1. The oxidation resistance of containing Ni-base alloy is superior to that of the alloy without . 2. The appearance of oxides of Ni-20Cr-20Fe-5Nb- alloy is similar to that of oxides in commercial PM1000 and MA754 alloy. 3. The oxides in ODS alloy are grown mainly at particle boundaries.

Using a developed high-frequency induction heated combustion method. the simultaneous synthesis and densification of WC-xvol.%Co() hard materials was accomplished using elemental powders of W, C and Co. A complete synthesis and densification of the materials was achieved in one step within a duration of 1min. The final relative densities of the composite were over 98.5% for all cases, under the applied pressure of 60 MPa and the induced current. The hardness of the composites decreases and the fracture toughness increases with increasing cobalt content. As the carbon to tungsten ration increases, the hardness increase, but the fracture toughness decreases. The maximum values for the fracture toughness and hardness are 15.1 (at 20vol.%Co, W:C=1:1), and 1928 (at 5vol.%Co, W:C=1:1.3), respectively. Therefore we concluded that the HFIHCS method. which can produce WC-xvol.%Co within 1 minute in one step is superior to conventional ones.

1) Using a developed high-frequency induction heated sintering method, the rapid densification of WC-Co hard materials was accomplished using ultra fine powders with 260 nm size within 1 minute. 2) The relative density of the composite was 99.5% for the applide pressure of 60MPa and the induced current for 90% output of total capacity. 3) The grain size of WC-Co hard materials is about 260nm and the average thickness of the binder phase determined is about 11nm. The fracture toughness and the hardness of this work 12 , respectively. 4) Using pressureless sintering, we produced dense WC-Co hard materials with a relative density of 97% without applying pressure.

In ultrastructure study of testis, Sertoli cells start to differentiate at 16 days of gestation. Transcripts of FSH receptor, IGF-I receptor, ER receptor and androgen receptor were highly and initially expressed at 16 day of gestation. As results of in situ PCR at 16 day of gestation, transcripts of FSH, IGF-I receptor were detected in Sertoli cells and spermatogonia, whereas the receptors of and androgen were detected in Sertoli cells. Therefore, expression of FSH and estrogen androgen, IGF-I and could play an important role during fetal and prepubertal testicular development by stage specific manner in mouse.