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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

Conversion of a lower alkane  

SciTech Connect

This patent describes a method for converting at least one feedstock alkane containing from one to three carbon atoms to a higher molecular weight hydrocarbon comprising: reacting the feedstock alkane with air to form a gaseous product mixture comprising carbon monoxide, hydrogen, and nitrogen and passing the gaseous product mixture through an elongated reactor packed with a bed of particles comprising a Fischer-Tropsch catalyst, maintained at a pressure in the range of from about 1 to about 50 pounds per square inch gauge and cooled to maintain the temperature therein in the range of from about 160C to about 240C, to thereby form a gaseous product stream comprising aliphatic hydrocarbon products having higher molecular weights than the feedstock alkane, the Fischer-Tropsch catalyst in the bed of particles of the reactor having increasing average activity for the conversion of synthesis gas from the inlet to the outlet of the reactor, the activity gradient being effected by dilution of Fischer-Tropsch catalyst particles with substantially inert particles, with the degree of dilution decreasing from the inlet to the outlet of the reactor.

Jezl, J.L.; Blanks, R.F.; Stasi, M.A.; Puskas, I.

1988-10-18

4

Conversion of a lower alkane  

SciTech Connect

A method is described for converting at least one feedstock alkane containing from one to three carbon atoms to a more valuable, higher molecular weight hydrocarbon, comprising: (a) passing a reaction mixture comprising the feedstock alkane and air at a pressure in the range of from about 1 to about 50 pounds per square inch gauge through an elongated first reactor packed with a bed of refractory particles. The particles are at a substantially higher temperature than is the incoming reaction mixture; and (b) passing the gaseous product mixture stream from the first reactor through an elongated second reactor packed with a bed of particles comprising a Fischer-Tropsch catalyst.

Jezl, J.L.; Blanks, R.F.; Stasi, M.A.; Puskas, I.

1987-03-31

5

Environmental Chemistry and Toxicology of Polychlorinated n Alkanes  

Microsoft Academic Search

\\u000a Polychlorinated-n-alkanes (PCAs) or chlorinated paraffins consist of C10to C30n-alkanes with chlorine content from 30% to 70% by mass. PCAs are used as high-temperature lubricants, plasticizers, flame\\u000a retardants, and additives in adhesives, paints, rubber, and sealants. This review presents the existing data on the environmental\\u000a chemistry and toxicology of PCAs and a preliminary exposure and risk assessment. There is limited information

G. T. Tomy; A. T. Fisk; J. B. Westmore; D. C. G. Muir

6

Catalytic conversion of light alkanes: Proof of concept stage  

SciTech Connect

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

Lyons, J.E.

1995-06-01

7

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.

8

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.

9

Silica-Supported Tantalum Clusters: Catalyst for Alkane Conversion  

SciTech Connect

Silica-supported tantalum clusters (on average, approximately tritantalum) were formed by the treatment, in either H{sub 2} or ethane, of adsorbed Ta(CH{sub 2}Ph){sub 5}; the supported catalyst is active for ethane conversion to methane and propane at 523 K, with the used catalyst containing clusters of the same average nuclearity as the precursor.

Nemana ,S.; Gates, B.

2006-01-01

10

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

11

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

12

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

SciTech Connect

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

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

1997-05-01

13

Catalytic conversion of light alkanes, Phase 1. Topical report, January 1990--January 1993  

SciTech Connect

The authors have found a family of new catalytic materials which, if successfully developed, will be effective in the conversion of light alkanes to alcohols or other oxygenates. Catalysts of this type have the potential to convert natural gas to clean-burning high octane liquid fuels directly without requiring the energy-intensive steam reforming step. In addition they also have the potential to upgrade light hydrocarbons found in natural gas to a variety of high value fuel and chemical products. In order for commercially useful processes to be developed, increases in catalytic life, reaction rate and selectivity are required. Recent progress in the experimental program geared to the further improvement of these catalysts is outlined.

NONE

1993-12-31

14

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

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

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

17

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

18

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

19

Experimental investigation of the atmospheric chemistry of aromatic hydrocarbons and long-chain alkanes. Final report  

SciTech Connect

The interaction of volatile organic compounds (VOCs) and oxides of nitrogen in the presence of sunlight leads to the formation of ozone and other manifestations of photochemical air pollution. There are, however, significant uncertainties in our knowledge of the products and mechanisms of the atmospheric reactions of alkanes and aromatic hydrocarbons, important constituents of ambient air in urban areas, with the hydroxyl (OH) radical. A series of product studies of the OH radical-initiated reactions of selected alkanes, ketones and alcohols have been carried out to obtain further insights into alkoxy radical isomerization. Product studies of the OH radical reaction with 4-methyl-2-pentanone, 2,6-dimethyl-4-heptanone, 2,4-dimethyl-2-pentanol and 3,5-dimethyl-3-hexanol in the presence of NOx have provided unambiguous evidence for alkoxy radical isomerization and these studies have provided rate constant ratios for the isomerization reaction versus alkoxy radical decomposition and reaction with O2.

Atkinson, R.; Arey, J.; Tuazon, E.C.; Aschmann, S.M.; Bridier, I.

1994-08-01

20

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.

21

Methane conversion to higher alkanes over ruthenium and cobalt loaded Zr{3}(PO{4}){4}  

NASA Astrophysics Data System (ADS)

The catalyst Ru-Co/Zr3(PO4)4 was synthesized by impregnation and was tested in the reaction of oligomerization of methane into higher hydrocarbon. The reaction was carried out using a two-steps procedure consisting of: - Methane adsorption. - Hydrogenation of the adsorbed entities and formation of higher hydrocarbons. The production of these alkanes extends from ethane to pentane and could schematically be described by the following pathways: CH4 rightleftharpoons (CH_x)_ads + (4-X)/2 H2 CH_x, CH_y rightleftharpoons C_nHm The results showed that addition of cobalt to ruthenium improved the global activity. This promoter effect was attributed to the synergy brought in by cobalt and to the formation of Ru-CO2+ species which are more active than ruthenium alone. These species were identified by EDX-STEM and XPS analyses.

Cheikhi, N.; Ziyad, M.

2005-03-01

22

Nanoparticle conversion chemistry: Kirkendall effect, galvanic exchange, and anion exchange  

NASA Astrophysics Data System (ADS)

Conversion chemistry is a rapidly maturing field, where chemical conversion of template nanoparticles (NPs) into new compositions is often accompanied by morphological changes, such as void formation. The principles and examples of three major classes of conversion chemical reactions are reviewed: the Kirkendall effect for metal NPs, galvanic exchange, and anion exchange, each of which can result in void formation in NPs. These reactions can be used to obtain complex structures that may not be attainable by other methods. During each kind of conversion chemical reaction, NPs undergo distinct chemical and morphological changes, and insights into the mechanisms of these reactions will allow for improved fine control and prediction of the structures of intermediates and products. Conversion of metal NPs into oxides, phosphides, sulphides, and selenides often occurs through the Kirkendall effect, where outward diffusion of metal atoms from the core is faster than inward diffusion of reactive species, resulting in void formation. In galvanic exchange reactions, metal NPs react with noble metal salts, where a redox reaction favours reduction and deposition of the noble metal (alloying) and oxidation and dissolution of the template metal (dealloying). In anion exchange reactions, addition of certain kinds of anions to solutions containing metal compound NPs drives anion exchange, which often results in significant morphological changes due to the large size of anions compared to cations. Conversion chemistry thus allows for the formation of NPs with complex compositions and structures, for which numerous applications are anticipated arising from their novel catalytic, electronic, optical, magnetic, and electrochemical properties.

Anderson, Bryan D.; Tracy, Joseph B.

2014-10-01

23

Light alkane conversion  

Microsoft Academic Search

This patent describes a process for the aromatization of an aliphatic feedstream. It comprises fluidizing finely divided solid particles in a combustion zone; charging oxygen-containing combustion gas and fuel to the combustion zone under combustion conditions; withdrawing a stream of finely divided particles from the combustion zone; flowing the withdrawn stream of finely divided particles above to a cracking\\/dehydrogenation zone;

M. N. Harandi; H. Owen

1991-01-01

24

Reducing the Degrees of Freedom in Chemistry Classroom Conversations  

ERIC Educational Resources Information Center

Five high-school chemistry teachers were asked to enact a lesson in which they posed a problem for which students were likely to generate solutions based on reasoning that was not aligned with accepted principles of chemistry. Four teachers selected a problem related to the stoichiometry of a reaction; the fifth chose a problem associated with…

Criswell, Brett A.

2012-01-01

25

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

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

Functionalization of paraffinic hydrocarbons by heterogeneous vapor-phase oxidation III. Conversion of the C sub 2 -C sub 7 alkane series  

SciTech Connect

A new promising area of research in the field of vapor-phase heterogeneous catalysis is the functionalization of paraffinic hydrocarbons. At present, the selective oxidation of {und n}-butane to maleic anhydride is the only process which is highly selective and operative on a commercial scale. The peculiar characteristics of selectivity, the basis for interest in this reaction, are principally related to the specific nature of the active phase, vanadyl pyrophosphate. This catalyst is the only active phase discovered which is truly selective: however, the activity/selectivity is strictly related to the method of preparation. The aim of this work is to investigate if it is possible to extend the utilization of a (VO){sub 2}P{sub 2}O{sub 7} catalyst highly active/selective in {und n}-butane. Propane conversion has been studied on V-P-O catalysts where low selectivities to methanol or acrylic acid were found and on Ce-Te-Mo-O oxides doped with CdX{sub 2} (X=F, C1) that give low yields of acrolein. The aims of this paper are to explore the mild oxidation of the other alkanes using the same active phase as for {und n}-butane and to obtain a better understanding of the transformation of {und n}-butane to maleic anhydride.

Centti, G.; Trifiro, F. (Department of Industrial Chemistry and Materials, Bologna (Italy))

1987-08-01

28

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...

29

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

E-print Network

: In this article, we describe a nonlinear threshold chemistry based on enzymatic inhibition and demonstrate howChemical Analog-to-Digital Signal Conversion Based on Robust Threshold Chemistry and Its Evaluation L. Koyner, and Rustem F. Ismagilov*, Department of Chemistry and Institute for Biophysical Dynamics

Ismagilov, Rustem F.

30

Superacid catalysis of light hydrocarbon conversion. Eleventh quarterly report, April 1, 1996--June 30, 1996  

SciTech Connect

The new catalyst Fe- and Mn-promoted sulfated zirconia is remarkably active for the low-temperature (even room temperature) isomerization of n-butane to give isobutane in the near absence of side products. Thus this catalyst offers excellent potential for practical application in this process. The catalyst is so active that it even converts smaller alkanes, including propane and ethane. The ethane conversion is orders of magnitude slower than the butane conversion, and the prospects for practical application with ethane are apparently negligible. However, the results for ethane conversion provide strong evidence that the alkane conversions proceed (at least under some conditions) by protonation of the alkane with the catalyst; thus the catalyst is comparable to superacids, and the chemistry is analogous to that occurring in superacid solutions. This insight will be useful in further improvement of the catalyst and the potential process for butane isomerization. The catalyst is active for alkane cracking at temperatures of typically 200-300{degrees}C, and evidence, summarized here, indicates that numerous reactions of alkanes begin as the catalyst protonates the alkane reactant. The kinetics data for this family of reactions fall on a linear compensation effect plot; such data for reactions that do not proceed via such a mechanism do not fall near the line representing the compensation effect. Thus the analysis of the kinetics data provides a good diagnostic tool for understanding the fundamental chemistry of the acid-catalyzed hydrocarbon conversions.

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

1996-12-31

31

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

Microsoft Academic Search

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

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

1982-01-01

32

Integration of Homogeneous and Heterogeneous Catalytic Processes for a Multi-step Conversion of Biomass: From Sucrose to Levulinic Acid, ?-Valerolactone, 1,4-Pentanediol, 2-Methyl-tetrahydrofuran, and Alkanes  

Microsoft Academic Search

The multi-step conversion of sucrose to various C5-oxygenates and alkanes was achieved by integrating various homogeneous and heterogeneous catalytic systems. We have confirmed\\u000a that the dehydration of sucrose to levulinic and formic acids is currently limited to about 30–40% in the presence of H2SO4, HCl, or Nafion NR50 in water. Performing the dehydration in the presence of a P(m-C6H4SO3Na)3 modified

Hasan Mehdi; Viktória Fábos; Róbert Tuba; Andrea Bodor; László T. Mika; István T. Horváth

2008-01-01

33

Superacid catalyzed coal conversion chemistry. Final technical report, September 1, 1983-September 1, 1986  

SciTech Connect

This research project involved the study of a raw comparatively mild coal conversion process. The goal of the project was to study model systems to understand the basic chemistry involved and to provide a possible effective pretreatment of coal which significantly improves liquefaction-depolymerization under mild conditions. The conversion process operates at relatively low temperatues (170/sup 0/C) and pressures and uses an easily recyclable, stable superacid catalysts (HF-BF/sub 3/). It consequently offers an attractive alternative to currently available processes. From the present studies it appears that the modification of coal structure by electrophilic alkylation and subsequent reaction of alkylated coal with HF-BF/sub 3/-H/sub 2/ system under mild conditions considerably improves the extractability of coal in pyridine and cyclohexane. On the other hand, nitration of coal and its subsequent reaction with HF-BF/sub 3/H/sub 2/ decreases the pyridine and cyclohexane extractability. Study of model compounds under conditions identical with the superacidic HF/BF/sub 3//H/sub 2/ system provided significant information about the basic chemistry of the involved cleavage-hydrogenation reactions.

Olah, G.A.

1986-01-01

34

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

35

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

PubMed Central

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

Kim, Hyun-Ha; Ogata, Atsushi

2011-01-01

36

PAPER www.rsc.org/greenchem | Green Chemistry A two-step approach for the catalytic conversion of glucose to  

E-print Network

PAPER www.rsc.org/greenchem | Green Chemistry A two-step approach for the catalytic conversion.1039/c004343e Lignocellulosic biomass is an attractive resource for producing transportation fuels of biomass to fuels or fuel additives. Glucose, the monomer of cellulose, is a good starting material

Bell, Alexis

37

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

NASA Astrophysics Data System (ADS)

A method of thermochemical energy conversion, transport, and storage research involving moderate and low temperature liquid phase systems employing Diels-Alder cycloaddition chemistry is described. Proposed as a heat storage system for solar and industrial waste heat, the system involves the meeting, in a reactor, of energy-depleted and energy-rich fluids. The poor fluid gains energy and goes through a chemical, endothermic dissociative change. The use of Diels-Alder reactions provides completely reversible chemical reactions for this application. The heated fluid can be retransported for storage or implementation as a heat source. The return reaction, releasing the stored heat, can be done spontaneously or in the presence of a catalyst such as Lewis acids. Attention is recommended for the Wentworth-Chen temperature of 250-300 C to minimize the system thermal degradation. Research in the synthesis of diene and dienophile candidate chemicals, into sealed tube and reaction kinetic techniques, and into NMR techniques for identifying further reaction candidates are discussed.

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

1982-12-01

38

The hydrodeoxygenation of bioderived furans into alkanes  

NASA Astrophysics Data System (ADS)

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

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

2013-05-01

39

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.

40

The fate of alkane radical cations in liquid and solid hydrocarbons. Time-resolved fluorescence detected magnetic resonance  

SciTech Connect

Time-resolved fluorescence detected magnetic resonance (FDMR) is used to observe alkane radical cations generated by electron radiolysis in liquid and solid alkane solutions. The ease of observation of the alkane radical cations (on the time scale of tens to hundreds of nanoseconds) depends strongly on the alkane under study as well as the conditions of temperature and concentration. Ion-molecule reactions such as proton transfer or H-atom transfer are responsible for the very transient nature of the alkane radical cations and possibly account for much of the diversity of hydrocarbon radiation chemistry.

Werst, D.W.; Bakker, M.G.; Trifunac, A.D. (Argonne National Lab., IL (USA))

1990-01-03

41

Superacid catalysis of light hydrocarbon conversion. Final report, August 26, 1993--August 26, 1996  

SciTech Connect

Motivated by the goal of finding improved catalysts for low- temperature conversion of light alkanes into fuel components or precursors of fuel components, the researchers have investigated sulfated zirconia and promoted sulfated zirconia for conversion of butane, propane, and ethane. Catalyst performance data for sulfated zirconia promoted with iron and manganese show that it is the most active noncorrosive, nonhalide catalyst known for n-butane isomerization, and it is an excellent candidate catalyst for new low- temperature n-butane isomerization processes to make isobutane, which can be converted by established technology into methyl t-butyl ether (MTBE). Various transition metals have been found to work as promoters of sulfated zirconia for n-butane isomerization. The combination of iron and manganese is the best known combination of promoters yet discovered. The iron- and manganese-promoted sulfated zirconia is also a catalyst for conversion of propane and of ethane. Ethane is converted into ethylene and butanes in the presence of the iron- and manganese-promoted sulfated zirconia; propane is also converted into butane, among other products. However, the activities of the catalyst for these reactions are orders of magnitude less than the activity for n-butane conversion, and there is no evidence that the catalyst would be of practical value for conversion of alkanes lighter than butane. The product distribution data for ethane and propane conversion provide new insights into the nature of the catalyst and its acidity. These data suggest the involvement of Olah superacid chemistry, whereby the catalyst protonates the alkane itself, giving carbonium ions (as transition states). The mechanism of protonation of the alkane may also pertain to the conversion of butane, but there is good evidence that the butane conversion also proceeds via alkene intermediates by conventional mechanisms of carbenium ion formation and rearrangement.

Gates, B.C.

1996-12-31

42

Force meets chemistry: Analysis of mechanochemical conversion in focal adhesions using fluorescence recovery after photobleaching  

Microsoft Academic Search

Mechanotransduction—the process by which mechanical forces are converted into changes of intracellular biochemistry—is critical for normal cell and tissue function. Integrins facilitate mechanochemical conversion by transferring physical forces from the extracellular matrix, across the cell surface, and to cytoskeletal- associated proteins within focal adhesions. It is likely that force alters biochemistry at these sites by altering molecular binding affinities of

Tanmay P. Lele; Charles K. Thodeti; Donald E. Ingber

2006-01-01

43

Exploratory study of coal-conversion chemistry. Final report, September 20, 1979-March 19, 1981  

SciTech Connect

Under Task A, the surprisingly rapid rates at which the strong carbon-carbon and carbon-oxygen central bonds in hydroxydiphenylmethanes and hydroxydiphenyl ethers are broken, under homogeneous conditions, in tetralin at 400/sup 0/C, have been quantitatively accounted for by a mechanism involving tautomerization to the weakly bonded keto forms followed by homolysis of the central bonds. These homogeneous decomposition mechanisms bear directly on the susceptibility of these linkages to homogeneously and heterogeneously catalyzed cleavage. Iron oxides, particularly Fe/sub 3/O/sub 4/, were found to be effective and selective catalysts for these same cleaveages. Relative catalyst effectiveness suggests that the mechanism of catalysis involves radical cation formation. Under Task B, the conversion of coal to benzene-soluble coal products in CO/H/sub 2/O systems displays a striking dependence on the pH of the starting aqueous phase. Thus below a starting pH of 12.6, the product benzene solubility is about 10% and steeply climbs to the 50% level under more basic conditions. This increase in conversion is paralleled by an increase in the reaction rate of the water-gas shift reaction. A series of runs was conducted using a catalytic amount (3000 to 6000 ppM) of water-soluble salts of several metals. Thus potassium or sodium salts of molybdate (Mo(VI)), dichromate (Cr(VI)), and permanganate (Mn(VII)) were found to be effective for the coal conversion. In addition, the catalytic activity of these salts also depends on the starting pH of the aqueous solution adjusted with dilute KOH or HC1 solutions. This indicates that despite the catalytic activity of metal-oxyanions, the changes in conversion are large over small pH changes; plots of conversion versus initial pH are S-shaped curves similar to common titration curves.

Ross, D.S.; McMillen, D.; Ogier, W.; Nguyen, Q.

1981-08-12

44

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

45

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

46

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

PubMed

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

Bordeaux, Mélanie; Galarneau, Anne; Drone, Jullien

2012-10-22

47

Nanorheology of Liquid Alkanes  

SciTech Connect

We report molecular dynamics simulations of liquid alkanes, squalane and tetracosane, confined between moving walls to which butane chains are tethered, effectively screening the details of the wall. As in an experiment, heat is removed by thermostatting the tethered molecules. Results obtained at high strain rates, typical of practical applications, suggest little or no difference between the bulk rheology and confined flow, and the occurrence of a high degree of slip at the wall-fluid interface at the conditions studied. At relatively low velocities and high densities, tetracosane shows the formation of fully-extended chains at certain wall spacings.

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

1997-09-01

48

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

49

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

50

One-pot conversion of sugar and sugar polyols to n-alkanes without C-C Dissociation over the Ir-ReOx /SiO2 catalyst combined with H-ZSM-5.  

PubMed

High (?95 % C) yields of n-hexane and n-pentane were obtained by hydrogenolysis of aqueous sorbitol and xylitol, respectively, at 413-443 K by using the Ir-ReOx /SiO2 catalyst combined with H-ZSM-5 as a cocatalyst and n-dodecane as a cosolvent. The direct production of n-hexane from glucose or cellobiose can be achieved by using the same system. The catalyst can be reused simply by the removal of the n-dodecane phase, which contains the product alkane, and the addition of fresh n-dodecane and substrate. PMID:23463694

Chen, Kaiyou; Tamura, Masazumi; Yuan, Zhenle; Nakagawa, Yoshinao; Tomishige, Keiichi

2013-04-01

51

Trends in Alkane Boiling Points  

NSDL National Science Digital Library

This activity is an investigation into the relationship between alkane length and boiling points. Students develop a mathematical model of this relationship and use it to make predictions and error analysis.

Woods, Paula

52

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

53

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

54

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.

55

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.

56

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

57

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

58

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

59

Evaporating Drops of Alkane Mixtures  

E-print Network

Alkane mixtures are model systems where the influence of surface tension gradients during the spreading and the evaporation of wetting drops can be easily studied. The surface tension gradients are mainly induced by concentration gradients, mass diffusion being a stabilising process. Depending on the relative concentration of the mixture, a rich pattern of behaviours is obtained.

Gu'ena, G; Poulard, C; Cazabat, Anne-Marie; Gu\\'{e}na, Geoffroy; Poulard, Christophe

2005-01-01

60

CONFORMATIONS OF ALKANES AND CYCLOALKANES  

E-print Network

reactions take place, be they reactions in living systems or reactions in test tubes, begins with a thorough of plants and animals but is toxic to them. Consequently, living systems have developed mechanisms to rid an animation showing the rotation about the O±O bond in hydrogen peroxide. #12;PROBLEM 3.1 Identify the alkanes

Ferreira, Márcia M. C.

61

Mechanism of methanol conversion over zeolite  

Microsoft Academic Search

Details of the reaction mechanisms of conversions of methanol to various alkanes and alkenes were investigated. A discussion of the autocatalytic phenomena of the conversion of methanol over ZSM-5 zeolite was included. The temperature dependence and acidity aspects of the reaction rate were discussed. Also the use of Nafion-H and heteropolyacids as catalysts of conversion was also included. A detailed

1983-01-01

62

Virial coefficients of model alkanes  

NASA Astrophysics Data System (ADS)

We report the results from Mayer-sampling Monte Carlo calculations of the virial coefficients of the united-atom TraPPE-UA model of normal alkanes. For alkane chain lengths from n =2 to 20 (where n is the number of carbon atoms), results are given for the virial coefficients B2, B3, and B4; results for B5 are given for chains up to length n =12; and results for B6 are given for chains of length n =2, 3, and 4. In all cases, values are given for temperatures ranging from 200 K to 2000 K in 20-50 K increments. The values are used to calculate the equation of state for butane and the pressure-density behavior is compared to experimental data at 350 and 550 K. Critical points are calculated for all systems and compared to simulation data previously taken for the same molecular model, and to experiment. The comparison with temperature is very good (within 1.5% for all chain lengths up to n =12), while the critical density is underestimated by about 5%-15% and the critical pressure is given within about 10%. The convergence behavior of the virial equation of state as applied across the n-alkane series is well characterized by corresponding states, meaning that the accuracy at a given density relative to the critical density does not deteriorate with increasing chain length.

Schultz, Andrew J.; Kofke, David A.

2010-09-01

63

Plant Cell Walls: Basics of Structure, Chemistry, Accessibility and the Influence on Conversion - Aqueous Pretreatment of Plant Biomass for Biological and Chemical Conversion to Fuels and Chemicals  

SciTech Connect

This book is focused on the pretreatment of biomass, a necessary step for efficient conversion of the plant cell wall materials to fuels and other products. Pretreatment is required because it is difficult to access, separate, and release the monomeric sugars comprising the biopolymers within the biomass that can be further upgraded to products through chemical processes such as aqueous phase reforming or biological routes such as fermentation of the sugars to ethanol This resistance to degradation or difficulty to release the monomers (mostly sugars) is commonly referred to as recalcitrance. There are many methods to overcome plant recalcitrance, but the underlying cause of the recalcitrance lies in the complex combination of chemical and structural features of the plant cell walls.

Davison, Brian H [ORNL; Davis, Dr. Mark F. [National Renewable Energy Laboratory (NREL); Parks, Jerry M [ORNL; Donohoe, Bryan [National Renewable Energy Laboratory (NREL)

2013-01-01

64

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

65

Environmental green chemistry as defined by photocatalysis.  

PubMed

Photocatalysis is efficient in several fields. Firstly, in selective mild oxidation: oxidation of gas and liquid hydrocarbons (alkanes, alkenes, cyclo-alkanes, aromatics) into aldehydes and ketons. Primary and secondary alcohols are also oxidized into their corresponding aldehydes or ketones. The high selectivity was ascribed to a photoactive neutral, atomic oxygen species. Once platinized (only 0.5wt.% Pt) titania may catalyze reactions involving hydrogen (deuterium-alkane isotopic exchange and alcohol dehydrogenation). For fine chemicals, high initial selectivities enable titania to address most of the twelve principles of "green chemistry", such as the synthesis of 4-tert-butyl-benzaldehyde, an important intermediate in perfume industry by direct selective oxidation of 4-tert-butyl-toluene with air. A new field recently appeared: thio-photocatalysis. Oxygen was replaced by sulfur, using H(2)S as a convenient and reactive source. For instance, the conversion of propene in 1-propanthiol was successfully obtained. The reaction was performed using either CdS or TiO(2). The latter was much more active than CdS. In environmental photocatalysis, titania becomes a total oxidation catalyst once in presence of water because of the photogeneration of OH radicals by neutralization of OH(-) surface groups by positive holes. Many toxic inorganic ions are oxidized in their harmless upper oxidized state. The total degradation of organic pollutants (pesticides, herbicides, insecticides, fungicides, dyes, etc. ...) is the main field of water photocatalytic decontamination. The UVA solar spectrum can de advantageously used as demonstrated by many campaigns performed in the solar pilot plant at the "Plataforma Solar de Almeria" (Spain). PMID:17532130

Herrmann, J-M; Duchamp, C; Karkmaz, M; Hoai, Bui Thu; Lachheb, H; Puzenat, E; Guillard, C

2007-07-31

66

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

67

Chemical analog-to-digital signal conversion based on robust threshold chemistry and its evaluation in the context of microfluidics-based quantitative assays.  

PubMed

In this article, 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 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 predetermined 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 (from 0.64 (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 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

2013-10-01

68

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

69

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

70

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

71

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

72

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

73

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

74

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

75

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

76

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

77

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

78

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

79

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

80

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

2014-10-20

81

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

82

Dissociation of alkane ionized molecules  

NASA Astrophysics Data System (ADS)

The subject of investigation is the fragmentation of variously charged molecular ions arising in col-lisions of several kiloelectronvolt H+, He2+, and Ar6+ ions with molecules of the simplest alkanes (from methane to butane). Using the method of time-of-flight mass spectrometry, the formation cross sections of dissociation-induced fragment ions are measured. The dissociation takes place when an incident ion captures an electron from a methane, ethane, or propane molecule. The role of additional ionization of the molecule, which accompanies the electron capture by the incident ion, is elucidated. The kinetic energy spectrum for protons resulting from the fragmentation of multiply charged alkane ions is determined. The most plausible kinetic energies of protons depending on the degree of ionization and molecule size fall into the range 1-25 eV. It is shown that, when the molecule loses several electrons, the kinetic energies of protons are governed by Coulomb interaction between all fragment ions and are determined by their flying apart from the relative spatial arrangement of corresponding atoms in a parent molecule.

Afrosimov, V. V.; Baranova, L. A.; Basalaev, A. A.; Panov, M. N.; Smirnov, O. V.; Tulub, A. V.

2010-03-01

83

Exploratory study of coal conversion chemistry. Quarterly report No. 2, August 19, 1981-November 18, 1981. [Hydroxydipnenylmethanes, triphenylmethane, diphenylether  

SciTech Connect

This report describes work accomplished under two tasks: Task A, mechanisms of donor-solvent coal liquefaction, and Task B, CO/H/sub 2/O conversion systems. Under Task A, we describe additional evidence relating to the question of the mechanism of the iron oxide catalyzed cleavage of hydroxydiphenylmethanes. o-Hydroxydiphenylmethane is relatively more sensitive to catalysis by Fe/sub 3/O/sub 4/, a possible one electron oxidant, and triphenylmethane is relatively more sensitive to catalyzed cleavage by SiO/sub 2//Al/sub 2/O/sub 3/, a strong Bronsted acid catalyst. This provides further evidence that in the former case the reactions of radical cations are important in the cleavage mechanism. Tests with Cr/sub 2/O/sub 3/ show it to be ineffective under our reaction conditions as a catalyst for hydroxydiphenylmethane cleavage. We have also used the decomposition of diphenylether in tetralin, which we have previously shown to occur by a radical displacement reaction, as an indicator of steady state radical concentration in tetralin. The results of these experiments indicate that radical concentrations in tetralin are not significantly increased by spiking the tetralin with 1,2-dihydronaphthalene. This in turn suggests that rapid disproportionation of 1,2-dihydronaphthalene to tetralin and naphthalene takes place by way of a concerted reaction, in addition to a slower radical disproportionation process that may provide the steady state radical concentration supported by the equilibrium concentration of 1,2-dihydronaphthalene. Under Task B1, we have found a correlation between initial pH and CO pressure on the conversion of PSOC-26 coal to toluene soluble products. A pH dependence was also observed for PSOC-233 coal, similar to results with PSOC-26. Under Task B2, we have studied anisole as a model oxygen containing structure in coal.

Not Available

1982-01-29

84

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

85

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

86

Exploratory study of coal-conversion chemistry. Quarterly report No. 5, May 19, 1982-August 18, 1982  

SciTech Connect

Initial runs of coal liquefaction products through the automatically switched, multicolumn, solvent-extraction/high-pressure liquid chromatography systems have been performed. This separation was followed by field ionization mass spectrometric analysis of the volatile portions of each of the separated fractions. The separation scheme is described, and results of one of the initial separations are summarized. The FIMS spectrum of one of the fractions (lower molecular weight nitrogen heterocycles) is presented and the types of information available from this less-than-ideal case (i.e., broad HPLC fraction) are discussed in the context of the objective of this subtask. We studied the thermolysis of bibenzyl in D/sub 2/O at 400/sup 0/C. The major products were toluene and stilbene. Minor products were benzene, ethylbenzene, styrene, diphenylmethane, and phenanthrene. The recovered bibenzyl and products contained significant quantities of deuterium. From the degree of deuterium incorporation, a statistical determination for a simple series of consecutive exchange reactions was derived. The reaction scheme involves an initial slow homolysis of the starting bibenzyl to yield benzyl radical, which, in turn, reacts with D/sub 2/O to form OD. OD then rapidly reacts with bibenzyl to yield bibenzyl radical, and the formed bibenzyl radical abstracts deuterium from the medium to form products. The chemistry suggested here demonstrates that water can act as an H-donor because it readily transfers hydrogen to organic free radicals. We further suggest that water can generate hydrogen atoms if CO is present.

Ross, D.S.; McMillen, D.F.; Ogier, W.C.; Fleming, R.H.; Hum, G.P.

1982-10-01

87

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

88

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

89

Use of molecular modeling to design alkane activation catalysts  

SciTech Connect

Efficient alkane-activation catalysts are needed for a number of applications including methane conversion to liquid fuels, clean-up of dilute waste streams, and for oxidation of higher molecular weight alkanes, olefins, and aromatics. For some of these applications, high selectivity and regioselectively of the catalyst is desired. Our work takes a biomimetic approach to the development of shape and size selective catalysts using computer-aided molecular design (CAMD) techniques. The biomimetic CAMD methodology consists of several elements, including: (1) investigation of biological catalysts, especially those like methane monooxygenase and cytochrome P/sub 450/ that activate C-H bonds, to determine the structural features to be designed into a synthetic catalyst, (2) molecular mechanics calculations to evaluate potential catalysts, (3) synthesis of the designed catalyst, (4) spectroscopic characterization of the synthetic catalysts, and (5) catalyst testing for activity and selectivity. The activity tests and structural information provide a basis for making further improvements in the catalyst design. This biomimetic CAMD methodology is being used to design shape and size selective catalysts based on the metalloporphyrins. Designed metalloporphyrins with bulky substituents attached so as to give a small methane-binding cavity at the active metal center have been synthesized and tested. The photochemical production of the co-reductant required in the reaction that mimics cytochrome P/sub 450/ and the synthesis of bis-deep-pocket porphyrins are also described. 51 refs., 8 figs.

Shelnutt, J.A.

1989-07-28

90

The effect of environmental factors on stable isotopic composition of n-alkanes in Mediterranean olive oils  

NASA Astrophysics Data System (ADS)

Traceability of the geographic origin of olive oils is an important issue from both commercial and health perspectives. This study evaluates the impact of environmental factors on stable C and H isotope compositions of n-alkanes in extra virgin olive oils from Croatia, France, Greece, Italy, Morocco, Portugal, Slovenia, and Spain. The data are used to investigate the applicability of stable isotope methodology for olive oil regional classification in the Mediterranean region. Analysis of stable C isotope composition of n-C29 alkane showed that extra virgin olive oils from Portugal and Spain have the most positive n-C29 alkane delta13C values. Conversely, olive oils from Slovenia, northern and central Italy are characterized by the most negative values. Overall, the n-C29 alkane delta13C values show a positive correlation with the mean air temperature during August-December and a negative correlation with the mean relative humidity during these months. Analysis of stable H isotope composition of n-C29 alkane revealed that the deltaD values are the most positive in olive oils from Greece and Morocco and the most negative in oils from northern Italy. The deltaD values of oils show significant correlation with all the analyses geographical parameters: the mean air temperature and relative humidity during August-December, the total amount of rainfall (the same months) and the annual deltaD values of precipitation. As predictor variables in the Categorical Data Analysis, the n-C29 alkane deltaD values show the most significant discriminative power, followed by the n-C29 alkane delta13C values. Overall, 93.4% of olive oil samples have been classified correctly into one of the production regions. Our findings suggest that an integrated analysis of C and H isotope compositions of n-alkanes extracted from extra virgin olive oil could become a useful tool for geographical provenancing of this highly popular food commodity.

Pedentchouk, Nikolai; Mihailova, Alina; Abbado, Dimitri

2014-05-01

91

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

92

Modeling the influence of alkane molecular structure on secondary organic aerosol formation.  

PubMed

Secondary Organic Aerosols (SOA) production and ageing is a multigenerational oxidation process involving the formation of successive organic compounds with higher oxidation degree and lower vapor pressure. Intermediate Volatility Organic Compounds (IVOC) emitted to the atmosphere are expected to be a substantial source of SOA. These emitted IVOC constitute a complex mixture including linear, branched and cyclic alkanes. The explicit gas-phase oxidation mechanisms are here generated for various linear and branched C10-C22 alkanes using the GECKO-A (Generator for Explicit Chemistry and Kinetics of Organics in the Atmosphere) and SOA formation is investigated for various homologous series. Simulation results show that both the size and the branching of the carbon skeleton are dominant factors driving the SOA yield. However, branching appears to be of secondary importance for the particle oxidation state and composition. The effect of alkane molecular structure on SOA yields appears to be consistent with recent laboratory observations. The simulated SOA composition shows, however, an unexpected major contribution from multifunctional organic nitrates. Most SOA contributors simulated for the oxidation of the various homologous series are far too reduced to be categorized as highly oxygenated organic aerosols (OOA). On a carbon basis, the OOA yields never exceeded 10% regardless of carbon chain length, molecular structure or ageing time. This version of the model appears clearly unable to explain a large production of OOA from alkane precursors. PMID:24600999

Aumont, Bernard; Camredon, Marie; Mouchel-Vallon, Camille; La, Stéphanie; Ouzebidour, Farida; Valorso, Richard; Lee-Taylor, Julia; Madronich, Sasha

2013-01-01

93

Identification of alkane hydroxylase genes in Rhodococcus sp. strain TMP2 that degrades a branched alkane  

E-print Network

Abstract Rhodococcus sp. TMP2 is an alkanedegrading strain that can grow with a branched alkane as a sole carbon source. TMP2 degrades considerable amounts of pristane at 20°C but not at 30°C. In order to gain insights into microbial alkane degradation, we characterized one of the key enzymes for alkane degradation. TMP2 contains at least five genes for membrane-bound, non-heme iron, alkane hydroxylase, known as AlkB (alkB1–5). Phylogenetical analysis using bacterial alkB genes indicates that TMP2 is a close relative of the alkane-degrading bacteria, such as Rhodococcus erythropolis NRRL B-16531 and Q15. RT-PCR analysis showed that expressions of the genes for AlkB1 and AlkB2 were apparently induced by the addition of pristane at a low temperature. The results suggest that TMP2 recruits certain alkane hydroxylase systems to utilize a branched alkane under low temperature conditions.

Masaaki Morikawa; D. Takei; K. Washio; M. Morikawa

94

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

95

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

96

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

97

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

98

Sophorolipids from Torulopsis bombicola as microbial surfactants in alkane fermentations  

Microsoft Academic Search

The possible role of sophorolipids from Torulopsis bombicola was investigated in alkane fermentation. Sophorolipids and related model compounds specifically stimulated the growth of strains of Torulopsis yeasts on insoluble alkanes and may act as a specific growth factor. There may be more than one way for a yeast to be stimulated to incorporate alkanes for growth.

Shigeo Inoue; Susumu Ito

1982-01-01

99

In situ detection of anaerobic alkane metabolites in subsurface environments  

PubMed Central

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

100

Chemistry of secondary organic aerosol formation  

NASA Astrophysics Data System (ADS)

The photooxidation of volatile organic compounds (VOCs) in the atmosphere can lead to the formation of secondary organic aerosol (SOA), a major component of fine particulate matter. Improvements to air quality require insight into the many reactive intermediates that lead to SOA formation, of which only a small fraction have been measured at the molecular level. This thesis describes the chemistry of secondary organic aerosol (SOA) formation from several atmospherically relevant hydrocarbon precursors. Photooxidation experiments of methoxyphenol and phenolic compounds and C12 alkanes were conducted in the Caltech Environmental Chamber. These experiments include the first photooxidation studies of these precursors run under sufficiently low NOx levels, such that RO2 + HO2 chemistry dominates, an important chemical regime in the atmosphere. Using online Chemical Ionization Mass Spectrometery (CIMS), key gas-phase intermediates that lead to SOA formation in these systems were identified. With complementary particle-phase analyses, chemical mechanisms elucidating the SOA formation from these compounds are proposed. Three methoxyphenol species (phenol, guaiacol, and syringol) were studied to model potential photooxidation schemes of biomass burning intermediates. SOA yields (ratio of mass of SOA formed to mass of primary organic reacted) exceeding 25% are observed. Aerosol growth is rapid and linear with the organic conversion, consistent with the formation of essentially non-volatile products. Gas and aerosol-phase oxidation products from the guaiacol system show that the chemical mechanism consists of highly oxidized aromatic species in the particle phase. Syringol SOA yields are lower than that of phenol and guaiacol, likely due to unique chemistry dependent on methoxy group position. The photooxidation of several C12 alkanes of varying structure n-dodecane, 2-methylundecane, cyclododecane, and hexylcyclohexane) were run under extended OH exposure to investigate the effect of molecular structure on SOA yields and photochemical aging. Peroxyhemiacetal formation from the reactions of several multifunctional hydroperoxides and aldehyde intermediates was found to be central to organic growth in all systems, and SOA yields increased with cyclic character of the starting hydrocarbon. All of these studies provide direction for future experiments and modeling in order to lessen outstanding discrepancies between predicted and measured SOA.

Yee, Lindsay Diana

101

Light hydrocarbon gas conversion using porphyrin catalysts  

SciTech Connect

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

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

1995-07-01

102

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

103

Phase equilibria of alkanes in natural gas systems. 2: Alkanes in ethane  

Microsoft Academic Search

A previously reported novel chromatographic technique for measuring capacity factors to yield infinite dilution activity coefficients for liquid and solid n-alkanes in compressed gases can be used to estimate solubilities, virial coefficients, partial molar volumes, and partial molar enthalpies at infinite dilution. This paper reports experimental capacity factors and their corresponding solubilities for the n-alkanes from CââHââ to CââHââ in

David Suleiman; Charles A. Eckert

1995-01-01

104

Adsorption characteristics of alkanes onto carbon nanotube bundles: Grand Canonical  

E-print Network

The separation of alkanes is important for a range of applications such as oil refinement, filtration and gas separation. Carbon nanotubes, with their large surface area are highly promising for applications utilising alkane adsorption and separation. Rather than remaining isolated however, nanotubes tend to bundle together, and the adsorption properties of such bundles and subsequent potential for practical alkane separation is not yet entirely clear. For this reason, we have undertaken Grand Canonical Monte Carlo simulations in order to study the adsorption properties of alkanes on nanotube bundles. Our results show how precise control of temperature and pressure allows selective adsorption of certain alkanes, and we describe in detail the reasons behind this.

Monte Carlo Simulation; James Cannon; Thijs J. H. Vlugt; Shigeo Maruyama; Junichiro Shiomi

105

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

106

Interfacial Properties of Semifluorinated Alkane Diblock Copolymers  

NASA Astrophysics Data System (ADS)

The surface interaction of semifluorinated alkane diblock (SFAs) copolymers with water and normal alkanes are studied using explicit atom molecular dynamics (MD) simulations. At the diblock/air interface, the surface is dominated by fluorinated groups as a result of their low surface tension, and these groups reside at the interface for longer periods of time than the hydrogenated groups. Fluorinating even a single end group on an otherwise hydrogenated chain results in low surface tensions, close to that of perfluoroalkanes and far from normal alkanes. For the interface with water, results for the rate of water uptake by alkanes, perfluoroalkanes, and SFAs will be presented. Additionally, we report the interfacial surface tensions and equilibrium density profiles for these samples, focusing on the prevalence of fluorinated and hydrogenated segments at each interface. Sandia is a multiprogram laboratory operated by Sandia Corporation, a Lockheed Martin Company, for the United States Department of Energy's National Nuclear Security Administration under Contract DE-AC04- 94AL85000.

Pierce, Flint; Perahia, Dvora; Tsige, Mesfin; Borodin, Oleg; Grest, Gary

2008-03-01

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

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

109

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

110

Alkane biosynthesis by decarbonylation of aldehydes catalyzed by a particulate preparation from Pisum sativum.  

PubMed Central

Mechanism of enzymatic conversion of a fatty acid to the corresponding alkane by the loss of the carboxyl carbon was investigated with particulate preparations from Pisum sativum. A heavy particulate preparation (sp. gr., 1.30 g/cm3) isolated by two density-gradient centrifugation steps catalyzed conversion of octadecanal to heptadecane and CO. Experiments with [1-3H,1-14C]octadecanal showed the stoichiometry of the reaction and retention of the aldehydic hydrogen in the alkane during this enzymatic decarbonylation. This decarbonylase showed an optimal pH of 7.0 and a Km of 35 microM for the aldehyde. This enzyme was severely inhibited by metal ion chelators and showed no requirement for any cofactors. Microsomal preparations and the particulate fractions from the first density-gradient step catalyzed acyl-CoA reduction to the corresponding aldehyde. Electron microscopic examination showed the presence of fragments of cell wall/cuticle but no vesicles in the decarbonylase preparation. It is concluded that the aldehydes produced by the acyl-CoA reductase located in the endomembranes of the epidermal cells are converted to alkanes by the decarbonylase located in the cell wall/cuticle region. PMID:6593720

Cheesbrough, T M; Kolattukudy, P E

1984-01-01

111

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.

112

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.

113

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

114

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

115

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

116

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

E-print Network

Department of Chemistry & Biochemistry UCLA Chemistry, Biochemistry & Chemistry Material Science ...........................................................................................................................................4 Chemistry & Biochemistry Undergraduate Office..............................................................................................6 Majors in Chemistry & Biochemistry

Levine, Alex J.

117

In Vivo Evolution of Butane Oxidation by Terminal Alkane  

E-print Network

Enzymes of the AlkB and CYP153 families catalyze the first step in the catabolism of medium-chain-length alkanes, selective oxidation of the alkane to the 1-alkanol, and enable their host organisms to utilize alkanes as carbon sources. Small, gaseous alkanes, however, are converted to alkanols by evolutionarily unrelated methane monooxygenases. Propane and butane can be oxidized by CYP enzymes engineered in the laboratory, but these produce predominantly the 2-alkanols. Here we report the in vivo-directed evolution of two mediumchain-length terminal alkane hydroxylases, the integral membrane di-iron enzyme AlkB from Pseudomonas putida GPo1 and the class II-type soluble CYP153A6 from Mycobacterium sp. strain HXN-1500, to enhance their activity on small alkanes. We established a P. putida evolution system that enables selection for terminal alkane hydroxylase activity and used it to select propane- and butane-oxidizing enzymes based on enhanced growth complementation of an adapted P. putida GPo12(pGEc47?B) strain. The resulting enzymes exhibited higher rates of 1-butanol production from butane and maintained their preference for terminal hydroxylation. This in vivo evolution system could be useful for directed evolution of enzymes that function efficiently to hydroxylate small alkanes in engineered hosts. Microbial utilization and degradation of alkanes was discovered almost a century ago (27). Since then, several enzyme

Hydroxylases Alkb; Daniel J. Koch; Mike M. Chen; Jan B. Van Beilen; Frances H. Arnold

2008-01-01

118

Simulating the vapour–liquid equilibria of large cyclic alkanes  

E-print Network

Self-adapting fixed endpoint configurational-bias Monte Carlo simulations in the Gibbs ensemble were carried out to determine the vapour–liquid coexistence curves of cyclic alkanes from c-pentane to c-octadecane. In general, the critical temperatures and densities of the cyclic alkanes are substantially higher than those of their linear counterparts. Furthermore, the simulation data point to a maximum in the critical density for cyclic alkanes with about eight carbon atoms as also observed for the linear alkanes. 1.

Jun-seok Lee; Collin D. Wick; John M. Stubbs; J. Ilja Siepmann

2004-01-01

119

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

120

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

Code of Federal Regulations, 2013 CFR

...2013-07-01 2013-07-01 false Mixture of hydrofluoro alkanes and hydrofluoro...Specific Chemical Substances § 721.4464 Mixture of hydrofluoro alkanes and hydrofluoro...substances identified generically as a mixture of hydrofluoro alkanes and...

2013-07-01

121

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

Code of Federal Regulations, 2012 CFR

...2012-07-01 2012-07-01 false Mixture of hydrofluoro alkanes and hydrofluoro...Specific Chemical Substances § 721.4464 Mixture of hydrofluoro alkanes and hydrofluoro...substances identified generically as a mixture of hydrofluoro alkanes and...

2012-07-01

122

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

Code of Federal Regulations, 2011 CFR

...2011-07-01 2011-07-01 false Mixture of hydrofluoro alkanes and hydrofluoro...Specific Chemical Substances § 721.4464 Mixture of hydrofluoro alkanes and hydrofluoro...substances identified generically as a mixture of hydrofluoro alkanes and...

2011-07-01

123

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

Code of Federal Regulations, 2010 CFR

...2010-07-01 2010-07-01 false Mixture of hydrofluoro alkanes and hydrofluoro...Specific Chemical Substances § 721.4464 Mixture of hydrofluoro alkanes and hydrofluoro...substances identified generically as a mixture of hydrofluoro alkanes and...

2010-07-01

124

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

125

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

126

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

127

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

128

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

129

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...721.10148 Acryloxy alkanoic alkane derivative with mixed metal oxides (generic...generically as acryloxy alkanoic alkane derivative with mixed metal oxides (PMN...

2010-07-01

130

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...721.10148 Acryloxy alkanoic alkane derivative with mixed metal oxides (generic...generically as acryloxy alkanoic alkane derivative with mixed metal oxides (PMN...

2013-07-01

131

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...721.10148 Acryloxy alkanoic alkane derivative with mixed metal oxides (generic...generically as acryloxy alkanoic alkane derivative with mixed metal oxides (PMN...

2011-07-01

132

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...721.10148 Acryloxy alkanoic alkane derivative with mixed metal oxides (generic...generically as acryloxy alkanoic alkane derivative with mixed metal oxides (PMN...

2012-07-01

133

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

134

Understanding the anomalous alkane selectivity of ZIF-7 in the separation of light alkane/alkene mixtures.  

PubMed

C2 and C3 alkanes are selectively adsorbed from mixtures over the corresponding alkenes on the zeolite imidazolate framework ZIF-7 through a gate-opening mechanism. As a result, the direct production of the pure alkene upon adsorption and the pure alkane upon desorption in packed columns is possible. Herein, a detailed investigation of the step-wise adsorption and separation of alkanes and alkenes is presented, together with a rigorous performance assessment. A molecular picture of the gate-opening mechanism underlying the unprecedented selectivity towards alkane adsorption is proposed based on DFT calculations and a thermodynamic analysis of the adsorption-desorption isotherms. PMID:21755546

van den Bergh, Johan; Gücüyener, Canan; Pidko, Evgeny A; Hensen, Emiel J M; Gascon, Jorge; Kapteijn, Freek

2011-08-01

135

Infrared spectra and structure of perfluoro-n-alkanes isolated in n-alkane matrices prepared by vapor deposition  

SciTech Connect

In this paper, low-temperature vapor deposition is used to make amorphous films of perfluoro-n-alkanes diluted in n-alkane matrices. Annealing these films leads to narrow infrared bands due to reduced intermolecular interaction between the perfluoro-n-alkane chains. Many intense bands in the 1100-1300 cm{sup -1} range, varying with chain length, are observed and assigned based on a simple coupled oscillator model. Isolated perfluoro-n-alkane chains are helical and highly ordered. 27 refs., 10 figs., 2 tabs.

Cho, H.G.; Strauss, H.L.; Snyder, R.G. [Univ. of California, Berkeley, CA (United States)

1992-06-25

136

Pulse radiolysis studies on liquid alkanes and related polymers  

NASA Astrophysics Data System (ADS)

Absorption spectra of alkane radical cations, alkane excited states, and alkyl radicals and electrons in irradiated neat liquid alkanes at room temperature were assigned on subnanosecond and nanosecond time scale after an electron pulse. Two broad visible and near-infrared absorption bands of alkane excited states and radical cations, and UV absorption band of alkyl radicals were observed in neat n-alkanes. In neat cyclohexane and trans-decalin, very broad visible absorption band mainly due to alkane excited states and UV absorption band of alkyl radicals were observed. In neat neopentane and isooctane, visible absorption bands were not observed, although UV absorption bands of alkyl radicals were observed. The wavelengths of absorptive peaks of alkane radical cations and excited states become longer with increasing the number of carbon atoms of n-alkanes. The lifetimes of alkane radical cations become shorter with decreasing the number of carbon atoms of n-alkanes and are shorter than those of electrons in neat alkanes. The main processes of the alkyl radical formation finish within the time resolution of our system (about 20 ps). The alkyl radicals are produced mainly from excited radicals cations and partly from higher excited states, the lowest excited states, radical cations, and thermal hydrogen atoms. In irradiated ethylene-propylene copolymers, broad absorption bands of excited states and tail parts of absorption bands of radical cations and electrons were observed in visible and near-infrared region, although UV absorption of alkyl radicals was not confirmed lack of transparency of polymer films.

Tagawa, S.; Hayashi, N.; Yoshida, Y.; Washio, M.; Tabata, Y.

137

Activation of Alkanes with Organotransition Metal Complexes  

NASA Astrophysics Data System (ADS)

Alkanes, although plentiful enough to be considered for use as feedstocks in large-scale chemical processes, are so unreactive that relatively few chemical reagents have been developed to convert them to molecules having useful functional groups. However, a recently synthesized iridium (lr) complex successfully converts alkanes into hydridoalkylmetal complexes (M + R-H --> R-M-H). This is a dihydride having the formula Cp*(L)IrH2, where Cp* and L are abbreviations for the ligands (CH3)5C5 and (CH3)3P, respectively. Irradiation with ultraviolet light causes the dihydride to lose H2, generating the reactive intermediate Cp*IrL. This intermediate reacts rapidly with C-H bonds in every molecule so far tested (including alkanes) and leads to hydridoalkyliridium complexes Cp*(L)Ir(R)(H). Evidence has been obtained that this C-H insertion, or oxidative addition, reaction proceeds through a simple three-center transition state and does not involve organic free radicals as intermediates. Thus the intermediate Cp*IrL reacts most rapidly with C-H bonds having relatively high bond energies, such as those at primary carbon centers, in small organic rings, and in aromatic rings. This contrasts directly with the type of hydrogen-abstraction selectivity that is characteristic of organic radicals. The hydridoalkyliridium products of the insertion reactions can be converted into functionalized organic molecules--alkyl halides--by treatment with mercuric chloride followed by halogens. Expulsion (reductive elimination) of the hydrocarbon from the hydridoalkyliridium complexes can be induced by Lewis acids or heat, regenerating the reactive intermediate Cp*IrL. Oxidative addition of the corresponding rhodium complexes Cp*RhL to alkane C-H bonds has also been observed, although the products formed in this case are much less stable and undergo reductive elimination at -20 degrees C. These and other recent observations provide an incentive for reexamining the factors that have been assumed to control the rate of reaction of transition metal complexes with C-H bonds--notably the need for electron-rich metals and the proximity of reacting centers.

Bergman, Robert G.

1984-03-01

138

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

139

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

140

A Toolkit to Enable Hydrocarbon Conversion in Aqueous Environments  

PubMed Central

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

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

2012-01-01

141

Spectroscopy of the tilde A state of NO-alkane complexes (alkane = methane, ethane, propane, and n-butane)  

NASA Astrophysics Data System (ADS)

We have recorded (1+1) resonance-enhanced multiphoton ionization spectra of complexes formed between NO and the alkanes: CH4, C2H6, C3H8, and n-C4H10. The spectra correspond to the tilde A ? tilde X transition, which is a NO-localized 3s ? 2p?* transition. In line with previous work, the spectrum for NO-CH4 has well-defined structure, but this is only partially resolved for the other complexes. The spectra recorded in the NO+-alkane mass channels all show a slowly rising onset, followed by a sharp offset, which is associated with dissociation of NO-alkane, from which binding energies in the tilde X and tilde A states are deduced. Beyond this sharp offset, there is a further rise in signal, which is attributed to fragmentation of higher complexes, NO-(alkane)n. Analysis of these features allows binding energies for (NO-alkane) ... alkane to be estimated, and these suggest that in the NO-(alkane)2 complexes, the second alkane molecule is bound to the first, rather than to NO. Calculated structures for the 1:1 complexes are reported, as well as binding energies.

Tamé-Reyes, Victor M.; Gardner, Adrian M.; Harris, Joe P.; McDaniel, Jodie; Wright, Timothy G.

2012-12-01

142

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

143

Superacid catalyzed coal conversion chemistry. 1st and 2nd quarterly technical progress reports, September 1, 1983-March 30, 1984. [Model compound consisting of 2 benzene rings connected with various bridging units such as alkylidene, ether, sulfide, etc  

SciTech Connect

In our laboratories we have previously developed a mild coal conversion process. This involves the use of a superacid system consisting of HF and BF/sub 3/ in presence of hydrogen and/or a hydrogen donor solvent. In order to understand the chemistry involved in the process of depolymerization of coal by the HF:BF/sub 3/:H/sub 2/ system we are carrying out a systematic study of a number of coal model compounds. The model compounds selected for present study have two benzene rings connected with various bridging units such as alkylidene, ether, sulfide etc. From studies so far carried out it appears that high pyridine extractibilities achieved by treating coal at temperature below 100/sup 0/C results from the cleavage of bridges such as present in bibenzyl, diphenyl methane, dibenzyl ether, dibenzyl sulfide etc. On the other hand the increased cyclohexane extractibility and distillability observed at relatively higher temperatures and hydrogen pressures reflects the hydrogenation and cleavage of the aromatic backbone in coal structure similar to what is seen in the conversion of model compounds such as biphenyl, diphenyl ether, diphenyl sulfide, anthracene, etc.

Olah, G.A.

1984-01-01

144

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

145

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: 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, separation processes, organic and physical chemistry, novel materials, and advanced methods of analysis.

Cairns, E. J.

1994-06-01

146

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

147

The heterogeneous partial oxidation of light alkanes  

E-print Network

(cont.) With this approach, an upper bound on the yield for OCM was computed. Results showed that even with optimal surface chemistry, strict limits existed on the attainable yield. Surface energetics necessary for superior ...

Su, Yee San, 1977-

2004-01-01

148

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

149

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

150

The vapour - liquid equilibrium of n-alkanes  

NASA Astrophysics Data System (ADS)

The vapour - liquid equilibrium of short n-alkanes is considered by using perturbation theory. This requires as a previous step obtaining an equation of state (EOS) for hard flexible models. An EOS for hard-n-alkane models which shows excellent agreement with computer simulation of hard-n-alkane models with up to 100 carbon atoms is proposed. This EOS is combined with a mean-field term and the vapour - liquid equilibrium of n-alkanes is computed. When theoretical critical densities and pressures are plotted as a function of the number of carbon atoms, a maximum is found. This is in agreement with experiment. The conditions for the appearance of such a maximum in general chain models are established. Some ways of improving the mean-field theory are suggested.

Vega, C.; Garzon, B.; MacDowell, L. G.; Padilla, P.; Calero, S.; Lago, S.

1996-11-01

151

Development of many-body polarizable force fields for Li-battery components: 1. Ether, alkane, and carbonate-based solvents.  

PubMed

Classical many-body polarizable force fields were developed for n-alkanes, perflouroalkanes, polyethers, ketones, and linear and cyclic carbonates on the basis of quantum chemistry dimer energies of model compounds and empirical thermodynamic liquid-state properties. The dependence of the electron correlation contribution to the dimer binding energy on basis-set size and level of theory was investigated as a function of molecular separation for a number of alkane, ether, and ketone dimers. Molecular dynamics (MD) simulations of the force fields accurately predicted structural, dynamic, and transport properties of liquids and unentangled polymer melts. On average, gas-phase dimer binding energies predicted with the force field were between those from MP2/aug-cc-pvDz and MP2/aug-cc-pvTz quantum chemistry calculations. PMID:16553446

Borodin, Oleg; Smith, Grant D

2006-03-30

152

DFT derived solvation models for organic compounds in alkane solvents  

NASA Astrophysics Data System (ADS)

From a density functional theory (DFT) analysis of solvation and the different components which comprise the free energy of solvation we propose quantitative structure-property relationship (QSPR) models to predict free energy of solvation, ?GS0, of organic compounds in seven alkane solvents ( n-pentane, n-hexane, n-heptane, n-octane, n-nonane, n-decane, and n-hexadecane). The data contains 151 structurally different compounds containing diverse organic functions: unbranched and branched alkanes, cycloalkanes, aromatics, alcohols, aldehydes, ketones, esters, ethers, amines, nitriles, pyridines, fluorinated hydrocarbons, thiols, sulfides, carboxylic acids and nitro hydrocarbons; covering a ?GS0 range from about -50 to 0 kJ/mol. The models for the seven n-alkane solvents contain the same two molecular descriptors, one DFT descriptor (softness) and one geometric (molecular surface area). This fact suggests that the physical mechanisms behind the solvation of organic compounds in n-alkane solvents are of the same nature, as expected from the similar physical and chemical properties of alkanes. The models proposed have the merit of predicting free energy of solvation in alkane solvents with fewer descriptors than other QSPR models reported in the literature having similar statistics, allowing in this way a well-defined physical interpretation. The two descriptors have definite physical meaning corresponding to the different components which comprise free energy of solvation. Thus, the models proposed reach the desired compromise among simpleness, physical interpretation and computation time.

Delgado, Eduardo J.; Alderete, Joel B.; Jaña, Gonzalo A.

2006-06-01

153

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

154

A Comparison of the Monolayer Dynamics of the Branched Alkane Squalane and the Normal Alkane Tetracosane Adsorbed on Graphite  

NASA Astrophysics Data System (ADS)

Squalane is a branched alkane (C_30H_62) with 24 carbon atoms in its backbone, like the normal alkane tetracosane ( n-C_24H_50), and six symmetrically placed methyl side groups. In general, branched alkanes such as squalane are better lubricants than n-alkanes. We have studied the dynamics of the squalane and tetracosane monolayers by quasielastic neutron scattering and molecular dynamics (MD) simulations on two different time scales. Both experiments and simulations showed that diffusion at 260 K is about 2.5 times faster in the squalane than in the tetracosane system. It is somewhat surprising that the diffusion in a system with a branched alkane is faster than with a normal alkane. A possible explanation is that the squalane molecule does not bind as strongly to the surface as tetracosane, because the MD simulations have shown that the adsorbed molecules have a distorted backbone. This may also explain why the slow intramolecular motions associated with conformational changes are seen at lower temperatures in the squalane than the tetracosane monolayer where they are only observed near melting.

Enevoldsen, A. D.; Hansen, F. Y.; Diama, A.; Taub, H.

2004-03-01

155

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

156

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

157

One-step hydrotreatment of vegetable oil to produce high quality diesel-range alkanes.  

PubMed

A one-step hydrotreatment of vegetable oil combining deoxygenation and isomerization to directly produce low cloud point, high quality diesel is devised. The Pt/zeolite bifunctional catalysts prepared by using SAPO-11 and ZSM-22 zeolites as supports are used in this process. Catalytic reactions are conducted in a fixed-bed reactor under a hydrogen atmosphere. Over the bifunctional catalyst, 100 % conversion of soybean oil is obtained at 357 °C, 4 MPa, and 1 h(-1), and 80 % organic liquid yield is achieved, which is close to the maximum theoretical liquid yield. In the organic products, the alkanes selectivity is 100 % with an i-alkanes selectivity above 63 %. NH(3)-temperature programmed desorption (TPD), pyridine IR spectroscopy, and other characterization techniques are used to study the effect of the support acidity on the reaction pathway. Over the Pt/zeolite bifunctional catalyst with less strong Lewis acid sites, the reaction proceeds via the decarboxylation plus decarbonylation pathway. This one-step method provides a new strategy to produce low cloud point, high quality diesel from biomass feedstock in a more economic and attractive way. PMID:22764086

Wang, Congxin; Tian, Zhijian; Wang, Lei; Xu, Renshun; Liu, Qianhe; Qu, Wei; Ma, Huaijun; Wang, Bingchun

2012-10-01

158

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

159

Conversion Contraption  

NSDL National Science Digital Library

It's show time for eighth grade physical science students after a week of designing, building, and refining Conversion Contraptions. The contraptions are fun combinations of moving parts that use many forms of energy and many conversions of energy. It's t

Chahrour, Janet

2000-09-01

160

Alkane inducible proteins in Geobacillus thermoleovorans B23  

PubMed Central

Background Initial step of ?-oxidation is catalyzed by acyl-CoA dehydrogenase in prokaryotes and mitochondria, while acyl-CoA oxidase primarily functions in the peroxisomes of eukaryotes. Oxidase reaction accompanies emission of toxic by-product reactive oxygen molecules including superoxide anion, and superoxide dismutase and catalase activities are essential to detoxify them in the peroxisomes. Although there is an argument about whether primitive life was born and evolved under high temperature conditions, thermophilic archaea apparently share living systems with both bacteria and eukaryotes. We hypothesized that alkane degradation pathways in thermophilic microorganisms could be premature and useful to understand their evolution. Results An extremely thermophilic and alkane degrading Geobacillus thermoleovorans B23 was previously isolated from a deep subsurface oil reservoir in Japan. In the present study, we identified novel membrane proteins (P16, P21) and superoxide dismutase (P24) whose production levels were significantly increased upon alkane degradation. Unlike other bacteria acyl-CoA oxidase and catalase activities were also increased in strain B23 by addition of alkane. Conclusion We first suggested that peroxisomal ?-oxidation system exists in bacteria. This eukaryotic-type alkane degradation pathway in thermophilic bacterial cells might be a vestige of primitive living cell systems that had evolved into eukaryotes. PMID:19320977

2009-01-01

161

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

162

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

163

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.

164

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....

165

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

166

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.

167

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

168

Integrated two-liquid phase bioconversion and product-recovery processes for the oxidation of alkanes: Process design and economic evaluation  

SciTech Connect

Pseudomonas oleovorans and recombinant strains containing the alkane oxidation genes can product alkane oxidation genes can produce alkane oxidation products in two-liquid phase bioreactor systems. In these bioprocesses the cells, which grow in the aqueous phase, oxidize apolar, non-water soluble substrates. The apolar products typically accumulate in the emulsified apolar phase. The authors have studied both the bioconversion systems and several downstream processing systems to separate and purify alkanols from these two-liquid phase media. Based on the information generated in these studies, the authors have now designed bioconversion and downstream processing systems for the production of 1-alkanols from n-alkanes on a 10 kiloton/yr scale, taking the conversion of n-octane to 1-octanol as a model system. Here, the authors describe overall designs of fed-batch and continuous-fermentation processes for the oxidation of octane to 1-octanol by Pseudomonas oleovoran, and the authors discuss the economics of these processes. The overall performance of each of these two systems has been modeled with Aspen software. Although the continuous process is about 10% more expensive than the fed-batch process, improvements to reduce overall cost can be achieved more easily for continuous than for fed-batch fermentation by decreasing the dilution rate while maintaining near constant productivity. Improvements relevant to both processes can be achieved by increasing the biocatalyst performance, which results in improved overall efficiency, decreased capital investment, and hence, decreased production cost.

Mathys, R.G.; Schmid, A.; Witholt, B.

1999-08-20

169

A Nonequilibrium Molecular Dynamics Study of the Rheology of Alkanes  

E-print Network

We examine the rheological properties of four different alkanes - n-decane (C 10 H 22 ), n-hexadecane (C 16 H 34 ), n-tetracosane (C 24 H 50 ) and squalane (C 30 H 62 ). The 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. The number of interaction sites ranges from 1000 - 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.

Gupta Cui; S. A. Gupta; S. T. Cui; P. T. Cummings; H. D. Cochran

1996-01-01

170

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

171

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

172

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

173

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

174

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.

175

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.

176

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

177

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

178

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

179

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.

180

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.

181

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

182

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

183

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

184

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

185

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.

186

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

187

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

188

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.

189

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

190

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

E-print Network

Leaf-wax n-alkanes record the plant­water environment at leaf ush Brett J. Tipple1 , Melissa A, UT, and approved December 26, 2012 (received for review August 13, 2012) Leaf-wax n-alkanes 2 H/1 H- ship between n-alkanes 2 H values and climate is appreciated, the quantitative details of the proxy

Tipple, Brett

191

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

192

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

193

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

194

Energy conversion and storage program  

NASA Astrophysics Data System (ADS)

The Energy Conversion and Storage Program applies chemical and chemical engineering 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 storage; (4) characterization of complex chemical processes; and (5) the application of novel materials for energy conversion and transmission. Projects focus on transport-process principles, chemical kinetics, thermodynamics, separation processes, organic and physical chemistry, and advanced methods of analysis. The following five areas are discussed: electrochemical energy storage and conversion; microstructured materials; biotechnology; fossil fuels; and high temperature superconducting processing. Papers have been processed separately for inclusion on the data base.

1990-12-01

195

Dehydrogenation of Light Alkanes over Zeolites  

Microsoft Academic Search

The conversion of light paraffins to olefins and the secondary reactions of the unsaturated compounds were investigated on H-ZSM5 and H-Y zeolites between 733 and 823 K. Steady state- and transient response-isotope tracing studies revealed that two mechanisms of dehydrogenation are operative. The main pathway is represented by monomolecular, protolytic dehydrogenation. This reaction contributes most to steady state olefin production.

Thomas F. Narbeshuber; Axel Brait; Kulathuyier Seshan; Johannes A. Lercher

1997-01-01

196

The kinetic isotope effect for alkane dehydrocyclization  

Microsoft Academic Search

The dehydrocyclization of a mixture of n-octane-d18 and n-octane-d0 are consistent with a mechanism that includes irreversible adsorption of the n-octane and a rate limiting step that involves a kinetic isotope effect of 3.5 ± 0.4 at 482°C. In a competitive conversion of methylcyclohexane and n-octane, where one reactant is the perdeutero isotopomer, the kinetic isotope effect for n-octane is

Buchang Shi; Burtron H. Davis

1996-01-01

197

Some remarks on the solubility of gases in liquid long-chain n -alkanes and n -alkan-1-ols  

Microsoft Academic Search

The Ostwald coefficients L2,1 of He, Ne, Ar, Kr, Xe, N2, O2, CH4 CF4 and SF6 dissolved in several homologousn-alkanes,n-C1H21+2, 6?l?16, andn-alkan-1-ols,n-C1H21+1OH, 1?l?11, were recently measured at 298.15 K and atmospheric pressure with a modified Ben-Naim\\/Baer apparatus. Altogether, 201 gas\\/liquid systems were investigated. For about half of these systems, both pressure control and measurement of the volume of gas dissolved

Emmerich Wilhelm

1997-01-01

198

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

199

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 ...

200

Chemistry Notes  

ERIC Educational Resources Information Center

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

School Science Review, 1976

1976-01-01

201

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

202

Chemistry Notes  

ERIC Educational Resources Information Center

Thirteen ideas are presented that may be of use to chemistry teachers. Topics covered include vitamin C, industrial chemistry, electrical conductivity, electrolysis, alkali metals, vibration modes infra-red, dynamic equilibrium, and some new demonstrations in gaseous combinations. (PS)

School Science Review, 1972

1972-01-01

203

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

204

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

205

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

206

Highly Regioselective Amination of Unactivated Alkanes by Hypervalent  

E-print Network

Dissociation Energies (kcal/mol) Selectivity related to C-H bond dissociation Energy. #12;Axial / Equatrial effects 9 #12;The effect of HFIP (HexaFluoroIsoPropanol) 10 Pseudo-first-order rate constants kobsd were Observed rate constants kobs the concentration of alkane. The slope afforded the second

Katsumoto, Shingo

207

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

208

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

209

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

210

Reaction chemistry of cerium  

SciTech Connect

It is truly ironic that a synthetic organic chemist likely has far greater knowledge of the reaction chemistry of cerium(IV) than an inorganic colleague. Cerium(IV) reagents have long since been employed as oxidants in effecting a wide variety of organic transformations. Conversely, prior to the late 1980s, the number of well characterized cerium(IV) complexes did not extend past a handful of known species. Though in many other areas, interest in the molecular chemistry of the 4f-elements has undergone an explosive growth over the last twenty years, the chemistry of cerium(IV) has for the most part been overlooked. This report describes reactions of cerium complexes and structure.

NONE

1997-01-01

211

Chemistry Links  

NSDL National Science Digital Library

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

Charnine, Michael

2011-04-01

212

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

213

Reconstitution of plant alkane biosynthesis in yeast demonstrates that Arabidopsis ECERIFERUM1 and ECERIFERUM3 are core components of a very-long-chain alkane synthesis complex.  

PubMed

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

2012-07-01

214

Crystallization features of normal alkanes in confined geometry.  

PubMed

How polymers crystallize can greatly affect their thermal and mechanical properties, which influence the practical applications of these materials. Polymeric materials, such as block copolymers, graft polymers, and polymer blends, have complex molecular structures. Due to the multiple hierarchical structures and different size domains in polymer systems, confined hard environments for polymer crystallization exist widely in these materials. The confined geometry is closely related to both the phase metastability and lifetime of polymer. This affects the phase miscibility, microphase separation, and crystallization behaviors and determines both the performance of polymer materials and how easily these materials can be processed. Furthermore, the size effect of metastable states needs to be clarified in polymers. However, scientists find it difficult to propose a quantitative formula to describe the transition dynamics of metastable states in these complex systems. Normal alkanes [CnH2n+2, n-alkanes], especially linear saturated hydrocarbons, can provide a well-defined model system for studying the complex crystallization behaviors of polymer materials, surfactants, and lipids. Therefore, a deeper investigation of normal alkane phase behavior in confinement will help scientists to understand the crystalline phase transition and ultimate properties of many polymeric materials, especially polyolefins. In this Account, we provide an in-depth look at the research concerning the confined crystallization behavior of n-alkanes and binary mixtures in microcapsules by our laboratory and others. Since 2006, our group has developed a technique for synthesizing nearly monodispersed n-alkane containing microcapsules with controllable size and surface porous morphology. We applied an in situ polymerization method, using melamine-formaldehyde resin as shell material and nonionic surfactants as emulsifiers. The solid shell of microcapsules can provide a stable three-dimensional (3-D) confining environment. We have studied multiple parameters of these microencapsulated n-alkanes, including surface freezing, metastability of the rotator phase, and the phase separation behaviors of n-alkane mixtures using differential scanning calorimetry (DSC), temperature-dependent X-ray diffraction (XRD), and variable-temperature solid-state nuclear magnetic resonance (NMR). Our investigations revealed new direct evidence for the existence of surface freezing in microencapsulated n-alkanes. By examining the differences among chain packing and nucleation kinetics between bulk alkane solid solutions and their microencapsulated counterparts, we also discovered a mechanism responsible for the formation of a new metastable bulk phase. In addition, we found that confinement suppresses lamellar ordering and longitudinal diffusion, which play an important role in stabilizing the binary n-alkane solid solution in microcapsules. Our work also provided new insights into the phase separation of other mixed system, such as waxes, lipids, and polymer blends in confined geometry. These works provide a profound understanding of the relationship between molecular structure and material properties in the context of crystallization and therefore advance our ability to improve applications incorporating polymeric and molecular materials. PMID:23947401

Su, Yunlan; Liu, Guoming; Xie, Baoquan; Fu, Dongsheng; Wang, Dujin

2014-01-21

215

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).

216

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

217

Visualizing Conversation  

Microsoft Academic Search

Although the archive of text generated by a persistent conversation (i.e. newsgroup, mailing list, recorded chat, etc.) is searchable, it is not very expressive of the underly- ing social patterns. In this paper we will discuss the design of graphical interfaces that reveal the social structure of the conversation by visualizing patterns such as bursts of activity, the arrival of

Judith S. Donath; Karrie Karahalios; Fernanda B. Viégas

1999-01-01

218

Contentious Conversations  

ERIC Educational Resources Information Center

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

Zuidema, Leah A.

2011-01-01

219

Strategic Conversations  

ERIC Educational Resources Information Center

Strategic conversations are a series of targeted, individualized interactions with teachers that are designed to help them significantly improve their instruction. Unlike typical supervisory feedback, strategic conversations move in two directions. Together, the leader and the teacher identify problems and develop solutions to instructional…

Jackson, Robyn R.

2009-01-01

220

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

221

CLUSTER CHEMISTRY  

SciTech Connect

Metal cluster chemistry is one of the most rapidly developing areas of inorganic and organometallic chemistry. Prior to 1960 only a few metal clusters were well characterized. However, shortly after the early development of boron cluster chemistry, the field of metal cluster chemistry began to grow at a very rapid rate and a structural and a qualitative theoretical understanding of clusters came quickly. Analyzed here is the chemistry and the general significance of clusters with particular emphasis on the cluster research within my group. The importance of coordinately unsaturated, very reactive metal clusters is the major subject of discussion.

Muetterties, Earl L.

1980-05-01

222

Adopting SI Units in Introductory Chemistry.  

ERIC Educational Resources Information Center

Discusses advantages to the use of SI units in dealing with proportionality problems, with particular emphasis on stoichiometric relationships. A table lists conversion relationships commonly used in chemistry, and a single-step "roadmap" is provided for each relationship. (CS)

Davies, William G.; Moore, John W.

1980-01-01

223

Computational Chemistry for Chemistry Educators  

NSDL National Science Digital Library

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

Institute, Shodor C.

224

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

225

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

226

for Undergraduate CHEMISTRY MAJORS  

E-print Network

Technology, Colloid and Surface Chemistry, Consumer Products, Food and Flavor Chemistry, Forensic ChemistryHANDBOOK for Undergraduate CHEMISTRY MAJORS DEPARTMENT OF CHEMISTRY Fall 2010 #12;#12;TABLE OF CONTENTS A Career in Chemistry - What It Means ___________________________________________ 4 What do

Stuart, Steven J.

227

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.

2011-06-01

228

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

229

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

230

Adsorption Kinetics of Alkanes on Purified HiPco Nanotubes  

NASA Astrophysics Data System (ADS)

We present results for the adsorption kinetics of methane, ethane and butane on purified HiPco SWNTs. We studied the adsorption kinetics by monitoring the evolution of the gas pressure with time from the instant at which a dose of adsorbate is added to the sample, until the moment at which equilibrium is reached. The waiting times for comparable coverages increase with increasing alkane chain length. For methane and ethane, the equilibration time decreases with increasing fractional coverage. For the butane, on the other hand, the kinetic measurements display a reverse trend: the equilibration times increase with increasing fractional coverage. We speculate that this observed increase in the waiting time is due to a possible reorientation of adsorbed molecules in the film. The observed differences in adsorption kinetics suggest the possibility of using adsorption as a means to achieve the separation of gaseous alkane mixtures.

Rawat, Dinesh; Bulut, Murat; Migone, Aldo

2008-03-01

231

n-alkane profile of Argemone mexicana leaves.  

PubMed

An n-hexane extract of fresh, mature leaves of Argemone mexicana (Papaveraceae), containing thin-layer epicuticular waxes, has been analysed for the first time by TLC, IR and GLC using standard hydrocarbons. Seventeen long-chain alkanes (n-C18 to n-C34) were identified and quantified. Nonacosane (n-C29) was established as the n-alkane with the highest amount, whilst octadecane (n-C19) was the least abundant component of the extracted wax fraction. The carbon preference index (CPI) calculated for the hydrocarbon sample with the chain lengths between C18 and C34 was 1.2469, showing an odd to even carbon number predominance. PMID:21138052

Bhattacharjee, Indranil; Ghosh, Anupam; Chowdhury, Nandita; Chatterjee, Soroj Kumar; Chandra, Goutam; Laskar, Subrata

2010-01-01

232

Melting of thin films of alkanes on magnesium oxide  

Microsoft Academic Search

Recent incoherent neutron scattering investigations of the dynamics of thin \\u000a alkane films adsorbed on the Magnesium Oxide (100) surface are reported. \\u000a There are marked differences in the behaviour of these films, as a function \\u000a of temperature and coverage, compared to similar measurements on graphite. \\u000a In particular, it has previously been shown that adsorbed multilayer films \\u000a on graphite exhibit an interfacial

T. Arnold; A. Barbour; S. Chanaa; R. E. Cook; D. Fernandez-Canato; P. Landry; T. Seydel; P. Yaron; J. Z. Larese

2009-01-01

233

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

234

Iso-branched semifluorinated alkanes in Langmuir monolayers  

Microsoft Academic Search

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.

M. Broniatowski; P. Dynarowicz-??tka

2006-01-01

235

Molecular evaporation and condensation of liquid n-alkane films  

Microsoft Academic Search

Energetic, structural, and dynamical properties of solid-to-liquid and liquid-to-vapor interfaces and molecular evaporation and condensation processes from high-temperature liquid n-C6H14 and n-C16H34 films were investigated with molecular dynamics simulations. For hexadecane all evaporation events occurred via monomers while for hexane, evaporation of monomers as well as dimers were observed. For both alkane liquids the molecular evaporation mechanism is found to

Ting Kang Xia; Uzi Landman

1994-01-01

236

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

237

Semifluorinated Alkanes as Stabilizing Agents of Fluorocarbon Emulsions  

Microsoft Academic Search

We obtained highly stable, small-sized, and narrowly dispersed perfluorooctyl bromide (PFOB) emulsions using combinations of phospholipids and semifluorinated alkanes CnF2n+1CmH2m+1 (FnHm diblocks) as the emulsifying system. For example, after 6 months at 25°C the average droplet diameter of an emulsion stabilized by F6H10 was only ?80nm, compared to ?180 nm for the reference emulsion stabilized by phospholipids alone. In parallel,

Sabina Marie Bertilla; Pascal Marie; Marie Pierre Krafft

238

Monolayer solids of short (perfluoro)alkanes on graphite  

NASA Astrophysics Data System (ADS)

Calculations are reported for the relative stability of monolayer solid latices on graphite for C2H6, C3H8, C2F6, and C3F8. Triangular, centered rectangular and two-sublattice herringbone lattices are treated. The calculations use all-atom (AA) models and are based on non-bonding interactions formulated for three dimensional dense phases of alkanes and perfluoroalkanes.

Bruch, L. W.

2009-03-01

239

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

Klahn, Stephan; Baumgartner, Desiree; Pfreundt, Ulrike; Voigt, Karsten; Schon, Verena; Steglich, Claudia; Hess, Wolfgang R.

2014-01-01

240

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

241

Energy Conversion and Storage Program  

NASA Astrophysics Data System (ADS)

This report is the 1992 annual progress report for the Energy Conversion and Storage Program, a part of the Energy and Environment Division of the Lawrence Berkeley Laboratory. Work described falls into three broad areas: electrochemistry; chemical applications; and materials applications. The Energy Conversion and Storage Program applies principles of chemistry and materials science to solve problems in several areas: (1) production of new synthetic fuels, (2) development of high-performance rechargeable batteries and fuel cells, (3) development of advanced thermochemical processes for energy conversion, (4) characterization of complex chemical processes and chemical species, and (5) study and application of novel materials for energy conversion and transmission. Projects focus on transport-process principles, chemical kinetics, thermodynamics, separation processes, organic and physical chemistry, novel materials, and advanced methods of analysis. Electrochemistry research aims to develop advanced power systems for electric vehicle and stationary energy storage applications. Chemical applications research includes topics such as separations, catalysis, fuels, and chemical analyses. Included in this program area are projects to develop improved, energy-efficient methods for processing product and waste streams from synfuel plants, coal gasifiers, and biomass conversion processes. Materials applications research includes evaluation of the properties of advanced materials, as well as development of novel preparation techniques. For example, techniques such as sputtering, laser ablation, and poised laser deposition are being used to produce high-temperature superconducting films.

Cairns, E. J.

1993-06-01

242

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

243

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.

244

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

245

Systematic study of aggregation structure and thermal behavior of a series of unique H-shape alkane molecules.  

PubMed

The H-shape alkanes of various arm lengths have been synthesized successfully through the Grignard reaction. The detailed investigation of these novel compounds may allow us to widen the topological chemistry field furthermore. The molecular form and molecular packing structure in the crystal lattice have been revealed successfully on the basis of X-ray structure analysis as well as the analysis of Raman longitudinal acoustic modes (LAM) sensitive to the alkyl zigzag chain segments. The molecular conformation in the crystal lattice is deformed markedly from the originally imagined H-shape. In the cases of C3HOH to C6HOH, for example, the molecules are packed in a complicated manner and the OH···O hydrogen bonds govern the whole intermolecular interactions mainly. Since the alkyl segmental length is not very long, the conformational change is not very drastic, i.e., the small configurational entropy. Synergic effect of the hydrogen bonds and the small configurational entropy gives the higher melting point as known from the thermal data. On the other hand, in the cases of C10HOH and C12HOH, one of the long alkyl chain arms is found to be bent by 90° so that all of the alky chain segments of planar-zigzag conformation can be packed as closely as possible, and the intermolecular OH···O hydrogen bonds are also formed effectively without any mistake. As a result, the contribution of nonbonded intra- and intermolecular van der Waals interactions between the trans-zigzag alkyl chain segments become major, and the coupling of this enthalpy effect with the larger configurational entropy effect of the molecular shape results in the decrement of the melting point which approaches gradually that of longer n-alkane compound. In this way a sensitive balance between the nonbonded van der Waals interactions, the OH···O hydrogen bonds, as well as the configurational entropy effect gives the characteristic thermal behavior of the H-shape compounds. The thus-newly synthesized H-shape alkane compounds should give us new insight into the packing topology of complicated molecules, leading to the development of new functionality unexpected for normal linear alkane compounds. PMID:21671573

Yamamoto, Hiroko; Tashiro, Kohji; Nemoto, Norio; Motoyama, Yukihiro; Takahashi, Yoshiaki

2011-08-11

246

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

SciTech Connect

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

NONE

1998-12-31

247

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

248

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

PubMed Central

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

Davis, Joseph E.; Patel, Sandeep

2009-01-01

249

ORGANIC CHEMISTRY UCLA Organic Chemistry Faculty  

E-print Network

ORGANIC CHEMISTRY UCLA Organic Chemistry Faculty perform research in molecular machines, exotic CHEMISTRY FACULTY RESEARCH INTERESTS Anne M. Andrews, Professor-in-Residence: Understanding how areas of interest include cross- coupling reactions, green chemistry, heterocycle synthesis, and natural

Levine, Alex J.

250

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

251

Fraction Conversion  

NSDL National Science Digital Library

This lesson is designed to develop students' abilities to convert between fractions and decimals. This lesson provides links to discussions and activities related to fraction conversion as well as suggested ways to integrate them into the lesson. Finally, the lesson provides links to follow-up lessons designed for use in succession with the current one.

2010-01-01

252

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

253

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

254

Tropospheric Multiphase Chemistry: Current Foci  

NASA Astrophysics Data System (ADS)

In this contribution important aspects of tropospheric multiphase chemistry shall be reviewed in the three fields of (1) laboratory investigations covering the matrix in question and chemical conversions occurring. In the second part, (2) recent field work and, finally, (3) recent model developments will be discussed. In the first part a discussion will be led on the actual occurrence of the aqueous reaction medium, especially under aerosol particle conditions. Some recent kinetic investigations on radical and non-radical reactions of interest for aqueous chemistry are discussed. In the second part a short report on the hill-cap cloud experiment HCCT-2010 is given. In the third part a report on current work on CAPRAM is given. A mechanism generator has been put to work, there is a new model version for marine chemistry and an activity-based mechanism version for aerosol particle chemistry. An outlook on future directions will conclude the contribution.

Herrmann, Hartmut; Tilgner, Andreas; van Pinxteren, Dominik; Schöne, Luisa; Weller, Christian; Schaefer, Thomas; Bräuer, Peter; Rusumdar, Jhony

2014-05-01

255

Transporter engineering for improved tolerance against alkane biofuels in Saccharomyces cerevisiae  

PubMed Central

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

2013-01-01

256

"Doing Chemistry."  

ERIC Educational Resources Information Center

Summarizes papers presented at the Sixth Biennial Conference on Chemical Education in the area of "Doing Chemistry," i.e., demonstrations and student experiments. A bibliography of 21 presented papers in this area is attached. (CS)

Journal of Chemical Education, 1981

1981-01-01

257

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

Gahr, Allan A.

2003-02-01

258

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

259

Chemistry Notes.  

ERIC Educational Resources Information Center

Describes equipment, activities, and experiments useful in chemistry instruction, including among others, a rapid method to determine available chlorine in bleach, simple flame testing apparatus, and a simple apparatus demonstrating the technique of flash photolysis. (SK)

School Science Review, 1980

1980-01-01

260

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

261

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.

2010-07-01

262

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.

263

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

264

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

265

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

266

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 receiving supplements, provided the alkane content of the supplement and its intake by individual animals combined with independent estimates of supplement intake. Individually-penned male castrate sheep (n = 18

Boyer, Edmond

267

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

268

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

269

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

270

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

Code of Federal Regulations, 2011 CFR

... 2011-07-01 false Reaction products of substituted hydroxy-alkanes...Substances § 721.9300 Reaction products of substituted hydroxy-alkanes...substance identified generically as reaction products of substituted...c) within 90 days from the time the employer becomes...

2011-07-01

271

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

Code of Federal Regulations, 2010 CFR

... 2010-07-01 false Reaction products of substituted hydroxy-alkanes...Substances § 721.9300 Reaction products of substituted hydroxy-alkanes...substance identified generically as reaction products of substituted...c) within 90 days from the time the employer becomes...

2010-07-01

272

This is your regular audience #AlkanHocaAnlatiyor April 14, 2014  

E-print Network

! ·Tell them what you told them. ·Create a twitter hashtag! #AlkanHocaAnlatiyor April 14, 2014#Alkan, procedures, ideas, devices, and organization, for analyzing problems and devising, implementing, evaluating, and managing solutions to those problems in situations in which learning is purposive and controlled (HMRS 5th

Ã?nay, Devrim

273

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

PubMed

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

274

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 ...

275

Metabolism of n-alkanes and n-alkenes by anaerobic bacteria: A summary  

Microsoft Academic Search

Current knowledge of the pathways for the degradation of n-alkanes and n-alkenes by anaerobic bacteria is summarized and new results questioning the existence of an alternative pathway for anaerobic alkane degradation are introduced. Remaining gaps in our knowledge are also mentioned, together with the possible use of some specific metabolites as biomarkers of anaerobic hydrocarbon degradation.

Vincent Grossi; Cristiana Cravo-Laureau; Rémy Guyoneaud; Anthony Ranchou-Peyruse; Agnès Hirschler-Réa

2008-01-01

276

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 Cn H2n 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

277

CHEMISTRY 320 PHYSICAL CHEMISTRY I  

E-print Network

), physical transformations (including phase transitions), solutions, electrochemistry, and chemical kinetics of the physical principles of chemistry. Goals/ Objectives: CHEM 320 presents chemical principles from, internal energy, enthalpy and entropy), chemical thermodynamics (Gibbs free energy and chemical potentials

Findley, Gary L.

278

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.

279

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

280

Chain Length Dependence of the Thermodynamic Properties of Linear and Cyclic Alkanes and Polymers  

NASA Astrophysics Data System (ADS)

The specific heat capacity was measured with step-scan DSC for linear alkanes from pentane to nonadecane, for several cyclic alkanes, for linear and cyclic polyethylenes, and for a linear and a cyclic polystyrene. For the linear alkanes, the specific heat capacity in the equilibrium liquid state decreases as chain length increases; above a carbon number N of 10 (decane) the specific heat asymptotes to a constant value. For the cyclic alkanes, the heat capacity in the equilibrium liquid state is lower than that of the corresponding linear chains and increases with increasing chain length. At high enough molecular weights, the heat capacities of cyclic and linear molecules are expected to be equal, and this is found to be the case for the polyethylenes and polystyrenes studied. The thermal expansion coefficients and the specific volumes of the linear and cyclic alkanes are also calculated from literature data and compared with the trends in the specific heats.

Simon, Sindee

2005-03-01

281

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.

282

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

283

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

284

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.

285

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

286

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

287

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

288

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

289

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

290

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

291

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

292

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

293

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.

294

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

295

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 and dD n-C27 alkane data show a clear distinction between Populus tremuloides/Syringa vulgaris (Ã?31

Tipple, Brett

296

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

297

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

298

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

299

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.

300

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

301

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 a b s t r a c t The molecular hydrogen isotope composition (dD) of leaf waxes from terrestrial plants of the hydrogen iso- tope composition of n-alkanes (dDn-alkane) from a global dataset of individual plants growing

302

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; Nesb?, Camilla; Abu Laban, Nidal

2014-01-01

303

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.

304

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

305

A Discovery-Based Experiment Involving Rearrangement in the Conversion of Alcohols to Alkyl Halides: Permanent Magnet [to the thirteenth power]C NMR in the First-Semester Organic Chemistry Lab  

ERIC Educational Resources Information Center

The use of permanent magnet [to the thirteenth power]C NMR in large-section first-semester organic chemistry lab courses is limited by the availability of experiments that not only hinge on first-semester lecture topics, but which also produce at least 0.5 mL of neat liquid sample. This article reports a discovery-based experiment that meets both…

Kjonaas, Richard A.; Tucker, Ryand J. F.

2008-01-01

306

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

307

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

308

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

309

Surveys of research in the Chemistry Division, Argonne National Laboratory  

SciTech Connect

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

Grazis, B.M. [ed.

1992-11-01

310

Surveys of research in the Chemistry Division, Argonne National Laboratory  

SciTech Connect

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

Grazis, B.M. (ed.)

1992-01-01

311

Spatial and diurnal distributions of n-alkanes and n-alkan-2-ones on PM 2.5 aerosols in the Lower Fraser Valley, Canada  

NASA Astrophysics Data System (ADS)

Ninety daytime/nighttime PM 2.5 aerosol samples were collected at 5 sites in forest, tunnel, urban, rural, and mixed forest/urban areas in the Lower Fraser Valley during the Pacific 2001 Air Quality Study. Solvent-extractable organic matter, such as n-alkanes (C 14-C 33), n-alkan-2-ones (C 10-C 31), and 6, 10, 14- trimethylpentadecan-2-one on the fine aerosols, were quantified. The concentrations of total n-alkanes from primary sources were 45.5-112 ng m -3 at the tunnel site, 3.3-34.6 ng m -3 at the urban site, 0.6-18.1 ng m -3 at the rural site, and 1.7-16.9 ng m -3 at the forest and the mixed areas. The homologue distributions of the n-alkanes displayed different patterns at the 5 sites, showing day-night differences and reflecting their primary source types and impacts of episodes. The carbon preference index (CPI) values of the n-alkanes showed highest value (average of 2.39±0.47) at the forest, lowest (1.15±0.11) at the tunnel. The CPI showed higher values in night samples at all sites except the urban site which was impacted by specific episodes such as biomass burning and/or fuel burning occurring during the nighttimes, the higher nighttime values of CPI, with consistent lower n-alkane concentrations, suggested that weaker anthropogenic emissions during night were a more likely cause . The total n-alkan-2-ones on the aerosols were 1.8-12.6 ng m -3 at the tunnel site and 0.2-7.2 ng m -3 at the other 4 sites. Low-molecular weight n-alkan-2-ones (alkan-2-one (>C 23) were consistently higher at the tunnel but varied with date at the forest site. The n-alkan-2-ones, both low and high molecular weight, could have multiple sources including vehicular emissions and oxidation processes. The branched ketone, 6, 10, 14- trimethylpentadecan-2-one, an oxidative product of phytol on the fine aerosols, was enriched in the forest with the average of 7.6±7.1 ng m -3.

Cheng, Yu; Li, Shao-Meng; Leithead, Amy; Brook, Jeffrey R.

312

/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

313

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

314

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

315

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-alkane) of n-alkanes record plant source water isotopes. If supported, 2 H analyses of n-alkanes will serve as a powerful tool for biological and ecosystem studies as water source and humidity both can

Tipple, Brett

316

Green Chemistry  

NSDL National Science Digital Library

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

Foundation, Wgbh E.

2010-02-12

317

Confectionary Chemistry.  

ERIC Educational Resources Information Center

Presents activities and demonstrations that enable teachers to use various types of confections as tactile experiences to spark chemistry students' interest and generate enthusiasm for learning. Presents uses of candy in teaching about atomic structure, spontaneous nuclear decay, chemical formulas, fractoluminescence, the effect of a molecular…

Levine, Elise Hilf

1996-01-01

318

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

319

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.

320

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

321

Nuclear Chemistry  

NSDL National Science Digital Library

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

2008-03-12

322

Analytical Chemistry  

NSDL National Science Digital Library

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

Hardy, James K.

2011-03-30

323

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

324

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

325

Chemistry Newsletter # 7  

NSF Publications Database

... the Division of Chemistry Don Burland to retire from the Division of Chemistry Mathematical and ... WITHIN THE DIVISION OF CHEMISTRY The Division of Chemistry has completed its national search and is ...

326

CHEMISTRY DEPARTMENT HANDBOOKFOR STUDENTS  

E-print Network

/ENVIRONMENTAL, Bachelor of Science in Chemistry with Option in Environmental Chemistry 27 BS CHEM/NANOTECHNOLOGY, Bachelor in Biochemistry 85 Minor in Environmental Chemistry 86 1st, 2nd and 3rd Floor Maps of the Chemistry Rooms

Hardy, Christopher R.

327

UCLA CHEMISTRY & BIOCHEMISTRY  

E-print Network

UCLA CHEMISTRY & BIOCHEMISTRY ORIENTATION HANDBOOK 2012-2013 #12;Table of Contents Introduction .............................................................................................................................................2 Chemistry & Biochemistry Undergraduate Office ................................................................................................................................................4 Biochemistry

Levine, Alex J.

328

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

329

Aggregation of a semifluorinated n-alkane in perfluorooctane  

SciTech Connect

The phase behavior of solutions of two semifluorinated n-alkanes, heptadecafluorotetracosane (F(CF[sub 2])[sub 8](CH[sub 2])[sub 16]H) and pentacosafluorooctacosane (F(CF[sub 2])[sub 12](CH[sub 2])[sub 16]H), in perfluorooctane and isooctane is studied. Viscosity, dynamic light-scattering, and small-angle neutron-scattering data show the presence of small, nearly spherical aggregates in heptadecafluorotetracosane/perfluorooctane solutions in the liquid phase above the critical micelle concentration. The authors determined the size and average aggregation number of these aggregates as a function of the fluorohydrocarbon concentration. Small-angle neutron-scattering results show that the perfluorooctane solvent penetrates appreciably into the micellar core. 21 refs., 6 figs., 2 tabs.

Nostro, P.L.; Chen, S.H. (Massachusetts Inst. of Technology, Cambridge (United States))

1993-06-17

330

Oxidation of Alkanes to Internal Monoalkenes by a Nocardia1  

PubMed Central

A suspension of glucose-grown resting cells of Nocardia salmonicolor PSU-N-18 oxidized hexadecane to a mixture of internal monohexadecenes. The latter exhibited a cis configuration, and the mixture consisted of the following: 7-hexadecene, 80%; 8-hexadecene, 18%; and 6-hexadecene, 2%. Alkanes other than hexadecane also were unsaturated by the resting cells, and the composition of the monoalkenes resulting from octadecane dehydrogenation was 9-octadecene, 91%; 8-octadecene, 2 to 3%; 7-octadecene, 1 to 2%; and 6- and 5-octadecenes, trace amounts. Only minute quantities of unsaturated hydrocarbons accumulated during growth on hexadecane and during resting-cell incubation of hexadecane-grown cells with hexadecane. The dehydrogenation of hydrocarbons did not appear to be related to the formation of unsaturated fatty acids. It is postulated that double bond insertion may represent an early step in a new pathway of aliphatic hydrocarbon degradation. PMID:5686017

Abbott, Bernard J.; Casida, L. E.

1968-01-01

331

Chemistry 675 Advanced Organic Chemistry  

E-print Network

. Chisholm 4-006 CST jdchisho@syr.edu 443-6894 Office Hours: By appointment, between 9 AM and 5 PM Course in my office (CST 4-006) or my mailbox in the chemistry office (CST 1-014). Late problem sets will have

Doyle, Robert

332

Environmental Chemistry II (Atmospheric Chemistry)  

E-print Network

Seinfeld, J. H. and Pandis, S. N. Atmospheric Chemistry and Physics: From Air Pollution to Climate Change Monday, December 16 at 4:00 p.m. (Climate Change and comprehensive) Exams I and II are planned as two for undergraduate students than graduate students. Grading Scale 85 -100% at least an A- 75 - 84% at least a B- 65

Dibble, Theodore

333

(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.

334

Control of photoreaction of amphiphilic spiropyran/n-alkane Langmuir and Langmuir-Blodgett films using the phase transition of n-alkane.  

PubMed

The structures and photoreactions of Langmuir and Langmuir-Blodgett (LB) films of an amphiphilic spiropyran, 1',3'-dihydro-3',3'-dimethyl-6-nitro-1'-octadecyl-8-(docosanoyloxymethyl)spiro[2H-1-benzopyran-2,2'-(2H)-indole] (SP), mixed with n-alkane are investigated. The mixing ratio was fixed at 1/2 for SP/n-alkane. The surface pressure-area isotherms of SP/octadecane are categorized into two regimes: a low-temperature regime where octadecane is packed with the alkyl chains of SP, and a high-temperature regime where the addition of octadecane does not influence the isotherms significantly. The temperature dividing the two regimes is related with the melting point of the n-alkane mixed with SP in the bulk. UV irradiation of the Langmuir film in the high-temperature regime gives rise to light-induced J-aggregation, whereas that in the low-temperature regime causes only the isomerization of SP to the corresponding merocyanine, indicating that J-aggregation is hindered by the presence of n-alkane in the low-temperature regime. IR external reflection spectroscopy of the Langmuir films shows that n-alkane is released from the film during J-aggregation. The structural changes of the mixed Langmuir and LB films during J-aggregation are almost the same with those of the films of pure SP. PMID:15544388

Nakazawa, Takahiro; Azumi, Reiko; Sakai, Hideki; Abe, Masahiko; Matsumoto, Mutsuyoshi

2004-11-23

335

Environmental Chemistry  

NSDL National Science Digital Library

In this activity with several mini experiments, learners explore the chemistry that helps scientists learn about the environment and how they can help save it. Learners will determine if pollutants that have entered the ground water can also enter plants. Then, learners examine fossils to see if any changes have occurred over time in a particular species of sea mollusks. Finally, learners act as chemists to recycle paper by making paper from toilet paper.

Shaw, Maisie; Gomez, Maria

2010-01-01

336

Circumstellar chemistry  

NASA Technical Reports Server (NTRS)

Recent theoretical studies of circumstellar chemistry are discussed for both red-giant and protostellar winds. The generalized photochemical model is able to account for the recently discovered silicon-bearing molecules in the prototypical, C-rich, AGB star IRC + 10216. The surprising occurrence of CO in protostellar winds that are largely atomic is interpreted to be the result of the high density and the rapid decrease of the temperature with distance that is expected for such winds.

Glassgold, A. E.; Mamon, G. A.

1991-01-01

337

Molecular simulation of diffusion and sorption of alkanes and alkane mixtures in poly[1-(trimethylsilyl)-1-propyne  

NASA Astrophysics Data System (ADS)

In the present study, we investigated the sorption and transport of pure and mixed alkanes and gases (H2, CH4, C2H 6, C3H8, i-C4H 10, and n-C4H10) in poly[1-(trimethylsilyl)1-propyne] (PTMSP) through the use of molecular dynamics (MD) and Grand Canonical Monte Carlo (GCMC) simulations. The bonded constants in the DREIDING II and COMPASS force fields have been parameterized for PTMSP from AMI. and GAUSSL4,N94 calculations of the dimer. The densities of amorphous cells generated from the two force fields agreed well with experimental data. Diffusion coefficients were calculated by means of the Einstein relationship using (NVT ensemble) MD simulation. There was good agreement between experimental and simulation diffusion coefficients for the gases and alkanes. MD trajectories indicated conformational changes of PTMSP that enable the formation of channels between adjacent holes of the free volume. The high mobility of the trimethylsilyl group studied by rotational time correlation analysis could facilitate channel formation. Sorption isotherms of alkanes in PTMSP were obtained by fixed-pressure GCMC simulation. The results for the pure-component isotherms were in qualitative agreement with experiment data. There was good agreement between simulation and experimental results for the solubility and dual-mode sorption parameters. Diffusion coefficients and solubilities obtained from transition-state theory (TST) simulation for light gases (H2 and CH4) agreed well with MD and GCMC simulations, whereas the agreement was not as good for larger condensable vapors. High overall free volume and free volume distribution contributed to the high gas permeability of PTMSP. There was excellent correlation between In D and fa, the accessible free volume fraction, for PTMSP and each of the four alkanes. Fractional free volume obtained by Voorintholt grid search method was consistent with the experimental values. TST results indicated that the larger the gas molecule, the larger was the free volume element in which gas resided and the longer was the residence time. The simulated diffraction pattern was in good agreement with experimental data and indicated a large interchain distance for PTMSP. It was found from simulation that the solvent casting during PTMSP membrane preparation did not make much difference in terms of the final membrane density and fractional free volume. Four gas/vapor mixtures were investigated by MD and GCMC simulations---CH 4/C3H8, CH4/n-C 4H10, H2/C3H8, and H 2/n-C4H10. It was found from GCMC simulation that the larger gas molecule was more competitive to the sorption site for binary gas mixtures. Compared with pure gas permeability, the permeability of the permanent gas in binary mixture decreased more than that of the condensable vapor. This behavior was consistent with a blocking mechanism suggested for permanent gas/condensable vapor transport in PTMSP.

Zheng, Tao

338

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.

339

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 during the lowtemperature oxidation of an organic compound has been achieved thanks lowtemperature oxidation regime has been obtained under conditions close to those actually observed before

Paris-Sud XI, Université de

340

Conformational problem of alkanes in liquid crystals by NMR spectroscopy: a mini-review.  

PubMed

Recent discoveries of the role of alkane flexibility in determining liquid-crystal behaviour are surveyed. With the impetus for understanding the alkane conformational problem established, recent model dependent (1)H NMR work on the topic will be reviewed where progress is made but the need to circumvent models eventually becomes evident. A closer look at the rigid basic units of alkanes will provide the way forward where it is shown that the orientational ordering and anisotropic potentials of these molecules dissolved in liquid crystals scale with each other. Once this relationship is established, a series of works using anisotropic and isotropic (1)H NMR spectroscopy to study alkane conformational statistics will be covered, wherein the influence of the gas, isotropic condensed and anisotropic condensed phases will be described. PMID:25142124

Weber, Adrian C J; Chen, Daniel H J

2014-10-01

341

Complete Genome Sequence of an Alkane Degrader, Alcanivorax sp. Strain NBRC 101098  

PubMed Central

Alcanivorax sp. strain NBRC 101098 was isolated from seawater in Japan. Strain NBRC 101098 is able to degrade various types of n-alkanes. Here, we report the complete genome of strain NBRC 101098. PMID:25125640

Miura, Takamasa; Tsuchikane, Keiko; Numata, Mitsuru; Hashimoto, Maiko; Hosoyama, Akira; Ohji, Shoko; Yamazoe, Atsushi

2014-01-01

342

Liquid alkanes with targeted molecular weights from biomass-derived carbohydrates.  

PubMed

Liquid transportation fuels must burn cleanly and have high energy densities, criteria that are currently fulfilled by petroleum, a non-renewable resource, the combustion of which leads to increasing levels of atmospheric CO(2). An attractive approach for the production of transportation fuels from renewable biomass resources is to convert carbohydrates into alkanes with targeted molecular weights, such as C(8)-C(15) for jet-fuel applications. Targeted n-alkanes can be produced directly from fructose by an integrated process involving first the dehydration of this C(6) sugar to form 5-hydroxymethylfurfural, followed by controlled formation of C-C bonds with acetone to form C(9) and C(15) compounds, and completed by hydrogenation and hydrodeoxygenation reactions to form the corresponding n-alkanes. Analogous reactions are demonstrated starting with 5-methylfurfural or 2-furaldehyde, with the latter leading to C(8) and C(13) n-alkanes. PMID:18702136

West, Ryan M; Liu, Zhen Y; Peter, Maximilian; Dumesic, James A

2008-01-01

343

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

344

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

345

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

346

Biochemistry of Short-Chain Alkanes (Tissue-Specific Biosynthesis of n-Heptane in Pinus jeffreyi).  

PubMed Central

Short-chain (C7-C11) alkanes accumulate as the volatile component of oleoresin (pitch) in several pine species native to western North America. To establish the tissue most amenable for use in detailed studies of short-chain alkane biosynthesis, we examined the tissue specificity of alkane accumulation and biosynthesis in Pinus jeffreyi Grev. & Balf. Short-chain alkane accumulation was highly tissue specific in both 2-year-old saplings and mature trees; heart-wood xylem accumulated alkanes up to 7.1 mg g-1 dry weight, whereas needles and other young green tissue contained oleoresin with monoterpenoid, rather than paraffinic, volatiles. These tissue-specific differences in oleoresin composition appear to be a result of tissue-specific rates of alkane and monoterpene biosynthesis; incubation of xylem tissue with [14C]sucrose resulted in accumulation of radiolabel in alkanes but not monoterpenes, whereas incubation of foliar tissue with 14CO2 resulted in the accumulation of radiolabel in monoterpenes but not alkanes. Furthermore, incubation of xylem sections with [14C]acetate resulted in incorporation of radiolabel into alkanes at rates up to 1.7 nmol h-1 g-1 fresh weight, a rate that exceeds most biosynthetic rates reported with other plant systems for the incorporation of this basic precursor into natural products. This suggests that P. jeffreyi may provide a suitable model for elucidating the enzymology and molecular biology of short-chain alkane biosynthesis. PMID:12226177

Savage, T. J.; Hamilton, B. S.; Croteau, R.

1996-01-01

347

Different response of ?D values of n-alkanes, isoprenoids, and kerogen during thermal maturation  

NASA Astrophysics Data System (ADS)

This study investigates the extent of post-depositional alteration of ?D values of n-alkyl lipids, isoprenoids, and kerogen isolated from a continuous 450 m core that covers the transition from thermally immature to early mature sediments in the lacustrine Kissenda Formation, Lower Cretaceous, Gabon Basin. Large variations in ?D values (up to 40‰ for nC 17 and up to 30‰ for nC 29 alkanes as well as up to 10‰ for kerogen) in closely spaced samples are evident throughout the core and remain preserved even at the bottom of the section. ?D values of individual n-alkanes show a slight overall D-enrichment with depth, and a general trend of increasing ?D values with increasing n-alkane chain length characterizes all samples, particularly in those below 600 m depth. Hydrogen isotopic compositions of kerogen samples overlap with those of n-alkanes throughout the section. ?D values of pristane and phytane are more negative than those of nC 17 alkane by as much as 120‰ at shallow depths but increase dramatically and approach ?D values of nC 17 alkane in the samples closest to the oil window. Integration of analytical and computational results indicates that: (1) n-alkanes and isoprenoids have the potential to preserve the original biological signal before the onset of oil generation; (2) isomeric and structural rearrangements taking place at the beginning stages of oil generation do not influence significantly the ?D values of n-alkanes and kerogen. However, these processes have a major effect on the isotopic composition of isoprenoids, causing isotopic D-enrichment up to 90‰.

Pedentchouk, Nikolai; Freeman, Katherine H.; Harris, Nicholas B.

2006-04-01

348

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

Microsoft Academic Search

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

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

1995-01-01

349

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

350

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

351

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

352

Use of radiation-induced alkanes and alkenes to detect irradiated food containing lipids  

Microsoft Academic Search

To detect irradiated foodstuffs, we used the Nawar relation between lipid structure and radiolysis compounds, such as alkanes\\u000a and alkenes. We first applied this method to sunflower, olive and peanut oils. Alkanes and alkenes were analyzed by gas chromatography\\u000a with a head-space system for desorption and concentration of the volatile compounds. The detection limit, obtained both by\\u000a estimation of the

Guy Lesgards; Jacques Raffi; Isabelle Pouliquen; Abdel-Aziz Chaouch; Philippe Giamarchi; Michel Prost

1993-01-01

353

Investigation of the radical products of alkane radiolysis by spin trapping  

Microsoft Academic Search

The formation of radicals in ..gamma..-irradiated Câ-Câ alkanes, cyclohexane, and isooctane were studied by means of spin traps. The following spin traps were used: 2,4,6-tri-tert-butylnitrosobenzene (BNB), nitrosodurene (ND), C-phenyl-N-tert-butylnitrone (phi BN), and tert-nitrosobutane (TNB). The syntheses of the spin traps BNB, ND, phi BN, and TNB, were conducted by known methods. The solutions of the spin traps in the alkanes

V. N. Belevskii; O. V. Isakova; L. I. Bugaenko

1978-01-01

354

Synthesis of Imidazol-2-yl Amino Acids by Using Cells from Alkane-Oxidizing Bacteria  

Microsoft Academic Search

Sixty-one strains of alkane-oxidizing bacteria were tested for their ability to oxidize N-(2-hexylamino-4- phenylimidazol-1-yl)-acetamide to imidazol-2-yl amino acids applicable for pharmaceutical purposes. After growth with n-alkane, 15 strains formed different imidazol-2-yl amino acids identified by chemical structure analysis (mass and nuclear magnetic resonance spectrometry). High yields of imidazol-2-yl amino acids were produced by the strains Gordonia rubropertincta SBUG 105, Gordonia

Annett Mikolasch; Elke Hammer; Frieder Schauer

2003-01-01

355

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

356

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

PubMed Central

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

2014-01-01

357

A new mechanism for regional tropospheric chemistry modeling  

SciTech Connect

The authors present a new atmospheric chemical mechanism for the modeling of regional air pollution, the Regional Atmospheric Chemistry Mechanism (RACM). Ozone is produced through the photo-oxidation of nitrogen oxides and volatile organic compounds. The organic chemistry of the RACM mechanism is a significant improvement over existing mechanisms. Since the organic chemistry of the atmosphere is very complicated and computer resources are limited, the RACM mechanism uses grouped organic classes to describe atmospheric organic chemistry. The individual emitted organic species are aggregated into the 32 RACM classes through a reactivity weighting approach. The oxidation schemes of alkanes, alkenes and aromatics were reevaluated and improved through the use of new laboratory data. These improvements include a significant reduction in the ratio of aldehydes to ketones produced from alkanes; the production of relatively large amounts of nitrates from the reactions of unbranched alkenes with NO{sub 3}; the production of HO from alkene ozonolysis; a reduction of cresol production from the oxidation of aromatics and better treatment of unsaturated dicarbonyl species. The peroxyacetyl nitrate chemistry and the organic peroxy radical--peroxy radical reactions were revised which caused a significant reduction in predicted PAN concentrations. For biogenic species, a new isoprene scheme includes an improved representation of methacrolein, isoprene ozonolysis, hydroperoxide production and the carbonitrate production. The new RACM mechanism has been tested against smog chamber data. Predicted ozone profiles and the timing of the ozone peak are well within the uncertainties of experiments. The authors also discuss mechanism and laboratory data uncertainties, future data needs and new plans for the development of improved chemical mechanisms for air quality models.

Stockwell, W.R.; Kuhn, M.; Seefeld, S.; Kirchner, F. [Fraunhofer Inst. for Atmospheric Environmental Research (IFU), Garmisch-Partenkirchen (Germany)

1997-12-31

358

Combustion Characteristics of Liquid Normal Alkane Fuels in a Model Combustor of Supersonic Combustion Ramjet Engine  

NASA Astrophysics Data System (ADS)

Effect of kinds of one-component n-alkane liquid fuels on combustion characteristics was investigated experimentally using a model combustor of scramjet engine. The inlet condition of a model combustor is 2.0 of Mach number, up to 2400K of total temperature, and 0.38MPa of total pressure. Five kinds of n-alkane are tested, of which carbon numbers are 7, 8, 10, 13, and 16. They are more chemically active and less volatile with an increase of alkane carbon number. Fuels are injected to the combustor in the upstream of cavity with barbotage nitrogen gas and self-ignition performance was investigated. The result shows that self-ignition occurs with less equivalence ratio when alkane carbon number is smaller. This indicates that physical characteristic of fuel, namely volatile of fuel, is dominant for self-ignition behavior. Effect on flame-holding performance is also examined with adding pilot hydrogen and combustion is kept after cutting off pilot hydrogen with the least equivalence ratio where alkane carbon number is from 8 to 10. These points are discussed qualitatively from the conflict effect of chemical and physical properties on alkane carbon number.

??, ?; ??, ??; ??, ??; ??, ???; ??, ??; ??, ??; ??, ??

359

School of Chemistry CHEM3100: Chemistry at a Molecular Level  

E-print Network

School of Chemistry CHEM3100: Chemistry at a Molecular Level Tutorial Groups 2013/14 Name Programme Tutor Ahmed, Zacher Medicinal Chemistry Arif, Saboor Chemistry Bagnall, Samuel Chemistry Barbara, David Chemistry Beaumont, Nicholas Chemistry Quinn, Michael J Chemistry Bennett, Matthew Chemistry Booth, Natalie

Rzepa, Henry S.

360

Industrial Chemistry  

NSDL National Science Digital Library

This Web site addresses Professor Dr. J. Gmehling's research group activities in "the synthesis and design of chemical processes with an emphasis on thermal separation processes." Ranging from the development of thermodynamic models to the construction of software tools and data banks, their research at the University of Oldenburg, covers a broad range in the field of Industrial Chemistry. Students and educators can view informative figures and images such as the Isothermal Flow Calorimeter and the Gas-Liquid Chromatography. Users can download the free software, Dortmund Data Bank (DDB), which searches the literature for experimental information.

361

(Pesticide chemistry)  

SciTech Connect

This report summarizes a trip by L. W. Barnthouse of the Environmental Sciences Division (ESD), Oak Ridge National Laboratory (ORNL), to Hamburg, Federal Republic of Germany (FRG), where he participated in the 7th International Congress of Pesticide Chemistry. He chaired a workshop on experimental systems for determining effects of pesticides on nontarget organisms and gave an oral presentation at a symposium on pesticide risk assessment. Before returning to the United States, Dr. Barnthouse visited the Netherlands Institute for Sea Research in Texel, the Netherlands.

Barnthouse, L.W.

1990-09-04

362

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

363

The University of North Carolina at Chapel Hill: Chemistry Fundamentals Program  

NSDL National Science Digital Library

The University of North Carolina at Chapel Hill Chemistry Fundamentals Program offers an interactive review of the fundamentals of chemistry for incoming college freshman chemistry students. The basic link offers materials about chemical nomenclature, atomic structure, stoichiometry, and acid base chemistry. After learning about these essentials, users can progress to more advanced topics such as gas laws, thermodynamics, kinetics, and redox chemistry. The explanations are linked with a useful chemistry glossary. The website offers many online calculators to deal with compressibility, unit conversion, and various other chemical problems. Students can also find a helpful review of mathematics used in chemistry.

364

The University of North Carolina at Chapel Hill: Chemistry Fundamentals Program  

NSDL National Science Digital Library

The University of North Carolina at Chapel Hill Chemistry Fundamentals Program offers an interactive review of the fundamentals of chemistry for incoming college freshman chemistry students. The basic link offers materials about chemical nomenclature, atomic structure, stoichiometry, and acid base chemistry. After learning about these essentials, users can progress to more advanced topics such as gas laws, thermodynamics, kinetics, and redox chemistry. The explanations are linked with a useful chemistry glossary. The website offers many online calculators to deal with compressibility, unit conversion, and various other chemical problems. Students can also find a helpful review of mathematics used in chemistry.

2007-05-19

365

University of California Organic Chemistry Lab  

E-print Network

for students blind, visually impaired or have a learning disability) i. Internet Explorer 9 & 10 and Firefox and Conversations to Communicate in Your Course How to Check Your Grade Organic Chemistry Laboratory is hybrid, by Steven F. Pedersen, Jesse H. Pedersen. (ISBN: 9781111428167) Textbook is available from: Cal Student

Jacobs, Lucia

366

University of California Organic Chemistry Lab  

E-print Network

for students blind, visually impaired or have a learning disability) i. Internet Explorer 9 & 10 and Firefox, Discussions and Conversations to Communicate in Your Course How to Check Your Grade Organic Chemistry from: Cal Student Store 2. Computer Requirements Internet i. High-speed Internet ii. Minimum of 512kbps

Walker, Matthew P.

367

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.

368

Computer-aided molecular design of alkane-activation catalysts. [Manganese tetra(pentafluorophenyl) porphyrin; manganese tetra(2'-carboranylphenyl-anilide) porphyrin chloride; manganese chloride derivative of tetra(2',6'-dinitrophenyl) porphyrin free base  

SciTech Connect

Our work focuses on a novel biomimetic approach to the development of catalysts for activation of methane, using computer-aided molecular design (CAMD) techniques. The biomimetic CAMD methodology consists of several elements: (1) Design activities are guided by the structural and chemical information about naturally occurring biological catalysts that carry out alkane oxidation to alcohols. The macromolecular biological catalysts are investigated to determine the features that need to be designed into a synthetic catalyst in order to mimic the alkane-oxidation function. (2) Molecular mechanics calculations are used to evaluate possible designs for catalysts based on synthetic metalloporphyrins. The metalloporphyrins have been chosen because they occur at the active site of many monooxygenases and other enzymes that catalyze C/sub 1/ chemistry. Also, the porphyrin macrocycle provides a platform upon which additional molecular architecture is erected to provide the structural features required to mimic the enzymes. (3) The computer designed catalysts are then synthesized. (4) The synthetic catalysts are characterized by various spectroscopic techniques including Raman-difference, transient Raman, FTIR, NMR, and uv-visible absorption spectroscopies. (5) The designed catalysts are tested in alkane-oxidation reactions. The activity test results and results of the structural studies are evaluated to obtain structure-activity relationships that form a basis for making further improvements in the catalyst. This feedback procedure gives an iterative method for optimizing catalytic properties. 20 refs., 3 figs.

Shelnutt, J.A.; Stohl, F.V.; Granoff, B.

1988-01-01

369

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, Amelie; Domergue, Frederic; Pascal, Stephanie; Jetter, Reinhard; Renne, Charlotte; Faure, Jean-Denis; Haslam, Richard P.; Napier, Johnathan A.; Lessire, Rene; Joubes, Jerome

2012-01-01

370

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

371

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

372

Modelling the phase behaviour and excess properties of alkane + perfluoroalkane binary mixtures with the SAFT–VR approach  

Microsoft Academic Search

The phase and volumetric behaviour of binary mixtures of n-alkanes and n-perfluoroalkanes at subcritical conditions have been studied using the SAFT–VR equation of state. In previous work [C. McCabe, A. Galindo, A. Gil-Villegas, G. Jackson, Predicting the high-pressure phase equilibria of binary mixtures of perfluoro-n-alkanes plus n-alkanes using the SAFT–VR approach, J. Phys. Chem. B 102 (1998) 8060–8069] the SAFT–VR

Pedro Morgado; Clare McCabe; Eduardo J. M. Filipe

2005-01-01

373

Anaerobic n-Alkane Metabolism by a Sulfate-Reducing Bacterium, Desulfatibacillum aliphaticivorans Strain CV2803T  

Microsoft Academic Search

The alkane-degrading, sulfate-reducing bacterium Desulfatibacillum aliphaticivorans strain CV2803T, recently isolated from marine sediments, was investigated for n-alkane metabolism. The total cellular fatty acids of this strain had predominantly odd numbers of carbon atoms (C odd) when the strain was grown on a C-odd alkane (pentadecane) and even numbers of carbon atoms (C even) when it was grown on a C-even

Cristiana Cravo-Laureau; Vincent Grossi; Danielle Raphel; Robert Matheron; Agnes Hirschler-Rea

2005-01-01

374

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

375

APPROXIMATE CHEMISTRY 113  

E-print Network

APPROXIMATE CHEMISTRY 113 Spring 2014 Forensic Science Professors James T. Spencer (jtspence SKILLS: Chemistry 113, Forensic Science, is focused upon the application of scientific methods specifically relevant to crime detection and analysis will be presented. No prior chemistry instruction

Doyle, Robert

376

Sawyer Environmental Chemistry Research  

E-print Network

1 Sawyer Environmental Chemistry Research Laboratory Sawyer Environmental Research Center University of Maine #12;2 Mission Statement The Sawyer Environmental Chemistry Research Laboratory is a multi industry. The Sawyer Environmental Chemistry Research Laboratory employs advanced analytical techniques

Thomas, Andrew

377

Why Teach Environmental Chemistry?  

ERIC Educational Resources Information Center

Discusses the importance of teaching environmental chemistry in secondary school science classes, and outlines five examples of environmental chemistry problems that focus on major concepts of chemistry and have critical implications for human survival and well-being. (JR)

Gardner, Marjorie H.

1974-01-01

378

Computational Chemistry List  

NSDL National Science Digital Library

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

379

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

380

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

381

Environmental chemistry. Seventh edition  

SciTech Connect

This book presents a basic understanding of environmental chemistry and its applications. In addition to providing updated materials in this field, the book emphasizes the major concepts essential to the practice of environmental chemistry. Topics of discussion include the following: toxicological chemistry; toxicological chemistry of chemical substances; chemical analysis of water and wastewater; chemical analysis of wastes and solids; air and gas analysis; chemical analysis of biological materials and xenobiotics; fundamentals of chemistry; and fundamentals of organic chemistry.

Manahan, S.E. [Univ. of Missouri, Columbia, MO (United States)

1999-11-01

382

Science Update: Inorganic Chemistry.  

ERIC Educational Resources Information Center

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

Rawls, Rebecca

1981-01-01

383

Biology 3515/Chemistry 3515 Biological Chemistry Laboratory  

E-print Network

Biology 3515/Chemistry 3515 Biological Chemistry Laboratory Spring 2013 (Draft Syllabus, 23 August 2012) Course Description and Objectives: This course is intended for students who have taken Biology and function, particularly for enzymes. Prerequisites: Biology 3510 or Chemistry 3510 Instructor: David P

Simons, Jack

384

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

385

Hydrogen isotope ratios of lipid biomarkers (n alkanes) as paleohydrologic proxies: aquatic vs. terrestrial archives  

NASA Astrophysics Data System (ADS)

Hydrogen isotope ratios (?D) of lake and soil waters reflect both the isotopic composition of precipitation and the subsequent hydrologic processes that modify those waters. ?D values of lake waters are affected by precipitation/evaporation ratio, circulation, lake type, and groundwater interactions. Soil water ?D values are modified from precipitation values by evaporation, transpiration by plants and selective transport of soil waters. Organic compounds synthesized by algae and vascular plants retain a ?D signature of source water. Therefore, compound-specific ?D measurements of individual biomarkers present a promising tool for reconstructing paleohydrologic and paleoclimatic factors that determine ?D values of environmental waters. Here, we use two sample sets to explore the use of ?D of individual n-alkanes from different depositional environments to compare the paleoproxy potential of n-alkanes from aquatic vs. terrestrial plants. ?D values of n-alkanes (C15-C25) from a ˜400 m core of Lower Cretaceous lacustrine shale from the Gabon Basin were determined. C15 and C17 n-alkanes (phytoplankton source) exhibit a nearly identical pattern of ?D values down-core. C23 and C25 n-alkanes (aquatic macrophyte source) also share similar values and trends but are isotopically enriched relative to C15/C17. These ?D records correspond closely with the carbonate ?18O record suggesting the ?D values of n-alkanes preserve a record of changes in lake-water isotopic composition. ?D n-alkane records also co-vary with %TOC and Hydrogen Index indicating that a negative water balance leads to increased OM preservation. ?D of high molecular-weight n-alkanes (C27-C33), indicative of vascular plant leaf-waxes, can potentially be used to reconstruct changes in aridity and/or seasonality of precipitation in grasslands. A modern calibration set is being developed on the ?D of n-alkanes from grasses collected throughout the Great Plains of North America. The calibration set includes C_3 and C_4 grasses from sites with a range of precipitation ?D values and hydrologic conditions. Ultimately, this proxy will be applied to examine the effect of changing paleoprecipitation patterns on the late Miocene spread of C_4 grasses.

Smith, F. A.; Pedentchouk, N.; Freeman, K. H.

2003-04-01

386

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

387

Adsorption of Alcohols and Alkanes on Single-Walled Carbon Nanotubes  

NASA Astrophysics Data System (ADS)

Recent experiments with arrays of carbon nanotubes (CNTs) reveal a strong electrical response during exposure to polar alkane derivatives such as linear alcohols CnH2n+1OH, which is in contrast with the weak response to linear alkanes CnH2n+2. To develop an understanding of the microscopic mechanisms involved, we perform detailed ab initio calculations of adsorption geometries and charge configurations for the size parameter n from 1 to 8 on pristine zig-zag and armchair CNTs. We use Density Functional Theory with localized orbitals in a cluster approach, along with the M05-2X functional appropriate for the weak interactions of physisorption for these systems. We find that adsorption energies are larger for alcohols than for alkanes and increase linearly in energy with length of the molecule n for both alcohols and alkanes (at 35 meV and 40 meV per additional CH2, respectively). This is found to be in good agreement with the binding energy per additional CH2 estimated from the fast conductance response measurements for both alcohols and alkanes using a simple kinetic theory model. We estimate small charge transfers for all molecules, which suggest that the electric response is dominated by the scattering from the dipole moments of the adsorbates. [This work is supported by the Office of Naval Research.

Alldredge, Erik; Badescu, Stefan; Reinecke, Thomas; Bajwa, Navdeep; Perkins, F. Keith; Snow, Eric

2008-03-01

388

Enhanced biodegradation of alkane hydrocarbons and crude oil by mixed strains and bacterial community analysis.  

PubMed

In this study, two strains, Acinetobacter sp. XM-02 and Pseudomonas sp. XM-01, were isolated from soil samples polluted by crude oil at Bohai offshore. The former one could degrade alkane hydrocarbons (crude oil and diesel, 1:4 (v/v)) and crude oil efficiently; the latter one failed to grow on alkane hydrocarbons but could produce rhamnolipid (a biosurfactant) with glycerol as sole carbon source. Compared with pure culture, mixed culture of the two strains showed higher capability in degrading alkane hydrocarbons and crude oil of which degradation rate were increased from 89.35 and 74.32?±?4.09 to 97.41 and 87.29?±?2.41 %, respectively. In the mixed culture, Acinetobacter sp. XM-02 grew fast with sufficient carbon source and produced intermediates which were subsequently utilized for the growth of Pseudomonas sp. XM-01 and then, rhamnolipid was produced by Pseudomonas sp. XM-01. Till the end of the process, Acinetobacter sp. XM-02 was inhibited by the rapid growth of Pseudomonas sp. XM-01. In addition, alkane hydrocarbon degradation rate of the mixed culture increased by 8.06 to 97.41 % compared with 87.29 % of the pure culture. The surface tension of medium dropping from 73.2?×?10(-3) to 28.6?×?10(-3) N/m. Based on newly found cooperation between the degrader and the coworking strain, rational investigations and optimal strategies to alkane hydrocarbons biodegradation were utilized for enhancing crude oil biodegradation. PMID:24532465

Chen, Yu; Li, Chen; Zhou, Zhengxi; Wen, Jianping; You, Xueyi; Mao, Youzhi; Lu, Chunzhe; Huo, Guangxin; Jia, Xiaoqiang

2014-04-01

389

Diffusion of dioxygen in 1-alkenes and biphenyl in perfluoro- n-alkanes  

NASA Astrophysics Data System (ADS)

The translational diffusion constant, D, has been measured for O 2 in the even 1-alkenes 1-C 6H 12 to 1-C 16H 32 and biphenyl in n-C 6F 14 and n-C 9F 20. Deviations from the Stokes-Einstein relation were found; the use of D/ T= A/ ?p gave p=0.560±0.017 for O 2 in the 1-alkenes, the same (within experimental error) as found previously for O 2 in the n-alkanes. The charge transfer (CT) transition used to detect O 2 in the 1-alkenes is at 220 nm. The D values for biphenyl in the perfluoro- n-alkanes (PFAs) are consistent with those in the n-alkanes, where p=0.718±0.004. These results suggest that O 2 has similar solute-solvent interactions in both the 1-alkenes and n-alkanes as does biphenyl in the n-alkanes and PFAs.

Kowert, Bruce A.; Sobush, Kurtis T.; Dang, Nhan C.; Seele, Louis G., III; Fuqua, Chantel F.; Mapes, Courtney L.

2002-02-01

390

Toward aldehyde and alkane production by removing aldehyde reductase activity in Escherichia coli.  

PubMed

Advances in synthetic biology and metabolic engineering have enabled the construction of novel biological routes to valuable chemicals using suitable microbial hosts. Aldehydes serve as chemical feedstocks in the synthesis of rubbers, plastics, and other larger molecules. Microbial production of alkanes is dependent on the formation of a fatty aldehyde intermediate which is converted to an alkane by an aldehyde deformylating oxygenase (ADO). However, microbial hosts such as Escherichia coli are plagued by many highly active endogenous aldehyde reductases (ALRs) that convert aldehydes to alcohols, which greatly complicates strain engineering for aldehyde and alkane production. It has been shown that the endogenous ALR activity outcompetes the ADO enzyme for fatty aldehyde substrate. The large degree of ALR redundancy coupled with an incomplete database of ALRs represents a significant obstacle in engineering E. coli for either aldehyde or alkane production. In this study, we identified 44 ALR candidates encoded in the E. coli genome using bioinformatics tools, and undertook a comprehensive screening by measuring the ability of these enzymes to produce isobutanol. From the pool of 44 candidates, we found five new ALRs using this screening method (YahK, DkgA, GldA, YbbO, and YghA). Combined deletions of all 13 known ALRs resulted in a 90-99% reduction in endogenous ALR activity for a wide range of aldehyde substrates (C2-C12). Elucidation of the ALRs found in E. coli could guide one in reducing competing alcohol formation during alkane or aldehyde production. PMID:25108218

Rodriguez, Gabriel M; Atsumi, Shota

2014-09-01

391

Effects of fuel properties on the burning characteristics of collision-merged alkane/water droplets  

SciTech Connect

The combustion characteristics of freely falling droplets, individually generated by the merging of colliding alkane and water droplets, were experimentally investigated. The outcome of the collision droplets was first studied and then the subsequent burning processes such as the flame appearance, ignition and burning behaviors were recorded, through either visual observation or microphotography with the aid of stroboscopic lighting. If the merged droplets were exhibited in an insertive manner, while the water droplet inserted into the alkane droplet, these yield the burning behaviors prior to the end of flame were very much similar to that of pure alkane. The burning was ended with droplet extinction for lower-C alkane, and with either droplet ''flash vaporization'' or extinction for hexadecane. And if the merged droplets were in adhesive manner, for hexadecane with large water content, they either could not be ignited for the large merged droplets, or be ignited with a much prolonged ignition delay, followed by a soot-reducing flame and an ending of droplet extinction for the small merged droplets. ''Homogeneous'' explosion was not observed in any of the tests, and ''heterogeneous'' explosion, induced by trapped air bubbles, occasionally occurred for merged droplets with C-atom in alkane is higher than dodecane. And the sudden disappearance of droplet definitely decreased the burning time and thus enhanced the burning intensity. Besides, the fuel mass consumption rates were increased, even in the cases that having droplet extinction, because of the enlargement of the surface area due to the stuffing of water droplet. (author)

Wang, C.H.; Pan, K.L.; Huang, W.C.; Wen, H.C. [Department of Mechanical Engineering, National Taiwan University, Taipei 106 (China); Yang, J.Y. [Institute of Applied Mechanics, National Taiwan University, Taipei 106 (China); Law, C.K. [Department of Mechanical and Aerospace Engineering, Princeton University, Princeton, NJ 08544 (United States)

2008-04-15

392

Elucidating alkane adsorption in sodium-exchanged zeolites from molecular simulations to empirical equations  

NASA Astrophysics Data System (ADS)

Configurational-bias Monte Carlo (CBMC) simulations provide adsorption isotherms, Henry coefficients and heats of adsorption of linear alkanes in sodium-exchanged MFI- and FAU-type zeolites. These simulations were carried out using our newly developed force field that reproduces experimental sodium positions in the dehydrated zeolites, and successfully predicts alkane adsorption properties over a wide range of sodium cation densities, temperatures, and pressures. We derived empirical expressions from the simulation data to describe the adsorption of linear alkanes in MFI- and FAU-type zeolites. These expressions afford a suitable substitute for complex CBMC simulations. In the low coverage regime we provide simple expressions that adequately describe the Henry coefficient and adsorption enthalpy of n-alkanes as a function of sodium density and temperature. The predicted Henry coefficients and heats of adsorption compare extremely well to available experimental data. In the high coverage regime we provide an expression for saturation capacities of linear alkanes in the zeolite. This expression, combined with the expression for the Henry coefficients, provides of the complete adsorption isotherms of pure adsorbents and mixtures, in good agreement with the adsorption isotherms obtained from CBMC.

García-Pérez, E.; Torréns, I. M.; Lago, S.; Dubbeldam, D.; Vlugt, T. J. H.; Maesen, T. L. M.; Smit, B.; Krishna, R.; Calero, S.

2005-10-01

393

Variability of n-alkanes and nonacosan-10-ol in natural populations of Picea omorika.  

PubMed

This is the first report of population variability of the contents of n-alkanes and nonacosan-10-ol in the needle epicuticular waxes of Serbian spruce (Picea omorika). The hexane extracts of needle samples originated from three natural populations in Serbia (Vranjak, Zmajeva?ki potok, and Mileševka Canyon) were investigated by GC and GC/MS analyses. The amount of nonacosan-10-ol varied individually from 50.05 to 74.42% (65.74% in average), but the differences between the three investigated populations were not statistically confirmed. The results exhibited variability of the composition of n-alkanes in the epicuticular waxes with their size ranging from C(18) to C(35). The most abundant n-alkanes were C(29), C(31), and C(27) (35.22, 13.77, and 12.28% in average, resp.). The carbon preference index of all the n-alkanes (CPI(total)) of the P. omorika populations (average of populations I-III) ranged from 3.3 to 11.5 (mean of 5.9), while the average chain length (ACL) ranged from 26.6 to 29.2. The principal component and cluster analyses of the contents of nine n-alkanes showed the greatest difference for the population growing in the Mileševka Canyon. The obtained results were compared with previous literature data given for other Picea species, and this comparison was briefly discussed. PMID:23495163

Nikoli?, Biljana; Teševi?, Vele; Ðor?evi?, Iris; Todosijevi?, Marina; Jadranin, Milka; Bojovi?, Srdjan; Marin, Petar D

2013-03-01

394

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

395

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

PubMed

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

396

Role of vapor-phase mass transport during the spreading of a long-chain alkane drop.  

PubMed

The spreading of liquid alkanes over solid surfaces has important applications in painting, coatings, lubrication, and petroleum tertiary recovery. The role of the vapor-phase mass transport accompanying liquid spreading has not been well studied because it is difficult to separate the contributions from the liquid spreading and the vapor-phase transport that occurred at the same time. We used the engineered surface patterns to study the vapor-phase mass transport during liquid spreading. First, we fabricated several hydrophilic, carboxylic acid-terminated patterns (OTSpd) on a hydrophobic, methyl-terminated octadecyltrichlorosilane (OTS) surface. These OTSpd patterns did not connect to each other. Next, we let an alkane drop spread within one OTSpd pattern. The liquid alkane could not spread to other OTSpd patterns because OTS separated them; however, the alkane molecules in the vapor phase could migrate and adsorb on other OTSpd patterns. Therefore, the contributions from the liquid spreading and the vapor-phase transport were separated and could be investigated independently. We found that during the spreading of the liquid alkane, mass transport through the vapor phase cannot be ignored. Alkane molecules adsorbed on the OTSpd surface with their backbones parallel to the surface in the first few layers. Additional alkane molecules adsorbed on these parallel layers to form the seaweed-shaped layers in which the alkane molecules stood up. Our study showed that the parallel layers formed from the vapor-phase mass transport before the liquid alkane spread. Therefore, the liquid alkane does not spread over the more strongly binding OTSpd surface. It actually spreads over the parallel alkane layer, which formed from its own vapor. PMID:19580290

Lu, Lingbo; Cai, Yuguang

2009-12-15

397

Stability of the parallel layer during alkane spreading and the domain structures of the standing-up layer.  

PubMed

The spreading of liquid alkanes over surfaces plays an important role in applications such as lubrication, painting, and printing. To make significant advances in these fields, it is essential to increase our understanding of the interactions between alkanes and surfaces. Long-chain alkanes form two typical adsorption structures on a surface--the parallel phase and the standing-up phase. The most thermodynamically stable structure is the parallel phase, in which the alkane molecules lie flat on the surface. If the temperature is slightly below the bulk melting point, then alkanes form a thermodynamically stable standing-up phase on top of an existing parallel layer. At lower temperatures, the standing-up phase becomes metastable. Using atomic force microscopy, we have found that the standing-up alkane layer consists of multiple domains, indicating that the standing-up layer forms through a multinucleation process during the liquid-solid transition on the surface. If, however, the temperature is above the melting point, then we have found that the standing-up layer shrinks to a droplet and leaves a residue on its original position. During the spreading of an alkane droplet, the parallel layer forms on the substrate surface surrounding the droplet by adsorption from the vapor, which precedes the arrival of the liquid. There has been uncertainty, however, as to whether the parallel layer moves with the liquid alkane or remains stationary during spreading. In this study, we used the residue left on the parallel layer as a landmark to monitor the movement of the parallel layer during the spreading of an alkane droplet. Using this landmark, we found that the parallel layer remained stationary on the substrate, indicating that the liquid alkane spreads on a stationary parallel layer surface. Therefore, this study reveals that the surface properties of the parallel layer--not the surface properties of the substrate--control the spreading and wetting of a liquid alkane. PMID:20297777

Lu, Lingbo; Zander, Kari J; Cai, Yuguang

2010-04-20

398

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

399

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

Radhakrishnan, Krishnan; Whitefield, Philip

1999-01-01

400

www.elsevier.com/locate/jpetscieng Wetting of alkanes on water  

E-print Network

The wetting behavior of oil on water (or brine) has important consequences for the transport properties of oil in watercontaining porous reservoirs, and consequently for oil recovery. The equilibrium wetting behavior of model oils composed of pure alkanes or alkane mixtures on brine is reviewed in this paper. Intermediate between the partial wetting state, in which oil lenses coexist on water with a thin film of adsorbed alkane molecules, and the complete wetting state, in which a macroscopically thick oil layer covers the water, these systems display a third, novel wetting state, in which oil lenses coexist with a mesoscopic (a few-nanometers-thick) oil film. The nature and location of the transitions between these wetting regimes depend on oil and brine compositions, temperature and pressure. D 2002 Elsevier Science B.V. All rigths reserved.

E. Bertr; D. Bonn A; D. Broseta B; H. Dobbs C; J. O. Indekeu C; J. Meunier A; K. Ragil B; N. Shahidzadeh A

401

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

402

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

403

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

404

Pashto Conversation Manual and Pashto Conversation Tapescript.  

ERIC Educational Resources Information Center

This conversation manual and tapescript are part of a set of materials that have been developed to teach oral and written Afghan Pashto to English speakers. In addition to the conversation manual and tapescript, the set consists of a beginning textbook, an intermediate textbook, a reader, and a set of taped lessons that correlate with the…

Tegey, Habibullah; Robson, Barbara

405

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 collection of STM images at room temperature with submolecular resolution, in most cases allowing

Goddard III, William A.

406

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

PubMed

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; Foght, Julia

2014-01-01

407

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

408

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 Araujo e Silva, Renata; Rozycki, Trent; Nesb?, Camilla

2014-01-01

409

The dynamics of the dissociative adsorption of alkanes on Ir(110)  

NASA Astrophysics Data System (ADS)

The dissociative adsorption of C1-C4 alkanes on Ir(110)-(1×2) was investigated using supersonic molecular beam techniques. Three regimes of reactivity were observed. At incident kinetic energies less than 100 kJ/mol the dissociative adsorption probability for propane and butane increased to about 0.6 with both decreasing surface temperature and decreasing translational energy of the incident molecule suggesting that activation occured via trapping of the alkane on the surface. At kinetic energies below 110 kJ/mol for butane, 90 kJ/mol for propane, 60 kJ/mol for ethane, 40 kJ/mol for methane, and at elevated surface temperatures the reaction probabilities for alkanes were independent of surface temperature and translational energy, but increased significantly with the molecular weight or carbon chain length of the incident alkane. This behavior indicates an unactivated reaction channel for each species except methane. At kinetic energies above 110 kJ/mol for butane, 90 kJ/mol for propane, 60 kJ/mol for ethane, and 40 kJ/mol for methane the initial dissociative sticking probability increased with increasing translational energy and was independent of surface temperature, indicating direct translational activation of the incident alkane. The translational energy required to activate the incident alkane via this channel increased with carbon number or molecular weight, indicative of energy transfer processes that dissipate energy in the reactive collision. The dissipative transfer of translational energy out of the reactive channel via a hard cube collision with the surface accounts qualitatively for the increase in the apparent activation barrier with increasing molecular weight in this activated channel.

Hamza, A. V.; Steinruck, H.-P.; Madix, R. J.

1987-06-01

410

Molecular simulation of diffusion of hydrogen, carbon monoxide, and water in heavy n-alkanes.  

PubMed

The self-diffusion and mutual diffusion coefficients of hydrogen (H(2)), carbon monoxide (CO), and water (H(2)O) in n-alkanes were studied by molecular dynamics simulation. n-Alkane molecules were modeled based on the TraPPE united atom force field. NPT molecular dynamics (MD) simulations were performed for n-C(12) to n-C(96) at different temperature and pressure values to validate the accuracy of the force field. In all cases, good agreement was obtained between literature experimental data and model predictions for the density and structure properties of the n-alkanes. Subsequently, the self-diffusion coefficient of the three light components in the various n-alkanes was calculated at different temperatures. Model predictions were in very good agreement with limited experimental data. Furthermore, the Maxwell-Stefan diffusion coefficients of H(2) and CO in two n-alkanes, namely n-C(12) and n-C(28), were calculated based on long MD NVT simulations for different solute concentrations in the n-alkanes. Finally, the Fick diffusion coefficient of the components was calculated as a product of the Maxwell-Stefan diffusion coefficient and a thermodynamic factor. The latter was estimated from the statistical associating fluid theory (SAFT). The Fick diffusion coefficient was found to be higher than the Maxwell-Stefan diffusion coefficient for H(2) and CO in n-C(28). The empirical Darken equation was used to estimate the Maxwell-Stefan diffusion coefficient, and calculations were found to be in good agreement with simulation results. PMID:21254768

Makrodimitri, Zoi A; Unruh, Dominik J M; Economou, Ioannis G

2011-02-17

411

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

412

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

413

PEROXYNITRITE CHEMISTRY  

SciTech Connect

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

Lymar, S.V.

2000-11-29

414

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

415

Regioselective alkane hydroxylation with a mutant CYP153A6 enzyme  

SciTech Connect

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

416

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

SciTech Connect

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

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

1993-10-15

417

Correlation of cocarcinogenic activity among n-alkanes with their physical effects on phospholipid micelles.  

PubMed

N-alkanes from C12 to C28 were tested for their cocarcinogenic or promoting activities to evaluate a correlation of their biologic activity with their effects on transport properties of phospholipid micelles. On this basis, we had predicted that the C18 and C20 homologues would be more active than the better known dodecane. The C12, C16, C18, and C20 n-alkanes, at various dilutions from 6 to 40% by volume in decahydronaphthalene (Decalin), were tested for their relative activity in a cocarcinogenic relationship to benzo[a]pyrene. At a 20% alkane concentration level, the solutions containing octadecane and eicosane induced tumors most rapidly. A 40% dodecane concentration was required to produce this level of cocarcinogenic activity. The activity of octadecane paralleled its physical effects on transport kinetics closely in the 6-40% (by volume) concentration. The C18, C20, and C28 n-alkanes and the C30 olefin squalene at dilutions from 10 to 40% in Decalin (by volume) were tested for their relative promoting activity after a single application of 7,12-dimethylbenz[a]anthracene in benzene. At comparable mole fractions in Decalin, the three n-alkanes had essentially the same promoting activity; squalene, at 20%, showed only borderline activity. Thus the high biologic activity of the C18, C20, and C28 n-alkanes correlated well with their physical effects on the structure of phospholipid micelles (chain-chain interactions of the alkanes with the acyl chains of the lipid). This correlation was interpreted as a strong indication that the liquid crystalline region of the phospholipid assembly (adjacent to the aqueous interface) in the membranes of latent (initiated) cancer cells was the site of action of hydrocarbon cocarcinogens. Application of a modified physical model to pristane, a branched-chain C19 alkane from coal and Colorado shale, indicated higher cocarcinogenic activity than that of n-C18H38. Applied to purified samples of docosane and tetracosane, activity comparable to that of octadecane was indicated. PMID:815559

Horton, A W; Eshleman, D N; Schuff, A R; Perman, W H

1976-02-01

418

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.

419

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.

420

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.

421

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

422

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.

423

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.

424

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

425

Why chemistry? Chemistry is fundamental: it is the enabling  

E-print Network

Chemistry Why chemistry? Chemistry is fundamental: it is the enabling science that underlies many technology. A chemistry degree gives you the understanding to contribute to our future in very topical areas) in Chemistry BSc (Hons) in Chemistry MChem (Hons) in Chemistry (with an industrial placement year) MChem (Hons

Sussex, University of

426

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

PubMed

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

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

2012-11-28

427

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

428

Molecular simulation and macroscopic modeling of the diffusion of hydrogen, carbon monoxide and water in heavy n-alkane mixtures.  

PubMed

The self-diffusion coefficient of hydrogen (H(2)), carbon monoxide (CO) and water (H(2)O) in n-alkanes was studied by molecular dynamics simulation. Diffusion in a few pure n-alkanes (namely n-C(8), n-C(20), n-C(64) and n-C(96)) was examined. In addition, binary n-C(12)-n-C(96) mixtures with various compositions as well as more realistic five- and six-n-alkane component mixtures were simulated. In all cases, the TraPPE united atom force field was used for the n-alkane molecules. The force field for the mixture of n-alkanes was initially validated against experimental density values and was shown to be accurate. Moreover, macroscopic correlations for predicting diffusion coefficient of H(2), CO and H(2)O in n-alkanes and mixtures of n-alkanes were developed. The functional form of the correlation was based on the rough hard sphere theory (RHS). The correlation was applied to simulation data and an absolute average deviation (AAD) of 5.8% for pure n-alkanes and 3.4% for n-alkane mixtures was obtained. Correlation parameters vary in a systematic way with carbon number and so they can be used to provide predictions in the absence of any experimental or molecular simulation data. Finally, in order to reduce the number of adjustable parameters, for the n-alkane mixtures the "pseudo-carbon number" approach was used. This approach resulted in relatively higher deviation from MD simulation data (AAD of 18.2%); however, it provides a convenient and fast method to predict diffusion coefficients. The correlations developed here are expected to be useful for engineering calculations related to the design of the Gas-to-Liquid process. PMID:22354458

Makrodimitri, Zoi A; Unruh, Dominik J M; Economou, Ioannis G

2012-03-28

429

Changes in iso- and n-alkane distribution during biodegradation of crude oil under nitrate and sulphate reducing conditions.  

PubMed

Crude oil consists of a large number of hydrocarbons with different susceptibility to microbial degradation. The influence of hydrocarbon structure and molecular weight on hydrocarbon biodegradation under anaerobic conditions is not fully explored. In this study oxygen, nitrate and sulphate served as terminal electron acceptors (TEAs) for the microbial degradation of a paraffin-rich crude oil in a freshly contaminated soil. During 185 days of incubation, alkanes from n-C11 to n-C39, three n- to iso-alkane ratios commonly used as weathering indicators and the unresolved complex mixture (UCM) were quantified and statistically analyzed. The use of different TEAs for hydrocarbon degradation resulted in dissimilar degradative patterns for n- and iso-alkanes. While n-alkane biodegradation followed well-established patterns under aerobic conditions, lower molecular weight alkanes were found to be more recalcitrant than mid- to high-molecular weight alkanes under nitrate-reducing conditions. Biodegradation with sulphate as the TEA was most pronounced for long-chain (n-C32 to n-C39) alkanes. The observation of increasing ratios of n-C17 to pristane and of n-C18 to phytane provides first evidence of the preferential degradation of branched over normal alkanes under sulphate reducing conditions. The formation of distinctly different n- and iso-alkane biodegradation fingerprints under different electron accepting conditions may be used to assess the occurrence of specific degradation processes at a contaminated site. The use of n- to iso-alkane ratios for this purpose may require adjustment if applied for anaerobic sites. PMID:22001845

Hasinger, Marion; Scherr, Kerstin E; Lundaa, Tserennyam; Bräuer, Leopold; Zach, Clemens; Loibner, Andreas Paul

2012-02-20

430

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

431

Phase equilibria for binary n-alkanenitrile- n-alkane mixtures. III. Vapour-liquid phase equilibria for propanenitrile with C 5?C 8 n-alkanes  

Microsoft Academic Search

Vapour-liquid phase equilibria at 313.15 K for the four mixtures of propanenitrile with n-pentane, n-hexane, n-heptane and n-octane have been determined by the measurement of the total vapour pressure in a static apparatus. All mixtures display azeotropy, with the alkane mole fraction of the azeotrope moving from 0.938 in the C5 mixture to 0.239 for the C8 mixture. The excess

Ian A. McLure; Jose-Luis Arriaga-Colina; David A. Armitage

1997-01-01

432

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

433

Chemistry Rocks: Redox Chemistry as a Geologic Tool.  

ERIC Educational Resources Information Center

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

Burns, Mary Sue

2001-01-01

434

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

435

Conversation and Coordinative Structures  

Microsoft Academic Search

People coordinate body postures and gaze patterns during conversation. We review literature showing that (1) action embodies cognition, (2) postural coordination emerges spontaneously when two people converse, (3) gaze patterns influence postural coordination, (4) gaze coordination is a function of common ground knowledge and visual information that conversants believe they share, and (5) gaze coordination is causally related to mutual

Kevin Shockley; Daniel C. Richardson; Rick Dalec

2009-01-01

436

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.

437

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 ...

438

CHEMISTRY IN EVAPORATING ICES-UNEXPLORED TERRITORY  

SciTech Connect

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

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

2010-12-20

439

Sources and Significance of Alkane and PAH Hydrocarbons in Canadian Arctic Rivers  

Microsoft Academic Search

Hydrocarbon measurements have been made on dissolved, suspended particulate and sediment samples collected in 1987, 1993 and 1994 from the Mackenzie River delta and shelf and in 1993 from 10 smaller Northwest Territories and Nunavut rivers that drain into the Canadian Archipelago or Hudson's Bay. Suspended particulate samples from all rivers have a resolved higher alkane pattern with a well-defined

M. B. Yunker; S. M. Backus; E. Graf Pannatier; D. S. Jeffries; R. W. Macdonald

2002-01-01

440

A Microporous MetalOrganic Framework for Gas Chromatographic Separation of Alkanes  

Microsoft Academic Search

A zinc-based metal-organic framework (MOF) can be transformed reversibly from an open (a) to a dense (b) configuration. The microporous solid is the first example of a MOF that is highly selective in the gas-chromatographic separation of alkanes.

Banglin Chen; Chengdu Liang; Jun Yang; Damacio S. Contreras; Yvette L. Clancy; Emil B. Lobkovsky; Omar M. Yaghi; Sheng Dai

2006-01-01

441

Development of microbodies in Candida tropicalis during incubation in a n -alkane medium  

Microsoft Academic Search

Development of microbodies in Candida tropicalis pK 233 was studied mainly by electron microscopical observation. The yeast cells, precultured on malt extract, scarcely contained microbodies and showed very low catalase activity. When the precultured cells were transferred to a n-alkane medium and incubated with shaking, the number of microbodies increased and concomitantly the activity of catalase was enhanced. That is,

Masako Osumi; Fusako Fukuzumi; Yutaka Teranishi; Atsuo Tanaka; Saburo Fukui

1975-01-01

442

Alkyl nitrate formation from the atmospheric photoxidation of alkanes; a revised estimation method  

Microsoft Academic Search

The available experimental data concerning the yields of alkyl nitrates in the reactions of alkyl peroxy radicals with NO have been used to derive a revised expression for the estimation of alkyl nitrate yields in the atmospheric photooxidation of alkanes as a function of temperature and pressure. This revised expression gives more reasonable predictions of alkyl nitrate yields under high

William P. L. Carter; Roger Atkinson

1989-01-01

443

A Microporous Metal-Organic Framework for Gas Chromatographic Separation of Alkanes  

SciTech Connect

A zinc-based metal-organic framework (MOF) can be transformed reversibly from an open (a) to a dense (b) configuration. The microporous solid is the first example of a MOF that is highly selective in the gas-chromatographic separation of alkanes.

Chen, Banglin [ORNL; Liang, Chengdu [ORNL; Yang, Jun [University of Michigan; Contreras, Damacio [University of Texas; Clancy, Yvette [University of Texas; Lobkovsky, Emil B. [Cornell University; Yaghi, Omar [University of Michigan; Dai, Sheng [ORNL

2006-01-01

444

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

E-print Network

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

Radhashree Maitra; Cristina C. Clement; Giovanna M. Crisi; Neil Cobelli; Laura Santambrogio

2008-01-01

445

Di-tert-butyl Peroxide-Promoted ?-Alkylation of ?-Amino Carbonyl Compounds by Simple Alkanes.  

PubMed

A di-tert butyl peroxide (DTBP)-promoted ?-alkylation of ?-amino carbonyl compounds by simple alkanes is developed, proceeding through dual sp(3) C-H bonds cleavage. The reaction was applicable for ?-amino ketones and ?-amino esters, providing a facile pathway for the ?-functionalization of these substrates. The radical pathway is involved in this transformation. PMID:25243610

Peng, Haibo; Yu, Jin-Tao; Jiang, Yan; Yang, Haitao; Cheng, Jiang

2014-10-17

446

Progressive compression of 1,?-diammonium-alkanes inside a rigid crystalline molecular cage.  

PubMed

We present herein the compression mechanisms of linear 1,?-diammonium-alkanes, confined within a molecular cage self-assembled in water. The exact coiling behaviour is determined from atomic resolution X-ray diffraction and shows crenel-like conformations in the compressed states. PMID:24970018

Dumitrescu, Dan; Legrand, Yves-Marie; Petit, Eddy; van der Lee, Arie; Barboiu, Mihail

2014-10-21

447

Enthalpy and entropy of transfer of alkanes from water phase to the micelle core  

Microsoft Academic Search

Enthalpy and entropy of transfer from water phase to a sodium dodecyl sulphate (SDS) micelle core and , respectively, have been investigated by molecular dynamics calculation for a series of hydrophobic solutes originally immiscible with water. It is found that both thermodynamic quantities decrease as a function of number of carbon atoms of the alkanes. Structural behaviour of the solubilised

K. Fujimoto; N. Yoshii; S. Okazaki

2012-01-01

448

Enthalpy and entropy of transfer of alkanes from water phase to the micelle core  

Microsoft Academic Search

Enthalpy and entropy of transfer from water phase to a sodium dodecyl sulphate (SDS) micelle core and , respectively, have been investigated by molecular dynamics calculation for a series of hydrophobic solutes originally immiscible with water. It is found that both thermodynamic quantities decrease as a function of number of carbon atoms of the alkanes. Structural behaviour of the solubilised

K. Fujimoto; N. Yoshii; S. Okazaki

2011-01-01

449

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

Microsoft Academic Search

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

S. Afsharypuor; G. B. Lockwood

1985-01-01

450

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

Microsoft Academic Search

In this study we examined breath volatile hydrocarbon concentrations in exhaled air of hemodialysis patients. We assessed both C2–C5 alkanes – among them ethane and pentane the production of which in man is essentially due to the action free radicals exert on polyunsaturated fatty acids – and isoprene, an unsaturated hydrocarbon the biosynthesis and biological effects of which are the

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

1999-01-01

451

Gas-phase reactions of LaFe/sup +/ with alkanes  

SciTech Connect

The formation and reactions of LaFe/sup +/ with saturated hydrocarbons are reported. Laser-generated La/sup +/ reacts with iron pentacarbonyl to yield predominantly LaFe(CO)/sub 3//sup +/, which upon collisional activation yields LaFe/sup +/. The reactions of LaFe/sup +/ with alkanes are quite different from that of either La/sup +/ or Fe/sup +/. Dehydrogenation is common for the reactions of LaFe/sup +/ with alkanes. Dehydrogenation and methane elimination are observed for the reaction of neopentane with LaFe/sup +/. Carbon-carbon cleavage and dehydrogenation occur in the reactions of LaFe/sup +/ with C/sub 3/ and C/sub 4/ cyclic alkanes, while dehydrogenation is observed exclusively for cyclopentane, cyclohexane, and methylcyclohexane. The reactivity of LaFe/sup +/ is particularly interesting in that several other heterodinuclear ions have been observed to be unreactive with alkanes, although their constituent monoatomic ions are reactive. D/sup 0/(La/sup +/Fe) was determined to be 48 +/- 5 kcal/mol by photodissociation.

Huang, Y.; Freiser, B.S.

1988-01-20

452

Compilation of Kinetic Parameters for the Thermal Degradation of n-Alkane Molecules.  

National Technical Information Service (NTIS)

A list of several hundred free-radical reactions which occur during the low temperature (700-850 K) pyrolysis of small n-alkane molecules has been assembled and a set of reliable, self-consistent Arrhenius rate parameters has been assigned on the basis of...

D. L. Allara, R. Shaw

1980-01-01

453

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 of contempor- ary catalysis is the controlled oxidation of hydrocar- bons.[1] Processes for controlled, stereo- and regioselective oxidation of hydrocarbon feed stocks to more valuable and useful products such as alco- hols

Arnold, Frances H.

454

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 June 2010 Accepted 29 June 2010 Available online 10 August 2010 Keywords: Pt bimetallic catalyst Mg(Ga)(Al)O support STEM EXAFS Dehydrogenation a b s t r a c t A novel approach is described for preparing Ga

Bell, Alexis

455

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

PubMed Central

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

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

2008-01-01

456

Cloning and expression of alkane hydroxylase-1 from Alcanivorax borkumensis in Escherichia coli.  

PubMed

Enzymes with hydroxylating activity on alkanes have potential application as biotransformation catalysts in chemical and pharmaceutical industry. Genome of Alcanivorax borkumensis, a marine bacterium with hydrocarbon dissimilation activity, contains at least two P450 monooxygenases and two nonheme monooxygenases, AlkB1 and AlkB2, respectively. Presumably, all these enzymes possess alkane hydroxylating activity. Both AlkB1 and AlkB2 are membrane proteins. Two accessory proteins, rubredoxin and rubredoxin reductase, supply the reducing equivalent from nicotinamide adenine dinucleotide phosphate reduced (NADPH to hydroxylases. Rubredoxin reductase catalyses the reduction of rubredoxin by oxidation of NADPH, and rubredoxin transfers the electrons to the alkane hydroxylase to complete the hydroxylation reaction. Here, we sought to investigate the expression of alkB1 gene in Escherichia coli. Therefore, we amplified alkB1 gene from A. borkumensis genome by polymerase chain reaction and cloned it in the expression vector pET26 upstream of His-tag sequence. Predisposed BL21 (DE3) cells were transformed by the recombinant vector. At last, expression of recombinant enzyme was confirmed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis and Western blotting. Regarding the potential ability of this enzyme in hydroxylation of long-chained alkanes, the application of it would be studied in petroleum downstream industries. PMID:22064680

Eidani, Simin Zadehgan; Shahraki, Mahvash Khodabandeh; Gasemisakha, Fatemeh; Hahsemi, Mehrdad; Bambai, Bijan

2012-07-01

457

The benzoyl peroxide-promoted functionalization of simple alkanes with 2-aryl phenyl isonitrile.  

PubMed

The benzoyl peroxide (BPO)-promoted phenanthridinylation of simple alkanes with isonitrile is developed via C(sp(3))-H and C(sp(2))-H bond cleavage. This procedure is featured by dual C-C bond formation proceeding with the addition of an alkyl radical to isonitrile followed by radical aromatic cyclization. PMID:24993445

Sha, Wanxing; Yu, Jin-Tao; Jiang, Yan; Yang, Haitao; Cheng, Jiang

2014-08-21

458

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

SciTech Connect

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

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

1998-07-15

459

Electron Microscopy in the Catalysis of Alkane Oxidation, Environmental Control, and Alternative Energy Sources  

Microsoft Academic Search

The key role of electron microscopy in understanding and creating advanced catalyst materials and processes in selective alkane oxidation, environmental control, and alternative energy sources is reviewed. In many technological processes, catalysts are increasingly nanoscale heterogeneous materials. With growing regulatory guidelines requiring efficient and environmentally compatible catalytic processes, it is crucial to have a fundamental understanding of the catalyst nanostructure

Pratibha L. Gai; Jose J. Calvino

2005-01-01

460

Chem 350 Jasperse Ch. 3 Handouts 1 ALKANE NAMES (Memorize) (Sections 3.2)  

E-print Network

Industrial Alkanes (Sections 3.5) Name # C's Boiling Range Use Natural Gas C1-C3 (70% methane) Gas Fuel "Petroleum Gas" C2-C4 Heating, Gas Propane C3 -42º Propane tanks, camping, etc. Gasoline C4-C9 30-180º

Jasperse, Craig P.

461

Georgia Tech Chemistry & Biochemistrywww.chemistry.gatech.edu/rig --Research  

E-print Network

Georgia Tech Chemistry & Biochemistrywww.chemistry.gatech.edu/rig -- Research New Faculty Workshop.aip.org ! #12;Georgia Tech Chemistry & Biochemistrywww.chemistry.gatech.edu/rig -- Research New Faculty Workshop

Feig, Andrew

462

Conversion of hydrocarbons to biosurfactants : an insight into the bioprocess optimisation of biosurfactant production using alkanes as inducers.  

E-print Network

??Includes abstract. Surfactants are chemical compounds that are able to alter interfacial properties, particularly surface tension. When they are biologically produced, the term biosurfactant is… (more)

Bamara, Prosper.

2009-01-01

463

Composition research of n-alkanes in hydrothermal systems of Mid-Atlantic Ridge by method gas chromatography/ mass spectrometry  

NASA Astrophysics Data System (ADS)

The composition of n-alkanes in hydrothermal formations was studied in hydrothermal fields of several zones of Mid-Atlantic Ridge. The samples for investigation were collected on cruise 50 of R/V Akademik Mstislav Keldysh by Mir-1 and Mir-2 manned submersibles (Shirshov Institute of Oceanology, RAS). Molecular and group compositions of n-alkanes were analyzed in sulfide and carbonate deposits of hydrothermal fields in Mid-Atlantic Ridge (Rainbow, Lost City, Broken Spur) related with ultrabasic rocks in oceanic core and basalt volcanism. As a result of experiments it was devised procedures of detected and research n-alkanes in hydrothermal deposits using gas chromatography-mass spectrometry (GC/MS) method. Detection limit of n-alkanes by using this procedure formed 3×10^(-9) - 10^(-8) % depending on the component. It was shown a presence of n-alkanes C15-C32 in most explored samples of hydrothermal deposits. Total n-alkanes concentrations in the samples from Mid-Atlantic Ridge are low and vary widely from 0,02 to 0,038 µg/g of dry weight of ore deposits. These differences can be explained by different conditions of ore deposit formation (pressure, temperature), different mineralogical composition of ore deposits, and possibly by some others. Analysis of sulfide samples from the Broken Spur showed presence of n-alkanes biogenic and abiogenic-thermocatalytic nature in equal amount. It was concluded that the composition of n-alkanes in hydrothermal deposits from the Lost City hydrothermal field is influenced by two prevailing processes of organic matter transformation - microbial and thermocatalytic transformation. In hydrothermal deposits from the Rainbow field it was revealed abiogenic-thermocatalytic nature of n-alkanes predominantly.

Shulga, N. A.; Peresypkin, V. I.; Revelsky, I. A.

2009-04-01

464

Igniting Chemistry in Fireworks  

NSDL National Science Digital Library

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

Foundation, Wgbh E.

2004-01-29

465

Computational Chemistry Robots  

E-print Network

Computational Chemistry Robots ACS Sep 2005 Computational Chemistry Robots J. A. Townsend, P. Murray-Rust, S. M. Tyrrell, Y. Zhang jat45@cam.ac.uk Can high-throughput computation provide a reliable “experimental” resource for molecular...

Townsend, Joseph A; Murray-Rust, Peter; Tyrrell, Simon M; Zhang, Yong

466

Environmental chemistry: Volume A  

SciTech Connect

This is an extensive introduction to environmental chemistry for engineering and chemical professionals. The contents of Volume A include a brief review of basic chemistry prior to coverage of litho, atmo, hydro, pedo, and biospheres.

Yen, T.F.

1999-08-01

467

Organometallic Chemistry of Molybdenum.  

ERIC Educational Resources Information Center

Suggests ways to avoid some of the problems students have learning the principles of organometallic chemistry. Provides a description of an experiment used in a third-year college chemistry laboratory on molybdenum. (TW)

Lucas, C. Robert; Walsh, Kelly A.

1987-01-01

468

An Introduction to Chemistry: Nuclear Chemistry  

NSDL National Science Digital Library

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

Bishop, Mark

469

The Chemistry Hypermedia Project  

NSDL National Science Digital Library

These materials and documents are typical of those presented in an undergraduate course in general chemistry, analytical chemistry, and analytical instrumentation. Resources for educators include Excel spreadsheet simulations for analytical and physical chemistry, prototype JavaScripts and PERL scripts, lists of web workshops and publications, and links to the most recent papers and presentations from the Chemistry Hypermedia Project. There are also tutorials for equilibrium practice problems and analytical spectroscopy.

470

Smectite to Illite Conversion Rates: Effects of Solution Chemistry  

Microsoft Academic Search

Mixed-layer illite\\/smectite (I\\/S) was formed by reacting the Chambers or Polkville montmoril- lonite hydrothermally at 270 ~ and 350~ from several hours to more than 15 weeks. Reactions were con- ducted in closed vessels containing K or mixed K-Na, K-Ca, or K-Mg solutions of varying concentrations. The reaction rate and the rate of ordering of I\\/S for the reaction smectite

Herman E. Roberson; RICHARD W. LAHANN

1981-01-01

471

Pretreatment of lignocellulosic biomass using Fenton chemistry.  

PubMed

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

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

2014-06-01

472

Why chemistry? Chemistry is fundamental: it is the enabling science  

E-print Network

Chemistry Why chemistry? Chemistry is fundamental: it is the enabling science that underlies many technology. A chemistry degree allows you to understand and to contribute to our future. Chemistry is challenging: understanding the very fabric of matter is both stimulating and rewarding. Studying chemistry

Sussex, University of

473

Chemistry Division Department of Biological  

E-print Network

1 Chemistry Division Department of Biological and Chemical Sciences, Illinois Institute-13 Chemistry Division invites nominations for Kilpatrick Fellowship for the academic year 2012's Chemistry Department from 1947­1960. Mary Kilpatrick was a chemistry faculty member from 1947

Heller, Barbara

474

Microwaves and Chemistry: The Catalysis of an Exciting Marriage  

E-print Network

MICROWAVES AND CHEMISTRY: THE CATALYSIS OF AN EXCITING MARRIAGE JEFF WAN, PROFESSOR OF CHEMISTRY, QUEEN'S UNIVERSITY, KINGSTON, CANADA ABSTRACT The potential of microwave power as a tool to facilitate chemical reactions has not whetted... personal advice and support by a number of major industry is gratefully acknowledged. REFERENCES 1. 1.K.S. Wan, "Conversion of methane to ethylene and hydrogen", US Patent 4 574 038, 1986. 2. 1. Wan, M. Tse, H. Husby and M. Depew, "High Power pulsed...

Wan, J.

475

Adam Benoit Medicinal Chemistry  

E-print Network

#12;Adam Benoit Medicinal Chemistry Ph.D. Thesis Title: Synthesis and Evaluation of Acridine Country: United States #12;Amit Gangar Medicinal Chemistry Ph.D. Thesis Title: Design and Development Wagner Home Country: India #12;Dan Wang Medicinal Chemistry M.S. Thesis Title: Synthesis and Evaluation

Thomas, David D.

476

A chronicler of chemistry  

NASA Astrophysics Data System (ADS)

Thomas Hager, author of popular science books that revisit some of the most significant developments in chemistry over the past century, talks to Nature Chemistry about the challenges of writing for a general audience, and how his dislike of chemistry was turned around by a fellow Oregonian of considerable repute.

2012-04-01

477

Green Chemistry and Education.  

ERIC Educational Resources Information Center

Many students today are profoundly interested in the sustainability of their world. Introduces Green Chemistry and its principles with teaching materials. Green Chemistry is the use of chemistry for pollution prevention and the design of chemical products and processes that are environmentally benign. (ASK)

Hjeresen, Dennis L.; Schutt, David L.; Boese, Janet M.

2000-01-01

478

Chemistry and Art.  

ERIC Educational Resources Information Center

Describes a Chemistry and Art project developed for secondary students and teachers sponsored by the National Gallery and The Royal Society of Chemistry in the United Kingdom. Discusses aspects of the techniques used in creating five paintings as well as the chemistry involved in their making, deterioration, conservation, and restoration.…

Berry, Martyn

1999-01-01

479

Environmental Chemistry Activities.  

ERIC Educational Resources Information Center

The authors of this curriculum supplement believe in a laboratory approach to chemistry and express the feeling that environmental chemistry provides the students an opportunity to apply theoretical chemistry to important practical problems. There are eighteen activities presented, each accompanied with behavioral objectives, one or more suggested…

Jackland, Thomas; And Others

480

Engineering Materials and Chemistry  

E-print Network

................................................................................................. 10 #12;3 Course staff Dr John Daniels (Materials) Course Coordinator & Lecturer Room 217, School: by appointment A/Prof Stephen Colbran (Chemistry) Lecturer Room 225 Dalton Building (F12) Phone: 9385 4737 s: by appointment Ms Anne Ayres (Chemistry) Chemistry Tutorial and Laboratory Administrator Room 105 Dalton Building

New South Wales, University of