SummaryThe inhibitory activity of six groups of flavonoids against yeast and rat small intestinal ␣ -glucosidases and porcine pancreatic ␣ -amylase was compared, and chemical structures of flavonoids responsible for the inhibitory activity were evaluated. Yeast ␣ -glucosidase was potently inhibited by the anthocyanidin, isoflavone and flavonol groups with the IC 50 values less than 15 M . The following structures enhanced the inhibitory activity: the unsaturated C ring, 3-OH, 4-CO, the linkage of the B ring at the 3 position, and the hydroxyl substitution on the B ring. Rat small intestinal ␣ -glucosidase was weakly inhibited by many flavonoids, and slightly by the anthocyanidin and isoflavone groups. 3-OH and the hydroxyl substitution on the B ring increased the inhibitory activity. In porcine pancreatic ␣ -amylase, luteolin, myricetin and quercetin were potent inhibitors with the IC 50 values less than 500 M . The 2,3-double bond, 5-OH, the linkage of the B ring at the 3 position, and the hydroxyl substitution on the B ring enhanced the inhibitory activity, while 3-OH reduced it.
A laser patterning method was investigated as a fabrication method for integrated-type amorphous-silicon (a-Si) solar cell submodules. A three-dimensional thermal analysis of a multilayer structure was performed to determine the selective scribing conditions for each layer of an a-Si solar cell. The optimum laser power densities calculated from a three-dimensional thermal analysis were confirmed by the experiments. It was found that not only transparent conductive oxide and a-Si films, but also the metal electrodes of the integrated-type a-Si solar cell submodule were selectively scribed.
The total output power of an a-Si solar cell submodule patterned by optimum laser-power densities was 9% higher than that achieved by a conventional patterning method.
For further improvement of conversion efficiency in a-Si solar cells, it is necessary to develop materials with high photosensitivity in the long-wavelength region. A new solid phase crystallization (SPC) method was developed to grow a Si crystal at temperatures as low as 600°C. Using this method, high-quality thin-film polycrystalline silicon (poly-Si) with a Hall mobility of 70 cm2/V·s was obtained. Quantum efficiency in the range of 800 nm ∼ 1000 nm was achieved up to 80% in an experimental solar cell using the n-type poly-Si with a grain size of about 1.5 µm. Therefore, it was found that our SPC method was suitable as a new technique to prepare high-quality solar cell materials.
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