Abstract  A library of chiral hemisalen ligands (30) was realized. The ligands were synthesized by the condensation of salicylaldehyde derivatives with amino-alcohols (amino-indanol or substituted amino-ethanol) and characterized. These ligands associated with ruthenium (II) precursors were tested on the asymmetric transfer hydrogenation (ATH) of aromatic ketones by sodium formate in water. The different substituent pattern on the ligand (electronic and hindrance effects on different positions) as well as the ruthenium precursor were investigated. The best compromise in terms of conversion and chiral induction led to the complex [RuCl2(mesitylene)](2) coordinated to (1S,2R)-1-((E)-(3(dimethyl(phenyl)silyl)-2-hydroxy-5-methoxy benzylidene) amino)-2,3-dihydro-1H-inden-2-ol (L25). It reduces acetophenone in 95% yield and 91% ee in 18 h at 30 degrees C. (C) 2013 Academie des sciences. Published by Elsevier Masson SAS. All rights reserved.

Abstract  Anaerobic/anoxic biodegradation of hydrocarbons offers an attractive approach to the removal of these compounds from polluted environments such as aquifers, aquatic sediments, submerged soils and subsurface soils. The application of nitrate was investigated to accelerate the degradation of gasoline components such as mono-aromatic hydrocarbons and total petroleum hydrocarbons (TPH) in soil by indigenous microorganisms under anoxic condition. The addition of nitrate had little effect on the degradation of mono-aromatic hydrocarbons m- & p-xylene, o-xylene, sec-butylbenzene and 1,2,4-trimethylbenzene, but facilitated the degradation of TPH (C6-C12) and mono-aromatic hydrocarbons toluene and ethylbenzene markedly. Furthermore, the more nitrate added, the higher the percentage of toluene, ethylbenzene and TPH (C6-C12) degraded after 180 days of anoxic incubation. Microorganisms capable of degrading toluene, ethylbenzene and TPH (C6-C12) with nitrate as the electron acceptor under anaerobic/anoxic condition are composed predominantly of Alpha-, Beta-, Gamma- or Delta-proteobacteria. Beta- and Gamma-proteobacteria were the main components of indigenous microorganisms, and accounted for 83-100% of the total amount of indigenous microorganisms in soil used in this study. Furthermore, the total amount of indigenous microorganisms increased with nitrate added. The addition of nitrate stimulated the growth of indigenous microorganisms, and therefore facilitated the degradation of toluene, ethylbenzene and TPH (C6-C12).

Abstract  Cooligomerization of liquid products of the C9 fraction of diesel fuel pyrolysis to produce cooligomers of wide application is suggested to be carried out with silica-alumina catalysts, among which the activated bentonite clay seems to be optimal. Cooligomerization of the mixture simulating the C-9 fraction composition was studied to compare the suggested heterogeneous catalytic method with other methods of cooligomers production. Different methods have been compared in terms of yield of cooligomers and their properties, namely molecular weight and its distribution, density, unsaturation and colour. The ratio of monomer units in cooligomer has been determined and the monomers conversion degrees have been calculated for different cooligomerization methods. Reasons of structure and composition differences of cooligomers obtained by different methods are suggested.

Abstract  Pincer (Phebox)Ir(mesityl)(OAc) (2) (Phebox = 3,5-dimethylphenyl-2,6-bis(oxazolinyl)) complex, formed by benzylic C-H activation of mesitylene (1,3,5-trimethylbenzene) using (Phebox)Ir(OAc)2OH2 (1), was treated with thionyl chloride to rapidly form 1-(chloromethyl)-3,5-dimethylbenzene in 50% yield at 23 °C. A green species was obtained at the end of reaction, which decomposed during flash column chromatography to form (Phebox)IrCl2OH2 in 87% yield.

Abstract  The dimers of pentamethyliridocene and ruthenium pentamethylcyclopentadienyl mesitylene, (IrCp*Cp)2 and (RuCp*mes)2, respectively, are shown here to be effective solution-processable reagents for lowering the work functions of electrode materials; this approach is compared to the use of solution-deposited films of ethoxylated poly(ethylenimine) (PEIE). The work functions of indium tin oxide (ITO), zinc oxide, and gold electrodes can be reduced to 3.3-3.4 eV by immersion in a toluene solution of (IrCp*Cp)2; these values are similar to those that can be obtained by spin-coating a thin layer of PEIE onto the electrodes. The work-function reductions achieved using (IrCp*Cp)2 are primarily attributable to the interface dipoles associated with the formation of submonolayers of IrCp*Cp(+) cations on negatively charged substrates, which in turn result from redox reactions between the dimer and the electrode. The electrical properties of C60 diodes with dimer-modified ITO cathodes are similar to those of analogous devices with PEIE-modified ITO cathodes.

Abstract  Steryl ferulates synthesised from commercial sterols as well as commercial oryzanol were used to better understand how structural features affect antioxidant activity in vitro by the ABTS(+) radical decolorization assay, by oxidative stability index (OSI) of soybean oil, and by analysis of antioxidant activity during frying. Steryl ferulates inhibited the ABTS(+) radical by 6.5-56.6%, depending on their concentration, but were less effective, especially at lower concentrations, than ferulic acid. Ferulic acid and steryl ferulates had either no effect, or lowered the OSI of soybean oil by up to 25%, depending on the concentration. In their evaluation as frying oil antioxidants, steryl ferulates with a saturated sterol group had the best antioxidant activity, followed by sterols with one double bond in the C5 position. The results indicate that a dimethyl group at C4 as well as a C9,C19 cyclopropane group, as found in oryzanol, negatively affects antioxidant activity in frying oils.

Abstract  The quest for renewable and cleaner energy sources to meet the rapid population and economic growth is more urgent than ever before. Being the most abundant carbon source in the atmosphere of Earth, CO2 can be used as an inexpensive C1 building block in the synthesis of aromatic fuels for internal combustion engines. We designed a process capable of synthesizing benzene, toluene, xylenes and mesitylene from CO2 and H2 at modest temperatures (T = 380 to 540 °C) employing Fe/Fe3O4 nanoparticles as catalyst. The synthesis of the catalyst and the mechanism of CO2-hydrogenation will be discussed, as well as further applications of Fe/Fe3O4 nanoparticles in catalysis.

Abstract  CelTherm is a biochemical process to produce renewable fuels and chemicals from lignocellulosic biomass. The present study's objective was to determine the level of treatment/purity of the microbial triacylglyceride oil (TAG) necessary to facilitate fuel production. After a unique microbe aerobically synthesizes TAG from biomass-derived sugars, the microbes were harvested and dried then crude TAG was chemically extracted from the residual biomass. Some TAGs were further purified to hydrotreating process requirements. Both grades were then noncatalytically cracked into a petroleum-like intermediate characterized by gas chromatography. Experiments were repeated using refined soybean oil for comparison to previous studies. The products from crude microbial TAG cracking were then further refined into a jet fuel product. Fuel tests indicate that this jet fuel corresponds to specifications for JP-8 military turbine fuel. It was thus concluded that the crude microbial TAG is a suitable feedstock with no further purification required, demonstrating CelTherm's commercial potential.

Abstract  Our previous study reported that a mixture of cerebrosides from traditional Chinese medicine Baifuzi could activate BKCa channel. It is curious to know the effect of each single cerebroside on the channel. Here we isolated 5 pure cerebrosides from the mixture and determined their chemical structures. The most potent one increased the single channel open probability 6 folds with EC50 value of 1.0 μM. The structure-activity relationship revealed that acyl chain length of cerebrosides has potent effect, while configuration of double bond at C8-C9 on their long chain base has weak effect on the channel activity. Thus, this research provides a guide for design and synthesis of a lead cerebroside with more potent effect on the BKCa channel.

Abstract  A 3D metal-organic framework, [NH2(CH3)(2)](2)[Cd-17(L)(12)(mu(3)-H2O)(4)(DMF)(2)(H2O)(2)]center dot solvent (1), has been constructed with a pi-electron rich aromatic ligand 2,4,6-tris[1-(3-carboxylphenoxy) ylmethyl] mesitylene (H3L) and d(10) configuration metal ion Cd2+ under solvothermal conditions. The crystal structure reveals that complex 1 consists of hexanuclear and trinuclear cadmium building units, which are further bridged by the multicarboxylate ligands to give a (3, 6, 12)-connected topological net. This complex exhibits strong ligand originated photoluminescence emission, which is selectively sensitive to electron-deficient nitroaromatic explosives (nitrobenzene, 4-nitrotoluene, 1,4-dinitrobenzene, 1,3-dinitrobenzene and 2,4-dinitrotoluene). This property makes complex 1 a potential fluorescence sensor for these chemicals.

Abstract  The formation of volatile alkyl iodides other than methyl iodide during a serious nuclear reactor accident may have radiological significance. The hypothesis that radioactive alkyl iodides, other than methyl iodide, could form from paint solvents under the conditions of a serious nuclear accident in light water reactors (under boiling water reactor (BWR) and pressurised water reactor (PWR) conditions) was tested using stable elemental iodine, a gamma irradiator and gas chromatography equipment. It was found that methyl and isopropyl iodides were formed from the texanol ester, which is used in many modern water-based paints. Methyl, ethyl, propyl and butyl iodides were formed from a hydrocarbon solvent (white spirit) commonly used in paint products used in the past. These results suggest that further work on the formation and behaviour of the higher alkyl iodides (containing more than one carbon atom) under the conditions of a serious nuclear accident is justified.

Abstract  Portable power technologies for military applications necessitate the production of fuels similar to LPG from existing feedstocks. Catalytic cracking of military jet fuel to form a mixture of C₂-C₄ hydrocarbons was investigated using high-throughput experimentation. Cracking experiments were performed in a gas-phase, 16-sample high-throughput reactor. Zeolite ZSM-5 catalysts with low Si/Al ratios (≤25) demonstrated the highest production of C₂-C₄ hydrocarbons at moderate reaction temperatures (623-823 K). ZSM-5 catalysts were optimized for JP-8 cracking activity to LPG through varying reaction temperature and framework Si/Al ratio. The reducing atmosphere required during catalytic cracking resulted in coking of the catalyst and a commensurate decrease in conversion rate. Rare earth metal promoters for ZSM-5 catalysts were screened to reduce coking deactivation rates, while noble metal promoters reduced onset temperatures for coke burnoff regeneration.

Abstract  Two sampling sites representing the urban and suburban area of Chengdu, China were sampled and analyzed for selected chemicals to characterize the evolution of the chemical composition of fogwater. A trend of total organic carbon (TOC) > total nitrogen (TN) > total inorganic carbon (TIC) was observed for both sites. Variation of inorganic ions indicated that inorganic pollutants were not accumulated in the fog. Concentrations of n-alkanes (C11-C37) at the urban site ranged from 7.58 to 27.75 ng/mL while at the suburban site concentrations were 2.57-21.55 ng/mL. The highest concentration of n-alkanes was observed in the mature period of fog (393.12 ng/mL) which was more than ten times that in the fog formation period (27.83 ng/mL) and the fog dissipation period (14.87 ng/mL). Concentrations of Sigma15PAHs were in the range of 7.27-38.52 ng/mL at the urban site and 2.59-22.69 ng/mL at the suburban site. Contents of PAHs in the mature period of fog (27.15 ng/mL) > fog dissipation period (11.59 ng/mL) > fog formation period (6.42 ng/mL). Concentrations of dicarboxylic acids (C5-C9) ranged from 10.92 to 40.78 ng/mL, with glutaric acid (C5) as the dominant dicarboxylic acid. These data provide strong indications of the accumulation of certain organic chemicals of environmental concern in fog and fog water, and provide additional insights about processes in urban and suburban air acting on organic chemicals with similar physical chemical properties.

Abstract  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.

Abstract  The yield of cold neutrons from the cold moderator in the IBR-2M reactor is calculated for several hydrogenous materials at cryogenic temperature. The intramolecular bonds during the interaction with < 10 MeV neutrons are taken into account in the cross-section libraries for these materials. The moderator thickness optimizing the cold-neutron yield is analyzed. It is shown that taking account of the radiation effects the aromatic hydrocarbons (mixture of mesitylene and m-xylene) is the best material for use in IBR-2M cold moderators. The computational results for optimizing the complex IBR-2M moderators are presented.

Abstract  Water is the main deterioration factor of monuments and outdoor objects of the cultural heritage. The application of (super)hydrophobic siloxane coatings constitutes a promising method for monument protection and consolidation. In this study, the polymerization process, occurred because of the air humidity, of siloxane based (super)hydrophobic coatings is monitored at the molecular level using micro-Raman spectroscopy. Initially, we record the time evolution of changes in the structure of the commercially available pure poly(alkyl siloxane) Silres BS 290 (no solvent or nanoparticles) using micro-Raman spectroscopy. Then, the Raman study is extended to coatings prepared from solution of Silres BS 290 in white spirit. These coatings are hydrophobic according to contact angle measurements. Finally, Raman is employed to monitor the polymerization of two composite coatings prepared from dispersions of silica and tin oxide nanoparticles which were added in the siloxane solution. The resulting composite coatings exhibits superhydrophobic properties, according to contact angle measurements. Superhydrophobicity is interpreted in terms of a complex micro- and nanoscopic architecture, revealed using scanning electron microscopy. The aforementioned coatings are applied using a spraying method on glass and stone substrates, which have been used in monuments of the cultural heritage. The Raman results of this in situ analysis showed that certain peaks appearing in the high energy region of the spectra can be used as indices to monitor the polymerization process of the materials. (c) 2012 Elsevier B.V. All rights reserved.

Abstract  A two-dimensional heterogeneous computational fluid dynamics model was developed and validated to study the mass, heat, and momentum transport in a fixed-bed cylindrical adsorber during the adsorption of volatile organic compounds (VOCs) from a gas stream onto a fixed bed of beaded activated carbon (BAC). Experimental validation tests revealed that the model predicted the breakthrough curves for the studied VOCs (acetone, benzene, toluene, and 1,2,4-trimethylbenzene) as well as the pressure drop and temperature during benzene adsorption with a mean relative absolute error of 2.6, 11.8, and 0.8%, respectively. Effects of varying adsorption process variables such as carrier gas temperature, superficial velocity, VOC loading, particle size, and channelling were investigated. The results obtained from this study are encouraging because they show that the model was able to accurately simulate the transport processes in an adsorber and can potentially be used for enhancing absorber design and operation.

Abstract  The MixAlco process converts heterogeneous biomass feedstocks into gasoline, JP-8 and diesel via biochemical and chemical pathways, generating sludge in the effluent stream. The purpose of this article is to demonstrate how the generated sludge can be further converted into useful products such as hydrogen, methane and carbon monoxide, all produced in their maximum possible concentrations. Experiments were performed in a non-catalytic environment at atmospheric pressure conditions, studying synthesis gas and methane concentrations for temperatures in the range of 630/903-770/1043 degrees C/K and pretreated sludge feed rates in the range of 290-374 g/min. With an auger driven reactor system and the statistical response surface method, the highest possible synthesis gas composition was 43.9 +/- 3.36 vol% H-2/33.3 +/- 3.29 vol% CO at 740/1013 degrees C/K. The methane concentration was 20.3 +/- 2.99 vol%. The generated empirical models for both hydrogen and methane concentrations were significant but that for the carbon monoxide concentration behavior was not. As an input factor, temperature was significant but sludge feed rate was not. Mass and energy balances revealed process efficiency decreased with increase in temperature although the process could be self-sustaining even at the lowest process efficiency. Published by Elsevier B.V.

Abstract  Turbulent Jet Ignition is a prechamber initiated combustion system that can replace the spark plug in a standard spark ignition engine. The nozzle orifice is critical in a turbulent jet ignition system as it determines the shape and structure of the jet which acts as a distributed ignition source. In this paper, the effect of nozzle diameter and number was studied by performing combustion visualization and characterization for combustion of a premixed propane/air mixture initiated by a turbulent jet ignition system in a Rapid Compression Machine. Color images of the jet ignition process and visualization of the emission of the chemiluminesence of OH* and CH* radicals were performed. Several nozzle configurations were tested which expanded on the limited experimental results that were available in the literature. The performance of the turbulent jet ignition system based on the nozzle orifice diameter was characterized by considering the 0-10% and 10-90% burn durations of the pressure rise due to combustion. In general it was found that for near stoichiometric air to fuel ratios, a nozzle that produced more spatially distributed jets would result in faster combustion progression. However, at leaner conditions a smaller diameter nozzle that produced a faster and more vigorous jet was required to initiate combustion. The Reynolds number of the discharging jet for the single orifice cases was calculated and it was found that increasing the nozzle diameter increased the Reynolds number, and thus the turbulence for lambda = 1. The Reynolds number was not found to be sensitive to orifice diameter at the leaner condition of lambda = 1.25. Further characterization of the jet development leads to the conclusion that the jet was considered to be in the intermediate flow field; where the transient jet does not have enough time to become fully developed before it reaches the combustion chamber wall. (C) 2015 Elsevier Ltd. All rights reserved.

Abstract  We describe the redox functionalization of graphene oxide (GO) and the development of versatile amperometric biosensing platforms for clinically important analytes such as cholesterol ester, uric acid and glucose. Ferrocene (Fc) redox units were covalently tethered onto the GO backbone using diamine sigma spacers of different chain lengths (C3-, C6-, and C9-diamines). The functionalized GO (Fc-GO) displays a pair of redox peak corresponding to Fc/Fc(+) redox couple at ~0.225 V. The surface coverage and heterogeneous electron transfer rate constant of Fc-GO depends on the length of sigma spacer. Amperometric biosensors for cholesterol (total), uric acid and glucose have been developed by integrating Fc-GO and the respective redox enzymes with screen printed electrode. Fc-GO efficiently mediates the bioelectrocatalytic oxidation of the substrates in the presence of the redox enzymes. The spacer length of Fc-GO controls the bioelectrocatalytic response of the biosensing platforms. The sensitivity of the biosensors based on C9 sigma spacer is significantly higher than the others. The detection limit (S/N = 3) of the biosensors for cholesterol and uric acid was 0.1 μM and for glucose it was 1 μM. Excellent stability, reproducibility, selectivity and fast response time were achieved. Biosensing of cholesterol, uric acid and glucose in human serum sample is successfully demonstrated with the biosensors, and the results are validated with the clinical laboratory measurement.

Abstract  The first criticality of a new KZ-202 neutron moderator on the IBR-2M reactor is achieved. The moderator consists of thermal and cold units. The former is a room-temperature comb water moderator; the latter, a moderator using a mixture of aromatic hydrocarbons (mesitylene and m-xylene). The cold moderator is filled with granules of this mixture, which are supplied by a cold helium flow, and operates at 30 K. The combination of two units in one moderator makes it possible to simultaneously take the thermal and cold neutron spectra for extracted-beam spectrometers. The arrangement of the thermal and cold moderators is numerically optimized by the Monte Carlo method. The use of the cold moderator allows a 13-fold increase in the cold neutron intensity from its surface.

Abstract  Electrical characterisations of Mesitylene-2-boronic acid (MBA), Phenylboronic acid (PBA) and 1-Naphthylboronic acid (NBA) are investigated using C-f and I-V measurements. All materials are used to fabricate Langmuir-Blodgett (LB) thin film by vertical dipping method. Metal/LB film/Metal sandwich structure is prepared to investigate electrical properties of boron containing LB films. For evaluation of electrical measurements, the theoretical thickness is determined using ChemDraw software and experimental thickness value is calculated from surface plasmon resonance (SPR) curves. Dielectric measurements are used to determine the dielectric constant (epsilon) and to compare refractive index value which is determined from SPR results. The values of epsilon are determined as 2.79, 2.70, 2.82 for MBA, PBA and NBA respectively. The refractive indexes of three materials are calculated to be around 1.6. I-V results are used to study the conduction mechanism of these LB films. The low voltage region shows an ohmic characteristic for each LB film and conductivity values are calculated as 0.55 x 10(-11) S m(-1), 0.42 x 10(-11) S m(-1) and 3.62 x 10(-11) S m(-1) for MBA, PBA and NBA respectively. In the high voltage region of I-V curves that show Schottky type conduction mechanisms with the barrier heights estimated for each LB film as 0.77, 0.79 and 0.76 eV respectively.

Abstract  Acetone gas phase aldol condensation over bulk and carbon-supported Mg-Zr has been studied in this work. The condensation yields C6 (mainly mesityl oxide) and C9 (phorones, isophorones and mesitylene) compounds, depending on reaction temperature and distribution of acid and basic sites. The influence of the temperature (323-723 K) was studied, higher C9 selectivities being obtained at higher temperatures (close to 50%). The influence of the concentration and the distribution of basic and acid sites was analyzed by comparing the results obtained with the bulk Mg-Zr and with Mg-Zr supported on non-microporous carbonaceous materials: high surface area graphites (HSAG) and carbon nanofibers (CNF). In addition, two different preparation methods (dry impregnation and co-precipitation) were tested.

The performance of the catalysts is related to the distribution of acid and basic sites. Acid-basic pairs are needed for the acetone condensation, weak acidity for dehydration and cyclation reactions, and the strongest basicity for the condensation of mesityl oxide. (c) 2013 Elsevier B.V. All rights reserved.

Abstract  The article presents the bench test results of a fully instrumented, four cylinder, naturally aspirated, (60kW) direct injection (DI) diesel engine running on the normal (class C) diesel fuel (DF) and aviation-turbine (JP-8) fuel. The article addresses changes in engine performance and exhaust emissions resulting from the replacement of commercial diesel fuel with JP-8 fuel. Investigation and comparison of the effects of the cetane number improving additive on the autoignition delay, maximum heat release rate, maximum in-cylinder pressure, performance efficiency of an engine, and exhaust emissions were provided for sound analysis of the test results. The series of engine tests were conducted running alternately on the normal diesel fuel, JP-8 fuel, and JP-8 treated with 0.04, 0.08, 0.12, 0.16, and 0.24vol% of 2-ethylhexyl nitrate. Studies on the operating characteristics of an engine were carried out for 15-10%, 50 and 100% loads, and the two ranges of speed: 1,400 revolutions per minute (rpm), at which maximum torque occurs, and a rated speed of 2,200rpm. Use of JP-8 fuel suggested fuel energy savings and ecological benefits for medium (50%) and full (100%) loads mainly when running at a low speed of 1,400rpm. Autoignition delay, maximum heat release rate, maximum in-cylinder pressure, and nitrogen oxide (NOx) emissions decreased; however, the carbon monoxide (CO), hydrocarbon (HC) emissions, and the smoke opacity of the exhaust increased to a certain extent responding to the addition of 2-ethylhexyl nitrate to the JP-8 fuel. The brake-specific fuel consumption and brake thermal efficiency of a fully (100%) loaded engine changed little when running on treated JP-8-12 fuel at a rated speed of 2,200rpm. Analysis of the test results revealed that the cetane number improving additive can be considered as an effective but not the only measure to be applied for an intended use of aviation-turbine JP-8 fuel in ground-based diesel engines.