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Ichida, Miho,Kataoka, Akemi,Tsushima, Ruriko,Taguchi, Tetsuya Asian Pacific Journal of Cancer Prevention 2015 Asian Pacific journal of cancer prevention Vol.16 No.9
Background: Low-dose oral contraceptives (OC) were approved by the Japanese Ministry of Health, Labor and Welfare in 1999, yet despite their contraceptive and non-contraceptive health benefits, only 5% of the target population use them. Fear of increased cancer risk, particularly breast cancer, is one reason for this. Due to low OC uptake and low screening participation, a paucity of data is available on the risk of OC use and breast cancer in Japanese women. The present study investigated OC use and breast cancer risk, as well as menstrual, reproductive and family factors. Materials and Methods: This was a clinic-based case-control study of women aged 20-69yrs who had undergone breast screening between January 2007 and December 2013 in central Tokyo. In all, 28.8% of the participants had experience with OC use. Cases were 155 women with a pathologically confirmed diagnosis of breast cancer. Controls were the remaining 12,333 women. Results: Increased age was a significant risk factor for breast cancer (p<0.001). A lower risk was found in premenopausal women presently taking OC compared to never users (OR 0.45; 95% CI 0.22-0.90) after adjusting for age, parity and breast feeding, and a family history of breast cancer. Conclusions: Increased age rather than OC use had a greater effect on breast cancer risk. This risk may be decreased in premenopausal women with OC use, but further long-term prospective studies are necessary.
Seo, Hyunwoong,Ichida, Daiki,Hashimoto, Shinji,Itagaki, Naho,Koga, Kazunori,Shiratani, Masaharu,Nam, Sang-Hun,Boo, Jin-Hyo American Scientific Publishers 2016 Journal of Nanoscience and Nanotechnology Vol.16 No.5
<P>The multiple exciton generation characteristics of quantum dots have been expected to enhance the performance of photochemical solar cells. In previous work, we first introduced Si quantum dot for sensitized solar cells. The Si quantum dots were fabricated by multi-hollow discharge plasma chemical vapor deposition, and were characterized optically and morphologically. The Si quantum dot-sensitized solar cells had poor performance due to significant electron loss by charge recombination. Although the large Si particle size resulted in the exposure of a large TiO2 surface area, there was a limit to ho much the particle size could be decreased due to the reduced absorbance of small particles. Therefore, this work focused on decreasing the internal impedance to improve charge transfer. TiO2 was electronically modified by doping with vanadium, which can improve electron transfer in the TiO2 network, and which is stable in the redox electrolyte. Photogenerated electrons can more easily arrive at the conductive electrode due to the decreased internal impedance. The dark photovoltaic properties confirmed the reduction of charge recombination, and the photon-to-current conversion efficiency reflected the improved electron transfer. Impedance analysis confirmed a decrease in internal impedance and an increased electron lifetime. Consequently, these improvements by vanadium doping enhanced the overall performance of Si quantum dot-sensitized solar cells.</P>
Analysis on the Photovoltaic Property of Si Quantum Dot-Sensitized Solar Cells
Hyunwoong Seo,Daiki Ichida,Giichiro Uchida,Kunihiro Kamataki,Naho Itagaki,Kazunori Koga,Masaharu Shiratani 한국정밀공학회 2014 International Journal of Precision Engineering and Vol. No.
This work first introduced Si quantum dots (QDs) for QD-sensitized solar cells (QDSCs). However, the particle size of Si QDs, which had visible light absorption, was relatively large. The paint-type Si QDSC was proposed in this work because Si QDs could not penetrate into nano-porous TiO2 network. Si QDs were synthesized by multi-hollow plasma discharge CVD and mixed with TiO2 paste. For better performance, thickness of Si-TiO2 layer was varied by coating times and Si-TiO2 films were optically and electrically analyzed. As a result, 6 times screen printed Si-TiO2 film had the best performance with the smallest internal impedance and the highest photon to current efficiency.