An XPS study of the passivity of a series of iron—chromium alloys in sulphuric acid

The composition and structure of passive films formed on a series of iron—chromium alloys in de-aerated 1M H₂SO₄ were quantitatively studied by XPS. The chromium content of passive film increased drastically at ca. 13 %Cr of the bulk alloy composition, whereas no composition change was found in the surface of the substrate alloy immediately under the passive film. The high corrosion resistance of iron—chromium alloys with high chromium content is attributed to the protective nature of hydrated chromium oxy-hydroxide, which is the main constituent of passive films on the alloys containing chromium of 12.5 at. % or more.     

Neutralization of Lipopolysaccharide by Heat Shock Protein in Pediococcus pentosaceus AK‐23

About 1000 species of bacteria are present in the human intestine. Some Gram‐negative bacteria such as Escherichia coli or Salmonella spp. among intestinal bacteria have lipopolysaccharide (LPS), which might induce inflammation of human intestines. Actually, LPS, especially its lipid A constituent, is toxic. Small amounts of LPS in bacteria cause inflammation of mucosa and other tissues in humans. Such bacteria may be regulated by beneficial lactic acid bacteria to maintain human health. Many lactic acid bacteria show cancer prevention activity and anti‐inflammatory activity in intestines. Recently, Pediococcus pentosaceus AK‐23 was isolated from fermentative vegetable pickles for neutralization of LPS. For this study, a protein for LPS neutralization was purified partly from P. pentosaceus AK‐23. For this study, a protein for LPS neutralization was purified partly from P. pentosaceus AK‐23, by ultrafiltration using a 300 kDa membrane and a 100 kDa membrane after cell wall digestion by lysozyme. Gel running blue native electrophoresis revealed the existence of a 217 kDa protein. The band of the protein having the ability to bind LPS on the gel was analyzed for amino acid homology. As the result, it is revealed as part of a subunit of heat shock protein (HSP). Furthermore, it displayed LPS binding or hydrophobic motifs. The protein neutralized LPS to release fatty acid as myristic acid and glucose from polysaccharide. These findings suggest that HSP in P. pentosaceus AK‐23 neutralizes LPS to decompose it compising fatty acid and polysaccharide.     

Use of single-strand conformation polymorphism of amplified 16S rDNA for grouping of bacteria isolated from foods

The grouping method for isolated strains from foods using single-strand conformation polymorphism (SSCP) after PCR amplification of a portion of 16S rDNA was developed. This method was able to group the strains from various food samples based on 16S rDNA sequence. As 97.8% of the isolated strains from various foods were grouped correctly, use of the PCR-SSCP method enables the prompt and labor-saving analysis of microbial population of food-derived bacterial strains. Advantages in speed and accuracy of bacterial population identification by the PCR-SSCP method have practical application for food suppliers and testing laboratories.     

In planta transformation of kenaf plants (Hibiscus cannabinus var. aokawa No. 3) by Agrobacterium tumefaciens

Kenaf was transformed by inoculation of Agrobacterium tumefaciens onto the meristems of young plants in pots. The transformation was demonstrated by three lines of evidence: a phenotypic inheritance from T(0) to T(1) plants, detection of the transgene in both T(0) and T(1) plants, and rescue of plasmids composed of T-DNA of the binary vector and flanking plant genomic DNA from T(1) plants.     

Post-mortem tenderisation of rainbow trout (Oncorhyncus Mykiss) muscle caused by gradual disintegration of the extracellular matrix structure

A histological study combined with a newly devised compression test was carried out to clarify the mechanism of the post-mortem tenderisation of rainbow trout (Oncorhyncus mykiss Walbaum) muscle. It is suggested that the integrity of the extracellular matrix structure is very important for the toughness of fish muscle. During chilled storage, the gradual disintegration of the extracellular matrix structure was clearly demonstrated by light microscopic observations after compression but little change was observed without it. It is therefore suggested that the post-mortem tenderisation of fish muscle is closely related to the gradual disintegration of the extracellular matrix structure after death.     

Fine structure of the dorsal lingual epithelium of the juvenile hawksbill turtle, Eretmochelys imbricata bissa

BACKGROUND: Various species of turtles are adapted to different environments, such as freshwater, seawater, and terrestrial habitats. Comparisons of histological and ultrastructural features of the tongue of the juvenile Hawksbill turtle, Eretmochelys imbricata bissa, with those of freshwater turtles should reveal some aspects of the relationship between the structure of the lingual epithelium and the environment. METHODS: The light microscope, scanning electron microscope and transmission electron microscope were used. RESULTS: Light microscopy revealed that the mucosal epithelium of the tongue was of the keratinized, stratified squamous type. Under the scanning electron microscope, no lingual papillae were visible on the dorsal surface of the tongue. Micropits and the thickening of cell margins were clearly seen on the surface of cells located on the outermost side. The transmission electron microscope revealed that the cells in the intermediate layer were gradually flattened from the basal side to the surface side, as were their nuclei. In the shallow intermediate layer, the cells were significantly flattened, and their nuclei were condensed or had disappeared. The cytoplasm contained keratohyalin granules, tonofibrils, free ribosomes, mitochondria, and rough endoplasmic reticulum. Numerous free ribosomes were attached to the surface of small keratohyalin granules. The cells of the keratinized layer were significantly flattened, and their nuclei had completely disappeared. Most of cytoplasm was filled with keratin fibers of high electron density. Keratin fibers of the shedding cells, which were located on the outermost side of the keratinized layer, appeared looser, and each fiber, which was somewhat thicker than the tonofibrils and tonofilaments, was clearly distinguishable. CONCLUSIONS: The lingual epithelium of the juvenile Hawksbill turtle differs significantly from that of the adult freshwater turtle, in spite of the similarity in gross morphology of the tongues of these species.     

Preparation of α,ω-bis(p-vinylbenzyl)-terminated polystyrene and α-methylstyrene tetramer

Summary Telechelic macromers composed of only hydrocarbon were prepared by the end-capping reactions of two-ended living polystyrenes and dianion of -methylstyrene tetramer with p-vinylbenzyl chloride. ,-bis(p-vinylbenzyl)polystyrene obtained was found to have a narrow molecular weight distribution and high functionality. In the end-capping reaction of the tetrameric dianion, the yield of ,-(p-vinylbenzyl)-methylstyrene tetramer was 84 % at most, profoundly depending on the concentration of the dianion. To isolate the functionalized tetramer, the fractional dissolution of a crude product was performed with H₂O/MeOH and the result was desirable.     

Formation and Crystallization in the Yttrium Aluminosilicate Glasses Containing Zinc Oxide

Formation of yttrium aluminosilicate glasses containing zinc oxide from batches melted at 1550°C was investigated. Densities, thermal expansion coefficients, and Vickers hardnesses were measured for some glasses. In a specific compositional region, crystals with a convex and pyramidal habit were observed on the glass surface. The crystal was identified as ZnAl₂O₄ (gahnite) which has a Moh's hardness number of ∼8.     

烧结钢的应力-弹性及塑性应变曲线的制作与评价

根据拉伸试验(TT)得到的应力-应变曲线和通过声音脉冲方法(APM)得到的声速,计算并比较了烧结钢的弹性模量(E)和泊松比(v).Err和vTT的值分别小于EAPM和vAPM,这是因为在烧结钢的应力-应变中不仅包含了弹性应变,而且也包含了塑性应变.利用由EAPM和vAPM的值计算得到的纵向和横向弹性应变,从纵向和横向应力-应变中分离出纵向和横向的塑性应变.在小应变时烧结钢没有显示线性应力-应变的情况下,可以很简单地由纵向塑性应力表中求出弹性极限或0.2%的屈服强度.对于同样的应力,每个样品的弹性应变和塑性应变的不同,可以由基于孔隙特征(孔隙的大小、形状、相互连接及微观结构的不同)的模型来解释.     

Disulfide bond formation in refolding of thermophilic fungal protein disulfide isomerase

Disulfide bond formation in the refolding of thermophilic fungal protein disulfide isomerase (PDI) was investigated. It was revealed that (i) a disulfide bond buried inside the molecule is preferentially formed and contributes to the thermal stability and the isomerizing power of PDI, and (ii) formation of disulfide bonds in active sites located on the molecular surface causes deformation of the optimum conformation resulting in a decrease in the thermal stability.