles. This study will open the opportunity to develop a new class of UC-FRET biosensors. PMID:23186324

  8. Immunological disorders associated with polychlorinated biphenyls and related halogenated aromatic hydrocarbon compounds

    USGS Publications Warehouse

    Noguchi, G.E.

    1998-01-01

    This review characterizes immunological disorders in fish associated with the widespread environmental contaminants, polychlorinated biphenyls (PCBs), and related halogenated aromatic hydrocarbons (HAHs). Special attention is devoted to comparing the sensitivity of fish species, identifying sensitive immunological endpoints and postulating mechanisms of action.

  9. Dehydrogenative Coupling Reactions with Oxidized Guanidino-Functionalized Aromatic Compounds: Novel Options for σ-Bond Activation.

    PubMed

    Wild, Ute; Federle, Stefanie; Wagner, Arne; Kaifer, Elisabeth; Himmel, Hans-Jörg

    2016-08-16

    We present a new option for metal-free σ-bond activation, making use of oxidized, guanidino-functionalized aromatic compounds (GFAs). We demonstrate this new option by the homocoupling reactions of thiols and phosphines. The kinetics and the reaction pathway were studied by a number of experiments (including heterocoupling of thiols and phosphines), supported by quantum-chemical computations. Reaction of the oxidized GFA with p-dihydrobenzoquinone to give p-benzoquinone shows that typical proton-coupled electron-transfer reactions are also possible. PMID:27430589

  10. Cyclic four-coordinate boron compounds from 5-amino-1,2,4-triazole and aromatic nitriles

    SciTech Connect

    Dorokhov, V.A.; Amamchyan, A.R.; Bochkareva, M.N.; Teslya, I.A.; Starikova, Z.A.

    1987-07-20

    A new series of cyclic compounds of four coordinate boron- the dialkylboryl-((1,2,4-triazol-5-yl)amidinates) (IX)- has been synthesized from 5-amino-1,2,4-triazole, aromatic nitriles, and trialkylboranes. In the crystalline, dimeric dialkylboryl derivatives of 5-amino-1,2,4-triazole the Alk/sub 2/B groups are bonded to the ring N atoms. The crystalline and molecular structure of dipropylboryl((1,2,4-triazol-5-yl)benzamidinate) (IXa) have been determined by X-ray crystallography.

  11. Use of Time-Resolved Fluorescence to Monitor Bioactive Compounds in Plant Based Foodstuffs

    PubMed Central

    Lemos, M. Adília; Sárniková, Katarína; Bot, Francesca; Anese, Monica; Hungerford, Graham

    2015-01-01

    The study of compounds that exhibit antioxidant activity has recently received much interest in the food industry because of their potential health benefits. Most of these compounds are plant based, such as polyphenolics and carotenoids, and there is a need to monitor them from the field through processing and into the body. Ideally, a monitoring technique should be non-invasive with the potential for remote capabilities. The application of the phenomenon of fluorescence has proved to be well suited, as many plant associated compounds exhibit fluorescence. The photophysical behaviour of fluorescent molecules is also highly dependent on their microenvironment, making them suitable probes to monitor changes in pH, viscosity and polarity, for example. Time-resolved fluorescence techniques have recently come to the fore, as they offer the ability to obtain more information, coupled with the fact that the fluorescence lifetime is an absolute measure, while steady state just provides relative and average information. In this work, we will present illustrative time-resolved measurements, rather than a comprehensive review, to show the potential of time-resolved fluorescence applied to the study of bioactive substances. The aim is to help assess if any changes occur in their form, going from extraction via storage and cooking to the interaction with serum albumin, a principal blood transport protein. PMID:26132136

  12. Use of Time-Resolved Fluorescence to Monitor Bioactive Compounds in Plant Based Foodstuffs.

    PubMed

    Lemos, M Adília; Sárniková, Katarína; Bot, Francesca; Anese, Monica; Hungerford, Graham

    2015-01-01

    The study of compounds that exhibit antioxidant activity has recently received much interest in the food industry because of their potential health benefits. Most of these compounds are plant based, such as polyphenolics and carotenoids, and there is a need to monitor them from the field through processing and into the body. Ideally, a monitoring technique should be non-invasive with the potential for remote capabilities. The application of the phenomenon of fluorescence has proved to be well suited, as many plant associated compounds exhibit fluorescence. The photophysical behaviour of fluorescent molecules is also highly dependent on their microenvironment, making them suitable probes to monitor changes in pH, viscosity and polarity, for example. Time-resolved fluorescence techniques have recently come to the fore, as they offer the ability to obtain more information, coupled with the fact that the fluorescence lifetime is an absolute measure, while steady state just provides relative and average information. In this work, we will present illustrative time-resolved measurements, rather than a comprehensive review, to show the potential of time-resolved fluorescence applied to the study of bioactive substances. The aim is to help assess if any changes occur in their form, going from extraction via storage and cooking to the interaction with serum albumin, a principal blood transport protein. PMID:26132136

  13. Dual-emitting nanocomposites derived from rare-earth compound nanotubes for ratiometric fluorescence sensing applications.

    PubMed

    Sun, Tian-Ying; Zhang, Da-Quan; Yu, Xue-Feng; Xiang, Yang; Luo, Min; Wang, Jia-Hong; Tan, Guo-Long; Wang, Qu-Quan; Chu, Paul K

    2013-02-21

    A new class of ratiometric fluorescence sensors composed of rare-earth (RE) compound nanotubes is described. Polyethylenimine-coated yttrium hydroxide fluoride nanotubes (YHF NTs) that were synthesized hydrothermally exhibit highly efficient fluorescence when doped with RE ions. The polyethylenimine on the NTs facilitates the incorporation of phosphors such as quantum dots or organic dyes onto the NT surface to produce dual-emitting nanocomposites which are excellent ratiometric fluorescence sensors. The phosphor layer and underlying tubes in the nanocomposites act as the indicator and reference probes, respectively. This ratiometric fluorescence method which can be applied to the detection of heavy metals in solutions, temperature sensing, and pH sensing boasts high sensitivity and selectivity as well as better accuracy than traditional intensity-based fluorescence methods. PMID:23334204

  14. Dual-emitting nanocomposites derived from rare-earth compound nanotubes for ratiometric fluorescence sensing applications

    NASA Astrophysics Data System (ADS)

    Sun, Tian-Ying; Zhang, Da-Quan; Yu, Xue-Feng; Xiang, Yang; Luo, Min; Wang, Jia-Hong; Tan, Guo-Long; Wang, Qu-Quan; Chu, Paul K.

    2013-01-01

    A new class of ratiometric fluorescence sensors composed of rare-earth (RE) compound nanotubes is described. Polyethylenimine-coated yttrium hydroxide fluoride nanotubes (YHF NTs) that were synthesized hydrothermally exhibit highly efficient fluorescence when doped with RE ions. The polyethylenimine on the NTs facilitates the incorporation of phosphors such as quantum dots or organic dyes onto the NT surface to produce dual-emitting nanocomposites which are excellent ratiometric fluorescence sensors. The phosphor layer and underlying tubes in the nanocomposites act as the indicator and reference probes, respectively. This ratiometric fluorescence method which can be applied to the detection of heavy metals in solutions, temperature sensing, and pH sensing boasts high sensitivity and selectivity as well as better accuracy than traditional intensity-based fluorescence methods.A new class of ratiometric fluorescence sensors composed of rare-earth (RE) compound nanotubes is described. Polyethylenimine-coated yttrium hydroxide fluoride nanotubes (YHF NTs) that were synthesized hydrothermally exhibit highly efficient fluorescence when doped with RE ions. The polyethylenimine on the NTs facilitates the incorporation of phosphors such as quantum dots or organic dyes onto the NT surface to produce dual-emitting nanocomposites which are excellent ratiometric fluorescence sensors. The phosphor layer and underlying tubes in the nanocomposites act as the indicator and reference probes, respectively. This ratiometric fluorescence method which can be applied to the detection of heavy metals in solutions, temperature sensing, and pH sensing boasts high sensitivity and selectivity as well as better accuracy than traditional intensity-based fluorescence methods. Electronic supplementary information (ESI) available: EA and TGA profiles, emission spectra of YHF:Eu NTs. See DOI: 10.1039/c2nr33217e

  15. Participation of Electron Transfer Process in Rate-Limiting Step of Aromatic Hydroxylation Reactions by Compound I Models of Heme Enzymes.

    PubMed

    Asaka, Maaya; Fujii, Hiroshi

    2016-07-01

    Hydroxylation reactions of aromatic rings are key reactions in various biological and chemical processes. In spite of their significance, no consensus mechanism has been established. Here we performed Marcus plot analysis for aromatic hydroxylation reactions with oxoiron(IV) porphyrin π-cation radical complexes (compound I). Although many recent studies support the mechanism involving direct electrophilic attack of compound I, the slopes of the Marcus plots indicate a significant contribution of an electron transfer process in the rate-limiting step, leading us to propose a new reaction mechanism in which the electron transfer process between an aromatic compound and compound I is in equilibrium in a solvent cage and coupled with the subsequent bond formation process. PMID:27327623

  16. Mineral dust aerosols promote the formation of toxic nitropolycyclic aromatic compounds

    PubMed Central

    Kameda, Takayuki; Azumi, Eri; Fukushima, Aki; Tang, Ning; Matsuki, Atsushi; Kamiya, Yuta; Toriba, Akira; Hayakawa, Kazuichi

    2016-01-01

    Atmospheric nitrated polycyclic aromatic hydrocarbons (NPAHs), which have been shown to have adverse health effects such as carcinogenicity, are formed in part through nitration reactions of their parent polycyclic aromatic hydrocarbons (PAHs) in the atmosphere. However, little is known about heterogeneous nitration rates of PAHs by gaseous NO2 on natural mineral substrates, such as desert dust aerosols. Herein by employing kinetic experiments using a flow reactor and surface analysis by Fourier transform infrared spectroscopy with pyridine adsorption, we demonstrate that the reaction is accelerated on acidic surfaces of mineral dust, particularly on those of clay minerals. In support of this finding, we show that levels of ambient particle-associated NPAHs in Beijing, China, significantly increased during heavy dust storms. These results suggest that mineral dust surface reactions are an unrecognized source of toxic organic chemicals in the atmosphere and that they enhance the toxicity of mineral dust aerosols in urban environments. PMID:27075250

  17. Mineral dust aerosols promote the formation of toxic nitropolycyclic aromatic compounds.

    PubMed

    Kameda, Takayuki; Azumi, Eri; Fukushima, Aki; Tang, Ning; Matsuki, Atsushi; Kamiya, Yuta; Toriba, Akira; Hayakawa, Kazuichi

    2016-01-01

    Atmospheric nitrated polycyclic aromatic hydrocarbons (NPAHs), which have been shown to have adverse health effects such as carcinogenicity, are formed in part through nitration reactions of their parent polycyclic aromatic hydrocarbons (PAHs) in the atmosphere. However, little is known about heterogeneous nitration rates of PAHs by gaseous NO2 on natural mineral substrates, such as desert dust aerosols. Herein by employing kinetic experiments using a flow reactor and surface analysis by Fourier transform infrared spectroscopy with pyridine adsorption, we demonstrate that the reaction is accelerated on acidic surfaces of mineral dust, particularly on those of clay minerals. In support of this finding, we show that levels of ambient particle-associated NPAHs in Beijing, China, significantly increased during heavy dust storms. These results suggest that mineral dust surface reactions are an unrecognized source of toxic organic chemicals in the atmosphere and that they enhance the toxicity of mineral dust aerosols in urban environments. PMID:27075250

  18. Solubility of organic compounds in nonaqueous systems; Polycyclic aromatic hydrocarbons in benzene

    SciTech Connect

    Mishra, D.S.; Yalkowsky, S.H. )

    1990-11-01

    The present paper deals with the evaluation of some widely used models used to calculate activity coefficients and the assumptions for the ideal solubility for some polycyclic aromatic hydrocarbons in benzene. The results show that, for ideal solubility, {Delta}C{sub p} {approx} 0 is a better approximation than {Delta}C{sub p} {approx} {Delta}S{sub f}. The values obtained for the entropic activity coefficients are similar from both UNIFAC and Flory-Huggins theories. The residual activity coefficients calculated from Scatchard-Hildebrand theory and UNIFAC are, however, very different. The combination of Flory-Huggins and Scatchard-Hildebrand theories gives better predictions for the solubility of polycyclic aromatic hydrocarbons in benzene than does UNIFAC theory.

  19. Chemical characterization and mutagenic properties of polycyclic aromatic compounds in sediment from tributaries of the Great Lakes

    USGS Publications Warehouse

    Fabacher, David L.; Schmitt, Christopher J.; Besser, John M.; Mac, Michael J.

    1988-01-01

    Sediments from four inshore industrial sites and a reference site in the Great Lakes were extracted with solvents and characterized chemically for polycyclic aromatic compounds (PACs). An aqueous phase and a crude organic extract were obtained. The crude organic extract was further resolved into fractions A-2 (polycyclic aromatic hydrocarbons) and A-3 (nitrogen-containing polycyclic aromatic compounds), which were analyzed for PACs by gas chromatography and gas chromatography-mass spectrometry. The extracts and fractions were tested for mutagenicity in three assays: Ames, rat hepatocyte unscheduled DNA synthesis, and Chinese hamster ovary hypoxanthine-guanine phosphoribosyl transferase (CHO/HGPRT). Sediments from the industrial sites contained 27 to 363 μg/g total PACs; the reference site, less than 1 μg/g. Qualitative differences in the residue profiles among the sites were attributable to the probable sources of the PACs (petroleum versus combustion). Only one industrial site yielded measurable (0.1 μg/g or more) concentrations of individual nitrogen-containing PACs. In the Ames assay, only the highest doses of the A-2 fractions from two sites approached positive results. Conversely, the crude organic extract and A-2 and A-3 fractions from all sites induced unscheduled DNA synthesis. Crude organic extracts and the A-2 and A-3 fractions from all industrial sites gave well-defined dose-response relations in the CHO/HGPRT assay. We established the presence of chemical mutagens in sediment that could be correlated with neoplasms in fish from many of the sites; however, the mutagenicity of the sediment extracts was not completely related to the degree of contamination by PACs. We also discuss the utility of mutagenicity assays in the evaluation of complex chemical mixtures and recommend the use of a CHO/HGPRT-type assay in which cells are not required to proliferate in the presence of potential interfering chemicals.

  20. Aromatic sulfonyl fluorides covalently kinetically stabilize transthyretin to prevent amyloidogenesis while affording a fluorescent conjugate.

    PubMed

    Grimster, Neil P; Connelly, Stephen; Baranczak, Aleksandra; Dong, Jiajia; Krasnova, Larissa B; Sharpless, K Barry; Powers, Evan T; Wilson, Ian A; Kelly, Jeffery W

    2013-04-17

    Molecules that bind selectively to a given protein and then undergo a rapid chemoselective reaction to form a covalent conjugate have utility in drug development. Herein a library of 1,3,4-oxadiazoles substituted at the 2 position with an aryl sulfonyl fluoride and at the 5 position with a substituted aryl known to have high affinity for the inner thyroxine binding subsite of transthyretin (TTR) was conceived of by structure-based design principles and was chemically synthesized. When bound in the thyroxine binding site, most of the aryl sulfonyl fluorides react rapidly and chemoselectively with the pKa-perturbed K15 residue, kinetically stabilizing TTR and thus preventing amyloid fibril formation, known to cause polyneuropathy. Conjugation t50s range from 1 to 4 min, ~1400 times faster than the hydrolysis reaction outside the thyroxine binding site. X-ray crystallography confirms the anticipated binding orientation and sheds light on the sulfonyl fluoride activation leading to the sulfonamide linkage to TTR. A few of the aryl sulfonyl fluorides efficiently form conjugates with TTR in plasma. Eleven of the TTR covalent kinetic stabilizers synthesized exhibit fluorescence upon conjugation and therefore could have imaging applications as a consequence of the environment sensitive fluorescence of the chromophore. PMID:23350654

  1. Aromatic Sulfonyl Fluorides Covalently Kinetically Stabilize Transthyretin to Prevent Amyloidogenesis while Affording a Fluorescent Conjugate

    PubMed Central

    Grimster, Neil P.; Connelly, Stephen; Baranczak, Aleksandra; Dong, Jiajia; Krasnova, Larissa B.; Sharpless, K. Barry; Powers, Evan T.; Wilson, Ian A.; Kelly, Jeffery W.

    2013-01-01

    Molecules that bind selectively to a given protein and then undergo a rapid chemoselective reaction to form a covalent conjugate have utility in drug development. Herein a library of 1,3,4-oxadiazoles substituted at the 2 position with an aryl sulfonyl fluoride and at the 5 position with a substituted aryl known to have high affinity for the inner thyroxine binding subsite of transthyretin (TTR) were conceived of by structure-based design principles and were chemically synthesized. When bound in the thyroxine binding site, most of the aryl sulfonyl fluorides react rapidly and chemoselectively with the pKa-perturbed K15 residue, kinetically stabilizing TTR and thus preventing amyloid fibril formation, known to cause polyneuropathy. Conjugation t50s range from 1 to 4 min, ~ 1400 times faster than the hydrolysis reaction outside the thyroxine binding site. X-ray crystallography confirms the anticipated binding orientation and sheds light on the sulfonyl fluoride activation leading to the sulfonamide linkage to TTR. A few of the aryl sulfonyl fluorides efficiently form conjugates with TTR in plasma. A few of the TTR covalent kinetic stabilizers synthesized exhibit fluorescence upon conjugation and therefore could have imaging applications as a consequence of the environment sensitive fluorescence of the chromophore. PMID:23350654

  2. QSAR modeling of acute toxicity on mammals caused by aromatic compounds: the case study using oral LD50 for rats.

    PubMed

    Rasulev, Bakhtiyor; Kusić, Hrvoje; Leszczynska, Danuta; Leszczynski, Jerzy; Koprivanac, Natalija

    2010-05-01

    The goal of the study was to predict toxicity in vivo caused by aromatic compounds structured with a single benzene ring and the presence or absence of different substituent groups such as hydroxyl-, nitro-, amino-, methyl-, methoxy-, etc., by using QSAR/QSPR tools. A Genetic Algorithm and multiple regression analysis were applied to select the descriptors and to generate the correlation models. The most predictive model is shown to be the 3-variable model which also has a good ratio of the number of descriptors and their predictive ability to avoid overfitting. The main contributions to the toxicity were shown to be the polarizability weighted MATS2p and the number of certain groups C-026 descriptors. The GA-MLRA approach showed good results in this study, which allows the building of a simple, interpretable and transparent model that can be used for future studies of predicting toxicity of organic compounds to mammals. PMID:21491673

  3. pi-Selective stationary phases: (II) Adsorption behavior of substituted aromatic compounds on n-alkyl-phenyl stationary phases

    SciTech Connect

    Gritti, Fabrice; Guiochon, Georges A; Mayfield, Kirsty; Dennis, Gary; Shalliker, R. Andrew

    2010-01-01

    The frontal analysis method was used to measure the adsorption isotherms of phenol, 4-chlorophenol, p-cresol, 4-methoxyphenol and caffeine on a series of columns packed with home-made alkyl-phenyl bonded silica particles. These ligands consist of a phenyl ring tethered to the silica support via a carbon chain of length ranging from 0 to 4 atoms. The adsorption isotherm models that fit best to the data account for solute-solute interactions that are likely caused by p-p interactions occurring between aromatic compounds and the phenyl group of the ligand. These interactions are the dominant factor responsible for the separation of low molecular weight aromatic compounds on these phenyl-type stationary phases. The saturation capacities depend on whether the spacer of the ligands have an even or an odd number of carbon atoms, with the even alkyl chain lengths having a greater saturation capacity than the odd alkyl chain lengths. The trends in the adsorption equilibrium constant are also significantly different for the even and the odd chain length ligands.

  4. Laccase Production and Differential Transcription of Laccase Genes in Cerrena sp. in Response to Metal Ions, Aromatic Compounds, and Nutrients.

    PubMed

    Yang, Jie; Wang, Guozeng; Ng, Tzi Bun; Lin, Juan; Ye, Xiuyun

    2015-01-01

    Laccases can oxidize a wide range of aromatic compounds and are industrially valuable. Laccases often exist in gene families and may differ from each other in expression and function. Quantitative real-time polymerase chain reaction (qPCR) was used for transcription profiling of eight laccase genes in Cerrena sp. strain HYB07 with validated reference genes. A high laccase activity of 280.0 U/mL was obtained after submerged fermentation for 5 days. Laccase production and laccase gene transcription at different fermentation stages and in response to various environmental cues were revealed. HYB07 laccase activity correlated with transcription levels of its predominantly expressed laccase gene, Lac7. Cu(2+) ions were indispensable for efficient laccase production by HYB07, mainly through Lac7 transcription induction, and no aromatic compounds were needed. HYB07 laccase synthesis and biomass accumulation were highest with non-limiting carbon and nitrogen. Glycerol and inorganic nitrogen sources adversely impacted Lac7 transcription, laccase yields, and fungal growth. The present study would further our understanding of transcription regulation of laccase genes, which may in turn facilitate laccase production as well as elucidation of their physiological roles. PMID:26793186

  5. Laccase Production and Differential Transcription of Laccase Genes in Cerrena sp. in Response to Metal Ions, Aromatic Compounds, and Nutrients

    PubMed Central

    Yang, Jie; Wang, Guozeng; Ng, Tzi Bun; Lin, Juan; Ye, Xiuyun

    2016-01-01

    Laccases can oxidize a wide range of aromatic compounds and are industrially valuable. Laccases often exist in gene families and may differ from each other in expression and function. Quantitative real-time polymerase chain reaction (qPCR) was used for transcription profiling of eight laccase genes in Cerrena sp. strain HYB07 with validated reference genes. A high laccase activity of 280.0 U/mL was obtained after submerged fermentation for 5 days. Laccase production and laccase gene transcription at different fermentation stages and in response to various environmental cues were revealed. HYB07 laccase activity correlated with transcription levels of its predominantly expressed laccase gene, Lac7. Cu2+ ions were indispensable for efficient laccase production by HYB07, mainly through Lac7 transcription induction, and no aromatic compounds were needed. HYB07 laccase synthesis and biomass accumulation were highest with non-limiting carbon and nitrogen. Glycerol and inorganic nitrogen sources adversely impacted Lac7 transcription, laccase yields, and fungal growth. The present study would further our understanding of transcription regulation of laccase genes, which may in turn facilitate laccase production as well as elucidation of their physiological roles. PMID:26793186

  6. Ozonation of pyridine and other N-heterocyclic aromatic compounds: Kinetics, stoichiometry, identification of products and elucidation of pathways.

    PubMed

    Tekle-Röttering, Agnes; Reisz, Erika; Jewell, Kevin S; Lutze, Holger V; Ternes, Thomas A; Schmidt, Winfried; Schmidt, Torsten C

    2016-10-01

    Pyridine, pyridazine, pyrimidine and pyrazine were investigated in their reaction with ozone. These compounds are archetypes for heterocyclic aromatic amines, a structural unit that is often present in pharmaceuticals, pesticides and dyestuffs (e.g., enoxacin, pyrazineamide or pyrimethamine). The investigated target compounds react with ozone with rate constants ranging from 0.37 to 57 M(-1) s(-1), hampering their degradation during ozonation. In OH radical scavenged systems the reaction of ozone with pyridine and pyridazine is characterized by high transformation (per ozone consumed) of 55 and 54%, respectively. In non scavenged system the transformation drops to 52 and 12%, respectively. However, in the reaction of pyrimidine and pyrazine with ozone this is reversed. Here, in an OH radical scavenged system the compound transformation is much lower (2.1 and 14%, respectively) than in non scavenged one (22 and 25%, respectively). This is confirmed by corresponding high N-oxide formation in the ozonation of pyridine and pyridazine, but probably low formation in the reaction of pyrimidine and pyrazine with ozone. With respect to reaction mechanisms, it is suggested that ozone adduct formation at nitrogen is the primary step in the ozonation of pyridine and pyridazine. On the contrary, ozone adduct formation to the aromatic ring seems to occur especially in the ozonation of pyrimidine as inferred from hydrogen peroxide yield. However, also OH radical reactions are supposed processes in the case of pyrimidine and in particular for pyrazine, albeit negligible OH radical yields are obtained. The low compound transformation in OH radical scavenged system can prove this. As a result of negligible OH radical yields in all cases (less than 6%) electron transfer as primary reaction pathway plays a subordinate role. PMID:27448509

  7. Screening of edible oils for polycyclic aromatic hydrocarbons using microwave-assisted liquid-liquid and solid phase extraction coupled to one- to three-way fluorescence spectroscopy analysis.

    PubMed

    Alarcón, Francis; Báez, María E; Bravo, Manuel; Richter, Pablo; Fuentes, Edwar

    2012-10-15

    The potential of microwave-assisted liquid-liquid and solid phase extraction coupled with fluorescence spectroscopy and employing one- to three-way spectral data was assessed in terms of their capacity for the rapid detection of heavy polycyclic aromatic hydrocarbons (PAHs) in olive and sunflower oils. Tocopherols and pigments groups (chlorophyll and pheophytin) present in oil matrices were the main interference compounds in the detection of PAHs using fluorescence spectroscopy. Partial spectral overlap and inner-filter effects were observed in the emission range of the analytes. The effectiveness of removing these interferences using solid phase extraction (silica, C18 and graphitized carbon black) was examined. Solid phase extraction with silica was the most effective method for the removal of pigments and tocopherol and allowed for the detection of PAHs in edible oils using fluorescence spectroscopy. The limit of detection was observed to depend on the use of one-, two- or three-way fluorescence spectral data in the range of 0.8 to 7.0 μg kg(-1). The individual recoveries of PAHs following the microwave-assisted L-L extraction and SPE with silica were assessed using HPLC-FD with satisfactory results. PMID:23141362

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

    PubMed Central

    Tang, Pei-Ling; Hassan, Osman; Maskat, Mohamad Yusof; Badri, Khairiah

    2015-01-01

    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. PMID:26798644

  9. Hydrogen and carbon isotopic ratios of polycyclic aromatic compounds in two CM2 carbonaceous chondrites and implications for prebiotic organic synthesis

    NASA Astrophysics Data System (ADS)

    Huang, Yongsong; Aponte, José C.; Zhao, Jiaju; Tarozo, Rafael; Hallmann, Christian

    2015-09-01

    Study of meteoritic organic compounds offers a unique opportunity to understand the origins of the organic matter in the early Solar System. Meteoritic polycyclic aromatic hydrocarbons (PAHs) and heteropolycyclic aromatic compounds (HACs) have been studied for over fifty years, however; their hydrogen stable isotopic ratios (δD) have never been reported. Compound-specific δD measurements of PAHs and HACs are important, in part because the carbon isotopic ratios (δ13C) of various meteoritic PAHs cannot be readily distinguished from their terrestrial counterparts and it is difficult to rule out terrestrial contamination based on carbon isotopic ratios alone. In this study, we have extracted and identified more than sixty PAHs and HACs present in two CM2 carbonaceous chondrites Murchison and LON 94101. Their carbon and hydrogen stable isotopic ratios (δ13C and δD) were measured and used to discuss about their synthetic environments and formation mechanisms. The concentration of aromatic compounds is ∼30% higher in Murchison than in the Antarctic meteorite LON 94101, but both samples contained similar suites of PAHs and HACs. All PAHs and HACs found exhibited positive δD values (up to 1100‰) consistent with an extraterrestrial origin, indicating the relatively low δ13C values are indeed an inherent feature of the meteoritic aromatic compounds. The hydrogen isotopic data suggest aromatic compounds in carbonaceous chondrites were mainly formed in the cold interstellar environments. Molecular level variations in hydrogen and carbon isotopic values offer new insights to the formation pathways for the aromatic compounds in carbonaceous chondrites.

  10. Polymeric brominated flame retardants: are they a relevant source of emerging brominated aromatic compounds in the environment?

    PubMed

    Gouteux, Bruno; Alaee, Mehran; Mabury, Scott A; Pacepavicius, Grazina; Muir, Derek C G

    2008-12-15

    A purge and trap method was used to study the release of brominated organic compounds from polymeric brominated flame retardants (BFRs), a relatively unknown class of flame retardant materials. Among the volatile brominated organics released, pentabromotoluene (PBTo), pentabromoethylbenzene (PBEB), and hexabromobenzene (HBB) were of particular interest because of their high potential to persist in the environment The impact of a thermal stress on the release of these compounds was assessed by applying different constant temperatures for one hour to a polymeric BFR sample. Release rates ranged between 22 +/- 2.1 ng g(-1) h(-1) for PBEB to 2480 +/- 500 ng g(-1) h(-1) for PBTo at room temperature. These rates of release reached 65 +/- 11 ng g(-1) h(-1) for PBEB and 42400 +/- 4700 ng g(-1) h(-1) for PBTo at 100 degrees C. This suggests that the compounding of thermoplastic polyesters done at high temperatures, up to 290 degrees C, could lead to the release of significant amounts of volatile brominated compounds in the environment when crude polymeric BFRs are used as flame retardants. To assess if this unsuspected source of volatile brominated compounds to the environment was relevant to support air concentrations in the Great Lakes area, air samples collected at Egbert (ON, Canada) were analyzed and PBTo, PBEB, and HBB were detected at low levels in some air samples (<0.01 to 0.09 pg/m3). As a second step, a Level III fugacity model was run using release rates of PBTo, PBEB, and HBB determined in this study. Results of the model indicated that prevailing PBEB and HBB air concentrations were not supported by their release from polymeric BFRs but by the use of these compounds as additive BFRs. However, these model predictions suffered from a lack of information on the actual use of polymeric BFRs. Hence, further work is needed to assess the release of potentially persistent brominated aromatic compounds from polymeric BFRs. PMID:19174868

  11. Effect of intercalated aromatic sulfonates on uptake of aromatic compounds from aqueous solutions by modified Mg-Al layered double hydroxide

    SciTech Connect

    Kameda, Tomohito; Yamazaki, Takashi; Yoshioka, Toshiaki

    2010-06-15

    In this study, we utilized Mg-Al layered double hydroxide (Mg-Al LDH) modified by intercalation with three aromatic sulfonates-2,7-naphthalene disulfonate (2,7-NDS{sup 2-}), benzenesulfonate (BS{sup -}), and benzenedisulfonate (BDS{sup 2-})-for the uptake of two aromatics-1,3-dinitrobenzene (DNB) and anisole (AS)-from aqueous solution and determined the effect of the aromatic sulfonates on the uptake of these aromatics. We found that the electron-rich aromatic ring of the intercalated aromatic sulfonates such as 2,7-NDS{sup 2-} undergoes strong {pi}-{pi} stacking interactions with the electron-poorer benzene ring of DNB in aqueous solution, and these interactions result in a higher uptake of DNB by the modified Mg-Al LDHs. In contrast, the electron-poor aromatic ring of the aromatic sulfonates such as BDS{sup 2-} undergoes weak {pi}-{pi} stacking interactions with the electron-poorer benzene ring of DNB, and these interactions result in a lower uptake of DNB by the modified Mg-Al LDHs.

  12. Advanced Model Compounds for Understanding Acid-Catalyzed Lignin Depolymerization: Identification of Renewable Aromatics and a Lignin-Derived Solvent.

    PubMed

    Lahive, Ciaran W; Deuss, Peter J; Lancefield, Christopher S; Sun, Zhuohua; Cordes, David B; Young, Claire M; Tran, Fanny; Slawin, Alexandra M Z; de Vries, Johannes G; Kamer, Paul C J; Westwood, Nicholas J; Barta, Katalin

    2016-07-20

    The development of fundamentally new approaches for lignin depolymerization is challenged by the complexity of this aromatic biopolymer. While overly simplified model compounds often lack relevance to the chemistry of lignin, the direct use of lignin streams poses significant analytical challenges to methodology development. Ideally, new methods should be tested on model compounds that are complex enough to mirror the structural diversity in lignin but still of sufficiently low molecular weight to enable facile analysis. In this contribution, we present a new class of advanced (β-O-4)-(β-5) dilinkage models that are highly realistic representations of a lignin fragment. Together with selected β-O-4, β-5, and β-β structures, these compounds provide a detailed understanding of the reactivity of various types of lignin linkages in acid catalysis in conjunction with stabilization of reactive intermediates using ethylene glycol. The use of these new models has allowed for identification of novel reaction pathways and intermediates and led to the characterization of new dimeric products in subsequent lignin depolymerization studies. The excellent correlation between model and lignin experiments highlights the relevance of this new class of model compounds for broader use in catalysis studies. Only by understanding the reactivity of the linkages in lignin at this level of detail can fully optimized lignin depolymerization strategies be developed. PMID:27310182

  13. pH and ionic strength effects on the binding constant between a nitrogen-containing polycyclic aromatic compound and humic acid.

    PubMed

    Chang, Kuei-Chen; Lee, Chon-Lin; Hsieh, Ping-Chieh; Brimblecombe, Peter; Kao, Shu-Min

    2015-09-01

    Polycyclic aromatic compounds (PACs) are widespread environmental pollutants with a high potential to act as human carcinogens and mutagens. The behavior of PACs is significantly affected by their interactions with dissolved organic matter (DOM), such as their transport, solubility, bioavailability, and bioaccumulation in the aquatic environment. Being a basic PAC, benzo(h)quinoline (BQ) is the dominant species, as the solution's pH value is higher than BQ's pK a (pK a of BQ = 4.2). In contrast, benzo(h)quinolinium (BQH(+)) is the major species, as the solution's pH value is lower than its pK a. The binding constant (K DOC), measured by fluorescence quenching, between BQ/BQH(+) and Leonardite humic acid (LHA) would decrease 70 to 95 % and 20 to 90 % when increasing the ionic strength in acidic and neutral to basic conditions, respectively. The results can be attributed to the added cation (Na(+) and Mg(2+)), which forms a bridge with LHA and enhances the intramolecular reaction among these functional groups, therefore inducing the coiling up within the LHA molecule. In addition, the decrease of the K DOC with added MgCl2/MgSO4 (75-95 %) is higher than that with added NaCl/Na2SO4 (20-75 %), indicating that the K DOC was affected by the charge density of cations. The fluorescence intensity of BQH(+) in the absence of LHA (F 0) was found to decay only in the acidic solution with Cl(-), suggesting that Cl(-) might be a heavy atom serving as a quencher in an acidic solution. PMID:25940463

  14. Long-term performance and stability of a continuous granular airlift reactor treating a high-strength wastewater containing a mixture of aromatic compounds.

    PubMed

    Ramos, Carlos; Suárez-Ojeda, María Eugenia; Carrera, Julián

    2016-02-13

    Continuous feeding operation of an airlift reactor and its inoculation with mature aerobic granules allowed the successful treatment of a mixture of aromatic compounds (p-nitrophenol, o-cresol and phenol). Complete biodegradation of p-nitrophenol, o-cresol, phenol and their metabolic intermediates was achieved at an organic loading rate of 0.61 g COD L(-1)d(-1). Stable granulation was obtained throughout the long-term operation (400 days) achieving an average granule size of 2.0 ± 1 mm and a sludge volumetric index of 26 ± 1 mL g(-1) TSS. The identified genera in the aerobic granular biomass were heterotrophic bacteria able to consume aromatic compounds. Therefore, the continuous feeding regimen and the exposure of aerobic granules to a mixture of aromatic compounds make possible to obtain good granulation and high removal efficiency. PMID:26530892

  15. Highly Fluorescent Group 13 Metal Complexes with Cyclic, Aromatic Hydroxamic Acid Ligands

    SciTech Connect

    Seitz, Michael; Moore, Evan G.; Raymond, Kenneth N.

    2008-02-11

    The neutral complexes of two ligands based on the 1-oxo-2-hydroxy-isoquinoline (1,2-HOIQO) motif with group 13 metals (Al, Ga, In) show bright blue-violet luminescence in organic solvents. The corresponding transition can be attributed to ligand-centered singlet emission, characterized by a small Stokes shifts of only a few nm combined with lifetimes in the range between 1-3 ns. The fluorescence efficiency is high, with quantum yields of up to 37% in benzene solution. The crystal structure of one of the indium(III) complexes (trigonal space group R-3, a = b = 13.0384(15) {angstrom}, c = 32.870(8) {angstrom}, ? = {beta} = 90{sup o}, {gamma} = 120{sup o}, V = 4839.3(14) {angstrom}{sup 3}, Z = 6) shows a six-coordinate geometry around the indium center which is close to trigonal-prismatic, with a twist angle between the two trigonal faces of 20.7{sup o}. Time-dependent density functional theory (TD-DFT) calculations (Al and Ga: B3LYP/6-31G(d)); In: B3LYP/LANL2DZ of the fac and mer isomers with one of the two ligands indicate that there is no clear preference for either one of the isomeric forms of the metal complexes. In addition, the metal centers do not have a significant influence on the electronic structure, and as a consequence, on the predominant intraligand optical transitions.

  16. Polycyclic aromatic compounds in cod (Gadus morhua) from the Northwest Atlantic and St. Lawrence Estuary.

    PubMed

    Hellou, J; Upshall, C; Payne, J F; Hodson, P V

    1994-05-01

    There is limited information available on levels of polycyclic aromatic hydrocarbons (PAH) in major fish populations including populations from the Northwest Atlantic. The cod (Gadus morhua) stocks off eastern Canada form the basis of one of the world's most important fisheries. Muscle tissues of cod collected from Northwest Atlantic Fisheries Organisation (NAFO) management Divisions 2J, 3K and 3Ps off Newfoundland and Labrador, as well as three contaminated sites in the Gulf of St. Lawrence were analyzed for total polycyclic aromatic (PAC) by fluorimetry. Concentrations were determined in terms of crude oil and chrysene equivalents in line with recommendations of the International Oceanographic Commission. Overall, relatively low concentrations of PAC were found, the highest values generally being below 0.1 microgram/g (dry weight) in terms of chrysene equivalents. Similarly, only trace levels of a few PAH were detected in composite samples analyzed by gas chromatography-mass spectrometry (GC-MS). It is of interest that the highest levels of PAC were found in fish from NAFO Division 3K, while concentrations in fish from the two contiguous zones, 2J and 3Ps, as well as the Gulf of St. Lawrence, were similar. Division 3K is a major fishing zone and it is important to determine if trawler fleets are important sources of hydrocarbons derived from fossil fuels, in this and similar fishing areas of the world's oceans. PMID:8016631

  17. Determination of polycyclic aromatic compounds and heavy metals in sludges from biological sewage treatment plants.

    PubMed

    Bodzek, D; Janoszka, B; Dobosz, C; Warzecha, L; Bodzek, M

    1997-07-11

    The procedure of the analysis of polycyclic aromatic hydrocarbons (PAHs) and their derivatives in the sludges from biological sewage treatment plants has been worked out. The analysis included isolation of organic matter from sludges, separation of the extract into fractions of similar chemical character, qualitative-quantitative analysis of individual PAHs and their nitrogenated and oxygenated derivatives. Liquid-solid chromatography, solid-phase extraction and semipreparative band thin-layer chromatography techniques were used for the separation. Capillary gas chromatography-mass spectrometry analysis of the separated fractions enabled identification of more than 21 PAHs, including hydrocarbons which contained 2-6 aromatic rings as well as their alkyl derivatives, 10 oxygen derivatives, 9 nitroarenes, aminoarenes and over 20 azaarenes and carbazoles. Using the capillary gas chromatography-flame ionization detection technique the content of 17 dominant PAHs was determined. The content of heavy metals was determined in investigated sludges with the use of atomic absorption spectrometry. The concentrations of the respective metals could be ranked in the order Cd < Co < Ni < Pb < Cr < or = Cu < Mn < Zn < Fe. The sludges were analysed for the first time in Poland in view of their possible utilisation in agriculture and in cultivating dumps of coal mine wastes, taking into consideration the contents of toxic organic pollutants and heavy metals. PMID:9253190

  18. KINETIC STUDIES OF THE REDUCTION OF AROMATIC AZO COMPOUNDS IN ANAEROBIC SEDIMENT/WATER SYSTEMS

    EPA Science Inventory

    The reductive transformation of azobenzene and selected derivatives was investigated in anaerobic sediment/water systems. The azo compounds exhibited pseudo-first-order disappearance kinetics through at least three half-lives. The reduction kinetics of these compounds was studied...

  19. Anti-Prion Activity of a Panel of Aromatic Chemical Compounds: In Vitro and In Silico Approaches

    PubMed Central

    Ferreira, Natalia C.; Marques, Icaro A.; Conceição, Wesley A.; Macedo, Bruno; Machado, Clarice S.; Mascarello, Alessandra; Chiaradia-Delatorre, Louise Domeneghini; Yunes, Rosendo Augusto; Nunes, Ricardo José; Hughson, Andrew G.; Raymond, Lynne D.; Pascutti, Pedro G.; Caughey, Byron; Cordeiro, Yraima

    2014-01-01

    The prion protein (PrP) is implicated in the Transmissible Spongiform Encephalopathies (TSEs), which comprise a group of fatal neurodegenerative diseases affecting humans and other mammals. Conversion of cellular PrP (PrPC) into the scrapie form (PrPSc) is the hallmark of TSEs. Once formed, PrPSc aggregates and catalyzes PrPC misfolding into new PrPSc molecules. Although many compounds have been shown to inhibit the conversion process, so far there is no effective therapy for TSEs. Besides, most of the previously evaluated compounds failed in vivo due to poor pharmacokinetic profiles. In this work we propose a combined in vitro/in silico approach to screen for active anti-prion compounds presenting acceptable drugability and pharmacokinetic parameters. A diverse panel of aromatic compounds was screened in neuroblastoma cells persistently infected with PrPSc (ScN2a) for their ability to inhibit PK-resistant PrP (PrPRes) accumulation. From ∼200 compounds, 47 were effective in decreasing the accumulation of PrPRes in ScN2a cells. Pharmacokinetic and physicochemical properties were predicted in silico, allowing us to obtain estimates of relative blood brain barrier permeation and mutagenicity. MTT reduction assays showed that most of the active compounds were non cytotoxic. Compounds that cleared PrPRes from ScN2a cells, were non-toxic in the MTT assay, and presented a good pharmacokinetic profile were investigated for their ability to inhibit aggregation of an amyloidogenic PrP peptide fragment (PrP109–149). Molecular docking results provided structural models and binding affinities for the interaction between PrP and the most promising compounds. In summary, using this combined in vitro/in silico approach we have identified new small organic anti-scrapie compounds that decrease the accumulation of PrPRes in ScN2a cells, inhibit the aggregation of a PrP peptide, and possess pharmacokinetic characteristics that support their drugability. These compounds are

  20. Screening and determination of polycyclic aromatic hydrocarbons in seafoods using QuEChERS-based extraction and high-performance liquid chromatography with fluorescence detection.

    PubMed

    Gratz, Samuel R; Ciolino, Laura A; Mohrhaus, Angela S; Gamble, Bryan M; Gracie, Jill M; Jackson, David S; Roetting, John P; McCauley, Heather A; Heitkemper, Douglas T; Fricke, Fred L; Krol, Walter J; Arsenault, Terri L; White, Jason C; Flottmeyer, Michele M; Johnson, Yoko S

    2011-01-01

    A rapid, sensitive, and accurate method for the screening and determination of polycyclic aromatic hydrocarbons (PAHs) in edible seafood is described. The method uses quick, easy, cheap, effective, rugged, and safe (QuEChERS)-based extraction and HPLC with fluorescence detection (FLD). The method was developed and validated in response to the massive Deepwater Horizon oil spill in the Gulf of Mexico. Rapid and highly sensitive PAH screening methods are critical tools needed for oil spill response; they help to assess when seafood is safe for harvesting and consumption. Sample preparation involves SPE of edible seafood portions with acetonitrile, followed by the addition of salts to induce water partitioning. After centrifugation, a portion of the acetonitrile layer is filtered prior to analysis via HPLC-FLD. The chromatographic method uses a polymeric C18 stationary phase designed for PAH analysis with gradient elution, and it resolves 15 U.S. Environmental Protection Agency priority parent PAHs in fewer than 20 min. The procedure was validated in three laboratories for the parent PAHs using spike recovery experiments at PAH fortification levels ranging from 25 to 10 000 microg/kg in oysters, shrimp, crab, and finfish, with recoveries ranging from 78 to 99%. Additional validation was conducted for a series of alkylated homologs of naphthalene, dibenzothiophene, and phenanthrene, with recoveries ranging from 87 to 128%. Method accuracy was further assessed based on analysis of National Institute of Standards and Technology Standard Reference Material 1974b. The method provides method detection limits in the sub to low ppb (microg/kg) range, and practical LOQs in the low ppb (microg/kg) range for most of the PAH compounds studied. PMID:22165027

  1. Toxicity of eight polycyclic aromatic compounds to red clover (Trifolium pratense), ryegrass (Lolium perenne), and mustard (Sinapsis alba).

    PubMed

    Sverdrup, Line E; Krogh, Paul Henning; Nielsen, Torben; Kjaer, Christian; Stenersen, Jørgen

    2003-12-01

    The effect of eight polycyclic aromatic compounds (PACs) on the seed emergence and early life-stage growth of three terrestrial plants (Sinapsis alba, Trifolium pratense and Lolium perenne) were studied in a greenhouse, using a Danish agricultural soil with an organic carbon content of 1.6%. After three weeks of exposure, seed emergence and seedling weight (fresh weight and dry weight) were determined. Exposure concentrations were verified with chemical analysis. The substances tested were four polycyclic aromatic hydrocarbons (fluoranthene, pyrene, phenanthrene and fluorene), the N-, S-, and O-substituted analogues of fluorene (carbazole, dibenzothiophene and dibenzofuran, respectively), and the quinoline representative acridine. Seedling growth was a far more sensitive endpoint than seed emergence for all substances. Concentrations estimated to give a 20% reduction of seedling fresh weight (EC20-values) ranged from 36 to 290 mgkg(-1) for carbazole, 43 to 93 mgkg(-1) for dibenzofuran, 37 to 110 mgkg(-1) for dibenzothiophene, 140 to 650 mgkg(-1) for fluoranthene, 55 to 380 mgkg(-1) for fluorene, 37 to 300 mgkg(-1) for phenanthrene, and 49 to 1300 mgkg(-1) for pyrene. For acridine, no toxicity was observed within the concentration range tested (1-1000 mgkg(-1)). As illustrated by the EC20-values, there was a rather large difference in sensitivity between the species, and T. pratense was the most sensitive of the species tested. PMID:14505722

  2. Angular distribution of light emission from compound-eye cornea with conformal fluorescent coating

    NASA Astrophysics Data System (ADS)

    Martín-Palma, Raúl J.; Miller, Amy E.; Pulsifer, Drew P.; Lakhtakia, Akhlesh

    2014-09-01

    The complex morphology of the apposition compound eyes of insects of many species provides them a wide angular field of view. This characteristic makes these eyes attractive for bioreplication as artificial sources of light. The cornea of a blowfly eye was conformally coated with a fluorescent thin film with the aim of achieving wide field-of-view emission. On illumination by shortwave-ultraviolet light, the conformally coated eye emitted visible light whose intensity showed a weaker angular dependence than a fluorescent thin film deposited on a flat surface.

  3. Topochemical control of the photodimerization of aromatic compounds by γ-cyclodextrin thioethers in aqueous solution

    PubMed Central

    Wang, Hai Ming

    2013-01-01

    Summary The formation of soluble 1:2 complexes within hydrophilic γ-cyclodextrin (γ-CD) thioethers allows to perform photodimerizations of aromatic guests under controlled, homogenous reaction conditions. The quantum yields for unsubstituted anthracene, acenaphthylene, and coumarin complexed in these γ-CD thioethers were found to be up to 10 times higher than in the non-complexed state. The configuration of the photoproduct reflected the configuration of the dimeric inclusion complex of the guest. Anti-parallel orientation of acenaphthylene within the CD cavity led to the exclusive formation of the anti photo-dimer in quantitative yield. Parallel orientation of coumarin within the complex of a CD thioether led to the formation of the syn head-to-head dimer. The degree of complexation of coumarin could be increased by employing the salting out effect. PMID:24062853

  4. Mössbauer Spectroscopic Study of Iron Containing Hydrotalcite Catalysts for the Reduction of Aromatic Nitro Compounds

    NASA Astrophysics Data System (ADS)

    Sanchez-Valente, J.; Millet, J. M. M.; Figueras, F.; Fournes, L.

    2000-12-01

    Carbonated layered double magnesium hydroxides containing Fe with hydrotalcite structure which are active and selective catalysts for the reduction of aromatic nitro compounds by hydrazine hydrate have been prepared and characterized by X-ray diffraction and Mössbauer spectroscopy. Using these techniques we have shown that when the Fe/(Fe + Mg) ratio was greater than 0.2, which corresponds to the natural phase composition, ferrihydrite Fe5HO8ṡ4H2O was formed. This last phase, characterized at room temperature by a superparamagnetic doublet, leads after activation under nitrogen at 723 K to small particles of ferric oxide. An in-situ study of the activated catalysts allowed us to show that only iron cations present in this phase could undergo an oxido-reduction under the conditions of catalysis and that the catalytic properties must be related to this last phase.

  5. Function and the biosynthesis of unusual corrinoids by a novel activation mechanism of aromatic compounds in anaerobic bacteria

    NASA Astrophysics Data System (ADS)

    Stupperich, E.; Eisinger, H. J.

    A corrinoid screening of several phylogenetically diverse ``archaebacteria'' revealed vitamin B12-like corrinoids. This indicates an optimized structure and function relationship of the corrinoids under different bacterial growth conditions during the early evolution of live. Some of these corrinoids have been substituted by modified corrinoids in growing cells without affecting the generation times of the bacteria. In this respect, the discovery of the unique para-cresolyl cobamide from the eubacterium Sporomusa ovata attracted attention. The unusual structure of this corrinoid was achieved by a biosynthesis proceeding via a novel and stereospecific activation mechanism of aromatic compounds. The corrinoid was detected both in the membrane fraction and in the soluble fraction of the cells. Methyltransfer is one of the probable functions of the para-cresolyl cobamide in Sporomusa.

  6. Development of Enantiospecific Coupling of Secondary and Tertiary Boronic Esters with Aromatic Compounds.

    PubMed

    Odachowski, Marcin; Bonet, Amadeu; Essafi, Stephanie; Conti-Ramsden, Philip; Harvey, Jeremy N; Leonori, Daniele; Aggarwal, Varinder K

    2016-08-01

    The stereospecific cross-coupling of secondary boronic esters with sp(2) electrophiles (Suzuki-Miyaura reaction) is a long-standing problem in synthesis, but progress has been achieved in specific cases using palladium catalysis. However, related couplings with tertiary boronic esters are not currently achievable. To address this general problem, we have focused on an alternative method exploiting the reactivity of a boronate complex formed between an aryl lithium and a boronic ester. We reasoned that subsequent addition of an oxidant or an electrophile would remove an electron from the aromatic ring or react in a Friedel-Crafts-type manner, respectively, generating a cationic species, which would trigger 1,2-migration of the boron substituent, creating the new C-C bond. Elimination (preceded by further oxidation in the former case) would result in rearomatization giving the coupled product stereospecifically. Initial work was examined with 2-furyllithium. Although the oxidants tested were unsuccessful, electrophiles, particularly NBS, enabled the coupling reaction to occur in good yield with a broad range of secondary and tertiary boronic esters, bearing different steric demands and functional groups (esters, azides, nitriles, alcohols, and ethers). The reaction also worked well with other electron-rich heteroaromatics and 6-membered ring aromatics provided they had donor groups in the meta position. Conditions were also found under which the B(pin)- moiety could be retained in the product, ortho to the boron substituent. This protocol, which created a new C(sp(2))-C(sp(3)) and an adjacent C-B bond, was again applicable to a range of secondary and tertiary boronic esters. In all cases, the coupling reaction occurred with complete stereospecificity. Computational studies verified the competing processes involved and were in close agreement with the experimental observations. PMID:27384259

  7. Examining spatial patterns in polycyclic aromatic compounds measured in stream macroinvertebrates near a small subarctic oil and gas operation.

    PubMed

    Korosi, J B; Eickmeyer, D C; Chin, K S; Palmer, M J; Kimpe, L E; Blais, J M

    2016-03-01

    The Cameron River runs through a small, remote petrochemical development in the Cameron Hills (Northwest Territories, Canada). In order to evaluate the exposure of aquatic biota to contaminants from oil and gas activities, we measured polycyclic aromatic compounds (PACs) in macroinvertebrates collected from sites and tributaries along the Cameron River, including upstream and downstream of the development, and sites located near drilled wells (developed). Macroinvertebrate tissue PAC burdens ranged from 0.2-2.8 μg g(-1) lipid for unsubstituted compounds, and from 4.2-63.2 μg g(-1) lipid for alkylated compounds, relatively low compared to similar studies from more industrialized regions in North America. There was no significant difference in tissue PAC burdens between upstream, downstream, or developed sites (p = 0.12), although alkyl PACs in five out of seven developed sites were higher than the regional average. Petrogenic PACs were dominant in most samples, including alkyl fluorines, alkyl phenanthrene/anthracenes, and alkyl dibenzothiophenes. Minimal changes in PAC composition in macroinvertebrate tissues were detected along the Cameron River, with the exception of the two sites furthest downstream that had high concentrations of C3-C4 naphthalene. Overall, our results suggest that oil and gas development in the Cameron Hills has not resulted in substantial increases in PAC bioaccumulation in stream macroinvertebrates, although the potential that alkyl naphthalenes are being transported downstream from the development warrants further attention. PMID:26911593

  8. Aromatic amine N-oxide organometallic compounds: searching for prospective agents against infectious diseases.

    PubMed

    Rodríguez Arce, Esteban; Mosquillo, M Florencia; Pérez-Díaz, Leticia; Echeverría, Gustavo A; Piro, Oscar E; Merlino, Alicia; Coitiño, E Laura; Maríngolo Ribeiro, Camila; Leite, Clarice Q F; Pavan, Fernando R; Otero, Lucía; Gambino, Dinorah

    2015-08-28

    In search of prospective agents against infectious diseases, 1,1'-bis(diphenylphosphino)ferrocene pyridine-2-thiolato-1-oxide M(ii) hexafluorophosphate compounds [M(mpo)(dppf)](PF6), where M = palladium or platinum, were synthesized and fully characterized in the solid state and in solution using experimental and DFT computational techniques. The compounds are isomorphous and the M(ii) transition metal ions are in a nearly planar trapezoidal cis-coordination bound to the pyridine-2-thiolato-1-oxide (mpo) and to the 1,1'-bis(diphenylphosphino)ferrocene molecules, both acting as bidentate ligands. Both compounds showed high cytotoxic activity on Trypanosoma cruzi and Mycobacterium tuberculosis (MTB) and acceptable selectivities towards MTB, but good to excellent selectivity index values as anti-T. cruzi compounds. The inclusion of the ferrocene moiety (dppf ligand) improved the selectivity towards the parasite when compared to the previously reported [M(mpo)2] complexes. Related to the probable mechanism of action of the complexes, molecular docking studies on modelled T. cruzi NADH-fumarate reductase (TcFR) predicted that both be very good inhibitors of the enzyme. The effect of the compounds on the enzyme activity was experimentally confirmed using T. cruzi protein extracts. According to all obtained results, both [M(mpo)(dppf)](PF6) compounds could be considered prospective anti-trypanosomal agents that deserve further research. PMID:26203896

  9. Reactivity of polycyclic aromatic compounds (PAHs, NPAHs and OPAHs) adsorbed on natural aerosol particles exposed to atmospheric oxidants

    NASA Astrophysics Data System (ADS)

    Ringuet, Johany; Albinet, Alexandre; Leoz-Garziandia, Eva; Budzinski, Hélène; Villenave, Eric

    2012-12-01

    Reactivity of polycyclic aromatic compounds (PACs) adsorbed on natural aerosol particles exposed to different atmospheric oxidants (O3, OH and NO2/O3 mixture) was studied. Decay of polycyclic aromatic hydrocarbons (PAHs) and formation/decay of oxygenated PAHs (OPAHs) and nitrated PAHs (NPAHs) were monitored. Overall, benzo[a]pyrene appeared to be the most reactive PAH (degradation of 50%). Only its nitrated derivative, 6-nitrobenzo[a]pyrene, was significantly formed explaining just 0.4% of reacted benzo[a]pyrene. No other nitrated or oxygenated benzo[a]pyrene derivatives were detected. Interestingly, B[e]P and In[1,2,3,c,d]P, which are usually considered as quite stable PAHs, also underwent decay in all experiments. In presence of O3, ketones were significantly formed but their amount was not totally explained by decay of parent PAH. These results suggest that PAH derivatives could be formed from the reaction of other compounds than their direct parent PAHs and raise the question to know if the oxidation of methyl-PAHs, identified in vehicle-exhausts, could constitute this missing source of OPAHs. NPAHs were significantly formed in presence of O3/NO2 and OH. Surprisingly, NPAH formation was clearly observed during O3 experiments. Nitrated species, already associated with aerosol particles (NO3-, NO2-) or formed by ozonation of particulate nitrogen organic matter, could react with PAHs to form NPAHs. Heterogeneous formation of 2-nitropyrene from pyrene oxidation was for the first time observed, questioning its use as an indicator of NPAH formation in gaseous phase. Equally, formation of 2-nitrofluoranthene by heterogeneous reaction of fluoranthene with O3/NO2 was clearly shown, while only its formation by homogeneous processes (gaseous phase) is reported in the literature. Finally, results obtained highlighted the dependence of heterogeneous PAH reactivity with the substrate nature and the importance to focus reactivity studies on natural particles, whatever the

  10. Aqueous and tissue residue-based interspecies correlation estimation models provide conservative hazard estimates for aromatic compounds.

    PubMed

    Bejarano, Adriana C; Barron, Mace G

    2016-01-01

    Interspecies correlation estimation (ICE) models were developed for 30 nonpolar aromatic compounds to allow comparison of prediction accuracy between 2 data compilation approaches. Type 1 models used data combined across studies, and type 2 models used data combined only within studies. Target lipid (TLM) ICE models were also developed using target lipid concentrations of the type 2 model dataset (type 2-TLM). Analyses were performed to assess model prediction uncertainty introduced by each approach. Most statistically significant models (90%; 266 models total) had mean square errors < 0.27 and adjusted coefficients of determination (adj R(2) ) > 0.59, with the lowest amount of variation in mean square errors noted for type 2-TLM followed by type 2 models. Cross-validation success (>0.62) across most models (86% of all models) confirmed the agreement between ICE predicted and observed values. Despite differences in model predictive ability, most predicted values across all 3 ICE model types were within a 2-fold difference of the observed values. As a result, no statistically significant differences (p > 0.05) were found between most ICE-based and empirical species sensitivity distributions (SSDs). In most cases hazard concentrations were within or below the 95% confidence intervals of the direct-empirical SSD-based values, regardless of model choice. Interspecies correlation estimation-based 5th percentile (HC5) values showed a 200- to 900-fold increase as the log KOW increased from 2 to 5.3. Results indicate that ICE models for aromatic compounds provide a statistically based approach for deriving conservative hazard estimates for protecting aquatic life. PMID:26184086

  11. Arhodomonas sp. Strain Seminole and Its Genetic Potential To Degrade Aromatic Compounds under High-Salinity Conditions

    PubMed Central

    Dalvi, Sonal; Nicholson, Carla; Najar, Fares; Roe, Bruce A.; Canaan, Patricia; Hartson, Steven D.

    2014-01-01

    Arhodomonas sp. strain Seminole was isolated from a crude oil-impacted brine soil and shown to degrade benzene, toluene, phenol, 4-hydroxybenzoic acid (4-HBA), protocatechuic acid (PCA), and phenylacetic acid (PAA) as the sole sources of carbon at high salinity. Seminole is a member of the genus Arhodomonas in the class Gammaproteobacteria, sharing 96% 16S rRNA gene sequence similarity with Arhodomonas aquaeolei HA-1. Analysis of the genome predicted a number of catabolic genes for the metabolism of benzene, toluene, 4-HBA, and PAA. The predicted pathways were corroborated by identification of enzymes present in the cytosolic proteomes of cells grown on aromatic compounds using liquid chromatography-mass spectrometry. Genome analysis predicted a cluster of 19 genes necessary for the breakdown of benzene or toluene to acetyl coenzyme A (acetyl-CoA) and pyruvate. Of these, 12 enzymes were identified in the proteome of toluene-grown cells compared to lactate-grown cells. Genomic analysis predicted 11 genes required for 4-HBA degradation to form the tricarboxylic acid (TCA) cycle intermediates. Of these, proteomic analysis of 4-HBA-grown cells identified 6 key enzymes involved in the 4-HBA degradation pathway. Similarly, 15 genes needed for the degradation of PAA to the TCA cycle intermediates were predicted. Of these, 9 enzymes of the PAA degradation pathway were identified only in PAA-grown cells and not in lactate-grown cells. Overall, we were able to reconstruct catabolic steps for the breakdown of a variety of aromatic compounds in an extreme halophile, strain Seminole. Such knowledge is important for understanding the role of Arhodomonas spp. in the natural attenuation of hydrocarbon-impacted hypersaline environments. PMID:25149520

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

    PubMed

    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. PMID:25449108

  13. N,N'-Dithiobisphthalimide, a disulfide aromatic compound, is a potent spermicide agent in humans.

    PubMed

    Florez, Martha; Díaz, Emilce S; Brito, Iván; González, Jorge; Morales, Patricio

    2011-12-01

    Several studies have shown that users of vaginal preparations containing nonoxynol-9 (N-9) are at a high risk for sexually transmitted diseases, including HIV. Therefore, there is a great interest in identifying compounds that can specifically inhibit sperm without damaging the vaginal lining, possess a powerful spermicide activity, and can be used in contraceptive vaginal preparations to replace N-9. In this work, we studied the spermostatic and/or spermicidal activity of five non-detergent, disulfide compounds on human sperm, HeLa cells, and Lactobacillus acidophilus. The motility and viability of human sperm in semen and culture medium was evaluated after treatment with different concentrations of the disulfide compounds (2.5 - 100 µM). In addition, we evaluated the cytotoxic effect on HeLa cells and L. acidophilus. We identified compound 101, N,N'-dithiobisphthalimide (No. CAS 7764-30-9), as the most effective molecule. It has a half maximal effective concentration (EC(50)) of 8 µM and a minimum effective concentration (defined as the concentration that immobilizes 100 percent of the sperm in 20 sec) of 24 µM. At these concentrations, compound 101 does not affect the viability of the sperm, HeLa cells, or L. acidophilus. Our results indicate that dithiobisphthalimide has a potent spermostatic, irreversible effect with no toxic effects on HeLa cells and L. acidophilus. PMID:21942567

  14. Tunable ultraviolet laser-induced fluorescence detection of trace plastics and dissolved organic compounds in water

    NASA Astrophysics Data System (ADS)

    Sivaprakasam, Vasanthi; Killinger, Dennis K.

    2003-11-01

    We developed a tunable (220-285-nm) UV and fixed 266-nm laser-induced fluorescence (LIF) system using a spectrometer and a cooled CCD imaging detector to measure the excitation-emission matrix spectra of various compounds in water, including quinine sulfate and plastic compound bisphenol-A. The LIF instrument was used for the fast, nonspecific determination of trace amounts of dissolved organic compounds present in natural water supplies and various brand name bottled distilled water and bottled drinking water. Plastic-related compounds that leached out of plastic utensils and containers were also detected with this instrument. The sensitivity of the system was approximately 1-2 orders of magnitude better than that for a commercial system.

  15. Tunable ultraviolet laser-induced fluorescence detection of trace plastics and dissolved organic compounds in water.

    PubMed

    Sivaprakasam, Vasanthi; Killinger, Dennis K

    2003-11-20

    We developed a tunable (220-285-nm) UV and fixed 266-nm laser-induced fluorescence (LIF) system using a spectrometer and a cooled CCD imaging detector to measure the excitation-emission matrix spectra of various compounds in water, including quinine sulfate and plastic compound bisphenol-A. The LIF instrument was used for the fast, nonspecific determination of trace amounts of dissolved organic compounds present in natural water supplies and various brand name bottled distilled water and bottled drinking water. Plastic-related compounds that leached out of plastic utensils and containers were also detected with this instrument. The sensitivity of the system was approximately 1-2 orders of magnitude better than that for a commercial system. PMID:14658478

  16. Investigation of chlorinated aromatic compounds in the environment: Methods development and data interpretation

    SciTech Connect

    Ding, Wanghsien.

    1989-01-01

    Detection of low levels of chlorinated benzene compounds (CLBZ) and polychlorinated biphenyls (PCBs) in soil samples has been investigated with respect to potential sources in an industrial area of western New York state. The extract obtained by steam distillation was used directly with minimal additional cleanup steps for high resolution gas chromatography/mass spectrometry (HRGC/MS) and high resolution gas chromatography with electron capture detection (HRGC/ECD) analysis. The Nielson-Kryger steam distillation technique was used to extract CLBZ compounds and PCB congeners from soil samples. The recoveries of the CLBZ compounds in soil samples were monitored by comparison of the response for the {sup 13}C-labelled analogues in each isomeric group. The mean recoveries from field samples ranged from 63% to 76%. The recoveries of PCB congeners were measured using four air-dried subsurface soils which were spiked with Aroclors standard mixture. The mean recoveries of most PCB congeners ranged from 80% to 99%. Using HRGC/MS in the selected ion monitoring mode (SIM), a detection limit below 10 pg/g (10 pptr, parts per trillion) of the CLBZ compounds was achieved. For GC/ECD, an Apiezon L-coated glass capillary column was used to determine PCB congeners at background levels. More than 69 PCB congeners were separated on this column. The detection limit for an individual congener was about 0.01 ng/g. Application of SIMCA (SImple Modeling by Chemical Analogy) pattern recognition and multiple discriminant analysis showed that the pattern of CLBZ compounds in soil samples collected near Love Canal was similar to the patterns from the other areas in the Niagara Falls area. The highest concentrations of CLBZ compounds were detected in the area which is near and downwind from an industrial center with many potential sources of airborne emissions.

  17. Dissolved-oxygen quenching of in-situ fluorescence measurements

    NASA Astrophysics Data System (ADS)

    Chudyk, Wayne; Tonaszuck, David; Pohlig, Kenneth

    1993-04-01

    In-situ fluorescence measurements of aromatic organic ground water contaminants do not always agree with gas chromatographic methods. Dissolved oxygen quenching of fluorescence may be an interferant in field measurements. Two standard fluorescent aromatics, quinine sulfate and naphthalene, were evaluated in this study. Over the range of dissolved oxygen concentrations expected to be encountered in the field, no effects of oxygen quenching on fluorescence of these compounds was observed. Quenching of quinine sulfate fluorescence by sodium chloride was observed using this system. Sodium chloride quenching was shown to follow the Stern-Volmer relation.

  18. Synthesis and fluorescence properties of six fluorescein-nitroxide radical hybrid-compounds.

    PubMed

    Sato, Shingo; Endo, Susumu; Kurokawa, Yusuke; Yamaguchi, Masaki; Nagai, Akio; Ito, Tomohiro; Ogata, Tateaki

    2016-12-01

    Six fluorescein-nitroxide radical hybrid-compounds (2ab, 3ab, 4, and 5) were synthesized by the condensation of 5- or 6-carboxy-fluorescein and 4-amino-TEMPO (2ab), 5- or 6-aminofluorescein and 4-carboxy-TEMPO (3ab), and fluorescein and 4-carboxy-TEMPO (4), or by reaction of the 3-hydroxyl group of fluorescein with DPROXYL-3-ylmethyl methanesulfonate (5). Fluorescence intensities (around 520nm) after reduction of the radical increased to 1.43-, 1.38-, and 1.61-folds for 2a, 2b and 3b respectively; 3a alone exhibited a decrease in intensity on reduction. Since 4 was readily solvolyzed in PBS or even methanol to afford fluorescein and 4-carboxy-TEMPO, its fluorescence change could not be measured. Hybrid compound 5 containing an ether-linkage between the fluorescein phenol and 3-hydroxymethyl-DPROXYL hydroxyl centers, was stable and on reduction, showed a maximum increase (3.21-fold) in relative fluorescence intensity in PBS (pH5.0), despite its remarkably low absolute fluorescence intensity. PMID:27337053

  19. Solid compounds of europium and terbium with some aromatic carboxylic acids

    SciTech Connect

    Chupakhina, R.A.; Biryulina, V.N.; Kasimova, L.V.; Balakhonov, V.G.

    1986-10-20

    By the reactions of europium and terbium hydroxides with aqueous solutions of benzoic, salicylic, phthalic, and phthalaldehydic acids, compounds were obtained with the compositions: for phthalic acid M/sub 2/L/sub 3/ x 3H/sub 2/O, and for the other acids ML/sub 3/ x 3H/sub 2/O, in which M = Eu/sup 3 +/, Tb/sup 3 +/; L is the anion of the corresponding acid. The compounds of europium and terbium with phthalaldehydric acid were prepared for the first time.

  20. Post-source decay of alkylated and functionalized polycyclic aromatic compounds.

    PubMed

    Frache, Gilles; Krier, Gabriel; Vernex-Loset, Lionel; Muller, Jean-François; Manuelli, Pascal

    2007-01-01

    Post-source decay (PSD) is a valuable tool for providing structural information from large molecules by time-of-flight mass spectrometry (TOFMS). We used PSD to obtain this type of data from small molecules in the laser desorption/ionization (LDI) study of diesel engine exhaust particles. As the original nitrogen laser (lambda = 337 nm, E = 3.5 eV/photon) of our TOF mass spectrometer does not yield sufficient energy to ionize polycyclic aromatic hydrocarbons (PAHs), a second laser with a shorter wavelength has been coupled to the instrument. The fourth harmonic of a Nd:YAG laser (lambda = 266 nm, 4.6 eV/photon) has been chosen to achieve two-photon single-step desorption/ionization of PAHs. The PSD fragmentation of functionalized, alkylated and sulfur PAHs is discussed. Diesel engine exhaust particles are also studied as an example of a real complex sample. This technique is presented herein as a way to identify small molecules in environmental samples. Information provided by LDI-PSD-TOFMS can be a way to distinguish pollutants with very close molecular weights even if the resolving power of a TOF mass spectrometer is not sufficient. PMID:17639565

  1. Ring Selective Generation of Isobenzofuran for Divergent Access to Polycyclic Aromatic Compounds.

    PubMed

    Akita, Rie; Kawanishi, Kazuki; Hamura, Toshiyuki

    2015-06-19

    Ring selective generation of isobenzofuran, a formal equivalent to bis-isobenzofuran, was developed. Importantly, selective introduction of functionalities and/or fused rings in the isobenzofuran core by iterative cycloadditions can achieve the divergent construction of polycyclic compounds. This selective approach enables us to prepare a regioisomeric pair of pentacenes. PMID:26057708

  2. Methanogenic Inhibition by Roxarsone (4-Hydroxy-3-nitrophenylarsonic acid) and Related Aromatic Arsenic Compounds

    PubMed Central

    Sierra-Alvarez, Reyes; Cortinas, Irail; Field, Jim A.

    2009-01-01

    Roxarsone (4-hydroxy-3-nitro-phenylarsonic acid) and p-arsanilic acid (4-aminophenylarsonic acid) are feed additives widely used in the broiler and swine industry. This study evaluated the inhibitory effect of roxarsone, p-arsanilic, and other phenylarsonic compounds on the activity of acetate- and H2-utilizing methanogenic microorganisms. Roxarsone, p-arsanilic, and 4-hydroxy-3-aminophenylarsonic acid (HAPA) inhibited acetoclastic and hydrogenotrophic methanogens when supplemented at concentrations of 1 mM, and their inhibitory effect increased sharply with incubation time. Phenylarsonic acid (1 mM) inhibited acetoclastic but not H2-utilizing methanogens. HAPA, a metabolite from the anaerobic biodegradation of roxarsone, was found to be sensitive to autooxidation by oxygen. The compound (2.6 mM) caused low methanogenic inhibition (only 14.2%) in short-term assays of 12 h when autooxidation was prevented by supplementing HAPA solutions with ascorbate. However, ascorbate-free HAPA solutions underwent spontaneous autooxidation in the presence of oxygen, leading to the formation of highly inhibitory compounds. These results confirm the microbial toxicity of organoarsenic compounds, and they indicate that biotic as well as abiotic transformations can potentially impact the fate and microbial toxicity of these contaminants in the environment. PMID:19889499

  3. Influence of extraction methodologies on the analysis of five major volatile aromatic compounds of citronella grass (Cymbopogon nardus) and lemongrass (Cymbopogon citratus) grown in Thailand

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Infusions of citronella grass (Cymbopogon nardus) and lemongrass (Cymbopogon citratus) have been commonly used in folk medicine in Thailand and other Asian countries. This study focuses on a systematic comparison of two extraction methods for major volatile aromatic compounds (VACs) of citronella g...

  4. Identification, characterization and quantitation of pyrogenic polycylic aromatic hydrocarbons and other organic compounds in tire fire products.

    PubMed

    Wang, Zhendi; Li, K; Lambert, P; Yang, Chun

    2007-01-12

    On 15 August 2001, a tire fire took place at the Pneu Lavoie Facility in Gatineau, Quebec, in which 4000 to 6000 new and recycled tires were stored along with other potentially hazardous materials. Comprehensive gas chromatography-mass spectrometry (GC-MS) analyses were performed on the tire fire samples to facilitate detailed chemical composition characterization of toxic polycyclic aromatic hydrocarbons (PAHs) and other organic compounds in samples. It is found that significant amounts of PAHs, particularly the high-ring-number PAHs, were generated during the fire. In total, 165 PAH compounds including 13 isomers of molecular weight (MW) 302, 10 isomers of MW 278, 10 isomers of MW 276, 7 isomers of MW 252, 7 isomers of MW 228, and 8 isomers of MW 216 PAHs were positively identified in the tire fire wipe samples for the first time. Numerous S-, O-, and N-containing PAH compounds were also detected. The identification and characterization of the PAH isomers was mainly based on: (1) a positive match of mass spectral data of the PAH isomers with the NIST authentic mass spectra database; (2) a positive match of the GC retention indices (I) of PAHs with authentic standards and with those reported in the literature; (3) agreement of the PAH elution order with the NIST (US National Institute of Standards and Technology) Standard Reference Material 1597 for complex mixture of PAHs from coal tar; (4) a positive match of the distribution patterns of PAH isomers in the SIM mode between the tire fire samples and the NIST Standard Reference Materials and well-characterized reference oils. Quantitation of target PAHs was done on the GC-MS in the selected ion monitoring (SIM) mode using the internal standard method. The relative response factors (RRF) for target PAHs were obtained from analyses of authentic PAH standard compounds. Alkylated PAH homologues were quantitated using straight baseline integration of each level of alkylation. PMID:17112533

  5. Treatment of sludge containing nitro-aromatic compounds in reed-bed mesocosms - Water, BOD, carbon and nutrient removal

    SciTech Connect

    Gustavsson, L.; Engwall, M.

    2012-01-15

    Highlights: Black-Right-Pointing-Pointer It is necessary to improve existing and develop new sludge management techniques. Black-Right-Pointing-Pointer One method is dewatering and biodegradation of compounds in constructed wetlands. Black-Right-Pointing-Pointer The result showed high reduction of all tested parameters after treatment. Black-Right-Pointing-Pointer Plants improve degradation and Phragmites australis is tolerant to xenobiotics. Black-Right-Pointing-Pointer The amount of sludge could be reduced by 50-70%. - Abstract: Since the mid-1970s, Sweden has been depositing 1 million ton d.w sludge/year, produced at waste water treatment plants. Due to recent legislation this practice is no longer a viable method of waste management. It is necessary to improve existing and develop new sludge management techniques and one promising alternative is the dewatering and treatment of sludge in constructed wetlands. The aim of this study was to follow reduction of organic carbon, BOD and nutrients in an industrial sludge containing nitro-aromatic compounds passing through constructed small-scale wetlands, and to investigate any toxic effect such as growth inhibition of the common reed Phragmites australis. The result showed high reduction of all tested parameters in all the outgoing water samples, which shows that constructed wetlands are suitable for carbon and nutrient removal. The results also showed that P. australis is tolerant to xenobiotics and did not appear to be affected by the toxic compounds in the sludge. The sludge residual on the top of the beds contained low levels of organic carbon and is considered non-organic and could therefore be landfilled. Using this type of secondary treatment method, the amount of sludge could be reduced by 50-70%, mainly by dewatering and biodegradation of organic compounds.

  6. Effect of Biofilm Formation by Oenococcus oeni on Malolactic Fermentation and the Release of Aromatic Compounds in Wine.

    PubMed

    Bastard, Alexandre; Coelho, Christian; Briandet, Romain; Canette, Alexis; Gougeon, Régis; Alexandre, Hervé; Guzzo, Jean; Weidmann, Stéphanie

    2016-01-01

    The winemaking process involves the alcoholic fermentation of must, often followed by malolactic fermentation (MLF). The latter, mainly carried out by the lactic acid bacterium Oenococcus oeni, is used to improve wine quality when acidity reduction is required. Moreover, it prevents microbial spoilage and improves the wine's organoleptic profile. Prior observations showed that O. oeni is able to resist several months in harsh wine conditions when adhered on oak barrels. Since biofilm is a prevailing microbial lifestyle in natural environments, the capacity of O. oeni to form biofilms was investigated on winemaking material such as stainless steel and oak chips. Scanning Electron Microscopy and Confocal Laser Scanning Microscopy showed that O. oeni was able to adhere to these surfaces and form spatially organized microcolonies embedded in extracellular substances. To assess the competitive advantage of this mode of life in wine, the properties of biofilm and planktonic cells were compared after inoculation in a fermented must (pH 3.5 or 3.2 and 12% ethanol) The results indicated that the biofilm culture of O. oeni conferred (i) increased tolerance to wine stress, and (ii) functional performance with effective malolactic activities. Relative gene expression focusing on stress genes and genes involved in EPS synthesis was investigated in a mature biofilm and emphasized the role of the matrix in increased biofilm resistance. As oak is commonly used in wine aging, we focused on the O. oeni biofilm on this material and its contribution to the development of wine color and the release of aromatic compounds. Analytical chromatography was used to target the main oak aging compounds such as vanillin, gaiacol, eugenol, whisky-lactones, and furfural. The results reveal that O. oeni biofilm developed on oak can modulate the wood-wine transfer of volatile aromatic compounds during MLF and aging by decreasing furfural, gaiacol, and eugenol in particular. This work showed that O

  7. Effect of Biofilm Formation by Oenococcus oeni on Malolactic Fermentation and the Release of Aromatic Compounds in Wine

    PubMed Central

    Bastard, Alexandre; Coelho, Christian; Briandet, Romain; Canette, Alexis; Gougeon, Régis; Alexandre, Hervé; Guzzo, Jean; Weidmann, Stéphanie

    2016-01-01

    The winemaking process involves the alcoholic fermentation of must, often followed by malolactic fermentation (MLF). The latter, mainly carried out by the lactic acid bacterium Oenococcus oeni, is used to improve wine quality when acidity reduction is required. Moreover, it prevents microbial spoilage and improves the wine’s organoleptic profile. Prior observations showed that O. oeni is able to resist several months in harsh wine conditions when adhered on oak barrels. Since biofilm is a prevailing microbial lifestyle in natural environments, the capacity of O. oeni to form biofilms was investigated on winemaking material such as stainless steel and oak chips. Scanning Electron Microscopy and Confocal Laser Scanning Microscopy showed that O. oeni was able to adhere to these surfaces and form spatially organized microcolonies embedded in extracellular substances. To assess the competitive advantage of this mode of life in wine, the properties of biofilm and planktonic cells were compared after inoculation in a fermented must (pH 3.5 or 3.2 and 12% ethanol) The results indicated that the biofilm culture of O. oeni conferred (i) increased tolerance to wine stress, and (ii) functional performance with effective malolactic activities. Relative gene expression focusing on stress genes and genes involved in EPS synthesis was investigated in a mature biofilm and emphasized the role of the matrix in increased biofilm resistance. As oak is commonly used in wine aging, we focused on the O. oeni biofilm on this material and its contribution to the development of wine color and the release of aromatic compounds. Analytical chromatography was used to target the main oak aging compounds such as vanillin, gaiacol, eugenol, whisky-lactones, and furfural. The results reveal that O. oeni biofilm developed on oak can modulate the wood-wine transfer of volatile aromatic compounds during MLF and aging by decreasing furfural, gaiacol, and eugenol in particular. This work showed that O

  8. Molecularly imprinted polymers for the analysis and removal of polychlorinated aromatic compounds in the environment: a review.

    PubMed

    Ndunda, Elizabeth N; Mizaikoff, Boris

    2016-05-23

    Synthetic receptors and in particular molecularly imprinted polymers (MIPs) are gaining relevance as selective sorbent materials and biomimetic recognition elements for analyzing polychlorinated aromatic compounds (PACs) in the environment. PACs are still ubiquitous toxic pollutants requiring their continuous environmental assessment for protecting humans and animals from exposure. Since nowadays most PACs occur at ultra-trace concentration levels and in complex matrices, the selectivity of MIPs renders them ideally suited for facilitating either sample pre-treatment and quantitative enrichment, or acting as biomimetic recognition elements as an integral component of corresponding sensing schemes. Due to the diversity of PACs, imprinting polymers for these constituents appears particularly challenging. This review focuses on prevalent strategies towards successfully templating polymer materials towards polychlorinated biphenyls and their hydroxy forms, chlorophenols, dioxins and furans, and organochlorine pesticides, and successful applications of the polymer materials in monitoring of these compounds at trace-levels in real-world environmental matrices. Discussed are also group-selective sorbents for facilitating simultaneous detection and quantification of PACs. PMID:27109025

  9. Chapter 3. Determination of semivolatile organic compounds and polycyclic aromatic hydrocarbons in solids by gas chromatography/mass spectrometry

    USGS Publications Warehouse

    Zaugg, Steven D.; Burkhardt, Mark R.; Burbank, Teresa L.; Olson, Mary C.; Iverson, Jana L.; Schroeder, Michael P.

    2006-01-01

    A method for the determination of 38 polycyclic aromatic hydrocarbons (PAHs) and semivolatile organic compounds in solid samples is described. Samples are extracted using a pressurized solvent extraction system. The compounds of interest are extracted from the solid sample twice at 13,800 kilopascals; first at 120 degrees Celsius using a water/isopropyl alcohol mixture (50:50, volume-to-volume ratio), and then the sample is extracted at 200 degrees Celsius using a water/isopropyl alcohol mixture (80:20, volume-to-volume ratio). The compounds are isolated using disposable solid-phase extraction (SPE) cartridges containing divinylbenzene-vinylpyrrolidone copolymer resin. The cartridges are dried with nitrogen gas, and then sorbed compounds are eluted from the SPE material using a dichloromethane/diethyl ether mixture (80:20, volume-to-volume ratio) and passed through a sodium sulfate/Florisil SPE cartridge to remove residual water and to further clean up the extract. The concentrated extract is solvent exchanged into ethyl acetate and the solvent volume reduced to 0.5 milliliter. Internal standard compounds are added prior to analysis by capillary-column gas chromatography/mass spectrometry. Comparisons of PAH data for 28 sediment samples extracted by Soxhlet and the accelerated solvent extraction (ASE) method described in this report produced similar results. Extraction of PAH compounds from standard reference material using this method also compared favorably with Soxhlet extraction. The recoveries of PAHs less than molecular weight 202 (pyrene or fluoranthene) are higher by up to 20 percent using this ASE method, whereas the recoveries of PAHs greater than or equal to molecular weight 202 are equivalent. This ASE method of sample extraction of solids has advantages over conventional Soxhlet extraction by increasing automation of the extraction process, reducing extraction time, and using less solvent. Extract cleanup also is greatly simplified because SPE replaces

  10. Pilot-scale study on nitrogen and aromatic compounds removal in printing and dyeing wastewater by reinforced hydrolysis-denitrification coupling process and its microbial community analysis.

    PubMed

    Li, Chao; Ren, Hongqiang; Yin, Erqin; Tang, Siyuan; Li, Yi; Cao, Jiashun

    2015-06-01

    Aiming to efficiently dispose printing and dyeing wastewater with "high organic nitrogen and aromatic compounds, but low carbon source quality", the reinforced anaerobic hydrolysis-denitrification coupling process, based on improved UASB reactors and segregated collection-disposition strategy, was designed and applied at the pilot scale. Results showed that the coupling process displayed efficient removal for these two kinds of pollutants (nitrogen and aromatics), since the concentration of NH3-N (shortened as ρ (NH3-N)) < 8 mg/L, ρ (TN) < 15 mg/L with long-term stability for the effluent, and both species and abundances of aromatics reduced greatly by UASBs according to GC-MS. Microbial community analysis by PCR-DGGE showed that Bacteroidetes and Alphaproteobacteria were the dominant communities in the bioreactors and some kinds of VFAs-producing, denitrifying and aromatic ring opening microorganisms were discovered. Further, the nirK and bcrA genes quantification also indicated the coupling process owned outstanding denitrification and aromatic compound-degrading potential, which demonstrates that the coupling process owns admirable applicability for this kind of wastewater treatment. PMID:25613804

  11. Use of image analysis to estimate anthocyanin and UV-excited fluorescent phenolic compound levels in strawberry fruit

    PubMed Central

    Yoshioka, Yosuke; Nakayama, Masayoshi; Noguchi, Yuji; Horie, Hideki

    2013-01-01

    Strawberry is rich in anthocyanins, which are responsible for the red color, and contains several colorless phenolic compounds. Among the colorless phenolic compounds, some, such as hydroxycinammic acid derivatives, emit blue-green fluorescence when excited with ultraviolet (UV) light. Here, we investigated the effectiveness of image analyses for estimating the levels of anthocyanins and UV-excited fluorescent phenolic compounds in fruit. The fruit skin and cut surface of 12 cultivars were photographed under visible and UV light conditions; colors were evaluated based on the color components of images. The levels of anthocyanins and UV-excited fluorescent compounds in each fruit were also evaluated by spectrophotometric and high performance liquid chromatography (HPLC) analyses, respectively and relationships between these levels and the image data were investigated. Red depth of the fruits differed greatly among the cultivars and anthocyanin content was well estimated based on the color values of the cut surface images. Strong UV-excited fluorescence was observed on the cut surfaces of several cultivars, and the grayscale values of the UV-excited fluorescence images were markedly correlated with the levels of those fluorescent compounds as evaluated by HPLC analysis. These results indicate that image analyses can select promising genotypes rich in anthocyanins and fluorescent phenolic compounds. PMID:23853516

  12. Semipolar polycyclic aromatic compounds: identification of 15 priority substances and the need for regulatory steps under REACH regulation.

    PubMed

    Schwarz, Markus A; Behnke, Andreas; Brandt, Marc; Eisenträger, Adolf; Hassauer, Martin; Kalberlah, Fritz; Seidel, Albrecht

    2014-07-01

    Semipolar polycyclic aromatic compounds (sPACs) are frequently found in association with homocyclic polycyclic aromatic hydrocarbons (PAHs) in substances of unknown or variable composition, complex reaction products, or biological materials (UVCBs) from coal or crude oil and products derived thereof. However, major information deficiencies exist with regard to their prevalence and their toxicological and ecotoxicological potential, persistency, and bioaccumulation characteristics. Therefore, in this work, the environmental concern and relevance of sPACs was addressed in a general, stepwise approach. First, a large list of sPACs was collected and subsequently refined by assessing their persistence, bioaccumulation, and toxicity (PBT) properties by quantitative structure-activity relationship (QSAR) methods and their relevance by determining their respective frequency of occurrence. In this way, 15 priority sPACs were identified. These 15 priority sPACs were further characterized in detail with respect to their ecotoxicological properties, environmental behavior, carcinogenicity, and genotoxicity attributes. All of these 15 substances were quantified in distillate or product samples. In the next step, some principles for nomination of indicator substances, indicative for the overall content of sPACs, are derived. Data gaps on ecotoxicological endpoints preclude final conclusions, but the respective necessary supplemental tests were identified. Five of the 15 sPACs were tentatively characterized as potential substances of very high concern (SVHC) for the environment. The overall results of this study also clearly show that regulatory risk management of homocyclic PAHs within the European Regulation on Registration, Evaluation, Authorisation and Restriction of Chemicals (REACH) does not address the environmental concern created by sPACs within UVCBs from coal or crude oil. The study proves the need for additional regulatory steps under REACH and suggests indicator

  13. Stability of polycyclic aromatic compounds in polyurethane foam-type passive air samplers upon O3 exposure

    NASA Astrophysics Data System (ADS)

    Jariyasopit, Narumol; Liu, Yongchun; Liggio, John; Harner, Tom

    2015-11-01

    Stability of polycyclic aromatic compounds (PACs) in polyurethane foam (PUF) disks upon O3 exposure was studied in a flow tube. A wide range of PACs was evaluated by spiking PUF disks with PACs and exposing to O3 at concentrations that were equivalent to two months exposure, a typical deployment period for these passive air samplers. Ambient concentrations of O3 (∼50 ppb) at 0% and 50% relative humidity (RH) were applied. At 0% RH, 23 of 68 PACs yielded more than 50% loss after exposure. The mean percent loss was 30% with perylene and 9,10-dimethylanthracene the most reactive polycyclic aromatic hydrocarbons (PAHs) and alkylated PAHs, respectively. At 50% RH, 77% of the studied PACs was stable upon O3 exposure (PACexposed/PACunexposed > 0.7). The mean percent loss was 17% and only 7 of 68 PACs yielded greater than 50% loss. In general, the reactivity of most of the PACs decreased at higher RH, except for the reactive PAHs (acenaphthylene, 2,3-dimethylanthracene, 9,10-dimethylanthracene, dibenzothiophene, and 2-methyldibenzothiophene) which demonstrated lower RH dependence. The experimental conditions in this study represent a worst case scenario for the stability of PACs sorbed to PUF. In reality, the sampling of PACs in ambient air represents an 'aged' component of PACs where the most reactive species have already partially been removed. Also, PACs in ambient air will be associated with the particle phase to varying extents that will help to enhance their stability. Therefore, under regular operating conditions, over a 2-month exposure, we expect a minimal error in the measurement of total concentration of PACs in air using the PUF disk passive sampler.

  14. Development of an Interaction Assay between Single-Stranded Nucleic Acids Trapped with Silica Particles and Fluorescent Compounds

    PubMed Central

    Isoda, T.; Maeda, R.

    2012-01-01

    Biopolymers are easily denatured by heating, a change in pH or chemical substances when they are immobilized on a substrate. To prevent denaturation of biopolymers, we developed a method to trap a polynucleotide on a substrate by hydrogen bonding using silica particles with surfaces modified by aminoalkyl chains ([A-AM silane]/SiO2). [A-AM silane]/SiO2 was synthesized by silane coupling reaction of N-2-(aminoethyl)-3-aminopropyltrimethoxysilane (A-AM silane) with SiO2 particles with a diameter of 5 μm at 100 °C for 20 min. The surface chemical structure of [A-AM silane]/SiO2 was characterized by Fourier transform infrared spectroscopy and molecular orbital calculations. The surface of the silica particles was modified with A-AM silane and primary amine groups were formed. [A-AM silane]/SiO2 was trapped with single-stranded nucleic acids [(Poly-X; X = A (adenine), G (guanine) and C (cytosine)] in PBS solution at 37 °C for 1 h. The single-stranded nucleic acids were trapped on the surface of the [A-AM silane]/SiO2 by hydrogen bonding to form conjugated materials. The resulting complexes were further conjugated by derivatives of acridine orange (AO) as fluorescent labels under the same conditions to form [AO:Poly-X:A-AM silane]/SiO2 complexes. Changes in the fluorescence intensity of these complexes originating from interactions between the single-stranded nucleic acid and aromatic compounds were also evaluated. The change in intensity displayed the order [AO: Poly-G: A-AM silane]/SiO2 > [AO:Poly-A:A-AM silane]/SiO2 >> [AO:Poly-C:A-AM silane]/SiO2. This suggests that the single-stranded nucleic acids conjugated with aminoalkyl chains on the surfaces of SiO2 particles and the change in fluorescence intensity reflected the molecular interaction between AO and the nucleic-acid base in a polynucleotide. PMID:24955635

  15. Photobleaching of arterial fluorescent compounds: characterization of elastin, collagen and cholesterol time-resolved spectra during prolonged ultraviolet irradiation.

    PubMed

    Marcu, L; Grundfest, W S; Maarek, J M

    1999-06-01

    To study the photobleaching of the main fluorescent compounds of the arterial wall, we repeatedly measured the time-resolved fluorescence of elastin, collagen and cholesterol during 560 s of excitation with nitrogen laser pulses. Three fluence rate levels were used: 0.72, 7.25 and 21.75 microW/mm2. The irradiation-related changes of the fluorescence intensity and of the time-resolved fluorescence decay constants were characterized for the emission at 390, 430 and 470 nm. The fluorescence intensity at 390 nm decreased by 25-35% when the fluence delivered was 4 mJ/mm2, a common value in fluorescence studies of the arterial wall. Cholesterol fluorescence photobleached the most, and elastin fluorescence photobleached the least. Photobleaching was most intense at 390 nm and least intense at 470 nm such that the emission spectra of the three compounds were markedly distorted by photobleaching. The time-resolved decay constants and the fluorescence lifetime were not altered by irradiation when the fluence was below 4 mJ/mm2. The spectral distortions associated with photobleaching complicate the interpretation of arterial wall fluorescence in terms of tissue content in elastin, collagen and cholesterol. Use of the time-dependent features of the emission that are not altered by photobleaching should increase the accuracy of arterial wall analysis by fluorescence spectroscopy. PMID:10378012

  16. Model-aided characterization of Tenax-TA for aromatic compound uptake from water.

    PubMed

    Zhao, Dongye; Pignatello, Joseph J

    2004-07-01

    The polymer adsorbent Tenax has been widely employed for studying desorption of organic contaminants in soils and sediments and for correlating physical availability with bioavailability. Although Tenax has been invoked to act as an infinite sink that completely and instantaneously removes solutes from the aqueous phase, to our knowledge no systematic characterization of Tenax resins has been carried out. The present study provides equilibrium and kinetic parameters for the uptake of benzene, nitrobenzene, naphthalene, phenanthrene, and pyrene by Tenax in selected water-solute-Tenax systems, and it offers guidelines for the use of Tenax resins. Sorption isotherms of the test compounds on Tenax-TA are nonlinear, and most show an inflection at high concentration, marking a change in physical state from glassy to rubbery. A simple dual-mode model was applied to the isotherms below the apparent inflection point. Sorption parameters for dissolution and hole-filling domains each correlate with the octanol-water partition coefficient. The effects of dissolved organic matter and salinity on Tenax-TA uptake are minor. Regeneration of Tenax-TA by hot-methanol extraction increased its affinity for naphthalene. Inclusion of 23% graphitized carbon in the polymer reduced affinity for phenanthrene. Uptake rate data were fit by the dual-mode diffusion model, which assumes diffusion in the polymer matrix. The obtained diffusion rate parameter correlates with molecular size. Equilibrium and kinetic parameters for benzene and nitrobenzene were comparable despite a three-orders-of-magnitude difference in their Henry's law coefficients, indicating that a pathway to the Tenax surface through the vapor phase is not required. Extrapolating to typical conditions in soil-desorption studies reveals that single-solute uptake is 95% or more complete within 4 min for the test compounds and within 7 min for benzo[a]pyrene. Thus, Tenax is suitable for compounds with desorption from soil or

  17. Influence of a reaction medium on the oxidation of aromatic nitrogen-containing compounds by peroxyacids

    NASA Astrophysics Data System (ADS)

    Dutka, V. S.; Matsyuk, N. V.; Dutka, Yu. V.

    2011-01-01

    The influence of different solvents on the oxidation reaction rate of pyridine (Py), quinoline (QN), acridine (AN), α-oxyquinoline (OQN) and α-picolinic acid (APA) by peroxydecanoic acid (PDA) was studied. It was found that the oxidation rate grows in the series Py < QN < AN, and the rate of the oxidation reaction of compounds containing a substituent in the α position from a reactive center is significantly lower than for unsubstituted analogues. The effective energies of activation of the oxidation reaction were found. It was shown that in the first stage, the reaction mechanism includes the rapid formation of an intermediate complex nitrogen-containing compound, peroxyacid, which forms products upon decomposing in the second stage. A kinetic equation that describes the studied process is offered. The constants of equilibrium of the intermediate complex formation ( K eq) and its decomposition constant ( k 2) in acetone and benzene were calculated. It was shown that the nature of the solvent influences the numerical values of both K p and k 2. It was established that introduction of acetic acid (which is able to form compounds with Py) into the reaction medium slows the rate of the oxidation process drastically. Correlation equations linking the polarity, polarizability, electrophilicity, and basicity of solvents with the constant of the PDA oxidation reaction rate for Py were found. It was concluded that the basicity and polarity of the solvent have a decisive influence on the oxidation reaction rate, while the polarizability and electrophilicity of the reaction medium do not influence the oxidation reaction rate.

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

    PubMed Central

    2014-01-01

    Background 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. Results 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%. Conclusions 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

  19. Classification of wines from five Spanish origin denominations by aromatic compound analysis.

    PubMed

    Sáenz, Cecilia; Cedrón, Trinidad; Cabredo, Susana

    2010-01-01

    Wine is a complex matrix in which aroma compounds play an important role in the characterization of the flavor pattern of a given wine. Twelve volatile compounds were determined in 244 samples of Spanish red wines from different denominations of origin: Rioja, Navarra, Valdepeñas, La Mancha, and Cariñena. The samples were analyzed by GC using headspace solid-phase microextraction. The concentration (mg/mL) intervals obtained were 3-methyl-butyl acetate (3.9 to 116), 3-methyl-1-butanol (93 to 724), ethyl hexanoate (0.8 to 39), 1-hexanol (0.3 to 6.7), ethyl octanoate (1.4 to 41), diethyl succinate (0.2 to 13), 2-phenyl ethyl acetate (0 to 5.3), hexanoic acid (0 to 8.3), geraniol (0 to 3.0), 2-phenylethanol (1.5 to 56), octanoic acid (0 to 20), and decanoic acid (0 to 3.3). Wines were classified by multivariate statistical methods: principal component analysis, and lineal discriminant analysis. A correct differentiation among wines according to their origin was obtained by lineal discriminant analysis. PMID:21313821

  20. Polymerization of olefins employing a catalyst containing a titanium component derived from hydroxyalkyl aromatic compounds

    SciTech Connect

    Coleman, W.M. III; Edmondson, M.S.

    1986-03-18

    A process is described for polymerizing at least one ..cap alpha..-olefin or a mixture of at least one ..cap alpha..-olefin and at least one polymerizable ethylenically unsaturated monomer in the presence of a supported Ziegler-Natta catalyst; the improvement which comprises employing as the transition metal component of such catalyst that which results from reacting (A) at least one titanium compound represented by the formula Ti(OR)/sub X/X/sub 4//sub -X/ wherein each R is independently a hydrocarbyl group having from 1 to about 20 carbon atoms; X is a halogen and x has a value from zero to 4; with (B) at least one compound containing at least one aliphatic hydroxyl group represented by the formula wherein each A is independently a divalent hydrocarbyl group having from 1 to about 10 carbon atoms; is independently hydrogen, a halogen atom, a hydrocarbyl group, a hydrocarbyloxy group or a halogen, nitro or hydrocarbyloxy substituted hydrocarbyl group or a halogen, nitro or hydrocarbyloxy substituted hydrocarbyloxy group, each such hydrocarbyl or hydrocarbyloxy groups having from 1 to about 20 carbon atoms; n' has a value of from 1 to 5, and each x independently has a value of from zero to 4; and wherein components (A) and (B) are employed in quantities which provide a molar ratio of (B):(A) of 0.1:1 to about 10:1.

  1. A fluorescent molecular capsule with a flexible polyaromatic shell for the detection of monoterpene compounds in water.

    PubMed

    Suzuki, Akira; Kondo, Kei; Sei, Yoshihisa; Akita, Munetaka; Yoshizawa, Michito

    2016-02-11

    A new molecular capsule with a flexible fluorescent shell was formed by the quantitative self-complementary assembly of amphiphilic, U-shaped polyaromatic subunits in water. The capsule can fully encapsulate a variety of non-fluorescent monoterpene compounds (e.g., menthone, menthol, and p-menthane) in the hydrophobic cavity and act as a fluorescent supramolecular probe for recognizing the structural identity of the analytes by emissive signals in water at room temperature. PMID:26804491

  2. Bringing Bioactive Compounds into Membranes: The UbiA Superfamily of Intramembrane Aromatic Prenyltransferases.

    PubMed

    Li, Weikai

    2016-04-01

    The UbiA superfamily of intramembrane prenyltransferases catalyzes a key biosynthetic step in the production of ubiquinones, menaquinones, plastoquinones, hemes, chlorophylls, vitamin E, and structural lipids. These lipophilic compounds serve as electron and proton carriers for cellular respiration and photosynthesis, as antioxidants to reduce cell damage, and as structural components of microbial cell walls and membranes. This article reviews the biological functions and enzymatic activities of representative members of the superfamily, focusing on the remarkable recent research progress revealing that the UbiA superfamily is centrally implicated in several important physiological processes and human diseases. Because prenyltransferases in this superfamily have distinctive substrate preferences, two recent crystal structures are compared to illuminate the general mechanism for substrate recognition. PMID:26922674

  3. Aromatic fluorine compounds. X. The 2,3- and 2,6-difluoropyridines

    USGS Publications Warehouse

    Finger, G.C.; Starr, L.D.; Roe, A.; Link, W.J.

    1962-01-01

    The preparation of difluoropyridines by the Schiemann reaction was investigated. 2-Amino-6-fluoropyridine (IIIa), necessary for the synthesis of 2,6-difluoropyridine (IVa) by the Schiemann reaction, was conveniently prepared by the Curtius degradation of 6-fluoropicolinic hydrazide (IIa) and by the Hofmann reaction on 6-fluoropicolinamide (IId). Since an ??-fluorine on a pyridine nucleus is preferentially replaced by hydrazine when it is either adjacent to or opposite a carbomethoxy group, the hydrazides necessary for the synthesis of 3-amino-2- and 6-fluoropyridine could not be prepared. These amines were prepared from the appropriate 2-fluoropyridinecarboxamide by the Hofmann reaction. The preparation of difluoropyridines was successful with two of the aminofluoropyridines and led to the following new compounds: 2,3-difluoro(IVb) and 2,6-difluoropyridine (IVa).

  4. Enhancing the Photostability of Arylvinylenebipyridyl Compounds as Fluorescent Indicators for Intracellular Zinc(II) Ions.

    PubMed

    Yuan, Zhao; Younes, Ali H; Allen, John R; Davidson, Michael W; Zhu, Lei

    2015-06-01

    Arylvinylenebipyridyl (AVB) ligands are bright, zinc(II)-sensitive fluoroionophores. The applicability of AVBs as fluorescent indicators for imaging cellular zinc(II), however, is limited by low photostability, partially attributable to the photoisomerization of the vinylene functionality. Two configurationally immobilized (i.e., "locked") AVB analogues are prepared in this work. The zinc(II)-sensitive photophysical properties and zinc(II) affinities of both AVBs and their locked analogues are characterized in organic and aqueous media. The zinc(II) sensitivity of the emission is attributed to the zinc(II)-dependent energies of the charge transfer excited states of these compounds. The configurationally locked ligands have improved photostability, while maintaining the brightness and zinc(II) sensibility of their AVB progenitors. The feasibility of the "locked" AVB analogues with improved photostability for imaging intracellular Zn(II) of eukaryotic cells using laser confocal fluorescence microscopy is demonstrated. PMID:25942357

  5. Enhancing the Photostability of Arylvinylenebipyridyl Compounds as Fluorescent Indicators for Intracellular Zinc(II) Ions

    PubMed Central

    Yuan, Zhao; Younes, Ali H.; Allen, John R.; Davidson, Michael W.; Zhu, Lei

    2015-01-01

    Arylvinylenebipyridyl (AVB) ligands are bright, zinc(II)-sensitive fluoroionophores. The applicability of AVBs as fluorescent indicators for imaging cellular zinc(II), however, is limited by low photostability, partially attributable to the photoisomerization of the vinylene functionality. Two configurationally immobilized (i.e., “locked”) AVB analogues are prepared in this work. The zinc(II)-sensitive photophysical properties and zinc(II) affinities of both AVBs and their locked analogues are characterized in organic and aqueous media. The zinc(II) sensitivity of the emission is attributed to the zinc(II)-dependent energies of the charge transfer excited states of these compounds. The configurationally locked ligands have improved photostability, while maintaining the brightness and zinc(II) sensibility of their AVB progenitors. The feasibility of the “locked” AVB analogues with improved photostability for imaging intracellular Zn(II) of eukaryotic cells using laser confocal fluorescence microscopy is demonstrated. PMID:25942357

  6. Comparing Urinary Biomarkers of Airborne and Dermal Exposure to Polycyclic Aromatic Compounds in Asphalt-Exposed Workers

    PubMed Central

    Sobus, Jon R.; McClean, Michael D.; Herrick, Robert F.; Waidyanatha, Suramya; Nylander-French, Leena A.; Kupper, Lawrence L.; Rappaport, Stephen M.

    2009-01-01

    When working with hot mix asphalt, road pavers are exposed to polycyclic aromatic hydrocarbons (PAHs) through the inhalation of vapors and particulate matter (PM) and through dermal contact with PM and contaminated surfaces. Several PAHs with four to six rings are potent carcinogens which reside in these particulate emissions. Since urinary biomarkers of large PAHs are rarely detectable in asphalt workers, attention has focused upon urinary levels of the more volatile and abundant two-ring and three-ring PAHs as potential biomarkers of PAH exposure. Here, we compare levels of particulate polycyclic aromatic compounds (P-PACs, a group of aromatic hydrocarbons containing PAHs and heterocyclic compounds with four or more rings) in air and dermal patch samples from 20 road pavers to the corresponding urinary levels of naphthalene (U-Nap) (two rings), phenanthrene (U-Phe) (three rings), monohydroxylated metabolites of naphthalene (OH-Nap) and phenanthrene (OH-Phe), and 1-hydroxypyrene (OH-Pyr) (four rings), the most widely used biomarker of PAH exposure. For each worker, daily breathing-zone air (n = 55) and dermal patch samples (n = 56) were collected on three consecutive workdays along with postshift, bedtime, and morning urine samples (n = 149). Measured levels of P-PACs and the urinary analytes were used to statistically model exposure–biomarker relationships while controlling for urinary creatinine, smoking status, age, body mass index, and the timing of urine sampling. Levels of OH-Phe in urine collected postshift, at bedtime, and the following morning were all significantly associated with levels of P-PACs in air and dermal patch samples. For U-Nap, U-Phe, and OH-Pyr, both air and dermal patch measurements of P-PACs were significant predictors of postshift urine levels, and dermal patch measurements were significant predictors of bedtime urine levels (all three analytes) and morning urine levels (U-Nap and OH-Pyr only). Significant effects of

  7. Headspace in-tube microextraction coupled with micellar electrokinetic chromatography of neutral aromatic compounds.

    PubMed

    Cho, Sung Min; Park, Bum Su; Jung, Woo Sung; Lee, Sang Won; Jung, Yunhwan; Chung, Doo Soo

    2016-02-01

    Headspace (HS) extraction can be carried out easily and aptly via single drop microextraction coupled with capillary electrophoresis (CE). However, one drawback is the difficulty of keeping the single drop stably at the capillary tip. To solve this problem, we have recently demonstrated HS in-tube microextraction (ITME) of acidic compounds such as chlrophenols in an acidic sample using a basic run buffer plug in the separation capillary for CE as an acceptor phase. In this report, an organic acceptor plug in a capillary was used to extract neutral organic volatile pollutants such as BTEX (benzene, toluene, ethylbenzene, and m-xylene). After extraction, the analytes enriched in the organic acceptor plug were analyzed with micellar electrokinetic chromatography (MEKC). The enrichment factors for BTEX in a standard solution were up to 350 under an optimal condition of 25°C for 20 min. As an application, BTEX spiked into bottled water were analyzed with HS-ITME-MEKC, and the enrichment factors for BTEX were up to 320. The limits of detections were 1-4 ppb, which are at least 200 times lower than the US Environmental Protection Agency guidelines for drinking water, except benzene. The entire procedure of HS-ITME-MEKC was carried out automatically using a commercial CE instrument. PMID:26653509

  8. Mutants of Pseudomonas cepacia G4 defective in catabolism of aromatic compounds and trichloroethylene.

    PubMed Central

    Shields, M S; Montgomery, S O; Cuskey, S M; Chapman, P J; Pritchard, P H

    1991-01-01

    Pseudomonas cepacia G4 possesses a novel pathway of toluene catabolism that is shown to be responsible for the degradation of trichloroethylene (TCE). This pathway involves conversion of toluene via o-cresol to 3-methylcatechol. In order to determine the enzyme of toluene degradation that is responsible for TCE degradation, chemically induced mutants, blocked in the toluene ortho-monooxygenase (TOM) pathway of G4, were examined. Mutants of the phenotypic class designated TOM A- were all defective in their ability to oxidize toluene, o-cresol, m-cresol, and phenol, suggesting that a single enzyme is responsible for conversion of these compounds to their hydroxylated products (3-methylcatechol from toluene, o-cresol, and m-cresol and catechol from phenol) in the wild type. Mutants of this class did not degrade TCE. Two other mutant classes which were blocked in toluene catabolism, TOM B-, which lacked catechol-2,3-dioxygenase, and TOM C-, which lacked 2-hydroxy-6-oxoheptadienoic acid hydrolase activity, were fully capable of TCE degradation. Therefore, TCE degradation is directly associated with the monooxygenation capability responsible for toluene, cresol, and phenol hydroxylation. PMID:1892384

  9. Integrated anaerobic-aerobic process for the biodegradation of chlorinated aromatic compounds

    SciTech Connect

    Armenante, P.M.; Lewandowski, G.; Chengming Kung ); Kafkewitz, D. )

    1992-05-01

    An integrated anaerobic-aerobic process for the complete mineralization of 2,4,6-trichlorophenol was successfully tested and operated. The sludge obtained from the anaerobic digester of a commercial treatment plant was used to obtain an anaerobic consortium capable of partially dechlorinating 2,4,6-trichlorophenol (2,4,6-TCP). The clarified and sterilized effluent from the same anaerobic digester was used as the medium for the anaerobic consortium. During the anaerobic process 2,4,6-TCP was first dechlorinated to 2,4-dichlorophenol and then to 4-chlorophenol (4CP). Stoichiometric amounts of 4-CP were recovered. Similar results were obtained when the anaerobic microorganisms were immobilized on Manville R-635 silica beads. After immobilization, the consortium was able to dechlorinate 150{mu}M of 2,4,6-TCP in four days. Pseudomonas Glathei and an indigenous culture obtained from same sludge used to produce the anaerobic enrichment culture were shown to be able to degrade the 4-CP produced from the anaerobic dechlorination of 2,4,6-TCP. However, for the aerobic 4-CP mineralization to occur the medium had to be buffered with phosphate, since high pH would inhibit the aerobic bacterial activity. It is expected that the proposed approach will be used to treat recalcitrant halogenated compounds that are not amenable to conventional biological treatment.

  10. Limiting activity coefficients of some aromatic and aliphatic nitro compounds in water

    SciTech Connect

    Benes, M.; Dohnal, V.

    1999-09-01

    Limiting activity coefficients of nine nitroaromatic compounds and four nitroalkanes in water were determined in the range of environmentally related temperatures by measuring suitable phase equilibria. For liquid and solid nitroaromatics (nitrobenzene, 2-nitrotoluene, 3-nitrotoluene, 4-nitrotoluene, 2-nitrophenol, 3-nitrophenol, 4-nitrophenol, 1-chloro-2-nitrobenzene, and 1-chloro-4-nitrobenzene) the aqueous solubilities were measured by a conventional batch contacting method with UV spectrophotometric analysis, while for nitroalkanes (nitromethane, nitroethane, 1-nitropropane, and 2-nitropropane) the air-water partitioning (Henry`s law constant H{sub 12} or air-water partition coefficient K{sub aw}) was determined by the inert gas stripping method employing gas chromatography. Whenever possible, results were compared to literature values. Calculation of H{sub 12} or K{sub aw} for nitroaromatics from the measured solubilities is hindered by the lack of reliable vapor pressure data. On the basis of the temperature dependences of the solubilities measured, the enthalpies of solution at infinite dilution for the nitroaromatics in water were evaluated.

  11. Titanium-containing mesoporous molecular sieves for catalytic oxidation of aromatic compounds

    NASA Astrophysics Data System (ADS)

    Tanev, Peter T.; Chibwe, Malama; Pinnavaia, Thomas J.

    1994-03-01

    TITANIUM silicalite is an effective molecular-sieve catalyst for the selective oxidation of alkanes, the hydroxylation of phenol and the epoxidation of alkenes in the presence of H2O2 (refs 1-3). The range of organic compounds that can be oxidized is greatly limited, however, by the relatively small pore size (about 0.6 nm) of the host framework4. Large-pore (mesoporous) silica-based molecular sieves have been prepared recently by Kresge et all5-7 and Kuroda et al 8.; the former used a templating approach in which the formation of an inorganic mesoporous structure is assisted by self-organization of surfactants, and the latter involved topochemical rearrangement of a layered silica precursor. Here we describe the use of the templating approach to synthesize mesoporous silica-based molecular sieves partly substituted with titanium-large-pore analogues of titanium silicalite. We find that these materials show selective catalytic activity towards the oxidation of 2,6-ditert-butyl phenol to the corresponding quinone and the conversion of benzene to phenol.

  12. A simple, comprehensive, and miniaturized solvent extraction method for determination of particulate-phase polycyclic aromatic compounds in air.

    PubMed

    Santos, Aldenor G; Regis, Ana Carla D; da Rocha, Gisele O; Bezerra, Marcos de A; de Jesus, Robson M; de Andrade, Jailson B

    2016-02-26

    The method allowed simultaneous characterization of PAHs, nitro-PAHs and quinones in atmospheric particulate matter. This method employs a miniaturized micro-extraction step that uses 500μL of an acetonitrile-dichloromethane mix and instrumental analysis by means of a high-resolution GC-MS. The method was validated using the SRM1649b NIST standard reference material as well as deuterated internal standards. The results are in good agreement with the certified values and show recoveries between 75% and 145%. Limit of detection (LOD) values for PAHs were found to be between 0.5pg (benzo[a]pyrene) to 2.1pg (dibenzo[a,h]anthracene), for nitro-PAHs ranged between 3.2pg (1-nitrobenzo[e]pyrene) and 22.2pg (3-nitrophenanthrene), and for quinones ranged between 11.5pg (1,4-naphthoquinone) and 458pg (9,10-phenanthraquinone). The validated method was applied to real PM10 samples collected on quartz fiber filters. Concentrations in the PM10 samples ranged from 0.06 to 15ngm(-3) for PAHs, fromaromatic compounds in airborne particles from both polluted and non-polluted atmospheres. PMID:26830633

  13. Polycyclic aromatic hydrocarbons (PAHs), nitro-PAHs and related environmental compounds: biological markers of exposure and effects.

    PubMed Central

    Talaska, G; Underwood, P; Maier, A; Lewtas, J; Rothman, N; Jaeger, M

    1996-01-01

    Lung cancer caused by polycyclic aromatic hydrocarbons (PAHs), nitro-PAHs and related environmental agents is a major problem in industrialized nations. The high case-fatality rate of the disease, even with the best supportive treatment, underscores the importance of primary lung cancer prevention. Development of biomarkers of exposure and effects to PAHs and related compounds is now underway and includes measurement of urinary metabolites of specific PAHs as well as detection of protein and DNA adducts as indicators of effective dose. Validation of these markers in terms of total environmental dose requires that concurrent measures of air levels and potential dermal exposure be made. In addition, the interrelationships between PAH biomarkers must be determined, particularly when levels of the marker in surrogate molecules (e.g., protein) or markers from surrogate tissues (e.g., lymphocyte DNA) are used to assess the risk to the target organ, the lung. Two approaches to biomarker studies will be reviewed in this article: the progress made using blood lymphocytes as surrogates for lung tissues and the progress made developing noninvasive markers of carcinogen-DNA adduct levels in lung-derived cells available in bronchial-alveolar lavage and in sputum. Data are presented from studies in which exfoliated urothelial cells were used as a surrogate tissue to assess exposure to human urinary bladder carcinogens in occupational groups. PMID:8933032

  14. Metagenomic Analysis of the Pygmy Loris Fecal Microbiome Reveals Unique Functional Capacity Related to Metabolism of Aromatic Compounds

    PubMed Central

    Xu, Bo; Xu, Weijiang; Yang, Fuya; Li, Junjun; Yang, Yunjuan; Tang, Xianghua; Mu, Yuelin; Zhou, Junpei; Huang, Zunxi

    2013-01-01

    The animal gastrointestinal tract contains a complex community of microbes, whose composition ultimately reflects the co-evolution of microorganisms with their animal host. An analysis of 78,619 pyrosequencing reads generated from pygmy loris fecal DNA extracts was performed to help better understand the microbial diversity and functional capacity of the pygmy loris gut microbiome. The taxonomic analysis of the metagenomic reads indicated that pygmy loris fecal microbiomes were dominated by Bacteroidetes and Proteobacteria phyla. The hierarchical clustering of several gastrointestinal metagenomes demonstrated the similarities of the microbial community structures of pygmy loris and mouse gut systems despite their differences in functional capacity. The comparative analysis of function classification revealed that the metagenome of the pygmy loris was characterized by an overrepresentation of those sequences involved in aromatic compound metabolism compared with humans and other animals. The key enzymes related to the benzoate degradation pathway were identified based on the Kyoto Encyclopedia of Genes and Genomes pathway assignment. These results would contribute to the limited body of primate metagenome studies and provide a framework for comparative metagenomic analysis between human and non-human primates, as well as a comparative understanding of the evolution of humans and their microbiome. However, future studies on the metagenome sequencing of pygmy loris and other prosimians regarding the effects of age, genetics, and environment on the composition and activity of the metagenomes are required. PMID:23457582

  15. Comparative study on catalytic hydrodehalogenation of halogenated aromatic compounds over Pd/C and Raney Ni catalysts

    NASA Astrophysics Data System (ADS)

    Ma, Xuanxuan; Liu, Sujing; Liu, Ying; Gu, Guodong; Xia, Chuanhai

    2016-04-01

    Catalytic hydrodehalogenation (HDH) has proved to be an efficient approach to dispose halogenated aromatic compounds (HACs). Liquid-phase HDH of single and mixed halobenzenes/4-halophenols with H2 over 5% Pd/C and Raney Ni catalyst are investigated and compared. For liquid-phase HDH of single HACs, hydrogenolytic scission reactivity of C-X bonds decreases in order of C-Br > C-Cl > C-I > C-F over Pd/C catalyst, and in order of C-I > C-Br > C-Cl > C-F over Raney Ni catalyst. To clarify the reason why hydrogenolytic scission reactivity of C-X bonds over Pd/C and Raney Ni catalysts exhibits different trends, liquid-phase HDH of mixed HACs over Pd/C and Raney Ni catalysts were studied, and catalysts are characterized by SEM, EDX, and XRD techniques. It was found that the high adsorption of iodoarenes on Pd/C catalyst caused the HDH reactivity of iodoarenes to be lower than that of chloroarenes and bromoarenes in the HDH of single HACs. Moreover, the adsorption of in situ produced iodine ion (I‑) to catalyst surface would result in the decline of catalytic activity, which might be the main reason why the HDH reactivity of HACs in the presence of NaI is rather low.

  16. Simultaneous evaluation of polycyclic aromatic hydrocarbons and carbonyl compounds in the atmosphere of Niterói City, RJ, Brazil

    NASA Astrophysics Data System (ADS)

    Franco, Caroline Fernandes Jaegger; de Mendonça Ochs, Soraya; de Oliveira Grotz, Lucas; de Almeida Furtado, Leonardo; Pereira Netto, Annibal Duarte

    2015-04-01

    Atmospheric particulate matter (total suspended particulate - TSP - and inhalable particles - PM10) and gas-phase samples were collected in three periods of seven to nine consecutive days in June and December 2011, and May 2012, in the central area of Niterói City, Rio de Janeiro State, Brazil. TSP (48.8-214 μg m-3) showed higher concentrations than PM10 (nd - 82.6 μg m-3). Sixteen polycyclic aromatic hydrocarbons (PAH) and thirty-one carbonyl compounds (CC) were evaluated. Concentrations of individual PAH ranged from

  17. Isolation and Characterization of a Subsurface Bacterium Capable of Growth on Toluene, Naphthalene, and Other Aromatic Compounds

    PubMed Central

    Fredrickson, J. K.; Brockman, F. J.; Workman, D. J.; Li, S. W.; Stevens, T. O.

    1991-01-01

    A bacterium, designated F199, utilized toluene, naphthalene, dibenzothiophene, salicylate, benzoate, p-cresol, and all isomers of xylene as a sole carbon and energy source. This bacterium was isolated from Middendorf sediments, a Cretaceous age formation that underlies the Southeast Coastal Plain in South Carolina, at a depth of approximately 410 m. F199 is a gram-positive, irregular-shaped bacterium that has a varied cell morphology that is dependent on culture medium type and growth stage. F199 required microaerobic conditions (40 to 80 μM O2) for growth on hydrocarbons, glucose, acetate, and lactate in mineral salts medium but not for growth on rich media. [14C]naphthalene mineralization by F199 was induced by either naphthalene or toulene; however, [14C]toluene mineralization by this strain was induced by toluene but not naphthalene. F199 was also found to harbor two plasmids larger than 100 kb. Restricted F199 plasmid and genomic DNA did not hybridize with toluene (pWW0) or naphthalene (NAH7) catabolic plasmid DNA probes. The presence in the Middendorf formation of bacteria with the capacity for degrading a variety of aromatic compounds suggests that indigenous microorganisms may have potential for in situ degradation of organic contaminants. Images PMID:16348445

  18. Catalytic effects by metal oxides on the formation and degradation of chlorinated aromatic compounds in fly ash.

    PubMed

    Oberg, T; Bergbäck, B; Filipsson, M

    2008-04-01

    Polychlorinated benzenes, dibenzo-p-dioxins (PCDD), and dibenzofurans (PCDF) may be formed below the combustion temperature in fly ash from municipal solid waste incinerators (MSWI). Copper catalyzes this formation, possibly by the Deacon reaction. Many other elements are also Deacon catalysts or promoters, and here we report results from a statistically designed experiment with 15 metal oxides added to fly ash and heated at 300 degrees C for 2h in an air atmosphere. A resolution IV fractional factorial design with four replicates was completed in 36 runs with the oxides of magnesium, yttrium, titanium, vanadium, niobium, chromium, molybdenum, tungsten, manganese, iron, cobalt, nickel, copper, zinc, and tin. All samples were analyzed for chlorinated benzenes and the results were evaluated by analysis of variance. The addition of copper significantly increased the amounts of the chlorinated benzenes, while cobalt, chromium and vanadium decreased the net formation. The oxides of zinc and iron seemed to have a slightly positive and negative effect respectively. The findings in this study seem to corroborate our previously reported results regarding the different catalytic effects of copper and chromium, and lack of a significant effect by nickel. Besides chromium, it also identifies cobalt and vanadium as potent catalysts for oxidative degradation of the chlorinated aromatic compounds found in MSWI fly ash. PMID:18061236

  19. Comparative study on catalytic hydrodehalogenation of halogenated aromatic compounds over Pd/C and Raney Ni catalysts

    PubMed Central

    Ma, Xuanxuan; Liu, Sujing; Liu, Ying; Gu, Guodong; Xia, Chuanhai

    2016-01-01

    Catalytic hydrodehalogenation (HDH) has proved to be an efficient approach to dispose halogenated aromatic compounds (HACs). Liquid-phase HDH of single and mixed halobenzenes/4-halophenols with H2 over 5% Pd/C and Raney Ni catalyst are investigated and compared. For liquid-phase HDH of single HACs, hydrogenolytic scission reactivity of C-X bonds decreases in order of C-Br > C-Cl > C-I > C-F over Pd/C catalyst, and in order of C-I > C-Br > C-Cl > C-F over Raney Ni catalyst. To clarify the reason why hydrogenolytic scission reactivity of C-X bonds over Pd/C and Raney Ni catalysts exhibits different trends, liquid-phase HDH of mixed HACs over Pd/C and Raney Ni catalysts were studied, and catalysts are characterized by SEM, EDX, and XRD techniques. It was found that the high adsorption of iodoarenes on Pd/C catalyst caused the HDH reactivity of iodoarenes to be lower than that of chloroarenes and bromoarenes in the HDH of single HACs. Moreover, the adsorption of in situ produced iodine ion (I−) to catalyst surface would result in the decline of catalytic activity, which might be the main reason why the HDH reactivity of HACs in the presence of NaI is rather low. PMID:27113406

  20. Influence of the surface structure of graphene oxide on the adsorption of aromatic organic compounds from water.

    PubMed

    Yan, Han; Wu, Hu; Li, Kun; Wang, Yawen; Tao, Xue; Yang, Hu; Li, Aimin; Cheng, Rongshi

    2015-04-01

    In this work, graphene oxide (GO) has been employed as an efficient adsorbent for the removal of three aromatic organic compounds (AOCs), namely, aniline, nitrobenzene, and chlorobenzene, from water under various initial AOC concentrations and pH levels. Based on the characteristics of surface structures of GO, a simple semiquantitative model has been provided to describe the intrinsic adsorption behavior of GO to AOCs. Accordingly, the adsorption mechanism has been discussed in detail at molecular levels. The contribution coefficients derived from the proposed model indicate that the most preferential interactions between GO and AOCs are hydrophobic interactions (π-π stacking and hydrophobic effect) that occur on graphitic zones of GO (unoxidized region). In the oxidized region, there also exist the hydrophobic interactions on sp(2) clusters, although they may be hindered by surrounding sp(3) zones which are the most unfavorable and are only accessible to AOCs through hydrogen bonding or electrostatic effects. More interestingly, aniline exhibits the highest contribution coefficients in both hydrophobic and hydrophilic zones of GO among the three measured AOCs due to its good water solubility and facile formation of hydrogen bonds. Furthermore, the analytical results of the adsorption isotherms are also fully consistent with those from the proposed model. PMID:25764972

  1. Fragmentation pathways and mechanisms of aromatic compounds in atmospheric pressure studied by GC-DMS and DMS-MS

    NASA Astrophysics Data System (ADS)

    Kendler, Shai; Lambertus, Gordon R.; Dunietz, Barry D.; Coy, Stephen L.; Nazarov, Erkinjon G.; Miller, Raanan A.; Sacks, Richard D.

    2007-06-01

    Differential mobility spectrometry (DMS) is a highly sensitive sensing technology capable of selecting and detecting ions based on the difference between ion mobility at high and low electric field. The combination of a micro-fabricated DMS with gas chromatography (GC) has allowed extensive investigation of the ion chemistry and collisionally induced dissociation (CID) of diaryl molecules on a millisecond timescale at temperatures up to 130 °C. DMS-pre-filtered time-of-flight mass spectrometry (DMS-MS) has been used to verify the chemical composition of the ion species resolved by GC-DMS. This work focuses on the fragmentation of diaryl compounds, including diphenyl methane (DPM) and bibenzyl (BB), using information from the DMS and DMS-MS spectra of a series of aromatic compounds. Density functional theory calculations have been used to investigate the geometry and the energy along the reaction coordinate for the loss of benzene from DPM·H+ and BB·H+ for comparison with GC-DMS and DMS-MS experimental results and with previously reported chemical ionization MS. DPM-H+ is observed to undergo field-induced fragmentation in the DMS to produce C7H7+(Bz+) and unobserved neutral benzene with a low energy barrier. In contrast, BB·H+ fragments to C8H9+ and benzene with a higher energy barrier. Calculated barriers and experimental results are in qualitative agreement. Depletion of the ionized fragments in favor of ion-neutral clusters was also observed at higher concentrations. It is suggested that CID in DMS can further enhance DMS analytical performance.

  2. Unusual high fluorescence of two nitro-distyrylbenzene-like compounds induced by CT processes affecting the fluorescence/intersystem-crossing competition.

    PubMed

    Carlotti, B; Elisei, F; Mazzucato, U; Spalletti, A

    2015-06-14

    Two nitro-substituted 1,4-distyrylbenzene-like compounds have been investigated using stationary and time-resolved (ns/fs) spectrometric techniques as a function of solvent polarity. In the two compounds the central benzene ring is substituted with a p-nitrostyryl group at one side while, at the other side, compound 1 (asymmetric) bears a pyrid-4-ylethenyl group and compound 2 (symmetric) another p-nitrostyryl group. The solvent dependent intramolecular charge transfer (ICT) in the singlet manifold was found to strongly affect the competition among fluorescence, intersystem crossing and trans-cis photoisomerization. The presence of nitro-groups in the 1,4-distyrylbenzene skeleton causes the usual strong decrease of fluorescence in favour of intersystem crossing to a reactive triplet state. However, the favoured formation of the ICT state in polar solvents induces an unexpected important increase of the fluorescence quantum yield (three/two order of magnitude for the nitro and dinitro derivatives, respectively). The ultrafast spectral transients helped to understand the solvent effects measured by stationary techniques and gave information on the dynamics of the locally excited singlet state ((1)LE*) and the (1)ICT* state, fast produced in polar solvents. Evidence of dual fluorescence in a limited range of solvent polarity, particularly for compound 1, is also reported. The role of an upper triplet state in a non-polar solvent is discussed also based on quantum-mechanical calculations (TD-DFT method) and temperature effects on the photophysical parameters. PMID:25975235

  3. Separation-oriented derivatization of native fluorescent compounds through fluorous labeling followed by liquid chromatography with fluorous-phase.

    PubMed

    Sakaguchi, Yohei; Yoshida, Hideyuki; Todoroki, Kenichiro; Nohta, Hitoshi; Yamaguchi, Masatoshi

    2009-06-15

    We have developed a new and simple method based on "fluorous derivatization" for LC of native fluorescent compounds. This method involves the use of a column with a fluorous stationary phase. Native fluorescent analytes with target functional groups are precolumn derivatized with a nonfluorescent fluorous tag, and the fluorous-labeled analytes are retained in the column, whereas underivatized substances are not. Only the retained fluorescent analytes are detected fluorometrically at appropriate retention times, and retained substrates without fluorophores are not detected. In this study, biologically important carboxylic acids (homovanillic acid, vanillylmandelic acid, and 5-hydroxyindoleacetic acid) and drugs (naproxen, felbinac, flurbiprofen, and etodolac) were used as model native fluorescent compounds. Experimental results indicate that the fluorous-phase column can selectively retain fluorous compounds including fluorous-labeled analytes on the basis of fluorous separation. We believe that separation-oriented derivatization presented here is the first step toward the introduction of fluorous derivatization in quantitative LC analysis. PMID:19459682

  4. Rapid determination of trace polycyclic aromatic hydrocarbons in particulate matter using accelerated solvent extraction followed by ultra high performance liquid chromatography with fluorescence detection.

    PubMed

    Xu, Tianci

    2016-05-01

    A method has been developed for the trace analysis of polycyclic aromatic hydrocarbons, which are known as persistent organic pollutants and ubiquitous constituents of fine particulate matter that causes growing airborne pollution. The method, which was especially for samples of airborne particulate matter less than 2.5 μm in diameter, utilized accelerated solvent extraction and ultra high performance liquid chromatography with fluorescence detector. Four principal parameters of accelerated solvent extraction were optimized to obtain maximum extraction efficiency. Using the established synergetic programs of gradient elution and fluorescence wavelength switching, a rapid separation was achieved in 6.56 min with good linearity for 15 polycyclic aromatic hydrocarbons (coefficient of determination above 0.999). The limits of detection ranged from 0.833 to 10.0 pg/m(3) . The precision of the method expressed as inter-day relative standard deviation ranged from 0.2 to 1%, which was calculated from nine repetitive measurements of 8.00 μg/L analytes. Average spiked recoveries ranged from 71.6 to 97.7%, with the exception of naphthalene. The rapid, sensitive, and accurate method can meet the pressing needs of health risk assessment and increasingly heavy daily tasks of air quality monitoring. PMID:26991966

  5. Micro x-ray fluorescence as a high throughput screening method for metal chelating compounds

    NASA Astrophysics Data System (ADS)

    Minogue, Edel M.; Havrilla, George J.; Taylor, Tammy P.; Burrell, Anthony K.; Warner, Benjamin P.

    2005-06-01

    Micro X-ray Fluorescence (MXRF) has proven to be a powerful tool in the rapid and quantitative means of screening oliogpeptides. MXRF is a non-destructive method of analysis, which can detect elemental composition of a sample by measuring its characteristic X-ray emission wavelengths or energies. An effective high throughput screening technique is described for the rapid screening of bead-based libraries by MXRF in order to identify suitable chelating agents that will bind metals found in radioactive dispersive devices. It is a sensitive technique which in conjunction with the wide range of chemistry inherent in peptide libraries (e.g. varying charge, length, hydrophobicity, aromaticity etc.), provides a rapid and quantitative means for screening chelator-ion binding. The method involves the selection of a suitable library of ligands; in this case it is a bead-based library of peptides. The library is exposed to the cation of interest and immobilized on to a microarray. The array is then analyzed by MXRF enabling rapid identification of chelating agents. This enables the screening of approximately 27,500 sequences per day. Initial experiments carried out successfully identified sequences that are selective for Co under certain binding conditions. This involved the screening of 8,400 sequences in adverse environmental conditions containing possible interferences (e.g. Ca, Fe, Al, Cs, Ir), which could be encountered in our application.

  6. Spectroscopic Evidence of Anthropogenic Compounds Extraction from Polymers by Fluorescent Dissolved Organic Matter in Natural Water

    NASA Astrophysics Data System (ADS)

    Miranda, M.; Trojzuck, A.; Voss, D.; Gassmann, S.; Zielinski, O.

    2016-04-01

    FDOM is one of the most important carriers of anthropogenic compounds in natural waters. It can combine with environmental contaminants and polymers to form diverse chemical structures. To this end, here a microfluidic chip was designed for the analysis of these changes in fluorescent dissolved organic matter (FDOM) fingerprints due to thermal treatment and varying time intervals of exposure. Excitation Emission Matrix Spectroscopy (EEMS) approach was utilized to detect and identify the inherent compounds in sampled FDOM. Strong direct correlations were founded, Spearman rank correlation values (ρ = 0.85 at α = 0.1, n = 4) and linear correlation R2 = 0.8359 were noted between thermal treatment pattern 2 and fluorescence intensity of samples. Materials, acrylic based glue and cyclic olefin copolymer (COC) polymer, used to design the microfluidic sensor were determined to possess unique spectral features in the ultraviolet to green spectrum using EEMS. The study therefore provides an insight on methods to identify contaminants in natural waters. This underlines the potential of optical sensors providing measurements at fast intervals, enabling environmental monitoring.

  7. Regulation of glutathione S-transferase Ya subunit gene expression: identification of a unique xenobiotic-responsive element controlling inducible expression by planar aromatic compounds.

    PubMed Central

    Rushmore, T H; King, R G; Paulson, K E; Pickett, C B

    1990-01-01

    We have identified a region in the 5' flanking sequence of the glutathione S-transferase (RX:glutathione R-transferase, EC 2.5.1.18) Ya subunit gene that contains a unique xenobiotic-responsive element (XRE). The regulatory region spans nucleotides -722 to -682 of the 5' flanking sequence and is responsible for part of the basal level as well as inducible expression of the Ya subunit gene by planar aromatic compounds such as beta-naphthoflavone (beta-NF) and 3-methyl-cholanthrene. The DNA sequence of this region (beta-NF-responsive element) is distinct from the DNA sequence of the XRE found in the cytochrome P-450 IA1 gene. In addition to the region containing the beta-NF-responsive element, two other regulatory regions of the Ya subunit gene have been identified. One region spans nucleotides -867 to -857 and has a DNA sequence with identity to the hepatocyte nuclear factor 1 recognition motif found in several liver-specific genes. The second region spans nucleotides -908 to -899 and contains a DNA sequence with identity to the XRE found in the cytochrome P-450 IA1 gene. The XRE sequence also contributes to part of the responsiveness of the Ya subunit gene to planar aromatic compounds. Our data suggest that regulation of gene expression by planar aromatic compounds can be mediated by a DNA sequence that is distinct from the XRE sequence. Images PMID:2160079

  8. Spectroscopic evidence of xanthine compounds fluorescence quenching effect on water-soluble porphyrins

    NASA Astrophysics Data System (ADS)

    Makarska-Bialokoz, Magdalena

    2015-02-01

    The formation of π-stacked complexes between water-soluble porphyrins: 4,4‧,4″,4″‧-(21H,23H-porphine-5,10,15,20-tetrayl)tetrakis-(benzoic acid) (H2TCPP), 5,10,15,20-tetrakis(4-sulfonatophenyl)-21H,23H-porphine (H2TPPS4), 5,10,15,20-tetrakis[4-(trimethylammonio)phenyl]-21H,23H-porphine tetra-p-tosylate (H2TTMePP), 5,10,15,20-tetrakis(1-methyl-4-pyridyl)-21H,23H-porphine tetra-p-tosylate (H2TMePyP), the Cu(II) complexes of H2TTMePP and H2TMePyP, as well as chlorophyll a with xanthine, theophylline (1,3-dimethylxanthine) and theobromine (3,7-dimethylxanthine) has been studied analysing their absorption and steady-state fluorescence spectra in aqueous (or acetone in case of chlorophyll a) solution. During titration by the compounds from xanthine group the bathochromic effect in the porphyrin absorption spectra as well as the hypochromicity of the porphyrin Soret maximum can be noticed. The fluorescence quenching effect observed during interactions in the systems examined suggests the process of static quenching. The association and fluorescence quenching constants are of the order of magnitude of 103 - 102 mol-1. The results obtained show that xanthine and its derivatives can quench the fluorescence of the porphyrins according to the number of methyl groups in the molecule of quencher.

  9. Pyrolysis of simple coal model compounds containing aromatic carboxylic acids: Does decarboxylation lead to cross-linking?

    SciTech Connect

    Eskay, T.P.; Britt, P.F.; Buchanan, A.C. III

    1996-12-31

    In recent years, it has been proposed that oxygen functional groups, prevalent in low rank coals, are major actors in retrograde reactions which inhibit their efficient thermochemical processing. In the pyrolysis and liquefaction of low-rank coals, low temperature cross-linking reactions have been correlated with the loss of carboxyl groups and the evolution of CO{sub 2} and H{sub 2}O. Pretreatments such as methylation, demineralization, or ion-exchange of the inorganic cations reduce cross-linking and CO{sub 2} evolution in pyrolysis, while the exchange of Na{sup +}, K{sup +}, Ca{sup ++}, and Ba{sup ++} into demineralized coal increases cross-linking and CO{sub 2} evolution in pyrolysis and liquefaction. These results suggest, in part, that decarboxylation pathways in coal may play an important role in the cross-linking of the coal polymer. However, the reaction pathways associated with the decarboxylation and cross-linking events in low rank coal are currently unknown. Furthermore, it is not known whether the reaction pathway that leads to decarboxylation also leads to cross-linking. Radical recombination or addition reactions have been suggested as being involved in retrograde reactions. However, the involvement of radical pathways in thermal decarboxylation reactions has recently been brought into question by the observation that decarboxylation of benzoic acid derivatives under coal liquefaction conditions yielded only small amounts of aryl-aryl coupling products. Therefore, to gain a better understanding of the role decarboxylation plays in cross-linking reactions in low rank coals, we have studied the pyrolysis of several bibenzyls containing aromatic carboxylic acids. The structures currently under investigation are 1,2-(3,3`-dicarboxyphenyl)ethane (1) and 1,2-(4,4`-dicarboxyphenyl)ethane(2). These compounds are capable of forming reactive free-radical intermediates at ca. 400{degrees}C through homolysis of the weak bibenzylic bonds.

  10. Temporal variation in the deposition of polycyclic aromatic compounds in snow in the Athabasca Oil Sands area of Alberta.

    PubMed

    Manzano, Carlos A; Muir, Derek; Kirk, Jane; Teixeira, Camilla; Siu, May; Wang, Xiaowa; Charland, Jean-Pierre; Schindler, David; Kelly, Erin

    2016-09-01

    Atmospheric deposition of polycyclic aromatic compounds (PACs) via and onto snow, and their releasing during spring snowmelt has been a concern in the Athabasca Oil Sands Region of Alberta. This study was designed to evaluate the concentrations, loadings, and distribution of PACs in springtime snowpack and how they have changed since the first study in 2008. Snowpack samples were collected in late winters 2011-2014 at varying distances from the main developments. PAC concentration and deposition declined exponentially with distance, with pyrenes, chrysenes, and dibenzothiophenes dominating the distribution within the first 50 km. The distribution of PACs was different between sites located close to upgraders and others located close to mining facilities. Overall, PAC loadings were correlated with priority pollutant elements and water chemistry parameters, while wind direction and speed were not strong contributors to the variability observed. Total PAC mass deposition during winter months and within the first 50 km was initially estimated by integrating the exponential decay function fitted through the data using a limited number of sites from 2011 to 2014: 1236 kg (2011), 1800 kg (2012), 814 kg (2013), and 1367 (2014). Total loadings were estimated to have a twofold increase between 2008 and 2014, although the increase observed was not constant. Finally, kriging interpolation is presented as an alternative and more robust approach to estimate PAC mass deposition in the area. After a more intensive sampling campaign in 2014, the PAC mass deposition was estimated to be 1968 kg. PMID:27581009

  11. A comparison of concentrations of polycyclic aromatic compounds detected in dust samples from various regions of the world.

    PubMed

    Naspinski, Christine; Lingenfelter, Rebecca; Cizmas, Leslie; Naufal, Ziad; He, Ling Yu; Islamzadeh, Arif; Li, Zhiwen; Li, Zhu; McDonald, Thomas; Donnelly, K C

    2008-10-01

    Settled house dust can be a source of human exposure to toxic polycyclic aromatic hydrocarbons (PAHs) through non-dietary ingestion and dermal contact. Information regarding the concentrations of various contaminants in house dust would be useful in estimating the risk associated with exposure to these compounds. This study reports on the surface loading, variability and distribution of PAHs in settled house dust collected from homes in three locations: Sumgayit, Azerbaijan; Shanxi Province, China; and southern Texas, United States. The highest PAH floor surface loadings were observed in China, followed by Azerbaijan and Texas. Median concentrations of high molecular weight (four ring and larger) PAHs ranged from a low of 0.11 microg/m(2) in Texas, to 2.9 microg/m(2) in Azerbaijan and 162 microg/m(2) in China. These trends in total surface loading and relative carcinogenicity indicate that the risk of health effects from exposure to PAHs in house dust is highest in the Chinese population and lowest in the Texas population. As anticipated, variability among dust samples from different houses within the same region was high, with coefficients of variation greater than 100%. Alkylated PAHs comprised 30-50% of the total mass of PAHs. Based on a comparison of the composition of specific components, PAHs in China and Azerbaijan were determined to be derived mainly from combustion sources rather than from unburned fossil fuels such as petroleum. These results, coupled with ongoing investigation of appropriate PAH exposure biomarkers in humans, will guide future efforts to identify ways to reduce exposures in the study areas. PMID:18452990

  12. Has Alberta Oil Sands Development Altered Delivery of Polycyclic Aromatic Compounds to the Peace-Athabasca Delta?

    PubMed Central

    Hall, Roland I.; Wolfe, Brent B.; Wiklund, Johan A.; Edwards, Thomas W. D.; Farwell, Andrea J.; Dixon, D. George

    2012-01-01

    Background The extent to which Alberta oil sands mining and upgrading operations have enhanced delivery of bitumen-derived contaminants via the Athabasca River and atmosphere to the Peace-Athabasca Delta (200 km to the north) is a pivotal question that has generated national and international concern. Accounts of rare health disorders in residents of Fort Chipewyan and deformed fish in downstream ecosystems provided impetus for several recent expert-panel assessments regarding the societal and environmental consequences of this multi-billion-dollar industry. Deciphering relative contributions of natural versus industrial processes on downstream supply of polycyclic aromatic compounds (PACs) has been identified as a critical knowledge gap. But, this remains a formidable scientific challenge because loading from natural processes remains unknown. And, industrial activity occurs in the same locations as the natural bitumen deposits, which potentially confounds contemporary upstream-downstream comparisons of contaminant levels. Methods/Principal Findings Based on analyses of lake sediment cores, we provide evidence that the Athabasca Delta has been a natural repository of PACs carried by the Athabasca River for at least the past two centuries. We detect no measureable increase in the concentration and proportion of river-transported bitumen-associated indicator PACs in sediments deposited in a flood-prone lake since onset of oil sands development. Results also reveal no evidence that industrial activity has contributed measurably to sedimentary concentration of PACs supplied by atmospheric transport. Conclusions/Significance Findings suggest that natural erosion of exposed bitumen in banks of the Athabasca River and its tributaries is a major process delivering PACs to the Athabasca Delta, and the spring freshet is a key period for contaminant mobilization and transport. This baseline environmental information is essential for informed management of natural resources

  13. Analysis of Plant Growth-Promoting Effects of Fluorescent Pseudomonas Strains Isolated from Mentha piperita Rhizosphere and Effects of Their Volatile Organic Compounds on Essential Oil Composition.

    PubMed

    Santoro, Maricel V; Bogino, Pablo C; Nocelli, Natalia; Cappellari, Lorena Del Rosario; Giordano, Walter F; Banchio, Erika

    2016-01-01

    Many species or strains of the genus Pseudomonas have been characterized as plant growth promoting rhizobacteria (PGPR). We used a combination of phenotypic and genotypic techniques to analyze the community of fluorescent Pseudomonas strains in the rhizosphere of commercially grown Mentha piperita (peppermint). Biochemical techniques, Amplified rDNA Restriction Analysis (ARDRA), and 16S rRNA gene sequence analysis revealed that the majority of the isolated native fluorescent strains were P. putida. Use of two Repetitive Sequence-based PCR (rep-PCR) techniques, BOX-PCR and ERIC-PCR, allowed us to evaluate diversity among the native strains and to more effectively distinguish among them. PGPR activity was tested for the native strains and reference strain P. fluorescens WCS417r. Micropropagated M. piperita plantlets were exposed to microbial volatile organic compounds (mVOCs) emitted by the bacterial strains, and plant biomass parameters and production of essential oils (EOs) were measured. mVOCs from 11 of the native strains caused an increase in shoot fresh weight. mVOCs from three native strains (SJ04, SJ25, SJ48) induced changes in M. pierita EO composition. The mVOCs caused a reduction of metabolites in the monoterpene pathway, for example menthofuran, and an increase in menthol production. Menthol production is the primary indicator of EO quality. The mVOCs produced by native strains SJ04, SJ25, SJ48, and strain WCS417r were analyzed. The obtained mVOC chromatographic profiles were unique for each of the three native strains analyzed, containing varying hydrocarbon, aromatic, and alogenic compounds. The differential effects of the strains were most likely due to the specific mixtures of mVOCs emitted by each strain, suggesting a synergistic effect occurs among the compounds present. PMID:27486441

  14. Analysis of Plant Growth-Promoting Effects of Fluorescent Pseudomonas Strains Isolated from Mentha piperita Rhizosphere and Effects of Their Volatile Organic Compounds on Essential Oil Composition

    PubMed Central

    Santoro, Maricel V.; Bogino, Pablo C.; Nocelli, Natalia; Cappellari, Lorena del Rosario; Giordano, Walter F.; Banchio, Erika

    2016-01-01

    Many species or strains of the genus Pseudomonas have been characterized as plant growth promoting rhizobacteria (PGPR). We used a combination of phenotypic and genotypic techniques to analyze the community of fluorescent Pseudomonas strains in the rhizosphere of commercially grown Mentha piperita (peppermint). Biochemical techniques, Amplified rDNA Restriction Analysis (ARDRA), and 16S rRNA gene sequence analysis revealed that the majority of the isolated native fluorescent strains were P. putida. Use of two Repetitive Sequence-based PCR (rep-PCR) techniques, BOX-PCR and ERIC-PCR, allowed us to evaluate diversity among the native strains and to more effectively distinguish among them. PGPR activity was tested for the native strains and reference strain P. fluorescens WCS417r. Micropropagated M. piperita plantlets were exposed to microbial volatile organic compounds (mVOCs) emitted by the bacterial strains, and plant biomass parameters and production of essential oils (EOs) were measured. mVOCs from 11 of the native strains caused an increase in shoot fresh weight. mVOCs from three native strains (SJ04, SJ25, SJ48) induced changes in M. pierita EO composition. The mVOCs caused a reduction of metabolites in the monoterpene pathway, for example menthofuran, and an increase in menthol production. Menthol production is the primary indicator of EO quality. The mVOCs produced by native strains SJ04, SJ25, SJ48, and strain WCS417r were analyzed. The obtained mVOC chromatographic profiles were unique for each of the three native strains analyzed, containing varying hydrocarbon, aromatic, and alogenic compounds. The differential effects of the strains were most likely due to the specific mixtures of mVOCs emitted by each strain, suggesting a synergistic effect occurs among the compounds present. PMID:27486441

  15. Identification of Fluorescent Compounds with Non-Specific Binding Property via High Throughput Live Cell Microscopy

    PubMed Central

    Nath, Sangeeta; Spencer, Virginia A.; Han, Ju; Chang, Hang; Zhang, Kai; Fontenay, Gerald V.; Anderson, Charles; Hyman, Joel M.; Nilsen-Hamilton, Marit; Chang, Young-Tae; Parvin, Bahram

    2012-01-01

    Introduction Compounds exhibiting low non-specific intracellular binding or non-stickiness are concomitant with rapid clearing and in high demand for live-cell imaging assays because they allow for intracellular receptor localization with a high signal/noise ratio. The non-stickiness property is particularly important for imaging intracellular receptors due to the equilibria involved. Method Three mammalian cell lines with diverse genetic backgrounds were used to screen a combinatorial fluorescence library via high throughput live cell microscopy for potential ligands with high in- and out-flux properties. The binding properties of ligands identified from the first screen were subsequently validated on plant root hair. A correlative analysis was then performed between each ligand and its corresponding physiochemical and structural properties. Results The non-stickiness property of each ligand was quantified as a function of the temporal uptake and retention on a cell-by-cell basis. Our data shows that (i) mammalian systems can serve as a pre-screening tool for complex plant species that are not amenable to high-throughput imaging; (ii) retention and spatial localization of chemical compounds vary within and between each cell line; and (iii) the structural similarities of compounds can infer their non-specific binding properties. Conclusion We have validated a protocol for identifying chemical compounds with non-specific binding properties that is testable across diverse species. Further analysis reveals an overlap between the non-stickiness property and the structural similarity of compounds. The net result is a more robust screening assay for identifying desirable ligands that can be used to monitor intracellular localization. Several new applications of the screening protocol and results are also presented. PMID:22242152

  16. Isolation of an extremely halophilic arhaeon Natrialba sp. C21 able to degrade aromatic compounds and to produce stable biosurfactant at high salinity.

    PubMed

    Khemili-Talbi, Souad; Kebbouche-Gana, Salima; Akmoussi-Toumi, Siham; Angar, Yassmina; Gana, Mohamed Lamine

    2015-11-01

    Natrialba sp. strain C21 was isolated from oil contaminated saline water in Ain Salah (Algeria) and has exhibited a good potential for degrading phenol (3% v/v), naphthalene (3% v/v), and pyrene (3% v/v) at high salinity with high growth, enzymatic activity and biosurfactant production. Successful metabolism of aromatic hydrocarbon compounds of the strain Natrialba sp. C21 appears to require the ortho-cleavage pathway. Indeed, assays of the key enzymes involved in the ring cleavage of catechol 1, 2-dioxygenase indicated that degradation of the phenol, naphthalene and pyrene by strain Natrialba sp. C21 was via the ortho-cleavage pathway. Cells grown on aromatic hydrocarbons displayed greater ortho-activities mainly towards catechol, while the meta-activity was very low. Besides, biosurfactants derived from the strain C21 were capable of effectively emulsifying both aromatic and aliphatic hydrocarbons and seem to be particularly promising since they have particular adaptations like the increased stability at high temperature and salinity conditions. This study clearly demonstrates for the first time that strain belonging to the genera Natrialba is able to grow at 25% (w/v) NaCl, utilizing phenol, naphthalene, and pyrene as the sole carbon sources. The results suggest that the isolated halophilic archaeon could be a good candidate for the remediation process in extreme environments polluted by aromatic hydrocarbons. Moreover, the produced biosurfactant offers a multitude of interesting potential applications in various fields of biotechnology. PMID:26334644

  17. Characterization of trace organic compounds associated with aged and diluted sidestream tobacco smoke in a controlled atmosphere—volatile organic compounds and polycyclic aromatic hydrocarbons

    NASA Astrophysics Data System (ADS)

    Baek, Sung-Ok; Jenkins, Roger A.

    In this study, a wide range of volatile organic constituents of aged and diluted sidestream tobacco smoke (ADSS) were determined in a controlled atmosphere, where ADSS is the sole source of target compounds. The ADSS was generated in a 30 m 3 environmental test chamber using a variety of cigarettes, including the Kentucky 1R4F reference cigarette and eight commercial brands, and a total of 24 experimental runs were conducted. Target analytes were divided into three groups, i.e. vapor and particulate phase markers for environmental tobacco smoke (ETS), volatile organic compounds (VOC) including carbonyls, and polycyclic aromatic hydrocarbons (PAH). The VOC samples were collected on triple sorbent traps, and then analyzed by thermal desorption coupled with gas chromatography/mass spectrometry (GC/MS), while the carbonyl compounds were sampled on DNPH cartridges, being analyzed by HPLC. ETS particles in the chamber were collected by high volume sampling, and then used for the determination of PAHs by GC/MS. Among more than 30 target VOCs, acetaldehyde appeared to be the most abundant compound, followed by 2-methyl-1,3-butadiene, and formaldehyde. The results from the chamber study were further used to generate characterized ratios of selected VOCs to 3-ethenyl pyridine (3-EP), a vapor phase ETS marker. The ratios appeared to be in generally good agreement with published values in the literature. This suggests that the characteristic ratios may be useful for quantifying the impact of ETS on the VOC concentrations in 'real world' indoor environments, which are affected by a complex mixture of components from multiple sources. The yields of ETS markers from this study are all slightly lower than those estimated by other studies, while VOC yields are in reasonable agreement in many cases with values in the literature. Among 16 target PAHs, chrysene appeared to be most abundant, followed by benzo(a)anthracene (BaA) and benzo(a)pyrene (BaP). The average contents of BaP and

  18. Syntheses of fluorescent thiocyanate supramolecular compounds with unusual two-dimensional structures

    SciTech Connect

    Bie Haiying; Lu Jing; Yu Jiehui; Xu Jiqing . E-mail: xjq@mail.jlu.edu.cn; Zhao Kui; Zhang Xiao

    2005-05-15

    Three novel thiocyanate supramolecular compounds have been synthesized and characterized by X-ray diffraction and fluorescent spectra. Compound [pipH]{sub 2}[Co(NCS){sub 4}] (pip=piperazine) 1 possesses a two-dimensional layer connected by the combination of N-H...N hydrogen bonds and weak S...S contacts. Under the same conditions, using nickel salt instead of cobalt salt as a starting material, we obtained a different two-dimensional supramolecular layer [pipH]{sub 2}[Ni(NCS){sub 4}] 2 connected by unusual N-H...S hydrogen bonds and weak S...S contacts. In order to observe the influence of the dimension of ligand on the self-assembly structure, dabco was used for substituting pip, and compound [dabcoH]{sub 2}[Ni(NCS){sub 4}] (dabco=1,4-Diazabicyclo[2.2.2] octane) 3 was gained, which constructed two-dimensional, highly wavy network with hourglass-shaped cavities only through N-H...S hydrogen bonds.

  19. Syntheses of fluorescent thiocyanate supramolecular compounds with unusual two-dimensional structures

    NASA Astrophysics Data System (ADS)

    Bie, Hai-Ying; Lu, Jing; Yu, Jie-Hui; Xu, Ji-Qing; Zhao, Kui; Zhang, Xiao

    2005-05-01

    Three novel thiocyanate supramolecular compounds have been synthesized and characterized by X-ray diffraction and fluorescent spectra. Compound [pipH] 2[Co(NCS) 4] (pip=piperazine) 1 possesses a two-dimensional layer connected by the combination of N-H⋯N hydrogen bonds and weak S⋯S contacts. Under the same conditions, using nickel salt instead of cobalt salt as a starting material, we obtained a different two-dimensional supramolecular layer [pipH] 2[Ni(NCS) 4] 2 connected by unusual N-H⋯S hydrogen bonds and weak S⋯S contacts. In order to observe the influence of the dimension of ligand on the self-assembly structure, dabco was used for substituting pip, and compound [dabcoH] 2[Ni(NCS) 4] (dabco=1,4-Diazabicyclo[2.2.2] octane) 3 was gained, which constructed two-dimensional, highly wavy network with hourglass-shaped cavities only through N-H⋯S hydrogen bonds.

  20. Ab initio and sup 17 O NMR study of aromatic compounds with dicoordinate oxygen atoms. (1) Methoxy- and (methylenedioxy)benzene derivatives

    SciTech Connect

    Biekofsky, R.R.; Pomilio, A.B.; Contreras, R.H. ); Orendt, A.M.; Facelli, J.C. )

    1990-09-20

    {sup 17}O NMR data at natural abundance in toluene-d{sub 8} at 74{degree}C were obtained for aromatic compounds containing methoxy and methylenedioxy groups as side-chains substituents. {sup 17}O chemical shifts of this series of compounds are significantly influenced by both electronic and steric effects. Ortho electronic and steric substituent chemical shift effects for methoxy and methylenedioxy groups were estimated. Ab initio calculations at the 4-31G level were used to determine geometries of the compounds to gain insight into the structural aspects of these compounds. A correlation between the calculated bond orders, P{sub C{sub Ar}P{minus}O}, and the {sup 17}O chemical shift was found.

  1. Investigation of two-photon absorption properties in new A-D-A compounds emitting blue and yellow fluorescence

    NASA Astrophysics Data System (ADS)

    Jin, Fan; Cai, Zhi-Bin; Huang, Jiu-Qiang; Li, Sheng-Li; Tian, Yu-Peng

    2015-08-01

    Three new acceptor-donor-acceptor compounds (LBQ, DBQ, BYQ) were synthesized and characterized by infrared, hydrogen nuclear magnetic resonance, mass spectrometry and elemental analysis. Their photophysical properties were investigated including linear absorption, single-photon excited fluorescence, fluorescence quantum yield and two-photon absorption. These compounds in CH2Cl2 exhibit good fluorescence quantum yield which are 0.36, 0.26, and 0.25 and the largest two-photon absorption cross-section which are 48, 36, and 181 GM respectively. Under the excitation of Ti: sapphire laser with a pulse width of 140 fs, LBQ and DBQ emit blue two-photon excited fluorescence (TPEF), while BYQ emits bright yellow TPEF. BYQ has a good solubility in water and the σ can be as large as 130 GM, so it shows promising applications in many pharmaceutical and biological fields.

  2. On-line and in-situ detection of polycyclic aromatic hydrocarbons (PAH) on aerosols via thermodesorption and laser-induced fluorescence spectroscopy.

    PubMed

    Panne, U; Knöller, A; Kotzick, R; Niessner, R

    2000-02-01

    A fiber optical sensor system for the determination of polycyclic aromatic hydrocarbons (PAH) on aerosols by laser-induced, time-resolved fluorescence is combined with a thermodesorption device. The sensor system is based on an aerosol flow cell, which is fibre-optically coupled to a pulsed nitrogen laser for excitation and the detection system. Time-resolved fluorescence emission spectra are detected by a monochromator equipped with a photomultiplier and a fast digital storage oscilloscope. The analytical figures of merit of the thermodenuder are reported for benzo[a]pyrene, benzo[b]fluoranthene, and benzo[ghi]-perylene on ultrafine soot and NaCl aerosols. By thermodesorption of the PAH, problems due to quenching of the PAH fluorescence by the bulk aerosol material or excimer formation on the aerosol surface were avoided. For the PAH under study, the sensitivity was improved considerably and detection limits between 110 and 850 ng m(-3) were attained, while a response time of 2-3 min was achieved with the thermodenuder. A calibration for PAH on ultrafine soot and NaCl aerosols was established independent of the aerosol substrate. PMID:11220329

  3. Application of a quantitative structure retention relationship approach for the prediction of the two-dimensional gas chromatography retention times of polycyclic aromatic sulfur heterocycle compounds.

    PubMed

    Gieleciak, Rafal; Hager, Darcy; Heshka, Nicole E

    2016-03-11

    Information on the sulfur classes present in petroleum is a key factor in determining the value of refined products and processing behavior in the refinery. A large part of the sulfur present is included in polycyclic aromatic sulfur heterocycles (PASHs), which in turn are difficult to desulfurize. Furthermore, some PASHs are potentially more mutagenic and carcinogenic than polycyclic aromatic hydrocarbons, PAHs. All of this calls for improved methods for the identification and quantification of individual sulfur species. Recent advances in analytical techniques such as comprehensive two-dimensional gas chromatography (GC×GC) have enabled the identification of many individual sulfur species. However, full identification of individual components, particularly in virgin oil fractions, is still out of reach as standards for numerous compounds are unavailable. In this work, a method for accurately predicting retention times in GC×GC using a QSRR (quantitative structure retention relationship) method was very helpful for the identification of individual sulfur compounds. Retention times for 89 saturated, aromatic, and polyaromatic sulfur-containing heterocyclic compounds were determined using two-dimensional gas chromatography. These retention data were correlated with molecular descriptors generated with CODESSA software. Two independent QSRR relationships were derived for the primary as well as the secondary retention characteristics. The predictive ability of the relationships was tested by using both independent sets of compounds and a cross-validation technique. When the corresponding chemical standards are unavailable, the equations developed for predicting retention times can be used to identify unknown chromatographic peaks by matching their retention times with those of sulfur compounds of known molecular structure. PMID:26879453

  4. Thermally activated delayed fluorescence with circularly polarized luminescence characteristics.

    PubMed

    Imagawa, Takuro; Hirata, Shuzo; Totani, Kenro; Watanabe, Toshiyuki; Vacha, Martin

    2015-09-01

    A metal-free aromatic compound with a chiral carbon sandwiched between a donor moiety and an acceptor moiety was designed. Under thermally activated delayed fluorescence, the compound displayed a photoluminescence quantum yield of 26%, and showed circularly polarized luminescence with a dissymmetry factor of 10(-3). PMID:26207648

  5. Polymer optical fiber compound parabolic concentrator tip for enhanced coupling efficiency for fluorescence based glucose sensors

    PubMed Central

    Hassan, Hafeez Ul; Nielsen, Kristian; Aasmul, Soren; Bang, Ole

    2015-01-01

    We demonstrate that the light excitation and capturing efficiency of fluorescence based fiber-optical sensors can be significantly increased by using a CPC (Compound Parabolic Concentrator) tip instead of the standard plane-cut tip. We use Zemax modelling to find the optimum CPC tip profile and fiber length of a polymer optical fiber diabetes sensor for continuous monitoring of glucose levels. We experimentally verify the improved performance of the CPC tipped sensor and the predicted production tolerances. Due to physical size requirements when the sensor has to be inserted into the body a non-optimal fiber length of 35 mm is chosen. For this length an average improvement in efficiency of a factor of 1.7 is experimentally demonstrated and critically compared to the predicted ideal factor of 3 in terms of parameters that should be improved through production optimization. PMID:26713213

  6. Standoff detection and classification procedure for bioorganic compounds by hyperspectral laser-induced fluorescence

    NASA Astrophysics Data System (ADS)

    Fischbach, Thomas; Duschek, Frank; Hausmann, Anita; Pargmann, Carsten; Aleksejev, Valeri; Poryvkina, Larisa; Sobolev, Innokenti; Babichenko, Sergey; Handke, Jürgen

    2015-05-01

    The high and still increasing number of attacks by hazardous bioorganic materials makes enormous demands on their detection. A very high detection sensitivity and differentiability are essential, as well as a rapid identification with low false alarm rates. One single technology can hardly achieve this. Point sensors can collect and identify materials, but finding an appropriate position is time consuming and involves several risks. Laser based standoff detection, however, can immediately provide information on propagation and compound type of a released hazardous material. The coupling of both methods may illustrate a solution to optimize the acquisition and detection of hazardous substances. At DLR Lampoldshausen, bioorganic substances are measured, based on laser induced fluorescence (LIF), and subsequently classified. In this work, a procedure is presented, which utilizes lots of information (time-dependent spectral data, local information) and predicts the presence of hazardous substances by statistical data analysis. For that purpose, studies are carried out on a free transmission range at a distance of 22m at two different excitation wavelengths alternating between 280nm and 355 nm. Time-dependent fluorescence spectra are recorded by a gated intensified CCD camera (iCCD). An automated signal processing allows fast and deterministic data collection and a direct subsequent classification of the detected substances. The variation of the substance parameters (physical state, concentration) is included within this method.

  7. Turn-on fluorescence and unprecedented encapsulation of large aromatic molecules within a manganese(II)-triazole metal-organic confined space.

    PubMed

    Wang, Ying; Yuan, Bin; Xu, Yao-Yao; Wang, Xiu-Guang; Ding, Bin; Zhao, Xiao-Jun

    2015-01-26

    For the purpose of investigating the coordination behavior of sterically congested alkenes and exploring the possibility of cofacial complexation in the polycyclic aromatic system for the formation of extended polymeric networks, a new tetradentate ligand, 1,1,2,2-tetrakis[4-(1H-1,2,4-triazol-1-yl)phenyl]ethylene (TTPE), has been designed and synthesized. By using TTPE as a building block with regard to the self-assembly with MnCl2 ⋅4 H2 O, a novel two-dimensional coordination framework {[Mn(TTPE)Cl2 ]⋅4 CHCl3 }n (1) can be isolated. Anion-exchange and organic-group-functionalized aromatic guest TTPE-loaded host-guest complex experimental results indicate that coordinated Cl(-) anions in the 2D framework of 1 can be completely replaced with dissociative ClO4 (-) groups in an irreversible single-crystal-to-single-crystal transformation fashion, as evidenced by the anion-exchange products of {[Mn(TTPE)(H2 O)2 ](ClO4 )2 ⋅0.5 TTPE⋅5.25 H2 O}n (2). Interestingly, TTPE, acting as an organic template, was encapsulated in the confined space of the 2D grid of 2. To the best of our knowledge, such large organic molecules encapsulated in the reactive organic-group-functionalized aromatic-guest-loaded host-guest complex are unprecedented up to now. Luminescence measurements illustrate that 1 and 2 represent novel examples of sensing materials based on triazole derivatives. Further, 2 has been demonstrated by tuning the fluorescence response of porous metal-organic frameworks as a function of adsorbed small analytes. PMID:25449539

  8. Measurement of aromatic compounds in automobile exhaust gases with membrane inlet mass spectrometry equipped with an on-line-probe and an automatic Tenax-Sampler

    SciTech Connect

    Matz, G.; Walte, A.; Muenchmeyer, W.; Rikeit, H.E.

    1996-09-01

    A novel membrane inlet mass spectrometer is used to monitor organic compounds in combustion emissions. Different gas probes, which can be changed in minutes, have been developed for use in combination with the mobile mass spectrometer. With the On-Line-Probe, volatile organic compounds (BTXE) can be measured down to the ppm range with a cycle rate of one analysis per second. Time resolved measurements of aromatic compounds together with other exhaust gases can be done. By sampling with a polymer adsorbent, analysis with thermal desorption and GC/MS down to the ppb concentration range can be achieved. A six-fold Tenax-Sampler, connected to the mobile GC/MS system, is capable of taking and transferring the samples automatically. Because sampling with this device is independent from the analysis, measurements of narrow time windows in a dynamical process can be done easily. The whole analytical equipment was evaluated on-site through measurements on an engine test stand, a dynamometer and on the road during real traffic. It is shown, that time resolved quantitative measurements give information on the influence of special driving conditions (warm up, congestion) on the amount of aromatic compounds emitted by automobile exhausts.

  9. Simultaneous metabolism of chloro- and methyl-aromatic compounds by selected bacterial strains. Final report, 20 August 1991-19 August 1992

    SciTech Connect

    Focht, D.D.

    1993-05-27

    Microorganisms are frequently able to degrade anthropogenic materials using pathways that evolved for the assimilation of related naturally-occurring compounds. Complications can arise, however, during the metabolism of mixtures when incompatible intermediates are formed from different components. The breakdown of chloro- and methyl-aromatics, for example, produces catechols which are oxidized differently: chlorocatechols are normally cleaved by ortho fission and methylcatechols by meta fission. If both systems act simultaneously, suicide substrates or dead-end metabolites are usually formed. Nevertheless, bacteria differ in their, ability to cope with such mixtures. A unique bacterium, Pseudomonas cepacia MB2 was isolated by selective enrichment on 2-methylbenzoate, yet was also able to fortuitously utilize 3-chloro-2-methylbenzoate as a sole carbon source. This strain is unique in its ability to utilize an aromatic acid containing both a methyl and chloro substituent via the metafission pathway without the production of suicidal products.

  10. Acute toxicity and synergistic and antagonistic effects of the aromatic compounds of some essential oils against Culex quinquefasciatus Say larvae.

    PubMed

    Pavela, Roman

    2015-10-01

    The efficacy of 30 aromatic compounds and their mutual binary combinations was assessed for acute toxicity against the larvae Culex quinquefasciatus. Based on comparison of the lethal doses, thymol and p-cymene were selected as the most effective (LD50 = 18 and 21 mg L(-1), respectively, and LD90 = 25 and 30 mg L(-1), respectively). Although the LD50 for terpinolene and trans-anethole was also estimated at 21 mg L(-1), their LD90 was significantly higher compared to the substances above (245 and 34 mg L(-1), respectively). In total, 435 binary combinations were tested, of which 249 combinations showed a significant synergistic effect, while 74 combinations showed a significant antagonistic effect on mortality. Only nine substances were identified as being able to create a synergistic effect with more than 20 substances: limonene, trans-anethole, 4-allylanisole, carvacrol, isoeugenol, menthone, carvone, borneol, and camphor. The highest synergistic effect on larval mortality was achieved for the combinations: eugenol and isoeugenol, carvone and carvacrol, carvone and 4-allylanisole, carvone and α-terpineol, carvone and menthone, limonene and trans-anethole, limonene and menthone, α-pinene and menthone, β-citronellol and menthone, carvacrol and 4-allylanisole, carvacrol and terpineol, α-terpinene and trans-anethole, camphor and menthone, camphene and menthone, and 4-allylanisole and menthone. Significant differences between achieved mortality and the mutual mixing ratio were found for the five selected binary mixtures that had shown the most significant synergistic effect in the previous tests. The mixture of limonene and trans-anethole showed the highest mortality, with the mixing ratio 1:1; the mixture of eugenol and isoeugenol caused 90.2% mortality, with the mixing ratio 1:3. One hundred percent mortality was achieved if carvacrol was contained in a mixture with carvone in a ratio >2. After a comparison of all our results, based on our experiments, we

  11. Infrared Spectroscopy of Matrix-Isolated Polycyclic Aromatic Compounds and Their Ions. 7; Phenazine, a Dual Substituted Polycyclic Aromatic Nitrogen Heterocycle

    NASA Technical Reports Server (NTRS)

    Mattioda, A. L.; Hudgins, D. M.; Bauschlicher, C. W., Jr.; Allamandola, L. J.

    2004-01-01

    The matrix-isolation technique has been employed to measure the mid-infrared spectra of phenazine (C12H8N2), a dual substituted Polycyclic Aromatic Nitrogen Heterocycle (PANH), in the neutral, cationic and anionic forms. The experimentally measured band frequencies and intensities are tabulated and compared with their calculated values as well as those of the non-substituted parent molecule, anthracene. The theoretical band positions and intensities were calculated using both the 3-31 G as well as the larger 6-3lG* Basis Sets. A comparison of the results can be found in the tables. The spectroscopic properties of phenazine and its cation are similar to those observed in mono-substituted PANHs, with one exception. The presence of a second nitrogen atom results in an additional enhancement of the cation's total integrated intensity, for the 1500-1000 cm(sup -1) (6.7 to 10 micron) region, over that observed for a mono-substituted PANH cation. The significance of this enhancement and the astrobiological implications of these results are discussed.

  12. Pyrolysis of simple coal model compounds containing aromatic carboxylic acids: Does decarboxylation lead to cross-linking?

    SciTech Connect

    Eskay, T.P.; Britt, P.F.; Buchanan, A.C.

    1996-10-01

    Recently, a number of studies have shown that the evolution of CO{sub 2} from carboxylate groups is a key indicator of cross-linking reactions in pyrolysis and liquefaction of low rank coals. This result suggests that the thermal decarboxylation may occur by a pathway which initiates retrogressive reactions in the coal polymer. However, the chemistry of the thermal decomposition of aromatic carboxylic acids is not thoroughly understood. To provide insight into the thermal decarboxylation of aromatic carboxylic acids, and the role decarboxylation may play in coal pyrolysis, we have conducted a study of the pyrolysis of several bibenzyls containing aromatic carboxylic acids. The results of our pyrolysis study and the relevance of thermal decarboxylation on coal cross-linking reactions will be discussed.

  13. Application of p-toluidine in chromogenic detection of catechol and protocatechuate, diphenolic intermediates in catabolism of aromatic compounds

    SciTech Connect

    Parke, D. )

    1992-08-01

    In the presence of p-toluidine and iron, protocatechuate and catechols yield color. Inclusion of p-toluidine in media facilities the screening of microbial strains for alterations affecting aromatic catabolism. Such strains include mutants affected in the expression of oxygenases and Escherichia coli colonies carrying cloned or subcloned aromatic catabolic genes which encode enzymes giving rise to protocatechuate or catechol. The diphenolic detection system can also be applied to the creation of vectors relying on insertion of cloned DNA into one of the latter marker genes.

  14. USE OF FLUORESCENT POLYCYLIC AROMATIC HYDROCARBON PROBES IN STUDYING THE IMPACT OF COLLOIDS ON POLLUTANT TRANSPORT IN GROUNDWATER

    EPA Science Inventory

    A fluorescence-quenching method was developed to assess the hydrophobic organic pollutant binding potential of organic colloids (OC) in unaltered natural waters. This method allows (1) direct assessment of the importance of OC-enhanced pollutant transport for environmental sam- p...

  15. Native fluorescence detection of biomolecular and pharmaceutical compounds in capillary electrophoresis: detector designs, performance and applications: a review.

    PubMed

    de Kort, Bregje J; de Jong, Gerhardus J; Somsen, Govert W

    2013-03-01

    This review treats the coupling of capillary electrophoresis (CE) with fluorescence detection (Flu) for the analysis of natively fluorescent biomolecular and pharmaceutical compounds. CE-Flu combines the excellent separation efficiency of CE with the high selectivity and sensitivity of Flu. In CE-Flu, an appropriate design of the fluorescence detection cell is very important in order to achieve efficient analyte excitation in and emission light collection from the small cylindrically-shaped detection volume. Therefore, due attention is paid to the various optical detection designs used for CE-Flu, including the applied excitation sources and emission light detectors. Special attention is devoted to wavelength-resolved Flu and to sensitivity issues. Furthermore, he specific requirements for fluorescence detection in microfluidic systems (i.e. chip-based electrophoresis) are discussed. Subsequently, an overview of described applications of CE-Flu for the analysis of natively fluorescent biomolecules and drugs is presented in extensive tables, treating amino acids, peptides, proteins, bioactive compounds, flavins, pharmaceuticals and also single cell analysis. The tables provide information on analyte nature, sample matrix, optical detection aspects, CE mode and limits of detection. A selection of descriptive applications is discussed in detail to illustrate the potential of native fluorescence detection in CE. It is concluded that CE-Flu is a powerful tool for biomolecular and pharmaceutical analysis, and provides good opportunities for use in lab-on-chip devices. PMID:23427797

  16. Diterpenoids and aromatic compounds from the three New Zealand liverworts Jamesoniella kirkii, Balantiopsis rosea, and Radula species.

    PubMed

    Nagashima, Fumihiro; Kuba, Yoshiyuki; Asakawa, Yoshinori

    2006-06-01

    Three new aromatics were isolated from the New Zealand liverwort Balantiopsis rosea. A new bibenzyl was isolated from an unidentified Radula species, together with known bibenzyls. Jamesoniella kirkii yielded three known ent-isopimarane and two ent-kaurane diterpenoids. Their structures were confirmed by NMR techniques, chemical reaction, and X-ray crystallographic analysis. PMID:16755068

  17. Graphene stabilized ultra-small CuNi nanocomposite with high activity and recyclability toward catalysing the reduction of aromatic nitro-compounds

    NASA Astrophysics Data System (ADS)

    Fang, Hao; Wen, Ming; Chen, Hanxing; Wu, Qingsheng; Li, Weiying

    2015-12-01

    Nowadays, it is of great significance and a challenge to design a noble-metal-free catalyst with high activity and a long lifetime for the reduction of aromatic nitro-compounds. Here, a 2D structured nanocomposite catalyst with graphene supported CuNi alloy nanoparticles (NPs) is prepared, and is promising for meeting the requirements of green chemistry. In this graphene/CuNi nanocomposite, the ultra-small CuNi nanoparticles (~2 nm) are evenly anchored on graphene sheets, which is not only a breakthrough in the structures, but also brings about an outstanding performance in activity and stability. Combined with a precise optimization of the alloy ratios, the reaction rate constant of graphene/Cu61Ni39 reached a high level of 0.13685 s-1, with a desirable selectivity as high as 99% for various aromatic nitro-compounds. What's more, the catalyst exhibited a unprecedented long lifetime because it could be recycled over 25 times without obvious performance decay or even a morphology change. This work showed the promise and great potential of noble-metal-free catalysts in green chemistry.Nowadays, it is of great significance and a challenge to design a noble-metal-free catalyst with high activity and a long lifetime for the reduction of aromatic nitro-compounds. Here, a 2D structured nanocomposite catalyst with graphene supported CuNi alloy nanoparticles (NPs) is prepared, and is promising for meeting the requirements of green chemistry. In this graphene/CuNi nanocomposite, the ultra-small CuNi nanoparticles (~2 nm) are evenly anchored on graphene sheets, which is not only a breakthrough in the structures, but also brings about an outstanding performance in activity and stability. Combined with a precise optimization of the alloy ratios, the reaction rate constant of graphene/Cu61Ni39 reached a high level of 0.13685 s-1, with a desirable selectivity as high as 99% for various aromatic nitro-compounds. What's more, the catalyst exhibited a unprecedented long lifetime

  18. Far infrared (terahertz) spectroscopy of a series of polycyclic aromatic hydrocarbons and application to structure interpretation of asphaltenes and related compounds

    NASA Astrophysics Data System (ADS)

    Cataldo, Franco; Angelini, Giancarlo; García-Hernández, D. A.; Manchado, Arturo

    2013-07-01

    A series of 33 different polycyclic aromatic hydrocarbons (PAHs) were studied by far infrared spectroscopy (terahertz spectroscopy) in the spectral range comprised between 600 and 50 cm-1. In addition to common PAHs like naphthalene, anthracene, phenanthrene, fluoranthene, picene, pyrene, benzo[α]pyrene, and perylene, also quite unusual PAHs were studied like tetracene, pentacene, acenaphtene, acenaphtylene, triphenylene, and decacyclene. A series of alkylated naphthalenes and anthracenes were studied as well as methypyrene. Partially or totally hydrogenated PAHs were also object of the present investigation, ranging from tetrahydronaphthalene (tetralin) to decahydronaphthalene (decalin), 9,10-dihydroanthracene, 9,10-dihydrophenanthrene, hexahydropyrene, and dodecahydrotriphenylene. Finally, the large and quite rare PAHs coronene, quaterrylene, hexabenzocoronene, and dicoronylene were studied by far infrared spectroscopy. The resulting reference spectra were used in the interpretation of the chemical structure of asphaltenes (as extracted from a heavy petroleum fraction and from bitumen), the chemical structures of other petroleum fractions known as DAE (distillate aromatic extract) and RAE (residual aromatic extract), and a possible interpretation of components of the chemical structure of anthracite coal. Asphaltenes, heavy petroleum fractions, and coal were proposed as model compounds for the interpretation of the emission spectra of certain proto-planetary nebulae (PPNe) with a good matching in the mid infrared between the band pattern of the PPNe emission spectra and the spectra of these oil fractions or coal. Although this study was finalized in an astrochemical context, it may find application also in the petroleum and coal chemistry.

  19. Far infrared (terahertz) spectroscopy of a series of polycyclic aromatic hydrocarbons and application to structure interpretation of asphaltenes and related compounds.

    PubMed

    Cataldo, Franco; Angelini, Giancarlo; García-Hernández, D Aníbal; Manchado, Arturo

    2013-07-01

    A series of 33 different polycyclic aromatic hydrocarbons (PAHs) were studied by far infrared spectroscopy (terahertz spectroscopy) in the spectral range comprised between 600 and 50 cm(-1). In addition to common PAHs like naphthalene, anthracene, phenanthrene, fluoranthene, picene, pyrene, benzo[α]pyrene, and perylene, also quite unusual PAHs were studied like tetracene, pentacene, acenaphtene, acenaphtylene, triphenylene, and decacyclene. A series of alkylated naphthalenes and anthracenes were studied as well as methypyrene. Partially or totally hydrogenated PAHs were also object of the present investigation, ranging from tetrahydronaphthalene (tetralin) to decahydronaphthalene (decalin), 9,10-dihydroanthracene, 9,10-dihydrophenanthrene, hexahydropyrene, and dodecahydrotriphenylene. Finally, the large and quite rare PAHs coronene, quaterrylene, hexabenzocoronene, and dicoronylene were studied by far infrared spectroscopy. The resulting reference spectra were used in the interpretation of the chemical structure of asphaltenes (as extracted from a heavy petroleum fraction and from bitumen), the chemical structures of other petroleum fractions known as DAE (distillate aromatic extract) and RAE (residual aromatic extract), and a possible interpretation of components of the chemical structure of anthracite coal. Asphaltenes, heavy petroleum fractions, and coal were proposed as model compounds for the interpretation of the emission spectra of certain proto-planetary nebulae (PPNe) with a good matching in the mid infrared between the band pattern of the PPNe emission spectra and the spectra of these oil fractions or coal. Although this study was finalized in an astrochemical context, it may find application also in the petroleum and coal chemistry. PMID:23603577

  20. Surfactants, Aromatic and Isoprenoid Compounds, and Fatty Acid Biosynthesis Inhibitors Suppress Staphylococcus aureus Production of Toxic Shock Syndrome Toxin 1▿

    PubMed Central

    McNamara, Peter J.; Syverson, Rae Ellen; Milligan-Myhre, Kathy; Frolova, Olga; Schroeder, Sarah; Kidder, Joshua; Hoang, Thanh; Proctor, Richard A.

    2009-01-01

    Menstrual toxic shock syndrome is a rare but potentially life-threatening illness manifest through the actions of Staphylococcus aureus toxic shock syndrome toxin 1 (TSST-1). Previous studies have shown that tampon additives can influence staphylococcal TSST-1 production. We report here on the TSST-1-suppressing activity of 34 compounds that are commonly used additives in the pharmaceutical, food, and perfume industries. Many of the tested chemicals had a minimal impact on the growth of S. aureus and yet were potent inhibitors of TSST-1 production. The TSST-1-reducing compounds included surfactants with an ether, amide, or amine linkage to their fatty acid moiety (e.g., myreth-3-myristate, Laureth-3, disodium lauroamphodiacetate, disodium lauramido monoethanolamido, sodium lauriminodipropionic acid, and triethanolamine laureth sulfate); aromatic compounds (e.g. phenylethyl and benzyl alcohols); and several isoprenoids and related compounds (e.g., terpineol and menthol). The membrane-targeting and -altering effects of the TSST-1-suppressing compounds led us to assess the activity of molecules that are known to inhibit fatty acid biosynthesis (e.g., cerulenin, triclosan, and hexachlorophene). These compounds also reduced S. aureus TSST-1 production. This study suggests that more additives than previously recognized inhibit the production of TSST-1. PMID:19223628

  1. Formation and destruction of the aromatic products of incomplete combustion (PICs) during the chlorinated organic compounds incineration in a lab-scale combustor

    SciTech Connect

    Lin, C.; Li, W.S.; Chen, S.J.; Jeng, R.S.; Chan, C.P.

    1999-07-01

    Thermal destruction is one of the most effective processes to treat organic waste in view of the volume reduction. However, some pollutant emissions associated with waste incineration have led to reluctance to apply this state-of art technology. Proper control of the incineration process with respect to operating parameters to produce flue gases acceptable to the environment is essential for the success of this approach. Better understanding the mechanism of combustion in an incinerator will help the design of more efficient combustion devices. The objective of this research is to investigate the key operating parameters related to the performance of an incinerator using a heterogeneous laboratory scale spouted bed combustor. The spouted bed is considered as an innovative type of fluidized bed and provided with a small centrally located inlet aperture in its conical base which allows a jet of fluid to enter. The ability to use low heat value fuels due to heat recirculation inside the bed and low pollutants emission levels brought down by the long residence time stimulate the application of this combustor in laboratory research. Formation and destruction of the aromatic products of incomplete combustion (PICs) in the post-combustion region for burning toluene and PVC (polyvinyl chloride) is under investigation in this study. The residual hydrocarbons and chlorinated hydrocarbons species are measured. The primary compounds including aromatics, substituted aromatics, and polycyclic aromatics hydrocarbons (PAHs) are formed and destroyed during flue gas passing through the low temperature region. The flue gas samples are induced from the side probes along the reactor with constant flow rate and simultaneously to monitor the temperature by using thermocouples. The sampling train consists of a fiber glass filter and an impinger.

  2. Heterolytic Activation of Hydrogen Promoted by Ruthenium Nanoparticles immobilized on Basic Supports and Hydrogenation of Aromatic Compounds

    NASA Astrophysics Data System (ADS)

    Fang, Minfeng

    Despite the aggressive development and deployment of new renewable and nuclear technologies, petroleum-derived transportation fuels---gasoline, diesel and jet fuels---will continue to dominate the markets for decades. Environmental legislation imposes severe limits on the tolerable proportion of aromatics, sulfur and nitrogen contents in transportation fuels, which is difficult to achieve with current refining technologies. Catalytic hydrogenation plays an important role in the production of cleaner fuels, both as a direct means to reduce the aromatics and as a key step in the hydrodenitrogenation (HDN) and hydrodesulfurization (HDS) processes. However, conventional catalysts require drastic conditions and/or are easily poisoned by S or N aromatics. Therefore, there is still a need for new efficient catalysts for hydrogenation reactions relevant to the production of cleaner fossil fuels. Our catalyst design involves metallic nanoparticles intimately associated with a basic support, with the aim of creating a nanostructure capable of promoting the heterolytic activation of hydrogen and ionic hydrogenation mechanisms, as a strategy to avoid catalyst poisoning and enhance catalytic activity. We have designed and prepared a new nanostructured catalytic material composed of RuNPs immobilized on the basic polymer P4VPy. We have demonstrated that the Ru/P4VPy catalyst can promote heterolytic hydrogen activation and a unique surface ionic hydrogenation mechanism for the efficient hydrogenation of N-aromatics. This is the first time these ionic hydrogenation pathways have been demonstrated on solid surfaces. For the RuNPs surfaces without basic sites in close proximity, the conventional homolytic H2 splitting is otherwise involved. Using the mechanistic concepts from Ru/P4VPy, we have designed and prepared the Ru/MgO catalyst, with the aim to improve the catalytic efficiency for the hydrogenation of heteroatom aromatics operating by the ionic hydrogenation mechanism. The Ru

  3. A high throughput drug screen based on fluorescence resonance energy transfer (FRET) for anticancer activity of compounds from herbal medicine

    PubMed Central

    Tian, H; Ip, L; Luo, H; Chang, D C; Luo, K Q

    2006-01-01

    Background and purpose: We report the development of a very efficient cell-based high throughput screening (HTS) method, which utilizes a novel bio-sensor that selectively detects apoptosis based on the fluorescence resonance energy transfer (FRET) technique. Experimental approach: We generated a stable HeLa cell line expressing a FRET-based bio-sensor protein. When cells undergo apoptosis, they activate a protease called ‘caspase-3'. Activation of this enzyme will cleave our sensor protein and cause its fluorescence emission to shift from a wavelength of 535 nm (green) to 486 nm (blue). A decrease in the green/blue emission ratio thus gives a direct indication of apoptosis. The sensor cells are grown in 96-well plates. After addition of different chemical compounds to each well, a fluorescence profile can be measured at various time-points using a fluorescent plate reader. Compounds that can trigger apoptosis are potential candidates as anti-cancer drugs. Key results: This novel cell-based HTS method is highly effective in identifying anti-cancer compounds. It was very sensitive in detecting apoptosis induced by various known anti-cancer drugs. Further, this system detects apoptosis, but not necrosis, and is thus more useful than the conventional cell viability assays, such as those using MTT. Finally, we used this system to screen compounds, isolated from two plants used in Chinese medicine, and identified several effective compounds for inducing apoptosis. Conclusions and Implications: This FRET-based HTS method is a powerful tool for identifying anti-cancer compounds and can serve as a highly efficient platform for drug discovery. PMID:17179946

  4. Optimization of H3O+/O2+ Dual-mode Ionization in PTR-MS for Simultaneous Detection of Alkanes, Olefins and Aromatic Compounds

    NASA Astrophysics Data System (ADS)

    Amador-Muñoz, O.; Misztal, P. K.; Weber, R.; Drozd, G.; Worton, D. R.; Goldstein, A. H.

    2014-12-01

    Measurements of VOC composition from fossil fuels are analytically challenging because of the complex mixture of hydrocarbons (saturated, unsaturated, aromatics, etc). Speciated chemical measurements typically rely on relatively slow GC separation. Proton transfer reaction mass spectrometry (PTR-MS) is advantageous due to its fast response and high sensitivity. The most common ionization mechanism applied to VOC detection by PTR-MS is proton transfer from hydronium ion (H3O+). However, alkanes cannot be detected using H3O+ ionization chemistry because their proton affinities are too low. Ionization of alkanes is possible via electron transfer and/or hydride abstraction using O2+ or NO+. We used PTR-MS to analyze aromatic, alkene and alkane (linear, branched and cyclic) compounds simultaneously not by switching the ionization agents, but by adjusting the drift tube voltage and optimizing the ratio of H3O+/O2+ produced in the instrument's ion source. The highest detection sensitivity for aromatic and alkene compounds was produced by proton transfer from H3O+, while hydride abstraction by O2+ allowed detection of alkanes. For alkanes, sensitivities ranged from 1.1±0.01 cps/ppbv for n-decane to 74.7±0.25 cps/ppbv for decalin. Sensitivities in O2+ mode were from 6 (Adamantane) to 146 (4-Methyl nonane) times higher than those obtained in H3O+ mode under the same ion source and drift tube voltage conditions. Sensitivities for butyl benzene and 1-decene were 157±0.57 and 66.8±0.21 cps/ppbv, respectively. Sensitivity differences among C10 hydrocarbons are related to their structure, which affects their ionization energies (IE) and hence ease of hydride abstraction. Sensitivities at the parent ion mass were inversely correlated with IE (142 cps/ppbv/eV). This suggests higher electronic stability for cyclic non substituted compounds, followed by cyclic substituted, branch linear and linear C10 hydrocarbons. Although selectivity is a known shortcoming of quadrupole

  5. Technical description of candidate fluorescence compounds and radioisotopes for a nuclear smuggling deterrence tag (IL500E)

    SciTech Connect

    Hartenstein, S.D.; Aryaeinejad, R.

    1996-03-01

    This report summarizes the efforts completed in identifying candidate fluorescence compounds and radioisotopes for a developing tagging system. The tagging system is being developed as a deterrent to nuclear smuggling, by providing a means of: (1) tracing materials and pilferers to the facility of origin for any recovered special nuclear materials; (2) inventory control of long-term stored items containing special nuclear materials; and (3) tracking materials transferred between facilities. The tagging system uses four types of tagging materials to cover a range of applications intended to prevent the pilfering of special nuclear materials. One material, fluorescent compounds which are invisible without ultraviolet or near-infrared detection systems, is marked on controlled items with a tracking pattern that corresponds to a specified item in a specified location in the data control system. The tagging system uses an invisible, fluorescent dusting powder to mark equipment and personnel who inappropriately handle the tagged material. The tagging system also uses unique combinations of radionuclides to identify the facility of origin for any special nuclear material. Currently, 18 long-lived radioisotopes, 38 short-live radioisotopes and 10 fluorescent compounds have been selected as candidate materials for the tagging system.

  6. Photoelectron spectroscopy of aromatic compound clusters of the B12 all-boron benzene: B12Au- and B12(BO)-.

    PubMed

    Bai, Hui; Zhai, Hua-Jin; Li, Si-Dian; Wang, Lai-Sheng

    2013-06-28

    We report a photoelectron spectroscopy and density-functional theory study of the B12Au(-) and B13O(-) clusters and their neutrals, which are shown to be six π electron aromatic compounds between the quasi-planar all-boron B12 benzene-analogue and a monovalent Au or BO ligand. Electron affinities of B12Au and B13O are measured to be 3.48 ± 0.04 and 3.90 ± 0.04 eV, respectively. Structural searches are performed for B12Au(-) and B13O(-), which are compared with the isovalent B12H(-) cluster. The global minima of B12Au(-) and B13O(-) both feature an almost intact B12 cluster with the Au and BO ligands bonded to its periphery, respectively. For B12Au(-), a low-lying isomer is also identified, which is only 0.4 kcal mol(-1) above the global minimum, in agreement with the experimental observation of a weakly populated isomer in the cluster beam of B12Au(-). These aromatic compound clusters provide new examples for the Au/H isolobal analogy and the boronyl (BO) chemistry. PMID:23666408

  7. Investigation of the distribution of organochlorine and polycyclic aromatic hydrocarbon compounds in the Lower Columbia River using semipermeable-membrane devices

    USGS Publications Warehouse

    McCarthy, Kathleen A.; Gale, Robert W.

    1999-01-01

    Organochlorine and polycyclic aromatic hydrocarbon compounds are of concern in the Columbia River Basin because of their adverse effects on fish and wildlife. Because these compounds can have important biological consequences at concentrations well below the detection limits associated with conventional water-sampling techniques, we used semipermeable membrane devices (SPMDs) to sample water, and achieved sub-parts-per-quintillion detection limits. We deployed SPMDs during 1997 low-flow conditions and 1998 high-flow conditions at nine main-stem sites and seven tributary sites, spanning approximately 700 miles of the Columbia River. We also collected streambed sediment from three sites. SPMD extracts and sediments were analyzed for polychlorinated dibenzo-p-dioxins, polychlorinated dibenzofurans, polychlorinated biphenyls, organochlorine pesticides and related transformation products, and polycyclic aromatic hydrocarbons. Our data indicate that (1) in the absence of additional sources, mechanisms such as volatilization, dilution, and settling of suspended particles can act to significantly reduce concentrations of contaminants along the river's flow path, (2) elevated concentrations of contaminants in the Portland-Vancouver area are primarily from local rather than upstream sources, (3) elevated concentrations of many compounds tend to be diluted during periods of high discharge, (4) much higher discharge in the main stem considerably dilutes elevated concentrations entering from tributaries, (5) the distribution of hydrophobic organic compounds in streambed sediment is not necessarily indicative of their distribution in the dissolved-phase, and (6) SPMDs can reveal patterns of contaminant occurrence at environmentally relevant concentrations that are undetectable by conventional water-sampling techniques.

  8. Polybenzimidazole via aromatic nucleophilic displacement

    NASA Technical Reports Server (NTRS)

    Connell, John W. (Inventor); Hergenrother, Paul M. (Inventor); Smith, Joseph G. (Inventor)

    1994-01-01

    Di(hydroxyphenyl)benzimidazole monomers were prepared from phenyl-4-hydroxybenzoate and aromatic bis(o-diamine)s. These monomers were used in the synthesis of soluble polybenzimidazoles. The reaction involved the aromatic nucleophilic displacement of various di(hydroxyphenyl)benzimidazole monomers with activated aromatic dihalides or activated aromatic dinitro compounds in the presence of an alkali metal base. These polymers exhibited lower glass transition temperatures, improved solubility, and better compression moldability over their commercial counterparts.

  9. Development of analytical method for catechol compounds in mouse urine using hydrophilic interaction liquid chromatography with fluorescence detection.

    PubMed

    Kanamori, Takahiro; Isokawa, Muneki; Funatsu, Takashi; Tsunoda, Makoto

    2015-03-15

    An analytical method for catecholamines and related compounds using hydrophilic interaction liquid chromatography (HILIC) with native fluorescence detection has been developed. We found that ZIC-cHILIC with phosphorylcholine was suitable for the separation of catechol compounds with good peak shapes among six different HILIC columns (Inertsil SIL, Inertsil Amide, Inertsil Diol, TSKgel NH2-100, ZIC-HILIC, and ZIC-cHILIC). Using ZIC-cHILIC, eight catechol compounds (dopamine, epinephrine, norepinephrine, 3,4-dihydroxyphenylalanine, 3,4-dihydroxyphenylacetic acid, 3,4-dihydroxyphenylglycol, 3,4-dihydroxymandelic acid, and internal standard 3,4-dihydroxybenzylamine) were separated within 15min. The limit of detection at a signal to noise ratio of 3 was 3-28nM. An improved sensitivity was obtained as compared to that of reversed-phase liquid chromatography. This was partly attributed to the increase in the fluorescence intensity of the catechol compounds in the acetonitrile-rich mobile phase. Solid phase extraction using a monolithic silica disk-packed spin column with phenylboronate moieties, which have affinity to catechol compounds, was performed for the selective extraction of catechol compounds from mouse urine. Dopamine, epinephrine, norepinephrine, 3,4-dihydroxyphenylalanine, and 3,4-dihydroxyphenylglycol were successfully quantified in mouse urine. PMID:25682335

  10. occupational exposure to aromatic hydrocarbons at a coke plant: Part II. Exposure assessment of volatile organic compounds.

    PubMed

    Bieniek, Grazyna; Kurkiewicz, Slawomir; Wilczok, Tadeusz; Klimek, Katarzyna; Swiatkowska, Longina; Lusiak, Agnieszka

    2004-05-01

    The objective of the study is to assess the external and internal exposures to aromatic hydrocarbons in the tar and oil naphthalene distillation processes at a coke plant. 69 workers engaged as operators in tar and oil naphthalene distillation processes and 25 non-exposed subjects were examined. Personal analyses of the benzene, toluene, xylene isomers, ethylbenzene, naphthalene, indan, indene and acenaphthene in the breathing zone air allowed us to determine the time weighted average exposure levels to the aromatic hydrocarbons listed above. The internal exposure was investigated by measurement of the urinary excretion of naphthols, 2-methylphenol and dimethylphenol isomers by means of gas chromatography with a flame ionization detection (GC/FID). Urine metabolites were extracted after enzymatic hydrolysis by solid-phase extraction with styrene-divinylbenzene resin. The time-weighted average concentrations of the hydrocarbons detected in the breathing zone air shows that the exposure levels of the workers are relatively low in comparison to the exposure limits. Statistically significant differences between average concentrations of aromatic hydrocarbons (benzene, toluene, xylene isomers) determined at the workplaces in the tar distillation department have been found. Concentrations of the naphthalene and acenaphthene detected in workers from the oil distillation department are higher that those from the tar distillation department. Concentrations of naphthols, 2-methoxyphenol and dimethylphenol isomers in the urine of occupationally exposed workers were significantly higher than those of non-exposed subjects. Concentrations of the 2-methoxyphenol and dimethylphenol isomers in urine were significantly higher for the tar distillation workers, whereas concentrations of naphthols were higher for the oil naphthalene distillation workers. Operators at the tar and naphthalene oil distillation processes are simultaneously exposed to a mixture of different hydrocarbons

  11. Laser-induced fluorescence detection strategies for sodium atoms and compounds in high-pressure combustors

    NASA Technical Reports Server (NTRS)

    Weiland, Karen J. R.; Wise, Michael L.; Smith, Gregory P.

    1993-01-01

    A variety of laser-induced fluorescence schemes were examined experimentally in atmospheric pressure flames to determine their use for sodium atom and salt detection in high-pressure, optically thick environments. Collisional energy transfer plays a large role in fluorescence detection. Optimum sensitivity, at the parts in 10 exp 9 level for a single laser pulse, was obtained with the excitation of the 4p-3s transition at 330 nm and the detection of the 3d-3p fluorescence at 818 nm. Fluorescence loss processes, such as ionization and amplified spontaneous emission, were examined. A new laser-induced atomization/laser-induced fluorescence detection technique was demonstrated for NaOH and NaCl. A 248-nm excimer laser photodissociates the salt molecules present in the seeded flames prior to atom detection by laser-induced fluorescence.

  12. Pyrolysis of simple coal model compounds containing aromatic carboxylic acids: Does decarboxylation lead to cross-linking?

    SciTech Connect

    Eskay, T.P.; Britt, P.F.; Buchanan, A.C. III

    1996-02-01

    The thermolysis of two aromatic carboxylic acids 1,2-(3,3`-dicarboxyphenyl)ethane (2) have been investigated at 400{degree} C as models of carboxylic acids in low rank coals. The major decomposition pathway observed is decarboxylation, which mainly occurs by an ionic pathway. This decarboxylation route does not lead to any significant amount of coupling or high molecular weight products that would be indicative of cross-linking products in coal. The pyrolysis of 1 and 2 will be investigated under a variety of conditions that better mimic the enviromment found in coal to further delineate the role that decarboxylation plays in coal cross-linking chemistry.

  13. On-road traffic emissions of polycyclic aromatic hydrocarbons and their oxy- and nitro- derivative compounds measured in road tunnel environments.

    PubMed

    Keyte, Ian J; Albinet, Alexandre; Harrison, Roy M

    2016-10-01

    Vehicular emissions are a key source of polycyclic aromatic compounds (PACs), including polycyclic aromatic hydrocarbons (PAHs) and their oxygenated (OPAH) and nitrated (NPAH) derivatives, in the urban environment. Road tunnels are a useful environment for the characterisation of on-road vehicular emissions, providing a realistic traffic fleet and a lack of direct sunlight, chemical reactivity and non-traffic sources. In the present investigation the concentrations of selected PAHs, OPAHs and NPAHs have been measured in the Parc des Princes Tunnel in Paris (PdPT, France), and at the Queensway Road Tunnel and an urban background site in Birmingham (QT, U.K). A higher proportion of semi-volatile (3-4 ring) PAH, OPAH and NPAH compounds are associated with the particulate phase compared with samples from the ambient environment. A large (~85%) decline in total PAH concentrations is observed between 1992 and 2012 measurements in QT. This is attributed primarily to the introduction of catalytic converters in the U.K as well as increasingly stringent EU vehicle emissions legislation. In contrast, NPAH concentrations measured in 2012 are similar to those measured in 1996. This observation, in addition to an increased proportion of (Phe+Flt+Pyr) in the observed PAH burden in the tunnel, is attributed to the increased number of diesel passenger vehicles in the U.K during this period. Except for OPAHs, comparable PAH and NPAH concentrations are observed in both investigated tunnels (QT and PdP). Significant differences are shown for specific substances between PAC chemical profiles in relation with the national traffic fleet differences (33% diesel passenger cars in U.K. vs 69% in France and up to 80% taking into account all vehicle categories). The dominating and sole contribution of 1-Nitropyrene observed in the PdPT NPAH profile strengthens the promising use of this compound as a diesel exhaust marker for PM source apportionment studies. PMID:27312273

  14. The Geoglobus acetivorans Genome: Fe(III) Reduction, Acetate Utilization, Autotrophic Growth, and Degradation of Aromatic Compounds in a Hyperthermophilic Archaeon

    PubMed Central

    Mardanov, Andrey V.; Slododkina, Galina B.; Slobodkin, Alexander I.; Beletsky, Alexey V.; Gavrilov, Sergey N.; Kublanov, Ilya V.; Bonch-Osmolovskaya, Elizaveta A.; Skryabin, Konstantin G.

    2014-01-01

    Geoglobus acetivorans is a hyperthermophilic anaerobic euryarchaeon of the order Archaeoglobales isolated from deep-sea hydrothermal vents. A unique physiological feature of the members of the genus Geoglobus is their obligate dependence on Fe(III) reduction, which plays an important role in the geochemistry of hydrothermal systems. The features of this organism and its complete 1,860,815-bp genome sequence are described in this report. Genome analysis revealed pathways enabling oxidation of molecular hydrogen, proteinaceous substrates, fatty acids, aromatic compounds, n-alkanes, and organic acids, including acetate, through anaerobic respiration linked to Fe(III) reduction. Consistent with the inability of G. acetivorans to grow on carbohydrates, the modified Embden-Meyerhof pathway encoded by the genome is incomplete. Autotrophic CO2 fixation is enabled by the Wood-Ljungdahl pathway. Reduction of insoluble poorly crystalline Fe(III) oxide depends on the transfer of electrons from the quinone pool to multiheme c-type cytochromes exposed on the cell surface. Direct contact of the cells and Fe(III) oxide particles could be facilitated by pilus-like appendages. Genome analysis indicated the presence of metabolic pathways for anaerobic degradation of aromatic compounds and n-alkanes, although an ability of G. acetivorans to grow on these substrates was not observed in laboratory experiments. Overall, our results suggest that Geoglobus species could play an important role in microbial communities of deep-sea hydrothermal vents as lithoautotrophic producers. An additional role as decomposers would close the biogeochemical cycle of carbon through complete mineralization of various organic compounds via Fe(III) respiration. PMID:25416759

  15. Predicting trace organic compound breakthrough in granular activated carbon using fluorescence and UV absorbance as surrogates.

    PubMed

    Anumol, Tarun; Sgroi, Massimiliano; Park, Minkyu; Roccaro, Paolo; Snyder, Shane A

    2015-06-01

    This study investigated the applicability of bulk organic parameters like dissolved organic carbon (DOC), UV absorbance at 254 nm (UV254), and total fluorescence (TF) to act as surrogates in predicting trace organic compound (TOrC) removal by granular activated carbon in water reuse applications. Using rapid small-scale column testing, empirical linear correlations for thirteen TOrCs were determined with DOC, UV254, and TF in four wastewater effluents. Linear correlations (R(2) > 0.7) were obtained for eight TOrCs in each water quality in the UV254 model, while ten TOrCs had R(2) > 0.7 in the TF model. Conversely, DOC was shown to be a poor surrogate for TOrC breakthrough prediction. When the data from all four water qualities was combined, good linear correlations were still obtained with TF having higher R(2) than UV254 especially for TOrCs with log Dow>1. Excellent linear relationship (R(2) > 0.9) between log Dow and the removal of TOrC at 0% surrogate removal (y-intercept) were obtained for the five neutral TOrCs tested in this study. Positively charged TOrCs had enhanced removals due to electrostatic interactions with negatively charged GAC that caused them to deviate from removals that would be expected with their log Dow. Application of the empirical linear correlation models to full-scale samples provided good results for six of seven TOrCs (except meprobamate) tested when comparing predicted TOrC removal by UV254 and TF with actual removals for GAC in all the five samples tested. Surrogate predictions using UV254 and TF provide valuable tools for rapid or on-line monitoring of GAC performance and can result in cost savings by extended GAC run times as compared to using DOC breakthrough to trigger regeneration or replacement. PMID:25792436

  16. Homogeneous liquid-liquid extraction combined with high performance liquid chromatography-fluorescence detection for determination of polycyclic aromatic hydrocarbons in vegetables.

    PubMed

    Zhao, Xinna; Liu, Xiujuan; Zhao, Zhixu; Huang, Changjiang; Zhang, Minghua; Wang, Huili; Wang, Xuedong

    2009-06-01

    In this article, homogeneous liquid-liquid extraction (HOLLE), combined with HPLC-fluorescence detector (HPLC-FLD), has been developed for the extraction and determination of polycyclic aromatic hydrocarbons (PAHs) in vegetables. ACN was used as extraction solvent for the extraction of target analytes from vegetables. When the previous extraction process was over, the ACN extract was transferred to the water-immiscible organic phase, tetrachloroethane, used as extraction solvent in HOLLE procedures. Under the optimum conditions, repeatability was carried out by spiking PAHs at concentration level of 12.5 microg/kg, the RSDs varied between 1.1 and 8.5% (n = 3). The LODs, based on S/N of 3, ranged from 0.025 to 0.25 microg/kg. Relative recoveries of PAHs from cucumber and long crooked squash samples were in the range of 72.4-104.9% and 65.5-119.3%, respectively. Compared with the conventional extraction method, the proposed method has the advantage of being quick, easy to operate, and having low consumption of organic solvent. PMID:19479763

  17. Spectral imaging of the Orion Bar at 3.3, 8.4, and 11.3 microns: Comparison with a fluorescent polycyclic aromatic hydrocarbon model

    NASA Technical Reports Server (NTRS)

    Bregman, Jesse; Larson, Kristen; Rank, David; Temi, Pasquale

    1994-01-01

    Spectral images were obtained of the Orion Bar which sample polycyclic aromatic hydrocarbon (PAH) emission at 3.3, 8.4, and 11.3 micrometers. The images are strikingly different even though they all sample PAH emission. In particular, the 3.3 and 11.3 micrometers images sample PAH emission from C-H bonds, yet the 3.3 micrometers image contains many small bright knots while the 11.3 micrometers image is much more uniform. For comparison with a fluorescent PAH model, a data set was created from the measured intensities of 250 locations in each image. From the comparison, we conclude that: (1) the size distribution of PAHs varies within the Bar, with the bright 3.3 micrometers knots containing the largest proportion of small PAHs; (2) the points along the front of the Bar have emission cross sections characteristic of neutral PAHs while within the Bar, the emission cross sections are different, consistent with the PAHs being charged; (3) the PAHs along the front of the Bar are larger than average for the Bar; (4) emission along the back of the Bar is consistent with PAH emission in an attenuated UV radiation field; (5) there is no evidence for PAH dehydrogenation.

  18. Pollution characteristics of volatile organic compounds, polycyclic aromatic hydrocarbons and phthalate esters emitted from plastic wastes recycling granulation plants in Xingtan Town, South China

    NASA Astrophysics Data System (ADS)

    Huang, De-Yin; Zhou, Shun-Gui; Hong, Wei; Feng, Wei-Feng; Tao, Liang

    2013-06-01

    With the aim to investigate the main pollution characteristics of exhaust gases emitted from plastic waste recycling granulation plants, mainly volatile organic compounds (VOCs), polycyclic aromatic hydrocarbons (PAHs) and phthalate esters (PAEs) were analyzed in Xingtan Town, the largest distribution center of plastic waste recycling in China. Both inside and outside the plants, the total concentrations of volatile monocyclic aromatic hydrocarbons (MAHs), PAHs and PAEs ranged from 2000 to 3000 μg m-3, 450 to 1200 ng m-3, and 200 to 1200 ng m-3, respectively. Their concentration levels inside the plants were higher than those outside the plants, and PAHs and PAEs were mainly distributed in the gas-phase. Notably, highly toxic benzo[a]pyrene (BaP) could be detected inside the plants, and harmful PAEs could be detected not only inside but also outside the plants, although PAEs are non-volatile. The exhaust gas composition and concentration were related to the plastic feedstock and granulation temperature.

  19. Compound specific radiocarbon analysis as a tool to quantitatively apportion modern and fossil sources of polycyclic aromatic hydrocarbons in environmental matrices

    SciTech Connect

    Eglinton, T.I.: Pearson, A.; McNichol, A.P.

    1996-12-31

    The quantitative apportionment of multiple sources of toxic compounds in natural systems has been of substantial interest in recent years. Polycyclic aromatic hydrocarbons (PAHs), which represent one of the largest classes of suspected chemical carcinogens/mutagens, are one such example. The biogeochemistry of PAHs in the environment is extremely complex as a result of the multitude of potential sources (both anthropogenic and natural), differing reactivities and solubilities, and transport and depositional processes that control their provenance. PAHs sources can be broadly divided into two categories: (a) {open_quotes}Pyrogenic{close_quotes} PAHs from high-temperature processes (i.e., incomplete combustion (pyrolysis) of organic materials); (b) PAHs from lower temperature processes (i.e. uncombusted petroleum contamination). Pyrogenic PAHs can be further separated into fossil fuel (coal and petroleum) combustion sources, and biomass combustion sources (charcoal burning; cigarette smoking, forest/grass fires, barbeques etc.). Although a variety of criteria may be used to distinguish petroleum from combustion sources of polycyclic aromatic hydrocarbons (PAHs) in environmental samples, it is much more difficult to distinguish PAHs derived from modem (e.g. residential wood combustion) versus fossil fuel (e.g. coal combustion) pyrogenic sources. This paper describes results of isotope dating of a coal tar extract and and air particulate sample.

  20. Non-covalent interactions of nitrous oxide with aromatic compounds: Spectroscopic and computational evidence for the formation of 1:1 complexes

    NASA Astrophysics Data System (ADS)

    Cao, Qian; Gor, Gennady Y.; Krogh-Jespersen, Karsten; Khriachtchev, Leonid

    2014-04-01

    We present the first study of intermolecular interactions between nitrous oxide (N2O) and three representative aromatic compounds (ACs): phenol, cresol, and toluene. The infrared spectroscopic experiments were performed in a Ne matrix and were supported by high-level quantum chemical calculations. Comparisons of the calculated and experimental vibrational spectra provide direct identification and characterization of the 1:1 N2O-AC complexes. Our results show that N2O is capable of forming non-covalently bonded complexes with ACs. Complex formation is dominated by dispersion forces, and the interaction energies are relatively low (about -3 kcal mol-1); however, the complexes are clearly detected by frequency shifts of the characteristic bands. These results suggest that N2O can be bound to the amino-acid residues tyrosine or phenylalanine in the form of π complexes.

  1. Structure-activity relationship of genotoxic polycyclic aromatic nitro compounds: Further evidence for the importance of hydrophobicity and molecular orbital energies in genetic toxicity

    SciTech Connect

    Debnath, A.K.; Hansch, C. )

    1992-01-01

    A quantitative structure-activity relationship (QSAR) has been formulated for 15 polycyclic aromatic nitro compounds acting on E. coli PQ37. Upon damage of DNA by these substances [beta]-galactosidase is induced and can be easily assayed colorimetrically, hence, this is a short-term test for mutagenicity. The QSAR (log SOSIP = 1.07 log P - 1.57 e[sub LUMO] - 6.41) is strikingly similar to that found earlier with nitroaromatics acting in the Ames test (TA100) and differs significantly for that found using TA98 organisms. The QSAR brings out in a unique manner the underlying similarity in the two test systems. 24 refs., 2 tabs.

  2. An efficient nitration of light alkanes and the alkyl side-chain of aromatic compounds with nitrogen dioxide and nitric acid catalyzed by N-hydroxyphthalimide.

    PubMed

    Nishiwaki, Yoshiki; Sakaguchi, Satoshi; Ishii, Yasutaka

    2002-08-01

    Nitration of light alkanes and the alkyl side-chain of aromatic compounds with NO(2) and HNO(3) was successfully achieved by the use of N-hydroxyphthalimide (NHPI) as a catalyst under relatively mild conditions. For example, the nitration of propane with NO(2) catalyzed by NHPI at 100 degrees C for 14 h gave 2-nitropropane in good yield without formation of 1-nitropropane and cleaved products such as nitroethane and nitromethane. Various aliphatic nitroalkanes, which are difficult to prepare by conventional methods, could be selectively obtained by means of the present methodology by using NHPI as the key catalyst. In addition, the side-chain nitration of alkylbenzenes such as toluene was selectively carried out to lead to alpha-nitrotoluene without the ring nitration. The present reaction provides an efficient selective method for the nitration of light alkanes and alkylbenzenes, which has been very difficult to carry out so far. PMID:12153265

  3. Non-covalent interactions of nitrous oxide with aromatic compounds: Spectroscopic and computational evidence for the formation of 1:1 complexes

    SciTech Connect

    Cao, Qian; Gor, Gennady Y.; Krogh-Jespersen, Karsten; Khriachtchev, Leonid

    2014-04-14

    We present the first study of intermolecular interactions between nitrous oxide (N{sub 2}O) and three representative aromatic compounds (ACs): phenol, cresol, and toluene. The infrared spectroscopic experiments were performed in a Ne matrix and were supported by high-level quantum chemical calculations. Comparisons of the calculated and experimental vibrational spectra provide direct identification and characterization of the 1:1 N{sub 2}O-AC complexes. Our results show that N{sub 2}O is capable of forming non-covalently bonded complexes with ACs. Complex formation is dominated by dispersion forces, and the interaction energies are relatively low (about −3 kcal mol{sup −1}); however, the complexes are clearly detected by frequency shifts of the characteristic bands. These results suggest that N{sub 2}O can be bound to the amino-acid residues tyrosine or phenylalanine in the form of π complexes.

  4. Batch and Flow Photochemical Benzannulations Based on the Reaction of Ynamides and Diazo Ketones. Application to the Synthesis of Polycyclic Aromatic and Heteroaromatic Compounds

    PubMed Central

    Willumstad, Thomas P.; Haze, Olesya; Mak, Xiao Yin; Lam, Tin Yiu; Wang, Yu-Pu; Danheiser*, Rick L.

    2013-01-01

    Highly substituted polycyclic aromatic and heteroaromatic compounds are produced via a two-stage tandem benzannulation/cyclization strategy. The initial benzannulation step proceeds via a pericyclic cascade mechanism triggered by thermal or photochemical Wolff rearrangement of a diazo ketone. The photochemical process can be performed using a continuous flow reactor which facilitates carrying out reactions on a large scale and minimizes the time required for photolysis. Carbomethoxy ynamides as well as more ketenophilic bissilyl ynamines and N-sulfonyl and N-phosphoryl ynamides serve as the reaction partner in the benzannulation step. In the second stage of the strategy, RCM generates benzofused nitrogen heterocycles, and various heterocyclization processes furnish highly substituted and polycyclic indoles of types that were not available by using the previous cyclobutenone-based version of the tandem strategy. PMID:24116731

  5. Characterization of polar polycyclic aromatic compounds in a heavy-duty diesel exhaust particulate by capillary column gas chromatography and high-resolution mass spectrometry

    SciTech Connect

    Bayona, J.M.; Markides, K.E.; Lee, M.L.

    1988-12-01

    Polar normal-phase HPLC fractions of a heavy-duty diesel exhaust particulate, a National Bureau of Standards (NBS) standard reference material (SRM) 1650, were analyzed by capillary column GC coupled to both low- and high-resolution mass spectrometry (HRMS) using electron impact (EI) and negative ion chemical ionization (NICI). Over 80 polycyclic aromatic compounds (PAC), belonging to many different chemical classes (anhydrides, carboxaldehydes, diazaarenes, cyclic imides, nitrohydroxy-PAC, nitroaza-PAC, nitrodiaza-PAC, nitrolactones, and quinones) were tentatively identified. Ten of them were positively identified by comparison of retention times with authentic standards. Among them, phenazine and phthalic anhydride were positively identified for the first time in diesel exhaust particulates. In addition, cyclic imides and their alkylated derivatives were tentatively identified for the first time. Other novel polar chemical classes of PAC were evidenced by MICI MS using a direct-insertion probe.

  6. Reduction of nitro aromatic compounds in Fe(0)-CO{sub 2}-H{sub 2}O systems: Implications for groundwater remediation with iron metal

    SciTech Connect

    Agrawal, A.

    1995-07-01

    The properties of iron metal that make it useful in remediation of chlorinated solvents may also lead to reduction of other groundwater contaminants such as nitro aromatic compounds (NACs). This possibility has been investigated in batch experiments using aqueous carbonate media to determine the kinetics and mechanism of nitro reduction by iron metal, and to learn more about the effect of precipitation on the reactivity of the metal surfaces under geochemical conditions. Nitrobenzene is reduced by iron under anaerobic conditions to aniline with nitrosobenzene as an intermediate product. Detectable amounts of coupling products such as azobenzene and azoxybenzene were not found. First-order reduction rates are similar for nitrobenzene and nitrosobenzene, but aniline appearance occurs more slowly. The nitro reduction rate increased linearly with concentration of iron surface area, giving a specific reaction rate constant which is roughly 16-fold greater than has been reported for dehalogenation of carbon tetrachloride.

  7. Induction of aromatic amino acids and phenylpropanoid compounds in Scrophularia striata Boiss. cell culture in response to chitosan-induced oxidative stress.

    PubMed

    Kamalipourazad, Maryam; Sharifi, Mohsen; Maivan, Hassan Zare; Behmanesh, Mehrdad; Chashmi, Najmeh Ahmadian

    2016-10-01

    Manipulation of cell culture media by elicitors is one of most important strategies to inducing secondary metabolism for the production of valuable metabolites. In this investigation, inducing effect of chitosan on physiological, biochemical, and molecular parameters were investigated in cell suspension cultures of Scrophularia striata Boiss. The results showed that chitosan concentration and time of elicitation are determinants of the effectiveness of the elicitor. Accumulation of aromatic amino acids (phenylalanine [Phe] and tyrosine [Tyr]), phenylpropanoid compounds (phenolic acids [PAs] and echinacoside [ECH]), hydrogen peroxide (H2O2) production, phenylalanine ammonia-lyase (PAL) activity and gene expression, and antioxidant enzymes (superoxide dismutase [SOD], peroxidase [POX], catalase [CAT]) activities were altered by changing the exposure time of elicitation. Results showed that, upon elicitation with chitosan, oxidative events were induced, antioxidant responses of S. striata cells were boosted through enhanced activity of an effective series of scavenging enzymes (SOD, CAT, and POX), and biosynthesis of non-enzymatic antioxidants (ECH and PAs [cinnamic, p-coumaric and, caffeic acids]). The increase in amino acid content and PAL activity at early days of exposure to chitosan was related with rises in phenolic compounds. These results provide evidence that chitosan by up-regulation of PAL gene differentially improves the production of phenylpropanoid compounds, which are of medical commercial value with good biotechnological prospects. PMID:27392152

  8. Contributions of Selected Biogenic and Aromatic Compounds to the Formation of Tropospheric Secondary Organic Aerosol over Several Sites in the United States

    NASA Astrophysics Data System (ADS)

    Jaoui, M.; Kleindienst, T. E.; Lewandowski, M.; Offenberg, J. H.; Corse, E. W.; Gerald, T.; Edney, E.

    2009-12-01

    The National Exposure Research Laboratory of the U.S. Environmental Protection Agency recently undertook an integrated laboratory and field research effort to better understand the contribution of biogenic and aromatic hydrocarbons to the formation of submicron ambient secondary organic aerosol (SOA). In the laboratory, isoprene, α-pinene, β-caryophyllene, 1,3-butadiene, 2-methyl-3-buten-2-ol, benzene, and toluene were individually irradiated under a wide range of conditions in a photochemical reaction chamber in the presence of nitrogen oxide (NOx). These hydrocarbons are thought to contribute to ambient SOA formation. In field studies conducted in Research Triangle Park, NC; Duke Forest in Chapel Hill, NC; Atlanta, GA; Pensacola, FL; Birmingham and Centerville, AL; Riverside, CA; Detroit, MI; Northbrook, East St. Louis and Bondville, IL; and Cincinnati, OH, ambient PM2.5 samples were collected for various periods between 2003 and 2006. The SOA collected from these laboratory experiments and the ambient PM2.5 samples were analyzed for organic carbon (OC) concentration and for organic tracer compounds by GC-MS using BSTFA derivatization for their identification and quantification. An organic tracer-based method was developed for estimating ambient SOA concentrations from individual SOA precursors to allow an assessment of SOA model predictions with ambient data. The results show that several major reaction products detected in SOA formed in the laboratory photooxidations were among the major compounds detected in field samples, effectively connecting laboratory and field results. Using the tracer-based method, the contributions of isoprene and monoterpenes to SOA formation show strong seasonal dependencies. However, no clear seasonal variations were observed for sesquiterpenes and aromatic hydrocarbons. The contribution of 2-methyl-3-buten-2-ol to ambient SOA was found to be not only season dependent but also higher in locations dominated by conifers, which are

  9. Trimerization of aromatic nitriles

    NASA Technical Reports Server (NTRS)

    Hsu, L. C. (Inventor)

    1977-01-01

    Triazine compounds and cross-linked polymer compositions were made by heating aromatic nitriles to a temperature in the range of about 100 C to about 700 C, in the presence of a catalyst or mixture of catalysts. Aromatic nitrile-modified (terminated and/or appended) imide, benzimidazole, imidazopyrrolone, quinoxaline, and other condensation type prepolymers or their precopolymers were made which were trimerized with or without a filler by the aforementioned catalytic trimerization process.

  10. Separation and identification of highly fluorescent compounds derived from trans-resveratrol in the leaves of Vitis vinifera infected by Plasmopara viticola.

    PubMed

    Tříska, Jan; Vrchotová, Naděžda; Olejníčková, Julie; Jílek, Rudolf; Sotolář, Radek

    2012-01-01

    A method for identification of highly fluorescent compounds in vine leaves infected by Plasmopara viticola was developed using reversed phase liquid chromatography with simultaneous diode array and fluorometric detection. Fluorescent compounds were extracted from leaves with a methanol-water mixture (70:30). Separation by HPLC was performed using a C(18) column and gradient elution with water-acetonitrile mixtures (20-80% of acetonitrile). The main unknown fluorescent compound was identified by line spectral comparison with a standard obtained by UV photoisomerization of trans-resveratrol glucoside, and its structure was confirmed by liquid chromatography-mass spectrometry. Identification and structural elucidation of the fluorescent compound in the leaves of Vitis vinifera allows early detection of Plasmopara viticola invasion. PMID:22395406

  11. Fluorescence spectroscopy as a specific tool for the interaction study of two surfactants with natural and synthetic organic compounds

    NASA Astrophysics Data System (ADS)

    Jung, Aude-Valérie; Frochot, Céline; Bersillon, Jean-Luc

    2016-04-01

    Four different techniques were used to study the binding of cationic cetyltrimethylammonium bromide (CTAB) and non-ionic nonylphenylethoxyl (NPE) surfactants to three synthetic organic components that mimic humic-like aggregates and to two natural aggregated humic substances (HS) extracted from aquatic suspended matter. The composition of synthetic organic components were chosen to be similar to high molecular weight highly processed terrigenous HS and low and high molecular weight less processed terrigenous (or aquatic terrigenous) HS. The natural HS were extracted under two different meteorological conditions (rainy and dry periods). No significant interaction between the non-ionic surfactant and any of the studied compounds was found. Concerning CTAB; pH, conductivity and turbidity measurements, along with fluorescence spectroscopy were combined to provide a better understanding of interactions between organic aggregates and the surfactant. The spectroscopic data show that a "highly processed terrigenous HS" fluorophore interacts in a different way with the cationic surfactant than an "aquatic terrigenous (or less processed terrigenous) HS" fluorophore does. Under similar conditions, some spectral changes in the fluorescence signal are correlated to changes in non-specific physical-chemical parameters (pH, turbidity, conductivity) for the organic compounds tested. The complexation mechanism is essentially governed by charge neutralization, which can be monitored specifically by the fluorescence of the organic moieties.

  12. Determination of low levels of polycyclic aromatic hydrocarbons in soil by high performance liquid chromatography with tandem fluorescence and diode-array detectors.

    PubMed

    Huang, Yujuan; Wei, Jing; Song, Jing; Chen, Mengfang; Luo, Yongming

    2013-08-01

    Risk assessment of polycyclic aromatic hydrocarbons (PAHs) contaminated soil and source apportionment require accurate analysis of the concentration of each PAH congener in the soil. However, determination of low level PAH congeners in soil is difficult because of similarity in the chemical properties of 16 PAHs and severe matrix interferences due to complex composition of soils. It is therefore imperative to develop a sensitive and accurate method for determination of low level PAHs in soil. In this work, high performance liquid chromatography equipped with fluorescence and diode-array detectors (HPLC-FLD-DAD) was used to determine the concentration of 16 PAHs in soil. The separation of the 16 PAHs was achieved by optimization of the mobile phase gradient elution program and FLD wavelength switching program. Qualitative analysis of the 16 PAHs was based on the retention time (RT) and each PAH specific spectrum obtained from DAD. In contrast, the quantitative analysis of individual PAH congeners was based on the peak areas at the specific wavelength with DAD and FLD. Under optimal conditions the detection limit was in the range 1.0-9.5 μg L(-1) for 16 PAHs with DAD and 0.01-0.1 μg L(-1) for 15 PAHs with FLD, and the RSD of PAHs was less than 5% with DAD and 3% with FLD. The spiked recoveries were in the range 61-96%, with the exception of NaP (<40%). The results show that HPLC-FLD-DAD can provide more accurate and reliable analysis of low level PAH congeners in soil samples. PMID:23659963

  13. Dissolution of biological samples in deep eutectic solvents: an approach for extraction of polycyclic aromatic hydrocarbons followed by liquid chromatography-fluorescence detection.

    PubMed

    Helalat-Nezhad, Zahra; Ghanemi, Kamal; Fallah-Mehrjardi, Mehdi

    2015-05-15

    A novel sample preparation method based on the complete dissolution of marine biological samples in choline chloride-oxalic acid (ChCl-Ox) deep eutectic solvent was developed for fast and efficient extraction of eight polycyclic aromatic hydrocarbons (PAHs) using minimum volumes of cyclohexane. The extracted PAHs were purified and then measured by high-performance liquid chromatography-fluorescence detection (HPLC-FL). The effect of key parameters on extraction recoveries and precision was investigated. At optimized conditions, the studied samples were dissolved under atmospheric pressure in ChCl-Ox (1:2) at 55°C for 30min, which is considerably lower than the temperature used in the classical and current methods. After dissolution, it took approximately 20min to quantitatively extract the PAHs from ChCl-Ox using 5mL cyclohexane. Depending on the analyte, the developed method was linear over the calibration range 1.0-250, 2.0-250, and 5.0-250ngg(-1), with r(2)>0.996. The detection limits of the method were between 0.50 and 3.08ngg(-1). The intra-day and inter-day precisions (based on the relative standard deviation, n=5) of the spiked PAHs at a concentration level of 50ngg(-1) were better than 12.6% and 13.3%, respectively. Individual PAH recoveries from spiked marine fish and macroalgae samples were in the range of 71.6% to 109.6%. For comparison, the spiked samples were also subjected to the Soxhlet extraction method. The simplicity of the procedure, high extraction efficiency, short analysis time, and use of safe and inexpensive components suggest the proposed method has a high potential for utilization in routine trace PAH analysis in biological samples. PMID:25857544

  14. Fluorescence properties of flavonoid compounds. Quantification in paprika samples using spectrofluorimetry coupled to second order chemometric tools.

    PubMed

    Monago-Maraña, Olga; Durán-Merás, Isabel; Galeano-Díaz, Teresa; Muñoz de la Peña, Arsenio

    2016-04-01

    The influence of pH on the fluorescence of flavonoid compounds was investigated and the highest fluorescence emission was obtained in basic medium. Selected conditions to improve this signal were: pH 9.5, 0.14 M Britton Robinson buffer and methanol between 5% and 10%. The excitation-emission fluorescence matrices of a set of 36 samples of Spanish paprika were analyzed by means of parallel factor analysis (PARAFAC). Thus, the profiles of possible fluorescence components (PARAFAC loadings) were obtained. One of these profiles was identified by matching PARAFAC scores with LC analysis on the same samples. Two clusters of samples were obtained when score values were plotted against each other. Spectrofluorimetry coupled to second order multivariate calibration methods, as unfolded-partial least squares with residual bilinearization (U-PLS/RBL) and multidimensional-partial least-squares with residual bilinearization (N-PLS/RBL), was investigated to quantify quercetin and kaempferol in those samples. Good results were obtained for quercetin by this approach. PMID:26593589

  15. 18O incorporation in the oxidation of N-methylcarbazole by lignin peroxidase and a model compound: a mechanistic insight into the oxidative N-demethylation of aromatic tertiary amines.

    PubMed

    Baciocchi, Enrico; Gerini, Maria Francesca; Lapi, Andrea

    2002-05-01

    Using 18O labelled reactants and/or solvent, the origin of the oxygen in the products of the oxidation of N-methylcarbazole by H2O2 catalysed by lignin peroxidase and a model compound has been determined, so getting important information about the mechanism of the oxidative N-demethylation of aromatic tertiary amines. PMID:12123061

  16. The chemistry of aromatic osmacycles.

    PubMed

    Cao, Xiao-Yu; Zhao, Qianyi; Lin, Zhiqun; Xia, Haiping

    2014-02-18

    Aromatic compounds, such as benzene and its derivatives, porphyrins, fullerenes, carbon nanotubes, and graphene, have numerous applications in biomedicine, materials science, energy science, and environmental science. Metalla-aromatics are analogues of conventional organic aromatic molecules in which one of the (hydro)carbon segments is formally replaced by an isolobal transition-metal fragment. Researchers have studied these transition-metal-containing aromatic molecules for the past three decades, particularly the synthesis and reactivity of metallabenzenes. Another focus has been the preparation and characterization of other metalla-aromatics such as metallafurans, metallapyridines, metallabenzynes, and more. Despite significant advances, remaining challenges in this field include the limited number of convenient and versatile synthetic methods to construct stable and fully characterized metalla-aromatics, and the relative shortage of new topologies. To address these challenges, we have developed new methods for preparing metalla-aromatics, especially those possessing new topologies. Our synthetic efforts have led to a large family of closely related metalla-aromatics known as aromatic osmacycles. This Account summarizes the synthesis and reactivity of these compounds, with a focus on features that are different from those of compounds developed by other groups. These osmacycles can be synthesized from simple precursors under mild conditions. Using these efficient methods, we have synthesized aromatic osmacycles such as osmabenzene, osmabenzyne, isoosmabenzene, osmafuran, and osmanaphthalene. Furthermore, these methods have also created a series of new topologies, such as osmabenzothiazole and osmapyridyne. Our studies of the reactivity of these osma-aromatics revealed unprecedented reaction patterns, and we demonstrated the interconversion of several osmacycles. Like other metalla-aromatics, osma-aromatics have spectroscopic features of aromaticity, such as

  17. Chlorinated, brominated, and perfluorinated compounds, polycyclic aromatic hydrocarbons and trace elements in livers of sea otters from California, Washington, and Alaska (USA), and Kamchatka (Russia)

    USGS Publications Warehouse

    Kannan, K.; Moon, H.-B.; Yun, S.-H.; Agusa, T.; Thomas, N.J.; Tanabe, S.

    2008-01-01

    Concentrations of organochlorine pesticides (DDTs, HCHs, and chlordanes), polychlorinated biphenyls (PCBs), polybrominated diphenyl ethers (PBDEs), polycyclic aromatic hydrocarbons (PAHs), perfluorinated compounds (PFCs), and 20 trace elements were determined in livers of 3- to 5-year old stranded sea otters collected from the coastal waters of California, Washington, and Alaska (USA) and from Kamchatka (Russia). Concentrations of organochlorine pesticides, PCBs, and PBDEs were high in sea otters collected from the California coast. Concentrations of DDTs were 10-fold higher in California sea otters than in otters from other locations; PCB concentrations were 5-fold higher, and PBDE concentrations were 2-fold higher, in California sea otters than in otters from other locations. Concentrations of PAHs were higher in sea otters from Prince William Sound than in sea otters from other locations. Concentrations of several trace elements were elevated in sea otters collected from California and Prince William Sound. Elevated concentrations of Mn and Zn in sea otters from California and Prince William Sound were indicative of oxidative stress-related injuries in these two populations. Concentrations of all of the target compounds, including trace elements, that were analyzed in sea otters from Kamchatka were lower than those found from the US coastal locations. ?? The Royal Society of Chemistry.

  18. Determination of aromatic sulphur compounds in heavy gas oil by using (low-)flow modulated comprehensive two-dimensional gas chromatography-triple quadrupole mass spectrometry.

    PubMed

    Franchina, Flavio Antonio; Machado, Maria Elisabete; Tranchida, Peter Quinto; Zini, Cláudia Alcaraz; Caramão, Elina Bastos; Mondello, Luigi

    2015-03-27

    The present research is focused on the development of a flow-modulated comprehensive two-dimensional gas chromatography-triple quadrupole mass spectrometry (FM GC × GC-MS/MS) method for the determination of classes of aromatic organic sulphur compounds (benzothiophenes, dibenzothiophenes, and benzonaphthothiophene) in heavy gas oil (HGO). The MS/MS instrument was used to provide both full-scan and multiple-reaction-monitoring (MRM) data. Linear retention index (LRI) ranges were used to define the MRM windows for each chemical class. Calibration solutions (internal standard: 1-fluoronaphthalene) were prepared by using an HGO sample, depleted of S compounds. Calibration information was also derived for the thiophene class (along with MRM and LRI data), even though such constituents were not present in the HGO. Linearity was satisfactory over the analyzed concentration range (1-100 mg/L); intra-day precision for the lowest calibration point was always below 17%. Accuracy was also satisfactory, with a maximum percentage error of 3.5% (absolute value) found among the S classes subjected to (semi-)quantification. The highest limit of quantification was calculated to be 299 μg/L (for the C1-benzothiophene class), while the lowest was 21 μg/L (for the C4-benzothiophene class). PMID:25704775

  19. The soluble methane mono-oxygenase of Methylococcus capsulatus (Bath). Its ability to oxygenate n-alkanes, n-alkenes, ethers, and alicyclic, aromatic and heterocyclic compounds.

    PubMed Central

    Colby, J; Stirling, D I; Dalton, H

    1977-01-01

    1. Methane mono-oxygenase of Methylococcus capsulatus (Bath) catalyses the oxidation of various substituted methane derivatives including methanol. 2. It is a very non-specific oxygenase and, in some of its catalytic properties, apparently resembles the analogous enzyme from Methylomonas methanica but differs from those found in Methylosinus trichosporium and Methylomonas albus. 3. CO is oxidized to CO2. 4. C1-C8 n-alkanes are hydroxylated, yielding mixtures of the corresponding 1- and 2-alcohols; no 3- or 4-alcohols are formed. 5. Terminal alkenes yield the corresponding 1,2-epoxides. cis- or trans-but-2-ene are each oxidized to a mixture of 2,3-epoxybutane and but-2-en-1-ol with retention of the cis or trans configuration in both products; 2-butanone is also formed from cis-but-2-ene only. 6. Dimethyl ether is oxidized. Diethyl ether undergoes sub-terminal oxidation, yielding ethanol and ethanal in equimolar amounts. 7. Methane mono-oxygenase also hydroxylates cyclic alkanes and aromatic compounds. However, styrene yields only styrene epoxide and pyridine yields only pyridine N-oxide. 8. Of those compounds tested, only NADPH can replace NADH as electron donor. PMID:411486

  20. Field-scale investigations on the biodegradation of chlorinated aromatic compounds and HCH in the subsurface environment

    NASA Astrophysics Data System (ADS)

    Feidieker, Doris; Kämpfer, Peter; Dott, Wolfgang

    1995-08-01

    The biological in situ remediation of a former pesticide production site, highly contaminated with chlorobenzenes, chlorophenols and hexachlorocyclohexanes, was studied for a period of one year. Field experiments testing the remediation technology were carried out in the subsurface to a depth of 5.5 m. Detailed monitoring of several chemical and microbiological parameters was made in order to evaluate the remediation success. The initial pollution of this site ranged from 0.03-0.30 g EOX (extractable halogenated organic compounds)/kg soil in the saturated layer to 1-20 g kg -1 EOX in the unsaturated layer, whereas the impounded water was polluted with 8-13 mg L -1 AOX (adsorbable halogenated organic compounds). No significant decrease of the pollutants in the subsoil was observed, although oxygen and nutrients were supplied in sufficient concentrations. In contrast, several of the chlorinated organic compounds were eliminated from the water treatment plant, either by physical or biological processes. Based on measurements of AOX in different parts of the plant, 26% of the pollutants was found adsorbed on the activated carbon and 3% was found in the sludge of the filter back-wash. Dependent on these measurements, elimination of ˜ 70% of the pollutants was attributed to microbial degradation. The latter fact is supported by oxygen consumption data, by increase in the microbial counts and by changes in the distribution of the pollutants in the plant effluent. Among the chlorobenzenes, 1,2,4-trichlorobenzene, and among the hexachlorocyclohexanes, a-hexachlorocyclohexane were eliminated preferentially. The results suggest that an in situ remediation of a site polluted with chlorinated organic compounds cannot be recommended; however, an on site circulation water treatment is possible by a combination of physical and biological processes.

  1. Achieving second order advantage with multi-way partial least squares and residual bi-linearization with total synchronous fluorescence data of monohydroxy-polycyclic aromatic hydrocarbons in urine samples.

    PubMed

    Calimag-Williams, Korina; Knobel, Gaston; Goicoechea, H C; Campiglia, A D

    2014-02-01

    An attractive approach to handle matrix interference in samples of unknown composition is to generate second- or higher-order data formats and process them with appropriate chemometric algorithms. Several strategies exist to generate high-order data in fluorescence spectroscopy, including wavelength time matrices, excitation-emission matrices and time-resolved excitation-emission matrices. This article tackles a different aspect of generating high-order fluorescence data as it focuses on total synchronous fluorescence spectroscopy. This approach refers to recording synchronous fluorescence spectra at various wavelength offsets. Analogous to the concept of an excitation-emission data format, total synchronous data arrays fit into the category of second-order data. The main difference between them is the non-bilinear behavior of synchronous fluorescence data. Synchronous spectral profiles change with the wavelength offset used for sample excitation. The work presented here reports the first application of total synchronous fluorescence spectroscopy to the analysis of monohydroxy-polycyclic aromatic hydrocarbons in urine samples of unknown composition. Matrix interference is appropriately handled by processing the data either with unfolded-partial least squares and multi-way partial least squares, both followed by residual bi-linearization. PMID:24456595

  2. Biodegradation of nitrogen- and oxygen-containing aromatic compounds in groundwater from an oil-contaminated aquifer

    NASA Astrophysics Data System (ADS)

    Jensen, Bjørn K.; Arvin, Erik; Gundersen, Anders T.

    1988-09-01

    The aerobic biodegradation of oxygen and nitrogen heterocycles and o-cresol by subsurface bacteria in groundwater from an oil contaminated site at Zealand, Denmark, was compared to the biodegradation of these compounds in laboratory adapted suspended and fixed-film cultures. The aquifer at the abstraction site had a relatively high redox potential, since it contained nitrate. The groundwater (i.e. without the soil phase) had a high biodegradation potential for dibenzofuran, indole, quinoline, flourenone and o-cresol. All the compounds were degraded in groundwater within 5-15 days from an initial concentration of about 0.5 mg L -1 in both mixed substrate and single substrate experiments with an initial ATP concentration of 0.2 ng mL -1. Pyrrole, however, was not degraded in groundwater within 55 days in the mixed substrate experiment and very slowly, after a lag period of 20 days, in the single substrate experiment. The biodegadability picture found for groundwater in the mixed substrate experiment was similar to the results found with laboratory adapted suspended and fixed-film cultures. None of the compounds had any inhibitory effect on the biodegradation of naphthalene.

  3. Detection of organophosphorus compound based on a sol-gel silica planar waveguide doped with a green fluorescent protein and an organophosphorus hydrolase

    NASA Astrophysics Data System (ADS)

    Enami, Y.; Tsuchiya, K.; Suye, S.

    2011-06-01

    In this letter, the authors report the real-time detection of an organophosphorus compound using a sol-gel silica planar waveguide doped with a green fluorescent protein and an organophosphorus hydrolase on a yeast-cell surface display. The waveguide was pumped at 488 nm, and it emitted green fluorescence at the far field. The green fluorescent light at 550 nm changed by 50% from the original power 1 min after application of the organophosphorus compound. The results enable the real-time detection of sarin and other biochemicals by using an in-line fiber sensor network.

  4. Elemental carbon and polycyclic aromatic compounds in a 150-year sediment core from Lake Qinghai, Tibetan Plateau, China: influence of regional and local sources and transport pathways.

    PubMed

    Han, Y M; Wei, C; Bandowe, B A M; Wilcke, W; Cao, J J; Xu, B Q; Gao, S P; Tie, X X; Li, G H; Jin, Z D; An, Z S

    2015-04-01

    Elemental carbon (EC) and polycyclic aromatic compounds (PACs) are potential proxies for the reconstruction of change in human activities and the origin of air masses in historic times. In this study, the historic deposition of char and soot (the two subtypes of EC) and PACs in a 150-year sediment core from different topographic subbasins of Lake Qinghai on the Qinghai Tibetan Plateau (QTP) were reconstructed. The objective was to explore how the variations in the concentrations of EC and PACs, in the ratios of char to soot and of oxygenated polycyclic aromatic hydrocarbons (OPAHs) to parent PAHs, and in the composition of the PAC mixtures reflect historical changes in climate and human activity and the origin of air masses arriving at the QTP. The deposition fluxes of soot in the different subbasins were similar, averaging 0.18 (range of 0.15-0.25) and 0.16 (0.13-0.23) g m(-2) year(-1), respectively, but they varied for char (averaging 0.11 and 0.22 g m(-2) year(-1), respectively), suggesting ubiquitous atmospheric deposition of soot and local river inputs of char. The different vertical distributions of the char/soot ratios in the different subbasins can be interpreted in terms of the different transport mechanisms of char and soot. An abrupt increase in soot concentrations since 1980 coincides with results from the QTP ice cores that were interpreted to be indicative of soot transport from South Asia. Similar concentration patterns of PAHs with soot and 9,10-anthraquinone/anthracene (9,10-AQ/ANT) ratios all >2.0 suggest regional PAC sources. Increasing PAH/soot ratios and decreasing 9,10-AQ/ANT ratios since the beginning of the 1970s indicate increasing local emissions. The historical trends of these diagnostic ratios indicate an increase in the fossil-fuel contribution since the beginning of the 1970s. The increase of perylene concentrations with increasing core depth and the ratio of perylene to its penta-aromatic isomers indicate that perylene originates

  5. Polyimidazoles via aromatic nucleophilic displacement

    NASA Technical Reports Server (NTRS)

    Connell, John W. (Inventor); Hergenrother, Paul M. (Inventor)

    1991-01-01

    Polyimidazoles (Pl) are prepared by the aromatic nucleophilic displacement reaction of di(hydroxyphenyl)imidazole monomers with activated aromatic dihalides or activated aromatic dinitro compounds. The reactions are carried out in polar aprotic solvents such as N,N-dimethylacetamide, sulfolane, N-methylpyrroldinone, dimethylsulfoxide, or diphenylsulfone using alkali metal bases such as potassium carbonate at elevated temperature under nitrogen. The di(hydroxyphenyl)imidazole monomers are prepared by reacting an aromatic aldehyde with a dimethoxybenzil or by reacting an aromatic dialdehyde with a methoxybenzil in the presence of ammonium acetate. The di(methoxyphenyl)imidazole is subsequently treated with aqueous hydrobromic acid to give the di(hydroxyphenyl)imidazole monomer. This synthetic route has provided high molecular weight Pl of new chemical structure, is economically and synthetically more favorable than other routes, and allows for facile chemical structure variation due to the availability of a large variety of activated aromatic dihalides and dinitro compounds.

  6. Polyimidazoles via aromatic nucleophilic displacement

    NASA Technical Reports Server (NTRS)

    Connell, John W. (Inventor); Hergenrother, Paul M. (Inventor)

    1992-01-01

    Polyimidazoles (PI) are prepared by the aromatic nucleophilic displacement reaction of di(hydroxyphenyl) imidazole monomers with activated aromatic dihalides or activated aromatic dinitro compounds. The reactions are carried out in polar aprotic solvents such as N,N-dimethyl acetamide, sulfolane, N-methylpyrrolidinone, dimethylsulfoxide, or diphenylsulfone using alkali metal bases such as potassium carbonate at elevated temperatures under nitrogen. The di(hydroxyphenyl) imidazole monomers are prepared by reacting an aromatic aldehyde with a dimethoxybenzil or by reacting an aromatic dialdehyde with a methoxybenzil in the presence of ammonium acetate. The di(methoxyphenyl) imidazole is subsequently treated with aqueous hydrobromic acid to give the di(hydroxphenyl) imidazole monomer. This synthetic route has provided high molecular weight PI of new chemical structure, is economically and synthetically more favorable than other routes, and allows for facile chemical structure variation due to the availability of a large variety of activated aromatic dihalides and dinitro compounds.

  7. Sediment contamination of residential streams in the metropolitan kansas city area, USA: Part I. distribution of polycyclic aromatic hydrocarbon and pesticide-related compounds

    USGS Publications Warehouse

    Tao, J.; Huggins, D.; Welker, G.; Dias, J.R.; Ingersoll, C.G.; Murowchick, J.B.

    2010-01-01

    This is the first part of a study that evaluates the influence of nonpoint-source contaminants on the sediment quality of five streams within the metropolitan Kansas City area, central United States. Surficial sediment was collected in 2003 from 29 sites along five streams with watersheds that extend from the core of the metropolitan area to its development fringe. Sediment was analyzed for 16 polycyclic aromatic hydrocarbons (PAHs), 3 common polychlorinated biphenyl mixtures (Aroclors), and 25 pesticide-related compounds of eight chemical classes. Multiple PAHs were detected at more than 50% of the sites, and concentrations of total PAHs ranged from 290 to 82,150 ??g/kg (dry weight). The concentration and frequency of detection of PAHs increased with increasing urbanization of the residential watersheds. Four- and five-ring PAH compounds predominated the PAH composition (73-100%), especially fluoranthene and pyrene. The PAH composition profiles along with the diagnostic isomer ratios [e.g., anthracene/(anthracene + phenanthrene), 0.16 ?? 0.03; fluoranthene/(fluoranthene + pyrene), 0.55 ?? 0.01)] indicate that pyrogenic sources (i.e., coal-tar-related operations or materials and traffic-related particles) may be common PAH contributors to these residential streams. Historical-use organochlorine insecticides and their degradates dominated the occurrences of pesticide-related compounds, with chlordane and dieldrin detected in over or nearly 50% of the samples. The occurrence of these historical organic compounds was associated with past urban applications, which may continue to be nonpoint sources replenishing local streams. Concentrations of low molecular weight (LMW; two or three rings) and high molecular weight (HMW; four to six rings) PAHs covaried along individual streams but showed dissimilar distribution patterns between the streams, while the historical pesticide-related compounds generally increased in concentration downstream. Correlations were noted

  8. Correlation Of Balkan Endemic Nephropathy With Fluorescent Organic Compounds In Shallow Groundwater

    NASA Astrophysics Data System (ADS)

    Goldberg, Marvin C.; Feder, Gerald L.; Radovanovic, Zoran

    1994-04-01

    Balkan endemic nephropathy (BEN) is a disease of intersitial nephropathy leading to end-stage renal failure. The disease occurs in persons living in villages on alluvial valleys of streams tributary to the Danube River in Rumania, Bulgaria and former Yugoslavia. The etiologic agent is not known, but a contaminant in shallow groundwater has become suspect. In this study, samples of drinking water from endemic and non-endemic village water supplies were analyzed by excitation/emission matrix (EEM) fluorescence spectroscopy. Spectra characteristic of groundwater from BEN households show elongated teardrop shapes in the fluorescence excitation/emission matrix. A sharp rise occurs in fluorescence emission between 380 and 400 nanometers (nm) and a trailing emission intensity from 400 to 550 nm. Spectra of groundwater samples from some BEN households have an additional excitation maxima at 300 nm, which further contributes to the emission intensity at 400 nm. Spectra of water samples from non-BEN households located in endemic villages show characteristics of BEN household waters, exhibiting the 250-nm excitation peak, even though the fluorophoric intensity is much less than that in samples from BEN household waters. Samples from non-endemic villages do not show the characteristic EEM spectra described as "teardrop shaped". The non-BEN households have lower concentrations of these fluorophores in the drinking water than the endemic households; hence, one of the factors in contracting the disease may be the concentration of these fluorescent materials in drinking water.

  9. Visualizing compound transgenic zebrafish in development: a tale of green fluorescent protein and KillerRed.

    PubMed

    Korzh, Vladimir; Teh, Cathleen; Kondrychyn, Igor; Chudakov, Dmitry M; Lukyanov, Sergey

    2011-03-01

    Optically translucent embryos of model vertebrates expressing transgenic fluorescent proteins provide a possibility to unravel developmental events, particularly when combined with live imaging. An introduction of transposon-mediated transgenesis resulted in generation of a number of transgenics expressing cytosolic green fluorescent protein in a tissue-specific manner. The recent generation of photodynamic and differentially tagged fluorescent proteins opened a possibility not only to mix-and-match living markers of different color, but also to employ them as powerful experimental tools for studies of cell physiology. Using this approach, transgenic lines expressing membrane-tagged KillerRed (memKR), a genetically encoded photosensitizer, with little or no inducible phototoxicity under confocal imaging were generated. Phototoxicity is only induced by intense green or white light generated by the mercury lamp in a widefield mode. Here, we discuss new ideas born from experimentation using the zebrafish Tol2 transposon-mediated enhancer trap transgenic lines expressing memKR. Because of accumulation on the cell membrane, memKR reveals fine details of cellular morphology. In combination with cytosolic green fluorescent protein, the multicolor in vivo imaging of memKR transgenics reveals complex developmental processes and provides a possibility to manipulate them by regulated generation of reactive oxygen species. PMID:21348774

  10. Urinary metabolites of a polycyclic aromatic hydrocarbon and volatile organic compounds in relation to lung cancer development in lifelong never smokers in the Shanghai Cohort Study

    PubMed Central

    Yuan, Jian-Min

    2014-01-01

    Exposures to polycyclic aromatic hydrocarbons (PAHs) from various environmental and occupational sources are considered a primary risk factor for lung cancer among lifelong never smokers, based largely on results from epidemiologic studies utilizing self-reported exposure information. Prospective, biomarker-based human studies on the role of PAH and other airborne carcinogens in the development of lung cancer among lifelong non-smokers have been lacking. We prospectively investigated levels of urinary metabolites of a PAH and volatile organic compounds in relation to lung cancer risk in a nested case–control study of 82 cases and 83 controls among lifelong never smokers of the Shanghai Cohort Study, a prospective cohort of 18 244 Chinese men aged 45–64 years at enrollment. We quantified three PAH metabolites: r-1,t-2,3,c-4-tetrahydroxy-1,2,3,4-tetrahydrophenanthrene (PheT), 3-hydroxyphenanthrene (3-OH-Phe) and total hydroxyphenanthrenes (total OH-Phe, the sum of 1-, 2-, 3- and 4-OH-Phe), as well as metabolites of the volatile organic compounds acrolein (3-hydroxypropyl mercapturic acid), benzene (S-phenyl mercapturic acid), crotonaldehyde (3-hydroxy-1-methylpropylmercapturic acid) and ethylene oxide (2-hydroxyethyl mercapturic acid). Urinary cotinine was also quantified to confirm non-smoking status. Compared with the lowest quartile, odds ratios (95% confidence intervals) for lung cancer risk for the highest quartile levels of PheT, 3-OH-Phe and total OH-Phe were 2.98 (1.13–7.87), 3.10 (1.12–7.75) and 2.59 (1.01–6.65) (all P trend < 0.05), respectively. None of the metabolites of the volatile organic compounds were associated with overall lung cancer risk. This study demonstrates a potentially important role of exposure to PAH in the development of lung cancer among lifelong never smokers. PMID:24148823

  11. A Fluorescent Microplate Assay Quantifies Bacterial Efflux and Demonstrates Two Distinct Compound Binding Sites in AcrB

    PubMed Central

    Ferrari, Annette; Rijnbrand, R.; Erwin, Alice L.

    2015-01-01

    A direct assay of efflux by Escherichia coli AcrAB-TolC and related multidrug pumps would have great value in discovery of new Gram-negative antibiotics. The current understanding of how efflux is affected by the chemical structure and physical properties of molecules is extremely limited, derived from antibacterial data for compounds that inhibit growth of wild-type E. coli. We adapted a previously described fluorescent efflux assay to a 96-well microplate format that measured the ability of test compounds to compete for efflux with Nile Red (an environment-sensitive fluor), independent of antibacterial activity. We show that Nile Red and the lipid-sensitive probe DiBAC4-(3) [bis-(1,3-dibutylbarbituric acid)-trimethine oxonol] can quantify efflux competition in E. coli. We extend the previous findings that the tetracyclines compete with Nile Red and show that DiBAC4-(3) competes with macrolides. The extent of the competition shows a modest correlation with the effect of the acrB deletion on MICs within the compound sets for both dyes. Crystallographic studies identified at least two substrate binding sites in AcrB, the proximal and distal pockets. High-molecular-mass substrates bound the proximal pocket, while low-mass substrates occupied the distal pocket. As DiBAC4-(3) competes with macrolides but not with Nile Red, we propose that DiBAC4-(3) binds the proximal pocket and Nile Red likely binds the distal site. In conclusion, competition with fluorescent probes can be used to study the efflux process for diverse chemical structures and may provide information as to the site of binding and, in some cases, enable rank-ordering a series of related compounds by efflux. PMID:25645845

  12. Selective extraction of genotoxic impurities and structurally alerting compounds using polymeric ionic liquid sorbent coatings in solid-phase microextraction: Alkyl halides and aromatics.

    PubMed

    Ho, Tien D; Joshi, Manishkumar D; Silver, Mark A; Anderson, Jared L

    2012-06-01

    A series of polymeric ionic liquids (PILs) possessing varied chemical makeup and composition were applied as selective solid-phase microextraction (SPME) sorbent coatings for the analysis of genotoxic impurities (GTIs) and related structurally alerting compounds, namely, alkyl halides and aromatics. In addition to exploiting two previously synthesized PILs as selective coatings, two new PILs, namely, N,N-didecyl-N-methyl-D-glucaminium poly(2-methyl-acrylic acid 2-[1-(3-{2-[2-(3-trifluoromethanesulfonylamino-propoxy)-ethoxy]-ethoxy}-propylamino)-vinylamino]-ethyl ester) (poly([DDMGlu][MTFSI])), and poly(1-vinyl-3-propylphenylimidazolium) chloride (poly([VPPIM][Cl])), were designed, synthesized, and their selectivity examined in the extraction of the selected analytes. The glucaminium-based coating was developed to exploit the hydrogen bond-acidic hydroxyl groups within the carbohydrate moiety of the PIL in addition to dispersive capabilities resulting from the cation and anion. The poly([VPPIM][Cl]) coating was tailored to possess π-π interaction capabilities through the phenyl functionality while also containing the hydrogen bond-basic chloride anion. Calibration studies were performed via headspace extraction to determine the sensitivity and limit of detection (LOD) for all analytes with respect to each PIL-based sorbent coating and compared to the polyacrylate (PA) and polydimethylsiloxane (PDMS) sorbent coatings. PILs containing the chloride anion exhibited high selectivity for aniline-based compounds. The glucaminium-based PIL exhibited good sensitivity for larger aliphatic alkyl halides. The poly(1-4-vinylbenzyl-3-hexadecylimidazolium) bis[(trifluoromethyl)sulfonyl] imide (poly([VBHDIM][NTf₂])) PIL coating demonstrated superior selectivity for larger aliphatic/aromatic analytes. The LODs of both commercial and PIL-based coatings for the two classes of GTIs ranged from low part-per-billion (ppb) to mid part-per-trillion (ppt) levels. Recovery studies were

  13. SOA Formation form the NO3 radicals Chemistry of Isoprene, Monoterpenes, Sesquiterpenes, Biogenic Oxygenated Compounds, and Aromatics

    NASA Astrophysics Data System (ADS)

    Kleindienst, T. E.; Jaoui, M.; Docherty, K.; Corse, E.; Offenberg, J. H.; Lewandowski, M.

    2011-12-01

    Volatile organic compounds (VOCs) are oxidized in the atmosphere primarily by hydroxyl radicals (OH) during daylight hours but also by nitrate radicals (NO3) during overnight, photochemically inactive periods. While reactions with OH have received considerable attention with regard to gas-phase reaction products and secondary organic aerosol (SOA) formation, less is known about the mechanisms and products resulting from nighttime NO3 reactions despite their potential for SOA formation. To date, there have been limited studies on the chemical characteristics of aerosol reaction products formed from VOCs oxidation with NO3, and few SOA reaction products have been identified. Nighttime reactions have nevertheless been incorporated into some air quality models despite the limited information available and substantial uncertainties which still exist. The National Exposure Research Laboratory of the U.S. Environmental Protection Agency recently undertook an integrated laboratory research effort to better understand the contribution of NO3 reactions to nighttime SOA formation. Isoprene, methacrolein, a-pinene, b-pinene, d-limonene, b-caryophyllene, farnesene, a-humulene, 2-methyl-3-buten-2-ol, toluene, m-xylene, and naphthalene were reacted with NO3 under a wide range of conditions in a series of separate photochemical reaction chamber experiments. These hydrocarbons are thought to contribute to ambient SOA formation. NO3 was formed through thermal decomposition of N2O5. The yield, physical characteristics, and composition of SOA formed in each experiment was analyzed by a suite of instruments including a scanning mobility particle sizer, a Sunset Labs semi continuous EC-OC monitor, a volatility differential mobility analyzer, a direct insertion probe-mass spectrometer, a high resolution time-of-flight aerosol mass spectrometer, and a gas-chromatography-mass spectrometer. To understand the relative contributions of nighttime versus daytime VOCs reactions, a similar

  14. Design, Synthesis, and Photophysical Properties of Pyrroloquinoline-Based Compounds Showing Strong Blue Fluorescence as Potential Dyes for Biomedical Applications.

    PubMed

    Carta, Davide; Balasso, Anna; Caliceti, Paolo; Ferlin, Maria Grazia

    2015-11-01

    A small library of 3-ethylpyrrolo[3,2-f]quinoline derivatives was synthesized to identify a novel class of dyes for use in biological studies. According to the spectroscopic analyses performed to evaluate the fluorimetric parameters of quantum yield and brightness, 7-methyl- and 6,7-dimethylpyrroloquinolin(9)one derivatives were found to be the best blue luminescent dyes for biological applications. To enhance the luminescence profiles and to obtain probes that could be conjugated to functional groups of supramolecular drug delivery systems, these compounds were further modified at position 3 to obtain 3-heptanoic acid and 3-aminohexylpyrroloquinolin(9)one methylated derivatives. The most brilliant 6,7-dimethyl-3-aminohexylpyrroloquinolinone hydrochloride was conjugated to pullulan, a biocompatible polysaccharide used to produce colloidal systems for drug delivery. Comparative studies showed that this compound can be properly exploited as a blue fluorescent label in biological investigations, namely cell trafficking and pharmacokinetics/biodistribution studies. These molecules possess higher fluorescence efficiency than commercial dyes in biological media, making them suitable alternatives to commercially available products in current use. PMID:26447862

  15. Cetyltrimethylammonium Bromide-Coated Fe₃O₄ Magnetic Nanoparticles for Analysis of 15 Trace Polycyclic Aromatic Hydrocarbons in Aquatic Environments by Ultraperformance, Liquid Chromatography With Fluorescence Detection.

    PubMed

    Wang, Hao; Zhao, Xiaoli; Meng, Wei; Wang, Peifang; Wu, Fengchang; Tang, Zhi; Han, Xuejiao; Giesy, John P

    2015-08-01

    Accurate determination of polycyclic aromatic hydrocarbons (PAHs) in surface waters is necessary for protection of the environment from adverse effects that can occur at concentrations which require preconcentration to be detected. In this study, an effective solid phase extraction (SPE) method based on cetyltrimethylammonium bromide (CTAB)-coated Fe3O4 magnetic nanoparticles (MNPs) was developed for extraction of trace quantities of PAHs from natural waters. An enrichment factor of 800 was achieved within 5 min by use of 100 mg of Fe3O4 MNPs and 50 mg of CTAB. Compared with conventional liquid-liquid extraction (LLE), C18 SPE cartridge and some newly developed methods, the SPE to determine bioaccessible fraction was more convenient, efficient, time-saving, and cost-effective. To evaluate the performance of this novel sorbent, five natural samples including rainwater, river waters, wastewater, and tap water spiked with 15 PAHs were analyzed by use of ultraperformance, liquid chromatography (UPLC) with fluorescence detection (FLD). Limits of determination (LOD) of PAHs (log Kow ≥ 4.46) ranged from 0.4 to 10.3 ng/L, with mean recoveries of 87.95 ± 16.16, 85.92 ± 10.19, 82.89 ± 5.25, 78.90 ± 9.90, and 59.23 ± 3.10% for rainwater, upstream and downstream river water, wastewater, and tap water, respectively. However, the effect of dissolved organic matter (DOM) on recovery of PAHs varied among matrixes. Because of electrostatic adsorption and hydrophobicity, DOM promoted adsorption of Fe3O4 MNPs to PAHs from samples of water from the field. This result was different than the effect of DOM under laboratory conditions. Because of competitive adsorption with the site of action on the surface of Fe3O4 MNPs for CTAB, recoveries of PAHs were inversely proportional to concentrations of Ca(2+) and Mg(2+). This novel sorbent based on nanomaterials was effective at removing PAHs at environmentally relevant concentrations from waters containing relevant concentrations of

  16. Standoff Detection of Volatile Organic Compounds In Air Using Laser Induced Fluorescence

    NASA Astrophysics Data System (ADS)

    Clark, Jerry; Alexander, Alonzo; Wiggins, Delonia; Williams, Sydney; Akpovo, Charlemagne; Mezonlin, Ephrem; Johnson, Joseph, III; CenterPlasma Science; Technology (CePaST) Team

    2011-10-01

    The use of laser-induced fluorescence has proven to be an excellent method of detecting important intermediates in turbulent systems. However, Acetylene detection in air at ambient temperatures has proven more challenging. Molecular spectra were collected in laser induced acetylene plasmas using a 250 mJ Nd:YAG laser and an optical parametric oscillator (OPO) to achieve the 260 nm wavelength and greater than 3 mJ energy necessary to excite acetylene molecules. The acetylene laser-induced fluorescence excitation was observed at the 228 nm wavelength. Using various concentration ratios, acetylene was mixed with air to specifically determine the capabilities of standoff acetylene detection at atmospheric pressure. These results will lead to further research and development of turbulence based battlefield ready detection devices. Research supported in part by NSF grants to FAMU.

  17. Influence of parasitism in dogs on their serum levels of persistent organochlorine compounds and polycyclic aromatic hydrocarbons.

    PubMed

    Henríquez-Hernández, Luis A; Carretón, Elena; Camacho, María; Montoya-Alonso, José Alberto; Boada, Luis D; Valerón, Pilar F; Cordón, Yaiza Falcón; Almeida-González, Maira; Zumbado, Manuel; Luzardo, Octavio P

    2016-08-15

    Persistent organochlorine pollutants (POPs) are toxic chemicals, which accumulate in humans and animals, as only few species have the capability of eliminating them. However, some authors have pointed to the possibility that certain species of invertebrates (i.e. nematodes) could metabolize this type of compounds. As certain species of nematodes act as parasites of vertebrates, this research was designed to explore the influence of some of the most common parasites of the dogs in their serum levels of 56 common POPs. The study included three groups of dogs (n=64), which were prospectively recruited in the island of Gran Canaria (Canary Islands, Spain): a) control animals, non-parasitized (serologically tested negative, n=24); b) dogs tested positive for intestinal parasites and negative for other parasites (n=24); and c) dogs tested positive for heartworm disease (Dirofilaria immitis) and negative for other parasites (n=16). The presence of Dirofilaria immitis was strongly associated with lower serum levels of a wide range of pollutant in their hosts (PCB congeners 28, 52, 118, 138, 153, and 180; hexachlorobenzene, lindane, aldrin, dieldrin, anthracene and pyrene). We also found an inverse association between the hosts' serum levels of PCBs and intestinal parasites. We did not find any association with DDT or its metabolites, but this might be explained by the recently suggested ability of dogs for the efficient metabolization of these compounds. According to the results of this study certain forms of parasitism would reduce the bioavailability of the major classes of POPs in dogs. However, further studies are needed to elucidate whether this phenomenon is due to a competence between parasites and hosts or could respond to a possible capability of parasitic nematodes for the metabolization of these POPs. PMID:27096633

  18. Phenotype fingerprinting suggests the involvement of single-genotype consortia in degradation of aromatic compounds by Rhodopseudomonas palustris

    SciTech Connect

    Karpinets, Tatiana V; Pelletier, Dale A; Pan, Chongle; Uberbacher, Edward C; Hettich, Robert {Bob} L; Samatova, Nagiza F

    2009-01-01

    Understanding of cellular processes involved in the anaerobic degradation of complex organic compounds by microorganisms is crucial for development of innovative biotechnologies for bioethanol production and for efficient degradation of toxic organic compounds. In natural environment the degradation is usually accomplished by syntrophic consortia comprised of different bacterial species. Here we show that the metabolically versatile phototrophic bacterium Rhodopseudomonas palustris may form its own syntrophic consortia, when it grows anaerobically on p-coumarate or benzoate as a sole carbon source. In the study we reveal the consortia from a comparison of large-scale measurements of mRNA and protein expressions under p-coumarate and benzoate degrading conditions using a novel computational approach referred as phenotype fingerprinting. In this approach marker genes for known R. palustris phenotypes are employed to calculate their expression from the gene and protein expressions in each studied condition. Subpopulations of the consortia are inferred from the expression of phenotypes and known metabolic modes of the R. palustris growth. We find that p-coumarate degrading condition leads to at least three R. palustris subpopulations utilizing p-coumarate, benzoate, and CO2 and H2. Benzoate degrading condition also produces at least three subpopulations utilizing benzoate, CO2 and H2, and N2 and formate. Communication among syntrophs and inter-syntrophic dynamics in each consortium are indicated by up-regulation of transporters and genes involved in the curli formation and chemotaxis. The photoautotrphic subpopulation found in both consortia is characterized by activation of two cbb operons and the uptake hydrogenase system. A specificity of N2-fixing subpopulation in the benzoate degrading consortium is the preferential activation of the vanadium nitrogenase over the molybdenum nitrogenase. The N2-fixing subpopulation in the consortium is confirmed by consumption of

  19. Bi-enzyme sensor for phenolic compounds with fluorescent read-out.

    PubMed

    Strianese, Maria; Zauner, Gerhild; Tabares, Leandro C; Tepper, Armand W J W; De Martino, Franco; Pellecchia, Claudio; Aartsma, Thijs J; Canters, Gerard W

    2013-10-25

    In this paper, the use of tyrosinase (Ty) from Streptomyces antibioticus, labeled with a fluorescent tag, in combination with soluble quinoprotein (PQQ-containing) glucose dehydrogenase (s-GDH) to measure trace amounts of phenols is explored. Proof of concept is provided by a series of experiments, which show a clear quantitative dependence of the response on the phenol concentration. One of the advantages of the detection system is that apart from a standard fluorimeter no further instrumentation is required. PMID:24115310

  20. Turn-On Fluorogenic and Chromogenic Detection of Small Aromatic Hydrocarbon Vapors by a Porous Supramolecular Host.

    PubMed

    Hatanaka, Sou; Ono, Toshikazu; Hisaeda, Yoshiio

    2016-07-18

    Benzene, toluene, ethylbenzene, the isomers of xylene, and trimethylbenzene are harmful volatile organic compounds and pose risks to human health and the environment. However, there are currently no effective chemosensors for vapors of these compounds. A porous supramolecular host for turn-on fluorogenic and chromogenic detection of the vapors of small aromatic hydrocarbons is presented. The host was constructed from a naphthalenediimide derivative that was supramolecularly connected to tris(pentafluorophenyl)borane. The amorphous powder form of the host allowed for effective accommodation of vapors of small aromatic hydrocarbons, resulting in a guest-dependent fluorescence emission. Increases in the fluorescence yield of 76-, 46-, and 37-fold were observed with toluene, benzene, and m-xylene, respectively. Negligible responses were obtained with common organic solvents. This simple supramolecular host could be applied as a useful sensor of small aromatic hydrocarbon vapors. PMID:27224939

  1. New bitter-masking compounds: hydroxylated benzoic acid amides of aromatic amines as structural analogues of homoeriodictyol.

    PubMed

    Ley, Jakob P; Blings, Maria; Paetz, Susanne; Krammer, Gerhard E; Bertram, Heinz-Jürgen

    2006-11-01

    Starting from the known bitter-masking flavanones eriodictyol and homoeriodictyol from herba santa some structurally related hydroxybenzoic acid amides of benzylamines were synthesized and evaluated as masking agents toward bitterness of caffeine by sensory methods. The closest structural relatives of homoeriodictyol, the hydroxybenzoic acid vanillylamides 5-9, were the most active and were able to reduce the bitterness of a 500 mg L(-1) caffeine solution by about 30% at a concentration of 100 mg L(-1). 2,4-Dihydroxybenzoic acid vanillylamide 7 showed a clear dose-dependent activity as inhibitor of the bitter taste of caffein between 5 and 500 mg L(-1). Additionally, it was possible to reduce the bitterness of quinine and salicine but not of the bitter peptide N-l-leucyl-l-tryptophan. Combinations of homoeriodictyol and amide 7 showed no synergistic or antagonistic changes in activity. The results for model compound 7 suggested that the hitherto unknown masking mechanism is probably the same for flavanones and the new amides. In the future, the new amides may be alternatives for the expensive flavanones to create flavor solutions to mask bitterness of pharmaceuticals or foodstuffs. PMID:17061836

  2. Synergistic selective extraction of actinides(III) over lanthanides from nitric acid using new aromatic diorganyldithiophosphinic acids and neutral organophosphorus compounds

    SciTech Connect

    Modolo, G.; Odoj, R.

    1999-01-01

    New aromatic dithiophosphinic acids (R{sub 2}PSSH) with R = C{sub 6}H{sub 5{sup {minus}}}, ClC{sub 6}H{sub 4{sup {minus}}}, FC{sub 6}H{sub 4{sup {minus}}} and CH{sub 3}C{sub 6}H{sub 4{sup {minus}}} were synthesized, characterized and tested as potential separating agents for trivalent actinides over lanthanides. The extraction of Am(III), Eu(III) and other lanthanides was carried out from nitric acid medium with mixtures of R{sub 2}PSSHs and neutral organophosphorus compounds. There was no detectable extraction when R{sub 2}PSSHs were used alone as extractants for either Am(III) or Eu(III) (D{sub Am,Eu} < 10{sup {minus}3}) under the experimental conditions used in this study. High separation factors (D{sub Am}/D{sub Eu} > 20) with D{sub Am} > 1 were achieved in the nitric acid range 0.1--1 mol/L by means of a synergistic mixture of bis(chlorophenyl)dithiophosphinic acid + tributylphosphate (TBP), trioctylphosphine oxide (TOPO) or tributylphosphine oxide (TBPO). The high radiation resistance (up to 10{sup 6} Gy absorbed {gamma}-doses) of the extractants was also demonstrated.

  3. Biomimetic synthesis of silver nanoparticles using the fish scales of Labeo rohita and their application as catalysts for the reduction of aromatic nitro compounds

    NASA Astrophysics Data System (ADS)

    Sinha, Tanur; Ahmaruzzaman, M.; Sil, A. K.; Bhattacharjee, Archita

    2014-10-01

    In this article, a cleaner, greener, cheaper and environment friendly method for the generation of self assembled silver nanoparticles (Ag NPs) applying a simple irradiation technique using the aqueous extract of the fish scales (which is considered as a waste material) of Labeo rohita is described. Gelatin is considered as the major ingredient responsible for the reduction as well as stabilisation of the self assembled Ag NPs. The size and morphology of the individual Ag NPs can be tuned by controlling the various reaction parameters, such as temperature, concentration, and pH. Studies showed that on increasing concentration and pH Ag NPs size decreases, while on increasing temperature, Ag NPs size increases. The present process does not need any external reducing agent, like sodium borohydride or hydrazine or others and gelatin itself can play a dual role: a ‘reducing agent' and ‘stabilisation agent' for the formation of gelatin-Ag NPs colloidal dispersion. The synthesized Ag NPs were characterised by Ultraviolet-Visible spectroscopy (UV-Vis), Transmission electron microscopy (TEM) and Selected area electron diffraction (SAED) analyses. The synthesized Ag NPs was used to study the catalytic reduction of various aromatic nitro compounds in aqueous and three different micellar media. The hydrophobic and electrostatic interaction between the micelle and the substrate is responsible for the catalytic activity of the nanoparticles in micelle.

  4. Biomimetic synthesis of silver nanoparticles using the fish scales of Labeo rohita and their application as catalysts for the reduction of aromatic nitro compounds.

    PubMed

    Sinha, Tanur; Ahmaruzzaman, M; Sil, A K; Bhattacharjee, Archita

    2014-10-15

    In this article, a cleaner, greener, cheaper and environment friendly method for the generation of self assembled silver nanoparticles (Ag NPs) applying a simple irradiation technique using the aqueous extract of the fish scales (which is considered as a waste material) of Labeo rohita is described. Gelatin is considered as the major ingredient responsible for the reduction as well as stabilisation of the self assembled Ag NPs. The size and morphology of the individual Ag NPs can be tuned by controlling the various reaction parameters, such as temperature, concentration, and pH. Studies showed that on increasing concentration and pH Ag NPs size decreases, while on increasing temperature, Ag NPs size increases. The present process does not need any external reducing agent, like sodium borohydride or hydrazine or others and gelatin itself can play a dual role: a 'reducing agent' and 'stabilisation agent' for the formation of gelatin-Ag NPs colloidal dispersion. The synthesized Ag NPs were characterised by Ultraviolet-Visible spectroscopy (UV-Vis), Transmission electron microscopy (TEM) and Selected area electron diffraction (SAED) analyses. The synthesized Ag NPs was used to study the catalytic reduction of various aromatic nitro compounds in aqueous and three different micellar media. The hydrophobic and electrostatic interaction between the micelle and the substrate is responsible for the catalytic activity of the nanoparticles in micelle. PMID:24835945

  5. Influence of extraction methodologies on the analysis of five major volatile aromatic compounds of citronella grass (Cymbopogon nardus) and lemongrass (Cymbopogon citratus) grown in Thailand.

    PubMed

    Chanthai, Saksit; Prachakoll, Sujitra; Ruangviriyachai, Chalerm; Luthria, Devanand L

    2012-01-01

    This paper deals with the systematic comparison of extraction of major volatile aromatic compounds (VACs) of citronella grass and lemongrass by classical microhydrodistillation (MHD), as well as modern accelerated solvent extraction (ASE). Sixteen VACs were identified by GC/MS. GC-flame ionization detection was used for the quantification of five VACs (citronellal, citronellol, geraniol, citral, and eugenol) to compare the extraction efficiency of the two different methods. Linear range, LOD, and LOQ were calculated for the five VACs. Intraday and interday precisions for the analysis of VACs were determined for each sample. The extraction recovery, as calculated by a spiking experiment with known standards of VACs, by ASE and MHD ranged from 64.9 to 91.2% and 74.3 to 95.2%, respectively. The extraction efficiency of the VACs was compared for three solvents of varying polarities (hexane, dichloromethane, and methanol), seven different temperatures (ranging from 40 to 160 degrees C, with a gradual increment of 20 degrees C), five time periods (from 1 to 10 min), and three cycles (1, 2, and 3 repeated extractions). Optimum extraction yields of VACs were obtained when extractions were carried out for 7 min with dichloromethane and two extraction cycles at 120 degrees C. The results showed that the ASE technique is more efficient than MHD, as it results in improved yields and significant reduction in extraction time with automated extraction capabilities. PMID:22816268

  6. Investigation of sulfonated aromatic compound (SAC) modification to nylon film. 2. Study of SAC sorption isotherm and atomic force microscopic characterization of nylon surfaces

    SciTech Connect

    Zhang, J.; Watson, B.A.; Keown, R.W.; Malone, C.P.; Barteau, M.A.

    1995-08-01

    Nylon 6 and nylon 66 films have been treated with aqueous sulfonated aromatic compound (SAC) solutions at concentrations ranging from 0.005 to 1.0 wt%. SAC uptakes at different treatment concentrations were measured and found to follow a BET isotherm. The surface morphologies of nylon film samples, including the original and SAC-treated films, have been characterized by atomic force microscopy (AFM). For untreated nylon 6 and nylon 66 films, AFM images show a randomly distributed fibrillar surface structure. Characteristic widths of fibrils in the nylon 66 and 6 films were 150-225 and 75-150 nm, respectively. For SAC-treated nylon films, the AFM images revealed that the surfaces of the films became covered with nodule-like features having a diameter range of 25-60 nm. AFM analysis provides evidence that SAC treatment deposited a surface coating on nylon films. AFM images of SAC-treated nylon films suggest a mechanism for stain resistance in which the SAC first forms a thin coating on the nylon via bondings between attractive groups in the SAC and nylon polymers. After treatment at increased SAC concentration, the surface is covered with nodule-like deposits which likely serve as a physical barrier to dye permeation. 20 refs., 8 figs.

  7. Development of urine standard reference materials for metabolites of organic chemicals including polycyclic aromatic hydrocarbons, phthalates, phenols, parabens, and volatile organic compounds.

    PubMed

    Schantz, Michele M; Benner, Bruce A; Heckert, N Alan; Sander, Lane C; Sharpless, Katherine E; Vander Pol, Stacy S; Vasquez, Y; Villegas, M; Wise, Stephen A; Alwis, K Udeni; Blount, Benjamin C; Calafat, Antonia M; Li, Zheng; Silva, Manori J; Ye, Xiaoyun; Gaudreau, Éric; Patterson, Donald G; Sjödin, Andreas

    2015-04-01

    Two new Standard Reference Materials (SRMs), SRM 3672 Organic Contaminants in Smokers' Urine (Frozen) and SRM 3673 Organic Contaminants in Non-Smokers' Urine (Frozen), have been developed in support of studies for assessment of human exposure to select organic environmental contaminants. Collaborations among three organizations resulted in certified values for 11 hydroxylated polycyclic aromatic hydrocarbons (OH-PAHs) and reference values for 11 phthalate metabolites, 8 environmental phenols and parabens, and 24 volatile organic compound (VOC) metabolites. Reference values are also available for creatinine and the free forms of caffeine, theobromine, ibuprofen, nicotine, cotinine, and 3-hydroxycotinine. These are the first urine Certified Reference Materials characterized for metabolites of organic environmental contaminants. Noteworthy, the mass fractions of the environmental organic contaminants in the two SRMs are within the ranges reported in population survey studies such as the National Health and Nutrition Examination Survey (NHANES) and the Canadian Health Measures Survey (CHMS). These SRMs will be useful as quality control samples for ensuring compatibility of results among population survey studies and will fill a void to assess the accuracy of analytical methods used in studies monitoring human exposure to these organic environmental contaminants. PMID:25651899

  8. Methods of analysis by the U.S. Geological Survey National Water Quality Laboratory : determination of polycyclic aromatic hydrocarbon compounds in sediment by gas chromatography/mass spectrometry

    USGS Publications Warehouse

    Olson, Mary C.; Iverson, Jana L.; Furlong, Edward T.; Schroeder, Michael P.

    2004-01-01

    A method for the determination of 28 polycyclic aromatic hydrocarbons (PAHs) and 25 alkylated PAH homolog groups in sediment samples is described. The compounds are extracted from sediment by solvent extraction, followed by partial isolation using high-performance gel permeation chromatography. The compounds are identified and uantitated using capillary-column gas chromatography/mass spectrometry. The report presents performance data for full-scan ion monitoring. Method detection limits in laboratory reagent matrix samples range from 1.3 to 5.1 micrograms per kilogram for the 28 PAHs. The 25 groups of alkylated PAHs are homologs of five groups of isomeric parent PAHs. Because of the lack of authentic standards, these homologs are reported semiquantitatively using a response factor from a parent PAH or a specific alkylated PAH. Precision data for the alkylated PAH homologs are presented using two different standard reference manuals produced by the National Institute of Standards and Technology: SRM 1941b and SRM 1944. The percent relative standard deviations for identified alkylated PAH homolog groups ranged from 1.55 to 6.98 for SRM 1941b and from 6.11 to 12.0 for SRM 1944. Homolog group concentrations reported under this method include the concentrations of individually identified compounds that are members of the group. Organochlorine (OC) pesticides--including toxaphene, polychlorinated biphenyls (PCBs), and organophosphate (OP) pesticides--can be isolated simultaneously using this method. In brief, sediment samples are centrifuged to remove excess water and extracted overnight with dichloromethan (95 percent) and methanol (5 percent). The extract is concentrated and then filtered through a 0.2-micrometer polytetrafluoroethylene syringe filter. The PAH fraction is isolated by quantitatively injecting an aliquot of sample onto two polystyrene-divinylbenzene gel-permeation chromatographic columns connected in series. The compounds are eluted with dichloromethane

  9. High extraction efficiency fiber coated with calix[4] open-chain crown ether for solid-phase microextraction of polar aromatic and aliphatic compounds.

    PubMed

    Liu, Mingming; Zeng, Zhaorui; Lei, Yun; Li, Haibing

    2005-11-01

    The calix[4] open-chain crown ether, 5,11,17,23-tetra-tert-butyl-25,27-di(2-allyloxyethoxyl)-26,28-dihydroxycalix[4]arene was synthesized and used for preparation of solid-phase microextraction (SPME) fibers of enhanced extraction efficiency. The new SPME coating made from calix[4] open-chain crown ether and hydroxyl-terminated silicone oil was developed with the aid of vinyltriethoxylsilane as bridge using sol-gel method and cross-linking technology. The efficiency of the novel fiber in the extraction of polar aromatic and aliphatic compounds, such as phenols, alcohols, and volatile fatty acids, was also investigated. Due to the introduction of the polar open-chain crown ether in calix[4]arene molecules, the calix[4] open-chain crown ether fiber showed much better selectivity and sensitivity to these polar compounds in comparison with calix[4]arene fiber. It also had superior extraction efficiency when compared to commercial poly(dimethylsiloxane)-divinylbenzene and polyacrylate fibers. Parts per billion to parts per trillion level detection limits were achieved for most of the analytes through SPME in conjunction with GC and flame ionization detector. The linear ranges were two to four orders of magnitude, and the RSD values were below 7% for all analytes. The novel fiber was applied to determine volatile alcohols and fatty acids in wine samples. The volatile-free wine prepared in this work was used to assure similar chemical environment for analytes in both calibration solutions and in real wine samples, thus compensating for possible matrix interferences. The established internal standard method using 4-methyl-2-pentanol as internal standard showed satisfactory accuracy and precision. PMID:16342796

  10. One-year study of polycyclic aromatic compounds at an urban site in Grenoble (France): Seasonal variations, gas/particle partitioning and cancer risk estimation.

    PubMed

    Tomaz, Sophie; Shahpoury, Pourya; Jaffrezo, Jean-Luc; Lammel, Gerhard; Perraudin, Emilie; Villenave, Eric; Albinet, Alexandre

    2016-09-15

    21 PAHs, 27 oxy-PAHs and 32 nitro-PAHs were measured every third day over a year in both gaseous (G) and particulate PM10 (P) phases in ambient air of Grenoble (France). Mean total concentrations (G+P) of PAHs and oxy-PAHs were in the same range and about 10ngm(-3). Nitro-PAHs were 50 to 100 times less concentrated averaging 100pgm(-3). Polycyclic aromatic compound (PAC) concentrations were 5 to 7 times higher in "cold" period (October to March) than in "warm" period (April to September). Seasonal variations may be explained by higher primary emissions from residential heating, especially biomass burning in "cold" season. Meteorological conditions and influence of the geomorphology around Grenoble, with the formation of thermal inversion layers leading to the stagnation of pollutants, were additional key parameters. Maximum individual PAC concentrations were observed during two PM10 pollution events in December and February-March. Chemical processes and secondary formation of oxy- and nitro-PAH were probably enhanced by the accumulation of the pollutants during these events. PAC gas/particle partitioning depended on compound molecular weight and vapour pressure. Gas/particle partitioning of oxy- and nitro-PAHs were evaluated using a multi-phase poly-parameter linear free energy relationship model. The PAC cancer risk was assessed using toxic equivalency factors available in the literature (19 PAHs, 10 nitro-PAHs and 1 oxy-PAH). Overall, particle-bound PACs contributed about 76% of the cancer risk. While PAHs accounted for most of the total PAC cancer risk, oxy- and nitro-PAHs could account for up to 24%. The risk quantification across substance classes is limited by toxicological data availability. PMID:27261422

  11. Occurrence, distribution and health risk from polycyclic aromatic compounds (PAHs, oxygenated-PAHs and azaarenes) in street dust from a major West African Metropolis.

    PubMed

    Bandowe, Benjamin A Musa; Nkansah, Marian Asantewah

    2016-05-15

    Scientific evidence suggests that the burden of disease on urban residents of sub-Saharan African Countries is increasing, partly as a result of exposure to elevated concentrations of toxic environmental chemicals. However, characterization of the levels, composition pattern and sources of polycyclic aromatic compounds (PACs) in environmental samples from African cities is still lacking. This study measured the PAHs, oxygenated-PAHs (OPAHs) and azaarene (AZAs) content of street dusts collected from Kumasi, Ghana (a major metropolis located in the tropical forest zone of West Africa). The ∑Alkyl+parent-PAHs, ∑OPAHs and ∑AZAs concentration in street dust averaged 2570ngg(-1) (range: 181-7600ngg(-1)), 833ngg(-1) (57-4200ngg(-1)) and 73ngg(-1) (3.3-240ngg(-1)), respectively. The concentrations of ∑Alkyl+parent-PAHs were strongly correlated (n=25) with ∑OPAHs (r=0.96, p<0.01) and ∑AZAs (r=0.94, p<0.01). The ∑OPAHs concentrations were also strongly correlated with ∑AZAs (r=0.91, p<0.01). Concentrations of individual PAHs in these street dusts were enriched at between 12 and 836 compared to their average concentrations in background soils from same city, demonstrating the high influence of traffic emissions. Several individual OPAHs and AZAs had higher concentrations than their related and often monitored parent-PAHs. The estimated incremental lifetime cancer risks due to the parent-PAHs in street dusts was >10(-6) indicating high risk of contracting cancer from exposure to street dust from Kumasi. The contribution of OPAHs, AZAs, and alkyl-PAHs in street dust to cancer risk could not be quantified because of lack of toxicity equivalency factors for these compounds; however this could be significant because of their high concentration and known higher toxicity of some polar PACs and alkyl-PAHs than their related parent-PAHs. PMID:26930316

  12. Characterizing baseline concentrations, proportions, and processes controlling deposition of river-transported bitumen-associated polycyclic aromatic compounds at a floodplain lake (Slave River Delta, Northwest Territories, Canada).

    PubMed

    Elmes, Matthew C; Wiklund, Johan A; Van Opstal, Stacey R; Wolfe, Brent B; Hall, Roland I

    2016-05-01

    Inadequate knowledge of baseline conditions challenges ability for monitoring programs to detect pollution in rivers, especially where there are natural sources of contaminants. Here, we use paleolimnological data from a flood-prone lake ("SD2", informal name) in the Slave River Delta (SRD, Canada), ∼ 500 km downstream of the Alberta oil sands development and the bitumen-rich McMurray Formation to identify baseline concentrations and proportions of "river-transported bitumen-associated indicator polycyclic aromatic compounds" (indicator PACs; Hall et al. 2012) and processes responsible for their deposition. Results show that indicator PACs are deposited in SD2 by Slave River floodwaters in concentrations that are 45 % lower than those in sediments of "PAD31compounds", a lake upstream in the Athabasca Delta that receives Athabasca River floodwaters. Lower concentrations at SD2 are likely a consequence of sediment retention upstream as well as dilution by sediment influx from the Peace River. In addition, relations with organic matter content reveal that flood events dilute concentrations of indicator PACs in SD2 because the lake receives high-energy floods and the lake sediments are predominantly inorganic. This contrasts with PAD31 where floodwaters increase indicator PAC concentrations in the lake sediments, and concentrations are diluted during low flood influence intervals due to increased deposition of lacustrine organic matter. Results also show no significant differences in concentrations and proportions of indicator PACs between pre- (1967) and post- (1980s and 1990 s) oil sands development high flood influence intervals (t = 1.188, P = 0.279, d.f. = 6.136), signifying that they are delivered to the SRD by natural processes. Although we cannot assess potential changes in indicator PACs during the past decade, baseline concentrations and proportions can be used to enhance ongoing monitoring efforts. PMID:27071660

  13. Polyimidazoles Via Aromatic Nucleophilic Displacement

    NASA Technical Reports Server (NTRS)

    Connell, John W.; Hergenrother, Paul M.

    1990-01-01

    Experiments show variety of polyimidazoles prepared by aromatic nucleophilic displacement, from reactions of bisphenol imidazoles with activated difluoro compounds. Polyimidazoles have good mechanical properties making them suitable for use as films, moldings, and adhesives.

  14. Preparation of a novel ionic hybrid stationary phase by non-covalent functionalization of single-walled carbon nanotubes with amino-derivatized silica gel for fast HPLC separation of aromatic compounds.

    PubMed

    Aral, Hayriye; Çelik, K Serdar; Aral, Tarık; Topal, Giray

    2016-03-01

    Single-walled carbon nanotubes (SWCNTs) were immobilized on spherical silica gel with a 4-μm average particle size and a 60-Å average pore size. The amino-derivatized silica gel was non-covalently coated with carboxylated SW