The role of hindrance stressors in the job demand–control–support model of occupational stress: A proposed theory revision

Previous research on the job demand–control–support (JDCS) model of occupational stress has generally been inconsistent at best regarding a key issue: the interaction of demands, control, and support in predicting employee health and well‐being. However, the model continues to be tested in a variety of studies and academic journals owing to its intuitive appeal. By incorporating conservation of resources theory with knowledge from the challenge–hindrance stressor framework, we proposed that hindrance stressors, not the challenge stressors commonly assessed when testing JDCS theory, will provide validation for the model. A two‐wave panel study of 228 employees in a variety of occupations provided support for three‐way interactions between hindrance demands, control, and support predicting job‐related anxiety and physical symptoms. Three‐way interactions using a challenge demand (forms of workload) were not significant, consistent with our propositions. In summary, this study supports the buffering effect of control and support on the relationship between job demands and strain only when job demands reflect hindrance stressors, thereby proposing to alter the JDCS model by specifying that it applies primarily to hindrance stressors in a job hindrance–control–support model. Copyright © 2015 John Wiley & Sons, Ltd.     

Degradation and mineralization of 2-chioro-, 3-chloro- and 4-chlorobiphenyl by a newly characterized natural bacterial strain isolated from an electrical transformer fluid-contaminated soil

A bacterium classified as Achromobacter xylosoxidans strain IR08 by phenotypic typing coupled with 16S rRNA gene analysis wasisolated from a soil contaminated with electrical transformer fluid for over sixty years using Aroclor 1221 as an enrichment substrate.The substrate utilization profiles revealed that IR08 could grow on all three monochlorobiphenyls (CBs), 2,4'- and 4,4'-dichlorobiphenylas well as 2-chlorobenzoate (2-CBA), 3-CBA, 4-CBA, and 2,3-dichlorobenzoate. Unusually, growth was poorly sustained on biphenyland benzoate. In growth experiments, IR08 degraded all CBs (0.27 mmol/L) in less than 96 h with concomitant stoichiometric release ofinorganic chloride and growth yields were 2-3 times higher than those observed on biphenyl. In contrast to most of the chlorobiphenyl-degrading strains described in the literature, which are reported to form CBA, no metabolite was identified in the culture broth byHPLC analysis. When co-incubated with respective CBs and biphenyl, strain IR08 preferentially utilized the chlorinated analoguesin less than 96 h while it took another 264 h before 90% of the initially supplied biphenyl could be degraded. The promotion of co-metabolic transformation of halogenated substrates by the inclusion of their non-halogenated derivatives may not therefore, result inuniversal benefits.     

光纤布拉格光栅传感器在钢架结构健康监测中的应用研究

光纤布拉格光栅(FBG)传感器凭借其体积小、灵敏度高、耐腐蚀、抗电磁干扰、分布或者准分布式测量、可实现远距离的监测与传输等优点,在土木工程健康监测中得到日益广泛的应用。本文在光纤布拉格光栅(FBG)传感器的传感原理、标定试验研究基础上,讨论了利用FBG传感系统监测钢架结构在冲击荷载作用下的应变和加速度的可行性;同时利用ANSYS有限元分析软件建立了适用于结构分析的有限元模型,对钢架结构进行了详细的仿真分析计算,最后对理论计算结果及实测结果进行了详细的对比分析,所取得的结果比较接近。研究表明,光纤布拉格光栅传感器可以很好的测量钢架结构的动态响应。     

一株异养脱氮菌的脱氮性能及其影响因素研究

研究异养硝化过程中分离得到一株具有异养脱氮性能的菌株,经16S rRNA鉴定后为Providencia rettgeri菌属,命名为Providencia rettgeri strain YL。在实验室条件下,初步探讨了不同碳氮源、温度、pH值、摇床转速和微量元素对Providencia rettgeri strain YL菌株脱氮作用的影响,研究结果显示,Providencia rettgeri strain YL菌株在葡萄糖和氯化铵为碳氮源的培养基中生长最好,温度为30℃、pH值为7、摇床转速为120 r/min时具有最佳的脱氮效果,微量元素Mg²⁺最有利于Providencia rettgeri strain YL菌株的生长和脱氮。     

利用广义应变花法计算地应变场

根据GPS测量的速度计算地应变是地球动力学研究中非常有意义的一项工作,但计算时涉及数值微分,如何减小其计算误差是一个突出的问题。本文提出将工程测量中的平面应变花分析方法推广到地球球面上的广义应变花方法;并通过对已知位移和应变场的特例下的数值实验,比较常用的最小二乘配置法和广义应变花方法计算应变的精度。结果显示广义应变花法应变的计算精度比最小二乘配置法高。     

降解1,2,4-三氯苯的硝基还原假单胞菌J5-1的分离鉴定和邻苯二酚1,2-双加氧酶基因的克隆

从受氯苯污染的土壤中分离到1株以1,2,4-三氯苯为唯一碳源生长的细菌,命名为J5-1.根据其生理生化特征和16S rDNA(GenBank Accession No.EF107515)序列相似性分析,将该菌株初步鉴定为硝基还原假单胞菌(Pseudomonas nitroreducens).当1,2,4-三氯苯初始浓度为400 mg/L时,J5-1对其最大降解率接近90%;当1,2,4-三氯苯浓度初始为20 mg/L时,降解效果最好.J5-1对1,2,4-TCB的降解服从一级反应动力学.从J5-1的基因组DNA中克隆到CC120的全长序列.     

Biodegradation of phenol and m-cresol by mutated Candida tropicalis

The phenol and m-cresol biodegradations were studied using the mutant strain CTM 2 obtained by the He-Ne laser irradiation on wild-type Candida tropicalis. The results showed that C. tropicalis exhibited the increased capacity of phenolic compounds degradation after laser irradiation. It could degrade 2600 mg/L phenol and 300 mg/L m-cresol by 5% inoculum concentration, respectively. In the dual-substrate biodegradation system, 0–500 mg/L phenol could accelerate m-cresol biodegradation, and 300 mg/L m-cresol could be completely utilized within 46 hr at the presence of 350 mg/L phenol. Besides, the maximum biodegradation of m-cresol could reach 350 mg/L with 80 mg/L phenol within 61 hr. Obviously, phenol, as a growth substrate, could promote CTM 2 to degrade m-cresol, and was always preferentially utilized as carbon source. Comparatively, low-concentration m-cresol could result in a great inhibition on phenol degradation. In addition, the kinetic behaviors of cell growth and substrate biodegradation were described by kinetic model proposed in our laboratory.     

润滑油高效降解菌的筛选及降解性能

实验以被石油污染的土壤为出发菌源,以润滑油为唯一碳源,经过筛选分离得到4株对润滑油具有降解能力的菌株。经过形态观察、生理生化实验初步鉴定发现,4株菌株分别为黄单胞菌属(Xanthomonas)、动胶菌属(Azotobac-ter)、假单胞菌属(Pseudomonas)和黄杆菌属(Flavobacterium),其中菌株G4为黄杆菌属,其润滑油降解效率最高。研究菌株G4降解性能的影响因素发现,实验中的各因素对润滑油降解率的影响大小依次为:温度>葡萄糖浓度>硫酸铵浓度>pH值。在温度20～40℃下,菌株G4对润滑油均具有一定的降解能力。在适宜的温度范围中,pH值5.0～9.0范围内,菌株G4的润滑油降解率随pH值的变化很小,且均在80%以上。菌株G4在以润滑油为唯一碳源时的最佳培养条件为:温度30℃,pH值为9.0,硫酸铵浓度为1.0 g/L。在此条件下培养36 h,100 mL的G4培养液对200μL润滑油的降解率可达84.6%。     

基因工程菌E.coli BL21-NiCoT吸附镍的性能研究

以表达Staphylococcus aureus ATCC6538镍钴转运酶NiCoT基因的基因工程菌E.coli BL21-NiCoT作为生物吸附剂处理含镍废水.结果表明:基因工程菌在pH为4～9时有比较好的吸附效果,30 min就达到了吸附平衡;基因工程菌对Ni2 的富集容量比原始宿主菌有很大的提高,最大平衡富集量从3.76 mg/g增加到11.33 mg/g,增幅达3倍多,溶液中Ni2 的最大去除率也从原来的35.62%增加到91.23%;Cu2 、Cr6 、Zn2 等的存在对吸附没有很大的影响.镍进入细胞内后与羟基和酰胺基团发生结合,蛋白类物质和含羟基类物质在细胞内富集镍的过程中起到重要作用;基因工程菌转接10、20、30、40、50次,重组质粒保持良好的结构稳定性,基因工程菌对镍的富集能力也具有较好的稳定性.     

一株纤维素降解细菌的分离及特性研究

从造纸厂污泥中分离得到了一株能以纤维素为唯一碳源生长良好的纤维素降解菌w 3 ,经鉴定 ,该菌株为假单胞菌属 (Pseu domonassp.) ,不产色。最适生长及产酶温度为 30℃ ,产酶最适pH值为 7.5 ,生长及产酶高峰出现在 2 0h ,比文献报道的时间提前较多 ,CMC酶活为 60 μg/min。另外 ,w 3能较好地适应微碱性的环境。对造纸废水处理非常有利。