Reversible photochromic photocatalyst Bi2O3/TiO2/Al2O3 with enhanced visible photoactivity: application toward UDMH degradation in wastewater.

1,1-Dimethylhydrazine (UDMH) and its by-products were considered carcinogenic toxins and represent a serious health hazard to the population once present in water under natural conditions without treatment. The conventional degradation method suffers from incomplete removal of intermediate products (especially N-nitrosodimethylamine (NDMA)), the powdery catalysis being difficult to recover and results in high energy consumption. In this study, a series of Bi2O3/TiO2/Al2O3 (BTA) photocatalysts have been successfully synthesized by a simple dry mixing method with powder material followed by their immobilization. It was evaluated by the photocatalytic degradation of UDMH present in wastewater, which can be recovered by rapid filtration and utilizes only solar energy. The catalyst exhibited markedly enhanced photocatalytic activity for the degradation of UDMH wastewater compared with conventional TiO2/Al2O3 (TA) catalysts under UV, visible and solar irradiation. Besides, the intermediate NDMA was gradually completely degraded. The photocatalysts were extensively characterized using scanning electron microscopy, energy dispersive spectrometry, specific surface area (BET), X-ray diffraction, X-ray photoelectron spectroscopy, UV-visible diffuse reflectance spectroscopy and photo-electrochemical I-t curves evaluation. The results revealed that all the BTA composites exhibited high stability and stronger absorbance in visible light. In addition, the BTA exhibited a reversible photochromic property that can effectively expand the range of light absorption and enhance the photocatalytic activity. The reversible photochromic properties of BTA explained in the proposed mechanism model are expected to be useful for detecting and sensing UDMH or other organic contaminants.

[Relationship between serum prostate-specific antigen levels and body mass index in Beijing men over 50 years of age].

OBJECTIVE: To investigate the relationship between body mass index (BMI) and serum prostate specific antigen (PSA). METHODS: A cross-sectional study was performed at community of Beijing in men over 50 years old. Height, weight and PSA (both serum TPSA and FPSA) were assessed in 1573 men. According to the redefined World Health Organization (WHO) criterion for Asia Pacific Region, BMI was categorized as light weight (BMI < 18.5 kg/m2), normal (18.5 kg/m2 < or = BMI < 23.0 kg/m2), overweight (23.0 kg/m2 < or = BMI < 25.0 kg/m2), obese (25.0 kg/m2 < or = BMI < 30.0 kg/m2) and severe obese (BMI > or = 30 kg/m2). SPSS 13.0 was used in BMI and PSA statistical analysis. RESULTS: Mean age was (64 +/- 10) years, mean BMI (24 +/- 3) kg/m2, PSA median 1.0 (0.6 - 1.9) microg/L and mean prostate volume(30 +/- 18) ml. BMI classification: low weight 54 cases (3.43%), normal weight 441 (28.04%), overweight 423 patients (26.89%), obesity 597 patients (37.95%) and severe obesity 58 (3.69%). We adjusted the low weight group and severe obesity group into normal group and obesity group respectively for small sample capacity. After adjustment, there was no significance difference (P = 0.75) between PSA level of normal group and that of obesity group. However, the PSA level of normal group and overweight group versus obesity group respectively, there were significant differences (P = 0.002, 0.010). After adjusting for age and prostate volume, the correlation between BMI and PSA was negative. BMI showed no significant correlation with PSA in different age groups. CONCLUSION: BMI and PSA were negatively correlated. BMI should be considered as a factor (esp. for obese or severe obese) in man undergoing prostate cancer screening.