Sample records for alkane conversion chemistry

  1. Catalytic conversion of light alkanes. [Methane, ethane, propane and butanes

    SciTech Connect

    Lyons, J.E.

    1992-09-30

    The third and last quarterly report of 1992 on the Catalytic conversion of Light Alkanes reviews the work done between July, 1992 and September 30, 1992 on the Cooperative Agreement. The mission of this work is to devise a new catalyst which can be used in a simple economic process to convert the light alkanes in natural gas to oxygenate products which can either be used as clean-burning, high octane liquid fuels, as fuel components or as precursors to liquid hydrocarbon transportation fuel. During the past quarter we have continued to design, prepare, characterize and test novel catalysts for the mild selective reaction of light hydrocarbons with air or oxygen to produce alcohols directly. These catalysts are designed to form active metal oxo (MO) species and to be uniquely active for the homolytic cleavage of the carbon-hydrogen bonds in light alkanes producing intermediates which can form alcohols. We continue to investigate three molecular environments for the active catalytic species that we are trying to generate: electron-deficient macrocycles (PHASE I), polyoxometallates (PHASE II) and framework-substituted zeolites (PHASE III).

  2. Alkane Activation Initiated by Hydride Transfer: Co-conversion of Propane and Methanol over H-ZSM-5 Zeolite.

    PubMed

    Yu, Si-Min; Wu, Jian-Feng; Liu, Chong; Liu, Wei; Bai, Shi; Huang, Jun; Wang, Wei

    2015-06-15

    Co-conversion of alkane with another reactant over zeolite catalysts has emerged as a new approach to the long-standing challenge of alkane transformation. With the aid of solid-state NMR spectroscopy and GC-MS analysis, it was found that the co-conversion of propane and methanol can be readily initiated by hydride transfer at temperatures of ?449?K over the acidic zeolite H-ZSM-5. The formation of (13) C-labeled methane and singly (13) C-labeled n-butanes in selective labeling experiments provided the first evidence for the initial hydride transfer from propane to surface methoxy intermediates. The results not only provide new insight into carbocation chemistry of solid acids, but also shed light on the low-temperature transformation of alkanes for industrial applications. PMID:25959356

  3. Catalytic conversion of light alkanes: Quarterly report, January 1March 31, 1992

    Microsoft Academic Search

    J. Biscardi; P. T. Bowden; V. A. Durante; P. E. Jr. Ellis; H. B. Gray; R. G. Gorbey; R. C. Hayes; J. Hodge; M. Hughes; W. A. Langdale; J. E. Lyons; B. Marcus; D. Messick; R. A. Merrill; F. A. Moore; H. K. Jr. Myers; W. H. Seitzer; S. N. Shaikh; W. H. Tsao; R. W. Wagner; R. W. Warren; T. P. Wijesekera

    1997-01-01

    The first Quarterly Report of 1992 on the Catalytic Conversion of Light Alkanes reviews the work done between January 1. 1992 and March 31, 1992 on the Cooperative Agreement. The mission of this work is to devise a new catalyst which can be used in a simple economic process to convert the light alkanes in natural gas to oxygenate products

  4. Catalytic conversion of light alkanes: Proof of concept stage

    SciTech Connect

    Lyons, J.E.

    1995-06-01

    During the stage at which this work ended, our program consisted of two phases which were running concurrently, a research phase and a proof-of-concept phase. The function of the research phase is to design synthesize and perform laboratory tests on new materials in order to enhance the catalytic properties of the suprabiotic systems generated in our laboratories. Increases in catalytic activity and process selectivity as well as extensions of structure-activity relationships are examined. The research phase is intended to provide the process development phases with catalysts having superior properties for light alkane oxidation. The second concurrent phase, is the proof-of-concept phase. In this phase process development of oxidations which have succeeded in the research phase are carried out in a pre-pilot PDU. At the conclusion of the cooperative agreement we were developing a process for the conversion of isobutane to (TBA), We have identified two routes for this transformation: a one-step route directly from isobutane to TBA, and a two-step route in which the isobutane is oxidized first to tert-butyl hydroperoxide and then transformed into TBA catalytically. This paper presents the results of these activities.

  5. Catalytic conversion of C 6-alkanes over Pd\\/Al 2O 3 catalysts

    Microsoft Academic Search

    Maciej Skotak; Dariusz ?omot; Zbigniew Karpi?ski

    2002-01-01

    A comparable study of catalytic conversion of two C6-alkanes (n-hexane and 2,2-dimethybutane) has shown several analogies in the catalytic behavior of a series of differently loaded, chlorine-free Pd\\/Al2O3 catalysts. Different sample pretreatments have been used to modify the catalytic behavior. The catalytic performance of lowly reduced (at 573K) samples of Pd\\/Al2O3 catalysts is similar to that exhibited by unsupported or

  6. Catalytic conversion of light alkanes. Quarterly progress report, July 1, 1992--September 30, 1992

    SciTech Connect

    Lyons, J.E.

    1992-09-30

    The third and last quarterly report of 1992 on the Catalytic conversion of Light Alkanes reviews the work done between July, 1992 and September 30, 1992 on the Cooperative Agreement. The mission of this work is to devise a new catalyst which can be used in a simple economic process to convert the light alkanes in natural gas to oxygenate products which can either be used as clean-burning, high octane liquid fuels, as fuel components or as precursors to liquid hydrocarbon transportation fuel. During the past quarter we have continued to design, prepare, characterize and test novel catalysts for the mild selective reaction of light hydrocarbons with air or oxygen to produce alcohols directly. These catalysts are designed to form active metal oxo (MO) species and to be uniquely active for the homolytic cleavage of the carbon-hydrogen bonds in light alkanes producing intermediates which can form alcohols. We continue to investigate three molecular environments for the active catalytic species that we are trying to generate: electron-deficient macrocycles (PHASE I), polyoxometallates (PHASE II) and framework-substituted zeolites (PHASE III).

  7. Catalytic conversion of light alkanes -- research and proof-of-concept stages

    SciTech Connect

    Lyons, J.E.; Hancock, A.W. II

    1993-12-31

    Objective is to find new catalysts for direct reaction of methane, ethane, propane, butanes with O{sub 2} to form alcohols, and to develop practical processes for direct oxidative conversion of natural gas and its C{sub 1}-C{sub 4} components to produce alcohol-rich liquid oxygenates for use as alternative transportation fuels/environmentally superior reformulated gasolines. The proposed mechanism for oxidation activity of cytochrome P-450 and methane monoxygenase suggested that a catalyst able to reductively bind oxygen, not between Fe(III) center and a proton, but between two Fe(III) centers, might give the desired dioxygenase activity for alkane hydroxylation. Selective oxidation of light alkanes could be done by oxidation-active metal (Fe) centers in electron-deficient prophyrin-like macrocycles, polyoxoanions, and zeolites. In the isobutane conversion to tert-butanol proof-of-concept, it was found that nitro groups on the periphery of Fe porphyrin complexes give the greatest increase in Fe(III)/(II) reduction potential. 8 figs, 6 tabs, 40 refs.

  8. Chemistry of energy conversion and storage.

    PubMed

    Su, Dang Sheng

    2012-03-12

    Energy is a big issue in our society, fueled by growing awareness of the finite resources of liquid fossil fuels and the noticeable changes in our climate resulting from its consumption. The general consensus is that there should be a well-considered roadmap towards a future energy scenario, with the replacement of fossil energy by renewable energies as the final goal. This "Chemistry of Energy Conversion and Storage" issue contains papers dealing with the chemistry behind renewable energies. PMID:22407997

  9. Modeling of adsorption and bifunctional conversion of n-alkanes on Pt\\/H-ZSM-22 zeolite catalyst

    Microsoft Academic Search

    Joeri F. Denayer; Gino V. Baron; Gina Vanbutsele; Pierre A. Jacobs; Johan A. Martens

    1999-01-01

    The hydroconversion of C6C9 n-alkanes on Pt\\/H-ZSM-22 was investigated by measuring and modeling of the adsorption and catalytic properties of this strongly shape-selective zeolite catalyst. Henry adsorption constants and adsorption isotherms of C6C9 n- and iso-alkanes on H-ZSM-22 were determined with chromatographic techniques and fitted to different models. While n-alkanes have access to the internal pore structure of ZSM-22, only

  10. Alkane hydroxylases involved in microbial alkane degradation

    Microsoft Academic Search

    Jan B. van Beilen; Enrico G. Funhoff

    2007-01-01

    This review focuses on the role and distribution in the environment of alkane hydroxylases and their (potential) applications\\u000a in bioremediation and biocatalysis. Alkane hydroxylases play an important role in the microbial degradation of oil, chlorinated\\u000a hydrocarbons, fuel additives, and many other compounds. Environmental studies demonstrate the abundance of alkane degraders\\u000a and have lead to the identification of many new species,

  11. Contribution of chemistry to energy. [Fuels from coal; solar energy storage\\/conversion

    Microsoft Academic Search

    Cox

    1978-01-01

    Chemistry has contributed in many ways to energy production and conversion in the fossil fuel era. The challenges facing chemists and chemical engineers as we look forward to the 21st Century are addressed. This paper discusses some of the means that can be employed to meet this challenge both in the near-term and long-term, particularly alternate fuels from coal and

  12. Liquid phase thermochemical energy conversion systems - An application of Diels-Alder chemistry

    Microsoft Academic Search

    T. G. Lenz; L. S. Hegedus; J. D. Vaughan

    1982-01-01

    A method of thermochemical energy conversion, transport, and storage research involving moderate and low temperature liquid phase systems employing Diels-Alder cycloaddition chemistry is described. Proposed as a heat storage system for solar and industrial waste heat, the system involves the meeting, in a reactor, of energy-depleted and energy-rich fluids. The poor fluid gains energy and goes through a chemical, endothermic

  13. Conversion of Aldehyde to Alkane by a Peroxoiron(III) Complex: A Functional Model for the Cyanobacterial Aldehyde-Deformylating Oxygenase.

    PubMed

    Shokri, Alireza; Que, Lawrence

    2015-06-24

    Cyanobacterial aldehyde-deformylating oxygenase (cADO) converts long-chain fatty aldehydes to alkanes via a proposed diferric-peroxo intermediate that carries out the oxidative deformylation of the substrate. Herein, we report that the synthetic iron(III)-peroxo complex [Fe(III)(?(2)-O2)(TMC)](+) (TMC = tetramethylcyclam) causes a similar transformation in the presence of a suitable H atom donor, thus serving as a functional model for cADO. Mechanistic studies suggest that the H atom donor can intercept the incipient alkyl radical formed in the oxidative deformylation step in competition with the oxygen rebound step typically used by most oxygenases for forming C-O bonds. PMID:26030345

  14. Chemical Analog-to-Digital Signal Conversion Based on Robust Threshold Chemistry and Its Evaluation in the Context of

    E-print Network

    Ismagilov, Rustem F.

    Chemical Analog-to-Digital Signal Conversion Based on Robust Threshold Chemistry and Its Evaluation in the Context of Microfluidics-Based Quantitative Assays Toan Huynh, Bing Sun, Liang Li,, Kevin P. Nichols, Jay L. Koyner, and Rustem F. Ismagilov*, Department of Chemistry and Institute for Biophysical Dynamics

  15. The hydrodeoxygenation of bioderived furans into alkanes

    NASA Astrophysics Data System (ADS)

    Sutton, Andrew D.; Waldie, Fraser D.; Wu, Ruilian; Schlaf, Marcel; Pete' Silks, Louis A.; Gordon, John C.

    2013-05-01

    The conversion of biomass into fuels and chemical feedstocks is one part of a drive to reduce the world's dependence on crude oil. For transportation fuels in particular, wholesale replacement of a fuel is logistically problematic, not least because of the infrastructure that is already in place. Here, we describe the catalytic defunctionalization of a series of biomass-derived molecules to provide linear alkanes suitable for use as transportation fuels. These biomass-derived molecules contain a variety of functional groups, including olefins, furan rings and carbonyl groups. We describe the removal of these in either a stepwise process or a one-pot process using common reagents and catalysts under mild reaction conditions to provide n-alkanes in good yields and with high selectivities. Our general synthetic approach is applicable to a range of precursors with different carbon content (chain length). This allows the selective generation of linear alkanes with carbon chain lengths between eight and sixteen carbons.

  16. Cation-alkane interaction.

    PubMed

    Premkumar, J Richard; Sastry, G Narahari

    2014-12-01

    Ab initio computations, up to CCSD(T)/CBS on model systems, and MP2/cc-pVTZ and DFT calculations are performed on cation-alkane and cation-alkene complexes, cation = Li(+), Na(+), Be(2+), Mg(2+), Ca(2+), Cu(+) and Zn(2+); alkane = C(n)H2(n+2) (n = 1-10) and C6H12; and alkene = C2H4 and C6H6. Density functional theory-symmetry adapted perturbation theory (DFT-SAPT) calculations reveal that the cation-alkane interactions are predominantly constituted of induction component. The dramatic modulation of the strength of their interaction and the topological features obtained from atoms in molecules (AIM) analysis are consistent with the characteristics of a typical noncovalent interaction. In contrast to many of the conventional noncovalent interactions, cation-alkane interactions are substantially strong and are comparable in strength to the well studied cation-? interactions. PMID:25384257

  17. Gas-to-Particle Conversion in Surface Discharge Nonthermal Plasmas and Its Implications for Atmospheric Chemistry

    PubMed Central

    Kim, Hyun-Ha; Ogata, Atsushi

    2011-01-01

    This paper presents some experimental data on gas-to-particle conversion of benzene using nonthermal plasma (NTP) technology and discusses the possibility of its technical application in atmospheric chemistry. Aerosol measurement using a differential mobility analyzer (DMA) revealed that the parts of benzene molecules were converted into a nanometer-sized aerosol. Aerosol formation was found to be highly related with the missing part in carbon balance. Scanning electron microscopy analysis showed that the aerosols formed in synthetic humid air are the collection of nanoparticles. The carbonyl band (C=O) was found to be an important chemical constituent in the aerosol. The potential of the NTP as an accelerated test tool in studying secondary organic aerosol (SOA) formation from VOCs will be also addressed. PMID:22163781

  18. Modelling chemistry in aircraft plumes 2: the chemical conversion of NO x to reservoir species under different conditions

    Microsoft Academic Search

    Anne Gunn Kraabl; Frode Stordal

    2000-01-01

    An expanding plume model with chemistry has been used to study the chemical conversion of nitrogen oxides to reservoir species in aircraft plumes under various conditions. A plume from a B747 was studied, where the NOx emission index was 26.1gkg?1. Several sensitivity tests were performed for emissions at 07 UT at 50N under summer conditions. The amount of NOx remaining

  19. Drugs in the Chemistry Laboratory: The Conversion of Acetaminophen into Phenacetin.

    ERIC Educational Resources Information Center

    Volker, Eugene J.; And Others

    1979-01-01

    Describes an experiment in which acetaminophen is converted into phenacetin, that has been used at Shepherd College in an introductory chemistry course for nurses and in the organic chemistry laboratory. (BT)

  20. Wetting of alkanes on water

    Microsoft Academic Search

    E. Bertrand; D. Bonn; D. Broseta; H. Dobbs; J. O. Indekeu; J. Meunier; K. Ragil; N. Shahidzadeh

    2002-01-01

    The wetting behavior of oil on water (or brine) has important consequences for the transport properties of oil in water-containing porous reservoirs, and consequently for oil recovery. The equilibrium wetting behavior of model oils composed of pure alkanes or alkane mixtures on brine is reviewed in this paper. Intermediate between the partial wetting state, in which oil lenses coexist on

  1. Catalytic, mild, and selective oxyfunctionalization of linear alkanes: current challenges.

    PubMed

    Bordeaux, Mlanie; Galarneau, Anne; Drone, Jullien

    2012-10-22

    Selective catalysts for sustainable oxidation of alkanes are highly demanded because of the abundance of these molecules in the environment, the possibility to transform them into higher-value compounds, such as chemicals or synthetic fuels, and the fact that, kinetically speaking, this is a difficult reaction. Numerous chemical and biological catalysts have been developed in the lasts decades for this purpose, rendering the overview over this field of chemistry difficult. After giving a definition of the ideal catalyst for alkane oxyfunctionalization, this review aims to present the catalysts available today that are closest to ideal. PMID:22996726

  2. High Temperature Chemical Kinetic Combustion Modeling of Lightly Methylated Alkanes

    SciTech Connect

    Sarathy, S M; Westbrook, C K; Pitz, W J; Mehl, M

    2011-03-01

    Conventional petroleum jet and diesel fuels, as well as alternative Fischer-Tropsch (FT) fuels and hydrotreated renewable jet (HRJ) fuels, contain high molecular weight lightly branched alkanes (i.e., methylalkanes) and straight chain alkanes (n-alkanes). Improving the combustion of these fuels in practical applications requires a fundamental understanding of large hydrocarbon combustion chemistry. This research project presents a detailed high temperature chemical kinetic mechanism for n-octane and three lightly branched isomers octane (i.e., 2-methylheptane, 3-methylheptane, and 2,5-dimethylhexane). The model is validated against experimental data from a variety of fundamental combustion devices. This new model is used to show how the location and number of methyl branches affects fuel reactivity including laminar flame speed and species formation.

  3. Conversion of CO2 to Polycarbonates and Other Materials: Insights through Computational Chemistry

    E-print Network

    Yeung, Andrew D

    2014-09-25

    The use of carbon dioxide as a chemical feedstock for the copolymerization with epoxides to give polycarbonates, and for coupling with hydrocarbons to give carboxylic acids, was probed using computational chemistry. Metal-free systems were modeled...

  4. Multi-scale chemistry modeling of the thermochemical conversion of biomass in a fluidized bed gasifier

    E-print Network

    Stark, Addison Killean

    2015-01-01

    The thermochemical conversion of biomass to fuels via syn-gas offers a promising approach to producing fungible substitutes for petroleum derived fuels and chemicals. In order for these fuels to be adopted, they must be ...

  5. Rubredoxins Involved in Alkane Oxidation

    PubMed Central

    van Beilen, Jan B.; Neuenschwander, Martin; Smits, Theo H. M.; Roth, Christian; Balada, Stefanie B.; Witholt, Bernard

    2002-01-01

    Rubredoxins (Rds) are essential electron transfer components of bacterial membrane-bound alkane hydroxylase systems. Several Rd genes associated with alkane hydroxylase or Rd reductase genes were cloned from gram-positive and gram-negative organisms able to grow on n-alkanes (Alk-Rds). Complementation tests in an Escherichia coli recombinant containing all Pseudomonas putida GPo1 genes necessary for growth on alkanes except Rd 2 (AlkG) and sequence comparisons showed that the Alk-Rds can be divided in AlkG1- and AlkG2-type Rds. All alkane-degrading strains contain AlkG2-type Rds, which are able to replace the GPo1 Rd 2 in n-octane hydroxylation. Most strains also contain AlkG1-type Rds, which do not complement the deletion mutant but are highly conserved among gram-positive and gram-negative bacteria. Common to most Rds are the two iron-binding CXXCG motifs. All Alk-Rds possess four negatively charged residues that are not conserved in other Rds. The AlkG1-type Rds can be distinguished from the AlkG2-type Rds by the insertion of an arginine downstream of the second CXXCG motif. In addition, the glycines in the two CXXCG motifs are usually replaced by other amino acids. Mutagenesis of residues conserved in either the AlkG1- or the AlkG2-type Rds, but not between both types, shows that AlkG1 is unable to transfer electrons to the alkane hydroxylase mainly due to the insertion of the arginine, whereas the exchange of the glycines in the two CXXCG motifs only has a limited effect. PMID:11872724

  6. Nanoparticles as Reactive Precursors: Synthesis of Alloys, Intermetallic Compounds, and Multi-Metal Oxides Through Low-Temperature Annealing and Conversion Chemistry

    E-print Network

    Bauer, John C.

    2010-07-14

    for formic acid oxidation while Pt3Sn/Vulcan XC-72 and Cu3Pt/y-Al2O3 catalyzed CO oxidiation at lower temperatures than supported Pt. Intermetallic nanoparticles of Pd were synthesized by conversion chemistry methods previously mentioned and were supported...

  7. Chemistry

    NSDL National Science Digital Library

    K-12 Outreach,

    Chemistry is the scientific study of matter and its interaction with other matter and with energy. It is the branch of natural science that deals with the composition of substances and their properties and reactions.

  8. Alkane C-h functionalization and oxidation with molecular oxygen.

    PubMed

    Munz, Dominik; Strassner, Thomas

    2015-06-01

    The application of environmentally benign, cheap, and economically viable oxidation procedures is a key challenge of homogeneous, oxidative alkane functionalization. The typically harsh reaction conditions and the propensity of dioxygen for radical reactivity call for extraordinary robust catalysts. Mainly three strategies have been applied. These are (1) the combination of a catalyst responsible for C-H activation with a cocatalyst responsible for dioxygen activation, (2) transition-metal catalysts, which react with both hydrocarbons and molecular oxygen, and (3) the introduction of very robust main-group element catalysts for C-H functionalization chemistry. Herein, these three approaches will be assessed and exemplified by the reactivity of chelated palladium (N-heterocyclic carbene) catalysts in combination with a vanadium cocatalyst, the methane functionalization by cobalt catalysts, and the reaction of group XVII compounds with alkanes. PMID:25822853

  9. Characterization of a novel long-chain n-alkane-degrading strain, Dietzia sp. E1.

    PubMed

    Bihari, Zoltn; Szab, Zsolt; Szvetnik, Attila; Balzs, Margit; Bartos, Pter; Tolmacsov, Pter; Zombori, Zoltn; Kiss, Istvn

    2010-01-01

    The newly isolated strain E1, identified as a Dietzia sp., proved to have an excellent ability to degrade n-C12 to n-C38 alkane components of crude oil. The preferred substrate was the very long-chain alkane n-eicosane at an optimal temperature of 37 degrees C and an optimal pH of 8 under aerobic conditions. The growth and substrate uptake kinetics were monitored during the n-alkane fermentation process, and Dietzia sp. E1 cells were found to possess three distinct levels of cell-surface hydrophobicity. Gas chromatographic/mass spectrometric analysis revealed that intracellular substrate mineralization occurred through the conversion of n-alkane to the corresponding n-alkanal. The monoterminal oxidation pathway was presumably initiated by AlkB and CYP153 terminal alkane hydroxylases, both of their partial coding sequences were successfully detected in the genome of strain E1, a novel member of the Dietzia genus. PMID:21319712

  10. Modeling SOA production from the oxidation of intermediate volatility alkanes

    NASA Astrophysics Data System (ADS)

    Aumont, B.; Mouchel-Vallon, C.; Camredon, M.; Lee-Taylor, J.; Madronich, S.

    2012-12-01

    Secondary Organic Aerosols (SOA) production and ageing is a multigenerational oxidation process involving the formation of successive organic compounds with higher oxidation degree and lower vapour pressure. This process was investigated using the explicit oxidation model GECKO-A (Generator for Explicit Chemistry and Kinetics of Organics in the Atmosphere). Results for the C8-C24 n-alkane series show the expected trends, i.e. (i) SOA yield grows with the carbon backbone of the parent hydrocarbon, (ii) SOA yields decreases with the decreasing pre-existing organic aerosol concentration, (iii) the number of generations required to describe SOA production increases when the pre-existing organic aerosol concentration decreases. Most SOA contributors were found to be not oxidized enough to be categorized as highly oxygenated organic aerosols (OOA) but reduced enough to be categorized as hydrocarbon like organic aerosols (HOA). Branched alkanes are more prone to fragment in the early stage of the oxidation than their corresponding linear analogues. Fragmentation is expected to alter both the yield and the mean oxidation state of the SOA. Here, GECKO-A is applied to generate highly detailed oxidation schemes for various series of branched and cyclised alkanes. Branching and cyclisation effects on SOA yields and oxidation states will be examined.

  11. 40 CFR 721.536 - Halogenated phenyl alkane.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 2013-07-01 false Halogenated phenyl alkane. 721.536 Section 721.536...Substances 721.536 Halogenated phenyl alkane. (a) Chemical substance and...substance identified generically as halogenated phenyl alkane (PMN P-89-867) is...

  12. 40 CFR 721.536 - Halogenated phenyl alkane.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 2014-07-01 false Halogenated phenyl alkane. 721.536 Section 721.536...Substances 721.536 Halogenated phenyl alkane. (a) Chemical substance and...substance identified generically as halogenated phenyl alkane (PMN P-89-867) is...

  13. 40 CFR 721.536 - Halogenated phenyl alkane.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 2011-07-01 false Halogenated phenyl alkane. 721.536 Section 721.536...Substances 721.536 Halogenated phenyl alkane. (a) Chemical substance and...substance identified generically as halogenated phenyl alkane (PMN P-89-867) is...

  14. 40 CFR 721.536 - Halogenated phenyl alkane.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 2012-07-01 false Halogenated phenyl alkane. 721.536 Section 721.536...Substances 721.536 Halogenated phenyl alkane. (a) Chemical substance and...substance identified generically as halogenated phenyl alkane (PMN P-89-867) is...

  15. 40 CFR 721.536 - Halogenated phenyl alkane.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 2010-07-01 false Halogenated phenyl alkane. 721.536 Section 721.536...Substances 721.536 Halogenated phenyl alkane. (a) Chemical substance and...substance identified generically as halogenated phenyl alkane (PMN P-89-867) is...

  16. Alkane activation on crystalline metal oxide surfaces.

    PubMed

    Weaver, Jason F; Hakanoglu, Can; Antony, Abbin; Asthagiri, Aravind

    2014-11-21

    Advances in the fundamental understanding of alkane activation on oxide surfaces are essential for developing new catalysts that efficiently and selectively promote chemical transformations of alkanes. In this tutorial review, we discuss the current understanding of alkane activation on crystalline metal oxide surfaces, and focus mainly on summarizing our findings on alkane adsorption and C-H bond cleavage on the PdO(101) surface as determined from model ultrahigh vacuum experiments and theoretical calculations. These studies show that alkanes form strongly-bound ?-complexes on PdO(101) by datively bonding with coordinatively-unsaturated Pd atoms and that these molecularly adsorbed species serve as precursors for C-H bond activation on the oxide surface. In addition to discussing the binding and properties of alkane ?-complexes on PdO(101), we also summarize recent advances in kinetic models to predict alkane dissociation rates on solid surfaces. Lastly, we highlight computations which predict that the formation and facile C-H bond activation of alkane ?-complexes also occurs on RuO2 and IrO2 surfaces. PMID:24480977

  17. Transcriptome response to alkane biofuels in Saccharomyces cerevisiae: identification of efflux pumps involved in alkane tolerance

    PubMed Central

    2013-01-01

    Background Hydrocarbon alkanes have been recently considered as important next-generation biofuels because microbial production of alkane biofuels was demonstrated. However, the toxicity of alkanes to microbial hosts can possibly be a bottleneck for high productivity of alkane biofuels. To tackle this toxicity issue, it is essential to understand molecular mechanisms of interactions between alkanes and microbial hosts, and to harness these mechanisms to develop microbial host strains with improved tolerance against alkanes. In this study, we aimed to improve the tolerance of Saccharomyces cerevisiae, a model eukaryotic host of industrial significance, to alkane biofuels by exploiting cellular mechanisms underlying alkane response. Results To this end, we first confirmed that nonane (C9), decane (C10), and undecane (C11) were significantly toxic and accumulated in S. cerevisiae. Transcriptome analyses suggested that C9 and C10 induced a range of cellular mechanisms such as efflux pumps, membrane modification, radical detoxification, and energy supply. Since efflux pumps could possibly aid in alkane secretion, thereby reducing the cytotoxicity, we formed the hypothesis that those induced efflux pumps could contribute to alkane export and tolerance. In support of this hypothesis, we demonstrated the roles of the efflux pumps Snq2p and Pdr5p in reducing intracellular levels of C10 and C11, as well as enhancing tolerance levels against C10 and C11. This result provided the evidence that Snq2p and Pdr5p were associated with alkane export and tolerance in S. cerevisiae. Conclusions Here, we investigated the cellular mechanisms of S. cerevisiae response to alkane biofuels at a systems level through transcriptome analyses. Based on these mechanisms, we identified efflux pumps involved in alkane export and tolerance in S. cerevisiae. We believe that the results here provide valuable insights into designing microbial engineering strategies to improve cellular tolerance for highly efficient alkane biofuel production. PMID:23826995

  18. The anaerobic degradation of gaseous, nonmethane alkanes - From in situ processes to microorganisms.

    PubMed

    Musat, Florin

    2015-01-01

    The short chain, gaseous alkanes ethane, propane, n- and iso-butane are released in significant amounts into the atmosphere, where they contribute to tropospheric chemistry and ozone formation. Biodegradation of gaseous alkanes by aerobic microorganisms, mostly bacteria and fungi isolated from terrestrial environments, has been known for several decades. The first indications for short chain alkane anaerobic degradation were provided by geochemical studies of deep-sea environments around hydrocarbon seeps, and included the uncoupling of the sulfate-reduction and anaerobic oxidation of methane rates, the consumption of gaseous alkanes in anoxic sediments, or the enrichment in (13)C of gases in interstitial water vs. the source gas. Microorganisms able to degrade gaseous alkanes were recently obtained from deep-sea and terrestrial sediments around hydrocarbon seeps. Up to date, only sulfate-reducing pure or enriched cultures with ethane, propane and n-butane have been reported. The only pure culture presently available, strain BuS5, is affiliated to the Desulfosarcina-Desulfococcus cluster of the Deltaproteobacteria. Other phylotypes involved in gaseous alkane degradation have been identified based on stable-isotope labeling and whole-cell hybridization. Under anoxic conditions, propane and n-butane are activated similar to the higher alkanes, by homolytic cleavage of the C-H bond of a subterminal carbon atom, and addition of the ensuing radical to fumarate, yielding methylalkylsuccinates. An additional mechanism of activation at the terminal carbon atoms was demonstrated for propane, which could in principle be employed also for the activation of ethane. PMID:25904994

  19. Molecular and Thermal Diffusion Coefficients of Alkane-Alkane and Alkane-Aromatic Binary Mixtures: Effect of Shape and Size of Molecules

    E-print Network

    Firoozabadi, Abbas

    Molecular and Thermal Diffusion Coefficients of Alkane-Alkane and Alkane-Aromatic Binary Mixtures Form: October 27, 2006 New molecular and thermal diffusion coefficients of binary mixtures of normal-molecular diffusion coefficient for nC10 from binary data. I. Introduction Molecular and thermal diffusion processes

  20. Dielectric barrier discharges used for the conversion of greenhouse gases: modeling the plasma chemistry by fluid simulations

    NASA Astrophysics Data System (ADS)

    De Bie, Christophe; Martens, Tom; van Dijk, Jan; Paulussen, Sabine; Verheyde, Bert; Corthals, Steven; Bogaerts, Annemie

    2011-04-01

    The conversion of methane to value-added chemicals and fuels is considered to be one of the challenges of the 21st century. In this paper we study, by means of fluid modeling, the conversion of methane to higher hydrocarbons or oxygenates by partial oxidation with CO2 or O2 in a dielectric barrier discharge. Sixty-nine different plasma species (electrons, ions, molecules, radicals) are included in the model, as well as a comprehensive set of chemical reactions. The calculation results presented in this paper include the conversion of the reactants and the yields of the reaction products as a function of residence time in the reactor, for different gas mixing ratios. Syngas (i.e. H2 + CO) and higher hydrocarbons (C2Hx) are typically found to be important reaction products.

  1. Hydroconversion of long-chain n-alkanes on Pt\\/HZSM-5 zeolite

    Microsoft Academic Search

    J. Weitkamp; P. A. Jacobs

    1983-01-01

    A study was made of the isomerization and hydrocracking of long-chain n-alkanes (C to C). A Pt\\/HZSM-5 zeolite catalyst with a Si\\/Al ratio of 60 and 5 wt % of platinum was used in a fixed bed reactor with a 2 MPa pressure in a hydrogen atmosphere. In the temperature range of 200 to 280°C and conversions up to 90%,

  2. Intra-Catalyst Reductant Chemistry and NOx Conversion of Diesel Lean NOx Traps at Various Stages of Sulfur Loading

    SciTech Connect

    Parks, II, James E [ORNL; Swartz, Matthew M [ORNL; Huff, Shean P [ORNL; West, Brian H [ORNL

    2006-01-01

    Due to increasingly stringent emissions regulations, Lean NOX Trap (LNT) catalysts are being researched as a potential solution for diesel engine emissions reduction. LNTs are practical for diesel NOX reduction due to their ability to reduce NOX from the O2 rich environment produced by diesel engines. LNTs function by storing NOX on the catalyst surface during efficient lean operation then, under rich conditions, releasing and reducing the trapped NOX. One method of producing this rich environment which regenerates a LNT involves manipulating the fuel injection parameters and throttling the air intake. This process is called in-cylinder regeneration. Experiments will be described here in which a 1.7 L common rail diesel engine has been used to regenerate LNTs at various stages of sulfur exposure, a known poison of the LNT. In-cylinder regeneration strategies were used to produce a range of reductant chemistries which enabled the study of the role of various reductants as NOX was converted across the LNT. This study gives insight into how to most efficiently regenerate the LNT. Sulfur poisoning of a fresh LNT was accelerated via the use of bottled SO2. Regeneration studies at various states of sulfation and after catalyst desulfation are discussed, highlighting intra-catalyst measurements of reductant chemistry and NOX conversion through the catalyst. Results showed that as sulfur loading increased, NOX conversion efficiency decreased and reductant utilization shifted downstream. Hydrogen from in-cylinder combustion was consumed over the first half of the LNT then produced from other available reductants over the last half for some strategies and conditions. Hydrogen production over the last portion of the catalyst was found to be affected by sulfur.

  3. Cool-flame Extinction During N-Alkane Droplet Combustion in Microgravity

    NASA Technical Reports Server (NTRS)

    Nayagam, Vedha; Dietrich, Daniel L.; Hicks, Michael C.; Williams, Forman A.

    2014-01-01

    Recent droplet combustion experiments onboard the International Space Station (ISS) have revealed that large n-alkane droplets can continue to burn quasi-steadily following radiative extinction in a low-temperature regime, characterized by negative-temperaturecoefficient (NTC) chemistry. In this study we report experimental observations of n-heptane, n-octane, and n-decane droplets of varying initial sizes burning in oxygen/nitrogen/carbon dioxide and oxygen/helium/nitrogen environments at 1.0, 0.7, and 0.5 atmospheric pressures. The oxygen concentration in these tests varied in the range of 14% to 25% by volume. Large n-alkane droplets exhibited quasi-steady low-temperature burning and extinction following radiative extinction of the visible flame while smaller droplets burned to completion or disruptively extinguished. A vapor-cloud formed in most cases slightly prior to or following the "cool flame" extinction. Results for droplet burning rates in both the hot-flame and cool-flame regimes as well as droplet extinction diameters at the end of each stage are presented. Time histories of radiant emission from the droplet captured using broadband radiometers are also presented. Remarkably the "cool flame" extinction diameters for all the three n-alkanes follow a trend reminiscent of the ignition delay times observed in previous studies. The similarities and differences among the n-alkanes during "cool flame" combustion are discussed using simplified theoretical models of the phenomenon

  4. Microbial production of short-chain alkanes.

    PubMed

    Choi, Yong Jun; Lee, Sang Yup

    2013-10-24

    Increasing concerns about limited fossil fuels and global environmental problems have focused attention on the need to develop sustainable biofuels from renewable resources. Although microbial production of diesel has been reported, production of another much in demand transport fuel, petrol (gasoline), has not yet been demonstrated. Here we report the development of platform Escherichia coli strains that are capable of producing short-chain alkanes (SCAs; petrol), free fatty acids (FFAs), fatty esters and fatty alcohols through the fatty acyl (acyl carrier protein (ACP)) to fatty acid to fatty acyl-CoA pathway. First, the ?-oxidation pathway was blocked by deleting the fadE gene to prevent the degradation of fatty acyl-CoAs generated in vivo. To increase the formation of short-chain fatty acids suitable for subsequent conversion to SCAs in vivo, the activity of 3-oxoacyl-ACP synthase (FabH), which is inhibited by unsaturated fatty acyl-ACPs, was enhanced to promote the initiation of fatty acid biosynthesis by deleting the fadR gene; deletion of the fadR gene prevents upregulation of the fabA and fabB genes responsible for unsaturated fatty acids biosynthesis. A modified thioesterase was used to convert short-chain fatty acyl-ACPs to the corresponding FFAs, which were then converted to SCAs by the sequential reactions of E. coli fatty acyl-CoA synthetase, Clostridium acetobutylicum fatty acyl-CoA reductase and Arabidopsis thaliana fatty aldehyde decarbonylase. The final engineered strain produced up to 580.8?mg?l(-1) of SCAs consisting of nonane (327.8?mg?l(-1)), dodecane (136.5?mg?l(-1)), tridecane (64.8?mg?l(-1)), 2-methyl-dodecane (42.8?mg?l(-1)) and tetradecane (8.9?mg?l(-1)), together with small amounts of other hydrocarbons. Furthermore, this platform strain could produce short-chain FFAs using a fadD-deleted strain, and short-chain fatty esters by introducing the Acinetobacter sp. ADP1 wax ester synthase (atfA) and the E. coli mutant alcohol dehydrogenase (adhE(mut)). PMID:24077097

  5. Improved Alkane Production in Nitrogen-Fixing and Halotolerant Cyanobacteria via Abiotic Stresses and Genetic Manipulation of Alkane Synthetic Genes.

    PubMed

    Kageyama, Hakuto; Waditee-Sirisattha, Rungaroon; Sirisattha, Sophon; Tanaka, Yoshito; Mahakhant, Aparat; Takabe, Teruhiro

    2015-07-01

    Cyanobacteria possess the unique capacity to produce alkane. In this study, effects of nitrogen deficiency and salt stress on biosynthesis of alkanes were investigated in three kinds of cyanobacteria. Intracellular alkane accumulation was increased in nitrogen-fixing cyanobacterium Anabaena sp. PCC7120, but decreased in non-diazotrophic cyanobacterium Synechococcus elongatus PCC7942 and constant in a halotolerant cyanobacterium Aphanothece halophytica under nitrogen-deficient condition. We also found that salt stress increased alkane accumulation in Anabaena sp. PCC7120 and A. halophytica. The expression levels of two alkane synthetic genes were not upregulated significantly under nitrogen deficiency or salt stress in Anabaena sp. PCC7120. The transformant Anabaena sp. PCC7120 cells with additional alkane synthetic gene set from A. halophytica increased intracellular alkane accumulation level compared to control cells. These results provide a prospect to improve bioproduction of alkanes in nitrogen-fixing halotolerant cyanobacteria via abiotic stresses and genetic engineering. PMID:25971893

  6. In situ detection of anaerobic alkane metabolites in subsurface environments.

    PubMed

    Agrawal, Akhil; Gieg, Lisa M

    2013-01-01

    Alkanes comprise a substantial fraction of crude oil and refined fuels. As such, they are prevalent within deep subsurface fossil fuel deposits and in shallow subsurface environments such as aquifers that are contaminated with hydrocarbons. These environments are typically anaerobic, and host diverse microbial communities that can potentially use alkanes as substrates. Anaerobic alkane biodegradation has been reported to occur under nitrate-reducing, sulfate-reducing, and methanogenic conditions. Elucidating the pathways of anaerobic alkane metabolism has been of interest in order to understand how microbes can be used to remediate contaminated sites. Alkane activation primarily occurs by addition to fumarate, yielding alkylsuccinates, unique anaerobic metabolites that can be used to indicate in situ anaerobic alkane metabolism. These metabolites have been detected in hydrocarbon-contaminated shallow aquifers, offering strong evidence for intrinsic anaerobic bioremediation. Recently, studies have also revealed that alkylsuccinates are present in oil and coal seam production waters, indicating that anaerobic microbial communities can utilize alkanes in these deeper subsurface environments. In many crude oil reservoirs, the in situ anaerobic metabolism of hydrocarbons such as alkanes may be contributing to modern-day detrimental effects such as oilfield souring, or may lead to more beneficial technologies such as enhanced energy recovery from mature oilfields. In this review, we briefly describe the key metabolic pathways for anaerobic alkane (including n-alkanes, isoalkanes, and cyclic alkanes) metabolism and highlight several field reports wherein alkylsuccinates have provided evidence for anaerobic in situ alkane metabolism in shallow and deep subsurface environments. PMID:23761789

  7. Pervaporation separation of alkane\\/thiophene mixtures with PDMS membrane

    Microsoft Academic Search

    Rongbin Qi; Yujun Wang; Jiding Li; Changwei Zhao; Shenlin Zhu

    2006-01-01

    Worldwide concerns over environment have stimulated increasing interest both in academic and industry for deep desulfurization of gasoline. Polydimethylsiloxane (PDMS) composite membrane was used to separate the binary and multicomponent alkane\\/thiophene mixtures by pervaporation. Effect of carbon number and concentration of alkane, and of feed temperature, on the separation efficiency of alkane\\/thiophene mixtures was investigated experimentally. Experimental results of binary

  8. Interrogation of Chesapeake Bay sediment microbial communities for intrinsic alkane-utilizing potential under anaerobic conditions.

    PubMed

    Johnson, Jamie M; Wawrik, Boris; Isom, Catherine; Boling, Wilford B; Callaghan, Amy V

    2015-02-01

    Based on the transient exposure of Chesapeake Bay sediments to hydrocarbons and the metabolic versatility of known anaerobic alkane-degrading microorganisms, it was hypothesized that distinct Bay sediment communities, governed by geochemical gradients, would have intrinsic alkane-utilizing potential under sulfate-reducing and/or methanogenic conditions. Sediment cores were collected along a transect of the Bay. Community DNA was interrogated via pyrosequencing of 16S rRNA genes, PCR of anaerobic hydrocarbon activation genes, and qPCR of 16S rRNA genes and genes involved in sulfate reduction/methanogenesis. Site sediments were used to establish microcosms amended with n-hexadecane under sulfate-reducing and methanogenic conditions. Sequencing of 16S rRNA genes indicated that sediments associated with hypoxic water columns contained significantly greater proportions of Bacteria and Archaea consistent with syntrophic degradation of organic matter and methanogenesis compared to less reduced sediments. Microbial taxa frequently associated with hydrocarbon-degrading communities were found throughout the Bay, and the genetic potential for hydrocarbon metabolism was demonstrated via the detection of benzyl-(bssA) and alkylsuccinate synthase (assA) genes. Although microcosm studies did not indicate sulfidogenic alkane degradation, the data suggested that methanogenic conversion of alkanes was occurring. These findings highlight the potential role that anaerobic microorganisms could play in the bioremediation of hydrocarbons in the Bay. PMID:25764556

  9. Alkanes and alkenes in marine benthic algae

    Microsoft Academic Search

    W. W. Youngblood; M. Blumer

    1973-01-01

    Saturated and olefinic hydrocarbons were determined in additional species of benthic marine algae from the Cape Cod (Massachusetts, USA) area (see: Youngblood et al., 1971). The distribution of homologous and isomeric olefins was studied in plants of different age and in morphologically different parts of the same specimen. With two minor exceptions, only normal alkanes and alkenes are present. The

  10. Reflectance spectroscopy of organic compounds: 1. Alkanes

    USGS Publications Warehouse

    Clark, R.N.; Curchin, J.M.; Hoefen, T.M.; Swayze, G.A.

    2009-01-01

    Reflectance spectra of the organic compounds comprising the alkane series are presented from the ultraviolet to midinfrared, 0.35 to 15.5 /??m. Alkanes are hydrocarbon molecules containing only single carbon-carbon bonds, and are found naturally on the Earth and in the atmospheres of the giant planets and Saturn's moon, Titan. This paper presents the spectral properties of the alkanes as the first in a series of papers to build a spectral database of organic compounds for use in remote sensing studies. Applications range from mapping the environment on the Earth, to the search for organic molecules and life in the solar system and throughout the. universe. We show that the spectral reflectance properties of organic compounds are rich, with major diagnostic spectral features throughout the spectral range studied. Little to no spectral change was observed as a function of temperature and only small shifts and changes in the width of absorption bands were observed between liquids and solids, making remote detection of spectral properties throughout the solar system simpler. Some high molecular weight organic compounds contain single-bonded carbon chains and have spectra similar to alkanes even ' when they fall into other families. Small spectral differences are often present allowing discrimination among some compounds, further illustrating the need to catalog spectral properties for accurate remote sensing identification with spectroscopy.

  11. Comprehensive chemical kinetic modeling of the oxidation of C8 and larger n-alkanes and 2-methylalkanes

    SciTech Connect

    Sarathy, S M; Westbrook, C K; Pitz, W J; Mehl, M; Togbe, C; Dagaut, P; Wang, H; Oehlschlaeger, M; NIemann, U; Seshadri, K; Veloo, P S; Ji, C; Egolfopoulos, F; Lu, T

    2011-03-16

    Conventional petroleum jet and diesel fuels, as well as alternative Fischer-Tropsch (FT) fuels and hydrotreated renewable jet (HRJ) fuels, contain high molecular weight lightly branched alkanes (i.e., methylalkanes) and straight chain alkanes (n-alkanes). Improving the combustion of these fuels in practical applications requires a fundamental understanding of large hydrocarbon combustion chemistry. This research project presents a detailed and reduced chemical kinetic mechanism for singly methylated iso-alkanes (i.e., 2-methylalkanes) ranging from C{sub 8} to C{sub 20}. The mechanism also includes an updated version of our previously published C{sub 8} to C{sub 16} n-alkanes model. The complete detailed mechanism contains approximately 7,200 species 31,400 reactions. The proposed model is validated against new experimental data from a variety of fundamental combustion devices including premixed and nonpremixed flames, perfectly stirred reactors and shock tubes. This new model is used to show how the presence of a methyl branch affects important combustion properties such as laminar flame propagation, ignition, and species formation.

  12. Modeling of Alkane Oxidation Using Constituents and Species

    NASA Technical Reports Server (NTRS)

    Bellan, Jasette; Harstad, Kenneth G.

    2010-01-01

    It is currently not possible to perform simulations of turbulent reactive flows due in particular to complex chemistry, which may contain thousands of reactions and hundreds of species. This complex chemistry results in additional differential equations, making the numerical solution of the equation set computationally prohibitive. Reducing the chemical kinetics mathematical description is one of several important goals in turbulent reactive flow modeling. A chemical kinetics reduction model is proposed for alkane oxidation in air that is based on a parallel methodology to that used in turbulence modeling in the context of the Large Eddy Simulation. The objective of kinetic modeling is to predict the heat release and temperature evolution. This kinetic mechanism is valid over a pressure range from atmospheric to 60 bar, temperatures from 600 K to 2,500 K, and equivalence ratios from 0.125 to 8. This range encompasses diesel, HCCI, and gas-turbine engines, including cold ignition. A computationally efficient kinetic reduction has been proposed for alkanes that has been illustrated for n-heptane using the LLNL heptane mechanism. This model is consistent with turbulence modeling in that scales were first categorized into either those modeled or those computed as progress variables. Species were identified as being either light or heavy. The heavy species were decomposed into defined 13 constituents, and their total molar density was shown to evolve in a quasi-steady manner. The light species behave either in a quasi-steady or unsteady manner. The modeled scales are the total constituent molar density, Nc, and the molar density of the quasi-steady light species. The progress variables are the total constituent molar density rate evolution and the molar densities of the unsteady light species. The unsteady equations for the light species contain contributions of the type gain/loss rates from the heavy species that are modeled consistent with the developed mathematical forms for the total constituent molar density rate evolution; indeed, examination of these gain/loss rates shows that they also have a good quasi-steady behavior with a functional form resembling that of the constituent rate. This finding highlights the fact that the fitting technique provides a methodology that can be repeatedly used to obtain an accurate representation of full or skeletal kinetic models. Assuming success with the modified reduced model, the advantage of the modeling approach is clear. Because this model is based on the Nc rate rather than on that of individual heavy species, even if the number of species increases with increased carbon number in the alkane group, providing that the quasi-steady rate aspect persists, then extension of this model to higher alkanes should be conceptually straightforward, although it remains to be seen if the functional fits would remain valid or would require reconstruction.

  13. Overcoming lability of extremely long alkane carbon-carbon bonds through dispersion forces.

    PubMed

    Schreiner, Peter R; Chernish, Lesya V; Gunchenko, Pavel A; Tikhonchuk, Evgeniya Yu; Hausmann, Heike; Serafin, Michael; Schlecht, Sabine; Dahl, Jeremy E P; Carlson, Robert M K; Fokin, Andrey A

    2011-09-15

    Steric effects in chemistry are a consequence of the space required to accommodate the atoms and groups within a molecule, and are often thought to be dominated by repulsive forces arising from overlapping electron densities (Pauli repulsion). An appreciation of attractive interactions such as van der Waals forces (which include London dispersion forces) is necessary to understand chemical bonding and reactivity fully. This is evident from, for example, the strongly debated origin of the higher stability of branched alkanes relative to linear alkanes and the possibility of constructing hydrocarbons with extraordinarily long C-C single bonds through steric crowding. Although empirical bond distance/bond strength relationships have been established for C-C bonds (longer C-C bonds have smaller bond dissociation energies), these have no present theoretical basis. Nevertheless, these empirical considerations are fundamental to structural and energetic evaluations in chemistry, as summarized by Pauling as early as 1960 and confirmed more recently. Here we report the preparation of hydrocarbons with extremely long C-C bonds (up to 1.704?), the longest such bonds observed so far in alkanes. The prepared compounds are unexpectedly stable--noticeable decomposition occurs only above 200?C. We prepared the alkanes by coupling nanometre-sized, diamond-like, highly rigid structures known as diamondoids. The extraordinary stability of the coupling products is due to overall attractive dispersion interactions between the intramolecular HH contact surfaces, as is evident from density functional theory computations with and without inclusion of dispersion corrections. PMID:21921913

  14. Oxidation of Alkyl-substituted Cyclic Hydrocarbons by a Nocardia during Growth on n-Alkanes

    PubMed Central

    Davis, J. B.; Raymond, R. L.

    1961-01-01

    Nocardia 107-332, a soil isolate, oxidizes short-chain alkyl-substituted cyclic hydrocarbons to cyclic acids while growing on n-alkanes. Cyclic acids are produced also from relatively long-chain alkyl-substituted cyclics such as n-nonylbenzene or n-dodecylbenzene which alone support growth in a mineral-salts medium. ?-Oxidation of the alkyl substituents is followed by ?-oxidation. It is of particular interest that cyclic acids such as cyclohexaneacetic and phenylacetic with C2 residual carboxylic acid substituents are resistant to further oxidation by the nocardia but cyclic acids with C1 or C3 substituents are readily oxidized and utilized for growth. The specificity of microbial oxidations is demonstrated by the conversion of p-isopropyltoluene (p-cymene) to p-isopropylbenzoic acid in n-alkane, growth-supported nocardia cultures. PMID:13720182

  15. Light hydrocarbon gas conversion using porphyrin catalysts

    SciTech Connect

    Showalter, M.C.; Shelnutt, J.A.

    1995-07-01

    The objective of this project is to develop novel catalysts for the direct conversion of natural gas to a liquid fuel. The current work investigates the use of biomimetic metalloporphyrins as catalysts for the partial oxidation of light alkanes to alcohols.

  16. Oxidative dehydrogenation of alkanes to unsaturated hydrocarbons

    DOEpatents

    Kung, Harold H. (Wilmette, IL); Chaar, Mohamed A. (Homs, SY)

    1988-01-01

    Oxidative dehydrogenation of alkanes to unsaturated hydrocarbons is carried out over metal vanadate catalysts under oxidizing conditions. The vanadate catalysts are represented by the formulas M.sub.3 (VO.sub.4).sub.2 and MV.sub.2 O.sub.6, M representing Mg, Zn, Ca, Pb, or Cd. The reaction is carried out in the presence of oxygen, but the formation of oxygenate by-products is suppressed.

  17. Oxidative dehydrogenation of alkanes to unsaturated hydrocarbons

    DOEpatents

    Kung, H.H.; Chaar, M.A.

    1988-10-11

    Oxidative dehydrogenation of alkanes to unsaturated hydrocarbons is carried out over metal vanadate catalysts under oxidizing conditions. The vanadate catalysts are represented by the formulas M[sub 3](VO[sub 4])[sub 2] and MV[sub 2]O[sub 6], M representing Mg, Zn, Ca, Pb, or Cd. The reaction is carried out in the presence of oxygen, but the formation of oxygenate by-products is suppressed.

  18. Electrophilic nitration of alkanes with nitronium hexafluorophosphate

    PubMed Central

    Olah, George A.; Ramaiah, Pichika; Prakash, G. K. Surya

    1997-01-01

    Nitration of alkanes such as methane, ethane, propane, n-butane, isobutane, neopentane, and cyclohexane was carried out with nitronium hexafluorophosphate in methylene chloride or nitroethane solution. Nitration of methane, albeit in poor yield, required protolytic activation of the nitronium ion. The results indicate direct electrophilic insertion of NO2+ into C 000000000000 000000000000 000000000000 000000000000 111111111111 000000000000 000000000000 000000000000 000000000000 H and CC ?-bonds. PMID:11038587

  19. Cytochrome P450 Alkane Hydroxylases of the CYP153 Family Are Common in Alkane-Degrading Eubacteria Lacking Integral Membrane Alkane Hydroxylases

    PubMed Central

    van Beilen, Jan B.; Funhoff, Enrico G.; van Loon, Alexander; Just, Andrea; Kaysser, Leo; Bouza, Manuel; Holtackers, Ren; Rthlisberger, Martina; Li, Zhi; Witholt, Bernard

    2006-01-01

    Several strains that grow on medium-chain-length alkanes and catalyze interesting hydroxylation and epoxidation reactions do not possess integral membrane nonheme iron alkane hydroxylases. Using PCR, we show that most of these strains possess enzymes related to CYP153A1 and CYP153A6, cytochrome P450 enzymes that were characterized as alkane hydroxylases. A vector for the polycistronic coexpression of individual CYP153 genes with a ferredoxin gene and a ferredoxin reductase gene was constructed. Seven of the 11 CYP153 genes tested allowed Pseudomonas putida GPo12 recombinants to grow well on alkanes, providing evidence that the newly cloned P450s are indeed alkane hydroxylases. PMID:16391025

  20. Alkene Protonation Enthalpy Determination from Fundamental Kinetic Modeling of Alkane Hydroconversion on Pt\\/H(US)Y-Zeolite

    Microsoft Academic Search

    J. W Thybaut; G. B Marin; G. V Baron; P. A Jacobs; J. A Martens

    2001-01-01

    Alkane, c.q., C5 to C12, hydrocracking was performed on Pt\\/HY-zeolite and on Pt\\/HUSY-zeolites with Si\\/Al ratio of 13 and 30 at temperatures of 506563 K, pressures of 0.451.5 MPa, and molar hydrogen to hydrocarbon ratio's in the 4.23250 range. The catalytic conversion was described with a fundamental molecular model, relying on experimentally determined physisorption equilibria and on a network of

  1. Cracking of naphtha range alkanes and naphthenes over zeolites

    Microsoft Academic Search

    Hayim Abrevaya

    2007-01-01

    Naphtha range alkanes and naphthenes can be activated over H-form of zeolites, which provide low temperature cracking pathways that are otherwise unavailable during conventional steam cracking. A range of zeolitic catalysts were tested for cracking naphtha. Due to their relatively larger kinetic diameter, isoalkanes and naphthenes exhibited lower reactivity than linear alkanes over 8-MR zeolites. 12-MR zeolites favored bimolecular hydride

  2. Energy conversion and storage program

    Microsoft Academic Search

    E. J. Cairns

    1992-01-01

    The Energy Conversion and Storage Program applies chemistry and materials science principles to solve problems in: (1) production of new synthetic fuels; (2) development of high-performance rechargeable batteries and fuel cells; (3) development of advanced thermochemical processes for energy conversion; (4) characterization of complex chemical processes; and (5) application of novel materials for energy conversion and transmission. Projects focus on

  3. Resonant diffusion of normal alkanes in zeolites: Effect of the zeolite structure and alkane molecule vibrations

    E-print Network

    Tsekov, R

    2015-01-01

    Diffusion of normal alkanes in one-dimensional zeolites is theoretically studied on the basis of the stochastic equation formalism. The calculated diffusion coefficient accounts for the vibrations of the diffusing molecule and zeolite framework, molecule-zeolite interaction, and specific structure of the zeolite. It is shown that when the interaction potential is predominantly determined by the zeolite pore structure, the diffusion coefficient varies periodically with the number of carbon atoms of the alkane molecule, a phenomenon called resonant diffusion. A criterion for observable resonance is obtained from the balance between the interaction potentials of the molecule due to the atomic and pore structures of the zeolite. It shows that the diffusion is not resonant in zeolites without pore structure, such as ZSM-12. Moreover, even in zeolites with developed pore structure no resonant dependence of the diffusion constant can be detected if the pore structure energy barriers are not at least three times high...

  4. Long-chain alkane production by the yeast Saccharomyces cerevisiae.

    PubMed

    Buijs, Nicolaas A; Zhou, Yongjin J; Siewers, Verena; Nielsen, Jens

    2015-06-01

    In the past decade industrial-scale production of renewable transportation biofuels has been developed as an alternative to fossil fuels, with ethanol as the most prominent biofuel and yeast as the production organism of choice. However, ethanol is a less efficient substitute fuel for heavy-duty and maritime transportation as well as aviation due to its low energy density. Therefore, new types of biofuels, such as alkanes, are being developed that can be used as drop-in fuels and can substitute gasoline, diesel, and kerosene. Here, we describe for the first time the heterologous biosynthesis of long-chain alkanes by the yeast Saccharomyces cerevisiae. We show that elimination of the hexadecenal dehydrogenase Hfd1 and expression of a redox system are essential for alkane biosynthesis in yeast. Deletion of HFD1 together with expression of an alkane biosynthesis pathway resulted in the production of the alkanes tridecane, pentadecane, and heptadecane. Our study provides a proof of principle for producing long-chain alkanes in the industrial workhorse S. cerevisiae, which was so far limited to bacteria. We anticipate that these findings will be a key factor for further yeast engineering to enable industrial production of alkane based drop-in biofuels, which can allow the biofuel industry to diversify beyond bioethanol. Biotechnol. Bioeng. 2015;112: 1275-1279. 2014 Wiley Periodicals, Inc. PMID:25545362

  5. Kinetic study of asphaltene dissolution in amphiphile/alkane solutions

    SciTech Connect

    Permsukarome, P. [Chulalongkorn Univ., Bangkok (Thailand). Petrochemical Coll.] [Chulalongkorn Univ., Bangkok (Thailand). Petrochemical Coll.; Chang, C.; Fogler, H.S. [Univ. of Michigan, Ann Arbor, MI (United States). Dept. of Chemical Engineering] [Univ. of Michigan, Ann Arbor, MI (United States). Dept. of Chemical Engineering

    1997-09-01

    The kinetics of dissolution of pentane-insoluble solid asphaltene precipitates by amphiphile/alkane solutions were investigated using a differential reactor flow system. Two amphiphiles, dodecylbenzenesulfonic acid and nonylphenol, and five alkane solvents, ranging from hexane to hexadecane, were used. Results showed that the rate of asphaltene dissolution in amphiphile/alkane fluids could be approximated with a first-order kinetics with respect to the undissolved asphaltene mass in solution. The specific dissolution rate constant, k, varied with the concentration of amphiphiles, the type of alkane solvents, the temperature, and the fluid flow rate. The rate of asphaltene dissolution displayed a Langmuir-Hinshelwood kinetics with respect to the concentration of amphiphiles. Increasing the temperature of amphiphile/alkane fluids also enhanced the rate of asphaltene dissolution. The apparent activation energy for asphaltene dissolution was approximated to be 4--7 kcal/mol. The rate of asphaltene dissolution was also greater in amphiphile solutions containing lighter alkanes, such as hexane, with lower viscosities. These trends suggest that both surface reaction and mass transfer processes are important to the rate of asphaltene dissolution in amphiphile/alkane fluids.

  6. Heterogeneity of alkane chain length in freshwater and marine cyanobacteria.

    PubMed

    Shakeel, Tabinda; Fatma, Zia; Fatma, Tasneem; Yazdani, Syed Shams

    2015-01-01

    The potential utilization of cyanobacteria for the biological production of alkanes represents an exceptional system for the next generation of biofuels. Here, we analyzed a diverse group of freshwater and marine cyanobacterial isolates from Indian culture collections for their ability to produce both alkanes and alkenes. Among the 50 cyanobacterial isolates screened, 32 isolates; 14 freshwater and 18 marine isolates; produced predominantly alkanes. The GC-MS/MS profiles revealed a higher percentage of pentadecane and heptadecane production for marine and freshwater strains, respectively. Oscillatoria species were found to be the highest producers of alkanes. Among the freshwater isolates, Oscillatoria CCC305 produced the maximum alkane level with 0.43??g/mg dry cell weight, while Oscillatoria formosa BDU30603 was the highest producer among the marine isolates with 0.13??g/mg dry cell weight. Culturing these strains under different media compositions showed that the alkane chain length was not influenced by the growth medium but was rather an inherent property of the strains. Analysis of the cellular fatty acid content indicated the presence of predominantly C16 chain length fatty acids in marine strains, while the proportion of C18 chain length fatty acids increased in the majority of freshwater strains. These results correlated with alkane chain length specificity of marine and freshwater isolates indicating that alkane chain lengths may be primarily determined by the fatty acid synthesis pathway. Moreover, the phylogenetic analysis showed clustering of pentadecane-producing marine strains that was distinct from heptadecane-producing freshwater strains strongly suggesting a close association between alkane chain length and the cyanobacteria habitat. PMID:25853127

  7. Alkane separation using nanoporous graphene membranes.

    PubMed

    Nieszporek, Krzysztof; Drach, Mateusz

    2015-01-14

    We studied the permeability of graphene sheets with designed nanopores using the classical molecular dynamics. To characterize the energy profile for transmission we calculated the potential of the mean force. A high selectivity for methane + butane mixture with the hydrogen-passivated pore diameter of 0.32 nm was found where the volume exclusion mechanism governs the separation process. In the case of a slightly larger pore diameter of 0.64 nm the same alkane mixture separates completely unexpectedly: a larger butane molecule permeates much faster than a small methane one. The blocking effect of the permeation path by a larger mixture component when it worked like a cork was also observed. This is a promising perspective for using graphene to design intelligent membranes which can maintain a constant composition of mixtures in the permeable area. PMID:25410377

  8. Involvement of an Alkane Hydroxylase System of Gordonia sp. Strain SoCg in Degradation of Solid n-Alkanes?

    PubMed Central

    Lo Piccolo, Luca; De Pasquale, Claudio; Fodale, Roberta; Puglia, Anna Maria; Quatrini, Paola

    2011-01-01

    Enzymes involved in oxidation of long-chain n-alkanes are still not well known, especially those in Gram-positive bacteria. This work describes the alkane degradation system of the n-alkane degrader actinobacterium Gordonia sp. strain SoCg, which is able to grow on n-alkanes from dodecane (C12) to hexatriacontane (C36) as the sole C source. SoCg harbors in its chromosome a single alk locus carrying six open reading frames (ORFs), which shows 78 to 79% identity with the alkane hydroxylase (AH)-encoding systems of other alkane-degrading actinobacteria. Quantitative reverse transcription-PCR showed that the genes encoding AlkB (alkane 1-monooxygenase), RubA3 (rubredoxin), RubA4 (rubredoxin), and RubB (rubredoxin reductase) were induced by both n-hexadecane and n-triacontane, which were chosen as representative long-chain liquid and solid n-alkane molecules, respectively. Biotransformation of n-hexadecane into the corresponding 1-hexadecanol was detected by solid-phase microextraction coupled with gas chromatography-mass spectrometry (SPME/GC-MS) analysis. The Gordonia SoCg alkB was heterologously expressed in Escherichia coli BL21 and in Streptomyces coelicolor M145, and both hosts acquired the ability to transform n-hexadecane into 1-hexadecanol, but the corresponding long-chain alcohol was never detected on n-triacontane. However, the recombinant S. coelicolor M145-AH, expressing the Gordonia alkB gene, was able to grow on n-triacontane as the sole C source. A SoCg alkB disruption mutant that is completely unable to grow on n-triacontane was obtained, demonstrating the role of an AlkB-type AH system in degradation of solid n-alkanes. PMID:21183636

  9. Basic Chemistry Review

    NSDL National Science Digital Library

    Thomas Meixner

    This assignment reviews basic of chemistry for students who should have had 2 introductory semesters of basic chemistry prior to enrolling in the Fundamental of Water Quality course for which the assignment is used. Assignment reviews basic equation balancing and questions about valence and concentration conversion that students will confront regularly in any geochemistry course.

  10. A Toolkit to Enable Hydrocarbon Conversion in Aqueous Environments

    PubMed Central

    Brinkman, Eva K.; Schipper, Kira; Bongaerts, Nadine; Voges, Mathias J.; Abate, Alessandro; Wahl, S. Aljoscha

    2012-01-01

    This work puts forward a toolkit that enables the conversion of alkanes by Escherichia coli and presents a proof of principle of its applicability. The toolkit consists of multiple standard interchangeable parts (BioBricks)9 addressing the conversion of alkanes, regulation of gene expression and survival in toxic hydrocarbon-rich environments. A three-step pathway for alkane degradation was implemented in E. coli to enable the conversion of medium- and long-chain alkanes to their respective alkanols, alkanals and ultimately alkanoic-acids. The latter were metabolized via the native ?-oxidation pathway. To facilitate the oxidation of medium-chain alkanes (C5-C13) and cycloalkanes (C5-C8), four genes (alkB2, rubA3, rubA4and rubB) of the alkane hydroxylase system from Gordonia sp. TF68,21 were transformed into E. coli. For the conversion of long-chain alkanes (C15-C36), theladA gene from Geobacillus thermodenitrificans was implemented. For the required further steps of the degradation process, ADH and ALDH (originating from G. thermodenitrificans) were introduced10,11. The activity was measured by resting cell assays. For each oxidative step, enzyme activity was observed. To optimize the process efficiency, the expression was only induced under low glucose conditions: a substrate-regulated promoter, pCaiF, was used. pCaiF is present in E. coli K12 and regulates the expression of the genes involved in the degradation of non-glucose carbon sources. The last part of the toolkit - targeting survival - was implemented using solvent tolerance genes, PhPFD? and ?, both from Pyrococcus horikoshii OT3. Organic solvents can induce cell stress and decreased survivability by negatively affecting protein folding. As chaperones, PhPFD? and ? improve the protein folding process e.g. under the presence of alkanes. The expression of these genes led to an improved hydrocarbon tolerance shown by an increased growth rate (up to 50%) in the presences of 10% n-hexane in the culture medium were observed. Summarizing, the results indicate that the toolkit enables E. coli to convert and tolerate hydrocarbons in aqueous environments. As such, it represents an initial step towards a sustainable solution for oil-remediation using a synthetic biology approach. PMID:23052445

  11. Bacterial metabolism of long-chain n -alkanes

    Microsoft Academic Search

    Alexander Wentzel; Trond E. Ellingsen; Hans-Kristian Kotlar; Sergey B. Zotchev; Mimmi Throne-Holst

    2007-01-01

    Degradation of alkanes is a widespread phenomenon in nature, and numerous microorganisms, both prokaryotic and eukaryotic,\\u000a capable of utilizing these substrates as a carbon and energy source have been isolated and characterized. In this review,\\u000a we summarize recent advances in the understanding of bacterial metabolism of long-chain n-alkanes. Bacterial strategies for accessing these highly hydrophobic substrates are presented, along with

  12. Hydrogen-hydrogen bonds in highly branched alkanes and in alkane complexes: A DFT, ab initio, QTAIM, and ELF study.

    PubMed

    Monteiro, Norberto K V; Firme, Caio L

    2014-03-01

    The hydrogen-hydrogen (H-H) bond or hydrogen-hydrogen bonding is formed by the interaction between a pair of identical or similar hydrogen atoms that are close to electrical neutrality and it yields a stabilizing contribution to the overall molecular energy. This work provides new, important information regarding hydrogen-hydrogen bonds. We report that stability of alkane complexes and boiling point of alkanes are directly related to H-H bond, which means that intermolecular interactions between alkane chains are directional H-H bond, not nondirectional induced dipole-induced dipole. Moreover, we show the existence of intramolecular H-H bonds in highly branched alkanes playing a secondary role in their increased stabilities in comparison with linear or less branched isomers. These results were accomplished by different approaches: density functional theory (DFT), ab initio, quantum theory of atoms in molecules (QTAIM), and electron localization function (ELF). PMID:24533436

  13. Chemistry 321 Organic Chemistry

    E-print Network

    Wagner, Diane

    Chemistry 321 Organic Chemistry Fall 2010 MWF 1:00-2:00 Reichardt Bldg 202 Instructor: Thomas Dept.) Office Hours: By appointment Required Materials: Organic Chemistry 7th Ed., J. McMurry, Brooks/Cole OWL card RF classroom clicker Recommended: Study Guide & Solutions Manual for Org Chemistry HGS

  14. CHEMISTRY 11500 General Chemistry

    E-print Network

    Jiang, Wen

    CHEMISTRY 11500 General Chemistry Spring 2014 Professor Dr. John J. Nash; BRWN 4103C; phone: 494.edu (Lab) Required Course Materials Chemistry: The Molecular Nature of Matter and Change, 6th Ed., by M. S. Silberberg, McGraw-Hill, 2012. Chemistry 11500 Laboratory Manual, 2013-2014, Hayden-McNeil Publishing, Inc

  15. Energy Conversion and Storage Program

    Microsoft Academic Search

    E. J. Cairns

    1993-01-01

    This report is the 1992 annual progress report for the Energy Conversion and Storage Program, a part of the Energy and Environment Division of the Lawrence Berkeley Laboratory. Work described falls into three broad areas: electrochemistry; chemical applications; and materials applications. The Energy Conversion and Storage Program applies principles of chemistry and materials science to solve problems in several areas:

  16. 40 CFR 721.10103 - Naphtha (Fischer-Tropsch), C4-11-alkane, branched and linear.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... false Naphtha (Fischer-Tropsch), C4-11-alkane, branched and linear. ...10103 Naphtha (Fischer-Tropsch), C4-11-alkane, branched and linear. ...identified as naphtha (fischer-tropsch), C4-11-alkane, branched and...

  17. 40 CFR 721.10103 - Naphtha (Fischer-Tropsch), C4-11-alkane, branched and linear.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... false Naphtha (Fischer-Tropsch), C4-11-alkane, branched and linear. ...10103 Naphtha (Fischer-Tropsch), C4-11-alkane, branched and linear. ...identified as naphtha (fischer-tropsch), C4-11-alkane, branched and...

  18. Variation in n-Alkane Distributions of Modern Plants: Questioning Applications of n-Alkanes in Chemotaxonomy and Paleoecology

    NASA Astrophysics Data System (ADS)

    Bush, R. T.; McInerney, F. A.

    2010-12-01

    Long chain n-alkanes (n-C21 to n-C37) are synthesized as part of the epicuticular leaf wax of terrestrial plants and are among the most recognizable and widely used plant biomarkers. n-Alkane distributions have been utilized in previous studies on modern plant chemotaxonomy, testing whether taxa can be identified based on characteristic n-alkane profiles. Dominant n-alkanes (e.g. n-C27 or n-C31) have also been ascribed to major plant groups (e.g. trees or grasses respectively) and have been used in paleoecology studies to reconstruct fluctuations in plant functional types. However, many of these studies have been based on relatively few modern plant data; with the wealth of modern n-alkane studies, a more comprehensive analysis of n-alkanes in modern plants is now possible and can inform the usefulness of n-alkane distributions as paleoecological indicators. The work presented here is a combination of measurements made using plant leaves collected from the Chicago Botanic Garden and a compilation of published literature data from six continents. We categorized plants by type: angiosperms, gymnosperms, woody plants, forbs, grasses, ferns and pteridophytes, and mosses. We then quantified n-alkane distribution parameters such as carbon preference index (CPI), average chain length (ACL), and dispersion (a measure of the spread of the profile over multiple chain lengths) and used these to compare plant groups. Among all plants, one of the emergent correlations is a decrease in dispersion with increasing CPI. Within and among plant groups, n-alkane distributions show a very large range of variation, and the results show little or no correspondence between broad plant groups and a single dominant n-alkane or a ratio of n-alkanes. These findings are true both when data from six continents are combined and when plants from a given region are compared (North America). We also compared the n-alkane distributions of woody angiosperms, woody gymnosperms, and grasses with one another in order to test whether n-C27 and n-C29 represent trees and shrubs while n-C31 represents grasses as previously proposed. The average group profiles are not distinguishable from one another due to their large standard deviations. Although n-C31 is the predominant chain length in many (but not all) grasses, other chain lengths such as n-C29 are also abundant. For grasses as a group one chain length does not dominate significantly over the other. In mosses, while the genus Sphagnum appears to be typified by n-C23 and n-C25 alkanes, the same cannot be said for other moss genera which were more dominated by n-C27 and n-C29. Differences in n-alkane distributions may relate more to environmental changes such as temperature and precipitation than to shifts in dominant plant types.

  19. Department of Chemistry & Biochemistry UCLA Chemistry, Biochemistry & Chemistry Material Science

    E-print Network

    Levine, Alex J.

    ..............................................................................................................................................................11 Physical Chemistry ConcentrationDepartment of Chemistry & Biochemistry UCLA Chemistry, Biochemistry & Chemistry Material Science ...........................................................................................................................................4 Chemistry & Biochemistry Undergraduate Office

  20. Enzymes involved in the anaerobic oxidation of n-alkanes: from methane to long-chain paraffins

    PubMed Central

    Callaghan, Amy V.

    2013-01-01

    Anaerobic microorganisms play key roles in the biogeochemical cycling of methane and non-methane alkanes. To date, there appear to be at least three proposed mechanisms of anaerobic methane oxidation (AOM). The first pathway is mediated by consortia of archaeal anaerobic methane oxidizers and sulfate-reducing bacteria (SRB) via reverse methanogenesis and is catalyzed by a homolog of methyl-coenzyme M reductase. The second pathway is also mediated by anaerobic methane oxidizers and SRB, wherein the archaeal members catalyze both methane oxidation and sulfate reduction and zero-valent sulfur is a key intermediate. The third AOM mechanism is a nitrite-dependent, intra-aerobic pathway described for the denitrifying bacterium, Candidatus Methylomirabilis oxyfera. It is hypothesized that AOM proceeds via reduction of nitrite to nitric oxide, followed by the conversion of two nitric oxide molecules to dinitrogen and molecular oxygen. The latter can be used to functionalize the methane via a particulate methane monooxygenase. With respect to non-methane alkanes, there also appear to be novel mechanisms of activation. The most well-described pathway is the addition of non-methane alkanes across the double bond of fumarate to form alkyl-substituted succinates via the putative glycyl radical enzyme, alkylsuccinate synthase (also known as methylalkylsuccinate synthase). Other proposed mechanisms include anaerobic hydroxylation via ethylbenzene dehydrogenase-like enzymes and an intra-aerobic denitrification pathway similar to that described for Methylomirabilis oxyfera. PMID:23717304

  1. Alkanes in shrimp from the Buccaneer Oil Field

    SciTech Connect

    Middleditch, B.S.; Basile, B.; Chang, E.S.

    1982-07-01

    A total of 36 samples of shrimp were examined from the region of the Buccaneer oil field, eighteen of which were representatives of the commercial species Penaeus aztecus and the rest were various other species: Penaeus duorarum (pink shrimp), Trachypenaeus duorarum (sugar shrimp), Squilla empusa (mantis shrimp), and Sicyonia dorsalis (chevron shrimp). The alkanes and deuteriated alkanes were completely separated by GC, so a mass spectrometer was not required for their detection and quantitation. To confirm the identities of individual compounds, however, some samples were examined by combined gas chromatography-mass spectrometry. Results show that only thirteen of the forty shrimp collected from the region of the Buccaneer oil field contained petroleum alkanes, and the majority of these were obtained from trawls immediately adjacent to the production platforms. It appears that shrimp caught in the region of the Buccaneer oil field are not appreciably tainted with hydrocarbons discharged from the production platforms. (JMT)

  2. Surface crystallization in normal-alkanes and alcohols

    SciTech Connect

    Deutsch, M. [Bar Ilan Univ., Ramat-Gan (Israel). Physics Dept.; Ocko, B.M. [Brookhaven National Lab., Upton, NY (United States). Physics Dept.; Wu, X.Z. [Northern Illinois Univ., DeKalb, IL (United States). Physics Dept.]|[Exxon Research and Engineering Co., Annandale, NJ (United States). Corporate Research Science Lab.; Sirota, E.B.; Sinha, S.K. [Exxon Research and Engineering Co., Annandale, NJ (United States). Corporate Research Science Lab.

    1995-06-01

    A new, rare surface freezing, phenomenon is observed in molten normal-alkanes and their derivatives (alcohols, thiols, etc.). X-ray and surface tension measurements show the formation of a crystalline monolayer on the surface of the liquid alkane at temperatures up to 3 C above the bulk solidification temperature, T{sub f}. For alcohols, a single bilayer is formed. In both cases, the molecules in the layer are hexagonally packed and oriented normal to the surface for short chain lengths, and tilted for long ones. In both cases the single layer persists down to T{sub f}. In terms of wetting theory, this constitutes a very limited partial wetting of the liquid surface by the crystalline layer. The new surface phase is obtained only for chain lengths 14 < n {le} 50 in alkanes, and 16 < n < 30 in alcohols. The measurements are satisfactorily accounted for within a simple theory based on surface energy considerations.

  3. Regioselective alkane hydroxylation with a mutant AlkB enzyme

    DOEpatents

    Koch, Daniel J.; Arnold, Frances H.

    2012-11-13

    AlkB from Pseudomonas putida was engineered using in-vivo directed evolution to hydroxylate small chain alkanes. Mutant AlkB-BMO1 hydroxylates propane and butane at the terminal carbon at a rate greater than the wild-type to form 1-propanol and 1-butanol, respectively. Mutant AlkB-BMO2 similarly hydroxylates propane and butane at the terminal carbon at a rate greater than the wild-type to form 1-propanol and 1-butanol, respectively. These biocatalysts are highly active for small chain alkane substrates and their regioselectivity is retained in whole-cell biotransformations.

  4. Leaf-wax n-alkanes record the plantwater environment at leaf ush

    E-print Network

    Tipple, Brett

    Leaf-wax n-alkanes record the plantwater environment at leaf ush Brett J. Tipple1 , Melissa A, UT, and approved December 26, 2012 (received for review August 13, 2012) Leaf-wax n-alkanes 2 H/1 H the 2 H values of leaf-wax n-alkanes and of stem, leaf, stream, and atmospheric waters throughout

  5. Isolating the non-polar contributions to the intermolecular potential for water-alkane interactions.

    PubMed

    Ballal, Deepti; Venkataraman, Pradeep; Fouad, Wael A; Cox, Kenneth R; Chapman, Walter G

    2014-08-14

    Intermolecular potential models for water and alkanes describe pure component properties fairly well, but fail to reproduce properties of water-alkane mixtures. Understanding interactions between water and non-polar molecules like alkanes is important not only for the hydrocarbon industry but has implications to biological processes as well. Although non-polar solutes in water have been widely studied, much less work has focused on water in non-polar solvents. In this study we calculate the solubility of water in different alkanes (methane to dodecane) at ambient conditions where the water content in alkanes is very low so that the non-polar water-alkane interactions determine solubility. Only the alkane-rich phase is simulated since the fugacity of water in the water rich phase is calculated from an accurate equation of state. Using the SPC/E model for water and TraPPE model for alkanes along with Lorentz-Berthelot mixing rules for the cross parameters produces a water solubility that is an order of magnitude lower than the experimental value. It is found that an effective water Lennard-Jones energy ?(W)/k = 220?K is required to match the experimental water solubility in TraPPE alkanes. This number is much higher than used in most simulation water models (SPC/E-?(W)/k = 78.2?K). It is surprising that the interaction energy obtained here is also higher than the water-alkane interaction energy predicted by studies on solubility of alkanes in water. The reason for this high water-alkane interaction energy is not completely understood. Some factors that might contribute to the large interaction energy, such as polarizability of alkanes, octupole moment of methane, and clustering of water at low concentrations in alkanes, are examined. It is found that, though important, these factors do not completely explain the anomalously strong attraction between alkanes and water observed experimentally. PMID:25134597

  6. Dynamic Properties of Linear and Cyclic Alkane Melts

    NASA Astrophysics Data System (ADS)

    Ozisik, Rahmi; Mattice, Wayne L.; von Meerwall, Ernst D.

    2000-03-01

    The diffusion coefficients, D, of linear and cyclic alkanes in the melt were calculated by a Monte Carlo simulation on the second nearest neighbor diamond (2nnd) lattice. The results of the 2nnd simulations were compared to pulsed-gradient spin-echo nuclear magnetic resonance (PGSE NMR) experiments for the linear alkanes. The 2nnd lattice simulations were able to represent the bulk dynamic properties of linear alkane chains. D was influenced by two kinds of factors: local and global. Local factors are those that change the interactions of the individual beads, such as the occupancy of the neighboring shells, and global factors are those that change the interactions of the chains, such as the density and entanglement effects. In this study, the D of the cyclic chains was found to be lower than that of the linear chains at the same molecular weight below M_e. This crossover is attributed to the interplay between the local factors, which dominate the dynamics of the cyclic chains below M_e, and the entanglement effects above M_e. The cyclic alkane chain is smaller than a linear chain at all times. Below M_e, the high local density slows down the dynamics of the cyclic chains compared to the linear chains, and above M_e, the cyclic chains have higher D, because they are not affected by the entanglement effects observed by the linear chains.

  7. Diverse alkane hydroxylase genes in microorganisms and environments

    PubMed Central

    Nie, Yong; Chi, Chang-Qiao; Fang, Hui; Liang, Jie-Liang; Lu, She-Lian; Lai, Guo-Li; Tang, Yue-Qin; Wu, Xiao-Lei

    2014-01-01

    AlkB and CYP153 are important alkane hydroxylases responsible for aerobic alkane degradation in bioremediation of oil-polluted environments and microbial enhanced oil recovery. Since their distribution in nature is not clear, we made the investigation among thus-far sequenced 3,979 microbial genomes and 137 metagenomes from terrestrial, freshwater, and marine environments. Hundreds of diverse alkB and CYP153 genes including many novel ones were found in bacterial genomes, whereas none were found in archaeal genomes. Moreover, these genes were detected with different distributional patterns in the terrestrial, freshwater, and marine metagenomes. Hints for horizontal gene transfer, gene duplication, and gene fusion were found, which together are likely responsible for diversifying the alkB and CYP153 genes adapt to the ubiquitous distribution of different alkanes in nature. In addition, different distributions of these genes between bacterial genomes and metagenomes suggested the potentially important roles of unknown or less common alkane degraders in nature. PMID:24829093

  8. N-Alkane uptake and utilisation by Streptomyces strains.

    PubMed

    Barabs, G; Vargha, G; Szab, I M; Penyige, A; Damjanovich, S; Szllsi, J; Matk, J; Hirano, T; Mtyus, A; Szab, I

    2001-09-01

    Streptomyces strains isolated from the Kuwait Burgan oil field were defined as S. griseoflavus, S. parvus, and S. plicatus utilised n-hexadecane, n-octadecane (purified fractions of mineral oil), kerosene, and crude oil as sole carbon and energy sources. The strains were incubated with n-alkanes and increase of the fatty acid content with chain length equivalent to the employed n-alkanes was observed. Signal transducing GTP-binding proteins (GBPs) play an important role in n-alkane uptake in streptomycetes. Specific activators of GBPs increased the uptake of hydrocarbons. Using the hydrophobic fluorescent dye diphenylhexatrien (DPH) as a probe, it was found that the microviscosity of the hydrophobic inner region of the cellular membrane is significantly lower in hydrocarbon utilisers than in non-utilisers. This difference probably reflects differences in the fatty acid composition of the strains. When cultures were grown in n-alkane containing media, electron microscopy revealed that the hydrocarbon utilisers showed less-electron dense areas as inclusions in the cytoplasm. Soil samples inoculated with Streptomyces strains eliminated hydrocarbons much faster than those not containing these strains, serving as control. When inorganic medium was supplied with n-hexadecane-1-14C as sole carbon and energy source, radioactive CO2 was detected. Since streptomycetes have not been used until now for oil elimination, though they are known as abundant soil bacteria tolerating extreme conditions, their possible use for bioremediation of hydrocarbon contaminated soils is discussed. PMID:11816969

  9. Cyano- and polycyanometallo-porphyrins as catalysts for alkane oxidation

    DOEpatents

    Ellis, P.E. Jr.; Lyons, J.E.

    1995-01-17

    New compositions of matter comprising cyano-substituted metal complexes of porphyrins are catalysts for the oxidation of alkanes. The metal is iron, chromium, manganese, ruthenium, copper or cobalt. The porphyrin ring has cyano groups attached thereto in meso and/or [beta]-pyrrolic positions.

  10. Cyano- and polycyanometallo-porphyrins as catalysts for alkane oxidation

    DOEpatents

    Ellis, P.E. Jr.; Lyons, J.E.

    1993-05-18

    New compositions of matter comprising cyano-substituted metal complexes of porphyrins are catalysts for the oxidation of alkanes. The metal is iron, chromium, manganese, ruthenium, copper or cobalt. The porphyrin ring has cyano groups attached thereto in meso- and/or [beta]-pyrrolic positions.

  11. Functional Analysis of Alkane Hydroxylases from Gram-Negative and Gram-Positive Bacteria

    PubMed Central

    Smits, Theo H. M.; Balada, Stefanie B.; Witholt, Bernard; van Beilen, Jan B.

    2002-01-01

    We have cloned homologs of the Pseudomonas putida GPo1 alkane hydroxylase from Pseudomonas aeruginosa PAO1, Pseudomonas fluorescens CHA0, Alcanivorax borkumensis AP1, Mycobacterium tuberculosis H37Rv, and Prauserella rugosa NRRL B-2295. Sequence comparisons show that the level of protein sequence identity between the homologs is as low as 35%, and that the Pseudomonas alkane hydroxylases are as distantly related to each other as to the remaining alkane hydroxylases. Based on the observation that rubredoxin, an electron transfer component of the GPo1 alkane hydroxylase system, can be replaced by rubredoxins from other alkane hydroxylase systems, we have developed three recombinant host strains for the functional analysis of the novel alkane hydroxylase genes. Two hosts, Escherichia coli GEc137 and P. putida GPo12, were equipped with pGEc47?B, which encodes all proteins necessary for growth on medium-chain-length alkanes (C6 to C12), except a functional alkane hydroxylase. The third host was an alkB knockout derivative of P. fluorescens CHA0, which is no longer able to grow on C12 to C16 alkanes. All alkane hydroxylase homologs, except the Acinetobacter sp. ADP1 AlkM, allowed at least one of the three hosts to grow on n-alkanes. PMID:11872725

  12. Genetically assembled fluorescent biosensor for in situ detection of bio-synthesized alkanes.

    PubMed

    Wu, Wei; Zhang, Lei; Yao, Lun; Tan, Xiaoming; Liu, Xufeng; Lu, Xuefeng

    2015-01-01

    Construction of highly efficient microbial cell factories producing drop-in biofuel alkanes is severely limited due to the lack of a fast detection method against alkanes. Here we first developed a sensitive fluorescent biosensor for rapid and in situ monitoring of intracellular alkane synthesis. Using GFP as reporter, the biosensor could actively respond to the intracellular alkane products, especially for the mid- and long-chain alkanes synthesized in the recombinant Escherichia coli and give a concentration-dependent fluorescence response. Our results also suggested the feasibility of developing high-throughput strategies basing on the alkane biosensor device in E. coli, and thus will greatly facilitate the application of directed evolution strategies to further improve the alkane-producing microbial cell factories. PMID:26039923

  13. Hydrogen isotope composition of leaf wax n-alkanes in glaucous and non-glaucous varieties of wheat (Triticum spp.)

    NASA Astrophysics Data System (ADS)

    Pedentchouk, Nikolai; Eley, Yvette; Frizell-Armitage, Amelia; Uauy, Cristobal

    2015-04-01

    The use of the 2H/1H composition of terrestrial plants in climate and ecology studies depends on fundamental understanding of the processes within the plant that control fractionation of these two isotopes. Little is currently known about the extent of 2H/1H fractionation at different steps of biosynthesis, after the initial H uptake following leaf water photolysis. Knowing this effect is particularly important when seeking to interpret the 2H/1H composition of leaf wax biomarkers from plants that differ in the amount and type of individual compound classes in their leaf waxes. The purpose of this study was to investigate the link between the quantity and distribution of n-alkyl lipids in leaf waxes and their isotopic composition. We used a genetic approach to suppress glaucousness in 2 varieties of wheat (Alchemy and Malacca), which resulted in glaucous and non-glaucous phenotypes of both varieties. Both phenotypes were then grown outdoors under identical environmental conditions in central Norfolk, UK. At the end of the growing season, the plants were sampled for soil water, leaf water, and leaf wax isotopic measurements. Comparison of the leaf wax composition of the non-glaucous and glaucous phenotypes revealed that the non-glaucous varieties were characterised by the absence of diketones and a greater concentration of n-alkanes and primary alcohols.. Our results showed very small differences between glaucous and non-glaucous varieties with regard to soil (mean values, <2 per mil) and leaf (<1 per mil) water 2H/1H. Conversely, there was 15-20 and 10-15 per mil 2H-depletion in the C29 and C31 n-alkanes, respectively, from the non-glaucous phenotype. This 2H-depletion in the non-glaucous phenotype demonstrated that the suppression of diketone production and the increase in n-alkane and primary alcohol concentrations are linked with a shift in the 2H/1H composition of n-alkanes. The initial results of this work suggest that plants using the same environmental water, subjected to the same effects of evapotranspiration, but which differ in the amount and composition of leaf wax compounds, can exhibit large variation in their n-alkane 2H/1H. Our current work on determining the 2H/1H composition of other n-alkyl lipids from these plants will provide further details regarding the role of biosynthesis in controlling 2H/1H fractionation within leaf waxes.

  14. Tropospheric Chemistry

    NASA Technical Reports Server (NTRS)

    Mohnen, V.

    1984-01-01

    The fundamental processes that control the chemical composition and cycles of the global troposphere and how these processes and properties affect the physical behavior of the atmosphere are examined. The long-term information needs for tropospheric chemistry are: to be able to predict tropospheric responses to perturbations, both natural and anthropogenic, of these cycles, and to provide the information required for the maintenance and effective future management of the atmospheric component of our global life support system. The processes controlling global tropospheric biogeochemical cycles include: the input of trace species into the troposphere, their long-range transport and distribution as affected by the mean wind and vertical venting, their chemical transformations, including gas to particle conversion, leading to the appearance of aerosols or aqueous phase reactions inside cloud droplets, and their removal from the troposphere via wet (precipitation) and dry deposition.

  15. Chemistry 417 PHYSICAL CHEMISTRY LABORATORY

    E-print Network

    Richmond, Geraldine L.

    Chemistry 417 PHYSICAL CHEMISTRY LABORATORY Fall, 2008 Lecture: 13:00 Tuesday and Thursday 331 Senning tba 174 Klamath Required Texts: Chemistry 417: Physical Chemistry Laboratory - University.b.: This text is also used in Chemistry 429 Applied Mathematics for Physical Chemistry by James R. Barrante

  16. Nitrogen Oxide Atom-Transfer Redox Chemistry; Mechanism of NO(g) to Nitrite Conversion Utilizing ?-oxo Heme-Fe(III)-O-Cu(II)(L) Constructs.

    PubMed

    Hematian, Shabnam; Kenkel, Isabell; Shubina, Tatyana E; Drr, Maximilian; Liu, Jeffrey J; Siegler, Maxime A; Ivanovic-Burmazovic, Ivana; Karlin, Kenneth D

    2015-05-27

    While nitric oxide (NO, nitrogen monoxide) is a critically important signaling agent, its cellular concentrations must be tightly controlled, generally through its oxidative conversion to nitrite (NO2(-)) where it is held in reserve to be reconverted as needed. In part, this reaction is mediated by the binuclear heme a3/CuB active site of cytochrome c oxidase. In this report, the oxidation of NO(g) to nitrite is shown to occur efficiently in new synthetic ?-oxo heme-Fe(III)-O-Cu(II)(L) constructs (L being a tridentate or tetradentate pyridyl/alkylamino ligand), and spectroscopic and kinetic investigations provide detailed mechanistic insights. Two new X-ray structures of ?-oxo complexes have been determined and compared to literature analogs. All ?-oxo complexes react with 2 mol equiv NO(g) to give 1:1 mixtures of discrete [(L)Cu(II)(NO2(-))](+) plus ferrous heme-nitrosyl compounds; when the first NO(g) equiv reduces the heme center and itself is oxidized to nitrite, the second equiv of NO(g) traps the ferrous heme thus formed. For one ?-oxo heme-Fe(III)-O-Cu(II)(L) compound, the reaction with NO(g) reveals an intermediate species ("intermediate"), formally a bis-NO adduct, [(NO)(porphyrinate)Fe(II)-(NO2(-))-Cu(II)(L)](+) (?max = 433 nm), confirmed by cryo-spray ionization mass spectrometry and EPR spectroscopy, along with the observation that cooling a 1:1 mixture of [(L)Cu(II)(NO2(-))](+) and heme-Fe(II)(NO) to -125 C leads to association and generation of the key 433 nm UV-vis feature. Kinetic-thermodynamic parameters obtained from low-temperature stopped-flow measurements are in excellent agreement with DFT calculations carried out which describe the sequential addition of NO(g) to the ?-oxo complex. PMID:25974136

  17. Site isolation in vanadium phosphorus oxide alkane oxidation

    SciTech Connect

    Thompson, M R [Pacific Northwest Lab., Richland, WA (USA); Ebner, J R [Monsanto Co., St. Louis, MO (USA)

    1991-06-01

    Single crystal X-ray diffraction studies of vanadyl pyrophosphate indicate that at least two polytypical structures exists for this active and selective alkane oxidation catalyst. The crystal structures of these materials differ with respect to the symmetry and direction of columns of vanadyl groups within the unit cell. Single crystals of vanadyl pyrophosphate have been generated at extreme temperatures not often experienced by microcrystalline catalysts. The crystallography of the system suggests that other crystalline modifications or disordered phases might also exist. Zeroth-order models of crystal surface termination of vanadyl pyrophosphate have been constructed which conceptually illustrate the ability of vanadyl pyrophosphate to accommodate varying amounts of surface phosphorus parallel to (1,0,0), (0,1,0) and (0,2,4). Pyrophosphate termination of surfaces parallel to (1,0,0) likely results in the isolation of clusters of reactive centers and limits overoxidation of the alkane substrate. 23 refs., 6 figs.

  18. Evaporation rates of alkanes and alkanols from acoustically levitated drops

    Microsoft Academic Search

    Rudolf Tuckermann; Sigurd Bauerecker; Bernd Neidhart

    2002-01-01

    Evaporation constants of acoustically levitated drops from the homologue series of n-alkanes and 1-alkanols in ambient air have been evaluated by size and temperature measurements. The size of the pure liquid drops, within a diameter range of 0.1 to 2.5 mm, was monitored using a CCD camera, while temperature measurements were carried out by IR thermography. During drop evaporation, water

  19. Alkane Biosynthesis Genes in Cyanobacteria and Their Transcriptional Organization

    PubMed Central

    Klhn, Stephan; Baumgartner, Desire; Pfreundt, Ulrike; Voigt, Karsten; Schn, Verena; Steglich, Claudia; Hess, Wolfgang R.

    2014-01-01

    In cyanobacteria, alkanes are synthesized from a fatty acyl-ACP by two enzymes, acylacyl carrier protein reductase and aldehyde deformylating oxygenase. Despite the great interest in the exploitation for biofuel production, nothing is known about the transcriptional organization of their genes or the physiological function of alkane synthesis. The comparison of 115 microarray datasets indicates the relatively constitutive expression of aar and ado genes. The analysis of 181 available genomes showed that in 90% of the genomes both genes are present, likely indicating their physiological relevance. In 61% of them they cluster together with genes encoding acetyl-CoA carboxyl transferase and a short-chain dehydrogenase, strengthening the link to fatty acid metabolism and in 76% of the genomes they are located in tandem, suggesting constraints on the gene arrangement. However, contrary to the expectations for an operon, we found in Synechocystis sp. PCC 6803 specific promoters for the two genes, sll0208 (ado) and sll0209 (aar), which give rise to monocistronic transcripts. Moreover, the upstream located ado gene is driven by a proximal as well as a second, distal, promoter, from which a third transcript, the ~160?nt sRNA SyR9 is transcribed. Thus, the transcriptional organization of the alkane biosynthesis genes in Synechocystis sp. PCC 6803 is of substantial complexity. We verified all three promoters to function independently from each other and show a similar promoter arrangement also in the more distant Nodularia spumigena, Trichodesmium erythraeum, Anabaena sp. PCC 7120, Prochlorococcus MIT9313, and MED4. The presence of separate regulatory elements and the dominance of monocistronic mRNAs suggest the possible autonomous regulation of ado and aar. The complex transcriptional organization of the alkane synthesis gene cluster has possible metabolic implications and should be considered when manipulating the expression of these genes in cyanobacteria. PMID:25022427

  20. Dielectric constant of liquid alkanes and hydrocarbon mixtures

    NASA Technical Reports Server (NTRS)

    Sen, A. D.; Anicich, V. G.; Arakelian, T.

    1992-01-01

    The complex dielectric constants of n-alkanes with two to seven carbon atoms have been measured. The measurements were conducted using a slotted-line technique at 1.2 GHz and at atmospheric pressure. The temperature was varied from the melting point to the boiling point of the respective alkanes. The real part of the dielectric constant was found to decrease with increasing temperature and correlate with the change in the molar volume. An upper limit to all the loss tangents was established at 0.001. The complex dielectric constants of a few mixtures of liquid alkanes were also measured at room temperature. For a pentane-octane mixture the real part of the dielectric constant could be explained by the Clausius-Mosotti theory. For the mixtures of n-hexane-ethylacetate and n-hexane-acetone the real part of the dielectric constants could be explained by the Onsager theory extended to mixtures. The dielectric constant of the n-hexane-acetone mixture displayed deviations from the Onsager theory at the highest fractions of acetone. The dipole moments of ethylacetate and acetone were determined for dilute mixtures using the Onsager theory and were found to be in agreement with their accepted gas-phase values. The loss tangents of the mixtures exhibited a linear relationship with the volume fraction for low concentrations of the polar liquids.

  1. Recommended Liquid-Liquid Equilibrium Data. Part 1. Binary Alkane-Water Systems

    NASA Astrophysics Data System (ADS)

    Ma̧czy?ski, Andrzej; Wi?niewska-Goc?owska, Barbara; Gral, Marian

    2004-06-01

    The recommended liquid-liquid equilibrium (LLE) data for 32 binary n-alkane, isoalkane, and cycloalkane-water systems have been obtained after critical evaluation of all data (345 data sets) reported in the open literature up to the end of 2002. The evaluation of the alkane solubility data was based on a generalized equation, which allows prediction of the alkane solubility as a function of temperature. Using the predicted alkane solubilities the concentration of water in the alkane rich phase was calculated. The LLE calculations were performed with the equation of state appended with a chemical term (EoSC) proposed by Gral. The experimental solubilities of water in various alkanes were compared to each other and to the calculated values. The recommended data are presented in the form of individual pages containing tables, all the references, and optionally figures.

  2. Activation of C 2C 4 alkanes over acid and bifunctional zeolite catalysts

    Microsoft Academic Search

    G. Caeiro; R. H. Carvalho; X. Wang; M. A. N. D. A. Lemos; F. Lemos; M. Guisnet; F. Rama Ribeiro

    2006-01-01

    This review paper presents the significant advances which were made in the last decade in the understanding of the transformation over acid and bifunctional zeolite catalysts of the cheap and readily available C2C4 alkanes into more valuable products: mechanism of activation, reaction scheme, nature of the active sites. Both the transformations of pure alkanes: n-butane isomerization, C2C4 alkane aromatization and

  3. Photochemical dimerization and functionalization of alkanes, ethers, primary alcohols and silanes

    DOEpatents

    Crabtree, R.H.; Brown, S.H.

    1988-02-16

    The space-time yield and/or the selectivity of the photochemical dimerization of alkanes, ethers, primary alcohols and tertiary silanes with Hg and U.V. light is enhanced by refluxing the substrate in the irradiated reaction zone at a temperature at which the dimer product condenses and remains condensed promptly upon its formation. Cross-dimerization of the alkanes, ethers and silanes with primary alcohols is disclosed, as is the functionalization to aldehydes of the alkanes with carbon monoxide.

  4. Revised Charge Equilibration Parameters for More Accurate Hydration Free Energies of Alkanes

    PubMed Central

    Davis, Joseph E.; Patel, Sandeep

    2009-01-01

    We present a refined alkane charge equilibration (CHEQ) force field, improving our previously reported CHEQ alkane force field[1] to better reproduce experimental hydration free energies. Experimental hydration free energies of ethane, propane, butane, pentane, hexane, and heptane are reproduced to within 3.6% on average. We demonstrate that explicit polarization results in a shift in molecular dipole moment for water molecules associated with the alkane molecule. We also show that our new parameters do not have a significant effect on the alkane-water interactions as measured by the radial distribution function (RDF). PMID:20161648

  5. Brookhaven National Laboratory: Chemistry Department

    NSDL National Science Digital Library

    At this website, the Brookhaven National Laboratory presents its chemistry research dealing primarily with imaging and neuroscience, charge transfer for energy conversion, chemistry with ionizing radiation, catalysis and surface science, nanoscience, combustion, and nuclear chemistry. Within each category, users can find instructive text and supportive images about the specific projects and the leading researchers. Visitors can learn about the Beamline U7A at the National Synchrotron Light Source, the Laser-Electron Accelerator Facility (LEAF), the Positron Emission Tomography (PET) Facility, and other exceptional research facilities. The website features histories of the chemistry department and of the Brookhaven National Laboratory.

  6. Chemistry 675 Advanced Organic Chemistry

    E-print Network

    Doyle, Robert

    Fall 2014 Chemistry 675 Advanced Organic Chemistry MWF 10:35-11:30 AM 200 LSB Professor John D Description: CHE675 is a graduate-level organic chemistry course focused on physical organic chemistry, which in my office (CST 4-006) or my mailbox in the chemistry office (CST 1-014). Late problem sets will have

  7. Optimization of H3O+/O2+ Dual-mode Ionization in PTR-MS for Simultaneous Detection of Alkanes, Olefins and Aromatic Compounds

    NASA Astrophysics Data System (ADS)

    Amador-Muoz, O.; Misztal, P. K.; Weber, R.; Drozd, G.; Worton, D. R.; Goldstein, A. H.

    2014-12-01

    Measurements of VOC composition from fossil fuels are analytically challenging because of the complex mixture of hydrocarbons (saturated, unsaturated, aromatics, etc). Speciated chemical measurements typically rely on relatively slow GC separation. Proton transfer reaction mass spectrometry (PTR-MS) is advantageous due to its fast response and high sensitivity. The most common ionization mechanism applied to VOC detection by PTR-MS is proton transfer from hydronium ion (H3O+). However, alkanes cannot be detected using H3O+ ionization chemistry because their proton affinities are too low. Ionization of alkanes is possible via electron transfer and/or hydride abstraction using O2+ or NO+. We used PTR-MS to analyze aromatic, alkene and alkane (linear, branched and cyclic) compounds simultaneously not by switching the ionization agents, but by adjusting the drift tube voltage and optimizing the ratio of H3O+/O2+ produced in the instrument's ion source. The highest detection sensitivity for aromatic and alkene compounds was produced by proton transfer from H3O+, while hydride abstraction by O2+ allowed detection of alkanes. For alkanes, sensitivities ranged from 1.10.01 cps/ppbv for n-decane to 74.70.25 cps/ppbv for decalin. Sensitivities in O2+ mode were from 6 (Adamantane) to 146 (4-Methyl nonane) times higher than those obtained in H3O+ mode under the same ion source and drift tube voltage conditions. Sensitivities for butyl benzene and 1-decene were 1570.57 and 66.80.21 cps/ppbv, respectively. Sensitivity differences among C10 hydrocarbons are related to their structure, which affects their ionization energies (IE) and hence ease of hydride abstraction. Sensitivities at the parent ion mass were inversely correlated with IE (142 cps/ppbv/eV). This suggests higher electronic stability for cyclic non substituted compounds, followed by cyclic substituted, branch linear and linear C10 hydrocarbons. Although selectivity is a known shortcoming of quadrupole-based PTR-MS, we demonstrated that, when optimized, it can be a useful tool to study alkanes, olefins, and aromatics simultaneously in high concentration plumes or in a laboratory. AMO acknowledges financial support of UCMEXUS-CONACyT Program for the Postdoctoral Fellowship

  8. Two Novel Alkane Hydroxylase-Rubredoxin Fusion Genes Isolated from a Dietzia Bacterium and the Functions of Fused Rubredoxin Domains in Long-Chain n-Alkane Degradation?

    PubMed Central

    Nie, Yong; Liang, Jieliang; Fang, Hui; Tang, Yue-Qin; Wu, Xiao-Lei

    2011-01-01

    Two alkane hydroxylase-rubredoxin fusion gene homologs (alkW1 and alkW2) were cloned from a Dietzia strain, designated DQ12-45-1b, which can grow on crude oil and n-alkanes ranging in length from 6 to 40 carbon atoms as sole carbon sources. Both AlkW1 and AlkW2 have an integral-membrane alkane monooxygenase (AlkB) conserved domain and a rubredoxin (Rd) conserved domain which are fused together. Phylogenetic analysis showed that these two AlkB-fused Rd domains formed a novel third cluster with all the Rds from the alkane hydroxylase-rubredoxin fusion gene clusters in Gram-positive bacteria and that this third cluster was distant from the known AlkG1- and AlkG2-type Rds. Expression of the alkW1 gene in DQ12-45-1b was induced when cells were grown on C8 to C32 n-alkanes as sole carbon sources, but expression of the alkW2 gene was not detected. Functional heterologous expression in an alkB deletion mutant of Pseudomonas fluorescens KOB2?1 suggested the alkW1 could restore the growth of KOB2?1 on C14 and C16 n-alkanes and induce faster growth on C18 to C32 n-alkanes than alkW1?Rd, the Rd domain deletion mutant gene of alkW1, which also caused faster growth than KOB2?1 itself. In addition, the artificial fusion of AlkB from the Gram-negative P. fluorescens CHA0 and the Rds from both Gram-negative P. fluorescens CHA0 and Gram-positive Dietzia sp. DQ12-45-1b significantly increased the degradation of C32 alkane compared to that seen with AlkB itself. In conclusion, the alkW1 gene cloned from Dietzia species encoded an alkane hydroxylase which increased growth on and degradation of n-alkanes up to C32 in length, with its fused rubredoxin domain being necessary to maintain the functions. In addition, the fusion of alkane hydroxylase and rubredoxin genes from both Gram-positive and -negative bacteria can increase the degradation of long-chain n-alkanes (such as C32) in the Gram-negative bacterium. PMID:21873474

  9. Contentious Conversations

    ERIC Educational Resources Information Center

    Zuidema, Leah A.

    2011-01-01

    The idea of joining a conversation through reading and writing is not new; in his 1941 book "The Philosophy of Literary Form: Studies in Symbolic Action," Kenneth Burke suggests that the acts of reading and writing are like entering a parlor where others are already conversing. The author explores the place of professional debate within NCTE and

  10. Transporter engineering for improved tolerance against alkane biofuels in Saccharomyces cerevisiae

    PubMed Central

    2013-01-01

    Background Hydrocarbon alkanes, components of major fossil fuels, are considered as next-generation biofuels because their biological production has recently been shown to be possible. However, high-yield alkane production requires robust host cells that are tolerant against alkanes, which exhibit cytotoxicity. In this study, we aimed to improve alkane tolerance in Saccharomyces cerevisiae, a key industrial microbial host, by harnessing heterologous transporters that potentially pump out alkanes. Results To this end, we attempted to exploit ABC transporters in Yarrowia lipolytica based on the observation that it utilizes alkanes as a carbon source. We confirmed the increased transcription of ABC2 and ABC3 transporters upon exposure to a range of alkanes in Y. lipolytica. We then showed that the heterologous expression of ABC2 and ABC3 transporters significantly increased tolerance against decane and undecane in S. cerevisiae through maintaining lower intracellular alkane level. In particular, ABC2 transporter increased the tolerance limit of S. cerevisiae about 80-fold against decane. Furthermore, through site-directed mutagenesis for glutamate (E988 for ABC2, and E989 for ABC3) and histidine (H1020 for ABC2, and H1021 for ABC3), we provided the evidence that glutamate was essential for the activity of ABC2 and ABC3 transporters, with ATP most likely to be hydrolyzed by a catalytic carboxylate mechanism. Conclusions Here, we demonstrated that transporter engineering through expression of heterologous efflux pumps led to significantly improved tolerance against alkane biofuels in S. cerevisiae. We believe that our results laid the groundwork for developing robust alkane-producing yeast cells through transporter engineering, which will greatly aid in next-generation alkane biofuel production and recovery. PMID:23402697

  11. Catalytic conversion of light alkanes - phase V. Topical report, February 1993--October 1994

    SciTech Connect

    NONE

    1998-12-31

    We have made excellent progress toward a practical route from field butanes to MTBE, the oxygenate of choice for high-octane, clean-burning, environmentally acceptable reformulated gasoline. We have evaluated two proprietary process possibilities with a potential commercial partner and have conducted a joint catalyst evaluation program. The first of the two potential processes considered during the past quarter utilizes a two-step route from isobutane to tert-butyl alcohol, TBA. Not only is TBA an intermediate for MTBE production but is equally applicable for ETBE-an oxygenate which utilizes renewable ethanol in its` manufacture. In the two-step process, isobutane is oxidized in a non-catalytic reaction to a roughly equal mixture of TBA and tert-butyl hydroperoxide. TBHP, eq. 1. We have developed an inexpensive new catalyst system based on an electron-deficient macrocyclic metal complex that selectively converts TBHP to TBA, eq. 2, and meets or exceeds all of the process criteria that we have set.

  12. Assessment of the GECKO-A modeling tool using chamber observations for C12 alkanes

    NASA Astrophysics Data System (ADS)

    Aumont, B.; La, S.; Ouzebidour, F.; Valorso, R.; Mouchel-Vallon, C.; Camredon, M.; Lee-Taylor, J. M.; Hodzic, A.; Madronich, S.; Yee, L. D.; Loza, C. L.; Craven, J. S.; Zhang, X.; Seinfeld, J.

    2013-12-01

    Secondary Organic Aerosol (SOA) production and ageing is the result of atmospheric oxidation processes leading to the progressive formation of organic species with higher oxidation state and lower volatility. Explicit chemical mechanisms reflect our understanding of these multigenerational oxidation steps. Major uncertainties remain concerning the processes leading to SOA formation and the development, assessment and improvement of such explicit schemes is therefore a key issue. The development of explicit mechanism to describe the oxidation of long chain hydrocarbons is however a challenge. Indeed, explicit oxidation schemes involve a large number of reactions and secondary organic species, far exceeding the size of chemical schemes that can be written manually. The chemical mechanism generator GECKO-A (Generator for Explicit Chemistry and Kinetics of Organics in the Atmosphere) is a computer program designed to overcome this difficulty. GECKO-A generates gas phase oxidation schemes according to a prescribed protocol assigning reaction pathways and kinetics data on the basis of experimental data and structure-activity relationships. In this study, we examine the ability of the generated schemes to explain SOA formation observed in the Caltech Environmental Chambers from various C12 alkane isomers and under high NOx and low NOx conditions. First results show that the model overestimates both the SOA yields and the O/C ratios. Various sensitivity tests are performed to explore processes that might be responsible for these disagreements.

  13. Modeling SOA formation from the oxidation of intermediate volatility n-alkanes

    NASA Astrophysics Data System (ADS)

    Aumont, B.; Valorso, R.; Mouchel-Vallon, C.; Camredon, M.; Lee-Taylor, J.; Madronich, S.

    2012-06-01

    The chemical mechanism leading to SOA formation and ageing is expected to be a multigenerational process, i.e. a successive formation of organic compounds with higher oxidation degree and lower vapor pressure. This process is here investigated with the explicit oxidation model GECKO-A (Generator of Explicit Chemistry and Kinetics of Organics in the Atmosphere). Gas phase oxidation schemes are generated for the C8-C24 series of n-alkanes. Simulations are conducted to explore the time evolution of organic compounds and the behavior of secondary organic aerosol (SOA) formation for various preexisting organic aerosol concentration (COA). As expected, simulation results show that (i) SOA yield increases with the carbon chain length of the parent hydrocarbon, (ii) SOA yield decreases with decreasing COA, (iii) SOA production rates increase with increasing COA and (iv) the number of oxidation steps (i.e. generations) needed to describe SOA formation and evolution grows when COA decreases. The simulated oxidative trajectories are examined in a two dimensional space defined by the mean carbon oxidation state and the volatility. Most SOA contributors are not oxidized enough to be categorized as highly oxygenated organic aerosols (OOA) but reduced enough to be categorized as hydrocarbon like organic aerosols (HOA), suggesting that OOA may underestimate SOA. Results show that the model is unable to produce highly oxygenated aerosols (OOA) with large yields. The limitations of the model are discussed.

  14. Modeling SOA formation from the oxidation of intermediate volatility n-alkanes

    NASA Astrophysics Data System (ADS)

    Aumont, B.; Valorso, R.; Mouchel-Vallon, C.; Camredon, M.; Lee-Taylor, J.; Madronich, S.

    2012-08-01

    The chemical mechanism leading to SOA formation and ageing is expected to be a multigenerational process, i.e. a successive formation of organic compounds with higher oxidation degree and lower vapor pressure. This process is here investigated with the explicit oxidation model GECKO-A (Generator of Explicit Chemistry and Kinetics of Organics in the Atmosphere). Gas phase oxidation schemes are generated for the C8-C24 series of n-alkanes. Simulations are conducted to explore the time evolution of organic compounds and the behavior of secondary organic aerosol (SOA) formation for various preexisting organic aerosol concentration (COA). As expected, simulation results show that (i) SOA yield increases with the carbon chain length of the parent hydrocarbon, (ii) SOA yield decreases with decreasing COA, (iii) SOA production rates increase with increasing COA and (iv) the number of oxidation steps (i.e. generations) needed to describe SOA formation and evolution grows when COA decreases. The simulated oxidative trajectories are examined in a two dimensional space defined by the mean carbon oxidation state and the volatility. Most SOA contributors are not oxidized enough to be categorized as highly oxygenated organic aerosols (OOA) but reduced enough to be categorized as hydrocarbon like organic aerosols (HOA), suggesting that OOA may underestimate SOA. Results show that the model is unable to produce highly oxygenated aerosols (OOA) with large yields. The limitations of the model are discussed.

  15. Preliminary assessment of halogenated alkanes as vapor-phase tracers

    SciTech Connect

    Adams, Michael C.; Moore, Joseph N.; Hirtz, Paul

    1991-01-01

    New tracers are needed to evaluate the efficiency of injection strategies in vapor-dominated environments. One group of compounds that seems to meet the requirements for vapor-phase tracing are the halogenated alkanes (HCFCs). HCFCs are generally nontoxic, and extrapolation of tabulated thermodynamic data indicate that they will be thermally stable and nonreactive in a geothermal environment. The solubilities and stabilities of these compounds, which form several homologous series, vary according to the substituent ratios of fluorine, chlorine, and hydrogen. Laboratory and field tests that will further define the suitability of HCFCs as vapor-phase tracers are under way.

  16. for Undergraduate CHEMISTRY MAJORS

    E-print Network

    Stuart, Steven J.

    and Petroleum Chemistry, Organic Chemistry, Physical Chemistry, Polymer Chemistry, Pulp and Paper Chemistry, RHANDBOOK for Undergraduate CHEMISTRY MAJORS DEPARTMENT OF CHEMISTRY Fall 2010 #12;#12;TABLE OF CONTENTS A Career in Chemistry - What It Means ___________________________________________ 4 What do

  17. Energy Conversion & Storage Program, 1993 annual report

    SciTech Connect

    Cairns, E.J.

    1994-06-01

    The Energy Conversion and Storage Program applies chemistry and materials science principles to solve problems in: production of new synthetic fuels; development of high-performance rechargeable batteries and fuel cells; development of high-efficiency thermochemical processes for energy conversion; characterization of complex chemical processes and chemical species; and the study and application of novel materials for energy conversion and transmission. Projects focus on transport-process principles, chemical kinetics, thermodynamics, chemical kinetics, thermodynamics, separation processes, organic and physical chemistry, novel materials, and advanced methods of analysis.

  18. Effect of alkane chain length and counterion on the freezing transition of cationic surfactant adsorbed film at alkane mixture - water interfaces.

    PubMed

    Tokiwa, Yuhei; Sakamoto, Hiroyasu; Takiue, Takanori; Aratono, Makoto; Matsubara, Hiroki

    2015-05-21

    Penetration of alkane molecules into the adsorbed film gives rise to a surface freezing transition of cationic surfactant at the alkane-water interface. To examine the effect of the alkane chain length and counterion on the surface freezing, we employed interfacial tensiometry and ellipsometry to study the interface of cetyltrimethylammonium bromide and cetyltrimethylammonium chloride aqueous solutions against dodecane, tetradecane, hexadecane, and their mixtures. Applying theoretical equations to the experimental results obtained, we found that the alkane molecules that have the same chain length as the surfactant adsorb preferentially into the surface freezing film. Furthermore, we demonstrated that the freezing transition temperature of cationic surfactant adsorbed film was independent of the kind of counterion. PMID:25932500

  19. Polyoxometalates as homogeneous oxidatively resistant catalysts for difficult selective organic oxidations. Functionalization of alkanes

    Microsoft Academic Search

    C. L. Hill; R. B. Jr. Brown; R. F. Renneke

    1987-01-01

    Few problems have been as frequently addressed in the chemical literature in the last few years as the selective activation and\\/or functionalization of alkanes. In addition to the substantial number of studies involving alkane C-H bond cleavage processes in the gas phase or in solid matrices and theoretical work, there has been an explosion of knowledge with respect to systems

  20. Geomicrobiological linkages between short-chain alkane consumption and sulfate reduction rates in seep sediments

    PubMed Central

    Bose, Arpita; Rogers, Daniel R.; Adams, Melissa M.; Joye, Samantha B.; Girguis, Peter R.

    2013-01-01

    Marine hydrocarbon seeps are ecosystems that are rich in methane, and, in some cases, short-chain (C2C5) and longer alkanes. C2C4 alkanes such as ethane, propane, and butane can be significant components of seeping fluids. Some sulfate-reducing microbes oxidize short-chain alkanes anaerobically, and may play an important role in both the competition for sulfate and the local carbon budget. To better understand the anaerobic oxidation of short-chain n-alkanes coupled with sulfate-reduction, hydrocarbon-rich sediments from the Gulf of Mexico (GoM) were amended with artificial, sulfate-replete seawater and one of four n-alkanes (C1C4) then incubated under strict anaerobic conditions. Measured rates of alkane oxidation and sulfate reduction closely follow stoichiometric predictions that assume the complete oxidation of alkanes to CO2 (though other sinks for alkane carbon likely exist). Changes in the ?13C of all the alkanes in the reactors show enrichment over the course of the incubation, with the C3 and C4 incubations showing the greatest enrichment (4.4 and 4.5, respectively). The concurrent depletion in the ?13C of dissolved inorganic carbon (DIC) implies a transfer of carbon from the alkane to the DIC pool (?3.5 and ?6.7 for C3 and C4 incubations, respectively). Microbial community analyses reveal that certain members of the class Deltaproteobacteria are selectively enriched as the incubations degrade C1C4 alkanes. Phylogenetic analyses indicate that distinct phylotypes are enriched in the ethane reactors, while phylotypes in the propane and butane reactors align with previously identified C3C4 alkane-oxidizing sulfate-reducers. These data further constrain the potential influence of alkane oxidation on sulfate reduction rates (SRRs) in cold hydrocarbon-rich sediments, provide insight into their contribution to local carbon cycling, and illustrate the extent to which short-chain alkanes can serve as electron donors and govern microbial community composition and density. PMID:24376442

  1. Delayering of Intermediate-Length Alkanes Adsorbed on Solid Surfaces

    NASA Astrophysics Data System (ADS)

    Taub, H.; Bai, M.; Diama, A.; Knorr, K.; Volkmann, U. G.; Hansen, F. Y.

    2007-03-01

    We have recently discovered that a film of the intermediate-length alkane, dotriacontane (n-C32H66 or C32) does not completely wet SiO2 and highly oriented graphite surfaces on a nanometer length scale. In a narrow temperature range near the bulk melting point Tb, we observe a single layer of C32 molecules oriented with their long axis perpendicular to the surface. On heating just above Tb, these molecules undergo a delayering transition to three-dimensional droplets that remain present up to their evaporation point. Here we report noncontact Atomic Force Microscopy and synchrotron x-ray measurements indicating that a similar delayering transition occurs for films of other intermediate-length alkanes: C24, C25, C30, and C36 deposited from solution onto a SiO2 surface. These results raise a number of interesting questions including whether the delayering transition is driven by conformational changes in the molecules and what implications the nonwetting behavior may have for lubricating nanoscale devices. M. Bai et al., cond-mat/0611497.

  2. 40 CFR 721.10178 - Distillates (Fischer-Tropsch), hydroisomerized middle, C10-13-branched alkane fraction.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ...C10-13-branched alkane fraction. 721.10178 Section...ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) TOXIC SUBSTANCES CONTROL...C10-13-branched alkane fraction. (a) Chemical substance...C10-13-branched alkane fraction (PMN P-04-319;...

  3. 40 CFR 721.10178 - Distillates (Fischer-Tropsch), hydroisomerized middle, C10-13-branched alkane fraction.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ...C10-13-branched alkane fraction. 721.10178 Section...ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) TOXIC SUBSTANCES CONTROL...C10-13-branched alkane fraction. (a) Chemical substance...C10-13-branched alkane fraction (PMN P-04-319;...

  4. Conversion, Fragmentation,

    E-print Network

    the tide?" The discussions over the two days indicate that we are searching for ways to both accommodate the rising tide and shorten its reach. And that both are necessary. Page 4 | Forestland Conversion

  5. CHEMISTRY 521 GRADUATE PHYSICAL CHEMISTRY

    E-print Network

    Findley, Gary L.

    CHEMISTRY 521 GRADUATE PHYSICAL CHEMISTRY Fall Term, 1999 INSTRUCTOR INFORMATION Instructor: Dr@alpha.nlu.edu URL: http://www.nlu.edu/chemistry/findley/findley.html COURSE Content: A review of selected topics in Physical Chemistry. Goals/ Objectives: Introduction to quantum mechanics. Topics covered include

  6. CHEMISTRY 320 PHYSICAL CHEMISTRY I

    E-print Network

    Findley, Gary L.

    CHEMISTRY 320 PHYSICAL CHEMISTRY I Fall 2009 9:00 am - 10:30 am, MW CNSB 211 INSTRUCTOR INFORMATION of the physical principles of chemistry. Goals/ Objectives: CHEM 320 presents chemical principles from" or better in CHEM 108; PHYS 208; MATH 132. Text: Physical Chemistry, P. Atkins and J. de Paula, 8th ed. (W

  7. Environmental Chemistry II (Atmospheric Chemistry)

    E-print Network

    Dibble, Theodore

    SYLLABUS FOR Environmental Chemistry II (Atmospheric Chemistry) FCH 511 Fall 2013 Theodore S. Dibble Professor of Chemistry 421 Jahn Laboratory Syracuse, NY 13210 Phone: (315) 470-6596 Fax: (315) 470 Seinfeld, J. H. and Pandis, S. N. Atmospheric Chemistry and Physics: From Air Pollution to Climate Change

  8. CHEMISTRY 322 PHYSICAL CHEMISTRY II

    E-print Network

    Findley, Gary L.

    CHEMISTRY 322 PHYSICAL CHEMISTRY II Spring 2010 10:00 am - 11:30 am, MW CNSB 211 INSTRUCTOR interpretations of the physical principles of chemistry. Goals/ Objectives: CHEM 322, which is a continuation of CHEM 320, focuses of the quantum theoretical foundations of modern chemistry. Topics covered include

  9. Chemistry 419 PHYSICAL CHEMISTRY LABORATORY

    E-print Network

    Richmond, Geraldine L.

    Chemistry 419 PHYSICAL CHEMISTRY LABORATORY Spring, 2008 Lecture/Discussion 1:00 Tuesday, Brittney Young Required Text: Chemistry 419 - Physical Chemistry Laboratory - University Bookstore. Students are required to perform seven laboratories from among those offered this quarter. The first week

  10. Energy Conversion and Storage Program. 1990 annual report

    Microsoft Academic Search

    Cairns

    1992-01-01

    The Energy Conversion and Storage Program applies chemistry and materials science principles to solve problems in (1) production of new synthetic fuels, (2) development of high-performance rechargeable batteries and fuel cells, (3) development of advanced thermochemical processes for energy conversion, (4) characterization of complex chemical processes, and (5) application of novel materials for energy conversion and transmission. Projects focus on

  11. Green Chemistry

    NSDL National Science Digital Library

    2002-01-01

    This special feature page from the American Chemical Society (ACS) showcases the up-and-coming field of "green chemistry," that is, the development of chemical products and processes that eliminate or reduce the use and generation of hazardous substances. A list of principles behind green chemistry, a searchable bibliography of green chemistry references, green chemistry links (including conferences), and an online preview of the ACS-published book Real-World Cases in Green Chemistry are all found at the site. Five video clips on green chemistry from the standpoint of academia, industry, and small business are also featured (Windows Media Player). This page comes from ACS's Green Chemistry Project, a three-year educational project to develop and disseminate green chemistry educational materials for graduate and undergraduate chemistry students. Check back often for updates.

  12. MIR and NIR group spectra of n-alkanes and 1-chloroalkanes

    NASA Astrophysics Data System (ADS)

    Kwa?niewicz, Micha?; Czarnecki, Miros?aw A.

    2015-05-01

    Numerous attempts were undertaken to resolve the absorption originating from different parts of alkanes. The separation of the contributions from the terminal and midchain methylene units was observed only in the spectra of solid alkanes at low temperatures. On the other hand, for liquid alkanes this effect was not reported as yet. In this study, ATR-IR, Raman and NIR spectra of eight n-alkanes and seven 1-chloroalkanes in the liquid phase were measured from 1000 to 12,000 cm-1. The spectra were analyzed by using two-dimensional (2D) correlation approach and chemometrics methods. It was shown that in 2D asynchronous contour plots, constructed from the spectra of n-alkanes and 1-chloroalkanes, the methylene band was resolved into two components. These two components were assigned to the terminal and midchain methylene groups. For the first time, the contributions from these two molecular fragments were resolved in the spectra of liquid n-alkanes and 1-chloroalkanes. MCR-ALS resolved these spectra into two components that were assigned to the ethyl and midchain methylene groups. These components represent the group spectra that can be used for assignment, spectral analysis and prediction of unknown spectra. The spectral prediction based on the group spectra provides very good results for n-alkanes, especially in the first and second overtone regions.

  13. Enrichment and Characterization of a Psychrotolerant Consortium Degrading Crude Oil Alkanes Under Methanogenic Conditions.

    PubMed

    Ding, Chen; Ma, Tingting; Hu, Anyi; Dai, Lirong; He, Qiao; Cheng, Lei; Zhang, Hui

    2015-08-01

    Anaerobic alkane degradation via methanogenesis has been intensively studied under mesophilic and thermophilic conditions. While there is a paucity of information on the ability and composition of anaerobic alkane-degrading microbial communities under low temperature conditions. In this study, we investigated the ability of consortium Y15, enriched from Shengli oilfield, to degrade hydrocarbons under different temperature conditions (5-35C). The consortium could use hexadecane over a low temperature range (15-30C). No growth was detected below 10C and above 35C, indicating the presence of cold-tolerant species capable of alkane degradation. The preferential degradation of short chain n-alkanes from crude oil was observed by this consortium. The structure and dynamics of the microbial communities were examined using terminal restriction fragment length polymorphism (T-RFLP) fingerprinting and Sanger sequencing of 16S rRNA genes. The core archaeal communities were mainly composed of aceticlastic Methanosaeta spp. Syntrophaceae-related microorganisms were always detected during consecutive transfers and dominated the bacterial communities, sharing 94-96% sequence similarity with Smithella propionica strain LYP(T). Phylogenetic analysis of Syntrophaceae-related clones in diverse methanogenic alkane-degrading cultures revealed that most of them were clustered into three sublineages. Syntrophaceae clones retrieved from this study were mainly clustered into sublineage I, which may represent psychrotolerant, syntrophic alkane degraders. These results indicate the wide geographic distribution and ecological function of syntrophic alkane degraders. PMID:25783218

  14. Introduction to Solar Photon Conversion

    SciTech Connect

    Nozik, Arthur J; Miller, John

    2010-01-01

    This Thematic Issue on Solar Photon Conversion will provide a review by leading researchers on the present status and prognosis of the science and technology of direct solar photoconversion to electricity and fuels. The topics covered include advanced and novel concepts for low-cost photovoltaic (PV) energy based on chemistry (dye-sensitized photoelectrodes, organic and molecular PV, multiple exciton generation in quantum dots, singlet fission), solar water splitting, redox catalysis for water oxidation and reduction, the role of nanoscience and nanocrystals in solar photoconversion, photoelectrochemical energy conversion, and photoinduced electron transfer.

  15. Biosynthetic origin of the saw-toothed profile in delta(13)C and delta(2)H of n-alkanes and systematic isotopic differences between n-, iso- and anteiso-alkanes in leaf waxes of land plants.

    PubMed

    Zhou, Youping; Grice, Kliti; Stuart-Williams, Hilary; Farquhar, Graham D; Hocart, Charles H; Lu, Hong; Liu, Weiguo

    2010-03-01

    The n-fatty acids containing an even number of carbons (ECN-n-FAs) in higher plants are biosynthesised by repetitive addition of a two carbon unit from malonyl-ACP. The n-alkanes containing an odd number of carbon atoms (OCN-n-alkanes) are generally formed by the decarboxylation of ECN-n-FAs, but it is unknown how the less abundant even-carbon-numbered alkanes (ECN-n-alkanes) are biosynthesised in higher plants. There is a distinctive compositional pattern of incorporation of stable carbon ((13)C) and hydrogen ((2)H) isotopes in co-existing ECN- and OCN-n-alkanes in leaves of higher plants, such that the OCN n-alkanes are relatively enriched in (13)C but relatively depleted in (2)H against the ECN-n-alkanes. This is consistent with the OCN-n-fatty acids having a propionate precursor which is derived from reduction of pyruvate. A tentative pathway is presented with propionate produced by enzymatic reduction of pyruvate which is then thio-esterified with CoSH (coenzyme A thiol) in the chloroplast to form the terminal precursor molecule propionyl-CoA. This is then repetitively extended/elongated with the 2-carbon unit from malonyl-ACP to form the long chain OCN-n-fatty acids. The anteiso- and iso-alkanes in Nicotiana tabacum leaf waxes have previously been found to be systematically enriched in (13)C compared with the n-alkanes by Grice et al. (2008). This is consistent with the isotopic composition of their putative respective precursors (pyruvate as precursor for n-alkanes, valine for iso-alkanes and isoleucine for anteiso-alkanes). The current study complements that of Grice et al. (2008) and looks at the distribution of hydrogen isotopes. The n-alkanes were found to be more enriched in deuterium ((2)H) than the iso-alkanes which in turn were more enriched than the anteiso-alkanes. We propose therefore that the depletion of (2)H in the iso-alkanes, relative to the n-alkanes is the consequence of accepting highly (2)H-depleted hydrogen atoms from NADPH during their biosynthesis. The anteiso-alkanes are further depleted again because there are three NADPH-derived hydrogen atoms in their precursor isoleucine, as compared with only one NADPH-derived hydrogen in valine, the precursor of the iso-alkanes. PMID:20056262

  16. ENVIRONMENTAL CHEMISTRY

    EPA Science Inventory

    Environmental chemistry is applied to estimating the exposure of ecosystems and humans to various chemical environmental stressors. Among the stressors of concern are mercury, pesticides, and arsenic. Advanced analytical chemistry techniques are used to measure these stressors ...

  17. Chemistry Notes

    ERIC Educational Resources Information Center

    School Science Review, 1976

    1976-01-01

    Described are eight chemistry experiments and demonstrations applicable to introductory chemistry courses. Activities include: measure of lattice enthalpy, Le Chatelier's principle, decarboxylation of soap, use of pocket calculators in pH measurement, and making nylon. (SL)

  18. Chemistry Notes.

    ERIC Educational Resources Information Center

    School Science Review, 1978

    1978-01-01

    Describes experiments, demonstrations, activities and ideas relating to various fields of chemistry to be used in chemistry courses of secondary schools. Three experiments concerning differential thermal analysis are among these notes presented. (HM)

  19. Hydrogen isotope exchange between n-alkanes and water under hydrothermal conditions

    NASA Astrophysics Data System (ADS)

    Reeves, Eoghan P.; Seewald, Jeffrey S.; Sylva, Sean P.

    2012-01-01

    To investigate the extent of hydrogen isotope (2H and 1H) exchange between hydrocarbons and water under hydrothermal conditions, we performed experiments heating C1-C5n-alkanes in aqueous solutions of varying initial 2H/1H ratios in the presence of a pyrite-pyrrhotite-magnetite redox buffer at 323 C and 35-36 MPa. Extensive and reversible incorporation of water-derived hydrogen into C2-C5n-alkanes was observed on timescales of months. In contrast, comparatively minor exchange was observed for CH4. Isotopic exchange is facilitated by reversible equilibration of n-alkanes and their corresponding n-alkenes with H2 derived from the disproportionation of water. Rates of ?2H variation in C3+n-alkanes decreased with time, a trend that is consistent with an asymptotic approach to steady state isotopic compositions regulated by alkane-water isotopic equilibrium. Substantially slower ?2H variation was observed for ethane relative to C3-C5n-alkanes, suggesting that the greater stability of C3+ alkenes and isomerization reactions may dramatically enhance rates of 2H/1H exchange in C3+n-alkanes. Thus, in reducing aqueous environments, reversible reaction of alkanes and their corresponding alkenes facilitates rapid 2H/1H exchange between water and alkyl-bound hydrogen on relatively short geological timescales at elevated temperatures and pressures. The proximity of some thermogenic and purported abiogenic alkane ?2H values to those predicted for equilibrium 2H/1H fractionation with ambient water suggests that this process may regulate the ?2H signatures of some naturally occurring hydrocarbons.

  20. Biodegradation of Variable-Chain-Length Alkanes at Low Temperatures by a Psychrotrophic Rhodococcus sp.

    PubMed Central

    Whyte, Lyle G.; Hawari, Jalal; Zhou, Edward; Bourbonnire, Luc; Inniss, William E.; Greer, Charles W.

    1998-01-01

    The psychrotroph Rhodococcus sp. strain Q15 was examined for its ability to degrade individual n-alkanes and diesel fuel at low temperatures, and its alkane catabolic pathway was investigated by biochemical and genetic techniques. At 0 and 5C, Q15 mineralized the short-chain alkanes dodecane and hexadecane to a greater extent than that observed for the long-chain alkanes octacosane and dotriacontane. Q15 utilized a broad range of aliphatics (C10 to C21 alkanes, branched alkanes, and a substituted cyclohexane) present in diesel fuel at 5C. Mineralization of hexadecane at 5C was significantly greater in both hydrocarbon-contaminated and pristine soil microcosms seeded with Q15 cells than in uninoculated control soil microcosms. The detection of hexadecane and dodecane metabolic intermediates (1-hexadecanol and 2-hexadecanol and 1-dodecanol and 2-dodecanone, respectively) by solid-phase microextractiongas chromatography-mass spectrometry and the utilization of potential metabolic intermediates indicated that Q15 oxidizes alkanes by both the terminal oxidation pathway and the subterminal oxidation pathway. Genetic characterization by PCR and nucleotide sequence analysis indicated that Q15 possesses an aliphatic aldehyde dehydrogenase gene highly homologous to the Rhodococcus erythropolis thcA gene. Rhodococcus sp. strain Q15 possessed two large plasmids of approximately 90 and 115 kb (shown to mediate Cd resistance) which were not required for alkane mineralization, although the 90-kb plasmid enhanced mineralization of some alkanes and growth on diesel oil at both 5 and 25C. PMID:9647833

  1. Equilibrium thermophysical properties of alkanes at very high temperatures

    SciTech Connect

    Arunachalam, C.; Bozkurt, B.; Eubank, P.T. [Texas A and M Univ., College Station, TX (United States). Dept. of Chemical Engineering] [Texas A and M Univ., College Station, TX (United States). Dept. of Chemical Engineering

    1996-01-01

    In order to perform calculations for thermal plasmas, sparks, and arcs, as in the thermal arc and electrical discharge machining (EDM) processes, thermophysical properties, such as the density, enthalpy, and heat capacity, of the original ambient dielectric liquid are required at very high temperatures and often pressures in the plasma state. A statistical model has been developed to provide these properties. At high temperatures, these hydrocarbons undergo a series of reactions to first dissociate and then to ionize to produce a plasma. The partition functions of each of the species generated are calculated and sued to determine the equilibrium mole fractions or particle fractions of each constituent of the resultant plasma. Only the hydrogen-to-carbon ratio matters so mixtures of alkanes can also be used. Specifically, tables of particles fractions, densities, enthalpies, and specific heat capacities are provided for methane and for hexadecane to 60,000 K and 10 kbar.

  2. Metric Conversions

    NSDL National Science Digital Library

    The North Carolina Community College System BioNetwork's interactive eLearning tools (IETs) are reusable chunks of training that can be deployed in a variety of courses or training programs. IETs are designed to enhance, not replace hands-on training. Learners are able to enter a hands-on lab experience better prepared and more confident. This particular IET delves into metric conversions with this "excellent tool for refreshing your knowledge of dimensional analysis, English-to-Metric, Metric-to-English, and Metric-to-Metric conversions."

  3. Photochemical dimerization and functionalization of alkanes, ethers, primary and secondary alcohols, phosphine oxides and silanes

    DOEpatents

    Crabtree, R.H.; Brown, S.H.

    1989-10-17

    The space-time yield and/or the selectivity of the photochemical dimerization of alkanes, ethers, primary and secondary alcohols, phosphine oxides and primary, secondary and tertiary silanes with Hg and U.V. light is enhanced by refluxing the substrate in the irradiated reaction zone at a temperature at which the dimer product condenses and remains condensed promptly upon its formation. Cross-dimerization of the alkanes, ethers and silanes with primary alcohols is disclosed, as is the functionalization to aldehydes of the alkanes with carbon monoxide.

  4. Forensic Chemistry

    Microsoft Academic Search

    Suzanne Bell

    2009-01-01

    Forensic chemistry is unique among chemical sciences in that its research, practice, and presentation must meet the needs of both the scientific and the legal communities. As such, forensic chemistry research is applied and derivative by nature and design, and it emphasizes metrology (the science of measurement) and validation. Forensic chemistry has moved away from its analytical roots and is

  5. Biochemistry chemistry &

    E-print Network

    Morgan, Stephen L.

    Biochemistry chemistry & A n A ly t i c A l B i o l o g i c A l i n o r g A n i c o r g A n i c P h of South Carolina..........................1 Department of Chemistry and Biochemistry....2 The Graduate Program in Chemistry and Biochemistry.........................................................3 Ph

  6. Chemistry Notes.

    ERIC Educational Resources Information Center

    School Science Review, 1982

    1982-01-01

    Presents background information, laboratory procedures, classroom materials/activities, and experiments for chemistry. Topics include superheavy elements, polarizing power and chemistry of alkali metals, particulate carbon from combustion, tips for the chemistry laboratory, interesting/colorful experiments, behavior of bismuth (III) iodine, and

  7. Chemistry Links

    NSDL National Science Digital Library

    Charnine, Michael

    This compiled site contains titles and links to over 40 sites, journal articles, course and tutorial materials, simulations, batteries, and other resources. Definitions of chemistry, theoretical chemistry, organic, physical and nuclear chemistry are integrated with the links to outside materials. A number of useful keywords are included to help users navigate the materials.

  8. To Form a Favorable Idea of Chemistry

    ERIC Educational Resources Information Center

    Heikkinen, Henry W.

    2010-01-01

    "To confess the truth, Mrs. B., I am not disposed to form a very favorable idea of chemistry, nor do I expect to derive much entertainment from it." That 200-year-old statement by Caroline to Mrs. Bryan, her teacher, appeared on the first page of Jane Marcet's pioneering secondary school textbook, "Conversations on Chemistry". It was published 17

  9. The Doctorate in Chemistry. Carnegie Essays on the Doctorate: Chemistry.

    ERIC Educational Resources Information Center

    Breslow, Ronald

    The Carnegie Foundation commissioned a collection of essays as part of the Carnegie Initiative on the Doctorate (CID). Essays and essayists represent six disciplines that are part of the CID: chemistry, education, English, history, mathematics, and neuroscience. Intended to engender conversation about the conceptual foundation of doctoral

  10. Conversational Tamil.

    ERIC Educational Resources Information Center

    Beinstein, Judith; And Others

    The purpose of this text is to develop conversational skills in Tamil. It is to be used as a review of what has been learned in class and not as a teaching device. The language materials consist of four types of language learning activities. The unit microwave cycle divides the learning process into two basic phases. The first phase involves

  11. Conversational Telugu.

    ERIC Educational Resources Information Center

    Beinstein, Judith; And Others

    The purpose of this text is to develop elementary conversational skills in Telugu. The language materials consist of four types of language learning activities. The first, and most predominant, is the unit microwave cycle. These cycles divide the learning process into two basic phases, the first of which involves mimicry, memorization, and

  12. Forensic Chemistry

    NASA Astrophysics Data System (ADS)

    Bell, Suzanne

    2009-07-01

    Forensic chemistry is unique among chemical sciences in that its research, practice, and presentation must meet the needs of both the scientific and the legal communities. As such, forensic chemistry research is applied and derivative by nature and design, and it emphasizes metrology (the science of measurement) and validation. Forensic chemistry has moved away from its analytical roots and is incorporating a broader spectrum of chemical sciences. Existing forensic practices are being revisited as the purview of forensic chemistry extends outward from drug analysis and toxicology into such diverse areas as combustion chemistry, materials science, and pattern evidence.

  13. Computational Chemistry for Chemistry Educators

    NSDL National Science Digital Library

    Shodor Computational Science Institute

    This is a 15-session course on the technologies, techniques, and tools of computational chemistry. By using the same computational tools as research computational chemists, educators will have the opportunity to study chemistry in a manner very different than traditional teaching and education in chemistry.

  14. 148 Chemistry/Chinese Chemistry 347 (3)--Advanced Organic Chemistry

    E-print Network

    Dresden, Gregory

    ,organometalliccatalyticprocesses,andsolid statechemistry.Uffelman. Spring 2008 and alternate years Chemistry 365 (3)--Advanced Physical Chemistry148 Chemistry/Chinese Chemistry 347 (3)--Advanced Organic Chemistry Prerequisite: Chemistry 242,syntheticmethodology,mod- ernsyntheticreactions,protectinggroups,naturalprod- uctssynthesis,andcombinatorialchemistry.France. Spring Chemistry

  15. Flow reactor studies of non-equilibrium plasma-assisted oxidation of n-alkanes.

    PubMed

    Tsolas, Nicholas; Lee, Jong Guen; Yetter, Richard A

    2015-08-13

    The oxidation of n-alkanes (C1-C7) has been studied with and without the effects of a nanosecond, non-equilibrium plasma discharge at 1?atm pressure from 420 to 1250?K. Experiments have been performed under nearly isothermal conditions in a flow reactor, where reactive mixtures are diluted in Ar to minimize temperature changes from chemical reactions. Sample extraction performed at the exit of the reactor captures product and intermediate species and stores them in a multi-position valve for subsequent identification and quantification using gas chromatography. By fixing the flow rate in the reactor and varying the temperature, reactivity maps for the oxidation of fuels are achieved. Considering all the fuels studied, fuel consumption under the effects of the plasma is shown to have been enhanced significantly, particularly for the low-temperature regime (T<800?K). In fact, multiple transitions in the rates of fuel consumption are observed depending on fuel with the emergence of a negative-temperature-coefficient regime. For all fuels, the temperature for the transition into the high-temperature chemistry is lowered as a consequence of the plasma being able to increase the rate of fuel consumption. Using a phenomenological interpretation of the intermediate species formed, it can be shown that the active particles produced from the plasma enhance alkyl radical formation at all temperatures and enable low-temperature chain branching for fuels C3 and greater. The significance of this result demonstrates that the plasma provides an opportunity for low-temperature chain branching to occur at reduced pressures, which is typically observed at elevated pressures in thermal induced systems. PMID:26170423

  16. Oxidative dehydrogenation of C2-C4 alkanes into alkenes: Conventional catalytic systems and microwave catalysis

    NASA Astrophysics Data System (ADS)

    Kustov, L. M.; Kucherov, A. V.; Finashina, E. D.

    2013-03-01

    Catalytic systems for the nonoxidative or oxidative dehydrogenation of C2-C4 alkanes into the respective alkenes are considered. Scanty data concerning microwave activation of these processes and the potential and advantages of microwave versus conventional technologies are analyzed.

  17. Draft Genome Sequence of the Versatile Alkane-Degrading Bacterium Aquabacterium sp. Strain NJ1

    PubMed Central

    Shiwa, Yuh; Yoshikawa, Hirofumi; Zylstra, Gerben J.

    2014-01-01

    The draft genome sequence of a soil bacterium, Aquabacterium sp. strain NJ1, capable of utilizing both liquid and solid alkanes, was deciphered. This is the first report of an Aquabacterium genome sequence. PMID:25477416

  18. Experimental proof for resonant diffusion of normal alkanes in LTL and ZSM-12 zeolites

    E-print Network

    Yoo, K; Smirniotis, P G

    2015-01-01

    The intra-crystalline diffusion of normal alkanes in LTL and ZSM-12 zeolite was experimentally studied via gravimetric measurements performed at different temperatures. A periodic dependence of the diffusion coefficient on the number of carbon atoms in alkane was detected, which is an experimental proof for resonant diffusion. The present observations were described on the base of the existing theory of the resonant diffusion and several important parameters of the alkane-zeolite interaction and zeolite vibrations were obtained. In the considered temperature region the diffusion coefficient follows the Arrhenius law with periodic dependences of the pre-exponential factor and activation energy on the number of carbon atoms in alkanes. A compensation effect of simultaneous increases of the pre-exponential factor and the activation energy was also established.

  19. Alkane Contamination Effects on PFPE Lubricant Bonding to a-CHx Overcoats

    E-print Network

    Gellman, Andrew J.

    Alkane Contamination Effects on PFPE Lubricant Bonding to a-CHx Overcoats Ryan Z. Lei and Andrew J, respectively, of the common disk lubricant Fomblin Zdol. Temperature-programmed desorption experiments were

  20. Effect of n-alkanes on lipid bilayers depending on headgroups.

    PubMed

    Hishida, Mafumi; Endo, Asami; Nakazawa, Koyomi; Yamamura, Yasuhisa; Saito, Kazuya

    2015-05-01

    Phase behavior and structural properties were examined for phospholipid bilayers having different headgroups (DMPC, DMPS and DMPE) with added n-alkanes to study effect of flexible additives. Change in the temperatures of main transition of the lipid/alkane mixtures against the length of added alkanes depends largely on the headgroup. Theoretical analysis of the change of the temperature of transition indicates that the headgroup dependence is dominantly originated in the strong dependence of total enthalpy on the headgroups. The results of X-ray diffraction show that the enthalpic stabilization due to enhanced packing of acyl chains of the lipid by alkanes in the gel phase causes the headgroup-dependent change in the phase transition behavior. The enhanced packing in the gel phase also leads to easy emergence of the subgel phase with very short relaxation time at room temperature in the DMPE-based bilayers. PMID:25957868

  1. Biodegradation of variable-chain-length n-alkanes in Rhodococcus opacus R7 and the involvement of an alkane hydroxylase system in the metabolism.

    PubMed

    Zampolli, Jessica; Collina, Elena; Lasagni, Marina; Di Gennaro, Patrizia

    2014-01-01

    Rhodococcus opacus R7 is a Gram-positive bacterium isolated from a polycyclic aromatic hydrocarbon contaminated soil for its versatile metabolism; indeed the strain is able to grow on naphthalene, o-xylene, and several long- and medium-chain n-alkanes. In this work we determined the degradation of n-alkanes in Rhodococcus opacus R7 in presence of n-dodecane (C12), n-hexadecane (C16), n-eicosane (C20), n-tetracosane (C24) and the metabolic pathway in presence of C12. The consumption rate of C12 was 88%, of C16 was 69%, of C20 was 51% and of C24 it was 78%. The decrement of the degradation rate seems to be correlated to the length of the aliphatic chain of these hydrocarbons. On the basis of the metabolic intermediates determined by the R7 growth on C12, our data indicated that R. opacus R7 metabolizes medium-chain n-alkanes by the primary alcohol formation. This represents a difference in comparison with other Rhodococcus strains, in which a mixture of the two alcohols was observed. By GC-MSD analysis we also identified the monocarboxylic acid, confirming the terminal oxidation. Moreover, the alkB gene cluster from R. opacus R7 was isolated and its involvement in the n-alkane degradation system was investigated by the cloning of this genomic region into a shuttle-vector E. coli-Rhodococcus to evaluate the alkane hydroxylase activity. Our results showed an increased biodegradation of C12 in the recombinant strain R. erythropolis AP (pTipQT1-alkR7) in comparison with the wild type strain R. erythropolis AP. These data supported the involvement of the alkB gene cluster in the n-alkane degradation in the R7 strain. PMID:25401074

  2. Measuring long chain alkanes in diesel engine exhaust by thermal desorption PTR-MS

    NASA Astrophysics Data System (ADS)

    Erickson, M. H.; Gueneron, M.; Jobson, B. T.

    2014-01-01

    A method using thermal desorption sampling and analysis by proton transfer reaction mass spectrometry (PTR-MS) to measure long chain alkanes (C12-C18) and other larger organics associated with diesel engine exhaust emissions is described. Long chain alkanes undergo dissociative proton transfer reactions forming a series of fragment ions with formula CnH2n+1. The PTR-MS is insensitive to n-alkanes less than C8 but displays an increasing sensitivity for larger alkanes. Fragment ion distribution and sensitivity is a function of drift conditions. At 80 Td the most abundant ion fragments from C10 to C16 n-alkanes were m/z 57, 71 and 85. The mass spectrum of gasoline and diesel fuel at 80 Td displayed ion group patterns that can be related to known fuel constituents, such as alkanes, alkylbenzenes and cycloalkanes, and other compound groups that are inferred from molecular weight distributions such as dihydronapthalenes and naphthenic monoaromatics. It is shown that thermal desorption sampling of gasoline and diesel engine exhausts at 80 Td allows for discrimination against volatile organic compounds, allowing for quantification of long chain alkanes from the abundance of CnH2n+1 fragment ions. The total abundance of long chain alkanes in diesel engine exhaust was measured to be similar to the total abundance of C1-C4 alkylbenzene compounds. The abundance patterns of compounds determined by thermal desorption sampling may allow for emission profiles to be developed to better quantify the relative contributions of diesel and gasoline exhaust emissions on organic compounds concentrations in urban air.

  3. The regularities in the interaction of alkanes with CO 2 on oxide catalysts

    Microsoft Academic Search

    O. V. Krylov; A. Kh. Mamedov; S. R. Mirzabekova

    1995-01-01

    Catalytic oxidation of C1-C7 alkanes by CO2 as a non-traditional oxidant was studied on oxide catalysts. The supported manganese oxide catalysts are the most active, selective and stable. Methane is converted mainly into synthesis gas. Ethane and propane give products of oxidative dehydrogenation. In the case of C4-C7 alkanes at first direct dehydrogenation takes place and after that reverse water

  4. The quantitative significance of Syntrophaceae and syntrophic partnerships in methanogenic degradation of crude oil alkanes

    PubMed Central

    Gray, N D; Sherry, A; Grant, R J; Rowan, A K; Hubert, C R J; Callbeck, C M; Aitken, C M; Jones, D M; Adams, J J; Larter, S R; Head, I M

    2011-01-01

    Libraries of 16S rRNA genes cloned from methanogenic oil degrading microcosms amended with North Sea crude oil and inoculated with estuarine sediment indicated that bacteria from the genera Smithella (Deltaproteobacteria, Syntrophaceace) and Marinobacter sp. (Gammaproteobacteria) were enriched during degradation. Growth yields and doubling times (36 days for both Smithella and Marinobacter) were determined using qPCR and quantitative data on alkanes, which were the predominant hydrocarbons degraded. The growth yield of the Smithella sp. [0.020 g(cell-C)/g(alkane-C)], assuming it utilized all alkanes removed was consistent with yields of bacteria that degrade hydrocarbons and other organic compounds in methanogenic consortia. Over 450 days of incubation predominance and exponential growth of Smithella was coincident with alkane removal and exponential accumulation of methane. This growth is consistent with Smithella's occurrence in near surface anoxic hydrocarbon degrading systems and their complete oxidation of crude oil alkanes to acetate and/or hydrogen in syntrophic partnership with methanogens in such systems. The calculated growth yield of the Marinobacter sp., assuming it grew on alkanes, was [0.0005 g(cell-C)/g(alkane-C)] suggesting that it played a minor role in alkane degradation. The dominant methanogens were hydrogenotrophs (Methanocalculus spp. from the Methanomicrobiales). Enrichment of hydrogen-oxidizing methanogens relative to acetoclastic methanogens was consistent with syntrophic acetate oxidation measured in methanogenic crude oil degrading enrichment cultures. qPCR of the Methanomicrobiales indicated growth characteristics consistent with measured rates of methane production and growth in partnership with Smithella. PMID:21914097

  5. Understanding the factors affecting the activation of alkane by Cp?Rh(CO)2 (Cp?=Cp or Cp*)

    PubMed Central

    George, Michael W.; Hall, Michael B.; Jina, Omar S.; Portius, Peter; Sun, Xue-Zhong; Towrie, Michael; Wu, Hong; Yang, Xinzheng; Zari?, Sneana D.

    2010-01-01

    Fast time-resolved infrared spectroscopic measurements have allowed precise determination of the rates of activation of alkanes by Cp?Rh(CO) (Cp?=?5-C5H5 or ?5-C5Me5). We have monitored the kinetics of C?H activation in solution at room temperature and determined how the change in rate of oxidative cleavage varies from methane to decane. The lifetime of CpRh(CO)(alkane) shows a nearly linear behavior with respect to the length of the alkane chain, whereas the related Cp*Rh(CO)(alkane) has clear oscillatory behavior upon changing the alkane. Coupled cluster and density functional theory calculations on these complexes, transition states, and intermediates provide the insight into the mechanism and barriers in order to develop a kinetic simulation of the experimental results. The observed behavior is a subtle interplay between the rates of activation and migration. Unexpectedly, the calculations predict that the most rapid process in these Cp?Rh(CO)(alkane) systems is the 1,3-migration along the alkane chain. The linear behavior in the observed lifetime of CpRh(CO)(alkane) results from a mechanism in which the next most rapid process is the activation of primary C?H bonds (?CH3 groups), while the third key step in this system is 1,2-migration with a slightly slower rate. The oscillatory behavior in the lifetime of Cp*Rh(CO)(alkane) with respect to the alkanes chain length follows from subtle interplay between more rapid migrations and less rapid primary C?H activation, with respect to CpRh(CO)(alkane), especially when the CH3 group is near a gauche turn. This interplay results in the activation being controlled by the percentage of alkane conformers. PMID:21048088

  6. IT Conversations

    NSDL National Science Digital Library

    Kaye, Doug

    For those who might see the words "IT Conversations", and think: "Oh no. A website dedicated to conversations about IT", think again. This delightful website started life in June 2003, under the careful direction of Doug Kaye and it currently contains dozens of compelling interviews, discussions, and heated debates with a number of fascinating individuals. The first-time visitor might want to begin by looking through some of the series listed on the homepage. Some of the themes addressed by these sessions include social innovation, technology development, and global security. Each interview can also be rated, so visitors may want to listen to some of the highest rated programs first, depending on their faith in such ratings. Of course, users may also wish to use the search engine offered here, as they can use this application to quickly locate different programs of interest.

  7. Two distinct monooxygenases for alkane oxidation in Nocardioides sp. strain CF8.

    PubMed

    Hamamura, N; Yeager, C M; Arp, D J

    2001-11-01

    Alkane monooxygenases in Nocardioides sp. strain CF8 were examined at the physiological and genetic levels. Strain CF8 can utilize alkanes ranging in chain length from C(2) to C(16). Butane degradation by butane-grown cells was strongly inhibited by allylthiourea, a copper-selective chelator, while hexane-, octane-, and decane-grown cells showed detectable butane degradation activity in the presence of allylthiourea. Growth on butane and hexane was strongly inhibited by 1-hexyne, while 1-hexyne did not affect growth on octane or decane. A specific 30-kDa acetylene-binding polypeptide was observed for butane-, hexane-, octane-, and decane-grown cells but was absent from cells grown with octane or decane in the presence of 1-hexyne. These results suggest the presence of two monooxygenases in strain CF8. Degenerate primers designed for PCR amplification of genes related to the binuclear-iron-containing alkane hydroxylase from Pseudomonas oleovorans were used to clone a related gene from strain CF8. Reverse transcription-PCR and Northern blot analysis showed that this gene encoding a binuclear-iron-containing alkane hydroxylase was expressed in cells grown on alkanes above C(6). These results indicate the presence of two distinct monooxygenases for alkane oxidation in Nocardioides sp. strain CF8. PMID:11679317

  8. Marine hydrocarbonoclastic bacteria as whole-cell biosensors for n-alkanes.

    PubMed

    Sevilla, Emma; Yuste, Luis; Rojo, Fernando

    2015-07-01

    Whole-cell biosensors offer potentially useful, cost-effective systems for the in-situ monitoring of seawater for hydrocarbons derived from accidental spills. The present work compares the performance of a biosensor system for the detection of alkanes in seawater, hosted in either Escherichia coli (commonly employed in whole-cell biosensors but not optimized for alkane assimilation) or different marine bacteria specialized in assimilating alkanes. The sensor system was based on the Pseudomonas putida?AlkS regulatory protein and the PalkB promoter fused to a gene encoding the green fluorescent protein. While the E. coli sensor provided the fastest response to pure alkanes (25-fold induction after 2 h under the conditions used), a sensor based on Alcanivorax borkumensis was slower, requiring 3-4?h to reach similar induction values. However, the A. borkumensis sensor showed a fourfold lower detection threshold for octane (0.5??M), and was also better at sensing the alkanes present in petrol. At petrol concentrations of 0.0125%, the A. borkumensis sensor rendered a sevenfold induction, while E. coli sensor showed no response. We discuss possible explanations to this behaviour in terms of the cellular adaptations to alkane uptake and the basal fluorescence produced by each bacterial strain, which was lowest for A. borkumensis. PMID:25874658

  9. Marine hydrocarbonoclastic bacteria as whole-cell biosensors for n-alkanes

    PubMed Central

    Sevilla, Emma; Yuste, Luis; Rojo, Fernando

    2015-01-01

    Whole-cell biosensors offer potentially useful, cost-effective systems for the in-situ monitoring of seawater for hydrocarbons derived from accidental spills. The present work compares the performance of a biosensor system for the detection of alkanes in seawater, hosted in either Escherichia coli (commonly employed in whole-cell biosensors but not optimized for alkane assimilation) or different marine bacteria specialized in assimilating alkanes. The sensor system was based on the Pseudomonas putida?AlkS regulatory protein and the PalkB promoter fused to a gene encoding the green fluorescent protein. While the E. coli sensor provided the fastest response to pure alkanes (25-fold induction after 2 h under the conditions used), a sensor based on Alcanivorax borkumensis was slower, requiring 34?h to reach similar induction values. However, the A. borkumensis sensor showed a fourfold lower detection threshold for octane (0.5??M), and was also better at sensing the alkanes present in petrol. At petrol concentrations of 0.0125%, the A. borkumensis sensor rendered a sevenfold induction, while E. coli sensor showed no response. We discuss possible explanations to this behaviour in terms of the cellular adaptations to alkane uptake and the basal fluorescence produced by each bacterial strain, which was lowest for A. borkumensis. PMID:25874658

  10. Doing Chemistry

    NSDL National Science Digital Library

    Brooks, David W.

    This website includes over 150 chemistry experiments in the following areas: Atomic Structure, Bonding, Chemical Reactions, Colligative Properties, Condensed States, Electrochemistry, Equilibrium Gases, Instrumentation, Limiting Reactant and more.

  11. Mono and bicyclic alkanes and diamondoid hydrocarbons in the Cretaceous\\/Tertiary boundary sediments at Kawaruppu, Hokkaido, Japan

    Microsoft Academic Search

    AKIRA SHIMOYAMA; HIKARU YABUTA

    Sixty-two mono- and 4 bicyclic alkanes, and 11 diamondoid hydrocarbons were detected in the Creta- ceous-Tertiary (K\\/T) boundary sediments at Kawaruppu, Hokkaido, Japan. The monocyclic alkanes in- cluded series of n-alkylcyclohexanes, methyl-n-alkylcyclohexanes and n-alkylcyclopentanes, and other alkylcyclohexanes. The bicyclic alkanes included bicyclo(3.3.1)nonane, trans-decalin, and methyldecalins. The diamondoid hydrocarbons included adamantane, and methyl- and dimethyladamantanes, and diamantane and methyldiamantanes. These mono-

  12. Occurrence of n-alkanes and polycyclic aromatic hydrocarbons in the core sediments of the Yellow Sea

    Microsoft Academic Search

    Ying Wu; Jing Zhang; Tie-zhu Mi; Bin Li

    2001-01-01

    Three core sediments (YSA10, YSB7 and YSC5) were collected from the Yellow Sea to determine the composition of n-alkanes and polycyclic aromatic hydrocarbons (PAHs) by GC. Concentrations and distributions of n-alkanes (n-C14 to n-C33) vary from 0.7 to 15.8 ?g g?1 dry weight in these core sediments. The alkane indexes (CPI and U\\/R) confirm that vascular plant inputs predominate in

  13. Molecular-isotopic stratigraphy of long-chain n-alkanes in Lake Baikal Holocene and glacial age sediments

    Microsoft Academic Search

    David Brincat; Keita Yamada; Ryoshi Ishiwatari; Hitoshi Uemura; Hiroshi Naraoka

    2000-01-01

    The molecular distribution and the carbon-isotopic composition (?13C) of n-alkanes extracted from a Lake Baikal core spanning the last 20 kyr of sediment accumulation have been investigated. A terrestrial origin has been inferred for the odd carbon-numbered long-chain (>C27) n-alkanes, on the basis of the observed high CPI27-33 values (range: 8.710.8) typical of n-alkanes derived from leaf waxes of higher

  14. Alkane hydroxylase gene (alkB) phylotype composition and diversity in northern Gulf of Mexico bacterioplankton

    PubMed Central

    Smith, Conor B.; Tolar, Bradley B.; Hollibaugh, James T.; King, Gary M.

    2013-01-01

    Natural and anthropogenic activities introduce alkanes into marine systems where they are degraded by alkane hydroxylases expressed by phylogenetically diverse bacteria. Partial sequences for alkB, one of the structural genes of alkane hydroxylase, have been used to assess the composition of alkane-degrading communities, and to determine their responses to hydrocarbon inputs. We present here the first spatially extensive analysis of alkB in bacterioplankton of the northern Gulf of Mexico (nGoM), a region that experiences numerous hydrocarbon inputs. We have analyzed 401 partial alkB gene sequences amplified from genomic extracts collected during March 2010 from 17 water column samples that included surface waters and bathypelagic depths. Previous analyses of 16S rRNA gene sequences for these and related samples have shown that nGoM bacterial community composition and structure stratify strongly with depth, with distinctly different communities above and below 100 m. Although we hypothesized that alkB gene sequences would exhibit a similar pattern, PCA analyses of operational protein units (OPU) indicated that community composition did not vary consistently with depth or other major physical-chemical variables. We observed 22 distinct OPUs, one of which was ubiquitous and accounted for 57% of all sequences. This OPU clustered with AlkB sequences from known hydrocarbon oxidizers (e.g., Alcanivorax and Marinobacter). Some OPUs could not be associated with known alkane degraders, however, and perhaps represent novel hydrocarbon-oxidizing populations or genes. These results indicate that the capacity for alkane hydrolysis occurs widely in the nGoM, but that alkane degrader diversity varies substantially among sites and responds differently than bulk communities to physical-chemical variables. PMID:24376439

  15. Proteomic Insights into Metabolic Adaptations in Alcanivorax borkumensis Induced by Alkane Utilization

    PubMed Central

    Sabirova, Julia S.; Ferrer, Manuel; Regenhardt, Daniela; Timmis, Kenneth N.; Golyshin, Peter N.

    2006-01-01

    Alcanivorax borkumensis is a ubiquitous marine petroleum oil-degrading bacterium with an unusual physiology specialized for alkane metabolism. This hydrocarbonoclastic bacterium degrades an exceptionally broad range of alkane hydrocarbons but few other substrates. The proteomic analysis presented here reveals metabolic features of the hydrocarbonoclastic lifestyle. Specifically, hexadecane-grown and pyruvate-grown cells differed in the expression of 97 cytoplasmic and membrane-associated proteins whose genes appeared to be components of 46 putative operon structures. Membrane proteins up-regulated in alkane-grown cells included three enzyme systems able to convert alkanes via terminal oxidation to fatty acids, namely, enzymes encoded by the well-known alkB1 gene cluster and two new alkane hydroxylating systems, a P450 cytochrome monooxygenase and a putative flavin-binding monooxygenase, and enzymes mediating ?-oxidation of fatty acids. Cytoplasmic proteins up-regulated in hexadecane-grown cells reflect a central metabolism based on a fatty acid diet, namely, enzymes of the glyoxylate bypass and of the gluconeogenesis pathway, able to provide key metabolic intermediates, like phosphoenolpyruvate, from fatty acids. They also include enzymes for synthesis of riboflavin and of unsaturated fatty acids and cardiolipin, which presumably reflect membrane restructuring required for membranes to adapt to perturbations induced by the massive influx of alkane oxidation enzymes. Ancillary functions up-regulated included the lipoprotein releasing system (Lol), presumably associated with biosurfactant release, and polyhydroxyalkanoate synthesis enzymes associated with carbon storage under conditions of carbon surfeit. The existence of three different alkane-oxidizing systems is consistent with the broad range of oil hydrocarbons degraded by A. borkumensis and its ecological success in oil-contaminated marine habitats. PMID:16707669

  16. The formation of bicyclo[n.2.0]alkan-1-ols from the reaction of the lithium enolates of simple ketones and phenyl vinyl sulfoxide.

    PubMed

    Loughlin, Wendy A; McCleary, Michelle A

    2003-04-21

    The enolates generated from cyclopentanone, cycloheptanone or cyclooctanone and LDA at -78 degrees C in THF react with (+/-)-phenyl vinyl sulfoxide under controlled conditions of temperature, reaction time, and concentration. Upon oxidation with MCPBA of the product mixtures, the novel sulfonylbicyclo[3.2.0]heptan-1-ols10-12,sulfonylbicyclo[5.2.0]-nonan-1-ols 16-18, and sulfonylbicyclo[6.2.0]decan-1-ols 21 and 22 in conjunction with alkylated ketones 8, 9, 15, 19 and 20 were obtained from the respective ketones. The enolate generated from cyclobutanone and LDA at -78 degrees C in THF reacts with (+/-)-phenyl vinyl sulfoxide and upon oxidation with MCPBA, the cyclohexanone 4 and monoalkylated cyclobutanone 5 were obtained. The ratio of bicyclo[n.2.0]alkan-1-ol to alkylated products varied with the ketone enolate, conversion of phenyl vinyl sulfoxide, time, temperature and concentration of reaction and the stability and steric strain of the final bicyclo[n.2.0]alkan-1-ol product. PMID:12929665

  17. Chem 681 Quantum Chemistry Chemistry 681

    E-print Network

    Chem 681 Quantum Chemistry Chemistry 681 Introduction to Quantum Chemistry Fall 2003 Course outline-consistent field (Hartree-Fock) theory. G.S. Ezra 1 Cornell University #12;Chem 681 Quantum Chemistry 8. Molecules

  18. Interview Transcript A Conversation with Andrew Benson

    E-print Network

    to the discovery of the Calvin-Benson cycle in photosynthesis, a pathway essential to the growth of all plants's specialty? #12;3 [02:09] BENSON: He was a specialist in carbohydrate chemistry, anything involving sugar to the absorption and conversion of carbon dioxide to carbohydrates. [04:17] BUCHANAN: In photosynthesis. BENSON

  19. Fundamental studies on CH activation for alkane fuel cell applications

    Microsoft Academic Search

    Harry B. Gray; Fred C. Anson; Jack L. Beauchamp; John E. Bercaw; Jay A. Labinger

    1995-01-01

    The objective of this project was to develop new chemistry that could be applied to an efficient fuel cell operating directly on organic fuels under ambient or near-ambient conditions. The report summarizes scientific accomplishments, including the discoveries that (1) soluble metal complexes offer potential advantages over traditional metal surfaces for hydrocarbon oxidation, although simultaneously optimizing the rate and potential for

  20. n-Alkane distributions as indicators of novel ecosystem development in western boreal forest soils

    NASA Astrophysics Data System (ADS)

    Norris, Charlotte; Dungait, Jennifer; Quideau, Sylvie

    2013-04-01

    Novel ecosystem development is occurring within the western boreal forest of Canada due to land reclamation following surface mining in the Athabasca Oil Sands Region. Sphagnum peat is the primary organic matter amendment used to reconstruct soils in the novel ecosystems. We hypothesised that ecosystem recovery would be indicated by an increasing similarity in the biomolecular characteristics of novel reconstructed soil organic matter (SOM) derived from peat to those of natural boreal ecosystems. In this study, we evaluated the use of the homologous series of very long chain (>C20) n-alkanes with odd-over-even predominance as biomarker signatures to monitor the re-establishment of boreal forests on reconstructed soils. The lipids were extracted from dominant vegetation inputs and SOM from a series of natural and novel ecosystem reference plots. We observed unique very long n-alkane signatures of the source vegetation, e.g. Sphagnum sp. was dominated by C31 and aspen (Populus tremuloides Michx.) leaves by C25. Greater concentrations of very long chain n-alkanes were extracted from natural than novel ecosystem SOM (p<0.01), and their distribution differed between the two systems (p<0.001) and reflected the dominant vegetation input. Our results indicate that further research is required to clarify the influence of vegetation or disturbance on the signature of very long chain n-alkanes in SOM; however, the use of n-alkanes as biomarkers of ecosystem development is a promising method.

  1. Whole?cell bacterial bioreporter for actively searching and sensing of alkanes and oil spills

    PubMed Central

    Zhang, Dayi; He, Yi; Wang, Yun; Wang, Hui; Wu, Lin; Aries, Eric; Huang, Wei E.

    2012-01-01

    Summary Acinetobacter baylyi ADP1 was found to tolerate seawater and have a special ability of adhering to an oilwater interface of 1080?m emulsified mineral and crude oil droplets. These properties make ADP1 an ideal bacterial chassis for constructing bioreporters that are able to actively search and sense oil spill in water and soils. Acinetobacter baylyi bioreporter ADPWH_alk was developed and applied to the detection of alkanes and alkenes in water, seawater and soils. Bioreporter ADPWH_alk was able to detect a broad range of alkanes and alkenes with carbon chain length from C7 to C36. So far, ADPWH_alk is the only bioreporter that is able to detect alkane with carbon chain length greater than C18. This bioreporter responded to the alkanes in about 30?min and it was independent to the cell growth phase because of two point mutations in alkM promoter recognized by alkane regulatory protein ALKR. ADPWH_alk was applied to detect mineral oil, Brent, Chestnut and Sirri crude oils in water and seawater in the range 0.1100?mg?l?1, showing that the bioreporter oil detection was semi?quantitative. This study demonstrates that ADPWH_alk is a rapid, sensitive and semi?quantitative bioreporter that can be useful for environmental monitoring and assessment of oil spills in seawater and soils. PMID:21951420

  2. Oxygenates from light alkanes catalyzed by NO{sub x} in the gas phase

    SciTech Connect

    Otsuka, Kiyoshi; Takahashi, Ryo; Yamanaka, Ichiro [Tokyo Inst. of Tech., (Japan). Dept. of Chemical Engineering] [Tokyo Inst. of Tech., (Japan). Dept. of Chemical Engineering

    1999-07-01

    The partial oxidations of light alkanes (methane, ethane, propane, and iso-butane) catalyzed by NO{sub x} in the gas phase have been studied at a pressure of less than 1 bar. For all the alkanes tested, the addition of NO to the mixture of alkanes and O{sub 2} enhanced the selectivities and the yields of oxygenates remarkably. It was suggested that NO{sub 2} generated from NO and O{sub 2} initiated the oxidation of alkanes and would specifically accelerate the C-C bond fission, enhancing the formation of C{sub 1}-oxygenates from ethane, propane, and iso-butane. No{sub 2} and NO would be used as a homogeneous catalyst at >600 C because nitroalkanes formed were decomposed completely, releasing the NO{sub x}. The comparison of the product distributions for the decomposition and oxidation of nitroalkanes and alkylnitrites strongly suggested that the oxygenates (HCHO, CH{sub 3}CHO, and CH{sub 3}COCH{sub 3}) were formed from the corresponding alkylnitrites which must be the reaction intermediates during the oxidation of alkanes with an O{sub 2} and NO mixture.

  3. Whole-cell bacterial bioreporter for actively searching and sensing of alkanes and oil spills.

    PubMed

    Zhang, Dayi; He, Yi; Wang, Yun; Wang, Hui; Wu, Lin; Aries, Eric; Huang, Wei E

    2012-01-01

    Acinetobacter baylyi ADP1 was found to tolerate seawater and have a special ability of adhering to an oil-water interface of 10-80 m emulsified mineral and crude oil droplets. These properties make ADP1 an ideal bacterial chassis for constructing bioreporters that are able to actively search and sense oil spill in water and soils. Acinetobacter baylyi bioreporter ADPWH_alk was developed and applied to the detection of alkanes and alkenes in water, seawater and soils. Bioreporter ADPWH_alk was able to detect a broad range of alkanes and alkenes with carbon chain length from C7 to C36. So far, ADPWH_alk is the only bioreporter that is able to detect alkane with carbon chain length greater than C18. This bioreporter responded to the alkanes in about 30 min and it was independent to the cell growth phase because of two point mutations in alkM promoter recognized by alkane regulatory protein ALKR. ADPWH_alk was applied to detect mineral oil, Brent, Chestnut and Sirri crude oils in water and seawater in the range 0.1-100 mg l(-1), showing that the bioreporter oil detection was semi-quantitative. This study demonstrates that ADPWH_alk is a rapid, sensitive and semi-quantitative bioreporter that can be useful for environmental monitoring and assessment of oil spills in seawater and soils. PMID:21951420

  4. Biogeographic variation of foliar n-alkanes of Juniperus communis var. saxatilis Pallas from the Balkans.

    PubMed

    Raj?evi?, Nemanja; Jana?kovi?, Pedja; Dodo, Tanja; Teevi?, Vele; Marin, Petar D

    2014-12-01

    The composition of the epicuticular n-alkanes isolated from the leaves of ten populations of Juniperus communis L. var. saxatilis Pallas from central (continental) and western (coastal) areas of the Balkan Peninsula was characterized by GC-FID and GC/MS analyses. In the leaf waxes, 14 n-alkane homologues with chain-lengths ranging from C22 to C35 were identified. All samples were dominated by n-tritriacontane (C33 ), but differences in two other dominant n-alkanes allowed separating the coastal from the continental populations. Several statistical methods (ANOVA, principal component, discriminant, and cluster analyses as well as the Mantel test) were deployed to analyze the diversity and variability of the epicuticular-leaf-n-alkane patterns of the ten natural populations of J. communis var. saxatilis and their relation to different geographic and bioclimatic parameters. Cluster analysis showed a high correlation of the leaf-n-alkane patterns with the geographical distribution of the investigated samples, differentiating the coastal from the continental populations of this taxon. Several bioclimatic parameters related to aridity were highly correlated with this differentiation. PMID:25491336

  5. Circumstellar chemistry

    NASA Technical Reports Server (NTRS)

    Glassgold, Alfred E.; Huggins, Patrick J.

    1987-01-01

    The study of the outer envelopes of cool evolved stars has become an active area of research. The physical properties of CS envelopes are presented. Observations of many wavelengths bands are relevant. A summary of observations and a discussion of theoretical considerations concerning the chemistry are summarized. Recent theoretical considerations show that the thermal equilibrium model is of limited use for understanding the chemistry of the outer CS envelopes. The theoretical modeling of the chemistry of CS envelopes provides a quantitive test of chemical concepts which have a broader interest than the envelopes themselves.

  6. Energy Conversion and Storage Program: 1992 Annual report

    Microsoft Academic Search

    Cairns

    1993-01-01

    This report is the 1992 annual progress report for the Energy Conversion and Storage Program, a part of the Energy and Environment Division of the Lawrence Berkeley Laboratory. Work described falls into three broad areas: electrochemistry; chemical applications; and materials applications. The Energy Conversion and Storage Program applies principles of chemistry and materials science to solve problems in several areas:

  7. Cooperative Chemistry

    NSDL National Science Digital Library

    Allan A. Gahr

    2003-02-01

    Concept mapping in the organic chemistry laboratory can supplant cookbook activities with higher cognitive exercises. The common thread of most organic lab experiments is the synthesis, isolation, purification, and characterization of a carbon compound. T

  8. Radioanalytical Chemistry

    NSDL National Science Digital Library

    Hardy, James K.

    This website provides a course on the use of radionuclides in analytical chemistry. Types of radioactive decay are discussed as well as the techniques of scintillation counting, neutron activation analysis, and gamma spectroscopy.

  9. Precolumbian Chemistry.

    ERIC Educational Resources Information Center

    Robinson, Janet Bond

    1995-01-01

    Describes the content and development of a curriculum that provides an approach to descriptive chemistry and the history of technology through consideration of the pottery, metallurgy, pigments, dyes, agriculture, and medicine of pre-Columbian people. (DDR)

  10. Green Chemistry

    NSDL National Science Digital Library

    2011-03-02

    Learn about a study in which participants discovered contaminants in their homes, and how green chemistry may provide alternatives to such everyday toxins, in this video adapted from Contaminated Without Consent.

  11. Chemistry Notes.

    ERIC Educational Resources Information Center

    School Science Review, 1981

    1981-01-01

    Describes 13 activities, experiments and demonstrations, including the preparation of iron (III) chloride, simple alpha-helix model, investigating camping gas, redox reactions of some organic compounds, a liquid crystal thermometer, and the oxidation number concept in organic chemistry. (JN)

  12. Surveys of research in the Chemistry Division, Argonne National Laboratory

    SciTech Connect

    Grazis, B.M. (ed.)

    1992-01-01

    Research reports are presented on reactive intermediates in condensed phase (radiation chemistry, photochemistry), electron transfer and energy conversion, photosynthesis and solar energy conversion, metal cluster chemistry, chemical dynamics in gas phase, photoionization-photoelectrons, characterization and reactivity of coal and coal macerals, premium coal sample program, chemical separations, heavy elements coordination chemistry, heavy elements photophysics/photochemistry, f-electron interactions, radiation chemistry of high-level wastes (gas generation in waste tanks), ultrafast molecular electronic devices, and nuclear medicine. Separate abstracts have been prepared. Accelerator activites and computer system/network services are also reported.

  13. Surveys of research in the Chemistry Division, Argonne National Laboratory

    SciTech Connect

    Grazis, B.M. [ed.

    1992-11-01

    Research reports are presented on reactive intermediates in condensed phase (radiation chemistry, photochemistry), electron transfer and energy conversion, photosynthesis and solar energy conversion, metal cluster chemistry, chemical dynamics in gas phase, photoionization-photoelectrons, characterization and reactivity of coal and coal macerals, premium coal sample program, chemical separations, heavy elements coordination chemistry, heavy elements photophysics/photochemistry, f-electron interactions, radiation chemistry of high-level wastes (gas generation in waste tanks), ultrafast molecular electronic devices, and nuclear medicine. Separate abstracts have been prepared. Accelerator activites and computer system/network services are also reported.

  14. Stratospheric chemistry

    SciTech Connect

    Brune, W.H. (USAF, Geophysics Laboratory, Hanscom AFB, MA (United States))

    1991-01-01

    Advances in stratospheric chemistry made by investigators in the United States from 1987 to 1990 are reviewed. Subject areas under consideration include photochemistry of the polar stratosphere, photochemistry of the global stratosphere, and assessments of inadvertent modification of the stratosphere by anthropogenic activity. Particular attention is given to early observations and theories, gas phase chemistry, Antarctic observations, Arctic observations, odd-oxygen, odd-hydrogen, odd-nitrogen, halogens, aerosols, modeling of stratospheric ozone, and reactive nitrogen effects.

  15. n-Alkanes in surficial sediments of Visakhapatnam harbour, east coast of India

    NASA Astrophysics Data System (ADS)

    Punyu, V. R.; Harji, R. R.; Bhosle, N. B.; Sawant, S. S.; Venkat, K.

    2013-04-01

    Surface sediments collected from 19 stations along Visakhapatnam harbour were analysed for organic carbon (OC), ? 13Coc, total lipids (TL), total hydrocarbon (THC), n-alkane concentration and composition. OC, ? 13Coc, TL and THC ranged from 0.6% to 7.6%, -29.3 to -23.8, 300 to 14,948 \\upmu g g - 1 dw, and 0.2 to 2,277 \\upmu g g - 1 dw, respectively. Predominance of even carbon numbers n-alkanes C12-C21 with carbon preference index (CPI) of <1 suggests major microbial influence. Fair abundance of odd carbon number n-alkanes in the range of C15-C22 and C23-C33 indicates some input from phytoplankton and terrestrial sources, respectively. Petrogenic input was evident from the presence of hopanes and steranes. The data suggest that organic matter (OM) sources varied spatially and were mostly derived from mixed source.

  16. Preparation and characterization of n-alkane/water emulsion stabilized by cyclodextrin.

    PubMed

    Inoue, Motoki; Hashizaki, Kaname; Taguchi, Hiroyuki; Saito, Yoshihiro

    2009-01-01

    Emulsions consisting of n-alkane/water using alpha, beta, and gamma-cyclodextrin (alpha, beta, and gamma-CD) as an emulsifier were prepared and characterized by means of several physicochemical techniques. A phase diagram of the n-alkane/CD/water system showed that an oil in water (O/W) emulsion can be prepared from a mixture of the appropriate composition. The dissolved n-alkane/CD complexes formed at low CD concentrations showed surface-activity, but emulsions could not be prepared from these complexes. On the other hand, the precipitated complexes formed at high CD concentrations when adsorbed to the oil/water interface, and served as an emulsifier for formation of emulsions. These results showed that the emulsions formed were of the Pickering emulsion. In addition emulsion formation was governed by the wettability and the surface free energy of the precipitated complexes. PMID:19145062

  17. Monitoring alkane degradation by single BioBrick integration to an optimal cellular framework.

    PubMed

    Santala, Suvi; Karp, Matti; Santala, Ville

    2012-02-17

    Synthetic biology enables rewiring and reconstruction of desirable biochemical routes using well-characterized BioBricks. One goal is to optimize these biological systems in terms of robustness, functionality, and simplicity. Thus, in addition to optimizing the molecular level of the metabolic network, choosing an optimal "chassis" can have a great significance in the constructed system. As an example, this study presents a simplified system for monitoring and studying long-chain n-alkane degradation in Acinetobacter baylyi ADP1 online, provided by a single BioBrick insertion, bacterial luciferase luxAB. The system exploits the natural alkane degradation machinery of ADP1 and a sensitive response of bacterial luciferase to a specific intermediate, providing important aspects to natural alkane degradation kinetics. The study suggests the monitoring system to be applicable in the field of environmental biotechnology and emphasizes the utility of ADP1 as a host in both model systems and applications. PMID:23651046

  18. Distribution, activity and function of short-chain alkane degrading phylotypes in hydrothermal vent sediments

    NASA Astrophysics Data System (ADS)

    Adams, M. M.; Joye, S. B.; Hoarfrost, A.; Girguis, P. R.

    2012-12-01

    Global geochemical analyses suggest that C2-C4 short chain alkanes are a common component of the utilizable carbon pool in deep-sea sediments worldwide and have been found in diverse ecosystems. From a thermodynamic standpoint, the anaerobic microbial oxidation of these aliphatic hydrocarbons is more energetically yielding than the anaerobic oxidation of methane (AOM). Therefore, the preferential degradation of these hydrocarbons may compete with AOM for the use of oxidants such as sulfate, or other potential oxidants. Such processes could influence the fate of methane in the deep-sea. Sulfate-reducing bacteria (SRB) from hydrocarbon seep sediments of the Gulf of Mexico and Guaymas Basin have previously been enriched that anaerobically oxidize short chain alkanes to generate CO2 with the preferential utilization of 12C-enriched alkanes (Kniemeyer et al. 2007). Different temperature regimens along with multiple substrates were tested and a pure culture (deemed BuS5) was isolated from mesophilic enrichments with propane or n-butane as the sole carbon source. Through comparative sequence analysis, strain BuS5 was determined to cluster with the metabolically diverse Desulfosarcina / Desulfococcus cluster, which also contains the SRB found in consortia with anaerobic, methane-oxidizing archaea in seep sediments. Enrichments from a terrestrial, low temperature sulfidic hydrocarbon seep also corroborated that propane degradation occurred with most bacterial phylotypes surveyed belonging to the Deltaproteobacteria, particularly Desulfobacteraceae (Savage et al. 2011). To date, no microbes capable of ethane oxidation or anaerobic C2-C4 alkane oxidation at thermophilic temperature have been isolated. The sediment-covered, hydrothermal vent systems found at Middle Valley (Juan de Fuca Ridge, eastern Pacific Ocean) are a prime environment for investigating mesophilic to thermophilic anaerobic oxidation of short-chain alkanes, given the elevated temperatures and dissolved hydrocarbon species characteristic of these metalliferous sediments. These systems are also characterized by sharp physicochemical gradients that have been shown to have a pronounced effect on microbial ecology and activity. Sediments were collected from a Middle Valley field with relatively high concentrations of short-chain alkanes and incubated in anaerobic batch reactors with each individual alkane (C1, C2, C3 and C4, respectively) at a range of temperatures (25, 55 and 75 C) to mimic environmental physico-chemical conditions in a closed system. Stable carbon isotope ratios and radiotracer incubations provide clear evidence for C2-C4 alkane oxidation in the sediments over time. Upon identifying sediments with anaerobic alkane oxidation activity, microbial communities were screened via 16S rRNA pyrosequencing, and key phylotypes were then quantified using both molecular and microscopic methods. There were shifts in overall community composition and putative alkane-oxidizing phylotypes after the incubation period with the alkane substrates. These are the first evidence to date indicating that anaerobic C2-C4 alkane oxidation occurs across a broad range of temperatures in metalliferous sediments.

  19. Modeling SOA formation from alkanes and alkenes in chamber experiments: effect of gas/wall partitioning of organic vapors.

    NASA Astrophysics Data System (ADS)

    Stphanie La, Yuyi; Camredon, Marie; Ziemann, Paul; Ouzebidour, Farida; Valorso, Richard; Madronich, Sasha; Lee-Taylor, Julia; Hodzic, Alma; Aumont, Bernard

    2014-05-01

    Oxidation products of Intermediate Volatility Organic Compounds (IVOC) are expected to be the major precursors of secondary organic aerosols (SOA). Laboratory experiments were conducted this last decade in the Riverside APRC chamber to study IVOC oxidative mechanisms and SOA formation processes for a large set of linear, branched and cyclic aliphatic hydrocarbons (Ziemann, 2011). This dataset are used here to assess the explicit oxidation model GECKO-A (Generator for Explicit Chemistry and Kinetics of Organics in the Atmosphere) (Aumont et al., 2005). The simulated SOA yields agree with the general trends observed in the chamber experiments. They are (i) increasing with the increasing carbon number; (ii) decreasing with increasing methyl branch number; and (iii) increasing for cyclic compounds compared to their corresponding linear analogues. However, simulated SOA yields are systematically overestimated regardless of the precursors, suggesting missing processes in the model. In this study, we assess whether gas-to-wall partitioning of organic vapors can explain these model/observation mismatches (Matsunaga and Ziemann, 2010). First results show that GECKO-A outputs better match the observations when wall uptake of organic vapors is taken into account. Effects of gas/wall partitioning on SOA yields and composition will be presented. Preliminary results suggest that wall uptake is a major process influencing SOA production in the Teflon chambers. References Aumont, B., Szopa, S., Madronich, S.: Modelling the evolution of organic carbon during its gas-phase tropospheric oxidation: development of an explicit model based on a self generating approach. Atmos.Chem.Phys., 5, 2497-2517 (2005). P. J. Ziemann: Effects of molecular structure on the chemistry of aerosol formation from the OH-radical-initiated oxidation of alkanes and alkenes, Int. Rev.Phys.Chem., 30:2, 161-195 (2011). Matsunaga, A., Ziemann, P. J.: Gas-wall partitioning of organic compounds in a Teflon film chamber and potential effects on reaction product and aerosol yield measurements, Aerosol Sci. Technol., 44:10, 881-892 (2010).

  20. Cyanobacterial alkane biosynthesis further expands the catalytic repertoire of the ferritin-like di-iron-carboxylate proteins

    PubMed Central

    Krebs, Carsten; Bollinger, J. Martin; Booker, Squire J.

    2011-01-01

    Summary Enzymes that activate dioxygen at carboxylate-bridged non-heme diiron clusters residing within ferritin-like, four-helix-bundle protein architectures have crucial roles in, among other processes, the global carbon cycle (e.g., soluble methane monooxygenase), fatty acid biosynthesis [plant fatty acyl-acyl carrier protein (ACP) desaturases], DNA biosynthesis [the R2 or ?2 subunits of class Ia ribonucleotide reductases (RNRs)], and cellular iron trafficking (ferritins). Classic studies on class Ia RNRs showed long ago how this obligatorily oxidative di-iron/O2 chemistry can be used to activate an enzyme for even a reduction reaction, and more recent investigations of class Ib and Ic RNRs, coupled with earlier studies on dimanganese catalases, have shown that members of this protein family can also incorporate either one or two Mn ions and use them in place of iron for redox catalysis. These two strategies oxidative activation for non-oxidative reactions and use of alternative metal ions expand the catalytic repertoire of the family, probably to include activities that remain to be discovered. Indeed, a recent study has suggested that fatty aldehyde decarbonylases (ADs) from cyanobacteria, purported to catalyze a redox-neutral cleavage of a Cn aldehyde to the Cn?1 alkane (or alkene) and CO, also belong to this enzyme family and are most similar in structure to two other members with heterodinuclear (Mn-Fe) cofactors. Here, we first briefly review both the chemical principles underlying the O2-dependent oxidative chemistry of the classical di-iron-carboxylate proteins and the two aforementioned strategies that have expanded their functional range, and then consider what metal ion(s) and what chemical mechanism(s) might be employed by the newly discovered cyanobacterial ADs. PMID:21440485

  1. Transition temperatures and contact angles in the sequential-wetting scenario of n-alkanes on (salt) water

    Microsoft Academic Search

    Volker C. Weiss; Joseph O. Indekeu

    2003-01-01

    Alkanes of medium chain length show an unusual wetting behavior on (salt) water, exhibiting a sequence of two changes in the wetting state. When deposited on the water surface at low temperatures, the liquid alkane forms discrete droplets that are interconnected only by a molecularly thin film. On increase of the temperature, there occurs a sudden jump of the film

  2. Transition temperatures and contact angles in the sequential-wetting scenario of n-alkanes on (salt) water

    Microsoft Academic Search

    Volker C. Weiss; Joseph O. Indekeu

    2004-01-01

    Alkanes of medium chain length show an unusual wetting behavior on (salt) water, exhibiting a sequence of two changes in the wetting state. When deposited on the water surface at low temperatures, the liquid alkane forms discrete droplets that are interconnected only by a molecularly thin film. On increase of the temperature, there occurs a sudden jump of the film

  3. Phase equilibria calculations with a modified SAFT equation of state. 2: Binary mixtures of n-alkanes, 1-alkanols, and water

    Microsoft Academic Search

    Thomas Kraska; Keith E. Gubbins

    1996-01-01

    The Lennard-Jones-statistical association fluid theory (LJ-SAFT) is applied to binary mixtures containing one self-associating and one nonassociating substance. The binary systems studied here are n-alkane\\/n-alkane, 1-alkanol\\/n-alkane, and water\\/n-alkane mixtures. For cases where the dipole-dipole term is needed, the influence of induction is also investigated. The results with LJ-SAFT exhibit better agreement with experimental data than SAFT. This improvement is due

  4. Regioselective alkane hydroxylation with a mutant CYP153A6 enzyme

    DOEpatents

    Koch, Daniel J.; Arnold, Frances H.

    2013-01-29

    Cytochrome P450 CYP153A6 from Myobacterium sp. strain HXN1500 was engineered using in-vivo directed evolution to hydroxylate small-chain alkanes regioselectively. Mutant CYP153A6-BMO1 selectively hydroxylates butane and pentane at the terminal carbon to form 1-butanol and 1-pentanol, respectively, at rates greater than wild-type CYP153A6 enzymes. This biocatalyst is highly active for small-chain alkane substrates and the regioselectivity is retained in whole-cell biotransformations.

  5. Determination of the molecular area on a liquid surface from thermodynamic functions: Application to alkanes

    SciTech Connect

    Carre, A.; Vial, J. (Corning Europe, Inc., Avon (France))

    1993-10-15

    A method is proposed to calculate the molecular area on the surface of a liquid from thermodynamic parameters such as the molar internal energy, the surface free energy, and the surface entropy. When the method is applied to the series of normal alkanes, it allows calculation of the area of the molecules on these liquid surfaces and to deduce the orientation of these molecules. Moreover, the molecular areas of the first terms of the alkane series and of hydrogen are also obtained by extrapolation.

  6. Determination of n-alkane content in middle and heavy distillates by gas chromatography

    SciTech Connect

    Fadeev, V.S.; Shteingardt, N.S.

    1987-07-01

    The authors have modified a procedure of determination of n-alkane content in middle and heavy distillates by gas chromatography. The zeolite is replaced by a surface-layer absorbent consisting of grains of diatomite on which there has been deposited a surface layer of MgA zeolite particles, and the helium is replaced by hydrogen. A special chromatograph attachment is described and the chromatograms are calculated on the basis of the heights or areas of the peaks of the charge and the impurity hydrocarbons which are not n-alkanes.

  7. Direct dissociative chemisorption of alkanes on Pt(111): Influence of molecular complexity

    SciTech Connect

    Weaver, Jason F. [Department of Chemical Engineering, Stanford University, Stanford, California 94305 (United States)] [Department of Chemical Engineering, Stanford University, Stanford, California 94305 (United States); Krzyzowski, Michael A. [Department of Chemical Engineering, Stanford University, Stanford, California 94305 (United States)] [Department of Chemical Engineering, Stanford University, Stanford, California 94305 (United States); Madix, Robert J. [Department of Chemical Engineering, Stanford University, Stanford, California 94305 (United States)] [Department of Chemical Engineering, Stanford University, Stanford, California 94305 (United States)

    2000-01-01

    The direct dissociative chemisorption of ethane, propane, n-butane, isobutane, and neopentane on Pt(111) was investigated as a function of the initial translational energy, E{sub T}, polar angle of incidence, {theta}{sub i}, initial vibrational temperature, and surface temperature using supersonic molecular beam techniques. For each alkane, the initial probability for direct dissociative chemisorption scales with the initial normal energy of the alkanes, E{sub n}=E{sub T} cos{sup 2} {theta}{sub i}, and is independent of both the surface temperature and initial vibrational energy of the alkanes under the experimental conditions employed. Above initial normal energies of approximately 125 kJ/mol, at constant E{sub n}, the dissociation probability decreases with increasing chain length of the C{sub 2}-C{sub 4} linear alkanes; however, the dissociation probability of neopentane is greater than that of isobutane, and both isobutane and neopentane are more reactive than n-butane. By assuming that cleavage of primary C-H bonds is the dominant reaction pathway for all of the alkanes investigated here, the trends in reactivity are best explained by considering the differences in the steric factors for primary C-H bond cleavage for these alkanes. Secondary C-H bond cleavage does appear to contribute to the reactivity of propane and n-butane but only at the highest energies examined. Additionally, the reaction probabilities of each of these alkanes were estimated using a statistical model recently proposed by Ukrainstev and Harrison [J. Chem. Phys. 101, 1564 (1994)]. Assuming cleavage of only primary C-H bonds, the trends in reactivity for ethane, propane, n-butane, and isobutane were qualitatively reproduced by the statistical model; however, except for ethane, which was used to obtain the necessary parameters for the theory, there was poor quantitative agreement, and the predictions for neopentane were significantly lower than the measured values. The model also predicts that the dissociation probability is enhanced by increasing the energy in all vibrational modes, which is inconsistent with the experimental results. Thus, we believe that direct alkane dissociation would be better described using a dynamical rather than statistical approach. (c) 2000 American Institute of Physics.

  8. Thermal non-oxidative aromatization of light alkanes catalyzed by gallium nitride.

    PubMed

    Li, Lu; Mu, Xiaoyue; Liu, Wenbo; Kong, Xianghua; Fan, Shizhao; Mi, Zetian; Li, Chao-Jun

    2014-12-15

    The thermal catalytic activity of GaN in non-oxidative alkane dehydroaromatization has been discovered for the first time. The origin of the catalytic activity was studied experimentally and theoretically. Commercially available GaN powders with a wurtzite crystal structure showed superior stability and reactivity for converting light alkanes, including methane, propane, n-butane, n-hexane and cyclohexane into benzene at an elevated temperature with high selectivity. The catalyst is highly robust and can be used repeatedly without noticeable deactivation. PMID:25336448

  9. Mass effect on the Soret coefficient in n-alkane mixtures

    SciTech Connect

    Alonso de Mezquia, David; Mounir Bou-Ali, M., E-mail: mbouali@mondragon.edu [Mechanical and Manufacturing Department, Engineering Faculty of Mondragon Unibertsitatea, Loramendi 4 Apdo. 23, 20500 Mondragon (Spain); Madariaga, J. Antonio; Santamara, Carlos [Department of Applied Physics II, University of Basque Country (UPV/EHU), Apdo. 644, 48080 Bilbao (Spain)] [Department of Applied Physics II, University of Basque Country (UPV/EHU), Apdo. 644, 48080 Bilbao (Spain)

    2014-02-28

    We have determined the Soret coefficient of different equimolar and non equimolar n-alkane mixtures from measurements of the molecular diffusion and thermal diffusion coefficients. It is shown that equimolar mixtures behave as isotopic-like mixtures in which only the mass effect contributes to the Soret effect. In non equimolar mixtures, a small linear dependence with the molar fraction is observed. Finally, we have obtained a new correlation, which allows the determination of the Soret coefficient of n-alkane mixtures using the data of viscosity, the thermal expansion coefficient of the pure components, and the density of the equimolar mixture.

  10. Toxics release inventory: List of toxic chemicals within the polychlorinated alkanes category and guidance for reporting

    SciTech Connect

    NONE

    1995-02-01

    Section 313 of the Emergency Planning and Community Right-to-Know Act of 1986 (EPCRA) requires certain facilities manufacturing, processing, or otherwise using listed toxic chemicals to report their environmental releases of such chemicals annually. On November 30, 1994 EPA added 286 chemicals and chemical categories. Six chemical categories (nicotine and salts, strychnine and salts, polycyclic aromatic compounds, water dissociable nitrate compounds, diisocyanates, and polychlorinated alkanes) are included in these additions. At the time of the addition, EPA indicated that the Agency would develop, as appropriate, interpretations and guidance that the Agency determines are necessary to facilitate accurate reporting for these categories. This document constitutes such guidance for the polychlorinated alkanes category.

  11. Distribution and Variability of n-Alkanes in Epicuticular Waxes of Sedum Species from the Central Balkan Peninsula: Chemotaxonomic Importance.

    PubMed

    Jovanovi?, Sneana ?; Zlatkovi?, Bojan K; Stojanovi?, Gordana S

    2015-05-01

    For the first time, the n-alkane distribution and variability of the epicuticular waxes within 22 Sedum taxa was reported with focus on the chemotaxonomy of native Sedum representatives from the central Balkan Peninsula, compared to their relations with four other species of the Crassulaceae family. By GC/MS and GC-FID identification and quantification, it was established that n-alkanes C27 , C29 , C31 , C33 , and C35 were the dominant constituents of the examined epicuticular wax samples. Applying multivariate statistical analyses including agglomerative hierarchical clustering (AHC) and principal component analysis (PCA), the relation according to the n-alkane composition between the examined samples was established. It was shown that the n-alkane variability of the central Balkan Sedum species was considerable and that n-alkanes might not be very reliable taxonomic markers for these species. PMID:26010665

  12. Detailed chemical kinetic models for large n-alkanes and iso-alkanes found in conventional and F-T diesel fuels

    SciTech Connect

    Westbrook, C K; Pitz, W J; Mehl, M; Curran, H J

    2009-03-09

    n-Hexadecane and 2,2,4,4,6,8,8-heptamethylnonane represent the primary reference fuels for diesel that are used to determine cetane number, a measure of the ignition property of diesel fuel. With the development of chemical kinetics models for both primary reference fuels, a new capability is now available to model diesel fuel ignition. Additionally, we have developed chemical kinetic models for a whole series of large n-alkanes and a large iso-alkane to represent these chemical classes in fuel surrogates for conventional and future fuels. These chemical kinetic models are used to predict the effect of the aforementioned fuel components on ignition characteristics under conditions found in internal combustion engines.

  13. Ab initio simulations reveal that reaction dynamics strongly affect product selectivity for the cracking of alkanes over H-MFI.

    PubMed

    Zimmerman, Paul M; Tranca, Diana C; Gomes, Joseph; Lambrecht, Daniel S; Head-Gordon, Martin; Bell, Alexis T

    2012-11-28

    Product selectivity of alkane cracking catalysis in the H-MFI zeolite is investigated using both static and dynamic first-principles quantum mechanics/molecular mechanics simulations. These simulations account for the electrostatic- and shape-selective interactions in the zeolite and provide enthalpic barriers that are closely comparable to experiment. Cracking transition states for n-pentane lead to a metastable intermediate (a local minimum with relatively small barriers to escape to deeper minima) where the proton is shared between two hydrocarbon fragments. The zeolite strongly stabilizes these carbocations compared to the gas phase, and the conversion of this intermediate to more stable species determines the product selectivity. Static reaction pathways on the potential energy surface starting from the metastable intermediate include a variety of possible conversions into more stable products. One-picosecond quasiclassical trajectory simulations performed at 773 K indicate that dynamic paths are substantially more diverse than the potential energy paths. Vibrational motion that is dynamically sampled after the cracking transition state causes spilling of the metastable intermediate into a variety of different products. A nearly 10-fold change in the branching ratio between C2/C3 cracking channels is found upon inclusion of post-transition-state dynamics, relative to static electronic structure calculations. Agreement with experiment is improved by the same factor. Because dynamical effects occur soon after passing through the rate-limiting transition state, it is the dynamics, and not only the potential energy barriers, that determine the catalytic selectivity. This study suggests that selectivity in zeolite catalysis is determined by high temperature pathways that differ significantly from 0 K potential surfaces. PMID:23072346

  14. Enhanced Translocation and Growth of Rhodococcus erythropolis PR4 in the Alkane Phase of Aqueous-Alkane Two Phase Cultures Were Mediated by GroEL2 Overexpression

    PubMed Central

    Takihara, Hayato; Ogihara, Jun; Yoshida, Takao; Okuda, Shujiro; Nakajima, Mutsuyasu; Iwabuchi, Noriyuki; Sunairi, Michio

    2014-01-01

    We previously reported that R. erythropolis PR4 translocated from the aqueous to the alkane phase, and then grew in two phase cultures to which long-chain alkanes had been added. This was considered to be beneficial for bioremediation. In the present study, we investigated the proteins involved in the translocation of R. erythropolis PR4. The results of our proteogenomic analysis suggested that GroEL2 was upregulated more in cells that translocated inside of the pristane (C19) phase than in those located at the aqueous-alkane interface attached to the n-dodecane (C12) surface. PR4 (pK4-EL2-1) and PR4 (pK4-?EL2-1) strains were constructed to confirm the effects of the upregulation of GroEL2 in translocated cells. The expression of GroEL2 in PR4 (pK4-EL2-1) was 15.5-fold higher than that in PR4 (pK4-?EL2-1) in two phase cultures containing C12. The growth and cell surface lipophilicity of PR4 were enhanced by the introduction of pK4-EL2-1. These results suggested that the plasmid overexpression of groEL2 in PR4 (pK4-EL2-1) led to changes in cell localization, enhanced growth, and increased cell surface lipophilicity. Thus, we concluded that the overexpression of GroEL2 may play an important role in increasing the organic solvent tolerance of R. erythropolis PR4 in aqueous-alkane two phase cultures. PMID:25311591

  15. Interaction of alkanes with unsaturated metal centers. 2. Complexes of alkanes and fluoroalkanes with W(CO) sub 5 in the gas phase

    SciTech Connect

    Brown, C.E.; Ishikawa, Yoichi; Hackett, P.A.; Rayner, D.M. (National Research Council Canada, Ottawa, Ontario (Canada))

    1990-03-28

    Time-resolved infrared spectroscopy has been used to study the interaction of a range of open-chain, cyclic, and fluorine-substituted alkanes with the 16-electron species W(CO){sub 5}. W(CO){sub 5} forms reversible complexes with all the unsubstituted alkanes studied except CH{sub 4}. The equilibrium constant K{sub p} = (W(CO){sub 5}L)/((W(CO){sub 5})p(L)), at 300 K, increases with carbon number from 610 {plus minus} 100 atm{sup {minus}1} in cyclohexane. binding energies have also been obtained through temperature studies. They are in the range 7-11 kcal mol{sup {minus}1}, again increasing with the size of the alkanes. In the case of CH{sub 4}, a binding energy K5 kcal mol{sup {minus}1} is implied by their inability to observe a complex. Correlation of the binding energies with C-H {sigma} MO stabilization energies is consistent with a simple molecular orbital picture involving formation of a 2-electron, 3-center C-H-M bond through {sigma} {yields} M electron donation.

  16. Diversity of alkane degrading bacteria associated with plants in a petroleum oil-contaminated environment and expression of alkane monooxygenase (alkB) genes

    NASA Astrophysics Data System (ADS)

    Andria, V.; Yousaf, S.; Reichenauer, T. G.; Smalla, K.; Sessitsch, A.

    2009-04-01

    Among twenty-six different plant species, Italian ryegrass (Lolium multiflorum var. Taurus), Birdsfoot trefoil (Lotus corniculatus var. Leo), and the combination of both plants performed well in a petroleum oil contaminated soil. Hydrocarbon degrading bacteria were isolated from the rhizosphere, root interior and shoot interior and subjected to the analysis of 16S rRNA, the 16S and 23S rRNA intergenic spacer region and alkane hydroxylase genes. Higher numbers of culturable, degrading bacteria were associated with Italian ryegrass, which were also characterized by a higher diversity, particularly in the plant interior. Only half of the isolated bacteria hosted known alkane hydroxylase genes (alkB and cytochrome P153-like). Our results indicated that alkB genes have spread through horizontal gene transfer, particularly in the Italian ryegrass rhizosphere, and suggested mobility of catabolic genes between Gram-negative and Gram-positive bacteria. We furthermore studied the colonization behaviour of selected hydrocarbon-degrading strains (comprising an endopyhte and a rhizosphere strain) as well as the expression of their alkane monooxygenase genes in association with Italian ryegrass. Results showed that the endophyte strain better colonized the plant, particularly the plant interior, and also showed higher expression of alkB genes suggesting a more efficient degradation of the pollutant. Furthermore, plants inoculated with the endophyte were better able to grow in the presence of diesel. The rhizosphere strain colonized primarily the rhizosphere and showed low alkB gene expression in the plant interior.

  17. CHEMISTRY 108-01 GENERAL CHEMISTRY II

    E-print Network

    Findley, Gary L.

    CHEMISTRY 108-01 GENERAL CHEMISTRY II Fall Term, 2002 10:00 - 10:50 am, MWThF CNSB 243 INSTRUCTOR-1835 Email: findley@ulm.edu URL: www.ulm.edu/chemistry/findley COURSE Content: Principles of modern chemistry. Goals/ Objectives: CHEM 108 is the second semester of a fundamental introduction to chemistry

  18. CHEMISTRY 107-01 GENERAL CHEMISTRY I

    E-print Network

    Findley, Gary L.

    CHEMISTRY 107-01 GENERAL CHEMISTRY I Spring 2002 8:00 am - 8:50 am, MTuWTh Rm. CNSB 243 INSTRUCTOR-1835 Email: chfindley@ulm.edu URL: http://www.ulm.edu/chemistry/findley COURSE Content: Principles of modern chemistry. Goals/ Objectives: CHEM 107 is the first semester of a fundamental introduction to chemistry

  19. Chem 681 Quantum Chemistry Chemistry 681

    E-print Network

    ]. The physical chemistry text by McQuarrie & Simon [3] (used in Chem 390) also has relevant material. The third] McQuarrie and Simon, Physical Chemistry (University Science Books). [4] R.P. Feynman, R.B. LeightonChem 681 Quantum Chemistry Chemistry 681 Introduction to Quantum Chemistry Fall 2003 BIBLIOGRAPHY

  20. CHEMISTRY 321 PHYSICAL CHEMISTRY LABORATORY I

    E-print Network

    Findley, Gary L.

    CHEMISTRY 321 PHYSICAL CHEMISTRY LABORATORY I Fall 2009 2:00 - 5:00 pm, F CNSB 142 INSTRUCTOR techniques of physical chemistry. Goals/ Objectives: Physical Chemistry Laboratory introduces the student analysis software and IEEE-488 electronic devices. The focus for Physical Chemistry Laboratory I

  1. CHEMISTRY 323 PHYSICAL CHEMISTRY LABORATORY II

    E-print Network

    Findley, Gary L.

    CHEMISTRY 323 PHYSICAL CHEMISTRY LABORATORY II Spring 2010 2:00 - 5:00 pm, F CNSB 142 INSTRUCTOR techniques of physical chemistry. Goals/ Objectives: Physical Chemistry Laboratory introduces the student analysis software and IEEE-488 electronic devices. The focus for Physical Chemistry Laboratory II

  2. Chemistry Now

    NSDL National Science Digital Library

    2012-08-17

    The National Science Foundation (NSF) recently teamed up with NBC and the National Science Teachers Association to celebrate the International Year of Chemistry. Their big joint project was to create Chemistry Now, a weekly online video series that uncovers and explains the science of common, physical objects. There are over two dozen short films here that cover topics like the chemistry of salt, grapheme, safety glass, and the common cheeseburger. All of the videos are lively and interesting, and they can be used in a wide range of classroom settings to provide visual and audio reinforcement of topics that might be addressed in course lectures and other activities. The videos are completely free and the site includes links to other organizations that have created similar videos.

  3. Chemistry & Industry

    NSDL National Science Digital Library

    1997-01-01

    Chemistry and Industry Magazine, a bimonthly product of the Society of Chemical Industry, provides selected full-text articles from the print magazine in the areas of news, commentary, features, latest results from chemical literature, and highlights from the latest European patents. In addition, there is a searchable and browsable archive of past issues, a daily news section, and searchable jobs and meetings databases. The Society of Chemical Industry is "an international association of about 6000 members aimed at furthering applied chemistry." One of the highlights of its web site is its publication section, where, under "electronic publications," readers can find updated daily news, jobs and meetings listings on chemistry, pharmaceuticals, biotechnology, and the environment.

  4. Polymer Chemistry

    NASA Technical Reports Server (NTRS)

    Williams, Martha; Roberson, Luke; Caraccio, Anne

    2010-01-01

    This viewgraph presentation describes new technologies in polymer and material chemistry that benefits NASA programs and missions. The topics include: 1) What are Polymers?; 2) History of Polymer Chemistry; 3) Composites/Materials Development at KSC; 4) Why Wiring; 5) Next Generation Wiring Materials; 6) Wire System Materials and Integration; 7) Self-Healing Wire Repair; 8) Smart Wiring Summary; 9) Fire and Polymers; 10) Aerogel Technology; 11) Aerogel Composites; 12) Aerogels for Oil Remediation; 13) KSC's Solution; 14) Chemochromic Hydrogen Sensors; 15) STS-130 and 131 Operations; 16) HyperPigment; 17) Antimicrobial Materials; 18) Conductive Inks Formulations for Multiple Applications; and 19) Testing and Processing Equipment.

  5. Glucosinolate degradation products, alkanes and fatty acids from plants and cell cultures of Descurainia sophia

    Microsoft Academic Search

    S. Afsharypuor; G. B. Lockwood

    1985-01-01

    Allyl and 3-butenyl isothiocyanate with two nitriles and an epithiobutane derivative were estimated. These glucosinolate degradation products were found in callus, seed, and dried plant but not in suspension cultures. Seventeen alkanes and five fatty acids were also identified and estimated in plant material and cultures. 4-Methylthiobutyl and 2-phenylethyl isothiocyanates were also detected in seeds. Incubation of cultures at 4

  6. Biosurfactant-mediated biodegradation of straight and methyl-branched alkanes by Pseudomonas aeruginosa ATCC 55925

    PubMed Central

    2011-01-01

    Accidental oil spills and waste disposal are important sources for environmental pollution. We investigated the biodegradation of alkanes by Pseudomonas aeruginosa ATCC 55925 in relation to a rhamnolipid surfactant produced by the same bacterial strain. Results showed that the linear C11-C21 compounds in a heating oil sample degraded from 6% to 100%, whereas the iso-alkanes tended to be recalcitrant unless they were exposed to the biosurfactant; under such condition total biodegradation was achieved. Only the biodegradation of the commercial C12-C19 alkanes could be demonstrated, ranging from 23% to 100%, depending on the experimental conditions. Pristane (a C19 branched alkane) only biodegraded when present alone with the biosurfactant and when included in an artificial mixture even without the biosurfactant. In all cases the biosurfactant significantly enhanced biodegradation. The electron scanning microscopy showed that cells depicted several adaptations to growth on hydrocarbons, such as biopolymeric spheres with embedded cells distributed over different layers on the spherical surfaces and cells linked to each other by extracellular appendages. Electron transmission microscopy revealed transparent inclusions, which were associated with hydrocarbon based-culture cells. These patterns of hydrocarbon biodegradation and cell adaptations depended on the substrate bioavailability, type and length of hydrocarbon. PMID:21906343

  7. Anaerobic biodegradation of long-chain n-alkanes under sulfate-reducing conditions

    SciTech Connect

    Caldwell, M.E.; Suflita, J.M. [Univ. of Oklahoma, Norman, OK (United States). Dept. of Botany and Microbiology] [Univ. of Oklahoma, Norman, OK (United States). Dept. of Botany and Microbiology; Garrett, R.M.; Prince, R.C. [Exxon Research and Engineering Co., Annandale, NJ (United States)] [Exxon Research and Engineering Co., Annandale, NJ (United States)

    1998-07-15

    The ability of anaerobic microorganisms to degrade a wide variety of crude oil components was investigated using chronically hydrocarbon-contaminated marine sediments as the source of inoculum. When sulfate reduction was the predominant electron-accepting process, gas chromatographic analysis revealed almost complete n-alkane removal (C{sub 15}-C{sub 34}) from a weathered oil within 201 d of incubation. No alteration of the oil was detected in sterile control incubations or when nitrate served as an alternate electron acceptor. The amount of sulfate reduced in the oil-amended nonsterile incubations was more than enough to account for the complete mineralization of the n-alkane fraction of the oil; no loss of this anion was observed in sterile control incubations. The mineralization of the alkanes was confirmed using {sup 14}C-14,15-octacosane (C{sub 28}H{sub 58}), with 97% of the radioactivity recovered as {sup 14}CO{sub 2}. These findings extend the range of hydrocarbons known to be amenable to anaerobic biodegradation. Moreover, the rapid and extensive alteration in the n-alkanes can no longer be considered a defining characteristic of aerobic oil biodegradation processes alone.

  8. Volatile Alkanes and Increased Concentrations of Isoprene in Exhaled Air during Hemodialysis

    Microsoft Academic Search

    Enrico Capodicasa; Gianfranco Trovarelli; Gianna Evelina De Medio; Maria Antonietta Pelli; Giorgio Lippi; Claudio Verdura; Mario Timio

    1999-01-01

    In this study we examined breath volatile hydrocarbon concentrations in exhaled air of hemodialysis patients. We assessed both C2C5 alkanes among them ethane and pentane the production of which in man is essentially due to the action free radicals exert on polyunsaturated fatty acids and isoprene, an unsaturated hydrocarbon the biosynthesis and biological effects of which are the

  9. Correlation of high-pressure thermal conductivity, viscosity, and diffusion coefficients for n-alkanes

    Microsoft Academic Search

    M. J. Assael; J. H. Dymond; V. Tselekidou

    1990-01-01

    Thermal conductivity, viscosity, and self-diffusion coefficient data for liquid n-alkanes are satisfactorily correlated simultaneously by a method based on the hard-sphere theory of transport properties. Universal curves are developed for the reduced transport properties lambda *, eta *, and D * as a function of the reduced volume. A consistent set of equations is derived for the characteristic volume and

  10. Correlation of high-pressure diffusion and viscosity coefficients for n-alkanes

    Microsoft Academic Search

    J. H. Dymond; M. A. Awan

    1989-01-01

    Self-diffusion coefficient and viscosity coefficient data for liquid n-alkanes over the whole pressure range at different temperatures are satisfactorily correlated simultaneously by a method which is just an extension of that previously used to apply the smooth hard-sphere theory of transport properties to individual transport coefficients. Universal curves are developed for reduced quantities D * and eta * as a

  11. Correlation of high-pressure thermal conductivity, viscosity, and diffusion coefficients for n -alkanes

    Microsoft Academic Search

    M. J. Assael; J. H. Dymond; V. Tselekidou

    1990-01-01

    Thermal conductivity, viscosity, and self-diffusion coefficient data for liquid n-alkanes are satisfactorily correlated simultaneously by a method based on the hard-sphere theory of transport properties. Universal curves are developed for the reduced transport properties ?*, ?*, and D* as a function of the reduced volume. A consistent set of equations is derived for the characteristic volume and for the parameters

  12. Immunogenecity of Modified Alkane Polymers Is Mediated through TLR1/2 Activation

    PubMed Central

    Crisi, Giovanna M.; Cobelli, Neil; Santambrogio, Laura

    2008-01-01

    Background With the advancement of biomedical technology, artificial materials have been developed to replace diseased, damaged or nonfunctional body parts. Among such materials, ultra high molecular weight alkane or modified alkyl polymers have been extensively used in heart valves, stents, pacemakers, ear implants, as well as total joint replacement devices. Although much research has been undertaken to design the most non-reactive biologically inert polyethylene derivatives, strong inflammatory responses followed by rejection and failure of the implant have been noted. Methodology/Principal Findings Purification of the alkane polymers from the site of inflammation revealed extensive in vivo oxidation as detected by fourier transformed infra-red spectroscopy. Herein, we report the novel observation that oxidized alkane polymers induced activation of TLR1/2 pathway as determined by ligand dependent changes in intrinsic tyrosine fluorescence intensity and NF-?? luciferase gene assays. Oxidized polymers were very effective in activating dendritic cells and inducing secretion of pro-inflammatory cytokines. Molecular docking of the oxidized alkanes designated ligand specificity and polymeric conformations fitting into the TLR1/2 binding grooves. Conclusion/Significance This is the first report of a synthetic polymer activating immune responses through TLR binding. PMID:18560588

  13. Solvent isotope effects on alkane formation by cyanobacterial aldehyde deformylating oxygenase and their mechanistic implications.

    PubMed

    Waugh, Matthew W; Marsh, E Neil G

    2014-09-01

    The reaction catalyzed by cyanobacterial aldehyde deformylating oxygenase is of interest both because of its potential application to the production of biofuels and because of the highly unusual nature of the deformylation reaction it catalyzes. Whereas the proton in the product alkane derives ultimately from the solvent, the identity of the proton donor in the active site remains unclear. To investigate the proton transfer step, solvent isotope effect (SIE) studies were undertaken. The rate of alkane formation was found to be maximal at pH 6.8 and to be the same in D2O or H2O within experimental error, implying that proton transfer is not a kinetically significant step. However, when the ratio of protium to deuterium in the product alkane was measured as a function of the mole fraction of D2O, a (D2O)SIEobs of 2.19 0.02 was observed. The SIE was invariant with the mole fraction of D2O, indicating the involvement of a single protic site in the reaction. We interpret this SIE as most likely arising from a reactant state equilibrium isotope effect on a proton donor with an inverse fractionation factor, for which ? = 0.45. These observations are consistent with an iron-bound water molecule being the proton donor to the alkane in the reaction. PMID:25142631

  14. Fe-Catalyzed Oxidation Reactions of Olefins, Alkanes, and Alcohols: Involvement of Oxo- and Peroxo Complexes

    NASA Astrophysics Data System (ADS)

    Schrder, Kristin; Junge, Kathrin; Bitterlich, Bianca; Beller, Matthias

    In this review, recent developments of iron-catalyzed oxidations of olefins (epoxidation), alkanes, arenes, and alcohols are summarized. Special focus is given on the ligand systems and the catalytic performance of the iron complexes. In addition, the mechanistic involvement of high-valent iron-oxo species is discussed.

  15. Z .Fluid Phase Equilibria 150151 1998 151159 Thermal diffusion in alkane binary mixtures

    E-print Network

    Dysthe, Dag Kristian

    Z .Fluid Phase Equilibria 150151 1998 151159 Thermal diffusion in alkane binary mixtures the thermal conductivity and the thermal diffusion coefficient a in a methane-n-decane binary mixture in the in organic binary mixtures in order to give `experimental-like' data for the thermal diffusion factor

  16. Effects of conformational isomerism on the desorption kinetics of n-alkanes from graphite

    E-print Network

    Gellman, Andrew J.

    -alkane with the minimum free energy at the desorption temperature. These results reveal that conformational isomerism also find that Edes has a nonlinear dependence on chain length and takes the empirical form Edes a b exponent in empirical fit I. INTRODUCTION The molecular structure and dynamics of macromolecu- lar films

  17. METHYL-BRANCHED ALKANES OF THE ADULT FLEA BEETLES, APHTHONA LACERTOSA AND APHTHONA NIGRISCUTIS

    Technology Transfer Automated Retrieval System (TEKTRAN)

    An analysis was conducted of the hydrocarbon fraction of the cuticular waxes from two introduced biocontrol agents of leafy spurge, Aphthona lacertosa and A. nigriscutis. The adult beetles had a complex mixture of hydrocarbons on their cuticular surface consisting of alkanes, methylalkanes, alkenes...

  18. Determination of Alkane Content in Fresh Fecal Samples to Estimate Intake on Pasture

    Technology Transfer Automated Retrieval System (TEKTRAN)

    External markers of wax alkanes C32 and C36 are effective tools for determining intake of grazing animals. The technique requires daily dosing of markers which is impractical under extensive grazing conditions, so controlled release capsules (CRC) have been used. However, consistency of payout from ...

  19. Melting of Rodlike Molecules on Pt(111). Infrared Spectroscopic Studies of Isotopically Labeled n-Alkanes

    E-print Network

    Girolami, Gregory S.

    Melting of Rodlike Molecules on Pt(111). Infrared Spectroscopic Studies of Isotopically Labeled n 61801 ReceiVed: May 12, 1998; In Final Form: August 24, 1998 The melting of monolayers of isotopically labeled n-alkanes on Pt(111) surfaces has been followed by reflection-absorption infrared (RAIR

  20. Technical Note: n-Alkane lipid biomarkers in loess: post-sedimentary or syn-sedimentary?

    NASA Astrophysics Data System (ADS)

    Zech, M.; Kreutzer, S.; Goslar, T.; Meszner, S.; Krause, T.; Faust, D.; Fuchs, M.

    2012-07-01

    There is an ongoing discussion whether n-alkane biomarkers - and organic matter (OM) from loess in general - reflect a syn-sedimentary paleoenvironmental and paleoclimate signal or whether they are significantly a post-sedimentary feature contaminated by root-derived OM. We present first radiocarbon data for the n-alkane fraction of lipid extracts and for the first time luminescence ages for the Middle to Late Weichselian loess-paleosol sequence of Gleina in Saxony, Germany. Comparison of these biomarker ages with sedimentation ages as assessed by optically stimulated luminescence (OSL) dating shows that one n-alkane sample features a syn-sedimentary age (14C: 29.2 1.4 kyr cal BP versus OSL: 27.3 3.0 kyr). By contrast, the 14C ages derived from the other n-alkane samples are clearly younger (20.3 0.7 kyr cal BP, 22.1 0.7 kyr cal BP and 29.8 1.4 kyr cal BP) than the corresponding OSL ages (26.6 3.1 kyr, 32.0 3.5 kyr and 45.6 5.3 kyr). This finding suggests that a post-sedimentary n-alkane contamination presumably by roots has occurred. In order to estimate the post-sedimentary n-alkane contamination more quantitatively, we applied a 14C mass balance calculation based on the measured pMC (percent modern carbon) values, the calculated syn-sedimentary pMC values and pMC values suspected to reflect likely time points of post-sedimentary contamination (current, modern, 3 kyr, 6 kyr and 9 kyr). Accordingly, current and modern root-contamination would account for up to 7%, a 3 kyr old root-contamination for up to 10%, and an Early and Middle Holocene root-contamination for up to 20% of the total sedimentary n-alkane pool. We acknowledge and encourage that these first radiocarbon results need further confirmation both from other loess-paleosol sequences and for different biomarkers, e.g. carboxylic acids or alcohols as further lipid biomarkers.

  1. Investigating C4 Grass Contributions to N-alkane Based Paleoclimate Reconstructions

    NASA Astrophysics Data System (ADS)

    Doman, C. E.; Enders, S. K.; Chadwick, O.; Freeman, K. H.

    2014-12-01

    Plant wax n-alkanes are long-chain, saturated hydrocarbons contained within the protective waxy cuticle on leaves. These lipids are pervasive and persistent in soils and sediments and thus are ideal biomarkers of ancient terrestrial organic matter. In ecosystems dominated by C3 plants, the relationship between the carbon isotopic value of whole leaves and lipids is fairly well documented, but this relationship has not been fully investigated for plants that use C4 photosynthesis. In both cases, it is unclear if the isotopic relationships are sensitive to environmental conditions, or reflect inherited characteristics. This study used a natural climate gradient on the Kohala peninsula of Hawaii to investigate relationships between climate and the ?13C and ?2H values of n-alkanes in C3 and C4 plants. ?13C of C3 leaves and lipids decreased 5 from the driest to the wettest sites, consistent with published data. Carbon isotope values of C4 plants showed no relationship to moisture up to 1000 mm mean annual precipitation (MAP). Above this threshold, ? 13C values were around 10 more depleted, likely due to a combination of canopy effects and C4 grasses growing in an uncharacteristically wet and cold environment. In C3 plants, the fractionation between leaf and lipid carbon isotopes did not vary with MAP, which allows estimations of ?13C leaf to be made from alkanes preserved in ancient sediments. Along this transect, C3 plants produce around twice the quantity of n-alkanes as C4 grasses. C4 grasses produce longer carbon chains. As a result, n-alkanes in the geologic record will be biased towards C3 plants, but the presence of alkanes C33 and C35 indicate the contributions of C4 grasses. In both C3 and C4 plants, average chain length increased with mean annual precipitation, but the taxonomic differences in chain length were greater than environmental differences. Hydrogen isotopes of n-alkanes show no trends with MAP, but do show clear differences between plant functional types and sampled taxa. That there is no strong trend between fractionation and aridity supports the use of ?2Hlipid as a record of environmental waters at the time of lipid synthesis, provided that the relative contributions of each plant functional type can be identified using other proxies.

  2. Chemistry 320N Organic Chemistry II

    E-print Network

    Chemistry 320N Organic Chemistry II for Prehealth Professionals Unique number: 52365 Spring 2013 M students can access the information. #12;Required Text: Brown, Foote, Iverson, & Anslyn Organic Chemistry

  3. n-Alkane lipid biomarkers in loess: post-sedimentary or syn-sedimentary?

    NASA Astrophysics Data System (ADS)

    Zech, Michael; Kreutzer, Sebastian; Goslar, Tomasz; Meszner, Sascha; Krause, Tobias; Faust, Dominik; Fuchs, Markus

    2013-04-01

    There is an ongoing discussion whether n-alkane biomarkers - and organic matter (OM) from loess in general - reflect a syn-sedimentary paleoenvironmental and paleoclimate signal or whether they are significantly a post-sedimentary feature contaminated by root-derived OM (Zech et al., 2012, 2013; Wiesenberg and Gocke, 2013). We present first radiocarbon data for the n-alkane fraction of lipid extracts and for the first time luminescence ages for the Middle to Late Weichselian loess-paleosol sequence of Gleina in Saxony, Germany. Comparison of these biomarker ages with sedimentation ages as assessed by optically stimulated luminescence (OSL) dating shows that one n-alkane sample features a syn-sedimentary age (14C: 29.2 1.4 kyr calBP versus OSL: 27.3 3.0 kyr). By contrast, the 14C ages derived from the other n-alkane samples are clearly younger (20.3 0.7 kyr calBP, 22.1 0.7 kyr calBP and 29.8 1.4 kyr calBP) than the corresponding OSL ages (26.6 3.1 kyr, 32.0 3.5 kyr and 45.6 5.3 kyr). This finding suggests that a post-sedimentary n-alkane contamination presumably by roots has occurred. In order to estimate the post-sedimentary n-alkane contamination more quantitatively, we applied a 14C mass balance calculation based on the measured pMC (percent modern carbon) values, the calculated syn-sedimentary pMC values and pMC values suspected to reflect likely time points of post-sedimentary contamination (modern, last decades, 3 kyr, 6 kyr and 9 kyr). Accordingly, modern and last decadal root-contamination would account for up to 7%, a 3 kyr old root-contamination for up to 10%, and an Early and Middle Holocene root-contamination for up to 20% of the total sedimentary n-alkane pool. We acknowledge and encourage that these first radiocarbon results need further confirmation both from other loess-paleosol sequences and for different biomarkers, e.g. carboxylic acids or alcohols as further lipid biomarkers. Zech, M., Kreutzer, S., Goslar, T., Meszner, S., Krause, T., Faust, D. and Fuchs, M., 2012: Technical Note: n-Alkane lipid biomarkers in loess: post-sedimentary or syn-sedimentary? Biogeosciences Discussions 9, 9875-9896. Wiesenberg, G. and Gocke, M., 2013. Comment of G. Wiesenberg and M. Gocke on "Reconstruction of the late Quaternary paleoenvironments of the Nussloch loess paleosol sequence, Germany, using n-alkane biomarkers. Quaternary Research, in press. Zech, M., Rass, S., Buggle, B., Lscher, M. and Zller, L.. 2013. Response to the comment of G. Wiesenberg and M. Gocke on "Reconstruction of the late Quaternary paleoenvironments of the Nussloch loess paleosol sequence, Germany, using n-alkane biomarkers". Quaternary Research, in press.

  4. Chemistry Notes

    ERIC Educational Resources Information Center

    School Science Review, 1976

    1976-01-01

    Describes several chemistry projects, including solubility, formula for magnesium oxide, dissociation of dinitrogen tetroxide, use of 1-chloro-2, 4-dinitrobenzene, migration of ions, heats of neutralizations, use of pocket calculators, sonic cleaning, oxidation states of manganese, and cell potentials. Includes an extract from Chemical Age on

  5. Nuclear Chemistry

    NSDL National Science Digital Library

    This page, from the University of North Carolina - Chapel Hill Chemistry Fundamentals program and the Shodor Education Foundation, discusses five different types of radioactive decay: alpha, beta negative, gamma, positron emission, and electron capture. After examining the numerous equations, students can test their dating skills by solving three practice problems. Solutions are included.

  6. Chemistry Notes.

    ERIC Educational Resources Information Center

    School Science Review, 1980

    1980-01-01

    Presents 12 chemistry notes for British secondary school teachers. Some of these notes are: (1) a simple device for testing pH-meters; (2) portable fume cupboard safety screen; and (3) Mass spectroscopy-analysis of a mass peak. (HM)

  7. Chemistry Notes.

    ERIC Educational Resources Information Center

    School Science Review, 1978

    1978-01-01

    Describes some laboratory apparatus, chemistry experiments and demonstrations, such as a Kofler block melting point apparatus, chromatographic investigation of the phosphoric acid, x-ray diffraction, the fountain experiment, endothermic sherbet, the measurement of viscosity, ionization energies and electronic configurations. (GA)

  8. Green Chemistry

    NSDL National Science Digital Library

    WGBH Educational Foundation

    2010-02-12

    This audio segment from PRI's The World Science Podcast explores the science of Green Chemistry. Hear about companies that are developing greener chemicals, and learn why they are fast becoming an attractive alternative for the multi-billion dollar chemical industry.

  9. Countertop Chemistry

    NSDL National Science Digital Library

    Chemistry activities and demonstrations that use common household items and kitchen chemicals. There are activities appropriate for students in elementary school, middle school, and high school. The activities were designed and tested by the Science House, the science and mathematics learning outreach program of North Carolina State University.

  10. Chemistry Activities

    NSDL National Science Digital Library

    This collection of resource features demonstrations, laboratory investigations, teaching tips, worksheets and other chemistry-related activities. Materials include investigations of mols, nuclear energy, the periodic table, weight and mass, elements, calculations, equations, pH, atomic weight, half-lives, and reactions.

  11. Analytical Chemistry

    NSDL National Science Digital Library

    Hardy, James K.

    This site features lecture notes for first and second level courses in analytical chemistry. Topics include titrations, gravimetry, kinetics and electrochemistry (redox). Potentiometry, coulometry, voltammetry, spectroscopic and separation methods are presented as well, and are illustrated with QuickTime animations.

  12. Common Chemistry

    NSDL National Science Digital Library

    Chemical Abstracts Service (CAS)

    A web resource that contains Chemical Abstracts Service (CAS) Registry Numbers for approximately 7,800 chemicals of widespread general public interest. Common Chemistry is helpful to non-chemists who know either a name or CAS Registry Number of a common chemical and want to pair both pieces of information.

  13. Atmospheric Chemistry

    NSDL National Science Digital Library

    This set of links provides access to resources on atmospheric chemistry, especially acid deposition, air pollution, and air quality. The sites include personal and government pages, universities and research groups, non-governmental organizations and meetings, and products and services. There are also links to related search topics.

  14. Chemistry Notes

    ERIC Educational Resources Information Center

    School Science Review, 1972

    1972-01-01

    Short articles on the kinetics of the hydrogen peroxide-iodide ion reaction, simulation of fluidization catalysis, the use of Newman projection diagrams to represent steric relationships in organic chemistry, the use of synthetic substrates for proteolytic enzyme reactions, and two simple clock reactions"--hydrolysis of halogenoalkanes and

  15. Patterns of phase behavior in ternary ethoxylated alcohol-n-alkane-water mixtures

    SciTech Connect

    Kilpatrick, P.K.; Gorman, C.A.; Davis, H.T.; Scriven, L.E.; Miller, W.G.

    1986-10-09

    Certain ternary mixtures of ethoxylated alcohols, n-alkanes, and water at 25/sup 0/C separate at equilibrium into three liquid phases. The development of an amphiphile-rich middle phase is sensitive to alcohol molecular weight, alkane carbon number (ACN), and temperature. A middle phase arises when all three variables are adjusted such that the alcohol has no preference to partition into either an oleic or aqueous phase. A change in one of these variables yields a sequence of ternary phase diagrams in which the range of the three phases is from one critical tie line to a second. There are two distinct patterns, however, in which the critical tie lines arise. With a low molecular weight ethoxylated alcohol, both critical tie lines lie in the miscibility gap between water-rich and alkane-rich phases. With larger ethoxylated alcohols, however, one of the critical tie lines arises from the fusion of that miscibility gap with the critical point on a second one between water-rich and alcohol-rich phases. Both patterns are modeled well by modifying the Flory-Huggins equation of state to account for the tendency of amphiphile to concentrate between water-rich and alkane-rich domains, thereby attenuating or screening the enthalpic repulsion between water and alkane. The screening is expressed by a factor which is exponential in amphiphile concentration. The type of three-phase equilibria which arises from fusion of two miscibility gaps requires a pair of screening factors. Other available thermodynamic models appear incapable of approximating this second pattern of three-phase equilibria.

  16. Fall 2011 Chemistry 676

    E-print Network

    Mather, Patrick T.

    Fall 2011 Chemistry 676 "Introduction to organic synthesis: Methodology" T chemistry, olefination reactions, cross coupling chemistry, and modern transition metal are due by 1200 (noon) in my office (CST 3-008) or my mailbox in the chemistry

  17. Adaptation of the hydrocarbonoclastic bacterium Alcanivorax borkumensis SK2 to alkanes and toxic organic compounds: a physiological and transcriptomic approach.

    PubMed

    Naether, Daniela J; Slawtschew, Slavtscho; Stasik, Sebastian; Engel, Maria; Olzog, Martin; Wick, Lukas Y; Timmis, Kenneth N; Heipieper, Hermann J

    2013-07-01

    The marine hydrocarbonoclastic bacterium Alcanivorax borkumensis is able to degrade mixtures of n-alkanes as they occur in marine oil spills. However, investigations of growth behavior and physiology of these bacteria when cultivated with n-alkanes of different chain lengths (C6 to C30) as the substrates are still lacking. Growth rates increased with increasing alkane chain length up to a maximum between C12 and C19, with no evident difference between even- and odd-numbered chain lengths, before decreasing with chain lengths greater than C19. Surface hydrophobicity of alkane-grown cells, assessed by determination of the water contact angles, showed a similar pattern, with maximum values associated with growth rates on alkanes with chain lengths between C11 and C19 and significantly lower values for cells grown on pyruvate. A. borkumensis was found to incorporate and modify the fatty acid intermediates generated by the corresponding n-alkane degradation pathway. Cells grown on distinct n-alkanes proved that A. borkumensis is able to not only incorporate but also modify fatty acid intermediates derived from the alkane degradation pathway. Comparing cells grown on pyruvate with those cultivated on hexadecane in terms of their tolerance toward two groups of toxic organic compounds, chlorophenols and alkanols, representing intensely studied organic compounds, revealed similar tolerances toward chlorophenols, whereas the toxicities of different n-alkanols were significantly reduced when hexadecane was used as a carbon source. As one adaptive mechanism of A. borkumensis to these toxic organic solvents, the activity of cis-trans isomerization of unsaturated fatty acids was proven. These findings could be verified by a detailed transcriptomic comparison between cultures grown on hexadecane and pyruvate and including solvent stress caused by the addition of 1-octanol as the most toxic intermediate of n-alkane degradation. PMID:23645199

  18. Methanol conversion to higher hydrocarbons

    SciTech Connect

    Tabak, S.A. [Mobil Research and Development Corp., Princeton, NJ (United States). Central Research Lab.

    1994-12-31

    Several indirect options exist for producing chemicals and transportation fuels from coal, natural gas, or biomass. All involve an initial conversion step to synthesis gas (CO and H{sub 2}). Presently, there are two commercial technologies for converting syngas to liquids: Fischer-Tropsch, which yields a range of aliphatic hydrocarbons with molecular weights determined by Schulz-Flory kinetics, and methanol synthesis. Mobil`s diversity of technology for methanol conversion gives the methanol synthesis route flexibility for production of either gasoline, distillate or chemicals. Mobil`s ZSM-5 catalyst is the key in several processes for producing chemicals and transportation fuels from methanol: MTO for light olefins, MTG for gasoline, MOGD for distillates. The MTG process has been commercialized in New Zealand since 1985, producing one-third of the country`s gasoline supply, while MTO and MOGD have been developed and demonstrated at greater than 100 BPD scale. This paper will discuss recent work in understanding methanol conversion chemistry and the various options for its use.

  19. Robert M. Corn Department of Chemistry

    E-print Network

    and technological areas such as electroanalytical chemistry, heterogeneous catalysis, solar energy conversion) are polarization vectors describing the input and output light fields, respectively (I).Because x re- lates two polarization, out- put polarization, incident angle, and (for anisotropic surfaces) azimuthal angle

  20. UNIVERSITY OF BUCHAREST FACULTY OF CHEMISTRY

    E-print Network

    Paris-Sud XI, Universit de

    in the total oxidation of propane as a VOC model. Chapter III is focussed on the study of oxidation catalystsUNIVERSITY OF BUCHAREST FACULTY OF CHEMISTRY CATALYSIS BY OXIDES: CONVERSION OF LIGHT ORGANIC in the field of Catalysis by Oxides by grouping it on a thematic basis. Consequently, each chapter in Section

  1. The Genes rubA and rubB for Alkane Degradation in Acinetobacter sp. Strain ADP1 Are in an Operon with estB, Encoding an Esterase, and oxyR

    Microsoft Academic Search

    WALTER GEIDORFER; RUBEN G. KOK; ANDREAS RATAJCZAK; KLAAS J. HELLINGWERF; WOLFGANG HILLEN; BioCentrum Amsterdam

    1999-01-01

    Alkanes are oxidized in Acinetobacter sp. strain ADP1 by a three-component alkane monooxygenase, com- posed of alkane hydroxylase, rubredoxin, and rubredoxin reductase. rubA and rubB encode rubredoxin and a NAD(P)H-dependent rubredoxin reductase. We demonstrate here that single base pair substitutions in rubA or rubB lead to defects in alkane degradation, showing that both genes are essential for alkane utilization. Differences

  2. Resin Chemistry

    Microsoft Academic Search

    Louis Pilato

    2010-01-01

    \\u000a During the ensuing years since the last phenolic resins book was published, many new and remarkable developments have occurred\\u000a in the realm of phenolic chemistry and are given in this chapter.\\u000a \\u000a \\u000a A critical examination of the first step or addition step (methylolation) in the preparation of resoles is described and how\\u000a it can be controlled and compared with the typical

  3. An Explanation for the Enhanced Activity for Light Alkane Conversion in Mildly Steam Dealuminated Mordenite: The Dominant Role of Adsorption

    Microsoft Academic Search

    J. A. van Bokhoven; M. Tromp; D. C. Koningsberger; J. T. Miller; J. A. Z. Pieterse; J. A. Lercher; B. A. Williams; H. H. Kungx

    2001-01-01

    This paper presents a catalytic, spectroscopic, calorimetric study of mildly steam-dealuminated mordenite (H-MOR). With increasing steam partial pressures at 673 K there is increasing dealumination, the loss of Brnsted acid sites and the presence of extra-framework Al (AlEF) likely in the zeolite pores. Additionally, the number of Lewis sites increases with increasing AlEF. As observed in previous studies, the catalytic

  4. Chemistry 411/611 Inorganic Chemistry (2010)

    E-print Network

    Mather, Patrick T.

    2010-01-01

    1 Chemistry 411/611 Inorganic Chemistry (2010) Instructor: Assistant Professor Mathew M. Maye: M-W 4:00-5:00, and by appointment Credits: 3 Text: (Required) Shriver & Atkins, "Inorganic Chemistry. (Suggested for CHE611 Students pursuing Inorganic) Huheey, "Inorganic Chemistry: Principles of Structure

  5. CHEMISTRY 3022-63067 PHYSICAL CHEMISTRY II

    E-print Network

    Findley, Gary L.

    CHEMISTRY 3022-63067 PHYSICAL CHEMISTRY II Spring 2014 8:00 am - 8:50 am, MWF CNSB 211 INSTRUCTOR interpretations of the physical principles of chemistry. Goals/ Objectives: CHEM 3022 presents chemical principles: Physical Chemistry, R. Stephen Berry, Stuart A. Rice and John Ross, 2nd ed. (Oxford Univ. Press, New York

  6. CHEMISTRY 1010 CHEMISTRY, HUMANITY AND ENVIRONMENT

    E-print Network

    Simons, Jack

    CHEMISTRY 1010 CHEMISTRY, HUMANITY AND ENVIRONMENT Spring 2006 Instructor: Dr. Laya Kesner, HEB - 002 H ST 205 11:50 a.m.-12:40 p.m. Teaching Assistant: Chem 1010-002 Michelle Taliaferro, michelle@chemistry; 9:30 a.m. - 5:30 p.m. Textbook: Chemistry for Changing Times, 10th Edition, Hill & Kolb, Prentice

  7. Chemistry 211 General Chemistry Laboratory II

    E-print Network

    Nickrent, Daniel L.

    Chemistry 211 General Chemistry Laboratory II Fall 2014 Instructor Dr. Michelle Greene Office: Neckers 295 Office Hours: by appointment Phone: TBA E-mail: mgreene@chem.siu.edu Text Chemistry 211 University Carbondale) Course Description "General Chemistry Laboratory II" is an introductory level

  8. CHEMISTRY 162 GENERAL CHEMISTRY II SPRING 2008

    E-print Network

    Vonessen, Nikolaus

    1 of 10 CHEMISTRY 162 GENERAL CHEMISTRY II SPRING 2008 Lead Instructor Professor Mark S. Cracolice survey of chemistry. We follow the standard curriculum in the United States, as suggested by the American an introduction to the principles of physical and inorganic chemistry appropriate for the level of knowledge

  9. CHEMISTRY 3020-43256 PHYSICAL CHEMISTRY I

    E-print Network

    Findley, Gary L.

    CHEMISTRY 3020-43256 PHYSICAL CHEMISTRY I Fall 2013 8:00 am - 8:50 am, MWF SUGAR 259 INSTRUCTOR interpretations of the physical principles of chemistry. Goals/ Objectives: CHEM 3020 presents chemical principles foundations of modern chemistry. Topics covered include: introduction to quantum theory, atomic structure

  10. SYLLABUS for CHEMISTRY 2310 ORGANIC CHEMISTRY 1

    E-print Network

    Simons, Jack

    SYLLABUS for CHEMISTRY 2310 ORGANIC CHEMISTRY 1 Lectures: Monday, Wednesday and Friday 8:35 AM-9 Chemistry" by Janice Gorzynski Smith, McGraw Hill, 3rd Edition, 2010 [2nd Edition will suffice]. The ebook Highly Recommended Equipment: Turning Point Clicker Highly Recommended: (1) "Organic Chemistry I

  11. CHEMISTRY 3020-42232 PHYSICAL CHEMISTRY I

    E-print Network

    Findley, Gary L.

    CHEMISTRY 3020-42232 PHYSICAL CHEMISTRY I Fall 2011 8:00 am - 8:50 am, MWF CNSB 211 INSTRUCTOR interpretations of the physical principles of chemistry. Goals/ Objectives: CHEM 3020 presents chemical principles.) REQUIREMENTS Prerequisites: "C" or better in CHEM 1008; PHYS 2008; MATH 1032. Text: Physical Chemistry, P

  12. CHEMISTRY DEPARTMENT Chem 315 (Honors Organic Chemistry)

    E-print Network

    Lawson, Catherine L.

    CHEMISTRY DEPARTMENT Chem 315 (Honors Organic Chemistry) Fall 2014 Important Registration Information Admission to Honors Organic Chemistry (Fall 2014) is restricted to the following students: Students who received an A in both semesters of General Chemistry (159 and 160 OR 161 and 162 OR 163

  13. CHEMISTRY 3022-62169 PHYSICAL CHEMISTRY II

    E-print Network

    Findley, Gary L.

    CHEMISTRY 3022-62169 PHYSICAL CHEMISTRY II Spring 2012 8:00 am - 8:50 am, MWF CNSB 211 INSTRUCTOR interpretations of the physical principles of chemistry. Goals/ Objectives: CHEM 3022, which is a continuation of CHEM 3020, focuses of the quantum theoretical foundations of modern chemistry. Topics covered include

  14. Chemistry 224 Fall 2008 Honors General Chemistry

    E-print Network

    Richmond, Geraldine L.

    Chemistry 224 Fall 2008 Honors General Chemistry Dr. Greg Williams Office hours: Onyx 182 Tu and Th 110 Required Materials: Textbook General Chemistry: Principles and Modern Applications by R. Petrucci Prerequisites: One year of high school chemistry and one year of high school physics are the minimum

  15. CHEMISTRY CONNECTION Northwestern University Department of Chemistry

    E-print Network

    Grzybowski, Bartosz A.

    CHEMISTRY CONNECTION Northwestern University Department of Chemistry In this Issue Faculty News 2. The team, representing four departments and schools at Northwestern (Chemistry, Kellogg/ Business, Law is stored in motor vehicle gas tanks. Omar Farha, Chemistry Research Associate Professor, along with Chris

  16. Position: Assistant Professor of Chemistry, Physical Chemistry

    E-print Network

    John Grey Position: Assistant Professor of Chemistry, Physical Chemistry Email: jkgrey of Physical Chemistry C (2010) ACS ASAP. 2. "Resonance Raman Spectroscopic- and Photocurrent Imaging of Polythiophene/Fullerene Solar Cells" Y.Gao, T.P. Martin, A.K. Thomas, J.K. Grey. Journal of Physical Chemistry

  17. n-Alkane hydroconversion on Zeogrid and colloidal ZSM-5 assembled from aluminosilicate nanoslabs of MFI framework type.

    PubMed

    Aerts, Alexander; Huybrechts, Ward; Kremer, Sebastien P B; Kirschhock, Christine E A; Theunissen, Elisabeth; Van Isacker, Annabel; Denayer, Joeri F M; Baron, Gino V; Thybaut, Joris W; Marin, Guy B; Jacobs, Pierre A; Martens, Johan A

    2003-08-01

    n-Alkane hydroisomerisation and hydrocracking experiments reveal that ZSM-5 materials synthesized by self-assembly of nanoslabs show different molecular shape selectivity than ZSM-5 synthesized by hydrothermal methods. PMID:12932017

  18. Changes in the concentration and relative abundance of alkanes and PAHs from the Deepwater Horizon oiling of coastal marshes.

    PubMed

    Turner, R E; Overton, E B; Meyer, B M; Miles, M S; Hooper-Bui, L

    2014-09-15

    We determined changes of 28 alkanes and 43 different PAHs in 418 wetland soil samples collected on ten sampling trips to three Louisiana estuaries before and after they were oiled from the 2010 Deepwater Horizon disaster. There was a significant decline in 22 of the 28 alkane analytes (0.42% day(-1)), no change in 6, over 2.5 years. The concentration of five aromatic petroleum hydrocarbons (PAHs) increased (range 0.25-0.70% day(-1)), whereas the total PAH pool did not change. Of these five, naphthalene and C-1-naphthalenes are suggested to be of higher toxicity than the other three because of their relatively higher volatility or solubility. The relative proportions of alkane analytes, but not PAHs, does not yet resemble that in the pre-oiled marshes after 3 years, The trajectories of nine indicators for degradation/weathering were either inconclusive or misleading (alkanes) or confirmed the relatively meager degradation of PAHs. PMID:25127500

  19. 40 CFR 721.10381 - Cyclic carboxylic acid, polymer with dihydroxy dialkyl ether, hydroxy substituted alkane and...

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ...2013-07-01 false Cyclic carboxylic acid, polymer with dihydroxy dialkyl ether, hydroxy substituted alkane and carboxylic acid anhydride, methacrylate terminated polyester...Substances 721.10381 Cyclic carboxylic acid, polymer with dihydroxy dialkyl...

  20. 40 CFR 721.10381 - Cyclic carboxylic acid, polymer with dihydroxy dialkyl ether, hydroxy substituted alkane and...

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ...2014-07-01 false Cyclic carboxylic acid, polymer with dihydroxy dialkyl ether, hydroxy substituted alkane and carboxylic acid anhydride, methacrylate terminated polyester...Substances 721.10381 Cyclic carboxylic acid, polymer with dihydroxy dialkyl...

  1. 40 CFR 721.10381 - Cyclic carboxylic acid, polymer with dihydroxy dialkyl ether, hydroxy substituted alkane and...

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ...2012-07-01 false Cyclic carboxylic acid, polymer with dihydroxy dialkyl ether, hydroxy substituted alkane and carboxylic acid anhydride, methacrylate terminated polyester...Substances 721.10381 Cyclic carboxylic acid, polymer with dihydroxy dialkyl...

  2. Test of the universality of the scaling energy in alkanes using melting transition of layer adsorbed on graphite

    NASA Astrophysics Data System (ADS)

    Kuchta, B.; Firlej, L.; Roth, M. W.; Gray, Paul A.; Wexler, Carlos

    2008-03-01

    The non-bonded terms together with the torsional energy determine the internal (conformational) degrees of freedom of simulated alkanes. Being able to predict the energy and ordering of conformations correctly is an essential quantity for bringing force field methods into the predictive regime of theoretical methods. To estimate the universality of modern force fields it is helpful to know how different components of classical fields affect the simulated properties. In the case of alkanes, the interplay between torsion potential and the scaling of 1-4 van der Waals and 1-4 charge-charge (QQ) interactions plays a crucial role. It is the purpose of this work to study universality of the scaling factor of 1-4 non-bonded interactions in alkanes. Three alkanes of length from 7 to 30 (C6, C12, C24), in an all-atom representation have been analyzed.

  3. Revisiting Mt. Kilimanjaro: Do n-alkane biomarkers in soils reflect the ?2H isotopic composition of precipitation?

    NASA Astrophysics Data System (ADS)

    Zech, M.; Zech, R.; Rozanski, K.; Hemp, A.; Gleixner, G.; Zech, W.

    2014-06-01

    During the last decade compound-specific deuterium (?2H) analysis of plant leaf wax-derived n-alkanes has become a promising and popular tool in paleoclimate research. This is based on the widely accepted assumption that n-alkanes in soils and sediments generally reflect ?2H of precipitation (?2Hprec). Recently, several authors suggested that ?2H of n-alkanes (?2H,sub>n-alkanes) can also be used as proxy in paleoaltimetry studies. Here we present results from a ?2H transect study (~1500 to 4000 m a.s.l.) carried out on precipitation and soil samples taken from the humid southern slopes of Mt. Kilimanjaro. Contrary to earlier suggestions, a distinct altitude effect in ?2Hprec is present above ~2000 m a.s.l., i.e. ?2Hprec values become more negative with increasing altitude. The compound-specific ?2H values of nC27 and nC29 do not confirm this altitudinal trend, but rather become more positive both in the O-layers (organic layers) and the Ah-horizons (mineral topsoils). Although our ?2Hn-alkane results are in agreement with previously published results from the southern slopes of Mt. Kilimanjaro (Peterse et al., 2009, BG, 6, 2799-2807), a major re-interpretation is required given that the ?2Hn-alkane results do not reflect the ?2Hprec results. The theoretical framework for this re-interpretation is based on the evaporative isotopic enrichment of leaf water associated with transpiration process. Modelling results show that relative humidity, decreasing considerably along the southern slopes of Mt. Kilimanjaro (from 78% at ~ 2000 m a.s.l. to 51% at 4000 m a.s.l.), strongly controls ?2Hleaf water. The modelled ?2H leaf water enrichment along the altitudinal transect matches well the measured 2H leaf water enrichment as assessed by using the ?2Hprec and ?2Hn-alkane results and biosynthetic fractionation during n-alkane biosynthesis in leaves. Given that our results clearly demonstrate that n-alkanes in soils do not simply reflect ?2Hprec but rather ?2Hleaf water, we conclude that care has to be taken not to over-interpret ?2Hn-alkane records from soils and sediments when reconstructing ?2H of paleoprecipitation. Both in paleoaltimetry and in paleoclimate studies changes in relative humidity and consequently in ?2Hn-alkane values can completely mask altitudinally or climatically-controlled changes in ?2Hprec.

  4. Gene Cloning and Characterization of Multiple Alkane Hydroxylase Systems in Rhodococcus Strains Q15 and NRRL B-16531

    PubMed Central

    Whyte, L. G.; Smits, T. H. M.; Labb, D.; Witholt, B.; Greer, C. W.; van Beilen, J. B.

    2002-01-01

    The alkane hydroxylase systems of two Rhodococcus strains (NRRL B-16531 and Q15, isolated from different geographical locations) were characterized. Both organisms contained at least four alkane monooxygenase gene homologs (alkB1, alkB2, alkB3, and alkB4). In both strains, the alkB1 and alkB2 homologs were part of alk gene clusters, each encoding two rubredoxins (rubA1 and rubA2; rubA3 and rubA4), a putative TetR transcriptional regulatory protein (alkU1; alkU2), and, in the alkB1 cluster, a rubredoxin reductase (rubB). The alkB3 and alkB4 homologs were found as separate genes which were not part of alk gene clusters. Functional heterologous expression of some of the rhodococcal alk genes (alkB2, rubA2, and rubA4 [NRRL B-16531]; alkB2 and rubB [Q15]) was achieved in Escherichia coli and Pseudomonas expression systems. Pseudomonas recombinants containing rhodococcal alkB2 were able to mineralize and grow on C12 to C16 n-alkanes. All rhodococcal alkane monooxygenases possessed the highly conserved eight-histidine motif, including two apparent alkane monooxygenase signature motifs (LQRH[S/A]DHH and NYXEHYG[L/M]), and the six hydrophobic membrane-spanning regions found in all alkane monooxygenases related to the Pseudomonas putida GPo1 alkane monooxygenase. The presence of multiple alkane hydroxylases in the two rhodococcal strains is reminiscent of other multiple-degradative-enzyme systems reported in Rhodococcus. PMID:12450813

  5. Stable Isotope Labeled n-Alkanes to Assess Digesta Passage Kinetics through the Digestive Tract of Ruminants

    PubMed Central

    Warner, Daniel; Ferreira, Luis M. M.; Breuer, Michel J. H.; Dijkstra, Jan; Pellikaan, Wilbert F.

    2013-01-01

    We describe the use of carbon stable isotope (13C) labeled n-alkanes as a potential internal tracer to assess passage kinetics of ingested nutrients in ruminants. Plant cuticular n-alkanes originating from intrinsically 13C labeled ryegrass plants were pulse dosed intraruminally in four rumen-cannulated lactating dairy cows receiving four contrasting ryegrass silage treatments that differed in nitrogen fertilization level (45 or 90 kg nitrogen ha?1) and maturity (early or late). Passage kinetics through the gastrointestinal tract were derived from the ?13C (i.e. the ratio 13C:12C) in apparently undigested fecal material. Isotopic enrichment was observed in a wide range of long-chain n-alkanes (C27C36) and passage kinetics were determined for the most abundant C29, C31 and C33 n-alkanes, for which a sufficiently high response signal was detected by combustion isotope ratio mass spectrometry. Basal diet treatment and carbon chain length of n-alkanes did not affect fractional passage rates from the rumen (K1) among individual n-alkanes (3.713.95%/h). Peak concentration time and transit time showed a quantitatively small, significant (p?0.002) increase with carbon chain length. K1 estimates were comparable to those of the 13C labeled digestible dry matter fraction (3.38%/h; r?=?0.61 to 0.71; p?0.012). A literature review has shown that n-alkanes are not fermented by microorganisms in the rumen and affirms no preferential depletion of 13C versus 12C. Our results suggest that 13C labeled n-alkanes can be used as nutrient passage tracers and support the reliability of the ?13C signature of digestible feed nutrients as a tool to measure nutrient-specific passage kinetics. PMID:24124493

  6. Dynamic hydrocarbon separation in high-temperature, high-pressure, liquid n-alkane water vapor systems by steam distillation

    E-print Network

    Vlierboom, Casper-Maarten

    1987-01-01

    DYNAMIC HYDROCARBON SEPARA1'ION IN HIGH-TEMPERATURE, HIGH-PRESSURE, LIQUID N-ALKANE ? WATER ? VAPOR SYSTEMS BY STEAM DISTILLATION A Thesis by CASPER-MAARTEN VLIERBOOM Submitted to the Graduate College of Texas AGM University in partial... fulfillment of the requirements for the degree of MASTER OF SCIENCE December 1987 Major Subject: Petroleum Engineering DYNAMIC HYDROCARBON SEPARATION IN HIGH TEMPERATURE HIGH PRESSURE, LIQUID N-ALKANE ? WATER ? VAPOR SYSTEMS BY STEAM DISTILLATION A...

  7. Size distribution of n-alkanes and polycyclic aromatic hydrocarbons (PAHs) in urban and rural atmospheres of Guangzhou, China

    Microsoft Academic Search

    Xinhui Bi; Guoying Sheng; Pingan Peng; Yingjun Chen; Jiamo Fu

    2005-01-01

    n-Alkanes and polycyclic aromatic hydrocarbons (PAHs) were identified in particle-sized aerosols of the urban and rural atmospheres of Guangzhou, China. Most of the organic compounds were mainly associated with fine particles with aerodynamic diameters less than 1.5?m in the urban and rural atmospheres. In the urban aerosol close to the road, about 57% of n-alkanes and 62% of PAHs were

  8. Alkane distribution and carbon isotope composition in fossil leaves: An interpretation of plant physiology in the geologic past

    NASA Astrophysics Data System (ADS)

    Graham, H. V.; Freeman, K. H.

    2014-12-01

    The relative chain-length distribution and carbon-isotope composition of n-alkanes extracted from sedimentary rocks are important geochemical tools for investigating past terrestrial ecosystems. Alkanes preserved in ancient sediments are assumed to be contemporaneous, derived from the same ecosystem, and integrated from the biomass present on the landscape at the time of deposition. Further, there is an underlying assumption that ancient plants exhibited the same metabolic and physiological responses to climate conditions that are observed for modern plants. Interpretations of alkane abundances and isotopic signatures are complicated by the strong influence of phylogenetic affiliation and ecological factors, such as canopy structure. A better understanding of how ecosystem and taxa influence alkane properties, including homologue abundance patterns and leaf-lipid carbon isotope fractionation would help strengthen paleoecological interpretations based on these widely employed plant biomarkers. In this study, we analyze the alkane chain-length distribution and carbon-isotope composition of phytoleim and alkanes (d13Cleaf and d13Clipid) extracted from a selection of Cretaceous and Paleocene fossil leaves from the Guaduas and Cerrejon Formations of Colombia. These data were compared with data for the same families in a modern analogue biome. Photosynthetic and biosynthetic fractionation (?leaf and elipid) values determined from the fossil material indicate carbon metabolism patterns were similar to modern plants. Fossil data were incorporated in a biomass-weighted mixing model to represent the expected lipid complement of sediment arising from this ecosystem and compared with alkane measurements from the rock matrix. Modeled and observed isotopic and abundance patterns match well for alkane homologs most abundant in plants (i.e., n-C27 to n-C33). The model illustrates the importance of understanding biases in litter flux and taphonomic pressures inherent in the fossil lipid record, and it highlights the influence of community composition and forest structure on sedimentary lipids.

  9. A unified single-event microkinetic model for alkane hydroconversion in different aggregation states on Pt/H-USY-zeolites.

    PubMed

    Laxmi Narasimhan, C S; Thybaut, Joris W; Martens, Johan A; Jacobs, Pierre A; Denayer, Joeri F; Marin, Guy B

    2006-04-01

    A single-event microkinetic model for the catalytic hydroconversion of hydrocarbons on Pt/H-US-Y bifunctional zeolite catalysts developed for low-pressure vapor phase conditions was extended to cover high-pressure vapor phase and liquid phase conditions. The effect of the density of the bulk hydrocarbon phase on the physisorption as well as on the protonation steps of the reaction network was accounted for explicitly and can be interpreted in terms of "compression" of the hydrocarbon sorbate inside the zeolite pores and "solvation" of the catalyst framework by the dense bulk hydrocarbon phase. The bulk phase density effect on the physisorbed state is described via a single excess free enthalpy of physisorption. A dense bulk hydrocarbon phase destabilizes the sorbate molecules inside the catalyst pores. An expression of the excess free enthalpy of physisorption involving the fugacity coefficient and a zeolite dependent factor allows description of physisorption data. Typical excess free enthalpy values are in the range 1.5-5.1 kJ mol(-1) increasing with carbon number in the series of C5-C16 alkanes. At high-pressure vapor phase and liquid phase conditions, the excess standard protonation enthalpy is estimated at -7.8 kJ mol(-1) leading to relatively more stable carbenium ions at dense bulk phase conditions. As a result of the excess physisorption and protonation properties, the lightest hydrocarbons in mixtures are more competitive at dense phase conditions and their conversion is enhanced compared to low-density conditions. PMID:16570981

  10. Possible room temperature superconductivity in conductors obtained by bringing alkanes into contact with a graphite surface

    NASA Astrophysics Data System (ADS)

    Kawashima, Yasushi

    2013-05-01

    Electrical resistances of conductors obtained by bringing alkanes into contact with a graphite surface have been investigated at room temperatures. Ring current in a ring-shaped container into which n-octane-soaked thin graphite flakes were compressed did not decay for 50 days at room temperature. After two HOPG plates were immersed into n-heptane and n-octane at room temperature, changes in resistances of the two samples were measured by four terminal technique. The measurement showed that the resistances of these samples decrease to less than the smallest resistance that can be measured with a high resolution digital voltmeter (0.1?V). The observation of persistent currents in the ring-shaped container suggests that the HOPG plates immersed in n-heptane and n-octane really entered zero-resistance state at room temperature. These results suggest that room temperature superconductor may be obtained by bringing alkanes into contact with a graphite surface.

  11. Fossil Leaves and Fossil Leaf n-Alkanes: Reconstructing the First Closed Canopied Rainforests

    NASA Astrophysics Data System (ADS)

    Graham, H. V.; Freeman, K. H.

    2013-12-01

    Although the age and location is disputed, the rise of the first closed-canopy forest is likely linked with the expansion of angiosperms in the late Cretacous or early Cenozoic. The carbon isotope 'canopy effect' reflects the extent of canopy closure, and is well documented in ?13C values of the leaves and leaf lipids in modern forests. To test the extent of canopy closure among the oldest documented angiosperm tropical forests, we analyzed isotopic characteristics of leaf fossils and leaf waxes from the Guaduas and Cerrejn Formations. The Guaduas Fm. (Maastrichtian) contains some of the earliest angiosperm fossils in the Neotropics, and both leaf morphology and pollen records at this site suggest an open-canopy structure. The Cerrejn Fm. (Paleocene) contains what are believed to be the first recorded fossil leaves from a closed-canopy forest. We analyzed the bulk carbon isotope content (?13Cleaf) of 199 fossil leaves, as well as the n-alkane concentration and chain-length distribution, and ?13C of alkanes (?13Clipid) of 73 fossil leaves and adjacent sediment samples. Fossil leaves are dominated by eudicots and include ten modern plant families (Apocynaceae, Bombaceae, Euphorbaceae, Fabaceae, Lauraceae, Malvaceae, Meliaceae, Menispermaceae, Moraceae, Sapotaceae). We interpreted extent of canopy coverage based on the range of ?13Cleaf values. The narrow range of ?13C values in leaves from the Guaduas Fm (2.7) is consistent with an open canopy. A significantly wider range in values (6.3) suggests a closed-canopy signature for site 0315 of the Cerrejn Fm,. In contrast, at Site 0318, a lacustrine deposit, leaves had a narrow range (3.3) in ?13C values, and this is not consistent with a closed-canopy, but is consistent with leaf assemblages from a forest edge. Leaves that accumulate in lake sediments tend to be biased toward plants living at the lake edge, which do not experience closed-canopy conditions, and do not express the isotopic characteristics associated with canopy effect. A biomass flux-weighted model of alkane chain-length distribution and ?13Cleaf indicate n-alkanes extracted from bulk rock are consistent with inputs integrated over time from plants represented by fossil leaves. In a modern rainforest, we found leaf lipid amounts markedly higher in the shaded and moist understory, consistent with studies that show alkanes proffer fungal protection. Shade tolerance is associated with higher plant orders and, consistent with this, literature data for modern plants from 30 plant orders shows alkane production in asterids and rosids is 2 to 3 times greater than in basal angiosperms or gymnosperms. The lower clades tend to contain greater amounts of terpenoids and novel benzylisoquinoline alkaloids, rather than alkanes. For our three fossil floras, alkane abundance is strongly influenced by depositional setting, with preservation best in the lacustrine setting. Within each site, abundance patterns are potentially influenced by both taxonomic affiliation and by canopy structure as measured by ?13Cleaf values, and such relationships shed light on the combined influences of plant evolution, canopy structure and the function of biochemical resources on the geochemical record of the first rainforests.

  12. Crossed-beam DC slice imaging of fluorine atom reactions with linear alkanes.

    PubMed

    Shi, Yuanyuan; Kamasah, Alexander; Joalland, Baptiste; Suits, Arthur G

    2015-05-14

    We report the reaction dynamics of F atom with selected alkanes studied by crossed beam scattering with DC slice ion imaging. The target alkanes are propane, n-butane, and n-pentane. The product alkyl radicals are probed by 157 nm single photon ionization following reaction at a collision energy of ?10 kcal mol(-1). The analyzed data are compared with the corresponding theoretical studies. Reduced translational energy distributions for each system show similar trends with little of the reaction exoergicity appearing in translation. However, the pentane reaction shows a somewhat smaller fraction of available energy in translation than the other two, suggesting greater energy channeled into pentyl internal degrees of freedom. The center-of-mass angular distributions all show backscattering as well as sharp forward scattering that decreases in relative intensity with the size of the molecule. Possible reasons for these trends are discussed. PMID:25978893

  13. Crossed-beam DC slice imaging of fluorine atom reactions with linear alkanes

    NASA Astrophysics Data System (ADS)

    Shi, Yuanyuan; Kamasah, Alexander; Joalland, Baptiste; Suits, Arthur G.

    2015-05-01

    We report the reaction dynamics of F atom with selected alkanes studied by crossed beam scattering with DC slice ion imaging. The target alkanes are propane, n-butane, and n-pentane. The product alkyl radicals are probed by 157 nm single photon ionization following reaction at a collision energy of 10 kcal mol-1. The analyzed data are compared with the corresponding theoretical studies. Reduced translational energy distributions for each system show similar trends with little of the reaction exoergicity appearing in translation. However, the pentane reaction shows a somewhat smaller fraction of available energy in translation than the other two, suggesting greater energy channeled into pentyl internal degrees of freedom. The center-of-mass angular distributions all show backscattering as well as sharp forward scattering that decreases in relative intensity with the size of the molecule. Possible reasons for these trends are discussed.

  14. Plasmid-determined alcohol dehydrogenase activity in alkane-utilizing strains of Pseudomonas putida.

    PubMed Central

    Benson, S; Shapiro, J

    1976-01-01

    We have identified an alcohol dehydrogenase activity in Pseudomonas putida strains carrying the CAM-OCT degradative plasmid that were grown on octane. The activity is nicotinamide adenine dinucleotide independent, sediments at 48,000 x g, and shows 20-fold greater activity with octanol rather than butanol as substrate. The enzyme is inducible by unoxidized alkane and is present only in strains that have the OCT plasmid genes for alkane degradation with a wild-type alcO locus. No analogous chromosomal dehydrogenase could be detected. Wild-type and actanol-negative mutants (alcA-) without plasmids both contain a constitutive nicotinamide adenine dinucleotide-linked soluble alcohol dehydrogenase activity. This means that alcA- mutants are cryptic for octanol oxidation and suggests that the particulate plasmid-coded alcohol dehydrogenase activity is active on surface- or membrane-bound substrate. PMID:177405

  15. Possible room temperature superconductivity in conductors obtained by bringing alkanes into contact with a graphite surface

    PubMed Central

    Kawashima, Yasushi

    2013-01-01

    Electrical resistances of conductors obtained by bringing alkanes into contact with a graphite surface have been investigated at room temperatures. Ring current in a ring-shaped container into which n-octane-soaked thin graphite flakes were compressed did not decay for 50 days at room temperature. After two HOPG plates were immersed into n-heptane and n-octane at room temperature, changes in resistances of the two samples were measured by four terminal technique. The measurement showed that the resistances of these samples decrease to less than the smallest resistance that can be measured with a high resolution digital voltmeter (0.1?V). The observation of persistent currents in the ring-shaped container suggests that the HOPG plates immersed in n-heptane and n-octane really entered zero-resistance state at room temperature. These results suggest that room temperature superconductor may be obtained by bringing alkanes into contact with a graphite surface. PMID:23826513

  16. Leaf n-alkanes as characters differentiating coastal and continental Juniperus deltoides populations from the Balkan Peninsula.

    PubMed

    Raj?evi?, Nemanja; Jana?kovi?, Pedja; Dodo, Tanja; Teevi?, Vele; Bojovi?, Srdjan; Marin, Petar D

    2014-07-01

    The composition of the cuticular n-alkanes isolated from the leaves of nine populations of Juniperus deltoides R.P.Adams from continental and coastal areas of the Balkan Peninsula was characterized by GC-FID and GC/MS analyses. In the leaf waxes, 14 n-alkane homologues with chain-lengths ranging from C22 to C35 were identified. n-Tritriacontane (C33 ) was dominant in the waxes of all populations, but variations between the populations in the contents of all n-alkanes were observed. Several statistical methods (ANOVA, principal component, discriminant, and cluster analyses) were used to investigate the diversity and variability of the cuticular-leaf-n-alkane patterns of the nine J. deltoides populations. This is the first report on the n-alkane composition for this species. The multivariate statistical analyses evidenced a high correlation of the leaf-n-alkane pattern with the geographical distribution of the investigated samples, differentiating the coastal from the continental populations of this taxon. PMID:25044590

  17. Conversational scene analysis

    E-print Network

    Basu, Sumit

    2002-01-01

    In this thesis, we develop computational tools for analyzing conversations based on nonverbal auditory cues. We develop a notion of conversations as being made up of a variety of scenes: in each scene, either one speaker ...

  18. Macrocyclic alkanes in crude oils from the algaenan of Botryococcus braunii

    Microsoft Academic Search

    Michiele Audino; Kliti Grice; Robert Alexander; Robert I. Kagi

    2002-01-01

    New classes of biomarkers, macrocyclic alkanes, have been previously identified in high grade oil shales (torbanites, Late Carboniferous-Late Permian) containing remains of the freshwater alga Botryococcus braunii (B. braunii). In this study we report the occurrence of these compounds in two Indonesian crude oils (Minas and Duri, Tertiary) utilising metastable reaction monitoring GCMS experiments. Based on ?13C data and the

  19. Glucosinolate degradation products, alkanes and fatty acids from plants and cell cultures of Descurainia sophia.

    PubMed

    Afsharypuor, S; Lockwood, G B

    1985-12-01

    Allyl and 3-butenyl isothiocyanate with two nitriles and an epithiobutane derivative were estimated. These glucosinolate degradation products were found in callus, seed, and dried plant but not in suspension cultures. Seventeen alkanes and five fatty acids were also identified and estimated in plant material and cultures. 4-Methylthiobutyl and 2-phenylethyl isothiocyanates were also detected in seeds. Incubation of cultures at 4 increased levels of the fatty acids but not isothiocyanates. PMID:24254078

  20. Phase equilibria calculations with a modified SAFT equation of state. 1: Pure alkanes, alkanols, and water

    Microsoft Academic Search

    Thomas Kraska; Keith E. Gubbins

    1996-01-01

    The phase equilibria of the n-alkanes and the 1-alkanols have been calculated with the Lennard-Jones-SAFT equation of state of Mueller and Gubbins. This equation includes contributions from a dipole-dipole term, a modified association term, a chain term, and a Lennard-Jones term to account for monomer dispersion and overlap interactions. The influence of electrostatic forces due to the dipole moment has

  1. (Liquid + liquid) equilibrium for binary systems of N-formylmorpholine with alkanes

    Microsoft Academic Search

    Zhengrong Wang; Shuqian Xia; Peisheng Ma; Tao Liu; Kewei Han

    (Liquid+liquid) equilibrium (LLE) data were determined for four binary systems containing N-formylmorpholine (NFM) and alkanes (3-methylpentane, heptane, nonane, and 2,2,4-trimethylpentane) over the temperature range from around 300K to near 420K using a set of newly designed equilibrium equipment. The compositions of both light and heavy phases were analyzed by gas chromatography. The mutual solubility increased as the temperature increased for

  2. Activity coefficients at infinite dilution of alkanes and alkenes in 1-alkyl-3-methylimidazolium tetrafluoroborate

    Microsoft Academic Search

    Matthias Bahlmann; Silke Nebig; Jrgen Gmehling

    2009-01-01

    For the measurement of limiting activity coefficients different techniques are available. In this work the activity coefficients at infinite dilution ?i? of alkanes and alkenes in the ionic liquids 1-butyl-3-methylimidazolium tetrafluoroborate [BMIM]+[BF4]? and 1-hexyl-3-methylimidazolium tetrafluoroborate [HMIM]+[BF4]? from 303.15K to 353.15K were measured with the help of the dilutor technique. The new data were compared with already published experimental data measured

  3. Correlation of high-pressure diffusion and viscosity coefficients for n -alkanes

    Microsoft Academic Search

    J. H. Dymond; M. A. Awan

    1989-01-01

    Self-diffusion coefficient and viscosity coefficient data for liquid n-alkanes over the whole pressure range at different temperatures are satisfactorily correlated simultaneously by a method which is just an extension of that previously used to apply the smooth hard-sphere theory of transport properties to individual transport coefficients. Universal curves are developed for reduced quantities D* and ?* as a function of

  4. Isolation and characterization of a sulfate-reducing bacterium that anaerobically degrades alkanes.

    PubMed

    So, C M; Young, L Y

    1999-07-01

    An alkane-degrading, sulfate-reducing bacterial strain, AK-01, was isolated from an estuarine sediment with a history of chronic petroleum contamination. The bacterium is a short, nonmotile, non-spore-forming, gram-negative rod. It is mesophilic and grows optimally at pH 6.9 to 7.0 and at an NaCl concentration of 1%. Formate, fatty acids (C4 to C16) and hydrogen were readily utilized as electron donors. Sulfate, sulfite, and thiosulfate were used as electron acceptors, but sulfur, nitrite, and nitrate were not. Phenotypic characterization and phylogenetic analysis based on 16S rRNA gene sequence indicate that AK-01 is most closely related to the genera Desulfosarcina, Desulfonema, and Desulfococcus in the delta subdivision of the class Proteobacteria. It is phenotypically and phylogenetically different from strains Hxd3 and TD3, two previously reported isolates of alkane-degrading, sulfate-reducing bacteria. The alkanes tested to support growth of AK-01 had chain lengths of C13 to C18. 1-Alkenes (C15 and C16) and 1-alkanols (C15 and C16) also supported growth. The doubling time for growth on hexadecane was 3 days, about four times longer than that for growth on hexadecanoate. Mineralization of hexadecane was indicated by the recovery of 14CO2 from cultures grown on [1-14C]hexadecane. Degradation of hexadecane was dependent on sulfate reduction. The stoichiometric ratio (as moles of sulfate reduced per mole of hexadecane degraded) was 10.6, which is very close to the theoretical ratio of 12.25, assuming a complete oxidation to CO2. Anaerobic alkane degradation by sulfate reducers may be a more widespread phenomenon than was previously thought. PMID:10388691

  5. Enthalpies of dissolution of n-alkanes in a mixture of methanol-formamide

    NASA Astrophysics Data System (ADS)

    Batov, D. V.; Kustov, A. V.; Antonova, O. A.; Smirnova, N. L.

    2015-06-01

    The enthalpies of dissolution of n-hexane, n-octane, and n-decane are determined thermochemically under standard conditions to describe nonspecific solvation in a mixed solvent of methanol-formamide. Experimental data are matched with the values obtained using model calculations. It is found that the differences between the experimental and calculated enthalpies of dissolution in the region with a high content of formamide could be due to the preferable solvation of n-alkanes by methanol.

  6. Azulene Chemistry

    NSDL National Science Digital Library

    The month's featured molecules come from the paper An Azulene-Based Discovery Experiment: Challenging Students To Watch for the "False Assumption" by Charles Garner illustrating some of the chemistry of a substituted azulene. Azulene is a structural isomer of naphthalene and differs from it in several important ways, the most obvious being azulene's intense blue color, which arises from the S0 ? S2 transition. Another unusual feature of this molecule is that its fluorescence arises from the reverse of this transition rather than from S1 ? S0.

  7. Interstellar chemistry

    PubMed Central

    Klemperer, William

    2006-01-01

    In the past half century, radioastronomy has changed our perception and understanding of the universe. In this issue of PNAS, the molecular chemistry directly observed within the galaxy is discussed. For the most part, the description of the molecular transformations requires specific kinetic schemes rather than chemical thermodynamics. Ionization of the very abundant molecular hydrogen and atomic helium followed by their secondary reactions is discussed. The rich variety of organic species observed is a challenge for complete understanding. The role and nature of reactions involving grain surfaces as well as new spectroscopic observations of interstellar and circumstellar regions are topics presented in this special feature. PMID:16894148

  8. Chemistry References

    NSDL National Science Digital Library

    Kim

    2007-08-08

    This site highlights chemistry resources that we consider essentiala fabulous periodic table, a database of chemical compounds, a set of demonstrations of chemical reactions that are just plain spectacular, and, dont forget, laboratory safety. Articles from the web sites Whats That Stuff? and Science News for Kids can be used as supplemental reading all through the year. This site explains the history and characteristics of over 20 substances, such as sunscreen, Cheese Whiz, baseballs, fluoride, new car smell, ink, lipstick, bug spray, and licorice. The individual articles are nontechnical for the most part and are presented in a fun way that readers will enjoy. Also, if a ...

  9. Alkanes adsorbed on carbon nanotubes: specific surface areas and isothermal adsorption kinetics

    NASA Astrophysics Data System (ADS)

    Rawat, Dinesh; Furuhashi, Toyohisa; Migone, Aldo; Ramirez-Pastor, Jose Antonio; Roma, Federico; Riccardo, Jose Luis

    2009-03-01

    We measured the specific surface area of single-wall carbon nanotube substrates using methane, ethane, propane and butane adsorption isotherms. The monolayer capacity for each gas was obtained from the BET equation. We found that the specific surface areas measured decrease as the length of the alkanes used to measure them increases. This trend may be explained by the fact that an increasing fraction of the substrate's surface should be left uncovered as longer adsorbates are used. We also studied the isothermal adsorption kinetics of these alkanes. We monitored the evolution of the gas pressure with time, from the instant at which the gas is added to the sample cell up until the time at which equilibrium is reached. Equilibration times for comparable fractional coverages increase with increasing alkane length. While the equilibration times decrease with increasing fractional coverage for methane and ethane, they increase with increasing coverage for propane and butane (this increase may be due to reorientation of the adsorbed molecules in the film).

  10. Compositional Characteristics and Geochemical Significance of N-alkanes in Process of Crude Oil Cracking

    NASA Astrophysics Data System (ADS)

    Tang, Xiaoqiang; Huang, Guanghui; Zhang, Min; Han, Jinping

    The simulation experiments with crude oil samples have been performed in laboratory by using high temperature simulative techniques, and the characteristics of change of compositions have also been analyzed by gcochemical methods in the cracking process. The results indicate that before a large number of gaseous hydrocarbons being generated by cracking of crude oil, the n-alkanes of high molecular weight from crude oil has already begun to be pyrolyzed, and C +15 hydrocarbon mainly cracked into C 6-C 14. With increasing maturity, C 6-C 14 is further transformed into C 1-C 5, accompanied by the output of benzene, ultimately forming methane and cracking bitumen. In the pyrolysis of n-alkanes process, abundance of benzene and its homologue show significantly increasing, which can be used as potential distinguishing marks of crude oil cracking. Besides, comparative simulation experiments on n-hexadecane have been performed in laboratory by the same experimental condition, and it shows that the characteristics of change of compositions are basically the same as that of n-alkanes in crude oil.

  11. Assessing carbon and hydrogen isotopic fractionation of diesel fuel n-alkanes during progressive evaporation.

    PubMed

    Muhammad, Syahidah A; Hayman, Alan R; Van Hale, Robert; Frew, Russell D

    2015-01-01

    Compound-specific isotope analysis offers potential for fingerprinting of diesel fuels, however, possible confounding effects of isotopic fractionation due to evaporation need to be assessed. This study measured the fractionation of the stable carbon and hydrogen isotopes in n-alkane compounds in neat diesel fuel during evaporation. Isotope ratios were measured using a continuous flow gas chromatograph/isotope ratio mass spectrometer. Diesel samples were progressively evaporated at 24 2C for 21 days. Increasing depletion of deuterium in nC12-nC17 alkanes in the remaining liquid with increasing carbon chain length was observed. Negligible carbon isotope fractionation was observed. Preferential vaporization was measured for the shorter chain n-alkanes and the trend decreased with increasing chain length. The decrease in ?(2) H values indicates the preferential vaporization of the isotopically heavier species consistent with available quantitative data for hydrocarbons. These results are most important in the application of stable isotope technology to forensic analysis of diesel. PMID:25131396

  12. Diffusion of Trace Alkanes in Polyethylene: Spin-Echo Measurements and Monte-Carlo Simulations

    NASA Astrophysics Data System (ADS)

    von Meerwall, E.; Lin, H.; Mattice, W. L.

    2006-03-01

    We have performed pulsed-gradient NMR diffusion (D) measurements on five n-alkanes (24, 28, 36, 44, and 60 carbons) in a polyethylene (PE) host (M = 33 kDa) as function of concentration c (2-10 wt.%) at 180 deg. C. Monte-Carlo simulations on the second-nearest-neighbor diamond lattice (38, 46, 62, and 78 carbons) at c between 2 and 15 wt.% in a host of PE (M = 4.5 kDa) explored static and dynamic properties. The bridging method uses beads combining adjacent moieties and incorporates two-bead moves; it permits detailed reconstruction of the chain molecules at any stage. It uses discretized short-range rotational isomeric state and long-range intra- and interchain Lennard-Jones potentials. For both experiment and simulation, trace D was obtained by extrapolating D(c) to c = 0 using the Fujita-Doolittle equation with known chain-end free-volume parameters. A ratio of 330 Monte-Carlo steps per picosecond brings simulation into congruence with experiment; this factor is identical to that required for PE melts. The applicability of the Rouse model is approached only for the largest alkanes, but the M(alkane)-dependence of trace D is seen to be in transition from the Rouse-like 1/M-scaling to a steeper value characteristic of reptation with constraint release.

  13. Diffusion coefficients in CO2/n-alkane binary liquid mixtures by molecular simulation.

    PubMed

    Zabala, Damelys; Nieto-Draghi, Carlos; de Hemptinne, Jean Charles; Lpez de Ramos, Aura L

    2008-12-25

    The objective of this work was to determine Fick diffusion coefficients in CO2/n-alkane binary mixtures without experimental test. For doing so, Maxwell-Stefan (MS) diffusivity was calculated by molecular simulation. Simultaneously, a thermodynamic factor was estimated using the PC-SAFT (perturbed chain statistical associating fluid theory) equation of state (eos). The binary Fick diffusivities are calculated as the product of both quantities. The binary mixtures investigated contain CO2 and various n-alkanes (nC10, nC16, nC22, nC28, nC44), at their bubble pressure at varying temperatures between 298 and 373 K. The calculated values of Fick diffusivities were compared against the experimental ones for the systems where literature data exist. An average deviation of 26% was found for the CO2/n-decane and 15% for CO2/n-hexadecane mixtures. These results support that molecular simulation can be employed as a tool for the determination of Fick diffusivities in high pressure systems, like in oil reservoirs, without the need to construct a complicated and expensive experimental setup. This method only requires the phase behavior of the desired system, and it can be used for multicomponent mixtures. As an example, predictions of Fick diffusivities were done for CO2 binary mixtures with heavy n-alkanes (nC22, nC28, nC44). PMID:19367942

  14. Direct Conversion of Energy.

    ERIC Educational Resources Information Center

    Corliss, William R.

    This publication is one of a series of information booklets for the general public published by the United States Atomic Energy Commission. Direct energy conversion involves energy transformation without moving parts. The concepts of direct and dynamic energy conversion plus the laws governing energy conversion are investigated. Among the topics

  15. Microbial Oxidation of Gaseous Hydrocarbons: Production of Secondary Alcohols from Corresponding n-Alkanes by Methane-Utilizing Bacteria

    PubMed Central

    Patel, Ramesh N.; Hou, C. T.; Laskin, A. I.; Felix, A.; Derelanko, P.

    1980-01-01

    Over 20 new strains of methane-utilizing bacteria were isolated from lake water and soil samples. Cell suspensions of these and of other known strains of methane-utilizing bacteria oxidized n-alkanes (propane, butane, pentane, hexane) to their corresponding secondary alcohols (2-propanol, 2-butanol, 2-pentanol, 2-hexanol). The product secondary alcohols accumulated extracellularly. The rate of production of secondary alcohols varied with the organism used for oxidation. The average rate of 2-propanol, 2-butanol, 2-pentanol, and 2-hexanol production was 1.5, 1.0, 0.15, and 0.08 ?mol/h per 5.0 mg of protein in cell suspensions, respectively. Secondary alcohols were slowly oxidized further to the corresponding methylketones. Primary alcohols and aldehydes were also detected in low amounts (rate of production were 0.05 to 0.08 ?mol/h per 5.0 mg of protein in cell suspensions) as products of n-alkane (propane and butane) oxidation. However, primary alcohols and aldehydes were rapidly metabolized further by cell suspensions. Methanol-grown cells of methane-utilizing bacteria did not oxidize n-alkanes to their corresponding secondary alcohols, indicating that the enzymatic system required for oxidation of n-alkanes was induced only during growth on methane. The optimal conditions for in vivo secondary alcohol formation from n-alkanes were investigated in Methylosinus sp. (CRL-15). The rate of 2-propanol and 2-butanol production was linear for the 40-min incubation period and increased directly with cell protein concentration up to 12 mg/ml. The optimal temperature and pH for the production of 2-propanol and 2-butanol were 40C and pH 7.0. Metalchelating agents inhibited the production of secondary alcohols. The activities for the hydroxylation of n-alkanes in various methylotrophic bacteria were localized in the cell-free particulate fractions precipitated by centrifugation between 10,000 and 40,000 g. Both oxygen and reduced nicotinamide adenine dinucleotide were required for hydroxylation activity. The metal-chelating agents inhibited hydroxylation of n-alkanes by the particulate fraction, indicating the involvement of a metal-containing enzyme system in the oxidation of n-alkanes. The production of 2-propanol from the corresponding n-alkane by the particulate fraction was inhibited in the presence of methane, suggesting that the subterminal hydroxylation of n-alkanes may be catalyzed by methane monooxygenase. PMID:16345537

  16. Chemistry of the outer planets

    NASA Technical Reports Server (NTRS)

    Scattergood, Thomas W.

    1992-01-01

    Various aspects were studied of past or present chemistry in the atmospheres of the outer planets and their satellites using lab simulations. Three areas were studied: (1) organic chemistry induced by kinetically hot hydrogen atoms in the region of Jupiter's atmosphere containing the ammonia cirrus clouds; (2) the conversion of NH3 into N2 by plasmas associated with entry of meteors and other objects into the atmosphere of early Titan; and (3) the synthesis of simple hydrocarbons and HCN by lightning in mixtures containing N2, CH4, and NH3 representing the atmospheres of Titan and the outer planets. The results showed that: (1) hot H2 atoms formed from the photodissociation of NH3 in Jupiter's atmosphere could account for some of the atmospheric chemistry in the ammonia cirrus cloud region; (2) the thermalization of hot H2 atoms in atmospheres predominated by molecular H is not as rapid as predicted by elastic collision theory; (3) the net quantum loss of NH3 in the presence of a 200 fold excess of H2 is 0.02, much higher than was expected from the amount of H2 present; (4) the conversion of NH3 into N2 in plasmas associated with infalling meteors is very efficient and rapid, and could account for most of the N2 present on Titan; (5) the yields of C2H2 and HCN from lightning induced chemistry in mixtures of CH4 and N2 is consistent with quenched thermodynamic models of the discharge core; and (6) photolysis induced by the UV light emitted by the gases in the hot plasmas may account for some, if not most, of the excess production of C2H6 and the more complex hydrocarbons.

  17. Syllabus Chemistry 1225

    E-print Network

    Simons, Jack

    Syllabus Chemistry 1225 Summer 2013 Instructor: David Thomas: You must obtain a copy of the Chemistry 1225 lab manual Experiments in General Chemistry Featuring MeasureNet from the University Bookstore, 2nd

  18. Computational Chemistry List

    NSDL National Science Digital Library

    The Computational Chemistry List (CCL) was established as an independent electronic forum for chemistry researchers and educators from around the world. The discussions cover all aspects of computational chemistry.

  19. Science Update: Inorganic Chemistry

    ERIC Educational Resources Information Center

    Rawls, Rebecca

    1978-01-01

    This first in a series of articles describing the state of the art of various branches of chemistry reviews inorganic chemistry, including bioinorganic, photochemistry, organometallic, and solid state chemistries. (SL)

  20. Relumped single-event microkinetic model for alkane hydrocracking on shape-selective catalysts: catalysis on ZSM-22 pore mouths, bridge acid sites and micropores

    Microsoft Academic Search

    C. S. Laxmi Narasimhan; J. W. Thybaut; G. B. Marin; J. F. Denayer; G. V. Baron; J. A. Martens; P. A. Jacobs

    2004-01-01

    A relumped single-event microkinetic (SEMK) model is developed to describe alkane hydroconversion on shape-selective Pt-H\\/ZSM-22. The model, considers n-alkane, mono-, di- and tri-branched alkanes for each carbon number and is developed according to the reaction rules formulated for the molecular SEMK model on ZSM-22. Differences in physisorption and protonation behaviour among the carbenium ions on ZSM-22 are accounted for. Reactions

  1. Optimisation of the dynamical behaviour of the anisotropic united atom model of branched alkanes: application to the molecular simulation of fuel gasoline

    Microsoft Academic Search

    Carlos Nieto-Draghi; Anthony Bocahut; Benot Creton; Pascal Have; Aziz Ghoufi; Aurlie Wender; Anne Boutin; Bernard Rousseau; Laurent Normand

    2008-01-01

    In the present work, we have optimised the dynamical behaviour of the anisotropic united atom (AUA) intermolecular potential for branched alkanes developed by Bourasseau et al. [E. Bourasseau, P. Ungerer, A. Boutin, and A.H. Fuchs, Monte Carlo simulation of branched alkanes and long chain n-alkanes with anisotropic united atoms intermolecular potential, Mol. Sim. 28 (2002), pp. 317336], by a modification

  2. Reflections on Doctoral Education in Chemistry. Carnegie Essays on the Doctorate: Chemistry.

    ERIC Educational Resources Information Center

    Kwiram, Alvin L.

    The Carnegie Foundation commissioned a collection of essays as part of the Carnegie Initiative on the Doctorate (CID). Essays and essayists represent six disciplines that are part of the CID: chemistry, education, English, history, mathematics, and neuroscience. Intended to engender conversation about the conceptual foundation of doctoral

  3. Anaerolineaceae and Methanosaeta turned to be the dominant microorganisms in alkanes-dependent methanogenic culture after long-term of incubation.

    PubMed

    Liang, Bo; Wang, Li-Ying; Mbadinga, Serge Maurice; Liu, Jin-Feng; Yang, Shi-Zhong; Gu, Ji-Dong; Mu, Bo-Zhong

    2015-12-01

    The methanogenic alkanes-degrading enrichment culture which had been incubated for over 1,300days amended with n-alkanes (C15-C20) was investigated through clone libraries of bacteria, archaea and assA, mcrA functional genes. These enrichment cultures were obtained from oily sludge after an initial incubation of the oily sludge without any carbon source and then an enrichment transfer with n-alkanes (C15-C20) for acclimation. Activation of alkanes, methane precursor generation and methanogenic pathways are considered as three pivotal stages for the continuous methanogenesis from degradation of alkanes. The presence of functional genes encoding the alkylsuccinate synthase ?-subunit indicated that fumarate addition is most likely the one of initial activation step for degradation of n-alkanes. Degradation intermediates of n-alkanes were octadecanoate, hexadecanoate, butyrate, isobutyrate, acetate and propionate, which could provide the appropriate substrates for acetate formation. Both methyl coenzyme M reductase gene and 16S rRNA gene analysis showed that microorganisms of Methanoseata were the most dominant methanogens, capable of using acetate as the electron donor to produce methane. Bacterial clone libraries showed organisms of Anaerolineaceae (within the phylum of Chloroflexi) were predominant (45.5%), indicating syntrophically cooperation with Methanosaeta archaea was likely involved in the process of methanogenic degradation of alkanes. Alkanes may initially be activated via fumarate addition and degraded to fatty acids, then converted to acetate, which was further converted to methane and carbon dioxide by methanogens. PMID:26080793

  4. Phase equilibria calculations with a modified SAFT equation of state. 2: Binary mixtures of n-alkanes, 1-alkanols, and water

    SciTech Connect

    Kraska, T.; Gubbins, K.E. [Cornell Univ., Ithaca, NY (United States). School of Chemical Engineering] [Cornell Univ., Ithaca, NY (United States). School of Chemical Engineering

    1996-12-01

    The Lennard-Jones-statistical association fluid theory (LJ-SAFT) is applied to binary mixtures containing one self-associating and one nonassociating substance. The binary systems studied here are n-alkane/n-alkane, 1-alkanol/n-alkane, and water/n-alkane mixtures. For cases where the dipole-dipole term is needed, the influence of induction is also investigated. The results with LJ-SAFT exhibit better agreement with experimental data than SAFT. This improvement is due to the exchange of the hard-sphere reference system by the LJ reference system.

  5. Science Update: Inorganic Chemistry.

    ERIC Educational Resources Information Center

    Rawls, Rebecca

    1981-01-01

    Describes areas of inorganic chemistry which have changed dramatically in the past year or two, including photochemistry, electrochemistry, organometallic complexes, inorganic reaction theory, and solid state chemistry. (DS)

  6. Chemistry Bachelor of Science in Chemistry 4 YEAR TYPICAL

    E-print Network

    Carter, John

    Chemistry Bachelor of Science in Chemistry 4 YEAR TYPICAL PROGRAM OF STUDY 2013-2014 DEGREE OF SCIENCE & ENGINEERING Department of Chemistry | Office: Bannan 516 chemistry@seattleu.edu | www.seattleu.edu/scieng/chemistry

  7. Clay minerals and metal oxides strongly influence the structure of alkane-degrading microbial communities during soil maturation.

    PubMed

    Steinbach, Annelie; Schulz, Stefanie; Giebler, Julia; Schulz, Stephan; Pronk, Geertje J; Kgel-Knabner, Ingrid; Harms, Hauke; Wick, Lukas Y; Schloter, Michael

    2015-07-01

    Clay minerals, charcoal and metal oxides are essential parts of the soil matrix and strongly influence the formation of biogeochemical interfaces in soil. We investigated the role of these parental materials for the development of functional microbial guilds using the example of alkane-degrading bacteria harbouring the alkane monooxygenase gene (alkB) in artificial mixtures composed of different minerals and charcoal, sterile manure and a microbial inoculum extracted from an agricultural soil. We followed changes in abundance and community structure of alkane-degrading microbial communities after 3 and 12 months of soil maturation and in response to a subsequent 2-week plant litter addition. During maturation we observed an overall increasing divergence in community composition. The impact of metal oxides on alkane-degrading community structure increased during soil maturation, whereas the charcoal impact decreased from 3 to 12 months. Among the clay minerals illite influenced the community structure of alkB-harbouring bacteria significantly, but not montmorillonite. The litter application induced strong community shifts in soils, maturated for 12 months, towards functional guilds typical for younger maturation stages pointing to a resilience of the alkane-degradation function potentially fostered by an extant 'seed bank'. PMID:25535940

  8. Effects of Surfactant Mixtures, Including Corexit 9527, on Bacterial Oxidation of Acetate and Alkanes in Crude Oil

    PubMed Central

    Bruheim, Per; Bredholt, Harald; Eimhjellen, Kjell

    1999-01-01

    Mixtures of nonionic and anionic surfactants, including Corexit 9527, were tested to determine their effects on bacterial oxidation of acetate and alkanes in crude oil by cells pregrown on these substrates. Corexit 9527 inhibited oxidation of the alkanes in crude oil by Acinetobacter calcoaceticus ATCC 31012, while Span 80, a Corexit 9527 constituent, markedly increased the oil oxidation rate. Another Corexit 9527 constituent, the negatively charged dioctyl sulfosuccinate (AOT), strongly reduced the oxidation rate. The combination of Span 80 and AOT increased the rate, but not as much as Span 80 alone increased it, which tentatively explained the negative effect of Corexit 9527. The results of acetate uptake and oxidation experiments indicated that the nonionic surfactants interacted with the acetate uptake system while the anionic surfactant interacted with the oxidation system of the bacteria. The overall effect of Corexit 9527 on alkane oxidation by A. calcoaceticus ATCC 31012 thus seems to be the sum of the independent effects of the individual surfactants in the surfactant mixture. When Rhodococcus sp. strain 094 was used, the alkane oxidation rate decreased to almost zero in the presence of a mixture of Tergitol 15-S-7 and AOT even though the Tergitol 15-S-7 surfactant increased the alkane oxidation rate and AOT did not affect it. This indicated that there was synergism between the two surfactants rather than an additive effect like that observed for A. calcoaceticus ATCC 31012. PMID:10103264

  9. Solar thermal conversion

    NASA Technical Reports Server (NTRS)

    Selcuk, M. K.

    1978-01-01

    A brief review of the fundamentals of the conversion of solar energy into mechanical work (or electricity via generators) is given. Both past and present work on several conversion concepts are discussed. Solar collectors, storage systems, energy transport, and various types of engines are examined. Ongoing work on novel concepts of collectors, energy storage and thermal energy conversion are outlined and projections for the future are described. Energy costs for various options are predicted and margins and limitations are discussed.

  10. Conversing with Computers

    NASA Technical Reports Server (NTRS)

    2004-01-01

    I/NET, Inc., is making the dream of natural human-computer conversation a practical reality. Through a combination of advanced artificial intelligence research and practical software design, I/NET has taken the complexity out of developing advanced, natural language interfaces. Conversational capabilities like pronoun resolution, anaphora and ellipsis processing, and dialog management that were once available only in the laboratory can now be brought to any application with any speech recognition system using I/NET s conversational engine middleware.

  11. Alkane degradation under anoxic conditions by a nitrate-reducing bacterium with possible involvement of the electron acceptor in substrate activation

    PubMed Central

    Zedelius, Johannes; Rabus, Ralf; Grundmann, Olav; Werner, Insa; Brodkorb, Danny; Schreiber, Frank; Ehrenreich, Petra; Behrends, Astrid; Wilkes, Heinz; Kube, Michael; Reinhardt, Richard; Widdel, Friedrich

    2011-01-01

    Microorganisms can degrade saturated hydrocarbons (alkanes) not only under oxic but also under anoxic conditions. Three denitrifying isolates (strains HxN1, OcN1, HdN1) able to grow under anoxic conditions by coupling alkane oxidation to CO2 with NO3? reduction to N2 were compared with respect to their alkane metabolism. Strains HxN1 and OcN1, which are both Betaproteobacteria, utilized n-alkanes from C6 to C8 and C8 to C12 respectively. Both activate alkanes anaerobically in a fumarate-dependent reaction yielding alkylsuccinates, as suggested by present and previous metabolite and gene analyses. However, strain HdN1 was unique in several respects. It belongs to the Gammaproteobacteria and was more versatile towards alkanes, utilizing the range from C6 to C30. Neither analysis of metabolites nor analysis of genes in the complete genome sequence of strain HdN1 hinted at fumarate-dependent alkane activation. Moreover, whereas strains HxN1 and OcN1 grew with alkanes and NO3?, NO2? or N2O added to the medium, strain HdN1 oxidized alkanes only with NO3? or NO2? but not with added N2O; but N2O was readily used for growth with long-chain alcohols or fatty acids. Results suggest that NO2? or a subsequently formed nitrogen compound other than N2O is needed for alkane activation in strain HdN1. From an energetic point of view, nitrogenoxygen species are generally rather strong oxidants. They may enable enzymatic mechanisms that are not possible under conditions of sulfate reduction or methanogenesis and thus allow a special mode of alkane activation. PMID:21837252

  12. CHEMISTRY IN EVAPORATING ICES-UNEXPLORED TERRITORY

    SciTech Connect

    Cecchi-Pestellini, Cesare [INAF-Osservatorio Astronomico di Cagliari, Strada n.54, Loc. Poggio dei Pini, 09012 Capoterra (Italy); Rawlings, Jonathan M. C.; Viti, Serena; Williams, David A., E-mail: ccp@ca.astro.i, E-mail: jcr@star.ucl.ac.u, E-mail: sv@star.ucl.ac.u, E-mail: daw@star.ucl.ac.u [Department of Physics and Astronomy, University College London, Gower Street, London WC1E 6BT (United Kingdom)

    2010-12-20

    We suggest that three-body chemistry may occur in warm high-density gas evaporating in transient co-desorption events on interstellar ices. Using a highly idealized computational model we explore the chemical conversion from simple species of the ice to more complex species containing several heavy atoms, as a function of density and of adopted three-body rate coefficients. We predict that there is a wide range of densities and rate coefficients in which a significant chemical conversion may occur. We discuss the implications of this idea for the astrochemistry of hot cores.

  13. Trace Chemistry

    NASA Technical Reports Server (NTRS)

    Radhakrishnan, Krishnan; Whitefield, Philip

    1999-01-01

    The goals of the trace chemistry group were to identify the processes relevant to aerosol and aerosol precursor formation occurring within aircraft gas turbine engines; that is, within the combustor, turbine, and nozzle. The topics of discussion focused on whether the chemistry of aerosol formation is homogeneous or heterogeneous; what species are important for aerosol and aerosol precursor formation; what modeling/theoretical activities to pursue; what experiments to carry out that both support modeling activities and elucidate fundamental processes; and the role of particulates in aerosol and aerosol precursor formation. The consensus of the group was that attention should be focused on SO2, SO3, and aerosols. Of immediate concern is the measurement of the concentration of the species SO3, SO2, H2SO4 OH, HO2, H2O2, O, NO, NO2, HONO, HNO3, CO, and CO2 and particulates in various engines, both those currently in use and those in development. The recommendation was that concentration measurements should be made at both the combustor exit and the engine exit. At each location the above species were classified into one of four categories of decreasing importance, Priority I through IV, as follows: Combustor exit: Priority I species - SO3:SO2 ratio, SO3, SO2, and particulates; Priority II species: OH and O; Priority III species - NO and NO2; and Priority IV species - CO and CO2. For the Engine exit: Priority I species - SO3:SO2 ratio, SO3, SO2,H2SO4, and particulates; Priority II species: OH,HO2, H2O2, and O; Priority III species - NO, NO2, HONO, and HNO3; and Priority IV species - CO and CO2. Table I summarizes the anticipated concentration range of each of these species. For particulate matter, the quantities of interest are the number density, size distribution, and composition. In order to provide data for validating multidimensional reacting flow models, it would be desirable to make 2-D, time-resolved measurements of the concentrations of the above species and, in addition, of the pressure, temperature, and velocity. A near term goal of the experimental program should be to confirm the nonlinear effects of sulfur speciation, and if present, to provide an explanation for them. It is also desirable to examine if the particulate matter retains any sulfur. The recommendation is to examine the effects on SOx production of variations in fuel-bound sulfur and aromatic content (which may affect the amount of particulates formed). These experiments should help us to understand if there is a coupling between particulate formation and SO, concentration. Similarly, any coupling with NOx can be examined either by introducing NOx into the combustion air or by using fuel-bound nitrogen. Also of immediate urgency is the need to establish and validate a detailed mechanism for sulfur oxidation/aerosol formation, whose chemistry is concluded to be homogeneous, because there is not enough surface area for heterogeneous effects. It is envisaged that this work will involve both experimental and theoretical programs. The experimental work will require, in addition to the measurements described above, fundamental studies in devices such as flow reactors and shock tubes. Complementing this effort should be modeling and theoretical activities. One impediment to the successful modeling of sulfur oxidation is the lack of reliable data for thermodynamic and transport properties for several species, such as aqueous nitric acid, sulfur oxides, and sulfuric acid. Quantum mechanical calculations are recommended as a convenient means of deriving values for these properties. Such calculations would also help establish rate constants for several important reactions for which experimental measurements are inherently fraught with uncertainty. Efforts to implement sufficiently detailed chemistry into computational fluid dynamic codes should be continued. Zero- and one-dimensional flow models are also useful vehicles for elucidating the minimal set of species and reactions that must be included in two- and three-dimensional modeling studies.

  14. Chemistry and Chemical Biology

    E-print Network

    Linhardt, Robert J.

    Chemistry and Chemical Biology AT RENSSELAER ONE WORD To Drive Discovery -- RENSSELAER What is the best Chemistry Ph.D. program for you? Choosing the right Ph.D. Chemistry program depends on many interests, we encourage you consider the Department of Chemistry and Chemical Biology at Rensselaer. WHY

  15. New covalent modifications of phosphatidylethanolamine by alkanals: mass spectrometry based structural characterization and biological effects

    PubMed Central

    Annibal, Andrea; Schubert, Kristin; Wagner, Ulf; Hoffmann, Ralf; Schiller, Jrgen; Fedorova, Maria

    2014-01-01

    The pathophysiology of numerous human disorders, such as atherosclerosis, diabetes, obesity and Alzheimer's disease, is accompanied by increased production of reactive oxygen species (ROS). ROS can oxidatively damage nearly all biomolecules, including lipids, proteins and nucleic acids. In particular, (poly)unsaturated fatty acids within the phospholipid (PL) structure are easily oxidized by ROS to lipid peroxidation products (LPP) carrying reactive carbonyl groups. Carbonylated LPP are characterized by high in vivo toxicity due to their reactivity with nucleophilic substrates (Lys-, Cys-and His-residues in proteins or amino groups of phosphatidylethanolamines [PE]). Adducts of unsaturated LPP with PE amino groups have been reported before, whereas less is known about the reactivity of saturated alkanals which are significantly increased in vivo under oxidative stress conditions towards nucleophilic groups of PLs. Here, we present a study of new alkanal-dipalmitoyl-phosphatidylethanolamine (DPPE) adducts by MS-based approaches, using consecutive fragmentation (MSn) and multiple reaction monitoring techniques. At least eight different DPPEhexanal adducts were identified, including Schiff base and amide adducts, six of which have not been reported before. The structures of these new compounds were determined by their fragmentation patterns using MSn experiments. The new PE-hexanal adducts contained dimeric and trimeric hexanal conjugates, including cyclic adducts. A new pyridine ring containing adduct of DPPE and hexanal was purified by HPLC, and its biological effects were investigated. Incubation of peripheral blood mononuclear cells and monocytes with modified DPPE did not result in increased production of TNF-? as one selected inflammation marker. However, incorporation of modified DPPE into 1,2-dipalmitoleoyl-sn-phosphatidylethanolamine multilamellar vesicles resulted in a negative shift of the transition temperature, indicating a possible role of alkanal-derived modifications in changes of membrane structure. 2014 The Authors. Journal of Mass Spectrometry published by John Wiley & Sons, Ltd. PMID:25044840

  16. ACS Green Chemistry Institute

    NSDL National Science Digital Library

    This special feature page from the American Chemical Society (ACS) showcases the up-and-coming field of "green chemistry," that is, the development of chemical products and processes that eliminate or reduce the use and generation of hazardous substances. A list of principles behind green chemistry, a searchable bibliography of green chemistry references, and green chemistry links (including conferences). This page comes from ACS's Green Chemistry Project, a three-year educational project to develop and disseminate green chemistry educational materials for graduate and undergraduate chemistry students.

  17. Oxygen Independent Alkane Formation by Non-Heme Iron-Dependent Cyanobacterial Aldehyde Decarbonylase: Investigation of Kinetics and Requirement for an External Electron Donor

    PubMed Central

    Eser, Bekir E.; Das, Debasis; Han, Jaehong; Jones, Patrik R.; Marsh, E. Neil G.

    2011-01-01

    Cyanobacterial aldehyde decarbonylase (cAD) is, structurally, a member of the di-iron carboxylate family of oxygenases. We previously reported that cAD from Prochlorococcus marinus catalyzes the unusual hydrolysis of aldehydes to produce alkanes and formate in a reaction that requires an external reducing system but does not require oxygen (Das et al., 2011, Angew. Chem. 50, 71487152). Here we demonstrate that cADs from divergent cyanobacterial classes, including the enzyme from N. puntiformes that was reported to be oxygen dependent, catalyze aldehyde decarbonylation at a much faster rate under anaerobic conditions, and that the oxygen in formate derives from water. The very low activity (< 1 turn-over/h) of cAD appears to result from inhibition by the ferredoxin reducing system used in the assay and the low solubility of the substrate. Replacing ferredoxin with the electron mediator phenazine methosulfate allowed the enzyme to function with various chemical reductants, with NADH giving the highest activity. NADH is not consumed during turn-over, in accord with the proposed catalytic role for the reducing system in the reaction. With octadecanal, a burst phase of product formation, kprod = 3.4 0.5 min?1 is observed indicating that chemistry is not rate-determining under the conditions of the assay. With the more soluble substrate, heptanal, kcat = 0.17 0.01 min?1 and no burst phase is observed, suggesting that a chemical step is limiting in the reaction of this substrate. PMID:22074177

  18. Brasilane sesquiterpenoids and alkane derivatives from cultures of the basidiomycete Coltricia sideroides.

    PubMed

    Hu, Dong-Bao; Zhang, Shen; He, Jiang-Bo; Dong, Ze-Jun; Li, Zheng-Hui; Feng, Tao; Liu, Ji-Kai

    2015-07-01

    Three new brasilane-type sesquiterpenoids, brasilanes A-C (1-3), together with two new alkane derivatives, colisiderin A (4) and 7(E),9(E)-undecandiene-2,4,5-triol (5), were isolated from cultures of the basidiomycete Coltricia sideroides. Their structures were elucidated by NMR and MS data analyses. The absolute configuration of 4 was determined by TDDFT ECD calculations while brasilane-type sesquiterpenoids were isolated from cultures of mushroom for the first time. Compounds 2 and 4 showed weak cytotoxicities against HL-60 and SW480, respectively. PMID:25987321

  19. Highly reactive nonheme iron(III) iodosylarene complexes in alkane hydroxylation and sulfoxidation reactions.

    PubMed

    Hong, Seungwoo; Wang, Bin; Seo, Mi Sook; Lee, Yong-Min; Kim, Myoung Jin; Kim, Hyung Rok; Ogura, Takashi; Garcia-Serres, Ricardo; Clmancey, Martin; Latour, Jean-Marc; Nam, Wonwoo

    2014-06-16

    High-spin iron(III) iodosylarene complexes bearing an N-methylated cyclam ligand are synthesized and characterized using various spectroscopic methods. The nonheme high-spin iron(III) iodosylarene intermediates are highly reactive oxidants capable of activating strong C-H bonds of alkanes; the reactivity of the iron(III) iodosylarene intermediates is much greater than that of the corresponding iron(IV) oxo complex. The electrophilic character of the iron(III) iodosylarene complexes is demonstrated in sulfoxidation reactions. PMID:24820976

  20. The pre-melt phase of n-alkanes: Crystallographic evidence for a kinked chain structure

    PubMed Central

    Dorset, D. L.; Moss, B.; Wittmann, J. C.; Lotz, B.

    1984-01-01

    Electron diffraction measurements on epitaxially grown crystals of orthorhombic n-hexatriacontane, n-C36H74, give evidence for the chain-defect mechanism for linear chain melting. The derived structural model is also in accord with recent spectroscopic studies of odd-chain n-alkanes, and the diffraction data specifically exclude models based on helices or rigid chain rotors. Stability of a kinked chain structure, moreover, is indicated by an observed hysteresis effect that gives different pretransition temperatures for solution-grown and annealed crystals. Images PMID:16593438

  1. PEROXYNITRITE CHEMISTRY

    SciTech Connect

    Lymar, S.V.

    2000-11-29

    This century old area of research has been experiencing a renaissance during the last decade, with the annual number of publications on the subject increasing from only one in 1990 to nearly 200 in the late-1990s. This renewed interest is stimulated by the discovery of biological roles of nitric oxide, distinguished by the 1998 Nobel prize, and the recognition that the conversion of nitric oxide into peroxynitrite may play major roles in human diseases associated with oxidative stress and in cellular defense against invading pathogens. Peroxynitrite (ONOO{sup {minus}})is a structural isomer of nitrate (NO{sub 3}{sup {minus}}) that contains a peroxo bond. The physiological route to ONOO{sup {minus}} is provided by the combination of nitric oxide ({center_dot}NO) with superoxide ({center_dot}O{sub 2}{sup {minus}}), an extremely rapid reaction occurring upon every encounter of these radicals (the upper dot denotes radical species). Both {center_dot}NO and {center_dot}O{sub 2}{sup {minus}} are the oxygen metabolic products simultaneously generated in a number of cell types within a human body. Compared to its precursors, peroxynitrite is a much stronger oxidant capable of oxidizing proteins, nucleic acids, and lipids.

  2. Delights of Chemistry

    NSDL National Science Digital Library

    Developed by the University of Leeds, the Delights of Chemistry promotes the art of chemistry demonstrations. Users can find illustrations and explanations of forty chemistry experiments. Many animations of demonstrations including the magnesium lamp, thermite reaction, and the volcano reaction are available. The website is full of pictures of chemistry equipment and scientists at work. Through this site, students and educators are able to explore fun chemistry experiments without having to worry about the many hazards associated with working with chemicals.

  3. Upgrading light hydrocarbons via tandem catalysis: a dual homogeneous Ta/Ir system for alkane/alkene coupling.

    PubMed

    Leitch, David C; Lam, Yan Choi; Labinger, Jay A; Bercaw, John E

    2013-07-17

    Light alkanes and alkenes are abundant but are underutilized as energy carriers because of their high volatility and low energy density. A tandem catalytic approach for the coupling of alkanes and alkenes has been developed in order to upgrade these light hydrocarbons into heavier fuel molecules. This process involves alkane dehydrogenation by a pincer-ligated iridium complex and alkene dimerization by a Cp*TaCl2(alkene) catalyst. These two homogeneous catalysts operate with up to 60/30 cooperative turnovers (Ir/Ta) in the dimerization of 1-hexene/n-heptane, giving C13/C14 products in 40% yield. This dual system can also effect the catalytic dimerization of n-heptane (neohexene as the H2 acceptor) with cooperative turnover numbers of 22/3 (Ir/Ta). PMID:23799786

  4. Axial Chiral Bisbenzophenazines: Solid-State Self-Assembly via Halide Hydrogen Bonds Triggered by Linear Alkanes

    PubMed Central

    2015-01-01

    An axial chiral tetrachlorinated bisbenzo[a]phenazine has been discovered that undergoes an alkane-induced shift in the solid state from a disordered amorphous form to an ordered polycrystalline form. This phase transition is caused by the formation of pores that accommodate linear alkanes of varying lengths with a very strong affinity as judged by differential scanning calorimetry. Single crystal X-ray structure analysis revealed that a series of weak phenolic OHCl hydrogen bonds dictates the pore structure. These weak interactions can be disrupted mechanically, causing the material to revert to the amorphous form. Notably, the interchange between the amorphous and crystalline forms is readily reversible and is easily observed by characteristic colorimetric changes. Measurements via photoimage processing reveal that the degree of color change is dictated by the type of alkane employed. PMID:25019179

  5. Legendre Functions Quantum Chemistry: Chemistry 180-345A

    E-print Network

    Ronis, David M.

    Legendre Functions Quantum Chemistry: Chemistry 180-345A In class we showed that the the angular Fall 2003 #12;Quantum Chemistry -2- Chemistry 180-345A which is divergent at x = 1 (i.e., at = 0 Chemistry -3- Chemistry 180-345A Hydrogen orbitals for l = 0, 1 Fall 2003 #12;Quantum Chemistry -4

  6. Energy conversion alternatives study

    NASA Technical Reports Server (NTRS)

    Shure, L. T.

    1979-01-01

    Comparison of coal based energy systems is given. Study identifies and compares various advanced energy conversion systems using coal or coal derived fuels for baselaoad electric power generation. Energy Conversion Alternatives Study (ECAS) reports provede government, industry, and general public with technically consistent basis for comparison of system's options of interest for fossilfired electric-utility application.

  7. The Conversation Class

    ERIC Educational Resources Information Center

    Jackson, Acy L.

    2012-01-01

    The conversation class occupies a unique place in the process of learning English as a second or foreign language. From the author's own experience in conducting special conversation classes with Persian-speaking adults, he has drawn up a number of simple but important guidelines, some of which he hopes may provide helpful suggestions for the

  8. Power conversion: Overview

    Microsoft Academic Search

    J. P. Layton

    1982-01-01

    The central position of power conversion systems in relation to other elements of space power systems is identified and the recognized types of power conversion are shown to be: photovoltaic, thermoelectric, Brayton cycle, Rankine cycle, Stirling cycle, thermionic and electromagnetic. The requirement for space electric power levels versus calendar years are presented historically and projected beyond the turn of the

  9. Conversations in Child Care

    ERIC Educational Resources Information Center

    Bardige, Betty; Segal, Marilyn

    2004-01-01

    In this article, Bardige and Segal discuss how teachers can help a toddler's language and literacy development through conversation. They suggest an array of tactics, from asking young children open-ended, intellectually challenging questions to going beyond the here and now when carrying on a conversation. Research has shown that the practice of

  10. Film Screening and Conversation

    E-print Network

    Mathis, Wayne N.

    Film Screening and Conversation 2011 6-9pm Smithsonian Asian Paci c American Program Rasmuson Director John Sayles Film Run Time: 124 minutes Closest Metro: L'Enfant Plaza Related Traveling Exhibition, the Smithsonian Asian Pacific American Program presents a screening of the film Amigo and a conversation

  11. Computation as Conversation

    Microsoft Academic Search

    Johan van Benthem

    1998-01-01

    Against the backdrop of current research into 'logical dynamics' of information, we discuss two-way connections between conversation and computation. This leads to a broader perspective on both, using ideas from both computational and philosophical logic. In particular, we discuss merges between computation and conversation (or more general interaction) by means of three transformations on given algorithms: 'epistemization', 'dynamification', and 'gamification'.

  12. The Use of a Combination of alkB Primers to Better Characterize the Distribution of Alkane-Degrading Bacteria

    PubMed Central

    Jurelevicius, Diogo; Alvarez, Vanessa Marques; Peixoto, Raquel; Rosado, Alexandre S.; Seldin, Lucy

    2013-01-01

    The alkane monooxygenase AlkB, which is encoded by the alkB gene, is a key enzyme involved in bacterial alkane degradation. To study the alkB gene within bacterial communities, researchers need to be aware of the variations in alkB nucleotide sequences; a failure to consider the sequence variations results in the low representation of the diversity and richness of alkane-degrading bacteria. To minimize this shortcoming, the use of a combination of three alkB-targeting primers to enhance the detection of the alkB gene in previously isolated alkane-degrading bacteria was proposed. Using this approach, alkB-related PCR products were detected in 79% of the strains tested. Furthermore, the chosen set of primers was used to study alkB richness and diversity in different soils sampled in Carmpolis, Brazil and King George Island, Antarctica. The DNA extracted from the different soils was PCR amplified with each set of alkB-targeting primers, and clone libraries were constructed, sequenced and analyzed. A total of 255 alkB phylotypes were detected. Venn diagram analyses revealed that only low numbers of alkB phylotypes were shared among the different libraries derived from each primer pair. Therefore, the combination of three alkB-targeting primers enhanced the richness of alkB phylotypes detected in the different soils by 45% to 139%, when compared to the use of a single alkB-targeting primer. In addition, a dendrogram analysis and beta diversity comparison of the alkB composition showed that each of the sampling sites studied had a particular set of alkane-degrading bacteria. The use of a combination of alkB primers was an efficient strategy for enhancing the detection of the alkB gene in cultivable bacteria and for better characterizing the distribution of alkane-degrading bacteria in different soil environments. PMID:23825163

  13. Calorimetric Study of Adsorption of Alkanes in High-Silica Zeolites Scott Savitz, Flor Siperstein, Raymond J. Gorte, and Alan L. Myers

    E-print Network

    Siperstein, Flor R.

    and adsorption isotherms were measured for combinations of three alkanes (methane, ethane, propane) on a series Section Isosteric heats of adsorption and adsorption isotherms were measured for aCalorimetric Study of Adsorption of Alkanes in High-Silica Zeolites Scott Savitz, Flor Siperstein

  14. Oxidation of Methyl tertButyl Ether by Alkane Hydroxylase in Dicyclopropylketone-Induced and n-Octane-Grown Pseudomonas putida GPo1

    Microsoft Academic Search

    Christy A. Smith; Michael R. Hyman

    2004-01-01

    The alkane hydroxylase enzyme system in Pseudomonas putida GPo1 has previously been reported to be unreactive toward the gasoline oxygenate methyl tert-butyl ether (MTBE). We have reexamined this finding by using cells of strain GPo1 grown in rich medium containing dicyclopropylketone (DCPK), a potent gratuitous inducer of alkane hydroxylase activity. Cells grown with DCPK oxidized MTBE and generated stoichiometric quantities

  15. Quadrature frequency conversion

    NASA Astrophysics Data System (ADS)

    Eimerl, David

    1987-08-01

    A technique for frequency conversion of high-power lasers is described which uses two crystals for each conversion step rather than one. The two crystals are oriented so that the waves generated in them are orthogonally polarized. The conversion efficiency of these quadrature arrangements is much less sensitive to laser pulse nonuniformities than that in single-crystal methods. Consequently, very high conversion efficiency is possible for typically nonuniform laser pulses. Realization of the quadrature concept for all types of nonlinear optical processes is described. Data taken on second harmonic generation of Gaussian pulses shows that very high (internal) conversion efficiency is possible (greater than 95 percent) over a substantial range of input energy.

  16. Industrial Chemistry and School Chemistry: Making Chemistry Studies More Relevant

    ERIC Educational Resources Information Center

    Hofstein, Avi; Kesner, Miri

    2006-01-01

    In this paper, we present the development and implementation over the period of more than 15 years of learning materials focusing on industrial chemistry as the main theme. The work was conducted in the Department of Science Teaching at the Weizmann Institute of Science, Israel. The project's general goal was to teach chemistry concepts in the

  17. Changes in fluorescent emission of cationic fluorophores in the presence of n-alkanes and alcohols in different polarity solvents

    NASA Astrophysics Data System (ADS)

    Delgado-Camn, Arantzazu; Garriga, Rosa; Mateos, Elena; Cebolla, Vicente L.; Galbn, Javier; Membrado, Luis; Marcos, Susana de; Glvez, Eva M.

    2011-01-01

    Berberine and coralyne experience either fluorescence enhancement or quenching when long hydrocarbon chain compounds (e.g., n-alkanes or alcohols) are added to their solutions, depending on solvent polarity. In polar solvents, as methanol or acetonitrile, the added compounds provide an apolar microenvironment that hinders alternative relaxation mechanisms, favouring fluorescence emission. However, alkane additions produce quenching in dichloromethane, which has been explained taking into account ion pairing between cationic fluorophore and counterion. The strong quenching measured after alcohol additions in dichloromethane suggests reversed micelle formation. Procedures and results described here may find practical applications in the development of analytical methods.

  18. Re-evaluating the isotopic divide between angiosperms and gymnosperms using n-alkane delta13C values

    Microsoft Academic Search

    R. T. Bush; F. A. McInerney

    2009-01-01

    Angiosperm delta13C values are typically 1-30\\/00 more negative than those of co-occurring gymnosperms. This is known for both bulk leaf and compound-specific values from n-alkanes, which are stable, straight-chain hydrocarbons (C23-C35) found in the epicuticular leaf wax of vascular plants. For n-alkanes, there is a second distinction between the delta13C values of angiosperms and gymnosperms---delta13C values generally decrease with increasing

  19. Concentrations and ?(2)H values of cuticular n-alkanes vary significantly among plant organs, species and habitats in grasses from an alpine and a temperate European grassland.

    PubMed

    Gamarra, Bruno; Kahmen, Ansgar

    2015-08-01

    n-Alkanes are long-chained hydrocarbons contained in the cuticle of terrestrial plants. Their hydrogen isotope ratios (?(2)H) have been used as a proxy for environmental and plant ecophysiological processes. Calibration studies designed to resolve the mechanisms that determine the ?(2)H values of n-alkanes have exclusively focused on n-alkanes derived from leaves. It is, however, unclear in which quantities n-alkanes are also produced by other plant organs such as roots or inflorescences, or whether different plant organs produce distinct n-alkane ?(2)H values. To resolve these open questions, we sampled leaves, sheaths, stems, inflorescences and roots from a total of 15 species of European C3 grasses in an alpine and a temperate grassland in Switzerland. Our data show slightly increased n-alkane concentrations and n-alkane ?(2)H values in the alpine compared to the temperate grassland. More importantly, inflorescences had typically much higher n-alkane concentrations than other organs while roots had very low n-alkane concentrations. Most interestingly, the ?(2)H values of the carbon autonomous plant organs leaves, sheaths and stems were in general depleted compared to the overall mean ?(2)H value of a species, while non-carbon autonomous organs such as roots and inflorescences show ?(2)H values that are higher compared to the overall mean ?(2)H value of a species. We attribute organ-specific ?(2)H values to differences in the H-NADPH biosynthetic origin in different plant organs as a function of their carbon relationships. Finally, we employed simple mass balance calculations to show that leaves are in fact the main source of n-alkanes in the sediment. As such, studies assessing the environmental and physiological drivers of n-alkanes that focus on leaves produce relationships that can be employed to interpret the ?(2)H values of n-alkanes derived from sediments. This is despite the significant differences that we found among the ?(2)H values in the different plant organs. Our study brings new insights into the natural variability of n-alkane ?(2)H values and has implications for the interpretation of n-alkane ?(2)H values in ecological and paleohydrological research. PMID:25761443

  20. Chemistry Rocks: Redox Chemistry as a Geologic Tool.

    ERIC Educational Resources Information Center

    Burns, Mary Sue

    2001-01-01

    Applies chemistry to earth science, uses rocks in chemistry laboratories, and teaches about transition metal chemistry, oxidation states, and oxidation-reduction reactions from firsthand experiences. (YDS)

  1. Competitive adsorption of thiolated poly(ethylene glycol) and alkane-thiols on gold nanoparticles and its effect on cluster formation.

    PubMed

    Larson-Smith, Kjersta; Pozzo, Danilo C

    2012-09-18

    The surface concentration and conformation of thiol-terminated poly(ethylene glycol) (PEG) on gold nanoparticles are studied before and after coadsorption of alkane-thiols. Thermogravimetric analysis (TGA) indicates alkane-thiol ligands will competitively adsorb on gold surfaces of nanoparticles and that the extent of PEG-thiol replacement depends on the specific length of the alkane-thiol molecule. The conformation of the polymer is also affected by the length and packing density of the alkane-thiol. Dynamic light scattering (DLS) shows that the hydrodynamic size of coated particles has an intermediate maximum for the adsorption of octane-thiol, which also forms the most densely packed alkane-thiol monolayers. These two factors greatly impact the formation of clusters by nanoparticle surfactants. Small angle X-ray scattering (SAXS) shows that the largest clusters are formed when particles have a low PEG-thiol surface concentration and an extended PEG conformation. PMID:22924831

  2. MChem (Single Honours Degrees) Chemistry with External Placement

    E-print Network

    Brierley, Andrew

    with Mathematics MSci (Joint Honours Degree) Chemistry and Physics BSc (Single Honours Degrees) Chemistry Chemistry62 Chemistry MChem (Single Honours Degrees) Chemistry Chemistry with External Placement Chemistry with Medicinal Chemistry Chemistry with Medicinal Chemistry and External Placement Materials Chemistry Materials

  3. Molecular dynamics insight to phase transition in n-alkanes with carbon nanofillers

    NASA Astrophysics Data System (ADS)

    Rastogi, Monisha; Vaish, Rahul

    2015-05-01

    The present work aims to investigate the phase transition, dispersion and diffusion behavior of nanocomposites of carbon nanotube (CNT) and straight chain alkanes. These materials are potential candidates for organic phase change materials(PCMs) and have attracted flurry of research recently. Accurate experimental evaluation of the mass, thermal and transport properties of such composites is both difficult as well as economically taxing. Additionally it is crucial to understand the factors that results in modification or enhancement of their characteristic at atomic or molecular level. Classical molecular dynamics approach has been extended to elucidate the same. Bulk atomistic models have been generated and subjected to rigorous multistage equilibration. To reaffirm the approach, both canonical and constant-temperature, constant- pressure ensembles were employed to simulate the models under consideration. Explicit determination of kinetic, potential, non-bond and total energy assisted in understanding the enhanced thermal and transport property of the nanocomposites from molecular point of view. Crucial parameters including mean square displacement and simulated self diffusion coefficient precisely define the balance of the thermodynamic and hydrodynamic interactions. Radial distribution function also reflected the density variation, strength and mobility of the nanocomposites. It is expected that CNT functionalization could improve the dispersion within n-alkane matrix. This would further ameliorate the mass and thermal properties of the composite. Additionally, the determined density was in good agreement with experimental data. Thus, molecular dynamics can be utilized as a high throughput technique for theoretical investigation of nanocomposites PCMs.

  4. The anesthetic effect of alcohols and alkanes in caenorhabditis elegans (C. E. )

    SciTech Connect

    Anton, A.H.; Berk, A.I.; Nicholls, C.H. (Case Western Reserve Univ., Cleveland, OH (United States))

    1991-03-11

    The authors colleagues reported that the non-parasitic roundworm, C.E., was reversibly immobilized by volatile anesthetics, whose potencies were directly related to their lipid solubilities as in other animals. In further studies on this phenomenon, they tested a homologous series of organic solvents, to determine whether they also had a reversible anesthetic effect in C.E. as in other animals. Synchronized 3-1/2 day-old cultures of about 100 worms each were exposed to increasing concentrations of the alcohols (C{sub 1} - C{sub 14}) and alkanes (C{sub 5} -C{sub 10}) in 15 ml sealed bottles in a volume of 0.5 ml. The dose that reversibly immobilized 50% of the worms was determined and a straight line was plotted against the octanol/water partition coefficient (K) of each series. As with other animals, potency was directly related to the lipid solubility of these agents so that, for example, the ID{sub 50} for methanol was 1,000 mmol (K=0.12) whereas it was 0.17 mmol for heptanol (K=3,000). The alcohols were about 20 times more potent than the alkanes even though the latter were about 10 times more lipid soluble than the alcohols. In spite of these differences, the cut-off point was at C{sub 9} in the two series.

  5. Optimizing catalysis conditions to decrease aromatic hydrocarbons and increase alkanes for improving jet biofuel quality.

    PubMed

    Cheng, Jun; Li, Tao; Huang, Rui; Zhou, Junhu; Cen, Kefa

    2014-04-01

    To produce quality jet biofuel with high amount of alkanes and low amount of aromatic hydrocarbons, two zeolites of HY and HZSM-5 supporting Ni and Mo were used as catalysts to convert soybean oil into jet fuel. Zeolite HY exhibited higher jet range alkane selectivity (40.3%) and lower jet range aromatic hydrocarbon selectivity (23.8%) than zeolite HZSM-5 (13.8% and 58.9%). When reaction temperature increased from 330 to 390C, yield of jet fuel over Ni-Mo/HY catalyst at 4 MPa hydrogen pressure increased from 0% to 49.1% due to the shift of reaction pathway from oligomerization to cracking reaction. Further increase of reaction temperature from 390 to 410C resulted in increased yield of jet range aromatic hydrocarbons from 18.7% to 30%, which decreased jet fuel quality. A high yield of jet fuel (48.2%) was obtained at 1 MPa low hydrogen pressure over Ni (8 wt.%)-Mo (12 wt.%)/HY catalyst. PMID:24656484

  6. Recommended Vapor-Liquid Equilibrium Data. Part 2: Binary Alkanol-Alkane Systems

    NASA Astrophysics Data System (ADS)

    Gral, Marian; Oracz, Pawe?; Skrzecz, Adam; Bok, Andrzej; Ma̧czy?ski, Andrzej

    2003-12-01

    The recommended vapor-liquid equilibrium (VLE) data for 36 binary systems involving primary, secondary, and tertiary alcohols with n-alkanes and isoalkanes [with the exception of 1-alkanols-n-alkane systems, which were presented in Part 1 of this seriesJ. Phys. Chem. Ref. Data 31(3), 702 (2002)] have been obtained after critical evaluation of all data (744 data sets) reported in the open literature up to the middle of 2002. The evaluation procedure consisted in combining the thermodynamic consistency tests, data correlation, comparison with enthalpy of mixing data, and comparison of VLE data for various mixtures. The data were correlated with equations based on local compositions concept as well as with equation of state appended with chemical term (EoSC) proposed by Gral. The recommended data are presented in the form of sheets containing tables of data, figures and auxiliary information. Each sheet corresponds to one system and contains three isotherms (spaced by at least 15 K) and one isobar (preferably at 101.32 kPa). Experimental gaps were completed with the predicted data.

  7. Controlling Morphology and Molecular Packing of Alkane Substituted Phthalocyanine Blend Bulk Heterojunction Solar Cells

    PubMed Central

    Jurow, Matthew J.; Hageman, Brian A.; Nam, Chang-Yong; Pabon, Cesar; Black, Charles T.

    2013-01-01

    Systematic changes in the exocyclic substiution of core phthalocyanine platform tune the absorption properties to yield commercially viable dyes that function as the primary light absorbers in organic bulk heterojunction solar cells. Blends of these complementary phthalocyanines absorb a broader portion of the solar spectrum compared to a single dye, thereby increasing solar cell performance. We correlate grazing incidence small angle x-ray scattering structural data with solar cell performance to elucidate the role of nanomorphology of active layers composed of blends of phthalocyanines and a fullerene derivative. A highly reproducible device architecture is used to assure accuracy and is relevant to films for solar windows in urban settings. We demonstrate that the number and structure of the exocyclic motifs dictate phase formation, hierarchical organization, and nanostructure, thus can be employed to tailor active layer morphology to enhance exciton dissociation and charge collection efficiencies in the photovoltaic devices. These studies reveal that disordered films make better solar cells, short alkanes increase the optical density of the active layer, and branched alkanes inhibit unproductive homogeneous molecular alignment. PMID:23589766

  8. Oxidation of monohalogenated ethanes and n-chlorinated alkanes by whole cells of Nitrosomonas europaea.

    PubMed Central

    Rasche, M E; Hicks, R E; Hyman, M R; Arp, D J

    1990-01-01

    We have investigated the substrate specificity of ammonia monooxygenase in whole cells of the nitrifying bacterium Nitrosomonas europaea for a number of aliphatic halogenated hydrocarbons. To determine the effect of the halogen substituent and carbon chain length on substrate reactivity, we measured the rates of oxidation of the monohalogenated ethanes (fluoroethane, chloroethane, bromoethane, and iodoethane) and n-chlorinated C1 to C4 alkanes by whole cells of N. europaea. For monohalogenated ethanes, acetaldehyde was the major organic product and little or none of any of the alternate predicted products (2-halogenated alcohols) were detected. The maximum rate of haloethane oxidation increased with decreasing halogen molecular weight from iodoethane to chloroethane (19 to 221 nmol/min per mg of protein). In addition, the amount of substrate required for the highest rate of haloethane oxidation increased with decreasing halogen molecular weight. For the n-chlorinated alkanes, the rate of dechlorination, as measured by the appearance of the corresponding aldehyde product, was greatest for chloroethane and decreased dramatically for chloropropane and chlorobutane (118, 4, and 8 nmol of aldehyde formed per min per mg of protein, respectively). The concentration profiles for halocarbon oxidation by ammonia monooxygenase showed apparent substrate inhibition when ammonia was used as the reductant source. When hydrazine was used as the electron donor, no substrate inhibition was observed, suggesting that the inhibition resulted from reductant limitation. PMID:2394686

  9. Studies of dynamical layering in adsorbed alkane films by molecular dynamics simulations and quasielastic neutron scattering.

    NASA Astrophysics Data System (ADS)

    Hansen, F. Y.; Soza, P.; Diama, A.; Taub, H.; Volkmann, U. G.

    2007-03-01

    From experiments using a surface apparatus it is known that alkane fluids confined between two surfaces exhibit a layered structure at the molecular level. This static layering has motivated us to consider the possibility that the individual molecular layers in fluid alkane films adsorbed on a solid surface also exhibit different dynamical properties. Here we report molecular dynamics (MD) simulations of the diffusive motion in layers of tetracosane molecules (C24H50) (C24) adsorbed on graphite in time scales from 1 to 100 ps and from 1 to 4 ns and compare the results with high--energy-- resolution quasielastic neutron scattering spectra that probe motions on these time scales. The MD simulations are set up to answer the questions: a) is interlayer diffusion of C24 molecules significant on these time scales? b) are the diffusive motions in the layers different? and c) what is the nature of the diffusive motions observed in the high--energy--resolution quasielastic neutron scattering experiments using the Disk Chopper Spectrometer (1-100 ps) and the High Flux Backscattering Spectrometer (1-4 ns) at NIST?

  10. Evaluated Kinetics of the Reactions of H and CH3 with n-Alkanes: Experiments with n-Butane and a Combustion Model Reaction Network Analysis.

    PubMed

    Manion, Jeffrey A; Sheen, David A; Awan, Iftikhar A

    2015-07-16

    Presented is a combined experimental and modeling study of the kinetics of the reactions of H and CH3 with n-butane, a representative aliphatic fuel. Abstraction of H from n-alkane fuels creates alkyl radicals that rapidly decompose at high temperatures to alkenes and daughter radicals. In combustion and pyrolysis, the branching ratio for attack on primary and secondary hydrogens is a key determinant of the initial olefin and radical pool, and results propagate through the chemistry of ignition, combustion, and byproduct formation. Experiments to determine relative and absolute rate constants for attack of H and CH3 have been carried out in a shock tube between 859 and 1136 K for methyl radicals and 890 to 1146 K for H atoms. Pressures ranged from 140 to 410 kPa. Appropriate precursors are used to thermally generate H and CH3 in separate experiments under dilute and well-defined conditions. A mathematical design algorithm has been applied to select the optimum experimental conditions. In conjunction with postshock product analyses, a network analysis based on the detailed chemical kinetic combustion model JetSurf 2 has been applied. Polynomial chaos expansion techniques and Monte Carlo methods are used to analyze the data and assess uncertainties. The present results provide the first experimental measurements of the branching ratios for attack of H and CH3 on primary and secondary hydrogens at temperatures near 1000 K. Results from the literature are reviewed and combined with the present data to generate evaluated rate expressions for attack on n-butane covering 300 to 2000 K for H atoms and 400 to 2000 K for methyl radicals. Values for generic n-alkanes and related hydrocarbons are also recommended. The present experiments and network analysis further demonstrate that the C-H bond scission channels in butyl radicals are an order of magnitude less important than currently indicated by JetSurf 2. Updated rate expressions for butyl radical fragmentation reactions are provided. PMID:25871634

  11. X-Ray Scattering Study of Stuctures and Phase Transitions of Normal Alkanes

    NASA Astrophysics Data System (ADS)

    Shao, Honglin Henry

    A comprehensive study of the structures and phase transitions for normal alkanes is presented. Three different aspects are investigated: rotator phases in pure and mixed chain length normal alkanes; anomalous melting in alkane thin films; and nucleation in alkane emulsions. The structures of the five rotator phases are characterized with distortion, tilt and azimuthal order parameters. A new tilted rotator phase, R_{V}, is fully identified. The entropically favored lower packing density phases, rm R_{II}, R_{III}, and R_ {IV}, dominate at the high temperature, while increased packing density and distortion phases, R_{I} and R _{V}, are favored at the low temperature, as a result of the increasing importance of intermolecular interactions. Chain end effects modify this behavior by favoring tilted phases, rm R_{III}, R_{IV}, and R_{V}. The main effect of mixing is the increased stability of the rotator phases. Several universal trends are discovered in comparing the mixed-chain and single-chain materials: the normalized distortion in the R_{I} phase is reduced; the hexagonal R_{II} phase is favored over the R_{I} phase; and the tilted R_{V} phase is suppressed. A weakened coupling between layers caused by chain mixing is the origin of the modification of the rotator phase diagrams. A significant modification on melting of the n-tricosane (rm C_ {23}H_{48}) thin films is discovered. The melting of these thin films differs from that of bulk alkanes in two important ways. The melting temperature is depressed as the film thickness is reduced. The structures of solid rotator phases prior to melting change depending on the film thickness. The depression in the melting can be described by a simple mean field model. The nucleation kinetics of monodispersed emulsions of n- rm C_{15}H_{32}, n-rm C_{16}H_ {34}, and the C16-C17 mixtures, with sizes from ~0.1 to 10mu m, were characterized. Significant supercooling was discovered. A quench-depth dependent nucleation time lag is observed. A size dependence of melting is found among n-rm C_{16}H_ {34}, and the C16-C17 mixture emulsions, but not in n-C_{15}H_ {32} emulsions. The nucleation frequencies determined by time resolved x-ray scattering and differential scanning calorimetry are in good agreement with each other, which show significant deviation from the known theory. The liquid-to-crystal interfacial free energy of n- rm C_{16}H_{34} emulsions shows a slight size dependence. This is attributed to step nucleation, plausibly caused by the presence of surface and bulk nucleation, thus nucleation is a continuous process.

  12. Explicit modeling of organic chemistry and secondary organic aerosol partitioning for Mexico City and its outflow plume

    NASA Astrophysics Data System (ADS)

    Lee-Taylor, J.; Madronich, S.; Aumont, B.; Baker, A.; Camredon, M.; Hodzic, A.; Tyndall, G. S.; Apel, E.; Zaveri, R. A.

    2011-12-01

    The evolution of organic aerosols (OA) in Mexico City and its outflow is investigated with the nearly explicit gas phase photochemistry model GECKO-A (Generator of Explicit Chemistry and Kinetics of Organics in the Atmosphere), wherein precursor hydrocarbons are oxidized to numerous intermediate species for which vapor pressures are computed and used to determine gas/particle partitioning in a chemical box model. Precursor emissions included observed C3-10 alkanes, alkenes, and light aromatics, as well as larger n-alkanes (up to C25) not directly observed but estimated by scaling to particulate emissions according to their volatility. Conditions were selected for comparison with observations made in March 2006 (MILAGRO). The model successfully reproduces the magnitude and diurnal shape for both primary (POA) and secondary (SOA) organic aerosols, with POA peaking in the early morning at 15-20 ?g m-3, and SOA peaking at 10-15 ?g m-3 during mid-day. The majority (?75%) of the model SOA stems from reaction products of the large n-alkanes, used here as surrogates for all emitted hydrocarbons of similar volatility, with the remaining SOA originating mostly from the light aromatics. Simulated OA elemental composition reproduces observed H/C and O/C ratios reasonably well, although modeled ratios develop more slowly than observations suggest. SOA chemical composition is initially dominated by ?-hydroxy ketones and nitrates from the large alkanes, with contributions from peroxy acyl nitrates and, at later times when NOx is lower, organic hydroperoxides. The simulated plume-integrated OA mass continues to increase for several days downwind despite dilution-induced particle evaporation, since oxidation chemistry leading to SOA formation remains strong. In this model, the plume SOA burden several days downwind exceeds that leaving the city by a factor of >3. These results suggest significant regional radiative impacts of SOA.

  13. Explicit modeling of organic chemistry and secondary organic aerosol partitioning for Mexico City and its outflow plume

    NASA Astrophysics Data System (ADS)

    Lee-Taylor, J.; Madronich, S.; Aumont, B.; Camredon, M.; Hodzic, A.; Tyndall, G. S.; Apel, E.; Zaveri, R. A.

    2011-06-01

    The evolution of organic aerosols (OA) in Mexico City and its outflow is investigated with the nearly explicit gas phase photochemistry model GECKO-A (Generator of Explicit Chemistry and Kinetics of Organics in the Atmosphere), wherein precursor hydrocarbons are oxidized to numerous intermediate species for which vapor pressures are computed and used to determine gas/particle partitioning in a chemical box model. Precursor emissions included observed C3-10 alkanes, alkenes, and light aromatics, as well as larger n-alkanes (up to C25) not directly observed but estimated by scaling to particulate emissions according to their volatility. Conditions were selected for comparison with observations made in March 2006 (MILAGRO). The model successfully reproduces the magnitude and diurnal shape for both primary (POA) and secondary (SOA) organic aerosols, with POA peaking in the early morning at 15-20 ?g m-3, and SOA peaking at 10-15 ?g m-3 during mid-day. The majority (?75 %) of the model SOA stems from the large n-alkanes, with the remainder mostly from the light aromatics. Simulated OA elemental composition reproduces observed H/C and O/C ratios reasonably well, although modeled ratios develop more slowly than observations suggest. SOA chemical composition is initially dominated by ?-hydroxy ketones and nitrates from the large alkanes, with contributions from peroxy acyl nitrates and, at later times when NOx is lower, organic hydroperoxides. The simulated plume-integrated OA mass continues to increase for several days downwind despite dilution-induced particle evaporation, since oxidation chemistry leading to SOA formation remains strong. In this model, the plume SOA burden several days downwind exceeds that leaving the city by a factor of >3. These results suggest significant regional radiative impacts of SOA.

  14. Explicit modeling of organic chemistry and secondary organic aerosol partitioning for Mexico City and its outflow plume

    SciTech Connect

    Lee-Taylor, J.; Madronich, Sasha; Aumont, B.; Baker, A.; Camredon, M.; Hodzic, Alma; Tyndall, G. S.; Apel, Eric; Zaveri, Rahul A.

    2011-12-21

    The evolution of organic aerosols (OA) in Mexico City and its outflow is investigated with the nearly explicit gas phase photochemistry model GECKO-A (Generator of Explicit Chemistry and Kinetics of Organics in the Atmosphere), wherein precursor hydrocarbons are oxidized to numerous intermediate species for which vapor pressures are computed and used to determine gas/particle partitioning in a chemical box model. Precursor emissions included observed C3-10 alkanes, alkenes, and light aromatics, as well as larger n-alkanes (up to C25) not directly observed but estimated by scaling to particulate emissions according to their volatility. Conditions were selected for comparison with observations made in March 2006 (MILAGRO). The model successfully reproduces the magnitude and diurnal shape for both primary (POA) and secondary (SOA) organic aerosols, with POA peaking in the early morning at 15-20 ug m-3, and SOA peaking at 10-15 ?g m-3 during mid-day. The majority (> 75%) of the model SOA stems from the large n-alkanes, with the remainder mostly from the light aromatics. Simulated OA elemental composition reproduces observed H/C and O/C ratios reasonably well, although modeled ratios develop more slowly than observations suggest. SOA chemical composition is initially dominated by *- hydroxy ketones and nitrates from the large alkanes, with contributions from peroxy acyl nitrates and, at later times when NOx is lower, organic hydroperoxides. The simulated plume-integrated OA mass continues to increase for several days downwind despite dilution-induced particle evaporation, since oxidation chemistry leading to SOA formation remains strong. In this model, the plume SOA burden several days downwind exceeds that leaving the city by a factor of >3. These results suggest significant regional radiative impacts of SOA.

  15. The Renaissance of Non-Aqueous Uranium Chemistry.

    PubMed

    Liddle, Stephen T

    2015-07-20

    Prior to the year 2000, non-aqueous uranium chemistry mainly involved metallocene and classical alkyl, amide, or alkoxide compounds as well as established carbene, imido, and oxo derivatives. Since then, there has been a resurgence of the area, and dramatic developments of supporting ligands and multiply bonded ligand types, small-molecule activation, and magnetism have been reported. This Review 1)?introduces the reader to some of the specialist theories of the area, 2)?covers all-important starting materials, 3)?surveys contemporary ligand classes installed at uranium, including alkyl, aryl, arene, carbene, amide, imide, nitride, alkoxide, aryloxide, and oxo compounds, 4)?describes advances in the area of single-molecule magnetism, and 5)?summarizes the coordination and activation of small molecules, including carbon monoxide, carbon dioxide, nitric oxide, dinitrogen, white phosphorus, and alkanes. PMID:26079536

  16. TU KAISERSLAUTERN DEPARTMENT OF CHEMISTRY

    E-print Network

    Madlener, Klaus

    ............................................................................................44 PHYSICAL CHEMISTRY: Prof. Dr. M. Gerhards ....................................................................................................46 PHYSICAL CHEMISTRY: Prof. Dr. Dr. G. Niedner-Schatteburg...............................................................................48 PHYSICAL CHEMISTRY: PD Dr. C. Riehn ...........................................................................

  17. Pretreatment of lignocellulosic biomass using Fenton chemistry.

    PubMed

    Kato, Dawn M; Ela, Noelia; Flythe, Michael; Lynn, Bert C

    2014-06-01

    In an attempt to mimic white-rot fungi lignin degradation via in vivo Fenton chemistry, solution phase Fenton chemistry (10 g biomass, 176 mmol hydrogen peroxide and 1.25 mmol Fe(2+) in 200 mL of water) was applied to four different biomass feedstocks. An enzymatic saccharification of Fenton pretreated biomass showed an average 212% increase relative to untreated control across all four feedstocks (P<0.05, statistically significant). A microbial fermentation of the same Fenton pretreated biomass showed a threefold increase in gas production upon a sequential co-culture with Clostridium thermocellum and Clostridium beijerinckii. These results demonstrate the use of solution phase Fenton chemistry as a viable pretreatment method to make cellulose more bioavailable for microbial biofuel conversion. PMID:24759643

  18. Two-stage thermal conversion of inedible lipid feedstocks to renewable chemicals and fuels.

    PubMed

    Asomaning, Justice; Mussone, Paolo; Bressler, David C

    2014-04-01

    The aim of this work was to study the conversion of inedible, low cost lipid feedstocks to renewable hydrocarbons using a two stage thermal hydrolysis-pyrolysis method. Beef tallow, yellow grease, brown grease and cold pressed camelina oil were first hydrolyzed and the fatty acids produced were recovered and pyrolyzed in batch reactors. The pyrolysis products were identified and quantified using gas chromatography and mass spectrometry. The pyrolysis product yields were similar for all the feedstock used with the organic liquid fraction (OLF) accounting for 76-80% of the product. The OLF consisted predominantly of n-alkanes. Approximately 30% OLF constituted a gasoline-equivalent fraction and 50% a diesel fraction. Other fuel property test showed that the OLF met the specifications set out by the Canadian general standards board. This research demonstrated a novel two-stage thermal hydrolysis-pyrolysis conversion method for producing OLF from inedible and low-value lipids. PMID:24583215

  19. ADEPT: Efficient Power Conversion

    SciTech Connect

    None

    2011-01-01

    ADEPT Project: In todays increasingly electrified world, power conversionthe process of converting electricity between different currents, voltage levels, and frequenciesforms a vital link between the electronic devices we use every day and the sources of power required to run them. The 14 projects that make up ARPA-Es ADEPT Project, short for Agile Delivery of Electrical Power Technology, are paving the way for more energy efficient power conversion and advancing the basic building blocks of power conversion: circuits, transistors, inductors, transformers, and capacitors.

  20. Conversations in Child Care

    MedlinePLUS

    ... children during shared reading in a discussion about characters and events. For instance, ask children what they ... about unfamiliar or new words about what the characters are thinking and feeling Conversations in the child ...

  1. Avatar augmented online conversation

    E-print Network

    Vilhjlmsson, Hannes Hgni

    2003-01-01

    One of the most important roles played by technology is connecting people and mediating their communication with one another. Building technology that mediates conversation presents a number of challenging research and ...

  2. Responsive Teaching through Conversation

    ERIC Educational Resources Information Center

    Dozier, Cheryl; Garnett, Susan; Tabatabai, Simeen

    2011-01-01

    Conversations are the heart of responsive teaching. By talking with struggling learners, teachers can find out about their interests in order to design effective, personalized instruction; build relationships; work through complexities in teaching and learning; and celebrate successes.

  3. Photochemical Energy Conversion.

    ERIC Educational Resources Information Center

    Batschelet, William H.; George, Arnold

    1986-01-01

    Describes procedures for two demonstrations: (1) photochemical energy conversion using ferric oxalate actinometry and (2) liquification of gases using Freon 114. Safety precautions are given for both demonstrations, as are procedures and material specifications. (JM)

  4. Special Report: Brain Chemistry.

    ERIC Educational Resources Information Center

    Krassner, Michael B.

    1983-01-01

    Chemical actions in the brain result in cognitive, emotional, neuroendocrine, neuromuscular, and/or neurocirculatory effects. Developments in understanding brain chemistry are discussed, considering among others, neurotransmitter chemistry, neuropeptides, drugs and the brain, antidepressants, and actions of minor tranquilizers. (JN)

  5. Igniting Chemistry in Fireworks

    NSDL National Science Digital Library

    WGBH Educational Foundation

    2004-01-29

    Students learn about the concepts of spectral chemistry, combustion, and the nature of fire through the use of visually rich fireworks resources. Optional resources address chemical reactions for those who want a more advanced chemistry lesson.

  6. Solid-supported cross-metathesis and a formal alkane metathesis for the generation of biologically relevant molecules.

    PubMed

    Mndez, Luciana; Mata, Ernesto G

    2015-02-01

    Solid-phase synthetic strategies toward the generation of libraries of biologically relevant molecules were developed using olefin cross-metathesis as a key step. It is remarkably the formal alkane metathesis based on a one-pot, microwave-assisted, ruthenium-catalyzed cross-metathesis and reduction to obtain Csp3-Csp3 linkages. PMID:25569690

  7. Isolation and characterization of alkane degrading bacteria from petroleum reservoir waste water in Iran (Kerman and Tehran provenances).

    PubMed

    Hassanshahian, Mehdi; Ahmadinejad, Mohammad; Tebyanian, Hamid; Kariminik, Ashraf

    2013-08-15

    Petroleum products spill and leakage have become two major environmental challenges in Iran. Sampling was performed in the petroleum reservoir waste water of Tehran and Kerman Provinces of Iran. Alkane degrading bacteria were isolated by enrichment in a Bushnel-Hass medium, with hexadecane as sole source of carbon and energy. The isolated strains were identified by amplification of 16S rDNA gene and sequencing. Specific primers were used for identification of alkane hydroxylase gene. Fifteen alkane degrading bacteria were isolated and 8 strains were selected as powerful degradative bacteria. These 8 strains relate to Rhodococcus jostii, Stenotrophomonas maltophilia, Achromobacter piechaudii, Tsukamurella tyrosinosolvens, Pseudomonas fluorescens, Rhodococcus erythropolis, Stenotrophomonas maltophilia, Pseudomonas aeruginosa genera. The optimum concentration of hexadecane that allowed high growth was 2.5%. Gas chromatography results show that all strains can degrade approximately half of hexadecane in one week of incubation. All of the strains have alkane hydroxylase gene which are important for biodegradation. As a result, this study indicates that there is a high diversity of degradative bacteria in petroleum reservoir waste water in Iran. PMID:23790464

  8. Evidence that crude oil alkane activation proceeds by different mechanisms under sulfate-reducing and methanogenic conditions

    NASA Astrophysics Data System (ADS)

    Aitken, C. M.; Jones, D. M.; Maguire, M. J.; Gray, N. D.; Sherry, A.; Bowler, B. F. J.; Ditchfield, A. K.; Larter, S. R.; Head, I. M.

    2013-05-01

    Fumarate addition has been widely proposed as an initial step in the anaerobic oxidation of both aromatic and aliphatic hydrocarbons. Alkyl and aryl succinates have been reported as metabolites of hydrocarbon degradation in laboratory studies with both pure and enrichment cultures of sulfate-, nitrate-, and iron-reducing bacteria. In addition these compounds have been reported in samples from environments such as hydrocarbon contaminated aquifers where, in addition to the above redox processes, hydrocarbon degradation linked to methanogenesis was observed. Here we report data from anaerobic crude oil degrading microcosms which revealed significant differences between the acid metabolite profiles of crude oil degraded under sulfate-reducing or methanogenic conditions. Under sulfate-reducing conditions fumarate addition and the formation of alkylsuccinate metabolites was the principal mechanism for the anaerobic degradation of n-alkanes and branched chain alkanes. Other than alkyl succinates that represent indigenous metabolites in the sediment inoculum, alkyl succinate metabolites were never detected in sediment microcosms where methane generation was quantitatively linked to n-alkane degradation. This indicates that alternative mechanisms of alkane activation may operate under methanogenic conditions.

  9. Use of cuticular wax alkanes to estimate digestibility and intake of cows as pasture with a view to estimating efficiency.

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Determination of feed efficiency requires estimates of intake and digestibility of the diet, but they are difficult to measure on pasture. The objective of this research was to determine if plants cuticular alkanes were suitable as markers to estimate intake and diet digestibility of grazing cows wi...

  10. Algae Harvest Energy Conversion

    Microsoft Academic Search

    Yung-Tse Hung; O. Sarafadeen Amuda; A. Olanrewaju Alade; I. Adekunle Amoo; Stephen Tiong-Lee Tay; Kathleen Hung Li

    \\u000a Algae harvest energy conversion to biofuel technology is a promising alternative to fossil fuel that has inherent pollution\\u000a attachment. With present resources available for the microalgae mass production and hence, high oil yield, microalgal can\\u000a sufficiently be a new source of renewable energy to replace the fossil fuels. In this chapter, algae description, composition,\\u000a cultivation, its conversion to biofuel, and

  11. An Introduction to Chemistry: Nuclear Chemistry

    NSDL National Science Digital Library

    Mark Bishop

    This cost-free resource is a chapter from a textbook on introductory chemistry, developed for learners with little background in physics or chemistry. This chapter deals with the atomic nucleus and radiation, nuclear energy, and uses of radioactive substances. It is appropriate for teachers seeking additional content knowledge, high school physics and chemistry courses, and college-level preparatory chemistry. It builds a foundation to understand the physical forces in the nucleus (electrostatic force and strong force), and explains how chemical reactions differ from nuclear reactions. Graphs and diagrams depict what happens in radioactive decay. The section on chemical nuclear equations is straightforward and comprehensible for non-scientists. This collection is part of An Introduction to Chemistry, a set of resources developed by Mark Bishop which includes two textbooks, 15 animated tutorials, downloadable Power Point presentations for teachers, concept maps, and 3D molecular models.

  12. Chemistry -Bachelor of Science (SCH) Chemistry: ACS Certified

    E-print Network

    Chemistry - Bachelor of Science (SCH) Chemistry: ACS Certified Total Credits Required: 128 Required of the following courses Course Credits CH 1110 University Chemistry I 4 Course Credits AND CH 4110 Pharmaceutical Chemistry I 3 CH 1111 University Chemistry Lab I 1 CH 4120 Pharmaceutical Chemistry II 3 OR CH 4320

  13. Chemistry -Bachelor of Science (SCH) Chemistry: ACS Certified

    E-print Network

    Chemistry - Bachelor of Science (SCH) Chemistry: ACS Certified Total Credits Required: 128 Required of the following courses Course Credits CH 1150 University Chemistry I AND 3 Course Credits CH 1151 University Chemistry Lab I AND 1 CH 4110 Pharmaceutical Chemistry I 3 CH 1153 University Chemistry I Recitation 1 CH

  14. B.A. DEGREE REQUIREMENTS FOR CHEMISTRY (CHEMISTRY TRACK)

    E-print Network

    Doyle, Robert

    ) CHE 346: Physical Chemistry Lecture I (3) CHE 347: Physical Analytical Chemistry Laboratory (2) CHE 356: Physical Chemistry Lecture II (3) CHE 357: Physical Chemistry Laboratory (2) AND CHE 335 (1) CHE 427: Intermediate Organic Chemistry (3) CHE 436: Advanced Physical Chemistry (3) CHE 467

  15. The Chemistry Hypermedia Project

    NSDL National Science Digital Library

    These materials and documents are typical of those presented in an undergraduate course in general chemistry, analytical chemistry, and analytical instrumentation. Resources for educators include Excel spreadsheet simulations for analytical and physical chemistry, prototype JavaScripts and PERL scripts, lists of web workshops and publications, and links to the most recent papers and presentations from the Chemistry Hypermedia Project. There are also tutorials for equilibrium practice problems and analytical spectroscopy.

  16. Cyanobacterial aldehyde deformylase oxygenation of aldehydes yields n-1 aldehydes and alcohols in addition to alkanes

    PubMed Central

    Aukema, Kelly G.; Makris, Thomas M.; Stoian, Sebastian A.; Richman, Jack E.; Mnck, Eckard; Lipscomb, John D.; Wackett, Lawrence P.

    2013-01-01

    Aldehyde-deformylating oxygenase (ADO) catalyzes O2-dependent release of the terminal carbon of a biological substrate, octadecanal, to yield formate and heptadecane in a reaction that requires external reducing equivalents. We show here that ADO also catalyzes incorporation of an oxygen atom from O2 into the alkane product to yield alcohol and aldehyde products. Oxygenation of the alkane product is much more pronounced with C9-10 aldehyde substrates, so that use of nonanal as the substrate yields similar amounts of octane, octanal, and octanol products. When using doubly-labeled [1,2-13C]-octanal as the substrate, the heptane, heptanal and heptanol products each contained a single 13C-label in the C-1 carbons atoms. The only one-carbon product identified was formate. [18O]-O2 incorporation studies demonstrated formation of [18O]-alcohol product, but rapid solvent exchange prevented similar determination for the aldehyde product. Addition of [1-13C]-nonanol with decanal as the substrate at the outset of the reaction resulted in formation of [1-13C]-nonanal. No 13C-product was formed in the absence of decanal. ADO contains an oxygen-bridged dinuclear iron cluster. The observation of alcohol and aldehyde products derived from the initially formed alkane product suggests a reactive species similar to that formed by methane monooxygenase (MMO) and other members of the bacterial multicomponent monooxygenase family. Accordingly, characterization by EPR and Mssbauer spectroscopies shows that the electronic structure of the ADO cluster is similar, but not identical, to that of MMO hydroxylase component. In particular, the two irons of ADO reside in nearly identical environments in both the oxidized and fully reduced states, whereas those of MMOH show distinct differences. These favorable characteristics of the iron sites allow a comprehensive determination of the spin Hamiltonian parameters describing the electronic state of the diferrous cluster for the first time for any biological system. The nature of the diiron cluster and the newly recognized products from ADO catalysis hold implications for the mechanism of C-C bond cleavage. PMID:24490119

  17. Source apportionment of PAHs and n-alkanes in respirable particles in Tehran, Iran by wind sector and vertical profile.

    PubMed

    Moeinaddini, Mazaher; Esmaili Sari, Abbas; Riyahi bakhtiari, Alireza; Chan, Andrew Yiu-Chung; Taghavi, Seyed Mohammad; Hawker, Darryl; Connell, Des

    2014-06-01

    The vertical concentration profiles and source contributions of polycyclic aromatic hydrocarbons (PAHs) and n-alkanes in respirable particle samples (PM4) collected at 10, 100, 200 and 300-m altitude from the Milad Tower of Tehran, Iran during fall and winter were investigated. The average concentrations of total PAHs and total n-alkanes were 16.7 and 591 ng/m(3), respectively. The positive matrix factorization (PMF) model was applied to the chemical composition and wind data to apportion the contributing sources. The five PAH source factors identified were: 'diesel' (56.3% of total PAHs on average), 'gasoline' (15.5%), 'wood combustion, and incineration' (13%), 'industry' (9.2%), and 'road soil particle' (6.0%). The four n-alkane source factors identified were: 'petrogenic' (65% of total n-alkanes on average), 'mixture of petrogenic and biomass burning' (15%), 'mixture of biogenic and fossil fuel' (11.5%), and 'biogenic' (8.5%). Source contributions by wind sector were also estimated based on the wind sector factor loadings from PMF analysis. Directional dependence of sources was investigated using the conditional probability function (CPF) and directional relative strength (DRS) methods. The calm wind period was found to contribute to 4.4% of total PAHs and 5.0% of total n-alkanes on average. Highest average concentrations of PAHs and n-alkanes were found in the 10 and 100 m samples, reflecting the importance of contributions from local sources. Higher average concentrations in the 300 m samples compared to those in the 200 m samples may indicate contributions from long-range transport. The vertical profiles of source factors indicate the gasoline and road soil particle-associated PAHs, and the mixture from biogenic and fossil fuel source-associated n-alkanes were mostly from local emissions. The smaller average contribution of diesel-associated PAHs in the lower altitude samples also indicates that the restriction of diesel-fueled vehicle use in the central area of Tehran has been effective in reducing the PAHs concentration. PMID:24638832

  18. Size distribution and sources of trace metals and n-alkanes in the Athens urban aerosol during summer

    NASA Astrophysics Data System (ADS)

    Karanasiou, A. A.; Sitaras, I. E.; Siskos, P. A.; Eleftheriadis, K.

    Size-resolved, 24-h aerosol samples were collected from June-July 2001 by means of an Andersen high-volume cascade impactor. Sampling was conducted in a central avenue (Patission) characterised by heavy traffic, 21 m above street level, in the Athens city centre. Samples were analysed by atomic absorption spectrometry and gas chromatography to determine the size distribution of nine metallic elements (Cd, Pb, V, Ni, Mn, Cr, Cu, Fe, Al) and n-alkanes (with carbon numbers in the range 18-35). The aerosol mass median diameter (MMD) was calculated by means of probit analysis on the cumulative mass concentration size distribution for each metals and n-alkane. The total n-alkane mass concentration (TNA) in total suspended particles (TSP) ranged from 72 to 1506 ng m -3 while the total metal concentration ranged from 5.6 to 28.6 ?g m -3. The results showed that metals such as Cd, V and Ni are characterised by a MMD <1 ?m, while the MMD for Pb and Mn are 1 ?m. Such metals are generally considered to have anthropogenic emission sources. Other metals such as Al, Fe, Cu and Cr were found to have MMD=2-6 ?m, which generally originate from soil dust or mechanical abrasion processes. The Carbon number profile of n-alkane compounds showed a strong anthropogenic source with only a minor biogenic influence. The concentration of most n-alkanes was characterised by high variability during the sampling period, in contrast to the concentration of most trace metals. Most n-alkanes had a unimodal size distribution with MMD=1-2 ?m similar to those of some trace metals (Pb, Mn), which originate mostly from vehicle emissions. This is a strong indication that these species have a common source. Finally, gas-particle partitioning of n-alkanes was also examined for different particle sizes by means of the relationship between the partition constant Kp and saturation vapour pressure ( pL0) as proposed by current sorption models.

  19. Chemistry and Chemical Engineering

    E-print Network

    Paxton, Anthony T.

    2011 SCHOOL OF Chemistry and Chemical Engineering Information for Candidates APPOINTMENT OF PROFESSOR OF CHEMICAL ENGINEERING #12;#12;SCHOOL OF Chemistry and Chemical Engineering 3 Thank you for your 6-7 School of Chemistry and Chemical Engineering 8-9 Staff Profiles 10-11 Queen's and Northern

  20. CHEMISTRY 12500 Stephen Hoffmann

    E-print Network

    Jiang, Wen

    CHEMISTRY 12500 Fall 2014 Instructor Stephen Hoffmann Office = ARMS 1343 Phone = 765-494-5740 Email@purdue.edu Required Course Materials Chemistry: The Molecular Nature of Matter and Change, 6th Edition, by M. S. Silberberg, McGraw-Hill, 2014. [ISBN: 978-1-2593-79567] Chemistry 12500 Laboratory Manual, Fall 2014

  1. CHEMISTRY 12600 Spring 2014

    E-print Network

    Jiang, Wen

    CHEMISTRY 12600 Spring 2014 Professor Professor Gabriela C. Weaver WTHR laboratory each week. Required Course Materials Chemistry: The Molecular Nature of Matter and Change, 6th Ed., by M. S. Silberberg, McGraw-Hill, 2012. [ISBN: 978-0-07-340265-9] Chemistry 126 Laboratory

  2. Chemistry 171 Instructors

    E-print Network

    Chemistry 171 Fall 2004 Instructors Dr. George C. Schatz (lecturer) Nano 4018 (491-5657) schatz edition by Peter Atkins and Loretta Jones. General Chemistry Laboratory Manual, Stipes Publishing. Available through PLU (student chemistry group) or the Norris Center Bookstore: Laboratory notebook must

  3. Chemistry & Biology Perspective

    E-print Network

    Williams, Loren

    Chemistry & Biology Perspective The Origin of RNA and ``My Grandfather's Axe'' Nicholas V. Hud,1,* Brian J. Cafferty,1 Ramanarayanan Krishnamurthy,2 and Loren Dean Williams1 1School of Chemistry, Atlanta, GA 30332, USA 2Department of Chemistry, The Scripps Research Institute, La Jolla, CA 92037, USA

  4. CHEMISTRY 450 Spring, 2009

    E-print Network

    Stuart, Steven J.

    CHEMISTRY 450 Spring, 2009 Gautam Bhattacharyya, 363 Hunter Labs, phone: 656-1356 gautamb. This course does NOT have a separate laboratory meeting time. Course Goals CH 450 is the Chemistry Capstone course intended for chemistry majors in their final year of study. The main objectives for this course

  5. Chemistry for a SUSTAINABLE

    E-print Network

    Selloni, Annabella

    Viewpointt Chemistry for a SUSTAINABLE FUTURE MIGUEL GARCIA-GARIBAY UNIVERSITY OF CALIFORNIA LOS ON SUSTAINABIL- ITY AND CHEMISTRY, MAY 30JUNE 1, 2006, ARLINGTON, VA. VICKI H. GRASSIAN (CO-CHAIR) UNIVERSITY innovations do we need to achieve the goal of a sustainable future? Chemistry, a branch of science that deals

  6. Chemistry on Stamps.

    ERIC Educational Resources Information Center

    Schreck, James O.

    1986-01-01

    Suggests how postage stamps can be incorporated into chemistry teaching. Categories considered include emergence of chemistry as a science, metric system, atoms (and molecules and ions), stoichiometry, energy relationships in chemical systems, chemical bonding, nuclear chemistry, biochemistry, geochemistry, matter (gases, liquids, and solids),

  7. Analytical chemistry instrumentation

    SciTech Connect

    Laing, W.R.

    1986-01-01

    In nine sections, 48 chapters cover 1) analytical chemistry and the environment 2) environmental radiochemistry 3) automated instrumentation 4) advances in analytical mass spectrometry 5) fourier transform spectroscopy 6) analytical chemistry of plutonium 7) nuclear analytical chemistry 8) chemometrics and 9) nuclear fuel technology.

  8. Analytical chemistry instrumentation

    SciTech Connect

    Laing, W.R. (ed.)

    1986-01-01

    Separate abstracts were prepared for 48 papers in these conference proceedings. The topics covered include: analytical chemistry and the environment; environmental radiochemistry; automated instrumentation; advances in analytical mass spectrometry; Fourier transform spectroscopy; analytical chemistry of plutonium; nuclear analytical chemistry; chemometrics; and nuclear fuel technology. (LEW)

  9. Green Chemistry and Education.

    ERIC Educational Resources Information Center

    Hjeresen, Dennis L.; Schutt, David L.; Boese, Janet M.

    2000-01-01

    Many students today are profoundly interested in the sustainability of their world. Introduces Green Chemistry and its principles with teaching materials. Green Chemistry is the use of chemistry for pollution prevention and the design of chemical products and processes that are environmentally benign. (ASK)

  10. Mechanisms in Photographic Chemistry

    ERIC Educational Resources Information Center

    Sahyun, M. R. V.

    1974-01-01

    Reviews current research interests in photographic chemistry, involving two proposed models for spectral sensitization of crystal defects and impurities in the photolysis reactivity and the mechanisms of development and complexation. Establishment of photographic chemistry in a chemistry curriculum is recommended. (CC)

  11. Chemistry For Kids.

    ERIC Educational Resources Information Center

    Smith, Patricia J., Ed.

    1985-01-01

    Desribes a chemistry course (taught in summer for graduate credit) for K-6 teachers to help promote teaching of chemistry as an experimental science at the elementary school level. Also describes another chemistry course for elementary school teachers, focusing on the laboratory component and experiments. (JN)

  12. Reactions of FeOH/sup +/ and CoOH/sup +/ with alkanes in the gas phase

    SciTech Connect

    Cassady, C.J.; Freiser, B.S.

    1986-09-17

    The gas-phase reactions of FeOH/sup +/ and CoOH/sup +/ with aliphatic alkanes up to C/sub 6/H/sub 14/ were studied. As was the case in earlier studies on MH/sup +/ and MCH/sub 3//sup +/ (M = Fe, Co), FeOH/sup +/ is found to be less reactive than CoOH/sup +/. For aliphatic alkanes, CoOH/sup +/ reacts with species larger than ethane, while FeOH/sup +/ only reacts with branched alkanes and hexane. Following initial C-H insertion, H/sub 2/O loss dominates the FeOH/sup +/ reactions. For CoOH/sup +/, however, H/sub 2/O loss leads to an activated Co/sup +/-alkyl complex which decomposes further. In addition, dehydrogenation with no H/sub 2/O elimination also occurs in contrast to FeH/sup +/, CoH/sup +/, and CoCH/sub 3//sup +/ with alkanes, where complete loss of the initial ligand is seen. Initial C-C insertion is also a major pathway leading to M(OH)(alkene)/sup +/ species, and for FeOH/sup +/, pressure-dependent adduct formation is also observed with hexane and several branched alkanes. Both FeOH/sup +/ and CoOH/sup +/ react with cyclopropane and cyclobutane by initial C-C insertion. For cyclopentane and cyclohexane, CoOH/sup +/ reacts exclusively by C-H insertion, while FeOH/sup +/ is unreactive. As expected on the basis of thermodynamic calculations, the overall reactivity of MOH/sup +/ is intermediate to that of MH/sup +/ and MCH/sub 3//sup +/.

  13. Progressive Degradation of Crude Oil n-Alkanes Coupled to Methane Production under Mesophilic and Thermophilic Conditions

    PubMed Central

    Cheng, Lei; Shi, Shengbao; Li, Qiang; Chen, Jianfa; Zhang, Hui; Lu, Yahai

    2014-01-01

    Although methanogenic degradation of hydrocarbons has become a well-known process, little is known about which crude oil tend to be degraded at different temperatures and how the microbial community is responded. In this study, we assessed the methanogenic crude oil degradation capacity of oily sludge microbes enriched from the Shengli oilfield under mesophilic and thermophilic conditions. The microbial communities were investigated by terminal restriction fragment length polymorphism (T-RFLP) analysis of 16S rRNA genes combined with cloning and sequencing. Enrichment incubation demonstrated the microbial oxidation of crude oil coupled to methane production at 35 and 55C, which generated 3.70.3 and 2.80.3 mmol of methane per gram oil, respectively. Gas chromatography-mass spectrometry (GC-MS) analysis revealed that crude oil n-alkanes were obviously degraded, and high molecular weight n-alkanes were preferentially removed over relatively shorter-chain n-alkanes. Phylogenetic analysis revealed the concurrence of acetoclastic Methanosaeta and hydrogenotrophic methanogens but different methanogenic community structures under the two temperature conditions. Candidate divisions of JS1 and WWE 1, Proteobacteria (mainly consisting of Syntrophaceae, Desulfobacteraceae and Syntrophorhabdus) and Firmicutes (mainly consisting of Desulfotomaculum) were supposed to be involved with n-alkane degradation in the mesophilic conditions. By contrast, the different bacterial phylotypes affiliated with Caldisericales, Shengli Cluster and Synergistetes dominated the thermophilic consortium, which was most likely to be associated with thermophilic crude oil degradation. This study revealed that the oily sludge in Shengli oilfield harbors diverse uncultured microbes with great potential in methanogenic crude oil degradation over a wide temperature range, which extend our previous understanding of methanogenic degradation of crude oil alkanes. PMID:25409013

  14. Progressive degradation of crude oil n-alkanes coupled to methane production under mesophilic and thermophilic conditions.

    PubMed

    Cheng, Lei; Shi, Shengbao; Li, Qiang; Chen, Jianfa; Zhang, Hui; Lu, Yahai

    2014-01-01

    Although methanogenic degradation of hydrocarbons has become a well-known process, little is known about which crude oil tend to be degraded at different temperatures and how the microbial community is responded. In this study, we assessed the methanogenic crude oil degradation capacity of oily sludge microbes enriched from the Shengli oilfield under mesophilic and thermophilic conditions. The microbial communities were investigated by terminal restriction fragment length polymorphism (T-RFLP) analysis of 16S rRNA genes combined with cloning and sequencing. Enrichment incubation demonstrated the microbial oxidation of crude oil coupled to methane production at 35 and 55C, which generated 3.70.3 and 2.80.3 mmol of methane per gram oil, respectively. Gas chromatography-mass spectrometry (GC-MS) analysis revealed that crude oil n-alkanes were obviously degraded, and high molecular weight n-alkanes were preferentially removed over relatively shorter-chain n-alkanes. Phylogenetic analysis revealed the concurrence of acetoclastic Methanosaeta and hydrogenotrophic methanogens but different methanogenic community structures under the two temperature conditions. Candidate divisions of JS1 and WWE 1, Proteobacteria (mainly consisting of Syntrophaceae, Desulfobacteraceae and Syntrophorhabdus) and Firmicutes (mainly consisting of Desulfotomaculum) were supposed to be involved with n-alkane degradation in the mesophilic conditions. By contrast, the different bacterial phylotypes affiliated with Caldisericales, "Shengli Cluster" and Synergistetes dominated the thermophilic consortium, which was most likely to be associated with thermophilic crude oil degradation. This study revealed that the oily sludge in Shengli oilfield harbors diverse uncultured microbes with great potential in methanogenic crude oil degradation over a wide temperature range, which extend our previous understanding of methanogenic degradation of crude oil alkanes. PMID:25409013

  15. [Eco-environmental evolution inferred from n-alkanes and delta13C records in the sediments of Shijiu Lake].

    PubMed

    Ou, Jie; Wang, Yan-Hua; Yang, Hao; Hu, Jian-Fang; Chen, Xia; Zou, Jun; Xie, Yun

    2013-02-01

    The study of global changes has focused on the reconstruction of paleovegetation and paleoclimate by n-alkanes and delta13C. 210Pb contents were measured for dating. The distribution characteristics of n-alkanes and delta13C were used to indicate the source of the organic matter in the sediments of Shijiu Lake. The relationship between modern eco-environmental evolution and human behaviors was discussed in this paper. The combination characteristics of n-alkanes showed a significant odd-even predominance in high-carbon number and main peak at C29, suggesting that the organic matter in the sediments were mainly derived from macrophytes and terrestrial higher plants. The delta13C contents of C27, C29 and C31 n-alkanes were analyzed. Results indicated that C3 plants are the dominant species. The distribution characteristics of n-alkanes and delta13C in different periods revealed the impact of human behaviors on Shijiu Lake. From 1862 to 1970, the low relative content of TOC, TN, C17-C25 and the light delta13C25-31 values showed that there were less human behaviors effects on Shijiu Lake and the eco-environment around the lake was stable. From 1970 to 1983, the relative content of TOC, TN and C17-C25 increased significantly, the delta13C25-31 values became weight. In this period, large areas of Shijiu Lake turned into farmland; pollution by fertilizers and pesticides was serious; large amounts of industrial and domestic wastewater were discharged into the lake. All these human behaviors resulted in the degradation of terrestrial higher plants around the lake. Meanwhile, the eutrophication levels were significantly increased. From 1983 to 2010, the relative contents of TOC, TN and C17-C25 were still in high-value ranges, the problem of eutrophication was not effectively controlled and the eco-environment of Shijiu Lake was relatively degradated. PMID:23668113

  16. Clean Fossil Energy Conversion Processes

    NASA Astrophysics Data System (ADS)

    Fan, L.-S.

    2007-03-01

    Absolute and per-capita energy consumption is bound to increase globally, leading to a projected increase in energy requirements of 50% by 2020. The primary source for providing a majority of the energy will continue to be fossil fuels. However, an array of enabling technologies needs to be proven for the realization of a zero emission power, fuel or chemical plants in the near future. Opportunities to develop new processes, driven by the regulatory requirements for the reduction or elimination of gaseous and particulate pollutant abound. This presentation describes the chemistry, reaction mechanisms, reactor design, system engineering, economics, and regulations that surround the utilization of clean coal energy. The presentation will cover the salient features of the fundamental and process aspects of the clean coal technologies in practice as well as in development. These technologies include those for the cleaning of SO2, H2S, NOx, and heavy metals, and separation of CO2 from the flue gas or the syngas. Further, new combustion and gasification processes based on the chemical looping concepts will be illustrated in the context of the looping particle design, process heat integration, energy conversion efficiency, and economics.

  17. Chemflex Overview: Common Chemistry core

    E-print Network

    Napier, Terrence

    see above Path A 28 see above and the following: 21 (for concentration) CHM 343 1 Physical chemistry laboratory CHM 341 4 Physical chemistry I CHM 342 4 Physical chemistry II CHM 334 3 Advanced chemistry Advanced chemistry elective BS Chemistry - Analytical/Physical Concentration Course Number Number

  18. Isolation and characterization of alkane-utilizing Nocardioides sp. strain CF8.

    PubMed

    Hamamura, N; Arp, D J

    2000-05-01

    A butane-utilizing bacterial strain CF8 was isolated and identified as a member of the genus Nocardioides from chemotaxonomic and 16S rDNA sequence analysis. Strain CF8 grew on alkanes ranging from C(2) to C(16) in addition to butane and various other substrates including primary alcohols, carboxylic acids, and phenol. Butane degradation by strain CF8 was inactivated by light, a specific inactivator of copper-containing monooxygenases. The unique thermal aggregation phenomenon of acetylene-binding polypeptides was also observed for strain CF8. These results suggest that butane monooxygenase in strain CF8 is a third example of the copper-containing monooxygenases previously described in ammonia oxidizers and methanotrophs. PMID:10779707

  19. Environmental and biosynthetic influences on carbon and hydrogen isotope ratios of leaf wax n-alkanes

    NASA Astrophysics Data System (ADS)

    McInerney, F. A.; Freeman, K. H.; Polissar, P. J.; Feakins, S. J.

    2013-12-01

    Both carbon and hydrogen isotope ratios of leaf-wax n-alkanes are influenced by the availability of water in a plant's growth environment. Carbon isotope ratios of bulk tissues in C3 plants demonstrate a strong inverse relationship with measures of available moisture (e.g. mean annual precipitation and precipitation/evaporation). Similarly, hydrogen isotope ratios of leaf wax n-alkanes (?Dl) can be enriched relative to precipitation (?Dw) by transpiration, which is related to relative humidity and the leaf-to-air vapor pressure deficit. Thus, D-enrichment of leaf-wax n-alkanes relative to precipitation, termed the apparent fractionation (2?l/w), becomes more positive with increasing aridity. In theory, more positive values of leaf-wax ?13C (?13Cl) and 2?l/w of leaf-wax n-alkanes should both correspond to more arid conditions in C3 plants. Here we review published and unpublished data on over 100 plants to examine this relationship. Contrary to expectations, C3 dicots show no clear relationship between ?13Cl and 2?l/w. This global lack of correlation is surprising given our understanding of aridity related isotopic effects in C3 plants. One possibility is that the implicit assumption of constant fractionation between lipid and bulk tissue is flawed due to the effects of different biosynthetic carriers and reaction pathways. We explore this possibility by examining the offset of leaf-wax carbon isotopes from the bulk leaf tissue (13?l/bulk). Different offsets would indicate additional biosynthetic processes are affecting ?13Cl in addition to any direct effects from aridity. We find that 13?l/bulk is highly variable, ranging from -1 to -16, which could explain the lack of correlation between ?13Cl and 2?l/w. In addition, 13?l/bulk values for C3 and C4 monocots (averages of -10.6 and -11.4 respectively) represent significantly greater offset between leaf wax and bulk tissue than in C3 dicots (average of -4.3), which is consistent with previous studies. Notably, 2?l/w and 13?l/bulk are positively correlated for all C3 plants, as well as for sub-divided C3 plant groups of dicots, monocots and gymnosperms. The positive relationship of 2?l/w and 13?l/bulk for C3 plants suggests co-varying influences of environmental properties on biosynthetic fractionation, such as root carbon storage use and water isotopes at the time of lipid synthesis. In contrast, C4 plants showed no correlation between 2?l/w and 13?l/bulk, which could signify differences in biosynthetic pathways or resource strategies between C3 and C4 plants. Paired leaf-wax carbon and hydrogen isotopic measurements have potential to elucidate isotope effects associated with ecohydrology and biosynthesis, which can strengthen paleoenvironmental interpretations of molecular isotopic data. Our analysis suggests both effects may be important determinants of plant-lipid isotope values.

  20. Phase equilibria calculations with a modified SAFT equation of state. 1: Pure alkanes, alkanols, and water

    SciTech Connect

    Kraska, T.; Gubbins, K.E. [Cornell Univ., Ithaca, NY (United States). School of Chemical Engineering] [Cornell Univ., Ithaca, NY (United States). School of Chemical Engineering

    1996-12-01

    The phase equilibria of the n-alkanes and the 1-alkanols have been calculated with the Lennard-Jones-SAFT equation of state of Mueller and Gubbins. This equation includes contributions from a dipole-dipole term, a modified association term, a chain term, and a Lennard-Jones term to account for monomer dispersion and overlap interactions. The influence of electrostatic forces due to the dipole moment has been investigated, and a simple treatment of the polarizability has been tested. It is shown by comparison with some sample calculations based on the renormalized perturbation theory that this approach is reasonable. The calculated phase equilibria are in good agreement with experimental data. The deviation between calculated and experimental data is significantly lower than for the original SAFT equation of state and a recently published chemical theory.

  1. Interaction of alkanes with an amorphous methanol film at 15-180 K

    SciTech Connect

    Souda, Ryutaro [Advanced Materials Laboratory, National Institute for Materials Science, 1-1 Namiki, Tsukuba, Ibaraki 305-0044 (Japan)

    2005-09-15

    The hydrogen-bond imperfections and glass-liquid transition of the amorphous methanol film have been investigated on the basis of the film dewetting and the incorporation/desorption of alkane molecules adsorbed on the surface. The butane is incorporated completely in the bulk of the porous methanol film up to 70 K. At least two distinct states exist for the incorporated butane; one is assignable to solvated molecules in the bulk and the other is weakly bound species at the surface or in the subsurface site. For the nonporous methanol film, the uptake of butane in the bulk is quenched but butane forms a surface complex with methanol above 80 K. The butane incorporated in the bulk of the glassy methanol film is released at 120 K, where dewetting of the methanol film occurs simultaneously due to evolution of the supercooled liquid phase.

  2. Dynamics of CN+alkane reactions by crossed-beam dc slice imaging

    SciTech Connect

    Huang Cunshun; Li Wen; Estillore, Armando D.; Suits, Arthur G. [Department of Chemistry, Wayne State University, Detroit, Michigan 48202 (United States)

    2008-08-21

    The hydrogen atom abstraction reactions of CN (X {sup 2}{sigma}{sup +}) with alkanes have been studied using the crossed molecular beam technique with dc slice ion imaging at collision energies of 7.5 and 10.8 kcal/mol. The product alkyl radical images were obtained via single photon ionization at 157 nm for the reactions of CN (X {sup 2}{sigma}{sup +}) with n-butane, n-pentane, n-hexane, and cyclohexane. From analysis of the images, we obtained the center-of-mass frame product angular distributions and translational energy distributions directly. The results indicate that the products are largely backscattered and that most of the available energy ({approx}80%-85%) goes to the internal energy of the products. The reaction dynamics is discussed in light of recent kinetics data, theoretical calculations, and results for related halogen and oxygen atom reactions.

  3. Recommended Vapor-Liquid Equilibrium Data. Part 1: Binary n-Alkanol-n-Alkane Systems

    NASA Astrophysics Data System (ADS)

    Gral, Marian; Oracz, Pawe?; Skrzecz, Adam; Bok, Andrzej; Ma̧czy?ski, Andrzej

    2002-09-01

    The recommended vapor-liquid equilibrium (VLE) data for 39 binary n-alcohol-n-alkane systems have been obtained after critical evaluation of all data (490 data sets) reported in the open literature up to the middle of 2001. The evaluation procedure consisted in combining the thermodynamic consistency tests, data correlation, comparison with enthalpy of mixing data, and comparison of VLE data for various mixtures. The data were correlated with equations based on the local compositions concept as well as with the equation of state appended with a chemical term (EoSC) proposed by Gral. The recommended data are presented in the form of individual pages containing tables of data, figures, and auxiliary information. Each page corresponds to one system and contains three isotherms (spaced by at least 15 K) and one isobar (preferably at 101.32 kPa). Experimental gaps were completed with the predicted data.

  4. Empirical and Semi-theoretical Methods for Predicting the Viscosity of Binary n-Alkane Mixtures

    NASA Astrophysics Data System (ADS)

    Yucel, H. G.

    2005-11-01

    In this study, empirical and semi-theoretical methods for predicting the viscosity of binary mixtures of n-alkanes are presented at atmospheric pressure and in the temperature range from 288 to 333 K. In the empirical viscosity calculation method, a modified version of the Andrade equation and a simple mixture rule are used. The proposed semi-theoretical method employs both the Enskogs hard-sphere theory for dense fluids and the principle of corresponding states. The viscosities of binary mixtures of n-heptane with n-hexane and n-nonane covering different compositions were calculated using these methods which require only critical properties and the normal boiling point as input data. The predictions were compared with accurate experimental data in the literature. Highly satisfactory results were obtained. The percent average absolute deviations amount to 1.2 and 0.9% utilizing the empirical and semi-theoretical viscosity methods, respectively, for 27 data points.

  5. Phase separation in the organic solid state : the influence of quenching protocol in unstable ?-alkane blends

    SciTech Connect

    Gilbert, E. P.; Nelson, A.; Sutton, D.; Terrill, N.; Martin, C.; Lal, J.; Lang, E.; Intense Pulsed Neutron Source; Bragg Inst.; Rutherford App. Lab.; Daresbury Lab.

    2005-01-01

    Blends of normal alkanes form lamellar structures, when quenched from the melt, in which the separation of the individual chains may be controlled by the chain-length mismatch, molar composition, isotopic substitution and confinement. 2:1 C{sub 28}H{sub 58}:C{sub 36}D{sub 74} mixtures have been investigated after subjection to a cooling rate varying over three orders of magnitude and intermediate annealing prior to reaching ambient. Quenching at 100 C/min yields similar behavior to intermediate annealing between the pure components' melting points. Slow cooling at 0.1 C/min generates significantly greater ordering and behavior comparable to that obtained from annealing mid-way between the mixing transition and the C{sub 28}H{sub 58} melting point.

  6. Insect attachment on crystalline bioinspired wax surfaces formed by alkanes of varying chain lengths.

    PubMed

    Gorb, Elena; Bhm, Sandro; Jacky, Nadine; Maier, Louis-Philippe; Dening, Kirstin; Pechook, Sasha; Pokroy, Boaz; Gorb, Stanislav

    2014-01-01

    The impeding effect of plant surfaces covered with three-dimensional wax on attachment and locomotion of insects has been shown previously in numerous experimental studies. The aim of this study was to examine the effect of different parameters of crystalline wax coverage on insect attachment. We performed traction experiments with the beetle Coccinella septempunctata and pull-off force measurements with artificial adhesive systems (tacky polydimethylsiloxane semi-spheres) on bioinspired wax surfaces formed by four alkanes of varying chain lengths (C36H74, C40H82, C44H90, and C50H102). All these highly hydrophobic coatings were composed of crystals having similar morphologies but differing in size and distribution/density, and exhibited different surface roughness. The crystal size (length and thickness) decreased with an increase of the chain length of the alkanes that formed these surfaces, whereas the density of the wax coverage, as well as the surface roughness, showed an opposite relationship. Traction tests demonstrated a significant, up to 30 fold, reduction of insect attachment forces on the wax surfaces when compared with the reference glass sample. Attachment of the beetles to the wax substrates probably relied solely on the performance of adhesive pads. We found no influence of the wax coatings on the subsequent attachment ability of beetles. The obtained data are explained by the reduction of the real contact between the setal tips of the insect adhesive pads and the wax surfaces due to the micro- and nanoscopic roughness introduced by wax crystals. Experiments with polydimethylsiloxane semi-spheres showed much higher forces on wax samples when compared to insect attachment forces measured on these surfaces. We explain these results by the differences in material properties between polydimethylsiloxane probes and tenent setae of C. septempunctata beetles. Among wax surfaces, force experiments showed stronger insect attachment and higher pull-off forces of polydimethylsiloxane probes on wax surfaces having a higher density of wax coverage, created by smaller crystals. PMID:25161838

  7. Band-selective ballistic energy transport in alkane oligomers: toward controlling the transport speed.

    PubMed

    Yue, Yuankai; Qasim, Layla N; Kurnosov, Arkady A; Rubtsova, Natalia I; Mackin, Robert T; Zhang, Hong; Zhang, Boyu; Zhou, Xiao; Jayawickramarajah, Janarthanan; Burin, Alexander L; Rubtsov, Igor V

    2015-05-28

    Intramolecular transport of vibrational energy in two series of oligomers featuring alkane chains of various length was studied by relaxation-assisted two-dimensional infrared spectroscopy. The transport was initiated by exciting various end-group modes (tags) such as different modes of the azido (?(N?N) and ?(N?N)), carboxylic acid (?(C?O)), and succinimide ester (?as(C?O)) with short mid-IR laser pulses. It is shown that the transport via alkane chains is ballistic and the transport speed is dependent on the type of the tag mode that initiates the transport. The transport speed of 8.0 /ps was observed when initiated by either ?(C?O) or ?as(C?O). When initiated by ?(N?N) and ?(N?N), the transport speed of 14.4 2 and 11 4 /ps was observed. Analysis of the vibrational relaxation channels of different tags, combined with the results for the group velocity evaluation, permits identification of the chain bands predominantly contributing to the transport for different cases of the transport initiation. For the transport initiated by ?(N?N) the CH2 twisting and wagging chain bands were identified as the major energy transport channels. For the transport initiated by ?(C?O), the C-C stretching and CH2 rocking chain bands served as major energy transporters. The transport initiated by ?(N?N) results in direct formation of the wave packet within the CH2 twisting and wagging chain bands. These developments can aid in designing molecular systems featuring faster and more controllable energy transport in molecules. PMID:25936983

  8. Alcohol, Chemistry and You

    NSDL National Science Digital Library

    Developed by Kennesaw State University, ChemCases.com is a series of curriculum units that link responsible decision making in product development with chemical principles taught in college General Chemistry. Alcohol, Chemistry and You, by Dr. Bill Boggan, is the latest offering by the Web site, which "looks at the chemistry of beverage alcohol (ethyl alcohol) through the eyes of a General Chemistry student." The fourteen chapter lessons cover everything from what ethyl alcohol is to alcohol addiction, relating it to various principles learned in a general chemistry course.

  9. Isomolybdate conversion coatings

    NASA Technical Reports Server (NTRS)

    Minevski, Zoran (Inventor); Maxey, Jason (Inventor); Nelson, Carl (Inventor); Eylem, Cahit (Inventor)

    2002-01-01

    A conversion coating solution and process forms a stable and corrosion-resistant layer on metal substrates or layers or, more preferably, on a boehmite layer or other base conversion coating. The conversion coating process involves contacting the substrate, layer or coating with an aqueous alkali metal isomolybdate solution in order to convert the surface of the substrate, layer or coating to a stable conversion coating. The aqueous alkali metal molybdates are selected from sodium molybdate (Na.sub.2 MoO.sub.4), lithium molybdate (Li.sub.2 MoO.sub.4), potassium molybdate (K.sub.2 MoO.sub.4), or combinations thereof, with the most preferred alkali metal molybdate being sodium molybdate. The concentration of alkali metal molybdates in the solution is preferably less than 5% by weight. In addition to the alkali metal molybdates, the conversion coating solution may include alkaline metal passivators selected from lithium nitrate (LiNO.sub.3), sodium nitrate (NaNO.sub.3), ammonia nitrate (NH.sub.4 NO.sub.3), and combinations thereof; lithium chloride, potassium hexafluorozirconate (K.sub.2 ZrF.sub.6) or potassium hexafluorotitanate (K.sub.2 TiF.sub.6).

  10. Laser energy conversion

    NASA Technical Reports Server (NTRS)

    Jalufka, N. W.

    1989-01-01

    The conversion of laser energy to other, more useful, forms is an important element of any space power transmission system employing lasers. In general the user, at the receiving sight, will require the energy in a form other than laser radiation. In particular, conversion to rocket power and electricity are considered to be two major areas where one must consider various conversion techniques. Three systems (photovoltaic cells, MHD generators, and gas turbines) have been identified as the laser-to-electricity conversion systems that appear to meet most of the criteria for a space-based system. The laser thruster also shows considerable promise as a space propulsion system. At this time one cannot predict which of the three laser-to-electric converters will be best suited to particular mission needs. All three systems have some particular advantages, as well as disadvantages. It would be prudent to continue research on all three systems, as well as the laser rocket thruster. Research on novel energy conversion systems, such as the optical rectenna and the reverse free-electron laser, should continue due to their potential for high payoff.

  11. Energy Conversion and Storage Program: 1992 Annual report

    SciTech Connect

    Cairns, E.J.

    1993-06-01

    This report is the 1992 annual progress report for the Energy Conversion and Storage Program, a part of the Energy and Environment Division of the Lawrence Berkeley Laboratory. Work described falls into three broad areas: electrochemistry; chemical applications; and materials applications. The Energy Conversion and Storage Program applies principles of chemistry and materials science to solve problems in several areas: (1) production of new synthetic fuels, (2) development of high-performance rechargeable batteries and fuel cells, (3) development of advanced thermochemical processes for energy conversion, (4) characterization of complex chemical processes and chemical species, and (5) study and application of novel materials for energy conversion and transmission. Projects focus on transport-process principles, chemical kinetics, thermodynamics, separation processes, organic and physical chemistry, novel materials, and advanced methods of analysis. Electrochemistry research aims to develop advanced power systems for electric vehicle and stationary energy storage applications. Chemical applications research includes topics such as separations, catalysis, fuels, and chemical analyses. Included in this program area are projects to develop improved, energy-efficient methods for processing product and waste streams from synfuel plants, coal gasifiers, and biomass conversion processes. Materials applications research includes evaluation of the properties of advanced materials, as well as development of novel preparation techniques. For example, techniques such as sputtering, laser ablation, and poised laser deposition are being used to produce high-temperature superconducting films.

  12. Harvard University Department of Chemistry and Chemical Biology

    E-print Network

    Heller, Eric

    Harvard University Department of Chemistry and Chemical Biology Safety Office, 226 Converse Lab 12 OF RISK AND RELEASE Non-Harvard Personnel Under the Age of 18 Using Harvard Research Laboratory, the undersigned, accept and agree to the following terms and conditions in consideration for my use of Harvard

  13. Coal science: An introduction to chemistry, technology and utilization

    SciTech Connect

    Hessley, R.K.; Reasoner, J.W.; Riley, J.T.

    1986-01-01

    This book presents the chemistry and geology of coal. It describes aspects of the petrology and petrographic characterization of coal, the processes involved in coal conversion and utilization, and the testing and analysis of coal. It includes recent statistics regarding production and utilization, as well as recent developments in structure, reactivity and routine analysis.

  14. Harvard University Department of Chemistry and Chemical Biology

    E-print Network

    Heller, Eric

    to the chemicals being used, and other devices relevant to the hazards being worked with. Wash hands before. "Reproductive Hazards in the Workplace." Handbook of Chemical Health and Safety. Ed. Robert J. AlaimoHarvard University Department of Chemistry and Chemical Biology Safety Office, 226 Converse Lab 12

  15. Influence of physiology and climate on ?D of leaf wax n-alkanes from C 3 and C 4 grasses

    NASA Astrophysics Data System (ADS)

    Smith, Francesca A.; Freeman, Katherine H.

    2006-03-01

    We measured hydrogen isotope compositions ( ?D) of high-molecular-weight n-alkanes (C 27-C 33) from grasses grown in greenhouses and collected from the US Great Plains. In both cases, n-alkanes from C 4 grasses are enriched in D by more than 20 relative to those from C 3 grasses. The apparent enrichment factor (?) between C 29n-alkane and greenhouse water is -165 12 for C 3 grasses and -140 15 for C 4 grasses. For samples from the Great Plains, ?D values of C 29n-alkanes range from -280 to -136, with values for C 4 grasses ca. 21 more positive than those for C 3 grasses from the same site. Differences in C 3 and C 4 grass n-alkane ?D values are consistent with the shorter interveinal distance in C 4 grass leaves, and greater back-diffusion of enriched water from stomata to veins, than in C 3 grass leaves. Great Plains' grass n-alkane isotopic ratios largely reflect precipitation ?D values. However, the offset or apparent fractionation between n-alkanes and precipitation is not uniform and varies with annual precipitation and relative humidity, suggesting climatic controls on lipid ?D values. The dryer sites exhibit smaller absolute apparent fractionation indicative of D-enrichment of source waters through transpiration and/or soil evaporation. To explore the relationship between climate and n-alkane ?D values, we develop three models. (1) The 'direct analog' model estimates ?D values simply by applying the apparent enrichment factors, ?, observed in greenhouse grasses to precipitation ?D values from the Great Plains. (2) The 'leaf-water' model uses a Craig-Gordon model to estimate transpirational D-enrichment for both greenhouse and field sites. The transpiration-corrected enrichment factors between C 29 and bulk leaf-water, ?, calculated from the greenhouse samples (-181 for C 3 and -157 for C 4) are applied to estimate ?D values relative to modeled bulk leaf-water ?D values. (3) The 'soil- and leaf-water' model estimates the combined effects of soil evaporation, modeled by analogy with a flow-through lake, and transpiration on ?D values. Predictions improve with the addition of the explicit consideration of transpiration and soil evaporation, indicating that they are both important processes in determining plant lipid ?D values. D-enrichment caused by these evaporative processes is controlled by relative humidity, suggesting that important climatic information is recorded in leaf wax n-alkane ?D values. Calibration studies such as this one provide a baseline for future studies of plant-water-deuterium systematics and form the foundation for interpretation of plant wax hydrogen isotope ratios as a paleo-aridity proxy.

  16. Direct conversion technology

    NASA Technical Reports Server (NTRS)

    Massier, Paul F.; Bankston, C. P.; Williams, R.; Underwood, M.; Jeffries-Nakamura, B.; Fabris, G.

    1989-01-01

    The overall objective of the Direct Conversion Technology task is to develop an experimentally verified technology base for promising direct conversion systems that have potential application for energy conservation in the end-use sectors. This report contains progress of research on the Alkali Metal Thermal-to-Electric Converter (AMTEC), and on the Two-Phase Liquid-Metal Magnetohydrodynamic Electrical Generator (LMMHD) for the period January 1, 1989 through December 31, 1989. Research on these concepts was initiated during October 1987. Reports prepared on previous occasions contain discussions on the following other direct conversion concepts: thermoelectric, pyroelectric, thermionic, thermophotovoltaic, thermoacoustic, thermomagnetic, thermoelastic (nitinol heat engines); and also, more complete discussions of AMTEC and LMMHD systems.

  17. Direct conversion technology

    SciTech Connect

    Massier, P.F.; Back, L.H.; Ryan, M.A.; Fabris, G.

    1992-01-07

    The overall objective of the Direct Conversion Technology task is to develop an experimentally verified technology base for promising direct conversion systems that have potential application for energy conservation in the end-use sectors. This report contains progress of research on the Alkali Metal Thermal-to-Electric Converter (AMTEC) and on the Two-Phase Liquid-Metal MHD Electrical Generator (LMMHD) for the period January 1, 1991 through December 31, 1991. Research on AMTEC and on LMMHD was initiated during October 1987. Reports prepared on previous occasions (Refs. 1--5) contain descriptive and performance discussions of the following direct conversion concepts: thermoelectric, pyroelectric, thermionic, thermophotovoltaic, thermoacoustic, thermomagnetic, thermoelastic (Nitionol heat engine); and also, more complete descriptive discussions of AMTEC and LMMHD systems.

  18. Measurement - Discovering Conversions

    NSDL National Science Digital Library

    2011-01-01

    Students measure a variety of objects in both metric and English systems. It is recommended that everyone in the group take each measurement and they then average them to obtain the most accurate measurement for the item. The next step is to create the ratios, convert them to decimals to two places and then average all the like decimals. Example all the measurements for the 5 small objects would be averaged to find the best estimate for the conversion factor for centimeters and inches. Using their conversion factors, they then convert a variety of measures. Finally, they are asked to look up the actual conversion factor and determine how accurately they were able to determine it.

  19. Direct conversion technology

    NASA Astrophysics Data System (ADS)

    Massier, P. F.; Back, L. H.; Ryan, M. A.; Fabris, G.

    1992-01-01

    The overall objective of the Direct Conversion Technology task is to develop an experimentally verified technology base for promising direct conversion systems that have potential application for energy conservation in the end-use sectors. This report contains progress of research on the Alkali Metal Thermal-to-Electric Converter (AMTEC) and on the Two-Phase Liquid-Metal MHD Electrical Generator (LMMHD) for the period 1 Jan. 1991 - 31 Dec. 1991. Research on AMTEC and on LMMHD was initiated during Oct. 1987. Reports prepared on previous occasions contain descriptive and performance discussions of the following direct conversion concepts: thermoelectric, pyroelectric, thermionic, thermophotovoltaic, thermoacoustic, thermomagnetic, thermoelastic (Nitionol heat engine); and also, more complete descriptive discussions of AMTEC and LMMHD systems.

  20. The chemistry of Venus' atmosphere

    NASA Technical Reports Server (NTRS)

    Sze, N. D.; Smith, W. H.

    1978-01-01

    A model for the Venus atmosphere involving photochemistry of oxygen, hydrogen, chlorine and sulfur species is presented. Sulfur reaction schemes and hydrogen and chlorine reaction schemes were included. The impact of sulfur on the oxygen budget and the subsequent production of H2SO4 molecules for the Venus cloud deck were explored. A major new reaction scheme for production of H2SO4 molecules involving sulfur and oxygen chemistry was established shown to dominate over the odd hydrogen scheme proposed earlier. The efficiency of the scheme in formation of H2SO4 is only about 50%, with the remaining sulfur residing in SO2 molecules. The calculated downward flux of H2SO4 may be sufficient to maintain a steady state sulfuric acid cloud if the resident time of H2SO4 droplets in the cloud is as long as a few years. If however, the resident time is half a year or shorter, additional chemistry capable of more efficient conversion of SO2 to SO3 is required.

  1. Somatization and conversion disorder.

    PubMed

    Hurwitz, Trevor A

    2004-03-01

    Somatization is the psychological mechanism whereby psychological distress is expressed in the form of physical symptoms. The psychological distress in somatization is most commonly caused by a mood disorder that threatens mental stability. Conversion disorder occurs when the somatic presentation involves any aspect of the central nervous system over which voluntary control is exercised. Conversion reactions represent fixed ideas about neurologic malfunction that are consciously enacted, resulting in psychogenic neurologic deficits. Treatment is complex and lengthy; it includes recovery of neurologic function aided by narcoanalysis and identification and treatment of the primary psychiatric disorder, usually a mood disorder. PMID:15101499

  2. Direct Conversion Technology

    SciTech Connect

    Back, L.H.; Fabris, G.; Ryan, M.A.

    1992-07-01

    The overall objective of the Direct Conversion Technology task is to develop an experimentally verified technology base for promising direct conversion systems that have potential application for energy conservation in the end-use sectors. Initially, two systems were selected for exploratory research and advanced development. These are Alkali Metal Thermal-to-Electric Converter (AMTEC) and Two-Phase Liquid Metal MD Generator (LMMHD). This report describes progress that has been made during the first six months of 1992 on research activities associated with these two systems. (GHH)

  3. Direct Conversion Technology

    NASA Astrophysics Data System (ADS)

    Back, L. H.; Fabris, G.; Ryan, M. A.

    1992-07-01

    The overall objective of the Direct Conversion Technology task is to develop an experimentally verified technology base for promising direct conversion systems that have potential application for energy conservation in the end-use sectors. Initially, two systems were selected for exploratory research and advanced development. These systems are the Alkali Metal Thermal-to-Electric Converter (AMTEC) and the Two-Phase Liquid Metal MHD Generator (LMMHD). This report describes progress that has been made during the first six months of 1992 on research activities associated with these two systems.

  4. Determination and verification of required water chemistry limits. Volume 4. Model boiler 5A tests. Research Project S111-1. Final report. [PWR

    Microsoft Academic Search

    J. E. Sireci; J. W. Klisiewicz

    1984-01-01

    The potential deleterious effects on steam generator materials of construction associated with the conversion from phosphate chemistry control to the now widely accepted All Volatile Treatment (AVT) method was evaluated in a model boiler test. The test initiated operation on phosphate chemistry and subsequently changed to AVT chemistry control and utilized a source of condenser cooling water which produces acidic

  5. A Detailed Chemical Kinetic Reaction Mechanism for n-Alkane Hydrocarbons from n-Octane to n-Hexadecane

    SciTech Connect

    Westbrook, C K; Pitz, W J; Herbinet, O; Silke, E J; Curran, H J

    2007-09-25

    Detailed chemical kinetic reaction mechanisms have been developed to describe the pyrolysis and oxidation of the n-alkanes, including n-octane (n-C{sub 8}H{sub 18}), n-nonane (n-C{sub 9}H{sub 20}), n-decane (n-C{sub 10}H{sub 22}), n-undecane (n-C{sub 11}H{sub 24}), n-dodecane (n-C{sub 12}H{sub 26}), n-tridecane (n-C{sub 13}H{sub 28}), n-tetradecane (n-C{sub 14}H{sub 30}), n-pentadecane (n-C{sub 15}H{sub 32}), and n-hexadecane (n-C{sub 16}H{sub 34}). These mechanisms include both high temperature and low temperature reaction pathways. The mechanisms are based on previous mechanisms for n-heptane, using the same reaction class mechanism construction developed initially for n-heptane. Individual reaction class rules are as simple as possible in order to focus on the parallelism between all of the n-alkane fuels included in the mechanisms, and there is an intent to develop these mechanisms further in the future to incorporate greater levels of accuracy and predictive capability. Several of these areas for improvement are identified and explained in detail. These mechanisms are validated through comparisons between computed and experimental data from as many different sources as possible. In addition, numerical experiments are carried out to examine features of n-alkane combustion in which the detailed mechanisms can be used to compare processes in all of the n-alkane fuels. The mechanisms for all of these n-alkanes are presented as a single detailed mechanism, which can be edited to produce efficient mechanisms for any of the n-alkanes included, and the entire mechanism, with supporting thermochemical and transport data, together with an explanatory glossary explaining notations and structural details, will be available on our web page when the paper is accepted for publication.

  6. A Detailed Chemical Kinetic Reaction Mechanism for n-Alkane Hydrocarbons From n-Octane to n-Hexadecane

    SciTech Connect

    Westbrook, C K; Pitz, W J; Herbinet, O; Curran, H J; Silke, E J

    2008-02-08

    Detailed chemical kinetic reaction mechanisms have been developed to describe the pyrolysis and oxidation of nine n-alkanes larger than n-heptane, including n-octane (n-C{sub 8}H{sub 18}), n-nonane (n-C{sub 9}H{sub 20}), n-decane (n-C{sub 10}H{sub 22}), n-undecane (n-C{sub 11}H{sub 24}), n-dodecane (n-C{sub 12}H{sub 26}), n-tridecane (n-C{sub 13}H{sub 28}), n-tetradecane (n-C{sub 14}H{sub 30}), n-pentadecane (n-C{sub 15}H{sub 32}), and n-hexadecane (n-C{sub 16}H{sub 34}). These mechanisms include both high temperature and low temperature reaction pathways. The mechanisms are based on our previous mechanisms for the primary reference fuels n-heptane and iso-octane, using the reaction class mechanism construction first developed for n-heptane. Individual reaction class rules are as simple as possible in order to focus on the parallelism between all of the n-alkane fuels included in the mechanisms, and these mechanisms will be refined further in the future to incorporate greater levels of accuracy and predictive capability. These mechanisms are validated through extensive comparisons between computed and experimental data from a wide variety of different sources. In addition, numerical experiments are carried out to examine features of n-alkane combustion in which the detailed mechanisms can be used to compare reactivities of different n-alkane fuels. The mechanisms for all of these n-alkanes are presented as a single detailed mechanism, which can be edited to produce efficient mechanisms for any of the n-alkanes included, and the entire mechanism, with supporting thermochemical and transport data, together with an explanatory glossary explaining notations and structural details, will be available for download from our web page.

  7. Perspective: What is known, and not known, about the connections between alkane oxidation and metal uptake in alkanotrophs in the marine environment

    PubMed Central

    Kenney, Grace E.; Rosenzweig, Amy C.

    2014-01-01

    Article Summary Should iron and copper be added to the environment to stimulate the natural bioremediation of marine oil spills? The key enzymes that catalyze the oxidation of alkanes require either iron or copper, and the concentration of these ions in seawater is vanishingly low. Nevertheless, the dependence of alkane oxidation activity on external metal concentrations remains unclear. This perspective will summarize what is known about the co-regulation of alkane oxidation and metal acquisition and pose a series of critical questions to which, for the most part, we do not yet have answers. The paucity of answers points to the need for additional studies to illuminate the cellular biology connecting microbial growth on alkanes to the acquisition of metal ions. PMID:24710692

  8. An analysis of organic matter sources for surface sediments in the central South Yellow Sea, China: evidence based on macroelements and n-alkanes.

    PubMed

    Zhang, Shengyin; Li, Shuanglin; Dong, Heping; Zhao, Qingfang; Lu, Xinchuan; Shi, Ji'an

    2014-11-15

    By analyzing the composition of n-alkane and macroelements in the surface sediments of the central South Yellow Sea of China, we evaluated the influencing factors on the distribution of organic matter. The analysis indicates that the distribution of total organic carbon (TOC) was low in the west and high in the east, and TOC was more related to Al2O3 content than medium diameter (MD). The composition of n-alkanes indicated the organic matter was mainly derived from terrestrial higher plants. Contributions from herbaceous plants and woody plants were comparable. The comprehensive analysis of the parameters of macroelements and n-alkanes showed the terrestrial organic matter in the central South Yellow Sea was mainly from the input of the modern Yellow River and old Yellow River. However, some samples exhibited evident input characteristics from petroleum sources, which changed the original n-alkanes of organic matter in sediments. PMID:25284443

  9. Density and viscosity of methanol-heptane (octane) mixtures at low alkane concentrations over the temperature range 288.15-328.15 K

    NASA Astrophysics Data System (ADS)

    Dyshin, A. A.; Eliseeva, O. V.; Kiselev, M. G.

    2012-04-01

    An Anton Paar 4500 densimeter was used to measure the density of methanol-heptane and methanol-octane solutions in the region of low alkane concentrations over the temperature range 288.15-328.15 K. The experimental data were used to calculate the apparent, partial, and excess molar volumes of alkanes. Viscosity was measured with an Ubbelohde viscometer at 298.15 K. The NMR spectra were recorded on a Bruker Avance III BioSpin spectrometer. The physicochemical characteristics of methanol-heptane and methanol-octane mixtures were considered in combination with molecular dynamics simulation results. The conclusion was drawn that methanol was structured in mixtures with heptane at concentrations of 0.04-0.06 alkane mole fractions. This peculiarity was not observed in mixtures with other alkanes.

  10. Teaching Conversation with Trivia.

    ERIC Educational Resources Information Center

    Crawford, Michael J.

    2002-01-01

    Presents a rationale for utilizing trivia to teach conversation. Shows how trivia-based materials fit into communicative language teaching approaches and provides examples of trivia-based activities and explains how to use them in the classroom. (Author/VWL)

  11. Economics of Grassland Conversion

    Technology Transfer Automated Retrieval System (TEKTRAN)

    In this paper we provide an overview of economic factors that contribute to changes in grassland area including the relative profitability of crop and livestock production, effects of land productivity, and effects of conversion costs. We also identify other potential socio-economic influences on gr...

  12. Our Digital Conversion

    ERIC Educational Resources Information Center

    Edwards, Mark

    2012-01-01

    In this article, the author describes their digital conversion initiative at Mooresville Graded School District. The project has placed a MacBook Air laptop in the hands of every 3rd through 12th grader and their teachers in the district over the past four years, with over 5,000 computers distributed. But they believe their academic successes have

  13. CONVERSATIONS ABOUT Colorectal Cancer

    E-print Network

    AGENDA CONVERSATIONS ABOUT Colorectal Cancer Saturday, March 8, 2014 9:30 a.m. - 12:30 p.m. FREE Medical Research Building 303 E. Superior, Chicago Hughes Auditorium Details and Registration: cancer.northwestern.edu/colorectal PUBLIC EVENT Colorectal patients and their families are invited to this free educational program hosted

  14. Clinical Linguistics: Conversational Reflections

    ERIC Educational Resources Information Center

    Crystal, David

    2013-01-01

    This is a report of the main points I made in an informal "conversation" with Paul Fletcher and the audience at the 14th ICPLA conference in Cork. The observations arose randomly, as part of an unstructured 1-h Q&A, so they do not provide a systematic account of the subject, but simply reflect the issues which were raised by the conference

  15. Metric to Inch Conversion

    Microsoft Academic Search

    W. M. Anderson; B. E. Robinson

    1964-01-01

    THE readers of the article by Mrs. Anderton and P. H. Bigg on `The Yard Unit of Length'1 may be interested in the results of an investigation following a discussion on metric to inch conversion. The definition of the yard, 0.9144 m exactly, legalized by the Weights and Measures Act, 1963, is equivalent to 1 in. = 25.4 mm exactly.

  16. A Conversation about Observation

    NASA Technical Reports Server (NTRS)

    Mather, John C.; Mao, Minnie Yuan

    2012-01-01

    In the spirit of the Lindau Meeting, we present a dialogue between a Nobel laureate and a young researcher. This interchange started online, where it continues to unfold. Here is a digest of this conversation, which has developed across time and space.

  17. Conversations and Collaborations

    ERIC Educational Resources Information Center

    Korpan, Cynthia

    2010-01-01

    This paper looks at how a series of conversations contributed to the development of a newly formed role at the University of Victoria--Teaching Assistant Consultants (TACs). TACs act as departmental mentors for teaching assistants (TAs) in their respective departments, charged with providing support in the form of discipline-specific workshops

  18. B.A. DEGREE REQUIREMENTS FOR CHEMISTRY (BIOLOGICAL CHEMISTRY TRACK)

    E-print Network

    Doyle, Robert

    326: Organic Chemistry Laboratory II (2) CHE 474: Structural and Physical Biochemistry I (3) 2: Intermediate Organic Chemistry (3) CHE 436: Advanced Physical Chemistry (3) CHE 467: Introduction to PhysicalB.A. DEGREE REQUIREMENTS FOR CHEMISTRY (BIOLOGICAL CHEMISTRY TRACK) Requirements include 21 credits

  19. Monte Carlo simulation of the adsorption of C2C7 linear alkanes in aluminophosphate AlPO4-11

    Microsoft Academic Search

    D. Zhang; Z. Liu; R. Xu

    2007-01-01

    The adsorption behaviors of linear alkanes ranging in length from C2 to C7 in AlPO4-11 have been simulated by using configurational-bias Monte Carlo technique at 313K. The calculated heats of adsorption at zero coverage for linear alkanes, estimated by Henry coefficients, are consistent well with previously reported experimental and simulation results. The simulated isotherms for n-hexane in AlPO4-11 at 298K

  20. Pseudomonas C12B, an SDS degrading strain, harbours a plasmid coding for degradation of medium chain length n-alkanes

    Microsoft Academic Search

    Jan Kostal; Miloslav Suchanek; Hana Klierova; Katerina Demnerova; Blanka Kralova; Dani L McBeth

    1998-01-01

    Pseudomonas C12B is able to degrade alkyl sulfates, alkylbenzene sulfonates, and linear alkanes and alkenes. Mitomycin C curing experiments and conjugation experiments demonstrated that the ability to utilize n-alkanes (C9C12) and n-alkenes (C10 and C12) of medium chain length was plasmid-encoded. The plasmid was designated pDEC. Its size was estimated at several hundreds kb according to mobility in agarose gels.

  1. Rapid analysis of 13C in plant-wax n-alkanes for reconstruction of terrestrial vegetation signals from aquatic sediments

    NASA Astrophysics Data System (ADS)

    McDuffee, Kelsey E.; Eglinton, Timothy I.; Sessions, Alex L.; Sylva, Sean; Wagner, Thomas; Hayes, John M.

    2004-10-01

    Long-chain, odd-carbon-numbered C25 to C35 n-alkanes are characteristic components of epicuticular waxes produced by terrestrial higher plants. They are delivered to aquatic systems via eolian and fluvial transport and are preserved in underlying sediments. The isotopic compositions of these products can serve as records of past vegetation. We have developed a rapid method for stable carbon isotopic analyses of total plant-wax n-alkanes using a novel, moving-wire system coupled to an isotope-ratio mass spectrometer (MW-irMS). The n-alkane fractions are prepared from sediment samples by (1) saponification and extraction with organic solvents, (2) chromatographic separation using silica gel, (3) isolation of straight-chain carbon skeletons using a zeolite molecular sieve, and (4) oxidation and removal of unsaturated hydrocarbons with RuO4. Short-chain n-alkanes of nonvascular plant origin (alkane fractions essentially free of interfering components. The ?13C values obtained by MW-irMS did not differ significantly from weighted averages of individual n-alkane ?13C values obtained by irmGC-MS. Isotopic variations in compound-class n-alkane fractions from a latitudinal transect of core-top sediments from the Southwest African margin (3N-28S) were congruent with those measured by compound-specific isotopic analyses of plant-wax n-alkanes. The amplitude of the variations was smaller, indicating contributions from non-plant-wax hydrocarbons, but the measurements revealed variations in carbon isotopic composition that are consistent with vegetation zones on the adjacent continent.

  2. Rapid analysis of 13C in plant-wax n-alkanes for reconstruction of terrestrial vegetation signals from aquatic sediments

    NASA Astrophysics Data System (ADS)

    McDuffee, Kelsey E.; Eglinton, Timothy I.; Sessions, Alex L.; Sylva, Sean; Wagner, Thomas; Hayes, John M.

    2004-10-01

    Long-chain, odd-carbon-numbered C25 to C35n-alkanes are characteristic components of epicuticular waxes produced by terrestrial higher plants. They are delivered to aquatic systems via eolian and fluvial transport and are preserved in underlying sediments. The isotopic compositions of these products can serve as records of past vegetation. We have developed a rapid method for stable carbon isotopic analyses of total plant-wax n-alkanes using a novel, moving-wire system coupled to an isotope-ratio mass spectrometer (MW-irMS). The n-alkane fractions are prepared from sediment samples by (1) saponification and extraction with organic solvents, (2) chromatographic separation using silica gel, (3) isolation of straight-chain carbon skeletons using a zeolite molecular sieve, and (4) oxidation and removal of unsaturated hydrocarbons with RuO4. Short-chain n-alkanes of nonvascular plant origin (alkane fractions essentially free of interfering components. The ?13C values obtained by MW-irMS did not differ significantly from weighted averages of individual n-alkane ?13C values obtained by irmGC-MS. Isotopic variations in compound-class n-alkane fractions from a latitudinal transect of core-top sediments from the Southwest African margin (3N-28S) were congruent with those measured by compound-specific isotopic analyses of plant-wax n-alkanes. The amplitude of the variations was smaller, indicating contributions from non-plant-wax hydrocarbons, but the measurements revealed variations in carbon isotopic composition that are consistent with vegetation zones on the adjacent continent.

  3. Magic size effect in the packing of n-alkanes on Au(1 1 1): evidence of lowered sliding force for molecules with specific length

    Microsoft Academic Search

    Alexandr Marchenko; Jacques Cousty

    2003-01-01

    Molecular structure of monolayers formed at the interface between Au(111) surfaces and solutions containing n-alkanes has been studied by in situ scanning tunneling microscopy at room temperature. Increasing the CnH2n+2 length from n=10 up to 50 with even n numbers alternates rectangular and tilted arrangement of alkanes within the self-organized layers. This alternation is related to the dramatically lowered sliding

  4. Development of an empirical force field CRACK for n-alkanes that allows for classical molecular dynamics simulations investigating the pyrolysis reactions

    Microsoft Academic Search

    Kailiang Yin; Qing Xia; Duanjun Xu; Yajing Ye; Chenglung Chen

    2006-01-01

    A novel empirical force field CRACK was developed for n-alkane that allowed for covalent bond breaking and forming, and can be used to investigate the pyrolysis of alkanes by classical molecular dynamics simulation (MD). The shape of CRACK potential-energy curve was for the pyrolysis reactions, with a deep harmonic well, an activation energy barrier and another shallow Lennard-Jones well. To

  5. Chemistry 365 Useful Information

    E-print Network

    Ronis, David M.

    Chemistry 365 Quiz II Useful Information kB = 1. 380662 10-23 J/K h = 6. 6256 10-27 erg sec how your expression changes if you were to use HD instead of H2. March 20, 2002 #12;Chemistry 365 -2.11 * From, G. W. Castellan, Physical Chemistry What would the order be in the high temperature limit? Why? 4

  6. Middle School Chemistry

    NSDL National Science Digital Library

    Middle school science resource from ACS. It includes activity-based lesson plans for teaching basic chemistry concepts that cover all the main concepts in middle school chemistry. Each lesson also contains integrated animations and video that a teacher can use to help explain student observations on the molecular level. Online professional development will also be available to introduce and familiarize teachers with the demonstrations, activities, and chemistry content in the site.

  7. Re-assessing the role of plant community change and climate in the PETM n-alkane record

    NASA Astrophysics Data System (ADS)

    Bush, R. T.; Baczynski, A. A.; McInerney, F. A.; Chen, D.

    2012-12-01

    The terrestrial leaf wax n-alkane record of the Paleocene-Eocene Thermal Maximum (PETM) in the Bighorn Basin, Wyoming, shows large excursions in both carbon isotope (?13C) values and n-alkane average chain length (ACL). At the onset of the PETM, ACL values increase from ~28.5 to ~30.1 while the negative carbon isotope excursion (CIE) is 4-6 in magnitude and larger than ?13C records from other materials. It has been hypothesized previously that both the ACL excursion and the large magnitude of the CIE were caused by a concurrent turnover in the local flora from a mixed conifer/angiosperm community before the PETM to a different suite of angiosperm species during the PETM. Here, we present the results of a meta-analysis of data (>2000 data from 89 sources, both published and unpublished) on n-alkane amounts and chain length distributions in modern plants from around the world. We applied the data in two sets of comparisons: 1) within and among plant groups such as herbs and graminoids, and 2) between plants and climate, using reported collection locations for outdoor plants and climate values generated via GIS extraction of WorldClim modeled data. We show that angiosperms, as group, produce more n-alkanes than do gymnosperms by 1-2 orders of magnitude, and this means that the gymnosperm contribution to a mixed soil n-alkane pool would be negligible, even in an ecosystem where gymnosperms dominated (i.e. the pre/post-PETM ecosystems). The modern plant data also demonstrate that turnover of the plant community during the PETM, even among only the angiosperm species, is likely not the source of the observed ACL excursion. First, we constructed "representative" groups of PETM and pre/post-PETM communities using living relative species at the Chicago Botanic Garden and find no significant difference in chain length distributions between the two groups. Second and moreover, the modern plant data reveal that n-alkane chain length distributions are tremendously variable within large vascular plant groups--both functional groups such as woody plants or graminoids as well as phylogenetic groups at the family level or higher. This variability makes it difficult at best to use n-alkane chain lengths to distinguish one vascular group from another, as was previously suggested. Instead, our results suggest that chain length distributions and ACL are driven more by climate, especially temperature. Longer chain lengths, with their increased hydrophobicity, would likely experience favorable selection under warmer or drier conditions where leaf water loss is likely to be a greater stress. Thus, it may be that we can interpret the increase in ACL during the PETM as a direct response by the flora to increased temperature during the hyperthermal event, and n-alkane chain length distributions, properly constrained, may possibly serve as a qualitative paleotemperature proxy.

  8. C22H46: the smallest open 3(1)-knotted alkane by computer-aided design.

    PubMed

    Krinas, Christos S; Demetropoulos, Ioannis N

    2008-04-01

    The program MolKnot [Chem. Phys. Lett. 433 (2007) 422-426] has been used in order to detect the smallest ever-reported alkane configured to an open-knotted shape with three crossings (3(1)). High level ab initio calculations support our findings that 22 carbon atoms are enough to create a knotted polyethylene strand with open ends. These tight open molecular knots exhibit unusually distorted geometric characteristics as multiple extended CC bonds (maximum bond length approximately 1.70A) and several large CCC bond angles (maximum bond angle approximately 145 degrees ). The energy decomposition shows that the strain mainly affects the valence angles of the entangled structure. We observed that this 22-knotted carbon atoms' region remained almost intact as a part of alkanes with longer chain lengths. PMID:18083597

  9. Synthesis, isolation and purification of C10-C13 polychloro-n-alkanes for use as standards in environmental analysis.

    PubMed

    Tomy, G T; Billeck, B; Stern, G A

    2000-03-01

    Short chain (C10-C13) polychloro-n-alkanes (sPCAs) mixtures were synthesized by refluxing pure n-alkane (> 99%) with sulfuryl chloride (SO2Cl2) in the presence of UV-light (550 W). The free radical initiated reactions produced analogs containing approximately 4-9 chlorine atoms on each carbon chain. Purification of reaction products was achieved by adsorption chromatography on Florisil. The products were characterized by high-resolution gas chromatography/mass spectrometry (HRGC/MS) operated in the electron capture negative ionization (ECNI) and in electron ionization (EI) modes. Individual standards can now be combined to create standards whose profiles resemble that of environmental samples. Quantification of a known amount of the newly synthesized sPCAs mixture, using an industrial formulation as an external standard, resulted in an overestimation (approximately 28%) in its true value. PMID:10705544

  10. Science Update: Analytical Chemistry.

    ERIC Educational Resources Information Center

    Worthy, Ward

    1980-01-01

    Briefly discusses new instrumentation in the field of analytical chemistry. Advances in liquid chromatography, photoacoustic spectroscopy, the use of lasers, and mass spectrometry are also discussed. (CS)

  11. The Chemistry of Cocaine

    NSDL National Science Digital Library

    Brahmadeo Dewprashad

    2010-01-01

    This case study on the chemistry of cocaine is in the form of a classroom discussion between a professor and her students about cocaine, its addictive properties, a search for an addiction treatment, and the chemistry involved in the synthesis of cocaine in its various forms. The case can be used to teach nucleophilic addition reactions, nucleophilic acyl substitution, and cocaine metabolism. In addition, it provides students with experience in locating, reading, and analyzing a research paper. The case was designed for the second course in a two-course sequence in undergraduate organic chemistry, but it could be adapted for medicinal chemistry classes.

  12. Saccharomyces cerevisiae SHSY detoxifies petroleum n-alkanes by an induced CYP52A58 and an enhanced order in cell surface hydrophobicity.

    PubMed

    Hanano, Abdulsamie; Shaban, Mouhnad; Almousally, Ibrahem; Al-Ktaifani, Mahmoud

    2015-09-01

    Environmental hydrocarbon contamination has a serious hazard to human health. Alkanes, the major component of hydrocarbons, can be consumed by various species of yeast. We previously identified a new strain SHSY of Saccharomyces cerevisiae with a remarkable ability to utilize the petroleum crude-oil (PCO) in aqueous solution. The current study demonstrated that the n-alkanes-assimilation activity of S. cerevisiae SHSY was related to an induced microsomal protein of 59kDa approximately. The identified ORF encoded a protein of 517 amino acids and shared 93% sequence identity with an alkane-inducible hydroxylase CYP52A53 isolated from Scheffersomyces stipitis CBS. It was therefore referred as CYP52A58. The catalytic activity of the recombinant CYP52A58 was confirmed by the hydroxylation of n-alkanes, it showed an optimal mono-terminal hydroxylation activity toward n-hexadecane. Moreover, the ability of the yeast to use n-alkanes was accompanied with an increasing level in cell wall mannoproteins. Two differential protein bands were detected in the mannoproteins extracted from PCO-grown yeast. In parallel, a significant increase in the fatty acids content with a high degree of unsaturation was subsequently detected in the PCO-grown yeast. This study characterizes a safe and potential microorganism to remove n-alkanes from the aquatic environment. PMID:25434275

  13. Leaf wax n-alkane ?D values of field-grown barley reflect leaf water ?D values at the time of leaf formation

    NASA Astrophysics Data System (ADS)

    Sachse, Dirk; Gleixner, Gerd; Wilkes, Heinz; Kahmen, Ansgar

    2010-12-01

    Leaf wax n-alkanes from barley ( Hordeum vulgare) from a field in Switzerland exhibited changes in ?D values on the order of 20 over a growing season, while source water (soil water) and leaf water varied by 40. Additionally the seasonal variability in ?D values of leaf wax n-alkanes of different barley leaves can only be found across different leaf generations (i.e. leaves that were produced at different times during the growing season) while n-alkane ?D values did not vary significantly within a leaf generation. Interestingly, ?D values of n-alkanes correlated best with the ?D values of leaf water at midday of the sampling day but showed no significant correlation with soil water (e.g. precipitation) ?D values. These results provide empirical evidence that leaf wax ?D values record leaf water enrichment, and therefore integrate the isotopic effects of precipitation and evapotranspiration. Our results show that leaf wax n-alkane ?D values from grasses are 'locked in' early during leaf development and hence record the environmental drivers of leaf water enrichment, such as vapor pressure deficit (VPD). Our data have important implications for the interpretation of paleorecords of leaf wax ?D. We suggest that leaf wax n-alkane ?D values from sedimentary records could be used to estimate changes in the degree of leaf water enrichment and hence VPD.

  14. Involvement of acyl-CoA synthetase genes in n-alkane assimilation and fatty acid utilization in yeast Yarrowia lipolytica.

    PubMed

    Tenagy; Park, Jun Seok; Iwama, Ryo; Kobayashi, Satoshi; Ohta, Akinori; Horiuchi, Hiroyuki; Fukuda, Ryouichi

    2015-06-01

    Here, we investigated the roles of YAL1 (FAA1) and FAT1 encoding acyl-CoA synthetases (ACSs) and three additional orthologs of ACS genes FAT2-FAT4 of the yeast Yarrowia lipolytica in the assimilation or utilization of n-alkanes and fatty acids. ACS deletion mutants were generated to characterize their function. The FAT1 deletion mutant exhibited decreased growth on n-alkanes of 10-18 carbons, whereas the FAA1 mutant showed growth reduction on n-alkane of 16 carbons. However, FAT2-FAT4 deletion mutants did not show any growth defects, suggesting that FAT1 and FAA1 are involved in the activation of fatty acids produced during the metabolism of n-alkanes. In contrast, deletions of FAA1 and FAT1-FAT4 conferred no defect in growth on fatty acids. The wild-type strain grew in the presence of cerulenin, an inhibitor of fatty acid synthesis, by utilizing exogenously added fatty acid or fatty acid derived from n-alkane when oleic acid or n-alkane of 18 carbons was supplemented. However, the FAA1 deletion mutant did not grow, indicating a critical role for FAA1 in the utilization of fatty acids. Fluorescent microscopic observation and biochemical analyses suggested that Fat1p is present in the peroxisome and Faa1p is localized in the cytosol and to membranes. PMID:26019148

  15. Phosphatidic acid and phosphoinositides facilitate liposome association of Yas3p and potentiate derepression of ARE1 (alkane-responsive element one)-mediated transcription control.

    PubMed

    Kobayashi, Satoshi; Hirakawa, Kiyoshi; Horiuchi, Hiroyuki; Fukuda, Ryouichi; Ohta, Akinori

    2013-12-01

    In the n-alkane assimilating yeast Yarrowia lipolytica, the expression of ALK1, encoding a cytochrome P450 that catalyzes terminal mono-oxygenation of n-alkanes, is induced by n-alkanes. The transcription of ALK1 is regulated by a heterocomplex that comprises the basic helix-loop-helix transcription activators, Yas1p and Yas2p, and binds to alkane-responsive element 1 (ARE1) in the ALK1 promoter. An Opi1 family transcription repressor, Yas3p, represses transcription by binding to Yas2p. Yas3p localizes in the nucleus when Y. lipolytica is grown on glucose but localizes to the endoplasmic reticulum (ER) upon the addition of n-alkanes. In this study, we showed that recombinant Yas3p binds to the acidic phospholipids, phosphatidic acid (PA) and phosphoinositides (PIPs), in vitro. The ARE1-mediated transcription was enhanced in vivo in mutants defective in an ortholog of the Saccharomyces cerevisiae gene PAH1, encoding PA phosphatase, and in an ortholog of SAC1, encoding PIP phosphatase in the ER. Truncation mutation analyses for Yas3p revealed two regions that bound to PA and PIPs. These results suggest that the interaction with acidic phospholipids is important for the n-alkane-induced association of Yas3p with the ER membrane. PMID:24120453

  16. BachelorofScience/BachelorofEducation Chemistry/ScienceEducation

    E-print Network

    Morris, Joy

    - Organic Chemistry II ___ 6. Chemistry 2740 - Physical Chemistry List B - Elective Chemistry - Contemporary Chemistry ___Chemistry 3410 - Analytical Chemistry II ___Chemistry 3730 - Advanced PhysicalBachelorofScience/BachelorofEducation Chemistry/ScienceEducation This is a planning guide

  17. Hydroconversion of C 5C 8 alkanes over Zr-containing supported catalysts prepared by metal vapor method

    Microsoft Academic Search

    Vagif M Akhmedov; Soliman H Al-Khowaiter; Jamal K Al-Refai

    2003-01-01

    Zr-containing supported catalysts (Zr\\/ZSM-5, Zr-Re\\/ZSM-5 and Zr-Ni\\/ZSM-5) were prepared by metal vapor method (MVM). The isomerization and cracking activity and selectivity of prepared catalysts were investigated in hydroconversion of n-C5C8 alkanes. Results have shown that activity and selectivity of bimetallic catalysts toward hydroconversion of tested hydrocarbons were much higher than those over monometallic Zr\\/ZSM-5. The most significant difference was observed

  18. Use of sodium dodecyl sulphate for stimulation of biodegradation of n-alkanes without residual contamination by the surfactant

    Microsoft Academic Search

    Miloslav Suchanek; Jan Kostal; Katerina Demnerova; Blanka Kralova

    2000-01-01

    The capacity of a range of aliphatic alkanes (C6C16), intermediates of n-decane oxidation and sodium dodecyl sulphate (SDS) to induce decane-mineralization activity in the cells of Pseudomonas C12B was compared with that for n-decane. The comparison on quantitative basis had two serious limitations: low solubility of tested inducers in aqueous solutions and their toxicity to bacterial cells. Carbon chain length

  19. Phase Separation in the Organic Solid State: The Influence of Quenching Protocol in Unstable n-Alkane Blends

    Microsoft Academic Search

    E. P. Gilbert; A. Nelson; D. Sutton; N. Terrill; C. Martin; J. Lal; E. Lang; Bragg Inst

    2005-01-01

    Blends of normal alkanes form lamellar structures, when quenched from the melt, in which the separation of the individual chains may be controlled by the chain-length mismatch, molar composition, isotopic substitution and confinement. 2:1 C28H58:C36D74 mixtures have been investigated after subjection to a cooling rate varying over three orders of magnitude and intermediate annealing prior to reaching ambient. Quenching at

  20. Long-chain (C 19C 29) 1-chloro- n-alkanes in leaf waxes of halophytes of the Chenopodiaceae

    Microsoft Academic Search

    Vincent Grossi; Danielle Raphel

    2003-01-01

    The hydrocarbon fraction of leaf waxes of three halophytes of the Chenopodiaceae common to Mediterranean salt marshes (Suaeda vera, Sarcocornia fruticosa and Halimione portulacoides) revealed the presence of a minor series of odd and even chains 1-chloro-n-alkanes ranging from C19 to C29. The identification of these new chlorinated plant constituents was based on a combination of mass spectrometry data with

  1. Diverse sulfate-reducing bacteria of the Desulfosarcina/Desulfococcus clade are the key alkane degraders at marine seeps.

    PubMed

    Kleindienst, Sara; Herbst, Florian-Alexander; Stagars, Marion; von Netzer, Frederick; von Bergen, Martin; Seifert, Jana; Peplies, Jrg; Amann, Rudolf; Musat, Florin; Lueders, Tillmann; Knittel, Katrin

    2014-10-01

    Biogeochemical and microbiological data indicate that the anaerobic oxidation of non-methane hydrocarbons by sulfate-reducing bacteria (SRB) has an important role in carbon and sulfur cycling at marine seeps. Yet, little is known about the bacterial hydrocarbon degraders active in situ. Here, we provide the link between previous biogeochemical measurements and the cultivation of degraders by direct identification of SRB responsible for butane and dodecane degradation in complex on-site microbiota. Two contrasting seep sediments from Mediterranean Amon mud volcano and Guaymas Basin (Gulf of California) were incubated with (13)C-labeled butane or dodecane under sulfate-reducing conditions and analyzed via complementary stable isotope probing (SIP) techniques. Using DNA- and rRNA-SIP, we identified four specialized clades of alkane oxidizers within Desulfobacteraceae to be distinctively active in oxidation of short- and long-chain alkanes. All clades belong to the Desulfosarcina/Desulfococcus (DSS) clade, substantiating the crucial role of these bacteria in anaerobic hydrocarbon degradation at marine seeps. The identification of key enzymes of anaerobic alkane degradation, subsequent ?-oxidation and the reverse Wood-Ljungdahl pathway for complete substrate oxidation by protein-SIP further corroborated the importance of the DSS clade and indicated that biochemical pathways, analog to those discovered in the laboratory, are of great relevance for natural settings. The high diversity within identified subclades together with their capability to initiate alkane degradation and growth within days to weeks after substrate amendment suggest an overlooked potential of marine benthic microbiota to react to natural changes in seepage, as well as to massive hydrocarbon input, for example, as encountered during anthropogenic oil spills. PMID:24722631

  2. Biotransformation of medium-chain alkanes using recombinant P450 monooxygenase from Alcanivorax borkumensis SK2 expressed in Escherichia coli

    Microsoft Academic Search

    Sang-Ho Baik

    2010-01-01

    A bioconversion system for medium-chain alkanes was constructed by using a recombinant Escherichia coli whole-cell biocatalyst expressing P450 monooxygenase genes, ferredoxin, and ferredoxin reductase cloned from Alcanivorax borkumensis as an operon. The recombinant E. coli harboring the P450 gene and two related expression component enzymes, ferredoxin and ferredoxin reductase, was constructed\\u000a in a single vector pET21(a) and successfully expressed in

  3. EVALUATION OF THE HEAT OF ADSORPTION OF SOME n-ALKANES ON ALUMINA AND ZEOLITE BY INVERSE GAS CHROMATOGRAPHY

    Microsoft Academic Search

    Ay?egl A?kin

    2001-01-01

    The isosteric heat of adsorption of some n-alkanes (n-C5 to n-C8) on some adsorbents(activated alumina, natural zeolite(clinoptilolite) and 13X molecular sieve) were evaluated by inverse gas chromatography using the temperature dependence of adsorption.The isosteric heat of adsorption of the probes on alumina and clinoptilolite were determined in the finite concentration region, and those on 13X were determined in the infinite

  4. Accumulation and depuration of sediment-sorbed C- and C-polychlorinated alkanes by oligochaetes (Lumbriculus variegatus)

    Microsoft Academic Search

    Aaron T. Fisk; Susanna C. Wiens; G. R. Barrie Webster; A. Bergman; Derek C. G. Muir

    1998-01-01

    Oligochaetes (Lumbriculus variegatus) were exposed to sediment spiked with four ¹⁴C-polychlorinated alkanes (PCAs) (CHCl [56% Cl by weight], CHCl [69% Cl], CHCl [35% Cl], and CHCl [69% Cl]) to measure bioaccumulation parameters and biotransformation. Chlorinated paraffins are industrial products that consist of thousands of different PCAs. Chlorinated paraffins are hydrophobic and are reported to have relatively high concentrations in sediment

  5. Experimental and Computational Study of Flame Inhibition Mechanisms of Halogenated Compounds in C1-C3 Alkanes Flames

    E-print Network

    Osorio Amado, Carmen H

    2013-07-30

    EXPERIMENTAL AND COMPUTATIONAL STUDY OF FLAME INHIBITION MECHANISMS OF HALOGENATED COMPOUNDS IN C1-C3 ALKANES FLAMES A Dissertation by CARMEN HELENA OSORIO AMADO Submitted to the Office of Graduate Studies of Texas A&M University... Chair, Ibrahim Karaman August 2013 Major Subject: Materials Science and Engineering Copyright 2013 Carmen Helena Osorio Amado ii ABSTRACT After the restriction of different halogenated fire suppressants by the Montreal Protocol...

  6. Numerical modeling of isolated n-alkane droplet flames: initial comparisons with ground and space-based microgravity experiments

    Microsoft Academic Search

    Anthony J. Marchese; Frederick L. Dryer; Vedha Nayagam

    1999-01-01

    Transient, spherically symmetric, combustion of single and multi-component liquid n-alkane droplets is numerically simulated with a model that includes gas phase detailed, multi-component molecular transport and complex chemical kinetics. A compact semi-detailed kinetic mechanism for n-heptane and n-hexadecane oxidation consisting of 51 species (including He, Ar, and N2) and 282 reactions is used to describe the gas phase. Non-luminous, gas

  7. The effects of solvent mixtures on the gel permeation chromatography of alkanes, fatty acids, and fatty acid esters

    E-print Network

    Bolton, Patrick Lee

    1985-01-01

    -alkanes, fatty acids, and methyl and butyl fatty acid esters were separated on a crosslinked polystyrene- divinylbenzene column in mixtures of THF with 1, 4-dioxane, toluene, benzene, acetone, methyl ethyl ketone, and o-dichlorobenzene. A sample of phenolic... in the preparation of this thesis. vi TABLE OF CONTENTS CHAPTER Page I INTRODUCTION Gel Permeation Chromatography of Small Molecules Objectives 1 4 II REVIEW OF LITERATURE GPC of Small Molecules, Current Research GPC, Solvent Mixtures 6 8 III MATERIALS...

  8. Re-evaluating the isotopic divide between angiosperms and gymnosperms using n-alkane ?13C values

    NASA Astrophysics Data System (ADS)

    Bush, R. T.; McInerney, F. A.

    2009-12-01

    Angiosperm ?13C values are typically 1-3 more negative than those of co-occurring gymnosperms. This is known for both bulk leaf and compound-specific values from n-alkanes, which are stable, straight-chain hydrocarbons (C23-C35) found in the epicuticular leaf wax of vascular plants. For n-alkanes, there is a second distinction between the ?13C values of angiosperms and gymnosperms?13C values generally decrease with increasing chain-length in angiosperms, while in gymnosperms they increase. These two distinctions have been used to support the plant community change hypothesis explaining the difference between the terrestrial and marine carbon isotope excursions during the Paleocene-Eocene Thermal Maximum (PETM.) Preserved n-alkanes from terrestrial paleosols in the Bighorn Basin, Wyoming reveal a negative carbon isotope excursion during the PETM of 4-5, which is 1-2 greater than the excursion recorded by marine carbonates. The local plant community, known from macrofossils as well as palynoflora, shifted from a deciduous, mixed angiosperm/gymnosperm flora to a suite of evergreen angiosperm species during the PETM. At the end of the PETM, the community returned to a mixed deciduous flora very similar to the original. This change in the plant community could thus magnify the terrestrial negative carbon isotope excursion to the degree necessary to explain its divergence from the marine record. However, the comparison between modern angiosperms and gymnosperms has been made mostly between broadleaf, deciduous angiosperms and evergreen, coniferous gymnosperms. New data analyzing deciduous, coniferous gymnosperms, including Metasequoia glyptostroboides and Taxodium distichum, suggests that the division previously ascribed to taxonomy may actually be based on leaf habit and physiology, specifically broadleaf, deciduous versus needle-leaf, evergreen plants. If differences in n-alkane ?13C values can be described not as angiosperms versus gymnosperms, but as deciduous versus evergreen plants, then a re-examination of the PETM terrestrial carbon isotope excursion and its causes may be necessary.

  9. Low energy carbon ion bombardment on indium phosphide and its implications for alkane-based reactive ion etching

    Microsoft Academic Search

    P. F. A. Meharg; E. A. Ogryzlo; I. Bello; W. M. Lau

    1992-01-01

    Carbon ion bombardment in the energy range of 20500 eV, which occurs in reactive ion etching using alkanes, has been performed on InP with a mass-separated carbon ion beam in an ultrahigh vacuum chamber. The sample structure consisted of an ultrathin, epitaxial InP (40 A?) layer on InGaAs. Insitu polar-angle dependent x-ray photoelectron spectroscopy was used to measure sputtering, deposition

  10. Kinetics of the hydrogen abstraction CHO + Alkane ? HCHO + Alkyl reaction class: an application of the reaction class transition state theory

    Microsoft Academic Search

    Lam K. Huynh; Thanh N. Truong

    2008-01-01

    The kinetics of the hydrogen abstraction at alkanes by formyl radicals is investigated using the reaction class transition\\u000a state theory (RC-TST) approach combined with the linear energy relationship (LER) or the barrier height grouping (BHG). The\\u000a rate constants of a reaction in this class can be estimated through those of the reference reaction, CHO + C2H6, which are obtained from

  11. Sterol and n-alkane biomarker composition of modern fen plants - potential application for palaeoecological analyses

    NASA Astrophysics Data System (ADS)

    Ronkainen, T.; McClymont, E. L.; Vliranta, M.; Tuittila, E.

    2011-12-01

    Acute and contemporary questions related to human-induced changes in climate have emphasized the importance of peatland research because peatlands store large quantities of carbon. Historically, pristine mires have been long-term sinks for atmospheric carbon because of a slow decomposition rate of the organic matter once below the water table. However, the net carbon balance of mires is highly sensitive and reflects changes in moisture conditions and consequent changes in vegetation assemblages. Historical variations in climate and hydrology are recorded in peat layers as alteration in the assemblages of different biological organisms. Past vegetation assemblages are in a key role when reconstructing the past moisture conditions that control peatland carbon dynamics. In order to evaluate the role of northern peatlands as carbon sinks or sources in changing future climate, it is important to understand the past mechanisms: how mires have earlier responded to climate forcing. An especially useful proxy method to reconstruct past environmental changes is the plant macrofossil method. Large parts of northern peatlands are fens, where, as a result of fast surface decay, major parts of the peat below the surface layer is highly humified. Bog peats, in turn, usually contain relatively well preserved plant material for palaeoecological examination, but highly humified layers can also be found underneath the top layers of bog peats. A high degree of humification constrains palaeo-botanical and -climatical studies because reliable identification of different fossil vegetation components is difficult. Previous work has shown that plant biomarkers (compounds that can be linked to specific plant types) can be successfully applied to indentify modern and fossil plant groups from less-humified bog peat. In this study we apply selected organic geochemistry methods to fen plant species to investigate the potential for biomarkers to characterise different fen plants. We focus on plant types that would give insight into major palaeoecological challenges (e.g. Sphagnum subsecundum, Warnstorfia exannulata, Carex livida). We report n-alkane and sterol distributions and concentrations in shoots, stems and roots from 12 plant species common to fens. The primary results are promising, confirming some previously established relationships in peat-forming plants e.g. n-alkane chain length differs between the main plant types (e.g. Sphagnum versus non-Sphagnum). However, we also find that biomarker composition, and thus interpretation of the chemical fingerprints of fen plants, is not as straightforward as in bog plants. The implications of these results for palaeo-ecological investigations are discussed.

  12. Nitroxide spin exchange due to re-encounter collisions in a series of n-alkanes.

    PubMed

    Kurban, Mark R; Peric, Miroslav; Bales, Barney L

    2008-08-14

    Bimolecular collisions between perdeuterated 2,2,6,6-tetramethyl-4-oxopiperidine-l-oxyl molecules in three alkanes have been studied by measuring the electron paramagnetic resonance (EPR) spectral changes induced by spin exchange. We define an "encounter" to be a first-time collision followed by a series of re-encounters prior to the diffusing pair's escaping each other's presence. The present work stems from a recent proposal [B. L. Bales et al., J. Phys. Chem. A 107, 9086 (2003)] that an unexpected linear dependence of the spin-exchange-induced EPR line shifts on spin-exchange frequency can be explained by re-encounters of the same probe pair during one encounter. By employing nonlinear least-squares fitting, full use of the information available from the spectral changes allows us to study encounters and re-encounters separately. The encounter rate constants appear to be dominated by hydrodynamic forces, forming a common curve for hexane, decane, and hexadecane when plotted against T/eta, where eta is the shear viscosity. Unexpectedly, encounters are not dependent on the ratio mu = a/a(s), where a and a(s) are the van der Waals radii of the nitroxide probe and the solvent, respectively. It is argued that the near coincidence of the resulting encounter rate constant with the hydrodynamic prediction is likely due to a near cancellation of terms in the general diffusion coefficient. Thus, the semblance of hydrodynamic behavior is coincidental rather than intrinsic. In contrast, the mean times between re-encounters do depend on the relative sizes of probe and solvent. For hexane at lower temperatures, the Stokes-Einstein equation apparently describes re-encounters well; however, at higher temperatures and for decane and hexadecane, departures from the hydrodynamic prediction become larger as mu becomes smaller. This is in qualitative agreement with the theory of microscopic diffusion of Hynes et al. [J. Chem. Phys. 70, 1456 (1979)]. These departures are well correlated with the free volume available in the solvent; thus, the mean times between re-encounters form a common curve when plotted versus the free volume. Because free volume is manifested macroscopically by the isothermal compressibility, it is expected and observed that the re-encounter rate also forms a common curve across all three solvents when plotted with respect to compressibility. The existence of a common curve for alkanes raises the prospect of using EPR to determine the compressibility of substances such as fossil fuels and biological membranes. PMID:18715079

  13. Engineering an iterative polyketide pathway in Escherichia coli results in single-form alkene and alkane overproduction.

    PubMed

    Liu, Qian; Wu, Kaiyue; Cheng, Yongbo; Lu, Lei; Xiao, Erting; Zhang, Yuchen; Deng, Zixin; Liu, Tiangang

    2015-03-01

    Alkanes and alkenes are ideal biofuels, due to their high energy content and ability to be safely transported. To date, fatty acid-derived pathways for alkane and alkene bioproduction have been thoroughly explored. In this study, we engineered the pathway of the iterative Type I polyketide synthase (PKS) SgcE with the cognate thioesterase (TE) SgcE10 in Escherichia coli, with the goal of overproducing pentadecaheptaene (PDH) followed by its hydrogenation to pentadecane (PD). Based on initial in vitro titration assays, we learned that PDH production is strongly dependent on the SgcE10:SgcE ratio. Thus, we engineered a high-yield E. coli strain by fine-tuning SgcE10 expression via synthetic promoters. We analyzed engineered E. coli strains using a modified multiple reactions monitoring mass spectrometry (MRM-MS)-based targeted proteomic approach, using a chimeric SgcE10 and SgcE fusion construct to gain insight into expression levels of the two proteins. Lastly, through fed-batch fermentation followed by flow chemical hydrogenation, we obtained a PD yield of nearly 140mg/L in single-alkane form. Thus, we not only employed a metabolic engineering approach to the iterative polyketide pathway, we highlighted the potential of PKS shunt products to play a role in the production of single-form and high-value chemicals. PMID:25536488

  14. General Chemistry I Digital Lecture Material

    NSDL National Science Digital Library

    Ott, Mark

    Dr. Mark Ott, a professor at Jackson Community College in Wyoming, has created a set of compelling screencasts and accompanying audio tracks that are designed to complement his general chemistry lectures. Visitors can look over these materials at their leisure, and they will find very well-thought out lessons that cover such topics as unit conversion, molecular formulae, balancing chemical equations, and ionic and covalent bonding. All of these materials are lucid and might be used both by students who are becoming more acquainted with the world of chemistry, or by educators who might be seeking to assist their students in the learning process. These learning modules are available here in either the Flash format or via Google video.

  15. Photoelectrochemical solar energy conversion

    NASA Astrophysics Data System (ADS)

    Memming, Rdiger

    In the present paper the progress in the field of solar energy conversion for the production of electricity and storable chemical fuels during the last decade is reviewed. The current-potential behavior of regenerative photovoltaic cells are derived and related to charge transfer processes at the solid/liquid interface. Various cells are critically analyzed in view of their stability and conversion efficiency. A number of factors limiting the photovoltage are discussed in terms of a stabilization mechanism, trapping of minority carriers at the interface and the forward dark current. Concerning the production of chemical fuels the photocleavage of water and hydrogen sulfide, the reduction of carbon dioxide and the formation of ammonia is evaluated. The main emphasis is laid here on catalytic processes at semiconductor electrodes and particles. The principle function of catalysts being deposited on extended electrodes and particles are discussed in detail.

  16. Frequency conversion system

    NASA Technical Reports Server (NTRS)

    Sanders, Steven (Inventor); Lang, Robert J. (Inventor)

    2001-01-01

    Laser diode pumped mid-IR wavelength sources include at least one high power, near-IR wavelength, injection and/or sources wherein one or both of such sources may be tunable providing a pump wave output beam to a quasi-phase matched (QPM) nonlinear frequency mixing (NFM) device. The NFM device may be a difference frequency mixing (DFM) device or an optical parametric oscillation (OPO) device. Wavelength tuning of at least one of the sources advantageously provides the ability for optimizing pump or injection wavelengths to match the QPM properties of the NFM device enabling a broad range of mid-IR wavelength selectivity. Also, pump powers are gain enhanced by the addition of a rare earth amplifier or oscillator, or a Raman/Brillouin amplifier or oscillator between the high power source and the NFM device. Further, polarization conversion using Raman or Brillouin wavelength shifting is provided to optimize frequency conversion efficiency in the NFM device.

  17. Introduction to Solar Photon Conversion

    SciTech Connect

    Nozik, A.; Miller, J.

    2010-11-10

    The efficient and cost-effective direct conversion of solar photons into solar electricity and solar fuels is one of the most important scientific and technological challenges of this century. It is estimated that at least 20 terawatts of carbon-free energy (1 and 1/2 times the total amount of all forms of energy consumed today globally), in the form of electricity and liquid and gaseous fuels, will be required by 2050 in order to avoid the most serious consequences of global climate change and to ensure adequate global energy supply that will avoid economic chaos. But in order for solar energy to contribute a major fraction of future carbon-free energy supplies, it must be priced competitively with, or perhaps even be less costly than, energy from fossil fuels and nuclear power as well as other renewable energy resources. The challenge of delivering very low-cost solar fuels and electricity will require groundbreaking advances in both fundamental and applied science. This Thematic Issue on Solar Photon Conversion will provide a review by leading researchers on the present status and prognosis of the science and technology of direct solar photoconversion to electricity and fuels. The topics covered include advanced and novel concepts for low-cost photovoltaic (PV) energy based on chemistry (dye-sensitized photoelectrodes, organic and molecular PV, multiple exciton generation in quantum dots, singlet fission), solar water splitting, redox catalysis for water oxidation and reduction, the role of nanoscience and nanocrystals in solar photoconversion, photoelectrochemical energy conversion, and photoinduced electron transfer. The direct conversion of solar photons to electricity via photovoltaic (PV) cells is a vital present-day commercial industry, with PV module production growing at about 75%/year over the past 3 years. However, the total installed yearly averaged energy capacity at the end of 2009 was about 7 GW-year (0.2% of global electricity usage). Thus, there is potential for the PV industry to grow enormously in the future (by factors of 100-300) in order for it to provide a significant fraction of total global electricity needs (currently about 3.5 TW). Such growth will be greatly facilitated by, and probably even require, major advances in the conversion efficiency and cost reduction for PV cells and modules; such advances will depend upon advances in PV science and technology, and these approaches are discussed in this Thematic Issue. Industrial and domestic electricity utilization accounts for only about 30% of the total energy consumed globally. Most ({approx}70%) of our energy consumption is in the form of liquid and gaseous fuels. Presently, solar-derived fuels are produced from biomass (labeled as biofuels) and are generated through biological photosynthesis. The global production of liquid biofuels in 2009 was about 1.6 million barrels/day, equivalent to a yearly output of about 2.5 EJ (about 1.3% of global liquid fuel utilization). The direct conversion of solar photons to fuels produces high-energy chemical products that are labeled as solar fuels; these can be produced through nonbiological approaches, generally called artificial photosynthesis. The feedstocks for artificial photosynthesis are H{sub 2}O and CO{sub 2}, either reacting as coupled oxidation-reduction reactions, as in biological photosynthesis, or by first splitting H{sub 2}O into H{sub 2} and O{sub 2} and then reacting the solar H{sub 2} with CO{sub 2} (or CO produced from CO2) in a second step to produce fuels through various well-known chemical routes involving syngas, water gas shift, and alcohol synthesis; in some applications, the generated solar H{sub 2} itself can be used as an excellent gaseous fuel, for example, in fuel cells. But at the present time, there is no solar fuels industry. Much research and development are required to create a solar fuels industry, and this Thematic Issue presents several reviews on the relevant solar fuels science and technology. The first three manuscripts relate to the daunting problem of producing

  18. Energy-mass conversion

    NSDL National Science Digital Library

    Lawrence Berkeley National Laboratory. Particle Data Group

    2002-01-01

    How do physicists make new particles? In this page of a particle physics tutorial, students are introduced to the concept of converting kinetic energy to mass. Students read that low-mass particles placed into an accelerator can be smashed together to produce more massive particles through the conversion of energy to mass. They see an example in which two pieces of fruit are accelerated and smashed, and additional types of fruit are produced. Copyright 2005 Eisenhower National Clearinghouse

  19. Refining Conversational Case Libraries

    Microsoft Academic Search

    David W. Aha; Leonard Breslow

    1997-01-01

    . Conversational case-based reasoning (CBR) shells (e.g., Inference's CBR Express) are commercially successful tools for supportingthe development of help desk and related applications. In contrast torule-based expert systems, they capture knowledge as cases rather thanmore problematic rules, and they can be incrementally extended. However,rather than eliminate the knowledge engineering bottleneck, theyrefocus it on case engineering, the task of carefully authoring

  20. Pyroelectric conversion in space

    NASA Technical Reports Server (NTRS)

    Olsen, R. B.

    1984-01-01

    Pyroelectric conversion in space deserves a close look as preliminary calculations indicate that a system specific power of 350 to 850 watts per kilogram will be feasible. This power-to-weight ratio far exceeds state-of-the-art photovoltaic systems (40 to 66 watts/kg) and surpasses proposed thin blanket photovoltaics (about 300 watts/kg). In addition to its high specific power, the pyroelectric approach promises to be far less expensive than photovoltaics.