Effects of starving treatment on the gravid females of N. californicus were investigated at 20°C and 85% RH. When the females were reared without prey and water just after they laid the first egg under the abundant prey condition, they laid 1.8 eggs and survived for 4.3 d. In order to investigate the process of oogenesis in the body of the starved females, females just after laying the first egg were reared for 0, 12, 24, 36, 48, 72, and 96 hr without prey and water, and were then prepared for internal observation. In the body of females of 0hrstarvation, an egg with eggshell and two oocytes were observed in the ventral and dorsal regions, respectively. Larger oocyte had 2 roundish nuclei and abundant yolk granules, and was enveloped with vitelline membrane. These 2 nuclei were not fused but were just conjugated. Smaller oocyte had a nucleus, but did not form yolk granules and vitelline membrane. Females of 12hrstarvation had an egg in the ventral region and an oocyte in the dorsal region of the body. Females of 24hr-starvation maintained an oocyte in the dorsal region of the body, but did not have an egg in the ventral region. The oocyte was filled with abundant yolk granules, and held 2 irregular-shaped nuclei. Females starved more than 36hr also maintained only an oocyte in the dorsal region of the body. Only an irregular-shaped nucleus was observed in the oocyte. These micrographs suggested that (1) gravid females maintained an oocyte in the dorsal region after laying 2 eggs during starving treatment, (2) the oocyte was not absorbed during starvation, (3) the oocyte advanced vitellogenesis and the fusion of 2 nuclei, and (4) the oocyte was not enveloped with eggshell and did not start embryogenesis. It is also assumed that the sperm penetrated into the oocyte without yolk granules, although the penetration was not observed in this study.

The MIM industry is currently focusing on parts that are used in automobiles and medical instruments. Many of the parts in these categories are very small and often not easy to machine because of its complex geometry. Therefore MIM is well suited for the production of these parts. We tested the sinterability of SUS316L ultra fine powders (3,4, 6, 8micron) produced by ATMIX high-pressure water-atomization, and it showed excellent results. A density of 97% theoretical was obtained by sintering at 1373K when using the ultra fine powder (3micron). Specifically, the finer the powder size, higher was the sintered density. The surface roughness and accuracy are also greatly improved with ATMIX ultra fine powder.