Air Filtration and Radon Decay Product Mitigation

Air cleaning as a means of mitigating the risks arising from exposure to indoor radon progeny has been evaluated in a single-family house in the north eastem US. using an automated, semi-continuous activity-weighted size distribution measurement system. The measurements included radon concentration, condensation nuclei count, and activity-weighted size distribution of radon decay products. Measurements were made in the house with and without an operating air filtration system and with various particle sources common to normal indoor activities operating. Aerosols were generated by running water in a shower, candle burning, cigarette smoking, vacuuming, opening doors, and cooking. Using a room model, the changes in attachment rates, average attachment diameters, and deposition rates of the unattached fraction with and without the air cleaning system were calculated. In the presence of active aerosol sources, the air filtration unit typically reduced the concentration of particles within the hour following the end of particle generation. After candle burning, cigarette smoking, and vacuuming in the bedroom, the reductions of PAEC by air filtration are about 60% with the air filtration system operating in the bedroom. During cooking in the kitchen, the reductions of PAEC in the bedroom with the air filtration system were about 40%. However, for all cases the dose reductions were smaller than the particle and PAEC reductions. For those particles that were generated within the bedroom, there was a 20% to 50% reduction in dose. In the case of cooking where the door was open and particles infiltrated from the rest of the house, the dose reduction was only 5% on average and appears to be insignificant. Thus, the dose reductions were h e r than the reductions in activity concentration, but there were no cases where the estimated dose actually increased.     

混流式水轮机转轮叶片径向焊接收缩与开口值关系初探

为生产出优质混流式水轮机焊接转轮,本文用求解转轮开口值的图解法探讨了转轮装焊时叶片与下环之间焊缝径向焊接收缩对转轮开口值的影响,并给出了两者之间的关系。     

Modeling the intact form of the {alpha}1-proteinase inhibitor

The structure of the intact form of the serpin ₁-proteinaseinhibitor has been modeled based on the assumption that thecentral strand s4A of the six-stranded ß-sheet A ofthe cleaved inhibitor is not incorporated into the sheet ofintact ₁-proteinase inhibitor. This strand was removed fromits position in the center of the sheet by suitable rotationsabout the backbone dihedrals of Lys343 using molecular graphics.The resulting structure was then annealed using molecular dynamics(MD) while applying progressive distance restraints to the reactivepeptide bond (Met358-Ser359) for 50 ps. During this time, thedisrupted ß-sheet reformed to create a five-strandedß-sheet with strands 3 and 5 in a parallel arrangement.This change and accompanying structural rearrangements are largelyconfirmed by the X-ray structure of plakalbumin, whose structurereflects the overall structure of intact serpins. The successfulmodeling experiment demonstrates the utility of MD for makinggross structural predictions based on related structures. Thebinding loop of the intact form is modeled to allow dockingwith serine proteinases, in particular thrombin, which mosthighly constrains the possible conformations of the bindingloop.     

Oxidatively modified LDL and atherosclerosis: An evolving plausible scenario

Much evidence has accumulated that implicates the oxidative modification of low‐density lipoprotein (LDL) in the early stages of atherogenesis. The antioxidant nutrients alpha‐tocopherol, ascorbic acid, and beta‐carotene have been shown to inhibit in vitro LDL oxidation. In addition, they have been shown to increase the resistance of LDL to oxidation when given to animals and humans. Because plasma levels of these nutrients can be increased by dietary supplementation with minimal side effects, they may show promise in the prevention of coronary artery disease.     

HOP INDUSTRY COMMITTEE: ANALYSIS OF HOPS OF THE 1980 CROP

Analytical values for α-acid content of thirteen varieties of hops from the 1980 crop are presented in relation to the district of production. For all varieties the tolerance aim of ±0·5% was achieved this year and variability of the crop was generally the same as the average for the last five years. As before, the results are acceptable for commercial purposes. The sampling rates have been considered and a minor reduction in the rate for Wye Target is justified.     

Atlantic salmon (Salmo salar) muscle structure integrity and lysosomal cathepsins B and L influenced by dietary n-6 and n-3 fatty acids

This study had two main objectives: first, to evaluate the impact of different types and levels of dietary n-6 and n-3 fatty acids (FAs) on Atlantic salmon muscle structure integrity; second, to highlight a possible role of lysosomes and lysosomal degrading enzymes, cathepsins, in fish muscle structure integrity, in relation to dietary fatty acids. Four groups of Atlantic salmon (90 g starting weight) in fresh water tanks were fed one of four diets containing 23% crude lipids, with 100% of the added oils as either fish oil (FO), rapeseed oil (RO), eicosapentaenoic acid (EPA) enriched-oil or docosahexaenoic acid (DHA) enriched-oil. The RO diet was characterised by low levels of EPA + DHA (10% of total FAs), whereas the EPA and DHA diets were characterised by very high levels of EPA + DHA (>50% of total FAs). Fatty acid composition of the muscle crude lysosomal fraction (CLF) generally reflected the diets. Salmon fed the RO diet presented a muscle CLF FA composition close to the one of the FO group, showing moderate PUFA levels, and comparable cathepsin B and cathepsin L activities, relative gene expression of cathepsin B and cathepsin L in the muscle and rate of myofibre–myofibre detachments post-mortem. Salmon fed the EPA and DHA-enriched-oil diets presented a fairly similar muscle CLF FA composition, but different from the FO and RO groups. In the EPA and DHA groups, the percentage of PUFAs in the muscle CLF, the rate of myofibre–myofibre detachments and the relative gene expression of cathepsin B were higher than in the FO and RO groups. Cathepsin B and cathepsin L total activities in the muscle were however lower in the EPA and DHA groups 0 h post-mortem. Dietary lipids influenced the level of lysosomal degrading enzyme activity cathepsin B and cathepsin L as well as the relative gene expression of cathepsin B. Feeding Atlantic salmon with rapeseed oil and extreme levels of EPA + DHA highlighted the impact of fatty acid composition of the diet on salmon muscle integrity and the complexity of the process involving muscle lysosomes and cathepsins in relation to these dietary fatty acids.     

苦荞黄酮对α-淀粉酶的抑制作用研究

为了比较研究各种不同提取方法下的苦荞黄酮对α-淀粉酶的抑制作用,分别对苦荞总黄酮溶液、苦荞水溶性黄酮溶液、苦荞醇溶性黄酮溶液用α-淀粉酶进行体外活性抑制作用试验,并绘制抑制曲线,所得的结果与阿卡波糖进行比较。结果表明:阿卡波糖、苦荞总黄酮、苦荞水溶性黄酮、苦荞醇溶性黄酮对α-淀粉酶均有抑制作用,其半抑制浓度(IC50)值分别为0.095、0.086、0.10、0.202 mg/mL。本研究为三种提取产物在防治糖尿病及其并发症等方面的应用提供参考,具有较大的理论意义和应用价值。     

Nd:YAG激光治疗白内障超声乳化术后囊袋皱缩的临床观察

目的观察Nd:YAG激光前囊切开术治疗白内障超声乳化术后囊袋皱缩的临床效果。方法回顾分析2004年3月至2005年3月白内障超声乳化术后囊袋皱缩35例35眼的临床资料,患眼均接受Nd∶YAG激光前囊四象限放射状切开术,术后随访3～9个月(平均5.7±2.5月)。结果术后35眼最佳矫正视力均不低于术前,囊袋皱缩未再继续进展,无严重并发症发生。结论Nd∶YAG激光前囊切开治疗白内障超声乳化术后囊袋皱缩安全有效,早期治疗效果更佳。     

Alpha-Helical Structure of Fish Actomyosin: Changes during Setting

Participation of the α-helix in setting was investigated using circular dichroism. The α-helicity of the actomyosin from eight species of fish decreased during incubation at 30°C or at 40°C. The extent and pattern of decrease differed among species. When rate of decrease was plotted vs rate of increase in strength of gel preincubated at 30°C or at 40°C, the two factors correlated closely. We propose that the unfolding of α-helix initiated setting.     

求最佳配比的模拟压缩算法

研究了无放大效应的生产过程中各原料的配比问题，建立了一种模拟压缩模型，给出了求最佳配比的算法。