Comparison of different liquid anaerobic digestion effluents as inocula and nitrogen sources for solid-state batch anaerobic digestion of corn stover

Effluents from three liquid anaerobic digesters, fed with municipal sewage sludge, food waste, or dairy waste, were evaluated as inocula and nitrogen sources for solid-state batch anaerobic digestion of corn stover in mesophilic reactors. Three feedstock-to-effluent (F/E) ratios (i.e., 2, 4, and 6) were tested for each effluent. At an F/E ratio of 2, the reactor inoculated by dairy waste effluent achieved the highest methane yield of 238.5 L/kgVS_feed, while at an F/E ratio of 4, the reactor inoculated by food waste effluent achieved the highest methane yield of 199.6 L/kgVS_feed. The microbial population and chemical composition of the three effluents were substantially different. Food waste effluent had the largest population of acetoclastic methanogens, while dairy waste effluent had the largest populations of cellulolytic and xylanolytic bacteria. Dairy waste also had the highest C/N ratio of 8.5 and the highest alkalinity of 19.3 g CaCO₃/kg. The performance of solid-state batch anaerobic digestion reactors was closely related to the microbial status in the liquid anaerobic digestion effluents.     

基于CFD分析的呼吸防护面具罩体设计

分析呼吸防护面具研究领域在呼吸阻力方面的研究情况,提出基于计算流体力学分析的呼吸防护面具罩体设计方案,在设计过程中添加以计算流体力学分析为手段的有限元模拟仿真模块。通过ANSYS产品ICEM CFD与CFX对设计模型进行网格划分与流体分析,根据仿真结果对初步设计的模型进行结构优化再设计。     

Mental health outcomes of job stress among Chinese teachers: role of stress resource factors and burnout

This study examined the mental health outcomes of job stress among Chinese teachers in Hong Kong. A total of 269 Chinese teachers participated in Study 1 which provided cross‐sectional data regarding the associations among stress resource factors, burnout, and negative mental health. Study 2 was a six‐month longitudinal study which aimed to establish the direction of the associations among the hypothesized variables across two time points with a separate sample of 61 Chinese secondary school teachers. Results of the structural equation modelling analyses on the cross‐sectional data at T1 showed that stress resource factors of self‐efficacy and proactive attitude were negatively related to burnout, which in turn had a direct effect on negative mental health. Stress resource factors were also directly linked to mental health status of teachers. Results of similar analyses on the longitudinal data at T2 further indicated that burnout at T1 had a direct impact on burnout at T2, which in turn had a direct effect on negative mental health at T2. Findings and limitations of the study were discussed. Copyright © 2001 John Wiley & Sons, Ltd.     

一起预制板脆性断裂事件的原因及预防

对发生在该钢铁厂的一起预制板脆性断裂事件进行了介绍和分析,探讨了在高温条件下发生断裂的原因。     

工业有毒物质防治的技术措施

简要介绍了几种毒物防治的技术措施。     

汉江上游郧县曲远河河口段全新世古洪水水文状态研究

对汉江上游河谷郧县曲远河河口剖面进行了沉积学、粒度、磁化率和烧失量的研究。结果表明：夹在古土壤中的灰白色沉积层是典型的古洪水滞流沉积物，记录了一次特大洪水事件，用地层对比法和OSL方法确定其发生时间为4 950~5 450 a B.P.。用古洪水SWD尖灭点法确定古洪水行洪水位高程为169 m，采用比降法恢复其洪峰流量为60 577 m3/s。根据2011年汉江上游洪水洪痕，用相同的方法对洪峰流量进行了反演，误差为-411％，说明用比降法恢复的古洪水洪峰流量是可靠的