In vitro synthesis of polyhydroxyalkanoate catalyzed by class II and III PHA synthases: a useful technique for surface coatings of a hydrophobic support with PHA

In vitro synthesis of polyhydroxyalkanoates (PHAs) on a hydrophobic support, i.e. highly oriented pyrolytic graphite (HOPG), was performed using class II PHA synthase (PhaC1_Pp) from Pseudomonas putida and class III PHA synthase (PhaEC_Av) from Allochromatium vinosum. Using PhaC1_Pp and 3‐hydroxyoctanoyl‐CoA, a poly(3‐hydroxyoctanoate) [P(3HO)] film was formed on the hydrophobic support with a thickness of a few nanometers, as revealed by atomic force microscopy (AFM). A poly(3‐hydroxybutyrate) [P(3HB)] film was also formed using PhaEC_Av and 3‐hydroxybutyryl‐CoA. AFM observations of the HOPG surface during P(3HB) film formation revealed that polymerized P(3HB) covered HOPG surface within the reaction time, resulting in the formation of a homogeneous ultra‐thin film. This method of ultra‐thin PHA film formation on a hydrophobic support may be applicable to the surface‐coating technique of materials with biodegradable, bioabsorbable, and biocompatible PHAs. Copyright © 2009 Society of Chemical Industry     

Diosgenin present in fenugreek improves glucose metabolism by promoting adipocyte differentiation and inhibiting inflammation in adipose tissues

In obesity, adipocyte hypertrophy and chronic inflammation in adipose tissues cause insulin resistance and type‐2 diabetes. Trigonella foenum‐graecum (fenugreek) can ameliorate hyperglycemia and diabetes. However, the effects of fenugreek on adipocyte size and inflammation in adipose tissues have not been demonstrated. In this study, we determined the effects of fenugreek on adipocyte size and inflammation in adipose tissues in diabetic obese KK‐Ay mice, and identified the active substance in fenugreek. Treatment of KK‐Ay mice with a high fat diet supplemented with 2% fenugreek ameliorated diabetes. Moreover, fenugreek miniaturized the adipocytes and increased the mRNA expression levels of differentiation‐related genes in adipose tissues. Fenugreek also inhibited macrophage infiltration into adipose tissues and decreased the mRNA expression levels of inflammatory genes. In addition, we identified diosgenin, a major aglycone of saponins in fenugreek to promote adipocyte differentiation and to inhibit expressions of several molecular candidates associated with inflammation in 3T3‐L1 cells. These results suggest that fenugreek ameliorated diabetes by promoting adipocyte differentiation and inhibiting inflammation in adipose tissues, and its effects are mediated by diosgenin. Fenugreek containing diosgenin may be useful for ameliorating the glucose metabolic disorder associated with obesity.     

Effect of Embraced Lipid on the Gelatinization of Rice Starch

Quantitative evalution of starch-lipid interaction was attempted by means of amylography, the degree of gelatinization, iodine affinity, iodine color intensity, solubility and swelling power using isolated non-defatted, defatted, and re-embraced or impregnated starch with fatty acids, whose starch was isolated from non-glutinous rice. The data obtained support that characteristics of rice starch are greatly affected by a trace amount of embraced lipid. The saturated amount of lipid in the rice starch might be reasonably deduced to be about 1 % or less. This value estimated from set back and maximum viscosity in amylography is in good agreement with the data obtained already.     

Nb multilayer planarization technology for a subnanosecondJosephson 1K-bit RAM

A fabrication process for a Josephson 1-kb RAM (random access memory) has been developed using a Nb multilayer planarization technology. The technology consists of an etchback technique using 2000-molecular-weight polystyrene and SiO₂ for the junction layer and wiring layers, and a tapered edge etching technique for contact between individual wiring layers. Excellent planarity, wherein level differences in all step areas were reduced to less than 1/20th of their original values, was achieved. Appropriate RAM operation with 570-ps minimum access time and 13-mW power dissipation, were confirmed     

Flame retardant mechanism of polydimethylsiloxane material containing platinum compound studied by analytical pyrolysis techniques and alkaline hydrolysis gas chromatography

The flame retardant mechanism for silicone rubber induced by adding ppm order of a platinum compound, platinum (0)-1,3-divinyl-1,1,3,3-tetramethyldisiloxane complex was studied by analytical pyrolysis techniques and alkaline hydrolysis gas chromatography. The thermal degradation measurement of the flame retardant silicone rubber sample (FR-SR) indicated that a considerable amount of methane was evolved from the FR-SR sample at around 400-800 °C while formations of cyclic siloxanes were fairly suppressed in comparison with that from the control SR sample. On the other hand, on the gas chromatogram of the hydrolysis products from the FR-SR residue samples thermally treated over 400 °C, significant amounts of characteristic products reflecting the cross-linking structures generating from methylene-bridge and trifunctional siloxane structures in the polymer chains were observed. These results suggest that the thermal decomposition of the FR-SR material is strongly suppressed by the formation of the cross-linking structures induced by the platinum compound during combustion, which leads to its flame retardancy.     

Tunneling of quasiparticles between two weakly coupled systems of superfluid helium

Quasiparticle tunneling in a weakly coupled system of liquid helium is theoretically studied, in analogy with normal electron tunneling of superconductor junctions. Chemical potential difference in this case is to be created across the junction by a superfluid flow parallel to the junction. Calculation shows that a collimated beam of quasiparticles would show several divergences of tunneling current at specific angles of incidence or at specific values of superfluid velocity, while no divergence is expected for the integrated current, which is an important difference from the case of superconductor junctions.