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Carbon Number (carbon + number)
Selected AbstractsHigh-Performance Air-Stable n-Type Organic Transistors Based on Core-Chlorinated Naphthalene Tetracarboxylic DiimidesADVANCED FUNCTIONAL MATERIALS, Issue 13 2010Joon Hak Oh Abstract Core-chlorinated naphthalene tetracarboxylic diimides (NDIs) with fluoroalkyl chains are synthesized and employed for n-channel organic thin-film transistors (OTFTs). Structural analyses of the single crystals and thin films are performed and their charge-transport behavior is investigated in terms of structure,property relationships. NDIs with two chlorine substituents are shown to exhibit a herringbone structure with a very close ,-plane distance (3.3,3.4,Å), a large ,-stack overlap (slipping angle ca. 62°), and high crystal densities (2.046,2.091,g,cm,3). These features result in excellent field-effect mobilities of up to 1.43,cm2,V,1,s,1 with minimal hysteresis and high on,off ratios (ca. 107) in air. This is similar to the highest n-channel mobilities in air reported so far. Despite the repulsive interactions of bulky Cl substituents, tetrachlorinated NDIs adopt a slip-stacked face-to-face packing with an interplanar distance of around 3.4,Å, resulting in a high mobility (up to 0.44,cm2,V,1,s,1). The air-stability of dichlorinated NDIs is superior to that of tetrachlorinated NDIs, despite of their higher LUMO levels. This is closely related to the denser packing of the fluorocarbon chains of dichlorinated NDIs, which serves as a kinetic barrier to the diffusion of ambient oxidants. Interestingly, these NDIs show an optimal performance either on bare SiO2 or on octadecyltrimethoxysilane (OTS)-treated SiO2, depending on the carbon number of the fluoroalkyl chains. Their synthetic simplicity and processing versatility combined with their high performance make these semiconductors highly promising for practical applications in flexible electronics. [source] Use of TLC-FID and GC-MS/FID to examine the effects of migratory state, diet and captivity on preen wax composition in White-throated Sparrows Zonotrichia albicollisIBIS, Issue 4 2010RAYMOND H. THOMAS Preen wax is important for plumage maintenance and other functions. Its chemical composition is complex, and separating and quantifying its components, commonly by gas chromatography (GC), can be challenging. We present a simple analytical system consisting of thin-layer chromatography/flame ionization detection (TLC-FID) using a solvent system of 100% toluene to analyse the complex compound classes present in preen wax. We used GC and TLC-FID to investigate the effects of migratory status, diet and captivity on the preen wax composition of White-throated Sparrows Zonotrichia albicollis, and to measure the quantity of preen wax on the head, primary and tail feathers. White-throated Sparrows produced preen wax containing only monoesters regardless of migratory state. The monoesters contained several isomers consisting of homologous series of fatty alcohols (C10,C20) and fatty acids (C13,C19) esterified together in different combinations to form monoesters with total carbon numbers ranging from C23 to C38. Weighted average monoester carbon number was greater in captive birds than in wild birds and was greater in captives fed a formulated diet enriched with sesame oil than in birds fed the same diet enriched with fish oil. Captivity and migratory state also affected the complexity of the mixture of monoesters. There was significantly more preen wax on head feathers compared with primary and tail feathers. We suggest that among its many functions, preen wax may play a role in drag reduction by affecting the physical properties of feathers, and/or the fluid flow at their surfaces. [source] Detecting vegetable oil adulteration in hazelnut paste (Corylus avellana L.)INTERNATIONAL JOURNAL OF FOOD SCIENCE & TECHNOLOGY, Issue 3 2009Josep Serra Bonvehi Summary The possibilities of detecting hazelnut paste adulterated with refined and non-refined vegetable oils have been studied. Research was focussed mainly on peanut, high oleic-acid sunflower, corn and soybean oils which have a similar composition to hazelnut oil. The analytical procedures to detect fatty acid (FA), triacylglycerol (TAG) and tocopherol profiles as indicators of adulteration were determined. The better indicators experimentally determined were seven FA (palmitic, stearic, linoleic, linolenic, arachidonic, behenic and lignoceric acids) and different TAG with three unsaturated FA (the code letters used for FA are: P = C16:0; S = C18:0; O = C18:1; L = C18:2;; Ln = C18:3) (LLLn, LLL and OOO), two unsaturated FA (POL, PLL and SOO), and one unsaturated FA (PPL). As expected, when refined vegetable oils were added to hazelnut paste, the increment of stigmasta-3,5-diene allowed detection at levels of 2% oil added. Limits of detection were measured using standard and adulterated hazelnut with different amounts of non-refined vegetable oils added (5%, 10%, 20% and 30%). The distribution of tocopherols and tocotrienols is highly useful, except in the case of added sunflower oil. The differences between the experimental and theoretical values of the TAG with equivalent carbon number (,ECN) of 42 does not improve the detection limit of hazelnut paste adulterated with peanut or sunflower oils. Similarly, tocopherols usually added to refined vegetable oils as an antioxidant were also determined. [source] Production of zero trans Iranian vanaspati using chemical transesterification and blending techniques from palm olein, rapeseed and sunflower oilsINTERNATIONAL JOURNAL OF FOOD SCIENCE & TECHNOLOGY, Issue 3 2008Jamshid Farmani Summary Chemical transesterification and blending techniques were used for producing zero trans fats suitable for use as Iranian vanaspati. Triple blends of palm olein (POo), rapeseed (RSO) and sunflower oil (SFO) were subjected to two different treatments: (i) blending and then transesterification (BT) and (ii) transesterification of pure POo before blending with RSO and SFO (TB). The changes in slip melting point (SMP), solid fat content (SFC), carbon number (CN) triacylglycerol (TAG) composition, induction period (IP) of oxidation at 120 °C and IP of crystallisation at 20 °C of blends before and after treatments were investigated. Both BT and TB methods resulted in an increase in the CN48 TAG molecules, SMP and SFC, and a decrease in the IP of oxidation and crystallisation of initial blends. Samples made by TB method had higher CN48 TAG content, SMP, SFC and IP of oxidation, and lower IP of crystallisation than those made by BT method. Correlation between SFC at 20 °C and saturated fatty acid (SFA) content of the treated blends indicated that the SFA must be higher than 33.1% and 26.8% for BT and TB methods, respectively, to obtain fats suitable for use as vanaspati. [source] Determination of average carbon number of petroleum waxes by X-ray diffractionJOURNAL OF APPLIED CRYSTALLOGRAPHY, Issue 5 2008Sanat Kumar Eight petroleum waxes, both paraffin as well as microcrystalline, have been analysed by X-ray diffraction. The average carbon number has been estimated by the long-range ordering observed in the diffractograms of these waxes. The average carbon number has also been determined following the standard gas chromatographic (GC) method. The results obtained by X-ray diffractometry compare well with those obtained by the GC method. The former method also permits determination of the average carbon number of high melting point waxes, which is otherwise difficult using GC. [source] ZSM-11 membranes: Characterization and pervaporation performanceAICHE JOURNAL, Issue 2 2002Shiguang Li High-quality boron and aluminium-substituted ZSM-11 membranes were prepared on porous tubular supports to separate alcohols from water by pervaporation. The C1,C3 alcohols were preferentially separated from aqueous solutions through the B-ZSM-11 membrane, and the maximum flux was 1.7 kg/m2·h for a 5 wt.% methanol/water mixture. The alcohol fluxes decreased as the carbon number increased. The methanol/water separation selectivity decreased with pervaporation temperature, but other alcohol/water selectivities increased. All selectivities increased with decreasing alcohol feed concentration. In a range of 1 to 50 wt. % alcohol, the separation selectivities at 333 K for the C1,C3 linear alcohols were higher than vapor/liquid equilibrium selectivities. The highest selectivities observed for methanol/water, ethanol/water, 1-propanol/water, and 2-propanol/water were 28, 97, 34, and 26, respectively, at 1 wt. % alcohol feed concentrations. The separation selectivities were based on both preferential adsorption of alcohols and differences in diffusion rates. [source] Existence of a critical carbon number in the aging of a wax-oil gelAICHE JOURNAL, Issue 9 2001Probjot Singh A fundamental study was carried out to understand the aging (or hardening) of the wax-oil gels formed in the subsea pipelines during the flow of crude oil from offshore wells to shore. The aging process is a counterdiffusion phenomenon where there exists a critical carbon number (CCN), and wax molecules with carbon numbers greater than the CCN diffuse into the gel matrices and vice versa. Using a careful analysis of carbon number distributions of gel deposits, collected from a cold finger after various deposition time intervals, the CCN for the wax-oil system was obtained. A mathematical model, based on a modified version of UNIQUAC model, was developed to predict the CCN for wax-oil systems. The size of the interaction units for n-alkanes in the solid-phase UNIQUAC model was found to be a strong function of the mean carbon number in the solid phase. [source] AN UNUSUAL POLYUNSATURATED C-27 HYDROCARBON FROM THE MARINE DINOFLAGELLATE PYROCYSTIS LUNULAJOURNAL OF PHYCOLOGY, Issue 2001Article first published online: 24 SEP 200 Leblond, J. D.1 & Chapman, P. J.2 1Department of Biology, Middle Tennessee State University, Murfreesboro, TN 37132. 2US EPA (NHEERL), Gulf Ecology Division, 1 Sabine Island Dr., Gulf Breeze, FL 32561 Studies of the lipids of different algal species have revealed a diversity of fatty acids, sterols, and hydrocarbons, of which several are considered useful biomarkers, with potential for characterizing phytoplankton community composition. To extend this approach and characterize the lipids and lipid classes of laboratory-cultured marine dinoflagellates, a silicic acid fractionation system was developed to obtain compositional data for sterols and hydrocarbons of over forty species. In the course of this work, a neutral fraction obtained from a lipid extract of Pyrocystis lunula was found to contain an abundant quantity of a long-chain polyunsaturated hydrocarbon, along with previously reported keto-steranes. The hydrocarbon molecular weight (364) and retention time obtained by gas chromatography/mass spectrometry analysis suggested a C27 compound, which was confirmed by reduction (Adams catalyst) to give the straight chain alkane, n-heptacosane. The presence of eight double bonds was established by deuteration to give a product with molecular weight 396. While the positions of double bonds have not been established, the carbon number of this hydrocarbon and the number of double bonds strongly suggest formation by decarboxylation of the recently described, long-chain polyunsaturated C28 fatty acid shown to be a constituent of phospholipids. This hydrocarbon was not found in any other genus of the examined dinoflagellates, and appears to be one of the first identifications of a hydrocarbon in this class of algae. The function(s) of this compound in P. lunula is currently unclear. [source] Orthogonality of silver-ion and non-aqueous reversed-phase HPLC/MS in the analysis of complex natural mixtures of triacylglycerolsJOURNAL OF SEPARATION SCIENCE, JSS, Issue 21 2009Michal Hol Abstract The goal of this work is the study of possibilities of two basic separation modes used in the analysis of complex triacylglycerol (TG) samples of plant oils and animal fats, i.e. non-aqueous reversed-phase (NARP) and silver-ion HPLC coupled with atmospheric pressure chemical ionization mass spectrometry (APCI-MS). The orthogonality of both separation modes is tested for complex TG mixtures containing fatty acids (FAs) with different acyl chain lengths, different number, positions and geometry of double bonds (DBs) and different regioisomeric positions of FAs on the glycerol skeleton. The retention in NARP mode is governed by the equivalent carbon number, while the retention in silver-ion chromatography increases with the increasing number of DBs with a clear differentiation between cis - and trans- FAs. Moreover, silver-ion mode enables at least the partial resolution of regioisomeric TG mixtures including cis -/trans -regioisomers, as illustrated on two examples of randomization mixtures. Off-line 2D coupling of both complementary modes (NARP in the first dimension and silver-ion in the second dimension) yields the superior chromatographic selectivity resulting in the highest number of identified TGs ever reported for studied samples. Off-line 2D chromatograms are processed with the home-made software providing various ways of data visualization. [source] Resolution of triacylglycerol positional isomers by reversed-phase high-performance liquid chromatographyJOURNAL OF SEPARATION SCIENCE, JSS, Issue 12 2004Svetlana Momchilova Abstract The ability of reversed-phase high-performance liquid chromatography (RP-HPLC) to separate some positionally isomeric disaturated and monounsaturated triacylglycerols (TAGs) as intact species is demonstrated for the first time. Mobile phases of acetonitrile modified with methanol, ethanol, 2-propanol, 1-propanol, 1-butanol, acetone, or dichloromethane were tested for the separation of POP-PPO, PLP-PPL, PEP-PPE, and PDP-PPD (P , palmitic, O , oleic, L , linoleic, E , eicosapentaenoic, D , docosahexaenoic acid residue) on a single RP-HPLC column. The resolution improved with increasing number of double bonds in the acyl residues. While POP and PPO were only partially resolved, PDP and PPD were fully separated with all tested mobile phases, except those containing methanol. Also separated were the four TAGs having the same equivalent carbon number (ECN = 42), PEP, PPE, PDP, and PPD, on a single RP-HPLC column with mobile phase acetonitrile,2-propanol (70:30, v/v) at 0.8 mL/min. In all cases the isomer with the unsaturated acyl residue in either 1- or 3-position was retained more strongly than the respective 2-isomer. [source] HLD concept as a tool for the characterization of cosmetic hydrocarbon oils,POLYMER INTERNATIONAL, Issue 4 2003Véronique Nardello Abstract The HLD (hydrophilic lipophilic deviation) concept was applied to several water/i -C13En/2-propanol/hydrocarbon oil systems. For each oil, the optimum formulation, corresponding to HLD,=,0, was determined by systematically changing the formulation as a monotonic variation of the surfactant ethylene oxide number (EON) scanned variable. The optimum value for EON (symbolized as EON*) was accurately pinpointed both by estimating the solubilization and by measuring the interfacial tension with a spinning-drop tensiometer. This method allowed the classification of cosmetic hydrocarbon oils such as isohexadecane, paraffin oil, squalane, squalene and hydrogenated polydecenes in C30, C40, C40,C50, on an equivalent alkane carbon number (EACN) calibration scale based on five linear alkanes covering the liquid range (C5 to C16). © 2003 Society of Chemical Industry [source] Differential responses to branched and unsaturated aliphatic hydrocarbons in the rat olfactory systemTHE JOURNAL OF COMPARATIVE NEUROLOGY, Issue 4 2006Sabrina L. Ho Abstract In an effort to understand mammalian olfactory processing, we have been describing the responses to systematically different odorants in the glomerular layer of the main olfactory bulb of rats. Previously, we demonstrated chemotopically organized and distinct olfactory responses to a homologous series of straight-chained alkanes that consisted of purely hydrocarbon structures, indicating that hydrocarbon chains could serve as molecular features in the combinatorial coding of odorant information. To better understand the processing of hydrocarbon odorants, we now have examined responses to other types of chemical changes in these kinds of molecules, namely, branching and carbon,carbon bond saturation. To this end, we used the [14C]2-deoxyglucose method to determine glomerular responses to a group of eight-carbon branched alkane isomers, unsaturated octenes (double-bonded), and octynes (triple-bonded). In contrast to the differential responses we observed previously for straight-chained alkanes of differing carbon number, the rat olfactory system was not particularly sensitive to these variations in branching and bond saturation. This result was unexpected, given the distinct molecular conformations and property profiles of the odorants. The similarity in activity patterns was paralleled by a similarity in spontaneous perceptual responses measured using a habituation assay. These results demonstrate again the functional relationship between bulbar activity patterns and odor perception. The results further suggest that the olfactory system does not respond equally to all aspects of odorant chemistry, functioning as a specific, rather than a general, chemical analysis system. J. Comp. Neurol. 499:519,532, 2006. © 2006 Wiley-Liss, Inc. [source] Use of TLC-FID and GC-MS/FID to examine the effects of migratory state, diet and captivity on preen wax composition in White-throated Sparrows Zonotrichia albicollisIBIS, Issue 4 2010RAYMOND H. THOMAS Preen wax is important for plumage maintenance and other functions. Its chemical composition is complex, and separating and quantifying its components, commonly by gas chromatography (GC), can be challenging. We present a simple analytical system consisting of thin-layer chromatography/flame ionization detection (TLC-FID) using a solvent system of 100% toluene to analyse the complex compound classes present in preen wax. We used GC and TLC-FID to investigate the effects of migratory status, diet and captivity on the preen wax composition of White-throated Sparrows Zonotrichia albicollis, and to measure the quantity of preen wax on the head, primary and tail feathers. White-throated Sparrows produced preen wax containing only monoesters regardless of migratory state. The monoesters contained several isomers consisting of homologous series of fatty alcohols (C10,C20) and fatty acids (C13,C19) esterified together in different combinations to form monoesters with total carbon numbers ranging from C23 to C38. Weighted average monoester carbon number was greater in captive birds than in wild birds and was greater in captives fed a formulated diet enriched with sesame oil than in birds fed the same diet enriched with fish oil. Captivity and migratory state also affected the complexity of the mixture of monoesters. There was significantly more preen wax on head feathers compared with primary and tail feathers. We suggest that among its many functions, preen wax may play a role in drag reduction by affecting the physical properties of feathers, and/or the fluid flow at their surfaces. [source] The Combined Catalytic Action of Solid Acids with Nickel for the Transformation of Polypropylene into Carbon Nanotubes by PyrolysisCHEMISTRY - A EUROPEAN JOURNAL, Issue 11 2007Rongjun Song Abstract The effects of both organically modified montmorillonite (OMMT) and Ni2O3 on the carbonization of polypropylene (PP) during pyrolysis were investigated. The results from TEM and Raman spectroscopy showed that the carbonized products of PP were mainly multiwalled carbon nanotubes (MWNTs). Surprisingly, a combination of OMMT and Ni2O3 led to high-yield formation of MWNTs. X-ray powder diffraction (XRD) and GC,MS were used to investigate the mechanism of this combination for the high-yield formation of MWNTs from PP. Brønsted acid sites were created in degraded OMMT layers by thermal decomposition of the modifiers. The resultant carbenium ions play an important role in the carbonization of PP and the formation of MWNTs. The degradation of PP was induced by the presence of carbenium ions to form predominantly products with lower carbon numbers that could be easily catalyzed by the nickel catalyst for the growth of MWNTs. Furthermore, carbenium ions are active intermediates that promote the growth of MWNTs from the degradation products with higher carbon numbers through hydride-transfer reactions. The XRD measurements showed that Ni2O3 was reduced into metallic nickel (Ni) in situ to afford the active sites for the growth of MWNTs. [source] | ||||||||||||||||