Alkane Chain Length Research Articles

Characterization and genomic analysis of highly efficient thermotolerant oil-degrading bacterium Gordonia sp. 1D

A thermotolerant bacterial strain 1D isolated from refinery oil-contaminated soil was identified as Gordonia sp. based on the analysis of 16S rRNA and gyrB gene sequences. The strain was found to utilize crude oil, diesel fuel, and a wide spectrum of alkanes at temperatures up to 50°C. Strain 1D is the first representative of Gordonia amicalis capable of utilizing alkanes of chain length up to С36 at a temperature of 45-50°C. The degree of crude oil degradation by Gordonia sp. 1D at 45°C was 38% in liquid medium and 40% in soil (with regard to abiotic loss). There are no examples of so effective hydrocarbon-oxidizing thermotolerant Gordonia in the world literature. The 1D genome analysis revealed the presence of two alkane hydroxylase gene clusters, genes of dibenzothiophene cleavage, and the cleavage of salicylate and gentisate-naphthalene metabolism intermediates. The highly efficient thermotolerant strain Gordonia sp. 1D can be used in remediation of oil-contaminated soils in hot climates.

Molecular dynamics simulation of the folding of single alkane chains with different lengths on single-walled carbon nanotubes and graphene.

Chain folding is an important step during polymer crystallization. In order to study the effects of the surface on chain folding, molecular dynamics simulations of the folding of different alkane chains on three kinds of single-walled carbon nanotubes (SWCNTs) and graphene were performed. The folding behaviors of the single alkane chains on these surfaces were found to be different from their folding behaviors in vacuum. The end-to-end distances of the chains were calculated to explore the chain folding. An increasing tendency to fold into two or more stems with increasing alkane chain length was observed. This result indicates that the occurrence and the stability of chain folding are related to the surface curvature, the diameter of the SWCNT, and surface texture. In addition, the angle between the direction of the alkane chain segment and the direction of the surface texture was measured on different surfaces.

Regenerative Core-Shell Nanoparticles for Simultaneous Removal and Detection of Endotoxins.

Detection and removal of lipopolysaccharides (LPS) from food and pharmaceutical preparations is important for their safe intake and administration to avoid septic shock. We have developed an abiotic system for reversible capture, removal, and detection of LPS in aqueous solutions. Our system comprises long C18 acyl chains tethered to Fe3O4/Au/Fe3O4 nanoflowers (NFs) that act as solid supports during the separation process. The reversible LPS binding is mediated by facile hydrophobic interactions between the C18 chains and the bioactive lipid A component present on the LPS molecule. Various parameters such as pH, solvent, sonication time, NF concentration, alkane chain length, and density are optimized to achieve a maximum LPS capture efficiency. The NFs can be reused at least three times by simply breaking the NF-LPS complexes in the presence of food-grade surfactants, making the entire process safe, efficient, and scalable. The regenerated particles also serve as colorimetric labels in dot blot bioassays for simple and rapid estimation of the LPS removed.

Influence of External Forces during Supercooling on Dispersion Stability during Melt Emulsification

AbstractA special high‐pressure homogenization process – simultaneous homogenization and mixing (SHM) – was applied to produce hexadecane (C16H34), octadecane (C18H38), eicosane (C20H42), and docosane (C22H46) in water dispersions. Additionally, a high‐shear stress zone (HSSZ) was connected to the SHM unit to investigate the influence of external forces during supercooling on dispersion stability. The HSSZ did not affect the droplet disruption efficiency but induced aggregation behavior of the dispersed phase with increasing alkane chain length and dispersed‐phase content. High‐shear treatment during crystallization led to a change in particle shape, which was more favorable to aggregation.

Effect of Alkane Chain Length on Crystallization in Emulsions during Supercooling in Quiescent Systems and under Mechanical Stress

Crystallization behavior of hexadecane (C16H34), octadecane (C18H38), eicosane (C20H42), and docosane (C22H46) dispersions of similar mean droplet diameter (x50.2 ≈ 15 µm) was investigated in quiescent systems and compared to crystallization under mechanical stress. In quiescent systems, the required supercooling decreased with increasing chain length of the alkanes to initiate crystallization. Crystallization of alkane dispersions under mechanical stress resulted in similar onset crystallization supercooling, as during quiescent crystallization. Increase of mechanical stress did not affect the onset crystallization supercooling within alkane dispersions.

Guest Controlled Nonmonotonic Deep Cavity Cavitand Assembly State Switching.

Octa-acid (OA) and tetra-endo-methyl octa-acid (TEMOA) are water-soluble, deep-cavity cavitands with nanometer-sized nonpolar pockets that readily bind complementary guests, such as n-alkanes. Experimentally, OA exhibits a progression of 1:1 to 2:2 to 2:1 host/guest complexes (X:Y where X is the number of hosts and Y is the number of guests) with increasing alkane chain length from methane to tetradecane. Differing from OA only by the addition of four methyl groups ringing the portal of the pocket, TEMOA exhibits a nonmonotonic progression of assembly states from 1:1 to 2:2 to 1:1 to 2:1 with increasing guest length. Here we present a systematic molecular simulation study to parse the molecular and thermodynamic determinants that distinguish the succession of assembly stoichiometries observed for these similar hosts. Potentials of mean force between hosts and guests, determined via umbrella sampling, are used to characterize association free energies. These free energies are subsequently used in a reaction network model to predict the equilibrium distributions of assemblies. Our models accurately reproduce the experimentally observed trends, showing that TEMOA's endo-methyl units constrict the opening of the binding pocket, limiting the conformations available to bound guests and disrupting the balance between monomeric complexes and dimeric capsules. The success of our simulations demonstrate their utility at interpreting the impact of even simple chemical modifications on supramolecular assembly and highlight their potential to aid bottom-up design.

Liquid-liquid equilibrium data for extractive desulfurization using 1-butyl-3-methyl imidazolium thiocyanate, n-alkane and thiophene

The experimental liquid – liquid equilibrium (LLE) data for three ternary mixtures containing an ionic liquid (IL) (1-butyl-3-methyl imidazolium thiocyanate [Bmim][SCN]), alkanes (n-hexane, n-octane and n-decane) and sulfur compound (thiophene) have been measured experimentally. Distribution and selectivity coefficients have been calculated using experimental data. The LLE data have been obtained at 25 °C and ambient pressure. The experimental LLE data of ternary mixtures have been compared with our previous works. It has been shown that the IL with higher molecular weight of cation has higher solute distribution and lower selectivity coefficients. It has been found that the solubility decreases as the cation length decreases, meanwhile ILs cation chain length has a remarkable effect on solubility of alkanes. Moreover, the experimental data have been demonstrated that the selectivity decreases as alkane chain length of alkane decreases while the solubility of alkanes in the ILs increases, hence the removal costs of aromatic sulfur components will be increased. The results show that [Bmim][SCN] has the lowest alkane solubility and highest selectivity coefficient, in the system containing n-decane and thiophene. A comparative study reveals that compared to other ILs, [Bmim][SCN] is a more suitable solvent. Finally, the experimental data have been correlated utilizing non-randomness two liquid (NRTL) model. The binary energy parameters were obtained, it can be seen that the model can correlate the experimental data efficiently.

Experimental investigation of foam performance in the presence of crude oil

AbstractThe foam performance in the presence of oil plays an important role in foam application in enhancing oil recovery. The present study systematically investigated the effect of oil type, oil content, surfactant type, surfactant concentration, alkane chain length, salinity, and polymer concentration on foam performance in both the absence and presence of oil. The results showed that oil viscosity and oil density as well as oil component all contributed to foam performance in the presence of oil. Within a certain oil content, both light oil and heavy oil had a positive effect on foam, but heavy oil had a higher tendency to stabilize the foam. The order of foam performance by different surfactants was changed by the oil. It is noteworthy that heavy oil is detrimental to sodium dibutyl naphthalene sulfonate (BM) foam. Light oil can improve foam performance while heavy oil can harm foam in some specific cases. Lower salinity, longer alkane chain length, higher surfactant concentration and the presence of a polymer all benefited foam in the presence of crude oil.

Molecular dynamics modeling and simulation of lubricant between sliding solids

This paper presents molecular dynamic modeling and simulation of lubricant between sliding solids. Linear [Formula: see text]-alkanes with united atoms were used to model lubricant while iron sliding solids were modeled with body-centered cubic crystal lattices. We employed various potential functions, including the embedded atom method, the multibody force field and the Lennard–Jones potential, to approximate the interatomic interactions in the molecular model. Hydrodynamic lubrication was considered in this paper. We found that the temperature and the chain length of alkanes had effects on the friction between lubricated sliding solids. In addition, one debris, modeled as a nanoparticle, was added in the lubricant to study its effect on the friction. It was observed that nanoparticles would increase the friction in hydrodynamic lubrication.

Assessment of Self‐Assembled Monolayers as High‐Performance Thermal Interface Materials

Thermal interface materials (TIMs) are highly desirable for efficient thermal transfer or dissipation in a wide range of material and device applications. The self‐assembled monolayers (SAMs) are promising candidates for these applications due to their high thermal transparency and structural flexibility. In this work, the performance of SAMs as practical TIMs is assessed by performing atomistic simulations. The mixed nature of diffusive and ballistic thermal transport is identified across the monolayers from signatures of coherent energy propagation and strong phonon scattering processes, respectively. The interfacial thermal conductance (ITC), G, displays remarkable dependence on the length, N, packing density, n and stretch of alkane chains. The nonmonotonic G–N relation features a peak at N = 4 that corresponds to maximum overlap of the vibrational density of states between molecular chains and substrate. When n > 0.98 mols/nm2, phonon scattering between neighboring chains reduces the ITC. The ITC can be reduced by 32.9% under tensile strain of 23.9%, but remains almost unchanged under compression. Compared to other TIMs such as polymers, graphene, and carbon nanotubes, SAMs demonstrate simultaneously high thermal transparency and structural flexibility that can be further tailored through their molecular structures and mechanical loading conditions.

Biosynthesis of medium chain length alkanes for bio-aviation fuel by metabolic engineered Escherichia coli

The aim of this work was to study the synthesis of medium-chain length alkanes (MCLA), as bio-aviation product. To control the chain length of alkanes and increase the production of MCLA, Escherichia coli cells were engineered by incorporating (i) a chain length specific thioesterase from Umbellularia californica (UC), (ii) a plant origin acyl carrier protein (ACP) gene and (iii) the whole fatty acid synthesis system (FASs) from Jatropha curcas (JC). The genetic combination was designed to control the product spectrum towards optimum MCLA. Decanoic, lauric and myristic acid were produced at concentrations of 0.011, 0.093 and 1.657mg/g, respectively. The concentration of final products nonane, undecane and tridecane were 0.00062mg/g, 0.0052mg/g, and 0.249mg/g respectively. Thioesterase from UC controlled the fatty acid chain length in a range of 10–14 carbons and the ACP gene with whole FASs from JC significantly increased the production of MCLA.

Solvent induced supramolecular anisotropy in molecular gels

Herein is the first report of solvent induced anisotropy in 12-hydroxystearic acid self-assembled fibrillar networks. Increasing the chain length of polar solvent, such as nitriles and ketones, tailored the anisotropy of the fibrillar aggregates. 12HSA molecular gels, comprised of alkanes, exhibited an isotropic fibrillar network irrespective of the alkane chain length. In polar solvents, anisotropy, observed using 2D powder x-ray diffraction profiles, is correlated to a fibrillar supramolecular morphologies in long chain nitriles and ketones while sphereulitic crystals are correlated to x-ray diffraction patterns with an isotropic scatter intensity in short chain ketones and nitriles. These changes directly modify the final physical properties of the gels.

Effects of molecular structures on the pyrolysis and anti-coking performance of alkanes for thermal management

Pyrolysis of normal- and iso-alkanes were carried out using a supercritical cracking experimental apparatus equipped with an electrically heated tubular reactor under supercritical conditions (3.5MPa and 700°C). The hydraulic resistance method (HRM) was applied to quantitatively evaluate the carbon deposition. Effects of molecular structures on the pyrolysis and anti-coking performance of alkanes were studied. It was found that the gas yield and heat sink (HS) increased with the increasing carbon chain length of normal alkanes. Normal alkanes with even carbon number (NPEC) exhibited better anti-coking performance than those with adjacent odd carbon number (NPOC). Compared with normal alkanes, iso-alkanes could generate higher gas yields. However, lower HS and yield of hydrogen and alkenes (⩽C4), as well as poorer resistance to carbon deposition were observed for iso-alkanes with more than two methyls. There was an optimum value of the ratio of NPEC/NPOC for the balanced HS and anti-coking performance in the design of high-performance endothermic hydrocarbon fuels (EHFs).

Density, Viscosity, Speed of Sound, Bulk Modulus, Surface Tension, and Flash Point of Binary Mixtures of Butylbenzene + Linear Alkanes (n-Decane, n-Dodecane, n-Tetradecane, n-Hexadecane, or n-Heptadecane) at 0.1 MPa

This work reports physical property measurements of binary mixtures of butylbenzene with n-decane, n-dodecane, n-tetradecane, n-hexadecane, or n-heptadecane. Densities and viscosities were measured at temperatures from (293.15 to 373.15) K, and speeds of sound were measured at temperatures from (293.15 to 333.15) K, except for those of n-heptadecane, which were measured starting at 303.15 K. Densities increased with increasing mole fraction of butylbenzene. Excess molar volumes were positive and increased with increasing alkane chain length, except for those of heptadecane which were similar to those of n-hexadecane. Analysis of excess molar volumes using the Prigogine–Flory–Patterson model showed that the interaction term contributed more to excess molar volume than the free volume or P* term. As the mole fraction of butylbenzene increased, speeds of sound increased for n-decane and n-dodecane mixtures but decreased for other alkane mixtures to values below those of both pure components before increasing...

Chain Length and Solvent Control over the Electronic Properties of Alkanethiolate-Protected Gold Nanoparticles at the Molecule-to-Metal Transition.

Alkanethiolate protected gold nanoparticles are one of the most widely used systems in modern science and technology, where the emergent electronic properties of the gold core are valued for use in applications such as plasmonic solar cells, photocatalysis, and photothermal heating. Though choice in alkane chain length is not often discussed as a way in which to control the electronic properties of these nanoparticles, we show that the chain length of the alkyl tail exerts clear control over the electronic properties of the gold core, as determined by conduction electron spin resonance spectroscopy. The control exerted by chain length is reported on by changes to the g-factor of the metallic electrons, which we can relate to the average surface potential on the gold core. We propose that the surface potential is modulated by direct charge donation from the ligand to the metal, resulting from the formation of a chemical bond. Furthermore, the degree of charge transfer is controlled by differences between the dielectric constant of the medium and the ligand shell. Together, these observations are used to construct a simple electrostatic model that provides a framework for understanding how surface chemistry can be used to modulate the electronic properties of gold nanoparticles.

Effect of organic acid chain length on foam performance in a porous medium

ABSTRACTWe have systematically studied the effect of organic acid chain length on surface dilatational properties and foam flow performance in a porous medium. Surface dilatational properties were studied by oscillating drop module (ODM). ODM results in deionized water show that sufficient long chain length of organic acid is an essential requirement for high surface dilatational modulus. While, to various salinities, surfactant to acid ratio of achieving high surface dilatational modulus varies. Foam flow tests show that surface dilatational modulus has decisive effect on produced foam size, which partially determines foam flow pressure drop. Both surface dilatational modulus and surface tension determine foam flow pressure drop. Besides, surface loss modulus also contributes to pressure drop. Bulk foam tests show that addition of organic acids with proper chain length can enhance foam tolerance to oil significantly. Compared with alkane chain length, acid with longer chain has good ability in stabilizing foam. At last, foam flooding tests show that surface dilatational modulus and foam tolerance to oil play important roles in foam enhanced oil recovery.

The effect of surface nano-corrugation on the squeeze-out of molecular thin hydrocarbon films between curved surfaces with long range elasticity

The properties of linear alkane lubricants confined between two approaching solids are investigated by a model that accounts for the roughness, curvature and elastic properties of the solid surfaces. We consider linear alkanes of different chain lengths from to , confined between corrugated solid walls. The pressure necessary to squeeze out the lubricant increases rapidly with the alkane chain length, but is always much lower than in the case of smooth surfaces. The longest alkanes form domains of ordered chains and the squeeze-out appears to nucleate in the more disordered regions between these domains. The short alkanes stay fluid-like during the entire squeeze out process which result in a very small squeeze-out pressure which is almost constant during the squeeze-out of the last monolayer of the fluid. In all cases we observe lubricant trapped in the valley of the surface roughness, which cannot be removed independent of the magnitude of the squeezing pressures.

Synthesis of Fuel Intermediates from HMF/Fructose

Alkylation of toluene, anisole and mesitylene with HMF and fructose is reported using Glu–Fe3O4–SO3H solid acid catalyst. HMF was found to alkylate toluene, anisole and mesitylene in high yields and high selectivity under solvent free conditions. Polyalkylation and self etherification of HMF was not observed. The alkylated product on hydrodeoxygenation forms liquid alkanes of different chain lengths which have properties of transportation fuels or diesel fuels. The catalyst was easily recoverable and reusable minimum 5 times to achieve good yields and high selectivity of alkylated product.

Paleoclimate significance of n-alkane molecular distributions and δ2H values in surface peats across the monsoon region of China

Leaf wax molecular distributions and isotopic values are generally considered paleohydrologic proxies. Here we evaluate the sensitivity of alkane chain length distributions and compound-specific hydrogen isotopic compositions (δ2Halk) in surface peats to environmental parameters across the monsoon region of China. The alkane average chain length (ACL), carbon predominance index (CPI) and δ2Halk values show relatively large variations in multiple samples from a single site, highlighting the complexity of the processes affecting these ratios at small spatial scales. Nonetheless, the site-averaged CPI values correlate significantly with the mean annual temperature (r=−0.57, p(α)<0.001) and precipitation (r=−0.53, p(α)<0.001), suggesting that climate is important to control CPI values, together with other influences. The large variation of δ2Halk values in a single peatland suggests that δ2Halk values may be affected by factors in addition to biosynthetic isotopic discrimination and the D/H ratio of the water available to the plants. It is interesting to note that the site-averaged δ2Halk values correlate poorly with the modeled yearly δ2Hp values. In addition, the site-averaged apparent hydrogen isotope fractionation between C31n-alkanes and precipitation correlates with mean annual temperature. Together, our results show a relatively complex spatial pattern of δ2Halk values in a single peatland or along a climate transection. Thus, we caution that δ2Halk values would be affected by a series of factors, including the growth season length, the lipid synthesis time, the plant life forms, and/or the hydrogen isotope discrimination during lipid biosynthesis. More study is clearly required to elucidate the major controllers.

Liquid–liquid extraction of toluene from alkane with pyridinium based ionic liquid ([BPy][NO3] and [HPy][NO3]) at 298.15 K and atmospheric pressure

The focus of this paper is to study the liquid−liquid extraction process for the separation of toluene from alkane employing the ionic liquids N-butylpyridinium nitrate, [BPy][NO3], and N-hexylpyridinium nitrate, [HPy][NO3], as a new solvents. New experimental data for the ternary systems of {[BPy][NO3] (1)+heptane, or octane, or decane (2)+toluene (3)} and {[HPy][NO3] (1)+heptane, or octane, or decane (2)+toluene (3)} at T=298.15K and atmospheric pressure are reported. The Othmer-Tobias and Hand correlation are examined to check the reliability of the experimental LLE data. The toluene distribution ratios and selectivity were calculated form the experimental data. The selectivity values are higher than unity which indicates the ILs, [BPy][NO3] and [HPy][NO3], used in this work are potential solvents to separate toluene from alkane. Besides, the effect of the alkane chain length in the selectivity values was evaluated. In addition, the result of the NRTL thermodynamic modeling shows, the experimental data were satisfactorily correlated.