An atmospheric controlled IH FPP (Induction Heating and Fine Particle Peening) treatment system was developed. Using the system, the surface of ordinary structural steel was modified with Cr shot particle at room temperature, 500°C, 700°C and 900°C in atmosphere of either argon and air. The treated surfaces were characterized using a scanning electron microscope (SEM), an energy dispersive X ray spectrometer (EDX), an X ray diffractometer (XRD) and an X ray photoelectron spectroscope (XPS). In the case of the specimen treated in argon atmosphere, a relatively thick and uniform Cr rich layer was formed at the surface. The thickness of the layer was changed with an increase in temperature, the higher the temperature, the thicker the layer. In the case of the specimen treated in air, however, an oxidized scale was formed on the treated surface instead of a Cr rich layer. The results of the experiments prove that atmospheric controlled IH FPP treatment successfully creates a Cr rich surface layer. The specimen treated by atmospheric controlled IH FPP showed higher corrosion resistance compared to that of the untreated specimen, the higher the thickness of the Cr rich layer, the higher the corrosion resistance.

Starch is an abundant carbohydrate widespread in plants. This high energy polysaccharide is preserved in the storage tissues, such as seeds. In the germination of plant seeds, the starch is degraded by several hydrolytic enzymes (α amylase, β amylase, debranching enzyme and α glucosidase), followed by conversion to the biological materials and energy necessary for growth. 1) In plant seeds, starch exists as practically insoluble polysaccharide called starch granules or raw starch. Therefore, the pathway of starch degradation in the germination stage has been generally considered as follows. 2)α Amylase is a key enzyme attacking the starch granules initially to liberate soluble dextrin. Produced dextrin is hydrolyzed by the further action combined with α amylase, β amylase and debranching enzyme to form oligosaccharides such as maltose. Finally, α glucosidase converts the oligosaccharides to glucose. Among these starch degrading enzymes α amylase has been considered to be the exclusive enzyme capable of hydrolyzing the starch granules, while the other enzymes were not. However, it had been reported that plant α glucosidases exhibited the ability to attack soluble starch effectively, 3,4) which suggested that α glucosidase hydrolyzed not only oligosaccharides such as maltose but starch as well in plant seeds. Recently, barley, 5,6) millet 7,8) and rice 9,10) α glucosidases were found to be capable of degrading the starch granules. The combination of α glucosidase and α amylase exhibited the synergism of degradation of starch granules. 5,6,11) It is of interest to learn the α glucosidase mediated starch metabolism in the germination stage. The first section of this article introduces our molecular level analysis on the degradation of starch granules catalyzed by plant α glucosidase.In the second section, we describe the multiple formation mechanism of rice α glucosidases observed in the ripening and germination stages. α Glucosidases, which are synthesized in the ripening stage and preserved in dry seeds, are important in starch metabolism, since these enzymes hydrolyze starch granules before attacking by α amylase. Certain α glucosidase isozymes, which are expressed in the early stage of germination, also hydrolyze starch granules. It is valuable to learn the expression systems of α glucosidases in the dry seeds and germinating seeds. In both seeds, there were several enzymes, of which the expression feature differed by variety of rice, requiring more precise analysis to understand the contribution of each enzyme to starch metabolism. The second section of this article introduces the mechanism for the formation of rice α glucosidase isoforms and isozymes as well as their characteristics elucidated using purified en- Abstract: In germination of plant seeds, storage starch is principally degraded by the combination of amylolytic enzymes. As starch is an insoluble granule, a conventional view of the degradation pathway is that the initial attack is performed by α-amylase having the starch granule-binding ability. Pla...