新型炭复合材料吸附剂脱除汽油中硫化物的研究

制备了负载不同过渡金属离子（Ag^＋、Cu^2＋）的吸附剂Ag／Al2O3、Cu／Al2O3和Ag／SiO2，在固定床吸附脱硫装置上，考察了吸附剂对汽油模型化合物MGF-1（正庚烷中含噻吩硫760mg／L）的脱硫效果。结果表明，Ag／Al2O3具有较好的脱硫效果。将Al2O3在630℃下分别覆炭4，6，8h制得覆炭吸附剂，测定了覆炭吸附剂负载Ag^＋后对汽油模型化合物MGF-1和MGF-2的脱硫效果。结果表明，吸附剂覆炭后可明显提高吸附剂对硫化物的吸附选择性，当覆炭时间为6h时，吸附剂对硫化物的吸附选择性最好。     

快速一步法（ROSE法）提取DNA应用于RAPD—PCR扩增

对ＲＯＳＥ法的操作程序进行了进一步的简化，“一管一步”即可完成ＤＮＡ提取全过程，系统地与ＣＴＡＢ和ＳＤＳ法进行了比较，其提取过程明显比ＣＴＡＢ法、ＳＤＳ法简单，提取效率分别比ＣＴＡＢ、ＳＤＳ提高４倍和９倍，无污染物产生；与ＣＴＡＢ和ＳＤＳ法比分别节省费用约２００％和７００％。提取的ＤＮＡ能满足ＲＡＰＤ－ＰＣＲ研究的需要。因此，改良后的ＲＯＳＥ法可能是一种适合于ＤＮＡ提取自动化的方法，同时可能成为植     

The renal medullary thick ascending limb as a model for understanding lipid mediators in sepsis

OBJECTIVE: To evaluate the impact of HIV illness on psychiatric and psychosocial functioning over 3 years in a sample of male and female HIV-positive injecting drug users (IDU), with a comparison group of HIV-negative male and female IDU. DESIGN: As part of a multidisciplinary study, 121 men (69 HIV-positive, 52 HIV-negative) and 66 women (36 HIV-positive, 30 HIV-negative) were evaluated semiannually for seven visits. Attrition, unrelated to sex or serostatus, was 33%. RESULTS: At baseline, rates of major depression and dysthymia ranged from 15% (HIV-negative men) to 33% (HIV-positive men and HIV-negative women). Global impairment was in the range found in psychiatric patients (mean Global Assessment of Functioning scores, 46-51). Higher levels of social support and less social conflict were independently associated with decreased distress and improved global functioning among both men and women. For both HIV-positive groups, degree of improvement over time was related to degree to HIV progression: those who remained healthier in terms of CD4 count and illness stage showed more improvement. HIV-seronegative status was associated with less distress for men but not for women. Overall, women reported higher levels of psychiatric distress than men. CONCLUSIONS: High rates of psychopathology were found in this IDU cohort, independent of HIV status and sex. Although rates of psychopathology, injecting drug use and distress declined slightly during the study, they remained elevated; accordingly, psychiatric services are indicated for this population.     

Heterogeneity in intensive care units: fact or fiction?

Weight reduction, either by dietary or surgical means, is associated with prolongation of the heart rate corrected QT interval (QTc = QT/R-R0.5) and, on occasion, sudden death. Screening subjects with obesity before weight loss for prolonged QTc intervals is an accepted practice, although at present, there are no guidelines for whether subjects should be fasting before electrocardiogram (EKG) evaluation. The aim of this study was to test the hypothesis that EKG QTc interval duration is independent of meal ingestion. The hypothesis was tested in 11 healthy subjects who ingested a 500-kcal formula meal. A small decrease in absolute QT interval and a steady decline in R-R interval were observed for up to 60 minutes after formula ingestion. The QTc interval increased above baseline at 15 minutes (p < 0.007) after meal, a change that persisted for the 1-hour postmeal observation period. Spectral analysis of EKG R-R intervals (low-/high-frequency amplitude ratio) indicated a change in cardiac autonomic flow after meal ingestion. The QTc interval did not lengthen and R-R low-/high-frequency amplitude ratio remained unchanged in eight subjects evaluated in a similar manner but in whom isovolumic amounts of water replaced the meal. These observations suggest that (1) cardiac repolarization changes with fasting and feeding, (2) the QTc interval is influenced by meal intake, and (3) the autonomic nervous system may play a role in meal-related QTc changes. These findings have implications for the evaluation of patients with obesity before starting and during weight loss treatment.     

Three-dimensional stress analysis of polypropylene leaflets for prosthetic heart valves

The effect of changing the modulus and thickness of the material in the leaflets of an artificial heart valve has been investigated. This has been achieved with a finite element model of the valve having approximately 2300 thin shell elements. The valve motion and the resulting stresses are modelled dynamically during closure, and subsequent pressurisation. The stresses decrease as the leaflets are made thicker and the modulus is increased. Local and global thickening has been investigated. The highest stresses appear at the tops of the stent posts in the regions of the commissures. When the modulus is too low, or the leaflets are too thin, the valve prolapsed.     

Activation of NMDA and non-NMDA receptors in the caudal ventrolateral medulla dilates the airways

Calpain is a ubiquitous calcium-dependent cysteine protease, whose cytoskeletal protein substrates suggest that it may be important in neuronal differentiation. Lead (Pb2+) is known to substitute for Ca2+ in a variety of intracellular processes, and interferes with the development of hippocampal neurons in vitro. We found that free Pb2+ at 1 nM does not activate calpain in the absence of Ca2+. Pb2+ inhibited the activity of calpain; the degree of calpain inhibition was dependent on an interaction between concentrations of both Ca2+ and Pb2+. In the presence of 1 microM free Ca2+, 10 pM free Pb2+ reduced calpain activity, but in the presence of 100 microM free Ca2+, 1 nM free Pb2+ failed to inhibit calpain. This provides evidence that Pb2+ competes for the Ca2+ binding sites on calpain. In the presence of 40 microM free Ca2+, 1 nM free Pb2+ significantly reduces Vmax without altering Km, suggesting that Pb2+ acts as a noncompetitive inhibitor of calpain. Inhibition of calpain is one mechanism by which Pb2+ may interfere with neuronal development.     

龚嘴大坝坝基渗出物成因分析研究

对龚嘴电站大坝坝基渗出物的特征、类型和成分以及渗出量的动态变化进行了研究，探讨了渗出物质的主要可能来源和成因机制。研究认为，渗出物的主要成分为铁、锰、钙的氧化物，由于其实际的元素渗出量不大，不会对大坝安全造成有意义的不利影响。     

Nursing in Brazil

The goal of International Perspectives is to share the views of nurse leaders, from countries other than the United States, on global healthcare issues. The focus is on identifying healthcare management problems and their implications, research priorities, policy development, and ethical-moral dilemmas faced by nurse administrators. You are encouraged to send the names and addresses of international nurse leaders who might be interested in participating, as well as your ideas, for format and content of the department.     

Theory for microwave thermal emission from a layer of cloud or rain

Microwave thermal emission from a layer of cloud or rain consisting of spherical particles has been investigated. Scattering effects are studied in great detail with both numerical and analytical approaches. In the absence of ground emission, it is found that scattering induces brightening for optically thin layers and vice versa for optically thick layers. As a function of observation angle brightening occurs near nadir while darkening occurs at large angles in the case of small optical thickness. For large optical thickness, darkening occurs at all angles because of backscattering effects. When the layer of cloud or rain is above an air layer and an ocean surface at a higher temperature, it is found that the darkening effect at large optical thickness is much more pronounced. The darkening effect is also larger for vertical polarizations because the ocean emits more vertically polarized components. The effect of thermal emission and molecular absorption by atmospheric gases is also taken into account. Results obtained from analytical formulas under single scatteirng assumptions are compared and illustrated.