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1

Atmospheric chemistry of alkanes  

Microsoft Academic Search

The reactions of the alkanes under atmospheric conditions and in the presence of oxides of nitrogen are reviewed and evaluated. Particular emphasis is placed upon their subsequent reactions after the initial OH radical reaction under conditions where the alkyl peroxy radicals produced react predominantly with NO, rather than with HO2 and\\/or RO2 radicals. Methods are discussed for estimating the overall

William P. L. Carter; Roger Atkinson

1985-01-01

2

Catalytic conversion of light alkanes  

SciTech Connect

The second Quarterly Report of 1992 on the Catalytic Conversion of Light Alkanes reviews the work done between April 1, 1992 and June 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 that can either be used as clean-burning, high octane liquid fuels, as fuel components or as precursors to liquid hydrocarbon uwspomdon 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 regular oxidic lattices including zeolites and related structures as well as other molecular surface structures having metal oxo groups (PHASE I).

Lyons, J.E.

1992-06-30

3

Alkane metathesis by tandem alkane-dehydrogenation-olefin-metathesis catalysis and related chemistry.  

PubMed

Methods for the conversion of both renewable and non-petroleum fossil carbon sources to transportation fuels that are both efficient and economically viable could greatly enhance global security and prosperity. Currently, the major route to convert natural gas and coal to liquids is Fischer-Tropsch catalysis, which is potentially applicable to any source of synthesis gas including biomass and nonconventional fossil carbon sources. The major desired products of Fischer-Tropsch catalysis are n-alkanes that contain 9-19 carbons; they comprise a clean-burning and high combustion quality diesel, jet, and marine fuel. However, Fischer-Tropsch catalysis also results in significant yields of the much less valuable C(3) to C(8)n-alkanes; these are also present in large quantities in oil and gas reserves (natural gas liquids) and can be produced from the direct reduction of carbohydrates. Therefore, methods that could disproportionate medium-weight (C(3)-C(8)) n-alkanes into heavy and light n-alkanes offer great potential value as global demand for fuel increases and petroleum reserves decrease. This Account describes systems that we have developed for alkane metathesis based on the tandem operation of catalysts for alkane dehydrogenation and olefin metathesis. As dehydrogenation catalysts, we used pincer-ligated iridium complexes, and we initially investigated Schrock-type Mo or W alkylidene complexes as olefin metathesis catalysts. The interoperability of the catalysts typically represents a major challenge in tandem catalysis. In our systems, the rate of alkane dehydrogenation generally limits the overall reaction rate, whereas the lifetime of the alkylidene complexes at the relatively high temperatures required to obtain practical dehydrogenation rates (ca. 125 -200 °C) limits the total turnover numbers. Accordingly, we have focused on the development and use of more active dehydrogenation catalysts and more stable olefin-metathesis catalysts. We have used thermally stable solid metal oxides as the olefin-metathesis catalysts. Both the pincer complexes and the alkylidene complexes have been supported on alumina via adsorption through basic para-substituents. This process does not significantly affect catalyst activity, and in some cases it increases both the catalyst lifetime and the compatibility of the co-catalysts. These molecular catalysts are the first systems that effect alkane metathesis with molecular-weight selectivity, particularly for the conversion of C(n)n-alkanes to C(2n-2)n-alkanes plus ethane. This molecular-weight selectivity offers a critical advantage over the few previously reported alkane metathesis systems. We have studied the factors that determine molecular-weight selectivity in depth, including the isomerization of the olefinic intermediates and the regioselectivity of the pincer-iridium catalyst for dehydrogenation at the terminal position of the n-alkane. Our continuing work centers on the development of co-catalysts with improved interoperability, particularly olefin-metathesis catalysts that are more robust at high temperature and dehydrogenation catalysts that are more active at low temperature. We are also designing dehydrogenation catalysts based on metals other than iridium. Our ongoing mechanistic studies are focused on the apparently complex combination of factors that determine molecular-weight selectivity. PMID:22584036

Haibach, Michael C; Kundu, Sabuj; Brookhart, Maurice; Goldman, Alan S

2012-06-19

4

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

SciTech Connect

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).

Lyons, J.E.

1992-09-30

5

Hydrogenative deoxygenation of organic compounds: Direct conversion of amides to alkanes  

PubMed Central

Through the use of (Cp2TiH)x or (Cp2Ti)1-2, in which Cp is C5H5 (cyclopentadienyl ligand), it is possible to effect not only the previously known direct reduction of aldehydes and esters to alkanes but also the one-step conversion to alkane of amides derived from selected primary aromatic amines. PMID:16592988

van Tamelen, Eugene E.; Webber, Bruce D.

1981-01-01

6

Products of Chemistry: Alkanes: Abundant, Pervasive, Important, and Essential.  

ERIC Educational Resources Information Center

Discusses the history and commercialization of alkanes. Examines the nomenclature and uses of alkanes. Studies polymerization and several types of polyethylenes: low-density, high-density, low-molecular-weight, cross-linked, linear low-density, and ultrahigh-molecular-weight. Includes a glossary of hydrocarbon terms. (MVL)

Seymour, Raymond B.

1989-01-01

7

Organic Chemistry Self Instructional Package 5: Alkanes Preparations and Reactions.  

ERIC Educational Resources Information Center

This booklet, one of a series of 17 developed at Prince George's Community College, Largo, Maryland, provides an individualized, self-paced undergraduate organic chemistry instruction module designed to augment any course in organic chemistry but particularly those taught using the text "Organic Chemistry" by Morrison and Boyd. The entire series…

Zdravkovich, V.

8

Organic Chemistry Self Instructional Package 4: Alkanes-Nomenclature.  

ERIC Educational Resources Information Center

This booklet, one of a series of 17 developed at Prince George's Community College, Largo, Maryland, provides an individualized, self-paced undergraduate organic chemistry instruction module designed to augment any course in organic chemistry but particularly those taught using the text "Organic Chemistry" by Morrison and Boyd. The entire series…

Zdravkovich, V.

9

C 6-alkane conversion over ?-alumina supported palladium and platinum catalysts  

Microsoft Academic Search

A comparable study of n-hexane and 2,2-dimethylbutane reactions in excess hydrogen carried out on differently loaded Pd\\/Al2O3 and Pt\\/Al2O3 catalysts at ?290°C furnished information which is useful in assessing the role of activated alumina in catalyzing C6-alkane conversion. In particular, it was confirmed that in effect of high temperature reduction (at 600°C) Al2O3 gains a considerable acidity which must play

Maciej Skotak; Zbigniew Karpi?ski

2002-01-01

10

Chemistry of energy conversion and storage.  

PubMed

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

Su, Dang Sheng

2012-03-12

11

Catalytic conversion of light alkanes. Quarterly progress report, April 1--June 30, 1992  

SciTech Connect

The second Quarterly Report of 1992 on the Catalytic Conversion of Light Alkanes reviews the work done between April 1, 1992 and June 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 that can either be used as clean-burning, high octane liquid fuels, as fuel components or as precursors to liquid hydrocarbon uwspomdon 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 regular oxidic lattices including zeolites and related structures as well as other molecular surface structures having metal oxo groups (PHASE I).

Lyons, J.E.

1992-06-30

12

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

SciTech Connect

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).

Lyons, J.E.

1992-09-30

13

Catalytic conversion of light alkanes phase II. Topical report, January 1990--January 1993  

SciTech Connect

The Topical Report on Phase II of the project entitled, Catalytic Conversion of Light Alkanes reviews work done between January 1, 1990 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. This Topical Report documents our efforts 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. Research on the Cooperative Agreement is divided into three Phases relating to three molecular environments for the active catalytic species that we are trying to generate. In this report we present our work on catalysts which have oxidation-active metals in polyoxoanions (PHASE II).

NONE

1998-12-31

14

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

SciTech Connect

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.

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

1993-12-31

15

Light alkane conversion processes - Suprabiotic catalyst systems for selective oxidation of light alkane gases to fuel oxygenates  

SciTech Connect

The objective of the work presented in this paper is to develop new, efficient catalysts for the selective transformation of the light alkanes in natural gas to alcohols for use as liquid transportation fuels, fuel precursors and chemical products. There currently exists no DIRECT one-step catalytic air-oxidation process to convert these substrates to alcohols. Such a one-step route would represent superior useful technology for the utilization of natural gas and similar refinery-derived light hydrocarbon streams. Processes for converting natural gas or its components (methane, ethane, propane, and the butanes) to alcohols for use as motor fuels, fuel additives or fuel precursors will not only add a valuable alternative to crude oil but will produce a clean-burning, high octane alternative to conventional gasoline.

Lyons, J.E.

1992-01-01

16

Light alkane conversion processes - Suprabiotic catalyst systems for selective oxidation of light alkane gases to fuel oxygenates.  

SciTech Connect

The objective of the work presented in this paper is to develop new, efficient catalysts for the selective transformation of the light alkanes in natural gas to alcohols for use as liquid transportation fuels, fuel precursors and chemical products. There currently exists no DIRECT one-step catalytic air-oxidation process to convert these substrates to alcohols. Such a one-step route would represent superior useful technology for the utilization of natural gas and similar refinery-derived light hydrocarbon streams. Processes for converting natural gas or its components (methane, ethane, propane, and the butanes) to alcohols for use as motor fuels, fuel additives or fuel precursors will not only add a valuable alternative to crude oil but will produce a clean-burning, high octane alternative to conventional gasoline.

Lyons, J.E.

1992-07-01

17

Catalytic conversion of light alkanes, Phase 3. Topical report, January 1990--December 1992  

SciTech Connect

The mission of this work is to devise a new catalyst which can be used in the first simple, economic process to convert the light alkanes in natural gas to an alcohol-rich oxygenated product which can either be used as an environmentally friendly, high-performance liquid fuel, or a precursor to a liquid hydrocarbon transportation fuel. The authors have entered the proof-of-concept stage for converting isobutane to tert butyl alcohol in a practical process and are preparing to enter proof-of-concept of a propane to isopropyl alcohol process in the near future. Methane and ethane are more refractory and thus more difficult to oxidize than the C{sub 3} and C{sub 4} hydrocarbons. Nonetheless, advances made in this area indicate that further research progress could achieve the goal of their direct conversion to alcohols. Progress in Phase 3 catalytic vapor phase methane and ethane oxidation over metals in regular oxidic lattices are the subject of this topical report.

NONE

1992-12-31

18

A Process for Microbial Hydrocarbon Synthesis: Overproduction of Fatty Acids in Escherichia coli and Catalytic Conversion to Alkanes  

PubMed Central

The development of renewable alternatives to diesel and jet fuels is highly desirable for the heavy transportation sector, and would offer benefits over the production and use of short-chain alcohols for personal transportation. Here, we report the development of a metabolically engineered strain of Escherichia coli that overproduces medium-chain length fatty acids via three basic modifications: elimination of ?-oxidation, overexpression of the four subunits of acetyl-CoA carboxylase, and expression of a plant acyl–acyl carrier protein (ACP) thioesterase from Umbellularia californica (BTE). The expression level of BTE was optimized by comparing fatty acid production from strains harboring BTE on plasmids with four different copy numbers. Expression of BTE from low copy number plasmids resulted in the highest fatty acid production. Up to a seven-fold increase in total fatty acid production was observed in engineered strains over a negative control strain (lacking ?-oxidation), with a composition dominated by C12 and C14 saturated and unsaturated fatty acids. Next, a strategy for producing undecane via a combination of biotechnology and heterogeneous catalysis is demonstrated. Fatty acids were extracted from a culture of an overproducing strain into an alkane phase and fed to a Pd/C plug flow reactor, where the extracted fatty acids were decarboxylated into saturated alkanes. The result is an enriched alkane stream that can be recycled for continuous extractions. Complete conversion of C12 fatty acids extracted from culture to alkanes has been demonstrated yielding a concentration of 0.44 g L?1 (culture volume) undecane. PMID:20073090

Lennen, Rebecca M.; Braden, Drew J.; West, Ryan M.; Dumesic, James A.; Pfleger, Brian F.

2013-01-01

19

An Acid-Base Chemistry Example: Conversion of Nicotine  

NASA Astrophysics Data System (ADS)

The current government interest in nicotine conversion by cigarette companies provides an example of acid-base chemistry that can be explained to students in the second semester of general chemistry. In particular, the conversion by ammonia of the +1 form of nicotine to the easier-to-assimilate free-base form illustrates the effect of pH on acid-base equilibrium. The part played by ammonia in tobacco smoke is analogous to what takes place when cocaine is "free-based".

Summerfield, John H.

1999-10-01

20

Gas-Phase Tropospheric Chemistry of Volatile Organic Compounds: 1. Alkanes and Alkenes  

Microsoft Academic Search

Literature data (through mid-1996) concerning the gas-phase reactions of alkanes and alkenes (including isoprene and monoterpenes) leading to their first generation products are reviewed and evaluated for tropospheric conditions. The recommendations of the most recent IUPAC evaluation [J. Phys. Chem. Ref. Data, 26, No. 3 (1997)] are used for the ?C3 organic compounds, unless more recent data necessitates reevaluation. The

Roger Atkinson

1997-01-01

21

Organic Chemistry Self Instructional Package 3: Alkanes-Homologous Series and Isomerism.  

ERIC Educational Resources Information Center

This booklet, one of a series of 17 developed at Prince George's Community College, Largo, Maryland, provides an individualized, self-paced undergraduate organic chemistry instruction module designed to augment any course in organic chemistry but particularly those taught using the text "Organic Chemistry" by Morrison and Boyd. The entire series…

Zdravkovich, V.

22

Catalytic conversion of light alkanes. Final report, January 1, 1990--October 31, 1994  

SciTech Connect

During the course of the first three years of the Cooperative Agreement (Phase I-III), we uncovered a family of metal perhaloporphyrin complexes which had unprecedented activity for the selective air-oxidation of fight alkanes to alcohols. The reactivity of fight hydrocarbon substrates with air or oxygen was in the order: isobutane>propane>ethane>methane, in accord with their homolytic bond dissociation energies. Isobutane was so reactive that the proof-of concept stage of a process for producing tert-butyl alcohol from isobutane was begun (Phase V). It was proposed that as more active catalytic systems were developed (Phases IV, VI), propane, then ethane and finally methane oxidations will move into this stage (Phases VII through IX). As of this writing, however, the program has been terminated during the later stages of Phases V and VI so that further work is not anticipated. We made excellent progress during 1994 in generating a class of less costly new materials which have the potential for high catalytic activity. New routes were developed for replacing costly perfluorophenyl groups in the meso-position of metalloporphyrin catalysts with far less expensive and lower molecular weight perfluoromethyl groups.

NONE

1998-12-31

23

Catalytic conversion of light alkanes-proof-of-concept stage -- Phase 6. Final report, February 1--October 31, 1994  

SciTech Connect

During the course of the first three years of the Cooperative Agreement, the authors uncovered a family of metal perhaloporphyrin complexes which had unprecedented activity for the selective air-oxidation of light alkanes to alcohols. The reactivity of light hydrocarbon substrates with air or oxygen was in the order: isobutane > propane > ethane > methane, in accord with their homolytic bond dissociation energies. Isobutane was so reactive that the proof-of-concept stage of a process for producing tert-butyl alcohol from isobutane was begun (Phase 5). It was proposed that as more active catalytic systems were developed (Phases 4, 6), propane, then ethane and finally methane oxidations will move into this stage (Phases 7 through 9). As of this writing, however, the program has been terminated during the later stages of Phase 5 and 6 so that further work is not anticipated. 72 refs.

NONE

1994-12-31

24

Catalytic conversion of light alkanes-proof-of-concept stage - Phase IV. Topical report, February 1, 1994--January 31, 1995  

SciTech Connect

This report details the research performed on Phase IV of the extended Cooperative Agreement. This Phase, entitled C{sub 1}-C{sub 4} Research, provides the research support which accompanies the C{sub 4} Proof-of-Concept Phase (Phase V) as the two major activities of the Cooperative Agreement during calendar 1993. It is the objective of this phase to understand the nature of the catalysts and catalytic activity of perhaloporphyrin complexes uncovered during Phases I-III in order that superior catalytic materials can be made and tested which meet commercial criteria for the oxidation of the C{sub 1}-C{sub 4} light alkane gases found in natural gas and other available hydrocarbon streams. During Phase IV, we have examined the physical and electronic structures of the very active perhaloporphyrin catalysts which we have developed, and have gained an understanding of the properties which make them active. This has led us to design and synthesize materials which are cheaper, more active, more robust and, in general superior for carrying out practical catalysis. Our early generation perhaloporphyrin catalysts, while exhibiting unprecedented catalytic activity, were far too expensive for use in converting natural gas or its C{sub 1}-C{sub 4} components.

NONE

1998-12-31

25

Polyoxometalate systems for the catalytic selective production of nonthermodynamic alkenes from alkanes. Nature of excited-state deactivation processes and control of subsequent thermal processes in polyoxometalate photoredox chemistry  

SciTech Connect

The photooxidations of exemplary branched acyclic alkanes and cycloalkanes by a range of polyoxotungstates varying in charge density, ground-state redox potential, acidity, and other properties were examined in detail. The organic products generated in these reactions depend on the polyoxometalate used, and in particular on the ground-state redox potential of the complex. Under anaerobic conditions acyclic branched alkanes yield principally alkenes, while cycloalkanes yield principally alkenes and dimers. Alkyl methyl ketones, derived in part from reaction with acetonitrile solvent, and isomerized alkanes are produced with some alkane substrates. Under aerobic conditions, autoxidation, initiated by radicals generated in the photoinduced redox chemistry, is observed. Under aerobic conditions the polyoxotungstates with formal redox potentials more negative than {minus}1.0 V vs Ag/AgNO{sub 3}(CH{sub 3}CN), such as W{sub 10}O{sub 32}{sup 4{minus}} and W{sub 6}O{sub 19}{sup 2{minus}}, photochemically dehydrogenate branched acyclic alkanes in high selectivity to {alpha}-olefins and the least substituted alkenes, products heretofore undocumented in photooxidation reactions catalyzed by polyoxometalates.

Renneke, R.F.; Pasquali, M.; Hill, C.L. (Emory Univ., Atlanta, GA (USA))

1990-08-29

26

Symposium on the Physical Chemistry of Solar Energy Conversion, Indianapolis American Chemical Society Meetings, Fall 2013  

SciTech Connect

The Symposium on the Physical Chemistry of Solar Energy Conversion at the Fall ACS Meeting in Indianapolis, IN (Sept. 8-12) featured the following sessions (approx. 6 speakers per session): (1) Quantum Dots and Nanorods for Solar Energy Conversion (2 half-day sessions); (2) Artificial Photosynthesis: Water Oxidation; (3) Artificial Photosynthesis: Solar Fuels (2 half-day sessions); (4) Organic Solar Cells; (5) Novel Concepts for Solar Energy Conversion (2 half-day sessions); (6) Emerging Techniques for Solar Energy Conversion; (7) Interfacial Electron Transfer

Lian, Tianquan [PI, Emory Univ.

2013-09-01

27

ATMOSPHERIC CHEMISTRY OF POTENTIAL EMISSIONS FROM FUEL CONVERSION FACILITIES. A SMOG CHAMBER STUDY  

EPA Science Inventory

The atmospheric chemistry of chemical species that may be emitted from fuel conversion facilities were studied in smog chambers. Of 17 compounds assessed for ozone-forming potential, 6 compounds were selected along with a control species, propylene, for testing in the presence of...

28

EDITORIAL: Non-thermal plasma-assisted fuel conversion for green chemistry Non-thermal plasma-assisted fuel conversion for green chemistry  

NASA Astrophysics Data System (ADS)

This special issue is based on the symposium on Non-thermal Plasma Assisted Fuel Conversion for Green Chemistry, a part of the 240th ACS National Meeting & Exposition held in Boston, MA, USA, 22-26 August 2010. Historically, the Division of Fuel Chemistry of the American Chemical Society (ACS) has featured three plasma-related symposia since 2000, and has launched special issues in Catalysis Today on three occasions: 'Catalyst Preparation using Plasma Technologies', Fall Meeting, Washington DC, USA, 2000. Special issue in Catalysis Today 72 (3-4) with 12 peer-reviewed articles. 'Plasma Technology and Catalysis', Spring Meeting, New Orleans, LA, USA, 2003. Special issue in Catalysis Today 89 (1-2) with more than 30 peer-reviewed articles. 'Utilization of Greenhouse Gases II' (partly focused on plasma-related technologies), Spring Meeting, Anaheim, CA, USA, 2004. Special issue in Catalysis Today 98 (4) with 25 peer-reviewed articles. This time, selected presentations are published in this Journal of Physics D: Applied Physics special issue. An industrial material and energy conversion technology platform is established on thermochemical processes including various catalytic reactions. Existing industry-scale technology is already well established; nevertheless, further improvement in energy efficiency and material saving has been continuously demanded. Drastic reduction of CO2 emission is also drawing keen attention with increasing recognition of energy and environmental issues. Green chemistry is a rapidly growing research field, and frequently highlights renewable bioenergy, bioprocesses, solar photocatalysis of water splitting, and regeneration of CO2 into useful chemicals. We would also like to emphasize 'plasma catalysis' of hydrocarbon resources as an important part of the innovative next-generation green technologies. The peculiarity of non-thermal plasma is that it can generate reactive species almost independently of reaction temperature. Plasma-generated reactive species are used to initiate chemical reactions at unexpectedly lower temperatures than conventional thermochemical reactions, leading to non-equilibrium product distribution or creating unconventional reaction pathways. When non-thermal plasma is combined with catalysts, a synergistic effect is frequently observed. Such unique properties of non-thermal plasma are expected to contribute excellent control over process parameters that meet the need for energy saving, environment protection, and material preservation. This special issue consists of eleven peer-reviewed papers including two invited publications. Professors Alexander Fridman and Alexander Rabinovich from Drexel University, and Dr Gutsol from the Chevron Energy Technology Company present a critical review of various industry-oriented practical plasma fuel conversion processes. Professor Richard Mallinson from University of Oklahoma describes his recent project on E85 (85%-ethanol/15%-gasoline) upgrading using non-thermal plasma and catalyst hybrid reactor, and highlights the synergistic effect on fuel conversion processes. Other papers focus on plasma/catalyst hybrid reactions for methane dry (CO2) reforming, plasma synthesis of carbon suboxide polymer from CO, the gas-to-liquid (GTL) process using a non-thermal plasma-combined micro-chemical reactor, and molecular beam characterization of plasma-generated reactive species. Much research regarding plasma catalysis is ongoing worldwide, but there is plenty of room for further development of plasma fuel processing, which could eventually provide a viable and flexible solution in future energy and material use. Finally, we would like to thank all symposium participants for their active discussion. We appreciate the sponsorship of the Division of Fuel Chemistry of the American Chemical Society. We express special thanks to the program chair of the Fuel Chemistry Division, Professor Chang-jun Liu at Tianjin University, for his dedication to the success of the symposium. We particularly express our appreciation to the Editorial Board of Journal

Nozaki, Tomohiro; Gutsol, Alexander

2011-07-01

29

Organic Chemistry  

NSDL National Science Digital Library

R. H. Logan, an chemistry instructor at North Lake College, created this introduction to organic chemistry. The introduction covers a eight types of organic compounds, including Alkanes, Alkyl Halides, and Acyl Compounds (forthcoming); Conformational Analysis and Stereoisomerism; and Instrumental Analysis of Organic Compounds, as well an extensive lesson in general chemistry.

30

Characterisation of alkane ?-complexes.  

PubMed

Alkane ?-complexes have evolved from a curious phenomenon to an intermediate of intense interest, fuelling research into the area. Over the last fifteen years, metal alkane complex characterisation has evolved to incorporate reports employing UV/Vis, IR and NMR spectroscopy, and X-ray and neutron diffractometry. Previously, due to the sparse geometric characterisation of alkane ?-complexes, assumptions regarding bonding geometries and selectivities were made by comparison to related ?-complexes, or by analysis of C-H activation products. This minireview assembles relevant literature that illuminates the metrics of alkane-metal bonding, and critically analyses the binding mode, selectivity and stability of alkane complexes. PMID:25196671

Young, Rowan D

2014-09-26

31

SYNFORMPeople, Trends and Views in Synthetic Organic Chemistry Direct Conversion of Arylamines  

E-print Network

SYNFORMPeople, Trends and Views in Synthetic Organic Chemistry 2010/05 Thieme SYNSTORIES Direct the organic molecules which are essential components of drugs, materials, agrochemicals, and all the organic-chemistry about SYNFORM is welcome, please correspond if you like: marketing@thieme-chemistry.com Downloadedby

Wang, Jianbo

32

Homogeneous catalytic photochemical functionalization of alkanes by polyoxometalates  

SciTech Connect

Progress in the last 5 years toward the activation and functionalization of alkanes, the most abundant but least reactive class of organic compounds, has been substantial. Thorough investigations of several homogeneous liquid-phase systems for alkane activation or functionalization at 25/sup 0/C have now been reported. These include organometallic systems that effect stoichiometric alkane C-H bond activation with unusual C-H cleavage selectivities (least hindered positions most reactive) and metalloporphyrin systems that effect catalytic alkane functionalization with conventional C-H cleavage selectivities (tertiary C-H most reactive). Reported here, as part of the continuing efforts to develop soluble metal oxides species as superior catalysts for energetic and synthetic transformations of interest, is a new methodology for the homogeneous liquid-phase activation and functionalization of alkanes. This chemistry involves the irradiation of heteropolytungstic acids and alkanes in acetonitrile solution. The heteropolytungstic acids, unlike all alkane-activating organometallic and metalloporphyrin species in the literature, contain no oxidizable organic structure. The very high oxidative stability of the soluble and completely inorganic polyoxometalates, recently documented for catalytic thermal epoxidation processes, is now demonstrated for catalytic photochemical organic oxidation processes.

Renneke, R.F.; Hill, C.L.

1986-06-11

33

CONFORMATIONS OF ALKANES AND CYCLOALKANES  

E-print Network

89 CHAPTER 3 CONFORMATIONS OF ALKANES AND CYCLOALKANES H ydrogen peroxide is formed in the cells this chapter we'll examine the conformations of various alkanes and cycloal- kanes, focusing most of our that are placed symmetrically around it. 90 CHAPTER THREE Conformations of Alkanes and Cycloalkanes Eclipsed

Ferreira, Márcia M. C.

34

Chemistry  

NSDL National Science Digital Library

Finds ChemEd DL resources related to the sections of the General Chemistry textbook, Chemistry, by Kenneth W. Whitten, Raymond E. Davis, M. Larry Peck, George G. Stanley published by Brooks/Cole, 2010.

35

Towards a practical development of light-driven acceptorless alkane dehydrogenation.  

PubMed

The efficient catalytic dehydrogenation of alkanes to olefins is one of the most investigated reactions in organic synthesis. In the coming years, an increased supply of shorter-chain alkanes from natural and shale gas will offer new opportunities for inexpensive carbon feedstock through such dehydrogenation processes. Existing methods for alkane dehydrogenation using heterogeneous catalysts require harsh reaction conditions and have a lack of selectivity, whereas homogeneous catalysis methods result in significant waste generation. A strong need exists for atom-efficient alkane dehydrogenations on a useful scale. Herein, we have developed improved acceptorless catalytic systems under optimal light transmittance conditions using trans-[Rh(PMe3)2(CO)Cl] as the catalyst with different additives. Unprecedented catalyst turnover numbers are obtained for the dehydrogenation of cyclic and linear (from C4) alkanes and liquid organic hydrogen carriers. These reactions proceed with unique conversion, thereby providing a basis for practical alkane dehydrogenations. PMID:24829085

Chowdhury, Abhishek Dutta; Weding, Nico; Julis, Jennifer; Franke, Robert; Jackstell, Ralf; Beller, Matthias

2014-06-16

36

Catalytic oxidation of light alkanes in presence of a base  

DOEpatents

The presence of a base in the reaction mixture in a metal-ligand catalyzed partial oxidation of alkanes results in sustained catalyst activity, and in greater percent conversion as compared with oxidation in the absence of base, while maintaining satisfactory selectivity for the desired oxidation, for example the oxidation of isobutane to isobutanol. 1 fig.

Bhinde, M.V.; Bierl, T.W.

1998-03-03

37

Catalytic oxidation of light alkanes in presence of a base  

DOEpatents

The presence of a base in the reaction mixture in a metal-ligand catalyzed partial oxidation of alkanes results in sustained catalyst activity, and in greater percent conversion as compared with oxidation in the absence of base, while maintaining satisfactory selectivity for the desired oxidation, for example the oxidation of isobutane to isobutanol.

Bhinde, Manoj V. (Boothwyn, PA); Bierl, Thomas W. (West Chester, PA)

1998-01-01

38

Ceramic nanoparticle assemblies with tailored shapes and tailored chemistries via biosculpting and shape-preserving inorganic conversion.  

PubMed

A novel biosynthetic paradigm is introduced for fabricating three-dimensional (3-D) ceramic nanoparticle assemblies with tailored shapes and tailored chemistries: biosculpting and shape-preserving inorganic conversion (BaSIC). Biosculpting refers to the use of biomolecules that direct the precipitation of ceramic nanoparticles to form a continuous 3-D structure with a tailored shape. We used a peptide derived from a diatom (a type of unicellular algae) to biosculpt silica nanoparticle based assemblies that, in turn, were converted into a new (nonsilica) composition via a shape-preserving gas/silica displacement reaction. Interwoven, microfilamentary silica structures were prepared by exposing a peptide, derived from the silaffin-1A protein of the diatom Cylindrotheca fusiformis, to a tetramethylorthosilicate solution under a linear shear flow condition. Subsequent exposure of the silica microfilaments to magnesium gas at 900 degrees C resulted in conversion into nanocrystalline magnesium oxide microfilaments with a retention of fine (submicrometer) features. Fluid(gas or liquid)/silica displacement reactions leading to a variety of other oxides have also been identified. This hybrid (biogenic/synthetic) approach opens the door to biosculpted ceramic microcomponents with multifarious tailored shapes and compositions for a wide range of environmental, aerospace, biomedical, chemical, telecommunications, automotive, manufacturing, and defense applications. PMID:15762162

Dickerson, M B; Naik, R R; Sarosi, P M; Agarwal, G; Stone, M O; Sandhage, K H

2005-01-01

39

High Temperature Chemical Kinetic Combustion Modeling of Lightly Methylated Alkanes  

SciTech Connect

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.

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

2011-03-01

40

Alkane desaturation by concerted double hydrogen atom transfer to benzyne.  

PubMed

The removal of two vicinal hydrogen atoms from an alkane to produce an alkene is a challenge for synthetic chemists. In nature, desaturases and acetylenases are adept at achieving this essential oxidative functionalization reaction, for example during the biosynthesis of unsaturated fatty acids, eicosanoids, gibberellins and carotenoids. Alkane-to-alkene conversion almost always involves one or more chemical intermediates in a multistep reaction pathway; these may be either isolable species (such as alcohols or alkyl halides) or reactive intermediates (such as carbocations, alkyl radicals, or ?-alkyl-metal species). Here we report a desaturation reaction of simple, unactivated alkanes that is mechanistically unique. We show that benzynes are capable of the concerted removal of two vicinal hydrogen atoms from a hydrocarbon. The discovery of this exothermic, net redox process was enabled by the simple thermal generation of reactive benzyne intermediates through the hexadehydro-Diels-Alder cycloisomerization reaction of triyne substrates. We are not aware of any single-step, bimolecular reaction in which two hydrogen atoms are simultaneously transferred from a saturated alkane. Computational studies indicate a preferred geometry with eclipsed vicinal C-H bonds in the alkane donor. PMID:24067712

Niu, Dawen; Willoughby, Patrick H; Woods, Brian P; Baire, Beeraiah; Hoye, Thomas R

2013-09-26

41

Room-temperature alkane reactivity in zeolites: an H/D exchange study.  

PubMed

As evidenced by H/D exchange with acidic zeolites, isoalkanes react readily at room temperature whereas linear alkanes do not. The observed regioselectivity of the exchange process demonstrates that the main factor controlling the reaction is not the accessibility to the acid sites, but the intrinsic reactivity of the alkane. The mechanism is best rationalized by classic organic chemistry involving carbocationic intermediates including the Markovnikov rule. PMID:20108278

Sido, Abdelkarim Sani Souna; Walspurger, Stéphane; Barbiche, Jérémy; Sommer, Jean

2010-03-01

42

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

E-print Network

Molecular and Thermal Diffusion Coefficients of Alkane-Alkane and Alkane-Aromatic Binary Mixtures decane-normal alkanes and methylnaphthalene-normal alkanes are measured at atmospheric pressure and T ) 25 °C. The normal alkanes used in this work include nC5-nC20. Thermal diffusion coefficients were

Firoozabadi, Abbas

43

Laboratory evolution of a soluble, self-sufficient, highly active alkane hydroxylase  

Microsoft Academic Search

We have converted cytochrome P450 BM-3 from Bacillus megaterium (P450 BM-3), a medium-chain (C12–C18) fatty acid monooxygenase, into a highly efficient catalyst for the conversion of alkanes to alcohols. The evolved P450 BM-3 exhibits higher turnover rates than any reported biocatalyst for the selective oxidation of hydrocarbons of small to medium chain length (C3–C8). Unlike naturally occurring alkane hydroxylases, the

Anton Glieder; Edgardo T. Farinas; Frances H. Arnold

2002-01-01

44

Chemistry  

NSDL National Science Digital Library

These sites willhelp you gain greater understanding of Chemistry! Weather is also available Three areas to be on the test. STUDY HARD!!!! Equations Types of Equations Types of Equations text/htmlMichigan Teacher Network Matter Density of solids Density of solids text/htmlICSD ScienceZone Metals Kidneys and Metals Problem Set Kidneys and Metals Problem Set image/tiffCenter for Digital Curriculum Research POTENTIAL SURROGATE METALS FOR INCINERATOR TRIAL BURNS POTENTIAL SURROGATE METALS FOR INCINERATOR TRIAL BURNS text/html Let it snow Interactive Weather Maker Interactive Weather Maker urlexample ...

Riley

2006-04-22

45

Superacid catalysis of light hydrocarbon conversion. Sixth quarterly report, January 1, 1995--March 31, 1995  

SciTech Connect

Iron- and Manganese-promoted sulfated zirconia is a catalyst for the conversion of propane, but the rate of conversion of propane is much less than the rate of conversion of butane. Whereas this catalyst appears to be a good candidate for practical, industrial conversion of butane, it appears to lack sufficient activity for practical conversion of propane. Perhaps more active catalysts will be useful for propane conversion. The propane conversion data reported here provide excellent insights into the chemistry of the catalytic conversions; they are consistent with the inference that the catalyst is a superacid and that the chemistry is analogous to. that determined in superacid solutions by G.A. Olah, who was awarded the most recent Nobel Prize in chemistry for his work. The catalyst was tested for conversion of propane at 1 bar, 200--300{degrees}C and propane partial pressures in the range of 0.01--0.05 bar. At 250{degrees}C, catalysis was demonstrated, as the number of propane molecules converted was at least 1 per sulfate group after 16 days of operation in a continues flow reactor. Propane was converted in high yield to butanes, but the conversions were low, for example being only a fraction of a percent at a space velocity of 9.1 {times} 10{sup {minus}7} mol(g of catalysis {center_dot} s) and 250{degrees}C. Coke formation was rapid. The observation of butanes, pentanes, and methane as products is consistent with Olah superacid chemistry, whereby propane is first protonated by a very strong acid to form a carbonium ion. The carbonium ion then decomposes into methane and an ethyl cation which undergoes oligocondensation reactions with propane to form higher molecular weight alkanes. The results are consistent with the identification of iron- and manganese-promoted sulfated zirconia as a superacid.

Gates, B.C. [California Univ., Davis, CA (United States). Dept. of Chemical Engineering and Materials Science

1995-08-01

46

Theoretical Description of the STM Images of Alkanes and Substituted Alkanes Adsorbed on Graphite  

E-print Network

Theoretical Description of the STM Images of Alkanes and Substituted Alkanes Adsorbed on Graphite the STM images of alkanes on graphite surfaces. The computations correlate well with the STM data of functionalized alkanes and allow assessment of the structure and orientation of most of the functionalized

Goddard III, William A.

47

Alkane Coordination Selectivity in Hydrocarbon Activation by [TpRh(CNneopentyl)]: The Role of Alkane Complexes  

E-print Network

Alkane Coordination Selectivity in Hydrocarbon Activation by [TpRh(CNneopentyl)]: The Role of Alkane Complexes Andrew J. Vetter, Christine Flaschenriem, and William D. Jones* Contribution from in many cases that activation of alkanes occurs through a two-step process: formation of a -alkane complex

Jones, William D.

48

Integrated process for preparing a carboxylic acid from an alkane  

DOEpatents

The present invention relates to an integrated process for producing unsaturated carboxylic acids from the corresponding C.sub.2-C.sub.4 alkane. The process begins with performance of thermally integrated dehydrogenation reactions which convert a C.sub.2-C.sub.4 alkane to its corresponding C.sub.2-C.sub.4 alkene, and which involve exothermically converting a portion of an alkane to its corresponding alkene by oxidative dehydrogenation in an exothermic reaction zone, in the presence of oxygen and a suitable catalyst, and then feeding the products of the exothermic reaction zone to an endothermic reaction zone wherein at least a portion of the remaining unconverted alkane is endothermically dehydrogenated to form an additional quantity of the same corresponding alkene, in the presence of carbon dioxide and an other suitable catalyst. The alkene products of the thermally integrated dehydrogenation reactions are then provided to a catalytic vapor phase partial oxidation process for conversion of the alkene to the corresponding unsaturated carboxylic acid or nitrile. Unreacted alkene and carbon dioxide are recovered from the oxidation product stream and recycled back to the thermally integrated dehydrogenation reactions.

Benderly, Abraham (Elkins Park, PA); Chadda, Nitin (Radnor, PA); Sevon, Douglass (Fairless Hills, PA)

2011-12-20

49

Liquid-liquid interfaces of semifluorinated alkane diblock copolymers with water, alkanes, and perfluorinated alkanes.  

SciTech Connect

The liquid-liquid interface between semifluorinated alkane diblock copolymers of the form F3C(CF2)n-1-(CH2)m-1CH3 and water, protonated alkanes, and perfluorinated alkanes are studied by fully atomistic molecular dynamics simulations. A modified version of the OPLS-AA (Optimized Parameter for Liquid Simulation All-Atom) force field of Jorgensen et al. has been used to study the interfacial behavior of semifluorinated diblocks. Aqueous interfaces are found to be sharp, with correspondingly large values of the interfacial tension. Due to the reduced hydrophobicity of the protonated block compared to the fluorinated block, hydrogen enhancement is observed at the interface. Water dipoles in the interfacial region are found to be oriented nearly parallel to the liquid-liquid interface. A number of protonated alkanes and perfluorinated alkanes are found to be mutually miscible with the semifluorinated diblocks. For these liquids, interdiffusion follows the expected Fickian behavior, and concentration-dependent diffusivities are determined.

Perahia, Dvora, Dr. (Clemson University, Clemson, SC); Pierce, Flint (Clemson University, Clemson, SC); Tsige, Mesfin (Southern Illinois University, Carbondale, IL); Grest, Gary Stephen, Dr.

2008-08-01

50

Photocatalytic Acceptorless Alkane Dehydrogenation: Scope, Mechanism, and Conquering Deactivation with Carbon Dioxide.  

PubMed

Alkane dehydrogenation is of special interest for basic science but also offers interesting opportunities for industry. The existing dehydrogenation methodologies make use of heterogeneous catalysts, which suffer from harsh reaction conditions and a lack of selectivity, whereas homogeneous methodologies rely mostly on unsolicited waste generation from hydrogen acceptors. Conversely, acceptorless photochemical alkane dehydrogenation in the presence of trans-Rh(PMe3 )2 (CO)Cl can be regarded as a more benign and atom efficient alternative. However, this methodology suffers from catalyst deactivation over time. Herein, we provide a detailed investigation of the trans-Rh(PMe3 )2 (CO)Cl-photocatalyzed alkane dehydrogenation using spectroscopic and theoretical investigations. These studies inspired us to utilize CO2 to prevent catalyst deactivation, which leads eventually to improved catalyst turnover numbers in the dehydrogenation of alkanes that include liquid organic hydrogen carriers. PMID:25346450

Chowdhury, Abhishek Dutta; Julis, Jennifer; Grabow, Kathleen; Hannebauer, Bernd; Bentrup, Ursula; Adam, Martin; Franke, Robert; Jackstell, Ralf; Beller, Matthias

2014-10-24

51

Secondary Organic Aerosol Composition from C12 Alkanes.  

PubMed

The effects of structure, NOx conditions, relative humidity, and aerosol acidity on the chemical composition of secondary organic aerosol (SOA) are reported for the photooxidation of three C12 alkanes: n-dodecane, cyclododecane, and hexylcyclohexane. Acidity was modified through seed particle composition: NaCl, (NH4)2SO4, and (NH4)2SO4 + H2SO4. Off-line analysis of SOA was carried out by solvent extraction and gas chromatography-mass spectrometry (GC/MS) and direct analysis in real-time mass spectrometry. We report here 750 individual masses of SOA products identified from these three alkane systems and 324 isomers resolved by GC/MS analysis. The chemical compositions for each alkane system provide compelling evidence of particle-phase chemistry, including reactions leading to oligomer formation. Major oligomeric species for alkane SOA are peroxyhemiacetals, hemiacetals, esters, and aldol condensation products. Furans, dihydrofurans, hydroxycarbonyls, and their corresponding imine analogues are important participants in these oligomer-producing reactions. Imines are formed in the particle phase from the reaction of the ammonium sulfate seed aerosol with carbonyl-bearing compounds present in all the SOA systems. Under high-NO conditions, organonitrate products can lead to an increase of aerosol volume concentration by up to a factor of 5 over that in low-NO conditions. Structure was found to play a key role in determining the degree of functionalization and fragmentation of the parent alkane, influencing the mean molecular weight of the SOA produced and the mean atomic O:C ratio. PMID:24814371

Schilling Fahnestock, Katherine A; Yee, Lindsay D; Loza, Christine L; Coggon, Matthew M; Schwantes, Rebecca; Zhang, Xuan; Dalleska, Nathan F; Seinfeld, John H

2014-05-22

52

Temperature-Dependent Terahertz Spectroscopy of Liquid n-alkanes  

E-print Network

Temperature-Dependent Terahertz Spectroscopy of Liquid n-alkanes Jonathan P. Laib & Daniel M alkanes. We study all of the liquid alkanes from pentane (C5) to hexadecane (C16) over the temperature-molecular interactions in non-polar hydrocarbons. Keywords Alkane . Terahertz The normal alkanes have been the subject

Mittleman, Daniel

53

Oxidation Products of Semi-volatile Alkanes by Hydroxyl Radicals  

NASA Astrophysics Data System (ADS)

Alkanes are ubiquitous in the atmosphere and are important components that influence atmospheric chemistry. Semi-volatile alkanes are partitioned between the gas- and the particle-phases and can be readily oxidized in both phases. Previous studies have demonstrated that reaction rates and the products of OH oxidation are very different for organic compounds in the gas- and particle phases. In the present study, n-octadecane (C18H38), n-eicosane (C20H42), n-docosane (C22H46), n-tricosane (C24H50), and n-pentadecylcyclohexane (C21H42) were chosen as model compounds for semi-volatile alkanes to examine their OH-initiated oxidation reactions in a flow tube reactor. OH exposure was varied in the experiments, equivalent to oxidation of up to one week in the atmosphere. Oxidation products were collected on filters and analyzed using two-dimensional gas chromatography coupled to a high-resolution time-of-flight electron impact ionization and vacuum ultraviolet photoionization mass spectrometer. Most of the oxygenated higher molecular weight isomers were separated and quantified. Our results suggest that aerosol samples formed in the n-octadecane experiment were more oxidized than the other model compounds (i.e., functionalization products with three oxygen atoms per molecule compared to two oxygen atoms per molecule) at similar OH exposures and aerosol mass loadings. This is likely due to the concentration of n-octadecane in the gas phase where oxidation is more rapid. We find that the first-generation gas-phase oxidation products quickly partition to the particle phase after which higher-generation oxidation likely occurs in the particle phase. Interestingly, functionalized carbonyl isomers for the normal alkanes were only observed on the 4 carbon positions closest to the molecule end in all cases, which is in contrast to structure-reactivity relationship (SRR) predictions for gas-phase reactions. For n-octadecane, the concentrations of first-generation functionalization products decreased on carbon positions closer to the molecule end. This trend is reversed for the other three normal alkanes, which show similar results to a recent study on heterogeneous oxidation of non-volatile alkane aerosols. Oxidation of n-pentadecylcyclohexane produces carbonyl and alcohol products on both the hexane ring and the side chain. Ring-opening products were not observed, likely due to the low ring strain energy of the hexane ring. This work provides insights into the oxidation mechanisms of semi-volatile organics leading to secondary aerosol formation and aging.

Zhang, H.; Worton, D. R.; Nah, T.; Goldstein, A. H.; Wilson, K. R.

2013-12-01

54

Genetics of alkane oxidation by Pseudomonas oleovorans  

Microsoft Academic Search

Many Pseudomonads are able to use linear alkanes as sole carbon and energy source. The genetics and enzymology of alkane metabolism have been investigated in depth forPseudomonas oleovorans, which is able to oxidize C5-C12 n-alkanes by virtue of two gene regions, localized on the OCT-plasmid. The so-calledalk-genes have been cloned in pLAFR1, and were subsequent analyzed using minicell expression experiments,

Jan B. Beilen; Marcel G. Wubbolts; Bernard Witholt

1994-01-01

55

40 CFR 721.10163 - Chloro fluoro alkane (generic).  

Code of Federal Regulations, 2014 CFR

...2014-07-01 false Chloro fluoro alkane (generic). 721.10163 Section...Substances § 721.10163 Chloro fluoro alkane (generic). (a) Chemical substance...identified generically as chloro fluoro alkane (PMN P-08-33) is subject to...

2014-07-01

56

40 CFR 721.10163 - Chloro fluoro alkane (generic).  

Code of Federal Regulations, 2010 CFR

...2010-07-01 false Chloro fluoro alkane (generic). 721.10163 Section...Substances § 721.10163 Chloro fluoro alkane (generic). (a) Chemical substance...identified generically as chloro fluoro alkane (PMN P-08-33) is subject to...

2010-07-01

57

40 CFR 721.10163 - Chloro fluoro alkane (generic).  

Code of Federal Regulations, 2012 CFR

...2012-07-01 false Chloro fluoro alkane (generic). 721.10163 Section...Substances § 721.10163 Chloro fluoro alkane (generic). (a) Chemical substance...identified generically as chloro fluoro alkane (PMN P-08-33) is subject to...

2012-07-01

58

40 CFR 721.535 - Halogenated alkane (generic).  

Code of Federal Regulations, 2014 CFR

... 2014-07-01 false Halogenated alkane (generic). 721.535 Section 721...Substances § 721.535 Halogenated alkane (generic). (a) Chemical substance...substance identified generically as halogenated alkane (PMN P-01-433) is subject to...

2014-07-01

59

40 CFR 721.10163 - Chloro fluoro alkane (generic).  

Code of Federal Regulations, 2011 CFR

...2011-07-01 false Chloro fluoro alkane (generic). 721.10163 Section...Substances § 721.10163 Chloro fluoro alkane (generic). (a) Chemical substance...identified generically as chloro fluoro alkane (PMN P-08-33) is subject to...

2011-07-01

60

40 CFR 721.10163 - Chloro fluoro alkane (generic).  

Code of Federal Regulations, 2013 CFR

...2013-07-01 false Chloro fluoro alkane (generic). 721.10163 Section...Substances § 721.10163 Chloro fluoro alkane (generic). (a) Chemical substance...identified generically as chloro fluoro alkane (PMN P-08-33) is subject to...

2013-07-01

61

40 CFR 721.535 - Halogenated alkane (generic).  

Code of Federal Regulations, 2013 CFR

... 2013-07-01 false Halogenated alkane (generic). 721.535 Section 721...Substances § 721.535 Halogenated alkane (generic). (a) Chemical substance...substance identified generically as halogenated alkane (PMN P-01-433) is subject to...

2013-07-01

62

40 CFR 721.535 - Halogenated alkane (generic).  

Code of Federal Regulations, 2010 CFR

... 2010-07-01 false Halogenated alkane (generic). 721.535 Section 721...Substances § 721.535 Halogenated alkane (generic). (a) Chemical substance...substance identified generically as halogenated alkane (PMN P-01-433) is subject to...

2010-07-01

63

40 CFR 721.535 - Halogenated alkane (generic).  

Code of Federal Regulations, 2012 CFR

... 2012-07-01 false Halogenated alkane (generic). 721.535 Section 721...Substances § 721.535 Halogenated alkane (generic). (a) Chemical substance...substance identified generically as halogenated alkane (PMN P-01-433) is subject to...

2012-07-01

64

40 CFR 721.535 - Halogenated alkane (generic).  

Code of Federal Regulations, 2011 CFR

... 2011-07-01 false Halogenated alkane (generic). 721.535 Section 721...Substances § 721.535 Halogenated alkane (generic). (a) Chemical substance...substance identified generically as halogenated alkane (PMN P-01-433) is subject to...

2011-07-01

65

Millisecond Oxidation of Alkanes  

SciTech Connect

This project was undertaken in response to the Department of Energy's call to research and develop technologies 'that will reduce energy consumption, enhance economic competitiveness, and reduce environmental impacts of the domestic chemical industry.' The current technology at the time for producing 140 billion pounds per year of propylene from naphtha and Liquified Petroleum Gas (LPG) relied on energy- and capital-intensive steam crackers and Fluidized Catalytic Cracking (FCC) units. The propylene is isolated from the product stream in a costly separation step and subsequently converted to acrylic acid and other derivatives in separate production facilities. This project proposed a Short Contact Time Reactor (SCTR)-based catalytic oxydehydrogenation process that could convert propane to propylene and acrylic acid in a cost-effective and energy-efficient fashion. Full implementation of this technology could lead to sizeable energy, economic and environmental benefits for the U. S. chemical industry by providing up to 45 trillion BTUs/year, cost savings of $1.8 billion/year and a combined 35 million pounds/year reduction in environmental pollutants such as COx, NOx, and SOx. Midway through the project term, the program directive changed, which approval from the DOE and its review panel, from direct propane oxidation to acrylic acid at millisecond contact times to a two-step process for making acrylic acid from propane. The first step was the primary focus, namely the conversion of propane to propylene in high yields assisted by the presence of CO2. The product stream from step one was then to be fed directly into a commercially practiced propylene-to-acrylic acid tandem reactor system.

Scott Han

2011-09-30

66

Chemical Analog-to-Digital Signal Conversion Based on Robust Threshold Chemistry and Its Evaluation in the Context of Microfluidics-Based Quantitative Assays  

PubMed Central

In this paper, we describe a nonlinear threshold chemistry based on enzymatic inhibition and demonstrate how it can be coupled with microfluidics to convert a chemical concentration (analog input) into patterns of ON or OFF reaction outcomes (chemical digital readout). Quantification of small changes in concentration is needed in a number of assays, such as that for cystatin C, where a 1.5-fold increase in concentration may indicate the presence of acute kidney injury or the progression of chronic kidney disease. We developed an analog-to-digital chemical signal conversion that gives visual readout and applied it to an assay for cystatin C as a model target. The threshold chemistry is based on enzymatic inhibition and gives sharper responses with tighter inhibition. The chemistry described here uses acetylcholinesterase (AChE) and produces an unambiguous color change when the input is above a pre-determined threshold concentration. An input gives a pattern of ON/OFF responses when subjected to a monotonic sequence of threshold concentrations, revealing the input concentration at the point of transition from OFF to ON outcomes. We demonstrated that this threshold chemistry can detect a 1.30–fold increase in concentration at 22 °C, and that it is robust to experimental fluctuations: it provided the same output despite changes in temperature (22–34 °C) and readout time (10-fold range). We applied this threshold chemistry to diagnostics by coupling it with a traditional sandwich immunoassay for serum cystatin C. Because one quantitative measurement comprises several assays, each with its own threshold concentration, we used a microfluidic SlipChip device to process 12 assays in parallel, detecting a 1.5-fold increase (0.64 mg/L (49 nM) to 0.96 mg/L (74 nM)) of cystatin C in serum. We also demonstrated applicability to analysis of patient serum samples and the ability to image results using a cell phone camera. This work indicates that combining developments in nonlinear chemistries with microfluidics may lead to the development of user-friendly diagnostic assays with simple readouts. PMID:24060606

Huynh, Toan; Sun, Bing; Li, Liang; Nichols, Kevin P.; Koyner, Jay L.; Ismagilov, Rustem F.

2013-01-01

67

Microsomal preparation from an animal tissue catalyzes release of carbon monoxide from a fatty aldehyde to generate an alkane.  

PubMed

Alkanes are widely distributed in nature and impaired alkane synthesis was implicated in certain neurological disorders. However, the mechanism of synthesis of alkanes in animals is unknown. Our search to find a convenient animal tissue to study alkane biosynthesis resulted in the finding that the uropygial gland (a modified sebaceous gland) of the eared grebe (Podiceps nigricollis) produces large amounts of alkanes. These alkanes, which constitute 35-41% of the total lipid produced, are mainly C21, C23, C25, and C27 n-alkanes. Cell free homogenates of this tissue synthesized alkanes from both fatty acid and aldehyde in the absence of O2. Differential centrifugation of the homogenates indicated that this activity was located in the microsomal fraction. With isolated microsomes conversion of fatty acid to alkane required CoA, ATP, and NADH whereas conversion of an aldehyde to alkane did not require the addition of cofactors. That the final step in alkane synthesis is a decarbonylation was shown by the stoichiometric production of heptadecane and CO from octadecanal. CO was identified by adsorption to RhCl [(C6H6)3P]3 and oxidation of the trapped CO to CO2 by watergas shift reaction. The enzyme preparation also catalyzed incorporation of 14C from 14CO into octadecanal showing the reversible nature of the decarbonylase. This decarbonylase had a sharp pH optimum at 7.0, a Kapp of 180 microM and a V1/2 of 90 rho mol/min/mg protein for octadecanal. The enzyme was inhibited by the metal chelators EDTA, O-phenanthroline, and 8-hydroxyquinoline, but not by KCN. It was stimulated nearly 3-fold by 5 microM 2-mercaptoethanol and inhibited by the presence of O2. During the conversion of [1-3H]octadecanal to heptadecane, 3H was lost to water and 3H from 3H2O was incorporated into the alkane generated from unlabeled octadecanal. The mechanism of the decarbonylation and the nature of the enzyme remain to be elucidated. PMID:3343228

Cheesbrough, T M; Kolattukudy, P E

1988-02-25

68

Exploratory study of coal-conversion chemistry. Quarterly report No. 9, March 20, 1980-June 19, 1980. [Hydroxydiphenylmethane, diphenylether, diphenymethane  

SciTech Connect

This report describes work accomplished under two tasks: Task A, Mechanism of Cleavage of Key Bond Types Present in Coals, and Task B, Catalysis of Conversion in CO-H/sub 2/O Systems. Under Task A, the very effective catalysis of carbon-carbon bond cleavage by iron oxides in hydroxydiphenylmethane structures has been further characterized. An electron-transfer mechanism offers the most likely explanation of the observations that (1) alumina and silica-alumina surfaces are less active catalysts than Fe/sub 3/O/sub 4/, (2) meta-hydroxydiphenylmethane is almost as subject to catalysis as para-hydroxydiphenylmethane, (3) diphenyl ether is less subject to Fe/sub 3/O/sub 4/ catalysis than diphenylmethane, and (4) ortho-methoxydiphenylmethane exhibits the same susceptibility to Fe/sub 3/O/sub 4/ catalysis as ortho-hydroxydiphenylmethane. Under Task B, this quarter we have completed the survey of possible metal catalysts present in the Hastelloy C autoclave. We have found that coal conversion in CO-H/sub 2/O systems is effective when metal oxides such as MoO/sub 4//sup =/, Cr/sub 2/O/sub 7//sup =/, and MnO/sub 4//sup -/ are used as catalysts, but there is less or no coal conversion with FeCl/sub 3/ or Ni(CH/sub 3/COO)/sub 2/. While studying the fate of the catalyst after the reaction, we have isolated formate in the water-soluble fraction. This important information could help us in studying the role of formate in coal conversion. During this quarter, we have also studied the influence of reaction time and fresh CO on coal conversion in the presence of a catalyst. A striking result of 67% of benzene-soluble materials was obtained with an equivalent of 6000 ppM of Cr as sodium dichromate.

Not Available

1980-11-19

69

Methane Conversion: a Case Study for Simplification of Plasma Chemistry Models by the Omission of Charged Species  

Microsoft Academic Search

In this study the possibility of the simplification of plasma chemistry models was investigated in methane thermal plasma.\\u000a Although, ionic species and electrons are important compounds of plasmas, their concentrations are much lower than of the\\u000a neutral species. The role of non-neutral species, ions and electrons was investigated for a 1 v% methane–99 v% argon mixture\\u000a by comparing the model

Tamás Kovács

2010-01-01

70

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

SciTech Connect

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.

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

2006-01-01

71

Gas-phase reactions of the bare Th2+ and U2+ ions with small alkanes, CH4, C2H6, and C3H8: experimental and theoretical study of elementary organoactinide chemistry.  

PubMed

The gas-phase reactions of two dipositive actinide ions, Th(2+) and U(2+), with CH(4), C(2)H(6), and C(3)H(8) were studied by both experiment and theory. Fourier transform ion cyclotron resonance mass spectrometry was employed to study the bimolecular ion-molecule reactions; the potential energy profiles (PEPs) for the reactions, both observed and nonobserved, were computed by density functional theory (DFT). The experiments revealed that Th(2+) reacts with all three alkanes, including CH(4) to produce ThCH(2)(2+), whereas U(2+) reacts with C(2)H(6) and C(3)H(8), with different product distributions than for Th(2+). The comparative reactivities of Th(2+) and U(2+) toward CH(4) are well explained by the computed PEPs. The PEPs for the reactions with C(2)H(6) effectively rationalize the observed reaction products, ThC(2)H(2)(2+) and UC(2)H(4)(2+). For C(3)H(8) several reaction products were experimentally observed; these and additional potential reaction pathways were computed. The DFT results for the reactions with C(3)H(8) are consistent with the observed reactions and the different products observed for Th(2+) and U(2+); however, several exothermic products which emerge from energetically favorable PEPs were not experimentally observed. The comparison between experiment and theory reveals that DFT can effectively exclude unfavorable reaction pathways, due to energetic barriers and/or endothermic products, and can predict energetic differences in similar reaction pathways for different ions. However, and not surprisingly, a simple evaluation of the PEP features is insufficient to reliably exclude energetically favorable pathways. The computed PEPs, which all proceed by insertion, were used to evaluate the relationship between the energetics of the bare Th(2+) and U(2+) ions and the energies for C-H and C-C activation. It was found that the computed energetics for insertion are entirely consistent with the empirical model which relates insertion efficiency to the energy needed to promote the An(2+) ion from its ground state to a prepared divalent state with two non-5f valence electrons (6d(2)) suitable for bond formation in C-An(2+)-H and C-An(2+)-C activated intermediates. PMID:21265548

Di Santo, Emanuela; Santos, Marta; Michelini, Maria C; Marçalo, Joaquim; Russo, Nino; Gibson, John K

2011-02-16

72

Semifluorinated alkanes — Primitive surfactants of fascinating properties  

Microsoft Academic Search

Semifluorinated alkanes (SFAs) are diblock molecules, in which two mutually immiscible moieties, namely the hydrocarbon segment and the perfluorinated segment are bound covalently. The presence of two opposing segments within one molecule makes semifluorinated alkanes a very interesting class of compounds, which show a particular behavior both in bulk and at interfaces. Their highly asymmetric structure, arising from the incompatibility

Marcin Broniatowski; Patrycja Dynarowicz-??tka

2008-01-01

73

Alkane activation on crystalline metal oxide surfaces.  

PubMed

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

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

2014-11-21

74

Alkane-Based Urethane Potting Compounds  

NASA Technical Reports Server (NTRS)

New low viscosity urethanes easily mixed, molded, and outgassed. Alkane-based urethanes resist hydrolysis and oxidation and have excellent dielectric properties. Low-viscosity alkane-based urethane prepolymer prepared by one-step reaction of either isophorone diisocyanate or methyl-bis (4-cyclohexyl isocyanate) with hydrogenated, hydroxy-terminated polybutadiene (HTPBD).

Morris, D. E.

1986-01-01

75

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

PubMed Central

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

2013-01-01

76

Origin of stability in branched alkanes.  

PubMed

The potential origins of stability in branched alkanes are investigated, paying close attention to two recent hypotheses: geminal steric repulsion and protobranching. All alkane isomers through C(6)H(14) along with heptane and octane were investigated at the MPW1B95/6-311++G(d,p) level. Their geminal steric repulsion, total steric repulsion, and orbital interactions were evaluated by using natural bond orbital analysis. All measures of steric repulsion fail to explain the stability of branched alkanes. The extra stability of branched alkanes and protobranching, in general, is tied to stabilizing geminal sigma-->sigma* delocalization, particularly of the type that involves adjacent C-C bonds and, thus, preferentially stabilizes branched alkanes. This picture is corroborated by valence bond calculations that attribute the effect to additional ionic structures (e.g., CH(3) (+) :CH(2) :CH(3) (-) and CH(3):(-) CH(2): CH(3) (+) for propane) that are not possible without protobranching. PMID:20432414

Kemnitz, Carl R; Mackey, Joel L; Loewen, Mark J; Hargrove, Julie L; Lewis, Joshua L; Hawkins, Whitney E; Nielsen, Adam F

2010-06-18

77

Exploratory study of coal-conversion chemistry. Quarterly report, June 20, 1980-September 19, 1980. [Diphenylmethane, diphenyl ether  

SciTech Connect

This report describes work accomplished under two task: Task A, Mechanism of Cleavage of Key Bond types Present in Coals, and Task B, Catalysis of Conversion in CO-H/sub 2/O Systems. Under Task A, we have made additional measurements of catalytic carbon-carbon and carbon-oxygen bond cleavage in coal-related diphenylmethane and diphenyl ether structures. The results provide further support for, but do not definitely confirm, the tentative conclusion that the highly effective iron oxide catalysts involves oxidation to radical cation species. The homogeneous scission of carbon-oxygen bonds in diphenyl ether structure has also been studied. In the Task B studies of CO-H/sub 2/O systems, we typically obtain 50% benzene-soluble product material from 20 min. reaction of beneficiated Illinois No. 6 coal. This conversion level is obtained with aqueous solutions either at a starting pH above 12.6 or in neutral solutions with water-soluble catalysts present. We have studied a number of catalysts, including the potassium or sodium salts of molybdate, chromate, manganate, and tungstate; all are effective in the 3000 to 6000 ppM range. A striking result is that sodium nitrate at 6000 ppM is as effective as the metal salts. We found that the nitrate was converted to ammonium ion; also, formate was detected in the product aqueous phase. Finally, we find that catalytic quantities of sodium formate in CO/H/sub 2/O at pH 7 are effective in the conversion. However, in a control run in N/sub 2//H/sub 2/O, with a quantity of sodium formate equivalent to twice the molar quantity of hydrogen transferred to the coal in a successful run, the coal was converted to a product totally insoluble in benzene and with a lower hydrogen content than the starting coal.

Not Available

1981-03-04

78

Supplementary Information Solubility and Molecular Conformations of n-Alkane  

E-print Network

Supplementary Information Solubility and Molecular Conformations of n-Alkane Chains in Water Andrew's constant in aqueous solution for n-alkanes at 298K and 1 bar. (a) Logarithm of the dimensionless n-alkane to a phase change. (b) Logarithm of the dimensionless Henry's constant, , for n-alkanes in water at 298K

Ferguson, Andrew

79

DETERMINATION OF THE PRESENCE OF THE CATABOLIC ALKANE MONOOXYGENASE  

E-print Network

1 DETERMINATION OF THE PRESENCE OF THE CATABOLIC ALKANE MONOOXYGENASE GENE FROM SOIL MICROORGANISMS) for the presence of the alkane hydroxylase gene, alkB. Two sets of oligonucleotide primers were designed using by an oxygenase enzyme complex (6). For short chain n-alkanes (C5 to C12), an alkane monooxygenase enzyme begins

Moline, Mark

80

Highly Regioselective Amination of Unactivated Alkanes by Hypervalent  

E-print Network

Highly Regioselective Amination of Unactivated Alkanes by Hypervalent Sulfonylimino-3-Bromane 1 Observed rate constants kobs the concentration of alkane. The slope afforded the second constant of H-alkane kD : rate constant of D- alkane The C-D bond strength is taken to be 0.9 kcal

Katsumoto, Shingo

81

New Perspectives for light alkanes isomerization. Robert Hubaut*  

E-print Network

1 New Perspectives for light alkanes isomerization. Robert Hubaut* , Alain Rives, Wenxing Kuang number: 33/320436561 E-mail address: Robert.Hubaut@univ-lille1.fr Running title: n-alkane isomerization (2005) 101" #12;2 Abstract Isomerization of n-alkane into the high-octane number branched alkanes

Paris-Sud XI, Université de

82

Supported organoiridium catalysts for alkane dehydrogenation  

DOEpatents

Solid supported organoiridium catalysts, a process for preparing such solid supported organoiridium catalysts, and the use of such solid supported organoiridium catalysts in dehydrogenation reactions of alkanes is provided. The catalysts can be easily recovered and recycled.

Baker, R. Thomas; Sattelberger, Alfred P.; Li, Hongbo

2013-09-03

83

Hydrogen isotopic compositions, distributions and source signals of individual n -alkanes for some typical crude oils in Lunnan Oilfield, Tarim Basin, NW China  

Microsoft Academic Search

Isotopic compositions of carbon-bound hydrogen in individual n-alkanes from several typical crude oil samples from Lunnan Oilfield, Tarim Basin, NW China, were firstly measured using newly\\u000a developed gas chromatography-thermal conversion-isotope ratio mass spectrometry. The similar range of ? D of individual n-alkanes of crude oils among reservoirs of different geological times reflects that hydrocarbons are all derived from the\\u000a same

Hong Lu; Chao Li; Yongge Sun; Ping’an Peng; Zhongyao Xiao

2005-01-01

84

Gas-phase study of Fe sup + -benzyne with alkanes  

SciTech Connect

The unimolecular chemistry of Fe{sup +}-benzyne and its reactivity with small alkanes in the gas phase are studied by Fourier transform mass spectrometry (FTMS). Collision-induced dissociation of Fe{sup +}-benzyne yields benzyne loss exclusively. In contrast, photodissociation of Fe{sup +}-benzyne yields not only cleavage of benzyne from Fe{sup +}, but competitive loss of C{sub 2}H{sub 2} and C{sub 4}H{sub 2} as well. The Fe{sup +}-benzyne is formed from chlorobenzene by loss of HCl. This dehydrochlorination of chlorobenzene also occurs in secondary reactions up to six times forming products of the type Fe{sup +}-polyphenylene. Fe{sup +}-benzyne reacts with alkanes larger than methane to form a wide variety of product ions by mechanisms including hydrogenation and methanation of the benzyne ligand. All of the product ions can be explained by mechanisms based on Fe{sup +} insertion into either C-C or C-H bonds as the reaction-initiating step, followed by either alkyl or H migration from Fe{sup +} onto the benzyne ligand or, alternatively, by the migratory insertion of benzyne into a metal-carbon or metal-hydrogen bond. Photodissociation and ion-molecule reaction studies yield a value for the metal-ligand bond energy of D{degree} (Fe{sup +}-benzyne) = 76 {plus minus} 10 kcal/mol.

Yongqing Huang; Freiser, B.S. (Purdue Univ., West Lafayette, IN (USA))

1989-03-29

85

Structural insights into diversity and n-alkane biodegradation mechanisms of alkane hydroxylases  

PubMed Central

Environmental microbes utilize four degradation pathways for the oxidation of n-alkanes. Although the enzymes degrading n-alkanes in different microbes may vary, enzymes functioning in the first step in the aerobic degradation of alkanes all belong to the alkane hydroxylases. Alkane hydroxylases are a class of enzymes that insert oxygen atoms derived from molecular oxygen into different sites of the alkane terminus (or termini) depending on the type of enzymes. In this review, we summarize the different types of alkane hydroxylases, their degrading steps, and compare typical enzymes from various classes with regard to their three-dimensional structures, in order to provide insights into how the enzymes mediate their different roles in the degradation of n-alkanes and what determines their different substrate ranges. Through the above analyzes, the degrading mechanisms of enzymes can be elucidated and molecular biological methods can be utilized to expand their catalytic roles in the petrochemical industry or in bioremediation of oil-contaminated environments. PMID:23519435

Ji, Yurui; Mao, Guannan; Wang, Yingying; Bartlam, Mark

2013-01-01

86

Hydrogen isotope fractionation of low molecular weight n-alkanes during progressive vaporization  

Microsoft Academic Search

We determined the stable hydrogen isotope fractionation during progressive vaporization of three n-alkanes (heptane or C7, octane or C8, nonane or C9) at 24±1 °C, in an effort to understand the environmental isotopic fractionation of low molecular weight petroleum hydrocarbons. The measurements were carried out using continuous flow gas chromatography- high temperature conversion–isotope ratio mass spectrometry (GC\\/TC\\/IRMS). During the course of

Yi Wang; Yongsong Huang

2001-01-01

87

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

NASA Technical Reports Server (NTRS)

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

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

2014-01-01

88

Removal of chlorinated and non-chlorinated alkanes in a trickle-bed biofilter  

SciTech Connect

Industrial emissions of air contaminated with low levels of volatile organic components (VOCs) continue to be a problem, and the potential for biotreatment of these gases has resulted in an increased interest in this area. This paper describes the use of a trickle-bed reactor seeded with a microbial consortium enriched from a methanotrophic culture. The microbial consortium has been found to degrade chlorinated alkanes in air as the sole carbon source. Degradation rates of alkane mixtures are presented for the trickle-bed as well as results from batch cultures experiments designed to study degradation of various chlorinated and non-chlorinated VOCs. In batch reactors it was found that this particular consortium was capable of degrading straight C2-C5 alkanes as well as 1-chloropentane. The results indicate that chloropentane was degraded with stoichiometric release of chloride ions. It was also shown that the conversion of straight and branched alkanes in a trickle-bed reactor was temperature dependent, indicating a kinetically confined removal efficiency.

Klasson, K.T.; Davison, B.H.; Barton, J.W.; Jacobs, J.E. [Oak Ridge National Lab., TN (United States)

1998-12-31

89

Positronium bubble in liquid alkanes and alcohols  

NASA Astrophysics Data System (ADS)

Ortho-positronium (o-Ps) lifetime in alkanes and alcohols was measured in a broad range of temperatures and the results were compared with calculations in the framework of a standard bubble model. The lifetimes as a function of temperature above the melting point are almost identical for all alkanes. Assuming the potential well depth of 1 eV, the best fit of a model curve to the experimental data is obtained for surface tension increased by factor of about 1.4-1.6 comparing to flat surface. If the well depth is larger, this correcting coefficient should be larger too. The difference of decay constants in alcohol and alkane of the same chain length at a given surface tension is small; it can be ascribed to the traces of radiation chemical reactions, or to nonequal potential well depths.

Zgardzi?ska, Bozena; Goworek, Tomasz

2012-09-01

90

In situ detection of anaerobic alkane metabolites in subsurface environments.  

PubMed

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

Agrawal, Akhil; Gieg, Lisa M

2013-01-01

91

40 CFR 721.536 - Halogenated phenyl alkane.  

Code of Federal Regulations, 2011 CFR

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

2011-07-01

92

40 CFR 721.536 - Halogenated phenyl alkane.  

Code of Federal Regulations, 2012 CFR

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

2012-07-01

93

40 CFR 721.3435 - Butoxy-substituted ether alkane.  

Code of Federal Regulations, 2013 CFR

...2013-07-01 false Butoxy-substituted ether alkane. 721.3435 Section 721.3435 ...721.3435 Butoxy-substituted ether alkane. (a) Chemical substance and significant...generically as butoxy-substituted ether alkane (PMN P-92-755) is subject to...

2013-07-01

94

40 CFR 721.10704 - Aryl-substituted alkane.  

Code of Federal Regulations, 2014 CFR

...2014-07-01 false Aryl-substituted alkane. 721.10704 Section 721.10704...Substances § 721.10704 Aryl-substituted alkane. (a) Chemical substance and significant...identified generically as an aryl-substituted alkane (PMN P-12-548) is subject to...

2014-07-01

95

40 CFR 721.536 - Halogenated phenyl alkane.  

Code of Federal Regulations, 2013 CFR

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

2013-07-01

96

40 CFR 721.3435 - Butoxy-substituted ether alkane.  

Code of Federal Regulations, 2012 CFR

...2012-07-01 false Butoxy-substituted ether alkane. 721.3435 Section 721.3435 ...721.3435 Butoxy-substituted ether alkane. (a) Chemical substance and significant...generically as butoxy-substituted ether alkane (PMN P-92-755) is subject to...

2012-07-01

97

40 CFR 721.536 - Halogenated phenyl alkane.  

Code of Federal Regulations, 2010 CFR

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

2010-07-01

98

40 CFR 721.536 - Halogenated phenyl alkane.  

Code of Federal Regulations, 2014 CFR

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

2014-07-01

99

40 CFR 721.3435 - Butoxy-substituted ether alkane.  

Code of Federal Regulations, 2014 CFR

...2014-07-01 false Butoxy-substituted ether alkane. 721.3435 Section 721.3435 ...721.3435 Butoxy-substituted ether alkane. (a) Chemical substance and significant...generically as butoxy-substituted ether alkane (PMN P-92-755) is subject to...

2014-07-01

100

40 CFR 721.3435 - Butoxy-substituted ether alkane.  

Code of Federal Regulations, 2010 CFR

...2010-07-01 false Butoxy-substituted ether alkane. 721.3435 Section 721.3435 ...721.3435 Butoxy-substituted ether alkane. (a) Chemical substance and significant...generically as butoxy-substituted ether alkane (PMN P-92-755) is subject to...

2010-07-01

101

40 CFR 721.3435 - Butoxy-substituted ether alkane.  

Code of Federal Regulations, 2011 CFR

...2011-07-01 false Butoxy-substituted ether alkane. 721.3435 Section 721.3435 ...721.3435 Butoxy-substituted ether alkane. (a) Chemical substance and significant...generically as butoxy-substituted ether alkane (PMN P-92-755) is subject to...

2011-07-01

102

Microbial production of short-chain alkanes.  

PubMed

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

Choi, Yong Jun; Lee, Sang Yup

2013-10-24

103

4,5,9/99 Neuman Chapter 21 Organic Chemistry  

E-print Network

4,5,9/99 Neuman Chapter 21 0 Chapter 21 Lipids from Organic Chemistry by Robert C. Neuman, Jr. Professor of Chemistry, emeritus University of California, Riverside orgchembyneuman@yahoo.com ************************************************************************************** I. Foundations 1. Organic Molecules and Chemical Bonding 2. Alkanes and Cycloalkanes 3. Haloalkanes

Reed, Christopher A.

104

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

SciTech Connect

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.

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

105

Determination of absolute photoionization cross-sections of alkanes and cyclo-alkanes.  

PubMed

Absolute photoionization and dissociative photoionization cross-sections of eleven n-alkanes (n-pentane, n-hexane, n-heptane, n-nonane, n-decane, n-undecane, n-dodecane, n-tridecane, n-tetradecane, n-pentadecane and n-hexadecane), three cyclo-alkanes (cyclopentane, methylcyclohexane and trans-decahydronaphthalene) and iso-octane were measured for photon energies from the ionization thresholds to 11.5 eV. The measurements were performed with the binary-liquid-mixture method utilizing the photoionization cross-sections of benzene as a calibration standard. The ionization energies of n-alkanes and cyclo-alkanes were also calculated at the B3P86/6-31 + +G(d,p) level and by the G3B3 method. PMID:20391606

Zhou, Zhongyue; Zhang, Lidong; Xie, Mingfeng; Wang, Zhandong; Chen, Dongna; Qi, Fei

2010-05-15

106

Nitrated metalloporphyrins as catalysts for alkane oxidation  

DOEpatents

Compositions of matter comprising nitro-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 nitro groups attached thereto in meso and/or [beta]-pyrrolic positions.

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

1994-01-18

107

Nitrated metalloporphyrins as catalysts for alkane oxidation  

DOEpatents

Compositions of matter comprising nitro-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 nitro groups attached thereto in meso and/or .beta.-pyrrolic positions.

Ellis, Jr., Paul E. (Downingtown, PA); Lyons, James E. (Wallingford, PA)

1994-01-01

108

Reflectance spectroscopy of organic compounds: 1. Alkanes  

USGS Publications Warehouse

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.

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

2009-01-01

109

Nitrated metalloporphyrins as catalysts for alkane oxidation  

DOEpatents

Alkanes are oxidized by contact with oxygen-containing gas in the presence as catalyst of a metalloporphyrin in which hydrogen atoms in the porphyrin ring have been replaced with one or more nitro groups. Hydrogen atoms in the porphyrin ring may also be substituted with halogen atoms.

Ellis, Jr., Paul E. (Downingtown, PA); Lyons, James E. (Wallingford, PA)

1992-01-01

110

The long-chain alkane metabolism network of Alcanivorax dieselolei.  

PubMed

Alkane-degrading bacteria are ubiquitous in marine environments, but little is known about how alkane degradation is regulated. Here we investigate alkane sensing, chemotaxis, signal transduction, uptake and pathway regulation in Alcanivorax dieselolei. The outer membrane protein OmpS detects the presence of alkanes and triggers the expression of an alkane chemotaxis complex. The coupling protein CheW2 of the chemotaxis complex, which is induced only by long-chain (LC) alkanes, sends signals to trigger the expression of Cyo, which participates in modulating the expression of the negative regulator protein AlmR. This change in turn leads to the expression of ompT1 and almA, which drive the selective uptake and hydroxylation of LC alkanes, respectively. AlmA is confirmed as a hydroxylase of LC alkanes. Additional factors responsible for the metabolism of medium-chain-length alkanes are also identified, including CheW1, OmpT1 and OmpT2. These results provide new insights into alkane metabolism pathways from alkane sensing to degradation. PMID:25502912

Wang, Wanpeng; Shao, Zongze

2014-01-01

111

Modeling of Alkane Oxidation Using Constituents and Species  

NASA Technical Reports Server (NTRS)

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.

Bellan, Jasette; Harstad, Kenneth G.

2010-01-01

112

147Chemistry Chemistry (Chem)  

E-print Network

147Chemistry Chemistry (Chem) Bayly Foundation PROFESSORS FRANCE, PLEVA ASSOCIATE PROFESSORS ALty A student may complete only one of the majors listed in the Department of Chemistry. The major in chemistry leading to a Bachelor of Arts degree requires completion of 44 credits as follows: 1. Chemistry 111, 112

Dresden, Gregory

113

Vapor Pressures and Vaporization Enthalpies of the n-Alkanes from C31 to C38 at T ) 298.15 K by Correlation Gas Chromatography  

E-print Network

by Correlation Gas Chromatography James S. Chickos* and William Hanshaw Department of Chemistry and Biochemistry-alkanes studied previously. Since studies using correlation gas chromatography work best when the standards of correlation gas chromatography. This technique relies entirely on the use of standards in assessment

Chickos, James S.

114

Vapor Pressures and Vaporization Enthalpies of the n-Alkanes from C21 to C30 at T ) 298.15 K by Correlation Gas Chromatography  

E-print Network

by Correlation Gas Chromatography James S. Chickos* and William Hanshaw Department of Chemistry and Biochemistry of transfer from solution to the gas phase as measured by gas chromatography.3 A plot of the vaporization interest in using the larger n-alkanes as stan- dards for correlation gas chromatography measurements (c

Chickos, James S.

115

Semiconductor Nanowires and Nanotubes for Energy Conversion  

E-print Network

Engineering nanoscale phonon and photon transport for direct energy conversion.Energy Conversion by Melissa Anne Fardy Doctor of Philosophy in Chemistry with a Designated Emphasis in Nanoscale Science and Engineering

Fardy, Melissa Anne

2010-01-01

116

n Alkane oxidation by a Pseudomonas  

Microsoft Academic Search

Summary  \\u000a \\u000a \\u000a \\u000a 1. \\u000a \\u000a APseudomonas oxidizingn-alkanes adaptively was used in experiments on hexane and heptane degradation.\\u000a \\u000a \\u000a \\u000a \\u000a 2. \\u000a \\u000a The R.Q. of heptane respiration by resting heptane-adapted cells was found to be 0.62. No appreciable accumulation of products\\u000a except CO2 and H2O seems to occur.\\u000a \\u000a \\u000a \\u000a \\u000a 3. \\u000a \\u000a Alkane oxidation proceeds by oxidation of one terminal methyl group, leading to the corresponding alcohols, aldehydes and\\u000a fatty

G. J. E. Thijsse; A. C. van der Linden

1958-01-01

117

Oxidative dehydrogenation of alkanes to unsaturated hydrocarbons  

DOEpatents

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.

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

1988-10-11

118

Oxidative dehydrogenation of alkanes to unsaturated hydrocarbons  

DOEpatents

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.

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

1988-01-01

119

Integrated process for preparing a carboxylic acid from an alkane  

Microsoft Academic Search

The present invention relates to an integrated process for producing unsaturated carboxylic acids from the corresponding C.sub.2-C.sub.4 alkane. The process begins with performance of thermally integrated dehydrogenation reactions which convert a C.sub.2-C.sub.4 alkane to its corresponding C.sub.2-C.sub.4 alkene, and which involve exothermically converting a portion of an alkane to its corresponding alkene by oxidative dehydrogenation in an exothermic reaction zone,

Abraham Benderly; Nitin Chadda; Douglass Sevon

2011-01-01

120

Chemistry of Tantalum Clusters in Solution And on SiO(2) Supports: Analogies And Contrasts  

SciTech Connect

Tantalum clusters have been synthesized from Ta(CH{sub 2}Ph){sub 5} on the surface of porous fumed SiO{sub 2}. When these clusters are small, incorporating, on average, several Ta atoms, their chemistry is similar to that of molecular tantalum clusters (and other early transition-metal) clusters. For example, The Ta-Ta bonds in these small supported clusters have been characterized by extended X-ray absorption fine structure (EXAFS), IR, and UV-vis spectroscopy, being similar to those in molecular analogues. The redox reactions of the supported clusters, characterized by X-ray absorption near-edge structure, are analogous to those of early transition-metal clusters in solution. In contrast to the largest of these clusters in solution and in the solid state, those supported on SiO{sub 2} are raftlike, facilitating the substantial metal-support-oxygen bonding that is evident in the EXAFS spectra. Samples consisting of tantalum clusters on SiO{sub 2} catalyze alkane disproportionation and the conversion of methane with n-butane to give other alkanes, but catalytic properties of analogous clusters in solution have barely been explored.

Nemana, S.; Okamoto, N.L.; Browning, N.D.; Gates, B.C.

2009-06-03

121

40 CFR 721.9300 - Reaction products of substituted hydroxy-alkanes and polyalkylpolyisocyanatocarbomono- cycle.  

Code of Federal Regulations, 2012 CFR

...Reaction products of substituted hydroxy-alkanes and polyalkylpolyisocyanatocarbomono...Reaction products of substituted hydroxy-alkanes and polyalkylpolyisocyanatocarbomono...reaction products of substituted hydroxy-alkanes and polyal-...

2012-07-01

122

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

Code of Federal Regulations, 2014 CFR

... 2014-07-01 false Halogenated alkane aromatic compound (generic name...Substances § 721.785 Halogenated alkane aromatic compound (generic name...identified generically as a halogenated alkane aromatic compound (PMN...

2014-07-01

123

40 CFR 721.10148 - Acryloxy alkanoic alkane derivative with mixed metal oxides (generic).  

Code of Federal Regulations, 2012 CFR

...2012-07-01 false Acryloxy alkanoic alkane derivative with mixed metal oxides (generic...Substances § 721.10148 Acryloxy alkanoic alkane derivative with mixed metal oxides (generic...identified generically as acryloxy alkanoic alkane derivative with mixed metal...

2012-07-01

124

40 CFR 721.9300 - Reaction products of substituted hydroxy-alkanes and polyalkylpolyisocyanatocarbomono- cycle.  

Code of Federal Regulations, 2014 CFR

...Reaction products of substituted hydroxy-alkanes and polyalkylpolyisocyanatocarbomono...Reaction products of substituted hydroxy-alkanes and polyalkylpolyisocyanatocarbomono...reaction products of substituted hydroxy-alkanes and polyal-...

2014-07-01

125

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

Code of Federal Regulations, 2013 CFR

... 2013-07-01 false Halogenated alkane aromatic compound (generic name...Substances § 721.785 Halogenated alkane aromatic compound (generic name...identified generically as a halogenated alkane aromatic compound (PMN...

2013-07-01

126

40 CFR 721.9300 - Reaction products of substituted hydroxy-alkanes and polyalkylpolyisocyanatocarbomono- cycle.  

Code of Federal Regulations, 2010 CFR

...Reaction products of substituted hydroxy-alkanes and polyalkylpolyisocyanatocarbomono...Reaction products of substituted hydroxy-alkanes and polyalkylpolyisocyanatocarbomono...reaction products of substituted hydroxy-alkanes and polyal-...

2010-07-01

127

40 CFR 721.4464 - Mixture of hydrofluoro alkanes and hydrofluoro alkene.  

Code of Federal Regulations, 2012 CFR

...2012-07-01 false Mixture of hydrofluoro alkanes and hydrofluoro alkene. 721.4464... § 721.4464 Mixture of hydrofluoro alkanes and hydrofluoro alkene. (a) Chemical...generically as a mixture of hydrofluoro alkanes and hydrofluoro alkene (PMNs...

2012-07-01

128

40 CFR 721.10148 - Acryloxy alkanoic alkane derivative with mixed metal oxides (generic).  

Code of Federal Regulations, 2010 CFR

...2010-07-01 false Acryloxy alkanoic alkane derivative with mixed metal oxides (generic...Substances § 721.10148 Acryloxy alkanoic alkane derivative with mixed metal oxides (generic...identified generically as acryloxy alkanoic alkane derivative with mixed metal...

2010-07-01

129

Development of a Polarizable Intermolecular Potential Function (PIPF) for Liquid Amides and Alkanes  

E-print Network

Development of a Polarizable Intermolecular Potential Function (PIPF) for Liquid Amides and Alkanes inter- acting dipole (TID) polarization model has been developed for liquid alkanes and amides provides an adequate description of structural and thermodynamic prop- erties for liquid alkanes

Minnesota, University of

130

40 CFR 721.4464 - Mixture of hydrofluoro alkanes and hydrofluoro alkene.  

Code of Federal Regulations, 2010 CFR

...2010-07-01 false Mixture of hydrofluoro alkanes and hydrofluoro alkene. 721.4464... § 721.4464 Mixture of hydrofluoro alkanes and hydrofluoro alkene. (a) Chemical...generically as a mixture of hydrofluoro alkanes and hydrofluoro alkene (PMNs...

2010-07-01

131

40 CFR 721.9300 - Reaction products of substituted hydroxy-alkanes and polyalkylpolyisocyanatocarbomono- cycle.  

Code of Federal Regulations, 2011 CFR

...Reaction products of substituted hydroxy-alkanes and polyalkylpolyisocyanatocarbomono...Reaction products of substituted hydroxy-alkanes and polyalkylpolyisocyanatocarbomono...reaction products of substituted hydroxy-alkanes and polyal-...

2011-07-01

132

40 CFR 721.4464 - Mixture of hydrofluoro alkanes and hydrofluoro alkene.  

Code of Federal Regulations, 2013 CFR

...2013-07-01 false Mixture of hydrofluoro alkanes and hydrofluoro alkene. 721.4464... § 721.4464 Mixture of hydrofluoro alkanes and hydrofluoro alkene. (a) Chemical...generically as a mixture of hydrofluoro alkanes and hydrofluoro alkene (PMNs...

2013-07-01

133

40 CFR 721.10148 - Acryloxy alkanoic alkane derivative with mixed metal oxides (generic).  

Code of Federal Regulations, 2011 CFR

...2011-07-01 false Acryloxy alkanoic alkane derivative with mixed metal oxides (generic...Substances § 721.10148 Acryloxy alkanoic alkane derivative with mixed metal oxides (generic...identified generically as acryloxy alkanoic alkane derivative with mixed metal...

2011-07-01

134

40 CFR 721.10148 - Acryloxy alkanoic alkane derivative with mixed metal oxides (generic).  

Code of Federal Regulations, 2014 CFR

...2014-07-01 false Acryloxy alkanoic alkane derivative with mixed metal oxides (generic...Substances § 721.10148 Acryloxy alkanoic alkane derivative with mixed metal oxides (generic...identified generically as acryloxy alkanoic alkane derivative with mixed metal...

2014-07-01

135

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

Code of Federal Regulations, 2011 CFR

... 2011-07-01 false Halogenated alkane aromatic compound (generic name...Substances § 721.785 Halogenated alkane aromatic compound (generic name...identified generically as a halogenated alkane aromatic compound (PMN...

2011-07-01

136

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

Code of Federal Regulations, 2010 CFR

... 2010-07-01 false Halogenated alkane aromatic compound (generic name...Substances § 721.785 Halogenated alkane aromatic compound (generic name...identified generically as a halogenated alkane aromatic compound (PMN...

2010-07-01

137

40 CFR 721.4464 - Mixture of hydrofluoro alkanes and hydrofluoro alkene.  

Code of Federal Regulations, 2014 CFR

...2014-07-01 false Mixture of hydrofluoro alkanes and hydrofluoro alkene. 721.4464... § 721.4464 Mixture of hydrofluoro alkanes and hydrofluoro alkene. (a) Chemical...generically as a mixture of hydrofluoro alkanes and hydrofluoro alkene (PMNs...

2014-07-01

138

40 CFR 721.9300 - Reaction products of substituted hydroxy-alkanes and polyalkylpolyisocyanatocarbomono- cycle.  

Code of Federal Regulations, 2013 CFR

...Reaction products of substituted hydroxy-alkanes and polyalkylpolyisocyanatocarbomono...Reaction products of substituted hydroxy-alkanes and polyalkylpolyisocyanatocarbomono...reaction products of substituted hydroxy-alkanes and polyal-...

2013-07-01

139

Diffusion of an alkane molecule in siliceous zeolite beta Matthew Aronson  

E-print Network

1 Diffusion of an alkane molecule in siliceous zeolite beta Matthew was performed to study the diffusion of an alkane molecule in siliceous zeolite beta, as a function of chain length and temperature. The alkane was modeled

Shell, M. Scott

140

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

Code of Federal Regulations, 2012 CFR

... 2012-07-01 false Halogenated alkane aromatic compound (generic name...Substances § 721.785 Halogenated alkane aromatic compound (generic name...identified generically as a halogenated alkane aromatic compound (PMN...

2012-07-01

141

40 CFR 721.10148 - Acryloxy alkanoic alkane derivative with mixed metal oxides (generic).  

Code of Federal Regulations, 2013 CFR

...2013-07-01 false Acryloxy alkanoic alkane derivative with mixed metal oxides (generic...Substances § 721.10148 Acryloxy alkanoic alkane derivative with mixed metal oxides (generic...identified generically as acryloxy alkanoic alkane derivative with mixed metal...

2013-07-01

142

40 CFR 721.4464 - Mixture of hydrofluoro alkanes and hydrofluoro alkene.  

Code of Federal Regulations, 2011 CFR

...2011-07-01 false Mixture of hydrofluoro alkanes and hydrofluoro alkene. 721.4464... § 721.4464 Mixture of hydrofluoro alkanes and hydrofluoro alkene. (a) Chemical...generically as a mixture of hydrofluoro alkanes and hydrofluoro alkene (PMNs...

2011-07-01

143

Chemistry 321 Organic Chemistry  

E-print Network

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 of Organic Chemistry 7th Ed. by John McMurry. The course will focus on the bonding, stability, and shapes

Wagner, Diane

144

CHEMISTRY 11500 General Chemistry  

E-print Network

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

Jiang, Wen

145

Structural and Kinetic Studies of Novel Cytochrome P450 Small-Alkane Hydroxylases  

SciTech Connect

The goals of this project are to investigate (1) the kinetics and stabilities of engineered cytochrome P450 (P450) small alkane hydroxylases and their evolutionary intermediates, (2) the structural basis for catalytic proficiency on small alkanes of these engineered P450s, and (3) the changes in redox control resulting from protein engineering. To reach these goals, we have established new methods for determining the kinetics and stabilities of multicomponent P450s such as CYP153A6. Using these, we were able to determine that CYP153A6 is proficient for hydroxylation of alkanes as small as ethane, an activity that has never been observed previously in any natural P450. To elucidate the structures of the engineered P450s, we obtained x-ray diffraction data for two variants in the P450PMO (propane monooxygenase) lineage and a preliminary structure for the most evolved variant. This structure shows changes in the substrate binding regions of the enzyme and a reduction in active site volume that are consistent with the observed changes in substrate specificity from fatty acids in the native enzyme to small alkanes in P450PMO. We also constructed semi-rational designed libraries mutating only residues in the enzyme active site that in one round of mutagenesis and screening produced variants that achieved nearly half of the activity of the most evolved enzymes of the P450PMO lineage. Finally, we found that changes in redox properties of the laboratory-evolved P450 alkane hydroxylases did not reflect the improvement in their electron transfer efficiency. The heme redox potential remained constant throughout evolution, while activity increased and coupling efficiency improved from 10% to 90%. The lack of correlation between heme redox potential and enzyme activity and coupling efficiency led us to search for other enzyme properties that could be better predictors for activity towards small alkanes, specifically methane. We investigated the oxidation potential of the radical oxidants of various P450s directly using a chemical approach to generate the radical in situ. This resulted in the first report of direct methane to methanol conversion by a heme porphyrin catalyst using the soluble P450 from Mycobacterium sp, CYP153A6.

Arnold, Frances H.

2012-02-27

146

A Fundamentally Based Correlation Between Alkane Structure and Octane Number  

Microsoft Academic Search

At temperatures below about 850 K, the autoignition of alkane\\/air mixtures takes place by a degenerate chain mechanism. We postulate here that the differences in ease of autoignition between alkanes are due predominantly to the different rates at which the kinetic branching agent is formed. This process involves two successive internal hydrogen abstractions (isomerisations) in peroxy radicals and is very

C. MORLEY

1987-01-01

147

Melting of linear alkanes between swollen elastomers and solid substrates.  

PubMed

We have measured the melting and freezing behavior of linear alkanes confined between cross-linked poly(dimethylsiloxane) (PDMS) elastomers and solid sapphire substrates. Small molecules are often used as lubricants to reduce friction or as plasticizers, but very little is directly known about the migration or changes in physical properties of these small molecules at interfaces, particularly the changes in transition temperatures upon confinement. Our previous studies highlighted striking differences between the crystal structure of confined and unconfined pentadecane crystals in contact with sapphire substrates. Here, we have used surface-sensitive infrared-visible sum-frequency-generation spectroscopy (SFG) to study the melting temperatures (Tm) of alkanes in nanometer thick interfacial regions between swollen PDMS elastomers in contact with sapphire substrate. We find that confined alkanes show depression in Tm compared to the melting temperature of unconfined bulk alkanes. The depression in Tm is a function of chain length, and these differences were smallest for shorter alkanes and largest for 19 unit long alkanes. In comparison, the DSC results for swollen PDMS elastomer show a broad distribution of melting points corresponding to different sizes of crystals formed within the network. The Tm for confined alkanes has been modeled using the combination of Flory-Rehner and Gibbs-Thomson models, and the depression in Tm is related to the thickness of the confined alkanes. These findings have important implications in understanding friction and adhesion of soft elastomeric materials and also the effects of confinement between two solid materials. PMID:24004088

Nanjundiah, Kumar; Dhinojwala, Ali

2013-10-01

148

Molecular dynamics simulations of ordered alkane chains physisorbed on graphite  

E-print Network

Molecular dynamics simulations of ordered alkane chains physisorbed on graphite Reinhard Hentschke molecular axes oriented parallel to the substrate. Here we employ molecular dynamics (MD) simulations to obtain more details on the molecular order and dynamics within the alkane lamellae as a function

Peters, Achim

149

Alkanes in benthic organisms from the Buccaneer oil field  

SciTech Connect

About 200 g per day of alkanes are present in brine discharged from each of two production platforms in the Buccaneer oil field in the NW Gulf of Mexico. These alkanes disperse rapidly in the water column, so that seawater concentrations of petroleum alkanes in this region are generally very low. They can be taken up to some extent by plankton, fish, and barnacles, but the petroleum alkane concentrations in these organisms are also relatively low. The largest pool of petroleum alkanes is in the surficial sediments, where concentrations of up to 25 ppM are observed, with concentration gradients extending more than 20 m from the production platforms. Organisms are examined which are exposed to these sediments and, for comparison, other specimens from control sites around structures from which there are no discharges.

Middleditch, B.S.; Basile, B.

1980-06-01

150

Sophorolipids from Torulopsis bombicola: possible relation to alkane uptake.  

PubMed Central

Torulopsis bombicola produces extracellular sophorolipids when it is grown on water-insoluble alkanes. Sophorolipids and related model compounds, which were not themselves used for growth, were found to stimulate markedly the growth of T. bombicola on alkanes. This stimulatory effect was restricted to growth on C10 to C20 alkanes, whereas no significantly influence was observed for growth on fatty alcohols, fatty acids, glucose, or glycerol. The nonionic methyl ester of the glycolipid supported the greatest cell yield. However, a number of synthetic nonionic surfactants were unable to replace the glycolipid. When organisms were grown on hexadecane, stimulation of growth by sophorolipids was observed almost exclusively with strains of Torulopsis yeasts. In contrast, the growth of other typical alkane-utilizing yeasts, such as candida and Pichia strains, was inhibited or not affected. It appears that sophorolipids are involved in alkane dissimilation by T. bombicola through an undetermined mechanism. PMID:7201782

Ito, S; Inoue, S

1982-01-01

151

Thermal conductivity of liquid n-alkanes  

SciTech Connect

The thermal conductivity of liquids has been shown in the past to be difficult to predict with a reasonable accuracy, due to the lack of accurate experimental data and reliable prediction schemes. However, data of a high accuracy, and covering wide density ranges, obtained recently in laboratories in Boulder, Lisbon, and London with the transient hot-wire technique, can be used to revise an existing correlation scheme and to develop a new universal predictive technique for the thermal conductivity of liquid normal alkanes. The proposed correlation scheme is constructed on a theoretically based treatment of the van der Waals model of a liquid, which permits the prediction of the density dependence and the thermal conductivity of liquid n-alkanes, methane to tridecane, for temperatures between 110 and 370 K and pressures up to 0.6 MPa, i.e., for 0.3 less than or equal to T/T/sub c/ less than or equal to 0.7 and 2.4 less than or equal to rho/rho/sub c/ less than or equal to 3.7, with an accuracy of +/-1%, given a known value of the thermal conductivity of the fluid at the desired temperature. A generalization of the hard-core volumes obtained, as a function of the number of carbon atoms, showed that it was possible to predict the thermal conductivity of pentane to tetradecane +/- 2%, without the necessity of available experimental measurements.

Calado, J.C.G.; Fareleira, J.M.N.A.; Mardolcar, U.V.; Nieto de Castro, C.A.

1988-05-01

152

Early degradation of plant alkanes in soils:1 A litterbag experiment using 13  

E-print Network

1 Early degradation of plant alkanes in soils:1 A litterbag experiment using 13 C-labelled leaves2(0)14079373918 19 Highlights:20 specific isotope composition of long-chain alkanes was modified during leaf21 decay alkanes24 long-chain alkanes may not be used as an unaltered record of plant isotope25 composition26 27

153

Theoretical Simulation of n-Alkane Cracking on Zeolites Joseph A. Swisher,,|  

E-print Network

Theoretical Simulation of n-Alkane Cracking on Zeolites Joseph A. Swisher,,| Niels Hansen,,| Theo of alkane cracking in zeolites MFI and FAU have been simulated theoretically from first principles. The apparent rate coefficient for alkane cracking was described as the product of the number of alkane

Bell, Alexis

154

One Instructor's Approach to Computer Assisted Instruction in General Chemistry.  

ERIC Educational Resources Information Center

Discusses advantages of using computer-assisted instruction in a college general chemistry course. Advantages include using programs which generate random equations with double arrows (equilibrium systems) or generate alkane structural formula, asking for the correct IUPAC name of the structure. (Author/JN)

DeLorenzo, Ronald

1982-01-01

155

Expanding the Product Profile of a Microbial Alkane Biosynthetic Pathway  

PubMed Central

Microbially produced alkanes are a new class of biofuels that closely match the chemical composition of petroleum-based fuels. Alkanes can be generated from the fatty acid biosynthetic pathway by the reduction of acyl-ACPs followed by decarbonylation of the resulting aldehydes. A current limitation of this pathway is the restricted product profile, which consists of n-alkanes of 13, 15, and 17 carbons in length. To expand the product profile, we incorporated a new part, FabH2 from Bacillus subtilis, an enzyme known to have a broader specificity profile for fatty acid initiation than the native FabH of Escherichia coli. When provided with the appropriate substrate, the addition of FabH2 resulted in an altered alkane product profile in which significant levels of n-alkanes of 14 and 16 carbons in length are produced. The production of even chain length alkanes represents initial steps toward the expansion of this recently discovered microbial alkane production pathway to synthesize complex fuels. This work was conceived and performed as part of the 2011 University of Washington international Genetically Engineered Machines (iGEM) project. PMID:23656326

Harger, Matthew; Zheng, Lei; Moon, Austin; Ager, Casey; An, Ju Hye; Choe, Chris; Lai, Yi-Ling; Mo, Benjamin; Zong, David; Smith, Matthew D.; Egbert, Robert G.; Mills, Jeremy H.; Baker, David; Pultz, Ingrid Swanson; Siegel, Justin B.

2013-01-01

156

The vapor-particle partitioning of n-alkanes  

SciTech Connect

A mixed-phase partitioning model has been proposed to predict the distribution of n-alkanes between the vapor and particle phases in the atmosphere. n-Alkanes having terrestrial plant wax and petroleum origins are assumed to be associated with atmospheric particles as microcrystalline solids and subcooled liquids, respectively. The fraction of n-alkanes on atmospheric particles having plant wax and petroleum origins is estimated with carbon preference indices. Hypothetical terrestrial plant wax and petroleum mixtures are used to estimate the mole fractions of the n-alkanes in each phase and the molecular weights of the phases. Solid and subcooled liquid phase n-alkane vapor pressures are used in the model to predict the fraction of n-alkanes associated with particles in the atmosphere. Trends in the prediction of vapor-particle partitioning using these assumptions agree well with field observations. However, the fraction of particle phase n-alkanes predicted by the model was significantly different from the field observations.

Doskey, P.V.

1994-04-01

157

Kinetic study of asphaltene dissolution in amphiphile/alkane solutions  

SciTech Connect

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.

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

158

Alkane separation using nanoporous graphene membranes.  

PubMed

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

Nieszporek, Krzysztof; Drach, Mateusz

2015-01-14

159

DITERMINAL OXIDATION OF LONG-CHAIN ALKANES BY BACTERIA1  

PubMed Central

Kester, A. S. (The University of Texas, Austin) and J. W. Foster. Diterminal oxidation of long-chain alkanes by bacteria. J. Bacteriol. 85:859–869. 1963.—A corynebacterial organism capable of growing in mineral salts with individual pure alkanes as carbon sources produces a series of acids from the C10-C14 alkanes. They have been isolated in pure form and identified as monoic, ?-hydroxy monoic, and dioic acids containing the same number of carbon atoms as the substrate alkane. Oxidation took place at both terminal methyl groups—“diterminal oxidation.” Appropriate labeling experiments indicate that omega oxidation of fatty acids occurs in this organism and that an oxygenation with O2 occurs. Images PMID:14044955

Kester, A. S.; Foster, J. W.

1963-01-01

160

Process for converting light alkanes to higher hydrocarbons  

DOEpatents

A process is disclosed for the production of aromatic-rich, gasoline boiling range hydrocarbons from the lower alkanes, particularly from methane. The process is carried out in two stages. In the first, alkane is reacted with oxygen and hydrogen chloride over an oxyhydrochlorination catalyst such as copper chloride with minor proportions of potassium chloride and rare earth chloride. This produces an intermediate gaseous mixture containing water and chlorinated alkanes. The chlorinated alkanes are contacted with a crystalline aluminosilicate catalyst in the hydrogen or metal promoted form to produce gasoline range hydrocarbons with a high proportion of aromatics and a small percentage of light hydrocarbons (C.sub.2 -C.sub.4). The light hydrocarbons can be recycled for further processing over the oxyhydrochlorination catalyst.

Noceti, Richard P. (Pittsburgh, PA); Taylor, Charles E. (Pittsburgh, PA)

1988-01-01

161

At what chain length do unbranched alkanes prefer folded conformations?  

E-print Network

Short unbranched alkanes are known to prefer linear conformations, while long unbranched alkanes are folded. It is not known with certainty at what chain length the linear conformation is no longer the global minimum. To clarify this point, we use {\\it ab initio} and density functional methods to compute the relative energies of the linear and hairpin alkane conformers for increasing chain lengths. Extensive electronic structure calculations are performed to obtain optimized geometries, harmonic frequencies and accurate single point energies for the selected alkane conformers from octane through octadecane. Benchmark CCSD(T)/cc-pVTZ single point calculations are performed for chains through tetradecane, while approximate methods are required for the longer chains up to octadecane. Using frozen natural orbitals to unambiguously truncate the virtual orbital space we are able to compute composite CCSD FNO(T) single point energies for all the chain lengths. This approximate composite method has significant comput...

Byrd, Jason N; Montgomery, John A

2013-01-01

162

Modelling LLE and VLE of methanol + n-alkane series using GC-PC-SAFT with a group contribution k ij  

Microsoft Academic Search

The fluid phase diagrams (LLE and VLE) of methanol+n-alkane mixtures series (from C4 up to C16) were modelled using GC-PC-SAFT EOS (Tamouza et al., Fluid Phase Equilibria 222–223 (2004) 67–76) combined with a recent method for computing kij based on the London theory (NguyenHuynh et al., Industrial & Engineering Chemistry Research 47 (2008) 8847–8858). This latter method requires pure compound

M. Mourah; D. NguyenHuynh; J. P. Passarello; J. C. de Hemptinne; P. Tobaly

2010-01-01

163

Tropospheric Chemistry  

NASA Technical Reports Server (NTRS)

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.

Mohnen, V.

1984-01-01

164

An analytical approximation for high-temperature autoignition times of higher alkanes  

SciTech Connect

It is shown that, above about 1000 K, ignition delay times for propane and all higher alkanes, as well as for a number of other fuels, can be calculated well by employing rate parameters of only three types of elementary steps, namely C{sub m}H{sub n} + HO{sub 2} {yields} C{sub m}H{sub n-1} + H{sub 2}O{sub 2}, H{sub 2}O{sub 2} + M{yields}2OH + M and 2HO{sub 2} {yields} H{sub 2}O{sub 2} + O{sub 2}, only the first of which is fuel specific, the other two clearly being common to all fuels. The prediction of this remarkably simple result relies on a steady-state approximation for HO{sub 2}, as well as steady states for more active radicals during induction. The resulting approximation to the chemistry exhibits a slow, finite-rate buildup of H{sub 2}O{sub 2} and removal of fuel during the induction period. The criterion employed for termination of the induction period is the complete depletion of the original fuel subject to the approximations introduced. Numerical comparisons of the ignition-time formula with the experiments show that the predictions work well not only for higher alkanes but also for propene and JP-10. The analytical approximation thus produces reasonable results for a wide range of fuels. (author)

Saxena, P.; Peters, N.; Williams, F.A. [Center for Energy Research, Department of Mechanical and Aerospace Engineering, University of California, San Diego, 9500, Gilman Drive, Department 0411, La Jolla, CA 92093 (United States)

2007-04-15

165

Plasma processing and chemistry  

Microsoft Academic Search

Plasma deposition and plasma conversion can be characterized by five steps: pro- duction by ionization, transfer of chemistry to precursors, transport of radicals to the surface, surface interactions with deposition, recirculation and generation of new monomers. For very fast deposition, large flows of radicals are needed and a regime is reached, in which mono- layer coverage is reached in a

Daniel C. Schram

2002-01-01

166

Plasma processing and chemistry  

Microsoft Academic Search

The growing field of applications of plasma as deposition, etching, surface modification and chemical conversion has stimulated a renewed interest in plasma science in the atomic physical chemistry regime. The necessity to optimize the various plasma processing techniques in terms of rates, and material properties has made it mandatory to take a new look at the various processes, as fragmentation,

D C Schram; J A M van der Mullen; M C M van de Sanden

1994-01-01

167

University of California Organic Chemistry Lab  

E-print Network

02262014 University of California Berkeley CHEM N3AL Organic Chemistry Lab June 23-August 15, 2014, Discussions and Conversations to Communicate in Your Course How to Check Your Grade Organic Chemistry-lab and lab report). 1. Textbooks/Course Materials Understanding the Principles of Organic Chemistry

Walker, Matthew P.

168

University of California Organic Chemistry Lab  

E-print Network

04282014 University of California Berkeley CHEM N3AL Organic Chemistry Lab June 23-August 15, 2014 and Conversations to Communicate in Your Course How to Check Your Grade Organic Chemistry Laboratory is hybrid. Textbooks/Course Materials Understanding the Principles of Organic Chemistry, A Laboratory Experience

Jacobs, Lucia

169

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

E-print Network

148 Chemistry/Chinese Chemistry 347 (3)--Advanced Organic Chemistry Prerequisite: Chemistry 242,syntheticmethodology,mod- ernsyntheticreactions,protectinggroups,naturalprod- uctssynthesis,andcombinatorialchemistry.France. Spring Chemistry 350 (3)--Advanced Inorganic Chemistry Prerequisites: Chemistry 250, 252, and 262. Anintro

Dresden, Gregory

170

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

Code of Federal Regulations, 2013 CFR

...dihydroxy dialkyl ether, hydroxy substituted alkane and carboxylic acid anhydride, methacrylate...dihydroxy dialkyl ether, hydroxy substituted alkane and carboxylic acid anhydride, methacrylate...dihydroxy dialkyl ether, hydroxy substituted alkane and carboxylic acid anhydride,...

2013-07-01

171

40 CFR 721.10145 - Modified reaction products of alkyl alcohol, halogenated alkane, substituted epoxide, and amino...  

Code of Federal Regulations, 2012 CFR

...products of alkyl alcohol, halogenated alkane, substituted epoxide, and amino compound...products of alkyl alcohol, halogenated alkane, substituted epoxide, and amino compound...products of alkyl alcohol, halogenated alkane, substituted epoxide, and amino...

2012-07-01

172

40 CFR 721.10625 - Distillation bottoms, alkylated benzene by-product, brominated and bromo diphenyl alkane (generic).  

Code of Federal Regulations, 2013 CFR

...by-product, brominated and bromo diphenyl alkane (generic). 721.10625 Section...by-product, brominated and bromo diphenyl alkane (generic). (a) Chemical substances...by-product, brominated and bromo diphenyl alkane (PMNs P-12-332 and...

2013-07-01

173

40 CFR 721.10626 - 1,4-Butanediol, polymer with substituted alkane and substituted methylene biscarbomonocycle, 2...  

Code of Federal Regulations, 2014 CFR

...4-Butanediol, polymer with substituted alkane and substituted methylene biscarbomonocycle...4-Butanediol, polymer with substituted alkane and substituted methylene biscarbomonocycle...4-butanediol, polymer with substituted alkane and substituted methylene...

2014-07-01

174

40 CFR 721.10145 - Modified reaction products of alkyl alcohol, halogenated alkane, substituted epoxide, and amino...  

Code of Federal Regulations, 2013 CFR

...products of alkyl alcohol, halogenated alkane, substituted epoxide, and amino compound...products of alkyl alcohol, halogenated alkane, substituted epoxide, and amino compound...products of alkyl alcohol, halogenated alkane, substituted epoxide, and amino...

2013-07-01

175

40 CFR 721.10145 - Modified reaction products of alkyl alcohol, halogenated alkane, substituted epoxide, and amino...  

Code of Federal Regulations, 2010 CFR

...products of alkyl alcohol, halogenated alkane, substituted epoxide, and amino compound...products of alkyl alcohol, halogenated alkane, substituted epoxide, and amino compound...products of alkyl alcohol, halogenated alkane, substituted epoxide, and amino...

2010-07-01

176

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

Code of Federal Regulations, 2012 CFR

...dihydroxy dialkyl ether, hydroxy substituted alkane and carboxylic acid anhydride, methacrylate...dihydroxy dialkyl ether, hydroxy substituted alkane and carboxylic acid anhydride, methacrylate...dihydroxy dialkyl ether, hydroxy substituted alkane and carboxylic acid anhydride,...

2012-07-01

177

40 CFR 721.10625 - Distillation bottoms, alkylated benzene by-product, brominated and bromo diphenyl alkane (generic).  

Code of Federal Regulations, 2014 CFR

...by-product, brominated and bromo diphenyl alkane (generic). 721.10625 Section...by-product, brominated and bromo diphenyl alkane (generic). (a) Chemical substances...by-product, brominated and bromo diphenyl alkane (PMNs P-12-332 and...

2014-07-01

178

40 CFR 721.10145 - Modified reaction products of alkyl alcohol, halogenated alkane, substituted epoxide, and amino...  

Code of Federal Regulations, 2014 CFR

...products of alkyl alcohol, halogenated alkane, substituted epoxide, and amino compound...products of alkyl alcohol, halogenated alkane, substituted epoxide, and amino compound...products of alkyl alcohol, halogenated alkane, substituted epoxide, and amino...

2014-07-01

179

40 CFR 721.10145 - Modified reaction products of alkyl alcohol, halogenated alkane, substituted epoxide, and amino...  

Code of Federal Regulations, 2011 CFR

...products of alkyl alcohol, halogenated alkane, substituted epoxide, and amino compound...products of alkyl alcohol, halogenated alkane, substituted epoxide, and amino compound...products of alkyl alcohol, halogenated alkane, substituted epoxide, and amino...

2011-07-01

180

40 CFR 721.10626 - 1,4-Butanediol, polymer with substituted alkane and substituted methylene biscarbomonocycle, 2...  

Code of Federal Regulations, 2013 CFR

...4-Butanediol, polymer with substituted alkane and substituted methylene biscarbomonocycle...4-Butanediol, polymer with substituted alkane and substituted methylene biscarbomonocycle...4-butanediol, polymer with substituted alkane and substituted methylene...

2013-07-01

181

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

Code of Federal Regulations, 2014 CFR

...dihydroxy dialkyl ether, hydroxy substituted alkane and carboxylic acid anhydride, methacrylate...dihydroxy dialkyl ether, hydroxy substituted alkane and carboxylic acid anhydride, methacrylate...dihydroxy dialkyl ether, hydroxy substituted alkane and carboxylic acid anhydride,...

2014-07-01

182

Recent Advances in Catalytic Conversion of Ethanol to Chemicals  

SciTech Connect

With increased availability and decreased cost, ethanol is potentially a promising platform molecule for the production of a variety of value-added chemicals. In this review, we provide a detailed summary of recent advances in catalytic conversion of ethanol to a wide range of chemicals and fuels. We particularly focus on catalyst advances and fundamental understanding of reaction mechanisms involved in ethanol steam reforming (ESR) to produce hydrogen, ethanol conversion to hydrocarbons ranging from light olefins to longer chain alkenes/alkanes and aromatics, and ethanol conversion to other oxygenates including 1-butanol, acetaldehyde, acetone, diethyl ether, and ethyl acetate.

Sun, Junming; Wang, Yong

2014-04-30

183

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

PubMed Central

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

Callaghan, Amy V.

2013-01-01

184

Thermodynamics of alkanol-alkane mixtures  

SciTech Connect

A new theoretical approach is presented for the description of the thermodynamic behavior of systems containing associated compounds. A continuous linear association model is implemented in the lattice-fluid theory of Sanchez and Lacombe as modified recently by the author. The apparent equilibrium association constant, widely used in the various theories of associated solutions, is density dependent in the present model. The model can be applied to both liquids and gases at any external conditions down to the critical point. A single set of association enthalpy, association entropy, and association volume is used for all 1-alkanols; these association properties are pure-component properties. The theory is used to calculate vapor pressures, orthobaric densities, and heats of vaporization of 1-alkanols. New lattice-fluid scaling constants for these compounds are presented which are now close to the corresponding constants of their homomorph hydrocarbons. The theory is, subsequently, extended to mixtures and used to calculate the basic thermodynamic quantities of mixing for a number of alkanol-alkane systems. In its present form the theory is an approximate one since it does not take into account, besides others, the cooperative character of association phenomena in dilute liquid solutions and gases, but because of its simplicity it may form the basis for more refined treatments.

Panayiotou, C.G.

1988-05-19

185

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

SciTech Connect

Detailed chemical kinetic models are needed to simulate the combustion of current and future transportation fuels. These models should represent the various chemical classes in these fuels. Conventional diesel fuels are composed of n-alkanes, iso-alkanes, cycloalkanes and aromatics (Farrell et al. 2007). For future fuels, there is a renewed interest in Fischer-Tropsch (F-T) processes which can be used to synthesize diesel and other transportation fuels from biomass, coal and natural gas. F-T diesel fuels are expected to be similar to F-T jet fuels which are commonly comprised of iso-alkanes with some n-alkanes (Smith and Bruno, 2008). Thus, n-alkanes and iso-alkanes are common chemical classes in these conventional and future fuels. This paper reports on the development of chemical kinetic models of large n-alkanes and iso-alkanes to represent these chemical classes in conventional and future fuels. Two large iso-alkanes are 2,2,4,4,6,8,8-heptamethylnonane, which is a primary reference fuel for diesel, and isooctane, a primary reference fuel for gasoline. Other iso-alkanes are branched alkanes with a single methyl side chain, typical of most F-T fuels. The chemical kinetic models are then used to predict the effect of these fuel components on ignition characteristics under conditions found in internal combustion engines.

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

2008-12-15

186

Selective hydroxylation of alkanes by an extracellular fungal peroxygenase.  

PubMed

Fungal peroxygenases are novel extracellular heme-thiolate biocatalysts that are capable of catalyzing the selective monooxygenation of diverse organic compounds, using only H(2)O(2) as a cosubstrate. Little is known about the physiological role or the catalytic mechanism of these enzymes. We have found that the peroxygenase secreted by Agrocybe aegerita catalyzes the H(2)O(2)-dependent hydroxylation of linear alkanes at the 2-position and 3-position with high efficiency, as well as the regioselective monooxygenation of branched and cyclic alkanes. Experiments with n-heptane and n-octane showed that the hydroxylation proceeded with complete stereoselectivity for the (R)-enantiomer of the corresponding 3-alcohol. Investigations with a number of model substrates provided information about the route of alkane hydroxylation: (a) the hydroxylation of cyclohexane mediated by H(2)(18)(2) resulted in complete incorporation of (18)O into the hydroxyl group of the product cyclohexanol; (b) the hydroxylation of n-hexane-1,1,1,2,2,3,3-D(7) showed a large intramolecular deuterium isotope effect [(k(H)/k(D))(obs)] of 16.0 ± 1.0 for 2-hexanol and 8.9 ± 0.9 for 3-hexanol; and (c) the hydroxylation of the radical clock norcarane led to an estimated radical lifetime of 9.4 ps and an oxygen rebound rate of 1.06 × 10(11) s(-1). These results point to a hydrogen abstraction and oxygen rebound mechanism for alkane hydroxylation. The peroxygenase appeared to lack activity on long-chain alkanes (> C(16)) and highly branched alkanes (e.g. tetramethylpentane), but otherwise exhibited a broad substrate range. It may accordingly have a role in the bioconversion of natural and anthropogenic alkane-containing structures (including alkyl chains of complex biomaterials) in soils, plant litter, and wood. PMID:21812933

Peter, Sebastian; Kinne, Matthias; Wang, Xiaoshi; Ullrich, René; Kayser, Gernot; Groves, John T; Hofrichter, Martin

2011-10-01

187

Online Conversion  

NSDL National Science Digital Library

Need to convert joules to kilocalories? A rood to a square mile? 100 weight to stones? How about your age in dog years? You can do all of these conversions and over 8,000 more at Online Conversion. Conversions are organized by type (temperature, length, cooking, etc.), and each conversion page includes numerous options. Quick links to other conversions are also provided on each page so users don't have to return to the main page. Simply put, a very handy and easy-to-use site that belongs in the reference section of any user's bookmarks.

188

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

NASA Astrophysics Data System (ADS)

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.

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

2010-12-01

189

Production of renewable jet fuel range alkanes and commodity chemicals from integrated catalytic  

E-print Network

Production of renewable jet fuel range alkanes and commodity chemicals from integrated catalytic and subsequently upgrading these two platforms into a mixture of branched, linear, and cyclic alkanes of molecular

California at Riverside, University of

190

Fading MIMO Relay Channels with Channel Estimation Error Bengi Aygun Alkan Soysal  

E-print Network

Fading MIMO Relay Channels with Channel Estimation Error Bengi Ayg¨un Alkan Soysal Department.aygun@bahcesehir.edu.tr alkan.soysal@bahcesehir.edu.tr Abstract--In this paper, we consider a full-duplex, decode- and

Soysal, Alkan

191

Fading MIMO Relay Channels with Covariance Feedback Bengi Aygun Alkan Soysal  

E-print Network

Fading MIMO Relay Channels with Covariance Feedback Bengi Ayg¨un Alkan Soysal Department.aygun@bahcesehir.edu.tr alkan.soysal@bahcesehir.edu.tr Abstract--In this paper, the source and relay transmit covari- ance

Soysal, Alkan

192

SHORT COMMUNICATION Blends of (R)-3-hydroxyhexan-2-one and alkan-2-ones  

E-print Network

SHORT COMMUNICATION Blends of (R)-3-hydroxyhexan-2-one and alkan-2-ones identified as potential Cerambycinae) pro- duce the common cerambycine pheromone component (R)-3-hydroxyhexan-2-one as well as an alkan

Hanks, Lawrence M.

193

Molecular simulation study of homogeneous crystal nucleation in n-alkane melts  

E-print Network

This work used molecular dynamics (MD) and Monte Carlo (MC) method to study the homogeneous crystal nucleation in the melts of n-alkanes, the simplest class of chain molecules. Three n-alkanes with progressive chain length ...

Yi, Peng, Ph. D. Massachusetts Institute of Technology

2011-01-01

194

BIODEGRADATION AND GAS-EXCHANGE OF GASEOUS ALKANES IN MODEL ESTUARINE ECOSYSTEMS  

EPA Science Inventory

Gas exchange-biodegradation experiments conducted in model estuarine ecosystems indicate that the ease of degradation of gaseious normal alkanes increases with chain length. The behavior of gaseous perhalogenated alkanes can be explained by gas exchange alone with no degradation....

195

Biodegradation of variable-chain-length alkanes at low temperatures by a psychrotrophic Rhodococcus sp  

Microsoft Academic Search

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 5 C, Q15 mineralized the short-chain alkanes dodecane and hexadecane to a greater extent than that observed for the long-chain alkanes octacosane and dotriacontane.

LYLE G. WHYTE; JALAL HAWARI; EDWARD ZHOU; LUC BOURBONNIERE; C. W. Greer; W. E. Inniss

1998-01-01

196

Surface freezing in chain molecules: Normal alkanes B. M. Ocko,1  

E-print Network

Surface freezing in chain molecules: Normal alkanes B. M. Ocko,1 X. Z. Wu,2,3 E. B. Sirota,4 S. K October 1996 A rare surface freezing phenomenon is observed in molten normal alkanes, using x-ray and surface tension measurements. An ordered monolayer forms on the surface of the liquid alkane

Ocko, Ben

197

DOI: 10.1002/cctc.201000383 Catalytic Co-Homologation of Alkanes and Dimethyl Ether  

E-print Network

DOI: 10.1002/cctc.201000383 Catalytic Co-Homologation of Alkanes and Dimethyl Ether and Promotion reactions to form alkanes. Alkoxides can desorb as alkenes, which can undergo subse- quent methylation for the co-homologa- tion of linear and branched alkanes with dimethyl ether (DME) to form larger branched

Iglesia, Enrique

198

Synthesis and characterization of a new catalyst Pt/Mg(Ga)(Al)O for alkane dehydrogenation  

E-print Network

Synthesis and characterization of a new catalyst Pt/Mg(Ga)(Al)O for alkane dehydrogenation Pingping-promoted Pt particles for the dehydrogenation of light alkanes to alkenes. The modifying element, Ga alternative source, since the starting materials are inexpen- sive. A further attraction of alkane

Bell, Alexis

199

Nucleation in n-alkanes: A density-functional approach Chaok Seok and David W. Oxtobya)  

E-print Network

Nucleation in n-alkanes: A density-functional approach Chaok Seok and David W. Oxtobya) Department and nucleation are discussed. It is shown that the n-alkane systems cannot be well approximated by a system char- acter the alcohols , or elongated and flexible chains the n-alkanes . In order to confront theory

Seok, Chaok

200

Temperature dependence of the structure of Langmuir films of normal-alkanes on liquid mercury  

E-print Network

Temperature dependence of the structure of Langmuir films of normal-alkanes on liquid mercury H phase behavior of Langmuir films of n-alkanes CH3(CH2)n 2CH3 , denote Cn on mercury was studied surface normal, alkanes on mercury are always oriented surface parallel and show no long-range in

Ocko, Ben

201

Femtosecond IR Studies of Alkane C-H Bond Activation by Organometallic Compounds: Direct  

E-print Network

Femtosecond IR Studies of Alkane C-H Bond Activation by Organometallic Compounds: Direct alkane solution.8,9 Our recent study on this system attributes the origin of the low quantum yield-Pz3*, Pz* ) 3,5- dimethylpyrazolyl) in room temperature alkane solution. The relatively high C

Harris, Charles B.

202

Structural phase transition of alkane molecules in nanotube composites Chenyu Wei*  

E-print Network

Structural phase transition of alkane molecules in nanotube composites Chenyu Wei* NASA Ames of alkane molecules in carbon nanotube CNT composites are studied through molecular dynamics simulations transition of the alkane molecules is found with small radius armchaired CNT 5, 5 as a nucleation site, where

Wei, Chenyu

203

A Simulation Study on the Adsorption Properties of Linear Alkanes on Closed Nanotube Bundles  

E-print Network

A Simulation Study on the Adsorption Properties of Linear Alkanes on Closed Nanotube Bundles James@photon.t.u-tokyo.ac.jp KEYWORDS: Chromatography, Alkane, Nanotube bundle, Grand-canonical Monte Carlo (GCMC), Separation, Ideal properties of such bundles. The adsorption of linear alkanes, with their systematic variation through chain

Maruyama, Shigeo

204

Efficiency of direct saponification for the analysis of n-alkanes in hays  

E-print Network

Efficiency of direct saponification for the analysis of n-alkanes in hays R Ferrer, M Petit, G-Genès-Champanelle, France The use of alkanes as forage markers for diges- tive studies requires efficient and rapid methods; a semi-capillary column was used. Odd-alkanes (from C27 to C35) were only considered because

Paris-Sud XI, Université de

205

Evaporating drops of alkane mixtures G.Guna, C.Poulard, A.M.Cazabat*  

E-print Network

Evaporating drops of alkane mixtures G.Guéna, C.Poulard, A.M.Cazabat* Collège de France, 11 place: Alkane mixtures are model systems where the influence of surface tension gradients during the spreading with the substrate. The present paper is devoted to the evaporation of drops composed of binary alkane mixtures

Paris-Sud XI, Université de

206

Regio-and Enantioselective Alkane Hydroxylation with Engineered Cytochromes P450 BM-3  

E-print Network

Regio- and Enantioselective Alkane Hydroxylation with Engineered Cytochromes P450 BM-3 Matthew W alkanes regio- and enantioselectively using atmospheric dioxygen as an oxidant. BM-3 variant 9-10A-A328V alkanes larger than hexane primarily at the 2-position but forms R-2-alcohols (40-55% ee

Arnold, Frances H.

207

USING N-ALKANES TO ESTIMATE DIET COMPOSITION OF HERBIVORES: A NOVEL MATHEMATICAL APPROACH  

E-print Network

USING N-ALKANES TO ESTIMATE DIET COMPOSITION OF HERBIVORES: A NOVEL MATHEMATICAL APPROACH PAULO BARCIA, MIGUEL N. BUGALHO, MANUEL L. CAMPAGNOLO, J. ORESTES CERDEIRA Abstract. N-alkanes are long chain the diet compo- sition of herbivores. An important constraint of using N-alkanes to estimate diet

Lisboa, Universidade Técnica de

208

Surface freezing in binary alkane-alcohol mixtures E. Sloutskin,1  

E-print Network

Surface freezing in binary alkane-alcohol mixtures E. Ofer,1 E. Sloutskin,1 L. Tamam,1 B. M. Ocko,2 of alcohol and alkane molecules, using surface tensiometry and surface-specific x-ray scattering methods. Considering that surface freezing in pure alkanes forms an ordered monolayer and in alcohols it forms

Ocko, Ben

209

A coarse grain model for n-alkanes parameterized from surface tension data  

E-print Network

A coarse grain model for n-alkanes parameterized from surface tension data Steve O. Nielsen, Carlos a coarse grain model for multiple-of-three carbon n-alkanes. The procedure involves optimizing harmonic density data. Scaling relations are introduced to allow for the representation of the remaining n-alkanes

Nielsen, Steven O.

210

Temperature Effect on Pump Oil and Alkanes Evaporation Nathaniel A. Waldstein and Alex A. Volinsky  

E-print Network

Temperature Effect on Pump Oil and Alkanes Evaporation Nathaniel A. Waldstein and Alex A. Volinsky rates of pump oil and several alkanes, which have a wide range of applications. Both static and dynamic the evaporation rate). The alkanes were compared using the activation energy required for evaporation as model

Volinsky, Alex A.

211

Directed Evolution of a Cytochrome P450 Monooxygenase for Alkane Oxidation  

E-print Network

Directed Evolution of a Cytochrome P450 Monooxygenase for Alkane Oxidation Edgardo T. Farinas = slight affinity) accurately reflects the nature of these com- pounds: alkanes are notoriously inert unsaturated fatty acids.[7] The enzyme is reported to be inactive towards alkanes and methyl esters lacking

Arnold, Frances H.

212

The isotropic molecular polarizabilities of single methyl-branched alkanes in the terahertz range  

E-print Network

The isotropic molecular polarizabilities of single methyl-branched alkanes in the terahertz range the polarizabilities of methyl branched alkanes in the terahertz spectral range, and compare,10]. In particular, the n-alkanes, a homologous series of saturated hydrocarbons with the general formula CnH2n+2

Mittleman, Daniel

213

Rapid analysis of 13 C in plant-wax n-alkanes for  

E-print Network

Rapid analysis of 13 C in plant-wax n-alkanes for reconstruction of terrestrial vegetation signals, Massachusetts 02543, USA [1] Long-chain, odd-carbon-numbered C25 to C35 n-alkanes are characteristic components analyses of total plant-wax n-alkanes using a novel, moving-wire system coupled to an isotope-ratio mass

Sessions, Alex L.

214

Self-assembly of long chain alkanes and their derivatives on graphite Teng Yang,1  

E-print Network

Self-assembly of long chain alkanes and their derivatives on graphite Teng Yang,1 Savas Berber,1 initio calculations to study the self-assembly of long chain alkanes and related alcohol and carboxylic the ordering of long chain alkanes in self-assembled monolayers and ways to modify it using alcohol and acid

215

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

E-print Network

Effects of conformational isomerism on the desorption kinetics of n-alkanes from graphite Kris R surfaces have been studied by measuring the desorption kinetics of a set of n-alkanes from the surface of single crystalline graphite. Desorption rates were measured using a set of 21 monodispersed n-alkanes

Gellman, Andrew J.

216

Quantification of Hydrogen Peroxide during the Low Temperature Oxidation of Alkanes  

E-print Network

1 Quantification of Hydrogen Peroxide during the Low Temperature Oxidation of Alkanes Chiheb the autoignition. The studied hydrocarbon was nbutane, the smallest alkane which has an oxidation behavior close of hydrocarbons (5). Figure 1. Simplified scheme of the mechanism of oxidation of alkanes (dotted arrows

Paris-Sud XI, Université de

217

Unconventional adsorption of alkane substituted naphthalene diimides on highly ordered pyrolytic graphite  

E-print Network

Unconventional adsorption of alkane substituted naphthalene diimides on highly ordered pyrolytic-assembled structure of N,N'-Dialkyl-1,8:4,5-naphthalenediimides (Cn-diimide) with alkane chains of varying length (C6, C8, and C12). Many alkane substituted systems exhibit linear lamellar structures due

Collins, Gary S.

218

Nitroxide spin exchange due to re-encounter collisions in a series of n-alkanes  

E-print Network

Nitroxide spin exchange due to re-encounter collisions in a series of n-alkanes Mark R. Kurban perdeuterated 2,2,6,6-tetramethyl-4-oxopiperidine-l-oxyl molecules in three alkanes have been studied plotted with respect to compressibility. The existence of a common curve for alkanes raises the prospect

Bales, Barney

219

Adsorption characteristics of alkanes onto carbon nanotube bundles: Grand Canonical Monte Carlo simulation  

E-print Network

Adsorption characteristics of alkanes onto carbon nanotube bundles: Grand Canonical Monte Carlo The separation of alkanes is important for a range of applications such as oil refinement, filtration and gas alkane adsorption and separation. Rather than remaining isolated however, nanotubes tend to bundle

Maruyama, Shigeo

220

Vibrational Sum-Frequency Spectroscopy of Alkane/Water Interfaces: Experiment and Theoretical Simulation  

E-print Network

Vibrational Sum-Frequency Spectroscopy of Alkane/Water Interfaces: Experiment and Theoretical, 2002 The vibrational spectra of interfacial water at a series of alkane/water interfaces have been to characterize the water-water and alkane-water interactions present at these hydrophobic/aqueous interfaces

Richmond, Geraldine L.

221

A New Intermolecular Potential Model for the n-Alkane Homologous Series  

E-print Network

A New Intermolecular Potential Model for the n- Alkane Homologous Series Jeffrey R. Errington model for the n-alkane homologous series has been developed, param- eterized to the vapor models. The simplest of hydrocarbons are the n-alkanes, which are flexible linear chains of methylene

222

Using cuticular wax alkanes to estimate herbage intake in animals fed supplements  

E-print Network

Using cuticular wax alkanes to estimate herbage intake in animals fed supplements H Dove RW Mayes M Research Institute, Craigiebuckler, Aberdeen A89 20J, Scotland The odd-chain hydrocarbons (alkanes) of plant cuticular wax, in combination with orally-dosed, even-chain alkanes of adjacent chain length, can

Boyer, Edmond

223

Catalytic hydrogenation of alkenes on acidic zeolites: Mechanistic connections to monomolecular alkane dehydrogenation reactions  

E-print Network

alkane dehydrogenation reactions Rajamani Gounder, Enrique Iglesia Department of Chemical Engineering Keywords: Alkene hydrogenation Alkane dehydrogenation Brønsted acid catalysis De Donder relations Microscopic reversibility Monomolecular alkane activation Zeolite catalysis a b s t r a c t Brønsted acid

Iglesia, Enrique

224

Mechanism of alkane dehydrogenation catalyzed by acidic zeolites: Ab initio transition path sampling  

E-print Network

Mechanism of alkane dehydrogenation catalyzed by acidic zeolites: Ab initio transition path alkanes have been studied rather frequently. As these reactions yield rather small number of different elementary step. Dehydrogenation of short alkanes belongs to simple re- actions studied to learn more about C

Dellago, Christoph

225

Assimilation of chlorinated alkanes by hydrocarbon-utilizing fungi.  

PubMed Central

The fatty acid compositions of two filamentous fungi (Cunninghamella elegans and Penicillium zonatum) and a yeast (Candida lipolytica) were determined after the organisms were grown on 1-chlorohexadecane or 1-chlorooctadecane. These organisms utilized the chlorinated alkanes as sole sources of carbon and energy. Analyses of the fatty acids present after growth on the chlorinated alkanes indicated that 60 to 70% of the total fatty acids in C. elegans were chlorinated. Approximately 50% of the fatty acids in C. lipolytica were also chlorinated. P. zonatum contained 20% 1-chlorohexadecanoic acid after growth on either substrate but did not incorporate C18 chlorinated fatty acids. PMID:6501228

Murphy, G L; Perry, J J

1984-01-01

226

A nonequilibrium molecular dynamics study of the rheology of alkanes  

SciTech Connect

We examine the rheological properties of four different alkanes: n-decane, n-hexadecane, n-tetracosane, and squalane. Simulations of Couette flow are performed for a range of shear rates with 100 molecules in each case using a replicated data version of our code. Number of interaction sites ranges from 1000 to 3000. We have performed extremely long simulations required to obtain acceptable statistics at low shear rates. The alkanes show a transition from non-Newtonian to Newtonian behavior as the shear rate decreases to low values. 1 tab, 1 fig, 17 refs.

Gupta, S.A.; Cui, S.T.; Cummings, P.T.; Cochran, H.D. [Tennessee Univ., Knoxville, TN (United States). Dept. of Chemical Engineering]|[Oak Ridge National Lab., TN (United States)

1996-05-01

227

[Carbon isotopic compositions of n-alkanes and n-alkanoic acids in the smoke from combustion of rice straw].  

PubMed

In order to investigate the carbon isotopic fractionation in n-alkanes and n-alkanoic acids in smoke from rice straw combustion, six types of rice straw were burned in laboratory under flaming and smoldering conditions, and the compound specific isotopic compositions for the two classes of biomarkers in the smoke were determined. The results showed that the delta13C values of individual n-alkanes and n-alkanoic acids released from flaming burns of all the rice species ranged from -28.6 per thousand to -38.8 per thousand and from -29.6 per thousand to -41.9per thousand, respectively, and that the mean delta13C values for the two compound classes in the flaming smoke for the six types of rice straw were in the range of -32.6 per thousand to -36. 4per thousand and -34.0 per thousand to -36.2 per thousand, respectively. Moreover, the n-alkanes in the smoke from the most straws were more depleted in 13C in general than the identical substances with equal carbon number in corresponding unburned biomass. The magnitude of the isotopic discrimination (delta) was up to 4.1per thousand. Conversely, the n-alkanoic acids in the smoke tended to be more enriched in 13C than the corresponding biomarkers in the unburned straw for all of the species, and the delta was up to 6.3 per thousand. The delta13C values of the individual n-alkanes and n-alkanoic acids in the smoke from smoldering burns of the six species varied between -31.7 per thousand and -39.0 per thousand and between -31.3 per thousand and -38.8 per thousand, respectively. The average values for the two compound classes in the smoke for a species were in the range of -35.1 per thousand to -36.4 per thousand and -34.4 per thousand to -35.6 per thousand, respectively. The compound specific delta13C values of the n-alkanes in the smoke for most species were smaller than those of the same substances in the corresponding rice straw, and the greatest delta was 6.1 per thousand. However, the delta13C values of n-alkanoic acids in the smoke were greater than those in the rice straw, and the delta was up to 8.4 per thousand. The n-alkanes from the smoldering burn were more depleted in 13C than those from the flaming burn of the identical rice species, whereas the n-alkanoic acids (> or = C19) more enriched in 13C. These results suggest that there is significant difference in the carbon isotopic composition of individual n-alkanes or n-alkanoic acids in the smoke derived from rice straw combustion and the unburned biomass, and that converse carbon isotopic fractionation occurs in the two compound classes in the smoke relative to those in the rice straw. PMID:23379139

Liu, Gang; Sun, Li-Na; Li, Jiu-Hai; Xu, Hui

2012-12-01

228

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

NASA Astrophysics Data System (ADS)

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.

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

2014-08-01

229

Energy conversion & storage program. 1994 annual report  

SciTech Connect

The Energy Conversion and Storage Program investigates state-of-the-art electrochemistry, chemistry, and materials science technologies for: (1) development of high-performance rechargeable batteries and fuel cells; (2) development of high-efficiency thermochemical processes for energy conversion; (3) characterization of complex chemical processes and chemical species; (4) study and application of novel materials for energy conversion and transmission. Research projects focus on transport process principles, chemical kinetics, thermodynamics, separation processes, organic and physical chemistry, novel materials, and advanced methods of analysis.

Cairns, E.J.

1995-04-01

230

Energy Conversion & Storage Program, 1993 annual report  

SciTech Connect

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.

Cairns, E.J.

1994-06-01

231

Chemistry 675 Advanced Organic Chemistry  

E-print Network

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 deals with the structure and reactivity of organic molecules and provides the foundation

Doyle, Robert

232

Variation in n-alkane dD values from terrestrial plants at high latitude: Implications for paleoclimate reconstruction  

E-print Network

Variation in n-alkane dD values from terrestrial plants at high latitude: Implications of the hydrogen iso- tope composition of n-alkanes (dDn-alkane) from a global dataset of individual plants growing in these regions. We pre- viously noticed smaller apparent hydrogen isotope fractionations between n-alkanes

233

Pathway of n-alkane oxidation in Cladosporium resinae.  

PubMed

Pathways of initial oxidation of n-alkanes were examined in two strains of Cladosporium resinae. Cells grow on dodecane and hexadecane and their primary alcohol and monoic acid derivatives. The homologous aldehydes do not support growth but are oxidized by intact cells and by cell-free preparations. Hexane and its derivatives support little or no growth, but cell extracts oxidize hexane, hexanol, and hexanal. Alkane oxidation by extracts is stimulated by reduced nicotinamide adenine dinucleotide (phosphate). Alcohol and aldehyde oxidation are stimulated by nicotinamide adenine dinucleotide (phosphate), and reduced coenzymes accumulate in the presence of cyanide or azide. Extracts supplied with (14)C-hexadecane convert it to the alcohol, aldehyde, and acid. Therefore, the major pathway for initial oxidation of n-alkanes is via the primary alcohol, aldehyde, and monoic acid, and the system can act on short-, intermediate-, and long-chain substrates. Thus, filamentous fungi appear to oxidize n-alkanes by pathways similar to those used by bacteria and yeasts. PMID:4146874

Walker, J D; Cooney, J J

1973-08-01

234

Cyano- and polycyanometallo-porphyrins as catalysts for alkane oxidation  

DOEpatents

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.

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

1993-05-18

235

Cyano- and polycyanometallo-porphyrins as catalysts for alkane oxidation  

DOEpatents

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.

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

1995-01-17

236

Diverse alkane hydroxylase genes in microorganisms and environments  

PubMed Central

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

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

237

Transport properties of alkanes through ceramic thin zeolite MFI membranes  

Microsoft Academic Search

Polycrystalline randomly oriented defect free zeolite layers on porous ?-Al2O3 supports are prepared with a thickness of less than 5 ?m by in situ crystallisation of silicalite-1. The flux of alkanes is a function of the sorption and intracrystalline diffusion. In mixtures of strongly and weakly adsorbing gases and a high loadings of the strongly adsorbing molecule in the zeolite

Z. A. E. P. Vroon; K. Keizer; M. J. Gilde; H. Verweij; A. J. Burggraaf

1996-01-01

238

Roaming radical pathways for the decomposition of alkanes.  

SciTech Connect

CASPT2 calculations predict the existence of roaming radical pathways for the decomposition of propane, n-butane, isobutane and neopentane. The roaming radical paths lead to the formation of an alkane and an alkene instead of the expected radical products. The predicted barriers for the roaming radical paths lie {approx}1 kcal/mol below the corresponding radical asymptotes.

Harding, L. B.; Klippenstein, S. J. (Chemical Sciences and Engineering Division)

2010-01-01

239

Cyano- and polycyanometallo-porphyrins as catalysts for alkane oxidation  

DOEpatents

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.

Ellis, Jr., Paul E. (Downingtown, PA); Lyons, James E. (Wallingford, PA)

1995-01-01

240

Cyano- and polycyanometallo-porphyrins as catalysts for alkane oxidation  

DOEpatents

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.

Ellis, Jr., Paul E. (Downingtown, PA); Lyons, James E. (Wallingford, PA)

1993-01-01

241

Cyano- and polycyanometalloporphyrins as catalysts for alkane oxidation  

DOEpatents

Alkanes are oxidized by contact with oxygen-containing gas in the presence as catalyst of a metalloporphyrin in which hydrogen atoms in the porphyrin ring have been substituted with one or more cyano groups. Hydrogen atoms in the porphyrin ring may also be substituted with halogen atoms.

Ellis, Jr., Paul E. (Downingtown, PA); Lyons, James E. (Wallingford, PA)

1992-01-01

242

Molecular modeling of the physical properties of the alkanes  

Microsoft Academic Search

Eight physical properties (boiling points, molar volumes, molar refractions, heats of vaporization, surface tensions, melting points, critical temperatures, and critical pressures) of 74 normal and branched alkanes were examined by molecular modeling techniques. Structural parameters employed include Wiener indices, connectivity indices, ad hoc descriptors, information indices, and molecular volumes and surface areas. Most of the properties were well modeled (r²

Diane E. Needham; I Chien. Wei; Paul G. Seybold

1988-01-01

243

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

PubMed Central

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

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

2002-01-01

244

Hydrocarbons. Independent Learning Project for Advanced Chemistry (ILPAC). Unit O1.  

ERIC Educational Resources Information Center

This unit on hydrocarbons is one of 10 first year units produced by the Independent Learning Project for Advanced Chemistry (ILPAC). The unit is divided into sections dealing with alkanes, alkenes, alkynes, arenes, and several aspects of the petroleum industry. Two experiments, exercises (with answers), and pre- and post-tests are included.…

Inner London Education Authority (England).

245

Green Chemistry  

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, 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.

2002-01-01

246

Metric Conversion  

Atmospheric Science Data Center

... 1,000,000 1,000,000 micrometers nano- 1,000,000,000 1,000,000,000 nanometers ... conversions, see the National Institute of Standards and Technology (NIST) Special Publications: NIST Guide to SI Units: ...

2013-03-12

247

Digital biology and chemistry.  

PubMed

This account examines developments in "digital" biology and chemistry within the context of microfluidics, from a personal perspective. Using microfluidics as a frame of reference, we identify two areas of research within digital biology and chemistry that are of special interest: (i) the study of systems that switch between discrete states in response to changes in chemical concentration of signals, and (ii) the study of single biological entities such as molecules or cells. In particular, microfluidics accelerates analysis of switching systems (i.e., those that exhibit a sharp change in output over a narrow range of input) by enabling monitoring of multiple reactions in parallel over a range of concentrations of signals. Conversely, such switching systems can be used to create new kinds of microfluidic detection systems that provide "analog-to-digital" signal conversion and logic. Microfluidic compartmentalization technologies for studying and isolating single entities can be used to reconstruct and understand cellular processes, study interactions between single biological entities, and examine the intrinsic heterogeneity of populations of molecules, cells, or organisms. Furthermore, compartmentalization of single cells or molecules in "digital" microfluidic experiments can induce switching in a range of reaction systems to enable sensitive detection of cells or biomolecules, such as with digital ELISA or digital PCR. This "digitizing" offers advantages in terms of robustness, assay design, and simplicity because quantitative information can be obtained with qualitative measurements. While digital formats have been shown to improve the robustness of existing chemistries, we anticipate that in the future they will enable new chemistries to be used for quantitative measurements, and that digital biology and chemistry will continue to provide further opportunities for measuring biomolecules, understanding natural systems more deeply, and advancing molecular and cellular analysis. Microfluidics will impact digital biology and chemistry and will also benefit from them if it becomes massively distributed. PMID:24889331

Witters, Daan; Sun, Bing; Begolo, Stefano; Rodriguez-Manzano, Jesus; Robles, Whitney; Ismagilov, Rustem F

2014-09-01

248

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 ...

249

Chemistry Notes.  

ERIC Educational Resources Information Center

Presents background information, laboratory procedures, classroom materials/activities, and chemistry experiments. Topics include sublimation, electronegativity, electrolysis, experimental aspects of strontianite, halide test, evaluation of present and future computer programs in chemistry, formula building, care of glass/saturated calomel…

School Science Review, 1983

1983-01-01

250

Colour Chemistry  

ERIC Educational Resources Information Center

Discusses the course offerings in pure color chemistry at two universities and the three main aspects of study: dyestuff chemistry, color measurement, and color application. Indicates that there exists a constant challenge to ingenuity in the subject discipline. (CC)

Griffiths, J.; Rattee, I. D.

1973-01-01

251

Chemistry Notes.  

ERIC Educational Resources Information Center

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…

School Science Review, 1982

1982-01-01

252

Introduction to Solar Photon Conversion  

SciTech Connect

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.

Nozik, Arthur J; Miller, John

2010-01-01

253

Forensic Chemistry  

NASA Astrophysics Data System (ADS)

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.

Bell, Suzanne

2009-07-01

254

Robert M. Corn Department of Chemistry  

E-print Network

, WI 53706 The chemistry of solid-liquid inter- faces affects a wide variety of impor- tant scientific and technological areas such as electroanalytical chemistry, heterogeneous catalysis, solar energy conversion (depicted in Figure 1) is the 0003-2700191/0363-285A/$02.50/0 @ 1991 American Chemical Society media, SHG

255

To Form a Favorable Idea of Chemistry  

ERIC Educational Resources Information Center

"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…

Heikkinen, Henry W.

2010-01-01

256

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."

257

The vibrational spectrum of water in liquid alkanes.  

PubMed Central

The water wire hypothesis of hydrogen-ion transport in lipid bilayers has prompted a search for water aggregates in bulk hydrocarbons. The asymmetric stretching vibration of the water dissolved in n-decane and in a number of other alkanes and alkenes has been observed. The water band in the alkanes is very wide and fits to the results of a J-diffusion calculation for the water rotation. This implies that the water is freely rotating between collisions with the solvent and certainly not hydrogen bonded to anything. The existence of water aggregates is thus most unlikely. In contrast, water in an alkene is hydrogen bonded to the solvent molecules (although not to other water molecules) and shows an entirely different spectrum. PMID:4016205

Conrad, M P; Strauss, H L

1985-01-01

258

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

ERIC Educational Resources Information Center

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…

Breslow, Ronald

259

Commensurate `freezing' of alkanes in the channels of a zeolite  

Microsoft Academic Search

FLUIDS confined in narrow pores can have properties that are distinctly different from those of bulk fluids1,2. Most studies of fluids in pores have focused on simple fluids which can be modelled as near-spherical molecules. But molecular shape can also exert an influence on the fluid's behaviour, particularly for large and\\/or complex molecules. The adsorption isotherms of alkanes in the

Berend Smit; Theo L. M. Maesen

1995-01-01

260

Alkane Biosynthesis Genes in Cyanobacteria and Their Transcriptional Organization  

PubMed Central

In cyanobacteria, alkanes are synthesized from a fatty acyl-ACP by two enzymes, acyl–acyl 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

Klähn, Stephan; Baumgartner, Desirée; Pfreundt, Ulrike; Voigt, Karsten; Schön, Verena; Steglich, Claudia; Hess, Wolfgang R.

2014-01-01

261

Alkane Biosynthesis Genes in Cyanobacteria and Their Transcriptional Organization.  

PubMed

In cyanobacteria, alkanes are synthesized from a fatty acyl-ACP by two enzymes, acyl-acyl 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

Klähn, Stephan; Baumgartner, Desirée; Pfreundt, Ulrike; Voigt, Karsten; Schön, Verena; Steglich, Claudia; Hess, Wolfgang R

2014-01-01

262

Syngas in millisecond reactors: higher alkanes and fast lightoff  

Microsoft Academic Search

Steady-state and transient catalytic partial oxidation of hydrocarbons (methane, butane, cyclohexane, n-hexane, isooctane, decane) has been carried out on rhodium-coated alumina monoliths in an effort to determine whether higher alkanes can be successfully converted to H2 and CO in short contact time reactors. This process is also necessary to determine the feasibility of on-board hydrogen generation for fuel cell and

L. D. Schmidt; E. J. Klein; C. A. Leclerc; J. J. Krummenacher; K. N. West

2003-01-01

263

Removal of alkanes from drinking water using membrane technologies  

SciTech Connect

Increasingly, the public is concerned about the quality of its drinking water. The chlorinated alkanes are saturated, aliphatic, synthetic organic compounds (SOC`s). When hydrocarbon feedstocks are chlorinated, a wide variety of chlorocarbons and chlorohydrocarbons are produced that are used as industrial solvents, degreasers and intermediaries. Because compounds such as Carbon Tetrachloride and 1,2-Dichloroethane are widely used, they often find their way into drinking water, particularly groundwaters. Surface waters are somewhat less affected bemuse of the high volatility of many chlorinated alkanes. The Drinking Water Research Division is responsible for evaluating various membrane technologies that may be feasible for meeting Maximum Contaminant Levels. Several membrane processes are under investigation to determine their effectiveness in removing SOC`s from drinking water. One study addressed the removal of a variety of alkanes from spiked groundwater by six reverse osmosis membranes: a cellulose acetate, a polyamide (hollow fiber), and four different types of thin-film composite membranes. Progressive chlorination of methanes, ethanes and propanes produces compounds that exhibit differing physicochemical properties. The differences in compound properties have an effect on the removal of these compounds by reverse osmosis membranes. For example only 25% of the methylene chloride (Dichloromethane) was removed by one thin-film composite versus 90% removal of the carbon tetrachloride. In addition, the various membranes are made of different polymeric materials and showed a wide range of removals. Generally, the thin-film composite membranes out performed the other membranes and the more highly chlorinated the compound the better the removal. Pervaporation is yet another membrane process that may prove effective in removal of alkanes and future studies will address its usefulness as a drinking water.

Fronk, C.A. [Environmental Protection Agency, Cincinnati, OH (United States)

1995-10-01

264

Binary Mixtures of n-Alkanes for Tunable Thermohydraulic Microactuators  

Microsoft Academic Search

The two objectives of this paper are related to the use of n-alkanes in actuators. The first objective is to study the thermomechanics of binary mixtures of dotriacontane and hexatriacontane to see if a quasi-stable thermal expansion can be obtained, and the second one is to find the correspondence between dilatometry [pressure, volume, and temperature (pVT) measurement] and differential scanning

Marcus Lehto; Jan-Åke Schweitz; G. Thomell

2007-01-01

265

Ultrastructure of Candida yeasts grown on n -alkanes  

Microsoft Academic Search

Catalase activities of the cells growing onn-alkanes of various strains ofCandida yeasts wer markedly higher than those of the cells growing on glucose, ethanol or acetate. In connection with this, electron-microscopical studies revealed abundant appearance of specific microbodies having homogeneous matrix surrounded by single unit membrane in the hydrocarbon-growing cells. Localization of catalase activity in the microbodies, in addition to

Masako Osumi; Naoto Miwa; Yutaka Teranishi; Atsuo Tanaka; Saburo Fukui

1974-01-01

266

Hydroxylation of alkanes using sodium hypochlorite catalyzed by iron porphyrins  

SciTech Connect

This communication presents data about the oxidation of alkanes to alcohols with hypochlorite in the presence of Fe(III) phenylporphyrin derivatives in the system water-benzene. We used as catalysts the following compounds: tetraphenylporphyrin iron chloride, tetramesitylporphyrin iron chloride, tetra(2-fluorophenyl)porphyrin from chloride, and tetra (2-ntrophenyl)porphyrin iron chloride. The reaction products were analyzed by gas-liquid chromatography. The efficiency of the reaction was determined by the structure of the porphyrin used.

Sorokin, A.B.; Khenkin, A.M.

1988-10-01

267

Long chain alkanes in silk extracts of maize genotypes with varying resistance to Fusarium graminearum.  

PubMed

The alkane content of the silks of nine maize genotypes was analyzed to investigate the role of silk wax in resistance to Fusarium graminearum. Silk samples were collected 2, 4, 6, and 8 days after silk emergence and divided into three sections: exposed silk, silk channel silk, and silk that is under the husk and overlying the kernels. Four major unbranched alkanes (C(25), C(27), C(29), and C(31)) and three isoalkanes (C(27i), C(29i), and C(31i)) were identified. Total alkane contents were highest in the exposed silk followed by the silk channel silk, with the lowest in the youngest silk closest to the kernels. In the silk channel and overlying kernel silks, the moderately resistant inbred CO272 consistently had the highest alkane content. None of the other inbreds with improved resistance had as high a level of alkanes as CO272, indicating that alkane content is not a major mechanism of resistance. PMID:14582963

Miller, S Shea; Reid, Lana M; Butler, Gail; Winter, Susan P; McGoldrick, Nadia J

2003-11-01

268

Biochemical studies on the metabolic activation of halogenated alkanes.  

PubMed Central

This paper reviews recent investigations by Slater and colleagues into the metabolic activation of halogenated alkanes in general and carbon tetrachloride in particular. It is becoming increasingly accepted that free radical intermediates are involved in the toxicity of many such compounds through mechanisms including lipid peroxidation, covalent binding, and cofactor depletion. Here we describe the experimental approaches that are used to establish that halogenated alkanes are metabolized in animal tissues to reactive free radicals. Electron spin resonance spectroscopy is used to identify free-radical products, often using spin-trapping compounds. The generation of specific free radicals by radiolytic methods is useful in the determination of the precise reactivity of radical intermediates postulated to be injurious to the cell. The enzymic mechanism of the production of such free radicals and their subsequent reactions with biological molecules is studied with specific metabolic inhibitors and free-radical scavengers. These combined techniques provide considerable insight into the process of metabolic activation of halogenated compounds. It is readily apparent, for instance, that the local oxygen concentration at the site of activation is of crucial importance to the subsequent reactions; the formation of peroxy radical derivatives from the primary free-radical product is shown to be of great significance in relation to carbon tetrachloride and may be of general importance. However, while these studies have provided much information on the biochemical mechanisms of halogenated alkane toxicity, it is clear that many problems remain to be solved. PMID:3007102

Cheeseman, K H; Albano, E F; Tomasi, A; Slater, T F

1985-01-01

269

Cold-tolerant alkane-degrading Rhodococcus species from Antarctica  

SciTech Connect

Bioremediation is a possible mechanism for clean-up of hydrocarbon-contaminated soils in the Antarctic. Microbes indigenous to the Antarctic are required that degrade the hydrocarbon contaminants found in the soil, and that are able to survive and maintain activity under in situ conditions. Alkane-degrading bacteria previously isolated from oil-contaminated soil from around Scott Base, Antarctica, grew on a number of n-alkanes from hexane (C6) through to eicosane (C20) and the branched alkane pristane. Mineralization of {sup 14}C-dodecane was demonstrated with four strains. Representative isolates were identified as Rhodococcus species using 16S rDNA sequence analysis. Rhodococcus spp. strains 5/14 and 7/1 grew at -2 C but numbers of viable cells declined when incubated t 37 C. Both strains appear to have the major cold-shock gene cspA. Partial nucleotide sequence analyses of the PCR-amplified cspA open reading frame from Rhodococcus spp. strains 5/14 and 7/1 were approximately 60% identical to cspA from Escherichia coli.

Bej, A.K.; Saul, D.; Aislabie, J.

2000-07-01

270

Dielectric constant of liquid alkanes and hydrocarbon mixtures.  

PubMed

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. PMID:11538383

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

1992-01-01

271

Dielectric constant of liquid alkanes and hydrocarbon mixtures  

NASA Technical Reports Server (NTRS)

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.

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

1992-01-01

272

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

DOEpatents

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.

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

1988-02-16

273

Selective catalytic transfer dehydrogenation of alkanes and heterocycles by an iridium pincer complex.  

PubMed

Catalytic alkane dehydrogenation is a reaction with tremendous potential for application. We describe a highly active PSCOP-pincer iridium catalyst for transfer dehydrogenation of cyclic and linear alkanes. The dehydrogenation of linear alkanes occurs under relatively mild conditions with high regioselectivity for ?-olefin formation. In addition, the catalyst system is very effective in the dehydrogenation of heterocycles to form heteroarenes and olefinic products. PMID:24382741

Yao, Wubing; Zhang, Yuxuan; Jia, Xiangqing; Huang, Zheng

2014-01-27

274

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

DOEpatents

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.

Crabtree, Robert H. (Bethany, CT); Brown, Stephen H. (East Haven, CT)

1988-01-01

275

Fundamental Flame Velocities of Pure Hydrocarbons I : Alkanes, Alkenes, Alkynes Benzene, and Cyclohexane  

NASA Technical Reports Server (NTRS)

The flame velocities of 37 pure hydrocarbons including normal and branched alkanes, alkenes, and alkynes; as well as benzene and cyclohexane, together with the experimental technique employed are presented. The normal alkanes have about the same flame velocity from ethane through heptane with methane being about 16 percent lower. Unsaturation increases the flame velocity in the order of alkanes, alkenes, and alkynes. Branching reduces the flame velocity.

Gerstein, Melvin; Levine, Oscar; Wong, Edgar L

1950-01-01

276

Desorption energies of linear and cyclic alkanes on surfaces: anomalous scaling with length  

E-print Network

Desorption energies of linear and cyclic alkanes on surfaces: anomalous scaling with length Ryan Z Abstract The desorption energies, DEz des, of linear and cyclic alkanes on the Cu(1 1 1) and Pt(1 1 1 surfaces. For sets of short linear and cyclic alkanes (n-CN H2Nþ2 and c-CN H2N , N ¼ 3­12) desorbing from

Gellman, Andrew J.

277

Identification and structural characterisation of novel trehalose dinocardiomycolates from n-alkane-grown Rhodococcus opacus 1CP.  

PubMed

Rhodococcus opacus 1CP, a potent degrader of (chloro-) aromatic compounds was found to utilise C10-C16 n-alkanes as sole carbon sources. Highest conversion rates were observed with n-tetradecane and n-hexadecane, whereas the utilisation of n-dodecane and n-decane was considerably slower. Thin-layer chromatography of organic extracts of n-alkane-grown 1CP cultures indicated the growth-associated formation of a glycolipid which was characterised as a trehalose dimycolate by 1H-NMR spectroscopy and mass spectrometry. Total chain lengths between 48 and 54 carbons classify the fatty acid residues as nocardiomycolic acids. The presence of two double bonds in each mycolic acid is another feature that distinguishes the corresponding trehalose dinocardiomycolates from trehalose dicorynomycolates reported for Rhodococcus erythropolis DSM43215 and Rhodococcus ruber IEGM231. R. opacus 1CP was not found, even under nitrogen limitation, to produce anionic trehalose tetraesters which have previously been reported for R. erythropolis DSM43215. PMID:16133336

Niescher, Susanne; Wray, Victor; Lang, Siegmund; Kaschabek, Stefan R; Schlömann, Michael

2006-05-01

278

Compound-specific hydrogen isotope composition of n-alkanes in combustion residuals of fossil fuels  

NASA Astrophysics Data System (ADS)

The hydrogen isotope compositions (?D) of n-alkanes present in the combustion residuals of fossil fuels (coal, gasoline, and diesel) were measured using GC-IRMS to distinguish between coal soot and vehicle exhaust. The n-alkane ?D values of industrial and domestic coal soot ranged from -95.3‰ to -219.6‰ and -128.1‰ to -188.6‰, respectively, exhibiting similar tendencies. The ?D values of the C15-C18n-alkanes in both types of coal soot were nearly consistent, and the ?D values of the C19-C24n-alkanes exhibited a zigzag profile. The ?D values of C16-C22n-alkanes in gasoline exhaust exhibited a saw-tooth distribution, decreased with the carbon number, and were more positive than the ?D values of C16-C22n-alkanes in diesel exhaust, which increased with the carbon number. However, the ?D values of the C23-C29n-alkanes in gasoline and diesel vehicle exhaust were mostly consistent. The weighted average ?D values of the C16-C19n-alkanes in industrial and domestic coal soot were similar to the average ?D values in gasoline and diesel vehicle exhausts; however, the average ?D values of the C21-C29n-alkanes in vehicle exhausts were richer in D than those in coal soot.

Bai, Huiling; Peng, Lin; Li, Zhongping; Liu, Xiaofeng; Song, Chongfang; Mu, Ling

2014-11-01

279

Catagenesis and composition of petroleum: Origin of n -alkanes and isoalkanes in petroleum crudes  

NASA Astrophysics Data System (ADS)

Distribution of n-alkanes and isoalkanes in ca. 50 petroleum crudes have been examined by the gas chromatography. Molar distributions of n-alkanes with respect to their c atom numbers in the majority of crudes follow the exponential law, which signifies a random, chemical nature of n-alkane-generating processes occurring in the catagenesis stage of petroleum maturation. Similar distributions of n-alkanes were found in the products of mild thermolysis of heavy n-alkanes. Isoalkanes represent a major, 10-25%, petroleum component. The principal types of isoalkanes in crudes are monomethyl-branched, with the branches randomly positioned in the chains, and dimethyl-branched with one of the methyl groups predominantly in the second position in the chains. Thermolysis studies of individual n-alkanes, alkanoic acids, and esters in the presence of various minerals provided an explanation of the n-alkane and isoalkane distributions. Selected heavy n-alkanes are initially formed in decarboxylation reactions of heavy n-alkanoic acids and esters. Extensive thermocracking produces mixtures of lighter n-alkane and ?-olefins. The olefins, in the presence of acidic clays, are converted in cationic reactions into mixtures of predominantly mono- and dimethyl-branched isoalkanes.

Kissin, Y. V.

1987-09-01

280

Confinement-Induced Ordering of Alkanes between an Elastomer and a Solid Surface  

NASA Astrophysics Data System (ADS)

We have studied the molecular structure of liquid alkanes confined between a flexible elastomeric poly(dimethyl siloxane) lens and a rigid sapphire substrate using surface-sensitive infrared-visible sum frequency generation spectroscopy. The reduction in the gauche defects suggests ordering of liquid alkanes under confinement. The cooling of confined liquid below the freezing temperature leads to crystallization with alkane molecules lying on the substrate with the symmetry axis parallel to the surface normal. This structure is very different from the bulk alkane crystals next to sapphire or air interfaces.

Nanjundiah, Kumar; Dhinojwala, Ali

2005-10-01

281

Selective chemical conversion using sheet silicate intercalates low-temperature addition of water to 1-alkanes  

Microsoft Academic Search

When 1-hexene, 1-heptene, or 1-octane were refluxed in hexane over copper-exchanged hydrated montmorillonite, about equal amounts of the diastereoisomers of bis(2-hexyl), bis(2-heptyl), and bis(2-octyl) ether were produced, respectively, for which no other practical preparation method is known. Experimental evidence indicated that water of hydration of the interlamellar cation rather than structural water associated with the silicate structure is consumed in

J. M. Adams; J. A. Ballantine; J. M. Thomas; S. H. Graham; R. J. Laub; J. H. Purnell; P. I. Reid; W. Y. M. Shaman

1979-01-01

282

Electron impact mass spectrometry of alkanes in supersonic molecular beams.  

PubMed

The electron impact mass spectrometry of straight chain alkanes C8H18-C40H82, squalane, methylstearate, 1-chlorohexadecane, 1-bromohexadecane, and dioctylphthalate was studied by sampling them with supersonic molecular beams. A fly-through Brink-type electron impact ion source was used, utilizing a vacuum background ion filtration technique based on differences between the kinetic energy of the supersonic beam species and that of thermal molecules. The 70-eV electron impact mass spectra of all the alkanes were characterized by a pronounced or dominant molecular weight peak together with all the fragment ions normally exhibited by the standard thermal 70-eV EI mass spectra. In contrast, the NIST library of most of these molecules did not show any molecular weight peak. By eliminating tile intramolecular thermal vibrational energy we gained control over the degree of molecular ion fragmentation by the electron energy. At an electron energy of 18 eV the molecular ion dissociation was further reduced considerably, with only a small absolute reduction in the peak height by less than a factor of 2. The effect of vibrational cooling increased with the molecular size and number of atoms. Pronounced differences were observed between the mass spectra of the straight chain triacontane and its branched isomer squalane. Similar mass spectra of octacosane (C28H58) achieved with 70-eV EI in a supersonic molecular beam were obtained with a magnetic sector mass spectrometer by using an electron energy of 14 eV and an ion source temperature of 150 °C. However, this ion source temperature precluded the gas chromatography-mass spectrometry (GC-MS) of octacosane. The GC-MS of alkanes was studied with an ion trap gas chromatograph-mass spectrometer at an ion source temperature of 230 °C. Thermal peak tailing was observed for C20H42 and heavier alkanes, whereas for C28H58 and heavier alkanes the severe peak tailing made quantitative GC-MS impractical. In contrast, no peak tailing existed even with C40H82 for GC-MS in supersonic molecular beams. The minimum detected amount of eicosane (C20, H42) was shown to be 60 fg. This was demonstrated by using single ion monitoring with the quadrupole mass analyzer tuned to the molecular weight peak of 282 u. The coupling of electron impact mass spectrometry in supersonic molecular beams with hyperthermal surface ionization and a fast GC-MS inlet is briefly discussed. PMID:24222074

Dagan, S; Amirav, A

1995-02-01

283

Structure-reactivity relationships in reactions of alkane radical cations. Study of the proton transfer from alkane radical cations to alkane molecules in ?-irradiated disordered CCl 3F/alkane systems by ESR spectroscopy at cryogenic temperatures  

NASA Astrophysics Data System (ADS)

A summary is presented of ESR results obtained in ?-irradiated disordered CCl 3F/alkane systems at cryogenic temperatures, with respect to proton-donor site selectivity in the proton transfer from alkane radical cations to alkane molecules. The nature of the alkyl radicals formed by proton transfer is indicative for the site of proton donation and is derived unambiguously from ESR results by comparison with powder spectra of authentic isomeric alkyl radicals, obtained by ?-irradiation of various chloro and bromoalkanes in perdeuterated cis-decalin. The experiments can be divided into two main classes. (i) Experiments on n-alkane radical cations in the extended all- trans conformation, i.e. ESR results on the system CCl 3F/heptane. The ESR spectrum of ?-irradiated CCl 3F/heptane consists of a triplet due to heptane radical cations in the extended all- trans conformation. In this conformation, the unpaired electron is delocalized over the carbon-carbon ?-bonds as well as the two chain-end carbon-hydrogen bonds that are in the plane of the C?C skeleton. Superimposed on the ESR triplet is a low-intensity spectrum due to heptyl radicals, which increases drastically with increasing heptane concentration. The formation of these heptyl radicals can be attributed unambiguously to proton transfer from heptane radical cations to heptane molecules, taking place in small heptane clusters to which positive-hole transfer still occurs efficiently. At the onset of proton transfer with increasing heptane concentration only primary heptyl radicals are present, clearly showing that the proton transfer takes place selectively from a chain-end position, in accordance with the electronic structure of the reacting radical cations. At higher heptane concentration secondary heptyl radicals also appear as a result of intermolecular radical-site transfer, i.e. the nature of the heptyl radicals becomes governed by their thermodynamic stability. (ii) Experiments on n-alkane radical cations in the gauche-at-C 2 conformation, i.e. ESR results on the system CCl 3F/octane. The ESR spectrum of ?-irradiated CCl 3F/octane indicates that octane radical cations are largely in the gauche-at-C 2 conformation in this matrix, with large unpaired-electron (and positive-hole) density on one planar chain-end C?H bond and one planar penultimate C?H bond at the other side of the radical cation. Careful investigation of ESR spectra with increasing octane concentration clearly reveals that in this case secondary octyl radicals are present from the very onset of proton transfer, in accordance with the electronic structure of the reacting radical cations. The results clearly point to proton-donor site selectivity in the proton transfer from alkane radical cations to alkane molecules and to a strict dependence of the site of proton donation on the electronic structure and conformation of the reacting radical cations.

Ceulemans, Jan

1998-12-01

284

Cloning and expression of three ladA-type alkane monooxygenase genes from an extremely thermophilic alkane-degrading bacterium Geobacillus thermoleovorans B23.  

PubMed

An extremely thermophilic bacterium, Geobacillus thermoleovorans B23, is capable of degrading a broad range of alkanes (with carbon chain lengths ranging between C11 and C32) at 70 °C. Whole-genome sequence analysis revealed that unlike most alkane-degrading bacteria, strain B23 does not possess an alkB-type alkane monooxygenase gene. Instead, it possesses a cluster of three ladA-type genes, ladA?B23, ladA?B23, and ladB B23, on its chromosome, whose protein products share significant amino acid sequence identities, 49.8, 34.4, and 22.7 %, respectively, with that of ladA alkane monooxygenase gene found on a plasmid of Geobacillus thermodetrificans NG 80-2. Each of the three genes, ladA?B23, ladA?B23, and ladB B23, was heterologously expressed individually in an alkB1 deletion mutant strain, Pseudomonas fluorescens KOB2?1. It was found that all three genes were functional in P. fluorescens KOB2?1, and partially restored alkane degradation activity. In this study, we suggest that G. thermoleovorans B23 utilizes multiple LadA-type alkane monooxygenases for the degradation of a broad range of alkanes. PMID:24682607

Boonmak, Chanita; Takahashi, Yasunori; Morikawa, Masaaki

2014-05-01

285

Analytical Chemistry  

NSDL National Science Digital Library

This document contains a list of detailed lecture notes covering a wide range of topics including equilibrium, titrations, sample preparation, acids and bases, buffers, spectrophotometry, potentiometry and chromatography. This site is part of a collection of notes from a general chemistry course taught at the State University of West Georgia. This document gives supplementary material that could be useful to intermediate chemistry majors in an analytical chemistry course or new faculty developing a course.

Henderson, David E.

286

Energy Conversions  

NSDL National Science Digital Library

Students evaluate various everyday energy conversion devices and draw block flow diagrams to show the forms and states of energy into and out of the device. They also identify the forms of energy that are useful and the desired output of the device as well as the forms that are not useful for the intended use of the item. This can be used to lead into the law of conservation of energy and efficiency. The student activity is preceded by a demonstration of a more complicated system to convert chemical energy to heat energy to mechanical energy. Drawing the block energy conversion diagram for this system models the activity that the students then do themselves for other simpler systems.

2014-09-18

287

Chemistry Notes  

ERIC Educational Resources Information Center

Twelve new chemistry expermiments are described. Broad areas covered include atomic structure, solubility, gaseous diffusion, endothermic reactions, alcohols, equilibrium, atomic volumes, and some improvised apparatus. (PS)

School Science Review, 1972

1972-01-01

288

Doing Chemistry  

NSDL National Science Digital Library

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.

Brooks, David W.

2010-05-25

289

Technetium chemistry  

SciTech Connect

Technetium chemistry is a young and developing field. Despite the limited knowledge of its chemistry, technetium is the workhorse for nuclear medicine. Technetium is also a significant environmental concern because it is formed as a byproduct of nuclear weapons production and fission-power generators. Development of new technetium radio-pharmaceuticals and effective environmental control depends strongly upon knowledge of basic technetium chemistry. The authors performed research into the basic coordination and organometallic chemistry of technetium and used this knowledge to address nuclear medicine and environmental applications. This is the final report of a three-year Laboratory-Directed Research and Development (LDRD) project at the Los Alamos National Laboratory (LANL).

Burns, C.; Bryan, J.; Cotton, F.; Ott, K.; Kubas, G.; Haefner, S. [Los Alamos National Lab., NM (United States); Barrera, J. [Dartmouth Coll., Hanover, NH (United States); Hall, K. [Univ. of Washington, Seattle, WA (United States); Burrell, A. [Massey Univ., Palmerston North (New Zealand)

1996-04-01

290

Energy conversion and storage program  

NASA Astrophysics Data System (ADS)

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 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. Topics include identification of new electrochemical couples for advanced rechargeable batteries, improvements in battery and fuel-cell materials, and the establishment of engineering principles applicable to electrochemical energy storage and conversion. 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 waste streams from synfuel plants and coal gasifiers. Other research projects seek to identify and characterize the constituents of liquid fuel-system streams and to devise energy-efficient means for their separation. Materials Applications research includes the evaluation of the properties of advanced materials, as well as the development of novel preparation techniques. For example, the use of advanced techniques, such as sputtering and laser ablation, are being used to produce high-temperature superconducting films.

Cairns, E. J.

1992-03-01

291

Energy Conversion and Storage Program  

SciTech Connect

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 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. Topics include identification of new electrochemical couples for advanced rechargeable batteries, improvements in battery and fuel-cell materials, and the establishment of engineering principles applicable to electrochemical energy storage and conversion. 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 waste streams from synfuel plants and coal gasifiers. Other research projects seek to identify and characterize the constituents of liquid fuel-system streams and to devise energy-efficient means for their separation. Materials Applications research includes the evaluation of the properties of advanced materials, as well as the development of novel preparation techniques. For example, the use of advanced techniques, such as sputtering and laser ablation, are being used to produce high-temperature superconducting films.

Cairns, E.J.

1992-03-01

292

Identification and use of an alkane transporter plug-in for applications in biocatalysis and whole-cell biosensing of alkanes.  

PubMed

Effective application of whole-cell devices in synthetic biology and biocatalysis will always require consideration of the uptake of molecules of interest into the cell. Here we demonstrate that the AlkL protein from Pseudomonas putida GPo1 is an alkane import protein capable of industrially relevant rates of uptake of C7-C16 n-alkanes. Without alkL expression, native E.coli n-alkane uptake was the rate-limiting step in both the whole-cell bioconversion of C7-C16 n-alkanes and in the activation of a whole-cell alkane biosensor by C10 and C11 alkanes. By coexpression of alkL as a transporter plug-in, specific yields improved by up to 100-fold for bioxidation of >C12 alkanes to fatty alcohols and acids. The alkL protein was shown to be toxic to the host when overexpressed but when expressed from a vector capable of controlled induction, yields of alkane oxidation were improved a further 10-fold (8?g/L and 1.7?g/g of total oxidized products). Further testing of activity on n-octane with the controlled expression vector revealed the highest reported rates of 120??mol/min/g and 1?g/L/h total oxidized products. This is the first time AlkL has been shown to directly facilitate enhanced uptake of C10-C16 alkanes and represents the highest reported gain in product yields resulting from its use. PMID:25068650

Grant, Chris; Deszcz, Dawid; Wei, Yu-Chia; Martínez-Torres, Rubéns Julio; Morris, Phattaraporn; Folliard, Thomas; Sreenivasan, Rakesh; Ward, John; Dalby, Paul; Woodley, John M; Baganz, Frank

2014-01-01

293

Identification and use of an alkane transporter plug-in for applications in biocatalysis and whole-cell biosensing of alkanes  

NASA Astrophysics Data System (ADS)

Effective application of whole-cell devices in synthetic biology and biocatalysis will always require consideration of the uptake of molecules of interest into the cell. Here we demonstrate that the AlkL protein from Pseudomonas putida GPo1 is an alkane import protein capable of industrially relevant rates of uptake of C7-C16 n-alkanes. Without alkL expression, native E.coli n-alkane uptake was the rate-limiting step in both the whole-cell bioconversion of C7-C16 n-alkanes and in the activation of a whole-cell alkane biosensor by C10 and C11 alkanes. By coexpression of alkL as a transporter plug-in, specific yields improved by up to 100-fold for bioxidation of >C12 alkanes to fatty alcohols and acids. The alkL protein was shown to be toxic to the host when overexpressed but when expressed from a vector capable of controlled induction, yields of alkane oxidation were improved a further 10-fold (8 g/L and 1.7 g/g of total oxidized products). Further testing of activity on n-octane with the controlled expression vector revealed the highest reported rates of 120 ?mol/min/g and 1 g/L/h total oxidized products. This is the first time AlkL has been shown to directly facilitate enhanced uptake of C10-C16 alkanes and represents the highest reported gain in product yields resulting from its use.

Grant, Chris; Deszcz, Dawid; Wei, Yu-Chia; Martínez-Torres, Rubéns Julio; Morris, Phattaraporn; Folliard, Thomas; Sreenivasan, Rakesh; Ward, John; Dalby, Paul; Woodley, John M.; Baganz, Frank

2014-07-01

294

Conversational sensing  

NASA Astrophysics Data System (ADS)

Recent developments in sensing technologies, mobile devices and context-aware user interfaces have made it pos- sible to represent information fusion and situational awareness for Intelligence, Surveillance and Reconnaissance (ISR) activities as a conversational process among actors at or near the tactical edges of a network. Motivated by use cases in the domain of Company Intelligence Support Team (CoIST) tasks, this paper presents an approach to information collection, fusion and sense-making based on the use of natural language (NL) and controlled nat- ural language (CNL) to support richer forms of human-machine interaction. The approach uses a conversational protocol to facilitate a ow of collaborative messages from NL to CNL and back again in support of interactions such as: turning eyewitness reports from human observers into actionable information (from both soldier and civilian sources); fusing information from humans and physical sensors (with associated quality metadata); and assisting human analysts to make the best use of available sensing assets in an area of interest (governed by man- agement and security policies). CNL is used as a common formal knowledge representation for both machine and human agents to support reasoning, semantic information fusion and generation of rationale for inferences, in ways that remain transparent to human users. Examples are provided of various alternative styles for user feedback, including NL, CNL and graphical feedback. A pilot experiment with human subjects shows that a prototype conversational agent is able to gather usable CNL information from untrained human subjects.

Preece, Alun; Gwilliams, Chris; Parizas, Christos; Pizzocaro, Diego; Bakdash, Jonathan Z.; Braines, Dave

2014-05-01

295

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

NASA Astrophysics Data System (ADS)

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.

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

296

Second NASA Conference on Laser Energy Conversion  

NASA Technical Reports Server (NTRS)

The possible transmission of high power laser beams over long distances and their conversion to thrust, electricity, or other useful forms of energy is considered. Specific topics discussed include: laser induced chemistry; developments in photovoltaics, including modification of the Schottky barrier devices and generation of high voltage emf'sby laser radiation of piezoelectric ceramics; the thermo electronic laser energy converter and the laser plasmadynamics converters; harmonic conversion of infrared laser radiation in molecular gases; and photon engines.

Billman, K. W. (editor)

1976-01-01

297

Analyses of n-alkanes degrading community dynamics of a high-temperature methanogenic consortium enriched from production water of a petroleum reservoir by a combination of molecular techniques.  

PubMed

Despite the knowledge on anaerobic degradation of hydrocarbons and signature metabolites in the oil reservoirs, little is known about the functioning microbes and the related biochemical pathways involved, especially about the methanogenic communities. In the present study, a methanogenic consortium enriched from high-temperature oil reservoir production water and incubated at 55 °C with a mixture of long chain n-alkanes (C(15)-C(20)) as the sole carbon and energy sources was characterized. Biodegradation of n-alkanes was observed as methane production in the alkanes-amended methanogenic enrichment reached 141.47 ?mol above the controls after 749 days of incubation, corresponding to 17 % of the theoretical total. GC-MS analysis confirmed the presence of putative downstream metabolites probably from the anaerobic biodegradation of n-alkanes and indicating an incomplete conversion of the n-alkanes to methane. Enrichment cultures taken at different incubation times were subjected to microbial community analysis. Both 16S rRNA gene clone libraries and DGGE profiles showed that alkanes-degrading community was dynamic during incubation. The dominant bacterial species in the enrichment cultures were affiliated with Firmicutes members clustering with thermophilic syntrophic bacteria of the genera Moorella sp. and Gelria sp. Other represented within the bacterial community were members of the Leptospiraceae, Thermodesulfobiaceae, Thermotogaceae, Chloroflexi, Bacteroidetes and Candidate Division OP1. The archaeal community was predominantly represented by members of the phyla Crenarchaeota and Euryarchaeota. Corresponding sequences within the Euryarchaeota were associated with methanogens clustering with orders Methanomicrobiales, Methanosarcinales and Methanobacteriales. On the other hand, PCR amplification for detection of functional genes encoding the alkylsuccinate synthase ?-subunit (assA) was positive in the enrichment cultures. Moreover, the appearance of a new assA gene sequence identified in day 749 supported the establishment of a functioning microbial species in the enrichment. Our results indicate that n-alkanes are converted to methane slowly by a microbial community enriched from oilfield production water and fumarate addition is most likely the initial activation step of n-alkanes degradation under thermophilic methanogenic conditions. PMID:22688358

Zhou, Lei; Li, Kai-Ping; Mbadinga, Serge Maurice; Yang, Shi-Zhong; Gu, Ji-Dong; Mu, Bo-Zhong

2012-08-01

298

Fluid transport properties by equilibrium molecular dynamics. III. Evaluation of united atom interaction potential models for pure alkanes  

E-print Network

interaction potential models for pure alkanes D. K. Dysthe,a) A. H. Fuchs, and B. Rousseau Laboratoire de of the fluid.7 We therefore find it timely to evaluate the alkane models that are most frequently used and most

Dysthe, Dag Kristian

299

Chemistry Notes.  

ERIC Educational Resources Information Center

Outlines laboratory procedures, demonstrations, teaching suggestions, and content information related to chemistry. Topics include polarizing power; calorimetry and momentum; microcomputers in school chemistry; a constant-volume dispenser for liquids, floating magnets, and crystal lattices; preparation of chromium; and solvent polarity and…

School Science Review, 1981

1981-01-01

300

Unit Conversions  

NSDL National Science Digital Library

This resource is a digital tool for performing unit conversions. It provides the additional feature of displaying cancellation of terms, enabling users to gain a deeper understanding of the mathematical processes involved in converting units. Users can convert among 25 quantities, including units such as force, temperature, energy, and current. Also available are less commonly used units, such as illuminance and magnetic flux. In addition, the calculations respect the number of significant figures. It is part of Web-Based Computer Aided Instruction, a set of free resources for teachers and learners.

Taha Mzoughi

301

Cyclooctane metathesis catalyzed by silica-supported tungsten pentamethyl [(?SiO)W(Me)5]: distribution of macrocyclic alkanes.  

PubMed

Metathesis of cyclic alkanes catalyzed by the new surface complex [(?SiO)W(Me)5] affords a wide distribution of cyclic and macrocyclic alkanes. The major products with the formula C(n)H(2n) are the result of either a ring contraction or ring expansion of cyclooctane leading to lower unsubstituted cyclic alkanes (5?n?7) and to an unprecedented distribution of unsubstituted macrocyclic alkanes (12?n?40), respectively, identified by GC/MS and by NMR spectroscopies. PMID:25279445

Riache, Nassima; Callens, Emmanuel; Samantaray, Manoja K; Kharbatia, Najeh M; Atiqullah, Muhammad; Basset, Jean-Marie

2014-11-10

302

Identity and mechanisms of alkane-oxidizing metalloenzymes from deep-sea hydrothermal vents  

PubMed Central

Six aerobic alkanotrophs (organism that can metabolize alkanes as their sole carbon source) isolated from deep-sea hydrothermal vents were characterized using the radical clock substrate norcarane to determine the metalloenzyme and reaction mechanism used to oxidize alkanes. The organisms studied were Alcanivorax sp. strains EPR7 and MAR14, Marinobacter sp. strain EPR21, Nocardioides sp. strains EPR26w, EPR28w, and Parvibaculum hydrocarbonoclasticum strain EPR92. Each organism was able to grow on n-alkanes as the sole carbon source and therefore must express genes encoding an alkane-oxidizing enzyme. Results from the oxidation of the radical-clock diagnostic substrate norcarane demonstrated that five of the six organisms (EPR7, MAR14, EPR21, EPR26w, and EPR28w) used an alkane hydroxylase functionally similar to AlkB to catalyze the oxidation of medium-chain alkanes, while the sixth organism (EPR92) used an alkane-oxidizing cytochrome P450 (CYP)-like protein to catalyze the oxidation. DNA sequencing indicated that EPR7 and EPR21 possess genes encoding AlkB proteins, while sequencing results from EPR92 confirmed the presence of a gene encoding CYP-like alkane hydroxylase, consistent with the results from the norcarane experiments. PMID:23825470

Bertrand, Erin M.; Keddis, Ramaydalis; Groves, John T.; Vetriani, Costantino; Austin, Rachel Narehood

2013-01-01

303

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

SciTech Connect

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 that activate and/or functionalize alkanes in the liquid phase. Despite this new wealth of information, the radical chain oxidations of hydrocarbons by O{sub 2} developed by DuPont and others remain the dominant methods for introducing functional groups into alkanes. Nearly all the new systems (developed since 1980) for the non-radical-chain homogeneous catalytic functionalization of alkanes, including the intensely investigated metalloporphyrin systems, share a common and severe limitation. The catalysts in these systems are largely organic in nature and it is the thermodynamic oxidative instability of the organic structure that dooms such species as catalysts for practical and sustained selective alkane functionalization processes will oxidize the catalyst itself. When the catalyst is destroyed, alkane functionalization stops. It was in direct response to the problems of catalyst oxidative instability that we began to investigate the use of soluble completely inorganic and oxidatively resistant polyoxotungstate complexes as catalysts for homogeneous organic oxidations. Initial results for both thermal and photochemical catalytic organic oxidations indicate these complexes have superior stability. We report here both the thermal and photochemical catalytic functionalization of alkanes by heteropolytungstate complexes.

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

1987-04-01

304

40 CFR 721.2625 - Reaction product of alkane-diol and epichlorohydrin.  

Code of Federal Regulations, 2013 CFR

...2013-07-01 2013-07-01 false Reaction product of alkane-diol and epichlorohydrin. 721.2625 Section 721.2625...Specific Chemical Substances § 721.2625 Reaction product of alkane-diol and epichlorohydrin. (a) Chemical substance...

2013-07-01

305

40 CFR 721.2625 - Reaction product of alkane-diol and epichlorohydrin.  

Code of Federal Regulations, 2014 CFR

...2014-07-01 2014-07-01 false Reaction product of alkane-diol and epichlorohydrin. 721.2625 Section 721.2625...Specific Chemical Substances § 721.2625 Reaction product of alkane-diol and epichlorohydrin. (a) Chemical substance...

2014-07-01

306

40 CFR 721.2625 - Reaction product of alkane-diol and epichlorohydrin.  

Code of Federal Regulations, 2012 CFR

...2012-07-01 2012-07-01 false Reaction product of alkane-diol and epichlorohydrin. 721.2625 Section 721.2625...Specific Chemical Substances § 721.2625 Reaction product of alkane-diol and epichlorohydrin. (a) Chemical substance...

2012-07-01

307

40 CFR 721.2625 - Reaction product of alkane-diol and epichlorohydrin.  

Code of Federal Regulations, 2010 CFR

...2010-07-01 2010-07-01 false Reaction product of alkane-diol and epichlorohydrin. 721.2625 Section 721.2625...Specific Chemical Substances § 721.2625 Reaction product of alkane-diol and epichlorohydrin. (a) Chemical substance...

2010-07-01

308

CHEMICAL REACTIONS AND TRANSPORT OF ALKANES AND THEIR PRODUCTS IN THE TROPOSPHERE  

EPA Science Inventory

The product distributions have been calculated the more abundant alkanes contributing most of the carbon atoms in the alkane fraction of an ambient air hydrocarbon mixture reasonably representative of U.S. emissions, The effects of ambient temperatures on product yields has been ...

309

Estimation of dry matter intake by ewes at pasture, using the n-alkanes method  

E-print Network

Estimation of dry matter intake by ewes at pasture, using the n-alkanes method G Béchet, A Kerkeb alkanes as external and internal markers (RW Mayes et al, 1986). Three groups of 3 dry and non.05), and between N and VT, or T and VT groups (Palkane method shows, in spite

Paris-Sud XI, Université de

310

Towards a detailed understanding of the NEXAFS spectra of bulk polyethylene copolymers and related alkanes  

E-print Network

alkanes A. Schooll a,b , R. Fink b , E. Umbach b , G.E. Mitchell c , S.G. Urquhart d , H. Ade a interpretation has not yet emerged. Initially, the low energy peak of polyethylene (PE) and long- chain alkanes

311

40 CFR 721.2625 - Reaction product of alkane-diol and epichlorohydrin.  

Code of Federal Regulations, 2011 CFR

...2011-07-01 2011-07-01 false Reaction product of alkane-diol and epichlorohydrin. 721.2625 Section 721.2625...Specific Chemical Substances § 721.2625 Reaction product of alkane-diol and epichlorohydrin. (a) Chemical substance...

2011-07-01

312

Preliminary assessment of halogenated alkanes as vapor-phase tracers  

SciTech Connect

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.

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

1991-01-01

313

Solar energy conversion  

Microsoft Academic Search

The physical nature of solar radiation, some history of direct solar energy conversion, and descriptions of conversion methods are discussed. Several conversion methods are reviewed, including photosynthesis, solar cells, and solar thermal conversion. (SPH)

Maddox

1974-01-01

314

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

PubMed Central

Marine hydrocarbon seeps are ecosystems that are rich in methane, and, in some cases, short-chain (C2–C5) and longer alkanes. C2–C4 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 (C1–C4) 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 C1–C4 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 C3–C4 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

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

2013-01-01

315

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

PubMed

Marine hydrocarbon seeps are ecosystems that are rich in methane, and, in some cases, short-chain (C2-C5) and longer alkanes. C2-C4 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 (C1-C4) 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 ?(13)C 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 ?(13)C 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 C1-C4 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 C3-C4 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

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

2013-01-01

316

Draft Genome Sequence of Uncultivated Firmicutes (Peptococcaceae SCADC) Single Cells Sorted from Methanogenic Alkane-Degrading Cultures  

PubMed Central

The draft genome of an uncultivated bacterium affiliated with the Peptococcaceae was reconstructed by co-assembling Illumina MiSeq sequences from three single cells sorted by microfluidics from two methanogenic alkane-degrading cultures. Peptococcaceae SCADC (short-chain alkane-degrading culture) may be genetically capable of anaerobic alkane activation by fumarate addition in the absence of sulfate. PMID:25212628

Tan, BoonFei; Charchuk, Rhianna; Li, Carmen; Nesbø, Camilla; Abu Laban, Nidal

2014-01-01

317

CONFORMATION OF LIQUID N-ALKANES F. GOODSAID-ZALDUONDO AND D.M. ENGELMAN, Department ofMolecular  

E-print Network

CONFORMATION OF LIQUID N-ALKANES F. GOODSAID-ZALDUONDO AND D.M. ENGELMAN, Department of of liquid n-alkanes have been studied using neutron scattering techniques to better understand 4.6 A-' (1,2). The scattering from alkanes in the liquid state is very similar in this region (3

318

Investigation of the Mechanism of Alkane Reductive Elimination and Skeletal Isomerization in TpRh(CNneopentyl)(R)H Complexes: The  

E-print Network

Investigation of the Mechanism of Alkane Reductive Elimination and Skeletal Isomerization in TpRh(CNneopentyl)(R)H Complexes: The Role of Alkane Complexes Todd O. Northcutt, Douglas D. Wick, Andrew J. Vetter, and William D for the involvement of alkane -complexes in oxidative addition/reductive elimination reactions of Tp

Jones, William D.

319

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

Code of Federal Regulations, 2010 CFR

...hydroisomerized middle, C10-13-branched alkane fraction. 721.10178 Section 721...hydroisomerized middle, C10-13-branched alkane fraction. (a) Chemical substance...hydroisomerized middle, C10-13-branched alkane fraction (PMN P-04-319; CAS...

2010-07-01

320

Self-assembled alkane monolayers on MoSe2 and MoS, S. Cincotti*) and J P Rabeb). .  

E-print Network

Self-assembled alkane monolayers on MoSe2 and MoS, S. Cincotti*) and J P Rabeb). . MaxSez and MO&. Long-chain alkanes are known to adsorb particularly strongly to the basal plane of graphite carbon-carbon bond lengths in alkanes and graphite.' On the other hand, based on ther- modynamic

Peters, Achim

321

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

Code of Federal Regulations, 2012 CFR

...hydroisomerized middle, C10-13-branched alkane fraction. 721.10178 Section 721...hydroisomerized middle, C10-13-branched alkane fraction. (a) Chemical substance...hydroisomerized middle, C10-13-branched alkane fraction (PMN P-04-319; CAS...

2012-07-01

322

Solid state effects in the NEXAFS spectra of alkane-based van der Waals crystals: Breakdown of molecular model  

E-print Network

Solid state effects in the NEXAFS spectra of alkane-based van der Waals crystals: Breakdown der Waals interactions between alkane molecules, of covalent C­H orbitals and van der Waals forces in alkane crystals is $98.5% covalent. It is thus

323

Terahertz vibrational modes induced by heterogeneous nucleation in n-alkanes Jonathan P. Laib, Daniel V. Nickel, Daniel M. Mittleman *  

E-print Network

Terahertz vibrational modes induced by heterogeneous nucleation in n-alkanes Jonathan P. Laib linear n-alkanes. On cooling from the liquid into the rotator phase, the absorption is enhanced within thoroughly studied types of phase transition. Recently, the nucleation of linear normal-alkanes (CnH2n+2

Mittleman, Daniel

324

The Source of Helicity in Perfluorinated N-Alkanes Seung Soon Jang, Mario Blanco, and William A. Goddard III  

E-print Network

The Source of Helicity in Perfluorinated N-Alkanes Seung Soon Jang, Mario Blanco, and William A(alanine) are stabilized by inter- and intramolecular hydrogen bonds, respectively. Perfluorinated n-alkanes also exhibit bonds, one may ask what forces stabilize perfluorinated n-alkane helices. We combine ab initio

Goddard III, William A.

325

Alkanes are often used as markers to estimate intake of grazing animals. The use of faecal n-  

E-print Network

Alkanes are often used as markers to estimate intake of grazing animals. The use of faecal n- alkane concentrations (C31 and C33 as internal markers) was tested to estimate the variation be- tween.01) with the faecal alkane concentrations, standard errors being small (C31: 0.009; C33: 0.008). In both cases

Paris-Sud XI, Université de

326

5238 J. Phys. Chem. 1993,97, 5238-5245 Molecular Complexes of Small Alkanes with Co+  

E-print Network

5238 J. Phys. Chem. 1993,97, 5238-5245 Molecular Complexes of Small Alkanes with Co+ Jason K. Perry electron correlation, we studied the molecular complexes of Co+ with HZand a number of small alkanes (CH4,sometrendscanbediscerned. Oneimportant trend is that the larger the alkane, the more reactive it is to transition

Goddard III, William A.

327

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

Code of Federal Regulations, 2013 CFR

...hydroisomerized middle, C10-13-branched alkane fraction. 721.10178 Section 721...hydroisomerized middle, C10-13-branched alkane fraction. (a) Chemical substance...hydroisomerized middle, C10-13-branched alkane fraction (PMN P-04-319; CAS...

2013-07-01

328

Preliminary assessment of alkane and PAH data for sediment cores from six lakes in the Fraser River basin  

E-print Network

Preliminary assessment of alkane and PAH data for sediment cores from six lakes in the Fraser River including alkanes and polynuclear aromatic hydrocarbons (PAH). A preliminary examination of the data using detectable alkane and PAH compounds but there are differences between lakes and between sediment depths

329

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

Code of Federal Regulations, 2014 CFR

...Naphtha (Fischer-Tropsch), C4-11-alkane, branched and linear. 721.10103...Naphtha (Fischer-Tropsch), C4-11-alkane, branched and linear. (a) Chemical...naphtha (fischer-tropsch), C4-11-alkane, branched and linear (PMN...

2014-07-01

330

Kinetics and Mechanism of Oligomer Desorption from Surfaces: n-Alkanes on Graphite Andrew J. Gellman* and Kris R. Paserba  

E-print Network

Kinetics and Mechanism of Oligomer Desorption from Surfaces: n-Alkanes on Graphite Andrew J of the desorption of straight-chain alkanes [H(CH2)NH, N ) 5-60] from the surface of graphite has revealed with individual backbone bonds such that an alkane with N carbon atoms has I ) N - 1 segments. The oligomer

Gellman, Andrew J.

331

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

Code of Federal Regulations, 2013 CFR

...Naphtha (Fischer-Tropsch), C4-11-alkane, branched and linear. 721.10103...Naphtha (Fischer-Tropsch), C4-11-alkane, branched and linear. (a) Chemical...naphtha (fischer-tropsch), C4-11-alkane, branched and linear (PMN...

2013-07-01

332

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

Code of Federal Regulations, 2014 CFR

...hydroisomerized middle, C10-13-branched alkane fraction. 721.10178 Section 721...hydroisomerized middle, C10-13-branched alkane fraction. (a) Chemical substance...hydroisomerized middle, C10-13-branched alkane fraction (PMN P-04-319; CAS...

2014-07-01

333

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

Code of Federal Regulations, 2012 CFR

...Naphtha (Fischer-Tropsch), C4-11-alkane, branched and linear. 721.10103...Naphtha (Fischer-Tropsch), C4-11-alkane, branched and linear. (a) Chemical...naphtha (fischer-tropsch), C4-11-alkane, branched and linear (PMN...

2012-07-01

334

THE JOURNAL OF CHEMICAL PHYSICS 136, 204709 (2012) Chain-length dependent growth dynamics of n-alkanes on silica  

E-print Network

THE JOURNAL OF CHEMICAL PHYSICS 136, 204709 (2012) Chain-length dependent growth dynamics of n-alkanes 2012; published online 31 May 2012) We compare the growth dynamics of the three n-alkanes C36H74, C40H formed by longer n-alkanes roughen faster during growth. This behavior can be explained by a chain

Schreiber, Frank

335

Source of Image Contrast in STM Images of Functionalized Alkanes on Graphite: A Systematic Functional Group Approach  

E-print Network

Source of Image Contrast in STM Images of Functionalized Alkanes on Graphite: A Systematic of functionalized alkanes and/or alkyl alcohols have been prepared and imaged by scanning tunneling microscopy (STM identification of individual hydrogen atoms in the alkane chains, but in all cases allowing identification

Goddard III, William A.

336

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

Code of Federal Regulations, 2011 CFR

...hydroisomerized middle, C10-13-branched alkane fraction. 721.10178 Section 721...hydroisomerized middle, C10-13-branched alkane fraction. (a) Chemical substance...hydroisomerized middle, C10-13-branched alkane fraction (PMN P-04-319; CAS...

2011-07-01

337

Feasibility of reconstructing paleoatmospheric records of selected alkanes, methyl halides, and sulfur gases from Greenland ice cores  

E-print Network

Feasibility of reconstructing paleoatmospheric records of selected alkanes, methyl halides-butyl acetate as the drill fluid would have on the measurements. The gases include three light alkanes, C2H6, C3, with gas ages from 125 to 325 years before present. Alkane levels are comparable to measurements in modern

Saltzman, Eric

338

Extent of Reduction of Vanadium Oxides during Catalytic Oxidation of Alkanes Measured by in-Situ UV-Visible Spectroscopy  

E-print Network

Extent of Reduction of Vanadium Oxides during Catalytic Oxidation of Alkanes Measured by in-Situ UV to oxidation reactions using lattice oxygens as reactive intermediates. Introduction Oxidative alkane-visible spectroscopy probes the electronic structure of oxide domains commonly used in alkane ODH catalysis.6

Bell, Alexis T.

339

Polycyclic Aromatic Hydrocarbons and n-alkanes in sediments of the Upper Scheldt River Basin: contamination levels and source apportionment  

E-print Network

Polycyclic Aromatic Hydrocarbons and n-alkanes in sediments of the Upper Scheldt River Basin River at Wervik and the Espierre Canal), were analysed for n-alkanes and polycyclic aromatic hydrocarbons (PAHs). Total n-alkane and PAH concentrations in all the sampled cores ranged from 2.8 to 29 mg kg

Boyer, Edmond

340

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

Code of Federal Regulations, 2010 CFR

...Naphtha (Fischer-Tropsch), C4-11-alkane, branched and linear. 721.10103...Naphtha (Fischer-Tropsch), C4-11-alkane, branched and linear. (a) Chemical...naphtha (fischer-tropsch), C4-11-alkane, branched and linear (PMN...

2010-07-01

341

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

Code of Federal Regulations, 2011 CFR

...Naphtha (Fischer-Tropsch), C4-11-alkane, branched and linear. 721.10103...Naphtha (Fischer-Tropsch), C4-11-alkane, branched and linear. (a) Chemical...naphtha (fischer-tropsch), C4-11-alkane, branched and linear (PMN...

2011-07-01

342

Geologic seepage of methane and light alkanes in Los Angeles  

NASA Astrophysics Data System (ADS)

Natural geologic seepage of methane from underground oil and natural gas reservoirs has been suggested to be an underreported part of the global methane budget. Other light alkanes are also given off in combination with the methane seepage, making it possible that geologic seepage is also a potentially significant global source of these light alkanes. This study reports C1-C5 findings from geologic seepage made in the Los Angeles region. Microseepage, invisible escape of gases, was measured primarily at Kenneth Hahn Regional Park, while macroseepage, the visible release of gases, was measured at the La Brea Tar Pits. Samples were collected using stainless steel canisters and flux chambers and were analyzed using gas chromatography with flame ionization detectors (GC-FID). Average microseepage flux rates of 0.95 ?g m-2 h-1 for ethane and 0.51 ?g m-2 h-1 were found for propane, while average macroseepage rates for methane, ethane, and propane were 664, 19.8, and 18.1 mg m-2 h-1 respectively. Relationships between microseepage flux rate and location of underground oil and natural deposit and earthquake fault lines are presented. Additionally, the relative importance of findings in context with global budgets and local air quality is discussed.

Doezema, L. A.; Chang, K.; Baril, R.; Nwachuku, I.; Contreras, P.; Marquez, A.; Howard, D.

2013-12-01

343

Measurement of n-alkanals and hydroxyalkenals in biological samples.  

PubMed

A modified method was developed to measure nM levels of a range of n-alkanals and hydroxyalkenals in biological samples such as blood plasma and tissue homogenates and also in Folch lipid extracts of these samples. Butylated hydroxytoluene (BHT) and desferrioxamine (Desferal) were added to samples to prevent artifactual peroxidation. Aldehydes were reacted with 1,3-cyclohexanedione (CHD), cleaned up by solid-phase extraction on a Sep-Pak C18 cartridge and the fluorescent decahydroacridine derivatives resolved by reverse-phase high-performance liquid chromatography (HPLC) with gradient elution. A wider range of aldehydes was detected in lipid extracts of plasma and liver homogenate compared to whole (unextracted) samples. Human plasma contained nM levels of acetaldehyde, propanal, butanal, pentanal, hexanal, and heptanal. 4-Hydroxynonenal (0.93 nmol/g) and alkanals with two to six carbons (up to 7.36 nmol/g) were detected in rat liver. Recovery of aldehydes added to whole plasma or to lipid extracts of plasma was dependent on carbon chain length, varying from 95% for acetaldehyde to 8% for decanal. Recovery from biological samples was significantly less than that of standards taken through the Sep-Pak clean-up procedure, suggesting that aldehydes can bind to plasma protein and lipid components. PMID:8406128

Holley, A E; Walker, M K; Cheeseman, K H; Slater, T F

1993-09-01

344

Multiple sources of alkanes in Quaternary oceanic sediment of Antarctica  

USGS Publications Warehouse

Normal alkanes (n-C13n-C36), isoprenoid hydrocarbons (i-C15, i-C16, i-C18, i-C19, and i-C20) triterpanes (C27C32), and (C27C29) are present in low concentrations offshore Antarctica in near-surface, Quaternary sediment of the Wilkes Land continental margin and of the western Ross Sea. The distributions of these hydrocarbons are interpreted relative to possible sources and processes. The hydrocarbons appear to be mixtures of primary and recycled material from marine and terrigenous sources. The n-alkanes are most abundant and are characterized by two distinct populations, one of probable marine origin and the other likely from terrigenous, vascular plant sources. Because the continent of Antarctica today is devoid of higher plants, the plant-derived hydrocarbons in these offshore sediments probably came from wind-blown material and recycled Antarctic sediment that contains land-plant remains from an earlier period of time. Isoprenoid hydrocarbons are partially recycled and mainly of marine origin; the dominance of pristane over phytane suggests oxic paleoenvironmental conditions. Both modern and ancient triterpanes and steranes are present, and the distribution of these indicates a mixture of primary and recycled bacterial, algal, and possible higher-plant materials. Although the sampled sediments were deposited during the Quaternary, they apparently contain a significant component of hydrocarbons of pre-Quaternary age. ?? 1987.

Kvenvolden, K.A.; Rapp, J.B.; Golan-Bac, M.; Hostettler, F.D.

1987-01-01

345

Iron disulfide for solar energy conversion  

Microsoft Academic Search

Pyrite (Eg = 0.95 eV) is being developed as a solar energy material due to its environmental compatibility and its very high light absorption coefficient. A compilation of material, electronic and interfacial chemical properties is presented, which is considered relevant for quantum energy conversion. In spite of intricate problems existing within material chemistry, high quantum efficiencies for photocurrent generation (Eta

A ENNAOUI; S FIECHTER; C PETTENKOFER; N ALONSOVANTE; K BUKER; M BRONOLD; C HOPFNER; H TRIBUTSCH

1993-01-01

346

Nuclear Chemistry.  

ERIC Educational Resources Information Center

Provides a brief review of the latest developments in nuclear chemistry. Nuclear research today is directed toward increased activity in radiopharmaceuticals and formation of new isotopes by high-energy, heavy-ion collisions. (Author/BB)

Chemical and Engineering News, 1979

1979-01-01

347

Cooperative Chemistry  

NSDL National Science Digital Library

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

Allan A. Gahr

2003-02-01

348

Chemistry Notes  

ERIC Educational Resources Information Center

Several ideas are proposed for chemistry teachers to try in their classrooms. Subjects included are polymerization of acrylate, polymerization of styrene, conductivity, pollution, preparation of chlorine, redox equations, chemiluminescence, and molecular sieves. (PS)

School Science Review, 1973

1973-01-01

349

Chemistry Notes.  

ERIC Educational Resources Information Center

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)

School Science Review, 1981

1981-01-01

350

Catalytic Chemistry.  

ERIC Educational Resources Information Center

Describes an approach for making chemistry relevant to everyday life. Involves the study of kinetics using the decomposition of hydrogen peroxide by vegetable juices. Allows students to design and carry out experiments and then draw conclusions from their results. (JRH)

Borer, Londa; And Others

1996-01-01

351

Radioanalytical Chemistry  

NSDL National Science Digital Library

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.

Hardy, James K.

352

Green Chemistry  

NSDL National Science Digital Library

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.

Foundation, Wgbh E.

2011-03-21

353

Chemistry Tutorials  

NSDL National Science Digital Library

The California State University Stanislaus developed these interactive chemistry Web tutorials to assist college students in mass spectrometry, proton NMR chemical shifts, and more. With the many animations and figures, visitors will find assistance with the subtraction and absorption of light and with infrared absorption frequencies for numerous compounds. The titration tutorials simulate laboratory experiments without the hazards of dealing with chemicals. Students will also find a very informative lesson describing how to use Excel to record and analyze their chemistry data.

354

Stratospheric chemistry  

SciTech Connect

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.

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

1991-01-01

355

Study of the Thermal Diffusion Behavior of Alkane/Benzene Mixtures by Thermal Diffusion Forced Rayleigh Scattering Experiments and Lattice Model Calculations  

E-print Network

Study of the Thermal Diffusion Behavior of Alkane/Benzene Mixtures by Thermal Diffusion Forced mixtures of linear alkanes (heptane, nonane, undecane, tridecane, pentadecane, heptadecane) in benzene has and temperatures. The Soret coefficient ST of the alkane was found to be negative for these n-alkane

Luettmer-Strathmann, Jutta

356

n-Alkane evidence for the onset of wetter conditions in the Sierra Nevada, California (USA) at the mid-late Holocene transition, ~3.0 ka  

E-print Network

n-Alkane evidence for the onset of wetter conditions in the Sierra Nevada, California (USA: Sierra Nevada Paleoclimate Paleolimnology Plant n-alkanes Lake level Holocene n-Alkane biomarker inferred from marine and continental records in the eastern North Pacific region. Length distributions of n-alkane

Anderson, R. Scott

357

Lyotropic effects of alkanes and headgroup composition on the L03B1 -HII lipid liquid crystal phase transition : hydrocarbon packing versus intrinsic curvature  

E-print Network

761 Lyotropic effects of alkanes and headgroup composition on the L03B1 -HII lipid liquid crystal of mixed phospholipid headgroup composition and the addition of small amounts of alkane were examined relieved, for instance, by the addition of alkane. Without alkane, the L03B1 phase extended to high

Boyer, Edmond

358

Isolation and characterization of a novel n-alkane-degrading strain, Acinetobacter haemolyticus AR-46.  

PubMed

Strain AR-46, isolated and identified as Acinetobacter haemolyticus, evolutionally distant from the known hydrocarbon-degrading Acinetobacter spp., proved to have excellent long-chain n-alkane-degrading ability. This is the first detailed report on an n-alkane-utilizing strain belonging to this species. The preferred substrate is n-hexadecane, with an optimal temperature of 37 degrees C under aerobic conditions. Five complete and two partial open reading frames were sequenced and correlated with the early steps of monoterminal oxidation-initiated n-alkane mineralization. The encoded protein sequences and the arrangement of these genes displayed high similarity to those found in Acinetobacter sp. M-1, but AR-46 seemed to have only one alkane hydroxylase gene, with a completely different induction profile. Unique behaviour was also observed in n-alkane bioavailability. Substrate uptake occurred through the hydrophobic surface of n-alkane droplet-adhered cells possessing long, thick fimbriae, which were presumed to play a major role in n-alkane solubilization. A majority of the cells was in detached form, with thick, but short fimbriae. These free cells were permanently hydrophilic, unlike the cells of other Acinetobacter strains. PMID:17542497

Bihari, Zoltán; Pettkó-Szandtner, Aladár; Csanádi, Gyula; Balázs, Margit; Bartos, Péter; Kesseru, Péter; Kiss, István; Mécs, Imre

2007-01-01

359

Computational Chemistry for Chemistry Educators  

NSDL National Science Digital Library

In this paper we describe an ongoing project where the goal is to develop competence and confidence among chemistry faculty so they are able to utilize computational chemistry as an effective teaching tool. Advances in hardware and software have made research-grade tools readily available to the academic community. Training is required so that faculty can take full advantage of this technology, begin to transform the educational landscape, and attract more students to the study of science.

Sendlinger, Shawn C.; Metz, Clyde R.

360

Cometabolism of Methyl tertiary Butyl Ether and Gaseous n-Alkanes by Pseudomonas mendocina KR-1 Grown on C5 to C8 n-Alkanes  

PubMed Central

Pseudomonas mendocina KR-1 grew well on toluene, n-alkanes (C5 to C8), and 1° alcohols (C2 to C8) but not on other aromatics, gaseous n-alkanes (C1 to C4), isoalkanes (C4 to C6), 2° alcohols (C3 to C8), methyl tertiary butyl ether (MTBE), or tertiary butyl alcohol (TBA). Cells grown under carbon-limited conditions on n-alkanes in the presence of MTBE (42 ?mol) oxidized up to 94% of the added MTBE to TBA. Less than 3% of the added MTBE was oxidized to TBA when cells were grown on either 1° alcohols, toluene, or dextrose in the presence of MTBE. Concentrated n-pentane-grown cells oxidized MTBE to TBA without a lag phase and without generating tertiary butyl formate (TBF) as an intermediate. Neither TBF nor TBA was consumed by n-pentane-grown cells, while formaldehyde, the expected C1 product of MTBE dealkylation, was rapidly consumed. Similar Ks values for MTBE were observed for cells grown on C5 to C8 n-alkanes (12.95 ± 2.04 mM), suggesting that the same enzyme oxidizes MTBE in cells grown on each n-alkane. All growth-supporting n-alkanes (C5 to C8) inhibited MTBE oxidation by resting n-pentane-grown cells. Propane (Ki = 53 ?M) and n-butane (Ki = 16 ?M) also inhibited MTBE oxidation, and both gases were also consumed by cells during growth on n-pentane. Cultures grown on C5 to C8 n-alkanes also exhibited up to twofold-higher levels of growth in the presence of propane or n-butane, whereas no growth stimulation was observed with methane, ethane, MTBE, TBA, or formaldehyde. The results are discussed in terms of their impacts on our understanding of MTBE biodegradation and cometabolism. PMID:14660389

Smith, Christy A.; O'Reilly, Kirk T.; Hyman, Michael R.

2003-01-01

361

Cometabolism of methyl tertiary butyl ether and gaseous n-alkanes by Pseudomonas mendocina KR-1 grown on C5 to C8 n-alkanes.  

PubMed

Pseudomonas mendocina KR-1 grew well on toluene, n-alkanes (C5 to C8), and 1 degrees alcohols (C2 to C8) but not on other aromatics, gaseous n-alkanes (C1 to C4), isoalkanes (C4 to C6), 2 degrees alcohols (C3 to C8), methyl tertiary butyl ether (MTBE), or tertiary butyl alcohol (TBA). Cells grown under carbon-limited conditions on n-alkanes in the presence of MTBE (42 micromoles) oxidized up to 94% of the added MTBE to TBA. Less than 3% of the added MTBE was oxidized to TBA when cells were grown on either 1 degrees alcohols, toluene, or dextrose in the presence of MTBE. Concentrated n-pentane-grown cells oxidized MTBE to TBA without a lag phase and without generating tertiary butyl formate (TBF) as an intermediate. Neither TBF nor TBA was consumed by n-pentane-grown cells, while formaldehyde, the expected C1 product of MTBE dealkylation, was rapidly consumed. Similar Ks values for MTBE were observed for cells grown on C5 to C8 n-alkanes (12.95 +/- 2.04 mM), suggesting that the same enzyme oxidizes MTBE in cells grown on each n-alkane. All growth-supporting n-alkanes (C5 to C8) inhibited MTBE oxidation by resting n-pentane-grown cells. Propane (Ki = 53 micromoles) and n-butane (Ki = 16 micromoles) also inhibited MTBE oxidation, and both gases were also consumed by cells during growth on n-pentane. Cultures grown on C5 to C8 n-alkanes also exhibited up to twofold-higher levels of growth in the presence of propane or n-butane, whereas no growth stimulation was observed with methane, ethane, MTBE, TBA, or formaldehyde. The results are discussed in terms of their impacts on our understanding of MTBE biodegradation and cometabolism. PMID:14660389

Smith, Christy A; O'Reilly, Kirk T; Hyman, Michael R

2003-12-01

362

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

NASA Astrophysics Data System (ADS)

A method using thermal desorption sampling and analysis by 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 light alkanes and alkenes which are a major constituent of both exhausts, allowing for quantification of higher molecular weight alkanes from the abundance of CnH2n+1 fragment ions. Using this approach, the molar abundance of C12-C18 alkanes in diesel engine exhaust was found to be 75% that of the total C1-C4 alkylbenzene abundance. While the PTR-MS mass spectra of gasoline and diesel exhaust looked similar, the abundance of higher molecular weight compounds relative to that of C4-alkylbenzenes was much greater in diesel engine exhaust. 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 of larger organic compounds to urban air concentrations.

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

2013-07-01

363

CYP153A6, a Soluble P450 Oxygenase Catalyzing Terminal-Alkane Hydroxylation  

PubMed Central

The first and key step in alkane metabolism is the terminal hydroxylation of alkanes to 1-alkanols, a reaction catalyzed by a family of integral-membrane diiron enzymes related to Pseudomonas putida GPo1 AlkB, by a diverse group of methane, propane, and butane monooxygenases and by some membrane-bound cytochrome P450s. Recently, a family of cytoplasmic P450 enzymes was identified in prokaryotes that allow their host to grow on aliphatic alkanes. One member of this family, CYP153A6 from Mycobacterium sp. HXN-1500, hydroxylates medium-chain-length alkanes (C6 to C11) to 1-alkanols with a maximal turnover number of 70 min?1 and has a regiospecificity of ?95% for the terminal carbon atom position. Spectroscopic binding studies showed that C6-to-C11 aliphatic alkanes bind in the active site with Kd values varying from ?20 nM to 3.7 ?M. Longer alkanes bind more strongly than shorter alkanes, while the introduction of sterically hindering groups reduces the affinity. This suggests that the substrate-binding pocket is shaped such that linear alkanes are preferred. Electron paramagnetic resonance spectroscopy in the presence of the substrate showed the formation of an enzyme-substrate complex, which confirmed the binding of substrates observed in optical titrations. To rationalize the experimental observations on a molecular scale, homology modeling of CYP153A6 and docking of substrates were used to provide the first insight into structural features required for terminal alkane hydroxylation. PMID:16816194

Funhoff, Enrico G.; Bauer, Ulrich; García-Rubio, Inés; Witholt, Bernard; van Beilen, Jan B.

2006-01-01

364

Adhesion of epoxy primer to hydrotalcite conversion coated AA2024  

Microsoft Academic Search

Hydrotalcite-based (HT) conversion coatings are being developed as an environmentally benign alternative to chromate conversion coatings (CCC). Accelerated exposure tests were conducted on epoxy primed, HT-modified AA2024 to gauge service performance. HT-based conversion coatings did not perform as well as the CCC when used with an epoxy primer. The current HT chemistries are optimized for stand-alone corrosion protection, however additional

Robert Benton Leggat III

2002-01-01

365

On the large ?-hyperconjugation in alkanes and alkenes.  

PubMed

The conventional view that the ?CC and ?CH bonds in alkanes and unsaturated hydrocarbons are so highly localized that their non-steric interactions are negligible is scrutinized by the block-localized wavefunction (BLW) method. Even molecules considered conventionally to be "strain free" and "unperturbed" have surprisingly large and quite significant total ?-BLW-delocalization energies (DEs) due to their geminal and vicinal hyperconjugative interactions. Thus, the computed BLW-DEs (in kcal mol(-1)) for the antiperiplanar conformations of the n-alkanes (C(N)H(2N+2), N = 1-10) range from 11.6 for ethane to 82.2 for?n-decane and are 50.9 for cyclohexane and 91.0 for adamantane. Although ?-electron delocalization in unsaturated hydrocarbons usually is ignored, the ?-BLW-DEs (in kcal mol(-1)) are substantial, as exemplified by D2h ethylene (9.0), triplet D2d ethylene (16.4), allene (19.3), butadiene (19.0), hexatriene (28.3), benzene (28.1), and cyclobutadiene (21.1). While each individual geminal and vicinal hyperconjugative interaction between hydrocarbon ?-bonding and ?-antibonding orbitals tends to be smaller than an individual ? conjugative interaction (e.g., 10.2 kcal mol(-1) in anti-1,3-butadiene, the presence of many ?-hyperconjugative interactions (e.g., a total of 12 in anti-1,3-butadiene, see text), result in substantial total ?-stabilization energies (e.g., 19.0 kcal mol(-1) for butadiene), which may surpass those from the ? interactions. Although large in magnitude, ?-electron delocalization energies often are obscured by cancellation when two hydrocarbons are compared. Rather than being strain-free, cyclohexane, adamantane, and diamantane suffer from their increasing number of intramolecular 1,4-C…C repulsions resulting in elongated C-C bond lengths and reduced ?-hyperconjugation, compared to the (skew-free) antiperiplanar n-alkane conformers. Instead of being inconsequential, ?-bond interactions are important and merit consideration. PMID:24912591

Wu, Judy I-Chia; Wang, Changwei; McKee, William Chadwick; Schleyer, Paul von Ragué; Wu, Wei; Mo, Yirong

2014-06-01

366

Copper-Catalyzed Intermolecular Amidation and Imidation of Unactivated Alkanes  

PubMed Central

We report a set of rare copper-catalyzed reactions of alkanes with simple amides, sulfonamides, and imides (i.e., benzamides, tosylamides, carbamates, and phthalimide) to form the corresponding N-alkyl products. The reactions lead to functionalization at secondary C–H bonds over tertiary C–H bonds and even occur at primary C–H bonds. [(phen)Cu(phth)] (1-phth) and [(phen)Cu(phth)2] (1-phth2), which are potential intermediates in the reaction, have been isolated and fully characterized. The stoichiometric reactions of 1-phth and 1-phth2 with alkanes, alkyl radicals, and radical probes were investigated to elucidate the mechanism of the amidation. The catalytic and stoichiometric reactions require both copper and tBuOOtBu for the generation of N-alkyl product. Neither 1-phth nor 1-phth2 reacted with excess cyclohexane at 100 °C without tBuOOtBu. However, the reactions of 1-phth and 1-phth2 with tBuOOtBu afforded N-cyclohexylphthalimide (Cy-phth), N-methylphthalimide, and tert-butoxycyclohexane (Cy-OtBu) in approximate ratios of 70:20:30, respectively. Reactions with radical traps support the intermediacy of a tert-butoxy radical, which forms an alkyl radical intermediate. The intermediacy of an alkyl radical was evidenced by the catalytic reaction of cyclohexane with benzamide in the presence of CBr4, which formed exclusively bromocyclohexane. Furthermore, stoichiometric reactions of [(phen)Cu(phth)2] with tBuOOtBu and (Ph(Me)2CO)2 at 100 °C without cyclohexane afforded N-methylphthalimide (Me-phth) from ?-Me scission of the alkoxy radicals to form a methyl radical. Separate reactions of cyclohexane and d12-cyclohexane with benzamide showed that the turnover-limiting step in the catalytic reaction is the C–H cleavage of cyclohexane by a tert-butoxy radical. These mechanistic data imply that the tert-butoxy radical reacts with the C–H bonds of alkanes, and the subsequent alkyl radical combines with 1-phth2 to form the corresponding N-alkyl imide product. PMID:24405209

2015-01-01

367

Radiation Chemistry  

NASA Astrophysics Data System (ADS)

Ionizing radiation causes chemical changes in the molecules of the interacting medium. The initial molecules change to new molecules, resulting in changes of the physical, chemical, and eventually biological properties of the material. For instance, water decomposes to its elements H2 and O2. In polymers, degradation and crosslinking take place. In biopolymers, e.g., DNS strand breaks and other alterations occur. Such changes are to be avoided in some cases (radiation protection), however, in other cases they are used for technological purposes (radiation processing). This chapter introduces radiation chemistry by discussing the sources of ionizing radiation (radionuclide sources, machine sources), absorption of radiation energy, techniques used in radiation chemistry research, and methods of absorbed energy (absorbed dose) measurements. Radiation chemistry of different classes of inorganic (water and aqueous solutions, inorganic solids, ionic liquids (ILs)) and organic substances (hydrocarbons, halogenated compounds, polymers, and biomolecules) is discussed in concise form together with theoretical and experimental backgrounds. An essential part of the chapter is the introduction of radiation processing technologies in the fields of polymer chemistry, food processing, and sterilization. The application of radiation chemistry to nuclear technology and to protection of environment (flue gas treatment, wastewater treatment) is also discussed.

Wojnárovits, L.

368

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

DOEpatents

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.

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

1989-10-17

369

Effect of n-alkanes on asphaltene structuring in petroleum oils.  

PubMed

The interactions between asphaltenes and short- to medium-chain n-alkanes were studied using titration microcalorimetry and inverse chromatography. The exothermic heat effects observed upon mixing of asphaltenes and n-alkanes were interpreted in terms of assembling of the two types of compounds into mixed structures. We show that the energy of the interactions between n-alkanes and the asphaltene hydrocarbon chains is close to the energy of the interactions between the asphaltene chains. We propose that the latter interactions are responsible for the formation of the asphaltene aggregates and are the driving force of the aggregate assembly into higher structures. PMID:15896019

Stachowiak, Christian; Viguié, Jean-Romain; Grolier, Jean-Pierre E; Rogalski, Marek

2005-05-24

370

n Alkanes variability in the diazotrophic cyanobacterium Anabaena cylindrica in response to NaCl stress  

Microsoft Academic Search

n-Alkanes pattern in response to NaCl stress has been studied in the cyanobacterium Anabaena cylindrica. Saturated hydrocarbons were separated and identified by gas chromatography-mass spectrometry (GC-MS) using serially coupled\\u000a capillary column. Light chain n-alkanes in the range of C9–C17 (43%) and heavy chain n-alkanes in range of C17–C23 (34%) and C23–C31 (23%) were identified as the major components of total

Pratiksha Bhadauriya; Radha Gupta; Surendra Singh; Prakash Singh Bisen

2008-01-01

371

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

DOEpatents

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.

Crabtree, Robert H. (Bethany, CT); Brown, Stephen H. (East Haven, CT)

1989-01-01

372

(2/94)(1,2,8/95)(6,7/97)(10/98)(1,9-11/99) Neuman Chapter 2 Alkanes and Cycloalkanes  

E-print Network

(2/94)(1,2,8/95)(6,7/97)(10/98)(1,9-11/99) Neuman Chapter 2 0 Chapter 2 Alkanes and Cycloalkanes ************************************************************************************** I. Foundations 1. Organic Molecules and Chemical Bonding 2. Alkanes and Cycloalkanes 3. Haloalkanes)(6,7/97)(10/98)(1,9-11/99) Neuman Chapter 2 1 2: Alkanes and Cycloalkanes Preview 2-3 2.1 Alkanes 2-3 Structures of Alkanes (2.1A) 2

Reed, Christopher A.

373

Position: Assistant Professor of Chemistry, Physical Chemistry  

E-print Network

John Grey Position: Assistant Professor of Chemistry, Physical Chemistry Email: jkgrey@unm.edu Phone: 505.277.1658; Fax: 505.277.2609 Office: Clark Hall B70 Homepage: http://chemistry.unm.edu/faculty_web/jgrey Education B.S. in Chemistry, 1999, Michigan Technological University, Houghton, MI Ph.D. in Chemistry

374

CHEMISTRY 107-01 GENERAL CHEMISTRY I  

E-print Network

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

Findley, Gary L.

375

Surface diffusion of n-alkanes: Mechanism and anomalous behavior  

NASA Astrophysics Data System (ADS)

In this Letter, we investigate, using molecular dynamics simulations, the diffusion of n-octane and n-tetradecane on a graphite surface at 300 K under incomplete coverage condition. For both molecules, we observe that the lateral diffusion coefficient exhibits a ?-shape anomaly with surface coverage i.e., the diffusion coefficient increases with the increase in surface coverage until a critical surface coverage, beyond which the diffusion coefficient decreases. Moreover, for low surface coverages, the longer n-tetradecane molecule moves faster compared to the shorter n-octane molecule and for high surface coverages, the n-octane molecule moves faster. We develop a new theory to understand the surface diffusion of n-alkanes and show that D˜{r}/{ee2Np?R}.

Park, Jae Hyun; Aluru, N. R.

2007-10-01

376

Pairwise-additive hydrophobic effect for alkanes in water  

PubMed Central

Pairwise additivity of the hydrophobic effect is indicated by reliable experimental Henry's constants for a large number of linear and branched low-molecular-weight alkanes in water. Pairwise additivity suggests that the hydrophobic effect is primarily a local phenomenon and that the hydrophobic interaction may be represented by a semiempirical force field. By representing the hydrophobic potential between two methane molecules as a linear function of the overlap volume of the hydration layers, we find that the contact value of the hydrophobic potential (?0.72 kcal/mol) is smaller than that from quantum mechanics simulations (?2.8 kcal/mol) but is close to that from classical molecular dynamics (?0.5??0.9 kcal/mol). PMID:18599448

Wu, Jianzhong; Prausnitz, John M.

2008-01-01

377

Rate effects on layering of a confined linear alkane  

E-print Network

We perform drainage experiments of a linear alkane fluid (n-hexadecane) down to molecular thicknesses, and focus on the role played by the confinement rate. We show that molecular layering is strongly influenced by the velocity at which the confining walls are approached: under high enough shear rates, the confined medium behaves as a structureless liquid of enhanced viscosity for film thickness below $\\sim$10 nm. Our results also lead us to conclude that a rapidly confined film can be quenched in a metastable disordered state, which might be related with recent intriguing results on the shear properties of confined films produced at different rates [Zhu and Granick, Phys. Rev. Lett. {\\bf 93}, 096101 (2004)].

Lionel Bureau

2007-06-19

378

Kitchen Chemistry  

NSDL National Science Digital Library

There is a great deal of chemistry going on in every kitchen, even though most cooks may not be cognizant of the various interactions going on in the pot, wok, or oven. MIT's popular OpenCourseWare Initiative has recently made the contents of Dr. Patricia Christie's course on kitchen chemistry available on this site. Visitors to the site can download the syllabus, take in some assigned readings (and recipes), and look over the assignments. The assignments include investigations that involve emulsifiers, ice cream, peer teaching, and pancakes, among other things. The site also includes links to helpful readings, such as those on chocolate, the health benefits of capsicum, and the world of gluten. For people who wish to bring back the frayed connective tissue between chemistry and the culinary arts, this site is absolutely essential.

Christie, Patricia

2006-01-01

379

Chemistry & Industry  

NSDL National Science Digital Library

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.

1997-01-01

380

Chemistry Now  

NSDL National Science Digital Library

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.

2012-08-17

381

Chemistry & Industry  

NSDL National Science Digital Library

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.

2006-01-11

382

Characterization of the Medium- and Long-Chain n-Alkanes Degrading Pseudomonas aeruginosa Strain SJTD-1 and Its Alkane Hydroxylase Genes  

PubMed Central

A gram-negative aliphatic hydrocarbon-degrading bacterium SJTD-1 isolated from oil-contaminated soil was identified as Pseudomonas aeruginosa by comparative analyses of the 16S rRNA sequence, phenotype, and physiological features. SJTD-1 could efficiently mineralize medium- and long-chain n-alkanes (C12-C30) as its sole carbon source within seven days, showing the most optimal growth on n-hexadecane, followed by n-octadecane, and n-eicosane. In 36 h, 500 mg/L of tetradecane, hexadecane, and octadecane were transformed completely; and 2 g/L n-hexadecane was degraded to undetectable levels within 72 h. Two putative alkane-degrading genes (gene 3623 and gene 4712) were characterized and our results indicated that their gene products were rate-limiting enzymes involved in the synergetic catabolism of C12–C16 alkanes. On the basis of bioinformatics and transcriptional analysis, two P450 monooxygenases, along with a putative AlmA-like oxygenase, were examined. Genetically defective mutants lacking the characteristic alkane hydroxylase failed to degrade n-octadecane, thereby suggesting a different catalytic mechanism for the microbial transformation of alkanes with chain lengths over C18. PMID:25165808

Liu, Huan; Xu, Jing; Liang, Rubing; Liu, Jianhua

2014-01-01

383

/6582 Biophysical Chemistry Fall Biophysical Chemistry  

E-print Network

/6582 Biophysical Chemistry Fall 1 CHEM /6582 Biophysical Chemistry Course meeting place concepts in biophysical chemistry. You will develop an understanding of how thermodynamics, kinetics literature concerning the application of biophysical techniques to characterize biological molecules

Sherrill, David

384

Alkane oxidation with porphyrins and metal complexes thereof having haloalkyl side chains  

DOEpatents

Transition metal complexes of meso-haloalkylporphyrins are disclosed, wherein the haloalkyl groups contain 2 to 8 carbon atoms have been found to be highly effective catalysts for oxidation of alkanes and for the decomposition of hydroperoxides. 7 figs.

Wijesekera, T.; Lyons, J.E.; Ellis, P.E. Jr.; Bhinde, M.V.

1998-06-23

385

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

PubMed Central

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

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

2014-01-01

386

Translocation of alkane through graphene nanopore: A molecular dynamics simulation study  

NASA Astrophysics Data System (ADS)

The process of molecules translocation through nanopore is important to understand many interesting phenomena. Molecular dynamics simulations have been carried out to study the translocation of alkane through graphene nanopore. The results detail relative distance, average translation time, etc. The translocation process can be divided into three stages: finding-entering-moving through the nanopore. Alkane must climb an energy barrier in every stage. The dependence of translocation on chain length is also discussed. Shorter alkanes are easy to transport through the nanopore and the average translocation time is short when alkane translocates through nanopore one by one. Our simulations show a visualized translocation process, which can favor our understanding of this important process.

Li, Jun-Yin; Yang, Hua; Sheng, Yan-Zhen; Zhao, Xin-Ting; Sun, Miao

2015-02-01

387

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

NASA Astrophysics Data System (ADS)

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.

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

2013-03-01

388

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

PubMed

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

Masuda, Hisako; Shiwa, Yuh; Yoshikawa, Hirofumi; Zylstra, Gerben J

2014-01-01

389

Alkane oxidation with porphyrins and metal complexes thereof having haloalkyl side chains  

DOEpatents

Transition metal complexes of meso-haloalkylporphyrins, wherein the haloalkyl groups contain 2 to 8 carbon atoms have been found to be highly effective catalysts for oxidation of alkanes and for the decomposition of hydroperoxides.

Wijesekera, Tilak (Glen Mills, PA); Lyons, James E. (Wallingford, PA); Ellis, Jr., Paul E. (Downingtown, PA); Bhinde, Manoj V. (Boothwyn, PA)

1998-01-01

390

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

PubMed Central

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 alkane’s 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

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

2010-01-01

391

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.

392

Definition Chemistry  

E-print Network

1 · Definition · Chemistry · Factors · Mitigation MinE 422 Acid Rock Drainage Online `Gard Guide is a great source of information Terminology · acid rock drainage (ARD) · saline drainage (SD) · acid mine or acid and metalliferous drainage (AMD) · mining influenced water (MIW) · neutral mine drainage (NMD

Boisvert, Jeff

393

Chemistry Notes.  

ERIC Educational Resources Information Center

Presents procedures, experiments, demonstrations, teaching suggestions, and information on a variety of chemistry topics including, for example, inert gases, light-induced reactions, calculators, identification of substituted acetophenones, the elements, analysis of copper minerals, extraction of metallic strontium, equilibrium, halogens, and…

School Science Review, 1982

1982-01-01

394

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.

395

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.

396

Chemistry Notes.  

ERIC Educational Resources Information Center

Presents chemistry experiments, laboratory procedures, demonstrations, teaching suggestions, and classroom materials/activities. These include: game for teaching ionic formulas; method for balancing equations; description of useful redox series; computer programs (with listings) for water electrolysis simulation and for determining chemical…

School Science Review, 1983

1983-01-01

397

Chemistry Notes.  

ERIC Educational Resources Information Center

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)

School Science Review, 1978

1978-01-01

398

Common Chemistry  

NSDL National Science Digital Library

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.

Chemical Abstracts Service (CAS)

399

Chemistry Notes  

ERIC Educational Resources Information Center

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…

School Science Review, 1976

1976-01-01

400

Chlorine Chemistry  

NSDL National Science Digital Library

From poolcenter.com comes the Chlorine Chemistry Web site. Ten questions related to chlorine are answered such as What's the History of Chlorine, How Does Chlorine Work to Sanitize, and What Effect Does pH Have on Chlorine. Each is briefly explained in simple and non-technical language.

401

Bad Chemistry  

NSDL National Science Digital Library

This site from the Princeton Section of the American Chemical Society consists of articles about common chemical misconceptions along with examinations of the scientific explanation. The purpose of this page is to reveal common misconceptions in the field of Chemistry. The intended audience is secondary school students and their teachers. The page is at present just beginning, and additions are welcome.

Lehmann, Kevin; University, Princeton

402

Chemistry Notes.  

ERIC Educational Resources Information Center

Presents chemistry experiments, laboratory procedures, demonstrations, and classroom materials/activities. These include: experiments on colloids, processing of uranium ore, action of heat on carbonates; color test for phenols and aromatic amines; solvent properties of non-electrolytes; stereoscopic applications/methods; a valency balance;…

School Science Review, 1983

1983-01-01

403

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

PubMed Central

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

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

404

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

PubMed

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

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

2011-11-01

405

A smog chamber for studies of the reactions of terpenes and alkanes with ozone and OH  

Microsoft Academic Search

The design and performance of a smog chamber for the study of photochemical reactions under simulated environmental conditions is described. The chamber is thermostated for aerosol experiments, and it comprises a gas chromatographic sample enrichment system suitable for monitoring hydrocarbons at the ppbv level. By irradiating NOx\\/alkane-mixtures rate constants for the reaction of OH radicals with n-alkanes are determined from

F. Nolting; W. Behnke; C. Zetzsch

1988-01-01

406

An n-alkane proxy for the sedimentary input of submerged\\/floating freshwater aquatic macrophytes  

Microsoft Academic Search

Lipid analysis of aquatic plants from lakes on Mt. Kenya, E. Africa, revealed that non-emergent (submerged and floating-leaved) species displayed enhanced abundances of mid-chain length, C23 and C25n-alkanes. In contrast, the emergent aquatic plants had n-alkane distributions similar to those of the terrestrial vegetation, typically dominated by the long-chain length homologues (>C29). A proxy ratio, Paq, has been formulated to

K. J Ficken; B Li; D. L Swain; G Eglinton

2000-01-01

407

Hydrogen isotope ratios of recent lacustrine sedimentary n-alkanes record modern climate variability  

Microsoft Academic Search

Hydrogen isotope ratios were measured on n-alkanes (n-C12 to n-C31) extracted from recent lake surface sediments along a N-S European transect to test if modern climate variability is recorded in these biomarkers. ?D values of the n-alkanes are compared to ?D values of meteoric water from the IAEA-GNIP database spanning a range from ?119‰ in northern Sweden to ?41‰ in

D. Sachse; J. Radke; G. Gleixner

2004-01-01

408

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

NASA Astrophysics Data System (ADS)

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.

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

2014-01-01

409

Chemistry Gateways and Resources  

NSDL National Science Digital Library

The Chemistry Gateways and Resources collection is comprised of chemistry-related web portals, web sites, and individual digital resources pertaining to many areas of the discipline - general chemistry, organic and inorganic chemistry, physical chemistry, and others - and intended for a wide range of audiences: educators and learners, the general public, and chemistry research communities.

2008-03-14

410

Alkanes in flower surface waxes of Momordica cochinchinensis influence attraction to Aulacophora foveicollis Lucas (Coleoptera: Chrysomelidae).  

PubMed

Extraction, thin-layer chromatography, and gas chromatography-mass spectrophotometry analyses revealed 15 alkanes representing 97.14% of the total alkanes in the surface waxes of Momordica cochinchinensis Spreng flowers. Nonacosane was the prevailing alkane followed by hexatriacontane, nonadecane, heptacosane, and hentriacontane, accounting for 39.08%, 24.24%, 13.52%, 6.32%, and 5.12%, respectively. The alkanes from flower surface waxes followed by a synthetic mixture of alkanes mimicking alkanes of flower surface waxes elicited attraction of the female insect, Aulacophora foveicollis Lucas (Coleoptera: Chrysomelidae) between 2 and 10-?g/mL concentrations in a Y-shaped glass tube olfactometer bioassay under laboratory conditions. Synthetic nonadecane from 178.28-891.37 ng, heptacosane from 118.14-590.72 ng, and nonacosane at 784.73 ng showed attraction of the insect. A synthetic mixture of 534.82 ng nonadecane, 354.43 ng heptacosane, and 2,354.18 ng nonacosane elicited highest attraction of A. foveicollis. PMID:23949856

Mukherjee, A; Sarkar, N; Barik, A

2013-08-01

411

The influence of alkane chain length on the skin irritation potential of 1,2-alkanediols.  

PubMed

Several studies have reported that 1,2-alkanediols show increasing anti-microbial activity as their alkane chain length increases. However, there are no reports on the influence of alkane chain length on the skin irritation potential of 1,2-alkanediols. To investigate the influence of alkane chain length on the skin irritation potential of 1,2-alkanediols. The objective and subjective (sensory) skin irritation potentials of five 1,2-alkanediols - 1,2-butanediol, 1,2-pentanediol, 1,2-hexanediol, 1,2-octanediol and 1,2-decanediol - were evaluated. We also estimated percutaneous absorption by measuring in vitro skin penetration using a Franz diffusion cell system. Like anti-microbial activity, sensory irritation potential increased as alkane chain length increased, most likely due to increasing membrane interference and/or intrinsic toxicity of 1,2-alkanediols. 1,2-Hexanediol showed the lowest objective skin irritation potential, which increased when the alkane chain length decreased or increased. Furthermore, percutaneous absorption negatively correlated with the alkane chain length of 1,2-alkanediols. These results show that a lower skin absorption potential is not indicative of a low skin irritation potential. Our results suggest that the factors and processes involved in skin irritation potential are complex and that skin irritation potential is influenced by intrinsic toxicity and the potential for penetration or integration in the lipid bilayer. PMID:21585401

Lee, E; An, S; Cho, S-A; Yun, Y; Han, J; Hwang, Y K; Kim, H K; Lee, T R

2011-10-01

412

Photolytic formation of free radicals and their effect on hydrocarbon pyrolysis chemistry in a concentrated solar environment  

NASA Astrophysics Data System (ADS)

The objective of this research was two-fold: (1) to determine whether UV photons available in a concentrated solar environment can be used as a photolytic source to dissociate vapor phase acetone; and (2) to explore the effects of photolysis on rate and selectivity of free radical reactions. The experiments were conducted in a 1 kW arc image furnace/tubular flow reactor system. The results obtained conclusively showed that acetone readily photodissociates in a 1000 sun environment, leading to the formation of free radicals. It was further observed that Beer-Lambert law can be used to predict the rate of photolysis of acetone. Furthermore, acetone, when used as source of methyl radicals, sensitized the reaction chemistry of alkanes and alkenes at a temperature of 350 C. The methyl radicals from photolysis of acetone enhanced the cracking reactions of the alkanes yielding smaller alkanes and alkenes. When the initial hydrocarbon reactant was an alkene, a sensitization of the addition reaction was observed leading to formation of next higher alkene. To gain a theoretical insight into the reaction chemistry of alkanes, a numerical simulation model was developed to study the photosensitized decomposition of n-butane and the simulation results thus obtained were found to be in close agreement with experimental results.

Hunjan, M.; Mok, W. S.; Antal, M. J., Jr.

413

Photolytic formation of free radicals and their effect on hydrocarbon pyrolysis chemistry in a concentrated solar environment: Final report  

SciTech Connect

The objective of this research was two-fold: (1) to determine whether uv photons available in a concentrated solar environment can be used as a photolytic source to dissociate vapor phase acetone; and (2) to explore the effects of photolysis on rate and selectivity of free radical reactions. The experiments were conducted in a 1 kW arc image furnace/tubular flow reactor system. The results obtained conclusively showed that acetone readily photodissociates in a 1000 sun environment, leading to the formation of free radicals. It was further observed that Beer-Lambert law can be used to predict the rate of photolysis of acetone. Furthermore, acetone, when used as source of methyl radicals, sensitized the reaction chemistry of alkanes and alkenes at a temperature of 350/sup 0/C. The methyl radicals from photolysis of acetone enhanced the cracking reactions of the alkanes yielding smaller alkanes and alkenes. When the initial hydrocarbon reactant was an alkene, a sensitization of the addition reaction was observed leading to formation of next higher alkene. To gain a theoretical insight into the reaction chemistry of alkanes, a numerical simulation model was developed to study the photosensitized decomposition of n-butane and the simulation results thus obtained were found to be in close agreement with experimental results. 64 refs., 10 figs., 22 tabs.

Hunjan, M.; Mok, W.S.; Antal, M.J. Jr.

1987-01-01

414

Reconstitution of Plant Alkane Biosynthesis in Yeast Demonstrates That Arabidopsis ECERIFERUM1 and ECERIFERUM3 Are Core Components of a Very-Long-Chain Alkane Synthesis Complex[C][W  

PubMed Central

In land plants, very-long-chain (VLC) alkanes are major components of cuticular waxes that cover aerial organs, mainly acting as a waterproof barrier to prevent nonstomatal water loss. Although thoroughly investigated, plant alkane synthesis remains largely undiscovered. The Arabidopsis thaliana ECERIFERUM1 (CER1) protein has been recognized as an essential element of wax alkane synthesis; nevertheless, its function remains elusive. In this study, a screen for CER1 physical interaction partners was performed. The screen revealed that CER1 interacts with the wax-associated protein ECERIFERUM3 (CER3) and endoplasmic reticulum–localized cytochrome b5 isoforms (CYTB5s). The functional relevance of these interactions was assayed through an iterative approach using yeast as a heterologous expression system. In a yeast strain manipulated to produce VLC acyl-CoAs, a strict CER1 and CER3 coexpression resulted in VLC alkane synthesis. The additional presence of CYTB5s was found to enhance CER1/CER3 alkane production. Site-directed mutagenesis showed that CER1 His clusters are essential for alkane synthesis, whereas those of CER3 are not, suggesting that CYTB5s are specific CER1 cofactors. Collectively, our study reports the identification of plant alkane synthesis enzymatic components and supports a new model for alkane production in which CER1 interacts with both CER3 and CYTB5 to catalyze the redox-dependent synthesis of VLC alkanes from VLC acyl-CoAs. PMID:22773744

Bernard, Amélie; Domergue, Frédéric; Pascal, Stéphanie; Jetter, Reinhard; Renne, Charlotte; Faure, Jean-Denis; Haslam, Richard P.; Napier, Johnathan A.; Lessire, René; Joubès, Jérôme

2012-01-01

415

Chemistry 411/611 Inorganic Chemistry (2011)  

E-print Network

1 Chemistry 411/611 Inorganic Chemistry (2011) Instructor: Assistant Professor Mathew M. Maye Chemistry", 5th Edition, Freeman Press. Available at SU bookstore. The solution manual is optional. (Suggested for CHE611 Students pursuing Inorganic) Huheey, "Inorganic Chemistry: Principles of Structure

Mather, Patrick T.

416

Chemistry 675 (CHE 675) Advanced Organic Chemistry  

E-print Network

Chemistry 675 (CHE 675) Advanced Organic Chemistry Fall Semester 2011 Professor James Hougland675 is a graduate-level organic chemistry course that can be continued in the Spring semester as CHE685. These two courses focus on physical organic chemistry, which deals with the structure

Mather, Patrick T.

417

SYLLABUS for CHEMISTRY 2310 ORGANIC CHEMISTRY 1  

E-print Network

SYLLABUS for CHEMISTRY 2310 ORGANIC CHEMISTRY 1 Lectures: Monday, Wednesday and Friday 8:35 AM-9 · Highly Recommended Equipment: Turning Point Clicker · Highly Recommended: (1) "Organic Chemistry I Homework. · Class Objective: To study and begin to understand organic chemistry · Methods: Lectures

Simons, Jack

418

SYLLABUS CHEMISTRY 5710 ADVANCED ORGANIC CHEMISTRY LABORATORY  

E-print Network

SYLLABUS CHEMISTRY 5710 ADVANCED ORGANIC CHEMISTRY LABORATORY T, Th 9:40AM-10:30AM HEB 2006 understanding of organic chemistry. Methods: lectures, problem solving, laboratory experiments, laboratory reports, Prerequisites: Organic Chemistry II and Lab (Chem 2320 and Chem 2325) DATES (Approximate (except

Simons, Jack

419

ORGANIC CHEMISTRY UCLA Organic Chemistry Faculty  

E-print Network

ORGANIC CHEMISTRY UCLA Organic Chemistry Faculty perform research in molecular machines, exotic Harran, Professor and D.J. & J.M Cram Chair in Organic Chemistry: The Harran Group explores new, Distinguished Professor and Saul Winstein Chair in Organic Chemistry: The Houk Group develops qualitative rules

Levine, Alex J.

420

CHEMISTRY DEPARTMENT Chem 315 (Honors Organic Chemistry)  

E-print Network

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 are interested in taking CHE315 in the fall should register for Organic Chemistry CHE307 and apply for admission

Lawson, Catherine L.

421

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

Microsoft Academic Search

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

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

2001-01-01

422

Assessment of Gaussian3 and Density Functional Theories for Enthalpies of Formation of C1-C16 Alkanes  

Microsoft Academic Search

We have examined the performance of Gaussian-3 (G3) theory and six related methods for the calculation of enthalpies of formation of n-alkanes of up to 16 carbons and isoalkanes of up to 10 carbons. We have also examined the accuracy of the B3LYP density functional theory for the n-alkanes. The G3 enthalpies of formation of the n-alkanes have errors of

Paul C. Redfern; Peter Zapol; Larry A. Curtiss; Krishnan Raghavachari

2000-01-01

423

The use of n-alkanes for estimating feed intake in beef cows M Olivn, K Osoro  

E-print Network

The use of n-alkanes for estimating feed intake in beef cows M Oliván, K Osoro Instituto de Experimentación y P!omoció? Agraria, Apdo 13, 33300 Villaviciosa, Asturias, Spain N-alkanes technique gives with 1 M ethanolic KOH at 90°C during 14 hours and alkanes extraction with heptane was performed at hot

Paris-Sud XI, Université de

424

Conversion of methanol to 2,2,3-trimethylbutane (triptane) over indium(III) iodide.  

PubMed

InI3 is able to catalyze the conversion of methanol to a mixture of hydrocarbons at 200 degrees C with one highly branched alkane, 2,2,3-trimethylbutane (triptane), being obtained in high selectivity. The mechanism for InI3-catalyzed reactions appears to be basically the same as that proposed for the previously studied ZnI2-catalyzed system in which sequential methylation of olefins is followed by competing reactions of the resulting carbocation: proton loss to give the next olefin vs hydride transfer to give the corresponding alkane. Although the reaction conditions and typical triptane yields achievable with ZnI2 and InI3 are quite similar, the two systems behave rather differently in a number of important particulars, including significant differences between the detailed product distributions. Most of the differences in behavior can be ascribed to the stronger Lewis acidity of InI3, including the ability to activate some alkanes, the higher activity for methylation of arenes, and the fact that methanol conversion can be observed at somewhat lower temperatures with InI3 than with ZnI2. PMID:18047325

Bercaw, John E; Diaconescu, Paula L; Grubbs, Robert H; Hazari, Nilay; Kay, Richard D; Labinger, Jay A; Mehrkhodavandi, Parisa; Morris, George E; Sunley, Glenn J; Vagner, Patrick

2007-12-24

425

Computational chemistry  

NASA Technical Reports Server (NTRS)

With the advent of supercomputers, modern computational chemistry algorithms and codes, a powerful tool was created to help fill NASA's continuing need for information on the properties of matter in hostile or unusual environments. Computational resources provided under the National Aerodynamics Simulator (NAS) program were a cornerstone for recent advancements in this field. Properties of gases, materials, and their interactions can be determined from solutions of the governing equations. In the case of gases, for example, radiative transition probabilites per particle, bond-dissociation energies, and rates of simple chemical reactions can be determined computationally as reliably as from experiment. The data are proving to be quite valuable in providing inputs to real-gas flow simulation codes used to compute aerothermodynamic loads on NASA's aeroassist orbital transfer vehicles and a host of problems related to the National Aerospace Plane Program. Although more approximate, similar solutions can be obtained for ensembles of atoms simulating small particles of materials with and without the presence of gases. Computational chemistry has application in studying catalysis, properties of polymers, all of interest to various NASA missions, including those previously mentioned. In addition to discussing these applications of computational chemistry within NASA, the governing equations and the need for supercomputers for their solution is outlined.

Arnold, J. O.

1987-01-01

426

Effect of leaf litter degradation and seasonality on D/H isotope ratios of n-alkane biomarkers  

NASA Astrophysics Data System (ADS)

During the last decade, compound-specific hydrogen isotope analysis of plant leaf-wax and sedimentary n-alkyl lipids has become a promising tool for paleohydrological reconstructions. However, with the exception of several previous studies, there is a lack of knowledge regarding possible effects of early diagenesis on the ?D values of n-alkanes. We therefore investigated the n-alkane patterns and ?D values of long-chain n-alkanes from three different C3 higher plant species ( Acer pseudoplatanus L., Fagus sylvatica L. and Sorbus aucuparia L.) that have been degraded in a field leaf litterbag experiment for 27 months. We found that after an initial increase of long-chain n-alkane masses (up to ˜50%), decomposition took place with mean turnover times of 11.7 months. Intermittently, the masses of mid-chain n-alkanes increased significantly during periods of highest total mass losses. Furthermore, initially high odd-over-even predominances (OEP) declined and long-chain n-alkane ratios like n-C 31/C 27 and n-C 31/C 29 started to converge to the value of 1. While bulk leaf litter became systematically D-enriched especially during summer seasons (by ˜8‰ on average over 27 months), the ?D values of long-chain n-alkanes reveal no systematic overall shifts, but seasonal variations of up to 25‰ ( Fagus, n-C 27, average ˜13‰). Although a partly contribution by leaf-wax n-alkanes by throughfall cannot be excluded, these findings suggest that a microbial n-alkane pool sensitive to seasonal variations of soil water ?D rapidly builds up. We propose a conceptual model based on an isotope mass balance calculation that accounts for the decomposition of plant-derived n-alkanes and the build-up of microbial n-alkanes. Model results are in good agreement with measured n-alkane ?D results. Since microbial 'contamination' is not necessarily discernible from n-alkane concentration patterns alone, care may have to be taken not to over-interpret ?D values of sedimentary n-alkanes. Furthermore, since leaf-water is generally D-enriched compared to soil and lake waters, soil and water microbial n-alkane pools may help explain why soil and sediment n-alkanes are D-depleted compared to leaves.

Zech, Michael; Pedentchouk, Nikolai; Buggle, Björn; Leiber, Katharina; Kalbitz, Karsten; Markovi?, Slobodan B.; Glaser, Bruno

2011-09-01

427

Symmetry breaking and spectra of diphenyloctatetraene in n-alkanes  

NASA Astrophysics Data System (ADS)

One- and two-photon excitation spectra, as well as absorption and emission spectra of diphenyloctatetraene (DPOT) in n-alkanes are investigated at low temperatures. For DPOT in n-octane we report on the measurements of one-photon excitation and emission spectra and for DPOT in n-tetradecane (TD) on the measurements of one- and two-photon excitation spectra and emission spectra. The spectra are governed by the transitions between the electronic ground (S0) and the two lowest electronic excited singlet states (S1,S2). The interpretation is based on allowed transitions and transitions induced by the S1-S2 coupling due to Herzberg-Teller promoting modes or due to static lattice-induced distortions of DPOT. A single noncentrosymmetric site is observed for DPOT in n-octane. For DPOT in TD a centrosymmetric and a noncentrosymmetric site are reported. The analysis indicates that there is a dynamical equilibrium in the population of these two sites. The experimental data are quantitatively studied by comparison with simulated spectra. The simulation calculations are based on the coupling between nonadiabatic S1 and S2 states, harmonic modes, and suitable transition moments and line-shape functions. For DPOT in TD the calculations reveal an interesting interference pattern in the vibronic progressions observed in two-photon excitation spectra.

Walser, Daniel; Zumofen, Gert; Plakhotnik, Taras

2000-11-01

428

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

PubMed Central

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

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

2013-01-01

429

Secondary organic aerosol formation from intermediate-volatility organic compounds: cyclic, linear, and branched alkanes.  

PubMed

Intermediate volatility organic compounds (IVOCs) are an important class of secondary organic aerosol (SOA) precursors that have not been traditionally included in chemical transport models. A challenge is that the vast majority of IVOCs cannot be speciated using traditional gas chromatography-based techniques; instead they are classified as an unresolved complex mixture (UCM) that is presumably made up of a complex mixture of branched and cyclic alkanes. To better understand SOA formation from IVOCs, a series of smog chamber experiments was conducted with different alkanes, including cyclic, branched, and linear compounds. The experiments focused on freshly formed SOA from hydroxyl (OH) radical-initiated reactions under high-NO(x) conditions at typical atmospheric organic aerosol concentrations (C(OA)). SOA yields from cyclic alkanes were comparable to yields from linear alkanes three to four carbons larger in size. For alkanes with equivalent carbon numbers, branched alkanes had the lowest SOA mass yields, ranging between 0.05 and 0.08 at a C(OA) of 15 ?g m(-3). The SOA yield of branched alkanes also depends on the methyl branch position on the carbon backbone. High-resolution aerosol mass spectrometer data indicate that the SOA oxygen-to-carbon ratios were largely controlled by the carbon number of the precursor compound. Depending on the precursor size, the mass spectrum of SOA produced from IVOCs is similar to the semivolatile-oxygenated and hydrocarbon-like organic aerosol factors derived from ambient data. Using the new yield data, we estimated SOA formation potential from diesel exhaust and predict the contribution from UCM vapors to be nearly four times larger than the contribution from single-ring aromatics and comparable to that of polycyclic aromatic hydrocarbons after several hours of oxidation at typical atmospheric conditions. Therefore, SOA from IVOCs may be an important contributor to urban OA and should be included in SOA models; the yield data presented in this study are suitable for such use. PMID:22823284

Tkacik, Daniel S; Presto, Albert A; Donahue, Neil M; Robinson, Allen L

2012-08-21

430

Fatty aldehyde dehydrogenase multigene family involved in the assimilation of n-alkanes in Yarrowia lipolytica.  

PubMed

In the n-alkane assimilating yeast Yarrowia lipolytica, n-alkanes are oxidized to fatty acids via fatty alcohols and fatty aldehydes, after which they are utilized as carbon sources. Here, we show that four genes (HFD1-HFD4) encoding fatty aldehyde dehydrogenases (FALDHs) are involved in the metabolism of n-alkanes in Y. lipolytica. A mutant, in which all of four HFD genes are deleted (?hfd1-4 strain), could not grow on n-alkanes of 12-18 carbons; however, the expression of one of those HFD genes restored its growth on n-alkanes. Production of Hfd2Ap or Hfd2Bp, translation products of transcript variants generated from HFD2 by the absence or presence of splicing, also supported the growth of the ?hfd1-4 strain on n-alkanes. The FALDH activity in the extract of the wild-type strain was increased when cells were incubated in the presence of n-decane, whereas this elevation in FALDH activity by n-decane was not observed in ?hfd1-4 strain extract. Substantial FALDH activities were detected in the extracts of Escherichia coli cells expressing the HFD genes. Fluorescent microscopic observation suggests that Hfd3p and Hfd2Bp are localized predominantly in the peroxisome, whereas Hfd1p and Hfd2Ap are localized in both the endoplasmic reticulum and the peroxisome. These results suggest that the HFD multigene family is responsible for the oxidation of fatty aldehydes to fatty acids in the metabolism of n-alkanes, and raise the possibility that Hfd proteins have diversified by gene multiplication and RNA splicing to efficiently assimilate or detoxify fatty aldehydes in Y. lipolytica. PMID:25315778

Iwama, Ryo; Kobayashi, Satoshi; Ohta, Akinori; Horiuchi, Hiroyuki; Fukuda, Ryouichi

2014-11-28

431

Chemistry References  

NSDL National Science Digital Library

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 ...

Kim

2007-08-08

432

Electroanalytical chemistry  

SciTech Connect

Many of the most significant electroanalytical advances may still lie ahead, according to Allen J. Bard of the University of Texas at Austin. Listening to Bard's presentation at the Eastern Analytical Symposium last November, one could not help but come away with the impression that electroanalytical chemistry may be entering the most exciting era in its history. It is an era in which we will see electrochemistry in the gas and solid phases, electrochemical resolution on the order of angstroms (scanning tunneling electrochemistry), and electrochemical expert systems.

Borman, S.

1987-02-15

433

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.

434

CHEMISTRY CURRICULUM SEMESTER I  

E-print Network

CHEMISTRY CURRICULUM SEMESTER ­ I Chemistry-I: Physical principles (2:1) Atomic structure-state approximation, Arrhenius equation and collision theory and catalysis. SEMESTER ­ II Chemistry-II: Structure orbital theory: polyatomic molecules - Walsh diagram; Main group chemistry: periodic properties, chemistry

Srinivasan, N.

435

Leaf wax n-alkane distributions in and across modern plants: Implications for paleoecology and chemotaxonomy  

NASA Astrophysics Data System (ADS)

Long chain (C21 to C37) n-alkanes are among the most long-lived and widely utilized terrestrial plant biomarkers. Dozens of studies have examined the range and variation of n-alkane chain-length abundances in modern plants from around the world, and n-alkane distributions have been used for a variety of purposes in paleoclimatology and paleoecology as well as chemotaxonomy. However, most of the paleoecological applications of n-alkane distributions have been based on a narrow set of modern data that cannot address intra- and inter-plant variability. Here, we present the results of a study using trees from near Chicago, IL, USA, as well as a meta-analysis of published data on modern plant n-alkane distributions. First, we test the conformity of n-alkane distributions in mature leaves across the canopy of 38 individual plants from 24 species as well as across a single growing season and find no significant differences for either canopy position or time of leaf collection. Second, we compile 2093 observations from 86 sources, including the new data here, to examine the generalities of n-alkane parameters such as carbon preference index (CPI), average chain length (ACL), and chain-length ratios for different plant groups. We show that angiosperms generally produce more n-alkanes than do gymnosperms, supporting previous observations, and furthermore that CPI values show such variation in modern plants that it is prudent to discard the use of CPI as a quantitative indicator of n-alkane degradation in sediments. We also test the hypotheses that certain n-alkane chain lengths predominate in and therefore can be representative of particular plant groups, namely, C23 and C25 in Sphagnum mosses, C27 and C29 in woody plants, and C31 in graminoids (grasses). We find that chain-length distributions are highly variable within plant groups, such that chemotaxonomic distinctions between grasses and woody plants are difficult to make based on n-alkane abundances. In contrast, Sphagnum mosses are marked by their predominance of C23 and C25, chain lengths which are largely absent in terrestrial vascular plants. The results here support the use of C23 as a robust proxy for Sphagnum mosses in paleoecological studies, but not the use of C27, C29, and C31 to separate graminoids and woody plants from one another, as both groups produce highly variable but significant amounts of all three chain lengths. In Africa, C33 and C35 chain lengths appear to distinguish graminoids from some woody plants, but this may be a reflection of the differences in rainforest and savanna environments. Indeed, variation in the abundances of long n-alkane chain lengths may be responding in part to local environmental conditions, and this calls for a more directed examination of the effects of temperature and aridity on plant n-alkane distributions in natural environments.

Bush, Rosemary T.; McInerney, Francesca A.

2013-09-01

436

Anaerobic oxidation of short-chain alkanes in hydrothermal sediments: potential influences on sulfur cycling and microbial diversity  

PubMed Central

Short-chain alkanes play a substantial role in carbon and sulfur cycling at hydrocarbon-rich environments globally, yet few studies have examined the metabolism of ethane (C2), propane (C3), and butane (C4) in anoxic sediments in contrast to methane (C1). In hydrothermal vent systems, short-chain alkanes are formed over relatively short geological time scales via thermogenic processes and often exist at high concentrations. The sediment-covered hydrothermal vent systems at Middle Valley (MV, Juan de Fuca Ridge) are an ideal site for investigating the anaerobic oxidation of C1–C4 alkanes, given the elevated temperatures and dissolved hydrocarbon species characteristic of these metalliferous sediments. We examined whether MV microbial communities oxidized C1–C4 alkanes under mesophilic to thermophilic sulfate-reducing conditions. Here we present data from discrete temperature (25, 55, and 75°C) anaerobic batch reactor incubations of MV sediments supplemented with individual alkanes. Co-registered alkane consumption and sulfate reduction (SR) measurements provide clear evidence for C1–C4 alkane oxidation linked to SR over time and across temperatures. In these anaerobic batch reactor sediments, 16S ribosomal RNA pyrosequencing revealed that Deltaproteobacteria, particularly a novel sulfate-reducing lineage, were the likely phylotypes mediating the oxidation of C2–C4 alkanes. Maximum C1–C4 alkane oxidation rates occurred at 55°C, which reflects the mid-core sediment temperature profile and corroborates previous studies of rate maxima for the anaerobic oxidation of methane (AOM). Of the alkanes investigated, C3 was oxidized at the highest rate over time, then C4, C2, and C1, respectively. The implications of these results are discussed with respect to the potential competition between the anaerobic oxidation of C2–C4alkanes with AOM for available oxidants and the influence on the fate of C1 derived from these hydrothermal systems. PMID:23717305

Adams, Melissa M.; Hoarfrost, Adrienne L.; Bose, Arpita; Joye, Samantha B.; Girguis, Peter R.

2013-01-01

437

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

NASA Astrophysics Data System (ADS)

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.

Norris, Charlotte; Dungait, Jennifer; Quideau, Sylvie

2013-04-01

438

Effects of 4-hydroxynonenal on isolated hepatocytes. Studies on chemiluminescence response, alkane production and glutathione status.  

PubMed Central

The effect of 4-hydroxy-2,3-trans-nonenal, a diffusible product of lipid peroxidation, on isolated hepatocytes was evaluated with two non-invasive techniques measuring low-level chemiluminescence and alkane evolution. Oxygen-induced low-level chemiluminescence and ethane and n-pentane formation by hepatocytes is enhanced over 7-fold in the presence of 4-hydroxynonenal (2 mM). Glutathione-depleted hepatocytes show a higher increase than controls in both low-level chemiluminescence and alkane formation upon supplementation with 4-hydroxynonenal. The effects on both parameters are diminished by vitamin E pretreatment of rats and are absent under anaerobiosis. At variance with chemiluminescence and alkane formation, 4-hydroxynonenal does not elicit a concomitant increase in malonaldehyde or diene-conjugate formation. Addition of 4-hydroxynonenal to a suspension of hepatocytes causes a rapid loss of cellular glutathione in the form of a glutathione conjugate with the alkenal as observed with high-pressure liquid-chromatographic analysis. The reaction between glutathione and 4-hydroxynonenal proceeds also spontaneously in vitro at 1:1 stoichiometry. The cellular effects of 4-hydroxynonenal evaluated by low-level chemiluminescence and alkane formation are independent of the formation of a glutathione conjugate and seem to rely on the remaining not-bound 4-hydroxynonenal. The sensitivity of 4-hydroxynonenal-enhanced chemiluminescence and alkane formation to free-radical quenchers suggests the participation of a free-radical propagation process. PMID:6688523

Cadenas, E; Müller, A; Brigelius, R; Esterbauer, H; Sies, H

1983-01-01

439

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

PubMed Central

Summary Acinetobacter baylyi ADP1 was found to tolerate seawater and have a special ability of adhering to an oil–water interface of 10–80?µm 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

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

2012-01-01

440

Biogeographic Variation of Foliar n-Alkanes of Juniperus communis var. saxatilis Pallas from the Balkans.  

PubMed

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

Raj?evi?, Nemanja; Jana?kovi?, Pedja; Dodoš, Tanja; Teševi?, Vele; Marin, Petar D

2014-12-01

441

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

PubMed Central

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

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

2011-01-01

442

Numerical and experimental studies of ethanol flames and autoignition theory for higher alkanes  

NASA Astrophysics Data System (ADS)

In order to enhance the fuel efficiency of an engine and to control pollutant formation, an improved understanding of the combustion chemistry of the fuels at a fundamental level is paramount. This knowledge can be gained by developing detailed reaction mechanisms of the fuels for various combustion processes and by studying combustion analytically employing reduced-chemistry descriptions. There is a need for small detailed reaction mechanisms for alkane and alcohol fuels with reduced uncertainties in their combustion chemistry that are computationally cheaper in multidimensional CFD calculations. Detailed mechanisms are the starting points in identifying reduced-chemistry descriptions of combustion processes to study problems analytically. This research includes numerical, experimental and analytical studies. The first part of the dissertation consists of numerical and experimental studies of ethanol flames. Although ethanol has gained popularity as a possible low-pollution source of renewable energy, significant uncertainties remain in its combustion chemistry. To begin to address ethanol combustion, first a relatively small detailed reaction mechanism, commonly known as the San Diego Mech, is developed for the combustion of hydrogen, carbon monoxide, formaldehyde, methane, methanol, ethane, ethylene, and acetylene, in air or oxygen-inert mixtures. This mechanism is tested for autoignition, premixed-flame burning velocities, and structures and extinction of diffusion flames and of partially premixed flames of many of these fuels. The reduction in uncertainties in the combustion chemistry can best be achieved by consistently updating a reaction mechanism with reaction rate data for the elementary steps based on newer studies in literature and by testing it against as many experimental conditions as available. The results of such a testing for abovementioned fuels are reported here along with the modifications of reaction-rate parameters of the most important elementary steps and the addition and deletion of a few key steps relevant to these tests. A mechanism developed in such a hierarchical way starting with simpler fuels such as hydrogen and carbon monoxide to the fuels with one and two carbon atoms has reduced uncertainties in the combustion chemistry of a fuel. This reaction mechanism, consisting of 137 reactions among 30 species, provides a robust building block upon which an ethanol mechanism is developed. The San Diego Mech is extended for ethanol combustion by adding 55 new reactions and 6 new species. Specifically, 33 reactions are added that involve C 2H5OH or one of the three isomers produced by abstraction of an H atom from it, CH3CHOH, CH2CH2OH and CH3CH2O, and 22 reactions are added that involve acetaldehyde or one of the two isomers produced by abstraction of H from it, CH2CHO and CH3CO. Ethanol combustion is investigated on the basis of a new reaction mechanism, thus developed, consisting of 192 elementary steps among 36 species, augmented by 53 additional steps and 14 additional species to address the formation of the oxides of nitrogen and 43 steps and 7 species to address formation of compounds involving three carbon atoms. The mechanism is tested against shock-tube autoignition-delay data, laminar burning velocities, counterflow diffusion-flame extinction and measurements of structures of counterflow partially premixed and diffusion flames. Measurements on ethanol-air flames at a strain rate of 100 s-1, employing prevaporized ethanol with a mole fraction of 0.3 in a nitrogen carrier stream, were made for the pure diffusion flame and for a partially premixed flame with a fuel-side equivalence ratio of 2.3 and involved thermocouple measurements of temperature profiles and determination of concentration profiles of C2H5OH, CO, CO2, H2, H2O, O2, N2, CH4, C2H6 and C2H2+C 2H4 by gas chromatographic analysis of samples withdrawn through fine quartz probes. Computational investigations also were made of profiles of oxides of nitrogen and other potential pollutants in similar partially premixed flames of etha

Saxena, Priyank

443

Conversational scene analysis  

E-print Network

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 ...

Basu, Sumit

2002-01-01

444

Iso-branched semifluorinated alkanes in Langmuir monolayers.  

PubMed

A series of semifluorinated n-alkanes (SFAs), of the general formula: (CF3)2CF(CF2)6(CH2)nH (in short iF9Hn), n = 11-20 have been synthesized and employed for Langmuir monolayer characterization. Surface pressure and electric surface potential measurements were performed in addition to Brewster angle microscopy results, which enabled both direct visualization of the monolayers structure and estimation of the monolayer thickness at different stages of compression. Our paper was aimed at investigating the influence of the iso-branching of the perfluorinated fragment of the SFA molecule on the surface behavior of these molecules at the air/water interface. It occurred that iF9 SFAs with the number of carbon atoms in the hydrogenated moiety from 11 to 20 are capable of Langmuir monolayer formation. Monolayers from iF9H11 to iF9H13 are instable, whereas those formed by iF9 SFAs with longer hydrogenated chains form stable films at the free surface of water. As compared to SFAs containing perfluorinated chain in a normal arrangement, iso-branched molecules have a greater tendency to aggregate. Lower stability of monolayers formed by iF9 SFAs as compared to F10 SFAs originated from the surface nucleation observed in BAM images, even at the very initial stages of compression. The dipole moment vector for iso-branched SFAs was found to be virtually aligned with the main axis of the molecule, contrary to F10 SFAs, where the dipole moment vector was calculated to be tilted with respect to the main molecular axis. Quantitative Brewster angle microscopy measurements (relative reflectivity experiments) enabled us to monitor the changes of monolayer thickness at different stages of monolayer compression. PMID:16545838

Broniatowski, M; Dynarowicz-?atka, P

2006-07-15

445

Energy conversion & storage program. 1995 annual report  

SciTech Connect

The 1995 annual report discusses laboratory activities in the Energy Conversion and Storage (EC&S) Program. The report is divided into three categories: electrochemistry, chemical applications, and material applications. Research performed in each category during 1995 is described. Specific research topics relate to the development of high-performance rechargeable batteries and fuel cells, the development of high-efficiency thermochemical processes for energy conversion, the characterization of new chemical processes and complex chemical species, and the study and application of novel materials related to energy conversion and transmission. Research projects focus on transport-process principles, chemical kinetics, thermodynamics, separation processes, organic and physical chemistry, novel materials and deposition technologies, and advanced methods of analysis.

Cairns, E.J.

1996-06-01

446

Direct Conversion of Energy.  

ERIC Educational Resources Information Center

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…

Corliss, William R.

447

Conversations in Child Care  

MedlinePLUS

Conversations in Child Care Health & Safety Notes One of the measures of excellence in child care is the quality of the conversations ... listened to and respected. To encourage conversation in child care: • Ask open-ended questions: Ask questions that require ...

448

ENERGY CONVERSION Spring 2011  

E-print Network

: Topics in Renewable/Sustainable Energy Conversion An engineering design project will be assigned1 ENSC 461 ENERGY CONVERSION Spring 2011 Instructor: Dr. Majid Bahrami 4372 Email will analyze thermal systems and energy conversion devices on the basis of the laws of thermodynamics. A main

Bahrami, Majid

449

Lyopolymorphism in binary systems of tetrapalladomesogenes in linear alkanes by Fourier transform far infrared spectroscopy and polmicroscopic methods  

Microsoft Academic Search

Dependence of displaying of lyotropic nematic polymorphism in binary systems tetranuclear palladium organyl\\/linear alkane from the ratio of number of carbon atoms of aliphatic mesogene substituents and alkane molecule was shown by the method of polmicroscopic analysis of contact preparates. For the first time it has been shown that two phases in nematic region could be resolved not only by

Vladimir Vatagin; Nadezhda Usol'Tseva; Klaus Praefcke; Alla Bronnikova

1997-01-01

450

Solvent-free synthesis of C10 and C11 branched alkanes from furfural and methyl isobutyl ketone.  

PubMed

Our best results jet: C10 and C11 branched alkanes, with low freezing points, are synthesized through the aldol condensation of furfural and methyl isobutyl ketone from lignocellulose, which is then followed by hydrodeoxygenation. These jet-fuel-range alkanes are obtained in high overall yields (?90%) under solvent-free conditions. PMID:23757334

Yang, Jinfan; Li, Ning; Li, Guangyi; Wang, Wentao; Wang, Aiqin; Wang, Xiaodong; Cong, Yu; Zhang, Tao

2013-07-01

451

Identification of phenylcycloparaffin alkanes and other monoaromatics in Green River shale by gas chromatography-mass spectrometry (GC-MS)  

Microsoft Academic Search

Analysis of an aromatics fraction confirmed the presence of 1 diaromatic and 23 monoaromatic hydrocarbons, including 10 phenyl(cyclohexyl)alkanes, 5 alkylbenzenes, 2 benzomonocycloparaffins, 3 benzodicycloparaffins, 2 benzocycloparaffins, 1 benzotricycloparaffin, and 1 naphthalenemonocycloparaffin. Substituted phenyl(cyclohexyl)- or (cyclopentyl)alkanes make up more than 50 percent of the total monoaromatics identified in Green River shale.

E. J. Gallegos

1973-01-01

452

Reveal of small alkanes and isomers using calculated core and valence binding energy spectra and total momentum cross sections  

E-print Network

The present study revealed quantum mechanically that the C1s binding energy spectra of the small alkanes (upto six carbons) provide a clear picture of isomeric chemical shift in linear alkanes and branched isomers, whereas the valence binding energy spectra contain more sensitive information regarding the length of the carbon chains. Total momentum cross sections of the alkanes exhibit the information of the chain length as well as constitutional isomers of the small alkanes. The C1s binding energies of small alkanes (including isomers) are position specific and the terminal carbons have the lowest energies. The length of an alkane chain does not apparently affect the C1s energies so that the terminal carbons (289.11 eV) of pentane are almost the same as those of hexane. The valence binding energy spectra of the alkanes are characterized by inner valence and outer valence regions which are separated by an energy gap at approximately 17 eV. The intensities of the total momentum cross sections of the alkanes ar...

Yang, Zejin

2013-01-01

453

Draft Genome Sequences of Three Smithella spp. Obtained from a Methanogenic Alkane-Degrading Culture and Oil Field Produced Water  

PubMed Central

Two draft genomes affiliated with Smithella spp. were obtained from a methanogenic alkane-degrading enrichment culture by single-cell sorting and metagenome contig binning, and a third was obtained by single-cell sorting of oil field produced water. Two genomes contained putative assABC genes encoding alkylsuccinate synthase, indicating genetic potential for fumarate activation of alkanes. PMID:25342693

Tan, BoonFei; de Araújo e Silva, Renata; Rozycki, Trent; Nesbø, Camilla

2014-01-01

454

C and dD compositions of n-alkanes from modern angiosperms and conifers: An experimental set up  

E-print Network

d13 C and dD compositions of n-alkanes from modern angiosperms and conifers: An experimental set up n-alkanes from 3 angiosperm and 2 conifer species from a semi-desert natural environment. The d13 C to Ã?212) throughout the 2005 growing season. Like the other angiosperm species, Betula pendula was D

Tipple, Brett

455

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

NASA Astrophysics Data System (ADS)

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.

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

2012-12-01

456

On the solubility of long n-alkanes in water at room temperature  

NASA Astrophysics Data System (ADS)

Ferguson et al. [A.L. Ferguson, P.G. Debenedetti, A.Z. Panagiotopoulos, J. Phys. Chem. B 113 (2009) 6405] did not find any evidence of a water-induced chain collapse for n-alkanes smaller than n-docosane: extended conformations are thermodynamically preferred. Using a simple geometric description of the different conformations of n-eicosane, reliable values of the reversible work to create a suitable cavity in water and to switch on alkane-water van der Waals attractions have been calculated. There is no chain collapse because the gain of attractive alkane-water interactions overwhelms in magnitude the loss in configurational/translational entropy of water molecules associated with the increase in the solvent-excluded volume on passing from a spherical shape to an elongated spherocylindrical one.

Graziano, Giuseppe

2011-08-01

457

The low temperature phase transition in octane and its possible generalisation to other n-alkanes  

NASA Astrophysics Data System (ADS)

A neutron powder diffraction study of three n-alkanes, octane, nonane and pentadecane, down to 2 K is presented. The temperature dependence of the octane diffraction pattern reveals a solid state phase transition between 40 and 55 K, which involves a doubling of the unit cell in the b direction, the space group remaining P 1¯. Confirmation of the phase transition, which results in a doubling of the number of crystallographically inequivalent methyl groups, is sought in the published NMR, tunnelling data and neutron scattering, vibrational data. Density functional theory and force field techniques are used to simulate spectroscopic data based on the measured structures. While no unequivocal evidence is found in spectroscopic data, the published data does not rule out the existence of energetically inequivalent methyl groups. Indeed close inspection of the spectroscopic data for other n-alkanes suggests that the phase transition may be common to many alkanes.

Neumann, M. A.; Johnson, M. R.; Radaelli, P. G.

2001-05-01

458

Preferred orientations and stability of medium length n-alkanes solidified in mesoporous silicon  

SciTech Connect

The n-alkanes C{sub 16}H{sub 34}, C{sub 17}H{sub 36}, C{sub 19}H{sub 40}, and C{sub 25}H{sub 52} have been imbibed and solidified in mesoporous, crystalline silicon with a mean pore diameter of 10 nm. The structures and phase sequences have been determined by x-ray diffractometry. Apart from a reduction and the hysteresis of the melting-freezing transition, we find a set of six discrete orientation states (''domains'') of the confined alkane crystals with respect to the lattice of the silicon host. The growth process responsible for the domain selection is interpreted as a nanoscale version of the Bridgman technique known from single-crystal growth. Oxidation of the pore walls leads to extrusion of the hydrocarbons upon crystallization, whereas the solidified n-alkanes investigated in nonoxidized, porous silicon are thermodynamically stable.

Henschel, A.; Hofmann, T.; Huber, P.; Knorr, K. [Technische Physik, Universitaet des Saarlandes, D-66041 Saarbruecken (Germany)

2007-02-15

459

The rate-limiting step for alkane dehydrogenation in zeolite H-ZSM-5.  

SciTech Connect

We have carried out a computational study of protolytic cracking, dehydrogenation, and H/D exchange of ethane, propane, and butane using a cluster model of H-ZSM-5. Our previous work has demonstrated that quantum-chemical techniques can give quantitatively accurate activation energies for alkane cracking in zeolites [1]. Experimental kinetic studies have shown that the apparent activation energies for cracking and H/D exchange decrease with n-alkane chain length, while for dehydrogenation the energies increase [2,3]. Our goal is to study the dependence of the activation energy on the alkane chain length in these reactions and to understand why the dehydrogenation reaction behaves so differently.

Zygmunt, S. A.; Bootz, B. L.; Miller, A. W.; Curtiss, L. A.; Iton, L. E.

2000-11-01

460

Chemistry of the outer planets  

NASA Technical Reports Server (NTRS)

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.

Scattergood, Thomas W.

1992-01-01

461

What is Chemistry?  

NSDL National Science Digital Library

Provided by Kiwi Web Chemistry & New Zealand, the "What is Chemistry?" Web site offers a wealth of chemistry information and links. Visitors can read the definition of and link to other sites on inorganic chemistry, organic chemistry, analytical chemistry, physical chemistry, stoichiometry, nuclear chemistry, alchemy, and biochemistry. Other pages of the site explore acids and bases, redox reductions, equations, moles, periodic tables, and more. This extensive and interesting site does a good job of clearly explaining some difficult concepts as well as providing educators and students a good source of other quality sites containing similar content.

Campbell, Allan

462

Combustion chemistry  

SciTech Connect

This research is concerned with the development and use of sensitivity analysis tools to probe the response of dependent variables to model input variables. Sensitivity analysis is important at all levels of combustion modeling. This group`s research continues to be focused on elucidating the interrelationship between features in the underlying potential energy surface (obtained from ab initio quantum chemistry calculations) and their responses in the quantum dynamics, e.g., reactive transition probabilities, cross sections, and thermal rate coefficients. The goals of this research are: (i) to provide feedback information to quantum chemists in their potential surface refinement efforts, and (ii) to gain a better understanding of how various regions in the potential influence the dynamics. These investigations are carried out with the methodology of quantum functional sensitivity analysis (QFSA).

Brown, N.J. [Lawrence Berkeley Laboratory, CA (United States)

1993-12-01

463

Hydrogen isotopes in n-alkanes of tree leaves and needles: experimental studies with ecophysiological, ecosystem, climate, and dust-related applications  

E-print Network

Hydrogen isotopes in n-alkanes of tree leaves and needles: experimental studies leaf-wax normal-alkanes have attracted recent interest as a biomarker for paleo-climate reconstruction as they are easily identified in sediments and robust to alteration. However, the isotope applications of n-alkanes

Tipple, Brett

464

Hypothetical Thermodynamic Properties: Vapor Pressures and Vaporization Enthalpies of the Even n-Alkanes from C78 to C92 at T ) 298.15 K by  

E-print Network

Hypothetical Thermodynamic Properties: Vapor Pressures and Vaporization Enthalpies of the Even n-Alkanes and vapor pressures of the n-alkanes from T ) (298.15 to 540) K for heneicosane to dononacontane. The vapor" extended corresponding states principle (CSP) which uses n-alkane input parameters based on the works

Chickos, James S.

465

Langmuir films of normal-alkanes on the surface of liquid mercury Department of Physics, Bar-Ilan University, Ramat-Gan 52900, Israel  

E-print Network

Langmuir films of normal-alkanes on the surface of liquid mercury H. Kraack Department of Physics films of n-alkanes (CH3CHn 2CH3 , denote Cn) on mercury was studied for lengths 10 n 50, using surface surface-normal molecular orientation is invariably found, alkanes on mercury are always oriented surface

Pershan, Peter S.

466

Localized diffusive motion on two different time scales in solid alkane nanoparticles This article has been downloaded from IOPscience. Please scroll down to see the full text article.  

E-print Network

Localized diffusive motion on two different time scales in solid alkane nanoparticles This article.1209/0295-5075/91/66007 Localized diffusive motion on two different time scales in solid alkane nanoparticles S.-K. Wang1(a) , E motion in solid nano- to bulk-sized particles of the alkane n-C32H66. The crystalline

Montfrooij, Wouter

467

Evidence for Alkane Coordination to an Electron-Rich Uranium Center Ingrid Castro-Rodriguez, Hidetaka Nakai, Peter Gantzel, Lev N. Zakharov, Arnold L. Rheingold, and  

E-print Network

Evidence for Alkane Coordination to an Electron-Rich Uranium Center Ingrid Castro, California 92093-0358 Received August 14, 2003; E-mail: kmeyer@ucsd.edu Metal-alkane complexes are believed significant progress to elucidate the fundamental nature of metal-alkane interactions, detailed structural

Meyer, Karsten

468

Effects of Molecular Geometry on the STM Image Contrast of Methyl-and Bromo-Substituted Alkanes and Alkanols on Graphite  

E-print Network

Effects of Molecular Geometry on the STM Image Contrast of Methyl- and Bromo-Substituted Alkanes microscopy (STM) images have been collected for a series of substituted alkanes and alkanols that form previously for molecules in which -OH, -Br, and -CH3 groups were located in terminal positions of alkane

Goddard III, William A.

469

Hypothetical Thermodynamic Properties: Vapor Pressures and Vaporization Enthalpies of the Even n-Alkanes from C40 to C76 at T ) 298.15 K by  

E-print Network

Hypothetical Thermodynamic Properties: Vapor Pressures and Vaporization Enthalpies of the Even n-Alkanes in combination with earlier work to evaluate the vaporization enthalpies and vapor pressures of these n-alkanes as the number of carbon atoms exceeds sixty. Introduction The n-alkanes serve as excellent standards

Chickos, James S.

470

A simple model for dense phases of two-dimensional hard rods and its application to mono-and bidisperse alkanes physisorbed  

E-print Network

- and bidisperse alkanes physisorbed on graphite Fi. Hentschke, L. Askadskaya, and J. P. Rabe Max tunneling microscopy experiments on dense monolayers of highly ordered alkane chains physisorbed on graphite theoretical results to structural transitions within dense monolayers formed by alkanes on graphite

Peters, Achim

471

Catalyst performance of novel Pt/Mg(Ga)(Al)O catalysts for alkane dehydrogenation Georges Siddiqi, Pingping Sun, Vladimir Galvita, Alexis T. Bell *  

E-print Network

Catalyst performance of novel Pt/Mg(Ga)(Al)O catalysts for alkane dehydrogenation Georges Siddiqi 28 June 2010 Accepted 29 June 2010 Available online 10 August 2010 Keywords: Ethane Propane Alkane/Pt = 5.4. The addition of hydrogen to the feed resulted in a peak in activity with respect to H2/alkane

Bell, Alexis

472

Calculation of Phase Coexistence Properties and Surface Tensions of n-Alkanes with Grand-Canonical Transition-Matrix Monte Carlo Simulation and Finite-Size Scaling  

E-print Network

Calculation of Phase Coexistence Properties and Surface Tensions of n-Alkanes with Grand densities and vapor pressures of select n-alkanes. Surface tension values for butane, hexane, and octane developed n-alkane force fields, the exponential-6 model overestimates the surface tension relative

Singh, Jayant K.

473

Determining diet composition on complex swards using n-alkanes and long-chain fatty alcohols.  

PubMed

We conducted an experiment to quantify the accuracy of methods based on n-alkanes and long-chain fatty alcohols for determining the diet composition of animals grazing complex swards. We cut forage from two indigenous vegetation communities, a Molinia caerulea-dominated grassland and a Calluna vulgaris-dominated dwarf-shrub community, and offered it to mature ewes in different ratios in a zero-grazing experiment. Nine dietary categories were identified within the forage offered: Molinia caerulea, Festuca spp., Juncus effusus, Carex spp., Calluna vulgaris, Erica tetralix, Vaccinium myrtillus, and dead grass. Samples of each of these categories together with fecal samples from each individual animal were analyzed for n-alkane and long-chain fatty alcohol concentrations. We analyzed the data using optimization software to minimize the sum of squares differences in the proportional profiles of n-alkanes and fatty alcohols in the diet and feces. Different combinations of n-alkane and fatty alcohols were investigated to assess which gave the most accurate measures of diet composition from the fecal profile. The most accurate estimates were obtained using combinations of the n-alkanes C25, C29, C31, and C33 and the long-chain fatty alcohols 1-C24-ol, 1-C28-ol, and 1-C30-ol, and these gave values for Lin's concordance correlation coefficient between estimated and actual values of >0.98. Our results demonstrate that n-alkanes and long-chain fatty alcohols can be used to estimate several components within the diet of animals grazing complex swards. Diet composition information obtained using this methodology has wide-ranging applications in terms of the assessment of the impact of grazing animals on particular ecosystems or the quantification of nutrient supply to the animal from different selection choices. PMID:17069381

Fraser, M D; Theobald, V J; Moorby, J M

2006-10-01

474

n-Alkane assimilation and tert-butyl alcohol (TBA) oxidation capacity in Mycobacterium austroafricanum strains.  

PubMed

Mycobacterium austroafricanum IFP 2012, which grows on methyl tert-butyl ether (MTBE) and on tert-butyl alcohol (TBA), the main intermediate of MTBE degradation, also grows on a broad range of n-alkanes (C2 to C16). A single alkB gene copy, encoding a non-heme alkane monooxygenase, was partially amplified from the genome of this bacterium. Its expression was induced after growth on n-propane, n-hexane, n-hexadecane and on TBA but not after growth on LB. The capacity of other fast-growing mycobacteria to grow on n-alkanes (C1 to C16) and to degrade TBA after growth on n-alkanes was compared to that of M. austroafricanum IFP 2012. We studied M. austroafricanum IFP 2012 and IFP 2015 able to grow on MTBE, M. austroafricanum IFP 2173 able to grow on isooctane, Mycobacterium sp. IFP 2009 able to grow on ethyl tert-butyl ether (ETBE), M. vaccae JOB5 (M. austroaafricanum ATCC 29678) able to degrade MTBE and TBA and M. smegmatis mc2 155 with no known degradation capacity towards fuel oxygenates. The M. austroafricanum strains grew on a broad range of n-alkanes and three were able to degrade TBA after growth on propane, hexane and hexadecane. An alkB gene was partially amplified from the genome of all mycobacteria and a sequence comparison demonstrated a close relationship among the M. austroafricanum strains. This is the first report suggesting the involvement of an alkane hydroxylase in TBA oxidation, a key step during MTBE metabolism. PMID:17347817

Lopes Ferreira, Nicolas; Mathis, Hugues; Labbé, Diane; Monot, Frédéric; Greer, Charles W; Fayolle-Guichard, Françoise

2007-06-01

475

Leaf-wax n-alkanes record the plant-water environment at leaf flush.  

PubMed

Leaf-wax n-alkanes (2)H/(1)H ratios are widely used as a proxy in climate reconstruction. Although the broad nature of the relationship between n-alkanes ?(2)H values and climate is appreciated, the quantitative details of the proxy remain elusive. To examine these details under natural environmental conditions, we studied a riparian broadleaf angiosperm species, Populus angustifolia, growing on water with a constant ?(2)H value and monitored the ?(2)H values of leaf-wax n-alkanes and of stem, leaf, stream, and atmospheric waters throughout the entire growing season. Here we found the ?(2)H values of leaf-wax n-alkanes recorded only a 2-wk period during leaf flush and did not vary for the 19 weeks thereafter when leaves remained active. We found ?(2)H values of leaf-wax n-alkanes of P. angustifolia record conditions earlier in the season rather than fully integrating the entire growing season. Using these data, we modeled precipitation ?(2)H values during the time of wax synthesis. We observed that the isotope ratios of this precipitation generally were (2)H-enriched compared with mean annual precipitation. This model provides a mechanistic basis of the often-observed (2)H-enrichment from the expected fractionation values in studies of broadleaf angiosperm leaf-wax ?(2)H. In addition, these findings may have implications for the spatial and temporal uses of n-alkane ?(2)H values in paleoapplications; when both plant community and growth form are known, this study allows the isolation of the precipitation dynamics of individual periods of the growing season. PMID:23359675

Tipple, Brett J; Berke, Melissa A; Doman, Christine E; Khachaturyan, Susanna; Ehleringer, James R

2013-02-12

476

Homology modeling and protein engineering of alkane monooxygenase in Burkholderia thailandensis MSMB121: in silico insights.  

PubMed

The degradation of hydrocarbons plays an important role in the eco-balancing of petroleum products, pesticides and other toxic products in the environment. The degradation of hydrocarbons by microbes such as Geobacillus thermodenitrificans, Burkhulderia, Gordonia sp. and Acinetobacter sp. has been studied intensively in the literature. The present study focused on the in silico protein engineering of alkane monooxygenase (ladA)-a protein involved in the alkane degradation pathway. We demonstrated the improvement in substrate binding energy with engineered ladA in Burkholderia thailandensis MSMB121. We identified an ortholog of ladA monooxygenase found in B. thailandensis MSMB121, and showed it to be an enzyme involved in an alkane degradation pathway studied extensively in Geobacillus thermodenitrificans. Homology modeling of the three-dimensional structure of ladA was performed with a crystal structure (protein databank ID: 3B9N) as a template in MODELLER 9v11, and further validated using PROCHECK, VERIFY-3D and WHATIF tools. Specific amino acids were substituted in the region corresponding to amino acids 305-370 of ladA protein, resulting in an enhancement of binding energy in different alkane chain molecules as compared to wild protein structures in the docking experiments. The substrate binding energy with the protein was calculated using Vina (Implemented in VEGAZZ). Molecular dynamics simulations were performed to study the dynamics of different alkane chain molecules inside the binding pockets of wild and mutated ladA. Here, we hypothesize an improvement in binding energies and accessibility of substrates towards engineered ladA enzyme, which could be further facilitated for wet laboratory-based experiments for validation of the alkane degradation pathway in this organism. PMID:24990796

Jain, Chakresh Kumar; Gupta, Money; Prasad, Yamuna; Wadhwa, Gulshan; Sharma, Sanjeev Kumar

2014-07-01

477

Pulse radiolysis of alkanes: A time-resolved electron paramagnetic resonance study  

SciTech Connect

Time-resolved spin-echo-detected electron paramagnetic resonance (EPR) was applied to examine short-lived alkyl radicals formed in pulse radiolysis of liquid alkanes. It was found that the ratio of yields of penultimate and interior radicals in n-alkanes at the instant of their generation is temperature-independent and is ca. 1.25 times greater than the statistical quantity. This higher-than-statistical production of penultimate radicals indicates that the fast ion molecule reactions involving radical cations are a significant route of radical generation. The analysis of spin-echo kinetics in n-alkanes suggests that the alkyl radicals are emissively polarized in spur reactions. this initial polarization rapidly increases with shortening of the aliphatic chain. Another finding is that a long-chain structure of these radicals results in much higher rate of Heisenberg spin exchange relative to the recombination rate. The relative yields of hydrogen abstraction and fragmentation for various branched alkanes are estimated. It is concluded that the fragmentation occurs prior to the formation of radicals in an excited precursor species. Effects of phenolic and alkene additives in radiolysis of n-alkanes are examined. It is demonstrated that phenoxy radicals are produced in dissociative capture of electrons and alkane holes. Another route is a reaction of phenols with free hydrogen atoms. A rapid transfer of singlet correlation from the geminate radical ion pairs is responsible for unusual polarization patterns in the phenoxy and cyclohexadienyl radicals. The significance of these results in the context of cross-linking in polyethylene and higher paraffins is discussed. 56 refs.

Shkrob, I.A.; Trifunac, A.D. [Argonne National Lab., IL (United States). Chemistry Division

1994-02-14

478

Leaf-wax n-alkanes record the plant–water environment at leaf flush  

PubMed Central

Leaf-wax n-alkanes 2H/1H ratios are widely used as a proxy in climate reconstruction. Although the broad nature of the relationship between n-alkanes ?2H values and climate is appreciated, the quantitative details of the proxy remain elusive. To examine these details under natural environmental conditions, we studied a riparian broadleaf angiosperm species, Populus angustifolia, growing on water with a constant ?2H value and monitored the ?2H values of leaf-wax n-alkanes and of stem, leaf, stream, and atmospheric waters throughout the entire growing season. Here we found the ?2H values of leaf-wax n-alkanes recorded only a 2-wk period during leaf flush and did not vary for the 19 weeks thereafter when leaves remained active. We found ?2H values of leaf-wax n-alkanes of P. angustifolia record conditions earlier in the season rather than fully integrating the entire growing season. Using these data, we modeled precipitation ?2H values during the time of wax synthesis. We observed that the isotope ratios of this precipitation generally were 2H-enriched compared with mean annual precipitation. This model provides a mechanistic basis of the often-observed 2H-enrichment from the expected fractionation values in studies of broadleaf angiosperm leaf-wax ?2H. In addition, these findings may have implications for the spatial and temporal uses of n-alkane ?2H values in paleoapplications; when both plant community and growth form are known, this study allows the isolation of the precipitation dynamics of individual periods of the growing season. PMID:23359675

Tipple, Brett J.; Berke, Melissa A.; Doman, Christine E.; Khachaturyan, Susanna; Ehleringer, James R.

2013-01-01

479

Increase of translatable mRNA for major microsomal proteins in n-alkane-grown Candida maltosa.  

PubMed Central

In an n-alkane-assimilating Candida sp., transfer from glucose- to n-alkane-containing medium induced changes in the microsomal proteins, and several distinctive polypeptides were demonstrated in the solubilized microsomal fraction derived from n-alkane-grown cells. Long-term-labeling and pulse-labeling experiments in vivo demonstrated the synthesis of the specific microsomal polypeptides. The polypeptides were synthesized as in vitro translation products directed by polyadenylated RNA extracted from n-alkane-grown cells. Two major polypeptides were partially purified from the microsomal fraction from n-alkane-grown cells, and antiserum was prepared in a rabbit. Immunoprecipitation of these two polypeptides was accompanied by an increase in the amount of translatable mRNA. The molecular weights of the polypeptides derived from long-term-labeling, pulse-labeling and in vitro translation experiments appeared to be identical. Images PMID:6501225

Sunairi, M; Watabe, K; Takagi, M; Yano, K

1984-01-01

480

Classification of vegetable oils according to their botanical origin using n-alkane profiles established by GC-MS.  

PubMed

n-Alkane profiles established by gas chromatography-mass spectrometry (GC-MS) were used to classify vegetable oils according to their botanical origin. The n-alkanes present in corn, grapeseed, hazelnut, olive, peanut and sunflower oils were isolated by means of alkaline hydrolysis followed by silica gel column chromatography of the unsaponifiable fractions. The n-alkane fraction was constituted mainly of n-alkanes in the range C8-C35, although only those most abundant (15 n-alkanes, from 21 to 35 carbon No.) were used as original variables to construct linear discriminant analysis (LDA) models. Ratios of the peak areas selected by pairs were used as predictors. All the oils were correctly classified according to their botanical origin, with assignment probabilities higher than 95%, using an LDA model. PMID:25148956

Troya, F; Lerma-García, M J; Herrero-Martínez, J M; Simó-Alfonso, E F

2015-01-15

481

FACULTY POSITION IN INORGANIC CHEMISTRY Department of Chemistry  

E-print Network

FACULTY POSITION IN INORGANIC CHEMISTRY Department of Chemistry Syracuse University The Department of Chemistry at Syracuse University invites applications for a tenure track faculty position at the Assistant Professor level in inorganic chemistry with specialization in materials chemistry (broadly defined

Doyle, Robert

482

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 are less important for Organic II than Organic I, but still incredibly useful at times). Weekly Recitation

483

Chemistry 224 Fall 2008 Honors General Chemistry  

E-print Network

Chemistry 224 Fall 2008 Honors General Chemistry Dr. Greg Williams Office hours: Onyx 182 Tu and Th regularly learn more chemistry and earn higher grades. Classroom office hours will be held in Onyx 171; there will be no formal presentations during office hours. There is also an office hour on Wednesday 2-3 pm in Onyx 182

Richmond, Geraldine L.

484

Consistency of plant specific n-alkane patterns in plaggen ecosystems  

NASA Astrophysics Data System (ADS)

Plaggen soils are an important soil type in north-western Europe that were formed by input of various vegetational sources during century-long plaggen (i.e. sod) application. This resulted in remarkably stable organic matter that appears to persists in spite of abandonment of large scale plaggen agriculture with the advent of artificial fertilizers in the early 20th century. Molecular characterization of the organic matter stored in plaggen soils, and in particular linkage to specific vegetation sources, could provide insight in yet poorly understood stabilization mechanisms and the fate of organic matter with ongoing land use change. Plant derived n-alkanes with chain-lenghts of 20-36 carbon atoms are usually well preserved in plaggen soils and could serve as important biomarkers for this purpose. Source appointment in plaggen soils is based on the use of concentration patterns of preserved n-alkanes with modern vegetation sources functioning as proxies. A crucial prerequisite is that patterns as observed in relevant present-day vegetation are representative and consistent. While this is generally assumed, to our knowledge it was never explicitly tested for plaggen soils. Therefore, we evaluated published n-alkane patterns of plant species and parts representative of past and current input to plaggen soils. We analyzed distribution patterns showing relative abundances in chain-length range C17-36 for various shrub, tree and grass species. Here we present and discuss the published n-alkane patterns in detail. We attempt to link variation in observed patterns to potential (systematic) sources such as geographical, temporal and methodological variations. Published distribution patterns derive from a variety of studies, characterized by differing laboratory techniques, environmental conditions etc. In spite of a surprisingly concise set of published n-alkane patterns, along with considerable scatter in the analyzed data, we did find meaningful clustering of n-alkanes allowing for clear distinction of input by shrubs, trees and grasses to plaggen soils. Indications of systematic variation were observed for ontogeny and according to spatial conditions among tree species, while effects by other variation sources were less pronounced. Our results emphasize the need for further extension and systematic clustering of available data on plant derived n-alkanes. Concurrently, they highlight that application of n-alkane biomarkers in paleo-environmental reconstructions of plaggen soils is challenging, but not prevented a-priori.

Kirkels, Frédérique; Jansen, Boris; Kalbitz, Karsten

2013-04-01

485

Intermediates of homogeneous deuterium exchange in alkanes catalyzed by Pt(II)  

Microsoft Academic Search

The rate constants and distribution of deuterated products of the H-D exchange in alkanes (C1–C8) have been measured for aqueous solutions of K2PtCl4. The reaction involves the intermediate formation of alkyl, 1,1-(carbene). 1,2-(olefin), 1,3-(cyclopropane) and 1,4-(cyclobutane) type hydrocarbon complexes. The selective attack of Pt(II) on the primary, secondary and tertiary C?H bonds in alkanes (1?1?0) is due to the predominance

A. I. Mustafin; A. A. Shteinman

1977-01-01

486

Monocarboxylic acids from oxidation of acyclic isoprenoid alkanes by Mycobacterium fortuitum  

NASA Technical Reports Server (NTRS)

Mycobacterium fortuitum utilizes certain stereoisomeric mixtures of individual multimethyl branched alkanes as sole carbon source, including 2,6(R), 10(S), 14(RS)-tetramethylhexadecane; 2,6(R), 10(S), 14(RS)-tetramethylheptadecane; 2,6(RS), 10(RS)-trimethyltetradecane, and 2,6(R), 10(S)-trimethylpentadecane. Products of oxidation isolated from the bacterial lipids were acids derived predominantly from oxidation of the isopropyl terminus of each alkane, except in the case of 2,6(RS), 10(RS)-trimethyltetradecane. With the latter, acids from oxidation at either terminus were detected in comparable proportions.

Cox, R. E.; Maxwell, J. R.; Myers, R. N.

1976-01-01

487

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

PubMed

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

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

2014-12-15

488

Mass effect on the Soret coefficient in n-alkane mixtures  

SciTech Connect

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.

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; Santamaría, 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

489

Regioselective alkane hydroxylation with a mutant CYP153A6 enzyme  

DOEpatents

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.

Koch, Daniel J.; Arnold, Frances H.

2013-01-29

490

Carboxylic acid reductase is a versatile enzyme for the conversion of fatty acids into fuels and chemical commodities  

PubMed Central

Aliphatic hydrocarbons such as fatty alcohols and petroleum-derived alkanes have numerous applications in the chemical industry. In recent years, the renewable synthesis of aliphatic hydrocarbons has been made possible by engineering microbes to overaccumulate fatty acids. However, to generate end products with the desired physicochemical properties (e.g., fatty aldehydes, alkanes, and alcohols), further conversion of the fatty acid is necessary. A carboxylic acid reductase (CAR) from Mycobacterium marinum was found to convert a wide range of aliphatic fatty acids (C6–C18) into corresponding aldehydes. Together with the broad-substrate specificity of an aldehyde reductase or an aldehyde decarbonylase, the catalytic conversion of fatty acids to fatty alcohols (C8–C16) or fatty alkanes (C7–C15) was reconstituted in vitro. This concept was applied in vivo, in combination with a chain-length-specific thioesterase, to engineer Escherichia coli BL21(DE3) strains that were capable of synthesizing fatty alcohols and alkanes. A fatty alcohol titer exceeding 350 mg·L?1 was obtained in minimal media supplemented with glucose. Moreover, by combining the CAR-dependent pathway with an exogenous fatty acid-generating lipase, natural oils (coconut oil, palm oil, and algal oil bodies) were enzymatically converted into fatty alcohols across a broad chain-length range (C8–C18). Together with complementing enzymes, the broad substrate specificity and kinetic characteristics of CAR opens the road for direct and tailored enzyme-catalyzed conversion of lipids into user-ready chemical commodities. PMID:23248280

Akhtar, M. Kalim; Turner, Nicholas J.; Jones, Patrik R.

2013-01-01

491

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

ERIC Educational Resources Information Center

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…

Kwiram, Alvin L.

492

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

SciTech Connect

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.

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

2009-03-09

493

Synthetic studies in nitrogen chemistry  

SciTech Connect

N,N-Bis(benzotriazolylmethyl)arylamines were obtained quantitatively from mixtures of benzotriazole, formaldehyde and the corresponding arylamine in refluxing toluene with azeotropic removal of water. Treatment of these adducts with Grignard reagents or sodium borohydride afforded symmetrically substituted N,N-dialkylarylamines in high yields. Unsymmetrically substituted N,N-dialkylarylamines could also be obtained by similar stepwise procedures. Sterically hindered N,N-bis(sec-butyl)arylamines were prepared by alkylations of the anions of the corresponding arylamines with 2-iodobutane. Chlorosulfonation of 2-nitroanisole gave 4-methoxy-3-nitrobenzene-sulfon-yl chloride, which was converted with N-butyl-(3-phenylpropyl)-amine into the corresponding benzenesulfonamide. Hydrolysis of the methoxy group and reduction of the nitro substituent of this benzene-sulfonamide, followed by diazotization and coupling with 2-naphthol, afforded N-butyl-N-(3-phenylpropyl)-4-hydroxy-3-(2-hydroxy-1-naphthyl)azobenzenesulfonamide. Medium-sized (7 and 8) benzosultams were synthesized by Friedel-Crafts cyclizations of w-phenylaklanesulfamoyl chlorides. New (benzotriazol-1-y)methyl derivatives of type Bt(1)CH[sub 2] X [Bt(1) = benzotriazol-1-yl] were prepared. [alpha]-(Benzotriazol-1-yl)acetophenone was converted to a number of interesting derivatives. Lithiation of 1-methylbenzotriazole followed by treatments with electrophiles gave various [alpha]-substituted 1-methylbenzotriazoles. Simple treatments of 2-alkylbenzotriazoles by LDA gave symmetrical [alpha],[beta]-bis-(benzotriazol-2-yl)alkanes sterospecifically as the [alpha],[alpha]-coupled products in high yields. A molecule [Bt(2)CH(CH[sub 3])CH(CH[sub 3])CH(CH[sub 3])CH(CH[sub 3])Bt(2)] [Bt(2) = benzotriazole-2-yl] with four asymmetric centers derived from four molecules of 2-ethylbenzotriazole was obtained as a single isomer. A new radical mechanism was first proposed to account for the chemistry of 2-alkylbenzotriazoles.

Wu, J.

1992-01-01

494

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

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.

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

2014-01-01

495

Reprint of "Stable hydrogen and carbon isotopic compositions of long-chain (C21-C33) n-alkanes and n-alkenes in insects"  

NASA Astrophysics Data System (ADS)

We report the molecular and stable isotopic (?D and ?13C) compositions of long-chain n-alkanes in common insects including the cabbage butterfly, swallowtail, wasp, hornet, grasshopper, and ladybug. Insect n-alkanes are potential candidates of the contamination of soil and sedimentary n-alkanes that are believed to be derived from vascular plant waxes. Long-chain n-alkanes (range C21-33; maximum C23-C29) are found to be abundant in the insects (31-781 ?g/dry g), with a carbon preference index (CPI) of 5.1-31.5 and an average chain length (ACL) of 24.9-29.3. The isotopic compositions (mean ± 1?, n = 33) of the n-alkanes are -195 ± 16‰ for hydrogen and -30.6 ± 2.4‰ for carbon. The insect n-alkanes are depleted in D by approximately 30-40‰ compared with wax n-alkanes from C3 (-155 ± 25‰) and C4 vascular plants (-167 ± 13‰), whereas their ?13C values fall between those of C3 (-36.2 ± 2.4‰) and C4 plants (-20.3 ± 2.4‰). Thus, the contribution of insect-derived n-alkanes to soil and sediment could potentially shift ?D records of n-alkanes toward more negative values and potentially muddle the assumed original C3/C4 balance in the ?13C records of the soil and sedimentary n-alkanes. n-Alkenes are also found in three insects (swallowtail, wasp and hornet). They are more depleted in D relative to the same carbon numbered n-alkanes (?Dn-alkene - ?Dn-alkane = -17 ± 16‰), but the ?13C values are almost identical to those of the n-alkanes (?13Cn-alkene - ?13Cn-alkane = 0.1 ± 0.2‰). These results suggest that these n-alkenes are desaturated products of the same carbon numbered n-alkanes.

Chikaraishi, Yoshito; Kaneko, Masanori; Ohkouchi, Naohiko

2013-06-01

496

Stable hydrogen and carbon isotopic compositions of long-chain (C21-C33) n-alkanes and n-alkenes in insects  

NASA Astrophysics Data System (ADS)

We report the molecular and stable isotopic (?D and ?13C) compositions of long-chain n-alkanes in common insects including the cabbage butterfly, swallowtail, wasp, hornet, grasshopper, and ladybug. Insect n-alkanes are potential candidates of the contamination of soil and sedimentary n-alkanes that are believed to be derived from vascular plant waxes. Long-chain n-alkanes (range C21-33; maximum C23-C29) are found to be abundant in the insects (31-781 ?g/dry g), with a carbon preference index (CPI) of 5.1-31.5 and an average chain length (ACL) of 24.9-29.3. The isotopic compositions (mean ± 1?, n = 33) of the n-alkanes are -195 ± 16‰ for hydrogen and -30.6 ± 2.4‰ for carbon. The insect n-alkanes are depleted in D by approximately 30-40‰ compared with wax n-alkanes from C3 (-155 ± 25‰) and C4 vascular plants (-167 ± 13‰), whereas their ?13C values fall between those of C3 (-36.2 ± 2.4‰) and C4 plants (-20.3 ± 2.4‰). Thus, the contribution of insect-derived n-alkanes to soil and sediment could potentially shift ?D records of n-alkanes toward more negative values and potentially muddle the assumed original C3/C4 balance in the ?13C records of the soil and sedimentary n-alkanes. n-Alkenes are also found in three insects (swallowtail, wasp and hornet). They are more depleted in D relative to the same carbon numbered n-alkanes (?Dn-alkene - ?Dn-alkane = -17 ± 16‰), but the ?13C values are almost identical to those of the n-alkanes (?13Cn-alkene - ?13Cn-alkane = 0.1 ± 0.2‰). These results suggest that these n-alkenes are desaturated products of the same carbon numbered n-alkanes.

Chikaraishi, Yoshito; Kaneko, Masanori; Ohkouchi, Naohiko

2012-10-01

497

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)

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.

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

2009-04-01

498

Trace Chemistry  

NASA Technical Reports Server (NTRS)

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 import