TiNコーティングハイスドリルによるSUS304の低周波振動ドリル加工

In this paper, a friction test was conducted with a friction testing machine to examine the basic interaction phenomena (frictional force, frictional temperature etc.) resulting from adhesion or welding between the test piece (SUS 304) and TiN coating. For comparison, black oxide coated test pieces were employed. Beside, cutting characteristics (tool life, cutting force, drill wear, etc.) during the drilling of SUS 304 with TiN coated drills was investigated and the results were compared with these of cobalt HSS drills (JIS SKH 56). The experimental results revealed a marked difference in performance between both type of drills with TiN coated drills showing superiority in every domain. Moreover the experimental results were compared with those in drilling by cobalt HSS drills. From this study, it is found that cutting characteristic in drilling of SUS 304 by TiN coating drills is more superior to those by cobalt HSS drills

ポリカーボネートを用いたドリルの増減送り加工機構の検討

At present in strictly economic and environmental situations, the improvement of production efficiency and environmental bad influence is the actual subject in a drilling process. In this study, in order to solve the cutting mechanism during intermittently decelerated feed drilling with polycarbonate was investigated and the relation among the cutting force (thrust, torque), chip shape and breaking stress of chip etc. was discussed. The main results are as follows. (1) The torque force in case of intermittently decelerated feed drilling (F_f=2,3,4) nearly equal in comparison with conventional drilling (F_f=1) and the changed range of this torque varies approximately 20% because of a dynamic component due to the periodic fluctuation of the applied feed. (2) The thrust force in case of intermittently decelerated feed drilling (F_f=2,3,4) increases approximately 50% in comparison with conventional drilling(F_f=1) and the changed range of this thrust varies approximately 50～60% than that of F_f=1. (3) The change of chip thickness is not a rectangle, it is chevron. On intermittently decelerated feed drilling, there was a chip of the folded condition on the slow feed part. (4) In breaking test of the chip, the breaking power is lowered of intermittently decelerated feed drilling further than conventional drilling. The breaking position is different by intermittently decelerated feed ratio

Dysregulation of Gene Expression in the Artificial Human Trisomy Cells of Chromosome 8 Associated with Transformed Cell Phenotypes

A change in chromosome number, known as aneuploidy, is a common characteristic of cancer. Aneuploidy disrupts gene expression in human cancer cells and immortalized human epithelial cells, but not in normal human cells. However, the relationship between aneuploidy and cancer remains unclear. To study the effects of aneuploidy in normal human cells, we generated artificial cells of human primary fibroblast having three chromosome 8 (trisomy 8 cells) by using microcell-mediated chromosome transfer technique. In addition to decreased proliferation, the trisomy 8 cells lost contact inhibition and reproliferated after exhibiting senescence-like characteristics that are typical of transformed cells. Furthermore, the trisomy 8 cells exhibited chromosome instability, and the overall gene expression profile based on microarray analyses was significantly different from that of diploid human primary fibroblasts. Our data suggest that aneuploidy, even a single chromosome gain, can be introduced into normal human cells and causes, in some cases, a partial cancer phenotype due to a disruption in overall gene expression

Synaptic E3 Ligase SCRAPPER in Contextual Fear Conditioning: Extensive Behavioral Phenotyping of Scrapper Heterozygote and Overexpressing Mutant Mice

SCRAPPER, an F-box protein coded by FBXL20, is a subunit of SCF type E3 ubiquitin ligase. SCRAPPER localizes synapses and directly binds to Rab3-interacting molecule 1 (RIM1), an essential factor for synaptic vesicle release, thus it regulates neural transmission via RIM1 degradation. A defect in SCRAPPER leads to neurotransmission abnormalities, which could subsequently result in neurodegenerative phenotypes. Because it is likely that the alteration of neural transmission in Scrapper mutant mice affect their systemic condition, we have analyzed the behavioral phenotypes of mice with decreased or increased the amount of SCRAPPER. We carried out a series of behavioral test batteries for Scrapper mutant mice. Scrapper transgenic mice overexpressing SCRAPPER in the hippocampus did not show any significant difference in every test argued in this manuscript by comparison with wild-type mice. On the other hand, heterozygotes of Scrapper knockout [SCR (+/−)] mice showed significant difference in the contextual but not cued fear conditioning test. In addition, SCR (+/−) mice altered in some tests reflecting anxiety, which implies the loss of functions of SCRAPPER in the hippocampus. The behavioral phenotypes of Scrapper mutant mice suggest that molecular degradation conferred by SCRAPPER play important roles in hippocampal-dependent fear memory formation