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Sample records for n-pentane n-hexane n-heptane

  1. A model of reduced oxidation kinetics using constituents and species: Iso-octane and its mixtures with n-pentane, iso-hexane and n-heptane

    SciTech Connect

    Harstad, Kenneth; Bellan, Josette

    2010-11-15

    A previously described methodology for deriving a reduced kinetic mechanism for alkane oxidation and tested for n-heptane is here shown to be valid, in a slightly modified version, for iso-octane and its mixtures with n-pentane, iso-hexane and n-heptane. The model is still based on partitioning the species into lights, defined as those having a carbon number smaller than 3, and heavies, which are the complement in the species ensemble, and mathematically decomposing the heavy species into constituents which are radicals. For the same similarity variable found from examining the n-heptane LLNL mechanism in conjunction with CHEMKIN II, the appropriately scaled total constituent molar density still exhibits a self-similar behavior over a very wide range of equivalence ratios, initial pressures and initial temperatures in the cold ignition regime. When extended to larger initial temperatures than for cold ignition, the self-similar behavior becomes initial temperature dependent, which indicates that rather than using functional fits for the enthalpy generation due to the heavy species' oxidation, an ideal model based on tabular information extracted from the complete LLNL kinetics should be used instead. Similarly to n-heptane, the oxygen and water molar densities are shown to display a quasi-linear behavior with respect to the similarity variable, but here their slope variation is no longer fitted and instead, their rate equations are used with the ideal model to calculate them. As in the original model, the light species ensemble is partitioned into quasi-steady and unsteady species; the quasi-steady light species mole fractions are computed using the ideal model and the unsteady species are calculated as progress variables using rates extracted from the ideal model. Results are presented comparing the performance of the model with that of the LLNL mechanism using CHEMKIN II. The model reproduces excellently the temperature and species evolution versus time or versus the similarity variable, with the exception of very rich mixtures, where the predictions are still very good but the multivalued aspect of these functions at the end of oxidation is not captured in the reduction. The ignition time is predicted within percentages of the LLNL values over a wide range of equivalence ratios, initial pressures and initial temperatures. (author)

  2. Thermodynamics of acrylic esters containing binary liquid mixtures. I. Excess volumes and isentropic compressibilities of alkyl methacrylates + n-hexane, + n-heptane, + carbon tetrachloride, + chlorobenzene, and o-dichlorobenzene at 303.15 K

    NASA Astrophysics Data System (ADS)

    Sastry, N. V.; Dave, P. N.

    1996-11-01

    Excess volumes and isentropic compressibilities of 15 binary liquid mixtures containing methyl methacrylate (MMA). ethyl methacrylate (EMA), and butyl methacrylate (BM) and n-Hexane, n-heptane, carbon tetrachloride chlorobenzene and o-dichlorobenzene are derived from the measured densities and speeds of sound at 303.15 K. The dependence of the excess volumes and the isentropic compressibilities both on the alkyl chain length and on the nature of the solvent shots the dominance of dispersing interactions in the mixtures of aliphatic hydrocarbons and specific interactions im the chlorinated solvent mixtures. The speeds of sound of binary mixtures of MMA were found to be reasonably predicted by free length and collision factor theories. An attempt is also made to estimate the individual contributions of interactional. free volume and P * effects to the overall excess volumes of binary mixtures containing MMA. The results indicate that the three factors are equally responsible for the observed values.

  3. n-Heptane

    Integrated Risk Information System (IRIS)

    n - Heptane ; CASRN 142 - 82 - 5 Human health assessment information on a chemical substance is included in the IRIS database only after a comprehensive review of toxicity data , as outlined in the IRIS assessment development process . Sections I ( Health Hazard Assessments for Noncarcinogenic Effec

  4. n-Hexane

    Integrated Risk Information System (IRIS)

    n - Hexane ; CASRN 110 - 54 - 3 Human health assessment information on a chemical substance is included in the IRIS database only after a comprehensive review of toxicity data , as outlined in the IRIS assessment development process . Sections I ( Health Hazard Assessments for Noncarcinogenic Effect

  5. Replacing xylene with n-heptane for paraffin embedding.

    PubMed

    Stockert, J C; López-Arias, B; Del Castillo, P; Romero, A; Blázquez-Castro, A

    2012-10-01

    In standard histological technique, aromatic solvents such as xylene and toluene are used as clearing agents between ethanol dehydration and paraffin embedding. In addition, these solvents are used for de-waxing paraffin sections. Unfortunately, these solvents are harmful and therefore adequate substitutes would be useful. We suggest the use of n-heptane as a convenient substitute for xylene. Paraffin sections of rat tissues processed with n-heptane and stained with hematoxylin-eosin or Masson's trichrome showed proper embedment, well preserved morphology and excellent staining. PMID:22853037

  6. Effect of methanol on the biofiltration of n-hexane.

    PubMed

    Zehraoui, Abderrahman; Hassan, Ashraf Aly; Sorial, George A

    2012-06-15

    This study investigated the removal of recalcitrant compounds in the presence of a hydrophilic compound. n-Hexane is used as a model compound to represent hydrophobic compounds. Methanol has been introduced in mixture with n-hexane in order to increase the bioavailability of n-hexane in trickle-bed-air-biofilters (TBABs). The mixing ratios investigated were: 70% methanol:30% n-hexane, and 80% methanol:20% n-hexane by volume. n-Hexane loading rates (LRs) ranged from 0.9 to 13.2 g m(-3) h(-1). Methanol LRs varied from 4.6 to 64.5 g m(-3) h(-1) and from 2.3 to 45.2 g m(-3) h(-1) depending upon the mixing ratio used. Biofilter performance, effect of mixing ratios of methanol to n-hexane, removal profile along biofilter depth, COD/nitrogen consumption and CO(2) production were studied under continuous loading operation conditions. Results have shown that the degradation of n-hexane is significantly enhanced by the presence of methanol for n-hexane LRs less than 13.2 g m(-3) h(-1). For n-hexane LR greater than 13.2 g m(-3) h(-1), even though methanol had impacted n-hexane biodegradation, its removal efficiency was higher than our previous study for biodegradation of n-hexane alone, in presence of surfactant, or in presence of benzene. On the other hand, the degradation of methanol was not impacted by the presence of n-hexane. PMID:22516522

  7. Adsorption of nPentane on Mesoporous Silica and Adsorbent Deformation

    E-print Network

    Muzzio, Fernando J.

    Adsorption of nPentane on Mesoporous Silica and Adsorbent Deformation Gennady Yu. Gor,*, Oskar 08854, United States ABSTRACT: Development of quantitative theory of adsorption-induced deforma- tion of mesoporous silica by n-pentane adsorption. The shape of experimental strain isotherms for this system differs

  8. Reaction zone visualisation in swirling spray n-heptane flames

    E-print Network

    Yuan, R.; Kariuki, J.; Dowlut, A.; Balachandran, R.; Mastorakos, E.

    2014-06-26

    advanced turbulent combustion models. In gas turbines and industrial furnaces, the flame is virtually always stabilised by swirl. It can be argued that we know little about the fundamental processes of extinction of spray flames in recirculation zones... flames could be made. In this paper, we use simultaneous CH2O and OH imaging in the stabilisation region of an n-heptane spray flame in a swirl-induced recirculation zone, a configuration of great relevance to gas turbine combustion, and in particular...

  9. Rich n-heptane and diesel combustion in porous media

    SciTech Connect

    Pastore, A.; Mastorakos, E.

    2010-04-15

    Rich n-heptane and diesel flames in two-layer porous media are experimentally investigated in the context of syngas production. The stable operating points of n-heptane reforming have been determined and the mole fractions of H{sub 2}, CO, CO{sub 2} and light hydrocarbons have been measured in the exhaust gas at an equivalence ratio of 2 for different thermal input values. The reformer performance has been assessed also from the point of view of the heat losses and the mixture homogeneity. The pre-vapouriser produces an approximately uniform vapour-air mixture upstream of the flame front. The range of flow rates for stable flames decreased with increasing equivalence ratio. Heat losses were about 10% of the thermal input at high firing rates. A 77.2% of the equilibrium H{sub 2} was achieved at a flame speed of 0.82 m/s. The same reactor with a different porous matrix for the reforming stage demonstrates diesel reforming to syngas with a conversion efficiency of 77.3% for a flame speed of 0.65 m/s. (author)

  10. Industrial application of catalytic systems for n-heptane isomerization.

    PubMed

    Alemán-Vázquez, Laura Olivia; Cano-Domínguez, José Luis; Torres-García, Enelio; Villagómez-Ibarra, José Roberto

    2011-01-01

    The ideal gasoline must have a high pump octane number, in the 86 to 94 range, and a low environmental impact. Alkanes, as a family, have much lower photochemical reactivities than aromatics or olefins, but only the highly branched alkanes have adequate octane numbers. The purpose of this work is to examine the possibilities of extending the technological alternative of paraffin isomerization to heavier feedstocks (i.e., n-heptane) using non-conventional catalytic systems which have been previously proposed in the literature: a Pt/sulfated zirconia catalyst and a molybdenum sub-oxide catalyst. Under the experimental conditions at which these catalysts have been evaluated, the molybdenum sub-oxide catalyst maintains a good activity and selectivity to isomerization after 24 h, while the Pt/sulfated zirconia catalyst shows a higher dimethylpentanes/methylhexanes ratio, probably due to a lower operating temperature, but also a high formation of cracking products, and presents signs of deactivation after 8 h. Though much remains to be done, the performance of these catalysts indicates that there are good perspectives for their industrial application in the isomerization of n-heptane and heavier alkanes. PMID:21760573

  11. The Burning of Large N-Heptane Droplets in Microgravity

    NASA Technical Reports Server (NTRS)

    Manzello, Samuel L.; Choi, Mun Young; Kazakov, Andrei; Dryer, Frederick L.; Dobashi, Ritsu; Hirano, Toshisuke; Ferkul, Paul (Technical Monitor)

    2000-01-01

    Experimental results are presented on the burning and sooting behavior of large n-heptane droplets in air at atmospheric pressure under microgravity conditions. The experiments were performed at the Japanese Microgravity Center (JAMIC) 10 sec dropshaft in Hokkaido, Japan. Soot volume fraction, burning rate, flame standoff and luminosity were measured for droplets of 2.6 mm and 2.9 mm in initial diameter. These are the largest droplets for which soot volume fraction measurements have ever been performed. Previous measurements of soot volume fractions for n-heptane droplets, confined to smaller droplet sizes of less than 1.8 mm, indicated that maximum soot volume fraction increased monotonically with initial droplet size. The new results demonstrate for the first time that sooting tendency is reduced for large droplets as it has been speculated previously but never confirmed experimentally. The lower soot volume fractions for the larger droplets were also accompanied by higher burning rates. The observed phenomenon is believed to be caused by the dimensional influence on radiative heat losses from the flame. Numerical calculations confirm that soot radiation affects the droplet burning behavior.

  12. n-Hexane metabolism in occupationally exposed workers.

    PubMed Central

    Mutti, A; Falzoi, M; Lucertini, S; Arfini, G; Zignani, M; Lombardi, S; Franchini, I

    1984-01-01

    Lung uptake and excretion of n-hexane were studied in ten workers in a shoe factory. Simultaneous samples of inhaled and alveolar air were collected with the aid of a Rhan-Otis valve, personal samplers, and charcoal tubes. Alveolar excretion was monitored during a six hour postexposure period. Uptake was calculated from lung ventilation, the retention coefficient, and environmental concentrations. The amount of exhaled n-hexane was calculated from the decay curve. According to the experimental data, alveolar retention was about 25% of the inhaled n-hexane, corresponding to a lung uptake of about 17%. The postexposure alveolar excretion was about 10% of the total uptake. The main metabolites of n-hexane were identified and measured by capillary GC/MS in spot urine samples collected before, at the end, and 15 hours after the same working shift. Urinary concentrations were low, though related to n-hexane in the air. 2,5-Hexanedione in the end of shift samples gave the best estimate of overall exposure. About 3 mg/g creatinine of 2,5-hexanedione would correspond to about 50 ppm of n-hexane in the air (mean daily exposure). PMID:6498115

  13. N-heptane adsorption and desorption in mesoporous materials

    NASA Astrophysics Data System (ADS)

    Zaleski, R.; Gorgol, M.; B?azewicz, A.; Kierys, A.; Goworek, J.

    2015-06-01

    Positron Annihilation Lifetime Spectroscopy (PALS) was used for an in situ monitoring of adsorption and desorption processes. The disordered and ordered porous silica as well as the porous polymer were used as adsorbents, while an adsorbate in all the cases was n-heptane. The lifetimes and particularly the intensities of the ortho-positronium(o-Ps) components depend strongly on the adsorbate pressure. The analysis of these dependencies allows us to identify several processes, which are taking place during sorption. At low pressure, an island-like growth of the first layers of the adsorbate on the silica, in a contrary to a swelling of the polymer, is observed. A size of the pores, which remain empty, is estimated at the subsequent stages of the adsorbate condensation and evaporation. The adsorbate thrusting into micropores is deduced at p/p0 > 0.6 whilst the mesopores are still not completely filled.

  14. Selective optical detection of n-heptane/iso-octane vapors by polyimide lightguides

    NASA Astrophysics Data System (ADS)

    Podgorsek, R. P.; Franke, H.; Feger, C.

    1995-03-01

    The optical anisotropy of planar polyimide lightguides in an atmosphere of n-heptane / iso-octane is investigated in a transient experiment for pure and several mixed-vapor concentrations. The polymer sensor responds only to n-heptane and not to iso-octane vapors. However, the presence of the latter affects the dynamic behavior of the waveguide anisotropy, which can be fitted by a stretched exponential time dependence. The saturation values of the birefringence are an absolute measure for the n-heptane concentration and are not affected by the presence of the iso-octane vapors.

  15. Effects of Equivalence Ratio on Species and Soot Concentrations in Premixed N-Heptane Flames

    E-print Network

    Senkan, Selim M.

    octane number. The oxida- tion of n-heptane has been investigated in shock tubes [1, 2], jet, respectively. Soot particle diameters, number densities, and volume fractions were determined using classical

  16. Multiplicity of n-heptane oxidation pathways catalyzed by cytochrome P450.

    PubMed

    Szutowski, Miros?aw M; Rakoto, Joseph S

    2009-01-01

    Modeling, mutagenesis, and kinetic studies have demonstrated that the substrate-binding site of cytochrome P450 is composed of multiple interactive regions that are capable of simultaneously binding two or more xenobiotics. Substrate molecules can interact with each other after docking. Thus, substrates can compete for the activated oxygen-ferrous complex or alter the spatial orientation of other molecules. Cytochrome P450 is a unique enzyme that produces n-heptane metabolites of different oxidation states. Metabolism of n-heptane was investigated with rat liver microsomes and a reconstituted rat liver system. Ethanol, n-propanol, and n-butanol molecules interacted with the n-heptane molecule and resulted in cytochrome P450 spectral changes as well as alterations in the n-heptane metabolic profile. The observed modifications in the biotransformation of n-heptane indicated that there are three distinct pathways for oxidation of n-heptane to heptanols, heptanones, and one-side oxygen-oriented heptanediones. PMID:19705363

  17. Separation of Fischer-Tropsch Wax from Catalyst Using Near-Critical Fluid Extraction: Analysis of Process

    E-print Network

    Kilpatrick, Peter K.

    100. Four light solvents were evaluated: n-pentane, n-hexane, n-heptane, and n-octane. These four of paraffins, olefins, and alcohols of different carbon numbers. The exact composition depends for the formation of high- carbon-number paraffins is: The reaction is highly exothermic, which creates a major

  18. Evaluation of chemical-kinetics models for n-heptane combustion using a multidimensional CFD code

    E-print Network

    Aggarwal, Suresh K.

    Evaluation of chemical-kinetics models for n-heptane combustion using a multidimensional CFD code Chemical kinetics Modeling Diffusion flames Premixed flames a b s t r a c t Computational fluid dynamics-heptane fuel. Three state-of-the-art chemical kinetics models are incorporated into a time-dependent, two

  19. Absorption and recovery of n-hexane in aqueous solutions of fluorocarbon surfactants.

    PubMed

    Xiao, Xiao; Yan, Bo; Fu, Jiamo; Xiao, Xianming

    2015-11-01

    n-Hexane is widely used in industrial production as an organic solvent. As an industrial exhaust gas, the contribution of n-hexane to air pollution and damage to human health are attracting increasing attention. In the present study, aqueous solutions of two fluorocarbon surfactants (FSN100 and FSO100) were investigated for their properties of solubilization and dynamic absorption of n-hexane, as well as their capacity for regeneration and n-hexane recovery by thermal distillation. The results show that the two fluorocarbon surfactants enhance dissolution and absorption of n-hexane, and their effectiveness is closely related to their concentrations in solution. For low concentration solutions (0.01%-0.30%), the partition coefficient decreases dramatically and the saturation capacity increases significantly with increasing concentration, but the changes for both are more modest when the concentration is over 0.30%. The FSO100 solution presents a smaller partition coefficient and a greater saturation capacity than the FSN100 solution at the same concentration, indicating a stronger solubilization for n-hexane. Thermal distillation is a feasible method to recover n-hexane from these absorption solutions, and to regenerate them. With 90sec heating at 80-85°C, the recovery of n-hexane ranges between 81% and 85%, and the regenerated absorption solution maintains its original performance during reuse. This study provides basic information on two fluorocarbon surfactants for application in the treatment of industrial n-hexane waste gases. PMID:26574100

  20. Distribution of pesticides in n-hexane/water and n-hexane/acetonitrile systems and estimation of possibilities of their extraction isolation and preconcentration from various matrices.

    PubMed

    Zayats, M F; Leschev, S M; Petrashkevich, N V; Zayats, M A; Kadenczki, L; Szitás, R; Szemán Dobrik, H; Keresztény, N

    2013-04-24

    Distribution of 150 most widely used pesticides of different chemical classes (amides, anilinopirimidines, aromatics, benzenesulfonates, carbamates, dicarboximides, organophosphorus compounds, phenyl esters, phenylureas, pyrazoles, pyrethroids, pyrimidines, strobilurins, sulfamides, triazines, triazoles, etc.) in n-hexane/water and n-hexane/acetonitrile systems was investigated at 25°C. Distribution constants of pesticides (P) have been calculated as ratio of pesticide concentration in n-hexane to its concentration in water or acetonitrile phase. HPLC and GC methods were used for pesticides determination in phases. It was found that the overwhelming majority of pesticides are hydrophobic, i.e. in n-hexane/water system LgP?0, and the difference in LgP values can reach 9.1 units. Replacement of water for acetonitrile leads to dramatic fall of LgP values reaching 9.5 units. The majority of LgP values in this case are negative and their differences is strongly leveled in comparison with a hexane/water system. Thus, maximal difference in pesticides LgP values for n-hexane/acetonitrile system is 3.2 units. It is shown that n-hexane can be used for selective and efficient extraction and preconcentration of pesticides from water matrices. On the other hand, acetonitrile is effective for the isolation and preconcentration of pesticides from hydrocarbon and vegetable oil matrices. The distribution constants described in the paper may be effectively used for the estimation of possibilities of extraction isolation, preconcentration and separation of pesticides. PMID:23567114

  1. IRIS Toxicological Review and Summary Documents for N-Hexane (External Review Draft)

    EPA Science Inventory

    EPA's assessment of the noncancer health effects and carcinogenic potential of n-hexane was last prepared and added to the IRIS data base in 1990. The IRIS program is updating the IRIS assessment for n-hexane; this update will incorporate health effects information published sin...

  2. A model-free temperature-dependent conformational study of n-pentane in nematic liquid crystals

    NASA Astrophysics Data System (ADS)

    Burnell, E. Elliott; Weber, Adrian C. J.; Dong, Ronald Y.; Meerts, W. Leo; de Lange, Cornelis A.

    2015-01-01

    The proton NMR spectra of n-pentane orientationally ordered in two nematic liquid-crystal solvents are studied over a wide temperature range and analysed using covariance matrix adaptation evolutionary strategy. Since alkanes possess small electrostatic moments, their anisotropic intermolecular interactions are dominated by short-range size-and-shape effects. As we assumed for n-butane, the anisotropic energy parameters of each n-pentane conformer are taken to be proportional to those of ethane and propane, independent of temperature. The observed temperature dependence of the n-pentane dipolar couplings allows a model-free separation between conformer degrees of order and conformer probabilities, which cannot be achieved at a single temperature. In this way for n-pentane 13 anisotropic energy parameters (two for trans trans, tt, five for trans gauche, tg, and three for each of gauche+ gauche+, pp, and gauche+ gauche-, pm), the isotropic trans-gauche energy difference Etg and its temperature coefficient Etg ' are obtained. The value obtained for the extra energy associated with the proximity of the two methyl groups in the gauche+ gauche- conformers (the pentane effect) is sensitive to minute details of other assumptions and is thus fixed in the calculations. Conformer populations are affected by the environment. In particular, anisotropic interactions increase the trans probability in the ordered phase.

  3. A model-free temperature-dependent conformational study of n-pentane in nematic liquid crystals

    SciTech Connect

    Burnell, E. Elliott; Weber, Adrian C. J.; Dong, Ronald Y.; Meerts, W. Leo; Lange, Cornelis A. de

    2015-01-14

    The proton NMR spectra of n-pentane orientationally ordered in two nematic liquid-crystal solvents are studied over a wide temperature range and analysed using covariance matrix adaptation evolutionary strategy. Since alkanes possess small electrostatic moments, their anisotropic intermolecular interactions are dominated by short-range size-and-shape effects. As we assumed for n-butane, the anisotropic energy parameters of each n-pentane conformer are taken to be proportional to those of ethane and propane, independent of temperature. The observed temperature dependence of the n-pentane dipolar couplings allows a model-free separation between conformer degrees of order and conformer probabilities, which cannot be achieved at a single temperature. In this way for n-pentane 13 anisotropic energy parameters (two for trans trans, tt, five for trans gauche, tg, and three for each of gauche{sub +} gauche{sub +}, pp, and gauche{sub +} gauche{sub ?}, pm), the isotropic trans-gauche energy difference E{sub tg} and its temperature coefficient E{sub tg}{sup ?} are obtained. The value obtained for the extra energy associated with the proximity of the two methyl groups in the gauche{sub +} gauche{sub ?} conformers (the pentane effect) is sensitive to minute details of other assumptions and is thus fixed in the calculations. Conformer populations are affected by the environment. In particular, anisotropic interactions increase the trans probability in the ordered phase.

  4. Asymptotic analysis with reduced chemistry for the burning of n-heptane droplets

    NASA Technical Reports Server (NTRS)

    Card, J. M.; Williams, F. A.

    1992-01-01

    The method of rate-ratio asymptotics is used with reduced chemistry to analyze the flame structure and extinction of an isolated n-heptane droplet burning under quasisteady, spherically symmetrical conditions. The outer transport zones are described by the classical Burke-Schumann solution. The inner reaction zone consists of a thin layer, on the rich side of the flame, where the fuel is consumed, and on the lean side, a broader but still asymptotically thin oxidation layer, where H2 and CO are consumed. Special attention is given to differences in predictions of extinction conditions, caused by different chemical-kinetic approximations in the reduced chemistry, including fuel-chemistry effects through molecules containing more than one carbon atom. From the analysis, extinction diameters for n-heptane droplets are estimated for different pressures and ambient oxygen concentrations. The results show that extinction diameters are extremely sensitive to the number of radicals consumed in breaking down each fuel molecule.

  5. Elasticity and phase behaviour of n-heptane and n-nonane in nanopores

    NASA Astrophysics Data System (ADS)

    Schappert, Klaus; Gemmel, Laura; Meisberger, Dennis; Pelster, Rolf

    2015-09-01

    Here we present an ultrasonic study on the elasticity of normal alkanes (n-heptane and n-nonane) in the nanopores of porous Vycor glass (average pore radius rP = 2.74 \\text{nm} ). Above the melting temperature we have found a non-zero shear modulus for both n-heptane and n-nonane, which is also typical for the rotator phases of bulk alkanes at temperatures below the melting temperature. This points to the formation of a special molecular order of the adsorbed alkanes. Furthermore, the alkanes undergo a continuous stiffening over a broad temperature range (of ? T > 60 \\text{K} for heptane or ? T > 120 \\text{K} for nonane). The results clearly indicate that nanoconfinement induces an extremely broad continuous transition of heptane and nonane into a crystalline low-temperature phase.

  6. Model for the partition of neutral compounds between n-heptane and formamide.

    PubMed

    Karunasekara, Thushara; Poole, Colin F

    2010-04-01

    Partition coefficients for 84 varied compounds were determined for n-heptane-formamide biphasic partition system and used to derive a model for the distribution of neutral compounds between the n-heptane-rich and formamide-rich layers. The partition coefficients, log K(p), were correlated through the solvation parameter model giving log K(p)=0.083+0.559E-2.244S-3.250A-1.614B+2.387V with a multiple correlation coefficient of 0.996, standard error of the estimate 0.139, and Fisher statistic 1791. In the model, the solute descriptors are excess molar refraction, E, dipolarity/polarizability, S, overall hydrogen-bond acidity, A, overall hydrogen-bond basicity, B, and McGowan's characteristic volume, V. The model is expected to be able to estimate further values of the partition coefficient to about 0.13 log units for the same descriptor space covered by the calibration compounds (E=-0.26-2.29, S=0-1.93, A=0-1.25, B=0.02-1.58, and V=0.78-2.50). The n-heptane-formamide partition system is shown to have different selectivity to other totally organic biphasic systems and to be suitable for estimating descriptor values for compounds of low water solubility and/or stability. PMID:20187036

  7. Effect of Fuel Molecular Structure and Premixing on Soot Emissions from nHeptane and 1Heptene Flames

    E-print Network

    Aggarwal, Suresh K.

    observed that the fuel reactivity and ignition behavior are strongly influenced by the presence and number, while n-heptane and iso-octane have been considered as surrogates for diesel and gasoline fuels

  8. Esterification kinetics of triglycerides in n-hexane catalyzed by an immobilized lipase 

    E-print Network

    Gomez Ruiz, Alejandro

    1998-01-01

    The kinetics of enzyme-catalyzed esterification of triglycerides over immobilized lipase in n-hexane was investigated. The reaction kinetics were described in terms of a mechanism developed following the Langmuir-Hinshelwood-Hougen-Watson (LHHW...

  9. Reference Correlations of the Thermal Conductivity of Cyclopentane, iso-Pentane, and n-Pentane

    NASA Astrophysics Data System (ADS)

    Vassiliou, C.-M.; Assael, M. J.; Huber, M. L.; Perkins, R. A.

    2015-09-01

    New, wide-range reference equations for the thermal conductivity of cyclopentane, iso-pentane, and n-pentane are presented. The equations are based in part upon a body of experimental data that has been critically assessed for internal consistency and for agreement with theory whenever possible. In the case of the dilute-gas thermal conductivity, a theoretically based correlation was adopted in order to extend the temperature range of the experimental data. In the critical region, the enhancement of the thermal conductivity is well represented by theoretically based equations containing just one adjustable parameter, estimated by a predictive scheme. The thermal-conductivity equations behave in a physically reasonable manner over a wide range of conditions that correspond to the range of validity of the most accurate equations of state for each fluid. The estimated uncertainties of the correlations are dependent on the availability of accurate experimental data for validation, and are different for each fluid, varying from 1% (at the 95% confidence level) for the liquid phase of iso-pentane over the temperature range 307 K

  10. [Measurements of the ignition delay times of n-heptane by using characteristic emission from OH radical].

    PubMed

    Xie, Wei; Li, Ping; Zhang, Chang-Hua; Niu, Na; Nie, Xiao-Fei; Li, Cong-Shan

    2011-02-01

    Using a measurement system consisting of a monochromator, a photomultiplier tube (PMT), piezoelectric pressure sensors and a digital oscilloscope, the ignition delay times of n-heptane/O2 mixture were measured behind reflected shock waves in a chemical shock tube, the onset of ignition was indicated by the steepest rise of the characteristic emission from OH radical at 306.4 nm. The experimental conditions cover temperatures from 1 170 to 1 730 K, pressures at (1.0 +/- 0.1) and (0.75 +/- 0.05) atm, and equivalence ratio of 1.0. Under these experimental conditions, the correlation formulas of ignition delay time dependence on the temperature for n-heptane have been obtained. Present results indicate that the ignition delay times of n-heptane decreases exponentially with the increase in temperatures. While temperature increases, the change rate of ignition delay time of n-heptane under the pressure of 0.75 atm is less than that of 1.0 atm. Present ignition delay data are important for constructing the kinetic model of the combustion reaction and provide an experimental criterion for validating the combustion reaction mechanism of n-heptane. PMID:21510410

  11. Experimental and modeling investigation of the low-temperature oxidation of n-heptane

    PubMed Central

    Herbinet, Olivier; Husson, Benoit; Serinyel, Zeynep; Cord, Maximilien; Warth, Valérie; Fournet, René; Glaude, Pierre-Alexandre; Sirjean, Baptiste; Battin-Leclerc, Frédérique; Wang, Zhandong; Xie, Mingfeng; Cheng, Zhanjun; Qi, Fei

    2013-01-01

    The low-temperature oxidation of n-heptane, one of the reference species for the octane rating of gasoline, was investigated using a jet-stirred reactor and two methods of analysis: gas chromatography and synchrotron vacuum ultra-violet photo-ionization mass spectrometry (SVUV-PIMS) with direct sampling through a molecular jet. The second method allowed the identification of products, such as molecules with hydroperoxy functions, which are not stable enough to be detected using gas chromatography. Mole fractions of the reactants and reaction products were measured as a function of temperature (500-1100K), at a residence time of 2s, at a pressure of 800 torr (1.06 bar) and at stoichiometric conditions. The fuel was diluted in an inert gas (fuel inlet mole fraction of 0.005). Attention was paid to the formation of reaction products involved in the low temperature oxidation of n-heptane, such as olefins, cyclic ethers, aldehydes, ketones, species with two carbonyl groups (diones) and ketohydroperoxides. Diones and ketohydroperoxides are important intermediates in the low temperature oxidation of n-alkanes but their formation have rarely been reported. Significant amounts of organic acids (acetic and propanoic acids) were also observed at low temperature. The comparison of experimental data and profiles computed using an automatically generated detailed kinetic model is overall satisfactory. A route for the formation of acetic and propanoic acids was proposed. Quantum calculations were performed to refine the consumption routes of ketohydroperoxides towards diones. PMID:23712100

  12. Microstructures of capped ethylene oxide oligomers in water and n-hexane

    E-print Network

    Mangesh I. Chaudhari; Lawrence R. Pratt

    2012-09-28

    This report documents microstructural features of CH3(CH2-O-CH2)mCH3 dissolved in water and n-hexane for m = 11, 21, and 31. Probability densities for end-to-end distance, and the associated potential-of-mean-force (pmf), are more revealing of chain microstructures than are the corresponding results for the radii of gyration. For water, the pmf identifies three distinct regions: loop-closure, globule, and high-extension regions. The globule region affirms a water-swollen chain, and is not evident in the n-hexane results. Chain C-atom density profiles from the chain centroid are also different in the water and n-hexane cases. For n-hexane (but not water), the density profiles are similar for the different chain lengths when the distances are scaled by the observed ^{1/2}. For water (but not n-hexane) and the smaller chains considered, the carbon material exhibits a distinctive enhanced concentration, or internal condensation, at the centroid core of the structure.

  13. Rate-ratio asymptotic analysis of autoignition of n-heptane in laminar nonpremixed flows

    SciTech Connect

    Seshadri, K.; Peters, N.; Paczko, G.

    2006-07-15

    A rate-ratio asymptotic analysis is carried out to elucidate the mechanisms of autoignition of n-heptane (C{sub 7}H{sub 16}) in laminar, nonpremixed flows. It has been previously established that autoignition of n-heptane takes place in three distinct regimes. These regimes are called the low-temperature regime, the intermediate-temperature regime, and the high-temperature regime. The present analysis considers the high-temperature regime. A reduced chemical-kinetic mechanism made up of two global steps is used in the analysis. The reduced mechanism is deduced from a skeletal mechanism made up of 16 elementary reactions. The skeletal mechanism is derived from a short mechanism made up of 30 elementary reactions. The short mechanism is deduced from a detailed mechanism made up of 56 elementary reactions. In the reduced mechanism, the first global step represents a sequence of fast reactions starting from the rate-limiting elementary reaction between n-heptane and HO{sub 2}. In this global step C{sub 7}H{sub 16} is consumed and hydrogen peroxide (H{sub 2}O{sub 2}) is formed. The second global step represents a sequence of fast reactions starting from the rate-limiting elementary reaction in which H{sub 2}O{sub 2} is consumed and OH is formed. A key aspect of the second global step is that the sequence of fast reactions gives rise to consumption of fuel only without net consumption of H{sub 2}O{sub 2}. This makes the chemical system autocatalytic. The unsteady flamelet equations are used to predict the onset of autoignition. In the flamelet equations a conserved scalar quantity, Z, is used as the independent variable. On the oxidizer side of the mixing layer Z=0, and on the fuel side Z=1. The practical case where the temperature of the oxidizer stream, T{sub 2}, is much greater than the temperature of the fuel stream is considered. Therefore autoignition is presumed to take place close to Z=0. Balance equations are written for C{sub 7}H{sub 16} and H{sub 2}O{sub 2}. It is postulated that autoignition will take place when the gradient of mass fraction fuel with respect to Z, evaluated at Z=0, is zero. The value of T{sub 2} when autoignition takes place is obtained as a function of the strain rate. These critical conditions of autoignition obtained from asymptotic analysis agree well with those calculated using the detailed mechanism and the skeletal mechanism. (author)

  14. Some Recent Observations on the Burning of Isolated N-Heptane and Alcohol Droplets

    NASA Technical Reports Server (NTRS)

    Dryer, F. L.; Kazakov, A.; Urban, B. D.

    2001-01-01

    In a joint program involving Prof. F.A. Williams of the University of California, San Diego and Dr. V. Nayagam of the National Center for Microgravity Research on Combustion and Fluid Dynamics, the combustion of liquid fuel droplets of n-heptane, n-decane, methanol, methanol-water, ethanol and ethanol-water having initial diameters between about 1 mm and 6 mm continues to be studied. The objectives of the work are to improve fundamental knowledge of droplet combustion dynamics for pure fuels and fuel-water mixtures through microgravity experiments and theoretical analyses. The Princeton contributions to the collaborative program supports the engineering design, data analysis, and data interpretation requirements for the study of initially single component, spherically symmetric, isolated droplet combustion studies through experiments and numerical modeling. The complementary UCSD contributions apply asymptotic theoretical analyses and are described in the published literature and in a companion communication in this conference. The combined program continues to focus on analyses of results obtained from Fiber Supported Droplet Combustion (FSDC) experiments (FSDC-2, STS- 94) conducted with the above fuels in shuttle cabin air and Droplet Combustion Experiment (DCE) data obtained for unsupported and fiber supported droplets of n-heptane in Helium-Oxygen mixtures and cabin air (STS-83, STS-94). The program is preparing for a second DCE experimental mission using methanol/methanol-water as fuels and helium-oxygen-nitrogen environments. DCE-2 is to be conducted aboard the International Space Station. Emphases of recent Princeton work are on the study of simple alcohols (methanol, ethanol) and alcohol/water mixtures as fuels, with time-dependent measurements of drop size, flame-standoff, liquid-phase composition, and finally, extinction. Ground based experiments have included bench-scale studies at Princeton and collaborative experimental studies in the 2.2 second drop tower at NASA-Glenn Research Center.

  15. A comprehensive and compact n-heptane oxidation model derived using chemical lumping.

    PubMed

    Ahmed, Syed Sayeed; Mauss, Fabian; Moréac, Gladys; Zeuch, Thomas

    2007-03-01

    A detailed reaction mechanism for n-heptane oxidation has been compiled and subsequently simplified. The model is based on a kinetic model for C1-C4 fuel oxidation of Hoyermann et al. [Phys. Chem. Chem. Phys., 2004, 6, 3824] and a detailed mechanism for n-heptane oxidation developed by Curran et al. [Combust. Flame, 1998, 114, 149]. The generated mechanism is kept compact by limiting the application of the low temperature oxidation pathways to the fuel molecule. The first reaction steps and the complex low temperature paths in the oxidation process have been simplified and reorganized by linear chemical lumping. The reported procedure allows a decrease in number of species and reactions with only a minor loss of model accuracy. The simplified model is of very compact size and gives an advantageous starting point for further model reduction. By this chemically lumped general mechanism without further adjustments the large set of experimental data for the high and low temperature oxidation (ignition delay times, species concentration profiles, heat release and engine pressure profiles, flame speeds and flame structure data) for conditions ranging from very low to high temperatures (550-2300 K), very lean to extremely fuel rich (0.22 < phi < 3) mixtures and pressures between 1 and 42 bar is consistently described providing a basis for reliable predictions for future applications, (i) building reaction mechanisms for similar but chemically more complex fuels (e.g. iso-octane, n-decane,...) and (ii) calculating complex flow fields ("fluid dynamics") after further simplification with advanced reduction tools. PMID:17311154

  16. EFFECTS OF EQUIVALENCE RATIO ON SPECIES AND SOOT CONCENTRATIONS IN PREMIXED N-HEPTANE FLAMES. (R828193)

    EPA Science Inventory

    The micro-structure of laminar premixed, atmospheric-pressure, fuel-rich flames of n-heptane/oxygen/argon has been studied at two equivalence ratios (C/O = 0.63 and C/O = 0.67). A heated quartz microprobe coupled to an online gas chromatography/mass spectrometry (HP 5890 Serie...

  17. KINETICS AND SELECTIVITY OF DEEP CATALYTIC OXIDATION OF N-HEXANE AND BENZENE

    EPA Science Inventory

    Deep (complete) catalytic combustion (oxidation) of volatile organic compounds (VOCs) is emerging as an important emission control technique. A fundamental study was carried out for low-temperature deep oxidation of n-hexane and benzene over a 0.1% Pt, 3% Ni/gamma-Al2O3 catalyst....

  18. Decomposition of multilayer benzene and n-hexane films on vanadium.

    PubMed

    Souda, Ryutaro

    2015-09-21

    Reactions of multilayer hydrocarbon films with a polycrystalline V substrate have been investigated using temperature-programmed desorption and time-of-flight secondary ion mass spectrometry. Most of the benzene molecules were dissociated on V, as evidenced by the strong depression in the thermal desorption yields of physisorbed species at 150 K. The reaction products dehydrogenated gradually after the multilayer film disappeared from the surface. Large amount of oxygen was needed to passivate the benzene decomposition on V. These behaviors indicate that the subsurface sites of V play a role in multilayer benzene decomposition. Decomposition of the n-hexane multilayer films is manifested by the desorption of methane at 105 K and gradual hydrogen desorption starting at this temperature, indicating that C-C bond scission precedes C-H bond cleavage. The n-hexane dissociation temperature is considerably lower than the thermal desorption temperature of the physisorbed species (140 K). The n-hexane multilayer morphology changes at the decomposition temperature, suggesting that a liquid-like phase formed after crystallization plays a role in the low-temperature decomposition of n-hexane. PMID:26267456

  19. Communication: Molecular dynamics and 1H NMR of n-hexane in liquid crystals

    NASA Astrophysics Data System (ADS)

    Weber, Adrian C. J.; Burnell, E. Elliott; Meerts, W. Leo; de Lange, Cornelis A.; Dong, Ronald Y.; Muccioli, Luca; Pizzirusso, Antonio; Zannoni, Claudio

    2015-07-01

    The NMR spectrum of n-hexane orientationally ordered in the nematic liquid crystal ZLI-1132 is analysed using covariance matrix adaptation evolution strategy (CMA-ES). The spectrum contains over 150 000 transitions, with many sharp features appearing above a broad, underlying background signal that results from the plethora of overlapping transitions from the n-hexane as well as from the liquid crystal. The CMA-ES requires initial search ranges for NMR spectral parameters, notably the direct dipolar couplings. Several sets of such ranges were utilized, including three from MD simulations and others from the modified chord model that is specifically designed to predict hydrocarbon-chain dipolar couplings. In the end, only inaccurate dipolar couplings from an earlier study utilizing proton-proton double quantum 2D-NMR techniques on partially deuterated n-hexane provided the necessary estimates. The precise set of dipolar couplings obtained can now be used to investigate conformational averaging of n-hexane in a nematic environment.

  20. An Experimental Study of n-Heptane and JP-7 Extinction Limits in an Opposed Jet Burner

    NASA Technical Reports Server (NTRS)

    Convery, Janet L.; Pellett, Gerald L.; O'Brien, Walter F., Jr.; Wilson, Lloyd G.; Williams, John

    2005-01-01

    Propulsion engine combustor design and analysis requires experimentally verified data on the chemical kinetics of fuel. Among the important data is the combustion extinction limit as measured by observed maximum flame strain rate. The extinction limit relates to the ability to maintain a flame in a combustor during operation. Extinction limit data can be obtained for a given fuel by means of a laminar flame experiment using an opposed jet burner (OJB). Laminar extinction limit data can be applied to the turbulent application of a combustor via laminar flamelet modeling. The OJB consists of two axi-symmetric tubes (one for fuel and one for oxidizer), which produce a flat, disk-like counter-flow diffusion flame. This paper presents results of experiments to measure extinction limits for n-heptane and the military specification fuel JP-7, obtained from an OJB. JP-7 is an Air Force-developed fuel that continues to be important in the area of hypersonics. Because of its distinct properties it is currently the hydrocarbon fuel of choice for use in Scramjet engines. This study provides much-desired data for JP-7, for which very little information previously existed. The interest in n-heptane is twofold. First, there has been a significant amount of previous extinction limit study and resulting data with this fuel. Second, n-heptane (C7H16) is a pure substance, and therefore does not vary in composition as does JP-7, which is a mixture of several different hydrocarbons. These two facts allow for a baseline to be established by comparing the new OJB results to those previously taken. Additionally, the data set for n-heptane, which previously existed for mixtures up to 26 mole percent in nitrogen, is completed up to 100% n-heptane. The extinction limit data for the two fuels are compared, and complete experimental results are included.

  1. Adsorption from n-heptane/benzene liquid mixture on acid leached bentonite powders

    NASA Astrophysics Data System (ADS)

    Sar?kaya, Yüksel; Baykal, Mehmet; Önal, Mü?erref; Yener, Nilgün

    2013-10-01

    In this study, adsorption excess isotherms of n-heptane/benzene liquid mixture on hydrochloric acid leached bentonite powders were determined. Adsorptions were conducted at 25 °C for 48 h. Experimental results were evaluated with both Schay-Nagy (SN) and Everett (E) methods. Specific surface areas (SSN and SE) of the powders were calculated regarding monolayer adsorption capacity of the preferentially adsorbed benzene. Adsorption equilibrium constants (K ? 1) were obtained by the E-method. The SE and SSN values are closed to each other. SE-values were found much lower than the corresponding Brunauer, Emmett and Teller (BET)-values. This difference was discussed with respect to the interaction of adsorbed molecules with solid surface, their collision diameter, molar cross sectional surface area and orientation in dense monolayer. Even the maximum for the SE was not associated with the maxima for K and nanopore volume (V), their values changed approximately parallel to each other with respect to the HCl% by the leaching.

  2. Inhalation developmental toxicology studies: Teratology study of n-hexane in rats: Final report

    SciTech Connect

    Mast, T.J.

    1987-12-01

    The straight chain hydrocarbon, n-hexane, is a volatile, ubiquitous solvent used in industrial, academic, and smaller commercial environments. The significant opportunity for women of child-bearing age to be exposed to this chemical prompted the undertaking of a study to assess the developmental toxicity of n-hexane in an animal model. Timed-pregnant (30 animals per group) and virgin (10 animals per group) Sprague-Dawley rats were exposed to 0 (filtered air), 200, 1000, and 5000 ppM n-hexane (99.9% purity) vapor in inhalation chambers for 20 h/day for a period of 14 consecutive days. Sperm-positive females were exposed for 6 to 19 days of gestation (dg) and virgins were exposed concurrently for 14 consecutive days. The day of sperm detection was designated as 0 dg for mated females. Adult female body weights were monitored prior to, throughout the exposure period, and at sacrifice. Uterine, placental, and fetal body weights were obtained for gravid females at sacrifice. Implants were enumerated and their status recorded as live fetus, early or late resorption, or dead. Live fetuses were sexed and examined for gross, visceral, skeletal, and soft-tissue craniofacial defects. 16 refs., 3 figs., 7 tabs.

  3. Inhalation developmental toxicology studies: Teratology study of n-hexane in mice: Final report

    SciTech Connect

    Mast, T.J.; Decker, J.R.; Stoney, K.H.; Westerberg, R.B.; Evanoff, J.J.; Rommereim, R.L.; Weigel, R.J.

    1988-05-01

    Gestational exposure to n-hexane resulted in an increase in the number of resorbed fetuses for exposure groups relative to the control group; however, the increases were not directly correlated to exposure concentration. The differences were statistically significant for the 200-ppM with respect to total intrauterine death (early plus late resorptions), and with respect to late resorptions for the 5000-ppM group. A small, but statistically significant, reduction in female (but not male) fetal body weight relative to the control group was observed at the 5000-ppM exposure level. There were no exposure-related increases in any individual fetal malformation or variation, nor was there any increase in the incidence of combined malformations or variations. Gestational exposure of CD-1 mice to n-hexane vapors appeared to cause a degree of concentration-related developmental toxicity in the absence of overt maternal toxicity, but the test material was not found to be teratogenic. This developmental toxicity was manifested as an increase in the number of resorptions per litter for all exposure levels, and as a decrease in the uterine: extra-gestational weight gain ratio at the 5000-ppM exposure level. Because of the significant increase in the number of resorptions at the 200-ppM exposure level, a no observable effect level (NOEL) for developmental toxicity was not established for exposure of mice to 200, 1000 or 5000-ppM n-hexane vapors. 21 refs., 3 figs., 9 tabs.

  4. Kinetic modeling of autoignition of higher hydrocarbons: n-heptane, n-octane and iso-octane

    SciTech Connect

    Westbrook, C.K.; Pitz, W.J.

    1986-08-01

    In the present paper, the construction of reaction mechanisms for larger fuel molecules is described, drawing heavily on experience and trends established in previous studies of smaller fuel molecules. Sensitivity analysis shows which classes of reaction steps are likely to have the greatest influence on computed results and for which additional experimental information is needed. This process is illustrated for the cases of n-heptane, n-octane, and iso-octane. N-heptane and iso-octane are of interest since they are the reference fuels defining octane number, having octane numbers of 0 and 100, respectively. N-octane is included since it can be compared with n-heptane to illustrate the importance of fuel molecule size with the structure unchanged, and it can be compared with iso-octane to show the influence of molecular structure with molecular size unchanged. Computed results under shock tube and under internal combustion engine conditions will be described to demonstrate how initial pressure, temperature, fuel type, fuel structure, and other important parameters affect the rates of autoignition. These differences will be interpreted in terms of the detailed kinetic reaction mechanism, and strategies for modifying autoignition rates will be discussed. 27 refs., 4 figs., 1 tab.

  5. A Model of Reduced Kinetics for Alkane Oxidation Using Constituents and Species for N-Heptane

    NASA Technical Reports Server (NTRS)

    Harstad, Kenneth G.; Bellan, Josette

    2011-01-01

    The reduction of elementary or skeletal oxidation kinetics to a subgroup of tractable reactions for inclusion in turbulent combustion codes has been the subject of numerous studies. The skeletal mechanism is obtained from the elementary mechanism by removing from it reactions that are considered negligible for the intent of the specific study considered. As of now, there are many chemical reduction methodologies. A methodology for deriving a reduced kinetic mechanism for alkane oxidation is described and applied to n-heptane. The model is based on partitioning the species of the skeletal kinetic mechanism into lights, defined as those having a carbon number smaller than 3, and heavies, which are the complement of the species ensemble. For modeling purposes, the heavy species are mathematically decomposed into constituents, which are similar but not identical to groups in the group additivity theory. From analysis of the LLNL (Lawrence Livermore National Laboratory) skeletal mechanism in conjunction with CHEMKIN II, it is shown that a similarity variable can be formed such that the appropriately non-dimensionalized global constituent molar density exhibits a self-similar behavior over a very wide range of equivalence ratios, initial pressures and initial temperatures that is of interest for predicting n-heptane oxidation. Furthermore, the oxygen and water molar densities are shown to display a quasi-linear behavior with respect to the similarity variable. The light species ensemble is partitioned into quasi-steady and unsteady species. The reduced model is based on concepts consistent with those of Large Eddy Simulation (LES) in which functional forms are used to replace the small scales eliminated through filtering of the governing equations; in LES, these small scales are unimportant as far as the overwhelming part of dynamic energy is concerned. Here, the scales thought unimportant for recovering the thermodynamic energy are removed. The concept is tested by using tabular information from the LLNL skeletal mechanism in conjunction with CHEMKIN II utilized as surrogate ideal functions replacing the necessary functional forms. The test reveals that the similarity concept is indeed justified and that the combustion temperature is well predicted, but that the ignition time is over-predicted, a fact traced to neglecting a detailed description of the processes leading to the heavies chemical decomposition. To palliate this deficiency, functional modeling is incorporated into this conceptual reduction in addition to the modeling the evolution of the global constituent molar density, the enthalpy evolution of the heavies, the contribution to the reaction rate of the unsteady lights from other light species and from the heavies, the molar density evolution of oxygen and water, and the mole fractions of the quasisteady light species. The model is compact in that there are only nine species-related progress variables. Results are presented showing the performance of the model for predicting the temperature and species evolution. The model reproduces the ignition time over a wide range of equivalence ratios, initial pressure, and initial temperature.

  6. Some Recent Observations on the Burning of Isolated N-Heptane and Alcohol Droplets

    NASA Technical Reports Server (NTRS)

    Dryer, F. L.

    1999-01-01

    In a joint program involving Prof F.A. Williams of the University of California, San Diego and Dr. Vedha Nayagam of the National Center for Microgravity Research on Fluid and Combustion, the combustion of liquid fuel droplets having initial diameters between about 1 mm and 6 mm is being studied. The objectives of the work are to improve fundamental knowledge of droplet combustion dynamics through microgravity experiments and theoretical analyses. The Princeton contributions to the collaborative program supports the engineering design, data analysis, and data interpretation requirements for the study of initially single component, spherically symmetric, isolated droplet combustion studies through experiments and numerical modeling. The complementary UCSD contributions apply asymptotic theoretical analyses and are described in the published literature and in a companion communication in this volume. Emphases of the Princeton work are on the study of simple alcohols (methanol, ethanol), alcohol/water mixtures, and pure alkanes (n-heptane, n-decane) as fuels, with time dependent measurements of drop size, flame-stand-off, liquid-phase composition, and finally, extinction. Ground based experiments have included bench-scale studies at Princeton and collaborative experimental studies in the 2.2 and 5.18 second drop towers at NASA-Glenn Research Center. Spacelab studies have included fiber-supported droplet combustion (FSDC) experiments in the Glovebox facility with accompanying numerical analyses. Experiments include FSDC-1, performed on the USML-2 mission in October, 1995 (STS-73) and FSDC-2, on the second flight of the MSL-1 mission in July, 1997 (STS-94).

  7. In vitro antioxidant activity and HPTLC determination of n-hexane extract of Emilia sonchifolia (L.)DC.

    PubMed Central

    Sophia, D.; Ragavendran, P.; Arulraj, C.; Gopalakrishnan, V. K.

    2011-01-01

    The free radical scavenging activities of n-hexane extract of the whole plant of Emilia sonchifolia was evaluated by employing various in vitro assay systems like DPPH radical scavenging activity, superoxide radical scavenging activity and hydrogen peroxide scavenging activity with IC50 values 180, 160 and 160 ?g/ml respectively. The results of the study indicate that the n-hexane extract of the whole plant of Emilia sonchifolia possess a significant scavenging effect with increasing concentrations probably due to its antioxidant potential. High performance thin layer chromatography (HPTLC) analysis in the n-hexane extract of Emilia sonchifolia showed the presence of terpenoids which probably may be responsible for the antioxidant activity. Thus, n-hexane extract of Emilia sonchifolia can be used potentially as a bioactive source of natural antioxidants due to the presence of terpenoids in it PMID:24826021

  8. Adsorption of nitrogen, neopentane, n-hexane, benzene and methanol for the evaluation of pore sizes in

    E-print Network

    Muzzio, Fernando J.

    Adsorption of nitrogen, neopentane, n-hexane, benzene and methanol for the evaluation of pore sizes-hexane, benzene and methanol adsorption isotherms were determined on ®ve samples of silica grade MCM-41

  9. N-hexane neuropathy with vertigo and cold allodynia in a silk screen printer: A case study.

    PubMed

    Pradhan, Sunil; Tandon, Ruchika

    2015-01-01

    N-hexane neuropathy is an occupational disease caused by exposure to n-hexane, which is used as a solvent in silk screen printing. Here, we describe a 35-year-old man, a silk screen printer by profession, who presented with dizziness, distal swelling of both lower limbs for 10 months and tingling and burning sensation in both feet for 9.5 months along with cold allodynia. The patient had normal results of a motor and sensory system examination, apart from an impaired temperature sense. Nerve conduction tests showed a conduction block in bilateral common peroneal nerves and absence of conduction in bilateral sural nerves. These symptoms resolved when further exposure to n-hexane was ceased but cold allodynia remained. Thus, cold allodynia and impaired temperature sense can be a manifestation of n-hexane neuropathy. Hence, abnormalities on nerve conduction studies can be detected in n-hexane neuropathy patients, even before clinical examination detects any such abnormalities. In the case of the patients presenting with sensory motor neuropathy, history of occupational exposure to n-hexane becomes important, as the sooner the disease is detected, the better the chances of recovery. PMID:26224503

  10. Molecular dynamics simulations of n-hexane at 1-butyl-3-methylimidazolium bis(trifluoromethylsulfonyl) imide interface

    SciTech Connect

    Lisal, Martin; Izak, Pavel

    2013-07-07

    Molecular dynamics simulations of n-hexane adsorbed onto the interface of 1-butyl-3-methylimidazolium bis(trifluoromethylsulfonyl) imide ([bmim][Tf{sub 2}N]) are performed at three n-hexane surface densities, ranged from 0.7 to 2.3 {mu}mol/m{sup 2} at 300 K. For [bmim][Tf{sub 2}N] room-temperature ionic liquid, we use a non-polarizable all-atom force field with the partial atomic charges based on ab initio calculations for the isolated ion pair. The net charges of the ions are {+-}0.89e, which mimics the anion to cation charge transfer and polarization effects. The OPLS-AA force field is employed for modeling of n-hexane. The surface tension is computed using the mechanical route and its value decreases with increase of the n-hexane surface density. The [bmim][Tf{sub 2}N]/n-hexane interface is analyzed using the intrinsic method, and the structural and dynamic properties of the interfacial, sub-interfacial, and central layers are computed. We determine the surface roughness, global and intrinsic density profiles, and orientation ordering of the molecules to describe the structure of the interface. We further compute the survival probability, normal and lateral self-diffusion coefficients, and re-orientation correlation functions to elucidate the effects of n-hexane on dynamics of the cations and anions in the layers.

  11. Ignition of turbulent swirling n-heptane spray flames using single and multiple sparks

    SciTech Connect

    Marchionea, T.; Ahmeda, S.F.; Mastorakos, E.

    2009-01-15

    This paper examines ignition processes of an n-heptane spray in a flow typical of a liquid-fuelled burner. The spray is created by a hollow-cone pressure atomiser placed in the centre of a bluff body, around which swirling air induces a strong recirculation zone. Ignition was achieved by single small sparks of short duration (2 mm; 0.5 ms), located at various places inside the flow so as to identify the most ignitable regions, or larger sparks of longer duration (5 mm; 8 ms) repeated at 100 Hz, located close to the combustion chamber enclosure so as to mimic the placement and characteristics of a gas turbine combustor surface igniter. The air and droplet velocities, the droplet diameter, and the total (i.e. liquid plus vapour) equivalence ratio were measured in inert flow by phase Doppler anemometry and sampling respectively. Fast camera imaging suggested that successful ignition events were associated with flamelets that propagated back towards the spray nozzle. Measurements of ignition probability with the single spark showed that localised ignition inside the spray is more likely to result in successful flame establishment when the spark is located in a region of negative velocity, relatively small droplet Sauter mean diameter, and mean equivalence ratio within the flammability limits. Ignition with the single spark was not possible at the location where the multiple spark experiments were performed. For those, the multiple spark sequence lasted approximately 1 to 5 s. It was found that a long spark sequence increases the ignition efficiency, which reached a maximum of 100% at the axial distance where the recirculation zone had maximum width. Ignition was not feasible with the spark downstream of about two burner diameters. Visualisation showed that small flame kernels emanate very often from the spark, which can be stretched as far as 20 mm from the electrodes by the turbulent velocity fluctuations. These kernels survive very little time. Successful overall ignition occurs at a random time from the spark initiation and, as in the case of the single spark, success is associated with kernels that move without getting extinguished towards the bluff body. The results demonstrate that the energy deposited by multiple sparks and spark stretching in a turbulent flow can have a spatially far-reaching effect to initiate combustion. (author)

  12. Cobalt pivalate complex as a catalyst for liquid phase oxidation of n-hexane

    NASA Astrophysics Data System (ADS)

    Moskovskaya, I. F.; Maerle, A. A.; Shvydkiy, N. V.; Romanovsky, B. V.; Ivanova, I. I.

    2015-09-01

    Catalytic properties of cobalt(II) pivalate complex as both individual and supported on mesoporous molecular sieves Si-KIT-6, Al-KIT-6, and Ce-KIT-6 were investigated in liquid-phase oxidation of n-hexane with molecular oxygen. This complex was shown to be an active and selective catalyst for the oxidation of n-C6H14 into C1-C4 carboxylic acids. The activity of Co(II) pivalate remains practically unchanged on heterogenizing the complex on molecular sieve supports. At the same time, its selectivity and resistance towards an oxidative degradation are slightly increased.

  13. Monte Carlo versus molecular dynamics simulations in heterogeneous systems: an application to the n-pentane liquid-vapor interface.

    PubMed

    Goujon, Florent; Malfreyt, Patrice; Simon, Jean-Marc; Boutin, Anne; Rousseau, Bernard; Fuchs, Alain H

    2004-12-22

    The Monte Carlo (MC) and molecular dynamics (MD) methodologies are now well established for computing equilibrium properties in homogeneous fluids. This is not yet the case for the direct simulation of two-phase systems, which exhibit nonuniformity of the density distribution across the interface. We have performed direct MC and MD simulations of the liquid-gas interface of n-pentane using a standard force-field model. We obtained density and pressure components profiles along the direction normal to the interface that can be very different, depending on the truncation and long range correction strategies. We discuss the influence on predicted properties of different potential truncation schemes implemented in both MC and MD simulations. We show that the MD and MC profiles can be made in agreement by using a Lennard-Jones potential truncated via a polynomial function that makes the first and second derivatives of the potential continuous at the cutoff distance. In this case however, the predicted thermodynamic properties (phase envelope, surface tension) deviate from experiments, because of the changes made in the potential. A further readjustment of the potential parameters is needed if one wants to use this method. We conclude that a straightforward use of bulk phase force fields in MD simulations may lead to some physical inconsistencies when computing interfacial properties. PMID:15606277

  14. Experimental study and chemical analysis of n-heptane homogeneous charge compression ignition combustion with port injection of reaction inhibitors

    SciTech Connect

    Lue, Xingcai; Ji, Libin; Zu, Linlin; Hou, Yuchun; Huang, Cheng; Huang, Zhen

    2007-05-15

    The control of ignition timing in the homogeneous charge compression ignition (HCCI) of n-heptane by port injection of reaction inhibitors was studied in a single-cylinder engine. Four suppression additives, methanol, ethanol, isopropanol, and methyl tert-butyl ether (MTBE), were used in the experiments. The effectiveness of inhibition of HCCI combustion with various additives was compared under the same equivalence ratio of total fuel and partial equivalence ratio of n-heptane. The experimental results show that the suppression effectiveness increases in the order MTBE < isopropanol << ethanol < methanol. But ethanol is the best additive when the operating ranges, indicated thermal efficiency, and emissions are considered. For ethanol/n-heptane HCCI combustion, partial combustion may be observed when the mole ratio of ethanol to that of total fuel is larger than 0.20; misfires occur when the mole ratio of ethanol to that of total fuel larger than 0.25. Moreover, CO emissions strongly depend on the maximum combustion temperature, while HC emissions are mainly dominated by the mole ratio of ethanol to that of total fuel. To obtain chemical mechanistic informations relevant to the ignition behavior, detailed chemical kinetic analysis was conducted. The simulated results also confirmed the retarding of the ignition timing by ethanol addition. In addition, it can be found from the simulation that HCHO, CO, and C{sub 2}H{sub 5}OH could not be oxidized completely and are maintained at high levels if the partial combustion or misfire occurs (for example, for leaner fuel/air mixture). (author)

  15. Simulation of auto-ignition of iso-octane and n-heptane in an internal combustion engine

    SciTech Connect

    Basevich, V.Ya.; Belyaev, A.A.; Brandshteter, V.

    1994-05-01

    A detailed kinetic mechanism is proposed for the oxidation of iso-octane, n-heptane, and mixtures of them in air (number of particles 43, number of reactions 284), which satisfactorily describes the distinctive features of low-temperature and high-temperature oxidation at an initial temperature of 1200 K, pressure of 15-40 absolute atmospheres or higher, and a fuel excess ratio of 0.5-2. The abbreviated mechanisms obtained to describe the auto-ignition of fuel with an octane number of 90 involve 27 particles (38 reactions) and 18 particles (22 reactions).

  16. n-Hexane hydro-isomerization over promoted Pd/HZSM-5 catalysts

    NASA Astrophysics Data System (ADS)

    Thoa Dao, Thi Kim; Loc Luu, Cam

    2015-09-01

    A series of Pd/HZSM-5 catalysts modified by various metallic species, including Co, Ni, Fe, Re, and Cu, was prepared by sequential impregnation. Contents of Pd and second metals in modified catalysts were 0.8 and 1.0 wt%, respectively. Physico-chemical characteristics of catalysts were investigated by nitrogen physi-sorption (BET), x-ray diffraction (XRD), transmission electron microscopy (TEM), ammonia temperature programmed desorption (NH3-TPD), temperature programmed reduction (TPR) and hydrogen pulse chemisorption (HPC). Coke formation was studied by the method of thermogravimetric analysis (TGA). The activities of catalysts in n-hexane isomerization were studied in a micro-flow reactor under atmospheric pressure at 250 °C, and molar ratio of H2: n-hexane of 5.92. It was found that Co, Ni, Fe, and Re additives exhibited geometric and electronic effects toward Pd/HZSM-5 catalyst, leading to an enhancement of its activity and stability. On the contrary, Cu additive caused Pd/HZSM-5 to become poorer in activity and stability.

  17. Hydraulic Transport Across Hydrophilic and Hydrophobic Nanopores: Flow Experiments with Water and n-Hexane

    E-print Network

    Simon Gruener; Dirk Wallacher; Stefanie Greulich; Mark Busch; Patrick Huber

    2015-12-12

    We experimentally explore pressure-driven flow of water and n-hexane across nanoporous silica (Vycor glass monoliths with 7 or 10 nm pore diameters, respectively) as a function of temperature and surface functionalization (native and silanized glass surfaces). Hydraulic flow rates are measured by applying hydrostatic pressures via inert gases (argon and helium, pressurized up to 70 bar) on the upstream side in a capacitor-based membrane permeability setup. For the native, hydrophilic silica walls, the measured hydraulic permeabilities can be quantitatively accounted for by bulk fluidity provided we assume a sticking boundary layer, i.e. a negative velocity slip length of molecular dimensions. The thickness of this boundary layer is discussed with regard to previous capillarity-driven flow experiments (spontaneous imbibition) and with regard to velocity slippage at the pore walls resulting from dissolved gas. Water flow across the silanized, hydrophobic nanopores is blocked up to a hydrostatic pressure of at least 70 bar. The absence of a sticking boundary layer quantitatively accounts for an enhanced n-hexane permeability in the hydrophobic compared to the hydrophilic nanopores.

  18. Hydraulic Transport Across Hydrophilic and Hydrophobic Nanopores: Flow Experiments with Water and n-Hexane

    E-print Network

    Gruener, Simon; Greulich, Stefanie; Busch, Mark; Huber, Patrick

    2015-01-01

    We experimentally explore pressure-driven flow of water and n-hexane across nanoporous silica (Vycor glass monoliths with 7 or 10 nm pore diameters, respectively) as a function of temperature and surface functionalization (native and silanized glass surfaces). Hydraulic flow rates are measured by applying hydrostatic pressures via inert gases (argon and helium, pressurized up to 70 bar) on the upstream side in a capacitor-based membrane permeability setup. For the native, hydrophilic silica walls, the measured hydraulic permeabilities can be quantitatively accounted for by bulk fluidity provided we assume a sticking boundary layer, i.e. a negative velocity slip length of molecular dimensions. The thickness of this boundary layer is discussed with regard to previous capillarity-driven flow experiments (spontaneous imbibition) and with regard to velocity slippage at the pore walls resulting from dissolved gas. Water flow across the silanized, hydrophobic nanopores is blocked up to a hydrostatic pressure of at l...

  19. H{sub 2}O{sub 2} enhanced thermal oxidation of n-heptane and chlorobenzene

    SciTech Connect

    Geiger, C.L.; Clausen, C.A.; Martinez, A.; Cooper, C.D.

    1995-12-01

    The destruction of certain volatile organic compounds (VOCs) by incineration requires high temperatures and long residence times. The oxidation process occurs by a complex series of reactions initiated and propagated by free radicals. It was postulated that the addition of hydrogen peroxide to a heated stream of VOCs in air would enhance the kinetics of thermal oxidation. In this work, the VOCs studied include n-heptane and chlorobenzene. Results show that H{sub 2}O, is effective in enhancing the thermal destruction of both compounds. Computer kinetic modeling was done using the Chemkin II program package and the predicted products of incomplete combustion (PICs) were compared with those found experimentally using GC and GC-MS analysis. Although the model does not accurately predict PICs for both parent compounds, the experimental data for further adjustments of the model and a better understanding of what reactions may be of importance in the proposed mechanisms.

  20. A molecular ``phase ordering'' phase transition leading to a modulated aperiodic composite in n-heptane/urea

    NASA Astrophysics Data System (ADS)

    Mariette, C.; Huard, M.; Rabiller, P.; Nichols, Shane M.; Ecolivet, C.; Janssen, Ted; Alquist, Keith E.; Hollingsworth, Mark D.; Toudic, B.

    2012-03-01

    n-Heptane/urea is an aperiodic inclusion compound in which the ratio of host and guest repeats along the channel axis is very close to unity and is found to have a constant value (0.981) from 280 K to 90 K. Below 280 K, two phase transitions are observed. The first (Tc1 = 145 K) is a ferroelastic phase transition that generates superstructure reflections for the host while leaving the guest with 1D order. The second (Tc2 = 130 K) is a "phase ordering" transition to a four-dimensional structure (P2111(0??)) with pronounced host-guest intermodulation and a temperature dependent phase shift between guests in adjacent channels.

  1. A comprehensive skeletal mechanism for the oxidation of n-heptane generated by chemistry-guided reduction

    SciTech Connect

    Zeuch, Thomas; Moreac, Gladys; Ahmed, Syed Sayeed; Mauss, Fabian

    2008-12-15

    Applied to the primary reference fuel n-heptane, we present the chemistry-guided reduction (CGR) formalism for generating kinetic hydrocarbon oxidation models. The approach is based on chemical lumping and species removal with the necessity analysis method, a combined reaction flow and sensitivity analysis. Independent of the fuel size, the CGR formalism generates very compact submodels for the alkane low-temperature oxidation and provides a general concept for the development of compact oxidation models for large model fuel components such as n-decane and n-tetradecane. A defined sequence of simplification steps, consisting of the compilation of a compact detailed chemical model, the application of linear chemical lumping, and finally species removal based on species necessity values, allows a significantly increased degree of reduction compared to the simple application of the necessity analysis, previously published species, or reaction removal methods. The skeletal model derived by this procedure consists of 110 species and 1170 forward and backward reactions and is validated against the full range of combustion conditions including low and high temperatures, fuel-lean and fuel-rich mixtures, pressures between 1 and 40 bar, and local (species concentration profiles in flames, plug flow and jet-stirred reactors, and reaction sensitivity coefficients) and global parameters (ignition delay times in shock tube experiments, ignition timing in a HCCI engine, and flame speeds). The species removal is based on calculations using a minimum number of parameter configurations, but complemented by a very broad parameter variation in the process of compiling the kinetic input data. We further demonstrate that the inclusion of sensitivity coefficients in the validation process allows efficient control of the reduction process. Additionally, a compact high-temperature n-heptane oxidation model of 47 species and 468 reactions was generated by the application of necessity analysis to the skeletal mechanism. (author)

  2. THE JOURNAL OF CHEMICAL PHYSICS 139, 014704 (2013) Molecular dynamics simulations of n-hexane at 1-butyl-3-

    E-print Network

    Lisal, Martin

    2013-01-01

    of the ions are ±0.89e, which mimics the anion to cation charge transfer and polarization effects. The OPLS, good conductivity, and good solubility of so- lutes. In addition, the variety of cations and anions, and re-orientation correlation functions to elucidate the effects of n-hexane on dynamics of the cations

  3. Solid - Liquid Phase Transition in a Gibbs Monolayer of Melissic Acid at the n-Hexane - Water Interface

    E-print Network

    Aleksey M. Tikhonov

    2015-12-02

    A sharp phase transition from a crystalline state with the area per molecule A = (17 +/- 1) Angstrom^2 to a liquid state with A = (23 +/- 1) Angstrom^2 at the n-hexane - water interface in a Gibbs monolayer of melissic acid has been revealed in data of X-ray reflectometry with the use of synchrotron radiation.

  4. A model of reduced kinetics for alkane oxidation using constituents and species: Proof of concept for n-heptane

    SciTech Connect

    Harstad, Kenneth; Bellan, Josette

    2010-08-15

    A methodology for deriving a reduced kinetic mechanism for alkane oxidation is described and applied to n-heptane. The model is based on partitioning the species of the skeletal kinetic mechanism into lights, defined as those having a carbon number smaller than 3, and heavies, which are the complement in the species ensemble. For modeling purposes, the heavy species are mathematically decomposed into constituents, which are similar but not identical to groups in the group additivity theory. From analysis of the LLNL skeletal mechanism in conjunction with CHEMKIN II, it is shown that a similarity variable can be formed such that the appropriately scaled global constituent molar density exhibits a self-similar behavior over a very wide range of equivalence ratios, initial pressures and initial temperatures that is of interest for predicting n-heptane oxidation. Furthermore, the oxygen and water molar densities are shown to display a quasi-linear behavior with respect to the similarity variable. The light species ensemble is partitioned into quasi-steady and unsteady species. The concept is tested by using tabular information from the LLNL skeletal mechanism in conjunction with CHEMKIN II. The test reveals that the similarity concept is indeed justified and that the combustion temperature is well predicted, but that the ignition time is overpredicted. To palliate this deficiency, functional modeling is incorporated into our conceptual reduction. Due to the reduction process, models are also included for the global constituent molar density, the kinetics-induced enthalpy evolution of the heavy species, the contribution to the reaction rate of the unsteady lights from the heavies, the molar density evolution of oxygen and water, the mole fractions of the quasi-steady light species and the mean molar heat capacity of the heavy species. The model is compact in that there are only nine species-related progress variables. Results are presented comparing the performance of the model for predicting the temperature and species evolution with that of the skeletal mechanism. The model reproduces the ignition time over a wide range of equivalence ratios, initial pressure and initial temperature. (author)

  5. Preferred orientation of n-hexane crystallized in silicon nanochannels: A combined x-ray diffraction and sorption isotherm study

    E-print Network

    Henschel, Anke; Hofmann, Tommy; Knorr, Klaus; Huber, Patrick; 10.1103/PhysRevE.79.032601

    2009-01-01

    We present an x-ray diffraction study on n-hexane in tubular silicon channels of approximately 10 nm diameter both as a function of the filling fraction f of the channels and as a function of temperature. Upon cooling, confined n-hexane crystallizes in a triclinic phase typical of the bulk crystalline state. However, the anisotropic spatial confinement leads to a preferred orientation of the confined crystallites, where the crystallographic direction coincides with the long axis of the channels. The magnitude of this preferred orientation increases with the filling fraction, which corroborates the assumption of a Bridgman-type crystallization process being responsible for the peculiar crystalline texture. This growth process predicts for a channel-like confinement an alignment of the fastest crystallization direction parallel to the long channel axis. It is expected to be increasingly effective with the length of solidifying liquid parcels and thus with increasing f. In fact, the fastest solidification front...

  6. Linear time reduction of large kinetic mechanisms with directed relation graph: n-Heptane and iso-octane

    SciTech Connect

    Lu, Tianfeng; Law, Chung K.

    2006-01-01

    The algorithm of directed relation graph recently developed for skeletal mechanism reduction was extended to overall linear time operation, thereby greatly facilitating the computational effort in mechanism reduction, particularly for those involving large mechanisms. Together with a two-stage reduction strategy and using the kinetic responses of autoignition and perfectly stirred reactor (PSR) with extensive parametric variations as the criteria in eliminating unimportant species, a detailed 561-species n-heptane mechanism and a detailed 857-species iso-octane mechanism were successfully reduced to skeletal mechanisms consisting of 188 and 233 species, respectively. These skeletal mechanisms were demonstrated to mimic well the performance of the detailed mechanisms, not only for the autoignition and PSR systems based on which the reduced mechanisms were developed but also for the independent system of jet-stirred reactor. It was further observed that the accuracy of calculated species concentrations was equivalently bounded by the user-specified error threshold value and that the reduction time for a single reaction state is only about 50 ms for the large iso-octane mechanism.

  7. Inhalation reproductive toxicology studies: Male dominant lethal study of n-hexane in Swiss (CD-1) mice: Final report

    SciTech Connect

    Mast, T.J.; Rommereim, R.L.; Evanoff, J.J.; Sasser, L.B.; Decker, J.R.; Stoney, K.H.; Weigel, R.J.; Westerberg, R.B.

    1988-08-01

    The straight-chain hydrocarbon, n-hexane, is a volatile, ubiquitous solvent routinely used in industrial environments; consequently, the opportunity for industrial, environmental or accidental exposure to hexane vapors is significant. Although myelinated nerve tissue is the primary target organ of hexane, the testes have also been identified as being sensitive to hexacarbon exposure. The objective of this study was to evaluate male dominant lethal effects in Swiss (CD-1) mice after exposure to 0, 200, 1000, or 5000 ppM n-hexane, 20 h/day for 5 consecutive days. Each exposure concentration consisted of 30 randomly selected, proven male breeders; 4 groups. The mice were weighed just prior to the first day of exposure and at weekly intervals until sacrifice. Ten males in each dose group were sacrificed one day after the cessation of exposure, and their testes and epididymides were removed for evaluation of the germinal epithelium. The remaining male mice, 20 per group, were individually housed in hanging wire-mesh breeding cages where they were mated with unexposed, virgin females for eight weekly intervals; new females were provided each week. The mated females were sacrificed 12 days after the last day of cohabitation and their reproductive status and the number and viability of the implants were recorded. The appearance and behavior of the male mice were unremarkable throughout the study period and no evidence of n-hexane toxicity was observed. 18 refs., 3 figs., 11 tabs.

  8. Analysis of petroleum contaminated soils by spectral modeling and pure response profile recovery of n-hexane.

    PubMed

    Chakraborty, Somsubhra; Weindorf, David C; Li, Bin; Ali, Md Nasim; Majumdar, K; Ray, D P

    2014-07-01

    This pilot study compared penalized spline regression (PSR) and random forest (RF) regression using visible and near-infrared diffuse reflectance spectroscopy (VisNIR DRS) derived spectra of 164 petroleum contaminated soils after two different spectral pretreatments [first derivative (FD) and standard normal variate (SNV) followed by detrending] for rapid quantification of soil petroleum contamination. Additionally, a new analytical approach was proposed for the recovery of the pure spectral and concentration profiles of n-hexane present in the unresolved mixture of petroleum contaminated soils using multivariate curve resolution alternating least squares (MCR-ALS). The PSR model using FD spectra (r(2) = 0.87, RMSE = 0.580 log10 mg kg(-1), and residual prediction deviation = 2.78) outperformed all other models tested. Quantitative results obtained by MCR-ALS for n-hexane in presence of interferences (r(2) = 0.65 and RMSE 0.261 log10 mg kg(-1)) were comparable to those obtained using FD (PSR) model. Furthermore, MCR ALS was able to recover pure spectra of n-hexane. PMID:24686115

  9. A complex chemical kinetic mechanism for the oxidation of gasoline surrogate fuels: n heptane, iso octane and toluene - Mechanism development and validation

    E-print Network

    Da Cruz, A Pires; Anderlohr, Jörg; Bounaceur, Roda; Battin-Leclerc, Frédérique

    2009-01-01

    The development and validation against experimental results of a new gasoline surrogate complex kinetic mechanism is presented in this paper. The surrogate fuel is a ternary mixture of n heptane, iso octane and toluene. The full three components mechanism is based on existing n heptane/iso octane (gasoline PRF) and toluene mechanisms which were modified and coupled for the purpose of this work. Mechanism results are compared against available experimental data from the literature. Simulations with the PRF plus toluene mechanism show that its behavior is in agreement with experimental results for most of the tested settings. These include a wide variety of thermodynamic conditions and fuel proportions in experimental configurations such as HCCI engine experiments, rapid compression machines, a shock tube and a jet stirred reactor.

  10. Theoretical Basis for Estimated Test Times and Conditions for Drop Tower and Space-Based Droplet Burning Experiments With Methanol and N-Heptane

    NASA Technical Reports Server (NTRS)

    Marchese, Anthony J.; Dryer, Fredrick L.; Choi, Mun Y.

    1994-01-01

    In order to develop an extensive envelope of test conditions for NASA's space-based Droplet Combustion Experiment (DCE) as well those droplet experiments which can be performed using a drop tower, the transient vaporization and combustion of methanol and n-heptane droplets were simulated using a recently developed fully time-dependent, spherically symmetric droplet combustion model. The transient vaporization of methanol and n-heptane was modeled to characterize the instantaneous gas phase composition surrounding the droplet prior to the introduction of an ignition source. The results for methanol/air showed that the entire gas phase surrounding a 2 mm methanol droplet deployed in zero-g .quickly falls outside the lean flammability limit. The gas phase surrounding an identically-sized n-heptane droplet, on the other hand, remains flammable. The combustion of methanol was then modeled considering a detailed gas phase chemical kinetic mechanism (168 steps, 26 species) and the effect of the dissolution of flame-generated water into the liquid droplet. These results were used to determine the critical ignition diameter required to achieve quasi-steady droplet combustion in a given oxidizing environment. For droplet diameters greater than the critical ignition diameter, the model predicted a finite diameter at which the flame would extinguish. These extinction diameters were found to vary significantly with initial droplet diameter. This phenomenon appears to be unique to the transient heat transfer, mass transfer and chemical kinetics of the system and thus has not been reported elsewhere to date. The extinction diameter was also shown to vary significantly with the liquid phase Lewis number since the amount of water present in the droplet at extinction is largely governed by the rate at which water is transported into the droplet via mass diffusion. Finally, the numerical results for n-heptane combustion were obtained using both 2 step and 96 step semi-emperical chemical kinetic mechanisms. Neither mechanism exhibited the variation of extinction diameter with initial diameter.

  11. Studies of photoionization in liquids using a laser two-photon ionization conductivity technique. [Potoionization of pyrene, fluoranthene and TMPD in liquid n-pentane

    SciTech Connect

    Siomos, K.; Christophorou, L.G.

    1981-01-01

    One-photon ionization studies of solute molecules in a liquid medium are limited by the absorption of the host medium. A laser two-photon ionization (TPI) technique using a frequency tunable dye laser has been developed, whereby the photoionization threshold of a solute molecule was determined from the induced conductivity in the liquid medium under study due to electron-ion pair formation via two-photon ionization of the solute. The two-photon induced electron-ion current is measured as a function of the laser wavelength, lambda/sub laser/. In this paper, results are reported and discussed on the photoionization of N,N,N',N'-tetramethyl-p-phenylenediamine (TMPD), pyrene and fluoranthene in liquid n-pentane (n-Pt).

  12. Combustion Characteristics in a Non-Premixed Cool-Flame Regime of n-Heptane in Microgravity

    NASA Technical Reports Server (NTRS)

    Takahashi, Fumiaki; Katta, Viswanath R.; Hicks, Michael C.

    2015-01-01

    A series of distinct phenomena have recently been observed in single-fuel-droplet combustion tests performed on the International Space Station (ISS). This study attempts to simulate the observed flame behavior numerically using a gaseous n-heptane fuel source in zero gravity and a time-dependent axisymmetric (2D) code, which includes a detailed reaction mechanism (127 species and 1130 reactions), diffusive transport, and a radiation model (for CH4, CO, CO2, H2O, and soot). The calculated combustion characteristics depend strongly on the air velocity around the fuel source. In a near-quiescent air environment (< or = 2 mm/s), with a sufficiently large fuel injection velocity (1 cm/s), a growing spherical diffusion flame extinguishes at ˜1200 K due to radiative heat losses. This is typically followed by a transition to the low-temperature (cool-flame) regime with a reaction zone (at ˜700 K) in close proximity to the fuel source. The 'cool flame' regime is formed due to the negative temperature coefficient in the low-temperature chemistry. After a relatively long period (˜18 s) of the cool flame regime, a flash re-ignition occurs, associated with flame-edge propagation and subsequent extinction of the re-ignited flame. In a low-speed (˜3 mm/s) airstream (which simulates the slight droplet movement), the diffusion flame is enhanced upstream and experiences a local extinction downstream at ˜1200 K, followed by steady flame pulsations (˜0.4 Hz). At higher air velocities (4-10 mm/s), the locally extinguished flame becomes steady state. The present axisymmetric computational approach helps in revealing the non-premixed 'cool flame' structure and 2D flame-flow interactions observed in recent microgravity droplet combustion experiments.

  13. Hydrocarbon fuel effects in solid-oxide fuel cell operation: an experimental and modeling study of n-hexane pyrolysis.

    PubMed

    Randolph, Katie L; Dean, Anthony M

    2007-08-21

    Pyrolysis experiments of n-hexane were performed and the product distribution and fuel consumption were measured as a function of temperature. The experimental temperatures ranged from 550-675 degrees C, with a pressure of approximately 1 atm, and residence times of approximately 5 s. N-Hexane was used as a model compound to represent the linear alkanes that might be found in practical hydrocarbon fuels. Under these conditions, high fuel conversion was observed at the higher temperatures and a wide range of products were formed. The experimental observations were compared to predictions from a plug-flow model using a reaction mechanism consisting of 205 species and 1403 reactions. The hydrogen abstraction and isomerization rate coefficients in this model were based on CBS-QB3 calculations. The only model modification was adjustment of the A-factor of the initiation rates to match conversion at one temperature. This model was able to successfully predict the observed trends in both product selectivities as well as fuel conversion over the temperature range. The mechanism was also used to capture the trends previously observed in n-butane pyrolysis under similar experimental conditions. Significant differences in the sensitivity coefficients for the hexane and butane systems are discussed in terms of the competition between beta-scission and isomerization of the initial radicals formed. The kinetic model predicts that n-hexane will be completely converted within 0.1 s in the higher temperature environment ( approximately 800 degrees C) of the anode channel of a solid-oxide fuel cell (SOFC). This result clearly illustrates the need to explicitly account for gas-phase reactions in SOFC models for those cases where hydrocarbons, especially those larger than methane, are fed directly to an SOFC. PMID:17687473

  14. cis-trans photoisomerization of 1,3,5,7-octatetraene in n-hexane at 4.2 K

    PubMed Central

    Granville, Mark F.; Holtom, Gary R.; Kohler, Bryan E.

    1980-01-01

    Photoisomerization of the linear polyene 1,3,5,7-octatetraene has been observed in an n-hexane matrix maintained at the boiling point of helium. To a good approximation, only the trans,trans and cis,trans isomers participate in the photochemistry. These compounds have been unambiguously identified by comparing the observed high-resolution fluorescence spectra to those of chromatographically purified reference compounds. Although the quantum yield of this process is probably low, its microscopic rate seems to compete favorably with vibrational deactivation. PMID:16592751

  15. Light Absorption by Hydrocarbon Molecules at 3.392 ?m of He-Ne Laser

    NASA Astrophysics Data System (ADS)

    Tsuboi, Takao; Inomata, Katsumi; Tsunoda, Yutaka; Isobe, Akihito; Nagaya, Koh-ichi

    1985-01-01

    The decadic molar extinction coefficients of various hydrocarbon molecules at the wavelength of 3.392 ?m of the infrared He-Ne laser were measured at temperatures between 292 and 1100 K using the shock-tube technique. Methane, ethane, propane, n-pentane, n-hexane, n-heptane, n-octane, n-nonane, iso-octane, methanol, ethanol, butanol, acetone and benzene absorbed the laser light. No Doppler-or pressure-broadening of these molecules was observed except in the case of methane and ethane. The values of the decadic molar exctinction coefficients give information on a temperature-measurement technique which utilizes Beer-Lambert’s law.

  16. Crystallization of thin water films on graphite: Effects of n-hexane, formaldehyde, acetone, and methanol additives

    NASA Astrophysics Data System (ADS)

    Souda, Ryutaro

    2015-12-01

    Interactions of molecular additives with amorphous solid water have been investigated using time-of-flight secondary ion mass spectrometry and temperature programmed desorption. The crystallization temperature of water on a clean graphite substrate decreases from the bulk value of 160 K to 150 K when water deposition temperature increases from 20 K to 100 K. This phenomenon is induced by the formation of a specifically oriented water layer at the interface, as evidenced by that a submonolayer of n-hexane adspecies on graphite quenches this behavior. Thermal desorption spectra of additives reflect their hydration forms. The n-hexane molecules are trapped in the interior of a porous water film via hydrophobic hydration and released explosively during crystallization. The thermal desorption spectra of methanol resemble those of water from multilayer films because methanol can enter the hydrogen-bond network of water via hydrophilic hydration. The hydration of formaldehyde is hydrophobic in nature despite the presence of the polar carbonyl group. Features of both hydrophilic and hydrophobic hydrations are identifiable in acetone-water interactions; the branching ratio depends on the water preparation method and substrate.

  17. Reflectometric measurement of n-hexane adsorption on ZnO2 nanohybrid film modified by hydrophobic gold nanoparticles

    NASA Astrophysics Data System (ADS)

    Seb?k, Dániel; Csapó, Edit; Ábrahám, Nóra; Dékány, Imre

    2015-04-01

    Zinc-peroxide/poly(styrenesulfonate) nanohybrid thin films (containing 20 bilayers: [ZnO2/PSS]20, d ? 500 nm) were prepared using layer-by-layer (LbL) method. The thin film surface was functionalized by different surface modifying agents (silanes, alkylthiols and hydrophobized nanoparticles). Based on the experimental results of quartz crystal microbalance (QCM) and contact angle measurements (as prequalifications) the octanethiol covered gold nanoparticles (OT-AuNPs) were selected for further vapour adsorption studies. Reflectometric interference spectroscopy (RIfS) was used to measure n-hexane vapour adsorption on the original and modified nanohybrid films in a gas flow platform. The thin film provides only the principle of the measurement (by interference phenomenon), the selectivity and hydrophobicity is controlled and enhanced by surface functionalization (by dispersion interaction between the alkyl chains). The interference pattern shift (??) caused by the increase of the optical thickness of the thin film due to vapour adsorption was investigated. It was found that due to the surface functionalization by hydrophobic nanoparticles the effect of water vapour adsorption decreased significantly, while for n-hexane opposite tendency was observed (the effective refractive index and thus the interference pattern shift increased drastically). The correlation between QCM technique and optical method (RIfS) was specified: linear specific adsorbed amount vs. wavelength shift calibration curves were determined in the pr = 0-0.4 relative vapour pressure range. The thin film is suitable for sensorial application (e.g. volatile organic compound/VOC sensor).

  18. Preferred orientation of n-hexane crystallized in silicon nanochannels: A combined x-ray diffraction and sorption isotherm study

    E-print Network

    Anke Henschel; Pushpendra Kumar; Tommy Hofmann; Klaus Knorr; Patrick Huber

    2009-03-19

    We present an x-ray diffraction study on n-hexane in tubular silicon channels of approximately 10 nm diameter both as a function of the filling fraction f of the channels and as a function of temperature. Upon cooling, confined n-hexane crystallizes in a triclinic phase typical of the bulk crystalline state. However, the anisotropic spatial confinement leads to a preferred orientation of the confined crystallites, where the crystallographic direction coincides with the long axis of the channels. The magnitude of this preferred orientation increases with the filling fraction, which corroborates the assumption of a Bridgman-type crystallization process being responsible for the peculiar crystalline texture. This growth process predicts for a channel-like confinement an alignment of the fastest crystallization direction parallel to the long channel axis. It is expected to be increasingly effective with the length of solidifying liquid parcels and thus with increasing f. In fact, the fastest solidification front is expected to sweep over the full silicon nanochannel for f=1, in agreement with our observation of a practically perfect texture for entirely filled nanochannels.

  19. Mesoporous Aluminosilicate Catalysts for the Selective Isomerization of n-Hexane: The Roles of Surface Acidity and Platinum Metal.

    PubMed

    Musselwhite, Nathan; Na, Kyungsu; Sabyrov, Kairat; Alayoglu, Selim; Somorjai, Gabor A

    2015-08-19

    Several types of mesoporous aluminosilicates were synthesized and evaluated in the catalytic isomerization of n-hexane, both with and without Pt nanoparticles loaded into the mesopores. The materials investigated included mesoporous MFI and BEA type zeolites, MCF-17 mesoporous silica, and an aluminum modified MCF-17. The acidity of the materials was investigated through pyridine adsorption and Fourier Transform-Infrared Spectroscopy (FT-IR). It was found that the strong Brönsted acid sites in the micropores of the zeolite catalysts facilitated the cracking of hexane. However, the medium strength acid sites on the Al modified MCF-17 mesoporous silica greatly enhanced the isomerization reaction. Through the loading of different amounts of Pt into the mesopores of the Al modified MCF-17, the relationship between the metal nanoparticles and acidic sites on the support was revealed. PMID:26168190

  20. Supercritical SC-CO2 and Soxhlet n-Hexane Extract of Tunisian Opuntia ficus indica Seeds and Fatty Acids Analysis

    PubMed Central

    Yeddes, Nizar; Chérif, Jamila Kalthoum; Jrad, Amel; Barth, Danielle; Trabelsi-Ayadi, Malika

    2012-01-01

    The fatty acids profiles of Tunisian Opuntia ficus indica seeds (spiny and thornless form) were investigated. Results of supercritical carbon dioxide (SC-CO2) and soxhlet n-hexane extract were compared. Quantitatively, the better yield was obtained through soxhlet n-hexane: 10.32% (spiny) and 8.91% (thornless) against 3.4% (spiny) and 1.94% (thornless) by SC-CO2 extract (T?=?40°C, P = 180 bar, time?=?135?mn, CO2 flow rate?=?15?mL·s?1). Qualitatively, the main fatty acids components were the same for the two types of extraction. Linoleic acid was the major compound, SC-CO2:?57.60% (spiny), 59.98% (thornless), soxhlet n-hexane: 57.54% (spiny), 60.66% (thornless), followed by oleic acid, SC-CO2:?22.31% (spiny), 22.40% (thornless), soxhlet n-hexane: 25.28% (spiny), 20.58% (thornless) and palmitic acid, SC-CO2:?14.3% (spiny), 12.92% (thornless), soxhlet n-hexane: 11.33% (spiny), 13.08% (thornless). The SC-CO2 profiles fatty acids showed a richness with other minority compounds such as C20:1, C20:2, and C22.The seeds oil was highly unsaturated (US?=?4.44–5.25), and the rising temperatures donot affect the selectivity of fatty acids extract by SC-CO2: US?=?4.44 (T?=?40°C) and 4.13 (T?=?70°C). PMID:22754699

  1. A molecular dynamics study of the coupling of torsional motions to self-diffusion in liquid n-hexane

    NASA Astrophysics Data System (ADS)

    Travis, Karl P.; Brown, David; Clarke, Julian H. R.

    1995-02-01

    Dynamic coupling of molecular flexibility with self-diffusion has been studied for a model of liquid n-hexane using the technique of frozen distribution sampling (FDS) [Travis et al., J. Chem. Phys. 98, 1524 (1993)]. FDS facilitates comparison of transport properties between a liquid of flexible molecules and a liquid in which the molecular shape fluctuations are frozen in an equilibrium distribution; thus the two liquids have identical equilibrium configurational properties. The diffusion coefficient of model hexane was found to increase by a factor of ˜20 on raising the temperature from 200 and 1000 K; coupling with torsional motions enhances the diffusion coefficient by about 20% over the whole of this range. At each temperature a quantitative measure of the coupling was obtained by making comparisons with self-diffusion in a liquid for which the potential restricting torsional motion is removed—called flexane [D. Brown and J. H. R. Clarke, J. Chem. Phys. 86, 1542 (1987)]. Using FDS it was confirmed that the enhancement of the diffusion coefficient in flexane as compared to hexane arises from differences in the short time dynamics and not from differences in the static structure of the two liquids. For hexane a coupling parameter is defined which shows that the extent of dynamic coupling increases from ˜10% at 200 K and appears to have reached a maximum by 1000 K. The coupling mechanism is discussed using power spectra obtained from the relative velocities of the methylene (and methyl) groups relative to the molecular centers of mass. It is concluded that torsional oscillations mainly involving the outer dihedral angles provide the probable mechanism for the coupling.

  2. Inhalation reproductive toxicology studies: Sperm morphology study of n-hexane in B6C3F1 mice: Final report

    SciTech Connect

    Mast, T.J.; Hackett, P.L.; Decker, J.R.; Westerberg, R.B.; Sasser, L.B.; McClanahan, B.J.; Rommereim, R.L.; Evanoff, J.J.

    1988-08-01

    The straight-chain hydrocarbon, n-hexane, is a volatile, ubiquitous solvent routinely used in industrial environments. Although myelinated nerve tissue is the primary target organ of hexane, the testes have also been identified as being sensitive to hexacarbon exposure. The objective of this study was to evaluate the epididymal sperm morphology of male B6D3F1 mice 5 weeks after exposure to 0, 200, 1000, or 5000 ppM n-hexane, 20 h/day for 5 consecutive days. Two concurrent positive control groups of animals were injected intraperitoneally with either 200 or 250 mg/kg ethyl methanesulfonate, a known mutagen, once each day for 5 consecutive days. The mice were weighed just prior to the first day of exposure and at weekly intervals until sacrifice. During the fifth post-exposure week the animals were killed and examined for gross lesions of the reproductive tract and suspensions of the epididymal sperm were prepared for morphological evaluations. The appearance and behavior of the mice were unremarkable throughout the experiment and there were no deaths. No evidence of lesions in any organ was noted at sacrifice. Mean body weights of male mice exposed to n-hexane were not significantly different from those for the 0-ppM animals at any time during the study. Analyses of the sperm morphology data obtained 5 weeks post-exposure (the only time point examined) indicated that exposure of male mice to relatively high concentrations of n-hexane vapor for 5 days produced no significant effects on the morphology of sperm relative to that of the 0-ppM control group. 24 refs., 2 figs., 7 tabs.

  3. Gestational N-hexane inhalation alters the expression of genes related to ovarian hormone production and DNA methylation states in adult female F1 rat offspring.

    PubMed

    Li, Hong; Zhang, Chenyun; Ni, Feng; Guo, Suhua; Wang, Wenxiang; Liu, Jing; Lu, Xiaoli; Huang, Huiling; Zhang, Wenchang

    2015-12-15

    Research has revealed that n-hexane can disrupt adult female endocrine functions; however, few reports have focused on endocrine changes in adult F1 females after maternal exposure during gestation. In this study, female Wistar rats inhaled 100, 500, 2500, or 12,500ppm n-hexane for 4h daily during their initial 20 gestational days. The F1 female offspring exhibited abnormal oestrus cycles. Compared with the controls, the in vitro-cultured ovarian granulosa cells of the 12,500ppm group showed significantly reduced in vitro progesterone and oestradiol secretion. Elevated progesterone secretion was observed in the 500ppm group, and decreased and significantly upregulated mRNA expression of the Star, Cyp11a1, Cyp17a1, and Hsd3b genes was observed in the 12,500ppm and 500ppm groups, respectively. The protein expression levels were consistent with the mRNA expression levels. Methylation screening of the promoter regions of these genes was performed using MeDIP-chip and confirmed by methylation-sensitive high-resolution melting (MS-HRM), and the observed methylation state changes of the promoter regions were correlated with the gene expression levels. The results suggest that the hormone levels in the female offspring after gestational n-hexane inhalation correspond to the expression levels and DNA methylation states of the hormone production genes. PMID:26410608

  4. A detailed chemical kinetic reaction mechanism for the oxidation of iso-octane and n-heptane over an extended temperature range and its application to analysis of engine knock

    SciTech Connect

    Westbrook, C.K.; Warnatz, J.; Pitz, W.J.

    1988-01-11

    A detailed chemical kinetic reaction is developed to describe the oxidation of n-heptane, iso-octane, and their mixtures over a wide range of operating conditions. In addition to a high temperature submechanism, reaction paths are included to describe the lower temperature regimes in which the rate and intermediate products of oxidation are controlled by addition of molecular oxygen to alkyl and isomerized alkylperoxy radicals, internal H atom abstractions, and reactions involving O-heterocyclic species. The mechanism is then used to study the influence of fuel composition on knocking in internal combustion engines. Autoignition of mixtures of iso-octane and n-heptane is examined. The computations reproduce the variations of autoignition delay time with octane number and these variations are interpreted in terms of detailed differences in the structure of the two primary reference fuels. Sensitivity analyses of the computations are also presented. 30 refs., 2 figs.

  5. Determination of methylmercury in fish using focused microwave digestion following by Cu2+ addition, sodium tetrapropylborate derivatization, n-heptane extraction, and gas chromatography-mass spectrometry.

    PubMed

    Chen, Syr-Song; Chou, Shin-Shou; Hwang, Deng-Fwu

    2004-01-23

    The analytical procedure for analysis of methylmercury in fish was developed. It involves microwave-assisted digestion with alkaline solution (tetramethylammonium hydroxide), addition of Cu2+, aqueous-phase derivatization of methylmercury with sodium tetrapropylborate, and subsequent extraction with n-heptane. The methylmercury derivative was desorbed in the splitless injection port of a gas chromatograph and subsequently analyzed by electron impact mass spectrometry. Optimum conditions allowed sample throughout to be controlled by the instrumental analysis time (near 7 min per sample) but not by the sample preparation step. At the power of 15-30, 45, and 60-75 W, sample preparation time is only 3.5, 2.5, and 1.5 min, respectively. The proposed method was finally validated by the analysis of three biological certified reference materials, BCR CRM 464 tuna fish, NRC DORM-2 dogfish muscle, and NRC DOLT-2 dogfish liver. The detection limit of the overall procedure was found to be 40 ng/g of biological tissue for methylmercury. The recovery of methylmercury was 91.2-95.3% for tuna, 89.3-94.7% for marlin, and 91.7-94.8% for shark, respectively. The detected and certified values of methylmercury of three biological certified reference materials were as follows: 5.34 +/- 0.30 microg/g (mean +/- S.D.) and 5.50 +/- 0.17 microg/g for CRM 464 tuna fish, 4.34 +/- 0.24 and 4.47 +/- 0.32 microg/g for NRC DORM-2 dogfish muscle, and 0.652 +/- 0.053 and 0.693 +/- 0.055 microg/g for NRC DOLT-2 dogfish liver, respectively. It indicated that the method was well available to quantify the methylmercury in fish. PMID:14753723

  6. Cytotoxic agents for KB and SiHa cells from n-hexane fraction of Cissampelos pareira and its chemical composition.

    PubMed

    Bala, Manju; Pratap, Kunal; Verma, Praveen Kumar; Padwad, Yogendra; Singh, Bikram

    2015-01-01

    Eleven constituents were characterised by gas chromatography-mass spectrometry analysis, and five molecules were isolated using column chromatography. The in vitro study of the extract and isolated molecules against KB and SiHa cell lines revealed oleanolic acid (1) and oleic acid (2) as potent cytotoxic molecules with potential anticancer activity. The IC50 values of n-hexane extract (CPHF), oleanolic acid (1) and oleic acid (2) were >300, 56.08 and 70.7 ?g/mL (?M), respectively, against KB cell lines and >300, 47.24 and 80.2 ?g/mL (?M), respectively, against SiHa cell lines. PMID:25430075

  7. Steam reforming of n-hexane on pellet and monolithic catalyst beds. A comparative study on improvements due to heat transfer

    NASA Technical Reports Server (NTRS)

    1981-01-01

    Monolithic catalysts with higher available active surface areas and better thermal conductivity than conventional pellets beds, making possible the steam reforming of fuels heavier than naphtha, were examined. Performance comparisons were made between conventional pellet beds and honeycomb monolith catalysts using n-hexane as the fuel. Metal-supported monoliths were examined. These offer higher structural stability and higher thermal conductivity than ceramic supports. Data from two metal monoliths of different nickel catalyst loadings were compared to pellets under the same operating conditions. Improved heat transfer and better conversion efficiencies were obtained with the monolith having higher catalyst loading. Surface-gas interaction was observed throughout the length of the monoliths.

  8. Solid-liquid work of adhesion of coarse-grained models of n-hexane on graphene layers derived from the conditional reversible work method.

    PubMed

    Ardham, Vikram Reddy; Deichmann, Gregor; van der Vegt, Nico F A; Leroy, Frédéric

    2015-12-28

    We address the question of how reducing the number of degrees of freedom modifies the interfacial thermodynamic properties of heterogeneous solid-liquid systems. We consider the example of n-hexane interacting with multi-layer graphene which we model both with fully atomistic and coarse-grained (CG) models. The CG models are obtained by means of the conditional reversible work (CRW) method. The interfacial thermodynamics of these models is characterized by the solid-liquid work of adhesion WSL calculated by means of the dry-surface methodology through molecular dynamics simulations. We find that the CRW potentials lead to values of WSL that are larger than the atomistic ones. Clear understanding of the relationship between the structure of n-hexane in the vicinity of the surface and WSL is elucidated through a detailed study of the energy and entropy components of WSL. We highlight the crucial role played by the solid-liquid energy fluctuations. Our approach suggests that CG potentials should be designed in such a way that they preserve the range of solid-liquid interaction energies, but also their fluctuations in order to preserve the reference atomistic value of WSL. Our study thus opens perspectives into deriving CG interaction potentials that preserve the thermodynamics of solid-liquid contacts and will find application in studies that intend to address materials driven by interfaces. PMID:26723620

  9. Solid-liquid work of adhesion of coarse-grained models of n-hexane on graphene layers derived from the conditional reversible work method

    NASA Astrophysics Data System (ADS)

    Ardham, Vikram Reddy; Deichmann, Gregor; van der Vegt, Nico F. A.; Leroy, Frédéric

    2015-12-01

    We address the question of how reducing the number of degrees of freedom modifies the interfacial thermodynamic properties of heterogeneous solid-liquid systems. We consider the example of n-hexane interacting with multi-layer graphene which we model both with fully atomistic and coarse-grained (CG) models. The CG models are obtained by means of the conditional reversible work (CRW) method. The interfacial thermodynamics of these models is characterized by the solid-liquid work of adhesion WSL calculated by means of the dry-surface methodology through molecular dynamics simulations. We find that the CRW potentials lead to values of WSL that are larger than the atomistic ones. Clear understanding of the relationship between the structure of n-hexane in the vicinity of the surface and WSL is elucidated through a detailed study of the energy and entropy components of WSL. We highlight the crucial role played by the solid-liquid energy fluctuations. Our approach suggests that CG potentials should be designed in such a way that they preserve the range of solid-liquid interaction energies, but also their fluctuations in order to preserve the reference atomistic value of WSL. Our study thus opens perspectives into deriving CG interaction potentials that preserve the thermodynamics of solid-liquid contacts and will find application in studies that intend to address materials driven by interfaces.

  10. Effect of pressure on the hydrogen-bond formation between phenol as a proton donor and three ethers in N-hexane

    NASA Astrophysics Data System (ADS)

    Sawamura, S.; Tsuchiya, M.; Taniguchi, Y.; Suzuki, K.

    1986-05-01

    The effect of pressure on the hydrogen (H)-bond formation between phenol as a proton donor and three simple aliphatic ethers as proton acceptors in n-hexane was studied by means of UV absorption spectroscopy up to 640 MPa at 25°C. The reaction volumes for H-bond formation were -6.1 cm 3 mol -1 for diethyl-, -6.4 cm 3 mol -1 for di- n-propyl-, and -5.1 cm 3 mol -1 for di- n-butyl ether, respectively. They show that the reaction volume for H-bond formation between phenol and aliphatic ether is about -6 cm 3 mol -1 without depending on the length of the substituents of a proton donor.

  11. In vitro effects of straight-chain alkanes (n-hexane through n-dodecane) on rat liver and lung cytochrome P-450

    SciTech Connect

    Rabovsky, J.; Judy, D.J.; Pailes, W.H.

    1986-01-01

    To evaluate the effect of straight-chain alkanes on normal detoxication reactions a study was made of the in vitro effect of the homologous series n-hexane through n-dodecane on two cytochrome P-450 (EC 1.14 14.1) enzyme activities. Benzo(a)pyrene hydroxylase (BaPOHase) and 7-ethyoxycoumarin deethylase activities were measured in liver and lung microsomes of control and ..beta..-naphthoflavone-treated rats. In the presence of 2 mM n-hexane through n-dodecane, liver BaPOHase activity decreased from 67% of control with n-dodecane to 21% of control with octane. Lung benzo(a)pyrene hydroxylase was insensitive to all tested alkanes at 2 mM. In the presence of 2 mM alkanes, liver 7-ethoxycoumarin deethylase activity decreased from 73% of control with n-octane to 28% with n-octane. Lung 7-ethoxycoumarin deethylase was also sensitive to the alkane series. In the presence of 2 mM alkane the greatest effect was obtained with n-octane and represented a 56% loss in activity. Alkane concentration-dependent measurements showed 0.02-0.20 mM as the sensitive region of the curve for n-octane with maximal loss of activity achieved at 0.20 mM. Liver ethyoxycoumarin deethylase activity from ..beta..-naphthoflavone-treated rats was less sensitive towards the reactive alkane, n-octane, than the activity from control rats: Double-reciprocal-plot analysis revealed the maximal velocity (V/sub max/) was decreased in the presence of 0.2 mM n-octane. Hence this hydrocarbon did not exert its effect solely as an alternate substrate.

  12. N,N'-(Hexane-1,6-diyl)bis(4-methyl-N-(oxiran-2-ylmethyl)benzenesulfonamide): Synthesis via cyclodextrin mediated N-alkylation in aqueous solution and further Prilezhaev epoxidation

    PubMed Central

    Fischer, Julian; Millan, Simon

    2013-01-01

    Summary N-alkylation of N,N'-(hexane-1,6-diyl)bis(4-methylbenzenesulfonamide) with allyl bromide and subsequent Prilezhaev reaction with m-chloroperbenzoic acid to give N,N'-(hexane-1,6-diyl)bis(4-methyl-N-(oxiran-2-ylmethyl)benzenesulfonamide) is described. This twofold alkylation was performed in aqueous solution, whereby ?-, and randomly methylated ?-cyclodextrin were used as adequate phase transfer catalysts and the cyclodextrin–guest complexes were characterized by 1H NMR and 2D NMR ROESY spectroscopy. Finally, the curing properties of the diepoxide with lysine-based ?-amino-?-caprolactam were analyzed by rheological measurements. PMID:24367447

  13. Experimental neurotoxicity and urinary metabolites of the C5-C7 aliphatic hydrocarbons used as glue solvents in shoe manufacture

    SciTech Connect

    Frontali, N.; Amantini, M.C.; Spagnolo, A.; Guarcini, A.M.; Saltari, M.C.; Brugnone, F.; Perbellini, L.

    1981-12-01

    Rats were intermittently exposed (9 to 10 h/d, 5 to 6 d/week) to controlled concentrations of single analytical grad solvents in ambient air. After periods ranging from 7 to 30 weeks the animals were perfused with glutaraldehyde and samples of nerves were processed for light microscopy of sections and of teased fibers. Animals treated with n-hexane at 5000 ppm (14 weeks) or 2500 ppm (30 weeks) developed the typical giant axonal degeneration already described in rats treated continuously with 400 to 600 ppm of the same solvent for 7 weeks or more. No such alterations were found in rats subjected to the following intermittent respiratory treatments: n-hexane 500 ppm (30 weeks) or 1500 ppm (14 weeks), cyclohexane 1500 or 2500 (30 weeks), n-pentane 3000 ppm (30 weeks), n-heptane 1500 ppm (30 weeks), 2-methylpentane 1500 ppm (14 weeks), and 3-methylpentane 1500 ppm (14 weeks). The following metabolites were found in the urine of rats according to treatment (in parenthesis): 2-methyl-2-pentanol (2-methylpentane); 3-methyl-2-pentanol and 3-methyl-3-pentanol (3-methylpentane), 2-hexanol, 3-hexanol, gamma-valerolactone, 2,5-dimethylfuran, and 2,5-hexanedione (n-hexane). 2-Hexanol was found to be the main urinary metabolite of n-hexane, while 2,5-hexanedione was present only in a lesser proportion. This feature of rat metabolism suggests that in this species 2,5-hexanedione reaches an effective level at its site of action during intermittent respiratory treatment with n-hexane with difficulty and explains the high concentrations necessary to cause polyneuropathy in rats subjected to this treatment.

  14. Dilution method study on the interfacial composition and structural parameters of water/C12-EOx-C12.2Br/n-hexanol/n-heptane microemulsions: effect of the oxyethylene groups in the spacer.

    PubMed

    Zheng, Ou; Zhao, Jian-Xi; Yan, Hua; Gao, Shao-Kang

    2007-06-01

    The interfacial composition and the structure of the water/C(12)-EO(x)-C(12).2Br/n-hexanol/n-heptane microemulsion have been investigated by the dilution method. The results showed that C(12)-EO(x)-C(12).2Br formed a stable water/oil microemulsion with the assistance of n-hexanol. Owing to the relatively large size of the head group, more n-hexanol molecules are populated on the droplet surface than in the C(12)-2-C(12).2Br system. The radius of the water pool of the C(12)-EO(3)-C(12).2Br system is not as sensitive to W(0) as in the C(12)-2-C(12).2Br system. Another feature of the present system is that its droplet size is considerably smaller than that of the C(12)-2-C(12).2Br system, and also those of the CPC and CTAB systems at relative high water content. This provides a potential application for the synthesis of nanoparticles with small size. PMID:17303155

  15. Rate Constants for the Reactions of Hydroxyl Radical with Several Alkanes, Cycloalkanes, and Dimethyl Ether

    NASA Technical Reports Server (NTRS)

    DeMore, W.; Bayes, K.

    1998-01-01

    Relative rate experiements were used to measure rate constants and temperature denpendencies of the reactions of OH with propane, n-butane, n-pentane, n-hexane, cyclopropane, cyclobutane, cyclopentane, and dimethyl ether.

  16. Comparative effect of organosulfur compounds on catalysts for the n-heptane isomerization reaction at medium pressure: Mo{sub 2}C-oxygen-modified, MoO{sub 3}-carbon-modified, Pt/{gamma}-Al{sub 2}O{sub 3}, and Pt/{beta}-zeolite catalysts

    SciTech Connect

    York, A.P.E.; Pham-Huu, C.; Del Gallo, P.; Ledoux, M.J.; Blekkan, E.A.

    1996-03-01

    Molybdenum oxycarbide formed from oxidized Mo{sub 2}C or reduced MoO{sub 3} is an active and very selective catalyst for the isomerization of n-heptane compared to supported Pt. Deactivation experiments performed on the catalysts with different concentrations of organosulfur compounds show that molybdenum oxycarbide exhibits a very high resistance to deactivation, whereas with platinum-based catalysts deactivation occurs even at low sulfur concentration in the feed. Deactivation can be slowed by increasing the hydrogen partial pressure from 6 to 20 bar. In these conditions, the molybdenum oxycarbide shows no deactivation with sulfur concentrations up to 120 ppm of S. In addition, the deactivated molybdenum catalysts can be easily regenerated by mild oxidative treatment under flowing air at atmospheric pressure and 723 K for 2 h followed by a reactivation period under the hydrogen and hydrocarbon mixture.

  17. STRUCTURAL CHARACTERIZATION OF ASPHALTENES AND ETHYL ACETATE INSOLUBLE FRACTIONS OF PETROLEUM VACUUM RESIDUES

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Asphaltenes and insoluble fractions of vacuum residues (VRs) of two Indian crude oils (viz. Heera and Jodhpur) of different specific gravity were obtained by precipitation of VRs in n-hexane, n-heptane and ethyl acetate, and also by subsequent reprecipitation of n-heptane and ethyl acetate soluble f...

  18. Direct observation of metal nanoparticles as heterogeneous nuclei for the condensation of supersaturated organic vapors: nucleation of size-selected aluminum nanoparticles in acetonitrile and n-hexane vapors.

    PubMed

    Abdelsayed, Victor; El-Shall, M Samy

    2014-08-01

    This work reports the direct observation and separation of size-selected aluminum nanoparticles acting as heterogeneous nuclei for the condensation of supersaturated vapors of both polar and nonpolar molecules. In the experiment, we study the condensation of supersaturated acetonitrile and n-hexane vapors on charged and neutral Al nanoparticles by activation of the metal nanoparticles to act as heterogeneous nuclei for the condensation of the organic vapor. Aluminum seed nanoparticles with diameters of 1 and 2 nm are capable of acting as heterogeneous nuclei for the condensation of supersaturated acetonitrile and hexane vapors. The comparison between the Kelvin and Fletcher diameters indicates that for the heterogeneous nucleation of both acetonitrile and hexane vapors, particles are activated at significantly smaller sizes than predicted by the Kelvin equation. The activation of the Al nanoparticles occurs at nearly 40% and 65% of the onset of homogeneous nucleation of acetonitrile and hexane supersaturated vapors, respectively. The lower activation of the charged Al nanoparticles in acetonitrile vapor is due to the charge-dipole interaction which results in rapid condensation of the highly polar acetonitrile molecules on the charged Al nanoparticles. The charge-dipole interaction decreases with increasing the size of the Al nanoparticles and therefore at low supersaturations, most of the heterogeneous nucleation events are occurring on neutral nanoparticles. No sign effect has been observed for the condensation of the organic vapors on the positively and negatively charged Al nanoparticles. The present approach of generating metal nanoparticles by pulsed laser vaporization within a supersaturated organic vapor allows for efficient separation between nucleation and growth of the metal nanoparticles and, consequently controls the average particle size, particle density, and particle size distribution within the liquid droplets of the condensing vapor. Strong correlation is found between the seed nanoparticle's size and the degree of the supersaturation of the condensing vapor. This result and the agreement among the calculated Kelvin diameters and the size of the nucleating Al nanoparticles determined by transmission electron microscopy provide strong proof for the development of a new approach for the separation and characterization of heterogeneous nuclei formed in organic vapors. These processes can take place in the atmosphere by a combination of several organic species including polar compounds which could be very efficient in activating charged nanoparticles and cluster ions of atmospheric relevance. PMID:25106603

  19. Rate constants for OH with selected large alkanes : shock-tube measurements and an improved group scheme.

    SciTech Connect

    Sivaramakrishnan, R.; Michael, J. V.; Chemical Sciences and Engineering Division

    2009-04-30

    High-temperature rate constant experiments on OH with the five large (C{sub 5}-C{sub 8}) saturated hydrocarbons n-heptane, 2,2,3,3-tetramethylbutane (2,2,3,3-TMB), n-pentane, n-hexane, and 2,3-dimethylbutane (2,3-DMB) were performed with the reflected-shock-tube technique using multipass absorption spectrometric detection of OH radicals at 308 nm. Single-point determinations at {approx}1200 K on n-heptane, 2,2,3,3-TMB, n-hexane, and 2,3-DMB were previously reported by Cohen and co-workers; however, the present work substantially extends the database to both lower and higher temperature. The present experiments span a wide temperature range, 789-1308 K, and represent the first direct measurements of rate constants at T > 800 K for n-pentane. The present work utilized 48 optical passes corresponding to a total path length of {approx}4.2 m. As a result of this increased path length, the high OH concentration detection sensitivity permitted pseudo-first-order analyses for unambiguously measuring rate constants. The experimental results can be expressed in Arrhenius form in units of cm{sup 3} molecule{sup -1} s{sup -1} as follows: K{sub OH+n-heptane} = (2.48 {+-} 0.17) x 10{sup -10} exp[(-1927 {+-} 69 K)/T] (838-1287 K); k{sub OH+2,2,3,3-TMB} = (8.26 {+-} 0.89) x 10{sup -11} exp[(-1337 {+-} 94 K)/T] (789-1061 K); K{sub OH+n-pentane} = (1.60 {+-} 0.25) x 10{sup -10} exp[(-1903 {+-} 146 K)/T] (823-1308 K); K{sub OH+n-hexane} = (2.79 {+-} 0.39) x 10{sup -10} exp[(-2301 {+-} 134 K)/T] (798-1299 K); and k{sub OH+2,3-DMB} = (1.27 {+-} 0.16) x 10{sup -10} exp[(-1617 {+-} 118 K)/T] (843-1292 K). The available experimental data, along with lower-T determinations, were used to obtain evaluations of the experimental rate constants over the temperature range from {approx}230 to 1300 K for most of the title reactions. These extended-temperature-range evaluations, given as three-parameter fits, are as follows: k{sub OH+n-heptane} = 2.059 x 10{sup -5}T{sup 1.401} exp(33 K/T) cm{sup 3} molecule{sup -1} s{sup -1} (241-1287 K); k{sub OH+2,2,3,3-TMB} = 6.835 x 10{sup -17}T{sup 1.886} exp(-365 K/T) cm{sup 3} molecule{sup -1} s{sup -1} (290-1180 K); k{sub OH+n-pentane} = 2.495 x 10{sup -16}T{sup 1.649} exp(80 K/T) cm{sup 3} molecule{sup -1} s{sup -1} (224-1308 K); k{sub OH+n-hexane} = 3.959 x 10{sup -18}T{sup 2.218} exp(443 K/T) cm{sup 3} molecule{sup -1} s{sup -1} (292-1299 K); and k{sub OH+2,3-DMB} = 2.287 x 10{sup -17}T{sup 1.958} exp(365 K/T) cm{sup 3} molecule{sup -1} s{sup -1} (220-1292 K). The experimental data and the evaluations obtained for these five larger alkanes in the present work were used along with prior data/evaluations obtained in this laboratory for H abstractions by OH from a series of smaller alkanes (C{sub 3}?C{sub 5}) to devise rate rules for abstractions from various types of primary, secondary, and tertiary H atoms. Specifically, the current scheme was applied with good success to H abstractions by OH from a series of n-alkanes (n-octane through n-hexadecane). The total rate constants using this group scheme for reactions of OH with selected large alkanes are given as three-parameter fits in this article. The rate constants for the various abstraction channels in any large n-alkane can also be obtained using the groups listed in this article. The present group scheme serves to reduce the uncertainties in rate constants for OH + alkane reactions.

  20. Electron mobility, free ion yields, and electron thermalization distances in n-alkane liquids: Effect of chain length

    NASA Astrophysics Data System (ADS)

    Gee, Norman; Senanayake, P. Chandani; Freeman, Gordon R.

    1988-09-01

    The electron mobility ?o was measured as a function of temperature in liquid n-hexane, n-heptane, n-octane, n-nonane, and n-undecane, and at 295 K in n-pentane. Combination of these with earlier measurements of ours showed that ?0 at 295 K decreased monotonically with increasing carbon chain length in n-alkane liquids from ethane to n-tetradecane. There was no significant difference between odd and even carbon number compounds. The results were in accord with two-state interpretations of electron transport. Free ion yields were measured in liquid n-Cx H2x+2 (4?x?14, except 13) and electron thermalization ranges bGP were estimated using the extended Onsager model. The zero field free ion yield G0fi at 295 K decreased with increasing chain length. The density-normalized thermalization range of electrons was bGPd=(41±1)×10-7 kg/m2 in all n-alkanes from C4 to C14 under the conditions of this study.

  1. Determination of thermodynamic properties of poly (cyclohexyl methacrylate) by inverse gas chromatography.

    PubMed

    Kaya, Ismet; Pala, Cigdem Yigit

    2014-07-01

    In this work, some thermodynamic properties of poly (cyclohexyl methacrylate) were studied by inverse gas chromatography (IGC). For this purpose, the polymeric substance was coated on Chromosorb W and which was filled into a glass column. The retention times (t(r)) of the probes were determined from the interactions of poly (cyclohexyl methacrylate) with n-pentane, n-hexane, n-heptane, n-octane, n-decane, methanol, ethanol, 2-propanol, butanol, acetone, ethyl methyl ketone, benzene, toluene and o-xylene by IGC technique. Then, the specific volume (Vg(0)) was determined for each probe molecule. By using (1/T; lnVg(0)) graphics, the glass transition temperature of poly (cyclohexyl methacrylate) was found to be 373 K. The adsorption heat under the glass transition temperature (deltaH(a)), and partial molar heat of sorption above the glass transition (deltaH1(S)), partial molar free energy of sorption (deltaG1(S)) and partial molar entropy of sorption (deltaS1(S)) belonging to sorption for every probe were calculated. The partial molar heat of mixing at infinite dilution (deltaH1(infinity)), partial molar free energy of mixing at infinite dilution (deltaG1(infinity)), Flory-Huggins interaction parameter (chi12(infinity)) and weight fraction activity coefficient (a1/w1)(infinity) values of polymer-solute systems were calculated at different column temperatures. The solubility parameters (delta2) of the polymer were obtained by IGC technique. PMID:25255568

  2. Non-methane hydrocarbons in industrial locations of Bombay

    NASA Astrophysics Data System (ADS)

    Mohan Rao, A. M.; Pandit, G. G.; Sain, P.; Sharma, S.; Krishnamoorthy, T. M.; Nambi, K. S. V.

    Concentrations of non-methane hydrocarbons in atmospheric air are measured in areas close to five industrial locations in the city of Bombay during the period March 1993 to May 1994. Seventeen hydrocarbons, viz., ethane, ethylene, acetylene, propane, propylene, i-butane, n-butane, i-pentane, n-pentane, n-hexane, benzene, n-heptane, toluene, ethylbenzene, p-xylene, o-xylene, n-decane and identified in 260 urban air samples using a cryogenic preconcentration system and a Gaschromatograph with a flame-ionization detector. Analysis is done on packed columns: N-octane Poracil C column for the C 2?C 5, OV-101 column for the C 6 and above hydrocarbons. A significant fraction of the C 6?C 10 hydrocarbons remains unidentified. About 44% of the samples collected in the Thane region of Bombay (with large number of chemical industries) and 50.8% of the samples collected in the Mahul region of Bombay (adjacent to two oil refining units) showed concentrations above 240 ppbv, which is the recognized air quality standard for zones with chemical industries by the Maharashtra Pollution Control Board. The concentrations of C 6?C 10 hydrocarbons were more than that for C 2?C 5 at the two industrial sites located at Thane region of Bombay, while the C 2?C 5 hydrocarbons were more at the Refineries area near Mahul, Bombay. Benzene concentrations are observed to be above 5.0 ppbv at four of the five chosen sites and its concentration was more than that of toluene. These studies indicate significantly higher ratios for some of the individual hydrocarbon to acetylene in air than corresponding autoexhaust values.

  3. [Surface characterization of urushiol-titanium chelate polymers by inverse gas chromatography].

    PubMed

    Xu, Yanlian; Lin, Jinhuo; Xia, Jianrong; Hu, Binghuan

    2011-03-01

    Urushiol-titanium chelate polymer (UTP), the reaction product of urushiol with titanium compound, is a special eco-friendly polymer with excellent performances, such as strong acids-resistance, strong alkalis-resistance, salt solution-resistance and several organic solvent-resistance. Inverse gas chromatography (IGC) was used to measure the dispersive component of surface free energy (gamma(s)d) and the Lewis acid-base parameters of UTP in this work. The gamma(s)d and the acid/base characters of UTP' surfaces were estimated by the retention time with different non-polar and polar probes at infinite dilution region. n-Pentane (C5), n-hexane (C6), n-heptane (C7), n-octane (C8) and n-nonane (C9) were chosen as the non-polar probes to characterize the gamma(s)d. Trichloromethane (CHCl3), tetrahydrofuran (THF) and acetone were chosen as polar probes to detect the Lewis acid-base parameters. The specific free energy (deltaG(a)AB) and the enthalpy (deltaH(a)AB) of adsorption corresponding to acid-base surface interactions were determined. By correlating deltaH(a)AB with the donor and acceptor numbers of the probes, the acidic (K(a)) and the basic (K(b)) parameters of the samples were calculated. The results showed that the dispersive components of the free energy of UTP were 37.68, 33.53, 35.92, 24.01 and 31.32 mJ/m2 at 70, 80, 90, 100 and 110 degrees C, respectively. The Lewis acidic number K(a) of UTP was 0.185 3, and the Lewis basic number K(b) was 0.966 2. The results were of great importance to the study of the surface properties and the applications for urushiol-metal chelate polymers. PMID:21657056

  4. Reversible cerebral and brain stem dysfunction in n: Hexane neuropathy

    PubMed Central

    Puri, Vinod; Gupta, Abhijit Das; Chaudhry, Neera; Saran, Ravindra Kumar

    2015-01-01

    A 18-year-old male, screen printer by profession developed sensory motor polyneuropathy, change in his behavior, bilateral 6th and 7th cranial nerve palsies, down beat nystagmus and cerebellar dysarthria. He had bilaterally prolonged P100 latency; left: 137 ms; right: 144 ms. P 37 was not recordable on either side while N 20 was normal. The inter latency difference between Ipsilateral R2 and Contralateral R2 was 6.15 ms, on the left side and normal on the right side. In the follow-up, there was normalization of the blink reflex study, improvement in P100 latency [left: 114 ms; right: 120 ms.] but worsening of peripheral nerve conductions. The sequential clinical recovery was of the behavioral dysfunction, down beat nystagmus, 6th nerve, 7th nerve involvement and ataxia, in that order. Sural nerve biopsy showed loss of large diameter myelinated fibers. PMID:26713026

  5. Reversible cerebral and brain stem dysfunction in n: Hexane neuropathy.

    PubMed

    Puri, Vinod; Gupta, Abhijit Das; Chaudhry, Neera; Saran, Ravindra Kumar

    2015-01-01

    A 18-year-old male, screen printer by profession developed sensory motor polyneuropathy, change in his behavior, bilateral 6(th) and 7(th) cranial nerve palsies, down beat nystagmus and cerebellar dysarthria. He had bilaterally prolonged P100 latency; left: 137 ms; right: 144 ms. P 37 was not recordable on either side while N 20 was normal. The inter latency difference between Ipsilateral R2 and Contralateral R2 was 6.15 ms, on the left side and normal on the right side. In the follow-up, there was normalization of the blink reflex study, improvement in P100 latency [left: 114 ms; right: 120 ms.] but worsening of peripheral nerve conductions. The sequential clinical recovery was of the behavioral dysfunction, down beat nystagmus, 6(th) nerve, 7(th) nerve involvement and ataxia, in that order. Sural nerve biopsy showed loss of large diameter myelinated fibers. PMID:26713026

  6. Process Engineering Thermodynamics 424304 E (4 sp)

    E-print Network

    Zevenhoven, Ron

    . A mixture of n-hexane (n-C6) and n-octane (n-C8) is fed into a distillation column at atmospheric pressure. Estimate the number of theoretical stages for the column. (2+4+1½ p.) F mol/min xF = ? D = 500 mol/min xF = 0.5 mol/mol) of n-pentane (n-C5) and n-octane (n-C8) is separated at atmospheric pressure

  7. Numerical Study of NOx Emissions from n-Heptane and 1-Heptene Counterflow Flames

    E-print Network

    Aggarwal, Suresh K.

    produced via the esterification process by transforming vegetable oil or animal fat through reactions of vegetable- oil-based biodiesel fuels include methyl esters made from canola, coconut, palm, peanut, soy, and rapeseed oils. Their chemical composition and properties vary over a wide range depending upon the source

  8. Effects of oxygenate concentration on species mole fractions in premixed n-heptane flames

    E-print Network

    Senkan, Selim M.

    for the determination of gasoline octane number which rates fuel's tendency to knock in an engine under standardized in these emissions is the improvement in motor vehicle fuel properties. Fuel oxygenates were first used as an octane

  9. Corona discharge of Titan's troposphere

    NASA Astrophysics Data System (ADS)

    Navarro-González, Rafael; Ramírez, Sandra I.

    1997-05-01

    The atmosphere of Titan is constantly bombarded by galactic cosmic rays and Saturnian magnetospheric electrons causing the formation of free electrons and primary ions, which are then stabilized by ion cluster formation and charging of aerosols. These charged particles accumulate in drops in cloud regions of the troposphere. Their abundance can substantially increase by friction, fragmentation or collisions during convective activity. Charge separation occurs with help of convection and gravitational settling leading to development of electric fields within the cloud and between the cloud and the ground. Neutralization of these charge particles leads to corona discharges which are characterized by low current densities. These electric discharges could induce a number of chemical reactions in the troposphere and hence it is of interest to explore such effects. We have therefore, experimentally studied the corona discharge of a simulated Titan's atmosphere (10% methane and 2% argon in nitrogen) at 500 Torr and 298 K by GC-FTIR-MS techniques. The main products have been identified as hydrocarbons (ethane, ethyne, ethene, propane, propene + propyne, cyclopropane, butane, 2-methylpropane, 2-methylpropene, n-butene, 2-butene, 2,2-dimethylpropane, 2-methylbutane, 2-methylbutene, n-pentane, 2,2-dimethylbutane, 2-methylpentane, 3-methylpentane, n-hexane, 2,2-dimethylhexane, 2,2-dimethylpentane, 2,2,3-trimethylbutane, 2,3-dimethylpentane and n-heptane), nitriles (hydrogen cyanide, cyanogen, ethanenitrile, propanenitrile, 2-methylpropanenitrile and butanenitrile) and an uncharacterized film deposit. We present their trends of formation as a function of discharge time in an ample interval and have derived their initial yields of formation. These results clearly demonstrate that a complex organic chemistry can be initiated by corona processes in the lower atmosphere. Although photochemistry and charged particle chemistry occurring in the stratosphere can account for many of the observed hydrocarbon species in Titan, the predicted abundance of ethene is to low by a factor of 10 to 40. While some ethene will be produced by charged-particle chemistry, its production by corona processes and subsequent diffusion into the stratosphere appears to be an adequate source. Because little UV penetrates to the lower atmosphere to destroy the molecules formed there, the corona-produced species may be long-lived and contribute significantly to the composition of the lower atmosphere and surface.

  10. A study of PVT relations for carbon dioxide, n-pentane, and n-octane mixtures using a recombination apparatus 

    E-print Network

    Wirawan, Januar Fitri Santo

    1993-01-01

    Carbon dioxide flooding is considered to have a multi- contact miscibility displacement mechanism. It changes the reservoir fluid in a complex manner. This type of Enhanced Oil Recovery (EOR) technique is very economically viable, readily...

  11. Estimated MP2 and CCSD(T) interaction energies of n-alkane dimers at the basis set limit: Comparison of the methods of Helgaker et al. and Feller

    NASA Astrophysics Data System (ADS)

    Tsuzuki, Seiji; Honda, Kazumasa; Uchimaru, Tadafumi; Mikami, Masuhiro

    2006-03-01

    The MP2 (the second-order Møller-Plesset calculation) and CCSD(T) (coupled cluster calculation with single and double substitutions with noniterative triple excitations) interaction energies of all-trans n-alkane dimers were calculated using Dunning's [J. Chem. Phys. 90, 1007 (1989)] correlation consistent basis sets. The estimated MP2 interaction energies of methane, ethane, and propane dimers at the basis set limit [EMP2(limit)] by the method of Helgaker et al. [J. Chem. Phys. 106, 9639 (1997)] from the MP2/aug-cc-pVXZ (X =D and T) level interaction energies are very close to those estimated from the MP2/aug-cc-pVXZ (X =T and Q) level interaction energies. The estimated EMP2(limit) values of n-butane to n-heptane dimers from the MP2/cc-pVXZ (X =D and T) level interaction energies are very close to those from the MP2/aug-cc-pVXZ (X =D and T) ones. The EMP2(limit) values estimated by Feller's [J. Chem. Phys. 96, 6104 (1992)] method from the MP2/cc-pVXZ (X =D, T, and Q) level interaction energies are close to those estimated by the method of Helgaker et al. from the MP2/cc-pVXZ (X =T and Q) ones. The estimated EMP2(limit) values by the method of Helgaker et al. using the aug-cc-pVXZ (X =D and T) are close to these values. The estimated EMP2(limit) of the methane, ethane, propane, n-butane, n-pentane, n-hexane, n-heptane, n-octane, n-nonane, and n-decane dimers by the method of Helgaker et al. are -0.48, -1.35, -2.08, -2.97, -3.92, -4.91, -5.96, -6.68, -7.75, and -8.75kcal /mol, respectively. Effects of electron correlation beyond MP2 are not large. The estimated CCSD(T) interaction energies of the methane, ethane, propane, and n-butane dimers at the basis set limit by the method of Helgaker et al. (-0.41, -1.22, -1.87, and -2.74kcal/mol, respectively) from the CCSD(T )/cc-pVXZ (X =D and T) level interaction energies are close to the EMP2(limit) obtained using the same basis sets. The estimated EMP2(limit) values of the ten dimers were fitted to the form m0+m1X (X is 1 for methane, 2 for ethane, etc.). The obtained m0 and m1 (0.595 and -0.926kcal /mol) show that the interactions between long n-alkane chains are significant. Analysis of basis set effects shows that cc-pVXZ (X =T, Q, or 5), aug-cc-pVXZ (X =D, T, Q, or 5) basis set, or 6-311G** basis set augmented with diffuse polarization function is necessary for quantitative evaluation of the interaction energies between n-alkane chains.

  12. Adsorption of n-alkane vapours at the water surface.

    PubMed

    Biscay, Frédéric; Ghoufi, Aziz; Malfreyt, Patrice

    2011-06-21

    Monte Carlo simulations are reported here to predict the surface tension of the liquid-vapour interface of water upon adsorption of alkane vapours (methane to hexane). A decrease of the surface tension has been established from n-pentane. A correlation has been evidenced between the decrease of the surface tension and the absence of specific arrangement at the water surface for n-pentane and n-hexane. The thermodynamic stability of the adsorption layer and the absence of film for longer alkanes have been checked through the calculation of a potential of mean force. This complements the work recently published [Ghoufi et al., Phys. Chem. Chem. Phys., 2010, 12, 5203] concerning the adsorption of methane at the water surface. The decrease of the surface tension has been interpreted in terms of the degree of hydrogen bonding of water molecules at the liquid-vapour interface upon adsorption. PMID:21584320

  13. Proceedings of the Combustion Institute, Volume 28, 2000/pp. 20292037 EXTINCTION AND AUTOIGNITION OF n-HEPTANE

    E-print Network

    Pitsch, Heinz

    for octane rating in internal combustion engines. It has a cetane number of ap- proximately 56, which reactors, and concentration histories of a number of species in plug-flow and jet-stirred reactors

  14. Effect of Unsaturated Bond on NOx and PAH Formation in nHeptane and 1Heptene Triple Flames

    E-print Network

    Aggarwal, Suresh K.

    . An important characteristic of biodiesels, produced from the transesterification of vegetable oils and animal, and pollutant emissions. McCormick et al.3 performed engine tests using several biodiesel fuels from different

  15. An analytical system for the measurement of stable hydrogen isotopes in ambient volatile organic compounds

    NASA Astrophysics Data System (ADS)

    Meisehen, T.; Bühler, F.; Koppmann, R.; Krebsbach, M.

    2015-07-01

    Stable isotope measurements in atmospheric volatile organic compounds (VOC) are an excellent tool to analyse chemical and dynamical processes in the atmosphere. While up to now isotope studies of VOC in ambient air mainly focus on carbon isotopes, we herein present a new measurement system to investigate hydrogen isotope ratios in atmospheric VOC. This system consisting of a GC-P-IRMS (Gas Chromatography Pyrolysis Isotope Ratio Mass Spectrometer) and a preconcentration system was thoroughly characterised using a working standard. A precision of better than 9 ‰ (in ?D) is achieved for n-pentane, 2-methyl-1,3-butadiene (isoprene), n-heptane, 4-methyl-pentane-2-one (4-methyl-2-pentanone), methylbenzene (toluene), n-octane, ethylbenzene, m/p-xylene, and 1,2,4-trimethylbenzene. A comparison with independent measurements via elemental analysis shows an accuracy of better than 9 ‰ for n-pentane, n-heptane, 4-methyl-2-pentanone, toluene, and n-octane. Above a compound specific minimum peak area the obtained ?D values are constant within the standard deviations. In addition, a remarkable influence of the pyrolysis process on the isotope ratios is found and discussed. Reliable measurements are only possible if the ceramic tube used for the pyrolysis is sufficiently conditioned, i.e. the inner surface is covered with a carbon layer. It is essential to verify this conditioning regularly and to renew it if required. Furthermore, influences of a necessary H3+ correction and the pyrolysis temperature on the isotope ratios are discussed. Finally, the applicability to measure hydrogen isotope ratios in VOC at ambient levels is demonstrated with measurements of outside air on five different days in February and March 2015. The measured hydrogen isotope ratios range from -136 to -105 ‰ for n-pentane, from -86 to -63 ‰ for toluene, from -39 to -15 ‰ for ethylbenzene, from -99 to -68 ‰ for m/p-xylene, and from -45 to -34 ‰ for o-xylene.

  16. Total cross section of electron scattering by fluorocarbon molecules

    NASA Astrophysics Data System (ADS)

    Yamada, T.; Ushiroda, S.; Kondo, Y.

    2008-12-01

    A compact linear electron transmission apparatus was used for the measurement of the total electron scattering cross section at 4-500 eV. Total cross sections of chlorofluorocarbon (CCl2F2), hydrochlorofluorocarbon (CHClF2), perfluoropropane (C3F8), perfluoro-n-pentane (C5F12), perfluoro-n-hexane (C6F14) and perfluoro-n-octane (C8F18) were obtained experimentally and compared with the values obtained from a theoretical calculation and semi-empirical model calculation.

  17. Retama monosperma n-hexane extract induces cell cycle arrest and extrinsic pathway-dependent apoptosis in Jurkat cells

    PubMed Central

    2014-01-01

    Background Retama monosperma L. (Boiss.) or Genista monosperma L. (Lam.), locally named as “R’tam”, is an annual and spontaneous plant belonging to the Fabaceae family. In Morocco, Retama genus is located in desert regions and across the Middle Atlas and it has been widely used in traditional medicine in many countries. In this study, we show that Retama monosperma hexane extract presents significant anti-leukemic effects against human Jurkat cells. Methods Human Jurkat cells, together with other cell lines were screened with different concentrations of Retama monosperma hexane extract at different time intervals. Growth inhibition was determined using luminescent-based viability assays. Cell cycle arrest and apoptosis were measured by flow cytometry analysis. Combined caspase 3 and 7 activities were measured using luminometric caspase assays and immunoblots were performed to analyze expression of relevant pro- and anti-apoptotic proteins. GC-MS were used to determine the chemical constituents of the active extract. Results Retama monosperma hexane extract (Rm-HE) showed significant cytotoxicity against Jurkat cells, whereas it proved to be essentially ineffective against both normal mouse fibroblasts (NIH3T3) and normal lymphocytes (TK-6). Cytometric analysis indicated that Rm-HE promoted cell cycle arrest and apoptosis induction accompanied by DNA damage induction indicated by an increase in p-H2A.X levels. Rm-HE induced apoptosis was partially JNK-dependent and characterized by an increase in Fas-L levels together with activation of caspases 8, 3, 7 and 9, whereas neither the pro-apoptotic nor anti-apoptotic mitochondrial membrane proteins analyzed were significantly altered. Chemical identification analysis indicated that ?-linolenic acid, campesterol, stigmasterol and sitosterol were the major bioactive components within the extract. Conclusions Our data suggest that bioactive compounds present in Rm-HE show significant anti leukemic activity inducing cell cycle arrest and cell death that operates, at least partially, through the extrinsic apoptosis pathway. PMID:24460687

  18. Prediction of fluid phase equilibrium of ternary mixtures in the critical region and the modified Leung-Griffiths theory

    NASA Astrophysics Data System (ADS)

    Lynch, John J.; Rainwater, James C.; van Poolen, Lambert J.; Smith, Duane H.

    1992-02-01

    The modified Leung-Griffiths theory of vapor-liquid equilibrium (VLE) is generalized to the case of three components. The principle of 'corresponding states' is reconsidered along with certain functions of 'field variables' within the model. The mathematical form of the coexistence boundary in terms of the field variables remains practically unchanged and conforms to modern scaling theory. The new model essentially predicts ternary fluid mixture phase boundaries in the critical region from previous vapor-liquid equilibrium data correlations of the three binary fluid mixture limits. Predicted saturation isotherms of the ethane + n-butane + n-pentane and ethane + n-butane + n-heptane mixtures are compared with experimental ternary VLE data in the literature.

  19. Combustion of liquid fuels in a flowing combustion gas environment at high pressures

    NASA Technical Reports Server (NTRS)

    Canada, G. S.; Faeth, G. M.

    1975-01-01

    The combustion of fuel droplets in gases which simulate combustion chamber conditions was considered both experimentally and theoretically. The fuel droplets were simulated by porous spheres and allowed to gasify in combustion gases produced by a burner. Tests were conducted for pressures of 1-40 atm, temperatures of 600-1500 K, oxygen concentrations of 0-13% (molar) and approach Reynolds numbers of 40-680. The fuels considered in the tests included methanol, ethanol, propanol-1, n-pentane, n-heptane and n-decane. Measurements were made of both the rate of gasification of the droplet and the liquid surface temperature. Measurements were compared with theory, involving various models of gas phase transport properties with a multiplicative correction for the effect of forced convection.

  20. High pressure combustion of liquid fuels. [alcohol and n-paraffin fuels

    NASA Technical Reports Server (NTRS)

    Canada, G. S.

    1974-01-01

    Measurements were made of the burning rates and liquid surface temperatures for a number of alcohol and n-paraffin fuels under natural and forced convection conditions. Porous spheres ranging in size from 0.64-1.9 cm O.D. were emloyed to simulate the fuel droplets. The natural convection cold gas tests considered the combustion in air of methanol, ethanol, propanol-1, n-pentane, n-heptane, and n-decane droplets at pressures up to 78 atmospheres. The pressure levels of the natural convection tests were high enough so that near critical combustion was observed for methanol and ethanol vaporization rates and liquid surface temperature measurements were made of droplets burning in a simulated combustion chamber environment. Ambient oxygen molar concentrations included 13%, 9.5% and pure evaporation. Fuels used in the forced convection atmospheric tests included those listed above for the natural convection tests. The ambient gas temperature ranged from 600 to 1500 K and the Reynolds number varied from 30 to 300. The high pressure forced convection tests employed ethanol and n-heptane as fuels over a pressure range of one to 40 atmospheres. The ambient gas temperature was 1145 K for the two combustion cases and 1255 K for the evaporation case.

  1. LIQUID-LIQUID EQUILIBRIA FOR THREE- AND FOUR-COMPONENT SYSTEMS COMPRISED OF WATER + ETHANOL + TOLUENE + N-HEPTANE AT 293 K (R821114)

    EPA Science Inventory

    The perspectives, information and conclusions conveyed in research project abstracts, progress reports, final reports, journal abstracts and journal publications convey the viewpoints of the principal investigator and may not represent the views and policies of ORD and EPA. Concl...

  2. Effects of light and copper ions on volatile aldehydes of milk and milk fractions

    SciTech Connect

    Jeno, W.; Bassette, R.; Crang, R.E.

    1988-09-01

    Raw, laboratory-pasteurized and plant-pasteurized homogenized milks were exposed to copper ions (5 ppm), to sunlight or fluorescent light and the effects determined on the composition of volatile aldehydes. The greatest change due to copper treatment was an increase in n-hexanal; acetaldehyde showed the least response in each of the sources of milk. The responses were similar from all three sources of milk with laboratory-pasteurized milk samples showing the greatest responses for each aldehyde analyzed. Similar milk samples exposed to sunlight also showed an increase in volatile aldehydes from all milk sources but with the greatest response being acetaldehyde and n-pentanal components. The milk fraction most susceptible to changes in the presence of light was neutralized whey, whereas resuspended cream was most susceptible to copper exposure. Overall, dialyzed whey appeared to be influenced more than other milk fractions by both light and copper ions.

  3. Ethylene and phenylene bridged polysilsesquioxanes functionalized by amine and thiol groups as adsorbents of volatile organic compounds

    NASA Astrophysics Data System (ADS)

    D?browski, A.; Barczak, M.; Robens, E.; Stolyarchuk, N. V.; Yurchenko, G. R.; Matkovskii, O. K.; Zub, Yu. L.

    2007-04-01

    Ethylene and phenylene bridged polysilsesquioxane xerogels having amine and thiol groups attached to the surface have been obtained by the sol-gel method from 1,2-bis(triethoxysilyl)ethane or 1,4-bis(triethoxysilyl)benzene and functionalized silanes in the presence of an ammonium fluoride catalyst in an ethanol solution. The synthesized samples have a porous structure (700-850 m 2/g) and a high content of functional groups (1.4-1.9 mmol/g). The obtained porous bridged polysilsesquioxanes exhibit a considerable affinity for adsorbing several organic compounds ( n-hexane, n-heptane, benzene, cyclohexane, acetonitrile and triethylamine) from the gas phase. The sample with an ethylene bridge and amino groups in the surface layer has the highest uptake of all compounds. Data from adsorption measurements show that functionalized organosilicon materials can be used as effective adsorbents of organic contaminants from the gas phase.

  4. Liquid layers bound to a gold surface supporting a surface plasmon-polariton

    NASA Astrophysics Data System (ADS)

    Sambles, J. R.; Pollard, J. D.; Bradberry, G. W.

    1987-09-01

    This paper presents a novel use of the surface plasmon-polariton at the surface of a gold film to allow a study of the progressive thickening of an organic liquid film condensing on the gold. The vapour is supplied by an effectively infinite liquid reservoir some 4 mm below the observation height. For methanol, n-hexane and n-heptane equilibrium thicknesses of order 16 nm, 26 nm and 28 nm respectively, are obtained, while for ethanol there appears to be continual growth to a bulk condensed phase. The data can be reconciled in the most general terms with theories of Van der Waal's bonding between thin liquid layers and a plane surface. Currently however there is no detailed theory which would predict the striking difference in behaviour between methanol and ethanol.

  5. [Measurement of diffusion coefficients of polar solvent and nonpolar solvent at infinite dilution in polyethylene].

    PubMed

    Bian, Yu; Li, Ji-Ding; Chen, Cui-Xian; Lü, Shao-Hua; Zhang, Shu-Hua

    2002-09-01

    Gas chromatography is a new, fast, accurate and convenient technique to study the correlation of small molecule solvents and polymer membrane materials. It can measure many parameters of dissolution and diffusing characters of a small molecule in a polymer. The retention times and the peak widths at half-height of five small molecule solvents (n-hexane, n-heptane, n-decane, ethanol and water) in the stationary phase of polyethylene were measured. The diffusion coefficients of the small molecule solvents at infinite dilution were calculated with van Deemter equation. The graph plotted according to the results of the diffusion coefficients of n-decane at infinite dilution vs temperatures agreed with the Arrhenius equation. The variance in the diffusion coefficients at infinite dilution of five small molecule solvents was analyzed according to the differences in molecular mass and polarity. PMID:16358690

  6. Health-hazard evaluation report HETA 85-432-1878, Chevron U. S. A. , Inc. , Port Arthur, Texas

    SciTech Connect

    Markel, H.L.; Wilcox, T.G.

    1988-03-01

    In response to a request, an evaluation was made of cancer incidence and possible hazardous conditions at the Chevron U.S.A. Laboratory. The laboratory performs product analyses and tests on environmental samples to satisfy Environmental Protection Agency requirements. Airborne concentrations of toluene, xylene, n-heptane, and n-hexane were all below the recommended OSHA levels. Five breathing-zone samples and one general area air sample exceeded the NIOSH 0.1 part per million recommended exposure limit for benzene. Some laboratory hoods did not meet minimum requirements to maintain contaminant concentrations below exposure limits. Deaths due to all malignant neoplasms were not found to be elevated. There was a statistically significant excess of rectal cancer and three deaths due to hematopoietic disorders.

  7. Alternatives for Benzene in the Extraction of Bitumen Fume from Exposure Sample Media.

    PubMed

    Sutter, Benjamin; Ravera, Christel; Hussard, Caroline; Langlois, Eddy

    2016-01-01

    Benzene is frequently used to extract collected bitumen fumes from personal sampler substrates. However, this solvent is particularly dangerous because of its carcinogenicity (group 1 of the International Agency for Research on Cancer classification). Therefore, to prevent the exposure of laboratory technicians to benzene during the fume extraction step from samplers, a compromise had to be found to identify a less toxic solvent with the same extraction capacity. To compare the extraction capacities of selected solvents, bitumen fumes were generated in the laboratory from three different batches of road surfacing bitumen collected on dedicated bitumen fume samplers. The samplers were then extracted by benzene and the solvents tested. Of 11 selected solvents less toxic than benzene and used in studies on bitumen and bitumen fume analyses, n-hexane and n-heptane were identified as alternatives to benzene. In particular, the results demonstrated that n-heptane was the best candidate solvent for benzene replacement, due to its extraction efficiency comparable to benzene for the three bitumen fumes tested and its low toxicity, which is highly compatible with benzene replacement. PMID:26400870

  8. An analytical system for the measurement of stable hydrogen isotopes in ambient volatile organic compounds

    NASA Astrophysics Data System (ADS)

    Meisehen, T.; Bühler, F.; Koppmann, R.; Krebsbach, M.

    2015-10-01

    Stable isotope measurements in atmospheric volatile organic compounds (VOCs) are an excellent tool to analyse chemical and dynamical processes in the atmosphere. While up to now isotope studies of VOCs in ambient air have mainly focussed on carbon isotopes, we herein present a new measurement system to investigate hydrogen isotope ratios in atmospheric VOCs. This system, consisting of a gas chromatography pyrolysis isotope ratio mass spectrometer (GC-P-IRMS) and a pre-concentration system, was thoroughly characterised using a VOC test mixture. A precision of better than 9 ‰ (in ? 2H) is achieved for n-pentane, 2-methyl-1,3-butadiene (isoprene), n-heptane, 4-methyl-pentane-2-one (4-methyl-2-pentanone), methylbenzene (toluene), n-octane, ethylbenzene, m/p-xylene and 1,2,4-trimethylbenzene. A comparison with independent measurements via elemental analysis shows an accuracy of better than 9 ‰ for n-pentane, n-heptane, 4-methyl-2-pentanone, toluene and n-octane. Above a minimum required pre-concentrated compound mass the obtained ? 2H values are constant within the standard deviations. In addition, a remarkable influence of the pyrolysis process on the isotope ratios is found and discussed. Reliable measurements are only possible if the ceramic tube used for the pyrolysis is sufficiently conditioned, i.e. the inner surface is covered with a carbon layer. It is essential to verify this conditioning regularly and to renew it if required. Furthermore, influences of a necessary H3+ correction and the pyrolysis temperature on the isotope ratios are discussed. Finally, the applicability to measure hydrogen isotope ratios in VOCs at ambient levels is demonstrated with measurements of outside air on 5 different days in February and March 2015. The measured hydrogen isotope ratios range from -136 to -105 ‰ forn-pentane, from -86 to -63 ‰ for toluene, from -39 to -15 ‰ for ethylbenzene, from -99 to -68 ‰ for m/p-xylene and from -45 to -34 ‰ for o-xylene.

  9. [Determination of serum or plasma alpha-tocopherol by high performance liquid chromatography: optimization of operative models].

    PubMed

    Jezequel-Cuer, M; Le Moël, G; Mounié, J; Peynet, J; Le Bizec, C; Vernet, M H; Artur, Y; Laschi-Loquerie, A; Troupel, S

    1995-01-01

    A previous multicentric study set up by the Société française de biologie clinique has emphasized the usefulness of a standardized procedure for the determination by high performance liquid chromatography of alpha-tocopherol in serum or plasma. In our study, we have tested every step of the different published procedures: internal standard adduct, lipoprotein denaturation and vitamin extraction. Reproducibility of results was improved by the use of tocol as an internal standard when compared to retinol or alpha-tocopherol acetates. Lipoprotein denaturation was more efficient with ethanol addition than with methanol and when the ethanol/water ratio was > or = 0.7. Use of n-hexane or n-heptane gave the same recovery of alpha-tocopherol. When organic solvent/water ratio was > or = 1, n-hexane enabled to efficiently extract, in a one-step procedure, the alpha-tocopherol from both normo and hyperlipidemic sera. Performances of the selected procedure were: detection limit: 0.5 microM--linear range: 750 microM--within run coefficient of variation: 2.03%--day to day: 4.76%. Finally, this pluricentric study allows us to propose an optimised procedure for the determination of alpha-tocopherol in serum or plasma. PMID:8572380

  10. Analysis of polychlorinated biphenyls, polychlorinated dibenzo-p-dioxins and dibenzofurans in particulate and oily films on impervious surfaces.

    PubMed

    Klees, Marcel; Hiester, Ernst; Schmidt, Torsten C

    2015-12-15

    During this study wipe sampling was applied to various impervious surfaces for the determination of polychlorinated biphenyls (PCBs) and polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/PCDFs) area concentrations. To that end, a wipe sampling method based on solvent wetted cotton wipes was evaluated and transfer efficiencies of PCBs and PCDD/PCDFs in particulate films (PFs) and oily liquid films (OFs) during sampling were investigated. For PFs sufficient transfer efficiencies of low concentrated PCB and PCDD/PCDF congeners in 1g/m(2) spiking surrogate were achieved after the first wipe using n-hexane as wetting solvent. Transfer efficiencies for OFs were the highest in the first wipe if n-hexane or n-heptane were used rather than toluene. The spiking experiments of OFs showed a log-linear correlation between the number of wiping procedures and transfer efficiency which indicates that transfer efficiencies were constant in subsequent wipes. Furthermore, it was successfully demonstrated that pressurized liquid extraction is a suitable tool for the extraction of wipe samples. Finally, the feasibility of this wipe sampling method was demonstrated on various impervious surfaces of different origin, and concentration levels of PCBs and PCDD/PCDFs in wipe samples are discussed. Hereby, remarkably high ?CB6 concentrations of up to 1400?g/m(2) (taken at a transformer recycling site) were detected. PMID:26318221

  11. Fuel droplet burning rates at high pressures.

    NASA Technical Reports Server (NTRS)

    Canada, G. S.; Faeth, G. M.

    1973-01-01

    Combustion of methanol, ethanol, propanol-1, n-pentane, n-heptane, and n-decane was observed in air under natural convection conditions, at pressures up to 100 atm. The droplets were simulated by porous spheres, with diameters in the range from 0.63 to 1.90 cm. The pressure levels of the tests were high enough so that near-critical combustion was observed for methanol and ethanol. Due to the high pressures, the phase-equilibrium models of the analysis included both the conventional low-pressure approach as well as high-pressure versions, allowing for real gas effects and the solubility of combustion-product gases in the liquid phase. The burning-rate predictions of the various theories were similar, and in fair agreement with the data. The high-pressure theory gave the best prediction for the liquid-surface temperatures of ethanol and propanol-1 at high pressure. The experiments indicated the approach of critical burning conditions for methanol and ethanol at pressures on the order of 80 to 100 atm, which was in good agreement with the predictions of both the low- and high-pressure analysis.

  12. Gas-Phase Reaction of Hydroxyl Radical with p-Cymene over an Extended Temperature Range.

    PubMed

    Bedjanian, Yuri; Morin, Julien; Romanias, Manolis N

    2015-11-12

    The kinetics of the reaction of OH radicals with p-cymene has been studied in the temperature range of 243-898 K using a flow reactor combined with a quadrupole mass spectrometer: OH + p-cymene ? products. The reaction rate constant was determined as a result of absolute measurements, from OH decay kinetics in excess of p-cymene and employing the relative rate method with OH reactions with n-pentane, n-heptane,1,3-dioxane, HBr, and Br2 as the reference ones. For the rate coefficient of the H atom abstraction channel, the expression k1b = (3.70 ± 0.42) × 10(-11) exp[-(772 ± 72)/T] was obtained over the temperature range of 381-898 K. The total rate constant (addition + abstraction) determined at T = 243-320 K was k1 = (1.82 ± 0.48) × 10(-12) exp[(607 ± 70)/T] or, in a biexponential form, k1 = k1a + k1b = 3.7 × 10(-11) exp(-772/T) + 6.3 × 10(-13) exp(856/T), independent of the pressure between 1 and 5 Torr of helium. In addition, our results indicate that the reaction pathway involving alkyl radical elimination upon initial addition of OH to p-cymene is most probably unimportant. PMID:26473634

  13. Optimization of the anisotropic united atoms intermolecular potential for n-alkanes: improvement of transport properties.

    PubMed

    Nieto-Draghi, Carlos; Ungerer, Philippe; Rousseau, Bernard

    2006-07-28

    The parameters of the anisotropic united atom (AUA) intermolecular potential for n-alkanes originally proposed by Toxvaerd [J. Chem. Phys. 93, 4290 (1990)] [AUA(3)] was optimized by Ungerer et al. [J. Chem. Phys. 112, 5499 (2000)] [AUA(4)] on the basis of equilibrium properties (vapor pressures, vaporization enthalpies, and liquid densities). In this work we analyze the influence of the torsion potential in the internal and collective dynamics of the AUA model. The modified potential [AUA(4m)] preserves all the intermolecular parameters and only explores an increment in the trans-gauche and gauche(+)-gauche(-) transition barrier of the torsion potential. This modification better reproduce different transport properties (shear viscosity, self-diffusion coefficient, and internal relaxation times), keeping the accuracy achieved in our previous work for equilibrium properties. An extensive investigation of the shear viscosity of ethane, n-pentane, n-dodecane, and n-eicosane in a wide range of pressures and temperatures shows that the AUA(4m) improves the accuracy of the original AUA(4), reducing the absolute average deviation from 30% to 14.5%. Finally, the self-diffusion coefficient of n-hexane computed with the new model in the range of 223-333 K and from 0.1 to 295 MPa is in better agreement with respect to the experimental data than the original model. PMID:16942166

  14. Long-Term Incubation Reveals Methanogenic Biodegradation of C5 and C6 iso-Alkanes in Oil Sands Tailings.

    PubMed

    Siddique, Tariq; Mohamad Shahimin, Mohd Faidz; Zamir, Saima; Semple, Kathleen; Li, Carmen; Foght, Julia M

    2015-12-15

    iso-Alkanes are major components of petroleum and have been considered recalcitrant to biodegradation under methanogenic conditions. However, indigenous microbes in oil sands tailings ponds exposed to solvents rich in 2-methylbutane, 2-methylpentane, 3-methylpentane, n-pentane, and n-hexane produce methane in situ. We incubated defined mixtures of iso- or n-alkanes with mature fine tailings from two tailings ponds of different ages historically exposed to different solvents: one, ?10 years old, receiving C5-C6 paraffins and the other, ?35 years old, receiving naphtha. A lengthy incubation (>6 years) revealed iso-alkane biodegradation after lag phases of 900-1800 and ?280 days, respectively, before the onset of methanogenesis, although lag phases were shorter with n-alkanes (?650-1675 and ?170 days, respectively). 2-Methylpentane and both n-alkanes were completely depleted during ?2400 days of incubation, whereas 2-methylbutane and 3-methylpentane were partially depleted only during active degradation of 2-methylpentane, suggesting co-metabolism. In both cases, pyrotag sequencing of 16S rRNA genes showed codominance of Peptococcaceae with acetoclastic (Methanosaeta) and hydrogenotrophic (Methanoregula and Methanolinea) methanogens. These observations are important for predicting long-term greenhouse-gas emissions from oil sands tailings ponds and extend the known range of hydrocarbons susceptible to methanogenic biodegradation in petroleum-impacted anaerobic environments. PMID:26571341

  15. Lactic fermentation to improve the aroma of protein extracts of sweet lupin (Lupinus angustifolius).

    PubMed

    Schindler, Sabrina; Wittig, Maximilian; Zelena, Kateryna; Krings, Ulrich; Bez, Jürgen; Eisner, Peter; Berger, Ralf G

    2011-09-15

    Lupin protein extracts (LPE) are prone to the emission of a beany off-flavour during storage, which confines its application in foods. Fermentation of LPE using several lactic acid bacteria was conducted to reduce off-flavour formation in stored samples. The aroma profile of untreated LPE was compared to those of fermented protein extracts (LPEF). Hexanal and n-hexanol were used as indicator substances of progressing lipid oxidation. The most powerful odourants were evaluated by GC-olfactometry-flavour dilution analysis and identified according to their mass spectra, odour descriptions, and retention indices. Twenty two volatile substances with dilution factors equal to or higher than 100 were determined in both LPE and LPEF, amongst them n-pentanal, n-hexanal, 1-pyrroline, dimethyl trisulfide, 1-octen-3-one, 3-octen-2-one, 1-octen-3-ol, and ?-damascenone. The aroma profile was significantly modified by the fermentation process and the off-flavours were reduced and/or masked by newly formed compounds. PMID:25212139

  16. Stable Carbon Isotope Ratios and Mixing Ratios of Several VOC Including n-Hexane, Benzene, Toluene, p-Xylene, n-Octane, and n-Decane Measured During the Border Air Quality Study Campaign (June-July, 2007)

    NASA Astrophysics Data System (ADS)

    Kornilova, A.; Moukhtar, S.; Huang, L.; Rudolph, J.

    2008-12-01

    Many important secondary pollutants are formed during the oxidation of Volatile Organic Compounds (VOC) in the atmosphere. These organic compounds can contribute significant mass to atmospheric particulate matter (PM) and therefore impact physical properties and composition of aerosols. Despite numerous studies, the formation processes for atmospheric PM are still not well understood. While there have been very extensive laboratory investigations of PM formation, nearly all of these studies have been conducted at VOC concentrations which exceed ambient atmospheric levels by several orders of magnitude. Consequently there is substantial uncertainty in the extrapolation of laboratory results to the atmosphere. Recently it has been demonstrated that stable carbon isotopic composition measurements can be very valuable in providing increased insight into the chemical and transport processes of VOC in the troposphere. Studies showed that isotope ratio measurements could aid in the determination of photochemical processing of individual VOC. It is expected that applying isotope measurements to studies of VOC oxidation products in the atmosphere will allow to establish quantitative relationship between the amount of precursor oxidized and the concentration of secondary pollutants formed during this process. Thus, the yield of secondary organic aerosols (SOA) from this reaction can be calculated. A cartridge technique was developed for field sampling of VOC and subsequent laboratory analysis by gas chromatography coupled with isotope ratio mass spectrometry. It was first implemented during the BAQS field study (June-July, 2007) parallel to PM sampling. Stable carbon isotopic composition and concentrations of several VOC were determined and compared to those of PM. The results of these measurements will be presented and discussed.

  17. Monitoring of Selected Skin-Borne Volatile Markers of Entrapped Humans by Selective Reagent Ionization Time of Flight Mass Spectrometry in NO+ Mode

    PubMed Central

    2014-01-01

    Selective reagent ionization time-of-flight mass spectrometry with NO+ as the reagent ion (SRI-TOF-MS (NO+)) was applied for near real-time monitoring of selected skin-borne constituents which are potential markers of human presence. The experimental protocol involved a group of 10 healthy volunteers enclosed in a body plethysmography chamber mimicking the entrapment environment. A total of 12 preselected omnipresent in human scent volatiles were quantitatively monitored. Among them there were six aldehydes (n-propanal, n-hexanal, n-heptanal, n-octanal, n-nonanal, and 2 methyl 2-propenal), four ketones (acetone, 2-butanone, 3-buten-2-one, and 6-methyl-5-hepten-2-one), one hydrocarbon (2-methyl 2-pentene), and one terpene (DL-limonene). The observed median emission rates ranged from 0.28 to 44.8 nmol × person–1 × min–1 (16–1530 fmol × cm–2 × min–1). Within the compounds under study, ketones in general and acetone in particular exhibited the highest abundances. The findings of this study provide invaluable information about formation and evolution of a human-specific chemical fingerprint, which could be used for the early location of entrapped victims during urban search and rescue operations (USaR). PMID:24611620

  18. Interpolation between State Points in the Simulated Perturbation Contributions of Polymer Solutions

    NASA Astrophysics Data System (ADS)

    Vahid, Amir; Gray, Neil H.; Elliott, J. Richard

    2009-03-01

    Polymeric mixtures of hydrocarbons, alcohols have been simulated with discontinuous potential models to characterize the Helmholtz energy of the repulsive reference fluids (A0) along with the first and second order perturbation contributions (A1, A2) as functions of density and composition. Taken together, these terms generate a complete equation of state for the mixture, including temperature effects as well as density and composition. The specific hydrocarbons studied were methane, ethane, propane, n-butane, n-hexane, n-heptane, n-decane, and benzene. The specific alcohols were water, methanol, ethanol, n-propanol, and n-octanol. Unfortunately, a slight inconsistency was encountered when the trend observed for these small molecules was extrapolated to the long chain limit. Therefore, we extend the analysis to mixtures of n-alkanes, branched hydrocarbons, and aromatics with polymeric molecules of: n-alkanes, ethyl-styrenes, ethyl-propylenes, and isoprenes. The perturbation contributions can be accurately characterized by van der Waals mixing rules and compared with the MCSL SAFT and Guggenheim-Staverman theories.

  19. [The study of vapor-liquid equilibria for polymer/solvents by using gas-liquid chromatography].

    PubMed

    Xie, J

    1999-05-01

    The infinite dilution weight fraction activity coefficient, omega 1 infinity, and Flory-Huggins interaction parameter, chi, have been determined for systems of polydimethylsiloxane (PDMS)/solvents and polymethyl-methacrylate (PMMA)/solvents by using gas chromatography from 58 degrees C to 180 degrees C. The solvents include styrene, acetone, ethyl ether, methanol, ethanol, acetic acid, trichloromethane, tetrahydrofuran and ethyl acetate in PDMS/solvent systems and n-hexane, n-heptane, cyclohexane, benzene, toluene, ethyl benzene, styrene, acetone, ethyl ether, methanol, ethanol, methyl methacrylate(MMA), trichloromethane, tetrahydrofuran and ethyl acetate in the PMMA/solvent systems. The results showed that omega 1 infinity and chi were decreased with the increase of temperature in the range from 58 degrees C to 180 degrees C. The study showed that UNIFAC and UNIFAC-FV models could not all be used to estimate omega 1 infinity of the solvents in PMMA/solvent systems. Therefore, UNIFAC and UNIFAC-FV models must be corrected or other models must be used. PMID:12549114

  20. Separation and aquatic toxicity of enantiomers of the organophosphorus insecticide trichloronate.

    PubMed

    Liu, Weiping; Lin, Kunde; Gan, Jianying

    2006-09-01

    Many of the organophosphorus pesticides (OPs) currently used are chiral and therefore consist of mixture of enantiomers. Despite the fact that the biological processes of chiral pesticides are enantioselective, the acute aquatic toxicity of chiral OPs with respect to enantioselectivity has so far received limited research. In this study, the enantiomeric separation and acute aquatic toxicity of trichloronate were investigated. Baseline enantioseparation of trichloronate was successfully achieved using high-performance liquid chromatography on a Chiralcel OJ column, with a mobile phase of n-hexane/n-heptane/ethanol (90/5/5, v/v/v) at the flow rate of 1.0 ml min(-1) and room temperature. The resolved enantiomers were characterized for their optical rotation and by gas chromatography coupled with mass spectrometry. Significant differences were found between the enantiomers in acute aquatic toxicity to Ceriodaphnia dubia and Daphnia magna. The (-)-trichloronate was 8-11 times more toxic to the test organisms than its (+)-form, while the racemate showed intermediate toxicity. These results suggest that assessment of the environmental safety of chiral OPs should take stereospecificity into consideration. PMID:16845672

  1. Observed trends in ambient concentrations of C 2-C 8 hydrocarbons in the United Kingdom over the period from 1993 to 2004

    NASA Astrophysics Data System (ADS)

    Dollard, G. J.; Dumitrean, P.; Telling, S.; Dixon, J.; Derwent, R. G.

    Hourly measurements of up to 26 C 2-C 8 hydrocarbons have been made at eight urban background sites, three urban-industrial sites, a kerbside and a rural site in the UK from 1993 onwards up until the end of December 2004. Average annual mean benzene and 1,3-butadiene concentrations at urban background locations have declined at about -20% per year and the observed declines have exactly mimicked the inferred declines in benzene and 1,3-butadiene emissions over the same period. Ninety-day rolling mean concentrations of ethylene, propylene, n- and i-butane, n- and i-pentane, isoprene and propane at urban and rural sites have also declined steadily by between -10% and -30% per year. Rolling mean concentrations of acetylene, 2- and 3-methylpentane, n-hexane, n-heptane, cis- and trans-but-2-ene, cis- and trans-pent-2-ene, toluene, ethylbenzene and o-, m- and p-xylene at a roadside location in London have all declined at between -14% and -21% per year. These declines demonstrate that motor vehicle exhaust catalysts and evaporative canisters have effectively and efficiently controlled vehicular emissions of hydrocarbons in the UK. Urban ethane concentrations arising largely from natural gas leakage have remained largely unchanged over this same period.

  2. Effects of organic solvents on immobilized lipase in pectin microspheres.

    PubMed

    Costas, L; Bosio, V E; Pandey, A; Castro, G R

    2008-12-01

    Lipase from Brevibacillus agri 52 was found stable up to 90% diethylenglycol (DEG), glycerol (GLY), and 1,2 propanediol (1,2 PRO) at 37 degrees C for 1 h and the stability was reduced only approximately 20% after 12 h incubation, but in 40% dimethylsulfoxide (DMSO), lipase activity was stable only for 1 h. Inhibition of the biocatalysts with dimethylformamide (DMF) was detected at 20% solvent concentration. In water immiscible systems, the stability of lipase in n-hexane, n-tetradecane and n-heptane resembles the water activity, but in the presence of isobutanol, 1-hexanol, and butylbutirate, the stability was significantly reduced. Lipase 52 precipitates in the presence of 50% acetone or ethanol/water mixtures, but enzymatic activity was partially recovered by adding 20% GLY, DEG, 1,2 PRO, or DMSO to the reaction mixture. Furthermore, by increasing DEG in 70% DMF/DEG mixtures, the lipase activity was protected. Encapsulation of lipase in pectin gels cross-linked with calcium ions brings three to four times more enzymatic activity in 70% water miscible organic solvents compared to aqueous systems. PMID:18543116

  3. Comparative study of free and immobilized lipase from Bacillus aerius and its application in synthesis of ethyl ferulate.

    PubMed

    Saun, Nitin Kumar; Narwal, Sunil Kumar; Dogra, Priyanka; Chauhan, Ghanshyam Singh; Gupta, Reena

    2014-01-01

    In the present study, a purified lipase from Bacillus aerius immobilized on celite matrix was used for synthesis of ethyl ferulate. The celite-bound lipase exposed to glutaraldehyde showed 90.02% binding efficiency. It took two hours to bind maximally onto the support. The pH and temperature optima of the immobilized lipase were same as those of free enzyme i.e 9.5 and 55°C. Among different substrates both free and immobilized lipase showed maximum affinity towards p-nitrophenyl palmitate (p-NPP). The lipase activity was found to be stimulated in the presence of Mg(2+) in case of free enzyme while Zn(2+) and Fe(3+) showed stimulatory effect on immobilized lipase whereas salt ions as well as chelating agents inhibited activity of both free and immobilized lipase. Maximum enzyme activity was observed in n-hexane as organic solvent followed by n-heptane for both free and immobilized lipase, however CCl4, acetone and benzene inhibited the enzyme activity. Moreover, all the selected detergents (SDS, Triton X-100, Tween 80 and Tween 20) had an inhibitory effect on both free and immobilized enzyme activity. The celite bound lipase (1.5%) efficiently performed maximum esterification (2.51 moles/l) of ethanol and ferulic acid (100 mM each, at a molar ratio of 1:3) when incubated at 55°C for 48 h resulting in the formation of ester ethyl ferulate. PMID:25099909

  4. Investigation of thermodynamic properties of poly(methyl methacrylate-co-n-butylacrylate-co-cyclopentyl styryl-polyhedral oligomeric silsesquioxane) by inverse gas chromatography.

    PubMed

    Zou, Qi-Chao; Zhang, Shi-Ling; Wang, Shi-Min; Wu, Li-Min

    2006-10-01

    The thermodynamic properties of poly(methyl methacrylate-co-butyl acrylate-co-cyclo -pentylstyryl polyhedral oligomeric silsesquioxane) (poly(MMA-co-BA-co-styryl-POSS)) were investigated by means of inverse gas chromatography (IGC) using 20 different kinds of solvents as the probes. Some thermodynamic parameters, such as molar heats of sorption, weight fraction activity coefficient, Flory-Huggins interaction parameter, partial molar heats of mixing and solubility parameter were obtained to judge the interactions between POSS-contained polymers and solvents and the solubility of the polymers in these solvents. It was found that acetates, aromatic hydrocarbons and hydrocarbon halides were good solvents, n-hexane, ethanol, n-propanol, n-butanol and n-pentanol were moderate solvents, while n-heptane, n-octane, n-nonane, n-decane and methanol were poor solvents for all POSS-contained polymers within the experimental temperature range. Incorporation of POSS in polymer increased the solubility of polymers in solvents, and the more the POSS in polymer was, the better the solubility was and stronger the hydrogen bonding interaction was, but the POSS content in polymers seemed to have no obvious influence on the solubility parameter of polymers. PMID:16846607

  5. Preparation of spherically agglomerated crystals of aminophylline.

    PubMed

    Kawashima, Y; Aoki, S; Takenaka, H; Miyake, Y

    1984-10-01

    The spherically agglomerated crystals of aminophylline (theophylline-ethylenediamine complex) can be compounded directly into pharmaceutical formulations without further processing, e.g., granulation. Such crystals were prepared by mixing theophylline and ethylenediamine in a partially miscible solvent system, i.e., organic solvent-ethanol-water. The organic solvents used were chloroform, 1-hexanol, isopropyl acetate, isobutyl acetate, isoamyl acetate, benzene, toluene, n-hexane, or n-heptane. Spherical crystallization depended upon the solubility of theophylline in the solvent mixture. The resultant agglomerated crystals were identical with the theophylline-ethylenediamine complex by IR, X-ray, and differential scanning calorimetry analyses, and was the alpha-, beta-, or gamma-form when the water of crystallization was less than or equal to 0.5, 1.0, and 2.5 mol, respectively. When the amount of ethylenediamine used was less than 1.1 mL (0.0165 mol), the resultant agglomerated crystals were converted to anhydrous theophylline by washing with ethanol. When water was added to the system (greater than or equal to 0.3 mL, i.e., 0.0167 mol), water was occluded in the resultant agglomerates as water of crystallization. Ethylenediamine content in the agglomerated crystals could be controlled by changing the amount of ethylenediamine added in the crystallization solvent. PMID:6502490

  6. QCM gas phase detection with ceramic materials--VOCs and oil vapors.

    PubMed

    Latif, Usman; Rohrer, Andreas; Lieberzeit, Peter A; Dickert, Franz L

    2011-06-01

    Titanate sol-gel layers imprinted with carbonic acids were used as sensitive layers on quartz crystal microbalance. These functionalized ceramics enable us detection of volatile organic compounds such as ethanol, n-propanol, n-butanol, n-hexane, n-heptane, n-/iso-octane, and n-decane. Variation of the precursors (i.e., tetrabutoxy titanium, tetrapropoxy titanium, tetraethoxy titanium) allows us to tune the sensitivity of the material by a factor of 7. Sensitivity as a function of precursors leads to selective inclusion of n-butanol vapors down to 1 ppm. The selectivity of materials is optimized to differentiate between isomers, e.g., n- and iso-octane. The results can be rationalized by correlating the sensor effects of hydrocarbons with the Wiener index. A mass-sensitive sensor based on titanate layer was also developed for monitoring emanation of degraded engine oil. Heating the sensor by a meander avoids vapor condensation. Thus, a continuously working oil quality sensor was designed. PMID:21301823

  7. Biodiesel production using waste frying oil

    SciTech Connect

    Charpe, Trupti W.; Rathod, Virendra K.

    2011-01-15

    Research highlights: {yields} Waste sunflower frying oil is successfully converted to biodiesel using lipase as catalyst. {yields} Various process parameters that affects the conversion of transesterification reaction such as temperature, enzyme concentration, methanol: oil ratio and solvent are optimized. {yields} Inhibitory effect of methanol on lipase is reduced by adding methanol in three stages. {yields} Polar solvents like n-hexane and n-heptane increases the conversion of tranesterification reaction. - Abstract: Waste sunflower frying oil is used in biodiesel production by transesterification using an enzyme as a catalyst in a batch reactor. Various microbial lipases have been used in transesterification reaction to select an optimum lipase. The effects of various parameters such as temperature, methanol:oil ratio, enzyme concentration and solvent on the conversion of methyl ester have been studied. The Pseudomonas fluorescens enzyme yielded the highest conversion. Using the P. fluorescens enzyme, the optimum conditions included a temperature of 45 deg. C, an enzyme concentration of 5% and a methanol:oil molar ratio 3:1. To avoid an inhibitory effect, the addition of methanol was performed in three stages. The conversion obtained after 24 h of reaction increased from 55.8% to 63.84% because of the stage-wise addition of methanol. The addition of a non-polar solvent result in a higher conversion compared to polar solvents. Transesterification of waste sunflower frying oil under the optimum conditions and single-stage methanol addition was compared to the refined sunflower oil.

  8. A rapid and efficient method for directed screening of lipase-producing Burkholderia cepacia complex strains with organic solvent tolerance from rhizosphere.

    PubMed

    Shu, Zhengyu; Lin, Ruifeng; Jiang, Huan; Zhang, Yanfeng; Wang, Mingzi; Huang, Jianzhong

    2009-06-01

    Lipase from Burkholderia cepacia strain is one of the most versatile biocatalysts and is used widely in many biotechnological application fields including detergent additives, the resolution of racemic compounds, etc. Based on the known whole genomic information of B. cepacia strain, both ampicillin and kanamycin were added to the TB-T medium to screen B. cepacia complex stains from rhizosphere soil samples. The selected colonies from the modified TB-T medium were then qualitatively determined the ability to produce extracellular lipase on the rhodamine B-olive oil agar plates. A total of 35 lipolytic pseudo-B. cepacia complex strains were isolated and the positive rate of lipolytic bacteria was 65%. Among them, 15 pseudo-B. cepacia complex strains showed tolerance to benzene, n-hexane and n-heptane at concentration of 10% (V/V) and were identified by the recA gene sequence. All of the 14 lipolytic bacteria were identified as B. cepacia complex strains except that the recA gene sequence of one lipolytic bacterium, strain ZMB009, was not obtained. PMID:19447345

  9. High pressure droplet burning experiments in reduced gravity

    NASA Technical Reports Server (NTRS)

    Chauveau, Christian; Goekalp, Iskender

    1995-01-01

    A parametric investigation of single droplet gasification regimes is helpful in providing the necessary physical ideas for sub-grid models used in spray combustion numerical prediction codes. A research program has been initiated at the LCSR to explore the vaporization regimes of single and interacting hydrocarbon and liquid oxygen droplets under high pressure conditions. This paper summarizes the status of the LCSR program on the high pressure burning of single fuel droplets; recent results obtained under normal and reduced gravity conditions with suspended droplets are presented. In the work described here, parabolic flights of the CNES Caravelle is used to create a reduced gravity environment of the order of 10(exp -2) g(sub O). For all the droplet burning experiments reported here, the suspended droplet initial diameters are scattered around 1.5 mm; and the ambient air temperature is 300 K. The ambient pressure is varied between 0.1 MPa and 12 MPa. Four fuels are investigated: methanol (Pc = 7.9 MPa), n-heptane (Pc = 2.74 MPa), n-hexane (Pc = 3.01 MPa) and n-octane (Pc = 2.48 MPa).

  10. n-Aldehydes (C6-C10) in snow samples collected at the high alpine research station Jungfraujoch during CLACE 5

    NASA Astrophysics Data System (ADS)

    Sieg, K.; Starokozhev, E.; Fries, E.; Sala, S.; Püttmann, W.

    2009-03-01

    Samples of freshly fallen snow were collected at the high alpine research station Jungfraujoch, Switzerland, during the Cloud and Aerosol Characterization Experiments (CLACE) 5 in February and March 2006. Sampling was carried out on the Sphinx platform. Headspace-solid-phase-dynamic extraction (HS-SPDE) combined with gas chromatography/mass spectrometry (GC/MS) was used to quantify C6-C10 n-aldehydes in the snow samples. The most abundant n-aldehyde was n-hexanal (median concentration 1.324 ?g L-1) followed by n-nonanal, n-decanal, n-octanal and n-heptanal (median concentrations 1.239, 0.863, 0.460, and 0.304 ?g L-1, respectively). A wide range of concentrations was found among individual snow samples, even for samples taken at the same time. Higher median concentrations of all n-aldehydes were observed when air masses reached Jungfraujoch from the north-northwest in comparison to air masses arriving from the southeast-southwest. Results suggest that the n-aldehydes detected most likely are of direct and indirect biogenic origin, and that they entered the snow through the particle phase.

  11. Infrared band intensities of saturated hydrocarbons

    NASA Technical Reports Server (NTRS)

    Pinkley, L. W.; Sethna, P. P.; Williams, D.

    1978-01-01

    Kramers-Kronig analysis is applied to measured values of spectral reflectance at near-normal incidence to determine the real and the imaginary parts of the complex index of refraction for methane, ethane, propane, n-butane, n-hexane, n-heptane, and n-decane in the liquid state. The results indicate that the strengths of the characteristic bands as measured by the integral of the imaginary part are roughly constant for all the liquid alkanes except for methane. The intensity of the CH valence vibration bands in the spectra of the alkanes except methane is directly proportional to the number of CH groups per unit volume. The relations for the intensity of the bands due to CH2 and CH3 deformations are examined. Characteristic band intensities of the type established for NH4(+) and SO4(2-) groups in solutions and crystals cannot be extended to the more closely coupled CH2 and CH3 groups in alkane molecules.

  12. Thermochemistry of C7H16 to C10H22 alkane isomers: primary, secondary, and tertiary C-H bond dissociation energies and effects of branching.

    PubMed

    Hudzik, Jason M; Bozzelli, Joseph W; Simmie, John M

    2014-10-01

    Standard enthalpies of formation (?H°f 298) of methyl, ethyl, primary and secondary propyl, and n-butyl radicals are evaluated and used in work reactions to determine internal consistency. They are then used to calculate the enthalpy of formation for the tert-butyl radical. Other thermochemical properties including standard entropies (S°(T)), heat capacities (Cp(T)), and carbon-hydrogen bond dissociation energies (C-H BDEs) are reported for n-pentane, n-heptane, 2-methylhexane, 2,3-dimethylpentane, and several branched higher carbon number alkanes and their radicals. ?H°f 298 and C-H BDEs are calculated using isodesmic work reactions at the B3LYP (6-31G(d,p) and 6-311G(2d,2p) basis sets), CBS-QB3, CBS-APNO, and G3MP2B3 levels of theory. Structures, moments of inertia, vibrational frequencies, and internal rotor potentials are calculated at the B3LYP/6-31G(d,p) level for contributions to entropy and heat capacities. Enthalpy calculations for these hydrocarbon radical species are shown to have consistency with the CBS-QB3 and CBS-APNO methods using all work reactions. Our recommended ideal gas phase ?H°f 298 values are from the average of all CBS-QB3, CBS-APNO, and for G3MP2B3, only where the reference and target radical are identical types, and are compared with literature values. Calculated values show agreement between the composite calculation methods and the different work reactions. Secondary and tertiary C-H bonds in the more highly branched alkanes are shown to have bond energies that are several kcal mol(-1) lower than the BDEs in corresponding smaller molecules often used as reference species. Entropies and heat capacities are calculated and compared to literature values (when available) when all internal rotors are considered. PMID:25180943

  13. Transferable Potentials for Phase Equilibria. 4. United-Atom Description of Linear and Branched Alkenes and Alkylbenzenes

    SciTech Connect

    WICK,COLLIN D.; MARTIN,MARCUS G.; SIEPMANN,J. ILJA

    2000-07-12

    The Transferable Potentials for Phase Equilibria-United Atom (TraPPE-UA) force field for hydrocarbons is extended to alkenes and alkylbenzenes by introducing the following pseudo-atoms: CH{sub 2}(sp{sup 2}), CH(sp{sup 2}), CH(aro), R-C(aro) for the link to aliphatic side chains, and C(aro) for the link of two benzene rings. In this united-atom force field, the nonbonded interactions of the hydrocarbon pseudo-atoms are solely governed by Lennard-Jones 12-6 potentials, and the Lennard-Jones well depth and size parameters for the new pseudo-atoms were determined by fitting to the single-component vapor-liquid phase equilibria of a few selected model compounds. Configurational-bias Monte Carlo simulations in the NVT version of the Gibbs ensemble were carried out to calculate the single-component vapor-liquid coexistence curves for ethene, propene, 1-butene, trans- and cis-2-butene. 2-methylpropene, 1,5-hexadiene, 1-octene, benzene, toluene, ethylbenzene, propylbenzene, isopropylbenzene, o-, m-, and p-xylene, and naphthalene. The phase diagrams for the binary mixtures of (supercritical) ethene/n-heptane and benzene/n-pentane were determined from simulations in the NpT Gibbs ensemble. Although the TraPPE-UA force field is rather simple and makes use of relatively few different pseudo-atoms, its performance, as judged by comparisons to other popular force fields and available experimental data, is very satisfactory.

  14. n-Aldehydes (C6-C10) in snow samples collected at the high alpine research station Jungfraujoch during CLACE 5

    NASA Astrophysics Data System (ADS)

    Sieg, K.; Starokozhev, E.; Fries, E.; Sala, S.; Püttmann, W.

    2009-04-01

    C6-C10 n-aldehydes were analyzed in samples of freshly fallen snow collected at the high alpine research station Jungfraujoch, Switzerland, during the Cloud and Aerosol Characterization Experiments (CLACE) 5 in February and March 2006. Sampling was carried out on the Sphinx platform. Headspace - solid phase dynamic extraction (HS-SPDE) combined with gas chromatography/mass spectrometry (GC/MS) was used to quantify n-aldehydes in melted snow samples. n-Hexanal was identified as the most abundant n-aldehyde (median concentration 1.324 µg L-1) followed by n-nonanal, n-decanal, n-octanal and n-heptanal (median concentrations 1.239, 0.863, 0.460 and 0.304 µg L-1, respectively). A wide range of concentrations of n-aldehydes was found in snow samples from Jungfraujoch, even for samples collected at the same time during the same snowfall event. According to their physical and chemical characteristics, n-aldehydes are expected to be primarily linked to aerosol particles in the atmosphere suggesting the uptake of n-aldehydes into snow via the particle phase. Particle scavenging can occur during snow formation in clouds. The high concentration variations of the n-aldehydes among the snow samples can be explained assuming that aerosol particles, which are loaded with n-aldehydes, are heterogeneously distributed throughout the snow samples. Higher median concentrations of all n-aldehydes were observed when air masses reached Jungfraujoch from the north-northwest in comparison to air masses arriving from the southeast-southwest. The sources of atmospheric n-aldehydes present at Jungfraujoch are most likely to be related to direct and indirect biogenic emissions. The presence of n-aldehydes as semivolatile constituents of direct biogenic emissions from vegetation has been reported previously in studies of Ciccioli et al. [1], Yokouchi et al. [2] and Kesselmeier and Staudt [3]. The distribution pattern of the n-aldehydes in emissions from vegetation largely matches with the n-aldehyde pattern found in snow collected at Jungfraujoch. One exception is the significantly higher proportion of n-hexanal in the Jungfraujoch samples compared to vegetation emission. Additionally, indirect biogenic emissions can contribute to the atmospheric concentrations of n-aldehydes through oxidation of precursor compounds of biogenic origin. In this context, Moise and Rudich [4] and Thornberry and Abbatt [5] proposed the preferential formation of n-nonanal and n-hexanal from the cleavage by ozonolysis of double bonds in unsaturated fatty acids (namely oleic acid and linoleic acids). The predominance of n-hexanal and n-nonanal among the C6-C10 n-aldehydes in the snow samples collected at Jungfraujoch during CLACE 5 is therefore an argument for the formation of the aldehydes through oxidation of unsaturated fatty acids in the atmosphere. Anthropogenic emissions of n-aldehydes i.e. from fossil fuel burning are thought to be negligible in the air masses reaching Jungfraujoch. References: [1] P. Ciccioli, E. Brancaleoni, M. Frattoni, A. Cecinato, A. Brachetti, Atmos. Environ., Part A 27 (1993) 1891. [2] Y. Yokouchi, H. Mukai, K. Nakajima, Y. Ambe, Atmos. Environ., Part A 24 (1990) 439. [3] J. Kesselmeier, M. Staudt, J. Atmos. Chem. 33 (1999) 23. [4] T. Moise, Y. Rudich, J. Phys. Chem. 106 (2002) 6469. [5] T. Thornberry, J.P.D. Abbatt, Phys. Chem. Chem. Phys. 6 (2004) 84.

  15. Investigating the validity of the Knudsen prescription for diffusivities in a mesoporous covalent organic framework

    SciTech Connect

    Krishna, Rajamani; van Baten, Jasper M.

    2011-04-27

    Molecular dynamics (MD) simulations were performed to determine the self-diffusivity (Di,self) and the Maxwell–Stefan diffusivity (ÐI) of hydrogen, argon, carbon dioxide, methane, ethane, propane, n-butane, n-pentane, and n-hexane in BTP-COF, which is a covalent organic framework (COF) that has one-dimensional 3.4-nm-sized channels. The MD simulations show that the zero-loading diffusivity (ÐI(0)) is consistently lower, by up to a factor of 10, than the Knudsen diffusivity (Di,Kn) values. The ratio ÐI(0)/Di,Kn is found to correlate with the isosteric heat of adsorption, which, in turn, is a reflection of the binding energy for adsorption on the pore walls: the stronger the binding energy, the lower the ratio ÐI(0)/Di,Kn. The diffusion selectivity, which is defined by the ratio D1,self/D2,self for binary mixtures, was determined to be significantly different from the Knudsen selectivity (M2/M1)1/2, where MI is the molar mass of species i. For mixtures in which component 2 is more strongly adsorbed than component 1, the expression (D1,self/D2,self)/(M2/M1)1/2 has values in the range of 1–10; the departures from the Knudsen selectivity increased with increasing differences in adsorption strengths of the constituent species. The results of this study have implications in the modeling of diffusion within mesoporous structures, such as MCM-41 and SBA-15.

  16. [Pollution characteristics and ozone formation potential of ambient VOCs in winter and spring in Xiamen].

    PubMed

    Xu, Hui; Zhang, Han; Xing, Zhen-yu; Deng, Jun-jun

    2015-01-01

    Air samples were collected at urban and rural sites in Xiamen from January to April 2014. The concentrations of 48 ambient volatile organic compounds (VOC) species were measured by the method of cryogenic pre-concentrator and gas chromatography-mass spectrometry (GC/MS). The ozone formation potential (OFP) of VOCs was also calculated with the method of maximum incremental reactivity (MIR). The results showed that the average mixing ratios of VOCs in winter were 11.13 x 10(-9) and 7.17 x 10(-9) at urban and rural sites, respectively, and those in spring were 24.88 x 10(-9) and 11.27 x 10(-9) at urban and rural sites, respectively. At both sites, alkanes contributed the most to VOCs, followed by aromatics and alkenes. The ratios of B/T showed that vehicle and solvent evaporation were the main sources of VOCs at urban site. While at rural site, transport of anthropogenic sources was another important source of VOCs besides local biomass emissions. Ten main components including propene, n-butane, i-butane, n-pentane, i-pentane, n-hexane, benzene, toluene, ethylbenzene and m/p-xylene accounted for 61.57% and 45.83% of total VOCs at urban and rural sites in winter, respectively, and 62.83% and 53.74% at urban and rural sites in spring, respectively. Aromatics contributed the most to total OFP, followed by alkenes. Alkanes contributed the least to OFP with the highest concentration. C3, C4 alkenes and aromatics were found to be the more reactive species with relatively high contributions to ozone formation in Xiamen. Comparing the average MIR of VOCs at the two sites, it was found that the reactivity of VOCs at rural site was higher than that at urban site. PMID:25898641

  17. Molecular dynamics averaging of Xe chemical shifts in liquids

    NASA Astrophysics Data System (ADS)

    Jameson, Cynthia J.; Sears, Devin N.; Murad, Sohail

    2004-11-01

    The Xe nuclear magnetic resonance chemical shift differences that afford the discrimination between various biological environments are of current interest for biosensor applications and medical diagnostic purposes. In many such environments the Xe signal appears close to that in water. We calculate average Xe chemical shifts (relative to the free Xe atom) in solution in eleven liquids: water, isobutane, perfluoro-isobutane, n-butane, n-pentane, neopentane, perfluoroneopentane, n-hexane, n-octane, n-perfluorooctane, and perfluorooctyl bromide. The latter is a liquid used for intravenous Xe delivery. We calculate quantum mechanically the Xe shielding response in Xe-molecule van der Waals complexes, from which calculations we develop Xe (atomic site) interpolating functions that reproduce the ab initio Xe shielding response in the complex. By assuming additivity, these Xe-site shielding functions can be used to calculate the shielding for any configuration of such molecules around Xe. The averaging over configurations is done via molecular dynamics (MD). The simulations were carried out using a MD technique that one of us had developed previously for the simulation of Henry's constants of gases dissolved in liquids. It is based on separating a gaseous compartment in the MD system from the solvent using a semipermeable membrane that is permeable only to the gas molecules. We reproduce the experimental trends in the Xe chemical shifts in n-alkanes with increasing number of carbons and the large chemical shift difference between Xe in water and in perfluorooctyl bromide. We also reproduce the trend for a given solvent of decreasing Xe chemical shift with increasing temperature. We predict chemical shift differences between Xe in alkanes vs their perfluoro counterparts.

  18. METHYL KETONE METABOLISM IN HYDROCARBON-UTILIZING MYCOBACTERIA

    PubMed Central

    Lukins, H. B.; Foster, J. W.

    1963-01-01

    Lukins, H. B. (University of Texas, Austin) and J. W. Foster. Methyl ketone metabolism in hydrocarbon-utilizing mycobacteria. J. Bacteriol. 85: 1074–1087. 1963.—Species of Mycobacterium especially M. smegmatis 422, produced the homologous methyl ketones during the oxidation of propane, n-butane, n-pentane, or n-hexane. A carrier-trapping experiment demonstrated the formation of 2-undecanone, as well as 1,11-undecanedioic acid, during the oxidation of undecane-1-C14. Aliphatic alkane-utilizing mycobacteria were able to grow at the expense of several aliphatic methyl ketones as sole sources of carbon. Other ketones which did not support growth were oxidized by resting bacterial suspensions. M. smegmatis 422 cells grown on propane or acetone were simultaneously adapted to oxidize both substrates, as well as n-propanol. n-Propanol cells were unadapted to propane or acetone. Acetone produced from propane in a medium enriched in D2O contained a negligible quantity of D, presumably eliminating propylene as an intermediate in the oxidation. Cells grown at the expense of alkanes or methyl ketones in the presence of O218 had a higher content of O18 than did cells grown on terminally oxidized compounds, e.g., primary alcohols or fatty acids. An oxygenase reaction is postulated for the attack on methyl ketones. Acetol was isolated and characterized as an oxidation product of acetone by M. smegmatis 422. Acetol-grown cells had a higher O18 content than did n-propanol cells, and its utilization appears to involve at least one oxygenase reaction. Acetol produced from acetone in the presence of O218 was not enriched in the isotope, indicating the occurrence of exchange reactions or of oxygenation reactions at a later stage in the assimilation of acetone and acetol. PMID:14043998

  19. 13C NMR studies of hydrocarbon guests in synthetic structure H gas hydrates: experiment and computation.

    PubMed

    Lee, Jong-Won; Lu, Hailong; Moudrakovski, Igor L; Ratcliffe, Christopher I; Ohmura, Ryo; Alavi, Saman; Ripmeester, John A

    2011-03-10

    (13)C NMR chemical shifts were measured for pure (neat) liquids and synthetic binary hydrate samples (with methane help gas) for 2-methylbutane, 2,2-dimethylbutane, 2,3-dimethylbutane, 2-methylpentane, 3-methylpentane, methylcyclopentane, and methylcyclohexane and ternary structure H (sH) clathrate hydrates of n-pentane and n-hexane with methane and 2,2-dimethylbutane, all of which form sH hydrates. The (13)C chemical shifts of the guest atoms in the hydrate are different from those in the free form, with some carbon atoms shifting specifically upfield. Such changes can be attributed to conformational changes upon fitting the large guest molecules in hydrate cages and/or interactions between the guests and the water molecules of the hydrate cages. In addition, powder X-ray diffraction measurements revealed that for the hexagonal unit cell, the lattice parameter along the a-axis changes with guest hydrate former molecule size and shape (in the range of 0.1 Å) but a much smaller change in the c-axis (in the range of 0.01 Å) is observed. The (13)C NMR chemical shifts for the pure hydrocarbons and all conformers were calculated using the gauge invariant atomic orbital method at the MP2/6-311+G(2d,p) level of theory to quantify the variation of the chemical shifts with the dihedral angles of the guest molecules. Calculated and measured chemical shifts are compared to determine the relative contribution of changes in the conformation and guest-water interactions to the change in chemical shift of the guest upon clathrate hydrate formation. Understanding factors that affect experimental chemical shifts for the enclathrated hydrocarbons will help in assigning spectra for complex hydrates recovered from natural sites. PMID:21329330

  20. Growth of Rhodococcus sp. strain BCP1 on gaseous n-alkanes: new metabolic insights and transcriptional analysis of two soluble di-iron monooxygenase genes

    PubMed Central

    Cappelletti, Martina; Presentato, Alessandro; Milazzo, Giorgio; Turner, Raymond J.; Fedi, Stefano; Frascari, Dario; Zannoni, Davide

    2015-01-01

    Rhodococcus sp. strain BCP1 was initially isolated for its ability to grow on gaseous n-alkanes, which act as inducers for the co-metabolic degradation of low-chlorinated compounds. Here, both molecular and metabolic features of BCP1 cells grown on gaseous and short-chain n-alkanes (up to n-heptane) were examined in detail. We show that propane metabolism generated terminal and sub-terminal oxidation products such as 1- and 2-propanol, whereas 1-butanol was the only terminal oxidation product detected from n-butane metabolism. Two gene clusters, prmABCD and smoABCD—coding for Soluble Di-Iron Monooxgenases (SDIMOs) involved in gaseous n-alkanes oxidation—were detected in the BCP1 genome. By means of Reverse Transcriptase-quantitative PCR (RT-qPCR) analysis, a set of substrates inducing the expression of the sdimo genes in BCP1 were assessed as well as their transcriptional repression in the presence of sugars, organic acids, or during the cell growth on rich medium (Luria–Bertani broth). The transcriptional start sites of both the sdimo gene clusters were identified by means of primer extension experiments. Finally, proteomic studies revealed changes in the protein pattern induced by growth on gaseous- (n-butane) and/or liquid (n-hexane) short-chain n-alkanes as compared to growth on succinate. Among the differently expressed protein spots, two chaperonins and an isocytrate lyase were identified along with oxidoreductases involved in oxidation reactions downstream of the initial monooxygenase reaction step. PMID:26029173

  1. Selective hydroxylation of alkanes by an extracellular fungal peroxygenase

    PubMed Central

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

    2013-01-01

    Fungal peroxygenases are novel extracellular heme-thiolate biocatalysts that are capable of catalyzing the selective monooxygenation of diverse organic compounds, using only H2O2 as a cosubstrate. Little is known about the physiological role or the catalytic mechanism of these enzymes. We have found that the peroxygenase secreted by Agrocybe aegerita catalyzes the H2O2-dependent hydroxylation of linear alkanes at the 2-position and 3-position with high efficiency, as well as the regioselective monooxygenation of branched and cyclic alkanes. Experiments with n-heptane and n-octane showed that the hydroxylation proceeded with complete stereoselectivity for the (R)-enantiomer of the corresponding 3-alcohol. Investigations with a number of model substrates provided information about the route of alkane hydroxylation: (a) the hydroxylation of cyclohexane mediated by H218O2 resulted in complete incorporation of 18O into the hydroxyl group of the product cyclohexanol; (b) the hydroxylation of n-hexane-1,1,1,2,2,3,3-D7 showed a large intramolecular deuterium isotope effect [(kH/kD)obs] of 16.0 ± 1.0 for 2-hexanol and 8.9 ± 0.9 for 3-hexanol; and (c) the hydroxylation of the radical clock norcarane led to an estimated radical lifetime of 9.4 ps and an oxygen rebound rate of 1.06 × 1011 s?1. These results point to a hydrogen abstraction and oxygen rebound mechanism for alkane hydroxylation. The peroxygenase appeared to lack activity on long-chain alkanes (> C16) and highly branched alkanes (e.g. tetramethylpentane), but otherwise exhibited a broad substrate range. It may accordingly have a role in the bioconversion of natural and anthropogenic alkane-containing structures (including alkyl chains of complex biomaterials) in soils, plant litter, and wood. PMID:21812933

  2. Excited state proton transfer reaction of two new intramolecularly hydrogen bonded Schiff bases at room temperature and 77K

    NASA Astrophysics Data System (ADS)

    Koll, A.; Filarowski, A.; Fitzmaurice, D.; Waghorne, E.; Mandal, A.; Mukherjee, S.

    2002-01-01

    Two new orthohydroxy Schiff bases, 7-phenylsalicylidene benzylamine (PSBA) and 7-ethylsalicylideneaniline (ESA) have been synthesized. The excited state intramolecular proton transfer (ESIPT) and the structure of PSBA and ESA in its crystalline form and in the solvents n-hexane, n-heptane and 1,4-dioxane have been investigated by means of absorption, emission and nanosecond spectroscopy at room temperature and 77K. One ground state species has been detected both in neutral and basic solutions of both PSBA and ESA: the cis-enol form with an intramolecular hydrogen bond. The ESIPT and formation of keto tautomer are evidenced by a large Stokes shifted emission (˜12?000 cm -1) at room temperature only in the case of ESA. On the other hand the keto tautomer is the predominant species at 77K in a solid matrix and as a solid sample at room temperature both in the case of ESA and PSBA. In the case of both ESA and PSBA the more intense, higher energy emission is due to the species which has not undergone ESIPT and attributed mainly due to cis-enol form. The trans-enol form is also observed by changing the excitation wavelength. Both the compounds are found to undergo a structural change to a zwitterionic and intermolecular hydrogen bonded form in the presence of a strong base like triethylamine. From the nanosecond measurements and quantum yield of fluorescence we have estimated the decay rates of proton transfer reaction in the case of PSBA. Our theoretical calculation at the AM1 level of approximation shows that the ground singlet state has a rather large activation barrier both in the case of PSBA and ESA. The barrier height is much lower on the corresponding excited singlet surface only in the case of ESA. The process is predicted to be endothermic in the ground state and exothermic in the excited singlet state.

  3. Phase equilibria study of the binary systems (N-hexylisoquinolinium thiocyanate ionic liquid + organic solvent or water).

    PubMed

    Królikowska, Marta; Karpi?ska, Monika; Zawadzki, Maciej

    2012-04-12

    Liquid-liquid phase equilibria (LLE) of binary mixtures containing a room-temperature ionic liquid N-hexylisoquinolinium thiocyanate, [HiQuin][SCN] with an aliphatic hydrocarbon (n-hexane, n-heptane), aromatic hydrocarbon (benzene, toluene, ethylbenzene, n-propylbenzene), cyclohexane, thiophene, water, and 1-alcohol (1-ethanol, 1-butanol, 1-hexanol, 1-octanol, 1-decanol) have been determined using a dynamic method from room temperature to the boiling-point of the solvent at ambient pressure. N-hexylisoquinolinium thiocyanate, [HiQuin][SCN] has been synthesized from N-hexyl-isoquinolinium bromide as a substrate. Specific basic characterization of the new compound including NMR spectra, elementary analysis, and water content have been done. The density and viscosity of pure ionic liquid were determined over a wide temperature range from 298.15 to 348.15 K. The mutual immiscibility with an upper critical solution temperature (UCST) for the binary systems {IL + aliphatic hydrocarbon, cyclohexane, or water} was detected. In the systems of {IL + aromatic hydrocarbon or thiophene} an immiscibility gap with a lower critical solution temperature (LCST) was observed. Complete miscibility in the liquid phase, over a whole range of ionic liquid mole fraction, was observed for the binary mixtures containing IL and an 1-alcohol. For the tested binary systems with immiscibility gap {IL + aliphatic hydrocarbon, aromatic hydrocarbon, cyclohexane, thiophene, or water}, the parameters of the LLE correlation have been derived using the NRTL equation. The basic thermal properties of the pure IL, that is, the glass-transition temperature as well as the heat capacity at the glass-transition temperature, have been measured using a differential scanning microcalorimetry technique (DSC). Decomposition of the IL was detected by simultaneous thermogravimetric/differential thermal analysis (TG/DTA) experiments. PMID:22424076

  4. Selective hydroxylation of alkanes by an extracellular fungal peroxygenase.

    PubMed

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

    2011-10-01

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

  5. Simultaneous indoor and outdoor on-line hourly monitoring of atmospheric volatile organic compounds in an urban building. The role of inside and outside sources.

    PubMed

    de Blas, Maite; Navazo, Marino; Alonso, Lucio; Durana, Nieves; Gomez, Maria Carmen; Iza, Jon

    2012-06-01

    Indoor air quality (IAQ) has become a very important issue in recent years. As in developed countries people spend more than 90% of their time indoors, besides outdoor pollution assessment, the indoor one is also required. IAQ is not only affected by indoor sources linked to indoor activities, outdoor sources such as road or street traffic and industrial and commercial activities have their role too. Volatile organic compounds (VOCs) frequently show higher indoor mixing ratios with respect to the outdoor ones, and monitoring is required to report their indoor mixing ratios. Many studies have reported average indoor VOCs' mixing ratios in different environments, but their temporal variability has not been well documented. The main objective of this work was to simultaneously measure VOCs' indoor and outdoor mixing ratios with high time-resolution in order to assess the effect of sources inside and outside the building upon indoor mixing ratios of individual VOCs. Simultaneous hourly, continuous, and on-line measurements of C(2)-C(11) VOCs were performed inside and outside the School of Engineering of Bilbao (ETSI) building, located in the city center of Bilbao, an urban area in Northern Spain. The analysis of simultaneous data allowed the classification of VOCs based on their main sources. Some VOCs were mainly emitted by indoor sources (1-pentene, 2-methylpentane, n-hexane, methylcyclopentane, benzene, 1-heptene+2,2,4-trimethylbenzene, and tetrachloroethylene) or by outdoor sources (n-heptane, C(8) alkanes except trimethylpentanes and C(9) aromatics). Other VOCs, such as toluene, were emitted by both indoor and outdoor sources. The isoprene indoor pattern indicated that its main indoor source could be the air exhaled by people occupying the building. Some halocarbons, such as trichloroethylene, tetrachloroethylene, and carbon tetrachloride may be generated from the use inside the building of chlorine bleach containing products. PMID:22542255

  6. Switching from photochemical to photothermal mechanism in laser ablation of benzene solutions

    NASA Astrophysics Data System (ADS)

    Hatanaka, Koji; Kawao, Mitsushi; Tsuboi, Yasuyuki; Fukumura, Hiroshi; Masuhara, Hiroshi

    1997-12-01

    Nanosecond KrF excimer laser ablation of benzyl chloride, benzyl alcohol, toluene, ethylbenzene, and n-propylbenzene diluted in n-hexane, n-heptane, dichloromethane, and 1,2-dichloroethane was investigated by time-resolved photographic, photoacoustic, and absorbance measurements. Ablation threshold values, Fth, for high concentration solutions (?=250 cm-1, 0.6-1 M) were confirmed to be correlated to photochemical reactivity (?-bond cleavage) of the solute molecules, whereas no distinct relation between Fth and boiling point of solvents was observed. Time-resolved absorbance at the laser wavelength was almost constant during the excitation pulse, which means that the main light-absorbing molecules were fixed to the ground-state solutes. It is considered that this type of ablation is initiated by the photochemical fragmentation. On the contrary, Fth observed in relatively low concentration solutions (?=25 cm-1, 0.06-0.1 M) were about twice higher than those for the high concentration solutions, and had no direct correlation with the photochemical reactivity of the solute molecules. The time-resolved absorbance increased during the excitation pulse, and was ascribed to the fact that benzyl radicals produced by the photodissociation of solute molecules absorbed the excitation photons and converted them into heat through "a cyclic multiphotonic absorption process." Furthermore, morphological aspects observed in nanosecond photography exhibited appreciable differences by varying the solute concentrations. These results clearly mean a concentration-dependent ablation mechanism; the ablation mechanism of the benzene derivative solutions switches from photochemical to photothermal as the solute concentration decreases.

  7. Environmental Technology Vol. 32, No. 6, April 2011, 617623

    E-print Network

    ; air pollution control; toluene; n-hexane; VOC mixtures Introduction Volatile organic compounds (VOCs treatment of mixtures of toluene and n-hexane vapours in a hollow fibre membrane bioreactor Kang Zhaoa, this study demonstrates that mixtures of toluene and n-hexane vapours can be effectively removed in hollow

  8. Fischer-Tropsch synthesis in supercritical reaction media. [Quarterly] progress report, July 1, 1993--September 30, 1993

    SciTech Connect

    Subramaniam, B.

    1993-10-01

    Figure 1 shows the physical appearance of the reactor and analytical units. The feed preparation section consists of a mass flow controller for syngas introduction, the BPLC pump for n-hexane introduction, preheaters, check valves, static mixer, and safety head has been completed. The stainless steel reactor was fabricated and was alonized to passivate the stainless steel surface. The fluidized sand bath surrounding the reactor was fabricated in house. Aluminum oxide (120 mesh) will be used as the fluidized medium. Stepping-motor-driven micrometering (Autoclave{reg_sign}) valves have been installed for pressure control of the reactor and of the syngas feed stream. The sample transfer lines connected to the gas sampling valves in the GC will be routed inside the valve oven and out through the front top of the GC, where they will be connected with the heated sample transfer lines from the reactor. The sample outlet line will be routed through a cold trap operated at 20{degrees}C or lower and the gases from the cold trap will be exhausted to the roof vent. The reactor unit is versatile and permits us to investigate the effect(s) of any of the following variables on syngas conversion, selectivity and reaction rate maintenance: (1) pressure (25--70) bars, (2) syngas flowrate (30--150) cc/min/g{center_dot}cat, (3) syngas ratio (H{sub 2}/CO of 0.5, 1.0 or 2.0) (4) ratio of syngas to reaction media (0.2--5.0), (5) catalyst type (Fe or Co), (6) direction of cocurrent flow (upflow or downflow), (7) cosolvent effects (such as n-pentane), and (8) sulfur content (1--50 mg{center_dot}/g{center_dot}Fe). Based on a literature review (Pennline et al., 1987; Baltrus et al., 1989; Bukur et al., 1990), the pretreatment of Fe catalysts will be performed with flowing CO at low pressure ({approximately}1 atm) and high temperatures ({approximately}280{degrees}C).

  9. Stereospecific determination of amisulpride, a new benzamide derivative, in human plasma and urine by automated solid-phase extraction and liquid chromatography on a chiral column. application to pharmacokinetics.

    PubMed

    Ascalone, V; Ripamonti, M; Malavasi, B

    1996-02-01

    Amisulpride, a drug belonging to the benzamide series, demonstrates antischizophrenic and antidepressant (antidysthymic) properties in man. For the pharmacokinetic studies of the racemic drug in man, a method of determination based on solid-phase extraction (SPE) from plasma and HPLC on a stereoselective column was developed. For this aim, one millilitre of plasma, after the addition of the internal standard, tiapride or metoclopramide, is diluted with a borate buffer at pH 9, then automatically loaded onto a SPE C18 100-mg column. The column is washed with different solvents, then eluted with 0.5 ml of methanol. After evaporation of the eluted fraction, the residue is reconstituted in 0.25 ml of eluent mixture. An aliquot is injected onto the HPLC column, a Chiralpak AS, equilibrated with an eluent mixture constituted by n-hexane-ethanol, (67:33, v/v) containing 0.2% (v/v) of diethylamine (DEA) or n-heptane-ethanol, (70:29.8, v/v) containing 0.2% of DEA and connected to a UV detector set at 280 nm or to a fluorimetric detector set at lambda ex = 280 nm and lambda cm = 370 nm. The limit of quantitation (LOQ) in human plasma is 2.5 ng ml-1 for both S-(-)- and R-(+)-amisulpride isomers with both detection methods. The method has been demonstrated to be linear in the range 2.5-320 ng ml-1 for both R-(+)- and S-(-)-amisulpride in human plasma with both UV and fluorescence detection. Absolute recovery of S-(-)- and R-(+)-amisulpride enantiomers from human plasma, as well as selectivity, precision and accuracy have been demonstrated to be satisfactory for pharmacokinetics in man and equivalent for both the proposed methods that have been cross-validated on real dosed human plasma samples. The methods have been used for clinical pharmacokinetic studies allowing pharmacokinetic parameters for amisulpride enantiomers in agreement with those obtained for the racemate to be obtained. After dilution with water, urinary samples from subjects treated with amisulpride racemate can be analysed according to the method used for plasma. PMID:8852049

  10. Development and implementation of a stereoselective normal-phase liquid chromatography-tandem mass spectrometry method for the determination of intrinsic metabolic clearance in human liver microsomes.

    PubMed

    Zhang, Yingru; Caporuscio, Christian; Dai, Jun; Witkusa, Michael; Rose, Anne; Santella, Joseph; D'Arienzo, Celia; Wang-Iverson, David B; Tymiak, Adrienne A

    2008-11-01

    The stereoselective determination of stereoisomers in biological samples provides vital information on stereospecific metabolism and pharmacokinetic profiles of the drugs. Despite the unique advantage and the great success of normal-phase (NP) HPLC for the separations of drug stereoisomers using polysaccharide-type chiral stationary phases (CSPs), the technique is rarely applied to quantitative HPLC-MS-MS bioanalysis. This is, at least in part, due to the incompatibility between the usual mobile phase (n-hexane or n-heptane) in normal-phase HPLC and the MS ionization sources which poses a potential detonation hazard. An environmentally friendly and nonflammable alternative solvent, ethoxynonafluorobutane (ENFB), was reported previously to potentially provide an ideal solution for combining the powers of stereoselective NP chromatographic separation and MS-MS detection. In this study, a stereoselective NP-HPLC-MS-MS method was developed using ENFB to quantify a pair of Bristol Myers Squibb (BMS) proprietary drug stereoisomers and their ketone metabolite for an in vitro study, which demonstrated, for the first time, the practical applicability and utility of ENFB for bioanalysis in pharmaceutical industry. The effects of different organic modifiers and temperature, as well as the comparison between ENFB and the usual solvent, heptane, for the separation, are discussed. The resolution of the stereoisomers was achieved using 63% of 3:1 mixture of ethanol and methanol with 37% ENFB on a Chiralpak AD-H column at 50 degrees C. High sensitivity was obtained using the MS-MS detection in the positive ion atmospheric pressure chemical ionization (APCI) mode. The lower limit of quantitation (LLOQ) for the first stereoisomer and the ketone metabolite was 5 ng/mL, and was 10 ng/mL for the second isomer in the human liver microsome-potassium phosphate buffer matrix. The linear dynamic range of 5-1000 ng/mL for both isomers and 10-1000 ng/mL for the metabolite were demonstrated with R2 > or =0.997. The precision of the analysis was <5% R.S.D. at or above the nominal concentration of 80 ng/mL, and <20% R.S.D. at 8 ng/mL. The mean bias was less than 15%. Extraction recovery and acceptable matrix interference were demonstrated using one isomer and the ketone, and better than 75% recovery and less than 25% ion suppression or interference were found. The method was successfully implemented for an in vitro intrinsic metabolic clearance study. PMID:18722827

  11. Enhancing chemical identification efficiency by SAW sensor transients through a data enrichment and information fusion strategy—a simulation study

    NASA Astrophysics Data System (ADS)

    Singh, Prashant; Yadava, R. D. S.

    2013-05-01

    The paper proposes a new approach for improving the odor recognition efficiency of a surface acoustic wave (SAW) transient sensor system based on a single polymer coating. The vapor identity information is hidden in transient response shapes through dependences on specific vapor solvation and diffusion parameters in the polymer coating. The variations in the vapor exposure and purge durations and the sensor operating frequency have been used to create diversity in transient shapes via termination of the vapor-polymer equilibration process up to different stages. The transient signals were analyzed by the discrete wavelet transform using Daubechies-4 mother wavelet basis. The wavelet approximation coefficients were then processed by principal component analysis for creating feature space. The set of principal components define the vapor identity information. In an attempt to enhance vapor class separability we analyze two types of information fusion methods. In one, the sensor operation frequency is fixed and the sensing and purge durations are varied, and in the second, the sensing and purge durations are fixed and the sensor operating frequency is varied. The fusion is achieved by concatenation of discrete wavelet coefficients corresponding to various transients prior to the principal component analysis. The simulation experiments with polyisobutylene SAW sensor coating for operation frequencies over [55-160] MHz and sensing durations over [5-60] s were analyzed. The target vapors are seven volatile organics: chloroform, chlorobenzene, o-dichlorobenzene, n-heptane, toluene, n-hexane and n-octane whose concentrations were varied over [10-100] ppm. The simulation data were generated using a SAW sensor transient response model that incorporates the viscoelastic effects due to polymer coating and an additive noise source in the output. The analysis reveals that: (i) in single transient analysis the class separability increases with sensing duration for a given frequency of operation, and also with frequency for a given sensing duration, and (ii) the information fusion based on both the multiple sensing cycles and the multiple sensing frequencies enhances the class separability by nearly an order of magnitude.

  12. Cytotoxic activity of plants of family zygophyllaceae and euphorbiaceae.

    PubMed

    Dastagir, Ghulam; Hussain, Farrukh

    2014-07-01

    The methanolic and n-hexane extracts of studied plants showed significant toxicity to brine shrimps. The methanolic extract of Fagonia cretica had highest LD50 (117.72) value, while Peganum harmala showed low LD50 value (41.70) compared to n-hexane extract. The methanolic and n-hexane extracts of Tribulus terrestris showed similar LD50 values. The methanolic extract of Chrozophora tinctoria showed low LD50 value than the n-hexane extract. The methanolic extract of Ricinus communis showed highest LD50 value while the n-hexane extract showed lowest LD50 value. The LD50 value less than 100 was obtained for n-hexane extracts of Fagonia cretica, Peganum harmala and Ricinus communis. The n-hexane extracts of these plants also showed the highest toxicity as compare to methanolic extracts. The chemical constituents detected in the present investigation might be responsible for cytotoxic activity. PMID:25015443

  13. Immiscible Systems

    ERIC Educational Resources Information Center

    Eckelmann, Jens; Luning, Ulrich

    2013-01-01

    layers of liquids. The setup of both demonstrations is such that one homogeneous layer in a multiphasic mixture separates into two new layers upon shaking. The solvents used are methanol, toluene, petroleum ether or "n"-pentane, silicone oil, perfluoroheptanes,…

  14. Solvation dynamics of 4-(dicyanomethylene)-2-methyl-6-( p-dimethylaminostyryl)-4H-pyran (DCM) in a microemulsion

    NASA Astrophysics Data System (ADS)

    Pal, Samir Kumar; Mandal, Debabrata; Sukul, Dipankar; Bhattacharyya, Kankan

    1999-10-01

    The photophysical process of the laser dye 4-(dicyanomethylene)-2-methyl-6-( p-dimethylaminostyryl)-4H-pyran (DCM) is studied in aerosol-OT (AOT) microemulsions in n-heptane using picosecond spectroscopy. When AOT and water are added to a solution of DCM in n-heptane, some of the DCM molecules migrate from bulk n-heptane to the water pool. The absorption and emission peaks of the DCM molecules in the polar water pool are markedly red shifted from those in the bulk n-heptane and the emission intensity in the water pool is nearly 40 times higher. Dual emission is not observed in the microemulsions. DCM exhibits slow solvation dynamics in the water pool with an average solvation time of 1.23 ns.

  15. 21 CFR 177.1655 - Polysulfone resins.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... extracted at reflux temperatures for 6 hours with the solvents—distilled water, 50 percent (by volume) ethyl alcohol in distilled water, 3 percent acetic acid in distilled water, and n-heptane, yield...

  16. Process Simulation and Evaluation of Alternative Solvents for Jatropha Curcas L. Seed Oil Extraction in Biodiesel Production 

    E-print Network

    Chiou, Ming-Hao

    2012-10-19

    -case flowsheet is synthesized for oil extraction. Then, the base-case extraction process and each solvent Fire and Explosion Index (F & EI) and the Solvent Safety Index (SSI). Eight solvents, including n-heptane, toluene, xylene, dichloromethane, chloroform, 1...

  17. Understanding Loss Mechanisms and Efficiency Improvement Options for HCCI Engines Using Detailed Exergy Analysis

    E-print Network

    Saxena, Samveg

    2013-01-01

    was collected at the Combustion Analysis Laboratory at theAnalysis of n- heptane and Natural Gas blends Combustion inanalysis of 72 different cycle simulations, each representing a different intake pressure and combustion

  18. Research on Volatile Organic Compounds in the Mexico City Metropolitan Area (MCMA) in two campaigns collected in the Winter-2011 and Spring-2012

    NASA Astrophysics Data System (ADS)

    Magaña, M.; González-Vargas, S.; Blanco, S.; Watanabe, T.; Maeda, T.; Cardenas, B.

    2013-05-01

    Because of the importance of information on the concentration and speciation of Volatile Organic Compounds (VOC) in the atmosphere for the development of regulatory programs or emission control, is necessary to determine the type and the concentrations of reactive and toxic VOC in atmospheric air. The aim of this study is to determine the speciation and quantification of VOC in the atmospheric air of the Mexico City Metropolitan Area (MCMA), from samples obtained in November-December 2011 (cold-dry) and March-April (warm-dry). This study presents the results of characterization of VOC in ambient air in the MCMA conducted during 2011-2012. Sampling of VOC was done in two sampling campaigns: from November 17th to December 11th, 2011, and March 1st to April 6th, 2012 through collection of ambient air each six days in six liters stainless steel SUMMA canisters of 24 hours integrated samples, in three sites (Merced: commercial area with vehicular sources, Pedregal: residential area with vehicular sources and San Agustin: industrial sources with heavy traffic), in the MCMA. The analysis of samples was carried out with two chromatographic systems: 1) method equivalent to the EPA's Method TO-14, and 2) GC/MSD coupled to a preconcentrator ENTECH, for the analysis of the compounds listed in EPA method TO15. It was investigated the concentration of 111 volatile organic compounds, (ozone precursors and toxic compounds). It was found that concentrations of 23 species, constitute 80% of the total VOC concentration tested: ethane, propane, isobutane, n-butane, n-pentane, n-hexane, isopentane, methylcyclopentane, ethylene, propylene, acetylene, benzene, toluene, ethylbenzene, m/p-xylene, o-xylene, 1,2,4-trimethylbenzene, ethyl and isopropyl alcohols, acetone, 2-butanone, MTBE and ethyl acetate. Both in 2011 and 2012, the highest concentrations measured in the three sites were for compounds associated with the combustion of LPG gas: propane, n-butane. The highest concentrations of 25.2±14.5 ppbV and 16.6±9 ppbV for butane and propane respectively, was achieved in Merced in 2011 and 14.7±3.5 ppbV and 28.4±6.7 ppbV for the same compounds, in San Agustin in 2012). In the case of vehicular emissions, in both campaigns, 2011 and 2012, Merced showed the highest levels: 12.3±4.8 ppbV, 2.7±1.1 ppbV and 4.3±3.3 ppbV for toluene, benzene and MTBE respectively in 2011 and 9.48±6.5 ppbV, 1.5±0.9 ppbV and 2.4±1.0 ppbV for the same compounds in 2012. The compounds which comes from industrial emissions, have the lowest average concentrations in all stations. The VOCs measurement in atmospheric air, allowed determinate that the main source of VOC in the three studied sites of the MCMA are emissions of LPG gas and vehicular emissions. The highest concentrations were found during the cold-dry period in 2011. These data are consistent with continuous measurements determined in the southeastern MCMA during 2000-2007.

  19. DOI: 10.1002/chem.200501053 Micelle-to-Vesicle Transition Induced by Organic Additives in Catanionic

    E-print Network

    Huang, Jianbin

    in a number of practical applica- tions[2] and of fundamental interest as well.[3] For catanionic surfactant, n-hexane, n-octane, and n-dodecane) and polar organ- ic additives, such as n-octanol and n hydrocarbons (n-bu- tylbenzene, n-hexane, n-octane, and n- dodecane) to the catanionic surfactant system n

  20. Electron Transport in Paracoccus Halodenitrificans and the Role of Ubiquinone

    NASA Technical Reports Server (NTRS)

    Hochstein, L. I.; Cronin, S. E.

    1983-01-01

    The membrane-bound NADH oxidase of Paracoccus halodenitrificans was inhibited by dicoumarol, 2-n-heptyl-4-hydroxyquinoline-N-oxide (HQNO), and exposure to ultraviolet light (at 366 nm). When the membranes were extracted with n-pentane, NADH oxidase activity was lost. Partial restoration was achieved by adding the ubiquinone fraction extracted from the membranes. Succinate oxidation was not inhibited by dicoumarol or HQNO but was affected by ultraviolet irradiation or n-pentane extraction. However, the addition of the ubiquinone fraction to the n-pentane-extracted membranes did not restore enzyme activity. These observations suggested the reducing equivalents from succinate entered the respiratory chain on the oxygen side of the HQNO-sensitive site and probably did not proceed through a quinone.

  1. Understanding nanofluid stability through molecular simulation

    SciTech Connect

    Dang, Liem X.; Annapureddy, Harsha V.; Sun, Xiuquan; Thallapally, Praveen K.; McGrail, B. Peter

    2012-11-01

    We performed molecular dynamics simulations to study solvation of a nanoparticle and nanoparticle-nanoparticle interactions in an n-hexane solution. Structural signatures are barely observed between the nanoparticle and n-hexane molecules because of weak binding and steric effects. The dynamic properties of the n-hexane molecule, on the other hand, are significantly influenced by the solvated nanoparticle. The diffusion of n-hexane molecules inside the nanoparticle is significantly decreased mainly because of the loss of dimensions of translation. Because one translational degree of freedom is lost by colliding with the wall of nanoparticle, the n-hexane molecules outside the nanoparticle diffuse 30% slower than the molecules in pure solution. The computed free energy profiles illustrate that the arrangement of the nanoparticles in bulk n-hexane solution are dependent on the orientation and functional group. We found that the n-hexane solvent exerts some effects on the interactions between the solvated nanoparticles. This work was supported by the US Department of Energy, Office of Basic Energy Sciences, Division of Chemical Sciences, Geosciences, and Biosciences and by the Office of Energy Efficiency and Renewable Energy, Geothermal Technologies Program. Pacific Northwest National Laboratory (PNNL) is a multiprogram national laboratory operated for DOE by Battelle.

  2. Modeling the Auto-Ignition of Biodiesel Blends with a Multi-Step Model

    SciTech Connect

    Toulson, Dr. Elisa; Allen, Casey M; Miller, Dennis J; McFarlane, Joanna; Schock, Harold; Lee, Tonghun

    2011-01-01

    There is growing interest in using biodiesel in place of or in blends with petrodiesel in diesel engines; however, biodiesel oxidation chemistry is complicated to directly model and existing surrogate kinetic models are very large, making them computationally expensive. The present study describes a method for predicting the ignition behavior of blends of n-heptane and methyl butanoate, fuels whose blends have been used in the past as a surrogate for biodiesel. The autoignition is predicted using a multistep (8-step) model in order to reduce computational time and make this a viable tool for implementation into engine simulation codes. A detailed reaction mechanism for n-heptane-methyl butanoate blends was used as a basis for validating the multistep model results. The ignition delay trends predicted by the multistep model for the n-heptane-methyl butanoate blends matched well with that of the detailed CHEMKIN model for the majority of conditions tested.

  3. Extraction-atomic absorption determination of copper in river water with preliminary concentration by capric acid and benzylamine

    SciTech Connect

    Onishchenko, T.A.

    1986-02-01

    A study has been made of the extraction of copper (II) by 1 M solutions of capric acid in toluene and n-heptane, and also in n-heptane in the presence of pyridine, benzylamine, or 1,10-phenanthroline. The compositions of the copper compounds with capric acid and amines that are extracted were established by photometric and polarographic methods. An extractionatomic absorption method is proposed for determining copper in river water, with a detection limit of 0.3 mu g/liter.

  4. Investigations on radical formation and inactivation of suspended trypsin after gamma-irradiation.

    PubMed

    Nemec, H W; Mönig, H

    1977-07-29

    Crystalline trypsin was irradiated in oxygen-free suspension media of methanol, ethanol and n-heptane with 60Co-gamma-rays at 77 K or 273 K. Measurements with ESR and activity determinations revealed no influence of ethanol and n-heptane on the formation of free radicals and inactivation of trypsin. Especially, the results are independent on the polarity of the suspension media and correspond to an irradiation of trypsin in vacuum. On the other hand, methanol leads to a decay of radiation induced radicals and to an increased inactivation. The results are discussed in comparison to analogous experiments carried out with ultra-violet light. PMID:197563

  5. Multiphoton ionization and excitation spectroscopy of molecules in liquids. [Fluoranthene

    SciTech Connect

    Siomos, K.; Faidas, H.; Christophorou, L.G.

    1984-01-01

    The two-photon ionization and excitation spectra of fluoranthene in liquid n-pentane have been measured and together with laser power versus signal intensity measurements have been utilized to elucidate the multiphoton ionization mechanism for this and other molecules in liquids.

  6. Bilinear estimation of pollution source profiles in receptor models

    E-print Network

    Washington at Seattle, University of

    species in the emissions from the kth source, ik is the contribution from the kth source on the ith day for a refinery might look like Propane, 21%; n- Butane, 18%; i-Pentane, 17%; n-Pentane, 7%; 2-Methylpentane, 7

  7. Conservative and dissipative force field for simulation of coarse-grained alkane molecules: A bottom-up approach

    SciTech Connect

    Trément, Sébastien; Rousseau, Bernard; Schnell, Benoît; Petitjean, Laurent; Couty, Marc

    2014-04-07

    We apply operational procedures available in the literature to the construction of coarse-grained conservative and friction forces for use in dissipative particle dynamics (DPD) simulations. The full procedure rely on a bottom-up approach: large molecular dynamics trajectories of n-pentane and n-decane modeled with an anisotropic united atom model serve as input for the force field generation. As a consequence, the coarse-grained model is expected to reproduce at least semi-quantitatively structural and dynamical properties of the underlying atomistic model. Two different coarse-graining levels are studied, corresponding to five and ten carbon atoms per DPD bead. The influence of the coarse-graining level on the generated force fields contributions, namely, the conservative and the friction part, is discussed. It is shown that the coarse-grained model of n-pentane correctly reproduces self-diffusion and viscosity coefficients of real n-pentane, while the fully coarse-grained model for n-decane at ambient temperature over-predicts diffusion by a factor of 2. However, when the n-pentane coarse-grained model is used as a building block for larger molecule (e.g., n-decane as a two blobs model), a much better agreement with experimental data is obtained, suggesting that the force field constructed is transferable to large macro-molecular systems.

  8. Fluid transport properties by equilibrium molecular dynamics. II. Multicomponent systems

    E-print Network

    Dysthe, Dag Kristian

    and mixed with CO2 and N2 .21 The bulk of research articles in this field has been de- voted simulation results of N2 ­n-pentane agree with experiment with a maximum deviation of 36%, the greatest error and multicenter molecular models.8­16 d The study of transport properties of certain fluids and classes of fluids

  9. A predictive method for volatile organic compounds emission from soil: Evaporation and diffusion behavior investigation of a representative component of crude oil.

    PubMed

    Wang, Haijing; Fischer, Thomas; Wieprecht, Wolfgang; Möller, Detlev

    2015-10-15

    Pipelines are convenient, economical and widely used mode of transportation of crude oil. However, the inevitable or otherwise accidents during such transport of crude oil lead to large scale oil spills, which consequently result in both soil and air pollution. When such pollution occurs, crude oil VOC concentrations in air, soil pollution evaluation and VOC propagation in soil provide important evidence for airborne detection of oils spills. Therefore, several issues, including determination method for VOC, isotherm parameters of VOC sorption on soil surfaces, and VOC diffusion flux simulation, are significant. In our previous study, n-butane and n-pentane were proved to be the maximum VOCs in studied crude oils. Therefore, a predictive method using n-pentane as a representative component is proposed in this paper. Firstly, a headspace solid phase microextraction (SPME) method was developed for determination of n-pentane in non-equilibrium mass transfer conditions. Secondly, Brunauer-Emmett-Teller (BET) analysis with liquid nitrogen was carried out to predict isotherm parameters for n-pentane. Finally, two models were used to predict the emission process. Probably influenced by gas vapor density below and above the soil layer, the experimental data amounted to 74% of the deduced value from the simplified analytical model. However, the free diffusion model fitted well with the experimental results. PMID:26026407

  10. Stat 511 Exam 2 April 7, 2009

    E-print Network

    Vardeman, Stephen B.

    vapor pressure of the sample 10 ASTM 10% point volatility of the crude oil sample end point volatility-pentane to iso-pentane upon some partial pressures. For 1 2 3 gm of iso-pentance produced per hour per gm of catalyst hydrogen partial pressure n-pentane partial pressure iso-pentane partial pressure y rate x H x n

  11. Analytical Laboratory for Cottonseed Work 

    E-print Network

    Unknown

    2011-08-17

    The kinetics of enzyme-catalyzed esterification of triglycerides over immobilized lipase in n-hexane was investigated. The reaction kinetics were described in terms of a mechanism developed following the Langmuir-Hinshel ...

  12. Adsorption and desorption of binary mixtures of volatile organic contaminants on soil 

    E-print Network

    Guo, Yang

    1995-01-01

    The adsorption equilibria of four volatile organic compounds, n-hexane, toluene, methanol and chlorobenzene on Highbank #4471 soil were measured by a dynamic response technique based on frontal analysis chromatography. The ...

  13. Preparative isolation and purification of coumarins from Angelica dahurica (Fisch. ex Hoffn) Benth, et Hook. f (Chinese traditional medicinal herb) by high-speed counter-current chromatography.

    PubMed

    Liu, Renmin; Li, Aifeng; Sun, Ailing

    2004-10-15

    A preparative high-speed counter-current chromatography (HSCCC) method for isolation and purification of coumarins from Angelica dahurica (Fisch. ex Hoffin) Benth, et Hook. f(Baizhi in Chinese) was successfully established by using n-hexane-methanol-water as the two-phase solvent system in gradient elution mode. The upper phase of n-hexane-methanol-water (5:5:5, v/v) was used as the stationary phase of HSCCC. The mobile phase used in HSCCC was the lower phase of n-hexane-methanol-water (5:5:5, v/v) and n-hexane-methanol-water (5:7:3, v/v) that was changed in gradient. Three major components including imperatorin, isoimperatorin and oxypeucedanine were isolated, each at over 98% purity as determined by high-performance liquid chromatography (HPLC). The peak fractions of HSCCC were identified by 1H-NMR and 13C-NMR. PMID:15527142

  14. Modeling of the Cryogenic Liquid Pool Evaporation and the Effect of the Convective Heat Transfer from Atmosphere 

    E-print Network

    Nawaz, Waqas

    2014-04-25

    was validated against the experiments performed by Kawamura and Mackay. The experiments were conducted in Woodbridge Ontario using a number of chemicals, namely toluene, cyclohexane, n-hexane, methanol, pentane, dichloromethane and tri.... Experiment was performed with Toluene, cyclohexane, n-hexane, Evaporation Measuring Device Evaporation Pan Styrofoam 26 dichloromethane and tri-chloro-fluro-methane (freon-11). The chemical in the pan was allowed to evaporate till, either the level...

  15. LOW OZONE-DEPLETING HALOCARBONS AS TOTAL-FLOOD AGENTS: VOLUME 2. LABORATORY-SCALE FIRE SUPPRESSION AND EXPLOSION PREVENTION TESTING

    EPA Science Inventory

    The report gives results from (1) flame suppression testing of potential Halon-1301 (CF3Br) replacement chemicals in a laboratory cup burner using n-heptane fuel and (2) explosion prevention (inertion) testing in a small-scale explosion sphere using propane and methane as fuels. ...

  16. 21 CFR 177.1040 - Acrylonitrile/styrene copoly-mer.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... exposed to distilled water and 3 pct acetic acid for 10 d at 66 °C (150 °F)The extracted copolymer shall... 3 pct acetic acid for 10 d at 66 °C (150 °F) 1 Minimum number average molecular weight is 30,000. 1... Sieve No. 10 is extracted with 250 mil of deionized water or reagent grade n-heptane at...

  17. 21 CFR 177.1050 - Acrylonitrile/styrene copoly-mer modified with butadiene/styrene elastomer.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... copolymer is extracted with 250 milliliters of freshly distilled water at reflux temperature for 2 hours. (2... copol-ymer is extracted with 250 milliliters spectral grade n-heptane at reflux temperature for 2 hours... milliliters of 3 percent acetic acid in a Pyrex glass pressure bottle. (3) The pyrex glass pressure bottle...

  18. 40 CFR Appendix A to Part 439 - Tables

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ...Ethanol 1 Isopropanol 1 Methanol 1 Phenol Isobutyraldehyde 1 Aldehydes. n-Heptane...Isopropyl acetate n-Amyl acetate n-Butyl acetate Methyl formate Tetrahydrofuran...4-methyl-2-pentanone n-Amyl acetate n-Butyl acetate Ethyl acetate Medium...

  19. 21 CFR 177.1980 - Vinyl chloride-propylene copolymers.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... equivalent weight of chlorine divided by the chlorine content of the heptane extractable fraction.) (e) The....10 weight-percent when extracted with n-heptane at 150 °F for 2 hours. (ii) Total extractives do not exceed 0.03 weight-percent when extracted with water at 150 °F for 2 hours. (iii) Total...

  20. 21 CFR 177.1980 - Vinyl chloride-propylene copolymers.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    .... Note: The conversion factor, 84.5, is derived from the equivalent weight of chlorine divided by the... not exceed 0.10 weight-percent when extracted with n-heptane at 150 °F for 2 hours. (ii) Total extractives do not exceed 0.03 weight-percent when extracted with water at 150 °F for 2 hours. (iii)...

  1. 21 CFR 177.1980 - Vinyl chloride-propylene copolymers.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    .... Note: The conversion factor, 84.5, is derived from the equivalent weight of chlorine divided by the... not exceed 0.10 weight-percent when extracted with n-heptane at 150 °F for 2 hours. (ii) Total extractives do not exceed 0.03 weight-percent when extracted with water at 150 °F for 2 hours. (iii)...

  2. 21 CFR 177.1980 - Vinyl chloride-propylene copolymers.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    .... Note: The conversion factor, 84.5, is derived from the equivalent weight of chlorine divided by the... not exceed 0.10 weight-percent when extracted with n-heptane at 150 °F for 2 hours. (ii) Total extractives do not exceed 0.03 weight-percent when extracted with water at 150 °F for 2 hours. (iii)...

  3. 21 CFR 177.1980 - Vinyl chloride-propylene copolymers.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    .... Note: The conversion factor, 84.5, is derived from the equivalent weight of chlorine divided by the... not exceed 0.10 weight-percent when extracted with n-heptane at 150 °F for 2 hours. (ii) Total extractives do not exceed 0.03 weight-percent when extracted with water at 150 °F for 2 hours. (iii)...

  4. 21 CFR 177.1040 - Acrylonitrile/styrene copoly-mer.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... deionized water or reagent grade n-heptane at reflux temperature for 2 h.1 Minimum 10 pct solution viscosity... viscosity, titled: “Determination of Residual Acrylonitrile and Styrene Monomers-Gas Chromatographic... Copolymers,” and “Analytical Method for 10% Solution Viscosity of Tyril,” which are incorproated by...

  5. 40 CFR Appendix Xvii to Part 86 - Procedure for Determining Vehicle Emission Control Technology Category/Fuel Reactivity Adjustment...

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ...measured by the manufacturer and the maximum incremental...methanol 0.56 00064-17-5 ethanol 1.34 Light End and Mid-Range Hydrocarbons (Listed...trans-3-heptene 5.53 00142-82-5 n-heptane 0.81 02738-19-4...

  6. Low-temperature phosphorescence and ODMR study of 2,2'-bipyridine and Rh(bpy) 3+3

    NASA Astrophysics Data System (ADS)

    Suisalu, A. P.; Kamyshnyi, A. L.; Zakharov, V. N.; Aslanov, L. A.; Avarmaa, R. A.

    1987-03-01

    Phosphorescence and optically detected magnetic resonance (ODMR) spectra in zero field, as well as their kinetics, were measured for 2,2'-bipyridine in n-heptane and its rhodium complex in ethanol at T= 1.8 K. The triplet-state Sublevel scheme of both compounds is discussed.

  7. [Solubility of the sodium salt of novobiocin in ethyl alcohol mixtures with other solvents].

    PubMed

    Slavin, A A; Etingov, E D; Tomchina, L F; Brunshte?n, I Z

    1979-06-01

    Solubility of sodium novobiocin in binary mixtures of ethyl alcohol with ehtyl acetate, methylene chloride, diethyl ether, carbon tetrachloride or n-heptane was studied. Deviation in the sodium novobiocin solubility from the additivity was observed depending on the nature of the second component of the solvent mixture. PMID:453794

  8. 2007-01-0175 Development of an Experimental Database and Chemical

    E-print Network

    Pitsch, Heinz

    ratings, also find widespread use as convenient surrogates for variable octane number fuel. Ternary of a fully-blended fuel. The simplest surrogate fuels consist of single components, e.g., the use of iso-octane as a gasoline surrogate. Binary blends of n-heptane and iso- octane, the primary reference fuels for octane

  9. Twenty-Seventh Symposium (International) on Combustion/The Combustion Institute, 1998/pp. 20692076 PLANAR LASER-INDUCED FLUORESCENCE IMAGING OF CREVICE

    E-print Network

    Long, Marshall B.

    -induced fluorescence (PLIF) from iso-octane/n-heptane fuel blends doped with 3-pentanone. The fluorescence was imaged with lower octane ratings were shown to enhance flame penetration due to their increased reactivity source of crevice emissions, and a number of studies have been undertaken in an at- tempt to minimize

  10. This article was published in an Elsevier journal. The attached copy is furnished to the author for non-commercial research and

    E-print Network

    Skogestad, Sigurd

    components for use in high-performance gasoline fuels. ``Octane'' or, more precisely the octane number''. The most common measure of the octane number is the RON (research octane number). By definition iso-octane (2,2,4- trimethyl pentane) is given an octane number (RON) of 100 and n-heptane an octane number of 0

  11. 21 CFR 177.1820 - Styrene-maleic anhydride copolymers.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ...) Specifications: Styrene-maleic copolymers Molecular weight (minimum number average) Residual styrene monomer Residual maleic anhydride monomer Maximum extractable fraction in distilled water at specified temperatures, times, and particle size Maximum extractable fraction in n-heptane at specified temperatures, times,...

  12. 21 CFR 177.2470 - Polyoxymethylene copolymer.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... copolymer when extracted for 6 hours with distilled water at reflux temperature. (ii) Not to exceed 0.15 percent by weight of the copolymer when extracted for 6 hours with n-heptane at reflux temperature. (e... product of trioxane (cyclic trimer of formaldehyde) and a maximum of 5 percent by weight of...

  13. 21 CFR 177.1330 - Ionomeric resins.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... the time and temperatures as follows: Solvent Time Temperature n-Heptane 1 2 120 °F (49 °C). Water, 3... weight), prepared from glacial acetic acid diluted with demineralized (deionized), distilled water. (4... no more than 20 weight percent of polymer units derived from methacrylic acid, and the...

  14. 21 CFR 177.2470 - Polyoxymethylene copolymer.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... copolymer when extracted for 6 hours with distilled water at reflux temperature. (ii) Not to exceed 0.15 percent by weight of the copolymer when extracted for 6 hours with n-heptane at reflux temperature. (e... product of trioxane (cyclic trimer of formaldehyde) and a maximum of 5 percent by weight of...

  15. 21 CFR 177.2470 - Polyoxymethylene copolymer.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... copolymer when extracted for 6 hours with distilled water at reflux temperature. (ii) Not to exceed 0.15 percent by weight of the copolymer when extracted for 6 hours with n-heptane at reflux temperature. (e... product of trioxane (cyclic trimer of formaldehyde) and a maximum of 5 percent by weight of...

  16. 21 CFR 177.1556 - Polyaryletherketone resins.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... temperature for 2 hours with the following solvents: Distilled water, 50 percent (by volume) ethyl alcohol in distilled water, 3 percent acetic acid (by weight) in distilled water, and n-heptane. (d) In testing the... such a way that the finished resins have a minimum weight average molecular weight of 20,000 grams...

  17. 21 CFR 177.2470 - Polyoxymethylene copolymer.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... copolymer when extracted for 6 hours with distilled water at reflux temperature. (ii) Not to exceed 0.15 percent by weight of the copolymer when extracted for 6 hours with n-heptane at reflux temperature. (e... product of trioxane (cyclic trimer of formaldehyde) and a maximum of 5 percent by weight of...

  18. Computational Analysis of Thermo-Fluidic Characteristics of a Carbon Nano-Fin 

    E-print Network

    Singh, Navdeep

    2011-02-22

    nano fin in diff erent kinds of coolants. So in this work to elucidate the eff ect of the molecular composition and structures on the interfacial thermal resistance, water, ethyl alcohol, 1-hexene, n-heptane and its isomers and chains are considered...

  19. Using Nuclear Magnetic Resonance Spectroscopy for Measuring Ternary Phase Diagrams

    ERIC Educational Resources Information Center

    Woodworth, Jennifer K.; Terrance, Jacob C.; Hoffmann, Markus M.

    2006-01-01

    A laboratory experiment is presented for the upper-level undergraduate physical chemistry curriculum in which the ternary phase diagram of water, 1-propanol and n-heptane is measured using proton nuclear magnetic resonance (NMR) spectroscopy. The experiment builds upon basic concepts of NMR spectral analysis, typically taught in the undergraduate…

  20. Continuous and Batch Distillation in an Oldershaw Tray Column

    ERIC Educational Resources Information Center

    Silva, Carlos M.; Vaz, Raquel V.; Santiago, Ana S.; Lito, Patricia F.

    2011-01-01

    The importance of distillation in the separation field prompts the inclusion of distillation experiments in the chemical engineering curricula. This work describes the performance of an Oldershaw column in the rectification of a cyclohexane/n-heptane mixture. Total reflux distillation, continuous rectification under partial reflux, and batch…

  1. Numerical investigation of spontaneous flame propagation under RCCI conditions

    SciTech Connect

    Bhagatwala, Ankit V; Sankaran, Ramanan; Kokjohn, Sage; Chen, Jacqueline H

    2015-06-30

    This paper presents results from one and two-dimensional direct numerical simulations under Reactivity Controlled Compression Ignition (RCCI) conditions of a primary reference fuel (PRF) mixture consisting of n-heptane and iso-octane. RCCI uses in-cylinder blending of two fuels with different autoignition characteristics to control combustion phasing and the rate of heat release. These simulations employ an improved model of compression heating through mass source/sink terms developed in a previous work by Bhagatwala et al. (2014), which incorporates feedback from the flow to follow a predetermined experimental pressure trace. Two-dimensional simulations explored parametric variations with respect to temperature stratification, pressure profiles and n-heptane concentration. Furthermore, statistics derived from analysis of diffusion/reaction balances locally normal to the flame surface were used to elucidate combustion characteristics for the different cases. Both deflagration and spontaneous ignition fronts were observed to co-exist, however it was found that higher n-heptane concentration provided a greater degree of flame propagation, whereas lower n-heptane concentration (higher fraction of iso-octane) resulted in more spontaneous ignition fronts. A significant finding was that simulations initialized with a uniform initial temperature and a stratified n-heptane concentration field, resulted in a large fraction of combustion occurring through flame propagation. The proportion of spontaneous ignition fronts increased at higher pressures due to shorter ignition delay when other factors were held constant. For the same pressure and fuel concentration, the contribution of flame propagation to the overall combustion was found to depend on the level of thermal stratification, with higher initial temperature gradients resulting in more deflagration and lower gradients generating more ignition fronts. Statistics of ignition delay are computed to assess the Zel’dovich (1980) theory for the mode of combustion propagation based on ignition delay gradients.

  2. Numerical investigation of spontaneous flame propagation under RCCI conditions

    DOE PAGESBeta

    Bhagatwala, Ankit V; Sankaran, Ramanan; Kokjohn, Sage; Chen, Jacqueline H

    2015-06-30

    This paper presents results from one and two-dimensional direct numerical simulations under Reactivity Controlled Compression Ignition (RCCI) conditions of a primary reference fuel (PRF) mixture consisting of n-heptane and iso-octane. RCCI uses in-cylinder blending of two fuels with different autoignition characteristics to control combustion phasing and the rate of heat release. These simulations employ an improved model of compression heating through mass source/sink terms developed in a previous work by Bhagatwala et al. (2014), which incorporates feedback from the flow to follow a predetermined experimental pressure trace. Two-dimensional simulations explored parametric variations with respect to temperature stratification, pressure profiles andmore »n-heptane concentration. Furthermore, statistics derived from analysis of diffusion/reaction balances locally normal to the flame surface were used to elucidate combustion characteristics for the different cases. Both deflagration and spontaneous ignition fronts were observed to co-exist, however it was found that higher n-heptane concentration provided a greater degree of flame propagation, whereas lower n-heptane concentration (higher fraction of iso-octane) resulted in more spontaneous ignition fronts. A significant finding was that simulations initialized with a uniform initial temperature and a stratified n-heptane concentration field, resulted in a large fraction of combustion occurring through flame propagation. The proportion of spontaneous ignition fronts increased at higher pressures due to shorter ignition delay when other factors were held constant. For the same pressure and fuel concentration, the contribution of flame propagation to the overall combustion was found to depend on the level of thermal stratification, with higher initial temperature gradients resulting in more deflagration and lower gradients generating more ignition fronts. Statistics of ignition delay are computed to assess the Zel’dovich (1980) theory for the mode of combustion propagation based on ignition delay gradients.« less

  3. Simulating vapor-liquid nucleation of n-alkanes

    NASA Astrophysics Data System (ADS)

    Chen, Bin; Siepmann, J. Ilja; Oh, Kwang J.; Klein, Michael L.

    2002-03-01

    A combination of the aggregation-volume-bias Monte Carlo algorithm, the configurational-bias Monte Carlo algorithm, and the umbrella sampling technique was applied to investigate homogeneous vapor-liquid nucleation in ethane, n-butane, and n-heptane. The simple transferable potentials for phase equilibria-united atom (TraPPE-UA) force field was used in this investigation. It was found that for the n-heptane case, the TraPPE-UA force field predicted a nucleation rate that is about three to four orders of magnitude higher than that measured by an upward thermal diffusion cloud chamber experiment. Comparison of the simulation results to the classical nucleation theory (CNT) shows that CNT consistently overestimates the barrier heights for all chain lengths investigated. The offset on the barrier heights was found nearly independent of the supersaturation for both ethane and n-butane, similar to a Lennard-Jones system previously studied. This also directly leads to a good agreement on the cluster sizes between the simulation and the CNT calculated from the nucleation theorem. For n-heptane, however, the offset was found to depend on the supersaturation. It appears that CNT predicts a slightly weaker dependence of the nucleation rate on supersaturation, which agrees with both density functional calculations and the experiments. Structural analysis demonstrates that the orientational order near the surface differs significantly between the critical nucleus and the bulk planar liquid-vapor interface for n-heptane systems, whereas the density in the interior of the critical nucleus is in good agreement with the bulk liquid density. The different surface ordering offers a microscopic explanation for the differences observed for n-heptane between the CNT on one side and experimental observations and simulations on the other side.

  4. HCCI experiments with toluene reference fuels modeled by a semidetailed chemical kinetic model

    SciTech Connect

    Andrae, J.C.G.; Brinck, T.; Kalghatgi, G.T.

    2008-12-15

    A semidetailed mechanism (137 species and 633 reactions) and new experiments in a homogeneous charge compression ignition (HCCI) engine on the autoignition of toluene reference fuels are presented. Skeletal mechanisms for isooctane and n-heptane were added to a detailed toluene submechanism. The model shows generally good agreement with ignition delay times measured in a shock tube and a rapid compression machine and is sensitive to changes in temperature, pressure, and mixture strength. The addition of reactions involving the formation and destruction of benzylperoxide radical was crucial to modeling toluene shock tube data. Laminar burning velocities for benzene and toluene were well predicted by the model after some revision of the high-temperature chemistry. Moreover, laminar burning velocities of a real gasoline at 353 and 500 K could be predicted by the model using a toluene reference fuel as a surrogate. The model also captures the experimentally observed differences in combustion phasing of toluene/n-heptane mixtures, compared to a primary reference fuel of the same research octane number, in HCCI engines as the intake pressure and temperature are changed. For high intake pressures and low intake temperatures, a sensitivity analysis at the moment of maximum heat release rate shows that the consumption of phenoxy radicals is rate-limiting when a toluene/n-heptane fuel is used, which makes this fuel more resistant to autoignition than the primary reference fuel. Typical CPU times encountered in zero-dimensional calculations were on the order of seconds and minutes in laminar flame speed calculations. Cross reactions between benzylperoxy radicals and n-heptane improved the model predictions of shock tube experiments for {phi}=1.0 and temperatures lower than 800 K for an n-heptane/toluene fuel mixture, but cross reactions had no influence on HCCI simulations. (author)

  5. Investigation of coal structure

    SciTech Connect

    Not Available

    1993-01-01

    The method was applied to standard polymers under the same condition above. The particle size distribution with volume diameters of polyvinylpyrrolidone (average molecular mass; 10,000) was measured at sample/solvent = 0.50 g/100 ml. This polymer readily dissolve in methanol and water, while the polymer does not dissolve in n-hexane and toluene, and toluene is a slightly better solvent than n-hexane. Figure 3 shows the particle size distributions in n-hexane (a) and toluene (b-1 and -2). The distribution in toluene changed time to time, and two representative distributions are shown. The mean volume diameters-were 14 [mu]m in n-hexane and 18 and 31 [mu]m in toluene. The particle size distribution of cross-linked polyvinylpyrrolidone was further examined in methanol and n-hexane. Figure 4 compares these distributions with scanned counts at sample/solvent = 0.50 g/100 ml. As a significant portion of particles was over 250 [mu]m with volume diameters, the distributions are presented with scanned counts. Figure 4 compared the specific swelling ratio (Q') versus sample/solvent (w/w %) in the same solvents for this sample. It is seen that methanol is a good solvent than n-hexane and swells the sample. It is also seen that the swelling is dependent on the sample concentration. Therefore, the particle size in good solvent methanol is expected to be larger due to swelling. However, the particle size was smaller in methanol than in n-hexane (Figure 4). The dependence of sample concentration on solvent swelling in methanol (Figure 5) is interpreted as follows: Polymer particles disaggregated at low sample concentration and the interparticle voidage of the swollen polymer after centrifugation changed depending upon disaggregation.

  6. Investigation of coal structure. Quarterly report, October 1, 1992--December 31, 1992

    SciTech Connect

    Not Available

    1993-01-01

    The method was applied to standard polymers under the same condition above. The particle size distribution with volume diameters of polyvinylpyrrolidone (average molecular mass; 10,000) was measured at sample/solvent = 0.50 g/100 ml. This polymer readily dissolve in methanol and water, while the polymer does not dissolve in n-hexane and toluene, and toluene is a slightly better solvent than n-hexane. Figure 3 shows the particle size distributions in n-hexane (a) and toluene (b-1 and -2). The distribution in toluene changed time to time, and two representative distributions are shown. The mean volume diameters-were 14 {mu}m in n-hexane and 18 and 31 {mu}m in toluene. The particle size distribution of cross-linked polyvinylpyrrolidone was further examined in methanol and n-hexane. Figure 4 compares these distributions with scanned counts at sample/solvent = 0.50 g/100 ml. As a significant portion of particles was over 250 {mu}m with volume diameters, the distributions are presented with scanned counts. Figure 4 compared the specific swelling ratio (Q`) versus sample/solvent (w/w %) in the same solvents for this sample. It is seen that methanol is a good solvent than n-hexane and swells the sample. It is also seen that the swelling is dependent on the sample concentration. Therefore, the particle size in good solvent methanol is expected to be larger due to swelling. However, the particle size was smaller in methanol than in n-hexane (Figure 4). The dependence of sample concentration on solvent swelling in methanol (Figure 5) is interpreted as follows: Polymer particles disaggregated at low sample concentration and the interparticle voidage of the swollen polymer after centrifugation changed depending upon disaggregation.

  7. A coupled implicit method for chemical non-equilibrium flows at all speeds

    NASA Technical Reports Server (NTRS)

    Shuen, Jian-Shun; Chen, Kuo-Huey; Choi, Yunho

    1993-01-01

    The present time-accurate coupled-solution procedure addresses the chemical nonequilibrium Navier-Stokes equations over a wide Mach-number range uses, in conjunction with the strong conservation form of the governing equations, five unknown primitive variables. The numerical tests undertaken address steady convergent-divergent nozzle flows with air dissociation/recombination, dump combustor flows with n-pentane/air chemistry, and unsteady nonreacting cavity flows.

  8. Numerical study of multicomponent droplet vaporization at near critical conditions

    NASA Technical Reports Server (NTRS)

    Hsieh, Kwang-Chung; Shuen, Jian-Shun; Yang, Vigor

    1988-01-01

    A comprehensive numerical analysis of multicomponent droplet vaporization at near critical conditions has been carried out. The model is based on the full time-dependent conservation equations and accommodates various important high-pressure phenomena. As an example, the case involving a two-component (n-pentane and n-octane) fuel droplet in nitrogen gas is studied. The influences of transient effects, surface regression, ambient gas solubility, and phase-equilibrium relations on vaporization mechanisms are examined in detail.

  9. High-pressure soot formation and diffusion flame extinction characteristics of gaseous and liquid fuels

    NASA Astrophysics Data System (ADS)

    Karatas, Ahmet Emre

    High-pressure soot formation and flame stability characteristics were studied experimentally in laminar diffusion flames. For the former, radially resolved soot volume fraction and temperature profiles were measured in axisymmetric co-flow laminar diffusion flames of pre-vaporized n-heptane-air, undiluted ethylene-air, and nitrogen and carbon dioxide diluted ethylene-air at elevated pressures. Abel inversion was used to re-construct radially resolved data from the line-of-sight spectral soot emission measurements. For the latter, flame extinction strain rate was measured in counterflow laminar diffusion flames of C1-4 alcohols and hydrocarbon fuels of n-heptane, n-octane, iso-octane, toluene, Jet-A, and biodiesel. The luminous flame height, as marked by visible soot radiation, of the nitrogen- and helium-diluted n-heptane and nitrogen- and carbon dioxide-diluted ethylene flames stayed constant at all pressures. In pure ethylene flames, flame heights initially increased with pressure, but changed little above 5 atm. The maximum soot yield as a function of pressure in nitrogen-diluted n-heptane diffusion flames indicate that n-heptane flames are slightly more sensitive to pressure than gaseous alkane hydrocarbon flames at least up to 7 atm. Ethylene's maximum soot volume fractions were much higher than those of ethane and n-heptane diluted with nitrogen (fuel to nitrogen mass flow ratio is about 0.5). Pressure dependence of the peak carbon conversion to soot, defined as the percentage of fuel's carbon content converted to soot, was assessed and compared to previous measurements with other gaseous fuels. Maximum soot volume fractions were consistently lower in carbon dioxide-diluted flames between 5 and 15 atm but approached similar values to those in nitrogen-diluted flames at 20 atm. This observation implies that the chemical soot suppression effect of carbon dioxide, previously demonstrated at atmospheric pressure, is also present at elevated pressures up to 15 atm, but fades off beyond 15 atm. In flame stability experiments, the extinction strain rates increased with decreasing dilution. In general, the fuels with higher carbon number and fuels with more compact structures were found to be more prone to extinction. Counterflow laminar diffusion flames established at the impingement of reactants with a top-hat (axially uniform) velocity profile were found to be more resistant to extinction than those with a parabolic exit velocity profile. Multiple solutions to the flame stability were observed for certain hydrocarbons.

  10. Laboratory Evaluations of the Fractions Efficacy of Annona senegalensis (Annonaceae) Leaf Extract on Immature Stage Development of Malarial and Filarial Mosquito Vectors

    PubMed Central

    Lame, Younoussa; Nukenine, Elias Nchiwan; Pierre, Danga Yinyang Simon; Elijah, Ajaegbu Eze; Esimone, Charles Okechukwu

    2015-01-01

    Background: Within the framework to control mosquitoes, ovicidal, larvicidal and pupicidal activity of Annona senegalensis leaf extract and its 4 fractions against Anopheles gambiae and Culex quinquefasciatus were evaluated in the laboratory conditions. Methods: Ovicidal test was performed by submitting at least 100 eggs of mosquitoes to 125, 250, 500, 1000 and 2000 ppm concentrations, while larvicidal and pupicidal effects were assessed by submitting 25 larvae or pupae to the concentrations of 2500, 1250, 625 and 312.5 ppm of plant extract or fractions of A. senegalensis. Results: The eggs of An. gambiae were most affected by N-hexane (0.00% hatchability) and chloroform (03.67% hatchability) fractions compared to Cx. quinquefasciatus where at least 25 % hatchability were recorded at 2000 ppm. For larvicidal test, N-hexane (LC50= 298.8 ppm) and chloroform (LC50= 418.3 ppm) fractions were more effective than other fractions on An. gambiae larvae while, a moderate effectiveness was also observed with N-hexane (LC50= 2087.6 ppm), chloroform (LC50= 9010.1 ppm) fractions on Cx. quinquefasciatus larvae. The highest mortality percent of the pupae were also recorded with N-hexane and chloroform fractions on An. gambiae at 2500 ppm. As for Cx. quinquefasciatus only 50 % and 36 % mortality were recorded with N-hexane and chloroform fractions respectively. Conclusion: The extract of A. senegalensis was toxic on immature stage of mosquito species tested. By splitting methanolic crude extract, only N-hexane and chloroform fractions were revealed to possess a mosquitocidal effects and could be considered and utilized for future immature mosquito vectors control. PMID:26623434

  11. Simple solvothermal synthesis of hydrophobic magnetic monodispersed Fe{sub 3}O{sub 4} nanoparticles

    SciTech Connect

    Liu, Jing; Wang, Lu; Wang, Jing; Zhang, Lantong

    2013-02-15

    Graphical abstract: A facile method to produce monodispersed magnetite nanoparticles is based on the solvothermal reaction of iron acetylacetonate (Fe(acac)3) decomposition. The sizes ranged from 7 to 12 nm, which could be controlled by adjusting the volume ratio of oleylamine to n-hexane. Display Omitted Highlights: ? The solvethermal reaction of Fe(acac){sub 3} decomposition was carried out at mild temperature in the presence of oleylamine and n-hexane. ? The size of nanocrystals is controlled by adjusting the volume ratio of oleylamine to n-hexane. ? The low-boiling-point solvent n-hexane offered autogenous pressure parameter after gasified in the reaction temperature. ? The as prepared hydrophobic monodisperse Fe{sub 3}O{sub 4} NPs can be used to prepare the magnetic micelles for future biomedical applications. -- Abstract: A new solvothermal method is proposed for the preparation of Fe{sub 3}O{sub 4} nanoparticles (NPs) from iron acetylacetonate in the presence of oleylamine and n-hexane. The products are characterized by X-ray powder diffraction, infrared (IR) spectroscopy, transmission electron microscopy, thermogravimetry/differential thermogravimetry (TG/DTG) analysis, and vibrating sample magnetometery. The new procedure yields superparamagnetic monodispersed Fe{sub 3}O{sub 4} particles with sizes ranging from 7 nm to 12 nm. The nanocrystal sizes are controlled by adjusting the volume ratio of oleylamine to n-hexane. IR and TG/DTG analyses indicate that the oleylamine molecules, as stabilizers, are adsorbed on the surface of Fe{sub 3}O{sub 4} NPs as bilayer adsorption models. The surface adsorption quantities of oleylamine on 7.5 and 10.4 nm-diameter Fe{sub 3}O{sub 4} NPs are 18% and 11%, respectively. The hydrophobic surface of the obtained nanocrystals is passivated by adsorbed organic solvent molecules. These molecules provide stability against agglomeration, enable solubility in nonpolar solvents, and allow the formation of magnetic polymer micelles.

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

    PubMed Central

    Kawashima, Yasushi

    2013-01-01

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

  13. Combined small-angle x-ray scattering/extended x-ray absorption fine structure study of coated Co nanoclusters in bis(2-ethylhexyl)sulfosuccinate

    NASA Astrophysics Data System (ADS)

    Longo, A.; Giordano, F.; Giannici, F.; Martorana, A.; Portale, G.; Ruggirello, A.; Turco Liveri, V.

    2009-06-01

    Chemically stable cobalt nanostructures have been prepared with Co(II) reduction in the confined space of cobalt bis(2-ethylhexyl)sulfosuccinate, Co(AOT)2, reverse micelles dispersed in n-heptane. The reaction was carried out by adding a solution of sodium borohydride in ethanol (1% weight) to a 0.2M micellar solution of Co(AOT)2 in n-heptane at a reductant to Co(II) molar ratio of 4. This procedure involves the rapid formation of surfactant-coated Co nanoparticles followed by their slow separation as nanostructures embedded in a sodium bis(2-ethylhexyl)sulfosuccinate matrix. The resulting composites, characterized by extended x-ray absorption fine structure and small-angle x-ray scattering, showed the presence of subnanometer sized cobalt nanoparticles aggregated together to form elongated structures coated by the surfactant molecules.

  14. Evaluation of the performance of commercially available polysaccharide-based chiral stationary phases after multicycle operation in multimodal elution mode.

    PubMed

    Török, Gabriella; Goetelen, Ludwig; Luyckx, Raf; Van Broeck, Peter

    2005-09-15

    The performance of four commercially available polysaccharide-based chiral stationary phases, Chiralcel OD, Chiralcel OJ, Chiralpak AD and Chiralpak AS was evaluated after several cycles of extended multimodal operations. Acetonitrile, methanol, ethanol and their mixtures were chosen for polar-organic mobile phases, ethanol-n-heptane mixture and n-heptane were selected for normal-phase mode. Retention factor (k), selectivity (alpha), resolution (Rs) and theoretical plate count (N) were the chosen parameters to describe the column performance. One racemate for which all four columns have shown enantioselectivity was chosen as test compound. After 15 cycles of multimodal operations a slight decrease was seen in the retention factors (k) however, column efficiency, selectivity (alpha) and resolution (Rs) were maintained. PMID:15927435

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

    PubMed

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

    2013-07-17

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

  16. Molecular structure and component blending effects on knock related chemistry

    SciTech Connect

    Brezinsky, K.; Dryer, F.L.

    1987-01-01

    Atmospheric pressure flow reactor experiments were conducted on the oxidation and pyrolysis of n-octane and iso-octane and the oxidation of blends of iso-octane and n-heptane have led to the conclusions that a) the difference in knocking tendency of fuels may result primarily from the comparative oxidation rates of the intermediates rather than the rate of attack on the initial fuel molecule, b) certain small unsaturated hydrocarbons interfere with the oxidation of other intermediates and serve as model compounds for the development of octane number enhancers, c) high temperature homogeneous oxidation chemistry of n-heptane/iso-octane mixtures and single component paraffin fuels can be correlated with the global phenomena of octane number measurement in a test engine, d) the contribution of thermal and oxidative processes to the rapid decay of the initial fuel can be evaluated from rate parameters from pyrolysis studies of pure hydrocarbon fuels.

  17. Detailed kinetic models for the low-temperature auto ignition of gasoline surrogates

    E-print Network

    Bounaceur, Roda; Fournet, René; Warth, Valérie; Battin-Leclerc, Frédérique

    2009-01-01

    In the context of the search for gasoline surrogates for kinetic modeling purpose, this paper describes a new model for the low-temperature auto-ignition of n-heptane/iso-octane/hexene/toluene blends for the different linear isomers of hexene. The model simulates satisfactory experimental results obtained in a rapid compression machine for temperatures ranging from 650 to 850 K in the case of binary and ternary mixtures including iso octane, 1-hexene and toluene. Predictive simulations have also been performed for the autoignition of n heptane/iso octane/hexene/toluene quaternary mixtures: the predicted reactivity is close to that of pure iso octane with a retarding effect when going from 1- to 3-alkene.

  18. HPLC determination of flumethrin, deltamethrin, cypermethrin, and cyhalothrin residues in the milk and blood of lactating dairy cows.

    PubMed

    Bissacot, D Z; Vassilieff, I

    1997-09-01

    A procedure to determine residue concentrations of synthetic pyrethroid insecticides (flumethrin, deltamethrin, cypermethrin and cyhalothrin) in the milk and blood of lactating dairy cows was developed. Extraction was performed with acetoritrile, n-hexane partitioning, and silica gel column cleanup with n-hexane and diethyl ether. Analysis was carried out by high-performance liquid chromatography and ultraviolet detection. Recovery of the four pyrethroids averaged 78 to 91% with a minimum detectable concentration of 0.001 mg/kg. The method was reproducible and sensitive. PMID:9288595

  19. Understanding nanofluid stability through molecular simulation

    NASA Astrophysics Data System (ADS)

    Dang, Liem X.; Annapureddy, Harsha V. R.; Sun, Xiuquan; Thallapally, Praveen K.; Peter McGrail, B.

    2012-11-01

    Molecular dynamics simulations were carried out to systematically study solvation and nanoparticle-particle interactions in n-hexane, water and methanol solvents. The dynamics of the n-hexane molecules was significantly influenced by the solvated nanoparticles. Water and methanol show significant structural signatures binding to the metal coordination sites of the nanoparticles while liquid hexane does not. The computed free energy profiles illustrate that the associations between nanoparticles in solution are stable and depend on the relative orientation of them. Also, these profiles indicate a low interaction potential between nanoparticles in methanol, confirming experimental observations of inherent nanofluid stability without need for added surfactant.

  20. Experiments And Model Development For The Investigation Of Sooting And Radiation Effects In Microgravity Droplet Combustion

    NASA Technical Reports Server (NTRS)

    Yozgatligil, Ahmet; Choi, Mun Young; Dryer, Frederick L.; Kazakov, Andrei; Dobashi, Ritsu

    2003-01-01

    This study involves flight experiments (for droplets between 1.5 to 5 mm) and supportive ground-based experiments, with concurrent numerical model development and validation. The experiments involve two fuels: n-heptane, and ethanol. The diagnostic measurements include light extinction for soot volume fraction, two-wavelength pyrometry and thin-filament pyrometry for temperature, spectral detection for OH chemiluminescence, broadband radiometry for flame emission, and thermophoretic sampling with subsequent transmission electron microscopy for soot aerosol property calculations.

  1. Ignition Delays of Alkyl Thiophosphites with White and Red Fuming Nitric Acids Within Temperature Range 80 to -105 F

    NASA Technical Reports Server (NTRS)

    Miller, Riley O; Ladanyi, Dezso J

    1953-01-01

    Ignition delays of alkyl thiophosphites were obtained in a modified open-cup apparatus and a small-scale rocket engine apparatus. At -40 F, mixed alkyl thiophosphites gave short delays with white fuming nitric acid containing 2 percent water and red fuming nitric acids of widely varying compositions. At -40 F and higher, triethyl trithiophosphite blended with as much as 40 percent n-heptane gave satisfactory self-igniting properties at temperatures as low as -76 F.

  2. Fire Smoke Particle Size Measurement Based on the Multiwavelength and Multiangle Light Scattering Method

    NASA Astrophysics Data System (ADS)

    Shu, Xue-Ming; Fang, Jun; Shao, Quan; Yuan, Hong-Yong; Fan, Wei-Cheng

    2006-02-01

    A multiwavelength and multiangle mathematical model (MWMA) is developed, and the corresponding influence factors of the model are analysed by the numerical calculation. Combined with measurement data of radiation flux and the curve in theoretical calculation, particle sizes of different materials can be obtained. It is found that smoke particle size gradually decreases from land plaster, cotton wick, beech wood, polyurethane, sandalwood, decahydronaphthalene, to N-heptane.

  3. Study of absorption spectra of gasolines and other hydrocarbon mixtures in the second overtone region of the CH3, CH2, CH groups

    NASA Astrophysics Data System (ADS)

    Muradov, V. G.; Sannikov, D. G.

    2007-03-01

    We have obtained experimental and model absorption spectra for individual hydrocarbons (toluene, benzene, n-heptane, and iso-octane) and their mixtures in the near IR range (? = 1080 1220 nm). We model the spectra of nonsynthetic gasolines obtained under the same conditions by combining the spectra of three pure hydrocarbons. We show that the octane number of the studied gasoline is linearly related to the toluene (or benzene) concentrations in the model mixture.

  4. Efficient High-Pressure State Equations

    NASA Technical Reports Server (NTRS)

    Harstad, Kenneth G.; Miller, Richard S.; Bellan, Josette

    1997-01-01

    A method is presented for a relatively accurate, noniterative, computationally efficient calculation of high-pressure fluid-mixture equations of state, especially targeted to gas turbines and rocket engines. Pressures above I bar and temperatures above 100 K are addressed The method is based on curve fitting an effective reference state relative to departure functions formed using the Peng-Robinson cubic state equation Fit parameters for H2, O2, N2, propane, methane, n-heptane, and methanol are given.

  5. Transition metal catalysis in the generation of petroleum: A genetic anomaly in Ordovician oils

    SciTech Connect

    Mango, F.D. )

    1992-10-01

    The transition metals, captured from sedimentary waters by chlorophyll, have been proposed as the catalytic agents that convert n-alkane biolipids into the rearranged light hydrocarbons in petroleum. Certain ancient oils (Ordovician) display a depletion in chlorophyll, suggesting that they may have been derived from sedimentary rocks also depleted in transition metals. These oils show anomalously high concentrations of n-heptane relative to their respective rearranged isoalkane and cycloalkane products. This extraordinary enrichment in light n-alkanes appears unique to the chlorophyll-deficient Ordovician oils. The high concentrations of n-heptane may have resulted from the thermal cracking of higher n-alkanes, which are known to be dominant components of the kerogenous precursors to the Ordovician oils. However, the methylhexanes, which have no thermolytic precursors enriched in the kerogenous source, show a proportionate increase in concentration. The contention, therefore, that thermal cracking might explain the n-heptane anomaly is untenable since a kerogenous starting material enriched in n-alkanes and depleted in isoalkanes cannot reasonably crack to a light hydrocarbon product enriched in both n-alkanes and isoalkanes. According to a postulated catalytic cycle, n-alkane and isoalkane concentrations are controlled by the relative rates of two divergent pathways. If the various transition metals that may catalyze these reactions differ in activity, then a unique distribution of metals created by a chlorophyll deficiency could explain the Ordovician anomaly.

  6. Fuel-Specific Effect of Exhaust Gas Residuals on HCCI Combustion: A Modeling Study

    SciTech Connect

    Szybist, James P

    2008-01-01

    A modeling study was performed to investigate fuel-specific effects of exhaust gas recirculation (EGR) components on homogeneous charge compression ignition (HCCI) combustion at conditions relevant to the negative valve overlap (NVO) strategy using CHEMKIN-PRO. Four single-component fuels with well-established kinetic models were chosen: n-heptane, iso-octane, ethanol, and toluene. These fuels were chosen because they span a wide range of fuel chemistries, and produce a wide compositions range of complete stoichiometric products (CSP). The simulated engine conditions combined a typical spark ignition engine compression ratio (11.34) and high intake charge temperatures (500-550 K) that are relevant to NVO HCCI. It was found that over the conditions investigated, all the fuels had overlapping start of combustion (SOC) phasing, despite the wide range in octane number (RON = 0 to 120). The effect of the EGR components CO2 and H2O was to suppress the compression temperature because of their higher heat capacities, which retarded SOC. For a concentration of O2 higher than the stoichiometric amount, or excess O2, there was an effect of advancing SOC for n-heptane, iso-octane, and toluene, but SOC for ethanol was not advanced. Low temperature heat release (LTHR) for n-heptane was also found to be highly dependent on excess O2, and mild endothermic reaction was observed for cases when excess O2 was not present.

  7. Purification of antibiotics from the biocontrol agent Streptomyces anulatus S37 by centrifugal partition chromatography.

    PubMed

    Couillerot, Olivier; Loqman, Souad; Toribio, Alix; Hubert, Jane; Gandner, Léa; Nuzillard, Jean-Marc; Ouhdouch, Yedir; Clément, Christophe; Barka, Essaid Ait; Renault, Jean-Hugues

    2014-01-01

    A novel actinomycete strain, Streptomyces anulatus S37, has been isolated from the rhizosphere of healthy Moroccan Vitis vinifera on the basis on its ability to promote grapevine growth and to induce natural defences against various phytopathogens. In the present work, the main bioactive metabolites produced by S. anulatus S37 were isolated. A crude n-BuOH extract of the S37 fermentation broth was firstly partitioned in a biphasic solvent system composed of n-heptane, methanol, and water (5:1.5:3.5, v/v). The most active organic fraction (1.1g) as revealed by TLC-bioautography was subsequently separated by a two-step centrifugal partition chromatography procedure. The first separation was performed in the ascending mode at 6mL/min with the biphasic solvent system n-heptane, ethyl acetate, methanol and water (2:1:2:1, v/v), to finally recover 40mg of a pure compound identified as streptochlorin by NMR spectroscopy. In a second separation, the solvent system n-heptane, acetonitrile, and water (5:5:4, v/v) was used in the ascending mode at 3mL/min to purify 135mg of nigericin and 53mg of piericidin A1. Assays performed with the three compounds have confirmed their inhibitory impact on the growth of Botryris cinerea in dual confrontation and also on V. vinifera L. plantlets. PMID:24291716

  8. The oxidation of a gasoline surrogate in the negative temperature coefficient region

    SciTech Connect

    Lenhert, David B.; Miller, David L.; Cernansky, Nicholas P.; Owens, Kevin G.

    2009-03-15

    This experimental study investigated the preignition reactivity behavior of a gasoline surrogate in a pressurized flow reactor over the low and intermediate temperature regime (600-800 K) at elevated pressure (8 atm). The surrogate mixture, a volumetric blend of 4.6% 1-pentene, 31.8% toluene, 14.0% n-heptane, and 49.6% 2,2,4-trimethyl-pentane (iso-octane), was shown to reproduce the low and intermediate temperature reactivity of full boiling range fuels in a previous study. Each of the surrogate components were examined individually to identify the major intermediate species in order to improve existing kinetic models, where appropriate, and to provide a basis for examining constituent interactions in the surrogate mixture. n-Heptane and 1-pentene started reacting at 630 K and 640 K, respectively, and both fuels exhibited a strong negative temperature coefficient (NTC) behavior starting at 700 and 710 K, respectively. Iso-octane showed a small level of reactivity at 630 K and a weak NTC behavior starting at 665 K. Neat toluene was unreactive at these temperatures. The surrogate started reacting at 630 K and exhibited a strong NTC behavior starting at 693 K. The extent of fuel consumption varied for each of the surrogate constituents and was related to their general autoignition behavior. Most of the intermediates identified during the surrogate oxidation were species observed during the oxidation of the neat constituents; however, the surrogate mixture did exhibit a significant increase in intermediates associated with iso-octane oxidation, but not from n-heptane. While neat toluene was unreactive at these temperatures, in the mixture it reacted with the radical pool generated by the other surrogate components, forming benzaldehyde, benzene, phenol, and ethyl-benzene. The observed n-heptane, iso-octane, and surrogate oxidation behavior was compared to predictions using existing kinetic models. The n-heptane model reasonably predicted the disappearance of the fuel, but overpredicted the formation of several of the smaller intermediates. The iso-octane model significantly overpredicted the reaction of the fuel and formation of the intermediates. The 1-pentene model reasonably predicted the fuel consumption, but underestimated the importance of radical addition to the double bond. The results of this study provide a critical experimental foundation for the investigation of surrogate mixtures and for validation of kinetic models. (author)

  9. Fischer-Tropsch synthesis in supercritical reaction media. Progress report, October 1, 1992--December 31, 1992

    SciTech Connect

    Subramaniam, B.; Bochniak, D.; Snavely, K.

    1993-01-01

    Our goals for this quarter were to complete construction of the reactor and analytical units for carrying out Fischer-Tropsch (F-T) synthesis in liquid (n-hexadecane) and in supercritical n-hexane phases. Progress during this quarter was slower than expected.

  10. Fischer-Tropsch synthesis in supercritical reaction media

    SciTech Connect

    Subramaniam, B.; Bochniak, D.; Snavely, K.

    1993-01-01

    Our goals for this quarter were to complete construction of the reactor and analytical units for carrying out Fischer-Tropsch (F-T) synthesis in liquid (n-hexadecane) and in supercritical n-hexane phases. Progress during this quarter was slower than expected.

  11. Supporting Information Chen et al. 10.1073/pnas.0707046105

    E-print Network

    Cheng, Ji-Xin

    in dichloromethane (DCM) (25 ml) and precipitated against excess n-hexane twice. White powder of PDLLA). Elution was performed with a linear NaCl gradient from 0 to 1 M (citrate buffer, pH 5.0). Fractions were

  12. KINETICS AND SELECTIVITY OF DEEP CATALYTIC OXIDATION OF VOLATILE ORGANIC COMPOUND MIXTURES

    EPA Science Inventory

    The paper gives results of a fundamental study of low-temperature deep (complete) oxidation of n-hexane, benzene, and ethyl-acetate over a 0.1% Pt, 3% Ni/gamma-AL203 catalyst. (NOTE: Deep catalytic combustion of volatile organic compounds--VOCs--is emerging as an important emissi...

  13. In vitro antioxidant activity and inhibitory effect, on oleic acid-induced hepatic steatosis, of fractions and subfractions from oat (Avena sativa L.) ethanol extract

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Oats (Avena sativa L.) were extracted with 80% aqueous ethanol and the extract was successively isolated by liquid-liquid partition to yield n-hexane, ethyl acetate, n-butanol and water layers. Among these extractions the ethyl acetate (EA) layer exhibited the highest total phenolic content (TPC), t...

  14. Ethyl acetate-n-butanol gradient solvent system for high-speed countercurrent chromatography to screen bioactive substances in okra.

    PubMed

    Ying, Hao; Jiang, Heyuan; Liu, Huan; Chen, Fangjuan; Du, Qizhen

    2014-09-12

    High-speed countercurrent chromatographic separation (HSCCC) possesses the property of zero-loss of sample, which is very useful for the screening of bioactive components. In the present study, the ethyl acetate-n-butanol gradient HSCCC solvent system composed of n-hexane-ethyl acetate-n-butanol-water was investigated for the screening of bioactive substances. To screen the antiproliferative compounds in okra extract, we used the stationary phase ethyl acetate-n-butanol-water (1:1:10) as the stationary phase, and eluted the antiproliferative components by 6-steps of gradient using mobile phases n-hexane-ethyl acetate (1:2), n-hexane-ethyl acetate (1:4), n-hexane-ethyl acetate (0:4), n-butanol-ethyl acetate (1:4) n-butanol-ethyl acetate (1:2), n-butanol-ethyl acetate (2:2), and n-butanol-ethyl acetate (2:1). The fractions collected from HSCCC separation with the gradient solvent system were assayed for antiproliferative activity against cancer cells. Bioactive components were identified: a major anti-cancer compound, 4'-hydroxy phenethyl trans-ferulate, with middle activity, and a minor anti-cancer compound, carolignan, with strong activity. The result shows that the gradient solvent system is potential for the screening of bioactive compounds from natural products. PMID:25069743

  15. Cytotoxicity and modulation of cancer-related signaling by (Z)- and (E)- 3,4,3´,5´ tetramethoxystilbene isolated from Eugenia rigida

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The leaves of E. rigida DC (Myrtaceae) were collected from Puerto Rico in March, 2006. The sample was identified by Mr. F. Axelrod and a voucher specimen (3008783) was deposited at the Herbarium of Missouri Botanical Garden, St. Louis, MO. Air-dried powdered leaves (107 g) were soaked in n-hexane an...

  16. Functional assessment of the strength of solid acid catalysts Josef Macht, Robert T. Carr, Enrique Iglesia *

    E-print Network

    Iglesia, Enrique

    prevalent during dehydration catalysis. These effects of reaction media (and treatment protocols) reflect dehydration n-Hexane isomerization Sulfated zirconia Tunstated zirconia Perfluorosulfonic acid resins for dehydration and isomerization reactions and DPE values on Keggin polyoxometalates and H-BEA solids with known

  17. A new ester coumarin from Ferula Persica wild, indigenous to Iran.

    PubMed

    Razavi, Seyed Mehdi; Janani, Mehrnoush

    2015-01-01

    Ferula persica wild (Apiaceae) is a perennial herb indigenous to Iran. It has been used in folk medicine for treatment of diabetes, lowering of blood pressure and for antispasmodic, carminative, laxative and expectorant effects in central Iran. Dried ground roots of F. persica (150 g) were extracted sequentially with n-hexane, dichloromethane and methanol (MeOH), 500 ml each, using a Soxhlet apparatus. The n-hexane extract of the roots (3 g) was subjected to vacuum liquid chromatography on silica gel, eluting with solvent mixtures of increasing polarity: 100% n-hexane-ethyl acetate (EtOAc), to yield a number of fractions, Fraction 4 (80% EtOAc in n-hexane) was further analysed by preparative TLC (mobile phase was 12% acetone in chloroform) to yield a coumarin ester (10.1 mg, Rf = 0.31, blue florescent). The structure of the isolated compound was elucidated by spectroscopic means. The compound is 7-O-(4,8,12 -trihydroxy-4,8,12-trimethyl-tridecanoyl)-coumarin, named, ferulone C as a new natural product. PMID:25427054

  18. Control of charcoal rot fungus Macrophomina phaseolina by extracts of Datura metel.

    PubMed

    Javaid, Arshad; Saddique, Amna

    2012-01-01

    Methanolic leaf and fruit extracts of Datura metel were found highly effective in suppressing against Macrophomina phaseolina, the cause of charcoal rot disease. These extracts were further subjected to successive fractionation with n-hexane, chloroform, ethyl acetate and n-butanol. All the concentrations (3.125-200?mg?mL?¹) of chloroform, ethyl acetate and n-butanol fractions of leaf extract, and n-hexane fraction of fruit extract completely inhibited the target fungal growth. Two compounds A and B from the n-hexane fraction of fruit extract and compound C from n-butanol fraction of leaf extract were obtained by TLC. Compound B exhibited the best antifungal activity with an MIC value of 7.81?µg?mL?¹ that was at par with that of commercial fungicide mancozeb (80% w/w). This study concludes that M. phaseolina can be effectively controlled by natural antifungal compounds in n-hexane fraction of methanolic fruit extract of D. metel. PMID:22004473

  19. 40 CFR 60.485 - Test methods and procedures.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... mixture of methane or n-hexane and air at a concentration of about, but less than, 10,000 ppm methane or n... the target compound(s) are those listed in Section 1.1 of ASTM D6420-99, and the target...

  20. Numerical solution of the nonequilibrium square-gradient model and verification of local equilibrium for the Gibbs surface in a two-phase binary mixture

    E-print Network

    Kjelstrup, Signe

    equilibrium for the Gibbs surface in a two-phase binary mixture K. S. Glavatskiy1 and D. Bedeaux1,2 1 paper to a binary mixture of cyclohexane and n-hexane. We use the square gradient model that the surface in a stationary state of the mixture can be described in terms of Gibbs excess densities, which

  1. Selective solid-phase extraction of cholesterol using molecularly imprinted polymers and its application in different biological samples.

    PubMed

    Shi, Yun; Zhang, Jiang-Hua; Shi, Dan; Jiang, Ming; Zhu, Ye-Xiang; Mei, Su-Rong; Zhou, Yi-Kai; Dai, Kang; Lu, Bin

    2006-11-16

    Non-covalent molecularly imprinted polymers (MIPs) of cholesterol were prepared by UV initiated polymerization. A polymer that had the highest binding selectivity and capability was used as solid-phase extraction (SPE) sorbents for direct extraction of cholesterol from different biological samples (human serum, cow milk, yolk, shrimp, pork and beef). The extraction conditions of molecularly imprinted SPE (MISPE) were optimized and the optimum protocol was: conditioning MISPE cartridges with n-hexane, loading with n-hexane, washing with n-hexane and n-hexane:toluene=9:1, respectively, then eluting with chloroform:ethanol:acetic acid=3:1:1. Cholesterol MISPE selectively recognized, effectively trapped and pre-concentrated cholesterol over a concentration range of 10-80 microg/mL. Recoveries ranged from 80.6% to 92.7%, with R.S.D. lower than 9.8%. Under the optimal condition, MISPE recoveries of spiked human serum, yolk, cow milk, shrimp, pork and beef were 91.1%, 80.4%, 86.6%, 78.2%, 81.4% and 80.1%, respectively. Compared with C18 SPE, almost all of the matrix interferences were removed after MISPE, and better baselines and higher selectivity were achieved. PMID:16859856

  2. 40 CFR 63.7824 - What test methods and other procedures must I use to establish and demonstrate initial compliance...

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ...) using Method 25 in 40 CFR part 60, appendix A. Record the sampling date and time, sampling results, and... Method 25 (40 CFR part 60, appendix A), milligrams per dry standard cubic meters (mg/dscm) for each day... day, and analyze the composited samples using Method 9071B, “n-Hexane Extractable Material(HEM)...

  3. VANADIUM PHOSPHORUS OXIDE AS AN EFFICIENT CATALYST FOR HYDROCARBON OXIDATIONS USING HYDROGEN PEROXIDE

    EPA Science Inventory

    Calcined vanadium phosphorus oxide (VPO) prepared by an organic route is found to be an efficient catalyst for the oxidation of various alkanes such as cyclopentane, cyclohexane, n-hexane, cycloheptane, cyclooctane, cyclodecane and adamantane in acetonitrile solvent using the env...

  4. SPECTROFLUOROMETRIC AND HIGH-PERFORMANCE LIQUID CHROMATOGRAPHIC DETERMINATION OF a-TOCOPHEROL ACETATE IN OLIVE OIL

    Technology Transfer Automated Retrieval System (TEKTRAN)

    A high performance liquid chromatographic (HPLC) method was developed for the quantitative determination of '-acetate tocopherol in olive oil. After extracts in n-hexane, acetate '- tocopherol were quantitatively analyzed by HPLC with fluorimetric detector. The presence of acetate '- tocopherol in...

  5. Neuropathy in a petrol sniffer.

    PubMed Central

    Hall, D M; Ramsey, J; Schwartz, M S; Dookun, D

    1986-01-01

    A 4 year old boy developed a profound motor neuropathy after repeated deliberate inhalation of petroleum vapour. The condition was characterised by extreme slowing of the nerve conduction velocity. He made a gradual recovery over six months. The neuropathy was attributed to the N-hexane component of petroleum. PMID:3021070

  6. Novel modified zeolites for energy-efficient hydrocarbon separations.

    SciTech Connect

    Arruebo, Manuel; Dong, Junhang; Anderson, Thomas (Burns and McDonnell, Kansas City, MO); Gu, Xuehong; Gray, Gary (Goodyear Chemical Company, Akron, OH); Bennett, Ron (Goodyear Chemical Company, Akron, OH); Nenoff, Tina Maria; Kartin, Mutlu; Johnson, Kaylynn (Goodyear Chemical Company, Akron, OH); Falconer, John; Noble, Richard

    2006-11-01

    We present synthesis, characterization and testing results of our applied research project, which focuses on the effects of surface and skeletal modification of zeolites for significant enhancements in current hydrocarbon (HC) separations. Zeolites are commonly used by the chemical and petroleum industries as catalysts and ion-exchangers. They have high potential for separations owing to their unique pore structures and adsorption properties and their thermal, mechanical and chemical properties. Because of zeolites separation properties, low cost, and robustness in industrial process, they are natural choice for use as industrial adsorbents. This is a multidisciplinary effort to research, design, develop, engineer, and test new and improved materials for the separation of branched vs. linear organic molecules found in commercially important HC streams via adsorption based separations. The focus of this project was the surface and framework modification of the commercially available zeolites, while tuning the adsorption properties and the selectivities of the bulk and membrane separations. In particular, we are interested with our partners at Goodyear Chemical, on how to apply the modified zeolites to feedstock isoprene purification. For the characterization and the property measurements of the new and improved materials powder X-ray diffraction (PXRD), Residual Gas Analyzer-Mass Spectroscopy (RGA-MS), Electron Microscopy (SEM/EDAX), temperature programmed desorption (TPD) and surface area techniques were utilized. In-situ carbonization of MFI zeolite membranes allowed for the maximum separation of isoprene from n-pentane, with a 4.1% enrichment of the binary stream with n-pentane. In four component streams, a modified MFI membrane had high selectivities for n-pentane and 1-3-pentadiene over isoprene but virtually no separation for the 2-methyl-2-butene/isoprene pair.

  7. Volatile organic compound adsorption on a nonporous silica surface: how do different probe molecules sense the same surface?

    PubMed

    Herdes, Carmelo; Carrott, M Manuela L Ribeiro; Russo, Patrícia A; Carrott, Peter J M

    2011-12-20

    In this work, we compare experimental results to molecular simulation results of volatile organic compound (VOC) adsorption on nonporous silica. We adopted an effective model for the rough solid surface, obtained by a temperature annealing scheme, plus an experimental/simulation nitrogen adsorption tuning process over the silica energetic oxygen parameter. The measurement/prediction of selected VOCs, specifically, n-pentane and methylcyclohexane, is presented in terms of adsorption isotherms, with an emphasis on the angle distribution analysis of the three studied probe molecules with respect to the same modeled surface. PMID:22060183

  8. Recent Advances In Science Support For Isolated Droplet Combustion Experiments

    NASA Technical Reports Server (NTRS)

    Dryer, F. L.; Kazakov, A.; Urban, B. D.; Kroenlein, K.

    2003-01-01

    In a joint program involving Prof. F.A. Williams of the University of California, San Diego and Dr. V. Nayagam of the National Center for Microgravity Research, the combustion characteristics of isolated liquid fuel droplets of n-heptane, n-decane, methanol, methanol-water, ethanol and ethanol-water having initial diameters between about 1 mm and 6 mm continues to be investigated. The objectives of the work are to improve fundamental knowledge of droplet combustion dynamics for pure fuels and fuel-water mixtures through microgravity experiments and theoretical analyses. The Princeton contributions support the engineering design, data analysis, and data interpretation requirements for the study of initially single component, spherically symmetric, isolated droplet combustion studies through experiments and numerical modeling. UCSD contributions are described in a companion communication in this conference. The Princeton effort also addresses the analyses of Fiber Supported Droplet Combustion (FSDC) experiments conducted with the above fuels and collaborative work with others who are investigating droplet combustion in the presence of steady convection. A thorough interpretation of droplet burning behavior for n-heptane and n-decane over a relatively wide range of conditions also involves the influences of sooting on the combustion behavior, and this particular aspect on isolated burning of droplets is under consideration in a collaborative program underway with Drexel University. This collaboration is addressed in another communication at this conference. The one-dimensional, time-dependent, numerical modeling approach that we have continued to evolve for analyzing isolated, quiescent droplet combustion data has been further applied to investigate several facets of isolated droplet burning of simple alcohols, n-heptane, and n-decane. Some of the new results are described below.

  9. Theoretical study of binding and permeation of ether-based polymers through interfaces.

    PubMed

    Samanta, Susruta; Hezaveh, Samira; Roccatano, Danilo

    2013-11-27

    We present a molecular dynamics simulation study on the interactions of poly(ethylene oxide) (PEO), poly(propylene oxide) (PPO), and their ABA-type block copolymer, poloxamers, at water/n-heptane and 1,2-dimyristoyl-sn-glycero-3-phospatidycholine (DMPC) lipid bilayer/water interfaces. The partition coefficients in water/1-octanol of the linear polyethers up to three monomers were calculated. The partition coefficients evidenced a higher hydrophobicity of the PPO in comparison to PEO. At the water/n-heptane interface, the polymers tend to adopt elongated conformations in agreement with similar experimental ellipsometry studies of different poloxamers. In the case of the poloxamers at the n-heptane/water interface, the stronger preference of the PPO block for the hydrophobic phase resulted in bottle-brush-type polymer conformations. At lipid bilayer/water interface, the PEO polymers, as expected from their hydrophilic nature, are weakly adsorbed on the surface of the lipid bilayer and locate in the water phase close to the headgroups. The free energy barriers of permeation calculated for short polymer chains suggest a thermodynamics propensity for the water phase that increase with the chain length. The lower affinity of PEO for the hydrophobic interior of the lipid bilayer resulted in the spontaneous expulsion within the simulation time. On the contrary, PPO chains and poloxamers have a longer residence time inside the bilayer, and they tend to concentrate in the tail region of the bilayer near the polar headgroups. In addition, polymers with PPO unit length comparable to the thickness of the hydrophobic region of the bilayer tend to span across the bilayer. PMID:24219592

  10. Structure and dynamics of 1,2-dimethoxyethane and 1,2-dimethoxypropane in aqueous and non-aqueous solutions: A molecular dynamics study

    NASA Astrophysics Data System (ADS)

    Hezaveh, Samira; Samanta, Susruta; Milano, Giuseppe; Roccatano, Danilo

    2011-10-01

    Herein, we report a comparative modelling study of 1,2-dimethoxyethane (DME) and 1,2-dimethoxypropane (DMP) at 298 K and 318 K in the liquid state, water mixtures, and at infinite dilution condition in water, methanol, carbon tetrachloride, and n-heptane. Both DME and DMP are united-atom models compatible with GROMOS/OPLS force fields. Calculated thermodynamic and structural properties of the pure DME and DMP liquids resulted in excellent agreement with the experimental data. In aqueous solutions, densities, diffusion coefficients, and concentration dependent conformers of DME, were in agreement with experimental data. The calculated free energy of solvation (?Ghyd) at 298 K is equal to -22.1 ± 0.8 kJ mol-1 in good agreement with the experimental value of 20.2 kJ mol-1. In addition, the free energy of solvation of DME in non-aqueous solvents follows the trend methanol ? water < carbon tetrachloride < n-heptane, consistently with the dielectric constant of the solvents. On contrary, the presence of an extra methyl group on chiral carbon makes DMP less soluble than DME in water (?Ghyd = -16.0 ± 1.1 kJ mol-1) but more soluble in non-polar solvents as n-heptane. Finally, for the DMP the chiral discrimination of the two enantiomers was calculated as solvation free energy difference of one DMP isomer in the solution of the other. The obtained value of ??GRS = -3.7 ± 1.4 kJ mol-1 indicates a net chiral discrimination of the two enantiomers.

  11. Structure and dynamics of 1,2-dimethoxyethane and 1,2-dimethoxypropane in aqueous and non-aqueous solutions: a molecular dynamics study.

    PubMed

    Hezaveh, Samira; Samanta, Susruta; Milano, Giuseppe; Roccatano, Danilo

    2011-10-28

    Herein, we report a comparative modelling study of 1,2-dimethoxyethane (DME) and 1,2-dimethoxypropane (DMP) at 298 K and 318 K in the liquid state, water mixtures, and at infinite dilution condition in water, methanol, carbon tetrachloride, and n-heptane. Both DME and DMP are united-atom models compatible with GROMOS?OPLS force fields. Calculated thermodynamic and structural properties of the pure DME and DMP liquids resulted in excellent agreement with the experimental data. In aqueous solutions, densities, diffusion coefficients, and concentration dependent conformers of DME, were in agreement with experimental data. The calculated free energy of solvation (?G(hyd)) at 298 K is equal to -22.1 ± 0.8 kJ mol(-1) in good agreement with the experimental value of 20.2 kJ mol(-1). In addition, the free energy of solvation of DME in non-aqueous solvents follows the trend methanol ? water < carbon tetrachloride < n-heptane, consistently with the dielectric constant of the solvents. On contrary, the presence of an extra methyl group on chiral carbon makes DMP less soluble than DME in water (?G(hyd) = -16.0 ± 1.1 kJ mol(-1)) but more soluble in non-polar solvents as n-heptane. Finally, for the DMP the chiral discrimination of the two enantiomers was calculated as solvation free energy difference of one DMP isomer in the solution of the other. The obtained value of ??G(RS) = -3.7 ± 1.4 kJ mol(-1) indicates a net chiral discrimination of the two enantiomers. PMID:22047246

  12. Kinetic modelling of a surrogate diesel fuel applied to 3D auto-ignition in HCCI engines

    E-print Network

    Bounaceur, Roda; Fournet, René; Battin-Leclerc, Frédérique; Jay, S; Da Cruz, A Pires

    2007-01-01

    The prediction of auto-ignition delay times in HCCI engines has risen interest on detailed chemical models. This paper described a validated kinetic mechanism for the oxidation of a model Diesel fuel (n-decane and ?-methylnaphthalene). The 3D model for the description of low and high temperature auto-ignition in engines is presented. The behavior of the model fuel is compared with that of n-heptane. Simulations show that the 3D model coupled with the kinetic mechanism can reproduce experimental HCCI and Diesel engine results and that the correct modeling of auto-ignition in the cool flame region is essential in HCCI conditions.

  13. Syngas production from heavy liquid fuel reforming in inert porous media

    E-print Network

    Pastore, Andrea

    2010-11-16

    among all the fuels tested. List of Publications Two journal papers and two conference papers have been published about the results described in this thesis: • A. Pastore and E. Mastorakos. “Rich n-heptane and Diesel Com- bustion in Porous Media... ”, Experimental Thermal and Fluid Sci- ence, 34:359-365, 2010. • A. Pastore and E. Mastorakos. “Syngas Production from Liquid Fuels in a Non-Catalytic Porous Burner”, Fuel, Article in Press, 2010. • A. Pastore and E. Mastorakos. “Syngas Production from Diesel Non...

  14. Detection of drugs in human hair for clinical and forensic applications.

    PubMed

    Kintz, P; Tracqui, A; Mangin, P

    1992-01-01

    While hair has for sometime been analyzed for assessment of trace elements, it is only in recent years that attention has been focused on this matrix as a possible means of evaluating drug impregnation. This technique was applied to treated subjects and drug abusers for determination of drug consumation. The method involved decontamination in ethanol, solubilization in sodium hydroxide at 100 degrees C for 10 min, extraction in chloroform/isopropanol/n-heptane (50:17:33, v/v), separation on a BP-5 capillary column (GC) and detection by mass spectrometry. Hair samples were analysed for barbiturates, antidepressants, benzodiazepines, beta-blockers, nicotine, opiates, benzoylecgonine, cannabis and amphetamines. PMID:1503993

  15. Long Duration Exposure Facility (LDEF) low-temperature Heat Pipe Experiment Package (HEPP)

    NASA Astrophysics Data System (ADS)

    McIntosh, Roy; Brennan, Patrick J.

    1991-06-01

    The flight test results are discussed obtained with the Heat Pipe Experiment Package (HEPP). The HEPP was designed to demonstrate the performance of an ethane constant conductance heat pipe (CCHP) and an ethane heat pipe diode in microgravity. These heat pipes have a nominal operating temperature range of 140 to 250 K. Also, included in the HEPP is a Phase Change Material (PCM) canister which provides temperature stability through melting and freezing of the n-heptane PCM. A comparison of pre-flight, flight, and post-flight thermal performance is also presented.

  16. Heavy-atom enhancement and analytical figures of merit for low-temperature phosphorimetry in the red region for several polynuclear aromatic hydrocarbons.

    PubMed

    Inman, E L; Jurgensen, A; Winefordner, J D

    1982-05-01

    Analytical figures of merit for the low-temperature (77 K) phosphorescence of 22 polynuclear aromatic hydrocarbons are presented. Also, heavy-atom enhancement factors have been obtained for these compounds with an n-heptane solvent with iodoethane and dimethylmercury as sources of external heavy atoms, and with a 3:1 v/v ethanol/water solvent with potassium iodide, silver nitrate, thallium acetate, and lead acetate as heavy-atom sources. Effects of these heavy atoms on the phosphorescence signals vary markedly, depending on the compound of interest. PMID:18963154

  17. CONTROL OF LASER RADIATION PARAMETERS: Efficient 510 ? 578-nm conversion of emission of copper vapour lasers

    NASA Astrophysics Data System (ADS)

    D'yachkov, Aleksei B.; Labozin, Valerii P.

    2002-09-01

    The results of experiments on the 510 ? 578-nm conversion of high-power radiation from a copper vapour laser (CVL) in a dye cell are presented. The use of the efficient laser dye Pyrromethane 597 (PM-597) made it possible to convert the 120-W CVL radiation (72 W at 510 nm + 48 W at 578 nm) into 102-W radiation at 578 nm, which is equivalent to a conversion efficiency of 85%. Photostability of the dye in various solvents is studied. The photostability (more than 45 GJ mole-1) of PM-597 in n-heptane is found to be higher than that of Rh 6G in ethanol.

  18. Photolytic cage effect and atom recombination of iodine in compressed gases and liquids: Experiments and simple models

    NASA Astrophysics Data System (ADS)

    Otto, B.; Schroeder, J.; Troe, J.

    1984-07-01

    Quantum yields for photolysis of molecular iodine and recombination rate coefficients of iodine atoms were measured by nanosecond laser flash photolysis in the liquid solvents CO2, C2H6, C3H8, and n-heptane at pressures up to 5 kbar. The experiments continue earlier studies with these solvents performed in the gas phase at high pressures. The results are represented in terms of simple models which involve cage breakout, cage energy relaxation, stabilization in clusters, and diffusion control. Experimental studies over wide density ranges allow for a separation of the various components of the mechanism.

  19. Migration of Irganox 1010 from ethylene-vinyl acetate films to foods and food-simulating liquids.

    PubMed

    Schwope, A D; Till, D E; Ehntholt, D J; Sidman, K R; Whelan, R H; Schwartz, P S; Reid, R C

    1987-04-01

    In a series of experiments on the migration of the antioxidant Irganox 1010 from ethylene-vinyl acetate (EVA) films into food-simulating liquids and foods, the antioxidant was found to migrate rapidly from EVA film into n-heptane, 100% ethanol and corn oil. The rate of migration into these media was greater from EVA than from low-density polyethylene (LDPE) under comparable conditions. In contrast, little migration of Irganox 1010 was recorded on exposure of the EVA film to aqueous media, whereas migration from LDPE into such media was relatively high. PMID:3583159

  20. Fluorimetric determination of levoprotiline in human plasma after thin-layer chromatographic or high performance liquid chromatographic separation.

    PubMed

    Horne, C; Spahn, H; Mutschler, E

    1987-10-01

    The quantitative determination of the new antidepressant drug levoprotiline, the R-(-)-enantiomer of oxa-protiline (a-[methylamino)methyl)-9,10-ethanoanthracene-9(10H)-ethanol), in human biological material is described. Analysis is performed by alkaline extraction with n-heptane-isopropanol, subsequent fluorescence derivatisation with NBD chloride (4-chloro-7-nitrobenzofurazan), thin layer or high performance liquid chromatography, and fluorimetric measurement of the derivatisation product (lambda max ex. = 470 nm, lambda max em. = 525 nm). The sensitivity of the procedure (detection limit less than 1 ng/ml) permits the performance of pharmacokinetic studies after therapeutic doses. PMID:3435591

  1. The effect of initial diameter in sperically symmetric droplet combustion of sooting fuels

    NASA Technical Reports Server (NTRS)

    Jackson, G. S.; Avedisian, C. T.

    1994-01-01

    The effect of initial droplet diameter on the burning rate of sooting fuels - n-heptane and 1-chloro-octane - was examined experimentally at low gravity. A 1.2s drop tower provided a low gravity environment to minimize buoyancy and achieve spherically symmetric flames for stationary droplets. Free-floating and fiber-supported droplets were burned, and both techniques gave matching results for droplets of similar initial diameter. Burning rate constants for both fuels were measured for a large number of droplets ranging from 0.4 to 1.1mm in initial diameter.

  2. Testing of high-octane fuels in the single-cylinder airplane engine

    NASA Technical Reports Server (NTRS)

    Seeber, Fritz

    1940-01-01

    One of the most important properties of aviation fuels for spark-ignition engines is their knock rating. The CFR engine tests of fuels of 87 octane and above does not always correspond entirely to the actual behavior of these fuels in the airplane engine. A method is therefore developed which, in contrast to the octane number determination, permits a testing of the fuel under various temperatures and fuel mixture conditions. The following reference fuels were employed: 1) Primary fuels; isooctane and n-heptane; 2) Secondary fuels; pure benzene and synthetic benzine.

  3. Low and intermediate temperature oxidation of ethanol and ethanol-PRF blends: An experimental and modeling study

    SciTech Connect

    Haas, Francis M.; Chaos, Marcos; Dryer, Frederick L.

    2009-12-15

    In this brief communication, we present new experimental species profile measurements for the low and intermediate temperature oxidation of ethanol under knock-prone conditions. These experiments show that ethanol exhibits no global low temperature reactivity at these conditions, although we note the heterogeneous decomposition of ethanol to ethylene and water. Similar behavior is reported for an E85 blend in n-heptane. Kinetic modeling results are presented to complement these experiments and elucidate the interaction of ethanol and primary reference fuels undergoing cooxidation. (author)

  4. Velocity profiles in laminar diffusion flames

    NASA Technical Reports Server (NTRS)

    Lyons, Valerie J.; Margle, Janice M.

    1986-01-01

    Velocity profiles in vertical laminar diffusion flames were measured by using laser Doppler velocimetry (LDV). Four fuels were used: n-heptane, iso-octane, cyclohexane, and ethyl alcohol. The velocity profiles were similar for all the fuels, although there were some differences in the peak velocities. The data compared favorably with the theoretical velocity predictions. The differences could be attributed to errors in experimental positioning and in the prediction of temperature profiles. Error in the predicted temperature profiles are probably due to the difficulty in predicting the radiative heat losses from the flame.

  5. Premixed ignition behavior of alternative diesel fuel-relevant compounds in a motored engine experiment

    SciTech Connect

    Szybist, James P.; Boehman, Andre L.; Haworth, Daniel C.; Koga, Hibiki

    2007-04-15

    A motored engine study using premixed charges of fuel and air at a wide range of diesel-relevant equivalence ratios was performed to investigate autoignition differences among surrogates for conventional diesel fuel, gas-to-liquid (GTL) diesel fuel, and biodiesel, as well as n-heptane. Experiments were performed by delivering a premixed charge of vaporized fuel and air and increasing the compression ratio in a stepwise manner to increase the extent of reaction while monitoring the exhaust composition via Fourier transform infrared (FTIR) spectrometry and collecting condensable exhaust gas for subsequent gas chromatography/mass spectrometry (GC/MS) analysis. Each fuel demonstrated a two-stage ignition process, with a low-temperature heat release (LTHR) event followed by the main combustion, or high-temperature heat release (HTHR). Among the three diesel-relevant fuels, the magnitude of LTHR was highest for GTL diesel, followed by methyl decanoate, and conventional diesel fuel last. FTIR analysis of the exhaust for n-heptane, the conventional diesel surrogate, and the GTL diesel surrogate revealed that LTHR produces high concentrations of aldehydes and CO while producing only negligible amounts of CO{sub 2}. Methyl decanoate differed from the other two-stage ignition fuels only in that there were significant amounts of CO{sub 2} produced during LTHR; this was the result of decarboxylation of the ester group, not the result of oxidation. GC/MS analysis of LTHR exhaust condensate for n-heptane revealed high concentrations of 2,5-heptanedione, a di-ketone that can be closely tied to species in existing autoignition models for n-heptane. GC/MS analysis of the LTHR condensate for conventional diesel fuel and GTL diesel fuel revealed a series of high molecular weight aldehydes and ketones, which were expected, as well as a series of organic acids, which are not commonly reported as products of combustion. The GC/MS analysis of the methyl decanoate exhaust condensate revealed that the aliphatic chain acts similarly to n-paraffins during LTHR, while the ester group remains intact. Thus, although the FTIR data revealed that decarboxylation occurs at significant levels for methyl decanoate, it was concluded that this occurs after the aliphatic chain has been largely consumed by other LTHR reactions. (author)

  6. The role of water in the formation of reversed micelles: An antimicellization agent

    USGS Publications Warehouse

    Yu, Z.-J.; Zhou, N.-F.; Neuman, R.D.

    1992-01-01

    Micellization of sodium bis(2-ethylhexyl) phosphate in n-heptane has been studied under controlled environmental conditions by dynamic and static light scattering. The results clearly show that a trace amount of water has a very dramatic effect on reversed micellization. In contrast with results in the literature, water can function as an antimicellization agent. The generality of and the evidence for supporting the current view that water is a prerequisite for the formation of reversed micelles are discussed and criticized. ?? 1992 American Chemical Society.

  7. Removal of dilute volatile organic contaminants from gaseous waste streams using trickling biofilters

    SciTech Connect

    Barton, J.W.; Klasson, K.T.; Koran, L.J. Jr.

    1995-12-31

    As increasingly stringent environmental regulations and oversight force emission reduction, dilute gaseous hydrocarbon waste streams remain the focus of remediation efforts for many industries. Advances in biotechnology hold promise for providing low-cost alternatives to more traditional, energy intensive treatment methods such as incineration and adsorption. Elucidation of engineering principles governing the behavior of such systems, combined with successful predictive modeling, will broaden their applicability. Oak Ridge National Laboratory has developed processes which exploit a microbial consortium to treat a mixture of 0.5% n-pentane and 0.5% isobutane in air. Since hydrocarbon gases are sparingly soluble in water, good mixing and high surface area between the gas and liquid phases are essential properties for biodegradation to be effective. A trickle-bed bioreactor (or trickling biofilter) has been operated continuously using n-pentane and isobutane as sole carbon and energy sources for over fifteen months to provide a high surface area (using a structured packing) with increased rates. Maximum degradation rates achieved thus far have been {approximately}60 g VOC/h/m{sup 3} in a single pass in this gas-continuous columnar system. Mass transfer coefficients comparable to literature values have also been measured for this reactor, with values being two to three times higher than those found in gas-recycle reactors.

  8. Coupled-cluster, Möller Plesset (MP2), density fitted local MP2, and density functional theory examination of the energetic and structural features of hydrophobic solvation: Water and pentane

    NASA Astrophysics Data System (ADS)

    Ghadar, Yasaman; Clark, Aurora E.

    2012-02-01

    The interaction potentials between immiscible polar and non-polar solvents are a major driving force behind the formation of liquid:liquid interfaces. In this work, the interaction energy of water-pentane dimer has been determined using coupled-cluster theory with single double (triple) excitations [CCSD(T)], 2nd order Möller Plesset perturbation theory (MP2), density fitted local MP2 (DF-LMP2), as well as density functional theory using a wide variety of density functionals and several different basis sets. The M05-2X exchange correlation functionals exhibit excellent agreement with CCSD(T) and DF-LMP2 after taking into account basis set superposition error. The gas phase water-pentane interaction energy is found to be quite sensitive to the specific pentane isomer (2,2-dimethylpropane vs. n-pentane) and relative orientation of the monomeric constituents. Subsequent solution phase cluster calculations of 2,2-dimethylpropane and n-pentane solvated by water indicate a positive free energy of solvation that is in good agreement with available experimental data. Structural parameters are quite sensitive to the density functional employed and reflect differences in the two-body interaction energy calculated by each method. In contrast, cluster calculations of pentane solvation of H2O solute are found to be inadequate for describing the organic solvent, likely due to limitations associated with the functionals employed (B3LYP, BHandH, and M05-2X).

  9. Evaluation of a locally homogeneous flow model of spray combustion

    NASA Technical Reports Server (NTRS)

    Mao, C. P.; Szekely, G. A., Jr.; Faeth, G. M.

    1980-01-01

    A model of spray combustion which employs a second-order turbulence model was developed. The assumption of locally homogeneous flow is made, implying infinitely fast transport rates between the phase. Measurements to test the model were completed for a gaseous n-propane flame and an air atomized n-pentane spray flame, burning in stagnant air at atmospheric pressure. Profiles of mean velocity and temperature, as well as velocity fluctuations and Reynolds stress, were measured in the flames. The predictions for the gas flame were in excellent agreement with the measurements. The predictions for the spray were qualitatively correct, but effects of finite rate interphase transport were evident, resulting in a overstimation of the rate development of the flow. Predictions of spray penetration length at high pressures, including supercritical combustion conditions, were also completed for comparison with earlier measurements. Test conditions involved a pressure atomized n-pentane spray, burning in stagnant air at pressures of 3, 5, and 9 MPa. The comparison between predictions and measurements was fair. This is not a very sensitive test of the model, however, and further high pressure experimental and theoretical results are needed before a satisfactory assessment of the locally homogeneous flow approximation can be made.

  10. Effects of Malva sylvestris and Its Isolated Polysaccharide on Experimental Ulcerative Colitis in Rats.

    PubMed

    Hamedi, Azadeh; Rezaei, Hossein; Azarpira, Negar; Jafarpour, Mehrnaz; Ahmadi, Fatemeh

    2016-01-01

    Malva sylvestris is an edible plant that is consumed as a herbal supplement for its antiulcer and colon cleansing properties in traditional Persian medicine. This study was designed to evaluate its effects on ulcerative colitis, which is a chronic gastrointestinal inflammation. Colitis was induced by rectal instillation of acetic acid solution. Rats in different groups received aqueous, n-hexane, or ethanolic fractions of the plant before induction of colitis. Isolated polysaccharide of plant was also tested in 2 groups before and after induction of colitis. Macroscopic and microscopic evaluation of colitis showed that the aqueous fraction was very effective in preventing the inflammation and efficacy was lower for ethanolic and n-hexane fractions. Polysaccharide was effective in reducing signs of inflammation, especially as pretreatment. These beneficial effects provide evidences that this plant can be suggested for patients with this disease to improve their health condition or to reduce adverse effects of their medication. PMID:26045553

  11. Antimicrobial and toxicological studies of Ochthochloa compressa plant.

    PubMed

    Ahmad, Saeed; Bashir, Muhammad Tayyab; Khaliq, Farhan Hameed; Mannan, Abdul; Mukhtar, Muhammad Fahad

    2014-09-01

    The present study demonstrates the biological activity of Ochthochloa compressa, since extensive literature survey has shown no documented biological activity of this plant. Ethanolic extract of whole plant was prepared and evaporated under reduced pressure by rota vapor. The crude extract was further fractionated into n-hexane, dichloromethane, ethyl acetate and n-butanol soluble fractions. These fractions were screened for antifungal, phytotoxic, cytotoxic and antibacterial activities. Dichloromethane soluble fraction showed significant phytotoxicity whereas n-hexane, ethyl acetate, and n-butanol soluble fractions showed non-significant phytotoxicity. Similarly, ethyl acetate soluble fraction was the only fraction, which showed significant cytotoxic activity. There was no antibacterial but moderate antifungal activity was shown by these fractions against selected strains of bacteria and fungi. This is the first report on the biological activity of O. compressa. PMID:25176377

  12. Biodiesel production by direct transesterification of microalgal biomass with co-solvent.

    PubMed

    Zhang, Yan; Li, Ya; Zhang, Xu; Tan, Tianwei

    2015-11-01

    In this study, a direct transesterification process using 75% ethanol and co-solvent was studied to reduce the energy consumption of lipid extraction process and improve the conversion yield of the microalgae biodiesel. The addition of a certain amount of co-solvent (n-hexane is most preferable) was required for the direct transesterification of microalgae biomass. With the optimal reaction condition of n-hexane to 75% ethanol volume ratio 1:2, mixed solvent dosage 6.0mL, reaction temperature 90°C, reaction time 2.0h and catalyst volume 0.6mL, the direct transesterification process of microalgal biomass resulted in a high conversion yield up to 90.02±0.55wt.%. PMID:26232317

  13. Determination of the chromatic dispersion of liquids based on the liquid-prism SPR configuration in angular and spectral interrogations

    NASA Astrophysics Data System (ADS)

    Lan, Guoqiang; Liu, Shugang; Wang, Yuxiao; Zhang, Xueru; Song, Yinglin

    2015-10-01

    In this work, we use the liquid-prism SPR sensing configuration to determine the chromatic dispersion of different liquids, since the condition of SPR is sensitive to the refractive index of the liquid prism. We use the glass slide coated with 50 nm Au film as the sensing chip, and use AvaLight - HAL (360 nm - 2500 nm) light source as the broaden band light source in our experiments. We adopt the deionized water as the standard sample to determine the chromatic dispersion of different liquid samples (ethanol and n-hexane), and we implement the experiment through the SPR sensing configuration in angular and spectral interrogations. According to the experimental data, the chromatic dispersions of ethanol and n-hexane are obtained. The proposed technique provides a new high sensitive method for the determination of chromatic dispersion of liquids.

  14. Magic-angle-spinning NMR studies of acid sites in zeolite H-ZSM-5

    SciTech Connect

    Brunner, E.; Ernst, H.; Freude, D.; Froehlich, T.; Hunger, M.; Pfeifer, H. )

    1991-01-01

    {sup 1}H, {sup 13}C, {sup 27}Al, and {sup 29}Si magic-angle-spinning (MAS) NMR was used to elucidate the nature of the catalytic activity of zeolite H-ZSM-5. {sup 1}H MAS NMR of sealed samples after mild hydrothermal dealumination shows that the enhanced activity for n-hexane cracking is not due to an enhanced Bronstead acidity. The concentrations of the various OH groups and aluminous species suggest that the reason for the enhanced catalytic activity is the interaction of the n-hexane molecule with a bridging hydroxyl group and with extra-framework aluminium species, which give rise to the enhanced activity, cannot be easily removed from their positions, and are therefore immobilized by the zeolitic framework.

  15. Adsorption of selected volatile organic vapors on multiwall carbon nanotubes.

    PubMed

    Shih, Yang-hsin; Li, Mei-syue

    2008-06-15

    Carbon nanotubes are expected to play an important role in sensing, pollution treatment and separation techniques. This study examines the adsorption behaviors of volatile organic compounds (VOCs), n-hexane, benzene, trichloroethylene and acetone on two multiwall carbon nanotubes (MWCNTs), CNT1 and CNT2. Among these VOCs, acetone exhibits the highest adsorption capacity. The highest adsorption enthalpies and desorption energies of acetone were also observed. The strong chemical interactions between acetone and both MWCNTs may be the result from chemisorption on the topological defects. The adsorption heats of trichloroethylene, benzene, and n-hexane are indicative of physisorption on the surfaces of both MWCNTs. CNT2 presents a higher adsorption capacity than CNT1 due to the existence of an exterior amorphous carbon layer on CNT2. The amorphous carbon enhances the adsorption capacity of organic chemicals on carbon nanotubes. The morphological and structure order of carbon nanotubes are the primary affects on the adsorption process of organic chemicals. PMID:17980962

  16. Green procedure with a green solvent for fats and oils' determination. Microwave-integrated Soxhlet using limonene followed by microwave Clevenger distillation.

    PubMed

    Virot, Matthieu; Tomao, Valérie; Ginies, Christian; Visinoni, Franco; Chemat, Farid

    2008-07-01

    Here is described a green and original alternative procedure for fats and oils' determination in oleaginous seeds. Extractions were carried out using a by-product of the citrus industry as extraction solvent, namely d-limonene, instead of hazardous petroleum solvents such as n-hexane. The described method is achieved in two steps using microwave energy: at first, extractions are attained using microwave-integrated Soxhlet, followed by the elimination of the solvent from the medium using a microwave Clevenger distillation in the second step. Oils extracted from olive seeds were compared with both conventional Soxhlet and microwave-integrated Soxhlet extraction procedures performed with n-hexane in terms of qualitative and quantitative determination. No significant difference was obtained between each extract allowing us to conclude that the proposed method is effective and valuable. PMID:18471820

  17. Release of volatile mercury from vascular plants

    NASA Technical Reports Server (NTRS)

    Siegel, S. M.; Puerner, N. J.; Speitel, T. W.

    1974-01-01

    Volatile, organic solvent soluble mercury has been found in leaves and seeds of several angiosperms. Leaves of garlic vine, avocado, and haole-koa release mercury in volatile form rapidly at room temperature. In garlic vine, the most active release is temperature dependent, but does not parallel the vapor-pressure temperature relationship for mercury. Mercury can be trapped in nitric-perchloric acid digestion fluid, or n-hexane, but is lost from the hexane unless the acid mixture is present. Seeds of haole-koa also contain extractable mercury but volatility declines in the series n-hexane (90%), methanol (50%), water (10%). This suggests that reduced volatility may accompany solvolysis in the more polar media.

  18. [Determination of buprofezin, methamidophos, acephate, and triazophos residues in Chinese tea samples by gas chromatography].

    PubMed

    Zhang, Shuiba; Yi, Jun; Ye, Jianglei; Zheng, Wenhui; Cai, Xueqin; Gong, Zhenbin

    2004-03-01

    A method has been developed for the simultaneous determination of buprofezin, methamidophos, acephate and triazophos residues in Chinese tea samples. The pesticide residues were extracted from tea samples with a mixture of ethyl acetate and n-hexane (50:50, v/v) at 45 degrees C. The extracts were subsequently treated with a column packed with 40 mg of active carbon by gradient elution with ethyl acetate and n-hexane. Buprofenzin and the three organophosphorus pesticides were analyzed by gas chromatography using a DB-210 capillary column and a nitrogen-phosphorus detector. The recoveries for spiked standards were 73.4%-96.9%. The relative standard deviations were all within 4.63%. The limits of quantitation (3sigma) in the tea samples were about 7.0-12.0 microg/kg. PMID:15712876

  19. ?-Glucosidase inhibitory activities of fatty acids purified from the internal organ of sea cucumber Stichopus japonicas.

    PubMed

    Nguyen, T H; Kim, S M

    2015-04-01

    ?-Glucosidase inhibitory activities of the various solvent fractions (n-hexane, CHCl3 , EtOAc, BuOH, and water) of sea cucumber internal organ were investigated. 1,3-Dipalmitolein (1) and cis-9-octadecenoic acid (2) with potent ?-glucosidase inhibitory activity were purified from the n-hexane fraction of sea cucumber internal organ. IC50 values of compounds 1 and 2 were 4.45 and 14.87 ?M against Saccharomyces cerevisiae ?-glucosidase. These compounds mildly inhibited rat-intestinal ?-glucosidase. In addition, both compounds showed a mixed competitive inhibition against S. cerevisiae ?-glucosidase and were very stable at pH 2 up to 60 min. The KI values of compounds 1 and 2 were 0.48 and 1.24 ?M, respectively. Therefore, the internal organ of sea cucumber might be a potential new source of ?-glucosidase inhibitors suitably used for prevention of obesity and diabetes mellitus. PMID:25735900

  20. Viscosity of binary mixtures. IV. Triethylamine with alkanes and monoalkylamines at 303.15 and 313.15 K

    NASA Astrophysics Data System (ADS)

    Oswal, S. L.; Patel, S. G.

    1992-09-01

    Viscosities and densities of seven binary mixtures of n-hexane, n-octane, isooctane, n-propylamine, n-butylamine, n-hexylamine, and n-octylamine with triethylamine have been measured at 303.15 and 313.15 K. Deviations of viscosities from a linear dependence on the mole fraction and values of excess Gibbs energy of activation ?G *E of viscous flow are attributable to the H-bonding and to the size of the alkylamine and alkane molecules.

  1. A chemical extraction method for mimicking bioavailability of polycyclic aromatic hydrocarbons to wheat grown in soils containing various amounts of organic matter

    SciTech Connect

    Shu Tao; Fuliu Xu; Wenxin Liu; Yanhong Cui; Raymond M. Coveney, Jr.

    2006-04-01

    Severe contamination of agricultural soils by polycyclic aromatic hydrocarbons (PAHs) occurs in many places in China mainly as a result of coal and biomass combustion. Because ingestion is the main source of human exposure to PAHs and vegetables are basic ingredients for the Chinese diet, it is important to know how and to what extent PAHs are accumulated in vegetables produced in contaminated soils. This study, evaluated the extent to which organic matter contents in soils influence the accumulation of PAHs by the roots of wheat plants and have developed a rapid chemical method for determining the bioavailability of PAH. Four PAHs, naphthalene, acenaphthylene, fluorene, and phenanthrene, were added to natural soil samples with different amounts of organic matter for pot experiments to evaluate apparent bioavailability of PAHs to wheat roots (Triticum aestivum L.). The extractabilities of PAHs in the soil were tested by a sequential extraction scheme using accelerated solvent extraction with water, n-hexane, and a mixture of dichloromethane and acetone as solvents. The water or n-hexane-extractable PAHs were positively correlated to dissolved organic matter (DOM) and negatively correlated to total organic matter (TOM), indicating mobilization and immobilization effects of DOM and TOM on soil PAHs, respectively. The apparent accumulation of PAHs by wheat roots was also positively and negatively correlated to DOM and TOM, respectively. As a result, there are positive correlations between the amounts of PAHs extracted by water or n-hexane and the quantities accumulated in plant roots, suggesting the feasibility of using water- or n-hexanes-extractable fractions as indicators of PAH availability to plants. 19 refs., 8 figs., 1 tab.

  2. Isochoric thermal conductivity of solid n-alkanes: Hexane C6H14

    NASA Astrophysics Data System (ADS)

    Konstantinov, V. A.; Revyakin, V. P.; Sagan, V. V.

    2011-05-01

    The isochoric thermal conductivity of solid n-hexane C6H14 is studied using three samples with different densities for temperatures ranging from 100 K to the onset of melting. In all cases, the isochoric thermal conductivity varies more weakly than ??1/T. The present results are compared with the thermal conductivities of other representatives of the n-alkanes. The contributions of low-frequency phonons and "diffuse modes" to the thermal conductivity are calculated.

  3. Influence of Crystal Expansion/Contraction on Zeolite Membrane Permeation

    SciTech Connect

    Sorenson, Stephanie G; Payzant, E Andrew; Noble, Richard D; Falconer, John L.

    2010-01-01

    X-ray diffraction was used to measure the unit cell parameters of B-ZSM-5, SAPO-34, and NaA zeolite powders as a function of adsorbate loading at 303 K, and in one case, at elevated temperatures. Most adsorbates expanded the zeolite crystals below saturation loading at 303 K: n-hexane and SF6 in B-ZSM-5, methanol and CO2 in SAPO-34, and methanol in NaA zeolite. As the loadings increased, the crystals expanded more. Changes in the unit cell volumes of B-ZSM-5 and SAPO-34 zeolite powders correlated with changes in permeation through zeolite membranes defects. When the zeolite crystals expanded or contracted upon adsorption, the defect sizes decreased or increased. In B-ZSM-5 membranes, the fluxes through defects decreased dramatically when n-hexane or SF6 adsorbed. In contrast, i-butane adsorption at 303 K contracted B-ZSM-5 crystals at low loadings and expanded them at higher loadings. Correspondingly, the flux through B-ZSM-5 membrane defects increased at low i-butane loadings and decreased at high loading because the defects increased in size at low loading and decreased at high loadings. At 398 K and 473 K, n-hexane expanded the B-ZSM-5 unit cell more as the temperature increased from 303 to 473 K. The silicalite-1 and B-ZSM-5 unit cell volumes expanded similarly upon n-hexane adsorption at 303 K; boron substitution had little effect on volume expansion.

  4. Adsorption of polychlorinated dibenzo-p-dioxins/dibenzofurans on activated carbon from hexane.

    PubMed

    Zhou, Xu-Jian; Buekens, Alfons; Li, Xiao-Dong; Ni, Ming-Jiang; Cen, Ke-Fa

    2016-02-01

    Activated carbon is widely used to abate dioxins and dioxin-like compounds from flue gas. Comparing commercial samples regarding their potential to adsorb dioxins may proceed by using test columns, yet it takes many measurements to characterise the retention and breakthrough of dioxins. In this study, commercial activated carbon samples are evaluated during tests to remove trace amounts of dioxins dissolved in n-hexane. The solution was prepared from fly ash collected from a municipal solid waste incinerator. The key variables selected were the concentration of dioxins in n-hexane and the dosage of activated carbon. Both polychlorinated dibenzo-p-dioxins (PCDDs) and polychlorinated dibenzofurans (PCDFs) showed very high removal efficiencies (94.7%-98.0% for PCDDs and 99.7%-99.8% for PCDFs). The presence of a large excess of n-hexane solvent had little effect on the removal efficiency of PCDD/Fs. The adsorbed PCDD/Fs showed a linear correlation (R(2) > 0.98) with the initial concentrations. Comparative analysis of adsorption isotherms showed that a linear Henry isotherm fitted better the experimental data (R(2) = 0.99 both for PCDDs and PCDFs) than the more usual Freundlich isotherm (R(2) = 0.88 for PCDDs and 0.77 for PCDFs). Finally, the results of fingerprint analysis indicated that dioxin fingerprint (weight proportion of different congeners) on activated carbon after adsorption did not change from that in hexane. PMID:26476048

  5. Ultrasound-assisted extraction and solid-phase extraction as a cleanup procedure for organochlorinated pesticides and polychlorinated biphenyls determination in aquatic samples by gas chromatography with electron capture detection.

    PubMed

    Sun, Xiumei; Hu, Hongmei; Zhong, Zhi; Jin, Yanjian; Zhang, Xiaojun; Guo, Yuanming

    2015-02-01

    The feasibility of developing a quick, easy, efficient procedure for the simultaneous determination of organochlorinated pesticides and polychlorinated biphenyls in aquatic samples using gas chromatography with electron capture detection based on solid-phase extraction was investigated. The extraction solvent (n-hexane/acetone, cyclohexane/ethyl acetate, n-hexane/dichloromethane, n-hexane) for ultrasound-assisted solid-liquid extraction and solid-phase extraction columns (florisil, neutral alumina, acidic alumina, aminopropyl trimethoxy silane, propyl ethylenediamine, aminopropyl trimethoxy silane/propyl ethylenediamine, graphitized carbon black and silica) for cleanup procedure were optimized. The gas chromatography with electron capture detection method was validated in terms of linearity, sensitivity, reproducibility, and recovery. Mean recoveries ranged from 75 to 115% with relative standard deviations <13%. Quantification limits were 0.20-0.40 ng/g for organochlorinated pesticides and polychlorinated biphenyls. The satisfactory data demonstrated the good reproducibility of the method with relative standard deviations lower than 13%. In comparison to other related methods, this method requires less time and solvent and allows for rapid isolation of the target analytes with high selectivity. This method therefore allows for the screening of numerous samples and can also be used for routine analyses. PMID:25529797

  6. Analysis of Benzo[a]pyrene in Vegetable Oils Using Molecularly Imprinted Solid Phase Extraction (MISPE) Coupled with Enzyme-Linked Immunosorbent Assay (ELISA)

    PubMed Central

    Pschenitza, Michael; Hackenberg, Rudolf; Niessner, Reinhard; Knopp, Dietmar

    2014-01-01

    This paper describes the development of a molecularly imprinted polymer-based solid phase extraction (MISPE) method coupled with enzyme-linked immunosorbent assay (ELISA) for determination of the PAH benzo[a]pyrene (B[a]P) in vegetable oils. Different molecularly imprinted polymers (MIPs) were prepared using non-covalent 4-vinylpyridine/divinylbenzene co-polymerization at different ratios and dichloromethane as porogen. Imprinting was done with a template mixture of phenanthrene and pyrene yielding a broad-specific polymer for PAHs with a maximum binding capacity (Q) of ?32 ?g B[a]P per 50 mg of polymer. The vegetable oil/n-hexane mixture (1:1, (v/v)) was pre-extracted with acetonitrile, the solvent evaporated, the residue reconstituted in n-hexane and subjected to MISPE. The successive washing with n-hexane and isopropanol revealed most suitable to remove lipid matrix constituents. After elution of bound PAHs from MISPE column with dichloromethane, the solvent was evaporated, the residue reconstituted with dimethyl sulfoxide and diluted 100-fold with methanol/water (10:90, (v/v)) for analysis of B[a]P equivalents with an ELISA. The B[a]P recovery rates in spiked vegetable oil samples of different fatty acid composition were determined between 63% and 114%. The presence of multiple PAHs in the oil sample, because of MIP selectivity and cross-reactivity of the ELISA, could yield overestimated B[a]P values. PMID:24887045

  7. Antimicrobial Activity and Brine Shrimp Lethality Bioassay of the Leaves Extract of Dillenia indica Linn.

    PubMed

    Apu, As; Muhit, Ma; Tareq, Sm; Pathan, Ah; Jamaluddin, Atm; Ahmed, M

    2010-01-01

    The crude methanolic extract of Dillenia indica Linn. (Dilleniaceae) leaves has been investigated for the evaluation of antimicrobial and cytotoxic activities. Organic solvent (n-hexane, carbon tetrachloride and chloroform) fractions of methanolic extract and methanolic fraction (aqueous) were screened for their antimicrobial activity by disc diffusion method. Besides, the fractions were screened for cytotoxic activity using brine shrimp (Artemia salina) lethality bioassay. Among the four fractions tested, n-hexane, carbon tetrachloride, and chloroform fractions showed moderate antibacterial and antifungal activity compared to standard antibiotic, kanamycin. The average zone of inhibition was ranged from 6 to 8 mm at a concentration of 400 µg/disc. But the aqueous fraction was found to be insensitive to microbial growth. Compared to vincristine sulfate (with LC(50) of 0.52 µg/ ml), n-hexane and chloroform fractions demonstrated a significant cytotoxic activity (having LC(50) of 1.94 µg/ml and 2.13 µg/ml, respectively). The LC(50) values of the carbon tetrachloride and aqueous fraction were 4.46 µg/ml and 5.13 µg/ ml, respectively. The study confirms the moderate antimicrobial and potent cytotoxic activities of Dillenia indica leaves extract and therefore demands the isolation of active principles and thorough bioassay. PMID:21331191

  8. Para rubber seed oil: new promising unconventional oil for cosmetics.

    PubMed

    Lourith, Nattaya; Kanlayavattanakul, Mayuree; Sucontphunt, Apirada; Ondee, Thunnicha

    2014-01-01

    Para rubber seed was macerated in petroleum ether and n-hexane, individually, for 30 min. The extraction was additionally performed by reflux and soxhlet for 6 h with the same solvent and proportion. Soxhlet extraction by petroleum ether afforded the greatest extractive yield (22.90 ± 0.92%). Although antioxidant activity by means of 1, 1-diphenyl-2-picrylhydrazyl (DPPH) assay was insignificantly differed in soxhleted (8.90 ± 1.15%) and refluxed (9.02 ± 0.71%) by n-hexane, soxhlet extraction by n-hexane was significantly (p < 0.05) potent scavenged 2,2'-azino-bis(3-ethylbenzothaiazoline)-6-sulfonic acid) or ABTS radical with trolox equivalent antioxidant capacity (TEAC) of 66.54 ± 6.88 mg/100 g oil. This extract was non cytotoxic towards normal human fibroblast cells. In addition, oleic acid and palmitic acid were determined at a greater content than in the seed of para rubber cultivated in Malaysia, although linoleic and stearic acid contents were not differed. This bright yellow extract was further evaluated on other physicochemical characters. The determined specific gravity, refractive index, iodine value, peroxide value and saponification value were in the range of commercialized vegetable oils used as cosmetic raw material. Therefore, Para rubber seed oil is highlighted as the promising ecological ingredient appraisal for cosmetics. Transforming of the seed that is by-product of the important industrial crop of Thailand into cosmetics is encouraged accordingly. PMID:24976614

  9. Phospholipase A1-catalyzed hydrolysis of soy phosphatidylcholine to prepare l-?-glycerylphosphorylcholine in organic-aqueous media.

    PubMed

    Bang, Hyo-Jeong; Kim, In-Hwan; Kim, Byung Hee

    2016-01-01

    This study aimed to optimize the preparation of L-?-glycerylphosphorylcholine (l-?-GPC) via phospholipase A1 (Lecitase Ultra)-catalyzed hydrolysis of soy phosphatidylcholine (PC). The reaction was performed in n-hexane-water biphasic media in a stirred batch reactor, and modeling and optimization were conducted using response surface methodology. Optimal conditions to completely hydrolyze PC to L-?-GPC were: temperature, 50 °C; reaction time, 30 h; water content, 69 g/100 g of PC weight; and enzyme loading, 13 g/100 g of PC weight. The optimal n-hexane-to-water ratio in the medium was 5.8:1 (v/v), and 21.3g of PC was treated as the substrate in 100 mL of the medium. L-?-GPC with purity 99.3 g/100 g was obtained from the reaction products after diethyl ether extraction and silica column chromatography. These findings suggest that the use of n-hexane-water media increases the productivity of l-?-GPC compared to the aqueous media used in enzymatic reaction systems in other published studies. PMID:26212962

  10. Comparative study of antioxidant properties and total phenolic content of the extracts of Humulus lupulus L. and quantification of bioactive components by LC-MS/MS and GC-MS.

    PubMed

    Önder, Ferah Cömert; Ay, Mehmet; Sarker, Satyajit D

    2013-11-01

    In this research, antioxidant activities of various extracts obtained from Humulus lupulus L. were compared by DPPH, ABTS, FRAP, and CUPRAC assays. The amount of total phenolic components determined by the Folin-Ciocalteu reagent was found to be highest for 25% aqueous ethanol (9079 ± 187.83 mg Ferulic acid equivalent/100 g extract) and methanol-1 (directly) (8343 ± 158.39 mg Ferulic acid equivalent/100 g extract) extracts. The n-hexane extract of H. lupulus exhibited the greatest with DPPH (14.95 ± 0.03 ?g Trolox equivalent/g sample). The highest phenolic content in the ethanolic extract could be the major contributor to its highest CUPRAC activity (3.15 ± 0.44 mmol Trolox equivalent/g sample). Methanol-2 (n-hexane, acetone, and methanol) and methanol-3 (n-hexane, dichloromethane, ethylacetate, and methanol) extracts, respectively, exhibited the most potent ABTS (7.35 ± 0.03 mM Trolox equivalent) and FRAP (1.56 ± 0.35 mmol Fe(2+)/g sample) activities. Some of the components from the crude extracts were determined by LC-MS/MS and GC-MS analyses. Comparative screening of antioxidant activities of H. lupulus extracts and quantification of some major components by LC-MS/MS, qualitatively analysis of the reported ones which were optimal under negative ion SIM mode and coinjection, are going to be valuable for food and health applications. PMID:24079371

  11. Antioxidant Activity of Different Fractions of Methanolic Extract of the Golden Chanterelle Mushroom Cantharellus cibarius (Higher Basidiomycetes) from Iran.

    PubMed

    Ebrahimzadeh, Mohammad Ali; Safdari, Yaghoub; Khalili, Masoumeh

    2015-01-01

    Natural compounds with antioxidant activity can be useful for treatment of reactive oxygen species-related diseases, comprising atherosclerosis, inflammatory injury, cardiovascular disease, cancer, diabetes, Alzheimer's disease, cataracts, autism, and aging. The current study was perform to assay the antioxidant activity different fractions of methanolic extract of golden chanterelle mushroom Cantharellus cibarius, a mushroom found in the north of Iran. Different fractions of methanolic extract of this mushroom, including n-hexane, chloroform, ethyl acetate, n-butanol, and water, were evaluated for antioxidant activity using six in vitro assay systems. Mushroom fruit was obtained from the local market, Sari (northern Iran). The n-hexane fraction had higher amounts of flavonoids contents (40.01 ± 1.30 mg quercetin equivalent g-1 of extract) and the highest exhibition of nitric oxide scavenging activity (77.21 ± 1.48%). The highest content of phenol was observed in the n-butanol fraction, which was 40.97 ± 0.99 mg gallic acid equivalent g-1 of extract. Among all the fractions, the ethyl acetate fraction was found to show higher DPPH scavenging activity (33.43 ± 1.30%) and the aqueous fraction to display the most reducing power. The highest Fe2+ chelating activity was observed in the chloroform fraction and then in the n-hexane fraction (86.13 ± 1.61 and 80.68 ± 2.07, respectively). The results all together signify C. cibarius as a valuable source of natural bioactive compounds with antioxidant activity. PMID:26349513

  12. Viscosities of nonelectrolyte liquid mixtures. I. binary mixtures containing p-dioxane

    NASA Astrophysics Data System (ADS)

    Oswal, S. L.; Phalak, R. P.

    1992-03-01

    Viscosity measurements are reported for p-dioxans with cyclohexane, n-hexane, benzene, toluene, carbon tetrachloride, tetrachloroethane, chloroform, pentachloroethane, and ethyl acetate at 303.15 K. Excess Gibbs energies of activation ?G *E of viscous flow have been calculated with Eyring's theory of absolute reaction rates. The deviations of the viscosities from a linear dependence on the mole fraction and values of ?G *E for binary mixtures have been explained in terms of molecular interactions between unlike pairs. The Prigogine-Flory-Patterson theory has been used to estimate the excess viscosity, ? ln ?, and corresponding enthalpy ln ? H, entropy ln ? S, and free volume ln ? v terms for binary mixtures of p-dioxane with cyclohexane, n-hexane, benzene, toluene, carbon tetrachloride, and chloroform. Estimates of excess viscosities from this theory for p-dioxane with benzene, toluene, and carbon tetrachloride are good, while for the other three mixtures they are poor. The local-composition thermodynamic model of Wei and Rowley estimates the excess viscosity quite well even for p-dioxane mixtures with cyclohexane and n-hexane.

  13. Simultaneous determination of eight pesticide residues in coconut using MSPD and GC/MS.

    PubMed

    Silva, Maria Geovânia Dantas; Aquino, Adriano; Dórea, Haroldo Silveira; Navickiene, Sandro

    2008-07-30

    A simple and effective extraction method based on matrix solid-phase dispersion (MSPD) was developed to determine dimethoate, malathion, lufenuron, carbofuran, 3-hydroxycarbofuran, thiabendazole, difenoconazole and trichlorfon in coconut pulp using gas chromatography-mass spectrometry with selected ion monitoring (GC/MS, SIM). Different parameters of the method were evaluated, such as type of solid-phase (C(18), alumina, silica-gel and Florisil), the amount of solid-phase and eluent (dichloromethane, acetone, ethyl acetate, acetonitrile, n-hexane and n-hexane:ethyl acetate (1:1, v/v)). The best results were obtained using 0.5 g of coconut pulp, 1.0 g of C(18) as dispersant sorbent, 1.0 g of Florisil as clean-up sorbent and acetonitrile saturated with n-hexane as eluting solvent. The method was validated using coconut pulp samples fortified with pesticides at different concentration levels (0.25-1.0 mg kg(-1)). Average recoveries (four replicates) ranged from 70.1% to 98.7%, with relative standard deviations between 2.7% and 14.7%, except for lufenuron and difenoconazole, for which recoveries were 47.2% and 48.2%, respectively. Detection and quantification limits for coconut pulp ranged from 0.02 to 0.17 mg kg(-1) and from 0.15 to 0.25 mg kg(-1), respectively. PMID:18585339

  14. Functionalized hollow siliceous spheres for VOCs removal with high efficiency and stability.

    PubMed

    Wang, Hongning; Tang, Mei; Zhang, Ke; Cai, Daofei; Huang, Weiqiu; Chen, Ruoyu; Yu, Chengzhong

    2014-03-15

    Functionalized hollow siliceous spheres (HSSs) have been prepared by surface modification with trimethylchlorosilane (TMCS) for the removal of volatile organic compounds (VOCs). The resultant HSSs-TMCS possesses a uniform and well-dispersed hollow spherical structure, high surface area, large total pore volume, high VOCs adsorption capacity, and small water vapor adsorption capacity. The adsorption and desorption performance of HSSs-TMCS under static (n-hexane and 93# gasoline) and dynamic (n-hexane) conditions was investigated. Compared with commercial silica gel (SG) and activated carbon (AC), HSSs-TMCS show higher capacity of adsorbing n-hexane and 93# gasoline with good stability and low water vapor adsorption capacity under static adsorption conditions, higher dynamic adsorption capacity and stable breakthrough time under dynamic adsorption conditions. The high efficiency and stability of functionalized HSSs are associated with their unique hollow morphology and structure parameters. The designed HSSs-TMCS with high VOCs removal capacity and recyclability are promising candidates for the treatment of air pollution. PMID:24486614

  15. Spongiform immobilization architecture of ionotropy polymer hydrogel coentrapping alcohol oxidase and horseradish peroxidase with octadecylsilica for optical biosensing alcohol in organic solvent.

    PubMed

    Wu, Xiao Jun; Choi, Martin M F

    2004-08-01

    An organic-phase optical alcohol biosensor consisting of alcohol oxidase and horseradish peroxidase coimmobilized in a spongiform hydrogel matrix of hydroxethyl carboxymethyl cellulose, an adduct of 3-methoxy-4-ethoxy benzaldehyde, 4-tert-butylpyridinium acetohydrazone, silica gel particles, and octadecylsilica particles in conjunction with an optical oxygen transducer has been successfully fabricated. The novel enzyme entrapment structure was mainly characterized with desirable solvent permeability, high efficiency of mass transfer for reactants, and good accessibility and stability of the immobilized enzymes. The biosensor could work in water-miscible solvent such as a solvent mixture of acetonitrile and phosphate aqueous buffer, as well as hydrophobic organic solvent such as n-hexane. The biosensor had the highest sensitivity to methanol in both solvent systems. Under the stop-flow mode, the biosensor had the analytical working ranges from 80 microM to 90 mM methanol in n-hexane and 0.10 to 90 mM methanol in acetonitrile/buffer. When the biosensor functioned in n-hexane, it could take benzaldehyde as an alcohol substrate and was free from any pH disturbance. In the presence of coimmobilized horseradish peroxidase, the operational life of the biosensor was 60 assays and the shelf life was longer than two weeks. The biosensor has been satisfactorily applied to the determination of methanol in commercial gasoline-methanol blend samples. PMID:15283561

  16. Laminar burning velocities at high pressure for primary reference fuels and gasoline: Experimental and numerical investigation

    SciTech Connect

    Jerzembeck, S.; Peters, N.; Pepiot-Desjardins, P.; Pitsch, H.

    2009-02-15

    Spherical flames of n-heptane, iso-octane, PRF 87 and gasoline/air mixtures are experimentally investigated to determine laminar burning velocities and Markstein lengths under engine-relevant conditions by using the constant volume bomb method. Data are obtained for an initial temperature of 373 K, equivalence ratios varying from {phi}=0.7 to {phi}=1.2, and initial pressures from 10 to 25 bar. To track the flame front in the vessel a dark field He-Ne laser Schlieren measurement technique and digital image processing were used. The propagating speed with respect to the burned gases and the stretch rate are determined from the rate of change of the flame radius. The laminar burning velocities are obtained through a linear extrapolation to zero stretch. The experimentally determined Markstein numbers are compared to theoretical predictions. A reduced chemical kinetic mechanism for n-heptane and iso-octane was derived from the Lawrence Livermore comprehensive mechanisms. This mechanism was validated for ignition delay times and flame propagation at low and high pressures. In summary an overall good agreement with the various experimental data sets used in the validation was obtained. (author)

  17. Oxides of Nitrogen Emissions from the Combustion of Monodisperse Liquid Fuel Sprays. Ph.D. Thesis

    NASA Technical Reports Server (NTRS)

    Sarv, H.

    1985-01-01

    A study of NO sub x formation in a one dimensional monodisperse spray combustion system, which allowed independent droplet size variation, was conducted. Temperature, NO and NO sub x concentrations were measured in the transition region, encompassing a 26 to 74 micron droplet size range. Emission measurements of hydrocarbons, carbon monoxide, carbon dioxide and oxygen were also made. The equivalence ratio was varied between 0.8 and 1.2 for the fuels used, including methanol, isopropanaol, n-heptane and n-octane. Pyridine and pyrrole were added to n-heptane as nitrogen-containing additives in order to simulate synthetic fuels. Results obtained from the postflame regions using the pure fuels indicate an optimum droplet size in the range of 43 to 58 microns for minimizing NO sub x production. For the fuels examined, the maximum NO sub x reductions relative to the small droplet size limit were about 10 to 20% for lean and 20 to 30% for stoichiometric and rich mixtures. This behavior is attributed to droplet interactions and the transition from diffusive to premixed type of burning. Preflame vaporization controls the gas phase stoichiometry which has a significant effect on the volume of the hot gases surrounding a fuel droplet, where NO sub x is formed.

  18. Conductivity study of microemulsions. Dependence of structural behavior of water/oil systems on surfactant, cosurfactant, oil, and temperature

    SciTech Connect

    Bisal, S.; Bhattacharya, P.K.; Moulik, S.P. )

    1990-01-11

    Structural features of w/o microemulsions have been conductometrically evaluated. The radius of the water pool, the effective radius of the droplets, their number per unit volume, the effective surface area of the water pool, and the aggregation number of the surfactant and cosurfactant molecules per droplet in the oil/water interphase have been estimated. Three oils (n-heptane, n-decane, and xylene), three surfactants (CTAB, SDS, and AOT) and two cosurfactants (1-butanol and n-hexylamine) have been used; their effects on the structural properties of microemulsions have been studied at two different temperatures, 293 and 303 K, at two weight ratios of surfactant/cosurfactant, 0.33 and 0.50. The droplet radius has been found to be oil dependent and follows the order n-heptane < n-decane < xylene. The values at 293 K are greater than those at 303 K. The dependence of the radius on the surfactant is in the order SDS > AOT > CTAB. 1-Butanol yields greater radius than n-hexylamine with SDS and AOT, and the order is reversed with CTAB. The aggregation number of the surfactant and cosurfactant per droplet increases and decreases, respectively, with elevation of temperature. The R{sub e}/R{sub W} (ratio of the effective radius of the droplet and the radius of its water core) remains fairly constant under all situations, the average value being 1.15 {plus minus} 0.10.

  19. Group type analysis of asphalt by column liquid chromatography

    SciTech Connect

    Zhang, C.; Yang, J.; Xue, Y.; Li, Y.

    2008-07-01

    An improved analysis method for characterization of asphalt was established. The method is based on column chromatography technique. The asphalts were separated into four groups: saturates, aromatics, resins, and asphaltenes, quantitatively. About 0.1 g of sample was required in each analysis. About 20 mL of n-heptanes was used to separate out saturates first. Then about 35 mL of n-heptanes/dichloromethane (.5, v/v) mixture was used to separate out aromatics. About 30 mL of dichloromethane/tetrahydrofuran (1/3, v/v) mixture was used to separate out resin. The quality of the separation was confirmed by infrared spectra (IR) and {sup 1}H NMR analysis. The model compounds, tetracosan for saturates, dibenz(o)anthracen for aromatics, and acetanilide for resins were used for verification. The IR and {sup 1}H NMR analysis of the prepared fractions from the column liquid chromatography were in good agreement that of pure reagents.

  20. Screening of crude oils for asphalt precipitation: Theory, practice, and the selection of inhibitors

    SciTech Connect

    Boer, R.B. de; Leerlooyer, K.; Bergen, A.R.D. van ); Eigner, M.R.P.

    1995-02-01

    This paper describes a simple method to screen crude oils for their tendency to precipitate asphalt, which may cause problems during production. The method is based on a thermodynamic model of asphalt solubility, derived earlier by Flory and Huggins. The most important parameters in this model are the Hildebrand solubility parameters for oil and asphaltene, and their molar volumes. The oil parameters can all be correlated with the in-situ density of the crude. It is shown that heavy crudes usually will give fewer problems with asphalt precipitation, despite their higher asphaltene content, certainly if the reservoir pressure is close to bubblepoint pressure. Consequently, the tendency for asphalt precipitation is mainly determined by three parameters: the extent to which the crude is undersaturated with gas, the density of the crude at reservoir conditions, and its saturation with asphalt at downhole conditions. Apart from the simple screening method, more elaborate methods are described to assess the potential for asphalt precipitation more accurately; asphaltene analysis on produced reservoir fluid and tank oil; n-heptane titration of the tank oil; visual inspection of a bottom-hole sample in a high-pressure cell during pressure reduction; and dynamic flow tests on tank oil after n-heptane addition.

  1. Bilayers in nanoparticle-doped polar mesogens

    NASA Astrophysics Data System (ADS)

    Lorenz, Alexander; Agra-Kooijman, Deña M.; Zimmermann, Natalie; Kitzerow, Heinz-S.; Evans, Dean R.; Kumar, Satyendra

    2013-12-01

    Structures of the mesophases of five members of the 4-n-alkyl-4'-cyanobiphenyl homologous series (4-n-butyl-4'-cyanobiphenyl to 4-n-octyl-4'-cyanobiphenyl) doped with milled BaTiO3 nanoparticles were investigated by x-ray scattering. Clear solutions of each of the 4-n-alkyl-4'-cyanobiphenyls were first prepared in n-heptane and then doped with an n-heptane/nanoparticle dispersion, which led to gelation. The nanogels were found to be one-dimensional, multilayered, smectic nanostructures in each case. Surprisingly, a characteristic layer spacing of 4.5 nm was observed in all five homologues. Synchrotron x-ray scattering study of the multilayer structures of doped 4-n-pentyl-4'-cyanobiphenyl and 4-n-octyl-4'-cyanobiphenyl revealed nine orders of the primary Bragg reflection which were used to calculate the electron density profiles of the multilayers by Fourier analysis. The multilayers were found to consist of molecular bilayers wherein the mesogens were arranged in a head-to-head assembly of the polar head groups. The alkyl tails of the mesogenic molecules were freely movable and the tail-to-tail assembly was stabilized by heptane. The dissolved nanoparticles clearly induced a new self-assembled nanostructure in which the rigid aromatic part, and not the overall length, of the molecules defined the layer spacing.

  2. Glycerol monooleate reverse micelles in nonpolar solvents: computer simulations and small-angle neutron scattering.

    PubMed

    Bradley-Shaw, Joshua L; Camp, Philip J; Dowding, Peter J; Lewtas, Ken

    2015-03-19

    The formation of glycerol monooleate reverse micelles in n-heptane and toluene at room temperature is studied using molecular-dynamics simulations and small-angle neutron scattering. The glycerol monooleate concentrations under consideration are in the range of 5-20 wt %. Under these conditions, spontaneous reverse-micelle formation is observed on the simulation timescale (up to 30 ns). From simulations, the typical dimensions (semiaxes) of the equivalent ellipsoids with the same masses and moments of inertia are in the range of 15-23 Å, with instantaneous shapes that are slightly nonspherical. By analyzing the scattering form factors from simulation and experiment, the radii of gyration of the reverse micelles are determined to be approximately 15 Å. The number of glycerol monooleate molecules in a reverse micelle is smaller in toluene (?20) than in n-heptane (?30), but the overall dimensions are similar due to greater penetration of the toluene in to the reverse micelle. The effects of low concentrations (1 wt %) of water, acetic acid, and ethanol on the reverse-micelle dimensions are determined. The overall structural effects are small, but the distributions of the molecules within the reverse micelles are shown to be sensitive to the molecular polarity. PMID:25721707

  3. Spectroscopic studies of intramolecular proton transfer in 2-(4-fluorophenylamino)-5-(2,4-dihydroxybenzeno)-1,3,4-thiadiazole.

    PubMed

    Gago?, Mariusz; Matwijczuk, Arkadiusz; Kami?ski, Daniel; Niewiadomy, Andrzej; Kowalski, Rados?aw; Karwasz, Grzegorz P

    2011-01-01

    Spectroscopic studies of the biologically active compound 2-(4-fluorophenylamino)-5-(2,4-dihydroxybenzeno)-1,3,4-thiadiazole (FABT), have been performed. Absorption studies in the UV-Vis region for FABT in polar solvents, like water or ethanol, exhibit the domination of the enol form over its keto counterpart, with a broad absorption band centered around 340 nm. In non-polar solvents such as n-heptane or heavier alkanes the 340 nm absorption band disappears and an increase of the band related to the keto form (approximately 270 nm) is observed. Fluorescence spectra (with 270 nm and 340 nm excitation energies used) show a similar dependence: for FABT in 2-propanol a peak at about 400 nm dominates over that at 330 nm while in n-heptane this relation is reversed. The solvent dependent equilibrium between the keto and enol forms is further confirmed by FTIR and Raman spectroscopies. As can be expected, this equilibrium also shows some temperature dependences. We note that the changes between the two tautomeric forms of FABT are not related to the permanent dipole moment of the solvent but rather to its dipole polarizability. PMID:20535632

  4. The effect of azeotropism on combustion characteristics of blended fuel pool fire.

    PubMed

    Ding, Yanming; Wang, Changjian; Lu, Shouxiang

    2014-04-30

    The effect of azeotropism on combustion characteristics of blended fuel pool fire was experimentally studied in an open fire test space of State Key Laboratory of Fire Science. A 30 cm × 30 cm square pool filled with n-heptane and ethanol blended fuel was employed. Flame images, burning rate and temperature distribution were collected and recorded in the whole combustion process. Results show that azeotropism obviously dominates the combustion behavior of n-heptane/ethanol blended fuel pool fire. The combustion process after ignition exhibits four typical stages: initial development, azeotropic burning, single-component burning and decay stage. Azeotropism appears when temperature of fuel surface reaches azeotropic point and blended fuel burns at azeotropic ratio. Compared with individual pure fuel, the effect of azeotropism on main fire parameters, such as flame height, burning rate, flame puffing frequency and centerline temperature were analyzed. Burning rate and centerline temperature of blended fuel are higher than that of individual pure fuel respectively at azeotropic burning stage, and flame puffing frequency follows the empirical formula between Strouhal and Froude number for pure fuel. PMID:24632362

  5. [Determination of the four generic fractions of aged bitumen by thin-layer chromatography with flame ionization detection].

    PubMed

    Feng, Zhengang; Zhang, Jianbin; Li, Xinjun; Yu, Jianying

    2015-02-01

    The aging process of bitumen has been paid more and more attention by the researchers. The four generic fractions (saturates, aromatics, resins and asphaltenes) of bitumen change significantly during the aging process. The analysis of the changes of the four generic fractions of bitumen is very helpful to reveal the bitumen aging mechanisms and guide its engineering applications. In this study, the bitumen was aged by thin film oven test (TFOT) , pressurized aging vessel (PAV) test and ultraviolet (UV) aging test, respectively. Then the four generic fractions of bitumen before and after aging were analyzed by thin-layer chromatography with flame ionization detection (TLC-FID) , which was further compared with the solubility procedures and chromatographic technique ( named as Corbett method). The compositions of the expanded solvents were also investigated. Finally, the correlation between the TLC-FID and Corbett method was further studied, which revealed a proper TLC-FID meth- od for detection of aged bitumen. The bitumen solution dissolved by dichloromethane was successively expanded by n-heptane, toluene/n-heptane (80 :20, v/v) and toluene/ethanol (55: 45, v/v) , followed by TLC-FID. This method is of great significance for the analysis of the four generic fractions of bitumen and for the exploration of bitumen aging mechanisms. PMID:25989694

  6. Alkylphenol and bisphenol A levels in rubber products.

    PubMed

    Ozaki, A; Baba, T

    2003-01-01

    Levels of p-t-butylphenol (PTBP), p-t-octylphenol (PTOP), p-nonylphenol (NP) and bisphenol A (BPA) in rubber products in food-contact use, infant-related use and other uses are reported. Of 60 rubber products tested, PTOP was found in three in a concentration range of 2.2-37 microgram g(-1), and NP in 15 in a concentration range of 2.6-513 microgram g(-1). PTBP and BPA were not found in any sample. PTOP and NP were not detected in any infant-related sample, regardless of the material type. In contrast, among the samples with food contact and with other uses, the percentages containing PTOP or NP were 33 and 43%, respectively. A migration test was performed on eight samples containing NP and used in food-contact environments. The migration level of NP from spatulas to n-heptane was 0.83-1.52 microgram ml(-1). The average migration rates to water, 20% ethanol and n-heptane were 0.03, 0.7 and 6.6%, respectively. PMID:12519724

  7. A reduced thermokinetic model for the autoignition of fuels with variable octane ratings

    SciTech Connect

    Schreiber, M.; Sakak, A.S.; Lingens, A.; Griffiths, J.F.

    1994-12-31

    The autoignition characteristics of the reference fuels i-octane, n-heptane, and their mixtures at temperatures 600--1,500 K and pressures ranging 0.3--4.2 MPa are studied by means of a reduced kinetic mechanism comprising five species in six reactions altogether. The scheme is readily adaptable to mixtures of the primary reference fuels via input of an octane number between 0 (= n-heptane) and 100 (= i-octane). Emphasis is placed on the dependence of ignition delay on gas temperature, on the evolution of reaction as portrayed in the temperature-time records, and on the multitude of dynamic features, e.g., two-stage (or multistage) ignition and negative temperature coefficient characteristics inherent to alkane combustion. The reduced model was fitted to numerical results derived from quantitative kinetic modelling and validated against currently available data from experimental systems. It was originally designed for application in a computational fluid dynamics code based on a transport equation for the joint probability density function (PDF) of the reacting species. Flame propagation and engine ``knock`` may thus be described by one consistent model.

  8. Droplet Burns in the Fiber-Supported Droplet Combustion Experiment

    NASA Technical Reports Server (NTRS)

    2003-01-01

    A fuel droplet burns in the Fiber-Supported Droplet Combustion (FSDC) Experiment on STS-94, July 4 1997, MET:02/19:20 (approximate). This experiment, performed in the Middeck Glovebox, allows us to study the burning of fuels such as n-heptane, n-decane, methanol, ethanol, methanol/water mixtures, and heptane/hexadecane mixtures in droplets as large as 6 mm (nearly 1/4 inch). In this sequence, you see the burn of a 5mm droplet of n-heptane, in a 30% O2/He environment at 1 atmosphere pressure. The droplet (looking bright pink because of reflected light) hangs suspended from the supporting fiber. FSDC-2 studied fundamental phenomena related to liquid fuel droplet combustion in air. Pure fuels and mixtures of fuels were burned as isolated single and dual droplets with and without forced air convection. The FSDC guest investigator was Forman Williams, University of California, San Diego. The experiment was part of the space research investigations conducted during the Microgravity Science Laboratory-1R mission (STS-94, July 1-17 1997). Advanced combustion experiments will be a part of investigations plarned for the International Space Station. (279KB JPEG, 1350 x 2026 pixels; downlinked video, higher quality not available) The MPG from which this composite was made is available at http://mix.msfc.nasa.gov/ABSTRACTS/MSFC-0300175.html.

  9. A path flux analysis method for the reduction of detailed chemical kinetic mechanisms

    SciTech Connect

    Sun, Wenting; Ju, Yiguang; Chen, Zheng; Gou, Xiaolong

    2010-07-15

    A direct path flux analysis (PFA) method for kinetic mechanism reduction is proposed and validated by using high temperature ignition, perfect stirred reactors, and steady and unsteady flame propagations of n-heptane and n-decane/air mixtures. The formation and consumption fluxes of each species at multiple reaction path generations are analyzed and used to identify the important reaction pathways and the associated species. The formation and consumption path fluxes used in this method retain flux conservation information and are used to define the path indexes for the first and the second generation reaction paths related to a targeted species. Based on the indexes of each reaction path for the first and second generations, different sized reduced chemical mechanisms which contain different number of species are generated. The reduced mechanisms of n-heptane and n-decane obtained by using the present method are compared to those generated by the direct relation graph (DRG) method. The reaction path analysis for n-decane is conducted to demonstrate the validity of the present method. The comparisons of the ignition delay times, flame propagation speeds, flame structures, and unsteady spherical flame propagation processes showed that with either the same or significantly less number of species, the reduced mechanisms generated by the present PFA are more accurate than that of DRG in a broad range of initial pressures and temperatures. The method is also integrated with the dynamic multi-timescale method and a further increase of computation efficiency is achieved. (author)

  10. Interaction forces between asphaltene surfaces in organic solvents.

    PubMed

    Wang, Shengqun; Liu, Jianjun; Zhang, Liyan; Masliyah, Jacob; Xu, Zhenghe

    2010-01-01

    The colloidal interactions between asphaltene surfaces in heptol, a mixture of n-heptane and toluene, were studied for the first time by colloidal force measurements using an atomic force microscope (AFM). Asphaltenes were deposited on silica wafers and silica spheres using the Langmuir-Blodgett upstroke technique. The results showed that the ratio of toluene to heptane can significantly change solvent quality in terms of the ability to solubilize asphaltenes and hence the nature and the magnitude of the interaction forces between asphaltene surfaces. In pure toluene, there is a steric long-range repulsion which can be well fitted by the scaling theory of polymer brushes. As toluene volume fraction in heptol (Phi(T)) is gradually decreased from Phi(T) = 1 (pure toluene) to Phi(T) = 0 (pure n-heptane), the steric repulsion reduced and changed to weak attraction when Phi(T) < 0.2. The attraction in heptane can be fitted by van der Waals forces alone which are thus believed to promote asphaltene aggregation, leading to asphaltene precipitation. The results obtained in this study provide an insight into interactions that determine asphaltene behavior in an organic medium and hence in crude oils. PMID:19645456

  11. Lipase from Solvent-Tolerant Pseudomonas sp. DMVR46 Strain Adsorb on Multiwalled Carbon Nanotubes: Application for Enzymatic Biotransformation in Organic Solvents.

    PubMed

    Vrutika, Patel; Datta, Madamwar

    2015-11-01

    Immobilization of biocatalysts onto particulate carriers has been widely explored for recycling of biocatalyst. However, surface properties often affect the amount of biocatalysts immobilized, their bioactivity and stability, hampering their wide applications. The aim of this work was to elucidate the importance of nanoimmobilization system in organic synthesis. The surface of multiwalled carbon nanotubes (MWCNTs) was functionalized with a mixture of concentrated acids to create an interface for enzyme immobilization. Successful functionalization and enzyme immobilization was structurally evidenced by transmision electron microscopy analysis and Fourier-transform infrared spectroscopy analysis. Furthermore, immobilized enzyme was exploited for the synthesis of flavoured ester ethyl butyrate in the presence of n-heptane. Optimized conditions for enhanced ester synthesis was found to be 8.5 pH, 40 °C, 150 rpm, 0.15:0.2 M substrate molar ratio (ethanol/butyric acid) and n-heptane as reaction medium. Utmost 81 % of ester synthesis was obtained using immobilized lipase quite higher in comparison to that of free lipase. The activation energy indicated a lower energy requirement for immobilization of lipase on the surface of functionalized MWCNTs. In summary, immobilization of lipase on functionalized MWCNTs by simple adsorption method displayed excellent properties for enzyme stability and reusability, indicating its potential for application in organic synthesis. PMID:26329889

  12. Fiber-Supported Droplet Combustion Experiment on STS-94

    NASA Technical Reports Server (NTRS)

    2003-01-01

    A fuel droplet burns in the Fiber-Supported Droplet Combustion (FSDC) Experiment on STS-94, July 4 1997, MET:02/19:20 (approximate). This experiment, performed in the Middeck Glovebox, allows us to study the burning of fuels such as n-heptane, n-decane, methanol, ethanol, methanol/water mixtures, and heptane/hexadecane mixtures in droplets as large as 6 mm (nearly 1/4 inch). In this sequence, you see the burn of a 5mm droplet of n-heptane, in a 30% O2/He environment at 1 atmosphere pressure. The droplet (looking bright pink because of reflected light) hangs suspended from the supporting fiber. FSDC-2 studied fundamental phenomena related to liquid fuel droplet combustion in air. Pure fuels and mixtures of fuels were burned as isolated single and dual droplets with and without forced air convection. The FSDC guest investigator was Forman Williams, University of California, San Diego. The experiment was part of the space research investigations conducted during the Microgravity Science Laboratory-1R mission (STS-94, July 1-17 1997). Advanced combustion experiments will be a part of investigations plarned for the International Space Station.(467KB, 18-second MPEG, screen 160 x 120 pixels; downlinked video, higher quality not available) A still JPG composite of this movie is available at http://mix.msfc.nasa.gov/ABSTRACTS/MSFC-0300174.html.

  13. Development and application of a comprehensive soot model for 3D CFD reacting flow studies in a diesel engine

    SciTech Connect

    Hong, Sangjin; Wooldridge, Margaret S.; Im, Hong G.; Assanis, Dennis N.; Pitsch, Heinz

    2005-10-01

    A three-dimensional reacting flow modeling approach is presented for diesel engine studies that can be used for predictions of trends in soot emissions for a wide range of operating conditions. The modeling framework employs skeletal chemistry for n-heptane for ignition and combustion, and links acetylene chemistry to the soot nucleation process. The soot model is based on integration and modification of existing submodels for soot nucleation, agglomeration, oxidation, and surface growth. With the optimized modeling parameters, the simulations agree well with results of high-pressure shock tube studies of rich n-heptane mixtures, reproducing the trends for soot mass over a range of temperature and pressure conditions (T=1550-2050 K, P=20, 40, and 80 MPa). Engine simulation results for soot mass are in excellent agreement with diesel engine smoke number measurements over a range of injection timings (-11{sup o} ATDC-2.4{sup o} ATDC) and two exhaust gas recirculation levels (16 and 26-27%). The model results demonstrate that correct description of the soot formation, as well as the soot transport processes, is critical for achieving reliable predictive capabilities in engine simulations.

  14. Microgravity Droplet Combustion in CO2 Enriched Environments at Elevated Pressures

    NASA Technical Reports Server (NTRS)

    Hicks, Michael C.; Nayagam, V.; Williams, F. A.

    2007-01-01

    Microgravity droplet combustion experiments were performed in elevated concentrations of CO2 at pressures of 1.0 atm, 3.0 atm, and 5.0 atm to examine the effects of a radiatively participating suppression agent in space applications. Methanol and n-heptane droplets, with an initial diameter of 2.0 mm supported on a quartz fiber, were used in these experiments. The ambient O2 concentration was held constant at 21% and the CO2 concentrations ranged from 0% to a maximum of 70%, by volume with the balance consisting of N2 . Results from the methanol tests showed slight decreases in burning rates with increased CO2 concentrations at all ambient pressures. The n-heptane tests show slight increases in burning rates with increasing CO2 concentrations at each pressure level. Instantaneous radiative heat flux was also measured using both a broadband radiometer (i.e., wavelengths from 0.6 microns to 40.0 microns) and a narrowband radiometer (i.e., centered at 5.6 microns with a filter width at half maximum of 1.5 microns). Radiative exchanges between the droplet and surrounding gases as well as the soot field produce departures from the classical quasisteady theory which would predict a decrease in burning rates with increasing CO2 concentrations in microgravity.

  15. Modifying actions of solvent extracts from fruit and vegetable residues on 2-amino-3-methylimidazo[4,5-f]quinoline (IQ) and 2-amino-3,4-dimethylimidazo[4,5-f]quinoxaline (MeIQx) induced mutagenesis in Salmonella typhimurium TA 98.

    PubMed

    Edenharder, R; Leopold, C; Kries, M

    1995-02-01

    The edible parts of 13 fruits--apples, apricots, bananas, blackberries, sweet cherries, red currants, white grapes, oranges, peaches, pears, plums, raspberries, and strawberries--and of 12 vegetables--asparagus, green beans, broccoli, brussels sprouts, red and white cabbage, carrots, cauliflower, onions, green peppers, spinach, and tomatoes--were squeezed in order to separate juices and residues. The residues were washed, lyophilized, and extracted sequentially with n-hexane, dichloromethane, acetone, and 2-propanol. Solvent extracted materials were tested in Salmonella typhymurium TA 98 for antimutagenicity against IQ and MeIQx. We found antimutagenic activities in 96% of the n-hexane extracts, 64% of the dichloromethane extracts, 44% of the acetone extracts, and 36% of the 2-propanol extracts. Since no or only minor differences were seen between the mutagens IQ and MeIQx investigations were continued with IQ only. Additional antimutagenic activities were detected in a total of 29.6% of extracts tested when an enzyme preparation with glycosidase-activities (fecalase) was included in the assay. These activities were found in originally inactive or less active dichloromethane, acetone, and 2-propanol extracts, and are therefore strongly suggestive for the liberation of antimutagenic aglycones from inactive glycosides. The existence of possibly a multitude of antimutagenic factors in fruits and vegetables was further substantiated by: (1) solvent partitioning of the n-hexane extracts of cauliflower, peaches, and spinach; (2) separation of the n-hexane and dichloromethane extracts of cauliflower, peaches, and spinach into acidid, neutral, and basic compounds; (3) chromatographic analysis of the n-hexane and dichloromethane extracts of spinach. Taken together, antimutagenic activities were present in 32 of 36 subfractions, corresponding to 88.9%. In the green vegetables beans, broccoli, and spinach the known antimutagen chlorophyll was proven to contribute considerably to antimutagenic potency. Other important contributions may be caused by various fibers: (I) antimutagenicity of fruit and vegetable solvent extracts was extensively heat stable; (II) heating surprisingly caused an increase of antimutagenic potencies or generated new antimutagenic activities in several solvent fractions, especially of broccoli, white and red cabbage. Indeed, mutagenicity induced by IQ was strongly reduced by lignin, weakly by alginic acid and pectin A, while cellulose, gum arabic, gum guar, and xylan were ineffective. With respect to the mechanisms of antimutagenicity binding of IQ by various fibers and inhibition of cytochrome P-450-dependent monooxygenases might be of major importance since no solvent fraction of any fruit or vegetable was able to reduce mutagenic activity induced by N-OH-IQ in S. typhimurium TA 98NR. PMID:7531289

  16. Two-State Intramolecular Charge Transfer (ICT) with 3,5-Dimethyl-4-(dimethylamino)benzonitrile (MMD) and Its Meta-Isomer mMMD. Ground State Amino Twist Not Essential for ICT.

    PubMed

    Druzhinin, Sergey I; Galievsky, Victor A; Demeter, Attila; Kovalenko, Sergey A; Senyushkina, Tamara; Dubbaka, Srinivas R; Knochel, Paul; Mayer, Peter; Grosse, Christian; Stalke, Dietmar; Zachariasse, Klaas A

    2015-12-10

    From X-ray structure analysis, amino twist angles of 90.0° for 2,4-dimethyl-3-(dimethylamino)benzonitrile (mMMD), 82.7° for 4-(di-tert-butylamino)benzonitrile (DTABN), and 88.7° for 6-cyanobenzoquinuclidine (CBQ) are determined, all considerably larger than the 57.4° of 3,5-dimethyl-4-(dimethylamino)benzonitrile (MMD). This large twist leads to lengthening of the amino-phenyl bond, 143.5 pm (mMMD), 144.1 pm (DTABN), 144.6 pm (CBQ), and 141.4 pm (MMD), as compared with 136.5 pm for the planar 4-(dimethylamino)benzonitrile (DMABN). As a consequence, the electronic coupling between the amino and phenyl subgroups in mMMD, DTABN, CBQ, and MMD is much weaker than in DMABN, as seen from the strongly reduced molar absorption coefficients. The fluorescence spectrum of MMD in n-hexane at 25 °C consists of two emissions, from a locally excited (LE) and an intramolecular charge transfer (ICT) state, with a fluorescence quantum yield ratio ?'(ICT)/?(LE) of 12.8. In MeCN, a single ICT emission is found. With mMMD in n-hexane, in contrast, only LE fluorescence is observed, whereas the spectrum in MeCN originates from the ICT state. These differences are also seen from the half-widths of the overall fluorescence bands, which in n-hexane are larger for MMD than for mMMD, decreasing with solvent polarity for MMD and increasing for mMMD, reflecting the disappearance of LE and the onset of ICT in the overall spectra, respectively. From solvatochromic measurements the dipole moments ?e(ICT) of MMD (16 D) and mMMD (15 D) are obtained. Femtosecond excited state absorption (ESA) spectra at 22 °C, together with the dual (LE + ICT) fluorescence, reveal that MMD in n-hexane undergoes a reversible LE ? ICT reaction, with LE as the precursor, with a forward rate constant ka = 5.6 × 10(12) s(-1) and a back-reaction kd ? 0.05 × 10(12) s(-1). With MMD in the strongly polar solvent MeCN, ICT is faster: ka = 10 × 10(12) s(-1). In the case of mMMD in n-hexane, the ESA spectra show that ICT does not take place, contrary to MeCN, in which ka = 2.5 × 10(12) s(-1). The ICT reactions with MMD and mMMD are much faster than that of the parent compound DMABN in MeCN, with ka = 0.24 × 10(12) s(-1). Because of the very short ICT reaction times of 180 fs (MMD, n-hexane), 100 fs (MMD, MeCN), and 400 fs (mMMD, MeCN), it is clear that the picosecond fluorescence decays of these systems appear to be single exponential, due to the insufficient time resolution of 3 ps. It is concluded that the faster LE ? ICT reaction of MMD as compared with DMABN (ka = 0.24 × 10(12) s(-1) in MeCN) is caused by a smaller energy gap ?E(S1,S2) between the lowest singlet excited states and not by the large amino twist angle. Similarly, the larger ?E(S1,S2) of mMMD as compared with MMD is held responsible for its smaller ICT efficiency (no reaction in n-hexane). PMID:26559045

  17. Role of NSO compounds during primary cracking of a Type II kerogen and a Type III lignite

    USGS Publications Warehouse

    Behar, F.; Lorant, F.; Lewan, M.

    2008-01-01

    The aim of this work is to follow the generation of NSO compounds during the artificial maturation of an immature Type II kerogen and a Type III lignite in order to determine the different sources of the petroleum potential during primary cracking. Experiments were carried out in closed system pyrolysis in the temperature range from 225 to 350 ??C. Two types of NSOs were recovered: one is soluble in n-pentane and the second in dichloromethane. A kinetic scheme was optimised including both kerogen and NSO cracking. It was validated by complementary experiments carried out on isolated asphaltenes generated from the Type II kerogen and on the total n-pentane and DCM extracts generated from the Type III lignite. Results show that kerogen and lignite first decompose into DCM NSOs with minor generation of hydrocarbons. Then, the main source of petroleum potential originates from secondary cracking of both DCM and n-pentane NSOs through successive decomposition reactions. These results confirm the model proposed by Tissot [Tissot, B., 1969. Premie??res donne??es sur les me??canismes et la cine??tique de la formation du pe??trole dans les bassins se??dimentaires. Simulation d'un sche??ma re??actionnel sur ordinateur. Oil and Gas Science and Technology 24, 470-501] in which the main source of hydrocarbons is not the insoluble organic matter, but the NSO fraction. As secondary cracking of the NSOs largely overlaps that of the kerogen, it was demonstrated that bulk kinetics in open system is a result of both kerogen and NSO cracking. Thus, another kinetic scheme for primary cracking in open system was built as a combination of kerogen and NSO cracking. This new kinetic scheme accounts for both the rate and amounts of hydrocarbons generated in a closed pyrolysis system. Thus, the concept of successive steps for hydrocarbon generation is valid for the two types of pyrolysis system and, for the first time, a common kinetic scheme is available for extrapolating results to natural case studies. ?? 2007 Elsevier Ltd. All rights reserved.

  18. Minutes of the tenth meeting of the centers for the analysis of thermal/mechanical energy conversion concepts

    SciTech Connect

    DiPippo, R.

    1981-03-01

    The agenda, list of participants, and minutes of the meeting are presented. Included in the appendices are figures, data, outlines, etc. from the following presentations: 500 kW Direct-Contact Heat Exchanger Pilot Plant; LBL/EPRI Heat Exchanger Field Test, Critical Temperature and Pressure Comparisons for n-Butane/n-Pentane Mixtures; Second Law Techniques in the Correlation of Cost-Optimized Binary Power Plants; Outline of Chapter on Geothermal Well Logging; Outline and Highlights from Geothermal Drilling and Completion Technology Development Program Annual Progress: October 1979-September 1980; Geothermal Well Stimulation; World Update on Installed Geothermal Power Plants; Baca No. 1 Demonstration Flask Plant: Technical and Cost Data; Heber Binary Project; 45 mw Demonstration Plant; Raft River 5 mw Geothermal Dual-Boiling-Cycle Plant; Materials Considerations in the Design of Geothermal Power Plants; Raft River Brine Treatment for Tower Make-up; and Site Photographs of Raft River Valley.

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

    SciTech Connect

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

    2015-05-14

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

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

    NASA Astrophysics Data System (ADS)

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

    2015-05-01

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

  1. Fischer Tropsch synthesis in supercritical fluids. Quarterly technical progress report, April 1, 1995--June 30, 1995

    SciTech Connect

    Akgerman, A.; Bukur, D.B.

    1996-05-01

    Our objective for this quarter was to study the effect of co-feeding a 1-olefin on the Ruhrchemie catalyst activity and selectivity, during-both conventional Fisher-Tropsch synthesis (FTS) and FTS under supercritical conditions. We used propane as the supercritical fluid and 1-dodecene (1-C{sub 12}H{sub 24}) in this test. Motivation for this study was the work of Fujimoto and co-workers who reported that suppression of methane and enhancement of high molecular weight hydrocarbons selectivities occurs with co-feeding of 1-olefins (1-heptene, 1-tetradecene, or 1-hexadecene) during FTS under supercritical conditions, but not during the conventional FTS (Co-La catalyst supported on silica in supercritical n-pentane).The diffusion coefficients of products in supercritical fluids is discussed.

  2. A time-accurate algorithm for chemical non-equilibrium viscous flows at all speeds

    NASA Technical Reports Server (NTRS)

    Shuen, J.-S.; Chen, K.-H.; Choi, Y.

    1992-01-01

    A time-accurate, coupled solution procedure is described for the chemical nonequilibrium Navier-Stokes equations over a wide range of Mach numbers. This method employs the strong conservation form of the governing equations, but uses primitive variables as unknowns. Real gas properties and equilibrium chemistry are considered. Numerical tests include steady convergent-divergent nozzle flows with air dissociation/recombination chemistry, dump combustor flows with n-pentane-air chemistry, nonreacting flow in a model double annular combustor, and nonreacting unsteady driven cavity flows. Numerical results for both the steady and unsteady flows demonstrate the efficiency and robustness of the present algorithm for Mach numbers ranging from the incompressible limit to supersonic speeds.

  3. Combustion of liquid sprays at high pressures

    NASA Technical Reports Server (NTRS)

    Shearer, A. J.; Faeth, G. M.

    1977-01-01

    The combustion of pressure atomized fuel sprays in high pressure stagnant air was studied. Measurements were made of flame and spray boundaries at pressures in the range 0.1-9 MPa for methanol and n-pentane. At the higher test pressure levels, critical phenomena are important. The experiments are compared with theoretical predictions based on a locally homogeneous two-phase flow model. The theory correctly predicted the trends of the data, but underestimates flame and spray boundaries by 30-50 percent, indicating that slip is still important for the present experiments (Sauter mean diameters of 30 microns at atmospheric pressure under cold flow conditions). Since the sprays are shorter at high pressures, slip effects are still important even though the density ratio of the phases approach one another as the droplets heat up. The model indicates the presence of a region where condensed water is present within the spray and provides a convenient means of treating supercritical phenomena.

  4. Temperature and moisture effect on spore emission in the fungal biofiltration of hydrophobic VOCs.

    PubMed

    Vergara-Fernández, Alberto; Salgado-Ísmodes, Vanida; Pino, Miguel; Hernández, Sergio; Revah, Sergio

    2012-01-01

    The effect of temperature and moisture on the elimination capacity (EC), CO(2) production and spore emission by Fusarium solani was studied in biofilters packed with vermiculite and fed with n- pentane. Three temperatures (15, 25 and 35°C) were tested and the highest average EC (64 g m(-3) h(-1)) and lower emission of spores (2.0 × 10(3) CFU m(-3) air) were obtained at 25°C. The effect of moisture content of the packing material indicates that the highest EC (65 g m(-3) h(-1)) was obtained at 50 % moisture. However, lowest emission (1.3 × 10(3) CFU m(-3) air) was obtained at 80 % moisture. Furthermore, the results show that a slight decrease in spore emission was found with increasing moisture content. In all cases, the depletion of the nitrogen source in the biofilter induced the sporulation, a decay of the EC and increased spore emission. PMID:22375544

  5. Prediction of long-term aging of cellular plastics

    SciTech Connect

    Fan, Y.; Kokko, E.

    1995-09-01

    Chlorofluorocarbon(CFC)-based cellular plastics are facing the challenge of environmental protection. The cellular plastic industry has been looking for new blowing agents as alternatives for CFCs since the Montreal Protocol was signed in 1987. The prediction of long-term thermal performance of newly developed cellular plastics thus becomes apparent. In this paper, the model ACP aging of cellular plastic is introduced. This model was originally developed for evaluating the thermal performance of carbon dioxide, CFC-11, CFC-12, CFC-22, n-Pentane, neo-Pentane and cyclo-Pentane. In comparison with short-term measurements, the ACP program now is able to predict the aging performance of cellular plastics is to combine the short-term measurements and model simulation. 21 refs., 5 figs., 4 tabs.

  6. Catalyseur d'hydrocraquage à base de sulfure de NiMo déposé sur une zéolithe HEMT modifiée

    NASA Astrophysics Data System (ADS)

    Baalala, M.; Becue, T.; Leglise, J.; Manoli, J. M.; van Gestel, J. N. M.; Lamotte, J.; Bensitel, M.; Goupil, J. M.; Cornet, D.

    1999-02-01

    Treating a NH4EMT zeolite with a solution of (NH4)2SiF6 at 80 °C affords a solid containing amorphous SiO2 intimately mixed with the zeolite. This acidic support EMT-Si was loaded with NiMo sulfide in order to prepare a bifunctional catalyst, which was tested for the hydrogenation of benzene and the hydrocracking of n-heptane. This NiMo/EMT-Si catalyst was found more active for hydrogenation than the analogous NiMo/HY. This is ascribed to a higher dispersion of the NiMo sulfide, which is almost equally shared between the internal mesopores in the modified EMT solid, and the fissures, which were created throughout the zeolite grains upon inserting the NiMo sulfide. The catalyst with the EMT-Si support was also found more active than the NiMo/HY for the hydrocracking of heptane, with a slightly higher selectivity into heptane isomers. Le traitement d'une zéolithe NH4EMT par une solution de (NH4)2SiF6 fournit un solide comportant une phase SiO2 amorphe intimement mélangée aux parties intactes de la zéolithe. Sur ce support acide EMT-Si, on a greffé un sulfure de NiMo afin de préparer un catalyseur bifonctionnel qui a été testé dans les réactions d'hydrogénation du benzène et d'hydrocraquage du n-heptane. Ce catalyseur NiMo/EMT-Si s'avère plus actif en hydrogénation que son analogue NiMo/HY, en raison d'une meilleure dispersion du sulfure de NiMo. Sur le solide EMT modifié, le sulfure se répartit à peu près également entre les mésopores internes et les fissures crées dans les grains de zéolithe lors de l'insertion du sulfure de NiMo. Au contraire sur le support Y, une partie du sulfure est externe aux grains de zéolithe et inactive en catalyse. Le catalyseur NiMo/EMT-Si est aussi trouvé plus actif que le NiMo/HY en hydrocraquage du n-heptane, et un peu plus sélectif en isomères.

  7. An experimental and numerical investigation on the influence of external gas recirculation on the HCCI autoignition process in an engine: Thermal, diluting, and chemical effects

    SciTech Connect

    Machrafi, Hatim; Cavadias, Simeon; Guibert, Philippe

    2008-11-15

    In order to contribute to the solution of controlling the autoignition in a homogeneous charge compression ignition (HCCI) engine, parameters linked to external gas recirculation (EGR) seem to be of particular interest. Experiments performed with EGR present some difficulties in interpreting results using only the diluting and thermal aspect of EGR. Lately, the chemical aspect of EGR is taken more into consideration, because this aspect causes a complex interaction with the dilution and thermal aspects of EGR. This paper studies the influence of EGR on the autoignition process and particularly the chemical aspect of EGR. The diluents present in EGR are simulated by N{sub 2} and CO{sub 2}, with dilution factors going from 0 to 46 vol%. For the chemically active species that could be present in EGR, the species CO, NO, and CH{sub 2}O are used. The initial concentration in the inlet mixture of CO and NO is varied between 0 and 170 ppm, while that of CH{sub 2}O alters between 0 and 1400 ppm. For the investigation of the effect of the chemical species on the autoignition, a fixed dilution factor of 23 vol% and a fixed EGR temperature of 70 C are maintained. The inlet temperature is held at 70 C, the equivalence ratios between 0.29 and 0.41, and the compression ratio at 10.2. The fuels used for the autoignition are n-heptane and PRF40. It appeared that CO, in the investigated domain, did not influence the ignition delays, while NO had two different effects. At concentrations up until 45 ppm, NO advanced the ignition delays for the PRF40 and at higher concentrations, the ignition delayed. The influence of NO on the autoignition of n-heptane seemed to be insignificant, probably due to the higher burn rate of n-heptane. CH{sub 2}O seemed to delay the ignition. The results suggested that especially the formation of OH radicals or their consumption by the chemical additives determines how the reactivity of the autoignition changed. (author)

  8. Problems in Catalytic Oxidation of Hydrocarbons and Detailed Simulation of Combustion Processes

    NASA Astrophysics Data System (ADS)

    Xin, Yuxuan

    This dissertation research consists of two parts, with Part I on the kinetics of catalytic oxidation of hydrocarbons and Part II on aspects on the detailed simulation of combustion processes. In Part I, the catalytic oxidation of C1--C3 hydrocarbons, namely methane, ethane, propane and ethylene, was investigated for lean hydrocarbon-air mixtures over an unsupported Pd-based catalyst, from 600 to 800 K and under atmospheric pressure. In Chapter 2, the experimental facility of wire microcalorimetry and simulation configuration were described in details. In Chapter 3 and 4, the oxidation rate of C1--C 3 hydrocarbons is demonstrated to be determined by the dissociative adsorption of hydrocarbons. A detailed surface kinetics model is proposed with deriving the rate coefficient of hydrocarbon dissociative adsorption from the wire microcalorimetry data. In Part II, four fundamental studies were conducted through detailed combustion simulations. In Chapter 5, self-accelerating hydrogen-air flames are studied via two-dimensional detailed numerical simulation (DNS). The increase in the global flame velocity is shown to be caused by the increase of flame surface area, and the fractal structure of the flame front is demonstrated by the box-counting method. In Chapter 6, skeletal reaction models for butane combustion are derived by using directed relation graph (DRG) and DRG-aided sensitivity analysis (DRGASA), and uncertainty minimization by polynomial chaos expansion (MUM-PCE) mothodes. The dependence of model uncertainty is subjected to the completeness of the model. In Chapter 7, a systematic strategy is proposed to reduce the cost of the multicomponent diffusion model by accurately accounting for the species whose diffusivity is important to the global responses of the combustion systems, and approximating those of less importance by the mixture-averaged model. The reduced model is validated in an n-heptane mechanism with 88 species. In Chapter 8, the influence of Soret diffusion on the n-heptane/air flames is investigated numerically. In the unstretched flames, Soret diffusion primarily affects the chemical kinetics embedded in the flame structure and the net effect is small; while in the stretched flames, its impact is mainly through those of n-heptane and the secondary fuel, H2, in modifying the flame temperature, with substantial effects.

  9. The Impact of Low Octane Hydrocarbon Blending Streams on Ethanol Engine Optimization

    SciTech Connect

    Szybist, James P; West, Brian H

    2013-01-01

    Ethanol is a very attractive fuel from an end-use perspective because it has a high chemical octane number and a high latent heat of vaporization. When an engine is optimized to take advantage of these fuel properties, both efficiency and power can be increased through higher compression ratio, direct fuel injection, higher levels of boost, and a reduced need for enrichment to mitigate knock or protect the engine and aftertreatment system from overheating. The ASTM D5798 specification for high level ethanol blends, commonly called E85, underwent a major revision in 2011. The minimum ethanol content was revised downward from 68 vol% to 51 vol%, which combined with the use of low octane blending streams such as natural gasoline introduces the possibility of a lower octane E85 fuel. While this fuel is suitable for current ethanol tolerant flex fuel vehicles, this study experimentally examines whether engines can still be aggressively optimized for the resultant fuel from the revised ASTM D5798 specification. The performance of six ethanol fuel blends, ranging from 51-85% ethanol, is compared to a premium-grade certification gasoline (UTG-96) in a single-cylinder direct-injection (DI) engine with a compression ratio of 12.9:1 at knock-prone engine conditions. UTG-96 (RON = 96.1), light straight run gasoline (RON = 63.6), and n-heptane (RON = 0) are used as the hydrocarbon blending streams for the ethanol-containing fuels in an effort to establish a broad range of knock resistance for high ethanol fuels. Results show that nearly all ethanol-containing fuels are more resistant to engine knock than UTG-96 (the only exception being the ethanol blend with 49% n-heptane). This knock resistance allows ethanol blends made with 33 and 49% light straight run gasoline, and 33% n-heptane to be operated at significantly more advanced combustion phasing for higher efficiency, as well as at higher engine loads. While experimental results show that the octane number of the hydrocarbon blend stock does impact engine performance, there remains a significant opportunity for engine optimization when considering even the lowest octane fuels that are in compliance with the current revision of ASTM D5798 compared to premium-grade gasoline.

  10. A Detailed Chemical Kinetic Reaction Mechanism for n-Alkane Hydrocarbons From n-Octane to n-Hexadecane

    SciTech Connect

    Westbrook, C K; Pitz, W J; Herbinet, O; Curran, H J; Silke, E J

    2008-02-08

    Detailed chemical kinetic reaction mechanisms have been developed to describe the pyrolysis and oxidation of nine n-alkanes larger than n-heptane, including n-octane (n-C{sub 8}H{sub 18}), n-nonane (n-C{sub 9}H{sub 20}), n-decane (n-C{sub 10}H{sub 22}), n-undecane (n-C{sub 11}H{sub 24}), n-dodecane (n-C{sub 12}H{sub 26}), n-tridecane (n-C{sub 13}H{sub 28}), n-tetradecane (n-C{sub 14}H{sub 30}), n-pentadecane (n-C{sub 15}H{sub 32}), and n-hexadecane (n-C{sub 16}H{sub 34}). These mechanisms include both high temperature and low temperature reaction pathways. The mechanisms are based on our previous mechanisms for the primary reference fuels n-heptane and iso-octane, using the reaction class mechanism construction first developed for n-heptane. Individual reaction class rules are as simple as possible in order to focus on the parallelism between all of the n-alkane fuels included in the mechanisms, and these mechanisms will be refined further in the future to incorporate greater levels of accuracy and predictive capability. These mechanisms are validated through extensive comparisons between computed and experimental data from a wide variety of different sources. In addition, numerical experiments are carried out to examine features of n-alkane combustion in which the detailed mechanisms can be used to compare reactivities of different n-alkane fuels. The mechanisms for all of these n-alkanes are presented as a single detailed mechanism, which can be edited to produce efficient mechanisms for any of the n-alkanes included, and the entire mechanism, with supporting thermochemical and transport data, together with an explanatory glossary explaining notations and structural details, will be available for download from our web page.

  11. Simulations of laminar flame propagation in droplet mists

    SciTech Connect

    Neophytou, A.; Mastorakos, E.

    2009-08-15

    In order to clarify the conditions conducive to propagation of premixed flames in quiescent sprays, a one-dimensional code with detailed chemistry and transport was used. n-Heptane and n-decane, distinguished by their volatility, were studied under atmospheric and low temperature, low pressure conditions. The effects of initial droplet diameter, overall equivalence ratio {phi}{sub 0} and droplet residence time before reaching the flame front were examined. Increasing the residence time had an effect only for n-heptane, with virtually no evaporation occurring before the flame front for n-decane. The trends were only marginally correlated with the local gaseous equivalence ratio {phi}{sub eff} at the location of maximum heat release rate. {phi}{sub eff} could be as low as 0.4 (beyond the lean flammability limit), but the flame speed could still be 40% of the gaseous stoichiometric flame speed S{sub L,0}. For n-heptane, {phi}{sub eff} increased towards {phi}{sub 0} with smaller droplets while high flame speeds occurred when {phi}{sub eff} was near 1. This implied that the highest flame speed was achieved with small droplets for {phi}{sub 0} {<=} 1 and with relatively large droplets for {phi}{sub 0} > 1. In the latter case, the oxidiser was completely consumed in the reaction zone and droplets finished evaporating behind the flame where the fuel was pyrolysed. The resulting small species, mainly C{sub 2}H{sub 2}, C{sub 2}H{sub 4} and H{sub 2}, diffused back to the oxidation zone and enhanced the reaction rate there. Ultimately, this could result in flame speeds higher than S{sub L,0} even with {phi}{sub 0} = 4. For n-decane, the same trends were followed but smaller droplets were needed to reach the same {phi}{sub eff} due to the slow evaporation rate. Under low pressure and low temperature, the effects of pressure and temperature on {phi}{sub eff} and the flame speed were competitive and resulted in values close to the ones at atmospheric conditions. (author)

  12. Structural and diffusion characterizations of steam-stable mesostructured zeolitic UL-ZSM-5 materials.

    PubMed

    Vinh-Thang, Hoang; Huang, Qinglin; Ungureanu, Adrian; Ei?, Mladen; Trong-On, Do; Kaliaguine, Serge

    2006-05-01

    A series of mesoporous UL-ZSM-5 materials (Si/Al = 50) with different micro- and mesoporosity as well as crystallinity was prepared following the procedure proposed in one of our recent studies (Trong-On, D.; Kaliaguine, S. Angew. Chem. Int. Ed. 2001, 40, 3248-3251. Trong-On, D.; Kaliaguine, S. U.S. Patent 6,669,924, B1, 2003). These materials have zeolitic structure in the form of nanoparticles intergrown in the walls of the amorphous wormhole-like aluminosilicate mesopores of Al-Meso-50, which was used as a precursor in the synthesis. The structure, crystallinity, and textural properties of the synthesized materials, as well as a reference ZSM-5 zeolite sample, were determined by X-ray diffraction (XRD), transmission electron microscopy (TEM)/scanning electron microscoy (SEM) analyses, Fourier transform infrared spectroscopy (FTIR), 27Al magic angle spinning (MAS) nuclear magnetic resonance (NMR), and nitrogen adsorption/desorption techniques. The acid properties were examined by FTIR of adsorbed pyridine. UL-ZSM-5 materials were shown to be highly hydrothermally stable. The diffusion of two C7 hydrocarbons, i.e., n-heptane and toluene, in four UL-ZSM-5 materials with different microporosities, related acidities, and crystallinities were investigated using the zero-length column (ZLC) method. Furthermore, the wormhole-like mesostructured aluminosilicate precursor (Al-Meso-50) and a reference MFI zeolite sample were also investigated using the same technique. A theoretical model considering a combination of mesopore diffusion (with surface slip in the main channels) with an activated, mainly surface diffusion mechanism in the intrawall biporous structure, was proposed and employed to interpret the experimental ZLC results. A classical Knudsen type of diffusion was replaced by an activated surface slip type of diffusion mechanism in the mesopores. The transport of n-heptane in UL-ZSM-5 materials was found to be mainly controlled by mesopore diffusion in the main-channel structure, while that of toluene was dominated by the intrawall diffusion process. Diffusion activation energies of n-heptane are about 2 times higher in comparison to toluene, which has a larger kinetic diameter. The main mesopore channel structure seems to appreciably contribute to the overall mass transport. Furthermore, the effect of hydrothermal treatment (20% steam at 800 degrees C for 24 h) on the diffusion of these two sorbates on UL-ZSM-5 materials was also evaluated. PMID:16649795

  13. Localization of ferruginol, a diterpene phenol, in Cryptomeria japonica heartwood by time-of-flight secondary ion mass spectrometry.

    PubMed

    Imai, Takanori; Tanabe, Kinuko; Kato, Toshiyuki; Fukushima, Kazuhiko

    2005-06-01

    Time-of-flight secondary ion mass spectrometry (TOF-SIMS) was applied to the investigation of heartwood extractives in Sugi (Cryptomeria japonica). Sugi heartwood tissue generated secondary ions that were not produced from sapwood tissue by TOF-SIMS. Among the peculiar ions generated from heartwood, two positive ions of m/z 285 and 301 were remarkable due to their appearance in a larger mass range and with a high intensity. These two ions were not generated from heartwood tissue preextracted with n-hexane, and the n-hexane extract of Sugi heartwood produced both ions. Gas chromatography-mass spectrometry of the n-hexane extract demonstrated that ferruginol, a diterpene phenol, the molecular weight of which is 286, constituted one of the predominant constituents of the extract. Authentic ferruginol also generated both ions by TOF-SIMS. The molecular formula of the m/z 285 ion generated from Sugi heartwood tissue was estimated to be C(20)H(29)O, which corresponds well with that of ferruginol, i.e. C(20)H(30)O, by peak identification. All these results strongly suggest that the m/z 285 ion generated from Sugi heartwood tissue originated significantly from ferruginol in Sugi heartwood. By TOF-SIMS imaging, the m/z 285 ion was detected uniformly in the tracheid cell walls, in the cell walls of the axial parenchyma cells and ray parenchyma cells, and also inside these parenchyma cells. These results indicate that ferruginol was distributed almost evenly in Sugi heartwood tissue. PMID:15856284

  14. Antibacterial, anti-fungal and phytotoxic activities of Ferula narthex Boiss.

    PubMed

    Bashir, Shumaila; Alam, Mahboob; Ahmad, Bashir; Aman, Akhtar

    2014-11-01

    Crude methanolic extract of roots, aerial parts and its subsequent fractions of Ferula narthex Boiss were tested for antibacterial, anti-fungal and phytotoxic activities. Crude methanolic extract of roots and its fractions showed significant antibacterial effect against P.aeruginosa (86.95%, 73.91, 69.59, 78.26 & 73.91%) represented by percent inhibition except ethyl acetate (EtoAc) fraction. The EtoAc fraction of roots and aerial parts showed significant activity against E. coli (80%), S. typhi (81.2 & 81.25%) and S. pneumoniae (80%). The n-hexane, chloroform and aqueous fractions of aerial parts showed significant activity against P. aeruginosa (78.26, 69.56 & 73.91%). Following fungal strains (T. longifusus, C. albicans, A. flavus, M. canis, F. solani, C. glabrata) were also used for anti-fungal activity. Among tested samples only crude methanol extract of roots, n-hexane and chloroform fraction showed moderate anti-fungal activity against M. canis (40, 35 & 30%) represented by percent inhibition. The remaining fractions showed no effect on tested fungi. Different oils fractions were also tested against above fungal strains. Fraction I, II & V showed mild to moderate activity against M. canis (40, 40 & 25%). Phytotoxic effect of tested samples of roots, aerial part and its fractions showed concentration dependent growth inhibition. Maximum phytotoxic effect was noted for n-hexane and aqueous fraction (50% growth inhibition). The remaining tested samples showed mild effect on growth of Lemna minor plant. PMID:25362591

  15. Sensitive assay for measurement of volatile borneol, isoborneol, and the metabolite camphor in rat pharmacokinetic study of Borneolum (Bingpian) and Borneolum syntheticum (synthetic Bingpian)

    PubMed Central

    Cheng, Chen; Liu, Xin-wei; Du, Fei-fei; Li, Mei-juan; Xu, Fang; Wang, Feng-qing; Liu, Yang; Li, Chuan; Sun, Yan

    2013-01-01

    Aim: Both Borneolum (Chinese name Bingpian; dextrorotatory borneol) and Borneolum syntheticum (synthetic Bingpian; a mixture of optically inactive borneol and isoborneol) have been used for medicinal purposes in Chinese traditional medicine. The aim of this study was to develop a sensitive assay for measuring volatile ingredients borneol, isoborneol, and their metabolite camphor in pharmacokinetic study of Bingpian. Methods: Rat plasma samples were prepared using liquid-liquid microextraction: 70 ?L of plasma sample (containing 125 nmol/L naphthalene as the internal standard) was extracted with 35 ?L of n-hexane. The resulting n-hexane extract (20 ?L) was introduced into a gas chromatography/mass spectrometry system using programmable temperature vaporizing-based large-volume injection. The assay was validated to demonstrate its reliability for the intended use. Using this assay, pharmacokinetic studies of Bingpian, synthetic Bingpian, and Fufang-Danshen tablets (containing synthetic Bingpian) were conducted in rats. Results: The extraction efficiency for the analytes and the internal standard from plasma was almost constant with decrease in n-hexane-to-plasma volume ratio, thus enabling a small volume of extracting solvent to be used for sample preparation, and enhancing the assay sensitivity. The lower quantification limit for measuring borneol, isoborneol, and camphor in plasma was 0.98 nmol/L, which was 33–330 times more sensitive than those reported earlier for Bingpian and synthetic Bingpian. The applicability of the miniaturized liquid-liquid extraction technique could be extended to measure other volatile and nonvolatile medicinal compounds in biomatrices, which can be predicted according to the analytes' octanol/water distribution coefficient (logD) and acid dissociation constant (pKa). Conclusion: This assay is sensitive, accurate and free of matrix effects, and can be applied to pharmacokinetic studies of Bingpian, synthetic Bingpian, and Bingpian-containing herbal products. PMID:23974515

  16. Antioxidant Capacities, Phenolic Profile and Cytotoxic Effects of Saxicolous Lichens from Trans-Himalayan Cold Desert of Ladakh

    PubMed Central

    Kumar, Jatinder; Dhar, Priyanka; Tayade, Amol B.; Gupta, Damodar; Chaurasia, Om P.; Upreti, Dalip K.; Arora, Rajesh; Srivastava, Ravi B.

    2014-01-01

    Fourteen saxicolous lichens from trans-Himalayan Ladakh region were identified by morpho-anatomical and chemical characteristics. The n-hexane, methanol and water extracts of the lichens were evaluated for their antioxidant capacities. The lichen extracts showing high antioxidant capacities and rich phenolic content were further investigated to determine their cytotoxic activity on human HepG2 and RKO carcinoma cell lines. The ferric reducing antioxidant power (FRAP), 2,2?-azinobis-(3-ethylbenzothiazoline-6-sulfonic acid) diammonium salt (ABTS), 1,1-diphenyl-2-picrylhydrazyl (DPPH) and nitric oxide (NO) radical scavenging capacities and ?-carotene-linoleic acid bleaching property exhibited analogous results where the lichen extracts showed high antioxidant action. The lichen extracts were also found to possess good amount of total proanthocyanidin, flavonoid and polyphenol. The methanolic extract of Lobothallia alphoplaca exhibited highest FRAP value. Methanolic extract of Xanthoparmelia stenophylla showed the highest ABTS radical scavenging capacity. The n-hexane extract of Rhizoplaca chrysoleuca exhibited highest DPPH radical scavenging capacity. Highest antioxidant capacity in terms of ?-carotene linoleic acid bleaching property was observed in the water extract of Xanthoria elegans. Similarly, Melanelia disjuncta water extract showed highest NO scavenging capacity. Among n-hexane, methanol and water extracts of all lichens, the methanolic extract of Xanthoparmelia mexicana showed highest total proanthocyanidin, flavonoid and polyphenol content. From cytotoxic assay, it was observed that the methanolic extracts of L. alphoplaca and M. disjuncta were exhibiting high cytotoxic effects against cancer cell growth. Similarly, the water extract of Dermatocarpon vellereum, Umbilicaria vellea, X. elegans and M. disjuncta and the methanolic extract of M. disjuncta and X. stenophylla were found to possess high antioxidant capacities and were non-toxic and may be used as natural antioxidants for stress related problems. Our studies go on to prove that the unique trans-Himalayan lichens are a hitherto untapped bioresource with immense potential for discovery of new chemical entities, and this biodiversity needs to be tapped sustainably. PMID:24937759

  17. Cytotoxicity of some edible mushrooms extracts over liver hepatocellular carcinoma cells in conjunction with their antioxidant and antibacterial properties

    PubMed Central

    Sadi, Gökhan; Emsen, Bu?rahan; Kaya, Abdullah; Kocaba?, Aytaç; Ç?nar, Seval; Kartal, Deniz ?rtem

    2015-01-01

    Background: Mushrooms have been valued for their nutritive content and as traditional medicines; several important medicinal properties of mushrooms have been recognized worldwide. Objective: The purpose of this study was to elucidate the cell growth inhibitory potential of four edible mushrooms; Coprinus comatus (O.F. Mull.) Pers. (Agaricaceae), Tricholoma fracticum (Britzelm.) Kreisel (Tricholomataceae), Rhizopogon luteolus Fr. and Nordholm (Rhizopogonaceae), Lentinus tigrinus (Bull.) Fr. (Polyporaceae) on hepatocellular carcinoma (HepG2) cells in conjunction with their antioxidant and antibacterial capacities. Materials and Methods: Five different extracts of edible mushrooms were obtained using water, methanol, acetone, n-hexane and chloroform as solvent systems for cytotoxic, antioxidant and antibacterial properties. Results: C. comatus showed substantial in vitro cytotoxic activity against HepG2 cell lines with all extracts especially with chloroform 50% inhibition (IC50 value of 0.086 mg/ml) and acetone (IC50 value of 0.420 mg/ml). Chloroform extract of C. comatus had maximum amount of ?-carotene (25.94 ?g/mg), total phenolic content (76.32 ?g/mg) and lycopene (12.00 ?g/mg), and n-hexane extract of L. tigrinus had maximum amount of flavonoid (3.67 ?g/mg). While chloroform extract of C. comatus showed the highest 2, 2-diphenyl-1-picrylhydrazyl (DPPH) capturing activity (1.579 mg/ml), the best result for metal chelating activity was obtained from methanolic extract (0.842 mg/ml). Moreover, all tested mushrooms demonstrated antibacterial activity and n-hexane extract of L. tigrinus and acetone extracts of T. fracticum were the most active against tested microorganism. Conclusion: These results indicate that different extracts of investigated mushroom have considerable cytotoxic, antioxidant and antibacterial properties and may be utilized as a promising source of therapeutics. PMID:26109775

  18. Hepatoprotective effects of flavonoids from shekwasha (Citrus depressa) against D-galactosamine-induced liver injury in rats.

    PubMed

    Akachi, Toshiyuki; Shiina, Yasuyuki; Ohishi, Yayoi; Kawaguchi, Takumi; Kawagishi, Hirokazu; Morita, Tatsuya; Mori, Makoto; Sugiyama, Kimio

    2010-01-01

    We attempted to isolate the constituent(s) responsible for the suppressive effect of the juice of shekwasha, a citrus produced in Okinawa Prefecture, on D-galactosamine (GalN)-induced liver injury in rats. Liver injury-suppressive activity, as assessed by plasma alanine aminotransferase and aspartate aminotransferase activities, was found only in the fraction that was extracted with n-hexane when three fractions were added to the diet and fed to rats. Of five compounds isolated from the n-hexane-soluble fraction by silica gel column chromatography, three compounds had liver injury-suppressive effects when five compounds were singly force-fed to rats at a level of 300 mg/kg body wt 4 h before the injection with GalN. The structures of the three active compounds were determined as 3',4',5,6,7,8-hexamethoxyflavanone (citromitin), 4',5,6,7,8-pentamethoxyflavone (tangeretin) and 3',4',5,6,7,8-hexamethoxyflavone (nobiletin), which are known flavonoids mainly existing in citrus. Nobiletin, the most important compound in the n-hexane-soluble fraction, also had suppressive effects on liver injuries induced by carbon tetrachloride, acetaminophen and GalN/lipopolysaccharide (LPS) in addition to liver injury induced GalN. Nobiletin suppressed GalN/LPS-induced increases in plasma tumor necrosis factor (TNF)-alpha and nitric oxide (NO) concentrations and hepatic mRNA levels for inducible NO synthase and DNA fragmentation. These results suggest that nobiletin suppressed GalN/LPS-induced liver injury at least by suppressing the production of both TNF-alpha and NO. The results obtained here indicate that the hepatoprotective effect of shekwasha juice is mainly ascribed to several polymethoxy flavonoids included in the juice. PMID:20354348

  19. Balanophora spicata and Lupeol Acetate Possess Antinociceptive and Anti-Inflammatory Activities In Vivo and In Vitro

    PubMed Central

    Chen, Yuh-Fung; Ching, Chien; Wu, Tian-Shung; Wu, Chi-Rei; Hsieh, Wen-Tsong; Tsai, Huei-Yann

    2012-01-01

    Aims of the present study were to investigate effects of Balanophora spicata (BS) on antinociception and anti-inflammation both in vivo and in vitro. Crude extract of BS inhibited vascular permeability induced by histamine, serotonin, bradykinin, and PGE2, but not by PAF. Furthermore, BS crude extract, different layers (n-hexane, ethyl acetate, n-butanol, and water layer), and lupeol acetate had significant antinociceptive and anti-inflammatory effects on acetic acid-induced abdominal writhing response, formalin-induced licking behavior, carrageenan-, and serotonin-induced paw edema. The n-hexane layer had the most effective potency among all layers (IC50: 67.33?mg/kg on writhing response; IC50s: 34.2?mg/kg and 21.29?mg/kg on the early phase and late phase of formalin test, resp.). Additionally, lupeol acetate which was isolated from the n-hexane layer of BS effectively inhibited the acetic acid-induced writhing response (IC50: 28.32?mg/kg), formalin-induced licking behavior (IC50: 20.95?mg/kg), NO production (IC50: 4.102??M), iNOS expression (IC50: 5.35??M), and COX2 expression (IC50: 5.13??M) in LPS-stimulated RAW 264.7 cells. In conclusion, BS has antinociceptive and anti-inflammatory effects which may be partially due to the inhibition of changes in vascular permeability induced by histamine, serotonin, bradykinin, and PGE2 and the attenuation of iNOS and COX-2 expression. PMID:23243439

  20. Extraction and separation of thorium(IV) from lanthanides(III) with room-temperature ionic liquids containing primary amine N{sub 1923}

    SciTech Connect

    Zuo, Y.; Chen, J.; Bai, Y.; Li, D.Q.

    2008-07-01

    The extraction behavior of Th(IV) by primary amine N{sub 1923} in imidazolium-based ionic liquid namely 1-octyl-3-methylimidazolium hexafluorophosphate (N{sub 1923}/IL) was studied in this paper. Results showed that N{sub 1923}/IL had poorer extraction ability for Th(IV) than N{sub 1923} in n-heptane (N{sub 1923}/HEP). The separation coefficients between Th(IV) and lanthanides(III) ({beta}{sub Th/Ln}) were obtained and compared with those in the N{sub 1923}/HEP system. On this basis, we made a preliminary assessment for the possibility of using ionic liquids as solvents for the separation of Th(IV) from lanthanides(III) sulfate in a clean process. (authors)

  1. Extraction of rare earth metals with 2-ethylhexyl phosphonic acid mono-2-ethylhexyl ester in the presence of diethylenetriaminepentaacetic acid in aqueous phase

    SciTech Connect

    Kubota, Fukiko; Goto, Masahiro; Nakashio, Fumiyuki

    1993-07-01

    The extraction equilibria of rare earth metals with 2-ethylhexyl phosphonic acid mono-2-ethylhexyl ester (commercial name, PC-88A, henceforth abbreviated as HR) dissolved in n-heptane were measured at 303 K. It was found that rare earth metals are extracted with the dimer of the extractant, (HR){sub 2}, as follows. M{sub aq}{sup 3+} + 3(HR){sub 2 org} MR{sub 3} {center_dot} 3HR{sub org} + 3H{sub aq}{sup +} The extraction equilibrium constants of metals were obtained and compared with the extraction equilibrium constants obtained by di(2-ethylhexyl)phosphoric acid (henceforth DZEHPA). Furthermore, the extraction equilibria of rare earth metals with PC-88A in the presence of diethylenetriaminepentaacetic acid (henceforth DTPA) in an aqueous phase were also measured to discuss the effect of DTPA on the extraction of rare earth metals. 13 refs., 8 figs., 2 tabs.

  2. High-pressure combustion of binary fuel sprays

    NASA Technical Reports Server (NTRS)

    Mikami, Masato; Kono, Michikata; Sato, Jun'ichi; Dietrich, Daniel L.; Williams, Forman A.

    1995-01-01

    The ultimate objective of this study is to obtain fundamental information relevant to combustion processes that occur in fuel sprays of practical interest at high pressures in internal combustion engines. Since practical fuels are multicomponent and derived from petroleum, the present work involves the model alkane mixture of n-heptane and n-hexadecane. Since burning droplets in sprays can interact with each other, the present work involves investigation of the effects of this interaction on flame shapes and droplet burning times. The small droplets in practical combustion chambers are not significantly influenced by buoyancy. Since such small droplets are difficult to study experimentally, the present work takes advantage of microgravity to lessen buoyancy and enable information about droplet interactions to be obtained by studying larger droplets. The results are intended to provide fundamental understanding that can be used in improving descriptions of practical spray combustion.

  3. Pressure Effects in Droplet Combustion of Miscible Binary Fuels

    NASA Technical Reports Server (NTRS)

    Mikami, Masato; Habara, Osamu; Kono, Michikata; Sato, Jun-Ichi; Dietrich, Daniel L.; Williams, Forman A.

    1997-01-01

    The objective of this research is to improve understanding of the combustion of binary fuel mixtures in the vicinity of the critical point. Fiber-supported droplets of mixtures of n-heptane and n-hexadecane, initially 1 mm in diameter, were burned in room-temperature air at pressures from 1 MPa to 6 MPa under free-fall microgravity conditions. For most mixtures the total burning time was observed to achieve a minimum value at pressures well above the critical pressure of either of the pure fuels. This behavior is explained in terms of critical mixing conditions of a ternary system consisting of the two fuels and nitrogen. The importance of inert-gas dissolution in the liquid fuel near the critical point is thereby re-emphasized, and nonmonotonic dependence of dissolution on initial fuel composition is demonstrated. The results provide information that can be used to estimate high-pressure burning rates of fuel mixtures.

  4. Kinetic Analysis of Batch Ethanol Acetylation in Isothermal Non-Stationary Multiphase Systems by Lyophilized Mycelium of Aspergillus Oryzae

    PubMed Central

    Palazzi, Emilio; Molinari, Francesco; Fabiano, Bruno; Pessoa, Adalberto; Converti, Attilio

    2011-01-01

    A relatively complex network of reactions has been investigated, using as a network model the isothermal batch esterification of acetic acid with ethanol in n-heptane catalyzed by lyophilized mycelium of Aspergillus oryzae. The kinetic analysis was firstly carried out on the whole system, without any simplification, by means of the well-known integral method. Owing to the poor results obtained by this way, we developed an alternative approach, combining initial rates and integral analysis and reducing the number of empirical parameters to be determined by the use of equilibrium data. All the values of the parameters calculated according to this “composite” approach to kinetic analysis well correlate with experimental data. PMID:24031645

  5. Solution-phase photochemistry of a [FeFe]hydrogenase model compound: Evidence of photoinduced isomerisation

    SciTech Connect

    Kania, Rafal; Hunt, Neil T.; Frederix, Pim W. J. M.; Wright, Joseph A.; Pickett, Christopher J.; Ulijn, Rein V.

    2012-01-28

    The solution-phase photochemistry of the [FeFe] hydrogenase subsite model ({mu}-S(CH{sub 2}){sub 3}S)Fe{sub 2}(CO){sub 4}(PMe{sub 3}){sub 2} has been studied using ultrafast time-resolved infrared spectroscopy supported by density functional theory calculations. In three different solvents, n-heptane, methanol, and acetonitrile, relaxation of the tricarbonyl intermediate formed by UV photolysis of a carbonyl ligand leads to geminate recombination with a bias towards a thermodynamically less stable isomeric form, suggesting that facile interconversion of the ligand groups at the Fe center is possible in the unsaturated species. In a polar or hydrogen bonding solvent, this process competes with solvent substitution leading to the formation of stable solvent adduct species. The data provide further insight into the effect of incorporating non-carbonyl ligands on the dynamics and photochemistry of hydrogenase-derived biomimetic compounds.

  6. Hydrocarbons identified in extracts from estuarine water accommodated no. 2 fuel oil by gas chromatography-mass spectrometry

    NASA Technical Reports Server (NTRS)

    Lewis, B. W.; Walker, A. L.; Bieri, R. H.

    1974-01-01

    Results are presented on a computerized gas chromatograph-mass spectrometer analysis of methylene chloride and n-heptane extracts of a No. 2 fuel oil accommodated estuarine water sample. The analytical method is briefly described, and the limitations on the identifications are categorized. Some attempt was made to determine major and trace constituents in the water accommodate. Altogether 66 hydrocarbon compounds were identified specifically, and 75 compounds were partially identified. Seven compounds could be recognized as major constituents of the water accommodated oil and ten were present only as traces. The aromatic compounds found were alkyl benzenes, naphthalene, tetralin, indane, biphenyl, fluorene, anthracene, and some of their alkyl substituted isomers in the range of carbon numbers C7 to C15. Four n-alkanes, C10 to C13, were found along with four other assorted hydrocarbons.

  7. Ignition Quality Tester (IQT): An Alternative for Characterizing the Combustion Kinetics of Low Volatility Fuels

    SciTech Connect

    Osecky, E.; Bogin, G.; Ratcliff, M.; Luecke, J.; Chen, J. Y.; Zigler, B. T.

    2013-01-01

    The Ignition Quality Tester (IQT) is a constant volume spray combustion system that can be heated and pressurized to conditions that are similar to a diesel engine at top dead center. With no moving parts and the ability to handle low volatility fuels, the IQT can be a bridge between engines and traditional methods for studying chemical kinetics. By comparing experimental data with model predictions, the IQT has been used to validate skeletal kinetic models of ignition. CFD modeling of the IQT using KIVA-3V was used to predict ignition of n-heptane accurately. Operating the IQT in a regime where chemical kinetics dominates (long ignition delays) allowed NTC behavior to be observed for some isomers of heptane. Experimental results with the low volatility fuel heptamethylnonane also show NTC behavior. At long ignition delays, experimental results can be compared with 0-D detailed chemical mechanisms.

  8. Gas-liquid chromatographic headspace technique for determination of vinyl chloride in corn oil and three food-simulating solvents.

    PubMed

    Diachenko, G W; Breder, C V; Brown, M E; Dennison, J L

    1977-05-01

    A gas-liquid chromatographic headspace technique for the determination of vinyl chloride (VC) in corn oil, 50% ethanol, 3% acetic acid, and n-heptane is described. These food-simulating solvents and the corn oil are placed in septum-sealed bottles and heated to 90 degrees C, and aliquots of headspace vapor are injected into a gas-liquid chromatograph equipped with a flame ionization detector. VC may be quantitated at concentrations of 1 ppb or less. This technique was used to measure the migration of VC into corn oil and 50% ethanol from 2 unplasticized polyvinyl chloride sheets containing 0.28 and 0.44 ppm residual monomer. PMID:858701

  9. Partial Wetting in Capillary Liquid Absorption by Limestones.

    PubMed

    Taylor; Hall; Hoff; Wilson

    2000-04-15

    We report measurements of the capillary absorption (imbibition) of water, n-heptane, n-decane, n-dodecane, methanol, ethanol, propan-2-ol, and ethanol-water mixtures into a number of dry calcitic limestones. The data are analyzed on the basis of unsaturated flow theory to give values of sorptivity S for water and for each organic liquid at different temperatures. The results show that for the organic liquids S varies as (surface tension/viscosity)(1/2) but that for the water S is anomalously low, indicating partial wetting. The wettability of these limestones is discussed in relation to natural contamination of the pore surface. Copyright 2000 Academic Press. PMID:10727347

  10. [Migration of di(2-ethylhexyl) phthalate from polyvinyl chloride tubes used in preparation of foods].

    PubMed

    Tsumura, Yukari; Ishimitsu, Susumu; Hirayama, Kuni; Fujimaki, Teruhisa; Nakazawa, Hiroyuki; Tonogai, Yasuhide

    2002-08-01

    Three samples of polyvinyl chloride products for food use were examined for di(2-ethylhexyl) phthalate (DEHP) migration levels under the conditions described in the Japanese Food Sanitation Law. These samples were two kinds of tubes and one stretched film, containing 12 to 41% DEHP by weight. DEHP migration levels from them were very low, all below 0.1 ppm, into 3 kinds of food simulant; water, 4% acetic acid and 20% ethanol. However, high levels of DEHP migrated into n-heptane, 12 ppm from the stretched film sample and more than 800 ppm from the tube samples. Migration from the 2 tubes was higher than 150 ppm, the limit of residues after evaporation in containers and wraps. Though the limit of residues after evaporation is not set for equipment used in the preparation of foods, the tested tubes were considered to be unsuitable for uses in which they come into direct contact with oils, fats or oily foods. PMID:12436721

  11. On the role of organic adlayers in the anomalous water sorptivity of Lépine limestone.

    PubMed

    Ioannou, Ioannis; Hoff, William D; Hall, Christopher

    2004-11-01

    Sorptivity data are reported for the capillary absorption of water, ethanol, propan-2-ol, and n-heptane by the calcitic limestone Lépine (Lavoux à grain). The data confirm that the water sorptivity is anomalously low, an indication of partial wetting by water. Results are expressed in terms of a wetting index. The water sorptivity increases after heat treatment and chemical oxidation by hydrogen peroxide bleaching, while the sorptivity with organic liquids is unchanged. These treatments, therefore, increase the water wetting index. The results provide strong evidence that the presence of a natural organic adlayer is responsible for the anomalously low water sorptivity of this particular limestone. This natural water repellency effect may be exploited in developing chemical treatments to modify the water transport properties of stone. PMID:15380433

  12. Effect of surface conditioning on the abrasion rate of dental composites.

    PubMed

    Mair, L H

    1991-04-01

    Seven dental composites were conditioned prior to wear testing in a three body abrasion machine. The physical conditioning comprised thermal cycling or storage in water for equivalent times. Chemical conditioning was with 75 per cent ethanol or n-heptane. The results indicated that specimens conditioned by 50,000 thermal cycles had an increased surface abrasion rate. With chemical conditioning, 75 per cent ethanol increased the abrasion rate in a number of materials. Both of the latter treatments are clinically unrealistic. As the specimens in other groups were not statistically separable, the results do not support the concept that surface degradation in the mouth is a major variable for three body abrasion. PMID:2050886

  13. Enantiospecific determination of nimodipine in human plasma by liquid chromatography-tandem mass spectrometry.

    PubMed

    Mück, W M

    1995-09-29

    A direct enantiospecific HPLC assay using tandem mass spectrometric (MS-MS) detection via pneumatically-assisted electrospray has been developed for the determination of the calcium antagonist nimodipine in human plasma. By the addition of ammonium acetate (2 mM) to the purely organic eluent ethanol-n-heptane (20:80, v/v) charged species (M+NH4+) were producible by electrospray ionization at sufficient sensitivity. Routine determination of nimodipine enantiomers in human plasma in the working range of 0.5-75 microgram/l plasma for each isomer with an accuracy < or = +/- 10% and a precision of about 10% (20% close to the limit of quantification) was possible. This was comparable to the available LC-GC-MS assay, however, the time required for routine analysis of ca. 150 unknowns could be reduced from 4 weeks to 1 week. PMID:8556154

  14. Extraction of light filth from coconut: collaborative study.

    PubMed

    Thrasher, J J

    1978-07-01

    The official method for filth in coconut, 44.029, frequently produces filter papers with excessive plant debris and low hair recoveries. To overcome these deficiencies, 3 changes in the method were made: (1) the defatting step was modified to use sodium lauryl sulfate in combination with borax for better defatting; (2) 40% isopropanol was substituted for 60% ethanol as the aqueous phase for cleaner papers; and (3) mineral oil was substituted for n-heptane to improve hair recoveries. These changes resulted in higher, more reproducible recoveries of rodent hairs and insect fragments and cleaner filter papers. The method has been adopted as official first action to replace 44.029. PMID:567215

  15. [Contribution to the migration and toxicology of 2-(2'-hydroxy-3'-tert-butyl-5'-methylpheny)-5-chlorobenzotriazole].

    PubMed

    Uhde, W J; Horácek, J

    1977-01-01

    Studies on the use of an ultraviolet-absorbing agent based on hydroxybenzotriazole for commodities of low-pressure and high-pressure polyethylene and polypropylene show that the migration is only slight in aqueous and acidic foods and in foodstuffs with low alcohol content. Sunflower oil, n-heptane (as a fat-stimulating test solution) and 50% ethanol as test solutions yielded higher migration values. Gas chromatographic, polarographic and thin-layer chromatographic methods were used to determine the ultraviolet-absorbing agent. Concerns about a possible photosensitizing effect of 2-(2'-hydroxy-3'-tert-butyl-5'-methylphenyl)-5-chlorobenzotriazole were experimentally tested and turned out to be unfounded. From the viewpoint of safety, there are no contraindications to the use of polyolefines in packing materials for most foods. As to fat-containing and strongly alcoholic foodstuffs, the authorization should be conditioned on the circumstances of use. PMID:927485

  16. Chiral separation of beta-adrenergic blockers on CelluCoat column by HPLC.

    PubMed

    Ali, Imran; Gaitonde, Vinay D; Aboul-Enein, Hassan Y; Hussain, Afzal

    2009-04-30

    The chiral separation of 10 beta-adrenergic blockers (acebutalol, alprenolol, bufuralol, bisoprolol, celiprolol, carazolol, indenolol, metoprolol, oxprenolol and propranolol) was achieved on CelluCoat column (250 mm x 4.6mm, 5 microm particle size). The mobile phases used were (90:10:0.2, v/v/v) and (95:5:0.2, v/v/v) combinations of n-heptane-ethanol-diethylamine, respectively. The flow rates were 0.5, 1.0 and 2.0 mL min(-1) with detection at 225 nm. The capacity (k), selectivity (alpha) and resolution (R(s)) factors were 0.44-12.91, 1.12-2.19 and 1.00-9.50, respectively. The proposed supra-molecular models indicated that the chiral resolution were governed by pi-pi interactions, hydrogen bondings and steric effect. PMID:19203609

  17. Gas-chromatographic determination of mexiletine with a nitrogen-selective detector.

    PubMed

    Vasiliades, J; Kellett, J; Cox, R S

    1984-06-01

    The authors present a procedure for the determination of mexiletine in serum. The drugs are extracted under basic conditions into n-heptane/isobutanol (96/4 by vol) and then extracted again into 1 mol/L H2SO4. The acidic solution is made basic with sodium hydroxide, reextracted with diethyl ether, and the extract evaporated. The residue is redissolved in ethanol and analyzed by gas chromatography with a nitrogen-selective detector. By use of two internal standards, diphenhydramine and p- chlorodisopyramide , concentration and instrument response are related linearly from 500 micrograms/L to 4.0 mg/L. Interferences from other drugs also are eliminated by using two internal standards. Within-run precision (CV) was 5% at the 1 and 2 mg/L concentration: between-run precision was 10% and 5% at those respective concentrations. Interference studies indicate that most commonly prescribed basic drugs will not interfere with this procedure. PMID:6731356

  18. The distribution of laudanosine in tissues after death from atracurium injection.

    PubMed

    Kintz, P; Tracqui, A; Ludes, B

    2000-01-01

    A case is presented involving an acute fatality resulting from self-administration of atracurium, a muscle relaxant by a 45-year-old nurse. In the body, atracurium undergoes a spontaneous non-enzymatic degradation to laudanosine and an acrylate moiety. Laudanosine was quantified using gas chromatography coupled to mass spectrometry after extraction with chloroform-isopropanol-n-heptane (50:17:33 v/v) at pH 9.5 and separation on a HP5-MS capillary column. Laudanosine was subject to postmortem redistribution due to release from drug-rich tissues such as the lung and heart. The heart blood (917 ng/ml) to peripheral blood (390 ng/ml) ratio was 2.4. No other drugs, including ethanol were detected. PMID:11197637

  19. Characterizing the migration of antioxidants from polypropylene into fatty food simulants.

    PubMed

    Garde, J A; Catalá, R; Gavara, R; Hernandez, R J

    2001-08-01

    The migration (diffusion and equilibrium) processes of antioxidants (AOs) from polypropylene (PP) films of different thicknesses into n-heptane and 95% ethanol as fatty food simulants were analysed at 20, 37 and 60 degrees C. Heptane fully extracted the AOs from the polymer while a partition equilibrium described the migration to ethanol. The kinetics of migration were also studied via the diffusion coeffcients. As expected, diffusion was found to be faster when the polymer was in contact with heptane, due to polymer swelling by the solvent. The kinetics of the process in ethanol was described by different theoretical expressions which are discussed. Equations disregarding partition equilibrium failed to describe the process and the diffusion coefficient values obtained through them were much smaller than the actual ones and dependent on film thickness. The results also showed the significance of food simulant selection in the analysis of food-packaging interactions and migration variability with thickness. PMID:11469331

  20. Sephadex LH-20 multiple-column chromatography for the simultaneous separation of progesterone, deoxycorticosterone and 17alpha-hydroxyprogesterone from small plasma samples.

    PubMed

    Golder, W A; Sippell, W G

    1976-08-01

    A simple and convenient chromatographic method is described for the simultaneous and complete separation of the unconjugated steroids progesterone, deoxycorticosterone and 17 alpha-hydroxyprogesterone on 40-cm columns of Sephadex LH-20 using a water-saturated solvent system containing n-heptane-chloroform (1:1) plus 0.25% of ethanol. Manual operation of up to ten columns run in parallel is facilitated by the use of graduated, cylindrical, solvent reservoirs on top of the columns. Thus, negligible column-to-column, and only limited day-to-day, variations occur in the elution patterns, and constant high recoveries are obtained. When combined with a previously described 60-cm LH-20 chromatography, eight important corticosteroids can be isolated individually from 16 to 20 small plasma samples per day. PMID:956310

  1. Kinetic analysis of batch ethanol acetylation in isothermal non-stationary multiphase systems by lyophilized mycelium of Aspergillus oryzae.

    PubMed

    Palazzi, Emilio; Molinari, Francesco; Fabiano, Bruno; Pessoa, Adalberto; Converti, Attilio

    2011-01-01

    A relatively complex network of reactions has been investigated, using as a network model the isothermal batch esterification of acetic acid with ethanol in n-heptane catalyzed by lyophilized mycelium of Aspergillus oryzae. The kinetic analysis was firstly carried out on the whole system, without any simplification, by means of the well-known integral method. Owing to the poor results obtained by this way, we developed an alternative approach, combining initial rates and integral analysis and reducing the number of empirical parameters to be determined by the use of equilibrium data. All the values of the parameters calculated according to this "composite" approach to kinetic analysis well correlate with experimental data. PMID:24031645

  2. A mild, rapid, and efficient method of lipid extraction for use in determining vitamin E/lipid ratios.

    PubMed

    Burton, G W; Webb, A; Ingold, K U

    1985-01-01

    A new, general method for lipid extraction and measurement of vitamin E/total lipid ratios in tissue and cell samples has been developed. The new extraction procedure uses a combination of sodium dodecylsulfate, ethanol and n-heptane, and is mild, clean, convenient, efficient and rapid (less than or equal to 5 min). The efficiency of the new method has been confirmed for human plasma, red blood cells and rat liver homogenate by the comparison of the yields of vitamin E, O-acyl lipid and cholesterol with the yields obtained following conventional extraction procedures. Extraction efficiency also has been confirmed for multilamellar vesicles composed of known quantities of vitamin E, egg lecithin and cholesterol. PMID:3968987

  3. Investigations of photochromism of 4-(2',4'-dinitrobenzyl)-pyridine by nanosecond laser absorption spectroscopy

    NASA Astrophysics Data System (ADS)

    Klemm, D.; Klemm, E.; Graness, A.; Kleinschmidt, J.

    1980-05-01

    The photochromism of 4-(2',4'-dinitrobenzyl)-pyridine was investigated by means of laser flash photolysis. Two coloured transients were observed in the spectral ranges of 390-430 nm and 510-590 nm in ethanol and acetonitrile. The first band (390-430 nm, lifetime ? 100-500 ns) is the absorption band of the aci-nitro form and the second band (510-590 nm, lifetime ? 0.5 s) is the absorption band of the polymethine form of 4-(2',4'-dinitrobenzyl)-pyridine. The measurements showed that the lifetime of the aci-nitro form depends on the energy of the laser flash in the case of the acetonitrile solution. Such dependence was not observed in ethanol solution. No short-lived transients were detected in n-heptane solution.

  4. Low-temperature heat pipe experiment package (HEPP) for LDEF (S1001)

    NASA Astrophysics Data System (ADS)

    McIntosh, R., Jr.; Ollendorf, S.; McCreight, C. R.

    1984-02-01

    The principal objectives of the experiment are to determine zero-g start-up performance for conventional and diode low temperature heat pipes, to evaluate heat pipe performance in zero-g for an extended period of time, to determine zero-g transport capability of each heat pipe, and to determine diode operation, including forward conductance, turndown ratio, and transient behavior. Two heat pipes, a fixed conductance transporter heat pipe and a thermal diode heat pipe, are coupled with a radiant cooler system. Both pipes are charged with ethane. Also integrated with the radiator is a phase change material (PCM) canister which provides temperature stability during transport tests. N-heptane, which has a melting/freezing point of 182 K, is used as the PCM. The high heat capacity (28 W-hr of latent heat) provided by the canister permits high power heat pipe testing at constant temperature.

  5. Temperature and velocity profiles in sooting free boundary layer flames

    NASA Technical Reports Server (NTRS)

    Ang, J. A.; Pagni, P. J.; Mataga, T. G.; Margle, J. M.; Lyons, V. J.

    1986-01-01

    Temperature and velocity profiles are presented for cyclohexane, n-heptane, and iso-octane free, laminar, boundary layer, sooting, diffusion flames. Temperatures are measured with 3 mil Pt/Pt-13 percent Rh thermocouples. Corrected gas temperatures are derived by performing an energy balance of convection to and radiation from the thermocouple bead incorporating the variation of air conductivity and platinum emissivity with temperature. Velocities are measured using laser doppler velocimetry techniques. Profiles are compared with previously reported analytic temperature and velocity fields. Comparison of theoretical and experimental temperature profiles suggests improvement in the analytical treatment is needed, which accounts more accurately for the local soot radiation. The velocity profiles are in good agreement, with the departure of the theory from observation partially due to the small fluctuations inherent in these free flows.

  6. Silver nanoparticles in hydrogels and microemulsions—a comparative account of their properties and bio-activity

    NASA Astrophysics Data System (ADS)

    Ray, Debajyoti; Chatterjee, Saptarshi; Sarkar, Keka; De, Swati

    2014-09-01

    Stable silver nanoparticles were prepared in sodium Aerosol OT (AOT) based microemulsions and hydrogels. The various gel and microemulsion compositions used for nanoparticle synthesis were obtained from the phase diagram of the AOT/n-heptane/H2O system. It was found that only in gels can AOT play a dual role of stabilizer as well as reducing agent. In microemulsions, AOT acts as a stabilizer only. In gels, the commonly used NaBH4 reduction results in spherical silver nanoparticles while the AOT based reduction yields highly facetted particles. In microemulsion however, larger particles of undefined shapes are formed in low yield while for the gels, a large number of particles are formed. The synthesized silver nanoparticles show strong antibacterial activity.

  7. Preparation and characterization of polyethylene glycol diacrylate microgels using electron beam radiation

    NASA Astrophysics Data System (ADS)

    Hamzah, Mohd Yusof; Isa, Naurah Mat; Napia, Liyana M. Ali

    2014-02-01

    The use of microemulsion in the development of nanosized gels based on polyethylene glycol diacrylate (PEGDA) is demonstrated. PEGDA was solubilized in n-heptane with use of sodium docusate (AOT) at 0.15M concentration to form reverse micelles. These micelles were than irradiated at 5, 10, 15, 20 and 25 kGy using electron beam (EB) to crosslink the entrapped polymer in the micelles. Ionizing radiation was imparted to the emulsions to generate crosslinking reaction in the micelles formed. The nanosized gels were evaluated in terms of particle diameter using dynamic light scattering (DLS) and the images of the nanosized gels were studied using transmission electron microscopy (TEM). Results show that the size and shape of the particles are influenced by concentration of PEGDA and radiation dose. This study showed that this method can be utilized to produce nanosized gels.

  8. Damköhler number effects on soot formation and growth in turbulent nonpremixed flames

    NASA Astrophysics Data System (ADS)

    Bisetti, Fabrizio; Attili, Antonio; Mueller, Michael E.; Pitsch, Heinz

    2013-11-01

    An analysis of soot formation and growth, based on a set of large simulations of n-heptane/air turbulent nonpremixed combustion, is presented. A detailed chemical mechanism, which includes polycyclic aromatic hydrocarbons, and a high-order method of moments for soot modeling are employed for the first time in the three-dimensional simulation of turbulent sooting flames. The effects of scalar dissipation rate on the soot growth are studied performing three simulations at different Damköhler number while holding the Reynolds number constant. The temperature field is unchanged by the rescaling, due to negligible extinction in all cases. Soot precursors are more sensitive to strain than temperature and their peak concentration decreases by about 40 % and 80 % as the Damköhler number is reduced by a factor of 2 and 4. It is shown that decreasing the Damköhler number does not affect the soot number density, while the soot mass fraction shows a linear dependence on Damköhler number.

  9. DNS of soot formation in three-dimensional turbulent non-premixed jet flames

    NASA Astrophysics Data System (ADS)

    Attili, Antonio; Bisetti, Fabrizio; Mueller, Michael E.; Pitsch, Heinz

    2012-11-01

    A set of three-dimensional Direct Numerical Simulations (DNS) of soot formation in a three-dimensional n-heptane/air turbulent non-premixed jet flame has been performed to investigate the coupling between turbulence, chemistry, and soot dynamics with varying Damköhler number. Finite rate chemistry of Polycyclic Aromatic Hydrocarbons (PAH) is included in the chemistry model. Soot is described with a bivariate distribution in volume-surface sample space, and a selected number of moments of the distribution are transported via a recently proposed transport Lagrangian scheme. Closure of the soot moment equations is achieved via the Hybrid Method of Moments (HMOM). It is observed that, for smaller Damköhler number, the mass fraction of soot particles decreases while the number density stays approximately constant. In addition, Lagrangian statistics are used to study the evolution and transport of soot aggregates during their movement in physical and mixture fraction space.

  10. Supercritical droplet gasification experiments with forced convection

    NASA Technical Reports Server (NTRS)

    Litchford, Ron; Parigger, Chris; Jeng, San-Mou

    1992-01-01

    Preliminary results of a comprehensive experimental program are presented which offer the first direct observations of suspended n-heptane droplet gasifications in pure nitrogen with forced convection without the interference to optical probing associated with a flame. Measurements show attainment of a wet-bulb temperature until reduced pressures exceed about 1.0 under supercritical gas temperatures. Thereafter, temperature measurements indicate fully transient heat-up through the critical temperature. The surface is found to regress in a continuous manner with the measured temperature approaching the critical value at the end of the droplet lifetime under supercritical conditions with very mild level of convection. At increased level of convection for the same ambient conditions, similar sized droplets will undergo significant deformation during the gasification process until partially convected away as a dense vapor cloud as the critical temperature is approached.

  11. Statistical evaluation of the performance of a selective agglomeration process for physical cleaning of Kentucky {number_sign}9 coal

    SciTech Connect

    Kim, S.S.; Morsi, B.I.; Chiang, S.H.

    1994-12-31

    The effects of agglomerant amount, grinding time, slurry pH, and agglomeration time on the Btu recovery and inorganic sulfur rejection of a selective agglomeration process were investigated using Kentucky No. 9 coal. A mixture of n-heptane and a small amount of No. 6 fuel oil was employed as agglomerant. The experimental conditions were selected following a central composite design and regression models were developed to relate the Btu recovery and inorganic sulfur rejection to the operating variables. From the response surfaces constructed with the regression models, it was found that the Btu recovery was poor when the agglomerant/coal weight ratio was lower than 0.3. It was also found that the slurry pH did not have significant effect on the process performances.

  12. A Study of Aircraft Fire Hazards Related to Natural Electrical Phenomena

    NASA Technical Reports Server (NTRS)

    Kester, Frank L.; Gerstein, Melvin; Plumer, J. A.

    1960-01-01

    The problems of natural electrical phenomena as a fire hazard to aircraft are evaluated. Assessment of the hazard is made over the range of low level electrical discharges, such as static sparks, to high level discharges, such as lightning strikes to aircraft. In addition, some fundamental work is presented on the problem of flame propagation in aircraft fuel vent systems. This study consists of a laboratory investigation in five parts: (1) a study of the ignition energies and flame propagation rates of kerosene-air and JP-6-air foams, (2) a study of the rate of flame propagation of n-heptane, n-octane, n-nonane, and n-decane in aircraft vent ducts, (3) a study of the damage to aluminum, titanium, and stainless steel aircraft skin materials by lightning strikes, (4) a study of fuel ignition by lightning strikes to aircraft skins, and (5) a study of lightning induced flame propagation in an aircraft vent system.

  13. Development and Validation of a Reduced Reaction Mechanism for Biodiesel-Fueled Engine Simulations- SAE 2008-01-1378

    SciTech Connect

    Brakora, Jessica L; Ra, Youngchul; Reitz, Rolf; McFarlane, Joanna; Daw, C Stuart

    2008-01-01

    In the present study a skeletal chemical reaction mechanism for biodiesel surrogate fuel was developed and validated for multi-dimensional engine combustion simulations. The reduced mechanism was generated from an existing detailed methyl butanoate oxidation mechanism containing 264 species and 1219 reactions. The reduction process included flux analysis, ignition sensitivity analysis, and optimization of reaction rate constants under constant volume conditions. The current reduced mechanism consists of 41 species and 150 reactions and gives predictions in excellent agreement with those of the comprehensive mechanism. In order to validate the mechanism under biodiesel-fueled engine conditions, it was combined with another skeletal mechanism for n-heptane oxidation. This combined reaction mechanism, ERC-Bio, contains 53 species and 156 reactions, which can be used for diesel/biodiesel blend engine simulations. Biodiesel-fueled engine operation was successfully simulated using the ERC-Bio mechanism.

  14. Physicochemical properties of soybean oil extracted from ?-irradiated soybeans

    NASA Astrophysics Data System (ADS)

    Byun, M. W.; Kang, I. J.; Kwon, J. H.; Hayashi, Y.; Mori, T.

    1995-02-01

    Physicochemical properties of soybean oil extracted from ?-irradiated soybeans (0-10kGy) were investigated. No significant changes were observed in the total lipid content, fatty acid composition, acid value, peroxide value and trans fatty acid content at different irradiation doses. A tendency toward increase induction period was observed as irradiation dose increased. At higher dose levels than 10 kGy, n-hexanal content remarkably increased as dose levels increased, showing the possibility of a chemical index for over-dose irradiation in soybeans.

  15. Physicochemical properties of soybean oil extracted from ?-irradiated soybeans

    NASA Astrophysics Data System (ADS)

    Byun, Myung-Woo; Kang, Il-Jun; Kwon, Joong-Ho; Hayashi, Yukako; Mori, Tomohiko

    1996-02-01

    Physicochemical properties of soybean oil extracted from ?-irradiated soybeans (0-10 kGy) were investigated. No significant changes were observed in the total lipid content, fatty acid composition, acid value, peroxide value and trans fatty acid content at different irradiation doses. A tendency toward increased induction period was observed as irradiation dose increased. At higher dose levels than 10 kGy, n-hexanal increased remarkably as dose levels increased, showing the possibility of a chemical index for over-dose irradiation in soybeans.

  16. Raman spectroscopic studies of the phase transitions in hexane at high pressure.

    PubMed

    Huai, Wang; Haifei, Zheng; Qiang, Sun

    2005-12-01

    Raman spectroscopic study of n-hexane was carried out in a cubic zirconia anvil cell up to approximately 2.0 GPa. Under high pressure, the C-H stretching region of the spectrum at 2850-3000 cm(-1) shows measurable changes in frequency, bandwidth, and intensity. These Raman bands shift towards higher frequencies with increasing pressure. At about 1.4 GPa, phase transition from liquid to solid was induced by compression, as was simultaneously observed with the built-in microscope. PMID:16390589

  17. Excited-state Raman spectroscopy with and without actinic excitation: S{sub 1} Raman spectra of trans-azobenzene

    SciTech Connect

    Dobryakov, A. L.; Quick, M.; Ioffe, I. N.; Granovsky, A. A.; Ernsting, N. P.; Kovalenko, S. A.

    2014-05-14

    We show that femtosecond stimulated Raman spectroscopy can record excited-state spectra in the absence of actinic excitation, if the Raman pump is in resonance with an electronic transition. The approach is illustrated by recording S{sub 1} and S{sub 0} spectra of trans-azobenzene in n-hexane. The S{sub 1} spectra were also measured conventionally, upon n?* (S{sub 0} ? S{sub 1}) actinic excitation. The results are discussed and compared to earlier reports.

  18. Magnetic cellulose-derivative structures

    DOEpatents

    Walsh, Myles A. (Falmouth, MA); Morris, Robert S. (Fairhaven, MA)

    1986-09-16

    Structures to serve as selective magnetic sorbents are formed by dissolving a cellulose derivative such as cellulose triacetate in a solvent containing magnetic particles. The resulting solution is sprayed as a fine mist into a chamber containing a liquid coagulant such as n-hexane in which the cellulose derivative is insoluble but in which the coagulant is soluble or miscible. On contact with the coagulant, the mist forms free-flowing porous magnetic microspheric structures. These structures act as containers for the ion-selective or organic-selective sorption agent of choice. Some sorbtion agents can be incorporated during the manufacture of the structure.

  19. Magnetic cellulose-derivative structures

    DOEpatents

    Walsh, M.A.; Morris, R.S.

    1986-09-16

    Structures to serve as selective magnetic sorbents are formed by dissolving a cellulose derivative such as cellulose triacetate in a solvent containing magnetic particles. The resulting solution is sprayed as a fine mist into a chamber containing a liquid coagulant such as n-hexane in which the cellulose derivative is insoluble but in which the coagulant is soluble or miscible. On contact with the coagulant, the mist forms free-flowing porous magnetic microspheric structures. These structures act as containers for the ion-selective or organic-selective sorption agent of choice. Some sorption agents can be incorporated during the manufacture of the structure. 3 figs.

  20. Socioeconomic and personal behavioral factors affecting children's exposure to VOCs in urban areas in Korea.

    PubMed

    Byun, Hyaejeong; Ryu, Kyongnam; Jang, Kyungjo; Bae, Hyunjoo; Kim, Dongjin; Shin, Hosung; Chu, Jangmin; Yoon, Chungsik

    2010-02-01

    Volatile organic compounds (VOCs) are known to cause adverse health effects. We investigated the relationships between children's VOC exposure and socioeconomic and human activity factors with passive personal samplers, questionnaires, and time-activity diaries (TAD). Statistical analyses were conducted using SAS 9.1, and the results were organized using SigmaPlot 8.0 software. Chemicals such as benzene, toluene, 2-butanone, ethylbenzene, xylene, chloroform, n-hexane, heptane, and some kinds of decanes, which are known to adversely affect public health, were identified in measured samples. These were mainly emitted from outdoor sources (e.g., vehicular traffic) or indoor sources (e.g., household activities such as cooking and cleaning) or both. We concluded that region was the most important socioeconomic factor affecting children's VOC exposure, and the significant compounds were n-hexane (p = 0.006), 1,1,1-trichloroethane (p = 0.001), benzene (p = 0.003), toluene (p = 0.002), ethylbenzene (p = 0.020), m-, p-xylene (p = 0.014), dodecane (p = 0.003), and hexadecane (p = 0.001). Parental education, year of home construction and type of housing were also slightly correlated with personal VOC exposure. Only the concentration of o-xylene (p = 0.027) was significantly affected by the parental education, and the concentrations of benzene (p = 0.030) and 2-butanone (p = 0.049) by the type of housing. Also, tridecane (p = 0.049) and n-hexane (p = 0.033) were significantly associated with the year of home construction. When household activities such as cooking were performed indoors, children's VOC concentrations tended to be higher, especially for n-hexane, chloroform, heptane, toluene (p < 0.05), 1,1,1-trichloroethane, benzene, dodecane, and hexadecane (p < 0.01). However, smoking had a significant effect for only dodecane, and cleaning had no impact on any VOC concentrations. Considering both socioeconomic and personal behavioral factors simultaneously, socioeconomic factors such as region had a greater effect on children's VOC exposures than indoor activities. From this study, we can suggest that socioeconomic factors as well as environmental factors should be considered when formulating environmental policy to protect children's health. PMID:20145896

  1. Viscosity of binary mixtures. IV. Triethylamine with alkanes and monoalkylamines at 303. 15 and 313. 15 K

    SciTech Connect

    Oswal, S.L.; Patel, S.G. )

    1992-09-01

    Viscosities and densities of seven binary mixtures of n-hexane, n-octane, iso-octane, n-propylamine, n-butylamine, n-hexylamine, and n-octylamine with triethylamine have been measured at 303.15 and 313.15 K. Deviations of viscosities from a linear dependence on the mole fraction and values of excess Gibbs energy of activation [delta]G[sup *E] of viscous flow are attributable to the H-bonding and to the size of the alkylamine and alkane molecules. 8 refs., 4 figs., 4 tabs.

  2. Effect of synthetic conditions on the adsorption properties of the resulting offretite-type zeolite

    NASA Astrophysics Data System (ADS)

    Gorshunova, K. K.; Travkina, O. S.; Kapustin, G. I.; Kustov, L. M.; Pavlov, M. L.; Kutepov, B. I.

    2015-05-01

    The effect of the nature of the silicon-containing component of the reaction mixture and that of the crystallization conditions on characteristics of the resulting offretite-type zeolite powder, including its degree of crystallinity, particle-size distribution, and adsorption properties with respect to toluene, cyclohexane, n-hexane, and water molecules, are considered. The thermal desorption of toluene from cationic forms of the offretite-type zeolite is reported. The K-forms of this zeolite can retain adsorbed toluene up to 300-400°C.

  3. Internal Technical Report, Heat Exchanger Sizing for 20 MW Geothermal Power Plants at MX Sites

    SciTech Connect

    Kochan, R.J.; Bliem, C.J.

    1981-12-01

    This report presents the details of the analyses used to size the heaters, steam condenser, and working fluid condenser for a proposed 20 MW geothermal power plant application at MX sites in the southwest. These units would use a mixture of hydrocarbons (90% isobutane--10% n-hexane) to extract energy from moderate temperature resources (resource temperatures of 365 F, 400 F, and 450 F were considered). The working fluid will be maintained at supercritical pressures in the heater units. Studies have shown that this cycle will provide a significant net power increase over standard dual boiling single fluid cycles currently in use, e.g., the Raft River 5 MW pilot plant.

  4. Terpenes as green solvents for extraction of oil from microalgae.

    PubMed

    Dejoye Tanzi, Celine; Abert Vian, Maryline; Ginies, Christian; Elmaataoui, Mohamed; Chemat, Farid

    2012-01-01

    Herein is described a green and original alternative procedure for the extraction of oil from microalgae. Extractions were carried out using terpenes obtained from renewable feedstocks as alternative solvents instead of hazardous petroleum solvents such as n-hexane. The described method is achieved in two steps using Soxhlet extraction followed by the elimination of the solvent from the medium using Clevenger distillation in the second step. Oils extracted from microalgae were compared in terms of qualitative and quantitative determination. No significant difference was obtained between each extract, allowing us to conclude that the proposed method is green, clean and efficient. PMID:22777188

  5. Stepwise fluorination of [MeAlN(2,6-i-Pr2C6H3)]3 using trimethyltin fluoride as fluorinating agent

    E-print Network

    Müller, Peter

    with trimethyltin fluoride in toluene or n-hexane gave only mixtures of several compounds as shown by NMR spectro, trimethyltin fluoride leads to the mono- and difluoro compounds, [FAl(MeAl)2(N(2,6-i-Pr2C6H3))3]Á2THF 2 compound [FAlN(2,6-i-Pr2C6H3)]3Á3THF 4 and [Me2SnN(2,6-i-Pr2C6H3)]2 5 as a by-product. The core of compound

  6. Detonability of hydrocarbon fuels in air

    NASA Technical Reports Server (NTRS)

    Beeson, H. D.; Mcclenagan, R. D.; Bishop, C. V.; Benz, F. J.; Pitz, W. J.; Westbrook, C. K.; Lee, J. H. S.

    1991-01-01

    Studies were conducted of the detonation of gas-phase mixtures of n-hexane and JP-4, with oxidizers as varied as air and pure oxygen, measuring detonation velocities and cell sizes as a function of stoichiometry and diluent concentration. The induction length of a one-dimensional Zeldovich-von Neumann-Doering detonation was calculated on the basis of a theoretical model that employed the reaction kinetics of the hydrocarbon fuels used. Critical energy and critical tube diameter are compared for a relative measure of the heavy hydrocarbon fuels studied; detonation sensitivity appears to increase slightly with increasing carbon number.

  7. Speed of sound and isentropic compressibilities of nonelectrolyte liquid mixtures. I. Binary mixtures containing p-dioxane

    SciTech Connect

    Oswal, S.L.; Phalak, R.P. )

    1993-01-01

    The speed of sound was measured for mixtures of p-dioxane with cyclohexane, n-hexane, benzene, toluene, carbon tetrachloride, chloroform, 1,1,2,2-tetrachloroethane, pentachloroethane, and ethyl acetate over the whole mole fraction range at 30[degrees]C. These data were combined with densities and molar volumes to obtain isentropic compressibilities and Rao's molar sound functions. Excess isentropic compressibilities and excess speeds of sound have also been calculated. The behavior of the present mixtures is discussed in terms of possible molecular interactions and the Prigogine-Flory-Patterson theory of liquid mixtures.

  8. Determination by gas-liquid chromatography of trace amounts of soft polyvinyl chloride plastic additives in aqueous solutions. I. Epoxidized vegetable oils.

    PubMed

    Smistad, G; Waaler, T; Roksvaag, P O

    1989-01-01

    A gas-liquid chromatographic method for the determination of epoxidized vegetable oils (EVO), such as epoxidized soybean oil and epoxidized linseed oil, in aqueous solutions is described. The EVOs are extracted with n-hexane and transesterified to the methyl esters by sodium methoxide in methanol. 3% OV-210 is used as the stationary phase. The weakest standard solution corresponds to 5 micrograms/l (5 ppb) of EVO in an aqueous sample. The reproducibility of a single analysis is 5%. The method is used for the determination of EVO in intravenous fluids stored in flexible polyvinyl chloride bags. PMID:2597333

  9. Electronic spectra and excited-state dynamics of 4-fluoro-N,N-dimethylaniline

    NASA Astrophysics Data System (ADS)

    Fujiwara, Takashige; Reichardt, Christian; Aaron Vogt, R.; Crespo-Hernández, Carlos E.; Zgierski, Marek Z.; Lim, Edward C.

    2013-10-01

    Concerted ultrafast time-resolved spectroscopic experiments and ab initio computational (TDDFT) studies of the electronic transitions of 4-fluoro-N,N-dimethylaniline (FDMA) have been performed to investigate the mechanism of photo-induced intramolecular charge transfer (ICT). The compound FDMA shows dual fluorescence from a ??? state and a closely-lying twisted intramolecular charge transfer (TICT) state in both n-hexane and acetonitrile. The very similar lifetimes observed for the two emission bands indicate that the ??? and the TICT states are effectively in thermal equilibrium at room temperature.

  10. A computational investigation of diesel and biodiesel combustion and NOx formation in a light-duty compression ignition engine

    SciTech Connect

    Wang, Zihan; Srinivasan, Kalyan K.; Krishnan, Sundar R.; Som, Sibendu

    2012-04-24

    Diesel and biodiesel combustion in a multi-cylinder light duty diesel engine were simulated during a closed cycle (from IVC to EVO), using a commercial computational fluid dynamics (CFD) code, CONVERGE, coupled with detailed chemical kinetics. The computational domain was constructed based on engine geometry and compression ratio measurements. A skeletal n-heptane-based diesel mechanism developed by researchers at Chalmers University of Technology and a reduced biodiesel mechanism derived and validated by Luo and co-workers were applied to model the combustion chemistry. The biodiesel mechanism contains 89 species and 364 reactions and uses methyl decanoate, methyl-9- decenoate, and n-heptane as the surrogate fuel mixture. The Kelvin-Helmholtz and Rayleigh-Taylor (KH-RT) spray breakup model for diesel and biodiesel was calibrated to account for the differences in physical properties of the fuels which result in variations in atomization and spray development characteristics. The simulations were able to capture the experimentally observed pressure and apparent heat release rate trends for both the fuels over a range of engine loads (BMEPs from 2.5 to 10 bar) and fuel injection timings (from 0���° BTDC to 10���° BTDC), thus validating the overall modeling approach as well as the chemical kinetic models of diesel and biodiesel surrogates. Moreover, quantitative NOx predictions for diesel combustion and qualitative NOx predictions for biodiesel combustion were obtained with the CFD simulations and the in-cylinder temperature trends were correlated to the NOx trends."

  11. Integrated investigations of the electrosurface properties of nonaqueous disperse and capillary systems.

    PubMed

    Zhukov, A N

    2007-10-31

    Survey of the experimental results obtained in the Department of Colloid Chemistry of St. Petersburg State University on the integrated investigations of the electrosurface properties of various nonaqueous disperse and capillary systems covering a wide range of electrolyte solutions in various organic solvents: amphoteric ethanol and 1-butanol; dipolar aprotic dimethylsulfoxide, dimethylformamide, acetone and nitromethane; nonpolar n-heptane in contact with SiO2, TiO2, Al2O3 and glass. Electrokinetic potential zeta and charge sigma(zeta), adsorption of ions Gamma, surface conductivity Ks of powdery silica, titania and alumina were determined depending on the concentration 10(-5)-10(-2) M of LiBr, KBr, NaBr, CsBr, HBr, NaCl, NaOH, HCl, various tetraalkylammonium bromides and ionic surfactants in the above cited solvents. Special attention was paid to the consistency of the results of zeta-potential evaluation obtained from the streaming potential and electrophoretic mobility data using the most commonly known theoretical expressions. It was shown that the surface conductivity must be taken into account in all cases for the evaluation of correct zeta-potential values. The surface conductivity and zeta-potential for the porous quartz plugs and glass membranes were determined as the functions of concentration of the anionic surfactants in n-heptane containing controlled traces of water. It was also shown that in the cases of the less polar solvents and more polar solids the enormous values of surface conductivity are due to the adsorption of the traces of water and in the cases of more hydrophylic liquids due to the overall adsorption of all ionic components from the solutions. PMID:17543873

  12. SPME-GC determination of potential volatile organic leachables in aqueous-based pharmaceutical formulations packaged in overwrapped LDPE vials.

    PubMed

    Akapo, Samuel O; McCrea, Chithra M

    2008-07-15

    A direct liquid immersion solid-phase microextraction-gas chromatographic (SPME-GC) method was developed and validated for the determination of 11 potential volatile organic compounds that may leach from preprinted foil laminate overwrap into aqueous pharmaceutical formulations filled in low-density polyethylene (LDPE) vials. The target compounds namely, ethanol, acetone, isopropyl alcohol, ethyl acetate, 2-butanone, n-heptane, isopropyl acetate, n-propyl acetate, toluene, diacetone alcohol and 1-propoxy-2-propanol, were suitably extracted from aqueous sample solutions by SPME using a 100-microm PDMS fiber, desorbed inside the GC inlet port, and analyzed using a J&W Scientific DB-1701 (86% polydimethylsiloxane/14% cyanopropylphenyl, 30 m x 0.53 mm i.d., 1.5-microm film thickness) capillary column with FID detection. The variables affecting the SPME absorption and desorption conditions were optimized and discussed. The average recoveries for all analytes varied from about 97.9 to 116.7% with the exception of n-heptane and toluene where the mean recoveries ranged from about 73.6 to 100.0% presumably due to their poor solubility in the aqueous sample matrix. The standard curves for all compounds were linear over the concentration range investigated with coefficient of correlations, r(2)> or =0.98. The detection and quantitation limits ranged from approximately 0.6 ng/ml to 1.7 microg/ml and 5 ng/ml to 4.2 microg/ml, respectively, and the intra- and inter-day precision was considered adequate (R.S.D.< or =16%) for low-level determination of the target analytes in the sample matrix. The method was successfully applied for determination of the target compounds from preprinted foil laminate overwrap in selected aqueous-based pharmaceutical formulations. PMID:18372139

  13. [Enantiomeric separation of trantinterol hydrochloride by high performance liquid chromatography on cellulose derivative-based chiral stationary phase].

    PubMed

    Jiang, Minyan; Qin, Feng; Xiong, Zhili; Zhang, Shangshang; Pan, Li; Li, Famei

    2011-11-01

    A high performance liquid chromatographic (HPLC) method using cellulose tris-(3,5-dimethylphenylcarbamate) as chiral stationary phase (Lux Cellulose-1) for the separation of trantinterol hydrochloride enantiomers was developed. The method was based on normal phase model with n-heptane as the basal solvent of mobile phase. The influences of organic modifiers, mobile phase additives and column temperature on the retention and separation of the enantiomers were examined and discussed. It was demonstrated that the mobile phase additives had a dominant effect on the enantiomeric separation. No separation was observed with the addition of diethylamine only in the mobile phase, while the retention was increased and the enatiomeric separation was observed with the addition of trifluoroacetic acid. When both trifluoroacetic acid and diethylamine were added into the mobile phase, the enantioseparation was significantly improved with a resolution up to 4.0. Ethanol and isopropanol were investigated as the organic modifiers, and ethanol offered a better enatiomeric resolution for trantinterol hydrochloride. In the examined temperature range between 15 degrees C and 35 degrees C both separation factor and resolution were decreased with the increase of the column temperature. The optimized chiral HPLC method for the separation of trantinterol hydrochloride enantiomers involved a Lux Cellulose-1 column (250 mm x 4.6 mm, 5 microm), a mobile phase of n-heptane/ethanol/trifluoroacetic acid/diethylamine (88: 12: 0.3: 0.05, v/v/v/v) at a flow rate of 1.0 mL/min, a detection at 246 nm and a column temperature of 25 degrees C. The method is simple and rapid for the enantiomeric impurity determination of (-)-trantinterol hydrochloride bulk samples. PMID:22393706

  14. Mapping surrogate gasoline compositions into RON/MON space

    SciTech Connect

    Morgan, Neal; Kraft, Markus; Smallbone, Andrew; Bhave, Amit; Cracknell, Roger; Kalghatgi, Gautam

    2010-06-15

    In this paper, new experimentally determined octane numbers (RON and MON) of blends of a tri-component surrogate consisting of toluene, n-heptane, i-octane (called toluene reference fuel TRF) arranged in an augmented simplex design are used to derive a simple response surface model for the octane number of any arbitrary TRF mixture. The model is second-order in its complexity and is shown to be more accurate to the standard ''linear-by-volume'' (LbV) model which is often used when no other information is available. Such observations are due to the existence of both synergistic and antagonistic blending of the octane numbers between the three components. In particular, antagonistic blending of toluene and iso-octane leads to a maximum in sensitivity that lies on the toluene/iso-octane line. The model equations are inverted so as to map from RON/MON space back into composition space. Enabling one to use two simple formulae to determine, for a given fuel with known RON and MON, the volume fractions of toluene, n-heptane and iso-octane to be blended in order to emulate that fuel. HCCI engine simulations using gasoline with a RON of 98.5 and a MON of 88 were simulated using a TRF fuel, blended according to the derived equations to match the RON and MON. The simulations matched the experimentally obtained pressure profiles well, especially when compared to simulations using only PRF fuels which matched the RON or MON. This suggested that the mapping is accurate and that to emulate a refinery gasoline, it is necessary to match not only the RON but also the MON of the fuel. (author)

  15. Procedure for and results of simultaneous determination of aromatic hydrocarbons and fatty acid methyl esters in diesel fuels by high performance liquid chromatography.

    PubMed

    Kami?ski, M; Gilgenast, E; Przyjazny, A; Romanik, G

    2006-07-28

    The content of aromatic hydrocarbons in diesel fuels is regulated by appropriate standards, and a further reduction in the allowed concentration of these hazardous substances in these fuels is expected. The content of aromatic hydrocarbons in diesel fuels is most often determined using standard methods EN-12916 or ASTM D-6591. The content of polycyclic aromatic hydrocarbons (PAHs) is determined from a single peak obtained using normal phase high-performance liquid chromatography (NP-HPLC), a column of the NH2 type, n-heptane as the eluent, refractive index detector (RID) and backflushing of the eluent. However, the methods mentioned above cannot be applied when the fuel contains fatty acid methyl esters (FAME), which lately has become more common. The content of FAME in diesel oils is determined using mid-IR spectrophotometry based on the absorption of carbonyl group. However, no standard procedure for the determination of classes of aromatic hydrocarbons in diesel fuels containing FAME is yet available. The present work describes such a modification of methods EN-12916/ASTM D-6591 that provides a simultaneous determination of individual groups of aromatic hydrocarbons, total content of polycyclic aromatic hydrocarbons and the FAME content in diesel fuels. The refractive index detector (RID) and n-heptane as the mobile phase are still used, but backflushing of the eluent is applied after the elution of all polycyclic aromatic hydrocarbons. Additionally, ultraviolet diode array detection is used for the exact determination of low contents of polycyclic aromatic hydrocarbons and to confirm the presence of FAME in the analyzed fuel. PMID:16704869

  16. Direct observation of breaking of the intramolecular H-bond, and slowing down of the proton motion and tuning its mechanism in an HBO derivative.

    PubMed

    Alarcos, Noemí; Gutiérrez, Mario; Liras, Marta; Sánchez, Félix; Moreno, Miquel; Douhal, Abderrazzak

    2015-06-14

    We report on spectroscopic and photodynamical behaviours of 5-amino-2-(2'-hydroxyphenyl)benzoxazole (5A-HBO) in different solutions. The dye undergoes an ultrafast ICT reaction (<50 fs) (comparable to that observed for its methylated derivative, 5A-MBO), in agreement with the results of TD-DFT theoretical calculations (gas phase). Depending on the used solvent, the ICT reaction can be followed by a reversible/irreversible excited-state intramolecular proton transfer (ESIPT) reaction or by breaking of the intramolecular hydrogen bond (IHB). 5A-HBO in n-heptane solution exhibits an irreversible and slow (20 ps) ESIPT reaction, while that of the parent compound, HBO, takes place in less than 150 fs. Compared to excited HBO behaviour, theoretical calculations on 5A-HBO suggest a higher energy barrier (?4 kcal mol(-1)) between the relaxed enol and keto tautomers, in addition to a less stabilization of the latter, which is in agreement with experiments in n-heptane. On the other hand, in dichloromethane, after the ICT reaction a subsequent and reversible proton motion occurs in an extraordinary slower regime (ns-time scale). No isotopic effect (OH/OD exchange) was observed in this solvent reflecting that the reversible ESIPT reaction evolves along the IHB and solvent coordinates. Using tetrahydrofurane and acetonitrile, we observed a breaking of the IHB due to specific intermolecular interactions with solvent molecules. This leads to the formation of open-enol forms, which undergo an ICT reaction as it occurs in 5A-MBO. These results bring new findings in the coupled ICT and ESIPT reactions. The photobehaviour of this new dye remarkably changes with the solvent nature, opening up the window for further research and possible applications in sensing polarity or H-bonding of media similar to that of the biological ones. PMID:25966780

  17. Vaporization modeling of petroleum-biofuel drops using a hybrid multi-component approach

    SciTech Connect

    Zhang, Lei; Kong, Song-Charng

    2010-11-15

    Numerical modeling of the vaporization characteristics of multi-component fuel mixtures is performed in this study. The fuel mixtures studied include those of binary components, biodiesel, diesel-biodiesel, and gasoline-ethanol. The use of biofuels has become increasingly important for reasons of environmental sustainability. Biofuels are often blended with petroleum fuels, and the detailed understanding of the vaporization process is essential to designing a clean and efficient combustion system. In this study, a hybrid vaporization model is developed that uses continuous thermodynamics to describe petroleum fuels and discrete components to represent biofuels. The model is validated using the experimental data of n-heptane, n-heptane-n-decane mixture, and biodiesel. Since biodiesel properties are not universal due to the variation in feedstock, methods for predicting biodiesel properties based on the five dominant fatty acid components are introduced. Good levels of agreement in the predicted and measured drop size histories are obtained. Furthermore, in modeling the diesel-biodiesel drop, results show that the drop lifetime increases with the biodiesel concentration in the blend. During vaporization, only the lighter components of diesel fuel vaporize at the beginning. Biodiesel components do not vaporize until some time during the vaporization process. On the other hand, results of gasoline-ethanol drops indicate that both fuels start to vaporize once the process begins. At the beginning, the lighter components of gasoline have a slightly higher vaporization rate than ethanol. After a certain time, ethanol vaporizes faster than the remaining gasoline components. At the end, the drop reduces to a regular gasoline drop with heavier components. Overall, the drop lifetime increases as the concentration of ethanol increases in the drop due to the higher latent heat. (author)

  18. Bottom-up derivation of conservative and dissipative interactions for coarse-grained molecular liquids with the conditional reversible work method

    SciTech Connect

    Deichmann, Gregor; Marcon, Valentina; Vegt, Nico F. A. van der

    2014-12-14

    Molecular simulations of soft matter systems have been performed in recent years using a variety of systematically coarse-grained models. With these models, structural or thermodynamic properties can be quite accurately represented while the prediction of dynamic properties remains difficult, especially for multi-component systems. In this work, we use constraint molecular dynamics simulations for calculating dissipative pair forces which are used together with conditional reversible work (CRW) conservative forces in dissipative particle dynamics (DPD) simulations. The combined CRW-DPD approach aims to extend the representability of CRW models to dynamic properties and uses a bottom-up approach. Dissipative pair forces are derived from fluctuations of the direct atomistic forces between mapped groups. The conservative CRW potential is obtained from a similar series of constraint dynamics simulations and represents the reversible work performed to couple the direct atomistic interactions between the mapped atom groups. Neopentane, tetrachloromethane, cyclohexane, and n-hexane have been considered as model systems. These molecular liquids are simulated with atomistic molecular dynamics, coarse-grained molecular dynamics, and DPD. We find that the CRW-DPD models reproduce the liquid structure and diffusive dynamics of the liquid systems in reasonable agreement with the atomistic models when using single-site mapping schemes with beads containing five or six heavy atoms. For a two-site representation of n-hexane (3 carbons per bead), time scale separation can no longer be assumed and the DPD approach consequently fails to reproduce the atomistic dynamics.

  19. Influence of activated carbon characteristics on toluene and hexane adsorption: Application of surface response methodology

    NASA Astrophysics Data System (ADS)

    Izquierdo, Mª Teresa; de Yuso, Alicia Martínez; Valenciano, Raquel; Rubio, Begoña; Pino, Mª Rosa

    2013-01-01

    The objective of this study was to evaluate the adsorption capacity of toluene and hexane over activated carbons prepared according an experimental design, considering as variables the activation temperature, the impregnation ratio and the activation time. The response surface methodology was applied to optimize the adsorption capacity of the carbons regarding the preparation conditions that determine the physicochemical characteristics of the activated carbons. The methodology of preparation produced activated carbons with surface areas and micropore volumes as high as 1128 m2/g and 0.52 cm3/g, respectively. Moreover, the activated carbons exhibit mesoporosity, ranging from 64.6% to 89.1% the percentage of microporosity. The surface chemistry was characterized by TPD, FTIR and acid-base titration obtaining different values of surface groups from the different techniques because the limitation of each technique, but obtaining similar trends for the activated carbons studied. The exhaustive characterization of the activated carbons allows to state that the measured surface area does not explain the adsorption capacity for either toluene or n-hexane. On the other hand, the surface chemistry does not explain the adsorption results either. A compromise between physical and chemical characteristics can be obtained from the appropriate activation conditions, and the response surface methodology gives the optimal activated carbon to maximize adsorption capacity. Low activation temperature, intermediate impregnation ratio lead to high toluene and n-hexane adsorption capacities depending on the activation time, which a determining factor to maximize toluene adsorption.

  20. Mechanical properties improvement of silica aerogel through aging: Role of solvent type, time and temperature

    NASA Astrophysics Data System (ADS)

    Omranpour, H.; Dourbash, A.; Motahari, S.

    2014-05-01

    Effective parameters that enhance mechanical properties during aging were investigated in the present study. Silica aerogels were made from tetraethyl orthosilicate (TEOS), water, methanol and NH4F in molar ratio 1:4:8:2×10-3 using a one-step method. Different time, temperature and aging solvents in aging stage were studied. Subsequently, solvent exchange with n-hexane, modification under TMCS solution and ambient pressure drying (APD) were performed for all samples. The aerogels had densities within the range of 0.1 and 0.6 g/cm3. The FTIR, mechanical properties, density and BET results, porosity, pore volume, pore diameter and surface area of the samples, were discussed. The compression properties of the gel increased with the increase in the time and temperature of aging. It was observed that solvents with more polarity improved polymerization, which enhanced the mechanical properties of the related samples. However, the stresses and capillary forces of water during drying were so large that inhibited "spring-back effect" during APD, and consequently a collapsed silica network with higher density was fabricated. In other words, the specific compression strength and modulus declined drastically. For methanol, alcohols inhibit the reactions inconveniently causing more shrinkage. In aging by n-hexane, capillary pressure declined significantly and thereby shrinkage was eliminated and silica aerogels with low bulk densities (0.095 g/cm3), high specific surface areas (600 m2/g), and large pore volumes (2.6 cm3/g) were synthesized.

  1. Comprehensive assessment of phenolics and antiradical potential of Rumex hastatus D. Don. roots

    PubMed Central

    2014-01-01

    Background Roots of Rumex hastatus (Polygonaceae) are traditionally used for the treatment of various ailments including liver and lung diseases. In this study, various solvent extracts of R. hastatus roots, like methanolic, n-hexane, ethyl acetate, chloroform, butanol and aqueous fractions were assessed through their antioxidant properties in vitro and determination of phenolic contents. Methods Several parameters like DPPH?, ABTS?+, ?OH, H2O2, superoxide free radical scavenging, iron chelating power, reducing power, ?-carotene bleaching power, antioxidant capacity and total phenolics and flavonoids were evaluated. High Performance liquid Chromatography (HPLC) was also considered. Results Though all the fractions exhibited dose dependant activity. The samples with the highest activity were the butanol and methanol fractions in all the assays except hydrogen peroxide radical scavenging assay where chloroform fraction showed the highest scavenging aptitude. On the other hand, aquous fraction showed significant beta carotene linoleic acid, while n-hexane and ethyl acetate fractions exhibited a lesser antioxidant activity in all the assays. HPLC revealed the presence of rutin, luteolin-7-glucoside, vitexin and luteolin. Conclusion These results have to some extent substantiated the use of R. hastatus roots against different diseases, as an excellent basis of potential antioxidant due to the presence of sufficient amount of phenolics such as rutin and luteolin. PMID:24507200

  2. Histological investigation of the effect of soybean (Glycine max) extracts on the collagen layer and estrogen receptors in the skin of female rats

    PubMed Central

    Uyar, Belkiz; Sivrikoz, Oya Nermin; Ozdemir, Ugur; Dasbasi, Teslima; Sacar, Handan

    2014-01-01

    OBJECTIVES: The purpose of this study was to analyze the effects of soybean extracts obtained using different extraction methods on the skin of female rats. METHOD: A total of 64 female Sprague-Dawley rats were divided into 8 equal groups. Various extracts were administered to the female rats by oral gavage for one month. The groups comprised carboxymethyl cellulose-free control, carboxymethyl cellulose-plus control, 100-mg/kg n-hexane extract, 200-mg/kg n-hexane extract, 100-mg/kg ethyl acetate extract, 200-mg/kg ethyl acetate extract, 100-mg/kg ethanol extract and 200-mg/kg ethanol extract groups. The thickness of the collagen layer and the number of estrogen receptor-positive cells were evaluated. RESULTS: All the extract-treated groups showed a statistically significant decrease in the number of estrogen receptor-positive cells compared with the control groups. Regarding the thickness of the collagen layer, only the 200-mg/kg ethyl acetate extract-treated group showed a significant increase compared with the control groups (p<0.05). CONCLUSIONS: Our data suggest that oral intake of three different total soybean extracts might have positive estrogenic effects on the skin and that only a high-dose ethyl acetate extract can increase the expression of collagen, which may prove to be beneficial for postmenopausal facial skin. PMID:25627999

  3. Fractionation of technical octabromodiphenyl ether by countercurrent chromatography combined with gas chromatography/mass spectrometry and offline and online (1)H nuclear magnetic resonance spectroscopy.

    PubMed

    Hammann, Simon; Conrad, Jürgen; Vetter, Walter

    2015-06-12

    Countercurrent chromatography (CCC) is a technique, which uses two immiscible liquid phases for a separation process in a long and hollow tube. The technique allows the separation of high amounts of sample (50mg to several grams) with a low consumption of solvents. In this study, we fractionated 50mg technical octabromodiphenyl ether (DE-79) and analyzed the fractions by gas chromatography with mass spectrometry (GC/MS) and proton nuclear magnetic resonance ((1)H NMR) spectroscopy. CCC separations were performed with n-hexane/acetonitrile as solvent system in tail-to-head (i.e. the upper phase is mobile) mode. Twelve CCC fractions were studied for the PBDE composition. CCC elution of PBDE congeners was dependent both on the degree of bromination and substitution pattern. Higher brominated congeners eluted faster than lower brominated congeners and isomers with vicinal hydrogen atoms eluted last. In addition to several known PBDE congeners in DE-79, we were able to unequivocally identify BDE 195 in DE-79 and we could verify the presence of BDE 184. Finally, we also established the online hyphenation of CCC with (1)H NMR. The use of deuterated solvents could be avoided by using n-hexane/acetonitrile as two-phase system. By online CCC-(1)H NMR in stop-flow mode we were able to detect eight PBDE congeners in the mixture. PMID:25913330

  4. Effect of solvent on absorption spectra of all-trans-{beta}-carotene under high pressure

    SciTech Connect

    Liu, W. L.; Zheng, Z. R.; Liu, Z. G.; Zhu, R. B.; Wu, W. Z.; Li, A. H.; Yang, Y. Q.; Dai, Z. F.; Su, W. H.

    2008-03-28

    The absorption spectra of all-trans-{beta}-carotene in n-hexane and carbon disulfide (CS{sub 2}) solutions are measured under high pressure at ambient temperature. The common redshift and broadening in the spectra are observed. Simulation of the absorption spectra was performed by using the time-domain formula of the stochastic model. The pressure dependence of the 0-0 band wavenumber is in agreement with the Bayliss theory at pressure higher than 0.2 GPa. The deviation of the linearity at lower pressure is ascribed to the reorientation of the solvent molecules. Both the redshift and broadening are stronger in CS{sub 2} than that in n-hexane because of the more sensitive pressure dependence of dispersive interactions in CS{sub 2} solution. The effect of pressure on the transition moment is explained with the aid of a simple model involving the relative dimension, location, and orientation of the solute and solvent molecules. The implication of these results for light-harvesting functions of carotenoids in photosynthesis is also discussed.

  5. Optimization of extraction of high purity all-trans-lycopene from tomato pulp waste.

    PubMed

    Poojary, Mahesha M; Passamonti, Paolo

    2015-12-01

    The aim of this work was to optimize the extraction of pure all-trans-lycopene from the pulp fractions of tomato processing waste. A full factorial design (FFD) consisting of four independent variables including extraction temperature (30-50 °C), time (1-60 min), percentage of acetone in n-hexane (25-75%, v/v) and solvent volume (10-30 ml) was used to investigate the effects of process variables on the extraction. The absolute amount of lycopene present in the pulp waste was found to be 0.038 mg/g. The optimal conditions for extraction were as follows: extraction temperature 20 °C, time 40 min, a solvent composition of 25% acetone in n-hexane (v/v) and solvent volume 40 ml. Under these conditions, the maximal recovery of lycopene was 94.7%. The HPLC-DAD analysis demonstrated that, lycopene was obtained in the all-trans-configuration at a very high purity grade of 98.3% while the amount of cis-isomers and other carotenoids were limited. PMID:26041168

  6. The investigation on phytochemicals from Ferulago angulata (Schlecht) Boiss, indigenous to central parts of Iran.

    PubMed

    Razavi, Seyed Mehdi; Ravansalar, Ameneh; Mirinejad, Shahabeddin

    2015-01-01

    Ferulago angulata (Schlecht) Boiss (Apiaceae) is a perennial herb distributed in the central parts of Iran. In this work, the essential oil of Ferulago angulata aerial parts collected from the central parts of Iran was obtained by using hydrodistillation analysed by GC and GC-MS. Air-dried and powdered plant roots were extracted with n-hexane, dichloromethane and methanol, respectively, using a Soxhlet apparatus. The n-hexane extract was subjected to preparative thin-layer chromatography using chloroform-acetone (95:5) as solvent system to yield two linear furanocoumarins, prantschimgin and oxypeucedanin. The structure of theisolated compounds was elucidated by using spectroscopic data such as (1)H NMR, (13)C NMR, UV and IR. The results of GC-MS analyses showed that ?-terpinolene (11.97%), ?-pinene (10.00%), sabinene (6.89%), linalool (5.56%) and cis-ocimene (4.41%) were the main components among 51 constituents characterised in the oil. The oil exhibits considerable phytotoxic activity. PMID:25743037

  7. Cytotoxic and phytotoxic actions of Heliotropium strigosum.

    PubMed

    Shah, Syed Majid; Hussain, Sajid; Khan, Arif-Ullah; Shah, Azhar-Ul-Haq Ali; Khan, Haroon; Ullah, Farhat; Barkatullah

    2015-05-01

    This study describes the cytotoxic and phytotoxic activities of the crude extract of Heliotropium strigosum and its resultant fractions. In brine shrimp toxicology assays, profound cytotoxicity was displayed by ethyl acetate (LD50 8.3 ?g/ml) and chloroform (LD50 8.8 ?g/ml) fractions, followed by relatively weak crude methanolic extract of H. strigosum (LD50 909 ?g/ml) and n-hexane fraction (LD50 1000 ?g/ml). In case of phytotoxicity activity against Lemna acquinoctialis, highest phytotoxic effect was showed by ethyl acetate fraction (LD50 91.0 ?g/ml), while chloroform fraction, plant crude extract and n-hexane, respectively, caused 50%, 30.76 ± 1.1% and 30.7 ± 1.1% inhibitory action at maximum concentration used, that is, 1000 ?g/ml. These data indicates that H. strigosum exhibits cytotoxic and phytotoxic potential, which explore its use as anticancer and herbicidal medicine. The ethyl acetate and chloroform fractions were more potent for the evaluated toxicity effects, thus recommended for isolation and identification of the active compounds. PMID:23406958

  8. Coordination-Driven Self-Assembly of Carbazole-Based Metallodendrimers with Generation-Dependent Aggregation-Induced Emission Behavior.

    PubMed

    Fan, Wen-Jia; Sun, Bin; Ma, Jianqiu; Li, Xiaopeng; Tan, Hongwei; Xu, Lin

    2015-09-01

    A new family of 120° carbazole-based dendritic donors D1-D3 have been successfully designed and synthesized, from which a series of novel supramolecular carbazole-based metallodendrimers with well-defined shapes and sizes were successfully prepared by [2+2] and [3+3] coordination-driven self-assembly. The structures of newly designed rhomboidal and hexagonal metallodendrimers were characterized by multinuclear NMR ((1) H and (31) P) spectroscopy, ESI-TOF mass spectrometry, FTIR spectroscopy, and the PM6 semiempirical molecular orbital method. The fluorescence emission behavior of ligands D1-D3, rhomboidal metallodendrimers R1-R3, and hexagonal metallodendrimers H1-H3 in mixtures of dichloromethane and n-hexane with different n-hexane fractions were investigated. The results indicated that D1-D3 featured typical aggregation-induced emission (AIE) properties. However, different from ligands D1-D3, metallodendrimers R1-R3 and H1-H3 presented interesting generation-dependent AIE properties. Furthermore, evidence for the aggregation of these metallodendrimers was confirmed by a detailed investigation of dynamic light-scattering, Tyndall effect, and SEM. This research not only provides a highly efficient strategy for constructing carbazole-based dendrimers with well-defined shapes and sizes, but also presents a new family of carbazole-based dendritic ligands and rhomboidal and hexagonal metallodendrimers with interesting AIE properties. PMID:26214754

  9. Inhibitory effects of Olea ferruginea crude leaves extract against some bacterial and fungal pathogen.

    PubMed

    Amin, Adnan; Khan, Muhammad Ayaz; Shah, Swahid; Ahmad, Mushatq; Zafar, Muhammad; Hameed, Abdul

    2013-03-01

    This work aimed to evaluate the inhibitory effects of Olea ferruginea crude leaves extract that are commonly used as remedy to cure infections in the tribal (Khyber Agency) areas of Pakistan against some of bacterial and fungal pathogens. The crude n-hexane fraction was appreciably active against both gram positive and negative microorganisms (MIC ranged from 7.5 to 15 mg/ml) followed by butanol fraction (MIC 15 to 30 mg/ml). Conversely least biological activity was shown by chloroform (30mg/ml) and methanol (15 to 30mg/ml) crude fractions. The MBC observed for all crude fractions was same or 2 times higher when compared with MIC for all crude extract fractions. Likewise all the fractions showed activity against Aspergillus niger and maximum zones of inhibition were shown by the n-hexane fraction (14 ± (0.02), butanol (13 ± (0.02) followed by methanol (9 ± (0.05) and chloroform fractions (7 ± (0.02). These results clearly imitate the antibacterial and antifungal potential of Olea ferruginea and hence we recommend the whole plant for further futuristic studies. PMID:23455192

  10. Extraction and GC determination of volatile aroma compounds from extracts of three plant species of the Apiaceae family

    NASA Astrophysics Data System (ADS)

    Stan, M.; Soran, M. L.; Varodi, C.; Lung, I.; Copolovici, L.; M?ruţoiu, C.

    2013-11-01

    Parsley (Petroselinum crispum), dill (Anethum graveolens) and celery (Apium graveolens), three aromatic plants belonging to the Apiaceae (Umbelliferae) botanical family, were selected as sources of essential or volatile oils. Essential oils are composed of a large diversity of volatile aroma compounds. Plant-derived essential oils and extracts have long been used as natural agents in food preservation, pharmaceuticals and medicinal therapies. In the present study, the plant extracts from leaves of parsley, dill and celery, were obtained by maceration, ultrasound-assisted extraction and microwave-assisted extraction. All extractions were performed at 30°C, using different solvents (ethanol, diethyl ether, n-hexane) and solvent mixtures (1:1, v/v). The most effective solvent system for the extraction of volatile aroma compounds was diethyl ether - n-hexane (1:1, v/v). Extraction efficiency and determination of aroma volatiles were performed by GC-FID and GC-MS, respectively. The major volatile compounds present in plant extracts were myristicin, ?-phellandrene, ?-phellandrene, 1,3,8-p-menthatriene, apiol, dill ether and allyl phenoxyacetate.

  11. Ethnobotanical and antimicrobial study of some selected medicinal plants used in Khyber Pakhtunkhwa (KPK) as a potential source to cure infectious diseases

    PubMed Central

    2014-01-01

    Background Present investigation deals with antimicrobial screening of ten medicinally important plants used by the inhabitants of district Haripur, Khyber Pakhtunkhwa (KPK) for different infectious diseases. Methods Aqueous, n-hexane and ethanolic extracts of each plant were tested for their antimicrobial activity against both Gram positive and Gram negative strains of bacteria, as well as strain of yeast. Agar well diffusion and broth dilution methods were used to determine the antimicrobial activity of different plant extracts. Results The results indicated that all plants exhibited antimicrobial activity against one or more test pathogens. Interestingly, extracts of three plants showed strong and broad spectrum activity as compared to rest of the extracts which demonstrated the moderate activity. On the whole ethanolic extracts exhibited maximum antimicrobial effect than their corresponding aqueous and n-hexane extracts, when compared with standard antibiotics i.e., Streptomycin and Tetracycline. Among various extracts, only ethanloic extract of Azadirachta indica and aqueous and ethanolic extracts of Eucalyptus globulus and Bergenia ciliata and ethanolic extract of Punica granatum were found to have potentially promising activity against test microorganisms. Conclusion Different plant extracts show promising antimicrobial activity justifying their usage in traditional medicines. This study will be continued to identify more plants with potential antimicrobial components. PMID:24708514

  12. Response of Rhodococcus erythropolis strain IBBPo1 to toxic organic solvents.

    PubMed

    Stancu, Mihaela Marilena

    2015-12-01

    Recently, there has been a lot of interest in the utilization of rhodococci in the bioremediation of petroleum contaminated environments. This study investigates the response of Rhodococcus erythropolis IBBPo1 cells to 1% organic solvents (alkanes, aromatics). A combination of microbiology, biochemical, and molecular approaches were used to examine cell adaptation mechanisms likely to be pursued by this strain after 1% organic solvent exposure. R. erythropolis IBBPo1 was found to utilize 1% alkanes (cyclohexane, n-hexane, n-decane) and aromatics (toluene, styrene, ethylbenzene) as the sole carbon source. Modifications in cell viability, cell morphology, membrane permeability, lipid profile, carotenoid pigments profile and 16S rRNA gene were revealed in R. erythropolis IBBPo1 cells grown 1 and 24 h on minimal medium in the presence of 1% alkanes (cyclohexane, n-hexane, n-decane) and aromatics (toluene, styrene, ethylbenzene). Due to its environmental origin and its metabolic potential, R. erythropolis IBBPo1 is an excellent candidate for the bioremediation of soils contaminated with crude oils and other toxic compounds. Moreover, the carotenoid pigments produced by this nonpathogenic Gram-positive bacterium have a variety of other potential applications. PMID:26691458

  13. DPPH scavenging, PRAP activities and essential oil composition of edible Lathyrus ochrus L. (Cyprus Vetch, Luvana) from Cyprus.

    PubMed

    Polato?lu, Kaan; Arsal, Seniha; Demirci, Betül; Ba?er, Kemal Hüsnü Can

    2015-01-01

    The essential oil of the aerial parts of edible Lathyrus ochrus L. was investigated by simultaneous GC, GC/MS analyses under the same conditions. Trace amount of oil (0.01> mL) obtained by hydro distillation of 200 g fresh plants was trapped in 1 mL n-hexane. Twenty components were detected representing 91.55 ± 0.56 % of the oil. The main components were phytol 49.39 ± 0.44 %, hexadecanoic acid 20.64 ± 0.89 % and pentacosane 4.20 ± 0.09 %. Essential oil solution (1% oil: n-hexane) afforded similar DPPH scavenging activity (9.28 ± 1.30 %) when compared with positive controls ?-tocopherol (9.74 ± 0.21 %) and BHT (7.79 ± 0.26 %) at the same concentrations. Antioxidant activity of the oil was determined using a new HPTLC-PRAP assay. The oil afforded two fold higher reducing activity of phosphomolybdenum complex (594.85 ± 5.14 AU) when compared with positive controls ?- tocopherol (271.10 ± 2.86 AU) and BHT (210.53 ± 1.81 AU) at the same concentration. PMID:25757435

  14. The role of aggregate formation in solvent extraction of calcium

    SciTech Connect

    Gaonkar, A.G.; Neuman, R.D.

    1986-09-01

    In solvent extraction processes involving hydrometallurgical separations, spent nuclear fuel reprocessing, and nuclear waste processing operations, metal ions transfer across the boundary between two immiscible liquids. Hence, the properties of the liquid/liquid interface can often influence the extraction process. This suggests that one, therefore, should be able to control the extraction rate by proper manipulation of the nature of the liquid/liquid interface. In an earlier communication (1) from this laboratory, aggregates, possibly reversed micelles, were proposed to form in the system di(2-ethylhexyl)phosphoric acid (HDEHP)/n-hexane/CaCl/sub 2/ solution under certain conditions. The objective of the present study was to determine whether the amount of calcium extracted and the rate of extraction become significant when reversed micelles form. The interfacial tension (..gamma..), equilibrium distribution coefficient (K/sub d/), and mass transfer coefficient (k/sub ao/) were obtained for the system HDEHP/n-hexane/0.01 mol dm/sup -3/ CaCl/sub 2/ solution. 11 refs., 4 figs.

  15. Changes in the phenolic and lipophilic composition, in the enzyme inhibition and antiproliferative activity of Ficus carica L. cultivar Dottato fruits during maturation.

    PubMed

    Marrelli, Mariangela; Menichini, Federica; Statti, Giancarlo A; Bonesi, Marco; Duez, Pierre; Menichini, Francesco; Conforti, Filomena

    2012-03-01

    Fruits of Ficus carica cultivar Dottato from Italy were examined to assess how the stage of ripeness influences their chemical composition, antioxidant activity, pancreatic lipase inhibition and antiproliferative properties on C32 melanoma cells. Fruits of the first harvest (June) showed a major content in furanocoumarins and pyranocoumarins whereas the fruits collected in September showed the highest polyphenolic content (11.9 mg/g of dried material). The total 70% ethanol extracts were portioned between methanol/water and n-hexane, dichloromethane and ethyl acetate, successively. Coumarins and fatty acid esters were the most abundant components of the n-hexane fractions. The dichloromethane fractions showed as major components 2 furanocoumarins (rutarenin and pimpinellin). The total extracts of F. carica cv. Dottato exhibited a significant dose-dependent antiradical and inhibition of lipid peroxidation activity, particularly fruits of the first harvest (June) that showed the highest activity with IC50 of 1.64 mg/mL and 0.004 mg/mL, respectively. Among single fractions, the ethyl acetate fraction from the second harvest (July) showed the highest antiradical activity with an IC50 value of 0.05 mg/mL while the dichloromethane fraction showed the best inhibition of lipid peroxidation with an IC50 value of 0.02 mg/mL. Dichloromethane fractions showed the highest photodynamic cytotoxicity with an IC50<5 ?g/mL. PMID:22222929

  16. The comparison of solid phase microextraction-GC and static headspace-GC for determination of solvent residues in vegetable oils.

    PubMed

    Ligor, Magdalena; Buszewski, Bogus?aw

    2008-02-01

    The objective of these investigations has been the determination of volatile organic compounds including residue solvents present in vegetable oil samples. Some olive oil, rape oil, sunflower oil, soy-bean oil, pumpkin oil, grape oil, rice oil as well as hazel-nut oil samples were analysed. Among residue solvents the following compounds have been mentioned: acetone, n-hexane, benzene, and toluene. Some experiments for the solid phase microextraction (SPME)-GC-flame ionisation detection (FID) were performed to examine extraction conditions such as fiber exposure time, temperature of extraction, and temperature of desorption. Various SPME fibers such as polydimethylsiloxane, Carboxen/polydimethylsiloxane and polydimethylsiloxane/divinylbenzene coatings were used for the isolation of tested compounds from vegetable oil samples. After optimisation of SPME, real vegetable oil samples were examined using SPME-GC/MS. Based on preliminary experiments the qualitative and quantitative analyses for the determination of acetone, n-hexane, benzene and toluene were performed by SPME-GC-FID and static head-space (SHS)-GC-FID methods. The regression coefficients for calibration curves for the examined compounds were R(2) > or = 0.992. This shows that the used method is linear in the examined concentration range (0.005-0.119 mg/kg for SPME-GC-FID and 0.003-0.728 mg/kg for SHS-GC-FID). Chemical properties of analysed vegetable oils have been characterised by chemometric procedure (cluster analysis). PMID:18196521

  17. The effect of rhenium, sulfur and alumina on the conversion of hydrocarbons over platinum single crystals: Surface science and catalytic studies

    SciTech Connect

    Kim, C.

    1992-04-01

    Conversion reactions of hydrocarbons over Pt-Re model catalyst surfaces modified by sulfur and alumina have been studied. A plasma deposition source has been developed to deposit Pt, Re, and Al on metal substrates variable coverage in ultrahigh vacuum without excessive heating. Conversion of n-hexane was performed over the Re-covered Pt and Pt-covered Re surfaces. The presence of the second metal increased hydrogenolysis activity of both Pt-Re surfaces. Addition of sulfur on the model Catalyst surfaces suppressed hydrogenolysis activity and increased the cyclization rate of n-hexane to methylcyclopentane over Pt-Re surfaces. Sulfiding also increased the dehydrogenation rate of cyclohexane to benzene Over Pt-Re surfaces. It has been proposed that the PtRe bimetallic catalysts show unique properties when combined with sulfur, and electronic interactions exist between platinum, rhenium and sulfur. Decomposition of hydrocarbons on the sulfur-covered Pt-Re surfaces supported that argument. For the conversion of 1-butene over the planar Pt/AlO[sub x], the addition of Pt increased the selectivity of hydrogenation over isomerization.

  18. The effect of rhenium, sulfur and alumina on the conversion of hydrocarbons over platinum single crystals: Surface science and catalytic studies

    SciTech Connect

    Kim, C.

    1992-04-01

    Conversion reactions of hydrocarbons over Pt-Re model catalyst surfaces modified by sulfur and alumina have been studied. A plasma deposition source has been developed to deposit Pt, Re, and Al on metal substrates variable coverage in ultrahigh vacuum without excessive heating. Conversion of n-hexane was performed over the Re-covered Pt and Pt-covered Re surfaces. The presence of the second metal increased hydrogenolysis activity of both Pt-Re surfaces. Addition of sulfur on the model Catalyst surfaces suppressed hydrogenolysis activity and increased the cyclization rate of n-hexane to methylcyclopentane over Pt-Re surfaces. Sulfiding also increased the dehydrogenation rate of cyclohexane to benzene Over Pt-Re surfaces. It has been proposed that the PtRe bimetallic catalysts show unique properties when combined with sulfur, and electronic interactions exist between platinum, rhenium and sulfur. Decomposition of hydrocarbons on the sulfur-covered Pt-Re surfaces supported that argument. For the conversion of 1-butene over the planar Pt/AlO{sub x}, the addition of Pt increased the selectivity of hydrogenation over isomerization.

  19. Extent and mechanism of solvation and partitioning of isomers of substituted benzoic acids: a thermodynamic study in the solid state and in solution.

    PubMed

    Perlovich, German L; Volkova, Tatyana V; Manin, Alex N; Bauer-Brandl, Annette

    2008-09-01

    Temperature dependency of saturated vapour pressure and thermochemical characteristics of fusion processes for 2-, 3- and 4-methoxybenzoic acids (anisic acids) were measured and thermodynamic functions of sublimation, fusion, and evaporation calculated. A new approach to split specific and nonspecific energetic terms in the crystal lattice was developed. For methoxybenzoic acid isomers as well as for a number of analogous molecules, a parameter describing molecular packing density by the ratio of free volume of the molecules in the crystal lattice and van der Waals molecular volume is defined. Its relationship to Gibbs energy of sublimation and to the respective melting points was analysed. Temperature dependencies of solubility in buffers with pH 2.0 and 7.4, n-octanol and n-hexane were measured. The thermodynamic functions of solubility, solvation and transfer processes were deduced. Concentration dependence of partition coefficients for the outlined isomers was measured. Specific and nonspecific solvation terms were distinguished using the transfer from the 'inert' n-hexane to the other solvents. Comparison analysis of specific and nonspecific interactions in the solid state and in solution was carried out. A diagram enabling analysis of the mechanism of the partitioning process was applied. It was found that position of substituents essentially affects the mechanism of partitioning in buffer pH 2.0, however, at pH 7.4, the mechanism is independent of the position of the substituent. PMID:18200548

  20. Antibacterial and synergistic effects of Smallanthus sonchifolius leaf extracts against methicillin-resistant Staphylococcus aureus under light intensity.

    PubMed

    Joung, Hee; Kwon, Dong-Yeul; Choi, Jang-Gi; Shin, Dong-Young; Chun, Soon-Sil; Yu, Young-Beob; Shin, Dong-Won

    2010-04-01

    Smallanthus sonchifolius (yacon) is a perennial plant mostly cultivated in South America, primarily for use of the tubers as a food crop and the leaves as fodder for livestock. The antibacterial activities of the methanol extract of yacon leaves (S. sonchifolius) and its n-hexane, ethyl acetate, n-butanol and water fractions were evaluated against 6 strains of methicillin-resistant Staphylococcus aureus (MRSA) and 1 standard methicillin-susceptible S. aureus (MSSA) strain by using the disc diffusion method and minimal inhibitory concentrations (MICs) assay in the presence and absence of light. No activity was detected when the two methods were performed without light; however, under illumination at 4000 lux, the n-hexane fraction of yacon (HFY) had a MIC of 15.6 microg/ml. HFYL, prepared by exposure of HFY to 4000 lux for 18 h, was more effective than HFY in terms of antimicrobial activity against the 6 MRSA strains and 1 standard MSSA strain. HFYL mixed with ampicillin or oxacillin showed a synergistic effect with all fractional inhibitory concentrations values being below 0.5. The present study demonstrates the enhancement and antimicrobial activity of yacon leaves against MRSA in the presence of light. PMID:20119720

  1. Lethal body burdens of polar narcotics: Chlorophenols

    SciTech Connect

    Wezel, A.P. van; Punte, S.S.; Opperhuizen, A.

    1995-09-01

    The goal of the present study was to measure in fathead minnow (Pimephales promelas) the lethal body burden (LBB) of three chlorophenols that are known as polar narcotic chemicals. The LBBs of the chlorophenols were compared to LBBs of nonpolar narcotic chemicals to consider if the two classes of narcotic chemicals differ on a body burden level. The LBB of the most acidic chlorophenol was measured at two different levels of pH exposure to determine the influence of the degree of ionization on the magnitude of the LBB. Both n-octanol/water partition coefficients and n-hexane/water partition coefficients of the chlorophenols were determined at different pH levels to consider the influence of ionization on the partition coefficient and to determine the importance of a polar group in the organic phase on the partitioning behavior. Partitioning to n-octanol and n-hexane was used as input in a model to simulate the equilibrium partitioning between hydrophobic and nonhydrophobic and target and nontarget compartments in the fish.

  2. Control of Meloidogyne javanica by Formulations of Inula viscosa Leaf Extracts

    PubMed Central

    Oka, Yuji; Ben-Daniel, Bat-Hen; Cohen, Yigal

    2006-01-01

    Inula viscosa is a perennial plant that is widely distributed in Mediterranean countries. Formulations of I. viscosa extracts were tested for their effectiveness in control of Meloidogyne javanica in laboratory, growth chamber, microplot, and field experiments. Oily pastes were obtained by extraction of dry leaves with a mixture of acetone and n-hexane or n-hexane alone, followed by evaporation of the solvents. Emulsifiable concentrate formulations of the pastes killed M. javanica juveniles in sand at a concentration of 0.01% (paste, w/w) or greater and reduced the galling index of cucumber seedlings as well as the galling index and numbers of nematode eggs on tomato plants in growth chamber experiments. In microplot experiments, the hexane-extract formulation at 26 g paste/m2 reduced nematode infection on tomato plants in one of two experiments. In a field experiment, a reduction of 40% in root galling index by one of two formulations was observed on lettuce plants. The plant extracts have potential as a natural nematicide, although the formulations need improvement. PMID:19259429

  3. Antioxidant activity and cytotoxicity of the traditional Indonesian medicine Tahongai (Kleinhovia hospita L.) extract.

    PubMed

    Arung, Enos Tangke; Kusuma, Irawan Wijaya; Purwatiningsih, Sri; Roh, Seong-Soo; Yang, Chae Ha; Jeon, Soohyeon; Kim, Yong-Ung; Sukaton, Edi; Susilo, Joko; Astuti, Yuli; Wicaksono, Britanto Dani; Sandra, Ferry; Shimizu, Kuniyoshi; Kondo, Ryuichiro

    2009-12-01

    We investigated the leaves of Kleinhovia hospita, a plant which has been traditionally used in Indonesia as phytotherapy to cure liver disease, to describe antioxidant materials from plant sources. K. hospita leaves were extracted with methanol and further partitioned into n-hexane, diethyl ether, and ethyl acetate. The antioxidant activity of each fraction and the residue was assessed using a 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging method and their cytotoxicity on HepG2 liver cancer cells was determined by a MTT assay. The K. hospita leaf methanol extract showed strong antioxidant activity (96%) compared with vitamin C (98%) by the DPPH method and the measured activity from the subsequent extracts of the methanol extract were 48.9% for n-hexane, 74.0% for diethyl ether, 84.3% for ethyl acetate, and 77.1% for the residue. The MTT assay showed the cytotoxicity of the methanol extract on HepG2 cells at 14%, 76%, and 80% at concentrations of 50 microg/mL, 87.5 microg/mL, and 125 microg/mL, respectively. Leaf extracts of the medicinal plant K. hospita showed potent antioxidant activity and moderate cytotoxicity on HepG2 liver cancer cells. PMID:20633507

  4. Redox properties of ginger extracts: Perspectives of use of Zingiber officinale Rosc. as antidiabetic agent

    PubMed Central

    Cupáková, Máriá; ?ažký, Anton; Mi?ová, Júlia; Kolek, Emil; Košt'álová, Daniela

    2013-01-01

    In traditional medicine, several medicinal plants or their extracts have been used to treat diabetes. Zingiber officinale Roscoe, known commonly as ginger, is consumed worldwide in cookeries as a spice and flavouring agent. It has been used as the spice and medicine for thousands of years. The present study was undertaken to investigate the potential protective effect of Zingiber officinale Rosc. in a model of oxidative damage to pancreatic ? cells. The free radical scavenging activities and composition of the isolated n-hexane and ethanolic extracts were confronted with their protective, antioxidant and cytotoxic effects in INS-1E ? cells. Unlike the n-hexane extract (exerting, paradoxically, stronger antiradical capacity), both low cytotoxicity and remarkable protective effects on ? cell viability, followed by lowering oxidative stress markers were found for the ethanolic extract Zingiber officinale Rosc. The present study is the first pilot study to assess the protective potential of Zingiber officinale Rosc. in a model of cytotoxic conditions imposed by diabetes in ? cells. PMID:24170976

  5. Solutes at the liquid:liquid phase boundary—Solubility and solvent conformational response alter interfacial microsolvation

    NASA Astrophysics Data System (ADS)

    Ghadar, Yasaman; Parmar, Payal; Samuels, Alex C.; Clark, Aurora E.

    2015-03-01

    A detailed understanding of solvent structure and dynamics at liquid:liquid interfaces is a necessary precursor for control and manipulation of these phase boundaries. Experimentally, amphiphilic solutes are often used to alter transport properties across water:organic interfaces; however, a fundamental model for the mechanism of this action has not been determined. This work compares the solvation profiles of ampiphilic solutes that traverse the phase boundary in binary water:n-hexane, and the individual microsolvation processes for interfacial water and hexane molecules therein. Microsolvation is defined as the rare event where one solvent molecule temporarily penetrates the co-solvent phases and is fully solvated therein. The solutes tri-butyl phosphate (TBP), hydrogen di-butyl phosphate, and di-hydrogen mono-butyl phosphate have been examined as they exhibit a systematic increase in aqueous solubility and selectively partition to the interfacial region at the infinite dilution limit. The relationship between adopted configurations of the solute, orientation of the solvent, and the ability of the solute to enhance microsolvation, specifically the ability of n-hexane to penetrate the aqueous phase, is demonstrated within a 20 Å radius of TBP.

  6. Antibacterial, Antifungal, and Insecticidal Potentials of Oxalis corniculata and Its Isolated Compounds

    PubMed Central

    Rehman, Azizur; Rehman, Ali; Ahmad, Ijaz

    2015-01-01

    Oxalis corniculata is a common medicinal plant widely used against numerous infectious diseases. The agrochemical potential of methanolic extract, n-hexane, chloroform, ethyl acetate, and n-butanol fractions were assessed to measure the antibacterial, antifungal, and insecticidal activities of the plant. The crude, chloroform, and n-butanol soluble fractions showed excellent activities against Escherichia coli, Shigella dysenteriae, Salmonella typhi, and Bacillus subtilis but have no activity against Staphylococcus aureus. Similarly the crude, n-hexane, and chloroform fractions were also found to have significant activity against fungal strains including Fusarium solani, Aspergillus flexneri, and Aspergillus flavus and have no activity against Aspergillus niger. Chemical pesticides have shown very good results at the beginning, but with the passage of time the need was realized to use the natural plant sources for the safe control of insects. The current study will provide minor contribution towards it. High mortality rate was recorded for the crude extract and chloroform fraction against Tribolium castaneum. The two isolated compounds 5-hydroxy-6,7,8,4?-tetramethoxyflavone (1) and 5,7,4?-trihydroxy-6,8-dimethoxyflavone (2) were evaluated for antibacterial, antifungal, and insecticidal activities. The results showed that compound 2 was more active than compound 1 against the tested bacterial strains and insects. PMID:25873973

  7. Screening of Bunium bulbocastanum for antibacterial, antifungal, phytotoxic and haemagglutination activities.

    PubMed

    Khan, Ibrar; Ahmad, Haroon; Ali, Nasir; Ahmad, Bashir; Tanoli, Hamid

    2013-07-01

    The current study was aimed at screening the Bunium bulbocastanum for its antibacterial, antifungal, phytotoxic and haemagglutination activities.The crude methanolic extract and n-hexane fraction showed significant (89%) and good activity (61%) against Staphylococcus aureus while the CHCl3fraction was moderately active against S.aureus (53%). Moderate activitywas shown by the EtOAc fraction against B. subtilis (44%). This fraction was inactive against P.aerogenosa and S.aureus. The aqueous fraction showed significant activity against B. subtilis (85%), moderate against S.aureus(34 %) and E. coli (33%)and low activity against P.aerogenosa(29%). Our results for antifungal assay indicated that all the test samples were inactive against all the test fungi. The phytotoxic activity of the plant at 1000 and 100 ?g/ml was: crude methanolic extract (53.33 and 46.66%), n-hexane (46.66 and 26.66%), CHCl3 (20 and 6.66%), EtOAc (46.66 and 26.66%) and aqueous (40 and 33.33%). All the test samples (crude methanolic extract and fractions) of B. bulbocastanum were unable to agglutinate RBCs of the human blood indicating that this species lack phytolectins. PMID:23811459

  8. Effect of pretreating of host oil on coprocessing. Quarterly progress report, October 1, 1993--December 31, 1993

    SciTech Connect

    Wender, I.; Tierney, J.W.

    1994-02-13

    In the last quarterly report we presented results of coprocessing runs made with an Illinois No. 6 coal and an AMOCO VTR (as received) and after the heavy oil had been pretreated a number of different ways. Coal conversions and product yields were presented for each coprocessing experiment. We have now further analyzed results from coprocessing experiments in order to estimate the yields of coal-derived gas, asphaltenes and oil products. Although coal-derived products can not be measured directly from the coprocessing experiments, since coal and petroleum products are commingled, they can be estimated based on repeat reactions with the petroleum solvent alone. This technique assumes that the petroleum solvent reacts to yield the same products whether coal is present or not. When the coal was coprocessed with untreated heavy oil 58% of coal (MAF) was converted to gas and liquid products. We estimated that 7% of coal was converted to oils (n-pentane solubles), 28% to asphaltenes (n-pentane insolubles) and 24% to hydrocarbon gases, mostly methane. When the same coal was coprocessed with AMOCO oil that had been pretreated with 1000 ppM (metal concentration) of Mo naphthenate, 81% of coal was converted; this is an average of two runs. Coal-derived oil yield remained nearly the same at 8% and gas yield remained at 23%. However, the asphaltene yield increased from 28% to 50%. The increase in asphaltenes accounted for the increase in coal conversion. Table 4 shows yields for the case where Illinois No. 6 coal was coprocessed with AMOCO oil that was first pretreated in two steps; step one with 1000 ppM of Mo naphthenate, step two with the catalyst Ni/Mo/Al{sub 2}O{sub 3}. As a result of this reaction, 85% of coal was converted to gas and liquids. Gas yield was 19%, oil yield was 10% and asphaltene yield was 56%. As in the previous run, most of the coal was converted to asphaltenes.

  9. The Impact of Alternative Fuels on Combustion Kinetics

    SciTech Connect

    Pitz, W J; Westbrook, C K

    2009-07-30

    The research targets the development of detailed kinetic models to quantitatively characterize the impact of alternative fuels on the performance of Navy turbines and diesel engines. Such impacts include kinetic properties such as cetane number, flame speed, and emissions as well as physical properties such as the impact of boiling point distributions on fuel vaporization and mixing. The primary focus will be Fischer-Tropsch liquids made from natural gas, coal or biomass. The models will include both the effects of operation with these alternative fuels as well as blends of these fuels with conventional petroleum-based fuels. The team will develop the requisite kinetic rules for specific reaction types and incorporate these into detailed kinetic mechanisms to predict the combustion performance of neat alternative fuels as well as blends of these fuels with conventional fuels. Reduced kinetic models will be then developed to allow solution of the coupled kinetics/transport problems. This is a collaboration between the Colorado School of Mines (CSM) and the Lawrence Livermore National Laboratory (LLNL). The CSM/LLNL team plans to build on the substantial progress made in recent years in developing accurate detailed chemical mechanisms for the oxidation and pyrolysis of conventional fuels. Particular emphasis will be placed upon reactions of the isoalkanes and the daughter radicals, especially tertiary radicals, formed by abstraction from the isoalkanes. The various components of the program are described. We have been developing the kinetic models for two iso-dodecane molecules, using the same kinetic modeling formalisms that were developed for the gasoline and diesel primary reference fuels. These mechanisms, and the thermochemical and transport coefficient submodels for them, are very close to completion at the time of this report, and we expect them to be available for kinetic simulations early in the coming year. They will provide a basis for prediction and selection of desirable F-T molecules for use in jet engine simulations, where we should be able to predict the ignition, combustion and emissions characteristics of proposed fuel components. These mechanisms include the reactions and chemical species needed to describe high temperature phenomena such as shock tube ignition and flammability behavior, and they will also include low temperature kinetics to describe other ignition phenomena such as compression ignition and knocking. During the past years, our hydrocarbon kinetics modeling group at LLNL has focused a great deal on fuels typical of gasoline and diesel fuel. About 10 years ago, we developed kinetic models for the fuel octane primary reference fuels, n-heptane [1] and iso-octane [2], which have 7 and 8 carbon atoms and are therefore representative of typical gasoline fuels. N-heptane represents the low limit of knock resistance with an octane number of 0, while iso-octane is very knock resistant with an octane number of 100. High knock resistance in iso-octane was attributed largely to the large fraction of primary C-H bonds in the molecule, including 15 of the 18 C-H bonds, and the high bond energy of these primary bonds plays a large role in this knock resistance. In contrast, in the much more ignitable n-heptane, 10 of its 16 C-H bonds are much less strongly bound secondary C-H bonds, leading to its very low octane number. All of these factors, as well as a similarly complex kinetic description of the equally important role of the transition state rings that transfer H atoms within the reacting fuel molecules, were quantified and collected into large kinetic reaction mechanisms that are used by many researchers in the fuel chemistry world.

  10. Precipitation polymerization in acetic acid: study of the solvent effect on the morphology of poly(divinylbenzene).

    PubMed

    Yan, Qing; Zhao, Tongyang; Bai, Yaowen; Zhang, Fen; Yang, Wantai

    2009-03-12

    This paper reports on two important results regarding the precipitation polymerization of poly(divinylbenzene) (PDVB) in acetic acid (HAc). (1) Acetic acid is a novel kind of solvent worthy of investigation because it is amphipathic and innoxious. Thus, two kinds of model solvents, methyl ethyl ketone (MEK) and n-heptane, were selected to investigate the solvent effect on the particle morphology of PDVB-55 during precipitation polymerization in acetic acid. Monodisperse PDVB-55 microspheres were obtained with an MEK content of 30 vol % and a DVB loading of 2 vol %. Odd-shaped particles were found to almost disappear when MEK was added. For MEK contents up to 90 vol %, space-filling macrogels consisting of small particles with diameters of around 10 nm were obtained. More homocoagulated particles were produced when n-heptane was added, for which concentrations up to 50 vol % gave rise to cauliflower-like particles. Thus, in the acetic acid system, microspheres, pumpkin-like particles, macrogels, and coagulum could be successfully obtained. (2) The preparation of nonpolar PDVB-55 particles could be more predictable. For the first time-based on the regulation of former studies--the regularity of the dispersive term (delta(d)) on the particle morphology for a PDVB precipitation polymerization system was reported. The three-dimensional Hansen solubility parameters were utilized to perfect the regularity of the Hildebrand solubility parameter. Microspheres or particles were formed in the range of moderate delta values for both parameters, i.e., delta = 20.2-24.3 MPa1/2 or delta = 16 MPa1/2. What was even more important, delta(d) was found to be around 15.4 MPa1/2, and delta(h) should be below 13.5 MPa1/2. Cyclohexane, cyclohexanone, n-butyl acetate, and 1,4-dioxane were used to verify this regularity, and positive results were obtained. Stable, uniform, and well-separated PDVB-55 microspheres and particles were produced as a result of interaction forces between oligomers, polymers, and solvent. PMID:19708162

  11. Opposed Jet Burner Extinction Limits: Simple Mixed Hydrocarbon Scramjet Fuels vs Air

    NASA Technical Reports Server (NTRS)

    Pellett, Gerald L.; Vaden, Sarah N.; Wilson, Lloyd G.

    2007-01-01

    Opposed Jet Burner tools have been used extensively by the authors to measure Flame Strength (FS) of laminar non-premixed H2 air and simple hydrocarbon (HC) air counterflow diffusion flames at 1-atm. FS represents a strain-induced extinction limit based on air jet velocity. This paper follows AIAA-2006-5223, and provides new HC air FSs for global testing of chemical kinetics, and for characterizing idealized flameholding potentials during early scramjet-like combustion. Previous FS data included six HCs, pure and N2-diluted; and three HC-diluted H2 fuels, where FS decayed very nonlinearly as HC was added to H2, due to H-atom scavenging. This study presents FSs on mixtures of (candidate surrogate) HCs, some with very high FS ethylene. Included are four binary gaseous systems at 300 K, and a hot ternary system at approx. 600 K. The binaries are methane + ethylene, ethane + ethylene, methane + ethane, and methane + propylene. The first three also form two ternary systems. The hot ternary includes both 10.8 and 21.3 mole % vaporized n-heptane and full ranges of methane + ethylene. Normalized FS data provide accurate means of (1) validating, globally, chemical kinetics for extinction of non-premixed flames, and (2) estimating (scaling by HC) the loss of incipient flameholding in scramjet combustors. The n-heptane is part of a proposed baseline simulant (10 mole % with 30% methane + 60% ethylene) that mimics the ignition of endothermically cracked JP-7 like kerosene fuel, as suggested by Colket and Spadaccini in 2001 in their shock tube Scramjet Fuels Autoignition Study. Presently, we use FS to gauge idealized flameholding, and define HC surrogates. First, FS was characterized for hot nheptane + methane + ethylene; then a hot 36 mole % methane + 64% ethylene surrogate was defined that mimics FS of the baseline simulant system. A similar hot ethane + ethylene surrogate can also be defined, but it has lower vapor pressure at 300 K, and thus exhibits reduced gaseous capacity. The new FS results refine our earlier idealized reactivity scale that shows wide ranging (50 x) diameter-normalized FSs for various HCs. These range from JP-10 and methane to H2 air, which produces an exceptionally strong flame that agrees within approx. 1% of recent 2-D numerically simulations. Finally, we continue advocating the FS approach as more direct and fundamental, for assessing idealized scramjet flameholding potentials, than measurements of unstrained laminar burning velocity or blowout in a Perfectly Stirred Reactor.

  12. Comparison of ethyl glucuronide and fatty acid ethyl ester concentrations in hair of alcoholics, social drinkers and teetotallers.

    PubMed

    Yegles, M; Labarthe, A; Auwärter, V; Hartwig, S; Vater, H; Wennig, R; Pragst, F

    2004-10-29

    In previous investigations hair analysis for ethyl glucuronide (EtG) and fatty acid ethyl esters (FAEE) proved to be suitable for the detection of excessive alcohol consumption. The aim of this study was to compare EtG and FAEE concentrations in hair of alcoholics, social drinkers and teetotallers. Hair samples from 10 alcoholics in withdrawal treatment, 11 fatalities with documented excessive alcohol consumption, four moderate social drinkers who consumed up to 20 g ethanol per day, and three strict teetotallers were analysed. After external degreasing with n-heptane, extraction with a dimethyl sulfoxide/n-heptane mixture and headspace solid-phase microextraction of the extracts, four fatty acid ethyl esters (FAEEs) (ethyl myristate, ethyl palmitate, ethyl oleate and ethyl stearate) were analysed by gas chromatography-mass spectrometry (GC-MS) with deuterated internal standards. EtG was determined by GC-MS/NCI after ultrasonication of the samples with H2O, cleanup by SPE with aminopropyl columns and PFP derivatisation. The following concentrations were measured for the four groups: teetotallers EtG < 0.002 ng/mg, FAEE 0.05-0.37 ng/mg, moderate social drinkers EtG < 0.002 ng/mg, FAEE 0.26-0.50 ng/mg, alcoholic patients EtG 0.030-0.415 ng/mg, FAEE 0.65-20.50 ng/mg and the fatalities with alcohol history EtG 0.072-3.380 ng/mg, FAEE 1.30-30.60 ng/mg. The results confirm that by using a cut-off value of the sum of FAEE > 1 ng/mg and/or a positive EtG result in hair, excessive alcohol consumption can be identified using hair analysis. However, no significant correlation between the EtG and FAEE concentrations in the positive cases could be shown. Segmental analysis of some of the specimens did not reveal the same distribution for EtG compared to FAEE in hair, and no chronological accordance compared to the self-reported alcohol consumption could be observed for both parameters. These different results of both methods are discussed in terms of differences between EtG and FAEE in mechanism of formation and incorporation into hair and elimination from hair. PMID:15451089

  13. Immobilization and characterization of a new regioselective and enantioselective lipase obtained from a metagenomic library.

    PubMed

    Alnoch, Robson Carlos; Martini, Viviane Paula; Glogauer, Arnaldo; Costa, Allen Carolina dos Santos; Piovan, Leandro; Muller-Santos, Marcelo; de Souza, Emanuel Maltempi; de Oliveira Pedrosa, Fábio; Mitchell, David Alexander; Krieger, Nadia

    2015-01-01

    In previous work, a new lipase and its cognate foldase were identified and isolated from a metagenomic library constructed from soil samples contaminated with fat. This new lipase, called LipG9, is a true lipase that shows specific activities that are comparable to those of well-known industrially-used lipases with high activity against long-chain triglycerides. In the present work, LipG9 was co-expressed and co-immobilized with its foldase, on an inert hydrophobic support (Accurel MP1000). We studied the performance of this immobilized LipG9 (Im-LipG9) in organic media, in order to evaluate its potential for use in biocatalysis. Im-LipG9 showed good stability, maintaining a residual activity of more than 70% at 50 °C after incubation in n-heptane (log P 4.0) for 8 h. It was also stable in polar organic solvents such as ethanol (log P -0.23) and acetone (log P -0.31), maintaining more than 80% of its original activity after 8 h incubation at 30 °C. The synthesis of ethyl esters was tested with fatty acids of different chain lengths in n-heptane at 30 °C. The best conversions (90% in 3 h) were obtained for medium and long chain saturated fatty acids (C8, C14 and C16), with the maximum specific activity, 29 U per gram of immobilized preparation, being obtained with palmitic acid (C16). Im-LipG9 was sn-1,3-specific. In the transesterification of the alcohol (R,S)-1-phenylethanol with vinyl acetate and the hydrolysis of the analogous ester, (R,S)-1-phenylethyl acetate, Im-LipG9 showed excellent enantioselectivity for the R-isomer of both substrates (E> 200), giving an enantiomeric excess (ee) of higher than 95% for the products at 49% conversion. The results obtained in this work provide the basis for the development of applications of LipG9 in biocatalysis. PMID:25706996

  14. Ultrafast studies of electron dynamics at metal-dielectric interfaces

    SciTech Connect

    Ge, Nien-Hui

    1998-10-01

    Femtosecond time- and angle-resolved two-photon photoemission spectroscopy has been used to study fundamental aspects of excited electron dynamics at metal-dielectric interfaces, including layer-by-layer evolution of electronic structure and two-dimensional electron localization. On bare Ag(111), the lifetimes of image states are dominated by their position with respect to the projected bulk band structure. The n = 2 state has a shorter lifetime than the n = 1 state due to degeneracy with the bulk conduction band. As the parallel momentum of the n = 1 image electron increases, the lifetime decreases. With decreasing temperatures, the n = 1 image electrons, with zero or nonzero parallel momentum, all become longer lived. Adsorption of one to three layers of n-heptane results in an approximately exponential increase in lifetime as a function of layer thickness. This results from the formation of a tunneling barrier through which the interfacial electrons must decay, consistent with the repulsive bulk electron affinity of n-alkanes. The lifetimes of the higher quantum states indicate that the presence of the monolayer significantly reduces coupling of the image states to the bulk band structure. These results are compared with predictions of a dielectric continuum model. The study of electron lateral motion shows that optical excitation creates interfacial electrons in quasifree states for motion parallel to the n-heptane/Ag(111) interface. These initially delocalized electrons decay into a localized state within a few hundred femtoseconds. The localized electrons then decay back to the metal by tunneling through the adlayer potential barrier. The localization time depends strongly on the electron's initial parallel momentum and exhibits a non-Arrhenius temperature dependence. The experimental findings are consistent with a 2-D self-trapping process in which electrons become localized by interacting with the topmost plane of the alkane layer. The energy dependence of the self-trapping rate has been modeled with an electron transfer theory. This analysis shows that self-trapping involves inter- and intramolecular vibrational modes of the overlayer and the non-Arrhenius temperature dependence is a result of a strong quantum contribution from the intramolecular modes. These results for a model interface contribute to the fundamental understanding of electron behavior at the interface between metals and molecular solids.

  15. A Detailed Chemical Kinetic Reaction Mechanism for n-Alkane Hydrocarbons from n-Octane to n-Hexadecane

    SciTech Connect

    Westbrook, C K; Pitz, W J; Herbinet, O; Silke, E J; Curran, H J

    2007-09-25

    Detailed chemical kinetic reaction mechanisms have been developed to describe the pyrolysis and oxidation of the n-alkanes, including n-octane (n-C{sub 8}H{sub 18}), n-nonane (n-C{sub 9}H{sub 20}), n-decane (n-C{sub 10}H{sub 22}), n-undecane (n-C{sub 11}H{sub 24}), n-dodecane (n-C{sub 12}H{sub 26}), n-tridecane (n-C{sub 13}H{sub 28}), n-tetradecane (n-C{sub 14}H{sub 30}), n-pentadecane (n-C{sub 15}H{sub 32}), and n-hexadecane (n-C{sub 16}H{sub 34}). These mechanisms include both high temperature and low temperature reaction pathways. The mechanisms are based on previous mechanisms for n-heptane, using the same reaction class mechanism construction developed initially for n-heptane. Individual reaction class rules are as simple as possible in order to focus on the parallelism between all of the n-alkane fuels included in the mechanisms, and there is an intent to develop these mechanisms further in the future to incorporate greater levels of accuracy and predictive capability. Several of these areas for improvement are identified and explained in detail. These mechanisms are validated through comparisons between computed and experimental data from as many different sources as possible. In addition, numerical experiments are carried out to examine features of n-alkane combustion in which the detailed mechanisms can be used to compare processes in all of the n-alkane fuels. The mechanisms for all of these n-alkanes are presented as a single detailed mechanism, which can be edited to produce efficient mechanisms for any of the n-alkanes included, and the entire mechanism, with supporting thermochemical and transport data, together with an explanatory glossary explaining notations and structural details, will be available on our web page when the paper is accepted for publication.

  16. Immobilization and Characterization of a New Regioselective and Enantioselective Lipase Obtained from a Metagenomic Library

    PubMed Central

    Alnoch, Robson Carlos; Martini, Viviane Paula; Glogauer, Arnaldo; Costa, Allen Carolina dos Santos; Piovan, Leandro; Muller-Santos, Marcelo; de Souza, Emanuel Maltempi; de Oliveira Pedrosa, Fábio; Mitchell, David Alexander; Krieger, Nadia

    2015-01-01

    In previous work, a new lipase and its cognate foldase were identified and isolated from a metagenomic library constructed from soil samples contaminated with fat. This new lipase, called LipG9, is a true lipase that shows specific activities that are comparable to those of well-known industrially-used lipases with high activity against long-chain triglycerides. In the present work, LipG9 was co-expressed and co-immobilized with its foldase, on an inert hydrophobic support (Accurel MP1000). We studied the performance of this immobilized LipG9 (Im-LipG9) in organic media, in order to evaluate its potential for use in biocatalysis. Im-LipG9 showed good stability, maintaining a residual activity of more than 70% at 50°C after incubation in n-heptane (log P 4.0) for 8 h. It was also stable in polar organic solvents such as ethanol (log P -0.23) and acetone (log P -0.31), maintaining more than 80% of its original activity after 8 h incubation at 30°C. The synthesis of ethyl esters was tested with fatty acids of different chain lengths in n-heptane at 30 °C. The best conversions (90% in 3 h) were obtained for medium and long chain saturated fatty acids (C8, C14 and C16), with the maximum specific activity, 29 U per gram of immobilized preparation, being obtained with palmitic acid (C16). Im-LipG9 was sn-1,3-specific. In the transesterification of the alcohol (R,S)-1-phenylethanol with vinyl acetate and the hydrolysis of the analogous ester, (R,S)-1-phenylethyl acetate, Im-LipG9 showed excellent enantioselectivity for the R-isomer of both substrates (E> 200), giving an enantiomeric excess (ee) of higher than 95% for the products at 49% conversion. The results obtained in this work provide the basis for the development of applications of LipG9 in biocatalysis. PMID:25706996

  17. Micellization and adsorption behavior of a near-monodisperse polystyrene-based diblock copolymer in nonpolar media.

    PubMed

    Growney, David J; Mykhaylyk, Oleksandr O; Armes, Steven P

    2014-06-01

    The micellar self-assembly behavior of a near-monodisperse polystyrene-hydrogenated polyisoprene (PS-PEP) diblock copolymer is examined in non-polar media (either n-heptane or n-dodecane). Direct dissolution of this diblock copolymer leads to the formation of relatively large polydisperse colloidal aggregates that are kinetically frozen artifacts of the solid-state copolymer morphology. Dynamic light scattering (DLS) and transmission electron microscopy studies indicate that heating such copolymer dispersions up to 90-110 °C leads to a structural rearrangement, with the generation of relatively small, well-defined spherical micelles that persist on cooling to 20 °C. Variable temperature (1)H NMR studies using deuterated n-alkanes confirm that partial solvation (plasticization) of the polystyrene micelle cores occurs on heating. This increased mobility of the core-forming polystyrene chains is consistent with the evolution from a kinetically-trapped to a thermodynamically-favored copolymer morphology via exchange of individual copolymer chains, which are observed by DLS. These micellar self-assembly observations are also consistent with small-angle X-ray scattering (SAXS) studies, which indicate the formation of star-like micelles in n-heptane, with a mean polystyrene core diameter of about 20 nm and an overall diameter (core plus corona) of about 80 nm. Micelle dissociation occurs on addition of chloroform, which is a good solvent for both blocks. Finally, physical adsorption of this PS-PEP diblock copolymer onto a model colloidal substrate (carbon black) has been confirmed using X-ray photoelectron spectroscopy. A Langmuir-type adsorption isotherm has been constructed using a supernatant depletion assay based on UV spectroscopy analysis of the aromatic chromophore in the polystyrene block. Comparable results were obtained using thermogravimetric analysis to directly determine the amount of adsorbed copolymer. Based on the maximum adsorbed amounts observed at 20 °C, these studies strongly suggest that individual PS-PEP copolymer chains adsorb onto carbon black from chloroform, whereas micellar adsorption occurs from n-alkanes. PMID:24818878

  18. EPR and EOM studies in well samples from some Venezuelan oil fields: possible mechanisms of magnetic authigenesis

    NASA Astrophysics Data System (ADS)

    Aldana, M.; Díaz, M.; Costanzo-Alvarez, V.; Jiménez, S. M.; Sequera, P.

    2003-04-01

    In the last few years we have conducted Electron Paramagnetic Resonance (EPR) and Magnetic Susceptibility (MS) studies in drilling fines, from near-surface levels, from producer and non-producer wells. These studies were aimed at examining a possible causal relationship between magnetic contrasts and underlying hydrocarbons. In this work we have extended these studies to some new wells, trying to identify the possible origin (microbial and/or thermochemical) of the observed anomalies. Together with EPR and MS studies, quantification of extractable organic matter (EOM) has been also performed. The samples were pulverized and split into two aliquots. One aliquot was treated with chloroform in order to separate de EOM and obtain the sample without EOM and the EOM itself. The other aliquot was not solvent extracted. The EOM was quantified and EPR measurements were performed on both aliquots in order to determine the organic matter free radical concentration (OMFRC). The treatments performed allow identifying whether the OMFRC belongs to the EOM or to the total organic matter (TOM). Asphaltenes tend to be the major components in highly biodegraded crude oils. Then the presence of OMFRC belonging to the TOM or to the EOM could indicate a possible microbial or thermochemical origin, respectively, of the detected MS anomalies. We have found OMFRC and EOM anomalies only at the producer wells, in the same zone where MS anomalies, associated with the presence of spherical aggregates of magnetic minerals, were observed. For some of these wells our results indicate the solely presence of free radicals of kerogen at OMFRC anomalous level. In fact, the EOM of these wells has no EPR signal and precipitation of asphaltene in n-heptane was not observed. In other instances, free radicals of kerogen and asphaltenes and precipitation of asphaltene from the EOM in n-heptane was observed. In the former case we suggest the existence of a reducing zone where thermochemical conditions are appropriated for the precipitation of authigenic magnetic minerals (possibly responsible for the MS anomalies). In the second case, a combination of two processes, i.e. thermochemical reactions and oil biodegradation, could have taken place leading to the formation of diagenetic minerals in these wells.

  19. Dual-Stage Consumable-Free Thermal Modulator for the Hyphenation of Thermal Analysis, Gas Chromatography, and Mass Spectrometry.

    PubMed

    Wohlfahrt, Sebastian; Fischer, Michael; Varga, Janos; Saraji-Bozorgzad, Mohammad-Reza; Matuschek, Georg; Denner, Thomas; Zimmermann, Ralf

    2016-01-01

    The design of the so-called "Peltier modulator" is presented. It is a new dual-stage consumable-free thermal modulator for thermal analysis-gas chromatography-mass spectrometry (TA-GC-MS). It requires only electrical power for operation as it facilitates thermo-electric coolers instead of cryogenics for trapping and resistive on-column heating for reinjection. Trapping and desorption temperatures as well as modulation cycles are freely adjustable. The stationary phase for the trapping region can be selected to suit the specific application, since common fused silica capillary is used. The Peltier modulator's performance is demonstrated with a broad range of different standard substances and with heavy crude oil as a complex real life sample. Successful modulation from n-pentane to pyrene (boiling points = 36/394 °C) is presented. The produced peaks show the narrowest bandwidths ever reported for a consumable-free thermal modulator, i.e., 12.8 ± 1.2 ms for n-pentadecane. The Peltier modulator is rugged, cost-effective, requires low maintenance, and decreases security issues significantly, compared to commercial available solutions using liquid N2/CO2. PMID:26606252

  20. Characterization of Physically and Chemically Separated Athabasca Asphaltenes Using Small-Angle X-ray Scattering

    SciTech Connect

    Amundaraín Hurtado, Jesús Leonardo; Chodakowski, Martin; Long, Bingwen; Shaw, John M.

    2012-02-07

    Athabasca asphaltenes were characterized using small-angle X-ray scattering (SAXS). Two methods were used to separate asphaltenes from the Athabasca bitumen: namely, chemical separation by precipitation with n-pentane and physical separation by nanofiltration using a zirconia membrane with a 20 nm average pore size. The permeate and chemically separated samples were diluted in 1-methylnaphtalene and n-dodecane prior to SAXS measurements. The temperature and asphaltene concentration ranges were 50-310 C and 1-10.4 wt %, respectively. Model-independent analysis of SAXS data provided the radius of gyration and the scattering coefficients. Model-dependent fits provided size distributions for asphaltenes assuming that they are dense and spherical. Model-independent analysis for physically and chemically separated asphaltenes showed significant differences in nominal size and structure, and the temperature dependence of structural properties. The results challenge the merits of using chemically separated asphaltene properties as a basis for asphaltene property prediction in hydrocarbon resources. While the residuals for model-dependent fits are small, the results are inconsistent with the structural parameters obtained from model-independent analysis.

  1. Generation of gas and liquid hydrocarbon mixtures from a single pressurized cylinder for inhalation exposures

    SciTech Connect

    Leach, C.L.; Hatoum, N.S.; Ledbetter, A.D.

    1985-02-01

    The generation of controlled atmospheres composed of mixtures of gases and liquids from a single pressurized gas cylinder is very difficult, yet logistically desirable. An equal mixture of the hydrocarbons n-butane, isobutane, n-pentane and isopentane was pressurized to 250 p.s.i.g. with nitrogen in a gas cylinder. The four-component mixture was taken from the cylinder as a liquid to a heated microvalve where all components underwent a simultaneous liquid to gas phase change. The resultant vapor was drawn through a heated delivery line maintained at a negative partial pressure to the mixing turret of a one cubic meter inhalation chamber. In this manner, the concentrations of total hydrocarbons and the relative make-up of the components were kept constant. The functional operation of the system was confirmed during the conduct of a three-week inhalation toxicity study at target concentrations of 0.11, 1.11, and 11.11 mg/L. The actual analytical concentrations were within 9% of the target values with standard deviations of less than 8% of the means.

  2. Small-Area, Resistive Volatile Organic Compound (VOC) Sensors Using Metal-Polymer Hybrid Film Based on Oxidative Chemical Vapor Deposition (oCVD).

    PubMed

    Wang, Xiaoxue; Hou, Sichao; Goktas, Hilal; Kovacik, Peter; Yaul, Frank; Paidimarri, Arun; Ickes, Nathan; Chandrakasan, Anantha; Gleason, Karen

    2015-08-01

    We report a novel room temperature methanol sensor comprised of gold nanoparticles covalently attached to the surface of conducting copolymer films. The copolymer films are synthesized by oxidative chemical vapor deposition (oCVD), allowing substrate-independent deposition, good polymer conductivity and stability. Two different oCVD copolymers are examined: poly(3,4-ethylenedioxythiophene-co-thiophene-3-aceticacid)[poly(EDOT-co-TAA)] and poly(3,4-ehylenedioxythiophene-co-thiophene-3-ethanol)[poly(EDOT-co-3-TE)]. Covalent attachment of gold nanoparticles to the functional groups of the oCVD films results in a hybrid system with efficient sensing response to methanol. The response of the poly(EDOT-co-TAA)/Au devices is found to be superior to that of the other copolymer, confirming the importance of the linker molecules (4-aminothiophenol) in the sensing behavior. Selectivity of the sensor to methanol over n-pentane, acetone, and toluene is demonstrated. Direct fabrication on a printed circuit board (PCB) is achieved, resulting in an improved electrical contact of the organic resistor to the metal circuitry and thus enhanced sensing properties. The simplicity and low fabrication cost of the resistive element, mild working temperature, together with its compatibility with PCB substrates pave the way for its straightforward integration into electronic devices, such as wireless sensor networks. PMID:26176840

  3. Central Appalachian basin natural gas database: distribution, composition, and origin of natural gases

    USGS Publications Warehouse

    Román Colón, Yomayra A.; Ruppert, Leslie F.

    2015-01-01

    The U.S. Geological Survey (USGS) has compiled a database consisting of three worksheets of central Appalachian basin natural gas analyses and isotopic compositions from published and unpublished sources of 1,282 gas samples from Kentucky, Maryland, New York, Ohio, Pennsylvania, Tennessee, Virginia, and West Virginia. The database includes field and reservoir names, well and State identification number, selected geologic reservoir properties, and the composition of natural gases (methane; ethane; propane; butane, iso-butane [i-butane]; normal butane [n-butane]; iso-pentane [i-pentane]; normal pentane [n-pentane]; cyclohexane, and hexanes). In the first worksheet, location and American Petroleum Institute (API) numbers from public or published sources are provided for 1,231 of the 1,282 gas samples. A second worksheet of 186 gas samples was compiled from published sources and augmented with public location information and contains carbon, hydrogen, and nitrogen isotopic measurements of natural gas. The third worksheet is a key for all abbreviations in the database. The database can be used to better constrain the stratigraphic distribution, composition, and origin of natural gas in the central Appalachian basin.

  4. Determination and levels of the biocide ortho-phenylphenol in canned beers from different countries.

    PubMed

    Coelhan, Mehmet; Bromig, Karl-Heinz; Glas, Karl; Roberts, A Lynn

    2006-08-01

    A method was developed for the determination of the biocide ortho-phenylphenol (biphenyl-2-ol; OPP) in beer, using deuterated OPP as an internal standard. A new liquid-liquid extraction procedure, employing acetonitrile, diethyl ether, and n-pentane, afforded rapid phase separation. The evaporated extract was derivatized with pentafluorobenzyl bromide in a water-acetonitrile mixture that was buffered with potassium carbonate, followed by extraction of the derivative into cyclohexane and analysis by gas chromatography-mass spectrometry in electron ionization mode. The method enables the detection of OPP in 50 mL of beer at concentrations as low as 0.1 microg/L and provides a linear range of quantification of 0.5-40 microg/L. Samples from 61 beers canned over the past 12 years and sold in 27 countries were analyzed for OPP. In 40 of them, the target compound was present at concentrations of 1.2-40 microg/L. Our investigations indicate that the ends of the cans, which contain sealing material presumably treated with OPP, are responsible for this contamination. PMID:16881670

  5. Effect of cyclic chain architecture on properties of dilute solutions of polyethylene from molecular dynamics simulations

    NASA Astrophysics Data System (ADS)

    Jang, Seung Soon; ?a?in, Tahir; Goddard, William A.

    2003-07-01

    We have used molecular dynamics methods to investigate the effects of cyclic chain architecture on the properties of dilute solutions. In order to include solvent effects in estimating these properties, we use a van der Waals scaling factor determined for each solvent by matching to the theta condition. We predict that the theta temperature (?) of cyclic PE (c-PE) is ˜10% lower than for the linear case (l-PE). This can be compared to the experimental results for polystyrene (PS), where ? for cyclic PS is 2% lower. For conditions corresponding to n-pentane solvent, we predict that cyclic/linear is 0.59 for all temperatures above 350 K. The deviation from the ratio of 0.50-0.53 expected from analytic theory is due to the competition between chain stiffness and excluded volume effects. To calculate the intrinsic viscosity of c-PE and l-PE we extended the Bloomfield-Zimm type theory to include chain stiffness corrections. We find that for the theta temperature, the ratio of viscosities for c-PE and l-PE is 0.71, which is 7% higher than the value of 0.66 from the freely jointed chain model. This difference is caused by the larger value of cyclic/linear from the simulations.

  6. A selected ion flow tube study of the reactions of NO + and O + 2 ions with some organic molecules: The potential for trace gas analysis of air

    NASA Astrophysics Data System (ADS)

    Špan?l, Patrik; Smith, David

    1996-02-01

    A study has been carried out using our selected ion flow tube apparatus of the reactions of NO+ and O+2 ions in their vibronic ground states with ten organic species: the hydrocarbons, benzene, toluene, isoprene, cyclopropane, and n-pentane; the oxygen-containing organics, methanol, ethanol, acetaldehyde, acetone, and diethyl ether. The major objectives of this work are, on the one hand, to fully understand the processes involved in these reactions and, on the other hand, to explore the potential of NO+ and O+2 as chemical ionization agents for the analysis of trace gases in air and on human breath. Amongst the NO+ reactions, charge transfer, hydride-ion transfer, and termolecular association occur, and the measured rate coefficients, k, for the reactions vary from immeasurably small to the maximum value, collisional rate coefficient, kc. The O+2 reactions are all fast, in each case the k being equal to or an appreciable fraction of kc, and charge transfer producing the parent organic ion or dissociative charge transfer resulting in two or three fragments of the parent ion are the reaction processes that occur. We conclude from these studies, and from previous studies, that NO+ ions and O+2 ions can be used to great effect as chemical ionization agents for trace gas analysis, especially in combination with H3O+ ions which we now routinely use for this purpose.

  7. Experimental study of an upward sub-cooled forced convection in a rectangular channel

    NASA Astrophysics Data System (ADS)

    Kouidri, A.; Madani, B.; Roubi, B.; Hamadouche, A.

    2015-08-01

    The upward sub-cooled forced convection in a rectangular channel is investigated experimentally. The aim of the present work is the studying of the local heat transfer phenomena. Concerning the experimentation: the n-pentane is used as a working fluid, the independent variables are: the velocity in the range from 0.04 to 0.086 m/s and heat flux density with values between 1.8 and 7.36 W/cm2. The results show that the local Nusselt number distribution is not uniform along the channel; however, uniformity is observed in the mean Nusselt number for Reynolds under 1600. On the other hand, a new correlation to predict the local fluid temperature is established as a function of local wall temperature. The wall's heat is dissipated under the common effect of the sub-cooled regime; therefore, the local heat transfer coefficient is increased. The study of the thermal equilibrium showed that for Reynolds less than 1500; almost all of the heat flux generated by the heater cartridges is absorbed by the fluid.

  8. Modification of the surface pathways in alkane oxidation by selective doping of Bronsted acid sites of vanadyl pyrophosphate

    SciTech Connect

    Centi, G.; Golinelli, G.; Busca, G. )

    1990-08-23

    The modification of Bronsted POH groups of (VO){sub 2}P{sub 2}O{sub 7} by selective doping with K in an anhydrous medium causes a considerable modification of the surface oxidation pathways in C{sub 4}- and C{sub 5}-alkane oxidative transformation, with (i) a considerable decrease in the selective formation of maleic anhydride from n-butane and of maleic and phthalic anhydrides from n-pentane, (ii) an increase in the relative formation of C-containing surface residues. It is suggested that these effects are due to an inhibition of the catalyzed transformation of furan-like intermediates to corresponding lactones and then to anhydrides in the presence of gaseous O{sub 2} and to a change in the relative rates of O-insertion and H-abstraction on these surface intermediates. The role of the dynamics of competitive surface transformations of adsorbed intermediates on the overall behavior of vanadyl pyrophosphate in C{sub 4}- and C{sub 5}-alkane selective oxidation is also discussed.

  9. High-temperature measurements of methane and acetylene using quantum cascade laser absorption near 8 ?m

    NASA Astrophysics Data System (ADS)

    Sajid, M. B.; Javed, T.; Farooq, A.

    2015-04-01

    The mid-infrared wavelength region near 8 ?m contains absorption bands of several molecules such as water vapor, hydrogen peroxide, nitrous oxide, methane and acetylene. A new laser absorption sensor based on the ?4 band of methane and the ?4+?5 band of acetylene is reported for interference-free, time-resolved measurements under combustion-relevant conditions. A detailed line-selection procedure was used to identify optimum transitions. Methane and acetylene were measured at the line centers of Q12 (1303.5 cm-1) and P23 (1275.5 cm-1) transitions, respectively. High-temperature absorption cross sections of methane and acetylene were measured at peaks (on-line) and valleys (off-line) of the selected absorption transitions. The differential absorption strategy was employed to eliminate interference absorption from large hydrocarbons. Experiments were performed behind reflected shock waves over a temperature range of 1200-2200 K, between pressures of 1-4 atm. The diagnostics were then applied to measure the respective species time-history profiles during the shock-heated pyrolysis of n-pentane.

  10. Characterization of Atmospheric Volatile Organic Compounds in the North Dakota Bakken Formation

    NASA Astrophysics Data System (ADS)

    Sive, B. C.; Zhou, Y.; Day, D.; Desyaterik, Y.; Evanoski-Cole, A. R.; Gebhart, K.; Hecobian, A.; Li, Y.; Malm, W. C.; Prenni, A. J.; Schichtel, B. A.; Schurman, M. I.; Sullivan, A.; Vimont, J.; Collett, J. L., Jr.

    2014-12-01

    A field campaign was conducted from 23 November 2013 through 28 March 2014 in the Bakken formation of North Dakota to investigate the impacts of rapidly increasing oil and gas production operations on air quality throughout the region. Whole air samples were collected at three different sites during the study period for volatile organic compound (VOC) measurements. The main sampling location was the north unit of Theodore Roosevelt National Park (THRO), where one daytime and one nighttime sample were collected each day throughout the campaign period. Daytime samples were also collected every second day at the Fort Union Trading Post National Historic Site (FOUS) and once a week at the Medicine Lake National Wildlife Refuge, MT. A signature of elevated nonmethane hydrocarbon (NMHC) mixing ratios was observed throughout the campaign at all three sites; THRO and FOUS had the highest levels as they are located in high well density areas. Moreover, the C2-C5 alkane mixing ratios were approximately an order of magnitude greater than regional background levels. Light alkane mixing ratios at THRO, the most impacted site, were similar to those at urban sites influenced by petrochemical industry emissions, with ethane and propane reaching maximums of 95 ppbv and 164 ppbv, respectively. The i-pentane to n-pentane ratio for all sites was ~0.75, clearly demonstrating the widespread impact from oil and gas production emissions throughout the region. Alkanes dominated the hydroxyl radical reactivity, and their overall influence on regional air quality will be explored.

  11. Gas/oil capillary pressure at chalk at elevated pressures

    SciTech Connect

    Christoffersen, K.R.; Whitson, C.H.

    1995-09-01

    Accurate capillary pressure curves are essential for studying the recovery of oil by gas injection in naturally fractured chalk reservoirs. A simple and fast method to determine high-pressure drainage capillary pressure curves has been developed. The effect of gas/oil interfacial tension (IFT) on the capillary pressure of chalk cores has been determined for a methane/n-pentane system. Measurements on a 5-md outcrop chalk core were made at pressures of 70, 105, and 130 bar, with corresponding IFT`s of 6.3, 3.2, and 1.5 mN/m. The results were both accurate and reproducible. The measured capillary pressure curves were not a linear function of IFT when compared with low-pressure centrifuge data. Measured capillary pressures were considerably lower than IFT-scaled centrifuge data. It appears that the deviation starts at an IFT of about 5 mN/m. According to the results of this study, the recovery of oil by gravity drainage in naturally fractured chalk reservoirs may be significantly underestimated if standard laboratory capillary pressure curves are scaled by IFT only. However, general conclusions cannot be made on the basis on only this series of experiments on one chalk core.

  12. Expression of an alkane monooxygenase (alkB) gene and methyl tert-butyl ether co-metabolic oxidation in Pseudomonas citronellolis.

    PubMed

    Bravo, Ana Luisa; Sigala, Juan Carlos; Le Borgne, Sylvie; Morales, Marcia

    2015-04-01

    Pseudomonas citronellolis UAM-Ps1 co-metabolically transforms methyl tert-butyl ether (MTBE) to tert-butyl alcohol with n-pentane (2.6 mM), n-octane (1.5 mM) or dicyclopropylketone (DCPK) (4.4 mM), a gratuitous inducer of alkane hydroxylase (AlkB) activity. The reverse transcription quantitative real-time PCR was used to quantify the alkane monooxygenase (alkB) gene expression. The alkB gene was expressed in the presence of n-alkanes and DCPK and MTBE oxidation occurred only in cultures when alkB was transcribed. A correlation between the number of alkB transcripts and MTBE consumption was found (???? consumption in ?mol = 1.44e(-13) x DNA copies, R(2) = 0.99) when MTBE (0.84 mM) was added. Furthermore, alkB was cloned and expressed into Escherichia coli and the recombinant AlkB had a molecular weight of 42 kDa. This is the first report where the expression of alkB is related to the co-metabolic oxidation of MTBE. PMID:25432418

  13. Marangoni-Benard Convection in a Evaporating Liquid Thin Layer

    NASA Technical Reports Server (NTRS)

    Chai, An-Ti; Zhang, Nengli

    1996-01-01

    Marangoni-Benard convection in evaporating liquid thin layers has been investigated through flow visualization and temperature profile measurement. Twelve liquids, namely ethyl alcohol, methanol, chloroform, acetone, cyclohexane, benzine, methylene chloride, carbon tetrachloride, ethyl acetate, n-pentane, silicone oil (0.65 cSt.), and freon-113, were tested and convection patterns in thin layers of these samples were observed. Comparison among these tested samples shows that some liquids are sensitive to surface contamination from aluminum powder but some are not. The latter is excellent to be used for the investigation of surface-tension driven convection through visualization using the tracer. Two sample liquids, alcohol and freon-113 were particularly selected for systematic study. It was found that the wavelength of Benard cells would not change with thickness of the layer when it evaporates at room temperature. Special attention was focused on cases in which a liquid layer was cooled from below, and some interesting results were obtained. Convection patterns were recorded during the evaporation process and the patterns at certain time frame were compared. Benard cells were observed in thin layers with a nonlinear temperature profile and even with a zero or positive temperature gradient. Wavelength of the cells was found to increase as the evaporation progressed.

  14. Atmospheric Mercury in the Barnett Shale Area, Texas: Implications for Emissions from Oil and Gas Processing.

    PubMed

    Lan, Xin; Talbot, Robert; Laine, Patrick; Torres, Azucena; Lefer, Barry; Flynn, James

    2015-09-01

    Atmospheric mercury emissions in the Barnett Shale area were studied by employing both stationary measurements and mobile laboratory surveys. Stationary measurements near the Engle Mountain Lake showed that the median mixing ratio of total gaseous mercury (THg) was 138 ppqv (140 ± 29 ppqv for mean ± S.D.) during the June 2011 study period. A distinct diurnal variation pattern was observed in which the highest THg levels appeared near midnight, followed by a monotonic decrease until midafternoon. The influence of oil and gas (ONG) emissions was substantial in this area, as inferred from the i-pentane/n-pentane ratio (1.17). However, few THg plumes were captured by our mobile laboratory during a ?3700 km survey with detailed downwind measurements from 50 ONG facilities. One compressor station and one natural gas condensate processing facility were found to have significant THg emissions, with maximum THg levels of 963 and 392 ppqv, respectively, and the emissions rates were estimated to be 7.9 kg/yr and 0.3 kg/yr, respectively. Our results suggest that the majority of ONG facilities in this area are not significant sources of THg; however, it is highly likely that a small number of these facilities contribute a relatively large amount of emissions in the ONG sector. PMID:26218013

  15. Migration of carbon nanotubes from liquid phase to vapor phase in the refrigerant-based nanofluid pool boiling

    PubMed Central

    2011-01-01

    The migration characteristics of carbon nanotubes from liquid phase to vapor phase in the refrigerant-based nanofluid pool boiling were investigated experimentally. Four types of carbon nanotubes with the outside diameters from 15 to 80 nm and the lengths from 1.5 to 10 ?m were used in the experiments. The refrigerants include R113, R141b and n-pentane. The oil concentration is from 0 to 10 wt.%, the heat flux is from 10 to 100 kW·m-2, and the initial liquid-level height is from 1.3 to 3.4 cm. The experimental results indicate that the migration ratio of carbon nanotube increases with the increase of the outside diameter or the length of carbon nanotube. For the fixed type of carbon nanotube, the migration ratio decreases with the increase of the oil concentration or the heat flux, and increases with the increase of the initial liquid-level height. The migration ratio of carbon nanotube increases with the decrease of dynamic viscosity of refrigerant or the increase of liquid phase density of refrigerant. A model for predicting the migration ratio of carbon nanotubes in the refrigerant-based nanofluid pool boiling is proposed, and the predictions agree with 92% of the experimental data within a deviation of ±20%. PMID:21711730

  16. Bayesian parametrization of coarse-grain dissipative dynamics models

    NASA Astrophysics Data System (ADS)

    Dequidt, Alain; Solano Canchaya, Jose G.

    2015-08-01

    We introduce a new bottom-up method for the optimization of dissipative coarse-grain models. The method is based on Bayesian optimization of the likelihood to reproduce a coarse-grained reference trajectory obtained from analysis of a higher resolution molecular dynamics trajectory. This new method is related to force matching techniques, but using the total force on each grain averaged on a coarse time step instead of instantaneous forces. It has the advantage of not being limited to pairwise short-range interactions in the coarse-grain model and also yields an estimation of the friction parameter controlling the dynamics. The theory supporting the method is exposed in a practical perspective, with an analytical solution for the optimal set of parameters. The method was first validated by using it on a system with a known optimum. The new method was then tested on a simple system: n-pentane. The local molecular structure of the optimized model is in excellent agreement with the reference system. An extension of the method allows to get also an excellent agreement for the equilibrium density. As for the dynamic properties, they are also very satisfactory, but more sensitive to the choice of the coarse-grain representation. The quality of the final force field depends on the definition of the coarse grain degrees of freedom and interactions. We consider this method as a serious alternative to other methods like iterative Boltzmann inversion, force matching, and Green-Kubo formulae.

  17. Free energy from molecular dynamics with multiple constraints

    NASA Astrophysics Data System (ADS)

    den Otter, W. K.; Briels, W. J.

    In molecular dynamics simulations of reacting systems, the key step to determining the equilibrium constant and the reaction rate is the calculation of the free energy as a function of the reaction coordinate. Intuitively the derivative of the free energy is equal to the average force needed to constrain the reaction coordinate to a constant value, but the metric tensor effect of the constraint on the sampled phase space distribution complicates this relation. The appropriately corrected expression for the potential of mean constraint force method (PMCF) for systems in which only the reaction coordinate is constrained was published recently. Here we will consider the general case of a system with multiple constraints. This situation arises when both the reaction coordinate and the 'hard' coordinates are constrained, and also in systems with several reaction coordinates. The obvious advantage of this method over the established thermodynamic integration and free energy perturbation methods is that it avoids the cumbersome introduction of a full set of generalized coordinates complementing the constrained coordinates. Simulations of n -butane and n -pentane in vacuum illustrate the method.

  18. Fundamental Study of the Oxidation Characteristics and Pollutant Emissions of Model Biodiesel Fuels

    SciTech Connect

    Feng, Q.; Wang, Y. L.; Egolfopoulos, Fokion N.; Tsotsis, T. T.

    2010-07-18

    In this study, the oxidation characteristics of biodiesel fuels are investigated with the goal of contributing toward the fundamental understanding of their combustion characteristics and evaluating the effect of using these alternative fuels on engine performance as well as on the environment. The focus of the study is on pure fatty acid methyl-esters (FAME,) that can serve as surrogate compounds for real biodiesels. The experiments are conducted in the stagnation-flow configuration, which allows for the systematic evaluation of fundamental combustion and emission characteristics. In this paper, the focus is primarily on the pollutant emission characteristics of two C{sub 4} FAMEs, namely, methyl-butanoate and methyl-crotonate, whose behavior is compared with that of n-butane and n-pentane. To provide insight into the mechanisms of pollutant formation for these fuels, the experimental data are compared with computed results using a model with consistent C1-C4 oxidation and NOx formation kinetics.

  19. Characterization of Athabasca Asphaltenes Separated Physically and Chemically Using Small-Angle X-Ray Scattering

    NASA Astrophysics Data System (ADS)

    Amundarain Hurtado, Jesus Leonardo

    Athabasca asphaltenes were characterized using small-angle X-ray scattering (SAXS) with synchrotron radiation. Two methods were used to separate asphaltenes from Athabasca bitumen. Conventional chemical separation by precipitation with n-pentane, and physical separation realized by passing bitumen through a zirconia membrane with a 20 nm average pore size. The Athabasca permeates and chemically separated samples were dispersed in 1-methylnaphtalene and n-dodecane, with temperature and asphaltene concentration ranges of 50-310 °C and 1-8 wt. %, respectively. Two approaches were also taken in the analysis of the SAXS emissions. A model-independent approach provided radii of gyration and scattering coefficients. A model-dependent fit provided size distributions for asphaltenes aggregates assuming that they are dense and spherical. Physically and chemically separated asphaltenes showed significant differences in nominal size and structure, and their structural properties exhibited different temperature dependencies. The results challenge the merits of using chemically separated asphaltene properties as a basis for asphaltene property prediction in crude oil/bitumen.

  20. Combustion of liquid-fuel droplets in supercritical conditions

    NASA Technical Reports Server (NTRS)

    Shuen, J. S.; Yang, Vigor; Hsaio, C. C.

    1992-01-01

    A comprehensive analysis of liquid-fuel droplet combustion in both subcritical and supercritical environments has been conducted. The formulation is based on the complete conservation equations for both gas and liquid phases, and accommodates variable thermophysical properties, finite-rate chemical kinetics, and a full treatment of liquid-vapor phase equilibrium at the drop surface. The governing equations and associated interfacial boundary conditions are solved numerically using a fully coupled, implicit scheme with the dual time-stepping integration technique. The model is capable of treating the entire droplet history, including the transition from the subcritical to supercritical state. As a specific example, the combustion of n-pentane fuel droplets in air is studied for pressures in the range of 5-140 atm. Results indicate that the ambient gas pressure exerts significant control of droplet gasification and burning processes through its influence on fluid transport, gas-liquid interfacial thermodynamics, and chemical reactions. The droplet gasification rate increases progressively with pressure. However, the data for the overall burnout time exhibit a considerable change in the combustion mechanism at the critical pressure, mainly as a result of reduced mass diffusivity and latent heat of vaporization with increased pressure.

  1. Combustion of liquid fuel droplets in supercritical conditions

    NASA Technical Reports Server (NTRS)

    Shuen, J. S.; Yang, Vigor

    1991-01-01

    A comprehensive analysis of liquid-fuel droplet combustion in both sub- and super-critical environments has been conducted. The formulation is based on the complete conservation equations for both gas and liquid phases, and accommodates finite-rate chemical kinetics and a full treatment of liquid-vapor phase equilibrium at the droplet surface. The governing equations and the associated interface boundary conditions are solved numerically using a fully coupled, implicit scheme with the dual time-stepping integration technique. The model is capable of treating the entire droplet history, including the transition from the subcritical to the supercritical state. As a specific example, the combustion of n-pentane fuel droplets in air is studied for pressures of 5-140 atm. Results indicate that the ambient gas pressure exerts significant control of droplet gasification and burning processes through its influences on the fluid transport, gas/liquid interface thermodynamics, and chemical reactions. The droplet gasification rate increases progressively with pressure. However, the data for the overall burnout time exhibits a significant variation near the critical burning pressure, mainly as a result of reduced mass-diffusion rate and latent heat of vaporization with increased pressure. The influence of droplet size on the burning characteristics is also noted.

  2. Plasticized Polymer Composite Single-Ion Conductors for Lithium Batteries.

    PubMed

    Zhao, Hui; Asfour, Fadi; Fu, Yanbao; Jia, Zhe; Yuan, Wen; Bai, Ying; Ling, Min; Hu, Heyi; Baker, Gregory; Liu, Gao

    2015-09-01

    Lithium bis(trifluoromethane) sulfonamide (TFSI) is a promising electrolyte salt in lithium batteries, due to its good conductivity and high dissociation between the lithium cation and its anion. By tethering N-pentane trifluoromethane sulfonamide (C5NHTf), a TFSI analogue molecule, onto the surface of silica nanoparticle as a monolayer coverage should increase the Li(+) transference number to unity since anions bound to particles have reduced mobilities. Silica polymer composite has better mechanical property than that of the pure PEO. Analogously trifluoromethane sulfonic aminoethyl methacrylate (TfMA), a TFSI analogue vinyl monomer, was polymerized on silica nanoparticle surface as a multilayer coverage. Anchored polyelectrolytes to particle surfaces offer multiple sites for anions, and in principle the carrier concentration would increase arbitrarily and approach the carrier concentration of the bulk polyelectrolyte. Monolayer grafted nanoparticles have a lithium content of 1.2 × 10(-3) g Li/g, and multilayer grafted nanoparticles have a lithium content over an order higher at 2 × 10(-2) g Li/g. Electrolytes made from monolayer grafted particles exhibit a weak conductivity dependence on temperature, exhibiting an ionic conductivity in the range of 10(-6) S/cm when temperatures increase to 80 °C. While electrolytes made from multilayer grafted particles show a steep increase in conductivity with temperature with an ionic conductivity increase to 3 × 10(-5) S/cm at 80 °C, with an O/Li ratio of 32. PMID:26284984

  3. Bayesian parametrization of coarse-grain dissipative dynamics models.

    PubMed

    Dequidt, Alain; Solano Canchaya, Jose G

    2015-08-28

    We introduce a new bottom-up method for the optimization of dissipative coarse-grain models. The method is based on Bayesian optimization of the likelihood to reproduce a coarse-grained reference trajectory obtained from analysis of a higher resolution molecular dynamics trajectory. This new method is related to force matching techniques, but using the total force on each grain averaged on a coarse time step instead of instantaneous forces. It has the advantage of not being limited to pairwise short-range interactions in the coarse-grain model and also yields an estimation of the friction parameter controlling the dynamics. The theory supporting the method is exposed in a practical perspective, with an analytical solution for the optimal set of parameters. The method was first validated by using it on a system with a known optimum. The new method was then tested on a simple system: n-pentane. The local molecular structure of the optimized model is in excellent agreement with the reference system. An extension of the method allows to get also an excellent agreement for the equilibrium density. As for the dynamic properties, they are also very satisfactory, but more sensitive to the choice of the coarse-grain representation. The quality of the final force field depends on the definition of the coarse grain degrees of freedom and interactions. We consider this method as a serious alternative to other methods like iterative Boltzmann inversion, force matching, and Green-Kubo formulae. PMID:26328833

  4. Design of Radial Turbo-Expanders for Small Organic Rankine Cycle System

    NASA Astrophysics Data System (ADS)

    Arifin, M.; Pasek, A. D.

    2015-09-01

    This paper discusses the design of radial turbo-expanders for ORC systems. Firstly, the rotor blades were design and the geometry and the perfromance were calculated using several working fluid such as R134a, R143a, R245fa, n-Pentane, and R123. Then, a numerical study was carried out in the fluid flow area with R134a and R123 as the working fluid. Analyses were performed using Computational Fluid Dynamics (CFD) ANSYS CFX on two real gas models, with the k-epsilon and SST (shear stress transport) turbulence models. The results analysis shows the distribution of Mach number, pressure, velocity and temperature along the rotor blade of the radial turbo-expanders and estimation of performance at various operating conditions. CFD analysis show that if the flow area divided into 250,000 grid mesh, and using real gas model SST at steady state condition, 0.4 kg/s of mass flow rate, 15,000 rpm rotor speed, 5 bar inlet pressure, and 373K inlet temperature, the turbo expander produces 6.7 kW, and 5.5 kW of power when using R134a and R123 respectively.

  5. Vaporization and combustion of fuel droplets at supercritical conditions

    NASA Technical Reports Server (NTRS)

    Yang, Vigor

    1991-01-01

    Vaporization and combustion liquid-fuel droplets in both sub- and super-critical environments have been examined. The formulation is based on the complete conservation equations for both gas and liquid phases, and accommodates finite-rate chemical kinetics and a full treatment of liquid-vapor phase equilibrium at the droplet surface. The governing equations and the associated interface boundary conditions are solved numerically using a fully coupled, implicit scheme with the dual time-stepping integration technique. The model is capable of treating the entire droplet history, including the transition from the subcritical to the supercritical state. As a specific example, the combustion of n-pentane fuel droplets in air is studied for pressures of 5-140 atm. In addition, the dynamic responses of droplet vaporization and combustion to ambient-pressure oscillations are investigated. Results indicate that the droplet gasification and burning mechanisms depend greatly on the ambient pressure. In particular, a rapid enlargement of the vaporization and combustion responses occurs when the droplet surface reaches its critical point, mainly due to the strong variations of latent heat of vaporization and thermophysical properties at the critical state.

  6. Statistical optimization of process parameters for lipase-catalyzed synthesis of triethanolamine-based esterquats using response surface methodology in 2-liter bioreactor.

    PubMed

    Masoumi, Hamid Reza Fard; Basri, Mahiran; Kassim, Anuar; Abdullah, Dzulkefly Kuang; Abdollahi, Yadollah; Abd Gani, Siti Salwa; Rezaee, Malahat

    2013-01-01

    Lipase-catalyzed production of triethanolamine-based esterquat by esterification of oleic acid (OA) with triethanolamine (TEA) in n-hexane was performed in 2 L stirred-tank reactor. A set of experiments was designed by central composite design to process modeling and statistically evaluate the findings. Five independent process variables, including enzyme amount, reaction time, reaction temperature, substrates molar ratio of OA to TEA, and agitation speed, were studied under the given conditions designed by Design Expert software. Experimental data were examined for normality test before data processing stage and skewness and kurtosis indices were determined. The mathematical model developed was found to be adequate and statistically accurate to predict the optimum conversion of product. Response surface methodology with central composite design gave the best performance in this study, and the methodology as a whole has been proven to be adequate for the design and optimization of the enzymatic process. PMID:24324389

  7. Regulating Underwater Oil Adhesion on Superoleophobic Copper Films through Assembling n-Alkanoic Acids.

    PubMed

    Cheng, Zhongjun; Liu, Hongwei; Lai, Hua; Du, Ying; Fu, Kewei; Li, Chong; Yu, Jianxin; Zhang, Naiqing; Sun, Kening

    2015-09-16

    Controlling liquid adhesion on special wetting surface is significant in many practical applications. In this paper, an easy self-assembled monolayer technique was advanced to modify nanostructured copper substrates, and tunable adhesive underwater superoleophobic surfaces were prepared. The surface adhesion can be regulated by simply varying the chain length of the n-alkanoic acids, and the tunable adhesive properties can be ascribed to the combined action of surfaces nanostructures and related variation in surface chemistry. Meanwhile, the tunable ability is universal, and the oil-adhesion controllability is suitable to various oils including silicon oil, n-hexane, and chloroform. Finally, on the basis of the special tunable adhesive properties, some applications of our surfaces including droplet storage, transfer, mixing, and so on are also discussed. The paper offers a novel and simple method to prepare underwater superoleophobic surfaces with regulated adhesion, which can potentially be applied in numerous fields, for instance, biodetection, microreactors, and microfluidic devices. PMID:26307917

  8. Synthesis, characterization and hydrophobicity of silylated starch nanocrystal.

    PubMed

    Wei, Benxi; Sun, Binghua; Zhang, Bao; Long, Jie; Chen, Long; Tian, Yaoqi

    2016-01-20

    Starch nanocrystal (SNC) was silylated by hexadecyltrimethoxysilane (HDS) aiming to improve its hydrophobicity. HDS was firstly hydrolyzed in ethanol/water and then adsorbed onto SNC through hydrogen bonds, finally the long chain hydrocarbon was covalently linked to the surface of SNC through SiOC bonds which formed via the condensation reaction between hydroxyl and silanol groups. Due to the multilayer coverage of the hydrolyzed HDS, the long chain hydrocarbon crystalized on the surface of SNC and superimposed over the original A-type starch diffraction pattern. Both the hydrophobicity and hydrophobic stability were increased with the increase of the applied HDS. The contact angle of modified SNC increased from 43° to 119° as the applied HDS increased from 0% to 0.3% (v/v). The modification significantly improved its dispersibility in non-polar solvents and a homogenous suspension could be formed in acetone and n-hexane. PMID:26572463

  9. First phytochemical investigation of secondary metabolites of Euphorbia davidii Subils. and antiproliferative activity of its extracts.

    PubMed

    Rédei, Dóra; Kúsz, Norbert; Szabó, Máté; Pinke, Gyula; Zupkó, István; Hohmann, Judit

    2015-12-01

    The present work is the first phytochemical investigation of Euphorbia davidii Subils. After multistep separation process, three flavonoid glycosides were obtained from the ethyl acetate soluble fraction of the methanol extract of the whole plant. The structures of the isolated compounds were determined as kaempferol 3-O-rhamnoside, myricetin 3-O-rhamnoside, and quercetin 3-O-rhamnoside. Aqueous and organic extracts of the plant were screened in vitro for antiproliferative activity against HeLa (cervix epithelial adenocarcinoma), A431 (skin epidermoid carcinoma), A2780 (ovarian carcinoma) and MCF7 (breast epithelial adenocarcinoma) cells, using the MTT assay. n-Hexane and chloroform extracts demonstrated moderately dose-dependent cell growth inhibitory activity against all four cell lines. PMID:26616378

  10. Cytotoxic activity of some lichen extracts on murine and human cancer cell lines.

    PubMed

    Bézivin, C; Tomasi, S; Lohézic-Le Dévéhat, F; Boustie, J

    2003-01-01

    Eight lichens were extracted successively with n-hexane, diethyl ether and methanol using a Soxhlet process. The cytotoxic activity of the 24 lichen extracts was evaluated in vitro using two murine (the L1210: lymphocytic leukaemia, and the 3LL: Lewis lung carcinoma) and four human (the K-562: chronic myelogenous leukaemia, the U251: glioblastoma, the DU145: prostate carcinoma, and the MCF7: breast adenocarcinoma) cancer cell lines and non-cancerous cells, the Vero cell line (African green monkey kidney cell line). The MTT assay revealed significant cytotoxicity (IC50 < or = 20 microg/ml) on one of the tested cancer cell lines for at least one extract of each lichen species. Some extracts of Cladonia convoluta, Cladonia rangiformis, Parmelia caperata, Platismatia glauca and Ramalina cuspidata demonstrated interesting activities particularly on human cancer cell lines as good selectivity indices were recorded (SI > 3). PMID:13678234

  11. Fractionation analysis of manganese in Turkish hazelnuts (Corylus avellana L.) by inductively coupled plasma-mass spectrometry.

    PubMed

    Erdemir, Umran Seven; Gucer, Seref

    2014-11-01

    In this study, an analytical fractionation scheme based on water, diethyl ether, n-hexane, and methanol extractions has been developed to identify manganese-bound fractions. Additionally, in vitro simulated gastric and intestinal digestion, n-octanol extraction, and activated carbon adsorption were used to interpret the manganese-bound structures in hazelnuts in terms of bioaccessibility. The total content of manganese in the samples was determined by inductively coupled plasma-mass spectrometry after microwave-assisted digestion, and additional validation was performed using atomic absorption spectroscopy. Water fractions were further evaluated by high-performance liquid chromatography hyphenated to inductively coupled plasma-mass spectrometry for the identification of water-soluble manganese fractions in hazelnut samples. The limits of detection and quantification were 3.6 and 12.0 ?g L(-1), respectively, based on peak height. PMID:25310841

  12. Hydrophilic and hydrophobic nano-sized Mn{sub 3}O{sub 4} particles

    SciTech Connect

    Gibot, Pierre Laffont, Lydia

    2007-02-15

    Mn{sub 3}O{sub 4} Hausmanite nanoparticles were prepared in aqueous solution by using metallic salt and hydrazine as precursor and reducing agent, respectively. The crystallite sizes ranged from 10 to 20 nm and the particle diameter distribution was very narrow and estimated between 20 and 30 nm. Influence of some parameters such as temperature, time of reaction, surfactant nature was studied for a synthesis in an aqueous medium. The as-made manganese oxides particles could be dispersed in an organic solvent containing stabilizing agents, according to perform the synthesis in an H{sub 2}O/n-hexan two-phase medium. These nanoparticles were characterized by X-ray diffraction, infrared spectroscopy, scanning and transmission electron microscopies and nitrogen absorption measurements. - Graphical abstract: Hydrophobic nano-sized Mn{sub 3}O{sub 4} particles.

  13. In vitro biological screening of the stem of Desmodium elegans

    PubMed Central

    Khan, Arshad; Usman, Rabia; Rauf, Abdur; Wang, Ming-Liang; Muhammad, Naveed; Aman, Akhatar; Tahir, Taha Hussein Musa

    2013-01-01

    Objective To explore the medicinal importance of the stem of Desmodium elegans, methanolic extract, and its different solvent fractions were evaluated for brine shrimp lethality, insecticidal and phytotoxicity, antifungal, and antibacterial activities. Methods The methanolic extract and its solvent fractions were tested for cytotoxic, phytotoxic, insecticidal, antifungal, and antibacterial effects using our previous published protocols. Results The methanolic, DCM, ethyl acetate and n-butanol fractions exhibited insecticidal effect against Callosobruchus analis and Rhyzopertha dominic. The methanolic extract, n-hexane, DCM ethyl acetate and n-butanol showed 75, 85, 85, 65 and 5% phytotoxicity at the tested concentration of 500 µg/mL respectively. The solvent fractions (DCM and ethyl acetate) were effective against F. solani (10% and 20% inhibition respectively). All the tested samples were devoid of cytotoxic and antibacterial effects. Conclusion It was concluded that this plant can be practiced for control of weeds and insects. PMID:23998011

  14. Magnetic effects on the solvent properties investigated by molecular dynamics simulation

    NASA Astrophysics Data System (ADS)

    Moosavi, Fatemeh; Gholizadeh, Mostafa

    2014-03-01

    This paper investigates how an external constant magnetic field in the Z-direction affects the performance of a solvent. The molecular dynamics simulation comprised common inorganic and organic solvents including water, acetone, acetonitrile, toluene, and n-hexane at the ambient temperature and pressure. A static magnetic field applied in the simulation process is able to reduce the solvent mobility in the solution in order to enhance the solvent-solute reaction. Simulation results show that the diffusivity decreases because of increasing the effective interactions. Besides, magnetic field reduces the volume of the solvent and increases the strength of the hydrogen bonds by maximizing attractive electrostatic and vdW interactions caused by changes in the radial distribution function of the solvents. Hydrogen-bonding characteristics of solvents investigated by molecular dynamics simulations were evidence for the hydrogen bonding strength of O···H that is a more efficient intermolecular hydrogen-bonding in comparison with N···H.

  15. Hydrogenated Amorphous Silicon (a-Si:H) Colloids

    SciTech Connect

    Harris, Justin T.; Hueso, Jose L.; Korgel, Brian A.

    2010-12-14

    Colloidal particles of hydrogenated amorphous silicon (a-Si:H) were synthesized by decomposition of trisilane (Si{sub 3}H{sub 8}) in supercritical n-hexane (sc-hexane) at temperatures ranging from 380 to 550 °C. The reaction temperature, pressure and Si{sub 3}H{sub 8} concentration have a significant influence on the average particle size, Si bond order and hydrogen content. The particle diameter could be varied from 170 nm to 1.7 ?m, with hydrogen loadings between 10% and 58%. Raman spectroscopy of the particles revealed significant differences in Si bond order that correlated with hydrogen content, with the lowest reaction temperatures yielding particles with the least structural order and most associated hydrogen. Particles synthesized at temperatures higher than 420 °C had sufficient bond order to allow crystallization under the Raman laser probe.

  16. Synthesis and effect of fatty acid amides as friction modifiers in petroleum base stock.

    PubMed

    Khalkar, Sharmishtha; Bhowmick, DiptiNarayan; Pratap, Amit

    2013-01-01

    Fatty acid amides were prepared by using Lewis acid as a catalyst. The products from reaction was subjected to solvent extraction with chloroform and then followed by purification with n-hexane, ethanol and acetonitrile. Fatty acid amide, characterized by various physicochemical and tribological properties like wear scar, weld load and coefficient of friction. These compounds found good antiwear (AW) and extreme pressure (EP) additive. The addition of various EP and AW additives in lubricating oil is an important and effective way to reduce friction and wear. Fatty acid amides were used as antiwear and friction modifier additive and a comparative study was carried out for 1%, 3%, 5% additive blend with commercial petroleum base stocks 150N and 500N. PMID:24200937

  17. Viscosity of biniary mixtures. III. Tri- n-butylamine with alkanes and monoalkylamines at 303.15 and 313.15 K

    NASA Astrophysics Data System (ADS)

    Oswal, S. L.; Patel, S. G.

    1992-09-01

    Viscosities ? of seven binary systems of n-propylamine, n-butylamine, n-hexylamine, n-octylamine, n-hexane, n-octane, and isoctane (2,2,4-trimethylpentane) with tributylamine have been measured at 303.15 and 313.15 K with an Ubbelohde suspended-level viscometer. Based on Eyring's theory, values of excess Gibbs energy of activation ?G *E of viscous flow have been calculated. Deviations of viscosities from linear dependence on the mole fraction and values of ?G *E are attributed to the H-bonding and to the size of alkylamine and alkane molecules. The free volume theory of Prigogine-Flory-Patterson in combination with work by Bloomfield-Dewan has been used to estimate the excess viscosity ? ln ? and the terms corresponding to enthalpy, entropy, and free volume contributions for the present binary mixtures.

  18. Viscosity of binary mixtures. III. Tri-n-butylamine with alkanes and monoalkylamines at 303. 15 and 313. 15 K

    SciTech Connect

    Oswal, S.L.; Patel, S.G. )

    1992-09-01

    Viscosities [eta] of seven binary systems of n-propylamine, n-butylamine, n-hexylamine, n-octylamine, n-hexane, n-octane, and isoctane (2, 2, 4-trimethylpentane) with tributylamine have been measured at 303.15 and 313.15 K with an Ubbelohde suspended-level viscometer. Based on Eyring's theory, values of excess Gibbs energy of activation [delta]G[sup *E] of viscous flow have been calculated. Deviations of viscosities from linear dependence on the mole fraction and values of [delta]G[sup *E] are attributed to the H-bonding and to the size of alkylamine and alkane molecules. The free volume theory of Prigogine-Flory-Patterson in combination with work by Bloomfield-Dewan has been used to estimate the excess viscosity [delta]1n [eta] and the terms corresponding to enthalpy, entropy, and free volume contributions for the present binary mixtures. 25 refs., 7 figs., 7 tabs.

  19. Antimicrobial Activity of Trifoliate Orange (Poncirus trifoliate) Seed Extracts on Gram-Negative Food-borne Pathogens

    PubMed Central

    Kim, Seong Yeong; Shin, Kwang-Soon

    2012-01-01

    Trifoliate orange seed extracts (TSEs) were prepared from different solvents, water (TW), ethanol (TE), and n-hexane (TH), and assessed for their antimicrobial activities against six gram-negative food-borne pathogens (Escherichia coli KCTC 1039, Escherichia coli O157:H7 ATCC 43895, Salmonella Enteritidis ATCC 3311, Salmonella Typhimurium KCCM 11862, Shigella sonnei KCTC 2518, and Vibrio parahaemolyticus ATCC 17802). Among the tested TSEs, TE and TH showed a slight inhibition activity on V. parahaemolyticus ATCC 17802, but a good growth inhibition activity on Sal. Typhimurium KCCM 11862. TH and TE showed steady growth inhibition activity with increasing growth time after 6 hr when compared to the control (p<0.05). From these results, we confirmed the possibility of TH and TE as antimicrobial materials. PMID:24471089

  20. Batatins VIII-XI, glycolipid ester-type dimers from Ipomoea batatas.

    PubMed

    Rosas-Ramírez, Daniel; Pereda-Miranda, Rogelio

    2015-01-23

    Sweet potato (Ipomoea batatas) is native to the tropics of Central and South America, where many varieties have been consumed for more that 5000 years. In developing countries, this crop is a recognized effective food for fighting malnutrition. Purification of the minor lipophilic glicolipids found in the n-hexane-soluble resin glycosides from the white-skinned variety was performed by preparative-scale recycling HPLC. Application of column overload, peak shaving, heart cutting, and recycling techniques permitted the purification of four new oligosaccharide ester-type dimer derivatives of jalapinolic acid, batatins VIII-XI (1-4). The structural characterization of these complex lipo-oligosaccharides was performed through NMR spectroscopy and MS, indicating that batatins VIII-XI (1-4) possess an oligomeric structure consisting of two pentasaccharide units of the known simonic acid B. PMID:25531152