Simultaneous analysis of optical and mechanical properties of cross-linked azobenzene-containing liquid-crystalline polymer films

The photomechanical behavior of cross-linked azobenzene-containing liquid-crystalline polymer films was investigated by means of simultaneous measurement of their optical and mechanical properties. The connection between photoisomerization of the azobenzene moieties, photoinduced change in molecular alignment, photoinduced stress generation, and macroscopic bending was analyzed. Upon UV irradiation, the films exhibited bending due to gradient in cis-azobenzene content, and subsequent unbending when cis-azobenzene content became uniform throughout the film. The maximum photoinduced stress was generated in the same time scale as the time required to reach photostationary state in the cis-azobenzene concentration. The maximum values of photogenerated stress strongly depended on the crosslinker concentration, even if the azobenzene concentration and the cis-azobenzene content in the photostationary state were similar for all the polymer films. The stress is connected to the initial Young's modulus and also to the photoinduced change in birefringence of the polymer films. In addition, a significant photoinduced decrease in Young's modulus was for the first time observed in cross-linked azobenzene-containing liquid-crystalline polymers, which is likely to be an important factor in dictating their photomechanical behavior.     

Melt growth of multicrystalline SiGe with large compositional distribution for new solar cell applications

The melt-growth conditions to obtain SiGe multicrystals with microscopic compositional distribution are presented. These SiGe multicrystals are useful for new solar cells whose wavelength dependence of the absorption coefficient can be freely designed. The multicrystals with wide compositional distribution from Si to Ge can be grown by a melt growth technique such as the practical casting method. In this work, it was studied as to how much the micro- and macroscopic compositional distribution in SiGe multicrystals grown from binary Si–Ge melts could be controlled by the melt composition and the cooling process. Such SiGe multicrystals with wide distribution of the composition would also have wide distribution of the absorption coefficient, and could be hopeful for new solar cell applications using the practical casting method.     

Metabolism of (+)- and (-)-menthols by CYP2A6 in human liver microsomes

The in vitro metabolism of (+)-(1S,3S,4R) and (-)-(1R,3R,4S)-menthol enantiomers was examined by incubation with human liver microsomes, and the oxidative metabolites thus formed were analyzed using gas chromatography-mass spectrometry (GC-MS). The (+)- and (-)-menthols were found to be oxidized to the respective (+)-(1S,3S,4S)- and (-)-(1R,3R,4R)-trans-p-menthane-3,8-diol derivatives by human liver microsomal P450 enzymes. Cytochrome P450 (CYP) 2A6 was determined to be the major enzyme involved in the hydroxylation of (+)- and (-)-menthols by human liver microsomes on the basis of the following lines of evidence. First, of 11 recombinant human P450 enzymes tested, CYP2A6 catalyzed the oxidation of (+)- and (-)-menthols. Second, oxidation of (+)- and (-)-menthols was inhibited by (+)-menthofuran and anti-CYP2A6 antibody. Finally, (+)- and (-)-menthol activities were found to correlate with contents of CYP2A6 in liver microsomes of 9 human samples.     

Counter-Rotating Type Pump-Turbine Unit Stabilizing Momentarily Fluctuating Power from Renewable Energy Resources

It is difficult for renewable energy resources to provide constant power with excellent quality for the grid system. This serial research proposes a power stabilization system with a pumped storage to guarantee power quality and capacity, while the outputs from the energy resources are at unstable and/or fluctuating conditions. The power stabilization system with a counter-rotating type pump-turbine unit was prepared and operated at the pumping and the turbine modes. The unit composed of the tandem impellers/runners connected to the inner and the outer armatures of the unique motor/generator. The experiments have verified that this type pump-turbine unit is reasonably effective to stabilize momentarily/instantaneously the fluctuating power from the renewable energy resources.     

Brønsted Acid Generation over Alumina-Supported Niobia by Calcination at 1173 K

Alumina-supported niobium oxide promotes Friedel–Crafts reaction of benzyl alcohol and anisole effectively. The optimized condition of the catalyst was 16 wt% as Nb₂O₅ and calcination temperature of 1173 K. The catalyst exhibits the Brønsted acidity despite calcination at such high temperatures.     

Suppression of the oxidation of methyl linoleate encapsulated with the extract from defatted rice bran by a compressed hot water treatment

Bran extracts prepared by a compressed hot water treatment at 120, 150, and 180 °C for 7.5 min were used in association with maltodextrin for encapsulation of methyl linoleate. Mixtures of the bran extracts at 120 and 150 °C showed a higher emulsion-stabilizing ability than that at 180 °C. The bran extracts prepared at the higher temperature provided a higher oxidative stability as shown by the longer induction period for the oxidation of the encapsulated methyl linoleate. The induction periods of the encapsulated methyl linoleate using the bran extract prepared at 250 °C for 5 min as the aqueous phase were 3–6 times longer than those of the encapsulated methyl linoleate using water.     

Reaction kinetics of hydrothermal depolymerization of poly(ethylene naphthalate), poly(ethylene terephthalate), and polycarbonate with aqueous ammonia solution

Poly(ethylene naphthalate) (PEN), poly(ethylene terephthalate) (PET) and poly(carbonate) (PC) were depolymerized in a semi-batch reactor with a 0.6 M aqueous ammonia solution under hydrothermal conditions, at 433–553 K and 10 MPa, compared with aqueous alkaline (NaOH and KOH) solutions and water alone. The polymers studied were almost completely converted into monomers in an aqueous ammonia solution as well as aqueous NaOH and KOH solutions under hydrothermal conditions. The depolymerization reactions for the three polymers consisted of the initial induction stage, where the reactions proceeded very slowly, and the major depolymerization stage thereafter. The induction times were correlated with temperature. In the latter stage the overall depolymerization rate for each polymer was represented by 2/3-order reaction kinetics with respect to the amount of unreacted polymer, suggesting that the reaction occurred on the polymer surface. The depolymerization rates for PC with a 0.6 M aqueous ammonia solution were much faster than those with a 0.6 M aqueous NaOH solution.