Effects of the degree of unsaturation of coexisting triacylglycerols on cholesterol oxidation

In order to evaluate the effects of the degree of unsaturation of triacylglycerols on cholesterol oxidation, mixtures of purified sardine oil triacylglycerols (iodine value, IV=182.6) and cholesterol; of partially hydrogenated sardine oil triacylglycerols (IV=174.5) and cholesterol; and of fully hydrogenated sardine oil triacylglycerols (IV=92.0) and cholesterol were incubated at 25°C in the dark. The oxidative stability of the samples decreased with increasing degree of unsaturation of the triacylglycerols in the sample mixtures; the induction period for peroxide values (PV) of the sardine oil triacylglycerols and cholesterol was shorter than that of the partially hydrogenated sardine oil triacylglycerols and cholesterol. Certain polyunsaturated fatty acids (PUFAs) in the constituent fatty acids of sardine oil triacylglycerols started to decrease after a shorter induction period compared with that of the partially hydrogenated triacylglycerols. The prominent cholesterol oxides accumulated in the samples were 7β-hydroxycholesterol, 7-ketocholesterol, β-epoxide and cholestane triol. The tendency for accumulation of cholesterol oxides in the time course coincided with the changes in PV as well as the decrease in PUFAs. Cholesterol was oxidized in conjunction with autoxidation of coexisting fish oil triacylglycerols. Although lowering the degree of unsaturation of fish oil triacylglycerols was effective in prolonging the induction period of cholesterol oxidation, the rate of cholesterol oxidation in the cholesterol oxides' formation phase after the induction period was not affected by the difference in the proportion of highly unsaturated fatty acids in the natural and partially hydrogenated triacylglycerols of fish oils.     

Frame shuffling: a novel method for in vitro protein evolution

We describe 'frame shuffling', a novel method for preparing artificial protein libraries. With this method, a Y-family DNA polymerase known to introduce frame shift mutations at high rates is utilized to scramble the reading frames of a parental gene. The resultant progeny produce mutant proteins having segmental sequence changes. Such frame-shuffled mutant proteins exhibit physicochemical properties that differ from those of proteins obtained using conventional mutagenesis.     

Solvothermal syntheses of semiconductor photocatalysts of ultra-high activities

Thermal treatment of titanium(IV) butoxide dissolved in 2-butanol at 573 K under autogenous pressure (alcohothermal treatment) yielded microcrystalline anatase-type titanium(IV) oxide (TiO₂). Thermal treatment of oxobis(2,4-pentanedionato-O,O′)titanium (TiO(acac)₂) in ethylene glycol (EG) in the presence of sodium acetate and a small amount of water at 573 K yielded microcrystalline brookite-type TiO₂. Tungsten(VI) oxide (WO₃) powders of monoclinic crystal structure with high crystallinity were synthesized by hydrothermal treatment (HTT), at 523 or 573 K, of aqueous tungstic acid (H₂WO₄) solutions prepared from sodium tungstate by ion-exchange (IE) with a proton-type resin. Anatase and brookite TiO₂ products were calcined at various temperatures and then used for photocatalytic mineralization of acetic acid in aqueous solutions under aerated conditions and dehydrogenation of 2-propanol under deaerated conditions. Almost all the anatase-type TiO₂ samples showed the activities more than twice higher than those of representative active photocatalysts, Degussa P-25 and Ishihara ST-01 in both reactions. A brookite sample with improved crystallinity and sufficient surface area obtained by calcination at 973 K exhibited the hydrogen evolution rate almost equal to P-25. HTT WO₃ powders with various physical properties were used as photocatalyst for evolution of oxygen (O₂) from an aqueous silver sulfate solution. WO₃ powder of high crystallinity, e.g., IE-HTT-WO₃ synthesized at 573 K, gave much higher O₂ yield than commercially available WO₃ samples.     

Estimation of the Distribution of Enantiomers of γ-Decalactone and γ-Dodecalactone in Malt Whisky

Lactic acid bacteria generate precursors of γ-lactones, which contribute to sweet and fatty flavour, from unsaturated fatty acids. In this study the distribution of enantiomers of γ-decalactone and γ-dodecalactone in malt whiskies were studied using multi-dimensional GC in an effort to elucidate the mechanism of formation of these lactones. The enantiomeric excess of these lactones was within the range of −10 to 30%. Furthermore, racemic methyl-10-hydroxystearate was synthesized and optically resolved by chiral-phase HPLC. The chirality of γ-dodecalactone produced was dependent on the chirality of the hydroxy fatty acid or its methyl ester supplied as the substrate, based on the results of a series of experiments in which the acid or the ester was supplied to distiller's yeast.     

Long crack growth behavior of implant material Ti–5Al–2.5Fe in air and simulated body environment related to microstructure

The fatigue crack propagation behavior of Ti–5Al–2.5Fe with various microstructures for biomedical applications was investigated in air and in a simulated body environment, Ringer's solution, in comparison with that of Ti–6Al–4V ELI and that of SUS 316L stainless steel. The crack propagation rate, da/dN, of Ti–5Al–2.5Fe in the case of each microstructure is greater than that of the Widmanstätten structure in Ti–6Al–4V ELI in air whereas da/dN of Ti–5Al–2.5Fe is nearly equal to that of the equiaxed structure in Ti–6Al–4V ELI in air when da/dN is plotted versus the nominal cyclic stress intensity factor range, ΔK. da/dN of the equiaxed structure and that of the Widmanstätten structure in Ti–5Al–2.5Fe are nearly the same in air when da/dN is plotted versus ΔK. da/dN of Ti–5Al–2.5Fe is nearly equal to that of SUS 316L stainless steel in the Paris Law region, whereas da/dN of Ti–5Al–2.5Fe is greater than that of SUS 316L stainless steel in the threshold region in air, when da/dN is plotted versus ΔK. da/dN of Ti–5Al–2.5Fe or Ti–6Al–4V ELI is nearly the same in air and in Ringer's solution when da/dN is plotted versus the effective cyclic stress intensity factor range, ΔK_eff, whereas da/dN of Ti–5Al–2.5Fe or Ti–6Al–4V ELI is greater in Ringer's solution than in air when da/dN is plotted versus ΔK.     

Highly efficient and aberration-corrected spectrometer for advanced Raman spectroscopy

We designed an asymmetric Czerny-Turner-type spectrometer with a spectral resolution of approximately 1 cm(-1) and a focal length of 500 mm (F/4.1) to improve the aberration properties: (1) coma aberration was corrected by use of a particular incident angle for a condensing mirror based onShafer's equation, (2) astigmatism was corrected by use of a toroidal condensing mirror, (3) the optimum distance was found between a grating and condensing mirror so that the centered light and marginal light at the detector possess the same incident angles to the condensing mirror (the aberration is therefore excellently corrected over the whole detector surfaces), and (4) these optimal configurations are ensured in a wide wavelength between 400 and 800 nm by use of gratings with different grooves. Then the spectrometer was constructed, and the excellent optical properties were confirmed with aligned fiber images and Raman spectra from copper phthalocyanine.