秀丽线虫转基因品系在环境暴露评价与毒理学研究中的应用

目前,模式动物秀丽线虫已被广泛应用于环境暴露评价和环境毒理学研究中.在系统介绍了各种秀丽线虫转基因品系在环境暴露与毒性评价以及环境毒理研究中的应用进展基础上,分析了秀丽线虫转基因品系在环境暴露与毒性评价研究中的灵敏性与直观性的特点.最后,讨论了秀丽线虫转基因品系在环境暴露与毒性评价以及环境毒理研究中尚存在的问题和可能的...     

ABAQUS混凝土损伤塑性模型的动力性能分析

地震作用在混凝土结构上会在其材料中产生较高的应变率,混凝土材料具有一定的率敏感性,准确模拟混凝土结构在地震作用下的反应需采用混凝土动态本构模型.为评估ABAQUS有限元软件中的混凝土损伤塑性模型模拟混凝土动力性能的能力,采用该模型对混凝土材料和构件在不同加载速度下的动态反应进行了有限元数值分析.结果表明,随着加载速度的...     

基于灵敏度分析的斜拉桥拉索更换顺序研究

通过对部分换索桥梁换索顺序的调研,按照拉索不同的布置形式,总结了目前拉索更换所采用的主要顺序,并利用有限元分析方法对某双塔双索面斜拉桥进行了模拟换索,分析得到了偏于安全的换索顺序。通过拆单根索的弯曲应变能的变化,分析了斜拉桥换索的整体顺序。通过分析不同换索工况下的索力增量变化规律,包括单塔拆1根、双塔同侧索面对称拆4根、双塔不同侧索面反对称拆4根等3种工况,对拉索更换顺序进行了研究,并对其中的同侧索面和不同侧索面拆除4根拉索的工况进行了主梁线形的分析,建立了有限元模型。分析认为,斜拉桥拉索的更换宜从短索向长索反对称进行。     

产脲酶菌株Sporosarcina ureilytica ML-2诱导方解石沉淀矿化Pb（II）、Cd（II）和Cr（VI）研究

微生物诱导方解石沉淀（MICP）作为一种新兴的重金属生物治理技术已逐渐成为研究热点.基于脲酶作为MICP反应的核心驱动力,本研究筛选获得1株拥有致密胞外聚合物,且产脲酶活性和菌体Zeta电位强于产脲酶代表性菌株Sporosarcina pasteurii的MICP功能菌株Sporosarcina ureilytica ML-2.在生物矿化50 mg·L^-1 Pb（II）、Cd（II）和Cr（VI）离子实验中,Cd（II）较Pb（II）和Cr（VI）对菌株ML-2产脲酶代谢活性存在显著性抑制（p<0.01）,实验组仅24 h和48 h即可去除全部的Pb（II）和Cd（II）,而96 h时仅能去除约12.14%的Cr（VI）.生物沉淀SEM形貌显示不同类型重金属可通过影响生物矿化过程无机晶体成核生长方向,从而改变沉淀形貌;EDS表征证实菌株ML-2可通过诱导方解石沉淀有效固定Pb（II）和Cd（II）,而对Cr（VI）无法实现有效固定;FTIR表征则证实羧基、羟基、胺基和烷基等功能基团共同参与重金属的矿化固定.结合天然方解石吸附初始浓度为200 mg·L^-1的Pb（II）、Cd（II）和Cr（VI）离子实验及对应沉淀的XRD图谱,再一次证实Pb（II）以方解石钙位点替代形式被矿化成白铅矿（PbCO₃）,Cd（II）的目标矿化产物菱镉矿（CdCO₃）可能因质量分数过低等原因虽未被检出,但依然实现了高效固定,并再次确认MICP无法有效固定Cr（VI）.最后,MICP矿化固定Pb（II）和Cd（II）污染的过程模型被构建,将为后续的扩大应用提供理论指导.     

Exploring the linkage between the home domain and absence from work: Health,motivation, or both?

The aim of this study was twofold. First, we examined depleting and enriching effects of employees' home domain (home demands and quality time spent at home) on unscheduled absence from work. Second, we tested the assumption of the medical and withdrawal models that absence duration and frequency are uniquely predicted by respectively health condition and job motivation. We used longitudinal, different‐source data from 1014 employees. The results showed that home quality time was negatively related to absence frequency and duration in the following year through a physical pathway (less physical stress symptoms and health complaints) and through a psychological pathway (less psychological stress symptoms, increased job motivation). Employees with heavy home demands reported more physical and psychological stress symptoms, more health complaints, and lower job motivation. Accordingly, they had longer and more frequent sick leaves in the consecutive year. We conclude that the home domain adds to our understanding of absence from work. In addition, the model including cross pathways between health complaints and job motivation on the one hand, and absence frequency and duration on the other, best fitted the data. Thus, a clear distinction between volitional absence (frequency) and absence due to illness (duration) seems hard to justify. Copyright © 2012 John Wiley & Sons, Ltd.     

Physical Strain and Work Ergonomics in Farmers with Disabilities

In agriculture, occupational injuries are common, and several of them lead to permanent physical disability. The objective of this case study was to assess the strain and the ergonomic needs of four farmers (aged 34–49 years) with physical disabilities. A maximal bicycle ergometer test or an arm-crank test was done to assess their maximal heart rate (HR _max) and maximal oxygen consumption (V0_2max). The strain at work was analyzed by measuring heart rate (HR), muscle activity (EMG), and the rating of perceived exertion (RPE). The farmers were interviewed as to possible and impossible work tasks and the ergonomic redesign measures taken to improve the work environment. The work tasks performed were mainly light or moderate work for the cardiorespiratory system according to mean HR (88-102 beats/min), the percentage of HR range (17–31% HRR), and the relative V0₂ (22–46% V0_2max). The mean activity of the trapezius muscles was 0.4-9% of the maximal voluntary contraction (%MVC). All the participants had work tasks they were unable to perform. They had made ergonomie redesign changes mainly to the tractor. This case study showed that some agricultural work tasks were possible for farmers with physical disabilities and that the physical strain associated with these tasks was mainly light or moderate.     

A ventilation cooling shirt worn during office work in a hot climate: cool or not?

The aim of the study was to identify whether a ventilation cooling shirt was effective in reducing heat strain in a hot climate. Eight female volunteers were exposed to heat (38?°C, 45% relative humidity) for 2?h with simulated office work. In the first hour they were in normal summer clothes (total thermal insulation 0.8?clo); in the second hour a ventilation cooling shirt was worn on top. After the shirt was introduced for 1?h, the skin temperatures at the scapula and the chest were significantly reduced (p?<?0.05). The mean skin and core temperatures were not reduced. The subjects felt cooler and more comfortable by wearing the shirt, but the cooling effect was most conspicuous only during the initial 10?min. The cooling efficiency of the ventilation shirt was not very effective under the low physical activity in this hot climate.     

Stressful work characteristics,health indicators and work behavior: the case of machine operators

This article shows the results of research on psychosocial risks for a group of machine and plant operators (n?=?1014) from the construction, chemical, energy, mining, metal and food industries in Poland. The Psychosocial Risk Scale designed in Nofer Institute of Occupational Medicine (NIOM) by Moscicka-Teske and Potocka was used to indicate the occurrence of general and specific occupational stressors and the level of their stressfulness. The results revealed that the studied machine and plant operators experience job context stress – related to working environment features concerning work organization – more frequently than job content stressors – related to the type of tasks they perform. Moreover, a correlation analysis between work features and the health and occupational functioning of the respondents revealed significant but weak relationships between the variables (from ?0.08 to ?0.23). Comparative analysis revealed the differences between the studied sectors. Such a comparison makes it possible to set goals for each sector and to attempt to improve the distinctive areas.     

The Relationship Between Shift Work Schedules and Spillover in a Sample of Nurses

The aim of the present study was to estimate spillover effects between the work and the family sphere in a sample of nurses (N = 2058). Hierarchical regression analyses investigated whether shift work schedules were associated with negative or positive spillover, both from family to work and vice versa, controlling for demographic factors, job demands and decision latitude. With daytime work as a reference group, all types of shift work (day and evening shift, night shift only and rotating 3 shift) were associated with higher negative work-to-family spillover. Night work was associated with significantly less negative family-to-work spillover. None of the different shift work schedules were related to any type of positive spillover. The results indicate that working outside of daytime hours is less compatible with workers’ family lives, compared to working ordinary day shifts. On the other hand, working night shifts only was associated with reduced negative family-to-work spillover.     

考虑岩石应变软化的厚煤层综放开采覆岩破坏特征研究

为了分析裴沟矿31采区的煤炭开采对上部魔洞王水库的影响,以及评价水体下开采的安全性,首先分析了岩土体材料在三轴压缩试验中表现出来的应变软化现象,认为岩石峰后的软化能够说明覆岩破坏后的力学特性;然后介绍了FLAC3D中应变软化模型;最后分别建立Mohr—Coulomb理想弹性模型和应变软化模型的数值模型,针对工作面推进过程中覆岩移动破坏的特征以及顶板导水裂隙带发育规律,分析了两者计算结果的差别,计算结果表明:应变软化模型对覆岩移动破坏特征的计算更加准确,能够说明工作面推进过程中覆岩移动规律,通过其计算得到的导水裂隙带高度的预计对水体下采煤的安全性评价有一定的参考价值。