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Mechanism of pyrolysis of n-alkanes. 3. n-Hexane
Rumyantsev, A.N.; Oganesova, E.Yu.
The distribution of products from the pyrolysis of n-pentane and n-hexane, including comparisons between calculated and experimental data, was examined. Purity of the original n-hexane was 99.97% by weight. Reactor temperature was 660/sup 0/C. The feed was supplied by a micropump or was fed from an argon-pressurized metal cylinder. The number of primary and secondary radicals formed in the pyrolysis of n-hexane were determined by examining their decomposition paths in the state of chain propagation in a radical chain scheme. Calculated values for the isomerization of primary n-pentyl and n-hexyl radicals into secondary radicals, using the Arrhenius equation, are presented.
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)
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.
Rich n-heptane and diesel combustion in porous media
Pastore, A.; Mastorakos, E. [Department of Engineering, University of Cambridge, Cambridge CB2 1PZ (United Kingdom)
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)
Effects of strain rate on high-pressure nonpremixed n-heptane autoignition in counterflow
Shiling Liu; John C. Hewson; Jacqueline H. Chen; Heinz Pitsch
The effect of steady strain on the transient autoignition of n-heptane at high pressures is studied numerically with detailed chemistry and transport in a counterflow configuration. Skeletal and reduced n-heptane mechanisms are developed and validated against experiments over a range of pressure and stoichiometries. Two configurations are investigated using the skeletal mechanism. First, the effect of strain rate on multistage
Triplet xanthone in n-pentane: multiple emission from a single site
NASA Astrophysics Data System (ADS)
Griesser, Hans J.; Bramley, Richard
The three phosphorescence components of xanthone in n-pentane originate from three states of one solvated species: From the z sublevel of the second triplet state, of 3n? * origin, and from two widely split sublevels of the lowest triplet state, of 3?? * origin. Its z sublevel is thermally depleted across the spin-orbit mixing induced zero-field sublevel splitting of 15.1 cm -1.
Raman scattering spectroscopic study of n-pentane under high pressure.
Qiao, Erwei; Zheng, Haifei
The Raman spectroscopy of n-pentane was investigated in a Moissanite anvil cell from 0.07 GPa to 4.77 GPa at ambient temperature. The result shows that the CH3 symmetric stretching vibration (2877 cm(-1)) and asymmetric stretching vibration (2964 cm(-1)), the CH2 symmetric stretching vibration (2856 cm(-1)) and asymmetric stretching vibration (2935 cm(-1)), and -(CH2)n- in-phase twist mode (1303 cm(-1)) shifted to higher wavenumbers almost linearly with increasing pressure. Around 2.4 GPa an abrupt visible change took place, indicating a sort of phenomenon of freezing due to over-pressurization. In the pressure range of 2.84 to 4.77 GPa a high-pressure phase transition may occur in the crystallized n-pentane. By determining pressure with the method of solid-liquid coexistence, we concluded that the equilibrium freezing pressure of n-pentane is 1.90 +/- 0.05 GPa at 27 degrees C. PMID:15969810
Adsorption of n-pentane on mesoporous silica and adsorbent deformation.
Gor, Gennady Yu; Paris, Oskar; Prass, Johannes; Russo, PatrĒcia A; Ribeiro Carrott, M Manuela L; Neimark, Alexander V
Development of quantitative theory of adsorption-induced deformation is important, e.g., for enhanced coalbed methane recovery by CO2 injection. It is also promising for the interpretation of experimental measurements of elastic properties of porous solids. We study deformation of mesoporous silica by n-pentane adsorption. The shape of experimental strain isotherms for this system differs from the shape predicted by thermodynamic theory of adsorption-induced deformation. We show that this difference can be attributed to the difference of disjoining pressure isotherm, responsible for the solid-fluid interactions. We suggest the disjoining pressure isotherm suitable for n-pentane adsorption on silica and derive the parameters for this isotherm from experimental data of n-pentane adsorption on nonporous silica. We use this isotherm in the formalism of macroscopic theory of adsorption-induced deformation of mesoporous materials, thus extending this theory for the case of weak solid-fluid interactions. We employ the extended theory to calculate solvation pressure and strain isotherms for SBA-15 and MCM-41 silica and compare it with experimental data obtained from small-angle X-ray scattering. Theoretical predictions for MCM-41 are in good agreement with the experiment, but for SBA-15 they are only qualitative. This deviation suggests that the elastic modulus of SBA-15 may change during pore filling. PMID:23758155
In situ high-pressure and high-temperature experiments on n-heptane.
Qiao, Erwei; Zheng, Haifei; Long, Changxing
The Raman spectroscopy of n-heptane was investigated in a moissanite anvil cell at ambient temperatures and a diamond anvil cell under pressures of up to ~2000 MPa and at temperature range from 298 to 588 K. The results show that at room temperature the vibration modes, assigned to the symmetric and antisymmetric stretching of CH(3) and CH(2) stretching, shifted to higher frequency according to quasi-linearity with increasing pressure, and a liquid-solid phase transition occurred at near 1150 MPa. The high-temperature solidus line of n-heptane follows a quadratic function of P = 0.00737T(2) + 5.27977T - 1195.76556. Upon phase change, fitting the experimental data obtained in the temperature range of 183?412 K to the Clausius-Clapeyron equation allows one to define the thermodynamic parameters of n-heptane of dP/dT = 0.01474T + 5.27977. PMID:22449288
Ozone production by a dc corona discharge in air contaminated by n-heptane
NASA Astrophysics Data System (ADS)
Pekßrek, S.
Beneficial purposes of ozone such as elimination of odours, harmful bacteria and mildew can be used for transportation of food, fruits and vegetables with the aim to extend their storage life. To date the main technique used for this purpose in the transportation of these commodities, e.g. by trucks, was cooling. Here a combination of cooling together with the supply of ozone into containers with these commodities is considered. For these purposes we studied the effect of air contamination by n-heptane (part of automotive fuels) and humidity on ozone production by a dc hollow needle to mesh corona discharge. We found that, for both polarities of the needle electrode, addition of n-heptane to air (a) decreases ozone production; (b) causes discharge poisoning to occur at lower current than for air; (c) does not substantially influence the current for which the ozone production reaches the maximum. Finally the maximum ozone production for the discharge in air occurs for the same current as the maximum ozone production for the discharge contaminated by n-heptane. We also found that humidity decreases ozone production from air contaminated by n-heptane irrespective of the polarity of the coronating needle electrode. This dependence is stronger for the discharge with the needle biased positively.
Quaternary liquid-liquid equilibrium of n-heptane-toluene-o-xylene-propylene carbonate
Salem, A.B.S.H.; Hamad, E.Z.; Al-Naafa, M.A. (King Fahd Univ. of Petroleum and Minerals, Dhahran (Saudi Arabia). Chemical Engineering Dept.)
Liquid-liquid equilibrium data for the system n-heptane/toluene/o-xylene/propylene carbonate were obtained at 25 OC. Experimental tie line data were measured by gas chromatographic analysis. The UNIQUAC and NRTL models were used to predict the quaternary data from the corresponding ternary data. Agreement between the predictions and the experimental data was satisfactory.
Isochoric heat capacity of an n-hexane + water system
NASA Astrophysics Data System (ADS)
Bezgomonova, E. I.; Saidov, S. M.; Stepanov, G. V.
The isochoric heat capacity of an n-hexane + water system at water contents of 0.121, 0.166, 0.2, 0.234, 0.256, and 0.3 mole fraction is studied along different isochors at different temperatures in the 140 to 550 kg/m3 range of densities using a high-temperature adiabatic calorimeter designed at the Amirkhanov Institute of Physics. The tabulated values of isochoric heat capacity C v, x are presented for an H2O concentration of 0.3 mole fraction. The curves of liquid-liquid and liquid-gas phase equilibria are constructed.
Shocktube investigation of self-ignition of n-heptane - Air mixtures under engine relevant conditions
H. K. Ciezki; G. Adomeit
To determine self-ignition characteristics under conditions relevant to piston engines combustion, n-heptane - air mixtures have been investigated in a high-pressure shock tube without use of the customary heat bath dilution. The initial pressure has been varied between 3.2 and 42 bar and the initial temperature between 660 and 1,350 K while the equivalence ratio covers the region between 0.5
Ignition of turbulent swirling n-heptane spray flames using single and multiple sparks
T. Marchione; S. F. Ahmed; E. Mastorakos
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
Ignition of n-heptane pool by heated stagnating oxidizing flow
Wei Liu; Delin Zhu; Ning Wu; Chung K. Law
The ignition temperature of a liquid pool of n-heptane by heated oxidizer in a stagnation flow was experimentally determined for system pressures of 0.61¢3atm and pressure-weighted strain rates of 60¢350s?1. The surface of the liquid pool was maintained at a fixed location through continuous replenishment. The state of ignition was brought about, and monitored, by gradually increasing the oxidizer temperature.
[Spectroscopic measurement of intermediate free radicals of n-heptane in the combustion reaction].
Ye, Bin; Li, Ping; Zhang, Chang-hua; Wang, Li-dong; Tang, Hong-chang; Li, Xiang-yuan
Using an intensified spectroscopic detector CCD and a chemical shock tube, transient emission spectra of n-heptane during the reaction process of combustion were measured, with exposure time of 6 micros and a spectral range of 200 - 850 nm Experiments were conducted at an ignition temperature of 1 408 K and pressure of 2.0 atmos, with an initial fuel mole fraction of 1.0% and an equivalence ratio of 1.0. Measured emission bands were determined to be produced by OH, CH and C2 free radicals, which reveals that small OH, CH and C2 radicals are important intermediate products in the combustion process of n-heptane. Time-resolved spectra indicate that radical concentrations of OH, CH and C2 reached their peaks sharply; however, CH and C2 reduced and disappeared rapidly while the duration of OH was much longer in the reaction. This work provides experimental data for understanding the microscopic process and validating the mechanism of n-heptane combustion reaction. PMID:22715748
A model-free temperature-dependent conformational study of n-pentane in nematic liquid crystals.
Burnell, E Elliott; Weber, Adrian C J; Dong, Ronald Y; Meerts, W Leo; de Lange, Cornelis A
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. PMID:25591384
IRIS Toxicological Review and Summary Documents for N-Hexane (External Review Draft)
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...
Effects of temperature and pressure on asphaltene particle size distributions in crude oils diluted with n-pentane
Bent B. Nielsen; William Y. Svrcek; Anil K. Mehrotra
The effects of temperature (0--150 C) and pressure (0--5.6 MPa) on the size distribution of asphaltene particles (or agglomerates), formed as a result of diluting the crude oils with n-pentane, were studied using a modified laser particle analyzer. Four crude oils, ranging from an asphaltic condensate to a heavy oil-sand bitumen, were tested in this investigation. The average size of
Esterification kinetics of triglycerides in n-hexane catalyzed by an immobilized lipaseĀ
Gomez Ruiz, Alejandro
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...
Treatment of Benzene and n-Hexane Mixtures in Trickle-Bed Air Biofilters
Ashraf Aly Hassan; George A. Sorial
Trickle-bed air biofilters (TBABs) are suitable for treatment of hydrophilic volatile organic compounds, but they pose a challenge for hydrophobic compounds. Three laboratory-scale TBABs were used for the treatment of an airstream contaminated with different ratios of n-hexane and benzene mixtures. The ratios studied were 1:1, 2:1, and 1:3 n-hexane:benzene by volume. Each TBAB was operated at a pH of
Rate-ratio asymptotic analysis of autoignition of n-heptane in laminar nonpremixed flows
Seshadri, K. [Center for Energy Research, Department of Mechanical and Aerospace Engineering, University of California at San Diego, La Jolla, CA 92093-0411 (United States); Peters, N.; Paczko, G. [Institut fuer Technische Verbrennung, Rhein.-Westf. Technische Hochschule Aachen, 52058 Aachen (Germany)
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)
The influence of low atmospheric pressure on carbon monoxide of n-heptane pool fires.
Jun, Fang; Yu, Chun-Yu; Ran, Tu; Qiao, Li-Feng; Zhang, Yong-Ming; Wang, Jin-Jun
Qualitative theoretical analysis about air pressure influence upon the gas concentration of a fire plume was given, different scale n-heptane pool fires were conducted in a small and a standard compartment room in Lhasa and Hefei, respectively. The experimental results show that, in Lhasa, the average mass burning rates in the small room and the standard room both decrease, burning time increases at about 53% in small room and 45% in standard room more than in Hefei. Whereas for maximum changes of CO concentration, in the small room, in Lhasa, CO concentrations reach about twice bigger peak values at larger increase rates than in Hefei. While in the standard room, in Lhasa and Hefei, there are no significant changes for CO concentration, which agrees well with the theoretical analysis results. PMID:18054157
Quasi-isochoric p?T measurements and second virial coefficient of n-heptane
NASA Astrophysics Data System (ADS)
Millat, J.; Hendl, H.; Bich, E.
Quasi-isochoric p?T measurements on n-heptane vapor were carried out in the low density region using an improved apparatus that was originally proposed by Opel and Schaffenger ( Wiss. Z. Univ. Rostock N18:871, 1969). The experimental results extend over the temperature range between 350 and 600 K and the density range between 11.5 and 52.2 mol Ę m-3. Above 473 K a small but significant influence of decomposition was found. Accordingly, a correction scheme assuming a trace of decomposition products was applied to these data. Second virial coefficients were derived with an assumed maximum uncertainty of ▒3%.. The results are compared with others in the literature and used to develop an improved correlation function for the temperature dependence of B( T).
Soot formation modelling of n-heptane sprays under diesel engine conditions using the Conditional Moment Closure
Daraio, Chiara
1 Soot formation modelling of n-heptane sprays under diesel engine conditions using the Conditional-volume vessel under diesel engine conditions under different ambient densities (14.8 and 30 kg/m3 ) and ambient that the conditional moment closure approach is a promising framework for soot modelling under Diesel engine conditions
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...
Oxidation of 1-butanol and a mixture of n-heptane/1-butanol in a motored engine
Zhang, Yu.; Boehman, Andre L. [EMS Energy Institute, The Pennsylvania State University, University Park, PA 16802 (United States)
The oxidation of neat 1-butanol and a mixture of n-heptane and 1-butanol was studied in a modified CFR engine at an equivalence ratio of 0.25 and an intake temperature of 120 C. The engine compression ratio was gradually increased from the lowest point to the point where significant high temperature heat release was observed. Heat release analyses showed that no noticeable low temperature heat release behavior was observed from the oxidation of neat 1-butanol while the n-heptane/1-butanol mixture exhibited pronounced cool flame behavior. Species concentration profiles were obtained via GC-MS and GC-FID/TCD. Quantitative analyses of the reaction products from the oxidation of neat 1-butanol indicate that 1-butanol is consumed mainly through H-atom abstraction. Among the H-atom abstraction reactions, it is observed that the H-atom abstraction from the {alpha}-carbon of 1-butanol is particularly favored. The investigation on the oxidation of the mixture of n-heptane/1-butanol showed that the oxidation of 1-butanol is facilitated at low temperatures through the radical pool generated from the oxidation of n-heptane. (author)
Anisotropic spinŚlattice relaxation in the triplet state of naphtralene- h8 in n-pentane
NASA Astrophysics Data System (ADS)
Ghosh, Sanjib; Weers, Jeffry G.; Petrin, Michael; Maki, August H.
The temperature dependence of the individual spinŚlattice relaxation rate constants ( W ij) between the lowest triplet sublevels of naphthalene- h8 in a polycrystalline Shpol'skii matrix of n-pentane have been measured between 1.2 and 2.4 K in zero field. The total sublevel decay constants are evaluated and found to be independent of temperature. The W ij are found to be highly anisotropic, but the anisotropy pattern differs from that observed previously in a durene matrix.
Microstructures of capped ethylene oxide oligomers in water and n-hexane
Mangesh I. Chaudhari; Lawrence R. Pratt
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.
Direct numerical simulation of ignition in turbulent n-heptane liquid-fuel spray jets
Wang, Y.; Rutland, C.J. [Department of Mechanical Engineering, University of Wisconsin-Madison, WI 53706 (United States)
Direct numerical simulation was used for fundamental studies of the ignition of turbulent n-heptane liquid-fuel spray jets. A chemistry mechanism with 33 species and 64 reactions was adopted to describe the chemical reactions. The Eulerian method is employed to solve the carrier-gas flow field and the Lagrangian method is used to track the liquid-fuel droplets. Two-way coupling interaction is considered through the exchange of mass, momentum, and energy between the carrier-gas fluid and the liquid-fuel spray. The initial carrier-gas temperature was 1500 K. Six cases were simulated with different droplet radii (from 10 to 30 {mu}m) and two initial velocities (100 and 150 m/s). From the simulations, it was found that evaporative cooling and turbulence mixing play important roles in the ignition of liquid-fuel spray jets. Ignition first occurs at the edges of the jets where the fuel mixture is lean, and the scalar dissipation rate and the vorticity magnitude are very low. For smaller droplets, ignition occurs later than for larger droplets due to increased evaporative cooling. Higher initial droplet velocity enhances turbulence mixing and evaporative cooling. For smaller droplets, higher initial droplet velocity causes the ignition to occur earlier, whereas for larger droplets, higher initial droplet velocity delays the ignition time. (author)
Cracking of n-heptane on a CrHNaY zeolite catalyst. The network of the reaction
A. Lopez Agudo; A. Asensio; A. Corma
The cracking of n-heptane has been studied at 400, 450, and 470┬░C over a CrHNaY zeolite catalyst using a tubular packed-bed reactor. The concept of Optimum Performance Envelope was used in order to identify which of the observed reaction products are primary and which are secondary. In this way the initial selectivity values for all primary products have been calculated
Antipyretic and anticonvulsant activity of n-hexane fraction of Viola betonicifolia
Muhammad, Naveed; Saeed, Muhammad; Khan, Haroon; Raziq, Naila; Halimi, Syed Muhammad Ashhad
Objective To investigate the antipyretic and anticonvulsant activities of n-hexane fraction of Viola betonicifolia (V. betonicifolia). Methods The antipyretic effect was scrutinized using brewer's yeast induced pyrexia and anticonvlsion effect was tested using pentylenetetrazol and strychnine induced convulsion in mice. Results N-hexane fraction of V. betonicifolia demonstrated highly significant antipyretic activity during various assessment times (1-5 h) when challenged in yeast induced pyrexia test. The effect was in a dose dependent manner with maximum attenuation (82.50%) observed at 300 mg/kg i.p. When tested in pentylenetetrazol induced convulsion test, the 1st stage (Ear and facial twitching) and 2nd stage (Convulsive wave through the body) was 100% protected during 24 h at all the test doses (300, 400 and 500 mg/kg i.p.), while the latency time of remaining stages was significantly increased. The maximum effect was observed by n-hexane fraction of V. betonicifolia at 400 and 500 mg/kg i.p., as the latency time for generalized clonic-tonic seizure (5th stage) was increased up to 25.34 min. However, n-hexane fraction of V. betonicifolia had no protection in strychnine induced convulsion test. Conclusions In conclusion, phytopharmacological studies provide scientific foundation to the folk uses of the plant in the treatment of pyrexia and neurological disorders. PMID:23620851
Morphology of C60 decagonal crystals grown from n-hexane
NASA Astrophysics Data System (ADS)
Agafonov, V.; Ceolin, R.; Moret, R.; Andre, D.; Dworkin, A.; Szwarc, H.; Fabre, C.; Rassat, A.; Cense, J. M.; Zahab, A.
Ten-sided prismatic crystals of C60 grown by evaporation of n-hexane solutions have been characterized by SEM and X-ray diffraction. Various unusual morphologies have been observed. X-ray precession photographs confirm the decagonal symmetry and they are analyzed by means of twinning of monoclinic variants related by pi/5 rotations. Possible twinning mechanisms are discussed.
Separation of n-hexane¢ethyl acetate mixtures by azeotropic batch distillation with heterogeneous entrainers
I. Rodriguez-Donis; J. Acosta-Esquijarosa; V. Gerbaud; E. Pardillo-Fondevila; X. Joulia
In this article, a systematic study of the separation of the n-hexane¢ethyl acetate mixture with an entrainer by heterogeneous azeotropic batch distillation is performed. Based upon the thermodynamic behaviour of the ternary mixtures, potential entrainers partially miscible with one or two original azeotropic components are chosen. In all cases, the entrainer adds a heterogeneous binary or ternary azeotrope that is
Communication: Molecular dynamics and (1)H NMR of n-hexane in liquid crystals.
Weber, Adrian C J; Burnell, E Elliott; Meerts, W Leo; de Lange, Cornelis A; Dong, Ronald Y; Muccioli, Luca; Pizzirusso, Antonio; Zannoni, Claudio
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. PMID:26156458
Measurement and correlation of solid¢liquid equilibria of Irganox 1010 with n-hexane
Dongwei Wei; Limei Chen; Jingjing Xu; Fusheng Li
Solid¢liquid equilibria (SLE) for the binary mixtures of Irganox 1010 with n-hexane have been measured using a method in which an excess amount of solute was equilibrated with the alkane solution. The liquid concentrations of the Irganox 1010 in the saturated solution were analyzed by UV spectrometry. Activity coefficients for Irganox 1010 have been calculated by means of the Wilson,
Characterization of n-Hexane sub-fraction of Bridelia micrantha (Berth) and its antimycobacterium activity
Background Tuberculosis, caused by Mycobacterium tuberculosis (MTB), is the most notified disease in the world. Development of resistance to first line drugs by MTB is a public health concern. As a result, there is the search for new and novel sources of antimycobacterial drugs for example from medicinal plants. In this study we determined the in vitro antimycobacterial activity of n-Hexane sub-fraction from Bridelia micrantha (Berth) against MTB H37Ra and a clinical isolate resistant to all five first-line antituberculosis drugs. Methods The antimycobacterial activity of the n-Hexane sub-fraction of ethyl acetate fractions from acetone extracts of B. micrantha barks was evaluated using the resazurin microplate assay against two MTB isolates. Bioassay-guided fractionation of the ethyl acetate fraction was performed using 100% n-Hexane and Chloroform/Methanol (99:1) as solvents in order of increasing polarity by column chromatography and Resazurin microtiter plate assay for susceptibility tests. Results The n-Hexane fraction showed 20% inhibition of MTB H37Ra and almost 35% inhibition of an MTB isolate resistant to all first-line drugs at 10 ?g/mL. GC/MS analysis of the fraction resulted in the identification of twenty-four constituents representing 60.5% of the fraction. Some of the 24 compounds detected included Benzene, 1.3-bis (3-phenoxyphenoxy (13.51%), 2-pinen-4-one (10.03%), N(b)-benzyl-14-(carboxymethyl) (6.35%) and the least detected compound was linalool (0.2%). Conclusions The results show that the n-Hexane fraction of B. micrantha has antimycobacterial activity. PMID:21481267
The chemical influence of CO and H2 addition on the auto-ignition of n-heptane\\/air mixtures is investigated numerically. This work is motivated by the need for a precise control of auto-ignition during the compression stroke of Homogeneous Charge Compression Ignition (HCCI) engines. The numerical simulations are performed using three detailed mechanisms for n-heptane in order to ensure that the results are
Combustion characteristics and influential factors of isooctane active-thermal atmosphere combustion assisted by two-stage reaction of n-heptane
Lu, Xingcai; Ji, Libin; Ma, Junjun; Zhou, Xiaoxin; Huang, Zhen [Key Lab. for Power Machinery and Engineering of MOE, Shanghai Jiao Tong University, 200240 Shanghai (China)
This paper presents an experimental study on the isooctane active-thermal atmosphere combustion (ATAC) which is assisted by two-stage reaction of n-heptane. The active-thermal atmosphere is created by low- and high-temperature reactions of n-heptane which is injected at intake port, and isooctane is directly injected into combustion chamber near the top dead center. The effects of isooctane injection timing, active-thermal atmosphere intensity, overall equivalence ratio, and premixed ratio on combustion characteristics and emissions are investigated. The experimental results reveal that, the isooctane ignition and combustion can be classified to thermal atmosphere combustion, active atmosphere combustion, and active-thermal atmosphere combustion respectively according to the extent of n-heptane oxidation as well as effects of isooctane quenching and charge cooling. n-Heptane equivalence ratio, isooctane equivalence ratio and isooctane delivery advance angle are major control parameters. In one combustion cycle, the isooctane ignited and burned after those of n-heptane, and then this combustion phenomenon can also be named as dual-fuel sequential combustion (DFSC). The ignition timing of the overall combustion event is mainly determined by n-heptane equivalence ratio and can be controlled in flexibility by simultaneously adjusting isooctane equivalence ratio. The isooctane ignition regime, overall thermal efficiency, and NO{sub x} emissions show strong sensitivity to the fuel delivery advance angle between 20 CA BTDC and 25 CA BTDC. (author)
Formulation reproducing the ignition delays simulated by a detailed mechanism: Application to n-heptane combustion
Imbert, Bruno [LENI, IGM, STI, EPFL, Station 9, CH-1015 Lausanne (Switzerland); Lafosse, Fabien; Catoire, Laurent; Paillard, Claude-Etienne [ICARE, CNRS, and University of Orleans, 1C Av. de la Recherche Scientifique, F-45067 Orleans (France); Khasainov, Boris [LCD, CNRS, ENSMA, 1 Av. Clement Ader, F-86961 Futuroscope (France)
This article is part of the project to model the kinetics of high-temperature combustions, occurring behind shock waves and in detonation waves. The ''conventional'' semi-empirical correlations of ignition delays have been reformulated, by keeping the Arrhenius equation form. It is shown how a polynomial with 3{sup N} coefficients (where N element of is the number of adjustable kinetic parameters, likely to be simultaneously chosen among the temperature T, the pressure P, the inert fraction X{sub Ar}, and the equivalence ratio {phi}) can reproduce the delays predicted by the Curran et al. [H.J. Curran, P. Gaffuri, W.J. Pitz, C.K. Westbrook, Combust. Flame 129 (2002) 253-280] detailed mechanism (565 species and 2538 reactions), over a wide range of conditions (comparable with the validity domain). The deviations between the simulated times and their fits (typically 1%) are definitely lower than the uncertainties related to the mechanism (at least 25%). In addition, using this new formalism to evaluate these durations is about 10{sup 6} times faster than simulating them with SENKIN (CHEMKIN III package) and only 10 times slower than using the classical correlations. The adaptation of the traditional method for predicting delays is interesting for modeling, because those performances are difficult to obtain simultaneously with other reduction methods (either purely mathematical, chemical, or even mixed). After a physical and mathematical justification of the proposed formalism, some of its potentialities for n-heptane combustion are presented. In particular, the trends of simulated delays and activation energies are shown for {sub T} {sub element} {sub of} {sub [1500} {sub K,1900} {sub K},} {sub P} {sub element} {sub of} {sub [10kPa,1MPa]}, X{sub Ar} element of [0,0.7], and {phi} element of {sub [0.25,4.0]}. (author)
Effect of Pressure on Absorption Spectra of Lycopene in n-Hexane and CS2 Solvents
NASA Astrophysics Data System (ADS)
Zhang, Wei; Liu, Wei-Long; Zheng, Zhi-Ren; Huo, Ming-Ming; Li, Ai-Hua; Yang, Bin
The absorption spectra of lycopene in n-hexane and CS2 are measured under high pressure and the results are compared with ?-carotene. In the lower pressure range, the deviation from the linear dependence on the Bayliss parameter (BP) for ?-carotene is more visible than that for lycopene. With the further increase of the solvent BP, the 0-0 bands of lycopene and ?-carotene red shift at almost the same rate in n-hexane; however, the 0-0 band of lycopene red shifts slower than that of ?-carotene in CS2. The origins of these diversities are discussed taking into account the dispersion interactions and structures of solute and solvent molecules.
Ignition of turbulent swirling n-heptane spray flames using single and multiple sparks
Marchionea, T.; Ahmeda, S.F.; Mastorakos, E. [Department of Engineering, University of Cambridge (United Kingdom)
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)
Inhalation developmental toxicology studies: Teratology study of n-hexane in mice: Final report
Mast, T.J.; Decker, J.R.; Stoney, K.H.; Westerberg, R.B.; Evanoff, J.J.; Rommereim, R.L.; Weigel, R.J.
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.
Inhalation developmental toxicology studies: Teratology study of n-hexane in rats: Final report
Mast, T.J.
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.
Experimental study and chemical analysis of n-heptane homogeneous charge compression ignition combustion with port injection of reaction inhibitors
Lue, Xingcai; Ji, Libin; Zu, Linlin; Hou, Yuchun; Huang, Cheng; Huang, Zhen [School of Mechanical and Power Engineering, Shanghai Jiaotong University, Shanghai (China)
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)
In vitro antioxidant activity and HPTLC determination of n-hexane extract of Emilia sonchifolia (L.)DC.
Sophia, D; Ragavendran, P; Arulraj, C; Gopalakrishnan, V K
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
Effects of chronic n-hexane exposure on nervous system-specific and muscle-specific proteins
Jian Huang; Kanefusa Kato; Eiji Shibata; Kimiya Sugimura; Naomi Hisanaga; Yuichiro Ono; Yasuhiro Takeuchi I
Two kinds of nervous system-specific and muscle-specific proteins, enolase and S-100 protein, were quantitatively determined in peripheral nerves and skeletal muscles of rats chronically exposed to a neurotoxic solvent Ś n-hexane. Three groups of animals were exposed to n-hexane vapor at three different solvent concentrations (500 ppm, 1200 ppm, 3000 ppm) for 12 h\\/day, 7 days\\/ week for 16 weeks.
Molecular dynamics simulations of n-hexane at 1-butyl-3-methylimidazolium bis(trifluoromethylsulfonyl) imide interface
NASA Astrophysics Data System (ADS)
LĒsal, Martin; Izßk, Pavel
Molecular dynamics simulations of n-hexane adsorbed onto the interface of 1-butyl-3-methylimidazolium bis(trifluoromethylsulfonyl) imide ([bmim][Tf2N]) are performed at three n-hexane surface densities, ranged from 0.7 to 2.3 ?mol/m2 at 300 K. For [bmim][Tf2N] 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][Tf2N]/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.
A comprehensive skeletal mechanism for the oxidation of n-heptane generated by chemistry-guided reduction
Zeuch, Thomas [Institut fuer Physikalische Chemie, Tammannstrasse 6, 37077 Goettingen (Germany); Moreac, Gladys [Renault, 1, avenue du Golf, 78288 Guyancourt cedex (France); Ahmed, Syed Sayeed; Mauss, Fabian [Lehrstuhl fuer Thermodynamik und Thermische Verfahrenstechnik, Sielower Strasse 12, 03044 Cottbus (Germany)
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)
Mix and print: fast optimization of mesoporous CuCeZrOw for catalytic oxidation of n-hexane.
Huang, Fenfen; Wang, Shenliang; Yi, Wuzhong; Zou, Shihui; Chen, Changlei; Xiao, Liping; Liu, Xiaonao; Fan, Jie
Fast optimization of mesoporous ternary metal oxide (CuCeZrOw) catalysts for n-hexane oxidation is achieved via a newly developed combinatorial approach based on ink-jet printing assisted synthesis and multi-dimensional group testing. PMID:25872748
Linear time reduction of large kinetic mechanisms with directed relation graph: n-Heptane and iso-octane
Lu, Tianfeng; Law, Chung K. [Department of Mechanical and Aerospace Engineering, Princeton University, Princeton, NJ 08544 (United States)
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.
Catalytic properties in n-heptane reforming of Pt¢Sn and Pt¢Ir¢Sn\\/Al 2O 3 catalysts prepared by surface redox reaction
Florence Epron; Christelle Carnevillier; Patrice Marķcot
Multimetallic Pt¢Ir¢Sn\\/Al2O3 catalysts, prepared by surface redox reaction, were tested in the conversion of n-heptane, used as model reaction of paraffin dehydrocyclization, under industrial-type conditions. Their catalytic performances were measured after 5 and 65h of reaction in order to evaluate the stability of the catalysts, and compared to those of a well-known Pt¢Sn bimetallic catalyst as a function of the
Y zeolite from kaolin taken in Yen Bai-Vietnam: Synthesis, characterization and catalytic activity for the cracking of n-heptane
Ta Ngoc Don; Vu Dao Thang; Pham Thanh Huyen; Pham Minh Hao; Nguyen Khanh Dieu Hong
This paper is concerned with the synthesis of Y zeolite with SiO2\\/Al2O3 ratio of 4.5 from kaolin taken in Yen Bai-Vietnam and their catalytic activity for the cracking of n-heptane. The synthesized sample (NaY1) showed the Y zeolite crystallinity of 53% and P1 zeolite crystallinity of 32%, and exhibited good thermal stability up 880░C. The activity and the stability of
Droplet-droplet interactions investigated using a combination of electrochemical and dynamic light scattering techniques. The case of water/BHDC/benzene:n-heptane system.
Florez Tabares, Jußn Sebastißn; Correa, N Mariano; Silber, Juana J; Sereno, Leonides E; Molina, Patricia G
In this contribution the electrochemistry of [Fe(CN)6](4-/3-) as the probe molecule was investigated in benzyl-n-hexadecyldimethylammonium chloride (BHDC) reverse micelles (RMs) varying the composition of the external solvent (benzene:n-heptane mixtures) and the surfactant concentration, at a fixed water content and probe concentration. The electrochemical and dynamic light scattering results show that in water/BHDC/benzene:n-heptane systems the aggregate sizes increase on increasing BHDC concentration. This behavior was unexpected since it is known that for water/BHDC/benzene RM systems keeping the water content constant and the surfactant concentration below 0.2 M, the droplet sizes are independent of the concentration of the surfactant. We explain the results considering that on changing the external solvent to benzene:n-heptane mixtures, RMs tend to associate in clusters and equilibrium between free RMs and droplet clusters is established. A model is presented which, using electrochemical and dynamic light scattering data, allows calculating the aggregation number of the RMs, the number of RMs that form the droplet clusters and the standard electron transfer heterogeneous rate constant. PMID:25727358
Experimental Study of the Density and Viscosity of n-Heptane at Temperatures from 298 K to 470 K and Pressure upto 245 MPa
NASA Astrophysics Data System (ADS)
Sagdeev, D. I.; Fomina, M. G.; Mukhamedzyanov, G. Kh.; Abdulagatov, I. M.
The density and viscosity of n-heptane have been simultaneously measured over the temperature range from 298 K to 470 K and at pressures up to 245 MPa using the hydrostatic weighing and falling-body techniques, respectively. The expanded uncertainty of the density, pressure, temperature, and viscosity measurements at the 95 % confidence level with a coverage factor of k= 2 is estimated to be 0.15 % to 0.30 %, 0.05 %, 0.02 K, and 1.5 % to 2.0 % (depending on temperature and pressure ranges), respectively. The measured densities were used to develop a Tait-type equation of state for liquid n-heptane. Theoretically based Arrhenius-Andrade and Vogel-Tamman-Fulcher type equations with pressure-dependent coefficients were used to describe the temperature and pressure dependences of the measured viscosities for liquid n-heptane. The measured values of the density and viscosity were compared in detail with reported data and with the values calculated from a reference EOS and correlation models for the viscosity.
Hydroconversion of hydrocarbons over Ru-containing supported catalysts prepared by metal vapor method
Vagif M Akhmedov; Soliman H Al-Khowaiter
Some mono- and bimetallic-supported Ru\\/ZSM-5, Ru¢Re\\/ZSM-5, Ru¢Rh\\/ZSM-5, Ni¢Ru\\/ZSM-5 and Ru¢Ni\\/ZSM-5 catalysts were prepared by metal vapor method. The carbon¢carbon cleavage activity and the selectivity of prepared catalysts were investigated in hydroconversion of alkanes (n-pentane, n-hexane, n-heptane, 2-methylpentane) and cycloalkanes (cyclopentane, cyclohexane, methylcyclopentane). These catalysts demonstrate extremely high C¢C bond splitting activity in tested hydrocarbons. The magnitude of the effect for
On the properties of methylbenzoate/n-hexane mixed solvents: a theoretical and experimental study.
Aparicio, Santiago; Alcalde, Rafael; Davila, MarĒa J; GarcĒa, Bego±a; Leal, Josķ M
This paper reports on an experimental and theoretical study of methylbenzoate/n-hexane mixed solvents as a function of pressure and temperature in the whole composition range. We have measured the pressure-volume-temperature (PVT) behavior of these fluids over wide temperature and pressure ranges; from the experimental data, relevant derived coefficients required for the fluid's characterization were calculated. The structure of mixed fluids was analyzed from macroscopic data according to excess and mixing properties. The statistical associating fluid theory (SAFT) and perturbed chain (PC)-SAFT molecularly based equations of state were used to predict the PVT behavior with model parameters for pure fluids fitted from correlation of available saturation literature data. The results provided by the PC-SAFT equation of state were clearly superior. Using the fitted PC-SAFT parameters, the global phase behavior of the mixture was predicted, and a type I pattern was inferred according to the van Konynenburg systematic. The molecular level structure was studied through classical molecular dynamics simulations in the NPT ensemble using the optimized potential for liquid simulations (all atom version) (OPLS-AA) force field. Molecular dynamics provides, on one hand, theoretical values of thermophysical properties, which are compared with the experimental ones to check the quality of simulations, and, on the other hand, valuable molecular level structural and dynamic information. Based on both macroscopic and microscopic studies, fluid structure was inferred. PMID:18373359
First observation of alkyne radical anions by electron spin resonance spectroscopy: Hexyne/ n -hexane mixed crystals
Matsuura, K.; Muto, H. (Government Industrial Research Institute, Nagoya, Hirate-cho, Kita-ku, Nagoya, 462, Japan (JP))
The radical anions of alkynes have been first observed by electron spin resonance spectroscopy following alkene anions previously studied. Hexyne radical anions were formed in 1-, 2-, or 3-hexyne/{ital n}--hexane mixed crystals irradiated at 4.2 or 77 K. The characters of the anions were as follows; (a) the {alpha}-proton hyperfine coupling is very large ({similar to}4.5 mT for the 1-hexyne anion), (b) the {beta}-proton couplings are very small ({similar to}1.0 mT for C--H{sub {beta}} proton with the conformational angle of 0{degree}), and (c) the radicals show a negative {ital g} shift (2.0014). From these observations, it was found that the anions have a nonlinear(bent) molecule structure in the anticonfiguration ({ital trans} C--C{equivalent to}C--C) with the bend angle {similar to}60{degree}, and that the unpaired electron orbital is approximately composed of the anticombination of the {ital sp}{sub 2} hybrid orbitals of the C{equivalent to}C carbon atoms. A discussion based on complete neglect of differential overlap (CNDO) molecular orbital (MO) calculations was given for the observed negative {ital g} shift, which was shown to be characteristic of the alkyne anions which have a high-lying unpaired electron orbital and an antibonding 2{ital p}--2{ital p} {pi} carbon orbital just above it on the upper energy side.
Calculating the Krichevsky function and parameter for an n-hexane + water system from direct densitometric measurements
NASA Astrophysics Data System (ADS)
Rasulov, S. M.; Orakova, S. M.; Abdulagatov, I. M.
Based on experimental pVTx data, a theoretical study of the thermodynamic properties of a binary n-hexane + water system is performed for ten water concentrations (0.166, 0.201, 0.234, 0.237, 0.347, 0.615, 0.827, 0.918, 0.935, and 0.964 mole fractions of H2O) along different isochors. Constant volume piezometer measurements are made in the temperature, density, and pressure intervals of 303.65-690.55 K, 66.87-801.20 kg/m3, and 65.7 MPa. Based on the pVTx data and using different methods, the Krichevsky parameter is determined near the critical properties of the pure solvent ( n-hexane or water).
Quantitative determination of cyfluthrin in n-hexane by terahertz time-domain spectroscopy with chemometrics methods
Yuefang Hua; Hongjian Zhang; Hongliang Zhou
Terahertz time-domain spectroscopy (THz-TDS) was used for the detection of cyfluthrin content in N-hexane solvent with the concentration range of 0.5-10 mug\\/mL. The absorbance of the solution form cyfluthrin was obtained in the frequency range between 0.5-1.5 THz. Two kinds of multivariate linear regression models were then built between the absorbance and the concentration of 15 samples, using partial least
Extraction of surfactin from fermentation broth with n-hexane in microporous PVDF hollow fibers: Significance of membrane adsorption
Huei-Li Chen; Ruey-Shin Juang
In order to avoid foaming behavior and the formation of stable emulsions in traditional extraction, non-dispersive extraction of surfactin from the fermentation broth of Bacillus subtilis ATCC 21332 culture with n-hexane was studied in microporous polyvinylidene fluoride (PVDF, pore size 0.2?m) hollow fiber module. In this work, the broth was pretreated by acid precipitation and the precipitate was then dissolved
The effect of voids and dilution on n-hexane oxidation over a VMgO catalyst
Holger B. Friedrich; Nishlan Govender; Mfanwenkosi R. Mathebula
The conversion of n-hexane has been studied over magnesium orthovanadate (Mg3V2O8). This work illustrates some of the problems associated with alkane activation and subsequent conversion to more valuable products with respect to location of voids and the catalyst in the reactor. The effect of differently packed reactors and dilution factors on the product profile was investigated at a constant gas
Biological Exposure Indices of Pyrrole Adducts in Serum and Urine for Hazard Assessment of n-Hexane Exposure
Yin, Hongyin; Zhang, Chunling; Guo, Ying; Shao, Xiaoying; Zeng, Tao; Zhao, Xiulan; Xie, Keqin
Background Pyrrole adducts might be used as a biomarker for monitoring occupational exposure to n-hexane, but the Biological Exposure Indices of pyrrole adducts in serum and urine are still unknown. The current study was designed to investigate the biological exposure limit of pyrrole adducts for hazard assessment of n-hexane. Methods Male Wistar rats were given daily dose of 500, 1000, 1500, 2000, 4000 mg/kg bw n-hexane by gavage for 24 weeks. The levels of pyrrole adducts in serum and urine were determined at 8, 24 hours postdose once a week. The Biological Exposure Indices was evaluated by neurological evaluation and the levels of pyrrole adducts. The difference in pyrrole adducts formation between humans and rats were estimated by using in vitro test. Results Dose-dependent effects were observed between the doses of n-hexane and pyrrole adducts in serum and urine, and the levels of pyrrole adduct in serum and urine approached a plateau at week 4. There was a significantly negative correlation between the time to paralysis and the level of pyrrole adducts in serum and urine, while a positive correlation between gait score and levels of pyrrole adducts in serum and urine was observed. In vitro, pyrrole adducts formed in human serum was about two times more than those in rat serum at the same level of 2,5-HD. Conclusion It was concluded that the BEIs of pyrrole adducts in humans were 23.1▒5.91 nmol/ml in serum 8 h postdose, 11.7▒2.64 nmol/ml in serum 24 h postdose, 253.8▒36.3 nmol/ml in urine 8 h postdose and 54.6▒15.42 nmol/ml in urine 24 h postdose. PMID:24465904
Temperature dependence of surface tension of 2-methyl-1-propanol and 2-methyl-2-propanol+n-hexane mixtures
Beatriz Giner; Isabel Bandrķs; Ignacio Giner; Diego F. Monta±o; M. Carmen L¾pez
Surface tensions of binary mixtures of 2-methyl-1-propanol or 2-methyl-2-propanol with n-hexane have been measured in the temperature range 283.15 K¢313.15 K for mixtures containing 2-methyl-1-propanol and from 298.15 K to 313.15 K for mixtures formed by 2-methyl-2-propanol, with a drop volume tensiometer. The corresponding surface tension deviations have been calculated and correlated. Using the temperature dependence of surface tensions, the
Temperature dependence of the dual phosphorescence from xanthone in n-hexane matrices
NASA Astrophysics Data System (ADS)
Vala, Martin; Hurst, Jerry; Trabjerg, Ib
The phosphoresence spectrum and lifetime of xanthone embedded in an n-hexane matrix has been investigated as a function of temperature (1Ę6-100 K). Vibrational analyses of the spectra reveal that emission occurs from three sites, two of which are dominant. Emission from one site (B) occurs from the 3n?* state of a planar xanthone molecule and is characterized by strong totally symmetric carbonyl stretching vibrations and a short lifetime (2Ę4 ms). Emission from the other site (C) is shown to arise from the 3??* state of an out-of-plane distorted xanthone molecule. It displays a vibrational structure rich in modes of a1, b1, and b2 (C2v notation) symmetry and a long lifetime (115 ms). Both direct spin orbit coupling via configurational mixing of the n?* and ??* states due to the non-planarity of the molecule in its 3??* state and spin-orbit vibronic interaction involving 3A1(??*)-1A2(n?*) spin-orbit and 1A2(n?*)-1B2(??*) vibronic interaction via out-of-plane b1 vibrations are shown to be responsible for the C site emission intensity. Vibronic mixing between the 3??* and 3n?* states is not important. With increasing temperature, the phosphorescence intensity from the B site (3n?*) emitters increases at first, reaches a maximum at ś20 K and then decreases. The C site (3??*) intensity simply decreases with rising temperature. At a given temperature, the phosphorescence lifetimes are identical and exponential for all emission bands regardless of site origin. These observations indicate an equilibrium between emitters in the two sites throughout the lattice. A phonon-assisted energy transfer mechanism is proposed to account for these observations.
Electrophysiological follow-up of patients with chronic peripheral neuropathy induced by occupational intoxication with n-hexane.
Wang, Cheng; Chen, Shijiu; Wang, Zengtao
The aim of this study is to characterize and dynamically monitor the progress of peripheral neuropathy induced by n-hexane by electromyography and nerve conduction velocity (NCV-EMG). Twenty-five patients with n-hexane poisoning from an electronic company were investigated in the year 2009. The occupational history of these workers was collected, and toxic substance exposure was identified. Neurologic inspection and regular NCV-EMG inspection were performed for all patients upon hospital admission and after 3, 6, and 12 months of treatment. NCV-EMG results shown that patients with n-hexane poisoning have simultaneous damage on motor and sensory nerves, of which sensory nerve damage was more severe. Motor nerves of the lower limbs were severe damaged than those of the upper limbs; whereas injury of sensory nerve in the upper limbs was more severe than that of the lower limbs. After treatment, clinical signs and symptoms of the patients were significantly improved. NCV-EMG result showed a delayed worsening at 3 months then gradually recovered after 12 months. Recovery of the motor nerve was better compared with sensory nerve, with upper limbs faster than that of the lower limbs. PMID:24853719
Inhalation reproductive toxicology studies: Male dominant lethal study of n-hexane in Swiss (CD-1) mice: Final report
Mast, T.J.; Rommereim, R.L.; Evanoff, J.J.; Sasser, L.B.; Decker, J.R.; Stoney, K.H.; Weigel, R.J.; Westerberg, R.B.
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.
Analysis of petroleum contaminated soils by spectral modeling and pure response profile recovery of n-hexane.
Chakraborty, Somsubhra; Weindorf, David C; Li, Bin; Ali, Md Nasim; Majumdar, K; Ray, D P
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)Ā=Ā0.87, RMSEĀ=Ā0.580 log10ĀmgĀkg(-1), and residual prediction deviationĀ=Ā2.78) outperformed all other models tested. Quantitative results obtained by MCR-ALS for n-hexane in presence of interferences (r(2)Ā=Ā0.65 and RMSE 0.261 log10ĀmgĀkg(-1)) were comparable to those obtained using FD (PSR) model. Furthermore, MCR ALS was able to recover pure spectra of n-hexane. PMID:24686115
EXTRACTION OF NEEM OIL (Azadirachta indica A. Juss) USING N-HEXANE AND ETHANOL: STUDIES OF OIL QUALITY, KINETIC AND THERMODYNAMIC
Maria Yuliana Liauw; F. A. Natan; D. Ikasari; N. Indraswati; F. E. Soetaredjo
In this experiment, Neem oil extraction from Neem seeds (Azadirachta indica A. Juss) with n-hexane and ethanol are presented. Effects of particle size, temperature and type of solvent on the extraction kinetic and thermodynamic parameters were studied. Results showed that the maximum oil yields were 41.11% for ethanol and 44.29% for n-hexane at 50 o C, and 0.425-0.71 mm particle
How TOPO affects the interface of the novel mixed water/AOT:TOPO/n-heptane reverse micelles: dynamic light scattering and Fourier transform infrared spectroscopy studies.
Odella, Emmanuel; Falcone, R DarĒo; Silber, Juana J; Correa, N Mariano
In this work we report for the first time the formation of two reverse micelle (RM) media produced by the nonionic surfactant tri-n-octyl phosphine oxide (TOPO) in n-heptane and the one produced by mixing the anionic sodium 1,4-bis-2-ethylhexylsulfosuccinate (AOT) with different TOPO contents dissolved in n-heptane. Dynamic light scattering (DLS) experiments reveal the formation of water/TOPO/n-heptane RMs (TOPO RMs) and water/AOT:TOPO/n-heptane RMs (mixed RMs) since the droplet sizes increase as the water content increases. The addition of TOPO to the system at constant W0 (W0 = [water]/([AOT] + [TOPO])) causes the droplet sizes of mixed RMs to decrease compared with the AOT RMs. In addition, the decrease is larger when the water content is low (W0 = 0.5) but the effect is negligible at the maximum W0 value analyzed (W0 = 2). These results are not expected for mixtures of different nonionic surfactants with AOT and were explained considering the unique TOPO structure. Thus, at W0 = 0.5, we suggest that the percentage of TOPO molecules at the mixed RM interface is higher than those corresponding to the bulk solution. On the other hand, at W0 = 2 the RM interface is comprised mainly of AOT molecules. The FT-IR experiments performed by monitoring monodeuterated water frequency (?(OD)) in TOPO RMs show bound and "bulk-like" water structure even at very low water content. On the other hand, for mixed RMs the water structure depends on the water content. At low W0 value, there are two kinds of water molecules, and at W0 value around 2 only bound water exists. The Fourier transform infrared (FT-IR) experiments performed on the symmetric (?(s)SO3) and asymmetric (?(a)SO3) sulfonate stretching bands of AOT reveal the existence of a strong Na(+)?TOPO complex in the mixed RMs. The results show that adding TOPO to form mixed surfactant RMs with AOT reduces their size, changes the nature of water to have a "bulk-like" character and diminishes the ion pairing of the sulfonate group with Na(+). PMID:24947471
Aggregation behavior of cobalt(II), nickel(II), and copper(II) bis(2-ethylhexyl)phosphate complexes in n-heptane
Yu, Z.J.; Ibrahim, T.H.; Neuman, R.D. [Auburn Univ., AL (United States). Dept. of Chemical Engineering
The solution behavior of divalent transition metal-bis(2-ethylhexyl) phosphate (M(DEHP){sub 2}, M = cobalt, nickel or copper) complexes in n-heptane have been investigated by vapor pressure osmometry, viscometry and dynamic light scattering. The present study provides evidence that divalent transition metal-HDEHP complexes of Ni, Co or Cu can form reversed micelles and shows that molecular modeling can provide new information on the molecular structure of these reversed micellar systems. Improved knowledge of the association microstructure type, structure and composition and of the effect of phase additives on reversed micellar behavior is essential to advance the fundamental understanding of solvent extraction mechanisms.
The absorption spectrum of C60 in n-hexane solution revisited: Fitted experiment and TDDFT/PCM calculations
NASA Astrophysics Data System (ADS)
Menķndez-Proupin, E.; Delgado, Alain; Montero-Alejo, Ana L.; GarcĒa de la Vega, J. M.
The UV absorption spectrum of C60 in n-hexane solvent has been revised by means of numerical analysis and time-dependent density functional theory (TDDFT). The absorption spectrum in the range 3-7 eV has been fitted by a spectral function that includes fourteen transitions with Gaussian lineshape, providing reference transition energies and intensities. The agreement between the experimental and theoretical UV absorption intensities has been considerably improved with respect to previous calculations, by including the solvent dielectric response via the polarizable continuum model (PCM).
Effect of Na+, Mg2+, and Zn2+ chlorides on the structural and thermodynamic properties of water/n-heptane interfaces.
RodrĒguez-Ropero, Francisco; Fioroni, Marco
The effect on the structural and thermodynamic properties in water/n-heptane interfaces on addition of NaCl, MgCl(2), and ZnCl(2) has been examined through five independent 100-ns molecular dynamics simulations. Results indicate that the interfacial thickness within the framework of the capillary-wave model decreases on addition of electrolytes in the order Na(+) < Mg(2+) < Zn(2+), whereas the interfacial tension increases in the same order. Ionic density profiles and self-diffusion coefficients are strongly influenced by the strength of the first hydration shell, which varies in the order Na(+) < Mg(2+) < Zn(2+). On the other hand, the Cl(-) behavior, that is, diffusion and solvation sphere, is influenced by its counterion. Accordingly, cations are strongly expelled from the interface, which is especially remarkable for the small divalent cations. This fact alters the water geometry near the interface and in a lesser extent n-heptane order and number of hydrogen bonds per water molecule close to the interface. PMID:21462228
Solvatochromic behavior of phenol blue in CO2+ethanol and CO2+n-pentane mixtures in the critical region and local composition enhancement.
Chen, Jiawei; Shen, Dong; Wu, Weize; Han, Buxing; Wang, Bo; Sun, Donghai
The UV-Vis spectra of probe phenol blue in CO(2)+ethanol and CO(2)+n-pentane binary mixtures were studied at 308.15 K and different pressures. The experiments were conducted in both supercritical region and subcritical region of the mixtures by changing the compositions of the mixed solvents. On the basis of the experimental results the local compositions of the solvents about phenol blue were estimated by neglecting the size difference of CO(2) and the cosolvents. Then the local composition data were corrected by a method proposed in this work, which is mainly based on Lennard-Jones sphere model. It was demonstrated that the local mole fraction of the cosolvents is higher than that in the bulk solution at all the experimental conditions. In the near critical region of the mixed solvents the local composition enhancement, defined as the ratio of cosolvent mole fraction about the solute to that in the bulk solution, increased significantly as pressure approached the phase boundary from high pressure. The local composition enhancement was not considerable as pressure was much higher than the critical pressure. In addition, in subcritical region the degree of composition enhancement was much smaller and was not sensitive to pressure in the entire pressure range as the concentration of the cosolvents in the mixed solvents was much higher than the concentration at the critical point of the mixtures. PMID:15945753
Reflectometric measurement of n-hexane adsorption on ZnO2 nanohybrid film modified by hydrophobic gold nanoparticles
NASA Astrophysics Data System (ADS)
Seb?k, Dßniel; Csap¾, Edit; ┴brahßm, N¾ra; Dķkßny, Imre
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).
Thermodiffusion, molecular diffusion and Soret coefficient of binary and ternary mixtures of n-hexane, n-dodecane and toluene.
Alonso de Mezquia, David; Wang, Zilin; Lapeira, Estela; Klein, Michael; Wiegand, Simone; Mounir Bou-Ali, M
In this study, the thermodiffusion, molecular diffusion, and Soret coefficients of 12 binary mixtures composed of toluene, n-hexane and n-dodecane in the whole range of concentrations at atmospheric pressure and temperatures of 298.15 K and 308.15 K have been determined. The experimental measurements have been carried out using the Thermogravitational Column, the Sliding Symmetric Tubes and the Thermal Diffusion Forced Rayleigh Scattering techniques. The results obtained using the different techniques show a maximum deviation of 9% for the thermodiffusion coefficient, 8% for the molecular diffusion coefficient and 2% for the Soret coefficient. For the first time we report a decrease of the thermodiffusion coefficient with increasing ratio of the thermal expansion coefficient and viscosity for a binary mixture of an organic ring compound with a short n-alkane. This observation is discussed in terms of interactions between the different components. Additionally, the thermogravitational technique has been used to measure the thermodiffusion coefficients of four ternary mixtures consisting of toluene, n-hexane and n-dodecane at 298.15 K. In order to complete the study, the values obtained for the molecular diffusion coefficient in binary mixtures, and the thermodiffusion coefficient of binary and ternary mixtures have been compared with recently derived correlations. PMID:25376978
ArF excimer laser-induced deposition of Ag/C nanocomposite thin films in the presence of n-Hexane
NASA Astrophysics Data System (ADS)
Gondal, Mohammed Ashraf; Fajgar, Radek; Chang, Xiaofeng; Shen, Kai; Xu, Qingyu
Ag/C nanocomposite thin films with different Ag/C molar ratios have been prepared using ArF excimer laser-induced ablation process and silver target under n-Hexane atmosphere. The morphology, crystal structure and composition of as-deposited Ag/C nanocomposite thin films were investigated with high resolution electronic microscopic techniques (including scanning electron microscopy and transmission electron microscopy) and energy-dispersive X-ray spectroscopy, respectively. Laser Raman spectroscopy and Fourier transform infrared spectroscopy techniques were also applied to characterize the final carbonaceous products generated from n-Hexane under laser ablation process. The optical emission of the plume caused by the interaction between excimer laser and silver target in the presence of n-Hexane was studied to understand the possible reaction process. The UV-vis absorption of as-deposited Ag/C thin films, which is attributed to the surface plasmonic excitation, was also investigated in the present work.
Aromatization of n-hexane by platinum-containing molecular sieves. 1. Catalyst preparation by the vapor phase impregnation method
Suk Bong Hong; Mielczarski, E.; Davis, M.E. (Virginia Polytechnic Inst. and State Univ., Blacksburg, VA (United States))
A vapor phase impregnation method with Pt(acac){sub 2} has been developed and used to load Pt into aluminosilicate (KL, BaKL, NaY, CsNaY, cubic and hexagonal polytypes of faujasite, ZSM-12, and SSZ-24) and aluminophosphate (AlPO{sub 4}-5 and VPI-5) molecular sieves. Pt-containing molecular sieves are characterized by XRD,TPD, elemental analysis, {sup 13}C MAS NMR, TEM, and H{sub 2} chemisorption. {sup 13}C MAS NMR, TEM, and H{sub 2} chemisorption measurements reveal that Pt can be loaded into the micropores of molecular sieves with both charged and neutral frameworks. Pt impregnated into zeolites and aluminophosphates by this method does not migrate to the exterior surface of the molecular sieve catalysts at n-hexane aromatization reaction conditions of atmospheric pressure and temperatures between 460 and 510 C.
Polymorphic conversions of 4- tert-butylcalix[4]arene upon the formation and thermal destruction of a complex with n-hexane
NASA Astrophysics Data System (ADS)
Surov, O. V.; Voronova, M. I.; Smirnov, P. R.; Trostin, V. N.; Mamardashvili, N. Zh.; Zakharov, A. G.
Complex polymorphic conversions of 4- tert-butylcalix[4]arene upon the formation and thermal destruction of a complex with n-hexane were revealed by combined analysis of powder X-ray pictures and data obtained by differential scanning calorimetry.
On the Behavior of Nonionic Surfactants at the N-Heptane/Silica Gel Interface: Influence of the Presence of Interfacial Water Inferred from Adsorption Isotherms and Calorimetric Data.
Lagerge; Keh; Partyka; Lindheimer
The behavior of two polydisperse nonionic surfactants, poly (oxyethylene) glycol alkylphenyl ether TX-35 and TX-100, at the prewetted silica gel/n-heptane and dried silica gel/n-heptane interfaces has been compared by the determination of the average adsorption isotherms of the polydisperse surfactants and of displacement enthalpies. From HPLC experiments, we could also separately quantify the adsorption of each ethyleneoxide (EO) fractions for silica gel from the polydisperse surfactant solution. The adsorption isotherms clearly indicate an incomplete preferential adsorption of the large (EO) chains over the small ones, as well on dried silica gel as on a prehydrated sample. This preferential adsorption and its driving force follow the solubility rules of the poly(oxyethylene) glycol alkylphenyl ether in an apolar solvent and support the idea of a solubility-limited adsorption: solubility in organic solvents of the smaller (EO) chains is much more significant than that of the longer ones and hence prevents adsorption of the smaller species. Consequently, it is observed that the presence of interfacial water decreases the affinity of TX-35 molecules for the hydrophilic silica surface due to the hydration of (EO) chains. In contrast, for TX-100 adsorption after the prewetting treatment the clearest trend is a drastic increase of the adsorption ascribed to the additional solubilization (and micellization) of the TX-100 molecules in the interfacial aqueous phase. The differential molar enthalpies of displacement show a change in the adsorption mechanism, depending on the presence of molecular water on the surface. In the initial part of the adsorption isotherm, a prevailing exothermic process is obtained with prehydrated silica and suggests that hydration of the polar heads of TX-35 and the solubilization of the TX-35 in interfacial water are occurring. For higher equilibrium concentrations, the enthalpies of displacement observed with the prehydrated adsorbent become slightly lower than those obtained with dry silica gel. It may be that this difference is due to the micellization phenomenon of the surfactant species with longer EO chains in interfacial water. These features emphasize the influence of interfacial water on the adsorption of EO fractions from organic solvent. Copyright 2000 Academic Press. PMID:10873328
Modulation of carbon tetrachloride-induced nephrotoxicity in rats by n-hexane extract of Sonchus asper.
Khan, Rahmat Ali; Khan, Muhammad Rashid; Shah, Naseer Ali; Sahreen, Sumaira; Siddiq, Pakiza
Sonchus asper is traditionally used in the treatment of renal dysfunction. In the present study, protective effects of S. asper against carbon tetrachloride (CCl4)-induced nephrotoxicity of rats were determined. In this study, 24 male albino rats (190-200 g) were equally divided into four groups. Group I (control group) was given saline (1 ml/kg body weight (b.w.), 0.85% NaCl) and dimethyl sulfoxide (1 ml/kg b.w.); group II was treated with CCl4 (1 ml/kg b.w. intraperitoneally); groups III and IV were administered with CCl4 and after 48 h with S. asper n-hexane extract (SHE; 100 and 200 mg/kg b.w.). All the treatments were given twice a week for 4 weeks. The results revealed that CCl4-induced oxidative stress as evidenced by the significant depletion of antioxidant enzymes, namely, superoxide dismutase, catalase, peroxidase, glutathione-S-transferase, glutathione peroxidase, glutathione reductase, and glutathione contents, while increased lipid peroxidation (thiobarbituric acid-reactive substances contents). Administration of SHE significantly ameliorated (p < 0.01) the activity of antioxidant enzymes and reduced lipid peroxides. Coadministration revealed that S. asper extract can protect the kidney against CCl4-mediated oxidative damage by restoring the activity of antioxidant enzyme, due to the presence of plant bioactive constituents. PMID:23589407
Auto-ignition of toluene-doped n-heptane and iso-octane/air mixtures: High-pressure shock-tube experiments and kinetics modeling
Hartmann, M.; Fikri, M.; Schulz, C. [Institute for Combustion and Gasdynamics (IVG), University of Duisburg-Essen, Duisburg (Germany); Gushterova, I.; Schiessl, R.; Maas, U. [Institute for Technical Thermodynamics (ITT), Karlsruhe Institute of Technology (KIT), Karlsruhe (Germany)
Toluene is often used as a fluorescent tracer for fuel concentration measurements, but without considering whether it affects the auto-ignition properties of the base fuel. We investigate the auto-ignition of pure toluene and its influence on the auto-ignition of n-heptane and iso-octane/air mixtures under engine-relevant conditions at typical tracer concentrations. Ignition delay times {tau}{sub ign} were measured behind reflected shock waves in mixtures with air at {phi}=1.0 and 0.5 at p=40 bar, over a temperature range of T=700-1200 K and compared to numerical results using two different mechanisms. Based on the models, information is derived about the relative influence of toluene on {tau}{sub ign} on the base fuels as function of temperature. For typical toluene tracer concentrations {<=}10%, the ignition delay time {tau}{sub ign} changes by less than 10% in the relevant pressure and temperature range. (author)
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
Westbrook, C.K.; Warnatz, J.; Pitz, W.J.
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.
Characterization of digestive enzymes from de-oiled mackerel (Scomber japonicus) muscle obtained by supercritical carbon dioxide and n-hexane extraction as a comparative study.
Asaduzzaman, A K M; Chun, Byung-Soo
The oil in mackerel muscle was extracted using an environmental friendly solvent, supercritical carbon dioxide (SC-CO2) at a semi-batch flow extraction process and an n-hexane. The SC-CO2 was carried out at temperature 45Ā░C and pressures ranging from 15 to 25ĀMPa. The flow rate of CO2 (27Āg/min) was constant at the entire extraction period of 2Āh. The highest oil extracted residues after SC-CO2 extraction was used for activity measurement of digestive enzymes. Four digestive enzymes were found in water soluble extracts after n-hexane and SC-CO2 treated samples. Amylase, lipase and trypsin activities were higher in water soluble extracts after SC-CO2 treated samples except protease. Among the four digestive enzymes, the activity of amylase was highest and the value was 44.57ĀuM/min/mg of protein. The water soluble extracts of SC-CO2 and n-hexane treated mackerel samples showed same alkaline optimum pH and pH stability for each of the digestive enzymes. Optimum temperature of amylase, lipase, protease and trypsin was 40, 50, 60 and 30Ā░C, respectively of both extracts. More than 80Ā% temperature stability of amylase, lipase, protease and trypsin were retained at mentioned optimum temperature in water soluble extracts of both treated samples. Based on protein patterns, prominent protein band showed in water soluble extracts after SC-CO2 treated samples indicates no denaturation of protein than untreated and n-hexane. PMID:26028731
Inhalation reproductive toxicology studies: Sperm morphology study of n-hexane in B6C3F1 mice: Final report
Mast, T.J.; Hackett, P.L.; Decker, J.R.; Westerberg, R.B.; Sasser, L.B.; McClanahan, B.J.; Rommereim, R.L.; Evanoff, J.J.
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.
Effect of carriers on physico-chemical properties and activity of Pd nano-catalyst in n-hexane isomerization
NASA Astrophysics Data System (ADS)
Loc Luu, Cam; Thoa Dao, Thi Kim; Nguyen, Tri; Huong Bui, Thanh; Yen Dang, Thi Ngoc; Hoang, Minh Nam; Thoang Ho, Si
In this work zeolites HY, HZSM-5 and mixes of zeolites with ?-Al2O3 in different ratios were taken as carriers for 0.8 wt% Pd catalysts. Physico-chemical characteristics of the catalysts were determined by methods of Brunauer¢Emmett¢Teller (BET)¢N2 adsorption, x-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive x-ray spectroscopy (EDS), transmission electron microscopy (TEM), temperature-programmed reduction (TPR), hydrogen pulse chemisorption (HPC) and NH3 adsorption¢desorption. The activity of catalysts was studied at 225¢450 ░C, at 0.1 and 0.7 MPa with molar ratio of H2:n-C6H14 = 5.92 and n-hexane concentration 9.2 mol%. Mixing of ?-Al2O3 with zeolite made acidity of catalyst weaken and led to a decrease of Pd cluster size, to an increase of Pd dispersity and a reduction of the extent of Pd in the case of catalyst Pd/HY; but for the catalyst Pd/HZSM-5 such mixing led to the reverse effect. That is why the increase of activity in the first case and the decrease of activity in the second case have been observed. It has been found that the optimal ratio of mixed carrier is ?-Al2O3:HY = 2.5:1 and the optimal calcined temperature of NH4ZSM-5 to obtain HZSM-5 is 500¢550 ░C. An increase of reaction pressure from 0.1 to 0.7 MPa remarkably increased the activity, selectivity and stability of Pd-based catalysts.
Antihyperglycemic and antihyperlipidemic effects of n-hexane fraction from the hydro-methanolic extract of sepals of Salmalia malabarica in streptozotocin-induced diabetic rats.
De, Debasis; Ali, Kazi Monjur; Chatterjee, Kausik; Bera, Tushar Kanti; Ghosh, Debidas
Bio-efficacy of n-hexane fraction of sepal of Salmalia malabarica was evaluated covering the biochemical sensors for the management of hyperglycemic and hyperlipidemic effects. Evaluation of n-hexane fraction of Salmalia malabarica (SMH) from hydro-methanolic (2:3) extract at the dose of 0.1 gm/kg body weight twice a day were investigated in normal and streptozotocin (STZ) induced diabetic rats. Normal and STZ-induced diabetic rats were divided into five groups. The effect of the fraction on fasting blood glucose (FBG), serum insulin, hemoglobin, glycated hemoglobin, total cholesterol (TC), triglyceride (TG), high density lipoprotein cholesterol (HDLc), low density lipoprotein cholesterol (LDLc), very low density lipoprotein cholesterol (VLDLc), phospholipids, free fatty acids, urea, uric acid, creatinine, albumin and transaminases were investigated in STZ-induced diabetic rat. A significant reduction of FBG level was observed after SMH treatment in STZ-induced diabetic rat. Treatment of diabetic rats with n-hexane fraction of this plant restored the levels of the above biochemical sensors significantly (p<0.001) in respect to the control. Histological studies of pancreas showed a qualitative diminution in the area of the islet's of Langerhans in diabetic group which was recovered by said fraction. Phytochemical screening of the fraction revealed the presence of flavonoids, terpenoids and steroids. PMID:22732718
Influence of particle size and pH on the removal of trace elements from high-rank coals by n-heptane agglomeration
Martinez-Tarazona, M.R.; Vega, J.M.G.; Garcia, A.B. [CSIC, Oviedo (Spain). Inst. Nacional del Carbon
During combustion and gasification, trace elements are released into the environment, some of them in their vapor phase and others associated with the smaller and more respirable particles. Some of these elements are essential to plant and animal life, while others by be toxic under certain conditions and concentration. Although the effect of trace element emissions is not well known, and the evaluation of the potential toxicity of each element and its common compounds is an issue to be clarified, the growing concerns over environmental aspects associated with trace elements had led to the introduction in many countries of regulations on their emissions form coal fired power plants. The removal of trace elements from coal as a preliminary to coal utilization will be necessary in order to comply with stricter future environmental laws. Physical cleaning techniques, which rely on differences in density or surface properties between organic and inorganic components of coals, are able to reduce content of trace elements associated with mineral matter liberated during grinding. Provided that most trace elements in coal are associated with minerals which are finely disseminated in the coal matrix, advanced physical cleaning processes which are efficient for very small particle sizes, such as oil agglomeration, should be used for separating these elements from coal. In the work described below two Spanish anthracites were agglomerated with n-heptane, over a wide pH range, and the removal of several major and trace elements from these coals during the process evaluated. The influence of pH and coal particle size on the elimination of trace elements from these coals by agglomeration has been investigated.
Dynamic hydrocarbon separation in high-temperature, high-pressure, liquid n-alkane water vapor systems by steam distillationĀ
Vlierboom, Casper-Maarten
32 Rate of 4. 00 cc/min. , 345 'F and 126 psia 33 14. Effect of Rate on a n-Hexane, n-Heptane, n-Octane Ternary System at Saturated Steam Conditions of 345 'F and 126 psia 35 15. Comparison of Multi-component Yield to Pure n-Heptane Yield at 2...-Hexane Distribution for a n-Hexane- n-Heptane - n-Octane Ternary Mixture at Saturated Steam Conditions of 345 0F and 126 psia 77 42. Rate Effect on the n-Heptane Distribution for a n-Hexane- n-Heptane ? n-Octane Ternary Mixture at Saturated Steam Conditions...
Steam reforming of n-hexane on pellet and monolithic catalyst beds. A comparative study on improvements due to heat transfer
NASA Astrophysics Data System (ADS)
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.
Cytogenetic analysis of buccal cells from shoe-workers and pathology and anatomy laboratory workers exposed to n-hexane, toluene, methyl ethyl ketone and formaldehyde.
Burgaz, Sema; Erdem, Onur; Cakmak, Gonca; Erdem, Nurten; Karakaya, Asuman; Karakaya, Ali Esat
People employed in the shoe manufacture and repair industry are at an increased risk for cancer, the strongest evidence being for nasal cancer and leukaemia. A possible causal role for formaldehyde is likely for cancer of the buccal cavity and nasopharynx. Exfoliated buccal cells are good source of tissue for monitoring human exposure to inhaled and ingested occupational and environmental genotoxicants. To assess the cytogenetic damage related to occupational exposure to airborne chemicals during shoe-making and the processes in pathology and anatomy laboratories, the micronuclei (MN) count per 3000 cells was measured in buccal smears from shoe-workers (group I, n = 22) exposed to mainly n-hexane, toluene and methyl ethyl ketone (MEK) and from anatomy and pathology staff (group II, n = 28) exposed to formaldehyde (FA). Eighteen male university staff were used as controls. The mean time-weighted average (TWA) concentrations of n-hexane, toluene and MEK in 10 small shoe workshops were 58.07 p.p.m., 26.62 p.p.m. and 11.39 p.p.m., respectively. The measured air concentrations of FA in the breathing zone of the anatomy and pathology laboratory workers were between 2 and 4 p.p.m. Levels of 2,5-hexadione (2,5-HD) and hippuric acid (HA), metabolic markers of n-hexane and toluene exposure, respectively, were significantly higher in the urine of workers in group I than in control subjects (p < 0.001 and p < 0.01, respectively). The mean (+/- SD) MN (0/00) [corrected] frequencies in buccal mucosa cells from workers in group I, group II and controls were 0.62 +/- 0.45%, 0.71 +/- 0.56% and 0.33 +/- 0.30%, respectively (p < 0.05 and p < 0.05 compared with controls for group I and group II, respectively). The effects of smoking, age and duration of exposure on the frequency of micronucleated buccal cells from workers in all three groups studied were also evaluated. Overall, the results suggest that occupational exposure to organic solvents, mainly n-hexane, toluene, MEK and FA, may cause cytogenetic damage in buccal cells and that use of exfoliated buccal cells seems to be appropriate to measure exposure to organic solvents. PMID:12101634
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)
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.
Aromatization of n-heptane over H-AlMFI, Ga\\/H-AlMFI, H-GaMFI and H-GaAlMFI zeolite catalysts: influence of zeolitic acidity and non-framework gallium
V. R Choudhary; S. A. R Mulla; S Banerjee
Influence of zeolite acidity (strong acid sites measured in terms of the pyridine chemisorbed at 400 ░C) and non-framework Ga-species present in the zeolite channels on the conversion (total and to aromatics) and selectivity in the aromatization of n-heptane at 500 ░C over the H-AlMFI (H-ZSM-5), Ga\\/ H-AlMFI, H-GaMFI and H-GaAlMFI zeolite catalysts (GHSV=3400 and 13,600 h?1) has been investigated.
Dilution method study on the interfacial composition and structural parameters of water\\/C 12¢ EO x ¢C 12?2Br\\/ n-hexanol\\/ n-heptane microemulsions: Effect of the oxyethylene groups in the spacer
Ou Zheng; Jian-Xi Zhao; Hua Yan; Shao-Kang Gao
The interfacial composition and the structure of the water\\/C12¢EOx¢C12?2Br\\/n-hexanol\\/n-heptane microemulsion have been investigated by the dilution method. The results showed that C12¢EOx¢C12?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 C12¢2¢C12?2Br system. The radius of the
A molecular dynamics investigation of the unusual concentration dependencies of Fick diffusivities in silica mesopores
Krishna, Rajamani; van Baten, Jasper M
Molecular Dynamics (MD) simulations were carried out to determine the self-diffusivitiy, D{sub i,self}, the Maxwell¢Stefan diffusivity, ą{sub i}, and the Fick diffusivity, D{sub i}, for methane (C1), ethane (C2), propane (C3), n-butane (nC4), n-pentane (nC5), n-hexane (nC6), n-heptane (nC7), and cyclohexane (cC6) in cylindrical silica mesopores for a range of pore concentrations. The MD simulations show that zero-loading diffusivity ą{sub i}(0) is consistently lower, by up to a factor of 20, than the values anticipated by the classical Knudsen formula. The concentration dependence of the Fick diffusivity, D{sub i} is found to be unusually complex, and displays a strong minimum in some cases; this characteristic can be traced to molecular clustering.
Optimization of an automated FI-FT-IR procedure for the determination of o-xylene, toluene and ethyl benzene in n-hexane
Wells, Ian; Worsfold, Paul J.
The development and optimization of an automated flow injection (FI) manifold coupled with a Fourier transform infrared (FT-IR) detector for the determination of toluene, ethyl benzene and o-xylene in an n-hexane matrix is described. FT-IR parameters optimized were resolution and number of co-added scans; FI parameters optimized were type of pump tubing, carrier flow rate and sample volume. ATR and transmission flow cells were compared for the determination of o-xylene, the ATR cell was easier to use and gave better figures of merit, except for sensitivity, for which the transmission cell was twice as good. Multivariate calibration routines were applied to the FI-FT-IR data and the PLS1 algorithm gave relative root mean standard errors of crossvalidation (RRMSECVs) < 7% for all three analytes using mean-centred data and the first derivative for o-xylene. PMID:18924847
Determination of vapor liquid equilibrium for the ternary iso-propanol/atactic-polypropylene/n-heptane mixture at 105C and 140C, and the binary iso-propanol/atactic-polypropylene mixture at 85C using perturbation gas chromatography / cby Lamar Lane Joffrion
Joffrion, Lamar Lane
to Bondi's recommendation (1964). Using Bondi's work s;/sf is 1. 13 for the IPA/APP mixture and 1. 06 for the n-heptane/APP mixture. In Figure 6, composition isotherms are shown for the IPA/APP mixture using interpolation and integration results...
Liquid-liquid equilibria for ternary systems containing hydrocarbons and propylene carbonate
Annesini, M.C.; Gironi, F.; Marrelli, L.
Experimental data of liquid-liquid equillibrium at 20/sup 0/C are reported for six ternary systems containing propylene carbonate with n-hexane-benzene, n-hexane-ethylbenzene, n-heptane-toluene, n-heptane-ethylbenzene, n-octane-o-xylene, and n-octane-ethylbenzene. The data are correlated by means of NRTL and UNIQUAC models and relative parameters are given.
Transport properties of nonelectrolyte liquid mixtures---II. Viscosity coefficients for the n-hexane + n-hexadecane system at temperatures from 25 to 100ćC at pressures up to the freezing pressure or 500 MPa
J. H. Dymond; K. J. Young; J. D. Isdale
Viscosity coefficients measured with an estimated accuracy of 2% using a self-centering falling body viscometer are reported for n-hexane, n-hexadecane, and four binary mixtures at 25, 50, 75, and 100ćC at pressures up to the freezing pressure or 500 MPa. The data for a given composition at different temperatures and pressures are very satisfactorily correlated by a plot of ?,
Transport properties of nonelectrolyte liquid mixturesŚII. Viscosity coefficients for the n-hexane + n-hexadecane system at temperatures from 25 to 100ćC at pressures up to the freezing pressure or 500 MPa
J. H. Dymond; K. J. Young; J. D. Isdale
Viscosity coefficients measured with an estimated accuracy of 2% using a self-centering falling body viscometer are reported for n-hexane, n-hexadecane, and four binary mixtures at 25, 50, 75, and 100ćC at pressures up to the freezing pressure or 500 MPa. The data for a given composition at different temperatures and pressures are very satisfactorily correlated by a plot of ?,
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.
Zheng, Ou; Zhao, Jian-Xi; Yan, Hua; Gao, Shao-Kang
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
Rate Constants for the Reactions of Hydroxyl Radical with Several Alkanes, Cycloalkanes, and Dimethyl Ether
NASA Technical Reports Server (NTRS)
DeMore, W.; Bayes, K.
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.
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...
A comparison of the reactivity of {open_quotes}nonequilibrated{close_quotes} and {open_quotes}equilibrated{close_quotes} V-P-O catalysts: Structural evolution, surface characterization, and reactivity in the selective oxidation of n-butane and n-pentane
Albonetti, S.; Cavani, F.; Trifiro, F.; Venturoli, P. [Industriale e dei Materiali, Viale Risorgimento, Bologna (Italy)] [and others] [Industriale e dei Materiali, Viale Risorgimento, Bologna (Italy); and others
Structural alteration as a result of thermal treatment of VOHPO{sub 4}{center_dot}4H{sub 2}O was studied. Calcination induces partial oxidization, resulting in a phase composed of an amorphous V{sup IV}-P mixed oxide and a crystalline hydrated V{sup V}-P-O phase. When left in a 1% hydrocarbon/air stream for 100 h leads to a{open_quotes}nonequilibrated{close_quotes} catalyst, and after 1000 h to the {open_quotes}equilibrated{close_quotes} catalyst. Catalytic activity of the nonequilibrated and equilibrated catalysts in n-butane and n-pentane oxidation was studied. The catalysts were structurally characterized by XRD, FT-IR, chemical analysis. TGA, XPS, and TPD. The equilibrated catalyst consisted of well crystallized (VO){sub 2}P{sub 2}O{sub 7} with homogeneously distributed surface sites. The nonequilibrated catalyst displayed mixed phases and nonhomogeneous surface sites. 38 refs., 18 figs., 2 tabs.
Determination of thermodynamic properties of poly (cyclohexyl methacrylate) by inverse gas chromatography.
Kaya, Ismet; Pala, Cigdem Yigit
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
Catalytic activity of bulk tungsten carbides for alkane reforming. II. Catalytic activity of tungsten carbides modified by oxygen
Keller, V.; Wehrer, P.; Garin, F. [CNRS, Strasbourg (France)] [and others] [CNRS, Strasbourg (France); and others
The influence of oxygen on the reforming activity of bulk tungsten carbide (WC) has been studied for the reaction of pentanes, hexanes, heptanes, and two olefins (2-methyl-2-pentene and 4-methyl-1-pentene). Depending on the air treatment, at low (-78{degrees}C), moderate (350{degrees}C), or high (700{degrees}C) temperature, these alkanes lead to different reaction products as a result of different reaction mechanisms. Whatever the oxygen treatment, heptanes react faster than hexanes, which are more reactive than pentanes. Furthermore, cyclanes (methylcyclopentane or ethylcyclopentane) are less reactive than linear alkanes (n-pentane, n-hexane, or n-heptane), which react more slowly than the branched ones (isopentane, 2-methylpentane, 3-methylhexane). Whatever the oxygen treatment, no cyclic mechanism is involved and isomerization proceeds only through two kinds of bond-shift mechanisms. In order to obtain more information about the possible mechanisms, i.e., a bifunctional mechanism with dehydrogenation/hydrogenation on metallic sites and carbenium ion rearrangement on acidic sites, two unsaturated reactants (2-methyl-2-pentrene and 4-methyl-1-pentene) have been tested. The reaction mechanisms and a kinetic model are discussed in detail in a forthcoming paper. 14 refs., 8 figs., 9 tabs.
Transport properties of nonelectrolyte liquid mixtures---III. Viscosity coefficients for n-octane, n-dodecane, and equimolar mixtures of n-octane + n-dodecane and n-hexane + n-dodecane from 25 to 100░C at pressures up to the freezing pressure or 500 MPa
J. H. Dymond; J. Robertson; J. D. Isdale
Viscosity coefficients measured with an estimated accuracy of 2% using a new design of self-centering falling body viscometer are reported for n-octane, n-dodecane, and equimolar mixtures of n-octane + n-dodecane and n-hexane + n-dodecane at 25, 50, 75, and 100░C at pressures up to the freezing pressure or 500 MPa. The data for a given composition at different temperatures and
Transport properties of nonelectrolyte liquid mixturesŚIII. Viscosity coefficients for n -octane, n -dodecane, and equimolar mixtures of n -octane + n -dodecane and n -hexane + n -dodecane from 25 to 100░C at pressures up to the freezing pressure or 500 MPa
J. H. Dymond; J. Robertson; J. D. Isdale
Viscosity coefficients measured with an estimated accuracy of 2% using a new design of self-centering falling body viscometer are reported for n-octane, n-dodecane, and equimolar mixtures of n-octane + n-dodecane and n-hexane + n-dodecane at 25, 50, 75, and 100░C at pressures up to the freezing pressure or 500 MPa. The data for a given composition at different temperatures and
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
NASA Astrophysics Data System (ADS)
Abdelsayed, Victor; Samy El-Shall, M.
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.
Technology Development for Iron and Cobalt Fischer-Tropsch Catalysts Quarterly Report
Kentucky, University of
and effective in maintaining a steady inventory of catalyst slurry in contact with the gas-phase. Measured activation, the catalyst particle mean diameter decreased in an exponential decay fashion. Attrition effects a pressure/density tuned supercritical fluid mixture of n-pentane/n- hexane. By using an inert gas
Modeling of NO sensitization of IC engines surrogate fuels auto-ignition and combustion
J÷rg Anderlohr; A. Pires Da Cruz; Roda Bounaceur; Frķdķrique Battin-Leclerc
This paper presents a new chemical kinetic model developed for the simulation of auto-ignition and combustion of engine surrogate fuel mixtures sensitized by the presence of NOx. The chemical mechanism is based on the PRF auto-ignition model (n-heptane\\/iso-octane) of Buda et al. [1] and the NO\\/n-butane\\/n-pentane model of Glaude et al. [2]. The later mechanism has been taken as a
Modeling of NO sensitization of IC engines surrogate fuels auto-ignition and combustion
J÷rg Anderlohr; A. Pires Da Cruz; Roda Bounaceur; F. Battin Leclerc
This paper presents a new chemical kinetic model developed for the simulation\\u000aof auto-ignition and combustion of engine surrogate fuel mixtures sensitized by\\u000athe presence of NOx. The chemical mechanism is based on the PRF auto-ignition\\u000amodel (n-heptane\\/iso-octane) of Buda et al. [1] and the NO\\/n-butane\\/n-pentane\\u000amodel of Glaude et al. [2]. The later mechanism has been taken as a
An atmospheric pressure chemical ionization study of the positive and negative ion chemistry of the hydrofluorocarbons 1,1-difluoroethane (HFC-152a) and 1,1,1,2-tetrafluoroethane (HFC-134a) and of perfluoro-n-hexane (FC-72) in air plasma at atmospheric pressure.
Marotta, Ester; Paradisi, Cristina; Scorrano, Gianfranco
A report is given on the ionization/dissociation behavior of the title compounds within air plasmas produced by electrical corona discharges at atmospheric pressure: both positive and negative ions were investigated at different temperatures using atmospheric pressure chemical ionization mass spectrometry (APCI-MS). CHF(2)CH(3) (HFC-152a) undergoes efficient ionic oxidation to C(2)H(5)O(+), in which the oxygen comes from water present in the plasma. In contrast, CF(3)CH(2)F (HFC-134a) does not produce any characteristic positive ion under APCI conditions, its presence within the plasma being revealed only as a neutral ligand in ion-molecule complexes with ions of the background (H(3)O(+) and NO(+)). Analogously, the perfluorocarbon FC-72 (n-C(6)F(14)) does not produce significant positive ions at 30 degrees C: at high temperature, however, it undergoes dissociative ionization to form many product ions including C(3)F(6)(+), C(2)F(4)(+), C(n)F(2n+1)(+) and a few families of oxygen containing cations (C(n)F(2n+1)OH(2)(+), C(n)F(2n)OH(+), C(n)F(2n-1)O(+), C(n)F(2n-1)O(2)H(2)(+), C(n)F(2n-2)O(2)H(+)) which are suggested to derive from C(n)F(2n+1)(+) in a cascade of steps initiated by condensation with water followed by steps of HF elimination and H(2)O addition. Negative ions formed from the fluoroethanes CHF(2)CH(3) and CF(3)CH(2)F (M) include complexes with ions of the background, O(2)(-)(M), O(3)(-)(M) and some higher complexes involving also water, and complexes of the fluoride ion, F(-)(H(2)O), F(-)(M) and higher complexes with both M and H(2)O also together. The interesting product O(2)(-)(HF) is also formed from 1,1-difluoroethane. In contrast to the HFCs, perfluoro-n-hexane gives stable molecular anions, M(-), which at low source temperature or in humidified air are also detected as hydrates, M(-)(H(2)O). In addition, in humidified air F(-)(H(2)O)(n) complexes are also formed. The reactions leading to all major positive and negative product ions are discussed also with reference to available thermochemical data and relevant literature reports. The effects on both positive and negative APCI spectra due to ion activation via increasing V(cone) are also reported and discussed: several interesting endothermic processes are observed under these conditions. The results provide important information on the role of ionic reactions in non-thermal plasma processes. PMID:15282758
High-pressure viscosity and density of n -alkanes
E. Kiran; Y. L. Sen
High-pressure viscosities and densities of n-butane, n-pentane, n-hexane, and n-octane have been measured with a specially designed falling cylinder viscometer. Data cover the pressure range from 10 to 70 MPa at temperatures from 310 to 450 K. When the viscosity is plotted as a function of density, the data at all temperatures and pressures are shown to reduce to a
Natural and synthetic oviposition stimulants for Catolaccus grandis (Burks) females
Antonio A. Guerra; Susana Martinez; Hilda Sonia Del Rio
Oviposition behavior was elicited fromCatolaccus grandis (Burks) (Hymenoptera: Pteromalidae) females, an ectoparasitoid of the boll weevil,Anthonomus grandis Boheman (Coleoptera: Curculionidae), by smears of freshly cut cotton bolls or smears of extracts prepared with boll weevil damaged or undamaged cotton boll tissues. Oviposition behavior was also elicited fromC. grandis females by smears made withn-pentane,n-hexane,n-heptane, and isooctane. This is the first report
A local composition model for the prediction of mutual diffusion coefficients in binary liquid mixtures from tracer diffusion coefficients
Zhu, Qingyu; Moggridge, Geoff D.; DÆAgostino, Carmine
. However, in general, it is more correct to state that the diffusion flux originates from the deviation from equilibrium between molecular friction and thermodynamic interactions (Taylor and Krishna, 1993). Thus, from a thermodynamic perspective... and frictional coefficients for the systems benzene¢chlorobenzene, benzene¢n-hexane and benzene n-heptane at 25 oC. J. Phys. Chem 74 (19), 3518¢3529. Hartley, G.S., J. Crank, J., 1949. Some fundamental definitions and concepts in diffusion processes. Trans...
Hydroisomerization and hydrocracking of n-heptane and n-hexadecane on solid superacids
M. Y. Wen; I. Wender; J. W. Tierney
Formation of highly branched long-chain paraffins and highly isomerized shorter chain paraffins from conversion of heavier n-paraffinic fractions is of interest for the production of high-octane gasoline, jet fuel, and lubricants. In this study, n-hexadecane was hydroisomerized and hydrocracked on a platinum-doped solid superacid, Pt\\/ZrOŌ\\/SOŌ┬▓Ōü╗, in a batch horizontal shaking microreactor system at rather mild conditions: 130-170┬░C, 300 psig initial
Spin-lattice relaxation of the quinoxaline triplet state in n-alkane matrices measured in zero magnetic field
NASA Astrophysics Data System (ADS)
Ghosh, Sanjib; Petrin, Michael; Maki, August H.
The individual spin-lattice relaxation (SLR) rate constants (Wij) between the sublevels of the lowest triplet state of quinoxaline in n-pentane and in n-hexane Sphol'skii hosts over the temperature range of 1.2 to 4.2 K have been measured in zero applied magnetic field. The anisotropy pattern for the Wij for quinoxaline in these n-alkane hosts differs from that observed in a durene host. In durene, the SLR rate constant between the two in-plane sublevels was found to be dominant, and was suggested to occur via an Orbach relaxation process involving a localized phonon state with rotated spin axes. It is proposed here that the dominant relaxation route between the short in-plane axis sublevel (Ty) and the out-of-plane axis sublevel (Tx) observed for quinoxaline in n-alkane hosts is the result of a spin-orbit-phonon coupling. In the temperature range of 2.5 to 4.2 K, the SLR rate constant Wyx exhibits Raman relaxation with a T7 temperature dependence in an n-pentane host. In n-hexane, where the relaxation is much faster than that in n-pentane, the mechanism observed appears to be a combination of a normal direct process and a Raman process in the temperature range of 1.2 to 3.2 K. Individual decay constants for the triplet sublevels in the temperature range investigated are also presented.
The Effective Diffusivity of Cyclopentane and n-Pentane in PU and PUIR Foams by Thin-Slice Gravimetric Analysis
J. Richard Booth; Deb Bhattacharjee
Monitoring thermal conductivity changes in thin-sliced cellular plastics has drastically reduced the time required to evaluate the long-term aging of insulating foams. Monitoring the weight changes of closed-cell thin-slices provides data which can be analyzed to determine the effective diffusivity of atmospheric and blowing agent gas components. The effective diffusivity of atmospheric gases are about two orders of magnitude larger
A study of PVT relations for carbon dioxide, n-pentane, and n-octane mixtures using a recombination apparatus
Wirawan, Januar Fitri Santo
0. 00 000. 00 724. 00 703. 10 01e. so 013 00 DSS OD 1925. 00 1421 00 15'lr SD 1610 SD 1094 00 1703 00 180000 I $21. 00 1 795. 00 1 71 7. 00 1704. 00 1890. 00 1675. 00 0. 00 8. 25 0. 34 12. 00 '13 50 20. 14 20 70 27AI 20...
Aerobic/anaerobic/aerobic sequenced biodegradation of a mixture of chlorinated ethenes, ethanes and methanes in batch bioreactors.
Frascari, Dario; Fraraccio, Serena; Nocentini, Massimo; Pinelli, Davide
A novel aerobic/anaerobic/aerobic treatment was implemented in batch reactors containing aquifer materials from a site contaminated by tetrachloroethylene (PCE), trichloroethylene (TCE), vinyl chloride (VC), 1,1,2-trichloroethane (1,1,2-TCA) and chloroform (CF). Consortia grown aerobically on methane, propane, n-pentane and n-hexane completely biodegraded the chlorinated solvent mixture, via aerobic cometabolism of VC, CF, TCE and 1,1,2-TCA, followed by PCE reductive dechlorination (RD) to 1,2-cis-dichlorothylene (cis-DCE) or TCE, and cis-DCE/TCE cometabolism in a further aerobic phase. n-Hexane was the best substrate. No electron donor was supplied for RD, which likely utilized cellular material produced during the aerobic phase. Chloride release was stoichiometric with chlorinated solvent biodegradation. According to the Lepidium sativum ecotoxicity test, a decreased toxicity was observed with propane, n-pentane and n-hexane, but not methane. A kinetic study of PCE RD allowed to estimate the PCE maximum specific rate (0.57 ▒ 0.07 mg mg(protein)(-1) day(-1)) and half-saturation constant (6.7 ▒ 1.5 mg L(-1)). PMID:23201903
Nanosized Platinum-Loaded H-ZSM-5 Zeolite Catalysts for n-Hexane Hydroconversion
A. K. Aboul-Gheit; S. M. Abdel-Hamid; D. S. El-Desouki
A series of nanosized platinum-containing catalysts was successfully loaded on\\/in zeolite H-ZSM-5 via exchanging the zeolitic proton with platinum from Pt tetramine dichloride complex. Another series of Pt\\/H-ZSM-5 catalysts was prepared via wet impregnation of H2PtCl6 solution for comparison. The latter series was found to produce lower Pt dispersion. Pt dispersion was determined by H2 chemisorption. Catalyst characterization via ammonia
Batch polymerization of isoprene in n-hexane by n-butyllithium initiation
Porter, Raymond Eugene
33 percent of the initial amount of n-butyl- lithium had reacted at a point where 70 percent of the original isoprene was polymerized. Morton et al. (1963b) also verified, by comparing kinetic and viscometric mole- cular weights of polyisoprene.... The kinetics of propagation of polyisoprenyllithium have been investigated by many (Sinn et al. , 1964a, 1964b; Morton et al. , 1963a, 1963c; Spirin et al. , 1962; Worsfold and Bywater, 1964; Hsieh, 1965; Margerison et al. , 1968). Most of the workers...
Batch polymerization of isoprene in n-hexane by n-butyllithium initiationĀ
Porter, Raymond Eugene
of the polymer to be in excess of 90 percent cis-1, 4 content, making it very similar to natural hevea rubber. O'Driscoll and Tobolsky (1959) found that for styrene polymerized in benzene with n-butyllithium as an initiator, the maximum rate of polymerization... ) (39) P 1 j 1 j k (C + ~ ~ ~ + C ) = a(P + ~ ~ ~ + P ) p 1 z 1 z (4o) and subtracting equation (38) from (39), leads to 24 1& C = GP P (41) Edgar (1970) has shown that the material balance equation for the propagation reaction may be written...
n-Hexane-induced changes in nerve conduction velocities and somatosensory evoked potentials
A. Mutti; F. Ferri; G. Lommi; S. Lotta; S. Lucertini; I. Franchini
Fifteen women from a shoe factory were examined clinically and their cerebral evoked responses to 256 electrical stimulations of the median nerve were averaged. Neurophysiological investigations included maximal motor (MCV) and distal sensory (dSCV) nerve conduction velocity measurement on ulnar, median, and peroneal nerves. A referent group was composed of 15 age-matched women without exposure to neurotoxic chemicals. MCVs and
Lipase-catalyzed synthesis of terpene esters by transesterification in n-hexane
Paul A. Claon; Casimir C. Akoh
Short chain fatty acid esters of geraniol and citronellol were synthesized by lipase-catalyzĶd transesterification with yields as high as 98% molar conversion. Triacylglycerols were the best substrates and immobilized Candida antarctica lipase, SP435 gave the highest overall yields. The lipases tested successfully accommodated novel acyl donors such as isopropenyl acetate and glycidyl butyrate.
Fischer-Tropsch synthesis in the slurry phase on iron catalystsĀ
Brown, Russell Floyd
conductivity 40 minutes '0 O 0 0 0 o 2 0 '0 Ll 9 2 H 8. A o g Q Ni Valve Snitch Propane Propylene Iso-butane N-Butane I-Butane Isobutylene ~ Trans-2-butane Ctg-2-butane Valve Suicch Ethylene Ethane Valve Snitch 0 2 N CH... Propylene Propane 1-Butene n-Butane 1-Pentene n-Pentane 1-Hexene n-Hexane CO+CHg C02 Start Air Ocl 0 I CI '0 O 0 I 0 9 I 0 P 0 0 0 'a I '0 0 Q. 0 ttethanol Acetaldehyde C& Aldehyde/Ketone 1-Propanol Ethanol Water 1-Butanol...
Sooting behaviour of n-heptane laminar diffusion flames at high Ahmet E. Karatas, Gorngrit Intasopa, mer L. Glder
G³lder, ųmer L.
Reconstruction et pr┤ediction d'┤etats de mer `a l'aide d'observations spatio-temporelles de la surface libre de la mer `a partir d'observations spatio-temporelle discr`etes de celle- ci au moyen d vagues qui auront ┤et┤e correctement reconstruites par l'algorithme. Cependant, pour des ┤etats de mer
(Liquid + liquid) equilibria in the binary systems (aliphatic, or aromatic hydrocarbons + 1-ethyl-3-methylimidazolium ethylsulfate, or 1-butyl-3-methylimidazolium methylsulfate ionic liquids)
Julißn GarcĒa; Josķ S. Torrecilla; Adela Fernßndez; Mercedes Oliet; Francisco RodrĒguez
(Liquid+liquid) equilibria of 14 binary systems composed of n-hexane, n-heptane, benzene, toluene, o-xylene, m-xylene, or p-xylene and 1-ethyl-3-methylimidazolium ethylsulfate, [emim]EtSO4, or 1-butyl-3-methylimidazolium methylsulfate, [bmim]MeSO4, ionic liquids have been done in the temperature range from (293.2 to 333.2)K. The solubility of aliphatic is less than those of the aromatic hydrocarbons. In particular, the solubility of hydrocarbons in both ionic liquids increases
Thermodynamics of mixing C/sub 6/ and C/sub 7/ compounds with a bicyclic compound at infinite dilution
Letcher, T.M.; Baxter, R.
The activity coefficients at infinite dilution have been measure at 25/sup 0/C for cyclohexane, cyclohexene, 1,3-cyclohexadiene, 1,4-cyclohexadiene, benzene, n-hexane, 1-hexene, 1-hexyne, n-heptane, 1-heptene and 1-heptyne in decahydronaphthalene, bicyclohexyl, 1,2,3,4-tetrahydronaphthalene and cyclohexylbenzene. These results, together with previously determined H/sup E//sub m/ and V/sup E//sub m/ have been used to calculate the partial molar excess thermodynamic properties of mixing at infinite dilution.
Fuel property effects on engine combustion processes. Final report
Cernansky, N.P.; Miller, D.L.
A major obstacle to improving spark ignition engine efficiency is the limitations on compression ratio imposed by tendency of hydrocarbon fuels to knock (autoignite). A research program investigated the knock problem in spark ignition engines. Objective was to understand low and intermediate temperature chemistry of combustion processes relevant to autoignition and knock and to determine fuel property effects. Experiments were conducted in an optically and physically accessible research engine, static reactor, and an atmospheric pressure flow reactor (APFR). Chemical kinetic models were developed for prediction of species evolution and autoignition behavior. The work provided insight into low and intermediate temperature chemistry prior to autoignition of n-butane, iso-butane, n-pentane, 1-pentene, n-heptane, iso-octane and some binary blends. Study of effects of ethers (MTBE, ETBE, TAME and DIPE ) and alcohols (methanol and ethanol) on the oxidation and autoignition of primary reference fuel (PRF) blends.
High pressure combustion of liquid fuels. [alcohol and n-paraffin fuels
NASA Technical Reports Server (NTRS)
Canada, G. S.
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.
Modeling of NO sensitization of IC engines surrogate fuels auto-ignition and combustion
Anderlohr, J÷rg; Bounaceur, Roda; Battin-Leclerc, Frķdķrique
This paper presents a new chemical kinetic model developed for the simulation of auto-ignition and combustion of engine surrogate fuel mixtures sensitized by the presence of NOx. The chemical mechanism is based on the PRF auto-ignition model (n-heptane/iso-octane) of Buda et al. [1] and the NO/n-butane/n-pentane model of Glaude et al. [2]. The later mechanism has been taken as a reference for the reactions of NOx with larger alcanes (n-heptane, iso-octane). A coherent two components engine fuel surrogate mechanism has been generated which accounts for the influence of NOx on auto-ignition. The mechanism has been validated for temperatures between 700 K and 1100 K and pressures between 1 and 10 atm covering the temperature and pressure ranges characteristic of engine post-oxidation thermodynamic conditions. Experiments used for validation include jet stirred reactor conditions for species evolution as a function of temperature, as well as diesel HCCI engine experiments for auto-ignition delay time measurements...
Catalytic activity of pentasil type zeolites with different structures of the channels, in n-Hexane conversion
Rosolovskaya, E.N.; Barsukov, O.V.; Meged', N.F.; Trunova, V.I.
Hydrothermal synthesis using tetrabutylammonium (TBA) and monoethanolamine (MEA) has been applied to the synthesis of high-silica zeolites of the pentasil type, both with the same content of aluminum in the elementary cell and with identical dimensions of the crystals. The zeolites had the same catalytic activity in the overall conversion of hexane, but differed in selectivity. The zeolite obtained with TBA gave reaction products with higher contents of aromatic hydrocarbons and lower contents of C/sub 1/-C/sub 4/ light hydrocarbons. The differences in selectivity are explained by differences in the geometry of the zeolite channels.
Catalytic activity of pentasil type zeolites with different structures of the channels, in n-Hexane conversion
E. N. Rosolovskaya; O. V. Barsukov; N. F. Meged; V. I. Trunova
Hydrothermal synthesis using tetrabutylammonium (TBA) and monoethanolamine (MEA) has been applied to the synthesis of high-silica zeolites of the pentasil type, both with the same content of aluminum in the elementary cell and with identical dimensions of the crystals. The zeolites had the same catalytic activity in the overall conversion of hexane, but differed in selectivity. The zeolite obtained with
Iridium Clusters in KLTL Zeolite: Synthesis, Structural Characterization, and Catalysis of Toluene Hydrogenation and n-Hexane Dehydrocyclization
Ailian Zhao; R. E. Jentoft; B. C. Gates
Iridium clusters incorporating about six atoms each, on average, were prepared in KLTL zeolite by decarbonylation (in H2at 400░C) of iridium carbonyl clusters formed by treatment of adsorbed [Ir(CO)2(acac)] in CO at 1 atm and 175░C. The supported species were characterized by infrared and extended X-ray absorption fine structure (EXAFS) spectroscopies. The iridium carbonyls formed from [Ir(CO)2(acac)] were predominantly [HIr4(CO)11]?with
Dynamics of pyrenesemicarbazide and pyrenethiosemicarbazide in reverse micelle of AOT in n-heptane: Probing critical penetration of water molecules toward the palisade
NASA Astrophysics Data System (ADS)
Maity, Arnab; Das, Shrabanti; Ghosh, Prasun; Das, Tarasankar; Seth, Sourav Kanti; Mondal, Somen; Gupta, Parna; Purkayastha, Pradipta
In the present work, we have introduced two similar probe molecules with pyrene tags that can reside in different positions in the reverse micelles and show opposite dynamism on excitation. Herein, we have changed the concentration of water in the reverse micellar core gradually and monitored the spectrochemical changes in the dynamism of the two designed probe molecules. The results indicate that water molecules penetrate through the interface of the reverse micelles up a certain critical amount.
CONDENSED MATTER: ELECTRONIC STRUCTURE, ELECTRICAL, MAGNETIC, AND OPTICAL PROPERTIES: Raman Spectroscopic Studies of Pressure-Induced Phase Transitions on 1-Dodecene
NASA Astrophysics Data System (ADS)
Du, Zhi-Xue; Zheng, Hai-Fei
Raman spectroscopic features of 1-dodecene are studied in a moissanite anvil cell up to 3.0 GPa at 21░C. Our data indicate that 1-dodecene is chemically stable under the experimental condition because no new Raman peaks can be observed. However, two significant discontinuities in the plots of Raman shift versus pressure indicate two phase transitions of 1-dodecene. One is liquid-solid transition at pressure of about 500 MPa, the other is solid-solid phase transition at pressure from 1300 to 1550 MPa. The latter is considered to be related to the orientational change of the plane structure of ethylene. A rudimentary phase diagrams for 1-dodecene, n-pentane, n-hexane are proposed based on the results and previous data.
Dynamics of CN+alkane reactions by crossed-beam dc slice imaging
Huang Cunshun; Li Wen; Estillore, Armando D.; Suits, Arthur G. [Department of Chemistry, Wayne State University, Detroit, Michigan 48202 (United States)
The hydrogen atom abstraction reactions of CN (X {sup 2}{sigma}{sup +}) with alkanes have been studied using the crossed molecular beam technique with dc slice ion imaging at collision energies of 7.5 and 10.8 kcal/mol. The product alkyl radical images were obtained via single photon ionization at 157 nm for the reactions of CN (X {sup 2}{sigma}{sup +}) with n-butane, n-pentane, n-hexane, and cyclohexane. From analysis of the images, we obtained the center-of-mass frame product angular distributions and translational energy distributions directly. The results indicate that the products are largely backscattered and that most of the available energy ({approx}80%-85%) goes to the internal energy of the products. The reaction dynamics is discussed in light of recent kinetics data, theoretical calculations, and results for related halogen and oxygen atom reactions.
Effects on sorption and diffusion in PTMSP and TMSP/TMSE copolymers of free volume changes due to polymer ageing
NASA Astrophysics Data System (ADS)
Baschetti, M. Giacinti; Ghisellini, M.; Quinzi, M.; Doghieri, F.; Stagnaro, P.; Costa, G.; Sarti, G. C.
Solubility isotherms for n-pentane and n-hexane were measured in pure poly[1-(trimethylsilyl)-1-propyne] (PTMSP) and in 1-trimethylsilyl-1-propyne/1-trimethylsilyl-1- n-hexyne 70/30 copolymer, using freshly prepared samples as well as aged films, at different temperatures. The experimental values of penetrant diffusivity, mobility and heat of mixing have been reported and discussed, based on direct positron annihilation lifetime spectroscopy information, Dual Mode Sorption Model and Non-Equilibrium Lattice Fluid model. The ageing effect is more pronounced in PTMSP, where it leads to a significant solubility and diffusivity reduction, than in the copolymer where the effect is less important. In the activity range inspected the diffusion coefficient and the heat of mixing are almost concentration independent for PTMSP, while they increase appreciably with concentration in the copolymer, as an effect of the great difference in the free volume present in the two matrices.
Effects of light and copper ions on volatile aldehydes of milk and milk fractions
Jeno, W.; Bassette, R.; Crang, R.E.
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.
Natural and synthetic oviposition stimulants forCatolaccus grandis (Burks) females.
Guerra, A A; Martinez, S; Sonia Del Rio, H
Oviposition behavior was elicited fromCatolaccus grandis (Burks) (Hymenoptera: Pteromalidae) females, an ectoparasitoid of the boll weevil,Anthonomus grandis Boheman (Coleoptera: Curculionidae), by smears of freshly cut cotton bolls or smears of extracts prepared with boll weevil damaged or undamaged cotton boll tissues. Oviposition behavior was also elicited fromC. grandis females by smears made withn-pentane,n-hexane,n-heptane, and isooctane. This is the first report of oviposition behavior elicited for any parasitoid by these short-chain saturated hydrocarbons (alkanes), introducing a new concept on the chemical mediation of parasitoid behavior during host selection. Oviposition behavior was also elicited fromC. grandis females by volatiles emanating from an artificial diet devoid of insect components that was specifically developed for the in vitro rearing of ectoparasitoids. The possible use of a synergistic combination ofn-hexane and diet to optimize the mechanized production of noncontaminated eggs is also discussed. PMID:24242653
Some aspects of TLC in homogenous magnetic fields.
Malinowska, Irena; Studzi?ski, Marek; Malinowski, Henryk
This article consists of two parts. First part is a short review about the role of magnetic phenomena in natural environment, human surroundings, and his activities such as science, engineering, and medicine. The second part of the article presents a set of experiments, their results, and data obtained in a static homogenous magnetic field, generated by a pair of permanent magnets and outside it. Adsorption chromatographic systems were investigated: as chromatographed substances - polyaromatic hydrocarbon (PAH), as stationary phase - silica gel 60, as monocomponent mobile phases - n-hexane, n-heptane, n-octane, and benzene were used and binary mobile phases n-hydrocarbons - benzene. Magnetic field influences retention and efficiency of investigated chromatographic systems. Experimental data analysis (RF, N) allows us to propose some explanations of the differences between experiment results performed in induced magnetic field and outside it, and in consequence on the changes in the interfacial phenomena induced by field presence. PMID:25363353
A viscometric study of tuning micellar morphology by organic additives
Ziya Ahmad Khan; Sanjeev Kumar; Tanweer Ahmad
The micellar morphology in aqueous 0.2ĀM sodium dodecyl sulfate (SDS) solutions has been studied in the simultaneous presence\\u000a of organic salts (anilinium hydrochloride, AHC; ortho-toluidine hydrochloride, oTHC; para-toluidine hydrochloride, pTHC) and aliphatic alcohols (n-butanol, C4OH; n-pentanol, C5OH; n-hexanol, C6OH; n-heptanol, C7OH), aliphatic amines (n-butylamine, C4NH2; n-pentylamine, C5NH2; n-hexylamine, C6NH2; n-heptylamine, C7NH2), or hydrocarbons (n-hexane, C6H; n-heptane, C7H) by viscosity measurements
Empirical and Semi-theoretical Methods for Predicting the Viscosity of Binary n-Alkane Mixtures
NASA Astrophysics Data System (ADS)
Yucel, H. G.
In this study, empirical and semi-theoretical methods for predicting the viscosity of binary mixtures of n-alkanes are presented at atmospheric pressure and in the temperature range from 288 to 333 K. In the empirical viscosity calculation method, a modified version of the Andrade equation and a simple mixture rule are used. The proposed semi-theoretical method employs both the EnskogÆs hard-sphere theory for dense fluids and the principle of corresponding states. The viscosities of binary mixtures of n-heptane with n-hexane and n-nonane covering different compositions were calculated using these methods which require only critical properties and the normal boiling point as input data. The predictions were compared with accurate experimental data in the literature. Highly satisfactory results were obtained. The percent average absolute deviations amount to 1.2 and 0.9% utilizing the empirical and semi-theoretical viscosity methods, respectively, for 27 data points.
Lipase-catalyzed synthesis of capsaicin analogs by transacylation of capsaicin with natural oils or fatty acid derivatives in n -hexane
Kenji Kobata; Mamiko Kobayashi; Yukiyoshi Tamura; Shozo Miyoshi; Susumu Ogawa; Tatsuo Watanabe
Transacylation of capsaicin with triolein using a commercial lipase gave olvanil in an 85% yield at 70?░C for 144Āh. When olive oil was employed, the major product was olvanil (62%). Safflower oil gave a mixture of olvanil (39%) and linoleoyl vanillylamide (32%). Perilla oil gave linolenoyl vanillylamide (13%). Myristic acid and its methyl ester could be used as an acyl
The effect of varying oven temperatures and residence times on thermal desorption of n-hexane and 1-hexene from diffusive organic vapor dosimetersĀ
Steele, Kenneth Garnett
of suitable adsorbent medium, such as activated charcoal or silica gel. This method proved highly reliable, in that a relatively constant sampling flowrate could be held for as long as eight hours. However, the method also presented The citations used... the ability to adsorb organic compounds in the liquid phase. This property was demonstrated by Lowitz in 1785 by observing that charcoal. can decolorize many liquids. Hunter's work in 1865 demonstrated the (6) ability of coconut char to adsorb gases. A use...
Influence of ensemble size on CO chemisorption and catalytic n-hexane conversion by Au-Pt(111) bimetallic single-crystal surfaces
J. W. A. Sachtler; G. A. Somorjai
Deposition of gold (Au) on platinum (Pt) near 300 K produces an epitaxial Au layer consisting of two-dimensional island which leave large ensembles of Pt(111) uncovered. With increasing coverage, the islands grow until the monolayer is completed, before the second layer begins to form. High temperature annealing of Pt(111) surface covered by several layers of gold produces a surface alloy
Headspace solid-phase microextraction and gas chromatographic-mass spectrometric screening for volatile hydrocarbons in blood.
Liu, J; Hara, K; Kashimura, S; Kashiwagi, M; Hamanaka, T; Miyoshi, A; Kageura, M
Optimization for headspace solid-phase microextraction (SPME) was studied with a view to performing gas chromatographic-mass spectrometric (GC-MS) screening of volatile hydrocarbons (VHCs) in blood. Twenty hydrocarbons comprising aliphatic hydrocarbons ranging from n-hexane to n-tridecane, and aromatic hydrocarbons ranging from benzene to trimethylbenzenes were used in this study. This method can be used for examining a burned body to ascertain whether the victim had been alive or not when the burning incident took place. n-Hexane, n-heptane and benzene, the main indicators of gasoline components, were found as detectable peaks through the use of cryogenic oven trapping upon SPME injection into a GC-MS instrument. The optimal screening procedure was performed as follows. The analytes in the headspace of 0.2 g of blood mixed with 0.8 ml of water plus 0.2 microg of toluene-d8 at -5 degrees C were adsorbed to a 100-microm polydimethylsiloxane (PDMS) fiber for 30 min, and measured using the full-mass-scanning GC-MS method. The lower detection limits of all the compounds were 0.01 microg per 1 g of blood. Linearities (r2) within the range 0.01 to 4 microg per 1 g of blood were only obtained for the aromatic hydrocarbons at between 0.9638 (pseudocumene) and 0.9994 (toluene), but not for aliphatic hydrocarbons at between 0.9392 (n-tridecane) and 0.9935 (n-hexane). The coefficients of variation at 0.2 microg/g were less than 8.6% (n-undecane). In conclusion, this method is feasible for the screening of volatile hydrocarbons from blood in forensic medicine. PMID:11087082
A Comparison of the Reactivity of ōNonequilibratedö and ōEquilibratedö V¢P¢O Catalysts: Structural Evolution, Surface Characterization, and Reactivity in the Selective Oxidation of n-Butane and n-Pentane
S. Albonetti; F. Cavani; F. Trifir"; P. Venturoli; G. Calestani; M. L¾pez Granados; J. L. G. Fierro
Changes occurring on thermal treatment of the precursor of vanadium\\/phosphorus mixed oxide, the industrial catalyst for the oxidation ofn-butane, were studied. The precursor was mixed with stearic acid, used as an organic binder for pelletization of the powder. The calcination of the precursor leads to a partially oxidized compound, constituted of an amorphous VIV¢P mixed oxide and a crystalline hydrated
Quantitative analysis of volatile organic compounds released and consumed by rat L6 skeletal muscle cells in vitro.
Mochalski, Pawe?; Al-Zoairy, Ramona; Niederwanger, Andreas; Unterkofler, Karl; Amann, Anton
Knowledge of the release of volatile organic compounds (VOCs) by cells provides important information on the origin of VOCs in exhaled breath. Muscle cells are particularly important, since their release of volatiles during the exertion of an effort contributes considerably to breath concentration profiles. Presently, the cultivation of human skeletal muscle cells is encountering a number of obstacles, necessitating the use of animal muscle cells in in vitro studies. Rat L6 skeletal muscle cells are therefore commonly used as a model for studying the molecular mechanisms of human skeletal muscle differentiation and functions, and facilitate the study of the origin and metabolic fate of the endogenously produced compounds observed in breath and skin emanations. Within this study the production and uptake of VOCs by rat L6 skeletal muscle cells were investigated using gas chromatography with mass spectrometric detection, combined with head-space needle trap extraction as the pre-concentration technique (HS-NTE-GC-MS). Seven compounds were found to be produced, whereas sixteen species were consumed (Wilcoxon signed-rank test, pĀ<Ā0.05) by the cells being studied. The set of released volatiles included two ketones (2-pentanone and 2-nonanone), two volatile sulphur compounds (dimethyl sulfide and methyl 5-methyl-2-furyl sulphide), and three hydrocarbons (2-methyl 1-propene, n-pentane and isoprene). Of the metabolized species there were thirteen aldehydes (2-propenal, 2-methyl 2-propenal, 2-methyl propanal, 2-butenal, 2-methyl butanal, 3-methyl butanal, n-pentanal, 2-methyl 2-butenal, n-hexanal, benzaldehyde, n-octanal, n-nonanal and n-decanal), two esters (n-propyl propionate and n-butyl acetate), and one volatile sulphur compound (dimethyl disulfide). The possible metabolic pathways leading to the uptake and release of these compounds by L6 cells are proposed and discussed. An analysis of the VOCs showed them to have huge potential for the identification and monitoring of some molecular mechanism and conditions. PMID:25307263
The Measurement of Laminar Burning Velocities and Markstein Numbers for Iso-octane¢Air and Iso-octane¢n-Heptane¢Air Mixtures at Elevated Temperatures and Pressures in an Explosion Bomb
D. Bradley; R. A. Hicks; M. Lawes; C. G. W. Sheppard; R. Woolley
Spherically expanding flames have been employed to measure flame speeds, from which have been derived corresponding laminar burning velocities at zero stretch rate. Two burning velocities are defined, one based upon the rate of propagation of the flame front, the other on the rate of formation of burned gas. To express the effects of flame stretch upon burning velocity, Markstein
Atmos. Chem. Phys., 14, 14631483, 2014 www.atmos-chem-phys.net/14/1463/2014/
Meskhidze, Nicholas
, propane, i-butane, n- butane, i-pentane, and n-pentane by (a) reconstructing at- mospheric mole fractions increases in the ratios of the isomeric iso-/n-butane and iso-/n-pentane ratios. Com- parison
Modeling VOC Sorption and Transport in Glassy Polymeric Membranes
NASA Astrophysics Data System (ADS)
De Angelis, Maria Grazia; Olivieri, Luca; Sarti, G. C.
In this work we evaluated the sorption, diffusion and permeation of a series of volatile organic compounds (VOCs) (acetone, n-butane, n-pentane, n-hexane, ethanol, methanol, chloroform and toluene) into glassy polymers of increasing fractional free volume (FFV): Polycarbonate (PC), Amorphous Teflon AF1600 and AF2400, poly-trimethylsilyl norbornene (PTMSN) and poly[1-(trimethylsilyl)-1-propyne] (PTMSP). Based on some experimental data of sorption and diffusion, and on theoretical and empirical models for the solubility and diffusion coefficients, the permeability for vapor/N2 mixtures was evaluated. These parameters are useful for the membrane separation processes and for other applications such as chemical sensors. The ideal separation factors of glassy polymeric membranes versus mixtures of VOCs and N2 were estimated at various pressures and compositions and at 25░ C. The selectivity vs. permeability maps for the mixtures considered were plotted, showing that some of these materials show potentially the same selective ability of rubbery polymeric films. In particular it is shown that, the higher the FFV, the better the vapor/gas selectivity.
Biodegradation of petroleum hydrocarbon vapors: laboratory studies on rates and kinetics in unsaturated alluvial sand
NASA Astrophysics Data System (ADS)
H÷hener, Patrick; Duwig, Cķline; Pasteris, Gabriele; Kaufmann, Karin; Dakhel, Nathalie; Harms, Hauke
Predictions of natural attenuation of volatile organic compounds (VOCs) in the unsaturated zone rely critically on information about microbial biodegradation kinetics. This study aims at determining kinetic rate laws for the aerobic biodegradation of a mixture of 12 volatile petroleum hydrocarbons and methyl tert-butyl ether (MTBE) in unsaturated alluvial sand. Laboratory column and batch experiments were performed at room temperature under aerobic conditions, and a reactive transport model for VOC vapors in soil gas coupled to Monod-type degradation kinetics was used for data interpretation. In the column experiment, an acclimatization of 23 days took place before steady-state diffusive vapor transport through the horizontal column was achieved. Monod kinetic parameters Ks and vmax could be derived from the concentration profiles of toluene, m-xylene, n-octane, and n-hexane, because substrate saturation was approached with these compounds under the experimental conditions. The removal of cyclic alkanes, isooctane, and 1,2,4-trimethylbenzene followed first-order kinetics over the whole concentration range applied. MTBE, n-pentane, and chlorofluorocarbons (CFCs) were not visibly degraded. Batch experiments suggested first-order disappearance rate laws for all VOCs except n-octane, which decreased following zero-order kinetics in live batch experiments. For many compounds including MTBE, disappearance rates in abiotic batch experiments were as high as in live batches indicating sorption. It was concluded that the column approach is preferable for determining biodegradation rate parameters to be used in risk assessment models.
Distributions of C 2-C 6 hydrocarbons over the western North Pacific and eastern Indian Ocean
NASA Astrophysics Data System (ADS)
Saito, T.; Yokouchi, Y.; Kawamura, K.
Atmospheric nonmethane hydrocarbons (NMHCs: C 2-C 6) were measured over the western North Pacific and eastern Indian Ocean between 25░N and 40░S during oceanographic cruise from December 1996 to February 1997 using a fused-silica-lined stainless-steel canister and GC technique. Averaged mixing ratios of individual NMHCs were 0.61 ppbv (ethane), 0.42 ppbv (ethylene), 0.17 ppbv (acetylene), 0.24 ppbv (propane), 0.60 ppbv (propylene), 0.07 ppbv ( i-butane), 0.13 ppbv ( n-butane), 0.04 ppbv ( i-pentane), 0.06 ppbv ( n-pentane), and 0.06 ppbv ( n-hexane). Although there are few reported data available for comparison in these regions of marine boundary layer, mixing ratios of the NMHCs are within the range of previous results reported in the similar latitudes from the Atlantic and Pacific Ocean. NMHCs with lifetimes more than a week (C 2-C 4 alkanes and acetylene) showed a significant latitudinal decrease from north to south in the Northern Hemisphere, suggesting an important source strength in East Asian region. In contrast, NMHCs with lifetimes less than a week (alkenes and C 5-C 6 alkanes) did not show any significant latitudinal trends. Based on a comparison with the results of the backward trajectories for 2 days, light alkenes were suggested to be derived from ocean surfaces.
A predictive method for crude oil volatile organic compounds emission from soil: evaporation and diffusion behavior investigation of binary gas mixtures.
Wang, Haijing; Fischer, Thomas; Wieprecht, Wolfgang; M÷ller, Detlev
Due to their mobility and toxicity, crude oil volatile organic compounds (VOCs) are representative components for oil pipeline contaminated sites detection. Therefore, contaminated location risk assessment, with airborne light detection and ranging (LIDAR) survey, in particular, requires ground-based determinative methods for oil VOCs, the interaction between oil VOCs and soil, and information on how they diffuse from underground into atmosphere. First, we developed a method for determination of crude oil VOC binary mixtures (take n-pentane and n-hexane as examples), taking synergistic effects of VOC mixtures on polydimethylsiloxane (PDMS) solid-phase microextraction (SPME) fibers into consideration. Using this method, we further aim to extract VOCs from small volumes, for example, from soil pores, using a custom-made sampling device for nondestructive SPME fiber intrusion, and to study VOC transport through heterogeneous porous media. Second, specific surface Brunauer-Emmett-TellerĀ(BET) analysis was conducted and used for estimation of VOC isotherm parameters in soil. Finally, two models were fitted for VOC emission prediction, and the results were compared to the experimental emission results. It was found that free diffusion mode worked well, and an empirical correction factor seems to be needed for the other model to adapt to our condition for single and binary systems. PMID:25572270
[Cloning and expression of organic solvent tolerant lipase gene from Staphylococcus saprophyticus M36].
Tang, Yanchong; Lu, Yaping; L³, Fengxia; Bie, Xiaomei; Guo, Yao; Lu, Zhaoxin
Lipases are important biocatalysts that are widely used in food processing and bio-diesel production. However, organic solvents could inactivate some lipases during applications. Therefore, the efficient cloning and expression of the organic solvent-tolerant lipase is important to its application. In this work, we first found out an organic solvent-tolerant lipase from Staphylococcus saprophyticus M36 and amplified the 741 bp Lipase gene lip3 (GenBank Accession No. FJ979867), by PCR, which encoded a 31.6 kD polypeptide of 247 amino acid residues. But the lipase shared 83% identity with tentative lip3 gene of Staphylococcus saprophyticus (GenBank Accession No. AP008934). We connected the gene with expression vector pET-DsbA, transformed it into Escherichia coli BL21 (DE3), and obtained the recombinant pET-DsbA-lip3. With the induction by 0.4 mmol/L of isopropyl beta-D-thiogalactopyranoside at pH 8.0, OD600 1.0, 25 degrees C for 12 h, the lipase activity reached up to 25.8 U/mL. The lipase expressed was stable in the presence of methanol, n-hexane, and isooctane, n-heptane. PMID:20352979
Infrared band intensities of saturated hydrocarbons
NASA Technical Reports Server (NTRS)
Pinkley, L. W.; Sethna, P. P.; Williams, D.
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.
High pressure droplet burning experiments in reduced gravity
NASA Technical Reports Server (NTRS)
Chauveau, Christian; Goekalp, Iskender
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).
Biodiesel production using waste frying oil
Charpe, Trupti W. [Chemical Engineering Department, Institute of Chemical Technology, Matunga, Mumbai 400 019 (India); Rathod, Virendra K., E-mail: email@example.com [Chemical Engineering Department, Institute of Chemical Technology, Matunga, Mumbai 400 019 (India)
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.
Investigation of thermodynamic properties of poly(methyl methacrylate-co-n-butylacrylate-co-cyclopentyl styryl-polyhedral oligomeric silsesquioxane) by inverse gas chromatography.
Zou, Qi-Chao; Zhang, Shi-Ling; Wang, Shi-Min; Wu, Li-Min
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
Volatile organic compounds in the air of Izmir, Turkey
NASA Astrophysics Data System (ADS)
Muezzinoglu, Aysen; Odabasi, Mustafa; Onat, Levent
A sampling program was conducted to determine the ambient VOC levels in the city of Izmir, Turkey during daytime and overnight periods between mid-August and mid-September 1998. Sampling sites were selected at high-density traffic roads and junctions far from stationary VOC sources. Samples were analyzed for benzene, toluene, m, p-xylene and o-xylene (BTX), alkylbenzenes (ethylbenzene, 1,3,5-trimethylbenzene, 1,2,4-trimethylbenzene), n-hexane and, n-heptane. Results were compared with similar data from other cities around the world and for probable health dangers and sources of the compounds. Results of this study indicated that Izmir has rather high ambient BTX concentrations compared to many polluted cities in the world. Toluene was the most abundant VOC in Izmir air and was followed by xylenes, benzene and alkylbenzenes, respectively. All were strongly dependent on the expected daily variations of traffic flow in the city. The concentrations of other VOCs correlated well with benzene concentration at most sampling sites, excluding Gumuldur station indicating that ambient VOC levels were mainly affected by motor vehicle emissions. The toluene-to-benzene ratios for urban and non-urban sites were in good agreement with previously reported values, indicating a good relationship between the motor vehicle emissions and ambient VOC levels.
D/H Isotope Ratio Measurements of Atmospheric Volatile Organic Compounds
NASA Astrophysics Data System (ADS)
Meisehen, Thomas; B³hler, Fred; Koppmann, Ralf; Krebsbach, Marc
Analysis of isotope ratios in atmospheric volatile organic compounds (VOC) is a reliable method to allocate their sources, to estimate atmospheric residence times and investigate physical and chemical processes on various temporal and spatial scales. Most investigations yet focus on carbon isotope ratios. Certainly more detailed information can be gained by the ratio of deuterium (D) to hydrogen (H) in VOC, especially due to the high mass ratio. Combining measurements of carbon and hydrogen isotopes could lead to considerable improvement in our understanding of atmospheric processes. For this purpose we set up and thoroughly characterised a gas chromatograph pyrolysis isotope ratio mass spectrometer to measure the D/H ratio in atmospheric VOC. From a custom-made gas standard mixture VOC were adsorbed on Tenax«TA which has the advantage that CO2 is not preconcentrated when measuring ambient air samples. Our results show that the pyrolysis method has significant impact on the D/H ratios. A pyrolysis temperature of at least 1723 K and conditioning of the ceramic tube on a regular basis is essential to obtain reproducible D/H isotope ratios. For an independent comparison D/H ratios of the pure VOC used in the gas standard were determined using elemental analysis by Agroisolab (J³lich, Germany). Comparisons of 10 VOC show perfect agreement within the standard deviations of our measurements and the errors given by Agroisolab, e.g. for n-pentane, toluene, 4-methyl-2-pentanone and n-octane. A slight mean difference of 5.1 o was obtained for n-heptane while significant mean differences of 15.5 o and 20.3 o arose for 1,2,4-trimethylbenzene and isoprene, respectively. We further demonstrate the stability of our system and show that the sample preparation does not affect the isotope ratios. Moreover the applicability of our system to ambient air samples is demonstrated.
Transferable Potentials for Phase Equilibria. 4. United-Atom Description of Linear and Branched Alkenes and Alkylbenzenes
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.
Extraction mechanism of Sc(III) and separation from Th(IV), Fe(III) and Lu(III) with bis(2,4,4-trimethylpentyl)phosphinic acid in n-hexane from sulphuric acid solutions
Wang, Chun; Li, Deqian (Changchun Inst. of Applied Chemistry and Physics (China))
The extraction equilibrium data of sulphuric acid and scandium(III) with bis(2,4,4-trimethylpentyl)phosphinic acid (H[BTMPP]) from sulphuric acid solutions have been obtained. There are two extraction mechanisms of scandium(III) with H[BTMPP] at different ranges of aqueous acidity. The extraction of Sc(III) proceeds according to a cation exchange reaction at lower aqueous acidity and to a solvating reaction at higher acidity. The practicability of separating Sc(III) from Th(IV),Fe(III) and Lu(III) by controlling the aqueous acidity was discussed. The effect of temperature on extraction of Sc(III) was observed and thermodynamic functions were calculated. IR and NMR spectra were made for organic extracts. The extraction characteristics of H[BTMPP] and di(2-ethylhexyl)phosphinic acid (H[DEHP]) were contrasted to obtain more information about extraction with H[BTMPP]. 12 refs., 6 figs., 1 tab.
A comparison of the reactivity of {open_quotes}nonequilibrated{close_quotes} and {open_quotes}equilibrated{close_quotes} V-P-O catalysts: Structural evolution, surface characterization, and reactivity in the selective oxidation of n-butane and n-pentane
S. Albonetti; F. Cavani; F. Trifiro; P. Venturoli
Structural alteration as a result of thermal treatment of VOHPOŌ┬Ę4HŌO was studied. Calcination induces partial oxidization, resulting in a phase composed of an amorphous V{sup IV}-P mixed oxide and a crystalline hydrated V{sup V}-P-O phase. When left in a 1% hydrocarbon\\/air stream for 100 h leads to a{open_quotes}nonequilibrated{close_quotes} catalyst, and after 1000 h to the {open_quotes}equilibrated{close_quotes} catalyst. Catalytic activity of
Characteristics of volatile organic compounds (VOCs) emitted from a petroleum refinery in Beijing, China
NASA Astrophysics Data System (ADS)
Wei, Wei; Cheng, Shuiyuan; Li, Guohao; Wang, Gang; Wang, Haiyan
This study made a field VOCs (volatile organic compounds) measurement for a petroleum refinery in Beijing by determining 56 PAMS VOCs, which are demanded for photochemical assessment in US, and obtained the characteristics of VOCs emitted from the whole refinery and from its inner main devices. During the monitoring period, this refinery brought about an average increase of 61Āppbv in the ambient TVOCs (sum of the PAMS VOCs) at the refinery surrounding area, while the background of TVOCs there was only 10-30Āppbv. In chemical profile, the VOCs emitted from the whole refinery was characteristic by isobutane (8.7%), n-butane (7.9%), isopentane (6.3%), n-pentane (4.9%%), n-hexane (7.6%), C6 branched alkanes (6.0%), propene (12.7%), 1-butene (4.1%), benzene (7.8%), and toluene (5.9%). On the other hand, the measurement for the inner 5 devices, catalytic cracking units (CCU2 and CCU3), catalytic reforming unit (CRU), tank farm (TF), and wastewater treatment(WT), revealed the higher level of VOCs pollutions (about several hundred ppbv of TVOCs), and the individual differences in VOCs chemical profiles. Based on the measured speciated VOCs data at the surrounding downwind area, PMF receptor model was applied to identify the VOCs sources in the refinery. Then, coupling with the VOCs chemical profiles measured at the device areas, we concluded that CCU1/3 contributes to 25.9% of the TVOCs at the surrounding downwind area by volume, followed by CCU2 (24.7%), CRU (18.9%), TF (18.3%) and WT (12.0%), which was accordant with the research of US EPA (2008). Finally, ozone formation potentials of the 5 devices were also calculated by MIR technique, which showed that catalytic cracking units, accounting for about 55.6% to photochemical ozone formation, should be given the consideration of VOCs control firstly.
Investigating the validity of the Knudsen prescription for diffusivities in a mesoporous covalent organic framework
Krishna, Rajamani; van Baten, Jasper M.
Molecular dynamics (MD) simulations were performed to determine the self-diffusivity (D{sub i,self}) and the Maxwell¢Stefan diffusivity (?{sub I}) 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 (?{sub I}(0)) is consistently lower, by up to a factor of 10, than the Knudsen diffusivity (D{sub i,Kn}) values. The ratio ?{sub I}(0)/D{sub i,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 ?{sub I}(0)/D{sub i,Kn}. The diffusion selectivity, which is defined by the ratio D{sub 1,self}/D{sub 2,self} for binary mixtures, was determined to be significantly different from the Knudsen selectivity (M{sub 2}/M{sub 1}){sup 1/2}, where M{sub I} is the molar mass of species i. For mixtures in which component 2 is more strongly adsorbed than component 1, the expression (D{sub 1,self}/D{sub 2,self})/(M{sub 2}/M{sub 1}){sup 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.
Multidrug resistance in hydrocarbon-tolerant Gram-positive and Gram-negative bacteria.
Stancu, Mihaela Marilena; Grifoll, Magdalena
New Gram-positive and Gram-negative bacteria were isolated from Poeni oily sludge, using enrichment procedures. The six Gram-positive strains belong to Bacillus, Lysinibacillus and Rhodococcus genera. The eight Gram-negative strains belong to Shewanella, Aeromonas, Pseudomonas and Klebsiella genera. Isolated bacterial strains were tolerant to saturated (i.e., n-hexane, n-heptane, n-decane, n-pentadecane, n-hexadecane, cyclohexane), monoaromatic (i.e., benzene, toluene, styrene, xylene isomers, ethylbenzene, propylbenzene) and polyaromatic (i.e., naphthalene, 2-methylnaphthalene, fluorene) hydrocarbons, and also resistant to different antimicrobial agents (i.e., ampicillin, kanamycin, rhodamine 6G, crystal violet, malachite green, sodium dodecyl sulfate). The presence of hydrophilic antibiotics like ampicillin or kanamycin in liquid LB-Mg medium has no effects on Gram-positive and Gram-negative bacteria resistance to toxic compounds. The results indicated that Gram-negative bacteria are less sensitive to toxic compounds than Gram-positive bacteria, except one bacteria belonging to Lysinibacillus genus. There were observed cellular and molecular modifications induced by ampicillin or kanamycin to isolated bacterial strains. Gram-negative bacteria possessed between two and four catabolic genes (alkB, alkM, alkB/alkB1, todC1, xylM, PAH dioxygenase, catechol 2,3-dioxygenase), compared with Gram-positive bacteria (except one bacteria belonging to Bacillus genus) which possessed one catabolic gene (alkB/alkB1). Transporter genes (HAE1, acrAB) were detected only in Gram-negative bacteria. PMID:21478643
Growth of Rhodococcus sp. strain BCP1 on gaseous n-alkanes: new metabolic insights and transcriptional analysis of two soluble di-iron monooxygenase genes.
Cappelletti, Martina; Presentato, Alessandro; Milazzo, Giorgio; Turner, Raymond J; Fedi, Stefano; Frascari, Dario; Zannoni, Davide
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
Growth of Rhodococcus sp. strain BCP1 on gaseous n-alkanes: new metabolic insights and transcriptional analysis of two soluble di-iron monooxygenase genes
Cappelletti, Martina; Presentato, Alessandro; Milazzo, Giorgio; Turner, Raymond J.; Fedi, Stefano; Frascari, Dario; Zannoni, Davide
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 smoABCDŚcoding for Soluble Di-Iron Monooxgenases (SDIMOs) involved in gaseous n-alkanes oxidationŚwere 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
Phase equilibria study of the binary systems (N-hexylisoquinolinium thiocyanate ionic liquid + organic solvent or water).
Kr¾likowska, Marta; Karpi?ska, Monika; Zawadzki, Maciej
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
[Characterization of surface properties of 1-allyl-3-methylimidazolium chloride ionic liquid by inverse gas chromatography].
Chen, Yali; Wang, Qiang; Deng, Lishuang; Zhang, Zhengfang; Tang, Jun
The determination of the dispersive component of surface free energies (gamma(s)d) at different temperatures and Lewis acid-base parameters of 1-allyl-3-methylimidazolium chloride ionic liquid ([AMIM]Cl) were investigated by means of inverse gas chromatography (IGC). Four n-alkanes, including n-hexane (C6), n-heptane (C7), n-octane (C8) and n-nonane (C9), were chosen as the apolar probes to characterize the dispersive component of the surface free energies at 343.15, 353.15, 363.15 and 373.15 K, respectively; and dichloromethane (DCM), trichloromethane (TCM), tetrahydrofuran (THF), ethyl acetate (EtAc), acetone (Acet) as the polar probes to estimate the Lewis acid-base parameters to judge the interactions between [AMIM] Cl and the solvents. The IGC characterizations encompassed the adsorption thermodynamic parameters to acid-base surface interactions, including the standard enthalpy (deltaHa(s)) and the free energy change of adsorption (deltaGa(s)) at different temperatures. The results showed that the Lewis acid parameter Ka of [AMIM] Cl was 0.34, and the base parameter Kb was 1.68, which indicated it was Lewis amphoteric with predominantly basic character. Furthermore, the free energy of adsorption deltaGa(s) was also figured out. It was found that the gamma(s)d of the [AMIM] Cl were 52.26, 50.82, 46.08 and 42.05 mJ/m2 at 343.15, 353.15, 363.15 and 373.15 K, respectively. The results are of great importance to the study of the surface properties and the application of ionic liquid. PMID:23697180
Determination of vapor liquid equilibrium for the ternary iso-propanol/atactic-polypropylene/n-heptane mixture at 105C and 140C, and the binary iso-propanol/atactic-polypropylene mixture at 85C using perturbation gas chromatography / cby Lamar Lane JoffrionĀ
Joffrion, Lamar Lane
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40 CFR 63.1004 - Instrument and sensory monitoring for leaks.
Code of Federal Regulations, 2010 CFR
...parts per million; or a mixture of n-hexane in air at a concentration of approximately...gas other than methane in air or n-hexane in air may be used if the instrument does not respond to methane or n-hexane or if the instrument does not...
Fischer-Tropsch synthesis in supercritical reaction media. [Quarterly] progress report, July 1, 1993--September 30, 1993
Subramaniam, B.
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).
Effects of biomass burning on summertime nonmethane hydrocarbon concentrations in the Canadian wetlands
NASA Technical Reports Server (NTRS)
Blake, D. R.; Smith, T. W., Jr.; Chen, T.-Y.; Whipple, W. J.; Rowland, F. S.
Approximately 900 whole air samples were collected and assayed for selected C2-C10 hydrocarbons and seven halocarbons during the 5-week Arctic Boundary Layer Expedition (ABLE) 3B conducted in eastern Canadian wetland areas. In more than half of the 46 vertical profiles flown, enhanced nonmethane hydrocarbon (NMHC) concentrations attributable to plumes from Canadian forest fires were observed. Urban plumes, also enhanced in many NMHCs, were separately identified by their high correlation with elevated levels of perchloroethene. Emission factors relative to ethane were determined for 21 hydrocarbons released from Canadian biomass burning. Using these data for ethane, ethyne, propane, n-butane, and carbon monoxide enhancements from the literature, global emissions of these four NMHCs were estimated. Because of its very short atmospheric lifetime and its below detection limit background mixing ratio, 1,3-butadiene is an excellent indicator of recent combustion. No statistically significant emissions of nitrous oxide, isoprene, or CFC 12 were observed in the biomass-burning plumes encountered during ABLE 3B. The presence of the short-lived biogenically emitted isoprene at altitudes as high as 3000 m implies that mixing within the planetary boundary layer (PBL) was rapid. Although background levels of the longer-lived NMHCs in this Canadian region increase during the fire season, isoprene still dominated local hydroxyl radical photochemistry within the PBL except in the immediate vicinity of active fires. The average biomass-burning emission ratios for hydrocarbons from an active fire sampled within minutes of combustion were, relative to ethane, ethene, 2.45; ethyne 0.57; propane, 0.25; propene, 0.73; propyne, 0.06; n-butane, 0.09; i-butane, 0.01; 1-butene, 0.14; cis-2-butene, 0.02; trans-2-butene, 0.03; i-butylene, 0.07; 1,3-butadiene, 0.12; n-pentane, 0.05; i-pentane, 0.03; 1-pentene, 0.06; n-hexane, 0.05; 1-hexene, 0.07; benzene, 0.37; toluene, 0.16.
Enhancing chemical identification efficiency by SAW sensor transients through a data enrichment and information fusion strategyŚa simulation study
NASA Astrophysics Data System (ADS)
Singh, Prashant; Yadava, R. D. S.
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.
Solubility of aliphatic hydrocarbons in piperidinium ionic liquids: measurements and modeling in terms of perturbed-chain statistical associating fluid theory and nonrandom hydrogen-bonding theory.
Paduszy?ski, Kamil; Doma?ska, Urszula
Ionic liquids (ILs) reveal many unique properties which make them very interesting for applications in modern "green" technologies. For that reason, detailed knowledge about correlations between the ions' structure, their combinations, and the bulk properties is of great importance. That knowledge can be accessed by reliable measurements and modeling of systems with ILs in terms of various theoretical approaches. In this paper we report new experimental results on liquid-liquid equilibrium (LLE) measurements of 10 binary systems composed of piperidinium ILs [namely, 1-propyl-1-methylpiperidinium bis(trifluoromethylsulfonyl)imide and 1-butyl-1-methylpiperidinium bis(trifluoromethylsulfonyl)imide] and aliphatic hydrocarbons (n-hexane, n-heptane, n-octane, cyclohexane, and cycloheptane). Moreover, new results on liquid density of pure 1-butyl-1-methylpiperidinium bis(trifluoromethylsulfonyl)imide are presented. Upper critical solution temperature type of phase behavior for all studied systems was observed. Decrease of solubility of n-alkane with an increase of its alkyl chain length and increase of solubility when changing linear into cyclic structure of hydrocarbon were detected. LLE modeling of investigated systems was performed in terms of two modern theories, namely, perturbed-chain statistical associating fluid theory (PC-SAFT) and nonrandom hydrogen-bonding theory (NRHB). Pure fluid parameters of the models were obtained from fitting of experimental liquid density and solubility parameter data at ambient pressure and tested against high pressure densities. Then literature values of activity coefficients of n-alkanes and cycloalkanes at infinitely diluted mixtures with ILs were used to optimize binary interaction parameters of the models. Finally, the LLE phase diagrams were calculated with average absolute relative deviations of 4.1% and 3.4% of the IL mole fraction for PC-SAFT and NRHB, respectively. The PC-SAFT and NRHB models were both able to capture phase behavior in a qualitative manner. Both models predict the order in which solubility of hydrocarbon in the IL increases, including the effects of chain length of n-alkane as well as chain length of alkyl substituent in piperidinium cation. Moreover, predicted solubility of cycloalkanes is also higher than that of respective n-alkanes. Our results suggest that the presented approach of PC-SAFT and NRHB modeling can be successfully applied to cross-associating systems as well. In summary, we have shown that relatively good results can be obtained for such complex systems by using quite simple molecular models and combining rules. To the best of our knowledge, this is the very first paper in which such equation-of-state modeling has been adopted for systems with ILs. PMID:21942446
Model Reaction for the in-Situ Characterization of the Hydrogenating and Acid Properties of Industrial Hydrocracking Catalysts
M. Guisnet; C. Thomazeau; J. L. Lemberton; S. Mignard
A kinetic study of o-xylene transformation was carried out on a sulfided NiMo on Y zeolite catalyst during the hydrocracking of a model compound (n-heptane) under the following conditions of the process: high hydrogen pressure (5.7 MPa), presence of nitrogen and sulfur-containing compounds. o-Xylene inhibits n-heptane transformation, which can be explained by a competition for the adsorption on the acid
Syngas production from liquid fuels in a non-catalytic porous burner
A. Pastore; E. Mastorakos
This paper investigates rich combustion of n-heptane, diesel oil, kerosene and rapeseed-oil methyl ester (RME) bio-diesel for the purpose of producing syngas ready for the clean-up stages for fuel-cell applications or for traditional combustor enrichment. Rich flames have been stabilised in a two-layer inert porous medium combustor and a range of equivalence ratios and porous materials have been examined. n-heptane
Evidence for the contribution of methane in the formation of aromatics and soot in fuel-rich pre-mixed combustion
J. F. Roesler; M. Auphan de Tessan; X. Montagne
Experimental results from an isothermal laminar flow reactor at atmospheric pressure are presented on the chemical composition in the post-oxidative region of two sooting fuel-rich pre-mixed mixtures diluted in nitrogen. A base case composed of n-heptane and O2 in N2 at 1425 K with a C\\/O of 2.85 was perturbed by substituting 10% of the carbon in n-heptane with carbon
Evidence of Zinc Protection against 2,5-Hexanedione Neurotoxicity: Correlation of Neurobehavioral Testing with Biomarkers of Excretion
M. Luisa Mateus; Ana P. M. dos Santos; M. Camila C Batorķu
Risk prevention of human exposure against n-hexane neurotoxicity is relevant towards the protective measures to be proposed in occupational toxicology. Metabolic studies have identified 2,5-hexanedione (2,5-HD) as the main neurotoxic metabolite of n-hexane, which reacts with amino groups of lysine in axonal neurofilaments forming 2,5-dimethylpyrrole adducts, which are responsible for n-hexane neurotoxicity. In the present study, we have investigated the
Transport properties of nonelectrolyte liquid mixturesŚI. Viscosity coefficients for n-alkane mixtures at saturation pressure from 283 to 378 K
J. H. Dymond; K. J. Young
Viscosity coefficient measurements at saturation pressure are reported for n-hexane + n-hexadecane, n-hexane + n-octane + n-hexadecane, and n-hexane + n-octane + n-dodecane + n-hexadecane at temperatures from 283 to 378 K. The results show that the Congruence Principle applies to the molar excess Gibbs free energy of activation for flow, ?*GE, at temperatures other than 298 K. However, curves
Transport properties of nonelectrolyte liquid mixtures---I. Viscosity coefficients for n-alkane mixtures at saturation pressure from 283 to 378 K
J. H. Dymond; K. J. Young
Viscosity coefficient measurements at saturation pressure are reported for n-hexane + n-hexadecane, n-hexane + n-octane + n-hexadecane, and n-hexane + n-octane + n-dodecane + n-hexadecane at temperatures from 283 to 378 K. The results show that the Congruence Principle applies to the molar excess Gibbs free energy of activation for flow, delta* G E, at temperatures other than 298 K.
Electron Transport in Paracoccus Halodenitrificans and the Role of Ubiquinone
NASA Technical Reports Server (NTRS)
Hochstein, L. I.; Cronin, S. E.
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.
Electron transport in Paracoccus halodenitrificans and the role of Ubiquinone
NASA Technical Reports Server (NTRS)
Hochstein, L. I.; Cronin, S. E.
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.
64 FR 26315 - Guidelines Establishing Test Procedures for the Analysis of Oil and Grease and Non-Polar Material...
Federal Register 2010, 2011, 2012, 2013, 2014
...Non-Polar Material Under the Clean Water Act and Resource Conservation...for use in EPA's Clean Water Act (CWA) programs. This...n-hexane include: the lower density that causes n-hexane to float on the water sample making extraction...
40 CFR 265.1063 - Test methods and procedures.
Code of Federal Regulations, 2010 CFR
...10 ppm of hydrocarbon in air). (ii) A mixture of methane or n-hexane and air at a concentration of approximately, but less than, 10,000 ppm methane or n-hexane. (5) The instrument probe shall be traversed around all...
40 CFR 61.245 - Test methods and procedures.
Code of Federal Regulations, 2010 CFR
...ppm of hydrocarbon in air); and (ii) A mixture of methane or n-hexane and air at a concentration of approximately, but less than, 10,000 ppm methane or n-hexane. (5) The instrument probe shall be traversed around all...
40 CFR 264.1063 - Test methods and procedures.
Code of Federal Regulations, 2010 CFR
...10 ppm of hydrocarbon in air). (ii) A mixture of methane or n-hexane and air at a concentration of approximately, but less than, 10,000 ppm methane or n-hexane. (5) The instrument probe shall be traversed around all...
40 CFR 60.696 - Performance test methods and procedures and compliance provisions.
Code of Federal Regulations, 2010 CFR
...hydrocarbon in air), and (2) A mixture of either methane or n-hexane and air at a concentration of approximately, but less than, 10,000 ppm methane or n-hexane. (c) The owner or operator shall conduct a performance test...
21 CFR 177.1610 - Polyethylene, chlorinated.
Code of Federal Regulations, 2010 CFR
...chlorination of polyethylene conforming to the density, maximum n- hexane extractable fraction, and maximum xylene soluble fraction...and has a 7.0 percent maximum extractable fraction in n -hexane at 50 ░C, as determined by the method described in ¦...
Low severity upgrading of F-T waxes with solid superacids. Quarterly report, March 1, 1993--May 31, 1993
Tierney, J.W.; Wender, I.
The upgrading of Fischer-Tropsch waxes with solid superacids continued this quarter, the isomerization and hydrocracking of n-pentane were examined by in situ FT-IR. It was found that the intensity of protonic acid sites was weakened as n-pentane was introduced into the IR cell, indicating that protonic acid sites tend to donate a proton to n-paraffins. There was no evidence of olefinic intermediates. It is likely that, as we previously proposed, isomerization and hydrocracking over Pt/ZrO{sub 2}/SO{sub 4} catalyst proceed through initial protonation of n-alkanes to form carbonium ions which are then isomerized and hydrocracked.
Modeling the Auto-Ignition of Biodiesel Blends with a Multi-Step Model
Toulson, Dr. Elisa [Michigan State University, East Lansing; Allen, Casey M [Michigan State University, East Lansing; Miller, Dennis J [Michigan State University, East Lansing; McFarlane, Joanna [ORNL; Schock, Harold [Michigan State University, East Lansing; Lee, Tonghun [Michigan State University, East Lansing
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.
Synergistic extraction of rare earths by mixture of bis(2,4,4-trimethylpentyl)phosphinic acid and Sec-nonylphenoxy acetic acid
Xiaobo Sun; Jinping Wang; Deqian Li; Hongfei Li
Synergistic extraction of trivalent rare earths (RE=Sc, Y, La, Gd, Yb) from hydrochloride medium using mixture of bis(2,4,4-trimethylpentyl)phosphinic acid (HL, Cyanex272) and Sec-nonylphenoxy acetic acid (HA, CA-100) in n-heptane has been studied. The synergistic enhancement coefficients were observed for La (1.30), Gd (1.97), Y (3.59), Yb (8.21) and Sc (14.41). The results indicated yttrium was extracted into n-heptane as YH5A4L4
Evaluation of the limit-of-detection capability of carbon black-polymer composite sensors for volatile breath biomarkers
Nae Kyoung Kang; Tae Sun Jun; Duc-Duong La; Je Hoon Oh; Yong Woo Cho; Yong Shin Kim
Six composite sensors were prepared by casting a solution of different polymers and conductive carbon black nanoparticles on a glass substrate with two comb-shape Au electrodes. The chemoresistive response and background noise level were measured as a function of concentration upon exposure to various breath biomarker compounds: acetic acid, toluene, ethanol, acetone, n-pentane, and isoprene. All sensors exhibited a good
21 CFR 178.3010 - Adjuvant substances used in the manufacture of foamed plastics.
Code of Federal Regulations, 2011 CFR
...75-37-6) For use as a blowing agent in polystyrene. Isopentane For use as a blowing agent in polystyrene. n -Pentane Do. 1,1,2...only as a blowing agent adjuvant in polystyrene at a level not to exceed 0.3...
21 CFR 178.3010 - Adjuvant substances used in the manufacture of foamed plastics.
Code of Federal Regulations, 2010 CFR
...75-37-6) For use as a blowing agent in polystyrene. Isopentane For use as a blowing agent in polystyrene. n -Pentane Do. 1,1,2...only as a blowing agent adjuvant in polystyrene at a level not to exceed 0.3...
A predictive method for volatile organic compounds emission from soil: Evaporation and diffusion behavior investigation of a representative component of crude oil.
Wang, Haijing; Fischer, Thomas; Wieprecht, Wolfgang; M÷ller, Detlev
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
SUPPORTING INFORMATION An MCM modeling study of nitryl chloride (ClNO2) impacts on oxidation,
Meskhidze, Nicholas
methacrolein 10 10 propanal 90 20 butanal 20 4 ethane 3120 440 propane propane 1940 330 i-butane i-butane 510 70 n-butane n-butane 1200 190 i-pentane 780 100 n-pentane n-petane 350 40 hexane 250 30 nonane 40 2
Conservative and dissipative force field for simulation of coarse-grained alkane molecules: A bottom-up approach
Trķment, Sķbastien; Rousseau, Bernard, E-mail: email@example.com [Laboratoire de Chimie-Physique, UMR 8000 CNRS, Universitķ Paris-Sud, Orsay (France)] [Laboratoire de Chimie-Physique, UMR 8000 CNRS, Universitķ Paris-Sud, Orsay (France); Schnell, BenoŅt; Petitjean, Laurent; Couty, Marc [Manufacture Franńaise des Pneumatiques MICHELIN, Centre de Ladoux, 23 place des Carmes, 63000 Clermont-Ferrand (France)] [Manufacture Franńaise des Pneumatiques MICHELIN, Centre de Ladoux, 23 place des Carmes, 63000 Clermont-Ferrand (France)
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.
Heat-pulse induced delayed phosphorescence (HIDP) of xanthone
NASA Astrophysics Data System (ADS)
Terada, Tomoyuki; Koyanagi, Motohiko; Kanda, Yoshiya
A heat-pulse modulation technique has been applied to the phosphorescence study of xanthone in n-pentane at 1.5 and 4.2 K. The heat-pulse induced delayed phosphorescence (HIDP) was observed via the internal and back-internal conversion processes among the phosphorescent levels. Decay properties were examined as a function of pulse-delay time.
Design, construction and Performance Evaluation of a Solar Water Pump
Abdulkadir Baba HASSAN; Muhammadu Masin MUHAMMADU
The study evaluated the performance of a solar water pump. The theoretical analysis on the performance evaluation of a solar water pump were made, the pump uses a low boiling point working fluid n- pentane. A flat plate solar generates vapour and its pressure is adequate to pump water. It shows that the pump can lift 2 litres (0.002m 3
Effect of Grinding Conditions on the Performance of a Selective Agglomeration Process for Physical Coal Cleaning
An extensive experimental study was conducted to investigate the effect of grinding conditions on the performance of a selective agglomeration process using n-pentane as agglomerant. Upper Freeport, Pittsburgh # 8, and Illinois # 6 coal samples were dry and wet ground to 28 mesh ū 0 and 200 mesh ū 0 particle sizes using a pulverizer, a ceramic jar mill,
TRANSITION BOILING HEAT TRANSFER FROM A HORIZONTAL SURFACE. Technical Report No. 17
An experiment, utilizing a condensing fluid as the heat source, was ; performed to determine the heat flux vs. temperature difference curve for ; transition pool boiling from a horizontal surface. The boiling curve was ; determined as a function of surface roughness, material, and cleanliness for n-; pentane at atmospheric pressure. The results of the experiment show that the
40 CFR Table 4 to Subpart Ppp of... - Known Organic HAP From Polyether Polyol Products
Code of Federal Regulations, 2010 CFR
...for Hazardous Air Pollutant Emissions for Polyether Polyols Production Pt. 63, Subpt. PPP, Table 4 Table 4 to Subpart PPP... Ethylene Oxide (75218) n-Hexane (110543) Methanol (67561) Propylene Oxide (75569) Toluene...
40 CFR Table 4 to Subpart Ppp of... - Known Organic HAP From Polyether Polyol Products
Code of Federal Regulations, 2011 CFR
...for Hazardous Air Pollutant Emissions for Polyether Polyols Production Pt. 63, Subpt. PPP, Table 4 Table 4 to Subpart PPP... Ethylene Oxide (75218) n-Hexane (110543) Methanol (67561) Propylene Oxide (75569) Toluene...
21 CFR 177.1320 - Ethylene-ethyl acrylate copolymers.
Code of Federal Regulations, 2010 CFR
...refluxing and subsequent cooling to 25 ░C. (ii) Maximum extractable fraction of 5.5 percent when extracted with n- hexane at 50 ░C. (d) The provisions of paragraphs (b) and (c)(2) of this section are not applicable to...
40 CFR Appendix: Table 1 to... - List of Hazardous Air Pollutants (HAP) for Subpart HHH
Code of Federal Regulations, 2010 CFR
...Carbonyl sulfide 100414 Ethyl benzene 107211 Ethylene glycol 75050 Acetaldehyde 50000 Formaldehyde 110543 n-Hexane 91203 Naphthalene 108883 Toluene 540841 2,2,4-Trimethylpentane 1330207 Xylenes (isomers and...
40 CFR 420.11 - Specialized definitions.
Code of Federal Regulations, 2010 CFR
...associated with steel production. (l) The term O&G (as HEM) means total recoverable oil and grease measured as n-hexane extractable material. (m) The term wet desulfurization system means those systems that remove sulfur compounds...
40 CFR Table 7 to Subpart Vvvvvv... - Partially Soluble HAP
Code of Federal Regulations, 2010 CFR
...67721 40. Methyl methacrylate 80626 41. Methyl-t-butyl ether 1634044 42. Methylene chloride 75092 43. N-hexane 110543 44. N,N-dimethylaniline 121697 45. Naphthalene 91203 46. Phosgene 75445 47. Propionaldehyde...
The accuracy of three passive dosimeters as compared to charcoal tubesĀ
Junco, Lynnea Goodley
to an American Industrial Hygiene Association (AIHA) accredited laboratory and analyzed for benzene, toluene, xylene, normal hexane (n-hexane), and total organic vapors (TOV). A statistical analysis of the reported data was conducted to determine if there were...
40 CFR Appendix: Table 1 to... - List of Hazardous Air Pollutants (HAP) for Subpart HHH
Code of Federal Regulations, 2012 CFR
...for Subpart HHH CAS Number a Chemical name 75070 Acetaldehyde 71432 Benzene (includes benzene in gasoline) 75150...100414 Ethyl benzene 107211 Ethylene glycol 75050 Acetaldehyde 50000 Formaldehyde 110543 n-Hexane 91203...
40 CFR Appendix: Table 1 to... - List of Hazardous Air Pollutants (HAP) for Subpart HHH
Code of Federal Regulations, 2013 CFR
...for Subpart HHH CAS Number a Chemical name 75070 Acetaldehyde 71432 Benzene (includes benzene in gasoline) 75150...100414 Ethyl benzene 107211 Ethylene glycol 75050 Acetaldehyde 50000 Formaldehyde 110543 n-Hexane 91203...
40 CFR Appendix: Table 1 to... - List of Hazardous Air Pollutants (HAP) for Subpart HHH
Code of Federal Regulations, 2011 CFR
...for Subpart HHH CAS Number a Chemical name 75070 Acetaldehyde 71432 Benzene (includes benzene in gasoline) 75150...100414 Ethyl benzene 107211 Ethylene glycol 75050 Acetaldehyde 50000 Formaldehyde 110543 n-Hexane 91203...
40 CFR Appendix: Table 1 to... - List of Hazardous Air Pollutants (HAP) for Subpart HHH
Code of Federal Regulations, 2014 CFR
...for Subpart HHH CAS Number a Chemical name 75070 Acetaldehyde 71432 Benzene (includes benzene in gasoline) 75150...100414 Ethyl benzene 107211 Ethylene glycol 75050 Acetaldehyde 50000 Formaldehyde 110543 n-Hexane 91203...
Improved extraction procedure for carotenoids from human milk.
Schweigert, F J; Hurtienne, A; Bathe, K
An improved method for the extraction of the major carotenoids from human milk is described. Carotenoids were extracted from milk first with ethanol and n-hexane. Then, polar xanthophylls were extracted from n-hexane into ethanol/water. The remaining n-hexane was evaporated, the residue combined with the ethanolic milk fraction and the mixture briefly saponified. Carotenoids were extracted from the hydrolysate with n-hexane, combined with the polar xanthophylls from the non-saponified ethanol/water-extract and separated by HPLC. Using this method we were able to significantly improve the recovery of xanthophylls such as lutein and zeaxanthin from human milk. The recovery rate of all carotenoids was > 90%. This method might not only be of value for milk but should be especially useful in the extraction of carotenoids from human tissues such as the adipose tissue. PMID:10883400
R. Moreira; A. Figueiredo; A. Sereno
Volumetric and thickness shrinkage evaluated by direct measurement and n-heptane displacement were determined during convective and freeze drying of Golden delicious apples. For convective drying, the influence of blanching and diameter\\/thickness ratio of the apple disks used were analysed at different levels of moisture content under constant conditions. It was found that shrinkage of dried samples, both by convection and
21 CFR 177.1830 - Styrene-methyl methacrylate copolymers.
Code of Federal Regulations, 2014 CFR
...extractives not to exceed an absorbance of 0.15. (3) Ultraviolet-absorbing distilled water and 8 and 50 percent alcohol...extractives not to exceed an absorbance of 0.30. (4) Ultraviolet-absorbing n- heptane extractives not to...
21 CFR 177.1830 - Styrene-methyl methacrylate copolymers.
Code of Federal Regulations, 2011 CFR
...extractives not to exceed an absorbance of 0.15. (3) Ultraviolet-absorbing distilled water and 8 and 50 percent alcohol...extractives not to exceed an absorbance of 0.30. (4) Ultraviolet-absorbing n- heptane extractives not to...
21 CFR 177.1830 - Styrene-methyl methacrylate copolymers.
Code of Federal Regulations, 2012 CFR
...extractives not to exceed an absorbance of 0.15. (3) Ultraviolet-absorbing distilled water and 8 and 50 percent alcohol...extractives not to exceed an absorbance of 0.30. (4) Ultraviolet-absorbing n- heptane extractives not to...
21 CFR 177.1830 - Styrene-methyl methacrylate copolymers.
Code of Federal Regulations, 2013 CFR
...extractives not to exceed an absorbance of 0.15. (3) Ultraviolet-absorbing distilled water and 8 and 50 percent alcohol...extractives not to exceed an absorbance of 0.30. (4) Ultraviolet-absorbing n- heptane extractives not to...
Interfacial activity of benzyloctadecyldimethyl ammonium chloride in a liquid\\/liquid extraction system
Guo Jin-xin; Cui Yu; Song Xin-yu; Li Xue-mei; Sun Xuan; Fan Wei-liu; Sun Guo-xin; Sun Si-xiu
Interfacial tension and interfacial adsorption parameters for benzyloctadecyldimethyl ammonium chloride (BODMAC) in three organic diluents were determined and interpreted. The interfacial activity of BODMAC is affected by the type of the organic diluent and the composition of the aqueous phase. The general order of interfacial activity of BODMAC is n-heptane (5% isobutanol) > carbon tetrachloride > chloroform. The effectiveness of
Using Nuclear Magnetic Resonance Spectroscopy for Measuring Ternary Phase Diagrams
ERIC Educational Resources Information Center
Woodworth, Jennifer K.; Terrance, Jacob C.; Hoffmann, Markus M.
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 undergraduateģ
Sub-millimeter sized methyl butanoate droplet combustion: Microgravity experiments
Walter, M.Todd
Sub-millimeter sized methyl butanoate droplet combustion: Microgravity experiments and detailed, spectrally resolved radiative heat transfer, multi-component diffusive transport, full thermal property compared with n-heptane droplets of nearly identical sizes over a range of oxygen concentrations
Lipase catalyzed formation of flavour esters
G. Langrand; C. Triantaphylides; J. Baratti
Summary Thirteen commercial lipase preparations were checked for their ability to catalyse the formation of flavour esters (isoamyl or geranyl acetate, propionate and butyrate) by either direct esterification or ester solvolysis in n-heptane. The formation of isoamyl or geranyl butyrates and propionates by direct esterification was catalyzed by the majority of the tested lipases. Acetic acid esters were more difficult
A new comprehensive semiempirical approach to calculate three-phase water/hydrocarbons equilibriaĀ
Tandia, Bagus Krisna
parameters, i.e. vapor phase composition (vi). In this study, the CSA has been used to run the data from Billman (1989) and Beladi (1995). These data include two ternary systems of n-heptane/n-dodecane/water, for which their initial overall compositions...
Second Virial Coefficients and the Forces Between Complex Molecules
J. O. Hirschfelder; F. T. McClure
The second virial coefficients of ethane, propane, n-butane, n-heptane, ammonia, methyl chloride, and the freons are computed from available experimental data. The causes for sizeable errors in second virial coefficients are considered. At temperatures above the critical, the second virial agrees with the theorem of corresponding states. Below the critical temperature, molecules with dipoles have unusually large virials and the
The effect of fatty acid concentration and water content on the production of biodiesel by lipase
Sulaiman Al-Zuhair; Kishnu Vaarma Jayaraman; Smita Krishnan; Wai-Hoong Chan
The kinetics of the production of biodiesel by esterification of butyric acid with methanol, catalysed by lipase from Mucor miehei, was studied in two types of systems, namely, n-hexane microaqueous and biphasic (n-hexane\\/water) containing different amounts of water. The experimental results were fit to a Ping-Pong mechanism and the constants found in the rate expression were determined. The results have
A Rapid Method for Hydrocarbon-type Analysis of Heavy Oils and Synthetic Fuels by Pyrolysis Thin Layer Chromatography
M. A. Poirier; A. E. George
Hydrocarbon-type fractions (saturates, aromatics, polynuclear aromatics, and polar compounds) from heavy crude oils and synthetic fuels were separated by thin layer chromatography (TLC) on chromarods, using an Iatroscan TH-10 analyzer. The best results were obtained on a silica gel chromarod when n-hexane, 10 percent benzene in n-hexane, and 5 percent ethyl acetate in benzene were used as developing solvent. A
A numerical model of perturbation gas chromatographyĀ
DeBarro, Marc Joseph
37 38 39 10. 12. 13. 14. 15. 16. 17. 18. Species Profile for a Positive Benzene Perturbation in System 1 Species Profile for a Positive Cyclohexane Perturbation in System 1 Species Profile for a Positive n-Hexane Perturbation in System... 1 Species Profile for a Cyclohexane Perturbation in System 3 Species Profile for a Positive n ? Hexane Perturbation in System 2 Species Profile for a Positive Benzene Perturbation in System 2 Species Profile for a Positive Cyclohexane...
Analysis of free and esterified sterols in vegetable oils
T. Verleyen; M. Forcades; R. Verhe; K. Dewettinck; A. Huyghebaert; W. De Greyt
In vegetable oils, phytosterols occur as free sterols or as steryl esters. Few analytical methods report the quantification\\u000a of esterified and free sterols in vegetable oils. In this study, esterified and free sterols were separated by silica gel\\u000a column chromatography upon elution with n-hexane\\/ethyl acetate (90?10 vol\\/vol) followed by n-hexane\\/diethyl ether\\/ethanol (25?25?50 by vol). Both fractions were saponified separately and
Antioxidant activity of Vitex agnus-castus L. extracts.
Sa?lam, H³sniye; Pabuńcuo?lu, Aysun; Kivńak, Bijen
The ethanol, n-hexane and water extracts of Vitex agnus-castus L. leaves and fruits were screened for antioxidant activity. The antioxidant activity of plant extracts was determined by an improved assay based on the decolorization of the radical monocation of 2,2'-azinobis-(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS.+). The water and ethanol extracts showed stronger antioxidant activity than the n-hexane extracts. PMID:17600861
Antioxidant activity of brown pigment and extracts from black sesame seed ( Sesamum indicum L.)
Juan Xu; Shubing Chen; Qiuhui Hu
The antioxidant activities of brown pigment, extract of n-hexane and extract of supercritical carbon dioxide extraction of black sesame seeds were investigated in this study. Kinetics of anti-radical activity showed that the reaction between DPPH and brown pigment of sesame seed was rapid and reached the steady state in 10 min. Extracts from supercritical carbon dioxide extraction and n-hexane extraction
Methods for determination of hexachlorobenzene and pentachlorophenol in soil samples
Luciana Polese; Maria L·cia Ribeiro
The efficiency of methods for the determination of hexachlorobenzene (HCB) and pentachlorophenol (PCP) in soil samples was evaluated. An on-line method was applied for HCB determination. Soil samples were transferred to chromatographic columns prepacked with alumina. The HCB elution was processed with n-hexane. The PCP was extracted from soil samples with n-hexane¢acetone in an ultrasonic bath. After re-extraction with K2CO3
Investigation of coal structure
Not Available
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.
Investigation of coal structure. Quarterly report, October 1, 1992--December 31, 1992
Not Available
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.
Branched vs. linear hydrocarbon separations with novel modified zeolites.
Gray, Gary R.; Noble, Richard D.; Nenoff, Tina Maria; Arruebo, Manuel; Ulutagay-Kartin, Mutlu; Anderson, Thomas M.
Conclusions of this paper are: (1) Adsorption/desorption on bulk unmodified zeolites showed isoprene adsorbed by zeolite-L and n-pentane adsorbed by zeolite-Y and ZSM-5; (2) Bulk carbonization is used to passivate zeolite activity toward organic adsorption/decomposition; (3) Based on the bulk modified zeolite separation results, we have determined that the MFI type has the most potential for isoprene enrichment; (4) Modified MFI type membranes are jointly made by Sandia and the Univ. of Colorado. Separation experiments are performed by Goodyear Chemical; (5) Isoprene/n-pentane separations have been demonstrated by using both zeolite membranes and modified bulk zeolites at various temperatures on the Goodyear Pilot-scale unit; and (6) Target zeolite membrane separations values of 6.7% isoprene enrichment have been established by economic analysis calculations by Burns & McDonnell.
Branched vs. linear hydrocarbon separations with novel modified zeolites.
Gray, Gary R.; Noble, Richard D.; Nenoff, Tina Maria; Arruebo, Manuel; Ulutagay-Kartin, Mutlu; Johnston, Kaylynn; Anderson, Thomas M.
The conclusions of this paper are: (1) Adsorption/desorption on bulk unmodified zeolites showed isoprene adsorbed by zeolite-L and n-pentane adsorbed by zeolite-Y and ZSM-5; (2) Bulk carbonization is used to passivate zeolite activity toward organic adsorption/decomposition; (3) Based on the bulk modified zeolite separation results, we have determined that the MFI type has the most potential for isoprene enrichment; (4) Modified MFI type membrane are jointly made by Sandia and the Univ. of Colorado. Separation experiments are performed by Goodyear Chemical; (5) Isoprene/n-pentane separations have been demonstrated by using both zeolite membranes and modified bulk zeolites at various temperatures on the Goodyear Pilot-scale unit; and (6) Target zeolite membrane separations values of 6.7% isoprene enrichment have been established by economic analysis calculations by Burns & McDonnell.
The Effect of the Addition of Re and Ge on the Properties of Pt\\/Al 2 O 3
M. C. Souza Santos; J. M. Grau; C. L. Pieck; J. M. Parera; J. L. G. Fierro; N. S. FĒgoli; M. C. Rangel
The effect of Re and Ge addition to Pt\\/Al2O3 was studied. Mono-, bi- and a trimetallic catalysts were prepared and characterized by TPR, XPS, TPO and by the n-pentane, cyclohexane (CH) and n-octane reactions. It was found that the trimetallic was the most active and stable catalyst and showed selectivities to aromatics and isomers very similar to the bimetallic germanium-based
Electron attachment to p-benzoquinone and photodetachment from benzoquinone anion in nonpolar solvents. [Pulse radiolysis followed by second pulse from tunable dye laser occurring after a delay of 10 to 200. mu. s
Although p-benzoquinone has a high electron affinity (1.9 eV), its reaction with excess electrons exhibits an unusual solvent and temperature dependence. The reaction is fast and has a positive activation energy in n-pentane but is much slower and has a negative activation energy in Si(CHŌ)Ō, neopentane, and 2,2,4,4-tetramethylpentane. The results can be explained in terms of an equilibrium with a
The effect of asphalt deposition on recovery of oil by a pentane slugĀ
Bhagia, Nanik S
as to style and content by: (Chairman o Commi ee) Member ommitte '(Member of Co 'ttee (Head of Department) May, I 965 TABLE OF CONTENTS Page ABSTRACT 2. INTRODUCTION 3. EXPERIMENTAL EQUIPMENT AND PROCEDURE . 4. PRESENTATION AND DISCUSSION OF RESULTS... precipitation. The miscible agents used in their study were Soltrol 430, a light naptha, and n( Pentane. These hydrocarbons precipitate much less asphalt than do propane and butane which are the mair. constituents of LPG. The volume of asphalt precipitated...
Thermo-economic optimization of waste heat recovery Organic Rankine Cycles
Sylvain Quoilin; Sķbastien Declaye; Bertrand F. Tchanche; Vincent Lemort
The present paper focuses both on the thermodynamic and on the economic optimization of a small scale ORC in waste heat recovery application. A sizing model of the ORC is proposed, capable of predicting the cycle performance with different working fluids and different components sizes. The working fluids considered are R245fa, R123, n-butane, n-pentane and R1234yf and Solkatherm. Results indicate
Isotope dilution determination of polycyclic aromatic hydrocarbons in olive pomace oil by gas chromatography¢mass spectrometry
Gianfranco Diletti; Giampiero Scortichini; Rossana Scarpone; Giuseppe Gatti; Luigi Torreti; Giacomo Migliorati
A gas chromatographic (GC) method with mass spectrometry detection (MS) for the determination of eight polycyclic aromatic hydrocarbons (PAHs) in olive pomace oil has been developed. The oil was diluted with n-pentane and extracted by liquid¢liquid partition with dimethyl sulphoxide (DMSO). After water addition and back-extraction with cyclohexane, a thin-layer chromatography on silica gel was performed as a further purification
Tricritical phenomena in ææquasibinaryÆÆ mixtures of hydrocarbons. I. Methane systems
Jefferson L. Creek; Charles M. Knobler; Robert L. Scott
Temperature, pressure, and composition measurements are reported for the three coexisting phases in the region of the tricritical points of two ternary mixtures of hydrocarbons: methane+n-pentane+2,3-dimethylbutane (I) and methane+2,2-dimethylbutane+2,3-dimethylbutane (II). These systems satisfy a ÆÆquasibinaryÆÆ approximation in which the proportions of the two higher hydrocarbons [expressed as Z = xC\\/(xB+xC)] are the same in each of the three phases, so
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
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.
Comparison of Eluents in Supercritical Fluid Chromatography
Dietger Leyendecker; Dagmar Leyendecker; Franz P. Schmitz; Ernst Klesper
The chromatographic behavior of a number of low boiling eluents has been compared in supercritical fluid chromatography (SFC) with packed columns. Unmodified silica gel has been used as the stationary phase and a test mixture of polycyclic aromatic hydrocarbons (PAH's) as the substrate. Carbon dioxide, nitrous oxide, trifluoromethane, chlorotrifluoromethane, n-pentane, n-butane, i-butane, propane, ethane, diethylether, and dimethylether have been investigated
Saturated pool and flow boiling from horizontal cylinders
A study of pool and flow boiling from heated horizontal cylinders at atmospheric pressure is presented. Pool boiling heat flux vs. wall superheat boiling curves were obtained for 3.18-mm brass tubes heated by an internal flow of ethylene glycol. These curves were obtained in saturated Freon-113, n-pentane, acetone, benzene, ethanol, methanol, and isopropanol. Temperature limitations prevented operation in the film-boiling
Adsorption of C5¢C9 hydrocarbons in microporous MOFs MIL100(Cr) and MIL101(Cr): A manometric study
Thuy Khuong Trung; Naseem A. Ramsahye; Philippe Trens; Nathalie Tanchoux; Christian Serre; Franńois Fajula; Gķrard Fķrey
The adsorption of n-alkanes (n-pentane to n-nonane) on the mesoporous MIL-100(Cr) and the MIL-101(Cr) rigid solids has been performed with a view of evaluating the influence of the alkyl chain length in terms of sorption capacity and sorbate\\/sorbent affinity. MIL-100(Cr) exhibits at first sight a classical type I behaviour towards the sorption of n-alkanes. These sorption isotherms have proven to
Investigation and technique in the fluorescent spectra examination of crude oilĀ
Chambers, Gilbert Vester
sediments (25, 28) and source rock (12, 15) by columnar chromatography. Kerr, Weatherford and 'apell (16) chromatographed undiluted virgin crude petroleum oils on alumina. The developers used were n-pentane, thKophene-free benzene, and 25 volume percent... absolute methanol in thiophene-free benzene. They reported that the first appearance of sulfur compounds in the pentane eluant corresponds closely to the initial appearance of compounds which fluoresce visibly in a ultra violet light. Hunt (11) used...
A biomass-fired micro-scale CHP system with organic Rankine cycle (ORC) ¢ Thermodynamic modelling studies
Hao Liu; Yingjuan Shao; Jinxing Li
This paper presents the results of thermodynamics modelling studies of a 2ĀkW (e) biomass-fired CHP system with organic Rankine cycle (ORC). Three environmentally friendly refrigerants, namely HFE7000, HFE7100 and n-pentane, have been selected as the ORC fluids. The thermodynamic properties of the selected ORC fluids which have been predicted by commercial software (EES) are used to predict the thermal efficiency
Development of a prototype low-temperature Rankine cycle electricity generation system
V. M. Nguyen; P. S. Doherty; S. B. Riffat
This paper describes the development of a small-scale system designed to generate electricity from low temperature heat (e.g., solar energy). The system operates on the Rankine cycle and uses n-pentane as the working fluid. A prototype system has been designed, constructed and tested. It is capable of delivering 1.5 kW of electricity with a thermal efficiency of 4.3%. Laboratory test
Hydroconversion of heavier n-paraffins with Pt\\/ZrO sub 2 \\/SO sub 4 sup 2 minus
M. Y. Wen; J. Kundurmutt; J. W. Tierney; I. Wender
The development of effective solid acid catalysts has gained great interest in the refining and petrochemical industries for the last two decades, mainly due to the advantages of less corrosivity, fewer environmental problems, and easy separation from reaction mixtures of these solid acids. Recently, Pt\\/ZrOŌ\\/SOŌ┬▓Ōü╗, a solid superacid, was reported to be active for the hydroisomerization of n-pentane and desulfurized
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.
Computational study of hydrocarbon adsorption in metal-organic framework Ni2(dhtp).
Sun, Xiuquan; Wick, Collin D; Thallapally, Praveen K; McGrail, B Peter; Dang, Liem X
Enhancing the efficiency of the Rankine cycle, which is utilized for multiple renewable energy sources, requires the use of a working fluid with a high latent heat of vaporization. To further enhance its latent heat, a working fluid can be placed in a metal organic heat carrier (MOHC) with a high heat of adsorption. One such material is Ni\\DOBDC, in which linear alkanes have a higher heat of adsorption than cyclic alkanes. We carried out molecular dynamics simulations to investigate the structural, diffusive, and adsorption properties of n-hexane and cyclohexane in Ni\\DOBDC. The strong binding for both n-hexane and cyclohexane with Ni\\DOBDC is attributed to the increase of the heat of adsorption observed in experiments. Our structural results indicate the organic linkers in Ni\\DOBDC are the primary binding sites for both n-hexane and cyclohexane molecules. However, at all temperatures and loadings examined in present work, n-hexane clearly showed stronger binding with Ni\\DOBDC than cyclohexane. This was found to be the result of the ability of n-hexane to reconfigure its structure to a greater degree than cyclohexane to gain more contacts between adsorbates and adsorbents. The geometry and flexibility of guest molecules were also related to their diffusivity in Ni\\DOBDC, with higher diffusion for flexible molecules. Because of the large pore sizes in Ni\\DOBDC, energetic effects were the dominant force for alkane adsorption and selectivity. PMID:21384829
Upgrading light hydrocarbons via tandem catalysis: a dual homogeneous Ta/Ir system for alkane/alkene coupling.
Leitch, David C; Lam, Yan Choi; Labinger, Jay A; Bercaw, John E
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
Possible room temperature superconductivity in conductors obtained by bringing alkanes into contact with a graphite surface
NASA Astrophysics Data System (ADS)
Kawashima, Yasushi
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.
Possible room temperature superconductivity in conductors obtained by bringing alkanes into contact with a graphite surface
Kawashima, Yasushi
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
Calibration of a Harwood DWT-1000 controlled-clearance piston gauge
NASA Astrophysics Data System (ADS)
Shain, D. I.; Deitesfeld, C. A.
To meet growing demands for higher pressure measurements and measurement accuracies up to 200,000 psig, the Physical Metrology Laboratory (PML) at Rocky Flats Plant, Golden, Colorado, purchased and calibrated a Harwood Model DWT-1000, controlled-clearance piston gauge. Calibration of the DWT-1000 followed guidelines established by the National Bureau of Standards (NBS). The pressure medium used during operation and calibration of the system was n-Heptane. Due to the flammability of n-Heptane, safety enclosure was designed and constructed around the DWT-1000 which, when used in conjunction with a data acquisition console, monitors both safety and calibration equipment while protecting the surrounding environment in the event of a sudden pressure release. Calibration results and procedures are compiled in this report to assist those who will be or are presently confronted with the challenge of calibrating a similar type controlled-clearance piston gauge.
Two-dimensional simulations of droplet evaporation and deformation at high pressure
Zheng-Tao Deng; Ron Litchford; Shenghun Jeng; San-Mou Jeng
A two-dimensional analysis of n-Heptane droplet vaporization in a high-pressure nitrogen gas is made with special attention devoted to droplet deformation and breakup. The considered theoretical model can solve two-phase fluid flows separated by a material interface where surface tension forces and interfacial heat, mass, and momentum exchanges exist. The computational model, which includes free-surface (droplet surface) tracking and complex
Hydrocarbon fuel cooling technologies for advanced propulsion
D. R. Sobel; L. J. Spadaccini
Storable hydrocarbon fuels that undergo endothermic reaction provide an attractive heat sink for future high-speed aircraft. An investigation was conducted to explore the endothermic potential of practical fuels, with inexpensive and readily available catalysts, under operating conditions simulative of high-speed flight applications. High heat sink capacities and desirable reaction products have been demonstrated for n-heptane and Norpar 12 fuels using
Metabolite profiling and assessment of metabolome compartmentation of soybean leaves using non-aqueous fractionation and GC-MS analysis
Noureddine Benkeblia; Takuro Shinano; Mitsuru Osaki
In the present study, non-aqueous fractionation (NAQF) and GC-MS were used to obtain a spatially resolved view of metabolism\\u000a in mature leaves of soybean (Glycine\\u000a max Merr.). NAQF of lyophilized soybean leaves was performed using CCl4-n-heptane and ultracentrifugation that yielded a gradient comprised of six fractions. Chlorophyll content, and marker enzyme\\u000a activities, phosphoenolpyruvate carboxylase (PEPC) and ?-mannosidase, were utilized as
Extraction Kinetics of Rare Earth Metals with 2-Ethylhexyl Phosphonic Acid Mono2-ethylhexyl Ester Using a Hollow Fiber Membrane Extractor
Fukiko Kubota; Masahiro Goto; Fumiyuki Nakashio; Tadashi Hano
A kinetic study concerning chemical complexation-based solvent extraction of rare earth metals with 2-ethylhexyl phosphonic acid mono-2-ethylhexyl ester dissolved as an extractant in n-heptane was carried out using a microporous hydrophobic hollow fiber membrane extractor. The effects of concentration of chemical species in aqueous and organic feed solutions on the apparent permeabilities of metal species for extraction and stripping, respectively,
Fukiko Kubota; Masahiro Goto; Fumiyuki Nakashio
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)2, as follows.The extraction equilibrium constants of metals were obtained and compared with the extraction equilibrium constants
Isolation of strontium-90, yttrium-90, promethium-147, and cerium-144 from wet ashed urine by calcium oxalate coprecipitation and sequential solvent extraction
Gary H. Kramer; Janet M. Davies
A method has been developed for separating low-level activities of the ..beta..-emitting isotopes strontium-90, yttrium-90, promethium-147, and cerium-144 from urine and aqueous solutions. They are subsequently estimated by direct counting of sources on planchets or by liquid scintillation counting. The radionuclides are separated from each other and from interfering elements by solvent extraction with HDEHP (di-2-ethylhexyl)phosphoric acid) in n-heptane. It
Laser-induced spark ignition has proved to be an alternative way of achieving ignition. In this paper, we demonstrate the feasibility of laser spark ignition at the outlet of a lean premixed prevaporized injector, similar to those used in low-NOx air jet engines. This injector uses liquid n-heptane as fuel in preheated air with a high level of turbulence. After a
Description and prediction of retention in normal-phase high-performance liquid chromatography with binary and ternary mobile phases
P. Jandera; M. Ku?erovß; J. HolĒkovß
The suitabilities of several earlier reported models for description and prediction of retention in normal-phase systems with mobile phases comprised of two organic solvents Ś a polar and a non-polar one Ś were tested on the chromatographic behaviour of phenylurea herbicides and alkyl-, aryl- and nitrophenols as sample solutes with a silica-gel column and 2-propanol, n-heptane and dioxane as mobile
Solvent extraction study of rare earth elements from chloride medium by mixtures of sec-nonylphenoxy acetic acid with Cyanex301 or Cyanex302
Shanshan Tong; Xiaowei Zhao; Naizhong Song; Qiong Jia; Weihong Zhou; Wuping Liao
The extraction of rare earth elements from chloride medium by mixtures of sec-nonylphenoxy acetic acid (CA100) with bis(2,4,4-trimethylpentyl) dithiophosphinic acid (Cyanex301) or bis(2,4,4-trimethylpentyl) monothiophosphinic acid (Cyanex302) in n-heptane has been studied. The synergistic enhancement of the extraction of lanthanum (III) by mixtures of CA100 with Cyanex301 has been investigated using the methods of slope analysis and constant mole. The extracted
Evaluation of hepatoprotective activity of Cassia fistula leaf extract
T. Bhakta; Pulok K. Mukherjee; Kakali Mukherjee; S. Banerjee; Subhash C. Mandal; Tapan K. Maity; M. Pal; B. P. Saha
Hepatoprotective activity of the n-heptane extract of Cassia fistula leaves was investigated in rats by inducing hepatotoxicity with carbon tetrachloride:liquid paraffin (1:1). The extract has been shown to possess significant protective effect by lowering the serum levels of transminases (SGOT and SGPT), bilirubin and alkaline phosphatase (ALP). The extract of C. fistula at a dose of 400 mg\\/kg showed significant
Self-ignition of S.I. engine model fuels: A shock tube investigation at high pressure
K. Fieweger; R. Blumenthal; G. Adomeit
The self-ignition of several spark-ignition (SI) engine fuels (iso-octane, methanol, methyl tert-butyl ether and three different mixtures of iso-octane and n-heptane), mixed with air, was investigated experimentally under relevant engine conditions by the shock tube technique. Typical modes of the self-ignition process were registered cinematographically. For temperatures relevant to piston engine combustion, the self-ignition process always starts as an inhomogeneous,
Conversion and hydroconversion of hydrocarbons on zeolite-based catalysts: an FT-IR study
Marcella Trombetta; Tiziana Armaroli; Horacio Gonzalez; Jorge Ramirez Solis; Guido Busca
The interaction of HZSM5 and Mo-ZSM5 with benzene, naphthalene, toluene, ortho-xylene, para-xylene, n-butane, isobutane, n-heptane, and methylcyclohexane, in the range 100¢773K has been investigated using FT-IR spectroscopy. Hydrogen bonded species with the internal bridging and the external terminal OHs has been detected. The reactivity at high temperature has also been studied. The access to the internal cavities and to the
Hydroconversion of model mixtures of FCC gasoline over metal¢zeolite catalysts. Reaction study and mathematical modelling
Erik Ocaranza; Horacio Gonzßlez; Jorge RamĒrez
The hydroconversion of a n-heptane¢methylcyclohexane¢toluene mixture representative of FCC gasoline was analyzed through a lumped parameter reaction model that incorporates the main reaction paths and the acid\\/metal sites ratio of the catalyst as an explicit key parameter. The catalytic experiments were performed at relevant operating conditions using mechanical mixtures of metal\\/alumina+HZSM5 powders. The catalyst acid\\/metal sites ratio was modified by
Simultaneous Determination of Nalbuphine and Opiates in Human Hair by Gas Chromatography-Mass Spectrometry
Jin Young Kim; Moon Kyo In; Ki-Jung Paeng; Bong Chul Chung
The method for simultaneous determination of nalbuphine and opiates (codeine, morphine, and 6-monoacetylmorphine) in human hair was developed in the selected-ion monitoring (SIM) mode of a gas chromatography-mass spectrometer (GC-MS). Thirty-milligram hair samples were incubated in 0.01 M HCl overnight at 50 ░C. We extracted the drugs from resulting hydrolyzed solutions with a mixture of chloroform-isopropanol- n-heptane (50:17:33, v\\/ v\\/
Photoionization of Alkanes. Dissociation of Excited Molecular Ions
Bruce Steiner; Clayton F. Giese; Mark G. Inghram
This report describes studies of photoionization and subsequent dissociation of all saturated paraffins from C2 to C6, plus n-heptane and n-octane, as a function of photon energy. The studies include data on all processes which occur below a photon energy of 11.9 ev. The instrument used was a mass spectrometer, combined with a Seya-Namioka monochromator. The direct experimental data are
DESTRUCTION OF VOCs IN A NON-THERMAL PLASMA REACTOR
C. Christodoulatos; K. Becker; P. J. Ricatto; G. P. Korfiatis; E. E. Kunhardt
The work presented herein investigates the effectiveness and efficiency of a novel, non-thermal large-volume ambient pressure diffuse plasma for destruction of environmental air contaminants. The plasma characteristics, plasma chemistry, and contaminant destruction efficiency for selected contaminants including benzene, toluene, n-heptane, iso-octane, and methanol were investigated. Plasma spectroscopic studies employing gas mixtures of He with N2 of 1-20% yielded electron temperatures
Thermostable NADP+Dependent Medium-Chain Alcohol Dehydrogenase from Acinetobacter sp. Strain M-1: Purification and Characterization and Gene Expression in Escherichia coli
NADPH-dependent alkylaldehyde reducing enzyme, which was greatly induced by n-hexadecane, from Acin- etobacter sp. strain M-1 was purified and characterized. The purified enzyme had molecular masses of 40 kDa as determined by sodium dodecyl sulfate-polyacrylamide gel electrophoresis and 160 kDa as determined by gel filtration chromatography. The enzyme, which was shown to be highly thermostable, was most active toward n-heptanal
Cracking Behavior of Zeolites with Connected 12- and 10Member Ring Channels: The Influence of Pore Structure on Product Distribution
A. Corma; M. Davis; V. Fornķs; V. Gonzßlez-Alfaro; R. Lobo; A. V. Orchillķs
n-Heptane has been cracked on a CIT-1 zeolite which has connected 12- and 10-member ring (MR) channels, and its behavior was compared with that of MCM-22 with nonconnected 12- and 10-MR channels, and SSZ-24 and BETA with unidirectional and tridirectional 12-MR channels, respectively. The kinetic rate constant is highest for CIT-1, and the decay constant is lowest. From the selectivity
Numerical modeling of isolated n-alkane droplet flames: initial comparisons with ground and space-based microgravity experiments
Anthony J. Marchese; Frederick L. Dryer; Vedha Nayagam
Transient, spherically symmetric, combustion of single and multi-component liquid n-alkane droplets is numerically simulated with a model that includes gas phase detailed, multi-component molecular transport and complex chemical kinetics. A compact semi-detailed kinetic mechanism for n-heptane and n-hexadecane oxidation consisting of 51 species (including He, Ar, and N2) and 282 reactions is used to describe the gas phase. Non-luminous, gas
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
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.
Autothermal reforming of simulated gasoline and diesel fuels
R. K. Kaila; A. O. I. Krause
Autothermal reforming (ATR) of simulated fuels was studied with n-heptane, n-dodecane, toluene, and methylcyclohexane as model compounds for different fractions of gasoline and diesel on zirconia-supported Rh and Pt. A performance comparison was made on commercial nickel catalyst. No inhibiting effect was observed between the hydrocarbons on any catalyst, even though aliphatic hydrocarbons are more reactive than aromatics. The product
Evaluation of hepatoprotective activity of Cassia fistula leaf extract.
Bhakta, T; Mukherjee, P K; Mukherjee, K; Banerjee, S; Mandal, S C; Maity, T K; Pal, M; Saha, B P
Hepatoprotective activity of the n-heptane extract of Cassia fistula leaves was investigated in rats by inducing hepatotoxicity with carbon tetrachloride:liquid paraffin (1:1). The extract has been shown to possess significant protective effect by lowering the serum levels of transminases (SGOT and SGPT), bilirubin and alkaline phosphatase (ALP). The extract of C. fistula at a dose of 400 mg/kg showed significant hepatoprotective activity which was comparable to that of a standard hepatoprotective agent. PMID:10473173
Hepatoprotective activity of Cassia fistula leaf extract.
Bhakta, T; Banerjee, S; Mandal, S C; Maity, T K; Saha, B P; Pal, M
Hepatoprotective activity of the n-heptane extract of Cassia fistula leaves was investigated by inducing hepatotoxicity with paracetamol in rats. The extract at a dose of 400 mg/kg body wt. exhibited orally, significant protective effect by lowering the serum levels of transaminases (SGOT and SGPT), bilirubin and alkaline phosphatase (ALP). The effects produced were comparable to that of a standard hepatoprotective agent. PMID:11417916
Speciated Hydrocarbon Emissions from the Combustion of Single Component Fuels. I. Effect of Fuel Structure
W. O. Siegel; R. W. McCabe; W. Chun; E. W. Kaiser; J. Perry; Y. I. Henig; F. H. Trinker; R. W. Anderson
Speciated hydrocarbon emissions data have been collected for six single-component fuels run in a laboratory pulse flame combustor (PFC). The six fuels include n-heptane, isooctane (2, 2, 4-trimethylpentane), cyclohexane, 1-hexene, toluene, and methyl-t-butyl ether (MTBE: an oxygenated fuel extender). Combustion of non-aromatic fuels in the PFC (at a fuel\\/air equivalence ratio of ? = 1.02) produced low levels of unburned
Transition from cool flame to thermal flame in compression ignition process
Yamada, Hiroyuki; Suzaki, Kotaro; Goto, Yuichi [National Traffic Safety and Environment Laboratory, 7-42-27 Jindaiji-Higashimachi, Chofu, Tokyo 182-0012 (Japan); Tezaki, Atsumu [Department of Mechanical and Intellectual Systems Engineering, University of Toyama, Gofuku 3190, Toyama-shi, Toyama 930-8555 (Japan)
The mechanism that initiates thermal flames in compression ignition has been studied. Experimentally, a homogeneous charge compression ignition (HCCI) engine was used with DME, n-heptane, and n-decane. Arrhenius plots of the heat release rate in the HCCI experiments showed that rates of heat release with DME, n-heptane, and n-decane exhibited a certain activation energy that is identical to that of the H{sub 2}O{sub 2} decomposition reaction. The same feature was observed in diesel engine operation using ordinary diesel fuel with advanced ignition timing to make ignition occur after the end of fuel injection. These experimental results were reproduced in nondimensional simulations using kinetic mechanisms for DME, n-heptane, and n-decane, the last being developed by extending the n-heptane mechanism. Methanol addition, which suppresses low-temperature oxidation (LTO) and delays the ignition timing, had no effect on the activation energy obtained from the Arrhenius plot of heat release rate. Nevertheless, methanol addition lowered the heat release rates during the prethermal flame process. This is because H{sub 2}O{sub 2} formation during cool flame was reduced by adding methanol. The mechanism during the transition process from cool flame to thermal flame can be explained quantitatively using thermal explosion theory, in which the rate-determining reaction is H{sub 2}O{sub 2} decomposition, assuming that heat release in this period is caused by partial oxidation of DME and HCHO initiated with the reaction with OH produced though H{sub 2}O{sub 2} decomposition. (author)
Complex formation between chlorine dioxide and 2,2,6,6-tetramethylpiperidin-1-oxyl
I. M. Ganiev; V. V. Shereshovets; I. A. Grigor'ev; G. A. Tolstikov
The complex formation of ClO2 with 2,2,6,6-tetramethylpiperidin-1-oxyl (TMPO) in acetone, acetonitrile,n-heptane, diethyl ether, carbon tetrachloride, and toluene was studied spectrophotometrically at ?20 to +20 C. The thermodynamic\\u000a parameters of complex formation were determined at 20 C. The transformation of the complex into the oxoammonium salt TMPO+ClO\\u000a 2\\u000a ?\\u000a was found.
Synthesis and catalytic properties of microemulsion-derived cerium oxide nanoparticles
Emanuel Kockrick; Christian Schrage; Anett Grigas; Dorin Geiger; Stefan Kaskel
The synthesis of cerium dioxide nanoparticles using an inverse microemulsion technique and precipitation method was investigated. Cerium hydroxide nanoparticles were synthesized by adding diluted ammonia to n-heptane¢surfactant¢cerium nitrate system. The micelle and particle size in the range of 5¢12nm were controlled by varying the molar water to surfactant ratio and analyzed by dynamic light scattering (DLS), small angle X-ray scattering
C╔LINE MORIN; CHRISTIAN CHAUVEAU; PHILIPPE DAGAUT; ISKENDER GųKALP; MICHEL CATHONNET
Vaporization and oxidation of liquid fuel droplets are basic mechanisms in spray combustion for various industrial applications. In this work, coupled effects of temperature and pressure on n-alkane droplet vaporization are investigated in experiments conducted in a high-pressure and high-temperature gasification facility equipped with the fiber-suspended droplet technique. The influence of temperature and pressure on n-heptane and n-decane vaporization rates
Low severity upgrading of FT waxes with solid superacids. Quarterly report, March 1, 1994May 31, 1994
J. W. Tierney; I. Wender
In this quarter the authors studied the isomerization and hydrocracking of paraffins in the presence of aromatics and naphthenes. It was found that one could alkylate aromatics and naphthenes with paraffins over a Pt\\/ZrOŌ\\/SOŌ catalyst at 160┬░C and 350 psig of HŌ (380-420 psig during the reaction). Surprisingly, 75 wt% of cyclohexane was alkylated by alkyl groups derived from n-heptane
Allelopathic potential of Artemisia arborescens: isolation, identification and quantification of phytotoxic compounds through fractionation-guided bioassays.
Araniti, Fabrizio; Lupini, Antonio; SorgonÓ, Agostino; Conforti, Filomena; Marrelli, Mariangela; Statti, Giancarlo Antonio; Menichini, Francesco; Abenavoli, Maria Rosa
The aerial part of Artemisia arborescens L. (Asteraceae) was extracted with water and methanol, and both extracts were fractionated using n-hexane, chloroform, ethyl acetate and n-butanol. The potential phytotoxicity of both crude extracts and their fractions were assayed in vitro on seed germination and root growth of lettuce (Lactuca sativa L.), a sensitive species largely employed in the allelopathy studies. The inhibitory activities were analysed by dose-response curves and the ED 50 were estimated. Crude extracts strongly inhibited both germination and root growth processes. The fraction-bioassay indicated the following hierarchy of phytotoxicity for both physiological processes: ethyl acetate ? n-hexane > chloroform ? n-butanol. On the n-hexane fraction, GC-MS analyses were carried out to characterise and quantify some of the potential allelochemicals. Twenty-one compounds were identified and three of them, camphor, trans-caryophyllene and pulegone were quantified. PMID:22687059
Observations of soot during droplet combustion at low gravity - Heptane and heptane/monochloroalkane mixtures
NASA Technical Reports Server (NTRS)
Jackson, G. S.; Avedisian, C. T.; Yang, J. C.
Experimental observations of the combustion of sooting fuel droplets, performed in a drop tower to create a low gravity environment, are reported. Free n-heptane droplets and suspended droplets of heptane, monochloroalkanes, and mixtures of monochloro-octane and heptane were studied. Initial droplet diameters ranged from 0.4 to 1.1. mm. The results suggest that soot may influence droplet vaporization rates. Spherical symmetry of the flame allowed for extended observation of soot agglomerates inside the droplet flame. Effects of slight convective flows were also observed, both through variations of natural convection around the suspended droplets and through variations in the drift velocities of the unsupported droplets. Slight convective flows around the suspended droplets reduced flame luminosity as well as soot accumulation inside the flame and increased droplet vaporization rates. Mixing monochloro-octane with n-heptane demonstrated the effectiveness of n-heptane in reducing soot emissions from the flames of the chlorinated fuels. Finally, trends of initial droplet diameter with burning rate were observed and may be linked to the effect of droplet size upon soot formation inside the flame.
Structural and phase transformations during ball milling of titanium in medium of liquid hydrocarbons
NASA Astrophysics Data System (ADS)
Dorofeev, G. A.; Lubnin, A. N.; Lad'yanov, V. I.; Mukhgalin, V. V.; Puskkarev, B. E.
It has been shown using X-ray diffraction, scanning electron microscopy, and chemical analysis that, upon ball milling of ?-titanium in liquid organic media (toluene and n-heptane), a nanocrystalline fcc phase is formed that is a metastable carbohydride Ti(C,H) deficient in hydrogen and carbon compared to stable carbohydrides. The dimensions of powder particles after milling in toluene and n-heptane differ substantially (are 5-10 and 20-30 ?m, respectively. It has been shown that the kinetics of the formation of Ti(C,H) is independent of the milling medium. The atomic ratios H/C in the products of mechanosynthesis agree well with those corresponding to the employed organic media, i.e., H/C = 1.1 for toluene and 2.3 for n-heptane. A solid-liquid mechanism of mechanosynthesis is suggested, which includes repeated processes of particle fracturing with the formation of fresh surfaces, adsorption of liquid hydrocarbons on these surfaces, and subsequent cold welding of the newly formed particles. It is assumed that the formation of the fcc phase in the process of milling is connected with the generation of stacking faults in ?-Ti. Upon annealing at 550░C, the fcc phase decomposes with the formation of stable titanium carbide TiC (annealing in a vacuum) or stable titanium carbohydride and a ?-Ti(H) solid solution (annealing in argon) with a partial reverse transformation Ti(C,H) ? ?-Ti in both cases.
Simple solvothermal synthesis of hydrophobic magnetic monodispersed Fe{sub 3}O{sub 4} nanoparticles
Liu, Jing; Wang, Lu [School of Pharmaceutical Sciences, Hebei Medical University, Shijiazhuang 050017 (China)] [School of Pharmaceutical Sciences, Hebei Medical University, Shijiazhuang 050017 (China); Wang, Jing, E-mail: firstname.lastname@example.com [School of Pharmaceutical Sciences, Hebei Medical University, Shijiazhuang 050017 (China)] [School of Pharmaceutical Sciences, Hebei Medical University, Shijiazhuang 050017 (China); Zhang, Lantong, E-mail: email@example.com [School of Pharmaceutical Sciences, Hebei Medical University, Shijiazhuang 050017 (China)] [School of Pharmaceutical Sciences, Hebei Medical University, Shijiazhuang 050017 (China)
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.
HPLC determination of flumethrin, deltamethrin, cypermethrin, and cyhalothrin residues in the milk and blood of lactating dairy cows.
Bissacot, D Z; Vassilieff, I
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
Rotational Isomers, Intramolecular Hydrogen Bond, and IR Spectra of o-Vinylphenol
NASA Astrophysics Data System (ADS)
Glazunov, V. P.; Berdyshev, D. V.; Balaneva, N. N.; Radchenko, O. S.; Novikov, V. L.
Absorption bands of OH stretching vibrations in IR spectra of o-vinylphenol ( o-VP) in the weakly polar solvents CCl4 and n-hexane were studied. Several rotamers of the free OH group were observed for o-VP in n-hexane. The fraction of o-VP rotamers with an O-Hģ? intramolecular hydrogen bond (IHB) was less than 20% according to experimental estimates for CCl4 solutions and calculations in the gas phase and cyclohexane. The theoretical effective enthalpy of the o-VP IHB was estimated for rotamer A (-?H = 0.20 kcal/mol).
The oxidation of a gasoline surrogate in the negative temperature coefficient region
Lenhert, David B.; Miller, David L.; Cernansky, Nicholas P. [Department of Mechanical Engineering and Mechanics, Drexel University, 3141 Chestnut Street, Philadelphia, PA 19104-2875 (United States); Owens, Kevin G. [Department of Chemistry, Drexel University, 3141 Chestnut Street, Philadelphia, PA 19104-2875 (United States)
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)
Solvothermal Synthesis and Supported Catalysis of Polyanion-derived Metal Oxide Nanoparticles
NASA Astrophysics Data System (ADS)
Soultanidis, Nikolaos
Supported metal oxides (SMOs) are important catalytic materials that find numerous applications in important industrial processes. Improving the structural properties of SMOs is a challenging objective due to material synthesis and characterization limitations. Recent developments in the characterization of SMOs, specifically tungstated zirconia (WOx/ZrO2), have revealed structural information that renewed scientific interest in developing more sophisticated synthetic protocols for SMOs. The current work aims to provide a robust characterization of WO x/ZrO2 by using different characterization techniques and probe reactions. Conventional and non-conventional synthetic methods are investigated to cover the whole spectrum of published methods in order to understand the properties and limitations of these techniques. In the second part of this work, a new synthetic approach is presented that successfully produces ultrasmall (smaller than 2 nm) tungsten oxide nanoparticles (WOx NPs). By using conventional tungsten precursors and oleylamine, WOx NPs are synthesized, characterized, and finally supported to test their propene metathesis activity. Conventional WOx/ZrO2 catalysts were prepared and extensively studied by probing their n-pentane isomerization activity and methanol dehydration activity. WOx/ZrO2 prepared via incipient wetness impregnation shows maximum n-pentane isomerization turnover rates (TOR) at intermediate surface densities (rhosurf). This method delivers the most active n-pentane isomerization WOx/ZrO 2 catalysts since it maximizes the number density of the active sub-nm slightly distorted Zr-WOx sites at rhosurf between 5.2-6.2 W/nm2. By comparing the n-pentane isomerization activity with the methanol dehydration activity of WOx /ZrO2, n-pentane isomerization is shown to be an excellent probe reaction for qualitatively identifying the relative (to the other species) population density of Zr-WOx clusters. Bimolecular n-pentane isomerization is the prevailing mechanism and requires a higher population density of Zr-WOx clusters than methanol dehydration. In the second part of this work, a new solvothermal synthesis route for the preparation of ultrasmall tungsten oxide nanoparticles (WOx NPs) is introduced. By using ammonium polyanionic salts and oleylamine, high yields (92+/-5%) of oleylaminecoated WOx NPs were consistently synthesized. The co-addition of an organic oxidant during the synthesis led to smaller WOx NPs thereby providing insight into the NP synthesis mechanism. Deposition and activation of the NPs on SiO2 support by removal of oleylamine allows better control over the WOx domain size than conventional methods. Oleylamine suppresses WOx NP sintering during calcination and prevents the formation of larger polytungstates present in conventional catalysts. The supported WOx NPs were found to be up to 3 times more selective for metathesis products than conventionally prepared tungstated silica likely due to their controlled structure.
Combining solvent engineering and thermodynamic modeling to enhance selectivity during monoglyceride synthesis by lipase-catalyzed esterification.
Bellot, J C.; Choisnard, L; Castillo, E; Marty, A
Monoglyceride synthesis by Rhyzomucor miehei lipase was investigated via direct esterification between glycerol (adsorbed onto silica gel) and oleic acid in organic solvents. The main difficulty is to avoid the unwanted production of di- and tri-glycerides. It was demonstrated that an increase in solvent polarity, using mixtures of n-hexane and 2-methyl-2-butanol (2M2B), improves drastically the selectivity toward monoglyceride formation. In pure n-hexane, the monoglyceride represents only 6 molar % of the total products at the thermodynamic equilibrium (34 and 60% for di- and tri-glyceride respectively). Use of an equivolume mixture of n-hexane/2M2B enables a product mixture to be obtained containing 94% of monoglyceride at equilibrium (2.4 and 0% for di- and tri-glyceride respectively). This positive effect is counterbalanced by a decrease both in initial velocities and in substrate conversion at thermodynamic equilibrium.A modeling, able to predict the three thermodynamic equilibria governing the 3 consecutive reactions, based on activity coefficient calculations using the UNIFAC model, is proposed. It takes into account both the partition of water between solvent and immobilized catalyst, and the partition of glycerol between solvent and silica gel. A good correlation with experimental data obtained in n-hexane/2M2B mixtures was observed. PMID:11240192
Rapid method for extracting aldrin, dieldrin, and endrin from visceral material.
Kurhekar, M P; D'souza, F C; Meghal, S K
A simple method is described for purifying aldrin, dieldrin, and endrin from visceral material by using a Celite column. Celite retains all interfering materials including Lipids whereas the chlorinated Insecticides are eluted from the column with n-hexane. This extract can be used directly for gas chromatographic analysis. PMID:1141184
Adsorption capacity study of carbon nanopowder produced by laser pyrolisis
NASA Astrophysics Data System (ADS)
Sonu, Marcel; Savu, Ion; Pastean, Laurentiu; Voicu, Ion N.; Soare, Iuliana; Morjan, Ion G.; Grigoriu, Constantin
The paper presents the experimental results on adsorption properties of carbon nanopowders which have been obtained by laser pyrolysis of hydrocarbon-based mixtures. We have investigated the adsorption of benzene, n-hexane and ciclohexane. The influence of the nanocarbon morphology (which depends on gaseous precursors and synthesis conditions) on adsorption characteristics is reported.
Study on Bioaccumulation of Lindane in Various Tissues of Channa gachua from Aurangabad District (MS) India
S. M. Shingare; M. V. Gaikwad; T. S. Pathan; P. B. Thete; Y. K. Khillare
To study bioaccumulation level of lindane in various tissues of Channa gachua, been studied for the present study, fishes were collected from nearby agricultural area, has. Tissues like muscle, kidney and liver are used for quantification of bioaccumulati on level of lindane. The tissues are blended with n-Hexane for extraction of pesticides and then were analyzed on Gas Chromatograph (GC,
Retention behaviour of nonylphenyl ethyleneoxide oligomers on alumina columns
Esther Forgßcs; Tibor Cserhßti
Nonylphenyl ethyleneoxide oligomers (surfactants) have been separated by HPLC on alumina columns with ethylacetate\\/n-hexane mixtures as eluents. Linear correlations have been established between the capacity factor and the concentration of ethylacetate in the mobile phase. It is assumed that the number of fractions eluted corresponds to the number of ethylene groups per molecule.
Control of charcoal rot fungus Macrophomina phaseolina by extracts of Datura metel.
Javaid, Arshad; Saddique, Amna
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?╣) 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?Ąg?mL?╣ 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
Oxidation of Benzyl Alcohols under Mild Heterogeneous Conditions
F. Shirini; M. A. Zolfigol; M. R. Azadbar
A combination of iodic acid with ammonium dichromate in the presence of wet SiO2 was used as an efficient oxidizing agent for the transformation of benzyl alcohols to the corresponding aldehydes and ketones in n-hexane or without a solvent at room temperature with excellent yields.
Physicochemical characterization and antimicrobial activity from seed oil of Pongamia pinnata, a potential biofuel crop
Vigya Kesari; Archana Das; Latha Rangan
Oil analysis and antimicrobial activity from seeds of elite genotype of Pongamia pinnata was carried out in the current study. The highest oil yield (33%) from seeds was recovered in n-Hexane. Physico-chemical properties of crude oil established suitability of P. pinnata for its use as a potential biofuel crop. The total mono unsaturated fatty acid (oleic acid 46%) present in
Toxicity of Solanum xanthocarpum fruit extract against Alternaria brassicae, causal agent of Alternaria blight of Indian mustard (Brassica juncea)
Sanjay Guleria; Ashok Kumar; A. K. Tiku
Fruit extract of Solanum xanthocarpum was evaluated for its toxicity against Alternaria brassicae, the causal agent of Alternaria blight of Indian mustard [Brassica juncea (L.) Czern. & Coss]. The mass obtained after vacuum drying of the crude methanolic extract was utilised for further sequential fractionation using n-hexane, ethyl acetate, n-butanol and methanol. Among the crude and different fractions tested, methanolic
Extract of Saccharina japonica induces apoptosis companied by cell cycle arrest and endoplasmic reticulum stress in SK-Hep1 human hepatocellular carcinoma cells.
Il Jung, Hyun; Jo, Mi Jeong; Kim, Hyung-Rak; Choi, Yung Hyun; Kim, Gun-Do
Saccharina japonica is a family member of Phaeophyceae (brown macro-alga) and extensively cultivated in China, Japan and Korea. Here, the potential anti-cancer effect of n-hexane fraction of S. japonica was evaluated in SK-Hep1 human hepatocellular carcinoma cells. The N-hexane fraction reduced cell viability and increased the numbers of apoptotic cells in a both dose- and time-dependent manner. Apoptosis was activated by both caspase-dependent and independent pathways. The caspase-dependent cell death pathway is mediated by cell surface death receptors and activated caspase-8 amplified the apoptotic signal either through direct activation of downstream caspase-3 or pro-apoptotic proteins (Bad, Bax and Bak) subsequently leading to the release of cytochrome c. On the other hand, caspase-independent apoptosis appeared mediated by disruption of mitochondrial membrane potential and translocation of AIF to the nucleus where they induced chromatin condensation and/or large-scale DNA fragmentation. In addition, the n-hexane fraction induced endoplasmic reticulum (ER)-stress and cell cycle arrest. The results suggested that potential anti-cancer effects of n-hexane extract from S. japonica on SK-Hep1 cells. PMID:24815436
Fischer-Tropsch synthesis in supercritical reaction media. Progress report, October 1, 1992--December 31, 1992
Subramaniam, B.; Bochniak, D.; Snavely, K.
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.
Fischer-Tropsch synthesis in supercritical reaction media
Subramaniam, B.; Bochniak, D.; Snavely, K.
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.
One-dimensional channels constructed from per-hydroxylated pillar[6]arene molecules for gas and vapour adsorption.
Ogoshi, Tomoki; Sueto, Ryuta; Yoshikoshi, Kumiko; Yamagishi, Tada-aki
Per-hydroxylated pillar[6]arene molecules formed highly ordered one-dimensional channels with a diameter of 6.7 ┼. The channels can capture various gases, such as CO2, N2 and n-butane, and vapours of saturated hydrocarbons such as n-hexane and cyclohexane. PMID:25339195
Perspectives Luis, an auto mechanic in his 20s,
Massachusetts at Lowell, University of
and consumers? N-hexane was used to replace methylene chloride and other toxic chlorinated solvents. New environmental regulations to protect the public had been promoted to reduce solvents in the air and wastewater--especially its effect on workers, who use it in much larger quantities than the average consumer. The larger
Heterogeneous Adsorption Characteristics of Volatile Organic Compounds (VOCs) on MCM?48
W. G. Shim; J. W. Lee; H. Moon
This work focuses on the fundamental studies of heterogeneous adsorption characteristics of mesoporous adsorbent. MCM?48 was synthesized to investigate the adsorption properties of eight different volatile organic compounds (benzene, cyclohexane, n?hexane, toluene, methanol, acetone, methyl ethyl ketone (MEK), and trichloroethylene (TCE)). The gravimetric method was used to measure the adsorption equilibrium amount. Several simple and reliable methods such as isosteric
The effect of artemisia annua on broiler performance, intestinal microbiota and on the course of a clostridium perfringens infection applying a necrotic enteritis disease model
Ricarda Margarete Engberg; Kai Grevsen; Elise Ivarsen; Xavier Frettķ; Lars Porskjµr Christensen; Ole H°jberg; Bent Borg Jensen; Nuria Canibe
The aerial parts of the plant Artemisia annua (A. annua) contain essential oils having antimicrobial properties against Clostridium perfringens Type A, the causal agent for necrotic enteritis in broilers. In two experiments, the influence of increasing dietary concentrations of dried A. annua leaves (0, 5, 10 and 20 g\\/kg) and n-hexane extract from fresh A. annua leaves (0, 125, 250
Protective effect of Emilia sonchifolia (L.) against high protein diet induced oxidative stress in pancreas of Wistar rats
Sophia, Dominic; Ragavendran, Paramasivam; Raj, Chinthamony Arul; Gopalakrishnan, Velliyur Kanniappan
Objectives: The present study was undertaken to investigate the oxidative damage, the biochemical and histopathological changes in the pancreas of the Wistar rats which was fed high protein diet and the recovery after the oral administration of the n-hexane extract of the herb, Emilia sonchifolia. Materials and Methods: The rats fed with high protein diet for a period of 30 days and treated with n-hexane extract of Emilia sonchifolia (250 mg/kg body weight). Body weight, pancreatic weight, serum amylase, lipase, aspartate transaminase, alanine transaminase, urea, uric acid, creatinine, DNA and RNA content of the pancreas, pancreatic enzymatic and non-enzymatic antioxidants such as superoxide dismutase, catalase, glutathione peroxidase, reduced glutathione, and vitamin C were evaluated. Results and Discussion: At the end of the study the rats gained less body weight and showed a significant (P < 0.05) increase in serum levels of amylase, lipase, aspartate transaminase, alanine transaminase, urea, uric acid, creatinine, tissue DNA, and RNA content and showed a significant (P < 0.05) decrease in the pancreatic antioxidants. Treatment with the n-hexane extract ameliorated the damage caused by high protein diet. This was also evidenced by histopathological studies. Conclusion: From the results, it was suggested that the n-hexane extract of Emilia sonchifolia has an effective medicinal property and can act as a pancreato-protective herb. PMID:22368400
40 CFR 63.945 - Test methods and procedures.
Code of Federal Regulations, 2010 CFR
...gases shall be as follows: (i) Zero air (less than 10 ppmv hydrocarbon in air); and (ii) A mixture of methane or n-hexane in air at a concentration of approximately, but less than 10,000 ppmv. (6) An owner or operator may choose to...
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...
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...
The paper describes a model for deep catalytic oxidation of hydrocarbon mixtures in the strong pore diffusion region. A laboratory-scale tubular catalytic reactor, used for low-temperature (160-360 C) deep catalytic oxidation of n-hexane and benzene as single components and in a ...
Using a relative rate technique, rate constants for the gas phase reactions of the OH radical with n-butane, n-hexane and a series of alkenes and dialkenes, relative to that for propene, have been determined in one atmosphere of air at 295 + or - 1K. The resulting rate constant d...
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...
Transport properties of nonelectrolyte liquid mixturesŚV. Viscosity coefficients for binary mixtures of benzene plus alkanes at saturation pressure from 283 to 393 K
J. H. Dymond; K. J. Young
Viscosity coefficient measurements at saturation pressure are reported for benzene + n-hexane, benzene + n-octane, benzene + n-decane, benzene + n-dodecane, benzene + n-hexadecane, and benzene + cyclohexane at temperatures from 283 to 393 K. The characteristic parameter G in the Grunberg and Nissan equation
azeotropic batch distillation with heterogeneous en trainers
I. Rodriguez-Donis; J. Acosta-Esquijarosa; V. Gerbaud; E. Pardillo-Fondevila
In this article, a systematic study of the separati on of the n-hexane - ethyl acetate mixture with an entrainer by heterogeneous azeotropic batch distillation is performed. Based upon the thermodynamic behaviour of the ternary mixtures, potential entrainers partially miscible with one or two original azeotropic compon ents are chosen. In all cases, the entrainer adds a heterogeneous binary or
Heterogeneous Batch Distillation Processes for Waste Solvent Recovery in Pharmaceutical Industry
Ivonne Rodriguez-Donis; Vincent Gerbaud; Alien Arias-Barreto; Xavier Joulia
A summary about our experiences in the introduction of heterogeneous entrainers in azeotropic and extractive batch distillation is presented in this work. Essential advantages of the application of heterogeneous entrainers are showed by rigorous simulation and experimental verification in a bench batch distillation column for separating several azeotropic mixtures such as acetonitrile Ś water, n hexane Ś ethyl acetate and
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...
PHOTOREACTION OF CHOLESTERYL CINNAMATE Y. TANAKA and H. TSUCHIYA
Boyer, Edmond
of the sample were measured during reaction upon irradiation with filtered light. For this JOURNAL DE PHYSIQUE-225 ░C, and compared with the solution reaction in n-hexane or diethyl ether. Cholesteryl rrans the course of the reaction on irradiation in comparison with the reaction in the isotropic solution. 1
Screening seeds of Scottish plants for antibacterial activity
Yashodharan Kumarasamy; Philip John Cox; Marcel Jaspars; Lutfun Nahar; Satyajit Dey Sarker
Based on ethnopharmacological and taxonomic information, seeds of 21 Scottish plant species from 14 different families were obtained from authentic seed suppliers. Their n-hexane, dichloromethane and methanol extracts were assessed for antibacterial activity against 11 pathogenic bacterial species. Methanol extracts of 11 plant species showed significant antibacterial activity. Malva moschata and Prunus padus were active against five bacterial species, Reseda
Comparison of genetic damage in brazilian footwear-workers exposed to solvent-based or water-based adhesive
Vanina Dahlstr÷m Heuser; Vanessa Moraes de Andrade; Juliana da Silva; Bernardo Erdtmann
Research has shown that workers employed in footwear manufacture are at increased risk of some cancers, the strongest evidence being for nasal cancer and leukemia. Footwear-workers are routinely exposed to complex mixtures of solvents in degreasers, cleaners, primers, and adhesives used in the production process as toluene, n-hexane, acetone, and possibly dust particles, additives in shoe materials and degradation products
Novel modified zeolites for energy-efficient hydrocarbon separations.
Arruebo, Manuel (University of Colorado, Boulder, CO); 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 (University of Colorado, Boulder, CO); Noble, Richard (University of Colorado, Boulder, CO)
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.
Effects of vapor-liquid equilibrium on wetting efficiency in hydrodesulfurization trickle-bed reactorsĀ
Mills, Anna Lisa
from 0. 5 to 5. 0 kg/ms/s at a constant gas flow rate. Schwartz et al. (1976) compared the apparent equilibrium constant of a linearly adsorbing tracer determined from a trickle-bed reactor to that obtained from totally wetted pellets. The internal... kg/ms/s, and independent of the gas flow rates of lx10 to 2x10 kg/mz/s. The tracer methods of Schwartz and Colombo were applied to cyclo- hexene and n-pentane tracers on activated alumina particles by Mills and Dudukovic (1981). As in the case...
Asphalt deposition in miscible floodsĀ
Hasan, Syed Mir Ahmed
ratio can K p be defined as, where K is the effective permeability Kd "o 0 to oil in the undisturbed portion of the reservoir and K is the ef- fective permeability to the displacing phase in the flooded portion of the reservoir. p. and p... significant effect on the permeability losses due to asphalt precipita- tion. The miscible agents used in their study were Soltrol i30, a light naphta, and n-Pentane, These hydrocarbons precipitate much less asphalt than do propane and butane, the main...
Electron spin lattice relaxation of the triplet state in disordered solids exhibits dispersion
NASA Astrophysics Data System (ADS)
Ozarowski, Andrzej; Qiang Wu, Jie; Maki, August H.
Global analysis of microwave-induced delayed phosphorescence (MIDP) of photoexcited triplet states at 1.2 K is employed to obtain their spin-lattice relaxation (SLR) rate constants, and other relevant parameters. The phosphorescence decay kinetics of quinoxaline in crystalline durene and n-pentane are predicted accurately, but not in disordered solids nor of tryptophan in aqueous glass. For the latter, the decay fits a bimodal SLR distribution; a subset decays with slow SLR and as predicted, while the remainder displays the expected decay properties of fast SLR. Although not following this bimodal pattern, SLR of quinoxaline in disordered solids also exhibits dispersion.
A correlation of water solubility in jet fuels with API gravity: aniline point percent aromatics, and temperature.Ā
Byington, Alonzo
, cycloparaffins, aromatics, and olefins. Paraffins have a chain-like structure of carbon atoms, and cyclo- paraffins contain rings of carbon atoms with the rings usually com- posed of five or six carbon atoms. Examples of these compounds are illustrated... as follows; HHHHH I I I I I ITIII HHHHH a a I I a-c ? c ? c ? ? c-a HC H Straight-chain paraffin (n?pentane) H Branched-chain paraffin (2?2, 4-trimethylpentane or isooctane) * References are given at the end of the paper. Cycloparaffin...
Self-ignition of S.I. engine model fuels: A shock tube investigation at high pressure
Fieweger, K.; Blumenthal, R.; Adomeit, G. [RWTH, Aachen (Germany). Inst. fuer Allegemeine Mechanik] [RWTH, Aachen (Germany). Inst. fuer Allegemeine Mechanik
The self-ignition of several spark-ignition (SI) engine fuels (iso-octane, methanol, methyl tert-butyl ether and three different mixtures of iso-octane and n-heptane), mixed with air, was investigated experimentally under relevant engine conditions by the shock tube technique. Typical modes of the self-ignition process were registered cinematographically. For temperatures relevant to piston engine combustion, the self-ignition process always starts as an inhomogeneous, deflagrative mild ignition. This instant is defined by the ignition delay time, {tau}{sub defl}. The deflagration process in most cases is followed by a secondary explosion (DDT). This transition defines a second ignition delay time, {tau}{sub DDT}, which is a suitable approximation for the chemical ignition delay time, if the change of the thermodynamic conditions of the unburned test gas due to deflagration is taken into account. For iso-octane at p = 40 bar, a NTC (negative temperature coefficient), behavior connected with a two step (cool flame) self-ignition at low temperatures was observed. This process was very pronounced for rich and less pronounced for stoichiometric mixtures. The results of the {tau}{sub DDT} delays of the stoichiometric mixtures were shortened by the primary deflagration process in the temperature range between 800 and 1,000 K. Various mixtures of iso-octane and n-heptane were investigated. The results show a strong influence of the n-heptane fraction in the mixture, both on the ignition delay time and on the mode of self-ignition. The self-ignition of methanol and MTBE (methyl tert-butyl ether) is characterized by a very pronounced initial deflagration. For temperatures below 900 K (methanol: 800 K), no secondary explosion occurs. Taking into account the pressure increase due to deflagration, the measured delays {tau}{sub DDT} of the secondary explosion are shortened by up to one order of magnitude.
Theoretical study of binding and permeation of ether-based polymers through interfaces.
Samanta, Susruta; Hezaveh, Samira; Roccatano, Danilo
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
Adsorption properties of lamellar silica
NASA Astrophysics Data System (ADS)
Kuznetsov, B. V.; Lanin, S. N.; Rakhmanova, T. A.; Smirnov, V. V.; Tsodikov, M. V.; Tarasova, D. V.
Isotherms and heats of adsorption of water, n-heptane, trimethylamine, and methanol (at 303 K) vapors and isotherms of adsorption of nitrogen (at 77 K) on the lamellar silica prepared by removing metals from natural mineral vermiculate were measured. The surface concentration of adsorption sites and their energetic characteristics were found to be similar to those of ordinary silicas. The distinction of the lamellar silica from ordinary silicas manifests itself through extended desorption branches, a feature that makes it possible to classify the lamellar silica under study as a limitedly swellable sorbent.
Kinetic modelling of a surrogate diesel fuel applied to 3D auto-ignition in HCCI engines
Bounaceur, Roda; Fournet, Renķ; Battin-Leclerc, Frķdķrique; Jay, S; Da Cruz, A Pires
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.
Solvent extraction of rare earth elements with mixtures of sec-octylphenoxy acetic acid and bis(2,4,4-trimethylpentyl) dithiophosphinic acid
Qiong Jia; Shanshan Tong; Zhiying Li; Weihong Zhou; Hongfei Li; Shulan Meng
The synergistic solvent extraction of samarium (III) with mixtures of sec-octylphenoxy acetic acid (CA12, H2A2) and bis(2,4,4-trimethylpentyl) dithiophosphinic acid (Cyanex301, H2B2) in n-heptane has been investigated from chloride medium. The methods of slope analysis and constant mole are used for the determination of the reaction. Samarium (III) is extracted with the mixture as SmH2Cl2AB2 instead of SmA3ĘHA or SmB3ĘHB when
Flame Extinguishment Properties of Dry Chemicals: Extinction Weights for Small Diffusion Pan Fires and Additional Evidence for Flame Extinguishment by Thermal Mechanisms
Curtis T. Ewing; Francis R. Faith; James B. Romans; J. Thomas Hughes; Homer W. Carhart
An experimental study was made of the extinguishment of a small n-heptane diffusion flame (25.5 cm dia. pan) by a number of dry-chemical powders Ś KHCO3, NH 4H2PO4, Na2B4O7 . 10H2O, (NH4)2SO4, K2CO 3, K4Fe(CN)6 . 3H2O, Na2CO 3, K2SO4, NaCl, Na2C2O 4, K2C2O4 . H2O, and Monnex. The minimum weight of each required for flame extinction was determined as
Pt-Re-Sn\\/Al 2O 3 trimetallic catalysts for naphtha reforming processes without presulfiding step
V. A. Mazzieri; J. M. Grau; C. R. Vera; J. C. Yori; J. M. Parera; C. L. Pieck
The n-heptane reforming and the cyclopentane hydrogenolysis reactions over noble metal monometallic catalysts (0.3% Pt), bimetallic catalysts (0.3% Pt, x% Re, x=0.1, 0.3, 0.9 and 2.0, sulfided) and trimetallic catalysts (0.3% Pt, 0.3% Re, y% Sn, y=0.1, 0.3, 0.6 and 0.9, unsulfided) were studied. The metal function was supported over a chlorided ?-alumina that provided the acid function. The reforming
Spectroscopic Studies of Intramolecular Proton Transfer in 2-(4-Fluorophenylamino)-5-(2,4-Dihydroxybenzeno)-1,3,4-Thiadiazole
Mariusz Gago?; Arkadiusz Matwijczuk; Daniel Kami?ski; Andrzej Niewiadomy; Rados?aw Kowalski; Grzegorz P. Karwasz
Spectroscopic studies of the biologically active compound 2-(4-fluorophenylamino)-5-(2,4-dihydroxybenzeno)-1,3,4-thiadiazole\\u000a (FABT), have been performed. Absorption studies in the UV-Vis region for FABT in polar solvents, like water or ethanol, exhibit\\u000a the domination of the enol form over its keto counterpart, with a broad absorption band centered around 340Ānm. In non-polar\\u000a solvents such as n-heptane or heavier alkanes the 340Ānm absorption band disappears
Superbenzene-porphyrin conjugates.
Lungerich, Dominik; Hitzenberger, Jakob F; Marcia, Mario; Hampel, Frank; Drewello, Thomas; Jux, Norbert
A free-base porphyrin carrying two hexabenzocoronene (HBC) substituents in a trans arrangement and its zinc complex have been prepared. The compounds were characterized extensively and found to form tricationic dimers in the gas phase. X-ray crystallography confirms for the zinc complex a profound ?-stacking of the HBC moieties. In contrast, the free-base porphyrin incarcerates n-heptane which essentially prevents ?-stacking. Upon excitation of the HBC substituents, efficient energy transfer to the central porphyrin is observed. PMID:25244699
Effect of several uncouplers of cell-to-cell communication on gap junction morphology in mammalian heart
J. DķlĶze; J. C. Hervķ
SummaryĀĀElectrical conduction in sheep Purkinje fibers has been blocked by three different procedures: (I) 1mm 2¢4-dinitrophenol, (II) 3.5mm\\u000a n-Heptan-1-ol (heptanol), and (III) treatment by a hypotonic (120 mOsmoles) Ca2+-free solution for half an hour, followed by return to normal conditions. The gap junction morphology was analyzed quantitatively\\u000a in freezefracture replicas and compared in electrically conducting and nonconducting fibers. It is
Viscosity of the binary systems 2-methyl-2-propanol with n-alkanes at T = (303.15, 308.15, 313.15, 318.15 and 323.15) K: Prediction and correlation ¢ New UNIFAC¢VISCO interaction parameters
Emila M. Äivkovi?; Mirjana Lj. Kijev?anin; Ivona R. Radovi?; Slobodan P. Ŗerbanovi?; Bojan D. Djordjevi?
Viscosities for the binary mixtures 2-methyl-2-propanol+n-heptane, +n-octane, +n-nonane and +n-decane have been measured at 303.15, 308.15, 313.15, 318.15 and 323.15K and atmospheric pressure. Viscosity deviations for the binary systems were fitted to the Redlich¢Kister polynomial equation.The UNIFAC¢VISCO and the ASOG¢VISCO methods were used to predict the dynamic viscosities of binary mixtures. The viscosity data have also been correlated by Teja¢Rice
Experimental and predicted excess molar enthalpies of binary mixtures containing 2,2?-oxybis[propane], benzene, butan-1-ol, 2-methylpropan-1-ol, 2-methyl-2-ene-1-propanol at 303.15 K
Saķda Didaoui; Ahmed Ait-Kaci
Excess molar enthalpies HE have been measured for liquid binary mixtures of 2,2?-oxybis[propane] (diisopropylether æDIPEÆ), or, benzene+butan-1-ol, +2-methylpropan-1-ol (isobutanol), +2-methyl-2-ene-1-propanol (isobutenol), +n-heptane at 303.15K and constant pressure using a C80, Setaram calorimeter. A Redlich¢Kister type equation was used to correlate experimental results.These experimental results, along with our previous data on HE of DIPE+benzene, +cyclohexane [1] are used for estimating interaction
The preparation and characterization of Li 4Ti 5O 12\\/carbon nano-tubes for lithium ion battery
Junjie Huang; Zhiyu Jiang
Li4Ti5O12\\/carbon nano-tubes (CNTs) composite was prepared by sol¢gel method while Ti(OC4H9)4, LiCH3COOĘ2H2O and the n-heptane containing CNTs were used as raw materials. The characters of Li4Ti5O12\\/CNTs composite were determined by XRD, SEM, and TG methods. Its electrochemical properties were measured by charge¢discharge cycling and impedance tests. It was found that the prepared Li4Ti5O12\\/CNTs presented an excellent rate capability and capacity
Low and intermediate temperature oxidation of ethanol and ethanol-PRF blends: An experimental and modeling study
Haas, Francis M.; Chaos, Marcos; Dryer, Frederick L. [Department of Mechanical and Aerospace Engineering, Princeton University, Princeton, NJ 08544 (United States)
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)
The Effects of Aliphatic ( n-Nonane), Naphtenic (1,2,4-Trimethylcyclohexane), and Aromatic (1,2,4Trimethylbenzene) Hydrocarbons on Respiratory Burst in Human Neutrophil Granulocytes
O. Myhre; T. A. Vestad; E. Sagstuen; H. Aarnes; F. Fonnum
This study investigates the effects of aliphatic (n-heptane, n-nonane), naphtenic (methylcyclohexane, 1,2,4-trimethylcyclohexane (TMCH)), and aromatic (methylbenzene, 1,2,4-trimethylbenzene (TMB)) hydrocarbons on respiratory burst in human granulocytes. The free radical formation was measured as 2,7-dichlorofluorescein diacetate-amplified (DCF) fluorescence, by electron paramagnetic resonance (EPR) spectroscopy and by hydroxylation of 4-hydroxybenzoate. The chemotactic peptide N-formyl-met-leu-phe (fMLP) and phorbol 12-myristate 13-acetate (PMA), a diacylglycerol analogue,
Migration of Irganox 1010 from ethylene-vinyl acetate films to foods and food-simulating liquids.
Schwope, A D; Till, D E; Ehntholt, D J; Sidman, K R; Whelan, R H; Schwartz, P S; Reid, R C
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
Chemical kinetic mechanism for the oxidation of paraffinic hydrocarbons needed for primary reference fuels
Westbrook, C.K.; Pitz, W.J.
A detailed chemical kinetic reaction mechanism is described which simulates the oxidation of the primary reference fuels n-heptane and iso-octane. The high temperature subset of these mechanisms is identified, and the extensions to deal with low temperature conditions are also explained. The algorithms used to assign reaction rates to elementary steps in the reaction mechanism are described, and the means of identifying the different chemical species and the relevant reactions are outlined. Finally, we show how interested kinetic modeling researchers can obtain copies of this reaction mechanism.
On sub-T(g) dewetting of nanoconfined liquids and autophobic dewetting of crystallites.
Souda, Ryutaro
The glass transition temperature (T(g)) of thin films is reduced by nanoconfinement, but it is also influenced by the free surface and substrate interface. To gain more insights into their contributions, dewetting behaviors of n-pentane, 3-methylpentane, and toluene films are investigated on various substrates as functions of temperature and film thickness. It is found that monolayers of these molecules exhibit sub-T(g) dewetting on a perfluoro-alkyl modified Ni substrate, which is attributable to the evolution of a 2D liquid. The onset temperature of dewetting increases with film thickness because fluidity evolves via cooperative motion of many molecules; sub-T(g) dewetting is observed for films thinner than 5 monolayers. In contrast, monolayers wet substrates of graphite, silicon, and amorphous solid water until crystallization occurs. The crystallites exhibit autophobic dewetting on the substrate covered with a wetting monolayer. The presence of premelting layers is inferred from the fact that n-pentane crystallites disappear on amorphous solid water via intermixing. Thus, the properties of quasiliquid formed on the crystallite surface differ significantly from those of the 2D liquid formed before crystallization. PMID:22337324
Adsorption of selected volatile organic vapors on multiwall carbon nanotubes.
Shih, Yang-hsin; Li, Mei-syue
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
Determination of organochlorine and pyrethroid pesticides in fruit and vegetables using solid phase extraction clean-up cartridges.
Sharif, Zawiyah; Man, Yaakob Bin Che; Hamid, Nazimah Sheikh Abdul; Keat, Chin Cheow
A method to determine six organochlorine and three pyrethroid pesticides in grape, orange, tomato, carrot and green mustard based on solvent extraction followed by solid phase extraction (SPE) clean-up is described. The pesticides were spiked into the sample prior to analysis, extracted with ethyl acetate, evaporated and reconstituted with a solvent mixture of acetone:n-hexane (3:7). Three different sorbents (Strong Anion Exchanger/Primary Secondary Amine (SAX/PSA), Florisil and C18) were used for the clean-up step. Pesticides were eluted with 5mL of acetone:n-hexane (3:7, v/v) and determined by gas chromatography and electron-capture detection (GC-ECD). SAX/PSA was the sorbent, which provided chromatograms with less interference and the mean recoveries obtained were within 70-120% except for captafol. The captafol recoveries for grape were within acceptable range with C18 clean-up column. PMID:16857206
Vitiquinolone--a quinolone alkaloid from Hibiscus vitifolius Linn.
Ramasamy, D; Saraswathy, A
Phytochemical investigations of the powdered root of Hibiscus vitifolius Linn. (Malvaceae) was extracted successively with n-hexane and chloroform. Analysis of the n-hexane extract by GC-MS led to the identification of twenty-six components by comparison of their mass spectra with GC-MS library data. A novel quinolone alkaloid, vitiquinolone (5) together with eight known compounds viz. ?-Amyrin acetate (1), n-octacosanol (2), ?-Amyrin (3), stigmasterol (4), xanthyletin (6), alloxanthoxyletin (7), xanthoxyletin (8) and betulinic acid (9) were isolated from chloroform extract by column chromatography over silica gel. The structure of vitiquinolone was established on the basis of spectroscopic methods including UV, IR, 1D, 2D NMR and ESI-MS. The known compounds were identified on the basis of their physical and spectroscopic data as reported in the literature. PMID:24128571
Glycerol monooleate reverse micelles in nonpolar solvents: computer simulations and small-angle neutron scattering.
Bradley-Shaw, Joshua L; Camp, Philip J; Dowding, Peter J; Lewtas, Ken
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 ┼, 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 ┼. 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
Laminar burning velocities at high pressure for primary reference fuels and gasoline: Experimental and numerical investigation
Jerzembeck, S.; Peters, N. [RWTH, Aachen (Germany); Pepiot-Desjardins, P.; Pitsch, H. [Department of Mechanical Engineering, Stanford University, CA (United States)
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)
Interaction forces between asphaltene surfaces in organic solvents.
Wang, Shengqun; Liu, Jianjun; Zhang, Liyan; Masliyah, Jacob; Xu, Zhenghe
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
Barrera, J.; Smith, D.C.; Devlin, D.J.
This is the final report of a three-year, Laboratory Directed Research and Development (LDRD) project at the Los Alamos National Laboratory (LANL). Highly selective, alumina-supported molybdenum carbonitrides were prepared by solution impregnation using the metal amide Mo{sub 2}(N(CH{sub 3}){sub 2}){sub 6} as a molecular precursor. On the basis of relative weight percents, these materials demonstrate a 5- to 8-fold increase in catalytic activity over similar materials prepared by traditional solid-state approaches. The catalytic activities of these materials are very dependent upon the type of alumina support used. Impregnation of Mo{sub m}C{sub x}N{sub y} into preformed alumina pellets resulted in a material that specifically isomerized n-heptane into equal amounts of 2- and 3-methylhexanes, as well as iso-butane. No evidence of aromatic products was observed at operating temperatures below 420{degrees}C. The product selectivity of the isomers was 56% at a n-heptane conversion efficiency of 57%. Impregnating Mo{sub m}C{sub x}N{sub y} into an alumina powder resulted in an extremely selective aromatized and dehydrogenated material. The products from this material consist only of aromatics and n-heptenes with less than 2% isomerization or cracking products.
Group type analysis of asphalt by column liquid chromatography
Zhang, C.; Yang, J.; Xue, Y.; Li, Y. [Chinese Academy of Science, Taiyuan (China)
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.
Development of efficient SPE¢TLC method and evaluation of biological interactions of contraceptives with progesterone receptors
Imran Ali; Iqbal Hussain; Kishwar Saleem; Hassan Y. Aboul-Enein
TLC¢SPE methodologies were developed to ascertain biological interactions of norethindrone acetate and dydrogesterone contraceptives with plasma progesterone receptor proteins. TLC solvent system for plain and Cu(II) impregnated silica gel plates was n-hexane-n-butanol (90:10, v\\/v), which took 20min to run up to 10.0cm. The best separation was on Cu(II) impregnated plates due to maximum difference in Rf values and compact spots.
Fatal intoxication with tianeptine ( Stablon «)
Paula Proenńa; Helena Teixeira; JoŃo Pinheiro; Paula V. Monsanto; Duarte Nuno Vieira
Tianeptine (Stablon«), although structurally similar to tricyclic antidepressants, acts by enhancing the reuptake of serotonin. A fatal case is presented involving a 26-year-old man, found lying in bed with a ōmushroom of foamö around his mouth. Empty blister packs of Stablon« and a suicide note were found next to the body. A liquid¢liquid extraction procedure with n-hexane: ethyl acetate and
HPLC analysis of coumarins in Turkish Seseli species (Umbelliferae)
Alev Tosun; Masaki Baba; Toru Okuyama
The n-hexane extracts of aerial and underground parts of three Seseli species, S. gummiferum subsp. corymbosum, S. resinosum, and S. hartvigii growing in Turkey were investigated concerning the presence of coumarins by normal-phase HPLC (high-performance liquid chromatography).\\u000a In this respect, two coumarins, osthol (1) and corymbocoumarin (2) [(?)-(3?S, 4?S)-3?-acetoxy-4?-isovaleryloxy-3?, 4?-dihydroseselin] isolated from aerial parts of S. gummiferum subsp. corymbosum, were
Antioxidant Potential ofEcklonia cavaon Reactive Oxygen Species Scavenging, Metal Chelating, Reducing Power and Lipid Peroxidation Inhibition
Mahinda Senevirathne; Soo-Hyun Kim; Nalin Siriwardhana; Jin-Hwan Ha; Ki-Wan Lee; You-Jin Jeon
The antioxidative potential of different fractions (respective organic and aqueous fractions of n-hexane, chloroform and ethyl acetate) of 70% methanol extract of Ecklonia cava(a brown seaweed) was evaluated using 1,1-diphenyl-2-picrylhydrazyl (DPPH), superoxide anion, hydrogen peroxide, hydroxyl radical, nitric oxide, ferrous ion chelating, reducing power and lipid peroxidation inhibition (conjugated diene hydroperoxide and thiobarbituric acid-reactive substances production) assays. The 70% methanol
Development and validation of an enantioselective liquid-chromatography\\/tandem mass spectrometry method for the separation and quantification of eslicarbazepine acetate, eslicarbazepine, R-licarbazepine and oxcarbazepine in human plasma
A. I. Loureiro; C. Fernandes-Lopes; L. C. Wright; P. Soares-da-Silva
The purpose of this study was develop and validate a sensitive and specific enantioselective liquid¢chromatography\\/tandem mass spectrometry (LC¢MS\\/MS) method, for the simultaneous quantification of eslicarbazepine acetate (ESL), eslicarbazepine (S-Lic), oxcarbazepine (OXC) and R-licarbazepine (R-Lic) in human plasma. Analytes were extracted from human plasma using solid phase extraction and the chromatographic separation was achieved using a mobile phase of 80% n-hexane
Monte Carlo simulation of the adsorption of C2¢C7 linear alkanes in aluminophosphate AlPO4-11
D. Zhang; Z. Liu; R. Xu
The adsorption behaviors of linear alkanes ranging in length from C2 to C7 in AlPO4-11 have been simulated by using configurational-bias Monte Carlo technique at 313ĀK. The calculated heats of adsorption at zero coverage for linear alkanes, estimated by Henry coefficients, are consistent well with previously reported experimental and simulation results. The simulated isotherms for n-hexane in AlPO4-11 at 298ĀK
Catalytic conversion of C 6-alkanes over Pd\\/Al 2O 3 catalysts
Maciej Skotak; Dariusz ?omot; Zbigniew Karpi?ski
A comparable study of catalytic conversion of two C6-alkanes (n-hexane and 2,2-dimethybutane) has shown several analogies in the catalytic behavior of a series of differently loaded, chlorine-free Pd\\/Al2O3 catalysts. Different sample pretreatments have been used to modify the catalytic behavior. The catalytic performance of lowly reduced (at 573K) samples of Pd\\/Al2O3 catalysts is similar to that exhibited by unsupported or
On the influence of the mordenite acidity in the hydroconversion of linear alkanes over Pt-mordenite catalysts
Luis Oswaldo Almanza; Thomas Narbeshuber; Paolo d'Araujo; Claude Naccache; YounĶs Ben Taarit
Hydroconversion of n-octane and n-hexane was investigated on a series of platinum loaded mordenite samples with varied framework aluminium (FAl) content. In agreement with previous authors, it was observed that the rate of hydroconversion is first increased almost linearly with the number of FAl per unit cell, reached a maximum then decreased abruptly as the number of the FAl\\/unit cell
Characterization and catalytic activity of differently pretreated Pd\\/Al 2O 3 catalysts: the role of acid sites and of palladium¢alumina interactions
M. Skotak; Z. Karpi?ski; W. Juszczyk; J. Pielaszek; L. K?pi?ski; D. V. Kazachkin; V. I. Kovalchuk; J. L. d'Itri
The effect of catalyst pretreatment on the performance of chlorine-free ?-alumina-supported palladium catalysts with metal loadings in the range of 0.3 to 2.77 wt% has been investigated in the hydroconversion of n-hexane (nH) and 2,2-dimethylbutane (22DMB) at 290?░C and atmospheric pressure. The catalyst properties were modified by varying the catalyst pretreatment: low-temperature reduction (LTR) at 300?░C; high-temperature reduction (HTR) at
Amphiphilic molecular gels from ?-aminoalkylated l -glutamic acid derivatives with unique chiroptical properties
Yoshiko Kira; Yutaka Okazaki; Tsuyoshi Sawada; Makoto Takafuji; Hirotaka Ihara
Self-assembling amphiphiles with unique chiroptical properties were derived from l-glutamic acid through ?-aminoalkylation and double long-chain alkylation. These amphiphiles can disperse in various solvents\\u000a ranging from water to n-hexane. TEM and SEM observations indicate that the improvement in dispersity is induced by the formation of tubular and\\/or\\u000a fibrillar aggregates with nanosized diameters, which makes these amphiphiles similar to aqueous lipid
Use of Alumina Support for the Separation of Ethoxylated Oligomer Surfactants According to the Length of the Ethyleneoxide Chain
E. Forgßcs; T. Cserhßti
The theoretical plate number, capacity factor, peak assymetry and separation factor of an alumina high-performance liquid chromatographic column were determined using nonylphenyl ethylene oxide oligomers as solutes and eluents containing n-hexane, dichloromethane, dioxane, tetrahydrofuran, chloroform and ethyl acetate. The relationship between the chromatographic characteristics and physicochemical parameters of the stronger component in the eluent was calculated by multivariate mathematical-statistical methods.
Phytochemical and biological studies on Nephelium longan (Estudios fitoquĒmicos y biol¾gicos sobre Nephelium longan)
Khondaker M. RAHMAN; Kamrun NAHAR; Mohammad Gias; Uddin KHAN; Choudhury M. HASAN
Extensive chromatographic separation and purification of the organic solvent extracts of Nephelium longan (Sapindaceae) stem bark afforded two compounds; scopoletin and stigmasterol. The structures of these compounds were determined by spectroscopic analyses, including 1H and 13C NMR. Different crude extracts (n-hexane, carbon tetrachloride, chloroform and methanol) were tested for antimicrobial activity by standard disc diffusion method known as the Kirby-Bauer
Simultaneous determination of amitraz and its metabolite residue in food animal tissues by gas chromatography-electron capture detector and gas chromatography¢mass spectrometry with accelerated solvent extraction
Huan Yu; Yanfei Tao; Tao Le; Dongmei Chen; Awais Ishsan; Yu Liu; Yulian Wang; Zonghui Yuan
A new method has been developed for determination and confirmation of amitraz and its main metabolite, 2,4-dimethylaniline, in food animal tissues using gas chromatography-electron capture detector (GC-ECD) and gas chromatography¢mass spectrometry detector (GC¢MS). This method is based on a new extraction procedure using accelerated solvent extraction (ASE). It consists of an n-hexane\\/methanol extraction step, a cleaning-up step by BakerBond octadecyl
Antileishmanial amides and lignans from Piper cubeba and Piper retrofractum
Hardik S. Bodiwala; Gaganmeet Singh; Ranvir Singh; Chinmoy Sankar Dey; Shyam Sundar Sharma; Kamlesh Kumar Bhutani; Inder Pal Singh
The n-hexane, ethyl acetate, methanol, and acetone extracts of Piper cubeba Linn. and P. retrofractum Vahl. (Piperaceae) were evaluated in vitro against promastigotes of Leishmania donovani, and all exhibited significant in vitro activity at 100Ā?g\\/ml. Two lignans, cubebin and hinokinin, were isolated from the\\u000a hexane extract of P. cubeba; and one bis-epoxy lignan, (?)-sesamin, and two amides, pellitorine and piplartine,
Constituents of Chinese Piper species and their inhibitory activity on prostaglandin and leukotriene biosynthesis in vitro
Jochen R. St÷hr; Pei-Gen Xiao; Rudolf Bauer
The n-hexane extracts of 19 Piper species, predominantly from China, were screened for their 5-lipoxygenase (5-LOX) and cyclooxygenase-1 (COX-1) inhibitory potential. Many of them showed considerable inhibitory activity against at least one of these two key enzymes of the arachidonic acid metabolism, especially against COX-1. The best results in inhibiting the formation of leukotrienes were obtained with the extract of
Analysis of crude drugs using reversed-phase TLC\\/scanning densitometry. (II) Identification of ginseng, red ginseng, gentian, Japanese gentian, pueraria root, gardenia fruit, schisandra fruit and ginger
Tsutomu Ohno; Eiichi Mikami; Hisao Oka
We performed identification tests of the main components (ginsenoside-Rg1, gentiopicroside, puerarin, geniposide, schizandrin, and [6]-gingerol) of the following crude drugs from the Japanese Pharmacopoeia, 14th edition (JP14): ginseng, red ginseng, gentian, Japanese gentian, pueraria root, gardenia fruit, schisandra fruit, and ginger). The identification was carried out with reversed-phase thin-layer chromatography using water, acetonitrile, methanol, 2-butanone, and n-hexane as developing solvents.
Synthesis of hydrophilic and hydrophobic xerogels with superior properties using sodium silicate
Pradip B. Sarawade; Jong-Kil Kim; Askwar Hilonga; Dang Viet Quang; Hee Taik Kim
Highly porous hydrophilic and hydrophobic silica xerogels were synthesized by surface modification of silica hydrogels at ambient pressure drying. The silica hydrogels were prepared by a sol¢gel polymerization of an inexpensive silica precursor (sodium silicate) under atmospheric conditions. In order to minimize shrinkage due to drying, the hydrogel surface was modified using trimethylchlorosilane (TMCS) in the presence of ethanol\\/n-hexane solution
Preparative isolation and purification of Xanthohumol from Hops (Humulus lupulus L .) by high-speed counter-current chromatography
Chen Qi-he; Fu Ming-liang; Chen Miao-miao; Liu Jing; Liu Xiao-jie; He Guo-qing; Pu Shou-cheng
Xanthohumol (XN) and related prenylflavonoids are the main bioactive components of Hops (Humulus lupulus L.). The current work is to investigate the use of high-speed counter-current chromatography (HSCCC) in search for high isolation of xanthohumol from Hops. A solvent system consisted of n-hexane¢ethyl acetate¢methanol¢water at a volume ratio of 5:5:4:3 was employed. The results demonstrated that the constructed method could
Use of HMDS\\/hexane double layers for obtaining low cost selective membrane
Maria Lucia P. da Silva; Nicole R. Demarquette; Ing H. Tan
Sheets of paper commonly used for filtration were coated with double layers of HMDS (hexamethyl disilazane) and n-hexane using a low pressure plasma reactor. The organic compounds formed a thin film with very good adhesion to the substrate; the process produced water-repellent surfaces, with apparent water-contact angles higher than 100░ and water adsorption around 15 g\\/m2. The paper porosity was
Biodegradation of methyl tert-butyl ether by cometabolism with hexane in biofilters inoculated with Pseudomonas aeruginosa
Margarita Salazar; Marcia Morales; Sergio Revah
Biodegradation of methyl tert-butyl ether (MTBE) vapors by cometabolism with gaseous hexane (n-hexane > 95%) was investigated using Pseudomonas aeruginosa utilizing short chain aliphatic hydrocarbon (C5-C8). Kinetic batch experiments showed that MTBE was degraded even when hexane was completely exhausted with a cometabolic coefficient of 1.06 ▒ 0.16 mg MTBE mg hexane. Intermediate tert-butyl alcohol (TBA) accumulation was observed followed
In vitro and in vivo anti-angiogenesis effect of shallot ( Allium ascalonicum): A heat-stable and flavonoid-rich fraction of shallot extract potently inhibits angiogenesis
Parivash Seyfi; Ali Mostafaie; Kamran Mansouri; Delnia Arshadi; Hamid-Reza Mohammadi-Motlagh; Amir Kiani
This study has been undertaken to elucidate the anti-angiogenic properties of shallot extract in vitro and in vivo and also to define the responsible fraction and its stability. After preparation of the extract of shallot bulbs with 50% ethanol, the extract was successively fractionated into n-hexane, ethyl acetate, n-butanol and aqueous fractions. The ethyl acetate fraction was further fractionated to
Nutrient Limitation in a Compost Biofilter Degrading Hexane
Eberhard Morgenroth; Edward D. Schroeder; Daniel P. Y. Chang; Kate M. Scow
A laboratory-scale compost-based biofilter was operated over a six-month period to study the requirements for removal of n-hexane from air. Hexane is a relatively short chain aliphatic hydrocarbon with a high Henry's coefficient and a low water solubility. Acclimation of the biofilter was slow, but removal efficiencies around 80% were achieved after one month of operation. However, performance decreased during
Purification of icariin from the extract of Epimedium segittatum using high-speed counter-current chromatography
Qizhen Du; Ming Xia; Yoichiro Ito
Icariin was purified from the extract of Epimedium segittatum by high-speed counter-current chromatography with a two-phase solvent system composed of n-hexane¢n-butanol¢methanol¢water (1:4:2:6, v\\/v). We used two multilayer coil planet centrifuges with different capacities. A 300 mg amount of the extract was separated using a semipreparative instrument equipped with a 230-ml capacity column to yield 103 mg of icariin at 86.2%
Antimycotic activities of Cinnamon-derived compounds against Rhizoctonia solani in vitro
Van-Nam Nguyen; Dang-Minh-Chanh Nguyen; Dong-Jun Seo; Ro-Dong Park; Woo-Jin Jung
In this study, the effects of medicinal plant extracts on the development of mycelium in the following phytopathogenic fungi\\u000a were evaluated: Phytophthora capsici, Rhizoctonia solani, Fusarium solani, Colletotrichum gloeosprorioides, and Botrytis cinera. Of the 26 medicinal plants tested, six plant extracts showed antifungal activity against phytopathogenic fungi. The highest\\u000a antifungal activity was exerted against R. solani by the n-hexane fraction
A study of platinum-thulium\\/KL zeolite reforming catalysts
Xiangming Fang; Fengyi Li; Laitao Luo
The PtKL catalyst modified by Tm2O3 has been characterized by the n-hexane, methylcyclopentane (MCP) and cyclohexane conversion reaction. The results show that the activity for the aromatization on Pt-Tm\\/KL zeolite catalysts containing thulium ranging from 0.05 to 0.2 wt.-% is higher than that on the PtKL catalyst, and the stability of the modified catalysts is remarkably improved. The influence of
Enantiomeric resolution of bupivacaine by high-performance liquid chromatography and chiroptical detection
F. G. Sßnchez; A. N. DĒaz; A. B. M. de Vicente
This work reports a new analytical procedure for the separation and determination of the enantiomers of bupivacaine and the determination of the enantiomeric purity. The isomers were separated using a Chirex 3020 (250mmū4.6mm) with a mobile phase of n-hexane:dichloroethane:ethanol (82:9:9, v\\/v\\/v) at a flow-rate of 1mlmin?1 and UV, polarimetric and circular dichroism (CD) detection. Obtained retention times were 5.93 and
Activity-guided isolation of antiplasmodial dihydrochalcones and flavanones from Piper hostmannianum var. berbicense
Bķnķdicte Portet; Nicolas Fabre; Vincent Roumy; Heinz Gornitzka; GeneviĶve Bourdy; Sķverine Chevalley; Michel Sauvain; Alexis Valentin; Claude Moulis
The bioassay-guided purification of an n-hexane extract from the leaves of Piper hostmannianum var. berbicense led to the isolation of four monoterpene or prenyl-substituted dihydrochalcones (1a, 1b, 2, 3) as well as the known compounds 2?,6?-dihydroxy-4?-methoxydihydrochalcone (4), linderatone (5), strobopinin (6), adunctin E (7) and (?)-methyllinderatin (8). Their structures were established on the basis of NMR and X-ray analysis. (?)-Methyllinderatin,
Isoprenylated xanthone and benzophenone constituents of the pericarp of Garcinia planchonii.
Trinh, Duong Hoang; Ha, Ly Dieu; Tran, Phuong Thu; Nguyen, Lien-Hoa Dieu
A new xanthone, planchoxanthone (1), together with six known compounds, garcinianone A (2), cowanin (3), rubraxanthone (4), f-mangostin (5), dulcisxanthone B (6), and guttiferone Q (7), were isolated from an n-hexane extract of the pericap of Garcinia planchonii. Their structures were elucidated using spectroscopic methods. Antioxidant activity of the isolated compounds was tested using the DPPH free radical scavenging assay. PMID:25632472
Green procedure with a green solvent for fats and oilsÆ determination
Matthieu Virot; Valķrie Tomao; Christian Ginies; Franco Visinoni; Farid Chemat
Here is described a green and original alternative procedure for fats and oilsÆ 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,
Antioxidant potential of corncob extracts for stabilization of corn oil subjected to microwave heating
Bushra Sultana; Farooq Anwar; Roman Przybylski
Antioxidant effectiveness of corncob extract with different polarity solvents (n-hexane, ethyl acetate, acetone, ethanol, and methanol) was assessed for total phenolics content (TPC), DPPH radical scavenging activity and % inhibition of peroxidation in linoleic acid system. The yield of the extracts from corncob with different solvents ranged from 1.1 to 19.5 g\\/100g of dry matter. TPC, DPPH radical scavenging and
Experimental Investigation of the Low Temperature Oxidation of the Five Isomers of Hexane
Boyer, Edmond
of the five hexane isomers (n-hexane, 2-methyl-pentane, 3-methyl-pentane, 2,2-dimethyl-butane, and 2,3-dimethyl-butane) was studied in a jet-stirred reactor (JSR) at atmospheric pressure under stoichiometric-hexane. 2,2-Dimethyl-butane was less reactive than the two methyl-pentane isomers, and 2,3-dimethyl-butane
Attraction of the parasitic mite varroa to the drone larvae of honey bees by simple aliphatic esters.
Le Conte, Y; Arnold, G; Trouiller, J; Masson, C; Chappe, B; Ourisson, G
An important parasitic threat to honey bees, the mite Varroa jacobsoni, is attracted to its major prey, drone larvae, by methyl and ethyl esters of straight-chain fatty acids, in particular methyl palmitate. These esters were extracted from drone larvae with n-hexane and were identified by gas chromatography-mass spectrometry. Their behavioral effect was evaluated with the use of a four-arm airflow olfactometer. PMID:17837619
Attraction of the Parasitic Mite Varroa to the Drone Larvae of Honey Bees by Simple Aliphatic Esters
Yves Le Conte; Gerard Arnold; Jerome Trouiller; Claudine Masson; Bertrand Chappe; Guy Ourisson
An important parasitic threat to honey bees, the mite Varroa jacobsoni, is attracted to its major prey, drone larvae, by methyl and ethyl esters of straight-chain fatty acids, in particular methyl palmitate. These esters were extracted from drone larvae with n-hexane and were identified by gas chromatography-mass spectrometry. Their behavioral effect was evaluated with the use of a four-arm airflow
Attraction of the Parasitic Mite Varroa to the Drone Larvae of Honey Bees by Simple Aliphatic Esters
NASA Astrophysics Data System (ADS)
Le Conte, Yves; Arnold, Gerard; Trouiller, Jerome; Masson, Claudine; Chappe, Bertrand; Ourisson, Guy
An important parasitic threat to honey bees, the mite Varroa jacobsoni, is attracted to its major prey, drone larvae, by methyl and ethyl esters of straight-chain fatty acids, in particular methyl palmitate. These esters were extracted from drone larvae with n-hexane and were identified by gas chromatography-mass spectrometry. Their behavioral effect was evaluated with the use of a four-arm airflow olfactometer.
Determination of propoxur residues in eggs by liquid chromatography¢diode array detection after treatment of stocked housing facilities for the poultry red mite ( Dermanyssus gallinae)
Gerd Hamscher; Beate Prie▀; J÷rg Hartung; Monika I. Nogossek; Gerhard Gl³nder; Heinz Nau
A sensitive and selective liquid chromatography¢diode array detection method for the determination of propoxur in eggs is described. Eggs were homogenized, extracted with acetonitrile and partitioned with n-hexane. Further clean-up of the acetonitrile extract was undertaken using silica gel column chromatography. Quantitative detection was performed by liquid chromatography with UV detection at 220nm and confirmation of the residue was achieved
Synthesis and pore analysis of aerogel¢glass fiber composites by ambient drying method
Chang-Yeoul Kim; Jong-Kyu Lee; Byung-Ik Kim
Flexible aerogel¢glass fiber composites were prepared by varying colloidal silica and tetraethylorthosilicate (TEOS)-based sol fractions. After immersing glass fiber matrices into silica sol with different volume fraction of colloidal silica sol, it was surface-modified into trimethylchlorosilane\\/n-hexane solution and heat-treated at 230░C in ambient atmosphere. From the results of Brunauer¢Emmett¢Teller (BET) surface area, Barrett¢Joyner¢Halenda (BJH) pore size analyses, apparent density and
Amount-dependent isotopic fractionation during compound-specific isotope analysis
Jochen Schmitt; Bruno Glaser; Wolfgang Zech
Particular attention is paid to the localization of the amount-dependent isotopic fractionation with- in the system. Injection experiments with varying amounts of gases (CO2, n-hexane, and toluene) revealed that neither the detector unit nor the combustion reactor, but rather the conditions in the split\\/splitless injector, contributed to this effect. Although optimization of injector parameters was performed and a reduction of
Antioxidant Activity and Cytotoxicity of the Traditional Indonesian Medicine Tahongai ( Kleinhovia hospita L.) Extract
Enos Tangke Arung; Irawan Wijaya Kusuma; Sri Purwatiningsih; Seong-Soo Roh; Chae Ha Yang; Soohyeon Jeon; Yong-Ung Kim; Edi Sukaton; Joko Susilo; Yuli Astuti; Britanto Dani Wicaksono; Ferry Sandra; Kuniyoshi Shimizu; Ryuichiro Kondo
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
Comparative evaluation of urinalysis and blood analysis as means of detecting exposure to organic solvents at low concentrations
Toshio Kawail; Tomojiro Yasugi; Kazunori Mizunuma; Shun'ichi Horiguchi; Hiroshi Iguchi; Yoko Uchida; Okujou Iwami; Masayuki Ikeda
One hundred and forty-three workers exposed to one or more of toluene, xylene, ethylbenzene, styrene, n-hexane, and methanol at sub-occupational exposure limits were examined for the time-weighted average intensity of exposure by diffusive sampling, and for biological exposure indicators by means of analysis of shift-end blood for the solvent and analysis of shift-end urine for the corresponding metabolite(s). Urinalysis was
These guidelines describe Nature's standards for experimental methods and characterization of new compounds. Please provide adequate data
Napp, Nils
C-NMR for all new compounds, with other NMR data (31 P-NMR, 19 F-NMR, and so on) when appropriate-1 dm-1 )=-21.5 (c=0.1 g cm-3 in n-hexane); 1 H-NMR (400 MHz, CDCl3): 9.30 p.p.m. (s, 1H), 7 through spectroscopic analysis. Please provide standard peak listings for 1 H-NMR and proton-decoupled 13
Determination of organochlorine and pyrethroid pesticides in fruit and vegetables using solid phase extraction clean-up cartridges
Zawiyah Sharif; Yaakob Bin Che Man; Nazimah Sheikh Abdul Hamid; Chin Cheow Keat
A method to determine six organochlorine and three pyrethroid pesticides in grape, orange, tomato, carrot and green mustard based on solvent extraction followed by solid phase extraction (SPE) clean-up is described. The pesticides were spiked into the sample prior to analysis, extracted with ethyl acetate, evaporated and reconstituted with a solvent mixture of acetone:n-hexane (3:7). Three different sorbents (Strong Anion
Antioxidant activity of extracts of black sesame seed (Sesamum indicum L.) by supercritical carbon dioxide extraction.
Hu, Qiuhui; Xu, Juan; Chen, Shubing; Yang, Fangmei
Antioxidant activities of extracts derived from sesame seed by supercritical carbon dioxide (SC-CO(2)) extraction and by n-hexane were determined using alpha,alpha-diphenyl-beta-picylhydrazyl (DPPH) radical scavenging and linoleic acid system methods. The highest extracted yield was given at 35 degrees C, 40 MPa, and a CO(2) flow rate of 2.5 mL min(-1) by an orthogonal experiment. The yields of extracts increased with increasing pressure, and yields at 40 and 30 MPa were higher than that by solvent extraction at 46.50%. Results from the linoleic acid system showed that the antioxidant activity follows the order: extract at 35 degrees C, 20 MPa > BHT > extract at 55 degrees C, 40 MPa > extract at 55 degrees C, 30 MPa > Trolox > solvent extraction > alpha-tocopherol. The SC-CO(2) extracts exhibited significantly higher antioxidant activities comparable to that by n-hexane extraction. The extracts at 30 MPa presented the highest antioxidant activities assessed in the DPPH method. At 20 MPa, the EC(50) increased with temperature, which indicated that the antioxidant activity was decreased in a temperature-dependent manner. The significant differences of antioxidant activities were found between the extracts by SC-CO(2) extraction and n-hexane. However, no significant differences were exhibited among the extracts by SC-CO(2) extraction. The vitamin E concentrations were also significantly higher in SC-CO(2) extracts than in n-hexane extracts, and its concentrations in extracts corresponded with the antioxidant activity of extracts. PMID:14969554
Excited-state Raman spectroscopy with and without actinic excitation: S1 Raman spectra of trans-azobenzene
NASA Astrophysics Data System (ADS)
Dobryakov, A. L.; Quick, M.; Ioffe, I. N.; Granovsky, A. A.; Ernsting, N. P.; Kovalenko, S. A.
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 S1 and S0 spectra of trans-azobenzene in n-hexane. The S1 spectra were also measured conventionally, upon n?* (S0 ? S1) actinic excitation. The results are discussed and compared to earlier reports.
Improved methodology for the simultaneous detection of the trichothecene mycotoxins deoxynivalenol and nivalenol in cereals
Toshitsugu Tanaka; Akihiko Hasegawa; Yukio Matsuki; Kenji Ishii; Yoshio Ueno
A simple and sensitive method has been developed for the analysis of two trichothecene mycotoxins (deoxynivalenol and nivalenol) in cereals. These toxins were extracted with acetonitrile\\/water (3:1), defatted with n?hexane and purified by a two?step Chromatographic procedure using Florisil and Sep?pak columns. The amounts of deoxynivalenol (DON) and nivalenol (NIV) in the column eluates were quantitated by gas chromatography with
Transport properties of nonelectrolyte liquid mixtures. VIII. Viscosity coefficients for toluene and for three mixtures of toluene + hexane from 25 to 100░C at pressures up to 500 MPa
J. H. Dymond; M. A. Awan; N. F. Glen; J. D. Isdale
Viscosity coefficients measured using a two-coil self-centering falling-body viscometer are reported for toluene and three binary mixtures of toluene + n-hexane at 25, 50, 75, and 100░C at pressures up to 500 MPa. The data for a given composition at different temperatures and pressures are correlated very satisfactorily by a plot of reduced viscosity eta * versus log V', where
Transport properties of nonelectrolyte liquid mixtures. VIII. Viscosity coefficients for toluene and for three mixtures of toluene + hexane from 25 to 100░C at pressures up to 500 MPa
J. H. Dymond; M. A. Awan; N. F. Glen; J. D. Isdale
Viscosity coefficients measured using a two-coil self-centering falling-body viscometer are reported for toluene and three binary mixtures of toluene + n-hexane at 25, 50, 75, and 100░C at pressures up to 500 MPa. The data for a given composition at different temperatures and pressures are correlated very satisfactorily by a plot of reduced viscosity ?* versus log V', where V'=VĘV0(TR)\\/V0(T)
Transport properties of nonelectrolyte liquid mixtures---V. Viscosity coefficients for binary mixtures of benzene plus alkanes at saturation pressure from 283 to 393 K
J. H. Dymond; K. J. Young
Viscosity coefficient measurements at saturation pressure are reported for benzene + n-hexane, benzene + n-octane, benzene + n-decane, benzene + n-dodecane, benzene + n-hexadecane, and benzene + cyclohexane at temperatures from 283 to 393 K. The characteristic parameter G in the Grunberg and Nissan equation 10765_2004_Article_BF00504187_TeX2GIFE1.gif ell neta = x_1 ell neta _1 + x_2 ell neta _2 + x_1
Bioavailability of selenium in the defatted dark muscle of tuna
M. Yoshida; M. Abe; K. Fukunaga; K. Kikuchi
The content and bioavailability of selenium (Se) in the dark muscle of tuna (DMT) were studied. Fluorometric analysis showed that DMT contained 2.0-4.7 ?g g Se. A large part of Se of the DMT was recovered in the dry powder of the defatted fraction prepared by successive treatment with acetone and n-hexane\\/ethanol. On trypsin digestion of the defatted DMT, release
Transport of C 6 isomers through ZSM-5 zeolite membranes
Stefan Sommer; Thomas Melin; John L. Falconer; Richard D. Noble
The separation of binary mixtures of hexane isomers using ZSM-5 zeolite membranes on porous stainless steel and alumina tubes was modeled for both vapor permeation and pervaporation. The fluxes and selectivities for single-component and mixture permeation of n-hexane, 3-methylpentane (3-MP), and 2,2-dimethylbutane (DMB) were described by combining two diffusion mechanisms. The flux through zeolite pores was modeled by Maxwell¢Stefan diffusion
Influence of Si\\/Al ratio on hexane isomers adsorption equilibria
Alexandre F. P. Ferreira; Marjo C. Mittelmeijer-Hazeleger; Alfred Bliek; Jacob A. Moulijn
In this work we aim to have a better knowledge of the influence of silica\\/alumina ratio (SAR) on the adsorption equilibrium of hexane isomers on MFI zeolites. With a manometric set-up coupled with a micro-calorimeter we did address adsorption properties and heats of adsorption of n-hexane, 2-methylpentane, 2,2-dimethylbutane and 2,3-dimethylbutane on three samples with different Si\\/Al ratio. The branched isomers
Extraction and clean-up procedure for analysis of organochlorine pesticide residues in ethoxylated lanolin
Luciana Polese; Miriam Sannomiya; Ana Paula de Oliveira Sader; Maria L·cia Ribeiro
In the present study an evaluation was made of a method for the determination of organochlorine pesticide residues in ethoxylated lanolin. Samples were homogenized with Celite, transferred to chromatographic columns, prepacked with silica gel deactivated to 10%. The pesticide elution was processed with n-hexane¢dichloromethane and the concentrated eluate was analyzed using gas¢liquid chromatography (GC) with electron capture detection (ECD). The
Reactions on ZSM-5-type zeolite catalysts
J. R. Anderson; K. Foger; T. Mole; R. A. Rajadhyaksha; J. V. Sanders
Catalytic reactions and sorption measurements have been carried out with ZSM-5 and silicalite catalysts which are distinguished by variation in skeletal heteroatom concentration. The catalysts were used in both the hydrogen-exchanged and sodium-exchanged forms. Sorption measurements were made with the hydrocarbons n-hexane, 3-methylpentane, and 2,2-dimethyl-butane, and with the bases ammonia, n-butylamine, t-butylamine, and 4-methylquinoline. Catalytic reactions were carried out on
Determination of ink photoinitiators in packaged beverages by gas chromatography¢mass spectrometry and liquid chromatography¢mass spectrometry
Gianni Sagratini; Giovanni Caprioli; Gloria Cristalli; Dario Giardinß; Massimo Ricciutelli; Rosaria Volpini; Yanting Zuo; Sauro Vittori
A new analytical method, using gas chromatography¢mass spectrometry (GC\\/MS) and liquid chromatography¢mass spectrometry (LC\\/MS) techniques, was developed for the determination in packaged food beverages of five ink photoinitiator residues: 2-isopropylthioxanthone (ITX), benzophenone, 2-ethylhexyl-4-dimethylaminobenzoate (EHDAB), 1-hydroxycyclohexyl-1-phenyl ketone (IRGACURE 184) and ethyl-4-dimethylaminobenzoate (EDAB). Samples were extracted from selected beverages (milk, fruit juices and wine) and relative packagings, using n-hexane and dichloromethane, respectively,
Trypanocidal, leishmanicidal and antifungal potential from marine red alga Bostrychia tenella J. Agardh (Rhodomelaceae, Ceramiales)
Rafael de FelĒcio; Sķrgio de Albuquerque; Maria Clßudia Marx Young; Nair Sumie Yokoya; Hosana Maria Debonsi
Specimens of the red alga Bostrychia tenella J. Agardh (Rhodomelaceae, Ceramiales) were collected from the SŃo Paulo coast and submitted to room temperature solvent extraction. The resulting extract was fractionated by partitioning with organic solvent. The n-hexane (BT-H) and dichloromethane (BT-D) fractions showed antiprotozoal potential in biological tests with Trypanosoma cruzi and Leishmania amazonensis and presented high activity in an
A new minor dimmeric ester from seeds of Cassia fistula L. (Leguminosae)
PatrĒcia Sartorelli; JoŃo Henrique G. Lago; Rodrigo L. O. R. Cunha; Rodrigo O. S. Kitamura; Maria Claudia M. Young
Bioactivity-guided fractionation of n-hexane phase from MeOH extract of the seeds of Cassia fistula L. (Leguminosae) yielded two bioactive substances against Cladosporium cladosporioides and C. sphaerospermum. After spectroscopic analysis, these compounds were characterised as the known benzyl 2-hydroxy-3,6-dimethoxybenzoate and its dimer dibenzyl 2,2?-dihydroxy-3,6,3?,6?-tetramethoxy-biphenyl-1,1?-dicarboxylate, which showed a new structural arrangement.
A new minor dimmeric ester from seeds of Cassia fistula L. (Leguminosae)
PatrĒcia Sartorelli; JoŃo Henrique G. Lago; Rodrigo L. O. R. Cunha; Rodrigo O. S. Kitamura; Maria Claudia M. Young
Bioactivity-guided fractionation of n-hexane phase from MeOH extract of the seeds of Cassia fistula L. (Leguminosae) yielded two bioactive substances against Cladosporium cladosporioides and C. sphaerospermum. After spectroscopic analysis, these compounds were characterised as the known benzyl 2-hydroxy-3,6-dimethoxybenzoate and its dimer dibenzyl 2,2?-dihydroxy-3,6,3?,6?-tetramethoxy-biphenyl-1,1?-dicarboxylate, which showed a new structural arrangement.
Isolation of anti-ulcerogenic sesquiterpene lactones from Centaurea solstitialis L. ssp. solstitialis through bioassay-guided fractionation procedures in rats
Erdem Yesilada; Ilhan G³rb³z; Erdal Bedir; Irem Tatli; Ikhlas A. Khan
The fresh spiny flowers of Centaurea solstitialis ssp. solstitialis (CSS) are used for the treatment of peptic ulcers in Turkey. Ethanol (80%) extract of CSS exhibited significant anti-ulcerogenic effect on the ethanol-induced ulcerogenesis model in rats. The ethanol extract was further fractionated by successive solvent extractions with n-hexane, chloroform, ethyl acetate and n-butanol. All fractions showed significant anti-ulcerogenic activity, however,
Composite MOF foams: the example of UiO-66/polyurethane.
Pinto, Moisķs L; Dias, Sandra; Pires, JoŃo
Composite MOF foams were prepared using a direct synthesis of UiO-66 over a polyurethane foam template. Under optimized conditions, the composite materials maintained the macrostructure and flexibility of the polyurethane foam, and exhibited the microporosity, high surface area, and adsorption properties of the UiO-66. The composite MOF foam has hierarchical porosity and high adsorption capacity for benzene and n-hexane, maintaining more than 70% of the adsorption capacity of the UiO-66. PMID:23537010
Evaluation of the antioxidant activity of Ruellia tuberosa
Fu-An Chen; An-Bang Wu; Pochuen Shieh; Daih-Huang Kuo; Chi-Ying Hsieh
The antioxidant activity of Ruellia tuberosa L. (Acanthaceae) was investigated by the 2,2-diphenyl-1-picrylhydrazyl (DPPH) free radical-scavenging assay and the hydrogen peroxide-induced luminol chemiluminescence assay. The methanolic extract (ME) and its four fractions of water (WtF), ethyl acetate (EaF), chloroform (CfF), and n-hexane (HxF) were prepared and then subjected to antioxidant evaluation. The results of both methods revealed that R. tuberosa
A chemical extraction method for mimicking bioavailability of polycyclic aromatic hydrocarbons to wheat grown in soils containing various amounts of organic matter
Shu Tao; Fuliu Xu; Wenxin Liu; Yanhong Cui; Raymond M. Coveney, Jr. [Peking University, Beijing (China). Laboratory for Earth Surface Processes, College of Environmental Sciences
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.
R³ckstandsanalyse von Chlorkohlenwasserstoffen in Humanknochenmark durch hochaufl÷sende Gas-Chromatographie mit Elektroneneinfang-Detektor
S. Dmochewitz; K. Ballschmiter
In human bone marrow, a tissue with a high content of fat, the following organochlorine copounds were identified: a-, ▀- and ?-hexachlorocyclohexane (HCH\\/BHC), hexachlorobenzene (HCB), 4,4'-DDT, 4,4'-DDE, a complex pattern of polychlorinated biphenyls (PCB) and traces of dieldrin and heptachloroepoxide. The chlorinated hydrocarbons, as well as the lipids, were extracted with a mixture of n-hexane, acetone and methanol in a
Separation and identification of some chlorinated hydrocarbon insecticides and herbicides by two-dimensional thin-layer chromatography
V. M. Adamovi?
A simple and rapid procedure for the two-dimensional TLC separation and identification of some chlorinated insecticides and herbicides is described. The separation is carried out on silica gel G with the following solvent systems: a) benzene-glacial acetic acid-n-hexane and b) petroleum fraction b.p. 80¢100░C. The identification is achieved by spraying the chromatogram with diphenylamine and irradiating with U.V. light. The
Enthalpies of dissolution of n-alkanes in a mixture of methanol-formamide
NASA Astrophysics Data System (ADS)
Batov, D. V.; Kustov, A. V.; Antonova, O. A.; Smirnova, N. L.
The enthalpies of dissolution of n-hexane, n-octane, and n-decane are determined thermochemically under standard conditions to describe nonspecific solvation in a mixed solvent of methanol-formamide. Experimental data are matched with the values obtained using model calculations. It is found that the differences between the experimental and calculated enthalpies of dissolution in the region with a high content of formamide could be due to the preferable solvation of n-alkanes by methanol.
Natural and man-made sea slicks in the North Sea investigated by a helicopter-borne 5-frequency radar scatterometer
H. H³hnerfuss; W. Alpersj; H. Dannhauer; M. Gadej; P. A. Lange; V. Neumann; V. Wismannh
In April 1994 natural sea slicks and five man-made slicks, which were spread as a pure substance and from two different spreading solvents, n-hexane and ethanol, respectively, were overflown by a helicopter carrying a five-frequency multi-polarization radar scatterometer, the so-called Heliscat. For the first time, natural sea slicks were successfully simulated by spreading hexadecanoic acid methyl ester (palmitic acid methyl
A new minor dimmeric ester from seeds of Cassia fistula L. (Leguminosae).
Sartorelli, PatrĒcia; Lago, JoŃo Henrique G; Cunha, Rodrigo L O R; Kitamura, Rodrigo O S; Young, Maria Claudia M
Bioactivity-guided fractionation of n-hexane phase from MeOH extract of the seeds of Cassia fistula L. (Leguminosae) yielded two bioactive substances against Cladosporium cladosporioides and C. sphaerospermum. After spectroscopic analysis, these compounds were characterised as the known benzyl 2-hydroxy-3,6-dimethoxybenzoate and its dimer dibenzyl 2,2'-dihydroxy-3,6,3?,6?-tetramethoxy-biphenyl-1,1'-dicarboxylate, which showed a new structural arrangement. PMID:21756186
Cottonseed extraction with a new solvent system: Isohexane and alcohol mixtures
M. S. Kuk; R. J. Hron
A solvent system, consisting of isohexane and 5 to 25% alcohol, either ethanol (EtOH) or isopropyl alcohol (IPA), was tested\\u000a for extracting gossypol and oil from cottonseed. The test results indicate that this new solvent system not only is effective\\u000a in removing free and total gossypol but also is as efficient as n-hexane when extracting oil. The amino acid analysis
A validated chiral HPLC method for the determination of mebeverine HCl enantiomers in pharmaceutical dosage forms and spiked rat plasma
Mahasen A. Radwan; Heba H. Abdine; Hassan Y. Aboul-Enein
A new, precise, simple and accurate HPLC method was developed for the first time to separate and determine mebeverine enantiomers. Enantiomeric resolution was achieved on a cellulose Tris (3,5-dimethylphenyl carbamate) column known as Chiralcel OD, with UV detection at 263 nm. The mobile phase consisted of n-hexane, isopropyl alcohol and triethylamine (90:9.9:0.1 v\\/v\\/v). Sample run time was 18 min. On
Pyrene-POSS nanohybrid as a dispersant for carbon nanotubes in solvents of various polarities: its synthesis and application in the preparation of a composite membrane
In this study we report the preparation of nanohybrid dispersant molecules based on pyrene and polyhedral oligomeric silsesquioxanes for non-covalent functionalization of multi-walled carbon nanotubes (MWCNTs). The prepared dispersant improves the dispersion of MWCNTs in organic solvents with very different polarities such as tetrahydrofuran, toluene, and n-hexane. The functionalized MWCNTs were used to introduce conductivity into polydimethylsiloxane membranes which can be used for electrostatic discharge applications. PMID:22676373
Application of preparative high-speed counter-current chromatography\\/preparative high-performance liquid chromatography mode in rapid separation of saponins
Shun Yao; Jianguang Luo; Xuefeng Huang; Lingyi Kong
Combined with preparative high-performance liquid chromatography, high-speed counter-current chromatography was employed for isolation and purification of saponins from Gypsophila paniculata L. n-Hexane¢n-butanol¢methanol¢0.02% TFA (1:9:1:9, v\\/v) was employed as solvent system and 210nm was chosen as the wavelength of ultraviolet detection for the first time. The research tried to compare HSCCC with prep-HPLC, and further integrated their advantages to improve separation
Constitutional Dynamic Chemistry-based New Concept of Molecular Beacons for High Efficient Development of Fluorescent Probes.
Chang, Xingmao; Yu, Chunmeng; Wang, Gang; Fan, Jiayun; Zhang, Jianyun; Qi, Yanyu; Liu, Kaiqiang; Fang, Yu
Inspired by the concept of constitutional dynamic chemistry, we propose a new and well-adaptable strategy for developing molecular beacon (MB)-like fluorescent probes. To demonstrate the strategy, we synthesized and used an amino group containing pyrenyl derivative of cholesterol (CP) for the construction of new fluorescent probes with EDTA and sulfuric acid. The probes as created were successfully used for n-hexane purity checking and Ba(2+)and Pb(2+)sensing, respectively. PMID:25985384
Induction of growth hormone by the roots of Astragalus membranaceus in pituitary cell culture
Chungsook Kim; Hyekyung Ha; Jin Sook Kim; Yun Tai Kim; Sun-Chang Kwon; Sie Won Park
The traditional Asian medicinal herb, roots ofAstragalus (A.) membranaceus (Leguminosae), is used for many purposes, some of which are purported to stimulate the release of growth hormonein vivo. Extracts ofA. membranaceus were tested to determine whether they stimulate the release of growth hormone in rat pituitary cell culture.A. membranaceus was extracted sequentially with 80% ethanol (fraction A),n-hexane (fraction B); the
Determination of lorazepam in plasma from children by high-performance liquid chromatography with UV detection
Simon N. Muchohi; Kenneth Obiero; Gilbert O. Kokwaro; Bernhards R. Ogutu; Isaiah M. Githiga; Geoffrey Edwards; Charles R. J. C. Newton
A simple, sensitive, selective, and reproducible reversed-phase high-performance liquid chromatographic (HPLC) method with UV detection was developed for the determination of lorazepam (LZP) in human plasma, using oxazepam (OZP) as internal standard. LZP and OZP were extracted from alkalinized (pH 9.5) spiked and clinical plasma samples using a single step liquid¢liquid extraction with a mixture of n-hexane¢dichloromethane (70:30%; v\\/v). Chromatographic
Establishment of a liquid chromatographic\\/mass spectrometry method for quantification of tetrandrine in rat plasma and its application to pharmacokinetic study
Naining Song; Shaoyu Zhang; Quansheng Li; Changxiao Liu
A rapid and sensitive liquid chromatography-tandem mass spectrometric method (LC\\/MS\\/MS) for the determination of tetrandrine in rat plasma has been developed, fully validated and successfully applied to pharmacokinetic study in Sprague¢Dawley (SD) rats after a single oral administration. Sample preparation involves a liquid¢liquid extraction with n-hexane¢dichlormethane (65:35, containing 1% 2-propanol isopropyl alcohol, v\\/v). Tetrandrine and brodimoprim (internal standard) were well
Determination of nifedipine in human plasma by ultra performance liquid chromatography¢tandem mass spectrometry and its application in a pharmacokinetic study
Dan Wang; Kun Jiang; Shuyan Yang; Feng Qin; Xiumei Lu; Famei Li
A fast, sensitive and selective ultra performance liquid chromatography¢tandem mass spectrometric (UPLC¢MS\\/MS) method was developed for the determination of nifedipine in human plasma. Nitrendipine was used as the internal standard. The sample preparation employed liquid¢liquid extraction with a mixture of n-hexane¢diethyl ether (1:3, v\\/v). Chromatographic separation was performed on an ACQUITY UPLCÖ BEH C18 column. The mobile phase was composed
Solidphase extraction and GC-MS analysis of potentially genotoxic cleavage products of ?-carotene in primary cell cultures
G. Martano; C. Vogl; E. Bojaxhi; N. Bresgen; P. Eckl; H. Stutz
A validated method for the simultaneous determination of prominent volatile cleavage products (CPs) of ?-carotene in cell\\u000a culture media has been developed. Target CPs comprised ?-ionone (?-IO), cyclocitral (CC), dihydroactinidiolide (DHA), and\\u000a 1,1,6-trimethyltetraline (TMT). CPs were extracted by solid-phase extraction applying a phenyl adsorbent, eluted with 10%\\u000a (v\\/v) tetrahydrofuran in n-hexane, and identified and quantified by gas chromatography-mass spectrometry with
Simple Preparative Isolation of Salvinorin A from the Hallucinogenic Sage, Salvia divinorum, by Centrifugal Partition Chromatography
Osamu Shirota; Kumi Nagamatsu; Setsuko Sekita
A simple procedure was developed to isolate salvinorin A from the hallucinogenic sage, Salvia divinorum, by means of centrifugal partition chromatography (CPC) using n?hexane¢dichloromethane¢methanol¢water (8:8:9:2, v\\/v) as a two?phase solvent system. The upper phase (organic phase) of the two?phase solvent system was used as the stationary phase for CPC separation. About 100Āmg of salvinorin A was obtained from ca. 2.5Āg
Role of rhenium and sulfur in platinum-based hydrocarbon-conversion catalysts
P. Biloen; J. N. Helle; H. Verbeek; F. M. Dautzenberg; W. M. H. Sachtler
The effect of sulfiding on the structure and the activity of silica-supported platinum, rhenium, and platinum\\/rhenium was studied by ESCA, X-ray diffraction, adsorption and IR spectroscopy of carbon monoxide and hydrogen, and the activity and selectivity for n-hexane hydrogenolysis, isomerization, and aromatization at 200┬░Ōü╗ŌüĄ┬░┬░sup 0\\/C. The platinum catalyst had a low-temperature (approx. 350┬░C) activity maximum for cracking, isomerization, and aromatization
Sources of Organic Contaminants in Solvents and Implications for Geochemistry and Environmental Forensics: An Example from Local Vendors in Nigeria
Bassey O. Ekpo; Orok E. Oyo-Ita; Daniel R. Oros; Bernd R. T. Simoneit
Two solvents, n-hexane and petroleum ether, commonly used for extract analysis of geological and environmental samples and purchased from chemical suppliers in Nigeria, were analyzed using gas chromatography-mass spectrometry for quantitative determination of organic background contaminants. Series of n-alkanes and n-alk-1-enes in the carbon number range of nC16¢nC26, the latter with an even predominance (Cmax 16 and 18) were observed.
Semimicro solvent extraction as a rapid and efficient preconcentration technique for the determination of n-alkanes in oil-contaiminated water and soil samples by capillary gas chromatography
M. A. Farajzadeh; A. A. Matin
SummaryĀĀIn this study, a rapid and efficient semi-micro extraction procedure is presented for the extraction of some higher n-alkanes\\u000a from water and soil samples. In the case of water samples n-hexane was used as the organic phase in a phase volume ratio (volume\\u000a of aqueous phase\\/volume of organic phase) higher than 285, while in the case of soil samples, extraction
GC¢MS analysis of essential oil of some commercial Fennel teas
A. R. Bilia; G. Flamini; V. Taglioli; I. Morelli; F. F. Vincieri
Fennel teas were prepared by classical infusion or microwave decoction of unbroken and crushed fruits, three pre-packaged teabags and two instant teas. Their volatile constituents were obtained by extraction with n-hexane and analysed by gas chromatography (GC) and gas chromatography\\/mass spectrometry (GC¢MS), using two columns with stationary phases of different polarity. Of the constituents 85¢95% were identified on the basis
Isolation and purification of honokiol and magnolol from cortex Magnoliae officinalis by high-speed counter-current chromatography
Xiao Wang; Yuqiang Wang; Yanling Geng; Fuwei Li; Chengchao Zheng
High-speed counter-current chromatography was used to isolate and purify honokiol and magnolol from cortex Magnoliae Officinalis (Magnolia officinalis Rehd. et Wils.), a plant used in the traditional Chinese medicine. A crude sample, 150mg, was successfully separated with a two-phase solvent system composed of n-hexane¢ethyl acetate¢methanol¢water (1:0.4:1:0.4, v\\/v), and the fractions were analyzed by high-performance liquid chromatography. The separation produced 80
Simultaneous determination of lincomycin and virginiamycin M 1 in swine muscle, liver and kidney by liquid chromatography¢electrospray ionization tandem mass spectrometry
Della W. M Sin; Clare Ho; Y. C Wong; S. K Ho; Alec C. B Ip
A simple, selective and sensitive method for simultaneous determination of lincomycin (LCM) and virginiamycin M1 (VGM) in swine muscle and organs using liquid chromatography with electrospray ionization tandem mass spectrometry is presented. Acetonitrile was used to extract the analytes from the samples. Lipids in the extracts were removed by liquid¢liquid partition with n-hexane. Analytes in the purified acetonitrile extracts were
Determination of diquat and paraquat in olive oil by ion-pair liquid chromatography¢electrospray ionization mass spectrometry (MRM)
MarĒa A. AramendĒa; V. Borau; Fernando Lafont; Alberto Marinas; Josķ M. Marinas; Josķ M. Moreno; Juan M. Porras; Francisco J. Urbano
For the first time a method for determination of herbicides diquat (DQ) and paraquat (PQ) in olive oil was developed utilising liquid chromatography¢electrospray ionization mass spectrometry (MRM). n-Hexane\\/10mM HFBA aqueous solution partitioning was used as the extraction method. Separation was carried out in an Xterra C8 column (100ū21mm, 3?m), using the gradient mode. Solvent A was a HFBA aqueous solution
Extent of the participation of lattice oxygen from ?-MnO 2 in VOCs total oxidation: Influence of the VOCs nature
Caroline Cellier; Valķrie Ruaux; Christophe Lahousse; Paul Grange; Eric M. Gaigneaux
Investigation of the total oxidation of n-hexane and trimethylamine as well as extensive characterizations of the catalyst after tests have been coupled to identify the mechanism of oxidation involved over a very active ?-MnO2 catalyst. This work shows that the extent of the catalyst reduction, which is a consequence of the Mars and van Krevelen redox mechanism, depends on the
The study of shea butter. VI: The extraction of shea butter
A. Kar; H. C. Mital
Shea butter has been extracted from the seeds of the shea tree,B. parkii, with various organic solvents. Petroleum ether (40░¢60░C),n-hexane, chloroform, and benzene extracted 32%¢38% of fat and 8¢9 mg% of vitamin E. These solvents, particularly petroleum ether andn-hexane, can be used for the production of shea butter that is free from any oxidized fat and coloring impurities.
Microemulsion phase behavior of anionic-cationic surfactant mixtures: Effect of tail branching
A. Upadhyaya; E. J. Acosta; J. F. Scamehorn; D. A. Sabatini
This research evaluated middle-phase microemulsion formation by varying the mole ratio of anionic and cationic surfactants\\u000a in mixtures with four different oils (trichloroethylene, n-hexane, limonene, and n-hexadecane). Mixtures of a double-tailed anionic surfactant (sodium dihexyl sulfosuccinate, SDHS) and an unbalanced-tail\\u000a (i.e., doubletailed with tails of different length) cationic surfactant (benzethonium chloride, BCl) were able to form microemulsions\\u000a without alcohol addition.
Hydrogen effect on hydrocarbon reactions over bulk tungsten carbide
Zhuang, Yiping; Frennet, A. [Universite Libre de Bruxelles (Belgium)] [Universite Libre de Bruxelles (Belgium)
The reactions of five hydrocarbon molecules (n-hexane, 3-methylpentane, 2,2-dimethylbutane, 2,3-dimethylbutane, and methylcyclopentane) were studied as a function of hydrogen pressure ranging from 60 to 680 Torr over bulk tungsten carbide prepared by direct carburisation of WO{sub 3} in a 20% CH{sub 4}/H{sub 2} flow. The sample was activated in H{sub 2} at 1073 K for 5 h before the reactions. No significant deactivation was observed during reactions. Olefins represent an important group of the products. Increasing hydrogen pressure leads to a decrease of isomerisation rate in n-hexane, 3-methylpentane, and 2,2-dimethylbutane reactions, while a maximum rate was observed in 2,3-dimethylbutane reactions. Irrespective of the hydrogen pressure, the isomerisation rate is always larger than the rate of methylcyclopentane ring opening. The formation rate of the products resulting from single hydrogenolysis exhibits a maximum on increasing hydrogen pressure; the deethylation rate is faster than the demethylation and depropylation rates by a factor of 3 to 10 at the hydrogen pressure corresponding to the maximum rate. The exposure of the catalyst to oxygen leads to a fast decrease of the hydrogenolysis rate and a high selectivity to the isomerisation products in n-hexane reactions. The results confirm that the hydrogenolysis takes place on a tungsten carbide phase and the isomerisation on a tungsten oxycarbide or a tungsten oxide phase through a bond-shift mechanism. 30 refs., 12 figs.
Asparagopsis armata and Sphaerococcus coronopifolius as a natural source of antimicrobial compounds.
Pinteus, Susete; Alves, Celso; Monteiro, Hugo; Ara·jo, Ernesto; Horta, Andrķ; Pedrosa, Rui
Methanol, n-hexane and dichloromethane extracts of twelve marine macro-algae (Rhodophyta, Chlorophyta and Heterokontophyta divisions) from Peniche coast (Portugal) were evaluated for their antibacterial and antifungal activity. The antibacterial activity was evaluated by disc diffusion method against Bacillus subtilis (gram positive bacteria) and Escherichia coli (gram negative bacteria). Saccharomyces cerevisiae was used as a model for the antifungal activity by evaluating the growth inhibitory activity of the extracts. The high antibacterial activity was obtained by the Asparagopsis armata methanolic extract (10 mm-0.1 mg/disc), followed by the Sphaerococcus coronopifolius n-hexane extract (8 mm-0.1 mg/disc), and the Asparagopsis armata dichloromethane extract (12 mm-0.3 mg/disc) against Bacillus subtilis. There were no positive results against Escherichia coli. Sphaerococcus coronopifolius revealed high antifungal potential for n-hexane (IC50 = 40.2 Ąg/ml), dichloromethane (IC50 = 78.9 Ąg/ml) and methanolic (IC50 = 55.18 Ąg/ml) extracts against Saccharomyces cerevisiae growth. The antifungal potency of the Sphaerococcus coronopifolius extracts was similar with the standard amphotericin B. Asparagopsis armata and Sphaerococcus coronopifolius reveal to be interesting sources of natural compounds with antimicrobial properties. PMID:25588525
In vitro antiprotozoal activity of extracts of five Turkish Lamiaceae species.
Kirmizibekmez, Hasan; Atay, Irem; Kaiser, Marcel; Yesilada, Erdem; Tasdemir, Deniz
The in vitro antiprotozoal activities of crude methanolic extracts from the aerial parts of five Lamiaceae plants (Salvia tomentosa, S. sclarea, S. dichroantha, Nepeta nuda subsp. nuda and Marrubium astracanicum subsp. macrodon) were evaluated against four parasitic protozoa, i.e. Trypanosoma brucei rhodesiense, T. cruzi, Leishmania donovani and Plasmodium falciparum. The cytotoxic potentials of the extracts on L6 cells were also evaluated. Melarsoprol, benznidazole, miltefosine, chloroquine and podophyllotoxin were used as reference drugs. All crude MeOH extracts showed antiprotozoal potential against at least three parasites, so they were dispersed in water and partitioned against n-hexane and chloroform to yield three subextracts that were screened in the same test systems. The n-hexane extract of N. nuda was the most active against T. brucei rhodesiense while the CHCl3 extracts of S. tomentosa and S. dichroantha showed significant activity against L. donovani. All organic extracts displayed in vitro antimalarial and moderate trypanocidal activities against T. cruzi with the n-hexane extract of S. sclarea being the most active against the latter. The extracts displayed low or no cytotoxicity towards mammalian L6 cells. PMID:22224291
Antidiabetic effect of Equisetum arvense L. (Equisetaceae) in streptozotocin-induced diabetes in male rats.
Safiyeh, Soleimani; Fathallah, Fathiazar Baijani; Vahid, Nejati; Hossine, Nazemiyeh; Habib, Shojaei Sadee
In view of alleged antidiabetic potential effect of the methanol, n-hexan and dichloromethane extracts of Equisetum arvense of blood sugar and body weight in streptozotocin-induced (50 mg kg(-1), i.p. dissolved in normal saline) diabetic rats were investigated. The blood glucose lowering activity of the methanol, n-hexan and dichloromethane extracts was determined in steptozotocin-induced diabetic rats; after oral administration in doses of 50, 100, 250 and 500 mg kg(-1) daily for 5 weeks. The data was compare statistically using one-way ANOVA tukey test. The results showed that in different doses of methanolic extract, dichloromethane extract at doses of 50 and 250 mg kg(-1) and n-hexan extract (50 mg kg(-1)), blood sugar decreased significantly in comparison with the treatment and control groups of diabetic rats. Also the weights of methanolic-extract treatment group were higher than the other treatment groups. The present studies clearly indicate a significant antidiabetic effect with the methanolic extract of Equisetum arvense and lend support for its traditional usage. Further investigation on identification of the active principles and their mode of action are needed to unravel the molecular mechanisms involved in the observed effects. PMID:19086514
Potent ?-glucosidase inhibitors isolated from Ginkgo biloba leaves.
Sukito, Agus; Tachibana, Sanro
In vitro ?-glucosidase inhibitory activity of Ginkgo biloba leaves was investigated. The inhibitory activity of methanol extracts from yellow and green leaves was 13.8 and 40.1 ?g mL(-1), respectively. Each methanol extract was separated into its respective fraction by solvent-solvent extraction with n-hexane, chloroform, ethyl acetate and n-butanol. The n-hexane fractions (in both methanol extracts from green and yellow leaves) exhibited high ?-glucosidase inhibitory activity with IC50 values of 13.6 and 13.4 ?g mL(-1), respectively. Further fractionation of the n-hexane fractions by silica gel column chromatography gave the most active fraction which was identified as ginkgolic acid (C13:0) and a mixture (C13:0, C15:0, C15: 1, C17:1 and C17:2). Ginkgolic acid (C13:0) exhibited the highest ?-glucosidase inhibitory activity. This is the first study to successfully isolate ginkgolic acids as ?-glucosidase inhibitors. PMID:26027162
P-Glycoprotein inhibitory activity of lipophilic constituents of Echinacea pallida roots in a human proximal tubular cell line.
Romiti, Nadia; Pellati, Federica; Nieri, Paola; Benvenuti, Stefania; Adinolfi, Barbara; Chieli, Elisabetta
The N-hexane root extracts from Echinacea pallida, Echinacea angustifolia and Echinacea purpurea were evaluated for inhibition of the multidrug transporter P-glycoprotein (Pgp) activity, the product of the ABCB1 gene, involved in cancer multidrug resistance (MDR) and in herb-drug or drug-drug interactions. The biological assay was performed using the human proximal tubule HK-2 cell line that constitutively expresses ABCB1. The N-hexane extracts of all three species reduced the efflux of the Pgp probe calcein-AM from HK-2 cells two-fold in a concentration-dependent manner, and E. pallida was found to be the most active species. For the first time, two polyacetylenes and three polyenes, isolated from the N-hexane extract of E. pallida roots by a bioassay-guided fractionation, were found to be able to reduce Pgp activity. Pentadeca-(8 Z,13 Z)-dien-11-yn-2-one was the most efficient compound, being able to decrease the calcein-AM efflux about three-fold with respect to the control at 30 microg/mL. PMID:18425719
Antiinflammatory effect of Curcuma xanthorrhiza Roxb, and its active principles.
Ozaki, Y
The rhizomes of Curcuma xanthorrhiza Roxb, are used in Indonesian folk medicine as cholagogues, aromatic stomachics, analgesics, a rheumatic remedy, etc. The present study was carried out to elucidate the antiinflammatory effect of the methanol extract obtained from these rhizomes and its active principles. The methanol extract was partitioned between ether and water, and then the ether-soluble fraction was extracted with n-hexane. The n-hexane-soluble fraction was chromatographed (fr. I-IV), fr. II was rechromatographed (fr. V-VII), and then fr. V was rechromatographed (fr. VIII-X) by silica gel column chromatography. The antiinflammatory activity of these fractions was investigated on carrageenin-induced edema in rats and acetic acid-induced vascular permeability as well as the writhing symptom in mice. The methanol extract (p.o.) showed both an antiinflammatory activity and an analgesic activity and these activities shifted successively to the ether-soluble fraction, the n-hexane-soluble fraction, fr. II, V and IX. The chemical structure of fr. IX was identified as germacrone. These results suggest that the antiinflammatory action of Curcuma xanthorrhiza is the result of the germacrone that it contains. PMID:2379278
Antiinflammatory effect of mace, aril of Myristica fragrans Houtt., and its active principles.
Ozaki, Y; Soedigdo, S; Wattimena, Y R; Suganda, A G
Mace which is the aril of the fruit of Myristica fragrans HOUTT, has been used in Indonesian folk medicine as aromatic stomachics, analgesics, a medicine for rheumatism, etc. The present study was carried out to elucidate the antiinflammatory effect of methanol extract obtained from Mace and its active principles. The methanol extract was extracted with ether, and then the ether soluble fraction was extracted with n-hexane. The n-hexane soluble fraction was fractionated by silica gel column chromatography (Fr-l-Fr-V), and the active principle was isolated from Fr-II by thin layer chromatography (Fr-VI-Fr-VII). The antiinflammatory activity of these fractions was investigated on carrageenin-induced edema in rats and acetic acid-induced vascular permeability in mice. All fractions and indomethacin were suspended in 2% C.M.C. solution and administered p.o. The methanol extract (1.5 g/kg), ether fraction (0.9 g/kg), n-hexane fraction (0.5 g/kg), Fr-II (0.19 g/kg) and Fr-VI (0.17 g/kg) showed a lasting antiinflammatory activity, and the potencies of these fractions were approximately the same as that of indomethacin (10 mg/kg). Fr-VI was determined to be myristicin. These results suggest that the antiinflammatory action of Mace is due to the myristicin that it contains. PMID:2487032
Functionalized hollow siliceous spheres for VOCs removal with high efficiency and stability.
Wang, Hongning; Tang, Mei; Zhang, Ke; Cai, Daofei; Huang, Weiqiu; Chen, Ruoyu; Yu, Chengzhong
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
Dielectric constant of liquid alkanes and hydrocarbon mixtures
NASA Technical Reports Server (NTRS)
Sen, A. D.; Anicich, V. G.; Arakelian, T.
The complex dielectric constants of n-alkanes with two to seven carbon atoms have been measured. The measurements were conducted using a slotted-line technique at 1.2 GHz and at atmospheric pressure. The temperature was varied from the melting point to the boiling point of the respective alkanes. The real part of the dielectric constant was found to decrease with increasing temperature and correlate with the change in the molar volume. An upper limit to all the loss tangents was established at 0.001. The complex dielectric constants of a few mixtures of liquid alkanes were also measured at room temperature. For a pentane-octane mixture the real part of the dielectric constant could be explained by the Clausius-Mosotti theory. For the mixtures of n-hexane-ethylacetate and n-hexane-acetone the real part of the dielectric constants could be explained by the Onsager theory extended to mixtures. The dielectric constant of the n-hexane-acetone mixture displayed deviations from the Onsager theory at the highest fractions of acetone. The dipole moments of ethylacetate and acetone were determined for dilute mixtures using the Onsager theory and were found to be in agreement with their accepted gas-phase values. The loss tangents of the mixtures exhibited a linear relationship with the volume fraction for low concentrations of the polar liquids.
The investigation of inhibiting quorum sensing and methicillin-resistant Staphylococcus aureus biofilm formation from Liriodendron hybrid.
Tan, Xiaojuan; Yang, Dongting; Yang, Guoxu; Chen, Jinhui; Dong, Wei; Shi, Jisen; Jia, Aiqun
The quorum sensing (QS) of pathogens has been found to affect their biofilm forming ability, making it a potential target for anti-microbial therapy. The present research aimed to evaluate the anti-QS activities of different extracts and isolated phytochemicals from Liriodendron hybrid barks and their roles in the inhibition of the growth and biofilm formation of methicillin-resistant Staphylococcus aureus (MRSA). The assays on the inhibition of QS by the five extracts (n-hexane, dichloromethane, ethyl acetate, acetone, and methanol) and eight isolated compounds were carried out by using both the indicator strains Chromobacrerium violaceum CV026 and C. violaceum ATCC12472. The in vitro effects of the five extracts and eight isolated compounds on MRSA biofilm were also preliminarily evaluated using crystal violet micro titer plate assays. The results suggested that the dichloromethane extract showed anti-QS and MRSA biofilm inhibitory activities and the n-hexane extract possessed only MRSA biofilm inhibitory effect. The dichloromethane extract could serve as a source for developing bacterial intervention strategies targeting microbial QS system. All eight isolated compounds showed no anti-QS and biofilm formation inhibiting activities. So further researches are still being required to purify and identify the compounds possessing anti-QS and biofilm inhibitory effects from the dichloromethane and n-hexane extracts. PMID:26004723
Diterpenoids and flavonoids from the fruits of Vitex agnus-castus and antioxidant activity of the fruit extracts and their constituents.
Hajd·, Zsuzsanna; Hohmann, Judit; Forgo, Peter; Martinek, Tamßs; Dervarics, Mßtķ; Zupk¾, Istvßn; Falkay, Gy÷rgy; Cossuta, Daniel; Mßthķ, Imre
From the n-hexane fraction of the fruits of Vitex agnus-castus, two labdane-type diterpenes, vitetrifolin B and C, were isolated by means of multiple chromatographic separations, together with the previously identified rotundifuran, vitexilactone and the sesquiterpene spathulenol. From the EtOAc fraction, eupatorin was identified for the first time, besides the known casticin, penduletin, vitexin and orientin. The n-hexane, EtOAc and MeOH-H(2)O fractions of the MeOH extract of Agni-casti fructus were subjected to in vitro antioxidant assays. The EtOAc extract displayed a significant concentration-dependent effect when tested by 1,1-diphenyl-2-picrylhydrasyl (DPPH) free radical assay (IC(50) = 68 microg/mL) and against the autooxidation of a standard rat brain homogenate (IC(50) = 14 microg/mL). The MeOH-H(2)O fraction was less active with 3643 microg/mL (DPPH test) and IC(50) = 125 microg/mL (rat brain homogenate), while the n-hexane phase proved to be inactive. The main flavonoid constituents of the EtOAc extract, casticin, vitexin and orientin were assayed for antioxidant activity and found that only casticin possesses a marked lipid peroxidation inhibitory effect (IC(50) = 0.049 mm) compared with that of the positive control ascorbic acid (IC(50) = 0.703 mm). PMID:17262892
Analysis of Benzo[a]pyrene in Vegetable Oils Using Molecularly Imprinted Solid Phase Extraction (MISPE) Coupled with Enzyme-Linked Immunosorbent Assay (ELISA)
Pschenitza, Michael; Hackenberg, Rudolf; Niessner, Reinhard; Knopp, Dietmar
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
Small-mass AMS radiocarbon analysis at Nagoya University
NASA Astrophysics Data System (ADS)
Minami, Masayo; Kato, Tomomi; Miyata, Yoshiki; Nakamura, Toshio; Hua, Quan
As part of the ongoing development at the AMS facility of the Center for Chronological Research at Nagoya University to radiocarbon (14C) analyze samples smaller than 0.5 mg carbon (mgC), a compact graphitization manifold has been built. Tests with various reference materials show it performs well for samples as small as 0.1 mgC. Preparation with this new system is compared with the performance of the older protocol for regular-sized samples. Furthermore, it is shown that the addition of Cu and Ag before and stepwise heating during sealed-tube combustion of samples with high S content improve the degree of conversion to CO2 without having to resort to special purification measures such as the use of Co3O4 + Ag reagent and an n-pentane/LN2 trap before graphitization.
Crossed-beam DC slice imaging of fluorine atom reactions with linear alkanes.
Shi, Yuanyuan; Kamasah, Alexander; Joalland, Baptiste; Suits, Arthur G
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. PMID:25978893
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.
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 ś10 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.
Fischer Tropsch synthesis in supercritical fluids. Quarterly technical progress report, April 1, 1995--June 30, 1995
Akgerman, A.; Bukur, D.B.
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.
Interstate couplings in the triplet manifold of 9-xanthone
NASA Astrophysics Data System (ADS)
Koyanagi, M.; Terada, T.; Nakashima, K.
Using a heat-pulse modulation technique, phosphorescence spectra of 9-xanthone have been studied in n-pentane at 77 and 2.1 K. The three legitimate phosphorescent levels with different lifetimes are detected at 25 751, 25 766, and 25 774 cm-1 above the zero-vibrational level of the ground state. The origin of these multiple levels is explained in terms of spin-orbit interaction superimposed on environmental electrostatic coupling between T1(??*) and T2(n?*). The two coupling constants obtained are: (for the spin-orbit coupling) ?<1??Hso?2?>? =15.70 cm-1 (?=x, ?=y or vice versa); (for environmental direct coupling) <1??Henv?2?> =3.14 cm-1 (?=x, y, or z). For comparison, the T?S phosphorescence excitation spectrum, measured in the same matrix, are in good agreement with the calculated ones.
Combustion of liquid sprays at high pressures
NASA Technical Reports Server (NTRS)
Shearer, A. J.; Faeth, G. M.
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.
Minutes of the tenth meeting of the centers for the analysis of thermal/mechanical energy conversion concepts
DiPippo, R.
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.
A Detailed Chemical Kinetic Reaction Mechanism for n-Alkane Hydrocarbons From n-Octane to n-Hexadecane
Westbrook, C K; Pitz, W J; Herbinet, O; Curran, H J; Silke, E J
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.
Catalyseur d'hydrocraquage Ó base de sulfure de NiMo dķposķ sur une zķolithe HEMT modifiķe
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.
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 zķolithe NH4EMT par une solution de (NH4)2SiF6 fournit un solide comportant une phase SiO2 amorphe intimement mķlangķe aux parties intactes de la zķolithe. Sur ce support acide EMT-Si, on a greffķ un sulfure de NiMo afin de prķparer un catalyseur bifonctionnel qui a ķtķ testķ dans les rķactions d'hydrogķnation du benzĶne et d'hydrocraquage du n-heptane. Ce catalyseur NiMo/EMT-Si s'avĶre plus actif en hydrogķnation que son analogue NiMo/HY, en raison d'une meilleure dispersion du sulfure de NiMo. Sur le solide EMT modifiķ, le sulfure se rķpartit Ó peu prĶs ķgalement entre les mķsopores internes et les fissures crķes dans les grains de zķolithe lors de l'insertion du sulfure de NiMo. Au contraire sur le support Y, une partie du sulfure est externe aux grains de zķolithe et inactive en catalyse. Le catalyseur NiMo/EMT-Si est aussi trouvķ plus actif que le NiMo/HY en hydrocraquage du n-heptane, et un peu plus sķlectif en isomĶres.
Helical substituted polyacetylene-derived fluorescent microparticles prepared by precipitation polymerization.
Huang, Huajun; Chen, Chunni; Zhang, Dongyue; Deng, Jianping; Wu, Youping
This article reports the first fluorescent microparticles (MPs, approximately 600 nm in diameter) constructed using helical substituted polyacetylene and prepared via a precipitation polymerization approach. The MPs judiciously combine this interesting helical conjugated acetylene, fluorescent material and polymeric particles in one entity. The monomer containing a dansyl group undergoes precipitation polymerization in butanone/n-heptane mixed solvent, with (nbd)Rh(+) B(-) (C6 H5 )4 as a catalyst. MPs with a regular morphology are formed in a high yield (>80 wt%). UV-vis spectroscopy demonstrates that the polymer chains making up the MPs adopt helical structures. The MPs show considerable fluorescence emission (?max , 500 nm; excited at 340 nm). Based on SEM and fluorescence images, the formation mechanism of the MPs is proposed. This methodology opens up new ways to prepare functional microstructured materials derived from substituted polyacetylenes, and may also result in opportunities for new practical applications of polyacetylene and its derivatives. PMID:24549744
Preparation and characterization of polyethylene glycol diacrylate microgels using electron beam radiation
Hamzah, Mohd Yusof [Makmal Nanoteknologi, Bahagian Teknologi Sinaran (Malaysia); Isa, Naurah Mat; Napia, Liyana M. Ali [ALURTRON, Bahagian Kemudahan Iradiasi, Malaysian Nuclear Agency, 43000, Kajang, Selangor (Malaysia)
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.
Extraction and separation of thorium(IV) from lanthanides(III) with room-temperature ionic liquids containing primary amine N{sub 1923}
Zuo, Y. [Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun 130022 (China); Graduate School of Chinese Academy of Sciences, Beijing (China); Chen, J.; Bai, Y.; Li, D.Q. [Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun 130022 (China)
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)
Characterization of four potential laser-induced fluorescence tracers for diesel engine applications.
Trost, Johannes; Zigan, Lars; Leipertz, Alfred; Sahoo, Dipankar; Miles, Paul C
Four potential laser-induced fluorescence (LIF) tracers, 1-phenyloctane, 1-phenyldecane, 1-methylnaphthalene, and 2-methylnaphthalene, are characterized for diesel engine applications. These tracers, embedded in the diesel primary reference fuels n-C??H?? and iso-C??H??, match the relevant physical properties of commercial diesel fuel much better than the commonly used toluene/iso-octane/n-heptane tracer-fuel system does. The temperature and pressure dependencies of the fluorescence intensities and spectra were measured in a flow cell in nitrogen for each candidate tracer molecule. The results show that the signal intensities of the methylnaphthalenes are about two orders of magnitude higher than for 1-phenyloctane and 1-phenyldecane and show a strong temperature but no pressure, dependence. An analysis of the fluorescence spectrum of 1-methylnaphthalene shows that it also can be used for two-color detection LIF thermometry by choosing appropriate optical filters. PMID:24513750
Direct numerical simulations of temporally developing turbulent reacting liquid-fueled jets
NASA Astrophysics Data System (ADS)
Shashank, Shashank; Pitsch, Heinz
Liquid fueled engines are ubiquitous in the transportation industry because liquid fuel minimizes the weight and volume of propulsion systems. The combustion that occurs in these engines is an inherently multi-physics process, involving fuel evaporation, reaction kinetics, and high levels of turbulence. A desire for high fidelity data that explains complex interaction between different physical mechanisms motivates the consideration of direct numerical simulation (DNS) as an investigation tool. In this study three-dimensional DNS of a reacting n-heptane liquid fueled temporal jet have been performed to study auto-ignition and subsequent burning in conditions that are representative of a diesel engine environment. In these simulations the continuous phase is described using an Eulerian representation whereas Lagrangian particle tracking is used to model the dispersed phase. The results of this study will demonstrate the importance of unsteady effects, and of accounting for the interaction between different modes of combustion, when simulating spray combustion.
Hydrocarbon ignition: Automatic generation of reaction mechanisms and applications to modeling of engine knock
Chevalier, C.; Warnatz, J. [Stuttgart Univ. (Germany). Inst. fuer Technische Verbrennung; Pitz, W.J.; Westbrook, C.K. [Lawrence Livermore National Lab., CA (United States)
A computational technique is described which automatically develops detailed chemical kinetic reaction mechanisms for large aliphatic hydrocarbon fuel molecules. This formulation uses the LISP language to apply general rules which identify the chemical species produced, the reactions between these species, and the elementary reaction rates for each reaction step. Reaction mechanisms for cetane (n-hexadecane) and most alkane fuels C{sub 7} and smaller are developed using this automatic technique, and detailed sensitivity analyses for n-heptane and cetane are described. These reaction mechanisms are then applied to calculation of knock tendencies in internal combustion engines. The model is used to study the influence of fuel molecule size and structure on knock tendency, to examine knocking properties of fuel mixtures, and to determine the mechanisms by which pro-knock and anti-knock additives change knock properties.
Adsorption and desorption behavior of asphaltene on polymer-brush-immobilized surfaces.
Higaki, Yuji; Hatae, Kaoru; Ishikawa, Tatsuya; Takanohashi, Toshimasa; Hayashi, Jun-ichiro; Takahara, Atsushi
The adsorption behavior of a model compound for surface-active component of asphaltenes, N-(1-hexylheptyl)-N'-(12-carboxylicdodecyl) perylene-3,4,9,10-tetracarboxylic bisimide (C5Pe), and detachment behavior of asphaltene deposit films for high-density polymer brushes were investigated. Zwitterionic poly(3-(N-2-methacryloyloxyethyl-N,N-dimethyl)ammonatopropanesulfonate (PMAPS) brushes and hydrophobic poly(n-hexyl methacrylate) (PHMA) brushes exhibit less C5Pe adsorption than poly(methyl methacrylate) (PMMA). The asphaltene deposit films on the PHMA brush detached in a model oil (toluene/n-heptane=1/4 (v/v)), and the asphaltene films on the PMAPS brush detached in water. The antifouling character was explained by the interface free energy for the polymer-brush/asphaltenes (?SA) and polymer-brush/toluene (?SO). PMID:25370500
Extraction kinetics of rare earth metals with 2-ethylhexyl phosphonic acid mono-2-ethylhexyl ester using a hollow fiber membrane extractor
Kubota, Fukiko; Goto, Masahiro; Nakashio, Fumiyuki [Kyushu Univ., Fukuoka (Japan); Hano, Tadashi [Oita Univ. (Japan)
A kinetic study concerning chemical complexation-based solvent extraction of rare earth metals with 2-ethylhexyl phosphonic acid mono-2-ethylhexyl ester dissolved as an extractant in n-heptane was carried out using a microporous hydrophobic hollow fiber membrane extractor. The effects of concentration of chemical species in aqueous and organic feed solutions on the apparent permeabilities of metal species for extraction and stripping, respectively, were investigated to clarify the permeation mechanism. From the experimental results it was predicted that the permeation rate is controlled by diffusion of the chemical species in aqueous and organic phases and by interfacial chemical reaction. The experimental data were analyzed by the diffusion model accompanied with an interfacial reaction, taking into account the velocity distributions of the aqueous and organic phases through the inner and outer sides of the hollow fiber.
Extraction of rare earth metals with 2-ethylhexyl phosphonic acid mono-2-ethylhexyl ester in the presence of diethylenetriaminepentaacetic acid in aqueous phase
Kubota, Fukiko; Goto, Masahiro; Nakashio, Fumiyuki [Kyushu Univ., Fukuoka (Japan)
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.
Soot agglomeration in isolated, free droplet combustion
NASA Technical Reports Server (NTRS)
Choi, M. Y.; Dryer, F. L.; Green, G. J.; Sangiovanni, J. J.
Under the conditions of an isolated, free droplet experiment, hollow, carbonaceous structures, called soot spheres, were observed to form during the atmospheric pressure, low Reynolds number combustion of 1-methylnaphthalene. These structures which are agglomerates composed of smaller spheroidal units result from both thermophoretic effects induced by the envelope flame surrounding each drop and aerodynamic effects caused by changes in the relative gas/drop velocities. A chemically reacting flow model was used to analyze the process of sootshell formation during microgravity droplet combustion. The time-dependent temperature and gas property field surrounding the droplet was determined, and the soot cloud location for microgravity combustion of n-heptane droplets was predicted. Experiments showed that the sooting propensity of n-alkane fuel droplets can be varied through diluent substitution, oxygen-index variations, and ambient pressure reductions.
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.
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.
Models for liquid-liquid partition in the system propylene carbonate-organic solvent and their use for estimating descriptors for organic compounds.
Karunasekara, Thushara; Poole, Colin F
Partition coefficients for varied compounds were determined for the organic solvent-propylene carbonate biphasic partition system where the organic solvent is n-heptane, isopentyl ether or 1-octanol. These partition coefficient databases are analyzed using the solvation parameter model facilitating a quantitative comparison of the propylene carbonate-based partition systems with other totally organic partition systems. Propylene carbonate is a weak to intermediate cohesive solvent, reasonably dipolar/polarizable and hydrogen-bond basic, and weak hydrogen-bond acidic. Propylene carbonate-organic solvent systems offer a complementary approach to other totally organic biphasic partition systems for sample preparation and descriptor measurements of compounds virtually insoluble or unstable in water. PMID:21208619
Supercritical droplet gasification experiments with forced convection
NASA Technical Reports Server (NTRS)
Litchford, Ron; Parigger, Chris; Jeng, San-Mou
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.
High-performance liquid chromatography of bile pigments: separation and characterization of the urobilinoids.
Bull, R V; Lim, C K; Gray, C H
The detailed analysis of faecal bile pigments by high-performance liquid chromatography is described. Non-aqueous reversed-phase systems with acetonitrile-dimethyl sulphoxide or acetonitrile-dimethyl sulphoxide-methanol as the mobile phase on C1, C8 or C18-bonded silica are used for the group separation of verdinoids, violinoids and urobilinoids. A silica column, with acetonitrile-water-tetraethylene-pentamine as mobile phase, separates the laevorotatory stercobilin (C33H46N4O6) and half-stercobilin (C33H44N4O6) from the optically inactive urobilin (C33H42N4O6). The diastereoisomers are resolved by converting the urobilinoids into their dimethyl esters before chromatography on a silica column with n-heptane-methyl acetate-methanol containing 1% of diethylamine as the solvent system. PMID:7320125
Solution-phase photochemistry of a [FeFe]hydrogenase model compound: Evidence of photoinduced isomerisation
Kania, Rafal; Hunt, Neil T. [Department of Physics, University of Strathclyde, SUPA, Glasgow G4 0NG (United Kingdom); Frederix, Pim W. J. M. [Department of Physics, University of Strathclyde, SUPA, Glasgow G4 0NG (United Kingdom); WestCHEM, Department of Pure and Applied Chemistry, University of Strathclyde, Glasgow G1 1XL (United Kingdom); Wright, Joseph A.; Pickett, Christopher J. [Energy Materials Laboratory, School of Chemistry, University of East Anglia, Norwich Research Park, Norwich NR4 7TJ (United Kingdom); Ulijn, Rein V. [WestCHEM, Department of Pure and Applied Chemistry, University of Strathclyde, Glasgow G1 1XL (United Kingdom)
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.
Investigation of spray characteristics from a low-pressure common rail injector for use in a homogeneous charge compression ignition engine
NASA Astrophysics Data System (ADS)
Lee, Kihyung; Reitz, Rolf D.
Homogeneous charge compression ignition (HCCI) combustion provides extremely low levels of pollutant emissions, and thus is an attractive alternative for future IC engines. In order to achieve a uniform mixture distribution within the engine cylinder, the characteristics of the fuel spray play an important role in the HCCI engine concept. It is well known that high-pressure common rail injection systems, mainly used in diesel engines, achieve poor mixture formation because of the possibility of direct fuel impingement on the combustion chamber surfaces. This paper describes spray characteristics of a low-pressure common rail injector which is intended for use in an HCCI engine. Optical diagnostics including laser diffraction and phase Doppler methods, and high-speed camera photography, were applied to measure the spray drop diameter and to investigate the spray development process. The drop sizing results of the laser diffraction method were compared with those of a phase Doppler particle analyser (PDPA) to validate the accuracy of the experiments. In addition, the effect of fuel properties on the spray characteristics was investigated using n-heptane, Stoddard solvent (gasoline surrogate) and diesel fuel because HCCI combustion is sensitive to the fuel composition. The results show that the injector forms a hollow-cone sheet spray rather than a liquid jet, and the atomization efficiency is high (small droplets are produced). The droplet SMD ranged from 15 to 30 Ąm. The spray break-up characteristics were found to depend on the fuel properties. The break-up time for n-heptane is shorter and the drop SMD is smaller than that of Stoddard solvent and diesel fuel.
Molecular dynamics simulation of water/BHDC cationic reverse micelles. structural characterization, dynamical properties, and influence of solvent on intermicellar interactions.
Agazzi, Federico M; Correa, N Mariano; Rodriguez, Javier
We report results obtained from molecular dynamics (MD) experiments of benzylhexadecyldimethylammonium chloride (BHDC) cationic reverse micelles (RMs). In particular we analyzed equilibrium and dynamical characteristics of water/BHDC RMs in pure benzene, at two different water/BHDC ratios (W0 = 5 and W0 = 10). The RMs appear as elliptical aggregates with eccentricities close to ?0.9. Analysis of the different spatial correlations reveals three different spatial domains in the RMs: a water inner pool, the surfactant interface, and the external solvent. The calculated accessible surface areas for the aqueous inner cores suggest a strong penetration of solvent molecules within the micellar interface domains. Comparison between the density profiles of both RMs shows an increment of the broadness in the distributions of all species at the interface, along with an increasing overlap between the tail segments of the surfactant and benzene molecules as one considers larger micelles. For the dynamical side, the rotational characteristic time scale for the confined water was found to be 1 order of magnitude larger than that of the bulk water. A similar effect was also observed for hydrogen bond dynamics. Both retardation effects diminish with the size of the aggregate. To the estimate the influence of the external solvent on the intermicellar interactions, free energy profiles for the coalescence process between RMs of similar size in pure benzene and in a n-heptane/benzene mixture were also investigated. The results indicate that the association process is facilitated by the presence of n-heptane in the external nonpolar phase. Comparison with previous theoretical and experimental results is also carried out. PMID:25068175
A computational investigation of diesel and biodiesel combustion and NOx formation in a light-duty compression ignition engine
Wang, Zihan; Srinivasan, Kalyan K.; Krishnan, Sundar R.; Som, Sibendu
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."
A comprehensive combustion model for biodiesel-fueled engine simulations
NASA Astrophysics Data System (ADS)
Brakora, Jessica L.
Engine models for alternative fuels are available, but few are comprehensive, well-validated models that include accurate physical property data as well as a detailed description of the fuel chemistry. In this work, a comprehensive biodiesel combustion model was created for use in multi-dimensional engine simulations, specifically the KIVA3v R2 code. The model incorporates realistic physical properties in a vaporization model developed for multi-component fuel sprays and applies an improved mechanism for biodiesel combustion chemistry. A reduced mechanism was generated from the methyl decanoate (MD) and methyl-9-decenoate (MD9D) mechanism developed at Lawrence Livermore National Laboratory. It was combined with a multi-component mechanism to include n-heptane in the fuel chemistry. The biodiesel chemistry was represented using a combination of MD, MD9D and n-heptane, which varied for a given fuel source. The reduced mechanism, which contained 63 species, accurately predicted ignition delay times of the detailed mechanism over a range of engine-specific operating conditions. Physical property data for the five methyl ester components of biodiesel were added to the KIVA library. Spray simulations were performed to ensure that the models adequately reproduce liquid penetration observed in biodiesel spray experiments. Fuel composition impacted liquid length as expected, with saturated species vaporizing more and penetrating less. Distillation curves were created to ensure the fuel vaporization process was comparable to available data. Engine validation was performed against a low-speed, high-load, conventional combustion experiments and the model was able to predict the performance and NOx formation seen in the experiment. High-speed, low-load, low-temperature combustion conditions were also modeled, and the emissions (HC, CO, NOx) and fuel consumption were well-predicted for a sweep of injection timings. Finally, comparisons were made between the results of biodiesel composition (palm vs. soy) and fuel blends (neat vs. B20). The model effectively reproduced the trends observed in the experiments.
Antioxidant Capacities, Phenolic Profile and Cytotoxic Effects of Saxicolous Lichens from Trans-Himalayan Cold Desert of Ladakh
Kumar, Jatinder; Dhar, Priyanka; Tayade, Amol B.; Gupta, Damodar; Chaurasia, Om P.; Upreti, Dalip K.; Arora, Rajesh; Srivastava, Ravi B.
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
Analgesic, anti-inflammatory and anti-pyretic activities of Caesalpinia decapetala
Parveen, Amna; Sajid Hamid Akash, Muhammad; Rehman, Kanwal; Mahmood, Qaisar; Qadir, Muhammad Imran
Introduction: In many pathological conditions, pain, inflammation and fever are interdependent to each other. Due to the use of synthetic drugs, many unwanted effects usually appear. Various studies have been conducted on Caesalpinia decapetala (C. decapetala) to evaluate its effects in the treatment of various diseases but no sufficient scientific literature is available online to prove its analgesic, anti-inflammatory and anti-pyretic activities. Methods: The analgesic, anti-inflammatory and anti-pyretic activities of 70% aqueous methanolic and n-hexane extracts of C. decapetala was evaluated using Swiss albino mice (20-30 g). Results: The results showed that aqueous methanolic extract of C. decapetala at the dose of 100 mg/kg exhibited significant (p< 0.05) activities in various pain models including acetic acid-induced writhing (18.4 ▒ 0.53), formalin-induced licking (275 ▒ 4.18) and hot plate method (2.3 ▒ 0.0328); whereas,Ā n-hexane extract showed its effects in acetic acid-induced writhing (20 ▒ 0.31), formalin-induced licking (293 ▒ 1.20) and hot plate method (2.224 ▒ 0.029) compared to the effects observed in control group animals. Similarly, the aqueous methanolic extract of C. decapetala after 2 h of treatment exhibited more significant anti-inflammatory (0.66 ▒ 0.06) and anti-pyretic (38.81 ▒ 0.05) activities compared to the control group animals. Conclusion: From the findings of our present study, we concluded that the aqueous methanolic extract of C. decapetala has stronger analgesic, anti-inflammatory and anti-pyretic effects than its n-hexane extract. Further studies are required to investigate the active constituents of C. decapetala that exhibit analgesic, anti-inflammatory and anti-pyretic activities. PMID:24790898
Cytotoxicity of some edible mushrooms extracts over liver hepatocellular carcinoma cells in conjunction with their antioxidant and antibacterial properties
Sadi, G÷khan; Emsen, Bu?rahan; Kaya, Abdullah; Kocaba?, Aytań; Ū?nar, Seval; Kartal, Deniz ?rtem
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
Antioxidant capacities, phenolic profile and cytotoxic effects of saxicolous lichens from trans-Himalayan cold desert of Ladakh.
Kumar, Jatinder; Dhar, Priyanka; Tayade, Amol B; Gupta, Damodar; Chaurasia, Om P; Upreti, Dalip K; Arora, Rajesh; Srivastava, Ravi B
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
Pharmacological and biological evaluation of extracts from Gratiola officinalis L. (Scrophulariaceae).
Ahmad, Mansoor; Muhammad, Noor; Mehjabeen; Jahan, Noor; Ahmad, Manzoor; Habib, Salman
The crude extract of Gratiola officinalis and its n-hexane, chloroform, ethyl acetate, n-butanol and aqueous fractions were subjected to biological (Brine Shrimp Bioassay, Insecticidal and Phytotoxicity/Cytotoxic) and neuropharmacological (Head dip, Open field Forced swimming test, Sodium pentothal induced sleep) activities. Results obtained in this study indicated that at high concentration dose (1000?g/ml), all test samples showed 60-95% phytotoxicity. In crude extract, n-butanol and aqueous fractions produced more than 85% phytotoxicity. While low concentration (10?g/ml) dose showed 25-28% phytotoxicity in all test samples. The crude extract was devoid of any effect against the growth of Callosbruchus analis and Tribolium castaneum and caused 10 mortality of Rhyzopertha dominica. n-Hexane, chloroform, ethylacetate, n-butanol and aqueous fractions caused 50, 30, 40, 10 and 20% mortality respectively of C. analis where as chloroform, ethyl-acetate, aqueous and crude extract, n-hexane, ethyl-acetate fractions also caused low mortality (10%) of Tribolium castaneum and Rhyzopertha dominica respectively. In cytotoxic assay at 1000?g/ml concentration, n-butanol fraction produced 36.7% and the crude extract produced 13.3% mortality of brine shrimp, its aqueous fraction was inactive at all concentrations. The results of head dip, open field, mobility time and Pentothal Na induced sleep indicated that crude extract, n-butanol and ethylacetate fractions of G. officinalis had mild sedative effect. However aqueous fraction was found to produce a significant decrease in motor activities and potentiated the duration of sleep. PMID:22713957
Two-step preparation of ginsenoside-Re, Rb 1, Rc and Rb 2 from the root of Panax ginseng by high-performance counter-current chromatography
Yijun Cheng; Min Zhang; Qionglin Liang; Ping Hu; Yiming Wang; Frank Wu Jun; Guoan Luo
A two-step counter-current chromatography (CCC) method was developed for the preparation of ginsenoside-Re, Rb1, Rc and Rb2 from ginseng with two solvent systems, methylene chloride¢methanol¢water¢isopropanol (6:2:4:3, v\\/v) and n-hexane¢n-butanol¢0.1% formic acid (0.7:3:4, v\\/v). The classical CCC mode was applied in the first separation step while the elution-extrusion counter-current chromatography (EECCC) in the second separation step. The preparation yielded 76.1mg, 137.0mg,
Iron carbonyl complexes from 2-[2,3-diaza-4-(2-thienyl)buta-1,3-dienyl]thiophene: N?N bond cleavage and cyclometalation
Chi-Jeh Lin; Wen-Shu Hwang; Michael Y Chiang
When thienyl Schiff base 1, derived from 2-formylthiophene and hydrazine, reacted with Fe2(CO)9 in n-hexane, three major complexes were obtained: (1) a diironhexacarbonyl complex with two 2-thienylmethylideneamido bridging ligands 2, which resulted from the ?N?N? bond cleavage of ligand 1; (2) a doubly cyclometalated di-?-di-(?1:?2-thienyl; ?1:?1(N))bis(hexacarbonyldiiron) complex (3); and (3) a cyclometalated (?-?1:?2-thienyl; ?1:?1(N))hexacarbonyldiiron complex (4). Molecular structures of compounds
A study of steam reforming of hydrocarbon fuels on Pd\\/ceria
X. Wang; R. J. Gorte
Differential steam-reforming rates were measured for methane, ethane, n-butane, n-hexane, 2,4-dimethylhexane, n-octane, cyclohexane, benzene, and toluene over 1wt.% Pd\\/ceria between 620 and 770K and were compared to rates observed on 1wt.% Pd\\/alumina and 1wt.% Pt\\/ceria. The H2O:C ratios at which stable rates were observed on Pd\\/ceria depended on the hydrocarbon, varying from less than 1:1 for methane to 3:1 for
The relationship of serum tocopherol and tocotrienol concentrations to the serum concentrations of lipids and lipoproteins in normocholesterolemic middle-aged men after consuming crude palm oil-rich dietsĀ
Peterson, Jeffery Scott
added to the contents of each tube. The tubes were vigorously shaken. The solution was extracted 3 times with 4 mL of n-hexane (Mallinckrodt Chemical, Inc. , Paris, KY) . For extraction, the tubes were shaken vigorously by hand. Then they were... fritted disk Buchner funnel (4-5. 5 ASTM) . The tocopherols and tocotrienols were eluted from the silica gel with 25-30 mL of chloroform/methanol (2:1) (chloroform, Fischer Scientific; methanol, Mallinckrodt Chemical) . The eluant was evaporated...
A new hydrochalcone from Miliusa sinensis.
Thuy, Tran Thi Thanh; Quan, Tran Duc; Anh, Nguyen Thi Hoang; Van Sung, Tran
A new dihydrochalcone 4',6'-dihydroxy-2',3',4-trimethoxydihydrochalcone (1) along with nine known compounds, pashanone (2), dihydropashanone (3), pinostrobin (4), 5-hydroxy-7,4'-dimethoxyflavanone (5), 5-hydroxy-6,7-dimethoxyflavanone (6), 5-hydroxy-7,8-dimethoxyflavanone (7), 24-methylencycloartane-3?,21-diol (8), liriodenine (9) and 3,5-dihydroxy-7,3',4'-trimethoxyflavone (10), were isolated from the extracts, exhibiting cytotoxic activity (n-hexane and ethyl acetate extracts) of Miliusa sinensis. The structure of (1) was elucidated by the analysis of spectral data (IR, HR-MS, EI-MS, 1D and 2D NMR). PMID:21859261
Enzymatic synthesis of sucrose octaacetate using a novel alkaline protease.
Li, Guiying; Cai, Yujie; Liao, Xiangru; Yin, Jing
Acylation of 0.5 g sucrose with 1.2 ml acetic anhydride was carried out in 2 ml two-solvent medium of anhydrous pyridine/n-hexane (1:1, v/v) using 0.2 g crude protease from Serratia sp. Sucrose octaacetate was the sole product and more than 90% sucrose was converted in 24 h at 30░C. The purity of sucrose octaacetate reached 100%, via a simple purification method of alcohol/water washing and centrifugation. PMID:21072559
Thermal non-oxidative aromatization of light alkanes catalyzed by gallium nitride.
Li, Lu; Mu, Xiaoyue; Liu, Wenbo; Kong, Xianghua; Fan, Shizhao; Mi, Zetian; Li, Chao-Jun
The thermal catalytic activity of GaN in non-oxidative alkane dehydroaromatization has been discovered for the first time. The origin of the catalytic activity was studied experimentally and theoretically. Commercially available GaN powders with a wurtzite crystal structure showed superior stability and reactivity for converting light alkanes, including methane, propane, n-butane, n-hexane and cyclohexane into benzene at an elevated temperature with high selectivity. The catalyst is highly robust and can be used repeatedly without noticeable deactivation. PMID:25336448
Effect of support on catalytic behavior of dispersed rhodium for hydrocarbon hydrogenolysesĀ
Khalifa, Amina Ahmed
- duction, selectivity of rhodium for n-hexane during hy- drogenolysis of methylcyclopentane (MCP) at 150'C in- creased in the order Rh/SiO = Rh/TiO = Rh/Ce02 2 2 Rh/La 0 = Rh/Eu20 . Overall activity for MCP con- version, on the other hand, increased... particles by partially reduced support. Overall selectivity behaviors for hydrogenolyses of MCP, n-butane, and isopentane in- dicate that the ease of C-C bond cleavages over rhodium is in the order of 1' -2 & 2' -2' & 2' -3' Io 30 ACKNOWLEDGEMENTS I...
Comparative analysis of intramolecular interactions in trans-stilbene and 1,4-distyrylbenzene
NASA Astrophysics Data System (ADS)
Kompaneets, V. V.; Vasil'eva, I. A.
We have analyzed the intensity distributions in fine-structure fluorescence and fluorescence excitation spectra of trans-stilbene in n-hexane at 4.2 K. Modeling the spectra by representing each of the vibronic transitions by a zero-phonon line and a phonon wing with certain parameters (widths, Debye-Waller factors) made it possible to determine relative intensities of vibronic transitions. The parameters of Franck-Condon and Herzberg-Teller interactions, which form the fine-structure spectra of stilbene, have been calculated and compared with previously obtained parameters of intramolecular interactions in 1,4-distyrylbenzene.
Surface silylation and pore structure development of silica aerogel composites from colloid and TEOS-based precursor
Chang-Yeoul Kim; A-Rum Jang; Byung-Ik Kim; Dong-Hack Suh
Flexible aerogel-fiber composites were prepared by silylation and ambient drying of colloidal silica and tetraethylorthosilicate\\u000a (TEOS)-based sol. After immersing glass fiber matrices into silica sol with colloid-based, colloid\\/TEOS-based, and TEOS-based\\u000a silica sol, it was surface-modified in a trimethylchlorosilane\\/n-hexane solution and heat-treated at 230Ā░C in ambient atmosphere. Surface silylation of silica aerogel synthesized from colloid\\u000a and TEOS-based silica sols showed different