Piceatannol is a stilbenoid, a metabolite of resveratrol found in red wine. Piceatannol and sera from rats orally given piceatannol were found to dose-dependently suppress both the proliferation and invasion of AH109A hepatoma cells in culture. Its antiproliferative effect was based on cell cycle arrest at lower concentration (25~50 μM) and on apoptosis induction at higher concentration (100 μM). Piceatannol suppressed reactive oxygen species-potentiated invasive capacity by scavenging the intracellular reactive oxygen species. These results suggest that piceatannol, unlike resveratrol, has a potential to suppress the hepatoma proliferation by inducing cell cycle arrest and apoptosis induction. They also suggest that the antioxidative property of piceatannol, like resveratrol, may be involved in its anti-invasive action. Subsequently, piceatannol was found to suppress the growth of solid tumor and metastasis in hepatoma-bearing rats. Thus, piceatannol may be a useful anticancer natural product.
Influence of Ti addition (substitution for Cu) on Tc is studied for high Tc Bi1.6Pb0.4Sr2Ca2(Cu1−zTiz)3Ox. An abnormal Tc change is found between z=0.01 and 0.1. Based on results of the electrical resistivity and x-ray diffraction, the abnormal Tc change is discussed.
The effect of compressive stress on ${\mathit{T}}_{\mathit{c}}$ is studied for the low-${\mathit{T}}_{\mathit{c}}$ ${\mathrm{Bi}}_{1.6}$${\mathrm{Pb}}_{0.4}$${\mathrm{Sr}}_{2}$${\mathrm{Ca}}_{2}$${\mathrm{Cu}}_{3}$${\mathrm{O}}_{\mathit{x}}$ phase. Although stress decreases the ${\mathit{T}}_{\mathit{c}}$ of the high-${\mathit{T}}_{\mathit{c}}$ sample, the small compressive stress increases the ${\mathit{T}}_{\mathit{c}}$ of the low-${\mathit{T}}_{\mathit{c}}$ phase. The maximum ${\mathit{T}}_{\mathit{c}}^{\mathrm{off}}$ is about 113.6 K at 0.01 mA/${\mathrm{mm}}^{2}$ (current density) and 3.92 N/${\mathrm{mm}}^{2}$ of the low-${\mathit{T}}_{\mathit{c}}$ phase where ${\mathit{T}}_{\mathit{c}}^{\mathrm{off}}$ is 96.2 K before loading. The maximum ${\mathit{T}}_{\mathit{c}}^{\mathrm{off}}$ is larger than the unloaded value (109.3 K) of the high-${\mathit{T}}_{\mathit{c}}$ ${\mathrm{Bi}}_{1.6}$${\mathrm{Pb}}_{0.4}$${\mathrm{Sr}}_{2}$${\mathrm{Ca}}_{2}$${\mathrm{Cu}}_{3}$${\mathrm{O}}_{\mathit{x}}$ sample. Based on the results of x-ray-diffraction, electrical-resistivity, and Seebeck-effect measurements, the ${\mathit{T}}_{\mathit{c}}$ is dominated by carrier concentration and crystal perfection of the lattice ordering.
The oxygen concentration in Y-Ba-Cu-O is one of the dominant factors to control the superconducting properties. Since oxygen concentration is controlled by the cooling rate, the cooling rate affects the superconducting properties. The lattice constant of the c-axis is related to oxygen concentration. Thus, we undertook to obtain the change of superconducting properties (Tc and Jc) and the lattice constant of the c-axis with the cooling rate in Y-Ba-Cu-O. The cooling curves were dominated Newton analysis.Based on the relaxation theory, we showed the existence of an approximately linear relationship between the lattice constant of the c-axis and the cooling rate, between Tc and the cooling rate and between Jc at 15K and the cooling rate. we conclude that the relaxation theory can be explained by oxygen concentration change in oxygen-deficient perovskite of Y-Ba-Cu-O.The abnormal Jc change is found from 45 to 65K for slow cooled specimen. The probable explanation is discussed by two phases. The slow cooled specimen has the ortho-I (matrix) and the ortho-II, the ortho-II can be the pinning site and then causes the abnormal Jc change.
