Enhancement of blue-green photoluminescence in B2O3 fritted ZrO2:Ce3+ phosphor

Blue-green emission of ZrO₂:Ce³⁺ phosphor, prepared by solid-state reaction, is demonstrated. The phosphor presents a strong and broad photoluminescence band centered at 496 nm with excitation at 291 nm. The optimized Ce content is 2.5 mol% for the strongest emission of ZrO₂:Ce³⁺ phosphors prepared without B₂O₃. The PL intensity is enhanced by at least 3 dB by adding 5.0 mol% B₂O₃ within the ZrO₂:Ce³⁺ containing 5.0 mol% Ce during synthesis. Increase of the B₂O₃ flux effectively induces the Ce ions to substitute the Zr ions in ZrO₂ lattice and causes the ZrO₂ lattice distortion. The formation of Ce_0.75Zr_0.25O₂ compound within the ZrO₂:Ce³⁺ occurred when the Ce content is greater than or equal to 2.5 mol% for the phosphors prepared without B₂O₃ and leads to a degradation of the phosphor PL intensity due to the host effect. The addition of B₂O₃ during the preparation of phosphors containing Ce ions lower than or equal to 5.0 mol% essentially restrains the Ce_0.75Zr_0.25O₂ formation and then enhances the blue-green PL.     

Effects of Oolong Tea Supplementation on Lipid Peroxidation of Athletes at Rest and Post-exhaustive Exercise

ABSTRACT: Oolong tea contains polyphenolic catechins that can act as antioxidants and improve blood lipid status. The purpose of this study was to investigate the effect of a daily intake of Oolong tea for 30 d on the cholesterol profiles, lipid peroxidation level, and superoxide dismutase activity in athletes before and after exhaustive exercise. Twenty-two male rugby players served as the experiment subjects. They were divided into 2 groups: the tea-supplement group and control group. The results showed that there was a significant increase in total plasma cholesterol for both groups after training. There were no significant differences in the high-density lipoprotein (HDL) cholesterol level and low-density lipoprotein (LDL) cholesterol level after tea supplementation. However, ingestion of Oolong tea resulted in significantly lower resting and post-exhaustive exercise level of plasma malondialdehyde, and significantly lower resting level of superoxide dismutase activity. The results suggest that supplementation with Oolong tea for rugby players can decrease oxidative stress, and this can be explained by the decrease of lipid peroxidation level in cooperation with Oolong tea supplementation against the free radicals.