Cross‐national job stress: a quantitative and qualitative study

Using both quantitative and qualitative methods, this study contrasted employees' job stress perceptions and their relationships to strains in China and the United States. Significant job stressor–strain correlations were found in both countries. However, hierarchical regression analyses revealed significant interactions of country by job stressors in predicting job strains, indicating the unique patterns of stressor–strain relationships in China and the United States. In the qualitative analyses, American employees reported significantly more incidents of lack of job control, direct interpersonal conflict, lack of team coordination, anger, frustration, feeling overwhelmed, and stomach problems than the Chinese. Chinese employees reported significantly more incidents of job evaluations, work mistakes, indirect conflict, employment conditions, lack of training, anxiety, helplessness, sleep problems, and feeling hot than the Americans. The qualitative approach contributed above and beyond the quantitative results in that it revealed culture‐specific job stressors of job evaluations, work mistakes, and indirect conflict that had been overlooked in western‐based stress research. Copyright © 2007 John Wiley & Sons, Ltd.     

三段式硝化型生物接触氧化反应器的启动及特性

采用实际生活污水,研究了三段式串联的硝化型生物接触氧化反应器的挂膜启动及各段的硝化特性.试验结果表明:利用中间沉淀池出水作为生物接触氧化反应器的进水进行自然挂膜,在无需投加接种污泥的情况下,20d挂膜成熟,NH4+-N的去除率达到98%以上.反应器中随着沿程推流,三段的生物量和生物膜厚度逐渐降低,最大的生物量和生物膜厚度分别为1271.25mg/L和119.45μm.分析各段的硝化特性,发现三段在低温15℃条件下仍具有较高的比硝化速率,并且在同一温度下(15,23,32℃),第2、3段的比硝化速率均大于第1段.针对上述现象,根据比耗氧速率SOUR粗略估计了AOB和NOB在各段中的相对比例.3段AOB的百分比分别为(25.64+4.89)%, (34.59+5.02)%, (42.50+1.57)%,而NOB的百分比为(23.52+3.35)%, (39.65+4.26)%, (40.69+2.19)%. 此外,系统运行125d的FISH结果表明,3段的微生物菌群分布确实存在差异.与第1段相比,后2段的AOB和NOB更容易成为优势菌.     

Occurrence of bisphenol A in surface and drinking waters and its physicochemical removal technologies

Bisphenol A (BPA), an endocrine disrupting compound, has caused wide public concerns due to its wide occurrence in environment and harmful effects. BPA has been detected in many surface waters and drinking water with the maximum concentrations up to tens of μg·L^-1. The physicochemical technology options in eliminating BPA can be divided into four categories: oxidation, advanced oxidation, adsorption and membrane filtration. Each removal option has its own limitation and merits in removing BPA. Oxidation and advanced oxidation generally can remove BPA efficiently while they also have some drawbacks, such as high cost, the generation of a variety of transformation products that are even more toxic than the parent compound and difficult to be mineralized. Only few advanced oxidation methods have been reported to be able to mineralize BPA completely. Therefore, it is important not only to identify the major initial transformation products but also to assess their estrogenic activity relative to the parent compounds when oxidation methods are employed to remove BPA. Without formation of harmful by-products, physical separation methods such as activated carbon adsorption and membrane processes are able to remove BPA in water effluents and thus have potential as BPA removal technologies. However, the necessary regeneration of activated carbon and the low BPA removal efficiency when the membrane became saturated may limit the application of activated carbon adsorption and membrane processes for BPA removal. Hybrid processes, e.g. combining adsorption and biologic process or combining membrane and oxidation process, which can achieve simultaneous physical separation and degradation of BPA, will be highly preferred in future.     

热成形和热处理对3.5Ni钢力学性能的影响

本文研究了不同厚度3.5Ni低温钢板以不同热成形加热温度和冷却条件成形后的力学性能变化。通过对经历热成形同样加热和冷却条件的母材试板重新进行不同规范的正火和回火,对材料被损坏的性能进行了恢复和提高,为低温钢设备的制造提供了可靠的工艺依据。     

川藏公路滑坡加固预应力锚索受力分析研究

以川藏公路102滑坡群滑坡处理为依托,仔细研究了滑坡体的工程地质特征。对由大型松散堆积物形成的2#滑坡锚索加固工程稳定性进行了研究,由于在2#滑坡中,滑动面和预应力锚索之间的夹角很大,作用在锚索上面的力还包括轴向拉力和侧向的弯矩和剪力。通过对力的分析和计算证明,使用梁单元来进行计算更加符合实际使用要求,因此,预应力锚索的应用不仅能够合理地改善结构的受力条件,并且能够充分地利用材料本身的强度特性,节约了工程的使用费用,具有很好的推广应用价值。     

Trace metal pollution in a Le'an River tributary affected by non-ferrous metal mining activities in Jiangxi Province,China

Sediment and water samples from the Jishui River were tested to determine the concentrations of As, Cd, Cu, Mn, Pb and Zn. The concentrations of Cu, Mn and Zn in the surface water close to the Fujiawu copper mine greatly exceeded the criteria maximum concentrations (CMC) of the Environmental Protection Agency. The concentration of Zn at a site near the small smelters also exceeded the CMC. Cd concentrations in surface water samples from 69% of the sampling sites were significantly higher than the CMC. Heavy Cd pollution of surface water resulted from the Shuanghua Smelter, the lead smelter, the lead–zinc mine and the small smelters downstream. The total metal concentrations in the majority of the sediment samples substantially exceeded the probable effect levels (PEL). Levels of As, Cd, Cu and Zn in surface sediment of the site close to the Shuanghua Smelter were 20 times higher than the PELs. The levels of Pb in sediment of the downstream sites near the small smelters and the lead–zinc mine were also elevated. Based on the results of the BCR sequential extract procedures and the risk assessment code, the levels of Cd, Cu, Mn and Zn in the sediment posed high risk.     

生物效应比(BER)技术预测我国水生生物基准探讨

基于中国与美国间生物敏感性的差异,对生物效应比(BER)技术预测我国水生生物基准值进行了研究.首先,对中美共有的且急性生物毒性数据符合3门8科的污染物进行筛选,然后,依据两国物种的敏感性与代表性建立基于不同生物组合的BER技术,最后,对不同生物组合BER技术预测水生生物急性基准值与实测基准值进行比较与分析,筛选出预测效果较好的BER技术.结果表明:共筛选出9个中美共有且毒性数据丰富的污染物(As(III)、Cr(VI)、Hg、Cu、Zn、Pb、对硫磷、毒死蜱和三丁基锡),依据本土生物毒性数据推导出该9种污染物的我国水生生物急性基准值分别为201.72、2.64、0.74、1.32、55.83、92.25、0.12、0.36和0.38μg/L.此外,在对7种生物组合方式BER技术的预测效果进行分析比较的基础上,初步提出基于同属或科的生物组合方式的BER技术可较好地对9种污染物的本土水生生物急性基准值进行预测.研究结果可为在本土生物毒性数据缺乏时充分利用现有毒性数据或进行少量毒性试验的基础上对我国水生生物急性基准值的预测提供帮助.     

Relations between indoor and outdoor PM2.5 and constituent concentrations

Factors impacting indoor-outdoor relations are introduced. Sulfate seems a fine tracer for other non-volatile species. Particulate nitrate and ammonium desorb during outdoor-to-indoor transport. OC load increases during the transport due to sorption of indoor SVOCs. Outdoor PM_2.5 influences both the concentration and composition of indoor PM_2.5. People spend over 80% of their time indoors. Therefore, to assess possible health effects of PM_2.5 it is important to accurately characterize indoor PM_2.5 concentrations and composition. Controlling indoor PM_2.5 concentration is presently more feasible and economic than decreasing outdoor PM_2.5 concentration. This study reviews modeling and measurements that address relationships between indoor and outdoor PM_2.5 and the corresponding constituent concentrations. The key factors in the models are indoor-outdoor air exchange rate, particle penetration, and deposition. We compiled studies that report I/O ratios of PM_2.5 and typical constituents (sulfate (SO₄^2-), nitrate (NO₃^-), ammonium (NH₄⁺), elemental carbon (EC), and organic carbon (OC), iron (Fe), copper (Cu), and manganese (Mn)). From these studies we conclude that: 1) sulfate might be a reasonable tracer of non-volatile species (EC, Fe, Cu, and Mn) and PM_2.5 itself; 2) particulate nitrate and ammonium generally desorb to gaseous HNO₃ and NH₃ when they enter indoors, unless, as seldom happens, they have strong indoor sources; 3) indoor-originating semi-volatile organic compounds sorb on indoor PM_2.5, thereby increasing the PM_2.5 OC load. We suggest further studies on indoor-outdoor relationships of PM_2.5 and constituents so as to help develop standards for healthy buildings.     

带有耗能连梁的钢筋混凝土剪力墙结构地震损伤评估

为了评估目前广泛研究的新型带有耗能连梁的剪力墙结构损伤程度,提出了一种适用于该结构的损伤模型,并通过低周反复试验结果对损伤模型进行验证。提出了该结构的地震性能等级及相应的损伤指数范围,并通过地震作用的增量动力分析得到该结构的易损性曲线,对该结构进行地震损伤评估。结果表明:提出的损伤模型能较好描述带有耗能连梁的钢筋混凝土剪力墙结构的损伤发展,地震性能等级及相应的损伤指数范围能较好反映该种结构的破坏等级,得到的易损性曲线能较为有效评估该种结构的损伤程度,为基于性能的新型带有耗能连梁的剪力墙结构的抗震设计及损伤评估提供了参考。     

我国潜在顾客对城市美食的偏好与影响因素研究--基于网络关注度视角

通过收集网络关注度等数据,利用赫芬达尔—赫希曼指数、皮尔逊相关系数、多元回归分析等方法分析了我国31个省份潜在顾客对10个典型城市美食的偏好与影响因素。结果发现:①同一性别、年龄和地区的潜在顾客对不同城市美食偏好程度均不同,男性潜在顾客对美食的偏好程度略高于女性潜在顾客,美食的潜在顾客以中青年为主。②不同性别、年龄和地区的潜在顾客对同一城市美食的偏好也存在明显差异。③人们对美食的偏好程度与可支配收入之间存在正相关关系,与空间距离之间存在负相关关系。④地域文化、宗教信仰、气候等因素也会对潜在顾客的美食偏好产生影响。