Chain Aliphatic Hydrocarbons Research Articles

Hydrotreating of fast pyrolysis oils from protein-rich pennycress seed presscake

The fast pyrolysis oils produced from proteinaceous biomass, such as pennycress presscake differ significantly from those produced from biomass with mostly lignocellulosic composition. Those from proteinaceous biomass tend to be deoxygenated, contain more nitrogen, be less acidic and be more stable. Because their composition is different, their behavior in and products from upgrading via hydrotreating will be different. We studied the mild batch hydrogenation of the pyrolysis oil produced from pennycress presscake at ∼13.8MPa (138bar) H2 and 320°C over five precious metal on charcoal catalysts: two Ru/C catalysts, two Pd/C catalysts, and one Pt/C catalyst. The liquid products were characterized by elemental analysis, GC×GC/MS and NMR. The Ru catalysts were most effective at further deoxygenating the pyrolysis oils, with the Pd catalyst slightly less effective, and the Pt catalyst the least effective. None of the catalysts were highly effective for hydrodenitrogenation, though among them Pt removed the most nitrogen from the liquids. Using the best catalysts, an upgraded pyrolysis oil containing <15wt% total heteroatom content (O+N+S) with an HHV of 37.0MJ/mg was realized. Compared with wood pyrolysis oils upgraded at similar conditions, the upgraded pyrolysis oils from pennycress presscake had lower oxygen and total heteroatom (O, N, and S) content, had higher energy content and were closer compositionally to petroleum. The products were very rich in long aliphatic hydrocarbon chains; these large aliphatic moieties were present in both purely hydrocarbon compounds and in heteroatom containing compounds especially alkyl amides.

The Influence of Process Conditions on the Chemical Composition of Pine Wood Catalytic Pyrolysis Oils

Pine wood samples were used as model feedstock to study the properties of catalytic fast pyrolysis oils. The influence of two commercial zeolite catalysts (BASF and SudChem) and pretreatment of the pine wood with sodium hydroxide on pyrolysis products were investigated. The pyrolysis oils were first fractionated using column chromatography and characterized using GC-MS. Long chain aliphatic hydrocarbons, levoglucosan, aldehydes and ketones, guaiacols/syringols, and benzenediols were the major compounds identified in the pyrolysis oils. The catalytic pyrolysis increased the polycyclic hydrocarbons fraction. Significant decreases in phthalate derivatives using SudChem and long chain aliphatics using BASF catalyst were observed. Significant amounts of aromatic heterocyclic hydrocarbons and benzene derivatives were formed, respectively, using BASF and SudChem catalysts. Guaiacyl/syringyl and benzenediols derivatives were partly suppressed by the zeolite catalysts, while the sodium hydroxide treatment enriched phenolic derivatives. Zeolite catalyst and sodium hydroxide were employed together; they showed different results for each catalyst.

Modulation of Antimicrobial Host Defense Peptide Gene Expression by Free Fatty Acids

Routine use of antibiotics at subtherapeutic levels in animal feed drives the emergence of antimicrobial resistance. Development of antibiotic-alternative approaches to disease control and prevention for food animals is imperatively needed. Previously, we showed that butyrate, a major species of short-chain fatty acids (SCFAs) fermented from undigested fiber by intestinal microflora, is a potent inducer of endogenous antimicrobial host defense peptide (HDP) genes in the chicken (PLoS One 2011, 6: e27225). In the present study, we further revealed that, in chicken HD11 macrophages and primary monocytes, induction of HDPs is largely in an inverse correlation with the aliphatic hydrocarbon chain length of free fatty acids, with SCFAs being the most potent, medium-chain fatty acids moderate and long-chain fatty acids marginal. Additionally, three SCFAs, namely acetate, propionate, and butyrate, exerted a strong synergy in augmenting HDP gene expression in chicken cells. Consistently, supplementation of chickens with a combination of three SCFAs in water resulted in a further reduction of Salmonella enteritidis in the cecum as compared to feeding of individual SCFAs. More importantly, free fatty acids enhanced HDP gene expression without triggering proinflammatory interleukin-1β production. Taken together, oral supplementation of SCFAs is capable of boosting host immunity and disease resistance, with potential for infectious disease control and prevention in animal agriculture without relying on antibiotics.

Biodegradation of methyl tert-butyl ether by cometabolism with hexane in biofilters inoculated with Pseudomonas aeruginosa

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−1. Intermediate tert-butyl alcohol (TBA) accumulation was observed followed by its gradual consumption. A maximum MTBE elimination capacity (ECMAX) of 35 g m−3 h−1 and removal efficiency (RE) of 70% were attained in mineral medium amended biofilters having an empty bed residence time (EBRT) of 1 min. For these experimental conditions, a maximum hexane EC of approximately 60 g m−3 h−1 was obtained at a load of 75 g m−3 h−1. Experiments under transient conditions revealed a competitive substrate interaction between MTBE and hexane. Biomass densities between 5.8 and 12.6 g Lbiofilter −1 were obtained. Nevertheless, production of biopolymers caused non-uniform distribution flow rates that reduced the performance. Residence time distribution profiles showed an intermediate dispersion flow rate with a dispersion coefficient of 0.8 cm2 s−1.

Characterization of Physic nut (Jatropha curcas L.) shells

The characterization of Physic nut shells was done using the wet chemical analysis of wood components. The obtained fractions were analyzed using IR, NMR, GPC, ICP and MALDI-TOF mass spectroscopy. TGA was used to determine the fixed carbon (+ash) and water content of the shells. The results of wet chemical analysis of wood components offered a clear procedure to isolate the main components in Physic nut shells ((a) under bar). The fractions obtained were: polar extract ((b) under bar), non-polar extract ((c) under bar), Acid Insoluble Lignin ((d) under bar), Holocellulose ((e) under bar), alpha-Cellulose T. The total Lignin content present in the shells equaled 48.84%. IR and NMR spectroscopy demonstrated that the non-polar extract is Lignin, which corresponds to the extractable Lignin (1.24%) in the Physic nut shells and the Acid Insoluble Lignin was 47.60%. Elemental analysis showed no Sulfur present in the investigated materials. Furthermore both H-1 and C-13 NMR of the non-polar extract showed the presence of aliphatic hydrocarbon chains. The a-Cellulose content (22.29%) and the Hemicelluloses content (23.84%) were in line with that of agricultural residues. The water content and the fixed carbon content (+ash [2.8%]) equal 5-6% and 35.6%, respectively. GPC showed that the polydispersity of the non-polar extract (3.6) lies between Alcell Lignin and Kraft Lignin. The polar extract contains a variety of metals, with especially a high amount of the alkali metals K and Na. The extraction with water is proposed to generate a fertilizer fraction and may be applied to reduce potential sintering issues during eventual combustion or gasification of the shells. (C) 2011 Elsevier Ltd. All rights reserved.

Aggregation induced emission switching and electrical properties of chain length dependent π-gels derived from phenylenedivinylene bis-pyridinium salts in alcohol–water mixtures

Supramolecular π-gels were formed in a mixture of aliphatic alcohols and water for a series of chromophoric phenylenedivinylene bis-N-alkyl pyridinium salts (PPV) appended with terminal aliphatic hydrocarbon chains of different lengths. Gelation could be controlled either by altering the ratio of various alcohol–water mixtures or by changing the aliphatic chain length of the gelator. The temperature- and the ratio-variation in the ethanol–water mixtures exhibited a tunable emission behavior depending on the extent of aggregation which was promoted by aromatic π-stacking, van der Waals and electrostatic interactions among the individual PPV units. Thus, a light-blue emission at higher temperature (>40 °C), a reddish-orange emission at low temperature (<20 °C) and a white-light emission at room temperature (25–30 °C) were observed in solution. The gelators possessing longer aliphatic chains exhibited a higher gel-melting temperature, increased viscoelasticity and shorter fiber diameter based on a delicate hydrophobic/hydrophilic balance. A semiconducting nature of the electrical conductivity was observed for the individual compounds and the magnitude of the current increased with increasing width of the gel fibers upon decreasing the aliphatic chain length. A reversible one-electron redox behavior was observed for the chromophore and the redox potential decreased with the increase in the chain length. A diffusion-controlled redox behavior was observed for the gelators with shorter aliphatic chains. However, the compounds with longer chains made the process diffusion-limited.

Evaluation of on-line pyrolysis two-dimensional gas chromatography time-of-flight mass spectrometry (Py–GC × GC–ToFMS) on whole sediments from a Mediterranean sapropel sequence

Analysis of the molecular composition of the organic matter (OM) from whole sediment samples can avoid analytical bias that might result from isolation of components from the sediment matrix, but has its own analytical challenges. We evaluated the use of GC × GC–ToFMS to analyze the pyrolysis products of six whole sediment samples obtained from above, within and below a 1 million year old OM-rich Mediterranean sapropel layer. We found differences in pyrolysis products < n-C 22 between the OM-rich sapropel samples and the OM-poor background marls. The presence of alkyl pyrroles, probably derived from chlorophyll, in pyrolysates of the sapropels but not in those of the marls suggests that higher marine productivity and greater OM preservation accompanied deposition of the sapropels. Detection of tetramethyl benzenes considered to be pyrolysis products of isorenieratene in the sapropel samples is evidence that nitrogen-fixing green sulfur bacteria contributed to the high productivity. Greater abundances of shorter chain aliphatic hydrocarbons, pyrroles, furans and alkyl aromatics in the pyrolysates of sapropel samples relative to the marls confirm better preservation of marine OM in the sapropels. In addition, the presence of greater amounts of thiophenes in the sapropels than in the marls is consistent with the existence of euxinic conditions during sapropel deposition. The combination of whole sediment pyrolysis and GC × GC–ToFMS is promising, but the procedure requires careful selection of its multiple analytical variables, particularly the pyrolysis temperature and the operational features of the GC columns.

Late Quaternary environmental change of Yellow River Basin: An organic geochemical record in Bohai Sea (North China)

Bulk geochemical characterization (total organic carbon, grain size distribution, carbon isotope composition) and molecular biomarkers (lignin phenols, straight chain aliphatic hydrocarbons, glycerol dialkyl glycerol tetraethers) were analyzed for a 21 m core from the Bohai Sea (North China), spanning ca 21 ka BP. These paleo-proxies presented remarkable differences between the late glacial period and the Holocene, reflecting continental and coastal environments, respectively. Two peat layers were deposited during the period of ca 9000–8460 yr BP. Thereafter the core site has been consistently covered by seawater until recent reclamation of land from the sea. The occurrence of a total organic carbon maximum from ca 6000–3800 yr BP was attributed to delivery of organic carbon enriched sediments via the Yellow River, consistent with increased vegetation density and higher development of soil under warm and humid mid-Holocene climate conditions. The distributions of lignin phenol compositions and C 31/C 29 n-alkane ratio suggested the largest expansion of woody plants between ca 5300 and 4000 yr BP, corresponding to the extremely favorable climatic conditions. Since ca 3800 yr BP, an abrupt increase in the C 31/C 29 n-alkane ratio suggested higher abundance of grasses, consistent with a drying climate trend after the mid-Holocene. Since our coastal sediments close to the Yellow River outflow contain catchment-integrated environmental signals of the river basin, molecular proxies demonstrate that the variability of vegetation distributions in the Holocene is a widespread phenomenon in those areas adjacent to Yellow River Basin.

Retrieval and tentative indentification of the 3 μm spectral feature in Titan's haze

Recently, an unidentified 3.3–3.4μm feature found in the solar occultation spectra of the atmosphere of Titan observed by Cassini/VIMS was tentatively attributed to the C–H stretching mode of aliphatic hydrocarbon chains attached to large organic molecules, but without properly extracting the feature from adjacent influences of strong CH4 and weak C2H6 absorptions (Bellucci et al., 2009). In this work, we retrieve the detailed spectral feature using a radiative transfer program including absorption and fluorescent emission of both molecules, as well as absorption and scattering by haze particles. The spectral features of the haze retrieved from the VIMS data at various altitudes are similar to each other, indicating relatively uniform spectral properties of the haze with altitude. However, slight deviations observed near 127km and above 300km suggest inhomogeneity at these altitudes. We find that the positions of the major spectral peaks occur at 3.33–3.37μm, which are somewhat different from the typical 3.3μm aromatic or 3.4μm aliphatic C–H stretches usually seen in the spectra of dust particles of the interstellar medium and comets. The peaks, however, coincide with those of the solid state spectra of C2H6, CH4, and CH3CN; and a broad shoulder from 3.37 to 3.50μm coincides with those of C5H12 and C6H12 as well as those of typical aliphatic C–H stretches. This result combined with high-altitude (∼1000km) haze formation process recently reported by Waite et al. (2007) opens a new question on the chemical composition of the haze particles. We discuss the possibility that the 3μm feature may be due to the solid state absorption bands of these molecules (or some other molecules) and we advocate additional laboratory measurements for the ices of hydrocarbon and nitrogen-bearing molecules present in Titan's atmosphere for the identification of this 3μm feature.

Water Quality Issues in the Niger Delta of Nigeria: Polyaromatic and Straight Chain Hydrocarbons in Some Selected Surface Waters

Surface water samples were collected from mid-Niger Delta, Nigeria, Bayelsa, Delta and Rivers States with high petroleum activities. The impact of these activities on potable water was investigated by determination of polyaromatic and straight chain hydrocarbon contents. The 16 US EPA priority polynuclear aromatic hydrocarbons PAHs, straight chain hydrocarbon (C8–C40), pH, temperature, chloride (Cl−), were determined. Pseudomonas sp, Proteus sp, Bacillus sp, Penicillium sp, Achromobacter sp and Aspergillus sp were also determined. All the parameters were determined using their respective standard methods. Anieze river in Port-Harcourt had six (6) PAHs-Acenaphthene (0.015 mg/l), 1,2-Benzanthracene (0.004 mg/l), Benzo(b) fluoranthene (0.064 mg/l), Benzo(g, h, i) perylene (0.009 mg/l), Dibenzo(a, h) anthracene (0.040 mg/l) and chrysene (0.015 mg/l). Orash river had chrysene (0.017 mg/l) and fluorene (0.109 mg/l). Only Ifie-Kporo river in Delta State had Dibenzo(a, h) anthracene (4.350 mg/l), while none of the water samples from Bayelsa had any of 16 PAHs. Straight chain aliphatic hydrocarbon of the order C8–C14 were not detected in majority of the samples, whereas C15–C40 were detected in most of the samples with highest to lowest concentrations in water samples from Rivers, Delta and Bayelsa States, respectively. Temperatures above 30°C were seen in some water bodies and highest chloride level was seen in Ozubo river (Rivers state) 17,198.00±0.06 mg/l and 15,850.00±0.03 mg/l in dry and rainy seasons respectively. The pH of all the samples are within internationally accepted limits, except Egbo stream (pH 5.53), Olomoro burrow pit stream (pH 5.79) and Ughewhe stream (pH 5.32), all in Delta State; while Orash river (pH 5.22). In view of the negative impact of surface water in the Niger Delta by petroleum activities and its possible public health importance, we recommend water quality monitoring and suggest the possibility of developing a biomarker for determining the age of a particular pollution.

Synthesis of 3-hydroxyflavone fluorescent probes and study of their fluorescence properties

Direct measurement of dipole potential in biological membranes has been impossible and 3-hydroxyflavones (3HFs) have allowed detection of changes in dipole potential in biological systems. In the present study, sixteen derivatives of 3HF with aliphatic hydrocarbon chains of different lengths at 4′-position and 6-position were synthesized. The basic fluorescence properties of 3HFs are maintained in all the probes in terms of strong blue shift in maximum fluorescence emission wavelength and >100 fold increase in quantum yield in organic solvents and in dioleoylphosphatidylcholine (DOPC) small unilamellar vesicles (SUV) in comparison to in aqueous Hepes buffer (15 mmol/L, pH 7.4). More importantly, the ability of the new compounds to report dipole potential changes in biological systems are also maintained, since all the new probes showed spectrum properties that are similar to yet different from that of F4N1, which potentially may allow more sensitive measurement of the dipole potential change in membranes.

Structural Characterization of a Soluble Amyloid β-Peptide Oligomer

Alzheimer's disease (AD) is a neurodegenerative disorder that is linked to the presence of amyloid beta-peptides that can form insoluble fibrils or soluble oligomeric assemblies. Soluble forms are present in the brains and tissues of Alzheimer's patients, and their presence correlates with disease progression. Long-lived soluble forms can be generated in vitro by using small amounts of aliphatic hydrocarbon chains of detergents or fatty acids in preparations of amyloid beta-peptides. Using NMR, we have characterized soluble oligomers of Abeta preglobulomer and globulomer that are stable and alter synaptic activity. The NMR data indicate that these soluble forms have a mixed parallel and antiparallel beta-sheet structure that is different from fibrils which contain only parallel beta-sheets. Using the structural data, we engineered a disulfide bond into the soluble Abeta globulomer to give a "new" soluble antigen that is stable, homogeneous, and binds with the same affinity to selective antibodies as the parent wt globulomer.

Reaction Types and Kinetics of Methane Generation from Huolinhe Lignite Pyrolysis by TG/MS Experiment and Quantum Chemical Calculations

Open system pyrolysis modeling of immature Huolinhe lignite(vitrinite reflectivity,RmO0ax0 of 0.33%) was carried out and an on-line curve for the methane generation rate was obtained using a thermogravimetric analyzer coupled to a quadrupole mass spectrometer(TG/MS) . Five peaks were suitable for curve fitting. A kinetic analysis of these fitted curves indicated that the lowest temperature peak represented desorption of adsorbed methane in coal and the four other peaks were from pyrolytic methane generation. These results indicated four types of reactions as determined by kinetic analysis combined with the structural characterization of coal by 13C-NMR and quantum chemical calculations. From the order of peak fitting,the first type of reaction involves a cleavage of the aliphatic carbons linked to O atoms;the second includes two reactions,a β-secession of short chain aliphatic functional groups and a secondary cracking of long chain aliphatic hydrocarbons that were formed during the primary pyrolysis of coal;the third is a demethylation of methyl-linked aromatic clusters;and the fourth is an aromatization of aliphatic substances within the coal structure and subsequent condensation.

Titan solar occultation observed by Cassini/VIMS: Gas absorption and constraints on aerosol composition

A solar occultation by Titan's atmosphere has been observed through the solar port of the Cassini/VIMS instrument on January 15th, 2006. Transmission spectra acquired during solar egress probe the atmosphere in the altitude range 70 to 900 km at the latitude of 71° S. Several molecular absorption bands of CH 4 and CO are visible in these data. A line-by-line radiative transfer calculation in spherical geometry is used to model three methane bands (1.7, 2.3, 3.3 μm) and the CO 4.7 μm band. Above 200 km, the methane 2.3 μm band is well fit with constant mixing ratio between 1.4 and 1.7%, in agreement with in situ and other Cassini measurements. Under 200 km, there are discrepancies between models and observations that are yet fully understood. Under 480 km, the 3.3 μm CH 4 band is mixed with a large and deep additional absorption. It corresponds to the C–H stretching mode of aliphatic hydrocarbon chains attached to large organic molecules. The CO 4.7 μm band is observed in the lower stratosphere (altitudes below 150 km) and is well fit with a model with constant mixing ratio of 33 ± 10 ppm . The continuum level of the observed transmission spectra provides new constraints on the aerosol content of the atmosphere. A model using fractal aggregates and optical properties of tholins produced by Khare et al. [Khare, B.N., Sagan, C., Arakawa, E.T., Suits, F., Callcott, T.A., Williams, M.W., 1984. Icarus 60, 127–137] is developed. Fractal aggregates with more than 1000 spheres of radius 0.05 μm are needed to fit the data. Clear differences in the chemical composition are revealed between tholins and actual haze particles. Extinction and density profiles are also retrieved using an inversion of the continuum values. An exponential increase of the haze number density is observed under 420 km with a typical scale height of 60 km.

Peroxidases in YR-1 strain ofMucor circinelloides a potential bioremediator of petroleum-contaminated soils

We have studied the induction and subcellular localisation of peroxidase activity present in cell-free extracts of YR-1 strain ofMucor circinelloides in relation with different growth conditions, particularly different carbon sources; the results obtained indicated that the peroxidase expression could be an inducible mechanism depending on the carbon source used. Peroxidase was induced in the presence of hydrocarbons or methanol meanwhile in glucose no activity was founded. On zymograms of peroxidase activity after polyacrylamide gel-electrophoresis two different activity bands were revealed, one of them (major band) shows different relative mobility depending on the aliphatic hydrocarbon chain length used as carbon source, indicating the possibility that could exist different iso-forms of the peroxidase activity. In an immunological approach using a polyclonal antibody against commercial peroxidase, the result shows that the antibody recognised the same two bands revealed in zymogram indicating that activity bands possesses a similar epitope in their structure. On SDS-PAGE loading supernatants obtained by high-speed centrifugation from cell-free extracts of YR-1 grown in glucose,n-decane or methanol, were detected different prominent protein bands at (in kDa): 64 and 94 (glucose), 27 and 46 (n-decane), and 28 and 47 (n-hexadecane) in comparison with a 55 kD band of horseradish peroxidase used as a control. These protein-bands could be the putative subunits of each iso-form in the native protein. Preliminary studies about the intracellular localisation of the enzyme using isopicnic-sucrose gradients suggest that it is located in the peroxisomal fraction.

Molecular evidence for life in the 3.5 billion year old Warrawoona chert

The biological origin of organic matter in the oldest siliceous sediments (cherts) is still debated. To address this issue, the insoluble organic matter (kerogen) was isolated from a chert of the Warrawoona group. The chemical structure of the kerogen was investigated through a combination of analytical techniques including solid-state 13C nuclear magnetic resonance and pyrolysis. Although dominated by aromatic hydrocarbons, the pyrolysate comprises a homologous series of long chain aliphatic hydrocarbons characterized by odd-over-even carbon number predominance. This distribution is only consistent with a biological origin. As kerogen must be contemporaneous of the solidification of the chert, this observation should be regarded as an evidence for the presence of life on Earth, 3.5 By ago.

Mesoporous polyaniline having high conductivity at room temperature

We report a new method to synthesize nanostructured polyaniline by using the self-assembly of a mixture of an anionic surfactant sodium dodecylsulfate (SDS) and a non-ionic surfactant, Brij 35 (C 12H 25-(OC 2H 4) 23-OH, a polyether and aliphatic hydrocarbon chain surfactant) as structure directing agents (SDA). The in situ polymerization of aniline was carried out at 277–278 K in the presence of these SDAs with ammonium persulfate as the oxidant. Mesophase formation of the product polymer composites was studied with or without the addition of a co-surfactant molecule or by changing other synthesis parameters. Powder X-ray diffraction and transmission electron microscopic studies suggested wormhole-like disordered structure. N 2 adsorption studies suggested the existence of mesopores with pore widths varying from small to large mesopores in these nanostructured materials, after the removal of the SDAs. The chemical bonding and electronic structure of the mesoporous polyaniline samples were also studied by FT-IR and UV–visible spectroscopic studies. These mesoporous polyaniline samples showed excellent luminescence and conducting properties at room temperature. These π-conjugated polymeric nanomaterials have huge potential in the fabrication of sensors, microelectronic, photo-devices and organic LEDs.

Characterization of lipophilic wood extractives from clones of Eucalyptus urograndis cultivate in Brazil

The chemical compositions of the lipophilic extractives from four clones of Eucalyptus urograndis cultivated in Brazil were studied by gas chromatography-mass spectrometry (GC-MS) before and after alkaline hydrolysis. The four E. urograndis clones showed similar amounts of dichloromethane soluble (lipophilic) extractives (0.38-0.55% w/w). The major groups of compounds identified in the lipophilic fraction of extractives consisted mainly of fatty acids (mainly palmitic linoleic and oleic acids and small amounts of a- and w-hydroxyacids), steroids (mainly b-sitosterol, b-sitostanol), followed by minor amounts long chain aliphatic alcohols, hydrocarbons and aromatic compounds. The relative abundances of these groups were similar for three of the clones with exception of the clone Ugc, which was shown to have much higher amounts of fatty acids and sterols. The high amounts of extractives found in these clones, and particularly of Ugc, when compared with other Eucalyptus species, suggests an increased risk of pitch formation during bleached pulp production.

Titanium-rich highly ordered mesoporous silica synthesized by using a mixed surfactant system

A new titanium-rich highly ordered 2-D hexagonal mesoporous titanium silicate has been synthesized using a mixture of cationic (cetyltrimethylammonium bromide, CTAB) and non-ionic (Brij-35, C 12H 25-(OC 2H 4) 23-OH, a polyether and aliphatic hydrocarbon chain surfactant) mixed surfactant system as the supramolecular structure directing agent (SDA) in the presence of tartaric acid (TA) as a mineralizer of Ti(IV). XRD, N 2 adsorption and TEM data suggested the presence of mesophase with hexagonal pore arrangements and the UV–visible, FT IR and XPS studies suggested the incorporation of mostly tetrahedral titanium (IV) species in the highly ordered silica network. This mesoporous titanium silicate material showed excellent catalytic activity and selectivity in the epoxidation of styrene using dilute aqueous H 2O 2 as oxidant.

Chemistry and geographic variation of floral scent in Yucca filamentosa (Agavaceae)

We identified volatiles from the floral headspace of Yucca filamentosa using gas chromatography and mass spectrometry and analyzed floral scent composition and variation among populations pollinated by different yucca moth species. Twenty-one scent compounds were repeatedly identified and most could be categorized into two major classes: (1) homoterpenes derived from the sesquiterpene alcohol nerolidol and (2) long chain aliphatic hydrocarbons. Two biosynthetic pathways are thus responsible for the majority of floral volatiles in Y. filamentosa. The homoterpene E-4,8-dimethylnona-1,3,7-triene, which is released systemically by higher plants upon herbivory, was the most abundant compound. Two di-oxygenated compounds not previously reported as floral compounds also were detected. No differentiation in floral scent was observed between populations pollinated by different yucca moths, nor was there any correlation between chemical distance and geographic distance among populations. The total release rate of volatiles differed significantly among populations, but not between populations with different pollinators. The combination of unique compounds and low variation in the fragrance blend may reflect highly selective attraction of obligate pollinators to flowers. The observed lack of differentiation in floral scent can putatively explain high moth-mediated gene flow among sites, but it does not explain conservation of odor composition across populations with different pollinators.