32 results match your criteria set alkylbenzenes

Experimental determination of phase ratio of C8 columns employing retention factors and octane-mobile phase partition coefficients of homologous series of linear alkylbenzenes.

J Chromatogr A 2020 Dec 2;1634:461668. Epub 2020 Nov 2.

Department of Chemistry and Center of Excellence for Innovation in Chemistry and Flow Innovation-Research for Science and Technology Laboratories (FIRST Labs), Faculty of Science, Mahidol University, Rama VI Rd., Bangkok 10400, Thailand. Electronic address:

This work proposes an experimental method for the estimation of the phase ratio of reversed-phase C8 columns by employing the equation log(k)=alog(K)+log(Φ), where k is the retention factor, Kis the octane-mobile phase partition coefficient, a is a proportionality constant and Φ is the phase ratio (defined as volume ratio of the stationary phase to the mobile phase). The immiscible liquid octane and mobile phase are chosen as the surrogate model for the C8 stationary phase and mobile phase of the chromatographic system. The octane-mobile phase is used for measuring the partition coefficient K of six compounds of the homologous series of linear alkylbenzenes, viz. Read More

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December 2020

Emission behavior, environmental impact and priority-controlled pollutants assessment of volatile organic compounds (VOCs) during asphalt pavement construction based on laboratory experiment.

J Hazard Mater 2020 11 15;398:122904. Epub 2020 May 15.

State Key Laboratory of Silicate Materials for Architectures, Wuhan University of Technology, Wuhan 430070, China. Electronic address:

Volatile organic compounds (VOCs) release from asphalt pavement construction is a potential emission source. The detailed emission behaviors were simulated in the laboratory, and the corresponding environmental impact was investigated as well. A set of dedicated devices were applied to mirror 3 representative scenarios namely mixture plant, transportation and paving processes with VOCs emission concentrations varied from 4. Read More

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November 2020

Short-term spatiotemporal biomarker changes in oysters transplanted to an anthropized estuary in Southern Brazil.

Sci Total Environ 2020 Mar 10;709:136042. Epub 2019 Dec 10.

Department of Scientific and Technological Education, Santa Catarina State University, Florianópolis 88035-001, Brazil. Electronic address:

Estuarine ecosystems are increasingly being affected by pollution caused by anthropogenic activities. In this study, Crassostrea gasar oysters were transplanted and maintained for seven days at three sites (S1, S2, and S3) in the Laguna Estuarine System (LES)-situated in southern Brazil-that has been exposed to multiple anthropic stresses. On the basis of the concentrations of metal and organic pollutants in oysters, we identified marked spatial variations in pollutant levels, with S3 showing the highest concentration of Ag, Fe, Ni, Zn, and total polycyclic aromatic hydrocarbons (PAHs), polychlorinated biphenyls (PCBs), and linear alkylbenzenes (LABs), followed by S2 and S1. Read More

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Impacts of dredging on biomarkers responses of caged bivalves in a semi-arid region (Ceará State, NE Brazil).

Mar Environ Res 2019 Oct 3;151:104784. Epub 2019 Sep 3.

Núcleo de Estudos em Poluição e Ecotoxicologia Aquática, UNESP - São Vicente, Brazil.

In this study, the performance of two native bivalves in responding to sediment resuspension was investigated during dredging operations of a semi-arid bay (Mucuripe, NE Brazil). The clam Anomalocardia flexuosa and the oyster Crassostrea rhizophorae were selected and caged in two sites influenced by the dredging plume. We assessed the bioaccumulation of metals and hydrocarbons in both species as biomarkers of exposure and then, biomarkers' responses were assessed in gills and digestive glands over a 28 days period, at 7 days intervals: the activities of phase I and II, and antioxidant enzymes, levels of lipid peroxidation and DNA strand breaks. Read More

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October 2019

Thermodynamics of Adsorption on Graphenic Surfaces from Aqueous Solution.

J Chem Theory Comput 2019 Feb 11;15(2):1302-1316. Epub 2019 Jan 11.

Institute of Computational Comparative Medicine, Nanotechnology Innovation Center of Kansas State, Department of Anatomy and Physiology , Kansas State University , Manhattan , Kansas 66506-5802 , United States.

Adsorption of organic molecules from aqueous solution to the surface of carbon nanotubes or graphene is an important process in many applications of these materials. Here we use molecular dynamics simulation, supplemented by analytical chemistry, to explore in detail the adsorption thermodynamics of a diverse set of aromatic compounds on graphenic materials, elucidating the effects of the solvent, surface coverage, surface curvature, defects, and functionalization by hydroxy groups. We decompose the adsorption free energies into entropic and enthalpic components and find that different classes of compounds-such as phenols, benzoates, and alkylbenzenes-can easily be distinguished by the relative contributions of entropy and enthalpy to their adsorption free energies. Read More

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February 2019

Preparation of a monolithic column with a mixed-mode stationary phase of reversed-phase/hydrophilic interaction for capillary liquid chromatography.

J Sep Sci 2019 Feb 4;42(3):662-669. Epub 2019 Jan 4.

State Key Laboratory of Bioorganic and Natural Products Chemistry, Center for Excellence in Molecular Synthesis, Shanghai Institute of Organic Chemistry, University of Chinese Academy of Sciences, Shanghai, P. R. China.

A monolithic capillary column with a mixed-mode stationary phase of reversed-phase/hydrophilic interaction chromatography was prepared for capillary liquid chromatography. The monolith was created by an in-situ copolymerization of a homemade monomer N,N-dimethyl-N-acryloxyundecyl-N-(3-sulfopropyl) ammonium betaine and a crosslinker pentaerythritol triacrylate in a binary porogen agent consisting of methanol and isopropanol. The functional monomer was designed to have a highly polar zwitterionic sulfobetaine terminal group and a hydrophobic long alkyl chain moiety. Read More

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February 2019

Impact of Molecular Structure on Properties of n-Hexadecane and Alkylbenzene Binary Mixtures.

J Phys Chem B 2018 06 15;122(25):6595-6603. Epub 2018 Jun 15.

Department of Chemistry , United States Naval Academy , Annapolis , Maryland 21402 , United States.

Because of the complexity of petroleum-based fuels, researchers typically use simplified mixtures, known as surrogates, to study combustion behavior and to attempt to identify how physical properties are related to combustion. The process of determining the surrogate composition to yield a desired set of thermophysical properties can be a complicated and time-consuming task. As a result, the use of computer simulations to narrow the number of possible surrogate compositions is beginning to be explored. Read More

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Conformational explosion: Understanding the complexity of short chain para-dialkylbenzene potential energy surfaces.

J Chem Phys 2018 May;148(18):184304

Department of Chemistry, Purdue University, West Lafayette, Indiana 47907-2050, USA.

The single-conformation ultraviolet and infrared spectroscopy of three short-chain para-dialkylbenzenes (para-diethylbenzene, para-dipropylbenzene, and para-dibutylbenzene) is reported for the jet-cooled, isolated molecules. The present study builds off previous work on single-chain n-alkylbenzenes, where an anharmonic local mode Hamiltonian method was developed to account for stretch-bend Fermi resonance in the alkyl CH stretch region [D. P. Read More

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Identifying the first folded alkylbenzene ultraviolet, infrared, and Raman spectroscopy of pentylbenzene through decylbenzene.

Chem Sci 2017 Aug 23;8(8):5305-5318. Epub 2017 May 23.

Department of Chemistry , Purdue University , West Lafayette , IN 47907 , USA . Email:

The conformational preferences of pentyl- through decylbenzene are studied under jet-cooled conditions in the gas phase. Laser-induced fluorescence excitation spectra, fluorescence-dip infrared spectra in the alkyl CH stretch region, and Raman spectra are combined to provide assignments for the observed conformers. Density functional theory calculations at the B3LYP-D3BJ/def2TZVP level of theory provide relative energies and normal mode vibrations that serve as inputs for an anharmonic local mode theory introduced in earlier work on alkylbenzenes with = 2-4. Read More

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Land Use Regression Models for Alkylbenzenes in a Middle Eastern Megacity: Tehran Study of Exposure Prediction for Environmental Health Research (Tehran SEPEHR).

Environ Sci Technol 2017 Aug 17;51(15):8481-8490. Epub 2017 Jul 17.

Department of Epidemiology and Public Health, Swiss Tropical and Public Health Institute , Basel 4051, Switzerland.

Land use regression (LUR) has not been applied thus far to ambient alkylbenzenes in highly polluted megacities. We advanced LUR models for benzene, toluene, ethylbenzene, p-xylene, m-xylene, o-xylene (BTEX), and total BTEX using measurement based estimates of annual means at 179 sites in Tehran megacity, Iran. Overall, 520 predictors were evaluated, such as The Weather Research and Forecasting Model meteorology predictions, emission inventory, and several new others. Read More

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Maximizing performance in supercritical fluid chromatography using low-density mobile phases.

J Chromatogr A 2016 Oct 13;1468:217-227. Epub 2016 Sep 13.

Waters Corporation, Instrument/Core Research/Fundamental, Milford, MA 01757, USA.

The performance of a 3.0mm×150mm column packed with 1.8μm fully porous HSS-SB-C particles was investigated in supercritical fluid chromatography (SFC) with low-density, highly expansible carbon dioxide. Read More

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October 2016

Unexpected retention and efficiency behaviors in supercritical fluid chromatography: A thermodynamic interpretation.

Fabrice Gritti

J Chromatogr A 2016 Oct 12;1468:209-216. Epub 2016 Sep 12.

Waters Corporation, Instrument/Core Research/Fundamental, Milford, MA 01757, USA. Electronic address:

Experimental conditions leading to unexpected shift in retention, band compression, and to band enlargement of small molecules in supercritical fluid chromatography are reported. The stationary phase is a 3.0mm×150mm column packed with 1. Read More

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October 2016

Pathogenic Yet Environmentally Friendly? Black Fungal Candidates for Bioremediation of Pollutants.

Geomicrobiol J 2016 Mar 25;33(3-4):308-317. Epub 2016 Feb 25.

University of Natural Resources and Life Sciences Vienna, VIBT-Extremophile Center , Vienna , Austria.

A collection of 163 strains of black yeast-like fungi from the CBS Fungal Biodiversity Center (Utrecht, The Netherlands), has been screened for the ability to grow on hexadecane, toluene and polychlorinated biphenyl 126 (PCB126) as the sole carbon and energy source. These compounds were chosen as representatives of relevant environmental pollutants. A microtiter plate-based culture assay was set up in order to screen the fungal strains for growth on the selected xenobiotics versus glucose, as a positive control. Read More

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[Preparation and evaluation of N-acryloyltris (hydroxymethyl) aminomethane-bonded chromatographic stationary phase].

Se Pu 2015 Sep;33(9):917-21

The present study described the preparation of N-acryloyltris (hydroxymethyl) aminomethane-bonded silica (NAS) stationary phase based on "thiol-ene" click chemistry. The composition of the surface grafts of NAS stationary phase was determined by elemental analysis and the results demonstrated the successful introduction of the N-acryloyltris (hydroxymethyl) aminomethane groups to the silica surface. Similar elemental composition of three batches of the NAS stationary phases exhibited good reproducibility of the preparation strategy. Read More

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September 2015

Development of a decaaza-cyclophane stationary phase for high-performance liquid chromatography.

J Sep Sci 2015 Jan 29;38(1):60-6. Epub 2014 Nov 29.

Henan University of Traditional Chinese Medicine, Zhengzhou, P.R. China.

A new stationary phase for high-performance liquid chromatography was prepared by covalently bonding a heteroatom-bridged cyclophane onto silica gel using 3-aminopropyltriethoxysilane as the coupling reagent. The structure of the new material was characterized by infrared spectroscopy, elemental analysis, and thermogravimetric analysis. The linear solvation energy relationship method was successfully employed to evaluate the new phase with a set of 25 solutes, and compared with octadecylsilyl and p-tert-butyl-calix[4]arene bonded stationary phases. Read More

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January 2015

Development of a V-shape bis(tetraoxacalix[2]arene[2]triazine) stationary phase for high performance liquid chromatography.

Talanta 2014 Dec 1;130:63-70. Epub 2014 Jul 1.

College of Chemistry and Molecular Engineering, Key Laboratory of Chemical Biology and Organic Chemistry of Henan, Zhengzhou University, Daxue Road 75, Zhengzhou 450052, PR China. Electronic address:

A new stationary phase for high-performance liquid chromatography was prepared by covalently bonding a V-shape cage heteroatom-bridged calixarene onto silica gel using 3-aminopropyltriethoxysilane as coupling reagent. The structure of the new material was characterized by infrared spectroscopy, elemental analysis and thermogravimetric analysis. Linear solvation energy relationship method was successfully employed to evaluate the new phase with a set of 34 solutes. Read More

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December 2014

Energetics of nonbonded ortho interactions in alkylbenzenes.

J Phys Chem A 2013 Apr 25;117(13):2873-8. Epub 2013 Mar 25.

Centro de Química e Bioquímica, Faculdade de Ciências, Universidade de Lisboa, 1749-016 Lisboa, Portugal.

The gas-phase enthalpies of formation for a set of ortho-substituted alkylbenzenes were obtained from CCSD(T*)-F12 and W1-F12 calculations. Most values are in keeping with available experimental data. The gas-phase enthalpies of formation of 1-ethyl-2-propylbenzene, 1-ethyl-2-isopropylbenzene, 1,2-diisopropylbenzene, 1,2,4-triethylbenzene, and 1,2,4,5-tetraethylbenzene, for which no experimental data are available, were determined as -46. Read More

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The effects of season and soil type on microbial degradation of gasoline residues from incendiary devices.

Anal Bioanal Chem 2013 Feb 16;405(5):1593-9. Epub 2012 Dec 16.

Department of Chemistry and Chemical Biology, Indiana University Purdue University Indianapolis (IUPUI), Indianapolis, IN 46202, USA.

The primary task of a fire debris chemist is to determine if there is an ignitable liquid present in a fire debris sample and, if so, to classify it according to its boiling point and carbon number range. However, in organic-rich substrates such as soil, the ignitable liquid residue is subject to microbial degradation due to the ease with which bacteria can metabolize the various hydrocarbons present. This is a rapid process which is problematic in many forensic laboratories as fire debris is often stored for extended periods of time due to case backlog. Read More

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February 2013

Effect of the thermal environment on the efficiency of packed columns in supercritical fluid chromatography.

J Chromatogr A 2012 Nov 12;1266:149-57. Epub 2012 Oct 12.

Department of Chemistry and Biochemistry, University of Minnesota Duluth, Duluth, MN 55812, USA.

When a packed column is operated at temperatures and pressures near the critical point in supercritical fluid chromatography, the thermal environment in which it is placed has a significant impact on retention and efficiency. We measured the retention factors, plate heights, and related parameters for elution of a test mixture of alkylbenzenes with 5% methanol/95% carbon dioxide mobile phase on a 250 mm × 4.6 mm i. Read More

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November 2012

Prompt HO2 formation following the reaction of OH with aromatic compounds under atmospheric conditions.

J Phys Chem A 2012 Jun 24;116(24):6015-26. Epub 2012 Jan 24.

Institut für Energie- und Klimaforschung IEK-8, Troposphäre, Forschungszentrum Jülich GmbH, 52425 Jülich, Germany.

The secondary formation of HO(2) radicals following OH + aromatic hydrocarbon reactions in synthetic air under normal pressure and temperature was investigated in the absence of NO after pulsed production of OH radicals. OH and HO(x) (=OH + HO(2)) decay curves were recorded using laser-induced fluorescence after gas-expansion. The prompt HO(2) yields (HO(2) formed without preceding NO reactions) were determined by comparison to results obtained with CO as a reference compound. Read More

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Predicting hydration Gibbs energies of alkyl-aromatics using molecular simulation: a comparison of current force fields and the development of a new parameter set for accurate solvation data.

Phys Chem Chem Phys 2011 Oct 31;13(38):17384-94. Epub 2011 Aug 31.

Laboratory of Separation and Reaction Engineering, Departamento de Engenharia Química, Faculdade de Engenharia, Universidade do Porto, Rua do Dr. Roberto Frias, 4200-465 Porto, Portugal.

The Gibbs energy of hydration is an important quantity to understand the molecular behavior in aqueous systems at constant temperature and pressure. In this work we review the performance of some popular force fields, namely TraPPE, OPLS-AA and Gromos, in reproducing the experimental Gibbs energies of hydration of several alkyl-aromatic compounds--benzene, mono-, di- and tri-substituted alkylbenzenes--using molecular simulation techniques. In the second part of the paper, we report a new model that is able to improve such hydration energy predictions, based on Lennard Jones parameters from the recent TraPPE-EH force field and atomic partial charges obtained from natural population analysis of density functional theory calculations. Read More

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October 2011

Mixed ligand monolithic columns for reversed-phase capillary electrochromatography via hydrophobic and π interactions.

Electrophoresis 2011 Apr 4;32(9):1044-53. Epub 2011 Apr 4.

Department of Chemistry, Oklahoma State University, Stillwater, OK, USA.

Novel mixed ligand monoliths (MLM) for capillary electrochromatography (CEC) of a wide range of solutes differing in both polarity and size were introduced. The MLM capillary columns were based on the different compositions of octadecyl acrylate (ODA) and 2-naphthyl methacrylate (NAPM) monomers in the presence of trimethylolpropane trimethacrylate (TRIM) crosslinker and a ternary porogenic solvent made up of cyclohexanol, ethylene glycol, and water. As expected, the magnitude of the electroosmotic flow (EOF) changed with the composition of the MLM. Read More

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Pollutant emissions from gasoline combustion. 1. Dependence on fuel structural functionalities.

Environ Sci Technol 2008 Aug;42(15):5615-21

Department of Chemical Engineering, The University of Utah, Salt Lake City, Utah 84112, USA.

To study the formation of air pollutants and soot precursors (e.g., acetylene, 1,3-butadiene, benzene, and higher aromatics) from aliphatic and aromatic fractions of gasoline fuels, the Utah Surrogate Mechanisms is extended to include submechanisms of gasoline surrogate compounds using a set of mechanism generation techniques. Read More

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A quantitative structure activity analysis on the relative sensitivity of the olfactory and the nasal trigeminal chemosensory systems.

Chem Senses 2007 Sep 14;32(7):711-9. Epub 2007 Jun 14.

Department of Chemistry, University College London, 20 Gordon Street, London WC1H OAJ, UK.

We have applied a quantitative structure-activity relationship (QSAR) approach to analyze the chemical parameters that determine the relative sensitivity of olfaction and nasal chemesthesis to a common set of volatile organic compounds (VOCs). We used previously reported data on odor detection thresholds (ODTs) and nasal pungency thresholds (NPTs) from 64 VOCs belonging to 7 chemical series (acetate esters, carboxylic acids, alcohols, aliphatic aldehydes, alkylbenzenes, ketones, and terpenes). The analysis tested whether NPTs could be used to separate out "selective" chemosensory effects (i. Read More

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September 2007

Optimized intermolecular potential for aromatic hydrocarbons based on anisotropic united atoms. III. Polyaromatic and naphthenoaromatic hydrocarbons.

J Phys Chem B 2005 Feb;109(7):2970-6

Laboratoire de Chimie Physique, Université de Paris Sud, Bâtiment 349, 91405 Orsay Cedex, France.

In this third article of the series, a new anisotropic united atoms (AUA) intermolecular potential parameter set has been proposed for the carbon force centers connecting the aromatic rings of polyaromatic hydrocarbons to predict thermodynamic properties using both the Gibbs ensemble and NPT Monte Carlo simulations. The model uses the same parameters as previous AUA models used for the aromatic CH force centers. The optimization procedure is based on the minimization of a dimensionless error criterion incorporating various thermodynamic data of naphthalene at 400 and 550 K. Read More

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February 2005

Characterization of transcriptional regulatory genes for biphenyl degradation in Rhodococcus sp. strain RHA1.

J Bacteriol 2004 Apr;186(7):2134-46

Department of Bioengineering, Nagaoka University of Technology, Kamitomioka, Nagaoka, Niigata, 940-2188, Japan.

Transcription of the bphA1A2A3A4C1B genes, which are responsible for the conversion of biphenyl and polychlorinated biphenyl to the meta-cleavage products in Rhodococcus sp. strain RHA1, was examined. The bphA1 promoter (P(bphA1)) was identified and was shown to promote transcription induction by biphenyl and ethylbenzene. Read More

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Relationship between olive oil:air, saline:air, and rat brain:air partition coefficients of organic solvents in vitro.

J Toxicol Environ Health A 2003 Oct;66(20):1985-98

Institute for Risk Assessment Sciences (IRAS), Toxicology Division, Utrecht University, Utrecht, the Netherlands.

Partition coefficients of 28 volatile organic solvents (13 alkylbenzenes, 10 chlorinated hydrocarbons, and 5 ketones) in olive oil, saline, and rat brain tissue homogenates were measured by equilibration in a closed vial and subsequent gas-chromatographic analysis of headspace air. The values of oil and saline partition coefficients correlate well with previously reported data. Brain partition coefficients were fit to a bilinear equation of the form P(brain:air) = alpha(o)P(oil:air) + alpha(s)P(saline:air) + c. Read More

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October 2003

Life-time studies with capillary electrochromatography columns operated under different conditions.

J Chromatogr A 2000 Oct;894(1-2):35-43

Institut fur Anorganische Chemie und Analytische Chemie, Johannes Gutenberg-Universität, Mainz, Germany.

A test system has been established to permit the monitoring of the life-time performance of several reversed- phase capillary electrochromatography (CEC) columns. The retention factors, k(cec), peak symmetry coefficients, lambda(sym), and column efficiencies, N, of three neutral n-alkylbenzene analytes, namely ethyl-, n-butyl- and n-pentylbenzenes, were determined for Hypersil 3 microm n-octylsilica and n-octadecylsilica packed into CEC capillary columns of 100 microm I.D. Read More

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October 2000

Use of artificial neural networks to predict the gas chromatographic retention index data of alkylbenzenes on carbowax-20M

Comput Chem 2000 Mar;24(2):171-9

Department of Chemistry, Lanzhou University, PR China.

Quantitative structure-activity relationships (QSARs) quantify the connection between the structure and properties of molecules and allow the prediction of properties from structural parameters. Models of relationships between structure and retention index of alkylbenzenes were constructed by means of a multilayer neural network using extended delta-bar-delta (EDBD) algorithms. The 165 group data belong to 129 alkylbenzenes at different temperatures on carbowax-20M. Read More

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Isopropylbenzene catabolic pathway in Pseudomonas putida RE204: nucleotide sequence analysis of the ipb operon and neighboring DNA from pRE4.

Biodegradation 1998 ;9(2):119-32

Gulf Ecology Division, National Health and Environmental Effects Research Laboratory, (NHEERL), U.S. Environmental Protection Agency, Gulf Breeze, FL, USA.

Pseudomonas putida RE204 employs a set of plasmid-specified enzymes in the catabolism of isopropylbenzene (cumene) and related alkylbenzenes. A 21,768 bp segment of the plasmid pRE4, whose sequence is discussed here, includes the ipb (isopropylbenzene catabolic) operon as well as associated genetic elements. The ipb operon, ipbAaAbAcAdBCEGFHD, encodes enzymes catalyzing the conversion of isopropylbenzene to isobutyrate, pyruvate, and acetyl-coenzyme A as well as an outer membrane protein (IpbH) of uncertain function. Read More

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December 1998