Effects of adding B<Subscript>2</Subscript>O<Subscript>3</Subscript> as a flux on phosphorescent properties in synthesis of SrAl<Subscript>2</Subscript>O<Subscript>4</Subscript>: (Eu<Superscript>2+</Superscript>, DY<Superscript>3+</Superscript> phosphor

SrAl₂O₄: (Eu²⁺, Dy³⁺) phosphor was prepared by solid state reaction. B₂O₅ as a flux was added in SrAl₂O₄:(Eu ²⁺, Dy³⁺) in order to accelerate a solid state reaction. In this paper, the effects of B₂O₃ on the crystal structure and the phosphorescent properties of the material have been evaluated. The synthesized phosphor exhibited a broad band emission spectrum peaking at 520 nm, and the spectrum peak showed little effect by the B₂O₃ contents. The maximum afterglow intensity of the SrAl₂O₄: (Eu²⁺, Dy³⁺) phosphor was obtained at the B₂O₃ content of 5%. Adding the B₂O₃ caused uniform distortion to the crystal structure of the phosphor and resulted in reducing the lengths of a and c axes and Β angle of the SrAl₂O₄ crystal. The uniform distortion was accompanied with crystal defects which can trap the holes generated by the excitation of Eu²⁺ ions. The afterglow characteristic of the SrAl₂O₄: (Eu²⁺, Dy³⁺) phosphor was thus enhanced.     

Electrocatalytic oxidation of ethanol on Sn<Subscript>(1−<Emphasis Type="Italic">x</Emphasis>)</Subscript>Ir<Subscript>(<Emphasis Type="Italic">x</Emphasis>)</Subscript>O<Subscript>2</Subscript> electrodes in acid medium

The electrochemical oxidation of ethanol at Sn_(1−x)Ir _x O₂ electrodes (with x = 0.01, 0.05, 0.1 and 0.3) was studied in 0.1 mol L⁻¹ HClO₄ solution. Electrolysis experiments were carried out and the reaction products were analyzed by Liquid Chromatography. It was found that the amounts of the reaction products depended on the composition of the electrode. In situ infrared reflectance spectroscopy measurements were performed to identify the adsorbed intermediates and to postulate a reaction mechanism for ethanol electrooxidation on these electrode materials. As evidence, acetaldehyde and acetic acid were formed through a successive reaction process. Carbon dioxide was also identified as the end product, showing that the cleavage of the carbon–carbon bond occurred. These results indicate that the synthesized catalysts are able to lead to the total combustion of organic compounds. Analysis of the water bending band at different potentials illustrated its role at the electrode interface.     

Еlectrochemical hydriding/dehydriding of nanocrystalline Mg<Subscript>2−<Emphasis Type="Italic">x</Emphasis></Subscript>Sn<Subscript><Emphasis Type="Italic">x</Emphasis></Subscript>Ni (<Emphasis Type="Italic">x</Emphasis> = 0, 0.1, 0.3)

The electrochemical hydriding/dehydriding under galvanostatic conditions of nanostructured Mg_2-x Sn _x Ni (x = 0,0.1,0.3) were studied at different temperatures in the range 28–45 °C. The discharge capacity, cycle life and electrochemical impedance of the alloys were found to depend on the presence of Sn. Tin decreases the maximum electrochemical capacity, but essentially improves the cycle life of Mg₂Ni. Intensive corrosion of surface Mg was found to take place during the first 2–3 charge/discharge cycles to a much larger extent for Mg₂Ni, compared to the tin containing alloys. Sn decreases the electron density around the Mg atoms and therefore impedes magnesium oxidation. It was also found that Sn hampers charge transfer but reduces the hydrogen diffusion resistance in Mg₂Ni based alloys.     

Electrochemical oxidation of an acid dye by active chlorine generated using Ti/Sn<Subscript>(1−<Emphasis Type="Italic">x</Emphasis>)</Subscript>Ir<Subscript><Emphasis Type="Italic">x</Emphasis></Subscript>O<Subscript>2</Subscript> electrodes

The generation of active chlorine on Ti/Sn_(1−x)Ir _x O₂ anodes, with different compositions of Ir (x = 0.01, 0.05, 0.10 and 0.30 ), was investigated by controlled current density electrolysis. Using a low concentration of chloride ions (0.05 mol L⁻¹) and a low current density (5 mA cm⁻²) it was possible to produce up to 60 mg L⁻¹ of active chlorine on a Ti/Sn_0.99Ir_0.01O₂ anode. The feasibility of the discoloration of a textile acid azo dye, acid red 29 dye (C.I. 16570), was also investigated with in situ electrogenerated active chlorine on Ti/Sn_(1−x)Ir _x O₂ anodes. The best conditions for 100% discoloration and maximum degradation (70% TOC reduction) were found to be: NaCl pH 4, 25 mA cm⁻² and 6 h of electrolysis. It is suggested that active chlorine generation and/or powerful oxidants such as chlorine radicals and hydroxyl radicals are responsible for promoting faster dye degradation. Rate constants calculated from color decay versus time reveal a zero order reaction at dye concentrations up to 1.0 × 10⁻⁴ mol L⁻¹. Effects of other electrolytes, dye concentration and applied density currents also have been investigated and are discussed.     

Morphology and photoluminescence properties of phenolic epoxy resin coating on KH550-modified SrAl<Subscript>2</Subscript>O<Subscript>4</Subscript>: Eu<Superscript>2+</Superscript>, Dy<Superscript>3+</Superscript> powder in the presence of triarylsulfonium hexafluoroantimonate

In this study, the amino silane coupling agent (KH550)-modified SrAl₂0₄: Eu²⁺, Dy³⁺ phosphor powder coated with phenolic epoxy resin (EOCN) in the presence of triarylsulfonium hexafluoroantimonate catalyst was prepared using the combination of organic–inorganic composite dip-coating and UV curing coating methods. The results of SEM, TEM, and FTIR showed that the organic coating was a layer of compact membrane with a thickness of 20–50 nm, which can be named silane-modified epoxy monomer generated by the KH550 and the EOCN. Furthermore, it was observed that afterglow and spectrum properties of the coated phosphor powder had good long-afterglow luminescence properties, and revealed two emission peaks at 435 nm and 520 nm under the same excitation wavelength of 360 nm, respectively. More interesting, the emitting color of the coated sample was located in the area of cyan light on CIE1931 chromaticity diagram, which led to a slight blue shift rather than the yellow–green color of the pure SrAl₂0₄: Eu²⁺, Dy³⁺ phosphor powder.     

Structure and properties of solid solutions of La<Subscript>1 − <Emphasis Type="Italic">x</Emphasis></Subscript>Pr<Subscript><Emphasis Type="Italic">x</Emphasis></Subscript>BaCuFeO<Subscript>5 + δ</Subscript>

The effect of replacing lanthanum with praseodymium on the crystal chemistry parameters of solid solutions of La_{1 − x} Pr _x BaCuFeO_{5 + δ} has been investigated using X-ray powder diffraction analysis and IR spectroscopy. The thermal expansion, electroconductivity, and thermopower of these phases have been studied in air in the temperature range 300–1100 K. The values of linear thermal expansion coefficients (LTEC) of ceramics in different temperature ranges have been determined, and the values of electric transfer parameters in the above oxides have been calculated. It has been established that replacing lanthanum with praseodymium resulted in the compression of the elementary oxide unit La_{1 − x} Pr _x BaCuFeO_{5 + δ}, decrease in the content of labile oxygen in them (δ), decrease in nonmonotonic electroconductivity, increase in thermopower, decrease in LTEC, and difficulties in charge transfer in these phases.     

Highly selective and sensitive Th<Superscript>4+</Superscript>-PVC-based membrane sensor based on 2-(diphenylphosphorothioyl)-<Emphasis Type="Italic">N</Emphasis>′,<Emphasis Type="Italic">N</Emphasis>′-diphenylacetamide

A Th⁴⁺ ion-selective membrane sensor was fabricated from poly (vinyl chloride) (PVC) matrix membrane containing 2-(diphenylphosphorothioyl)-N′,N′-diphenyl acetamide (DPTD) as a neutral carrier, potassium tetrakis (p-chlorophenyl) borate (KTpClPB) as anionic excluder and o-nitrophenyloctyl ether (NPOE) as a plasticizing solvent mediator. The effects of the membrane composition, pH and additive anionic influence on the response properties were investigated. The sensor, comprising 30% PVC, 63% solvent mediator, 4% ionophore and 3% anionic additive demonstrates the best potentiometric response characteristics. It displays Nernstian behavior (15.2 ± 0.5 mV per decade) over the concentration range 1.0 × 10⁻²–1.0 × 10⁻⁶ M. The detection limit of the electrode is 6.3 × 10⁻⁷ M (∼140 ng/ml). The response time of the electrode is 30 s .The sensor can be used in the pH range 3.0–9.0 for about 6 weeks. The membrane sensor was used as an indicator electrode in the potentiometric titration of Th⁴⁺ ions with EDTA. It was successfully applied to the determination of thorium ions in binary mixture.     

Application of a Nickel-Bispidine Complex as Pre-Catalyst for C(<Emphasis Type="Italic">sp</Emphasis><Superscript>2</Superscript>)–C(<Emphasis Type="Italic">sp</Emphasis><Superscript>3</Superscript>) Bond Formations

Abstract  

In the present study, the nickel-catalyzed cross coupling of aryl halides with benzyl zinc bromides or dialkyl zinc reagents to create C(sp ²)–C(sp ³) bonds has been explored. As pre-catalyst the well-defined and easy-accessible (bispidine)Ni(NO₃)₂ complex has been applied. After investigation of different reaction parameters a broad scope of C(sp ²)–C(sp ³) bond formations were feasible under mild reaction conditions.     

Effect of Ni in palladium <Emphasis Type="Italic">β</Emphasis>-zeolite on hydroisomerization of <Emphasis Type="Italic">n</Emphasis>-decane

Bifunctional catalysts containing (0.1–0.5 wt%) Nickel and 0.1 wt% of Pd supported on H-β zeolite were synthesized by incipient wetness impregnation method and characterized by XRD, TEM, XPS, TPD and TPR techniques. The catalytic activity of Ni containing and Ni free Pd/H-β Catalysts was studied, and it was found that Ni up to a threshold value (0.3 wt% on β) produced increased the n-decane conversion and isomerization selectivity. When Ni content exceeds the threshold value, the conversion increases but isomerized products decrease. Moreover, Ni containing Pd/H-β showed increased sustainability and favored the protonated cyclopropane (PCP) intermediate mechanism in n-decane isomerization. The catalyst containing 0.3 wt% Ni 0.1 wt% Pd is adjudged as one performing better than other catalysts studied because of the isomerized mixture from it shows better octane number.     

Structural investigation of glasses in the <Emphasis Type="Italic">x</Emphasis>(0.16GaCh<Subscript>2</Subscript> · 0.84GeCh<Subscript>2</Subscript>) · (1 − <Emphasis Type="Italic">x</Emphasis>)(SbCh<Subscript>1.5</Subscript>) (Ch = S,Se) system

The structure of glasses in the x(0.16GaCh₂ · 0.84GeCh₂) · (1 − x)(SbCh_1.5) (Ch = S, Se) system has been investigated using Raman scattering. The structure of glasses is interpreted as a superposition of the following structural units: Ge(Ga)Ch_4/2, Ch_3/2Ge(Ga)-Ge(Ga)Ch_3/2, SbCh_3/2, and -Ch-Ch-, where Ch = S and Se. The change in the fraction of the corresponding structural units with a change in the glass composition has been analyzed.     

NMR Metabolomics of Thrips (<Emphasis Type="Italic">Frankliniella occidentalis</Emphasis>) Resistance in <Emphasis Type="Italic">Senecio</Emphasis> Hybrids

Western flower thrips (Frankliniella occidentalis) has become a key insect pest of agricultural and horticultural crops worldwide. Little is known about host plant resistance to thrips. In this study, we investigated thrips resistance in F ₂ hybrids of Senecio jacobaea and Senecio aquaticus. We identified thrips-resistant hybrids applying three different bioassays. Subsequently, we compared the metabolomic profiles of these hybrids applying nuclear magnetic resonance spectroscopy (NMR). The new developments of NMR facilitate a wide range coverage of the metabolome. This makes NMR especially suitable if there is no a priori knowledge of the compounds related to herbivore resistance and allows a holistic approach analyzing different chemical compounds simultaneously. We show that the metabolomes of thrips-resistant and -susceptible hybrids differed considerably. Thrips-resistant hybrids contained higher amounts of the pyrrolizidine alkaloids (PA), jacobine, and jaconine, especially in younger leaves. Also, a flavanoid, kaempferol glucoside, accumulated in the resistant plants. Both PAs and kaempferol are known for their inhibitory effect on herbivores. In resistant and susceptible F ₂ hybrids, young leaves showed less thrips damage than old leaves. Consistent with the optimal plant defense theory, young leaves contained increased levels of primary metabolites such as sucrose, raffinose, and stachyose, but also accumulated jacaranone as a secondary plant defense compound. Our results prove NMR as a promising tool to identify different metabolites involved in herbivore resistance. It constitutes a significant advance in the study of plant–insect relationships, providing key information on the implementation of herbivore resistance breeding strategies in plants. Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users.     

Hydrogen filter press electrolyser modelled by coupling Fluent<Superscript><Emphasis Type="Bold">®</Emphasis></Superscript> and Flux Expert<Superscript><Emphasis Type="Bold">®</Emphasis></Superscript> codes

Mass production of hydrogen is a major issue for the coming decades particularly to decrease greenhouse gas production. The development of fourth-generation high-temperature nuclear reactors has led to renewed interest for hydrogen production. In France, the CEA is investigating new processes using nuclear reactors, such as the Westinghouse hybrid cycle. A recent study was devoted to electrical modeling of the hydrogen electrolyzer, which is the key unit of this process. In this electrochemical reactor, hydrogen is reduced at the cathode and SO₂ is oxidized at the anode with the advantage of a very low voltage cell. This paper describes an improved model coupling the electrical and thermal phenomena with hydrodynamics in the electrolyzer, designed for a priori computational optimization of our future pilot cell. The hydrogen electrolyzer chosen here is a filter press design comprising a stack of identical cathode and anode compartments separated by a membrane. In a complex reactor of this type the main coupled physical phenomena involved are forced convection of the electrolyte flows, the plume of evolving hydrogen bubbles that modifies the local electrolyte conductivity, and all the irreversible processes that contribute to local overheating (Joule effect, overpotentials, etc.). The secondary current distribution was modeled with a commercial FEM code, Flux Expert^®, which was customized with specific finite interfacial elements capable of describing the potential discontinuity associated with the electrochemical overpotential. Since the finite element method is not capable of properly describing the complex two-phase flows in the cathode compartment, the Fluent^® CFD code was used for thermohydraulic computations. In this way each physical phenomenon was modeled using the best numerical method. The coupling implements an iterative process in which each code computes the physical data it has to transmit to the other one: the two-phase thermohydraulic problem is solved by Fluent^® using the Flux-Expert^® current density and heat sources; the secondary distribution and heat losses are solved by Flux-Expert^® using the Fluent^® temperature field and flow velocities. A set of dedicated library routines was developed for process initiation, message passing, and synchronization of the two codes. The first results obtained with the two coupled commercial codes give realistic distributions for the electrical current density, gas fraction, and velocity in the electrolyzer. This approach allows us to optimize the design of a future experimental device.     

<Emphasis Type="Italic">trans</Emphasis> Fatty Acid Content of Canadian Margarines Prior to Mandatory <Emphasis Type="Italic">trans</Emphasis> Fat Labelling

Dietary trans fatty acids (TFA) are of major concern because of their adverse effects on blood lipid levels and coronary heart disease. In Canada, margarines were significant sources of TFA during the 1980s and 1990s. However, this is expected to change with increased public awareness over their adverse health effects and the introduction of new legislature to include TFA content on the Nutritional Facts table of food labels. In this study, the TFA content of the top-selling 29 Canadian margarines, which represented 96.3% of the market share, was determined by capillary gas-liquid chromatography in order to assess the influence of regulatory development during the 3-year transition period between the announcement of new food labelling regulations in Canada that require mandatory declaration of the trans fat content in most pre-packaged foods in January 2003 and its enforcement on 12 December 2005. The 29 margarines included 15 tub margarines made from non-hydrogenated vegetable oils (NHVO-tub margarines), 11 tub margarines made from partially hydrogenated vegetable oils (PHVO-tub margarines) and three print margarines, which were also made from partially hydrogenated vegetable oils (PHVO-print margarines). The 15 NHVO tub-margarines accounted for 71% of the total margarine market share and generally contained less than 2% TFA (mean value 0.9 ± 0.3% of total fatty acids). The mean total TFA contents of PHVO-tub margarines and PHVO-print margarines, were 20.0 ± 4.5% and 39.6 ± 3.5%, and their market shares were 19.3 and 6.0%, respectively. Although during the last 10 years, increasing number of soft tub margarines that contained very little trans fats have been made available in Canada, the PHVO-tub- and -print margarines still contain high levels of trans fats similar to those margarines that were sold in the 1990s. The market share data suggest that the margarines prepared using NHVO and containing almost no TFA were preferred by Canadians over those margarines prepared using PHVO, even before the mandatory declaration of TFA content came into effect on 12 December 2005.     

Reaction selectivity of <Emphasis Type="Italic">rhizomucor miehei</Emphasis> lipase as influenced by monoacylation of <Emphasis Type="Italic">sn</Emphasis>-glycerol

Reaction selectivities were determined in multicompetitive reactions mediated by Rhizomucor miehei (RM) lipase at water activity of 0.19 in hexane. Saturated FA (C4–C18 even chain) and oleic acid (C18∶1) were reacted with a single alcohol, glycerol, or α-or β-MAG containing C4, C10, C16, or C18∶1 individually as alcohol cosubstrate. Similar patterns of broad FA selectivity toward C8–C18 FA were generally observed for esterification into specific acylglycerol (AG) pools with the different α/β-CX-MAG cosubstrates. Exceptions were enrichment of C18 in the MAG pool with α-C16-MAG substrate, and a general suppression of C4/C6 FA reactivity and a specific discrimination toward >C8 FA incorporation into the TAG pool, both for reactions with α-C10- and α-C16-MAG. RM lipase selectivity toward MAG was in descending order: β-C18∶1-MAG>α/β-C4-MAG∼β-C10-MAG∼β-C16-MAG>α-C18∶1-MAG >α-C10-MAG∼α-C16-MAG. Selectivity in channeling CX of the original CX-MAG substrates into higher AG species was in descending order: α-C10-MAG∼α-C16-MAG>β-C10-MAGβ-C16-MAG>α-C18∶1-MAG>β-C18∶1-MAG∼ α/β-C4-MAG. Aside from their characteristic FA selectivity, Burkholderia cepacia (PS-30) and RM lipases behaved similarly in terms of MAG selectivity as well as a general conservation of FA selectivity throughout the sequential steps of TAG assembly from FA and glycerol for processes designed to yield specifically structured TAG.     

Predicting coke quality on the basis of <Emphasis Type="Italic">CSR</Emphasis> and <Emphasis Type="Italic">CRI</Emphasis>: A review

Analysis of the regression equations proposed for the prediction of coke quality on the basis of CSR and CRI shows that some equations with relatively high correlation coefficients produce results inconsistent with experimental data and therefore require refinement. Equations that include characteristics calculated from the chemical composition of the ash and the physical constants of the oxides present (the molecular mass, the actual density, the melting point) lead to large errors and hence cannot be recommended.     

Immobilization of <Emphasis Type="Italic">α</Emphasis>-amylase from <Emphasis Type="Italic">Bacillus licheniformis</Emphasis> on developed support using microbial transglutaminase

α-amylase from Bacillus licheniformis was successfully immobilized on developed support, which was prepared by coating a chitosan-casein film on silica, at 20 °C, pH 6.0 for 5 hr with microbial transglutaminase (MTG) as the cross-linking factor. The optimal support was obtained when 1% chitosan and 1% casein were used in the coating mixture. The optimal condition for immobilization catalyzed by MTG was confined to be at MTG concentration of 15 U/mL, pH 6.0, reacting for 6 hr at 20 °C. The highest specific activity of immobilized α-amylase was achieved as 236 U/g. After immobilization, the obtained enzyme showed broader pH profile and maintained more than 70% of the original activity after 20 reuses.     

Protoplast from <Emphasis Type="Italic">β</Emphasis>-carotene-producing fungus <Emphasis Type="Italic">Blakeslea trispora</Emphasis>: Preparation,regeneration and validation

The effects of key parameters on the preparation and regeneration of protoplast from the β-carotene-producing fungus Blakeslea trispora were discussed in this paper, including the combination of various enzymes, mycelial age, digesting time and temperature, pH value, osmotic stabilizers, pretreatment, culture medium and culture method. Under the condition of mixed enzymes in osmotic stabilizer (0.6 M NaCl) combined with 2% lysozyme, 3% cellulase and 3% snailase, the highest protoplast yield, as high as 7.48×106 protoplasts/mL, was obtained when mycelial age was 60 h at pH 5.0–6.0 with digesting for 14–16 h at 28 °C. After purification of the obtained protoplasts, they were regenerated in PDA regenerative medium using bilayer plate culture method. To validate the usability of the protoplasts, a novel plasmid with green fluorescent protein (GFP) was used in transformation for easy visual observation. The results showed that the protoplasts prepared by the optimized method were active and applicable in further gene manipulation experiments. This work was presented at 13 ^th YABEC symposium held at Seoul, Korea, October 20–22, 2007.     

Temperature programmed desorption of <Emphasis Type="Italic">n</Emphasis>-hexane and <Emphasis Type="Italic">n</Emphasis>-heptane from MFI and FAU zeolites

TPD studies of n-hexane and n-heptane from NaX, Y and ZSM-5 (Na⁺ or H⁺ exchanged) in the experimental system with a TCD detector were performed, using pure He or He/n-alkane mixture as a carrier gas. The TPD profiles with one desorption peak for Y and two peaks for ZSM-5, measured using He/hydrocarbon mixture, were similar to the previously reported equilibrated thermodesorption results. TPD profiles were accurately fitted with a model based on the equilibrium control of the desorption and the adsorption functions derived from the Langmuir or dual site Langmuir isotherms.