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.     

Microstructure and properties of various fluorine-containing SiAlON ceramics synthesized by HIPing

An attempt was made to prepare various F-doped β-, O-, X-, and -SiAlONs from a mixture of Si₃N₄, SiO₂, Al₂O₃, AlN, or Y₂O₃ using AlF₃ or topaz as the fluorine source by HIPing at 1500–1800°C and 150 MPa. The phases were identified and the z, x, and m/n values determined for β-, O-, and -SiAlONs by X-ray diffraction. When AlF₃ was used, a single phase ceramic (O-SiAlON) was produced from a mixture of -Si₃N₄ and SiO₂ at 1500°C, with a mixture of O- and β-SiAlONs formed at 1700°C. A mixture of -Si₃N₄, AlN, and Y₂O₃ with AlF₃ produced β-/Y--SiAlON ceramics at 1730°C. The use of topaz produced the β-SiAlON ceramic with a trace of mullite from a mixture of -Si₃N₄ and AlN at 1770°C and mixed phase β-/O-SiAlON ceramics from -Si₃N₄ and SiO₂ at 1700°C. Single phase X-SiAlON could not be obtained under the present conditions. The microstructures of the single phase O- and β-SiAlON ceramics and the β-/Y--SiAlON mixture showed the growth of O- and β-SiAlON and Y--SiAlON crystals with hexagonal and/or long rod-like or platy shapes in a matrix of F-containing glassy phase. The compositions of the SiAlON crystals and the glass phase were semi-quantitatively determined by EDX; the total glass phase was estimated by a quantitative Rietveld XRD powder method. The F-doped β-SiAlON ceramics showed better corrosion resistance towards NaCl vapor and lower Vickers hardnesses.     

Preparation of regioisomers of structured TAG consisting of one mole of CLA and two moles of caprylic acid

TAG (MLM) with medium-chain FA (MCFA) at the 1,3-positions and long-chain FA (LCFA) at the 2-position, and TAG (LMM) with LCFA at the 1(3)-position and MCFA at 2,3(1)-positions are a pair of TAG regioisomers. Large-scale preparation of the two TAG regioisomers was attempted. A commercially available FFA mixture (FFA-CLA) containing 9-cis, 11-trans (9c, 11t)- and 10t,12c-CLA was selected as LCFA, and caprylic acid (C₈FA) was selected as MCFA. The MLM isomer was synthesized by acidolysis of acyglycerols (AG) containing two CLA isomers with C₈FA: A mixture of AG-CLA/C₈ FA (1∶10, mol/mol) and 4 wt% immobilized Rhizomucor miehei lipase was agitated at 30°C for 72 h. The ratio of MLM to total AG was 51.1 wt%. Meanwhile, LMM isomer was synthesized by acidolysis of tricaprylin with FFA-CLA: A mixture of tricaprylin/FFA-CLA (1∶2, mol/mol) and 4 wt% immobilized R. miehei lipase was agitated at 30°C for 24 h. The ratio of LMM to total AG was 51.8 wt%. MLM and LMM were purified from 1,968 and 813 g reaction mixtures by stepwise short-path distillation, respectively. Consequently, MLM was purified to 92.3% with 49.1% recovery, and LMM was purified to 93.2% with 52.3% recovery. Regiospecific analyses of MLM and LMM indicated that the 2-positions of MLM and LMM were 95.1 mol% LCFA and 98.3 mol% C₈ FA, respectively. The results showed that a process comprising lipase reaction and short-path distillation is effective for large-scale preparation of high-purity regiospecific TAG isomers.     

Photoelectronic displacement sensor with nanometre resolution

The design of an ultraprecision displacement sensor with sub-nanometre resolution is proposed for the use of ultraprecision technologies. The sensor is based on the highly sensitive detection of power change at a specific point in light reflected from an object surface when the surface is subject to a small displacement. The sensor consists of a single light source, the reflective object and reference surfaces, optical fibre bundles for tranmission of the illuminating and the reflected light, and the photodiode set-up. In operation, the object and the reference surfaces are illuminated by light transmitted through the optical fibre bundle from the single light source. The reflected light from both surfaces is then transmitted through the optical fibre bundle to two individual but equivalent photodiodes. By using a differential amplifier, the diodes give a highly sensitive displacement signal which is included in the total signal of the reflected light. The sensor proposed has some distinctive features in its performance, such as non-contact measurement, a high resolution of 0.5 nm, a wide working range of about 30 μm within 5% linearity, and the sufficient stability of 1 nm in 20 s for specific research purposes.     

Mechano-electrochemistry of a passive surface using an in situ micro-indentation test

Depassivation–repassivation of iron surfaces in boric–borate solutions were investigated by using the micro-indentation test. A pair of current peaks due to repair of the passive film following rupture of the film were observed during a series of indenter drives, i.e., loading and unloading of the indenter. The shape of the current peak depended on environmental conditions (conductivity and pH of the solution) and substrate conditions (mechanical processing history, alloyed element) as well as indentation conditions (repetition, maximum depth, and maximum load). Plastic deformation of the surface was accompanied by surface depassivation, while no depassivation occurred during the elastic deformation, indicating that the passive film on iron has a ductile property. The solution conditions did not affect the scale of depassivation but affected the rate of repassivation. Dislocations in the substrate made surface depassivation difficult but enhanced reactivity during the repassivation. The test also revealed that type-312L stainless steel has high corrosion resistance in a concentrated NaCl solution.     

Study of drive system for linear induction motor using magnetic energy recovery switch

This paper proposes a power supply suitable for driving linear induction motors. The power supply consists of a voltage source inverter (VSI) and a magnetic energy recovery switch (MERS). Circuit configuration and operation principles of the power supply are described. Power factor correction by MERS can increase the output power. Technical advantages of using MERS compared with increasing the rated voltage of VSI are discussed. Some experiments with a linear induction motor were conducted. The results confirm that MERS can reduce the capacity of the VSI or increase the output with the same VSI capacity. The number of devices and magnitude of losses are evaluated on a large‐scale drive system. A half‐bridge type of MERS is provided and discussed. The half‐bridge MERS mitigates disadvantages of using MERS. © 2009 Wiley Periodicals, Inc. Electr Eng Jpn, 169(4): 65–74, 2009; Published online in Wiley InterScience ( www.interscience. wiley.com ). DOI 10.1002/eej.20832     

Highwall Stability due to Punch Mining at Opencut Coal Mines

Conventional highwall mining extracts coal with an auger machine or a continuous miner from exposed seams at the base of opencut or strip operations. However, under poor strata and high stress conditions, highwall mining cannot be conducted due to pillar and roof failures. In such cases, punch highwall mining is more effective than the conventional highwall mining. This paper describes conventional highwall mining and punch highwall mining systems and discusses the stability of the highwall due to punch highwall mining at opencut coal mines.     

Fabrication and operation limit of lead-free PTCR ceramics using BaTiO3–(Bi1/2Na1/2)TiO3 system

The electric properties of BaTiO₃–(Bi_1/2Na_1/2)TiO₃ (BT–BNT) solid solution ceramics were studied as a lead-free PTCR (positive temperature coefficient of resistivity) thermistor material usable over 130°C. For determining the maximum switching temperature T _s, the phase diagram of BT–BNT binary system was clarified. Two semiconductorization processes and their electric properties are described. The lanthanum(La)-doped BBNT ceramics sintered in air still showed dielectric behaviors, but the niobium(Nb)-doped ones had a low resistivity at room temperature, ρ _RT, on the order of 10³ Ωcm and showed a PTC behavior. Sintering under a low O₂ atmosphere produces BT–BNT ceramics with less than 10² Ωcm compared to those prepared in air. Our current research produced the BBNT ceramics with T _s values around 210°C by increasing the (Bi_1/2Na_1/2) content in the ceramics.     

Delay of nuclear maturation and reduction in developmental competence of pig oocytes after mineral oil overlay of in vitro maturation media

Steroid hormones, such as progesterone, oestrogen, androgen and meiosis activating sterols, are secreted from cumulus cells that are stimulated by gonadotrophins during maturation of oocytes in vitro. These steroid hormones may be absorbed by mineral oil or paraffin oil; however, in vitro maturation of pig oocytes is commonly performed using medium covered by oil. In this study, high concentrations of progesterone, oestradiol and testosterone were detected in the culture medium after pig cumulus-oocyte complexes (COCs) were cultured with FSH and LH for 44 h in medium without an oil overlay. However, high concentrations of these steroid hormones were not detected in medium when COCs were cultured with the mineral oil overlay. When high concentrations of these steroid hormones were secreted by COCs, germinal vesicle breakdown (GVBD) and the activation of p34(cdc2) kinase and mitogen-activated protein (MAP) kinase in oocytes occurred earlier in comparison with oocytes cultured in medium covered with mineral oil. Moreover, a decrease in p34(cdc2) kinase activity during meiotic progression beyond metaphase I was observed in oocytes cultured in conditions under which high concentrations of steroid hormones were secreted by COCs. In addition, the rate of development to the blastocyst stage after IVF was higher in oocytes matured in medium without an oil overlay. These adverse effects of oil may be explained by absorption by the oil of cumulus-secreted steroids or by the release of toxic compounds into the medium.