Oxychlorination of methane over FeO<Subscript><Emphasis Type="Italic">x</Emphasis></Subscript>/CeO<Subscript>2</Subscript> catalysts

Methane activation through oxychlorination is in the spotlight due to the relatively mild reaction conditions at atmospheric pressure and in the temperature range of 450–550 °C. Although CO₂ is known to exhibit good activity for methane oxychlorination, significant amounts of by-products such as CO₂, CO and carbon deposits are produced during the reaction over CO₂. We investigated the effect of iron in FeO_x/CO₂ catalysts on methane oxychlorination. FeO_x/CO₂ with 3 wt% iron shows the maximum yield at 510 °C with 23% conversion of methane and 65% selectivity of chloromethane. XRD and H₂ TPR results indicate that iron-cerium solid solution was formed, resulting in the production of more easily reduced cerium oxide and the suppression of catalysts sintering during the reaction. Furthermore, the selectivity of by-products decreased more significantly over FeO_x/CO₂ than cerium oxide, which can be attributed to the facilitation of HCl oxidation arising from the enhanced reducibility of the former sample.     

SiO<Subscript><Emphasis Type="Italic">x</Emphasis></Subscript>/SiN<Subscript><Emphasis Type="Italic">y</Emphasis></Subscript> multilayers for photovoltaic and photonic applications

Microstructural, electrical, and optical properties of undoped and Nd³⁺-doped SiO _x /SiN _y multilayers fabricated by reactive radio frequency magnetron co-sputtering have been investigated with regard to thermal treatment. This letter demonstrates the advantages of using SiN _y as the alternating sublayer instead of SiO₂. A high density of silicon nanoclusters of the order 10¹⁹ nc/cm³ is achieved in the SiO _x sublayers. Enhanced conductivity, emission, and absorption are attained at low thermal budget, which are promising for photovoltaic applications. Furthermore, the enhancement of Nd³⁺ emission in these multilayers in comparison with the SiO _x /SiO₂ counterparts offers promising future photonic applications.     

Anisotropic Ti<Subscript><Emphasis Type="Italic">x</Emphasis></Subscript>Sn<Subscript>1-</Subscript><Subscript><Emphasis Type="Italic">x</Emphasis></Subscript>O<Subscript>2</Subscript> nanostructures prepared by magnetron sputter deposition

Regular arrays of Ti _x Sn_{1- x} O₂ nanoflakes were fabricated through glancing angle sputter deposition onto self-assembled close-packed arrays of 200-nm-diameter polystyrene spheres. The morphology of nanostructures could be controlled by simply adjusting the sputtering power of the Ti target. The reflectance measurements showed that the melon seed-shaped nanoflakes exhibited optimal properties of antireflection in the entire visible and ultraviolet region. In addition, we determined their anisotropic reflectance in the direction parallel to the surface of nanoflakes and perpendicular to it, arising from the anisotropic morphology.     

Photoluminescence characteristics of Cd<Subscript>1-<Emphasis Type="Italic">x</Emphasis></Subscript>Mn<Subscript><Emphasis Type="Italic">x</Emphasis></Subscript>Te single crystals grown by the vertical Bridgman method

In this paper, we report a systematic investigation of band-edge photoluminescence for Cd_1-x Mn _x Te crystals grown by the vertical Bridgman method. The near-band-edge emissions of neutral acceptor-bound excitons (labeled as L1) were systematically investigated as a function of temperature and of alloy composition. The parameters that describe the temperature variation of the energy were evaluated by the semiempirical Varshni relation. From the temperature dependence of the full width at half maximum of the L1 emission line, the broadening factors Γ(T) were determined from the fit to the data. The activation energies of thermal quenching were obtained for the L1 peak from the temperature dependence of the bound exciton peaks and were found to decrease with increasing Mn concentration.     

Effects of Cu<Subscript><Emphasis Type="Italic">x</Emphasis></Subscript>TiO<Subscript><Emphasis Type="Italic">y</Emphasis></Subscript> nanometer particles on biological toxicity during zebrafish embryogenesis

This study investigated the toxicity of Cu (1, 10, 15, and 25 mol%) loaded TiO₂ and pure TiO₂ nanometersized photocatalysts during the development of zebrafish embryogenesis. The hatch rate decreased in the Cu _x TiO _y nanoparticles exposed groups (10, 20 ppt) compared to pure TiO₂ nano-particles (10, 20 ppt) exposed or control groups. These Cu _x TiO _y and TiO₂ nanoparticles led to developing mutated embryos with abnormal notochord formation, no tail, damaged eyes and abnormal heart development. Exposure to Cu _x TiO _y and pure TiO₂ nanoparticles led to glutathione increase, catalase activity increase, GST increase and GSR increase than control. Penetration of the Cu _x TiO _y and pure TiO₂ nanoparticles to the embryo was also tested. It was observed that Cu _x TiO _y and pure TiO₂ nanoparticles penetrated into cells. Moreover Cu _x TiO _y penetrated into the skin, nerve and yolk sac epithelium cells on the zebrafish larvae as aggregated particles, which may induce the direct interaction between nanoparticles and cell to cause adverse biological responses. As a result, the Cu-loaded TiO₂ nanoparticles had the toxicity of zebrafish embryo and larvae in the water environment.     

Mechanistic Investigation of Co Containing NO<Subscript><Emphasis Type="Italic">x</Emphasis></Subscript> Traps

Co-containing NO _x storage and reduction catalysts were investigated to identify the mechanism of Co promotion. X-ray diffraction and temperature programmed reduction demonstrated that Co exists in a highly oxidized state (Co₃O₄) and that the surface oxygen could be removed from the catalyst a typical operating conditions around 300 °C. Electron microscopy showed that Co is more uniformly distributed over the catalyst surface, as compared to Pt, with particle sizes ranging between 20 and 80 nm. In situ IR studies illustrated that NO _x storage occurs on Co-containing NSR catalyst via formation of nitrites and nitrates as surface intermediates. Finally, it was found that, similar to Pt, the addition of Co to Ba catalysts enhances the nitrite to nitrate transition rate and also increases the overall formation of nitrates. Therefore, the promotional effect shown by Co is the result of the combination of increased NO to NO₂ oxidation and improved surface area for NO₂ spillover to the Ba storage sites.     

Preparing and studying Pt/WO<Subscript>3</Subscript>/ZrO<Subscript>2</Subscript> catalysts for the isomerization of <Emphasis Type="Italic">n</Emphasis>-heptane

The effect of the temperature of WO₃/ZrO₂ support calcination in the range of 700–1000°C on the phase composition, acid, and catalytic properties of Pt/WO₃/ZrO₂ catalysts is studied. Using ammonia TPD, it is found that calcination in the temperature range of 850–950°C results in the formation of strong acid sites that increase the yield of the target products of the reaction of n-heptane isomerization: high octane di- and trimethylsubstituted isomers. DRIFT is used to determine the role of catalyst calcination in an air flow plays in the formation of charged platinum atoms, which results in higher catalyst activity.     

Electrical behavior of MIS devices based on Si nanoclusters embedded in SiO<Subscript><Emphasis Type="Italic">x</Emphasis></Subscript>N<Subscript><Emphasis Type="Italic">y</Emphasis></Subscript>and SiO<Subscript>2</Subscript> films

We examined and compared the electrical properties of silica (SiO₂) and silicon oxynitride (SiO _x N _y ) layers embedding silicon nanoclusters (Sinc) integrated in metal-insulator-semiconductor (MIS) devices. The technique used for the deposition of such layers is the reactive magnetron sputtering of a pure SiO₂ target under a mixture of hydrogen/argon plasma in which nitrogen is incorporated in the case of SiO _x N _y layer. Al/SiO _x N _y -Sinc/p-Si and Al/SiO₂-Sinc/p-Si devices were fabricated and electrically characterized. Results showed a high rectification ratio (>10⁴) for the SiO _x N _y -based device and a resistive behavior when nitrogen was not incorporating (SiO₂-based device). For rectifier devices, the ideality factor depends on the SiO _x N _y layer thickness. The conduction mechanisms of both MIS diode structures were studied by analyzing thermal and bias dependences of the carriers transport in relation with the nitrogen content.     

(1<Emphasis Type="Italic">S</Emphasis>,3<Emphasis Type="Italic">R</Emphasis>)-<Emphasis Type="Italic">cis</Emphasis>-Chrysanthemyl Tiglate: Sex Pheromone of the Striped Mealybug, <Emphasis Type="Italic">Ferrisia virgata</Emphasis>

Derivatives of 2,2-dimethyl-3-(2-methylprop-1-enyl)cyclopropanecarboxylic acid (chrysanthemic acid) are classic natural pyrethroids discovered in pyrethrum plants and show insecticidal activity. Chrysanthemic acid, with two asymmetric carbons, has four possible stereoisomers, and most natural pyrethroids have the (1R,3R)-trans configuration. Interestingly, chrysanthemic acid–related structures are also found in insect sex pheromones; carboxylic esters of (1R,3R)-trans-(2,2-dimethyl-3-(2-methylprop-1-enyl)cyclopropyl)methanol (chrysanthemyl alcohol) have been reported from two mealybug species. In the present study, another ester of chrysanthemyl alcohol was discovered from the striped mealybug, Ferrisia virgata (Cockerell), as its pheromone. By means of gas chromatography–mass spectrometry, nuclear magnetic resonance spectrometry, and high-performance liquid chromatography analyses using a chiral stationary phase column and authentic standards, the pheromone was identified as (1S,3R)-(?)-cis-chrysanthemyl tiglate. The (1S,3R)-enantiomer strongly attracted adult males in a greenhouse trapping bioassay, whereas the other enantiomers showed only weak activity. The cis configuration of the chrysanthemic acid–related structure appears to be relatively scarce in nature, and this is the first example reported from arthropods.     

Using CFD for NO<Subscript><Emphasis Type="Italic">x</Emphasis></Subscript> emission simulation in a dual fuel boiler

The present work is aimed at reducing NO _x formation in a 250 MW dual fuel boiler by means of air staging and over-fire air. CFD simulations are performed to identify the best locations in the boiler walls to install air and fuel injectors. By installing injectors at these locations, it is possible to reduce NO _x production by more than 70% without increasing the amount of CO. This value is in good agreement with available data reported in the literature. Simulation results (gas species analysis and temperature) have been validated with real data taken at the full-scale boiler.     

Laboratory Evaluation of <Emphasis Type="Italic">Artemisia annua</Emphasis> L. Extract and Artemisinin Activity against <Emphasis Type="Italic">Epilachna paenulata</Emphasis> and <Emphasis Type="Italic">Spodoptera eridania</Emphasis>

Ethanolic extract of aerial parts of Artemisia annua L. and artemisinin were evaluated as anti-insect products. In a feeding deterrence assay on Epilachna paenulata Germ (Coleoptera: Coccinellidae) larvae, complete feeding rejection was observed at an extract concentration of 1.5 mg/cm² on pumpkin leaf tissue. The same concentration produced a feeding inhibition of 87% in Spodoptera eridania (Cramer) (Lepidoptera: Noctuidae). In a no-choice assay, both species ate less and gained less weight when fed on leaves treated with the extract. Complete mortality in E. paenulata and 50% mortality in S. eridania were observed with extract at 1.5 mg/cm². Artemisinin exhibited a moderate antifeedant effect on E. paenulata and S. eridania at 0.03–0.375 mg/cm². However, a strong effect on survival and body weight was observed when E. paenulata larvae were forced to feed on leaves treated at 0.03 and 0.075 mg/cm². Artemisia annua ethanolic extract of aerial parts at 1.5 mg/cm² showed no phytotoxic effect on pumpkin seedlings.     

Theory and simulation of photogeneration and transport in Si-SiO<Subscript><Emphasis Type="Italic">x</Emphasis></Subscript> superlattice absorbers

Si-SiO _x superlattices are among the candidates that have been proposed as high band gap absorber material in all-Si tandem solar cell devices. Owing to the large potential barriers for photoexited charge carriers, transport in these devices is restricted to quantum-confined superlattice states. As a consequence of the finite number of wells and large built-in fields, the electronic spectrum can deviate considerably from the minibands of a regular superlattice. In this article, a quantum-kinetic theory based on the non-equilibrium Green's function formalism for an effective mass Hamiltonian is used for investigating photogeneration and transport in such devices for arbitrary geometry and operating conditions. By including the coupling of electrons to both photons and phonons, the theory is able to provide a microscopic picture of indirect generation, carrier relaxation, and inter-well transport mechanisms beyond the ballistic regime.     

Effect of <Emphasis Type="Italic">Fabp1/Scp</Emphasis>-<Emphasis Type="Italic">2/Scp</Emphasis>-<Emphasis Type="Italic">x</Emphasis> Ablation on Whole Body and Hepatic Phenotype of Phytol-Fed Male Mice

Liver fatty acid binding protein (Fabp1) and sterol carrier protein‐2/sterol carrier protein‐x (SCP‐2/SCP‐x) genes encode proteins that enhance hepatic uptake, cytosolic transport, and peroxisomal oxidation of toxic branched‐chain fatty acids derived from dietary phytol. Since male wild‐type (WT) mice express markedly higher levels of these proteins than females, the impact of ablating both genes (TKO) was examined in phytol‐fed males. In WT males, high phytol diet alone had little impact on whole body weight and did not alter the proportion of lean tissue mass (LTM) versus fat tissue mass (FTM). TKO conferred on dietary phytol the ability to induce weight loss as well as reduce liver weight, FTM, and even more so LTM. Concomitantly TKO induced hepatic lipid accumulation, preferentially threefold increased phospholipid (PL) at the expense of decreased triacylglycerol (TG) and total cholesterol. Increased PL was associated with upregulation of membrane fatty acid transport/translocase proteins (FATP 2,4), cytosolic fatty acid/fatty acyl‐CoA binding proteins (FABP2, ACBP), and the rate limiting enzyme in PL synthesis (Gpam). Decreased TG and cholesterol levels were not attributable to altered levels in respective synthetic enzymes or nuclear receptors. These data suggest that the higher level of Fabp1 and Scp2/Scpx gene products in WT males was protective against deleterious effects of dietary phytol, but TKO significantly exacerbated phytol effects in males.     

Effect of <Emphasis Type="Italic">trans</Emphasis>8, <Emphasis Type="Italic">cis</Emphasis>10+<Emphasis Type="Italic">cis</Emphasis>9, <Emphasis Type="Italic">trans</Emphasis>11 Conjugated Linoleic Acid Mixture on Lipid Metabolism in 3T3-L1 Cells

Evidence suggests that minor isomers of conjugated linoleic acid (CLA), such as trans8, cis10 CLA, can elicit unique biological effects of their own. In order to determine the effect of a mixture of t8, c10+c9, t11 CLA isomers on selected aspects of lipid metabolism, 3T3-L1 preadipocytes were differentiated for 8 days in the presence of 100 μM linoleic acid (LA); t8, c10+c9, t11 CLA; t10, c12+c9, t11 CLA or purified c9, t11 CLA. Whereas supplementation with c9, t11 and t10, c12+c9, t11 CLA resulted in cellular triglyceride (TG) concentrations of 3.4 ± 0.26 and 1.3 ± 0.11 μg TG/μg protein, respectively (P < 0.05), TG accumulation following treatment with CLA mixture t8, c10+c9, t11 was significantly intermediate (2.5 ± 0.22 μg TG/μg protein, P < 0.05) between the two other CLA treatments. However, these effects were not attributable to an alteration of the Δ⁹ desaturation index. Adiponectin content of adipocytes treated with t8, c10+c9, t11 mixture was similar to the individual isomer c9, t11 CLA, and both the t8, c10+c9, t11 and c9, t11 CLA groups were greater (P < 0.05) than in the t10, c12+c9, t11 CLA group. Overall, these results suggest that t8, c10+c9, t11 CLA mixture affects TG accumulation in 3T3-L1 cells differently from the c9, t11 and t10, c12 isomers. Furthermore, the reductions in TG accumulation occur without adversely affecting the adiponectin content of these cells.     

Biosynthesis of (3<Emphasis Type="Italic">Z</Emphasis>,6<Emphasis Type="Italic">Z</Emphasis>,9<Emphasis Type="Italic">Z</Emphasis>)-3,6,9-Octadecatriene: The Main Component of the Pheromone Blend of <Emphasis Type="Italic">Erannis bajaria</Emphasis>

The hydrocarbons (3Z,6Z,9Z)-3,6,9-octadecatriene (3Z,6Z,9Z-18:H) and (3Z,6Z,9Z)-3,6,9-nonadecatriene (3Z,6Z,9Z-19:H) constitute the pheromone of the winter moth, Erannis bajaria. These compounds belong to a large group of lepidopteran pheromones which consist of unsaturated hydrocarbons and their corresponding oxygenated derivatives. The biosynthesis of such hydrocarbons with an odd number of carbons in the chain is well understood. In contrast, knowledge about the biosynthesis of even numbered derivatives is lacking. We investigated the biosynthesis of 3Z,6Z,9Z-18:H by applying deuterium-labeled precursors to females of E. bajaria followed by gas chromatography–mass spectrometry analysis of extracts of the pheromone gland. A mixture of deuterium-labeled [17,17,18,18-²H₄]-3Z,6Z,9Z-18:H and the unlabeled 3Z,6Z,9Z-18:H was obtained after topical application and injection of (10Z,13Z,16Z)-[2,2,3,3-²H₄]-10,13,16-nonadecatrienoic acid ([2,2,3,3-²H₄]-10Z,13Z,16Z-19:acid) or (11Z,14Z,17Z)-[3,3,4,4-²H₄]-11,14,17-icosatrienoic acid ([3,3,4,4-²H₄]-11Z,14Z,17Z-20:acid). These results are consistent with a biosynthetic pathway that starts with α-linolenic acid (9Z,12Z,15Z-18:acid). Chain elongation leads to 11Z,14Z,17Z-20:acid, which is shortened by α-oxidation as the key step to yield 10Z,13Z,16Z-19:acid. This acid can be finally reduced to an aldehyde and decarbonylated or decarboxylated to furnish the pheromone component 3Z,6Z,9Z-18:H. A similar transformation of 11Z,14Z,17Z-20:acid yields the second pheromone component, 3Z,6Z,9Z-19:H.     

<Emphasis Type="Italic">Santalum </Emphasis><Emphasis Type="Italic">insulare</Emphasis> Acetylenic Fatty Acid Seed Oils: Comparison within the <Emphasis Type="Italic">Santalum</Emphasis> Genus

The sandalwood kernels of Santalum insulare (Santalaceae) collected in French Polynesia give seed oils containing significant amounts of ximenynic acid, E-11-octadecen-9-oic acid (64–86%). Fatty acid (FA) identifications were performed by gas chromatography/mass spectrometry (GC/MS) of FA methyl esters. Among the other main eight identified fatty acids, oleic acid was found at a 7–28% level. The content in stearolic acid, octadec-9-ynoic acid, was low (0.7–3.0%). An inverse relationship was demonstrated between ximenynic acid and oleic acid using 20 seed oils. Results obtained have been compared to other previously published data on species belonging to the Santalum genus, using multivariate statistical analysis. The relative FA S. insulare composition, rich in ximenynic acid is in the same order of those given for S. album or S. obtusifolium. The other compared species (S. acuminatum, S. lanceolatum, S. spicatum and S. murrayanum) are richer in oleic acid (40–59%) with some little differences in linolenic content.     

Oxidation kinetics for <Emphasis Type="Italic">cis</Emphasis>-9,<Emphasis Type="Italic">trans</Emphasis>-11 and <Emphasis Type="Italic">trans</Emphasis>-10,<Emphasis Type="Italic">cis</Emphasis>-12 isomers of CLA

The autoxidation processes of the cis-9,trans-11 (c9,t11) and trans-10,cis-12 (t10,c12) isomers of CLA were separately observed at ca. 0% RH and different temperatures. The t10,c12 CLA oxidized faster than the c9,t11 isomer at all tested temperatures. The first half of the oxidation process of t10,c12 CLA obeyed an autocatalytic-type rate expression, but the latter half followed first-order kinetics. On the other hand, the entire oxidation process of c9,t11 CLA could be expressed by the autocatalytic-type rate expression. The apparent activation energies and frequency factors for the autoxidation of the isomers were estimated from the rate constants obtained at various temperatures based on the Arrhenius equation. The apparent activation energies for the CLA isomers were greater than those for the nonconjugated n−6 and n−3 PUFA or their esters. However, the enthalpyentropy compensation held during the autoxidation of both the CLA and PUFA. This suggested that the autoxidation mechanisms for the CLA and PUFA were essentially the same.     

Thermoelectric Properties of <Emphasis Type="Italic">x</Emphasis>PbTe/Yb<Subscript>0.2</Subscript>Co<Subscript>4</Subscript>Sb<Subscript>12</Subscript> Hot-Pressed Samples

The xPbTe/Yb_0.2Co₄Sb₁₂ compounds were prepared by the ball-milling and hot-pressed process. Electrical conductivity of the composite samples are reduced with a increase in PbTe content; and, their temperature dependence coefficients show the positive values. The maximum electrical conductivity of composite materials is ~80000 Sm⁻¹ at 800 K. The Seebeck coefficient (absolute value) of the composite material is obviously improved with an increase in the dispersed phase (PbTe) content; the Seebeck coefficient (absolute value) of the 10PbTe sample is ~260 μVK⁻¹ at 700 K, which increases by 13.6% relative to that of the Yb_0.2Co₄Sb₁₂ sample. The thermal conductivity of the composite samples is improved due to introduction of PbTe, and the thermal conductivity of the 10PbTe sample is ~3 Wm⁻¹ K⁻¹ at 550 K. The maximum value of ZT is 0.78 at 700 K for the 2.5PbTe sample.