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The Journal of Physical Chemistry. B Feb 2022Paraffin wax deposition has long been a vexing problem in industry. Especially, in offshore oil production, paraffin wax deposits and clogs pipes and containers because...
Paraffin wax deposition has long been a vexing problem in industry. Especially, in offshore oil production, paraffin wax deposits and clogs pipes and containers because of low temperature, causing severe economic loss. It has been known that the crystallization of n-alkanes mainly causes the deposition of paraffin wax, which is necessary to understand the mechanism of the crystallization behavior of paraffin wax. We solve the challenge of describing the crystallization behavior of the alkane mixture system and evaluate the contributions of every carbon atom to crystallization based on the occupied volume, structure entropy, and order parameter. These results demonstrate that the middle atoms are the main contributor to crystallization, and the end atoms of n-alkanes are unfavorable for the crystallization of n-alkanes, showing that increasing the number of end atoms, for example, adding branched alkanes, will hinder the crystallization of paraffin wax. Furthermore, perhydrosqualene is chosen to study the inhibition of crystallization by adding branched alkanes. As there are different properties between the end and the middle atoms, based on the principle of dissolution with similar properties, a small number of branched alkanes will promote crystallization. Also, an inhibitory effect of the end atoms is observed when the proportion of branched alkanes increases to a certain percentage. Our simulation work describes the crystallization behavior of paraffin wax in detail, providing theoretical assistance for preventing and controlling paraffin deposition.
Topics: Alkanes; Carbon; Crystallization; Paraffin; Waxes
PubMed: 35077173
DOI: 10.1021/acs.jpcb.1c10000 -
Journal of Bacteriology Aug 1975In vitro complementation assays have been used to demonstrate the induction of alkane hydroxylase proteins in mutants lacking the ability to convert n-alkanes to their...
In vitro complementation assays have been used to demonstrate the induction of alkane hydroxylase proteins in mutants lacking the ability to convert n-alkanes to their primary alcohols. Purified heptane is an effective inducer in a mutant lacking detectable hydroxylase activity.
Topics: Alkanes; Bacterial Proteins; Enzyme Induction; Genes; Mixed Function Oxygenases; Mutation; Plasmids; Pseudomonas
PubMed: 1150630
DOI: 10.1128/jb.123.2.759-760.1975 -
ChemSusChem Dec 2013Combo deal: Biomass furaldehydes are upgraded into oxygenated diesel and high-quality C10-12 linear alkane fuels. The first of two steps involves solvent-free...
Combo deal: Biomass furaldehydes are upgraded into oxygenated diesel and high-quality C10-12 linear alkane fuels. The first of two steps involves solvent-free self-condensation (Umpolung) through organocatalysis using an N-heterocyclic carbene (NHC), yielding C10 -C12 furoin intermediates. In the metal-acid tandem catalysis step, in water, the furoin intermediates are converted into oxygenated biodiesel by hydrogenation, etherification or esterification; or into premium alkane jet fuels by hydrodeoxygenation.
Topics: Acids; Alkanes; Biofuels; Biomass; Catalysis; Esterification; Furaldehyde; Hydrogenation; Metals
PubMed: 23939751
DOI: 10.1002/cssc.201300476 -
ACS Nano Sep 2009Size and ligand effects are the basis for the novel properties and applications of metallic nanoparticles (NPs) in nanoelectronics, optoelectronics, and biotechnology....
Size and ligand effects are the basis for the novel properties and applications of metallic nanoparticles (NPs) in nanoelectronics, optoelectronics, and biotechnology. This work reports the first observation of enhanced photoelectron emission from metallic Au NPs ligated by alkanethiols. The enhancement is based on a conceptually new mechanism: the AuNP provides electrons while the alkane ligand emits electrons due to its low or negative electron affinity. Moreover, the AuNP-ligand chemical bonding is found to significantly facilitate the transmission of photoexcited electrons from the AuNP to the ligand emitter. Consequently the smooth NP film, which is a typical low-aspect-ratio two-dimensional structure, exhibits strong and stable field emission behavior under photoillumination conditions. The photoenhanced field emission is related to the interband and surface plasmon transitions in AuNPs, and a photoenhancement factor of up to approximately 300 is observed for the AuNP-based field emission. This is highly remarkable because field emission is often based on one-dimensional, high-aspect-ratio nanostructures (e.g., nanotubes and nanowires) with geometrical field enhancement effect. The chemical linkage of electron-supplying AuNP and electron-emitting alkane ligand represents a fundamentally new mechanism for efficient photoexcitation and emission. Being low-temperature/solution processable, and inkjet printable, AuNPs may be a flexible material system for optoelectronic applications such as photodetection and photoenhanced field emission.
Topics: Alkanes; Electrons; Gold; Ligands; Metal Nanoparticles; Quantum Theory; Spectrum Analysis; Sulfur
PubMed: 19769404
DOI: 10.1021/nn9005335 -
Marine Pollution Bulletin Aug 2013Petroleum products spill and leakage have become two major environmental challenges in Iran. Sampling was performed in the petroleum reservoir waste water of Tehran and...
Petroleum products spill and leakage have become two major environmental challenges in Iran. Sampling was performed in the petroleum reservoir waste water of Tehran and Kerman Provinces of Iran. Alkane degrading bacteria were isolated by enrichment in a Bushnel-Hass medium, with hexadecane as sole source of carbon and energy. The isolated strains were identified by amplification of 16S rDNA gene and sequencing. Specific primers were used for identification of alkane hydroxylase gene. Fifteen alkane degrading bacteria were isolated and 8 strains were selected as powerful degradative bacteria. These 8 strains relate to Rhodococcus jostii, Stenotrophomonas maltophilia, Achromobacter piechaudii, Tsukamurella tyrosinosolvens, Pseudomonas fluorescens, Rhodococcus erythropolis, Stenotrophomonas maltophilia, Pseudomonas aeruginosa genera. The optimum concentration of hexadecane that allowed high growth was 2.5%. Gas chromatography results show that all strains can degrade approximately half of hexadecane in one week of incubation. All of the strains have alkane hydroxylase gene which are important for biodegradation. As a result, this study indicates that there is a high diversity of degradative bacteria in petroleum reservoir waste water in Iran.
Topics: Alkanes; Bacteria; Base Sequence; Biodegradation, Environmental; Cytochrome P-450 CYP4A; Environmental Monitoring; Iran; Molecular Sequence Data; Petroleum; Wastewater; Water Pollutants, Chemical
PubMed: 23790464
DOI: 10.1016/j.marpolbul.2013.05.002 -
Environmental Science & Technology May 2007As part of the Canadian Atmospheric Fine Particle Research Program to obtain reliable primary source emission profiles, a molecular sieve method was developed to...
As part of the Canadian Atmospheric Fine Particle Research Program to obtain reliable primary source emission profiles, a molecular sieve method was developed to reliably determine n-alkanes in lubricating oils, vehicle emissions, and mobile source dominated ambient particulate matter (PM). This work was also initiated to better calculate carbon preference index values (CPI: the ratio of the sums of odd over even n-alkanes), a parameter for estimating anthropogenic versus biogenic contributions in PM. n-Alkanes in lubricating oil and mobile source dominated PM are difficult to identify and quantify by gas chromatography due to the presence of similar components that cannot be fully resolved. This results in a hump, the unresolved complex mixture (UCM) that leads to incorrect n-alkane concentrations and CPI values. The sieve method yielded better chromatography, unambiguous identification of n-alkanes and allowed examination of differences between n-alkane profiles in light (LDV) and heavy duty vehicle (HDV) lubricating oils that would have been otherwise difficult. These profile differences made it possible to relate the LDV profile to that of the PM samples collected during a tunnel study in August 2001 near Vancouver (British Columbia, Canada). The n-alkane PM data revealed that longer sampling times result in a negative artifact, i.e., the desorption of the more volatile n-alkanes from the filters. Furthermore, the sieve procedure yielded n-alkane data that allowed calculation of accurate CPI values for lubricating oils and PM samples. Finally, this method may prove helpful in estimating the respective diesel and gasoline contributions to ambient PM.
Topics: Alkanes; Chromatography, Gel; Lubrication; Motor Vehicles; Oils; Particulate Matter; Reproducibility of Results; Vehicle Emissions
PubMed: 17547199
DOI: 10.1021/es062233h -
Isotopes in Environmental and Health... 2015During the last decade compound-specific deuterium ((2)H) analysis of plant leaf wax-derived n-alkanes has become a promising and popular tool in paleoclimate research....
Do n-alkane biomarkers in soils/sediments reflect the δ²H isotopic composition of precipitation? A case study from Mt. Kilimanjaro and implications for paleoaltimetry and paleoclimate research.
During the last decade compound-specific deuterium ((2)H) analysis of plant leaf wax-derived n-alkanes has become a promising and popular tool in paleoclimate research. This is based on the widely accepted assumption that n-alkanes in soils and sediments generally reflect δ(2)H of precipitation (δ(2)H(prec)). Recently, several authors suggested that δ(2)H of n-alkanes (δ(2)H(n-alkanes)) can also be used as a proxy in paleoaltimetry studies. Here, we present results from a δ(2)H transect study (∼1500 to 4000 m above sea level [a.s.l.]) carried out on precipitation and soil samples taken from the humid southern slopes of Mt. Kilimanjaro. Contrary to earlier suggestions, a distinct altitude effect in δ(2)H(prec) is present above ∼2000 m a.s.l., that is, δ(2)H(prec) values become more negative with increasing altitude. The compound-specific δ(2)H values of nC27 and nC29 do not confirm this altitudinal trend, but rather become more positive both in the O-layers (organic layers) and the Ah-horizons (mineral topsoils). Although our δ(2)H(n-alkane) results are in agreement with previously published results from the southern slopes of Mt. Kilimanjaro [Peterse F, van der Meer M, Schouten S, Jia G, Ossebaar J, Blokker J, Sinninghe Damsté J. Assessment of soil n-alkane δD and branched tetraether membrane lipid distributions as tools for paleoelevation reconstruction. Biogeosciences. 2009;6:2799-2807], a re-interpretation is required given that the δ(2)H(n-alkane) results do not reflect the δ(2)H(prec) results. The theoretical framework for this re-interpretation is based on the evaporative isotopic enrichment of leaf water associated with the transpiration process. Modelling results show that relative humidity, decreasing considerably along the southern slopes of Mt. Kilimanjaro (from 78% in ∼2000 m a.s.l. to 51% in 4000 m a.s.l.), strongly controls δ(2)H(leaf water). The modelled (2)H leaf water enrichment along the altitudinal transect matches well the measured (2)H leaf water enrichment as assessed by using the δ(2)H(prec) and δ(2)H(n-alkane) results and biosynthetic fractionation during n-alkane biosynthesis in leaves. Given that our results clearly demonstrate that n-alkanes in soils do not simply reflect δ(2)H(prec) but rather δ(2)H(leaf water), we conclude that care has to be taken not to over-interpret δ(2)H(n-alkane) records from soils and sediments when reconstructing δ(2)H of paleoprecipitation. Both in paleoaltimetry and in paleoclimate studies changes in relative humidity and consequently in δ(2)H(n-alkane) values can completely mask altitudinally or climatically controlled changes in δ(2)H(prec).
Topics: Alkanes; Biomarkers; Deuterium; Geologic Sediments; Meteorology; Paleontology; Rain; Soil
PubMed: 26156121
DOI: 10.1080/10256016.2015.1058790 -
Environmental Microbiology Sep 2011Diverse microorganisms have been described to degrade petroleum hydrocarbons anaerobically. Strains able to utilize n-alkanes do not grow with aromatic hydrocarbons,...
Diverse microorganisms have been described to degrade petroleum hydrocarbons anaerobically. Strains able to utilize n-alkanes do not grow with aromatic hydrocarbons, whereas strains able to utilize aromatic hydrocarbons do not grow with n-alkanes. To investigate this specificity in more detail, three anaerobic n-alkane degraders (two denitrifying, one sulfate-reducing) and eight anaerobic alkylbenzene degraders (five denitrifying, three sulfate-reducing) were incubated with mixtures of n-alkanes and toluene. Whereas the toluene degradationers formed only the characteristic toluene-derived benzylsuccinate and benzoate, but no n-alkane-derived metabolites, the n-alkane degraders formed toluene-derived benzylsuccinate, 4-phenylbutanoate, phenylacetate and benzoate besides the regular n-alkane-derived (1-methylalkyl)succinates and methyl-branched alkanoates. The co-metabolic conversion of toluene by anaerobic n-alkane degraders to the level of benzoate obviously follows the anaerobic n-alkane degradation pathway with C-skeleton rearrangement and decarboxylation rather than the β-oxidation pathway of anaerobic toluene metabolism. Hence, petroleum-derived aromatic metabolites detectable in anoxic environments may not be exclusively formed by genuine alkylbenzene degraders. In addition, the hitherto largely unexplored fate of fumarate hydrogen during the activation reactions was examined with (2,3-(2) H(2) )fumarate as co-substrate. Deuterium was completely exchanged with hydrogen at the substituted carbon atom (C-2) of the succinate adducts of n-alkanes, whereas it is retained in toluene-derived benzylsuccinate, regardless of the type of enzyme catalysing the fumarate addition reaction.
Topics: Alkanes; Bacteria, Anaerobic; Biodegradation, Environmental; Fumarates; Succinates; Toluene
PubMed: 21880102
DOI: 10.1111/j.1462-2920.2011.02529.x -
Biochemical and Biophysical Research... Feb 2008The sulfate-reducing strain AK-01 activates alkanes via addition of the subterminal carbon to the double bond of fumarate. This reaction is similar to the action of the...
The sulfate-reducing strain AK-01 activates alkanes via addition of the subterminal carbon to the double bond of fumarate. This reaction is similar to the action of the glycyl radical enzyme benzylsuccinate synthase (Bss). It was hypothesized that strain AK-01 possesses a similar enzyme. Degenerate bssA primers and inverse PCR were used to amplify two unlinked genes (assA1 and assA2), which encode catalytic subunits of glycyl radical type enzymes. Subsequent genome sequencing of AK-01 revealed two ass operons. SDS-PAGE analysis of AK-01 grown on n-hexadecane revealed a 95-kDa protein which is absent in hexadecanoate-grown cells. LC-MS/MS data obtained from a tryptic digest of this protein match the deduced amino acid sequence encoded by assA1, thus confirming AssA1's involvement in alkane metabolism. This report is the first description of a gene involved in anaerobic n-alkane metabolism in a sulfate-reducer and provides evidence for a novel glycyl radical enzyme.
Topics: Alkanes; Amide Synthases; Bacteria, Anaerobic; Base Sequence; Molecular Sequence Data; Species Specificity; Succinic Acid
PubMed: 18053803
DOI: 10.1016/j.bbrc.2007.11.094 -
Microbial Cell Factories Dec 2022The use of biologically produced alkanes has attracted considerable attention as an alternative energy source to petroleum. In 2010, the alkane synthesis pathway in... (Review)
Review
The use of biologically produced alkanes has attracted considerable attention as an alternative energy source to petroleum. In 2010, the alkane synthesis pathway in cyanobacteria was found to include two small globular proteins, acyl-(acyl carrier protein [ACP]) reductase (AAR) and aldehyde deformylating oxygenase (ADO). AAR produces fatty aldehydes from acyl-ACPs/CoAs, which are then converted by ADO to alkanes/alkenes equivalent to diesel oil. This discovery has paved the way for alkane production by genetically modified organisms. Since then, many studies have investigated the reactions catalyzed by AAR and ADO. In this review, we first summarize recent findings on structures and catalytic mechanisms of AAR and ADO. We then outline the mechanism by which AAR and ADO form a complex and efficiently transfer the insoluble aldehyde produced by AAR to ADO. Furthermore, we describe recent advances in protein engineering studies on AAR and ADO to improve the efficiency of alkane production in genetically engineered microorganisms such as Escherichia coli and cyanobacteria. Finally, the role of alkanes in cyanobacteria and future perspectives for bioalkane production using AAR and ADO are discussed. This review provides strategies for improving the production of bioalkanes using AAR and ADO in cyanobacteria for enabling the production of carbon-neutral fuels.
Topics: Cyanobacteria; Oxygenases; Alkanes; Oxidoreductases; Escherichia coli; Aldehydes
PubMed: 36503511
DOI: 10.1186/s12934-022-01981-4