Sequential lignin depolymerization by combination of biocatalytic and formic acid/formate treatment steps.

PubMed

Gasser, Christoph A; Čvančarová, Monika; Ammann, Erik M; Schäffer, Andreas; Shahgaldian, Patrick; Corvini, Philippe F-X

2017-03-01

Lignin, a complex three-dimensional amorphous polymer, is considered to be a potential natural renewable resource for the production of low-molecular-weight aromatic compounds. In the present study, a novel sequential lignin treatment method consisting of a biocatalytic oxidation step followed by a formic acid-induced lignin depolymerization step was developed and optimized using response surface methodology. The biocatalytic step employed a laccase mediator system using the redox mediator 1-hydroxybenzotriazole. Laccases were immobilized on superparamagnetic nanoparticles using a sorption-assisted surface conjugation method allowing easy separation and reuse of the biocatalysts after treatment. Under optimized conditions, as much as 45 wt% of lignin could be solubilized either in aqueous solution after the first treatment or in ethyl acetate after the second (chemical) treatment. The solubilized products were found to be mainly low-molecular-weight aromatic monomers and oligomers. The process might be used for the production of low-molecular-weight soluble aromatic products that can be purified and/or upgraded applying further downstream processes.

Weathering Patterns of Forensic Biomarker Compounds and PAHs in Coastal Marsh Sediment Samples since the 2010 Deepwater Horizon Oil Spill

NASA Astrophysics Data System (ADS)

Overton, E. B.; Meyer, B.; Miles, S.; Olson, G.; Adhikari, P. L.

2016-02-01

It has been well established that the composition of oil, when spilled into the marine environment, undergoes substantial changes caused by weathering. The general sequence of this compositional change begins with straight chain alkanes (the fastest to degrade), followed by low molecular weight branched and cyclic alkanes and, finally the aromatics. Most resistant to weathering are the higher molecular weight cyclic and branched alkanes (i.e., the "forensic biomarker compounds" such as the hopanes and steranes) and tri-aromatic ringed steroids. The composition of these biomarker compounds is particularly resistant to change because they are not affected by evaporative weathering, are not water soluble, and are not readily degraded by microbial and/or photo-oxidation. However, after extensive time in the environment, being subjected to numerous weathering factors, biomarker compositional patterns are beginning to exhibit significant changes. This presentation will describe the general weathering patterns of petroleum residues in sediment samples collected from marsh areas of coastal Louisiana over a five year period. Particular attention will focus on compositional changes that have been observed in the steranes and diasteranes compounds that traditionally have been considered the most resistant to compositional changes due to weathering.

Poly(N-arylenbenzimidazoles) via aromatic nucleophilic displacement

NASA Technical Reports Server (NTRS)

Connell, John W. (Inventor); Hergenrother, Paul M. (Inventor); Smith, Joseph G., Jr. (Inventor)

1995-01-01

Novel poly(N-arylenebenzimidazole)s (PNABIs) are prepared by the aromatic nucleophilic displacement reaction of novel di(hydroxyphenyl-N-arylene benzimidazole) monomers with activated aromatic dihalides or activated aromatic dinitro compounds. The polymerizations are carried out in polar aprotic solvents such as N-methyl-2-pyrrolidinone or N,N-dimethylacetamide using alkali metal bases such as potassium carbonate at elevated temperatures under nitrogen. The di(hydroxyphenyl N-arylenebenzimidazole) monomers are synthesized by reacting phenyl 4-hydroxybenzoate with bis(2-aminoanilino) arylenes in diphenylsulfone. Moderate molecular weight PNABIs of new chemical structures were prepared that exhibit a favorable combination of physical and mechanical properties. The use of the novel di(hydroxyphenyl N-arylenebenzimidazole)s permits a more economical and easier way to prepare PNABIs than previous routes.

Poly(N-arylenebenzimidazole)s via aromatic nucleophilic displacement

NASA Technical Reports Server (NTRS)

Connell, John W. (Inventor); Hergenrother, Paul M. (Inventor); Smith, Jr., Joseph G. (Inventor)

1996-01-01

Novel poly(N-arylenebenzimidazole)s (PNABls) are prepared by the aromatic nucleophilic displacement reaction of novel di(hydroxyphenyl-N-arylene benzimidazole) monomers with activated aromatic dihalides or activated aromatic dinitro compounds. The polymerizations are carried out in polar aprotic solvents such as N-methyl-2-pyrrolidinone or N,N-dimethylacetamide using alkali metal bases such as potassium carbonate at elevated temperatures under nitrogen. The di(hydroxyphenyl-N-arylenebenzimidazole) monomers are synthesized by reacting phenyl-4-hydroxybenzoate with bis(2-aminoanilino)arylenes in diphenylsulfone. Moderate molecular weight PNABIs of new chemical structures were prepared that exhibit a favorable combination of physical and mechanical properties. The use of the novel di(hydroxyphenyI-N-arylenebenzimidazole)s permits a more economical and easier way to prepare PNABIs than previous routes.

Evaluation of environmental levels of aromatic hydrocarbons in gasoline service stations by gas chromatography.

PubMed

Periago, J F; Zambudio, A; Prado, C

1997-08-22

The volume of gasoline sold in refuelling operations and the ambient temperature, can increase significantly the environmental levels of aromatic hydrocarbon vapours and subsequently, the occupational risk of gasoline service station attendants, specially in the case of benzene. We have evaluated the occupational exposure to aromatic hydrocarbons by means of personal-breathing-zone samples of gasoline vapours in a service station attendant population. This evaluation was carried out using diffusive samplers, in two periods at quite different temperatures (March and July). A significant relationship between the volume of gasoline sold during the shift and the ambient concentration of benzene, toluene, and xylenes was found for each worker sampled. Furthermore a significant difference was found between the time-weighted average concentration of aromatic compounds measured in March, with ambient temperatures of 14-15 degrees C and July, with temperatures of 28-30 degrees C. In addition, 20% of the population sampled in the last period were exposed to a time-weighted average concentration of benzene above the proposed Threshold Limit Value of 960 micrograms/m(3) of the American Conference of Governmental Industrial Hygienists (ACGIH).

Transformations of dissolved organic matter in a landfill leachate--a size exclusion chromatography/mass spectrometric approach.

PubMed

Persson, Linn; Alsberg, Tomas; Ledin, Anna; Odham, Göran

2006-08-01

The aim of the present study was to search for qualitative changes in the landfill leachate DOM along a groundwater gradient. The study was focused on DOM characteristics of importance for its interaction with pollutants, such as molecular weight distribution and aromaticity. It was concluded that the leachate DOM underwent substantial qualitative changes along the investigated gradient at the Vejen landfill, Denmark. The molecular weight decreased, the polydispersity increased, and the aromaticity varied with the lowest values found in the middle of the gradient. The high aromaticity in the end of the gradient may explain the higher DOM binding capacity towards hydrophobic compounds seen earlier in these samples. The relative abundance of ions with mass to charge ratio (m/z) of 600-1200 seemed to be very stable along the gradient, indicating that the observed qualitative changes of the DOM is mostly attributed to changes in the m/z 100-600 range. The DOM seemed to become more similar to fulvic acids present in uncontaminated groundwater with respect to molecular weight and polydispersity along the gradient.

Polycyclic aromatic hydrocarbons in oysters and sediments from the Yatsushiro Sea, Japan: comparison of potential risks among PAHs, dioxins and dioxin-like compounds in benthic organisms.

PubMed

Nakata, Haruhiko; Uehara, Kiriko; Goto, Yuta; Fukumura, Miki; Shimasaki, Hideyuki; Takikawa, Kiyoshi; Miyawaki, Takashi

2014-01-01

Polycyclic aromatic hydrocarbons (PAHs) were analyzed in oysters collected from 18 stations in the Yatsushiro Sea, western Japan. PAHs were detected in all samples analyzed, and the highest concentration (mean 230 ng/g wet weight) was found in oysters from Tanoura Bay. The high molecular weight PAHs to low molecular weight PAHs ratios in oysters from Tanoura Bay were higher than at other stations. Sediment samples collected from 42 stations in Tanoura Bay were analyzed for PAHs to understand their concentrations and distribution. Higher concentrations were found in sediment samples at two stations in the southern inner bay (mean 30,200 ng/g dry weight), which were approximately two orders of magnitude higher than at a reference site. These observations strongly suggest severe contamination and significant sources of PAHs in Tanoura Bay. Dioxins and dioxin-like compounds (PCDFs, and non- and mono-ortho coplanar PCBs) were analyzed in sediments from eight stations in Tanoura Bay. The concentrations were comparable to, or lower than, at the reference sites, suggesting that there are no specific sources of these compounds in this bay. PAH, dioxins and dioxin-like compounds DR-CALUX relative potencies (REP) were applied to the sediment concentrations to evaluate the potential for toxicological effects on benthic organisms. PAHs made the highest contribution to the total REP concentration, supplying 99% of the total REP, followed by PCDDs (0.18%), PCDFs (0.04%), and PCBs (<0.001%). In this area, PAHs appear to be the most important Ah receptor binding chemicals for potential toxicity to benthic species. © 2013 Published by Elsevier Inc.

Frog volatile compounds: application of in vivo SPME for the characterization of the odorous secretions from two species of Hypsiboas treefrogs.

PubMed

Brunetti, Andrés E; Merib, Josias; Carasek, Eduardo; Caramão, Elina B; Barbará, Janaina; Zini, Claudia A; Faivovich, Julián

2015-04-01

A novel in vivo design was used in combination with solid-phase microextraction (SPME) and gas chromatography/mass spectrometry (GC/MS) to characterize the volatile compounds from the skin secretion of two species of tree frogs. Conventional SPME-GC/MS also was used for the analysis of volatiles present in skin samples and for the analysis of volatiles present in the diet and terraria. In total, 40 and 37 compounds were identified in the secretion of Hypsiboas pulchellus and H. riojanus, respectively, of which, 35 were common to both species. Aliphatic aldehydes, a low molecular weight alkadiene, an aromatic alcohol, and other aromatics, ketones, a methoxy pyrazine, sulfur containing compounds, and hemiterpenes are reported here for the first time in anurans. Most of the aliphatic compounds seem to be biosynthesized by the frogs following different metabolic pathways, whereas aromatics and monoterpenes are most likely sequestered from environmental sources. The characteristic smell of the secretion of H. pulchellus described by herpetologists as skunk-like or herbaceous is explained by a complex blend of different odoriferous components. The possible role of the volatiles found in H. pulchellus and H. riojanus is discussed in the context of previous hypotheses about the biological function of volatile secretions in frogs (e.g., sex pheromones, defense secretions against predators, mosquito repellents).

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... Specific Chemical Substances § 721.775 Brominated aromatic com-pound (generic name). (a) Chemical... as a brominated aromatic compound (PMN P-84-824) is subject to reporting under this section for the...

Search for organic compounds in the lunar dust from the Sea of Tranquillity

USGS Publications Warehouse

Ponnamperuma, C.; Kvenvolden, K.; Chang, S.; Johnson, Richard; Pollock, G.; Philpott, D.; Kaplan, I.; Smith, J.; Schopf, J.W.; Gehrke, C.; Hodgson, G.; Breger, I.A.; Halpern, B.; Duffield, A.; Krauskopf, K.; Barghoorn, E.; Holland, H.; Keil, Klaus

1970-01-01

A sample of lunar dust was examined for organic compounds. Carbon detected in concentrations of 157 micrograms per gram had a δ13C per mil (PDB) value of + 20. Treatment with hydrochloric acid yielded hydrocarbons of low molecular weight, suggesting the presence of carbides. The gas chromatogram of the acylated and esterified derivatives of the hydrolyzate was similar to that obtained for the Pueblito de Allende meteorite. There were no detectable amounts of extractable high-molecular-weight alkanes, aromatic hydrocarbons, isoprenoid hydrocarbons, normal alkanes, fatty acids, amino acids, sugars, or nucleic acid bases. Traces of porphyrins were found, perhaps arising from rocket exhaust materials.

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.

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.

Salting-out assisted liquid-liquid extraction and partial least squares regression to assay low molecular weight polycyclic aromatic hydrocarbons leached from soils and sediments

NASA Astrophysics Data System (ADS)

Bressan, Lucas P.; do Nascimento, Paulo Cícero; Schmidt, Marcella E. P.; Faccin, Henrique; de Machado, Leandro Carvalho; Bohrer, Denise

2017-02-01

A novel method was developed to determine low molecular weight polycyclic aromatic hydrocarbons in aqueous leachates from soils and sediments using a salting-out assisted liquid-liquid extraction, synchronous fluorescence spectrometry and a multivariate calibration technique. Several experimental parameters were controlled and the optimum conditions were: sodium carbonate as the salting-out agent at concentration of 2 mol L- 1, 3 mL of acetonitrile as extraction solvent, 6 mL of aqueous leachate, vortexing for 5 min and centrifuging at 4000 rpm for 5 min. The partial least squares calibration was optimized to the lowest values of root mean squared error and five latent variables were chosen for each of the targeted compounds. The regression coefficients for the true versus predicted concentrations were higher than 0.99. Figures of merit for the multivariate method were calculated, namely sensitivity, multivariate detection limit and multivariate quantification limit. The selectivity was also evaluated and other polycyclic aromatic hydrocarbons did not interfere in the analysis. Likewise, high performance liquid chromatography was used as a comparative methodology, and the regression analysis between the methods showed no statistical difference (t-test). The proposed methodology was applied to soils and sediments of a Brazilian river and the recoveries ranged from 74.3% to 105.8%. Overall, the proposed methodology was suitable for the targeted compounds, showing that the extraction method can be applied to spectrofluorometric analysis and that the multivariate calibration is also suitable for these compounds in leachates from real samples.

Denitration of 2,4,6-trinitrotoluene in aqueous solutions using small-molecular-weight catalyst(s) secreted by Pseudomonas aeruginosa ESA-5.

PubMed

Stenuit, Ben; Eyers, Laurent; Rozenberg, Raoul; Habib-Jiwan, Jean-Louis; Matthijs, Sandra; Cornelis, Pierre; Agathos, Spiros N

2009-03-15

The denitration of 2,4,6-trinitrotoluene (TNT) can produce mono- or dinitro aromatic compounds susceptible to microbial mineralization. In the present study, denitration of TNT and other nitro aromatic compounds was investigated with a solid-phase extract obtained from the culture supernatant of Pseudomonas aeruginosa ESA-5 grown on a chemically defined aerobic medium. When the C18 solid-phase extract containing extracellular catalysts (EC) was incubated with TNT and NAD(P)H, we observed a significant release of nitrite. The concentration of nitrite released in the reaction medium was strongly dependent on the concentration of NAD(P)H and EC. Denitration also occurred with two TNT-related molecules, 2,4,6-trinitrobenzaldehyde, and 2,4,6-trinitrobenzyl alcohol. The release of nitrite was coupled with the formation of two polar metabolites, and mass spectrometry analyses indicated that each of these compounds had lost two nitro groups from the trinitro aromatic parent molecule. During this process, the production of toxic reduced TNT metabolites was minimal. The incubation of EC with TNT, NAD(P)H, and specific scavengers of reactive oxygen species suggested the involvement of superoxide radicals (O2*-) and hydrogen peroxide in the denitration process. Results obtained in this study reveal for the first time that extracellular small-molecular-weight substance(s) of bacterial origin can serve as green catalyst(s) to initiate TNT denitration. In addition, this study gives clear evidence for the production of a TNT metabolite bearing a single nitro groupfollowing a denitration reaction with catalyst(s) of biotic origin.

Characterization of secondary organic aerosol from photo-oxidation of gasoline exhaust and specific sources of major components.

PubMed

Ma, Pengkun; Zhang, Peng; Shu, Jinian; Yang, Bo; Zhang, Haixu

2018-01-01

To further explore the composition and distribution of secondary organic aerosol (SOA) components from the photo-oxidation of light aromatic precursors (toluene, m-xylene, and 1,3,5-trimethylbenzene (1,3,5-TMB)) and idling gasoline exhaust, a vacuum ultraviolet photoionization mass spectrometer (VUV-PIMS) was employed. Peaks of the molecular ions of the SOA components with minimum molecular fragmentation were clearly observed from the mass spectra of SOA, through the application of soft ionization methods in VUV-PIMS. The experiments comparing the exhaust-SOA and light aromatic mixture-SOA showed that the observed distributions of almost all the predominant cluster ions in the exhaust-SOA were similar to that of the mixture-SOA. Based on the characterization experiments of SOA formed from individual light aromatic precursors, the SOA components with molecular weights of 98 and 110 amu observed in the exhaust-SOA resulted from the photo-oxidation of toluene and m-xylene; the components with a molecular weight of 124 amu were derived mainly from m-xylene; and the components with molecular weights of 100, 112, 128, 138, and 156 amu were mainly derived from 1,3,5-TMB. These results suggest that C 7 -C 9 light aromatic hydrocarbons are significant SOA precursors and that major SOA components originate from gasoline exhaust. Additionally, some new light aromatic hydrocarbon-SOA components were observed for the first time using VUV-PIMS. The corresponding reaction mechanisms were also proposed in this study to enrich the knowledge base of the formation mechanisms of light aromatic hydrocarbon-SOA compounds. Copyright © 2017 Elsevier Ltd. All rights reserved.

Catalytic conversion of biomass pyrolysis-derived compounds with chemical liquid deposition (CLD) modified ZSM-5.

PubMed

Zhang, Huiyan; Luo, Mengmeng; Xiao, Rui; Shao, Shanshan; Jin, Baosheng; Xiao, Guomin; Zhao, Ming; Liang, Junyu

2014-03-01

Chemical liquid deposition (CLD) with KH550, TEOS and methyl silicone oil as the modifiers was used to modify ZSM-5 and deposit its external acid sites. The characteristics of modified catalysts were tested by catalytic conversion of biomass pyrolysis-derived compounds. The effects of different modifying conditions (deposited amount, temperature, and time) on the product yields and selectivities were investigated. The results show KH550 modified ZSM-5 (deposited amount of 4%, temperature of 20°C and time of 6h) produced the maximum yields of aromatics (24.5%) and olefins (16.5%), which are much higher than that obtained with original ZSM-5 catalyst (18.8% aromatics and 9.8% olefins). The coke yield decreased from 44.1% with original ZSM-5 to 26.7% with KH550 modified ZSM-5. The selectivities of low-molecule-weight hydrocarbons (ethylene and benzene) decreased, while that of higher molecule-weight hydrocarbons (propylene, butylene, toluene, and naphthalene) increased comparing with original ZSM-5. Copyright © 2013 Elsevier Ltd. All rights reserved.

Effects of vehicle type and fuel quality on real world toxic emissions from diesel vehicles

NASA Astrophysics Data System (ADS)

Nelson, Peter F.; Tibbett, Anne R.; Day, Stuart J.

Diesel vehicles are an important source of emissions of air pollutants, particularly oxides of nitrogen (NO x), particulate matter (PM), and toxic compounds with potential health impacts including volatile organic compounds (VOCs) such as benzene and aldehydes, and polycyclic aromatic hydrocarbons (PAHs). Current developments in engine design and fuel quality are expected to reduce these emissions in the future, but many vehicles exceed 10 years of age and may make a major contribution to urban pollutant concentrations and related health impacts for many years. In this study, emissions of a range of toxic compounds are reported using in-service vehicles which were tested using urban driving cycles developed for Australian conditions. Twelve vehicles were chosen from six vehicle weight classes and, in addition, two of these vehicles were driven through the urban drive cycle using a range of diesel fuel formulations. The fuels ranged in sulphur content from 24 to 1700 ppm, and in total aromatics from 7.7 to 33 mass%. Effects of vehicle type and fuel composition on emissions are reported. The results show that emissions of these toxic species were broadly comparable to those observed in previous dynamometer and tunnel studies. Emissions of VOCs and smaller PAHs such as naphthalene, which are derived largely from the combustion process, appear to be related, and show relatively little variability when compared with the variability in emissions of aldehydes and larger PAHs. In particular, aldehyde emissions are highly variable and may be related to engine operating conditions. Fuels of lower sulphur and aromatic content did not have a significant influence on emissions of VOCs and aldehydes, but tended to result in lower emissions of PAHs. The toxicity of vehicle exhaust, as determined by inhalation risk and toxic equivalency factor (TEF)-weighted PAH emissions, was reduced with fuels of lower aromatic content.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Howard, J. B.; Richter, H.

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

Polyimides containing pendent trifluoromethyl groups

NASA Technical Reports Server (NTRS)

Havens, S. J.; Hergenrother, P. M.

1993-01-01

Several new polyimides containing trifluoromethyl groups were prepared from the reaction of various aromatic dianhydrides and two new diamines containing trifluoromethyl groups, 4,4'-bis(3-amino-5-trifluoromethylphenoxy)biphenyl and l,4-bis(3-amino-5-trifluoromethylphenoxy)benzene. The diamines were prepared from the aromatic nucleophilic displacement of the disodium salts of 4,4'-biphenol or hydroquinone with 3,5-dinitrobenzotrifluoride followed by hydrogenation of the resultant dinitro compounds. The thermally cured polyimides exhibited glass transition temperatures between 186 and 262 C. By thermogravimetric analysis, the polyimides exhibited 5 percent weight losses at 484-527 C in nitrogen and 452-506 C in air.

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.

Fluorescent characteristics of estrogenic compounds in landfill leachate.

PubMed

Zhanga, Hua; Changb, Cheng-Hsuan; Lü, Fan; Su, Ay; Lee, Duu-Jong; He, Pin-Jing; Shao, Li-Ming

2009-08-01

Estrogens in landfill leachate could probably contaminate receiving water sources if not properly polished before discharge. This work measured, using an estrogen receptor-alpha competitor screening assay, the estrogenic potentials of leachate samples collected at a local sanitary landfill in Shanghai, China and their compounds fractionated by molecular weights. The chemical structures of the constituent compounds were characterized using fluorescence excitation and emission matrix (EEM). The organic matters of molecular weight <600 Da and of 3000-14,000 Da contributed most of the estrogenic potentials of the raw leachates. The former were considered as the typical endocrine disrupting compounds in dissolved state; while the latter the fulvic acids with high aromaticity that were readily adsorbed with estrogens (bound state). Statistical analysis on EEM peaks revealed that the chemical structures of noted estrogens in dissolved state and in bound state were not identical. Aerobic treatment effectively removed dissolved estrogens, but rarely removed those bound estrogens.

Ground-water contamination at an inactive coal and oil gasification plant site, Gas Works Park, Seattle, Washington

USGS Publications Warehouse

Turney, G.L.; Goerlitz, D.F.

1989-01-01

Gas Works Park, in Seattle, Washington, is located on the site of a coal and oil gasification plant that ceased operation in 1956. During operation, many types of wastes, including coal, tar, and oil, accumulated on site. The park soil is presently (1986) contaminated with compounds such as polynuclear aromatic hydrocarbons, volatile organic compounds, trace metals, and cyanide. Analyses of water samples from a network of observation wells in the park indicate that these compounds are also present in the groundwater. Polynuclear aromatic hydrocarbons and volatile organic compounds were identified in groundwater samples in concentrations as large as 200 mg/L. Concentrations of organic compounds were largest where groundwater was in contact with a nonaqueous phase liquid in the soil. Concentrations in groundwater were much smaller where no nonaqueous phase liquid was present, even if the groundwater was in contact with contaminated soils. This condition is attributed to weathering processes at the site, such as dissolution, volatilization, and biodegradation. Soluble, volatile, low-molecular-weight organic compounds are preferentially dissolved from the nonaqueous phase liquid into the groundwater. Where no nonaqueous phase liquid is present, only stained soils containing relatively insoluble, high-molecular-weight compounds remain; therefore, contaminant concentrations in the groundwater are much smaller. Concentrations of organic contaminants in the soils may still remain large. Values of specific conductance were as large as 5,280 microsiemens/cm, well above a background of 242 microsiemens/cm, suggesting large concentrations of minerals in the groundwater. Trace metal concentrations, however , were generally < 0.010 mg/L, and below limits of US EPA drinking water standards. Cyanide was present in groundwater samples from throughout the park, ranging in concentration from 0.01 to 8.6 mg/L. (Author 's abstract)

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

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.

Biotechnological production of aromatic compounds of the extended shikimate pathway from renewable biomass.

PubMed

Lee, Jin-Ho; Wendisch, Volker F

2017-09-10

Aromatic chemicals that contain an unsaturated ring with alternating double and single bonds find numerous applications in a wide range of industries, e.g. paper and dye manufacture, as fuel additives, electrical insulation, resins, pharmaceuticals, agrochemicals, in food, feed and cosmetics. Their chemical production is based on petroleum (BTX; benzene, toluene, and xylene), but they can also be obtained from plants by extraction. Due to petroleum depletion, health compliance, or environmental issues such as global warming, the biotechnological production of aromatics from renewable biomass came more and more into focus. Lignin, a complex polymeric aromatic molecule itself, is a natural source of aromatic compounds. Many microorganisms are able to catabolize a plethora of aromatic compounds and interception of these pathways may lead to the biotechnological production of value-added aromatic compounds which will be discussed for Corynebacterium glutamicum. Biosynthesis of aromatic amino acids not only gives rise to l-tryptophan, L-tyrosine and l-phenylalanine, but also to aromatic intermediates such as dehydroshikimate or chorismate from which value-added aromatic compounds can be derived. In this review, we will summarize recent strategies for the biotechnological production of aromatic and related compounds from renewable biomass by Escherichia coli, Pseudomonas putida, C. glutamicum and Saccharomyces cerevisiae. In particular, we will focus on metabolic engineering of the extended shikimate pathway. Copyright © 2016 Elsevier B.V. All rights reserved.

PERFLUORINATED AROMATIC COMPOUND

DTIC Science & Technology

octafluorobiphenyl, and perfluoroaliphatic aldehydes. Synthetic routes to perfluoro cyclohexyls via reactions of phenyl and pentafluorphenyl lithium with...other perfluorinated aromatic compounds were employed in the synthesis of perfluorinated aromatic model compounds and polymers. The hydrogenic analogues...hydrazides, and imides. Synthetic routes to perfluoro aralkyl compounds are being investigated. Starting materials are tetrafluorobenzene

Suspended particulate matter collection methods influence the quantification of polycyclic aromatic compounds in the river system.

PubMed

Abuhelou, Fayez; Mansuy-Huault, Laurence; Lorgeoux, Catherine; Catteloin, Delphine; Collin, Valéry; Bauer, Allan; Kanbar, Hussein Jaafar; Gley, Renaud; Manceau, Luc; Thomas, Fabien; Montargès-Pelletier, Emmanuelle

2017-10-01

In this study, we compared the influence of two different collection methods, filtration (FT) and continuous flow field centrifugation (CFC), on the concentration and the distribution of polycyclic aromatic compounds (PACs) in suspended particulate matter (SPM) occurring in river waters. SPM samples were collected simultaneously with FT and CFC from a river during six sampling campaigns over 2 years, covering different hydrological contexts. SPM samples were analyzed to determine the concentration of PACs including 16 polycyclic aromatic hydrocarbons (PAHs), 11 oxygenated PACs (O-PACs), and 5 nitrogen PACs (N-PACs). Results showed significant differences between the two separation methods. In half of the sampling campaigns, PAC concentrations differed from a factor 2 to 30 comparing FT and CFC-collected SPMs. The PAC distributions were also affected by the separation method. FT-collected SPM were enriched in 2-3 ring PACs whereas CFC-collected SPM had PAC distributions dominated by medium to high molecular weight compounds typical of combustion processes. This could be explained by distinct cut-off threshold of the two separation methods and strongly suggested the retention of colloidal and/or fine matter on glass-fiber filters particularly enriched in low molecular PACs. These differences between FT and CFC were not systematic but rather enhanced by high water flow rates.

Catalytic conversion of lignin pyrolysis model compound- guaiacol and its kinetic model including coke formation.

PubMed

Zhang, Huiyan; Wang, Yun; Shao, Shanshan; Xiao, Rui

2016-11-21

Lignin is the most difficult to be converted and most easy coking component in biomass catalytic pyrolysis to high-value liquid fuels and chemicals. Catalytic conversion of guaiacol as a lignin model compound was conducted in a fixed-bed reactor over ZSM-5 to investigate its conversion and coking behaviors. The effects of temperature, weight hourly space velocity (WHSV) and partial pressure on product distribution were studied. The results show the maximum aromatic carbon yield of 28.55% was obtained at temperature of 650 °C, WHSV of 8 h -1 and partial pressure of 2.38 kPa, while the coke carbon yield was 19.55%. The reaction pathway was speculated to be removing methoxy group to form phenols with further aromatization to form aromatics. The amount of coke increased with increasing reaction time. The surface area and acidity of catalysts declined as coke formed on the acid sites and blocked the pore channels, which led to the decrease of aromatic yields. Finally, a kinetic model of guaiacol catalytic conversion considering coke deposition was built based on the above reaction pathway to properly predict product distribution. The experimental and model predicting data agreed well. The correlation coefficient of all equations were all higher than 0.90.

Catalytic conversion of lignin pyrolysis model compound- guaiacol and its kinetic model including coke formation

PubMed Central

Zhang, Huiyan; Wang, Yun; Shao, Shanshan; Xiao, Rui

2016-01-01

Lignin is the most difficult to be converted and most easy coking component in biomass catalytic pyrolysis to high-value liquid fuels and chemicals. Catalytic conversion of guaiacol as a lignin model compound was conducted in a fixed-bed reactor over ZSM-5 to investigate its conversion and coking behaviors. The effects of temperature, weight hourly space velocity (WHSV) and partial pressure on product distribution were studied. The results show the maximum aromatic carbon yield of 28.55% was obtained at temperature of 650 °C, WHSV of 8 h−1 and partial pressure of 2.38 kPa, while the coke carbon yield was 19.55%. The reaction pathway was speculated to be removing methoxy group to form phenols with further aromatization to form aromatics. The amount of coke increased with increasing reaction time. The surface area and acidity of catalysts declined as coke formed on the acid sites and blocked the pore channels, which led to the decrease of aromatic yields. Finally, a kinetic model of guaiacol catalytic conversion considering coke deposition was built based on the above reaction pathway to properly predict product distribution. The experimental and model predicting data agreed well. The correlation coefficient of all equations were all higher than 0.90. PMID:27869228

Linear solvation energy relationships (LSER) for adsorption of organic compounds by carbon nanotubes.

PubMed

Ersan, Gamze; Apul, Onur G; Karanfil, Tanju

2016-07-01

The objective of this paper was to create a comprehensive database for the adsorption of organic compounds by carbon nanotubes (CNTs) and to use the Linear Solvation Energy Relationship (LSER) technique for developing predictive adsorption models of organic compounds (OCs) by multi-walled carbon nanotubes (MWCNTs) and single-walled carbon nanotubes (SWCNTs). Adsorption data for 123 OCs by MWCNTs and 48 OCs by SWCNTs were compiled from the literature, including some experimental results obtained in our laboratory. The roles of selected OCs properties and CNT types were examined with LSER models. The results showed that the r(2) values of the LSER models displayed small variability for aromatic compounds smaller than 220 g/mol, after which a decreasing trend was observed. The data available for aliphatics was mainly for molecular weights smaller than 250 g/mol, which showed a similar trend to that of aromatics. The r(2) values for the LSER model on the adsorption of aromatic and aliphatic OCs by SWCNTs and MWCNTs were relatively similar indicating the linearity of LSER models did not depend on the CNT types. Among all LSER model descriptors, V term (molecular volume) for aromatic OCs and B term (basicity) for aliphatic OCs were the most predominant descriptors on both type of CNTs. The presence of R term (excess molar refractivity) in LSER model equations resulted in decreases for both V and P (polarizability) parameters without affecting the r(2) values. Overall, the results demonstrate that successful predictive models can be developed for the adsorption of OCs by MWCNTs and SWCNTs with LSER techniques. Copyright © 2016 Elsevier Ltd. All rights reserved.

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.

Effects of halogenated aromatics/aliphatics and nitrogen(N)-heterocyclic aromatics on estimating the persistence of future pharmaceutical compounds using a modified QSAR model.

PubMed

Lim, Seung Joo; Fox, Peter

2014-02-01

The effects of halogenated aromatics/aliphatics and nitrogen(N)-heterocyclic aromatics on estimating the persistence of future pharmaceutical compounds were investigated using a modified half life equation. The potential future pharmaceutical compounds investigated were approximately 2000 pharmaceutical drugs currently undergoing the United States Food and Drug Administration (US FDA) testing. EPI Suite (BIOWIN) model estimates the fates of compounds based on the biodegradability under aerobic conditions. While BIOWIN considered the biodegradability of a compound only, the half life equation used in this study was modified by biodegradability, sorption and cometabolic oxidation. It was possible that the potential future pharmaceutical compounds were more accurately estimated using the modified half life equation. The modified half life equation considered sorption and cometabolic oxidation of halogenated aromatic/aliphatics and nitrogen(N)-heterocyclic aromatics in the sub-surface, while EPI Suite (BIOWIN) did not. Halogenated aliphatics in chemicals were more persistent than halogenated aromatics in the sub-surface. In addition, in the sub-surface environment, the fates of organic chemicals were much more affected by halogenation in chemicals than by nitrogen(N)-heterocyclic aromatics. © 2013.

Insight into unresolved complex mixtures of aromatic hydrocarbons in heavy oil via two-dimensional gas chromatography coupled with time-of-flight mass spectrometry analysis.

PubMed

Weng, Na; Wan, Shan; Wang, Huitong; Zhang, Shuichang; Zhu, Guangyou; Liu, Jingfu; Cai, Di; Yang, Yunxu

2015-06-12

The aromatic hydrocarbon fractions of five crude oils representing a natural sequence of increasing degree of biodegradation from the Liaohe Basin, NE, China, were analyzed using conventional gas chromatography-mass spectrometry (GC-MS) and comprehensive two-dimensional gas chromatography (GC×GC). Because of the limited peak capability and low resolution, compounds in the aromatic fraction of a heavily biodegraded crude oil that were analyzed by GC-MS appeared as unresolved complex mixtures (UCMs) or GC "humps". They could be separated based on their polarity by GC×GC. UCMs are composed mainly of aromatic biomarkers and aromatic hydrocarbons with branched alkanes or cycloalkanes substituents. The quantitative results achieved by GC×GC-FID were shown that monoaromatic hydrocarbons account for the largest number and mass of UCMs in the aromatic hydrocarbon fraction of heavily biodegraded crude oil, at 45% by mass. The number and mass of diaromatic hydrocarbons ranks second at 33% by mass, followed by the aromatic biomarker compounds, triaromatic, tetraaromatic, and pentaaromatic hydrocarbons, that account for 10%, 6%, 1.5%, and 0.01% of all aromatic compounds by mass, respectively. In the heavily biodegraded oil, compounds with monocyclic cycloalkane substituents account for the largest proportion of mono- and diaromatic hydrocarbons, respectively. The C4-substituted compounds account for the largest proportion of naphthalenes and the C3-substituted compounds account for the largest proportion of phenanthrenes, which is very different from non-biodegraded, slightly biodegraded, and moderately biodegraded crude oil. It is inferred that compounds of monoaromatic, diaromatic and triaromatic hydrocarbons are affected by biodegradation, that compounds with C1-, C2-substituents are affected by the increase in degree of biodegradation, and that their relative content decreased, whereas compounds with C3-substituents or more were affected slightly or unaffected, and their relative content also increased. The varying regularity of relative content of substituted compounds may be used to reflect the degree of degradation of heavy oil. Moreover, biomarkers for the aromatic hydrocarbons of heavily biodegraded crude oil are mainly aromatic steranes, aromatic secohopanes, aromatic pentacyclotriterpanes, and benzohopanes. According to resultant data, aromatic secohopanes could be used as a specific marker because of their relatively high concentration. This aromatic compound analysis of a series of biodegraded crude oil is useful for future research on the quantitative characterization of the degree of biodegradation of heavy oil, unconventional oil maturity evaluation, oil source correlation, depositional environment, and any other geochemical problems. Copyright © 2015 Elsevier B.V. All rights reserved.

Investigation of colloidal graphite as a matrix for matrix-assisted laser desorption/ionisation mass spectrometry of low molecular weight analytes.

PubMed

Warren, Alexander D; Conway, Ulric; Arthur, Christopher J; Gates, Paul J

2016-07-01

The analysis of low molecular weight compounds by matrix-assisted laser desorption/ionisation mass spectrometry is problematic due to the interference and suppression of analyte ionisation by the matrices typically employed - which are themselves low molecular weight compounds. The application of colloidal graphite is demonstrated here as an easy to use matrix that can promote the ionisation of a wide range of analytes including low molecular weight organic compounds, complex natural products and inorganic complexes. Analyte ionisation with colloidal graphite is compared with traditional organic matrices along with various other sources of graphite (e.g. graphite rods and charcoal pencils). Factors such as ease of application, spectra reproducibility, spot longevity, spot-to-spot reproducibility and spot homogeneity (through single spot imaging) are explored. For some analytes, considerable matrix suppression effects are observed resulting in spectra completely devoid of matrix ions. We also report the observation of radical molecular ions [M(-●) ] in the negative ion mode, particularly with some aromatic analytes. Copyright © 2016 John Wiley & Sons, Ltd. Copyright © 2016 John Wiley & Sons, Ltd.

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

Chemistry and properties of new poly(arylene ether imidazoles)

NASA Technical Reports Server (NTRS)

Connell, J. W.; Hergenrother, P. M.

1990-01-01

As part of a program to develop high-temperature high-performance structural resins for aerospace applications, the chemistry and properties of new poly(arylene ether imidazoles) were investigated. The polymers were prepared by the nucleophilic displacement reaction of aromatic bis(imidazolephenols) with activated aromatic difluoro compounds. The amorphous thermoplastic polymers exhibited glass transition temperatures from 230 to 301 C, inherent viscosities from 0.46 to 1.46 dL/g, and number-average molecular weights as high as 59,300 g/mole. The polymers exhibit good toughness, adhesive, composite, and film properties. The chemical, physical, and mechanical properties of these materials are discussed.

Response of humic acid formation to elevated nitrate during chicken manure composting.

PubMed

Shi, Mingzi; Wei, Zimin; Wang, Liqin; Wu, Junqiu; Zhang, Duoying; Wei, Dan; Tang, Yu; Zhao, Yue

2018-06-01

Nitrate can stimulate microbes to degrade aromatic compounds, whereas humic acid (HA) as a high molecular weight aromatic compound, its formation may be affected by elevated nitrate during composting. Therefore, this study is conducted to determine the effect of elevated nitrate on HA formation. Five tests were executed by adding different nitrate concentrations to chicken manure composting. Results demonstrate that the concentration of HA in treatment group is significantly decreased compared with control group (p < 0.05), especially in the highest nitrate concentration group. RDA indicates that the microbes associated with HA and environmental parameters are influenced by elevated nitrate. Furthermore, structural equation model reveals that elevated nitrate reduces HA formation by mediating microbes directly, or by affecting ammonia and pH as the indirect drivers to regulate microbial community structure. Copyright © 2018 Elsevier Ltd. All rights reserved.

Essential oil composition of stems and fruits of Caralluma europaea N.E.Br. (Apocynaceae).

PubMed

Zito, Pietro; Sajeva, Maurizio; Bruno, Maurizio; Maggio, Antonella; Rosselli, Sergio; Formisano, Carmen; Senatore, Felice

2010-01-27

The essential oil of the stems and fruits of Caralluma europaea (Guss.) N.E.Br. (Apocynaceae) from Lampedusa Island has been obtained by hydrodistillation and its composition analyzed. The analyses allowed the identification and quantification of 74 volatile compounds, of which 16 were aromatic and 58 non-aromatic. Stems and fruits contained 1.4% and 2.7% of aromatic compounds respectively, while non-aromatic were 88.3% and 88.8%. Non-aromatic hydrocarbons were the most abundant compounds in both organs, followed by fatty acids. Data showed differences in the profiles between stems and fruits which shared only eighteen compounds; stems accounted for 38 compounds while fruits for 53. Fruits showed a higher diversity especially in aromatic compounds with twelve versus four in stems. Among the volatiles identified in stems and fruits of C. europaea 26 are present in other taxa of Apocynaceae, 52 are semiochemicals for many insects, and 21 have antimicrobial activity. The possible ecological role of the volatiles found is briefly discussed.

CYP63A2, a catalytically versatile fungal P450 monooxygenase capable of oxidizing higher-molecular-weight polycyclic aromatic hydrocarbons, alkylphenols, and alkanes

EPA Science Inventory

Cytochrome P450 monooxygenases (P450s) are known to oxidize hydrocarbons albeit with limited substrate specificity across classes of these compounds. Here we report a P450 monooxygenase (CYP63A2) from the model ligninolytic white rot fungus Phanerochaete chrysosporium that was fo...

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

Contamination of agricultural lands by polycyclic aromatic hydrocarbons (Tver region, Russia)

NASA Astrophysics Data System (ADS)

Zhidkin, Andrey; Koshovskii, Timur; Gennadiev, Alexander

2016-04-01

It is important to study sources and concentrations of polycyclic aromatic hydrocarbons (PAHs) in the agriculture soils within areas without intensive contaminations. Our studied object was soil and snow cover in the taiga zone (Tver region, Russia). A total of 52 surface (0-30 cm) and 31 subsurface (30-50 cm) soil samples, and 13 snow samples were collected in 35 soil pits, located in forest, crop and layland soils. Studied concentrations of the following 11 individual compounds: two-ring compounds (diphenyl and naphthalene homologues); three-ring compounds (fluorene, phenanthrene, anthracene); four-ring compounds (chrysene, pyrene, tetraphene); five-ring compounds (perylene, benzo[a]pyrene); and six-ring compounds (benzo[ghi]perylene). Analyses made by specrtofluorometry method at the temperature of liquid nitrogen. The total concentrations of all PAHs in soil samples ranged from 9 to 770 ng*g-1 with a median of 96 ng*g-1. The sum of high molecular weight PAHs was significantly lower than the sum of low molecular weight PAHs in the studied soils. The phenanthrene concentration was highest and ranged from 1.2 to 720 ng*g-1 (medium 72 ng*g-1). Compared PAHs reserves in snow cover (μg*m-2) with the reserves in topsoil layer (μg*m-2 in the upper 30 cm). Low molecular weight PAHs (fluorene, phenanthrene, diphenyl, naphthalene) reserves in snow was less than 20% from the reserves in the soil surface layer. High molecular weight PAHs (benzo[a]pyrene, chrysene, perylene, pyrene and tetraphene) reserves in snow was about 50-70% from the reserves in soil surface layer. High molecular weight PAHs (benzo[ghi]perylene and anthracene) reserves in snow was more than in topsoil. PAHs vertical distribution in soil profiles was statistically examined. The total concentration of all PAHs decreased with depth in all studied forest soils. In the arable soils was no significant trend in domination of PAHs total concentrations in the plowing and subsoil layers. The ratio of topsoil to subsoil concentrations of PAHs is different for differ congeners. Contents of phenanthrene and fluorene predominantly increase with the depth. Content of high molecular weight PAHs (benzo[a]pyrene, anthracene, tetraphene, perylene and pyrene) predominantly decreased with the depth. Other PAHs congeners have indistinct profile distributions in studied pits. Based on studied results PAHs divided to associations with different concentrations, sources and vertical distribution in soils: a) phenanthrene and fluorine; b) naphthalene, diphenyl; c) pyrene, benzo(a)pyrene, tetraphene, perylene, chrysene; d) anthracene and benzo(ghi)perylene. Research is funded by Russian Science Foundation (Project 14-27-00083).

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 between LMW and HMW PAHs for most of the streams and between historical-use organochlorine compounds and total organic carbon and clay content of sediments for one of the streams (Brush Creek). Stormwater runoff transport modes are proposed to describe how the two groups of contaminants migrated and distributed in the streambed. ?? 2010 Springer Science+Business Media, LLC.

Subcritical water extraction of organic matter from sedimentary rocks.

PubMed

Luong, Duy; Sephton, Mark A; Watson, Jonathan S

2015-06-16

Subcritical water extraction of organic matter containing sedimentary rocks at 300°C and 1500 psi produces extracts comparable to conventional solvent extraction. Subcritical water extraction of previously solvent extracted samples confirms that high molecular weight organic matter (kerogen) degradation is not occurring and that only low molecular weight organic matter (free compounds) are being accessed in analogy to solvent extraction procedures. The sedimentary rocks chosen for extraction span the classic geochemical organic matter types. A type I organic matter-containing sedimentary rock produces n-alkanes and isoprenoidal hydrocarbons at 300°C and 1500 psi that indicate an algal source for the organic matter. Extraction of a rock containing type II organic matter at the same temperature and pressure produces aliphatic hydrocarbons but also aromatic compounds reflecting the increased contributions from terrestrial organic matter in this sample. A type III organic matter-containing sample produces a range of non-polar and polar compounds including polycyclic aromatic hydrocarbons and oxygenated aromatic compounds at 300°C and 1500 psi reflecting a dominantly terrestrial origin for the organic materials. Although extraction at 300°C and 1500 psi produces extracts that are comparable to solvent extraction, lower temperature steps display differences related to organic solubility. The type I organic matter produces no products below 300°C and 1500 psi, reflecting its dominantly aliphatic character, while type II and type III organic matter contribute some polar components to the lower temperature steps, reflecting the chemical heterogeneity of their organic inventory. The separation of polar and non-polar organic compounds by using different temperatures provides the potential for selective extraction that may obviate the need for subsequent preparative chromatography steps. Our results indicate that subcritical water extraction can act as a suitable replacement for conventional solvent extraction of sedimentary rocks, but can also be used for any organic matter containing mineral matrix, including soils and recent sediments, and has the added benefit of tailored extraction for analytes of specific polarities. Copyright © 2015 The Authors. Published by Elsevier B.V. All rights reserved.

Small-scale hydrous pyrolysis of macromolecular material in meteorites

NASA Astrophysics Data System (ADS)

Sephton, M. A.; Pillinger, C. T.; Gilmour, I.

1998-12-01

The hydrous pyrolysis method, usually performed on several hundred grams of terrestrial rock sample, has been scaled down to accommodate less than two grams of meteorite sample. This technique makes full use of the high yields associated with hydrous pyrolysis experiments and permits the investigation of the meteorite macromolecular material, the major organic component in carbonaceous meteorites. The hydrous pyrolysis procedure transforms the high molecular weight macromolecular material into low molecular weight fragments. The released entities can then be extracted with supercritical fluid extraction. In contrast to the parent structure, the pyrolysis products are amenable for analysis by gas chromatography-based techniques. When subjected to hydrous pyrolysis, two carbonaceous chondrites (Orgueil and Cold Bokkeveld) released generally similar products, which consisted of abundant volatile aromatic and alkyl-substituted aromatic compounds. These results revealed the ability of small-scale hydrous pyrolysis to dissect extraterrestrial macromolecular material and thereby reveal its organic constitution.

Di(hydroxyphenyl)- 1,2,4-triazole monomers

NASA Technical Reports Server (NTRS)

Connell, John W. (Inventor); Hergenrother, Paul M. (Inventor); Wolf, Peter (Inventor)

1993-01-01

The di(hydroxyphenyl)- 1,2,4-triazole monomers were first synthesized by reacting bis (4-hydroxyphenyl) hydrazide with aniline hydrochloride at 250 C in the melt and also by reacting 1,3 or 1,4-bis- (4-hydroxyphenyl)- phenylene- dihydrazide with 2 moles of aniline hydrochloride in the melt. Purification of the di(hydroxyphenyl)- 1,2,4-triazole monomers was accomplished by recrystallization. Poly (1,2,4-triazoles) (PT) were prepared by the aromatic nucleophilic displacement reaction of di(hydroxyphenyl)- 1,2,4-triazole monomers with activated aromatic dihalides or activated aromatic dinitro compounds. The reactions were carried out in polar aprotic solvents such as sulfolane or diphenylsulfone using alkali metal bases such as potassium carbonate at elevated temperatures under nitrogen. This synthetic route has provided high molecular weight PT 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.

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.

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.

Mathematical modeling of atmospheric fine particle-associated primary organic compound concentrations

NASA Astrophysics Data System (ADS)

Rogge, Wolfgang F.; Hildemann, Lynn M.; Mazurek, Monica A.; Cass, Glen R.; Simoneit, Bernd R. T.

1996-08-01

An atmospheric transport model has been used to explore the relationship between source emissions and ambient air quality for individual particle phase organic compounds present in primary aerosol source emissions. An inventory of fine particulate organic compound emissions was assembled for the Los Angeles area in the year 1982. Sources characterized included noncatalyst- and catalyst-equipped autos, diesel trucks, paved road dust, tire wear, brake lining dust, meat cooking operations, industrial oil-fired boilers, roofing tar pots, natural gas combustion in residential homes, cigarette smoke, fireplaces burning oak and pine wood, and plant leaf abrasion products. These primary fine particle source emissions were supplied to a computer-based model that simulates atmospheric transport, dispersion, and dry deposition based on the time series of hourly wind observations and mixing depths. Monthly average fine particle organic compound concentrations that would prevail if the primary organic aerosol were transported without chemical reaction were computed for more than 100 organic compounds within an 80 km × 80 km modeling area centered over Los Angeles. The monthly average compound concentrations predicted by the transport model were compared to atmospheric measurements made at monitoring sites within the study area during 1982. The predicted seasonal variation and absolute values of the concentrations of the more stable compounds are found to be in reasonable agreement with the ambient observations. While model predictions for the higher molecular weight polycyclic aromatic hydrocarbons (PAH) are in agreement with ambient observations, lower molecular weight PAH show much higher predicted than measured atmospheric concentrations in the particle phase, indicating atmospheric decay by chemical reactions or evaporation from the particle phase. The atmospheric concentrations of dicarboxylic acids and aromatic polycarboxylic acids greatly exceed the contributions that are due to direct emissions from primary sources, confirming that these compounds are principally formed by atmospheric chemical reactions.

Photochemical processes on Titan: Irradiation of mixtures of gases that simulate Titan's atmosphere

NASA Astrophysics Data System (ADS)

Tran, Buu N.; Joseph, Jeffrey C.; Force, Michael; Briggs, Robert G.; Vuitton, Veronique; Ferris, James P.

2005-09-01

Photochemical reaction pathways in Titan's atmosphere were investigated by irradiation of the individual components and the mixture containing nitrogen, methane, hydrogen, acetylene, ethylene, and cyanoacetylene. The quantum yields for the loss of the reactants and the formation of products were determined. Photolysis of ethylene yields mainly saturated compounds (ethane, propane, and butane) while photolysis of acetylene yields the same saturated compounds as well as ethylene and diacetylene. Irradiation of cyanoacetylene yields mainly hydrogen cyanide and small amounts of acetonitrile. When an amount of methane corresponding to its mixing ratio on Titan was added to these mixtures the quantum yields for the loss of reactants decreased and the quantum yields for hydrocarbon formation increased indicative of a hydrogen atom abstraction from methane by the photochemically generated radicals. GC/MS analysis of the products formed by irradiation of mixtures of all these gases generated over 120 compounds which were mainly aliphatic hydrocarbons containing double and triple bonds along with much smaller amounts of aromatic compounds like benzene, toluene and phenylacetylene. The reaction pathways were investigated by the use of 13C acetylene in these gas mixtures. No polycyclic aromatic compounds were detected. Vapor pressures of these compounds under conditions present in Titan's atmosphere were calculated. The low molecular weight compounds likely to be present in the atmosphere and aerosols of Titan as a result of photochemical processes are proposed.

Oxidation of aromatic contaminants coupled to microbial iron reduction

USGS Publications Warehouse

Lovley, D.R.; Baedecker, M.J.; Lonergan, D.J.; Cozzarelli, I.M.; Phillips, E.J.P.; Siegel, D.I.

1989-01-01

THE contamination of sub-surface water supplies with aromatic compounds is a significant environmental concern1,2. As these contaminated sub-surface environments are generally anaerobic, the microbial oxidation of aromatic compounds coupled to nitrate reduction, sulphate reduction and methane production has been studied intensively1-7. In addition, geochemical evidence suggests that Fe(III) can be an important electron acceptor for the oxidation of aromatic compounds in anaerobic groundwater. Until now, only abiological mechanisms for the oxidation of aromatic compounds with Fe(III) have been reported8-12. Here we show that in aquatic sediments, microbial activity is necessary for the oxidation of model aromatic compounds coupled to Fe(III) reduction. Furthermore, a pure culture of the Fe(III)-reducing bacterium GS-15 can obtain energy for growth by oxidizing benzoate, toluene, phenol or p-cresol with Fe(III) as the sole electron acceptor. These results extend the known physiological capabilities of Fe(III)-reducing organisms and provide the first example of an organism of any type which can oxidize an aromatic hydrocarbon anaerobically. ?? 1989 Nature Publishing Group.

Hydrocarbons in surface sediments from the Sfax coastal zone, (Tunisia) Mediterranean Sea.

PubMed

Zaghden, Hatem; Kallel, Monem; Louati, Afifa; Elleuch, Boubaker; Oudot, Jean; Saliot, Alain

2005-11-01

The Semi-enclosed Mediterranean Sea records various signals of high anthropic pressures from surrounding countries and the industrialized European countries. This is particularly true for oil pollution. Although accounting for 1% of the world's ocean surface, it receives about 25% of the petroleum inputs to the ocean. To achieve a global budget we need to collect information from different parts of the Mediterranean. Particularly, we focus in this paper on the Southern Mediterranean, where data are presently very scarce. In this context, the University of Sfax has undertaken an estimation of hydrocarbon pollution along the coasts of Sfax and Gabès Gulf. Non-aromatic hydrocarbons were analysed in 8 surface sediments by FT/IR and GC/MS. Non-aromatic hydrocarbon concentrations vary in the range 310-1406 microg g(-1) sediments dry weight, which is high, compared to other Mediterranean sites. GC/MS data indicate a large group of unresolved compounds suggesting a petroleum contamination, confirmed by the identification of hopanes with predominant C29 and C30alpha,beta compounds and steranes with predominance of C27 over C28) and C29 compounds.

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.

Bioremediation of PAH-contamined soils: Consequences on formation and degradation of polar-polycyclic aromatic compounds and microbial community abundance.

PubMed

Biache, Coralie; Ouali, Salma; Cébron, Aurélie; Lorgeoux, Catherine; Colombano, Stéfan; Faure, Pierre

2017-05-05

A bioslurry batch experiment was carried out over five months on three polycyclic aromatic compound (PAC) contaminated soils to study the PAC (PAH and polar-PAC) behavior during soil incubation and to evaluate the impact of PAC contamination on the abundance of microbial communities and functional PAH-degrading populations. Organic matter characteristics and reactivity, assessed through solvent extractable organic matter and PAC contents, and soil organic matter mineralization were monitored during 5 months. Total bacteria and fungi, and PAH-ring hydroxylating dioxygenase genes were quantified. Results showed that PAHs and polar-PACs were degraded with different degradation dynamics. Differences in degradation rates were observed among the three soils depending on PAH distribution and availability. Overall, low molecular weight compounds were preferentially degraded. Degradation selectivity between isomers and structurally similar compounds was observed which could be used to check the efficiency of bioremediation processes. Bacterial communities were dominant over fungi and were most likely responsible for PAC degradation. Abundance of PAH-degrading bacteria increased during incubations, but their proportion in the bacterial communities tended to decrease. The accumulation of some oxygenated-PACs during the bioslurry experiment underlines the necessity to monitor these compounds during application of remediation treatment on PAH contaminated soils. Copyright © 2017 Elsevier B.V. All rights reserved.

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

Code of Federal Regulations, 2013 CFR

2013-07-01

.... Requirements as specified in § 721.80 (j) (use as an additive flame retardant for plastics) and (q). (iv... 40 Protection of Environment 32 2013-07-01 2013-07-01 false Brominated aromatic com-pound (generic... Specific Chemical Substances § 721.775 Brominated aromatic com-pound (generic name). (a) Chemical...

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

Code of Federal Regulations, 2014 CFR

2014-07-01

.... Requirements as specified in § 721.80 (j) (use as an additive flame retardant for plastics) and (q). (iv... 40 Protection of Environment 31 2014-07-01 2014-07-01 false Brominated aromatic com-pound (generic... Specific Chemical Substances § 721.775 Brominated aromatic com-pound (generic name). (a) Chemical...

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

Code of Federal Regulations, 2012 CFR

2012-07-01

.... Requirements as specified in § 721.80 (j) (use as an additive flame retardant for plastics) and (q). (iv... 40 Protection of Environment 32 2012-07-01 2012-07-01 false Brominated aromatic com-pound (generic... Specific Chemical Substances § 721.775 Brominated aromatic com-pound (generic name). (a) Chemical...

Fuel Composition and Performance Analysis of Endothermically Heated Fuels for Pulse Detonation Engines

DTIC Science & Technology

2009-03-01

Waste heat from a pulse detonation engine (PDE) was extracted via concentric, counter flow heat exchangers to produce supercritical pyrolytic...mass spectrometry HLPC = High performance liquid chromatography NPT = National pipe thread PAH = Polycyclic aromatic hydrocarbon PDE = Pulse...Precision Liquid Chromatography (HPLC). The resulting “stressed” fuel showed a 29 shift to lower molecular weight compounds, as well as the production

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.

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.

Fluorescence evolution of leachates during treatment processes from two contrasting landfills.

PubMed

Sun, W L; Liu, T T; Cui, F; Ni, J R

2008-10-01

Landfill leachates are composed of a complex mixture of organic matter, including a wide range of potentially fluorescent organic compounds. The fluorescence excitation-emission matrix (FEEM) of leachates during treatment processes is investigated. Particular attention is paid to the fluorescence evolution of leachates during treatment processes. Two typical types of landfill, landfill A (a direct municipal solid waste (MSW) landfill) and landfill B (disposal of bottom ashes from MSW incinerators), in a city in Southern China were selected. The results show that two characteristic and intense excitation-emission peaks located at Ex/Em = 310-330 nm/395-410 nm (peak alpha) and Ex/Em = 250-260 nm/450-460 nm (peak alpha') are observed. As the aromatic chemicals, capable of emitting fluorescence, are more recalcitrant to biodegradation than aliphatic chemicals, enhancement of the dissolved organic carbon normalized fluorescence intensities is demonstrated during treatment processes of leachate A and leachate B. This is confirmed by the variation of ultraviolet absorptivity of leachates at 254 nm. Peak alpha' and peak alpha are attributed to a mixture of xenobiotic organic compounds with low molecular weight and relatively stable aromatic fulvic-like matters with high molecular weight, respectively. Humic substances are more resistant to biodegradation than xenobiotic organic compounds, so a significant reduction in the Ialpha'/Ialpha values (fluorescence intensity ratios of peak alpha' and peak a) of leachate A was observed during treatment processes. However, no evident variation for the Ialpha/Ialpha values of leachate B was found during treatment processes owing to the low concentrations of xenobiotic organic compounds in leachate B after incineration.

Poly(arylene ether-co-imidazole)s as toughness modifiers for epoxy resins

NASA Technical Reports Server (NTRS)

Mcdaniel, Patricia D. (Inventor); Connell, John W. (Inventor)

1994-01-01

A toughened epoxy was prepared by reacting an epoxy resin with a poly(arylene ether-co-imidazole)s (PAEI). The epoxy resin comprises N,N,N',N'tetraglycidyl-4,4'- methylenebisbenzenamine and 4-aminophenyl sulfone. The PAEI was prepared by reacting an aromatic bisphenol, a bisphenol imidazole, and an activated aromatic dihalide or dinitro compound in the presence of potassium carbonate in a polar aprotic solvent at an elevated temperature. The epoxies which were modified with these particular PAEI's showed a significant increase in toughness with only a 10 weight percent loading of the PAEI into the epoxy. These toughened epoxies were used to prepare composites and molded parts.

Molecular-Scale Investigation with ESI-FT-ICR-MS on Fractionation of Dissolved Organic Matter Induced by Adsorption on Iron Oxyhydroxides.

PubMed

Lv, Jitao; Zhang, Shuzhen; Wang, Songshan; Luo, Lei; Cao, Dong; Christie, Peter

2016-03-01

Adsorption by minerals is a common geochemical process of dissolved organic matter (DOM) which may induce fractionation of DOM at the mineral-water interface. Here, we examine the molecular fractionation of DOM induced by adsorption onto three common iron oxyhydroxides using electrospray ionization coupled with Fourier-transform ion cyclotron resonance mass spectrometry (ESI-FT-ICR-MS). Ferrihydrite exhibited higher affinity to DOM and induced more pronounced molecular fractionation of DOM than did goethite or lepidocrocite. High molecular weight (>500 Da) compounds and compounds high in unsaturation or rich in oxygen including polycyclic aromatics, polyphenols and carboxylic compounds had higher affinity to iron oxyhydroxides and especially to ferrihydrite. Low molecular weight compounds and compounds low in unsaturation or containing few oxygenated groups (mainly alcohols and ethers) were preferentially maintained in solution. This study confirms that the double bond equivalence and the number of oxygen atoms are valuable parameters indicating the selective fractionation of DOM at mineral and water interfaces. The results of this study provide important information for further understanding the behavior of DOM in the natural environment.

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 [College Park, MD; Sidorov, Vladimir [Richmond, VA; Kotch, Frank W [New Phila., PA

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.

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. Copyright © 2015 Elsevier Inc. All rights reserved.

Natural attenuation and biosurfactant-stimulated bioremediation of estuarine sediments contaminated with diesel oil.

PubMed

Bayer, Débora M; Chagas-Spinelli, Alessandra C O; Gavazza, Sávia; Florencio, Lourdinha; Kato, Mario T

2013-09-01

We evaluated the bioremediation, by natural attenuation (NA) and by natural attenuation stimulated (SNA) using a rhamnolipid biosurfactant, of estuarine sediments contaminated with diesel oil. Sediment samples (30 cm) were put into 35 cm glass columns, and the concentrations of the 16 polycyclic aromatic hydrocarbons (PAHs) prioritized by the US Environmental Protection Agency were monitored for 111 days. Naphthalene percolated through the columns more than the other PAHs, and, in general, the concentrations of the lower molecular weight PAHs, consisting of two and three aromatic rings, changed during the first 45 days of treatment, whereas the concentrations of the higher molecular weight PAHs, consisting of four, five, and six rings, were more stable. The higher molecular weight PAHs became more available after 45 days, in the deeper parts of the columns (20-30 cm). Evidence of degradation was observed only for some compounds, such as pyrene, with a total removal efficiency of 82 and 78 % in the NA and SNA treatments, respectively, but without significant difference. In the case of total PAH removal, the efficiencies were significantly different of 82 and 67 %, respectively.

Retardation effect of nitrogen compounds and condensed aromatics on shale oil catalytic cracking processing and their characterization.

PubMed

Li, Nan; Chen, Chen; Wang, Bin; Li, Shaojie; Yang, Chaohe; Chen, Xiaobo

Untreated shale oil, shale oil treated with HCl aqueous solution and shale oil treated with HCl and furfural were used to do comparative experiments in fixed bed reactors. Nitrogen compounds and condensed aromatics extracted by HCl and furfural were characterized by electrospray ionization Fourier transform cyclotron resonance mass spectrometry and gas chromatography and mass spectrometry, respectively. Compared with untreated shale oil, the conversion and yield of liquid products increased considerably after removing basic nitrogen compounds by HCl extraction. Furthermore, after removing nitrogen compounds and condensed aromatics by both HCl and furfural, the conversion and yield of liquid products further increased. In addition, N 1 class species are predominant in both basic and non-basic nitrogen compounds, and they are probably indole, carbazole, cycloalkyl-carbazole, pyridine and cycloalkyl-pyridine. As for the condensed aromatics, most of them possess aromatic rings with two to three rings and zero to four carbon atom.

PERFLUORINATED AROMATIC COMPOUNDS

DTIC Science & Technology

decafluorodiphenylamine, 3,3’,4,4’-tetra substituted- hexafluorobiphenyls, tetrafluororesorcinol, perfluoroaromatic thioethers, and dithiols. These...and other perfluorinated aromatic compounds are the intermediates employed in the synthesis of perfluorinated model compounds and polymers.

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

Bond cleavage of lignin model compounds into aromatic monomers using supported metal catalysts in supercritical water

PubMed Central

Yamaguchi, Aritomo; Mimura, Naoki; Shirai, Masayuki; Sato, Osamu

2017-01-01

More efficient use of lignin carbon is necessary for carbon-efficient utilization of lignocellulosic biomass. Conversion of lignin into valuable aromatic compounds requires the cleavage of C–O ether bonds and C–C bonds between lignin monomer units. The catalytic cleavage of C–O bonds is still challenging, and cleavage of C–C bonds is even more difficult. Here, we report cleavage of the aromatic C–O bonds in lignin model compounds using supported metal catalysts in supercritical water without adding hydrogen gas and without causing hydrogenation of the aromatic rings. The cleavage of the C–C bond in bibenzyl was also achieved with Rh/C as a catalyst. Use of this technique may greatly facilitate the conversion of lignin into valuable aromatic compounds. PMID:28387304

Three-dimensional aromatic networks.

PubMed

Toyota, Shinji; Iwanaga, Tetsuo

2014-01-01

Three-dimensional (3D) networks consisting of aromatic units and linkers are reviewed from various aspects. To understand principles for the construction of such compounds, we generalize the roles of building units, the synthetic approaches, and the classification of networks. As fundamental compounds, cyclophanes with large aromatic units and aromatic macrocycles with linear acetylene linkers are highlighted in terms of transannular interactions between aromatic units, conformational preference, and resolution of chiral derivatives. Polycyclic cage compounds are constructed from building units by linkages via covalent bonds, metal-coordination bonds, or hydrogen bonds. Large cage networks often include a wide range of guest species in their cavity to afford novel inclusion compounds. Topological isomers consisting of two or more macrocycles are formed by cyclization of preorganized species. Some complicated topological networks are constructed by self-assembly of simple building units.

Characteristics of volatile organic compounds (VOCs) from the evaporative emissions of modern passenger cars

NASA Astrophysics Data System (ADS)

Yue, Tingting; Yue, Xin; Chai, Fahe; Hu, Jingnan; Lai, Yitu; He, Liqang; Zhu, Rencheng

2017-02-01

Volatile organic compounds (VOCs) from vehicle evaporative emissions contribute substantially to photochemical air pollution. Yet, few studies of the characteristics of VOCs emitted from vehicle evaporative emissions have been published. We investigate the characteristics of 57 VOCs in hot soak, 24 h diurnal and 48 h diurnal emissions by applying the Sealed Housing Evaporative Determination unit (SHED) test to three modern passenger cars (one US Tier 2 and two China IV vehicles) using two different types of gasoline. The characteristics of the VOCs from the hot soak, 24 h diurnal and 48 h diurnal emissions were different due to their different emission mechanisms. In the hot soak emissions, toluene, isopentane/n-pentane, and 2,2,4-trimethylpentane were dominant species. In the 24 h and 48 h diurnal emissions, isopentane and n-pentane were dominant species. Toluene was the third most dominant component in the 24 h diurnal emissions but decreased by a mass of 42%-80% in the 48 h diurnal emissions. In the hot soak, 24 h diurnal and 48 h diurnal emissions, alkanes were generally the dominant hydrocarbons, followed by aromatics and olefins. However, owing to different evaporative emission mechanisms, the weight percentages of the aromatic hydrocarbons decreased and the weight percentages of the alkanes increased from the hot soak test to the 24 h diurnal and 48 h diurnal tests for each vehicle. The dominant contributors to the ozone formation potentials (OFPs) were also different in the hot soak, 24 h diurnal and 48 h diurnal emissions. The OFPs (g O3/g VOC) of the hot soak emissions were higher than those of the 24 h and 48 h diurnal emissions. In addition, the combined effect of decreasing the olefin and aromatic contents of gasoline on vehicle evaporative emissions was investigated. The aromatics all decreased substantially in the hot soak, 24 h and 48 h diurnal emissions, and the total masses of the VOCs and OFPs decreased, with the greatest reduction occurring in the hot soak emissions when the fuel aromatic and olefin contents were reduced.

Concentrations of polynuclear aromatic hydrocarbons and inorganic constituents in ambient surface soils, Chicago, Illinois, 2001-02

USGS Publications Warehouse

Kay, Robert T.; Arnold, Terri L.; Cannon, William F.; Graham, David; Morton, Eric; Bienert, Raymond

2003-01-01

Polynuclear aromatic hydrocarbon (PAH) compounds are ubiquitous in ambient surface soils in the city of Chicago, Illinois. PAH concentrations in samples collected in June 2001 and January 2002 were typically in the following order from highest to lowest: fluoranthene, pyrene, benzo(b)fluoranthene, phenanthrene, benzo(a)pyrene, chrysene, benzo(a)anthracene, benzo(k)fluoranthene, indeno(1,2,3-cd)pyrene, benzo(g,h,i)perylene, dibenzo(a,h)anthracene, and anthracene. Naphthalene, acenaphthene, acenaphthylene, and fluorene were consistently at the lowest concentrations in each sample. Concentrations of the PAH compounds showed variable correlation. Concentrations of PAH compounds with higher molecular weights typically show a higher degree of correlation with other PAH compounds of higher molecular weight, whereas PAH compounds with lower molecular weights tended to show a lower degree of correlation with all other PAH compounds. These differences indicate that high and low molecular-weight PAHs behave differentl y once released into the environment. Concentrations of individual PAH compounds in soils typically varied by at least three orders of magnitude across the city and varied by more than an order of magnitude over a distance of about 1,000 feet. Concentrations of a given PAH in ambient surface soils are affected by a variety of site-specific factors, and may be affected by proximity to industrial areas. Concentrations of a given PAH in ambient surface soils did not appear to be affected the organic carbon content of the soil, proximity to non-industrial land use, or proximity to a roadway. The concentration of the different PAH compounds in ambient surface soils appears to be affected by the propensity for the PAH compound to be in the vapor or particulate phase in the atmosphere. Lower molecular-weight PAH compounds, which are primarily in the vapor phase in the atmosphere, were detected in lower concentrations in the surface soils. Higher molecular-weight PAH compounds, which are present primarily in the particulate phase in the atmosphere, tended to be in higher concentrations in the surface soils. The apparent effect of the PAH phase in the atmosphere on the concentration of a PAH in ambient surface soils indicates that atmospheric settling of particulate matter is an important source of the PAH compounds in ambient surface soils in Chicago. The distribution of PAH compounds within the city was complex. Comparatively high concentrations were detected near Lake Michigan in the northern part of the city, in much of the western part of the city, and in isolated areas in the southern part of the city. Concentrations were lower in much of the northwestern, south-central, southwestern, and far southern parts of the city. The arithmetic mean concentration of arsenic, mercury, calcium, magnesium, phosphorus, copper, molybdenum, zinc, and selenium was from 2 to 6 times higher in ambient surface soils in the city of Chicago than in soils from surrounding agricultural areas. The arithmetic mean concentration of lead in Chicago soils was about 20 times higher. Concentrations of calcium and magnesium above those of surrounding agricultural areas appear to be related to the effects of dolomite bedrock on the chemical composition of the soil. Elevated concentrations of the remaining elements listed above indicate a potential anthropogenic source(s) of these elements in Chicago soils.

Polynuclear aromatic hydrocarbon uptake by carrots grown in sludge-amended soil

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wild, S.R.; Jones, K.C.

The uptake of polynuclear aromatic hydrocarbons (PAHs) from sewage sludge-amended soils by carrots (Daucus carota) was investigated. Carrots were grown in control soils and soils amended with three sludge application rates, 15, 55, and 180 t/ha. Applied sludge contained 17.2 mg [summation]PAH/kg, a concentration typical for a sludge derived from a rural area. Carrot foliage, root peels and root cores were analyzed for 15 PAH compounds. Carrots foliage PAH concentrations were unaffected by sludge applications (PAH loadings), but root peel PAH concentrations increased to a plateau concentration with increasing soil PAH levels. Low molecular weight PAH compounds dominate dindividual componentsmore » of the [summation]PAH load in the root tissues. The PAH concentrations detected in the root peels were all significantly lower than in the foliage, which receives PAH inputs from the atmosphere. Carrot core [summation]PAH concentrations were unaffected by sludge application, implying little or no transfer of PAHs from the peels to the core. About 70% of the PAH burden found in carrots was associated with the peels. Fresh weight carrot core concentrations were all <4.2 [mu]g/kg. Overall, this investigation suggests that the risks posed to human health by PAHs applied in sewage sludge to arable soils are minimal.« less

Molecular evidence of heavy-oil weathering following the M/V Cosco Busan spill: insights from Fourier transform ion cyclotron resonance mass spectrometry.

PubMed

Lemkau, Karin L; McKenna, Amy M; Podgorski, David C; Rodgers, Ryan P; Reddy, Christopher M

2014-04-01

Recent studies have highlighted a critical need to investigate oil weathering beyond the analytical window afforded by conventional gas chromatography (GC). In particular, techniques capable of detecting polar and higher molecular weight (HMW; > 400 Da) components abundant in crude and heavy fuel oils (HFOs) as well as transformation products. Here, we used atmospheric pressure photoionization Fourier transform ion cyclotron resonance mass spectrometry (APPI FT-ICR MS) to identify molecular transformations in oil-residue samples from the 2007 M/V Cosco Busan HFO spill (San Francisco, CA). Over 617 days, the abundance and diversity of oxygen-containing compounds increased relative to the parent HFO, likely from bio- and photodegradation. HMW, highly aromatic, alkylated compounds decreased in relative abundance concurrent with increased relative abundance of less alkylated stable aromatic structures. Combining these results with GC-based data yielded a more comprehensive understanding of oil spill weathering. For example, dealkylation trends and the overall loss of HMW species observed by FT-ICR MS has not previously been documented and is counterintuitive given losses of lower molecular weight species observed by GC. These results suggest a region of relative stability at the interface of these techniques, which provides new indicators for studying long-term weathering and identifying sources.

Distribution, partition and removal of polycyclic aromatic hydrocarbons (PAHs) during coking wastewater treatment processes.

PubMed

Zhang, Wanhui; Wei, Chaohai; An, Guanfeng

2015-05-01

In this study, we report the performance of a full-scale conventional activated sludge (A-O1-O2) treatment in eliminating polycyclic aromatic hydrocarbons (PAHs). Both aqueous and solid phases along with the coking wastewater treatment processes were analyzed for the presence of 18 PAHs. It was found that the target compounds occurred widely in raw coking wastewater, treated effluent and sludge samples. In the coking wastewater treatment system, 4-5 ring PAHs were the dominant compounds, while 4 rings PAHs predominated in the sludge samples. Over 98% of the PAH removal was achieved in the coking wastewater treatment plant (WWTP), with the total concentration of PAHs being 21.3 ± 1.9 μg L(-1) in the final effluent. During the coking wastewater treatment processes, the association of the lower molecular weight PAH with suspended solids was generally less than 60%, while the association of higher molecular weight PAHs was greater than 90%. High distribution efficiencies (Kdp and Kds) were found, suggesting that adsorption was the potential removal pathway of PAHs. Finally, the mass balances of PAHs in various stages of the coking WWTP were obtained, and the results indicated that adsorption to sludge was the main removal pathway for PAHs in the coking wastewater treatment processes.

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-nitrophenols photolysis. The model results are compared with observations from different surface and aircraft campaigns in order to estimate the accuracy of the model.

Mass spectral analysis of long chain alkyl aromatic compounds synthesized from alpha-olefin alkylation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Cheng, M.T.; Hudson, J.D.

1994-12-31

Long chain alkyl aromatic compounds are important petrochemicals with many applications. They are generally synthesized by alkylating the corresponding aromatic nucleus. In this report, the authors will describe the mass spectral fragmentation of alkylphenols and alkylsalicylates.

[Component and content changes of volatiles from Chinese cabbage damaged by Plutella xylostella].

PubMed

Yang, Guang; You, Minsheng; Wei, Hui

2004-11-01

The study showed that Chinese cabbage, Brassica campestris could release a variety of volatiles, especially when infested by Plutella xylostella larvae. Among these volatiles, saturated hydrocarbon was dominant, aromatic hydrocarbon was the second, and unsaturated hydrocarbon, aldehyde, alcohol, ketone, acid and heteroaromatic compounds were existed with a small amount. Chinese cabbage damaged by Plutella xylostella larvae produced 3 times of volatiles in amount with more species than the control. The volatiles from control plants were mostly of small molecular weight, and those from Chinese cabbage damaged by Plutella xylostella were mostly of high molecular weight.

Graphene-based materials via benzidine-assisted exfoliation and reduction of graphite oxide and their electrochemical properties

NASA Astrophysics Data System (ADS)

Vermisoglou, E. C.; Giannakopoulou, T.; Romanos, G.; Boukos, N.; Psycharis, V.; Lei, C.; Lekakou, C.; Petridis, D.; Trapalis, C.

2017-01-01

Benzidine, a compound bearing aromatic rings and terminal amino groups, was employed for the intercalation and simultaneous reduction of graphite oxide (GO). The aromatic diamine can be intercalated into GO as follows: (1) by grafting with the epoxy groups of GO, (2) by hydrogen bonding with the oxygen containing groups of GO. Stacking between benzidine aromatic rings and unoxidized domains of GO may occur through π-π interaction. The role of benzidine is influenced by pH conditions and the weight ratio GO/benzidine. Two weight ratios were tested i.e. 1:2 and 1:3. Under strong alkaline conditions through K2CO3 addition (pH ∼10.4-10.6) both intercalation and reduction of GO via amino groups occur, while under strong acidic conditions through HCl addition (pH ∼1.4-2.2) π-π stacking is preferred. When no base or acid is added (pH ∼5.2) and the weight ratio is 1:2, there are indications that reduction and π-π stacking occur, while at a GO/benzidine weight ratio 1:3 intercalation via amino groups and reduction seem to dominate. The aforementioned remarks render benzidine a multifunctional tool towards production of reduced graphene oxide. The effect of pH conditions and the GO/benzidine weight ratio on the quality and the electrochemical properties of the produced graphene-based materials were investigated. Cyclic voltammetry measurements using three-electrode cell and KCl aqueous solution as an electrolyte gave specific capacitance values up to ∼178 F/g. When electric double-layer capacitors (EDLC) were fabricated from these materials, the maximum capacitance in organic electrolyte i.e., tetraethyl ammonium tetrafluoroborate (TEABF4) in polycarbonate (PC) was ∼29 F/g.

Oxidative decomposition of aromatic hydrocarbons by electron beam irradiation

NASA Astrophysics Data System (ADS)

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

2003-05-01

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

Aromatic Amino Acid-Derived Compounds Induce Morphological Changes and Modulate the Cell Growth of Wine Yeast Species

PubMed Central

González, Beatriz; Vázquez, Jennifer; Cullen, Paul J.; Mas, Albert; Beltran, Gemma; Torija, María-Jesús

2018-01-01

Yeasts secrete a large diversity of compounds during alcoholic fermentation, which affect growth rates and developmental processes, like filamentous growth. Several compounds are produced during aromatic amino acid metabolism, including aromatic alcohols, serotonin, melatonin, and tryptamine. We evaluated the effects of these compounds on growth parameters in 16 different wine yeasts, including non-Saccharomyces wine strains, for which the effects of these compounds have not been well-defined. Serotonin, tryptamine, and tryptophol negatively influenced yeast growth, whereas phenylethanol and tyrosol specifically affected non-Saccharomyces strains. The effects of the aromatic alcohols were observed at concentrations commonly found in wines, suggesting a possible role in microbial interaction during wine fermentation. Additionally, we demonstrated that aromatic alcohols and ethanol are able to affect invasive and pseudohyphal growth in a manner dependent on nutrient availability. Some of these compounds showed strain-specific effects. These findings add to the understanding of the fermentation process and illustrate the diversity of metabolic communication that may occur among related species during metabolic processes. PMID:29696002

Molecular-beam, mass-spectrometric studies of wood vapor and model compounds over HZSM-5 catalyst

NASA Astrophysics Data System (ADS)

Evans, Robert J.; Milne, Thomas A.

1987-11-01

The use of molecular beam mass spectrometry (MBMS) for the real time screening of wood pyrolysis product conversion over Mobil's HZSM-5 catalyst allows the evaluation of the performance of different catalysts, reaction conditions and feedstocks. This information can help guide more extensive testing at the bench scale level and provide insight into the chemistry of conversion. The following conclusions can be drawn from the work to date: (1) there can be no breakthrough of primary wood vapor organics until the weight of wood/weight of the catalyst is 1; (2) there are few intermediates from wood on the way to alkenes, light aromatics, and naphthalenes; (3) the light aromatics/alkenes ration is 1 for the nonoptimized conditions studied to date; (4) much of the oxygen is favorably rejected as CO and CO sub 2; (5) the coke yield is about 10 percent in these experiments; and (6) methanol is a poor model for wood because the mechanism of hydrocarbon formation is apparently different.

Leaching of polycyclic aromatic hydrocarbons from oil shale processing waste deposit: a long-term field study.

PubMed

Jefimova, Jekaterina; Irha, Natalya; Reinik, Janek; Kirso, Uuve; Steinnes, Eiliv

2014-05-15

The leaching behavior of selected polycyclic aromatic hydrocarbons (PAHs) from an oil shale processing waste deposit was monitored during 2005-2009. Samples were collected from the deposit using a special device for leachate sampling at field conditions without disturbance of the upper layers. Contents of 16 priority PAHs in leachate samples collected from aged and fresh parts of the deposit were determined by GC-MS. The sum of the detected PAHs in leachates varied significantly throughout the study period: 19-315 μg/l from aged spent shale, and 36-151 μg/l from fresh spent shale. Among the studied PAHs the low-molecular weight compounds phenanthrene, naphthalene, acenaphthylene, and anthracene predominated. Among the high-molecular weight PAHs benzo[a]anthracene and pyrene leached in the highest concentrations. A spent shale deposit is a source of PAHs that could infiltrate into the surrounding environment for a long period of time. Copyright © 2014 Elsevier B.V. All rights reserved.

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.

GLOBAL INVENTORY OF VOLATILE COMPOUND EMISSIONS FROM ANTHROPOGENIC SOURCES

EPA Science Inventory

The report describes a global inventory anthropogenic volatile organic compound (VOC) emissions that includes a separate inventory for each of seven pollutant groups--paraffins, olefins, aromatics, formaldehyde, other aldehydes, other aromatics, and marginally reactive compounds....

New Findings on Aromatic Compounds' Degradation and Their Metabolic Pathways, the Biosurfactant Production and Motility of the Halophilic Bacterium Halomonas sp. KHS3.

PubMed

Corti Monzón, Georgina; Nisenbaum, Melina; Herrera Seitz, M Karina; Murialdo, Silvia E

2018-04-24

The study of the aromatic compounds' degrading ability by halophilic bacteria became an interesting research topic, because of the increasing use of halophiles in bioremediation of saline habitats and effluents. In this work, we focused on the study of aromatic compounds' degradation potential of Halomonas sp. KHS3, a moderately halophilic bacterium isolated from hydrocarbon-contaminated seawater of the Mar del Plata harbour. We demonstrated that H. sp. KHS3 is able to grow using different monoaromatic (salicylic acid, benzoic acid, 4-hydroxybenzoic acid, phthalate) and polyaromatic (naphthalene, fluorene, and phenanthrene) substrates. The ability to degrade benzoic acid and 4-hydroxybenzoic acid was analytically corroborated, and Monod kinetic parameters and yield coefficients for degradation were estimated. Strategies that may enhance substrate bioavailability such as surfactant production and chemotactic responses toward aromatic compounds were confirmed. Genomic sequence analysis of this strain allowed us to identify several genes putatively related to the metabolism of aromatic compounds, being the catechol and protocatechuate branches of β-ketoadipate pathway completely represented. These features suggest that the broad-spectrum xenobiotic degrader H. sp. KHS3 could be employed as a useful biotechnological tool for the cleanup of aromatic compounds-polluted saline habitats or effluents.

Effects of weathering on biological marker and aromatic hydrocarbon composition of organic matter in Phosphoria shale outcrop

USGS Publications Warehouse

Clayton, J.L.; King, J.D.

1987-01-01

GC-MS analyses were performed on core samples collected from a shale outcrop of the Permian Phosphoria Formation in Utah, U.S.A., to study effects of weathering on selected biological marker and aromatic (phenanthrene) hydrocarbon compounds. Among the biological markers, the most important weathering effects are a decrease in the 20S 20R diastereomer ratio of the C29 steranes and loss of low molecular weight triaromatic steroids. A decrease in the C19 through C22 tricylcic terpanes occurs relative to the total C19-C26 tricyclic fraction. Pronounced loss of methyl-substituted phenanthrenes occurs relative to phenanthrene. No major effect on the overall distribution of pentacyclic terpanes is evident. ?? 1987.

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 small part of the overall worker exposure to asphalt fume, on average less than 0.07% of the benzene-soluble fraction. Measurements of benzene-soluble fraction were uniformly below the American Conference of Governmental Industrial Hygienists' Threshold Limit Value for asphalt fume.

Petroleum pollution in mangrove forests sediments from Qeshm Island and Khamir Port-Persian Gulf, Iran.

PubMed

Ebrahimi-Sirizi, Zohreh; Riyahi-Bakhtiyari, Alireza

2013-05-01

The concentrations of total polycyclic aromatic hydrocarbons (PAHs) and 22 individual PAH compounds in 42 surface sediments collected from the mangrove forest of Qeshm Island and Khamir Port (Persian Gulf) were analyzed. PAHs concentrations ranged from 259 to 5,376 ng g(-1) dry weight with mean and median values of 1,585 and 1,146 ng g(-1), respectively. The mangrove sediments had higher percentages of lower molecular weight PAHs and the PAH profiles were dominated by naphthalene. Ratio values of specific PAH compounds were calculated to evaluate the possible source of PAH contamination. This ratios suggesting that the mangrove sediments have a petrogenic input of PAHs. Sediment quality guidelines were conducted to assess the toxicity of PAH compounds. The levels of total PAHs at all of stations except one station, namely Q6, were below the effects range low. Also, concentrations of naphthalene in some stations exceeded the effects range median.

Evolution of interstellar organic compounds under asteroidal hydrothermal conditions

NASA Astrophysics Data System (ADS)

Vinogradoff, V.; Bernard, S.; Le Guillou, C.; Remusat, L.

2018-05-01

Carbonaceous chondrites (CC) contain a diversity of organic compounds. No definitive evidence for a genetic relationship between these complex organic molecules and the simple organic molecules detected in the interstellar medium (ISM) has yet been reported. One of the many difficulties arises from the transformations of organic compounds during accretion and hydrothermal alteration on asteroids. Here, we report results of hydrothermal alteration experiments conducted on a common constituent of interstellar ice analogs, Hexamethylenetetramine (HMT - C6H12N4). We submitted HMT to asteroidal hydrothermal conditions at 150 °C, for various durations (up to 31 days) and under alkaline pH. Organic products were characterized by gas chromatography mass spectrometry, infrared spectroscopy and synchrotron-based X-ray absorption near edge structure spectroscopy. Results show that, within a few days, HMT has evolved into (1) a very diverse suite of soluble compounds dominated by N-bearing aromatic compounds (> 150 species after 31 days), including for instance formamide, pyridine, pyrrole and their polymers (2) an aromatic and N-rich insoluble material that forms after only 7 days of experiment and then remains stable through time. The reaction pathways leading to the soluble compounds likely include HMT dissociation, formose and Maillard-type reactions, e.g. reactions of sugar derivatives with amines. The present study demonstrates that, if interstellar organic compounds such as HMT had been accreted by chondrite parent bodies, they would have undergone chemical transformations during hydrothermal alteration, potentially leading to the formation of high molecular weight insoluble organic molecules. Some of the diversity of soluble and insoluble organic compounds found in CC may thus result from asteroidal hydrothermal alteration.

The chemical structure of macromolecular fractions of a sulfur-rich oil

NASA Astrophysics Data System (ADS)

Richnow, Hans H.; Jenisch, Angela; Michaelis, Walter

1993-06-01

A selective stepwise chemical degradation has been developed for structural studies of highmolecularweight (HMW) fractions of sulfur-rich oils. The degradation steps are: (i) desulfurization (ii) cleavage of oxygen-carbon bonds (iii) oxidation of aromatic structural units. After each step, the remaining macromolecular matter was subjected to the subsequent reaction. This degradation scheme was applied to the asphaltene, the resin and a macromolecular fraction of low polarity (LPMF) of the Rozel Point oil. Total amounts of degraded low-molecular-weight compounds increased progressively in the order asphaltene < resin < LPMF. Desulfurization yielded mainly phytane, steranes and triterpanes. Oxygen-carbon bond cleavage resulted in hydrocarbon fractions predominated by n-alkanes and acyclic isoprenoids. The oxidation step afforded high amounts of linear carboxylic acids in the range of C 11 to C 33. The released compounds provide a more complete picture of the molecular structure of the oil fractions than previously available. Labelling experiments with deuterium atoms allowed to characterize the site of bonding and the type of linkage for the released compounds. Evidence is presented that subunits of the macromolecular network are attached simultaneously by oxygen and sulfur (n-alkanes, hopanes) or by sulfur and aromatic units ( n-alkanes, steranes).

Desulfurization of benzonaphthothiophenes and dibenzothiophene with a Raney nickel catalyst and its relationship to the. pi. -electron density

DOE Office of Scientific and Technical Information (OSTI.GOV)

Nagai, M.; Urimoto, H.; Uetake, K.

The hydrodesulfurization of heavy petroleum feedstocks and coal-derived liquids requires the conversion of high molecular weight compounds like dibenzothiophene and benzonaphthothiophenes. There are several studies in the literature which deal with the mechanism of the hydrodesulfurization of multi-ring thiophenic compounds on cobalt or nickel molybdenum catalysts at high pressure. However, there are only a few studies which relate the chemical reactivity of these compounds to their electronic structure. The reactivity of a multi-ring sulfur-containing compound is not determined solely by the size of the molecule. In addition, others studied the relationship between the first step in the hydrotreating reaction ofmore » benzonaphthothiophene and the Coulombic interaction term of the compounds using the CNDO/S method. Because there is competition between the different processes (hydrogenation and desulfurization) during reaction, it is difficult to understand the relationship between desulfurization and the electronic properties of the compounds under reaction conditions. The calculation of electronic structures necessarily involves many sigma bonds of hydrogenated aromatic rings as well as many electrons of high molecular weight compounds. For this reason, it is best to select a catalyst and reaction conditions under which desulfurization takes place without hydrogenation.« less

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)

Multi-Phase Equilibrium and Solubilities of Aromatic Compounds and Inorganic Compounds in Sub- and Supercritical Water: A Review.

PubMed

Liu, Qinli; Ding, Xin; Du, Bowen; Fang, Tao

2017-11-02

Supercritical water oxidation (SCWO), as a novel and efficient technology, has been applied to wastewater treatment processes. The use of phase equilibrium data to optimize process parameters can offer a theoretical guidance for designing SCWO processes and reducing the equipment and operating costs. In this work, high-pressure phase equilibrium data for aromatic compounds+water systems and inorganic compounds+water systems are given. Moreover, thermodynamic models, equations of state (EOS) and empirical and semi-empirical approaches are summarized and evaluated. This paper also lists the existing problems of multi-phase equilibria and solubility studies on aromatic compounds and inorganic compounds in sub- and supercritical water.

Tracking changes in composition and amount of dissolved organic matter throughout drinking water treatment plants by comprehensive two-dimensional gas chromatography-quadrupole mass spectrometry.

PubMed

Li, Chunmei; Wang, Donghong; Xu, Xiong; Xu, Meijia; Wang, Zijian; Xiao, Ruiyang

2017-12-31

Dissolved organic matter (DOM) can affect the performance of water treatment processes and produce undesirable disinfection by-products during disinfection. Several studies have been undertaken on the structural characterization of DOM, but its fate during drinking water treatment processes is still not fully understood. In this work, the nontargeted screening method of comprehensive two-dimensional gas chromatography-quadrupole mass spectrometry (GC×GC-qMS) was used to reveal the detailed changes of different chemical classes of compounds in DOM during conventional and advanced drinking water treatment processes at three drinking water treatment plants in China. The results showed that when the dissolved organic carbon removal was low, shifts in the DOM composition could not be detected with the specific ultraviolet absorbance at 254nm, but the changes were clear in the three-dimensional fluorescence excitation-emission matrix or GC×GC-qMS analyses. Coagulation-sedimentation processes selectively removed 37-59% of the nitrogenous compounds, alcohols and aromatic hydrocarbons but increased the concentrations of halogen-containing compounds by 17-26% because of the contact time with chlorine in this step. Filtration was less efficient at removing DOM but preferentially removed 21-60% of the acids. However, other organic matter would be released from the filter (e.g., nitrogenous compounds, acids, and aromatic hydrocarbons). Biological activated carbon (BAC) treatment removed most of the compounds produced from ozonation, particularly ketones, alcohols, halogen-containing compounds and acids. However, it should be noted that certain highly polar or high molecular weight compounds not identified in this study might be released from the BAC bed. After the whole treatment processes, the concentrations of nitrogenous compounds, alcohols, alkenes, aromatic hydrocarbons and ketones were decreased more by the advanced treatment processes than by the conventional treatment processes. Alcohol and ketone removals were probably related to the reduction in protein-like materials. Alkane removal was probably related to the reduction in fulvic acid-like and humic acid-like materials. Copyright © 2017 Elsevier B.V. All rights reserved.

Construction and Optimization of a Heterologous Pathway for Protocatechuate Catabolism in Escherichia coli Enables Bioconversion of Model Aromatic Compounds

DOE Office of Scientific and Technical Information (OSTI.GOV)

Clarkson, Sonya M.; Giannone, Richard J.; Kridelbaugh, Donna M.

The production of biofuels from lignocellulose yields a substantial lignin by-product stream that currently has few applications. Biological conversion of lignin-derived compounds into chemicals and fuels has the potential to improve the economics of lignocellulose-derived biofuels, but few microbes are able both to catabolize lignin-derived aromatic compounds and to generate valuable products. WhileEscherichia colihas been engineered to produce a variety of fuels and chemicals, it is incapable of catabolizing most aromatic compounds. Therefore, we engineeredE. colito catabolize protocatechuate, a common intermediate in lignin degradation, as the sole source of carbon and energy via heterologous expression of a nine-gene pathway fromPseudomonasmore » putidaKT2440. Then, we used experimental evolution to select for mutations that increased growth with protocatechuate more than 2-fold. Increasing the strength of a single ribosome binding site in the heterologous pathway was sufficient to recapitulate the increased growth. After optimization of the core pathway, we extended the pathway to enable catabolism of a second model compound, 4-hydroxybenzoate. These engineered strains will be useful platforms to discover, characterize, and optimize pathways for conversions of lignin-derived aromatics. IMPORTANCELignin is a challenging substrate for microbial catabolism due to its polymeric and heterogeneous chemical structure. Therefore, engineering microbes for improved catabolism of lignin-derived aromatic compounds will require the assembly of an entire network of catabolic reactions, including pathways from genetically intractable strains. By constructing defined pathways for aromatic compound degradation in a model host would allow rapid identification, characterization, and optimization of novel pathways. Finally, we constructed and optimized one such pathway inE. colito enable catabolism of a model aromatic compound, protocatechuate, and then extended the pathway to a related compound, 4-hydroxybenzoate. This optimized strain can now be used as the basis for the characterization of novel pathways.« less

Construction and Optimization of a Heterologous Pathway for Protocatechuate Catabolism in Escherichia coli Enables Bioconversion of Model Aromatic Compounds.

PubMed

Clarkson, Sonya M; Giannone, Richard J; Kridelbaugh, Donna M; Elkins, James G; Guss, Adam M; Michener, Joshua K

2017-09-15

The production of biofuels from lignocellulose yields a substantial lignin by-product stream that currently has few applications. Biological conversion of lignin-derived compounds into chemicals and fuels has the potential to improve the economics of lignocellulose-derived biofuels, but few microbes are able both to catabolize lignin-derived aromatic compounds and to generate valuable products. While Escherichia coli has been engineered to produce a variety of fuels and chemicals, it is incapable of catabolizing most aromatic compounds. Therefore, we engineered E. coli to catabolize protocatechuate, a common intermediate in lignin degradation, as the sole source of carbon and energy via heterologous expression of a nine-gene pathway from Pseudomonas putida KT2440. We next used experimental evolution to select for mutations that increased growth with protocatechuate more than 2-fold. Increasing the strength of a single ribosome binding site in the heterologous pathway was sufficient to recapitulate the increased growth. After optimization of the core pathway, we extended the pathway to enable catabolism of a second model compound, 4-hydroxybenzoate. These engineered strains will be useful platforms to discover, characterize, and optimize pathways for conversions of lignin-derived aromatics. IMPORTANCE Lignin is a challenging substrate for microbial catabolism due to its polymeric and heterogeneous chemical structure. Therefore, engineering microbes for improved catabolism of lignin-derived aromatic compounds will require the assembly of an entire network of catabolic reactions, including pathways from genetically intractable strains. Constructing defined pathways for aromatic compound degradation in a model host would allow rapid identification, characterization, and optimization of novel pathways. We constructed and optimized one such pathway in E. coli to enable catabolism of a model aromatic compound, protocatechuate, and then extended the pathway to a related compound, 4-hydroxybenzoate. This optimized strain can now be used as the basis for the characterization of novel pathways. Copyright © 2017 American Society for Microbiology.

Weathering trend characterization of medium-molecular weight polycyclic aromatic disulfur heterocycles by Fourier transform ion cyclotron resonance mass spectrometry.

PubMed

Hegazi, Abdelrahman H; Fathalla, Eiman M; Andersson, Jan T

2014-09-01

Different weathering factors act to change petroleum composition once it is spilled into the environment. n-Alkanes, biomarkers, low-molecular weight polyaromatic hydrocarbons and sulfur heterocycles compositional changing in the environment have been extensively studied by different researchers and many parameters have been used for oil source identification and monitoring of weathering and biological degradation processes. In this work, we studied the fate of medium-molecular weight polycyclic aromatic disulfur heterocycles (PAS2Hs), up to ca. 900Da, of artificially weathered Flotta North Sea crude oil by ultra high-resolution Fourier transform ion cyclotron resonance mass spectrometry. It was found that PAS2Hs in studied crude oil having double bond equivalents (DBE) from 5 to 8 with a mass range from ca 316 to 582Da were less influenced even after six months artificial weathering experiment. However, compounds having DBEs 12, 11 and 10 were depleted after two, four and six months weathering, respectively. In addition, DBE 9 series was more susceptible to weathering than those of DBE 7 and 8. Copyright © 2014 Elsevier Ltd. All rights reserved.

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.

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.

Biodegradation of Nitriles in Shale Oil

PubMed Central

Aislabie, Jackie; Atlas, Ronald M.

1988-01-01

Enrichment cultures were obtained, after prolonged incubation on a shale oil as the sole source of nitrogen, that selectively degraded nitriles. Capillary gas chromatographic analyses showed that the mixed microbial populations in the enrichments degraded the homologous series of aliphatic nitriles but not the aliphatic hydrocarbons, aromatic hydrocarbons, or heterocyclic-nitrogen compounds found in this oil. Time course studies showed that lighter nitriles were removed more rapidly than higher-molecular-weight nitriles. A Pseudomonas fluorescens strain isolated from an enrichment, which was able to completely utilize the individual nitriles undecyl cyanide and undecanenitrile as sole sources of carbon and nitrogen, was unable to attack stearonitrile when provided alone as the growth substrate. A P. aeruginosa strain, also isolated from one of the enrichments, used nitriles but not aliphatic or aromatic hydrocarbons when the oil was used as a sole nitrogen source. However, when the shale oil was used as the sole source of carbon, aliphatic hydrocarbons in addition to nitriles were degraded but aromatic hydrocarbons were still not attacked by this P. aeruginosa strain. PMID:16347731

Development of a flameproof elastic elastomeric fiber

NASA Technical Reports Server (NTRS)

Howarth, J. T.; Nilgrom, J.; Massucco, A.; Sheth, S. G.; Dawn, F. S.

1971-01-01

Various flexible polyurethane structures containing halogen were synthesized from polyesters derived from aliphatic or aromatic polyols and dibasic acids. Aliphatic halide structures could not be used because they are unstable at the required reaction temperatures, giving of hydrogen halide which hydrolyzes the ester linkages. In contract, halogen-containing aromatic polyols were stable and satisfactory products were made. The most promising composition, a brominated neopentyl glycol capped with toluene disocyanate, was used as a conventional diisocyanate, in conjunction with hydroxy-terminated polyethers or polyesters to form elastomeric urethanes containing about 10% bromine with weight. Products made in this manner will not burn in air, have an oxygen index value of about 25, and have tensile strength values of about 5,000 psi at 450% elongation. The most efficient additives for imparting flame retardancy to Spandex urethanes are aromatic halides and the most effective of these are the bromide compounds. Various levels of flame retardancy have been achieved depending on the levels of additives used.

Renewable platform chemicals from directional microwave-assisted liquefaction coupling stepwise extraction of waste biomass.

PubMed

Feng, Junfeng; Hse, Chungyun; Yang, Zhongzhi; Wang, Kui; Jiang, Jianchun; Xu, Junming

2017-11-01

Directional microwave-assisted liquefaction and stepwise extraction are introduced for producing platform chemicals: aromatics and monosaccharides. When sulfuric acid was used as a catalyst, a 45% monosaccharides yield and a 29% aromatics yield were obtained from bamboo with 0.3g catalyst per 18g methanol and 2g bamboo at 160°C with 10min. Approximately 78-86wt% of the six biomass materials were converted into liquid products. After the stepwise extraction and precipitation process, the yields of monosaccharide derivatives and three phenolic compound fractions were 39-45% and 28-32%, respectively. Monosaccharides from holocellulose collected with a high purity of methyl glycosides were higher than 90%. Aromatic derivatives with different weight-molecular distributions were separated into three fractions with more than 80% phenolics. As their similar chemical properties within each fraction, platform chemicals have great commercial potential for producing high-quality chemicals and biofuels using mild upgrading conditions. Copyright © 2017. Published by Elsevier Ltd.

Partitioning studies of coal-tar constituents in a two-phase contaminated ground-water system

USGS Publications Warehouse

Rostad, C.E.; Pereira, W.E.; Hult, M.F.

1985-01-01

Organic compounds derived from coal-tar wastes in a contaminated aquifer in St. Louis Park, Minnesota, were identified, and their partition coefficients between the tar phase and aqueous phase were determined and compared with the corresponding n-octanol/water partition coefficients. Coal tar contains numerous polycyclic aromatic compounds, many of which are suspected carcinogens or mutagens. Groundwater contamination by these toxic compounds may pose an environmental health hazard in nearby public water-supply wells. Fluid samples from this aquifer developed two phases upon settling: an upper aqueous phase, and a lower oily-tar phase. After separating the phases, polycyclic aromatic compounds in each phase were isolated using complexation with N-methyl-2-pyrrolidone and identified by fused-silica capillary gas chromatography/mass spectrometry. Thirty-one of the polycyclic aromatic compounds were chosen for further study from four different classes: 12 polycyclic aromatic hydrocarbons, 10 nitrogen heterocycles, 5 sulfur heterocycles, and 4 oxygen heterocycles. Within each compound class, the tar/water partition coefficients of these compounds were reasonably comparable with the respective n-octanol/water partition coefficient.

Pyrolysis of virgin and waste polypropylene and its mixtures with waste polyethylene and polystyrene.

PubMed

Kiran Ciliz, Nilgun; Ekinci, Ekrem; Snape, Colin E

2004-01-01

A comparison of waste and virgin polypropylene (PP) plastics under slow pyrolysis conditions is presented. Moreover, mixtures of waste PP with wastes of polyethylene (PE) and polystyrene (PS) were pyrolyzed under the same operating conditions. Not only the impact of waste on degradation products but also impacts of the variations in the mixing ratio were investigated. The thermogravimetric weight loss curves and their derivatives of virgin and waste PP showed differences due to the impurities which are dirt and food residues. The liquid yield distribution concerning the aliphatic, mono-aromatic and poly-aromatic compounds varies as the ratio of PP waste increases in the waste plastic mixtures. In addition to this, the alkene/alkane ratio of gas products shows variations depending on the mixing ratio of wastes.

Aromatic ring generation as a dust precursor in acetylene discharges

NASA Astrophysics Data System (ADS)

De Bleecker, Kathleen; Bogaerts, Annemie; Goedheer, Wim

2006-04-01

Production of aromatic hydrocarbon compounds as an intermediate step for particle formation in low-pressure acetylene discharges is investigated via a kinetic approach. The detailed chemical reaction mechanism contains 140 reactions among 55 species. The cyclic hydrocarbon chemistry is mainly based on studies of polycyclic aromatic hydrocarbon formation in cosmic environments. The model explicitly includes organic chain, cyclic molecules, radicals, and ions up to a size of 12 carbon atoms. The calculated density profiles show that the aromatic formation yields are quite significant, suggesting that aromatic compounds play a role in the underlying mechanisms of particle formation in hydrocarbon plasmas.

Low severity coal conversion by ionic hydrogenation: Quarterly report, October--December 1988

DOE Office of Scientific and Technical Information (OSTI.GOV)

Maioriello, J.; Larsen, J.W.

1988-12-31

A newly developed reaction system consisting of H/sub 2/O:BF/sub 3//H/sub 2//(CH/sub 3/CN)/sub 2/PtCl/sub 2/ was applied to the ionic hydrogenation of aromatic and functionalized aromatic compounds. Hydrogenations were carried out in this aqueous system at 50/degree/C and 500 psi H/sub 2/. Aryl ethers were hydrogenated and cleaved, yielding deoxygenated, fully saturated compounds as the major products. Reactions of nitrogen-containing aromatic compounds resulted in partial saturation of aromatic rings without cleavage of the C-N bonds. Aromatic and PNA compounds can be fully or partially hydrogenated depending on their structures. Aromatic thiols, sulfides and thiophenes poison the catalyst; the oxidized sulfur formsmore » (sulfonic acids, sulfones) were not reduced and did not poison the catalyst. It was found that certain aromatic compounds were easier to hydrogenate than others. Ionic hydrogenation of Wyodak cola using a H/sub 2/O:BF/sub 3//H/sub 2//(MeCN)/sub 2/PtCl/sub 2/ resulted in no significant increase in THF extractability (5.8--9.6% THF-extractables, wt) over that of the parent coal (4.6--6.7% THF-extractables, wt). Ionic hydrogenation of a demineralized Wyodak coal (1 M aq. citric acid, reflux 1 day) resulted in a slight increase in THF extractability (10.4%) over the untreated parent coal (5.6--5.8%). 4 refs., 1 fig., 1 tab.« less

Toxicity of N-substituted aromatics to acetoclastic methanogenic activity in granular sludge

DOE Office of Scientific and Technical Information (OSTI.GOV)

Donlon, B.A.; Razo-Flores, E.; Field, J.A.

1995-11-01

N-substituted aromatics are important priority pollutants entering the environment primarily through anthropogenic activities associated associated with the industrial production of dyes, explosives, pestides, and pharmaceuticals. Anaerobic treatment of wastewaters discharged by these industries could potentially be problematical as a result of the high toxicity of N-substituted aromatics. The objective of this study was to examine the structure-toxicity relationship of N-substituted aromatic compounds to acetoclastic methanogenic bacteria. The toxicity was assayed to serum flasks by measuring methane production in granular sludge. Unacclimated cultures were used to minimize the biotransformation of the toxic organic chemicals during the test. The nature and themore » degree of the aromatic substitution were observed to have a profound effect on the toxicity of the test compound. Nitroaromatic compounds were, on the average, over 500-fold more toxic than their corresponding aromatic amines. Considering the facile reduction of nitro groups by anerobic microorganisms, a dramatic detoxification of nitroaromatics towards methanogens can be expected to occur during anaerobic wastewater treatment. While the toxicity exerted by the N-substituted aromatic compounds was closely correlated with compound apolarity (log P), it was observed that at any given log P, N-substituted phenols had a toxicity that was 2 orders of magnitude higher than that of chlorophenols and alkylphenols. This indicates that toxicity due to the chemical reactivity of nitroaromatics is much more important than partitioning effects in bacterial membranes. 41 refs., 3 figs., 1 tab.« less

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. Copyright © 2013 Wiley Periodicals, Inc.

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

Interactions of low molecular weight aromatic acids and amino acids with goethite, kaolinite and bentonite with or without organic matter coating

NASA Astrophysics Data System (ADS)

Gao, Jiajia; Jansen, Boris; Cerli, Chiara; Kalbitz, Karsten

2015-04-01

Interaction of organic matter molecules with the soil's solid phase is a key factor influencing the stabilization of carbon in soils and thus forms a crucial aspect of the global carbon cycle. While subject of much research attention so far, we still have much to learn about such interactions at the molecular level; in particular in the light of competition between different classes of organic molecules and in the presence of previously adsorbed soil organic matter. We studied the interaction of a group of low molecular weight (LMW) aromatic acids (salicylic, syringic, vanillic and ferulic acid) and amino acids (lysine, glutamic, leucine and phenylalanine) on goethite, kaolinite and bentonite with and without previously adsorbed dissolved organic matter (DOM). For this we used batch experiments at pH = 6.0 where some of the organic compounds were positively charged (i.e. lysine) or negatively charged (i.e. glutamic and salicylic acid) while the minerals also displayed positively (i.e. goethite) or negatively charged surfaces (i.e. bentonite). We found much higher sorption of salicylic acid and lysine than other compounds. On the bare minerals we found a great variety of sorption strength, with salicylic acid strongly adsorbed, while syringic, vanillic and ferulic acid showed little or no adsorption. For the amino acids, protonated lysine showed a stronger affinity to negatively charged kaolinite and bentonite than other amino acids. While deprotonated glutamic acid showed the strongest adsorption on goethite. Leucine and phenylalanine showed hardly any adsorption on any of the minerals. When present concurrently, amino acids decreased the sorption of salicylic acid on the three types of mineral, while the presence of LMW aromatic acids increased the sorption of lysine on kaolinite and bentonite and the sorption of glutamic acid on goethite. The presence of previously adsorbed DOM reduced the sorption of salicylic acid and lysine. The results confirm that interactions of different classes of organic molecules with solid soil phases cannot be understood in isolation, but must be interpreted in the context of the presence of other classes of molecules. It seems that the presence of methoxy groups decreases the adsorption of aromatic acids to minerals. We did not find evidence for protein conditioning of any mineral surface, i.e. increased adsorption of aromatic acids after adsorption of amino acids.

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.

Biodegradation of aromatic compounds by white rot and ectomycorrhizal fungal species and the accumulation of chlorinated benzoic acid in ectomycorrhizal pine seedlings.

PubMed

Dittmann, Jens; Heyser, Wolfgang; Bücking, Heike

2002-10-01

The capability of different white rot (WR, Heterobasidion annosum, Phanerochaete chrysosporium, Trametes versicolor) and ectomycorrhizal (ECM, Paxillus involutus, Suillus bovinus) fungal species to degrade different aromatic compounds and the absorption of 3-chlorobenzoic acid (3-CBA) by ECM pine seedlings was examined. The effect of aromatic compounds on the fungal biomass development varied considerably and depended on (a) the compound, (b) the external concentration, and (c) the fungal species. The highest effect on the fungal biomass development was observed for 3-CBA. Generally the tolerance of WR fungi against aromatic compounds was higher than that of the biotrophic fungal species. The capability of different fungi to degrade aromatic substances varied between the species but not generally between biotrophic and saprotrophic fungi. The highest degradation capability for aromatic compounds was detected for T. versicolor and H. annosum, whereas for Phanerochaete chrysosporium and the ECM fungi lower degradation rates were found. However, Paxillus involutus and S. bovinus showed comparable degradation rates at low concentrations of benzoic acid and 4-hydroxybenzoic acid. In contrast to liquid cultures, where no biodegradation of 3-CBA by S. bovinus was observed, mycorrhizal pines inoculated with S. bovinus showed a low capability to remove 3-CBA from soil substrates. Additional X-ray microanalytical investigations showed, that 3-CBA supplied to mycorrhizal plants was accumulated in the root cell cytoplasm and is translocated across the endodermis to the shoot of mycorrhizal pine seedlings.

Monitoring of polycyclic aromatic hydrocarbons on agricultural lands surrounding Tehran oil refinery.

PubMed

Bayat, J; Hashemi, S H; Khoshbakht, K; Deihimfard, R; Shahbazi, A; Momeni-Vesalian, R

2015-07-01

Soil samples at two depths were collected and analyzed to determine the concentrations of 16 polycyclic aromatic hydrocarbons (PAHs), organic carbon, and soil pH. The Σ16PAHs were 0.13 to 3.92 mg kg(-1) at depth 1 and 0.21 to 50.32 mg kg(-1)at depth 2. The averages of the PAH compounds indicate that the area is contaminated with oil, and this pollution was greater at depth 2. Interpolation maps showed that the southern region, especially at depth 2, has been contaminated more by anthropogenic activity. The diagnostic ratios indicate several sources of pollution of the agricultural soil. A comparison of average PAHs and standard values revealed that higher molecular weight compounds in the topsoil (InP and BghiP) and subsoil (BaA, BkF, BaP, DBA, and BghiP) exceed standard values for farmland. The pH interpolation map for both depths showed that most of the area has alkaline soil from long-term irrigation with untreated urban wastewater.

Characterization of VOC Sources during the Texas Air Quality Study 2000 Using Proton-Transfer-Reaction Mass Spectrometry

NASA Astrophysics Data System (ADS)

Karl, T.; Jobson, T.; William, K.; Williams, E.; Stutz, J.; Goldan, P.; Fall, R.; Fehsenfeld, F.; Lindinger, W.

2002-12-01

We used Proton-Transfer-Reaction Mass Spectrometry (PTR-MS) for continuous real-time monitoring of volatile organic compounds (VOCs) at a site near the Houston Ship Channel during the Texas Air Quality Study 2000. Anthropogenic aromatics, alkenes, methanol, acetaldehyde, formaldehyde, acetone/propanal, a C7-Ketone, HCN and acrylonitrile were the most prominent compounds observed. Propene was the most abundant light-weight hydrocarbon detected by this technique, and was highly correlated with its oxidation products, formaldehyde and acetaldehyde, with typical propene-acetaldehyde ratios close to 1 in propene-dominated plumes. In the case of aromatic species the high time resolution of the obtained dataset helped in identifying different anthropogenic sources (e.g. industrial from urban emissions) and testing current emission inventories. In addition, a comparison with results from complimentary techniques (gas chromatography, differential optical absorption spectroscopy) was used to assess the selectivity of this on-line technique in a complex urban and industrial VOC matrix and give an interpretation of mass scans obtained by `soft' chemical ionization using proton-transfer via H3O+.

Effect of interlayer cations of montmorillonite on the biodegradation and adsorption of crude oil polycyclic aromatic compounds.

PubMed

Ugochukwu, Uzochukwu C; Manning, David A C; Fialips, Claire I

2014-09-01

Cation exchange capacity, surface acidity and specific surface area are surface properties of clay minerals that make them act as catalysts or supports in most biogeochemical processes hence making them play important roles in environmental control. However, the role of homoionic clay minerals during the biodegradation of polycyclic aromatic compounds is not well reported. In this study, the effect of interlayer cations of montmorillonites in the removal of some crude oil polycyclic aromatic compounds during biodegradation was investigated in aqueous clay/oil microcosm experiments with a hydrocarbon degrading microorganism community. The homoionic montmorillonites were prepared via cation exchange reactions by treating the unmodified montmorillonite with the relevant metallic chloride. The study indicated that potassium-montmorillonite and zinc-montmorillonite did not enhance the biodegradation of the polycyclic aromatic hydrocarbons whereas calcium-montmorillonite, and ferric-montmorillonite enhanced their biodegradation significantly. Adsorption of polycyclic aromatic hydrocarbons was significant during biodegradation with potassium- and zinc-montmorillonite where there was about 45% removal of the polycyclic aromatic compounds by adsorption in the experimental microcosm containing 5:1 ratio (w/w) of clay to oil. Copyright © 2014 Elsevier Ltd. All rights reserved.

Pt- and Pd-decorated MWCNTs for vapour and gas detection at room temperature

PubMed Central

Baccar, Hamdi; Clément, Pierrick; Abdelghani, Adnane

2015-01-01

Summary Here we report on the gas sensing properties of multiwalled carbon nanotubes decorated with sputtered Pt or Pd nanoparticles. Sputtering allows for an oxygen plasma treatment that removes amorphous carbon from the surface of the carbon nanotubes and creates oxygenated surface defects in which metal nanoparticles nucleate within a few minutes. The decoration with the 2 nm Pt or the 3 nm Pd nanoparticles is very homogeneous. This procedure is performed at the device level (i.e., for carbon nanotubes deposited onto sensor substrates) for many devices in one batch, which illustrates the scalability for the mass production of affordable nanosensors. The response to selected aromatic and non-aromatic volatile organic compounds, as well as pollutant gases has been studied. Pt- and Pd-decorated multiwalled carbon nanotubes show a fully reversible response to the non-aromatic volatile organic compounds tested when operated at room temperature. In contrast, these nanomaterials were not responsive to the aromatic compounds studied (measured at concentrations up to 50 ppm). Therefore, these sensors could be useful in a small, battery-operated alarm detector, for example, which is able to discriminate aromatic from non-aromatic volatile organic compounds in ambient. PMID:25977863

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ijam, M.J.; Al-Qatami, S.Y.; Arif, S.F.

For several decades removal of aromatics from crude oil fractions has been practiced in oil refining to produce fuels and lubricants of lower aromatic content and hence of improved quality. These aromatics are suitable raw materials for the manufacture of aromatic solvents, aromatic process oils, high octane gasoline, and as basic materials for making detergents, perfumes and dyes. A study for the UV and IR spectra of the aromatic hydrocarbons showed them to consist mainly of bi-, tri-, tetra-, and penta-substituted benzene, bicyclic and tricyclic compounds. Detailed studies have been reported of molecular structure and substituent effects have been reportedmore » on the retention characteristics of aromatic hydrocarbons on alumina, silica and various chemically bonded silicas containing {minus}C{sub 18}, {minus}NH{sub 2}, {minus}R(NH){sub 2}, {minus}CN, RCN, and phenyl-mercuric acetate for compound class (ring-numbered) high performance liquid chromatography separation. With the aid of a Finnegan type 9612-4000 GC/MS apparatus, the mixture of neutral + basic aromatic hydrocarbons was qualitatively identified and revealed the presence of more than 112 peaks. The neutral + basic aromatic hydrocarbons consist mainly of: 3.68% monoaromatics (C{sub 3} - C{sub 6} alkyl benzenes), 52.81% bicycloaromatics (C{sub 0} - C{sub 4} alkylnaphthalenes), 6.20% tricycloaromatics (C{sub 0} - C{sub 4} alkyl phenanthrenes), and 37.32% nonhydrocarbons aromatic compounds. The components in major HPLC peaks corresponding to bicycloaromatics were further separated into small groups (3-4 components in each) by HPLC using an ODS-reverse phase-C{sub 18} column. To separate a single component from the mixture is a difficult problem. The individual compounds in the separated fractions were identified by GC/MS (Hewlett Packard 5993 system).« less

Direct Aqueous Photochemistry of Isoprene High-NOx Secondary Organic Aerosol

DOE Office of Scientific and Technical Information (OSTI.GOV)

Nguyen, Tran B.; Laskin, Alexander; Laskin, Julia

2012-05-17

Secondary organic aerosol (SOA) generated from the high-NOx photooxidation of isoprene was dissolved in water and irradiated with {lambda} > 290 nm light to simulate direct photolytic processing of organics in atmospheric water droplets. High-resolution mass spectrometry was used to characterize the composition at four time intervals (0, 1, 2, and 4 h). Photolysis resulted in the decomposition of high molecular weight (MW) oligomers, reducing the average length of organics by 2 carbon units. Approximately 65% by count of SOA molecules decomposed during photolysis, accompanied by the formation of new products. An average of 30 % of the organic massmore » was modified after 4 h of direct photolysis. In contrast, only a small fraction of the mass (<2 %), belonging primarily to organic nitrates, decomposed in the absence of irradiation by hydrolysis. We observed a statistically-significant increase in average O/C, decrease in H/C, and increase in N/C ratios resulting from photolysis. Furthermore, the concentration of aromatic compounds increased significantly during photolysis. Approximately 10 % of photodegraded compounds and 50 % of the photoproducts contain nitrogen. Organic nitrates and multifunctional oligomers were identified as compounds degraded by photolysis. Low-MW 0N (compounds with 0 nitrogen atoms in their structure) and 2N compounds were the dominant photoproducts. Fragmentation experiments using tandem mass spectrometry (MSn, n = 2-3) indicate that the 2N products are likely heterocyclic/aromatic and are tentatively identified as furoxans. Although the exact mechanism is unclear, these 2N heterocyclic compounds are produced by reactions between photochemically-formed aqueous NOx species and SOA organics.« less

Effectiveness of Liquid-Liquid Extraction, Solid Phase Extraction, and Headspace Technique for Determination of Some Volatile Water-Soluble Compounds of Rose Aromatic Water

PubMed Central

2017-01-01

Steam distillation is used to isolate scent of rose flowers. Rose aromatic water is commonly used in European cuisine and aromatherapy besides its use in cosmetic industry for its lovely scent. In this study, three different sampling techniques, liquid-liquid extraction (LLE), headspace technique (HS), and solid phase extraction (SPE), were compared for the analysis of volatile water-soluble compounds in commercial rose aromatic water. Some volatile water-soluble compounds of rose aromatic water were also analyzed by gas chromatography mass spectrometry (GCMS). In any case, it was concluded that one of the solid phase extraction methods led to higher recoveries for 2-phenylethyl alcohol (PEA) in the rose aromatic water than the liquid-liquid extraction and headspace technique. Liquid-liquid extraction method provided higher recovery ratios for citronellol, nerol, and geraniol than others. Ideal linear correlation coefficient values were observed by GCMS for quantitative analysis of volatile compounds (r2 ≥ 0.999). Optimized methods showed acceptable repeatability (RSDs < 5%) and excellent recovery (>95%). For compounds such as α-pinene, linalool, β-caryophyllene, α-humulene, methyl eugenol, and eugenol, the best recovery values were obtained with LLE and SPE. PMID:28791049

Spectroscopic identification and anti-biofilm properties of polar metabolites from the medicinal plant Helichrysum italicum against Pseudomonas aeruginosa.

PubMed

D'Abrosca, Brigida; Buommino, Elisabetta; D'Angelo, Grazia; Coretti, Lorena; Scognamiglio, Monica; Severino, Valeria; Pacifico, Severina; Donnarumma, Giovanna; Fiorentino, Antonio

2013-11-15

Two new acylated styrylpyrones, one 5-methoxy-1(3H)-isobenzofuranone glucoside and a hydroxymethyl-orcinol derivative, along with sixteen known aromatic metabolites, including lignans, quinic acid derivatives low-molecular weight phenol glucosides, have been isolated from the methanol extract of Helichrysum italicum, a medicinal plant typical of the Mediterranean vegetation. The structures of these compounds have been elucidated on the basis of extensive 2D-NMR spectroscopic analyses, including COSY, TOCSY, HSQC, CIGAR-HMBC, H2BC and HSQC-TOCSY, along with Q-TOF HRMS(2) analysis. Selected compounds were evaluated for their anti-biofilm properties against Pseudomonas aeruginosa. Copyright © 2013. Published by Elsevier Ltd.

Can Baird's and Clar's Rules Combined Explain Triplet State Energies of Polycyclic Conjugated Hydrocarbons with Fused 4nπ- and (4n + 2)π-Rings?

PubMed

Ayub, Rabia; Bakouri, Ouissam El; Jorner, Kjell; Solà, Miquel; Ottosson, Henrik

2017-06-16

Compounds that can be labeled as "aromatic chameleons" are π-conjugated compounds that are able to adjust their π-electron distributions so as to comply with the different rules of aromaticity in different electronic states. We used quantum chemical calculations to explore how the fusion of benzene rings onto aromatic chameleonic units represented by biphenylene, dibenzocyclooctatetraene, and dibenzo[a,e]pentalene modifies the first triplet excited states (T 1 ) of the compounds. Decreases in T 1 energies are observed when going from isomers with linear connectivity of the fused benzene rings to those with cis- or trans-bent connectivities. The T 1 energies decreased down to those of the parent (isolated) 4nπ-electron units. Simultaneously, we observe an increased influence of triplet state aromaticity of the central 4n ring as given by Baird's rule and evidenced by geometric, magnetic, and electron density based aromaticity indices (HOMA, NICS-XY, ACID, and FLU). Because of an influence of triplet state aromaticity in the central 4nπ-electron units, the most stabilized compounds retain the triplet excitation in Baird π-quartets or octets, enabling the outer benzene rings to adapt closed-shell singlet Clar π-sextet character. Interestingly, the T 1 energies go down as the total number of aromatic cycles within a molecule in the T 1 state increases.

MOLECULAR BASIS OF BIODEGRADATION OF CHLOROAROMATIC COMPOUNDS

EPA Science Inventory

Chlorinated aromatic hydrocarbons are widely used in industry and agriculture, and comprise the bulk of environmental pollutants. Although simple aromatic compounds are biodegradable by a variety of degradative pathways, their halogenated counterparts are more resistant to bacter...

Saccharomyces cerevisiae Mixed Culture of Blackberry (Rubus ulmifolius L.) Juice: Synergism in the Aroma Compounds Production

PubMed Central

Ragazzo-Sánchez, Juan Arturo; Ortiz-Basurto, Rosa Isela; Luna-Solano, Guadalupe; Calderón-Santoyo, Montserrat

2014-01-01

Blackberry (Rubus sp.) juice was fermented using four different strains of Saccharomyces cerevisiae (Vitilevure-CM4457, Enoferm-T306, ICV-K1, and Greroche Rhona-L3574) recognized because of their use in the wine industry. A medium alcoholic graduation spirit (<6°GL) with potential to be produced at an industrial scale was obtained. Alcoholic fermentations were performed at 28°C, 200 rpm, and noncontrolled pH. The synergistic effect on the aromatic compounds production during fermentation in mixed culture was compared with those obtained by monoculture and physic mixture of spirits produced in monoculture. The aromatic composition was determined by HS-SPME-GC. The differences in aromatic profile principally rely on the proportions in aromatic compounds and not on the number of those compounds. The multivariance analysis, principal component analysis (PCA), and factorial discriminant analysis (DFA) permit to demonstrate the synergism between the strains. PMID:25506606

The aromatic amino acids biosynthetic pathway: A core platform for products

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lievense, J.C.; Frost, J.W.

The aromatic amino acids biosynthetic pathway is viewed conventionally and primarily as the source of the amino acids L-tyrosine, L-phenylalanine. The authors have recognized the expanded role of the pathway as the major source of aromatic raw materials on earth. With the development of metabolic engineering approaches, it is now possible to biosynthesize a wide variety of aromatic compounds from inexpensive, clean, abundant, renewable sugars using fermentation methods. Examples of already and soon-to-be commercialized biosynthesis of such compounds are described. The long-term prospects are also assessed.

Biodegradation of organic pollutants in saline wastewater by halophilic microorganisms: a review.

PubMed

Castillo-Carvajal, Laura C; Sanz-Martín, José Luis; Barragán-Huerta, Blanca E

2014-01-01

Agro-food, petroleum, textile, and leather industries generate saline wastewater with a high content of organic pollutants such as aromatic hydrocarbons, phenols, nitroaromatics, and azo dyes. Halophilic microorganisms are of increasing interest in industrial waste treatment, due to their ability to degrade hazardous substances efficiently under high salt conditions. However, their full potential remains unexplored. The isolation and identification of halophilic and halotolerant microorganisms from geographically unrelated and geologically diverse hypersaline sites supports their application in bioremediation processes. Past investigations in this field have mainly focused on the elimination of polycyclic aromatic hydrocarbons and phenols, whereas few studies have investigated N-aromatic compounds, such as nitro-substituted compounds, amines, and azo dyes, in saline wastewater. Information regarding the growth conditions and degradation mechanisms of halophilic microorganisms is also limited. In this review, we discuss recent research on the removal of organic pollutants such as organic matter, in terms of chemical oxygen demand (COD), dyes, hydrocarbons, N-aliphatic and N-aromatic compounds, and phenols, in conditions of high salinity. In addition, some proposal pathways for the degradation of aromatic compounds are presented.

High Molecular Weight Petrogenic and Pyrogenic Hydrocarbons in Aquatic Environments

NASA Astrophysics Data System (ADS)

Abrajano, T. A., Jr.; Yan, B.; O'Malley, V.

2003-12-01

Geochemistry is ultimately the study of sources, movement, and fate of chemicals in the geosphere at various spatial and temporal scales. Environmental organic geochemistry focuses such studies on organic compounds of toxicological and ecological concern (e.g., Schwarzenbach et al., 1993, 1998; Eganhouse, 1997). This field emphasizes not only those compounds with potential toxicological properties, but also the geological systems accessible to the biological receptors of those hazards. Hence, the examples presented in this chapter focus on hydrocarbons with known health and ecological concern in accessible shallow, primarily aquatic, environments.Modern society depends on oil for energy and a variety of other daily needs, with present mineral oil consumption throughout the 1990s exceeding 3×109 t yr-1 (NRC, 2002). In the USA, e.g., ˜40% of energy consumed and 97% of transportation fuels are derived from oil. In the process of extraction, refinement, transport, use, and waste production, a small but environmentally significant fraction of raw oil materials, processed products, and waste are released inadvertently or purposefully into the environment. Because their presence and concentration in the shallow environments are often the result of human activities, these organic materials are generally referred to as "environmental contaminants." Although such reference connotes some form of toxicological or ecological hazard, specific health or ecological effects of many organic "environmental contaminants" remain to be demonstrated. Some are, in fact, likely innocuous at the levels that they are found in many systems, and simply adds to the milieu of biogenic organic compounds that naturally cycle through the shallow environment. Indeed, virtually all compounds in crude oil and processed petroleum products have been introduced naturally to the shallow environments as oil and gas seepage for millions of years ( NRC, 2002). Even high molecular weight (HMW) polyaromatic compounds were introduced to shallow environments through forest fires and natural coking of crude oil ( Ballentine et al., 1996; O'Malley et al., 1997). The full development of natural microbial enzymatic systems that can utilize HMW hydrocarbons as carbon or energy source attests to the antiquity of hydrocarbon dispersal processes in the environment. The environmental concern is, therefore, primarily due to the rate and spatial scale by which petroleum products are released in modern times, particularly with respect to the environmental sensitivity of some ecosystems to these releases ( Schwarzenbach et al., 1993; Eganhouse, 1997; NRC, 2002).Crude oil is produced by diagenetic and thermal maturation of terrestrial and marine plant and animal materials in source rocks and petroleum reservoirs. Most of the petroleum in use today is produced by thermal and bacterial decomposition of phytoplankton material that once lived near the surface of the world's ocean, lake, and river waters (Tissot and Welte, 1984). Terrestrially derived organic matter can be regionally significant, and is the second major contributor to the worldwide oil inventory ( Tissot and Welte, 1984; Peters and Moldowan, 1993; Engel and Macko, 1993). The existing theories hold that the organic matter present in crude oil consists of unconverted original biopolymers and new compounds polymerized by reactions promoted by time and increasing temperature in deep geologic formations. The resulting oil can migrate from source to reservoir rocks where the new geochemical conditions may again lead to further transformation of the petrogenic compounds. Any subsequent changes in reservoir conditions brought about by uplift, interaction with aqueous fluids, or even direct human intervention (e.g., drilling, water washing) likewise could alter the geochemical makeup of the petrogenic compounds. Much of our understanding of environmental sources and fate of hydrocarbon compounds in shallow environments indeed borrowed from the extensive geochemical and analytical framework that was meticulously built by petroleum geochemists over the years (e.g., Tissot and Welte, 1984; Peters et al., 1992; Peters and Moldowan, 1993; Engel and Macko, 1993; Moldowan et al., 1995; Wang et al., 1999; Faksness et al., 2002).Hydrocarbon compounds present in petroleum or pyrolysis by-products can be classified based on their composition, molecular weight, organic structure, or some combination of these criteria. For example, a report of the Committee on Intrinsic Remediation of the US NRC classified organic contaminants into HMW hydrocarbons, low molecular weight (LMW) hydrocarbons, oxygenated hydrocarbons, halogenated aliphatics, halogenated aromatics, and nitroaromatics (NRC, 2000). Hydrocarbons are compounds comprised exclusively of carbon and hydrogen and they are by far the dominant components of crude oil, processed petroleum hydrocarbons (gasoline, diesel, kerosene, fuel oil, and lubricating oil), coal tar, creosote, dyestuff, and pyrolysis waste products. These hydrocarbons often occur as mixtures of a diverse group of compounds whose behavior in near-surface environments is governed by their chemical structure and composition, the geochemical conditions and media of their release, and biological factors, primarily microbial metabolism, controlling their transformation and degradation.Hydrocarbons comprise from 50% to 99% of compounds present in refined and unrefined oil, and compounds containing other elements such as oxygen, nitrogen, and sulfur are present in relatively smaller proportions. Hydrocarbon compounds have carbons joined together as single C - C bonds (i.e., alkanes), double or triple C=C bonds (i.e., alkenes or olefins), or via an aromatic ring system with resonating electronic structure (i.e., aromatics). Alkanes, also called paraffins, are the dominant component of crude oil, with the carbon chain forming either straight (n-alkanes), branched (iso-alkanes), or cyclic (naphthenes) arrangement of up to 60 carbons (Figure 1). Aromatic compounds are the second major component of crude oil, with asphalthenes, consisting of stacks of highly polymerized aromatic structures (average of 16 rings), completing the list of major oil hydrocarbon components. Also shown in Figure 1 are several important classes of compounds that are extensively used in "fingerprinting" crude oil or petroleum sources: sterols derived from steroid, hopanol derived from bacteriohopanetetrols, and pristane and phytane derived from phytol (from chlorophyll) during diagenesis.

Distribution and sources of polycyclic aromatic hydrocarbon (PAH) in marine environment of China

NASA Astrophysics Data System (ADS)

Zheng, Jinshu; Richardson, Bruce J.; Shouming, O.; Zheng, Jianhua

2004-06-01

Polycyclic aromatic hydrocarbons (PAHs) are potentially carcinogenic and mutagenic compounds that have raised considerable environmental concern. The highest concentrations of PAHs in the coastal sediment samples in China was 5.8 11.0μg/g (dry weight) in the core from the Huangpu River, Shanghai. The second highest concentration of PAHs was 4.42μg/g (dry weight) in surface sediment of Victoria Harbour in Hong Kong, and 5.73μg/g (dry weight) in sediment of Jiaozhou Bay, Qingdao City. The low concentrations of PAHs were always in the sediments far away from industrial zones and cities, and ranged from 0.10 to 0.30μg/g (dry weight). Several environmental parameters are considered for the identification of sources of PAHs in marine environment. High proportion of naphthalene, low molecular weight PAHs and alkylated PAHs, plus high ratio of phenanthrene to anthracene (>15) and low ratio of fluoranthene to pyrene (<1) suggested a petrogenic source. According to these parameters, the Changjiang (Yangtze) River estuary of Shanghai, Jiaozhou Bay of Qingdao City, Zhujiang (Pearl) River mouth, Jiulong River mouth and most of Hong Kong coastal waters were heavily contaminated by PAHs from petrogenic sources. However, PAHs in rural coastal areas were dominated by pyrolytic origin PAHs. This review clearly showed that oil pollution and incomplete combustion of oil, coal and biomass are the main reason for PAHs anormalies in the study areas.

Natural Mediators in the Oxidation of Polycyclic Aromatic Hydrocarbons by Laccase Mediator Systems

PubMed Central

Johannes, Christian; Majcherczyk, Andrzej

2000-01-01

The oxidation of polycyclic aromatic compounds was studied in systems consisting of laccase from Trametes versicolor and so-called mediator compounds. The enzymatic oxidation of acenaphthene, acenaphthylene, anthracene, and fluorene was mediated by various laccase substrates (phenols and aromatic amines) or compounds produced and secreted by white rot fungi. The best natural mediators, such as phenol, aniline, 4-hydroxybenzoic acid, and 4-hydroxybenzyl alcohol were as efficient as the previously described synthetic compounds ABTS [2,2′-azino-bis-(3-ethylbenzothiazoline-6-sulfonic acid)] and 1-hydroxybenzotriazole. The oxidation efficiency increased proportionally with the redox potentials of the phenolic mediators up to a maximum value of 0.9 V and decreased thereafter with redox potentials exceeding this value. Natural compounds such as methionine, cysteine, and reduced glutathione, containing sulfhydryl groups, were also active as mediator compounds. PMID:10653713

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. Published by Elsevier B.V.

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 ...

Anaerobic Microbial Transformation of Aromatic Hydrocarbons and Mixtures of Aromatic Hydrocarbons and Halogenated Solvents

DTIC Science & Technology

1992-08-25

concentrations of these compounds may be toxic or Inhibitory to the microflora, especially if the microorganisms have not been exposed to these compounds before...Slow acclimation of the microflora to lower concentrations of these compounds , that occur at the outskirts of contamination plumes, gradually...sulfate may impair the capability of the microorganisms to degrade these compounds , although anaerobic respiration -- in theory -- is more favorable

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.

Evidence for behavioral attractiveness of methoxylated aromatics in a dynastid scarab beetle-pollinated araceae.

PubMed

Dötterl, Stefan; David, Anja; Boland, Wilhelm; Silberbauer-Gottsberger, Ilse; Gottsberger, Gerhard

2012-12-01

Many plants attract their pollinators with floral scents, and these olfactory signals are especially important at night, when visual signals become inefficient. Dynastid scarab beetles are a speciose group of night-active pollinators, and several plants pollinated by these insects have methoxylated aromatic compounds in their scents. However, there is a large gap in our knowledge regarding the compounds responsible for beetle attraction. We used chemical analytical analyses to determine temporal patterns of scent emission and the composition of scent released from inflorescences of Philodendron selloum. The attractiveness of the main components in the scent to the dynastid scarab beetle Erioscelis emarginata, the exclusive pollinator of this plant, was assessed in field biotests. The amount of scent increased rapidly in the evening, and large amounts of scent were released during the activity time of the beetle pollinators. Inflorescences emitted a high number of compounds of different biosynthetic origin, among them both uncommon and also widespread flower scents. Methoxylated aromatic compounds dominated the scent, and 4-methoxystyrene, the most abundant compound, attracted E. emarginata beetles. Other compounds, such as (Z)-jasmone and possibly also the methoxylated aromatic compound 3,4-dimethoxystyrene increased the attractiveness of 4-methoxystyrene. Methoxylated aromatics, which are known from other dynastid pollinated plants as well, are important signals in many scarab beetles in a different context (e.g., pheromones), thus suggesting that these plants exploit pre-existing preferences of the beetles for attracting this group of insects as pollinators.

DNA-damage effect of polycyclic aromatic hydrocarbons from urban area, evaluated in lung fibroblast cultures.

PubMed

Teixeira, Elba Calesso; Pra, Daniel; Idalgo, Daniele; Henriques, João Antonio Pêgas; Wiegand, Flavio

2012-03-01

This study was designed to biomonitor the effect of PAH extracts from urban areas on the DNA of lung cell cultures. The analyses of the polycyclic aromatic hydrocarbons (PAHs) were performed in atmospheric PM(2.5) and PM(10) collected at three sampling sites with heavy traffic located in the Metropolitan Area of Porto Alegre (MAPA) (Brazil). The concentrations of 16 major PAHs were determined according to EPA. Comet assay on V79 hamster lung cells was chosen for genotoxicity evaluation. Temperature, humidity, and wind speed were recorded. With regard to the damage index, higher levels were reported in the extract of particulate matter samples from the MAPA during the summer. High molecular weight compounds showed correlation with DNA damage frequency and their respective carcinogenicity. Copyright © 2011. Published by Elsevier Ltd.

Comparative investigation of low-molecular-weight fulvic acids of different origin by SEC-Q-TOF-ms: new insights into structure and formation.

PubMed

Reemtsma, Thorsten; These, Anja

2005-05-15

Size exclusion chromatography (SEC) coupled to electrospray ionization quadrupole time-of-flight mass spectrometry (ESI-Q-TOF-MS) was used to analyze the elemental composition and structure of low-molecular-weight fulvic acid molecules. It is shown that the set of hundreds of individual molecules form a homogeneous and structurally unique class of compounds that can be clearly differentiated from any other class of biogenic matter investigated to date. The molecular composition of low-molecular-weight fulvic acids in isolates of very different origin (surface water, groundwater, peat) is virtually indistinguishable. Significant and characteristic differences are, however, recognized when qualitative information and quantitative information provided by ESI-Q-TOF-MS are linked to each other. The relative frequency of the various molecules in each mixture can differ significantly, with the peat showing higher intensity of the aromatic and less carboxylated molecules of this set, whereas the aquatic fulvic acids show a strong contribution of the molecules with less aromaticity and a higher carboxylate content. The identity of fulvic acid molecules in isolates of different origin implies that no specific source material is required forfulvic acid formation but that they may be formed from different sources by different oxidative processes.

Redox shuttles having an aromatic ring fused to a 1,1,4,4-tetrasubstituted cyclohexane ring

DOEpatents

Weng, Wei; Zhang, Zhengcheng; Amine, Khalil

2015-12-01

An electrolyte includes an alkali metal salt; an aprotic solvent; and a redox shuttle additive including an aromatic compound having at least one aromatic ring fused with at least one non-aromatic ring, the aromatic ring having two or more oxygen or phosphorus-containing substituents.

Incombustible resin composition

NASA Technical Reports Server (NTRS)

Akima, T.

1982-01-01

Incombustible resin compositions composed of aromatic compounds were obtained through (1) combustion polymer material and (2) bisphenol A or halogenated bisphenol A and bisphenol A diglycidl ether or halogenated bisphenol A diglycidyl ether. The aromatic compound is an adduct of bifunctional phenols and bifunctional epoxy resins.

Reactions of aromatic diazonium salts with unsaturated compounds in the presence of nucleophiles

NASA Astrophysics Data System (ADS)

Grishchuk, B. D.; Gorbovoi, P. M.; Ganushchak, N. I.; Dombrovskii, A. V.

1994-03-01

The review surveys the reactions of aromatic diazonium salts with diene and monounsaturated compounds in the presence of nucleophiles. Certain further reactions of the reaction products and their application are considered. The bibliography includes 63 references.

Dendrimer encapsulated Silver nanoparticles as novel catalysts for reduction of aromatic nitro compounds

NASA Astrophysics Data System (ADS)

Asharani, I. V.; Thirumalai, D.; Sivakumar, A.

2017-11-01

Polyethylene glycol (PEG) core dendrimer encapsulated silver nanoparticles (AgNPs) were synthesized through normal chemical reduction method, where dendrimer acts as reducing and stabilizing agent. The encapsulated AgNPs were well characterized using TEM, DLS and XPS techniques. The synthesized AgNPs showed excellent catalytic activity towards the reduction of aromatic nitro compounds with sodium borohydride as reducing agent and the results substantiate that dendrimer encapsulated AgNPs can be an effective catalyst for the substituted nitro aromatic reduction reactions. Also the kinetics of different nitro compounds reductions was studied and presented.

Superficial distribution of aromatic compounds and geomicrobiology of sediments from Suruí Mangrove, Guanabara Bay, RJ, Brazil.

PubMed

Fontana, Luiz F; da Silva, Frederico S; de Figueiredo, Natália G; Brum, Daniel M; Netto, Annibal D Pereira; de Gigueiredo Junior, Alberto G; Crapez, Mirian A C

2010-12-01

The distribution of selected aromatic compounds and microbiology were assessed in superficial sediments from Suruí Mangrove, Guanabara Bay. Samples were collected at 23 stations, and particle size, organic matter, aromatic compounds, microbiology activity, biopolymers, and topography were determined. The concentration of aromatic compounds was distributed in patches over the entire mangrove, and their highest total concentration was determinated in the mangrove's central area. Particle size differed from most mangroves in that Suruí Mangrove has chernies on the edges and in front of the mangrove, and sand across the whole surface, which hampers the relationship between particle size and hydrocarbons. An average @ 10% p/p of organic matter was obtained, and biopolymers presented high concentrations, especially in the central and back areas of the mangrove. The biopolymers were distributed in high concentrations. The presence of fine sediments is an important factor in hydrocarbon accumulation. With high concentration of organic matter and biopolymers, and the topography with chernies and roots protecting the mangrove, calmer areas are created with the deposition of material transported by wave action. Compared to global distributions, concentrations of aromatic compounds in Suruí Mangrove may be classified from moderate to high, showing that the studied area is highly impacted.

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

PubMed Central

Sabbioni, G

1993-01-01

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

Anaerobic Microbial Transformation of Aromatic Hydrocarbons and Mixtures of Aromatic Hydrocarbons and Halogenated Solvents.

DTIC Science & Technology

1992-08-25

High initial concentrations of these compounds may be toxic or inhibitory to the microflora, especially if the microorganisms have not been exposed to...these compounds before. Slow acclimation of the microflora to lower concentrations of these compounds , that occur at the outskirts of contamination...acceptors such as nitrate or sulfate may impair the capability of the microorganisms to degrade these compounds , although anaerobic respiration -- in theory

Natural mediators in the oxidation of polycyclic aromatic hydrocarbons by laccase mediator systems

DOE Office of Scientific and Technical Information (OSTI.GOV)

Johannes, C.; Majcherczyk, A.

2000-02-01

The oxidation of polycyclic aromatic compounds was studied in systems consisting of laccase from Trametes versicolor and so-called mediator compounds. The enzymatic oxidation of acenaphthene, acenaphthylene, anthracene, and fluorene was mediated by various laccase substrates (phenols and aromatic amines) or compounds produced and secreted by white rot fungi. The best natural mediators, such as phenol, aniline, 4-hydroxybenzoic acid, and 4-hydroxybenzyl alcohol were as efficient as the previously described synthetic compounds ABTS [2,2{prime}-azino-bis-(3-ethylbenzothiazoline-6-sulfonic acid)] and 1-hydroxybenzotriazole. The oxidation efficiency increased proportionally with the redox potentials of the phenolic mediators up to a maximum value of 0.9 V and decreased thereafter withmore » redox potentials exceeding this value. Natural compounds such as methionine, cysteine, and reduced glutathione, containing sulfhydryl groups, were also active as mediator compounds.« less

Leaching of styrene and other aromatic compounds in drinking water from PS bottles.

PubMed

Ahmad, Maqbool; Bajahlan, Ahmad S

2007-01-01

Bottled water may not be safer, or healthier, than tap water. The present studies have proved that styrene and some other aromatic compounds leach continuously from polystyrene (PS) bottles used locally for packaging. Water sapmles in contact with PS were extracted by a preconcentration technique called as "purge and trap" and analysed by gas chromatograph-mass spectrometer (GC/MS). Eleven aromatic compounds were identified in these studies. Maximum concentration of styrene in PS bottles was 29.5 microg/L. Apart from styrene, ethyl benzene, toluene and benzene were also quantified but their concentrations were much less than WHO guide line values. All other compounds were in traces. Quality of plastic and storage time were the major factor in leaching of styrene. Concentration of styrene was increased to 69.53 microg/L after one-year storage. In Styrofoam and PS cups studies, hot water was found to be contaminated with styrene and other aromatic compounds. It was observed that temperature played a major role in the leaching of styrene monomer from Styrofoam cups. Paper cups were found to be safe for hot drinks.

Investigation on modes of toxic action to rats based on aliphatic and aromatic compounds and comparison with fish toxicity based on exposure routes.

PubMed

He, Jia; Li, Jin J; Wen, Yang; Tai, Hong W; Yu, Yang; Qin, Wei C; Su, Li M; Zhao, Yuan H

2015-06-01

The modes of toxic action (MOAs) play an important role in the assessment of the ecotoxicity of organic pollutants. However, few studies have been reported on the MOAs in rat toxicity. In this paper, the toxic contributions of functional groups in 1255 aromatic compounds were calculated from regression and were then compared with the toxic contributions in aliphatic compounds. The results show that some functional groups have same toxic contributions both in aromatic and aliphatic compounds, but some have not. To investigate the MOAs in rat toxicity, the distribution of toxic ratio (TR) was examined for well-known baseline and less inert compounds and thresholds of log TR=0.3 and 0.5 were used to classify baseline, less inert and reactive compounds. The results showed that some compounds identified as baseline compounds in fish toxicity were also classified as baseline compounds in rat toxicity. Except for phenols and anilines which were identified as less inert compounds in fish toxicity, aromatic compounds with functional groups such as ether, nitrile, nitrophenol, isocyanatoe and chloro were identified as less inert chemicals in rat toxicity. Reactive compounds identified in fish toxicity exhibit greater toxicity to rats. These compounds can undergo nucleophilic substitution, acylation and Schiff base formation with biological macromolecules. The critical body residues (CBRs) calculated from absorption and bioconcentration show that log 1/CBRs in rat toxicity are not equal to that in fish for some compounds. It suggests that the exposure route can affect the identification of MOAs between these two species for these compounds. Copyright © 2015 Elsevier Ltd. All rights reserved.

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.

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. Copyright © 2015 Elsevier B.V. All rights reserved.

Effects of organic wastes on water quality from processing of oil shale from the Green River Formation, Colorado, Utah, and Wyoming

USGS Publications Warehouse

Leenheer, J.A.; Noyes, T.I.

1986-01-01

A series of investigations were conducted during a 6-year research project to determine the nature and effects of organic wastes from processing of Green River Formation oil shale on water quality. Fifty percent of the organic compounds in two retort wastewaters were identified as various aromatic amines, mono- and dicarboxylic acids phenols, amides, alcohols, ketones, nitriles, and hydroxypyridines. Spent shales with carbonaceous coatings were found to have good sorbent properties for organic constituents of retort wastewaters. However, soils sampled adjacent to an in situ retort had only fair sorbent properties for organic constituents or retort wastewater, and application of retort wastewater caused disruption of soil structure characteristics and extracted soil organic matter constituents. Microbiological degradation of organic solutes in retort wastewaters was found to occur preferentially in hydrocarbons and fatty acid groups of compounds. Aromatic amines did not degrade and they inhibited bacterial growth where their concentrations were significant. Ammonia, aromatic amines, and thiocyanate persisted in groundwater contaminated by in situ oil shale retorting, but thiosulfate was quantitatively degraded one year after the burn. Thiocyanate was found to be the best conservative tracer for retort water discharged into groundwater. Natural organic solutes, isolated from groundwater in contact with Green River Formation oil shale and from the White River near Rangely, Colorado, were readily distinguished from organic constituents in retort wastewaters by molecular weight and chemical characteristic differences. (USGS)

Watershed-based sources of polycyclic aromatic hydrocarbons in urban storm water.

PubMed

Stein, Eric D; Tiefenthaler, Liesl L; Schiff, Kenneth

2006-02-01

Polycyclic aromatic hydrocarbons (PAHs) are carcinogenic and mutagenic compounds, ubiquitous in the air and water of urban environments, and have been shown to accumulate in coastal estuarine and marine sediments. Although previous studies have documented concentrations and loads of PAHs in urban runoff, little is known about the sources and temporal patterns of PAH loading from storm water. This study characterized the sources and temporal patterns of PAHs in urban storm water by analyzing PAH concentrations and loads from a range of homogeneous land use sites and in-river mass emission sites throughout the greater Los Angeles, California, USA, region. Samples were collected at 30- to 60-min intervals over the course of a storm during multiple storm events over a four-year period in order to investigate PAH sources and inter- and intrastorm patterns in loading. Polycyclic aromatic hydrocarbon storm fluxes ranged from 1.3 g/km2 for the largely undeveloped Arroyo Sequit watershed to 223.7 g/km2 for the highly urbanized Verdugo Wash watershed, with average storm fluxes being 46 times higher in developed versus undeveloped watersheds. Early-season storms repeatedly produced substantially higher loads than comparably sized late-season storms. Within individual storms, PAHs exhibited a moderate first flush with between 30 and 60% of the total PAH load being discharged in the first 20% of the storm volume. The relative distribution of individual PAHs demonstrated a consistent predominance of high-molecular-weight compounds indicative of pyrogenic sources.

Some aromatic hydrazone derivatives as inhibitors for the corrosion of C-steel in phosphoric acid solution.

PubMed

Fouda, Abd El-Aziz S; Al-Sarawy, Ahmed A; Radwan, Mohamed S

2006-01-01

The effect of furfural benzoylhydrazone and its derivatives (I-VII) as corrosion inhibitors for C-steel in 1M phosphoric acid solution has been studied by weight-loss and galvanostatic polarization techniques. A significant decrease in the corrosion rate of C-steel was observed in the presence of the investigated inhibitors. This study revealed that, the inhibition efficiency increases with increasing the inhibitor concentration, and the addition of iodide ions enhances it to a considerable extent. The effect of temperature on the inhibition efficiency of these compounds was studied using weight-loss method. Activation energy (E(a)*) and other thermodynamic parameters for the corrosion process were calculated and discussed. The galvanostatic polarization data indicated that, the inhibitors were of mixed-type, but the cathode is more polarized than the anode. The adsorption of these compounds on C-steel surface has been found to obey Frumkin's adsorption isotherm. The mechanism of inhibition was discussed in the light of the chemical structure of the undertaken inhibitors.

Biodegradation studies of selected hydrocarbons from diesel oil.

PubMed

Sepic, E; Trier, C; Leskovsek, H

1996-10-01

In-vitro biodegradation of aliphatic and aromatic hydrocarbons present in diesel oil by Pseudomonas fluorescens, Texaco was studied in an aqueous medium. Small aliquots of diesel oil and its aromatic fraction were incubated aerobically for periods of up to seven months and analysed by GC-MS. Biotic losses proved to be greater for aliphatic than aromatic compounds. Most biodegradation occurred within the first 20 d of incubation. The most rapid biodegradation, up to 65% in 8 d, was observed for n-alkanes (C14-C18). The same compounds were also shown to be less affected by abiotic losses. Biodegradation of n-alkanes from diesel oil and diesel oil itself showed first order kinetics for the initial incubation period. Aromatic compounds proved to be resistant to biodegradation and only phenanthrene had been degraded (30%) within 6 months.

In Vitro Enzymatic Depolymerization of Lignin with Release of Syringyl, Guaiacyl, and Tricin Units

PubMed Central

Gall, Daniel L.; Kontur, Wayne S.; Lan, Wu; Kim, Hoon; Li, Yanding; Ralph, John

2017-01-01

ABSTRACT New environmentally sound technologies are needed to derive valuable compounds from renewable resources. Lignin, an abundant polymer in terrestrial plants comprised predominantly of guaiacyl and syringyl monoaromatic phenylpropanoid units, is a potential natural source of aromatic compounds. In addition, the plant secondary metabolite tricin is a recently discovered and moderately abundant flavonoid in grasses. The most prevalent interunit linkage between guaiacyl, syringyl, and tricin units is the β-ether linkage. Previous studies have shown that bacterial β-etherase pathway enzymes catalyze glutathione-dependent cleavage of β-ether bonds in dimeric β-ether lignin model compounds. To date, however, it remains unclear whether the known β-etherase enzymes are active on lignin polymers. Here we report on enzymes that catalyze β-ether cleavage from bona fide lignin, under conditions that recycle the cosubstrates NAD+ and glutathione. Guaiacyl, syringyl, and tricin derivatives were identified as reaction products when different model compounds or lignin fractions were used as substrates. These results demonstrate an in vitro enzymatic system that can recycle cosubstrates while releasing aromatic monomers from model compounds as well as natural and engineered lignin oligomers. These findings can improve the ability to produce valuable aromatic compounds from a renewable resource like lignin. IMPORTANCE Many bacteria are predicted to contain enzymes that could convert renewable carbon sources into substitutes for compounds that are derived from petroleum. The β-etherase pathway present in sphingomonad bacteria could cleave the abundant β–O–4-aryl ether bonds in plant lignin, releasing a biobased source of aromatic compounds for the chemical industry. However, the activity of these enzymes on the complex aromatic oligomers found in plant lignin is unknown. Here we demonstrate biodegradation of lignin polymers using a minimal set of β-etherase pathway enzymes, the ability to recycle needed cofactors (glutathione and NAD+) in vitro, and the release of guaiacyl, syringyl, and tricin as depolymerized products from lignin. These observations provide critical evidence for the use and future optimization of these bacterial β-etherase pathway enzymes for industrial-level biotechnological applications designed to derive high-value monomeric aromatic compounds from lignin. PMID:29180366

Inhibition of hydroxyl radical reaction with aromatics by dissolved natural organic matter

USGS Publications Warehouse

Lindsey, M.E.; Tarr, M.A.

2000-01-01

Reaction of aromatic compounds with hydroxyl radical is inhibited by dissolved natural organic matter (NOM). The degree of inhibition is significantly greater than that expected based on a simple model in which aromatic compound molecules bound to NOM are considered to be unreactive. In this study, hydroxyl radical was produced at steady-state concentrations using Fenton chemistry (H2O2 + Fe2+ ??? Fe3+ + HO- + HO??). Suwannee River fulvic acid and humic acid were used as NOM. The most likely mechanism for the observed inhibition is that hydroxyl radical formation occurs in microenvironmental sites remote from the aromatic compounds. In addition to changes in kinetics, pyrene hydroxyl radical reaction also exhibited a mechanistic change in the presence of fulvic acid. The mechanism changed from a reaction that was apparently firstorder in pyrene to one that was apparently secondorder in pyrene, indicating that pyrene self-reaction may have become the dominant mechanism in the presence of fulvic acid. Dissolved NOM causes significant changes in the rate and mechanism of hydroxyl radical degradation of aromatic compounds. Consequently, literature rate constants measured in pure water will not be useful for predicting the degradation of pollutants in environmental systems. The kinetic and mechanistic information in this study will be useful for developing improved degradation methods involving Fenton chemistry.Reaction of aromatic compounds with hydroxyl radical is inhibited by dissolved natural organic matter (NOM). The degree of inhibition is significantly greater than that expected based on a simple model in which aromatic compounds molecules bounds to NOM are considered to be unreactive. In this study, hydroxyl radical was produced at steady-state concentrations using Fenton chemistry (H2O2 + Fe2+ ??? Fe3+ + HO- + HO??). Suwannee River fulvic acid and humic acid were used as NOM. The most likely mechanisms for the observed inhibition is that hydroxyl radical formation occurs in microenvironmental sites remote from the aromatic compounds. In addition to changes in kinetics, pyrene hydroxyl radical reaction also exhibited a mechanistic change in the presence of fulvic acid. The mechanism changed from a reaction that was apparently first-order in pyrene to one that was apparently second-order in pyrene, indicating that pyrene self-reaction may have become the dominant mechanism in the presence of fulvic acid. Dissolved NOM causes significant changes in the rate and mechanism of hydroxyl radical degradation of aromatic compounds. Consequently, literature rate constants measured in pure water will not be useful for predicting the degradation of pollutants in environmental systems. The kinetic and mechanistic information in this study will be useful for developing improved degradation methods involving Fenton chemistry.

EFFECT OF IRRADIANCE SPECTRA ON THE PHOTOINDUCED TOXICITY OF THREE POLYCYCLIC AROMATIC HYDROCARBONS

EPA Science Inventory

Photoinduced toxicity of polycyclic aromatic hydrocarbons (PAHs) is dependent on the concentration of compounds present and the dose of light received. Of the light present, only those wavelengths absorbed by the compound have the potential to initiate the photochemical events un...

THE EFFECT OF IRRADIANCE SPECTRA ON THE PHOTOACTIVATED TOXICITY OF THREE POLYCYCLIC AROMATIC HYDROCARBONS

EPA Science Inventory

Photoinduced toxicity of polycyclic aromatic hydrocarbons (PAHs) is dependent on the concentration of compounds present and the dose of light recieved. Of the light present, only those wavelengths absorbed by the compound have the potential to initiate the photochemical events un...

Polycyclic aromatic hydrocarbons and volatile organic compounds in biochar and biochar-amended soil: A review

USDA-ARS?s Scientific Manuscript database

Residual pollutants including polycyclic aromatic hydrocarbons (PAHs), volatile organic compounds (VOCs), and carbon(aceous) nanoparticles are inevitably generated during the pyrolysis of waste biomass, and remain on the solid co-product called biochar. Such pollutants could have adverse effects on ...

Ionization of EPA Contaminants in Direct and Dopant-Assisted Atmospheric Pressure Photoionization and Atmospheric Pressure Laser Ionization

NASA Astrophysics Data System (ADS)

Kauppila, Tiina J.; Kersten, Hendrik; Benter, Thorsten

2015-06-01

Seventy-seven EPA priority environmental pollutants were analyzed using gas chromatography-mass spectrometry (GC-MS) equipped with an optimized atmospheric pressure photoionization (APPI) and an atmospheric pressure laser ionization (APLI) interface with and without dopants. The analyzed compounds included e.g., polycyclic aromatic hydrocarbons (PAHs), nitro compounds, halogenated compounds, aromatic compounds with phenolic, acidic, alcohol, and amino groups, phthalate and adipatic esters, and aliphatic ethers. Toluene, anisole, chlorobenzene, and acetone were tested as dopants. The widest range of analytes was ionized using direct APPI (66/77 compounds). The introduction of dopants decreased the amount of compounds ionized in APPI (e.g., 54/77 with toluene), but in many cases the ionization efficiency increased. While in direct APPI the formation of molecular ions via photoionization was the main ionization reaction, dopant-assisted (DA) APPI promoted ionization reactions, such as charge exchange and proton transfer. Direct APLI ionized a much smaller amount of compounds than APPI (41/77 compounds), showing selectivity towards compounds with low ionization energies (IEs) and long-lived resonantly excited intermediate states. DA-APLI, however, was able to ionize a higher amount of compounds (e.g. 51/77 with toluene), as the ionization took place entirely through dopant-assisted ion/molecule reactions similar to those in DA-APPI. Best ionization efficiency in APPI and APLI (both direct and DA) was obtained for PAHs and aromatics with O- and N-functionalities, whereas nitro compounds and aliphatic ethers were the most difficult to ionize. Halogenated aromatics and esters were (mainly) ionized in APPI, but not in APLI.

Self-Assembly and Nanostructures in Organogels Based on a Bolaform Cholesteryl Imide Compound with Conjugated Aromatic Spacer

PubMed Central

Jiao, Ti-Feng; Gao, Feng-Qing; Shen, Xi-Hai; Zhang, Qing-Rui; Zhang, Xian-Fu; Zhou, Jing-Xin; Gao, Fa-Ming

2013-01-01

The self-assembly of small functional molecules into supramolecular structures is a powerful approach toward the development of new nanoscale materials and devices. As a class of self-assembled materials, low weight molecular organic gelators, organized in special nanoarchitectures through specific non-covalent interactions, has become one of the hot topics in soft matter research due to their scientific values and many potential applications. Here, a bolaform cholesteryl imide compound with conjugated aromatic spacer was designed and synthesized. The gelation behaviors in 23 solvents were investigated as efficient low-molecular-mass organic gelator. The experimental results indicated that the morphologies and assembly modes of as-formed organogels can be regulated by changing the kinds of organic solvents. Scanning electron microscopy and atomic force microscopy observations revealed that the gelator molecule self-assemble into different aggregates, from wrinkle and belt to fiber with the change of solvents. Spectral studies indicated that there existed different H-bond formations between imide groups and assembly modes. Finally, some rational assembly modes in organogels were proposed and discussed. The present work may give some insight to the design and character of new organogelators and soft materials with special structures. PMID:28788428

Selective Sorbents For Purification Of Hydrocarbons

DOEpatents

Yang, Ralph T.; Yang, Frances H.; Takahashi, Akira; Hernandez-Maldonado, Arturo J.

2006-04-18

A method for removing thiophene and thiophene compounds from liquid fuel includes contacting the liquid fuel with an adsorbent which preferentially adsorbs the thiophene and thiophene compounds. The adsorption takes place at a selected temperature and pressure, thereby producing a non-adsorbed component and a thiophene/thiophene compound-rich adsorbed component. The adsorbent includes either a metal or a metal ion that is adapted to form p-complexation bonds with the thiophene and/or thiophene compounds, and the preferential adsorption occurs by p-complexation. A further method includes selective removal of aromatic compounds from a mixture of aromatic and aliphatic compounds.

Selective sorbents for purification of hydrocarbons

DOEpatents

Yang, Ralph T.; Hernandez-Maldonado, Arturo J.; Yang, Frances H.; Takahashi, Akira

2006-08-22

A method for removing thiophene and thiophene compounds from liquid fuel includes contacting the liquid fuel with an adsorbent which preferentially adsorbs the thiophene and thiophene compounds. The adsorption takes place at a selected temperature and pressure, thereby producing a non-adsorbed component and a thiophene/thiophene compound-rich adsorbed component. The adsorbent includes either a metal or a metal cation that is adapted to form .pi.-complexation bonds with the thiophene and/or thiophene compounds, and the preferential adsorption occurs by .pi.-complexation. A further method includes selective removal of aromatic compounds from a mixture of aromatic and aliphatic compounds.

Selective sorbents for purification of hydrocarbons

DOEpatents

Yang, Ralph T.; Yang, Frances H.; Takahashi, Akira; Hernandez-Maldonado, Arturo J.

2006-05-30

A method for removing thiophene and thiophene compounds from liquid fuel includes contacting the liquid fuel with an adsorbent which preferentially adsorbs the thiophene and thiophene compounds. The adsorption takes place at a selected temperature and pressure, thereby producing a non-adsorbed component and a thiophene/thiophene compound-rich adsorbed component. The adsorbent includes either a metal or a metal cation that is adapted to form .pi.-complexation bonds with the thiophene and/or thiophene compounds, and the preferential adsorption occurs by .pi.-complexation. A further method includes selective removal of aromatic compounds from a mixture of aromatic and aliphatic compounds.

Selective sorbents for purification of hydrocartons

DOEpatents

Yang, Ralph T.; Yang, Frances H.; Takahashi, Akira; Hermandez-Maldonado, Arturo J.

2006-12-12

A method for removing thiophene and thiophene compounds from liquid fuel includes contacting the liquid fuel with an adsorbent which preferentially adsorbs the thiophene and thiophene compounds. The adsorption takes place at a selected temperature and pressure, thereby producing a non-adsorbed component and a thiophene/thiophene compound-rich adsorbed component. The adsorbent includes either a metal or a metal ion that is adapted to form .pi.-complexation bonds with the thiophene and/or thiophene compounds, and the preferential adsorption occurs by .pi.-complexation. A further method includes selective removal of aromatic compounds from a mixture of aromatic and aliphatic compounds.

Catalysts and process for liquid hydrocarbon fuel production

DOEpatents

White, Mark G; Liu, Shetian

2014-12-09

The present invention provides a novel process and system in which a mixture of carbon monoxide and hydrogen synthesis gas, or syngas, is converted into hydrocarbon mixtures composed of high quality gasoline components, aromatic compounds, and lower molecular weight gaseous olefins in one reactor or step. The invention utilizes a novel molybdenum-zeolite catalyst in high pressure hydrogen for conversion, as well as a novel rhenium-zeolite catalyst in place of the molybdenum-zeolite catalyst, and provides for use of the novel catalysts in the process and system of the invention.

Chemistry and properties of poly(arylene ether 1,3,4-oxadiazole)s and poly(arylene ether 1,2,4-triazole)s

NASA Technical Reports Server (NTRS)

Connell, J. W.; Hergenrother, P. M.; Wolf, P.

1992-01-01

Poly(arylene ether)s containing l,3,4-oxadiazole and 1,2,4-triazole units were prepared by the aromatic nucleophilic displacement reaction of bisphenol oxadiazole and bisphenol triazole compounds with activated aromatic dihalides. The polymers exhibited glass transition temperatures (Tg) ranging from 182 to 242 C, and several polymers exhibited melting transitions (Tm) ranging from 265 to 390 C. Inherent viscosities ranged from 1.02 to 3.40 dl/g, indicating relatively high molecular weights. Thin films exhibited tensile strengths, moduli, and elongations at 23 C of 90-110 MPa, 2.7-3.6 GPa, and 4-7 percent, respectively. Titanium-to-titanium tensile shear specimens of a poly(arylene ether 1,3,4-oxadiazole) exhibited tensile shear strengths at 23 and 150 C of 22.1 and 17.9 MPa, respectively.

Distribution and Sources of Petroleum Hydrocarbons in Recent Sediments of the Imo River, SE Nigeria.

PubMed

Oyo-Ita, Inyang O; Oyo-Ita, Orok E; Dosunmu, Miranda I; Domínguez, Carmen; Bayona, Josep M; Albaigés, Joan

2016-02-01

The distribution of aliphatic and aromatic hydrocarbons in surface sediments of the lower course of the Imo River (Nigeria) was investigated to determine the sources and fate of these compounds. The aliphatic fraction is characterized by a widespread contribution of highly weathered/biodegraded hydrocarbon residues (reflected in the absence of prominent n-alkane peaks coupled with the presence of 17α(H),21β(H)-25-norhopane, an indicator of heavy hydrocarbon biodegradation) of Nigerian crude oils (confirmed by the occurrence of 18α(H)-oleanane, a compound characteristic of oils of deltaic origin). The concentrations of polycyclic aromatic hydrocarbons (PAHs) ranging from 48 to 117 ng/g dry weight (dw; ∑13PAHs) indicate a moderate pollution, possibly lowered by the sandy lithology and low organic carbon (OC) content of the sediments. Concentrations slightly decrease towards the estuary of the river, probably due to the fact that these stations are affected by tidal flushing of pollutants adsorbed on sediment particles and carried away by occasional storm to the Atlantic Ocean. A number of PAH ratios, including parent/alkylated and isomeric compounds, indicates a predominance of petrogenic sources, with a low contribution of pyrolytic inputs, particularly of fossil fuel combustion. On the basis of OC/ON (>10) and Per/ΣPAHpenta- (>10) values, a diagenetic terrigenous OC was proposed as a source of perylene to the river.

Investigation of Source of Irritant Gas Produced by PATRIOT Missile System Air Conditioners

DTIC Science & Technology

1986-03-31

is the mass fragment CF3 . It is a common fragment of perfluorinated hydrocarbons, and is found to be present in most of the compounds detected by...used would allow detection of the target par3meters acrolein, aromatics, a broad range of organic compounds ,. formaldehyde, and hydrogen cyanide...organic compounds were observed. Thus, aromatic organic compounds were not produced by or from any of the four new units tested. 4 1CZ 3) With the

DNA tests for strawberry: mesifurane "sherry" aroma - FaOMT-SI/NO

USDA-ARS?s Scientific Manuscript database

The amazing flavor and texture in strawberries is caused by a complex balance of numerous sugars and aromatic compounds. One of the most important aromatic compounds contributing to the flavor we have come to love in strawberries is mesifurane. Mesifurane produces a sweet sherry-like aroma and incre...

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...

Photochemical reactions of aromatic compounds and the concept of the photon as a traceless reagent.

PubMed

Hoffmann, Norbert

2012-11-01

Electronic excitation significantly changes the reactivity of chemical compounds. Compared to ground state reactions, photochemical reactions considerably enlarge the application spectrum of a particular functional group in organic synthesis. Multistep syntheses may be simplified and perspectives for target oriented synthesis (TOS) and diversity oriented synthesis (DOS) are developed. New compound families become available or may be obtained more easily. In contrast to common chemical reagents, photons don't generate side products resulting from the transformation of a chemical reagent. Therefore, they are considered as a traceless reagent. Consequently, photochemical reactions play a central role in the methodology of sustainable chemistry. This aspect has been recognized since the beginning of the 20th century. As with many other photochemical transformations, photochemical reactions of aromatic, benzene-like compounds illustrate well the advantages in this context. Photochemical cycloadditions of aromatic compounds have been investigated for a long time. Currently, they are applied in various fields of organic synthesis. They are also studied in supramolecular structures. The phenomena of reactivity and stereoselectivity are investigated. During recent years, photochemical electron transfer mediated reactions are particularly focused. Such transformations have likewise been performed with aromatic compounds. Reactivity and selectivity as well as application to organic synthesis are studied.

Removal of crude oil polycyclic aromatic hydrocarbons via organoclay-microbe-oil interactions.

PubMed

Ugochukwu, Uzochukwu C; Fialips, Claire I

2017-05-01

Clay minerals are quite vital in biogeochemical processes but the effect of organo-clays in the microbial degradation of crude oil polycyclic aromatic hydrocarbons is not well understood. The role of organo-saponite and organo-montmorillonite in comparison with the unmodified clays in crude oil polycyclic aromatic hydrocarbons (PAHs) removal via adsorption and biodegradation was studied by carrying out microcosm experiments in aqueous clay/oil systems with a hydrocarbon degrading microbial community that is predominantly alcanivorax spp. Montmorillonite and saponite samples were treated with didecyldimethylammonium bromide to produce organo-montmorillonite and organo-saponite used in this study. Obtained results indicate that clays with high cation exchange capacity (CEC) such as montmorillonite produced organo-clay (organomontmorillonite) that was not stimulatory to biodegradation of crude oil polycyclic aromatic compounds, especially the low molecular weight (LMW) ones, such as dimethylnaphthalenes. It is suggested that interaction between the organic phase of the organo-clay and the crude oil PAHs which is hydrophobic in nature must have reduced the availability of the polycyclic aromatic hydrocarbons for biodegradation. Organo-saponite did not enhance the microbial degradation of dimethylnaphthalenes but enhanced the biodegradation of some other PAHs such as phenanthrene. The unmodified montmorillonite enhanced the microbial degradation of the PAHs and is most likely to have done so as a result of its high surface area that allows the accumulation of microbes and nutrients enhancing their contact. Copyright © 2017 Elsevier Ltd. All rights reserved.

Photooxidation products of polycyclic aromatic compounds containing sulfur.

PubMed

Bobinger, Stefan; Andersson, Jan T

2009-11-01

Photooxidation of crude oil components is an important process that removes pollutants from the environment. Polycyclic aromatic compounds (PACs) are known to be toxic to many life forms, but little is known about their photooxidation products in the aqueous phase. We here identify a large number of photoproducts from 11 benzothiophenes, a polycyclic aromatic sulfur heterocycle that is a major representative of PACs in crude oil. The investigated compounds contain two to four methyl groups and an ethyl or an n-octyl group. In water, the products arise through oxidation of alkyl side chains to aldehydes and carboxylic acids or through an opening in one of the aromatic rings. The product analysis was performed using gas chromatography with mass spectrometric or atomic emission detection. The main product is always a sulfobenzoic acid, which strongly lowers the pH of the solution. With long alkyl substituents, surfactants are formed, which may possess solubilizing properties in water. The larger the number of alkyl groups, the faster is the photooxidation. Several of the identified acidic compounds were also found when whole crude oil was photooxidized, showing that simulation with individual compounds reflects the situation in whole crude.

From Clothing to Laundry Water: Investigating the Fate of Phthalates, Brominated Flame Retardants, and Organophosphate Esters.

PubMed

Saini, Amandeep; Thaysen, Clara; Jantunen, Liisa; McQueen, Rachel H; Diamond, Miriam L

2016-09-06

The accumulation of phthalate esters, brominated flame retardants (BFRs) and organophosphate esters (OPEs) by clothing from indoor air and transfer via laundering to outdoors were investigated. Over 30 days cotton and polyester fabrics accumulated 3475 and 1950 ng/dm(2) ∑5phthalates, 65 and 78 ng/dm(2) ∑10BFRs, and 1200 and 310 ng/dm(2) ∑8OPEs, respectively. Planar surface area concentrations of OPEs and low molecular weight phthalates were significantly greater in cotton than polyester and similar for BFRs and high molecular weight phthalates. This difference was significantly and inversely correlated with KOW, suggesting greater sorption of polar compounds to polar cotton. Chemical release from cotton and polyester to laundry water was >80% of aliphatic OPEs (log KOW < 4), < 50% of OPEs with an aromatic structure, 50-100% of low molecular weight phthalates (log KOW 4-6), and < detection-35% of higher molecular weight phthalates (log KOW > 8) and BFRs (log KOW > 6). These results support the hypothesis that clothing acts an efficient conveyer of soluble semivolatile organic compounds (SVOCs) from indoors to outdoors through accumulation from air and then release during laundering. Clothes drying could as well contribute to the release of chemicals emitted by electric dryers. The results also have implications for dermal exposure.

Selective Oxidation of Lignin Model Compounds.

PubMed

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

2018-05-02

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

Activity of selected aromatic amino acids in biological systems.

PubMed

Krzyściak, Wirginia

2011-01-01

Besides the structural function in proteins, aromatic amino acids are precursors of many important biological compounds essential for normal functioning of the human organism. Many of these compounds may be used as markers for identification of specific pathological states. Comprehensive knowledge about the metabolism of aromatic amino acids and mechanisms of action of their metabolites made it possible to develop effective treatments for many disorders. However, it should not be forgotten that in some pathological conditions, these compounds could not only be involved in the pathogenesis of many disease entities but could also be used as an important tool in prediction of many diseases. This paper contains a review of published literature on aromatic amino acids in the context of physiological processes of the human body and chosen social disorders, such as cancers; psychiatric disorders: depression, anxiety states, schizophrenia, bipolar affective disorders; neurodegenerative, and cardiovascular diseases; chronic kidney insufficiency or diabetes.

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).

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

DOE Office of Scientific and Technical Information (OSTI.GOV)

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. Besidesmore » 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.« less

Studies on in vitro biostability and blood compatibility of polyurethane potting compound based on aromatic polymeric MDI for extracorporeal devices.

PubMed

Hridya, V K; Jayabalan, M

2009-12-01

Polyurethane potting compound based on aromatic isocyanurate of polymeric MDI, poly propylene glycol (PPG400) and trimethylol propane (TMP) has significant favourable properties, good pot life and setting characteristics. The cured potting compound of this formulation has appreciable thermal stability and mechanical properties. In vitro biostability of cured potting compound has been found to be excellent without any significant degradation in simulated physiological media and chemical environment. Studies on blood-material interaction and cytotoxicity reveal in vitro blood compatibility and compatibility with cells of this potting compound.

Structure-activity relationship and docking studies of thiazolidinedione-type compounds with monoamine oxidase B.

PubMed

Carroll, Richard T; Dluzen, Dean E; Stinnett, Hilary; Awale, Prabha S; Funk, Max O; Geldenhuys, Werner J

2011-08-15

The neuroprotective activity of pioglitazone and rosiglitazone in the MPTP parkinsonian mouse prompted us to evaluate a set of thiazolidinedione (TZD) type compounds for monoamine oxidase A and B inhibition activity. These compounds were able to inhibit MAO-B over several log units of magnitude (82 nM to 600 μM). Initial structure-activity relationship studies identified key areas to modify the aromatic substituted TZD compounds. Primarily, substitutions on the aromatic group and the TZD nitrogen were key areas where activity was enhanced within this group of compounds. Copyright © 2011 Elsevier Ltd. All rights reserved.

Novel chemoselective hydrogenation of aromatic nitro compounds over ferric hydroxide supported nanocluster gold in the presence of CO and H2O.

PubMed

Liu, Lequan; Qiao, Botao; Chen, Zhengjian; Zhang, Juan; Deng, Youquan

2009-02-14

Chemoselective hydrogenation of aromatic nitro compounds were first efficiently achieved over Au/Fe(OH)(x) at 100-120 degrees C for 1.5-6 h (depending on different substrates) in the presence of CO and H(2)O.

BINDING OF CARCINOGENS TO DNA AND COVALENT ADDUCTS DNA DAMAGE - PAH, AROMATIC AMINES, NITRO-AROMATIC COMPOUNDS, AND HALOGENATED COMPOUNDS

EPA Science Inventory

DNA adducts are the covalent addition products resulting from binding of reactive chemical species to DNA bases. The cancer initiating role of DNA adducts is well-established, and is clearly reflected in the high cancer incidence observed in individuals with deficiencies in any o...

Theoretical investigation of the interaction between aromatic sulfur compounds and [BMIM](+)[FeCl4](-) ionic liquid in desulfurization: A novel charge transfer mechanism.

PubMed

Li, Hongping; Zhu, Wenshuai; Chang, Yonghui; Jiang, Wei; Zhang, Ming; Yin, Sheng; Xia, Jiexiang; Li, Huaming

2015-06-01

In this work, interaction nature between a group of aromatic sulfur compounds and [BMIM](+)[FeCl4](-) have been investigated by density functional theory (DFT). A coordination structure is found to be critical to the mechanism of extractive desulfurization. Interaction energy and extractive selectivity follow the order: thiophene (TH)

Influence of silicon defects on the adsorption of thiophene-like compounds on polycyclic aromatic hydrocarbons: a theoretical study using thiophene + coronene as the simplest model.

PubMed

Galano, Annia

2007-03-08

Physisorption and chemisorption processes of thiophene on coronene and 2Si-coronene have been studied using density functional theory and MP2 methods. These systems have been chosen as the simplest models to describe the adsorption of thiophene-like compounds on polycyclic aromatic hydrocarbons (PAHs). The calculated data suggest that the presence of silicon atoms in PAHs could favor their interaction with thiophene and similar compounds. Small stabilization energies have been found for several physisorbed complexes. The thiophene chemisorption on coronene seems very unlikely to occur, while that on 2Si-coronene leads to addition products which are very stable, with respect to the isolated reactants. These chemisorption processes were found to be exoergic (DeltaG < 0) in the gas phase and in the nonpolar liquid phase. The results reported in this work suggest that silicon defects on extended polycyclic aromatic hydrocarbons, such as graphite, soot, and large-diameter carbon nanotubes, could make them useful in the removal processes of aromatic sulfur compounds from oil hydrocarbons.

Substituent effect on the oxidation of phenols and aromatic amines by horseradish peroxidase compound I.

PubMed

Job, D; Dunford, H B

1976-07-15

A stopped-flow kinetic study shows that the reduction rate of horseradish peroxidase compound I by phenols and aromatic amines is greatly dependent upon the substituent effect on the benzene ring. Morever it has been possible to relate the reduction rate constants of monosubstituted substrates by a linear free-energy relationship (Hammett equation). The correlation of log (rate constants) with sigma values (Hammett equation) and the absence of correlation with sigma+ values (Okamoto-Brown equation) can be explained by a mechanism of aromatic substrate oxidations, in which the substrate gives an electron to the enzyme compound I and simultaneously loses a proton. The analogy which has been made with oxidation potentials of phenols or anilines strengthens the view that the reaction is only dependent on the relative ease of oxidation of the substrate. The rate constant obtained for p-aminophenol indicates that a value of 2.3 X 10(8) M-1 S-1 probably approaches the diffusion-controlled limit for a bimolecular reaction involving compound I and an aromatic substrate.

Shape-selective adsorption of aromatic molecules from water by tetramethylammonium-smectite

USGS Publications Warehouse

Lee, J.; Mortland, M.M.; Boyd, S.A.; Chiou, C.T.

1989-01-01

The adsorption of aromatic compounds by smectite exchanged with tetramethylammonium (TMA) has been studied. Aromatic compounds adsorbed by TMA-smectite are assumed to adopt a tilted orientation in a face-to-face arrangment with the TMA tetrahedra. The sorptive characteristics of TMA-smectite were influenced strongly by the presence of water. The dry TMA-smectite showed little selectivity in the uptake of benzen, toluene and xylene. In the presence of water, TMA-smectite showed a high degree of selectivity based on molecular size/shape, resulting in high uptake of benzene and progressively lower uptake of larger aromatic molecules. This selectivity appeared to result from the shrinkage of interlamellar cavities by water.

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.

Presence of polycyclic aromatic hydrocarbons (PAHs) in apple in rural terrains from Mexico City.

PubMed

Salinas, Rutilio Ortiz; González, Gilberto Díaz; Bermudez, Beatriz Schettino; Tolentino, Rey Gutiérrez; Vega Y León, Salvador

2010-08-01

This paper describes PAH concentrations in apple crops that are growing in rural terrains in Mexico City. The concentrations of individual PAHs showed great variability, there being low and high molecular weight compounds in dry (high molecular weight for Tlahuac 7.06 microg/g and Milpa Alta 3.96 microg/g) and wet months (high molecular weight for Tlahuac 11.25 microg/g and Milpa Alta 12.05 microg/g). Some PAHs indicators and cross plot ratios Ant/(Ant + Phe) and Flu/(Flu + Pyr) define fossil fuels and vegetation combustion as the source of contamination over the cuticle of the apples. It is likely that deposition (dry and wet) is the principal source o f contamination over the apple surface. This study reveals the presence of PAHs in apples due to the high air contamination of Mexico City.

Remarkably selective iridium catalysts for the elaboration of aromatic C-H bonds.

PubMed

Cho, Jian-Yang; Tse, Man Kin; Holmes, Daniel; Maleczka, Robert E; Smith, Milton R

2002-01-11

Arylboron compounds have intriguing properties and are important building blocks for chemical synthesis. A family of Ir catalysts now enables the direct synthesis of arylboron compounds from aromatic hydrocarbons and boranes under "solventless" conditions. The Ir catalysts are highly selective for C-H activation and do not interfere with subsequent in situ transformations, including Pd-mediated cross-couplings with aryl halides. By virtue of their favorable activities and exceptional selectivities, these Ir catalysts impart the synthetic versatility of arylboron reagents to C-H bonds in aromatic and heteroaromatic hydrocarbons.

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...

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wear, Jr., John Edmund

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 naturallymore » 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.« less

Hydrogen bonded supra-molecular framework in inorganic-organic hybrid compounds: Syntheses, structures, and photoluminescent properties

NASA Astrophysics Data System (ADS)

Yan, Li; Liu, Wei; Li, Chuanbi; Wang, Yifei; Ma, Li; Dong, Qinqin

2013-03-01

Two novel compounds constructed from aromatic acid and N-Heterocyclic ligands have been synthesized by hydrothermal reaction: [Cd(mip)(1,8-NDC)(H2O)]2 (1) [mip = 2-(3-methoxyphenyl)-1H-imidazo[4,5-f][1,10]phenanthroline, 1,8-NDC = naphthalene-1,8-dicarboxylic acid] and Cd(mip)2(NTC)2 (2) [NTC = nicotinic acid]. Compounds 1 and 2 are characterized by elemental analysis, IR, single crystal X-ray diffraction and thermogravimetric analysis (TGA). Single-crystal X-ray investigation reveals that compounds 1-2 are 0 dimensional (0D) structures, and the existence of hydrogen bonds and π-π interactions lead the 0D to 2D novel framework. Hydrogen bonds and π-π interactions are powerful non-covalent intermolecular interactions for directing supra-molecular architectures. TG analysis shows clear courses of weight loss, which corresponds to the decomposition of different ligands. At room temperature, compound 1 exhibits emission at 449 nm upon excitation at 325 nm, and compound 2 shows a strong emission at 656 nm upon excitation at 350 nm. Fluorescent spectrum displays that compounds 1 and 2 are potential luminescent materials.

Enzymatic Specific Production and Chemical Functionalization of Phenylpropanone Platform Monomers from Lignin

PubMed Central

Hasegawa, Ryoichi; Kurosawa, Kanako; Maeda, Allyn H.; Koizumi, Toshio; Nishimura, Hiroshi; Okada, Hitomi; Qu, Chen; Saito, Kaori; Watanabe, Takashi; Hatada, Yuji

2016-01-01

Abstract Enzymatic catalysis is an ecofriendly strategy for the production of high‐value low‐molecular‐weight aromatic compounds from lignin. Although well‐definable aromatic monomers have been obtained from synthetic lignin‐model dimers, enzymatic‐selective synthesis of platform monomers from natural lignin has not been accomplished. In this study, we successfully achieved highly specific synthesis of aromatic monomers with a phenylpropane structure directly from natural lignin using a cascade reaction of β‐O‐4‐cleaving bacterial enzymes in one pot. Guaiacylhydroxylpropanone (GHP) and the GHP/syringylhydroxylpropanone (SHP) mixture are exclusive monomers from lignin isolated from softwood (Cryptomeria japonica) and hardwood (Eucalyptus globulus). The intermediate products in the enzymatic reactions show the capacity to accommodate highly heterologous substrates at the substrate‐binding sites of the enzymes. To demonstrate the applicability of GHP as a platform chemical for bio‐based industries, we chemically generate value‐added GHP derivatives for bio‐based polymers. Together with these chemical conversions for the valorization of lignin‐derived phenylpropanone monomers, the specific and enzymatic production of the monomers directly from natural lignin is expected to provide a new stream in “white biotechnology” for sustainable biorefineries. PMID:27878983

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 identification and characterization of aromatic and condensed aromatic compounds in WSOC [2]. We proposed threshold values of Xc≥ 2.5000 and Xc≥ 2.7143 as ambiguous minimum criteria for the presence of aromatic structure and condensed aromatic compounds, respectively. The advantage of employing this parameter is that Xc would have a constant value for each proposed core structure regardless the degree of alkylation, and thus visual representation and structural interpretations of the spectra become advantageous for characterizing and comparing complex samples. Diesel particulate matter (DPM) and two atmospheric aerosols collected in the industrial area affected by biomass burning events were used to study the applicability of the proposed criteria for the improved identification of aromatic and condensed aromatic structures in complex mixtures in the FT-ICR mass spectra. References [1] Koch.BP, Dittmar.T. From mass to structure: an aromaticity index for high-resolution mass data of natural organic matter. Rapid Commun. Mass Spectrom. 2006, 20, 926-932 [2] Yassine.MM, Harir.M, Dabek-Zlotorzynska.E, Schmitt-Kopplin.Ph. Structural characterization of organic aerosol using Fourier transform ion cyclotron resonance mass spectrometry: Aromaticity equivalent approach. Rapid Commun. Mass Spectrom. 2014. 28. 2445-2454

Cyclic terpenoids of contemporary resinous plant detritus and of fossil woods, ambers and coals

USGS Publications Warehouse

Simoneit, B.R.T.; Grimalt, J.O.; Wang, T.-G.; Cox, R.E.; Hatcher, P.G.; Nissenbaum, A.

1986-01-01

Cyclic terpenoids present in the solvent extractable material of fossil woods, ambers and brown coals have been analyzed. The sample series chosen consisted of wood remains preserved in Holocene to Jurassic sediments and a set of of ambers from the Philippines (copalite), Israel, Canada and Dominican Republic. The brown coals selected were from the Fortuna Garsdorf Mine and Miocene formations on Fiji. The fossil wood extracts contained dominant diterpenoid or sesquiterpenoid skeletons, and aromatized species were present at high concentrations, with a major amount of two-ring aromatic compounds. Tricyclic diterpenoids were the predominant compounds in the ambers. Aromatized derivatives were the major components, consisting of one or two aromatic ring species with the abietane and occasionally pimarane skeletons. The saturated structures were comprised primarily of the abietane and pimarane skeletons having from three to five carbon (C1, C2, etc.) substituents. Kaurane and phyllocladane isomers were present in only minor amounts. Bicyclic sesquiterpenoids as saturated and partial or fully aromatized forms were also common in these samples, but only traces of sesterterpenoids and triterpenoid derivatives were found. The brown coal extracts were composed of major amounts of one- and two-ring aromatized terpenoids, with a greater proportion of triterpenoid derivatives than in the case of the woods and ambers. This was especially noticeable for the German coal, where the triterpenoids were predominant. Open C-ring aromatized structures were also present in this coal. Steroid compounds were not detectable, but some hopanes were found as minor components in the German brown coal. An overview of the skeletal structure classes identified in each sample, as well as the general mass spectrometric characteristics of the unknown compounds are included in the present paper. It can be concluded from these structural distributions that aromatization is the main process for the transformation of terrestrial cyclic terpenoids during diagenesis, constituting a general pathway for all terpenoids. ?? 1986 Pergamon Journals Ltd.

Composition of the black crusts from the Saint Denis Basilica, France, as revealed by gas chromatography-mass spectrometry.

PubMed

Gaviño, Maria; Hermosin, Bernardo; Vergès-Belmin, Véronique; Nowik, Witold; Saiz-Jimenez, Cesareo

2004-05-01

The organic fraction of black crusts from Saint Denis Basilica, France, is composed of a complex mixture of aliphatic and aromatic compounds. These compounds were studied by two different analytical approaches: tetramethyl ammonium hydroxide (TMAH) thermochemolysis in combination with gas chromatography-mass spectrometry (GC-MS), and solvent extraction, fractionation by silica column, and identification of the fraction components by GC-MS. The first approach, feasible at the microscale level, is able to supply fairly general information on a wide range of compounds. Using the second approach, we were able to separate the complex mixture of compounds into four fractions, enabling a better identification of the extractable compounds. These compounds belong to different classes: aliphatic hydrocarbons (nalkanes, n-alkenes), aliphatic and aromatic carboxylic acids (n-fatty acids, alpha,omega-dicarboxylic acids, and benzenecarboxylic acids), polycyclic aromatic hydrocarbons (PAH), and molecular biomarkers (isoprenoid hydrocarbons, diterpenoids, and triterpenoids). With each approach, similar classes of compounds were identified, although TMAH thermochemolysis failed to identify compounds present at low concentrations in black crusts. The two proposed methodological approaches are complementary, particularly in the study of polar fractions.

Remedial Investigation/Feasibility Study/Interim Response Actions

DTIC Science & Technology

1988-03-25

organosulfur compounds (CC/FP), organophosphorus compounds (CC/FPD), hydrocarbons (CC/FID), volatile aromatic compounds (GC/ PID ), volatile halogenated...ICP metals, mercury and arsenic (AA). Water samples are being analyzed for volatile halogenated organics (GC/CON), volatile aromatic organics (GC/ PID ...Feb Mar Apr May Jun Jul Aug SepSI - I I I I I • .. I I I ----+----- 685 27-90 so ONSITE DISPOSAL FACILITY .i * 686 27-01 Prep FLUE Plan Fz=m8u> 6e7

Microbial reductive dehalogenation.

PubMed Central

Mohn, W W; Tiedje, J M

1992-01-01

A wide variety of compounds can be biodegraded via reductive removal of halogen substituents. This process can degrade toxic pollutants, some of which are not known to be biodegraded by any other means. Reductive dehalogenation of aromatic compounds has been found primarily in undefined, syntrophic anaerobic communities. We discuss ecological and physiological principles which appear to be important in these communities and evaluate how widely applicable these principles are. Anaerobic communities that catalyze reductive dehalogenation appear to differ in many respects. A large number of pure cultures which catalyze reductive dehalogenation of aliphatic compounds are known, in contrast to only a few organisms which catalyze reductive dehalogenation of aromatic compounds. Desulfomonile tiedjei DCB-1 is an anaerobe which dehalogenates aromatic compounds and is physiologically and morphologically unusual in a number of respects, including the ability to exploit reductive dehalogenation for energy metabolism. When possible, we use D. tiedjei as a model to understand dehalogenating organisms in the above-mentioned undefined systems. Aerobes use reductive dehalogenation for substrates which are resistant to known mechanisms of oxidative attack. Reductive dehalogenation, especially of aliphatic compounds, has recently been found in cell-free systems. These systems give us an insight into how and why microorganisms catalyze this activity. In some cases transition metal complexes serve as catalysts, whereas in other cases, particularly with aromatic substrates, the catalysts appear to be enzymes. Images PMID:1406492

Gondola-shaped tetra-rhenium metallacycles modified evanescent wave infrared chemical sensors for selective determination of volatile organic compounds.

PubMed

Huang, Genin Gary; Lee, Chung-Jay; Tsai, Bo-Chan; Yang, Jyisy; Sathiyendiran, Malaichamy; Lu, Kuang-Lieh

2011-07-15

Water-stable and cavity-contained rhenium metallacycles were synthesized, and their ability to selectively interact with volatile organic compounds (VOCs) systematically studied using attenuated total reflection infrared (ATR-IR) spectroscopy. Integrating the unique properties of rhenium metallacycles into optical sensing technologies significantly improves selectivity in detecting aromatic compounds. To explore the interaction of rhenium metallacycles with VOCs, the surface of ATR sensing elements was modified with the synthesized rhenium metallacycles and used to detect VOCs. The results indicate that rhenium metallacycles have crown ether-like recognition sites, which can selectively interact with aromatic compounds, especially those bearing polar functional groups. The IR absorption bands of rhenium metallacycles shift significantly upon adsorption of aromatic VOCs, revealing a strong interaction between the tetra-rhenium metallacycles and guest aromatic compounds. Optimizing the thickness of the metallacycles coated on the surface of the sensing element led to rapid response in detection. The dynamic range of response was generally up to 30 mg/L with detection limits ca. 30 μg/L. Further studies of the effect of interferences indicate that recovery can be higher than 95% for most of the compounds tested. The results on the flow-cell device indicated that the performances were similar to a static detection system but the detection of VOCs can be largely simplified. Copyright © 2011 Elsevier B.V. All rights reserved.

Characterization of selected volatile organic compounds, polycyclic aromatic hydrocarbons and carbonyl compounds at a roadside monitoring station

NASA Astrophysics Data System (ADS)

Ho, K. F.; Lee, S. C.; Chiu, Gloria M. Y.

Volatile organic compounds (VOCs), PAHs and carbonyl compounds are the major toxic components in Hong Kong. Emissions from motor vehicles have been one of the primary pollution sources in the metropolitan areas throughout Hong Kong for a long time. A 1-yr monitoring program for VOCs, PAHs and carbonyl compounds had been performed at a roadside urban station at Hong Kong Polytechnic University in order to determine the variations and correlations of each selected species (VOCs, PAHs and carbonyl compounds). This study is aimed to analyze toxic volatile organic compounds (benzene, toluene, ethylbenzene and xylene), two carbonyl compounds (formaldehyde, acetaldehyde), and selective polycyclic aromatic hydrocarbons. The monitoring program started from 16 April 1999 to 30 March 2000. Ambient VOC concentrations, many of which originate from the same sources as particulate PAHs and carbonyls compounds, show significant quantities of benzene, toluene and xylenes. Correlations and multivariate analysis of selected gaseous and particulate phase organic pollutants were performed. Source identification by principle component analysis and hierarchical cluster analysis allowed the identification of four sources (factors) for the roadside monitoring station. Factor 1 represents the effect of diesel vehicle exhaust. Factor 2 shows the contribution of aromatic compounds. Factor 3 explains photochemical products—formaldehyde and acetaldehyde. Factor 4 explains the effect of gasoline vehicle exhaust.

The chemistry and beneficial bioactivities of carvacrol (4-isopropyl-2-methylphenol), a component of essential oils produced by aromatic plants and spices

USDA-ARS?s Scientific Manuscript database

Aromatic plants produce organic compounds that may be involved in the defense of plants against phytopathogenic insects, bacteria, fungi, and viruses. One of these compounds called carvacrol that is found in high concentrations in essential oils such as oregano has been reported to exhibit numerous...

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.

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.

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.

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.

Aromatic hydrocarbons from the Middle Jurassic fossil wood of the Polish Jura

NASA Astrophysics Data System (ADS)

Smolarek, Justyna; Marynowski, Leszek

2013-09-01

Aromatic hydrocarbons are present in the fossil wood samples in relatively small amounts. In almost all of the tested samples the dominating aromatic hydrocarbon is perylene and its methyl and dimethyl derivatives. The most important biomarkers present in the aromatic fraction are dehydroabietane, siomonellite and retene, compounds characteristic for conifers. The distribution of discussed compounds is highly variable due to such early diagenetic processes affecting the wood as oxidation and the activity of microorganisms. MPI1 parameter values (methylphenanthrene index) for the majority of the samples are in the range of 0.1 to 0.5, which results in the highly variable values of Rc (converted value of vitrinite reflectance) ranging from 0.45 to 0.70%. Such values suggest that MPI1 parameter is not useful as maturity parameter in case of Middle Jurassic ore-bearing clays, even if measured strictly on terrestrial organic matter (OM). As a result of weathering processes (oxidation) the distribution of aromatic hydrocarbons changes. In the oxidized samples the amount of aromatic hydrocarbons, both polycyclic as well as aromatic biomarkers decreases.

MICROBIAL METABOLISM OF AROMATIC COMPOUNDS I.

PubMed Central

Tabak, Henry H.; Chambers, Cecil W.; Kabler, Paul W.

1964-01-01

Tabak, Henry H. (Robert A. Taft Sanitary Engineering Center, Cincinnati, Ohio), Cecil W. Chambers, and Paul W. Kabler. Microbial metabolism of aromatic carbon compounds. I. Decomposition of phenolic compounds and aromatic hydrocarbons by phenol-adapted bacteria. J. Bacteriol. 87:910–919. 1964.—Bacteria from soil and related environments were selected or adapted to metabolize phenol, hydroxy phenols, nitrophenols, chlorophenols, methylphenols, alkylphenols, and arylphenols when cultured in mineral salts media with the specific substrate as the sole source of carbon. A phenol-adapted culture (substrate-induced enzyme synthesis proven) was challenged in respirometric tests with 104 related compounds; probable significant oxidative activity occurred with 65. Dihydric phenols were generally oxidized; trihydric phenols were not. Cresols and dimethylphenols were oxidized; adding a chloro group increased resistance. Benzoic and hydroxybenzoic acids were oxidized; sulfonated, methoxylated, nitro, and chlorobenzoic acids were not; m-toluic acid was utilized but not the o- and p-isomers. Benzaldehyde and p-hydroxybenzaldehyde were oxidized. In general, nitro- and chloro-substituted compounds and the benzenes were difficult to oxidize. PMID:14137630

Graphene and graphene nanocomposites for the removal of aromatic organic compounds from the water: systematic review

NASA Astrophysics Data System (ADS)

Monsores Paixão, Monique; Tadeu Gomes Vianna, Marco; Marques, Marcia

2018-01-01

Aromatic organic pollutants are highly toxic to the human and environmental health and are considered as priority pollutants by regulatory agencies. Managing contaminated sites with organic pollutants is one of the major environmental challenges today. Of all technologies that have been proposed to remove contaminants, adsorption is recognized worldwide as an attractive option due to its versatility, wide applicability and economic viability. Recent studies report the use of graphene (GN), a recently carbon nanomaterial, and its derivatives in sorption processes for the removal of aromatic organic compounds. The present review has shown that GN structures are a promising alternative to traditional adsorbent materials, with excellent results in the removal of organic compounds from water, due to their unique structural characteristics and great adsorption capacity for organic compounds. Although, there is still a long way to go until that practical applications can be implemented.

Detecting aromatic compounds on planetary surfaces using ultraviolet time-resolved fluorescence spectroscopy

NASA Astrophysics Data System (ADS)

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

2018-02-01

Many aromatic organic molecules exhibit strong and characteristic fluorescence when excited with ultraviolet radiation. As laser excitation in the ultraviolet generates both fluorescence and resonantly enhanced Raman scattering of aromatic vibrational modes, combined Raman and fluorescence instruments have been proposed to search for organic compounds on Mars. In this work the time-resolved fluorescence of a suite of 24 compounds composed of 2-5 ringed alternant, non-alternant, and heterocyclic PAHs was measured. Fluorescence instrumentation with similar specifications to a putative flight instrument was capable of observing the fluorescence decay of these compounds with a sub-ns resolution. Incorporating time-resolved capabilities was also found to increase the ability to discriminate between individual PAHs. Incorporating time-resolved fluorescence capabilities into an ultraviolet gated Raman system intended for a rover or lander can increase the ability to detect and characterize PAHs on planetary surfaces.

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

PubMed

Zakzeski, Joseph; Weckhuysen, Bert M

2011-03-21

The solubilization and aqueous phase reforming of lignin, including kraft, soda, and alcell lignin along with sugarcane bagasse, at low temperatures (T≤498 K) and pressures (P≤29 bar) is reported for the first time for the production of aromatic chemicals and hydrogen. Analysis of lignin model compounds and the distribution of products obtained during the lignin aqueous phase reforming revealed that lignin was depolymerized through disruption of the abundant β-O-4 linkages and, to a lesser extent, the 5-5' carbon-carbon linkages to form monomeric aromatic compounds. The alkyl chains contained on these monomeric compounds were readily reformed to produce hydrogen and simple aromatic platform chemicals, particularly guaiacol and syringol, with the distribution of each depending on the lignin source. The methoxy groups present on the aromatic rings were subject to hydrolysis to form methanol, which was also readily reformed to produce hydrogen and carbon dioxide. The composition of the isolated yields of monomeric aromatic compounds and overall lignin conversion based on these isolated yields varied from 10-15% depending on the lignin sample, with the balance consisting of gaseous products and residual solid material. Furthermore, we introduce the use of a high-pressure autoclave with optical windows and an autoclave with ATR-IR sentinel for on-line in situ spectroscopic monitoring of biomass conversion processes, which provides direct insight into, for example, the solubilization process and aqueous phase reforming reaction of lignin. Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Effects of gasoline aromatic content on emissions of volatile organic compounds and aldehydes from a four-stroke motorcycle.

PubMed

Yao, Yung-Chen; Tsai, Jiun-Horng

2013-01-01

A new four-stroke carburettor motorcycle engine without any engine adjustments was used to study the impact of fuel aromatic content on the exhaust emissions of organic air pollutants (volatile organic compounds and carbonyls). Three levels of aromatic content, i.e. 15, 25, and 50% (vol.) aromatics mixed with gasoline were tested. The emissions of aromatic fuel were compared with those of commercial unleaded gasoline. The results indicated that the A 15 (15 vol% aromatics in gasoline) fuel exhibited the greatest total organic emission improvement among these three aromatic fuels as compared with commercial gasoline, reaching 59%. The highest emission factors of alkanes, alkenes, and carbonyl groups appeared in the reference fuel (RF) among all of the test fuels. A 15 showed the highest emission reduction in alkanes (73%), aromatics (36%), and carbonyls (28%), as compared to those of the RF. The highest emission reduction ofalkenes was observed when using A25 as fuel. A reduction in fuel aromatic content from 50 to 25 and 15 vol% in gasoline decreased benzene and toluene emissions, but increased the aldehyde emissions. In general, the results showed that the highest emission reductions for the most of measured organic pollutants appeared when using A 15 as the fuel.

Aromatic-degrading Sphingomonas isolates from the deep subsurface

DOE Office of Scientific and Technical Information (OSTI.GOV)

Fredrickson, J.K.; Romine, M.F.; Balkwill, D.L.

An obligately aerobic chemoheterotrophic bacterium (strain F199) previously isolated from Southeast Coastal Plain subsurface sediments and shown to degrade toluene, naphthalene, and other aromatic compounds was characterized by analysis of its 16S rRNA nucleotide base sequence and cellular lipid composition. Strain F199 contained 2-OH14:0 and 18:1{omega}7c as the predominant cellular fatty acids and sphingolipids that are characteristic of the genus Sphingomonas. Phylogenetic analysis of its 16SrRNA sequence indicated that F199 was most closely related to Sphingomonas capsulata among the bacteria currently in the Ribosomal Database. Five additional isolates from deep Southeast Coastal Plain sediments were determined by 16S rRNA sequencemore » analysis to be closely related to F199. These strains also contained characteristic sphingolipids. Four of these five strains could also grow on a broad range of aromatic compounds and could mineralize [{sup 14C}]toluene and [{sup 14C}]naphthalene. S. capsulata (ATCC 14666), Sphingomonas paucimobiolis (ATCC 29837), and one of the subsurface isolates were unable to grow on any of the aromatic compounds or mineralize toluene or naphthalene. These results indicate that bacteria within the genus Sphingomonas are present in Southeast Coastal Plain subsurface sediments and that the capacity for degrading a broad range of substituted aromatic compounds appears to be common among Sphingomonas species from this environment. 41 refs., 2 figs., 5 tabs.« less

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

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

PubMed

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

1995-10-01

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.

Pistachio oil (Pistacia vera L. cv. Uzun): Characterization of key odorants in a representative aromatic extract by GC-MS-olfactometry and phenolic profile by LC-ESI-MS/MS.

PubMed

Sonmezdag, Ahmet Salih; Kelebek, Hasim; Selli, Serkan

2018-02-01

Volatile, aroma-active, and phenolic compounds of pistachio oil obtained from cv. Uzun were investigated in the current study. To obtain a representative aromatic extract, three of the most widely used extraction methods were compared using a representative test; the solvent-assisted flavour extraction (SAFE) aromatic extract from pistachio oil was found to be the most representative. A total of 50 aroma compounds were determined in pistachio oil and it was found that terpenes, aldehydes, and alcohols were the most abundant volatile compounds. Applying GC-MS-olfactometry and aroma extract dilution analysis (AEDA) resulted in a total of 14 aroma-active areas being detected in the extract of pistachio oil. In the phenolic fraction obtained by the LC-ESI-MS/MS method, a total of 12 phenolic compounds was found in the pistachio oil, of which seven compounds were reported for the first time. Eriodictyol-7-O-glucoside and protocatechuic acid were the most dominant phenolic compounds. Copyright © 2017 Elsevier Ltd. All rights reserved.

Polyimides Containing Amide And Perfluoroisopropyl Links

NASA Technical Reports Server (NTRS)

Dezem, James F.

1993-01-01

New polyimides synthesized from reactions of aromatic hexafluoroisopropyl dianhydrides with asymmetric amide diamines. Soluble to extent of at least 10 percent by weight at temperature of about 25 degrees C in common amide solvents such as N-methylpyrrolidone, N,N-dimethylacetamide, and N,N-dimethylformamide. Polyimides form tough, flexible films, coatings, and moldings. Glass-transition temperatures ranged from 300 to 365 degrees C, and crystalline melting temperatures observed between 543 and 603 degrees C. Display excellent physical, chemical, and electrical properties. Useful as adhesives, laminating resins, fibers, coatings for electrical and decorative purposes, films, wire enamels, and molding compounds.

Fusing porphyrins with polycyclic aromatic hydrocarbons and heterocycles for optoelectronic applications

DOEpatents

Thompson, Mark E.; Diev, Viacheslav; Hanson, Kenneth; Forrest, Stephen R.

2015-08-18

A compound that can be used as a donor material in organic photovoltaic devices comprising a non-activated porphyrin fused with one or more non-activated polycyclic aromatic rings or one or more non-activated heterocyclic rings can be obtained by a thermal fusion process. The compounds can include structures of Formula I: ##STR00001## By heating the reaction mixture of non-activated porphyrins with non-activated polycyclic aromatic rings or heterocyclic rings to a fusion temperature and holding for a predetermined time, fusion of one or more polycyclic rings or heterocyclic rings to the non-activated porphyrin core in meso,.beta. fashion is achieved resulting in hybrid structures containing a distorted porphyrin ring with annulated aromatic rings. The porphyrin core can be olygoporphyrins.

Formation of highly oxygenated organic molecules from aromatic compounds

NASA Astrophysics Data System (ADS)

Molteni, Ugo; Bianchi, Federico; Klein, Felix; El Haddad, Imad; Frege, Carla; Rossi, Michel J.; Dommen, Josef; Baltensperger, Urs

2018-02-01

Anthropogenic volatile organic compounds (AVOCs) often dominate the urban atmosphere and consist to a large degree of aromatic hydrocarbons (ArHCs), such as benzene, toluene, xylenes, and trimethylbenzenes, e.g., from the handling and combustion of fuels. These compounds are important precursors for the formation of secondary organic aerosol. Here we show that the oxidation of aromatics with OH leads to a subsequent autoxidation chain reaction forming highly oxygenated molecules (HOMs) with an O : C ratio of up to 1.09. This is exemplified for five single-ring ArHCs (benzene, toluene, o-/m-/p-xylene, mesitylene (1,3,5-trimethylbenzene) and ethylbenzene), as well as two conjugated polycyclic ArHCs (naphthalene and biphenyl). We report the elemental composition of the HOMs and show the differences in the oxidation patterns of these ArHCs. A potential pathway for the formation of these HOMs from aromatics is presented and discussed. We hypothesize that AVOCs may contribute substantially to new particle formation events that have been detected in urban areas.

Biodegradation of trichloroethylene and involvement of an aromatic biodegradative pathway.

PubMed Central

Nelson, M J; Montgomery, S O; Mahaffey, W R; Pritchard, P H

1987-01-01

Biodegradation of trichloroethylene (TCE) by bacterial strain G4 resulted in complete dechlorination of the compound, as indicated by the production of inorganic chloride. A component of the water from which strain G4 was isolated that was required for TCE degradation was identified as phenol. Strain G4 degraded TCE in the presence of chloramphenicol only when preinduced with phenol. Toluene, o-cresol. and m-cresol could replace the phenol requirement. Two of the inducers of TCE metabolism, phenol and toluene, apparently induced the same aromatic degradative pathway that cleaved the aromatic ring by meta fission. Cells induced with either phenol or toluene had similar oxidation rates for several aromatic compounds and had similar levels of catechol-2,3-dioxygenase. The results indicate that one or more enzymes of an inducible pathway for aromatic degradation in strain G4 are responsible for the degradation of TCE. PMID:3606099

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 processes. Results from a short summer campaign give indications of the formation of some nitro-PAH by atmospheric chemical reactions.

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.

Electrochemical methods for monitoring of environmental carcinogens.

PubMed

Barek, J; Cvacka, J; Muck, A; Quaiserová, V; Zima, J

2001-04-01

The use of modern electroanalytical techniques, namely differential pulse polarography, differential pulse voltammetry on hanging mercury drop electrode or carbon paste electrode, adsorptive stripping voltammetry and high performance liquid chromatography with electrochemical detection for the determination of trace amounts of carcinogenic N-nitroso compounds, azo compounds, heterocyclic compounds, nitrated polycyclic aromatic hydrocarbons and aromatic and heterocyclic amines is discussed. Scope and limitations of these methods are described and some practical applications based on their combination with liquid-liquid or solid phase extraction are given.

Radiation processing of thermoplastic starch by blending aromatic additives: Effect of blend composition and radiation parameters

NASA Astrophysics Data System (ADS)

Khandal, Dhriti; Mikus, Pierre-Yves; Dole, Patrice; Coqueret, Xavier

2013-03-01

This paper reports on the effects of electron beam (EB) irradiation on poly α-1,4-glucose oligomers (maltodextrins) in the presence of water and of various aromatic additives, as model blends for gaining a better understanding at a molecular level the modifications occurring in amorphous starch-lignin blends submitted to ionizing irradiation for improving the properties of this type of bio-based thermoplastic material. A series of aromatic compounds, namely p-methoxy benzyl alcohol, benzene dimethanol, cinnamyl alcohol and some related carboxylic acids namely cinnamic acid, coumaric acid, and ferulic acid, was thus studied for assessing the ability of each additive to counteract chain scission of the polysaccharide and induce interchain covalent linkages. Gel formation in EB-irradiated blends comprising of maltodextrin was shown to be dependent on three main factors: the type of aromatic additive, presence of glycerol, and irradiation dose. The chain scission versus grafting phenomenon as a function of blend composition and dose were studied using Size Exclusion Chromatography by determining the changes in molecular weight distribution (MWD) from Refractive Index (RI) chromatograms and the presence of aromatic grafts onto the maltodextrin chains from UV chromatograms. The occurrence of crosslinking was quantified by gel fraction measurements allowing for ranking the cross-linking efficiency of the additives. When applying the method to destructurized starch blends, gel formation was also shown to be strongly affected by the moisture content of the sample submitted to irradiation. The results demonstrate the possibility to tune the reactivity of tailored blend for minimizing chain degradation and control the degree of cross-linking.

Identification of Genes and Pathways Related to Phenol Degradation in Metagenomic Libraries from Petroleum Refinery Wastewater

PubMed Central

Silva, Cynthia C.; Hayden, Helen; Sawbridge, Tim; Mele, Pauline; De Paula, Sérgio O.; Silva, Lívia C. F.; Vidigal, Pedro M. P.; Vicentini, Renato; Sousa, Maíra P.; Torres, Ana Paula R.; Santiago, Vânia M. J.; Oliveira, Valéria M.

2013-01-01

Two fosmid libraries, totaling 13,200 clones, were obtained from bioreactor sludge of petroleum refinery wastewater treatment system. The library screening based on PCR and biological activity assays revealed more than 400 positive clones for phenol degradation. From these, 100 clones were randomly selected for pyrosequencing in order to evaluate the genetic potential of the microorganisms present in wastewater treatment plant for biodegradation, focusing mainly on novel genes and pathways of phenol and aromatic compound degradation. The sequence analysis of selected clones yielded 129,635 reads at an estimated 17-fold coverage. The phylogenetic analysis showed Burkholderiales and Rhodocyclales as the most abundant orders among the selected fosmid clones. The MG-RAST analysis revealed a broad metabolic profile with important functions for wastewater treatment, including metabolism of aromatic compounds, nitrogen, sulphur and phosphorus. The predicted 2,276 proteins included phenol hydroxylases and cathecol 2,3- dioxygenases, involved in the catabolism of aromatic compounds, such as phenol, byphenol, benzoate and phenylpropanoid. The sequencing of one fosmid insert of 33 kb unraveled the gene that permitted the host, Escherichia coli EPI300, to grow in the presence of aromatic compounds. Additionally, the comparison of the whole fosmid sequence against bacterial genomes deposited in GenBank showed that about 90% of sequence showed no identity to known sequences of Proteobacteria deposited in the NCBI database. This study surveyed the functional potential of fosmid clones for aromatic compound degradation and contributed to our knowledge of the biodegradative capacity and pathways of microbial assemblages present in refinery wastewater treatment system. PMID:23637911

Self-Assembly and Drug Release Capacities of Organogels via Some Amide Compounds with Aromatic Substituent Headgroups

PubMed Central

Zhang, Lexin; Jiao, Tifeng; Ma, Kai; Xing, Ruirui; Liu, Yamei; Xiao, Yong; Zhou, Jingxin; Zhang, Qingrui; Peng, Qiuming

2016-01-01

In this work, some amide compounds with different aromatic substituent headgroups were synthesized and their gelation self-assembly behaviors in 22 solvents were characterized as new gelators. The obtained results indicated that the size of aromatic substituent headgroups in molecular skeletons in gelators showed crucial effect in the gel formation and self-assembly behavior of all compounds in the solvents used. Larger aromatic headgroups in molecular structures in the synthesized gelator molecules are helpful to form various gel nanostructures. Morphological investigations showed that the gelator molecules can self-assembly and stack into various organized aggregates with solvent change, such as wrinkle, belt, rod, and lamella-like structures. Spectral characterizations suggested that there existed various weak interactions including π-π stacking, hydrogen bonding, and hydrophobic forces due to aromatic substituent headgroups and alkyl substituent chains in molecular structures. In addition, the drug release capacities experiments demonstrated that the drug release rate in present obtained gels can be tuned by adjusting the concentrations of dye. The present work would open up enormous insight to design and investigate new kind of soft materials with designed molecular structures and tunable drug release performance. PMID:28773663

The conversion of BTEX compounds by single and defined mixed cultures to medium-chain-length polyhydroxyalkanoate.

PubMed

Nikodinovic, Jasmina; Kenny, Shane T; Babu, Ramesh P; Woods, Trevor; Blau, Werner J; O'Connor, Kevin E

2008-09-01

Here, we report the use of petrochemical aromatic hydrocarbons as a feedstock for the biotechnological conversion into valuable biodegradable plastic polymers--polyhydroxyalkanoates (PHAs). We assessed the ability of the known Pseudomonas putida species that are able to utilize benzene, toluene, ethylbenzene, p-xylene (BTEX) compounds as a sole carbon and energy source for their ability to produce PHA from the single substrates. P. putida F1 is able to accumulate medium-chain-length (mcl) PHA when supplied with toluene, benzene, or ethylbenzene. P. putida mt-2 accumulates mcl-PHA when supplied with toluene or p-xylene. The highest level of PHA accumulated by cultures in shake flask was 26% cell dry weight for P. putida mt-2 supplied with p-xylene. A synthetic mixture of benzene, toluene, ethylbenzene, p-xylene, and styrene (BTEXS) which mimics the aromatic fraction of mixed plastic pyrolysis oil was supplied to a defined mixed culture of P. putida F1, mt-2, and CA-3 in the shake flasks and fermentation experiments. PHA was accumulated to 24% and to 36% of the cell dry weight of the shake flask and fermentation grown cultures respectively. In addition a three-fold higher cell density was achieved with the mixed culture grown in the bioreactor compared to shake flask experiments. A run in the 5-l fermentor resulted in the utilization of 59.6 g (67.5 ml) of the BTEXS mixture and the production of 6 g of mcl-PHA. The monomer composition of PHA accumulated by the mixed culture was the same as that accumulated by single strains supplied with single substrates with 3-hydroxydecanoic acid occurring as the predominant monomer. The purified polymer was partially crystalline with an average molecular weight of 86.9 kDa. It has a thermal degradation temperature of 350 degrees C and a glass transition temperature of -48.5 degrees C.

Mercury photolytic transformation affected by low-molecular-weight natural organics in water.

PubMed

He, Feng; Zheng, Wang; Liang, Liyuan; Gu, Baohua

2012-02-01

Mechanisms by which dissolved organic matter (DOM) mediates the photochemical reduction of Hg(II) in aquatic ecosystems are not fully understood, owing to the heterogeneous nature and complex structural properties of DOM. In this work, naturally occurring aromatic compounds including salicylic, 4-hydrobenzoic, anthranilic, 4-aminobenzoic, and phthalic acid were systematically studied as surrogates for DOM in order to gain an improved mechanistic understanding of these compounds in the photoreduction of Hg(II) in water. We show that the photoreduction rates of Hg(II) are influenced not only by the substituent functional groups such as -OH, -NH(2) and -COOH on the benzene ring, but also the positioning of these functional groups on the ring structure. The Hg(II) photoreduction rate decreases in the order anthranilic acid>salicylic acid>phthalic acid according to the presence of the -NH(2), -OH, -COOH functional groups on benzoic acid. The substitution position of the functional groups affects reduction rates in the order anthranilic acid>4-aminobenzoic acid and salicylic acid>4-hydroxybenzoic acid. Reduction rates correlate strongly with ultraviolet (UV) absorption of these compounds and their concentrations, suggesting that the formation of organic free radicals during photolysis of these compounds is responsible for Hg(II) photoreduction. These results provide insight into the role of low-molecular-weight organic compounds and possibly DOM in Hg photoredox transformation and may thus have important implications for understanding Hg geochemical cycling in the environment. Copyright © 2011 Elsevier B.V. All rights reserved.

Single kernel method for detection of 2-acetyl-1-pyrroline in aromatic rice germplasm using SPME-GC/MS

USDA-ARS?s Scientific Manuscript database

INTRODUCTION Aromatic rice or fragrant rice, (Oryza sativa L.), has a strong popcorn-like aroma due to the presence of a five-membered N-heterocyclic ring compound known as 2-acetyl-1-pyrroline (2-AP). To date, existing methods for detecting this compound in rice require the use of several kernels. ...

2,4,5-trihydroxy-3-methylacetophenone: A cellulosic chromophore as a case study of aromaticity

Treesearch

Nele Sophie Zwirchmayr; Thomas Elder; Markus Bacher; Andreas Hofinger-Horvath; Paul Kosma; Thomas Rosenau

2017-01-01

The title compound (2,4,5-trihydroxy-3-methylacetophenone, 1) was isolated as chromophore from aged cellulosic pulps. The peculiar feature of the compound is its weak aromatic system that can be converted into nonaromatic (quinoid or cyclic aliphatic) tautomers, depending on the conditions and reaction partners. In alkaline media, the participation of quinoid canonic...

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

USDA-ARS?s Scientific Manuscript database

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...

Aerobic Biodegradation of Trichloroethylene.

DTIC Science & Technology

1987-07-01

into C02 and unidentified nonvolatile products. Phenol, 41 toiin- andq- cresol were found to replace the site water requirement for TCE metabolism...identified as phenol. Other aromatic compounds that could support TCE degradation were toluene, o- cresol , and m- cresol . The degradation could be...Production...... .. .. .. . 17 4. Test for the Catechol Ortho °Ring-Fission Pathway . 18 5. Oxidation of Aromatic Compounds ............. .18 6

Polycyclic aromatic hydrocarbons degradation by marine-derived basidiomycetes: optimization of the degradation process.

PubMed

Vieira, Gabriela A L; Magrini, Mariana Juventina; Bonugli-Santos, Rafaella C; Rodrigues, Marili V N; Sette, Lara D

2018-05-03

Pyrene and benzo[a]pyrene (BaP) are high molecular weight polycyclic aromatic hydrocarbons (PAHs) recalcitrant to microbial attack. Although studies related to the microbial degradation of PAHs have been carried out in the last decades, little is known about degradation of these environmental pollutants by fungi from marine origin. Therefore, this study aimed to select one PAHs degrader among three marine-derived basidiomycete fungi and to study its pyrene detoxification/degradation. Marasmiellus sp. CBMAI 1062 showed higher levels of pyrene and BaP degradation and was subjected to studies related to pyrene degradation optimization using experimental design, acute toxicity, organic carbon removal (TOC), and metabolite evaluation. The experimental design resulted in an efficient pyrene degradation, reducing the experiment time while the PAH concentration applied in the assays was increased. The selected fungus was able to degrade almost 100% of pyrene (0.08mgmL -1 ) after 48h of incubation under saline condition, without generating toxic compounds and with a TOC reduction of 17%. Intermediate metabolites of pyrene degradation were identified, suggesting that the fungus degraded the compound via the cytochrome P450 system and epoxide hydrolases. These results highlight the relevance of marine-derived fungi in the field of PAH bioremediation, adding value to the blue biotechnology. Copyright © 2018. Published by Elsevier Editora Ltda.

Molecular Characterization of Brown Carbon in Biomass Burning Aerosol Particles.

PubMed

Lin, Peng; Aiona, Paige K; Li, Ying; Shiraiwa, Manabu; Laskin, Julia; Nizkorodov, Sergey A; Laskin, Alexander

2016-11-01

Emissions from biomass burning are a significant source of brown carbon (BrC) in the atmosphere. In this study, we investigate the molecular composition of freshly emitted biomass burning organic aerosol (BBOA) samples collected during test burns of sawgrass, peat, ponderosa pine, and black spruce. We demonstrate that both the BrC absorption and the chemical composition of light-absorbing compounds depend significantly on the type of biomass fuels. Common BrC chromophores in the selected BBOA samples include nitro-aromatics, polycyclic aromatic hydrocarbon derivatives, and polyphenols spanning a wide range of molecular weights, structures, and light absorption properties. A number of biofuel-specific BrC chromophores are observed, indicating that some of them may be used as source-specific markers of BrC. On average, ∼50% of the light absorption in the solvent-extractable fraction of BBOA can be attributed to a limited number of strong BrC chromophores. The absorption coefficients of BBOA are affected by solar photolysis. Specifically, under typical atmospheric conditions, the 300 nm absorbance decays with a half-life of ∼16 h. A "molecular corridor" analysis of the BBOA volatility distribution suggests that many BrC compounds in the fresh BBOA have low saturation mass concentration (<1 μg m -3 ) and will be retained in the particle phase under atmospherically relevant conditions.

Adsorption of aromatic compounds by carbonaceous adsorbents: a comparative study on granular activated carbon, activated carbon fiber, and carbon nanotubes.

PubMed

Zhang, Shujuan; Shao, Ting; Kose, H Selcen; Karanfil, Tanju

2010-08-15

Adsorption of three aromatic organic compounds (AOCs) by four types of carbonaceous adsorbents [a granular activated carbon (HD4000), an activated carbon fiber (ACF10), two single-walled carbon nanotubes (SWNT, SWNT-HT), and a multiwalled carbon nanotube (MWNT)] with different structural characteristics but similar surface polarities was examined in aqueous solutions. Isotherm results demonstrated the importance of molecular sieving and micropore effects in the adsorption of AOCs by carbonaceous porous adsorbents. In the absence of the molecular sieving effect, a linear relationship was found between the adsorption capacities of AOCs and the surface areas of adsorbents, independent of the type of adsorbent. On the other hand, the pore volume occupancies of the adsorbents followed the order of ACF10 > HD4000 > SWNT > MWNT, indicating that the availability of adsorption site was related to the pore size distributions of the adsorbents. ACF10 and HD4000 with higher microporous volumes exhibited higher adsorption affinities to low molecular weight AOCs than SWNT and MWNT with higher mesopore and macropore volumes. Due to their larger pore sizes, SWNTs and MWNTs are expected to be more efficient in adsorption of large size molecules. Removal of surface oxygen-containing functional groups from the SWNT enhanced adsorption of AOCs.

The shikimate pathway: review of amino acid sequence, function and three-dimensional structures of the enzymes.

PubMed

Mir, Rafia; Jallu, Shais; Singh, T P

2015-06-01

The aromatic compounds such as aromatic amino acids, vitamin K and ubiquinone are important prerequisites for the metabolism of an organism. All organisms can synthesize these aromatic metabolites through shikimate pathway, except for mammals which are dependent on their diet for these compounds. The pathway converts phosphoenolpyruvate and erythrose 4-phosphate to chorismate through seven enzymatically catalyzed steps and chorismate serves as a precursor for the synthesis of variety of aromatic compounds. These enzymes have shown to play a vital role for the viability of microorganisms and thus are suggested to present attractive molecular targets for the design of novel antimicrobial drugs. This review focuses on the seven enzymes of the shikimate pathway, highlighting their primary sequences, functions and three-dimensional structures. The understanding of their active site amino acid maps, functions and three-dimensional structures will provide a framework on which the rational design of antimicrobial drugs would be based. Comparing the full length amino acid sequences and the X-ray crystal structures of these enzymes from bacteria, fungi and plant sources would contribute in designing a specific drug and/or in developing broad-spectrum compounds with efficacy against a variety of pathogens.

The influence of the Tbeta level upon fluorescence and laser properties of aromatic compounds.

PubMed

Nijegorodov, N; Winkoun, D P; Nkoma, J S

2004-07-01

The fluorescence and laser properties of seven specially chosen aromatic compounds are studied at 293 degrees C. The quantum yield of fluorescence, gamma, decay times, tauf, of the deaerated and non-deaerated solutions are measured. The oscillator strength, fe, fluorescence rate constants, kf, natural lifetimes, tauT0, and intersystem crossing rate constants, kST, are calculated. Some laser parameters are calculated or measured experimentally. It is found that the position of the Tbeta level plays an important role in the fluorescence and laser properties of aromatic compounds. If the Tbeta level is situated below the Sp level, it decreases the quantum yield of fluorescence and the decay time and increases the threshold of laser action. If, due to some structural changes of a molecule, the Tbeta level is situated higher than the Sp level, then the quantum yield of fluorescence and the decay times are increasing and the threshold of laser action is decreasing. Such influence of the position of the Tbeta level upon fluorescence and laser properties of aromatic compound is explained by the fact that the Sp level mixes with the Tbeta level more readily than with other taupipi* levels.

Dramatic Influence of Ionic Liquid and Ultrasound Irradiation on the Electrophilic Sulfinylation of Aromatic Compounds by Sulfinic Esters.

PubMed

Nguyen, Ngoc-Lan Thi; Vo, Hong-Thom; Duus, Fritz; Luu, Thi Xuan Thi

2017-09-04

The sulfinylation reaction of aromatic and hetero-aromatic compounds with sulfinic esters as electrophiles has been investigated in different ionic liquids and by means of different Lewis acid salts in order to get moderate to good yields of asymmetrical sulfoxides. Mixtures of 1-butyl-3-methylimidazolium chloride and aluminum chloride were found to be the most efficient and recyclable reaction framework. Ultrasound sonication appeared to be the most useful and green activation method to afford the sulfoxides in yields better than or equivalent to those obtained under the longer-lasting conventional stirring conditions.

[Simultaneous analysis of aromatic aldehydes and coumarins with high pressure liquid chromatography. Application to wines and brandies stored in oak barrels].

PubMed

Salagoity-Auguste, M H; Tricard, C; Sudraud, P

1987-04-17

Aromatic aldehydes (vanillin, syringaldehyde, coniferaldehyde and sinapaldehyde) and coumarins (esculetin, umbelliferone, scopoletin and methylumbelliferone) are natural wood compounds. Storage of wines and brandies in oak barrels increases notably aldehydes and coumarins (particularly scopoletin) concentrations. These compounds were separated by high-performance liquid chromatography, on hydrocarbon bonded reversed-phase packings, with a water-acetonitrile elution gradient. They were first extracted from wines and brandies by diethyl ether and then injected on chromatographic column. A double detection was used to determine simultaneously aromatic aldehydes and coumarins by UV absorption and fluorescence respectively.

Characterization of organic aromatic compounds in soils affected by an uncontrolled tire landfill fire through the use of comprehensive two-dimensional gas chromatography-time-of-flight mass spectrometry.

PubMed

Escobar-Arnanz, J; Mekni, S; Blanco, G; Eljarrat, E; Barceló, D; Ramos, L

2018-02-09

Discarded vehicle tires have become an increasing concern worldwide due to the enormous amount of wastes generated and the increasing evidence of health problems associated to their disposal and accidental combustion. Previous studies conducted involving either simulated or open uncontrolled tire fires have identified aromatics belonging to two main classes, volatile organic compounds and polycyclic aromatic compounds (PAHs), as the most relevant chemicals generated in these burning processes. As a consequence, and due to their recognized toxicity, most studies reported up to now have mainly focused on these two categories of compounds being information concerning the possible occurrence of other aromatic classes rather limited. In this study, the enhanced separation power and structural confirmation capabilities provided by comprehensive two-dimensional gas chromatography-time-of-flight mass spectrometry (GC×GC-ToF MS) has been used, for the first time, for the non-targeted analysis of soils impacted by a tire fire and an ash collected at the scene of the fire. In total, 118 volatile and semi-volatile aromatic compounds have been differentiated. Among them, 104 compounds have been either positively or tentatively identified. PAHs with 3-5 rings and their alkyl-derivatives were the most numerous and relevant classes in the investigated samples. A significant number of sulfur, oxygen- and nitrogen-containing PAHs were also detected in the samples. The application of a script function to the raw GC×GC-ToF MS data allowed the fast filtering and automatic recognition of compounds containing halogens in their structure. This part of the study evidenced that only a limited number of regulated persistent organic pollutants were present in the investigated samples. However, it also revealed the presence of emerging organophosphorous flame retardants, whose levels in tire fire impacted soils are reported for the first time. Copyright © 2017 Elsevier B.V. All rights reserved.

Volatile profiles of aromatic and non-aromatic rice

USDA-ARS?s Scientific Manuscript database

Rice is enjoyed by many people as a staple food because of its flavor and texture. Some scented varieties command a premium in the marketplace because of their distinctive aroma and flavor. The compound most commonly associated with the popcorn or nutty scent of aromatic rice is 2-acetyl-1-pyrroline...

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

EPA Pesticide Factsheets

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

SIMULTANEOUS DTERMINATION OF CHROMATE AND AROMATIC HYDROCARBONS IN ENVIRONMENTAL SAMPLES BY CAPILLARY ELECTROPHORESIS

EPA Science Inventory

An analytical method was developed to determine simultaneously, the inorganic anion CrO2-4, and organic aromatic compounds including benzoate, 2-Cl-benzoate, phenol, m-cresol and o-/p-cresol by capillary electrophoresis (CE). Chromate and the aromatics were separated in a relativ...

High temperature normal phase liquid chromatography of aromatic hydrocarbons on bare zirconia.

PubMed

Paproski, Richard E; Liang, Chen; Lucy, Charles A

2011-11-04

The normal phase HPLC behavior of a bare zirconia column was studied at temperatures up to 200 °C using a hexane mobile phase. The use of elevated column temperatures significantly decreased the retention of twenty five aromatic model compounds according to the van't Hoff equation (>30-fold decrease for some compounds). Large improvements in peak shape, efficiency (>2.2-fold), aromatic group-type selectivity, and column re-equilibration times (>5-fold) were obtained at elevated temperatures. The thermal decomposition of two polar nitrogen compounds (indole and carbazole) was observed in a hexane/dichloromethane mobile phase at temperatures greater than 100 °C. The first order decomposition of carbazole was studied in further detail. Copyright © 2011 Elsevier B.V. All rights reserved.

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.

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.

Determination of total and polycyclic aromatic hydrocarbons in aviation jet fuel.

PubMed

Bernabei, M; Reda, R; Galiero, R; Bocchinfuso, G

2003-01-24

The aviation jet fuel widely used in turbine engine aircraft is manufactured from straight-run kerosene. The combustion quality of jet fuel is largely related to the hydrocarbon composition of the fuel itself; paraffins have better burning properties than aromatic compounds, especially naphthalenes and light polycyclic aromatic hydrocarbons (PAHs), which are characterised as soot and smoke producers. For this reason the burning quality of fuel is generally measured as smoke fermation. This evaluation is carried out with UV spectrophotometric determination of total naphthalene hydrocarbons and a chromatographic analysis to determine the total aromatic compounds. These methods can be considered insufficient to evaluate the human health impact of these compounds due to their inability to measure trace (ppm) amounts of each aromatic hyrcarbon and each PAH in accordance with limitations imposed because of their toxicological properties. In this paper two analytical methods are presented. Both are based on a gas chromatographic technique with a mass detector operating in be selected ion monitoring mode. The first method was able to determine more than 60 aromatic hydrocarbons in a fuel sample in a 35-min chromatographic run, while the second was able to carry out the analysis of more than 30 PAHs in a 40-min chromatographic run. The linearity and sensitivity of the methods in measuring these analytes at trace levels are described.

A 150-year record of polycyclic aromatic compound (PAC) deposition from high Andean Cajas National Park, southern Ecuador.

PubMed

Bandowe, Benjamin A Musa; Fränkl, Lea; Grosjean, Martin; Tylmann, Wojciech; Mosquera, Pablo V; Hampel, Henrietta; Schneider, Tobias

2018-04-15

The temporal profiles of polycyclic aromatic compounds (PACs) in lake sediments reflect past changes in emissions, transport and deposition of these pollutants and, thus, record natural and anthropogenic processes. We document fluxes of PACs [(polycyclic aromatic hydrocarbons (PAHs), oxygenated PAHs (OPAHs) and azaarenes (AZAs)] deposited in two tropical high-altitude lakes in the Cajas National Park (Ecuadorian Andes, 2°50'S, 79°10'W). In remote and high elevation Laguna Fondococha (4130m a.s.l.), the temporal fluxes of OPAHs and AZAs were similar to those of PAHs suggesting similar sources. A significant increase of PAC deposition after the 1950s reflects Ecuador's economic development. PAH fluxes were relatively low (∑27PAHs (without retene and perylene): 0.86-11.21ngcm -2 yr -1 ) with a composition pattern typical for long-range atmospheric transport (high 9-fluorenone/fluorene ratios) and biomass burning (30% low molecular weight PAHs). PAHs diagnostic of high temperature combustion (industry, traffic) make up 20-25% of total PAHs. Perylene concentrations increase linearly with increasing sediment depth suggesting diagenetic in-situ production. At lower elevations (Laguna Llaviucu, 3140m a.s.l.) and closer to urban areas, PAC fluxes in the past decades were 4-5 times higher than in the remote high-elevation lake. Laguna Llaviucu also showed higher concentrations of high molecular weight pyrogenic PAHs and a greater diversity of AZAs. Individual OPAHs and AZAs reflect mainly combustion activities. In Laguna Llaviucu, which is at a lower elevation (3140m a.s.l.) and closer to the city, molecular ratios suggest short-range atmospheric transport and deposition of PACs. A very foggy climate (170 rainy days per year) with the precipitation maximum at 3500m removes PACs very efficiently (by wet deposition) from the atmosphere at very short distances from emission sources. This partly explains why L. Llaviucu shows higher fluxes of PACs than the higher elevation L. Fondococha. This study presents the first historical record of organic pollutants from environmental archives in Ecuador. Copyright © 2017 Elsevier B.V. All rights reserved.

Sulfur Transformation during Microwave and Conventional Pyrolysis of Sewage Sludge.

PubMed

Zhang, Jun; Zuo, Wei; Tian, Yu; Chen, Lin; Yin, Linlin; Zhang, Jie

2017-01-03

The sulfur distributions and evolution of sulfur-containing compounds in the char, tar and gas fractions were investigated during the microwave and conventional pyrolysis of sewage sludge. Increased accumulation of sulfur in the char and less production of H 2 S were obtained from microwave pyrolysis at higher temperatures (500-800 °C). Three similar conversion pathways were identified for the formation of H 2 S during microwave and conventional pyrolysis. The cracking of unstable mercaptan structure in the sludge contributed to the release of H 2 S below 300 °C. The decomposition of aliphatic-S compounds in the tars led to the formation of H 2 S (300-500 °C). The thermal decomposition of aromatic-S compounds in the tars generated H 2 S from 500 to 800 °C. However, the secondary decomposition of thiophene-S compounds took place only in conventional pyrolysis above 700 °C. Comparing the H 2 S contributions from microwave and conventional pyrolysis, the significant increase of H 2 S yields in conventional pyrolysis was mainly attributed to the decomposition of aromatic-S (increasing by 10.4%) and thiophene-S compounds (11.3%). Further investigation on the inhibition mechanism of H 2 S formation during microwave pyrolysis confirmed that, with the special heating characteristics and relative shorter residence time, microwave pyrolysis promoted the retention of H 2 S on CaO and inhibited the secondary cracking of thiophene-S compounds at higher temperatures.

Functional Group Analysis.

ERIC Educational Resources Information Center

Smith, Walter T., Jr.; Patterson, John M.

1984-01-01

Literature on analytical methods related to the functional groups of 17 chemical compounds is reviewed. These compounds include acids, acid azides, alcohols, aldehydes, ketones, amino acids, aromatic hydrocarbons, carbodiimides, carbohydrates, ethers, nitro compounds, nitrosamines, organometallic compounds, peroxides, phenols, silicon compounds,…

Microbial degradation of terrigenous dissolved organic matter and potential consequences for carbon cycling in brown-water streams.

PubMed

Fasching, Christina; Behounek, Barbara; Singer, Gabriel A; Battin, Tom J

2014-05-15

Streams receive substantial terrestrial deliveries of dissolved organic matter (DOM). The chromophoric (CDOM) fraction of terrestrial deliveries confers the brown colour to streamwater, often understood as browning, and plays a central role in aquatic photochemistry and is generally considered resistant to microbial metabolism. To assess the relevance of terrigenous DOM for carbon fluxes mediated by stream microorganisms, we determined the bioavailable fraction of DOM and microbial carbon use efficiency (CUE), and related these measures to partial pressure of CO2 in headwater streams spanning across a browning gradient. Fluorescence and absorbance analyses revealed high molecular weight and aromaticity, and elevated contributions from humic-like components to characterize terrestrial CDOM. We found that microorganisms metabolized this material at the cost of low CUE and shifted its composition (from fluorescence and absorbance) towards less aromatic and low-molecular weight compounds. Respiration (from CUE) was related to CO2 supersaturation in streams and this relationship was modulated by DOM composition. Our findings imply that terrigenous DOM is respired by microorganisms rather than incorporated into their biomass, and that this channelizes terrigenous carbon to the pool of CO2 potentially outgassing from streams into the atmosphere. This finding may gain relevance as major terrigenous carbon stores become mobilized and browning progresses.

Microbial degradation of terrigenous dissolved organic matter and potential consequences for carbon cycling in brown-water streams

PubMed Central

Fasching, Christina; Behounek, Barbara; Singer, Gabriel A.; Battin, Tom J.

2014-01-01

Streams receive substantial terrestrial deliveries of dissolved organic matter (DOM). The chromophoric (CDOM) fraction of terrestrial deliveries confers the brown colour to streamwater, often understood as browning, and plays a central role in aquatic photochemistry and is generally considered resistant to microbial metabolism. To assess the relevance of terrigenous DOM for carbon fluxes mediated by stream microorganisms, we determined the bioavailable fraction of DOM and microbial carbon use efficiency (CUE), and related these measures to partial pressure of CO2 in headwater streams spanning across a browning gradient. Fluorescence and absorbance analyses revealed high molecular weight and aromaticity, and elevated contributions from humic-like components to characterize terrestrial CDOM. We found that microorganisms metabolized this material at the cost of low CUE and shifted its composition (from fluorescence and absorbance) towards less aromatic and low-molecular weight compounds. Respiration (from CUE) was related to CO2 supersaturation in streams and this relationship was modulated by DOM composition. Our findings imply that terrigenous DOM is respired by microorganisms rather than incorporated into their biomass, and that this channelizes terrigenous carbon to the pool of CO2 potentially outgassing from streams into the atmosphere. This finding may gain relevance as major terrigenous carbon stores become mobilized and browning progresses. PMID:24828296

Effects of o-vanillin on K⁺ transport of red blood cells from patients with sickle cell disease.

PubMed

Hannemann, A; Cytlak, U M C; Gbotosho, O T; Rees, D C; Tewari, S; Gibson, J S

2014-01-01

Aromatic aldehydes like o-vanillin were designed to reduce the complications of sickle cell disease (SCD) by interaction with HbS, to reduce polymerisation and RBC sickling. Present results show that o-vanillin also directly affects RBC membrane permeability. Both the K(+)-Cl(-) cotransporter (KCC) and the Ca(2+)-activated K(+) channel (or Gardos channel) were inhibited with IC50 of about 0.3 and 1 mM, respectively, with activities almost completely abolished by 5 mM. Similar effects were observed in RBCs treated with the thiol reacting reagent N-ethylmaleimide or with the Ca(2+) ionophore A23187, to circumvent any action via HbS polymerisation. The deoxygenation-induced cation conductance (sometimes termed P(sickle)) was partially inhibited, whilst deoxygenation-induced exposure of phosphatidylserine was completely abrogated. Na(+)/K(+) pump activity was also reduced. Notwithstanding, o-vanillin stimulated K(+) efflux through an unidentified pathway and resulted in reduction in cell volume (as measured by wet weight-dry weight). These actions are relevant to understanding how aromatic aldehydes may affect RBC membrane permeability per se as well as HbS polymerisation and thereby inform design of compounds most efficacious in ameliorating the complications of SCD. Copyright © 2014. Published by Elsevier Inc.

Effects of o-vanillin on K+ transport of red blood cells from patients with sickle cell disease

PubMed Central

Hannemann, A.; Cytlak, U.M.C.; Gbotosho, O.T.; Rees, D.C.; Tewari, S.; Gibson, J.S.

2014-01-01

Aromatic aldehydes like o-vanillin were designed to reduce the complications of sickle cell disease (SCD) by interaction with HbS, to reduce polymerisation and RBC sickling. Present results show that o-vanillin also directly affects RBC membrane permeability. Both the K+–Cl− cotransporter (KCC) and the Ca2 +-activated K+ channel (or Gardos channel) were inhibited with IC50 of about 0.3 and 1 mM, respectively, with activities almost completely abolished by 5 mM. Similar effects were observed in RBCs treated with the thiol reacting reagent N-ethylmaleimide or with the Ca2 + ionophore A23187, to circumvent any action via HbS polymerisation. The deoxygenation-induced cation conductance (sometimes termed Psickle) was partially inhibited, whilst deoxygenation-induced exposure of phosphatidylserine was completely abrogated. Na+/K+ pump activity was also reduced. Notwithstanding, o-vanillin stimulated K+ efflux through an unidentified pathway and resulted in reduction in cell volume (as measured by wet weight − dry weight). These actions are relevant to understanding how aromatic aldehydes may affect RBC membrane permeability per se as well as HbS polymerisation and thereby inform design of compounds most efficacious in ameliorating the complications of SCD. PMID:24594314

Alkylphenols, polycyclic aromatic hydrocarbons, and organochlorines in sediment from Lake Shihwa, Korea: Instrumental and bioanalytical characterization

DOE Office of Scientific and Technical Information (OSTI.GOV)

Khim, J.S.; Villeneuve, D.L.; Kannan, K.

1999-11-01

Lake Shihwa is an artificial lake, located on the west coast of Korea, that has experienced environmental deterioration since 1994, when it was formed by construction of a sea dike. This study used instrumental analysis and in vitro bioassays to characterize organic contaminants in sediment collected from 11 stations on Lake Shihwa. Alkylphenol (AP) concentrations in Lake Shihwa sediment ranged from 20.2 to 1,820 ng/g nonylphenol and from 4.69 to 50.5 ng/g octylphenol, on a dry weight basis. Maximum concentrations of polycyclic aromatic hydrocarbons (PAHs), organochlorine pesticides, and polychlorinated biphenyls (PCBs) were 30.8, 2.26, and 12.3 ng/g (dry weight), respectively.more » Significant estrogenic activity was associated with fractions containing APs. Mass-balance analysis suggested that reported concentrations of APs account for less than 20% of the estrogenic activity observed. No significant dioxin like activity was associated with fractions containing classic aryl hydrocarbon receptor agonists, such as PCBs, but the mid-polarity fractions containing PAHs and most polar fractions yielded significant dioxin like activity. Overall, most of the in vitro bioassay responses appear to have been caused by unidentified and/or undetectable compounds associated with Lake Shihwa sediment.« less

Selective cleavage of the C(α)-C(β) linkage in lignin model compounds via Baeyer-Villiger oxidation.

PubMed

Patil, Nikhil D; Yao, Soledad G; Meier, Mark S; Mobley, Justin K; Crocker, Mark

2015-03-21

Lignin is an amorphous aromatic polymer derived from plants and is a potential source of fuels and bulk chemicals. Herein, we present a survey of reagents for selective stepwise oxidation of lignin model compounds. Specifically, we have targeted the oxidative cleavage of Cα-Cβ bonds as a means to depolymerize lignin and obtain useful aromatic compounds. In this work, we prepared several lignin model compounds that possess structures, characteristic reactivity, and linkages closely related to the parent lignin polymer. We observed that selective oxidation of benzylic hydroxyl groups, followed by Baeyer-Villiger oxidation of the resulting ketones, successfully cleaves the Cα-Cβ linkage in these model compounds.

Chemoenzymatic syntheses of prenylated aromatic small molecules using Streptomyces prenyltransferases with relaxed substrate specificities

PubMed Central

Kumano, Takuto; Richard, Stéphane B.; Noel, Joseph P.; Nishiyama, Makoto; Kuzuyama, Tomohisa

2010-01-01

NphB is a soluble prenyltransferase from Streptomyces sp. strain CL190 that attaches a geranyl group to a 1,3,6,8-tetrahydroxynaphthalene-derived polyketide during the biosynthesis of anti-oxidant naphterpin. Here we report multiple chemoenzymatic syntheses of various prenylated compounds from aromatic substrates including flavonoids using two prenyltransferases NphB and SCO7190, a NphB homolog from Streptomyces coelicolor A3(2), as biocatalysts. NphB catalyzes carbon–carbon-based and carbon–oxygen-based geranylation of a diverse collection of hydroxyl-containing aromatic acceptors. Thus, this simple method using the prenyltransferases can be used to explore novel prenylated aromatic compounds with biological activities. Kinetic studies with NphB reveal that the prenylation reaction follows a sequential ordered mechanism. PMID:18682327

Di(hydroxyphenyl)- benzimidazole monomers

NASA Technical Reports Server (NTRS)

Connell, John W. (Inventor); Hergenrother, Paul M. (Inventor); Smith, Joseph G. (Inventor)

1993-01-01

Di(hydroxyphenyl)benzimidazole monomers were prepared from phenyl-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.

Quantitative analysis and health risk assessment of polycyclic aromatic hydrocarbons in edible vegetable oils marketed in Shandong of China.

PubMed

Jiang, Dafeng; Xin, Chenglong; Li, Wei; Chen, Jindong; Li, Fenghua; Chu, Zunhua; Xiao, Peirui; Shao, Lijun

2015-09-01

This work studies on the quantitative analysis and health risk assessment of polycyclic aromatic hydrocarbons (PAHs) in edible vegetable oils in Shandong, China. The concentrations of 15 PAHs in 242 samples were determined by high performance liquid chromatography coupled with fluorescence detection. The results indicated that the mean concentration of 15 PAHs in oil samples was 54.37 μg kg(-1). Low molecular weight PAH compounds were the predominant contamination. Especially, the carcinogenic benzo(a)pyrene (BaP) was detected at a mean concentration of 1.28 μg kg(-1), which was lower than the limit of European Union and China. A preliminary evaluation of human health risk assessment for PAHs was accomplished using BaP toxic equivalency factors and the incremental lifetime cancer risk (ILCR). The ILCR values for children, adolescents, adults, and seniors were all larger than 1 × 10(-6), indicating a high potential carcinogenic risk on the dietary exposed populations. Copyright © 2015 Elsevier Ltd. All rights reserved.

Heterogeneous Diels–Alder catalysis for biomass-derived aromatic compounds

DOE PAGES

Settle, Amy E.; Berstis, Laura; Rorrer, Nicholas A.; ...

2017-05-17

In this tutorial review, we provide an overview of heterogeneous Diels–Alder catalysis for the production of lignocellulosic biomass-derived aromatic compounds. Diels–Alder reactions afford an extremely selective and efficient route for carbon–carbon cycloadditions to produce intermediates that can readily undergo subsequent dehydration or dehydrogenation reactions for aromatization. As a result, catalysis of Diels–Alder reactions with biomass-derived dienes and dienophiles has seen a growth of interest in recent years; however, significant opportunities remain to (i) tailor heterogeneous catalyst materials for tandem Diels–Alder and aromatization reactions, and (ii) utilize biomass-derived dienes and dienophiles to access both conventional and novel aromatic monomers. As such,more » this review discusses the mechanistic aspects of Diels–Alder reactions from both an experimental and computational perspective, as well as the synergy of Brønsted–Lewis acid catalysts to facilitate tandem Diels–Alder and aromatization reactions. Heterogeneous catalyst design strategies for Diels–Alder reactions are reviewed for two exemplary solid acid catalysts, zeolites and polyoxometalates, and recent efforts for targeting direct replacement aromatic monomers from biomass are summarized. In conclusion, we point out important research directions for progressing Diels–Alder catalysis to target novel, aromatic monomers with chemical functionality that enables new properties compared to monomers that are readily accessible from petroleum.« less

Effects of peat fires on the characteristics of humic acid extracted from peat soil in Central Kalimantan, Indonesia.

PubMed

Yustiawati; Kihara, Yusuke; Sazawa, Kazuto; Kuramitz, Hideki; Kurasaki, Masaaki; Saito, Takeshi; Hosokawa, Toshiyuki; Syawal, M Suhaemi; Wulandari, Linda; Hendri I; Tanaka, Shunitz

2015-02-01

When peat forest fires happen, it leads to burn soil and also humic acids as a dominant organic matter contained in peat soil as well as the forest. The structure and properties of humic acids vary depending on their origin and environment, therefore the transformation of humic acid is also diverse. The impacts of the peat fires on peat soil from Central Kalimantan, Indonesia were investigated through the characterization of humic acids, extracted from soil in burnt and unburnt sites. The characterization of humic acids was performed by elemental composition, functional groups, molecular weight by HPSEC, pyrolysate compounds by pyrolysis-GC/MS, fluorescence spectrum by 3DEEM spectrofluorometer, and thermogravimetry. The elemental composition of each humic substance indicated that the value of H/C and O/C of humic acids from burnt sites were lower than that from unburnt sites. The molecular weight of humic acids from burnt sites was also lower than that from unburnt sites. Pyrolysate compounds of humic acids from unburnt sites differed from those of humic acids from burnt soil. The heating experiment showed that burning process caused the significant change in the properties of humic acids such as increasing the aromaticity and decreasing the molecular weight.

The Aspergillus niger faeB gene encodes a second feruloyl esterase involved in pectin and xylan degradation and is specifically induced in the presence of aromatic compounds.

PubMed

de Vries, Ronald P; vanKuyk, Patricia A; Kester, Harry C M; Visser, Jaap

2002-04-15

The faeB gene encoding a second feruloyl esterase from Aspergillus niger has been cloned and characterized. It consists of an open reading frame of 1644 bp containing one intron. The gene encodes a protein of 521 amino acids that has sequence similarity to that of an Aspergillus oryzae tannase. However, the encoded enzyme, feruloyl esterase B (FAEB), does not have tannase activity. Comparison of the physical characteristics and substrate specificity of FAEB with those of a cinnamoyl esterase from A. niger [Kroon, Faulds and Williamson (1996) Biotechnol. Appl. Biochem. 23, 255-262] suggests that they are in fact the same enzyme. The expression of faeB is specifically induced in the presence of certain aromatic compounds, but not in the presence of other constituents present in plant-cell-wall polysaccharides such as arabinoxylan or pectin. The expression profile of faeB in the presence of aromatic compounds was compared with the expression of A. niger faeA, encoding feruloyl esterase A (FAEA), and A. niger bphA, the gene encoding a benzoate-p-hydroxylase. All three genes have different subsets of aromatic compounds that induce their expression, indicating the presence of different transcription activating systems in A. niger that respond to aromatic compounds. Comparison of the activity of FAEA and FAEB on sugar-beet pectin and wheat arabinoxylan demonstrated that they are both involved in the degradation of both polysaccharides, but have opposite preferences for these substrates. FAEA is more active than FAEB towards wheat arabinoxylan, whereas FAEB is more active than FAEA towards sugar-beet pectin.

Contaminated sediments from tributaries of the Great Lakes: Chemical characterization and carcinogenic effects in medaka (Oryzias latipes)

USGS Publications Warehouse

Besser, John M.; Schmitt, Christopher J.; Harshbarger, John C.; Peterman, Paul H.; Lebo, Jon A.

1991-01-01

Sediments from four inshore industrial sites and a reference site in the Great Lakes were extracted with organic solvents to produce a crude extract, which was separated on alumina into two fractions: predominantly polycyclic aromatic hydrocarbons; and predominantly nitrogencontaining polycyclic aromatic compounds. Crude extracts were redissolved in acetone and analyzed by gas chromatography and gas chromatography-mass spectrometry. The acetone-redissolved crude extracts from the four industrialized sites contained 5.6–313.3 μg total polycyclic aromatic compounds/g sediment and 3.0–36.4 μg other compounds/g sediment. In addition to the typical EPA priority pollutants, a substantial amount (228.7 μg/g sediment) of alkyl-polycyclic-aromatic compounds was detected in sediments from one of the industrialized sites. Extracts from the reference site contained 1.55 μg total polycyclic aromatic compounds/ g sediment. Medaka (Oryzias latipes) were exposed to multiple pulse doses of acetone-redissolved extracts and fractions. Medaka were also exposed to a known carcinogen, methylazoxymethanol acetate, to verify that chemicals produced tumors in the test fish. Acetone-redissolved extracts and fractions from contaminated sediments were toxic to medaka. Fin erosion and non-neoplastic liver abnormalities were more prevalent in medaka after exposure to acetoneredissolved extracts and fractions from contaminated sediments. Neoplasms previously associated with chemical exposure in wild fishes were induced in medaka exposed to acetone-redissolved extracts and fractions from two of the contaminated sites, but not from the reference site or controls. These findings further support the hypothesis that chemical contaminants in sediments are involved in epizootics of neoplasms in wild fishes at contaminated sites.

The Aspergillus niger faeB gene encodes a second feruloyl esterase involved in pectin and xylan degradation and is specifically induced in the presence of aromatic compounds.

PubMed Central

de Vries, Ronald P; vanKuyk, Patricia A; Kester, Harry C M; Visser, Jaap

2002-01-01

The faeB gene encoding a second feruloyl esterase from Aspergillus niger has been cloned and characterized. It consists of an open reading frame of 1644 bp containing one intron. The gene encodes a protein of 521 amino acids that has sequence similarity to that of an Aspergillus oryzae tannase. However, the encoded enzyme, feruloyl esterase B (FAEB), does not have tannase activity. Comparison of the physical characteristics and substrate specificity of FAEB with those of a cinnamoyl esterase from A. niger [Kroon, Faulds and Williamson (1996) Biotechnol. Appl. Biochem. 23, 255-262] suggests that they are in fact the same enzyme. The expression of faeB is specifically induced in the presence of certain aromatic compounds, but not in the presence of other constituents present in plant-cell-wall polysaccharides such as arabinoxylan or pectin. The expression profile of faeB in the presence of aromatic compounds was compared with the expression of A. niger faeA, encoding feruloyl esterase A (FAEA), and A. niger bphA, the gene encoding a benzoate-p-hydroxylase. All three genes have different subsets of aromatic compounds that induce their expression, indicating the presence of different transcription activating systems in A. niger that respond to aromatic compounds. Comparison of the activity of FAEA and FAEB on sugar-beet pectin and wheat arabinoxylan demonstrated that they are both involved in the degradation of both polysaccharides, but have opposite preferences for these substrates. FAEA is more active than FAEB towards wheat arabinoxylan, whereas FAEB is more active than FAEA towards sugar-beet pectin. PMID:11931668

Microwave-assisted extraction of polycyclic aromatic compounds from coal.

PubMed

Kerst, M; Andersson, J T

2001-08-01

Microwave-assisted extraction (MAE) of polycyclic aromatic compounds (PACs) from coal is shown to give the same pattern of compounds as Soxhlet extraction. MAE requires only 10 mL solvent and 10 min extraction time whereas Soxhlet uses 200 mL and takes 24 h. Although the yields were lower, dichloromethane (DCM) was preferred to pyridine, N-methyl-2-pyrrolidone (NMP), and NMP with CS2 because the pattern of the PACs is shown to be independent of solvent and DCM is a much more convenient solvent to work with.

Organic composition of fogwater in the Texas-Louisiana gulf coast corridor

NASA Astrophysics Data System (ADS)

Raja, Suresh; Raghunathan, Ravikrishna; Kommalapati, Raghava R.; Shen, Xinhua; Collett, Jeffrey L.; Valsaraj, Kalliat T.

Fogwater and air samples were collected in Baton Rouge between November 2004-February 2005 and during February 2006 at Houston. Organic compounds present in the fog samples were detected, quantified and then grouped into different compound classes based on molecular size, solubility and polarity using gas chromatography/mass spectrometry, high performance liquid chromatography with diode array detection and ion chromatography. Organic compounds were grouped as n-alkanes, aromatics and polycyclic aromatics, carbonyls, alcohols, amides and esters. Organic compounds in fog and air samples in Houston indicated clear urban/industrial anthropogenic origin, while compounds detected in Baton Rouge fog and air samples showed a mix of both agricultural and urban/industrial anthropogenic inputs. Among the various polycyclic aromatic compounds detected, the total concentration of naphthalene and its derivatives was 2.8 μg m -3 in Houston and 0.08 μg m -3 in Baton Rouge air. Analysis of concentrations of organic compounds pre- and post- fog revealed that compounds with low vapor pressure had higher scavenging efficiency in fog sampled at the two locations. Concentrations of organic compounds in fog samples were higher than those predicted by conventional air-water Henry's law equilibrium. Observed higher concentrations in the aqueous phase were modeled accounting for surface adsorption and accumulation of gas phase species and the presence of humic-like substances in fogwater.

Comparative study of the affinity and metabolism of type I and type II binding quinoline carboxamide analogs by cytochrome P450 3A4

PubMed Central

Dahal, Upendra P.; Joswig-Jones, Carolyn; Jones, Jeffrey P.

2011-01-01

Compounds that coordinate to the heme-iron of cytochrome P450 (CYP) enzymes are assumed to increase metabolic stability. However, recently we observed that the type II binding quinoline carboxamide (QCA) compounds were metabolically less stable. To test if the higher intrinsic clearance of type II binding compounds relative to type I binding compounds is general for other metabolic transformations, we synthesized a library of QCA compounds that could undergo N-dealkylation, O-dealkylation, benzylic hydroxylation and aromatic hydroxylation. The results demonstrated that type II binding QCA analogs were metabolically less stable (2 to 12 fold) at sub-saturating concentration compared to type I binding counterparts for all the transformations. When the rates of different metabolic transformations between type I and type II binding compounds were compared, they were found to be in the order of N-demethylation>benzylic hydroxylation> O-demethylation> aromatic hydroxylation. Finally, for the QCA analogs with aza-heteroaromatic rings, we did not detect metabolism in aza-aromatic rings (pyridine, pyrazine, pyrimidine) indicating electronegativity of the nitrogen can change regioselectivity in CYP metabolism. PMID:22087535

INORGANIC COORDINATION POLYMERS. IV. THE ATTEMPTED REPLACEMENT OF ACETYLACETONATE LIGANDS WITH PICOLINATE LIGANDS,

DTIC Science & Technology

HETEROCYCLIC COMPOUNDS, PHOSPHENE OXIDES, BENZENE, CHROMIUM COMPOUNDS, CHEMICAL REAC, SYNTHESIS (CHEMISTRY), CHEMICAL ANALY, SPECTRA (INFRARED), ABSORPTION, DISPLACE, POLYMERIZATION, ORGANIC NITROGEN, AROMATIC COMPOUNDS.

Synthetic approaches to aromatic belts: building up strain in macrocyclic polyarenes.

PubMed

Eisenberg, David; Shenhar, Roy; Rabinovitz, Mordecai

2010-08-01

This tutorial review discusses synthetic strategies towards aromatic belts, defined here as double-stranded conjugated macrocycles, such as [n]cyclacenes, [n]cyclophenacenes, Schlüter belt, and Vögtle belt. Their appeal stems, firstly, from the unique nature of their conjugation, having p orbitals oriented radially rather than perpendicular to the plane of the macrocycle. Secondly, as aromatic belts are model compounds of carbon nanotubes of different chiralities, a synthetic strategy towards the buildup of structural strain in these compounds could finally open a route towards rational chemical synthesis of carbon nanotubes. The elusiveness of these compounds has stimulated fascinating and ingenious synthetic strategies over the last decades. The various strategies are classified here by their approach to the buildup of structural strain, which is the main obstacle in the preparation of these curved polyarenes.

Biotransformation of petroleum hydrocarbons and microbial communities in seawater with oil dispersions and copepod feces.

PubMed

Størdal, Ingvild Fladvad; Olsen, Anders Johny; Jenssen, Bjørn Munro; Netzer, Roman; Altin, Dag; Brakstad, Odd Gunnar

2015-12-30

To determine biotransformation of components in crude oil dispersions in the presence of feces from marine copepods, dispersed oil was incubated alone, with the addition of clean or oil-containing feces. We hypothesized that the feces would contribute with nutrients to bacteria, and higher concentrations of oil-degrading bacteria, respectively. Presence of clean feces resulted in higher degradation of aromatic oil compounds, but lower degradation of n-alkanes. Presence of oil-containing feces resulted in higher degradation of n-alkanes. The effect of clean feces on aromatic compounds are suggested to be due to higher concentrations of nutrients in the seawater where aromatic degradation takes place, while the lower degradation of n-alkanes are suggested to be due to a preference by bacteria for feces over these compounds. Large aggregates were observed in oil dispersions with clean feces, which may cause sedimentation of un-weathered lipophilic oil compounds towards the seafloor if formed during oil spills. Copyright © 2015 Elsevier Ltd. All rights reserved.

Spectroscopic study of proflavine adsorption on the carbon nanotube surface.

PubMed

Buchelnikov, Anatoly S; Dovbeshko, Galina I; Voronin, Dmitry P; Trachevsky, Vladimir V; Kostjukov, Viktor V; Evstigneev, Maxim P

2014-01-01

Despite the fact that non-covalent interactions between various aromatic compounds and carbon nanotubes are being extensively investigated now, there is still a lack of understanding about the nature of such interactions. The present paper sheds light on one of the possible mechanisms of interaction between the typical aromatic dye proflavine and the carbon nanotube surface, namely, π-stacking between aromatic rings of these compounds. To investigate such a complexation, a qualitative analysis was performed by means of ultraviolet visible, infrared, and nuclear magnetic resonance spectroscopy. The data obtained suggest that π-stacking brings the major contribution to the stabilization of the complex between proflavine and the carbon nanotube.

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.

Purification and characteristics of an inducible by polycyclic aromatic hydrocarbons NADP(+)-dependent naphthalenediol dehydrogenase (NDD) in Mucor circinelloides YR-1.

PubMed

Camacho-Morales, Reyna Lucero; Zazueta-Novoa, Vanesa; Casillas, Juana Lizbeth González; Ballesteros, Elizabeth Aranda; Bote, Juan Antonio Ocampo; Zazueta-Sandoval, Roberto

2014-05-01

We detected NADP(+)-dependent dihydrodiol dehydrogenase (DD) activity in a cell-free extract from Mucor circinelloides YR-1, after high-speed centrifugation. We analyzed the enzymatic activity in the cytosolic fraction by zymograms, as described previously, and eight different DD activity bands were revealed. Five constitutive DD activities (DD1-5) were present when glucose was used as carbon source and three inducible activities (NDD, PDD1 and PDD2) when aromatic hydrocarbon compounds were used. NDD activity was induced all of the aromatic hydrocarbon compounds. The highest DD activity inducer was naphthalene and the lowest was pyrene. One of the enzymes showed higher activity with cis-naphthalene-diol rather than with trans-nahthalenediol as a substrate. We purified this particular enzyme to homogeneity and found that it had an isoelectric point of 4.6. The molecular weight for the native protein was 197.4kDa and 49.03±0.5kDa for the monomer that conforms it, suggesting a homotetrameric structure for the complete enzyme. Polyclonal antibodies were raised against it and obtained. NDD activity was almost totally inhibited when antibodies were used at low concentrations, and in native immunoblots only one band, which corresponds to the activity band detected in the zymograms, could be detected. In denaturing PAGE immunoblots only one band was detected. This band corresponds to the purified protein band of 49kDa detected in SDS-PAGE gels. The other two inducible enzymes PDD1 and PDD2 were present only when phenanthrene was used as sole carbon source in the culture media. Copyright © 2014 Elsevier Inc. All rights reserved.

Polycyclic aromatic hydrocarbons in urban soil of Novi Sad, Serbia: occurrence and cancer risk assessment.

PubMed

Škrbić, Biljana D; Đurišić-Mladenović, Nataša; Tadić, Đorđe J; Cvejanov, Jelena Đ

2017-07-01

Contents of 16 polycyclic aromatic hydrocarbons were analyzed in 30 soil samples from 15 locations in Novi Sad, Serbia, assessing for the first time the corresponding health risks in the Serbian urban zone. Total concentrations were in the range of 22-2247 μg kg -1 , with a mean and median value of 363 and 200 μg kg -1 , respectively. Comparison with the relevant maximum allowed contents proposed by the Serbian government and with the Dutch target values implied that soils from the urban area of Novi Sad were "suitable as residential soils" and that no intervention would be needed if the current levels were retained. Seven diagnostic ratios were calculated, indicating the pyrogenic sources of PAHs as the dominant. Cancer risks in humans via accidental ingestion, inhalation of soil particles, and dermal contact with soil were estimated. Cancer risk for soil ingestion by children was the highest. The total lifetime carcinogenic risk as sum of individual cancer risks for seven carcinogenic polycyclic aromatic hydrocarbons was within the range 10 -4 to 10 -6 , indicating acceptable risks at 30 and 47% of sites for children and adults, respectively. However, for the rest of the samples, total lifetime cancer risk was >10 -4 indicating over the acceptable risk, even though the contents in soil were not of concern as the comparison with the environmental guidance previously showed. This could be explained by (a) the dominant concentrations of higher molecular weight compounds with 4 to 6 rings, among which there are compounds with higher toxicity equivalents, but also with (b) the extreme conditions used for the conservative risk assessment under maximal exposure frequency, exposure time, and ingestion rates.

Reductive deconstruction of organosolv lignin catalyzed by zeolite supported nickel nanoparticles

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kasakov, Stanislav; Shi, Hui; Camaioni, Donald M.

2015-11-01

Mechanistic aspects of deconstruction and hydrodeoxygenation of organosolv lignin using supported Ni catalysts with (Ni/HZSM-5 and Ni/HBEA) and without Brønsted acid sites (Ni/SiO2) are reported. Lignin was deconstructed and converted to saturated cyclic hydrocarbons ranging from C5 to C14. In the one-stage reaction, full conversion with total yield of 70 ± 5 wt.% saturated hydrocarbons was achieved at 593 K and 20 bar H2. The organosolv lignin used consists of seven to eight monolignol subunits and has an average molecular weight of ca. 1200 g mol-1. The monolignols were mainly guaiacyl, syringyl and phenylcoumaran, randomly interconnected through β-O-4, 4-O-5, β-1,more » 5-5’ and β-β ether bonds. In situ IR spectroscopy was used to follow the changes in lignin constituents during reaction. The proposed reaction pathways for the catalytic transformation of this organosolv lignin to alkanes start with the hydrogenolysis of aryl alkyl ether bonds, followed by hydrogenation of the aromatic compounds on Ni to cyclic alcohols. Oxygen is removed from the alcohols via dehydration on Brønsted acid sites to yield cyclic alkenes that are further hydrogenated to alkanes. Formation of condensation products may occur via intermolecular recombination of aromatic monomers or alkylation of aromatic compounds by alkenes. The financial support from TUM-PNNL cooperation project “Development of new methods for in situ characterization in liquid phase reactions” (CN-177939) is highly appreciated. The work by S.K., H.S., and J.A.L was partially supported by the US Department of Energy, Office of Science, Office of Basic Energy Sciences, Division of Chemical Sciences, Geosciences, and Biosciences.« less

[Preliminary determination of organic pollutants in agricultural fertilizers].

PubMed

Mo, Ce-hui; Li, Yun-hui; Cai, Quan-ying; Zeng, Qiao-yun; Wang, Bo-guang; Li, Hai-qin

2005-05-01

Organic pollutants such as polycyclic aromatic hydrocarbons (PAHs) in agricultural fertilizers are new problem deserved more study. Eight kinds of organic pollutants including 43 compounds classified as US EPA priority pollutants in twenty one agricultural fertilizers which were universally used in China were determined by Gas chromatography-mass spectrum (GC-MS). Three kinds of organic pollutants including more than 5 compounds were detected in most fertilizers, composing mainly of phthalic acid esters (PAEs), nitrobenzenes (NBs) and polycyclic aromatic hydrocarbons (PAHs). There were 26 compounds detected in at least one fertilizer, five of them especially PAEs detected in most fertilizer and even in all fertilizers. Benzo(a)pyrene, a strongly carcinogenic compound was detected in two fertilizers. Higher concentrations of compounds were determined in those fertilizers such as multifunction compound fertilizers and coated fertilizers.

Protonation at the aromatic ring of samarium benzophenone dianion species. Isolation and structural characterization of a samarium(III) enolate complex

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hou, Z.; Yoshimura, Takashi; Wakatsuki, Yasuo

1994-11-30

The reduction of aromatic compounds into their dihydro derivatives by dissolving metal/alcohol systems (the Birch reduction) is a useful methodology in organic synthesis. Of particular importance is the reduction of aromatic carbonyl compounds such as aromatic acids, esters, amides, and monoaryl ketones, which usually generates in situ useful metal enolate intermediates that upon further reaction with electrophiles yield a variety of cyclohexadiene derivatives. One of the possible processes to generate these metal enolate intermediates is thought to be the monoprotonation of dianionic species at the para position of the aromatic rings. On the other hand, the reduction of diaryl ketonesmore » by alkali metals in liquid ammonia or by lanthanide metals in THF/HMPA or DME has been well known to afford the corresponding ketone dianions. The first X-ray structure of metal ketone dianion complexes, [Yb([mu]-[eta][sup 1],[eta][sup 2]-OCPh[sub 2]) (HMPA)[sub 2

Metal Triflates for the Production of Aromatics from Lignin.

PubMed

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

2016-10-20

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

Aromatic derivatives of 1H-2,3-dihydropyrazolo(4,5-b)-1,5-diazepine

DOE Office of Scientific and Technical Information (OSTI.GOV)

Orlov, V.D.; Kiroga, Kh.; Kolos, N.N.

1987-09-01

Aromatic derivatives of 1H-2,3-dihydropyrazole(4,5-b)-1,5-diazepine were obtained by the reaction of 1-phenyl-3-methyl-4,5-diaminopyrazole with chalcones and acetylarenes, catalyzed by acetic or sulfuric acid. The seven-membered ring in these compounds has a conformation of the boat type. The IR, UV, PMR, and mass spectra of the compounds are discussed.

Sorption of the Aircraft Deicing Fluid Component Methyl-Benzotriazole in Soil

DTIC Science & Technology

1999-03-01

Atlas , Ronald M., Bartha , Richard, Microbial Ecology : Fundamentals and Applications. Benjamin Cummings: Redwood City, 1993. Ball, William P., Roberts...cell; transfer of substances from one medium to another [ Atlas and Bartha , 533; Fetter, 117]. (2) The process by which a compound in solution or...oxygen, low redox potential. [ Atlas and Bartha , 534; Schwarzenbach et al, 410] Aromatic compound - Carbon skeletons containing aromatic benzene ring and

Al-based metal-organic gels for selective fluorescence recognition of hydroxyl nitro aromatic compounds

NASA Astrophysics Data System (ADS)

Guo, Mao Xia; Yang, Liu; Jiang, Zhong Wei; Peng, Zhe Wei; Li, Yuan Fang

2017-12-01

The novel class of luminescent Al3 +-based metal-organic gels (Al-MOGs) have been developed by mix 4-[2,2‧:6‧,2″-terpyridine]-4‧-ylbenzoic acid (Hcptpy) with Al3 + under mild condition. The as-prepared Al-MOGs have not only multiple stimuli-responsive properties, but selective recognition of hydroxyl nitro aromatic compounds, which can quench the fluorescence of the Al-MOGs, while other nitro aromatic analogues without hydroxyl substitutes cannot. The fluorescence of Al-MOGs at 467 nm was seriously quenched by picric acid (PA) whose lowest unoccupied molecular orbital (LUMO) energy levels are lower than those of three other hydroxyl nitro aromatic compounds including 4-nitrophenol (4-NP), 3,5-dinitrosalicylic acid (3,5-DNTSA) and 2,4-dinitrophenol (2,4-DNP). Thus, PA was chosen as a model compound under optimal conditions and the relative fluorescence intensity of Al-MOGs was proportional to the concentration of PA in the range of 5.0-320.0 μM with a detection limit of 4.64 μM. Furthermore, the fluorescence quenching mechanism has also been investigated and revealed that the quenching was attributed to inner filter effects (IFEs), as well as electron transfer (ET) between Al-MOGs and PA.

Al-based metal-organic gels for selective fluorescence recognition of hydroxyl nitro aromatic compounds.

PubMed

Guo, Mao Xia; Yang, Liu; Jiang, Zhong Wei; Peng, Zhe Wei; Li, Yuan Fang

2017-12-05

The novel class of luminescent Al 3+ -based metal-organic gels (Al-MOGs) have been developed by mix 4-[2,2':6',2″-terpyridine]-4'-ylbenzoic acid (Hcptpy) with Al 3+ under mild condition. The as-prepared Al-MOGs have not only multiple stimuli-responsive properties, but selective recognition of hydroxyl nitro aromatic compounds, which can quench the fluorescence of the Al-MOGs, while other nitro aromatic analogues without hydroxyl substitutes cannot. The fluorescence of Al-MOGs at 467nm was seriously quenched by picric acid (PA) whose lowest unoccupied molecular orbital (LUMO) energy levels are lower than those of three other hydroxyl nitro aromatic compounds including 4-nitrophenol (4-NP), 3,5-dinitrosalicylic acid (3,5-DNTSA) and 2,4-dinitrophenol (2,4-DNP). Thus, PA was chosen as a model compound under optimal conditions and the relative fluorescence intensity of Al-MOGs was proportional to the concentration of PA in the range of 5.0-320.0μM with a detection limit of 4.64μM. Furthermore, the fluorescence quenching mechanism has also been investigated and revealed that the quenching was attributed to inner filter effects (IFEs), as well as electron transfer (ET) between Al-MOGs and PA. Copyright © 2017 Elsevier B.V. All rights reserved.

Water-Quality Constituents, Dissolved-Organic-Carbon Fractions, and Disinfection By-Product Formation in Water from Community Water-Supply Wells in New Jersey, 1998-99

USGS Publications Warehouse

Hopple, Jessica A.; Barringer, Julia L.; Koleis, Janece

2007-01-01

Water samples were collected from 20 community water-supply wells in New Jersey to assess the chemical quality of the water before and after chlorination, to characterize the types of organic carbon present, and to determine the disinfection by-product formation potential. Water from the selected wells previously had been shown to contain concentrations of dissolved organic carbon (DOC) that were greater than 0.2 mg/L. Of the selected wells, five are completed in unconfined (or semi-confined) glacial-sediment aquifers of the Piedmont and Highlands (New England) Physiographic Provinces, five are completed in unconfined bedrock aquifers of the Piedmont Physiographic Province, and ten are completed in unconsolidated sediments of the Coastal Plain Physiographic Province. Four of the ten wells in the Coastal Plain are completed in confined parts of the aquifers; the other six are in unconfined aquifers. One or more volatile organic compounds (VOCs) were detected in untreated water from all of the 16 wells in unconfined aquifers, some at concentrations greater than maximum contaminant levels. Those compounds detected included aliphatic compounds such as trichloroethylene and 1,1,1-trichloroethane, aromatic compounds such as benzene, the trihalomethane compound, chloroform, and the gasoline additive methyl tert-butyl ether (MTBE). Concentrations of sodium and chloride in water from one well in a bedrock aquifer and sulfate in water from another exceeded New Jersey secondary standards for drinking water. The source of the sulfate was geologic materials, but the sodium and chloride probably were derived from human inputs. DOC fractions were separated by passing water samples through XAD resin columns to determine hydrophobic fractions from hydrophilic fractions. Concentrations of hydrophobic acids were slightly lower than those of combined hydrophilic acids, neutral compounds, and low molecular weight compounds in most samples. Water samples from the 20 wells were adjusted to a pH of 7, dosed with sodium hypochlorite, and incubated for 168 hours (seven days) at 25 ?C to form disinfection by-products (DBPs). Concentrations of the DBPs-trihalomethanes, haloacetic acids, haloacetonitriles, and chlorate-were measured. Concentrations of these compounds, with few exceptions, were higher in water from Coastal Plain wells than from wells in glacial and bedrock aquifers. The organic-carbon fractions were dosed with sodium hypochlorite, incubated for 168 hours at 25 ?C, and analyzed for trihalomethanes, haloacetic acids, haloacetonitriles, and chlorate. Concentrations of trihalomethanes and haloacetic acids were higher in most of the hydrophobic organic-acid fractions than in the hydrophilic fractions, with the highest concentrations in samples from Coastal Plain aquifers. Traces of haloacetonitriles were measured, mostly in the hydrophilic fraction. The aromaticity of the precursor DOC, as estimated by measurements of the absorbance of ultraviolet light at 254 nanometers, apparently is a factor in the DBP formation potentials determined, as aromaticity was greater in the samples that developed high concentrations of DBPs. VOCs may have contributed to the organic carbon present in some of the samples, but much of the DOC present in water from the 20 wells appeared to be natural in origin. The sediments of the Coastal Plain aquifers, in particular, contain substantial amounts of organic matter, which contribute ammonia, organic nitrogen, and aromatic DOC compounds to the ground water. Thus, the geologic characteristics of the aquifers appear to be a major factor in the potential for ground water to form DBPs when chlorinated.

Evaluating Activated Carbon Adsorption of Dissolved Organic Matter and Micropollutants Using Fluorescence Spectroscopy.

PubMed

Shimabuku, Kyle K; Kennedy, Anthony M; Mulhern, Riley E; Summers, R Scott

2017-03-07

Dissolved organic matter (DOM) negatively impacts granular activated carbon (GAC) adsorption of micropollutants and is a disinfection byproduct precursor. DOM from surface waters, wastewater effluent, and 1 kDa size fractions were adsorbed by GAC and characterized using fluorescence spectroscopy, UV-absorption, and size exclusion chromatography (SEC). Fluorescing DOM was preferentially adsorbed relative to UV-absorbing DOM. Humic-like fluorescence (peaks A and C) was selectively adsorbed relative to polyphenol-like fluorescence (peaks T and B) potentially due to size exclusion effects. In the surface waters and size fractions, peak C was preferentially removed relative to peak A, whereas the reverse was found in wastewater effluent, indicating that humic-like fluorescence is associated with different compounds depending on DOM source. Based on specific UV-absorption (SUVA), aromatic DOM was preferentially adsorbed. The fluorescence index (FI), if interpreted as an indicator of aromaticity, indicated the opposite but exhibited a strong relationship with average molecular weight, suggesting that FI might be a better indicator of DOM size than aromaticity. The influence of DOM intermolecular interactions on adsorption were minimal based on SEC analysis. Fluorescence parameters captured the impact of DOM size on the fouling of 2-methylisoborneol and warfarin adsorption and correlated with direct competition and pore blockage indicators.

Organic compounds in produced waters from coalbed natural gas wells in the Powder River Basin, Wyoming, USA

USGS Publications Warehouse

Orem, W.H.; Tatu, C.A.; Lerch, H.E.; Rice, C.A.; Bartos, T.T.; Bates, A.L.; Tewalt, S.; Corum, M.D.

2007-01-01

The organic composition of produced water samples from coalbed natural gas (CBNG) wells in the Powder River Basin, WY, sampled in 2001 and 2002 are reported as part of a larger study of the potential health and environmental effects of organic compounds derived from coal. The quality of CBNG produced waters is a potential environmental concern and disposal problem for CBNG producers, and no previous studies of organic compounds in CBNG produced water have been published. Organic compounds identified in the produced water samples included: phenols, biphenyls, N-, O-, and S-containing heterocyclic compounds, polycyclic aromatic hydrocarbons (PAHs), aromatic amines, various non-aromatic compounds, and phthalates. Many of the identified organic compounds (phenols, heterocyclic compounds, PAHs) are probably coal-derived. PAHs represented the group of organic compounds most commonly observed. Concentrations of total PAHs ranged up to 23 ??g/L. Concentrations of individual compounds ranged from about 18 to <0.01 ??g/L. Temporal variability of organic compound concentrations was documented, as two wells with relatively high organic compound contents in produced water in 2001 had much lower concentrations in 2002. In many areas, including the PRB, coal strata provide aquifers for drinking water wells. Organic compounds observed in produced water are also likely present in drinking water supplied from wells in the coal. Some of the organic compounds identified in the produced water samples are potentially toxic, but at the levels measured in these samples are unlikely to have acute health effects. The human health effects of low-level, chronic exposure to coal-derived organic compounds in drinking water are currently unknown. Continuing studies will evaluate possible toxic effects from low level, chronic exposure to coal-derived organic compounds in drinking water supplies.

University and Secondary School Students' Misconceptions about the Concept of "Aromaticity" in Organic Chemistry

ERIC Educational Resources Information Center

Topal, Giray; Oral, Behcet; Ozden. Mustafa

2007-01-01

Aromaticity concept is given incorrect or incomplete to the student in secondary education and knowledge based on this basic concept has been caused to another misconception in future. How are the achievement levels relating to the comprehension of various characteristics of aromatic compounds for the first and third grade students attending…

Two novel aromatic glucosides, marylaurencinosides D and E, from the fresh flowers of Cymbidium Great Flower 'Marylaurencin'.

PubMed

Yoshikawa, Kazuko; Okahuji, Mariko; Iseki, Kanako; Ito, Takuya; Asakawa, Yoshinori; Kawano, Sachiko; Hashimoto, Toshihiro

2014-04-01

Two novel aromatic glucosides, named marylaurencinosides D (1) and E (2), were isolated from the fresh flowers of Cymbidium Great Flower 'Marylaurencin'. In addition, eight known aromatic compounds (3-10) were isolated. These structures were determined on the basis of NMR experiments as well as chemical evidence.

Doped polycyclic aromatic hydrocarbons as building blocks for nanoelectronics: a theoretical study.

PubMed

Dral, Pavlo O; Kivala, Milan; Clark, Timothy

2013-03-01

Density functional theory (DFT) and semiempirical UHF natural orbital configuration interaction (UNO-CI) calculations are used to investigate the effect of heteroatom substitution at the central position of a model polycyclic aromatic hydrocarbon. The effects of the substitution on structure, strain, electronic and spectral properties, and aromaticity of the compounds are discussed.

Profile distribution of polycyclic aromatic hydrocarbons in soils of drained peatlands after wildfires (Moscow region, Russia)

NASA Astrophysics Data System (ADS)

Tsibart, Anna; Gennadiev, Alexander; Koshovskii, Timur; Kovach, Roman

2014-05-01

Polycyclic aromatic compounds (PAHs) are formed in different natural and anthropogenic processes and could be found in many landscape components. These compounds are carcinogenic and belong to the group of persistent organic pollutants. The anthropogenic sources of PAHs are well-studied, but insufficient data are available on the hightemperature production of PAHs in natural processes. For example, natural fires are frequently related to the PAHs sources in landscapes, but very little factual data are on this topic. The soils of drained peatlands affected by catastrophic wildfires of 2010 and 2002 were studied in the Eastern part of Moscow Region (Russia). A total of 14 profiles of histosols and histic podsols were investigated. These series included soils of plots subjected to fires of different intensities and age, as well as soils of the background plots. Soil samples were taken from genetic horizons and from every 10 cm. The samples were analyzed for the contents of 14 prevailing individual compounds: fluorene, naphthalene, phenanthrene, chrysene, pyrene, anthracene, tetraphene, benz[a]pyrene, benzo[ghi]perylene, benzo[e]pyrene, coronene, dibenztiophene, triphenilene, benz(k)fluorantene. Morfological properties of soils after wildfires on drained peatlands were changed dramatically, the horizons of ash and char instead of organic layers were formed. These new horizons differ in the capability of PAHs accumulation. The char horizons have the highest concentrations of PAHs - up to 300 ng/g because of incomplete burning of organic matter in this sites, and the ash horizons, where the complete burning occured, contain only 10 ng/g PAHs. The highest concentrations of PAHs in soil profiles were detected after recent fires, and in cases of thick peat layers. After the combustion of peat chrysene, benz[a]pyrene, benz[e]pyrene, benzo[ghi]perylene, benz(k)fluorantene and tetraphene accumulated in soils. This is mainly the group of 4-6-nuclear compounds. The formation of high-molecular weight compounds is possible during smoldering process under a low oxygen supply. The oxygen deficit acts as a factor of the organic fragments recombination and PAHs production; therefore, relatively large amounts of PAHs are formed in peat fires. Moreover the peat fires occur directly in the soil layer; therefore, larger amounts of the resulting PAHs remain in the soils of the fire sites. The migration of low-molecular weight compounds occures in histic podsols, in histosols PAHs accumalate only in upper organic horizons. The research was conducted with the support of Russian Geographical Society.

Water-quality data of stormwater runoff from Davenport, Iowa, 1992 and 1994

USGS Publications Warehouse

Schaap, B.D.; Einhellig, R.F.

1996-01-01

During 1992 and 1994, stormwater runoff in Davenport, Iowa, was sampled from the following land use types: agricultural and vacant, residential, commercial, parks and wooded areas, and industrial. Grab samples collected within the first hour of the runoff event were analyzed for many constituents including volatile organic compounds. Flow-weighted composite samples, composed from discrete samples collected at 15-minute intervals during the first three hours of the event or until discharge returned to pre-event levels, also were analyzed for many constituents including major ions, nitrogen, phosphorus, metals, total organic carbon, acid/base-neutral organics, organochlorine pesticides, and polycyclic aromatic hydrocarbons.

Colonic catabolism of dietary phenolic and polyphenolic compounds from Concord grape juice.

PubMed

Stalmach, Angelique; Edwards, Christine A; Wightman, Jolynne D; Crozier, Alan

2013-01-01

After acute ingestion of 350 ml of Concord grape juice, containing 528 μmol of (poly)phenolic compounds, by healthy volunteers, a wide array of phase I and II metabolites were detected in the circulation and excreted in urine. Ingestion of the juice by ileostomists resulted in 40% of compounds being recovered intact in ileal effluent. The current study investigated the fate of these undigested (poly)phenolic compounds on reaching the colon. This was achieved through incubation of the juice using an in vitro model of colonic fermentation and through quantification of catabolites produced after colonic degradation and their subsequent absorption prior to urinary excretion by healthy subjects and ileostomy volunteers. A total of 16 aromatic and phenolic compounds derived from colonic metabolism of Concord grape juice (poly)phenolic compounds were identified by GC-MS in the faecal incubation samples. Thirteen urinary phenolic acids and aromatic compounds were excreted in significantly increased amounts after intake of the juice by healthy volunteers, whereas only two of these compounds were excreted in elevated amounts by ileostomists. The production of phenolic acids and aromatic compounds by colonic catabolism contributed to the bioavailability of Concord grape (poly)phenolic compounds to a much greater extent than phase I and II metabolites originating from absorption in the upper gastrointestinal tract. Catabolic pathways are proposed, highlighting the impact of colonic microbiota and subsequent phase II metabolism prior to excretion of phenolic compounds derived from (poly)phenolic compounds in Concord grape juice, which pass from the small to the large intestine.

Binding of pyrene to aquatic and commercial humic substances: The role of molecular weight and aromaticity

USGS Publications Warehouse

Chin, Y.-P.; Aiken, G.R.; Danielsen, K.M.

1997-01-01

The binding of pyrene to a number of humic substances isolated from various aquatic sources and a commercial humic acid was measured using the solubility enhancement method. The humic materials used in this study were characterized by various spectroscopic and liquid chromatography methods. A strong correlation was observed between the pyrene binding coefficient, K(doc), and the molecular weights, molar absorptivities at 280 nm, and aromaticity of the aquatic humic substances. Binding of pyrene to the commercial humic acid, however, was significantly stronger and did not obey the relationships observed between K(doc) and the chemical properties of the aquatic humic substrates. These results suggest that the molecular weight and the aromatic content of the humic substrates exert influences on the binding of nonpolar and planar aromatic molecules and that the physicochemical properties of both humic materials and organic solutes are important in controlling the speciation of nonpolar organic contaminants in natural waters.

Application of Atmospheric Solids Analysis Probe Mass Spectrometry (ASAP-MS) in Petroleomics: Analysis of Condensed Aromatics Standards, Crude Oil, and Paraffinic Fraction.

PubMed

Tose, Lilian V; Murgu, Michael; Vaz, Boniek G; Romão, Wanderson

2017-11-01

Atmospheric solids analysis probe mass spectrometry (ASAP-MS) is a powerful tool for analysis of solid and liquid samples. It is an excellent alternative for crude oil analysis without any sample preparation step. Here, ASAP-MS in positive ion mode, ASAP(+)-MS, has been optimized for analysis of condensed aromatics (CA) standards, crude oil, and paraffinic fraction samples using a Synapt G2-S HDMS. Initially, two methodologies were used to access the chemical composition of samples: (1) using a temperature gradient varying from 150 to 600 °C at a heating rate of 150 °C min -1 , and (2) with constant temperature of 300 and 400 °C. ASAP(+)-MS ionized many compounds with a typical petroleum profile, showing a greater signals range of m/z 250-1300 and 200-1400 for crude oil and paraffin samples, respectively. Such performance, mainly related to the detection of high molecular weight compounds (>1000 Da), is superior to that of other traditional ionization sources, such as ESI, APCI, DART, and DESI. Additionally, the CA standards were identified in both forms: radicals, [M] +• , and protonated cations, [M + H] + , with minimum fragmentation. Therefore, ASAP was more efficient in accessing the chemical composition of nonpolar and polar compounds. It is promising in its application with ultrahigh resolution MS instruments, such as FT-ICR MS and Orbitrap, since molecular formulas with greater resolution and mass accuracy (<1 ppm) would be assigned. Graphical Abstract ᅟ.

Application of Atmospheric Solids Analysis Probe Mass Spectrometry (ASAP-MS) in Petroleomics: Analysis of Condensed Aromatics Standards, Crude Oil, and Paraffinic Fraction

NASA Astrophysics Data System (ADS)

Tose, Lilian V.; Murgu, Michael; Vaz, Boniek G.; Romão, Wanderson

2017-08-01

Atmospheric solids analysis probe mass spectrometry (ASAP-MS) is a powerful tool for analysis of solid and liquid samples. It is an excellent alternative for crude oil analysis without any sample preparation step. Here, ASAP-MS in positive ion mode, ASAP(+)-MS, has been optimized for analysis of condensed aromatics (CA) standards, crude oil, and paraffinic fraction samples using a Synapt G2-S HDMS. Initially, two methodologies were used to access the chemical composition of samples: (1) using a temperature gradient varying from 150 to 600 °C at a heating rate of 150 °C min-1, and (2) with constant temperature of 300 and 400 °C. ASAP(+)-MS ionized many compounds with a typical petroleum profile, showing a greater signals range of m/z 250-1300 and 200-1400 for crude oil and paraffin samples, respectively. Such performance, mainly related to the detection of high molecular weight compounds (>1000 Da), is superior to that of other traditional ionization sources, such as ESI, APCI, DART, and DESI. Additionally, the CA standards were identified in both forms: radicals, [M]+•, and protonated cations, [M + H]+, with minimum fragmentation. Therefore, ASAP was more efficient in accessing the chemical composition of nonpolar and polar compounds. It is promising in its application with ultrahigh resolution MS instruments, such as FT-ICR MS and Orbitrap, since molecular formulas with greater resolution and mass accuracy (<1 ppm) would be assigned. [Figure not available: see fulltext.

Safety in the Chemical Laboratory: Nitric Acid, Nitrates, and Nitro Compounds.

ERIC Educational Resources Information Center

Bretherick, Leslie

1989-01-01

Discussed are the potential hazards associated with nitric acid, inorganic and organic nitrate salts, alkyl nitrates, acyl nitrates, aliphatic nitro compounds, aromatic nitro compounds, and nitration reactions. (CW)

Determination of Aromatic Ring Number Using Multi-Channel Deep UV Native Fluorescence

NASA Technical Reports Server (NTRS)

Bhartia, R.; McDonald, G. D.; Salas, E.; Conrad, P.

2004-01-01

The in situ detection of organic material on an extraterrestrial surface requires both effective means of searching a relatively large surface area or volume for possible organic carbon, and a more specific means of identifying and quantifying compounds in indicated samples. Fluorescence spectroscopy fits the first requirement well, as it can be carried out rapidly, with minimal or no physical contact with the sample, and with sensitivity unmatched by any other organic analytical technique. Aromatic organic compounds with know fluorescence signatures have been identified in several extraterrestrial samples, including carbonaceous chondrites, interplanetary dust particles, and Martian meteorites. The compound distributions vary among these sources, however, with clear differences in relative abundances by number of aromatic rings and by degree of alkylation. This relative abundance information, therefore, can be used to infer the source of organic material detected on a planetary surface.

Synthesis and biological evaluation of novel bis-aromatic amides as novel PTP1B inhibitors.

PubMed

Wang, Wen-Long; Huang, Chao; Gao, Li-Xin; Tang, Chun-Lan; Wang, Jun-Qing; Wu, Min-Chen; Sheng, Li; Chen, Hai-Jun; Nan, Fa-Jun; Li, Jing-Ya; Li, Jia; Feng, Bainian

2014-04-15

A series of bis-aromatic amides was designed, synthesized, and evaluated as a new class of inhibitors with IC50 values in the micromolar range against protein tyrosine phosphatase 1B (PTP1B). Among them, compound 15 displayed an IC50 value of 2.34±0.08 μM with 5-fold preference over TCPTP. More importantly, the treatment of CHO/HIR cells with compound 15 resulted in increased phosphorylation of insulin receptor (IR), which suggested extensive cellular activity of compound 15. These results provided novel lead compounds for the design of inhibitors of PTP1B as well as other PTPs. Copyright © 2014 Elsevier Ltd. All rights reserved.

Application of capillary gas chromatography mass spectrometry/computer techniques to synoptic survey of organic material in bed sediment

USGS Publications Warehouse

Steinheimer, T.R.; Pereira, W.E.; Johnson, S.M.

1981-01-01

A bed sediment sample taken from an area impacted by heavy industrial activity was analyzed for organic compounds of environmental significance. Extraction was effected on a Soxhlet apparatus using a freeze-dried sample. The Soxhlet extract was fractionated by silica gel micro-column adsorption chromatography. Separation and identification of the organic compounds was accomplished by capillary gas chromatography/mass spectrometry techniques. More than 50 compounds were identified; these include saturated hydrocarbons, olefins, aromatic hydrocarbons, alkylated polycyclic aromatic hydrocarbons, and oxygenated compounds such as aldehydes and ketones. The role of bed sediments as a source or sink for organic pollutants is discussed. ?? 1981.

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.

Occupational health and safety assessment of exposure to jet fuel combustion products in air medical transport.

PubMed

MacDonald, Russell D; Thomas, Laura; Rusk, Frederick C; Marques, Shauna D; McGuire, Dan

2010-01-01

Transport medicine personnel are potentially exposed to jet fuel combustion products. Setting-specific data are required to determine whether this poses a risk. This study assessed exposure to jet fuel combustion products, compared various engine ignition scenarios, and determined methods to minimize exposure. The Beechcraft King Air B200 turboprop aircraft equipped with twin turbine engines, using a kerosene-based jet fuel (Jet A-1), was used to measure products of combustion during boarding, engine startup, and flight in three separate engine start scenarios ("shielded": internal engine start, door closed; "exposed": ground power unit start, door open; and "minimized": ground power unit right engine start, door open). Real-time continuous monitoring equipment was used for oxygen, carbon dioxide, carbon monoxide, nitrogen dioxide, hydrogen sulfide, sulfur dioxide, volatile organic compounds, and particulate matter. Integrated methods were used for aldehydes, polycyclic aromatic hydrocarbons, volatile organic compounds, and aliphatic hydrocarbons. Samples were taken in the paramedic breathing zone for approximately 60 minutes, starting just before the paramedics boarded the aircraft. Data were compared against regulated time-weighted exposure thresholds to determine the presence of potentially harmful products of combustion. Polycyclic aromatic hydrocarbons, aldehydes, volatile organic compounds, and aliphatic hydrocarbons were found at very low concentrations or beneath the limits of detection. There were significant differences in exposures to particulates, carbon monoxide, and total volatile organic compound between the "exposed" and "minimized" scenarios. Elevated concentrations of carbon monoxide and total volatile organic compounds were present during the ground power unit-assisted dual-engine start. There were no appreciable exposures during the "minimized" or "shielded" scenarios. Air medical personnel exposures to jet fuel combustion products were generally low and did not exceed established U.S. or Canadian health and safety exposure limits. Avoidance of ground power unit-assisted dual-engine starts and closing the hangar door prior to start minimize or eliminate the occupational exposure.

Theoretical and experimental study of polycyclic aromatic compounds as β-tubulin inhibitors.

PubMed

Olazarán, Fabian E; García-Pérez, Carlos A; Bandyopadhyay, Debasish; Balderas-Rentería, Isaias; Reyes-Figueroa, Angel D; Henschke, Lars; Rivera, Gildardo

2017-03-01

In this work, through a docking analysis of compounds from the ZINC chemical library on human β-tubulin using high performance computer cluster, we report new polycyclic aromatic compounds that bind with high energy on the colchicine binding site of β-tubulin, suggesting three new key amino acids. However, molecular dynamic analysis showed low stability in the interaction between ligand and receptor. Results were confirmed experimentally in in vitro and in vivo models that suggest that molecular dynamics simulation is the best option to find new potential β-tubulin inhibitors. Graphical abstract Bennett's acceptance ratio (BAR) method.

Tough, high performance, addition-type thermoplastic polymers

NASA Technical Reports Server (NTRS)

Pater, Ruth H. (Inventor)

1992-01-01

A tough, high performance polyimide is provided by reacting a triple bond conjugated with an aromatic ring in a bisethynyl compound with the active double bond in a compound containing a double bond activated toward the formation of a Diels-Adler type adduct, especially a bismaleimide, a biscitraconimide, or a benzoquinone, or mixtures thereof. Addition curing of this product produces a high linear polymeric structure and heat treating the highly linear polymeric structure produces a thermally stable aromatic addition-type thermoplastic polyimide, which finds utility in the preparation of molding compounds, adhesive compositions, and polymer matrix composites.

Alkyne Benzannulation Reactions for the Synthesis of Novel Aromatic Architectures.

PubMed

Hein, Samuel J; Lehnherr, Dan; Arslan, Hasan; J Uribe-Romo, Fernando; Dichtel, William R

2017-11-21

Aromatic compounds and polymers are integrated into organic field effect transistors, light-emitting diodes, photovoltaic devices, and redox-flow batteries. These compounds and materials feature increasingly complex designs, and substituents influence energy levels, bandgaps, solution conformation, and crystal packing, all of which impact performance. However, many polycyclic aromatic hydrocarbons of interest are difficult to prepare because their substitution patterns lie outside the scope of current synthetic methods, as strategies for functionalizing benzene are often unselective when applied to naphthalene or larger systems. For example, cross-coupling and nucleophilic aromatic substitution reactions rely on prefunctionalized arenes, and even directed metalation methods most often modify positions near Lewis basic sites. Similarly, electrophilic aromatic substitutions access single regioisomers under substrate control. Cycloadditions provide a convergent route to densely functionalized aromatic compounds that compliment the above methods. After surveying cycloaddition reactions that might be used to modify the conjugated backbone of poly(phenylene ethynylene)s, we discovered that the Asao-Yamamoto benzannulation reaction is notably efficient. Although this reaction had been reported a decade earlier, its scope and usefulness for synthesizing complex aromatic systems had been under-recognized. This benzannulation reaction combines substituted 2-(phenylethynyl)benzaldehydes and substituted alkynes to form 2,3-substituted naphthalenes. The reaction tolerates a variety of sterically congested alkynes, making it well-suited for accessing poly- and oligo(ortho-arylene)s and contorted hexabenzocoronenes. In many cases in which asymmetric benzaldehyde and alkyne cycloaddition partners are used, the reaction is regiospecific based on the electronic character of the alkyne substrate. Recognizing these desirable features, we broadened the substrate scope to include silyl- and halogen-substituted alkynes. Through a combined experimental and computational approach, we have elucidated mechanistic insight and key principles that govern the regioselectivity outcome of the benzannulation of structurally diverse alkynes. We have applied these methods to prepare sterically hindered, shape-persistent aromatic systems, heterocyclic aromatic compounds, functionalized 2-aryne precursors, polyheterohalogenated naphthalenes, ortho-arylene foldamers, and graphene nanoribbons. As a result of these new synthetic avenues, aromatic structures with interesting properties were uncovered such as ambipolar charge transport in field effect transistors based on our graphene nanoribbons, conformational aspects of ortho-arylene architectures resulting from intramolecular π-stacking, and modulation of frontier molecular orbitals via protonation of heteroatom containing aromatic systems. Given the availability of many substituted 2-(phenylethynyl)benzaldehydes and the regioselectivity of the benzannulation reaction, naphthalenes can be prepared with control of the substitution pattern at seven of the eight substitutable positions. Researchers in a range of fields are likely to benefit directly from newly accessible molecular and polymeric systems derived from polyfunctionalized naphthalenes.

New Synthesis Of Poly(1,3,4-Oxadiazoles)

NASA Technical Reports Server (NTRS)

Connell, John W.; Hergenrother, Paul M.; Wolf, Peter

1992-01-01

Synthesis via aromatic nucleophilic displacement yields new high-molecular-weight polymers. Polymers exhibited good mechanical and thermal properties. Synthetic route provided high-molecular-weight POX of new chemical structure, potentially more economical. Availability of large variety of activated aromatic dihalides, facilitates variation of chemical structures. Exhibit properties making them useful as films. Also useful in coatings, adhesives, moldings, and composites.

40 CFR 442.2 - General definitions.

Code of Federal Regulations, 2010 CFR

2010-07-01

..., organic chemicals including: alcohols, aldehydes, formaldehydes, phenols, peroxides, organic salts, amines, amides, other nitrogen compounds, other aromatic compounds, aliphatic organic chemicals, glycols, glycerines, and organic polymers; refractory organic compounds including: ketones, nitriles, organo-metallic...

Photo-oxidation method using MoS2 nanocluster materials

DOEpatents

Wilcoxon, Jess P.

2001-01-01

A method of photo-oxidizing a hydrocarbon compound is provided by dispersing MoS.sub.2 nanoclusters in a solvent containing a hydrocarbon compound contaminant to form a stable solution mixture and irradiating the mixture to photo-oxide the hydrocarbon compound. Hydrocarbon compounds of interest include aromatic hydrocarbon and chlorinated hydrocarbons. MoS.sub.2 nanoclusters with an average diameter less than approximately 10 nanometers are shown to be effective in decomposing potentially toxic aromatic and chlorinated hydrocarbons, such as phenol, pentachlorophenol, chlorinated biphenols, and chloroform, into relatively non-toxic compounds. The irradiation can occur by exposing the MoS.sub.2 nanoclusters and hydrocarbon compound mixture with visible light. The MoS.sub.2 nanoclusters can be introduced to the toxic hydrocarbons as either a MoS.sub.2 solution or deposited on a support material.

Controlled release chamber for dispensing aromatic substances.

PubMed

Cilek, J E; Hallmon, C F

2008-12-01

A novel device for the containment and precise release of aromatic substances is described. The device consists of a threaded-tubular polyvinyl chloride chamber (and screw-top cap) with ports for introduction and release of gaseous compounds. This chamber is inexpensive, easy to assemble, and useful for evaluating the combined release of carbon dioxide and aromatic hygroscopic substances as mosquito attractants in field studies.

Poly(arylene ether)s That Resist Atomic Oxygen

NASA Technical Reports Server (NTRS)

Connell, John W.; Hergenrother, Paul; Smith, Joseph G., Jr.

1994-01-01

Novel poly(arylene ether)s containing phosphine oxide (PAEPO's) made via aromatic nucleophilic displacement reactions of activated aromatic dihalides (or, in some cases, activated aromatic dinitro compounds) with new bisphenol monomers containing phosphine oxide. Exhibited favorable combination of physical and mechanical properties and resistance to monatomic oxygen in oxygen plasma environment. Useful as adhesives, coatings, films, membranes, moldings, and composite matrices.

Mutagenicity of diesel exhaust particle extracts: influence of fuel composition in two diesel engines

DOE Office of Scientific and Technical Information (OSTI.GOV)

Clark, C.R.; Henderson, T.R.; Royer, R.E.

The influence of diesel fuel composition on mutagenicity of exhaust particle associated organic compounds has been investigated using nine fuels varying in aromatic content and distillation properties. The tests were conducted with Oldsmobile Delta-88 and Peugot 504 diesel cars operated according to the EPA Federal Test Procedure. The particulate exhaust from each test was collected on a filter, extracted in dichloromethane and the resulting extract evaluated for mutagenicity in Salmonella strain TA-100. Mutagenicity of extracts of particles collected from the Oldsmobile were highest in the higher aromatic content fuels (greater than 30%) but similar for intermediate (20%) and low (13%)more » aromatic content fuels. No influence of aromaticity on mutagenicity was observed in samples collected from the Peugeot under the same conditions. Thus, fuel aromatic content may enhance the production of mutagenic combustion products at higher concentrations, but may be dependent upon engine type. A good correlation was observed between mutagenicity of the particle extracts and the initial boiling point of the fuel (r . 0.89). Gas chromatography/mass spectrometric analysis of the aromatic fraction of the fuels showed that the fuel producing the most mutagenic combustion products was highest in phenanthrene type compounds.« less

The effect of aromatization on the isotopic compositions of hydrocarbons during early diagenesis

NASA Technical Reports Server (NTRS)

Freeman, K. H.; Boreham, C. J.; Summons, R. E.; Hayes, J. M.

1994-01-01

Polycyclic aromatic hydrocarbons with varying degrees of aromatization were isolated from the Eocene Messel Shale (Rheingraben, Germany). The high abundances of these compounds and their structural resemblances to cyclic triterpenoid lipids are consistent with derivation from microbial rather than thermal processes. Compounds structurally related to oleanane contain from five to nine double bonds; those within a series of aromatized hopanoids contain from three to nine. All are products of diagenetic reactions that remove hydrogen or methyl groups, and, in several cases, break carbon-carbon bonds to open rings. Aromatized products are on average depleted in 13C relative to possible precursors by l.2% (range: l.5% enrichment to 4% depletion, n = 9). The dependence of 13C content on the number of double bonds is not, however, statistically significant and it must be concluded that there is no strong evidence for isotopic fractionation accompanying diagenetic aromatization. Isotopic differences between series (structures related to ursane, des-A-ursane, des-A-lupane, des-A-arborane, and possibly, des-A-gammacerane are present) are much greater, indicating that 13C contents are controlled primarily by source effects. Fractionations due to chromatographic isotope effects during HPLC ranged from 0.1 to 2.8%.

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 commonly used gel permeation chromatography. The performance of the method (as expressed by mean recoveries and mean precision) was determined using Ottawa sand, a commercially available topsoil, and an environmental stream sediment, fortified at 1.5 and 15 micrograms per compound. Recoveries of PAH and semivolatile compounds in Ottawa sand samples fortified at 1.5 micrograms averaged 88 percent ? 9.4 percent relative standard deviation, and calculated initial method detection limits per compound averaged 14 micrograms per kilogram, assuming a 25-gram sample size. The recovery for 1,2,4-trichlorobenzene is less than 60 percent; thus, the concentration of this compound will always be reported as estimated with the E remark code. The analysis of 25 alkylated PAH homolog groups also can be determined with this method with extra data analysis and review, but because of the lack of authentic reference standard compounds, these results are considered to be semiquantitative. The PAH homolog groups are quantitated using the response factor of a parent PAH method compound, if available. Precision data for the alkylated PAH homologs detected in a marine sediment standard reference material (SRM 1944) also are presented to document and demonstrate method capability.

Risk-Based Evaluation of Total Petroleum Hydrocarbons in Vapor Intrusion Studies

PubMed Central

Brewer, Roger; Nagashima, Josh; Kelley, Michael; Heskett, Marvin; Rigby, Mark

2013-01-01

This paper presents a quantitative method for the risk-based evaluation of Total Petroleum Hydrocarbons (TPH) in vapor intrusion investigations. Vapors from petroleum fuels are characterized by a complex mixture of aliphatic and, to a lesser extent, aromatic compounds. These compounds can be measured and described in terms of TPH carbon ranges. Toxicity factors published by USEPA and other parties allow development of risk-based, air and soil vapor screening levels for each carbon range in the same manner as done for individual compounds such as benzene. The relative, carbon range makeup of petroleum vapors can be used to develop weighted, site-specific or generic screening levels for TPH. At some critical ratio of TPH to a targeted, individual compound, the overwhelming proportion of TPH will drive vapor intrusion risk over the individual compound. This is particularly true for vapors associated with diesel and other middle distillate fuels, but can also be the case for low-benzene gasolines or even for high-benzene gasolines if an adequately conservative, target risk is not applied to individually targeted chemicals. This necessitates a re-evaluation of the reliance on benzene and other individual compounds as a stand-alone tool to evaluate vapor intrusion risk associated with petroleum. PMID:23765191

Extraterrestrial Organic Compounds in Meteorites

NASA Technical Reports Server (NTRS)

Botta, Oliver; Bada, Jeffrey L.; Meyer, Michael (Technical Monitor)

2003-01-01

Many organic compounds or their precursors found in meteorites originated in the interstellar or circumstellar medium and were later incorporated into planetesimals during the formation of the solar system. There they either survived intact or underwent further processing to synthesize secondary products on the meteorite parent body. The most distinct feature of CI and CM carbonaceous chondrites, two types of stony meteorites, is their high carbon content (up to 3% of weight), either in the form of carbonates or of organic compounds. The bulk of the organic carbon consists of an insoluble macromolecular material with a complex structure. Also present is a soluble organic fraction, which has been analyzed by several separation and analytical procedures. Low detection limits can be achieved by derivatization of the organic molecules with reagents that allow for analysis by gas chromatography/mass spectroscopy and high performance liquid chromatography. The CM meteorite Murchison has been found to contain more than 70 extraterrestrial amino acids and several other classes of compounds including carboxylic acids, hydroxy carboxylic acids, sulphonic and phosphonic acids, aliphatic, aromatic and polar hydrocarbons, fullerenes, heterocycles as well as carbonyl compounds, alcohols, amines and amides. The organic matter was found to be enriched in deuterium, and distinct organic compounds show isotopic enrichments of carbon and nitrogen relative to terrestrial matter.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lee, B.D.; Apel, W.A.; Walton, M.R.

Conceptually, biofilters are vapor phase bioreactors that rely on microorganisms in the bed medium to oxidize contaminants in off-gases flowing through the bed to less hazardous compounds. In the most studied and utilized systems reduced compounds such as fuel hydrocarbons are enzymatically oxidized to compounds such as carbon dioxide and water. In these types of reactions the microorganisms in the bed oxidize the contaminant and transfer the electrons to oxygen which is the terminal electron acceptor in the process. In essence the contaminant is the carbon and energy source for the microorganisms in the bed medium and through this catabolicmore » process oxygen is reduced to water. An example of this oxidation process can be seen during the degradation of benzene and similar aromatic compounds. Aromatics are initially attacked by a dioxygenase enzyme which oxidizes the compounds to a labile dihydrodiole which is spontaneously converted to a catechol. The dihydroxylated aromatic rings is then opened by oxidative {open_quotes}ortho{close_quotes} or {open_quotes}meta{close_quotes} cleavage yielding cis, cis-muconic acid or 2-hydroxy-cis, cis-muconic semialdehyde, respectively. These organic compounds are further oxidized to carbon dioxide or are assimilated for cellular material. This paper describes the conversion of carbon tetrachloride using methanol as the primary carbon and energy source.« less

Pseudomonas putida as a platform for the synthesis of aromatic compounds.

PubMed

Molina-Santiago, Carlos; Cordero, Baldo F; Daddaoua, Abdelali; Udaondo, Zulema; Manzano, Javier; Valdivia, Miguel; Segura, Ana; Ramos, Juan-Luis; Duque, Estrella

2016-09-01

Aromatic compounds such as l-phenylalanine, 2-phenylethanol and trans-cinnamate are aromatic compounds of industrial interest. Current trends support replacement of chemical synthesis of these compounds by 'green' alternatives produced in microbial cell factories. The solvent-tolerant Pseudomonas putida DOT-T1E strain was genetically modified to produce up to 1 g l-1 of l-phenylalanine. In order to engineer this strain, we carried out the following stepwise process: (1) we selected random mutants that are resistant to toxic phenylalanine analogues; (2) we then deleted up to five genes belonging to phenylalanine metabolism pathways, which greatly diminished the internal metabolism of phenylalanine; and (3) in these mutants, we overexpressed the pheAfbr gene, which encodes a recombinant variant of PheA that is insensitive to feedback inhibition by phenylalanine. Furthermore, by introducing new genes, we were able to further extend the diversity of compounds produced. Introduction of histidinol phosphate transferase (PP_0967), phenylpyruvate decarboxylase (kdc) and an alcohol dehydrogenase (adh) enabled the strain to produce up to 180 mg l-1 2-phenylethanol. When phenylalanine ammonia lyase (pal) was introduced, the resulting strain produced up to 200 mg l-1 of trans-cinnamate. These results demonstrate that P. putida can serve as a promising microbial cell factory for the production of l-phenylalanine and related compounds.

The chemistry of subcritical water reactions of a hardwood derived lignin and lignin model compounds with nitrogen, hydrogen, carbon monoxide and carbon dioxide

NASA Astrophysics Data System (ADS)

Hill Bembenic, Meredith A.

Biofuels, like cellulosic ethanol, may only be cost effective if the lignin byproduct is upgraded to value-added products. However, lignin's inherent aromatic structure and interunit crosslinkages hinder effective conversion. High temperature H2O is considered for lignin conversion, because H2O exhibits unusual properties at higher temperatures (particularly at its supercritical point of 374°C and 3205 psi) including a decreased ion product and a decreased static dielectric constant (similar to those of polar organic solvents at room temperature) such that there is a high solubility for organic compounds, like lignin. Much of the research concerning lignin and supercritical H2O has focused on further decomposition to gases (e.g., H2, CH4, and CO2) where nearly no char formation is expected in the presence of a catalyst. However, the conditions required for supercritical H2O are difficult to maintain, catalysts can be expensive, and gases are not favorable to the current liquid fuel infrastructure. Reactions using Organosolv lignin, subcritical H2O (365°C) and various industrial gases (N2, H2, CO, and CO2 at an initial pressure of 500 psi) for 30 min. were examined to determine both lignin's potential to generate value-added products (e.g., monomer compounds and methanol) and the role (if any) of the H2O and the gases during the reactions. The behavior of H2O at reaction temperature and pressure is expected to be similar to the behavior of supercritical H 2O without the need to maintain supercritical conditions. Different characterization techniques were used for the products collected including primarily GC/FID-TCD of the evolved gases, GC/MS analysis of the organic liquids, solid phase microextraction analysis of the water, and solid state 13C-NMR analysis of the residues. The reactor pressure at temperature was shown to influence the reactivity of the H2O and lignin, and the highest conversions (≈54--62%) were obtained when adding a gas. However, the collected solids from the CO reactions appeared to be the most reacted (i.e., the most changed from the unreacted lignin) according to solid state 13C-NMR analysis, and the widest variety of products (methoxy-substituted phenolic compounds) were obtained when using CO according to GC/MS analysis. Therefore, reactions with CO were completed that varied the initial reaction pressure (300, 500 and 800 psi) in order to elucidate the effects of CO pressure. Similar conversion (≈54--58%) and DCM-soluble liquid product yields (≈53--62%) were obtained for the different pressure reactions, but the reactions with an initial pressure of 500 psi had the greatest change in aromaticity from the unreacted lignin. Additional reactions between Organosolv lignin and H2O with CO (initial pressure of 500 psi) were conducted where the reaction time was varied (15, 30 and 60 min.) to determine the effect of reaction time. Longer reaction time (60 min.) appeared to inhibit conversion to low molecular weight compounds (i.e., conversion and DCM-soluble yields were lower at ≈53% and ≈28%, respectively). Solid state 13C-NMR of collected residues also showed that there are losses in carbons representative of both guaiacyl and syringyl components as reaction time increases, which may indicate that methoxy groups are being cleaved or the products are reacting with each other (i.e., repolymerization) to form high molecular weight compounds as reaction time is increased. The role of H2O and the gases during the baseline reactions and the expanded CO reactions is not intuitive based on the results, so reactions with lignin model compounds (i.e., aromatic aldehydes represented by vanillin and syringaldehyde, aromatic ketones represented by acetovanillone and acetosyringone, and aromatic ethers represented by dibenzyl ether and 2-phenethyl phenyl ether) were completed to study this. From these results, the suggested reaction pathway of Organosolv lignin reactions in subcritical H2O with and without added pressure is: 1) cleavage of ethers (via hydrolysis) to form smaller methoxy-substituted phenolic monomers with aldehyde- or ketone-substituents representative of lignin monomers; 2) cleavage of the methoxy-, aldehyde- and/or ketone-substituents to form primarily methoxy-substituted phenolic monomers; 3) rearrangement of these phenolic monomers due to the enhanced pressure at reaction temperature; 4) formation of oligomers due to interaction amongst the methoxy-substituted phenolic monomers, which is also due to the enhanced pressure at reaction temperature; and 5) repolymerization of the monomers and oligomers to form high molecular weight compounds (i.e., longer reactions times or different pressures seemed to enhance these reactions). Under these conditions, depolymerization seems to be the dominant reaction pathway versus repolymerization. Reactions with lignin and H2O at 365°C have not been previously reported nor has the reaction chemistry for lignin depolymerization at these conditions been established. The results with lignin (or lignin model compounds), subcritical H2O and CO also show that the desired product slate can be modified with different pressure and time conditions. In particular, increasing reaction time (from 15 to 60 min.) caused lignin conversion to decrease, and the products appeared to be reacting with each other. However, the longer reaction time also showed that more methanol is generated (along with more solids).

Forensic fingerprinting of oil-spill hydrocarbons in a methanogenic environment-Mandan, ND and Bemidji, MN

USGS Publications Warehouse

Hostettler, F.D.; Wang, Y.; Huang, Y.; Cao, W.; Bekins, B.A.; Rostad, C.E.; Kulpa, C.F.; Laursen, Andrew E.

2007-01-01

In recent decades forensic fingerprinting of oil-spill hydrocarbons has emerged as an important tool for correlating oils and for evaluating their source and character. Two long-term hydrocarbon spills, an off-road diesel spill (Mandan, ND) and a crude oil spill (Bemidji, MN) experiencing methanogenic biodegradation were previously shown to be undergoing an unexpected progression of homologous n-alkane and n-alkylated cyclohexane loss. Both exhibited degradative losses proceeding from the high-molecular-weight end of the distributions, along with transitory concentration increases of lower-molecular-weight homologs. Particularly in the case of the diesel fuel spill, these methanogenic degradative patterns can result in series distributions that mimic lower cut refinery fuels or admixture with lower cut fuels. Forensic fingerprinting in this long-term spill must therefore rely on more recalcitrant series, such as polycyclic aromatic hydrocarbon or drimane sesquiterpane profiles, to prove if the spilled oil is single-sourced or whether there is verifiable admixture with other extraneous refinery fuels. Degradation processes impacting n-alkanes and n-alkylated ring compounds, which make these compounds unsuitable for fingerprinting, nevertheless are of interest in understanding methanogenic biodegradation. Copyright ?? Taylor & Francis Group, LLC.

The Impact of Single Amino Acids on Growth and Volatile Aroma Production by Saccharomyces cerevisiae Strains

PubMed Central

Fairbairn, Samantha; McKinnon, Alexander; Musarurwa, Hannibal T.; Ferreira, António C.; Bauer, Florian F.

2017-01-01

Nitrogen availability and utilization by Saccharomyces cerevisiae significantly influence fermentation kinetics and the production of volatile compounds important for wine aroma. Amino acids are the most important nitrogen source and have been classified based on how well they support growth. This study evaluated the effect of single amino acids on growth kinetics and major volatile production of two phenotypically different commercial wine yeast strains in synthetic grape must. Four growth parameters, lag phase, maximum growth rate, total biomass formation and time to complete fermentation were evaluated. In contrast with previous findings, in fermentative conditions, phenylalanine and valine supported growth well and asparagine supported it poorly. The four parameters showed good correlations for most amino acid treatments, with some notable exceptions. Single amino acid treatments resulted in the predictable production of aromatic compounds, with a linear correlation between amino acid concentration and the concentration of aromatic compounds that are directly derived from these amino acids. With the increased complexity of nitrogen sources, linear correlations were lost and aroma production became unpredictable. However, even in complex medium minor changes in amino acid concentration continued to directly impact the formation of aromatic compounds, suggesting that the relative concentration of individual amino acids remains a predictor of aromatic outputs, independently of the complexity of metabolic interactions between carbon and nitrogen metabolism and between amino acid degradation and utilization pathways. PMID:29312237

The Impact of Single Amino Acids on Growth and Volatile Aroma Production by Saccharomyces cerevisiae Strains.

PubMed

Fairbairn, Samantha; McKinnon, Alexander; Musarurwa, Hannibal T; Ferreira, António C; Bauer, Florian F

2017-01-01

Nitrogen availability and utilization by Saccharomyces cerevisiae significantly influence fermentation kinetics and the production of volatile compounds important for wine aroma. Amino acids are the most important nitrogen source and have been classified based on how well they support growth. This study evaluated the effect of single amino acids on growth kinetics and major volatile production of two phenotypically different commercial wine yeast strains in synthetic grape must. Four growth parameters, lag phase, maximum growth rate, total biomass formation and time to complete fermentation were evaluated. In contrast with previous findings, in fermentative conditions, phenylalanine and valine supported growth well and asparagine supported it poorly. The four parameters showed good correlations for most amino acid treatments, with some notable exceptions. Single amino acid treatments resulted in the predictable production of aromatic compounds, with a linear correlation between amino acid concentration and the concentration of aromatic compounds that are directly derived from these amino acids. With the increased complexity of nitrogen sources, linear correlations were lost and aroma production became unpredictable. However, even in complex medium minor changes in amino acid concentration continued to directly impact the formation of aromatic compounds, suggesting that the relative concentration of individual amino acids remains a predictor of aromatic outputs, independently of the complexity of metabolic interactions between carbon and nitrogen metabolism and between amino acid degradation and utilization pathways.

Comprehensive GC²/MS for the monitoring of aromatic tar oil constituents during biodegradation in a historically contaminated soil.

PubMed

Vasilieva, Viktoriya; Scherr, Kerstin E; Edelmann, Eva; Hasinger, Marion; Loibner, Andreas P

2012-02-20

The constituents of tar oil comprise a wide range of physico-chemically heterogeneous pollutants of environmental concern. Besides the sixteen polycyclic aromatic hydrocarbons defined as priority pollutants by the US-EPA (EPA-PAHs), a wide range of substituted (NSO-PAC) and alkylated (alkyl-PAC) aromatic tar oil compounds are gaining increased attention for their toxic, carcinogenic, mutagenic and/or teratogenic properties. Investigations on tar oil biodegradation in soil are in part hampered by the absence of an efficient analytical tool for the simultaneous analysis of this wide range of compounds with dissimilar analytical properties. Therefore, the present study sets out to explore the applicability of comprehensive two-dimensional gas chromatography (GC²/MS) for the simultaneous measurement of compounds with differing polarity or that are co-eluting in one-dimensional systems. Aerobic tar oil biodegradation in a historically contaminated soil was analyzed over 56 days in lab-scale bioslurry tests. Forty-three aromatic compounds were identified with GC²/MS in one single analysis. The number of alkyl chains on a molecule was found to prime over alkyl chain length in hampering compound biodegradation. In most cases, substitution of carbon with nitrogen and oxygen was related to increased compound degradation in comparison to unalkylated and sulphur- or unsubstituted PAH with a similar ring number.The obtained results indicate that GC²/MS can be employed for the rapid assessment of a large variety of structurally heterogeneous environmental contaminants. Its application can contribute to facilitate site assessment, development and control of microbial cleanup technologies for tar oil contaminated sites. Copyright © 2011 Elsevier B.V. All rights reserved.

Classification of the fragrant styles and evaluation of the aromatic quality of flue-cured tobacco leaves by machine-learning methods.

PubMed

Gu, Li; Xue, Lichun; Song, Qi; Wang, Fengji; He, Huaqin; Zhang, Zhongyi

2016-12-01

During commercial transactions, the quality of flue-cured tobacco leaves must be characterized efficiently, and the evaluation system should be easily transferable across different traders. However, there are over 3000 chemical compounds in flue-cured tobacco leaves; thus, it is impossible to evaluate the quality of flue-cured tobacco leaves using all the chemical compounds. In this paper, we used Support Vector Machine (SVM) algorithm together with 22 chemical compounds selected by ReliefF-Particle Swarm Optimization (R-PSO) to classify the fragrant style of flue-cured tobacco leaves, where the Accuracy (ACC) and Matthews Correlation Coefficient (MCC) were 90.95% and 0.80, respectively. SVM algorithm combined with 19 chemical compounds selected by R-PSO achieved the best assessment performance of the aromatic quality of tobacco leaves, where the PCC and MSE were 0.594 and 0.263, respectively. Finally, we constructed two online tools to classify the fragrant style and evaluate the aromatic quality of flue-cured tobacco leaf samples. These tools can be accessed at http://bioinformatics.fafu.edu.cn/tobacco .

Sodium Perborate Oxidation of an Aromatic Amine

ERIC Educational Resources Information Center

Juestis, Laurence

1977-01-01

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

Automated analysis of oxidative metabolites

NASA Technical Reports Server (NTRS)

Furner, R. L. (Inventor)

1974-01-01

An automated system for the study of drug metabolism is described. The system monitors the oxidative metabolites of aromatic amines and of compounds which produce formaldehyde on oxidative dealkylation. It includes color developing compositions suitable for detecting hyroxylated aromatic amines and formaldehyde.

PTR-MS Characterization of VOCs Associated with Commercial Aromatic Bakery Yeasts of Wine and Beer Origin.

PubMed

Capozzi, Vittorio; Makhoul, Salim; Aprea, Eugenio; Romano, Andrea; Cappellin, Luca; Sanchez Jimena, Ana; Spano, Giuseppe; Gasperi, Flavia; Scampicchio, Matteo; Biasioli, Franco

2016-04-12

In light of the increasing attention towards "green" solutions to improve food quality, the use of aromatic-enhancing microorganisms offers the advantage to be a natural and sustainable solution that did not negatively influence the list of ingredients. In this study, we characterize, for the first time, volatile organic compounds (VOCs) associated with aromatic bakery yeasts. Three commercial bakery starter cultures, respectively formulated with three Saccharomyces cerevisiae strains, isolated from white wine, red wine, and beer, were monitored by a proton-transfer-reaction time-of-flight mass spectrometer (PTR-ToF-MS), a direct injection analytical technique for detecting volatile organic compounds with high sensitivity (VOCs). Two ethanol-related peaks (m/z 65.059 and 75.080) described qualitative differences in fermentative performances. The release of compounds associated to the peaks at m/z 89.059, m/z 103.075, and m/z 117.093, tentatively identified as acetoin and esters, are coherent with claimed flavor properties of the investigated strains. We propose these mass peaks and their related fragments as biomarkers to optimize the aromatic performances of commercial preparations and for the rapid massive screening of yeast collections.

Ecology, physiology, and phylogeny of deep subsurface Sphingomonas sp.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Fredrickson, Jim K.; Balkwill, David L.; Romine, Margaret F.

Several new species of the genus Sphingomonas including S. aromaticivorans, S. stygia, and S. subterranea that have the capacity for degrading a broad range of aromatic compounds including toluene, naphthalene, xylenes, p-cresol, fluorene, biphenyl, and dibenzothiophene, were isolated from deeply-buried (>200 m) sediments of the US Atlantic coastal plain (ACP). In S. aromaticivorans F199, many of the genes involved in the catabolism of these aromatic compounds are encoded on a 184-kb conjugative plasmid; some of the genes involved in aromatic catabolism are plasmid-encoded in the other strains as well. Members of the genus Sphingomonas were common among aerobic heterotrophic bacteriamore » cultured from ACP sediments and have been detected in deep subsurface environments elsewhere. The major source of organic carbon for heterotrophic metabolism in ACP deep aquifers is lignite that originated from plant material buried with the sediments. We speculate that the ability of the subsurface Sphingomonas strains to degrade a wide array of aromatic compounds represents an adaptation for utilization of sedimentary lignite. These and related subsurface Sphingomonas spp may play an important role in the transformation of sedimentary organic carbon in the aerobic and microaerobic regions of the deep aquifers of the ACP.« less

Remediation of aged diesel contaminated soil by alkaline activated persulfate.

PubMed

Lominchar, M A; Santos, A; de Miguel, E; Romero, A

2018-05-01

The present work studies the efficiency of alkaline activated persulfate (PS) to remediate an aged diesel fuel contaminated soil from a train maintenance facility. The Total Petroleum Hydrocarbon (TPH) concentration in soil was approximately 5000mgkg -1 with a ratio of aliphatic:aromatic compounds of 70:30. Aromatic compounds were mainly naphtalenes and phenanthrenes. The experiments were performed in batch mode where different initial concentrations of persulfate (105mM, 210mM and 420mM) and activator:persulfate ratios (2 and 4) were evaluated, with NaOH used as activator. Runs were carried out during 56days. Complete TPH conversion was obtained with the highest concentration of PS and activator, whereas in the other runs the elimination of fuel ranged between 60 and 77%. Besides, the abatement of napthalenes and phenantrenes was faster than aliphatic reduction (i. e. after 4days of treatment, the conversions of the aromatic compounds were around 0.8 meanwhile the aliphatic abatements were 0.55) and no aromatic oxidation intermediates from naphtalenes or phenantrenes were detected. These results show that this technology is effective for the remediation of aged diesel in soil with alkaline pH. Copyright © 2017 Elsevier B.V. All rights reserved.

Biologically important compounds in synfuels processes

DOE Office of Scientific and Technical Information (OSTI.GOV)

Clark, B R; Ho, C; Griest, W H

1980-01-01

Crude products, by-products and wastes from synfuel processes contain a broad spectrum of chemical compounds - many of which are active in biological systems. Discerning which compound classes are most important is necessary in order to establish effective control over release or exposure. Polycyclic aromatic hydrocarbons (PAH), multialkylated PAH, primary aromatic amines and N-heterocyclic PAH are significant contributors to the overall mutagenic activities of a large number of materials examined. Ames test data show that the basic, primary aromatic amine fraction is the most active. PAHs, multialkylated PAHs and N-heterocyclic PAHs are all components of the neutral fraction. In nearlymore » all cases, the neutral fractions contribute the largest portion of the mutagenic activity, while the basic primary aromatic amine fractions have the highest specific activity. Neutral fractions are usually the largest (wt %) whereas the total basic fractions are small by comparison; thus, the overall greater contribution of the neutral fraction to the mutagenic activity of most samples. Biologically active constituents are isolated in preparative scale amounts from complex mixtures utilizing combinations of liquid-liquid extraction and various liquid chromatographic column-eluant combinations. Fractions are characterized using a combination of spectroscopic techniques and gas chromatography/mass spectrometry.« less

Ecology, physiology, and phylogeny of deep subsurface Sphingomonas sp.

PubMed

Fredrickson, J K; Balkwill, D L; Romine, M F; Shi, T

1999-10-01

Several new species of the genus Sphingomonas including S. aromaticivorans, S. stygia, and S. subterranea that have the capacity for degrading a broad range of aromatic compounds including toluene, naphthalene, xylenes, p-cresol, fluorene, biphenyl, and dibenzothiophene, were isolated from deeply-buried (>200 m) sediments of the US Atlantic coastal plain (ACP). In S. aromaticivorans F199, many of the genes involved in the catabolism of these aromatic compounds are encoded on a 184-kb conjugative plasmid; some of the genes involved in aromatic catabolism are plasmid-encoded in the other strains as well. Members of the genus Sphingomonas were common among aerobic heterotrophic bacteria cultured from ACP sediments and have been detected in deep subsurface environments elsewhere. The major source of organic carbon for heterotrophic metabolism in ACP deep aquifers is lignite that originated from plant material buried with the sediments. We speculate that the ability of the subsurface Sphingomonas strains to degrade a wide array of aromatic compounds represents an adaptation for utilization of sedimentary lignite. These and related subsurface Sphingomonas spp may play an important role in the transformation of sedimentary organic carbon in the aerobic and microaerobic regions of the deep aquifers of the ACP.

Engineering Escherichia coli to overproduce aromatic amino acids and derived compounds.

PubMed

Rodriguez, Alberto; Martínez, Juan A; Flores, Noemí; Escalante, Adelfo; Gosset, Guillermo; Bolivar, Francisco

2014-09-09

The production of aromatic amino acids using fermentation processes with recombinant microorganisms can be an advantageous approach to reach their global demands. In addition, a large array of compounds with alimentary and pharmaceutical applications can potentially be synthesized from intermediates of this metabolic pathway. However, contrary to other amino acids and primary metabolites, the artificial channelling of building blocks from central metabolism towards the aromatic amino acid pathway is complicated to achieve in an efficient manner. The length and complex regulation of this pathway have progressively called for the employment of more integral approaches, promoting the merge of complementary tools and techniques in order to surpass metabolic and regulatory bottlenecks. As a result, relevant insights on the subject have been obtained during the last years, especially with genetically modified strains of Escherichia coli. By combining metabolic engineering strategies with developments in synthetic biology, systems biology and bioprocess engineering, notable advances were achieved regarding the generation, characterization and optimization of E. coli strains for the overproduction of aromatic amino acids, some of their precursors and related compounds. In this paper we review and compare recent successful reports dealing with the modification of metabolic traits to attain these objectives.

Herbal medicine, radical scavenger and metal detoxification: bioinorganic, complexity and nano science perspectives

NASA Astrophysics Data System (ADS)

Sumitro, Sutiman B.; Alit, Sukmaningsih

2018-03-01

Developing Complexity Science and Nano Biological perspective giving the ideas of interfacing between modern physical and biological sciences for more comprehensive understanding of life. The study of bioinorganic is a trans-disciplinary, and will initiate the way to more comprehensive and better understanding life. We can talk about energy generation, motive forces and energy transfer at the level of macromolecules. We can then develop understanding biological behavior on nano size biological materials and its higher order using modern physics as well as thermodynamic law. This is a necessity to ovoid partial understanding of life that are not match with holism. In animal tissues, the accumulation or overwhelmed production of free radicals can damage cells and are believed to accelerate the progression of cancer, cardiovascular disease, and age-related diseases. Thus a guarded balance of radical species is imperative. Edward Kosower [1] proposed an idea of biradical in an aromatic organic compounds. Each of which having unpaired electrons. The magnetic force of this compound used for making agregation based on their magnetic characters. Bioinorganic low molecular weight complex compounds composing herbal medicine can bind toxic metals. This low molecular weight complex molecules then easily excerted the metals from the body, removing them from their either intracellular or extracellular existences. This bioinorganic chelation potential is now inspiring a new therapeutic strategies.

Distribution of polycyclic aromatic hydrocarbons in the food web of a high mountain lake, Pyrenees, Catalonia, Spain.

PubMed

Vives, Ingrid; Grimalt, Joan O; Ventura, Marc; Catalan, Jordi

2005-06-01

We investigated the contents of polycyclic aromatic hydrocarbons (PAHs) in the food web organisms included in the diet of brown trout from a remote mountain lake. The preferential habitat and trophic level of the component species have been assessed from the signature of stable isotopes (delta13C and delta15N). Subsequently, the patterns of accumulation and transformation of these hydrocarbons in the food chain have been elucidated. Most of the food web organisms exhibit PAH distributions largely dominated by phenanthrene, which agrees with its predominance in atmospheric deposition, water, and suspended particles. Total PAH levels are higher in the organisms from the littoral habitat than from the deep sediments or the pelagic water column. However, organisms from deep sediments exhibit higher proportions of higher molecular weight PAH than those in other lake areas. Distinct organisms exhibit specific features in their relative PAH composition that point to different capacities for uptake and metabolic degradation. Brown trout show an elevated capacity for metabolic degradation because they have lower PAH concentrations than food and they are enriched strongly in lower molecular weight compounds. The PAH levels in trout highly depend on organisms living in the littoral areas. Fish exposure to PAH, therefore, may vary from lake to lake according to the relative contribution of littoral organisms to their diet.

Biotransformation and Detoxification of Xylidine Orange Dye Using Immobilized Cells of Marine-Derived Lysinibacillus sphaericus D3

PubMed Central

Devi, Prabha; Wahidullah, Solimabi; Sheikh, Farhan; Pereira, Rochelle; Narkhede, Niteen; Amonkar, Divya; Tilvi, Supriya; Meena, Ram Murthy

2017-01-01

Lysinibacillus sphaericus D3 cell-immobilized beads in natural gel sodium alginate decolorized the xylidine orange dye 1-(dimethylphenylazo)-2-naphthol-6-sulfonic acid sodium salt in the laboratory. Optimal conditions were selected for decolorization and the products formed were evaluated for toxicity by disc diffusion assay against common marine bacteria which revealed the non-toxic nature of the dye-degraded products. Decolorization of the brightly colored dye to colorless products was measured on an Ultra Violet-Vis spectrophotometer and its biodegradation products monitored on Thin Layer Chromatographic plate and High Performance Liquid Chromatography (HPLC). Finally, the metabolites formed in the decolorized medium were characterized by mass spectrometry. This analysis confirms the conversion of the parent molecule into lower molecular weight aromatic phenols and sulfonic acids as the final products of biotransformation. Based on the results, the probable degradation products of xylidine orange were naphthol, naphthylamine-6-sulfonic acid, 2-6-dihydroxynaphthalene, and bis-dinaphthylether. Thus, it may be concluded that the degradation pathway of the dye involved (a) reduction of its azo group by azoreductase enzyme (b) dimerization of the hydrazo compound followed by (c) degradation of monohydrazo as well as dimeric metabolites into low molecular weight aromatics. Finally, it may be worth exploring the possibility of commercially utilizing L. sphaericus D3 for industrial applications for treating large-scale dye waste water. PMID:28208715

Household air pollution and personal exposure to nitrated and oxygenated polycyclic aromatics (PAHs) in rural households: Influence of household cooking energies.

PubMed

Chen, Y; Du, W; Shen, G; Zhuo, S; Zhu, X; Shen, H; Huang, Y; Su, S; Lin, N; Pei, L; Zheng, X; Wu, J; Duan, Y; Wang, X; Liu, W; Wong, M; Tao, S

2017-01-01

Residential solid fuels are widely consumed in rural China, contributing to severe household air pollution for many products of incomplete combustion, such as polycyclic aromatic hydrocarbons (PAHs) and their polar derivatives. In this study, concentrations of nitrated and oxygenated PAH derivatives (nPAHs and oPAHs) for household and personal air were measured and analyzed for influencing factors like smoking and cooking energy type. Concentrations of nPAHs and oPAHs in kitchens were higher than those in living rooms and in outdoor air. Exposure levels measured by personal samplers were lower than levels in indoor air, but higher than outdoor air levels. With increasing molecular weight, individual compounds tended to be more commonly partitioned to particulate matter (PM); moreover, higher molecular weight nPAHs and oPAHs were preferentially found in finer particles, suggesting a potential for increased health risks. Smoking behavior raised the concentrations of nPAHs and oPAHs in personal air significantly. People who cooked food also had higher personal exposures. Cooking and smoking have a significant interaction effect on personal exposure. Concentrations in kitchens and personal exposure to nPAHs and oPAHs for households using wood and peat were significantly higher than for those using electricity and liquid petroleum gas (LPG). © 2016 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

Identification of genotoxic compounds in crude oil using fractionation according to distillation, polarity and Kow.

PubMed

Park, Shin Yeong; Lee, Hyo Jin; Khim, Jong Seong; Kim, Gi Beum

2017-01-30

We examined the degree of DNA damage caused by fractions of crude oil in accordance with the boiling points, polarity and log K ow . Relatively high DNA damage was observed in the aromatic fraction (290-330°C) and resin and polar fraction (350-400°C). The resin and polar fraction showed relatively high genotoxicity compared with the aliphatic and aromatic fraction at the 1-4 log K ow range. At the 6-7 log K ow range, the aromatic fraction showed relatively high DNA damage compared with the aliphatic and resin and polar fraction. In particular, every detailed fraction in accordance with the log K ow values (aliphatic and aromatic (310-320°C) and resins and polar fractions (370-380°C)) showed one or less than one DNA damage. However, the fractions before separation in accordance with log K ow values (aliphatic and aromatic (310-320°C) and resin and polar (370-380°C) fractions) showed high DNA damage. Thus, we confirm the synergistic action between the detailed compounds. Copyright © 2016 Elsevier Ltd. All rights reserved.

Aromatic volatile organic compounds and their role in ground-level ozone formation in Russia

NASA Astrophysics Data System (ADS)

Berezina, E. V.; Moiseenko, K. B.; Skorokhod, A. I.; Elansky, N. F.; Belikov, I. B.

2017-05-01

This paper reports proton mass spectrometry data on aromatic volatile organic compounds (VOCs) (benzene, toluene, phenol, styrene, xylene, and propylbenzene) obtained in different Russian regions along the Trans-Siberian Railway from Moscow to Vladivostok, based on expedition data retrieved using the TRO-ICA-12 mobile laboratory in the summer of 2008. The contribution of aromatic VOCs to ozone formation in the cities and regions along the measurement route has been estimated quantitatively. The greatest contribution of aromatic VOCs to ozone formation is characteristic of large cities along the Trans-Siberian Railway (up to 7.5 ppbv O3) specified by the highest concentrations of aromatic VOCs (1-1.7 ppbv) and nitrogen oxides (>20 ppbv). The results obtained are indicative of a considerable contribution (30-50%) of anthropogenic emissions of VOCs to photochemical ozone generation in the large cities along the Trans-Siberian Railway in hot and dry weather against the background of a powerful natural factor such as isoprene emissions controlling the regional balance of ground-level ozone in warm seasons.

Process for detoxifying coal tars

DOEpatents

Longwell, John P.; Peters, William A.

1983-01-01

A process for treating liquid hydrocarbons to remove toxic, mutagenic and/or carcinogenic aromatic hydrocarbons comprises feeding the hydrocarbons into a reactor where vapors are thermally treated in contact with a catalyst consisting essentially of calcium oxide or a calcium oxide containing mineral. Thermally treating liquid hydrocarbons in contact with calcium oxide preferentially increases the cracking of aromatics thus producing a product having a reduced amount of aromatic compounds.

Polyphenylquinoxalines via aromatic nucleophilic displacement

NASA Technical Reports Server (NTRS)

Hergenrother, Paul M. (Inventor); Connell, John W. (Inventor)

1990-01-01

Polyphenylquinoxalines are prepared by the nucleophilic displacement reaction of di(hydroxyphenyl)quinoxaline monomers with activated aromatic dihalides or dinitro compounds. The reactions are carried out in polar aprotic solvents using alkali metal bases at elevated temperatures under nitrogen. The di(hydroxyphenyl)quinoxaline monomers are prepared either by reacting stoichiometric quantities of aromatic bis(o-diamines) with a hydroxybenzil or by reacting o-phenylenediamine with a dihydroxybenzil or bis(hydroxyphenylglyoxylyl)benzene.

Polyphenylquinoxalines via aromatic nucleophilic displacement

NASA Technical Reports Server (NTRS)

Hergenrother, Paul M. (Inventor); Connell, John W. (Inventor)

1991-01-01

Polyphenylquinoxalines are prepared by the nucleophilic displacement reaction of di(hydroxyphenyl)quinoxaline monomers with activated aromatic dihalides or dinitro compounds. The reactions are carried out in polar aprotic solvents during alkali metal bases at elevated temperatures under nitrogen. The di(hydroxyphenyl)quinoxaline monomers are prepared either by reacting stoichiometric quantities of aromatic bis(o-diamines) with a hydroxybenzil or by reacting o-phenylenediamine with a dihydroxybenzil or bis(hydroxyphenylglyoxylyl)benzene.

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

Comparing molecular composition of dissolved organic matter in soil and stream water: Influence of land use and chemical characteristics.

PubMed

Seifert, Anne-Gret; Roth, Vanessa-Nina; Dittmar, Thorsten; Gleixner, Gerd; Breuer, Lutz; Houska, Tobias; Marxsen, Jürgen

2016-11-15

Electrospray ionization Fourier transform ion cyclotron resonance mass spectrometry (ESI-FT-ICR-MS) was used to examine the molecular composition of dissolved organic matter (DOM) from soils under different land use regimes and how the DOM composition in the catchment is reflected in adjacent streams. The study was carried out in a small area of the Schwingbach catchment, an anthropogenic-influenced landscape in central Germany. We investigated 30 different soil water samples from 4 sites and different depths (managed meadow (0-5cm, 40-50cm), deciduous forest (0-5cm), mixed-coniferous forest (0-5cm) and agricultural land (0-5cm, 40-50cm)) and 8 stream samples. 6194 molecular formulae and their magnitude-weighted parameters ((O/C)w, (H/C)w, (N/C)w, (AI-mod)w, (DBE/C)w, (DBE/O)w, (DBE-O)w, (C#)w, (MW)w) were used to describe the molecular composition of the samples. The samples can be roughly divided in three groups. Group 1 contains samples from managed meadow 40-50cm and stream water, which are characterized by high saturation compared to samples from group 2 including agricultural samples and samples from the surface meadow (0-5cm), which held more nitrogen containing and aromatic compounds. Samples from both forested sites (group 3) are characterized by higher molecular weight and O/C ratio. Environmental parameters vary between sites and among these parameters pH and nitrate significantly affect chemical composition of DOM. Results indicate that most DOM in streams is of terrestrial origin. However, 120 molecular formulae were detected only in streams and not in any of the soil samples. These compounds share molecular formulae with peptides, unsaturated aliphatics and saturated FA-CHO/FA-CHOX. Compounds only found in soil samples are much more aromatic, have more double bonds and a much lower H/C ratio but higher oxygen content, which indicates the availability of fresh plant material and less microbial processed material compared to stream samples. Copyright © 2016 Elsevier B.V. All rights reserved.

Enzymes involved in a novel anaerobic cyclohexane carboxylic acid degradation pathway.

PubMed

Kung, Johannes W; Meier, Anne-Katrin; Mergelsberg, Mario; Boll, Matthias

2014-10-01

The anaerobic degradation of cyclohexane carboxylic acid (CHC) has so far been studied only in Rhodopseudomonas palustris, in which CHC is activated to cyclohexanoyl coenzyme A (cyclohexanoyl-CoA [CHCoA]) and then dehydrogenated to cyclohex-1-ene-1-carboxyl-CoA (CHeneCoA). This intermediate is further degraded by reactions of the R. palustris-specific benzoyl-CoA degradation pathway of aromatic compounds. However, CHeneCoA is not an intermediate in the degradation of aromatic compounds in all other known anaerobic bacteria; consequently, degradation of CHC was mostly unknown in anaerobic bacteria. We identified a previously unknown CHC degradation pathway in the Fe(III)-reducing Geobacter metallireducens by determining the following CHC-induced in vitro activities: (i) the activation of CHC to CHCoA by a succinyl-CoA:CHC CoA transferase, (ii) the 1,2-dehydrogenation of CHCoA to CHeneCoA by CHCoA dehydrogenase, and (iii) the unusual 1,4-dehydrogenation of CHeneCoA to cyclohex-1,5-diene-1-carboxyl-CoA. This last represents a previously unknown joint intermediate of the CHC and aromatic compound degradation pathway in bacteria other than R. palustris. The enzymes catalyzing the three reactions were purified and characterized as specific enzymes after heterologous expression of the encoding genes. Quantitative reverse transcription-PCR revealed that expression of these genes was highly induced during growth with CHC but not with benzoate. The newly identified CHC degradation pathway is suggested to be present in nearly all CHC-degrading anaerobic bacteria, including denitrifying, Fe(III)-reducing, sulfate-reducing, and fermenting bacteria. Remarkably, all three CHC degradation pathways always link CHC catabolism to the catabolic pathways of aromatic compounds. We propose that the capacity to use CHC as a carbon source evolved from already-existing aromatic compound degradation pathways. Copyright © 2014, American Society for Microbiology. All Rights Reserved.

Enzymes Involved in a Novel Anaerobic Cyclohexane Carboxylic Acid Degradation Pathway

PubMed Central

Kung, Johannes W.; Meier, Anne-Katrin; Mergelsberg, Mario

2014-01-01

The anaerobic degradation of cyclohexane carboxylic acid (CHC) has so far been studied only in Rhodopseudomonas palustris, in which CHC is activated to cyclohexanoyl coenzyme A (cyclohexanoyl-CoA [CHCoA]) and then dehydrogenated to cyclohex-1-ene-1-carboxyl-CoA (CHeneCoA). This intermediate is further degraded by reactions of the R. palustris-specific benzoyl-CoA degradation pathway of aromatic compounds. However, CHeneCoA is not an intermediate in the degradation of aromatic compounds in all other known anaerobic bacteria; consequently, degradation of CHC was mostly unknown in anaerobic bacteria. We identified a previously unknown CHC degradation pathway in the Fe(III)-reducing Geobacter metallireducens by determining the following CHC-induced in vitro activities: (i) the activation of CHC to CHCoA by a succinyl-CoA:CHC CoA transferase, (ii) the 1,2-dehydrogenation of CHCoA to CHeneCoA by CHCoA dehydrogenase, and (iii) the unusual 1,4-dehydrogenation of CHeneCoA to cyclohex-1,5-diene-1-carboxyl-CoA. This last represents a previously unknown joint intermediate of the CHC and aromatic compound degradation pathway in bacteria other than R. palustris. The enzymes catalyzing the three reactions were purified and characterized as specific enzymes after heterologous expression of the encoding genes. Quantitative reverse transcription-PCR revealed that expression of these genes was highly induced during growth with CHC but not with benzoate. The newly identified CHC degradation pathway is suggested to be present in nearly all CHC-degrading anaerobic bacteria, including denitrifying, Fe(III)-reducing, sulfate-reducing, and fermenting bacteria. Remarkably, all three CHC degradation pathways always link CHC catabolism to the catabolic pathways of aromatic compounds. We propose that the capacity to use CHC as a carbon source evolved from already-existing aromatic compound degradation pathways. PMID:25112478

DOM composition and transformation in boreal forest soils: The effects of temperature and organic-horizon decomposition state

USGS Publications Warehouse

O’Donnell, Jonathan A.; Aiken, George R.; Butler, Kenna D.; Guillemette, Francois; Podgorski, David C.; Spencer, Robert G. M.

2016-01-01

The boreal region stores large amounts of organic carbon (C) in organic-soil horizons, which are vulnerable to destabilization via warming and disturbance. Decomposition of soil organic matter (SOM) contributes to the production and turnover of dissolved organic matter (DOM). While temperature is a primary control on rates of SOM and DOM cycling, little is known about temperature effects on DOM composition in soil leachate. Here we conducted a 30 day incubation to examine the effects of temperature (20 versus 5°C) and SOM decomposition state (moss versus fibric versus amorphous horizons) on DOM composition in organic soils of interior Alaska. We characterized DOM using bulk dissolved organic C (DOC) concentration, chemical fractionation, optical properties, and ultrahigh-resolution mass spectrometry. We observed an increase in DOC concentration and DOM aromaticity in the 20°C treatment compared to the 5°C treatment. Leachate from fibric horizons had higher DOC concentration than shallow moss or deep amorphous horizons. We also observed chemical shifts in DOM leachate over time, including increases in hydrophobic organic acids, polyphenols, and condensed aromatics and decreases in low-molecular weight hydrophilic compounds and aliphatics. We compared ultrahigh-resolution mass spectrometry and optical data and observed strong correlations between polyphenols, condensed aromatics, SUVA254, and humic-like fluorescence intensities. These findings suggest that biolabile DOM was preferentially mineralized, and the magnitude of this transformation was determined by kinetics (i.e., temperature) and substrate quality (i.e., soil horizon). With future warming, our findings indicate that organic soils may release higher concentrations of aromatic DOM to aquatic ecosystems.

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...

Organics Captured from Comet Wild 2 by the Stardust Spacecraft

NASA Technical Reports Server (NTRS)

Sandford, Scott A.; Aleon, Jerome; Araki, Tohru; Bajt, Sasa; Baratta, Giuseppe A.; Borg, Janet; Brucato, John R.; Burchell, Mark J.; Busemann, Henner; Butterworth, Anna;

Polycyclic aromatic hydrocarbons in sediments and mussels of Corral Bay, south central Chile.

PubMed

Palma-Fleming, Hernan; P, Adalberto J Asencio; Gutierrez, Elena

2004-03-01

PAHs were measured in sediments and mussels (Mytilus chilensis) from Carboneros and Puerto Claro, located in Corral Bay, Valdivia. According to the ratio of phenanthrene/anthracene and fluoranthene/pyrene concentrations, these sites are medium polluted with PAHs originating mainly from pyrolytic sources. Fluoranthene was the major component measured in mussels (3.1-390 ng g(-1) dry weight) and sediments (6.9-74.1 ng g(-1) dry weight). In general, mussels were mainly exposed to the dissolved fraction of the lower molecular weight PAHs (tri- and tetra-aromatics) while the higher molecular ring systems (penta- and hexa-aromatics) were more bioavailable to sediments. Mussel PAHs content was relatively constant, with the exception of the 1999 summer season (March), when higher concentration values were found in both sites; however, PAHs residues in sediments showed a temporal variation.

Aromaticity and Antiaromaticity in Zintl Clusters

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sun, Zhong -Ming; Liu, Chao; Popov, Ivan Aleksandrovich

Originally, the concepts of aromaticity and antiaromaticity were introduced to explain the stability and reactivity of unsaturated organic compounds. Since then, they have been extended to other species with delocalized electrons including various saturated systems, organometallic compounds, and even inorganic clusters and molecules. In this study, we focus on the most recent progress of using these concepts to guide experimental synthesis and rationalize geometrical and electronic structures of a particular family of polyanions composed of Group 14 and 15 elements, namely Zintl clusters.

Aromaticity and Antiaromaticity in Zintl Clusters

DOE PAGES

Sun, Zhong -Ming; Liu, Chao; Popov, Ivan Aleksandrovich; ...

2018-05-18

Originally, the concepts of aromaticity and antiaromaticity were introduced to explain the stability and reactivity of unsaturated organic compounds. Since then, they have been extended to other species with delocalized electrons including various saturated systems, organometallic compounds, and even inorganic clusters and molecules. In this study, we focus on the most recent progress of using these concepts to guide experimental synthesis and rationalize geometrical and electronic structures of a particular family of polyanions composed of Group 14 and 15 elements, namely Zintl clusters.

Radiation-resistant, amorphous, all-aromatic poly(arylene ether sulfones) - Synthesis, physical behavior, and degradation characteristics

NASA Technical Reports Server (NTRS)

Lewis, D. A.; O'Donnell, James H.; Hedrick, J. L.; Ward, T. C.; Mcgrath, J. E.

1989-01-01

The effects of Co-60 gamma radiation on a series of poly(arylene ether sulfones) prepared by nucleophilic activated aromatic substitution are investigated experimentally. The preparation of the test compounds is described, and the test results are presented in extensive tables and graphs. Radiation-induced degradation, as measured by SO2 production, was found to be lowest in compounds based on biphenol rather than bisphenol A; these findings were also well correlated with ultimate-tensile-strain measurements.

Molecular Characterization of Thiols in Fossil Fuels by Michael Addition Reaction Derivatization and Electrospray Ionization Fourier Transform Ion Cyclotron Resonance Mass Spectrometry.

PubMed

Wang, Meng; Zhao, Suoqi; Liu, Xuxia; Shi, Quan

2016-10-04

Thiols widely occur in sediments and fossil fuels. However, the molecular composition of these compounds is unclear due to the lack of appropriate analytical methods. In this work, a characterization method for thiols in fossil fuels was developed on the basis of Michael addition reaction derivatization followed by electrospray ionization Fourier transform ion cyclotron resonance mass spectrometry (ESI FT-ICR MS). Model thiol compound studies showed that thiols were selectively reacted with phenylvinylsulfone and transformed to sulfones with greater than 98% conversions. This method was applied to a coker naphtha, light and heavy gas oils, and crude oils from various geological sources. The results showed that long alkyl chain thiols are readily present in petroleum, which have up to 30 carbon atoms. Large DBE dispersity of thiols indicates that naphthenic and aromatic thiols are also present in the petroleum. This method is capable of detecting thiol compounds in the part per million range by weight. This method allows characterization of thiols in a complex hydrocarbon matrix, which is complementary to the comprehensive analysis of sulfur compounds in fossil fuels.

Peracetic Acid Depolymerization of Biorefinery Lignin for Production of Selective Monomeric Phenolic Compounds.

PubMed

Ma, Ruoshui; Guo, Mond; Lin, Kuan-Ting; Hebert, Vincent R; Zhang, Jinwen; Wolcott, Michael P; Quintero, Melissa; Ramasamy, Karthikeyan K; Chen, Xiaowen; Zhang, Xiao

2016-07-25

Lignin is the largest source of renewable material with an aromatic skeleton. However, due to the recalcitrant and heterogeneous nature of the lignin polymer, it has been a challenge to effectively depolymerize lignin and produce high-value chemicals with high selectivity. In this study, a highly efficient lignin-to-monomeric phenolic compounds (MPC) conversion method based on peracetic acid (PAA) treatment was reported. PAA treatment of two biorefinery lignin samples, diluted acid pretreated corn stover lignin (DACSL) and steam exploded spruce lignin (SESPL), led to complete solubilization and production of selective hydroxylated monomeric phenolic compounds (MPC-H) and monomeric phenolic acid compounds (MPC-A) including 4-hydroxy-2-methoxyphenol, p-hydroxybenzoic acid, vanillic acid, syringic acid, and 3,4-dihydroxybenzoic acid. The maximized MPC yields obtained were 18 and 22 % based on the initial weight of the lignin in SESPL and DACSL, respectively. However, we found that the addition of niobium pentoxide catalyst to PAA treatment of lignin can significantly improve the MPC yields up to 47 %. The key reaction steps and main mechanisms involved in this new lignin-to-MPC valorization pathway were investigated and elucidated. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Peracetic Acid Depolymerization of Biorefinery Lignin for Production of Selective Monomeric Phenolic Compounds

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ma, Ruoshui; Guo, Mond; Lin, Kuan-ting

Lignin is the largest source of renewable material with an aromatic skeleton. However, due to the recalcitrant and heterogeneous nature of the lignin polymer, it has been a challenge to effectively depolymerize lignin and produce high-value chemicals with high selectivity. In this study, a highly efficient lignin-to-monomeric phenolic compounds (MPC) conversion method based on peracetic acid (PAA) treatment was reported. PAA treatment of two biorefinery lignin samples, diluted acid pretreated corn stover lignin (DACSL) and steam exploded spruce lignin (SESPL), led to complete solubilization and production of selective hydroxylated monomeric phenolic compounds (MPC-H) and monomeric phenolic acid compounds (MPC-A) includingmore » 4-hydroxy-2-methoxyphenol, p-hydroxybenzoic acid, vanillic acid, syringic acid, and 3,4-dihydroxybenzoic acid. The maximized MPC yields obtained were 18 and 22 % based on the initial weight of the lignin in SESPL and DACSL, respectively. However, we found that the addition of niobium pentoxide catalyst to PAA treatment of lignin can significantly improve the MPC yields up to 47 %. The key reaction steps and main mechanisms involved in this new lignin-to-MPC valorization pathway were investigated and elucidated.« less

Aromatic Diimides - Potential Dyes for Use in Smart Films and Fibers

NASA Technical Reports Server (NTRS)

Meador, Michael A.; Tyson, Daniel S.; Ilhan, Faysal; Carbaugh, Ashley

2008-01-01

New aromatic diimide fluorescent dyes have been prepared with potential for use as chemical sensors and in chromogenic polymers. These dyes have been designed to utilize excited state electron transfer reactions as the means for sensing chemical species. For example, an aniline en-dcapped anthryl diimides functions effectively as an "on-off" sensor for pH and the detection of phosphoryl halide based chemical warfare agents, such as Sarin. In the absence of analytes, fluorescence from this dye is completely quenched by excited state electron transfer from the terminal amines. Reaction of these amines inhibits electron transfer and activates the fluorescence of the dye. Another substituted anthryl diimide is presented with the capability to detect pH and nitroaromatic compounds, such as TNT. Films prepared by doping small amounts (less than 0.1 weight percent) of several of these dyes in polymers such as linear low density polyethylene exhibit thermochromism. At room temperature, these films fluoresce reddish-orange. Upon heating, the fluorescence turns green. This process is reversible cooling the films to room temperature restores the orange emission.

Sol-gel coated ion sources for liquid chromatography-direct electron ionization mass spectrometry.

PubMed

Riboni, Nicolò; Magrini, Laura; Bianchi, Federica; Careri, Maria; Cappiello, Achille

2017-07-25

Advances in interfacing liquid chromatography and electron ionization mass spectrometry are presented. New ion source coatings synthesized by sol-gel technology were developed and tested as vaporization surfaces in terms of peak intensity, peak width and peak delay for the liquid chromatography-direct electron ionization mass spectrometry (Direct-EI) determination of environmental pollutants like polycyclic aromatic hydrocarbons and steroids. Silica-, titania-, and zirconia-based coatings were sprayed inside the stainless steel ion source and characterized in terms of thermal stability, film thickness and morphology. Negligible weight losses until 350-400 °C were observed for all the materials, with coating thicknesses in the 6 (±1)-11 (±2) μm range for optimal ionization process. The best performances in terms of both peak intensity and peak width were obtained by using the silica-based coating: the detection of the investigated compounds was feasible at low ng μl -1 levels with a good precision (RSD < 9% for polycyclic aromatic hydrocarbons and <11% for hormones). Copyright © 2017 Elsevier B.V. All rights reserved.

Persistent organic pollutants and polycyclic aromatic hydrocarbons in penguins of the genus Pygoscelis in Admiralty Bay - An Antarctic specially managed area.

PubMed

Montone, Rosalinda C; Taniguchi, Satie; Colabuono, Fernanda I; Martins, César C; Cipro, Caio Vinícius Z; Barroso, Hileia S; da Silva, Josilene; Bícego, Márcia C; Weber, Rolf R

2016-05-15

Persistent organic pollutants were assessed in fat samples of the Gentoo (Pygoscelis papua), Chinstrap (Pygoscelis antarcticus) and Adélie (Pygoscelis adeliae) penguins collected during the austral summers of 2005/06 and 2006/07 in Admiralty Bay, King George Island, Antarctica. The predominant organic pollutants were PCB (114 to 1115), polycyclic aromatic hydrocarbons (PAHs) (60.1 to 238.7), HCB (<0.3 to 132.2) and BDE-47 (<1.0 to 10.7) in ng g(-1) wet weight. The mean concentrations of the majority of organic pollutants were similar among the three species of penguins. Chicks of all three species showed similar profiles of PCB congeners, with predominance of lower chlorinated compounds. The distribution of PAHs was similar in all birds, with a predominance of naphthalene and alkyl-naphthalene, which are the main constituents of arctic diesel fuel. These data contribute to the monitoring of the continued exposure to organic pollutants in the Antarctic biota. Copyright © 2016 Elsevier Ltd. All rights reserved.

Carbonyl reductase of dog liver: purification, properties, and kinetic mechanism.

PubMed

Hara, A; Nakayama, T; Deyashiki, Y; Kariya, K; Sawada, H

1986-01-01

A carbonyl reductase has been extracted into 0.5 M KCl from dog liver and purified to apparent homogeneity by a three-step procedure consisting of chromatography on CM-Sephadex, Matrex green A, and Sephadex G-100 in high-ionic-strength buffers. The enzyme is a dimer composed of two identical subunits of molecular weight 27,000. The pH optimum is 5.5 and the isoelectric point of the enzyme is 9.3. The enzyme reduces aromatic ketones and aldehydes; the aromatic ketones with adjacent medium alkyl chains are the best substrates. Quinones, ketosteroids, prostaglandins, and aliphatic carbonyl compounds are poor or inactive substrates for the enzyme. As a cofactor the enzyme utilizes NADPH, the pro-S hydrogen atom of which is transferred to the substrate. Two moles of NADPH bind to one mole of the enzyme molecule, causing a blue shift and enhancement of the cofactor fluorescence. The reductase reaction is reversible and the equilibrium constant determined at pH 7.0 is 12.8. Steady-state kinetic measurements in both directions suggest that the reaction proceeds through a di-iso ordered bi-bi mechanism.

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.

Production and composition of pyrogenic dissolved organic matter from a logical series of laboratory-generated chars

NASA Astrophysics Data System (ADS)

Bostick, Kyle W.; Zimmerman, Andrew R.; Wozniak, Andrew. S.; Mitra, Siddhartha; Hatcher, Patrick G.

2018-04-01

Though pyrogenic carbon (pyC) has been assumed to be predominantly stable, degradation and transfers of pyC between various pools have been found to influence its cycling and longevity in the environment. Dissolution via leaching may be the main control on loss processes such as microbial or abiotic oxidation, mineral sorption, or export to aquatic systems. Yet, little is known of the controls on pyrogenic dissolved organic matter (pyDOM) generation or composition. Here, the yield and composition of pyDOM generated through batch leaching of a thermal series of oak and grass biochars, as well as several non-pyrogenic reference materials, was compared to that of their parent solids. Over 17 daily leaching cycles, biochars made from oak at 250 to 650° C released decreasing amounts of C on both a weight (16.9 to 0.3%, respectively) and C yield basis (7.4 to 0.2% C, respectively). Aryl-C represented an estimated 32 to 82% of C in the parent solids (identified by 13C-NMR), but only 7 to 38% in the leachates (identified by 1H-NMR), though both increased with pyrolysis temperature. PyC, often operationally defined as condensed aromatic carbon (ConAC), was quantified using the benzenepolycarboxylic acid (BPCA) method. Tri- and tetra-carboxylated BPCAs were formed from non-pyrogenic reference materials, thus, only penta- and hexa-carboxylated BPCAs were used to derive a BPCA-C to ConAC conversion factor of 7.04. ConAC made up 24 to 57% of the pyrogenic solid C (excluding the 250 °C biochar), but only about 9 to 23% of their respective leachates' DOC, though both proportions generally increased with pyrolysis temperature. Weighted BPCA compound distributions, or the BPCA Aromatic Condensation (BACon) Index, indicate that ConAC cluster size increased in pyrogenic solids but not in leachates. Additional evidence presented suggests that both aromatic cluster size and O-containing functional group contents in the pyrogenic solid control pyC solubility. Overall, pyDOM was found to be compositionally dissimilar from its parent chars and contained a complex mixture of organic compound groups. Thus, it is expected that estimates of dissolved pyC production and export, made only by detection of ConAC, are too low by factors of 4 to 11.

Susceptibility of eastern oyster early life stages to road surface polycyclic aromatic hydrocarbons (PAHs).

DOT National Transportation Integrated Search

2012-06-01

Polycyclic aromatic hydrocarbons (PAHs) are a class of chemical compounds that are mostly : anthropogenic in nature, and they can become persistent organic contaminants in aquatic : ecosystems. Runoff from impervious surfaces is one of the many ways ...

CONTROL OF AROMATIC WASTE AIR STREAMS BY SOIL BIOREACTORS

EPA Science Inventory

Three soils were examined for the ability to degrade hydrocarbon vapors of benzene, toluene, ethylbenzene, and o-xylene (BTEX). Each of these compounds are major aromatic constituents of gasolines. The soils examined were Rubicon Sand from Traverse City, Michigan, Durant Loam fro...

Distribution of aliphatic hydrocarbons, polycyclic aromatic hydrocarbons and organochlorinated pollutants in deep-sea sediments of the Southern Cretan margin, Eastern Mediterranean Sea: a baseline assessment.

PubMed

Mandalakis, Manolis; Polymenakou, Paraskevi N; Tselepides, Anastasios; Lampadariou, Nikolaos

2014-07-01

Deep sediments from the southern Cretan margin were analyzed to establish baseline levels for various types of organic pollutants before the anticipated intensification of anthropogenic activities. The total concentration of aliphatic hydrocarbons (ΣAH:326-3758ngg(-1), dry weight) was similar to those reported for deep sediments of the western Mediterranean Sea, while considerably lower levels were measured for polycyclic aromatic hydrocarbons (ΣPAH:9-60ngg(-1)). Source-diagnostic ratios suggested that the aliphatic hydrocarbons in sediments were mainly of terrestrial biogenic origin, while polycyclic aromatic hydrocarbons stemmed from the deposition of long-range transported combustion aerosols. Among the organochlorinated compounds analyzed, β-hexachlorocyclohexane (β-HCH:222-7052pgg(-1)), 1,1,1-trichloro-2,2-bis(4-chlorophenyl)ethane (p,p'-DDT:37-2236pgg(-1)) and polychlorinated biphenyls (ΣPCB:38-1182pgg(-1)) showed the highest abundance in sediments. The presence of HCHs and PCBs was attributed to historical inputs that have undergone extensive weathering, whereas an ongoing fresh input was suggested for p,p'-DDT. Multiple linear regression analysis revealed that the levels of the various pollutants in sediments were controlled by different factors, but with organic carbon content playing a prominent role in most cases. Copyright © 2014 Elsevier Ltd. All rights reserved.

[Characteristics of organic pollutants in the sediments from a typical electronics industrial zone].

PubMed

Liu, Jin; Deng, Dai-Yong; Xu, Mei-Ying; Sun, Guo-Ping

2013-03-01

In order to investigate the contamination status of organic pollutants in a river of a typical electrical equipment industrial area, Ronggui, Foshan, the sediments were sampled for the composition, concentration and occurrence analysis of organic pollutants. The polar and non-polar fractionation methods were employed for the fingerprint establishment of organic pollutants. One hundred and seventy-one of organic chemicals including ten categories of alkanes, alkenes, polycyclic aromatic hydrocarbons, benzene, heterocyclic compounds, phthalate esters, aldehydes, ketones, polar compounds, silicon-containing material as well as alkyl esters were examined. The number of different categories of the detected organic pollutants in a descending order was: alkanes > polar compounds > polycyclic aromatic hydrocarbons > aldehydes and ketones > heterocyclic compounds > benzene homologues, phthalate ester > alkyl esters > silicon material > olefins. The abundance of detected organic pollutants in a descending order was: alkanes > polar compounds > alkyl esters > olefins > polycyclic aromatic hydrocarbons > phthalates > silicon material > aldehydes and ketones > heterocyclic compounds > benzene homologues. Among the 51 kinds of alkanes detected, nonadecane accounted for 14.83%, and the persistent organic pollutants accounted for 2.33% of the total organic matter. Compared to similar studies, there were 51 kinds of alkanes and they accounted for 55.5% of the total organic chemicals, showing high diversity and abundance. In addition, some electronics industry-related organic pollutants such as silicone materials were also detected in high frequency.

Photocatalytic degradation of paracetamol: intermediates and total reaction mechanism.

PubMed

Moctezuma, Edgar; Leyva, Elisa; Aguilar, Claudia A; Luna, Raúl A; Montalvo, Carlos

2012-12-01

The advanced oxidation of paracetamol (PAM) promoted by TiO(2)/UV system in aqueous medium was investigated. Monitoring this reaction by HPLC and TOC, it was demonstrated that while oxidation of paracetamol is quite efficient under these conditions, its mineralization is not complete. HPLC indicated the formation of hydroquinone, benzoquinone, p-aminophenol and p-nitrophenol in the reaction mixtures. Further evidence of p-nitrophenol formation was obtained following the reaction by UV-vis spectroscopy. Continuous monitoring by IR spectroscopy demonstrated the breaking of the aromatic amide present in PAM and subsequent formation of several aromatic intermediate compounds such as p-aminophenol and p-nitrophenol. These aromatic compounds were eventually converted into trans-unsaturated carboxylic acids. Based on these experimental results, an alternative deacylation mechanism for the photocatalytic oxidation of paracetamol is proposed. Our studies also demonstrated IR spectroscopy to be a useful technique to investigate oxidative mechanisms of pharmaceutical compounds. Copyright © 2012 Elsevier B.V. All rights reserved.

Stereodynamics and edge-to-face CH-π aromatic interactions in imino compounds containing heterocyclic rings.

PubMed

González-Rosende, M Eugenia; Castillo, Encarna; Jennings, W Brian; Malone, John F

2017-02-07

By comparison with close contact interactions between benzene rings there is a paucity of experimental data available for attractive interactions involving aromatic heterocyclic rings, especially for small molecules in solution. Herein we describe aromatic heterocyclic and carbocyclic edge-to face interactions and conformational stereodynamics of N-1,2-diphenylethyl imines bearing a phenyl group and either a 2-pyridyl, 3-pyridyl, 2-thiophene or 2-furanyl moiety on the imino carbon. X-ray crystal structures have been determined for two compounds. Slow rotation about the phenyl-imino bond in the E-isomers and around the heterocycle-imino bond in the Z-isomers of the pyridyl compounds was observed at low temperatures by NMR. Abnormally large shielding of one ortho hydrogen indicates that both the imino phenyl and heterocycle rings can engage in an edge-to-face interaction with the N-terminal phenyl moiety in the appropriate isomer. Some rotational barriers around the phenyl-imino and heterocycle-imino bonds were measured.

In situ growth of monodispersed Fe3O4 nanoparticles on graphene for the removal of heavy metals and aromatic compounds.

PubMed

Wu, Hai-Xia; Wu, Jia-Wei; Niu, Zhi-Gang; Shang, Xiu-Li; Jin, Jun

2013-01-01

We report on the efficient removal of heavy metal ions and aromatic compounds from simulated wastewater with a nanocomposite. The nanocomposite was obtained via thermal decomposition of the precursor Fe(acac)3 onto the surface of graphene, modified by diethylenetriamine pentaacetic anhydride through dopamine. It was found that the maximum adsorption capacity of the nanocomposite toward Cu(2+) and naphthalene was 207.9 and 72.2 mg g(-1) respectively, displaying a high efficiency for the removal of heavy metal ions as well as aromatic compounds at pH 7.0 and 293 K. The Langmuir for naphthalene and the Freundlich for the Cu(2+) adsorption isotherms were applicable for describing the removal processes. Furthermore, the nanocomposite was carefully examined by transmission electron microscopy, Fourier transform infrared spectroscopy, X-ray diffraction, Raman spectra, and UV-vis spectroscopy. This work provides a very efficient, fast and convenient approach to exploring a promising nanocomposite for water treatment.

In Vitro Antifungal Activity of New and Known Geranylated Phenols against Phytophthora cinnamomi Rands.

PubMed

Chavez, María I; Soto, Mauricio; Cimino, Franco A; Olea, Andrés F; Espinoza, Luis; Díaz, Katy; Taborga, Lautaro

2018-05-29

A series of new and known geranylated phenol/methoxyphenol derivatives has been tested in vitro as inhibitor agents of mycelial growth of Phytophthora cinnamomi . The activity of tested compounds is correlated with the nature, number, and position of the substituent group on the aromatic ring. Results indicate that the most active geranylated derivatives are those having two hydroxyl groups (or one ⁻OH and one ⁻OCH₃) attached to the aromatic ring. Interestingly, these derivatives are as active as Metalaxil ® , a commonly used commercial fungicide. Thus, our results suggest that some of these compounds might be of agricultural interest due to their potential use as fungicides against P. cinnamomi . The effect of structure on fungicide activity is discussed in terms of electronic distribution on both the aromatic ring and side geranyl chain. All tested compounds have been synthesized by direct coupling of geraniol and the respective phenol. Interestingly, new digeranylated derivatives were obtained by increasing the reaction time.

Synthesis and electronic factors in thermal cyclodimerization of functionalized aromatic trifluorovinyl ethers.

PubMed

Spraul, Bryan K; Suresh, S; Jin, Jianyong; Smith, Dennis W

2006-05-31

A series of 19 p-substituted aromatic trifluorovinyl ether compounds were prepared from versatile intermediate p-Br-C(6)H(4)-O-CF=CF(2) and underwent thermal radical mediated cyclodimerization to new difunctional compounds containing the 1,2-disubstituted perfluorocyclobutyl (PFCB) linkage. The synthetic scope demonstrates the functional group transformation tolerance of the fluorovinyl ether, and the dimers are useful as monomers for traditional step-growth polymerization methods. (19)F NMR spectra confirmed that p-substitution affects the trifluorovinyl ether group chemical shifts. The first kinetic studies and substituent effects on thermal cyclodimerization were performed, and the results indicated that electron-withdrawing groups slow the rate of cyclodimerization. The data were further analyzed using the Hammett equation, and reaction constants (rho) of -0.46 at 120 degrees C and -0.59 at 130 degrees C were calculated. This study presents the first liner free energy relationship reported for the cyclodimerization of aromatic trifluorovinyl ethers to PFCB compounds.

CHEMISTRY OF OXIDATION OF POLYCYCLIC AROMATIC HYDROCARBONS BY SOIL PSEUDOMONADS

PubMed Central

Rogoff, Martin H.

1962-01-01

Rogoff, Martin H. (U.S. Bureau of Mines, Pittsburgh, Pa.). Oxidation of polycyclic aromatic hydrocarbons by soil pseudomonads. J. Bacteriol. 83:998–1004. 1962.—Substitution of phenanthrene by a methyl group at the 9-carbon blocks oxidation of the compound by a resting-cell suspension of a phenanthrene-grown soil pseudomonad. When 2-methylphenanthrene is provided, the oxidation rate is considerably higher; 3-methylphenanthrene is oxidized at a rate intermediate between the other two, even though the methyl group is attached to a carbon directly involved in ring splitting. Cells grown on naphthalene or anthracene oxidize phenanthrene at a much lower rate than cells grown with phenanthrene or 2-methylnaphthalene as the source of carbon. Naphthalene-grown cells also absorb less phenanthrene from aqueous solution than do their phenanthrene-grown counterparts. The data are in keeping with the hypothesis that polynuclear aromatic hydrocarbons attach to the relevant bacterial enzymes at carbon-carbon bonds of high electron density (K regions; localized double bonds), and that the ring-splitting reactions then occur at other bonds on the substrate molecule. The actual bond that undergoes fission is determined by the electronic and steric configurations of the enzyme-substrate complex. When linearly arranged aromatic compounds such as naphthalene or anthracene are attacked, attachment to an enzyme and ring splitting may take place on the same ring; angular aromatic compounds such as phenanthrene afford attachment to an enzyme at a bond in a ring other than the one containing the ring-splitting site. PMID:14493381

Characteristic analysis for odor gas emitted from food waste anaerobic fermentation in the pretreatment workshop.

PubMed

Di, Yanqiang; Liu, Jiemin; Liu, Jianguo; Liui, Siyuan; Yan, Luchun

2013-10-01

Gas chromatography-mass spectrometry, olfactometry, and other related methods were applied for the qualitative and quantitative analysis of the characteristics of odorous gases in the pretreatment workshop. The composition of odorous gases emitted from municipal food waste was also investigated in this study. The results showed that the tested gases are mainly composed of aromatic gases, which account for 49% of the total volatile organic compounds (VOC) concentrations. The nitrogenous compounds comprise 15% of the total concentration and the other gases comprise the remaining 36%. The level of odor concentration ranged from 2523 odor units (OU) m(-3) to 3577 OU m(-3). The variation of the total chemical composition ranged from 19,725 microg m(-3) to 24,184 microg m(-3). Among the selected four sampling points, the discharge outlet was detected to have the highest concentration in terms of odor, total chemical, sulfur compounds, and aromatics. The correlation analysis showed that the odor concentrations were evidently related to the total chemical composition, sulfur compounds, and aromatics (P < 0.05, n = 5). The odor activity value analysis identified the top three compounds, hydrogen sulfide (91.8), ethyl sulfide (35.8), and trimethylamine (70.6), which contribute to air pollution complaint of waste materials.

Dielectric barrier discharge ionization for liquid chromatography/mass spectrometry.

PubMed

Hayen, Heiko; Michels, Antje; Franzke, Joachim

2009-12-15

An atmospheric pressure microplasma ionization source based on a dielectric barrier discharge with a helium plasma cone outside the electrode region has been developed for liquid chromatography/mass spectrometry (LC/MS). For this purpose, the plasma was realized in a commercial atmospheric pressure ionization source. Dielectric barrier discharge ionization (DBDI) was compared to conventional electrospray ionization (ESI), atmospheric pressure chemical ionization (APCI), and atmospheric pressure photoionization (APPI) in the positive ionization mode. Therefore, a heterogeneous compound library was investigated that covered polar compounds such as amino acids, water-soluble vitamins, and nonpolar compounds like polycyclic aromatic hydrocarbons and functionalized hydrocarbons. It turned out that DBDI can be regarded as a soft ionization technique characterized by only minor fragmentation similar to APCI. Mainly protonated molecules were detected. Additionally, molecular ions were observed for polycyclic aromatic hydrocarbons and derivatives thereof. During DBDI, adduct formation with acetonitrile occurred. For aromatic compounds, addition of one to four oxygen atoms and to a smaller extend one nitrogen and oxygen was observed which delivered insight into the complexity of the ionization processes. In general, compounds covering a wider range of polarities can be ionized by DBDI than by ESI. Furthermore, limits of detection compared to APCI are in most cases equal or even better.

Lipophilic extracts of Cynara cardunculus L. var. altilis (DC): a source of valuable bioactive terpenic compounds.

PubMed

Ramos, Patrícia A B; Guerra, Ângela R; Guerreiro, Olinda; Freire, Carmen S R; Silva, Artur M S; Duarte, Maria F; Silvestre, Armando J D

2013-09-04

Lipophilic extracts of Cynara cardunculus L. var. altilis (DC) from the south of Portugal (Baixo Alentejo) were studied by gas chromatography-mass spectrometry. One sesquiterpene lactone, four pentacyclic triterpenes, and four sterols were reported for the first time as cultivated cardoon components, namely, deacylcynaropicrin, β- and α-amyrin, lupenyl and ψ-taraxasteryl acetates, stigmasterol, 24-methylenecholesterol, campesterol, and Δ(5)-avenasterol. In addition, other new compounds were identified: ten fatty acids, eight long-chain aliphatic alcohols, and six aromatic compounds. Four triterpenyl fatty acid esters were also detected. Sesquiterpene lactones and pentacyclic triterpenes were the major lipophilic families, representing respectively 2-46% and 10-89% of the detected compounds. Cynaropicrin was the most abundant sesquiterpene lactone, while taraxasteryl acetate was the main pentacyclic triterpene. Fatty acids and sterols, mainly hexadecanoic acid and β-sitosterol, were present at lower amounts (1-20% and 1-11% of the detected compounds). Long-chain aliphatic alcohols and aromatic compounds were detected at reduced abundances (1-6% of the detected compounds).

Spatial distribution of polycyclic aromatic hydrocarbon and polychlorinated biphenyl sources in the Nakdong River Estuary, South Korea.

PubMed

Lee, Jun H; Woo, Han J; Jeong, Kap S; Kang, Jeong W; Choi, Jae U; Jeong, Eun J; Park, Kap S; Lee, Dong H

2017-10-15

Our research team investigated the elemental composition and the presence of various toxic organic compounds, such as polycyclic aromatic hydrocarbons (PAHs) and polychlorinated biphenyls (PCBs), in estuary surface sediments to trace the spatial distribution of the sources of pollution deposited in Nakdong River, Busan, South Korea. The spatial patterns of elemental composition and toxic organic compounds were determined from the measurements of total organic carbon (TOC), total nitrogen, total sulfur, PAHs, and PCBs. The sediments had TOC contents of between 0.02 and 1.80 wt% (avg. 0.34 wt%), depending on the amount of clay-sized particles. The concentrations of PAHs and PCBs (10.8-167.7 ng g -1 dry wt and 197.0-754.0 pg g -1 dry wt, respectively) in surface sediments revealed different spatial patterns for these compounds, suggesting that they partially originated from the combustion of fossil fuels and from the use of commercial PCB products at adjacent industrial complexes. Although these concentrations were far below the Sediment Quality Guideline (SQG) of the National Oceanic and Atmospheric Administration (NOAA), the sediments at one site contained PCBs at concentrations close to the response level (754.0 pg g -1 dry wt), and were dominated by low-molecular-weight PAHs. The PAHs and PCBs in Nakdong River Estuary sediments were likely to have originated from the combustion of fossil fuels and biomass at the adjacent industrial complexes. The primarily analyzed results determined that PAHs originated from the combustion of fossil fuels and biomass, and overall concentrations were related to the contributions of individual PAHs in most sediment samples. Based on the SQG of the NOAA, our results indicate that the anthropogenic activity should be considered on the future-sustainable management of this estuary system.

AROMATIC AMINES IN AND NEAR THE BUFFALO RIVER

EPA Science Inventory

Three sediment samples taken from the Buffalo River and two soil samples taken near its bank have been analyzed for 2-propanol-extractable, basic organic compounds by using GC/MS. Eleven aromatic amines related to the commercial production of malachite green and crystal violet we...

QSAR Study for Carcinogenic Potency of Aromatic Amines Based on GEP and MLPs

PubMed Central

Song, Fucheng; Zhang, Anling; Liang, Hui; Cui, Lianhua; Li, Wenlian; Si, Hongzong; Duan, Yunbo; Zhai, Honglin

2016-01-01

A new analysis strategy was used to classify the carcinogenicity of aromatic amines. The physical-chemical parameters are closely related to the carcinogenicity of compounds. Quantitative structure activity relationship (QSAR) is a method of predicting the carcinogenicity of aromatic amine, which can reveal the relationship between carcinogenicity and physical-chemical parameters. This study accessed gene expression programming by APS software, the multilayer perceptrons by Weka software to predict the carcinogenicity of aromatic amines, respectively. All these methods relied on molecular descriptors calculated by CODESSA software and eight molecular descriptors were selected to build function equations. As a remarkable result, the accuracy of gene expression programming in training and test sets are 0.92 and 0.82, the accuracy of multilayer perceptrons in training and test sets are 0.84 and 0.74 respectively. The precision of the gene expression programming is obviously superior to multilayer perceptrons both in training set and test set. The QSAR application in the identification of carcinogenic compounds is a high efficiency method. PMID:27854309

Aromaticity of benzene derivatives: an exploration of the Cambridge Structural Database.

PubMed

Majerz, Irena; Dziembowska, Teresa

2018-04-01

The harmonic oscillator model of aromaticity (HOMA) index, one of the most popular aromaticity indices for solid-state benzene rings in the Cambridge Structural Database (CSD), has been analyzed. The histograms of HOMA for benzene, for benzene derivatives with one formyl, nitro, amino or hydroxy group as well as the histograms for the derivatives with two formyl, nitro, amino or hydroxy groups in ortho, meta and para positions were investigated. The majority of the substituted benzene derivatives in the CSD are characterized by a high value of HOMA, indicating fully aromatic character; however, the distribution of the HOMA value from 1 to about 0 indicates decreasing aromaticity down to non-aromatic character. Among the benzene derivatives investigated, a significant decrease in aromaticity can be related to compounds with diamino and dinitro groups in the meta position.

Genetic determinant for amino acid metabolites and changes in body weight and insulin resistance in response to weight-loss diets: the Preventing Overweight Using Novel Dietary Strategies (POUNDS LOST) trial.

PubMed

Xu, Min; Qi, Qibin; Liang, Jun; Bray, George A; Hu, Frank B; Sacks, Frank M; Qi, Lu

2013-03-26

Circulating branched-chain amino acids and aromatic amino acids were recently related to insulin resistance and diabetes mellitus in prospective cohorts. We tested the effects of a genetic determinant of branched-chain amino acid/aromatic amino acid ratio on changes in body weight and insulin resistance in a 2-year diet intervention trial. We genotyped the branched-chain amino acid/aromatic amino acid ratio-associated variant rs1440581 near the PPM1K gene in 734 overweight or obese adults who were assigned to 1 of 4 diets varying in macronutrient content. At 6 months, dietary fat significantly modified genetic effects on changes in weight, fasting insulin, and homeostasis model assessment of insulin resistance (HOMA-IR) after adjustment for the confounders (all P for interaction ≤0.006). Further adjustment for weight change did not appreciably change the interactions for fasting insulin and HOMA-IR. In the high-fat diet group, the C allele was related to less weight loss and smaller decreases in serum insulin and HOMA-IR (all P ≤ 0.02 in an additive pattern), whereas an opposite genotype effect on changes in insulin and HOMA-IR was observed in the low-fat diet group (P=0.02 and P=0.04, respectively). At 2 years, the gene-diet interactions remained significant for weight loss (P=0.008) but became null for changes in serum insulin and HOMA-IR resulting from weight regain. Individuals carrying the C allele of the branched-chain amino acid/aromatic amino acid ratio-associated variant rs1440581 may benefit less in weight loss and improvement of insulin sensitivity than those without this allele when undertaking an energy-restricted high-fat diet. URL: http://www.clinicaltrials.gov. Unique identifier: NCT00072995.

Water-Sediment Partition of Polycyclic Aromatic Hydrocarbons (PAHs) in Nansi Lake

NASA Astrophysics Data System (ADS)

Zhang, Guizhai; Diao, Youjiang

2018-06-01

Based on field data of polycyclic aromatic hydrocarbons (PAHs) in water and sediment in Nansi Lake. The concentrations and the partitioning characteristic of PAHs in the water and sediment were studied. The lgKd of high molecular weight PAHs were higher than the low molecular weight PAHs. The most of PAHs Kd values were negligible correlated with TOC, soluble salt, clay and pH of the sediment in Nansi Lake.

Polycyclic aromatic hydrocarbons in soils and crops after irrigation of wastewater discharged from domestic sewage treatment plants.

PubMed

Chung, N J; Cho, J Y; Park, S W; Park, B J; Hwang, S A; Park, T I

2008-08-01

The effects of domestic wastewater application on the translocation and accumulation of polycyclic aromatic hydrocarbons (PAHs) in soil and crops (rice, lettuce, and barley) were investigated by Wagner's pot experiment. In the soils and crops after domestic wastewater irrigation, high-molecular weight PAHs (5 to 6 ring) were not detected, but low-molecular weight PAHs (3 to 4 ring) were only detected at trace levels.

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

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. Copyright © 2014 Elsevier B.V. All rights reserved.

Human Immunodeficiency Virus Type 1 cDNA Integration: New Aromatic Hydroxylated Inhibitors and Studies of the Inhibition Mechanism

PubMed Central

Farnet, C. M.; Wang, B.; Hansen, M.; Lipford, J. R.; Zalkow, L.; Robinson, W. E.; Siegel, J.; Bushman, F.

1998-01-01

Integration of the human immunodeficiency virus type 1 (HIV-1) cDNA is a required step for viral replication. Integrase, the virus-encoded enzyme important for integration, has not yet been exploited as a target for clinically useful inhibitors. Here we report on the identification of new polyhydroxylated aromatic inhibitors of integrase including ellagic acid, purpurogallin, 4,8,12-trioxatricornan, and hypericin, the last of which is known to inhibit viral replication. These compounds and others were characterized in assays with subviral preintegration complexes (PICs) isolated from HIV-1-infected cells. Hypericin was found to inhibit PIC assays, while the other compounds tested were inactive. Counterscreening of these and other integrase inhibitors against additional DNA-modifying enzymes revealed that none of the polyhydroxylated aromatic compounds are active against enzymes that do not require metals (methylases, a pox virus topoisomerase). However, all were cross-reactive with metal-requiring enzymes (restriction enzymes, a reverse transcriptase), implicating metal atoms in the inhibitory mechanism. In mechanistic studies, we localized binding of some inhibitors to the catalytic domain of integrase by assaying competition of binding by labeled nucleotides. These findings help elucidate the mechanism of action of the polyhydroxylated aromatic inhibitors and provide practical guidance for further inhibitor development. PMID:9736543

The Use of Modified Bentonite for Removal of Aromatic Organics from Contaminated Soil.

PubMed

Gitipour; Bowers; Bodocsi

1997-12-15

This study investigates the clay-aromatic interactions with a view to the use of bentonite clay for binding benzene, toluene, ethylbenzene, and o-xylene (BTEX compounds) in contaminated soils. BTEX compounds are the most toxic aromatic constituents of gasoline present in many underground storage tanks. Modified (organophilic) and ordinary bentonites are used to remove these organics. The organophilic bentonites are prepared by replacing the exchangeable inorganic cations present in bentonite particles with a quaternary ammonium salt. Various clay-to-soil ratios were applied to determine the efficiency of the modified bentonite in enhancing the cement-based solidification/stabilization (S/S) of BTEX contaminated soils. Toxicity characteristics leaching procedure (TCLP) tests were performed on soil samples to evaluate the leaching of the organics. In addition, X-ray diffraction analyses were conducted to assess the changes in the basal spacing of the clays as a result of their interaction with BTEX compounds. The findings of this study reveal that organophilic bentonite can act as a successful adsorbent for removing the aromatic organics from contaminated soil. Thus, this material is viable for enhancing the performance of cement-based S/S processes, as an adsorbent for petroleum spills, and for landfill liners and slurry walls. Copyright 1997 Academic Press.

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

Type of litter determines the formation and properties of charred material during wildfires

NASA Astrophysics Data System (ADS)

Chavez, Bruno; Fonturbel, M. Teresa; Salgado, Josefa; García-Oliva, Felipe; Vega, Jose A.; Merino, Agustin

2014-05-01

Wildfire is one of the most important disturbances all over the World, affecting both the amount and composition of forest floor and mineral soils. In comparison with unburnt areas, wildfire-affected forest floor usually shows lower contents of labile C compounds and higher concentrations of recalcitrant aromatic forms. These changes in composition can have important impact on biogeochemical cycles and therefore ecosystem functions. Although burning of different types of litter can lead to different amount and types of pyrogenic compounds, this aspect has not been evaluated yet. The effect of wildfire on SOM composition and stability were evaluated in five major types of non-wood litter in Mediterranean ecosystems: Pinus nigra, E. arborea, P. pinaster, U. europaeus and Eucalyptus globulus. In each of these ecosystems, forest floor samples from different soil burn severities were sampled. Soil burnt severities were based on visual signs of changes in forest floor and deposition of ash. Pyrogenic carbon quality were analysed using elementary analysis, solid-state 13 C nuclear magnetic resonance spectroscopy, Reflectance Infrared Fourier Transform (FTIR) and thermal analysis (simultaneous DSC-TG). The study showed that the different types of litter influenced the formation and characteristics of charred material. They differed in the temperature at which they start to be formed, the amounts of charred compounds and in their chemical composition. The resulting charred materials from the different litter, showed an important variability in the degree of carbonitation/aromatization. Unlike the biochar obtained through pyrolysis of woody sources, which contains exclusively aromatic structures, in the charred material produced in some litter, lignin, cellulose and even cellulose persist even in the high soil burnt severity. Coinciding with increases in aromatic contents, important decreases in atomic H/C and O/C ratios were recorded. However, the values found in some litters, were higher than 0.5, suggesting that low degree of carbonization/aromatization. Although burning also led to compounds of higher thermal recalcitrance (increases in T50 values), values recorded in some litters were lower than those measured in highly polycondensed aromatic compounds. The differences found among the different forest floor cannot be only attributable to the initial SOM composition of the litter. Other aspects, such as the different thermal sensitivity, flammability and different conditions during wildfire (temperatures, combustion duration, oxygen concentrations) could also have contributed.

Aroma characterization based on aromatic series analysis in table grapes

PubMed Central

Wu, Yusen; Duan, Shuyan; Zhao, Liping; Gao, Zhen; Luo, Meng; Song, Shiren; Xu, Wenping; Zhang, Caixi; Ma, Chao; Wang, Shiping

2016-01-01

Aroma is an important part of quality in table grape, but the key aroma compounds and the aroma series of table grapes remains unknown. In this paper, we identified 67 aroma compounds in 20 table grape cultivars; 20 in pulp and 23 in skin were active compounds. C6 compounds were the basic background volatiles, but the aroma contents of pulp juice and skin depended mainly on the levels of esters and terpenes, respectively. Most obviously, ‘Kyoho’ grapevine series showed high contents of esters in pulp, while Muscat/floral cultivars showed abundant monoterpenes in skin. For the aroma series, table grapes were characterized mainly by herbaceous, floral, balsamic, sweet and fruity series. The simple and visualizable aroma profiles were established using aroma fingerprints based on the aromatic series. Hierarchical cluster analysis (HCA) and principal component analysis (PCA) showed that the aroma profiles of pulp juice, skin and whole berries could be classified into 5, 3, and 5 groups, respectively. Combined with sensory evaluation, we could conclude that fatty and balsamic series were the preferred aromatic series, and the contents of their contributors (β-ionone and octanal) may be useful as indicators for the improvement of breeding and cultivation measures for table grapes. PMID:27487935

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

PubMed

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

2016-12-01

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

Adsorption of aromatic compounds from the biodegradation of azo dyes on activated carbon

NASA Astrophysics Data System (ADS)

Faria, P. C. C.; Órfão, J. J. M.; Figueiredo, J. L.; Pereira, M. F. R.

2008-03-01

The adsorption of three selected aromatic compounds (aniline, sulfanilic acid and benzenesulfonic acid) on activated carbons with different surface chemical properties was investigated at different solution pH. A fairly basic commercial activated carbon was modified by means of chemical treatment with HNO 3, yielding an acid activated carbon. The textural properties of this sample were not significantly changed after the oxidation treatment. Equilibrium isotherms of the selected compounds on the mentioned samples were obtained and the results were discussed in relation to their surface chemistry. The influence of electrostatic and dispersive interactions involved in the uptake of the compounds studied was evaluated. The Freundlich model was used to fit the experimental data. Higher uptakes are attained when the compounds are present in their molecular form. In general, adsorption was disfavoured by the introduction of oxygen-containing groups on the surface of the activated carbon.

Suspect screening of OH-PAHs and non-target screening of other organic compounds in wood smoke particles using HR-Orbitrap-MS.

PubMed

Avagyan, Rozanna; Åberg, Magnus; Westerholm, Roger

2016-11-01

Wood combustion has been shown to contribute significantly to emissions of polycyclic aromatic hydrocarbons and hydroxylated polycyclic aromatic hydrocarbons, compounds with toxic and carcinogenic properties. However, only a small number of hydroxylated polycyclic aromatic hydrocarbons have been determined in particles from wood combustion, usually compounds with available reference standards. In this present study, suspect and non-target screening strategies were applied to characterize the wood smoke particles from four different wood types and two combustion conditions with respect to hydroxylated polycyclic aromatic hydrocarbons and other organic compounds. In the suspect screening, 32 peaks corresponding to 12 monohydroxylated masses were tentatively identified by elemental composition assignments and matching of isotopic pattern and fragments. More than one structure was suggested for most of the measured masses. Statistical analysis was performed on the non-target screening data in order to single out significant peaks having intensities that depend on the wood type and/or combustion condition. Significant peaks were found in both negative and positive ionization modes, with unique peaks for each wood type and combustion condition, as well as a combination of both factors. Furthermore, structural elucidation of some peaks was done by comparing the spectra in the samples with spectra found in the spectral databases. Six compounds were tentatively identified in positive ionization mode, and 19 in negative ionization mode. The results in this present study demonstrate that there are significant overall differences in the chemistry of wood smoke particles that depends on both the wood type and the combustion condition used. Copyright © 2016 Elsevier Ltd. All rights reserved.

Novel Scheme for Biosynthesis of Aryl Metabolites from l-Phenylalanine in the Fungus Bjerkandera adusta

PubMed Central

Lapadatescu, Carmen; Giniès, Christian; Le Quéré, Jean-Luc; Bonnarme, Pascal

2000-01-01

Aryl metabolite biosynthesis was studied in the white rot fungus Bjerkandera adusta cultivated in a liquid medium supplemented with l-phenylalanine. Aromatic compounds were analyzed by gas chromatography-mass spectrometry following addition of labelled precursors (14C- and 13C-labelled l-phenylalanine), which did not interfere with fungal metabolism. The major aromatic compounds identified were benzyl alcohol, benzaldehyde (bitter almond aroma), and benzoic acid. Hydroxy- and methoxybenzylic compounds (alcohols, aldehydes, and acids) were also found in fungal cultures. Intracellular enzymatic activities (phenylalanine ammonia lyase, aryl-alcohol oxidase, aryl-alcohol dehydrogenase, aryl-aldehyde dehydrogenase, lignin peroxidase) and extracellular enzymatic activities (aryl-alcohol oxidase, lignin peroxidase), as well as aromatic compounds, were detected in B. adusta cultures. Metabolite formation required de novo protein biosynthesis. Our results show that l-phenylalanine was deaminated to trans-cinnamic acid by a phenylalanine ammonia lyase and trans-cinnamic acid was in turn converted to aromatic acids (phenylpyruvic, phenylacetic, mandelic, and benzoylformic acids); benzaldehyde was a metabolic intermediate. These acids were transformed into benzaldehyde, benzyl alcohol, and benzoic acid. Our findings support the hypothesis that all of these compounds are intermediates in the biosynthetic pathway from l-phenylalanine to aryl metabolites. Additionally, trans-cinnamic acid can also be transformed via β-oxidation to benzoic acid. This was confirmed by the presence of acetophenone as a β-oxidation degradation intermediate. To our knowledge, this is the first time that a β-oxidation sequence leading to benzoic acid synthesis has been found in a white rot fungus. A novel metabolic scheme for biosynthesis of aryl metabolites from l-phenylalanine is proposed. PMID:10742235

Molecular weight distribution of phosphorus fraction of aquatic dissolved organic matter.

PubMed

Ged, Evan C; Boyer, Treavor H

2013-05-01

This study characterized dissolved organic phosphorus (DOP) that is discharged from the Everglades Agricultural Area as part of the larger pool of aquatic dissolved organic matter (DOM). Whole water samples collected at the Everglades stormwater treat area 1 West (STA-1 W) were fractionated using a batch ultrafiltration method to separate organic compounds based on apparent molecular weight (AMW). Each AMW fraction of DOM was characterized for phosphorus, carbon, nitrogen, UV absorbance, and fluorescence. The DOP content of the Everglades water matrix was characteristically variable constituting 4-56% of total phosphorus (TP) and demonstrated no correlation with dissolved organic carbon (DOC). Measured values for DOP exceeded 14μgL(-1) in four out of five sampling dates making phosphorus load reductions problematic for the stormwater treatment areas (STAs), which target inorganic phosphorus and have a goal of 10μgL(-1) as TP. The molecular weight distributions revealed 40% of DOP is high molecular weight, aromatic-rich DOM. The results of this research are expected to be of interest to environmental chemists, environmental engineers, and water resources managers because DOP presents a major obstacle to achieving TP levels <10μgL(-1). Copyright © 2013 Elsevier Ltd. All rights reserved.

Mutagenicity of diesel exhaust particle extracts: influence of fuel composition in two diesel engines

DOE Office of Scientific and Technical Information (OSTI.GOV)

Clark, C.R.; Henderson, T.R.; Royer, R.E.

The influence of diesel fuel composition on mutagenicity of exhaust particle associated organic compounds has been investigated using nine fuels varying in aromatic content and distillation properties. The tests were conducted with Oldsmobile Delta-88 and Peugot 504 diesel cars operated according to the EPA Federal Test Procedure. The particulate exhaust from each test was collected on a filter, extracted in dichloromethane and the resulting extract evaluated for mutagenicity in Salmonella strain TA-100. Mutagenicity of extracts of particles collected from the Oldsmobile were highest in the higher aromatic content fuels (> 30%) but similar for intermediate (20%) and low (13%) aromaticmore » content fuels. No influence of aromaticity on mutagenicity was observed in samples collected from the Peugeot under the same conditions. Thus, fuel aromatic content may enhance the production of mutagenic combustion products at higher concentrations, but may be dependent upon engine type. A good correlation was observed between mutagenicity of the particle extracts and the initial boiling point of the fuel (r = 0.89). Gas chromatography/mass spectrometric analysis of the aromatic fraction of the fuels showed that the fuel producing the most mutagenic combustion products was highest in phenanthrene type compounds.« less

The formation of quasi-alicyclic rings in alkyl-aromatic compounds

NASA Astrophysics Data System (ADS)

Straka, Pavel; Buryan, Petr; Bičáková, Olga

2018-02-01

The alkyl side chains of n-alkyl phenols, n-alkyl benzenes and n-alkyl naphthalenes are cyclised, as demonstrated by GC measurements, FTIR spectroscopy and molecular mechanics calculations. Cyclisation occurs due to the intramolecular interaction between an aromatic ring (-δ) and a hydrogen of the terminal methyl group (+δ) of an alkyl chain. In fact, conventional molecules are not aliphatic-aromatic, but quasi-alicyclic-aromatic. With the aromatic molecules formed with a quasi-alicyclic ring, the effect of van der Waals attractive forces increases not only intramolecularly but also intermolecularly. This effect is strong in molecules with propyl and higher alkyl substituents. The increase of intermolecular van der Waals attractive forces results in bi-linearity in the GC retention time of the compounds in question, observed in the dependence of the logarithm of the relative retention time on the number of carbons in a molecule in both polar and nonpolar stationary phases with both capillary and packed columns. The role of van der Waals forces has been demonstrated using the potential energies of covalent and noncovalent interactions for 2-n-alkyl phenols, n-alkyl benzenes and 1-n-alkyl- and 2-n-alkyl naphthalenes.

Infrared Spectroscopy of Matrix-Isolated Polycyclic Aromatic Nitrogen Heterocycles (PANHs)

NASA Technical Reports Server (NTRS)

Mattioda, A. L.; Hudgins, D. M.; Bauschlicher, C. W.; Allamandola, L. J.; Biemesderfer, C. D.; Rosi, M.

2002-01-01

The mid-infrared spectra of the nitrogen-containing heterocyclic polycyclic aromatic compounds 1-azabenz[a]-anthracene; 2-azabenz[a]anthracene; 1-azachrysene; 2-azachrysene; 4-azachrysene; 2-azapyrene, and 7,8 benzoquinoline in their neutral and cation forms were investigated. The spectra of these species isolated in an argon matrix have been measured. Band frequencies and intensities were tabulated and these data compared with spectra computed using density functional theory at the B3LYP level. The overall agreement between experiment and theory is quite good, in keeping with earlier results on homonuclear polycyclic aromatic hydrocarbons. The differences between the spectral properties of nitrogen bearing aromatics and non-substituted, neutral polycyclic aromatic hydrocarbons will be discussed.

Pyrolysis of humic and fulvic acids

USGS Publications Warehouse

Wershaw, R. L.; Bohner, G.E.

1969-01-01

Pyrolysis of humic and fulvic acids isolated from a North Carolina soil yields a variety of aromatic, heterocyclic and straight chain organ compounds. The pyrolysis products identified by gas chromatography and mass spectrometry indicate that humic and fulvic acids have aromatic and polysaccharide structures in their molecules. ?? 1969.

Lignin model compounds as bio-based reactive diluents for liquid molding resins.

PubMed

Stanzione, Joseph F; Sadler, Joshua M; La Scala, John J; Wool, Richard P

2012-07-01

Lignin is a copious paper and pulping waste product that has the potential to yield valuable, low molecular weight, single aromatic chemicals when strategically depolymerized. The single aromatic lignin model compounds, vanillin, guaiacol, and eugenol, were methacrylated by esterification with methacrylic anhydride and a catalytic amount of 4-dimethylaminopyridine. Methacrylated guaiacol (MG) and methacrylated eugenol (ME) exhibited low viscosities at room temperature (MG: 17 cP and ME: 28 cP). When used as reactive diluents in vinyl ester resins, they produced resin viscosities higher than that of vinyl ester-styrene blends. The relative volatilities of MG (1.05 wt% loss in 18 h) and ME (0.96 wt% loss in 18 h) measured by means of thermogravimetric analysis (TGA) were considerably lower than that of styrene (93.7 wt% loss in 3 h) indicating the potential of these chemicals to be environmentally friendly reactive diluents. Bulk polymerization of MG and ME generated homopolymers with glass transition temperatures (T(g)s) of 92 and 103 °C, respectively. Blends of a standard vinyl ester resin with MG and ME (50 wt % reactive diluent) produced thermosets with T(g)s of 127 and 153 °C, respectively, which are comparable to vinyl ester-styrene resins, thus demonstrating the ability of MG and ME to completely replace styrene as reactive diluents in liquid molding resins without sacrificing cured-resin thermal performance. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Construction of PAH-degrading mixed microbial consortia by induced selection in soil.

PubMed

Zafra, German; Absalón, Ángel E; Anducho-Reyes, Miguel Ángel; Fernandez, Francisco J; Cortés-Espinosa, Diana V

2017-04-01

Bioremediation of polycyclic aromatic hydrocarbons (PAHs)-contaminated soils through the biostimulation and bioaugmentation processes can be a strategy for the clean-up of oil spills and environmental accidents. In this work, an induced microbial selection method using PAH-polluted soils was successfully used to construct two microbial consortia exhibiting high degradation levels of low and high molecular weight PAHs. Six fungal and seven bacterial native strains were used to construct mixed consortia with the ability to tolerate high amounts of phenanthrene (Phe), pyrene (Pyr) and benzo(a)pyrene (BaP) and utilize these compounds as a sole carbon source. In addition, we used two engineered PAH-degrading fungal strains producing heterologous ligninolytic enzymes. After a previous selection using microbial antagonism tests, the selection was performed in microcosm systems and monitored using PCR-DGGE, CO 2 evolution and PAH quantitation. The resulting consortia (i.e., C1 and C2) were able to degrade up to 92% of Phe, 64% of Pyr and 65% of BaP out of 1000 mg kg -1 of a mixture of Phe, Pyr and BaP (1:1:1) after a two-week incubation. The results indicate that constructed microbial consortia have high potential for soil bioremediation by bioaugmentation and biostimulation and may be effective for the treatment of sites polluted with PAHs due to their elevated tolerance to aromatic compounds, their capacity to utilize them as energy source. Copyright © 2016 Elsevier Ltd. All rights reserved.

Effect of pretreating of host oil on coprocessing

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hajdu, P.E.; Tierney, J.W.; Wender, I.

1995-12-31

The principal objective of this research was to determine if coprocessing performance (i.e., coal conversion and oil yield) could be significantly improved by pretreating the heavy resid prior to reacting it with coal. For this purpose, two petroleum vacuum resids (1000{degrees}F+), one from the Amoco Co. and another from the Citgo Co., were used as such and after they had been pretreated by catalytic hydrogenation and hydrocracking reactions. The pretreatments were aimed at improving the host oil by; (1) converting any aromatic structures in the petroleum to hydroaromatic compounds capable of donating hydrogen, (2) cracking the heavy oil to lowermore » molecular weight material that might serve as a better solvent, (3) reducing the coking propensity of the heavy oil through the hydrogenation of polynuclear aromatic compounds, and (4) removing metals and heteroatoms that might poison a coprocessing catalyst. Highly dispersed catalysts, including fine particle Fe- and Mo-based, and dicobalt octacarbonyl, Co{sub 2}(CO){sub 8}, were used in this study. The untreated and pretreated resids were extensively characterized in order to determine chemical changes brought about by the pretreatments. The modified heavy oils were then coprocessed with an Illinois No. 6 coal as well as with a Wyodak coal, and compared to coprocessing with untreated resids under the same hydroliquefaction conditions. The amount of oil derived from coal was estimated by measuring the level of phenolic oxygen (derived mainly from coal) present in the oil products. Results are presented and discussed.« less

Fog chemistry in the Texas-Louisiana Gulf Coast corridor

NASA Astrophysics Data System (ADS)

Raja, Suresh; Raghunathan, Ravikrishna; Yu, Xiao-Ying; Lee, Taehyoung; Chen, Jing; Kommalapati, Raghava R.; Murugesan, Karthik; Shen, Xinhua; Qingzhong, Yuan; Valsaraj, Kalliat T.; Collett, Jeffrey L.

Fog samples were collected in two population centers of the US Gulf Coast (Houston, Texas and Baton Rouge, Louisiana) using Caltech active strand cloud collectors. A total of 32 fogwater samples were collected in Baton Rouge (November 2004-February 2005) and Houston (February 2006). These samples were analyzed for pH, total and dissolved organic carbon, major inorganic ions, and a variety of organic compounds including organic acids, aromatics, carbonyls, and linear alkanes. Fogs in both environments were of moderate density, with typical fog liquid water contents <100 mg m -3. Fog samples collected in Houston reflect a clear influence of marine and anthropogenic inputs, while Baton Rouge samples also reflect agricultural inputs. The volume-weighted mean fog pH was somewhat more acidic (˜4.3) in Houston than in Baton Rouge (˜5.0). A wide pH range was observed in fog at both locations. Houston fog had higher concentrations of Cl -, NO 3-, Na +, Mg 2+, and Ca 2+. Sulfate to nitrate ratios were high in fogs at both locations, typical of many clouds in the eastern US. Total organic carbon concentrations were much higher in Houston fogs than in Baton Rouge fogs. Efforts to speciate dissolved organic carbon (DOC) reveal large contributions from organic acids and carbonyls, with smaller contributions from other organic compound families including aromatics, alkanes, amides, and alcohols. Approximately 40% of the fog DOC was unspeciated in samples from both study locations.

Comprehensive comparison of the chemical and structural characterization of landfill leachate and leonardite humic fractions.

PubMed

Tahiri, Abdelghani; Richel, Aurore; Destain, Jacqueline; Druart, Philippe; Thonart, Philippe; Ongena, Marc

2016-03-01

Humic substances (HS) are complex and heterogeneous mixtures of organic compounds that occur everywhere in the environment. They represent most of the dissolved organic matter in soils, sediments (fossil), water, and landfills. The exact structure of HS macromolecules has not yet been determined because of their complexity and heterogeneity. Various descriptions of HS are used depending on specific environments of origin and research interests. In order to improve the understanding of the structure of HS extracted from landfill leachate (LHS) and commercial HS from leonardite (HHS), this study sought to compare the composition and characterization of the structure of LHS and HHS using elemental composition, chromatographic (high-performance liquid chromatography (HPLC)), and spectroscopic techniques (UV-vis, FTIR, NMR, and MALDI-TOF). The results showed that LHS molecules have a lower molecular weight and less aromatic structure than HHS molecules. The characteristics of functional groups of both LHS and HHS, however, were basically similar, but there was some differences in absorbance intensity. There were also less aliphatic and acidic functional groups and more aromatic and polyphenolic compounds in the humic acid (HA) fraction than in the fulvic acid (FA) and other molecules (OM) fractions of both origins. The differences between LHS and HHS might be due to the time course of humification. Combining the results obtained from these analytical techniques cold improve our understanding of the structure of HS of different origins and thus enhance their potential use.

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 accounted for only 20% of the reaction, and for one NOM extract (Pony Lake fulvic acid) it accounted for <10%. This shows that for natural organic matter samples, oxidation (ET) is far more important than bromine incorporation (EAS). Copyright © 2015 Elsevier Ltd. All rights reserved.

Base-catalyzed efficient tandem [3 + 3] and [3 + 2 + 1] annulation-aerobic oxidative benzannulations.

PubMed

Diallo, Aboubacar; Zhao, Yu-Long; Wang, He; Li, Sha-Sha; Ren, Chuan-Qing; Liu, Qun

2012-11-16

An efficient synthesis of substituted benzenes via a base-catalyzed [3 + 3] aerobic oxidative aromatization of α,β-unsaturated carbonyl compounds with dimethyl glutaconate was reported. All the reactions were carried out under mild, metal-free conditions to afford the products in high to excellent yields with molecular oxygen as the sole oxidant and water as the sole byproduct. Furthermore, a more convenient tandem [3 + 2 + 1] aerobic oxidative aromatization reaction was developed through the in situ generation of the α,β-unsaturated carbonyl compounds from aldehydes and ketones.

Characterization and distribution of polycyclic aromatic hydrocarbon contaminations in surface sediment and water from Gao-ping River, Taiwan.

PubMed

Doong, Ruey-An; Lin, Yu-Tin

2004-04-01

The concentrations of 16 polycyclic aromatic hydrocarbons (PAHs) in water and sediment samples collected from 12 locations in Gao-ping River, Taiwan were analyzed. Molecular ratios and principal component analysis (PCA) were used to characterize the possible pollution sources. Concentrations of total 16 PAHs (SigmaPAHs) in water samples ranged from below method detection limits (

Organic compounds leached from fast pyrolysis mallee leaf and bark biochars.

PubMed

Lievens, Caroline; Mourant, Daniel; Gunawan, Richard; Hu, Xun; Wang, Yi

2015-11-01

Characterization of organic compounds leached from biochars is essential in assessing the possible toxicity of the biochar to the soils' biota. In this study the nature of the leached organic compounds from Mallee biochars, produced from pyrolysis of Mallee leaf and bark in a fluidised-bed pyrolyser at 400 and 580°C was investigated. Light bio-oil compounds and aromatic organic compounds were investigated. The 'bio-oil like' light compounds from leaf and bark biochars 'surfaces were obtained after leaching the chars with a solvent, suitable to dissolve the respective bio-oils. GC/MS was implemented to investigate the leachates. Phenolics, which are potentially harmful toxins, were detected and their concentration shown to be dependent on the char's origin and the char production temperature. Further, to simulate biochars amendment to soils, the chars were leached with water. The water-leached aromatic compounds from leaf and bark biochars were characterized using UV-fluorescence spectroscopy. Those results suggested that biochars contain leachable compounds of which the nature and amount is dependent on the biomass feedstock, pyrolysis temperature and leaching time. Copyright © 2014 Elsevier Ltd. All rights reserved.

Aromatic Borozene

PubMed Central

2009-01-01

Based on our comprehensive theoretical investigation and known experimental results for small boron clusters, we predict the existence of a novel aromatic inorganic molecule, B12H6. This molecule, which we refer to as borozene, has remarkably similar properties to the well-known benzene. Borozene is planar, possesses a large first excitation energy, D3hsymmetry, and more importantly is aromatic. Furthermore, the calculated anisotropy of the magnetic susceptibility of borozene is three times larger in absolute value than for benzene. Finally, we show that borozene molecules may be fused together to give larger aromatic compounds with even larger anisotropic susceptibilities. PMID:20596438

Biodegradation of high-molecular-weight polycyclic aromatic hydrocarbons under anaerobic conditions: Overview of studies, proposed pathways and future perspectives.

PubMed

Nzila, Alexis

2018-05-07

The biodegradation of low- and high-molecular-weight polycyclic aromatic hydrocarbons (PAHs) (LWM-PAHs and HMW-PAHs, respectively) has been studied extensively under aerobic conditions. Molecular O 2 plays 2 critical roles in this biodegradation process. O 2 activates the aromatic rings through hydroxylation prior to ring opening and serves as a terminal electron acceptor (TEA). However, several microorganisms have devised ways of activating aromatic rings, leading to ring opening (and thus biodegradation) when TEAs other than O 2 are used (under anoxic conditions). These microorganisms belong to the sulfate-, nitrate-, and metal-ion-reducing bacteria and the methanogens. Although the anaerobic biodegradation of monocyclic aromatic hydrocarbons and LWM-PAH naphthalene have been studied, little information is available about the biodegradation of HMW-PAHs. This manuscript reviews studies of the anaerobic biodegradation of HMW-PAHs and identifies gaps that limit both our understanding and the efficiency of this biodegradation process. Strategies that can be employed to overcome these limitations are also discussed. Copyright © 2018 Elsevier Ltd. All rights reserved.

Three-component, one-pot synthesis of anthranilamide Schiff bases bearing 4-aminoquinoline moiety as Mycobacterium tuberculosis gyrase inhibitors.

PubMed

Salve, Preeti S; Alegaon, Shankar G; Sriram, Dharmarajan

2017-04-15

An efficient three-component, one-pot protocol is described for the synthesis of biologically interesting 2-(benzylideneamino)-N-(7-chloroquinolin-4-yl)benzohydrazide derivatives from isatoic anhydride, 7-chloro-4-hydrazinylquinoline and aromatic and/or hetero aromatic aldehydes under catalyst free condensation by using water as reaction media. All synthesized compounds were evaluated for their antimycobacterial activity against Mycobacterium tuberculosis (MTB) and cytotoxicity activity against normal VERO cell lines. The synthesized compounds exhibited minimum inhibitory concentration (MIC) ranging from 0.78 to 25μM. Among the tested compounds 4c, 4o, 4r, and 4u exhibited promising inhibitory activity (MIC=3.12μM). Compounds 4h and 4i stand out, showing MIC values of 0.78 and 1.56μM respectively. Both compounds were further screened for their Mycobacterium tuberculosis DNA gyrase inhibitory assay which suggested that these compounds have a great potential for further optimization and development as antitubercular agents. Copyright © 2017 Elsevier Ltd. All rights reserved.

Gas Chromatography-Mass Spectrometry-Olfactometry To Control the Aroma Fingerprint of Extra Virgin Olive Oil from Three Tunisian Cultivars at Three Harvest Times.

PubMed

Ben Brahim, Samia; Amanpour, Asghar; Chtourou, Fatma; Kelebek, Hasim; Selli, Serkan; Bouaziz, Mohamed

2018-03-21

Gas chromatography-mass spectrometry-olfactometry was used for the analysis of volatile compounds and key odorants of three less studied Tunisian olive oil cultivars for the first time. A total of 42 aroma compounds were identified and quantified in extra virgin olive oils. The present study revealed that the most dominant volatiles in olive oil samples qualitatively and quantitatively were aldehydes and alcohols, followed by terpenes and esters. Indeed, chemometric analysis has shown a correlation between chemical compounds and sensory properties. The determination of aroma-active compounds of olive oil samples was carried out using aroma extract dilution analysis. A total of 15 aroma-active compounds were detected in the aromatic extract of extra virgin olive oil, of which 14 were identified. On the basis of the flavor dilution (FD) factor, the most potent aromatic active compound was hexanal (FD = 512) in Fakhari olive oil, (FD = 256) in Touffehi oils, and (FD = 128) in Jemri olive oil.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ma, W.; Kleunen, A. van; Immerzeel, J.

The purpose of this study was to assess the suitability of applying equilibrium partitioning (EqP) theory to predict the bioaccumulation of polycyclic aromatic hydrocarbons (PAHs) by earthworms when these are exposed to contaminated soils in the field. Studies carried out in situ in various contaminated floodplain sites showed the presence of linear relationships with intercept zero between the lipid-normalized concentration of different PAHs in the earthworm, Lumbricus rubellus and the organic-matter-normalized concentration of the compounds in soil. The demonstration of such an isometric relationship is in agreement with the prediction of EqP theory that the biota-soil accumulation factor (BSAF) shouldmore » be independent of the octanol/water partition coefficient, log K{sub ow}. The average BSAF of PAH compounds in the sampled 20-cm top layer of soil was 0.10. The present study also investigated the route of uptake of PAHs for earthworms in soil. The bioconcentration factor of low-molecular-weight PAHs, such as phenanthrene, fluoranthene, and pyrene, was derived from bioconcentration kinetic modeling of water-only experiments and found to be of the same order of magnitude as the bioaccumulation factor in the field when the latter was normalized to calculated concentrations in soil pore water. The results indicated that the exposure of earthworms to PAHs in soil is mediated through direct contact of the worms with the dissolved interstitial soil-water phase, further supporting the applicability of EqP theory to PAHs. The experimental data on the biotransformation of PAHs suggest that earthworms possess some capacity of metabolization, although this does not seem to be a major factor in the total elimination of these compounds. Even though the EqP approach was found to be applicable to low-molecular-weight PAHs with respect to the prediction of bioaccumulation by earthworms in the field, the results were less conclusive for high-molecular-weight compounds, such as benzo[a]pyrene.« less

APPLICATION OF FATE AND TRANSPORT MODELING TO THE REMEDIAL DECISION MAKING PROCESS – INTRODUCTION TO WORKSHOP

EPA Science Inventory

The conventional site conceptual model for Brownfield sites considers that the extent of plumes of aromatic petroleum hydrocarbons (such as the BTEX compounds) in ground water are limited by natural biodegradation of the aromatic hydrocarbons by bacteria that use oxygen, nitrate ...

SOLAR RADIATION DOSE AND PHOTOTOXICITY OF POLYCYCLIC AROMATIC HYDROCARBONS: A CASE STUDY

EPA Science Inventory

The toxicity of polycyclic aromatic hydrocarbons increases by as much as three orders of magnitude in the presence of solar radiation. The risk of this photoactive toxicity is thus based on both tissue concentrations of potentially photo activated compounds and the levels of subs...

Correlations and adsorption mechanisms of aromatic compounds on biochars produced from various biomass at 700 °C.

PubMed

Yang, Kun; Jiang, Yuan; Yang, Jingjing; Lin, Daohui

2018-02-01

Knowledge of adsorption behavior of organic contaminants on high heat temperature treated biochars is essential for application of biochars as adsorbents in wastewater treatment and soil remediation. In this study, isotherms of 25 aromatic compounds adsorption on biochars pyrolyzed at 700 °C from biomass including wood chips, rice straw, bamboo chips, cellulose, lignin and chitin were investigated to establish correlations between adsorption behavior and physicochemical properties of biochars. Isotherms were well fitted by Polanyi theory-based Dubinin-Ashtakhov (DA) model with three parameters, i.e., adsorption capacity (Q 0 ) and adsorption affinity (E and b). Besides the negative correlation of Q 0 with molecular maximum cross-sectional areas (σ) of organic compounds, positive correlations of Q 0 with total pore volume (V total ) and average diameter of micropore (D) of biochars were observed, indicating that adsorption by biochars is captured by the pore-filling mechanism with molecular sieving effect in biochar pores. Linear solvation energy relationships (LSERs) of adsorption affinity (E) with solvatochromic parameters of organic compounds (i. e., α m and π ∗ ) were established, suggesting that hydrophobic effect, π-π interaction and hydrogen-bonding interaction are the main forces responsible for adsorption. The regression coefficient (π 1 ) and intercept (C) of obtained LSERs are correlated with biochar H/C and R micro , respectively, implying that biochars with higher aromaticity and more micropores have stronger π-π bonding potential and hydrophobic effect potential with aromatic molecule, respectively. However, hydrogen-bonding potential of biochars for organic molecules is not changed significantly with properties of biochars. A negative correlation of b with biochar H/C is also obtained. These correlations could be used to predict the adsorption behavior of organic compounds on high heat temperature treated biochars from various biomass for the application of biochars as sorbents and for the estimating of environmental risks of organic compounds in the present of biochars. Copyright © 2017 Elsevier Ltd. All rights reserved.

The Fate of Crude Oil during Photooxidation under Natural Sunlight

NASA Astrophysics Data System (ADS)

Wang, Q.; Evans, M.; Bacosa, H. P.; Hu, X.; Liu, Z.

2016-02-01

Photooxidation plays an important role in removing spilled crude oil, particularly the aromatic fraction, in surface seawater. Even though much research has been done regarding the changes of different oil fractions by photooxidation, including saturate, aromatic, resin and asphaltene (SARA), we know little about how specific aromatic compounds change in the SARA fractions during photooxidation. In this study, we amended 13C-labled phenanthrene in slightly weathered Louisiana light sweet crude, and followed the fates of 13C values of the SARA fractions during a 44-d incubation experiment under the natural sunlight in south Texas. Our results showed that the aromatic fraction of the crude decreased from 25.4% at time zero to 13.5% at the 44th d, while the resin increased from 12.2% to 16.5% and asphaltene from 2.4% to 13.3%, respectively. This result indicates the aromatic was transformed mostly into asphaltene by photooxidation, and most of the changes took place within the first 10 d. In contrast, no significant difference was observed in the SARA fractions in the dark controls. Analyses of 13C values and phenanthrene concentrations in the SARA fractions are currently on going and will be presented. Results from this experiment provide insights into changes of specific aromatic compounds within oil fractions by photochemical oxidation during oil weathering in the ocean.

A Naphtho- p-quinodimethane Exhibiting Baird’s (Anti)Aromaticity, Broken Symmetry, and Attractive Photoluminescence

DOE PAGES

Shokri, Siamak; Li, Jingbai; Manna, Manoj K.; ...

2017-08-24

In this paper, we report a novel reductive desulfurization reaction involving π-acidic naphthalene diimides 1 (NDI) using thionating agents such as Lawesson’s reagent. Along with the expected thionated NDI derivatives 2-6, new heterocyclic naphtho-p-quinodimethane compounds 7 depicting broken/reduced symmetry were successfully isolated and fully characterized. Empirical studies and theoretical modeling suggest that was formed via a six-membered ring oxathiaphosphenine intermediate rather than the usual four-membered ring oxathiaphosphetane of 2-6. Aside from the reduced symmetry in 7 as confirmed by single-crystal XRD analysis, we established that the ground state UV-vis absorption of 7 is red-shifted in comparison to the parent NDImore » 1. This result was expected in the case of thionated polycyclic diimides. However, unusual low energy transitions originate from Baird 4nπ aromaticity of compounds 7 in lieu of the intrinsic Huckel (4n + 2)π aromaticity as encountered in NDI 1. Moreover, complementary theoretical modeling results also corroborate this change in aromaticity of 7. Consequently, photophysical investigations show that, compared to parent NDI 1, 7 can easily access and emit from its T 1 state with a phosphorescence 3(7a)* lifetime of τ P = 395 μs at 77 K indicative of the formation of the corresponding “aromatic triplet” species according to the Baird’s rule of aromaticity.« less

Oxidation of Naphthenoaromatic and Methyl-Substituted Aromatic Compounds by Naphthalene 1,2-Dioxygenase

PubMed Central

Selifonov, S. A.; Grifoll, M.; Eaton, R. W.; Chapman, P. J.

1996-01-01

Oxidation of acenaphthene, acenaphthylene, and fluorene was examined with recombinant strain Pseudomonas aeruginosa PAO1(pRE695) expressing naphthalene dioxygenase genes cloned from plasmid NAH7. Acenaphthene underwent monooxygenation to 1-acenaphthenol with subsequent conversion to 1-acenaphthenone and cis- and trans-acenaphthene-1,2-diols, while acenaphthylene was dioxygenated to give cis-acenaphthene-1,2-diol. Nonspecific dehydrogenase activities present in the host strain led to the conversion of both of the acenaphthene-1,2-diols to 1,2-acenaphthoquinone. The latter was oxidized spontaneously to naphthalene-1,8-dicarboxylic acid. No aromatic ring dioxygenation products were detected from acenaphthene and acenaphthylene. Mixed monooxygenase and dioxygenase actions of naphthalene dioxygenase on fluorene yielded products of benzylic 9-monooxygenation, aromatic ring dioxygenation, or both. The action of naphthalene dioxygenase on a variety of methyl-substituted aromatic compounds, including 1,2,4-trimethylbenzene and isomers of dimethylnaphthalene, resulted in the formation of benzylic alcohols, i.e., methyl group monooxygenation products, which were subsequently converted to the corresponding carboxylic acids by dehydrogenase(s) in the host strain. Benzylic monooxygenation of methyl groups was strongly predominant over aromatic ring dioxygenation and essentially nonspecific with respect to the substitution pattern of the aromatic substrates. In addition to monooxygenating benzylic methyl and methylene groups, naphthalene dioxygenase behaved as a sulfoxygenase, catalyzing monooxygenation of the sulfur heteroatom of 3-methylbenzothiophene. PMID:16535238

Method for producing heat-resistant semi-inorganic compounds

NASA Technical Reports Server (NTRS)

Yajima, S.; Okamura, K.; Shishido, T.; Hasegawa, Y.

1983-01-01

The method for producing a heat resistant, semi-inorganic compound is discussed. Five examples in which various alcohols, phenols, and aromatic carbonic acids are used to test heat resistance and solubility are provided.

Separation and characterization of gall bladder bile metabolites from speckled trout, Salvelinus fontinalis, exposed to individual polycyclic aromatic compounds.

PubMed

Leonard, J D; Hellou, J

2001-03-01

Speckled trout, Salvelinus fontinalis, were orally exposed to individual polycyclic aromatic compounds (PACs) represented by benzo[a]pyrene, carbazole, chrysene, dibenzofuran, dibenzothiophene, fluorene, phenanthrene, and pyrene. Fish were sacrificed 7 d after exposure and the gall bladder removed for bile analysis. High pressure liquid chromatography (HPLC) with fluorescence (F) and ultraviolet (UV) detection was used to determine the presence of PAC derivatives in the bile without pretreatment. Glucuronide conjugates were predominant in all exposures with variable amounts (0-53%) of phenols and starting material. Identification of compounds was confirmed by selective extraction of less polar nonconjugated PACs and enzymatic hydrolysis of water-soluble material. This was followed by HPLC and/or gas chromatography-mass spectrometry (GCMS) characterization of the produced phenols. Total metabolite levels varied widely among compounds.

Effect of iodide on transformation of phenolic compounds by nonradical activation of peroxydisulfate in the presence of carbon nanotube: Kinetics, impacting factors, and formation of iodinated aromatic products.

PubMed

Guan, Chaoting; Jiang, Jin; Pang, Suyan; Luo, Congwei; Yang, Yi; Ma, Jun; Yu, Jing; Zhao, Xi

2018-06-04

Our recent study has demonstrated that iodide (I - ) can be easily and almost entirely oxidized to hypoiodous acid (HOI) but not to iodate by nonradical activation of peroxydisulfate (PDS) in the presence of a commercial carbon nanotube (CNT). In this work, the oxidation kinetics of phenolic compounds by the PDS/CNT system in the presence of I - were examined and potential formation of iodinated aromatic products was explored. Experimental results suggested that I - enhanced the transformation of six selected substituted phenols, primarily attributed to the generation of HOI that was considerably reactive toward these phenolic compounds. More significant enhancement was obtained at higher I - concentrations or lower pH values, while the change of PDS or CNT dosages exhibited a slight impact on the enhancing effect of I - . Product analyses with liquid chromatography tandem mass spectrometry clearly revealed the production of iodinated aromatic products when p-hydroxybenzoic acid (p-HBA, a model phenol) was treated by the PDS/CNT/I - system in both synthetic and real waters. Their formation pathways probably involved the substitution of HOI on aromatic ring of p-HBA, as well as the generation of iodinated p-HBA phenoxyl radicals and subsequent coupling of these radicals. Given the considerable toxicity and harmful effects of these iodinated aromatic products, particular attention should be paid when the novel PDS/CNT oxidation technology is applied for treatment of phenolic contaminants in iodide-containing waters. Copyright © 2018 Elsevier Ltd. All rights reserved.

Aromatic aldehydes at the active site of aldehyde oxidoreductase from Desulfovibrio gigas: reactivity and molecular details of the enzyme-substrate and enzyme-product interaction.

PubMed

Correia, Hugo D; Marangon, Jacopo; Brondino, Carlos D; Moura, Jose J G; Romão, Maria J; González, Pablo J; Santos-Silva, Teresa

2015-03-01

Desulfovibrio gigas aldehyde oxidoreductase (DgAOR) is a mononuclear molybdenum-containing enzyme from the xanthine oxidase (XO) family, a group of enzymes capable of catalyzing the oxidative hydroxylation of aldehydes and heterocyclic compounds. The kinetic studies reported in this work showed that DgAOR catalyzes the oxidative hydroxylation of aromatic aldehydes, but not heterocyclic compounds. NMR spectroscopy studies using (13)C-labeled benzaldehyde confirmed that DgAOR catalyzes the conversion of aldehydes to the respective carboxylic acids. Steady-state kinetics in solution showed that high concentrations of the aromatic aldehydes produce substrate inhibition and in the case of 3-phenyl propionaldehyde a suicide substrate behavior. Hydroxyl-substituted aromatic aldehydes present none of these behaviors but the kinetic parameters are largely affected by the position of the OH group. High-resolution crystallographic structures obtained from single crystals of active-DgAOR soaked with benzaldehyde showed that the side chains of Phe425 and Tyr535 are important for the stabilization of the substrate in the active site. On the other hand, the X-ray data of DgAOR soaked with trans-cinnamaldehyde showed a cinnamic acid molecule in the substrate channel. The X-ray data of DgAOR soaked with 3-phenyl propionaldehyde showed clearly how high substrate concentrations inactivate the enzyme by binding covalently at the surface of the enzyme and blocking the substrate channel. The different reactivity of DgAOR versus aldehyde oxidase and XO towards aromatic aldehydes and N-heterocyclic compounds is explained on the basis of the present kinetic and structural data.

Toxicity of oil sands acid-extractable organic fractions to freshwater fish: Pimephales promelas (fathead minnow) and Oryzias latipes (Japanese medaka).

PubMed

Bauer, Anthony E; Frank, Richard A; Headley, John V; Peru, Kerry M; Farwell, Andrea J; Dixon, D George

2017-03-01

The Alberta oil sands are one of the largest global petroleum deposits and, due to non-release practices for oil sands process-affected waters, produced tailings are stored in large ponds. The acid extractable organic (AEO) compounds in oil sands process-affected water are of greatest concern due to their persistence and toxicity to a variety of aquatic biota. The present study evaluated the toxicity of the five AEO fractions to two fish species: Oryzias latipes (Japanese medaka) and Pimephales promelas (fathead minnow). The fractions (F1-F5) were comprised of AEO with increasing mean molecular weight and subsequent increases in cyclicity, aromaticity, degree of oxygenation, and heteroatom content. The lowest molecular weight fraction, F1, displayed the lowest acute toxicity to both fish species. For fathead minnow, F5 displayed the greatest toxic potency, while F2 to F4 displayed intermediate toxicities. For Japanese medaka, F2 and F3 displayed the greatest acute toxicities and F1, F4 and F5 were significantly less potent. Overall, fathead minnow were more acutely sensitive to AEO than Japanese medaka. The present study indicates that AEO toxicity may not be solely driven by a narcotic mode of action, but chemical composition such as aromaticity and heteroatom content and their relation to toxicity suggest other drivers indicative of additional modes of toxic action. Copyright © 2016 Elsevier Ltd. All rights reserved.

Weighing the evidence of ecological risk from PAHs contamination in the estuarine environment of Salina Cruz Bay, México.

PubMed

Salazar-Coria, L; Schifter, I; González-Macías, C

2010-03-01

Results of bulk-phase chemical measurements, toxicological tests combined with bioaccumulation measures in fishes, were used to evaluate the toxicity of the 16 USEPA priority polycyclic aromatic hydrocarbons from the sediment collected from eight stations of the Ventosa Estuarine System, located close to the main center of processing oil in the Mexican Pacific coast. Levels of the sum of polycyclic aromatic hydrocarbons varied from 22 to 6,850 microg kg(-1) dry weight. Based on sediment quality guidelines, the compounds with high environmental priority were acenaphtylene, acenaphtene, and phenanthrene. Acute toxicity tests with Vibrio fischeri and Daphnia magna as well as chronic toxicity with Panagrellus redivivus were performed. The quantification of hepatic ethoxyresorufin O-deethylase activity was used to assess the induction of the mixed function oxygenase system of brown trout. However, because it is often difficult to blend the results from such very different assays into a unified decision about the potential for impacts, a weight-of-evidence (WOE) approach to sediment quality investigations was followed. These assays provided measurement endpoints that could be used to develop an overall evaluation of the potential for environmental impacts from the oil processing operations. WOE provides a valuable tool for assessing the results of environmental investigations because it provides a framework for considering the strengths and weaknesses of environmental measurements, an approach for addressing uncertainty in the measurements, and documentation of the evaluation and its assumptions.

Long-term effects of discharges of produced water the marine environment from petroleum-related activities at Sonda de Campeche, Gulf of México.

PubMed

Schifter, I; González-Macías, C; Salazar-Coria, L; Sánchez-Reyna, G; González-Lozano, C

2015-11-01

Produced water from offshore oil platforms is a major source of oil and related chemicals into the sea. The large volume and high salinity of produced water could pose severe environmental impacts upon inadequate disposal. This study is based on direct field sampling of effluents released into the ocean in the years 2003 and 2013 at the Sonda de Campeche located in the southern part of the Gulf of Mexico. Metals and hydrocarbons were characterized in water, sediments, and fish tissues at the discharge site and compared with those obtained at two reference sites. Chemicals that exceeded risk-based concentrations in the discharge included the metals As, Pb, Cd, and Cr, and a variety of compounds polycyclic aromatic hydrocarbon (PAHs), including naphthalene, fluorenes, and low molecular weight PAHs. The values of low to high molecular weight polycyclic aromatic hydrocarbon (PAHs), and carbon preference index indicate that hydrocarbons in sediments of the discharge zone are originated from the produced water and combustion sources. Fish tissues at the discharge zone and reference site are contaminated with PAHs, dominated by 2- and 3-rings; 4-ring accounted for less than 1% of total PAHs (TPAHs) in 2003, but increased to 7% in 2013. Results suggest that, from 2003 to 2013, discharges of produced water have had a non-negligible impact on ecosystems at a regional level, so the possibility of subtle, cumulative effects from operational discharges should not be ignored.

Quantitative estimation of pesticide-likeness for agrochemical discovery.

PubMed

Avram, Sorin; Funar-Timofei, Simona; Borota, Ana; Chennamaneni, Sridhar Rao; Manchala, Anil Kumar; Muresan, Sorel

2014-12-01

The design of chemical libraries, an early step in agrochemical discovery programs, is frequently addressed by means of qualitative physicochemical and/or topological rule-based methods. The aim of this study is to develop quantitative estimates of herbicide- (QEH), insecticide- (QEI), fungicide- (QEF), and, finally, pesticide-likeness (QEP). In the assessment of these definitions, we relied on the concept of desirability functions. We found a simple function, shared by the three classes of pesticides, parameterized particularly, for six, easy to compute, independent and interpretable, molecular properties: molecular weight, logP, number of hydrogen bond acceptors, number of hydrogen bond donors, number of rotatable bounds and number of aromatic rings. Subsequently, we describe the scoring of each pesticide class by the corresponding quantitative estimate. In a comparative study, we assessed the performance of the scoring functions using extensive datasets of patented pesticides. The hereby-established quantitative assessment has the ability to rank compounds whether they fail well-established pesticide-likeness rules or not, and offer an efficient way to prioritize (class-specific) pesticides. These findings are valuable for the efficient estimation of pesticide-likeness of vast chemical libraries in the field of agrochemical discovery. Graphical AbstractQuantitative models for pesticide-likeness were derived using the concept of desirability functions parameterized for six, easy to compute, independent and interpretable, molecular properties: molecular weight, logP, number of hydrogen bond acceptors, number of hydrogen bond donors, number of rotatable bounds and number of aromatic rings.

Concentrations and co-occurrence correlations of 88 volatile organic compounds (VOCs) in the ambient air of 13 semi-rural to urban locations in the United States

USGS Publications Warehouse

Pankow, J.F.; Luo, W.; Bender, D.A.; Isabelle, L.M.; Hollingsworth, J.S.; Chen, C.; Asher, W.E.; Zogorski, J.S.

2003-01-01

The ambient air concentrations of 88 volatile organic compounds were determined in samples taken at 13 semi-rural to urban locations in Maine, Massachusetts, New Jersey, Pennsylvania, Ohio, Illinois, Louisiana, and California. The sampling periods ranged from 7 to 29 months, yielding a large data set with a total of 23,191 individual air concentration values, some of which were designated "ND" (not detected). For each compound at each sampling site, the air concentrations (ca, ppbV) are reported in terms of means, medians, and means of the detected values. The analytical method utilized adsorption/thermal desorption with air-sampling cartridges. The analytes included numerous halogenated alkanes, halogenated alkenes, ethers, alcohols, nitriles, esters, ketones, aromatics, a disulfide, and a furan. At some sites, the air concentrations of the gasoline-related aromatic compounds and the gasoline additive methyl tert-butyl ether were seasonally dependent, with concentrations that maximized in the winter. For each site studied here, the concentrations of some compounds were highly correlated one with another (e.g., the BTEX group (benzene, toluene, ethylbenzene, and the xylenes). Other aromatic compounds were also all generally correlated with one another, while the concentrations of other compound pairs were not correlated (e.g., benzene was not correlated with CFC-12). The concentrations found for the BTEX group were generally lower than the values that have been previously reported for urbanized and industrialized areas of other nations. ?? 2003 Elsevier Ltd. All rights reserved.

REGULATORY PERSPECTIVE ON MANAGING RISKS AT ...

EPA Pesticide Factsheets

Over 700 sites in the United States have been identified where wood preserving operations have been conducted. The most common types of wood preservatives found at these sites are creosote, pentachlorophenol (PCP), and copper chromated arsenate (CCA). When properly used and disposed of, these preservatives do not impose a significant health risk. However, due to operating procedures (many of which were accepted industry practices at the time), wood treating operations have contributed to soil and groundwater contamination. Primary sources of pollution at these sites are lagoons, waste ponds, drip raacki areas and chemical storage and treatment tanks. To better understand the risks associated with the use of wood preserving compounds, it is important to identify the constituents of concern. Creosote is produced as a distillate from coal tar and hence, is a variable mixture of hundreds of compounds, mostly semivolatile organics (SVOCs). Polynuclear Aromatic Hydrocarbons (PAHs) generally, account for up to 85%, by weight, of the chemical constituents found in undiluted creosote. Genetic toxicity if individual PAHs increase with m,olecular weight. USEPA has determined that 7 PAHs are probable human carcinogens and has set forth order-of-magnitue relative potency factors for these constituents, Pentachlorophenol (PCP0 is another preservative used in wood preserving processes and is prepared by dissolving technical grade PCP in oil to produce a solution that

Aromatic polyimides containing a dimethylsilane-linked dianhydride

NASA Technical Reports Server (NTRS)

St.clair, Anne K. (Inventor); St.clair, Terry L. (Inventor); Pratt, J. Richard (Inventor)

1989-01-01

A high-temperature stable, optically transparent, low dielectric aromatic polyimide is prepared by chemically combining equimolar quantities of an aromatic dianhydride reactant and an aromatic diamine reactant, which are selected so that one reactant contains at least one Si(CH3)2 group in its molecular structure, and the other reactant contains at least one -CF3 group in its molecular structure. The reactants are chemically combined in a solvent medium to form a solution of a high molecular weight polyamic acid, which is then converted to the corresponding polyimide.

Aromatic polyimides containing a dimethylsilane-linked dianhydride

NASA Technical Reports Server (NTRS)

St. Clair, Anne K. (Inventor); St. Clair, Terry L. (Inventor); Pratt, J. Richard (Inventor)

1992-01-01

A high-temperature stable, optically transparent, low dielectric aromatic polyimide is prepared by chemically combining equimolar quantities of an aromatic dianhydride reactant and an aromatic diamine reactant, which are selected so that one reactant contains at least one Si(CH.sub.3).sub.2 group in its molecular structure, and the other reactant contains at least one --CH.sub.3 group in its molecular structure. The reactants are chemically combined in a solvent medium to form a solution of a high molecular weight polyamic acid, which is then converted to the corresponding polyimide.

Influence of solids retention time on membrane fouling: characterization of extracellular polymeric substances and soluble microbial products.

PubMed

Duan, Liang; Tian, Zhiyong; Song, Yonghui; Jiang, Wei; Tian, Yuan; Li, Shan

2015-01-01

The objective of this study was to investigate the influence of solids retention time (SRT) on membrane fouling and the characteristics of biomacromolecules. Four identical laboratory-scale membrane bioreactors (MBRs) were operated with SRTs for 10, 20, 40 and 80 days. The results indicated that membrane fouling occurred faster and more readily under short SRTs. Fouling resistance was the primary source of filtration resistance. The modified fouling index (MFI) results suggested that the more ready fouling at short SRTs could be attributed to higher concentrations of soluble microbial products (SMP). Fourier transform infrared (FTIR) spectra indicated that the SRT had a weak influence on the functional groups of the total extracellular polymeric substances (TEPS) and SMP. However, the MBR under a short SRT had more low-molecular-weight (MW) compounds (<1 kDa) and fewer high-MW compounds (>100 kDa). Aromatic protein and tryptophan protein-like substances were the dominant groups in the TEPS and SMP, respectively.

Deep UV laser-induced fluorescence detection of unlabeled drugs and proteins in microchip electrophoresis.

PubMed

Schulze, Philipp; Ludwig, Martin; Kohler, Frank; Belder, Detlev

2005-03-01

Deep UV fluorescence detection at 266-nm excitation wavelength has been realized for sensitive detection in microchip electrophoresis. For this purpose, an epifluorescence setup was developed enabling the coupling of a deep UV laser into a commercial fluorescence microscope. Deep UV laser excitation utilizing a frequency quadrupled pulsed laser operating at 266 nm shows an impressive performance for native fluorescence detection of various compounds in fused-silica microfluidic devices. Aromatic low molecular weight compounds such as serotonin, propranolol, a diol, and tryptophan could be detected at low-micromolar concentrations. Deep UV fluorescence detection was also successfully employed for the detection of unlabeled basic proteins. For this purpose, fused-silica chips dynamically coated with hydroxypropylmethyl cellulose were employed to suppress analyte adsorption. Utilizing fused-silica chips permanently coated with poly(vinyl alcohol), it was also possible to separate and detect egg white chicken proteins. These data show that deep UV fluorescence detection significantly widens the application range of fluorescence detection in chip-based analysis techniques.

The production of aromatic alcohols in non-Saccharomyces wine yeast is modulated by nutrient availability.

PubMed

González, Beatriz; Vázquez, Jennifer; Morcillo-Parra, M Ángeles; Mas, Albert; Torija, María Jesús; Beltran, Gemma

2018-09-01

Aromatic alcohols (tryptophol, phenylethanol, tyrosol) positively contribute to organoleptic characteristics of wines, and are also described as bioactive compounds and quorum sensing molecules. These alcohols are produced by yeast during alcoholic fermentation via the Erhlich pathway, although in non-Saccharomyces this production has been poorly studied. We studied how different wine yeast species modulate the synthesis patterns of aromatic alcohol production depending on glucose, nitrogen and aromatic amino acid availability. Nitrogen limitation strongly promoted the production of aromatic alcohols in all strains, whereas low glucose generally inhibited it. Increased aromatic amino acid concentrations stimulated the production of aromatic alcohols in all of the strains and conditions tested. Thus, there was a clear association between the nutrient conditions and production of aromatic alcohols in most of the wine yeast species analysed. Additionally, the synthesis pattern of these alcohols has been evaluated for the first time in Torulaspora delbrueckii, Metschnikowia pulcherrima and Starmellera bacillaris. Copyright © 2018 Elsevier Ltd. All rights reserved.

Decoding the Secrets of Carbon Preservation and GHG Flux in Lower-Latitude Peatlands

NASA Astrophysics Data System (ADS)

Richardson, C. J.; Flanagan, N. E.; Wang, H.; Ho, M.; Hodgkins, S. B.; Cooper, W. T.; Chanton, J.; Winton, S.

2017-12-01

The mechanisms regulating peat decomposition and C carbon storage in peatlands are poorly understood, particularly with regard to the importance of the biochemical compounds produced by different plant species and in turn peat quality controls on C storage and GHG flux. To examine the role of carbon quality in C accretion in northern compared to tropical peatlands we completed field and lab studies on bog peats collected in Minnesota, North Carolina, Florida and Peru to answer three fundamental questions; 1) is tropical peat more recalcitrant than northern peat 2) does the addition of aromatic and phenolic C compounds increase towards the tropics 3) do differences in the chemical structure of organic matter explain variances in carbon storage and GHG flux in tropical versus northern peatlands? Our main hypothesize is that high concentrations of phenolics and aromatic C compounds produced in shrub and tree plant communities in peatlands coupled with the fire production of biochar aromatics in peatlands may provide a dual biogeochemical latch mechanism controlling microbial decomposition of peat even under higher temperatures and seasonal drought. By comparing the peat bog soil cores collected from the MN peat bogs, NC Pocosins, FL Everglades and Peru palm swamps we find that the soils in the shrub-dominant Pocosin contain the highest phenolics, which microbial studies indicate have the strongest resistance to microbial decomposition. A chemical comparison of plant driven peat carbon quality along a north to south latitudinal gradient indicates that tropical peatlands have higher aromatic compounds, and enhanced phenolics, especially after light fires, which enhances C storage and affect GHG flux across the latitudinal gradient.

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

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kubo, Takanori, E-mail: kubo-t@yasuda-u.ac.jp; Yanagihara, Kazuyoshi; Division of Genetics, National Cancer Center Research Institute, 5-1-1 Tsukiji, Chuo-ku, Tokyo 104-0045

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, suchmore » 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.« less

Atmospheric pressure solid analysis probe coupled to quadrupole-time of flight mass spectrometry as a tool for screening and semi-quantitative approach of polycyclic aromatic hydrocarbons, nitro-polycyclic aromatic hydrocarbons and oxo-polycyclic aromatic hydrocarbons in complex matrices.

PubMed

Carrizo, Daniel; Domeño, Celia; Nerín, Isabel; Alfaro, Pilar; Nerín, Cristina

2015-01-01

A new screening and semi-quantitative approach has been developed for direct analysis of polycyclic aromatic hydrocarbons (PAHs) and their nitro and oxo derivatives in environmental and biological matrices using atmospheric pressure solid analysis probe (ASAP) quadrupole-time of flight mass spectrometry (Q-TOF-MS). The instrumental parameters were optimized for the analysis of all these compounds, without previous sample treatment, in soil, motor oil, atmospheric particles (ashes) and biological samples such as urine and saliva of smokers and non-smokers. Ion source parameters in the MS were found to be the key parameters, with little variation within PAHs families. The optimized corona current was 4 µA, sample cone voltage 80 V for PAHs, nitro-PAHs and oxo-PAHs, while the desolvation temperatures varied from 300°C to 500°C. The analytical method performance was checked using a certified reference material. Two deuterated compounds were used as internal standards for semi-quantitative purposes together with the pure individual standard for each compound and the corresponding calibration plot. The compounds nitro PAH 9-nitroanthracene and oxo-PAH 1,4-naphthalenedione, were found in saliva and urine in a range below 1 µg/g while the range of PAHs in these samples was below 2 µg/g. Environmental samples provided higher concentration of all pollutants than urine and saliva. Copyright © 2014 Elsevier B.V. All rights reserved.

Anaerobic/aerobic treatment of a petrochemical wastewater from two aromatic transformation processes by fluidized bed reactors.

PubMed

Estrada-Arriaga, Edson B; Ramirez-Camperos, Esperanza; Moeller-Chavez, Gabriela E; García-Sanchez, Liliana

2012-01-01

An integrated fluidized bed reactor (FBR) has been employed as the treatment for petrochemical industry wastewaters with high organic matter and aromatic compounds, under anaerobic and aerobic conditions. The system was operated at hydraulic residence time (HRT) of 2.7 and 2.2 h in the anaerobic and aerobic reactor, respectively. The degree of fluidization in the beds was 30%. This system showed a high performance on the removal of organic matter and aromatic compounds. At different organic loading rates (OLR), the chemical oxygen demand (COD) removal in the anaerobic reactor was close to 85% and removals of the COD up to 94% were obtained in the aerobic reactor. High removals of benzene, toluene, ethylbenzene, xylenes, styrene, 1,2,4-trimethylbenzene, 1,3,5-trimethylbenzene and naphthalene were achieved in this study.

Interactions between manganese oxides and multiple-ringed aromatic compounds

DOE Office of Scientific and Technical Information (OSTI.GOV)

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,more » indicating a polymerization-humification process. Results suggest that electron transfer/organic release from the oxide surface is the rate-limiting step.« less

Interactions between manganese oxides and multiple-ringed aromatic compounds

DOE Office of Scientific and Technical Information (OSTI.GOV)

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,more » indicating a polymerization-humification process. Results suggest that electron transfer/organic release from the oxide surface is the rate-limiting step.« less

Infrared and Raman spectra of N-acetyl- L-amino acid methylamides with aromatic side groups

NASA Astrophysics Data System (ADS)

Matsuura, Hiroatsu; Hasegawa, Kodo; Miyazawa, Tatsuo

Infrared and Raman spectra of N-acetyl- L-phenylalanine methylamide, N-acetyl- L-tyrosine methylamide and N-acetyl- L-tryptophan methylamide, as model compounds of aromatic amino acid residues in proteins, were measured in the solid state and in methanol solutions. Vibrational assignments of the spectra were made by utilizing the deuteration effect and by comparison with the spectra of related compounds which include toluene, p-cresol and 3-methylindole. The amide I, III and IV bands were strong in Raman scattering, but other characteristic amide bands were ill-defined. In the Raman spectra of methanol solutions, only the bands due to the aromatic side group vibrations were markedly observed, but those due to the peptide backbone vibrations were very weak, suggesting the coexistence of various molecular conformations in solution.

Lignin depolymerization by fungal secretomes and a microbial sink

DOE Office of Scientific and Technical Information (OSTI.GOV)

Salvachúa, Davinia; Katahira, Rui; Cleveland, Nicholas S.

In Nature, powerful oxidative enzymes secreted by white rot fungi and some bacteria catalyze lignin depolymerization and some microbes are able to catabolize the resulting aromatic compounds as carbon and energy sources. Taken together, these two processes offer a potential route for microbial valorization of lignin. However, many challenges remain in realizing this concept, including that oxidative enzymes responsible for lignin depolymerization also catalyze polymerization of low molecular weight (LMW) lignin. Here, multiple basidiomycete secretomes were screened for ligninolytic enzyme activities in the presence of a residual lignin solid stream from a corn stover biorefinery, dubbed DMR-EH (Deacetylation, Mechanical Refining,more » and Enzymatic Hydrolysis) lignin. Two selected fungal secretomes, with high levels of laccases and peroxidases, were utilized for DMR-EH lignin depolymerization assays. The secretome from Pleurotus eryngii, which exhibited the highest laccase activity, reduced the lignin average molecular weight by 63% and 75% at pH 7 compared to the Mw of the control treated at the same conditions and the initial DMR-EH lignin, respectively, and was applied in further depolymerization assays as a function of time. As repolymerization was observed after 3 days of incubation, an aromatic-catabolic microbe (Pseudomonas putida KT2440) was incubated with the fungal secretome and DMR-EH lignin. These experiments demonstrated that the presence of the bacterium enhances lignin depolymerization, likely due to bacterial catabolism of LMW lignin, which may partially prevent repolymerization. In addition, proteomics was also applied to the P. eryngii secretome to identify the enzymes present in the fungal cocktail utilized for the depolymerization assays, which highlighted a significant number of glucose/ methanol/choline (GMC) oxidoreductases and laccases. Overall, this study demonstrates that ligninolytic enzymes can be used to partially depolymerize a solid, high lignin content biorefinery stream and that the presence of an aromatic-catabolic bacterium as a “microbial sink” improves the extent of enzymatic lignin depolymerization.« less

Lignin depolymerization by fungal secretomes and a microbial sink

DOE PAGES

Salvachua, Davinia; Katahira, Rui; Cleveland, Nicholas S.; ...

2016-08-25

In Nature, powerful oxidative enzymes secreted by white rot fungi and some bacteria catalyze lignin depolymerization and some microbes are able to catabolize the resulting aromatic compounds as carbon and energy sources. Taken together, these two processes offer a potential route for microbial valorization of lignin. However, many challenges remain in realizing this concept, including that oxidative enzymes responsible for lignin depolymerization also catalyze polymerization of low molecular weight (LMW) lignin. Here, multiple basidiomycete secretomes were screened for ligninolytic enzyme activities in the presence of a residual lignin solid stream from a corn stover biorefinery, dubbed DMR-EH (Deacetylation, Mechanical Refining,more » and Enzymatic Hydrolysis) lignin. Two selected fungal secretomes, with high levels of laccases and peroxidases, were utilized for DMR-EH lignin depolymerization assays. The secretome from Pleurotus eryngii, which exhibited the highest laccase activity, reduced the lignin average molecular weight (M w) by 63% and 75% at pH 7 compared to the M w of the control treated at the same conditions and the initial DMR-EH lignin, respectively, and was applied in further depolymerization assays as a function of time. As repolymerization was observed after 3 days of incubation, an aromatic-catabolic microbe ( Pseudomonas putida KT2440) was incubated with the fungal secretome and DMR-EH lignin. These experiments demonstrated that the presence of the bacterium enhances lignin depolymerization, likely due to bacterial catabolism of LMW lignin, which may partially prevent repolymerization. In addition, proteomics was also applied to the P. eryngii secretome to identify the enzymes present in the fungal cocktail utilized for the depolymerization assays, which highlighted a significant number of glucose/methanol/choline (GMC) oxidoreductases and laccases. Altogether, this study demonstrates that ligninolytic enzymes can be used to partially depolymerize a solid, high lignin content biorefinery stream and that the presence of an aromatic-catabolic bacterium as a 'microbial sink' improves the extent of enzymatic lignin depolymerization.« less

Lignin depolymerization by fungal secretomes and a microbial sink

DOE Office of Scientific and Technical Information (OSTI.GOV)

Salvachua, Davinia; Katahira, Rui; Cleveland, Nicholas S.

In Nature, powerful oxidative enzymes secreted by white rot fungi and some bacteria catalyze lignin depolymerization and some microbes are able to catabolize the resulting aromatic compounds as carbon and energy sources. Taken together, these two processes offer a potential route for microbial valorization of lignin. However, many challenges remain in realizing this concept, including that oxidative enzymes responsible for lignin depolymerization also catalyze polymerization of low molecular weight (LMW) lignin. Here, multiple basidiomycete secretomes were screened for ligninolytic enzyme activities in the presence of a residual lignin solid stream from a corn stover biorefinery, dubbed DMR-EH (Deacetylation, Mechanical Refining,more » and Enzymatic Hydrolysis) lignin. Two selected fungal secretomes, with high levels of laccases and peroxidases, were utilized for DMR-EH lignin depolymerization assays. The secretome from Pleurotus eryngii, which exhibited the highest laccase activity, reduced the lignin average molecular weight (M w) by 63% and 75% at pH 7 compared to the M w of the control treated at the same conditions and the initial DMR-EH lignin, respectively, and was applied in further depolymerization assays as a function of time. As repolymerization was observed after 3 days of incubation, an aromatic-catabolic microbe ( Pseudomonas putida KT2440) was incubated with the fungal secretome and DMR-EH lignin. These experiments demonstrated that the presence of the bacterium enhances lignin depolymerization, likely due to bacterial catabolism of LMW lignin, which may partially prevent repolymerization. In addition, proteomics was also applied to the P. eryngii secretome to identify the enzymes present in the fungal cocktail utilized for the depolymerization assays, which highlighted a significant number of glucose/methanol/choline (GMC) oxidoreductases and laccases. Altogether, this study demonstrates that ligninolytic enzymes can be used to partially depolymerize a solid, high lignin content biorefinery stream and that the presence of an aromatic-catabolic bacterium as a 'microbial sink' improves the extent of enzymatic lignin depolymerization.« less

Monomers for thermosetting and toughening epoxy resins. [glycidyl amine derivatives, propargyl-containing amines, and mutagenic testing of aromatic diamines

NASA Technical Reports Server (NTRS)

Pratt, J. R.

1981-01-01

Eight glycidyl amines were prepared by alkylating the parent amine with epichlorohydrin to form chlorohydrin, followed by cyclization with aqueous NaOH. Three of these compounds contained propargyl groups with postcuring studies. A procedure for quantitatively estimating the epoxy content of these glycidyl amines was employed for purity determination. Two diamond carbonates and several model propargly compounds were prepared. The synthesis of three new diamines, two which contain propargyloxy groups, and another with a sec-butyl group is in progress. These materials are at the dinitro stage ready for the final hydrogenation step. Four aromatic diamines were synthesized for mutagenic testing purposes. One of these compounds rapidly decomposes on exposure to air.

Antioxidant and Anti-Osteoporotic Activities of Aromatic Compounds and Sterols from Hericium erinaceum.

PubMed

Li, Wei; Lee, Sang Hyun; Jang, Hae Dong; Ma, Jin Yeul; Kim, Young Ho

2017-01-11

Hericium erinaceum , commonly called lion's mane mushroom, is a traditional edible mushroom widely used in culinary applications and herbal medicines in East Asian countries. In this study, a new sterol, cerevisterol 6-cinnamate ( 6 ), was isolated from the fruiting bodies of H. erinaceum together with five aromatic compounds 1 - 5 and five sterols 7 - 11 . The chemical structures of these compounds were elucidated using chemical and physical methods and comparison of HRESIMS, ¹D-NMR (¹H, 13 C, and DEPT) and 2D-NMR (COSY, HMQC, HMBC, and NOESY) spectra with previously reported data. The antioxidant and anti-osteoporotic activities of extracts and the isolated compounds 1 - 11 were investigated. All compounds exhibited peroxyl radical-scavenging capacity but only compounds 1 , 3 , and 4 showed potent reducing capacity. Moreover, compounds 1 , 2 , 4 , and 5 showed moderate effects on cellular antioxidant activity and inhibited the receptor activator of nuclear factor κB ligand (RANKL)-induced osteoclastic differentiation. These results suggested that H. erinaceum could be utilized in the development of natural antioxidant and anti-osteoporotic nutraceuticals and functional foods.

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

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gritti, Fabrice; Guiochon, Georges A; Mayfield, Kirsty

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 weightmore » 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.« less

Cloning and heterologous expression of two aryl-aldehyde dehydrogenases from the white-rot basidiomycete Phanerochaete chrysosporium

DOE Office of Scientific and Technical Information (OSTI.GOV)

Nakamura, Tomofumi; Fukuoka Institute of Health and Environmental Sciences, 39 Mukaizano, Dazaifu-shi, Fukuoka 818-0135; Ichinose, Hirofumi

2010-04-09

We identified two aryl-aldehyde dehydrogenase proteins (PcALDH1 and PcALDH2) from the white-rot basidiomycete Phanerochaete chrysosporium. Both PcALDHs were translationally up-regulated in response to exogenous addition of vanillin, one of the key aromatic compounds in the pathway of lignin degradation by basidiomycetes. To clarify the catalytic functions of PcALDHs, we isolated full-length cDNAs encoding these proteins and heterologously expressed the recombinant enzymes using a pET/Escherichia coli system. The open reading frames of both PcALDH1 and PcALDH2 consisted of 1503 nucleotides. The deduced amino acid sequences of both proteins showed high homologies with aryl-aldehyde dehydrogenases from other organisms and contained ten conservedmore » domains of ALDHs. Moreover, a novel glycine-rich motif 'GxGxxxG' was located at the NAD{sup +}-binding site. The recombinant PcALDHs catalyzed dehydrogenation reactions of several aryl-aldehyde compounds, including vanillin, to their corresponding aromatic acids. These results strongly suggested that PcALDHs metabolize aryl-aldehyde compounds generated during fungal degradation of lignin and various aromatic xenobiotics.« less

Concentrations in human blood of petroleum hydrocarbons associated with the BP/Deepwater Horizon oil spill, Gulf of Mexico.

PubMed

Sammarco, Paul W; Kolian, Stephan R; Warby, Richard A F; Bouldin, Jennifer L; Subra, Wilma A; Porter, Scott A

2016-04-01

During/after the BP/Deepwater Horizon oil spill, cleanup workers, fisherpersons, SCUBA divers, and coastal residents were exposed to crude oil and dispersants. These people experienced acute physiological and behavioral symptoms and consulted a physician. They were diagnosed with petroleum hydrocarbon poisoning and had blood analyses analyzed for volatile organic compounds; samples were drawn 5-19 months after the spill had been capped. We examined the petroleum hydrocarbon concentrations in the blood. The aromatic compounds m,p-xylene, toluene, ethylbenzene, benzene, o-xylene, and styrene, and the alkanes hexane, 3-methylpentane, 2-methylpentane, and iso-octane were detected. Concentrations of the first four aromatics were not significantly different from US National Health and Nutritional Examination Survey/US National Institute of Standards and Technology 95th percentiles, indicating high concentrations of contaminants. The other two aromatics and the alkanes yielded equivocal results or significantly low concentrations. The data suggest that single-ring aromatic compounds are more persistent in the blood than alkanes and may be responsible for the observed symptoms. People should avoid exposure to crude oil through avoidance of the affected region, or utilizing hazardous materials suits if involved in cleanup, or wearing hazardous waste operations and emergency response suits if SCUBA diving. Concentrations of alkanes and PAHs in the blood of coastal residents and workers should be monitored through time well after the spill has been controlled.

N,S,O-Heterocycles in Aged Champagne Reserve Wines and Correlation with Free Amino Acid Concentrations.

PubMed

Le Menn, Nicolas; Marchand, Stephanie; de Revel, Gilles; Demarville, Dominique; Laborde, Delphine; Marchal, Richard

2017-03-22

Champagne regulations allow winegrowers to stock still wines to compensate for quality shifts in vintages, mainly due to climate variations. According to their technical requirements and house style, Champagne producers use these stored wines in their blends to enhance complexity. The presence of lees and aging at low pH (2.95-3.15), as in Champagne wines, lead to several modifications in wine composition. These conditions, combined with extended aging, result in the required environment for the Maillard chemical reaction, involving aromatic molecules, including sulfur, oxygen, and nitrogen heterocycles (such as thiazole, furan, and pyrazine derivatives), which may have a sensory impact on wine. Some aromatic heterocycles in 50 monovarietal wines aged from 1 to 27 years provided by Veuve Clicquot Ponsardin Champagne house were determined by the SPME-GC-MS method. The most interesting result highlighted a strong correlation between certain heterocycle concentrations and wine age. The second revealed a correlation between heterocyclic compound and free amino acid concentrations measured in the wines, suggesting that these compounds are potential aromatic precursors when wine is aged on lees and, thus, potential key compounds in the bouquet of aged Champagnes. The principal outcome of these assays was to reveal, for the first time, that aromatic heterocycle concentrations in Champagne base wines are correlated with wine age.

A concentration-dependent multi-term linear free energy relationship for sorption of organic compounds to soils based on the hexadecane dilute-solution reference state.

PubMed

Zhu, Dongqiang; Pignatello, Joseph J

2005-11-15

A LFER of the type in the title is applied to sorption of numerous compounds to polyethylene and three soils for which sorption to natural organic matter (NOM) is presumed dominant. It provides fractional contributions to the Gibbs free energy of sorption corresponding to hydrophobic effects, dipolar/polarizability (D/P) effects in excess of the reference state, and the sum of possible specific forces such as H-bonding and pi-pi electron donor-acceptor (pi-pi EDA) interactions in excess of the reference state. Minimal inputs are the isotherm, the n-hexadecane-water partition coefficient and the Abraham pi parameter representing D/P effects. Sorption of all compounds to polyethylene can be described by considering only hydrophobic effects. Sorption of a calibration set of apolar compounds (aromatic and aliphatic hydrocarbons and chlorinated hydrocarbons) to the natural sorbents is well-described by a combination of hydrophobic and D/P effects. For the apolar set, D/P contributes approximately 15-40% (2-8% for cyclohexane) of sorption free energy. D/P effects increase with the degree of chlorination for aliphatic compounds. For aromatic compounds D/P effects increase with fused ring size but do not vary with degree of chlorination and chlorine substitution pattern. H-bonding contributes substantially to sorption of alcohols, and similarly for 2-nonanol and 2,4-dichlorophenol (33-44%). pi-pi EDA forces contribute to phenanthrene sorption in one case. The effects of concentration, sorbent aromaticity (literature NMR), and sorbent polarity [(O + N)/C] on hydrophobic and D/P contributions for all compounds indicate that (a) molecules fill sites of progressively greater hydrophilic character; (b) the energy penalty for cavity formation in the solid decreases with concentration due to plasticization and greater intermolecular contact; (c) sorbent aromatic content more than sorbent polarity controls D/P interactions. Basing free energy on an inert electrostatic chemical environment afforded by n-hexadecane permits evaluation of direct electrostatic forces in NOM that contribute to sorption.

DEPENDENCY OF POLYCHLORINATED BIPHENYL AND POLYCYCLIC AROMATIC HYDROCARBON BIOACCUMULATION IN MYA ARENARIA ON BOTH WATER COLUMN AND SEDIMENT BED CHEMICAL ACTIVITIES

EPA Science Inventory

The bioaccumulation of polycyclic aromatic hydrocarbons (PAHs) and polychlorinated biphenyls (PCBs) by the filter-feeding soft-shell clam Mya arenaria was evaluated at three sites near Boston (MA, USA) by assessing the chemical activities of those hydrophobic organic compounds (H...

Polybenzimidazoles Via Aromatic Nucleophilic Displacement

NASA Technical Reports Server (NTRS)

Connell, John W.; Hergenrother, Paul M.; Smith, Joseph G.

1994-01-01

Soluble polybenzimidazoles (PBI's) synthesized by nucleophilic displacement reaction of di(hydroxyphenyl)-benzimidazole monomers with activated aromatic difluoride compounds in presence of anhydrous potassium carbonate. These polymers exhibit good thermal, thermo-oxidative, and chemical stability, and high mechanical properties. Using benzimidazole monomers, more economical, and new PBI's processed more easily than commercial PBI, without loss of desirable physical properties.

AROMATIC METABOLISM IN PLANTS. I. A STUDY OF THE PREPHENATE DEHYDROGENASE FROM BEAN PLANTS,

DTIC Science & Technology

achieved in the pH range from 7 to 8. The enzyme is inhibited by sulphydryl complexing compounds. Addition of phenylalanine, tyrosine, or cinnamate ...mung bean (Phaseolus aureus Roxb.). A study was made of the variation in the amount of prephenate dehydrogenase and aromatic amino acid transaminase in

Synthesis of Triarylmethane and Xanthene Dyes Using Electrophilic Aromatic Substitution Reactions

ERIC Educational Resources Information Center

McCullagh, James V.; Daggett, Kelly A.

2007-01-01

The synthesis of dyes has long been a popular topic in organic chemistry laboratory experiments because it allows students to see first hand that reactions learned in class can be used to make compounds with useful applications. In this experiment electrophilic aromatic substitution reactions are used to synthesize several triarylmethane and…

Multiple Cosmic Sources for Meteorite Macromolecules?

PubMed Central

Watson, Jonathan S.; Meredith, William; Love, Gordon D.; Gilmour, Iain; Snape, Colin E.

2015-01-01

Abstract The major organic component in carbonaceous meteorites is an organic macromolecular material. The Murchison macromolecular material comprises aromatic units connected by aliphatic and heteroatom-containing linkages or occluded within the wider structure. The macromolecular material source environment remains elusive. Traditionally, attempts to determine source have strived to identify a single environment. Here, we apply a highly efficient hydrogenolysis method to liberate units from the macromolecular material and use mass spectrometric techniques to determine their chemical structures and individual stable carbon isotope ratios. We confirm that the macromolecular material comprises a labile fraction with small aromatic units enriched in 13C and a refractory fraction made up of large aromatic units depleted in 13C. Our findings suggest that the macromolecular material may be derived from at least two separate environments. Compound-specific carbon isotope trends for aromatic compounds with carbon number may reflect mixing of the two sources. The story of the quantitatively dominant macromolecular material in meteorites appears to be made up of more than one chapter. Key Words: Abiotic organic synthesis—Carbonaceous chondrite—Cosmochemistry—Meteorites. Astrobiology 15, 779–786. PMID:26418568

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

NASA Technical Reports Server (NTRS)

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

2006-01-01

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

[Allergy to cosmetics. I. Fragrances].

PubMed

Kieć-Swierczyńska, Marta; Krecisz, Beata; Swierczyńska-Machura, Dominika

2004-01-01

The authors report current information on allergy to aromatic agents present in cosmetics and products of household chemistry. In the perfume industry, about 3000 aromas are used. Single products may contain from 10 to 300 compounds. The problem of difficulties encountered in the diagnosis of hypersensitivity to odors is addressed. The mixture of 8 such products used in diagnostic screening is able to detect allergy only in about 30% of patients who do not tolerate cosmetics. Changing frequency of allergy to individual aromas is discussed. It has been now observed that cinnamon products are less allergic than chemical compounds present in oak moss. Since the 1990s of the last century, allergy to a synthetic aromatic agent, Lyral is the subject of interest in many research centers involved in studies of contact allergy. Half the cosmetics present in European markets, especially deodorants, after shave cosmetics, hand and body lotions contain this agent. It induces positive reactions in about 10% of patients allergic to aromatic agents. Detection of allergy to Lyral is difficult as it is not included in the set of commercial allergens used to diagnose hypersensitivity to aromatic agents.

Aerobic Heterotrophic Bacterial Populations of Sewage and Activated Sludge

PubMed Central

Prakasam, T. B. S.; Dondero, N. C.

1970-01-01

An activated sludge from a sewage treatment plant and a laboratory activated sludge developed on an artificial waste were compared for their ability to utilize 11 aromatic compounds. There were several significant differences between them. The laboratory sludge contained higher numbers of organisms and metabolized the aromatics to a greater extent. Laboratory activated sludges acclimated to utilization of the aromatics differed from each other in population structure and the pattern of oxygen consumption with aromatic substrates. The oxidative patterns of uncontrolled mixed populations were unreliable for investigating metabolic pathways. Extracts of the various sludges elevated the plate counts of the sludges. PMID:5418946

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

NASA Technical Reports Server (NTRS)

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

1999-01-01

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

Volatile and semivolatile organic compounds in laboratory ...

EPA Pesticide Factsheets

Speciated volatile organic compounds (VOCs) and organic fine particulate matter (PM2.5) mass emission factors were determined from laboratory peat fire experiments. Peat samples originated from two wildlife reserves located near the coast of North Carolina, U.S. Gas and particulate organics were quantified by gas chromatography/mass spectrometry and by high pressure liquid chromatography. Hazardous air pollutants (HAPs) accounted for a large fraction (~60 %) of the speciated VOC emissions from peat burning, including large contributions of acetaldehyde, formaldehyde, benzene, toluene, and chloromethane. Speciated organic PM2.5 mass was dominated by the following compound classes: organic acids, levoglucosan, n-alkanes, and n-alkenes. Emission factors for PM2.5 organic acids including n-alkanoic acids, n-alkenoic acids, n-alkanedioic acids, and aromatic acids were reported for the first time for peat burning, representing the largest fraction of organic carbon (OC) mass (11-12 %) of all speciated compound classes measured in this work. Levoglucosan contributed 2-3 % of the OC mass, while methoxyphenols represented 0.2-0.3 % of the OC mass on a carbon mass basis. Retene was the most abundant particulate phase polycyclic aromatic hydrocarbon. Total HAP VOC and particulate polycyclic aromatic hydrocarbon emissions from a 2008 peat wildfire in North Carolina were estimated, suggesting that peat fires can contribute a large fraction of state-wide HAP emissions. This p

Thirty-three years of 2-acetyl-1-pyrroline, a principal basmati aroma compound in scented rice (Oryza sativa L.): a status review.

PubMed

Wakte, Kantilal; Zanan, Rahul; Hinge, Vidya; Khandagale, Kiran; Nadaf, Altafhusain; Henry, Robert

2017-01-01

Rice is the staple food of around 3 billion people, most of them in Asia which accounts for 90% of global rice consumption. Aromatic rices have been preferred over non-aromatic rice for hundreds of years. They have a premium value in national as well as international market owing to their unique aroma and quality. Many researchers were involved in identifying the compound responsible for the pleasant aroma in aromatic rice in the 20th century. However, due to its unstable nature, 2-acetyl-1-pyrroline (2AP) was discovered very late, in 1982. Buttery and co-workers found 2AP to be the principal compound imparting the pleasant aroma to basmati and other scented rice varieties. Since then, 2AP has been identified in all fragrant rice (Oryza sativa L.) varieties and a wide range of plants, animals, fungi, bacteria and various food products. The present article reviews in detail biochemical and genetic aspects of 2AP in living systems. The site of synthesis, site of storage and stability in plant systems in vivo is of interest. This compound requires more research on stability to facilitate use as a food additive. © 2016 Society of Chemical Industry. © 2016 Society of Chemical Industry.

Occupational exposure to rubber vulcanization products during repair of rubber conveyor belts in a brown coal mine.

PubMed

Gromiec, Jan P; Wesołowski, Wiktor; Brzeźnicki, Sławomir; Wróblewska-Jakubowska, Krystyna; Kucharska, Małgorzata

2002-12-01

Several hundred chemical compounds were found in workroom environments in the rubber industry, but most of the published exposure data relate to the production of tyres; information from the "non-tyre" sections are very limited, if any. This study was carried out to identify chemical substances and measure their air concentrations in the repair shop of a brown coal mine in which damaged rubber conveyor belts were repaired. GC-MS and HPLC analysis of stationary air samples resulted in identification of aliphatic and aromatic hydrocarbons to C12, PAHs, alcohols, phenols, ketones, heterocyclic nitrogen and sulfur compounds. Quantitative evaluation of occupational exposure included determination of organic compound vapours collected on charcoal (GC-MSD), polycyclic aromatic hydrocarbons (HPLC), N-nitrosoamines and other amines (GC-NPD) and DNPH derivatives of aldehydes (HPLC) in the breathing zone of workers representing all job titles. The concentrations of investigated compounds were very low. Carcinogenic substances: N-nitrosoamines, benzene, PAHs were not present in workroom air in concentrations exceeding limits of detection of the analytical methods being applied; concentrations of methylisobutylketone, tetrachloroethylene, naphtha, aromatic hydrocarbons, phthalates and aldehydes were much lower than the respective occupational exposure limit values. The results indicate much lower exposure than that reported in the production of tyres and other fabricated rubber products.

Chronic toxicity of selected polycyclic aromatic hydrocarbons to algae and crustaceans using passive dosing.

PubMed

Bragin, Gail E; Parkerton, Thomas F; Redman, Aaron D; Letinksi, Daniel J; Butler, Josh D; Paumen, Miriam Leon; Sutherland, Cary A; Knarr, Tricia M; Comber, Mike; den Haan, Klaas

2016-12-01

Because of the large number of possible aromatic hydrocarbon structures, predictive toxicity models are needed to support substance hazard and risk assessments. Calibration and evaluation of such models requires toxicity data with well-defined exposures. The present study has applied a passive dosing method to generate reliable chronic effects data for 8 polycyclic aromatic hydrocarbons (PAHs) on the green algae Pseudokirchneriella subcapitata and the crustacean Ceriodaphnia dubia. The observed toxicity of these substances on algal growth rate and neonate production were then compared with available literature toxicity data for these species, as well as target lipid model and chemical activity-based model predictions. The use of passive dosing provided well-controlled exposures that yielded more consistent data sets than attained by past literature studies. Results from the present study, which were designed to exclude the complicating influence of ultraviolet light, were found to be well described by both target lipid model and chemical activity effect models. The present study also found that the lack of chronic effects for high molecular weight PAHs was consistent with the limited chemical activity that could be achieved for these compounds in the aqueous test media. Findings from this analysis highlight that variability in past literature toxicity data for PAHs may be complicated by both poorly controlled exposures and photochemical processes that can modulate both exposure and toxicity. Environ Toxicol Chem 2016;35:2948-2957. © 2016 SETAC. © 2016 SETAC.

Effects of humic substances on the bioconcentration of polycyclic aromatic hydrocarbons: Correlations with spectroscopic and chemical properties of humic substances

USGS Publications Warehouse

Haitzer, M.; Abbt-Braun, G.; Traunspurger, W.; Steinberg, C.E.W.

1999-01-01

The presence of dissolved humic substances (HS, fulvic and humic acids) generally reduces the uptake of hydrophobic organic compounds into aquatic organisms. The extent of this effect depends both on the concentration and on the origin of the HS. The aim of this study was to investigate the role of qualitative differences between HS from different origins. The effects of seven different HS on the bioconcentration of pyrene and benzo[a]pyrene (BaP) in the nematode Caenorhabditis elegans were related to the spectroscopic and chemical properties of the HS. The effect of each humic material on the bioconcentration of pyrene or BaP was quantified as a 'biologically determined' partition coefficient K(DOC). We observed significant linear relationships between K(DOC) and the atomic H/C ratio, the specific absorptivity at 254 nm, the content of aromatic carbons (as determined by 13C nuclear magnetic resonance spectroscopy, the copper-complexing capacity, the content of phenolic OH groups, and the molecular weight of the HS. There was no discernible relationship of K(DOC) with the atomic (N + O)/C ratio, an indicator of the polarity of HS. Taken together, our results show that the variability in the effects of HS from different origins could be related to variations in bulk properties of the HS. Parameters describing the aromaticity of the humic materials seemed to be most useful for estimating effects of HS on the bioconcentration of pyrene and BaP.

Regioselctive Thiocyanation of Aromatic and Heteroaromatic Compounds Using a Novel Bronsted Acidic Ionic Liquid.

PubMed

Rezayati, Sobhan; Sheikholeslami-Farahani, Fatemeh; Hossaini, Zinatossadat; Hajinasiri, Rahimeh; Abad, Saeid Afshari Sharif

2016-01-01

A convenient procedure for the preparation of 1-(1-Propylsulfonic)-3- methylimidazolium thiocyanate as a novel Brønsted acidic ionic liquid thiocyanation agent and highly efficient heterogeneous catalytic is described. This catalyst is used in regioselective thiocyanation of indoles, anilines, pyrroles and their derivatives (aromatic and heteroaromatic organic compounds) in the presence of H2O2 as a mild and oxidant in EtOH:H2O (1:1 v/v). These reactions are performed under mild and simple conditions and give regioselective products in high yields and short reaction time.

Beta-galactosidase catalyzed selective galactosylation of aromatic compounds.

PubMed

Bridiau, Nicolas; Taboubi, Selma; Marzouki, Nejib; Legoy, Marie Dominique; Maugard, Thierry

2006-01-01

A new approach to galacto-oligosaccharides and galacto-conjugates synthesis performed by the beta-galactosidase from Kluyveromyces lactis is reported. The enzymatic galactosylation of eight kinds of adsorbed aromatic primary alcohols, in particular the two drugs guaifenesin and chlorphenesin, gave the corresponding beta-D-galacto-pyranosides in yields ranging between approximately 10% and 96%. For the first time, we have showed that the adsorption of acceptor substrates onto solid supports such as silica gel influences the yield and the selectivity of galacto-conjugates synthesis. In particular, we observed that adsorption of acceptor favored the synthesis of digalactosylated compounds.

Continuous process for conversion of coal

DOEpatents

Knudson, Curtis L.; Willson, Warrack G.; Baker, Gene G.; Sondreal, Everett A.; Farnum, Sylvia A.

1982-01-01

An improved process for converting coal to liquid and gaseous products wherein the liquid products predominate and wherein reactor, tubing, and valve plugging due to carbonate salt formation is reduced by reacting crushed low-rank coal containing about 12 to 30% by weight of water in a solvent at a temperature in the range of about 455.degree. to 500.degree. C., under about 2000 to 5000 psi pressure of a H.sub.2 /CO mixture for a liquid residence time of about 20 to 60 minutes. The solvent is a fraction of liquid product defined on a weight basis as being made up of about 55% of which distills at less than 250.degree. C./lmm, about 20% of which is soluble in THF, and about 25% of which is carbon polymer and indigenous inorganic matter. The solvent is further defined as containing at least about 5 weight % of partially hydrogenated aromatics and/or fully hydrogenated aromatics and little or no alkylated aromatics or higher alkanes.

Measured and Predicted Vapor Liquid Equilibrium of Ethanol-Gasoline Fuels with Insight on the Influence of Azeotrope Interactions on Aromatic Species Enrichment and Particulate Matter Formation in Spark Ignition Engines

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ratcliff, Matthew A; McCormick, Robert L; Burke, Stephen

A relationship has been observed between increasing ethanol content in gasoline and increased particulate matter (PM) emissions from direct injection spark ignition (DISI) vehicles. The fundamental cause of this observation is not well understood. One potential explanation is that increased evaporative cooling as a result of ethanol's high HOV may slow evaporation and prevent sufficient reactant mixing resulting in the combustion of localized fuel rich regions within the cylinder. In addition, it is well known that ethanol when blended in gasoline forms positive azeotropes which can alter the liquid/vapor composition during the vaporization process. In fact, it was shown recentlymore » through a numerical study that these interactions can retain the aromatic species within the liquid phase impeding the in-cylinder mixing of these compounds, which would accentuate PM formation upon combustion. To better understand the role of the azeotrope interactions on the vapor/liquid composition evolution of the fuel, distillations were performed using the Advanced Distillation Curve apparatus on carefully selected samples consisting of gasoline blended with ethanol and heavy aromatic and oxygenated compounds with varying vapor pressures, including cumene, p-cymene, 4-tertbutyl toluene, anisole, and 4-methyl anisole. Samples collected during the distillation indicate an enrichment of the heavy aromatic or oxygenated additive with an increase in initial ethanol concentration from E0 to E30. A recently developed distillation and droplet evaporation model is used to explore the influence of dilution effects versus azeotrope interactions on the aromatic species enrichment. The results suggest that HOV-cooling effects as well as aromatic species enrichment behaviors should be considered in future development of predictive indices to forecast the PM potential of fuels containing oxygenated compounds with comparatively high HOV.« less

Synthesis and Anticancer Activities of Novel Guanylhydrazone and Aminoguanidine Tetrahydropyran Derivatives.

PubMed

Silva, Fábio Pedrosa Lins; Dantas, Bruna Braga; Faheina Martins, Gláucia Veríssimo; de Araújo, Demétrius Antônio Machado; Vasconcellos, Mário Luiz Araújo de Almeida

2016-06-21

In this paper we present the convenient syntheses of six new guanylhydrazone and aminoguanidine tetrahydropyran derivatives 2-7. The guanylhydrazone 2, 3 and 4 were prepared in 100% yield, starting from corresponding aromatic ketones 8a-c and aminoguanidine hydrochloride accessed by microwave irradiation. The aminoguanidine 5, 6 and 7 were prepared by reduction of guanylhydrazone 2-4 with sodium cyanoborohydride (94% yield of 5, and 100% yield of 6 and 7). The aromatic ketones 8a-c were prepared from the Barbier reaction followed by the Prins cyclization reaction (two steps, 63%-65% and 95%-98%). Cytotoxicity studies have demonstrated the effects of compounds 2-7 in various cancer and normal cell lines. That way, we showed that these compounds decreased cell viabilities in a micromolar range, and from all the compounds tested we can state that, at least, compound 3 can be considered a promising molecule for target-directed drug design.

Tracking oil and gas wastewater-derived organic matter in a hybrid biofilter membrane treatment system: A multi-analytical approach.

PubMed

Riley, Stephanie M; Ahoor, Danika C; Regnery, Julia; Cath, Tzahi Y

2018-02-01

Dissolved organic matter (DOM) present in oil and gas (O&G) produced water and fracturing flowback was characterized and quantified by multiple analytical techniques throughout a hybrid biological-physical treatment process. Quantitative and qualitative analysis of DOM by liquid chromatography - organic carbon detection (LC-OCD), liquid chromatography-high-resolution mass spectrometry (LC-HRMS), gas chromatography-mass spectrometry (GC-MS), and 3D fluorescence spectroscopy, demonstrated increasing removal of all groups of DOM throughout the treatment train, with most removal occurring during biological pretreatment and some subsequent removal achieved during membrane treatment. Parallel factor analysis (PARAFAC) further validated these results and identified five fluorescent components, including DOM described as humic acids, fulvic acids, proteins, and aromatics. Tryptophan-like compounds bound by complexation to humics/fulvics were most difficult to remove biologically, while aromatics (particularly low molecular weight neutrals) were more challenging to remove with membranes. Strong correlation among PARAFAC, LC-OCD, LC-HRMS, and GC-MS suggests that PARAFAC can be a quick, affordable, and accurate tool for evaluating the presence or removal of specific DOM groups in O&G wastewater. Copyright © 2017 Elsevier B.V. All rights reserved.

Fate and Transport of Polycyclic Aromatic Hydrocarbons in Upland Irish Headwater Lake Catchments

PubMed Central

Scott, Heidi E. M.; Aherne, Julian; Metcalfe, Chris D.

2012-01-01

Polycyclic aromatic hydrocarbons (PAHs) are a concern due to their carcinogenicity and propensity for transboundary atmospheric transport. Ireland is located on the western periphery of Europe and assumed to receive clean Atlantic air. As such, it has been used as an atmospheric reference for comparison to other regions. Nonetheless, few studies have evaluated concentrations of PAHs within the Irish environment. In the current study, PAHs were measured at five upland (500–800 masl) headwater lake catchments in coastal regions around Ireland, remote from industrial point source emissions. Semipermeable membrane devices were deployed in lakes for a 6-month period in July 2009, and topsoils were sampled from each catchment during October 2010. The concentrations of PAHs were low at most study sites with respect to other temperate regions. Homologue groups partitioned between lake and soil compartments based on their molecular weight were: “lighter” substances, such as Phenanthrene and Fluorene, were found in higher proportions in lakes, whereas “heavier” compounds, such as Chrysene and Benz[a]anthracene, were more prominent in soils. Concentrations of PAHs were highest at the east coast sites, potentially due to contributions from historical transboundary and regional combustion sources. PMID:23346024

Arylglycerol-γ-Formyl Ester as an Aromatic Ring Cleavage Product of Nonphenolic β-O-4 Lignin Substructure Model Compounds Degraded by Coriolus versicolor†

PubMed Central

Kawai, Shingo; Umezawa, Toshiaki; Higuchi, Takayoshi

1985-01-01

4-Ethoxy-3-methoxyphenylglycerol-γ-formyl ester (compound IV) was identified as a degradation product of both 4-ethoxy-3-methoxyphenylglycerol-β-syringaldehyde ether (compound I) and 4-ethoxy-3-methoxyphenylglycerol-β-2,6-dimethoxyphenyl ether (compound II) by a ligninolytic culture of Coriolus versicolor. An isotopic experiment with a 13C-labeled compound (compound II′) indicated that the formyl group of compound IV was derived from the β-phenoxyl group of β-O-4 dimer as an aromatic ring cleavage fragment. However, compound IV was not formed from 4-ethoxy-3-methoxyphenylglycerol-β-guaiacyl ether (compound III). γ-Formyl arylglycerol (compound IV) could be a precursor of 4-ethoxy-3-methoxyphenylglycerol (compound VI), because 3-(4-ethoxy-3-methoxyphenyl)-1-formyloxy propane (compound VII) was cleaved to give 3-(4-ethoxy-3-methoxyphenyl)-1-propanol (compound VIII) by C. versicolor. 4-Ethoxy-3-methoxyphenylglycerol-β,γ-cyclic carbonate (compound V), previously found as a degradation product of compound III by Phanerochaete chrysosporium (T. Umezawa, and T. Higuchi, FEBS Lett., 25:123-126, 1985), was also identified from the cultures with compound I, II, and III and degraded to give the arylglycerol (compound VI). An isotopic experiment with 13C-labeled compounds II′ and III′ indicated that the carbonate carbon of compound V was derived from the β-phenoxyl groups of β-O-4 substructure. PMID:16346950

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ma, Ruoshui; Guo, Mond; Lin, Kuan-ting

Lignin is the largest source of renewable material with an aromatic skeleton. However, due to the recalcitrant and heterogeneous nature of the lignin polymer as well as its complex side chain structures, it has been a challenge to effectively depolymerize lignin and produce high value chemicals with high selectivity. In this study, a highly efficient lignin-to-monomeric phenolic compounds (MPC) conversion method based on peracetic acid (PAA) treatment was reported. PAA treatment of two biorefinery lignin samples, diluted acid pretreated corn stover lignin (DACSL) and steam exploded spruce lignin (SESPL), led to complete solubilization and production of selective hydroxylated monomeric phenolicmore » compounds (MPC-H) and monomeric phenolic acid compounds (MPC-A) inclduing 4-hydroxy-2-methoxyphenol, p-hydroxybenzoic acid, vanillic acid, syringic acid, and 3,4-dihydroxybenzoic acid. The maximized MPCs yields obtained were 18% and 22% based on the initial weight of the lignin in SESPL and DACSL respectively. However, we found that the addition of niobium pentoxide catalyst to PAA treatment of lignin can significantly improve the MPC yields up to 47%. The key reaction steps and main mechanisms involved in this new lignin-to-MPC valorization pathway were investigated and elucidated.« less

Polycyclic aromatic hydrocarbons in Saccoglossus kowalewskyi (Agassiz)

NASA Astrophysics Data System (ADS)

Carey, D. A.; Farrington, J. W.

1989-08-01

Hydrocarbon extracts were analyzed from Saccoglossus kowalewskyi, a deposit-feeding enteropneust worm, and from surface sediments from Cape Cod, MA. Worms were held in experimental aquaria in sieved sediments and flowing seawater for four months and then fed sediments mixed with creosote, lampblack or clean sediment for two weeks as analogues of sediments containing degraded oil and pyrogenic compounds. Worms from all treatments contained polyaromatic hydrocarbons (PAHs) in amounts and composition that indicate that the worms were contaminated with weathered No. 2 fuel oil before our experimental treatment and that the contamination persisted for four months in clean conditions. The contamination was not detected in the clean sediments used in the experiment. The worms accumulated steroid transformation products in greater abundance than the odd chain n-alkanes that dominated the sediment extractions. This may indicate selective assimilation of algal detritus and microbial products over salt marsh detritus. Worms, actively feeding during the experiment, contained 1-3 × 10 -6 g g -1 dry weight of unknown brominated compounds which were not detected in the sediments. These compounds are similar to bromopyrroles found elsewhere in enteropneusts, polychaetes and bacteria and may cause substantial interference in analyses for some industrial pollutants.

Homogeneous purification and characterization of LePGT1--a membrane-bound aromatic substrate prenyltransferase involved in secondary metabolism of Lithospermum erythrorhizon.

PubMed

Ohara, Kazuaki; Mito, Koji; Yazaki, Kazufumi

2013-06-01

Membrane-bound type prenyltransferases for aromatic substrates play crucial roles in the biosynthesis of various natural compounds. Lithospermum erythrorhizon p-hydroxybenzoate: geranyltransferase (LePGT1), which contains multiple transmembrane α-helices, is involved in the biosynthesis of a red naphthoquinone pigment, shikonin. Taking LePGT1 as a model membrane-bound aromatic substrate prenyltransferase, we utilized a baculovirus-Sf9 expression system to generate a high yield LePGT1 polypeptide, reaching ~ 1000-fold higher expression level compared with a yeast expression system. Efficient solubilization procedures and biochemical purification methods were developed to extract LePGT1 from the membrane fraction of Sf9 cells. As a result, 80 μg of LePGT1 was purified from 150 mL culture to almost homogeneity as judged by SDS/PAGE. Using purified LePGT1, enzymatic characterization, e.g. substrate specificity, divalent cation requirement and kinetic analysis, was done. In addition, inhibition experiments revealed that aromatic compounds having two phenolic hydroxyl groups effectively inhibited LePGT1 enzyme activity, suggesting a novel recognition mechanism for aromatic substrates. As the first example of solubilization and purification of this membrane-bound protein family, the methods established in this study will provide valuable information for the precise biochemical characterization of aromatic prenyltransferases as well as for crystallographic analysis of this novel enzyme family. © 2013 The Authors Journal compilation © 2013 FEBS.

Polycyclic aromatic hydrocarbon metabolic network in Mycobacterium vanbaalenii PYR-1.

PubMed

Kweon, Ohgew; Kim, Seong-Jae; Holland, Ricky D; Chen, Hongyan; Kim, Dae-Wi; Gao, Yuan; Yu, Li-Rong; Baek, Songjoon; Baek, Dong-Heon; Ahn, Hongsik; Cerniglia, Carl E

2011-09-01

This study investigated a metabolic network (MN) from Mycobacterium vanbaalenii PYR-1 for polycyclic aromatic hydrocarbons (PAHs) from the perspective of structure, behavior, and evolution, in which multilayer omics data are integrated. Initially, we utilized a high-throughput proteomic analysis to assess the protein expression response of M. vanbaalenii PYR-1 to seven different aromatic compounds. A total of 3,431 proteins (57.38% of the genome-predicted proteins) were identified, which included 160 proteins that seemed to be involved in the degradation of aromatic hydrocarbons. Based on the proteomic data and the previous metabolic, biochemical, physiological, and genomic information, we reconstructed an experiment-based system-level PAH-MN. The structure of PAH-MN, with 183 metabolic compounds and 224 chemical reactions, has a typical scale-free nature. The behavior and evolution of the PAH-MN reveals a hierarchical modularity with funnel effects in structure/function and intimate association with evolutionary modules of the functional modules, which are the ring cleavage process (RCP), side chain process (SCP), and central aromatic process (CAP). The 189 commonly upregulated proteins in all aromatic hydrocarbon treatments provide insights into the global adaptation to facilitate the PAH metabolism. Taken together, the findings of our study provide the hierarchical viewpoint from genes/proteins/metabolites to the network via functional modules of the PAH-MN equipped with the engineering-driven approaches of modularization and rationalization, which may expand our understanding of the metabolic potential of M. vanbaalenii PYR-1 for bioremediation applications.

Crystal structures of HIV-1 nonnucleoside reverse transcriptase inhibitors: N-benzyl-4-methyl-benzimidazoles

NASA Astrophysics Data System (ADS)

Ziółkowska, Natasza E.; Michejda, Christopher J.; Bujacz, Grzegorz D.

2009-07-01

HIV-1 nonnucleoside reverse transcriptase inhibitors are potentially specific and effective drugs in AIDS therapy. The presence of two aromatic systems with an angled orientation in the molecule of the inhibitor is crucial for interactions with HIV-1 RT. The inhibitor drives like a wedge into the cluster of aromatic residues of RT HIV-1 and restrains the enzyme in a conformation that blocks the chemical step of nucleotide incorporation. Structural studies provide useful information for designing new, more active inhibitors. The crystal structures of four NNRTIs are presented here. The investigated compounds are derivatives of N-benzyl-4-methyl-benzimidazole with various aliphatic and aromatic substituents at carbon 2 positions and a 2,6-dihalogeno-substituted N-benzyl moiety. Structural data reported here show that the conformation of the investigated compounds is relatively rigid. Such feature is important for the nonnucleoside inhibitor binding to HIV-1 reverse transcriptase.

Use of constant wavelength synchronous spectrofluorimetry for identification of polycyclic aromatic hydrocarbons in air particulate samples

NASA Astrophysics Data System (ADS)

Sharma, Homdutt; Jain, V. K.; Khan, Zahid H.

2013-05-01

We have developed a simple, rapid, inexpensive method for the identification of fluoranthene (Flan), benz(a)anthracene (BaA), benzo(a)pyrene (BaP), benzo(k)fluoranthene (BkF), pyrene (Pyr), benz(ghi)perylene (BghiP) in suspended particulate matter in an urban environment of Delhi. Suspended particulate matter samples of 24 h duration were collected on glass fiber filter papers. Polycyclic aromatic hydrocarbons (PAHs) were extracted from the filter papers using dichloromethane (DCM) and hexane with ultrasonication method. Comparison of the characteristic emission of spectra of PAHs with standard spectra indicated the degree of condensation of aromatic compounds present in investigated mixtures. It was also possible to identify some individual compounds. However, this identification could be more effective with the use of the respective values of Δλ parameter for each particular component of the mixture.

Aromatics and phenols from catalytic pyrolysis of Douglas fir pellets in microwave with ZSM-5 as a catalyst

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wang, Lu; Lei, Hanwu; Ren, Shoujie

Microwave assisted catalytic pyrolysis was investigated to convert Douglas fir pellets to bio-oils by a ZSM-5 Zeolite catalyst. A central composite experimental design (CCD) was used to optimize the catalytic pyrolysis process. The effects of reaction time, temperature and catalyst to biomass ratio on the bio-oil, syngas, and biochar yields were determined. GC/MS analysis results showed that the bio-oil contained a series of important and useful chemical compounds. Phenols, guaiacols, and aromatic hydrocarbons were the most abundant compounds which were about 50-82 % in bio-oil depending on the pyrolysis conditions. Comparison between the bio-oils from microwave pyrolysis with and withoutmore » catalyst showed that the catalyst increased the content of aromatic hydrocarbons and phenols. A reaction pathway was proposed for microwave assisted catalyst pyrolysis of Douglas fir pellets.« less

Development of Chemical and Metabolite Sensors for Rhodococcus opacus PD630.

PubMed

DeLorenzo, Drew M; Henson, William R; Moon, Tae Seok

2017-10-20

Rhodococcus opacus PD630 is a nonmodel, Gram-positive bacterium that possesses desirable traits for biomass conversion, including consumption capabilities for lignocellulose-based sugars and toxic lignin-derived aromatic compounds, significant triacylglycerol accumulation, relatively rapid growth rate, and genetic tractability. However, few genetic elements have been directly characterized in R. opacus, limiting its application for lignocellulose bioconversion. Here, we report the characterization and development of genetic tools for tunable gene expression in R. opacus, including: (1) six fluorescent reporters for quantifying promoter output, (2) three chemically inducible promoters for variable gene expression, and (3) two classes of metabolite sensors derived from native R. opacus promoters that detect nitrogen levels or aromatic compounds. Using these tools, we also provide insights into native aromatic consumption pathways in R. opacus. Overall, this work expands the ability to control and characterize gene expression in R. opacus for future lignocellulose-based fuel and chemical production.

Model compound study of the pathways for aromatic hydrocarbon formation in soot.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Tomczyk, N. A.; Hunt, J. E.; Winans, R. E.

2002-04-29

To explore the mechanisms for formation of aromatic hydrocarbons as precursors to soot, a model system using combustion of biphenyl in a fuel rich flame is studied. The soots acquired at three different temperatures are solvent extracted and the extract characterized by both GCMS and high resolution mass spectrometry. A description of the NMR results for the whole soots has been published (1). The production of most products could be rationalized from the coupling of biphenyls and subsequent aromatic species and the addition of acetylenes to existing aromatic molecules. Early work by Badger on pyrolysis of hydrocarbons is used inmore » developing these schemes (2). The reaction schemes to produce larger aromatic hydrocarbons will be discussed. Richter and Howard have discussed in detail potential reaction mechanisms in the formation of aromatics as precursors to soot (3).« less

Biomonitoring of polycyclic aromatic compounds in the urine of mining workers occupationally exposed to diesel exhaust.

PubMed

Seidel, Albrecht; Dahmann, Dirk; Krekeler, Horst; Jacob, Juergen

2002-02-01

Diesel exhaust is considered a probable human carcinogen by the IARC. Biomonitoring of workers occupationally exposed to diesel exhaust was performed to determine their internal burden of diesel associated aromatic compounds. Personal air sampling also allowed to determine the exposure of the miners at their work place towards several polycyclic aromatic hydrocarbons (PAH) and nitro-arenes, the latter of which are thought to be specific constituents of diesel exhaust. For biomonitoring the urine of 18 underground salt miners was collected during and after their shift for 24-hours. half of the 18 miners were smokers. The urinary levels of 1-hydroxypyrene and hydroxylated phenanthrene metabolites were determined as biomarkers of PAH exposure, whereas urinary levels of some aromatic amines were chosen to monitor exposure towards specific nitro-arenes from diesel exhaust like 1-nitropyrene and 3-nitrobenzanthrone and to monitor the human burden by these compounds from inhaled cigarette smoke. Non-smoking workers exposed to diesel exhaust excrete an average level of about 4 micrograms phenanthrene metabolites, whereas the urinary levels in smokers were up to 3-fold higher. In summary the results indicate that (i) diesel exposure led to an increase of PAH metabolism in the workers examined, most probably by an induction of cytochrome P450 (ii) smokers could be identified in accordance with earlier studies by their increased ratio of phenanthrene metabolites derived from 1,2- and 3,4-oxidation and their higher amounts of excreted 1-naphthylamine, and (iii) the excreted amounts of aromatic amines found as metabolites of the nitro-arenes were about 5- to 10-fold higher as one might expect from the levels determined by personal air sampling at the workplace of the individuals.

Solvent-resistant sol-gel polydimethyldiphenylsiloxane coating for on-line hyphenation of capillary microextraction with high-performance liquid chromatography.

PubMed

Segro, Scott S; Malik, Abdul

2008-09-26

A sol-gel polydimethyldiphenylsiloxane (PDMDPS) coating was developed for capillary microextraction on-line hyphenated with high-performance liquid chromatography (HPLC). This coating was created using methyltrimethoxysilane (MTMS) as the sol-gel precursor and di-hydroxy-terminated PDMDPS as the sol-gel active polymer. The methyl and phenyl groups on the sol-gel active polymer and the methyl groups on the sol-gel precursor ultimately turned into pendant groups providing the ability to extract non-polar analytes. A 40-cm segment of 0.25 mm I.D. fused silica capillary containing the sol-gel PDMDPS coating was installed as an external sampling loop in an HPLC injection port. Aqueous samples containing polycyclic aromatic hydrocarbons (PAHs), aromatic compounds, ketones, and aldehydes were passed through this capillary wherein the analytes were extracted by the sol-gel coating. The extracted analytes were then transferred to the HPLC column using isocratic or gradient elution with an acetonitrile/water mobile phase. This capillary demonstrated excellent extraction capability for non-polar (e.g., polycyclic aromatic hydrocarbons and aromatic compounds) as well as moderately polar compounds, such as aromatic amines, ketones, and aldehydes. The test results indicate that PDMDPS can be successfully immobilized into a sol-gel network and that the resulting solvent-resistant sol-gel organic-inorganic hybrid coating can be effectively used for on-line hyphenation of capillary microextraction with high-performance liquid chromatography. The test results also indicate that the sol-gel PDMDPS coated capillary is resistant to high-temperature solvents, making it suitable for applications in high-temperature HPLC. To the best of our knowledge, this is the first report on the creation of a silica-based sol-gel PDMDPS coating used in capillary microextraction on-line hyphenated to HPLC.

Lasiodiplodia sp. ME4-2, an endophytic fungus from the floral parts of Viscum coloratum, produces indole-3-carboxylic acid and other aromatic metabolites.

PubMed

Qian, Chao-Dong; Fu, Yu-Hang; Jiang, Fu-Sheng; Xu, Zheng-Hong; Cheng, Dong-Qing; Ding, Bin; Gao, Cheng-Xian; Ding, Zhi-Shan

2014-11-30

Studies on endophytes, a relatively under-explored group of microorganisms, are currently popular amongst biologists and natural product researchers. A fungal strain (ME4-2) was isolated from flower samples of mistletoe (Viscum coloratum) during a screening program for endophytes. As limited information on floral endophytes is available, the aim of the present study is to characterise fungal endophytes using their secondary metabolites. ME4-2 grew well in both natural and basic synthetic media but produced no conidia. Sequence analysis of its internal transcribed spacer rDNA demonstrated that ME4-2 forms a distinct branch within the genus Lasiodiplodia and is closely related to L. pseudotheobromae. This floral endophyte was thus identified as Lasiodiplodia sp. based on its molecular biological characteristics. Five aromatic compounds, including cyclo-(Trp-Ala), indole-3-carboxylic acid (ICA), indole-3-carbaldehyde, mellein and 2-phenylethanol, were found in the culture. The structures of these compounds were determined using spectroscopic methods combined with gas chromatography. To the best of our knowledge, our work is the first to report isolation of these aromatic metabolites from a floral endophyte. Interestingly, ICA, a major secondary metabolite produced by ME4-2, seemed to be biosynthesized via an unusual pathway. Furthermore, our results indicate that the fungus ME4-2 is a potent producer of 2-phenylethanol, which is a common component of floral essential oils. This study introduces a fungal strain producing several important aromatic metabolites with pharmaceutical or food applications and suggests that endophytic fungi isolated from plant flowers are promising natural sources of aromatic compounds.

Pyridine group assisted addition of diazo-compounds to imines in the 3-CC reaction of 2-aminopyridines, aldehydes, and diazo-compounds.

PubMed

Gulevich, Anton V; Helan, Victoria; Wink, Donald J; Gevorgyan, Vladimir

2013-02-15

A novel three-component coupling (3-CC) reaction of 2-aminoazines, aromatic aldehydes, and diazo-compounds producing polyfunctional β-amino-α-diazo-compounds has been developed. The reaction features an unprecedented heterocycle-assisted addition of a diazo-compound to an imine. The obtained diazoesters were efficiently converted into valuable heterocycles as well as β-amino acid derivatives.

Synthesis of Aromatic Aza-metallapentalenes from Metallabenzene via Sequential Ring Contraction/Annulation

NASA Astrophysics Data System (ADS)

Wang, Tongdao; Han, Feifei; Huang, Haiping; Li, Jinhua; Zhang, Hong; Zhu, Jun; Lin, Zhenyang; Xia, Haiping

2015-04-01

The concept of aromaticity has long played an important role in chemistry and continues to fascinate both experimentalists and theoreticians. Among the archetypal aromatic compounds, heteroaromatics are particularly attractive. Recently, substitution of a transition-metal fragment for a carbon atom in the anti-aromatic hydrocarbon pentalene has led to the new heteroaromatic osmapentalenes. However, construction of the aza-homolog of osmapentalenes cannot be accomplished by a similar synthetic manipulation. Here, we report the synthesis of aza-osmapentalenes by sequential ring contraction/annulation reactions of osmabenzenes via osmapentafulvenes. Nuclear magnetic resonance spectra, X-ray crystallographic analysis, and DFT calculations all suggest that these aza-osmapentalenes exhibit aromatic character. Thus, the stepwise transformation of metallabenzenes to metallapentafulvenes and then aza-metallapentalenes provides an efficient and facile synthetic route to these bicyclic heteroaromatics.