Electrochemical synthesis of Pd particles on poly(vinylferrocenium)

Electrochemical synthesis of Pd particles on poly(vinylferrocenium) (PVF⁺) support was described. K₂PdCl₄ was used as the metal particle precursor. Pd particles were incorporated into the polymer matrix electrochemically either by cyclic voltammetric scans (between +1.0 V and −0.8 V vs. SCE) or by reduction at constant potential (at −0.8 V vs. SCE) from aqueous solution of K₂PdCl₄. Scanning electron microscopy (SEM) studies showed that the Pd particles were well dispersed in the polymer matrix. Experimental parameters such as polymer film thickness, number of cycles during cyclic voltammetric scans in K₂PdCl₄ and electrolysis time in K₂PdCl₄ were studied. The Pd/PVF⁺ system showed catalytic activity towards hydrazine oxidation and appreciable results were obtained when compared with the related studies.     

氟化处理对植入材料Mg-Ca二元合金腐蚀行为的影响(英文)

在室温下,将Mg-0.5Ca合金在不同浓度的氢氧化钠和HF溶液浸渍不同的时间,研究HF处理对合金腐蚀行为的影响。采用原子力显微镜、X射线衍射、场发射扫描电子显微镜表征样品的微观组织变化。通过动电位极化和Kokubo溶液浸泡试验测试样品的耐腐蚀性。结果表明,与35%HF处理的样品相比,经40%HF溶液处理的Mg-0.5Ca合金具有更均匀、更致密、更薄的涂层(12.6μm)。电化学测试表明,在Kokubo溶液中,经氟化物处理的Mg-0.5Ca合金样品的耐腐蚀性比未处理样品的高35倍;前者的体外降解速率远远低于后者的。在40%HF溶液处理过的样品表面只出现了一些腐蚀点,而未经处理的样品完全被腐蚀产物覆盖且出现了分层现象。40%HF处理的Mg-0.5Ca合金,具有低的降解速率和良好的生物相容性,是一种有潜力的植入材料。     

Health and social impacts of improved stoves on rural women: a pilot intervention in Sindh, Pakistan

To assess the acceptability, social and health impacts of improved stoves among women. A cross-sectional study was conducted from April to May 2002 among households using improved stoves in the two villages of District Thatta and Hyderabad, Sindh, Pakistan. A questionnaire was administered to 45 women using improved stoves named Smoke Free Stoves (SFS). The same questionnaire was administered to a sample of 114 women, using Traditional Stoves (TS). Carbon monoxide (CO) levels were measured in a sample of both groups. Multivariate analysis was carried out to adjust for confounders. In addition, focus group discussions (FGDs) were conducted to evaluate the perception of women regarding acceptability and impact of SFS on women. A majority of women reported that SFS produce less smoke and have a beneficial impact on their health. In the multivariate analysis, symptoms of dry cough (AOR=0.61; 95% CI 0.26-1.41), sneezing (AOR=0.54; 95% CI 0.22-1.30) and tears while cooking (TWC) (AOR=0.51; 95% CI 0.21-1.21) are less likely to occur in women using SFS compared to TS. However, the results were not statistically significant possibly due to the small sample. The mean (+/-s.e.) CO levels were 15.4+/-3.4 ppm in SFS and 28.5+/-5.7 ppm in TS kitchens with a mean difference of -13.1 (95% CI -29.5 and 3.2). The results indicate a trend favorable for SFS and suggest that a larger scale project should be undertaken to reach to a definitive conclusion, ideally using a longitudinal design. PRACTICAL IMPLICATIONS: In order to enhance IAQ in kitchens in developing regions of the world stoves for burning of biomass should be constructed in a way that the emission of fuel gases are low. In this way the risk of negative health effects will be reduced.