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.     

Al-Ti-B-RE细化剂对Al-7．0Si-0．55Mg合金显微组织和力学性能的影响

研究添加Al-5Ti-lB-RE细化剂对Al-7．0Si-0．55Mg（A357）合金的显微组织和力学性能的影响。先利用真空熔炼技术制各Al-7．0Si-0．55Mg合金,然后在Al-7．0Si-0．55Mg合金中加入不同成分的Al-5Ti-1B-RE中间合金。通过X射线衍射仪（XRD）、金相显微镜（OM）和扫描电子显微镜（SEM）对显微组织和拉伸试样的断口形貌进行观察。在室温下对合金的力学性能进行测试。观察Al-5Ti-1B-RE细化剂的形态以及内部结构,可以发现以TiB,为异质形核核心的TiAl3／Ti2Al20RE的壳层结构相。在Al-7．0Si-0．55Mg合金中加入Al-5Ti-1B-3．0RE细化剂后,抗拉强度会有明显提升,直到0．2％添加量时,抗拉强度会达到峰值。     

Cellulose nanofibrils as templates for the design of poly(l-lactide)-nucleating surfaces

The abilities of surface-grafted cellulose nanofibrils for the nucleation of poly(l-lactide) (PLLA) were investigated. Cellulose nanofibrils with a width of ∼3 nm were obtained from wood cellulose via the oxidation using 2,2,6,6-tetramethylpiperidiniyl-1-oxyl as a catalyst and successive mechanical treatment. The cellulose nanofibril surfaces were selectively modified with amine-terminated poly(ethylene glycol) chains, via simple ionic bonds. The PEG-grafted cellulose nanofibril/PLLA composite films were prepared using a solvent casting method with chloroform. The isothermal and non-isothermal crystallization kinetics of the PLLA in the composites was studied using differential scanning calorimetry and polarized optical microscopy. The PEG chains were densely immobilized on the surface of the cellulose nanofibril templates, which had extraordinarily large specific surface areas. As a result, the surface-PEG layers effectively increased the rate of crystallization of the PLLA in the composites. Because of the increased degree of crystallinity after the isothermal crystallization, the composites showed better heat resistance than neat PLLA.     

Mixture distribution measurement using laser induced breakdown spectroscopy in hydrogen direct injection stratified charge

Reduction in cooling loss due to the heat transfer from burning gas to the combustion chamber wall is very important for improving the thermal efficiency in hydrogen engines. The previous research has shown that the direct injection stratified charge can be a technique to reduce the cooling loss and improve thermal efficiency in hydrogen combustion. For effective reductions in cooling loss by the stratified charge, it is very important to know the relation between the fuel injection conditions and mixture distribution. The current research employs the laser induced breakdown spectroscopy as a method to measure the hydrogen concentration distribution in the direct injection stratified charge. Measurement of instantaneous local equivalence ratio by the method clears the characteristics of mixture formation in hydrogen direct injection stratified charge. This research also tries to actively control the mixture distribution using a split fuel injection.     

Fracture behavior of niobium by hydrogenation and its application for fine powder fabrication

Fracture behavior of pure niobium (Nb) by several hydrogenation procedures has been investigated to elucidate the fundamental mechanisms of hydrogen pulverization, which can then be used to produce fine Nb powders with high purity. Concentric cracks and microcracks were introduced in recrystallized Nb specimens, leading to pulverization, when they absorb hydrogen enough to form a large volume of the face-centered orthorhombic β-NbH phase. This hydride phase exhibits anisotropic expansion of Nb lattice and embrittlement. Thus, the fracture of Nb plates occurs in the following sequence: hydrogen absorption, the formation of the ordered hydride phase, strain generation arising from the phase transformation, and crack nucleation and propagation. The authors also show that Nb powders less than 1 μm were prepared by hydrogenation and ball-milling at a temperature below 203 K, in which hydrogen was removed by dehydrogenation at above 724 K. Thus, fine and contamination-free Nb powders can be effectively fabricated by using hydrogenation, ball-milling, and dehydrogenation procedures.     

Composition dependence of young’s modulus in Ti-V, Ti-Nb, and Ti-V-Sn alloys

The Young’s modulus of Ti-V and Ti-V-Sn alloys quenched from the β-phase region after solution treatment and cold rolling was investigated in relation to alloy compositions, microstructures, and constituent phases. The composition dependence of the Young’s modulus for quenched Ti-V binary alloys shows two minima of 69 GPa at Ti-10 mass pct V and 72 GPa at Ti-26 mass pct V. Between the two compositions, athermalω or stress-induced ω is introduced in retainedβ phase and increases Young’s modulus. That is, a low Young’s modulus is attained unless alloys undergoω transformation. In Ti-5 and -8 mass pct V, which under goα′ (hcp) martensitic transformation on quenching, the Young’s modulus further decreases by cold rolling, which can be reasonably explained by the formation ofα′ rolling texture. Comparing Young’s modulus in Ti-V binary alloy with that in Ti-Nb binary alloy, it is found that Young’s modulus is remarkably increased by athermal- or stress inducedω phase, and it shows a minimum when both martensitic andω transformation are suppressed during quenching in metastableβ alloys. The Sn addition to Ti-V binary alloy retards or suppresses athermal and stress-inducedω transformation, thereby decreasing Young’s modulus. Young’s modulus exhibits minimum values of 51 GPa in quenched (Ti-12 pct V)-2 pct Sn and of 57 GPa in cold-rolled (Ti-12 pct V)-6 pct Sn.     

Method for recovery of heading from motion

A new method for recovery of heading from motion is developed on the basis of Longuet-Higgins and Prazdny's algorithm [Proc. R. Soc. London Ser. B 208, 385 (1980)]. In the algorithm a radial virtual flow field is generated and the difference between the original velocity field and the virtual radial field is computed. The difference vectors, which are directed to the heading point in the projected plane, allow us to estimate the direction of heading. The simulations of the algorithm were performed, and it was shown that the method estimates the direction of heading accurately.     

Isolation and characterization of phototrophic bacteria growing in lighted upflow anaerobic sludge blanket reactor

Two strains of phototrophic bacteria were isolated from the effluent of a lighted upflow anaerobic sludge blanket (LUASB) reactor. Their 16S rRNA gene sequences and phenotypic characteristics suggested that two isolates were Rhodopseudomonas palustris and Blastochloris sulfoviridis strains.