탄소섬유로 보강한 에폭시 복합재료를 필라멘트 와인딩 공법으로 제조하고 이의 기계적 및 전기적 특성을 연구하였다. 사단자법으로 제작한 UD-CFRP의 전기비저항을 유리전이 온도 부근에서 온도의 함수로서 알아보았다. 실온에서 세로 전기비저항 ρa와 가로 전기비저항 ρc는 방향에 따른 강한 이방성을 보였으며 이들의 비는 약 1:3000이었다. UD-CFRP 시편의 세로 및 가로 전기비저항은 처리된 에폭시 물질의 유리전이 온도 Tg 아래에서는 온도에 선형으로 감소하는 거동을 보였다. 그러나 Tg 위에서 UD-CFRP의 가로 전기비저항은 금속과 같은 거동을 나타내며 온도의 지수승에 비례하여 증가하였다. 전기비저항이 양의 온도 계수를 갖는 메커니즘은 Tg 위에서 온도가 증가함에 따라 탄소섬유 사이의 접촉이 끓어져서 전하운반자의 깡총뛰기나 터널링이 감소하기 때문으로 생각된다. 세로방향의 dc 전도에 관한 활성화 에너지는 Tg 아래에서 0.005 eV이고, Tg 위에서는 0.08 eV이었다.

To investigate the modifying effect of Kwao Kreu, Pueraria mirifica (PM), we performed two kind of studies which are the non-surgical medium-term carcinogenicity study and the modulation of gap functional intercellular communication study. The first study, a non-surgical medium-term carcinogenicity bioassay was done to investigate the modifying effect of Kwao Kent, Pueraria mirifica (PM), a rejuvenating folk medicine from Thailand, on the male F344 rat liver. Specific pathogen free, male 6-week-old F344 rats were divided into ten groups. To induce hepatocarcinogenesis, those in all groups were given a single i.p. injection of DEN (200 mg/kg) and were received two i.p. injection of DGA (300 mg/kg) at the ends of weeks 2 and 5. Rats of group 3-6 were given sodium phenobarbital (PB 0.05 % in drink). A diet containing 10 mg/kg PM was given to group 2 during the post-initiation phase and to groups 4 and 5 during promotion and initiation phase, respectively. Group 6 was given the experimental diet alone throughout the experiment (8 weeks). Rats of group 7, 8, 9 and 10 were fed 1000 mg/kg PM in the same manner as group 2, 4, 5 and 6. All animals were sacrificed at 8 weeks after DEN administration. Result of the iimmunohistochemical staining of the glutathione S-transferase placental form (GST-p) indicated that the numbers and areas of the preneoplastic leisions were not significantly changed in all PM treatment group comparing to control group. A.Iso the numbers and areas of GST-p positive foci among group 7, 8, 9 and 10 were not significantly changed in comparing to control group. To study the effect of PM on the modulation of gap functional intercellular communication, the present study was performed scrape-loading dye transfer (SL/DT) assay in human keratinocytes. The results showed that PM could not modulate GJIC. These results indicate that Pueraria mirifzca may have no carcinogenic effects on experimental hepatocarcinogenesis in rats and gap functional intercellular communication in human keratinocyte.

This study was carried out to evaluate the irritant potential of P-toothpaste in hamster cheek pouch. The test materials were applied once at the beginning of this study into right pouches of hamsters and maintained for 14 days. Animals were administered with P-toothpaste, Bamboo salt toothpaste, D.W. and control solution, respectively. In order to evaluate the irritant potential in mucosa of hamster cheek pouch, we observed clinical signs, mortality, body weights and gross and histopathological findings for 14 days. In all groups, there were neither dead animals nor significant changes of body weights. In addition, there were no differences between D.W. and Ptoothpaste treated group in gross and histopathological findings. Therefore, these results suggest that there was little irritant potential of P-toothpaste in hamster cheek pouch.